JP2002147343A - Axial piston machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the constitution capable of dispensing with a cylindrical bush for fitting an inner peripheral surface and an outer peripheral surface of a thrust plate, and causing no drift of the thrust plate at rotating time in swash plates of an axial piston machine. SOLUTION: In this axial piston machine for adjacently arranging the thrust plate 2 having an outside surface 2a abutting to the tip of a piston 11 energized by a spring 10, and a rolling body 3 abutting to an inside surface 2b of the thrust plate 2 on the inside of the swash plates 12 and 15, the inside surface 2b of the thrust plate 2 is formed as a conical surface, and is constituted so that the rolling body 3 rolls along the conical surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial piston machine, and more particularly, to an axial piston machine in which a piston head is brought into contact.

[0002]

2. Description of the Related Art Hitherto, it has been widely known that an axial piston machine uses a thrust bearing at a portion where the head of the piston comes into contact.

For example, in Japanese Utility Model Publication No. Sho 60-116082, a conventional structure in which a spherical recess is provided in a shoe arranged on an inclined surface and a spherically shaped piston head is fitted into the shoe has a complicated structure and is difficult to manufacture. He points out that it takes time. In the publication, as means for solving this problem, an annular bearing, a thrust bearing (rolling element), and an annular thrust plate are sequentially arranged, and a bearing guide has a peripheral wall portion extending in the axial direction. A bottom wall extending radially from an end of the peripheral wall is provided, a thrust bearing is interposed between the bottom wall and the thrust plate, and a peripheral side of the thrust plate faces a peripheral wall of the bearing guide. It proposes a configuration to arrange.

[0004] Furthermore, the same applicant as the present application has a real fairness 7
Japanese Patent Publication No. 40-6992,
In the technique of No. 082, it is pointed out that galling or seizure occurs in a sliding portion between the outer peripheral side surface of the thrust plate and the inner peripheral surface of the swash plate base portion. A configuration has been proposed in which an annular bearing guide and an annular bearing bush are fitted in a double state inside the inner surface of the peripheral wall.

[0005]

However, the above-mentioned actual fairness 7
According to the technology of -40692, an extra cylindrical bush is required, which increases the manufacturing cost by that much,
Extra work was required for assembly. In the above configuration,
If the cylindrical bush is not fitted accurately to the inner surface of the peripheral wall of the swash plate base part, and if the outer peripheral surface of the thrust plate is not fitted accurately to the inner surface of the bush, play will occur when the axial piston machine is driven, and noise will be reduced. This not only causes the piston head but also causes wear on the piston head. Therefore, in order to avoid such a problem, it is necessary to manufacture a cylindrical bush or the like with high accuracy, which also leads to an increase in manufacturing cost.

[0006]

The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

That is, in the first aspect, the thrust plate having the outer surface with which the tip of the piston biased by the spring abuts and the rolling element abutting on the inner surface of the thrust plate are arranged adjacent to each other inside the swash plate. In the axial piston machine, the inner surface of the thrust plate is formed in a conical surface, and the rolling elements roll along the conical surface.

According to a second aspect of the present invention, the thrust plate having an outer surface with which the tip of the piston biased by the spring abuts, and a rolling element abutting on the inner surface of the thrust plate,
In an axial piston machine disposed adjacently inside a swash plate, the inner surface of the thrust plate is formed into a spherical surface, and the rolling elements roll along the spherical surface.

[0009]

Next, embodiments of the present invention will be described. FIG. 1 is a sectional view of an axial piston machine according to a first embodiment of the present invention, and FIG. 2 is an enlarged sectional view showing a configuration of a swash plate.

The configuration of the first embodiment will be described with reference to FIG. Reference numeral 50 shown in FIG. 1 is a hydraulic type continuously variable transmission, which has a configuration in which an axial piston type hydraulic pump 51 and a hydraulic motor 52 to which the present invention is applied are fluidly connected. The hydraulic pump 51 and the hydraulic motor 52 are arranged side by side on the flat center section 4, and are covered by a common housing 5.

The hydraulic pump 51 will be described. Valve plates 6 and 7 are arranged and fixed on one side (the surface facing the inside of the housing 5) of one side of the center section 4, and a cylinder block 8 of a hydraulic pump 51 is rotatably slidably mounted on one of the valve plates 6. You. A pump shaft 9 is rotatably supported by the center section 4, and a spline portion 9 a is formed in a middle portion of the pump shaft 9 so that the cylinder block 8 is formed.
Are arranged so that the cylinder block 8 rotates integrally with the pump shaft 9. A plurality of cylinder holes 8a are formed in the cylinder block 8 in parallel with the pump shaft 9, and a biasing spring 10 is disposed in each of the cylinder holes 8a. Is fitted. The piston 11 is urged in the projecting direction by the urging spring 10, and its head is in contact with the thrust plate 2 of the movable swash plate 12. The swash plate 12 is configured so that the inclination angle thereof can be changed as appropriate, and holds the thrust plate 2 rotatably. Thrust plate 2
The piston 11 which makes the head contact with the cylinder reciprocates according to the rotation of the cylinder block 8 to discharge the pressure oil, and its stroke is defined by the inclination angle of the swash plate 12. With this configuration, the discharge amount and the discharge direction of the hydraulic pump 51 can be changed by artificially changing the inclination angle of the swash plate 12.

The hydraulic motor 52 will be described. A cylinder block 8 of a hydraulic motor 52 is rotatably slidably provided on the valve plate 7. A motor shaft 14 is rotatably supported by the center section 4, and a spline portion 14 a is formed in a middle portion of the motor shaft 14, and a center hole of the cylinder block 8 is engaged with the motor shaft 14. The configuration is such that the cylinder block 8 rotates.
A plurality of cylinder holes 8a are bored in the cylinder block 8 in parallel with the axis thereof. A biasing spring 10 is disposed in each of the cylinder holes 8a, and a piston 11 is fitted to be reciprocally slidable. ing. The piston 11 is urged in the projecting direction by the urging spring 10, and its head is in contact with the thrust plate 2 of the fixed swash plate 15. With the above configuration, the pressure oil discharged from the hydraulic pump 51 is pressure-fed to the hydraulic motor 52 via an oil passage (not shown) formed in the center section 4 to make the piston 11 of the cylinder block 8 protrude. The swash plate 15 converts the driving force in the projecting direction of the piston 11 into the rotational driving force of the cylinder block 8 by the swash plate cam action, and the motor shaft 14 is driven.

In the above configuration, the configuration of each swash plate 12, 15 will be described in detail. Hydraulic pump 51
The movable swash plate 12 is formed in a so-called trunnion type.
Pivotally supported on the side wall of the vehicle, and can be tilted freely. A recess 12a is formed on the side of the swash plate 12 facing the head of the piston 11, and a thrust bearing 16 is fitted inside the recess 12a. The thrust bearing 16 is provided with a first bearing ring 1 fitted and installed on the inner bottom surface of the concave portion 12a, and a second bearing ring disposed so that the axis of the first bearing ring 1 is coincident with the first bearing ring 1 and functioning as the thrust plate. It comprises a bearing ring 2 and a conical roller 3 as a rolling element interposed between the first bearing ring 1 and the second bearing ring 2. As shown in FIG. 2 which is an enlarged view, the second raceway (thrust plate) 2 has an outer surface 2a formed in a planar shape and brought into contact with the head of the piston 11, and an inner surface 2b
Is formed on a conical surface having one point P on the axis as a vertex,
The conical roller 3 is configured to roll on a conical surface.

Here, in this embodiment, the second race (thrust plate) 2 has an inner surface 2b in contact with the conical roller 3 and an outer surface 2a in contact with the head of the piston 11. , So as not to contact other members. In other words, the present embodiment does not employ a configuration in which any stop member is brought into contact (fitting) with the outer peripheral surface or the inner peripheral surface of the thrust plate 2 in order to prevent the radial displacement of the thrust plate 2. ,
When no force is applied from the piston 11, the thrust plate 2 is configured to be able to move freely in the radial direction. However, when the hydraulic pump 51 is actually driven, the thrust plate 2 is
The piston 11 rotates while receiving the force from the piston 11. Further, the inner surface 2b of the thrust plate 2 is formed in a conical shape having a point P on the axis of the first bearing ring 1 as a vertex, and the first bearing ring 1 disposed opposite to the inner surface 2b is formed. Since the surface 1a is also formed in a conical shape and the conical roller 3 is interposed between the two conical surfaces 1a and 2b, when the thrust plate 2 rotates as described above, the thrust plate 2 rotates. Works to make the rotation axis of the thrust plate 2 coincide with the axis of the first bearing ring 1 (alignment action). Therefore, the axial center position of the thrust plate 2 is always automatically adjusted to an accurate predetermined position as the thrust plate 2 rotates, so that a situation in which the thrust plate 2 fluctuates in the radial direction when the thrust plate 2 rotates can be prevented. That is, conventionally, a special configuration such as fitting a cylindrical bush to the outer periphery of the thrust plate 2 has been adopted in order to prevent radial flapping when the thrust plate 2 rotates. In the embodiment, such a special configuration can be made unnecessary, and in this respect, it is possible to contribute to a reduction in manufacturing cost and assembly man-hour.

On the other hand, the swash plate 15 of the hydraulic motor 52 is formed as a fixed swash plate which is fitted on the inner wall surface of the housing 5 and whose inclination angle cannot be changed. A swash plate 15 is formed integrally with the housing 5 by forming a slanted concave portion 15a on the inner wall of the housing 5 opposed thereto and fitting a thrust bearing 16 into the concave portion 15a. This thrust bearing 16 is, like the swash plate 12 of the hydraulic pump 51, fitted with the first bearing ring 1 on the inner bottom surface of the recess 15a,
A second bearing ring 2 which is disposed so as to coincide with the axis of the first bearing ring 1 and functions as the thrust plate; and is interposed between the first bearing ring 1 and the second bearing ring 2. It comprises a conical roller 3 as a rolling element. The second raceway (thrust plate) 2 has its outer surface 2a in contact with the head of the piston 11, and the inner surface 2b is formed as a conical surface having the point Q on the axis as the apex. It is configured to roll on a conical surface. As a result, the thrust plate 2 that rotates with the piston 11 when the hydraulic motor 52 is driven always has an aligning action, and the thrust plate 2 is positioned so that its rotation axis coincides with the axis of the first race 1. There is no radial fluctuation during rotation.

Next, a second embodiment will be described. FIG. 3 is a sectional view of an axial piston machine according to the second embodiment. In the hydraulic stepless transmission of the second embodiment, the swash plate 12 of each of the hydraulic pump 51 and the hydraulic motor 52
At 15, an inner surface 2'b of the second bearing ring (thrust plate) 2 'of each of the thrust bearings 16 is formed in a spherical shape, and a surface of the first bearing ring 1' facing the inner surface 2'b. 1′a is formed into a conical surface, and both sides 2′b
A ball 3 'as a rolling element is interposed between 1'a. That is, the inner surface 2'b of the thrust plate 2 '
Is formed into a spherical surface instead of the conical surface of the first embodiment, and the ball 3 'is configured to roll on the spherical surface. Reference numeral 17 denotes a holding member for holding the ball 3 'so as not to fall off the spherical surface and come off. Other configurations are completely the same as those of the first embodiment. Also in this configuration, as in the first embodiment, the thrust plate 2 ′ rotates together with the swash plates 12 and 15 while receiving the extension force of the piston 11, so that the thrust plate 2 ′ has its rotating shaft. An aligning action occurs that attempts to align the center with the axis of the first race 1 '. Accordingly, the axial center position of the thrust plate 2 'is automatically adjusted to an accurate position with the rotation thereof, and a situation in which the thrust plate 2' rotates while fluttering in the radial direction is prevented.

Although the two embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the above-described embodiments, and the technical scope of the present invention will be clear from the matters described in the present specification and drawings. The invention extends widely to the full range of technical ideas that are truly intended.

[0018]

The present invention is configured as described above.
The following effects are obtained.

That is, as set forth in claim 1, a thrust plate having an outer surface with which the tip of a piston biased by a spring abuts and a rolling element abutting on the inner surface of the thrust plate are arranged adjacent to each other inside the swash plate. In the axial piston machine described above, the inner surface of the thrust plate is formed in a conical surface, and the rolling element rolls along the conical surface. Is prevented from fluttering in the radial direction, so that a configuration such as a cylindrical bush for fitting the outer peripheral surface of the thrust plate is not required, which can contribute to a reduction in manufacturing cost and assembly man-hours.

According to a second aspect of the present invention, a thrust plate having an outer surface with which the tip of a piston biased by a spring abuts, and a rolling element abutting on an inner surface of the thrust plate,
In an axial piston machine arranged adjacent to the inside of the swash plate, the inner surface of the thrust plate is formed into a spherical surface, and the rolling element rolls along the spherical surface. Since the thrust plate is prevented from fluttering in the radial direction by the centering action, a configuration such as a cylindrical bush for fitting the outer peripheral surface of the thrust plate is not required, which can contribute to a reduction in manufacturing costs and assembly man-hours.

[Brief description of the drawings]

FIG. 1 is a sectional view of an axial piston machine according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a configuration of a swash plate.

FIG. 3 is a sectional view of an axial piston machine according to a second embodiment.

[Explanation of symbols]

 2.2 thrust plate 2a / 2'a outer surface 2b / 2'b inner surface 3 conical roller (rolling element) 3 'ball (rolling element) 10 biasing spring (spring) 11 piston 51 hydraulic pump (axial piston machine) 52 Hydraulic motor (axial piston machine)

Continued on the front page F term (reference) 3H070 AA01 BB04 BB06 BB25 CC01 CC07 CC31 CC32 DD12 DD35 DD44 3H071 AA03 BB01 CC21 CC26 CC34 DD46 3H084 AA08 AA16 BB01 BB09 BB23 BB24 CC33

Claims (2)

[Claims] An axial piston machine in which a thrust plate having an outer surface with which the tip of a piston biased by a spring abuts and a rolling element abutting on an inner surface of the thrust plate are arranged adjacently inside the swash plate.
An axial piston machine, wherein the inner surface of the thrust plate is formed in a conical surface, and the rolling elements roll along the conical surface. 2. An axial piston machine in which a thrust plate having an outer surface with which the tip of a piston biased by a spring abuts and a rolling element abutting on an inner surface of the thrust plate are arranged adjacently inside the swash plate.
An axial piston machine, wherein the inner surface of the thrust plate is formed as a spherical surface, and the rolling elements roll along the spherical surface.