Axial Piston Machine

Abstract

An axial piston machine for at least one of a pump and a motor operation includes a housing, connection plate, piston drum, and working piston. The connection plate is connected to the housing. The piston drum is arranged on a rotatable drive shaft in the housing interior and defines at least one cylinder bore. The working piston is arranged in a longitudinally displaceable manner in the cylinder bore. The cylinder bore delimits a cylinder space having a changeable volume. The cylinder space is configured to connect to at least one pre-compression space via at least one hydraulic connection. The at least one pre-compression space is defined by a cavity within the connection plate. The cavity is defined by the connection plate and a closing element. The closing element is arranged between the connection plate and the housing interior.

Claims

1. An axial piston machine for at least one of a pump and a motor operation, comprising: a housing; a connection plate connected to the housing; a piston drum arranged on a rotatable drive shaft in the housing interior and defining at least one cylinder bore; and a working piston arranged in a longitudinally displaceable manner in the cylinder bore, wherein the cylinder bore delimits a cylinder space having a changeable volume, wherein the cylinder space configured to be connected to at least one pre-compression space via at least one hydraulic connection, wherein the at least one pre-compression space is defined by a cavity within the connection plate and the cavity is defined by the connection plate and a closing element, and wherein the closing element is arranged between the connection plate and the housing interior.

2. The axial piston machine as claimed in claim 1, wherein the closing element and the connection plate have a mutual contact area.

3. The axial piston machine as claimed in claim 2, wherein the closing element and the connection plate are in direct contact.

4. The axial piston machine as claimed in claim 1, wherein the closing element is a screw.

5. The axial piston machine as claimed in claim 1, wherein a hydraulic attachment to a distributor plate is formed in the connection plate for each pre-compression space.

6. The axial piston machine as claimed in claim 1, wherein the at least one pre-compression space defines a pre-compression volume configured to reduce a hydraulic pulsation of the axial piston machine.

Description

DRAWINGS

[0022] The drawing shows

[0023] FIG. 1: an embodiment of the axial piston machine according to the invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0024] FIG. 1 shows an axial piston machine 100 for pump and/or motor operation in a longitudinal section wherein only one half is shown, having a housing 10, which is screwed to a connection plate 20. A rotatable drive shaft 10 is mounted in the housing 10 and in the connection plate 20. A substantially cylindrical piston drum 30 is arranged on the drive shaft 40 such that it executes the same rotational movement as the drive shaft 40. The connection of the drive shaft 40 and the piston drum 30 is typically effected via a gearing (not illustrated).

[0025] At least one, but preferably seven to eleven, cylinder bores 31 are formed in an axially parallel manner in the piston drum 30. A working piston 32 is arranged in a longitudinally displaceable manner in each cylinder bore 31 and, with the cylinder bore 31, thus delimits a cylinder space 31 having a changeable volume. Accordingly, there are as many working pistons 32 and cylinder spaces 31 as there are cylinder bores 31.

[0026] A pivot cradle 60 is arranged in a non-rotatable manner in the housing 10. The pivot cradle 60 is mounted in a pivotal manner by means of a bearing (not illustrated) so that it can be brought to an adjustment angle □ of greater or less than 90° with respect to the drive shaft 40 with the aid of at least one, but preferably two adjusting units (not illustrated). If the adjustment angle □ is precisely 90° , then the axial piston machine 100 is in idle mode.

[0027] Sliding blocks 62 can slide along the pivot cradle 60, in which sliding blocks the working pistons 32 are mounted by means of a ball bearing; i.e. the number of sliding blocks 62 is equal to the number of working pistons 32. The sliding blocks 62 are held down on the pivot cradle 60 via a device (not illustrated), so that pressure forces are constantly transmitted between the pivot cradle 60 and the working pistons 32.

[0028] A distributor plate 70 is arranged between the rotatable piston drum 30 and the connection plate 20 and fixedly connected to the connection plate 20 so that the piston drum rotates with an end face on the distributor plate 70 or on a dynamic lubricating film which is formed between the two components during operation. A filling bore 75 is formed in the distributor plate 70, which filling bore is hydraulically connected to a hydraulic connection 22 formed in the connection plate 20, wherein the hydraulic connection 22 leads into a pre-compression space 50. The hydraulic connection 22 is designed as a connecting bore or through bore in the embodiment outlined. Alternatively, and depending on the geometric design of the pre-compression space 50, the hydraulic connection 22 can also be produced by other manufacturing methods, for example casting.

[0029] The pre-compression space 50 is formed by a cavity 120 within the connection plate 20 and the cavity 120 is formed by the connection plate 20 and a closing means 90, wherein the closing means 90 is arranged between the connection plate 20 and the housing interior 15.

[0030] The closing means 90 is realized by a screw and this has a contact area 150 with the connection plate 20. The contact area 150 is formed by a surface 220 of the connection plate 20 which faces the housing interior 15 and a bearing area 190 of the screw head on the surface 220 of the connection plate 20. The contact is produced in the screwed-in state.

[0031] A surface 250 formed in the pre-compression space 50 is machined using a milling process and has an internal thread for receiving the screw.

[0032] The number and size of the pre-compression spaces 50 are dependent on the particular application and on the installation space available in the housing 10 and in the connection plate 20.

[0033] At least one low-pressure kidney 71 and at least one high-pressure kidney 72 are furthermore formed in the distributor plate 70. These are connected to a suction kidney 81 and a pressure kidney 82 respectively, which are both formed in the connection plate 20. The suction kidney 81 leads into a low-pressure bore (not illustrated) and the pressure kidney 82 leads into a high-pressure bore (not illustrated) which are likewise both formed in the connection plate 20. At the end opposite the distributor plate 70, the connection plate 20 has a low-pressure connection (not illustrated) and a high-pressure connection (not illustrated). The low-pressure connection connects the low-pressure bore to a low-pressure reservoir (not illustrated) and the high-pressure connection connects the high-pressure bore to a high-pressure reservoir (not illustrated).

[0034] Therefore, different hydraulic connections of a cylinder space 31 are controlled depending on the rotational angle position of the drive shaft 40: [0035] In a first rotational angle position of the drive shaft 40, a first hydraulic connection from the cylinder space 31 via the filling bore 75 and the connection bore 22 into the pre-compression space 50, in particular the low-pressure pre-compression space, is opened. [0036] Then, in a second rotational angle position of the drive shaft 40, a second hydraulic connection from the cylinder space 31 via the at least one low-pressure kidney 71 to the low-pressure bore and therefore to the low-pressure reservoir is opened, whilst the first hydraulic connection to the low-pressure pre-compression space is simultaneously present. [0037] Then, in a third rotational angle position of the drive shaft 40, the second hydraulic connection alone is opened. [0038] In a fourth rotational angle position of the drive shaft 40, before the cylinder space 31 produces a hydraulic connection to the high-pressure kidney 72, a third hydraulic connection from the cylinder space 31 via the filling bore 75 and the connecting bore 22 into the pre-compression space 50, in particular the high-pressure pre-compression space, is opened. [0039] Then, in a fifth rotational angle position of the drive shaft 40, a fourth hydraulic connection from the cylinder space 31 via the at least one high-pressure kidney 72 to the high-pressure bore, and therefore to the high-pressure reservoir, is opened, whilst the third hydraulic connection to the high-pressure pre-compression space is simultaneously present. [0040] Then, in a sixth rotational angle position of the drive shaft 40, the fourth hydraulic connection from the cylinder space 31 via the at least one high-pressure kidney 72 to the high-pressure bore, and therefore to the high-pressure reservoir, alone is opened.

[0041] During operation, working fluid from the working pistons 32, which are connected on the path from an upper to a lower dead center position and to the low-pressure reservoir, is extracted via the second hydraulic connection and then moved from the lower into the upper dead center position by means of the rotation piston drum 40 and thereby compressed in the decreasing cylinder space 31 in that the sliding blocks 62 slide along a circular path of the pivot cradle 60 and thereby press the working pistons 32 into the cylinder bores 31 on their path from the lower to the upper dead center and thus decrease the cylinder spaces 31. In this region, the cylinder spaces 31 are connected to the high-pressure reservoir via the third hydraulic connection and the working fluid is therefore supplied to the high-pressure reservoir.

[0042] The critical rotational angle position is as follows:

[0043] If a cylinder space 31 which is under low pressure starts to move via the high-pressure kidney 72 owing to the rotation of the piston drum 30 and is therefore connected to the high-pressure reservoir, this results in a “sudden” virtually unthrottled filling of the cylinder space 31 with fluid under high pressure. This transmission is critical in terms of both strength and noise.

[0044] This critical rotational angle position is eased by the use of a pre-compression volume in the pre-compression space 50:

[0045] During the transition from the low-pressure region to the high-pressure region, a pre-compression space 50 is hydraulically connected such that it is connected to the cylinder space 31 via the first hydraulic connection as soon as the cylinder space 31 is no longer connected to the low-pressure reservoir via the second hydraulic connection; otherwise, there would be a “short circuit” between the low-pressure reservoir and the pre-compression space 50. In this position, the third hydraulic connection is still closed. As a result of the throttling function within the first hydraulic connection, the cylinder space 31 is placed under high pressure relatively slowly. Upon a further rotational movement of the piston drum 30, the third hydraulic connection between the cylinder space 31 and the high-pressure reservoir is opened; working fluid is pressed into the high-pressure reservoir owing to the decreasing cylinder space 31. At the same time, the first hydraulic connection is still open so that the pre-compression space 50, which is decompressed with respect to the high-pressure reservoir, is refilled.

[0046] By comparison with an arrangement outside the housing 10, the arrangement of the at least one pre-compression space 50 in the connection plate 20 presents an arrangement which saves on installation space, for example, and the NVH (Noise Vibration Harshness) behavior and the sound radiation are improved.