• 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:
    In a hydrostatic drive system for a mobile work machine, in particular an industrial truck, with at least one pump (2) for a pressure medium, which supplies a single-work hydraulics (3) via a supply line (9) comprising at least one consumer with the pressure means, where through a bypass valve (24) the supply line (9) is connectable to a heat exchanger (27) for cooling the pressure medium, the bypass valve (24) is designed as a hydraulically controlled control valve (25). Fig. 1 13
    公开号:SE1351533A1
    申请号:SE1351533
    申请日:2013-12-19
    公开日:2014-06-22
    发明作者:Markus Schwab
    申请人:Still Gmbh；
    IPC主号:
    专利说明:

    the useful volume flow, as the pressure medium volume flow over the return line of the heat exchanger device and flows through it.
    A disadvantage of the prior art is that the pressure medium flow flowing through the heat exchanger device, which determines the cooling effect and thus the cooling of the pressure medium, is subject to sharp oscillations and cannot be controlled appropriately according to cooling requirements. For this reason, it can lead to an overheating of the pressure medium.
    Furthermore, it is previously known to arrange a heat exchanger device in a return line for the working hydraulics of a working machine drawn to a tank. As a result, however, in the return line, for example during lowering operation of a lifting drive device of the working hydraulics, high flow losses at the heat exchanger device can occur and thus undesired effects on the lowering speed occur due to this additional standing pressure. In particular when lowering an unloaded load handler, the working speed of an industrial truck can thereby be affected.
    Furthermore, it is known to arrange a separate cooling circuit in parallel with the working hydraulics or similar hydraulic circuit as an additional pump circuit. A disadvantage of this technology, however, is the additional cost with an additional pump.
    From DE 10 2010 024 551 A1 a hydrostatic drive system is known, in which a heat exchanger device for cooling the pressure medium in a return line for a circuit pressure wave of a working hydraulics is arranged.
    The object of the invention is to provide a hydrostatic drive system, in which an overheating of the hydraulic fluid or the pressure medium can be avoided at a small cost and at the same time only small power losses occur when flowing through the heat exchanger device.
    This object is achieved by a hydrostatic drive system with the features according to claim 1.
    Advantageous embodiments appear from the subclaims. The object is provided according to the invention, by means of a hydrostatic drive system for a mobile work machine, in particular an industrial truck, with at least one pump for a pressure medium, which through a supply line supplies a working hydraulics with at least one consumer with the pressure means, where through a bypass valve the supply line is connectable to a heat exchanger , where the bypass valve is designed as a hydraulically controlled control valve. Advantageously this avoids that in a neutral circuit the pressure medium must be led over a control valve device of the working hydraulics, such as for instance a circuit pressure wave, in order to be able to cool the pressure medium. It does not lead to any effect on the lowering speed in the case of a lifting device such as working hydraulics due to. an additional standing pressure through the flow of the pressure medium over the heat exchanger device. In general, there is no effect on the functions of the working hydraulics, to the extent that a flow of the pressure medium with as low a resistance as possible is sought. A constant volume flow can advantageously be set over the bypass valve for cooling the pressure medium or the hydraulic fluid. In particular, a hydrostatic drive system for all hydraulically manoeuvrable functions of a mobile work machine can thus be realized with a single pump. This is particularly advantageous in the case of electrically driven industrial trucks, such as, for example, forklifts which are driven by a drive battery and electric motors as drive motors, since then only a single pump driven by an electric motor is required for the hydraulic fluid. In the same way, the hydrostatic drive system according to the invention is advantageous to use in industrial trucks driven by an internal combustion engine, in which an internal combustion engine drives a generator which drives electrically driven drive motors via a DC voltage intermediate circuit and converter. In this case, either further arranged at the internal combustion engine, or driven by a separate electric motor, the pump of the hydrostatic drive system can be driven and supply all hydraulically driven functions of the industrial truck with pressure medium. The design as a hydraulically controlled control valve between a locking position and an opening position provides a cost-effective and compact solution. In particular, the control of such a hydraulically controlled control valve can in itself take place through a control pressure line of the hydrostatic drive system. Advantageously, the bypass valve can be arranged in a branch line of the supply line and thereby, for example for the function of the bypass valve, a cost-effective proportional valve is used, whereby no additional flow resistance arises in the supply line when supplying, for example, a working hydraulics.
    Advantageously, the bypass valve is pressure controlled.
    This makes it possible to conduct pressure-controlled pressure medium to the heat exchanger and to provide a pressure-controlled bypass for the pressure medium cooling. Thereby, it is conceivable to design the bypass valve so that in a pressure range, in which the pressure medium is led to the heat exchanger, the cooling effect can be controlled by the supply amount of the pump.
    In an embodiment of the drive system, the control valve is designed as a pressure relief valve, which can be operated by a spring device in an opening position and the pressure sensed by the control pressure outlet upstream of the pressure relief valve can be operated in the direction of a locking position. In this case, the pressure relief valve is inverted, where it closes when a limit pressure is exceeded. This enables a variable adjustment of the cooling power during operation from 0% up to 100% of the maximum possible cooling power, provided the system pressure is kept below the limit pressure and for example via the pump speed of a constant pump or the setting of an adjustable pump, the volume flow is controlled by the heat exchanger. Only when the limit pressure at which the pressure-controlled bypass valve is set is exceeded does the bypass valve close.
    According to a preferred embodiment, the bias voltage of the spring device is set during the bias voltage of a circuit pressure wave, in particular a circuit pressure wave of the working hydraulics.
    When the pressure relief valve is set with its limit pressure to a pressure below the pressure given by the circuit pressure wave bias, the pump can be controlled according to the cooling demand and a bypass valve flow is present via the bypass valve in the heat exchanger before the circuit pressure wave opens. Instead of a discharge of the excess quantities over the circuit pressure wave to a tank, a circuit can instead be provided via the heat exchanger. In this case it is possible to design the hydrostatic drive system so that at a permissible limit temperature of the pressure medium the pump is controlled as required and runs at a speed or has a feed rate corresponding to a certain bypass volume flow required for cooling with coolant. In this case, the resistance of the bypass volume flow through the heat exchanger is still so small that the pressure relief valve does not close. If, on the other hand, the working hydraulics are operated, the volume flow of the pump increases significantly with the pump speed or in the case of an adjustable pump with high control. Thereby, the standing pressure over the heat exchanger increases and the pressure relief valve exceeds the limit pressure and closes. Thus, the entire volume flow is then available for the working hydraulics.
    According to an embodiment of the hydrostatic drive system, the bypass valve is volume flow controlled. This makes it possible to direct volume flow controlled pressure medium to the heat exchanger and to provide a volume flow controlled bypass for the pressure medium cooling.
    Advantageously, the control valve is designed as a flow control valve, which can be operated by a spring device in an opening position as well as by a control pressure outlet of the pressure generated upstream of the flow control valve. 10 15 20 25 30 35 Control valves, which are designed in this way, are also used as pipe break fuses. The control valve is set to the maximum bypass volume flow, which is required for the cooling of the pressure medium. If the volume flow exceeds, for example, when operating a working hydraulics, the bypass volume flow, which is required for this, the bypass valve closes completely and the entire total volume flow is available for the working hydraulics. This enables a variable adjustment of the cooling power during operation from 0% up to 100% of the maximum possible cooling power, as long as the supply current fed by the pump is kept below the maximum bypass volume flow of the flow control valve and, for example, the volume flow is controlled by the heat exchanger. adjustable pump. Only when the maximum bypass volume flow, on which the volume flow controlled bypass valve is set, is exceeded, the bypass valve closes.
    A choke device may be provided downstream of the second guide pressure outlet.
    In this way, the flow resistance, which is required for the volume flow control of the control valve, can be set.
    According to a preferred embodiment, the throttling device is arranged downstream of the control pressure outlet.
    In this way, the pressure depending on a volume flow can be set over the flow resistance, with which the control valve is operated against the spring device in a locking position.
    According to a preferred embodiment of the drive system, the pump is a constant pump and the pump can be switched off for a short time to operate the control valve in the opening position.
    After completion of a working function of the working hydraulics, the supply line must be relieved for a short time, so that the bypass valve designed as a hydraulically controlled control valve is opened again.
    This must be done both at the pressure relief valve, as well as at the design as a flow control valve. In the case of a constant pump, the speed is reduced so far or switched off for a short time, until the pressure in the supply line is sufficiently safe and falls sufficiently.
    The pump can be an adjustable pump and for operating the control valve in the opening position, the pump can be controlled to zero supply quantity for a short time.
    As previously described, by relieving the supply line, the control valve can open again. 10 15 20 25 30 35 For operating the control valve in the open position, the supply line can be relieved of pressure through a release valve.
    It is also conceivable to provide the relief of the supply line for opening the control valve through a release valve, which connects the supply line without pressure, for example where a pressure line is connected to a tank.
    Upstream of the bypass valve, a priority valve for feeding at least one present consumer can be arranged in the supply line, in particular a hydraulic control and / or brake.
    When the priority valve is arranged between pump and bypass valve, it can not in any operating position, especially in the event of a large cooling demand of the hydraulic fluid or pressure medium, lead to an effect on the pressure medium supply of the present consumer to be supplied, especially hydraulic control and / or brake.
    Further advantages and features of the invention are further elucidated in the embodiments shown in connection with the accompanying schematic figures. Of which Fig. 1 shows a first embodiment of a hydrostatic drive system according to the invention and Fig. 2 shows a second embodiment of a hydrostatic drive system according to the invention.
    Fig. 1 shows a hydrostatic drive system according to the invention designed as an Open-Center system, for example in a mobile work machine designed as an industrial truck in a schematic wiring diagram.
    The hydrostatic drive system comprises a pump 2 designed as a constant pump 1, which is driven in open circuit and is adapted for feeding a working hydraulics 3 and for example a hydraulic control 4 as the present consumer 5. The pump 2 sucks from a tank 6 over a filter 7 as well as a suction line 8 and feeds into a supply line 9, in which for the priority supply of the present consumer 5 a priority valve 10 is arranged. From the priority valve 10, a supply manifold 11 leads to said present consumer 5. The priority valve 10 is by means of a spring 12 and the load pressure of the present consumer 5 standing in a pressure sensor manifold 13 of the present consumer 5 in the direction of a supply line 9 with the supply manifold 11 for convenient supply of the present consumer 5 connecting position 14 operable. By means of the supply pressure in the supply manifold 11, the priority valve 10 is operable in the direction of a position 16, in which the supply line 9 is connected to the supply manifold 11 and a further part of the supply line 9 for simultaneous supply of the present consumer 5 and the working hydraulics. 3.
    The working hydraulics 3 may in the embodiment of the working machine as an industrial truck comprise, for example, a lifting drive device, a tilting drive device, a side slider device and one or more auxiliary consumers. The supply line 9 leads to a control valve block 17 as part of a control valve device 18 of the working hydraulics 3. The control valve block 17 comprises, for control of all consumers of the working hydraulics 3, a control valve designed as a road valve. In the control valve device 18 a circuit pressure wave 19 is arranged, which is arranged in a branch line 20 drawn from the supply line 9 to the tank. A tank line 15 enables return of the pressure medium into the tank 6 from the consumers or the control valve block 17. The circuit pressure wave 19 is operated by the sum of the forces in a load pressure branch line 21, the highest load pressure of the consumers of the working hydraulics 3 and a spring 22 in the direction of a locking position and of the supply pressure in the supply line 9 in the direction of a flow-through position.
    From the supply line 9, a branch line 23 departs between the priority valve 10 and the control valve block 17 of the working hydraulics 3, in which a bypass valve 24 is arranged. The bypass valve 24 is designed as a hydraulically controlled control valve 25. Through the bypass valve 24, pressure medium or hydraulic fluid can flow through a heat exchanger device 26 with a heat exchanger 27. The heat exchanger 27 delivers the heat of the pressure medium or hydraulic fluid to the environment and flows through air through an aerator 29. connected to the branch line 20 of the circuit pressure wave 19 and directs the pressure means over a filter 30 into the tank 6.
    The control valve 25 is designed as a pressure relief valve 31, which is operable by a spring device 32 in an opening position as shown and by a control pressure outlet 33 of the pressure of the pressure relief valve 31 in the direction of a locking position. Downstream of the control pressure outlet 33, a throttling device 34 is integrated in the control valve 25 so that it flows through in its opened position.
    Alternatively, a throttling device can also be arranged separately from the control valve 25.
    In the case of an industrial truck driven by an internal combustion engine, the pump 2 can be driven by the internal combustion engine, or even by its own electric motor, which is the rule in a battery-electrically driven industrial truck.
    The pressure relief valve 31 closes at a pressure below the pressure given by the spring bias of the spring 22 of the circuit pressure wave 19. Thereby the pump 2 can be controlled according to the cooling demand and a bypass valve flow is present via the bypass valve 24 in the heat exchanger 27. The working hydraulics 3 are operated 7, so the pump speed increases in the pump speed or in the case of an adjustable pump. In this way, the standing pressure in the throttling device 34 increases and the pressure relief valve 31 is closed above the pressure of the control pressure outlet 33. Thus, the entire volume flow for the working hydraulics 3 is available. Advantageously, it does not lead to an undesired effect on the consumer's mode of operation of the working hydraulics 3. In particular, in the case where a lifting device is arranged as a consumer, a reduction of the lowering speed is avoided. The solution according to the invention for cooling the hydraulic fluid works with a single pump 2 and produces only low power loss, when the pressure medium instead of over the circuit pressure wave 18 flows over the pressure limiting valve 31.
    In order to open the control valve 3 at the end of the work with the working hydraulics 3, it is necessary to leave the supply line 23 depressurised for a short time. This can be done with an electrically driven constant pump by switching it off for a short time, or with an adjustable pump, for example connected to an internal combustion engine, by setting the feed rate to zero for a short time.
    Fig. 2 shows a second embodiment of a hydrostatic drive system according to the invention.
    The components corresponding to the corresponding components in Fig. 1 are denoted by the same reference numerals. The hydrostatic drive system comprises the pump 2 designed as a constant pump 1, which is driven in an open circuit and is adapted to supply the working hydraulics 3 and, for example, the hydraulic control 4 as the present consumer.
    The pump 2 sucks out of the tank 6 over the filter 7 as well as the suction line 8 and feeds into the supply line 9, in which for priority supply of the present consumer 5 the priority valve 10 is arranged. From the priority valve 10, the supply branch line 11 leads to the present consumer 5. The priority valve 10 is maneuverable by means of the spring 12 and the load pressure of the present consumer 5 standing in the load pressure sensor branch line 13 of the present consumer 5 in the direction of a position 14 connected to the supply branch line 11 for suitable supply of the present consumer 5. .
    By means of the supply pressure standing in the supply branch line, the priority valve 10 is operable in the direction of the position 16, in which the supply line 9 is connected to the supply branch line 11 and a further part of the supply line 9 for simultaneous supply of the present consumer 5 and the working hydraulics 3.
    The working hydraulics 3 may in the design of the working machine as an industrial truck comprise, for example, a lifting drive device, a tilting drive device, a side slider device and one or more auxiliary consumers. The supply line 9 leads to the control valve block 17 as part of the control valve device 18 of the working hydraulics 3. The control valve block 17 comprises, for controlling each consumer of the working hydraulics 3, a control valve designed as a road valve. In the control valve device 18, the circuit pressure wave 19 is arranged, which is arranged from the branch line 20 drawn from the supply line 9 to the tank. , the highest load pressure of the consumers of the working hydraulics 3 and the spring 22 actuated in the direction of a locking position and of the supply pressure standing in the supply line 9 in the direction of a flow-through position.
    From the supply line 9, a branch line 23 departs between the priority valve 10 and the control valve block 17 of the working hydraulics 3, in which the bypass valve 24 is arranged. The bypass valve 24 is designed as a hydraulically controlled control valve 25. Through the bypass valve 24, pressure medium or hydraulic fluid can flow through the heat exchanger device 26 with the heat exchanger 27. The heat exchanger 27 emits the heat of the pressure medium or hydraulic fluid to the environment and flows through an aerator 28 of air.
    Outlet line 29 is connected to the branch line 20 of the circuit pressure wave 19 and leads the pressure means over the filter 30 into the tank 6.
    The control valve 25 is designed as a flow control valve 35, which of the spring device 32 can be operated in a shown opening position and through a control pressure outlet 33 of the pressure upstream of the flow control valve 35 can be operated in the direction of a locking position. In addition to the spring device 32, via a second control pressure outlet 36, the control valve 25 can be operated in an opening position by the pressure downstream of the flow control valve 35. Downstream of the control pressure sensor 33, a throttling device 34 is integrated in the control valve 25 so that it flows through in the open position. Alternatively, a throttling device can also be arranged separately from the control valve 25.
    In an industrial truck driven by an internal combustion engine, the pump 2 can be driven by the internal combustion engine, or even by its own electric motor, which is the rule in a battery-electrically powered industrial truck.
    The flow control valve 35 is set to maximum bypass volume flow, which is required for cooling the pressure medium. If the volume flow supplied by the pump 2 exceeds, for example, when operating the working hydraulics 3, the bypass volume flow required for the cooling, the bypass valve 24 closes completely and then the entire volume flow is available for the working hydraulics 3.
    In order to open the control valve 25 at the end of the work of the working hydraulics 3, it is also necessary in this embodiment to shorten the supply line 23 without pressure. This can be done, for example, in the case of the pump 2 designed as a constant pump 1, by switching it off for a short time, or in the case of an adjustable pump, for example connected to an internal combustion engine, by setting the feed rate to zero for a short time. 10
    权利要求:
    Claims (1)
    [1]
    A hydrostatic drive system for a mobile work machine, in particular an industrial truck, with at least one pump (2) for a pressure medium, which provides a working hydraulics (3) comprising at least one consumer with the pressure medium via a supply line (9). , where through a bypass valve (24) the supply line (9) is connectable to a heat exchanger (27) for cooling the pressure medium, characterized in that the bypass valve (24) is designed as a hydraulically controlled control valve (25). Hydrostatic drive system according to Claim 1, characterized in that the bypass valve (24) is pressure-controlled. Hydrostatic drive system according to claim 2, characterized in that the control valve (25) is designed as a pressure relief valve, which is operable by a spring device (32) in an opening position and by a control pressure outlet (33) of the upstream pressure relief valve (31) in a locked position direction. . Hydrostatic drive system according to Claim 3, characterized in that the bias voltage of the spring device (32) is set during the bias voltage of a circuit pressure wave (19), in particular a circuit pressure wave (19) of the working hydraulics (3). Hydrostatic drive system according to Claim 1, characterized in that the bypass valve (24) is volume flow controlled. Hydrostatic drive system according to claim 5, characterized in that the control valve (25) is designed as a flow control valve (35), which is operable by a spring device (32) in an open position as well as by a control pressure outlet (33) of the upstream flow control valve (35). in the direction of a locking position and in addition to the spring device (32) over a second control pressure outlet (36) through the pressure downstream of the flow control valve (35) in an opening position. Hydrostatic drive system according to Claim 6, characterized in that a throttling device is arranged downstream of the second control pressure outlet (36). Hydrostatic drive system according to one of Claims 3 to 7, characterized in that a throttling device (34) is arranged downstream of the control pressure outlet (33). Hydrostatic drive system according to one of Claims 1 to 8, characterized in that the pump (2) is a constant pump (1) and in that the pump (2) can be switched off for a shorter time for operating the control valve (25) in an opening position. Hydrostatic drive system according to one of Claims 1 to 8, characterized in that the pump is an adjustable pump and that the pump can be controlled for a shorter time to a supply quantity of zero for operating the control valve in the opening position. Hydrostatic drive system according to one of Claims 1 to 10, characterized in that for supplying the control valve in the opening position, the supply line can be relieved of pressure by a release valve. Hydrostatic drive system according to one of Claims 1 to 11, characterized in that upstream of the bypass valve (24) is a priority valve (10) arranged in the supply line (9) for supplying at least one present consumer (5), in particular a hydraulic control (4) and / or brake. 12
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    引用文献:
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    DE102010024551A1|2010-06-22|2011-12-22|Linde Material Handling Gmbh|Hydrostatic drive system|CN104329323B|2014-09-28|2016-08-24|常州联力自动化科技有限公司|A kind of wet brake and running motor combined cyclic cooling system|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    DE201210112932|DE102012112932A1|2012-12-21|2012-12-21|Hydrostatic drive system for mobile working machine, particularly industrial truck, has pump for pressure medium, which supplies working hydraulic system with load by pressure medium through feed pipe |
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