JPH0312671B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a shoe for a swash plate type compressor, and more particularly to a shoe having holes formed in the sliding surface that slides on the swash plate.

``Prior Art'' A swash plate compressor includes a swash plate rotated by a rotating shaft within a cylinder block and a piston fitted within the cylinder block.
The rotation of the swash plate causes the piston to reciprocate. Conventionally, a shoe and a ball have been used to interlock the swash plate and the piston, and one end surface of the shoe is in sliding contact with the swash plate, and a spherical recess formed on the other end surface of the shoe and the piston. The swash plate and the piston are interlocked by interposing a ball between the ball and the spherical recess formed in the swash plate. Other examples include
It is known that the other end surface is formed into a hemispherical shape, and this hemispherical shape is brought into direct sliding contact with the spherical recess of the piston. A hole with a bottom or a through hole penetrating to the other end surface are also known.

"Problems to be Solved by the Invention" Conventionally known swashes have not caused any particular problems in general use, but as swash plate compressors have become more compressible in recent years, they have become more difficult than before. There is a growing demand for shoes with excellent seizure resistance.

"Means for Solving the Problems" In view of such circumstances, the present invention provides a shoe for a swash plate type compressor in which holes are formed in the sliding surface that slides on the swash plate. A convex surface between the inner periphery of the sliding surface on the hole side and the outer periphery of the sliding surface consists of a top surface and a surface that is lower than the top and smoothly continues on both sides of the top. It is formed into a curved surface, and the apex of the convex curved surface is set at approximately the center in the radial direction between the inner circumference and the outer circumference of the sliding surface or inside thereof.

"Operation" According to this configuration, when the shuttle moves relative to the swash plate, the lubricating oil is brought into sliding contact by the wedge effect created by the gap between the sliding surface and the swash plate on the forward side in the direction of movement from the top. It can be well introduced between the surface and the swash plate to generate a high positive oil film pressure.
Negative pressure is generated in the gap between the sliding surface and the swash plate on the rear side in the direction of travel from the top.
The negative pressure is maintained by keeping the negative pressure generation area small by setting the apex to a position that almost coincides with the center in the radial direction or inside it, and that the negative pressure is maintained even at the maximum. Since the pressure is only 1 atm, it can be much smaller than the positive oil film pressure mentioned above, and therefore the lubrication conditions between the above-mentioned shuttle and the swash plate can be improved to improve seizure resistance. You will be able to aim for it.

"Example" The present invention will be described below with reference to the illustrated example.
In FIG. 1, the shoe 1 is formed into a hemispherical shape as a whole, and the sliding surface 2 of the bottom end surface is connected to the swash plate 3.
At the same time, a hemispherical sliding surface 4 opposite to the sliding surface 2 is brought into sliding contact with a spherical concave portion of a piston (not shown). A bottomed hole 5 is formed in the center of the sliding surface 2.

The sliding surface 2 between the hole 5 and the outer periphery of the shoe 1 includes a surface of the top 2a, a surface 2b lower than the top that smoothly continues from the top surface toward the hole 5, and a surface 2b lower than the top of the top 2a. The top part 2a of the convex curved surface is in sliding contact between the hole 5 and the outer periphery of the shoe 1. It is set at a position that substantially coincides with the radial center portion 6 of the surface or on the inner side thereof.

The convex curved surface has the same shape in the circumferential direction, so that the top portion 2a comes to be in continuous circular sliding contact with the swash plate 3 in the circumferential direction. The sliding surface 2 and the inner peripheral surface of the hole 5 of the shoe 1, that is, the surface 2b located on one side of the top 2a and the inner peripheral surface of the hole 5 are continuous in a smooth arc, and the top The continuous portion between the surface 2c located on the other side of 2a and the outer circumferential surface of the shoe 1 is also continuous in a smooth circular arc so that no corners are formed.

According to the above configuration, the sliding surface 2 of the shoe 1 and the swash plate 3 come into sliding contact at the top portion 2a, and therefore, as shown in FIG. 1 and the swash plate 3 come into sliding contact at two apexes 2a. When the shoe 1 is moved relative to the swash plate 3 in the direction of the arrow in FIG. Due to the wedge effect, the lubricating oil is effectively introduced between the sliding surface 2 and the swash plate 3, and a high positive oil film pressure is generated.

On the other hand, negative pressure is generated in the gap 9 between the sliding surface 2 and the swash plate 3 on the rear side of the top 2a in the direction of travel, but the top 2a is substantially aligned with the center 6 in the radial direction. The negative pressure generation area is kept small by setting it at or inside the above position, and the negative pressure is 1 atm at maximum, which is usually much smaller than the positive oil film pressure. The entire shoe 1 is able to slide smoothly on the swash plate 1 due to the large oil film pressure.

Furthermore, among the two gaps 7 and 8 between the sliding contact surface 2 and the swash plate 3, which are on the forward side in the traveling direction from each top portion 2a, the oil film pressure is the front side in the traveling direction where the vertical oil supply condition is good. Since the gap 7 on the side becomes larger, it is desirable to form the top portion 2a inside the center portion 6 in the radial direction as much as possible, that is, on the side of the center portion of the shoe 1.

However, the hole 5 of the hole 5 of the top part 2a
If the surface 2b is formed close to the top 2a, the radius of curvature of the surface 2b located between the top 2a and the hole 5 becomes small, and as a result, the top 2a covers the swash plate 3, which in turn impairs the seizure resistance.

FIG. 2 is an explanatory diagram for explaining the innermost position of the top portion 2a, and shows the bottom shape of the shoe 1 with vertical magnification (axial magnification) and lateral magnification (radial magnification).
It is displayed at 100x (vertical magnification: horizontal magnification = 1000:10). In the figure, a line 20 is a line connecting the top 2a of the sliding surface 2, a line 21 is a line drawn parallel to the line 20 and 20 μm away from the line 20 toward the shoe 1, and a line 22 is a line drawn parallel to the top 2a of the sliding surface 2. A line drawn perpendicularly to the line 20 from the intersection 23 of the line 21 and the inner peripheral surface of the hole 5, and a line 24 drawn from the intersection 25 of the lines 20 and 22.
It is a line drawn at an angle of 45 degrees from a point 26 that is a required distance L from the point 26, specifically, 4 μm or more. The hole 5 is in contact with this line 24 and the line 20, and
A circular arc 27 is drawn with a radius of curvature that smoothly continues on the inner circumferential surface, and the point where the circular arc 27 touches the line 20 is the position of the innermost apex 2a.

Next, the effects of the present invention will be explained based on the test results shown in FIG. This test measured the seizure resistance of Si, 14-18wt% Si, 2.5-5wt%
Al alloy swash plate 3 consisting of Cu and balance Al
Then, ordinary steel is treated with boron immersion (Hv1300~1500).
The test was conducted from the state where the shoe 1 coated with a thickness of 10 to 15 μm was brought into sliding contact, and the shoe 1 was pressed against the swash plate 3 under a load of 40 kg, with a lubricating oil that was a mixture of refrigerating machine oil and light oil at a ratio of 1:9 interposed. Start and load 20Kg every required time
The load was measured when the load was increased gradually and seizure occurred. The relative sliding speed between the shoe 1 and the swash plate 3 at this time was 15 m/s.

In FIG. 3, A and B are the shoes according to the present invention, A is the one in which the top part 2a is aligned with the center part 6, and B is the one in which the top part 2a is located inside the center part 6, and the hole 5 and the shoe 1 are aligned. It is formed at a position approximately 1/5 of the distance from the outer peripheral surface.

In addition, C to F indicate comparative materials, and C has a convex sliding surface as in the present invention, but the top portion 2a
is formed outside the central portion 6 at a position approximately 1/4 of the distance between the hole 5 and the outer peripheral surface of the shoe 1.
Further, in D, the entire sliding contact surface is formed into a flat surface, and the continuous part between the sliding contact surface and the hole and the continuous part between the sliding contact surface and the outer circumferential surface are corner parts, and E is in the form of D,
The continuous part between the sliding contact surface and the hole and the continuous part between the sliding contact surface and the outer circumferential surface are continuous in a circular arc. The continuous part of the sliding surface and the continuous part of the outer circumferential surface are made continuous by a circular arc.

As understood from the test results shown in Figure 3,
Good results were obtained for the products A and B of the present invention compared to the comparative materials C to F.

Furthermore, FIG. 4 is a diagram showing test results regarding the innermost position of the top portion 2a, in which changes in seizure resistance were measured when the distance L mentioned above was varied variously. The test conditions at this time were the same as those in FIG.

In Fig. 4, the continuous portion between the sliding surface and the outer peripheral surface of the shoe is formed in advance with a large radius of curvature, and the dimension of the distance L in the continuous portion between the sliding surface and the inner peripheral surface of the hole is varied. The effect on seizure resistance was observed by changing the settings.

As can be understood from the figure, the seizure resistance of the comparative material with a flat sliding surface improves as the distance L increases, but no improvement in seizure resistance is observed from 5 μm. As a result, very high seizure resistance cannot be obtained. On the other hand, in the product of the present invention, by setting the distance L to 4 μm, it is possible to ensure seizure resistance that is at least equivalent to the best seizure resistance of the comparative material, and by increasing the distance L. Therefore, even greater seizure resistance can be obtained.

Although the above embodiment has been described with respect to a hemispherical shoe, it goes without saying that the present invention can be similarly applied to a shoe using a conventional ball.

"Effects of the Invention" As described above, according to the present invention, it is possible to obtain the effect that the seizure resistance of the shoe can be improved compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention and a diagram showing the distribution of hydraulic pressure generated when the shoe 1 moves in the direction of the arrow, and FIG. An explanatory diagram to explain the inner position,
FIGS. 3 and 4 are diagrams showing test results regarding seizure resistance, respectively. 1...Shu, 2...Sliding surface, 2a...Top, 2
b, 2c... surface lower than the top, 3... swash plate,
5... Hole, 6... Radial center part.

Claims (1)

[Scope of Claims] 1. In a swash plate type compressor shoe in which a hole is formed in the sliding surface that slides on the swash plate, the sliding surface that slides on the swash plate is located on the hole side of the sliding surface. A convex curved surface consisting of a top surface and a lower surface than the top smoothly continuous on both sides of the top is formed between the inner circumference and the outer circumference of the A shaft for a swash plate type compressor, characterized in that the shaft is set approximately at the center in the radial direction between the inner peripheral part and the outer peripheral part of the sliding surface or inside thereof. 2. The swash plate type compressor shoe according to claim 1, wherein the convex curved surface and the inner circumferential surface of the hole are continuous in a smooth circular arc. 3. The shoe for a swash plate compressor according to claim 1, wherein the convex curved surface and the outer peripheral surface of the shoe are continuous in a smooth circular arc.