• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
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    • 专利摘要:
    A variable cam timing phaser arrangement (201) is disclosed, comprising:. a rotor (9) having at least one vane;. a stator (7) co-axially surrounding the rotor (9), having at least one recess for receiving the at least one vane of the rotor, wherein the at least one vane divides the at least one recess into a first chamber (11) and a second chamber (13); and a control assembly for regulating hydraulic fluid flow from the first chamber (11) to the second chamber (13) or vice-versa. The control assembly comprises a central on /off piloted valve (15) for allowing or preventing fluid flow along a first unidirectional flow path between the first (11) and second (13) chambers, and a central solenoid valve (37) for allowing or preventing fluid flow along a second unidirectional flow path between the first (11) and second (13) chambers in the opposite direction to the first flow path.The present disclosure further relates to an integrated valve unit for use in the variable cam timing phaser arrangement, and a method of controlling the timing of a camshaft in an internal combustion engine. The disclosure also relates to an internal combustion engine and a vehicle comprising the disclosed variable cam timing phaser arrangement.(Fig. 1)
    公开号:SE1650712A1
    申请号:SE1650712
    申请日:2016-05-24
    公开日:2017-11-25
    发明作者:Eriksson Mikael；Olovsson Daniel
    申请人:Scania Cv Ab；
    IPC主号:
    专利说明:

    1 Variable cam timing phaser having two central control valves TECHNICAL FIELD The present invention concerns a variable cam timing phaser arrangement for an internalcombustion engine as well as a method for controlling the timing of a camshaft in an internalcombustion engine using such a variable cam timing phaser. The invention also concerns aninternal combustion engine and a vehicle comprising such a variable cam timing phaser affafigemefit.
    BACKGROUND ART The valves in internal combustion engines are used to regulate the flow of intake and exhaustgases into the engine cylinders. The opening and closing of the intake and exhaust valves in aninternal combustion engine is normally driven by one or more camshafts. Since the valvescontrol the flow of air into the engine cylinders and exhaust out of the engine cylinders, it iscrucial that they open and close at the appropriate time during each stroke of the cylinderpiston. For this reason, each camshaft is driven by the crankshaft, often via a timing belt ortiming chain. However, the optimal valve timing varies depends on a number of factors, suchas engine load. ln a traditional camshaft arrangement the valve timing is fixedly determined bythe relation of the camshaft and crankshaft and therefore the timing is not optimised over theentire engine operating range, leading to impaired performance, lower fuel economy and/orgreater emissions. Therefore, methods of varying the valve timing depending on engine conditions have been developed.
    One such method is hydraulic variable cam phasing (hVCP). hVCP is one of the most effectivestrategies for improving overall engine performance by allowing continuous and broadsettings for engine-valve overlap and timing. lt has therefore become a commonly used technique in modern compression-ignition and spark-ignition engines.
    Both oil-pressure actuated and cam torque actuated hydraulic variable cam phasers are known in the art. 2 The oil-pressure actuated hVCP design comprises a rotor and a stator mounted to thecamshaft and cam sprocket respectively. Hydraulic oil is fed to the rotor via an oil controlvalve. When phasing is initiated, the oil control valve is positioned to direct oil flow either toan advance chamber formed between the rotor and stator, or a retard chamber formedbetween the rotor and stator. The resulting difference in oil pressure between the advancechamber and the retard chamber makes the rotor rotate relative to the stator. This eitheradvances or retards the timing ofthe camshaft, depending on the chosen position ofthe oil control valve.
    The oil control valve is a three-positional spool valve that can be positioned either centrally,i.e. co-axially with the camshaft, or remotely, i.e. as a non-rotating component of the hVCParrangement. This oil control valve is regulated by a variable force solenoid (VFS), which isstationary in relation to the rotating cam phaser (when the oil control valve is centrallymounted). The variable force solenoid and the spool valve have three operational positions:one to provide oil to the advance chamber, one to provide oil to the retard chamber, and one to refill oil to both chambers (i.e. a holding position).
    The established oil pressure actuated hVCP technology is effective in varying valve timing, buthas relatively slow phasing velocities and high oil consumption. Therefore, the latest iterationsof hVCP technology utilise a technique known as cam torque actuation (CTA). As the camshaftrotates the torque on the camshaft varies periodically between positive torque and negativetorque in a sinusoidal manner. The exact period, magnitude and shape ofthe cam torquevariation depends on a number of factors including the number of valves regulated by thecamshaft and the engine rotation frequency. Positive torque resists cam rotation, whilenegative cam torque aids cam rotation. Cam torque actuated phasers utilize these periodictorque variations to rotate the rotor in the chosen direction, thereby advancing or retardingthe camshaft timing. ln principle they operate as ”hydraulic ratchets", allowing fluid to flow ina single direction from one chamber to the other chamber due to the torque acting on the oilin the chambers and causing periodic pressure fluctuations. The reverse direction of fluid flowis blocked by check valve. Therefore, the rotor will be rotationally shifted relative to the statorevery period the torque acts in the relevant direction, but will remain stationary when thetorque periodically acts in the opposite direction. ln this manner, rotor can be rotated relative to the stator, and the timing of the camshaft can be advanced or retarded. 3 Cam torque actuation systems therefore require check valves to be placed inside the rotor inorder to achieve the ”hydraulic ratchet" effect. The directing of oil flow to the advancechamber, retard chamber, or both/neither (in a holding position) is typically achieved using athree-positional spool valve. This spool valve can be positioned either centrally, i.e. co-axiallywith the camshaft, or remotely, i.e. as a non-rotating component ofthe cam phasingarrangement. The three-positional spool valve is typically moved to each of the three operative positions using a variable force solenoid.
    Patent application US 2008/0135004 describes a phaser including a housing, a rotor, a phasercontrol valve (spool) and a regulated pressure control system (RCPS). The phaser may a camtorque actuated phaser or an oil pressure activated phaser. The RPCS has a controller whichprovides a set point, a desired angle and a signal bases on engine parameters to a directcontrol pressure regulator valve. The direct control pressure regulator valve regulates a supplypressure to a control pressure. The control pressure moves the phaser control spool to one of three positions, advance, retard and null, in proportion to the pressure supplied.
    There remains a need for improved cam timing phaser arrangements. ln particular, thereremains a need for cam timing phaser arrangements that are suitable for use commercialvehicles, which are often subject to heavier engine loads and longer service lives as compared to passenger cars.SUMMARY OF THE INVENTION The inventors of the present invention have identified a range of shortcomings in the prior art,especially in relation to the use of existing cam phaser arrangements in commercial vehicles. lthas been found that the three-positional spool valves of the oil control valve (OCV) in presentsystems must be precisely regulated and therefore are sensitive to impurities that mayjamthe spool in a single position. Due to the need for three-position regulation, the solenoids orpressure regulators used in conjunction with the oil control valve must be able to be preciselyregulated to provide varying force, in order to attain three positions. This adds considerablemechanical complexity to the system, making it more expensive, more sensitive to impurities and less robust. lt also makes the routines for controlling the cam phaser more complex. 4 lt has been observed that that when the oil control valve is solenoid-actuated and centrallymounted the contact between the solenoid-pin and the oil control valve is non-stationarysince the oil control valve rotates and the solenoid-pin is stationary. This sliding-contact wearsthe contact surfaces and the position accuracy of the oil control valve is compromised over thelong-term which affects the cam phaser performance. The accuracy ofthe variable force solenoid itself must also remain high to ensure precise control over the OCV.
    Further, oil leakage of existing cam phaser arrangements is also a problem. Cross-port leakageinside the oil control valve cause oil to escape the hydraulic circuit and increase camshaftoscillations due to decreased system stiffness. This leakage also affects the oil consumption ofthe cam phaser arrangement. lt has been observed that the three-positional spool valves usedin regulating oil flow offer many different leakage paths for oil to escape the cam phaserchambers. I/lost noticeable is the sliding contact surface closest to the variable force solenoidwhere the valve is solenoid-actuated, as well as the port connected to vent. This leakageincreases with increased pressure inside the cam phaser chambers since all the pressurespikes in the system must be absorbed by the oil control valve. These pressure spikes are inturn dependent on camshaft torque and may exceed 50 bars for commercial vehicles.Camshaft torques are higher in heavy-duty vehicles, causing higher pressure spikes and even more leakage. lt has been observed that existing cam phasing systems utilising remotely-mounted oil controlvalves suffer from even greater system leakage because the pressure spikes from the camphaser must be transmitted through the camshaft journal bearing before reaching the oil control valve, therefore increasing bearing leakage.
    Further, it has been found that the rotor of existing cam torque actuated phasing systems isvery compact and complex. Specially-designed check valves must be mounted in the rotor inorder to fit in conjunction with the oil control valve. Such check valves are less durable thanconventional check valves and add additional expense. Moreover, the rotor requires acomplex internal hydraulic pipe system. Due to these requirements, the manufacturing of cam torque actuated cam phasers requires special tools and assembling. 5Thus, it is an object ofthe present invention to provide a variable cam timing phaserarrangement utilizing cam torque actuation that is mechanically simpler, more robust and less prone to oil leakage than known cam torque actuated cam phasers.
    This object is achieved by the variable cam timing phaser arrangement according to the appended claims.The variable cam timing phaser arrangement comprises:a rotor having at least one vane, the rotor arranged to be connected to a camshaft; a stator co-axially surrounding the rotor, having at least one recess for receiving the at leastone vane of the rotor and allowing rotational movement of the rotor with respect to the stator, the stator having an outer circumference arranged for accepting drive force; wherein at least one vane divides the at least one recess into an first chamber and a secondchamber, the first chamber and the second chamber being arranged to receive hydraulic fluidunder pressure, wherein the introduction of hydraulic fluid into the first chamber causes therotor to move in a first rotational direction relative to the stator and the introduction ofhydraulic fluid into the second chamber causes the rotor to move in a second rotationaldirection relative to the stator, the second rotational direction being opposite the first rotational direction; and a control assembly for regulating hydraulic fluid flow from the first chamber to the second chamber or vice-versa.The control assembly comprises: a piloted valve located centrally within the rotor, the piloted valve comprising a pilot port, afirst flow port in fluid communication with the first chamber, and a second flow port in fluidcommunication with the second chamber, wherein the piloted valve is switchable between anopen state and a closed state by regulation of the pressure of a pilot fluid at the pilot port,wherein in the open state the piloted valve allows fluid communication between the firstchamber and second chamber, and in the closed state the piloted valve prevents fluid communication between the first chamber and the second chamber; 6a first check valve arranged in a fluid path between the piloted valve and the first chamber,the first check valve arranged to allow flow from the piloted valve to the first chamber, but to prevent flow from the first chamber to the piloted valve; a solenoid-controlled actuator located remotely from the rotating components of the variablecam timing phaser arrangement and in fluid communication with the pilot port of the pilotedvalve, the solenoid-controlled actuator having at least two states, a primary state and asecondary state, wherein the solenoid-controlled actuator is arranged to switch the pilotedvalve from the open state to the closed state when the solenoid-controlled actuator switchesfrom the primary state to the secondary state, and wherein the solenoid-controlled actuator isarranged to switch the piloted valve from the closed state to the open state when thesolenoid-controlled actuator switches from the secondary state to the primary state, by regulating the pressure of the pilot fluid at the pilot port; a central solenoid valve having a valve body arranged co-axially within the rotor and/orcamshaft, the central solenoid valve comprising a first flow port in fluid communication withthe first chamber and a second flow port in fluid communication with the second chamber,wherein the central solenoid valve is switchable between a closed state preventing fluidcommunication between the first chamber and second chamber and an open state allowing fluid communication between the first chamber and the second chamber; and a second check valve arranged in a fluid path between the central solenoid valve and thesecond chamber, the second check valve arranged to allow flow from the central solenoidvalve to the second chamber, and to prevent flow from the second chamber to the central solenoid valve.
    A variable cam timing phaser arrangement constructed in this manner has a number ofadvantages. lt is constructionally simple, requiring only simple on/off valves to control the camphaser. The cam phaser is more robust due to less complex and/or less sensitive hydrauliccomponents compared to other cam torque actuated cam phasers. The use of onlyconstructionally robust on/off valves and the avoidance of transferral of pressure spikesthrough the camshaft bearings means that oil escape paths are fewer and oil consumptionlower. The risk of valves jamming is lowered since any valves used need take only two positions meaning that a greater actuating force and/or stronger return mechanisms can be 7used. More robust solenoids can be used since intermediate position accuracy is not needed.Similarly, no fine multi-pressure regulation is needed to actuate the on/off piloted valve.
    Further advantages may be apparent to the ski|ed person.
    The variable cam timing phaser arrangement may utilize hydraulic oil as the hydraulic fluidand/or pilot fluid. Cam phasers utilizing hydraulic oil are well established. By utilizing hydraulicoil as the pilot fluid, the construction of the cam phaser arrangement is simplified and alternative routes for refilling the cam phaser with oil are made available.
    The piloted valve may be a 2/2 way on/off valve, arranged to be normally in the open state,and actuated by increased fluid pressure at the pilot port to switch to the closed state. Suchvalves are readily-available, well-established and sufficiently robust to provide reliable service in commercial and heavy vehicle applications.
    The solenoid-controlled actuator may be a 3/2 way on/off solenoid valve having an inlet portin fluid communication with a source of increased fluid pressure, an outlet port in fluidcommunication with the pilot port ofthe piloted valve, and a vent port, wherein the primarystate ofthe solenoid valve is a de-energised state preventing fluid communication from thesource of increased fluid pressure to the pilot port of the piloted valve and allowing fluidcommunication from the pilot port of the piloted valve to the vent port, and wherein thesecondary state of the solenoid valve is an energised state allowing fluid communication fromthe source of increased fluid pressure to the pilot port ofthe piloted valve and actuating thepiloted valve. Such solenoid valves are readily-available, well-established and sufficientlyrobust to provide reliable service in commercial and heavy vehicle applications. The solenoid valve may be of the poppet-type, which virtually eliminates the risk for valve jam.
    The solenoid-controlled actuator may comprise a solenoid-driven piston arranged in acylinder, the cylinder being arranged in fluid communication with the pilot port ofthe pilotedvalve, wherein the primary state ofthe solenoid-driven piston is a retracted de-energisedstate and the secondary state ofthe solenoid-driven piston is an extended energised state, theextended state increasing the pressure of the fluid at the pilot port of the piloted valve. Thisincreased fluid pressure may be used to actuate the piloted valve. Thus the actuation pressure of the piloted valve need not be dependent on the system oil pressure ofthe vehicle. Utilising 8a cylinder actuator, the actuation pressure can be designed to be higher than the oil system pressure, or lower, if desired. This allows for greater system robustness.
    The central solenoid valve may be a 2/2 way on/off solenoid valve arranged to be normally inthe closed state, and actuated by energising the solenoid to switch to the open state. Suchvalves are again readily-available, well-established and sufficiently robust to provide reliable service in commercial and heavy vehicle applications.
    From a failsafe perspective it may be an advantage having a piloted valve that is normallyopen in combination with a central solenoid valve that is normally closed. Thus, in the event ofsolenoid failure, the rotor is moved to base position by cam torque actuation, meaning that the use of a torsion spring biasing mechanism for the rotor may be avoided.
    A source of increased fluid pressure, such as a main oil gallery, may be arranged in fluidcommunication with the first chamber and the second chamber via a first refill channel and asecond refill channel, the first refill channel and second refill channel each having a checkvalve arranged to prevent fluid flow from the first chamber or second chamber to the sourceof increased fluid pressure. This ensures that the cam phaser is sufficiently supplied with oilfor optimal performance and that the cam phaser system is sufficiently rigid to avoid camshaft vibration.
    The piloted valve, the central solenoid valve, the first check valve and the second check valvemay be integrated into a single integrated valve unit arranged co-axially with the rotor. Theuse of an integrated valve unit reduces the number of separate components needed to control the cam phaser, thereby simplifying manufacture and reducing manufacturing cost.The integrated valve unit comprises: A cylindrical housing comprising a cylindrical wall, a first end wall arranged to seal a first endof the cylindrical housing and a second end wall arranged to seal a second end ofthecylindrical housing, wherein the cylindrical wall ofthe housing comprises a first hole throughthe cylindrical wall in proximity to the first end wall of the housing, a second hole through thecylindrical wall in proximity to a middle portion of the cylindrical housing, and a third hole through the cylindrical wall in proximity to the second end wall ofthe housing; a first valve seat arranged in the housing between the first hole and the second hole; 9 a second valve seat arranged in the housing between the second hole and the third hole; a first valve member arranged to be normally seated on the first valve seat, the first valvemember arranged to prevent flow from the first hole to the second hole, but to allow flow from the second hole to the first hole; a second valve member arranged to be normally seated on the second valve seat, the secondvalve member arranged to prevent flow from the second hole to the third hole, and to allow flow from the third hole to the second hole; a first valve sleeve arranged outside and co-axially with the housing in proximity to the firstend of the housing and arranged to be moveable between an open position and a closedposition when subjected to altered external fluid pressure from a pilot fluid, wherein the openposition allows fluid flow through the first hole, and the closed position prevents fluid flow through the first hole; and a second valve sleeve arranged outside and co-axially with the housing in proximity to thesecond end ofthe housing and arranged to be moveable between a closed position and anopen position by the action of a solenoid, wherein the closed position prevents fluid flow through the third hole, and the open position allows fluid flow through the third hole.
    Using such a construction, the integrated valve unit can be formed from well-proven valvecomponents such as sliding valve sleeves and valve members such as ball or disc valvemembers. Since much functionality is incorporated into a single unit, space is saved. The checkvalve functionality is located centrally in the integrated valve unit meaning that conventionalrobust valve members and seats can be used, in contrast to small, specially manufactured radially placed check valves in known commercial cam-toque actuated phasers.
    The first hole and the third hole may each arranged to be in fluid communication with a firstchamber ofthe variable cam timing phaser arrangement, and the second hole may bearranged to be in fluid communication with a second chamber ofthe variable cam timingphaser arrangement. Connected in this manner, the integrated valve unit may be used as adirect replacement for the piloted valve, central solenoid valve, first check valve and second check valve as described above.
    The first valve sleeve may normally be in the open position and may be moveable to theclosed position when subjected to increased fluid pressure. The second valve sleeve may benormally in the closed position and may be moveable to the open position by energising thesolenoid. Thus, if the solenoids fail to actuate, the integrated valve unit returns the rotor tobase position using cam torque actuation, meaning that a torsion spring may not be required to bias the cam phaser to base position.
    According to another aspect of the invention, a first method for controlling the timing of acamshaft in an internal combustion engine comprising a variable cam timing phaser arrangement as described above is provided. The method comprises the steps: i. Providing the solenoid-controlled actuator in a secondary state, therebyproviding the piloted valve in a closed state, and providing the central solenoid valve in a closed state; ii. Switching the solenoid-controlled actuator to the primary state, therebyswitching the piloted valve to an open state, whereby fluid will flow from the second chamberto the first chamber due to periodic pressure fluctuations in the first chamber and secondchamber caused by torque acting on the camshaft, and whereby fluid is prevented fromflowing from the first chamber to the second chamber, resulting in the rotor rotating in a firstrotational direction relative to the stator and the cam timing being adjusted in a first temporal direction; iii. I/|aintaining the solenoid controlled actuator in the primary state until a desired degree of cam timing phasing is achieved; iv. Switching the solenoid-controlled actuator to a secondary state, therebyswitching the piloted valve to a closed state, whereby fluid communication between the firstchamber and the second chamber is prevented and the desired degree of cam timing phasing is maintained.
    According to yet another aspect of the invention, a second method for controlling the timing of a camshaft in an internal combustion engine comprising a variable cam timing phaser 11i. Providing the solenoid-controlled actuator in a secondary state, therebyproviding the piloted valve in a closed state, and providing the central solenoid valve in a closed state; ii. Switching the central solenoid valve to the open state, whereby fluid will flowfrom the first chamber to the second chamber due to periodic pressure fluctuations in the firstchamber and second chamber caused by torque acting on the camshaft, and whereby fluid isprevented from flowing from the second chamber to the first chamber, resulting in the rotorrotating in a second rotational direction relative to the stator and the cam timing beingadjusted in a second temporal direction, wherein the second temporal direction is opposite to the first temporal direction; iii. I/|aintaining the central solenoid valve in an open state until a desired degree of cam timing phasing is achieved; iv. Switching the central solenoid valve to a closed state, whereby fluidcommunication between the first chamber and the second chamber is prevented and the desired degree of cam timing phasing is maintained.
    These methods provides a simple, reliable way of controlling cam phasing, requiringcontrolling of only two on/off solenoids to provide phasing in either direction, or holding of the current phasing.
    According to a further aspect an internal combustion engine comprising a variable cam timingphaser arrangement as described above, and/or an integrated valve unit for a variable cam timing phaser arrangement as described above, is provided.
    According to yet a further aspect of the invention, a vehicle comprising a variable cam timingphaser arrangement as described above, and/or an integrated valve unit for a variable cam timing phaser arrangement as described above, is provided.
    BRIEF DESCRIPTION OF THE DRAWINGS Fig.1illustrates schematically one embodiment of a variable cam timing phaser arrangement according to the present disclosure. 12Fig. 2a illustrates schematically an integrated valve unit for use as a component of a variable cam timing phaser arrangement according to the present disclosure.
    Fig. 2b illustrates schematically a first flow path in an integrated valve unit according to the present disclosure.
    Fig. 2c illustrates schematically a second flow path in an integrated valve unit according to the present disclosure.
    Fig. 3 shows a process chart for a method for contro|ing the timing of a camshaft in an internal combustion engine according to the present disclosure.
    Fig. 4 illustrates schematically a vehicle comprising an internal combustion engine comprising a variable cam timing phaser arrangement according to the present disclosure.
    DETAILED DESCRIPTION The present invention is based on the realisation that cam torque actuated cam phasing can beachieved by utilising control assembly comprising a centrally-mounted on/off piloted valvetogether with a centrally mounted on/off solenoid valve, instead of the multi-positional spoolvalve known in the prior art. With a combination of two separately regulated on/off valves,together with appropriately positioned check valves, fluid flow can be controlled to advance,retard or hold the camshaft timing, using only simple, robust components. No multi-forceactuators, such as variable force solenoids or pressure regulator valves are required since nomulti-positional regulation is required. The two control valves can be integrated into a single unit and therefore require no more space than the multi-positional spool vales ofthe prior art.
    The cam timing phaser arrangement of the present invention comprises a rotor, a stator co- axially surrounding the rotor, and a control assembly.
    The cam phaser rotor is arranged to be connected to a camshaft of the internal combustionengine. This can be an intake valve camshaft, exhaust valve camshaft, or any other camshaft inthe engine such as a combined intake/exhaust camshaft. The rotor has at least one vane, but may preferably have a plurality of vanes, such as three, four, five or six vanes. Separate oil 13channels for channelling oil to and from the piloted valve of the control assembly are provided at each side of at least one of the vanes, but preferably at each side of each ofthe vanes.
    The stator is arranged for accepting drive force. This may for example be by connecting thestator to a cam sprocket, which takes up drive force from the crankshaft via the timing belt. Thestator may also be constructionally integrated with the cam sprocket. The stator co-axiallysurrounds the rotor and has at least one recess for accepting the at least one vane of the rotor.ln practice, the stator has the same number of recesses as the number of rotor vanes. Therecesses in the stator are somewhat larger than the rotor vanes, meaning that when the rotoris positioned in the stator with the vanes centrally positioned in the recesses, a chamber isformed at each side of each rotor. These chambers can be characterised as first chambers,rotating the rotor in a first direction relative to the stator when filled with hydraulic oil, andsecond chambers, rotating the rotor in a second direction relative to the stator when filled with hydraulic oil.
    The control assembly comprises a piloted valve, a remotely-located solenoid-controlledactuator for actuating the piloted valve, a first check valve arranged in a fluid path between thepiloted valve and the first chamber, a central solenoid valve, and a second check valve arranged in a fluid path between the central solenoid valve and the second chamber.
    Where valves are referred to as ”on/of " this refers to a valve having only two states: an openstate and a closed state. Such valves may however have more than two ports. For example, a3/2 way on/off valve has three ports and two states. Such a valve often connects two flow ports when open and connects one ofthe flow ports to a vent/exhaust port when closed.
    Where valves or valve sleeves are referred to as ”normally closed/open/on/off" this refers tothe state of the valve when non-actuated. For example, a normally open solenoid valve is heldin the open position when not actuated/energised, commonly using a return such as a springreturn. When the normally open solenoid valve is actuated/energised the solenoid acts with aforce sufficient to overcome the force of the return holding the valve open, and the valve istherefore closed. Upon de-actuation/de-energisation, the return returns the valve to the open State. 14Where components are stated to be in ”fluid communication” or flow is allowed or prevented”between” components, this flow is to be interpreted as not necessarily directional, i.e. flowmay proceed in either direction. Directional flow in a single direction is denoted as flow ”from” a component ”to” another component.
    The piloted valve is located centrally in the cam phaser, such as coaxially within the rotor orcamshaft, and rotates together with the rotor and camshaft. lt may be a separate componentor may be integrated with one or more further valves ofthe control assembly. The piloted valvemay be a 2/2 way on/off valve, i.e. a valve having two flow ports, i.e. a first and second port,and two positions (open or closed). The piloted valve is in fluid communication with an oilchannel leading to the first chambers at the first port and is in fluid communication with an oilchannel leading to the second chambers at the second port. Therefore, fluid communicationbetween the first and second chambers is established when the valve is open. The pilot valvealso has a pilot port connected to the pilot fluid feed. The switching of the on/off piloted valveis regulated by the pressure of the pilot fluid at the pilot port; the pressure of the pilot fluidbeing regulated by a remotely-placed solenoid actuator. The pilot fluid may be air, i.e. thepiloted valve may be pneumatically actuated. However, it is preferable that the pilot fluid ishydraulic oil since this considerably simplifies the system design, due to hydraulic oil alreadybeing used in the cam phaser arrangement. The pilot valve may be normally closed, i.e. beclosed when non-actuated. However it may also be normally open, i.e. open and allowing fluidcommunication between the first chamber and the second chamber when non-actuated. Thepiloted valve may be any suitable valve type known in the art, including but not limited to a poppet valve, sliding spool valve and rotary spool valve. The valve may have a return spring.
    The solenoid actuator regulates the pilot fluid pressure in order to actuate the piloted valve.This may be done by increasing the pressure to actuate the piloted valve by ”pushing”. Howeverthe piloted valve may also be actuated by a ”pulling” effect using decrease pilot fluid pressure.The solenoid actuator may be an on/off solenoid valve that increases fluid pressure byconnection to a source of fluid pressure, such as the main oil gallery if oil is used as the pilotfluid. lt can, for example be a 3-port, 2-position on/off solenoid valve being connected to an oilgallery at the inlet port, at the outlet port being connected to an oil channel leading to the pilotport ofthe pilot valve, and having a vent port for release of oil pressure from the channel leading to the pilot port when in the ”of” position. lt may normally be in the ”of” position when the solenoid is not actuated, and switch to the ”on” position upon activation of the solenoid. Thesolenoid valve may be any suitable valve type known in the art, including but not limited to apoppet valve, sliding spool valve and rotary spool valve. The use of a poppet valve virtually eliminates the risk for valve jam.
    The solenoid actuator may also be an oil-filled cylinder in fluid connection with the pilot port ofthe piloted valve. An on/off solenoid-actuated piston is provided in the cylinder. The solenoid-actuated piston may push down on the volume of oil in the cylinder upon actuation, leading toincreased pressure at the pilot port. Alternatively, the solenoid-actuated piston may retract inthe cylinder upon actuation, leading to decreased oil pressure at the pilot valve, and therefore a ”pull” effect.
    The solenoid actuator may be located remotely from the rotating components of the camphaser arrangement, such as on or in proximity to the camshaft bearings, or on another non- rotating component ofthe internal combustion engine.
    A first check valve is arranged in the fluid path between the piloted valve and the first chamber.This check valve may be a separate component or may be integrated with the pilot valve and/orother valves of the control assembly. The first check valve serves to allow only unidirectionalflow in the direction from the second chamber to the first chamber whenever the piloted valveis open. That is to say that the first check valve prevents flow from the first chamber to the second chamber.
    The central solenoid valve has a valve body located centrally in the cam phaser, such as coaxiallyin the rotor or camshaft, and this valve body rotates together with the rotor and camshaft. Thesolenoid actuating the central solenoid valve may be mounted externally to the rotor, in closeproximity to the rotor and centred on the rotation axis of the rotor. The solenoid is stationarywith respect to the rotating components ofthe cam phaser arrangement. The valve body of thecentral solenoid valve may be a separate discrete component, or it may be integrated with oneor more further valves ofthe control assembly. The central solenoid valve has a first port in fluidcommunication with the first chamber and a second port in fluid communication with thesecond chamber. lt has two states, an open position and a closed position. Whenever in theopen position it allows fluid communication between the second chamber and the first chamber, and in the closed position no fluid communication is allowed between the second 16Chamber and first Chamber via the central solenoid valve. The central solenoid valve may be a2/2 way on/off solenoid valve. lt may be normally closed, meaning that it is closed in the ”off”position and open in the ”on” position. Alternatively, it may be normally open. The centralsolenoid valve may be any suitable valve type known in the art, including but not limited to a poppet valve, sliding spool valve and rotary spool valve. The valve may have a return spring.
    A second check valve is arranged in the fluid path between the central solenoid valve and thesecond chamber. This check valve may be a separate component or may be integrated with thecentral solenoid valve and/or other valves of the control assembly. The second check valveserves to allow only unidirectional flow in the direction from the first chamber to the secondchamber whenever the central solenoid valve is open. That is to say that the second check valve prevents flow from the second chamber to the first chamber.
    The piloted valve, its solenoid actuator and the first check valve together serve to control a firstunidirectional fluid path from the second chamber to the first chamber. When the piloted valveis closed, no fluid flow via the piloted valve is possible. Whenever the piloted valve is opened,one-way fluid flow is allowed from the second chamber to the first chamber, but flow in the opposite direction via the piloted valve is prevented. ln a similar manner, the central solenoid valve and the second check valve together serve tocontrol a first unidirectional fluid path from the first chamber to the second chamber. When thecentral solenoid valve is closed, no fluid flow via the central solenoid valve is possible. Wheneverthe central solenoid valve is opened, one-way fluid flow is allowed from the first chamber to the second chamber, but flow in the opposite direction via the piloted valve is prevented.
    Therefore, the control assembly functions as two separate ”hydraulic ratchet" paths betweenthe first chamber and the second chamber, each ”hydraulic ratchet" path controlled by one ofthe central valves. lf the piloted valve is open and the central solenoid valve is closed, fluid canflow only from the second chamber to the first. Therefore, whenever periodic variations incamshaft torque result in the second chamber having higher fluid pressure than the firstchamber, fluid flows from the second to the first chamber. However, whenever the pressure inthe first chamber is higher than in the second, the opposite flow direction is prevented.Therefore, opening the piloted valve and closing the central solenoid valve will result in the rotor rotating in a first direction relative to the stator. lf the central solenoid valve is open and 17the piloted valve is closed, fluid can flow only from the first Chamber to the second. Therefore,whenever periodic variations in camshaft torque result in the first chamber having higher fluidpressure than the second chamber, fluid flows from the first to the second chamber. However,whenever the pressure in the second chamber is higher than in the first, the opposite flowdirection is prevented. Therefore, opening the central solenoid valve and closing the pilotedvalve will result in the rotor rotating in a second direction relative to the stator, the second direction being the opposite direction to the first direction. ln one embodiment, the piloted valve, central solenoid valve, first check valve and second checkvalve may be integrated into a single integrated valve unit. ln this case, the control assemblycomprises a single centrally located integrated valve unit, a remotely located solenoid actuatorfor actuating the piloted valve component (first valve sleeve) ofthe integrated valve unit, and acentral but stationary mounted solenoid for actuating the solenoid valve component of the integrated valve unit.
    The integrated valve unit will now be described in detail.
    A cylindrical housing comprising a cylindrical wall, a first end wall arranged to seal a first end ofthe cylindrical housing and a second end wall arranged to seal a second end of the cylindricalhousing. The cylindrical housing is preferably circle cylindrical and preferably has rotationalsymmetry along the longitudinal axis. The cylindrical wall of the housing has three sets of holesthrough the housing wall for allowing fluid communication with the housing. Each set of holescomprises at least one hole, but preferably two or more holes, such as four of more holes, orsix or more holes. The holes of each set are preferably evenly spaced around the circumferenceof the circular wall of the housing. Each hole through the housing may be circular, but it mayalso be elongated in either the radial direction or longitudinal direction of the housing, in relation to the longitudinal rotational symmetry axis ofthe housing.
    The first set of holes is located in proximity to the first end wall of the housing, the second setof holes is located in proximity to a middle portion of the cylindrical housing, and the third set of holes are located in proximity to the second end wall of the housing. 18Within the housing, a first valve seat is arranged between the first set of holes and the secondset of holes, and a second valve seat is arranged between the second set of holes and the third set of holes.
    A first valve member is arranged in the housing, on the side of the first valve seat closer to thefirst end wall of the housing. This valve member is normally seated on the first valve seat, thusforming a sea| and preventing flow from the first set of holes to the second set of holes.However, flow in the direction of from the second set of holes to the first set of holes will unseat the valve member and therefore flow in this direction is allowed.
    A second valve member is arranged in the housing, between the first valve seat and the secondvalve seat. The second valve member is normally seated on the second valve seat, forming asea| and therefore preventing flow from the second set of holes to the third set of holes.However, when subjected to flow from the third set of holes, the second valve member is displaced, allowing flow to the second set of holes.
    The first and second valve members may be any valve members known in the art, such as discvalve members or ball valve members. The check valves may be biased towards the normally seated position by any known means, including springs.
    The overall flow directions allowed by the housing together with the valve seats and valvemembers is therefore from the second set of holes to the first set of holes; and from the thirdset of holes to the second set of holes. The flow directions prevented are flow from the first setof holes to the second or third set of holes; or flow from the second set of holes to the third set of holes.
    Two valve sleeves are arranged outside of the housing and coaxially with the housing. The firstvalve sleeve is arranged in proximity to the first end ofthe housing. The first valve sleeve can bemoved between an open position and a closed position when subjected to altered external fluidpressure from a pilot fluid. The open position allows fluid flow through the first set of holes, andthe closed position prevents fluid flow through the first holes. Thus, the closed position preventsflow from the second or third set of holes to the first set of holes. The open/close function ofthe valve sleeve can be attained for example by having holes in the first valve sleeve corresponding to those ofthe first set of holes in the valve housing. When the holes in the valve 19sleeve are aligned with those in the valve housing, flow is allowed; when the holes are non-aligned flow is prevented. The first valve sleeve can be moved between the open and closedpositions by translational movement in a direction along the longitudinal axis of the housing.However, a rotational motion around the longitudinal axis is also conceivable as a method ofswitching between the two states. The first valve sleeve may be biased using for example a spring return member so that it is normally open. Alternatively, it may be normally closed.
    The second valve sleeve is arranged in proximity to the second end of the housing. The secondvalve sleeve can be moved between an open position and a closed position when subjected toan actuating force from a solenoid actuator. The open position allows fluid flow through thethird set of holes, and the closed position prevents fluid flow through the third holes. This canbe attained for example by having holes in the second valve sleeve corresponding to those ofthe third set of holes in the valve housing. When the holes in the valve sleeve are aligned withthose in the valve housing, flow is allowed; when the holes are non-aligned flow is prevented.The third valve sleeve can be moved between the open and closed positions by translationalmovement in a direction along the longitudinal axis of the housing. However, a rotationalmotion around the longitudinal axis is also conceivable as a method of switching between thetwo states. The second valve sleeve may be biased using for example a spring return member so that it is normally closed. Alternatively, it may be normally open.
    The second set of holes is never covered by a valve sleeve and therefore is always open to fluid communication.
    The valve housing and valve sleeves may be encompassed by an integrated valve enclosure thatholds the various parts in correct relation to each other and allows fluid connection to the firstand second chambers. The first set of holes and the third set of holes are arranged in fluidconnection with the first chamber, and the second set of holes is arranged in fluid connectionwith the second chamber. When arranged in this manner, the integrated valve unit acts in ananalogous manner to the non-integrated control assembly as described above. The first valvesleeve is analogous to the piloted valve and the second valve sleeve is analogous to the centralsolenoid valve. The check valve functions are performed by the valve housing, valve seats andvalve members. Having the first valve sleeve opened and the second valve sleeve closed allows unidirectional flow from the second chamber to the first, but prevents flow in the opposite direction. Having the second valve sleeve opened and the first valve sleeve closed allowsunidirectional flow from the first chamber to the second, but prevents flow in the opposite direction.
    The oil pressure may be maintained in the cam phaser system ofthe invention by connection toa source of oil pressure, such as the main oil gallery. For example, such connection points maybe arranged on the fluid channels leading from the first and/or second chambers to the pilotedvalve. Such connection points may also be arranged in conjunction with the solenoid actuator,for example as a connection to the inlet port of a solenoid valve (as previously mentioned), orin conjunction with an oil-filled cylinder. The channel(s) connecting to the source ofoil pressuremay be provided with a check valve(s) to prevent backflow of oil from the cam phaser assembly to the source of oil pressure.
    The cam phaser assembly may also be provided with a number of failsafe features. For example,a pressure-actuated lock pin may be arranged in at least one of the vanes of the rotor, togetherwith a corresponding recess in the stator for receiving the lock pin. The recess for receiving thelocking pin is located at a base position, i.e. either fully advanced or fully retarded. A torsionspring may be provided in order to bias the rotor towards the base position in the event ofsystem failure. However, the control assembly of the cam phaser may also be biased so thatone of the control valves is normally open and the other normally closed, meaning that in theevent of electrical failure ofthe solenoids, the rotor will be used to base position by cam torqueactuation. Therefore, no torsion spring is necessary. The lock pin is normally in the deployed(locking) position, and is actuated to the retracted (unlocked) position when the pressure in acomponent ofthe cam phaser arrangement exceeds a threshold pressure. For example, the lockpin may be in fluid connection with one or more channels leading from a chamber to the piloted valve.
    The means of controlling phasing using the variable cam timing phaser arrangement of thepresent disclosure is the same regardless of whether the control assembly comprises separatevalve components or an integrated valve unit. When camshaft phasing is desired, one of thecontrol valves is open and the other is closed in order to allow unidirectional flow from onechamber to the other. The periodic variation in torque acting on the camshaft results in periodic fluctuations in each of the two chambers relative to the other chamber. When the pressure 21difference acts in the allowed direction of flow, fluid will flow between the two chambers in theallowed direction. When the pressure difference acts in the opposite direction the controlassembly will act as a check valve and prevent flow. Thus, the rotor will gradually be rotatedrelative to the stator in the desired direction and the camshaft timing will be altered. So, forexample opening the piloted valve and closing the central solenoid valve will rotate the rotor ina first direction relative to the stator, whereas closing the piloted valve and opening the centralsolenoid valve will rotate the rotor in a second direction relative to the stator, wherein thesecond direction is opposite to the first direction. lf holding of the phasing is desired, both thepiloted valve and the central solenoid valve are closed and fluid if therefore prevented from flowing in both directions between the first chamber and the second chamber.The invention will now be illustrated with reference to the figures.
    Figure 1 shows one embodiment of the disclosed variable cam timing phaser arrangement. Acamshaft 1 rests on camshaft bearing 3. At the end ofthe camshaft 3 is a cam sprocket 5. Fixedto the cam sprocket is a stator 7. Co-axially arranged within the stator is a rotor 9. The rotor 9 isfixed to the end of the camshaft 1. The stator 7 and vanes (not shown) of the rotor 9 togetherform at least one first chamber 11 and at least one second chamber 13. By varying the oilquantity to and from the first 11 and second 13 chambers, the angle of the rotor 9 relative tothe stator 7 can be varied. Since the rotor 9 is fixed to the camshaft 1 and the stator 7 is fixedto the cam sprocket 5, the angle between the camshaft 1 and cam sprocket 5 is also varied and the valve timing of the internal combustion engine is altered.
    A control assembly is used to regulate the fluid flow to and from the first chamber 11 and secondchamber 13. The control assembly comprises a 2/2 way fluid-pressure piloted valve 15. Thepiloted valve 15 is located centrally in an end of the camshaft 1 in proximity to the rotor 9. Afirst port of the piloted valve 15 is in fluid connection with the first chamber 11 via a first oilchannel 17, and a second port ofthe piloted valve 15 is in fluid communication with the secondchamber 13 via a second oil channel 19. A first check valve 21 is arranged in the first oil channel17 in order to allow flow from the piloted valve 15 to the first chamber 11, but to prevent flow in the opposite direction.
    A pilot oil channel 23 leads from the pilot port of the pilot valve 15 to an outlet port of a 3/2 way on/off solenoid valve 25. The solenoid valve 25 is located on the cam bearing holder. The 22inlet port of the solenoid valve 25 is connected to a source of oil pressure 27 such as the mainoil gallery, and the remaining port of the solenoid valve 25 is a vent port. Oil refill channels 29,31 leading from the source of oil pressure 27 adjoin the first oil channel 17 and second oilchannel 19 respectively. Each ofthe oil refill channels 29, 31 is fitted with a check valve (33, 35) preventing oil backflow from the first and second oil channels 17, 19.
    A central 2/2 way solenoid valve 37 is arranged having a valve body 37 located centrally withinthe rotor 9, and an external stationary solenoid 43 to control the valve body. A first port of thecentral solenoid valve 37 is in fluid connection with the first chamber 11 via a third oil channel39, and a second port ofthe central solenoid valve 37 is in fluid communication with the secondchamber 13 via a fourth oil channel 41. A second check valve 44 is arranged in the fourth oilchannel 41 in order to allow flow from the central solenoid valve 37 to the second chamber 13, but to prevent flow in the opposite direction.
    The piloted valve 15 is open when not actuated by increased fluid pressure and the solenoidvalve 25 is closed (leads the pilot oil channel 23 to vent) when not actuated. The central solenoidvalve 37 is closed when not actuated. Thus, when solenoid valves 25 and 35 are not energised,oil can flow from the second chamber 13 to the first chamber 11, but not from the first chamber11 to the second chamber 13. Thus, this mode acts both a phasing mode in a first direction, aswell as a failsafe mode moving the rotor to base position in the event that the solenoids of thesolenoid valves 25 and 35 fail. ln a second mode, remote solenoid valve 25 is energised, resultingin the piloted valve 15 being closed, and central solenoid valve 37 is not energised and thereforeclosed. ln this mode, no oil flow between the chambers is possible and the phasing is thereforeheld. ln a third mode, remote solenoid valve 25 is energised, resulting in the piloted valve 15being closed, and central solenoid valve 37 is energised and therefore open. Thus, in this mode,oil can flow from the first chamber to the second chamber and this mode therefore providesphasing in a second direction opposite to the first. As previously noted, the central solenoidvalve 37 rotates together with the rotor 9 and camshaft 1, whereas the solenoid 43 controllingthe valve 37 does not rotate, i.e. is stationary. This means that there is sliding contact betweenthe armature of the solenoid 43 and the central solenoid valve 37. However, the armature ofthe solenoid 43 of the central solenoid valve 37 need only be in contact with the valve 37 whenever phasing in the second direction is required, meaning that the sliding contact is 23minimal in duration as compared to prior art solutions where sliding contact is required to obtain a phasing holding mode.
    Figure 2 shows an integrated valve unit according to the present disclosure. Figure 2a shows theintegrated valve unit in the non-actuated state. The valve unit comprises a valve housing 101having a cylindrical wall 103, a first end wall 105 at a first end ofthe housing 101, and a secondend wall 107 at a second end of the housing 101. A first set of holes 109 through the cylindricalwall 103 is provided in proximity to the first end wall 105. A second set of holes 111 through thecylindrical wall 103 is provided in proximity to a middle portion of the cylindrical wall 103. Athird set of holes 113 through the cylindrical wall 103 is provided in proximity to the second endwall 107. A first valve seat 115 is located in the housing 101 between the first set of holes 109and the second set of holes 111. A second valve seat 117 is located between the second set ofholes 111 and the third set of holes 113. A first spring-biased ball valve member 119 is arrangedin the housing 101 to be normally seated on the first valve seat 115. A second spring-biased ballvalve member 121 is arranged to be normally seated on the second valve seat 117. A first valvesleeve 123 is arranged to co-axially surround the first end of the housing 101. The first valvesleeve 123 allows flow through the first set of holes 109 when in a first position and preventsflow through the first set of holes whenever in a second position. The first valve sleeve isnormally in the open position and is moved to the closed position by increased oil pressure fromthe remote solenoid actuator 25 (not shown). A second valve sleeve 125 is arranged to co-axiallysurround the second end ofthe housing 101. The second valve sleeve 125 prevents flow throughthe third set of holes 113 when in a first position and allows flow through the third set of holes113 whenever in a second position. The third valve sleeve is normally in the first (closed) position and is moved to the second (open) position by solenoid 43 (not shown).
    The first set of holes 109 and third set of holes 113 are arranged in fluid communication withthe first chamber 11 (not shown). The second set of holes is arranged in fluid communication with the second chamber 13 (not shown).
    Figures 2b and 2c show the fluid flow paths for rotating the rotor 9 relative to the stator 7 in both directions. The flow paths are indicated with arrows.
    Figure 2b shows the flow path whenever the first valve sleeve 123 is non-actuated (open) and the second valve sleeve 125 is non-actuated (closed). Whenever the first valve sleeve is open, 24and the second valve sleeve is closed, oil may flow from the second chamber 13 to the firstchamber 11 via the second set of holes 111 and first set of holes 109. The reverse flow directionis checked by ball valve member 119 and therefore flow from the first chamber 11 to the secondchamber 13 is prevented. Thus, a ”hydraulic ratchet" effect, allowing unidirectional flow in a first direction is obtained.
    Figure 2c shows the flow path whenever the first valve sleeve 123 is actuated (closed) and thesecond valve sleeve 125 is actuated (open). Whenever the first valve sleeve is closed, and thesecond valve sleeve is open, oil may flow from the first chamber to the second chamber via thethird set of holes 113 and second set of holes 111. The reverse flow direction is checked by ballvalve member 121 and therefore flow from the second chamber 13 to the first chamber 11 isprevented. Thus, a ”hydraulic ratchet" effect, allowing unidirectional flow in a second direction opposite to the first direction is obtained.
    When both valve sleeves 123, 125 are closed (not shown), no flow is possible between the first chamber 11 and second chamber 13, and therefore cam phase holding is achieved.
    Figure 3 shows a process flow diagram for a method of controlling the timing of a camshaft inan internal combustion engine comprising a variable cam timing phaser arrangement as disclosed. ln step i. both the piloted valve and the central solenoid valve are closed and the cam phaser is therefore provided in a holding mode. ln step ii. either one of the piloted valve or the central solenoid valve is opened to allowunidirectional flow between the first chamber and the second chamber in a single direction,wherein flow in the reverse direction is prevented by the check valve functionality ofthe control assembly. ln step iii. the valves are maintained in the same state as in step ii. for the required period of time for the desired degree of cam phasing to be obtained. ln step iv. both the central solenoid valve and the piloted valve are closed to prevent fluidcommunication between the first and second chambers and to set the cam phaser to a phase holding state.
    The present invention also relates to an internal combustion engine and a vehicle comprising avariable cam timing phaser arrangement as described above. Figure 4 shows schematically aheavy goods vehicle 200 having an internal combustion engine 203. The internal combustionengine has a crankshaft 205, crankshaft sprocket 207, camshaft (not shown), camshaft sprocket209 and timing chain 211. The variable cam timing phaser arrangement 201 is located at therotational axis of the cam sprocket/camshaft. An engine provided with such a variable camtiming phaser arrangement has a number of advantages such as better fuel economy, lower emissions and better performance as compared to a vehicle lacking cam phasing.
    权利要求:
    Claims (15)
    [1] 1. CLAll/IS 26
    [2] 2. A variable cam timing phaser arrangement (201) for an internal combustion enginecomprising: a rotor (9) having at least one vane, the rotor (9) arranged to be connected to acamshaft (1); a stator (7) co-axially surrounding the rotor (9), having at least one recess for receivingthe at least one vane of the rotor (9) and allowing rotational movement of the rotor(9) with respect to the stator (7), the stator (7) having an outer circumference arrangedfor accepting drive force; wherein at least one vane divides the at least one recess into an first chamber (11) anda second chamber (13), the first chamber (11) and the second chamber (13) beingarranged to receive hydraulic fluid under pressure, wherein the introduction ofhydraulic fluid into the first chamber (11) causes the rotor (9) to move in a firstrotational direction relative to the stator (7) and the introduction of hydraulic fluidinto the second chamber (13) causes the rotor (9) to move in a second rotationaldirection relative to the stator (7), the second rotational direction being opposite thefirst rotational direction; and a control assembly for regulating hydraulic fluid flow from the first chamber (11) tothe second chamber (13) or vice-versa; characterised in that the control assembly comprises: a piloted valve (15) located centrally within the rotor (9), the piloted valve (15)comprising a pilot port, a first flow port in fluid communication with the first chamber(11), and a second flow port in fluid communication with the second chamber (13),wherein the piloted valve (15) is switchable between an open state and a closed stateby regulation ofthe pressure of a pilot fluid at the pilot port, wherein in the open statethe piloted valve (15) allows fluid communication between the first chamber (11) andsecond chamber (13), and in the closed state the piloted valve prevents fluidcommunication between the first chamber (11) and the second chamber (13), a first check valve (21) arranged in a fluid path between the piloted valve (15) and the first chamber (11), the first check valve (21) arranged to allow flow from the piloted 27 valve (15) to the first Chamber (11), but to prevent flow from the first chamber (11) tothe piloted valve (15); a solenoid-controlled actuator (25) located remotely from the rotating components ofthe variable cam timing phaser arrangement and in fluid communication with the pilotport of the piloted valve, the solenoid-controlled actuator (25) having at least twostates, a primary state and a secondary state, wherein the solenoid-controlledactuator (25) is arranged to switch the piloted valve (15) from the open state to theclosed state when the solenoid-controlled actuator (25) switches from the primarystate to the secondary state, and wherein the solenoid-controlled actuator (25) isarranged to switch the piloted valve (15) from the closed state to the open state whenthe solenoid-controlled actuator (25) switches from the secondary state to theprimary state, by regulating the pressure of the pilot fluid at the pilot port; a central solenoid valve having a valve body (37) arranged co-axially within the rotor(9) and/or camshaft (1), the central solenoid valve (37) comprising a first flow port influid communication with the first chamber (11) and a second flow port in fluidcommunication with the second chamber (13), wherein the central solenoid valve (37)is switchable between a closed state preventing fluid communication between thefirst chamber (11) and second chamber (13) and an open state allowing fluidcommunication between the first chamber (11) and the second chamber (13); and a second check valve (44) arranged in a fluid path between the central solenoid valve(37) and the second chamber (13), the second check valve (43) arranged to allow flowfrom the central solenoid valve (37) to the second chamber (13), and to prevent flowfrom the second chamber (13) to the central solenoid valve (37).
    [3] 3. A variable cam timing phaser arrangement according to claim 1, wherein the hydraulicfluid and/or pilot fluid is hydraulic oil.
    [4] 4. A variable cam timing phaser arrangement according to any one of claims 1-2, whereinthe piloted valve (15) is a 2/2 way on/off valve, arranged to be normally in the openstate, and actuated by increased fluid pressure at the pilot port to switch to the closedstate.
    [5] 5. A variable cam timing phaser arrangement according to any one of claims 1-3, whereinthe solenoid-controlled actuator (25) is a 3/2 way solenoid valve having an inlet port in fluid communication with a source of increased fluid pressure (27), an outlet port 28 in fluid communication with the pilot port of the piloted valve, and a vent port,wherein the primary state of the 3/2 way solenoid valve is a de-energised statepreventing fluid communication from the source of increased fluid pressure (27) tothe pilot port ofthe piloted valve (15) and allowing fluid communication from the pilotport of the piloted valve (15) to the vent port, and wherein the secondary state of the3/2 way solenoid valve is an energised state allowing fluid communication from thesource of increased fluid pressure (27) to the pilot port of the piloted valve (15) andactuating the piloted valve (15).
    [6] 6. A variable cam timing phaser arrangement according to any one of claims 1-3, whereinthe solenoid-controlled actuator is a solenoid-driven piston arranged in a cylinder, thecylinder being arranged in fluid communication with the pilot port of the piloted valve(15), wherein in the primary state the solenoid-driven piston is in a retracted positionrelative to the cylinder, and wherein in the secondary state the solenoid-driven pistonis actuated and moved to an extended position relative to the cylinder, whereby thepressure of the fluid at the pilot port of the piloted valve (15) is increased and thepiloted valve (15) is actuated.
    [7] 7. A variable cam timing phaser arrangement according to any one of the previousclaims, wherein the central solenoid valve (37) is a 2/2 way on/off solenoid valvearranged to be normally in the closed state, and actuated by energising the solenoid(43) to switch to the open state.
    [8] 8. A variable cam timing phaser arrangement according to any one of the previousclaims, wherein a source of increased fluid pressure (27) is arranged in fluidcommunication with the first chamber (11) and the second chamber (13) via a firstrefill channel (29) and a second refill channel (31), the first refill channel (29) andsecond refill channel (31) each having a check valve (33, 35) arranged to prevent fluidflow from the first chamber (11) or second chamber (13) to the source of increasedfluid pressure (27).
    [9] 9. A variable cam timing phaser arrangement according to any one of the previousclaims, wherein the piloted valve (15), the central solenoid valve (37), the first checkvalve (21) and the second check valve (44) are integrated into a single integrated valve unit arranged co-axially with the rotor.
    [10] 10. 29 An integrated valve unit for a variable cam timing phaser arrangement, comprising:A cylindrical housing (101) comprising a cylindrical wall (103), a first end wall (105)arranged to seal a first end ofthe cylindrical housing (101) and a second end wall (107)arranged to seal a second end ofthe cylindrical housing (101), wherein the cylindricalwall of the housing comprises a first hole (109) through the cylindrical wall (103) inproximity to the first end wall (105) of the housing, a second hole (111) through thecylindrical wall (103) in proximity to a middle portion of the cylindrical housing (103),and a third hole (113) through the cylindrical wall (103) in proximity to the second endwall (107) of the housing; a first valve seat (115) arranged in the housing (101) between the first hole (109) andthe second hole (111); a second valve seat (117) arranged in the housing (101) between the second hole (111)and the third hole (113); a first valve member (119) arranged to be normally seated on the first valve seat (115),the valve member (119) arranged to prevent flow from the first hole (109) to thesecond hole (111), but to allow flow from the second hole (111) to the first hole (109);a second valve member (121) arranged to be normally seated on the second valve seat(117), the second valve member (121) arranged to prevent flow from the second hole(111) to the third hole (113), and to allow flow from the third hole (113) to the secondhole (111); a first valve sleeve (123) arranged outside and co-axially with the housing (101) inproximity to the first end of the housing and arranged to be moveable between anopen position and a closed position when subjected to altered external fluid pressurefrom a pilot fluid, wherein the open position allows fluid flow through the first hole(109), and the closed position prevents fluid flow through the first hole (109); a second valve sleeve (125) arranged outside and co-axially with the housing inproximity to the second end of the housing and arranged to be moveable between aclosed position and an open position by the action of a solenoid (43), wherein theclosed position prevents fluid flow through the third hole (113), and the open positionallows fluid flow through the third hole (113). An integrated valve unit for a variable cam timing phaser arrangement according to claim 9, wherein the first hole (109) and the third hole (113) are each arranged to be
    [11] 11.
    [12] 12. in f|uid communication with a first Chamber (11) of the variable cam timing phaserarrangement (201), and the second hole (111) is arranged to be in f|uidcommunication with a second chamber (13) of the variable cam timing phaserarrangement (201). An integrated valve unit for a variable cam timing phaser arrangement according toany one of c|aims 9-10, wherein the first valve sleeve (123) is normally in the openposition and is moveable to the closed position when subjected to increased f|uidpressure, and wherein the second valve sleeve (125) is normally in the closed position and is moveable to the open position by energising the solenoid. A method for controlling the timing of a camshaft (1) in an internal combustion enginecomprising a variable cam timing phaser arrangement according to any one of c|aims1-8, the method comprising the steps: i. Providing the solenoid-controlled actuator (25) in a secondary state, therebyproviding the piloted valve (15) in a closed state, and providing the centralsolenoid valve (37) in a closed state; ii. Switching the solenoid-controlled actuator (25) to the primary state, therebyswitching the piloted valve (15) to an open state, whereby f|uid will flow fromthe second chamber (13) to the first chamber (11) due to periodic pressurefluctuations in the first chamber (11) and second chamber (13) caused bytorque acting on the camshaft, and whereby f|uid is prevented from flowingfrom the first chamber (11) to the second chamber (13), resulting in the rotor(9) rotating in a first rotational direction relative to the stator (7) and the camtiming being adjusted in a first temporal direction; iii. I/|aintaining the solenoid-controlled actuator (25) in the primary state until adesired degree of cam timing phasing is achieved; iv. Switching the solenoid-controlled actuator (25) to a secondary state, therebyswitching the piloted valve (15) to a closed state, whereby f|uid communicationbetween the first chamber (11) and the second chamber (13) is prevented and the desired degree of cam timing phasing is maintained.
    [13] 13.
    [14] 14.
    [15] 15. 31 A method for controlling the timing of a camshaft (1) in an internal combustion engine comprising a variable cam timing phaser arrangement according to any one of claims 1-8, the method comprising the steps: Providing the solenoid-controlled actuator (25) in a secondary state, therebyproviding the piloted valve (15) in a closed state, and providing the centralsolenoid valve (37) in a closed state; Switching the central solenoid valve (37) to the open state, whereby fluid willflow from the first chamber (11) to the second chamber (13) due to periodicpressure fluctuations in the first chamber (11) and second chamber (13)caused by torque acting on the camshaft, and whereby fluid is prevented fromflowing from the second chamber (13) to the first chamber (11), resulting inthe rotor (9) rotating in a second rotational direction relative to the stator (7)and the cam timing being adjusted in a second temporal direction, wherein thesecond temporal direction is opposite to the first temporal direction;I/laintaining the central solenoid valve (37) in an open state until a desireddegree of cam timing phasing is achieved; Switching the central solenoid valve (37) to a closed state, whereby fluidcommunication between the first chamber (11) and the second chamber (13) is prevented and the desired degree of cam timing phasing is maintained. An internal combustion engine (203) comprising a variable cam timing phaser arrangement according to any one of claims 1-8, and/or an integrated valve unit for a variable cam timing phaser arrangement according to any one of claims 9-11. A vehicle (200) comprising a variable cam timing phaser arrangement according to any one of claims 1-8, and/or an integrated valve unit for a variable cam timing phaser arrangement according to any one of claims 9-11.
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    同族专利:
    公开号 | 公开日
    WO2017204710A1|2017-11-30|
    KR20190007045A|2019-01-21|
    US20200318503A1|2020-10-08|
    US10927719B2|2021-02-23|
    EP3464839A1|2019-04-10|
    EP3464839B1|2021-03-24|
    KR102144951B1|2020-08-14|
    SE541810C2|2019-12-17|
    CN109154213A|2019-01-04|
    BR112018073376A2|2019-03-06|
    CN109154213B|2021-06-08|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1650712A|SE541810C2|2016-05-24|2016-05-24|Variable cam timing phaser having two central control valves|SE1650712A| SE541810C2|2016-05-24|2016-05-24|Variable cam timing phaser having two central control valves|
    US16/301,949| US10927719B2|2016-05-24|2017-04-11|Variable cam timing phaser having two central control valves|
    PCT/SE2017/050358| WO2017204710A1|2016-05-24|2017-04-11|Variable cam timing phaser having two central control valves|
    EP17717903.3A| EP3464839B1|2016-05-24|2017-04-11|Variable cam timing phaser having two central control valves|
    KR1020187036288A| KR102144951B1|2016-05-24|2017-04-11|Variable cam timing phaser with two central control valves|
    BR112018073376-8A| BR112018073376A2|2016-05-24|2017-04-11|variable cam timing phaser having two central control valves|
    CN201780032365.4A| CN109154213B|2016-05-24|2017-04-11|Variable cam timing phaser with two central control valves|
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