JP2015158247A - Piston ring and engine equipped with piston ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas-tight piston ring capable of suppressing combustion gas from being blown at high pressure and at high speed through a non-overlap region where a first tongue part and a second tongue part do not overlap each other and improving durability, and an engine equipped with the piston ring.SOLUTION: A piston ring 10 comprises: a body part; a first tongue part 12 extending from one end to the other end of the body part, and including a fitting groove 12c formed therein to extend along a circumferential direction to one side in an axial direction and radially outward of the body part; a second tongue part 13 extending from the other end to one end of the body part, and fitting into the fitting groove 12c to form an abutment part 11 between the first tongue part 12 and the second tongue part 13; and a communication groove G1 provided in at least either an outer circumferential surface 12d of the first tongue part 12 or an outer circumferential surface 13d of the second tongue part 13 in a non-overlap region S1 where the first tongue section 12 does not overlap the second tongue part 13 in a direction along an axis, and communicating in the axial direction.

Description

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

  The piston ring is mounted in a piston ring groove formed on 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 cylinder inner peripheral surface, and the cylinder head by sliding and contacting the inner peripheral surface of the cylinder with an appropriate surface pressure. .

  The piston ring has a ring shape, but a discontinuous portion called a joint portion is provided in a part of the circumferential direction. For example, a gas tight type abutment as described in Patent Document 1 is composed of a concave portion provided on one end side in the circumferential direction of the piston ring and a convex portion provided on the other end side. It is made to fit so that it may overlap.

JP-A-7-332496

  During engine operation, the piston ring is heated by the combustion gas and becomes hot. 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 on the inner peripheral side of the piston ring is higher than the temperature on the outer peripheral side. For this reason, the amount of thermal expansion of the piston ring is larger on the inner peripheral side than on the outer peripheral side, so that the joint portion of the piston ring is thermally deformed so as to expand outward in the radial direction of the piston ring.

  Due to such thermal deformation, the contact surface pressure between the concave portion (first tongue portion) and the convex portion (second tongue portion) constituting the abutment portion and the cylinder inner peripheral surface increases, and the cylinder inner peripheral surface near the abutment portion. Cause uneven wear. On the other hand, when the first tongue portion and the second tongue portion try to swell radially outward due to thermal deformation, the curvature radius of the first tongue portion and the second tongue portion becomes the curvature radius of the cylinder inner peripheral surface. The base side of the first tongue and the second tongue is easily separated from the cylinder inner peripheral surface.

  For this reason, when uneven wear occurs on the inner peripheral surface of the cylinder due to thermal deformation, there is a slight gap between the base side of the first and second tongue portions that are thermally deformed and the inner peripheral surface of the cylinder. May occur. Then, the high-temperature combustion gas is slightly generated in the vicinity of the roots of the first tongue and the second tongue, in other words, in the region where the first tongue and the second tongue do not overlap (non-overlapping region). A large gap is blown from the combustion chamber side to the crank chamber side at high pressure and high speed. Due to the blow-off of the combustion gas, there arises a problem that the outer peripheral surface of the piston ring is damaged in the non-overlapping region.

  The present invention has been made in order to solve the above problems, and is a gas tight type piston in which the high-pressure and high-speed blow-off of the combustion gas in the non-overlapping region of the first tongue and the second tongue is suppressed, and the durability is improved. An object is to provide a ring and an engine including the piston ring.

In order to solve the above problems, the piston ring according to the present invention is:
A main body extending along the circumferential direction around the axis;
A first tongue portion extending from one end of the main body portion to the other end and having a fitting groove extending radially outward of the main body portion and extending along the circumferential direction on one side in the axial direction. When,
A second tongue portion extending from the other end of the main body portion to the one end and forming a joint portion with the first tongue portion by fitting into the fitting groove;
Provided in at least one of the outer peripheral surface of the first tongue and the outer peripheral surface of the second tongue in a non-overlapping region where the first tongue and the second tongue do not overlap, and in the axial direction A communication groove that communicates,
Is provided.

According to this configuration, in the non-overlapping region, the communication groove is positively provided in advance in at least one of the outer peripheral surface of the first tongue and the outer peripheral surface of the second tongue, so that the combustion gas escapes through the communication groove. It is possible to suppress the high-temperature combustion gas from blowing through at high pressure and high speed in the non-overlapping region. As a result, damage in the non-overlapping region is suppressed, and the durability of the piston ring is improved.
Further, by providing 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 peripheral surface is made uniform. As a result, uneven wear of the piston ring and the cylinder inner peripheral surface 2a is suppressed, and the durability of the piston ring is improved.

In some embodiments,
The communication groove is provided on both the outer peripheral surface of the first tongue and the outer peripheral surface of the second tongue.
According to this configuration, by providing the communication grooves on both the outer peripheral surface of the first tongue and the outer peripheral surface of the second tongue in the non-overlapping region, the high-temperature combustion gas in these two non-overlapping regions High-speed and high-pressure blow-through is suppressed, and damage to 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 communication groove in the vicinity of the communication groove becomes smooth by making the cross-sectional shape of the communication groove in the cross section orthogonal to the axis line a semicircular shape. As a result, stress concentration in the vicinity of the communication groove is alleviated, 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 axis, The speed of the combustion gas flowing out from the other side of the groove can be reduced. For this reason, when another piston ring is arrange | positioned next to a piston ring, the collision pressure of the combustion gas to another piston ring can be reduced, and durability of another piston ring improves.

The engine according to the present invention includes any one of the above-described piston rings.
According to this configuration, in the piston ring, the high-pressure and high-speed blow-off of the combustion gas in the non-overlapping region of the first tongue and the second tongue is suppressed, and the durability of the piston ring is improved. Engine durability is also improved.

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 is about to flow 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.
For this reason, when the other piston ring is arrange | positioned at the crank chamber side of a piston ring, the collision pressure of the combustion gas to another piston ring can be reduced, and durability of other piston rings improves.

  According to the present invention, there is provided a gas tight type piston ring in which the high-pressure and high-speed blow-off of the combustion gas in the non-overlapping region between the first tongue and the second tongue is suppressed, and the durability is improved. An engine is provided.

1 is a schematic cross-sectional view of an engine to which a piston ring according to the present invention is applied. It is a perspective view showing the outline appearance of the piston ring concerning a 1st embodiment of the present invention. FIG. 3 is a plan view schematically showing an enlarged region A of FIG. 2 together with a part of a cylinder. FIG. 3 is a perspective view schematically showing an enlarged area A in FIG. 2. It is a perspective view equivalent to FIG. 4 of the piston ring which concerns on 2nd Embodiment of this invention. It is a perspective view equivalent to FIG. 4 of the piston ring which concerns on 3rd Embodiment of this invention. It is a perspective view equivalent to FIG. 4 of the piston ring which concerns on 4th Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

(First embodiment)
FIG. 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 marine 2-cycle large diesel engine.
The engine 1 includes a cylinder 2, a piston 3 that is reciprocally disposed in the cylinder 2, and a cylinder head 4 that covers one end of the cylinder 2. On one end side of the cylinder 2, a combustion chamber 5 is defined by the cylinder 2, the piston 3 and the cylinder head 4.

  The engine 1 has, for example, a crosshead structure, and a piston rod 3 a extends from the opposite side of the piston 3 to the combustion chamber 5, and the piston rod 3 a penetrates the other end side of the cylinder 2. Although not shown, the opposite side of the piston rod 3a to the piston 3 is connected to a crankshaft in the crank chamber via a crosshead and a connecting rod. When the engine 1 is of a uniflow scavenging type, for example, an exhaust port is provided in the cylinder head 4 and a scavenging port (not shown) is provided on the other end side of the cylinder 2.

  The piston ring 10 is attached to the outer periphery of the piston 3. Specifically, a piston ring groove 6 is formed on 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 line CL of the piston ring 10 coincides with the axis line of the cylinder 2 and the piston 3.

  The piston ring 10 protrudes outward from the outer peripheral surface of the piston 3 in the radial direction of the piston 3, and has an outer peripheral surface that is in sliding contact with the inner peripheral surface (cylinder inner peripheral surface) 2 a of the cylinder 2. Therefore, the gap between the cylinder inner peripheral surface 2 a and the outer peripheral surface of the piston 3 is closed by the piston ring 10, and the pressure of the combustion chamber 5 can be held by the piston ring 10.

  In the present embodiment, in addition to the piston ring 10, three piston rings 60, 70, and 80 are attached to the piston 3 with an interval in the direction along the axis line CL (hereinafter also referred to as the axial direction). Yes. 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, and may be three, for example.

FIG. 2 is a perspective view schematically showing the piston ring 10. As shown in FIG. 2, the piston ring 10 includes a main body portion 10 a, and a first tongue portion 12 and a second tongue portion 13 that form the joint portion 11.
The main body 10a extends along the circumferential direction around the axis CL.

3 is a plan view schematically showing a region A in FIG. 2, and FIG. 4 is a perspective view schematically showing the region A in FIG.
As shown in FIGS. 3 and 4, the first tongue portion 12 extends from one end of the main body portion 10 a in the circumferential direction. The first tongue 12 includes an inner peripheral piece 12a that forms the inner peripheral side of the piston ring 10, and a contact piece that protrudes radially outward from the combustion chamber 5 side in the axial direction of the inner peripheral piece 12a. 12b. The inner peripheral piece 12a and the contact piece 12b have an L-shaped cross-sectional shape in a cross section orthogonal to the circumferential direction, and form a fitting groove 12c extending in the circumferential direction. The fitting groove 12c is located on the outer side in the radial direction of the main body 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. In the cross section orthogonal to the circumferential direction, the cross-sectional shape of the second tongue portion 13 is formed in a rectangular shape, and the second tongue portion 13 includes the radial outer surface of the inner peripheral piece 12a and the axial cross of the contact piece 12b. It has two side surfaces respectively facing the head side surface. In a state where the piston ring 10 is mounted on the piston 3, the first tongue portion 12 and the second tongue portion 13 form the gas tight type abutment portion 11 by fitting the second tongue portion 13 into the fitting groove 12c. To do. In the joint portion 11, the outer peripheral surface of the piston ring 10 is formed by the side surface 12 d of the first tongue portion 12 and the side surface 13 d of the second tongue portion 13. The side surface 12d of the first tongue portion 12 is the side surface of the contact piece 12b.

  The side surface 12d of the first tongue portion 12 is located outside in the radial direction of the main body portion 10a and faces outward in the radial direction. The side surface 12d extends along the circumferential direction, and is opposed to the cylinder inner circumferential surface 2a 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 peripheral surface 12d. The outer peripheral surface 12d of the first tongue 12 is a side surface of the contact piece 12b.

  Similarly, the side surface 13d of the second tongue portion 13 is located outside in the radial direction of the main body portion 10a and faces outward in the radial direction. The side surface 13d extends along the circumferential direction, and is opposed to the cylinder inner circumferential surface 2a 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 peripheral surface 13d.

  In a state where the second tongue portion 13 is fitted in the fitting groove 12 c of the first tongue portion 12, the end surface 10 b on one end side of the main body portion 10 a, the tip surface 13 f of the second tongue portion 13, and the first tongue portion 12. The front end surface 12f and the end surface 10c on the other end side of the main body 10a face each other with a gap therebetween. Even if the piston ring 10 expands due to the heat of the combustion gas in the combustion chamber 5 and the piston ring 10 extends in the circumferential direction, the circumferential expansion can be absorbed by these gaps.

  By providing such a gap between the end surface 10b of the main body portion 10a and the front end surface 13f of the second tongue portion 13, the first tongue portion 12 and the second tongue portion 13 are disposed in the axial direction at the joint portion 11. A non-overlapping region S1 that does not overlap with the first tongue 12 is present in the vicinity of the root of the first tongue 12. A communication groove G1 is formed on the outer peripheral surface 12d of the first tongue 12 in the non-overlapping region S1, that is, on the outer peripheral surface of the contact piece 12b. The communication groove G1 extends in the axial direction and opens on both sides of the contact piece 12b of the first tongue portion 12 in the axial direction. Therefore, the communication groove G1 communicates the combustion chamber 5 side and the crank chamber side in the axial direction. Further, the communication groove G1 opens outward in the radial direction.

  During the operation of the engine 1, the piston ring 10 is heated by the combustion gas and becomes high temperature. At this time, since the outer peripheral side of the piston ring 10 is in sliding contact with the relatively low temperature inner peripheral surface 2a of the cylinder, the temperature on the inner peripheral side of the piston ring 10 becomes higher than the temperature on the outer peripheral side. For this reason, the amount of thermal expansion of the piston ring 10 is larger on the inner peripheral side than on the outer peripheral side, and the joint portion 11 of the piston ring 10 is thermally deformed so as to expand outward in the radial direction of the piston ring 10.

  Due to such thermal deformation, the contact surface pressure between the first tongue portion 12 and the second tongue portion 13 constituting the joint portion 11 and the cylinder inner peripheral surface 2a is increased, and the cylinder inner peripheral surface 2a is formed in the vicinity of the joint portion 11. Uneven wear occurs. On the other hand, when the distal ends of the first tongue 12 and the second tongue 13 try to expand radially outward due to thermal deformation, the curvature radii of the first tongue 12 and the second tongue 13 are changed to the inner circumference of the cylinder. It becomes larger than the curvature radius of the surface 2a, and the base side of the first tongue portion 12 and the second tongue portion 13 is easily separated from the cylinder inner peripheral surface 2a.

  For this reason, when uneven wear occurs on the cylinder inner peripheral surface 2a due to thermal deformation, the base side of the thermally deformed first tongue 12 and second tongue 13 and the cylinder inner peripheral surface 2a are interposed between them. Slight gaps δ1 and δ2 may occur (see FIG. 3). When the communication groove G1 is not provided, the high-temperature combustion gas is near the root of the first tongue 12, in other words, in the non-overlapping region S1 where the first tongue 12 and the second tongue 13 do not overlap, The generated small gap δ1 is blown from the combustion chamber 5 side to the cross head side at high pressure and high speed. Such a blow-by of the combustion gas causes a problem that the outer peripheral surface of the piston ring 10 is damaged in the non-overlapping region S1.

On the other hand, according to the above-described configuration, by providing the communication groove G1 in advance in the outer peripheral surface 12d of the first tongue 12 in the non-overlapping region S1, the combustion gas can escape through the communication groove G1. It is possible to suppress high-temperature combustion gas from blowing through at high pressure and high speed in the non-overlapping region S1. As a result, damage in the non-overlapping region S1 is suppressed, and the durability of the piston ring 10 is improved.
Further, by providing the communication groove G1, the rigidity of the first tongue 12 is reduced, and the contact surface pressure of the piston ring 10 with respect to the cylinder inner peripheral surface 2a is made uniform. As a result, uneven wear of the piston ring 10 and the cylinder inner peripheral surface 2a is suppressed, and the durability of the piston ring 10 is improved.

  Furthermore, in this embodiment, the cross-sectional shape of the communication groove G1 in the cross section orthogonal to the axis line CL is formed in a semicircular shape. According to this configuration, by making the cross-sectional shape of the communication groove G1 in the cross section orthogonal to the axis CL a semicircular shape, the change in the cross-sectional shape near the communication groove G1 becomes smooth. As a result, the stress concentration in the vicinity of the communication groove G1 is relaxed, and the durability of the piston ring 10 can be improved.

(Second Embodiment)
Hereinafter, a piston ring 20 according to a second embodiment of the present invention will be described. In the following description of the embodiment, the same or similar configuration as that of the above-described embodiment is denoted by the same name or symbol, and the description is omitted or simplified.

FIG. 5 is a perspective view schematically showing an enlarged part of the piston ring 20. The piston ring 20 is formed on the outer peripheral surface 13d of the second tongue 13 in a non-overlapping region S2 near the root of the second tongue 13 where the first tongue 12 and the second tongue 13 do not overlap in the axial direction. The second embodiment is different from the first embodiment in that the communication groove G2 is formed.
The communication groove G2 extends in the axial direction and opens on both sides of the second tongue 13 in the axial direction. Further, the communication groove G2 opens outward in the radial direction of the main body portion 10a.

According to this configuration, by providing the communication groove G2 in advance in the outer peripheral surface 13d of the second tongue 13 in the non-overlapping region S2, the combustion gas can escape through the communication groove G2, and the non-overlapping region S2 In the region S2, the high-temperature combustion gas is suppressed from blowing through at high pressure and high speed. As a result, damage in the non-overlapping region S2 is suppressed, and the durability of the piston ring 20 is improved.
Further, by providing 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 peripheral surface 2a is made uniform. As a result, uneven wear of the piston ring 20 and the cylinder inner peripheral surface 2a is suppressed, and the durability of the piston ring 20 is improved.

  Furthermore, in this embodiment, the cross-sectional shape of the communication groove G2 in the cross section orthogonal to the axis line CL is formed in a semicircular shape. According to this configuration, by changing the cross-sectional shape of the communication groove G2 in the cross section orthogonal to the axis CL to a semicircular shape, the change in the cross-sectional shape near the communication groove G2 becomes smooth. As a result, stress concentration in the vicinity of the communication groove G2 is alleviated, and the durability of the piston ring 20 can be improved.

(Third embodiment)
Hereinafter, a piston ring 30 according to a third embodiment of the present invention will be described.
FIG. 6 is a perspective view schematically showing an enlarged part of the piston ring 30. The piston ring 30 has an outer peripheral surface 12d of the first tongue 12 and an outer periphery of the second tongue 13 in the non-overlapping regions S1 and S2 where the first tongue 12 and the second tongue 13 do not overlap in the axial direction. The first and second embodiments are different in that communication grooves G1 and G2 are formed on the surface 13d.

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

(Fourth embodiment)
Hereinafter, a piston ring 40 according to a fourth embodiment of the present invention will be described.
FIG. 7 is an enlarged perspective view schematically showing a part of the piston ring 40. In the present embodiment, as shown in FIG. 7, the cross-sectional area of the communication grooves G3 and G4 in the cross section orthogonal to the axis CL (the cross-sectional area of the communication grooves G3 and G4 in the radial direction of the main body 10a) is the axis CL. In one direction from the one side to the other side.
The communication grooves G3 and G4 extend in the axial direction, and open on both sides of the contact piece 12b of the first tongue portion 12 and the second tongue portion 13 in the axial direction. The communication grooves G3 and G4 are opened outward in the radial direction of the main body 10a.

According to this configuration, the cross-sectional area of the communication grooves G3 and G4 increases from one side to the other side in the direction along the axis CL, so that the combustion gas flows from one side to the other side. When flowing, the speed of the combustion gas flowing out from the other side of the communication grooves G3, G4 can be reduced. For example, when the cross-sectional area of the communication grooves G3 and G4 increases from the combustion chamber 5 side to the crosshead side (crank chamber), fuel flows from the combustion chamber 5 side to the crank chamber side. The speed of the combustion gas flowing out from the crosshead side of G3 and G4 can be reduced.
Therefore, as shown in FIG. 1, when another piston ring 60 is arranged next to the piston ring 10, for example, on the crank chamber side, the collision pressure of the combustion gas to the other piston ring 60 can be reduced. The durability of the piston ring 60 is improved.

The present invention is not limited to the first to fourth embodiments described above, and includes forms obtained by modifying these embodiments and forms obtained by combining these embodiments.
For example, the cross-sectional shape of the communication grooves G1, G2 is preferably a semicircular shape, but may be a V shape, a rectangular shape, or the like.
Moreover, although the piston ring which concerns on this invention is suitable for a marine 2-cycle large-sized diesel engine, of course, you may apply to another engine etc.

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder 2a Cylinder inner peripheral surface 3 Piston 3a Piston rod 4 Cylinder head 5 Combustion chamber 6 Piston ring groove 10 Piston ring 10a Main body part 10b End surface 10c End surface 11 Joint part 12 First tongue part 12a Inner peripheral piece 12b Contact piece 12c Fitting groove 12d Outer peripheral surface 12f Front end surface 13 Second tongue 13d Outer peripheral surface 13f Front end surface G1, G2, G3, G4 Communication grooves S1, S2 Non-overlapping regions δ1, δ2 Gap

Claims (6)

A main body extending along the circumferential direction around the axis;
A first tongue portion extending from one end of the main body portion to the other end and having a fitting groove extending radially outward of the main body portion and extending along the circumferential direction on one side in the axial direction. When,
A second tongue portion extending from the other end of the main body portion to the one end and forming a joint portion with the first tongue portion by fitting into the fitting groove;
Provided in at least one of the outer peripheral surface of the first tongue and the outer peripheral surface of the second tongue in a non-overlapping region where the first tongue and the second tongue do not overlap, and in the axial direction A communication groove that communicates,
A piston ring comprising:   The piston ring according to claim 1, wherein the communication groove is provided on both an outer peripheral surface of the first tongue portion and an outer peripheral surface of the second tongue portion.   3. The piston ring according to claim 1, wherein a cross-section of the communication groove in the radial direction is a semicircular shape.   4. The piston ring according to claim 1, wherein a cross-sectional area of the communication groove in the radial direction increases from one side to the other side in the axial direction. 5. .   An engine comprising the piston ring according to any one of claims 1 to 4.   The engine according to claim 5, wherein a cross-sectional area of the communication groove in the radial direction increases from the combustion chamber side to the crank chamber side in the axial direction.

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