Axial piston machine with pressure relief in the through drive space

Abstract

A swashplate-type axial piston machine includes a housing, a first pivot bearing received in the housing, a drive shaft rotatably mounted in respect of an axis of rotation, a cylinder drum, a control plate, a third control aperture in the plate, and a first channel arranged in the housing. The first pivot bearing delimits a first and second housing space from one another. The drum and the plate are arranged in the first housing space. The plate has at least a first and at least a second control aperture. The first aperture is in fluidic exchange connection with a first fluid connection on the housing. The second aperture is in fluidic exchange connection with a second fluid connection on the housing. The third aperture is arranged in the peripheral direction between a first and a second aperture. The first channel fluidically connects the third aperture to the second housing space.

Claims

1. A swashplate axial piston machine, comprising: a housing; a first pivot bearing arranged in the housing, the first pivot bearing and the housing defining a first housing space and a second housing space that are on opposite sides of the first pivot bearing from each other; a drive shaft rotatably mounted in the first pivot bearing in respect of an axis of rotation; a cylinder drum arranged in the first housing space, the cylinder drum surrounding the drive shaft and in rotary drive connection with the drive shaft; a control plate arranged in the first housing space and arranged in a direction of the axis of rotation between the cylinder drum and the housing, the control plate having at least one first control aperture and at least one second control aperture, the at least one first control aperture in fluidic exchange connection with a first fluid connection on the housing, and the at least one second control aperture in fluidic exchange connection with a second fluid connection on the housing; a third control aperture in the control plate arranged in a peripheral direction between the at least one first control aperture and the at least one second control aperture; a first channel defined in the housing and fluidically connecting the third control aperture to the second housing space.

2. The axial piston machine according to claim 1, wherein a cross-sectional area of the first channel increases constantly from the third control aperture to the second housing space.

3. The axial piston machine according to claim 1, wherein the third control aperture includes a constant circular cross-sectional shape.

4. The axial piston machine according to claim 1, wherein: the third control aperture and the first channel are directly adjacent; and a transitional region cross-sectional area of the first channel in a corresponding transitional region that is directly adjacent to the third control aperture is larger than a third control aperture cross-sectional area of the third control aperture.

5. The axial piston machine according to claim 1, wherein the first channel includes a straight or curved, kink-free profile.

6. The axial piston machine according to claim 1, further comprising: a second channel defined by the housing, the second channel fluidically connecting the first housing space to the second housing space.

7. The axial piston machine according to claim 6, wherein a smallest cross-sectional area of the second channel is larger than a largest cross-sectional area of the first channel.

8. The axial piston machine according to claim 6, wherein the second channel includes an outlet opening arranged adjacent to an outer circumferential surface of the control plate.

9. The axial piston machine according to claim 6, wherein: the housing further defines a protruding portion of the second housing space; and the second channel opens out into the protrusion.

10. The axial piston machine according to claim 6, wherein the first channel and the second channel are configured such that, when the axial piston machine is operating, a higher pressure prevails in the second housing space than in the first housing space.

11. The axial piston machine according to claim 1, wherein a portion of the drive shaft is arranged in the second housing space.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosure is explained in greater detail below with the help of the attached drawings. In the drawings:

(2) FIG. 1 shows a longitudinal section of an axial piston machine according to the disclosure;

(3) FIG. 2 shows a sectional view of the second housing part with control plate of the axial piston machine according to FIG. 1;

(4) FIG. 3 shows a perspective view of the entire arrangement according to FIG. 2 from the control plate; and

(5) FIG. 4 shows the view according to FIG. 3, but without the control plate.

DETAILED DESCRIPTION

(6) FIG. 1 shows a longitudinal section through an axial piston machine 10 according to the disclosure, wherein the sectional plane runs through the axis of rotation 13. The axial piston machine 10 has a housing 20 which is made up of a first and a second housing part 25, 26. The first housing part 25 has a pot-like design, wherein it defines the first housing space 21. The second housing part 26 has a connection-plate-type design, wherein it has a first and a second fluid connection 11; 12. The second housing part 26 defines a second housing space 22, wherein it delimits the first housing space 21 along with the first housing part 25. A first pivot bearing 51 which is received in the second housing part 26 is arranged between the first and second housing space 21; 22. A second pivot bearing 52 is moreover received in the first housing part 25. A drive shaft 50 is rotatably mounted in respect of an axis of rotation 13 in the first and in the second pivot bearing 51; 52. The drive shaft 50 projects with a drive pin 53 from the housing 20, wherein it projects with a through-drive pin 54 into the second housing space 22. The drive pin and through-drive pin 53; 54 may be provided with a multi-spline profile, for example. The first and the second pivot bearings 51; 52 may be configured as a tapered roller bearing, for example. The through-drive pin 54 may be used to drive a further hydraulic machine, wherein the wall portion of the housing 20 labelled no. 24 is drilled for this purpose.

(7) Between the first and the second pivot bearing 51; 52 the drive shaft 50 is surrounded by a cylinder drum 60 which is in rotary drive connection with the drive shaft 50 in the present case via a multi-spline profile. A control plate 80 is fitted between the cylinder drum 60 and the second housing part 26. In the pressureless state, the cylinder drum 60 is pressed by the spring 64 against the control plate 80 and the second housing part 26, so that they bear against one another in a gapless manner. If the axial piston machine 10 is under pressure, a hydraulic contact force moreover takes effect.

(8) The cylinder drum 60 is provided with multiple cylinder bores 61 which are uniformly distributed about the axis of rotation 13. An associated piston 62 is received in each cylinder bore 61 in a linearly movable manner. The corresponding movement direction may be parallel or slightly inclined relative to the axis of rotation 13. The pistons 62 project out of the cylinder drum 60 with one end, wherein they are each provided with a tiltable slide shoe 63 there via a ball joint. The slide shoe 63 slides on a planar drive surface 72 which is arranged on a separate pivot cradle 70 in the present case, wherein it may also be fixedly arranged on the housing 20, in particular on the first housing part 25. The pivot cradle 70 is tiltably mounted in two pivot bearings 73 in respect of a pivot axis 71. The pivot axis 71 is arranged perpendicularly to the axis of rotation 13, wherein it intersects said axis of rotation or is arranged at a small distance therefrom. The pivot bearings 73 in the present case are configured as slide bearings, wherein an anti-friction bearing-mounted pivot cradle can also be used. By pivoting the pivot cradle 70, the drive surface 72 can be moved into a position in which it adopts an angle that differs by 90° C. in respect of the axis of rotation 13.

(9) The pistons 62 with the slide shoes 63 bear against the working surface 72 when the axial piston machine 10 is under pressure. Accordingly, they perform a lifting movement when the cylinder drum 60 turns. So that the lifting movement takes place even when the axial piston machine 10 is pressureless, the retraction plate 65 is provided which rests against a pressure ring 66 via a ball surface, wherein the pressure ring 66 is in turn supported by the drive shaft 50.

(10) Reference should also be made to the leakage oil connection 23 on the first housing part 25 which is closed using a locking screw in the present case. The leakage oil connection 23 is preferably attached to a tank during operation. It should further be recognized how the first fluid connection 11, in particular, is fluidically connected to the control plate 80, wherein reference is made to the embodiments in FIG. 4 for further details.

(11) FIG. 2 shows a sectional view of the second housing part 26 with the control plate 80 of the axial piston machine according to FIG. 1. The corresponding sectional plane runs through the first and the second channel 41; 42 in the second housing part 26. The control plate 80 is configured as a planar plate with a constant thickness, which is preferably made of brass. Radially inwardly it bears against the outer ring of the first pivot bearing 51, so that it is secured to prevent displacement transversely to the axis of rotation. The control plate 80 has a first 81, a second (no. 82 in FIG. 4) and a third control aperture 83. The third control aperture 83 is configured as a circular-cylindrical bore which passes through the control plate 80 in the direction of the axis of rotation. If a cylinder bore is above the third control aperture 83, pressure fluid which is contained under pressure can be relieved via the third control aperture 83, further via the first channel 41 to the second housing space 22. The aforementioned flow path in this case runs largely along a straight line, so that virtually no cavitation phenomena occur. The length and diameter of the first channel 41 in this case are designed in such a manner that the pressure along the first channel drops constantly in a friction-induced manner. The diameter of the third control aperture 83 is smaller than the constant diameter of the first channel 41. In this way it is ensured in each tolerance position that the third control aperture 83 is not covered by the second housing part 26. Instead, it opens out with its entire outlet opening into the first channel 41. The first channel 41 has a straight design, wherein it runs in an inclined manner to the axis of rotation in such a manner that it opens into the second housing space 22.

(12) The pressure in the tank or an only slightly higher pressure compared with the pressure in the tank prevails in the second housing space 26. In order to achieve this, the second channel 41 is provided in the present case. This runs with a constant circular cross-sectional shape along a straight line. In this case, it is tilted in respect of the axis of rotation in such a manner that it opens out into a protrusion 44 of the second housing space 22. The diameter of the second channel 42 is substantially larger than that of the first channel 41. Accordingly, there is substantially no pressure drop along the second channel 42. In order to minimize the installation space, the outlet opening 43 of the second channel 42 to the first housing space 21 is arranged in such a manner that it is partially covered by the control plate 80. The remaining free opening outlet 43 is so large that there is no excessively great pressure drop. The outlet opening 43 is arranged in the region of an outer peripheral surface 84 of the control plate 80.

(13) FIG. 3 shows a perspective view of the overall arrangement according to FIG. 2 from the control plate 80. The first, second and third control apertures 81; 82; 83 which are arranged along a circle, the center point whereof is defined by the axis of rotation, can be identified in particular. The single first control aperture 81 in this case is kidney-shaped, wherein it extends with a constant width along the aforementioned circle. In this way, a particularly large open cross-sectional area is produced. A total of six second control apertures 82 are arranged along the aforementioned circle in this case. These are circular in design, wherein the circular cross section thereof is slightly smaller than the width of the first control aperture 81. The high pressure of the axial piston machine is applied in the region of the second control apertures 82, wherein the many separate second control apertures 82 exhibit a greater pressure resistance than a single kidney-shaped control aperture.

(14) The third control aperture 83 which has already been explained is arranged in the peripheral direction between the first control aperture 81 and a second control aperture 82, the diameter whereof is substantially smaller than the width of the first control aperture 81 or the diameter of the second control apertures 82. The direction of rotation of the cylinder drum is preferably selected in such a manner that the cylinder bores come into fluidic exchange connection with the third control aperture 83 when they move from the second control apertures 82 to the first control aperture 81. Accordingly, the pressure fluid constrained under high pressure in the respective cylinder bore is relieved via the third control aperture 83 to the second housing space 22.

(15) Furthermore, the alignment recess 85 on the outer peripheral surface 84 of the control plate 80 is still to be referred to. A cylinder pen which is fitted in an associated bore (no. 86 in FIG. 4) engages with said recess. In this way, the control plate 80 is secured relative to the second housing part 26 to prevent rotation.

(16) FIG. 4 shows the view according to FIG. 3 but without the control plate. A first outlet opening 27 which is fluidically connected to the first fluid connection 11 is arranged in the second housing part 26. The form of the first outlet opening 27 is substantially in alignment with the first control aperture on the control plate. A common second outlet opening 28 in the second housing parts 26 is assigned to all second control apertures, which outlet opening is fluidically connected to the second fluid connection 12. The second outlet opening 28 is kidney-shaped, wherein it runs with a constant width along a circle, the center point whereof is defined by the axis of rotation. The aforementioned width is substantially identical to the diameter of the second control apertures.

(17) Furthermore, the outlet opening of the first channel 41 which is arranged in the peripheral direction between the first and the second outlet opening 27; 28 can be seen in FIG. 4.

LIST OF REFERENCE NUMERALS

(18) 10 Axial piston machine

(19) 11 First fluid connection

(20) 12 Second fluid connection

(21) 13 Axis of rotation

(22) 20 Housing

(23) 21 First housing space

(24) 22 Second housing space

(25) 23 Leakage oil connection

(26) 24 Wall portion for through drive

(27) 25 First housing part (pot-like)

(28) 26 Second housing part (connection plate)

(29) 27 First outlet opening

(30) 28 Second outlet opening

(31) 41 First channel

(32) 42 Second channel

(33) 43 Outlet opening of the second channel

(34) 44 Protrusion

(35) 50 Drive shaft

(36) 51 First pivot bearing

(37) 52 Second pivot bearing

(38) 53 Drive pin

(39) 54 Through-drive pin

(40) 60 Cylinder drum

(41) 61 Cylinder bore

(42) 62 Piston

(43) 63 Slide shoe

(44) 64 Spring

(45) 65 Retraction plate

(46) 66 Pressure ring

(47) 70 Pivot cradle

(48) 71 Pivot axis

(49) 72 Drive surface

(50) 73 Pivot bearing

(51) 80 Control plate

(52) 81 First control aperture

(53) 82 Second control aperture

(54) 83 Third control aperture

(55) 84 Outer peripheral surface

(56) 85 Alignment recess

(57) 86 Bore for alignment pin