JPH05202842A - Hydraulic machine equipped with waste oil discharger - Google Patents

Abstract

PURPOSE: To reduce an excess pressure in a drain oil chamber so as to avoid splashing loss by disposing a pump device between a drain oil port and a tank for sucking drain oil from the drain oil chamber of a motor. CONSTITUTION: A fluid flow from a hydraulic pump 1 is supplied to a nozzle 35 of a jet pump 34 through connection line 41 having a working pressure line 3 or 4 and a throttle element 42, a shuttle valve 40 and a working medium line 39. When the flow is discharged from the nozzle 35 at a high speed, a negative pressure is generated at an inlet portion of the jet pump. When this negative pressure reaches a value sufficiently overcoming a flow drag in a channel between a hydraulic motor 25 and a tank 9, drain oil is sucked from a drain oil chamber of the hydraulic motor 25 through a drain oil port 30. Kinetic energy of the sucked drain oil is converted into pressure energy for transferring the drain oil to the tank 9 through a drain oil line 38. Consequently, due to the suction of the jet pump 34, a liquid level in the drain oil chamber becomes lower than a level of a rotation driving mechanism, thus avoiding loss caused by splashing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic machine having a drive mechanism incorporated therein and a housing including an oil discharge chamber for collecting the oil discharge and connecting to the tank via an oil discharge port, particularly an axial piston. Machine related.

[0002]

2. Description of the Related Art A hydraulic device of this kind in which the oil discharge chamber is constantly filled with oil discharge due to internal leakage occurring during operation is disclosed in German Laid-Open Patent Publication No. 29 31 641 and German Patent Publication No. 3638 890. This drained oil is discharged to the tank via an oil drain line connected to the oil drain port.

[0003]

Due to the resistance in the oil drain line, the oil drainage in the oil drainage chamber is under excessive pressure, and the drive parts rotating in the oil drainage chamber have a correspondingly large splash loss. (Loss caused by stirring the drain oil).

It is an object of the present invention to provide a hydraulic machine of the type mentioned above, in which splashing losses can be prevented.

[0005]

This object is achieved by providing a pump device between the drain port and the tank for sucking drain oil from the drain chamber.

A pump device for sucking up the drain oil is indeed known from DE-OS 29 09 878, which pump device is connected to the seal part of the bearing of the hydraulic load cylinder and the seal part It discharges the flow of waste oil in the form of passing oil, prevents the oil from escaping to the surroundings, and seals the bearing sufficiently.

The pump device according to the invention is designed so that the oil drainage is either completely sucked up from the oil drainage chamber or, preferably, at a lower level than the rotary drive mechanism components which cause splash losses. It can be designed to generate (volume flow).

Furthermore, the pump device can also be designed to produce a constant or variable flow rate. A pumping device with a constant flow rate is particularly suitable for completely sucking up drain oil from the drain chamber. However, by using the valve device, the operation of the pump device can be switched on and off at appropriate intervals so that a specific oil drainage level can be maintained within a predetermined fluctuation range. This valve device is used, for example, when the splashing loss in the oil discharge chamber of the hydraulic machine exceeds a non-negligible value, for example, the instantaneous rotation speed or the instantaneous operating pressure of the hydraulic machine or the pressure generated or consumed by the hydraulic machine. It can also be used when turning on and off the operation of a pump device having a constant flow rate or a variable flow rate based on a parameter such as the flow rate that is set.

Another feature of the present invention is that the flow rate is made variable through the control of the pump in order to adjust the flow rate based on one of the above-mentioned parameters as a control parameter.

The control using the flow rate as a control parameter is preferably realized by a pump device including a jet pump whose working medium connection port is connectable to a working medium source that generates a flow rate corresponding to the flow rate of the hydraulic machine. According to the first mode, this working medium connection port is connected to the working pressure line connected to the hydraulic machine, and according to the second mode, it is connected to the auxiliary pump connected to the hydraulic machine.

For example, in a hydraulic machine in which the bearing for the drive mechanism is not sufficiently supplied with lubricating oil because the bearing is located below the drain oil level, in order to supply the lubricating oil to the bearing through the passage system. A flushing oil connection leading to the bearing and connected to another valve device with two switching positions that can switch the supply of the flushing oil to the hydraulic machine on and off, for example, based on one of the above parameters. A flushing oil connection is advantageous.

Advantageously, these valve devices are functionally associated with a two-way valve arranged between the working medium source for the jet pump and the flushing oil connection of the hydraulic machine. By doing so, for example, when the splash loss in the oil discharge chamber reaches a level that cannot be ignored, the intake of the exhaust oil and the supply of flushing oil to the hydraulic machine are simultaneously turned on or turned off. can do.

According to a second aspect, the pumping device comprises a positive displacement pump. In order to switch on and off, this positive displacement pump can be connected to the first-mentioned valve device, which is formed as a three-way valve arranged in the drain line connecting the drain of the hydraulic machine to the tank. .. The three-way valve connects the drain line to the suction port of the positive displacement pump at one switching position and to the tank at the other switching position.

According to yet another feature of the invention, the pump system is constructed and controlled as a constant displacement pump based on one of the control parameters, namely the rotational speed, operating pressure or flow rate of the hydraulic machine. A throttle control valve for controlling the flow rate generated by the positive displacement pump driven at high speed is included. Similarly, a separate throttling element may be provided in connection with the flushing connection of the hydraulic machine for controlling the supply of flushing oil to the hydraulic machine according to one of the above control parameters.

It is advantageous to provide the hydraulic machine with a ventilation device in order to prevent negative pressure in the oil drainage chamber.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The illustrated hydraulic machine is an axial piston type driven by a diesel engine (not shown).
A variable displacement hydraulic pump 1 having two discharge directions;
A constant displacement axial piston type hydraulic motor corresponding to a bidirectional flow, and an auxiliary pump 2 mechanically connected to the hydraulic pump 1 and having one discharge direction and a constant displacement type
And an oil drainage device according to the invention.

The hydraulic pump 1 and the hydraulic motor are connected to each other in a closed circuit via two operating pressure lines 3 and 4. A line 5 with two check valves 6 connects the two operating pressure lines 3, 4. The auxiliary pump 2 is connected to the tank 9 via the line 7 and the filter 8.
This pump serves as a replenishment pump, and is connected to the feed line 1 connected between the above two check valves 6.
It is connected to line 5 via 0. These two check valves 6 prevent the flow in the direction towards this connection point.
A pressure limiting valve 11 that reliably limits the maximum supply pressure and guides the tank 9 through a relief line 12 is connected to the feed line 10. The oil discharge port of the hydraulic pump 1 is connected to the relief line 12 via a line 13.

The hydraulic motor is shown in FIGS. 7 and 8 in two different shapes, and each has a built-in cylindrical housing 14 in which a drive mechanism rotated by a bearing 15 is mounted.

Reference numeral 16 in FIG. 7 denotes a conventional swash plate type motor, the swash plate 17 of which is attached to the housing 14 so as not to rotate near one wall. Further, the drive mechanism of the swash plate type motor includes a swash plate 17 and a drive shaft 18 rotatably mounted by a bearing 15 in the housing side wall on the opposite side, and a piston 21 capable of reciprocating in a hole 20 in the same axial direction. It has a cylinder block 19 non-rotatably (relatively) attached to a drive shaft having a and a slipper 22 for supporting a piston 21 on a swash plate 17. The bearing 15 is
Through the passage 23, the housing 1 is provided for the purpose of supplying lubricating oil.
4 is connected to the flushing oil connection port 24 in the cylinder wall.

The hydraulic motor indicated by the reference numeral 25 in FIG. 8 is a conventional oblique shaft type motor, and its drive mechanism is different from that shown in FIG. 7 mainly in the following points. That is, the drive shaft 1 rotatably mounted via the cylinder block 19 having the piston 21 and the bearing 15 on the cylindrical wall of the housing.
In addition to 8, the swash plate 17 is formed as a drive shaft flange and is provided with a piston 21, and further faces a cylinder block 19 to which a central journal 26 is (relatively) non-rotatably mounted, and the piston 21 does not have a slipper inserted. It is different in that it is directly supported by. Control plate 27
The passage 23, which is guided to the control surface of the cylinder block 19 which extends through the central journal 26, extends through the central journal 26 and supplies pressure oil to the individual bearings 15 via tributaries from the internal oil circuit of the hydraulic motor for lubrication. ..

A part of the housing which is not occupied by the drive mechanism serves as an oil drain chamber 29 for storing the oil drain generated during the operation of each hydraulic motor 16 or 25. The oil drainage chamber 29 is provided with an oil drainage port 30 and an oil drain line 31 that follows it.
Is connected to the tank 9 via. Both hydraulic motors 1
6 and 25 are configured to be mounted horizontally, and the oil drain port 30 is formed at the lowest position of the housing cylindrical wall. The housing 14 is provided with a connecting line for ventilation (schematically shown in FIGS. 1 to 6) at the highest position in the installed state, which leads to a ventilation valve 33 which can be operated in a manner not shown via a ventilation line 32. There is.

The hydraulic drive system shown in FIG. 1 includes a hydraulic motor 25 shown in FIG.
Included is a jet pump 34 of conventional design having a housing having a nozzle 35 and a diffuser 36 facing the nozzle therein. This housing has a nozzle 35
Has a working medium port aligned with respect to, a pressure medium connection port aligned with the diffuser 36, and a suction connection port connected between the nozzle 35 and the diffuser 36.
The suction connection port is used as the first line portion 37 of the oil drain line 31.
It is connected to the oil discharge port 30 of the hydraulic motor 25 via. The second line portion 38 of the oil drain line 31 connects the pressure port of the jet pump 34 to the tank 9. The working medium line 39 connects from the working medium port of the jet pump 34 to the shuttle valve 40 of the connecting line 41 connecting the working pressure lines 3 and 4 to each other. Each throttle element 42 is a shuttle valve 40.
Are arranged on both sides of.

The operation of the hydraulic drive shown in these figures is well known to those skilled in the art and need not be described, only the operation of the pump device of the present invention formed as a jet pump 34 will be described. .. It is the hydraulic pump 1 that produces a flow rate equal to the flow rate handled (or consumed) by the hydraulic motor 25 that acts as a working medium source for the jet pump 34. This flow rate depends on the working pressure line 3 or 4, the relevant part of the connecting line 41 with the throttling element 42, the shuttle valve 40, the working medium line 39.
It is supplied to the nozzle 35 of the jet pump 34 via the working medium port of the jet pump 34. When this flow rate is discharged from the nozzle 35 at a high speed, a negative pressure is generated at the suction port of the jet pump, and this negative pressure is sufficient to overcome the flow resistance of the pipeline between the hydraulic motor 25 and the tank 9. When the value is reached,
Exhaust oil is sucked from the oil discharge chamber 29 of the hydraulic motor 25 through the oil discharge port 30 and the first line portion 37 of the oil discharge line 31.
In the diffuser 36, the kinetic energy of the sucked oil is changed to the pressure connection port and the second line portion 3 of the oil drain line 31.
The waste oil is converted into pressure energy to be conveyed to the tank 9 via 8. Therefore, as for the suction capability of the jet pump 34, the level of the drainage oil is from the drainage chamber 29 to the rotary drive mechanism component 1.
To be lower than the levels of 7, 18, 19, 21
That is, in this embodiment, it is designed to be completely sucked out. In this way, it is possible to avoid the loss due to the splashing generated by the drive mechanism components 17, 18, 19, 21 that would normally rotate during oil drainage. This applies to the entire range of the flow rate discharged by the hydraulic pump 1 and consumed by the hydraulic motor 25. The reason is that this flow rate, the flow rate generated by the jet pump 34, and the amount of drained oil that is generated (sucked out) by the hydraulic motor 25 per unit time match. A part of the drained oil is used for lubrication from the internal hydraulic circuit via the pipe line 23 and its branch pipe independently of the suction (discharge) stroke for the bearing 1.
The pressure oil is supplied to No. 5 and then flows into the oil discharge chamber 29. Further, the jet pump 34 is designed so that this suction stroke is started at the time when the flow rate discharged by the hydraulic pump 1 and consumed by the hydraulic motor starts a splash loss that cannot be ignored in the hydraulic motor. It

The hydraulic drive system shown in FIG. 2 has the same structure and function as that shown in FIG.
Instead of using the hydraulic motor 16 shown in FIG. 7, a two-position two-way switching valve 43 equipped with a throttle 45 is provided on the supply line 1.
0 is provided in the flushing oil line 44 connected to the flushing oil connection port 24 of the hydraulic motor 16, which is different from that in FIG. The switching valve 43 is held by a spring 46 in an inoperative position where the two connecting directions shown in FIG. 2 are blocked. It is electromagnetically moved to an operating position where the two connecting directions are connected to each other. The operation of the electromagnet is performed via a signal line 47 by an electric signal generated by a speed sensor 48 provided on the drive shaft of the hydraulic motor 16.
The speed sensor is set so that the switching valve 43 is put into the operating position before the critical speed of the hydraulic motor 16 at which the supply of the lubricating oil to the bearing 15 becomes insufficient, and the speed sensor is operated. The pressure oil is branched and supplied to the bearing 15, and sufficient lubricating oil is supplied.

The hydraulic drive system shown in FIG. 3 differs from that shown in FIG. 2 only in the following points. That is, the hydraulic motor 1
The two-position two-connection directional control valve 43 is also used for turning on and off the jet pump 34, in addition to the role of turning on and off the supply of the flushing oil to the pump 6, and the auxiliary pump 2 is the working medium source of the jet pump 34. Differ in that it is used as. For this purpose, the working medium line 39 comprises a two-position two-connection directional control valve 43 and a throttle 45.
Is connected between and. The speed sensor 48 is set according to the same standard as that of the embodiment shown in FIG. That is, it is performed based on the critical speed of the supply of the lubricating oil to the bearing 15. If at this critical speed splash losses occur in the hydraulic pump 16 which can no longer be neglected, the jet valve 34 can be used to prevent this splash loss, apart from the flushing oil supply by means of the switching valve itself. You can switch to "on" to get the required low speed.

The hydraulic drive system shown in FIG. 4 has the same structure as that of FIG. 1, but there are the following differences regarding the arrangement of the pumps. This pump arrangement includes a volumetric discharge pump 50 driven at a constant speed by a drive motor 49, such as an axial piston configuration having unidirectional volumetric discharge and metered volumetric discharge. Therefore, the working medium line 3 shown in FIG.
9 and the connecting line 41 including the shuttle valve 40 and the throttling element 42 are omitted and a two-position three-way switching valve 51 is provided between the positive displacement pump 50 and the hydraulic motor 25. The first connection port of the switching valve 51 is guided to the oil discharge port 30 of the hydraulic motor 25 via the first line portion 37 of the oil discharge line 31. The second connection port is connected to the suction port of the positive displacement pump 50 whose pressure connection port is guided to the tank 9 via the second line portion 38 of the oil drain line 31 via the line portion 52. A bypass line 53 that bypasses the volumetric discharge pump 50 connects the third connection port of the two-position three-way switching valve 51 to the second line portion 38 of the oil drain line 31. The two-position three-way switching valve 51 is held in the inactive position shown in FIG. 4 by the spring 54, in which the connection to the positive displacement pump 50 is blocked and the remaining two connection ports are connected to each other. .. The switching valve is electromagnetically moved to an operating position where the connection to the bypass line 53 is blocked and the remaining two connection ports are connected to each other. The control of the electromagnet is performed by the signal line 55 connected to the speed sensor 48 arranged on the drive shaft of the hydraulic motor 25 in the same manner as described with reference to FIG.
Done through.

The operation of the pump device of the present invention configured as a positive displacement pump is as follows. The speed sensor 48 is set to the speed of the hydraulic pump at which the splashing losses due to the drive mechanism parts 17, 18, 19, 21 rotating in the leaking oil are no longer negligible. Below this set speed, the two-position three-way switching valve 51 is in the inoperative position, and the oil discharge chamber 29 of the hydraulic motor 25 is in the bypass line 53.
Is unloaded into the tank 9 via the. When the hydraulic motor 25 driven by the hydraulic pump 1 reaches the set speed, the speed sensor 48 supplies an electric signal, the two-position three-way switching valve 51 switches to the operating position, and the driving motor 49
The volumetric discharge pump 50 driven at a constant speed sucks up the waste oil from the waste oil chamber 29. The discharge capacity of the volumetric discharge pump 50 is such that, even when the drive motor 25 is at maximum rotation, the liquid level of the drainage oil in the drainage chamber 29 is the rotation mechanism parts 17, 18, 19,
21 below the level, and therefore splashing losses can be prevented over the entire operating range of the hydraulic motor 25. Lubricating oil is reliably supplied to the bearing 15 by the same method as the hydraulic motor 25 used for hydraulic drive shown in FIG. 1, that is, by supplying pressure oil from the internal hydraulic circuit to the bearing 15. After being lubricated, this pressure oil flows into the oil discharge chamber 29 and is sucked up as a part of the oil discharge.

The hydraulic drive system shown in FIG. 5 has the same structure as that shown in FIG. 4, but differs in the following points. That is, instead of the hydraulic motor 25, the speed sensor 48 is provided via the hydraulic motor 16 and a signal line as shown in FIG.
The two-position two-way switching valve 43 connected to the above is used, and the two-position three-way switching valve in the oil drain line 31 is formed as a throttle control valve 56 with an intermediate position. The speed sensor 48 is set to the critical speed at which the supply of the lubricating oil to the bearing 15 of the hydraulic motor 16 begins to become insufficient as already described with reference to FIG. When this critical speed is reached, the two-position two-way switching valve 43 is switched to the operating position, and the hydraulic motor 1 for supplying the lubricating oil to the bearing 15 is supplied.
The supply of flushing oil to 6 is started. At the same time, the throttle control valve 56 starts to open so that the positive displacement pump 50 sucks the oil flow proportional to the cross section of the control valve from the oil discharge chamber 29 of the hydraulic motor 16. As the speed of the hydraulic motor 16 increases, the opening area of the control valve 56 increases, thus increasing the flow of pumped drain oil. The design of the throttle control valve 56 is such that the level of the oil drainage in the oil drainage chamber 29 over the entire speed range of the hydraulic motor 16 is the rotation mechanism parts 17, 1.
It is done so as to be maintained at a substantially uniform level below 8, 19, 21. When a non-negligible splash loss has already occurred at the critical speed of the hydraulic motor 16 set in the speed sensor 48, the throttle control valve 56 prevents this splash loss by the second speed sensor. It is possible to control to a low speed.

The hydraulic drive system shown in FIG. 6 has the same structure as that shown in FIG. 5, but differs in the following points. That is, the two-position two-way switching valve of the flushing oil line 44 is formed as the throttle control valve 57, and the operating pressure of the hydraulic drive system is used as a control parameter of this throttle control valve 57 and the oil discharge line 31. The difference is that a control valve 56 is provided. For this purpose, both control valves 5
6, 57 proportional electromagnets are connected via a signal line 58 to a pressure / voltage converter 59, for example in the form of a potentiometer, which converter 59 is known in FIG. 2 via a hydraulic connection line 60. The connecting line 41 is connected to the shuttle valve 40 without throttling elements. In this way, the oil drainage chamber 2
Suction of exhaust oil from 9 and supply of flushing oil to the hydraulic motor 16 are controlled in proportion to the pressure of the working pressure line 3 or 4, and supply of lubricating oil to the bearing 15 is performed at the full speed of the hydraulic motor 16. It is done reliably over a range and the level of drainage is maintained below the rotating mechanism parts 18, 19, 21, 22.

It is of course possible to use a variable displacement type motor instead of the fixed type hydraulic motors 16 and 25. The volumetric discharge pump 50 enables direct control of the flow rate of drain oil without the control valve 56 by adjusting the speed or the discharge capacity.
A variable displacement pump that operates at a constant speed or a variable speed may be used. It is also possible to use a flow rate / voltage converter instead of the pressure / voltage converter 54. Two-way valve 43, 57
Alternatively, one or both of the three-way valves 51 and 56 are
It is also possible to design or control the drain suction, if necessary, and, if necessary, to switch the flushing oil supply on and off independently of the control parameters. The connection destination of the hydraulic pump 1 may be the pump device of the hydraulic motor or another pump device that sucks up the waste oil.

[0031]

As described above, according to the present invention, a hydraulic machine having a drive mechanism and an oil drain chamber connected to a tank inside a housing is provided with a pump device for sucking the oil drain from the oil drain chamber. Since it is provided between the oil discharge port and the tank, there is an effect that the oil discharge level in the housing can be lowered and the splashing loss due to the drive parts rotating in the oil discharge chamber can be prevented.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a hydraulic drive system with an oil drainage device according to a first embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram in which flushing oil supply is added to the hydraulic drive system with the oil discharge device shown in FIG.

FIG. 3 is a hydraulic circuit diagram shown in FIG. 2 having a modification of the oil drainage device.

FIG. 4 is a hydraulic circuit diagram of a hydraulic drive system with an oil drainage device according to a second embodiment of the present invention.

5 is a hydraulic circuit diagram in which a modified example of the oil discharge device and a flushing oil supply of a hydraulic motor are added to the hydraulic drive system shown in FIG.

FIG. 6 is a hydraulic circuit diagram in which a modified example of the oil discharge device and a flushing oil supply of a hydraulic motor are added to the hydraulic drive system shown in FIG.

FIG. 7 is an axial sectional view of the hydraulic motor shown in FIGS. 1 to 6 based on the first configuration.

FIG. 8 is an axial sectional view of the hydraulic motor shown in FIGS. 1 to 6 based on the second configuration.

[Explanation of symbols]

2 Auxiliary pump 9 Tank 14 Housing 23 Passage system 24 Flushing oil connection port 29 Oil drain chamber 30 Oil drain port 34, 50 Pump device 43, 57 Two-way valve 51, 5
6 three-way valve

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location F04B 49/00 341 9131-3H (72) Inventor Berner Hermann Federal Republic of Germany Day-7918 Irate Thysen Filechen Beeg 6

Claims (19)

[Claims] 1. A hydraulic machine, in particular an axial piston machine, in which a drive mechanism is incorporated and which includes a housing for collecting waste oil and which is connected to a tank via a drain port A hydraulic machine characterized in that a pump device for sucking the drained oil from the tank is disposed between the drain port and the tank. 2. The pump device is configured to reliably generate a flow rate for sucking the drained oil until the drained oil reaches a level lower than that of a rotating drive mechanism component. 1. The hydraulic machine described in 1. 3. The hydraulic machine according to claim 1 or 2, wherein the pump device is configured to generate a constant flow rate. 4. The hydraulic machine according to claim 1, wherein the pump device is configured to produce an adjustable flow rate. 5. The hydraulic machine according to claim 4, wherein the pump device is controlled with an instantaneous speed of the hydraulic machine as a control parameter in order to adjust a flow rate generated by the pump device. .. 6. The hydraulic pressure according to claim 4, wherein the pump device is controlled by using an instantaneous operating pressure of the hydraulic machine as a control parameter in order to adjust a flow rate generated by the pump device. machine. 7. The pump device is controlled with the flow rate generated or consumed by the hydraulic machine as a parameter in order to adjust the flow rate generated by the pump device. The described hydraulic machine. 8. The hydraulic machine according to claim 4, wherein the pump device includes a jet pump. 9. The working medium connection port of the jet pump comprises:
9. The hydraulic machine according to claim 8, which is connected to a working medium source that generates a flow rate corresponding to the flow rate of the hydraulic machine. 10. The hydraulic machine according to claim 9, wherein the working medium connection port of the jet pump is connected to an operating pressure line connected to the hydraulic machine. 11. The hydraulic machine according to claim 9, wherein the working medium connection port of the jet pump is connected to an auxiliary pump connected to the hydraulic machine. 12. The hydraulic machine according to claim 1, further comprising a valve device having two switching positions for switching the pump device between on and off. 13. Two pieces for connecting and disconnecting flushing oil supply to and from the hydraulic machine, including a flushing oil connection port which is guided to the bearing for the drive mechanism through a passage system so as to supply lubricating oil to the bearing. The hydraulic machine according to any one of claims 1 to 12, wherein the hydraulic machine is connected to another valve device having the switching position of. 14. The function of the two valve devices is combined with a two-way valve arranged between the working medium source for the jet pump and the flushing oil connection port of the hydraulic machine. Any one of claims 8, 12 and 13
The hydraulic machine according to the item. 15. The hydraulic machine according to claim 1, wherein the pump device comprises a positive displacement pump. 16. A valve device formed as a three-way valve in an oil drain line connecting the oil drain port of the hydraulic machine to the tank, the three-way valve connecting the oil drain line in one switching position. 16. The hydraulic machine according to claim 15, wherein the hydraulic machine is connected to a suction port of the positive displacement pump and is connected to the tank at the other switching position. 17. The pump device comprises a throttle control valve for controlling, based on a control parameter, the flow rate produced by the positive displacement positive displacement pump, which is formed as a metering pump. Hydraulic machine described in. 18. An additional throttling element connected to a flushing port of said hydraulic machine for controlling the supply of flushing oil to said hydraulic machine based on control parameters. Or the hydraulic machine according to item 15. 19. The hydraulic machine according to claim 1, further comprising a ventilation device.