JPH03237271A - Cam plate type fluid pump motor - Google Patents

Abstract

PURPOSE:To simplify structure and reduce cost by forming a continuous groove of arcuate cross section at the slant face of a cam plate, as well as forming a spherical recession at the tip of each piston, and interposing balls, partially inserted into the groove and spherical recession, between the cam plate and each piston. CONSTITUTION:A cam plate 8 provided with a slant face, inclined at a fixed angle A in relation to an axis, at one end face is fixed at a fixed casing 2 in such a way as to be coaxial to a shaft 5 rotatably supported at the fixed casing 2 through bearings 3, 4. A cylinder 12 provided with plural cylinder chambers 13 in the peripheral direction is fixed at the shaft 5, and each piston 14 slidably inserted into each cylinder chamber 13 is reciprocated along the inclination of the slant face 9, in association with the rotation of the cylinder 12. In this case, the slant face 9 is provided with a continuous elliptic groove 31 of arcuate cross section extended along the outer edge of the cam plate 8, as well as a semi-spherical recession 32 is formed at the tip face of the piston 14, and plural balls 33 are interposed between the groove 31 and recession 32 to guide the sliding motion of the piston 14.

Description

[Detailed description of the invention] TECHNICAL FIELD This invention relates to swash plate fluid pump motors.

Traditionally, swash plate type fluid pumps and motors include, for example, a swash plate having a slope inclined at a constant angle with respect to the axis, a cylinder rotating around an axis coaxial with the swash plate, and a cylinder. A piston that is slidably inserted into a plurality of cylinder chambers formed in the piston and has a ball portion at the other end, and a plurality of shoes that are swingably supported by the ball portions of the piston and slidably contact the slope. things are known.

However, this type of device has a problem in that the structure becomes complicated because a shoe must be interposed between the swash plate and the piston. Moreover, if the manufacturing and assembly precision of these shoes is low, smooth sliding contact between the ball or slope and the shoe will not be possible.
The slope and the ball must be of high precision, resulting in a problem that they are expensive.

An object of the present invention is to provide a swash plate type fluid pump/motor that has a simple structure and is inexpensive.

The purpose of this is to form a continuous arc-shaped groove in the slope of the swash plate type fluid pump/motor, and to form a spherical recess at the other end of each piston, thereby creating a connection between the swash plate and each piston. A distant relation can be achieved by interposing a pole whose part is inserted into the groove and the spherical recess.

A groove is formed on the slope of the color circumference swash plate, a spherical recess is formed in each piston, and a pole with a part inserted into the groove and the spherical recess is interposed between the swash plate and each piston. Since the piston and the slope are brought into smooth contact through the poles, and no shoes are required for this smooth contact, the structure is simple and can be manufactured at low cost.

Furthermore, if the structure is configured as described in claim 2, the pawl, the groove, and the spherical recess come into rolling contact, so power loss is reduced, and the pawl rotates about the radial line relative to the slope. Since the movement is a combination of rotation and rotation around a straight line parallel to the axis of the swash plate, the contact points between the pole and the groove and the spherical recess change one after another, extending the life of the pole.

Furthermore, if configured as described in claim 3, the amount of axial movement of the piston per unit angle rotation of the cylinder at the top dead center portion and the bottom dead center portion is reduced, so that The so-called fluid confinement phenomenon in the area is reduced, and noise is reduced.

dog 4l down Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, 1 is an axial piston type swash plate type fluid motor having a fixed casing 2, and a rotary shaft 5 is rotatably supported in the fixed casing 2 via a pair of bearings 3.4. Reference numeral 8 denotes a swash plate fixed to the fixed casing 2 and coaxial with the rotating shaft 5, and this swash plate 8 has an elliptical slope 9 on one end surface inclined at a constant angle A of less than 80 degrees with respect to the axis of the swash plate 8. has. 12 is a cylinder installed on one side of the swash plate 8 in the axial direction;
is fixed to the rotating shaft 5. A plurality of cylinder chambers I3 extending toward one side in the axial direction are formed on the other end surface of the cylinder I2 facing the slope 9, and each cylinder chamber 13
A piston 14 is slidably inserted therein, and
Between these pistons 14 and the bottom surface of the cylinder chamber 13, the pistons 14 are directed toward the swash plate 8, that is, the cylinders 12
A spring 15 is interposed to bias the spring 15 in the direction of protrusion. One end surface of the cylinder 12 and the fixed casing 2
A timing plate 18 fixed to the fixed casing 2 is interposed between the timing plate 18 and the fixed casing 2. 19.20 are arc-shaped supply boats and discharge boats formed on the timing plate 18, and these supply boats 18 and discharge boats 20 are located at the bottom dead center portion 8a of the slope 8 closest to the cylinder 12, Top dead center part 9b farthest from
They are placed on both sides of a straight line connecting the lines, slightly apart from the straight line. And those supply boats! θ and discharge bow) 20, fluid is supplied or discharged through supply and discharge passages 21 and 22 connected to a fluid source and tank (not shown).

Reference numeral 25 designates a plurality of fluid passages each having one end opened at one end face of the cylinder 12 and the other end opened at the bottom face of the cylinder chamber 13. These fluid passages 25 are connected to the supply boat 18 and the discharge port 20 by rotation of the cylinder 12. When connected to the supply boat 19, high-pressure fluid is introduced into the cylinder chamber 13 to cause the piston 14 to protrude toward the slope 9, while when connected to the discharge boat 20, the piston 14 is pushed by the slope 9. guiding the low pressure fluid pushed out from the cylinder chamber 13 to the discharge boat 20 by
Note that 26 moves the cylinder 12 toward the timing plate 1 by biasing the cylinder 12 in one direction in the axial direction.
8 to prevent fluid leakage.

As shown in FIGS. 1 and 2.3, the slope 9 is formed with a continuous elliptical groove 31 extending along the outer edge of the swash plate 8, and the groove 31 has an arcuate cross section. On the other hand, a hemispherical recess 32 is formed on the other end surface of each piston 14 . A plurality of pawls 33 are interposed between the swash plate 8 and the piston 14, and some of these pawls 33 are inserted into the groove 31 and the spherical recess 32.

Further, the center of curvature B of the groove 31 and the center of curvature C of the spherical recess 32 are separated from each other by a predetermined distance in the radial direction (in this embodiment, the center of curvature B of the groove 31 is the center of curvature C of the spherical recess 32). ), and the radius of curvature R of the groove 31 and the radius of curvature S of the spherical recess 32
are both set to the same value, which is slightly larger than the radius of curvature T of the pole 33. As a result, the pawl 33 and the groove 31 roll into contact at a point E that is slightly radially inward from the deepest part of the groove 31, while the pawl 33 and the spherical recess 32 come into contact with each other in a slightly radial direction from the deepest part of the spherical recess 32. They roll into contact at a point F that is far away from the outside. Further, in this groove 31, the rate of change of the groove bottom, that is, the amount of change in the axial direction of the groove bottom when separated by a unit distance in the circumferential direction is the middle of the slope 8 between the bottom dead center portion 8a and the top dead center portion θb. Although it is a constant value at the portion 8c, it is smaller than the constant value at the bottom dead center portion 8a and the top dead center portion 8b, and is zero here. As a result, the depth G of the groove 31 is constant at the intermediate portion θC, but becomes deeper at the bottom dead center portion 9a than at the intermediate portion 8c, as shown in FIG. It becomes shallow at 9b.

Next, the operation of one embodiment of the present invention will be explained.

First, in order to make it easier to understand, the explanation will focus on one piston 14. This piston 14 is a supply boat! 8 on the bottom dead center portion 8a side. At this time, high pressure fluid is pumped from the supply passage 21 through the supply boat 19. The piston 1 flows into the chamber 13 and
4 and press the pole 33 into the groove 31. At this time,
Since the pawl 33 rolls into contact with the downward slope groove 31 from the bottom dead center portion 9a to the top dead center portion 9b, the pawl 33,
The piston 14 receives a component force in the circumferential direction from the slope 9 and rotates the cylinder 12 and the rotating shaft 5. Here, since both the radius of curvature R of the groove 31 and the radius of curvature S of the spherical recess 32 are slightly larger than the radius of curvature T of the pole 33, the pole 3
3, the groove 31, and the spherical recess 32 come into rolling contact, reducing frictional resistance and power loss. Moreover,
Since the center of curvature B of the groove 31 and the center of curvature C of the spherical recess 32 are separated by a predetermined distance in the radial direction and are shifted from each other, the pole 33 and the center of curvature of the groove 31. The contact point with the spherical spherical concave 2 is the groove 31,
Points E and F are slightly layered from the deepest part of the spherical recess 32. As a result, the pawl 33 not only rotates around the radial line J with respect to the slope 9, but also rotates around the straight line K parallel to the axis of the swash plate 8 due to the couple at points E and F. That is, the pole 33 performs a motion that is a combination of these rotational motions. As a result, the pole 33 and the groove 3
1. The contact point with the spherical concave 2 changes one after another, and the life of the bonoshi 33 is extended. Furthermore, when the pawl 33 passes the top dead center portion 8b and the bottom dead center portion θa of the swash plate 8, the fluid in the cylinder chamber 13 flows between the supply and discharge ports 19 and 20, as in the conventional fluid motor. Communication is cut off. At this time, in the case of a conventional fluid motor, a so-called fluid confinement phenomenon occurs and a large noise is generated. however,
In this embodiment, the grooves 3 at the top and bottom dead center portions 8b and 8a are
The rate of change in the axial direction of the groove bottom of the groove 31 in the intermediate portion 9c is smaller than the rate of change in the axial direction of the groove bottom of the groove 31 in the intermediate portion 9c, and is set to zero here.
9a, the amount of axial movement of the piston 14 per unit angle of rotation of the cylinder 12 is small;
Here, it becomes zero as shown in the 5th yJ, so the degree of expansion or compression of the fluid confined in the cylinder chamber 13 is small, and no expansion or compression occurs here.
This reduces noise.

In addition, when the above-mentioned noise reduction means is not used, as shown in FIG. 6, the boat 42 of the pole check valve 41 of each piston 14 and the drain chamber 43 of the fluid motor 1
By providing a passage 44 that communicates with the above, it is possible to reduce noise by preventing cavitation. Also,
In the embodiment described above, the present invention was applied to a fluid motor, but it may also be applied to a fluid pump.Furthermore, in the embodiment described above, the center of curvature B of the groove 31 is set at a radius smaller than the center of curvature C of the spherical recess 32. By arranging it on the outside in the direction, the center of curvature B of the groove 31 and the center of curvature C of the spherical recess 32 are shifted by a predetermined distance in the radial direction, but in this invention, the center of curvature C of the spherical recess 32 is It may be shifted by arranging it radially outward from the center of curvature B of the groove 31.

4.1 As explained above, according to the present invention, the swash plate type fluid pump/motor can be made simple in structure and inexpensive.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the present invention; Fig. 2 is a perspective view of the swash plate, one piston, and the vicinity of the pawl; Fig. 3 is a cross-sectional view illustrating the state of contact between the groove, the spherical recess, and the pawl. figure,
Fig. 4 is a sectional view taken along the line I-I in Fig. 2, Fig. 5 is a graph explaining the movement state of the piston in the axial direction, and Fig. 6 is a graph similar to Fig. 3 showing another example of noise reduction. FIG. 1...Swash plate type fluid pump motor 8...Swash plate 9...Slope 9δ...Bottom dead center part 9b...Top dead center part 9c...Intermediate part
12...Cylinder 13...Cylinder chamber
14... Piston 31... Groove 3
2... Spherical recess 33... Pole B...
Center of curvature of the groove C... Center of curvature of the spherical recess R... Radius of curvature of the groove S... Radius of curvature of the spherical recess T... Radius of curvature of the pole

Claims (3)

[Claims] (1) A swash plate having a slope inclined at a constant angle with respect to the axis, a cylinder rotating around an axis coaxial with the swash plate, and a cylinder each slidably inserted into a plurality of cylinder chambers formed in the cylinder. A swash plate type fluid pump/motor comprising a piston, wherein a groove having a continuous arcuate cross section is formed on the slope, a spherical recess is formed at the other end of each piston, and a groove is formed between the swash plate and each piston. A swash plate type fluid pump/motor characterized in that a ball is partially inserted into a groove and a spherical recess. (2) The swash plate type according to claim 1, wherein the center of curvature of the groove and the center of curvature of the spherical recess are shifted in the radial direction, and the radius of curvature of at least one of the groove or the spherical recess is larger than the radius of curvature of the ball. Fluid pump motor. (3) The rate of change in the axial direction of the groove bottom located at the bottom dead center of the slope closest to the cylinder and the top dead center of the slope farthest from the cylinder is calculated between these bottom dead center and top dead center. 2. The swash plate type fluid pump/motor according to claim 1, wherein the rate of change in the axial direction of the groove bottom is smaller than the rate of change in the axial direction of the groove bottom located in the middle of the slope.