JP2008014223A - Piston for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce blow-by gas through the joint clearance of a piston ring for a long period. <P>SOLUTION: A resin-made heat-resistant elastic member 9 is fixedly provided in a ring groove 3 of a piston 2 so that the resin-made heat-resistant elastic member 9 is placed between a pair of joint end faces 6a and 6b of the piston ring set in the ring groove 3. Further, the resin-made heat-resistant elastic member 9 is preferably inserted and fixed in a stationary groove formed on the surface of the ring groove 3 of the piston 2. Furthermore, the resin-made heat-resistant elastic member 9 is preferably in contact with the inner circumferential surface 1a of the cylinder 1 at least when the engine is started. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a piston for an internal combustion engine that is effective in reducing blow-by gas.

  Piston rings are mounted in a plurality of ring grooves on a piston that reciprocates in a cylinder of an internal combustion engine. A compression ring, which is a type of piston ring, maintains a good airtightness between the cylinder and the piston. That is, it has a function of preventing gas leakage at the time of compression, maintaining a specified compression pressure, and preventing combustion gas from leaking from the combustion chamber at the time of combustion. The compression ring is used as a top ring attached to a portion closest to the piston top surface or a second ring attached to a portion next to the piston top surface next to the top ring. The compression ring is an annular member having an abutment at one location. The abutment is set to an appropriate size so that the end of the abutment does not abut due to thermal expansion of the ring during operation. Gas leaks from this gap. This leakage gas is generally called blow-by gas. In addition, oil rises through the gap.

In order to solve the above problem, for example, Patent Document 1 discloses a structure in which a heat-resistant elastic material such as heat-resistant rubber is fixed to the end face of the piston ring by baking or bonding to reduce blow-by gas. Yes. Patent Document 2 discloses a structure for reducing blow-by gas by providing a soft metal or non-metal layer on the end face of the piston ring by mechanical joining, adhesion, thermal spraying, plating, or the like. .
Japanese Utility Model Publication No. 53-153109 Japanese Utility Model Publication No. 54-73408

However, in the structure disclosed in Patent Document 1, since the piston ring repeatedly moves up and down within the ring groove of the piston, the heat-resistant elastic material is likely to drop off from the piston ring, which is a problem in terms of durability. It becomes. Further, the structure disclosed in Patent Document 2 has the same problem.

  An object of the present invention is to reduce blow-by gas through a joint gap of a piston ring over a long period of time.

In order to solve the above problems, the present invention employs the following means. That is,
The present invention is characterized in that a resin heat-resistant elastic member is fixed to a ring groove of a piston, and the resin heat-resistant elastic member is disposed between a pair of mating end faces of a piston ring mounted in the ring groove. This is a piston for an internal combustion engine.

  The heat-resistant elastic member made of resin is preferably inserted into a fixed groove formed on the ring groove surface of the piston.

  The heat-resistant elastic member made of resin is preferably in contact with the pair of mating end surfaces of the piston ring at least during engine operation.

  The heat-resistant elastic member made of resin is preferably in contact with the inner peripheral surface of the cylinder at least during engine operation.

  In the present invention, when the engine is operated, the pair of mating end surfaces of the piston ring are brought into contact with the heat-resistant elastic member made of resin so that there is no gap between the piston ring mating portions. Blow-by gas can be reduced. Even if the end face of the mating end of the piston ring comes into contact with the heat-resistant elastic member made of resin, the piston ring can follow the inner peripheral surface of the cylinder without being deformed by the elastic action of the heat-resistant elastic member made of resin. Further, when the engine is operated, the heat-resistant elastic member made of resin is brought into contact with the inner peripheral surface of the cylinder, so that blow-by gas can be further reduced. The contact between the heat-resistant elastic member made of resin and the end face of the piston ring and the contact between the heat-resistant elastic member made of resin and the inner circumferential surface of the cylinder may be performed at least during engine operation. In some cases, the piston with the piston ring attached may be brought into contact with the cylinder. In addition to the above-mentioned reduction of blow-by gas, it is possible to reduce an oil rising phenomenon in which oil enters the combustion chamber from the crankcase side, and an oil consumption reduction effect can be obtained.

By fixing the heat-resistant elastic member made of resin in the ring groove, even if the piston ring repeatedly moves up and down in the ring groove, the heat-resistant elastic member made of resin is difficult to drop off and has excellent durability. It is desirable in terms of durability that the heat-resistant elastic member made of resin should be treated with resin coating, ion plating film, plating, etc. on the part that contacts the end face of the piston ring and the part that contacts the cylinder. .

  The resin heat-resistant elastic member is fixed to the ring groove by mechanical joining or adhesion. Since the piston is exposed to high heat from the combustion gas or at low temperatures when the engine is stopped, the piston is contracted due to thermal expansion. If a fixing groove is provided on the ring groove surface and a heat resistant elastic member made of resin is inserted into the groove and fixed, it is difficult to be affected by dimensional changes due to thermal expansion, which is preferable in terms of durability. Further, it is desirable to use a material having a thermal expansion coefficient close to that of the piston as the material of the heat-resistant elastic member made of resin.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, a plurality of ring grooves 3, 4, and 5 are formed on the outer peripheral surface of a piston 2 that reciprocates within a cylinder 1 of an internal combustion engine. Piston rings 6, 7, and 8 are attached to the respective parts. The piston ring is a top ring 6, a second ring 7, and an oil ring 8 in order from the side closer to the combustion chamber. The top ring 6 and the second ring 7 have a function of a compression ring and mainly suppress blow-by gas from the combustion chamber, but also prevent oil from entering the combustion chamber.

  The top ring 6 is an annular member having an abutment, and a heat-resistant elastic member 9 made of resin for filling the gap is arranged in a gap between a pair of facing end surfaces 6a and 6b facing each other. Has been. The heat-resistant elastic member 9 made of resin is a rectangular heat-resistant elastic plate, is attached to the ring groove 3, and is closely fixed to the upper and lower surfaces and the bottom surface of the ring groove 3 with an adhesive without any gap. Note that the heat-resistant elastic member 9 made of resin is preferably fixed in close contact with the ring groove 3 without a gap, but is not limited thereto.

Regarding the thickness of the resin heat-resistant elastic member 9 in the circumferential direction of the ring groove 3, in this embodiment, when the piston 2 with the top ring 6 is attached to the cylinder 1, the pair of mating end faces of the top ring 6. 6a, 6b has a slight gap between the heat-resistant elastic member 9 made of resin, and the pair of mating end surfaces 6a, 6b are in contact with the heat-resistant elastic member 9 made of resin when the engine is operated. However, when the piston 2 with the top ring 6 is attached to the cylinder 1, the pair of mating end surfaces 6 a, 6 b of the top ring 6 may be dimensioned to abut against the heat-resistant elastic member 9 made of resin.

  Further, the length of the resin heat resistant elastic member 9 in the radial direction of the ring groove 3 is such that the thickness of the top ring 6 in the radial direction is such that the resin heat resistant elastic member 9 is disposed at the entire joint portion of the top ring 6. It is preferable that it has the dimension more than this. In this embodiment, when the piston 2 with the top ring 6 is attached to the cylinder 1, there is a slight gap between the heat-resistant elastic member 9 made of resin and the inner peripheral surface of the cylinder 1. A heat-resistant elastic member 9 made of resin is brought into contact with the inner peripheral surface 1 a of the cylinder 1. However, when the piston 2 to which the top ring 6 is attached is attached to the cylinder 1, the resin heat-resistant elastic member 9 may come into contact with the inner peripheral surface 1 a of the cylinder 1. The front end surface of the heat-resistant elastic member 9 made of resin that contacts the inner peripheral surface of the cylinder 1 is an arc surface along the inner peripheral surface of the cylinder 1.

  The length of the resin heat-resistant elastic member 9 in the vertical direction of the ring groove 3 is the axial width of the top ring 6 so that the resin heat-resistant elastic member 9 is disposed in the entire joint portion of the top ring 6. It is preferable to have the above dimensions.

  FIG. 3 shows another embodiment of the present invention. In this embodiment, the resin heat-resistant elastic member 9 is more securely fixed to the ring groove 3. In the present embodiment, a rectangular fixing groove 10 into which a part of the resin heat resistant elastic member 9 is inserted is formed on the lower surface of the ring groove 3. The heat-resistant elastic member 9 made of resin is formed longer than that described in the above embodiment by the length of the portion inserted into the fixed groove 10 in the vertical direction of the ring groove 3, and other configurations are the same as in the above embodiment. Is the same.

  The heat-resistant elastic member 9 made of resin according to the present embodiment is more securely fixed to the ring groove 3 by being inserted and fixed in the fixing groove 10, and cannot be moved in the circumferential direction. 9 is prevented from falling off. The heat-resistant elastic member 9 made of resin may be simply inserted into the fixing groove 10, but, of course, as in the above-described embodiment, the upper surface and the bottom surface of the ring groove 3 and the fixing groove 10 are closely fixed with an adhesive without any gap. It is preferable to do this.

  Moreover, in this embodiment, although the example which provided the fixing groove 10 of the heat-resistant elastic member 9 made from resin in the lower surface of the ring groove 3 was shown, it is not restricted to this, The upper surface of a ring groove, the bottom surface of a ring groove, Resin heat-resistant elastic members may be inserted and fixed on the upper and lower surfaces of the ring groove or on the upper and lower surfaces and the bottom surface of the ring groove.

  FIG. 4 shows yet another embodiment of the present invention. This embodiment is an example in which the heat-resistant elastic member 9 made of resin does not come into contact with the inner peripheral surface 1a of the cylinder 1 when the engine is operated.

  In the above embodiment, the example in which the heat-resistant elastic member made of resin is mounted on the top ring groove is shown, but the present invention is not limited to this.

It is a longitudinal cross-sectional view which shows the cylinder part of the internal combustion engine equipped with the piston which is one Embodiment of this invention. 1 shows the top ring portion of FIG. 1, (a) is a plan sectional view, (b) is a sectional view taken along line BB in the diagram of (a), and (c) is a sectional view taken along line CC in the diagram of (a). It is. 2 shows another example of a heat-resistant elastic member made of resin, corresponding to FIG. 2, (a) is a plan sectional view, (b) is a sectional view taken along line BB in FIG. It is CC sectional view taken on the line of the figure of (a). 2 shows another example of a heat-resistant elastic member made of resin, corresponding to FIG. 2, (a) is a cross-sectional plan view, (b) is a cross-sectional view taken along line BB in FIG. FIG. 5 is a sectional view taken along line CC in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 1a Cylinder inner peripheral surface 2 Piston 3, 4, 5 Ring groove 6 Top ring 7 Second ring 8 Oil ring 9 Heat resistant elastic member 10 made of resin Fixing groove

Claims (4)

  A heat resistant elastic member made of resin is fixed to a ring groove of a piston, and the heat resistant elastic member made of resin is disposed between a pair of end faces of a piston ring mounted in the ring groove. piston.   The piston for an internal combustion engine according to claim 1, wherein the heat-resistant elastic member made of resin is inserted into a fixed groove formed on a ring groove surface of the piston.   3. The piston for an internal combustion engine according to claim 1, wherein the heat-resistant elastic member made of resin abuts against a pair of mating end surfaces of the piston ring at least during engine operation.   4. The piston for an internal combustion engine according to claim 1, wherein the heat-resistant elastic member made of resin abuts on an inner peripheral surface of a cylinder at least when the engine is operated.

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