JP5489592B2 - Hydrostatic drive system - Google Patents

Description

  The present invention relates to a hydrostatic drive system with a pump with adjustable pumping volume, provided for supply to at least one consumer.

  In this type of drive system, the pumping volume of the pump is adjusted to the volumetric flow demanded by the consumer. If the consumer is controlled by a control valve, the consumer can thereby be operated with a small energy loss at the speed of motion defined for the control valve.

  In a load sensing drive system where the pump is operating in an open loop and a control valve is provided for consumer control, the pump pumping volume is controlled by the maximum load pressure and control pressure differential of the consumer being controlled. Has been. When controlling one or more control valves, the control valves each adjust a defined opening cross section. Until the pump pumping pressure is higher than the maximum load pressure of the controlled consumer by a control pressure differential, the pump configured as a control pump will have a pumping volume of the pumping volume due to the maximum load pressure produced by the controlled consumer. It is adjusted in the direction of increase. This results in the required volumetric flow required by the consumer controlled by the appropriate opening cross section of the control valve being delivered by the pump.

  However, based on the control of the pump's pumping volume in relation to the maximum load pressure of the controlled consumer, the delayed response behavior of the pump's pumping volume control, and thus the introduction and consumption of movement by controlling the corresponding control valve A discernible delay is introduced between the start of movement generated by the device. This is because the load pressure for controlling the pump is not formed until the control valve is loaded in the open position. This is perceived by the operator as low dynamics of the drive system. If the consumer is loaded with a negative pressure or pulling load that supports the movement of the consumer, a further pressure drop occurs in the pump's pumping line after operation of the control valve. The pressure drop leads to a further delay in controlling the pumping volume of the pump, and thus to a more delayed response behavior of the pumping volume control of the pump, and thus to the low dynamics of the drive system.

  The object of the present invention is to improve the hydrostatic drive system described at the beginning to enable control of a consumer with little energy loss under high dynamics and high reliability. It is in.

  In order to achieve the above object, the hydrostatic drive system according to the present invention is such that the pump is formed as a pump capable of adjusting the pumping volume by hydraulic pressure, and the pumping volume adjusting device of the pump Based on the hydraulic pressure return signal that is continuously loaded in the increasing direction by the setting device and detects the pumping volume of the pump that has been pumped in excess, the pumping volume can be adjusted in the decreasing direction.

  Preferably, a circulating pressure balance is provided to detect the volume flow of the extra pumped pump, and the circulating pressure balance is arranged in a branch line connecting the pump's pumping line to the container. The circulating pressure balance is loaded by the maximum load pressure and spring of the controlled consumer in the direction of the shut-off position that interrupts the connection between the pressure line and the container, and the pressure balance is the pressure line It is characterized by being loaded by the pumping pressure of the pump in the direction of the flow position connecting the container to the container.

  Preferably, a throttling device is arranged downstream of the circulating pressure balance in the branch line, and the hydraulic pressure return signal is formed as a dynamic pressure signal read between the circulating pressure balance and the throttling device. It is characterized by.

  Preferably, the pumping volume adjusting device of the pump has an adjusting piston device, said adjusting piston device being operatively coupled to the pumping volume adjusting member of the pump, and the setting device comprising a pumping volume adjusting member, in particular an adjusting piston device. It is characterized in that it is formed by a spring that is continuously loaded in the direction of increasing the pumping volume and / or the setting device is formed by an adjusting pressure that is continuously loaded in the direction of increasing the pumping volume.

  Preferably, the regulating pressure line for guiding the regulating pressure is connected to the pumping line and / or the control pressure source of the pump, the regulating pressure line being connected to the control pressure chamber of the regulating piston device acting in the direction of increasing the pumping volume. It is characterized by being guided.

  Preferably, the regulating pressure line is connected to the selection valve device, in particular, the switching valve on the outlet side, and the selection valve device includes a control pressure line of the control pressure source and a branch line branching from the pumping line of the pump. It is characterized by being connected to the entrance side.

  Preferably, the hydraulic pressure return signal is guided by the adjusting piston device.

  Preferably, the return signal line branched off from the branch line between the circulating pressure balance and the throttle device is guided in the control pressure chamber of the regulating piston device which acts in the direction of reducing the pumping volume. Features.

  According to the present invention, the pump volume adjusting device of the pump, which is formed as a regulating pump configured simply, is continuously loaded in the direction of increasing the pumping volume based on the setting device, and detects the extra pumped volume flow of the pump On the basis of the hydraulic pressure return signal, it turns back in the direction of reducing the pumping volume and is thus controlled to the required volume flow required by the controlled consumer. This results in improved response behavior of the pump volume control and thus high dynamics of the drive system. This is because the setting device used to control the pumping volume of the pump is used before the operation of the consumer, and therefore the pump should be adjusted to increase the pumping volume before or simultaneously with the operation of the consumer. Because you can. By using a hydraulic pressure return signal to control the pump to the required volume flow required by the consumer and thus reduce losses, a sensor that is prone to failure in the drive system according to the present invention is not necessary. Absent. The sensor has a high possibility of failure when the drive system according to the present invention is used in a vehicle or a self-propelled working machine. Overall, therefore, the drive system according to the invention based on pump control with improved response behavior has high dynamics and low reliability with a high hydraulic return signal and high reliability. Furthermore, the pump has a simple structure with a small construction effort. This is because the load of the pumping volume adjusting device of the pump is determined by the setting device and the hydraulic pressure return signal for controlling the pumping amount. This is because no device is required.

  According to an advantageous configuration of the invention, the pump is operated in an open loop, and a circulating pressure balance is provided for detecting the volume flow of the extra pumped pump. The circulating pressure balance is arranged in a branch line connecting the pump pressure line to the container. The circulating pressure balance is loaded by the maximum load pressure and spring of the controlled consumer in the direction of the shut-off position that shuts off the connection between the pressure line and the container, and the flow position that connects the pressure line to the container It is loaded by the pumping pressure in the direction of. This type of circulating pressure balance located in the pump's pumping line will exceed the required volume flow of the controlled consumer, and thus the pump's volume flow that is pumped will be adequate for the consumer. In the case of an open loop drive system which can be operated by a simple control valve, it can be easily detected and guided to the container.

  According to another advantageous configuration of the invention, a throttling device is arranged in the branch line downstream of the circulating pressure balance, and a hydraulic pressure return signal is read between the circulating pressure balance and the throttling device. It is particularly advantageous if it is formed as a dynamic pressure signal. The excess pressure pumped volume flow is simply detected by the circulating pressure balance and a hydraulic dynamic pressure based on the volume flow can be generated by the throttle device. The dynamic pressure can be used as a hydraulic pressure return signal for request quantity control of a pump operated in an open loop.

  According to a further advantageous configuration of the invention, the pump volume control device of the pump comprises a control piston device. The adjusting piston device is operatively coupled to the pumping volume adjusting member of the pump. The setting device is formed by a spring in which the pumping volume adjusting member, in particular the adjusting piston device, continuously loads in the direction of increasing the pumping volume and / or the setting device in the direction of increasing the pumping volume. It is formed by adjusting pressure that is continuously applied. This type of mechanical-hydraulic regulating pump allows high dynamics of the drive system and does not require costly electrical or hydraulic regulators or control valves for pumping control and is therefore structurally It has a simple structure that requires little effort. The pumping volume adjusting device of the adjusting pump is continuously loaded in the direction of increasing the pumping amount by a spring and / or hydraulic adjusting pressure, and by a hydraulic pressure return signal based on the pumping amount of the extra pumped pump. Rotate back to meet the required amount required by the controlled consumer.

  The adjusting pressure line that guides the adjusting pressure that leads to the control pressure chamber of the adjusting piston device, acting in the direction of increasing the pumping volume, may be connected to the pumping line and / or the control pressure source of the pump. This provides a regulated pressure that continuously loads the pump in a direction that increases the pumping volume. Even if the pumping pressure of the pump decreases when controlling a consumer loaded with negative pressure, the dynamic pressure is high when the pump is swung outward in the direction of increasing the pumping volume by adjusting the pressure of the spring and the control pressure source. Can be guaranteed.

  The control pressure line is connected to the selection valve device, in particular, the switching valve on the outlet side, and is connected to the control pressure line of the control pressure source and the branch line branched from the pump pressure supply line on the inlet side. In this case, the load of the adjusting piston device due to the pumping pressure of the pump and the adjusting pressure of the control pressure source can be achieved simply by means of a further advantageous configuration of the invention.

  According to a further configuration of the invention, the hydraulic pressure return signal is guided to the adjusting piston device. This kind of direct return guidance of the return signal to the adjustment piston device, and thus the direct load of the adjustment piston device by the hydraulic pressure return signal, in particular in a mechanical-hydraulic adjustment pump with little construction effort. Allows the pump to swivel back to the pumped volume required by the consumer.

  According to yet another configuration of the invention, the return signal line branched from the branch line between the circulating pressure balance and the throttle device is used to control pressure of the adjusting piston device acting in the direction of reducing the pumping volume. Guided to the room.

It is the figure which showed the circuit of the drive system which concerns on this invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  In the drawing, a circuit diagram of a drive system according to the present invention is shown.

  The drive system 1 according to the present invention shown in FIG. 1 has a pump 2 capable of adjusting the pumping volume. The pump 2 is operated in an open loop. The pump 2 is coupled to the container 4 via a pipe 3 and is pumped through a pressure feed pipe 5. A control valve 7 is provided for controlling one or more consumers 6. The control valve 7 is configured as a directional control valve having a throttling action at an intermediate position. The control valve 7 is connected to the pressure feed line 5, the container line 9, and the pressure medium lines 8 a and 8 b guided to the consumer 6. When the control valve 7 is operated, the control valve 7 controls the connection between the pressure medium pipes 8a and 8b guided to the consumer 6, the pressure feed pipe 5 and the container pipe 9, and the pressure feed pipe is based on the control signal. The defined opening cross section from the line 5 to the pressure medium line 8a or 8b is released.

  The pump 2 is formed as a hydraulically adjustable pump. The pumping volume of the adjusting pump can be adjusted by the pumping volume adjusting device 10. Furthermore, an adjustment piston device 11 is provided. The adjustment piston device 11 has an adjustment piston 13 arranged in an adjustment cylinder 12. The adjusting piston 13 is operatively coupled to a pumping volume adjusting member 19 of the pumping volume adjusting device 10, for example, a swash plate capable of adjusting an inclination.

  The adjusting piston 13 of the adjusting piston device 11 can be continuously loaded in a direction in which the pumping volume is increased by a setting device 33 a formed as a spring 14.

  In addition or as an alternative to the spring 14, the adjustment piston 13 of the adjustment piston device 11 may be loaded in a direction in which the pumping volume is increased by the adjustment pressure formed by the setting device 33b. Further, the control pressure line 35 is guided to the control pressure chamber 15a of the control piston device 11 which acts in the direction in which the pumping volume increases. A spring 14 is similarly arranged in the control pressure chamber 15a. The regulating pressure line 35 can be coupled to the control pressure source 18, for example the supply pump or the control pressure pump of the drive system and / or the pumping line 5 of the pump 2. When the control pressure line 35 is coupled to the pressure feed line 5 and the control pressure source 18 of the pump 2 as in the illustrated embodiment, a selection valve device 36 formed as a switching valve, for example, may be provided. it can. The selection valve device 36 is coupled to the control pressure line 37 of the control pressure source 18 and the branch line 38 branched from the pressure feed line 5 of the pump 2 on the inlet side, and to the control pressure line 35 on the outlet side. It is connected.

  A circulation pressure balance 20 is arranged in a branch line 24 that couples the pressure-feed line 5 to the container line 9 and thus the container 4. The circulating pressure balance 20 is loaded by the controlled consumer and the highest load pressure of the spring 21 in the direction of the shut-off position 20a, which disconnects the connection between the pumping line 5 and the container 4, and the pumping line 5 is connected to the container. In the direction of the flow position 20 b connected to 4, it is loaded by the pumping pressure of the pump 2. In addition, a load pressure sensitive pipeline (LastDuckeldelining) 22 that leads the maximum load pressure of the consumer 6 to be controlled is connected to the control surface of the circulating pressure balance 20 acting in the direction of the shut-off position 20a. A pressure feed branch line 23 branched from the pressure feed line 5 is connected to the control surface of the circulating pressure balance 20 acting in the direction of the flow-through location 20b.

  In the branch line 24, a throttling device 30, for example, an orifice plate, is disposed between the circulation pressure balance 20 and the container line 9, and thus downstream of the circulation pressure balance 20. A hydraulic return signal can be generated by the throttle device 30 to control the pumping volume of the pump 2. Further, a return signal line 31 is connected to the branch line 24 between the circulation pressure balance 20 and the expansion device 30. A dynamic pressure signal is taken out as a hydraulic pressure return signal between the circulating pressure balance 20 and the throttling device 30 by the return signal line 31. The return signal line 31 is guided to the control pressure chamber 15b of the adjusting piston device 11 that acts in the direction of reducing the pumping volume.

  An electronic control device 25 is provided for controlling the control valve 7. The control device 25 is operatively connected on the input side to a setting device 26, for example a joystick. The control valve 7 has electrical operation devices 7a and 7b suitable for operation of the control valve 7, for example, magnets. The operation devices 7a and 7b are connected to the control device 25 on the output side. Instead of the electrical operating devices 7a, 7b, the control valve 7 may likewise be loaded hydraulically. An electrically controllable control pressure valve may be provided for producing a control pressure that loads the control valve 7. The control pressure valve is connected to the control device 25 on the output side. Furthermore, mechanical control of the control valve 7 is possible.

  Accordingly, the mechanically hydraulic adjustment pump of FIG. 1 is in the direction in which the adjustment pressure accumulated in the setting device 33a and / or the adjustment pressure line 35 formed as the spring 14, and thus the pumping volume is increased by the setting device 33b. Is continuously loaded. If the volumetric flow of the pump 2 exceeds the volumetric flow required by the controlled consumer 6, the circulating pressure balance 20 is forced by the force of the spring 21 by the pumping pressure of the pump 2 remaining in the pumping branch 23. The load is accumulated in the direction of the flow-through portion 20b against the maximum load pressure of the controlled consumer 6 accumulated in the load pressure transmission line 22. As a result, the required volume flow of the consumer 6 to be controlled is increased and consequently the volume flow of the pump 2 pumped in excess is guided to the container 4. A dynamic pressure based on the volume flow is formed in the expansion device 30. The dynamic pressure is accumulated in the return signal line 31 as a hydraulic pressure return signal. Thus, the circulating pressure balance 20 can easily detect the volume flow of the pump 2 exceeding the required amount of the consumer 6 to be controlled and thus the extra pumped pump 2 with respect to the throttling device 30. Based on the volume flow, a hydraulic pressure return signal formed as a dynamic pressure based on the volume flow can be formed in the return signal line 31. The hydraulic pressure return signal, which is accumulated in the return signal line 31 and detects the volume flow of the pump 2 pumped excessively, loads the pump 2 in the direction in which the pumping volume is reduced. As a result, the pumping volume of the pump 2 is adjusted to the required volume flow required by the controlled consumer 6.

  The drive system according to the present invention operates as follows.

  When the control valve 7 is not controlled, the pump 2 is loaded in the direction of increasing the pumping volume by the adjustment pressure accumulated in the spring 14 or the adjustment pressure line 35. The circulating pressure balance 20 is loaded to the through-flow portion 20b against the spring 21 by the pumping pressure of the pump 2 accumulated in the pumping line 5. As a result, a dynamic pressure signal based on the volume flow is formed on the upstream side of the expansion device 30. The dynamic pressure signal loads the pump 2 in a direction in which the pumped volume is reduced via the return signal line 31, so the pump 2 is loaded in the direction of the minimum pumped volume.

  The circulating pressure balance 20 is loaded in the direction of the shut-off position 20a by the load pressure of the consumer 6 accumulated in the load pressure line 22 when the consumer 6 is controlled and, consequently, the control valve 7 is operated. As a result, the return signal decreases in the return signal line 31, and the pump 2 is swung out in the direction of increasing the pumping volume by the adjustment pressure accumulated in the spring 14 or the adjustment pressure line 35. If the pump 2 pumps a volume flow that exceeds the required amount of the consumer 6 to be controlled, the circulating pressure balance 20 is again loaded in the direction of the flow-through point 20b when the consumer 6 is controlled. A hydraulic pressure return signal formed as a dynamic pressure signal is detected via the return signal line 31 to detect the volume flow of the pump 2 pumped excessively. The return signal is swung back in a direction that reduces the volume flow of the pump 2 (zurueckschwenken). As a result, the pumping amount of the pump 2 is adapted to the requirements of the consumer 6 which is easily controlled.

  Thus, for example, based on the control of the control valve 7 for the operation of the consumer 6 and the appropriate operation of the circulating pressure balance 20 in the direction of the shut-off position 20a, the hydraulic pressure return signal drops in the return signal line 31. In this case, the pump 2 is always swung out in the direction of increasing the pumping volume. Thereby, the high dynamics (Dynamik) of the drive system 1 is obtained. High dynamics of the drive system is obtained by the regulated pressure accumulated in the spring 14 and / or regulated pressure line 35 and the continuous loading of the pump 2 in the direction of increasing the pumping volume. It is felt between the operation of the regulation device 26 by the operator, and in particular between the introduction of the movement of the consumer 6 when the consumer is loaded with negative pressure and the start of the movement generated by the consumer 6. This is because such a time delay cannot occur.

  Due to the hydraulic signal accumulated in the return signal line 31, the return signal formed as a dynamic pressure signal causes the pump to be requested by the consumer 6 based on the volume flow which is excessive and exceeds the amount required by the consumer 6. Adjusted to the pumped flow. The pump 2 formed as a regulating pump of the drive system according to the invention has a hydraulic or electrical control valve / regulating valve and a return sensitive device corresponding to the swivel angle of the pumped volume adjusting device 10. ing. Thereby, the swinging behavior of the pump 2 is not influenced by electrical influences, for example, inaccurate electrical adjustment signals. Furthermore, the pump 2 has high dynamics. This is because the control pressure of the control pump 18 accumulated in the spring 14 and the adjustment pressure line 35 increases the pumping volume even when the pumping pressure of the pump 2 is disappearing due to a negative pressure in the consumer 2, for example. This is because the pump 2 is swung out.

  The drive system 1 according to the present invention has high dynamics of pump control and, consequently, pumping volume adjustment of the pump 2. Due to the hydraulic pressure return signal formed by the circulating pressure balance 20 and the throttling device 30, the pumping volume of the pump 2, which is formed as a simply configured regulating pump, is required by the controlled consumer 6. Sensors are not required for precise control over volume flow. As a result, the possibility of failure of the drive system 1 according to the present invention is small, and the drive system 1 has high reliability.

  Therefore, when the drive system according to the present invention is used in a vehicle, for example, a self-propelled work machine, particularly an excavator or a grass transporter, a reliable drive system can be provided. Furthermore, the processing output can be increased by the drive system.

  DESCRIPTION OF SYMBOLS 1 Drive system, 2 Pump, 3 Pipe line, 4 Container, 5 Pressure feed line, 6 Consumer, 7 Control valve, 7a, 7b Operating device, 8a, 8b Pressure medium pipe line, 9 Container line, 10 Pressure feed volume adjustment Device, 11 adjusting piston device, 12 adjusting cylinder, 13 adjusting piston, 14 spring, 15a, 15b control pressure chamber, 17 control pressure line, 18 control pressure source, 19 pumping volume adjusting member, 20 circulating pressure balance, 20a blocking position, 20b flow position, 21 spring, 22 load pressure sensitive pipeline, 23 pressure feed branch pipeline, 24 branch pipeline, 25 control device, 26 setting device, 30 throttling device, 31 return signal pipeline, 33a, 33b setting device, 35 control pressure line, 36 selection valve device, 37 control pressure line, 38 branch line

Claims (7)

In a hydrostatic drive system with a pump capable of adjusting the pumping volume provided to supply at least one consumer,
The pump (2) is formed as a pump capable of adjusting the pumping volume hydraulically, and the pumping volume adjusting device (10) of the pump (2) is continuously set in the direction of increasing the pumping volume (33a; 33b) are loaded by, and extra based on liquid pressure returning to the signal detecting the volume flow of the pumped by pump (2), Ri adjustable der in the direction of reducing the pumping volume,
A circulating pressure balance (20) and a throttling device (30) are arranged between the pumping line (5) of the pump (2) and the container line (9) from the consumer to the container (4). A branch connecting the pressure line (5) to the container (4) between the circulation pressure balance (20) and a throttling device (30) arranged downstream of the circulation pressure balance (20) The return signal pipe (31) branched from the pipe (24) acts in the control pressure chamber (15b) of the adjusting piston device (11) of the pumping volume adjusting device (10) acting in the direction of reducing the pumping volume. Hydrostatic drive system, characterized in that it is guided .   2. The hydrostatic drive system according to claim 1, wherein the pump (2) is operated in an open loop to detect the volume flow of the extra pumped pump (2). The circulating pressure balance (20) is disposed in a branch line (24) connecting the pumping line (5) of the pump (2) to the container (4), and the circulating pressure balance (20) due to the maximum load pressure and spring (21) of the consumer (6) controlled in the direction of the shut-off position (20a) which shuts off the connection between the pressure-feed line (5) and the container (4). The circulating pressure balance (20) is loaded by the pumping pressure of the pump (2) in the direction of the flow position (20b) connecting the pumping line (5) to the container (4). The hydrostatic drive system according to claim 1, Beam. Branch conduit (24) aperture Ri device (30) is positioned within the liquid-pressure returning to the signal is formed as a dynamic pressure signal is read between the diaphragm and the circulation pressure balance (20) (30) The hydrostatic drive system according to claim 2, wherein: Regulatory piston device (11) is operatively connected to the pump (2) pumping volume adjusting member (19), set up device (33a) pumping volume adjustment member (19), in particular the adjusting piston device (11), Adjusting pressure formed by the spring (14) continuously loading in the direction of increasing the pumping volume and / or the setting device (33b) continuously loading the adjusting piston device (11) in the direction of increasing the pumping volume The hydrostatic drive system according to claim 1, wherein the hydrostatic drive system is formed by:   The adjusting pressure line (35) for guiding the adjusting pressure is connected to the pumping line (5) and / or the control pressure source (18) of the pump (2), and the adjusting pressure line (35) increases the pumping volume. 5. Hydrostatic drive system according to claim 4, characterized in that it is guided in the control pressure chamber (15a) of the adjusting piston device (11) acting on   The control pressure line (35) is connected to the selection valve device (36), in particular to the switching valve, on the outlet side. The selection valve device (36) is connected to the control pressure line (37) of the control pressure source (18) and the pump. The hydrostatic drive system according to claim 4 or 5, wherein the hydrostatic drive system is connected to a branch pipe (38) branched from the pressure feed pipe (5) of (2) on the inlet side. .   7. The hydrostatic drive system according to claim 1, wherein the hydraulic pressure return signal is guided by an adjusting piston device (11).

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