JPH01134077A - Swash plate type axial piston pump and motor - Google Patents

Abstract

PURPOSE:To cope with the pinch force of a piston by constituting it with a connecting piston fitted in an insert hole of a support block set up between a cylinder block and a swash plate and a sealing piston inserted into a cylinder hole connected together free of rocking motion. CONSTITUTION:A cylinder block 4 is fitted in a turning shaft 2 supported on a car body 1, and a piston 6 is fitted in the cylinder hole 5. This piston 6 is made free of rocking motion along a swash plate 8 rockably supported on a case body 1. In the above constitution, a support block 20 with a piston insert hole 21 is set up between the cylinder block 4 and the swash plate 8, and the support block 20 is fitted in the turning shaft 2. The piston 6 is constituted with a connecting piston 23 inserted into the piston insert hole 21 and a sealing piston 22 inserted into the cylinder hole 5 connected together free of rocking motion.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a swash plate type piston pump motor.

[Conventional technology]

As a swash plate type piston pump/motor, for example, the one shown in FIG. 2 is known.

That is, a shaft 2 is rotatably supported by a bearing 3 across one side wall 1a and the other side wall 1b of the case body 1, and the spline hole 4a of the cylinder block 4 is connected to the spline portion 2a of the shaft 2.
Spline e? At the same time, a piston 6 is fitted into the cylinder hole 5 of the cylinder block 4 to form a cylinder chamber 7, and the piston 6 is connected to the case body 1.
The swash plate 8 is slidably supported on the valve plate 9 and the cylinder chamber 7 is slidable along the front surface 8a of the swash plate 8.
The boat 11 is connected to the boat 11 formed on the other side wall 16 of the case body 1 through the hole 10, and pressurized oil is supplied from the boat 11 to the cylinder chamber 7 to rotate the cylinder block 4 and drive the shaft 2. This is a swash plate type piston pump/motor in which oil in a cylinder chamber 7 is discharged from a boat 11 by driving a cylinder block 4 and reciprocating a piston 6.

[Problem that the invention seeks to solve]

In such a swash plate type piston pump/motor, a prying force acts when the piston 6 slides along the front surface 8a of the swash plate 8, and this prying force also acts on the cylinder block 4 via the piston 6. An overturning moment occurs in the cylinder block 4.

In other words, a piston straining force Frp corresponding to the hydraulic pressure P acting on the piston 6 and the swash plate angle θ acts on the piston 6,
Supporting reaction force Fr1 against the piston straining force Prp,
Since Fr2 acts on the cylinder block 4, an overturning moment M is generated in the cylinder block 4 by the supporting reaction forces Fr1 and Fr2.

This overturning moment M is supported by the spline fitting between the shaft 2 and the cylinder block 4 and the sliding surfaces of the cylinder block 4 and valve plate 9. Dynamic resistance may increase or oil pressure may not be balanced, which may cause seizure on the sliding surface. This becomes more noticeable as the speed and pressure increase.

Further, since the piston 6 becomes oblique within the cylinder hole 5 due to the piston prying force Frp, the cylinder hole 5 is worn out early, and when the piston is operated for a long time, the volumetric efficiency changes significantly over time.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a swash plate type piston pump/motor that can solve the above problems.

[Means and actions for solving the problem] A support block having a piston insertion hole is provided between the cylinder block and the swash plate, and this support block is fitted and connected to the shaft, and the piston is connected to the piston. A small-diameter connecting piston fits into the piston insertion hole and a large-diameter seal fits into the cylinder hole. The pistons are connected so as to be swingable to form a piston, so that the cylinder hole does not wear out prematurely due to piston prying force.

〔Example〕

The present invention will be described in detail below with reference to FIG. In addition,
The same members as the conventional one have the same symbols.

Support block 20 between cylinder block 4 and swash plate 8
is arranged, and the spline hole 20a of this support block 20 is
is spline-fitted to the spline portion 2a of the shaft 2, and a piston insertion hole 21 is bored in the support block 20, and the axially intermediate portion of the piston 6 is slidably inserted into the piston insertion hole 21.

Therefore, the piston prying force Frp due to the hydraulic pressure P and the swash plate angle θ can be supported by the support block 20, and the support reaction forces Fr1 and Fr2 can be transmitted to the shaft 2 via the support block 20, and the cylinder block 4 No overturning moment acts on the

The piston 6 consists of a large-diameter sealing piston 22 fitted into the cylinder hole 5 and a small-diameter connecting piston 23 fitted into the piston insertion hole 21, and the connecting piston 23 has a smaller diameter than the cylinder hole 5. At the same time, the distal end spherical portion 24 of the sealing piston 22 is pivotally fitted into the rear end spherical recess 25 of the connecting piston 23, and the radial play is prevented so that radial force is not applied to the sealing piston 22. The connecting piston 23 is inserted into the piston insertion hole 21 of the support block 20.

〔Effect of the invention〕

The piston prying force Frp due to the hydraulic pressure P acting on the piston 6 and the swash plate angle θ is supported by the support block 20, and the supporting reaction forces Fr1 and Fr2 can be transmitted to the shaft 2, and the piston prying force Frp acts on the cylinder block 4. There's nothing to do.

Therefore, since no overturning moment is generated in the cylinder block 4, seizure does not occur on the sliding surface between the cylinder block 4 and the valve plate 9. Furthermore, the connecting piston 23, which receives the piston prying force, has a smaller diameter than the cylinder hole 5. In addition, since it is swingably connected to the large diameter sealing piston 22 fitted in the cylinder hole 5, the cylinder hole 5 will not wear out prematurely due to piston prying force.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional example. 1 is the case body, 2 is! 4 is the cylinder block, 5 is
is the cylinder hole, 6 is the piston, 7 is the cylinder chamber, 8 is the swash plate, 9 is the valve plate, 10 is the hole, 11 is the boat, 2
0 is a support block, 21 is a piston insertion hole, 22 is a sealing piston, and 23 is a connecting piston. Applicant Komatsu Manufacturing Co., Ltd. Representative Patent Attorney Masaaki Yonehara

Claims (1)

[Claims] A shaft 2 is rotatably supported in the case body 1, a piston 6 is fitted into the cylinder hole 5 of the cylinder block 4 which is fitted and connected to the shaft 2, and the piston 6 is swung into the case body 1. A hole 10 in the valve plate 9 is slidable along a freely supported swash plate 8, and the cylinder chamber 7 in the cylinder hole 5 is brought into sliding contact with the cylinder block 4.
In the swash plate type piston pump/motor which communicates with the port 11 of the case body 1, a support block 20 having a piston insertion hole 21 is disposed between the cylinder block 4 and the swash plate 8, and this support block 20 is fitted and connected to the shaft 2, and the piston 6 is
Cylinder hole 5 slidably inserted into piston insertion hole 21
A swash plate type piston pump/motor characterized in that a smaller-diameter connecting piston 23 and a larger-diameter sealing piston 22 fitted into the cylinder hole 5 are pivotally connected.