CN107816463B

CN107816463B - Hydraulic drive system with multiple supply lines

Info

Publication number: CN107816463B
Application number: CN201710823199.1A
Authority: CN
Inventors: P.纳格尔; N.施特克; S.罗泽
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2016-09-14
Filing date: 2017-09-13
Publication date: 2021-12-10
Anticipated expiration: 2037-09-13
Also published as: DE102016217541A1; CN107816463A

Abstract

The invention relates to a hydraulic drive system having a first and at least one second supply line and a return line, wherein at least one actuator is provided, which can be connected in a fluid-exchange manner to at least one of the aforementioned supply lines and/or return line, optionally via an associated valve assembly, wherein the first supply line is connected to a first pump, wherein each second supply line (32) is connected to an associated second pump (22), wherein the return line (30) is connected to a tank (12). According to the invention, a drive device (40) is provided, which has a plurality of output shafts (51; 52) which are each in rotary drive connection with an associated first or second pump (21; 22), wherein the drive device (40; 41) is designed in such a way that energy can be exchanged between the output shafts (51; 52) via the drive device (40; 40').

Description

Hydraulic drive system with multiple supply lines

Technical Field

The invention relates to a hydraulic drive system.

Background

A hydraulic drive system is known from EP 791754B 1. The hydraulic drive system has a first and a second supply line and a return line. A plurality of actuators are connected to the aforementioned lines, which actuators can each be connected in a fluid-exchange manner to the aforementioned lines via associated valve assemblies. Each feed line is connected in decibels to the associated pump, the return line being connected to the tank.

Disclosure of Invention

The advantage of the hydraulic drive system according to the invention is that it is particularly energy-efficient (energieffizient). This applies in particular to an operating state in which a tensile (ziehend) load acts on one of the actuators. Furthermore, the different supply lines can be operated in a simple manner with different pressure levels, so that the energy efficiency is thereby also improved.

A drive device is provided, which has a plurality of output shafts, which are each in rotary drive connection with an associated first or second pump, wherein the drive device is designed such that energy can be exchanged between the output shafts via the drive device. In an operating state in which one of the pumps is operated as a motor, the energy supplied by this pump can thus be transmitted to the other pumps via the drive. This is done without appreciable losses in the form of waste heat (Abw ä rme).

The hydraulic drive system is preferably operated with a pressure fluid, which is most preferably a liquid; in particular hydraulic oil. Insofar as the pump is referred to within the scope of the present application, it should be understood that the pump operation is provided primarily in terms of time, wherein the motor operation is preferably also possible.

It can be provided that the drive device comprises at least one electric motor, which is connected in each case to an associated rotational speed adjustment device, so that its rotational speed can be adjusted. In EP 791754B 1, a pump with an adjustable displacement volume is provided. These pumps are typically operated at a constant rotational speed, for example at a rotational speed for which the respective internal combustion engine has an optimum efficiency. Within the scope of the invention, the proposed rotational speed regulation is used for energy-optimized operation of the hydraulic drive system. The at least one electric motor can be connected to a power supply network. The power supply network can be connected to a rechargeable battery. The rotational speed control device can be designed, for example, as a frequency converter.

It can be provided that the output shaft is a component of a mechanical distribution gear (verteileltriebe), wherein the distribution gear has as many rotational degrees of freedom as there are output shafts. By means of the distribution gear, energy can be exchanged mechanically between the drive shafts. In this case, a high efficiency can be achieved, so that the energy losses are low. Furthermore, the pressure regulation of the at least one second supply line can be dispensed with. The pressure there is coupled to the pressure in the first supply line in accordance with the transmission ratio of the distribution transmission. The distribution gear is, for example, a planetary gear. The planetary gear typically has two rotational degrees of freedom. A plurality of planetary gear mechanisms can be combined with one another for achieving more than two rotational degrees of freedom.

It can be provided that the distribution gear has a single input shaft which is in rotary drive connection with the associated first electric motor. Due to the distribution gear, no further electric motor is required for driving the at least two pumps, in addition to the first electric motor.

It can be provided that the output shaft is in each case in a rotary drive connection with an associated electric motor, wherein the electric motors are connected to a common power supply network, wherein energy can be exchanged between the electric motors at least indirectly via the power supply network. The rotational speeds of the different electric motors can thereby be adjusted independently of one another, so that the pressures in the different supply lines can be selected largely independently of one another. The power supply network can be connected to a rechargeable battery, the energy exchange mentioned taking place indirectly via the battery.

It can be provided that the first pump and the at least one second pump are connected in series between the first supply line and the return line, wherein the at least one second supply line is connected in each case between two of the pumps mentioned. At each pump, only a small pressure drop (Druckgef ä lle) thus occurs, which is less than the highest pressure in the first supply line. Correspondingly, the drive torque is small. In particular in combination with a distribution gear, a torque ratio is produced which can be achieved with a simple distribution gear.

Provision can be made for the first pump to have a constant or adjustable displacement volume, wherein the at least one second pump has a constant displacement volume. For a particularly cost-effective hydraulic drive system, all pumps, which are designed, for example, as external gear pumps, have a constant displacement volume. The first pump (with which the first supply line at the highest pressure is supplied) can have an adjustable displacement volume, wherein the first pump is designed, for example, as an axial piston pump. By adjusting the associated displacement volume, in particular when using the above-mentioned distribution gear, the ratio of the pressures in the first and second supply lines can be adjusted.

It can be provided that the first supply line is connected to a first pressure sensor, wherein the first pressure sensor and the at least one rotational speed regulation device are connected to a control device, wherein the control device is designed in such a way that a pressure in the first supply line, which pressure can be measured by means of the first pressure sensor, can be set to a predefined or predefinable setpoint value by adjusting the rotational speed of the at least one electric motor. In contrast, the pressure in the first supply line is electronically regulated, which is particularly cost-effective within the scope of the invention. Preferably, a control device is used, which comprises a programmable digital computer. This control device can be used without problems for further control tasks in the context of the hydraulic drive system.

A first pressure regulator having a first adjustable plate (Regelblende) can be provided, wherein the first supply line is connected to the tank via the first adjustable plate, wherein the first pressure regulator is designed in such a way that the pressure in the first supply line can be adjusted to a predefined or predefinable setpoint value by adjusting the first adjustable plate. As a result, the pressure in the first supply line can be regulated more quickly. A position sensor can be provided, by means of which the position of the first adjusting plate can be measured, wherein the position sensor is connected to the control device for transmitting a corresponding position value. As soon as a separate electric motor is assigned to each of the at least one second supply line, it is also possible to connect each of the at least one second supply line to an associated second pressure sensor, wherein the pressure regulation is carried out analogously to the first supply line.

It can be provided that a second pressure regulator with a second adjustable plate is provided, wherein the return line is connected to the tank via the second adjustable plate, wherein the second pressure regulator is designed in such a way that the pressure in the return line can be adjusted to a predefined or predefinable setpoint value by adjusting the second adjustable plate. By suitable adjustment of the pressure setpoint value of the second pressure regulator, the following energies can be used: this energy is contained in the pressure fluid flowing back in the return line in order to, in particular, unload the drive (antitieb) of the second pump. Thereby saving energy.

It can be provided that a check valve is connected between the return line and the tank, which check valve only allows a fluid flow (Fluidstrom) from the tank to the return line. This makes it possible to avoid cavitation in the return line (kavision).

It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respectively stated combination but also in other combinations or alone without leaving the scope of the present invention.

Drawings

The invention is explained in detail below with the aid of the figures. The figures show:

fig. 1 is a connection diagram of an actuator-side part of a hydraulic drive system according to the invention;

fig. 2 is a connection diagram of a pump-side part of a hydraulic drive system according to a first embodiment of the invention;

fig. 3 is a connection diagram of a pump-side part of a hydraulic drive system according to a second embodiment of the invention; and

fig. 4 is a connection diagram of a pump-side part of a hydraulic drive system according to a third embodiment of the invention.

List of reference numerals:

10 Hydraulic drive system (first embodiment)

10' Hydraulic drive System (second embodiment)

10 '' Hydraulic drive system (third embodiment)

11 actuator

12 pot

13 third pressure sensor

20 control device

21 first pump

22 second pump

30 return line

31 first inlet line

32 second input line

33 first pressure sensor

34 second pressure sensor

40 drive device (first embodiment)

40' drive (second embodiment)

41 first electric motor

42 second electric motor

43 first speed adjusting device

44 second rotational speed adjustment device

45 power supply network

46 cell

50 distribution transmission mechanism

51 first output shaft

52 second output shaft

53 input shaft

60 valve assembly

61 first direction valve

62 second direction valve

63 third directional valve

70 first pressure regulator

71 first adjusting plate

72 position sensor

73 rating-regulating device

80 second pressure regulator

81 second regulating plate

83 check valve.

Detailed Description

Fig. 1 shows a hydraulic drive system 10 according to the invention; 10'; 10 '' of the actuator side. The hydraulic drive system 10; 10'; this part of 10 ″ is identically formed in all three embodiments of the invention. The hydraulic drive system 10; 10'; 10 "comprises a first and a second inlet line 31; 32 and a return line 30. The mentioned lines 30; 31; for example, 32 can be designed as a passage in a valve body (Ventilblock) which passes through the valve body over the entire length of the valve body. The mentioned lines 30; 31; 32 are closed in a fluid-tight manner at the end to the right in fig. 1, wherein the lines are connected at the opposite end to the hydraulic drive system 10; 10'; 10 ″ on the pump side shown in fig. 2 to 4.

The hydraulic drive system 10; 10'; 10 ″ currently comprises two actuators 11, wherein the number of actuators 11 can be selected largely arbitrarily. The actuator 11 is, for example, a hydraulic cylinder and/or a hydraulic motor. The actuator 11 is connected to the first and second supply lines 31 via associated valve assemblies 60; 32 and the return line 30. With the valve assembly 60, on the one hand, the direction of movement and the speed of movement of the associated actuator 11 can be adjusted, wherein for this purpose a first directional valve 60 is provided. The first directional valve is constructed in the form of a continuously adjustable 4/3-directional valve, the 4/3 directional valve being electromagnetically adjustable, wherein it is connected to the control device 20. Furthermore, it can be adjusted which supply lines 31; 32 to supply pressure fluid to said actuator 11. For this purpose, a second directional valve 62 is provided, which is connected to the supply line 31; 32 and the first direction valve 61. The second directional valve 62 is designed as an 2/3 directional valve, which 2/3 directional valve can be adjusted electromagnetically, wherein it is connected to the control device 20. In one switching position, the first supply line 31 is connected to the first directional valve 61, and in the other switching position, the second supply line 32 is connected to the first directional valve 61. Furthermore, it can be regulated to which lines 30 the pressure fluid from the actuator 11 should flow back; 31; 32 (c). For this purpose, a third directional valve 63 is provided, which is connected between the return line 30 or the first supply line 31 and the first directional valve 61. The third directional valve 63 is designed as an 2/3 directional valve, which 2/3 directional valve can be adjusted electromagnetically, wherein it is connected to the control device 20. In one switching position, the return line 30 is connected to the first directional valve 61, and in the other switching position, the first supply line 31 is connected to the first directional valve 61.

It is additionally conceivable that the pressure fluid returned by the actuator 11 can be conducted into the second supply line 32. It is further noted that further connection variants of the valve assembly 60 exist, which have the same function as the previously explained valve assembly 60. For example, it is possible for each line 30; 31; two 2/2 directional valves which can be adjusted continuously are respectively associated with each of the valves 32, and each of the 2/2 directional valves is connected to the associated connection of the associated actuator 11.

It is also to be noted that the third pressure sensor 13 is connected to the two connections of the actuator 11, in each case one pressure sensor 13, which is in turn connected to the control device 20. On the one hand, the pressure sensor 13 can measure a load pressure against which the actuator 11 is operated. Corresponding to DE 10340993 a1, the delivery pressure of the pump can be adjusted as a function of the load pressure. The return pressure (Druck um rucklauf) is important in particular in the case in which a pulling load acts on the actuator 11, so that the energy contained in the returned pressure fluid can be used elsewhere again. On the basis of the respective return pressure, it can be determined, for example, in which position the third directional valve 63 should be connected for optimum energy utilization.

Note also that, in the line 30; 31; the pressure in 32 is preferably different. The return line 30 has the lowest pressure in this case, the pressure in the first supply line 31 being the highest. The second inlet line 32 has a pressure between the aforementioned extremes.

Fig. 2 shows a connection diagram of a pump-side part of a hydraulic drive system 10 according to a first embodiment of the invention. The hydraulic drive system 10 has a first and a second pump 21; the first and second pumps currently each have a constant displacement volume, 22, wherein they are designed, for example, as external gear pumps. The first and second pumps 21; 22 typically supply pressure fluid to the associated first or second supply line 31; 32 (c). However, for example, an operating state can be achieved in which pressurized fluid flows from the first supply line 31 through the first pump 21 into the second supply line 32, which is at a lower pressure, so that the first pump 21 is operated in a motor-driven manner. A similar situation applies to the second pump 22.

The first and second pumps 21; 22 are connected in series between the first inlet line 31 and the return line 30. The second input line 32 is connected to the first and second pumps 21; 22 such that the pressure there is between the pressure of the first inlet line 31 and the pressure in the return line 30. The first pump 21 is in rotational driving connection with a first output shaft 51, wherein the second pump 22 is in rotational driving connection with a second output shaft 52.

The drive means 40 comprise a mechanical distribution transmission 50, which corresponds to the inlet line 31; 32 have two rotational degrees of freedom, wherein it is designed, for example, as a planetary gear. The distribution transmission 50 is provided with, in addition to the already mentioned output shaft 51; 52 has an input shaft 53. The input shaft 53 is in rotational driving connection with the first electric motor 41. In operation, a torque balance occurs on the distributor gear 50, which results in: on the input shaft 53 and on the first and second output shafts 51; the torques at 52 are in a fixed ratio to each other, which ratio depends on the transmission ratio in the distribution transmission 50. Whereby the first and second pumps 21; 22, so that the pressure drop across the first and second inlet lines 31; 32 and the return line 30 to produce a desired pressure classification (druckabstufang).

Note that the input shaft 53 and the first and second output shafts 51; the speed of rotation of 52 is not in a fixed ratio. If the first pump 21 is operated as mentioned above in a motor-driven manner, the direction of rotation of the first output shaft 51 is reversed relative to the direction of rotation in the adjusting mode (regelbettieb), so that energy is transmitted from the first output shaft 51 via the distribution gear 50 to the second output shaft 52 and/or to the input shaft 53.

The first electric motor 41 is electrically connected to a first speed adjustment device 43. The first speed control device 43 can be, for example, a frequency converter, by means of which the speed of the input shaft 53 can be controlled. The first rotational speed control device 43 is connected to a supply network 45, which is preferably designed as a dc network. The power supply network 45 can be connected to a public power grid, for example, by means of a rectifier. The power supply network 45 is connected to a rechargeable battery. In the above-mentioned motor-mode operation of the first pump 21, it may occur that: the feedback energy is not fully received by the second pump 22. In this case, the direction of rotation of the input shaft 53 is also reversed with respect to the regulating operation, so that the first electric motor 41 is operated in generator mode, wherein it feeds back electrical energy into the supply grid 45. This energy is preferably used to charge the battery 46.

Furthermore, the first pressure sensor 33 is to be noted, with which the pressure in the first supply line 31 can be measured. The first pressure sensor 33 is connected to the already mentioned control device 20, which in turn is connected to the first rotational speed adjustment device 43. The control device 20 is set up in the type of a pressure regulator. It obtains the highest load pressure from the measurement of the third pressure sensor (reference numeral 13 in fig. 1). The load pressure is increased by a predetermined differential pressure for obtaining a pressure setpoint value. The control device 20 regulates the rotational speed of the first electric motor 14 in such a way that the actual pressure measured by the first pressure sensor 31 is equal to the pressure setpoint value. The control device 20 preferably operates as a continuous linear regulator, in particular as a P-regulator or as a PD-regulator. The respective regulator is calculated by the control device 20, preferably in a time-discrete manner (zeitdistret). The control device 20 preferably comprises a programmable digital computer. The pressure in the second supply line 32 results from the transmission ratio of the distribution transmission 50 and the pressure in the first supply line 31 and the return line 30.

Also noted are the second pressure regulator 80 and the check valve 83. The pressure in the return line 30 should be increased to a defined value relative to the ambient pressure by means of the second pressure regulator 80. The pressure setpoint value of the second pressure regulator 80 can be regulated electrically, wherein the second pressure regulator 80 is connected to the control device 20 for predetermining the pressure setpoint value. The second pressure regulator 80 has a continuously adjustable second regulator plate 81 connected between the return line 30 and the tank 12. By means of the second regulating plate 81, it is possible to intercept pressure fluid flowing from the return line 30 to the tank 12, so that the pressure in the return line 30 rises. The check valve 83 is connected between the tank 12 and the return line 30, wherein it only allows fluid flow from the tank 12 to the return line 30. Voids in the return line 30 should therefore be avoided.

If the control device 20 detects a load pulling on one of the actuators 11 by means of the measured values of the third pressure sensor (reference number 13 in fig. 1), the pressure setpoint of the second pressure regulator 80 can be increased, so that the pressure in the return line 30 rises. Thereby reducing the driving power required to drive the first pump 21. Within the scope of the invention, the mentioned pressure setpoint value can also be increased such that it is higher than the pressure in the second supply line 31. The second pump 22 is then operated in a motor-driven manner, wherein the corresponding energy is conducted via the distribution gear 50 to the first pump 21 and/or to the first electric motor 41.

Fig. 3 shows a connection diagram of a pump-side part of a hydraulic drive system 10' according to a second embodiment of the invention. The second embodiment is constructed identically to the first embodiment, apart from the differences described below, reference being made in this connection to the explanations with regard to fig. 1 and 2. In fig. 1 to 3, identical or corresponding parts are provided with the same reference numerals.

In the second embodiment, the second pressure regulator and the non-return valve (80; 83 in fig. 2) are dispensed with, the return line 30 being connected directly to the tank 12. In contrast, the pressure in the return line 30 is substantially equal to the pressure in the tank 12.

Furthermore, the electronic regulation of the pressure in the first supply line 31 is replaced by a hydraulic pressure regulation. This makes it possible to regulate the pressure in the first supply line 31 more quickly. A first pressure regulator 70 is provided having a continuously adjustable first regulation plate 71. The first supply line 31 is connected to the tank 12 via the first control plate 71. In the opening direction, the first control plate 71 or the corresponding valve (ventilschiber) is acted upon by the pressure in the first supply line 31, wherein the valve is acted upon in the opposite direction by a spring, the prestress of which can be adjusted electromagnetically. The respective electromagnet is connected to the control device 20.

The adjustment of the first adjustment plate 71 can be measured by means of a position sensor 72 connected to the control device 20. The following operating states can be detected by means of the position sensor 72, for example: in the operating state, the first adjustment plate 71 is largely opened. These operating states are accompanied by higher energy losses. In order to avoid said energy losses, the control device 20 reduces the rotational speed of the first pump 21 by means of the first rotational speed control device 43. This leads to the following results: the first regulation plate 71 is closed, so that the energy loss is reduced. If the position sensor 72 indicates that the first adjustment plate 71 is completely closed, the rotational speed of the first electric motor 41 is increased by the control device 20 to such an extent that the first adjustment plate 71 is minimally opened.

Fig. 4 shows a connection diagram of a pump-side part of a hydraulic drive system 10 ″ according to a third embodiment of the invention. The third embodiment 10 ″ is constructed identically to the first embodiment, apart from the differences described below, reference being made in this connection to the embodiment in relation to fig. 1 and 2. Identical or corresponding parts in fig. 1, 2 and 4 are provided with the same reference numerals.

In the second embodiment, the second pressure regulator and the non-return valve (80; 82 in fig. 2) are dispensed with, the return line 30 being connected directly to the tank 12. In contrast, the pressure in the return line 30 is substantially equal to the pressure in the tank 12.

Instead of the distribution gear (reference number 50 in fig. 2) a first and a separate second electric motor 41 are provided; 42. the first and second output shafts 51; 52 are driven by the associated electric motors 41; 42 motor shaft. The first and second electric motors 41; 42 are each electrically connected to an associated first or second speed control device 43; 43. The first and second rotational speed control devices 43, which are designed, for example, as frequency converters; 44 are connected to a common power supply network 45. The power supply system 45 is designed, for example, as a dc power supply system, wherein it is connected to a rechargeable battery 46.

As in the first exemplary embodiment, the first supply line 31 is connected to a first pressure sensor 33, which is used in the framework of electronic pressure regulation and during which the rotational speed of the first electric motor 41 is regulated for setting the pressure in the first supply line 31 to a predefined first pressure setpoint value.

In a similar manner, the second supply line 32 is connected to an associated second pressure sensor 34, which is in turn connected to the control device 20. Within the scope of the pressure regulation, the rotational speed of the second electric motor 42 is regulated by means of the second rotational speed regulation device 44 for setting the pressure in the second supply line 32 to a predefined second pressure setpoint value. Whereby the first and second inlet lines 31 can be adjusted independently of each other; 32.

Once the pump 21; 22 is switched to motor mode operation within the pressure-regulated range, by the associated electric motor 41; 42 feed back electrical energy into the supply network 45. This electrical energy can be used to drive the respective other electric motor 42; 41 or for charging the battery 46. It should be understood that the energy stored in the battery 46 can be used to drive the electric motor 41; 42.

Claims

1. a hydraulic drive system having a first and at least one second supply line (31; 32) and a return line (30), wherein at least one actuator (11) is provided, which can be connected in a fluid-exchange manner, via an associated valve assembly (60), optionally to at least one of the supply lines (31; 32) and/or to the return line (30), wherein the first supply line (31) is connected to a first pump (21), wherein each second supply line (32) is connected to an associated second pump (22), wherein the return line (30) is connected to a tank (12),

characterized in that a drive device (40; 40 ') is provided, which has a plurality of output shafts (51; 52) which are each in rotary drive connection with an associated first or second pump (21; 22), wherein the drive device (40; 40 ') is designed such that energy can be exchanged between the output shafts (51; 52) by means of the drive device (40; 40 '),

the actuator (11) is connected to the first and second supply lines (31; 32) and the return line (30) by means of an associated first directional valve (61) and a second directional valve (62),

wherein a first directional valve (61) can regulate the direction and speed of movement of the associated actuator (11), and a second directional valve (62) can regulate which inlet lines (31; 32) can supply pressure fluid to the actuator (11), which second directional valve is connected between the inlet lines (31; 32) and the first directional valve (61),

wherein the first and second pumps (21; 22) are connected in series between the first inlet line (31) and the return line (30), and the second inlet line (32) is connected between the first and second pumps (21; 22) such that the pressure there is between the pressure of the first inlet line (31) and the pressure in the return line (30).

2. The hydraulic drive system of claim 1,

wherein the drive device (40; 40') comprises at least one electric motor (41; 42) which is connected to an associated rotational speed adjustment device (43; 44) in each case in such a way that the rotational speed of the electric motor can be adjusted.

3. The hydraulic drive system of claim 2,

wherein the output shaft (51; 52) is a component of a mechanical distribution gear (50), wherein the distribution gear (50) has as many rotational degrees of freedom as there are output shafts (51; 52).

4. The hydraulic drive system of claim 3,

wherein the distribution gear (50) has a single input shaft (53) which is in rotary drive connection with the associated first electric motor (41).

5. The hydraulic drive system of claim 2,

wherein the output shafts (51; 52) are each in rotary drive connection with an associated electric motor (41; 42), wherein the electric motors (41; 42) are connected to a common power supply network (45), wherein energy can be exchanged between the electric motors (41; 42) at least indirectly via the power supply network (45).

6. The hydraulic drive system of claim 1,

wherein the first and at least one second pump (21; 22) are connected in series between the first feed line (31) and the return line (30), wherein the at least one second feed line (32) is connected between the two pumps (21; 22) in each case.

7. The hydraulic drive system of claim 6,

wherein the first pump (21) has a constant or adjustable displacement volume, wherein the at least one second pump (22) has a constant displacement volume.

8. The hydraulic drive system of any one of claims 2 to 7,

wherein the first supply line (31) is connected to a first pressure sensor (33), wherein the first pressure sensor (33) and the at least one rotational speed regulation device (43; 44) are connected to a control device (20), wherein the control device (20) is designed in such a way that the pressure in the first supply line (31) that can be measured by means of the first pressure sensor (33) can be set to a predefined or predefinable setpoint value by regulating the rotational speed of the at least one electric motor (41; 42).

9. The hydraulic drive system of claim 1,

a first pressure regulator (70) having a first regulating plate (71) that can be regulated is provided, wherein the first supply line (31) is connected to the tank (12) via the first regulating plate (71), wherein the first pressure regulator (70) is designed in such a way that the pressure in the first supply line (31) can be regulated by regulating the first regulating plate (71) to a predefined or predefinable setpoint value.

10. The hydraulic drive system of claim 1,

wherein a second pressure regulator (80) having a second regulating plate (81) that can be regulated is provided, wherein the return line (30) is connected to the tank (12) via the second regulating plate (81), wherein the second pressure regulator (80) is designed in such a way that the pressure in the return line (30) can be set to a predefined or predefinable setpoint value by regulating the second regulating plate (81).

11. The hydraulic drive system of claim 10,

wherein a non-return valve (83) is connected between the return line (30) and the tank (12), which non-return valve only allows a fluid flow from the tank (12) to the return line (30).