JP5077798B2 - Piston ring of reciprocating engine - Google Patents

Description

  The present invention relates to a piston ring of a reciprocating engine that realizes improvement in sliding contact with an inner peripheral surface and reduction in wear on an outer peripheral surface that is in sliding contact with an inner peripheral surface of an engine cylinder liner.

6A is a schematic cross-sectional view around a piston of a large diesel engine (showing one side cross-section of the piston), FIG. 6B is an enlarged view of a Z portion in FIG. 6A, and FIG. It is a perspective view shown.
In FIG. 6 (A), the piston 2 is configured by connecting an inner peripheral piston central portion 2a and an outer peripheral cylindrical portion 2b.
A plurality of piston rings 1 are fitted into the ring grooves 3 formed in a plurality of stages in the height direction of the outer peripheral cylindrical portion 2b. The piston 2 reciprocates while the outer peripheral surface 1 c of the piston ring 1 is in sliding contact with the sliding surface 6 a of the cylinder liner 6. A ring side surface gap 7 that opens to the combustion chamber 4 of the engine is formed on the side of the outer peripheral cylindrical portion 2b of the piston 2, and the ring side surface gap 7 is filled with combustion gas from the combustion chamber 4. ing.
As shown in FIG. 6B, the piston ring 1 includes the outer peripheral surface 1c, an upper surface 1a perpendicular to the direction of the axis 100 of the piston 2 that contacts the gas in the combustion chamber 4, and the opposite side of the upper surface 1a. The lower surface 1b formed in this and the inner ring back surface 1d are connected.

When the piston 2 of the engine is raised, an upper gap 3a and a back gap 3b are formed in the piston ring 1, and combustion from the combustion chamber 4 side from the ring side face gap 7 is formed in the upper gap 3a and the back gap 3b. Gas is flowing in as shown by the arrow.
Further, as shown in FIG. 6 (C), the piston ring 1 is notched at the mating portion, and is connected in a ring shape via the notched mating portion 1e.

As described above, the piston ring 1 is exposed to different gas pressures on the upper surface 1a and the lower surface 1b of the ring, and the high-pressure combustion gas is generated in the abutment portion 1e, the sliding surface 6a, the upper gap 3a, and the back gap 3b. Leaks to the low pressure side where the lower surface 1b faces. The main leak is a leak from the abutment portion 1e.
As a means for preventing gas leakage from the mating portion 1e, etc., improving the oil retaining property of the outer peripheral surface 1c sliding while making sliding contact with the sliding surface 6a of the cylinder liner 6, and maintaining the sealing performance, FIG. The means shown in 7 is provided.
In FIG. 7, a plurality of grooves 10s are formed on the outer peripheral surface 1c at equal intervals along the direction of the axis 100 of the piston 2 of the outer peripheral surface 1c. In FIG. 7, the configuration other than the groove 10s is the same as in FIG. 6B, and the same members are denoted by the same reference numerals.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 2000-129492) discloses a porous chrome plating layer having a large number of cavities open to the surface on the outer peripheral surface, and silicon nitride particle dispersion formed on the porous chrome plating layer. It has a double-structured film composed of a nickel-cobalt-phosphorus alloy plating layer, and a large number of dimples formed by porous chrome plating are formed on the outer peripheral surface.

JP 2000-129492 A

  As described above, in the piston ring 1, high-pressure combustion gas leaks to the low-pressure side facing the lower surface 1b through the abutment portion 1e, the sliding surface 6a, the upper gap 3a, the back gap 3b, etc., and the main leak Since this is a leak from the mating portion 1e, it is possible to prevent gas leakage from the mating portion 1e and the like, and to retain oil on the outer peripheral surface 1c that slides while sliding on the sliding surface 6a of the cylinder liner 6 As a means for improving the performance and maintaining the sealing performance, the means shown in FIG. 7 is provided.

That is, in FIG. 7, a plurality of grooves 10 s are formed on the outer peripheral surface 1 c at equal intervals along the axial direction of the piston 2 on the outer peripheral surface 1 c.
However, in FIG. 7, since the plurality of grooves 10s are formed on the outer peripheral surface 1c at equal intervals, when the high-pressure combustion gas acts on the upper surface 1a side of the piston ring 1, the outer periphery of the sliding surface 6a. A portion of the surface 1c near the upper surface 1a is worn, and the cross section has a trapezoidal shape with a short upper base. For this reason, the plurality of grooves 10s aiming at oil retaining properties disappear first from the wear site where oil is desired to be retained.

  If the hardness of the outer peripheral surface 1c is increased in order to deal with such a problem, not only the formation of the plurality of grooves 10s becomes difficult, but the shape of the piston ring 1 is not adapted to an appropriate shape. The contact pressure to the cylinder liner 6 is kept high, leading to excessive wear of the cylinder liner 6.

  In view of the problems of the prior art, the present invention has a very simple structure, improves the shape of the outer peripheral surface of the piston ring, and quickly reaches a predetermined familiar shape while keeping the oil retaining property of the sliding outer peripheral surface of the piston ring. It is an object of the present invention to provide a piston ring for a reciprocating engine that prevents seizure of the piston ring and occurrence of abnormal wear on the sliding outer peripheral surface.

The present invention solves such a problem, and is connected to the upper surface contacting gas on the combustion chamber side perpendicular to the axial direction of the piston, the lower surface formed on the opposite side of the upper surface, and the upper surface and the lower surface, respectively. In the piston ring of a reciprocating engine having an outer peripheral surface formed in the axial direction of the cylinder liner and in contact with the sliding surface of the cylinder liner,
A plurality of grooves are engraved on the outer peripheral surface along the axial direction of the piston on the outer peripheral surface, and the plurality of grooves have a large groove size and a gap between the grooves at a certain length from the upper surface side. A large number of large grooves having a small distance are formed, and a portion closer to the lower surface than the predetermined length is formed as a small groove having a groove size smaller than that of the large grooves and having a large distance between the grooves ( Claim 1).

  In the invention, it is preferable that the plurality of grooves are formed by continuously reducing the shape of the grooves in the axial direction of the piston from the upper surface side from the large grooves having a large groove size. It connects with the said small groove smaller than a groove | channel (Claim 2).

  In the piston ring of the reciprocating engine according to the present invention, a plurality of grooves having the same shape are formed on the outer peripheral surface along the axial direction of the piston on the outer peripheral surface, and the plurality of grooves are formed on the upper surface. A certain length from the side is formed in a large number of grooves with a small axial pitch of the piston and a large number of grooves, and the portion closer to the lower surface than the certain length has a smaller pitch and a smaller number of grooves than the small pitch. It is formed in the groove | channel (Claim 3).

  In this invention, it is preferable that the plurality of grooves having the same shape reduce the number of grooves by continuously reducing the axial pitch of the piston from the upper surface side from the number of the plurality of grooves. And connecting to the small number of grooves (claim 4).

In the piston ring of the reciprocating engine according to the present invention, the outer peripheral surface has a rough finish surface along the outer peripheral surface from the upper surface side in the axial direction of the piston in a certain length, and the surface is more than the predetermined length. The portion near the lower surface is configured to have a smoother finished surface than the rough finished surface (Claim 5).
In this invention, preferably, the rough finished surface is ground by a grinder, and the smooth finished surface is formed by etching.

  In the piston ring of the reciprocating engine according to the present invention, a plurality of dimples by shot peening are engraved on the outer peripheral surface along the outer peripheral surface, and the plurality of dimples have a predetermined length from the upper surface side. The piston is formed in a large number of dimples with a small axial pitch and a large number of dimples, and the portion closer to the bottom surface than the fixed length is formed in a small number of dimples having a larger pitch than the small pitch and a small number of dimples. (Claim 7).

According to the present invention, the plurality of grooves provided along the axial direction of the piston on the outer peripheral surface that is in sliding contact with the sliding surface of the cylinder liner have a groove size of a certain length from the upper surface side. A large number of large grooves with a small distance between the grooves are formed, and a portion closer to the lower surface than the predetermined length is formed into a small groove having a groove size smaller than that of the large grooves and with a large distance between the grooves. (Claim 1),
When the high-pressure combustion gas acts on the outer peripheral surface of the sliding surface from the upper surface side of the piston ring, the load on the outer peripheral surface becomes smaller as the upper surface side becomes larger and the lower surface side in the axial direction of the piston.
Therefore, according to this invention, the groove is formed in a large number of large grooves with a small length from the upper surface side and the distance between the grooves is small, and the portion closer to the lower surface than the predetermined length is the groove size. Is formed into a large number of large grooves at a certain length from the upper surface side during the progress of wear of the grooves, by forming the small grooves smaller than the large grooves and having a large distance between the grooves. The groove wear is less than that of the oil and the oil retention is improved.
Further, the portion closer to the lower surface than the predetermined length with less wear of the groove is a small groove having a small groove size and a large distance between the grooves, so that the oil retainability can be sufficiently maintained as usual.

In addition, since the groove size is large and the distance between the grooves is small at a certain length from the upper surface side, the portion closer to the lower surface than the certain length has a smaller groove size and a groove. By using small grooves with a large distance between them, the flexibility of the groove at a certain length from the upper surface side becomes larger than the portion closer to the lower surface than the certain length.
Therefore, when the high-pressure combustion gas acts on the outer peripheral surface of the sliding surface from the upper surface side of the piston ring, deformation of the upper portion of the piston ring is facilitated by the generation of the flexibility of the groove at a certain length from the upper surface side. This improves the familiarity and reduces the contact pressure between the piston ring and the cylinder liner.

In the invention, the plurality of grooves may be smaller than the large grooves by continuously reducing the shape of the grooves in the axial direction of the piston from the upper surface side from the large grooves having a large groove size. If configured to connect to the small small groove (Claim 2),
When the high-pressure combustion gas acts on the outer peripheral surface of the sliding surface from the upper surface side of the piston ring, the load on the outer peripheral surface decreases as the upper surface side becomes larger and the lower surface side in the axial direction of the piston. Therefore, in the present invention, the groove shape is continuously reduced in the axial direction of the piston from the upper surface side from the large groove having a plurality of large grooves so as to be connected to the small groove smaller than the large groove. By configuring, as the piston ring load becomes smaller as the upper surface side becomes larger and the lower surface side becomes smaller, the shape of the groove also slides and changes with the change of the piston ring load, and the appropriate shape according to the piston ring load Can provide the groove.

Further, according to the present invention, a plurality of grooves having the same shape on the outer peripheral surface are formed into a plurality of grooves having a small axial pitch of the piston and a large number of grooves when the fixed length is from the upper surface side. If the portion closer to the lower surface is formed in a small number of grooves having a larger pitch and a smaller number of grooves than the small pitch (Claim 3),
Even if the sizes of the plurality of grooves are the same, the pitch of the grooves is a large number of grooves that are small in length from the upper surface side and large in number of grooves, and the portion closer to the lower surface than the certain length has a pitch. By using a small number of grooves with a large number of grooves,
When groove wear progresses, the groove pitch is reduced and formed into a large number of grooves within a certain length from the upper surface side, so that groove wear is reduced and oil retention is improved compared to conventional ones. In addition, the portion closer to the lower surface than the predetermined length with less wear of the grooves can be sufficiently retained as usual by increasing the groove pitch to form a small number of grooves with a large distance between the grooves. .

In addition, according to this invention, in a certain length from the upper surface side, a plurality of grooves of the same shape are formed into a large number of grooves having a small axial pitch of the piston and a large number of grooves, and are closer to the lower surface than the certain length. By forming the part in a small number of grooves with a large pitch and a small number of grooves,
The flexibility of a large number of grooves at a certain length from the upper surface side is larger than a small number of grooves near the lower surface than the certain length, and high-pressure combustion gas flows from the upper surface side of the piston ring to the outer peripheral surface of the sliding surface. Due to the flexibility of a large number of grooves at a certain length from the upper surface side when acting on the piston ring, deformation of the piston ring is facilitated and conformability is improved, and the contact pressure between the piston ring and the cylinder liner is reduced.

In the invention, the plurality of grooves having the same shape may be formed by reducing the number of grooves by continuously decreasing the axial pitch of the piston from the upper surface side from a large number of grooves. If it is configured to be connected to a number (Claim 4),
When the high-pressure combustion gas acts on the outer peripheral surface of the sliding surface from the upper surface side of the piston ring, the load on the outer peripheral surface decreases as the upper surface side becomes larger and the lower surface side in the axial direction of the piston.
Therefore, in the present invention, even if the shape of the plurality of grooves is the same, the axial pitch of the piston from the upper surface side is continuously reduced from the large number of grooves, so that the small number of grooves It is linked to.
Thereby, as the piston ring load becomes smaller as the upper surface side becomes larger and the lower surface side becomes smaller, the axial pitch of the groove also slides and changes according to the change of the piston ring load. Properly shaped grooves can be provided.

In the present invention, the outer peripheral surface has a rough finish surface at a fixed length in the axial direction of the piston from the upper surface side along the outer peripheral surface, and a portion closer to the lower surface than the predetermined length is more than the rough finish surface. A smooth finished surface is formed (Claim 5), and preferably, the rough finished surface is ground by a grinder and the smooth finished surface is formed by etching (Claim 6).
When the high-pressure combustion gas acts on the outer peripheral surface of the sliding surface from the upper surface side of the piston ring, the load on the outer peripheral surface becomes smaller as the upper surface side becomes larger and the lower surface side in the axial direction of the piston.
Therefore, according to the present invention, a certain length from the upper surface side is a rough finish surface such as a grinding finish by a grinder, and a portion closer to the lower surface than the certain length is a smooth finish surface than a rough finish surface such as an etching finish. By configuring, when the wear of the piston ring progresses, the outer surface is less worn than the conventional one by forming a rough finish surface such as grinding finish by the grinder at a certain length from the upper surface side. Oil retention is improved.
Further, the portion closer to the lower surface than the predetermined length with little wear on the outer peripheral surface is made a smooth finished surface such as an etching finish, so that the oil retainability can be sufficiently maintained as usual.

  Further, according to this invention, the flexibility of the rough finished surface at a certain length from the upper surface side is greater than the smooth finished surface at the portion closer to the lower surface than the certain length, so that the high-pressure combustion gas is removed from the piston ring. Due to the flexibility of the finished surface at a certain length from the upper surface side when acting on the outer peripheral surface of the sliding surface from the upper surface side, the piston ring is easily deformed and the familiarity is improved, and the piston ring and the cylinder liner The contact pressure with is reduced.

In the present invention, a plurality of dimples by shot peening are engraved on the outer peripheral surface along the outer peripheral surface, and the dimples have a small axial pitch of the piston within a predetermined length from the upper surface side. Are formed in a large number of dimples, and the portion closer to the lower surface than the predetermined length is formed in a small number of dimples having a pitch larger than the small pitch and a small number of dimples (Claim 7), so high-pressure combustion When gas acts on the outer peripheral surface of the sliding surface from the upper surface side of the piston ring, the load on the outer peripheral surface decreases in the axial direction of the piston as the upper surface side becomes larger and the lower surface side.
Therefore, according to this invention, a plurality of dimples by shot peening are engraved along the outer peripheral surface, and the plurality of dimples have a large number of dimples with a small axial pitch of the piston at a certain length from the upper surface side. A portion closer to the lower surface than the predetermined length is formed in a small number of dimples having a pitch larger than the small pitch and a small number of dimples.
Therefore, according to this invention, when wear of the outer peripheral surface of the piston ring progresses, a large number of dimples having a small axial pitch and a large number of dimples are formed at a certain length from the upper surface side. As a result, wear of the dimples is reduced and oil retention is improved.
Further, the portion closer to the lower surface than the predetermined length with less wear of the dimple is formed with a small number of dimples having a larger pitch than the small pitch and a smaller number of dimples, so that the oil retainability can be sufficiently maintained as usual.

  Further, according to the invention, since the dimple is formed in a large number of dimples having a small axial pitch and a large number of dimples at a certain length from the upper surface side, the dimple flexibility is a portion closer to the lower surface than the certain length, that is, The dimple pitch is larger than the part formed on a small number of dimples with a small number of dimples, and when the high-pressure combustion gas acts on the outer peripheral surface of the sliding surface from the upper surface side of the piston ring, it is a certain length from the upper surface side. Due to the flexibility of the dimples, the piston ring can be easily deformed to improve conformability, and the contact pressure between the piston ring and the cylinder liner is reduced.

  As described above, the shape of the plurality of grooves provided along the axial direction of the piston is improved, and the oil retaining property of the sliding outer peripheral surface of the piston ring is maintained while maintaining a predetermined familiar shape. It is possible to prevent the occurrence of seizure of the piston ring and abnormal wear of the sliding outer peripheral surface.

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

6A is a schematic cross-sectional view around a piston of a large diesel engine to which the present invention is applied (showing one side cross-section of the piston), FIG. 6B is an enlarged view of a Z portion in FIG. It is a perspective view which shows the state of the joint.
In FIG. 6 (A), the piston 2 is configured by connecting an inner peripheral piston central portion 2a and an outer peripheral cylindrical portion 2b.
A plurality of piston rings 1 are respectively inserted into ring grooves 3 formed in a plurality of stages in the height direction of the outer peripheral cylindrical portion 2 b, and the piston 2 has an outer peripheral surface 1 c of the cylinder liner 6. It reciprocates while sliding on the sliding surface 6a. A ring side surface gap 7 that opens to the combustion chamber 4 of the engine is formed on the side of the outer peripheral cylindrical portion 2b of the piston 2, and the ring side surface gap 7 is filled with combustion gas from the combustion chamber 4. ing.
As shown in FIG. 6B, the piston ring 1 includes the outer peripheral surface 1c, an upper surface 1a perpendicular to the direction of the axis 100 of the piston 2 that contacts the gas in the combustion chamber 4, and the opposite side of the upper surface 1a. The lower surface 1b formed in this and the inner ring back surface 1d are connected.

When the piston 2 of the engine rises, as shown in FIG. 6B, the piston ring 1 is formed with an upper gap 3a and a back gap 3b, and the upper gap 3a and the back gap 3b have the ring side surface gap. Combustion gas from the combustion chamber 4 side from 7 flows in as shown by arrows.
Further, as shown in FIG. 6 (C), the piston ring 1 is notched at the mating portion, and is connected in a ring shape via the notched mating portion 1e.
As described above, the piston ring 1 is exposed to different gas pressures on the upper surface 1a and the lower surface 1b of the ring, and the high-pressure combustion gas is in contact with the abutment portion 1e and the sliding surface and the upper clearance 3a. And it leaks to the low voltage | pressure side which the lower surface 1b faces through the back clearance 3b. The main leak is a leak from the abutment portion 1e.

  The present invention relates to an improvement in the shape of the piston ring 1.

(First embodiment)
FIG. 1 is an enlarged perspective sectional view of a piston ring of a large diesel engine according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a portion Z in FIG.
In FIG. 6, the piston ring 1 is inserted into the ring groove 3 and touches the gas on the combustion chamber 4 side, and the upper surface 1a perpendicular to the axial direction 100 of the piston 2 and the lower surface formed on the opposite side of the upper surface 1a. 1b, an outer peripheral surface 1c that is coupled to the upper surface 1a and the lower surface 1b and is formed in the axial direction of the piston and slidably contacts the sliding surface 6a of the cylinder liner 6, and a back surface 1d on the back side of the outer peripheral surface 1c. Yes.
When the piston 2 of the engine rises, as shown in FIG. 6, the piston ring 1 is formed with an upper gap 3 a and a back gap 3 b, and the upper gap 3 a and the back gap 3 b are separated from the ring side face gap 7. Combustion gas from the combustion chamber 4 side flows in as shown by an arrow, and presses the outer peripheral surface 1 c against the sliding surface 6 a of the cylinder liner 6.

In the first embodiment, a plurality of grooves 10 (10a, 10b) are formed in the outer peripheral surface 1c along the axial direction 100 of the piston of the outer peripheral surface 1c.
Further, in the first embodiment, above the fixed length S from the upper surface 1a side, the plurality of grooves 10 have a width w, a depth t, and a radius r at the back, as shown in FIG. A groove 10a (FIG. 1) having a width w ₁ , a depth t ₁ , and a radius r _{1 at the} back part is formed. When the fixed length S is reached by approaching the lower surface 1b, the width w ₂ , the depth t ₂ , and the back part are formed. configured radius _{r 2} comprised groove 10b (FIG. 1) of the.
The distance v between the grooves 10a is the smallest in the groove 10a on the upper surface 1a side, and continuously increases from the distance v to the lower groove 10b.

When high-pressure combustion gas acts on the outer peripheral surface 1c of the sliding surface from the upper surface side 1a of the piston ring 1, the load on the outer peripheral surface 1c is larger on the upper surface 1a side in the axial direction 100 of the piston 2 and on the lower surface 1b side. It becomes small as it becomes.
Therefore, according to this embodiment is formed into a number of large groove 10a sized to large That depth t ₁ is deeper and inter-groove distance v of the groove 10 is small in a predetermined length S from the upper surface 1a side, said predetermined length lower surface 1b side of the part than S is formed in the shallow small that depth t ₂ than the size of the large groove 10a and inter-groove distance v is large small groove 10b of the groove 10 Thus, when the wear of the groove 10 progresses, the large number of large grooves 10a are formed at a certain length S from the upper surface 1a side, so that the wear of the groove 10 is less than that of the conventional one, and the oil retaining property is reduced. Will improve.
The smaller the predetermined length lower surface 1b side of the part than S of the wear of the groove 10, reduced i.e. the depth t ₂ the size of the grooves 10b has a shallow and inter-groove distance v is large small groove 10b Therefore, the oil retention can be sufficiently maintained as usual.

Further, since the groove 10 is formed in a large number of large grooves 10a with a certain length S from the upper surface 1a side and the distance v between the grooves is small, it is closer to the lower surface 1b than the certain length S. The portion is a small groove 10b in which the size of the groove 10 is small and the distance v between the grooves is large.
The flexibility of the groove 10a at a certain length S from the upper surface 1a side is larger than the portion closer to the lower surface 1b than the certain length S, so that high-pressure combustion gas flows from the upper surface 1a side of the piston ring 1 to the sliding surface. When acting on the outer peripheral surface 1 c, the flexibility of the groove 10 a at a certain length S from the upper surface 1 a side facilitates deformation of the piston ring 1 and improves conformability, and contact between the piston ring 1 and the cylinder liner 6. The pressure drops.

In the first embodiment, the plurality of grooves 10 are set such that the size of the grooves 10 is a depth t, a width w, and a radius r at the back as shown in FIG. Is increased to form a large groove 10a (depth t ₁ , width w ₁ , back radius r ₁ ) and continuously or intermittently reduced from the large groove 10a at a constant rate. It can be reduced to 1b groove 10b (depth t ₂ , width w ₂ , back radius r ₂ ), and further in groove 10b (depth t ₂ , width w ₂ , back radius r ₂ ). It may be reduced continuously or intermittently at a constant rate.

Thus, when the high-pressure combustion gas acts on the outer peripheral surface 1c of the sliding surface from the upper surface 1a side of the piston ring 1, the load on the outer peripheral surface 1c is on the upper surface 1a side in the direction of the axis 100 of the piston 2. It becomes smaller as it becomes larger on the lower surface 1b side.
However, as in this embodiment, the shape of the groove 10 is reduced continuously or intermittently in the axial direction of the piston 2 from the upper surface 1a side from the large groove 10a having a large size of the plurality of grooves 10. By connecting to the small groove 10b smaller than the large groove 10a, the shape of the groove 10 is changed to the piston 10 as the load on the piston ring 1 becomes smaller as the upper surface 1a side becomes larger and the lower surface 1b side becomes smaller. It will slide and change according to the change of the ring 1 load, and the groove 10 having an appropriate shape according to the load of the piston ring 1 can be provided.

(Second embodiment)
FIG. 3 is an enlarged perspective sectional view of a piston ring of a large diesel engine according to a second embodiment of the present invention.
In the second embodiment, the plurality of grooves 10 provided on the outer peripheral surface 1c have the same shape, and the plurality of grooves 10 having the same shape are in the axial direction of the piston at a certain length S from the upper surface 1a side. Formed in a large number of grooves 10 having a small pitch n and a large number of grooves, and a portion closer to the lower surface 1b than the predetermined length S is formed in a small number of grooves 10 having a larger pitch n and a smaller number of grooves than the small pitch. doing.

That is, in such an embodiment, the the upper surface 1a predetermined length from the side S, in the upper groove 10 of the plurality of identical shape, as shown in FIG. 3, the pitch n n _1, n _2, n _{As shown in 3} , it decreases continuously or intermittently. Below the fixed length S, the pitch n ₄ may be larger than the maximum pitch n ₃ .

According to the second embodiment, the plurality of grooves 10 having the same shape on the outer peripheral surface 1c have a plurality of grooves 10 having a small piston biaxial pitch n and a large number of grooves at a constant length S from the upper surface 1a side. Since the portion closer to the lower surface 1b than the predetermined length S is formed in a small number of grooves 10 having a pitch n larger than the small pitch and a smaller number of grooves, the plurality of grooves 10 have the same size. Even so, when the pitch n of the grooves 10 is a certain length S from the upper surface 1a side, a large number of grooves 10 having a small number of grooves such as pitches n ₁ , n ₂ , and n ₃ are provided, portions of the lower surface 1b toward has a small number of grooves 10 the number of large groove is small as the pitch n ₄ than the S.
As a result, when the wear of the groove 10 progresses, the groove 10 is formed in a large number of grooves 10 by reducing the pitch n of the groove at a certain length S from the upper surface 1a side. Thus, the oil retention is improved, and the portion closer to the lower surface 1b than the predetermined length S where the wear of the groove 10 is small is increased to a small number of grooves 10 with a larger pitch n and a larger distance between the grooves. As a result, the oil retainability can be sufficiently maintained as usual.

In addition, as described above, in the fixed length S from the upper surface 1a side, the plurality of grooves 10 having the same shape have the piston axial pitch n as n ₁ , n ₂ , n ₃ as described above. Formed in a large number of grooves 10 with a small number of grooves, and a portion closer to the lower surface 1b than a certain length S is formed in a small number of grooves 10 with a large pitch n and a small number of grooves.
The flexibility of the large number of grooves 10 at a certain length S from the upper surface 1a side becomes larger than the small number of grooves 10 nearer to the lower surface 1b than the certain length S, so that high-pressure combustion gas is transferred to the upper surface of the piston ring 1. Deformation of the piston ring 1 due to the flexibility of a large number of grooves 10 of small pitches n ₁ , n ₂ , n _{3 at} a fixed length S from the upper surface 1a side when acting on the outer peripheral surface 1c of the sliding surface from the 1a side Becomes easier, the familiarity is improved, and the contact pressure between the piston ring 1 and the cylinder liner 6 is lowered.

In the second embodiment, the plurality of grooves 10 having the same shape have a number of grooves 10 and the axial pitch n of the piston 2 from the upper surface 1a is set to n ₁ , n ₂ , n ₃ , n _4. as in, by continuously decreases at a constant rate, it is also possible to configure the groove 10 in the lower surface 1b to be coupled to the few number of grooves n _4.

Here, when high-pressure combustion gas acts on the outer peripheral surface 1c of the sliding surface from the upper surface 1a side of the piston ring 1, the load on the outer peripheral surface 1c is large on the upper surface 1a side in the axial direction of the piston 2, and the lower surface 1b. It gets smaller as it gets closer.
In such an embodiment, even if the shape of the plurality of grooves 10 is the same, the plurality of grooves 10 has a large number of grooves 10 and the axial pitches n ₁ , n ₂ , n ₃ , The number of grooves is continuously decreased at a constant rate, such as n ₄ , and connected to the small number of grooves 10.
Accordingly, as the piston ring load becomes larger as the upper surface 1a side becomes larger and becomes the lower surface 1b side, the axial pitch n of the groove 10 also becomes the piston ring load of n ₁ , n ₂ , n ₃ , n ₄ . The groove 10 having a proper shape according to the change of the piston ring load can be provided by sliding to the change.
In the second embodiment, the configuration other than the above is the same as that of the first embodiment, and the same members are denoted by the same reference numerals.

(Third embodiment)
FIG. 4A is an enlarged perspective sectional view of a piston ring of a large diesel engine according to a third embodiment of the present invention, and FIG. 4B is an enlarged view of a Y part of FIG.
In the third embodiment, the outer circumferential surface 1c, a rough finish surface 11a in a predetermined length B ₁ from the upper surface 1a side in the axial 100 direction of the piston along the outer circumferential surface 1c, than the predetermined length B ₁ also part B ₂ of the lower surface 1b toward constitutes a smooth finished surface 11b than the rough finish surface 11a.
Preferably, the rough finish surface 11a is a ground finish surface by a grinder, and the smooth finish surface 11b is formed by etching finish.

  Here, when high-pressure combustion gas acts on the outer peripheral surface 1c of the sliding surface from the upper surface 1a side of the piston ring 1, the load on the outer peripheral surface 1c is large on the upper surface 1a side in the axial direction of the piston 2, and on the lower surface 1b side. It becomes small as it becomes.

Therefore, according to the third embodiment, a rough finish surface 11a of the grinding finish due grinder in a predetermined length B ₁ from the upper surface 1a side, part B ₂ of the lower surface 1b nearer the predetermined length B ₁ represents etching with the arrangements in rough finish surface smooth finished surface 11b than 11a of finishing, etc., at the time of wear progress of the piston ring 1, rough finished surface of finish grinding, etc. by the grinder in a predetermined length B ₁ from the upper surface 1a side By forming in 11a, the wear of the outer peripheral surface 1c is less than that of the conventional one, and the oil retention is improved.
The portion B ₂ of the lower surface 1b nearer less the predetermined length of the wear of the outer circumferential surface 1c, by which a smooth finished surface 11b such as etching finishing can safely hold retention of normal oil.

Further, the flexibility of the rough finish surface 11a in a predetermined length B ₁ from the upper surface 1a side, the larger than smooth finished surface 11b of the portion of the lower surface 1b nearer predetermined length B _1, high-pressure combustion gas from the upper surface 1a side of the piston ring 1 when acting on the outer circumferential surface 1c of the sliding surface, the flexibility of the finished surface in a predetermined length B ₂ from the upper surface 1a side, conformability to the deformation of the piston ring 1 is easier And the contact pressure between the piston ring 1 and the cylinder liner 6 decreases.
In the third embodiment, the configuration other than the above is the same as that of the first embodiment, and the same members are denoted by the same reference numerals.

(Fourth embodiment)
FIG. 5A is an enlarged perspective view of a piston ring of a large diesel engine according to a fourth embodiment of the present invention, and FIG. 5B is an AA arrow view of FIG.
In the fourth embodiment, a plurality of dimples 12 (12a, 12b) by shot peening are engraved on the outer peripheral surface 1c of the piston ring 1 along the outer peripheral surface 1c. forming a large number of dimples 12a number of pitches in the axial direction is small dimples is large piston in a predetermined length C ₁ from the 1a side, the predetermined length portion C ₂ of the lower surface nearer C ₁ than the small pitch However, a small number of dimples 12b having a large pitch and a small number of dimples are formed.

Here, when high-pressure combustion gas acts on the outer peripheral surface 1c of the sliding surface from the upper surface 1a side of the piston ring 1, the load on the outer peripheral surface 1c is large on the upper surface 1a side in the axial direction of the piston 2, and on the lower surface 1b side. It becomes small as it becomes.
However, in the fourth embodiment, engraved a plurality of dimples 12 by shot peening along the outer circumferential surface 1c, dimples 12 wherein the plurality of axial pistons 2 in a predetermined length C ₁ from the upper surface 1a side forming a large number of dimples 12a a large number of directions pitch is small dimples 12, portions of the predetermined length C ₁ undersurface nearer to the small number of dimples 12b fewer pitches larger dimples 12 than the small pitch Forming.
Therefore, when wear advances in the outer peripheral surface 1c of the piston ring 1, wherein in the upper surface 1a a predetermined length from the side C _1, by axial pitch was formed on a large number of dimples 12a large number of small dimples, conventional The dimple 12a is less worn than the dimple 12a, and the oil retention is improved.
Further, the portion C ₁ closer to the lower surface than the predetermined length with less wear of the dimple 12 is formed in a small number of dimples 12b having a pitch larger than the small pitch and a small number of the dimples 12, so that the oil retainability is maintained as usual. It can be retained sufficiently.

Further, according to the fourth embodiment, since in certain length C ₁ from the upper surface 1a side is formed in a large number of dimples 12a large number of axial pitch is small dimples 12a, flexibility of dimples 12a are the predetermined length greater than the portion C ₂ is also formed a small number of dimples 12b fewer of the lower surface side of the portion C _2, that dimple pitch is larger dimples 12b than, high pressure combustion gas from the upper surface 1a side of the piston ring 1 when acting on the outer peripheral surface 1c of the sliding surface, the flexibility of the dimple 12a in a predetermined length C ₁ from the upper surface 1a side, improved conformability making it easy deformation of the piston ring 1, the piston ring 1 The contact pressure with the cylinder liner 6 decreases.
In the fourth embodiment, the configuration other than the above is the same as that of the first embodiment, and the same members are denoted by the same reference numerals.

  According to the present invention, the shape of the outer peripheral surface of the piston ring is improved with an extremely simple structure, and the piston ring is made to quickly reach a predetermined familiar shape while keeping the oil retaining property of the sliding outer peripheral surface of the piston ring. It is possible to provide a piston ring for a reciprocating engine that prevents the occurrence of seizure and abnormal wear of the outer peripheral surface of the slide.

It is an expansion perspective sectional view of the piston ring of the large-sized diesel engine concerning the 1st example of the present invention. It is the Z section expanded sectional view of FIG. It is an expansion perspective sectional view of the piston ring of the large-sized diesel engine concerning the 2nd example of the present invention. (A) is an expanded perspective sectional view of a piston ring of a large diesel engine according to a third embodiment of the present invention, and (B) is an enlarged view of the Y part of (A). (A) is an expansion perspective view of the piston ring of the large sized diesel engine which concerns on 4th Example of this invention, (B) is an AA arrow line view of (A). (A) is a schematic sectional view around a piston of a large-sized diesel engine to which the present invention is applied (showing one side sectional view of the piston), (B) is an enlarged view of a Z portion in (A), and (C) is a fitting of a piston ring. It is a perspective view which shows the state of an opening | mouth. It is an expansion perspective view of the piston ring of the large sized diesel engine which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston ring 1a Upper surface 1b Lower surface 1c Outer peripheral surface 1d Rear surface 2 Piston 3 Ring groove 6 Cylinder liner 6a Sliding surface 10 Groove 10a Groove 10b Groove 11a Rough finish surface 11b Smooth finish surface 12a, 12b Dimple

Claims (7)

A cylinder liner that is coupled to an upper surface that is in contact with gas on the combustion chamber side perpendicular to the axial direction of the piston, a lower surface that is formed on the opposite side of the upper surface, and the upper and lower surfaces, and is formed in parallel to the axial direction of the piston. In a piston ring of a reciprocating engine having an outer peripheral surface that is in sliding contact with the sliding surface of
A plurality of grooves are engraved on the outer peripheral surface along the axial direction of the piston on the outer peripheral surface, and the plurality of grooves have a depth that is deeper between the grooves at a predetermined length from the upper surface side. The reciprocation is characterized in that it is formed in a large number of large grooves with a small distance, and the portion closer to the lower surface than the fixed length is formed into a small groove whose depth is shallower than the large grooves and the distance between the grooves is large. Piston ring of a dynamic engine. The plurality of grooves are formed by continuously reducing the depth of the grooves and reducing the distance between the grooves from the large groove having a deep groove depth in the axial direction of the piston from the upper surface side. 2. The piston ring of a reciprocating engine according to claim 1, wherein the piston ring is connected to the small groove smaller than the reciprocating engine. A cylinder liner that is coupled to an upper surface that is in contact with gas on the combustion chamber side perpendicular to the axial direction of the piston, a lower surface that is formed on the opposite side of the upper surface, and the upper and lower surfaces, and is formed in parallel to the axial direction of the piston. In a piston ring of a reciprocating engine having an outer peripheral surface that is in sliding contact with the sliding surface of
A plurality of grooves having the same shape are formed in the outer peripheral surface along the axial direction of the piston on the outer peripheral surface, and the plurality of grooves are grooves with a small axial pitch of the piston within a predetermined length from the upper surface side. A piston for a reciprocating engine characterized in that it is formed in a large number of grooves having a large number of grooves, and a portion closer to the lower surface than the predetermined length is formed in a small number of grooves having a larger pitch than the small pitch and a smaller number of grooves. ring.   The plurality of grooves having the same shape are connected to the small number of grooves by reducing the number of grooves by continuously decreasing the axial pitch of the piston from the upper surface side from the large number of grooves. 4. A piston ring for a reciprocating engine according to claim 3, wherein: The upper surface of the combustion chamber side perpendicular to the axial direction of the piston is in contact with the gas, the lower surface formed on the opposite side of the upper surface, and the upper surface and the lower surface. In a piston ring of a reciprocating engine having an outer peripheral surface in sliding contact with the moving surface,
The outer peripheral surface has a rough finish surface at a certain length in the axial direction of the piston from the upper surface side along the outer peripheral surface, and the portion closer to the lower surface than the predetermined length is smoother than the rough finish surface. A piston ring for a reciprocating engine characterized by comprising a surface.   6. The piston ring of a reciprocating engine according to claim 5, wherein the rough finish surface is ground by a grinder and the smooth finish surface is etched. The upper surface of the combustion chamber side perpendicular to the axial direction of the piston is in contact with the gas, the lower surface formed on the opposite side of the upper surface, and the upper surface and the lower surface. In a piston ring of a reciprocating engine having an outer peripheral surface in sliding contact with the moving surface,
A plurality of dimples by shot peening are engraved on the outer peripheral surface along the axial direction of the piston on the outer peripheral surface, and the plurality of dimples are dimples with a small axial pitch of the piston within a certain length from the upper surface side. A piston for a reciprocating engine characterized in that it is formed in a large number of dimples having a large number of and a portion closer to the lower surface than the predetermined length is formed in a small number of dimples having a pitch larger than the small pitch and a small number of dimples. ring.

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