JPS632614Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a tilting part support device for a variable displacement pump or motor.

In general, variable displacement pumps and motors are designed so that the rotation axis center b of the cylinder block a is inclined at an angle of 0 to α degrees with respect to the pump axis center c, as shown in FIG.

At this time, the pump shaft center c and the trunnion center e
must match.

When rotational force is applied to the pump shaft f, the cylinder block a also begins to rotate via the piston.

At the same time, the piston begins to reciprocate relative to cylinder block a. As a result, hydraulic oil is sucked in from the suction port g and discharged from the discharge port e'.

A conventional tilting part support device for a variable displacement pump or motor is equipped with a trunnion boss k that is secured to a case x with a bolt j, as shown in Fig. 3.
A discharge port e' and a thrust bearing insertion hole m are coaxially formed in this trunnion boss k.

A collar n is fitted into the case x,
A trunnion g of a cylinder casing h is inserted into this collar n via a bearing o. A thrust bearing insertion hole r is formed in this trunnion g, and this thrust bearing insertion hole r
A thrust bearing s is fitted into the trunnion boss k, and a thrust bearing t is fitted into the thrust bearing fitting hole m of the trunnion boss k, and both thrust bearings s and t are in sliding contact with each other. A discharge passage w is formed in the trunnion g in the axial direction, and the discharge passage w is curved at a right angle.

As the hydraulic oil flows through the discharge passage w to the discharge port e', as shown in FIG.
Hydraulic pressure acts on the parts shown in .

The cylinder casing h is separated from the trunnion boss k by the hydraulic pressure of the part and the hydraulic pressure of the part offset by the hydraulic pressure of the part. This pulling force is the thrust force
Become Fs.

The hydraulic pressure in this part becomes a force that pushes the trunnion boss k, but since the trunnion boss k is fixed to the case x with a bolt j, it is received by this trunnion boss k.

As mentioned above, in the conventional tilting section, when a load is applied, the discharge port e' becomes high pressure, a thrust force Fs is generated, and the cylinder casing h is pushed downward in FIG. 1.

Therefore, friction occurs between the thrust bearing i and the cylinder casing h, which appears as hysteresis when controlling the cylinder casing tilt angle.

This places an excessive load on the trunnion boss k', which requires increasing the size of the trunnion boss k' in order to give it strength.Also, since the load is applied to the mounting bolt of the trunnion boss k', it is necessary to strengthen the bolt. Moreover, the hysteresis significantly interfered with the horsepower characteristics of the pump, making it difficult to set the horsepower characteristics.

The present invention was developed in view of the above circumstances, and its purpose is to eliminate the load applied to the trunnion boss of the tilting part on the opposite side to the trunnion boss on the discharge port side, which causes problems in terms of strength. It is an object of the present invention to provide a tilting part support device for a variable displacement pump and a motor, which eliminates the need for increasing the size, reduces hysteresis, facilitates setting of horsepower characteristics, and eliminates the need to strengthen trunnion boss mounting bolts.

The present invention will be explained below with reference to FIG.

In the drawings, reference numeral 1 denotes a case, and a sleeve 4 is fitted into a support hole 2 of the case 1 via an O-ring 3. A trunnion 7 of a cylinder casing 6 is arranged in this sleeve 4 via a bearing 5.

8 in the drawing is a trunnion boss, and this trunnion boss 8 is attached to the case 1 with bolts.
A fitting hole 9 is formed in the trunnion boss 8, and the trunnion 7 is inserted into the fitting hole 9.

An annular groove 10 is formed in the trunnion boss 8, and a discharge port 11 communicating with the annular groove 10 is formed in the trunnion boss 8.

A discharge passage 12 is formed in the axial center of the trunnion 7, and the port shape of this discharge passage 12 is T.
It is molded. That is, a guide hole 13 is formed in the diametrical direction at the tip of the trunnion 7, and this guide hole 13 opens on the circumferential surface of the trunnion 7.
The guide hole 13 communicates with the discharge flow path 12 at its central portion. The guide hole 13 opens into the annular groove 10.

Since the discharged oil flows as shown by the arrow and is discharged from the discharge port 11, the discharge flow is caused by the perpendicular part between the discharge passage 12 of the trunnion 7 and the guide hole 13 perpendicular thereto, and this perpendicular part facing the discharge flow. Opposite pressures act on the curved portion of the passage 12, and no thrust force is applied to the trunnion boss on the opposite side.

That is, as oil flows from the discharge passage 12 to the discharge port 11 through the guide hole 13, hydraulic pressure acts on the portions indicated by ',',',',',' in FIG.

However, the hydraulic pressure in the section ′ and the hydraulic pressure in the section ′ are canceled out, the hydraulic pressure in the section ′ and the hydraulic pressure in the section ′ are canceled out, and the hydraulic pressure in the section ′ and the hydraulic pressure in the section ′ are canceled out. Ru.

Therefore, thrust force Fs is not generated.

The present invention has been described in detail above, and the trunnion boss 8 is provided on the circumferential surface of the insertion hole 9 of the trunnion boss 8 that supports the trunnion 7 of the cylinder casing 6.
An annular groove 10 communicating with a discharge port 11 provided in the trunnion 7 is formed, and a guide hole 13 is formed in the radial direction of the trunnion 7, and the guide hole 13 is opened in the circumferential surface of the trunnion 7 and is formed in the axial direction of the trunnion 7. Connecting the discharge flow path 12 to the middle part of the guide hole 13,
Since the opening of the guide hole 13 is open to the annular groove 10, the discharge oil flowing through the discharge flow path 12 is a discharge flow where the orthogonal part of the guide hole 13 that is perpendicular to the discharge flow path 12 and the orthogonal part are opposed to each other. Opposite pressures are applied to the curved portion of the passage 12 to prevent thrust force from being applied to the opposite trunnion boss.

In this way, no load is applied to the trunnion boss of the tilting part on the opposite side to the trunnion boss 8, there is no need to increase the size due to strength problems, and the hysteresis is reduced, making it easy to set the horsepower characteristics. This eliminates the need to strengthen the trunnion boss mounting bolt.

[Brief explanation of drawings]

Figure 1 is a longitudinal sectional view of the variable displacement pump and motor.
Fig. 2 is an explanatory diagram of the relationship between the cylinder block and the pump shaft, Fig. 3 is a longitudinal sectional view of a tilting part support device in a conventional variable displacement pump motor, and Fig. 4 is a longitudinal sectional view of an embodiment of the present invention. FIG. 5 is an explanatory diagram of the hydraulic action in the tilting portion support device of the variable displacement pump and motor according to the present invention. 6 is the cylinder casing, 7 is the trunnion, 8
1 is a trunnion boss, 10 is an annular groove, 11 is a discharge port, and 13 is a guide hole.

Claims (1)

[Scope of utility model registration request] An annular groove 10 communicating with a discharge port 11 provided in the trunnion boss 8 is formed on the circumferential surface of the fitting hole 9 of the trunnion boss 8 that supports the trunnion 7 of the cylinder casing 6, and a guide hole is formed in the trunnion 7 in the diametrical direction. The guide hole 13 is opened in the circumferential surface of the trunnion 7, and the discharge flow path 12 formed in the axial direction of the trunnion 7 is connected to the middle part of the guide hole 13, and the opening of the guide hole 13 is connected to the middle part of the guide hole 13. The annular groove 1
A variable displacement pump characterized by being opened to 0,
A tilting part support device in a motor.