• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    SUMMARY The invention relates to a pump (5) for high-pressure fuel injection for pressurizing fuel and feeding it for injection into an internal combustion engine, said pump (5) for high-pressure fuel injection having an inlet (6), at least one piston (9), and a suction channel (8) placed between the inlet (6) and the at least one piston (9), wherein at least a part of said suction channel (8) is thermally insulated from the remaining part of said pump (5) for high pressure fuel injection. The invention further relates to a fuel injection system, which comprises such a pump (5) for high-pressure fuel injection. Alternatively to, or in combination with the thermal insulation of the suction duct, a drain valve (12) can be arranged in connection with said suction duct (8) of the pump (5) for high-pressure fuel injection. (Fig. 2)
    公开号:SE534893C2
    申请号:SE1000875
    申请日:2009-07-21
    公开日:2012-02-07
    发明作者:Sergi Yudanov
    申请人:Volvo Lastvagnar Ab；
    IPC主号:
    专利说明:

    25 30 534 B93 2 level of unwanted vapor formation of the fuel to ensure the least possible system cost and complexity. Choosing an operating pressure for the system's fuel tanks and feed pressure section that is too low for the selected fuel could, for example, make the installation of fuel cooling devices necessary and would thus increase the cost and complexity of the entire system. On the other hand, trying to solve problems with fuel evaporation simply by designing the system for higher pressures would also result in more expensive and heavier design solutions.
    When considering the fuel temperature part of the problem, it is important to note that control of local fuel temperatures is as important as of the average temperature of the fuel supply and injection system. This is partly due to the fact that steam formation is usually faster than condensation and that a steam bubble once it has formed can travel a long way through the system to finally get to a place where you least want it, usually the suction port of a pump. If this pump is a high-pressure fuel injection pump that supplies high-pressure fuel to the internal combustion engine injectors, the result will be an immediate loss of engine power.
    To get rid of hot spots in the fuel supply and injection system, especially in the part of the system (ie the fuel supply pressure subsystem) which is intended to supply liquid fuel with the correct pressure to the inlet of the high pressure fuel injection pump, a forced recirculation of the fuel is arranged in the subsystem for fuel supply pressure. In this way, the feed pump of the fuel feed pressure subsystem delivers an excess flow of fuel (exceeding the amount of fuel currently needed for the combustion process in the internal combustion engine) which passes the high pressure fuel injection pump and, via a throttle or returns to the fuel line the feed pump of the fuel supply pressure system. The higher the excess fl fate of fuel, the less the risk of hot spots appearing where evaporation can take place. 10 15 20 25 30 534 893 3 This approach generally works well, but the possibilities of controlling the system for the forced recirculation to have full effect may be somewhat limited by the design of the high-pressure fuel injection pump. This applies in particular to the inlet-controlled type of multi-piston high-pressure fuel injection pumps that usually have a single inlet control valve (IMV) for pump flow control. The function of the IMV valve is to throttle the supply flow to the pistons when partial capacity is needed, by means of which control of the injection pressure is achieved. This type of high pressure fuel injection pump is widely used due to its relative simplicity compared to variable displacement pumps, which allow efficient control of fuel injection pressure without wasteful bypass of high pressure fuel accepted in some systems with fixed displacement pistons.
    When an inlet-controlled high-pressure fuel injection pump is used, the need to distribute the outflow from the single IMV valve of the high-pressure fuel injection pump to a plurality of pump pistons in the pump gives rise to a limitation for efficient fuel recirculation throughout the low pressure fuel feed pressure subsystem. at the high pressure fuel injection pump. In the resulting suction volume downstream of the IMV valve, the pressure would need to be lower than in the rest of the fuel supply pressure subsystem to provide high pressure outflow control from the high pressure fuel injection pump. To make matters worse, this suction volume would normally be located inside the high pressure fuel injection pump running at relatively high temperatures as it is located in the immediate vicinity of the internal combustion engine or even flange mounted directly on it. The combination of hot environments and a reduction in fuel pressure can, under certain conditions, cause uncontrolled evaporation of the fuel in the suction volume and subsequent interruption of the fuel supply.
    This phenomenon would be particularly prominent in situations where the internal combustion engine is hot and running under conditions of partial load where a relatively small throughput of fuel is required in the suction volume. In such a case, the turnover of fuel in the suction volume would be slow and the pistons of the high pressure fuel injection pump would also process any existing vapor bubbles more slowly compared to a situation where a large supply of fuel is required by the high pressure fuel injection pump. to the injectors of the internal combustion engine. One way to deal with this problem, which is known in the art, is to reduce the suction volume. This would increase the rate of fuel turnover in this suction volume for a given through fl waste of fuel and would therefore help to keep its temperature under control and would eventually also limit the amount of vapor bubbles formed in an uncontrolled manner that must be condensed by the pump pistons. However, the possibilities for such a reduction in suction volume are limited (i) by the need to ensure a sufficient flow area of the ducts from the IMV valve to the pistons of the high pressure fuel injection pump for full power conditions and (ii) by degree of packing and technical considerations, such as like for example. that the IMV valve can sometimes not be placed very close to the inlet of the pistons.
    SUMMARY OF THE INVENTION An object of the invention is to provide a pump for high pressure fuel injection, as well as a fuel injection system which includes a pump for high pressure fuel injection, which are less sensitive to vapor formation of the fuel.
    Another object of the invention is to provide a high pressure fuel injection pump and a fuel injection system which are suitable for processing high performance fuels, such as DME, for internal combustion engines.
    These objects are achieved by the features of the independent claims. The other claims and the description as well as the features show further advantageous improvements and embodiments of the invention.
    A general advantage of the invention is that it reduces the amount of vapor formation of the fuel to be pressurized by the high-pressure fuel injection pump and thus correspondingly the risk of the supply of pressurized fuel with the high-pressure fuel injection pump for injection into the combustion chamber. the fuel engine is reduced below the amount of fuel needed for the actual operation of the engine and at the same time improves the reliability and stability of the control of said supply of pressurized fuel for injection into the internal combustion engine.
    According to the present invention, there is provided a fuel injection system for an internal combustion engine, which system comprises a high pressure fuel injection pump for pressurizing fuel and feeding it for injection into the internal combustion engine, said high pressure fuel injection pump having an inlet (for receiving fuel from e.g. a fuel tank), at least one piston (which pressurizes the received fuel and feeds it to injectors for injection into the internal combustion engine) and a suction duct located between the inlet and the at least one piston (and thereby connecting the inlet of the high pressure fuel injection pump to the inlet port of the at least one the piston), and wherein a drain valve is arranged in connection with said suction channel of the pump for high-pressure fuel injection. Said drain valve is arranged in connection between the suction duct and a fuel return line connected to a fuel tank which retains the fuel which is collected in the fuel return line. This solution is particularly useful when a thermal insulation of the suction duct (or a part thereof) from the remaining part of said high-pressure fuel injection pump, according to the first aspect of the invention, is not possible or too complicated in its construction or too expensive to achieve .
    The tank is preferably the same fuel tank from which the fuel for the high-pressure fuel injection pump is delivered, thereby enabling efficient recirculation of fuel that is not treated by the at least one piston of the high-pressure fuel injection pump and consequently a corresponding reduction in average fuel consumption. In a preferred embodiment of the invention, the drain valve may be electronically controlled to open when it is likely that the suction duct contains fuel vapor, for example when a hot internal combustion engine must be started in very cold ambient conditions. . The drain valve can remain open for a relatively short period of time to allow the colder fuel to displace the fuel vapor back to the fuel return line.
    BRIEF DESCRIPTION OF THE DRAWINGS The present invention, together with the above and other objects and advantages, may best be understood from the following detailed description of preferred embodiments of the invention, but is not limited to these embodiments, wherein: Fig. 1 schematically shows a fuel injection system, not covered by the appended claims, with a high-pressure fuel injection pump equipped with an advantageous thermal insulation (in the form of a sleeve) of a part of the suction duct according to the present invention, Fig. 2 schematically shows an embodiment of the fuel injection system according to the present invention, with a pump for high-pressure fuel injection which is equipped with an advantageous thermal insulation (in the form of a sleeve) of a part of the suction duct according to the present invention and with an additional drain valve connected to a fuel return line.
    DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION In the figures, reference is made to like or similar parts with like reference numerals. The figures are only schematic representations and are not intended to depict specific parameters of the invention. Furthermore, the ur gures are only intended to depict typical embodiments of the invention and must therefore not be considered as limiting the scope of the invention.
    I fi g. 1 shows a fuel injection system, which, however, is not covered by the appended claims. The system comprises a fuel tank 1, a subsystem for low pressure fuel supply consisting of a feed pump 2, a throttle valve 10, a fuel supply line 13 and a fuel return line 4. The system further comprises a pump 5 for high pressure fuel injection with an inlet 6, an inlet control valve 7 (IMV), a suction duct 8 and, for example, three pistons 9, and a fuel injector 10 which injects the pressurized fuel into the internal combustion engine (not shown). The throttle valve 3, the IMV valve 7 and the injector 10 are controlled by a motor control system (EMS) (not shown). The visas clock shows a pump for high-pressure fuel injection with 3 pistons 9, which pistons 9 are phase-shifted in their pumping cycles. It is realized, however, that the choice of just 3 pistons is just one example. In fact, the number of pistons in such a pump may vary depending on the application and the particular conditions. Pumps with one, two, three, four, five, six, or even more than six pistons can be used in connection with the recovery. At least a part of the suction duct 8 is made in the form of a hole with a relatively large diameter in the pump 5 for high-pressure fuel injection and wherein a sleeve 11 made of a heat-insulating material is inserted into this hole.
    The sleeve 11 can cover the inside of the hole only on a certain part of a certain length (as shown as an example in fi guren), or the hole in its entire length. Alternatively, more than one sleeve could be inserted into the hole to cover the inside of the hole at certain (possibly separated) parts of certain (and possibly different) lengths.
    Furthermore, the sleeve (s), or any other thermal insulation, can also cover further parts of the suction duct 8 outside the hole, or the entire suction duct 8 between the IMV valve 7 and the inlet ports of the pistons 9.
    The inner diameter of the sleeve 11 is chosen so that the flow area of the sleeve 11 (the inner tube of the sleeve 11 characterized by the inner lameter) is large enough for the high pressure fuel injection pump 5 to reach its maximum nominal flow without restricting the inlet to the pistons 9, but otherwise a minimum to keep the total volume of the suction duct 8 as small as possible for good controllability of the fuel density in said suction duct 8.
    The fuel injection system in fi g. 1 operates as follows: the feed pump 2 sucks fuel from the fuel tank 1 and pressurizes it to a certain feed pressure. This supply pressure is supplied via the fuel supply line 13 to both the IMV valve 7 and the throttle valve 3. The throttle valve 3 is preferably controlled by the EMS system to achieve the required fuel supply pressure, while the feed pump 2 delivers a fuel flow exceeding the amount required for combustion power generation. This excess amount of fuel flow is recirculated via the fuel return line 4.
    The recirculated fuel flow thus established helps to keep the fuel temperature relatively even throughout the feed pressure circuit so that local hot spots and evaporation of fuel are likely to be avoided, to ensure stable fuel properties at the inlet of the IMV valve 7.
    The fuel at feed pressure is then released through the IMV valve 7 to the suction duct 8 and further to the inlet ports of the three pump pistons 9 which are phase shifted in their pumping cycles, as shown in the figure. During the downward stroke, the pistons 9 fill the fuel mass due to the EMS-controlled throttling of the IMV valve 7 and then pump it out of the high pressure fuel injection pump 5 and into the injector 10 to inject it into the internal combustion engine. The heat-insulating sleeve 11 slows down the rate of change of fuel properties (temperature, density, etc.) that occurs in the suction duct 8 due to heating of the hot body fuel of the high pressure fuel injection pump 5 and therefore reduces the risk of vapor formation in the suction duct 8 which may be high in critical operating conditions such as very low speed low speed operation immediately after high speed / high load operation of the internal combustion engine, when the internal combustion engine and pump body parts of the high pressure fuel injection pump 5 are at or near their temperature maximum and the supply of fresh and cold fuel to the suction duct 8 is at, or close to, its temperature minimum.
    Fig. 2 shows an embodiment of a fuel injection system according to the present invention. In addition to the system shown in fi g. 1 shows the system in fi g. 2 shows a drain valve 12 which is arranged on the suction duct 8, the outlet of the drain valve 12 being connected to the fuel return line 4. When the internal combustion engine and the high pressure fuel injection pump 5 are unusually hot but the fuel in the fuel tank 1 is relatively cold so the pressure in the fuel tank 1 is low and the feed pump 2 does not provide enough pressure to transfer the steam in the suction duct 8 in liquid form, opens the drain valve 12 for a limited time to drain the steam into the fuel return line 4 and allow filling of the suction duct 8 with fresh cooler (liquid ) fuel. This will, for example, help to start a warm engine in cold ambient conditions.
    The above description is provided by reference and the present invention may be embodied in many different versions and variants within the scope of the claims.
    权利要求:
    Claims (2)
    [1] 1. . A fuel injection system for an internal combustion engine, comprising a high-pressure fuel injection pump (5) for pressurizing fuel and delivering itfor injection into the internal combustion engine, said high-pressure fuelinjection pump (5) having an inlet (6), at least one plunger (9) and a suctionchannel (8) positioned between the inlet (6) and the at least one plunger(9). characterised in that a bleed valve (12) is connectively arranged at saidsuction channel (8) of the high-pressure fuel injection pump (5). . A fuel injection system according to claim 1, characterised in that said bleed valve (12) is connectively arranged between the suction channel (8) and afuel return line (4) connected to a fuel tank (1). . A fuel injection system according to any of the claims 1 or 2, characterised in that an inlet metering valve (llVlV) (7) is connectively arranged at the inletport (6) of the high-pressure fuel injection pump (5).
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    同族专利:
    公开号 | 公开日
    SE1000875A1|2011-01-22|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    WO2017155444A1|2016-03-07|2017-09-14|Scania Cv Ab|Fuel system for an internal combustion engine and a method to increase the vaporization temperature of a fuel used in a fuel system|
    EP2655856B1|2010-12-22|2019-10-02|Volvo Lastvagnar AB|Fuel injection system comprising a high-pressure fuel injection pump|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE0901014|2009-07-21|
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