JP2001330151A - Piston ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston ring capable of maintaining a tension to the outside in the radial direction of a piston without the occurrence of a crack to an abutment part even during high load combustion. SOLUTION: This piston ring 10 consists of an outer ring 11, and an inner ring 12. The outer ring 11 is formed of a member being a solid member, a film 11A is formed on its outer peripheral surface and effects slide over the inner peripheral surface of a cylinder. The length in a radial direction of a piston in the cross section of the outer ring 11 is shorter than the length in an axial direction of the piston. The inner ring 12 is a backup ring formed of a solid member and the length in a radial direction of the piston in the cross ring of the inner ring 12 is longer than the length in an axial direction of the piston. An outer peripheral surface 12A of the inner ring 12 makes contact with an inner peripheral surface 11B of the outer ring 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston ring,
In particular, it relates to a piston ring used as a so-called pressure ring on the side closer to the combustion chamber.

[0002]

2. Description of the Related Art Conventionally, as a piston ring inserted into a piston ring groove, a type including an outer ring and an inner ring has been known. In this type, the outer peripheral surface of the inner ring is arranged in contact with the inner peripheral surface of the outer ring. When the inner ring and the outer ring are inserted into the piston ring grooves, tension is generated in the inner ring and the outer ring, respectively, which is directed outward in the piston radial direction.
The tension generated in the inner ring assists the tension of the outer ring.

[0003] More specifically, as shown in FIG.
The piston ring 110 is composed of an outer ring 111 and a corrugated inner ring 112, which are formed in a piston ring groove 12 formed in a piston 120.
0a. The outer ring 111 has a rectangular cross section and is formed of a solid member. As a material of the outer ring 111, a material obtained by applying a PVD coating, chrome plating, nitriding, or the like to an outer peripheral surface side of a steel base material is used. The inner ring 112 has a plate shape like a leaf spring. The inner ring 112 has a slot 112a penetrating the inner ring 112 in the radial direction of the piston. The length of the inner ring in the piston radial direction is about 0.5 to 0.8 mm
And the length in the axial direction of the piston is 2 to 5 mm. Steel is used as a material of the inner ring 112. The outer peripheral surface 112A of the inner ring is disposed substantially parallel to the inner peripheral surface 111A of the outer ring 111.

When the inner ring 112 is inserted into the piston ring groove 120a, it bulges outward in the radial direction of the piston at six to eight locations in the circumferential direction, and as shown in FIG. Of the outer ring 111 abuts on the inner peripheral surface 111A of the outer ring 111. Outer ring 1
When the outer ring 111 is inserted into the piston ring groove 120a, tension is generated in the outer ring 111 itself in the radial direction of the piston, but the outer peripheral surface 112A of the inner ring 112 is fixed to the inner peripheral surface 111A of the outer ring 111.
Contact with the inner ring 112 and the outer ring 1
The inner ring 112 assists the tension of the outer ring 111 outward in the piston radial direction by pressing the outer ring 11 outward in the piston radial direction.

On the other hand, Japanese Utility Model Publication No. 38-21003 discloses a piston ring having an inner ring obtained by spirally winding a steel wire. As shown in FIG. 4, the piston ring 210 includes an outer ring 211 and an inner ring 212, which are inserted into a piston ring groove 220 a formed in the piston 220. Outer ring 2
Reference numeral 11 has a rectangular cross section and is made of a solid member. The inner ring 212 is a coil obtained by spirally winding a steel wire, has a substantially elliptical cross section, and the inside of the substantially elliptical shape is hollow.

[0006] When the inner ring 212 is inserted into the piston ring groove 220a, it bulges outward in the radial direction of the piston, and the outer peripheral surface 212A is formed on the inner peripheral surface 2 of the outer ring 211.
Contact 11A. Outer peripheral surface 21 of inner ring 212
2A comes into contact with the inner peripheral surface 211A of the outer ring 211, and the inner ring 212 presses the outer ring 211 outward in the piston radial direction, whereby the inner ring 212 tensions the outer ring 211 outward in the piston radial direction. To assist.

[0007]

However, when the conventional piston ring shown in FIG. 3 is used in a high-load engine, since the inner ring is of a plate type, the inner ring is liable to fatigue due to high heat, and the radial direction of the piston is reduced. In some cases, outward tension was lost.

In recent years, the axial length of a piston has been reduced in order to reduce the size of a high-load engine. If the conventional piston ring described above is used to shorten the axial length of the piston, the axial length in the cross section of the outer ring should be considerably smaller than the radial length of the piston. Is usually performed. By this, the length in the piston radial direction in the cross section of the outer ring is relatively
It is much larger than the length in the axial direction of the piston. In order to increase the tension of the outer ring itself in the radial direction of the piston, the length of the cross section of the outer ring in the radial direction of the piston is usually made considerably larger than the length in the axial direction of the piston.

When the length of the outer ring in the radial direction of the piston is increased, the difference between the outer peripheral surface temperature and the inner peripheral surface temperature of the outer ring, and the outer peripheral surface of the outer ring and the inner peripheral surface of the outer ring are reduced. The difference between the expansion coefficient of the inner peripheral surface of the outer ring and the expansion coefficient of the outer peripheral surface during high load combustion causes a high surface pressure to act on the abutment,
There have been problems such as cracks occurring at the abutment portion of the outer ring that slides on the inner peripheral surface of the cylinder, and the coating at the abutment portion being peeled off.

Accordingly, an object of the present invention is to provide a piston ring which does not generate cracks or the like at an abutment portion even at the time of high load combustion and can maintain a tension outward in a piston radial direction.

[0011]

In order to achieve the above object, the present invention provides an outer member which is inserted into a piston ring groove formed in a piston and whose outer peripheral surface slides on the inner peripheral surface of a cylinder. A ring and a biasing member that is inserted into the piston ring groove, is disposed in contact with the inner peripheral surface of the outer ring, and biases the outer ring radially outward of the piston. In the piston ring,
The radial length of the piston in the cross section of the outer ring is equal to or less than the length in the axial direction of the piston, and the biasing member is constituted by a backup ring which is a solid member having a rectangular cross section. A piston ring is provided on the side.

Here, it is preferable that the length in the piston radial direction in the cross section of the backup ring is equal to or greater than the length in the piston axial direction.

[0013] Preferably, a convex portion is provided on one of the inner peripheral surface of the outer ring and the outer peripheral surface of the backup ring, and a concave portion for engaging the convex portion is formed on the other. preferable.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A piston ring according to a first embodiment of the present invention will be described with reference to FIG. A piston ring 10 used as a pressure ring has an outer ring 11 and an inner ring 1 as shown in FIG.
These are fitted coaxially with the piston 20 in a piston ring groove 20a formed in the piston 20. The outer ring 11 is formed of a solid member. As a material of the outer ring 11, steel or cast iron is used as a base material,
The outer peripheral surface is provided with a coating 11A made of PVD coating, chrome plating, nitriding, or the like. The outer ring 11 has a rectangular cross section, and the length in the piston radial direction in the cross section is not more than the length in the piston axial direction and not more than 1/40 of the outer diameter of the outer ring 11. Further, when the piston 20 reciprocates in a cylinder (not shown), the outer ring 11 is prevented from coming off from the piston ring groove 20a so that the outer ring 11 has a radius larger than the gap between the piston outer peripheral surface and the cylinder inner peripheral surface. Direction length.

The inner ring 12 is also formed of a solid member. As a material of the inner ring 12, steel or cast iron is used. The inner ring 12 is a backup ring having a rectangular cross section, and the length in the radial direction of the piston in the cross section is equal to or greater than the length in the axial direction of the piston. The inner ring 12 is the outer ring 11
Are arranged radially inward in the piston radial direction, and the entire outer peripheral surface 12A of the inner ring 12 is
Are arranged so as to be in contact with the entire inner peripheral surface 11B.

Outer ring 11 and inner ring 1
2 is inserted into the piston ring groove 20a,
In order not to match the position of each abutment,
The other fitting is shifted by 180 ° with respect to one fitting with respect to the piston shaft. When the inner ring 12 is inserted into the piston ring groove 20a, it expands outward in the piston radial direction, and the outer peripheral surface 12A of the inner ring 11 contacts the inner peripheral surface 11B of the outer ring 11 as shown in FIG. . When the outer ring 11 is inserted into the piston ring groove 20a, tension is generated in the outer ring 11 itself in the radial direction of the piston, but the outer peripheral surface 12A of the inner ring 12 is , The inner ring 12 presses the outer ring 11 outward in the piston radial direction, so that the inner ring 12 backs up the tension of the outer ring 11 outward in the piston radial direction.

Since the inner ring 12 is formed of a solid member and has a rectangular cross-sectional shape, the inner ring 12 can be moved radially outward even when the piston ring is used in a high-load engine. The tension can be reliably maintained. Also, since the tension of the inner ring 12 can be reliably maintained, the outer ring 1
1, the tension in the radially outward direction of the piston does not need to be so high. Therefore, the length in the piston radial direction in the cross section of the outer ring 11 can be made equal to or less than the length in the piston axial direction, and the difference between the temperature of the outer peripheral surface and the temperature of the inner peripheral surface of the outer ring 11 can be reduced. In addition, the difference between the peripheral length of the outer peripheral surface of the outer ring 11 and the peripheral length of the inner peripheral surface can be reduced. As a result, it is possible to prevent cracks and the like from occurring at the abutment portion of the outer ring 11.

A piston ring according to a second embodiment of the present invention will be described with reference to FIG. The piston ring according to the second embodiment differs from the piston ring according to the first embodiment in the shape of the outer peripheral surface of the inner ring and the shape of the inner peripheral surface of the outer ring that constitute the piston ring. Except for this, the configuration is the same as that of the first embodiment.

The piston ring 30 includes the outer ring 3
1 and an inner ring 32. An outer peripheral surface of the outer ring 31 is provided with a coating 31A such as a PVD coating, chrome plating, or nitride plating.
As shown in FIG. 2, the inner peripheral surface 31 </ b> B of the outer ring 31 is provided with a rectangular convex portion 31 </ b> C protruding inward in the radial direction of the piston.
On the outer peripheral surface 32A of the second 2, a concave portion 32a which is recessed in a rectangular shape inward in the piston radial direction is formed. The concave portion 32a and the convex portion 31C have the same shape, and the convex portion 31C of the outer ring 31 can engage with the concave portion 32a when the inner ring 32 expands outward in the radial direction of the piston due to the tension of the inner ring 32 itself. It is configured.

On the inner peripheral surface 31B of the outer ring 31, a rectangular convex portion 3 protruding inward in the radial direction of the piston.
1C, a concave portion 32a is formed in the outer peripheral surface 32A of the inner ring 32. The convex portion 31C and the concave portion 32a are engaged with each other, so that the outer ring 31 and the inner ring 32 The unity is increased and it is ensured that the piston moves integrally in the axial direction of the piston. Therefore, when the length of the outer ring 31 in the radial direction of the piston is smaller than the gap between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder, when the piston reciprocates in the cylinder, the piston ring groove 20a The outer ring 11 can be prevented from coming off from inside.

The piston ring according to the present invention is not limited to the embodiment described above, and various modifications and improvements can be made within the scope described in the claims. For example, in the piston ring according to the second embodiment, the outer ring 31
The inner peripheral surface 31B of the inner ring 32 is provided with a rectangular convex portion 31C protruding inward in the piston radial direction, and the outer peripheral surface 32A of the inner ring 32 is formed with a concave portion 32a recessed in a rectangular shape inward in the piston radial direction. , May not be rectangular. For example, the convex portion may be formed in a V-shape, and the acute-angled tip of the V-shape may be directed inward in the piston radial direction. In this case, the outer peripheral surface of the inner ring may have the same shape so that the projection can be engaged.

Further, a concave portion which is depressed outward in the radial direction of the piston may be formed on the inner peripheral surface of the outer ring, and a convex portion projecting outward in the radial direction of the piston may be provided on the outer peripheral surface of the inner ring.

The number of convex portions and concave portions is one as in the above-described embodiment.
The number is not limited to one, and there may be more than one.

[0024]

According to the piston ring of the first aspect, since the biasing member is constituted by the backup ring made of a solid member having a rectangular cross section, even when the piston ring is used in a high-load engine, The inner ring tension outward in the piston radial direction can be reliably maintained. For this reason, even if the length in the axial direction of the piston in the cross section of the outer ring is reduced for the purpose of downsizing the engine, the length in the radial direction of the piston in the cross section of the outer ring may be equal to or less than the length in the axial direction of the piston. it can.
As a result, the difference between the temperature of the outer ring outer peripheral surface and the temperature of the inner peripheral surface can be reduced, and the difference between the peripheral length of the outer ring outer peripheral surface and the peripheral length of the inner peripheral surface can be reduced. Can be. As a result, it is possible to prevent the occurrence of cracks and the like in the coating at the abutment portion of the outer ring.

According to the piston ring of the second aspect,
Since the length in the piston radial direction in the cross section of the backup ring is equal to or greater than the length in the piston axial direction, the tension of the outer ring outward in the piston radial direction can be strongly backed up by the backup ring.

According to the piston ring of the third aspect,
A convex portion is provided on one of the inner peripheral surface of the outer ring and the outer peripheral surface of the backup ring, and a concave portion for engaging the convex portion is formed on the other, so that the integrity of the inner ring and the outer ring is ensured. Is done. For this reason, the length of the outer ring in the piston radial direction can be further reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a piston ring according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a piston ring according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional piston ring.

FIG. 4 is a sectional view showing another conventional piston ring.

[Explanation of symbols]

 Reference Signs List 10 piston ring 11 outer ring 11a inner peripheral surface 12 inner ring 12a outer peripheral surface 20 piston 30 piston ring 31 outer ring 31a inner peripheral surface 31b convex portion 32 inner ring 32a outer peripheral surface 32b concave portion

Claims (3)

[Claims] An outer ring which is inserted into a piston ring groove formed in a piston and whose outer peripheral surface slides with respect to an inner peripheral surface of the cylinder; and an outer ring which is inserted and fitted in the piston ring groove. A biasing member disposed in contact with the inner peripheral surface of the piston and biasing the outer ring radially outward of the piston, wherein a length in a piston radial direction in a cross section of the outer ring is provided. The biasing member is constituted by a backup ring which is a solid member having a rectangular cross section, and is disposed on the inner peripheral side of the outer ring. . 2. The piston ring according to claim 1, wherein a length in a radial direction of the piston in a cross section of the backup ring is equal to or longer than a length in a piston axial direction. 3. A convex portion is provided on one of the inner peripheral surface of the outer ring and the outer peripheral surface of the backup ring, and a concave portion for engaging the convex portion is formed on the other. The piston ring according to claim 1 or 2, wherein