JPH08240178A - Liquid-operated axial-flow piston pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the required number of parts and shorten a pump length by loosely fitting one end of a main shaft in the hollow inside of the charge pump shaft, interlockingly connecting through a spline and also supporting these both ends by a single and common bearing. SOLUTION: A main shaft 1 receives the rotational force from an engine and drives an axial piston pump rotation body 50. One end of the main shaft 1 is supported by a bearing 6 at the front part of a pump housing 52. The bearing at the intermediate part of the main shaft 1 is abolished and instead of this, the other end of the main shaft 1 is supported by loosely fitting 21 in the hollow inside of the charge pump shaft 12 supported one end by the bearing 14. The rotational force between the main shaft 1 and charge pump shaft 12 is transmitted through the spline 22 of the main shaft 1 and the spline 17 of the charge pump shaft 12 meshed with each other. Furter, the main shaft 1 and charge pump shaft 12 are supported by a single common bearing 23 in the diameter change direction at these connection parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic axial piston pump which operates in a closed fluid circuit and which comprises an axial piston rotating assembly and a charging pump.

[0002]

2. Description of the Related Art The total length of hydraulic equipment has become a more important standard when applied to automobiles, as compared with its width and height. For example, in a small or medium wheeled loader, the internal combustion engine and the hydraulic pump connected to the internal combustion engine in the drive train are mounted vertically or transversely to the longitudinal axis of the motor vehicle (wheeled loader). Have been. This arrangement provides convenient access to the internal combustion engine and hydraulic pump for maintenance services. Such laterally mounted engine assemblies are often
Being located behind the rear axle, it is advantageous for weight balancing with other parts of the vehicle. However, if the length of hydraulic equipment such as a hydraulic pump attached to the engine is long, the width of the automobile is excessively increased. Therefore, minimizing the length of hydraulic equipment is a very important factor.

Also, in the case of a structure in which two or three pumps are connected in series instead of the split gear box in which each pump must be individually mounted, the total length of each pump should be as short as possible. Is desirable.

[0004]

Accordingly, it is a primary object of the present invention to provide an axial piston pump having a reduced overall length. Another object of the invention is to simplify the pump assembly, in particular by reducing the number of parts required. It is yet another object of the present invention to provide an axial piston pump with low manufacturing cost and a drive train incorporating the same. Still another object of the present invention is to provide an axial flow piston pump with high operational reliability and a drive system incorporating the same.

[0005]

SUMMARY OF THE INVENTION The present invention provides an axial piston pump having a reduced length for use in a closed fluid circuit hydraulic transmission having an axial piston rotating assembly within a pump housing. provide. The axial piston rotating assembly extends through its center, projects into the end cap of the axial piston pump, extends further into the charging pump, and is connected to the charging pump shaft. have. The main shaft and the charging pump shaft are supported radially at only three points using only three bearings. A first bearing supported within the pump housing supports the spindle near its front end. The second bearing supports the charging pump shaft at a position close to a rear end opposite to one end connected to the main shaft. The third bearing is disposed at a connection between the main shaft and the charging pump shaft, and supports the connection. Therefore,
The third bearing supports both the rear end of the main shaft and the front end of the charging pump shaft.

This three-bearing configuration is possible regardless of whether the charging pump shaft is fitted on the outer peripheral surface of the main shaft, regardless of whether it is inserted into the hollow main shaft. The main shaft and the charging pump shaft can be connected by various means such as a spline so as to transmit torque.

[0007]

1 and 2 show a conventional axial flow piston pump for a closed fluid circuit having auxiliary pads for mounting a second pump or other equipment. In FIG. 1, a main shaft 1 receives rotational power from an engine (not shown) and drives an axial piston rotating assembly 50. The axial-flow piston rotating assembly 50 includes a cylinder block 2, a plurality of pistons 3, a slide metal 4, and a slide metal holding member 5, in addition to a main shaft (also simply referred to as “shaft”) 1.
The shaft 1 has a ball bearing or roller bearing 6 located at the front of the pump housing 52 at one end thereof. Bearing 6
Are fixed by a retaining ring 54 and a shoulder 56 formed on the shaft 1 so as not to move axially with respect to the shaft 1.

Another movable bearing 7 mounted in an end cap 8 on the side of the cylinder block 2 opposite to the side on which the bearing 6 is located, supports the other end of the shaft 1. Normally, the movable bearing 7 is a sliding bearing coated with polytetrafluoroethylene (PTFE), a so-called PTFE DU bush, but if desired, a needle bearing may be used. The end cap 8 connects the high pressure ports 9 of the cylinder block 2 to the high pressure ports of the system. The end of the main shaft 1 on the end cap 8 side is shown here to be solid, but may be hollow.

A charging pressure pump 10, a charging check valve and a pressure relief valve, which are essential for a closed fluid circuit, are incorporated in the end cap 8. The charging pressure pump (also simply referred to as "charging pump") 10 is typically a gerotor or gear pump, the primary role of which is to supply make-up fluid to the low pressure side of the fluid circuit of the system. And supplying a fluid for the servo control device 11. The charging pump 10 has the shaft 12 required to center and drive the gerotor or gears of the pump. The shaft 12 of the charging pump 10 is a hollow shaft and has an inner diameter and an outer diameter.
The shaft 12 is supported by two plain bearings 13 and 14 in the radial direction, and is fixed in the axial direction by a shoulder portion 15 formed on the main shaft 1 and a shoulder portion of the charging pump cover 16. Being detained.

The torque between the main shaft 1 and the charging pump shaft 12 is transmitted by a spline 22 of the main shaft 1 and a spline 17 of the charging pump shaft 12 which are meshed with each other.

As a means for attaching a second pump (not shown) to the axial piston pump, that is, the first pump,
A separate mounting pad 18 is attached to the end cap 8. The shaft of the first pump and the shaft of the second pump are connected by a connection shaft 19 so as to be able to transmit rotational power.

FIG. 2 shows a conventional axial piston pump having a reduced overall length. The shortening of the length eliminates the connecting shaft 19 provided in the axial piston pump of FIG. This is achieved by a configuration that is directly driven by the pump shaft 20. In both the axial piston pump of FIG. 1 and the axial piston pump of FIG. 2, the main shaft is supported by four bearings 6, 7, 13, 14.

FIG. 3 shows an axial piston pump according to the invention which makes it possible to considerably reduce the overall length. In the present invention, the sliding bearing of the main shaft 1 (corresponding to the sliding bearing 7 of the conventional axial piston pump of FIGS. 1 and 2) is omitted. The radial bearing of the main shaft 1 is achieved by a play-fitting of the main shaft 1 in a hollow charging pump shaft 12 as indicated at 21. The torque between the main shaft 1 and the charging pump shaft 12 is transmitted by the spline 22 of the main shaft 1 and the spline 17 of the charging pump shaft 12 which are meshed with each other. The main shaft 1 and the charging pump shaft 12 are supported in the radial direction by a single common slide bearing 23 at the site where the two shafts are connected.

FIG. 4 shows an axial piston pump according to another embodiment of the present invention, characterized in that the bearing 23 in the axial piston pump of FIG. 3 is a needle bearing (needle bearing) 23A. Alternatively, the bearing 23 can be a simple bush type bearing.

[0015]

According to the structure of the present invention, unlike the structure of the conventional axial piston pump as shown in FIGS. 1 and 2 which requires four bearings 6, 7, 13, and 14, Only two bearings 6, 14, 23 are required. Thus, the present invention not only saves the manufacturing cost of the fourth bearing itself, but also the costly formation of the precise inner bore required to receive such a bearing. Eliminate steps as well. According to the configuration of the present invention,
Since it is not necessary to juxtapose the two slide bearings 13 and 14 in the axial direction to support the charging pump shaft 12 as in the conventional axial piston pump, the charging pump 10 is moved closer to the cylinder block 2. Can be arranged. As a result, the total length of the axial piston pump, and therefore,
The length of the drive train using the axial piston pump can be shortened considerably.

In order to connect a plurality of axial piston pumps to form a drive system, SAE "B" for connection,
The length of each axial piston pump with a SAE "C" or SAE "D" adapter can be reduced.
Because the spline 22 of the main shaft 1 and the spline 17 of the charging pump shaft 12 are arranged closer to the cylinder block assembly 50 in the conventional axial piston pump, the shaft 12 of the charging pump is This is because the end cap 8 can be pushed deeper into the end cap 8.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a prior art axial piston pump.

FIG. 2 is a cross-sectional view of another type of prior art axial piston pump.

FIG. 3 is a sectional view of the axial piston pump of the present invention.

FIG. 4 is a sectional view of an axial flow piston pump according to another embodiment of the present invention, wherein the third bearing is a needle bearing.

[Explanation of symbols]

1: Spindle 2: Cylinder block 6: Bearing 8: End cap 10: Charging pump 12: Charging pump shaft 14: Bearing 17, 22: Spline 23: Bearing 23A: Needle bearing 50: Axial piston rotating assembly Solid (cylinder block assembly) 52: Pump housing

Claims (1)

[Claims] 1. An (a) housing; (b) an axial piston rotary assembly and charging pump provided in the housing; (c) a drive for the axial piston rotary assembly in the housing. A liquid of a closed fluid circuit having a connected main shaft and a shaft assembly drivingly connected to the charging pump and including one end of the main shaft coaxially connected to one end of the main shaft. An axial piston pump for a pressure transmission, comprising bearing means having three bearings mounted in the housing for rotatably supporting the shaft assembly,
A first bearing of the bearing means is at the other end of the main shaft opposite the one end connected to the charging pump shaft for rotatably supporting the shaft assembly in the housing. A second bearing of the bearing means is disposed in close proximity and mounted in the housing, and the second bearing of the bearing means is for rotatably supporting the charging pump shaft in the housing. Mounted in the housing at a position close to the other end opposite to the one end connected to the main shaft, and the third bearing of the bearing means is the charging pump shaft. And the main shaft are rotatably supported at the same time, and are mounted in the housing by being radially aligned with the coaxially connected ends of both the charging pump shaft and the main shaft. Axial flow piston pump characterized by.