JP2020076411A - Hydraulic pump or hydraulic motor - Google Patents

Abstract

To suppress a machining cost for positioning a swash plate on a case.SOLUTION: A hydraulic pump/motor 1 includes a second bearing 15 fixed to a case 10, a rotating shaft 20 rotatably held on the second bearing 15, a cylinder block 30 held on the rotating shaft 20 to be rotated together with the rotating shaft 20, and having a plurality of cylinder holes 31 extending along the axial direction of the rotating shaft 20, pistons 40 slidably held in the plurality of cylinder holes 31, respectively, and a swash plate 50 arranged between the cylinder block 30 and the second bearing 15, and having a slope face 51 on the side of the cylinder block 30. The swash plate 50 is positioned in the radial direction by the second bearing 15.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydraulic pump or hydraulic motor used for construction vehicles and the like.

  Hydraulic pumps or hydraulic motors are widely used in construction vehicles and the like. A general hydraulic pump or hydraulic motor includes a bearing fixed to a case, a rotary shaft rotatably held by the bearing, and a rotary shaft held by the rotary shaft so as to rotate together with the rotary shaft. A cylinder block having a plurality of extending cylinder holes, a piston slidably held in each of the plurality of cylinder holes, and a swash plate having an inclined surface.

  In such a hydraulic pump or hydraulic motor, the swash plate is provided so that its sloping surface is inclined with respect to the surface orthogonal to the axial direction of the rotating shaft. For example, Patent Document 1 discloses a configuration in which a wall portion that is inclined with respect to a surface orthogonal to the axial direction of the rotation shaft is formed in the case, and the swash plate is fixed to the wall portion. In this structure, the slope of the swash plate extends along the wall portion, whereby the slope is inclined.

  When the swash plate is fixed to the wall of the case as described above, the swash plate is usually fixed to the wall after being positioned on the wall. Here, a structure for positioning the swash plate may be formed on the wall portion. As such a positioning structure, for example, a recessed part for fitting a swash plate and positioning the position may be adopted. Since such a positioning structure is generally formed in order to properly perform centering of the swash plate, it is usually processed precisely.

JP, 2014-208982, A

  By the way, in the configuration in which the inclined wall portion is formed in the case as in Patent Document 1 described above, the structure of the case becomes complicated, and the processing cost of the case increases. In addition to this, when the swash plate positioning structure is further formed on the wall portion, the wall portion is inclined, so that it takes a lot of time and labor for processing. Therefore, there is a problem that the processing cost of the case increases significantly.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hydraulic pump or a hydraulic motor that can reduce the processing cost for positioning the swash plate in the case.

  The present invention provides a bearing fixed to a case, a rotating shaft rotatably held by the bearing, a plurality of rotating shafts held by the rotating shaft so as to rotate together with the rotating shaft, and extending along an axial direction of the rotating shaft. A cylinder block in which a cylinder hole is formed, a piston slidably held in each of the plurality of cylinder holes, a cylinder block and a bearing, and a slope is provided on the cylinder block side. A hydraulic pump or hydraulic motor comprising: a swash plate, wherein the radial position of the swash plate is positioned by the bearing.

  According to the present invention, by utilizing the bearing for positioning the swash plate, the structure for positioning the swash plate in the case can be easily and easily formed. Thereby, the processing cost for positioning the swash plate on the case can be suppressed.

Further, the hydraulic pump or the hydraulic motor may further include a pin extending across the case and the swash plate, and the swash plate may be stopped by the pin.
According to this structure, the rotation of the swash plate with respect to the case can be reliably prevented by the pin.

Further, in the hydraulic pump or the hydraulic motor, a part of the bearing projects toward the swash plate side, and the swash plate engages with a part of the projected bearing, thereby The position in the radial direction may be positioned.
According to this structure, by engaging the swash plate with a part of the bearing, the swash plate can be easily positioned at a desired position with high accuracy in accordance with the dimensional accuracy of the bearing. That is, since the dimensional accuracy of the bearing is usually controlled with high accuracy, this configuration allows the swash plate to be accurately positioned at a desired position by engaging the swash plate with a part of the bearing. Can be easily positioned.

  According to the present invention, by utilizing the bearing for positioning the swash plate, the structure for positioning the swash plate in the case can be easily and easily formed. Thereby, the processing cost for positioning the swash plate on the case can be suppressed.

It is a sectional view of a hydraulic pump or a hydraulic motor concerning one embodiment of the present invention. It is sectional drawing which follows the AA line of FIG. It is a figure explaining the modification of the hydraulic pump or hydraulic motor shown in FIG. It is a figure explaining the other modification of the hydraulic pump or hydraulic motor shown in FIG.

  An embodiment of the present invention will be described below with reference to the drawings. The hydraulic pump or hydraulic motor 1 described below can be applied to, for example, a construction vehicle such as a hydraulic excavator, but is not limited to the construction vehicle and can be applied to devices in various fields.

  FIG. 1 is a sectional view of a hydraulic pump or hydraulic motor 1 according to an embodiment of the present invention. As shown in FIG. 1, the hydraulic pump or hydraulic motor 1 includes a case 10, a rotary shaft 20, a cylinder block 30, a piston 40, and a swash plate 50.

  The case 10 has a main case 11 formed in a tubular shape, and a sub case 12 attached to the main case 11 so as to cover an open portion on one end side of the main case 11. A partition wall 13 is formed in the main case 11 to partition the hollow region of the case in the axial direction. An internal space S for accommodating the cylinder block 30 and the swash plate 50 is formed between the partition wall portion 13 and the sub case 12.

  The first bearing 14 is inserted and fixed in a fitting hole formed in the surface of the sub case 12 on the internal space S side, and the fitting hole formed in the surface of the partition wall 13 on the internal space S side. The second bearing 15 is inserted into and fixed to. In the illustrated example, the first bearing 14 is a radial ball bearing, and has an inner race 14A, an outer race 14B, and a rolling element 14C held between the inner race 14A and the outer race 14B. Similarly, the second bearing 15 is a radial ball bearing and has an inner race 15A, an outer race 15B, and a rolling element 15C held between the inner race 15A and the outer race 15A.

  One end of the rotary shaft 20 is rotatably supported by the first bearing 14, and the intermediate part between the one end and the other end is supported by the second bearing 15. The other end of the rotary shaft 20 extends from the partition wall portion 13 so as to project to the outside (the side opposite to the internal space S side). In FIG. 1, reference numeral L1 indicates the central axis of the rotary shaft 20. In the following description of the present embodiment, the extending direction of the central axis L1 and the direction along the central axis L1 (extending in parallel) are referred to as the axial direction of the rotary shaft 20 or simply the axial direction. A direction orthogonal to the central axis L1 is called a radial direction, and a direction around the central axis L1 is called a circumferential direction.

  The cylinder block 30 is arranged on the outer side in the radial direction of the rotary shaft 20, and is held by the rotary shaft 20 so as to rotate together with the rotary shaft 20. In the illustrated example, the cylinder block 30 is held by the rotary shaft 20 by spline fitting. The cylinder block 30 is formed in a shape that extends along the entire circumference in the circumferential direction on the radially outer side of the rotating shaft 20 when viewed along the axial direction. A plurality of cylinder holes 31 extending in the axial direction are formed in the cylinder block 30. The plurality of cylinder holes 31 are arranged at intervals in the circumferential direction on the same circumference.

  The piston 40 is slidably held in each of the plurality of cylinder holes 31, and is movable back and forth along the axial direction. Each of the pistons 40 is adapted to advance to the swash plate 50 side by supplying hydraulic oil from a hydraulic pump (not shown) to the cylinder holes 31 from the sub case 12 side. Further, each of the pistons 40 is configured to retract toward the sub case 12 side by being pushed by a later-described beveled surface 51 of the swash plate 50 and discharging the hydraulic oil supplied to the cylinder holes 31. A shoe 41 is swingably attached to each end of each piston 40 on the swash plate 50 side. These shoes 41 slide on the slope 51 of the swash plate 50.

  The swash plate 50 is arranged between the cylinder block 30 and the second bearing 15. The swash plate 50 has a slope 51 on the cylinder block 30 side for rotating the piston 40 in the circumferential direction of the rotary shaft 20. Further, the swash plate 50 has a support side surface 52 formed on the second bearing 15 side in parallel with a surface orthogonal to the axial direction. The inclined surface 51 is inclined with respect to the surface orthogonal to the axial direction. The piston 40 is in contact with the slope 51 via the shoe 41. On the other hand, in the illustrated example, the support side surface 52 is in contact with the partition wall portion 13. Further, the swash plate 50 is formed with an insertion hole 53 through which the rotary shaft 20 is inserted.

  The swash plate 50 is configured to apply a reaction force along the circumferential direction to the piston 40 when the piston 40 advances to the slope 51 side. As a result, when the hydraulic oil is supplied to the cylinder hole 31 and the piston 40 advances, the piston 40 rotationally moves in the circumferential direction, and accordingly, the cylinder block 30 and the rotary shaft 20 rotate integrally. Is becoming

  In the present embodiment, the swash plate 50 is positioned in the radial direction by the second bearing 15. In the illustrated example, the swash plate 50 is in radial contact with the second bearing 15. Particularly in the illustrated example, the swash plate 50 is in direct contact with the second bearing 15. Specifically, in the example shown in FIG. 1, the end portion of the second bearing 15 on the swash plate 50 side projects from the partition wall portion 13 to the swash plate 50 side. The swash plate 50 is positioned in the radial direction by engaging with the end of the second bearing 15 on the swash plate 50 side so as to be in direct contact therewith. As described above, the swash plate 50 is positioned in the radial direction with respect to the second bearing 15, and thus is also positioned in the radial direction with respect to the case 10.

  FIG. 2 is a sectional view taken along the line AA of FIG. In FIG. 2, for convenience of description, dots are added to the swash plate 50, and the second bearing 15 is not shown in cross section. More specifically, as shown in FIGS. 1 and 2, a fitting recessed portion that extends radially outward from the insertion hole 53 and has an annular shape when viewed axially is formed in the peripheral edge portion of the insertion hole 53 in the support side surface 52 of the swash plate 50. 54 is formed. The end of the second bearing 15 on the side of the swash plate 50 is inserted into the fitting recess 54.

  In this state, the outer peripheral surface of the outer race 15B of the second bearing 15 is in contact with the inner peripheral surface of the fitting recess 54. With this configuration, the second bearing 15 positions the swash plate 50 in the radial direction. Further, by inserting the second bearing 15 into the fitting recess 54, the radial relative movement of the swash plate 50 with respect to the second bearing 15 is restricted. That is, the swash plate 50 is positioned by the second bearing 15 with respect to the second bearing 15, and is maintained in a state of being positioned with respect to the second bearing 15. Further, in the present embodiment, since the end portion of the second bearing 15 on the swash plate 50 side is inserted into the fitting recess 54, the swash plate 50 is prevented from falling off the second bearing 15. Therefore, the swash plate 50 is fixed to the second bearing 15. Thereby, a fastening member such as a bolt for fixing the swash plate 50 can be eliminated, and the number of parts can be suppressed.

  Further, as shown in FIG. 1, when the end of the second bearing 15 on the swash plate 50 side is inserted into the fitting recess 54, the support side surface 52 of the swash plate 50 contacts the partition wall portion 13. There is. This positions the swash plate 50 in the axial direction.

  Further, between the partition wall portion 13 and the swash plate 50, one or a plurality of pins 55 extending across them are provided. The pin 55 extends along the axial direction. The swash plate 50 is stopped by a pin 55. That is, the pin 55 restricts the relative movement of the swash plate 50 in the circumferential direction with respect to the case 10 and the second bearing 15. Thereby, the circumferential position of the swash plate 50 is positioned, and the swash plate 50 is maintained at the positioned position. Each of the partition wall portion 13 and the swash plate 50 has a hole into which the pin 55 is inserted.

  In the present embodiment described above, the radial position of the swash plate 50 is positioned by the second bearing 15. By using the second bearing 15 for positioning the swash plate 50 in this manner, the positioning structure for the swash plate 50 in the case 10 can be easily and easily formed. Thereby, the processing cost for positioning the swash plate 50 on the case 10 can be suppressed.

  Further, according to the present embodiment, the swash plate 50 can be downsized. That is, in this type of hydraulic pump or hydraulic motor, a brake may be provided on the outer side in the radial direction of the cylinder block. In this case, the case is formed to have a relatively large diameter, and the swash plate is fixed to the case. The wall also has a large diameter. In such a case, in a structure in which a positioning structure such as a recess is formed in the wall, since the positioning structure is generally formed over a wide area of the wall, the swash plate has a size of the wall and a size of the positioning structure. It is formed in a relatively large size. In particular, when the wall portion is inclined as in Patent Document 1 described above, the size of the swash plate becomes even larger. On the other hand, in the present embodiment, the swash plate 50 can be positioned without considering the size of the wall portion and the like, so that the swash plate 50 can be downsized.

  Further, in the present embodiment, the swash plate 50 is prevented from rotating by the pin 55 extending across the partition wall portion 13 of the case 10 and the swash plate 50. Therefore, the rotation of the swash plate 50 with respect to the case 10 can be reliably prevented by the pin 55.

  Further, in the present embodiment, the end portion on the swash plate 50 side that is a part of the second bearing 15 projects to the swash plate 50 side, and the swash plate 50 engages with the end portion, The position in the radial direction is positioned. Accordingly, the swash plate 50 can be easily and accurately positioned at a desired position according to the dimensional accuracy of the second bearing 50. That is, since the dimensional accuracy of the bearing is normally controlled with high accuracy, according to this configuration, by engaging the swash plate 50 with a part of the second bearing 15, the swash plate 50 is desired. It can be easily and accurately positioned.

  Specifically, the swash plate 50 can be easily and accurately positioned at a desired position where the swash plate 50 is centered with respect to the rotary shaft 20. Here, "the swash plate 50 is centered with respect to the rotary shaft 20" means that the piston 40 of the slope 51 of the swash plate 50 and the central axis L1 of the rotary shaft 20 slide through the shoes 41. The moving annular sliding area and the sliding area are arranged coaxially.

  More specifically, the case 10 is generally formed by casting. In this case, when forming the positioning structure for the swash plate, which is composed of a recess or the like in the wall, as in the conventional case, it is necessary to form the recess or the like by scraping the casting surface, and the swash plate can be centered. It takes a great deal of time to process the positioning structure with a certain degree of precision.

  On the other hand, according to the configuration in which the swash plate 50 is positioned by the engagement with the second bearing 15 as in the present embodiment, the swash plate 50 is positioned according to the dimensional accuracy of the second bearing 15. .. Moreover, by using the second bearing 15, compared to forming the positioning structure from the casting surface, it is possible to significantly reduce the time and labor for positioning. Therefore, the swash plate 50 can be easily and accurately positioned at a desired centering position.

  That is, the bearings 14 and 15 that support the rotating shaft 20 are arranged on the surface formed in the case 10 with high precision by cutting and subsequent polishing. As a result, the bearings 14 and 15 are accurately positioned with respect to the case 10. Moreover, the inner peripheral surface of the inner race and the outer peripheral surface of the outer race of the bearings 14 and 15 are also precisely machined into surfaces formed with high precision. In addition, since the second bearing 15 supports the rotating shaft 20, the second bearing 15 maintains a predetermined positional relationship with the rotating shaft 20, that is, a state of being coaxial with the rotating shaft 20. Therefore, the swash plate 50 is positioned in the radial direction by the second bearing 15, in particular by abutting on the outer race 15B, so that the swash plate 50 is held by the rotation shaft 20 and the rotation shaft 20. It is possible to easily and highly accurately position it at a desired position centered with respect to 30. Thus, it is possible to stably secure the expected engagement between the slope 51 of the swash plate 50 and the piston 40 of the cylinder block 30.

  Further, in the present embodiment, the swash plate 50 is provided with the fitting recess 54 for inserting the end of the second bearing 15 on the swash plate 50 side. The fitting recess 54 is required to be precisely processed so that the swash plate 50 can be properly centered. Here, since the fitting recess 54 can be processed in a state in which the swash plate 50 is separated from the case 10, it can be easily and accurately formed. Therefore, according to the configuration in which the end portion of the second bearing 15 on the swash plate 50 side is inserted and positioned in the fitting recess 54 as in the present embodiment, the centering accuracy of the swash plate 50 can be further improved. It will be possible.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. Hereinafter, a modified example of the above-described embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 and FIG. 4 are views for explaining modifications of the hydraulic pump or hydraulic motor 1 shown in FIG. 1, respectively.

  In the modification shown in FIG. 3, a projection 56 projecting toward the partition wall 13 is integrally formed with the swash plate 50 at a position radially outside the fitting recess 54 on the support side surface 52 of the swash plate 50. .. On the other hand, the partition wall portion 13 is formed with a recess 13A into which the protrusion 56 is inserted. The recess 13A communicates with a fitting hole formed in the partition wall 13 into which the second bearing 15 is press-fitted in the radial direction. The protrusions 56 projecting from the supporting side surfaces 52 of the swash plate 50 contact the outer race 15B of the second bearing 15 from the outside in the radial direction when inserted into the recess 13A, and are provided on both sides of the recess 13A in the circumferential direction. It comes in contact with the wall surface.

  In this modification, by inserting the second bearing 15 into the fitting recess 54 of the swash plate 50, the swash plate 50 is positioned in the radial direction, and at the same time, the projection 56 integral with the swash plate 50 is recessed. 13A, the swash plate 50 can be positioned in the circumferential direction.

  Further, in the modification shown in FIG. 4, the fitting recess 54 described in the embodiment is not formed on the support side surface 52 of the swash plate 50. On the other hand, on the supporting side surface 52 of the swash plate 50, a protrusion 56 similar to the modification shown in FIG. 3 is formed. The second bearing 15 inserted and held in the partition wall portion 13 does not project to the swash plate 50 side and is flush with the surface of the partition wall portion 13 on the swash plate 50 side.

  Further, the partition wall portion 13 is formed with a recess 13A into which the protrusion 56 similar to that of the modification shown in FIG. 3 is inserted. This recess 13A communicates in the radial direction with a fitting hole formed in the partition wall portion 13 into which the second bearing 15 is press-fitted, as in the above. The protrusions 56 projecting from the supporting side surfaces 52 of the swash plate 50 contact the outer race 15B of the second bearing 15 from the outside in the radial direction when inserted into the recess 13A, and are provided on both sides of the recess 13A in the circumferential direction. It comes in contact with the wall surface.

  In this modification, the swash plate 50 can be positioned in the radial direction and the circumferential direction by inserting the projection 56 integrated with the swash plate 50 into the recess 13A.

  It should be noted that various modifications can be added to the above-described embodiment in addition to the modifications described above. For example, in the above-described embodiment, an example in which the second bearing 15 is a radial ball bearing has been described, but the second bearing 15 may be a sliding bearing or the like, or a rolling element is a roller or the like. It may be.

  Further, as in the modified example shown in FIG. 4, in the configuration in which the second bearing 15 is flush with the surface of the partition wall portion 13 on the swash plate 50 side, the outer race 15B of the second bearing 15 has A protrusion that protrudes toward the plate 50 may be formed. Then, the position in the radial direction of the swash plate 50 may be positioned by engaging the protrusion protruding from the outer race 15B with the inner peripheral surface of the insertion hole 53 of the swash plate 50, for example.

1 hydraulic pump or hydraulic motor 10 case 11 main case 12 sub case 13 partition wall 13A recess 14 first bearing 14A inner race 14B outer race 14C rolling element 15 second bearing 15A inner race 15B outer race 15C rolling element 20 rotating shaft 30 cylinder block 31 cylinder hole 40 piston 41 shoe 50 swash plate 51 slope 52 support side surface 53 insertion hole 54 fitting recess 55 pin 56 protrusion L1 center axis S internal space

  The present invention provides a bearing fixed to a case, a rotating shaft rotatably held by the bearing, a plurality of rotating shafts held by the rotating shaft so as to rotate together with the rotating shaft, and extending along an axial direction of the rotating shaft. A cylinder block in which a cylinder hole is formed, a piston slidably held in each of the plurality of cylinder holes, a cylinder block and a bearing, and a slope is provided on the cylinder block side. In a hydraulic pump or a hydraulic motor including a swash plate, the swash plate has a protrusion on a surface opposite to the slope side, and the protrusion is inserted into a recess formed in the case. Provided is a hydraulic pump or a hydraulic motor, which is in contact with the bearing from the outside in the radial direction and is in contact with both side walls in the circumferential direction of the recess, and the radial position of the swash plate is positioned by the bearing. To do.

Claims (3)

A bearing fixed to the case,
A rotating shaft rotatably held by the bearing,
A cylinder block which is held by the rotary shaft so as to rotate together with the rotary shaft, and in which a plurality of cylinder holes extending in the axial direction of the rotary shaft are formed;
A piston slidably held in each of the plurality of cylinder holes,
In a hydraulic pump or hydraulic motor, which is disposed between the cylinder block and the bearing, and includes a swash plate having a slope on the cylinder block side,
A hydraulic pump or a hydraulic motor, wherein a radial position of the swash plate is positioned by the bearing. Further comprising a pin extending across the case and the swash plate,
The hydraulic pump or hydraulic motor according to claim 1, wherein the swash plate is stopped by the pin. A part of the bearing projects toward the swash plate,
The hydraulic pump or hydraulic motor according to claim 1 or 2, wherein the swash plate is positioned in the radial direction of the swash plate by engaging a part of the protruding bearing.

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