JPH0510250A - Hydraulic pump - Google Patents

Abstract

PURPOSE:To prevent the internal pressure in a case from rising to regulated pressure or higher. CONSTITUTION:The inside 16 of a case 1 and a suction port 9 are allowed to communicate through a communication hole 18 having a check valve 17, and a portion of the pressurized oil inside the case 1 is supplied into the suction port 9, and the increase of the internal pressure in the case over a prescribed pressure is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic pump.

[0002]

2. Description of the Related Art As a hydraulic pump, a cylinder block is rotatably provided with a shaft in a case, a piston is inserted into a cylinder hole of the cylinder block to form a cylinder chamber, and a piston shoe provided on the piston is slanted. It is known to hold slidably along the plate, and to communicate the cylinder chamber alternately from the port of the valve plate to the suction port and the discharge port so that oil is sucked into the cylinder chamber from the suction port and discharged from the discharge port. ing. In such a hydraulic pump, high-pressure oil leaks into the case from between the cylinder hole and the piston, so that the case is communicated with the tank and the pressure oil leaking into the case flows out to the tank and the shaft of the case An oil seal is provided between the bearing hole and the shaft to prevent the pressure oil in the case from flowing out from the shaft bearing portion.

[0003]

In such a hydraulic pump, the internal pressure of the case increases when the temperature is low or when the amount of high-pressure oil leakage increases due to wear deterioration of parts such as cylinder holes and pistons. However, the durability of the oil seal may deteriorate, and the oil may flow out from the shaft support portion.

Therefore, an object of the present invention is to provide a hydraulic pump which can solve the above-mentioned problems.

[0005]

Means for Solving the Problems A case in which the inside of the case and the suction port are communicated with each other by a communication passage having a check valve.

[0006]

[Operation] Part of the pressure oil inside the case is supplied to the suction port from the communication passage, preventing the internal pressure of the case from rising above the specified pressure.

[0007]

[Example] As shown in FIG. 1, a cylinder block 2 is rotatably supported together with a shaft 3 in a case 1,
A piston 5 is fitted into a cylinder hole 4 of the cylinder block 2 to form a cylinder chamber 6, and the cylinder chamber 6 is alternately communicated from a port 8 of a valve plate 7 to a suction port 9 and a discharge port 10 to form a piston 5 When the cylinder shoe 2 is slidably held along the swash plate 12 and the cylinder block 2 is rotated together with the shaft 3, the piston 5 is slid and oil is sucked into the cylinder chamber 6 through the suction port 9. Discharge port 1 by pressurizing oil in cylinder chamber 6
When the shaft 3 is discharged from 0, the shaft 3 is rotatably supported by a bearing 14 in a shaft supporting hole 13 of the case 1 and protrudes out of the case 1. Is provided. The inside 16 of the case 1 and the suction port 9 communicate with each other through a communication hole 18 having a check valve 17,
This check valve 17 is located inside the case 16 from the suction port 9.
Block the flow of pressure oil to.

[0008]

The part of the pressure oil in the inside 16 of the case 1 is supplied to the suction port 9 so that the internal pressure of the case 1 does not rise above the specified pressure, and the oil seal 15 is not a pressure resistant type and is inexpensive. It is possible to improve the durability of the oil seal 15 and prevent the oil seal 15 from flowing out from the shaft support portion.

[Brief description of drawings]

FIG. 1 is a sectional view of a hydraulic pump.

[Explanation of symbols]

1 case, 2 cylinder block, 3 axis, 4 cylinder hole, 5 piston, 6 cylinder chamber, 7 valve plate, 8 port, 9 suction port, 10 discharge port,
11 piston shoe, 12 swash plate, 13 shaft bearing hole,
15 oil seal, 16 inside, 17 check valve,
18 communication holes.

Claims (1)

Claims: 1. A cylinder block 2 is rotatably supported in a case 1 together with a shaft 3, and a piston 5 is inserted into a cylinder hole 4 of the cylinder block 2 to form a cylinder chamber 6. The cylinder chamber 6 is connected to the port 8 of the valve plate 7.
The suction port 9 and the discharge port 10 are alternately communicated with each other, and the piston shoe 11 provided on the piston 5 is slidably held along the swash plate 12, and the shaft support hole 13 of the case 1 is provided.
The oil seal 15 is provided between the shaft 1 and the shaft 3, and the case 1
A hydraulic pump characterized in that the inside 16 of the above is communicated with the suction port 9 through a communication hole 18 provided with a check valve 17.