JPH0275774A - Swash plate piston pump motor - Google Patents

Abstract

PURPOSE:To enable the constant occurrence of a given shoe push-back action by a method wherein an annular leaf spring around a retainer mounted to a cylinder in the vicinity of a shoe is formed in a modified curve shape in cross section to reduce an elastic modules, and a range of a relative angle between the leaf spring and a mating member is specified. CONSTITUTION:When a piston 4 is returned to the end wall side (right side), a shoe 6 coupled to a piston head part 5 is about to separate form a swash plate 7. A return mechanism to prevent the occurrence of this motion comprises a press plate 35 engaged with a shoe 6, a retainer 36 mounted to a cylinder 2, and a leaf spring 37 located between the press plate 35 and the retainer 36. The leaf spring 37 is stretched annularly around the retainer 36 and is formed so as to have a curved radial cross section. A tapered inner peripheral part 40 and an outer peripheral part 42 are integrally formed to the leaf spring 37. The inner peripheral part 40 is brought into pressure contact with an outer peripheral surface 38 of the retainer 36 from the swash plate 7, and the pressure contact angle (d) is set to 10 deg. or more and 25 deg. or less.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a swash plate type piston pump motor, and more specifically, the present invention relates to a swash plate type piston pump motor, and more specifically, a swash plate is used to convert axial movement of a piston operated by hydraulic pressure into rotational movement. Related to piston pump motor for conversion [Prior art] This company's piston pump motor has a reciprocating piston built into a cylinder attached to the output shaft (rotating shaft). The inclined swash plate portion is provided in a fixed state. One end of the piston contacts the swash plate via a shoe that is a universal joint, and the other end faces a hydraulic chamber inside the cylinder. Hydraulic pressure is supplied to the hydraulic chamber from the outside, and the axial movement of the piston due to the hydraulic pressure is converted into rotational movement by the action of the swash plate.

In such a construction, the shoes tend to move away from the swash plate during the movement stroke in which the piston moves away from the swash plate, and a spring is used to prevent this. An example of such a spring is described in Japanese Utility Model Application No. 62-3972. In the structure described in that publication, an annular leaf spring whose radial cross section is curved in an arc shape is used as the spring.

The inner peripheral part of the leaf spring engages with a retainer that is integrated with the piston and output shaft, and the other end is connected to the shoe via a presser plate (2).

[Problems to be Solved by the Invention] However, the leaf spring described in the above publication has the same radial cross-sectional shape over the entire circumference, in other words, the inner diameter and outer diameter are constant over the entire circumference.

Therefore, the spring constant is very high, for example 100 kgf'
/ More than a dragon. For this reason, if the amount of compression of the spring in the assembled state is even slightly incorrect, the pressing load of the spring will be significantly incorrect, and as a result, the spring will no longer perform its intended function.

Therefore, in order to obtain a predetermined function, it is necessary to strictly control the axial dimensions and assembly accuracy of each component incorporated into the piston pump motor, which makes manufacturing difficult and increases manufacturing costs.

Furthermore, when using a leaf spring with an arcuate cross section as described in the above publication, unlike the case where a simple compression coil spring is compressed in the axial direction, the force that presses the shoe against the swash plate is equal to that of the leaf spring. It is greatly influenced by the relative angle between it and the other member. Therefore, in order to obtain a predetermined function, it is necessary to set the above-mentioned relative angle in consideration of this point, but the above-mentioned publication does not describe a specific value or range of the relative angle.

The present invention uses a leaf spring with a curved cross-sectional shape, improves the shape of the leaf spring to lower its elastic modulus, and furthermore, the relative angular range between the leaf spring and the mating member is The aim is to provide a device that has been determined to

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a cylindrical cylinder connected to an output shaft, in which a plurality of hydraulically driven pistons that reciprocate in the axial direction are spaced apart in the circumferential direction. A shoe is installed separately and has a plurality of connecting parts spaced apart from each other in the circumferential direction, one end of the piston is connected to the connecting part, and the shoe is seated via a pressure contact sliding surface on the opposite side of the piston. The structure includes a swash plate portion fixed to the casing, a cylindrical retainer having a spherical outer circumferential surface provided on the cylinder near the shoe, and an annular leaf spring provided around the retainer.

Further, in the present invention, the corrugated plate spring has a tapered inner peripheral part whose diameter becomes smaller as it goes toward the swash plate, and a curved part from the large diameter end of the inner peripheral part to the radially outer side and the swash plate. The inner peripheral surface of the leaf spring is integrally provided with an outer peripheral portion that extends in a tapered shape toward the side, and the inner peripheral surface of the inner peripheral portion of the leaf spring is 10@25 or more with respect to the direction perpendicular to the pressure-contact sliding surface.
Pressed against the spherical outer peripheral surface of the retainer at a first angle of less than °,
The outer periphery of the leaf spring is pressed against the sliding surface by 15@4 or more.
A plurality of extension parts are provided on the outer periphery of the leaf spring, which are inclined at a second angle of 0° or less, and which extend between the two adjacent connecting parts, and the tip edges of the extension parts are pressed against the pressure-contact slide of the shoe. It has a structure in which it is pressed against the surface opposite to the moving surface.

[Function] According to the above structure, the leaf spring has a plurality of outwardly extending portions spaced apart in the circumferential direction, in other words, the leaf spring has a plurality of outwardly extending portions spaced apart in the circumferential direction on the outer periphery. It has a flaw. Moreover, each of the extension parts is inserted between adjacent connection parts. Therefore, compared to the leaf spring having a constant outer diameter as described in the above-mentioned publication, that is, the leaf spring whose entire outer periphery is circular and located radially inward from the connection part of the shoe, the leaf spring according to the present invention is The elastic modulus of a leaf spring is lower than that of a spring.

By installing such a leaf spring at an appropriate angle as described above, even if there is some error in the amount of compression of the leaf spring in the assembled state, the force exerted from the leaf spring on the shoe or retainer will be within the specified range. maintained, and a predetermined shoe pushing back action can always be obtained.

[Embodiment] In FIG. 1, in a piston pump motor according to an embodiment of the present invention, a cylindrical cylinder 2 is connected to an outer peripheral spline of an output shaft 1. A plurality of holes 3 extending in the axial direction (direction parallel to the output shaft 1) are provided in the cylinder 2 at intervals in the circumferential direction, and a piston 4 is fitted into each hole 3. 63
is open at one end surface of the cylinder 2, and one end of each piston 4 protrudes from the opening. A spherical head 5 is formed at the protruding end of the piston 4.

Each head 5 is tightly fitted into the spherical concave surface of the shoe 6. The surface of the shoe 6 opposite to the piston 4 is slidably pressed against the surface of the swash plate 7. The swash plate 7 is a flat annular plate, and is fixed to the inner surface of the housing assembly 10 in an inclined position with respect to the output shaft 1.

The surface of the cylinder 2 opposite to the swash plate 7 is slidably seated on the valve plate 11. The valve plate 11 is attached in close contact with the end wall 12 of the housing assembly 10. A hole into which the end of the output shaft 1 fits is provided in the center of the inner surface of the end wall 12, and the end of the output shaft 1 is supported by the inner periphery of the hole via a bearing 19.

The end wall 12 and the valve plate 11 are provided with a series of inlet oil passages and outlet oil passages (only one oil passage 13 is shown) that communicate with an external oil passage (not shown). An oil passage connecting the oil passage 13 and the hydraulic chamber 14 for the piston 4 is provided. The hydraulic chamber 14 is formed in a space of the hole 3 closer to the end wall 12 than the piston 4.

During operation, the piston 4 pushes the shoe 6 against the swash plate 7 due to hydraulic pressure introduced from the outside into the hydraulic chamber 14 via the oil passage 13, and the reaction force causes the piston 4 to move in the circumferential direction of the output shaft 1. The cylinder 2 and the output shaft 1 rotate accordingly.

Of course, as the cylinder 2 rotates, the oil passages connected to the hydraulic chambers 14 are periodically switched between the artificial oil passages and the outlet oil passages, and the force applied from each hydraulic chamber 14 to the piston 4 also changes from the output shaft 1.
The output shaft 1 and the cylinder 2 are switched between the positive direction (the pushing direction) and the negative direction (the pulling direction) every half rotation, thereby causing the output shaft 1 and the cylinder 2 to rotate continuously.

In the above operation, in order to smoothly slide the shoe 6 and the swash plate 7 on the pressure contact sliding surface 15 that presses against each other, the piston 4 has an oil passage 16 extending from the hydraulic chamber 14 to the tip of the head 5. The shoe 6 is provided with a throttle oil passage 17 that connects the oil passage 16 and the pressure-contact sliding surface 15.

In addition, in the above-mentioned operation, when the piston 4 returns to the end wall 12 side, the shoe 6 connected to the piston head 5 also moves in the same direction and tries to separate from the swash plate 7. In order to prevent this, the shoe 6 is also provided with a return mechanism as described below.

Before explaining the return mechanism, the connection structure between the piston head 5 and the shoe 6 will be explained in more detail.

In FIG. 2, which is an enlarged schematic diagram of FIG. 1, the shoe 6
is provided with a generally cylindrical connecting portion 30 protruding toward each piston 4 side, and the head 5 is slidably fitted into a spherical concave surface formed inside the connecting portion 30. Also, these connecting parts 3
0 are located at a gap 31 from each other in the circumferential direction of the swash plate, as shown in FIG. The portion extends radially outward from the connecting portion 30 to form a flange 32 .

The return mechanism includes a presser plate 35 that engages with the shoe 6.
, a retainer 36 provided on the cylinder 2, and a presser plate 3.
5 and a leaf spring 37 interposed between the retainer 36 and the retainer 36.

The presser plate 35 is an annular plate extending along the swash plate 7, has a plurality of holes into which the respective connecting parts 30 fit, and is seated on the flange 32 from the side opposite to the swash plate 7 around the connecting parts 30. .

The retainer 36 is formed of a generally cylindrical portion that integrally projects from the inner peripheral portion of the cylinder 2 to the vicinity of the swash plate 7, and has a spherical outer peripheral surface 38.

The leaf spring 37 extends annularly around the retainer 36 and is curved in radial cross section. The leaf spring 37 has
A tapered inner peripheral portion 4 that becomes smaller in diameter as it goes toward the swash plate 7 side.
0, and an outer circumferential portion 4 that extends in a tapered shape from the large-diameter end of the inner circumferential portion 40 via the curved portion 41 radially outward and toward the swash plate 7.
2 are integrated.

The inner circumferential surface of the inner circumferential portion 40 is in pressure contact with the outer circumferential surface 38 of the retainer 36 from the swash plate 7 side, and the pressure contact angle d, that is, the direction perpendicular to the pressure contact sliding surface 15 (second The angle d of the inner circumferential surface of the inner circumferential portion 40 in pressure contact with respect to the direction indicated by the line N in the figure is set to 10'' or more and 250 or less.

As shown in FIG. 3, the outer peripheral portion 42 is provided with a plurality of extension portions 43 that enter the gaps 31 between the connecting portions 30. More specifically, the outer peripheral edge of the leaf spring outer peripheral part 42 is provided with notches 45 spaced apart in the circumferential direction into which a part of each of the connecting parts 30 (the part near the leaf spring inner peripheral part 40) enters. An extension portion 43 is formed between the notches 45. As shown in FIG. 2, the outer peripheral portion 42 is pressed against the surface of the holding plate 35 of the shoe 6 on the side opposite to the swash plate 7 at the tip of the extension portion 43, and the shoe 6 is pressed against the swash plate 7 via the holding plate 35. I'm forcing it. Further, the pressure contact angle D between the outer peripheral portion 42 and the surface of the flange 32 (more precisely, the angle of the outer peripheral portion 42 with respect to the direction parallel to the pressure contact sliding surface 15) is set to be twice or less than the pressure contact angle d. It is.

As described above, the leaf spring 37 has a long maximum length in its radial cross section (the length of the portion including the extension portion 43), and is provided with notches 45 at a plurality of locations on the outer periphery. Therefore, the leaf spring 37 acts as a flexible spring with a low elastic modulus. The above-mentioned angle d1D also depends on the original function of the leaf spring 37 and various conditions (for example, friction between the leaf spring 37 and the retainer 36, stress applied to the leaf spring 37, and the difference between the leaf spring 37 and the shoe 6).
The pressure contact angle d of the leaf spring 37 with respect to the presser plate 35 and the retainer 36 is
By setting D within the above-mentioned range, a force in the direction of pushing the shoe 6 back against the swash plate 7 can be accurately obtained, and this was confirmed through calculations and the like during the development stage of the present invention.

Therefore, even if there is some error in the amount of compression of the leaf spring 37 in the assembled state, the force exerted from the leaf spring 37 on the shoes 6 and the retainer 36 is maintained within a predetermined range, and the force exerted on the shoes 6 and the retainer 36 is maintained within a predetermined range. , it is possible to maintain pressure contact between them at all times while maintaining the pressure contact load between them within a predetermined range.

Further, in the above-described structure, the cylinder 2 can be always brought into pressure contact with the housing end wall 12 by the force exerted from the leaf spring 37 on the presser plate 35.

[Effects of the Invention] As explained above, in the present invention, the shape and mounting structure of the leaf spring 37 are improved, and the first part of the leaf spring 37 is improved.
Since the second pressure contact angles d and D are set within optimal ranges, an appropriate pushing back force can be reliably applied to the shoe 6. In other words, the push-back force is less affected by dimensional errors and assembly errors of each part, so
Manufacture and assembly of each part can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is an enlarged schematic diagram of FIG. 1, and FIG. 3 is a schematic diagram of FIG. DESCRIPTION OF SYMBOLS 1... Output shaft, 2... Cylinder, 4... Piston, 6... Shoe, 7... Swash plate, 10... Casing assembly, 11... Valve plate, 15...・Pressure sliding surface, 3
o... Connecting portion, 36... Retainer, 37... Leaf spring, 38... Spherical outer peripheral surface, 40... Leaf spring inner peripheral part,
41... Leaf spring curved portion, 42... Leaf spring outer peripheral portion, 4
3...Extension part, D...Second angle, d...First angle Patent applicant Kawasaki Heavy Industries, Ltd.

Claims (1)

[Claims] A shoe in which a plurality of hydraulically driven pistons that reciprocate in the axial direction are installed at intervals in the circumferential direction in a cylindrical cylinder connected to an output shaft, and the shoe has a plurality of connecting parts spaced apart in the circumferential direction. , a swash plate portion is fixed to the casing, one end of the piston is connected to the connecting portion, and the shoe is seated via a pressure contact sliding surface on the opposite side of the piston;
A cylindrical retainer having a spherical outer peripheral surface is provided in the cylinder near the shoe, an annular leaf spring is provided around the retainer, and the leaf spring has a tapered inner peripheral part whose diameter becomes smaller toward the swash plate; An outer circumference extending radially outward and toward the swash plate from the large-diameter end of the inner circumference through the curved portion is integrally provided, and the inner circumferential surface of the inner circumference of the leaf spring is connected to the pressure-contact slide. The first angle of 10° or more and 25° or less with respect to the direction perpendicular to the moving surface
The outer periphery of the leaf spring is pressed against the spherical outer circumferential surface of the retainer at an angle, and the outer periphery of the leaf spring is inclined at a second angle of 15° or more and 40° or less with respect to the pressure-contact sliding surface. a plurality of extension portions that fit between the connecting portions;
A swash plate type piston pump motor characterized in that a tip end edge of the extension portion is brought into pressure contact with a surface of the shoe opposite to the pressure contact sliding surface.