JPH039172A - Ball joint mechanism of hydraulic pump or the like - Google Patents

Abstract

PURPOSE:To prevent the deformation of a ball part and the flawing of surfaces by using a shape memory alloy in a calked part and restoring a calked shape, stored in the calked part, while holding the ball part in the calked part so as to connect a piston to a shoe. CONSTITUTION:First a dummy ball D of a piston 8 is adapted to a recessed part 10 in a shoe 9, and a calk-shaped original shaped part 11c is formed by calking a protruding part 11b of a calked part 11 to the inner. Next, a shoe 9 is applied with heat treatment, and a ball shape of the original shaped part 11c is stored in a mother material. Next by holding the calked part 11 at not more than a martensite transformation start temperature, external force is applied to the calked part 11 to plastically deform the original shaped part 11c to the outer, and the shape of the original shaped part 11c is returned to the shape of the protruding part 11b. Next, a ball part 8a of the piston 8 is brought into contact with the recessed part 10 of the shoe 9, and the piston 8 is mounted to the shoe 9. Next by heating the calked part 11 to not less than an austenite transformation end temperature, the calk-shaped original shaped part 11c, stored in the calked part 11 in the second process, is restored, and the piston 8 is connected to the shoe 9.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a ball joint mechanism for a hydraulic pump or the like that connects a piston and a shoe.

(Prior Art) In the conventional hydraulic pump shown in FIG. 7, a plurality of piston holes 1a are formed in a cylinder block, and an input shaft 2 is inserted through the cylinder block l.

Pistons 3 are slidably inserted into the piston holes 1a, and a swash plate 4 is provided opposite the tips of the pistons 3.

A shaft hole 4a is formed in the swash plate 4, and the input shaft 2 is passed through the shaft hole 4a, and the swash plate 4 is tilted with respect to the axis of the input shaft 2 and fixed to a pump case (not shown). ing.

A shoe plate 5 is provided on the side surface of the swash plate 4 on the piston 3 side, and a shoe 6 is provided between the shoe plate 5 and the piston 3. And Shoe 6
One side is brought into slidable contact with the shoe plate 5, and the other side is connected to the piston 3.

The ball joint mechanism between the piston 3 and the shoe 6 shown in FIG. ing.

Then, the ball portion 3a formed at the tip of the piston 3 is brought into contact with the recess 7, and the tip of the caulking portion 6a is caulked inward, and the caulking portion 6a embraces the ball portion 3a, so that the piston 3 and the shoe When the cylinder block 1 is rotated by input to the input shaft 2, the plurality of pistons 3 revolve around the input shaft 2 together with the cylinder block 1.

When the piston 3 revolves, the shoe 6 connected to it
Although the piston 3 rotates on the shoe plate 5, since the shoe plate 5 is inclined together with the swash plate 4, the piston 3 eventually reciprocates in the left-right direction in the drawing.

Then, when the piston reciprocates as described above,
The shoe 6 and the ball portion 3a of the piston 3 swing,
This shoe 6 allows the ball portion 3a to exhibit bearing movement.

(Problems to be Solved by the Present Invention) In the conventional ball holding mechanism of a hydraulic pump or the like as described above, an external force is applied to the caulking portion 6b of the shoe 6, and the caulking portion 6b is
b was caulked to the ball portion 3a to connect the shoe 6 and the piston 3.

When the caulking part 6b is caulked, the metal caulking part 6b is plastically deformed, so a large external force is required, and this external force also acts on the ball part 3a via the caulking part 6b.

In this way, the external force when caulking the caulking part 6b also acts on the ball part 3a, so the effect of this external force may deform the sphere or damage its surface, impairing its surface roughness. . Furthermore, if the surface of the sphere is coated with ceramic or the like, this coating layer will crack or peel.

For this reason, the conventional ball joint mechanism has a problem in that its bearing function deteriorates.

There is also the problem that materials such as ceramics that are easily damaged by external force during caulking or soft materials that are easily deformed or damaged cannot be used for the ball portion.

Furthermore, since a caulked shape is molded each time for a large number of spherical parts, the caulked shape becomes non-uniform, resulting in large variations in molding accuracy.

Therefore, there was also a problem that the quality of the ball joint mechanism was not stable.

An object of the present invention is to provide a ball joint mechanism for a hydraulic pump or the like that can maintain stable bearing function.

(Means for Solving the Problems) In order to achieve the above object, the present invention forms a spherical portion at the tip of one of a pair of opposed pistons and shoes, and forms a spherical portion on the outer periphery of the other one. A hydraulic pump, etc., in which a caulking part is provided, an arc-shaped recess is formed inside the caulking part, the ball part is brought into contact with the recess, and the tip of the caulking part is deformed to connect a piston and a shoe. This is a dispute based on the premise of a ball joint mechanism.

Based on the above mechanism, this invention uses a shape memory alloy in the caulking part to restore the caulked shape memorized in the caulking part, and also connects the piston and shoe by embracing the ball part in the caulking part. It is configured to do this.

(Action of the present invention) As described above, since a shape memory alloy is used in the caulked portion provided on the piston or the shoe, the piston and the shoe can be connected by restoring the caulked shape stored in the caulked portion in advance. be able to.

Therefore, there is no need to forcefully caulk the caulked portion by applying external force.

(Effects of the present invention) According to the ball joint mechanism of the hydraulic pump, etc. of the present invention, there is no need to apply external force to the caulking part to connect the piston and shoe, so the ball part is not deformed or the surface is damaged. It does not cause any damage to the surface roughness due to adhesion, and even if the surface of the sphere is coated with ceramic or the like, the coating layer will not crack or peel.

Therefore, the bearing function of the ball joint mechanism of the hydraulic pump or the like can also be maintained.

Furthermore, even materials such as ceramics that are easily damaged by external force during caulking or soft materials that are easily deformed or damaged can be used for the ball portion.

Furthermore, since a single dummy ball is used to form a caulked shape on a large number of caulked parts, the caulked shape is made uniform, and variations in molding accuracy are reduced, making it possible to stabilize the quality.

(Embodiment of the present invention) In the first embodiment shown in FIG. 1, a spherical portion 8a is integrally formed at the tip of the piston 8, and a shoe 9 is provided opposite to the spherical portion 8a.

The shoe 9 is made of a shape memory alloy with a unidirectional element, and a caulked portion 11 is integrally formed on the outer periphery of the shoe 9, and a caulked portion 11 is formed on the inside thereof to have the same radius of curvature as the spherical portion 8a. An arcuate recess 10 is formed.

Further, the caulked portion 11 has a stepped portion lla formed at its inner end, and the inner diameter of the caulked portion 11 is made larger than the diameter of the spherical portion 8a. When the spherical portion 8a of the piston 8 is brought into contact with the recess 10, the tip of the caulked portion 11 projects in the direction of the piston 8 from the axis-perpendicular center line XX of the spherical portion 8a. The protruding end side is a protrusion 11b.

Then, the spherical portion 8a of the piston 8 is brought into contact with the recessed portion lO of the shoe 9, and the protrusion 11b of the caulking portion 11 is deformed inward, thereby connecting the piston 8 and the shoe 9.

The specific assembly process for connecting the piston 8 and the shoe 9 is completed through the processes (A) to (E) shown in FIG. 2.

(a) A dummy ball, which is a dummy of the piston 8, is brought into contact with the concave portion 10 of the shoe 9. Then, the protrusion 11b of the caulking portion 11 is caulked inward, and the original shape portion 11 in the caulked shape is
Form c.

The diameter of the dummy ball is the diameter of the piston 8 in this example.
The dimensional difference is kept within 10 μm with respect to the diameter of the spherical portion 8a.

Moreover, when the original part 11c is formed by caulking the caulking part 11, 20 to 30 g
A gap of m is maintained.

(b) The shoe 9 formed as described above is heat-treated to memorize the shape of the original portion lie, which is the caulked shape, in the base material.

(c) Caulking part 1 in which the caulking shape is memorized as described above
1 is held at a temperature below the martensite deformation start temperature, and an external force is applied to the caulked portion 11 to plastically deform the original portion 11C outward. Then, the shape of the original portion lie is returned to the shape of the protrusion 11b.

(d) The piston 8 is attached to the shoe 9 by bringing the spherical portion 8a of the piston 8 into contact with the recess 10 of the shoe 9.

(E) The caulking portion 11 of the shoe 9 mounted as described above is heated to a temperature equal to or higher than the austenite transformation end temperature. Then, the caulking portion 11 is restored to its original shape, which is the caulking shape memorized in the second step, and the piston 8 and shoe 9 are
Complete the connection with.

The piston 8 and the shoe 9 that have been connected as described above are assembled by installing the piston 8 into the piston hole 1a of the cylinder block 1 as shown in FIG.
One side of the shoe plate 5 is slidably contacted with a shoe plate 5 provided on the swash plate 4. Then, when cylinder block 1 rotates,
The piston 8 reciprocates and the recess lO of the shoe 9 and the spherical part 8a of the piston 8 hold the function of a bearing in a freely swinging manner, which is the same as in the prior art.

According to the embodiment described above, the caulked shape stored in the caulking portion 11 is restored, and the ball portion 8a is held in the caulking portion 11 to connect the shoe 9 and the piston 8.

In the second embodiment shown in FIG. 3, the relationship between the piston and shoe of the first embodiment is reversed.

That is, a shape memory alloy is used for the piston 12, a caulking ff114 is integrally formed on the outer circumference of the piston 12, and a ball portion 15a is formed on the shoe 15 facing the piston 12.

Then, an arc-shaped recess 13 is formed inside the caulking portion 14 formed on the piston 12, and the caulking portion 1
A stepped portion 14a is formed at the inner end of the shoe 15, and the inner diameter of the caulked portion 14 is made larger than the diameter of the spherical portion 15a formed on the shoe 15.

The caulking portion 14 as described above has a ball portion 15 in the recess 13.
When a is brought into contact with the tip of the caulked part 14, the ball part
It is made to protrude toward the shoe 15 side from the axis-perpendicular center line XX of a, and its protruding end side is defined as a protrusion 14b.

The method of connecting the ball portion 15 and the caulking portion 14 as described above is exactly the same as in the first embodiment.

In the third embodiment shown in FIG. 4, the caulking portion is formed separately from the piston or the shoe, and a shape memory alloy is used for the caulking portion to connect the piston and the shoe.

That is, in the third embodiment, a convex portion 17 is formed on one side of the shoe 16, and an arc-shaped concave portion 17a is formed at the tip of the convex portion 17. A cylindrical caulking member 18 made of a shape memory alloy is fitted onto the outer periphery of the convex portion 17.

The caulking member 18 configured as described above has an inner diameter larger than the diameter of the spherical portion 8a. The tip of this caulking member 18 is made to protrude toward the piston from the axis-perpendicular center line XX of the bulb 8a when the bulb 8a is brought into contact with the recess 17a, and the protruding end side is connected to the protrusion. 18
This is the same as in the first embodiment.

The fourth embodiment is characterized in that the caulking portion is composed of a completely different caulking member 18 independent from the shoe and the piston, and this caulking member 18 is used to connect the shoe and the piston in several ways. is the same as in the first embodiment.

In the fourth embodiment shown in FIG. 5, a claw portion 19a is formed at one end of a caulking member 19 made of a shape memory alloy.

Further, an annular groove 20a is formed on the outer periphery of the shoe 20, and the claw portion 1 of the caulking member 19 is inserted into the annular groove 20a.
9a is fitted. The configuration other than this is the same as that of the third embodiment.

In the fifth embodiment shown in FIG. 6, a convex portion 22 is formed on one side of a piston 21, and an arc-shaped concave portion 22b is formed at the tip of the convex portion 22.
At the same time, an annular groove 22a is formed at the inner end.

Further, a claw portion 19a is formed at one end of a shape memory alloy caulking member 19, which is a portion of the piston 21. It fits into the annular groove 22a of.

The configuration other than this is substantially the same as the above four embodiments.

Note that each of the caulking members 18 and 19 of the third to fifth embodiments shown in FIGS. 4 to 6 above constitutes a caulking portion of the present invention.

As described above, in the first to fifth embodiments, a shape memory alloy is used for the caulked portion provided on the piston or shoe. Further, in the caulking portion, a caulking shape connecting the piston and the shoe is formed using a dummy ball, and this caulking shape is stored in advance in the base material that is the caulking portion. and,
When connecting the piston and the shoe, the memorized caulking shape is restored and the caulking part embraces the ball part.

In this way, the piston and shoe 8- are connected by restoring the memorized shape of the caulked portion, so there is no need to apply external force to the caulked portion.

Since no external force is required for caulking, the sphere will not be deformed or its surface will be scratched and the surface roughness will not be impaired. Furthermore, even if the surface of the sphere is coated with ceramic or the like, the coating layer will not crack or peel.

Therefore, the bearing function of the ball joint mechanism such as the hydraulic piston can also be maintained.

Furthermore, since a single dummy ball is used to form the caulked shape on a large number of caulked parts, the caulked shape is made uniform and variations in molding accuracy are reduced.

Therefore, it is also possible to stabilize the quality of the ball joint mechanism such as the hydraulic pump.

[Brief explanation of drawings]

Figures 1 to 6 show embodiments of the present invention, with Figure 1 being a sectional view of the first embodiment, Figure 2 being an assembly process diagram for connecting the piston and shoe, and Figures 3 to 6. are sectional views showing the second to fifth embodiments, and Fig. 7.8 shows the conventional mechanism.
FIG. 7 is a sectional view of the hydraulic pump, and FIG. 8 is an enlarged sectional view of the main parts. 8... Piston, 8a... Ball part, 9.20... Shoe, 10.13.17a, 22 b-... Recessed part, 11
．． 14,... caulking part, 12.21... piston,
15a... Ball part, 19... Caulking member.

Claims (1)

[Claims] A spherical part is formed at the tip of one of a pair of opposing pistons and shoes, a caulked part is provided on the outer periphery of the other, and an arc-shaped recess is formed inside this caulked part, and this recess In a ball joint mechanism such as a hydraulic pump that connects a piston and a shoe by bringing the ball part into contact with the body and deforming the tip of the caulking part, a shape memory alloy is used in the caulking part to cause memory in the caulking part. A ball joint mechanism for hydraulic pumps, etc. that restores the caulked shape and connects the piston and shoe by embracing the ball at the caulking part.