JPH0730939Y2 - Axial piston pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an improvement of an axial piston pump used as a drive source of a hydraulic circuit of an industrial machine or the like.

[Prior Art] As a conventional axial piston pump (hereinafter, simply referred to as a pump), the one shown in FIG. 5 is known. This pump has a drive shaft via bearings 51a and 52a in a sealed space 50 formed by a casing 51 and an end cover 52.
A cylinder block 55 having a plurality of bores 54 is fitted to a spline 531 of the drive shaft 53 so as to be displaceable in the axial direction. In addition, the casing 51 has a swash plate 56.
Is swingably supported, and each bore 54 of the cylinder block 55 is
Inside is a piston 57 via a shoe 67 moored to a swash plate 56.
Is stored so that it can reciprocate. An intake port that communicates with the bore 54 between the cylinder block 55 and the end cover 52.
The valve plate 58 with the 581 and the discharge port 582 is the end cover 52.
The portion of the valve plate 58 excluding the suction port 581 and the discharge port 582 seals the bore opening ends 541 and 542 of the cylinder block 55. The end cover 52 is formed with a suction port 521 and a discharge port 522 which communicate with the suction port 581 and the discharge port 582, respectively. Further, a compression spring 63 is arranged in the annular space 60 between the drive shaft 53 and the cylinder block 55 via spacers 61 and 62, and one spacer 61 is pin 64 by the urging force of the compression spring 63. The pivot 65 is pressed via the, and the pivot 65 is loosely fitted to the shoe retainer 66 fitted to the shoe 67. The other spacer 62 presses the cylinder block 55 in the direction opposite to the pivot 65 via the circlip 68 by the biasing force of the compression spring 63. This pump is equipped with a variable capacity mechanism 69 symmetrically with respect to the drive shaft 53, and the displacement angle is changed by changing the tilt angle of the swash plate 56 by the operation of the variable capacity mechanism 69. .

In such a pump, the rotation of the drive shaft 53 causes the spline 53 to rotate.
The cylinder block 55 rotates via 1 and the piston 57 reciprocates in the bore 54 of the cylinder block 55 in accordance with the inclination angle of the swash plate 56, thereby causing a change in volume of the bore 54 and reducing the operating pressure of the low pressure hydraulic oil. Is sucked from the suction port 521 through the suction port 581 into the bore 54 in the middle of increasing the volume, and high-pressure hydraulic oil is discharged from the bore 54 in the middle of decreasing the volume at the discharge port 522 through the discharge port 582. In this pump, leaked oil flowing out from the high-pressure open end 542 or the like escapes into the closed space 50, and is used to lubricate sliding parts such as the swash plate 56 and the shoe 67 in the closed space 50. . The excess oil in the closed space 50 is discharged from the drain hole 59 at appropriate times.

[Problems to be solved by the invention] However, in the above pump, the compression spring 63 urges the pivot 65 through the pin 64 and the like, and the hydraulic oil in the high pressure state inside the bore 54 passes through the shoe 67. The force to the left in the figure, which is the reaction force exerted on the retainer 66, and the swash plate 56
The force acting in the right direction in the figure by the reaction acting on the shoe retainer 66 via 67 causes the pivot 65 and the shoe retainer 66 to receive a pressing force at their loosely fitted surfaces 65a.
The pressing force is such that high-pressure hydraulic oil is discharged from the discharge port 582.
The pulsation is generated at the moment when the liquid is discharged from the two, acting on both of them, and a swinging sliding contact is generated on the loose fitting surface 65a of both. Although both rotate in synchronization with the rotation of the drive shaft 53, the pivot 65 is fitted to the drive shaft 53 by the spline 531 while the shoe retainer 66 is a shoe for reciprocating the piston 57. Since it is loosely fitted to the inclined swash plate 56 via 67,
Swing-sliding contact still occurs on the loose fitting surfaces 65a of both.
Further, the rotational sliding contact around the loose fitting surface 65a for suction and discharge for each half rotation accompanying the rotation of the drive shaft 53 is also repeated. Therefore, in the loose fitting surface 65a, due to the pressing force repeatedly applied during the operation of the pump, the sliding contact, etc., despite the existence of leaked oil in the closed space 50, the temperature rises due to heat generation and poor lubrication. In some cases, seizure may occur. Particularly, in the variable displacement pump shown in FIG. 5, the displacement angle is changed frequently by changing the inclination angle of the swash plate 56 by the operation of the variable displacement mechanism 69. If the tilt angle of the swash plate 56 is changed, the pivot 65 and the shoe retainer 66 repeatedly swing and slide on the free fitting surface 65a within the tilt angle range, and seizure is more likely to occur.

The present invention has been devised in view of the above circumstances, and it is a technical problem to be solved to effectively prevent seizure on a loosely fitted surface between a pivot and a shoe retainer in a variable displacement pump. Is.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the pump of the present invention has at least one of the pivot and the shoe retainer from the maximum inclination angle to the minimum inclination angle of the swash plate on the loose fitting surface of both. A new means is adopted by engraving an oil groove at a position where a part of the oil can appear and disappear in the enclosed space within the range.

It is desirable that the oil groove be formed in one line in the circumferential direction.

[Operation] In the pump of the present invention, the oil groove is formed on at least one of the pivot and the shoe retainer, so that the leaked oil in the sealed space is supplied into the oil groove, and the two are pressed against each other and slidably contact each other. Even if the above is repeated, it is suitably lubricated.

Particularly, in the pump according to the first aspect, the oil groove is formed at a position where a part of the swash plate on the loosely fitting surface of the pivot and the shoe retainer can appear and disappear in the sealed space within a range from the maximum tilt angle to the maximum tilt angle. Since it is provided, when the swash plate is at the minimum inclination angle, it is possible to prepare for the subsequent inclination of the swash plate by supplying the leaked oil into the oil groove. Also, when the swash plate is at the maximum inclination angle, the maximum pressing force due to the maximum reaction force acts on the pivot and shoe retainer, but even under the maximum pressing force, the leaked oil will surely leak into the oil groove in sequence. Supplied.

Further, in the pump according to the second aspect, it is only necessary to engrave one oil groove in the circumferential direction, and it is relatively easy to engrave the oil groove.

Embodiments Embodiments embodying the present invention will be described below with reference to the drawings.

As shown in FIG. 1, this pump has a bearing in a closed space 10 formed by a casing 11 and an end cover 12.
A drive shaft 13 is supported via 11a and 12a. A cylinder block 15 is fitted to the drive shaft 13 by a spline 131 so as to be displaceable in the axial direction, and a swash plate 16 is pivotally supported on the casing 11 by a pivot shaft (not shown) so that it can only swing. A plurality of bores 14 are formed in the cylinder block 15 so as to extend concentrically with the drive shaft 13 in the axial direction, and a piston 17 reciprocates in each bore 14 while being moored to a swash plate 16 via shoes 27. It is stored as much as possible. Between the cylinder block 15 and the end cover 12, a valve plate 18 having an arc-shaped suction port 181 and a discharge port 182 at a position corresponding to the rotation trajectory of the piston 17 is fixed to the end cover 12. Portions of the valve plate 18 excluding the suction port 181 and the discharge port 182 seal the bore opening ends 141 and 142 of the cylinder block 15. Further, the end cover 12 has a suction port 121 and a discharge port communicating with the suction port 181 and the discharge port 182, respectively.
122 is formed.

An annular space 20 is formed between the drive shaft 13 and the cylinder block 15, and a spacer 21, in the annular space 20,
A compression spring 23 is arranged via 22. One of the spacers 21 presses the pivot 25 toward the swash plate 16 side via the pin 24 by the urging force of the compression spring 23, and the shoe retainer 26 loosely fitted to the pivot 25 is rotatably engaged with the piston 17. It is fitted with the shoe 27. The other spacer 22 presses the cylinder block 15 toward the valve plate 18 side by a biasing force of the compression spring 23 via a circlip 28 that fits the spacer 22 itself to the cylinder block 15.

As a characteristic configuration of the present embodiment, the pivot 25 is provided with an oil groove 41 on a loosely fitting surface 25a with which the shoe retainer 26 is fitted. As shown in FIG. 2, the oil groove 41 is formed in one line in the circumferential direction, and its position is on the swash plate 16 side.

Further, as shown in FIG. 1, this pump is of a variable capacity type. That is, the end cover 12 has a guide tube 31
An urging rod 33 that engages with the swash plate 16 is slidably inserted into the guide cylinder 31 via a spring 32. On the other hand, the support cylinder is located at the axially symmetrical position of the end cover 12.
34 is fixed, an operating body 36 that engages with the swash plate 16 is also provided outside the support cylinder 34, and a restriction rod 37 that restricts the movement range of the operating body 36 is inserted inside the support cylinder 34. There is. Further, a control valve 35 for supplying hydraulic oil is fixed between the support cylinder 34 and the operating body 36 on the outer surface of the end cover 12.
In this way, the operating body 36 moves with respect to the support cylinder 34 by the balance between the pressure of the hydraulic oil supplied by the control valve 35 and the urging force of the spring 32, and determines the inclination angle of the swash plate 16. The discharge amount can be changed accordingly.

In this pump configured as described above, the rotation of the drive shaft 13 causes the cylinder block 15 to rotate via the spline 131, and the piston 17 reciprocates in the bore 14 of the cylinder block 15 via the swash plate 16. This causes a change in volume of the bore 14, sucks low-pressure hydraulic oil from the suction port 121 into the bore 14 in the process of expanding the volume through the suction port 181, and discharges high-pressure hydraulic oil from the bore 14 in the process of reducing the volume to the discharge port. It is discharged from the discharge port 122 via 182. A part of the hydraulic oil leaking from the high-pressure side bore opening end 142 and the like escapes into the closed space 10 and is used as lubricating oil for lubricating the swash plate 16 and the shoe 27. Then, the surplus oil is discharged from the drain hole 19 in a timely manner.

During such an operation, the pivot 25 and the shoe retainer 26 are constantly subjected to a pressing force on the free fitting surfaces 25a of the pivot 25 and the shoe retainer 26, and the swing sliding contact caused by the pulsation and the swing sliding contact corresponding to the tilt angle of the swash plate 16 are made. Has occurred. However, in the pump of this embodiment, the pivot
Since the oil groove 41 is engraved in 25, the leaked oil in the closed space 10 swirled and agitated by the rotation of the shoe 27 or the like is supplied into the oil groove 41, and they are pressed against each other and are in sliding contact. Even if it repeats, both are suitably lubricated. Also, the swash plate
When 16 is at the maximum inclination angle θ °, the reaction force of the hydraulic oil in the bore 14 becomes maximum, and the pivot 25 and the shoe retainer are
The maximum pressing force acts on the loosely fitted surface 25a with respect to 26.
However, in the pump of the present embodiment, even in such a case, the leaked oil is sequentially and reliably supplied into the oil groove 41, and the both are appropriately lubricated. The engraving of the oil groove 41 can be performed relatively easily, and the processing cost does not increase.

Although the oil groove 41 is formed in the circumferential direction of the pivot 25 in the above embodiment, as in the modification shown in FIGS. 3 and 4,
It is also possible to engrave the oil groove 42 in the radial direction on the free fitting surface 25a of the pivot 25. In this case, since the oil groove 42 is not always closed by the shoe retainer 26 regardless of the inclination angle of the swash plate 16, both can be favorably lubricated at any inclination angle.

Further, in the above-described embodiment and modification, the pivot 25 has an oil groove 41,
Although 42 is engraved, it is also effective to engrave an oil groove in the shoe retainer 26.

[Advantages of the Invention] As described in detail above, in the axial piston pump of the first and second aspects, since the specific oil groove is formed on the free fitting surface of the pivot and the shoe retainer, both of them can be formed on the free fitting surface. The image sticking can be effectively prevented. Therefore, the life of the axial piston pump can be extended.

Further, in the axial piston pump of the second aspect, it is relatively easy to engrave the oil groove in one line in the circumferential direction, so that the processing cost can be reduced.

[Brief description of drawings]

1 to 4 relate to an embodiment of the present invention, FIG. 1 is a sectional view of an axial piston pump, FIG. 2 is a sectional view of essential parts, and FIG.
FIG. 4 and FIG. 4 are cross-sectional views of main parts of another embodiment. FIG. 5 is a sectional view of a conventional axial piston pump. 10 ... Sealed space, 11 ... Casing 12 ... End cover, 13 ... Drive shaft 14 ... Bore, 15 ... Cylinder block 141, 142 ... Bore opening end 16 ... Swash plate, 17 ... Piston 18 ... Valve plate, 181 ... Suction port 182 … Discharge port, 20… Annular space 23… Compression spring, 25… Pivot 25a… Free fitting surface, 26… Shoe retainers 41, 42… Oil groove

Claims (2)

[Scope of utility model registration request] 1. A drive shaft supported in a closed space formed by a casing and an end cover, and a cylinder having a plurality of bores, which rotates together with the drive shaft and is urged toward the end cover by a compression spring. The block, a pivot that is biased in the opposite direction to the cylinder block by the compression spring and is loosely fitted to the shoe retainer, a swash plate pivotably supported by the casing, and the shoe retainer are fitted together. A plurality of pistons moored to the swash plate via shoes and reciprocating in each of the bores; and a valve plate having suction and discharge ports communicating with the bores and closing the bore opening end of the cylinder block. In an axial piston pump including, at least one of the pivot and the shoe retainer has a range from a maximum inclination angle to a minimum inclination angle of the swash plate on a loosely fitting surface of both. An axial piston pump, wherein an oil groove is engraved at a position where a part of the oil groove can appear in and out of the closed space. 2. The axial piston pump according to claim 1, wherein the oil groove is formed in one line in the circumferential direction.