JPS6128768A - Cylinder groove of piston type fluid machine - Google Patents

Abstract

PURPOSE:To improve seizure resistance over all operating ranges by forming grooves in the centrifugal force-applied direction on part of the inner periphery of a cylinder where a piston is slided. CONSTITUTION:When a piston 3 is coupled with a cylinder 4 at its top dead point, the pressure oil with the same pressure as that of the cylinder 4 is fed into grooves 5b to press the piston 3, thereby seizure due to a centrifugal force can be prevented. When the piston 3 is coupled with the cylinder 4 at the middle between the top dead point and the bottom dead point, sufficient bending moment M against a tangential force W is applied, and seizure due to one-sided contact can be prevented. Furthermore, when the piston is at its bottom dead point, no tangential force or no centrifugal force is applied because of a discharge completion storke.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a piston-type fluid machine such as a pump motor or a compressor, and particularly to a piston-type fluid machine suitable for preventing seizure between a cylinder and a piston. It is.

[Conventional technology]

FIG. 6 shows a conventionally commonly used piston type fluid machine.

The main shaft 1 is slidably fitted into the center of the cylinder barrel 2 via a spline 10. A plurality of cylinders 4 are bored on the same circumference of the cylinder barrel 2, and the cylinders 4
Pistons 5 are each slidably inserted therein. A bushing 5 is interposed between the cylinder 4 and the piston 3 to prevent seizure. The bushing 5 is made of a material that is resistant to seizure, such as copper alloy, and is cast and bonded to the cylinder 4.
Fitted by press-fitting, etc. As shown in FIG. 7, a plurality of (FIJ) circumferential grooves 5a are bored near the end of the bush 5 on the insertion side of the piston 5. The swash plate box 7 is provided at an angle to the main shaft 1, and a swash plate 8 is provided on the inclined surface.
is provided. A boat plate 9 is fixed to the main body side, and a suction/discharge bow 9g communicating with the main body side is formed in the port plate 9. . This suction and discharge bow)
9a are formed at positions communicating with the cylinder 4, respectively.

With the above configuration, the main shaft 1 is rotated, suction and compression force acts within the cylinder 4, and the medium (fluid such as oil) is sucked into the cylinder 4 from the suction and discharge bow 9a and is discharged. Ru.

As shown in FIG. 7, during operation, a lateral force W acts on the center Os of the tip of the piston 3 as a reaction force from the swash plate 8 as shown.

Due to the action of this lateral force W, a bending moment acts on the piston 3, causing it to tilt as shown. Therefore, an inclined gap is formed between the inner surface of the cylinder 4, or more precisely, the inner surface of the bush 5 and the piston 3. For this reason, the pressure distribution acting within this inclined gap does not become a constant pressure as shown in FIG. In other words, if the circumferential groove 5a is not formed in the bush 5, the pressure distribution will be as shown by dots, and the side in the direction of centrifugal force action of the cylinder 4 (the side where the gap narrows toward the open side of the cylinder 4) is The upper part of the figure (shown in A) has a convex curve distribution as shown in K, and the opposite side (the side where the gap widens toward the open forest side of cylinder 4) has a concave curve distribution as shown in the lower part of the figure (shown in B). It becomes a curve.

However, when the circumferential groove 5a is present, the pressure distribution curve becomes as shown by the solid line in the figure, and no pressure distribution occurs in the circumferential groove 5alC.

Due to the pressure in the gap based on the above pressure distribution, a bending moment (M) in the opposite direction to the bending moment direction due to the lateral force W acts, pushing the piston 3 in a direction away from the inner circumferential surface of the bush 5.

From the above, during high-pressure operation when a large lateral force W acts on the piston 3, the presence of the circumferential groove 5a causes the bending moment M
If the piston 6 is small, the piston 6 will hit the bush 5 unevenly, resulting in a disadvantage that seizure damage is likely to occur.

On the other hand, in normal cases, the medium in the cylinder 4 is supplied into the circumferential groove 5a and forms an oil film, etc., so it is more effective in preventing seizure than in the case without the circumferential groove 5a, and during rotation. It also has the advantage of being effective against centrifugal force. Therefore, low pressure, high 1sxv, and. □1. Kaka, hey □□□11 An effective and simple structure was required.

[Problems that Kakemei tries to solve]

The present invention has been made in view of the above circumstances, and its object is to provide a piston-type fluid machine with a simple structure that has seizure resistance over the entire operating range.

[Means for solving problems]

In order to achieve the above object, the present invention utilizes a piston-type fluid machine in which a groove is formed in a part of the inner circumferential surface of a cylinder on which a piston slides in a direction in which centrifugal force is applied.

[For production]

By supplying the medium into the grooves formed only in the direction of centrifugal force on the inner circumferential surface of the cylinder, this prevents seizure due to centrifugal force during high-speed rotation and low-pressure operation. This is to prevent seizure during operation.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

In FIGS. 1 to 5, the same reference numerals as in FIG. 6 indicate the same items or items having the same function.

As shown in FIGS. 1 and 2, a plurality of rows of @5b are formed on the inner peripheral surface of the pusher L5 fitted into the cylinder 4. This groove 5b is formed only in the E direction shown in FIG. 2, that is, the direction in which the centrifugal force acts, and is formed at an appropriate length along the circumferential direction at a position near the piston insertion end of the bushing 5, as shown in FIG. is formed.

In Figure 2, the piston 3 is the cylinder 4! Hm, C, C
The case where both are engaged is exactly at the beginning of discharge, and the direction F in the figure C = middle stroke of discharge. , when the G-direction CS discharge is completed, and the fit is 15<, a large lateral force W acts and uneven contact occurs (see Fig. 7), but the piston speed is zero, so there is no burnout. To prevent sticking, only the influence of centrifugal force caused by the rotation of the cylinder barrel 2 needs to be considered. Pressure oil having the same pressure as the inside of the cylinder 4 is supplied into the groove 5b and presses the piston 3, thereby preventing seizure due to centrifugal force. The groove 5b was formed near the end of the bushing 5 on the insertion side of the piston 6 in consideration of the above-mentioned inclination of the piston A caused by the lateral force W, and the position, size, number, etc. of the groove 5b can be determined as appropriate depending on the capacity of the machine. When something is moving, a relatively high pressure is applied and the piston speed is high. Therefore, one-sided contact of the piston 5 occurs, making it easy to seize.However, since there is no circumferential groove 5a in this part, which is different from the conventional technology, the pressure distribution (dotted line) shown in Fig. 7 acts, and the lateral force W
The tenth song that resists Momen) M acts. Therefore, neither bias force nor centrifugal force acts.

As described above, seizure can be reliably prevented in all ranges of high and low pressure and high speed rotation.

Furthermore, this embodiment is a simple one in which the groove 5b is formed in the bushing 5, and can be implemented easily and at low cost.

4 and 5 show other embodiments.
The figure shows one in which grooves 5C connected in an inclined manner are formed, and Fig. 5 shows a groove in a barbed row A. The grooves 5d are all connected by mutually communicating grooves. In either case, the same effects as in the above embodiment can be achieved.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to improve the seizure resistance over the entire operating range with a simple structure.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the cylinder axis showing the fourth embodiment of the present invention;
The figure is a cross-sectional view of Figure 1 taken along the line ■, Figure 3 is a view taken along the ■ arrow in Figure 2, Figures 4 and 5 are cross-sectional views corresponding to Figure 3 of another embodiment, and Figure 6 is a cross-sectional view of Figure 1 taken along the line ■. Figure 5147 is a cross-sectional view of the main part of a conventional piston fluid machine, and Figure 5147 is an explanatory cross-sectional view for explaining the lateral force and pressure distribution acting on the piston. DESCRIPTION OF SYMBOLS 1...Main shaft, 2...Cylinder barrel, 3...Piston, 14...Cylinder, 5...Button shoe-5a-
YenJttJTlt, i5b, 5C
, 5d... Kiyoshi, 6... Shie, 7... Swash plate box, 8
... Swash plate, 9-a port plate, 9a @ Φ suction and discharge port, 10... Sphinx line, 11. Spherical seat. Patent Applicant Mitsubishi Heavy Industries, Ltd. Sub-Agent Patent Attorney Tetsuji Ozono Figure 1 Figure 211 Figure 6 Figure 7 Procedural Amendment (Method) August 21, 1985

Claims (1)

[Claims] In a piston-type fluid machine in which a piston is reciprocated within a plurality of cylinders that are bored in the axial direction on the same circumference of a cylinder barrel that rotates around the axis, the inner circumferential surface of the cylinder on which the piston slides. A piston-type fluid machine characterized by forming a groove in the umbrella part in the direction in which centrifugal force is applied.