JPH06129366A - Vane pump - Google Patents

Abstract

PURPOSE:To lessen increment of the side clearance formed between slits and vanes provided in the rotor of a vane pump. CONSTITUTION:A rotor 3 made of aluminum alloy rotating in a ring 1 is provided with a number of slits 4 stretching radially, and each vane 5 held movably in slit in the radial direction is made of a high carbon cromium steel for bearing, wherein the coefficient of linear expansion of the material for the rotor 3 should be close to that of the material for the vanes 5, and thereby increment of the side clearance can be lessened even when the temp. has risen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vane pump, and more particularly to a vane pump which reduces side clearance between a slit of a rotor and a vane incorporated in the slit.

[0002]

2. Description of the Related Art FIG. 1 shows a general structure of a vane pump. A rotor 3 is rotatably housed in an elliptical hole 2 of a ring 1 whose both end surfaces are closed by bushings, and the outer peripheral surface of the rotor 3 is accommodated in the rotor 3. By providing a large number of slits 4 which are opened in a radial arrangement, a plate-shaped vane 5 is incorporated in each slit 4 so as to be slidable in the radial direction, and the vane 5 moves in and out as the drive shaft 6 and the rotor 3 rotate. A pump action is provided for sending fluid from the suction port 7 to the discharge port 8.

In the above vane pump, in order to increase the mechanical efficiency, the relationship between the slit of the rotor and the vane incorporated in this slit is managed so that the side clearance is in a narrow region.

Although some rotors are made of cast iron, most of them are made by die-casting aluminum. On the other hand, the material of the vane 5 is made to have high hardness because wear resistance is important. The mainstream is adoption of high speed tool steel (SKH).

In the above operating state of the vane pump, the temperature of the pump itself rises. Therefore, if there is a difference in the linear expansion coefficient of the forming material of the rotor 3 and the vane 5, the slit 4 and the vane 5 of the rotor 3 will be different. The side clearance between them becomes large and the mechanical efficiency decreases.

Further, the vane 5 in the vane pump is
The tip surface slides with the inner diameter of the ring 1, and the slit 4
The both surfaces held at 1 have slipped with the rotor 3, so that each of the above surfaces becomes a slip surface and seizure resistance is required.

[0007]

By the way, the linear expansion coefficient of the aluminum die cast used to form the rotor 3 is
In contrast to 2.1 × 10 ⁻⁵ , the linear expansion coefficient of the conventional vane forming material SKH material is about 0.93 × 10 ⁻⁵ , and the linear expansion coefficient of the rotor forming material and the vane forming material is Is large, and as a result, the side clearance between the rotor slit and the vane increases as the temperature rises.
There is a problem that mechanical efficiency is reduced.

The sliding surface of the conventional vane is
Since it has been finished to a smooth polished surface, the oil film formation rate on the sliding surface is poor, and when the amount of lubricating oil is small, there is a problem that seizure occurs due to poor lubrication and durability is reduced.

In order to solve the above problems, the present invention can reduce the increase in the side clearance even when the temperature rises, and can sufficiently form the oil film on the sliding surface of the vane, thereby improving lubrication. It is an object of the present invention to provide a vane pump capable of improving the durability, preventing the occurrence of seizure, and improving the durability.

[0010]

In order to solve the above problems, the first invention adopts a structure in which vanes used in a vane pump are made of high carbon chromium bearing steel.

In the second invention, innumerable minute depressions are randomly provided on the surface of the vane, the average area of the minute depressions is 35 to 150 μm ² , and the ratio of the minute depressions to the surface is 10 to 40%. The configuration is adopted.

A third aspect of the present invention is the same as the first or second aspect of the invention, in which the rotor of the vane pump is made of an aluminum alloy.

[0013]

Since the vane forming material is the high carbon chromium bearing steel, the linear expansion coefficients of the rotor forming material and the vane forming material are close to each other, and the increase amount of the side clearance can be reduced even when the temperature rises.

In addition, innumerable minute depressions are randomly provided on the surface of the vane used for the vane pump, and the average area of the minute depressions is 35 to 150 μm ² , and the ratio of the minute depressions to the surface is 10 to 40%. Further, the oil film formation rate on the sliding surface of the vane is improved, the temperature rise is prevented, seizure is prevented, and the service life is extended.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

The basic structure of the vane pump is as shown in FIG. 1, the rotor 3 is made of aluminum alloy and is formed by aluminum die casting, and the vane 5 is made of high carbon chromium bearing steel (SUJ2). ing.

The linear expansion coefficient of aluminum die cast is 2.
To 1 × 10 is to ^-5, the linear expansion coefficient of the SUJ2 material used as the material of the vane 5 is about 1.1 × 10 ^-5, about as compared with the conventional SKH material is vane material 20
% The coefficient of linear expansion is large, which means that the linear expansion coefficient of the forming material of the rotor 3 and the forming material of the vanes 5 are close to each other, and the amount of increase in the side clearance between the slit 4 and the vane 5 of the rotor 3 at the time of temperature rise. Can be reduced.

In the vane pump, the vane 5 held by the slit 4 of the rotor 3 has a tip end surface that is a slip surface for the ring 1, both surfaces are slip surfaces for the rotor 3, and both ends are slip surfaces for the bushings. The SUJ2 material used in the past has excellent wear resistance, but in order to further improve wear resistance and durability, these slip surfaces on the vane 5 are treated with special barrel polishing as shown in Fig. 2 to create numerous indentations. The surface is a minute rough surface a randomly formed.

FIG. 3 shows a cross-sectional roughness shape of the minute rough surface a. As shown in FIG. 3, a concave surface is formed on a flat surface so that a convex surface is not formed on the flat surface.

The average area of the fine depressions of the fine rough surface a is 35 to 150 μm ² , and the ratio of the depressions to the surface is 10 to 40%.

The surface roughness of the micro-rough surface a is Rma on average.
x0.6 to 2.5 μm, and the surface roughness parameter SK value is SK value ≦ −1.6.

The parameter SK value refers to the degree of distortion (SKEWNESS) of the distribution curve of the surface roughness, and the SK value is 0 for the symmetrical distribution such as the Gaussian distribution, but the parameter SK value is the The shape and distribution are in a range that is advantageous for oil film formation, and the depressions serve as oil reservoirs in sliding contact, and serve to supply oil to the contact portions.

Next, a comparative test was conducted by giving the vane of the present invention having a large PV value (P: contact surface pressure, V: sliding speed) due to sliding contact to the surface of the vane having a different area ratio of the fine depressions.

The sliding frictional resistance of the sliding portion is obtained as the pump rotation torque. The anti-seizure performance was compared by the time until seizure with a small amount of lubrication. The results are shown in FIGS. 4A and 4B.

As is clear from the results shown in the figure, the area ratio of the depressions on the surface is 10% or more, the sliding friction resistance,
It has an effect on seizure resistance.

[0026]

As described above, according to the present invention, since it has the above-mentioned structure, the following effects can be obtained.

(I) Since the vanes of the vane pump are formed of high carbon chromium bearing steel, the linear expansion coefficient of the aluminum alloy forming the rotor and the vane forming material are close to each other, and the temperature between the slits of the rotor and the vanes increases when the temperature rises. The increase amount of the side clearance can be reduced, and the mechanical efficiency of the vane pump can be prevented from lowering.

(II) High carbon chrome bearing steel has excellent wear resistance and can improve the durability of the vane.

(III) An infinite number of minute depressions were randomly provided on the sliding surface of the vane used for the vane pump, and the average area of the minute depressions was 35 to 150 μm ² , and the proportion of the minute depressions on the surface was 10 to 40%. Therefore, the random minute rough surface easily forms an oil film, and since the minute depressions serve as an oil reservoir, the oil film can be reliably formed on the sliding surface of the vane, and the torque when the vane pump rotates can be reduced.

(IV) Since the oil film on the sliding surface can be formed efficiently and surely, the seizure resistance of the vane can be improved.

(V) Since the oil film on the slip surface can be reliably formed, the increase in the temperature of the vane can be reduced.

(VI) The durability of the vane can be further improved by reducing the torque and improving the seizure resistance.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the structure of a vane pump.

FIG. 2 is a perspective view of a vane.

FIG. 3 is a cross-sectional view showing a surface roughness state of a slip surface of a vane.

4A and 4B are graphs showing the measurement results of the area ratio of minute depressions, pump rotation torque, and seizure resistance.

[Explanation of symbols]

 1 ring 3 rotor 4 slit 5 vane a micro rough surface

Claims (3)

[Claims] 1. A vane pump in which the vanes used in the vane pump are formed of high carbon chromium bearing steel. 2. An infinite number of minute depressions are randomly provided on the surface of the vane, and the average area of the minute depressions is 35 to 150.
μm ² , the percentage of the surface of the micro depression is 10 to 40
The vane pump according to claim 1, wherein the percentage is%. 3. The vane pump according to claim 1, wherein the rotor of the vane pump is made of an aluminum alloy.