JPS63212779A - Piston pump or motor - Google Patents

Abstract

PURPOSE:To prevent the generation of rocking of a piston in an inclined shaft type piston pump or motor, by crowning a sleeve in such a manner that an axially central portion only of the sleeve contacts the piston bore. CONSTITUTION:A cylinder block 3 is located in inclined relationship to a torque plate 2, and is formed with a plurality of piston bores 4 arranged at equal intervals. Each piston bore 4 receives a piston 5 through a sleeve 10. An inner circumference 10a of the sleeve 10 is closely fitted with the piston 5, and an outer circumference 10b of the sleeve 10 is formed by crowning a cylindrical surface into an arcuate surface, whereby an axially central portion only of the outer circumference 10b contacts the piston bore 4. When the cylinder block 3 and the torque plate 2 are rotated synchronously, the piston 5 is reciprocated in the sleeve 10 in close contact with the inner circumference 10a, thus obtaining a good sealability. The outer circumference 10b rollingly contacts the piston bore 4 with a contact position varied, and a slippage between center lines of the piston 5 and the piston bore 4 can be smoothly absorbed. Thus, the structure may be made simple and compact.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an oblique shaft type piston pump or motor used in various hydraulic equipment fields.

[Prior Art] As shown in FIG. 4, a diagonal shaft type piston pump/motor has a cylinder block 3 inclined with respect to a torque plate 2 connected to an input/output shaft 1. The torque plate 2 has a central mechanism that pivots each piston 5 fitted into the piston bore 4 of the torque plate 2 .

However, the operating characteristic of this oblique shaft type is that the center line of the piston 5 and the piston bore 4 in which the piston 5 is fitted cannot completely match, and the center line of the piston 5 does not coincide with the rotational phase of the cylinder block 3. The piston may constantly oscillate relative to the center line of the piston bore 4 depending on the movement of the piston.

This will be explained in more detail with reference to FIG.

The torque plate 2 is connected to the input/output shaft 1 along with the axes X and X.

On the other hand, the cylinder block 3 is rotated about axes A, A, which form a certain inclination angle θ with the cylinder block 3. Then, at the intersection 01 of both axes, planes Y, Y1 are set up perpendicular to the axes X, X, and at the intersection 02 of these planes Y, Y and the axis X2, X2 parallel to the axes The tip of each piston 5 is pivotally supported on the torque plate 2. Then, when the positional relationship shown in the figure exists, the intersection of the center line A2A2 of the piston bore 4 and the planes Y, Y is located at a distance of R/cos θ from the point 01, and exactly coincides with the position of the piston pivot point 02. It turns out. However, if we focus on the phase rotated 90 degrees from the position in the figure, we can see that the center line A2A2 of the piston bore 4 and the plane Y
1Y, is equal to the intersection of the perpendicular line drawn from point 01 to line A2A2, and is shifted from the piston pivot point 02. In other words, the center line A2A2 of the piston bore 4 and the plane Y.

The intersection with Yl is around point 01 with minor axis R1 major axis R/CO
In contrast, the piston pivot point 02 moves on a circumference of a radius R/cos θ circumscribing the piston pivot point 02, whereas the piston pivot point 02 moves on the circumference of the radius R/cos θ. Therefore, in this pump/motor, the center line of the piston 5 is the center line A2 of the cylinder bore 4.
With respect to A2, it is inevitable that the piston oscillates by the amplitude R (1/cos θ-1) every half rotation (hereinafter, this is referred to as a piston oscillation phenomenon).

Therefore, in oblique shaft type piston pumps/motors, the following two methods have been adopted as a measure against this piston rocking phenomenon.

One method is to use a connecting rod as shown in FIG. That is, in this method, the piston 5A
is pivoted to the torque plate 2 via the connecting rod 7 which is swingably connected to the piston 5A, thereby suppressing the piston swinging phenomenon.
The center lines of the piston bore 4 and the piston 5A can be aligned without any problem.

Another method utilizes a tapered piston as shown in FIG. That is, in this system, the tip of the piston 5B is directly supported on the torque plate 2, and the outer periphery of the piston 5B is formed with a tapered shape to avoid interference with the piston bore 4. Piston ring for high pressure seal at the moving base end 8.
8 is fitted. Note that in FIGS. 5 and 6, for convenience, a synchronous rotation mechanism (universal joint) between the cylinder block 3 and the torque plate 2 is not shown.

[Problems to be Solved by the Invention] However, with any of the above measures, there are the following problems.

First, in the case of the connecting rod method, the number of parts increases and becomes more complicated, leading to cost savings, and additional space is required in the axial direction due to the connection of the connecting rods, which reduces the size of the pump/motor. There are some inconveniences that are a big hindrance.

In addition, in the case of the tapered piston system, the piston ring on the proximal end is subject to not only the reciprocating movement of the piston but also the relative tilting movement of the piston with respect to the piston bore, which causes severe sliding wear and shortens the service life. There is.

In view of the above-mentioned problems in the countermeasures against the piston oscillation phenomenon adopted in oblique shaft type piston pumps/motors, the present invention provides a compact pump/motor with a simple structure that can replace the conventional means. This was done with the aim of realizing a new mechanism that would be effective in reducing heat loss and expected to have a long life.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a diagonal shaft type piston pump/motor by inserting a sleeve into the piston bore of the cylinder block and fitting the piston. It consists of

The inner periphery of the sleeve is formed into a cylindrical surface into which the piston fits concentrically with the sleeve, and the outer periphery of the sleeve is formed into a crown (with a crown) in which the sleeve is inscribed in the piston bore only at the central portion in the axial direction. (middle and high school).

[Effects] If the piston is fitted into the piston bore by inserting such a sleeve, the piston slides on a concentric cylindrical surface formed on the inner circumference of the sleeve, ensuring good sealing performance on the outer circumference of the piston. be done. In response to the piston rocking phenomenon, the crown on the outer periphery is in rolling contact with the piston bore, and the sleeve can tilt together with the piston in a direction perpendicular to the center line of the piston bore. It is possible to smoothly absorb the deviation of the center line.

[Example code] An example will be described below.

FIG. 1 shows the main parts of the oblique shaft type piston pump/motor according to the present invention. In the figure, 2 is a torque plate, and 3 is a cylinder block arranged at an angle to the torque plate 2. It is.

The torque plate 2 has its axial center connected to an input/output shaft (not shown) from the right side, while the rear end surface of the cylinder block 3 is attached to the inner surface of the rear cover 9 for sliding engagement. Furthermore, this pump/motor is manufactured by patent application No. 59-389.
As already proposed in No. 60, the inclination angle θ of the cylinder block 3 is set to a small inclination angle of about 10″.

The cylinder block 3 has a plurality of piston bores 4 opened at equal angular intervals parallel to its axis, and a piston 5 is fitted into each piston bore 4 by inserting a sleeve 10 therein. There is. The sleeve 10 has an inner circumference 10a formed into a cylindrical surface into which the outer circumference of the piston 5 fits without a gap, and the piston 5 reciprocates and slides on this inner circumference 10a. On the other hand, the outer periphery 10b of the sleeve 10 is formed into an arcuate surface by crowning the cylindrical surface, and is formed into a crown (arc-shaped curved surface) inscribed in the piston bore 4 only at its axial center. The sleeve 1-0 is formed to have the same axial length as the piston bore 4, and has an open flange 10c provided at its proximal end in contact with and supported by the bottom wall 4a of the piston bore 4.

Piston bore 4 with sleeve 1o inserted in this way
At the same time, each piston 5 has a spherical end 5a formed at its tip on the torque plate 2,
It fits into the provided spherical seat 2a and is directly pivotally connected to the torque plate 2. In addition, 11 in the figure
1 is a piston retainer that holds the spherical end 5a of the piston 5 in close contact with the torque plate 2, and 12 indicates a pressure pocket provided between the spherical end 5a of the piston 5 and the spherical seat 2a of the torque plate 2. Note that operating pressure is introduced into this pressure pocket 12 from the inner end of the piston through a liquid passage passed through the axis of the piston 5.

As described above, in the structure in which the sleeve 1o is inserted into the piston bore 4, the piston 5 reciprocates and slides on the concentric cylindrical surface formed on the inner periphery 10a of the sleeve and has a long fitting margin. Compared to the piston system, good sealing performance can be obtained on the outer periphery of the piston, and there is no abnormal wear unlike in the case of seals with piston rings.

In response to the piston rocking phenomenon, the sleeve 1o that concentrically holds the piston 5 rolls into contact with the piston bore 4 while changing the position of the crown formed on its outer periphery 10b, as shown in FIG. It freely tilts within the piston bore 4 in a direction perpendicular to its center line. That is, by changing the posture of the sleeve 10, it is possible to easily absorb the deviation of the center line between the piston 5 and the piston bore 4. In this mechanism, it is sufficient to compactly insert the simple-shaped sleeve 1o into the piston bore 4, so compared to the connecting rod method, the structure does not become complicated, and in particular, unnecessary stroke in the axial direction is avoided. This is not necessary, and the pump/motor as a whole is advantageous for downsizing.

Furthermore, by combining the sleeve 10 and the piston 5, the rotations of the cylinder block 3 and torque plate 2 are synchronized. The phase shift between the torque plate 2 and the cylinder block 3 during this synchronous rotation is determined by the amount of crowning of the outer circumference 10b of the sleeve, so the amount of crowning is determined by the amplitude R (1/
It is desirable that the amount is sufficient to absorb cos θ-1). However, when the inclination angle θ is 10', R
(1/cos θ-1) −0,015R, so it is not as difficult as the one on the left.

Note that the crown formed on the outer periphery 10b of the sleeve 10 also includes a modified example in which conical tapers are formed on both sides as shown in FIG.

[Effects of the Invention] As described above, in the oblique shaft type piston pump/motor of the present invention, by inserting the sleeve into the piston bore and fitting the piston, it is possible to overcome the conventional means as a countermeasure mechanism for the piston rocking phenomenon. The present invention provides a device that can solve the drawbacks of the above and achieve reliable sealing performance and a compact and simple structure.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a main part of an oblique shaft type piston pump/motor showing one embodiment of the present invention, and FIG. 2 is a partial cross-sectional view showing its operation. FIG. 3 is a longitudinal sectional view showing a modification of the sleeve according to the present invention. FIG. 4 is an explanatory diagram used to explain the piston rocking phenomenon in the oblique shaft type piston pump/motor. 5 and 6 are partial sectional views of the main parts of a pump/motor showing a conventional example. 1... Input/output shaft 2... Torque plate 3
...Cylinder block 4...Piston bore 5...
・Piston 10...Sleeve

Claims (1)

[Claims] A piston pump/motor having an oblique shaft in which a piston is fitted by inserting a sleeve into a piston bore of a cylinder block, the inner periphery of the sleeve being a cylinder into which the piston is fitted concentrically with the sleeve. A piston pump or motor, characterized in that the outer periphery of the sleeve is formed into a crown that is inscribed in the piston bore only at the central portion of the sleeve in the axial direction.