JP2013053640A - Piston ring and piston - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance sealability between an inner peripheral surface of a cylinder and a piston.SOLUTION: A piston ring 31 mounted in a ring groove 22 of the piston body 11 has an annular member 32 having an inner peripheral face 33, an outer peripheral face 34, and side faces 35, 36 continuous in an annular shape. The annular member 32 is mounted in the ring groove 22 while enlarging the diameter of the inner peripheral face 33 outward in a radial direction and reducing the diameter of the outer peripheral face 34 inward in the radial direction such that the side faces 35, 36 form conical faces. An inside seal part 41 is formed at the inner peripheral face corner part of the annular member 32, the inside seal part 41 comes into contact with the bottom face of the ring groove 22. An outside seal part 42 is formed at an outer peripheral corner part of the annular member, the outside seal part 42 comes into contact with the inner peripheral face of the cylinder 15. The piston ring 31 comprising the annular member 32 comes into contact with the bottom face of the ring groove 22 and the inner peripheral face of the cylinder 15.

Description

  The present invention relates to a piston ring mounted in an annular groove formed on an outer peripheral surface of a piston, and a piston to which the piston ring is mounted.

  The engine has a crankshaft rotatably mounted in the crankcase and a piston that linearly reciprocates within the cylinder. The piston is connected to the crankshaft by a connecting rod, and the crankshaft is rotationally driven by the reciprocation of the piston by combustion gas. A plurality of ring grooves are formed on the outer peripheral surface of the piston, and a piston ring is attached to each ring groove. The piston ring has a function of sealing the combustion gas and scraping off the lubricating oil in the crank chamber, and further has a role of transmitting the heat of the piston to the cylinder.

  A piston ring that is mounted to seal combustion gas to a piston is called a compression ring. On the other hand, a piston ring that is mounted to scrape off the lubricating oil is called an oil ring. When two compression rings are attached to the piston, the ring on the top surface side of the piston is said to be the top ring, the ring on the connecting rod side is said to be the second ring, and the oil ring is the second ring. Installed next to each other. In a large diesel engine, three compression rings may be mounted, and the third compression ring is called a third ring. As described above, the normal piston includes a type in which three piston rings are mounted and a type in which two piston rings are mounted.

  The piston ring is formed in an annular shape by a metal rod having a certain length, and both end faces are opposed to each other through a joint portion. If the piston ring is provided with the mating portion, the blow-by gas in the combustion chamber flows out into the crank chamber through the mating portion, and the lubricating oil in the crank chamber easily flows into the combustion chamber. Therefore, a piston ring integrated in an annular shape without having an abutment portion has been developed as described in Patent Documents 1 to 3.

JP 2009-24530 A Japanese Patent No. 3244396 JP-A-8-312781

  Patent Document 1 describes a synthetic resin bundling that is integrally formed in an annular shape. In order to attach the bundling to the ring groove, it is necessary to elastically deform the bundling so as to spread outward in the radial direction. Yes, the cylinder is pressed against the inner peripheral surface of the cylinder by thermal expansion. Patent Document 2 describes a piston ring in which an annular synthetic resin ring is pressed radially outward by an expand ring, and an elastic ring is disposed between the synthetic resin ring and the expand ring. Has been. Furthermore, Patent Document 3 describes a synthetic resin ring that is bent into a U-shape, and improves the wear resistance by generating a bending stress on a sliding surface that contacts the cylinder.

  As described in each of the patent documents, when the piston ring is an integral type connected in an annular shape, there is no abutment, so blow-by gas flows out into the crank chamber through that portion, or lubricating oil Inflowing toward the combustion chamber can be prevented. However, in the type in which the bundling is installed in the ring groove so as to expand in the radial direction as in the bundling described in Patent Document 1, the bundling is applied to the inner peripheral surface of the cylinder with a strong pressing force. The sliding contact is not possible. It is made to adhere by thermal expansion, and cannot perform a sealing function at a low engine temperature.

  As described in Patent Document 2, when the piston ring has a three-part configuration of a synthetic resin ring, an expand ring, and an elastic ring, the pressure on the inner peripheral surface of the cylinder depends on a very small amount of thermal expansion. Therefore, it is difficult to manage the dimensions, and the manufacturing cost is increased. Furthermore, in the piston ring described in Patent Document 3, it is necessary to blend reinforcing fibers in order to improve wear resistance, and the piston ring cannot be manufactured at low cost.

  Moreover, even in the case of an integrated piston ring, in order for the piston ring to be brought into sliding contact with the inner surface of the cylinder, that is, the cylinder bore, it is necessary to accommodate the piston ring in the ring groove so that the piston ring can be slid radially outward. For this reason, a slight gap is provided between the piston ring and the ring groove. For this reason, there is a limit in improving the sealing performance between the piston ring and the piston.

  The objective of this invention is providing the piston for engines which can improve the sealing performance with the internal peripheral surface of a cylinder.

  Another object of the present invention is to provide a piston ring that enhances the sealing performance between the piston ring and the piston.

  A piston ring according to the present invention is a piston ring that is mounted in a ring groove of a piston, and has an inner peripheral surface, an outer peripheral surface, and a side surface that are annularly connected, and is formed of an elastic body having a quadrilateral cross section. The ring groove includes an annular member that expands the inner peripheral surface radially outward so as to be a conical surface, and is attached to the ring groove by reducing the outer peripheral surface radially inward. An inner seal portion that contacts the bottom surface of the annular member is formed at the inner peripheral surface corner portion of the annular member, and an outer seal portion that contacts the inner peripheral surface of the cylinder is formed at the outer peripheral surface corner portion of the annular member. . The piston ring of the present invention is characterized in that the annular member is formed of a fluororesin. The piston ring according to the present invention is characterized in that the annular member is used as an oil ring for scraping off the lubricating oil in the crank chamber. The piston ring of the present invention is characterized in that the outer seal portion is disposed closer to the crank chamber than the inner seal portion.

  A piston according to the present invention is a piston that reciprocates in a cylinder of an engine in an axial direction to rotate a crankshaft, and includes a piston main body having a ring groove formed on an outer peripheral surface, and a piston ring attached to the ring groove. The piston ring has an inner peripheral surface, an outer peripheral surface, and a side surface that are connected in an annular shape, and is formed of an elastic body having a quadrilateral cross section, and the inner peripheral surface is formed so that the side surface is a conical surface. The annular seal member has an annular member attached to the ring groove by expanding the diameter outward in the radial direction and reducing the diameter of the outer peripheral surface inward in the radial direction. An outer seal portion formed at an inner peripheral surface corner of the member and contacting the inner peripheral surface of the cylinder is formed at an outer peripheral surface corner of the annular member. The piston of the present invention is characterized in that the annular member is formed of a fluororesin. The piston of the present invention is characterized in that the annular member is used as an oil ring that scrapes off the lubricating oil in the crank chamber. The piston of the present invention is characterized in that the outer seal portion is disposed closer to the crank chamber than the inner seal portion.

  In the present invention, the piston ring has an inner seal portion that contacts the bottom surface of the ring groove and an outer seal portion that contacts the inner peripheral surface of the cylinder. The lubricating oil can be prevented from flowing. Thereby, the sealing performance between the piston and the cylinder can be improved, and the durability of the engine can be improved.

  A piston ring having an inner seal portion and an outer seal portion can be formed by elastically deforming an annular member having a quadrangular cross section having an inner peripheral surface, an outer peripheral surface, and a side surface, so that the piston ring is manufactured at low cost. be able to.

It is sectional drawing which shows the piston which is one embodiment of this invention. It is an expanded sectional view of the A section in FIG. It is a principal part expanded sectional view which shows the piston ring shown by FIG. (A)-(C) are process drawings which show the assembly method to the piston main body of a piston ring. It is a principal part expanded sectional view which shows the piston ring with which the piston which is other embodiment of this invention is mounted | worn. It is sectional drawing which shows a part of piston which is another embodiment of this invention, respectively.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the piston 10 has a piston body 11 made of aluminum alloy. A piston pin hole 12 is formed in the piston body 11, and one end of the connecting rod 14 is connected to the piston body 11 by a piston pin 13 fitted in the piston pin hole 12. The piston 10 is incorporated in a cylinder bore formed in the cylinder 15 of the engine so as to be reciprocally movable in the axial direction. A reciprocating motion of the piston 10 causes a crankshaft (not shown) connected to the piston 10 by the connecting rod 14 to rotate. Is done. The top surface 16 side of the piston body 11 is a combustion chamber 17, and the skirt portion 18 side is a crank chamber 19.

  Two ring grooves 21 and 22 are formed on the outer peripheral surface of the piston body 11 shown in FIG. The ring groove 21 is a compression ring groove, and a land portion 24 a is formed between the top surface 16 and the ring groove 21. The ring groove 22 is an oil ring groove, and a land portion 24 b is formed between the ring groove 21 and the ring groove 22.

  A piston ring 26 as a compression ring is mounted in the ring groove 21. The piston ring 26 is formed in an annular shape by a metal material having a certain length so that both end faces are opposed to each other through the joint portion. As the metal material, spring steel, stainless steel, spheroidal graphite cast iron or the like is used. As shown in FIG. 2, the outer peripheral surface of the piston ring 26 is curved in an arc shape, and the radial surface of the ring groove 21 and the side surface of the piston ring 26 are arranged so that the piston ring 26 can slide in the radial direction. A gap 27 is provided between them, and a gap 28 is provided between the bottom surface of the ring groove 21 and the inner peripheral surface of the piston ring 26. However, the outer peripheral surface of the piston ring 26 may be tapered.

  A piston ring 31 as an oil ring is mounted in the ring groove 22. The piston ring 31 is formed by an annular member 32 made of an elastic body having a quadrilateral cross section. As shown in FIGS. 4A and 4B, the annular member 32 has an inner peripheral surface 33, an outer peripheral surface 34, and side surfaces 35, 36 on both sides that are annularly connected, and the cross section is a quadrilateral, that is, a rectangle. Yes. As the material of the annular member 32 shown in the figure, a fluororesin such as tetrafluoroethylene polymer (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE) or the like is used. Yes.

  As shown in FIG. 4 (A), the annular member 32 formed in a ring shape is elastically deformed and attached to the ring groove 22 as shown in FIG. 4 (C). As shown by an arrow in FIG. 4 (B), the annular member 32 expands the inner peripheral surface 33 radially outward, while the outer peripheral surface 34 contracts radially inward. As shown in C), both side surfaces 35 and 36 are elastically deformed so as to be conical surfaces close to the cylindrical surface. The cross-sectional shape of the annular member 32 is a rectangle in which the dimensions of the side surfaces 35 and 36 are larger than the axial dimensions of the inner peripheral surface 33 and the outer peripheral surface 34, and the long side surfaces 35 and 36 are cylindrical. When the annular member 32 is elastically deformed so as to have a close conical surface, the annular member 32 has a “C” shape. Thereby, the one side surface 35 before elastic deformation becomes an outer side surface as a conical surface, and forms a sliding surface of the piston ring. The other side surface 36 before deformation is an inner side surface as a conical surface. As a result, as shown in FIG. 3, the inner seal portion 41 is formed at the corner of the inner peripheral surface where the inner peripheral surface 33 and the inner side surface 36 intersect, and the outer periphery where the outer peripheral surface 34 and the outer side surface 35 intersect. An outer seal portion 42 is formed at the corner of the surface.

  As shown in FIG. 4, the piston ring 31 has a step of forming an annular member 32 having a quadrilateral cross section, as shown in FIGS. 4 (A) and 4 (B), and the annular member 32 as shown in FIG. 4 (C). The piston ring 31 having the inner seal portion 41 and the outer seal portion 42 can be easily manufactured at a low cost by the step of elastically deforming into a conical shape.

  As shown in FIG. 3, the inner seal portion 41 comes into line contact with the bottom surface of the ring groove 22 when a piston ring 31 as an oil ring is attached to the ring groove 22. As shown in FIG. 3, the outer seal portion 42 comes into line contact with the inner peripheral surface of the cylinder 15 when the piston 10 with the piston ring 31 attached is incorporated into the cylinder 15. As a result, the inner seal portion 41 comes into contact with the bottom surface of the ring groove 22 toward the radially inner side as indicated by an arrow in FIG. Is in contact with the inner peripheral surface of the cylinder 15 so as to be pressed radially outward.

  As shown in FIG. 2, the outer seal portion 42 is disposed closer to the crank chamber 19 than the inner seal portion 41. Accordingly, when the piston 10 moves downward in FIG. 2, the wedge effect is less than when the piston 10 moves upward, so that the lubricating oil between the outer seal portion 42 and the inner peripheral surface of the cylinder 15 is scraped. I will drop it. The portion where the outer peripheral surface 34 and the inner side surface 36 intersect is a contact portion 43 that contacts the radial surface of the ring groove 22, and the portion where the inner peripheral surface 33 and the outer side surface 35 intersect is the ring groove. The contact portion 44 is in contact with the radial surface on the opposite side of 22. A slight gap is formed between the respective contact portions 43 and 44 and the upper and lower radial surfaces of the ring groove 22 and the piston ring 31 so that the piston ring 31 is elastically deformed in the ring groove 22 smoothly. ing. For this reason, blow-by gas and lubricating oil in the crank chamber 19 may be mixed into the bottom surface of the ring groove 22, but the inner seal portion 41 is in contact with the bottom surface of the ring groove 22. The lubricating oil is prevented from flowing toward the piston ring 26.

  In this way, the piston ring 31 is elastically deformed inside the ring groove 22 while the piston 10 is driven, and the inner seal portion 41 of the piston ring 31 is in line contact with the bottom surface of the ring groove 22. The sealing property between the two can be improved. Thereby, the sealing performance between the combustion chamber 17 and the crank chamber 19 in the piston 10 for the engine can be improved, and the durability of the engine can be improved. Moreover, the shape of the piston ring 31 is simple and can be manufactured at low cost.

  FIG. 5 is a cross-sectional view showing a piston according to another embodiment of the present invention, and shows the same portion as FIG. 3 of the piston.

  Unlike the case shown in FIG. 3, the piston ring 31 shown in FIG. 5 is arranged in the ring groove 22 so that the outer seal portion 42 is closer to the combustion chamber 17 than the inner seal portion 41. As a result, when the piston 10 moves upward in FIG. 5, the outer seal portion 42 comes into sliding contact so as to be strongly pressed against the inner peripheral surface of the cylinder 15 than when it moves downward. . As described above, the piston ring 31 is arranged in the form in which the outer seal portion 42 is arranged on the crank chamber 19 side as shown in FIG. 3 and the form in which the outer seal portion 42 is arranged on the combustion chamber 17 side as shown in FIG. is there. When the piston ring 31 is used as an oil ring, it is considered that the effect of scraping off the lubricating oil is enhanced if the outer seal portion 42 is disposed on the crank chamber 19 side. On the other hand, when the piston ring 31 is used as a compression ring, it is considered that the effect of preventing the passage of blow-by gas is further enhanced if the outer seal portion 42 is disposed on the combustion chamber 17 side. However, when the piston ring 31 is used as a compression ring, a metal such as spring steel or stainless steel is used as the material.

  FIG. 6 is a cross-sectional view showing a part of a piston 10 according to another embodiment. Three ring grooves 21 to 23 are formed on the outer peripheral surface of the piston main body 11 of the piston shown in FIG. 6, and the first ring groove 21 from the combustion chamber 17 side is a top ring, and the second The ring groove 22 is a second ring. Two piston rings 26a and 26b as compression rings shown in FIG. 2 are mounted in the ring grooves 21 and 22, respectively. A piston ring 31 similar to that shown in FIG. 3 is mounted in the ring groove 23 as the third oil ring. Thus, the present invention can also be applied to a piston to which three piston rings are attached. As an arrangement form of the piston ring 31 shown in FIG. 6, the outer seal part 42 may be arranged on the combustion chamber 17 side as shown in FIG. 5.

  In the piston ring 31, the inner seal portion 41 is in line contact with the bottom surface of the ring groove 22, and the outer seal portion 42 is in line contact with the inner peripheral surface of the cylinder 15, thereby improving the sealing performance between the piston 10 and the cylinder 15. Can do. Moreover, since the piston ring 31 has a simple shape and can be manufactured at low cost, the flow of blow-by gas from the combustion chamber to the crank chamber can be eliminated, thereby eliminating or simplifying the blow-by gas recirculation device. Thus, the environment can be protected and an environment-friendly engine can be obtained at low cost.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. In the illustrated embodiment, the piston ring of the present invention is applied as an oil ring, but it can also be applied as a compression ring.

DESCRIPTION OF SYMBOLS 10 Piston 11 Piston main body 14 Connecting rod 15 Cylinder 17 Combustion chamber 19 Crank chamber 21-23 Ring groove 26 Piston ring 31 Piston ring 32 Annular member 33 Inner peripheral surface 34 Outer peripheral surface 35, 36 Side surface 41 Inner seal part 42 Outer seal part 43 44 Contact part

Claims (8)

A piston ring mounted in the ring groove of the piston,
Each of the inner peripheral surface, the outer peripheral surface and the side surface that are continuous in an annular shape has a cross-section made of an elastic body having a quadrilateral shape, and the inner peripheral surface is radially expanded so that the side surface becomes a conical surface, Having an annular member that is mounted on the ring groove by reducing the diameter of the outer peripheral surface radially inward;
Forming an inner seal portion in contact with the bottom surface of the ring groove at a corner of the inner peripheral surface of the annular member;
An outer seal portion that contacts an inner peripheral surface of a cylinder is formed at a corner portion of the outer peripheral surface of the annular member.   The piston ring according to claim 1, wherein the annular member is made of a fluororesin.   3. The piston ring according to claim 1, wherein the annular member is used as an oil ring that scrapes off lubricating oil in a crank chamber.   The piston ring according to any one of claims 1 to 3, wherein the outer seal portion is disposed closer to a crank chamber than the inner seal portion. A piston that reciprocates in the cylinder of the engine in the axial direction and rotates the crankshaft,
A piston body having a ring groove formed on the outer peripheral surface;
A piston ring mounted in the ring groove;
The piston ring has an inner peripheral surface, an outer peripheral surface, and a side surface that are continuous in an annular shape, and is formed of a quadrilateral elastic body, and the inner peripheral surface is radially outward so that the side surface is a conical surface. While expanding the diameter, the outer peripheral surface has an annular member that is radially inwardly attached to the ring groove,
Forming an inner seal portion in contact with the bottom surface of the ring groove at a corner of the inner peripheral surface of the annular member;
The piston characterized by forming the outer seal part which contacts the inner peripheral surface of a cylinder in the outer peripheral surface corner part of the said annular member.   6. The piston according to claim 5, wherein the annular member is made of a fluororesin.   The piston according to claim 5 or 6, wherein the annular member is used as an oil ring that scrapes off lubricating oil in a crank chamber.   The piston according to any one of claims 5 to 7, wherein the outer seal portion is disposed closer to a crank chamber than the inner seal portion.

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