KR101823807B1 - Piston ring and engine comprising said piston ring - Google Patents

Abstract

A piston ring of a gas-tight type in which the high-pressure and high-speed blowing of the combustion gas in the non-overlapping regions of the first tongue portion and the second tongue portion are suppressed and the durability is improved, and an engine provided with the piston ring The piston ring 10 includes a body portion 10a and a pair of piston rings 10a and 10b extending from one end of the body portion 10a to the other end and extending radially outwardly of the body portion 10a and extending in the circumferential direction on one side in the axial direction The first tongue portion 12 is formed with a first tongue portion 12 and a second tongue portion 12b extending from the other end of the main body portion 10a at one end and fitted into the fitting groove 12c. Overlapping regions S1 and S2 in which the first tongue portion 12 and the second tongue portion 13 do not overlap with each other in the direction along the axial line of the first tongue portion 12 The outer circumferential surface 12d of the second tongue 13 and the outer circumferential surface 13d of the second tongue 13, And, it provided with a communication groove (G1, G2) which communicates in the axial direction.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a piston ring and an engine equipped with the piston ring,

The present invention relates to a piston ring and an engine equipped with the piston ring.

The piston ring is mounted in the piston ring groove formed in the outer periphery of the piston. The piston ring has elasticity and has a function of maintaining the pressure in the combustion chamber formed by the piston, the inner circumferential surface of the cylinder, and the cylinder head by sliding contact with the inner circumferential surface of the cylinder with an appropriate surface pressure.

The piston ring has a ring shape, and a discontinuous portion called a fitting portion is formed in a part of the piston ring in the circumferential direction. For example, the gas tight type fitting portion as described in Patent Document 1 is composed of a concave portion formed at one end side in the circumferential direction of the piston ring and a convex portion formed at the other end side, And are fitted to overlap each other.

Japanese Patent Application Laid-Open No. 7-332496

During operation of the engine, the piston rings become hot due to being heated by the combustion gas. At this time, since the outer peripheral side of the piston ring is in sliding contact with the relatively low-temperature inner peripheral surface of the cylinder, the temperature of the inner peripheral side of the piston ring becomes higher than the temperature of the outer peripheral side. Therefore, the amount of thermal expansion of the piston ring becomes larger on the inner circumferential side than on the outer circumferential side, and thermally deforms such that the summed portion of the piston ring bulges outward in the radial direction of the piston ring.

Such thermal deformation increases the contact surface pressure between the concave portion (first tongue portion) and the convex portion (second tongue portion) constituting the merging portion and the inner circumferential surface of the cylinder, and imbalance occurs on the inner circumferential surface of the cylinder in the vicinity of the merging portion. On the other hand, when the tip end side of the first tongue portion and the second tongue portion are about to bulge outward in the radial direction due to thermal deformation, the radius of curvature of the first tongue portion and the second tongue portion becomes larger than the radius of curvature of the inner circumferential surface of the cylinder, The root side of the two tongues is easily separated from the inner circumferential surface of the cylinder.

For this reason, in the case where uneven wear occurs on the inner circumferential surface of the cylinder due to thermal deformation, a slight gap may be generated between the root side of the thermally deformed first tongue portion and the second tongue portion and the inner circumferential surface of the cylinder. Then, the high-temperature combustion gas is introduced into the region near the root of the first tongue portion and the second tongue portion, that is, in the region where the first tongue portion and the second tongue portion do not overlap each other (non-overlapping region) To the high pressure and high speed. Such blowing of the combustion gas causes a problem that the outer circumferential surface of the piston ring is damaged in the non-overlapping region.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problem, and it is an object of the present invention to provide a gas-tight piston ring in which durability is improved by suppressing high-pressure and high-speed blowing of combustion gas in non- overlap regions of the first tongue portion and the second tongue portion, And an object of the present invention is to provide an engine having a piston ring.

In order to solve the above-described problems, a piston ring according to the present invention includes:

A body portion extending along a circumferential direction around the axis,

A first tongue portion extending from one end of the body portion to the other end and having a fitting groove extending radially outwardly of the body portion and extending along the circumferential direction on one side in the axial direction;

A second tongue portion extending from the other end of the body portion to the one end and forming a joint portion together with the first tongue portion by fitting into the fitting groove;

And a communicating groove formed in at least one of an outer circumferential surface of the first tongue portion and an outer circumferential surface of the second tongue portion in a non-overlapping region in which the first tongue portion and the second tongue portion do not overlap with each other.

According to this structure, by forming the communication groove in advance in at least one of the outer circumferential surface of the first tongue portion and the outer circumferential surface of the second tongue portion in the non-overlapping region in advance, the combustion gas can be emitted through the communication groove, Is prevented from escaping at a high pressure and at a high speed. As a result, the damage in the non-overlapping region is suppressed, and the durability of the piston ring is improved.

Further, by forming the communication groove, the rigidity of at least one of the first tongue portion and the second tongue portion is lowered, and the contact surface pressure of the piston ring with respect to the cylinder inner circumferential surface is made uniform. As a result, uneven wear of the piston ring and the inner circumferential surface of the cylinder 2a is suppressed, and the durability of the piston ring is improved.

In some embodiments,

The communication groove is formed on both the outer circumferential surface of the first tongue portion and the outer circumferential surface of the second tongue portion.

According to this configuration, by forming the communication grooves in both the outer circumferential surface of the first tongue portion and the outer circumferential surface of the second tongue portion in the non-overlapping region, high-speed and high-pressure blowing of the high temperature combustion gas in these two non- So that the damage of the piston ring can be further prevented.

In some embodiments, the cross-section of the communication groove in the radial direction is formed in a semicircular shape.

According to this configuration, the cross-sectional shape of the cross-section perpendicular to the axial line has a semicircular cross-sectional shape, so that the cross-sectional shape near the cross-sectional shape of the cross-section is smooth. As a result, the concentration of stress in the vicinity of the communication groove is relaxed, and the durability of the piston ring can be improved.

In some embodiments, the cross-sectional area of the communication groove in the radial direction increases from one side to the other side in the axial direction.

According to this configuration, when the combustion gas flows from one side to the other side by increasing the cross-sectional area of the communication groove from one side to the other side in the direction along the axial line, It is possible to reduce the speed of the combustion gas. Therefore, when another piston ring is disposed beside the piston ring, the impact pressure of the combustion gas on the other piston ring can be reduced, and the durability of the other piston ring is improved.

The engine according to the present invention is provided with any one of the above piston rings.

According to this configuration, in the piston ring, the high-pressure and high-speed blowing of the combustion gas in the non-overlapping regions of the first tongue portion and the second tongue portion is suppressed and the durability of the piston ring is improved, do.

In some embodiments, the cross-sectional area of the communication groove in the radial direction is configured to increase from the combustion chamber side of the engine toward the crank chamber side in the axial direction.

According to this configuration, when the combustion gas flows from the combustion chamber side toward the crank chamber side, the speed of the combustion gas flowing out from the crank chamber side of the communication groove can be reduced.

Therefore, when another piston ring is disposed on the crank chamber side of the piston ring, the impact pressure of the combustion gas on the other piston ring can be reduced, and the durability of the other piston ring is improved.

According to the present invention, there is provided a gas-tight type piston ring in which the high-pressure and high-speed blowing of the combustion gas in the non-overlapping regions of the first tongue portion and the second tongue portion are suppressed and durability is improved, and an engine equipped with the piston ring / RTI >

1 is a schematic cross-sectional view of an engine to which a piston ring according to the present invention is applied.
2 is a perspective view showing a schematic appearance of a piston ring according to a first embodiment of the present invention.
3 is a plan view schematically showing an enlarged area A of FIG. 2 together with a part of the cylinder.
Fig. 4 is a perspective view schematically showing an enlarged area A of Fig. 2. Fig.
Fig. 5 is a perspective view corresponding to Fig. 4 of the piston ring according to the second embodiment of the present invention. Fig.
Fig. 6 is a perspective view corresponding to Fig. 4 of the piston ring according to the third embodiment of the present invention. Fig.
Fig. 7 is a perspective view corresponding to Fig. 4 of the piston ring according to the fourth embodiment of the present invention. Fig.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

However, the dimensions, materials, shapes, relative positions, and the like of the constituent parts described in the embodiments are not intended to limit the scope of the present invention only to the specific examples, and are merely illustrative examples thereof.

(First Embodiment)

1 is a cross-sectional view schematically showing a configuration of an engine 1 to which a piston ring 10 according to a first embodiment of the present invention is applied. The engine 1 is, for example, a two-cycle large-scale diesel engine for marine use.

The engine 1 is provided with a cylinder 2, a piston 3 arranged so as to freely reciprocate in the cylinder 2, and a cylinder head 4 covering one end of the cylinder 2. On one end side of the cylinder 2, the combustion chamber 5 is partitioned by the cylinder 2, the piston 3, and the cylinder head 4.

The piston rod 3a extends from the opposite side of the combustion chamber 5 of the piston 3 and the piston rod 3a is connected to the other end side of the cylinder 2 It is penetrating. The opposite side of the piston rod 3a from the piston 3 is connected to the crankshaft in the crank chamber through a crosshead and a connecting rod (not shown). In the case where the engine 1 is, for example, a Uniformizer type, an exhaust port is formed in the cylinder head 4, and a scavenging port (not shown) is formed on the other end side of the cylinder 2.

The piston ring (10) is mounted on the outer peripheral portion of the piston (3). Concretely, a piston ring groove 6 is formed in the outer peripheral portion of the piston 3, and the piston ring 10 is fitted in the piston ring groove 6. The piston ring 10 is disposed coaxially with the cylinder 2 and the piston 3 and the axis CL of the piston ring 10 coincides with the axis of the cylinder 2 and the piston 3 have.

The piston ring 10 protrudes outward from the outer circumferential surface of the piston 3 in the radial direction of the piston 3 and has an outer circumferential surface slidingly contacting the inner circumferential surface (cylinder inner circumferential surface) 2a of the cylinder 2. The gap between the inner circumferential surface 2a of the cylinder 2a and the outer circumferential surface of the piston 3 is closed by the piston ring 10 and the pressure of the combustion chamber 5 can be maintained by the piston ring 10. [

In this embodiment, in addition to the piston ring 10, three piston rings 60, 70, and 80 are disposed at intervals in the direction along the axis CL (hereinafter also referred to as axial direction) Respectively. The piston ring 10 is disposed closest to the combustion chamber 5 in the axial direction. The total number of piston rings is not limited to four, but may be three, for example.

Fig. 2 is a perspective view schematically showing the piston ring 10. Fig. 2, the piston ring 10 includes a body portion 10a and a first tongue portion 12 and a second tongue portion 13 which form a joint portion 11. [

The main body portion 10a extends along the circumferential direction around the axis CL.

Fig. 3 is a plan view schematically showing an area A in Fig. 2, and Fig. 4 is a perspective view schematically showing an area A in Fig.

As shown in Figs. 3 and 4, the first tongue portion 12 extends from one end of the main body portion 10a in the circumferential direction. The first tongue portion 12 has an inner peripheral portion 12a forming an inner peripheral side of the piston ring 10 and an inner peripheral portion 12b extending from the combustion chamber 5 side in the axial direction of the inner peripheral edge 12a, And a contact piece 12b projecting outward in the direction. The inner peripheral piece 12a and the abutting piece 12b have L-shaped cross sections in cross section perpendicular to the circumferential direction and form fitting grooves 12c extending in the circumferential direction. The fitting groove 12c is located radially outward of the main body portion 10a and is located on the crosshead side (crank chamber side) in the axial direction.

The second tongue portion 13 extends from the other end of the main body portion 10a in the circumferential direction. The cross section of the second tongue portion 13 is formed in a rectangular shape in a cross section orthogonal to the circumferential direction and the second tongue portion 13 is formed on the outer surface of the inner circumferential piece 12a in the radial direction, And two side surfaces opposed to the surfaces on the side of the axial head of the crosshead. The first tongue portion 12 and the second tongue portion 13 are fitted into the fitting groove 12c in the state where the piston ring 10 is mounted on the piston 3, Shaped concave portion 11 is formed. The outer circumferential surface of the piston ring 10 is formed by the side surface 12d of the first tongue portion 12 and the side surface 13d of the second tongue portion 13. In the fitting portion 11, The side surface 12d of the first tongue portion 12 is the side surface of the abutting piece 12b.

The side surface 12d of the first tongue portion 12 is located on the outer side in the radial direction of the main body portion 10a and is directed radially outward. The side surface 12d extends along the circumferential direction and opposes the inner circumferential surface 2a of the cylinder when the piston ring 10 is mounted on the piston 3. [ Hereinafter, the side surface 12d of the first tongue portion 12 is also referred to as an outer circumferential surface 12d. The outer circumferential surface 12d of the first tongue portion 12 is the side surface of the abutting piece 12b.

Similarly, the side surface 13d of the second tongue portion 13 is located on the outer side in the radial direction of the main body portion 10a, and is directed radially outward. The side face 13d extends along the circumferential direction and faces the inner circumferential surface 2a of the cylinder when the piston ring 10 is mounted on the piston 3. [ Hereinafter, the side surface 13d of the second tongue portion 13 is also referred to as an outer circumferential surface 13d.

The end surface 10b of the one end side of the main body portion 10a and the end surface 10b of the second tongue portion 13 in the state in which the second tongue portion 13 is fitted in the fitting groove 12c of the first tongue portion 12, The front end face 13f and the front end face 12f of the first tongue portion 12 and the end face 10c of the other end side of the main body portion 10a face each other with a gap therebetween. These gaps can absorb the extension in the circumferential direction even if the piston ring 10 is expanded by the heat of the combustion gas in the combustion chamber 5 and the piston ring 10 is extended in the circumferential direction.

By forming such a gap between the end surface 10b of the body portion 10a and the tip end surface 13f of the second tongue portion 13, the first tongue portion 12 and the second tongue portion 13 overlap with each other in the axial direction are present in the vicinity of the root of the first tongue 12. A communicating groove G1 is formed on the outer peripheral surface 12d of the first tongue portion 12, that is, on the outer peripheral surface of the abutting piece 12b in the non-overlapping region S1. The communicating groove G1 extends in the axial direction and is open at both sides of the abutting piece 12b of the first tongue portion 12 in the axial direction. Therefore, the communication groove G1 communicates the combustion chamber 5 side with the crankcase side in the axial direction. The communication groove G1 also opens outward in the radial direction.

During operation of the engine 1, the piston ring 10 becomes hot due to being heated by the combustion gas. At this time, since the outer circumferential side of the piston ring 10 is in sliding contact with the relatively low-temperature cylinder inner circumferential surface 2a, the temperature of the inner circumferential side of the piston ring 10 becomes higher than the temperature of the outer circumferential side. The thermal expansion amount of the piston ring 10 is larger on the inner circumferential side than on the outer circumferential side and thermally deformed such that the merging portion 11 of the piston ring 10 bulges outward in the radial direction of the piston ring 10.

Such a thermal deformation increases the contact surface pressure between the first tongue portion 12 and the second tongue portion 13 constituting the merging portion 11 and the inner circumferential surface 2a of the cylinder, 2a. The radii of curvature of the first tongue portion 12 and the second tongue portion 13 are equal to the radii of curvature of the first tongue portion 12 and the second tongue portion 13, The radius of curvature of the inner circumferential surface 2a becomes larger and the base side of the first tongue portion 12 and the second tongue portion 13 becomes easier to fall off the inner circumferential surface 2a of the cylinder.

Therefore, when an uneven wear occurs in the cylinder inner circumferential surface 2a due to thermal deformation, a slight clearance delta 1 (? 1) between the base side of the thermally deformed first tongue portion 12 and the second tongue portion 13 and the cylinder inner circumferential surface 2a 2) may occur (see Fig. 3). In the case where the communication groove G1 is not formed, the high-temperature combustion gas is introduced into the vicinity of the root of the first tongue portion 12, that is, the non-overlapping region in which the first tongue portion 12 and the second tongue portion 13 do not overlap each other (S1), the slight gap (? 1) that has occurred exits from the combustion chamber (5) side to the crosshead side at high pressure and high speed. This blowing of the combustion gas causes a problem that the outer circumferential surface of the piston ring 10 is damaged in the non-overlapping region S1.

On the other hand, according to the above-described configuration, the communication grooves G1 are formed in advance in the outer peripheral surface 12d of the first tongue portion 12 in the non-overlapping region S1 in advance, And it is possible to prevent the high temperature combustion gas from escaping at high pressure and high speed in the non-overlapping region S1. As a result, the damage in the non-overlapping area S1 is suppressed, and the durability of the piston ring 10 is improved.

Further, by forming the communication groove G1, the rigidity of the first tongue portion 12 is reduced, and the contact surface pressure of the piston ring 10 with respect to the cylinder inner circumferential surface 2a is made uniform. As a result, uneven wear of the piston ring 10 and the cylinder inner circumferential surface 2a is suppressed, and the durability of the piston ring 10 is improved.

In the present embodiment, the cross-sectional shape of the communication groove G1 in the cross section orthogonal to the axis CL is formed in a semicircular shape. According to this configuration, the cross-sectional shape of the communication groove G1 in the cross section orthogonal to the axial line CL is made semicircular, so that the change in the cross-sectional shape near the communication groove G1 becomes smooth. As a result, stress concentration in the vicinity of the communication groove (G1) is alleviated, and durability of the piston ring (10) can be improved.

(Second Embodiment)

Hereinafter, the piston ring 20 according to the second embodiment of the present invention will be described. In the following description of the embodiments, the same or similar components as in the above-described embodiment are denoted by the same names or reference numerals, and the description thereof is omitted or simplified.

5 is a perspective view schematically showing a part of the piston ring 20 in an enlarged manner. In the piston ring 20, in the non-overlapping region S2 near the root of the second tongue portion 13 in which the first tongue portion 12 and the second tongue portion 13 do not overlap each other in the axial direction, the second tongue portion 13 And the communicating groove G2 is formed in the outer peripheral surface 13d of the outer peripheral surface 13d.

The communication grooves G2 extend in the axial direction and are open at both sides of the second tongue portion 13 in the axial direction. The communicating groove G2 is opened outward in the radial direction of the main body portion 10a.

According to this configuration, by forming the communication groove G2 in advance in the outer peripheral surface 13d of the second tongue portion 13 in the non-overlapping region S2 in advance, the combustion gas can be emitted through the communication groove G2, It is suppressed that the high temperature combustion gas escapes at high pressure and high speed in the non-overlapping region S2. As a result, the damage in the non-overlapping region S2 is suppressed, and the durability of the piston ring 20 is improved.

By forming the communication groove G2, the rigidity of the second tongue portion 13 is reduced, and the contact surface pressure of the piston ring 20 with respect to the cylinder inner circumferential surface 2a is made uniform. As a result, uneven wear of the piston ring 20 and the cylinder inner circumferential surface 2a is suppressed, and the durability of the piston ring 20 is improved.

In the present embodiment, the cross-sectional shape of the communication groove G2 in the cross section orthogonal to the axis CL is formed in a semicircular shape. According to this configuration, the cross-sectional shape of the communication groove G2 in the cross section orthogonal to the axial line CL is made semicircular, so that the change in the cross-sectional shape near the communication groove G2 is smooth. As a result, stress concentration in the vicinity of the communication groove (G2) is relaxed, and durability of the piston ring (20) can be improved.

(Third Embodiment)

Hereinafter, the piston ring 30 according to the third embodiment of the present invention will be described.

6 is a perspective view schematically showing a part of the piston ring 30 in an enlarged manner. In the piston ring 30, the outer circumferential surface 12d of the first tongue portion 12 and the outer circumferential surface 12c of the first tongue portion 12 in the non-overlapping regions S1, S2 where the first tongue portion 12 and the second tongue portion 13 do not overlap each other in the axial direction, The second embodiment differs from the first and second embodiments in that the communication grooves G1 and G2 are formed in the outer peripheral surface 13d of the two tongue portions 13. [

According to this configuration, the communication grooves G1 and G2 are formed in both the outer peripheral surface 12d of the first tongue portion 12 and the outer peripheral surface 13d of the second tongue portion 13 in the non-overlapping regions S1 and S2 , High-speed and high-pressure blowing of the high-temperature combustion gas in these two non-overlapping regions (S1, S2) is suppressed, and the damage of the piston ring (30) can be further prevented.

(Fourth Embodiment)

Hereinafter, the piston ring 40 according to the fourth embodiment of the present invention will be described.

7 is an enlarged perspective view schematically showing a part of the piston ring 40. As shown in Fig. 7, the cross-sectional area of the communication grooves G3 and G4 in the cross section perpendicular to the axis CL (the communication grooves G3 and G4 in the radial direction of the main body portion 10a) Is increased from one side in the direction along the axis CL toward the other side.

The communication grooves G3 and G4 extend in the axial direction and are respectively opened at both sides of the abutment piece 12b and the second tongue portion 13 of the first tongue portion 12 in the axial direction. The communication grooves G3 and G4 are opened outward in the radial direction of the main body portion 10a.

According to this configuration, when the combustion gas flows from one side to the other side by increasing the cross-sectional area of the communication grooves G3, G4 from one side toward the other side in the direction along the axis CL, The speed of the combustion gas flowing out from the other side of the communication grooves G3 and G4 can be lowered. For example, when the cross-sectional area of the communication grooves G3 and G4 increases from the combustion chamber 5 side toward the crosshead side (crank chamber) so that fuel flows from the combustion chamber 5 side toward the crankcase side, The speed of the combustion gas flowing out from the crosshead side of the gates G3 and G4 can be lowered.

Therefore, when another piston ring 60 is disposed on the side of the piston ring 10, for example, on the crank chamber side as shown in Fig. 1, the collision pressure of the combustion gas on the other piston ring 60 is reduced And the durability of the other piston ring 60 is improved.

The present invention is not limited to the above-described first to fourth embodiments, but includes modifications to these embodiments and combinations of these embodiments.

For example, the cross-sectional shape of the communication grooves G1 and G2 is preferably a semicircular shape, but may be a V-shape or a rectangular shape.

It is needless to say that the piston ring according to the present invention is suitable for a marine two-cycle large diesel engine, but may be applied to other engines.

1: engine
2: Cylinder
2a: inner circumferential surface of the cylinder
3: Piston
3a: Piston rod
4: Cylinder head
5: Combustion chamber
6: Piston ring groove
10: Piston ring
10a:
10b: section
10c: section
11:
12: First tongue
12a:
12b:
12c: fitting groove
12d: outer peripheral surface
12f:
13: 2nd tongue
13d: outer peripheral surface
13f:
G1, G2, G3, G4: communicating groove
S1, S2: Non-overlapping area
δ1, δ2: Clearance

Claims (6)

A body portion extending along a circumferential direction around the axis,
A first tongue portion extending from one end of the body portion to the other end and having a fitting groove extending radially outwardly of the body portion and extending along the circumferential direction on one side in the axial direction;
A second tongue portion extending from the other end of the body portion to the one end and forming a joint portion together with the first tongue portion by fitting into the fitting groove;
And a communicating groove formed in at least one of an outer peripheral surface of the first tongue portion and an outer peripheral surface of the second tongue portion in a non-overlapping region where the first tongue portion and the second tongue portion do not overlap with each other, . The method according to claim 1,
Wherein the communication groove is formed on both the outer circumferential surface of the first tongue portion and the outer circumferential surface of the second tongue portion. 3. The method according to claim 1 or 2,
Wherein the cross-section of the communication groove in the radial direction is a semicircular shape. 3. The method according to claim 1 or 2,
Wherein the cross-sectional area of the communication groove in the radial direction is increased from one side in the axial direction toward the other side. An engine comprising the piston ring according to claim 1. 6. The method of claim 5,
Wherein the cross-sectional area of the communication groove in the radial direction is increased from the combustion chamber side toward the crank chamber side in the axial direction.

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