JP6010278B2 - Combination of piston rings for diesel engines - Google Patents

Description

The present invention relates to a combination of piston rings for a diesel engine that is effective in reducing friction without increasing oil consumption .

  In recent years, demands for improving the fuel consumption of internal combustion engines for automobiles, including consideration due to environmental problems, have increased, and the same applies to diesel engines for internal combustion engines. In responding to this requirement, it is effective to reduce the friction at the contact point between the piston and the cylinder in the internal combustion engine. Here, the piston in the internal combustion engine is provided with a piston ring for realizing a smooth reciprocating motion in the cylinder bore and for sealing high-temperature combustion gas. The piston ring is composed of a compression ring that is mounted for preventing gas leakage and an oil ring that is mounted for scraping off excess oil adhering to the cylinder bore wall surface to perform oil control, which are usually used in combination. In addition, the piston ring is mounted with, for example, a compression ring such as a top ring, a second ring, and an oil ring in order from the piston top side close to the combustion chamber.

  In an internal combustion engine, in order to reduce the friction at the contact point between the piston and the cylinder, it can be realized by setting the pressure of the piston ring to the cylinder bore wall surface to be low and lowering the tension of the piston ring. This can be achieved by setting the axial width dimension and the radial thickness dimension of the piston ring small. However, although such means has been conventionally employed, there is a risk that the sealing performance of the piston ring will be lowered, and a gap may be formed between the piston ring and the cylinder bore wall surface. If there is a gap between the piston ring and the cylinder bore wall, the piston ring can withstand the explosion shock in the combustion chamber and seal high-temperature combustion gas stably for a long period of time, and oil can enter the combustion chamber. The function of sealing without it is insufficient, leading to a decrease in engine output and an increase in oil consumption. In particular, regarding a diesel engine for an internal combustion engine, with the recent increase in combustion pressure of the internal combustion engine due to measures for exhaust gas regulations, the load on the piston tends to increase, and a decrease in the sealing performance of the piston ring is not preferable.

  In order to avoid the above-mentioned problem, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2000-9225) discloses a second ring piston ring that can be used in a state where the pressure of the second land is lowered, and a high-pressure reciprocating mechanism, In particular, a piston ring suitable for mounting on a piston of an internal combustion engine is disclosed. Specifically, the piston ring disclosed in Patent Document 1 is “a top ring is a second ring that is spaced apart via a second land, and the second ring has a radial thickness and an axial width dimension. The second ring is smaller than the corresponding dimensions of the top ring, the tension of the second ring is smaller than the tension of the top ring, and the torsion of the inner peripheral part thereof rising from the bottom surface of the ring groove is applied to the second ring.

JP 2000-9225 A

However, the piston ring according to Patent Document 1 only discloses that the radial thickness and tension of the second ring are made smaller than the radial thickness and tension of the top ring with respect to the tension of the piston ring. That is, in the combination of piston rings according to Patent Document 1, the total tension of the combination of piston rings is reduced by reducing the radial thickness (a1 dimension) of the second ring to reduce the tension. Further, the piston ring combination according to Patent Document 1 has a large difference between the top ring tension (11.7 N) and the second ring tension (0.4 N) (the tension of the top ring is approximately 30 times the tension of the second ring). Has occurred. As described above, Patent Document 1 does not mention any tension reduction or oil control for the oil ring. Therefore, when the combination of the piston ring including the second ring and the top ring and the oil ring is used simply by using the technical idea of the piston ring according to Patent Document 1, the piston ring and the cylinder bore wall surface It is difficult to stabilize the friction reduction effect without increasing the oil consumption .

As described above, the present invention suppresses the variation in friction performance between the piston ring and the cylinder bore wall surface, and can stably obtain the effect of reducing friction without increasing oil consumption. The purpose of the present invention is to provide a combination of piston rings for diesel engines using a piston ring composed of an oil ring.

  Therefore, as a result of intensive studies, the present inventors have solved the above-mentioned problems by satisfying a predetermined condition for the tension of the piston ring. Hereinafter, the present invention will be described.

Combination of piston rings for a diesel engine according to the present invention: In a combination of piston rings composed of a top ring, a second ring and an oil ring used in a diesel engine, the oil ring includes an upper rail, a lower rail, and each of these rails. and a web connecting the outer circumferential sliding surface of the upper rail and the lower rail, and a layer formed by a layer with PVD process formed by processing gas nitriding in this order, and, It is a step land shape in which the corner on the side facing the web in a symmetrical position across the web is cut out in a step shape, and the tension (N) of the top ring is A, and the tension of the second ring ( When N) is B, the tension (N) of the oil ring is C, and the cylinder bore diameter (mm) is D, the following formula 1 A combination of piston rings for a diesel engine, which satisfies the conditions of formulas (1) to (3).

  In the combination of the piston ring for a diesel engine according to the present invention, the ratio of the tension ratio with respect to the cylinder bore diameter of the oil ring with respect to the tension ratio with respect to the cylinder bore diameter of the top ring is that the tension (N) of the top ring is A. When the ring tension (N) is C and the cylinder bore diameter (mm) is D, it is preferable to satisfy the condition of the formula (4) shown in the following formula 2.

In the combination of a piston ring for a diesel engine according to the present invention, the top ring preferably includes at least a layer formed by gas nitriding treatment and / or a layer formed by PVD treatment on the outer peripheral sliding surface.

The combination of a piston ring for a diesel engine according to the present invention is preferably the outer circumferential sliding surface of the top ring is barrel face shape.

The combination of the piston ring for a diesel engine according to the present invention can reduce friction without increasing the oil consumption by setting the tension ratio to the cylinder bore diameter of the piston ring mounted on the piston as the condition defined in the present invention. The effect can be obtained stably.

It is the schematic sectional drawing cut | disconnected and shown in the cylinder axial direction, in order to demonstrate the relationship between the piston and cylinder which mounted the piston ring of this invention. It is the schematic sectional drawing which cut | disconnected and illustrated in the axial direction in order to demonstrate the shape of the outer periphery sliding surface of the oil ring of this invention.

  The present invention will be described in more detail below with reference to the drawings showing preferred embodiments of a combination of piston rings for a diesel engine according to the present invention.

  FIG. 1 is a schematic cross-sectional view cut along the cylinder axial direction in order to explain the relationship between a piston and a cylinder equipped with the piston ring of the present invention. As shown in FIG. 1, the piston 10 is provided with a top ring 2, a second ring 3, and an oil ring 4, which are the piston rings 1, in order from the top of the piston in the piston ring grooves 12 to 14 provided in the piston 10. In this state, the cylinder 20 reciprocates in the cylinder bore 22 provided in the cylinder 20. At this time, the piston ring 1 is pressed by its own tension against the cylinder bore wall surface 21 with the top ring 2 and the second ring 3, which are so-called compression rings, mounted in the piston ring grooves 12 and 13, respectively. As a result, the gap between the piston 10 and the cylinder bore wall surface 21 is filled to seal the combustion gas. The piston ring 1 is pressed against the cylinder bore wall surface 21 in a state where the oil ring 4 is mounted in the piston ring groove 14, thereby scraping off excess oil on the cylinder bore wall surface 21 and an oil film on the cylinder bore wall surface 21. Moderately control the thickness. As shown in FIG. 1, the oil ring 4 of the present invention employs what is called a so-called two-piece type oil ring composed of a coil expander 5 and an oil ring main body 6.

Combination of piston rings for diesel engines according to the present invention: The combination of piston rings for diesel engines according to the present invention comprises a top ring 2, a second ring 3, and an oil ring 4, as shown in FIG. In the combination of the piston rings according to the present invention, the oil ring includes an upper rail, a lower rail, and a web connecting these rails. The outer peripheral sliding surface of the upper rail and the lower rail, a layer formed by processing gas nitriding (hereinafter referred to as "gas nitrided layer") and PVD treated layer formed (hereinafter , Referred to as “PVD treatment layer” in this order , and in a step land shape in which corners on the side facing the web in a symmetrical position with the web in between are cut out in a step shape. In the oil ring, the tension (N) of the top ring 2 is A, the tension (N) of the second ring is B, the tension (N) of the oil ring 4 is C, and the diameter of the cylinder bore 22 When (mm) is set to D, each of the conditions of the formulas (1) to (3) shown in the following formula 1 is satisfied.

The outer peripheral sliding surface of the oil ring 4 of the present invention has a step land shape as shown in FIG. 1, so that an effect of scraping off excess oil on the cylinder bore wall surface 21 by the oil ring 4 can be further obtained. . That is, according to the oil ring 4 of the present invention, since the outer peripheral sliding surface has a step land shape, it is difficult for oil to rise, and it is possible to reduce oil consumption and friction.

FIG. 2 is a schematic cross-sectional view illustrated by cutting in the axial direction to explain the shape of the outer peripheral sliding surface of the oil ring of the present invention. As shown in FIG. 2, the oil ring main body 6 in the oil ring 4 of the present invention includes an upper rail 6a and a lower rail 6b that constitute an upper portion and a lower portion of the oil ring main body, and a web connected to these rails. 6c. Stepped notches 6a 'and 6b' are formed on the outer peripheral sliding surfaces of the upper rail 6a and the lower rail 6b. Here, in FIG. 2, the step 6a ′ provided on the upper rail 6a and the step 6b ′ provided on the lower rail 6b are provided on the web 6c on the outer peripheral sliding surface of the upper rail 6a and the lower rail 6b. It is formed in the corner on the facing side and at a symmetrical position with the web 6c interposed therebetween. In the oil ring 4 of the present invention, by providing the steps 6a ′ and 6b ′ at the locations shown in FIG. 2, the oil control function by the oil ring 4 can be further exerted and the friction can be reduced. .

Note that the steps 6a ′ and 6b ′ provided on the outer peripheral sliding surface of the oil ring 4 take into account the axial width of the contact surface of the upper ring 6a and the lower rail 6b of the oil ring body 6 with respect to the cylinder bore wall surface 21. The upper rail 6a and the lower rail 6b can be formed by grinding using, for example, a polishing member or a grindstone. Therefore, the oil ring main body 6 of the present invention can form the outer peripheral shape of the rails 6a and 6b with high dimensional accuracy, although it is a simple method that does not require special equipment or special skills for its formation. .

Further, in the combination of the piston ring for a diesel engine according to the present invention, the upper rail 6a and the lower rail 6b of the oil ring 4 have a gas nitriding treatment layer and a PVD treatment layer in this order at least on the outer peripheral sliding surface thereof. It is. The oil ring 4 according to the present invention has the gas nitriding layer and the PVD layer on at least the outer peripheral sliding surface in this order, thereby improving the durability and extending the life of the internal combustion engine. In addition, since the oil ring 4 in the present invention is exposed to a severe environment with a high heat load, the gas nitriding treatment layer and the PVD treatment layer are not only sliding surfaces with the cylinder bore wall surface of the oil ring 4, You may form in the whole surface including the upper surface and lower surface which contact a piston ring groove | channel.

Furthermore, the combination of the piston ring for a diesel engine according to the present invention is based on the conditions of the formula (1) and the formula (2) shown in the above formula 1 with respect to the tension ratio of the top ring 2 or the oil ring 4 to the diameter of the cylinder bore 22. By satisfying the above, it is possible to effectively reduce the friction between the piston ring 1 and the cylinder bore wall surface 21 while maintaining the sealing performance of the piston 10 with respect to the cylinder bore wall surface 21 to prevent an increase in oil consumption . be able to. In the formula (1), when A / D exceeds 0.25, the pressing force of the top ring 2 against the cylinder bore wall surface 21 becomes too high, and the friction between the piston ring 1 and the cylinder bore wall surface 21 is reduced. I can't. In the formula (2), when C / D is less than 0.10, the pressing force of the oil ring 4 against the cylinder bore wall surface 21 becomes too low, and excess oil on the cylinder bore wall surface 21 is removed from the oil ring 4. Makes it difficult to scrape off. Further, in the formula (2), when C / D exceeds 0.36, the pressing force against the cylinder bore wall surface 21 of the oil ring 4 becomes too high, and the thickness of the oil film on the cylinder bore wall surface 21 can be controlled. It becomes difficult to reduce the friction.

In addition, the combination of the piston ring for a diesel engine according to the present invention is based on the condition of the formula (3) shown in the above equation 1 as the total tension ratio with respect to the diameter of the cylinder bore 22 of the top ring 2, the second ring 3 and the oil ring 4 to be used. When satisfied, the tension of each ring can be set to a preferable balance distribution as a combination of the piston rings 1. As a result, according to the piston ring combination according to the present invention, it is possible to more effectively reduce the friction between the piston ring 1 and the cylinder bore wall surface 21 without increasing the oil consumption . In the formula (3), when (A + B + C) / D is less than 0.2, the tension of the top ring 2 and / or the second ring 3 is too low, so that the sealing performance against the cylinder bore wall surface 21 by the piston ring 1 is achieved. It will be difficult to maintain sufficient. Further, in the formula (3), when (A + B + C) / D exceeds 0.9, the tension of the top ring 2 and / or the second ring 3 is too high, so that the space between the piston ring 1 and the cylinder bore wall surface 21 It is impossible to reduce the friction.

  In the combination of the piston ring for a diesel engine according to the present invention, the ratio of the tension ratio of the oil ring 4 to the cylinder bore 22 to the tension ratio of the top ring 2 to the cylinder bore 22 is the tension (N) of the top ring 2. When A is set, A is the tension (N) of the oil ring 4 is C, and the diameter (mm) of the cylinder bore 22 is D, it is preferable to satisfy the condition of the following expression (4).

The combination of the piston ring for a diesel engine according to the present invention shows the ratio of the “tension ratio of the oil ring 4 to the diameter of the cylinder bore 22” to the “tension ratio of the top ring 2 to the diameter of the cylinder bore 22”. By satisfying the condition of Expression (4), the stability of the effect relating to the reduction of friction between the piston ring 1 and the cylinder bore wall surface 21 is increased without increasing the oil consumption . In the formula (4), when (C / D) / (A / D) is less than 0.8, the “cylinder bore 22 of the oil ring 4” with respect to the “tension ratio of the top ring 2 to the diameter of the cylinder bore 22”. Since the ratio of “tension ratio to diameter” is too low, the function of scraping off excess oil on the cylinder bore wall surface 21 cannot be stably obtained, and stability of the effect of preventing an increase in oil consumption is lacking. In the formula (4), when (C / D) / (A / D) exceeds 1.6, “the cylinder bore 22 of the oil ring 4” with respect to the “tension ratio of the top ring 2 to the diameter of the cylinder bore 22”. Since the ratio of the “tension ratio to the diameter” is too high, the oil scraping performance is improved, but the friction between the piston ring 1 and the cylinder bore wall surface 21 is increased.

In the combination of the piston ring for a diesel engine according to the present invention, the top ring 2 preferably includes a gas nitriding layer and / or a PVD layer on at least the outer peripheral sliding surface.

In the combination of the piston ring for a diesel engine according to the present invention, the top ring 2 is provided with a gas nitriding treatment layer and / or a PVD treatment layer on at least the outer peripheral sliding surface, thereby improving the durability of the piston ring 1 and improving the internal combustion. The engine life can be extended. Since the top ring 2 in the present invention is exposed to a severe environment with a high heat load, the surface of the gas nitriding layer is further provided with a surface treatment layer obtained by using a physical vapor deposition (PVD) technique. From the viewpoint of sex, it is more preferable. The gas nitriding treatment layer and / or the PVD treatment layer may be formed not only on the sliding surface with the cylinder bore wall surface of the top ring 2 but also on the entire surface including the upper surface and the lower surface in contact with the piston ring groove. Although the second ring 3 is not particularly mentioned, the second ring 3 is also provided with a gas nitriding layer and / or a PVD processing layer on at least the outer peripheral sliding surface like the top ring 2. Further, it is possible to further extend the life of the internal combustion engine.

Incidentally, the piston ring 1 of the present invention can also be formed with a diamond-like carbon layer (hereinafter referred to as “DLC layer”) as a wear-resistant layer having wear resistance on the upper and lower surfaces thereof. The DLC layer as possible out be provided on the outermost layer of the upper and lower surfaces that form a gas nitrided layer or a PVD process layer of the piston ring described above. This DLC layer is known as a low friction material having a low friction coefficient. By providing the DLC layer on the surfaces of the upper surface and the lower surface, the wear resistance can be remarkably improved. The piston ring 1 of the present invention may be provided with a DLC layer on the outer peripheral sliding surface of the ring as a wear-resistant layer in order to further improve the durability.

The combination of a piston ring for a diesel engine according to the present invention is preferably the outer circumferential sliding surface of the top ring 2 is barrel face shape.

The outer peripheral sliding surface of the top ring 2 of the present invention has a barrel face shape as shown in FIG. 1, so that the pressing force of the top ring 2 against the cylinder bore wall surface 21 can be uniformly applied in the circumferential direction. Become. As a result, according to the top ring 2 of the present invention, the sealing performance between the top ring 2 and the cylinder bore wall surface 21 can be stably maintained, and oil consumption and friction can be reduced. Is preferred .

  In the combination of piston rings for a diesel engine according to the present invention, the top ring 2 and / or the second ring 3 may have a keystone shape or a half keystone shape in the axial cross section. The top ring 2 and / or the second ring 3 which is the piston ring 1 of the present invention has a shape in which the upper and lower surfaces or the upper surface of the piston ring is inclined such that the shape in the axial cross section is a keystone shape or a half keystone shape. In this case, due to the movement of the piston ring in the radial direction in the piston ring groove, the upper surface or the lower surface provided with the inclination of the piston ring hits sludge or carbon deposited in the groove with high surface pressure, It can be easily crushed or scraped off. As a result, by adopting a piston ring with a keystone shape or a half keystone shape in the axial cross section, sludge accumulated in the piston ring groove is fixed or stuck to the ring, preventing the ring from moving. Can do. As described above, the top ring 2 and / or the second ring 3 according to the present invention has a keystone shape or a half keystone shape in the axial cross section, thereby improving the sealing performance of the upper and lower surfaces of the ring and ensuring combustion gas. Since it can seal and it will contribute to exhaust gas regulations etc., it is preferable.

  Here, for reference, materials and compositions suitably used for the piston rings of the top ring, the second ring, and the oil ring, which are used in the combination of the piston ring for diesel according to the present invention, are illustrated below. The material of the oil ring body of the present invention is not limited to these materials.

  First, 13Cr steel can be used for the piston ring for the top ring of the present invention. This 13Cr steel is composed of carbon 0.6 to 0.7 mass%, silicon 0.25 to 0.5 mass%, manganese 0.20 to 0.50 mass%, chromium 13.0 to 14.0 mass%, molybdenum A composition having a composition of 0.2 to 0.4% by mass, phosphorus of 0.03% by mass or less, sulfur of 0.03% by mass or less, the remaining iron and inevitable impurities.

  Moreover, 17Cr steel can be used for the piston ring for top rings of this invention. This 17Cr steel is composed of carbon 0.80 to 0.95 mass%, silicon 0.35 to 0.5 mass%, manganese 0.25 to 0.40 mass%, chromium 17.0 to 18.0 mass%, molybdenum The composition of 1.00-1.25 mass%, phosphorus 0.04 mass% or less, sulfur 0.04 mass% or less, vanadium 0.08-0.15 mass%, the balance iron and inevitable impurities.

  Next, a cast iron material (spheroidal graphite cast iron) can be used for the piston ring for the second ring of the present invention. This cast iron material is carbon 3.30 to 4.00 mass%, silicon 2.20 to 3.50 mass%, manganese 1.0 mass% or less, phosphorus 0.3 mass% or less, sulfur 0.05 mass% or less. , 0.5 mass% or less of chromium, 0.5 mass% or less of copper, the balance iron and inevitable impurities.

  The second ring piston ring of the present invention can be made of 8Cr steel. This 8Cr steel is composed of carbon 0.6 to 0.8% by mass, silicon 0.15 to 0.35% by mass, manganese 0.20 to 0.40% by mass, chromium 7.00 to 9.00% by mass, phosphorus 0.04% by mass or less, sulfur 0.03% by mass or less, the balance iron and inevitable impurities.

  The second ring piston ring of the present invention can use 10Cr steel. This 10Cr steel is composed of carbon 0.4 to 0.6 mass%, silicon 0.1 to 0.3 mass%, manganese 0.20 to 0.40 mass%, chromium 9.0 to 11.0 mass%, phosphorus 0.04% by mass or less, sulfur 0.03% by mass or less, the balance iron and inevitable impurities.

  Next, 13Cr steel can be used for the oil ring body of the present invention. This 13Cr steel is composed of carbon 0.6 to 0.7 mass%, silicon 0.25 to 0.5 mass%, manganese 0.20 to 0.50 mass%, chromium 13.0 to 14.0 mass%, molybdenum A composition having a composition of 0.2 to 0.4% by mass, phosphorus of 0.03% by mass or less, sulfur of 0.03% by mass or less, the remaining iron and inevitable impurities.

  Moreover, 17Cr steel can be used for the oil ring main body of this invention. This 17Cr steel is composed of carbon 0.80 to 0.95 mass%, silicon 0.35 to 0.5 mass%, manganese 0.25 to 0.40 mass%, chromium 17.0 to 18.0 mass%, molybdenum 1.00 to 1.25% by mass, vanadium 0.08 to 0.15% by mass, phosphorus 0.04% by mass or less, sulfur 0.04% by mass or less, balance iron and inevitable impurities.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. Note that the present invention is not limited to the following examples.

  In Example 1, an actual machine test of a 6-cylinder diesel engine with a displacement of 10,000 cc and a cylinder bore diameter of 125 mm was conducted, and it was confirmed how the difference in tension ratio with respect to the cylinder bore diameter of the piston ring used had an effect on oil consumption. Went. The engine operating conditions were 100 hours at full load (WOT). And the piston ring to be used was made into the combination which consists of a top ring, a second ring, and an oil ring. At this time, the top ring made of 17Cr steel having an axial height of 3.5 mm and a radial thickness of 4.6 mm is subjected to gas nitriding treatment, and the outer peripheral sliding surface is further subjected to PVD treatment (Cr-N series). ) Was used. The second ring was made of 10Cr steel, and had an axial height of 2.5 mm and a radial thickness of 4.5 mm, which was gas-nitrided. The oil ring was made of 13Cr steel, and had an axial height of 3.5 mm and a radial thickness of 2.35 mm and was subjected to gas nitriding treatment. In addition, about the said oil ring, the outer peripheral sliding surface used the step land shape.

  Here, the 17Cr steel constituting the top ring is carbon 0.90 mass%, silicon 0.40 mass%, manganese 0.30 mass%, chromium 17.5 mass%, molybdenum 1.10 mass%, vanadium 0.8. This corresponds to a JIS standard SUS440B material having a composition of 12 mass%, phosphorus 0.02 mass%, sulfur 0.01 mass%, the remaining iron and inevitable impurities.

  The 10Cr steel constituting the second ring is carbon 0.50% by mass, silicon 0.20% by mass, manganese 0.30% by mass, chromium 10.2% by mass, phosphorus 0.03% by mass, sulfur 0.02%. It has a composition of mass%, the balance iron and inevitable impurities.

  The 13Cr steel constituting the oil ring main body is 0.65% by mass of carbon, 0.38% by mass of silicon, 0.35% by mass of manganese, 13.50% by mass of chromium, 0.3% by mass of molybdenum, 0.3% by mass of phosphorus. This corresponds to JIS standard SUS410 material having a composition of 01 mass%, sulfur 0.01 mass%, the balance iron and inevitable impurities.

  In the first embodiment, the combinations of the piston rings are different from each other in the tension ratio of the top ring, the second ring, and the oil ring to the cylinder bore diameter. Specifically, in Example 1, the tension and cylinder bore diameter of each ring of the top ring, the second ring, and the oil ring were set to the conditions shown in Table 1 below. From Table 1, the combination of the piston rings of Example 1 has the following conditions.

Top ring tension A: 31N
Second ring tension B: 29N
Oil ring tension C: 44N
Cylinder bore diameter D: 125.0mm

  In the first embodiment, by setting the combination of the piston rings to the above conditions, the tension ratio of the top ring or the oil ring to the cylinder bore diameter is set such that the tension (N) of the top ring is A and the tension of the oil ring ( When N) is C and the cylinder bore diameter (mm) is D, A / D is 0.248 and C / D is 0.352. That is, Example 1 satisfies the conditions of the present invention (Equations (1) and (2) of Formula 1).

  In Example 1, the combination of the piston rings is set to the above conditions, so that the tension (N) of the top ring is A, the tension (N) of the second ring is B, and the tension (N) of the oil ring is When C is C and the cylinder bore diameter (mm) is D, the total tension ratio ((A + B + C) / D) of the tension ratio with respect to the cylinder bore diameter of each ring of the top ring, the second ring, and the oil ring is 0. 832. That is, Example 1 satisfies the conditions of the present invention (Equation (3) in Formula 1).

  In the first embodiment, the piston ring combination is set to the above conditions so that the top ring tension (N) is A, the oil ring tension (N) is C, and the cylinder bore diameter (mm) is D. In this case, (C / D) / (A / D) is 1.419. That is, Example 1 satisfies the conditions of the present invention (Equation (4) in Formula 2).

  From the above, Example 1 satisfies all of the conditions of the present invention (Equations (1) to (3) of Equation 1 and Equation (4) of Equation 2). Based on the above, the results of the oil consumption confirmation test under the conditions of Example 1 are shown in Table 1 together with the conditions. Table 1 shows combinations of piston rings that do not satisfy the conditions shown in Equations (2) and (3) of Equation 1 and Equation (4) of Equation 2 among the conditions of the present invention (Comparative Example 1 shown below). The oil consumption obtained by conducting an actual machine test using is used as a reference “1” and is expressed as a relative ratio. As a result, the oil consumption ratio of Example 1 was 1.

  In Example 2, an actual machine test of a 4-cylinder diesel engine with a displacement of 2500 cc and a cylinder bore diameter of 94 mm was conducted, and it was confirmed how the difference in tension ratio with respect to the cylinder bore diameter of the piston ring used had an effect on oil consumption. Went. The engine operating conditions were 100 hours at full load (WOT). And the piston ring to be used was made into the combination which consists of a top ring, a second ring, and an oil ring. At this time, the top ring made of 17Cr steel having an axial height of 2.0 mm and a radial thickness of 3.5 mm is subjected to gas nitriding treatment, and the outer peripheral sliding surface is subjected to PVD treatment (Cr-N series). ) Was used. The second ring is made of 10Cr steel, and has an axial height of 1.5 mm and a radial thickness of 3.1 mm, which has been subjected to gas nitriding treatment. The oil ring is made of 13Cr steel, and has an axial height of 2.0 mm and a radial thickness of 2.0 mm, which has been subjected to gas nitriding treatment, and the outer peripheral sliding surface has been subjected to PVD treatment (Cr-N system). A thing was used. In addition, about the said oil ring, the outer peripheral sliding surface used the step land shape.

  Here, the 17Cr steel constituting the top ring is carbon 0.90 mass%, silicon 0.40 mass%, manganese 0.30 mass%, chromium 17.5 mass%, molybdenum 1.10 mass%, vanadium 0.8. This corresponds to a JIS standard SUS440B material having a composition of 12 mass%, phosphorus 0.02 mass%, sulfur 0.01 mass%, the remaining iron and inevitable impurities.

  The 10Cr steel constituting the second ring is carbon 0.50% by mass, silicon 0.20% by mass, manganese 0.30% by mass, chromium 10.2% by mass, phosphorus 0.03% by mass, sulfur 0.02%. It has a composition of mass%, the balance iron and inevitable impurities.

  The 13Cr steel constituting the oil ring main body is 0.65% by mass of carbon, 0.38% by mass of silicon, 0.35% by mass of manganese, 13.50% by mass of chromium, 0.3% by mass of molybdenum, 0.3% by mass of phosphorus. This corresponds to JIS standard SUS410 material having a composition of 01 mass%, sulfur 0.01 mass%, the balance iron and inevitable impurities.

  In Example 2, combinations of piston rings that differ in tension ratio with respect to the cylinder bore diameter of the top ring, the second ring, and the oil ring used were used. Specifically, in Example 2, the tension and the cylinder bore diameter of each ring of the top ring, the second ring, and the oil ring were set to the conditions shown in Table 1 below. From Table 1, the combination of the piston rings of Example 2 has the following conditions.

Top ring tension A: 16N
Second ring tension B: 10N
Oil ring tension C: 22N
Cylinder bore diameter D: 94.0 mm

  In the second embodiment, by setting the combination of the piston rings to the above conditions, the tension ratio of the top ring or the oil ring to the cylinder bore diameter is set such that the tension (N) of the top ring is A and the tension of the oil ring ( When N) is C and the cylinder bore diameter (mm) is D, A / D is 0.170 and C / D is 0.234. That is, Example 2 satisfies the conditions of the present invention (Equations (1) and (2) of Formula 1).

  In Example 2, the combination of the piston rings is set to the above conditions, so that the tension (N) of the top ring is A, the tension (N) of the second ring is B, and the tension (N) of the oil ring is When C is C and the cylinder bore diameter (mm) is D, the total tension ratio ((A + B + C) / D) of the tension ratio with respect to the cylinder bore diameter of each ring of the top ring, the second ring, and the oil ring is 0. 511. That is, Example 2 satisfies the conditions of the present invention (Equation (3) in Formula 1).

  In the second embodiment, the piston ring combination is set to the above conditions, so that the top ring tension (N) is A, the oil ring tension (N) is C, and the cylinder bore diameter (mm) is D. In this case, (C / D) / (A / D) is 1.375. That is, Example 2 satisfies the conditions of the present invention (Equation (4) in Formula 2).

  From the above, Example 2 satisfies all the conditions of the present invention (Equations (1) to (3) of Equation 1 and Equation (4) of Equation 2). Based on the above, the results of the oil consumption confirmation test under the conditions of Example 2 are shown in Table 1 together with the conditions. Table 1 shows an actual machine test using a combination of piston rings (Comparative Example 2 shown below) that does not satisfy the conditions shown in Formula (2) of Formula 1 and Formula (4) of Formula 2 among the conditions of the present invention. The amount of oil consumption obtained by performing the above is set as a reference “1”, and is expressed as a relative ratio thereto. As a result, the oil consumption ratio of Example 2 was 1.

  In Example 3, an actual machine test of a 4-cylinder diesel engine having a displacement of 2500 cc and a cylinder bore diameter of 95.0 mm was conducted, and how the difference in tension ratio with respect to the cylinder bore diameter of the piston ring used affects oil consumption. We confirmed about. The engine operating conditions were 100 hours at full load (WOT). And the piston ring to be used was made into the combination which consists of a top ring, a second ring, and an oil ring. At this time, the top ring is made of 13Cr steel having an axial height of 2.0 mm and a radial thickness of 3.5 mm, and subjected to gas nitriding treatment, and the outer peripheral sliding surface is subjected to PVD treatment (Cr-N series). ) Was used. The second ring is made of 10Cr steel and has an axial height of 1.5 mm and a radial thickness of 3.5 mm. The oil ring is made of 13Cr steel, and has an axial height of 2.0 mm and a radial thickness of 2.0 mm that has been subjected to gas nitriding treatment. In addition, about the said oil ring, the outer peripheral sliding surface used the step land shape.

  Here, the 13Cr steel constituting the top ring is carbon 0.65% by mass, silicon 0.38% by mass, manganese 0.35% by mass, chromium 13.50% by mass, molybdenum 0.3% by mass, phosphorus 0. This corresponds to JIS standard SUS410 material having a composition of 01 mass%, sulfur 0.01 mass%, the balance iron and inevitable impurities.

  The 10Cr steel constituting the second ring is carbon 0.50% by mass, silicon 0.20% by mass, manganese 0.30% by mass, chromium 10.2% by mass, phosphorus 0.03% by mass, sulfur 0.02%. It has a composition of mass%, the balance iron and inevitable impurities.

  The 13Cr steel constituting the oil ring main body is 0.65% by mass of carbon, 0.38% by mass of silicon, 0.35% by mass of manganese, 13.50% by mass of chromium, 0.3% by mass of molybdenum, 0.3% by mass of phosphorus. This corresponds to JIS standard SUS410 material having a composition of 01 mass%, sulfur 0.01 mass%, the balance iron and inevitable impurities.

  In Example 3, combinations of different piston rings were used in which the tension ratios of the top ring, the second ring, and the oil ring used to the cylinder bore diameter were different. Specifically, in Example 3, the tension and cylinder bore diameter of each ring of the top ring, the second ring, and the oil ring were set to the conditions shown in Table 1 below. From Table 1, the combination of the piston rings of Example 3 has the following conditions.

Top ring tension A: 14N
Second ring tension B: 8N
Oil ring tension C: 12N
Cylinder bore diameter D: 95.0mm

  In the third embodiment, by setting the combination of the piston rings to the above conditions, the tension ratio of the top ring or the oil ring to the cylinder bore diameter is set such that the tension (N) of the top ring is A, and the tension of the oil ring ( When N) is C and the cylinder bore diameter (mm) is D, A / D is 0.147 and C / D is 0.126. That is, Example 3 satisfies the conditions of the present invention (Equations (1) and (2) in Formula 1).

  In Example 3, the combination of the piston rings is set to the above conditions, so that the tension (N) of the top ring is A, the tension (N) of the second ring is B, and the tension (N) of the oil ring is When C is C and the cylinder bore diameter (mm) is D, the total tension ratio ((A + B + C) / D) of the tension ratio with respect to the cylinder bore diameter of each ring of the top ring, the second ring, and the oil ring is 0. 356. That is, Example 3 satisfies the conditions of the present invention (Equation (3) in Formula 1).

  In the third embodiment, the piston ring combination is set to the above conditions so that the top ring tension (N) is A, the oil ring tension (N) is C, and the cylinder bore diameter (mm) is D. In this case, (C / D) / (A / D) is 0.857. That is, Example 3 satisfies the conditions of the present invention (Equation (4) in Formula 2).

  From the above, Example 3 satisfies all of the conditions of the present invention (Equations (1) to (3) of Equation 1 and Equation (4) of Equation 2). Based on the above, the results of the oil consumption confirmation test under the conditions of Example 3 are shown in Table 1 together with the conditions. Table 1 shows the oil consumption obtained by conducting an actual machine test using a combination of piston rings (Comparative Example 3 shown below) that does not satisfy the condition shown in Equation (4) of Formula 2 among the conditions of the present invention. The quantity is set as a reference “1” and is displayed as a relative ratio. As a result, the oil consumption ratio of Example 3 was 1.

Comparative example

[Comparative Example 1]
Comparative Example 1 is used for comparison with Example 1. In Comparative Example 1, the same engine as in Example 1 was used, and the engine was driven under the same driving conditions as in Example 1 to confirm the oil consumption. And the piston ring of the comparative example 1 employs a combination of a top ring, a second ring, and an oil ring as in the case of the embodiment 1, and the outer peripheral sliding surface of the oil ring has a step land shape. Except for the above, all the rings having the same cross-sectional shape and material as the piston ring of Example 1 were used.

  In Comparative Example 1, as a combination of piston rings, conventional equivalents in which the tension ratios of the top ring, the second ring, and the oil ring used to the cylinder bore diameter are different from each other were used. Specifically, in Comparative Example 1, the tension of each ring of the top ring, the second ring, and the oil ring, and the cylinder bore diameter were set to the conditions shown in Table 1 below. From Table 1, the combination of the piston rings of Comparative Example 1 satisfies the following conditions.

Top ring tension A: 31N
Second ring tension B: 29N
Oil ring tension C: 88N
Cylinder bore diameter D: 125.0mm

  In Comparative Example 1, by setting the combination of piston rings to the above conditions, the tension ratio of the top ring or the oil ring to the cylinder bore diameter is set such that the tension (N) of the top ring is A and the tension of the oil ring ( When N) is C and the cylinder bore diameter (mm) is D, A / D is 0.248 and C / D is 0.704. That is, Comparative Example 1 does not satisfy the condition shown in Equation (2) of Formula 1 among the conditions of the present invention.

  In Comparative Example 1, the combination of the piston rings is set to the above conditions, so that the tension (N) of the top ring is A, the tension (N) of the second ring is B, and the tension (N) of the oil ring is When C is C and the cylinder bore diameter (mm) is D, the total tension ratio ((A + B + C) / D) of the tension ratio to the cylinder bore diameter of each ring of the top ring, the second ring, and the oil ring is 1. 184. That is, Comparative Example 1 does not satisfy the condition shown in Equation 1 (3) among the conditions of the present invention.

  In Comparative Example 1, the combination of the piston rings is set to the above conditions, so that the tension (N) of the top ring is A, the tension (N) of the oil ring is C, and the cylinder bore diameter (mm) is D. In this case, (C / D) / (A / D) is 2.839. That is, Comparative Example 1 does not satisfy the condition shown in Equation (4) of Formula 2 among the conditions of the present invention.

  From the above, Comparative Example 1 does not satisfy the conditions shown in Equations (2) and (3) of Equation 1 and Equation (4) of Equation 2 among the conditions of the present invention. Based on the above, the results of the oil consumption confirmation test under the conditions of Comparative Example 1 are shown in Table 1 together with the conditions. In Table 1, as described above, the oil consumption ratio obtained by the actual machine test using the combination of the piston rings of Comparative Example 1 is shown as the reference “1”.

[Comparative Example 2]
Comparative Example 2 is used for comparison with Example 2. In Comparative Example 2, the same engine as in Example 2 was used, and the engine was driven under the same driving conditions as in Example 2 to check the oil consumption. And the piston ring of the comparative example 2 employs a combination of three rings, a top ring, a second ring, and an oil ring, as in the second embodiment, and the outer peripheral sliding surface of the oil ring has a step land shape. Except for these points, rings having the same cross-sectional shape and material as those of the piston ring of Example 2 were used.

  In Comparative Example 2, as a combination of piston rings, conventional equivalents having different combinations of tension ratios with respect to the cylinder bore diameter of the top ring, the second ring, and the oil ring used were used. Specifically, in Comparative Example 2, the tension of each ring of the top ring, the second ring, and the oil ring, and the cylinder bore diameter were set to the conditions shown in Table 1 below. From Table 1, the combination of the piston rings of Comparative Example 2 has the following conditions.

Top ring tension A: 16N
Second ring tension B: 10N
Oil ring tension C: 44N
Cylinder bore diameter D: 94.0 mm

  In Comparative Example 2, by setting the combination of the piston rings to the above conditions, the tension ratio of the top ring or the oil ring to the cylinder bore diameter is set such that the tension (N) of the top ring is A and the tension of the oil ring ( When N) is C and the cylinder bore diameter (mm) is D, A / D is 0.170 and C / D is 0.468. That is, Comparative Example 2 does not satisfy the condition shown in Equation (2) of Formula 1 among the conditions of the present invention.

  In Comparative Example 2, by setting the combination of piston rings to the above conditions, the tension (N) of the top ring is A, the tension (N) of the second ring is B, and the tension (N) of the oil ring is When C is C and the cylinder bore diameter (mm) is D, the total tension ratio ((A + B + C) / D) of the tension ratio with respect to the cylinder bore diameter of each ring of the top ring, the second ring, and the oil ring is 0. 745. That is, Comparative Example 2 satisfies the conditions of the present invention (Equation (3) in Formula 1).

  Further, in Comparative Example 2, by setting the combination of the piston rings to the above conditions, the tension (N) of the top ring is A, the tension (N) of the oil ring is C, and the cylinder bore diameter (mm) is D. In this case, (C / D) / (A / D) is 2.750. That is, Comparative Example 2 does not satisfy the condition shown in Formula (4) of Formula 2 among the conditions of the present invention.

  From the above, Comparative Example 2 does not satisfy the conditions shown in Equation 1 (2) and Equation 2 (4) among the conditions of the present invention. Based on the above, the results of the oil consumption confirmation test under the conditions of Comparative Example 2 are shown in Table 1 together with the conditions. In Table 1, as described above, the oil consumption ratio obtained by the actual machine test using the combination of the piston rings of Comparative Example 2 is shown as the reference “1”.

[Comparative Example 3]
Comparative Example 3 is used for comparison with Example 3. In Comparative Example 3, the same engine as in Example 3 was used, and the engine was driven under the same driving conditions as in Example 3 to check the oil consumption. And the piston ring of the comparative example 3 employ | adopts the combination which consists of three top rings, a second ring, and an oil ring similarly to Example 3, and the outer periphery sliding surface of the said oil ring is a step land shape. Except for the above, all the rings having the same cross-sectional shape and material as the piston ring of Example 3 were used.

  In Comparative Example 3, as a combination of piston rings, conventional equivalents having different combinations of tension ratios with respect to the cylinder bore diameter of the top ring, the second ring, and the oil ring used were used. Specifically, in Comparative Example 3, the tension and the cylinder bore diameter of each of the top ring, the second ring, and the oil ring were set to the conditions shown in Table 1 below. From Table 1, the combination of the piston rings of Comparative Example 3 has the following conditions.

Top ring tension A: 14N
Second ring tension B: 8N
Oil ring tension C: 24N
Cylinder bore diameter D: 95.0mm

  In Comparative Example 3, by setting the combination of the piston rings to the above-described conditions, the tension ratio of the top ring or the oil ring to the cylinder bore diameter is set such that the tension (N) of the top ring is A, and the tension of the oil ring ( When N) is C and the cylinder bore diameter (mm) is D, A / D is 0.147 and C / D is 0.253. In other words, Comparative Example 3 satisfies the conditions of the present invention (Equations (1) and (2) in Formula 1).

  In Comparative Example 3, by setting the combination of the piston rings to the above conditions, the top ring tension (N) is A, the second ring tension (N) is B, and the oil ring tension (N) is When C is C and the cylinder bore diameter (mm) is D, the total tension ratio ((A + B + C) / D) of the tension ratio with respect to the cylinder bore diameter of each ring of the top ring, the second ring, and the oil ring is 0. 484. That is, Comparative Example 3 satisfies the conditions of the present invention (Equation (3) in Formula 1).

  In Comparative Example 3, by setting the combination of piston rings to the above conditions, the tension (N) of the top ring is A, the tension (N) of the oil ring is C, and the cylinder bore diameter (mm) is D. In this case, (C / D) / (A / D) is 1.714. That is, Comparative Example 3 does not satisfy the condition shown in Equation (4) of Formula 2 among the conditions of the present invention.

  From the above, Comparative Example 3 does not satisfy only the condition shown in Equation (4) of Formula 2 among the conditions of the present invention. Based on the above, the results of the oil consumption confirmation test under the conditions of Comparative Example 3 are shown in Table 1 together with the conditions. In Table 1, as described above, the oil consumption ratio obtained by the actual machine test using the combination of the piston rings of Comparative Example 3 is shown as the reference “1”.

[Contrast between Example and Comparative Example]
Comparison of Examples and Comparative Examples: In Table 1 shown below, as combinations of piston rings, tensions with respect to the cylinder bore diameter of each ring are different, and Examples 1 to 3 and Comparative Examples 1 to 3 are different. Shows the results of comparing oil consumption.

  From Table 1, the oil consumption of Examples 1 to 3 and Comparative Examples 1 to 3 in which the actual conditions of the diesel engine were 100 hours at full load (WOT) and the piston ring combination conditions were different. The quantity ratios were all the same numerical value “1”. That is, when an example (Example 1, Example 2, or Example 3) and a comparative example (Comparative Example 1, Comparative Example 2, or Comparative Example 3) are compared with the same engine and displacement, Despite the different combinations of piston rings, there was no difference in oil consumption. However, in this test, the conditions of the combination of the piston rings for Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3 are the same conditions for the engine and displacement used. As a result, the tension C of the oil ring is considerably smaller in the example (Example 1, Example 2, or Example 3) than in the comparative example (Comparative Example 1, Comparative Example 2, or Comparative Example 3). From this fact, according to the combination of the piston rings of Examples 1 to 3, the piston consumption can be increased without increasing the oil consumption with respect to the piston ring combination (Comparative Examples 1 to 3) which is a conventional equivalent. It has been found that the friction between the ring and the cylinder bore wall can be greatly reduced.

From the above results, in the combination of the piston ring consisting of a top ring, a second ring, and an oil ring used in a diesel engine, the piston ring is satisfied by satisfying the conditions specified in the present invention for the tension ratio with respect to the cylinder bore diameter of each ring. In addition to being able to suppress the variation in friction performance between the cylinder wall surface and the cylinder bore wall, it has been found that the effect of reducing friction can be obtained stably over a long period of time without increasing oil consumption .

  By using the combination of the piston ring for a diesel engine according to the present invention, it is possible to suppress the variation in friction between the piston ring used and the cylinder bore wall surface, and to stabilize the oil consumption reduction effect when driving the internal combustion engine. It will be possible to get. Therefore, the combination of the piston ring for a diesel engine according to the present invention is preferable because the oil supply frequency can be reduced, resources can be effectively used, and the environmental load can be reduced.

1 Piston Ring 2 Top Ring 3 Second Ring 4 Oil Ring 5 Coil Expander 10 Piston 20 Cylinder 21 Cylinder Bore Wall 22 Cylinder Bore

Claims (4)

In combination of piston ring consisting of top ring, second ring and oil ring used in diesel engine,
The oil ring includes an upper rail, a lower rail, and a web connecting the rails.
Outer peripheral sliding surface of the upper rail and the lower rail, and a layer formed by a layer with PVD process formed by processing gas nitriding in this order, and, symmetrically located across the web Is a step land shape in which the corner on the side facing the web is cut out in a step shape,
When the tension (N) of the top ring is A, the tension (N) of the second ring is B, the tension (N) of the oil ring is C, and the cylinder bore diameter (mm) is D, the following A combination of piston rings for a diesel engine, which satisfies the conditions of Expressions (1) to (3) shown in Formula 1.
[Equation 1]

When the top ring tension (N) is A, the oil ring tension (N) is C, and the cylinder bore diameter (mm) is D, the following equation (4) is satisfied. A combination of piston rings for a diesel engine according to claim 1.
[Equation 2]

The combination of piston rings for diesel engines according to claim 1 or 2, wherein the top ring includes at least a layer formed by gas nitriding treatment and / or a layer formed by PVD treatment on an outer peripheral sliding surface. . The combination of the piston ring for diesel engines according to any one of claims 1 to 3, wherein an outer peripheral sliding surface of the top ring has a barrel face shape.

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