Hydrostatic axial piston machine having pressure side change

Abstract

There is disclosed a hydrostatic axial piston machine having a pulse reduction device. This device has a connection location or tap in the transition region in front of the high-pressure-side kidney-like elongate hole of a distributor plate. The connection location or tap is connected by means of one or two hydraulically passively controlled switching valves to a high-pressure store. It is used for precompression and consequently for the pulse reduction. In a development, the distributor plate also has a connection location or tap in the transition region behind the high-pressure-side kidney-like elongate hole. The connection location or tap is connected via one or two hydraulically passively controlled switching valves to a low-pressure store. This is used for the decompression and consequently also for the pulse reduction.

Claims

1. A hydrostatic axial piston machine comprising: a rotating cylinder drum; a plurality of cylinders formed in the rotating cylinder drum, each of the plurality of cylinders connected by a respective opening to an end face of the rotating cylinder drum; a distributor plate including a first circular-arc-like elongate hole and a second circular-arc-like elongate hole, wherein each of the plurality openings is configured to move along a circular path, and the end face is tensioned against the distributor plate, a first connection location provided in a first transition region between the two elongate holes and adjacent to the first elongate hole, and a second connection location provided in a second transition region between the two elongate holes and adjacent to the second elongate hole; a first switching valve arrangement; a high-pressure store; and a first and a second control pressure line operably connected to the first switching valve and configured such that when the first circular-arc-like elongate hole is acted on with high pressure, the first connection location is connected to the high-pressure store through the first switching valve and the second connection location is blocked from the high-pressure store by the first switching valve, and when the second circular-arc-like elongate hole is acted on with high pressure, the second connection location is connected to the high-pressure store through the first switching valve and the first connection location is blocked from the high-pressure store by the first switching valve.

2. The hydrostatic axial piston machine according to claim 1, wherein: the first switching valve arrangement comprises a 3/2-way switching valve having a first switching position and a second switching position; in the first switching position the high-pressure store is connected to the first connection location and the second connection location is blocked from the high-pressure store; in the second switching position the high-pressure store is connected to the second connection location and the first connection location is blocked from the high-pressure store; pressure at the first elongate hole acts on a valve body of the 3/2-way switching valve in a direction toward the first switching position; and pressure at the second elongate hole acts on the valve body of the 3/2-way switching valve in a direction toward the second switching position.

3. The hydrostatic axial piston machine according to claim 1, wherein the first switching valve arrangement comprises a first 2/2-way switching valve and a second 2/2-way switching valve: a pressure of the first elongate hole acts on a valve body of the first 2/2-way switching valve in a direction of an open position and a pressure of the second elongate hole acts on the valve body of the first 2/2-way switching valve in a direction of a closure position; and the pressure of the first elongate hole acts on a valve body of the second 2/2-way switching valve in a direction of a closure position and the pressure of the second elongate hole acts on the valve body of the second 2/2-way switching valve in a direction of an open position.

4. The hydrostatic axial piston machine according to claim 2, further comprising: a third connection location in the second transition region adjacent to the first elongate hole; a fourth connection location provided in the first transition region adjacent to the second elongate hole; a second switching valve arrangement; a low-pressure store; and a third and fourth control pressure line operably connected to the second switching valve and configured such that when the first circular-arc-like elongate hole is acted on with high pressure, the third connection location is connected to the low-pressure store through the second switching valve and the fourth connection location is blocked from the low-pressure store by the second switching valve, and when the second circular-arc-like elongate hole is acted on with high pressure, the fourth connection location is connected to the low-pressure store through the second switching valve and the third connection location is blocked from the low-pressure store by the second switching valve.

5. The hydrostatic axial piston machine according to claim 4, wherein: the second switching valve arrangement comprises a further 3/2-way switching valve having a third switching position and a fourth switching position; in the third switching position the low-pressure store is connected to the third connection location and the fourth connection location is blocked from the low-pressure store; in the fourth switching position the low-pressure store is connected to the fourth connection location and the third connection location is blocked from the low-pressure store; pressure at the second elongate hole acts on a valve body of the further 3/2-way switching valve in a direction toward the fourth switching position; and pressure at the first elongate hole acts on the valve body of the further 3/2-way switching valve in a direction toward the third switching position.

6. The hydrostatic axial piston machine according to claim 4, wherein the second switching valve arrangement comprises a third 2/2-way switching valve and a fourth 2/2-way switching valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Two embodiments of an axial piston machine according to the disclosure are illustrated in the Figures, in which:

(2) FIG. 1 is a longitudinal section of significant components of the axial piston machine in which the two embodiments of the disclosure according to FIGS. 1 and 2 are produced,

(3) FIG. 2 shows a distributor plate having a hydraulic circuit diagram in a first embodiment of the disclosure, and

(4) FIG. 3 shows a distributor plate having a hydraulic circuit diagram in a second embodiment of the disclosure.

DETAILED DESCRIPTION

(5) FIG. 1 is a schematic, sectioned view of significant components of an axial piston machine of the swash plate construction type. A cylinder drum 1 is coupled to a drive shaft 2 in a rotationally secure manner so that they rotate together. Along the drive shaft 2, there extend in the cylinder drum 1 cylinders 4 which are distributed in a uniform manner over the periphery and in which pistons 6 are displaceably guided. The pistons 6 are coupled by means of respective piston bases and sliding blocks which rotate therewith to a stationary swash plate 8 which is positioned in an oblique manner with respect to the drive shaft 2. Therefore, with each rotation about the drive shaft 2, each piston 6 carries out a stroke, the size of which is dependent on the oblique position of the swash plate 8.

(6) At an end face of the cylinder drum 1 at the side opposite the swash plate 8 for each cylinder 4 there is provided an opening 10 which is connected to the respective cylinder 4 by means of a respective connection channel 11. The end face rotates and is tensioned with the peripheral openings 10 thereof against a stationary distributor plate 12; 112 which is secured to a housing (not illustrated) of the axial piston machine.

(7) FIGS. 2 and 3 each show such a distributor plate 12; 112. It can be seen that the distributor plates 12; 112 have circular-arc-like or kidney-like elongate holes A, B. Depending on the operating state, one of the elongate holes A, B is at the high-pressure side and the other elongate hole B, A is at the low-pressure side. The peripheral openings 10 are guided along a circular path 14 in a sealed manner via these elongate holes A, B.

(8) In FIGS. 2 and 3, a rotation or a revolution of the openings 10 (cf. FIG. 1) along the circular path 14 in a counter-clockwise direction is assumed and it is further assumed that the first elongate hole B is at the high-pressure side, whilst the second elongate hole A is at the low-pressure side. When viewed in a peripheral direction, a planar first transition region 16 is provided behind the low-pressure-side second elongate hole A and in front of the high-pressure-side first elongate hole B, whilst diametrically opposite a second transition region 18 is provided behind the high-pressure-side first elongate hole B and in front of the low-pressure-side second elongate hole A. The two transition regions 16, 18 seal the respective opening 10 and consequently the respective cylinders 4 according to the prior art with respect to a housing interior.

(9) According to FIGS. 2 and 3, a first connection location 20 is provided in the first transition region 16 in a peripheral direction directly in front of the first high-pressure-side elongate hole B, whilst a second connection location 2 is provided in the peripheral direction directly in front of the low-pressure-side second elongate hole A. The two connection locations 20, 22 are constructed as small holes perpendicularly to the surface of the distributor plate 12 and thus act as openings which are moved into fluidic contact with the openings 10 of the cylinders 4 which run over them (cf. FIG. 1).

(10) According to the first embodiment from FIG. 2, the two connection locations 20, 22 are connected by means of a respective precompression line 24 to a common 3/2-way switching valve 26. A valve body of the 3/2-way switching valve 26 is acted on by means of a control pressure line 28 with the operating pressure of the first high-pressure-side elongate hole B in the direction of the switching position a (shown in FIG. 2), in which a high-pressure store HD is connected to the first connection location 20. In contrast, the valve body of the 3/2-way switching valve 26 is acted on via a control line 28 with the pressure of the second low-pressure-side elongate hole A in the direction of a switching position b, in which the second connection location 22 is connected to the high-pressure store HD.

(11) A switching of the 3/2-way switching valve 26 is carried out in a passive and automatic manner if the second elongate hole A is intended to be acted on with high pressure, whilst the first elongate hole B is acted on with low pressure. Consequently, the second connection location 22 is connected to the high-pressure store HD so that the compression of the openings 10 which run in a counter-clockwise direction (cf. FIG. 1) is carried out before reaching the second elongate hole A.

(12) In principle, the second embodiment from FIG. 3 is consequently comparable in terms of function with the first embodiment of FIG. 2 as described until this point. In this instance, in FIG. 3, the 3/2-way switching valve 26 from FIG. 2 is replaced by two 2/2-way switching valves 126a, 126b which are separated from each other. The first 2/2-way switching valve 126a connects the first connection location 20 which, when viewed in a peripheral direction, is arranged directly in front of the high-pressure-conducting first elongate hole B to the high-pressure store HD. The second 2/2-way switching valve 126b locks in this instance the second connection location 22 which is arranged in a peripheral direction in front of the low-pressure-side second elongate hole A with respect to the high-pressure store HD. To this end, both 2/2-way switching valves 126a, 126b have a connection via a control pressure line 28 to the first elongate hole B and to the second elongate hole A.

(13) Also, in the second embodiment according to FIG. 3, in the event of a pressure side change between the two elongate holes A, B, the second connection location 22 at the input of the now high-pressure-conducting second elongate hole A is connected to the high-pressure store HD, whilst the first connection location 20 is separated from the high-pressure store HD. To this end, both 2/2-way switching valves 126a, 126b switch into the respective switching position not shown in FIG. 3.

(14) With regard to FIG. 2, a second portion of the first embodiment of the pulse reduction device shown is explained. The second portion has a low-pressure store ND, another 3/2-way switching valve 30 with control pressure lines 28 at both sides. Furthermore, a third connection location 32 is provided in the first transition region 16 between the second elongate hole A and the first connection location 20. In a similar manner, a fourth connection location 34 is provided in the second transition region 18 between the first elongate hole B and the second connection location 22. The third connection location 32 and the fourth connection location 34 are also arranged on the circular path 14.

(15) The third connection location 32 and the fourth connection location 34 are connected via a respective decompression line 36 to the additional 3/2-way switching valve 30. With this second portion of the pulse reduction device according to the disclosure, a decompression of the openings 10 or cylinders 4 which move thereover (cf. FIG. 1) in the peripheral direction behind the elongate hole A, B which is acted on with high pressure is brought about. If the first elongate hole B is acted on with high pressure, this decompression takes place at the fourth connection location 34 before the corresponding opening 10 moves over the elongate hole A which is acted on with low pressure. To this end, the additional 3/2-way switching valve 30 is in the switching position a shown in FIG. 2. If a pressure side change takes place and the second elongate hole A is acted on with high pressure, the decompression takes place at the third connection location 32, for which purpose the additional 3/2-way switching valve 30 is moved into the switching position b.

(16) There is disclosed a hydrostatic axial piston machine having a pulse reduction device. This device has a connection location 20, 22 or tap in the transition region 16, 18 in front of the high-pressure-side kidney-like elongate hole A, B of a distributor plate 12; 112. The connection location 20, 22 or tap is connected by means of one or two hydraulically passively controlled switching valves 26; 126a, 126b to a high-pressure store HD. It is used for precompression and consequently for the pulse reduction.

(17) In a development, the distributor plate 12 also has a connection location 32, 34 or tap in the transition region 16, 18 behind the high-pressure-side kidney-like elongate hole A, B. The connection location 32, 24 or tap is connected via one or two hydraulically passively controlled switching valves 30 to a low-pressure store ND. This is used for the decompression and consequently also for the pulse reduction.

LIST OF REFERENCE NUMERALS

(18) 1 Cylinder drum 2 Drive shaft 4 Cylinder 6 Piston 7 Sliding block 8 Swash plate 10 Opening 12;112 Distributor plate 14 Circular path 16 First transition region 18 Second transition region 20 First connection location 22 Second connection location 24 Precompression line 26 3/2-way switching valve 28 Control pressure line 30 (Additional) 3/2-way switching valve 32 Third connection location 34 Fourth connection location 36 Decompression line 126a First 2/2-way switching valve 126b Second 2/2-way switching valve A Second elongate hole B First elongate hole a Switching position b Switching position HD High-pressure store ND Low-pressure store