JP2008008420A - Oil ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil ring superior in oil consumption and easy to manufacture, having reduced friction by permitting the uniform slide contact of the outer peripheral faces of two rails with the inner wall face of a cylinder at all times. <P>SOLUTION: The oil ring comprises two body rail parts, an oil ring body 10 whose cross section is approximately L-shaped, connected with a columnar part joining the two body rail parts to each other, and an expander 20 for energizing the oil ring radially outward. On the outer peripheral face side of the oil ring body between the two body rail parts, an annular groove 14 is formed whose axial cross section is circular. A slidable and rockable rocking ring is arranged in the annular groove. The axial cross section shape of the inner peripheral face of the rocking ring corresponds to the shape of the annular groove, and the rocking ring is movable in the circular direction. On the outer peripheral face side of the rocking ring, annular first and second rail parts 31, 32 are provided which are separated from each other in the axial direction. The rail parts are protruded radially outward from the two body rail parts 12, 13 of the oil ring body 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an oil ring that is attached to a piston in an internal combustion engine, and in particular, includes a low oil ring body that performs an oil scraping action, and an expander that biases the oil ring body radially outward. The present invention relates to an oil ring that can reduce oil consumption by friction.

  In recent years, in an internal combustion engine, reduction of the frictional force of each sliding part in an internal combustion engine piston or the like has been an important issue for improving fuel efficiency. Particularly in a piston ring that slides on the inner wall surface of the cylinder, the tension tends to be lowered because the reduction of the tension is effective for reducing the frictional force of the pressure ring and the oil ring. However, as the tension is reduced (the value obtained by dividing the total tension of two pressure rings and one oil ring by the cylinder inner diameter is 0.20 N / mm to 0.25 N / mm), the sealing function of the oil ring is impaired. There was a problem that the oil consumption increased and the oil consumption increased.

  The main functions of the oil ring are the oil scraping function and the oil control function that controls the oil consumption. In order to improve these functions, the oil ring axial width is reduced. Has been developed. Referring to an example of a conventional oil ring with a reduced width, as shown in FIG. 5, the oil ring 1 has a substantially I-shaped cross section in which two rails 12B and 13B are connected by a pillar portion. . In this example, two rails 12B and 13B are formed symmetrically. The outer peripheral annular groove 14B formed by connecting the rails 12B and 13B with the pillar portion 18B is a groove for receiving oil scraped from the cylinder inner wall surface by the sliding surface, and further, the outer peripheral annular groove 14B. The oil received in the oil passes through the through holes 15B provided in a large number in the column portion 18B, and moves to the inner peripheral side of the oil ring 1.

  In the oil ring having such a configuration, from the viewpoint of reducing oil consumption, the oil ring oil control function is achieved by reducing the width in the axial direction of the oil ring, that is, the axial height (h1) shown in FIG. Is increasing. The smaller the h1 dimension, the lower the friction, so it is advantageous for reducing oil consumption. However, the structure that always tries to make a flat contact with the cylinder inner wall keeps the contact surface formed in the initial stage for a long time. Will be.

  Since the wedge effect does not contribute to the flat surface, the oil film on the sliding surface is thin, and the frictional force increases when the thin oil film is sheared on the flat and wide surface. Even an oil ring is operated with fluid lubrication in most areas of the process, so in the case of a thin oil film, the velocity gradient in the oil film increases, and the shear force increases as the velocity gradient increases. In the region where high shear force is generated, the friction increases over the entire surface.

  In order to avoid this, it is most important to reduce the width per sliding surface. However, if the contact surface pressure with the cylinder inner wall surface increases by reducing the width per sliding surface, the oil scraping function and the oil control function are improved, but wear increases, so the surface pressure is easily increased. It cannot be set.

In the conventional oil ring described in Patent Document 1, a pair of annular rail grooves are formed along the outer peripheral side surface of the oil ring body, and the pair of annular rail grooves are thin plates so as to pass through the joint portion of the oil ring body. An annular rail is mounted. The outer peripheral edge of the annular rail protrudes radially outward from the outer peripheral surface of the oil ring body, and slides against the cylinder inner wall surface. According to such a configuration, only the annular rail that forms the sliding portion may be formed of a material having good wear resistance, and the oil ring body can be manufactured with a low-cost material, and the oil ring body is subjected to a surface treatment. There is no need. Furthermore, leakage of oil from the joint portion of the oil ring body can be prevented by a pair of annular rails.
Japanese Patent Laid-Open No. 3-88946

  However, in the oil ring according to Patent Document 1, it is necessary to perform the annular rail groove processing on the outer peripheral surface of the oil ring main body in order to mount the annular rail. Further, it is considered that the annular rail sliding with the cylinder inner wall surface is twisted by the vertical movement of the piston, and the thin annular rail itself cannot withstand the twist and may be broken.

  Furthermore, the outer circumference of a pair of annular rails when the piston reciprocates with the piston axis slightly tilted with respect to the cylinder inner wall axis due to incomplete piston rounding or assembly errors. The surface does not necessarily contact the inner wall of the cylinder evenly. If a small gap occurs when a part of the outer peripheral surface of one annular rail is separated from the inner wall of the cylinder, oil leaks from this gap and adversely affects oil consumption. May come.

  Therefore, the present invention slides with the inner wall surface of the cylinder due to the vertical movement of the piston, and there is no problem of breakage even if a twist occurs, and the outer peripheral surfaces of the two rails can be slidably contacted with the inner wall surface of the cylinder at all times. It is another object of the present invention to provide an oil ring that reduces sliding friction and is excellent in oil consumption and easy to manufacture.

  In order to achieve such an object, the present invention provides two main body rail portions, an oil ring main body having a substantially I-shaped cross section connected by a column portion connecting the two main body rail portions, and an inner peripheral surface of the oil ring main body. An oil ring for an internal combustion engine having an expander that is positioned on the side and urges the oil ring outward in the radial direction, the outer ring surface side of the oil ring body, and the two body rail portions. An annular groove having an arc-shaped cross section in the axial direction is formed between them, and a swing ring that can slide and swing is disposed in the annular groove, and the axial cross section of the inner peripheral surface of the swing ring The shape matches the shape of the annular groove, and the oscillating ring can move in an arc direction with respect to the annular groove, and a sliding surface for the inner wall surface of the cylinder is formed on the outer peripheral surface side of the oscillating ring. An annular first rail portion and second rail portion that are separated from each other in the axial direction are provided. Is, first rail portion and the second rail part is providing oil ring projecting radially outward of the two main rail portion of the oil ring body.

  Here, the oil ring body is formed with one abutment, the swing ring is formed with a single abutment, and the abutment of the oil ring body and the abutment of the swing ring Are displaced from each other in direction.

  According to the oil ring of the first aspect, since the swing ring is swingable with respect to the oil ring main body, the entire outer peripheral surfaces of the first rail portion and the second rail portion are always kept during reciprocation of the piston. It can be slidably contacted with the inner wall surface of the cylinder. Accordingly, oil leakage can be prevented and an increase in oil consumption can be suppressed. Even if the piston is inclined with respect to the inner wall surface of the cylinder and the oil ring is inclined, the entire outer peripheral surfaces of the first rail portion and the second rail portion follow the inner wall surface of the cylinder well by the swing of the swing ring. be able to.

  Further, since the first rail portion and the second rail portion are a part of the swing ring and are integrated with each other, the first rail portion and the second rail portion are excellent in rigidity as compared with the plate-shaped rail, and there is no fear of breakage.

  Furthermore, if the contact width of the outer peripheral surface (sliding surface) of the first rail portion and the second rail portion of the swing ring with respect to the inner wall surface of the cylinder is made small, an oil ring having a high surface pressure can be provided.

  Further, only the first rail portion sliding surface and the second rail portion sliding surface having a small contact width with respect to the cylinder inner wall surface of the swing ring slide relative to the cylinder inner wall surface. When wear of the first rail portion sliding surface and the second rail portion sliding surface of the swing ring has progressed, these sliding surfaces are separated from the two body rail portion sliding surfaces of the oil ring body. The first rail portion sliding surface and the second rail portion sliding surface are flush with the cylinder inner wall surface, and the sliding surface of the main body rail portion also slides with respect to the cylinder inner wall surface. At this time, with respect to the cylinder inner wall surface, the progress of wear can be prevented by the sliding of the main body rail portion and the first rail portion and the second rail portion of the swing ring.

  According to the oil ring of the second aspect, since the joint portion of the oil ring main body and the joint portion of the swing ring are arranged to be shifted from each other in the ring circumferential direction, oil leakage from the joint portion of the oil ring main body Can be prevented by the rocking ring. Therefore, even if the wear of the sliding surface of the first rail portion and the sliding surface of the second rail portion progresses and the surface pressure decreases, oil leakage from the joint portion can be prevented, so that the oil consumption is reduced as a whole. be able to.

  Hereinafter, an oil ring according to a first embodiment of the present invention will be described with reference to FIGS. The oil ring 1 includes an oil ring main body 10, a coil expander 20, and a swing ring 30. The oil ring main body 10 is made of steel and includes a joint portion 16. An inner circumferential side annular groove 11 having a substantially semicircular cross section in the ring axis direction is formed on the inner circumferential surface side, and the coil expander 20 is combined. Main body rail portions 12 and 13 are provided on the outer peripheral surface side. It is desirable to form a wear-resistant film such as PVD, DLC, nitriding, Cr plating on the sliding surfaces of the main body rail portions 12 and 13. An outer peripheral annular groove 14 having an arcuate cross section in the axial direction is formed between the main body rail portions 12 and 13. A plurality of through holes 15 extending in the radial direction are formed at substantially equal intervals in the circumferential direction of the ring at substantially the center in the axial direction of the oil ring main body 10. The through hole 15 has an oval shape that is longer in the circumferential direction than in the ring axis direction. The oil scraped off through the through hole 15 can be quickly discharged to an oil drain hole on the back side of an oil ring groove (not shown).

  The coil expander 20 is for urging the oil ring main body 10 radially outward to apply tension, and is mounted in the inner circumferential annular groove 11 of the oil ring main body 10. In FIG. 1, hatched circles shown in the coil expander 20 indicate the cross section of the wire constituting the coil expander 20.

  The swing ring 30 is disposed so as to be swingable while sliding in the outer circumferential annular groove 14 of the oil ring body 10. The cross-sectional shape along the ring axis direction of the inner peripheral surface of the swing ring 30 matches the cross-sectional shape of the outer peripheral annular groove 14, and the swing ring 30 has an outer peripheral annular groove with respect to the outer peripheral annular groove 14. It can move in the direction of 14 arcs. An annular first rail portion 31 and a second rail portion 32 are provided on the outer peripheral surface side of the swing ring 30 and form a sliding surface with respect to a cylinder inner wall surface (not shown) and are separated from each other in the ring axial direction. The first rail portion 31 and the second rail portion 32 protrude outward in the radial direction from the main body rail portions 12 and 13 of the oil ring main body 10. It is desirable to form a wear-resistant film such as PVD, DLC, nitriding, Cr plating or the like as a wear-resistant layer on the surface of the first rail portion 31 and the second rail portion 32 that slides with the cylinder inner wall surface.

  The swing ring 30 can obtain a desired cross-sectional shape by drawing or cutting a steel wire. Specifically, it is made from a wire having a diameter of 0.5 to 1.5 mm, and the contact width (L3 in FIG. 3) of the first rail portion 31 and the second rail portion 32 with respect to the cylinder inner wall surface is 0.1 to 0, respectively. About 3 mm. It is preferable to use martensitic stainless steel (SUS440B, SUS440C) as the rocking ring material. In the present embodiment, the outer peripheral surface side of the swing ring 30 between the first rail portion 31 and the second rail portion 32 has a concave shape in the cross section in the ring axis direction. Here, the first rail portion 31 and the second rail portion 32 are formed so that the thickness in the ring axis direction gradually increases from the sliding surface side toward the anti-sliding surface side. If the contact width of the outer peripheral surfaces (sliding surfaces) of the first rail portion 31 and the second rail portion 32 with respect to the inner wall surface of the cylinder is made small, an oil ring with a high surface pressure can be provided. Further, by gradually increasing the thickness, the contact width with respect to the inner wall surface of the cylinder gradually increases due to the progress of wear of the first rail portion 31 and the second rail portion 32, and the surface pressure is reduced to reduce the wear amount. Can be made.

  A plurality of through-holes 33 extending in the radial direction and larger in number than the number of through-holes 15 in the oil ring main body 10 are provided at substantially the center in the axial direction of the swing ring 30 at equal intervals in the circumferential direction of the ring. It is formed to be able to communicate with the through hole 15. The through-hole 33 is preferably a perfect circle, and the inner diameter thereof is smaller than the length of the through-hole 15 of the oil ring body 10 in the ring axial direction and the length in the ring circumferential direction. This is because the oscillating ring 30 oscillates with respect to the oil ring main body 10 so as to ensure the communication with the through hole 15 even in the oscillating state. Since the number of through holes 33 in the swing ring 30 is larger than the number of through holes 15 in the oil ring body 10 and the sizes of the through holes 15 and 33 are different from each other, the through holes 15 and 33 are possible. As long as they can communicate with each other.

  The oscillating ring 30 has a joint portion 34, and the position thereof is different from the joint portion 16 of the oil ring main body 10 in the ring circumferential direction. By mounting the abutment portions 16 and 34 so as to be shifted from each other, it is possible to eliminate an apparent abutment gap, and there is no remaining oil scraping, so that it is possible to maintain wear resistance without increasing oil consumption. it can. Therefore, even if the wear of the first rail portion 31 and the second rail portion 32 progresses and the surface pressure decreases, oil leakage from the joint portion 16 can be prevented, so that the oil consumption can be reduced as a whole. it can.

  As described above, since the swing ring 30 can swing with respect to the oil ring main body 10, the entire outer peripheral surfaces of the first rail portion 31 and the second rail portion 32 are always in the cylinder inner wall surface during the reciprocating motion of the piston. Can be slidably contacted. Accordingly, oil leakage can be prevented and an increase in oil consumption can be suppressed. Further, even if the piston is inclined with respect to the inner wall surface of the cylinder and the oil ring is inclined, the entire outer peripheral surface of the first rail portion 31 and the second rail portion 32 is uniformly distributed due to the swing of the swing ring 30. Can follow. In addition, since the first rail portion 31 and the second rail portion 32 are a part of the swing ring 30 and are integrated with each other, the first rail portion 31 and the second rail portion 32 are superior in rigidity and do not break.

  Further, only the sliding surface of the first rail portion 31 and the sliding surface of the second rail portion 32 having a small contact width with respect to the cylinder inner wall surface of the swing ring 30 slide with respect to the cylinder inner wall surface. When the wear of the first rail portion sliding surface 31 and the second rail portion 32 sliding surface of the swing ring 30 has progressed, these sliding surfaces are the body rail portions 12, 13 of the oil ring body 10. The first rail portion sliding surface 31 and the second rail portion sliding surface are the same surface with respect to the cylinder inner wall surface, and the sliding surfaces of the main body rail portions 12 and 13 having a wide contact width also slide with respect to the cylinder inner wall surface. Move. Accordingly, it can function as a ring having a low surface pressure and prevent progress of wear.

  Next, an oil consumption test of the oil ring (referred to as Example 1) according to the present embodiment will be described with reference to FIGS.

  As shown in FIG. 3, the material of the oil ring body 10 of Example 1 is equivalent to SUS410 material (C: 0.65 mass%, Si: 0.40 mass%, Mn: 0.35 mass%, P: 0.03% by mass or less, S: 0.03% by mass or less, Cr: 13.5% by mass, Mo: 0.3% by mass, balance: Fe), axial length h1 is 1.5 mm, radius The direction width a1 was 1.7 mm. Further, the length L1 of the main body rail portions 12 and 13 in the ring axis direction was 0.2 mm. Furthermore, 34 through-holes 15 having a length in the ring axis direction of 0.5 mm and a length in the ring circumferential direction of 1.5 mm were formed using a punch. The material of the rocking ring 30 is equivalent to SUS440B (C: 0.90 mass%, Si: 0.40 mass%, Mn: 0.35 mass%, P: 0.04 mass% or less, S: 0.04 mass) %: Cr: 17.5% by mass, Mo: 1.15% by mass, V: 0.12% by mass), and was prepared by hot drawing using a die. The length L2 in the ring axis direction of the outer circumferential annular groove of the oil ring main body is 1.1 mm, and the length (per contact width) L3 in the ring axis direction of the outer peripheral surfaces of the first and second rail portions 31 and 32 is 0.1 mm. Met. The through-holes 33 were formed at 40 locations with an inner diameter of 0.3 mm using a drill. When the swing ring 30 is mounted on the oil ring main body 10, the protrusion amount x of the outer peripheral surfaces of the first and second rail portions 31 and 32 of the swing ring from the outer peripheral surface of the main body rail portions 12 and 13 is 5 μm. It was. The distance a12 in the ring radial direction from the outer peripheral surfaces of the first and second rail portions 31 and 32 to the inner peripheral surface of the expander 20 was 2.3 mm.

  As shown in FIG. 4, the oil ring of Comparative Example 1 is an oil ring described in Patent Document 1. The material of the oil ring body, the dimensions h1, a1, a12 and the size and number of the through holes are the same as those in the first embodiment. An annular groove for mounting a pair of annular rails 35 is formed on the outer peripheral surface side of the oil ring main body 10A. The annular rail 35 is made of the same material as that of the swing ring of the first embodiment, and the length of the outer peripheral surface in the ring axis direction (the contact width) is 0.2 mm for a pair of annular rails. The distance x between the outer peripheral surface of the annular rail 35 and the outer peripheral surface of the oil ring main body 10A was 5 μm.

  As shown in FIG. 5, the oil ring of Comparative Example 2 is a conventional oil ring. The material of the oil ring main body 10B, the dimensions h1 and a12, and the size and number of the through holes are the same as in the first embodiment. The dimension a1 'corresponds to the sum of the dimension a1 and x.

  An oil consumption test of the oil rings of Example 1, Comparative Example 1, and Comparative Example 2 was performed using an engine with a displacement of 2000 cc and an in-line 4 cylinder (cylinder inner diameter: 86 mm). At this time, the oil consumption after 3 hours was examined at an engine speed of 4000 rpm by WOT (full load). Each oil consumption index (oil consumption ratio) when the oil consumption (g / h) of Comparative Example 1 is 1.00 is shown in FIG. As is apparent from the graph of FIG. 6, when the oil consumption of Comparative Example 1 is 1.00, the oil consumption of Comparative Example 2 is 1.15, but the oil consumption of Example 1 is 0. It was extremely low at .80, and a good oil consumption reduction effect was observed in this embodiment.

  A modification of the swing ring of the present embodiment is shown in FIGS. The swing ring 30 ′ in FIG. 7 is obtained by dividing a pipe-shaped wire material into approximately two equal parts in a circular cross section, and end surfaces thereof correspond to the outer peripheral surfaces of the first rail portion 31 ′ and the second rail portion 32 ′. 8 has an arc shape whose outer peripheral surface has a larger radius than the inner peripheral surface, and the thickness of the first rail portion 31 ″ and the second rail portion 32 ″ is the anti-cylinder inner wall surface. It gradually increases in the direction.33'33 "is a through hole. In any modification, performance equivalent to that of the rocking ring 30 according to the first embodiment can be exhibited.

  The oil ring of the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention. For example, the expander is not limited to the coil expander as long as it applies tension to the oil ring body, and may be a plate expander.

1 is a schematic sectional view of an oil ring according to an embodiment of the present invention. The fragmentary perspective view which looked at the oil ring by embodiment of this invention from the outer peripheral surface side. The schematic sectional drawing which shows the dimension of the oil ring of Example 1 based on embodiment of this invention. FIG. 3 is a schematic cross-sectional view showing dimensions of an oil ring of Comparative Example 1. FIG. 6 is a schematic cross-sectional view showing dimensions of an oil ring of Comparative Example 2. The graph which shows the oil consumption ratio of the comparative example 2 and Example 1 with respect to the comparative example 1. FIG. The schematic sectional drawing which shows the 1st modification of the rocking | fluctuation ring used for the oil ring of this invention. The schematic sectional drawing which shows the 2nd modification of the rocking | ringing ring used for the oil ring of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oil ring 10 Oil ring main body 11 Inner peripheral side annular groove 12, 13 Main body rail part 14 Outer peripheral side annular groove 15, 33, 33'33 "Through-hole 16, 34 Joint part 18 Column part 20 Coil expander 30 Swing ring 31 1st rail part 32 2nd rail part 35 Annular rail

Claims (2)

An oil ring body having a substantially I-shaped cross section connected by two main body rail parts and a pillar part connecting the two main body rail parts;
In an oil ring for an internal combustion engine comprising an expander positioned on the inner peripheral surface side of the oil ring main body and biasing the oil ring outward in the radial direction,
An annular groove having an arcuate cross section in the axial direction is formed between the two main body rail portions on the outer peripheral surface side of the oil ring main body,
A swing ring that can slide and swing is disposed in the annular groove, and the axial cross-sectional shape of the inner peripheral surface of the swing ring matches the shape of the annular groove, and the swing ring is An annular first rail portion and a second rail portion which are movable in an arc direction with respect to the annular groove, and which form a sliding surface with respect to the inner wall surface of the cylinder on the outer peripheral surface side of the swing ring and are separated from each other in the axial direction The oil ring is characterized in that the first rail portion and the second rail portion protrude radially outward from the two main body rail portions of the oil ring main body.   The oil ring body is formed with a single abutment, the swing ring is formed with a single abutment, and the abutment of the oil ring body and the abutment of the swing ring are mutually circumferential. The oil ring according to claim 1, wherein the oil ring is displaced.

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