JP6878635B2 - Hydraulic pump or hydraulic motor - Google Patents

Description

The present invention relates to a hydraulic pump or a hydraulic motor used in a construction vehicle or the like.

Hydraulic pumps or hydraulic motors are often used in construction vehicles and the like. A general hydraulic pump or hydraulic motor has a bearing fixed to a case, a rotating shaft rotatably held by the bearing, and a rotating shaft held by the rotating shaft so as to rotate with the rotating shaft, along the axial direction of the rotating shaft. It has a cylinder block in which a plurality of cylinder holes extending by the shaft are formed, a piston slidably held in each of the plurality of cylinder holes, and a sloping plate having a slope.

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

When the swash plate is fixed to the wall portion of the case as described above, the swash plate is usually fixed to the wall portion after being positioned on the wall portion. Here, a structure for positioning the swash plate may be formed on the wall portion. As such a positioning structure, for example, a recess in which a swash plate is fitted to position the position can be adopted. Such a positioning structure is generally formed in order to properly center the swash plate, and is therefore usually precisely machined.

Japanese Unexamined Patent Publication No. 2014-208982

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

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a hydraulic pump or a hydraulic motor capable of suppressing the processing cost for positioning a swash plate on a case.

The present invention includes a bearing fixed to a case, a rotary shaft rotatably held by the bearing, and a plurality of rotary shafts held by the rotary shaft so as to rotate together with the rotary shaft and extend along the axial direction of the rotary shaft. The cylinder block in which the cylinder holes are formed, the piston slidably held in each of the plurality of cylinder holes, and the cylinder block and the bearing are arranged between the cylinder block and the bearing, and have a slope on the cylinder block side. In a hydraulic pump or hydraulic motor provided with 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 the wall surfaces on both sides of the concave portion in the circumferential direction, and the position of the swash plate in the radial direction is positioned by the bearing. To do.

According to the present invention, by using the bearing for positioning the swash plate, the positioning structure of the swash plate in the case can be easily and easily formed. As a result, 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 straddling between the case and the swash plate, and the swash plate may be stopped by the pin.
According to this configuration, 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 protruding bearing to form the swash plate. The position in the radial direction may be positioned.
According to this configuration, 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 according to the dimensional accuracy of the bearing. That is, since the dimensional accuracy of a bearing is usually controlled with high accuracy, according to this configuration, by engaging a swash plate with a part of the bearing, the swash plate can be placed at a desired position with high accuracy. Easy to position.

According to the present invention, by using the bearing for positioning the swash plate, the positioning structure of the swash plate in the case can be easily and easily formed. As a result, the processing cost for positioning the swash plate on the case can be suppressed.

It is sectional drawing of the hydraulic pump or the hydraulic motor which concerns on one Embodiment of this invention. It is sectional drawing which follows the AA line of FIG. It is a figure explaining the modification of the hydraulic pump or the hydraulic motor shown in FIG. It is a figure explaining another modification of the hydraulic pump or the hydraulic motor shown in FIG. 1.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The hydraulic pump or hydraulic motor 1 described below can be applied to 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 cross-sectional view of a hydraulic pump or a 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 rotating 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. The main case 11 is formed with a partition wall portion 13 that partitions the hollow region of the case in the axial direction. An internal space S in which the cylinder block 30 and the swash plate 50 are housed is formed between the partition wall portion 13 and the sub case 12.

The first bearing 14 is inserted and fixed in the fitting hole formed on the surface of the sub-case 12 on the internal space S side, and the fitting hole formed on the surface of the partition wall portion 13 on the internal space S side. The second bearing 15 is inserted and fixed to the space. 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 rotating shaft 20 is rotatably supported by the first bearing 14, and the intermediate portion between the one end and the other end is supported by the second bearing 15. The other end of the rotating shaft 20 extends from the partition wall portion 13 to the outside (the side opposite to the internal space S side). In FIG. 1, reference numeral L1 indicates the central axis of the rotating shaft 20. Hereinafter, in the description of the present embodiment, the extending direction of the central axis L1 and the direction along the central axis L1 (extending in parallel) will be referred to as the axial direction of the rotating shaft 20 or simply the axial direction. Further, the direction orthogonal to the central axis L1 is referred to as a radial direction, and the direction around the central axis L1 is referred to as a circumferential direction.

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

The piston 40 is slidably held in each of the plurality of cylinder holes 31 and can move forward and backward along the axial direction. Each of the pistons 40 advances to the swash plate 50 side by supplying hydraulic oil from a hydraulic pump (not shown) to the cylinder hole 31 from the sub-case 12 side. Further, each of the pistons 40 is pushed back to the sub-case 12 side by being pushed by the slope 51 described later of the swash plate 50 and discharging the hydraulic oil supplied to the cylinder hole 31. A shoe 41 is swingably attached to each of the ends 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 rotationally moving the piston 40 in the circumferential direction of the rotation shaft 20. Further, the swash plate 50 has a support side surface 52 formed parallel to a surface orthogonal to the axial direction on the second bearing 15 side. The slope 51 is inclined with respect to a plane 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 rotating shaft 20 is passed.

When the piston 40 advances to the slope 51 side, the swash plate 50 applies a reaction force along the circumferential direction to the piston 40. As a result, when the hydraulic oil is supplied to the cylinder hole 31 and the piston 40 advances, the piston 40 rotates and moves in the circumferential direction, and the cylinder block 30 and the rotating shaft 20 rotate integrally with the piston 40. It has become.

In the present embodiment, the position of the swash plate 50 in the radial direction is positioned by the second bearing 15. In the illustrated example, the swash plate 50 is in radial contact with the second bearing 15. In particular, 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 protrudes from the partition wall portion 13 toward the swash plate 50 side. The position of the swash plate 50 is positioned in the radial direction by engaging the second bearing 15 so as to be in direct contact with the end portion of the second bearing 15 on the swash plate 50 side. By positioning the swash plate 50 in the radial direction with respect to the second bearing 15 in this way, the swash plate 50 is also positioned in the radial direction with respect to the case 10.

FIG. 2 is a cross-sectional view taken along the line AA of FIG. In FIG. 2, dots are added to the swash plate 50 for convenience of explanation, and the second bearing 15 is not shown in cross section. More specifically, as shown in FIGS. 1 and 2, a fitting recess that extends radially outward from the insertion hole 53 and exhibits an annular shape in the axial direction in the peripheral portion of the insertion hole 53 on the support side surface 52 of the swash plate 50. 54 is formed. The end of the second bearing 15 on the swash plate 50 side 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 position of the swash plate 50 in the radial direction is positioned by the second bearing 15. Further, by inserting the second bearing 15 into the fitting recess 54, the relative movement of the swash plate 50 with respect to the second bearing 15 in the radial direction is restricted. That is, the swash plate 50 is positioned with respect to the second bearing 15 by 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 from the second bearing 15. Therefore, the swash plate 50 is fixed to the second bearing 15. As a result, it is possible to eliminate the need for fastening members such as bolts for fixing the swash plate 50, and it is possible to reduce the number of parts.

Further, as shown in FIG. 1, when the end portion 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 is in contact with the partition wall portion 13. There is. As a result, the position of the swash plate 50 in the axial direction is positioned.

Further, one or a plurality of pins 55 extending straddling the partition wall portion 13 and the swash plate 50 are provided. The pin 55 extends along the axial direction. The swash plate 50 is stopped around by a pin 55. That is, the pin 55 regulates the swash plate 50 from moving relative to the case 10 and the second bearing 15 in the circumferential direction. As a result, the position of the swash plate 50 in the circumferential direction is positioned, and the swash plate 50 is maintained at the positioned position. A hole into which the pin 55 is inserted is formed in each of the partition wall portion 13 and the swash plate 50.

In the present embodiment described above, the position of the swash plate 50 in the radial direction is positioned by the second bearing 15. By using the second bearing 15 for positioning the swash plate 50 in this way, the positioning structure of the swash plate 50 in the case 10 can be easily and easily formed. As a result, 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 miniaturized. That is, in this type of hydraulic pump or hydraulic motor, a brake may be provided on the radial outer side of the cylinder block, in which case the case is formed to have a relatively large diameter and the swash plate is fixed along with the case. The wall part also has a large diameter. In such a case, in a configuration in which a positioning structure such as a recess is formed in the wall portion, the positioning structure is generally formed over a wide range of the wall portion, so that the swash plate is the size of the wall portion and the size of the positioning structure. It is formed to be relatively large according to the 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 miniaturized.

Further, in the present embodiment, the swash plate 50 is stopped by a pin 55 extending straddling between the partition wall portion 13 and the swash plate 50 in the case 10. 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, which is a part of the second bearing 15, protrudes toward the swash plate 50 side, and the swash plate 50 engages with the end portion. The position in the radial direction is positioned. As a result, the swash plate 50 can be easily positioned at a desired position with high accuracy according to the dimensional accuracy of the second bearing 50. That is, since the dimensional accuracy of the bearing is usually controlled with high accuracy, according to this configuration, the swash plate 50 is desired by engaging the swash plate 50 with a part of the second bearing 15. It can be easily positioned with high accuracy.

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 rotating shaft 20. Here, "the swash plate 50 is centered with respect to the rotary shaft 20" means that the central axis L1 of the rotary shaft 20 and the piston 40 of the slope 51 of the swash plate 50 slide through the shoe 41. It means that the moving annular sliding region and the moving annular sliding region are arranged coaxially.

More specifically, the case 10 is generally formed by casting. In this case, when forming the positioning structure of the swash plate having recesses or the like on the wall portion as in the conventional case, it is necessary to form the recesses or the like by scraping the casting surface or the like, and the swash plate can be centered. It takes a lot of time and effort 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 engaging 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, it is possible to significantly reduce the labor for positioning as compared with the case where the positioning structure is formed from the casting surface. Therefore, the swash plate 50 can be easily and accurately positioned at a desired position to be centered.

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

Further, in the present embodiment, a fitting recess 54 for inserting the end portion of the second bearing 15 on the swash plate 50 side is formed in the swash plate 50. The fitting recess 54 is required to be precisely machined so that the swash plate 50 can be properly centered. Here, since the fitting recess 54 can be processed in a state where the swash plate 50 is separated from the case 10, it can be easily formed with high accuracy. Therefore, according to the configuration in which the end portion of the second bearing 15 on the swash plate 50 side is inserted into the fitting recess 54 and positioned 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-described embodiment. Hereinafter, a modified example of the above-described embodiment will be described with reference to FIGS. 3 and 4. 3 and 4 are diagrams for explaining a modified example of the hydraulic pump or the hydraulic motor 1 shown in FIG. 1, respectively.

In the modified example shown in FIG. 3, a protrusion 56 protruding toward the partition wall portion 13 is integrally formed with the swash plate 50 at a position on the laterally outer side of 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 the fitting hole formed in the partition wall portion 13 into which the second bearing 15 is press-fitted in the radial direction. When the protrusion 56 protruding from the support side surface 52 of the swash plate 50 is inserted into the recess 13A, the protrusion 56 abuts on the outer race 15B of the second bearing 15 from the outside in the radial direction, and both sides of the recess 13A in the circumferential direction. It is designed to come into 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 protrusion 56 integrated with the swash plate 50 is recessed. By inserting it into 13A, the swash plate 50 can be positioned in the circumferential direction.

Further, in the modified example 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, a protrusion 56 similar to the modified example shown in FIG. 3 is formed on the support side surface 52 of the swash plate 50. Further, the second bearing 15 inserted and held in the partition wall portion 13 does not protrude toward the swash plate 50 side, and is flush with the surface of the partition wall portion 13 on the swash plate 50 side.

Then, the partition wall portion 13 is formed with a recess 13A into which the protrusion 56 similar to the modified example shown in FIG. 3 is inserted. The recess 13A communicates in the radial direction with the fitting hole formed in the partition wall portion 13 into which the second bearing 15 is press-fitted, as described above. When the protrusion 56 protruding from the support side surface 52 of the swash plate 50 is inserted into the recess 13A, the protrusion 56 abuts on the outer race 15B of the second bearing 15 from the outside in the radial direction, and both sides of the recess 13A in the circumferential direction. It is designed to come into 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 protrusion 56 integrated with the swash plate 50 into the recess 13A.

In addition to the modifications described above, various modifications can be added to the above-described embodiment. For example, in the above-described embodiment, the example in which the second bearing 15 is a radial ball bearing has been described, but the second bearing 15 may be a slide bearing or the like, or a bearing or the like in which the rolling element is a roller. There 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 is oblique. A protrusion protruding toward the plate 50 side may be formed. Then, the position of the swash plate 50 in the radial direction may be positioned by engaging the inner peripheral surface of the swash plate 50, for example, the insertion hole 53, with the protrusion protruding from the outer race 15B.

1 Hydraulic pump or hydraulic motor 10 Case 11 Main case 12 Sub case 13 Partition wall 13A Recess 14 1st bearing 14A Inner race 14B Outer race 14C Rolling element 15 2nd bearing 15A Inner race 15B Outer race 15C Rolling body 20 Rotating shaft 30 Cylinder block 31 Cylinder hole 40 Piston 41 Shoe 50 Slanted plate 51 Slope 52 Support side surface 53 Insertion hole 54 Fitting recess 55 Pin 56 Protrusion L1 Central axis S Internal space

Claims (3)

Bearings fixed to the case and
A rotating shaft rotatably held by the bearing and
A cylinder block formed by a plurality of cylinder holes held by the rotating shaft so as to rotate together with the rotating shaft and extending along the axial direction of the rotating shaft.
A piston slidably held in each of the plurality of cylinder holes,
In a hydraulic pump or a hydraulic motor provided between the cylinder block and the bearing and provided with a swash plate having a slope on the cylinder block side.
The swash plate has a protrusion on a surface opposite to the slope side.
The protrusion is inserted into a recess formed in the case and contacts the bearing from the outside in the radial direction and also contacts the wall surfaces on both sides of the recess in the circumferential direction, and the position of the swash plate in the radial direction is positioned by the bearing. The hydraulic pump or hydraulic motor is characterized by being. Further provided with a pin extending straddling between the case and the swash plate.
The hydraulic pump or hydraulic motor according to claim 1, wherein the swash plate is detented by the pins. A fitting hole is formed in the wall portion formed in the case, and the bearing is inserted into the fitting hole.
A part of the bearing protrudes from the wall portion toward the swash plate side.
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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