Centering the housing parts of an axial piston machine

Abstract

A hydrostatic axial piston machine is disclosed, in the housing of which a drive shaft is rotatably mounted about an axis of rotation. The housing comprises a pot-like housing part having a first abutment and a cover-like housing part having a second abutment. The two abutments are clamped against one another in a sealing manner. A first fitting pin is inserted precisely into a first fitting recess of the first abutment on the one hand and into a second fitting recess of the second abutment on the other hand. A second fitting pin is provided on a side opposite the axis of rotation, which is inserted precisely into a third fitting recess of the first abutment on the one hand and into a fourth fitting recess of the second abutment on the other hand. The second fitting recess has a radial widening relative to the axis of rotation, whereby the second fitting recess is a slotted hole and/or a fitting groove.

Claims

1. A hydrostatic axial piston machine, comprising: a housing; a drive shaft rotatably mounted in the housing about an axis of rotation, wherein the housing comprises a pot-like housing part having a first abutment and a cover-like housing part having a second abutment, and wherein the two abutments abut each other in a sealing manner; a first fitting pin inserted precisely into a first fitting recess of the first abutment on the one hand and into a second fitting recess of the second abutment on the other hand; and a second fitting pin provided on a side opposite the axis of rotation and inserted precisely into a third fitting recess of the first abutment on the one hand and into a fourth fitting recess of the second abutment on the other hand, wherein the second fitting recess has a radial widening relative to the axis of rotation, and wherein the second fitting recess is a slotted hole and/or a fitting groove.

2. The axial piston machine according to claim 1, wherein a radial extension of the second fitting recess is only a maximum of 7% greater than an extension of the second fitting recess in the circumferential direction.

3. The axial piston machine according claim 1, wherein all four fitting recesses are formed as respective blind holes.

4. The axial piston machine according to claim 1, wherein the two abutments of the two housing parts lie in a respective plane and are completely circumferential, and wherein a flat seal is arranged between the two abutments which has two through-recesses through which the two fitting pins extend.

5. The axial piston machine according to claim 4, wherein the through-recess for the first fitting pin has a radial widening relative to the axis of rotation, and wherein the through-recess is a slotted hole.

6. The axial piston machine according to claim 1, wherein the two housing parts are fastened to one another by way of a plurality of screws, and wherein the pot-like housing part has blind threaded holes for the screws.

7. The axial piston machine according to claim 1, further comprising a distribution plate having two kidney-shaped control openings clamped against the cover-like housing part, one of which is configured to act as a high-pressure kidney and the other of the two kidney-shaped control openings of which is configured as a low-pressure kidney during operation of the axial piston machine, and wherein the drive shaft is mounted in the cover-like housing part by way of a rolling bearing, and wherein the distribution plate has a central recess having an inner edge, by way of which the distribution plate is mounted on an outer ring of the rolling bearing.

8. The axial piston machine according to claim 7, wherein in an abutment region of the cover-like housing part, against which the distribution plate is clamped, at least one cast radial recess is provided, extending in the radial direction and which is further formed by the distribution plate to form a radial channel section connecting an outer circumferential region of the distribution plate and thus an interior of the housing to the outer ring of the rolling bearing.

9. The axial piston machine according to claim 8, wherein a control opening is provided in the distribution plate that is fluidically connected to the cast radial recess, and wherein a radial outer end section of a groove base of the cast radial recess has a slope in the area of the outer edge of the distribution plate.

10. The axial piston machine according to claim 8, wherein, when viewed along the axis of rotation, a cast space is provided axially adjacent to the rolling bearing on a side of the rolling bearing opposite the distribution plate in the cover-like housing part, wherein at least one cast axial recess is formed in an inner case section of the cover-like housing part, against which the outer ring of the rolling bearing abuts, extending in the axial direction, and which is further formed by the outer ring to an axial channel, connecting the radial channel section to the cast space.

11. The axial piston machine according to claim 8, wherein an alignment recess of the cover-like housing part is arranged in the cast radial recess.

12. The axial piston machine according to claim 8, wherein an alignment recess of the cover-like housing part is arranged between two arms of the cast radial recess.

13. The axial piston machine according to claim 8, wherein an alignment recess of the cover-like housing part is arranged adjacent to the cast radial recess.

14. The axial piston machine according to claim 7, further comprising an alignment pin inserted into an alignment recess of the cover-like housing part on the one hand and into an alignment recess of the distribution plate on the other hand.

15. The axial piston machine according to claim 1, wherein two work connections of the axial piston machine are formed on the cover-like housing part, and wherein a flattened section and/or recess of the cover-like housing part is formed on an outer side of the cover-like housing part between the two work connections that is set back along the axis of rotation.

16. The axial piston machine according to claim 1, wherein two work connections of the axial piston machine are formed in the cover-like housing part, and wherein a pre-compression volume is arranged in the cover-like housing part between the two work connections.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an axial piston machine in accordance with a first embodiment of the present disclosure in a longitudinal section;

(2) FIG. 2 is a perspective view of a pot-shaped housing part of the axial piston machine of FIG. 1;

(3) FIG. 3 is a perspective view of a cover-like housing part of the axial piston machine of FIG. 1 with a rolling bearing and with a distribution plate;

(4) FIG. 4 is a further perspective view of the cover-like housing part of FIG. 3 without rolling bearings and distributor plate;

(5) FIG. 5 is a perspective view of a flat seal of the axial piston machine of FIG. 1;

(6) FIG. 6 is a further perspective view of the cover-like housing part of the axial piston machine of FIG. 1;

(7) FIG. 7 is a perspective view of a deviating exemplary embodiment of the cover-like housing part;

(8) FIG. 8 is a perspective view of another example of a cover-like housing piece for the axial piston machine of FIG. 1;

(9) FIG. 9 is a perspective view of another example of a cover-like housing part for the axial piston machine of FIG. 1;

(10) FIG. 10 is a sectioned perspective view of another example of a cover-like housing piece for the axial piston machine of FIG. 1; and

(11) FIG. 11 is a sectioned view of the cover-like housing part of FIG. 10.

DETAILED DESCRIPTION

(12) Two embodiment examples of the present disclosure will be described in the following on the basis of the accompanying figures.

(13) FIG. 1 shows a hydrostatic axial piston machine in accordance with a first exemplary embodiment of the present disclosure in a longitudinal section. The axial piston machine may operate as a pump and as a motor, wherein its stroke volume is adjustable by way of a pivotable swashplate 1. For this purpose, an adjustment device 2 is provided, by way of which the swashplate 1 can be pivoted against the force of a return spring or an extension spring 3 in the direction of increasing swivel angle and thus increasing stroke volume. A plurality of pistons 4 are distributed around the circumference of a cylinder drum 5 and arranged approximately parallel to a drive shaft 6 and coupled to the swashplate 1. The drive shaft 6 is rotationally fixedly connected to the cylinder drum 5, but the cylinder drum 5 is axially displaceable from the drive shaft 6. The cylinder drum 5 is clamped by way of a compression spring 8 (in FIG. 1 to the right) such that respective circumferential cylinder openings 10 are pressed against a stationary distribution plate 12.

(14) FIG. 3 shows the circular disk-shaped distribution plate 12 with the two kidney-shaped control openings, wherein the control opening permanently provided for the high pressure is stabilized with three webs, resulting in four partial openings, while the control opening provided for the low-pressure is continuous.

(15) Referring back to FIG. 1, it can be seen that the axial piston machine comprises a two-piece housing composed of a pot-like housing part 14 (in FIG. 1 on the left) and a cover-like housing part 16 (in FIG. 1 on the right). The drive shaft 6 is mounted with a rolling bearing 18 configured as a tapered roller bearing in the cover-like housing part 16 and with a further tapered roller bearing in the pot-like housing part 14.

(16) FIG. 2 shows a perspective view of the pot-shaped housing part 14 of the axial piston machine of FIG. 1. It can be seen that this housing part 14 has a circumferential flat first abutment 20 in which four blind threaded holes for screws (not shown) are formed, with which this housing part 14 is clamped against the cover-like housing part 16 in a sealing manner. Furthermore, a first fitting recess 21 and a third fitting recess 23, which are also configured as blind holes, are arranged in areas of the first abutment 20 diametrically opposite the axis of rotation 7. In the two fitting recesses, a fitting pin 31, 32 is inserted.

(17) FIG. 3 shows a perspective view of the cover-like housing part 16 of the axial piston machine of FIG. 1. It can be seen that this housing part 16 also has a circumferential flat second abutment 26 in which four through-holes for the screws (not shown) are formed, with which this housing part 16 is clamped against the pot-like housing part 14 in a sealing manner. Furthermore, a second fitting recess 22 and a fourth fitting recess 24, which are also configured as blind holes, are arranged in areas of the second abutment 26 diametrically opposite the axis of rotation 7. In the two fitting recesses 22, 24, one of each of the fitting pins 31, 32 is inserted (shown in FIG. 2).

(18) In the exemplary embodiment shown, the two fitting pins 31, 32 are circular cylindrical and can therefore also be referred to as cylindrical pins. The first and third and fourth fitting recesses 21, 23, 24 are also circular cylindrical and a precise fit. The second fitting recess 22, on the other hand, has a radial widening relative to the axis of rotation 7, while it has no widening around the axis of rotation 7 in the circumferential direction. The second fitting recess 22 is therefore a slotted hole and/or a fitting groove. However, as the widening is so small that the radial extension is less than 107% of the extension in the circumferential direction, the widening is hardly visible in the illustration of FIG. 3. This prevents stresses of the two housing parts 14, 16 when they are assembled and screws together.

(19) Looking at FIG. 2, an advantageous enlargement of the main housing opening and a deviation from the circular shape of the main housing opening of the pot-like housing part 14 is realized compared to the prior art.

(20) With reference to FIG. 3 again, the roller bearings 18 for the drive shaft 6 (see FIG. 1), which is inserted in the cover-like housing part 16 and the distribution plate 12 abutting the cover-like housing part 16 are shown. The stationary distribution plate 12 is centered over the stationary outer ring of the rolling bearing 18. The correct rotational position of the distribution plate 12 is ensured by an alignment pin 34, which is inserted into an alignment recess 35 of the cover-like housing part 16 on the one hand and into an alignment recess 36 of the distribution plate 12 on the other hand. The alignment recess 36 of the distribution plate 12 is arranged directly adjacent to the outer edge 12c of the distribution plate 12 and extends in the radial direction up to that outer edge 12c.

(21) In the distribution plate 12 in the circumferential direction of the cylinder drum 5 just before the low-pressure kidney, a control opening 12a, which is configured as the control bore, is provided and explained in more detail with reference to FIGS. 11 and 12.

(22) FIG. 4 shows a further perspective view of the cover-like housing part 16 of FIG. 3, but without the distributor plate 12 and without the rolling bearing 18. An inner case section 38 for the outer ring of the rolling bearing 18 and the abutment area 39 for the distribution plate 12 can thus be seen.

(23) When viewed along the axis of rotation 7, axially adjacent to the rolling bearing 18, a cast space 48 is formed in the cover-like housing part 16, into which an end section of the drive shaft 6 extends. The space 48 is connected to the interior of the housing by two channels opposite to one another relative to the axis of rotation 7 so that a pressure equalization can take place here. The outer ring of the rolling bearing 18 therefore does not impede the pressure equalization with the space 48.

(24) For this pressure equalization, two trough-shaped cast recesses 44 are provided in the abutment area 39 for the distribution plate 12, which extend in a radial direction. These recesses 44 are each further formed by the distribution plate 12 into a radial channel section connecting the outer circumferential area of the distribution plate 12 and thus an interior of the housing with the outer ring of the rolling bearing 18.

(25) Two trough-shaped cast axial recesses 38 are formed in the inner case section 38 of the cover-line housing part 16, against which the outer ring of the rolling bearing 18 abuts, only one of which can be seen in FIG. 4. These recesses 38 extend approximately parallel to the axis of rotation 7 and are each further formed by the outer ring of the rolling bearing 18 into an axial channel section. Finally, two further cast trough-shaped recesses 47 or radial channel sections are provided, only one of which can be seen in FIG. 4, and which then eventually open into the cast space 48.

(26) In the exemplary embodiment shown, the alignment recess 35 for the alignment pin 34 is arranged in one of the two first-mentioned trough-shaped recesses 44. In this case, the relevant trough-shaped recess 44 is widened radially on the outside in the area of the alignment pin 34 in a circumferential direction relative to the radially inner transverse dimensions such that the alignment pin 34 is surrounded by the trough-shaped recess 44 over its entire circumference.

(27) FIG. 5 shows a flat seal 50 of the axial piston machine of FIG. 1, which is clamped between the two housing parts 14, 16, more specifically between their two abutments 20, 26. The flat seal 50 has two through-recesses 41, 42 through which the two fitting pins 31, 32 extend.

(28) The second through-recess 42 of the flat seal 50 through which the second fitting pin 32 extends is in the form of a slotted hole, and corresponds to the form of the slotted hole of the second fitting recess 22. This ensures that the first fitting pin 31, even if it is in one of its extreme positions due to tolerances or manufacturing inaccuracies, does not impair the correct position and thus the function of the flat seal 50.

(29) A breakthrough 52 of the flat seal 50 seals a fluid channel from the high-pressure connection A to the adjustment device 2 on the pot-shaped housing part 14.

(30) The flat seal 50 thus has two functions: sealing the housing and sealing the channel (control oil bore) to report the high pressure.

(31) FIG. 6 shows an outside perspective view of the cover-like housing part 16 from FIGS. 1, 3 and 4. The two work connections A, B of the axial piston machine are formed on opposite sides of the cover-like housing part 16.

(32) An outer flattened section 54 of the cover-like housing part 16 is formed between the two work connections A, B, which is set back along the axis of rotation 7. This serves to save materials.

(33) The flattened section 54 extends transversely to the axis of rotation 7 up to the edge of the cover-like housing part 16 and up to the work connections A, B. In this way, the cover-like housing part 16 has the required stiffness, wherein in particular the maximum deflection of the housing part 16 under load is small, such that the flat seal 50 (see FIG. 5) seals properly.

(34) FIG. 7 shows a perspective outside view of a deviating exemplary embodiment of the cover-like housing part 116, in which a pre-compression volume 118 is arranged between the two work connections A, B. The pre-compression volume 118 is configured as a substantially circular cylindrical blind hole, the central axis of which crosses the axis of rotation 7 perpendicularly, wherein the two work connections A, B face perpendicularly away from the central axis. The blind hole is pre-cast and drilled by machining. The open side of the blind hole is sealed with a closing screw with sealing ring (not shown) in a fluid-tight manner.

(35) Within the cover-like housing part 116, a (not visible) channel in the form of a straight bore is provided, which connects the pre-compression volume 118 to the distribution plate 12. A small bore is provided in the distribution plate 12 in the circumferential direction between the two kidney-shaped control openings, such that a cylinder of the cylinder drum 5 is fluidically connected to the pre-compression volume 118 via its cylinder opening 10 (see FIG. 1) when it is positioned or moved between the kidney-shaped control openings.

(36) FIG. 8 shows a cover-like housing part 216, which can be attached to the pot-like housing piece 14 of the axial piston machine of FIG. 1 instead of the cover-like housing piece 16. A different design of the two radial recesses 244 opposite one another relative to the axis of rotation 7 (not shown in FIG. 8) is shown. The two radial recesses 244 are not widened at their outer end sections in the circumferential direction, but are divided in two. The two radial recesses 244 each have an approximately y-shaped design with consistent cross-sections. More specifically, in the exemplary embodiment shown, the two recesses 244 each have a radially inner rectilinear section and a radial outer arcuate section.

(37) The alignment recess 35 for the alignment pin 34 (shown in FIG. 1) is arranged between the two end sections of the radial outer arcuate section of the one (left in FIG. 8) radial recess 244.

(38) FIG. 9 shows a cover-like housing part 316, which can be attached to the pot-like housing piece 14 of the axial piston machine of FIG. 1 instead of the cover-like housing piece 16. A different design of the two cast radial recesses 344 opposite one another relative to the axis of rotation 7 is shown. The two radial recesses 344 are angled. Each radial recess 344 has a radially aligned inner section and an inclined outer end section. The two inclined outer end sections are both inclined towards the high-pressure kidney.

(39) The alignment recess 35 for the alignment pin 34 (shown in FIG. 1) is arranged adjacent to the end section of the one radial recess 344 (shown in FIG. 9).

(40) In both cover-like housing parts 216; 316 of FIGS. 8 and 9, the radial recess 244; 344 (shown on the right in each case) is extended in a stepped manner up to the cast space 48, such that it is also pressure-equalized with the (other) interior of the housing. To this end, a cast axial recess 246; 346 is provided, which together with the outer ring of the rolling bearing 18 forms an axial channel.

(41) With both cover-like housing parts 216; 316 of FIGS. 8 and 9, a mechanical reinforcement of the cover-like housing part 216; 316 results.

(42) FIG. 10 is a sectioned perspective view of a further exemplary embodiment of a cover-like housing part 416 with further components of the axial piston machine of FIG. 1.

(43) In the distribution plate 12 in the circumferential direction of the cylinder drum 5 just before the low-pressure kidney, the control bore 12a shown in FIG. 3 is provided, which is fluidically connected to the cast radial recess 444. This fluidic connection is realized via a comparatively short control groove 12b running in the circumferential direction, which is formed in the side of the distribution plate 12 abutting the abutment area 39 of the cover-like housing part 416. Only one end section of this control groove 12b with a small cross-section is shown in FIG. 10. This results in a relief flow path from a cylinder pressurized with a high pressure via its opening 10 provided in the cylinder drum 5 through the control bore 12a along the control groove 12b and via the radial cast groove or recess 444 towards the interior of the housing. This relief flow path is advantageous when the axial piston machine is operating as a pump with a minimum swing angle to compensate only for leakage of a circuit with a hydraulic consumer that is under load.

(44) In accordance with the disclosure, the radial cast groove or recess 444 is largely comparable to the radial cast recess 344 of FIG. 9. In contrast to the recess 344 of FIG. 9, a slope 445 is formed at the radial outer end section of the groove bae of the recess 444 in the area of the outer circumferential area of the distribution plate 12, of which only one (radial outer) part can be seen in FIG. 10. This slope 445 may also be referred to as a guide surface or a guide ramp for the pressure means and is cast together with the cover-like housing part 416. Due to the slope 445, the pressure means, which in the case of oil is also referred to as the control oil, and which flows via this relief flow path, is deflected away from the flat seal 450 according to the arrow and directed against the inner wall of the pot-like housing part.

(45) FIG. 11 is a sectioned view of the cover-like housing part 416 of FIG. 10. It is contemplated that the slope 445 extends at its radial inner (end) section to below the outer edge 12c of the distribution plate 12. Thus, when considering the direction of flow of the pressure means from radially inwards to radially outwards, the slope 445 starts further radially inwards than the outer edge 12c of the distribution plate 12. In other words, the deflection of the pressure means already begins below the outer edge 12c of the distribution plate 12.

(46) If space is available, the start of the slope 445 may alternatively be arranged outside of the outer edge 12c of the distribution plate 12 in order to reduce the cross-section of the cast groove only after the outer edge 12c of the distribution plate 12 in order to thereby avoid constriction of the relief flow path. As the start of the slope 445 outside the outer edge 12c is already in the interior of the housing, the constriction has less negative influence in this regard than when the slope 445 already starts within the outer edge 12c. In the case of a compact design of the interior of the housing, it is possible that the slope 445 must then be steeper.

(47) The depressurized pressure means (control oil) may not now come into direct contact with the flat seal 450, which would place it under adverse stress. There are also dirt particles or metal particles (due to cavitation erosion) in the depressurized pressure medium (control oil), which are therefore also not thrown directly onto the flat gasket 450. This prevents the flat seal 450 from leaking. This reduces risk to people and the environment.

LIST OF REFERENCE NUMBERS

(48) 1 Swashplate 2 Adjustment device 3 Extension spring 4 Piston 5 Cylinder drum 6 Drive shaft 7 Axis of rotation 8 Compression spring 9 Cylinder opening 12 Distribution plate 12a Control opening/Control bore 12b Control groove 12c Outer edge 14 Pot-like housing part 16 Cover-like housing part 18 Rolling bearing 20 First abutment 21 First fitting recess 22 Second fitting recess (slotted hole) 23 Third fitting recess 24 Fourth fitting recess 26 Second abutment 31 First fitting pin 32 Second fitting pin 34 Alignment pin 35 Alignment recess 36 Alignment recess 38 Inner case section 41 Through-recess for the first fitting pin (slotted hole) 42 Through-recess for the second fitting pin 44 Cast radial recess 46 Cast axial recess 47 Further cast radial recess 48 Cast space 50 Flat seal 52 Breakthrough 54 Flattened section 116 Cover-like housing part 118 Pre-compression volume 216 Cover-like housing part 244 Cast radial recess 246 Cast axial recess 316 Cover-like housing part 344 Cast radial recess 346 Cast axial recess 416 Cover-like housing part 444 Cast radial recess 445 Slope 450 Flat seal A Work connection/High-pressure connection B Work connection/Low-pressure connection