Hydraulic pump and detachable servo unit

Patent metadata

Field	Value
Publication number	US-10570893-B2
Application number	US-201615165976-A
Country	US
Kind code	B2
Filing date	May 26, 2016
Priority date	May 29, 2015
Publication date	Feb 25, 2020
Grant date	Feb 25, 2020

Abstract

A housing of a hydraulic pump is configured to have a servo unit detachably attached thereto so as to control tilt direction and angle of its movable swash plate. A port block is formed therein with a pair of main ports and, and a pair of main fluid passages and fluidly connecting respective main ports and to cylinders in its cylinder block. Main ports are used to have respective external pipes connected thereto so as to fluidly connect the hydraulic pump to a hydraulic motor disposed outside of the hydraulic pump, thereby constituting a hydrostatic transmission.

First claim

What is claimed is:

1. A hydraulic pump, comprising:
a drive shaft that receives power from a power source;
a housing journaling the drive shaft;
a port block assembled with the housing;
a cylinder block slidably and rotatably attached to the port block and disposed in the housing;
a plurality of plungers fitted into respective cylinders formed in the cylinder block so as to reciprocally slide parallel to the drive shaft; and
a movable swash plate rotatably supported by the housing and abuts against the plurality of plungers,
wherein the housing is configured to selectively receive a servo unit for adjusting a tilt direction and a tilt angle of the movable swash plate, such that the servo unit is configured to selectively attach to and selectively detach from the housing,
wherein the port block includes a pair of externally open ports which are configured to be fluidly connected via respective external pipes to a hydraulic motor disposed separately from the hydraulic pump,
wherein the port block includes a pair of main fluid passages connecting the respective externally open ports to the cylinders in the cylinder block,
wherein the port block includes a fluid-charge passage for supplying hydraulic fluid to the pair of main fluid passages,
wherein the port block has a plane surface to which the cylinder block is attached,
wherein the plane surface is perpendicular to the drive shaft,
wherein the pair of main fluid passages include parallel portions, which are parallel to each other and to the plane surface,
wherein a pair of charge check valves are disposed on the parallel portions of the pair of main fluid passages, respectively,
wherein the port block is provided therethrough between one side surface and another side surface thereof opposite each other with the fluid-charge passage fluidly connected to the pair of charge check valves,
wherein an open end of the fluid-charge passage at the one side surface of the port block serves as a port for receiving hydraulic fluid from an outside of the hydraulic pump, and
wherein another open end of the fluid-charge passage at the other side surface of the port block serves as a servo port for supplying hydraulic fluid to the servo unit attached to the housing.

2. The hydraulic pump according to claim 1 ,
wherein the port block is provided with a charge relief valve for regulating a hydraulic pressure in the fluid-charge passage, and
wherein the charge relief valve is extended from the port block to an inside of the housing.

3. The hydraulic pump according to claim 2 ,
wherein the charge relief valve and the fluid-charge passage are disposed in a portion of the port block between the pair of charge check valves, and
wherein the charge relief valve is extended parallel to the drive shaft.

4. The hydraulic pump according to claim 1 , further comprising:
a pair of supporters by which the movable swash plate is tiltably supported at respective opposite side portions thereof; and
a sensor for detecting a tilt angle of the movable swash plate,
wherein the servo unit is fixed to one of the supporters, and
wherein the sensor is fixed to the other of the supporters.

5. The hydraulic pump according to claim 1 ,
wherein the hydraulic pump is provided with at least one external pump driven by the drive shaft, and is configured so that fluid delivered from the at least one external pump is supplied to the servo unit, and
wherein a filter is assembled with the hydraulic pump so as to filter the fluid delivered from the at least one external pump before the fluid enters the servo unit.

6. A hydraulic pump, comprising:
a drive shaft that receives power from a power source;
a housing journaling the drive shaft;
a port block assembled with the housing;
a cylinder block slidably and rotatably attached to the port block and disposed in the housing;
a plurality of plungers fitted into respective cylinders formed in the cylinder block so as to reciprocally slide parallel to the drive shaft; and
a movable swash plate rotatably supported by the housing and abuts against the plurality of plungers,
wherein the housing is configured so that a servo unit for adjusting a tilt direction and a tilt angle of the movable swash plate is detachably attachable to the housing,
wherein the port block includes a pair of externally open ports which are configured to be fluidly connected via respective external pipes to a hydraulic motor disposed separately from the hydraulic pump,
wherein the port block includes a pair of main fluid passages connecting the respective externally open ports to the cylinders in the cylinder block,
wherein the port block includes a fluid-charge passage for supplying hydraulic fluid to the pair of main fluid passages,
wherein the port block is provided with a charge relief valve for regulating a hydraulic pressure in the fluid-charge passage,
wherein the charge relief valve is extended from the port block to an inside of the housing,
wherein the port block has a plane surface to which the cylinder block is attached,
wherein the plane surface is perpendicular to the drive shaft,
wherein the pair of main fluid passages include parallel portions, which are parallel to each other and to the plane surface,
wherein a pair of charge check valves are disposed on the parallel portions of the pair of main fluid passages, respectively,
wherein the charge relief valve and the fluid-charge passage are disposed in a portion of the port block between the pair of charge check valves, and
wherein the charge relief valve is extended parallel to the drive shaft.

7. The hydraulic pump according to claim 6 ,
wherein the port block is provided therethrough between one side surface and another side surface thereof opposite each other with the fluid-charge passage crossing the pair of charge check valves,
wherein an open end of the fluid-charge passage at the one side surface of the port block serves as a gauge port for receiving hydraulic fluid from an outside of the hydraulic pump, and
wherein another open end of the fluid-charge passage at the other side surface of the port block serves as a servo port for supplying hydraulic fluid to the servo unit attached to the housing.

8. A hydraulic pump system, comprising:
a hydraulic pump comprising:
a drive shaft that receives power from a power source;
a housing journaling the drive shaft;
a port block assembled with the housing;
a cylinder block slidably and rotatably attached to the port block and disposed in the housing;
a plurality of plungers fitted into respective cylinders formed in the cylinder block so as to reciprocally slide parallel to the drive shaft; and
a movable swash plate rotatably supported by the housing and abuts against the plurality of plungers; and

a servo unit for adjusting a tilt direction and a tilt angle of the movable swash plate,
wherein the housing is configured to selectively receive the servo unit, such that the servo unit is configured to selectively attach to and selectively detach from the housing,
wherein the port block includes a pair of externally open ports which are configured to be fluidly connected via respective external pipes to a hydraulic motor disposed separately from the hydraulic pump,
wherein the port block includes a pair of main fluid passages connecting the respective externally open ports to the cylinders in the cylinder block,
wherein the port block includes a fluid-charge passage for supplying hydraulic fluid to the pair of main fluid passages,
wherein the port block is provided with a charge relief valve for regulating a hydraulic pressure in the fluid-charge passage,
wherein the charge relief valve is extended from the port block to an inside of the hous

Assignees

• Kanzaki Kokyukoki Mfg Co Ltd

Inventors

• Yasuda Toshifumi
• Murashima Daisuke
• Ota Takehiro

Classifications

• F16H39/04

  with liquid motor and pump combined in one unit · CPC title

• F04B1/324 Primary

  by changing the inclination of the swash plate · CPC title

• F04B53/00 Primary

  Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00 · CPC title

• F04B53/22

  Arrangements for enabling ready assembly or disassembly · CPC title

• F04B53/10

  Valves; Arrangement of valves · CPC title