DE102010006895A1 - Axial piston machine and control mirror - Google Patents

Abstract

An axial piston machine is disclosed with a relief field that can be controlled as a function of the operating mode.

Description

The invention relates to an axial piston machine according to the preamble of claim 1 and a suitable for such axial piston machine control mirror.

The basic structure of such axial piston machines is known from the prior art, for example the data sheet RD 92 711 / 10.07 (variable displacement pump A10VSO) given by the Bosch Rexroth AG, so that only the components essential for understanding the invention are explained here. Such axial piston machine is preferably carried out adjustable and has a cylindrical drum in which a plurality of cylinder bores is formed, in which pistons are guided axially displaceable. In axial piston machines of the abovementioned type, end sections of the pistons abut against a swashplate whose swivel angle can be made adjustable in order to adjust the delivery / displacement volume. Each of the pistons delimits a cylindrical space in sections, which can be connected alternately to a high-pressure and low-pressure connection formed in a connecting plate via a control mirror abutting the cylindrical drum during rotation of the cylindrical drum.

Such axial piston machine can be operated both as a hydraulic pump and as a hydraulic motor. Due to the functional principle of such axial piston machines, the cylinder drum is pressed with a comparatively high force against the fixed control mirror, so that considerable wear can occur during operation of the axial piston machine in the contact region. To reduce this wear, an axial projection is designed in the case of the axial piston machine known from the data sheet on the end face of the cylinder drum, whose end face can be subjected to high pressure, so that the cylinder drum is supported hydrostatically on the control mirror. The end face of the annular projection thus acts as a relief field, which counteracts the contact force of the cylinder drum and thus reduces wear.

Such relief fields are also in the documents DE AS 1 126 735 . DE AS 1 291 632 . DE PS 941 246 . DE AS 1 528 471 and DE 195 39 442 A1 disclosed.

In these solutions, the relief fields are formed in different geometry as a pressure medium acted projections or grooves.

If such axial piston machines operated as a pump, the above-mentioned contact pressure of the cylinder drum is amplified to the control mirror by the frictional forces of the pressurized piston ausschiebenden pressure. When operating as a motor, the pistons are moved away from the control mirror by the high pressure, so that these frictional forces counteract the force acting on the cylinder pressing force, so that it is reduced.

If the effective area of the relief fields is now based on the pump operation, then, in the case of engine operation, due to the additional relief from the piston moving away from the control plate, the cylinder drum may already lift off the control plate at low rotational speeds and thus cause a malfunction of the axial piston engine come. In order to eliminate such errors, depending on the determination of the axial piston cylinder drums with different relief fields are provided, wherein the discharge field for a motor is smaller than that for a pump.

On the one hand, such a solution has the disadvantage that different cylinder drums must be kept ready for each machine, and that a hydraulic machine designed for pump operation can not be used as an engine or only in certain operating states.

In contrast, the invention has for its object to provide an axial piston machine which can be used in a wide operating ranges both as a motor and as a pump. Another object of the invention is to provide a control plate suitable for such an axial piston machine.

This object is achieved with respect to the axial piston machine by the feature combination of claim 1 and with respect to the control disk by the feature combination of the independent claim 11.

Advantageous developments of the invention are the subject of the dependent claims.

According to the invention, the axial piston machine has a rotatably mounted cylinder drum, in which a plurality of cylinder chambers is formed, which is bounded in each case by a piston. The cylinder drum is located on the front side of a control mirror, via which the cylinder chambers during rotation alternately with high or low pressure can be connected. In the contact area between the cylinder drum and the control mirror, a relief field for reducing the surface pressure between the cylinder drum and the control mirror is provided. According to the invention, this discharge field can be depressurized as a function of the operating mode of the axial piston machine (pump / motor) or the pressure acting on the discharge field can be reduced.

By this measure, the relief pressure in a simple manner depending on the operating mode (pump / motor) can be changed so that the above-described lifting of the cylinder drum from the control mirror during engine operation is not to be feared and on the other hand also in pump operation excessive surface pressure and thus premature wear the cylinder drum or the control mirror can be prevented. This reversal can also take place during the operation of the axial piston machine, so that it can be operated in a regenerative system in which the machine is operated in 4-quadrant operation in which the flow direction of the pressure medium and the high and low pressure side can change.

In a particularly preferred embodiment, the control unit is designed with a switchable or continuously adjustable valve device, via which the discharge field with low pressure, high pressure or other pressure can be acted upon to provide the desired discharge.

In a particularly preferred embodiment, a main relief field is provided in addition to the controllable discharge field, wherein the discharge field is switched without pressure in engine operation.

According to the invention, it is particularly preferred if the sum of the effective areas of the relief field and the main relief field is slightly larger than the pressurized total area of the pistons of the axial piston machine and this total piston area is again larger than the effective area of the main relief field. These area ratios ensure that no excessive relief takes place during operation as a motor and there is sufficient relief during pump operation.

According to an advantageous embodiment, these relief surfaces are formed on the control mirror. This has the advantage that the relief surface does not rotate and thus is stationary with respect to the high-pressure region, so that asymmetric relief field geometries can be realized, which are designed with regard to the optimal discharge.

It is preferred if the main relief field is designed as an annular projection on the control mirror, in which the high-pressure and low-pressure control kidneys. lead. The relief field may then be arranged radially offset from the high-pressure control.

By means of a radially outer arrangement of the relief field, in addition to the reduction of the surface pressure, tilting of the cylinder drum during pump operation can still be prevented or at least shifted to higher rotational speeds. This tilting is a well-known phenomenon where, at high speeds and low pressure, the cylinder lifts off the control level during pump operation and then tilts due to the higher pressure in the area of the high pressure side. To increase the Abhebedrehzahl a support edge is introduced in the case of the axial piston described in RD data sheet on the cylinder, which moves the pivot point for tilting the cylinder further outwards, so that it is better supported. Due to the radially outer relief field, the function of the support edge can be taken with, so that tilting of the cylinder is reduced or at least shifted to higher speed ranges.

The pressure medium supply of the discharge field is preferably via the main discharge field or via its own pressure medium supply.

The pressure medium connection between main relief field and discharge field can also be done externally via the valve device.

In hydraulic machines to be used in 4-quadrant operation, each direction of rotation can be assigned a discharge field, which are then preferably arranged diametrically opposite each other.

For optimum control of the relief fields, the control device can be designed with a device for detecting the pressure medium flow direction and the position of the high pressure side. By this embodiment of the control device can be detected whether the hydraulic machine runs in pump mode or in engine operation and then according to the discharge field with high pressure or low pressure are applied to control the appropriate discharge.

Another advantage of the invention is that the relieving force can be continuously controlled by appropriate pressure control and design of the relief surfaces, so that a leakage oil flow, the efficiency of the hydraulic machine, the wear of the hydraulic machine and the unwanted lifting of the cylinder in the sense of "Condition Monitoring" monitored and the hydraulic machine can be controlled accordingly.

As will be explained in more detail below, a cylinder lift-off protection can also be realized via the controllable relief field, so that Casing pressure peaks can be reduced or prevented.

Preferred embodiments of the invention are explained in more detail below with reference to schematic drawings. Show it:

1 a schematic longitudinal section through an adjustable axial piston machine;

2 a control mirror of the axial piston from 1 in a plan view and a sectional side view;

3 a circuit diagram for controlling a relief field of the control mirror off 2 ;

4 a variant of a control mirror with appropriate control of the discharge field;

5 a modification of the embodiment 4 ;

6 a variant of the embodiment according to 3 for the realization of a cylinder lift-off protection;

7 a control mirror with two controllable discharge fields and appropriate control and

8th an electro-hydraulic control with the function of the embodiment of 7 ,

1 shows a highly simplified sectional view of an axial piston machine of the type A10VO, the structure of which is explained here only to the extent necessary for understanding the invention. The axial piston machine 1 according to 1 is designed in swashplate design. In principle, the invention is also transferable to other types, such as a bent axis unit.

The axial piston machine 1 has an engine 2 with a cylinder drum 4 , in their cylinder bores 6 one piston each 8th is guided axially displaceable. Every piston 8th limited with the cylinder bore 6 a cylinder space 10 , In the 1 right end face 12 the cylinder drum 4 is at a control mirror 14 supported by its high pressure control kidneys 16 and low pressure control kidneys 18 the cylinder chambers 10 alternating with one in a connection plate 20 executed high pressure connection 22 or low pressure connection 24 are connectable.

The engine 2 also has a wave 26 , which serves as a drive or output shaft depending on the operating mode. The wave 26 is non-rotatable with the cylinder drum 4 connected and via a bearing assembly 28 , For example, angular contact bearings in a housing 30 the axial piston machine 1 stored, the front side through the connection plate 20 is closed.

The adjustment of the delivery / absorption volume of the axial piston machine 1 takes place via a swash plate 32 at which the pistons 8th are supported. This is a piston foot 34 every piston 8th spherical and articulated with a sliding shoe 36 connected, on the obliquely inclined swash plate 32 slides. The adjustment of the angle of attack of the swashplate 32 and thus the stroke of the pistons 8th is via an adjustment 38 set, which consists essentially of a setting cylinder 40 and a reset device 42 consists. The latter acts on the swash plate 32 in the direction of their maximum adjustment angle. Adjusting the swash plate 32 takes place by pressurization of the adjusting cylinder 40 , so that the delivery / intake volume by resetting the swash plate 32 can be adjusted to 0 in a position radially to the shaft axis.

For a given direction of rotation can be achieved by pivoting the swash plate 32 be changed over from 0 from the illustrated position from pump to motor mode or vice versa. It is assumed that the axial piston machine 1 at given speed in the in 1 shown swivel position of the swash plate 32 running in pump mode. By pivoting the swashplate 32 Beyond 0, then the pump operation can be adjusted, this pivoting against the force of the return cylinder 42 takes place and this enters accordingly. This movement can - as will be explained below - be exploited for the inventive control of the relief fields.

2 shows a plan view of the cylinder drum 4 forth on an embodiment of the control mirror 14 as he according to a construction 1 is usable. In 2 Furthermore, above, a section along the line AA is shown, this sectional view is not a true-to-scale view but shown in the vertical direction compared to the real design increased to facilitate understanding.

The control mirror 14 is designed annular and surrounds with its inner diameter 44 the bearing arrangement 28 the wave 26 , In the annulus area is the circular segment-shaped, comparatively long ND-control animals 18 and a variety of comparatively short, HD-control 16 educated. The latter HD control 16 open in the connection plate 20 and are in fluid communication with the HD port 22 , Accordingly, the long ND control animals 18 in the connecting plate 20 with the ND connection 24 connected. In the illustrated embodiment, there are five spaced-apart HD controls 16 provided, of course, number and geometry can also be changed.

Between the HD-control 16 and the ND control animals 18 there are two bars each 46 . 48 that correspond to the top and bottom dead center, respectively. In the transition area between the LP-control animals 18 and the jetty 46 and HD-controlling 16 and the jetty 48 is each a damping slot 50 respectively. 52 formed over which the Umsteuervorgang in the region of the webs 46 . 48 is dampened. In the area of these footbridges 46 . 48 the pistons are in their upper and lower dead center.

As can be seen in particular from the section AA, is in by the kidneys 16 . 18 formed area an annular projection 54 formed, the annular end face 56 a main relief field 56 forms, along which the end face 12 the cylinder drum 4 slides.

On the high pressure side (HD control 16 ) is in the range of the outer circumference of the control mirror 14 one to the cylinder drum 4 projecting relief field 58 formed, which is designed in the illustrated variant as an approximately rectangular, slightly curved frame structure, which is a bag 60 embraces. The axial height of the relief field 58 corresponds to the axial height of the main relief field 56 so the frontal area 12 the cylinder drum 4 also along the relief field 58 slides.

In 2 is with a point 62 a pressure medium supply for the bag 60 indicated. During the circulation of the cylinder drum 4 along the control mirror 14 occurs over the high-pressure kidneys 16 Pressure medium in the gap between the main relief field 56 and the face 12 the cylinder drum 4 one, leaving the cylinder drum 4 is relieved by this relief pressure and thus premature wear of the face 12 or the control mirror 14 is prevented. This relief is essentially through the annular surface of the projection 54 determined, so that a comparatively simple adjustment of the unloading force by varying the inner and outer diameter of the projection 54 is possible. The much smaller relief surface 58 can over the indicated own pressure medium supply 62 or by the pressure medium connection with the main relief field 56 also be subjected to high pressure, so that this much smaller discharge field also to relieve the cylinder drum 4 contributes. As will be explained in more detail below, the relief field 58 be depressurized via a suitable valve device in engine operation, so that then only the main discharge field 56 contributes to cylinder relief and thus the above-described lifting the cylinder drum 4 can be avoided. In pump operation, the discharge field becomes 58 subjected to high pressure via this valve device, so that the required in the pump operation higher cylinder relief is ensured. In this way, it is possible to use the axial piston machine without changing the components, both in pump operation and in engine operation, without having to fear functional disadvantages.

The activation of the relief field 58 will be explained with reference to some embodiments.

3 shows a variant in which the on the HD-control 16 applied pressure via a supply channel 64 between a constant throttle 66 and an adjustable throttle 72 (Pressure divider) is tapped, which are connected in series. Depending on the setting of the adjustable throttle 72 can the pressure in the supply line 64 leading to the discharge field 58 more precisely in the pocket seized by this 60 leads to be set. This pressure can correspond to the high pressure (adjustable throttle 72 completely closed) or take an almost arbitrary pressure value, which is smaller than the high pressure and greater than the low pressure ND.

The pressure in the supply channel 64 can via a pressure gauge 68 are displayed. From the supply channel 64 branches a discharge channel 70 from which is connected to a low pressure leading pressure chamber ND and in which the adjustable throttle 72 is arranged. In the area between the HD-control animals 16 and the first throttle 66 is a relief valve 74 arranged, which is designed in this embodiment as a 2/2-way valve and is biased by a spring in an open position and is mechanically switched to a blocking position to the pressure medium connection between the HD-Steuiere 16 or the main relief field 56 and the discharge field 58 shut off.

This operation can be done via control parts, not shown. In principle, it is also possible on the basis of 1 explained return cylinder 42 so that this is the function of the relief valve 74 takes over and thus the supply channel 64 on or off. The pivoting of the swash plate 32 would then be with a switching of the switching valve 74 according to 3 equate.

A concrete solution to this concept is in 1 dashed lines. The return cylinder 42 is in pump mode in direction "-a" in 1 extended. To change the engine operation is the swash plate 32 when retracting the Reset cylinder 32 pivoted in the direction of "-a". When retracting a piston moves 41 one. The cylinder-side end portion of the piston 41 is in the illustration according to 1 shown in dashed lines. Its face 43 limited inside the return cylinder 42 a pressure room 45 , which is acted upon by an unillustrated line with HD. This pressure room 45 is over one or more radial bores 47 with the in 1 indicated supply channel 64 connected. Both adjustment of the piston 41 in direction "-a" (motor operation) passes over the front side 43 of the piston 41 this radial bore 47 so that the connection of the supply channel 64 to the HD is shut off. That is, the piston 41 of the return cylinder 42 takes over in cooperation with the radial bore 47 the function of in 3 shown switching valve 74 , By this switching is the pressure medium connection of the discharge field 58 interrupted to the high pressure and the pressure medium can via the relief throttle 72 to the low pressure. At the same time, there is also relief via the leaked leak oil 62 , so that the relief field is depressurized and thus only the main relief field 56 is effective.

The channels described above 64 . 70 can in any way in the control mirror 14 , the cylinder drum 4 , the connection plate 20 or in the case 30 be educated. Of course, it is also possible to switch the relief valve 74 in another way, for example, perform electrical / electro-hydraulically via a controller.

4 shows an embodiment of the control mirror 14 in which the main relief field 56 directly with the discharge field 58 is connected, ie in this embodiment falls in 2 right inner circumferential wall of the frame-shaped relief field 58 with the corresponding section of the projection 54 together so that the supply channel according to 3 can be omitted. The discharge channel 70 flows with this variant directly into the bag 60 one. The pocket 60 is beyond the scope of the relief box 58 filled with pressure medium, which faces the high pressure side. The pressure medium discharge takes place via the low-pressure side peripheral areas of the relief field 58 so in the bag 60 in about the same pressure as at the discharge field 58 is applied.

The relief valve 74 is in the discharge channel in this embodiment 70 arranged and biased by the spring into a blocking position to the discharge field 58 to apply high pressure during pump operation. In engine operation, the relief valve 74 switched to the open position, leaving the discharge field 58 is depressurized while the main relief field 56 continue on HD-control 16 subjected to high pressure.

At the in 4 illustrated embodiment is the relief valve 74 in turn mechanically actuated (see comments on the embodiment according to 3 ). As in 5 shown, instead of the mechanically operated directional control valve, an electrically or electro-hydraulically operated relief valve 74 be used. This is in the illustrated embodiment, a proportionally adjustable pressure relief valve for controlling the pressure in the discharge channel 70 and thus at the discharge field 58 , Of course, such a proportionally adjustable control valve can also be used in the other solutions described here.

As already explained at the beginning, the cylinder drum tends 4 of the engine 2 in pump mode at high speeds and low pressure to lift off the control plate 14 , The cylinder drum tilts 4 due to the frictional forces of the extending pistons 8th on the low pressure side around the high pressure side, ie in the 2 . 3 and 4 left side of the control mirror 14 , This tilting movement is due to the discharge field effective during pump operation 58 diminished, leaving the cylinder drum 4 hydrostatically supported and thus the Abhebedrehzahl is shifted upwards.

In conventional solutions, this tilting by providing an outer support edge on the cylinder drum 4 prevented.

In 6 is a modification of the embodiment according to 3 shown. In this variant, the supply channel 64 via a message channel 80 led to the low pressure side to a tilting movement of the cylinder drum 4 to be able to record better. This is possible because in this low-pressure side region, the larger gap results, which in turn on the leakage oil in the bore 82 to a significant pressure drop in the discharge field 58 leads. In other words, due to the increased leakage oil flow, the pressure drops in the area of the bore 82 and thus the pressure at the discharge field 58 from. This reduces accordingly the unloading force with the result that the cylinder drum 4 again stronger to the control mirror 14 is pressed. The causal sequence is then determined by the chain: leakage oil change → pressure change → discharge change. The circuit according to 6 thus corresponds to a hydraulic lift-off. In the embodiment according to 6 is the relief valve 74 not shown - this can of course also be provided in this variant.

If rapid load and direction changes are to be controlled via the hydraulic machine, as may occur, for example, during reversing, the hydraulic machines, which are then preferably designed as constant units, are operated in 4-quadrant operation. This means that when reversing high-pressure and low-pressure side at the connections of the hydraulic machine and also change according to the flow direction in the hydraulic machine. For the solution according to the invention this requires accordingly to detect the flow direction and the high-pressure / low-pressure side and to control the discharge field as a function of these characteristics. 7 shows a hydraulic embodiment of such a solution. Here is the control mirror 14 with two relief fields arranged diametrically opposite one another 58a . 58b executed, the basic structure of the embodiment according to the 3 and 6 corresponds so that further explanations are dispensable. The right in the figures arranged Steuiere is not by a comparatively long circle segment section but like the HD Steuerieren 16 by a plurality of smaller, spaced apart control kidneys 18 formed the same division as the control 16 exhibit. In pump operation, depending on the position of the high pressure side and flow direction of the relief fields 58a . 58b subjected to the relief pressure and the other. relief field 58b . 58a depressurized. This can be done, for example, by a circuit according to 7 take place, which has a symmetrical structure.

The Steering 16 . 18 are over in 1 illustrated connection plate 20 connected to the two terminals A, B, said pressure medium connection via channels 84 . 86 takes place, in which each aperture 88 . 90 are arranged. The pressure in the channels 84 . 86 becomes the input of a shuttle valve 91 led, whose output to the supply channel 64 is connected, in which the throttle 66 is arranged. The supply channel 64 Branches in the embodiment according to 7 in two supply channel branches 64a . 64b , each to the entrance of a relief valve 74a . 74b to lead. This is designed as a 3/2-way valve, wherein an output terminal A via a channel section 92a . 92b with the respective discharge field 58a . 58b or more precisely, the pocket grabbed 60a . 60b connected is. The third port T is connected to the low pressure ND. The relief valve 74a . 74b is biased to a home position in which the pressure port P is shut off and the duct section 92a . 92b is connected to the low pressure ND (tank). In the direction of the switching position in which the pressure port P is connected to the working port A, the two relief valves 74a . 74b each from the pressure in the assigned channel 84 . 86 acted upon by a control line 96a . 96b is tapped.

In the area between the inputs of the shuttle valve 91 and the control animals 16 . 18 branches in each case a bypass channel 98a . 98b starting from the respective aperture 88 . 90 bypasses and in which a pilot-operated check valve 100a . 100b is arranged by the pressure in the other bypass channel 98b . 98a is unlockable. In the unlocked position leaves the check valve 100a . 100b a pressure fluid flow in the direction of the terminals A and B, wherein the respective aperture 88 . 90 is bypassed. The pressure downstream of the irises 88 . 90 or in the junction area of the bypass channel 98a . 98b in the working channel 84 . 86 is via a control channel 102 . 102b tapped and to an effective in the closing direction control surface of the other relief valve 74a . 74b reported.

As in 7 is further shown, is the supply channel 64 downstream of the branch to the channel sections 64a . 64b over the adjustable throttle 72 connected to the low pressure ND (tank).

It is now assumed that the axial piston machine 1 runs in pump mode, where at port A, the high pressure is applied and port B is the suction side (ND). Due to the higher pressure in the channel 84 becomes the relief valve 74a switched to its passage position, in which the supply duct section 64a with the channel section 92a connected is. The pressure medium can then from the high pressure side via the shuttle valve 91 , the supply channel 64 and the supply channel section 64a as well as the canal section 92a to the relief field 58a flow, so that the high pressure is applied to this. The relief valve remains 74b in its spring preloaded basic position, so that in 7 right discharge field 58b relieved to low pressure ND out. Due to the high pressure in the channel 84 becomes the low-pressure side check valve 100b unlocked. With the check valve open 100b lies on both sides of the relief valve 74b the same control pressure, so that this is biased by the force of the spring to its basic position, in the relief field 58b relieved to the ND. The direction of flow is above the pressure drop across the orifice 88 (or 90 ) detected.

The function in motor operation is appropriate. In principle, the structure according to the 6 and 7 designed for a 4-quadrant operation with the associated pressure side changes and flow direction changes (pump / motor).

As stated, can be such a control arrangement, both the flow direction of the Pressure fluid and the position of the high pressure side detected and depending on these parameters, the relief surfaces 58a . 58b to be controlled.

8th shows an electro-hydraulic solution with respect to the embodiment according to 7 simplified structure.

The structure of the control mirror 14 is the same as in the embodiment according to 7 ie there are two relief fields 58a . 58b provided and the high-pressure or low-pressure side steer 16 . 18 are performed by a total of five, lying on a common circle relatively small kidneys. Depending on the mode of operation of the axial piston machine, these relief fields 58a . 58b be controlled via a controller.

The connections A, B are again via channels 84 . 86 in the connection plate 20 connected to the high pressure side and the low pressure side. The pressure in these two channels 84 . 86 is located at the entrances of the shuttle valve 91 whose output is via the supply channel 64 and the throttle 66 with the supply channel branches 64a . 64b connected to each one of the relief fields 58a . 58b to lead. The supply channel branches 64a . 64b are over the discharge channel 70 and the adjustable throttle 72 connected to the ND.

In the supply channel branches 64a . 64b is in each case an electrically or electro-hydraulically adjustable relief valve 74a . 74b provided, which is controlled in dependence on the speed and the position of the high-pressure field and the operating mode (pump, motor) to the respective discharge field 58a . 58b pressurize or relieve pressure. In a similar way, the control of the relief valves 74a . 74b also done to tilt or lift the cylinder drum 4 to prevent or at least to move in higher speed ranges.

The two relief valves 74a . 74b are also designed as 2/2-way valves, with the discharge fields 58a . 58b in the spring-biased home position of these relief valves 74a . 74b are placed on low pressure. In line with each relief valve 74a . 74b is a 2/2-way switching valve 102 . 102b provided, which is biased into a closed position and the pressure in the channels 84 . 86 is switchable. This pressure is via a control channel 104a . 104 b tapped. In the case where the port A is pressurized (control 16 are HD kidneys), will be the switching valve 102 switched and the discharge field 58a over the shuttle valve 91 , the throttle 66 , the supply channel 64 , the supply duct section 64a and the relief valve controlled by the control 74 subjected to the high pressure. The then located in the low pressure branch switching valve 102b stays in its spring biased blocking position, leaving the other relief field 58b relieved of pressure.

The flow direction of the pressure medium is over the direction of rotation of the cylinder drum 4 certainly. This is detected by a suitable sensor and reported to the controller, so that this depending on the direction of rotation or more precisely from the pressure fluid flow direction and the operating state, a suitable signal to the supply valves 74a . 74b can deliver.

Disclosed is an axial piston machine with a controllable depending on the operating mode discharge field.

LIST OF REFERENCE NUMBERS

1

axial piston

2

engine

4

cylinder drum

6

bore

8th

piston

10

cylinder space

12

front

14

A control plate

16

Control HD

18

Control ND

20

connecting plate

22

HD connection

24

ND connection

26

wave

28

bearing arrangement

30

casing

32

swash plate

34

piston base

36

shoe

38

Reset device

40

adjusting cylinder

41

piston

42

Reset cylinder

43

front

44

Inner diameter

45

pressure chamber

46

web

47

radial bore

48

web

50

damping slot

52

damping slot

54

head Start

56

Main relief field

58

relief field

60

bag

62

Pressure medium supply

64

supply channel

66

throttle

68

Pressure transducer

70

relief channel

72

throttle

74

relief valve

76

connecting region

78

connecting region

80

signaling channel

82

drilling

84

channel

86

channel

88

cover

90

cover

91

shuttle valve

92

channel section

94

channel section

96

control line

98

bypass channel

100

check valve

102

switching valve

104

control channel

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 1126735 [0004]
• DE 1291632 [0004]
• DE 941246 [0004]
• DE 1528471 [0004]
• DE 19539442 A1 [0004]

Claims (11)

Axial piston machine with a rotatably mounted cylindrical drum ( 4 ) in which a plurality of each by a piston ( 8th ) Sectionally limited cylinder spaces ( 10 ) are formed during the rotation of the cylinder drum ( 4 ) via one on a front side ( 12 ) of the cylinder drum ( 4 ) adjacent control mirror ( 14 ) are connectable to high pressure (HD) or low pressure (ND), and to a relief field loaded with a relief pressure (N) ( 58 ) for reducing the surface pressure between the cylinder drum ( 4 ) and control mirrors ( 14 ), characterized by a control device via which the discharge field ( 58 ) can be relieved depending on the operating mode. Axial piston machine according to claim 1, wherein the control device comprises a continuously adjustable or switchable valve device ( 74 ), through which the discharge field ( 58 ) with low pressure (ND) or high pressure (HD) can be acted upon. Axial piston machine according to one of the preceding claims, wherein in addition to the controllable discharge field ( 58 ) a main relief field ( 56 ) is provided. Axial piston machine according to claim 3, wherein the sum of the effective surfaces of the relief field ( 58 ) and the main relief field ( 56 ) slightly larger than the total pressurized area of the pistons ( 8th ) and this total area in turn larger than the effective area of the main relief field ( 56 ). Axial piston machine according to one of the preceding claims, wherein the relief field ( 58 . 56 ) at the control mirror ( 14 ) is trained. Axial piston machine according to claim 5, wherein the main relief field ( 56 ) as an annular projection ( 54 ), in which the control animals ( 16 . 18 ) and / or the discharge field ( 58 ) radially offset to the high-pressure side control kidneys ( 16 ) is arranged. Axial piston machine according to one of the claims 3 to 6, wherein the relief field ( 58 ) hydraulically with the main relief field ( 56 ) or has its own pressure medium supply. Axial piston machine according to claim 2 or one of the claims related thereto, wherein the pressure medium supply externally via the valve device ( 74 ), he follows. Axial piston machine according to one of the preceding claims, wherein each direction of rotation of the cylinder drum ( 4 ) a relief field ( 58a . 58b ) assigned. Axial piston machine according to claim 9, wherein the control device has a device for detecting the pressure fluid flow direction and the position of the high pressure side. Control plate for an axial piston machine according to one of the preceding claims, comprising a plurality of control rods ( 16 . 18 ) and one in the field of 16 . 18 ) trained main relief field ( 56 ) as well as a radially offset relief field ( 58 ) whose size is much smaller than that of the main relief field ( 56 ).

Images