JP5425525B2 - piston ring - Google Patents

Description

The present invention relates to a piston ring, and more particularly to a piston ring used for a seal of an internal combustion engine or a compressor.

A piston ring used in an internal combustion engine engine such as an automobile including a truck and a bus and a reciprocating compressor, for example, as shown in FIG. 5, a pair of rail members 2 arranged vertically and the pair of rail members The three-piece type oil ring (piston ring) which is arranged between the two and includes a spacer expander 9 having a tension to press the rail member 2 in the outer peripheral direction, or the outer peripheral side so as to contact the inner wall of the cylinder as shown in FIG. A two-piece oil ring (piston ring) comprising a piston ring body disposed on the inner periphery of the piston ring body and a coil expander 10 disposed on the inner peripheral side of the piston ring body and having a tension to press the piston ring body in the outer circumferential direction. It is used.

Also, a piston ring has been proposed that has improved sealing performance with the cylinder inner wall and the ring groove. For example, in Patent Document 1, a ring-shaped spring is formed on the inner peripheral side of the elastic ring by forming two upper and lower inclined surfaces on the inner peripheral surface of the elastic ring interposed in contact with the upper and lower surfaces of the ring groove of the piston. A member (coil expander) is brought into contact with the two inclined surfaces, and the tension of the spring member is distributed to the pressing force in the outer circumferential direction and the vertical direction of the elastic ring to ensure the sealing performance between the cylinder inner wall and the ring groove. Piston ring. Further, in Patent Document 2, an elastic ring larger than the upper and lower widths of the ring groove is interposed inside the ring groove of the piston, and the upper and lower surfaces of the ring groove and the upper and lower surfaces of the elastic ring are in close contact with each other to ensure a ring side seal function. The ring-shaped spring member disposed on the inner peripheral side of the elastic ring presses the piston ring body disposed on the outer peripheral side of the elastic ring via the elastic ring in the outer peripheral direction, thereby ensuring the sealing performance with the cylinder inner wall. It is a piston ring.

Japanese Patent Laid-Open No. 9-280373 Japanese Patent Laid-Open No. 9-159023

The conventional three-piece type piston ring exhibits a sealing function with the ring groove by contacting the upper and lower surfaces of the ring groove of the piston with the upper and lower rail members 2 of the piston ring. However, if carbon or the like is deposited between the rail member 2 and the spacer expander 9 due to dirt or deterioration of the engine oil, a stick (adherence) occurs in the ring groove of the piston, and the cylinder inner wall and the ring groove The sealing function between them may be significantly impaired. On the other hand, the conventional two-piece type piston ring has good stick resistance because the piston ring body that functions as a seal with the cylinder inner wall is formed as a single unit, but the side seal with the ring groove of the piston is sufficient. Is not secured.

In addition, the piston ring according to Patent Document 1 distributes the tension in the outer circumferential direction of a ring-shaped spring member arranged on the inner circumferential side of the elastic ring to the outer circumferential direction and the pressing force in the vertical direction of the elastic ring. May be insufficient, and the sealing performance with the cylinder inner wall may be insufficient. Furthermore, since the piston ring according to Patent Document 2 uses an elastic ring larger than the vertical width of the ring groove, it can be considered that the cross-sectional area is large and the rigidity is high. Unable to follow, and seal performance between the upper and lower surfaces of the ring groove cannot be sufficiently exhibited. Further, since the rigidity of the elastic ring is too high, there is a problem that the ring cannot sufficiently follow the deformation of the cylinder and the sealing performance with the cylinder wall cannot be sufficiently ensured. Furthermore, since the axial width of the piston ring is larger than the vertical width of the ring groove, there is a problem in assembling property of the piston ring into the ring groove.

An object of the present invention is to provide a piston ring that is excellent in side sealability and stick resistance with respect to the upper and lower surfaces of a ring groove of a piston and excellent in followability to a cylinder inner wall.

The piston ring according to the present invention can generate an appropriate pressure between the ring groove of the piston and the cylinder wall by the elasticity and shape of the ring main body made of resin and the rail member and the tension ring. In this state, the piston ring is brought into contact to ensure sealing performance between the upper and lower surfaces of the ring groove of the piston and the inner wall of the cylinder, and has stick resistance, and also follows the inner wall of the cylinder during the operation of the piston. It is characterized by excellent.

That is, the piston ring of the present invention includes a ring body having a base portion on the outer peripheral side, an upper and lower thin portion extending toward the inner peripheral side of each ring main body on the upper and lower sides of the base portion, and the thin portion A ring formed of a resin or synthetic rubber having a recess on the inner peripheral side between the upper and lower surfaces of the ring main body in the axial section. projecting Te has a convex curved surface portion abutting the upper and lower sides of the upper and lower surfaces and thin width portion of the ring groove, and a sliding member disposed on the outer peripheral side of the ring body, are integrated into the ring body Further, the present invention is characterized in that it is a single or a plurality of rail members and a tension ring that presses the rail member against the inner wall of the cylinder via the ring body in the recess on the inner peripheral side of the ring body.

The thin width portion of the ring main body of the piston ring of the present invention is a position where a line extending in the ring axial direction from the maximum diameter portion of the recess formed on the inner peripheral side of the ring main body intersects with the upper and lower side surfaces of the ring main body, It is between the inner peripheral side edge parts of the upper and lower side surfaces of the ring body. By contacting the thin width portion of the ring body with the upper and lower surfaces of the ring groove of the piston, the elasticity of the thin width portion of the ring body can be remarkably improved when the piston is operated. .

Further, a resin having a lower elastic modulus than the ring body can be used between the ring body and the rail member disposed on the outer peripheral side of the ring body. Thereby, it is possible to further improve the followability of the piston ring to the cylinder wall.

The thin width parts formed on the upper and lower side surfaces of the ring body made of the resin of the piston ring according to the present invention are capable of following the undulation and deformation in the circumferential direction of the ring groove of the piston due to the characteristics of the resin having a lower elastic modulus than the metal. Can further improve the sealing performance, and particularly reduce the oil consumption.

The piston ring of the present invention is a resin or synthetic rubber ring having a low elastic modulus and a shape having a thin width portion on the upper and lower side surfaces, and therefore, between the upper and lower surfaces of the piston ring groove and the upper and lower surfaces of the piston ring. Excellent side seal performance. Therefore, it is possible to reduce oil consumption due to the influence of intake negative pressure during traveling of a vehicle equipped with a diesel engine and a gasoline engine, particularly during deceleration. In addition, since the ring body and the rail member are combined together without a gap, carbon or the like is not deposited and adhered between the members, and high stick resistance can be obtained. Further, convex curved surface portions projecting upward and downward in the axial direction are formed on the upper and lower side surfaces of the ring body, respectively, and the inner peripheral side of the upper and lower side surfaces is formed as a thin width portion that comes into contact with the upper and lower surfaces of the ring groove. By reducing the cross-sectional area of the main body, especially the cross-sectional area of the inner periphery of the ring main body, it is possible to improve the followability of the piston ring against the deformation of the cylinder and improve the sealing performance between the piston ring and the cylinder inner wall. In particular, oil consumption can be reduced.

The piston ring of the present invention is always stable because the resin ring main body, which has a lower elastic modulus than metal, performs side seals between the upper and lower surfaces of the piston ring groove and the upper and lower surfaces of the piston ring. Therefore, the oil consumption can be reduced and the blow-by amount can be reduced.

It is a schematic sectional drawing of the piston ring by 1st Embodiment of this invention. It is a schematic sectional drawing which shows the state which mounted | wore the piston ring groove with the piston ring by 1st Embodiment of this invention. It is a schematic sectional drawing which shows the state which mounted | wore the piston ring groove with the piston ring by 2nd Embodiment of this invention. It is a schematic sectional drawing which shows the state which mounted | wore the piston ring groove of the comparative example 3 with the piston ring. It is a schematic sectional drawing which shows the state which mounted | wore the conventional 3 piece type piston ring (comparative example 1) to the ring groove | channel of the piston. It is a schematic sectional drawing which shows the state which mounted | wore the conventional 2 piece type piston ring (comparative example 2) to the ring groove | channel of the piston. It is the figure which showed ratio of the oil consumption in the evaluation test of the Example and comparative example of this invention.

Hereinafter, preferred embodiments of the present invention will be described.
FIG. 1 is a diagram showing an outline of a cross-sectional shape of a piston ring according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a state where the piston ring according to the first embodiment is mounted in the ring groove 5 of the piston 4.

The piston ring according to the first embodiment of the present invention has a sealing function between the ring main body 1 made of a resin having a sealing function between the upper and lower surfaces of the ring groove of the piston and the cylinder inner wall 7. Two rail members 2 made of a metal material and a tension ring 3 having a rectangular cross section that generates tension from the inner peripheral side via the ring body 1 so that the rail member 2 is properly pressed against the cylinder inner wall 7. Is done.

The ring main body 1 made of resin has a convex curved surface in which the upper and lower side surfaces E protrude in the axial direction between the inner and outer peripheries in the cross section (radial direction), and the tension ring 3 is arranged on the inner peripheral side of the ring main body 1. A concave portion is provided, and thin portions are provided above and below the concave portion. A sealing function between the upper surface 1a of the resin ring body 1 and the upper surface 5a of the ring groove 5 of the piston 4, and a sealing function between the lower surface 1b of the resin ring body 1 and the lower surface 5b of the ring groove 5 of the piston 4. This is ensured by bringing the ring main body 1 into contact with the upper and lower surfaces of the ring groove 5 and the upper and lower side surfaces E of the ring main body 1 in a state where an appropriate pressing force is generated due to the shape of the ring main body 1 and the elasticity of the resin. The upper and lower side surfaces of the resin ring main body 1 are formed by lines extending in the axial direction of the ring from the position A of the inner peripheral portion F of the concave portion on the inner peripheral side of the ring main body 1. Between the ring crossing position B and the ring body side surface inner end C, the upper and lower surfaces of the ring groove 5 can be in contact with each other, and excellent side surface sealing can be ensured.

The upper and lower side surfaces E of the resin ring main body 1 may have a convex curved surface portion between the inner and outer circumferences in the cross section, or may be a composite surface combining a curved surface portion and a flat surface. The convex curved surface portions of the upper and lower side surfaces E may be formed by a curved surface having a single curvature or a complex curved surface having a plurality of continuous curvatures, and a curved surface and a plane can be combined. Moreover, the inner peripheral part F of the recessed part formed in the inner peripheral side of the ring main body 1 is also formed in the composite surface which combined the curved surface and curved surface and curved surface which consisted of the curved surface of a single curvature or several curvature in the cross section. Can do. Furthermore, the resin ring main body 1 may be provided with an oil passage hole penetrating the outer peripheral side and the inner peripheral side. The shape, number and position of the oil passage hole can be arbitrarily set.

Examples of the material of the ring body 1 include synthetic resin, polyethylene, polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK), polyphenylene sulfone (PPS), polybenzimidazole (PBI), and polyamideimide (PAI). A resin can be preferably used. Synthetic rubber can also be used. Furthermore, the ring main body 1 may be composed of a single resin, may be a composite structure obtained by combining a plurality of resins, or may be a reinforced resin containing carbon fiber or the like.

The rail member 2 is integrated by embedding the inner peripheral side of the rail member 2 on the outer peripheral side of the ring body 1 by means such as joint molding or fitting. On the other hand, the tension ring 3 disposed on the inner peripheral side of the ring main body 1 is also integrated on the inner peripheral side of the ring main body 1 by means such as joint molding or fitting. The ring body 1, the rail member 2, and the tension ring 3 may be integrated by combining means such as joint molding and fitting. For example, the resin ring body 1 and the rail member 2 are integrally molded. The resin ring main body 1 and the tension ring 3 may be integrated by fitting. The ring body 1 and the rail member 2 are preferably integrated by means such as casting the rail member 2 by, for example, an injection molding method.

For the rail member 2, it is preferable to use a metal material such as SUS material, SWRH material, SWRS material according to JIS standards, for example. Further, it is more preferable that the sliding surface of the rail member 2 made of the metal material is used after being subjected to various surface treatments such as diamond-like carbon (DLC), ion plating, chrome plating, and nitriding treatment. The rail member 2 may be made of a nonmetallic material such as a resin excellent in wear resistance or heat resistance, for example, PEEK excellent in wear resistance.

The rail member 2 integrated on the outer peripheral side of the ring body 1 is not limited to two, and may be composed of one rail member or two or more rail members, and a plurality of rail members are combined to form an integrated structure. You may comprise. Moreover, the cross-sectional shape of the rail member 2 is not limited to a rectangular shape, and it is possible to improve the coupling strength when the rail member 2 is coupled by integral joining molding or fitting, and to perform the cylinder of the rail member 2 during the secondary operation of the piston. It is also possible to set a cross-sectional shape that can further improve the performance of following the inner wall 7.

Various shapes used for piston rings, such as a barrel face shape, a taper shape, and a scraper shape, can be applied to the shape of the outer peripheral sliding portion of the rail member 2. In particular, the barrel face shape is more preferable because the contact pressure with the inner wall of the cylinder can be set high, and the outer peripheral sealing performance can be further improved. Moreover, in order to improve the coupling | bonding strength at the time of the rail member 2 being joined to the side surface of the rail member 2 by integral joining molding or fitting, or the follow-up performance to the cylinder inner wall 7 of the rail member 2 further. , Through holes, slits and the like can be provided.

The tension ring 3 disposed in the concave portion on the inner peripheral side of the ring main body 1 is not limited to a rectangular cross section, and can be combined with the ring main body 1 by means such as integral joining molding, fitting or assembling. A solid shape, an expander shape, a coil shape, or the like can be used integrally with the ring body 1 or assembled to the ring body 1. It is more preferable to use a solid ring integrally with the ring body 1.

FIG. 3 is a schematic cross-sectional view showing a state in which the piston ring according to the second embodiment is mounted in the ring groove 5 of the piston 4. The first embodiment is different from the first embodiment only in that a resin having a lower elastic modulus than that of the ring body 1 is disposed between the rail body 2 and the rail member 2 that is disposed on the outer peripheral side of the resin ring body 1. . By setting it as 2nd Embodiment, the rail member 2 and the cylinder inner wall 7 are more appropriately pressed on the outer peripheral side of the resin ring main body 1, and the follow-up performance of the rail member 2 to the cylinder inner wall 7 is further improved. Can do.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

As Example 1 of the piston ring according to the present invention, a piston ring having the configuration shown in FIG. 1 was produced. A convex curved surface portion projecting in the axial direction is formed on at least a part of the upper and lower side surfaces, a concave portion is provided on the inner peripheral side, and a cross section that contacts the ring groove 5 on the upper and lower portions of the concave portion is a thin arc-shaped width A ring body 1 made of a resin having a portion formed thereon, and two rail members 2 integrated with the ring body 1 on the outer peripheral side of the ring body 1. A piston ring was produced by integrating one rectangular cross-section tension ring 3 having an axial width smaller than the width. The resin ring body 1 is made of synthetic resin polybenzimidazole (PBI), the tension ring 3 is made of MC63 (JISB-8032 standard) equivalent material, the two rail members 2 are made of MC68 ( A JIS B-8032 standard material) equivalent material was used, and a piston ring having a nominal diameter of 71.0 mm was produced by an integral molding method using cast-in with a resin injection molding machine. In Example 1, the radius of the curved surface portion formed on the upper and lower side surfaces was 15 mm, and the curved surface formed on the upper and lower surface was constituted by a single curved surface. The concave portion formed in the inner peripheral portion was set to ½ of the radial dimension of the ring body 1. The axial dimension of the piston ring was 2.5 mm, the radial dimension was 3.0 mm, the tension was 5 N, the axial dimension of the rail member 2 was 0.35 mm, and the radial dimension was 1.5 mm. And the outer peripheral sliding part of the two rail members 2 which contact | connects the cylinder inner wall 7 used what coat | covered the ion plating film | membrane excellent in abrasion resistance.

The shape of the joint portion of the piston ring of Example 1 was a straight shape. The shape of the mating portion is not limited to a straight shape, but may be a shape generally applied to a piston ring or a seal ring, such as an oblique mating port or a stepped mating port. In Example 1, the joint gap was set to 0.3 mm.

As Example 2 of the piston ring according to the present invention, a piston ring having the configuration shown in FIG. 3 was produced. The ring body 1, the tension ring 3, and the rail member 2 were made of the same material as in Example 1, and a piston ring having the same nominal diameter and the same shape of each part was produced by an integral molding method using a caster in a resin injection molding machine. In Example 1, polyamideimide (PAI) is disposed as a resin material 8 having a lower elastic modulus than polybenzimidazole (PBI) between the resin ring main body 1 and the two rail members 2. Is different. The structure of the piston ring of the second embodiment further improves the follow-up performance of the two rails in contact with the cylinder inner wall 7 to the cylinder inner wall 7, and has a better sealing performance than the first embodiment.

In order to confirm the effect of the sealing performance and followability of the piston ring according to the present invention, a conventional piston ring was manufactured as a comparative example. As Comparative Example 1 and Comparative Example 2, a three-piece piston ring and a two-piece piston ring having the same nominal diameter as that of Example 1 (nominal diameter) were manufactured.
The three-piece type piston ring of Comparative Example 1 uses MC67 (JISB-8032 standard material) equivalent material as a spacer expander material for generating tension, and two rails arranged above and below the space expander. MC68 (JIS B-8032 standard material) equivalent material is used as the material of the member in the same manner as in Example 1, and the same ion plating as in the example is applied to the outer peripheral sliding portions of the two rail members in contact with the cylinder inner wall 7. What applied the film was used. The axial dimension of the three-piece type piston ring of Comparative Example 1 is 2.5 mm, the radial dimension is 2.8 mm, the tension is 5 N, the rail member 2 has an axial dimension of 0.35 mm, and the radial dimension. Was 2.0 mm. The shape of the abutment portion was a straight shape, and the abutment gap was set to 0.3 mm.

The two-piece type piston ring of Comparative Example 2 uses MC63 (JISB-8032 standard material) equivalent material as the material of the coil expander for generating tension, and MC68 (JIS B-8032 standard material) as the material of the outer peripheral ring. ) An equivalent material was used, and an outer peripheral sliding portion of the outer peripheral ring in contact with the cylinder inner wall 7 was applied with an ion plating film excellent in wear resistance as in the example. The two-piece piston ring of Comparative Example 2 had an axial dimension of 2.5 mm, a radial dimension of 2.5 mm, and a tension of 5N. The shape of the abutment portion was a straight shape, and the abutment gap was set to 0.3 mm.

As Comparative Example 3, a piston ring having the configuration shown in FIG. The piston ring of Comparative Example 3 has the same diameter as the piston ring according to Example 1, the same material, the same coating, the shape of the mating mouth portion, and the gap of the mating mouth portion, and the upper surface 5a and the lower surface of the ring groove 5 of the piston 4 5b and the contact portion between the upper surface 1a and the lower surface 1b of the resin ring member 1 from the position A of the maximum diameter of the ring inner peripheral portion F of the concave portion formed on the inner peripheral side of the ring body 1 in the axial direction of the ring The piston ring that exists between the intersecting position B where the extended line intersects with the upper and lower side surfaces E of the ring body 1 and the outer peripheral end D of the resin ring member 1 is the same as in the first embodiment. It was manufactured by a one-piece molding method using cast iron. In the structure of the piston ring of Comparative Example 3, the deformation of the resin ring main body 1 greatly affects the postures of the two rail members 2 in contact with the cylinder inner wall 7, and the outer peripheral sliding portions of the two rail members 2 are The cylinder inner wall may not be able to come into contact with an appropriate force or an appropriate posture, and sufficient sealing performance may not be exhibited.

As Comparative Example 4, a piston ring having the configuration shown in FIG. 1 of Patent Document 2 was manufactured so as to have the same diameter as the piston ring according to Example 1. The material of the elastic ring is polybenzimidazole (PBI) of the same material as in Example 1, and the piston ring main body combined with the elastic ring is MC68 (JISB-8032 standard material) equivalent material. For the outer peripheral sliding part in contact with the cylinder inner wall 7, the one provided with an ion plating film having the same excellent wear resistance as in Example 1 was used. The ring-shaped spring member disposed on the inner peripheral side of the elastic ring was made of the same MC63 (JISB-8032 standard material) equivalent material as in the examples and comparative examples. In the structure of the piston ring of Comparative Example 4, since the rigidity of the resin ring is too high, sufficient followability to circumferential undulation and deformation of the ring groove of the piston and insufficient followability to cylinder deformation are considered. Seal performance may not be achieved.

After assembling each of the piston rings of Examples and Comparative Examples manufactured as described above to the piston 4, the piston rings were assembled in a 4-cycle gasoline engine, and tests for evaluation of seal performance and followability were performed. The tension of each piston ring in the example and the comparative example was adjusted to be equal. The engine operating conditions for evaluation are as follows: an evaluation condition at a constant speed with an engine speed of 3500 revolutions per minute simulating traveling conditions on a highway, etc., and an engine revolutions per minute simulating traveling conditions in urban areas The evaluation was performed by performing a test for a predetermined time under two conditions of an evaluation condition based on an acceleration and deceleration pattern in which the number increased from 600 rotations to 4000 rotations and then decreased to 600 rotations.

FIG. 7 shows the results of the sealing performance and followability evaluation by the 4-cycle gasoline engine. FIG. 7 shows the ratio of oil consumption relative to Comparative Example 1 with Comparative Example 1 as a reference. Comprehensively evaluating the evaluation results, the piston ring according to the first and second embodiments of the present invention has a significantly reduced oil consumption as compared with the comparative examples, and without causing sticks, the side sealing performance and the cylinder inner wall Excellent trackability.

1 resin ring body 1a plastic ring side surface 1b resin ring lower surface 1c resin ring body of the base portion 1 d resinous ring thin width portion second rail member 3 tension ring 4 piston 5 ring groove of the main body of the body on the body 5a Ring groove upper surface 5b Ring groove lower surface 6 Piston oil relief hole 7 Cylinder inner wall 8 Resin material 9 Spacer expander 10 Coil expander A Maximum diameter position B of ring main body inner periphery Crossing position C Inner end of ring main body side surface D Ring body side outer edge E Ring body side F Ring body inner circumference

Claims (3)

A ring main body, a sliding member disposed on the outer peripheral side of the ring main body and in sliding contact with the inner wall of the cylinder, and a tension ring disposed on the inner peripheral side of the ring main body and biasing the ring main body in a direction of expanding the diameter. The ring body includes a base portion on the outer peripheral side, and an upper and lower thin portion extending from the upper side and the lower side of the base portion toward the inner peripheral side of the ring main body. And a ring formed of a resin or synthetic rubber having a concave portion on the inner peripheral side between the upper and lower thin width portions, and at least part of the upper side surface and the lower side surface of the ring body, and projecting downward, said upper and lower surfaces of the ring groove has a convex curved surface portion abutting the upper and lower side of the thin width portion, the sliding member and disposed on the outer peripheral side of the ring body, Re A rail member which is integrated in the grayed body, said the ring recess of the inner peripheral side of the body, a piston ring, characterized in that it comprises a tension ring for pressing the rail member to the cylinder inner wall through the ring body. The ring body inner circumferential end from the position where the line extending in the ring axial direction from the maximum diameter portion of the recess formed on the inner circumferential side of the ring body intersects the upper and lower side surfaces of the ring body. The piston ring according to claim 1 , wherein: The piston ring according to claim 1 or 2 , wherein a resin having a lower elastic modulus than that of the ring body is disposed between the ring body and the rail member inserted into the ring body.