JPH08312781A - Piston ring made of resin - Google Patents

Abstract

PURPOSE: To further improve wear resistance compared with a conventional type, in a piston ring made of resin fitted in a piston without having an abutment part. CONSTITUTION: The sectional shape in a radial direction of a slide part 1a is formed approximately in a U-shape protruding to the outside, and the slide part is fitted in the ring groove 100a of a piston 100 in such a manner that a bending stress is generated on the approximately U-shaped section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin piston ring.

[0002]

2. Description of the Related Art Generally, a piston ring used for a piston of an internal combustion engine is made of metal because it requires high abrasion resistance against sliding on the inner wall of the cylinder. , Such a metal piston ring has an abutment part in order to enable fitting to the piston and to allow contact with the inner wall of the cylinder by exhibiting a spring function. Part of the air-fuel mixture or combustion gas in the combustion chamber flows out into the crank chamber through the section, and the engine oil in the crank chamber easily flows into the combustion chamber, failing to provide high sealing performance.

Japanese Unexamined Patent Publication (Kokai) No. 6-81953 discloses a piston made of a resin having a higher flexibility than metal in order to enable fitting to the piston without providing a joint for the purpose of improving sealing performance. It is disclosed that a ring is formed, and in order to improve abrasion resistance in the sliding portion, reinforcing fibers or the like are mixed in the resin.

[0004]

In the above-mentioned prior art, sufficient abrasion resistance cannot be obtained only by the reinforcing fibers, and the abrasion resistance is considerably inferior to that of the metal piston ring. It was

Therefore, it is an object of the present invention to further improve the abrasion resistance of a resin piston ring which can be fitted into a piston without having an abutment portion as compared with the conventional case.

[0006]

A resin piston ring according to the present invention as set forth in claim 1 is molded without having an abutment portion, and its sliding portion has a substantially U-shaped cross section in the radial direction. It has a character shape and is fitted in the ring groove of the piston so that a bending stress is generated on the substantially U-shaped cross section.

A resin piston ring according to a second aspect of the present invention is the resin piston ring according to the first aspect, which is formed of resin mixed with reinforcing fibers, and the reinforcing fibers are circumferentially arranged. It is characterized in that it is not oriented in.

A resin piston ring according to a third aspect of the present invention is the resin piston ring according to the first aspect, which is formed from a polymer composite having a rigid component, wherein the rigid component is It is characterized in that it is not oriented in the direction.

[0009]

In the resin piston ring according to the present invention as set forth in claim 1, the cross-sectional shape of the sliding portion in the radial direction has a substantially U-shape that is convex outward, and is bent on this substantially U-shape section. Since it is fitted into the ring groove of the piston so that stress is generated, the outside of the sliding part that becomes the sliding surface is stretched and hardened in the sliding direction, but the flexibility of the piston ring in the circumferential direction is Maintained.

The resin piston ring according to a second aspect of the present invention is the resin piston ring according to the first aspect, which is formed of a resin mixed with reinforcing fibers, and the reinforcing fibers are arranged in the circumferential direction. Since it is not oriented in the direction, the hardness of the sliding portion in the sliding direction can be improved without significantly impairing the flexibility in the circumferential direction.

A resin piston ring according to a third aspect of the present invention is the resin piston ring according to the first aspect, which is formed of a polymer composite having a rigid component, and the rigid component has a circumference. Since it is not oriented in the direction, the hardness in the sliding direction at the sliding portion can be improved without significantly impairing the flexibility in the circumferential direction.

[0012]

1 is a view showing a first embodiment of a resin piston ring according to the present invention. The piston ring 1 of the present embodiment is injection-molded into a ring shape without a cut of fluororesin (for example, tetrafluoroethylene or the like) or fluororubber, and as shown in FIG. The thickness is relatively thin, and has a vertically long rectangular shape as a radial cross section before the piston fitting. Figure 1 (B)
It is an expanded sectional view showing the state where it was fitted in ring groove 100a of piston 100. The ring groove 100a is formed by a bottom wall parallel to the piston axis and two side walls perpendicular to the bottom wall. As shown in the figure, the piston ring 1
Is substantially U-shaped in the radial direction of the sliding portion 1a with the inner wall of the cylinder 101 with respect to the ring groove 100a having a width h (distance between side walls) smaller than the height H1 thereof before the piston is fitted. Like, it is bent and fitted.

In the piston ring 1 of this embodiment fitted in the piston 100 in this way, bending stress is generated on the radial cross section outside the sliding portion 1a, that is, on the sliding surface, and the resin Since it is stretched in the sliding direction and becomes very hard, it is possible to provide excellent wear resistance.
Further, since the resin does not extend in the circumferential direction and the flexibility of the resin is maintained in this direction, fitting to the piston 100 can be realized without a cut.

FIG. 2 is a view showing a second embodiment of the resin piston ring according to the present invention. The piston ring 2 of this embodiment is injection-molded from a material similar to that of the first embodiment in a ring shape without cuts, and as shown in FIG.
The plate is relatively thin and has a substantially circular donut shape as a radial cross section before the piston is fitted. Figure 2
(B) is an enlarged cross-sectional view showing a state in which the piston 100 is fitted in the ring groove 100a. The ring groove 100a having a width h smaller than the height H2 of the piston ring before fitting the piston is crushed. It has been fitted.

In the piston ring 2 of this embodiment fitted in the piston 100 in this way, the resin is applied in the sliding direction on the outside of the sliding portion 2a, that is, on the sliding surface, as in the first embodiment. Due to being stretched and very hard, it can provide excellent wear resistance. Further, since the flexibility of the resin is maintained in the circumferential direction, the piston 100 can be fitted without any cuts.

FIG. 3 is a diagram showing a third embodiment of the resin piston ring according to the present invention. The piston ring 3 of this embodiment is injection-molded from a material similar to that of the first embodiment in a continuous ring shape, and as shown in FIG.
The plate thickness is relatively thin, and has a radial cross-sectional shape in which the piston ring 1 of the first embodiment is bent halfway to be fitted on the piston 100 before the piston is fitted. FIG. 3B shows the ring groove 10 of the piston 100.
It is an enlarged cross-sectional view showing a state of being fitted in 0a, and is bent so that the height H3 becomes smaller with respect to the ring groove 100a having a width h smaller than the height H3 of the piston ring before fitting the piston. It is fitted.

The piston ring 3 of this embodiment fitted to the piston 2 in this manner has an outer side of the sliding portion 3a,
That is, on the sliding surface, since the resin is stretched in the sliding direction and becomes extremely hard as in the first embodiment, excellent abrasion resistance can be provided. Further, since the flexibility of the resin is maintained in the circumferential direction, the fitting to the piston 2 can be realized without having a cut.

FIG. 4 is an enlarged view of a fourth embodiment of the resin piston ring according to the present invention, which is equivalent to FIG. 1 (A). The piston ring 1'of this embodiment has the same shape as that of the first embodiment, but the reinforcing fiber 5 such as carbon fiber, aramid fiber or glass fiber is contained in the resin.
Is mixed, and the resin is injection-molded or roll-stretch-molded so that the resin flows only in the axial direction of the piston ring 1 '. Thereby, all the reinforcing fibers 5 are oriented in the axial direction within the piston ring 1 '.

In the thus-formed piston ring 1'of the present embodiment, the reinforcing fiber 5 does not impair the circumferential flexibility, and the piston 100 as shown in FIG.
When it is used by being fitted in, the reinforcing fiber 5 considerably increases the hardness of the sliding portion in the sliding direction, and can greatly improve the abrasion resistance as compared with the first embodiment. .

In the present embodiment, the reinforcing fibers 5 are oriented in the axial direction of the piston ring 1 ', but when such reinforcing fibers are mixed in the resin, they are reinforced at least in the circumferential direction of the piston ring 1'. As long as the fibers are not oriented, it is possible to improve the abrasion resistance of the sliding portion without significantly impairing the flexibility in the circumferential direction as compared with the first embodiment.

When a resin of high crystallinity, crystallinity, or a polymer composite containing them is used as the material of the piston ring 1 ', such a rigid component is used as a substitute for the reinforcing fiber and is oriented as described above. Also by doing so, it is possible to improve the abrasion resistance of the sliding portion without significantly impairing the flexibility in the circumferential direction.

FIG. 5 is an enlarged view of a fifth embodiment of the resin piston ring according to the present invention, which is equivalent to FIG. 1 (A). The piston ring 1 ″ of this embodiment has the same shape as that of the first embodiment, but at the time of resin injection molding or press molding, for example, the reinforcing fiber as described above is used for the warp yarn, A reinforcing cloth member 6 in which stretchable fibers are used for the weft is arranged in the circumferential direction.

In the piston ring 1 "of this embodiment thus molded, the reinforcing cloth member 6 functions in the same manner as the reinforcing fiber of the fourth embodiment, and the flexibility in the circumferential direction is not impaired at all. When the piston 100 is fitted and used as shown in FIG. 1B, the abrasion resistance of the sliding portion can be greatly improved as compared with the first embodiment.

As described above, the idea of increasing the hardness in the sliding portion without impairing the circumferential flexibility of the piston ring by the reinforcing fiber, the rigid component contained in the resin, or the reinforcing cloth member is, of course, It is also applicable to the shapes of the second and third embodiments.

In all of the above-mentioned embodiments, when the piston ring is fitted in the ring groove of the piston, the radial cross section of the sliding portion is formed into a substantially U shape with an outward convex shape, and bending stress is applied to the cross section. Is to occur. Even if the bending stress causes plastic deformation of the resin to be used, the flexibility of the resin in the circumferential direction is maintained, the resin can be fitted into the piston without notches, and the metal piston having an abutment is formed. The sealability can be improved as compared with the ring, and the hardness at the sliding portion can be increased to improve the wear resistance as compared with the usual resin piston ring.

For example, as shown in FIG. 6, the piston ring 1 of the first embodiment shown in FIG. 1 is fitted into the ring groove 100a 'deepened inward, whereby the piston ring 1 and the ring are fitted. It is also possible to arrange a backup ring 7 or the like for urging the piston ring 1 outward in a space formed between the groove 100a ′ and the bottom wall. Thereby, the sealability between the piston ring 1 and the inner wall of the cylinder 101 can be further improved.

Further, when such a space is formed, the piston ring does not follow the piston and is not eccentric when a force acting on the piston is eccentric with respect to the center of the cylinder, as in an internal combustion engine. It is possible to provide high sealability. Of course, such a configuration is also possible in the piston rings of the second and third embodiments.

As described above, when the piston ring slides on the side wall of the ring groove, the reinforcing fibers 5 are oriented or the reinforcing cloth member 6 is arranged as in the fourth and fifth embodiments. The hardness in this sliding direction is also increased,
It is possible to improve not only the wear resistance of the resin piston ring on the inner wall of the cylinder but also the wear resistance of the side wall of the ring groove.

In all of the embodiments, the sealing property between the piston ring and the ring groove is similar to that of the metal piston ring, because the friction between the piston ring and the inner wall of the cylinder causes the piston ring to adhere to one of the side walls of the ring groove. However, as shown in FIGS. 1 to 3, the flexibility of the resin piston ring in the circumferential direction is utilized to bring the inside of the piston ring into close contact with the ring groove, thereby further improving the sealing performance. Can be made.

Further, in all of the above-described embodiments, the bending stress generated in the sliding portion is within the elastic deformation of the resin, so that the piston ring can be brought into close contact with the side wall of the ring groove and the piston ring and the ring. The sealing property with the groove can be further improved. Further, in order to reduce the frictional force between the sliding portion of the piston ring and the inner wall of the cylinder, it is possible to add an additive such as molybdenum disulfide or graphite to the resin for molding the piston ring.

[0031]

As described above, according to the resin piston ring of the present invention as set forth in claim 1, the sliding portion has a substantially U-shaped cross-section in the radial direction, which is convex toward the outside. Since it is fitted into the ring groove of the piston so that bending stress is generated on the U-shaped cross section, the outside of the sliding part that becomes the sliding surface is stretched in the sliding direction and becomes harder. The flexibility in the circumferential direction is maintained, it can be fitted in the ring groove of the piston without having an abutment, and it is possible to provide considerably higher sealability compared to the metal piston ring, and it is possible to provide conventional resin. It is possible to easily increase only the hardness of the sliding portion in the sliding direction as compared with the manufactured piston ring, and it is possible to greatly improve the wear resistance.

According to the resin piston ring of the present invention as defined in claim 2, reinforcing fibers are mixed in the resin and the reinforcing fibers are not oriented in the circumferential direction. Compared with the resin piston ring described in, it is possible to further increase the hardness in the sliding direction in the sliding portion without significantly impairing the flexibility in the circumferential direction, and further improve the wear resistance in the sliding portion. Can be improved.

According to the resin piston ring of the present invention as defined in claim 3, a polymer composite having a rigid component is used as the resin, and the rigid component is not oriented in the circumferential direction. As compared with the resin piston ring according to claim 1, the hardness in the sliding direction in the sliding portion can be further increased without significantly impairing the flexibility in the circumferential direction, and the abrasion resistance in the sliding portion can be improved. The wear resistance can be further improved.

[Brief description of drawings]

FIG. 1 shows a first embodiment of a resin piston ring according to the present invention, (A) is a radial cross-sectional view, and (B) is an enlarged cross-sectional view showing a fitting state in a ring groove.

2A and 2B show a second embodiment of the resin piston ring according to the present invention, FIG. 2A is a radial sectional view, and FIG. 2B is an enlarged sectional view showing a fitting state in a ring groove.

3A and 3B show a third embodiment of a resin piston ring according to the present invention, FIG. 3A being a radial sectional view, and FIG. 3B being an enlarged sectional view showing a fitting state in a ring groove.

FIG. 4 is an enlarged view of a diagram corresponding to FIG. 1A showing a fourth embodiment of the resin piston ring according to the present invention.

FIG. 5 is an enlarged view of a diagram corresponding to FIG. 1A showing a fifth embodiment of the resin piston ring according to the present invention.

FIG. 6 is an enlarged view of a diagram corresponding to FIG. 1 (B) showing a sixth embodiment of the resin piston ring according to the present invention.

[Explanation of symbols]

 1, 2, 3, 1 ', 1 "... Resin piston ring 5 ... Reinforcing fiber 6 ... Reinforcing cloth member 7 ... Backup ring 100, 100' ... Piston 100a, 100a '... Ring groove 101 ... Cylinder

Claims (3)

[Claims] 1. A structure which is molded without an abutment, has a substantially U-shaped cross-section in the radial direction at the sliding portion, and is bent so that bending stress is generated on the substantially U-shaped cross section. A resin piston ring that is fitted in the ring groove of the piston. 2. The resin piston ring according to claim 1, wherein the resin piston ring is formed of a resin in which reinforcing fibers are mixed, and the reinforcing fibers are not oriented in the circumferential direction. 3. The resin piston ring according to claim 1, wherein the resin piston ring is formed of a polymer composite having a rigid component, and the rigid component is not oriented in the circumferential direction.