JP2006275269A - Combined sliding member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combined sliding member formed of a piston ring and a cylinder liner matching reduction in a coefficient of friction in response to reduction of friction in an internal combustion engine, and having excellent scuff resistance. <P>SOLUTION: This combined sliding member 30 is formed of the piston ring 10 and the cylinder liner 20, and the combined sliding member 30 formed of the piston ring 10 with a surface roughness Rz of 0.3 to 2.5 μm in a sliding surface 11, initial friction height Rpk≤0.15 μm, effective load roughness Rk of 0.10 to 0.50 μm, oil sump depth Rvk of 0.20 to 1.0 μm, oil sump depth ratio K(=Rvk/Rk) of 10.0 to 4.0 and the cylinder liner 20 with a surface roughness Rz of 0.2 to 0.8 μm in a sliding surface 21 for solving the described problem. About surface condition of the piston ring 10, shot blast is performed to the sliding surface 11 to form a film with a physical vapor deposition method, and the surface of the piston ring 10 is desirably ground for formation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a combined sliding member composed of a piston ring and a cylinder liner, corresponding to the reduction in friction of an internal combustion engine.

  Due to the recent demand for higher output of internal combustion engines, severe conditions regarding the characteristics of the piston ring and the cylinder liner that is in sliding contact with the piston ring are required.

  Under these circumstances, in order to improve the initial compatibility with the piston ring, in the cylinder liner, the surface roughness Rz of the sliding surface is generally set to about 2 to 3 μm. Further, a phosphate film is formed in the vicinity of the top dead center of the top ring of the cylinder liner, and the surface roughness Rz of the phosphate film is specified to be 0.5 to 3.2 μm. Cylinder liners that reduce the lubricant consumption and improve the seizure resistance (also referred to as scuff resistance) by defining the surface roughness Rz of the portion as 0.6 to 1.8 μm are known (for example, (See Patent Document 1).

Moreover, in the combination of the piston ring and the cylinder liner, a piston ring having a sliding surface with a surface roughness Rz of 0.5 to 1.0 μm, a surface roughness Rz of 0.5 to 1.5 μm and a DIN4776 standard Cylinder liner having a sliding surface with an initial wear height Rpk based on 0.05 to 0.2 μm, an effective load roughness Rk of 0.2 to 0.6 μm, and an oil sump depth Rvk of 0.10 to 0.35 μm There is known a combination sliding member having (see, for example, Patent Document 2). This piston ring is formed by forming a film on a sliding surface by an ion plating method.
Japanese Patent Laid-Open No. 11-153059 JP 2004-116707 A

  However, in such a piston ring disclosed in Patent Document 2, a surface on which physical vapor deposition is performed in order to finish the surface roughness Rz of the sliding surface to 1 μm or less in consideration of friction reduction and opponent attack reduction. In some cases, there was no oil accumulation and seizure was likely to occur at the initial familiarization stage. Similarly, if the inner surface (bore) roughness of the cylinder liner is small, seizure may easily occur.

  Furthermore, in the combination of the piston ring and the cylinder liner disclosed in the cited document 2, further reduction of friction is required. In other words, the ion plating film on the piston ring has no oil retaining property, but has excellent heat resistance and wear resistance, so the surface roughness is reduced and the oil pool mechanism is provided by the honing process on the cast iron cylinder liner material. By having it, excellent sliding characteristics were obtained. In order to further reduce the friction of the sliding member, it is desired to reduce the surface roughness of the cylinder liner.

  On the other hand, if the surface roughness of the piston ring is made fine and the surface roughness of the cylinder liner is also made fine, the friction is reduced, but conversely, the oil retaining property is lowered, so that there is a disadvantage that scuffing is likely to occur. Further, since the piston ring and the cylinder liner reciprocate through the piston, it is also desired that the surface roughness be roughened as disclosed in Patent Document 1, particularly in the vicinity of the top dead center of the piston. Making the surface roughness of the sliding surface of the cylinder liner finer and further performing the surface treatment in part causes a significant increase in cost.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a combined sliding member composed of a piston ring and a cylinder liner, corresponding to the reduction in friction of an internal combustion engine, having a low coefficient of friction and excellent scuff resistance.

  In order to achieve the above object, the present invention is a combined sliding member comprising a piston ring and a cylinder liner, wherein the sliding surface has a surface roughness Rz of 0.3 to 2.5 μm and an initial wear height Rpk ≦ 0. .15 μm, effective load roughness Rk 0.10 to 0.50 μm, oil sump depth Rvk 0.20 to 1.0 μm, oil sump depth ratio K (= Rvk / Rk) 1.0 to 4.0 piston ring And a cylinder liner having a surface roughness Rz of 0.2 to 0.8 μm on the sliding surface.

  In the combined sliding member of the present invention, the piston ring has a base material made of spheroidal graphite cast iron, and the area ratio of the spherical graphite in the cross section of the base material is 5 to 20%, and a sliding surface on which a hard film is formed In this case, it is preferable that the hard coating is polished by physical vapor deposition after shot blasting, removing graphite distributed on the sliding surface and sinking into the piston ring. In this case, the thickness of the film formed on the sliding surface of the piston ring is preferably 5 to 70 μm.

  According to the combination sliding member according to claim 1, since the combination sliding member is constituted by the piston ring and the cylinder liner having the surface properties, the friction coefficient at the time of sliding contact between the piston ring and the cylinder liner As a result, the frictional force between the piston ring and the cylinder liner is reduced, so that energy efficiency can be improved (low friction of the internal combustion engine) and a combination sliding member with excellent scuff resistance can be obtained. it can. Further, the combination sliding member of the present invention has a characteristic that seizure hardly occurs at the initial familiarization stage. Thus, the present invention specifies in detail the surface properties of the piston ring such as the surface roughness Rz, the initial wear height Rpk, the effective load roughness Rk, the oil sump depth Rvk, and the oil sump depth rate K. In addition, a structure having an oil sump and a surface roughness Rz of the cylinder liner are specified, thereby further reducing friction and scuffing resistance.

  According to the combination sliding member of the second aspect, it is possible to produce the piston ring provided in the combination sliding member of the present invention by performing each processing described above for the piston ring. Therefore, each of these processes is performed on the entire sliding surface of the piston ring, and is not performed partially. Therefore, an increase in cost can be suppressed, and the friction coefficient can be reduced to cope with a reduction in friction of the internal combustion engine. A combination sliding member that is low and excellent in scuff resistance can be provided.

  According to the combination sliding member of the third aspect, by adjusting the film thickness of the film formed on the piston ring, the surface shape can be easily adjusted by the lapping process which is one of the polishing processes. Therefore, it is possible to easily obtain a piston ring having the above surface properties.

  An embodiment applied to the combination sliding member of the present invention will be described with reference to FIGS. FIG. 1 shows a cross-sectional view orthogonal to the circumferential direction of the piston ring 10 and the cylinder liner 20 of one embodiment. FIG. 2 shows a cross-sectional view orthogonal to the circumferential direction of the piston ring 10 of another embodiment. FIG. 3 and FIG. 4 show diagrams for explaining a method of measuring the initial wear height Rpk, the effective load roughness Rk, and the oil sump depth Rvk.

  As shown in FIG. 1, the combination sliding member 30 of the present invention includes a piston ring 10 and a cylinder liner 20. The piston ring 10 has a sliding surface 11 having a surface roughness Rz of 0.3 to 2.5 μm, an initial wear height Rpk ≦ 0.15 μm, an effective load roughness Rk of 0.10 to 0.50 μm, and a sump depth of Rvk 0.20. It is -1.0 micrometer and the oil sump depth rate K (= Rvk / Rk) is 1.0-4.0. The cylinder liner 20 has a surface roughness Rz of 0.2 to 0.8 μm of the sliding surface 21. Thus, the combination sliding member 30 of the present invention specifies the surface properties of the surfaces 11 and 12 that slide on each other in the piston ring 10 and the cylinder liner 20.

  First, the piston ring 10 in the combination sliding member 30 will be described. The above surface properties of the sliding surface 11 of the piston ring 10 will be specifically described below.

  The surface roughness Rz is 0.3 to 2.5 μm, preferably more than 1.0 to 2.0 μm. If Rz is less than 0.3 μm, the lubricating oil cannot be sufficiently retained, and if it exceeds 2.5 μm, the other party's aggression increases. The surface roughness Rz indicates the maximum height of the contour curve, and is based on JIS standard B0601 (2001 revision), ISO standard 4287 (1997), and DIN standard 4768.

  The initial wear height Rpk is 0.15 μm or less, preferably 0.02 to 0.13 μm. When Rpk exceeds 0.15 μm, the bore (inner surface of the cylinder liner 20) becomes more aggressive, which is not preferable. The initial wear height Rpk is also referred to as the protruding peak height, and is based on JIS standard B0671-2 (2002), ISO standard 13565-2 (1996), and DIN standard 4776. The effective load roughness Rk and oil sump depth Rvk described below are also based on these standards. The measuring method of each value of initial wear height Rpk, effective load roughness Rk, and oil sump depth Rvk will be described later.

  The effective load roughness Rk is 0.10 to 0.50 μm, preferably 0.2 to 0.4 μm. If Rk is less than 0.10 μm, scuffing is easy, and if Rk exceeds 0.5 μm, the bore attack becomes high, which is not preferable. The effective load roughness Rk is also referred to as a level difference in the core portion.

  The oil sump depth Rvk is 0.20 to 1.0 μm, preferably 0.4 to 0.9 μm. When Rvk is less than 0.20 μm, a sufficient oil sump cannot be obtained and scuffing is likely. When Rvk exceeds 1.0 μm, the oil sump becomes large and oil consumption is affected. The oil sump depth Rvk is also referred to as a protruding valley depth.

  The sump depth ratio K (= Rvk / Rk) is 1.0 to 4.0. And preferably 1.5 to 3.5. The sump depth ratio K represents the ratio of the sump depth Rvk to the effective load roughness Rk, and the greater this value, the better the lubricity. When the oil sump depth ratio K is smaller than 1.0, the effect of the oil sump cannot be expected, and seizure tends to occur when the bore roughness becomes small. However, if the sump depth ratio K exceeds 4.0, the amount of lubricating oil consumed may increase.

  Here, a method for measuring the initial wear height Rpk, the effective load roughness Rk, and the oil sump depth Rvk according to JIS standard B0671-2 (2002), ISO standard 13565-2 (1996), and DIN standard 4776 will be described.

  As shown in FIG. 3, the initial wear height Rpk, the effective load roughness Rk, and the oil sump depth Rvk are plotted on the load curve 104 from the special roughness curve 103 of the target surface, and then the relative load on the load curve. A minimum slope line 105 is drawn that takes a width of 40% in the direction of the length ratio tp and passes through two points where the difference in height between the two ends is minimized. Next, the minimum slope line 105 and the relative load length ratio are drawn. It is calculated by obtaining the intersection points a and b with the tp 0% and 100% limit lines, and the intersection points c and d of the load curve 104 with the horizontal line passing through the intersection points a and b. The general procedure for obtaining the special roughness curve 103 is to first obtain the cross-sectional curve 106 of FIG. 4A based on JIS standard B0671-1, ISO standard 13565-1, and DIN standard 4776, and then the cross section thereof. A filter average line 107 of a phase compensation filtered waviness curve is obtained from the curve 106 using a Gaussian phase compensation filter or the like. Next, as shown in FIG. 4B, a valley below the filter average line is removed from the cross-sectional curve, and a valley-removed cross-sectional curve 108 is drawn. The valley removal sectional curve 108 is passed through a Gaussian phase compensation filter or the like to obtain a reference filter average line 109 shown in FIG. Finally, as shown in FIG. 4 (D), the reference filter average line 109 is subtracted from the cross-sectional curve 106 to draw a special roughness curve 110 shown in FIG. 4 (E). The special roughness curve 110 in FIG. 4E becomes the special roughness curve 103 in FIG.

  The initial wear height Rpk, effective load roughness Rk, and oil sump depth Rvk are obtained from FIG. 3 based on JIS standard B0671-2, ISO standard 13565-2, and DIN standard 4776. In FIG. 3, the initial wear height Rpk is the height of a right triangle whose base is ac and whose apex is on the limit line of the relative load length ratio tp0%, and the value of the initial wear height Rpk is the relative load length. It is calculated so as to be equal to the area of the portion surrounded by the rate tp0% limit line, the side ac, and the load curve. The effective load roughness Rk is a difference in height between c and d in FIG. 3 and is represented by a wear height until the target surface cannot be used. The oil sump depth Rvk is the height of a right triangle in FIG. 3 where bd is the base and the apex is on the limit line of the relative load length ratio tp 100%, and the value is the area of the right triangle. The rate tp is calculated to be equal to the area of the portion surrounded by the 100% limit line, the side bd, and the load curve.

  Further, in order to make the sliding surface 11 of the piston ring 10 have the above-mentioned surface properties, the piston ring 10 has a base material 13 made of spheroidal graphite cast iron as shown in FIG. The sliding surface 11 on which the hard film 12 is formed is shot blasted to remove graphite distributed on the sliding surface 11 and sink into the piston ring 10 (on the sliding surface 11). It is preferable that the hard coating 12 is formed and polished by physical vapor deposition after allowing the existing graphite to enter the piston ring 10). Rz, Rpk, Rk, Rvk, and K can be set to desired values by making the base material 13 of the piston ring 10 with high strength spheroidal graphite cast iron and performing such treatment.

  If the area ratio of the spherical graphite is less than 5%, the effect of oil accumulation cannot be obtained, and if it exceeds 20%, moisture adsorption and adsorption gas are easily generated by the graphite. In spheroidal graphite cast iron, the area ratio of spheroidal graphite is changed to 5 to 20% depending on the casting method (casting method, raw material shape) for forming the raw material. For example, a method of forming a material by forming a cylindrical material and processing it to form a ring material or a method of forming a large number of ring materials in a tree shape is desirable. In this case, the particle diameter of the spherical graphite is preferably in the range of 5 to 100 μm, and the average particle diameter is preferably 10 to 60 μm, depending on the casting method (casting method, material shape).

In shot blasting, the nozzle is usually adjusted so that it can be shot on the sliding surface 11 of the piston ring 10, and a grit such as steel or glass beads is compressed with compressed air or centrifugal force at a pressure of about 5 kg / cm ^2. Processing is performed by hitting against the sliding surface 11 of the ring 10. By performing shot blasting on the sliding surface 11 of the piston ring 10, when the piston ring 10 contains graphite, the graphite distributed on the sliding surface 11 can be removed. An oil sump can be formed.

  Examples of physical vapor deposition include ion plating, vacuum vapor deposition, molecular beam vapor deposition (MBE), ion beam vapor deposition, and sputtering. Arc ion plating, which is one of the ion plating methods, is preferable. Used.

  The material of the film 12 formed by the above-described physical vapor deposition method is not particularly limited, and Cr-N film, Cr-BN film, Cr-Ti-N film, Cr-Si-N film, Ti-N film, Any film that can be formed by physical vapor deposition, such as a Cr-Ti-BN film or a Cr-Si-BN film, may be used. These films are preferably formed from the past in order to improve the wear resistance, scuff resistance, etc. of the sliding surface 11 of the piston ring 10, but the surface of each layer should have the above-mentioned surface properties. Thus, the wear resistance and scuff resistance of the sliding surface 11 of the piston ring 10 can be further improved.

  As the polishing treatment, a conventionally known polishing treatment can be performed. For example, polishing by lapping processing, film polishing, or the like can be performed.

  Although the film thickness of the membrane | film | coat 12 formed in the sliding surface 11 of the piston ring 10 is not specifically limited, It is preferable that it is 5-70 micrometers. When the film thickness of the film 12 is within this range, it becomes easy to adjust the surface properties by lapping treatment which is one of polishing treatments. On the other hand, if the film thickness is less than 5 μm, it is difficult to adjust the surface properties by the lapping process, and if the film thickness exceeds 70 μm, the possibility of chipping due to the lapping process increases.

  By the treatment of the sliding surface 11 of the piston ring 10 as described above, it is easy to obtain the piston ring 10 having the above-mentioned surface properties.

  Here, a cast iron material is used as the material of the base material 13 of the piston ring 10, and specifically, spheroidal graphite cast iron is preferably used. Further, as shown in FIG. 2, a nitride layer 14 can be formed around the base material 13 of the piston ring 10. The nitride layer 14 is formed by diffusing nitrogen into the surface layer of the base material 13 by a known nitriding process, and is hard. By forming the nitride layer 14, the strength of the entire piston ring 10 can be improved, and the breakage resistance is improved. Further, by forming the nitride layer 14 on the upper surface 15 and the lower surface 16 orthogonal to the outer peripheral sliding surface 11 of the piston ring 10, it is possible to prevent the upper and lower surface wear on the piston ring 10 disposed on the piston trailer. In addition, the position where the nitride layer 14 is formed in the piston ring 10 is not limited to that illustrated in FIG. 2 and can be formed at any position as necessary.

  The piston ring 10 constituting the combination sliding member 30 of the present invention is mounted in a piston ring groove formed in a piston (not shown), and the inner peripheral surface of the cylinder liner 20 is moved by the vertical movement of the piston (same as reciprocal movement). A sliding member 30 that moves up and down while sliding. The piston ring 10 constituting the present invention may be a top ring, a second ring, an oil ring, or all of them.

  In addition, although the shape of the piston ring 10 is a rectangular ring in FIG. 1, it may be an outer peripheral shape such as a barrel face or a tapered face. The piston ring 10 may have a cross-sectional shape such as a half keystone ring, a full keystone ring, or a scraper ring. The oil ring may be an oil control ring with a window, a bevel oil control ring, a double bevel oil control ring or the like, or an oil ring with a coil expander other than those.

  Next, the cylinder liner 20 in the combination sliding member 30 will be described.

  The sliding surface 21 of the cylinder liner 20 has the surface properties described above, and will be specifically described below. The cylinder liner 20 has a surface roughness Rz of 0.2 to 0.8 μm, preferably 0.25 to 0.6 μm, and more preferably less than 0.3 to 0.5 μm. If Rz is less than 0.2 μm, the cylinder liner 20 may be easily seized, and if it exceeds 0.8 μm, it may not contribute to reduction of friction. The surface roughness Rz of the cylinder liner 20 is also the same standard as that in the piston ring 10 described above.

  The base material of the cylinder liner 20 is not particularly limited, and conventionally known materials such as cast iron, boron cast iron, steel, cast steel, and the like can be used.

  The processing performed to make the sliding surface 21 of the cylinder liner 20 have the above-mentioned surface properties is not particularly limited. For example, processing such as performing surface polishing sequentially after changing the material and fineness of the grinding wheel after grinding. By performing the above, the surface texture in the above-mentioned range can be obtained.

  According to the combined sliding member 30 comprising the piston ring 10 and the cylinder liner 20 of the present invention, the wear data based on the actual machine evaluation shows wear of about 1 to 3 μm in a 400-hour durability test, and has excellent wear resistance. Is. In particular, in the combination sliding member 30 of the present invention, the oil pool is formed not on the cylinder liner 20 but on the sliding surface 11 on the piston ring 10 side, so that the conformability at the initial stage of sliding can be improved. It is possible to prevent seizure of the piston ring 10 and the cylinder liner 20. In addition, by making the surface properties of the sliding surfaces 11 and 21 of the piston ring 10 and the cylinder liner 20 within the above-mentioned range, the frictional force with the cylinder liner 20 is reduced, which is suitable for low friction and has high scuff resistance. improves. Furthermore, in the combination sliding member 30 of the present invention, the oil plating is formed on the sliding surface 11 on the piston ring 10 side instead of the cylinder liner 20, so that the ion plating film 12 is hard and has excellent sliding characteristics. The sliding property is improved such that the initial conformability is improved, the friction is reduced, and the oil retaining property is excellent.

  The combination sliding member of the present invention will be specifically described with reference to examples and comparative examples. In the examples and comparative examples,% indicates mass%.

(Example)
(1) Formation of piston ring sliding surface (test piece fixed piece)
Spheroidal graphite cast iron as a base material for piston ring (C: 3.8%, Si: 2.8%, Mn: 0.7%, P: 0.2%, S: 0.05%, Cr: 0.3 %, Balance: iron and inevitable impurities). The graphite distribution on the surface of the spheroidal graphite cast iron was adjusted by removing the graphite on the cast iron surface by shot blasting and sinking it into the piston ring, thereby forming an oil pool on the sliding surface. Further, a Cr—N-based film was formed on the sliding surface of the piston ring by an ion plating method, and a Cr—N film oriented mainly in {200} was formed. By polishing by lapping treatment, Rz 0.3 to 2.5 μm, Rpk ≦ 0.15 μm, Rk 0.10 to 0.50 μm, Rvk 0.20 to 1.0 μm, oil sump depth ratio K (= Rvk / Rk) A piston ring test piece 51 having a surface texture of 1.0 to 4.0 was produced. The Cr—N film of the test piece 51 had a thickness of 50 μm and a hardness of 1400 Hv 0.05. The film of the test pieces 51 of Examples 1 to 11 was formed by changing the amount of graphite removed from the cast iron surface in the test piece 51 and adjusting the time of the final lapping process. Table 1 shows values of Rz, Rpk, Rk, Rvk, and K of the piston ring material (test piece) 51 of Examples 1 to 11. Moreover, it calculated | required in Table 1 and calculated | required the graphite area rate of the raw material formed on the same conditions as the test piece 51 of Examples 1-11. The area ratio of graphite was obtained by cutting the test piece material, polishing the cross section to make a mirror surface, enlarging the field of view to 50 times, and binarizing black and white with an image analyzer.

(2) Cylinder liner sliding surface formation (mating material rotating piece)
Boron cast iron (C: 3.35%, Si: 2.08%, Mn: 0.82%, P: 0.36%, S: 0.07%, B: 0.08) as a cylinder liner base material %, Balance: iron and inevitable impurities). After the sliding surface of the cylinder liner base material is ground, the surface of the cylinder liner is adjusted to a predetermined surface roughness Rz by sequentially changing the fineness of the grinding wheel to form the sliding surface of the cylinder liner. A material 52 was produced. The finished surface roughness was Rz 0.2 to 0.8 μm. Table 1 shows values of Rz of the cylinder liner materials (counter materials) 52 of Examples 1 to 11.

(Comparative example)
Spheroidal graphite cast iron as a base material for piston ring (C: 3.8%, Si: 2.8%, Mn: 0.7%, P: 0.2%, S: 0.05%, Cr: 0.3 %, Balance: iron and inevitable impurities). The cast iron surface was changed in surface roughness and graphite properties by polishing and shot blasting. Further, a Cr—N-based film was formed on the sliding surface of the piston ring by an ion plating method, and a Cr—N film mainly oriented in {200} was formed to a thickness of 50 μm. For finishing, a sliding surface of the piston ring material (test piece) of Comparative Examples 1 to 3 was formed by lapping treatment.

  Steel material (C: 0.85%, Cr: 17.7%, Mo: 1.1%, Mn: 0.35%, Si: 0.35, V: 0.12, balance of piston ring base material) : Iron and inevitable impurities). The surface of the steel material is polished, and a Cr—N-based film is formed on the sliding surface of the piston ring by an ion plating method, and a Cr—N film oriented mainly in {200} is formed to a thickness of 50 μm. did. The sliding surface of the piston ring material (test piece 51) of Comparative Example 4 was formed by performing a lapping process for finishing.

  Table 1 shows values of Rz, Rpk, Rk, Rvk, and K of the piston ring materials (test pieces 51) of Comparative Examples 1 to 4. Similarly to the examples, the graphite area ratio of the material formed under the same conditions as the test pieces 51 of Comparative Examples 1 to 3 was obtained and shown in Table 1. The area ratio of the graphite was obtained by cutting the test piece material, polishing the cross section to make a mirror surface, expanding the field of view to 50 times, and binarizing black and white with an image analyzer.

  Table 1 shows the Rz values of the cylinder liner materials (counter members 52) of Comparative Examples 1 to 4 in which the sliding surface of the cylinder liner was formed in the same manner as in the example.

（評価方法）
実施例１〜１１の組合せ摺動部材および比較例１〜４の組合せ摺動部材に対し、摩擦係数試験および耐スカッフ性試験を行った。

(Evaluation methods)
A friction coefficient test and a scuff resistance test were performed on the combination sliding members of Examples 1 to 11 and the combination sliding members of Comparative Examples 1 to 4.

  For the friction coefficient test and the scuff resistance test, an Amsler type abrasion tester 50 shown in FIG. 5 was used. The test piece 51 (dimensions 7 mm × 8 mm × 5 mm) having the surface roughness of Examples 1 to 11 and Comparative Examples 1 to 4 manufactured by the above method corresponding to the piston ring is used as a fixed piece, and the above corresponding to the cylinder liner. The counterpart material 52 (outer diameter 40 mm, inner diameter 16 mm, axial thickness 10 mm) having the surface roughness of Examples 1 to 11 and Comparative Examples 1 to 4 produced by the above method was used as a donut-shaped rotating piece.

  Lubricating oil 53 is stored in a container (not shown) of the testing machine 50, the mating material 52 is partially immersed in the lubricating oil 53 and rotated at a constant speed, the test piece 51 is brought into contact with the outer peripheral surface of the mating material 52, and the load is loaded. P was loaded. The load P applied to the test piece 51 was linearly increased at a rate of 49 N / min until scuffing occurred. The coefficient of friction between the test piece 51 and the mating member 52 was measured, and the limit load at which the test piece 51 generated scuffing was measured. The test conditions are as follows.

(Test conditions)
Test machine: Amsler type wear test machine Lubricating oil: No. 1 spindle oil equivalent applied Oil temperature: 80 ° C Peripheral speed: 1.0 m / s (478 rpm)
Table 1 shows the results of the friction coefficient test and the scuff resistance test. The friction coefficient index in Table 1 was obtained by calculating the friction coefficient of each combination with respect to Comparative Example 3 as a relative ratio, with the friction coefficient of the combination of Comparative Example 3 being 100. Therefore, it is shown that the smaller the friction coefficient index of each combination is, the smaller the friction and the higher the energy efficiency. On the other hand, when the coefficient of friction index is greater than 100, it indicates that the friction increases. Further, the scuff resistance index in Table 1 was obtained by calculating the scuffing limit load of each test piece 51 relative to Comparative Example 3 as a relative ratio with the scuffing limit load of the test piece 51 of Comparative Example 3 being 100. Therefore, as the scuff resistance index of each test piece 51 is larger than 100, the scuff limit load increases, indicating that the scuff resistance is excellent. On the other hand, when the scuff index is smaller than 100, it is easy to generate scuff.

(Evaluation results)
From Table 1 showing the results of the friction coefficient test and the scuff resistance test, it can be seen that Examples 1 to 11 are superior to Comparative Examples 1 to 4 in that the friction coefficient index is lower and the scuff resistance index is higher.

  Specifically, in Comparative Example 1 in which Rpk, Rk, and Rvk are deviated to the upper limit side, the scuff resistance index is slightly lowered, and since Rk is large, the frictional force is increased and the friction coefficient index is increased. . In Comparative Example 2 in which Rk and Rvk deviate to the lower limit side, the frictional force is small because Rk is small, but the scuff index is slightly lowered because Rvk is small. Comparative Example 3 shows a case where the sump depth ratio K is 1 or less, and since the value of Rk is larger than Rvk, the friction coefficient index is large, and the oil retention as Rvk is reduced, Small scuff resistance index.

  Thus, by making the surface properties of the piston ring and the cylinder liner within the scope of the present invention, it is possible to reduce the friction, improve the energy efficiency, and obtain a combined sliding member having excellent scuff resistance. It was.

It is sectional drawing orthogonal to the circumferential direction of the piston ring and cylinder liner of one Embodiment. It is sectional drawing orthogonal to the circumferential direction of the piston ring of other embodiment. It is a figure which shows the special roughness curve and load curve for demonstrating the measuring method of initial wear height Rpk, effective load roughness Rk, and oil sump depth Rvk. It is a figure which shows the procedure which calculates | requires the special roughness curve for demonstrating the measuring method of initial wear height Rpk, effective load roughness Rk, and oil sump depth Rvk. It is the schematic which shows the Amsler type | mold abrasion tester for performing the test which tests the effect of the combination sliding member by the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Piston ring 11 Sliding surface of piston ring 12 Film | membrane 13 Base material 14 Nitrided layer 15 Upper surface of piston ring 16 Lower surface of piston ring 20 Cylinder liner 21 Sliding surface of cylinder liner 30 Combination sliding member 50 Amsler type abrasion tester 51 Fixed piece 52 Rotating piece 53 Lubricating oil P Load load 103, 110 Special roughness curve 104 Load curve 105 Minimum slope straight line 106 Cross section curve 107 Filter average line 108 Valley removal cross section curve 109 Reference filter average line

Claims (3)

A combination sliding member comprising a piston ring and a cylinder liner,
Sliding surface roughness Rz 0.3 to 2.5 μm, initial wear height Rpk ≦ 0.15 μm, effective load roughness Rk 0.10 to 0.50 μm, oil sump depth Rvk 0.20 to 1.0 μm, oil A piston ring having a pool depth ratio K (= Rvk / Rk) of 1.0 to 4.0;
A combination sliding member comprising a cylinder liner having a sliding surface roughness Rz of 0.2 to 0.8 μm.   In the piston ring, the base material is made of spheroidal graphite cast iron, the area ratio of spheroidal graphite in the cross section of the base material is 5 to 20%, and the sliding surface on which the hard film is formed is shot blasted and the sliding surface 2. The combined sliding member according to claim 1, wherein the hard coating is formed by physical vapor deposition and polished after removing graphite distributed in the piston ring and sinking into the piston ring.   The combined sliding member according to claim 2, wherein the thickness of the coating is 5 to 70 μm.

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