JPS6221811Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a piston for a compressor, and more particularly to a seal structure for a piston for a compressor.

Generally, a piston ring is provided with a cut so that when the piston is fitted into a cylinder, it expands radially outward and comes into elastic contact with the inner wall surface of the cylinder.
There is also a compressor piston in which the piston ring is pressed radially outward by a back ring made of an elastic member to ensure contact or sealing between the piston ring and the inner wall surface of the cylinder. However, in such a compressor, the sealing surface pressure of the piston ring against the inner wall of the cylinder is the same during both the compression stroke and the suction stroke of the piston. That is, even during the suction stroke when the seal surface pressure is low, the seal surface pressure is relatively high, and the sliding resistance of the piston is correspondingly high, so that smooth movement of the piston cannot be expected.

Therefore, an object of the present invention is to provide a device that eliminates the drawbacks of the conventional devices described above, that is, a piston that can obtain high sealing pressure during the compression stroke and low sealing pressure during the suction stroke. A piston for a compressor, in which a piston ring is fitted around the outer periphery of a piston that reciprocates slidably within a cylinder, and the piston ring is pressed in a radial outward direction by a back ring installed in a groove inside the piston ring. , a chamber in which the distance in the piston radial direction between the bottom surface of the groove and the inner surface of the piston ring that the back ring contacts is gradually increased in the piston compression movement direction, and the groove space is located in the piston compression movement direction by the back ring and communicates with the compression chamber. A piston for a compressor, characterized in that the piston is divided into a chamber located in the suction movement direction of the piston.

An embodiment of a compressor piston according to the present invention will be described below with reference to the accompanying drawings. A compressor 10 shown in FIG. 1 is a reciprocating single-stage compression type compressor, and a piston 20 according to the present invention is fitted into a cylinder 11 so as to be able to reciprocate in a sealed state. The piston 20 is the cylinder 1
A compression chamber 12 is divided into one internal space. At the upper end of the cylinder 11 adjacent to the compression chamber 12, a suction valve 13 and a discharge valve 14 are provided. The suction valve 13 opens when the piston 20 descends, and atmospheric air is sucked into the compression chamber 12. Next, when the piston 20 moves up, the suction valve 13 closes, but the discharge valve 14, which has been closed until now, opens and compressed air is discharged.

The piston 20 compresses air by reciprocating as described above, and this driving force is obtained from the electric motor 15. That is, the rotational motion of the motor 15 is converted into a reciprocating motion by the crank mechanism 16, and the connecting rod 17 of the crank mechanism 16 causes the reciprocating motion.

As shown in FIG. 2, the piston 20 according to the present invention includes a piston body 21 and a piston pin 2 that connects the connecting rod 17 and the piston body.
2, a bush or piston ring 23 provided on the outer periphery of the piston body 21, and a back ring 24 that presses the piston ring 23 in a radially outward direction.

A recess 25 is provided in the center of the piston body 21 to accommodate the end 17a of the connecting rod 17, and the piston pin 22 passes through the end 17a of the connecting rod 17, with both ends of the piston body It is press-fitted and fixed to the side of 21. A bushing 26 is fitted between the piston pin 22 and the end 17a of the connecting rod 17, so that the connecting rod 17 can easily swing around the axis of the piston pin 22. .
The piston pin 22 has a length such that when it is press-fitted into the piston body 21 as shown in FIG. 2, neither end of the pin 22 protrudes from the bottom of a piston ring fitting groove 27, which will be described below. .

Groove 27 provided on the outer peripheral surface of the piston body 21
A bush or piston ring 23 is fitted in the . The surface of the piston ring 23 is coated with a wear-resistant material such as Teflon to improve wear resistance. A groove 28 is further provided above the piston ring fitting groove 27 to accommodate the back ring 24 in the radial inward direction. This back ring 24 presses the piston ring 23 in a radially outward direction to improve the sealing performance of the piston ring 23. The piston ring 23 is cut to form a stepped mating opening, and even if the diameter increases or decreases due to the back ring 24, the degree of sealing will not decrease. As already mentioned, the width of the piston ring 23 is only slightly shorter than the total height of the piston body 21, and therefore it covers the outlet of the piston pin 22 mounting hole of the piston body 21. In the illustrated embodiment, a wide piston ring 23 is used, but a normal piston ring 23 can also be used in the piston 20 according to the present invention.

Bottom surface 2 of groove 28 into which back ring 24 is fitted
9 is a tapered surface as shown in FIGS. 2 and 3. That is, the diameter around the piston axis (a in Fig. 2) in the direction of movement of the piston 20 during the compression stroke.
) is tapered so that it gradually becomes smaller. In FIGS. 2 and 3, only the bottom surface 29 of the fitting groove 28 in the piston radial direction is tapered, but as shown in FIG.
It is possible to taper only the inner surface 23a of the piston ring 23 with which it comes into contact, or it is also possible to tape both the groove bottom surface 29 and the inner surface 23a of the piston ring 23. By tapering one or both of the surfaces that the back ring 24 contacts, the distance in the piston radial direction between the groove bottom surface 29 that the back ring 24 contacts and the inner surface 23a of the piston ring 23 can be adjusted in the piston compression movement direction. gradually increase to The angle between the groove bottom surface 29 and the piston ring inner surface 23a is preferably about 3 to 10 degrees.
Therefore, the back ring 24 is held between the groove bottom surface 29 and the inner surface 23a of the piston ring 23.
Therefore, the piston ring 23 divides the space formed by the groove 28 and the piston ring 23 into a chamber 30 located above, that is, in the direction of piston compression movement, and communicating with the compression chamber, and a chamber 31, located below, that is, in the direction of piston suction movement. do.

To explain the operation of the piston 20 according to the present invention, when the piston 20 rises for compression,
The air within the compression chamber 12 is compressed to a high pressure. For this purpose, high pressure air is introduced into the chamber 30. Therefore, the back ring is pressed downward and moves. Since the lower portion is narrower than the upper portion, the piston ring 23 is pressed radially outward as shown by arrow F, thereby increasing the sealing surface pressure of the piston 20 against the cylinder inner wall surface. Further, during the suction stroke of the piston 20, the pressure within the compression chamber 12, that is, the pressure in the chamber 30 becomes low, and the back ring 24 is sucked upward, so that the seal surface pressure, which had been high during the compression stroke, becomes low.

The structure and operation of the piston 20 according to the present invention are as described above, and the sealing surface pressure between the piston 20 and the inner wall of the cylinder 11 increases during the piston compression stroke, so the sealing performance is high.On the other hand, during suction, the piston 20 slides. This has the effect that resistance is reduced and smooth movement of the piston 20 can be expected. Furthermore, since unnecessary seal surface pressure is eliminated during suction, unnecessary wear of the piston ring 23 and the inner wall surface of the cylinder 11 is prevented.
The life of the compressor 10 using 0 is also greatly increased, and the practical value is great.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a reciprocating single-stage compression compressor using the piston according to the present invention, Fig. 2 is a cross-sectional view of the piston according to the present invention, and Fig. 3 is a partial enlargement of the piston shown in Fig. 2. 4 is a partially enlarged sectional view showing another embodiment of the piston shown in FIG. 3; FIG. 20...piston, 23...piston ring,
23a... Piston ring inner surface, 24... Back ring, 28... Back ring fitting groove, 29...
Groove bottom.

Claims (1)

[Claim for Utility Model Registration] A piston ring is fitted around the outer periphery of a piston that is slidably housed in a cylinder, and a back ring installed in a groove inside the piston ring presses the piston ring in a radial outward direction. In this compressor piston, the distance in the radial direction of the piston between the bottom surface of the groove and the inner surface of the piston ring that the back ring contacts is gradually increased in the direction of piston compression movement, and the space inside the groove is moved in the direction of piston compression movement by the back ring. A piston for a compressor, characterized in that the piston is divided into a chamber located therein and communicating with the compression chamber, and a chamber located in the suction movement direction of the piston.