JP5222650B2 - piston ring - Google Patents

Description

  The present invention relates to a piston ring used in an internal combustion engine, and more particularly to a piston ring that can effectively prevent an aluminum adhesion (welding) phenomenon to the piston ring.

  In general, a reciprocating piston is provided with a pressure ring and an oil ring as a piston ring. This pressure ring has a function of preventing a phenomenon (blow-by) that high-pressure combustion gas flows out from the combustion chamber side to the crank chamber side. On the other hand, the oil ring mainly has a function of suppressing a phenomenon (oil up) in which excess lubricating oil on the inner wall of the cylinder enters the combustion chamber side from the crank chamber side and is consumed. As a conventional standard piston ring combination, a total of three piston ring combinations of two pressure rings including a top ring and a second ring and one oil ring are known.

  In recent years, the quality required for piston rings has been increasing more and more with the reduction in weight and output of internal combustion engines. Conventionally, piston rings for internal combustion engines have been subjected to wear resistant surface treatment such as nitriding treatment, ion plating treatment or hard chrome plating treatment on the sliding surface as means for improving the durability.

  Among these surface treatments, the nitriding treatment is particularly noticeable and widely used as a surface treatment for piston rings used under severe operating conditions because it exhibits excellent wear resistance.

  However, although the piston ring formed with the nitriding layer is excellent in wear resistance, when it is mounted on an aluminum alloy piston, there is a tendency that the ring groove wear of the piston increases. Further, as shown in FIGS. 1A to 1C, aluminum agglomeration in which aluminum on the groove lower surface 11 of the aluminum alloy piston 10 adheres to the lower surface 3 of the piston ring 1 due to wear of the piston ring groove. Wearing occurs (FIG. 1 (c)).

  FIGS. 2A to 2C are charts obtained by a stylus type surface roughness tester showing changes in the surface state of the upper surface 2 and the lower surface 3 of the ring groove of the piston. As shown in FIG. 2, the surface state of the upper surface 2 and the lower surface 3 of the ring groove of the piston is changed from a normal state (FIG. 2 (a)) to a rough piston groove state (FIG. 2 (b)), an aluminum adhesion state ( It changes to FIG.2 (c)).

  2A to 2C, the horizontal axis indicates the position of the piston, and the vertical axis indicates the undulation of the piston groove. In the figure, (F) indicates the front direction, (AT) indicates the anti-thrust direction, (R) indicates the rear direction, and (T) indicates the thrust direction.

  3A to 3C show an aluminum adhesion mechanism, in which an oxide film 8 in which a lower surface 3 of a piston ring 1 and a groove lower surface 11 of an aluminum alloy piston 10 are formed on both surfaces, respectively. (Fig. 3 (a)), the stress of the oxide film 8 at the contact portion is locally increased and the oxide film 8 is destroyed, and the lower surface 3 of the piston ring 1 is broken. Fe and Al on the groove lower surface 11 of the piston 10 made of aluminum alloy are joined (FIG. 3B), and the aluminum alloy 20 is welded to the lower surface 3 of the piston ring 1 (FIG. 3C). An enlarged view of the aluminum adhesion part is shown in FIG. In FIG. 4, 20 indicates the adhered aluminum, and 21 indicates the joint between Al and Fe.

  As described above, when local wear (also referred to as piston groove roughening) due to this welding phenomenon occurs in a certain portion of the piston groove as the piston ring moves up and down, the internal combustion engine is sealed by blow-by gas blow-through. The output decreases. Since this phenomenon occurs in a short time under the ring groove of the piston and has a great influence on the durability of the internal combustion engine, many countermeasures for wear of the piston groove have been proposed.

  For example, to prevent direct contact between the piston and the piston ring as a measure against piston groove wear, the piston is treated with an anodized film, plating or matrix strengthening (in the piston), and to the piston ring. As countermeasures, phosphate coating treatment, plating treatment is performed, or, as shown in FIGS. 5A and 5B, the surfaces of the piston 10 and the piston ring 1 are coated with resin coating 8 (for example, deflick (( (Coating process manufactured by Kawamata Laboratories Co., Ltd.).

  In order to solve the above problem, a wear-resistant treatment layer such as a nitrided layer or a chrome plating layer is formed on the upper and lower surfaces or the lower surface of the piston ring, and solid lubrication is applied to the surface of the wear-resistant treatment layer. A piston ring having a polybenzimidazole resin film containing an agent has been developed (see Patent Document 1).

Furthermore, piston rings whose surfaces are coated with a heat-resistant resin containing a solid lubricant have been developed even by those other than the applicant of the present application (see, for example, Patent Documents 2 and 3).
Japanese Patent Application Laid-Open No. 07-063266 JP-A-10-246149 JP 11-246823 A

  However, although the above-described conventional measures against piston groove wear have the effect of preventing aluminum adhesion at the initial stage when the piston is used, the medium-to-long life is insufficient, and further improvement in durability is desired. Yes.

More specifically, for example, Patent Document 1 discloses a surface film composed of a polybenzimidazole resin and a solid lubricant (graphite or MoS ₂ ). The liquid resin is easy to oxidize and deteriorates with time. In addition, it may be difficult to stabilize the quality over a long period of time.

Further, Patent Document 2 discloses a surface film composed of polyamideimide resin or polyimide resin and a solid lubricant (graphite, MoS ₂ , WS ₂ , polytetrafluoroethylene). Then, aluminum adhesion cannot be prevented sufficiently, and the high cost becomes a problem.

Further, Patent Document 3 discloses a surface film composed of polyamideimide resin or polyimide resin and MoS ₂ as a solid lubricant and antimony oxide (Sb ₂ O ₃ ). Aluminum adhesion cannot be sufficiently prevented, and antimony oxide is harmful to the environment and is not preferred for use.

  The present invention has been made in view of such a situation, and improves wear resistance, effectively prevents aluminum adhesion to the piston ring, and further the surface coating from the piston ring body. The main object is to provide a piston ring that can effectively prevent peeling.

The first invention of the present application for solving the above-mentioned problems is composed of a piston ring body and a surface film formed on either the upper surface or the lower surface of the piston ring body, or on both the upper surface and the lower surface of the piston ring. The surface coating is disposed on the outermost surface layer composed of a heat-resistant resin and a metal powder contained in the heat-resistant resin, and is disposed closest to the piston ring body, and the heat-resistant resin and the heat-resistant resin. and the base layer consisting of consisting of metal powders containing the at least chromatic in the outermost layer, and the metal powder contained in the basal layer, copper (Cu) based powder, nickel (Ni) powder Nickel alloy powder, lead (Pb) -based powder, tin (Sn) -based powder, or silicon (Si) -based powder, and the heat-resistant resin constituting the outermost surface layer and the base layer is A self-lubricating metal is contained, and the self-lubricating metal contained in the outermost surface layer and the base layer is one of molybdenum disulfide, tungsten disulfide, or graphite, and the whole base layer On the other hand, the content of the metal powder contained in the base layer is 40% by mass or less, and the content of the self-lubricating metal contained in the base layer is 5% by mass or less. The content of the metal powder contained in the outermost surface layer is 40 to 80% by mass, and the content of the self-lubricating metal contained in the outermost surface layer is 2 to 10% by mass with respect to the whole. The average particle size of the metal powder and self-lubricating metal contained in the base layer is 5 μm or less, and the average particle size of the metal powder and self-lubricating metal contained in the outermost surface layer is 5-40 μm, the above Surface layer, and the shape of the metal powder contained in the base layer is flaky,該鱗piece shaped metal powder is characterized by being arranged to overlap in the thickness direction of the surface film.

  Further, the second invention of the present application for solving the above-mentioned problems is a surface coating formed on the piston ring body and either the upper surface or the lower surface of the piston ring body, or both the upper surface and the lower surface of the piston ring. The surface coating is disposed on the outermost surface layer composed of a heat-resistant resin and a metal powder contained in the heat-resistant resin, and is disposed closest to the piston ring body. A base layer comprising at least a metal powder contained in the heat-resistant resin, and the content of the metal powder contained in the base layer is compared with the content of the metal powder contained in the outermost surface layer. It is characterized by few.

  The heat resistant resin may be a polyamideimide resin or a polyimide resin.

  According to the first invention of the present application, the outermost surface layer composed of the heat-resistant resin and the metal powder contained in the heat-resistant resin is formed on one or both of the upper surface and the lower surface of the piston ring, whereby Abrasion can be imparted and part of the ring groove of the aluminum alloy piston can be prevented from peeling off and adhering to the piston ring, and the base layer made of heat-resistant resin can be connected to the outermost surface layer via the base layer. By firmly adhering the piston ring base material, it is possible to prevent the surface film from peeling from the piston ring body.

  In addition, according to the second invention of the present application, by reducing the content of the metal powder contained in the base layer relative to the content of the metal powder contained in the outermost surface layer, the piston ring body and the surface coating It is also possible to maintain the adhesion of the surface, and it is possible to prevent the surface film from peeling off from the piston ring body. Further, even when the outermost surface layer is removed by wear and the base layer is exposed, the wear resistance of the surface film can be maintained by the wear resistance effect of the base layer.

  In the above-mentioned measures against piston ring groove wear, in other words, aluminum adhesion prevention measures (see the column of the prior art), a surface film containing a solid lubricant is formed for the purpose of imparting lubricity to the surface of the piston ring body. On the other hand, the present invention is characterized in that a surface film containing metal powder is formed instead of a solid lubricant.

  Conventionally, attention has been paid to improving the lubricity of the surface of the piston ring as a measure for reducing the wear of the piston ring groove as much as possible. If this improves the lubricity of the surface of the piston ring, the aggressiveness of the piston ring against the piston ring groove can be reduced accordingly, and as a result, wear of the piston ring groove will be prevented. .

  However, this measure does not cause a problem at the initial stage where the surface film that contributes to lubricity is sufficiently present, but after a long period of time, the surface film itself may be worn away and peeled off. High, after wear and peeling, the lubricity is lost and the exposed piston ring body causes wear of the piston ring groove.

  The present inventor pays attention to this problem, and in order to solve the problem, in order to secure lubricity by the heat-resistant resin constituting the surface film and to maintain the lubricity by the heat-resistant resin for a longer time, the surface film It is conceived that metal powder is dispersed and blended in the outermost surface layer constituting the surface, and that the metal powder imparts wear resistance to the surface film, and further, by providing a base layer made of a heat-resistant resin, It is conceived that adhesion is imparted to the base layer that joins the outermost surface layer. That is, the present invention has a different concept from the conventional one, and the metal powder contained in the outermost surface layer in the present invention has a main role of imparting wear resistance to the outermost surface layer constituting the surface film. The heat-resistant resin constituting the base layer has a main role of providing adhesion to the base layer.

  According to the present invention, lubricity can be imparted to the surface of the piston ring by the heat resistant resin of the outermost surface layer constituting the surface coating, and the surface coating formed on the piston ring surface by the metal powder is resistant to the surface coating. Piston ring with a surface coating, which provides wear resistance and suppresses initial wear by maintaining adhesion to the base layer with the heat resistant resin of the base layer that constitutes the surface coating. Therefore, the lubricity by the heat-resistant resin can be functioned for a long time.

  First, the piston ring of the first invention of the present application will be specifically described with reference to the drawings.

  FIG. 6 is a cross-sectional view of the piston ring of the first invention of the present application.

  7A is an enlarged cross-sectional view of the vicinity of the upper surface of the piston ring shown in FIG. 6, and FIG. 7B is an enlarged front view of the upper surface of the piston ring shown in FIG.

  As shown in FIG. 6, the piston ring 60 of the present invention is composed of a piston ring main body 61 and a surface coating 62 formed on one or both of the upper surface and the lower surface (both in FIG. 6). The surface film 62 is disposed at a position farthest from the piston ring body 61 on the sliding surface side, and includes an outermost surface layer 64 composed of a heat resistant resin 65 and a metal powder 67 contained in the heat resistant resin, It is arranged closest to the piston ring main body 61 and is composed of a base layer 63 made of a heat resistant resin 66.

  The material of the piston ring body 61 of the present invention is not particularly limited, and any material can be used. For example, steel (steel material) can be mainly used as the material, and SUS440, SUS410, SUS304, etc., or 8Cr steel, 10Cr steel, SWOSC-V, SWRH material, etc. can be used as stainless steel. it can. Further, as a kind of piston ring, not only a top ring that functions as a so-called pressure ring but also a second ring that is the same pressure ring can be used, and further, the present invention can be applied to an oil ring.

  The outermost surface layer 64 is provided to improve the wear resistance of the surface film 62 and prevent the aluminum adhesion phenomenon to the piston ring, and is contained in the heat resistant resin 65 and the heat resistant resin. And metal powder 67.

  The heat-resistant resin 65 constituting the outermost surface layer 64 is mainly intended to impart lubricity to the piston ring surface, while the metal powder 67 constitutes the outermost surface layer 64 constituting the surface film 62 in which it is contained. It is intended to impart wear resistance to the heat-resistant resin 65 and thereby maintain the lubricity due to the heat-resistant resin 65 for a long time.

  The heat-resistant resin 65 constituting the outermost surface layer 64 can withstand the environment (temperature) in which the piston ring is used, has lubricity, and holds and fixes a metal powder 67 described later. There is no particular limitation as long as it is a resin that can be used. Specifically, polyamide imide (PAI) resin, polyimide (PI) resin, and the like can be given.

  On the other hand, the metal powder 67 constituting the outermost surface layer 64 of the present invention is intended to impart wear resistance to the surface film 62 contained therein, and a metal capable of achieving such an object. As long as the powder 67 is used, the material of the metal powder 67 is not particularly limited.

  However, in the present invention, the metal powder serves to prevent the above-mentioned heat-resistant resin from being worn, while attacking the piston ring groove which is the counterpart material must be avoided. Then, as the material of the metal powder 67, copper (Cu) -based powder, nickel (Ni) powder, nickel alloy powder, which have excellent wear resistance and low attack to the piston ring groove, which is the counterpart material, are used. Lead (Pb) -based powder, tin (Sn) -based powder, silicon (Si) -based powder and the like are preferable.

  The shape of the metal powder 67 is not particularly limited, and may be a regular shape such as a scale shape, a spherical shape, or a polygonal shape, or an indefinite shape. However, it is necessary to avoid attacking the piston ring groove, which is the counterpart material, with the metal powder 67. From this point of view, it is not preferable to have a polygonal shape, such as a scaly shape as shown in FIG. A spherical shape (not shown) is preferable. It is possible to prevent the piston ring groove from being damaged by arranging the metal powder 67 in a scale shape or a spherical shape and arranging the metal powder 67 so as to overlap in the thickness direction of the surface film as shown in FIG.

  When the metal powder 67 has a scale shape or a spherical shape, the size is not particularly limited, but the average particle size is preferably 5 to 40 μm. By setting the particle size of the metal powder 67 contained in the outermost surface layer 64 within the above range, the wear resistance of the outermost surface layer 64 can be further improved. The particle size of the scaly or spherical metal powder 67 is the length of the symbol r shown in FIG. 7B and means the length of the major axis of the scaly.

  In the outermost surface layer 64 constituting the surface film 62 of the present invention, regarding the content of the metal powder 67 with respect to the heat resistant resin 65, the heat resistant resin 65 exhibits sufficient lubrication performance, and the metal powder 67 exhibits wear resistance performance. However, specifically, the content of the metal powder 67 is preferably 40 to 80% by mass, particularly 50 to 60% by mass. preferable. When the content of the metal powder 67 is less than 40% by mass, reduction / extinction due to abrasion of the surface film cannot be sufficiently prevented, and aluminum adhesion cannot be sufficiently prevented. On the other hand, when the content of the metal powder 67 exceeds 80% by mass, the flexibility of the entire surface film is lowered, and it becomes difficult to fix the metal powder 67 with the heat-resistant resin 65, and the metal powder 67 is detached. There is a risk that.

  It is preferable that the area ratio (refer FIG.7 (b)) which the metal powder 67 in the outermost surface layer 64 which comprises the piston ring of this invention crimps is 6 to 74%. By limiting the area ratio within this range, the balance between the heat-resistant resin 65 and the metal powder 67 is improved, and the respective effects can be sufficiently exhibited.

  As shown in FIG. 8, the heat-resistant resin 65 preferably contains a self-lubricating metal 68, which is preferably dispersed uniformly. The self-lubricating metal 68 is preferably molybdenum disulfide, tungsten disulfide, or graphite. Thus, by adding the self-lubricating metal 68, it is possible to improve the initial familiarity of aluminum adhesion. As a specific content rate, the content rate of the self-lubricating metal 68 with respect to the entire outermost surface layer 64 is preferably 2 to 10% by mass, and more preferably 3 to 5% by mass. (In this case, when the content of the metal powder 67 made of a predetermined material is 40 to 80% by mass, the remainder becomes the heat resistant resin 65). By forming the surface film 62 containing the self-lubricating metal 67 in addition to the metal powder 67 made of a predetermined material on the upper and lower surfaces of the piston ring, initial conformability and wear resistance with the piston material made of an aluminum material are improved. As a result, the occurrence of aluminum adhesion can be prevented, and a piston ring excellent in durability can be provided.

  As the self-lubricating metal 68, the same effects can be obtained by using tungsten selenide, molybdenum selenide, boron nitride, or a fluororesin (such as polytetrafluoroethylene) in addition to those listed above.

  The base layer 63 is provided to closely contact the outermost surface layer 64 and the piston ring body 61 described above, and to prevent the surface film 62 from peeling off from the piston ring.

  The heat-resistant resin 65 constituting the base layer is used for imparting adhesion to the base layer, and the material of the heat-resistant resin 66 constituting the base layer 63 is particularly limited as long as the above effect can be obtained. In other words, a conventionally known material can be appropriately selected and used. Specific examples of such heat resistant resin 66 include polyamide imide (PAI) resin and polyimide (PI) resin. Since the adhesion between the base layer 63 made of such resin and the piston ring main body 61 and the outermost surface layer 64 is high, the adhesion between the piston ring main body 61 and the outermost surface layer 64 is improved, and the surface coating from the piston ring 62 can be prevented from peeling off.

  The method for forming the surface film 62 in the present invention is not particularly limited. For example, the base layer 63 is formed by applying a heat-resistant resin 66 to the surface of the piston ring body 61 by spray coating, dip coating, electrostatic coating, or the like. Then, the outermost surface layer 64 may be formed by adding the aforementioned metal powder 67 to the heat resistant resin 65 and applying it to the surface of the base layer 63. In addition, the surface film 62 may be subjected to post-treatment such as heating and baking as necessary.

  The film thickness of the outermost surface layer 64 in the present invention formed by such a method is set to 5.0 to 11.0 μm, and the film thickness of the base layer 63 is set to about 0.1 to 2.0 μm. preferable.

  By setting the outermost surface layer 64 and the base layer 63 constituting the surface film 62 to such a film thickness, the adhesion with the base material is further improved in the base layer, and the wear resistance is further maintained in the outermost surface layer. be able to.

  As described above, according to the first invention of the present application, by providing the outermost surface layer 64 and the base layer 63 as the layers constituting the surface film 62, the outermost surface layer 64 improves the wear resistance of the surface film 62. The aluminum adhesion phenomenon to the piston ring can be prevented, and the surface film 62 can be prevented from being peeled off from the piston ring by the base layer 63.

  Next, the second invention of the present application will be described.

  FIG. 8 is a cross-sectional view of the piston ring of the second invention of the present application.

  9A is an enlarged cross-sectional view of the vicinity of the upper surface of the piston ring shown in FIG. 8, FIG. 9B is an enlarged front view of the outermost surface layer surface of the piston ring shown in FIG. 8, and FIG. It is an enlarged front view of the basal layer surface of the piston ring shown in FIG.

  In the second invention of the present application, the heat resistant resin 66 constituting the base layer 63 contains the metal powder 67, and the content of the metal powder 67 contained in the base layer 63 is contained in the outermost surface layer 64. In comparison with the content of the metal powder 67, the piston ring body 61 constituting the piston ring 60, the outermost surface layer 64 and the heat-resistant resin 66 constituting the base layer 63 are characterized by: This corresponds to FIG. 6 and FIG. 7 described above and will not be described in detail.

  When the metal powder 67 contained in the base layer 63 settles on the piston ring main body 61, the adhesion rate between the base layer 63 and the piston ring main body 61 is lowered. Therefore, the content of the metal powder 67 contained in the base layer 63 Is preferably smaller than the content of the metal powder 67 contained in the outermost surface layer 64.

  Thus, by reducing the content of the metal powder 67 in the base layer 63, the piston ring main body 61 and the base layer 63, and the outermost surface layer 64 and the base layer 63 are obtained by the effect of the heat-resistant resin 66 for providing adhesion. The adhesion of the surface coating 62 can be improved, the peeling of the surface coating 62 from the piston ring can be prevented, and the wear resistance of the surface coating 62 can be maintained by increasing the content of the metal powder 67 in the outermost surface layer 64. it can. Further, since the base layer 63 itself has wear resistance due to the metal powder 67 contained in the base layer 63, even if the outermost surface layer 64 disappears due to wear, the base containing no metal powder is contained. A certain amount of wear resistance can be maintained compared to the layer.

  As the metal powder 67 contained in the heat-resistant resin 66 constituting the base layer 63, as with the metal powder 67 contained in the outermost surface layer 64, copper (Cu) -based powder and nickel (Ni) powder which are metal powder powders. Nickel alloy powder, lead (Pb) -based powder, tin (Sn) -based powder or silicon (Si) -based powder. The shape and surface area of the metal powder 67 correspond to those shown in FIGS. There is no description.

  In the base layer 63 constituting the surface film 62 of the present invention, the content of the metal powder 67 with respect to the heat resistant resin 66 is such that the heat resistant resin 66 exhibits the adhesion performance between the piston ring body 61 and the outermost surface layer 64, In addition, the metal powder 67 can be appropriately set with a balance that can exhibit wear resistance, but the base layer needs to join the piston ring body and the outermost surface layer. The content of the metal powder 67 in the base layer 63 is preferably smaller than the content of the metal powder 67 in the surface layer 64, and the content of the metal powder 67 contained in the base layer 63 is the mass of the entire base layer 63. More preferably, it is 40% by mass or less. If the content of the metal powder 67 is larger than 40% by mass, the content of the resin component in the base layer 63 is reduced, so that the adhesion performance of the base layer 63 is lowered and the surface film 62 is effectively peeled from the piston ring. Therefore, the surface film 62 may be peeled off.

  In addition, the heat-resistant resin constituting the base layer 63 preferably contains a self-lubricating metal 68 as shown in FIGS. 8 and 9, and these are preferably dispersed uniformly. The self-lubricating metal 68 is preferably any one of molybdenum disulfide, tungsten disulfide, and graphite, like the self-lubricating metal 68 contained in the outermost surface layer 64 described above. Thus, by adding the self-lubricating metal 68, it is possible to improve the initial familiarity of aluminum adhesion.

  In order to prevent the self-lubricating metal 68 of the base layer 63 from sinking to the piston ring body 61 and reducing the adhesion performance of the base layer 63, the content of the self-lubricating metal 68 of the base layer 63 is determined as follows. It is preferable that the content of the self-lubricating metal 68 is 64, and the content of the self-lubricating metal 68 with respect to the entire base layer 63 is more preferably 5% by mass or less. (In this case, if the content of the metal powder 67 made of a predetermined material is 40% by mass or less, the remainder becomes the heat resistant resin 66). If the content of the self-lubricating metal is greater than 5%, the initial conformability and wear resistance with the piston material made of aluminum can be improved, but as described above, the self-lubricating metal settles on the piston ring surface. By doing so, the adhesion of the base layer may be reduced.

  Even if the outermost surface layer disappears by forming the base layer 63 containing the self-lubricating metal 68 in addition to the metal powder 67 made of a predetermined material on the upper and lower surfaces of the piston ring, aluminum The initial conformability and wear resistance with the piston material made of the material can be maintained, and the metal powder 67 contained in the base layer 63 and the self-lubricating metal 68 are compared with those contained in the outermost surface layer 64. Therefore, the content of the heat-resistant resin 66 for imparting adhesion can be ensured. As a result, the occurrence of aluminum adhesion is prevented, the durability is excellent, and the surface film 62 is peeled off. A piston ring can be provided.

  As the self-lubricating metal, the same effect can be obtained by using tungsten selenide, molybdenum selenide, boron nitride, or a fluororesin (such as polytetrafluoroethylene) in addition to those listed above.

  Since the adhesion decreases when the average particle size of the metal powder 67 and the self-lubricating metal 68 contained in the base layer 63 is increased, the metal powder 67 and the self-lubricating metal 68 contained in the base layer 63 are reduced. The average particle size is preferably smaller than the average particle size of the metal powder 67 and the self-lubricating metal 68 of the outermost surface layer 64. Further, since the adhesion of the base layer is remarkably lowered when the average particle size is 5 μm or more, the average particle size of the metal powder 67 and the self-lubricating metal 68 contained in the base layer 63 is preferably 5 μm or less. . Thus, by making the average particle diameter of the metal powder 67 and the self-lubricating metal 68 contained in the base layer 63 5 μm or less, the adhesion of the base layer is improved, and the piston ring main body 61 and the surface coating 62 are separated from each other. Adhesion can be further improved.

  According to the second invention described above, the base layer 63 can exert a certain effect on the wear resistance by containing the metal powder 67 in the base layer 63, and the outermost surface layer 64 disappears. Even in this case, the wear resistance of the surface film 62 can be maintained.

  Further, by reducing the content of the metal powder 67 contained in the base layer 63 as compared with that contained in the outermost surface layer 64, the adhesion performance of the base layer 63 can be maintained. It is possible to prevent the surface film 62 from peeling off.

  Further, by reducing the average particle size of the metal powder 67 and the self-lubricating metal 68 contained in the base layer 63 as compared with that contained in the outermost surface layer 64, the adhesion and the maximum of the base layer 63 are improved. The wear resistance of the surface layer 64 can be further improved.

  The piston ring of the present invention will be described more specifically with reference to examples.

(Examples 1 to 29, Comparative Examples 1 to 6)
A member corresponding to the piston ring main body was prepared using JIS SWOSC-V equivalent material. The dimensions of the piston ring were as follows: outer diameter: 71 mm, ring radial width (a1 dimension): 2.55 mm, and ring axial width (h1 dimension): 1.2 mm. The composition of the JIS SWOSC-V equivalent material is as follows: C: 0.55% by mass, Si: 1.4% by mass, Mn: 0.6% by mass, P: 0.02% by mass, S: 0.02 % By mass, Cr: 0.65% by mass, Cu: 0.08% by mass, the balance being Fe and inevitable impurities.

  Polyamideimide resin is used as a heat-resistant resin on both the upper and lower surfaces of the member made of the above material, and copper-based powder is contained as a metal powder, and molybdenum disulfide is contained as a self-lubricating metal. A base layer having a thickness of 2.0 μm was formed. Next, an outermost surface layer having a thickness of 8.0 μm was formed on the base layer by a spray method using the same material as the base layer. The average particle diameter of the metal powder, the content of the metal powder and the self-lubricating metal with respect to the entire base layer and the outermost surface layer, and the average particle diameter of the metal powder are as shown in Table 1, respectively.

  In Comparative Example 1, the outermost surface layer containing 2% by mass of molybdenum disulfide in the polyamide-imide resin without containing the copper-based powder, 20% by mass of copper-based powder in the polyamide-imide resin, and molybdenum disulfide. When the outermost surface layer and the base layer are formed on the test piece, the wear amount of the piston material and the wear amount of the piston ring material after the sliding test is 100, The amount was calculated.

  Each piston ring test piece formed in this way is referred to as Examples 1 to 29 and Comparative Examples 1 to 6 (see Table 1).

  A sliding test was performed on the test pieces of the above Examples and Comparative Examples.

<Slip test>
This test was performed using a high-temperature valve seat wear tester 101 shown in FIG. The test conditions were: stroke: 4 mm, repetition rate: 500 times / min, ring rotation speed: 3 rpm, test time: 7 hours, piston temperature: about 250 ° C., piston material: aluminum alloy (AC8A).

  In the sliding tapping test, the piston material 103 is fixed to the testing machine 101 so as not to move in the axial direction, the piston ring test piece 102 is mounted on the piston material 103 concentrically, and the internal phase of the piston ring test piece 102 is determined. This test is performed by reciprocating the cast iron circular bar 105 provided on the side in the axial direction, and is a test method in which an operation mode is given in which the piston material 103 is struck while rotating the piston ring test piece 102. The testing machine 101 has a heater 104 for heating the test material, and can reproduce the high temperature state during combustion in the engine without actually burning the fuel, and simulates the state change of the piston material. Can do.

  The wear amount on the piston side and the wear amount on the piston ring side were evaluated by the test. The amount of wear was measured by measuring the level difference with a surface roughness meter, and the amount of wear was calculated when the amount of wear in Comparative Example 1 was set to 100. The piston material wear amount ratio and the piston ring material wear amount ratio were 90. “◎” when the following conditions are satisfied, and “○” when the piston material wear ratio and the piston ring wear ratio are greater than 90 and less than 95, and the piston wear ratio and the piston ring wear ratio are 95 or more. The case where it was was set as "x".

  The evaluation results are shown in Table 1 below.

  When Examples 1 to 5 shown in Table 1 are compared with Comparative Examples 1 to 3, the wear resistance of Examples of the present invention containing metal powder in the outermost surface layer is extremely good, and Examples 6 to 29 and Comparative Examples 4 to 6 show that the wear resistance of the embodiment of the present invention in which the content of the metal powder contained in the base layer is less than the content of the metal powder contained in the outermost surface layer is extremely high. It is clear from the numerical values of the wear amount ratios of the piston material and the piston ring material that it is good.

It is explanatory drawing of an aluminum adhesion phenomenon, (a) is a perspective view of a piston, (b) is an enlarged perspective view of a ring groove and a piston ring of a piston, (c) is an enlarged perspective view showing aluminum adhesion to a piston ring. FIG. (A)-(c) is a figure which shows the mode of the change of the surface state of the shape surface of a ring groove of a piston, and a lower surface. (A)-(c) is sectional drawing which shows an aluminum adhesion mechanism. It is an enlarged view of an aluminum adhesion part. It is sectional drawing which shows the conventional resin coating process. It is sectional drawing of the piston ring of 1st invention of this application. (A) is an expanded sectional view of the surface film vicinity of the piston ring shown in FIG. 6, (b) is an enlarged front view of the outermost surface layer surface of the piston ring shown in FIG. It is sectional drawing of the piston ring of 2nd invention of this application. (A) is an expanded sectional view near the surface film of the piston ring shown in FIG. 8, (b) is an enlarged front view of the outermost surface layer surface of the piston ring shown in FIG. 8, and (c) is FIG. It is an enlarged front view of the base layer surface of the piston ring shown in FIG. This is a high temperature valve seat wear tester.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 60 ... Piston ring 2 ... Upper surface of piston ring 3 ... Lower surface of piston ring 10 ... Piston 61 ... Piston ring main body 62 ... Surface coating 63 ... Base layer 64 ... Outermost surface layer 65, 66 ... Heat-resistant resin 67 ... Metal powder 68 ... Self-lubricating metal

Claims (2)

A piston ring comprising a piston ring body and a surface coating formed on either the upper surface or the lower surface of the piston ring body, or both the upper surface and the lower surface of the piston ring,
The surface coating is disposed on the outermost surface layer composed of a heat-resistant resin and a metal powder contained in the heat- resistant resin, and closest to the piston ring body, and the heat-resistant resin and the metal powder contained in the heat- resistant resin. A base layer consisting of
At least have a,
The metal powder contained in the outermost surface layer and the base layer is a copper (Cu) powder, nickel (Ni) powder, nickel alloy powder, lead (Pb) powder, tin (Sn) powder or silicon ( Si) based powder,
The heat-resistant resin constituting the outermost surface layer and the base layer further contains a self-lubricating metal,
The self-lubricating metal contained in the outermost surface layer and the base layer is either molybdenum disulfide, tungsten disulfide, or graphite,
The content of the metal powder contained in the base layer is 40% by mass or less and the content of the self-lubricating metal contained in the base layer is 5% by mass or less with respect to the entire base layer. ,
The content of the metal powder contained in the outermost surface layer is 40 to 80% by mass with respect to the entire outermost layer, and the content of the self-lubricating metal contained in the outermost layer is 2 to 2%. 10% by weight,
The metal powder contained in the base layer and the average particle size of the self-lubricating metal are 5 μm or less,
The metal powder contained in the outermost surface layer, and the average particle size of the self-lubricating metal is 5 to 40 μm,
The shape of the metal powder contained in the outermost surface layer and the base layer is scaly, and the scaly metal powder is disposed so as to overlap in the thickness direction of the surface film. Piston ring to do.   The piston ring according to claim 1, wherein the heat-resistant resin is a polyamide-imide resin or a polyimide resin.

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