JP2013011205A - Reciprocating engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reciprocating engine for reducing frictional resistance of a piston and a cylinder, by supporting the piston by high pressure gas (floating by gas pressure), by restraining temperature lowering of high temperature-high pressure combustion gas introduced into a gas chamber, in its turn, reduction in the gas pressure.SOLUTION: This reciprocating engine 1 introduces the high temperature-high pressure combustion gas 12 above the piston 2 from a gas passage hole 21 arranged in an upper part 20 on the thrust side 10 of a cylinder inner surface 8 in the initial stage of an expansion stroke, to the gas chamber 4 formed by being surrounded by a top ring 5, a second ring 6 and second land 7 of the piston 2 and the cylinder inner surface 8, and supports the piston 2 from the thrust side 10 by this introduced high temperature-high pressure combustion gas 12, and forms a coating film layer 14 of high heat insulation performance on a surface 13 of the second land 7 of the piston 2.

Description

  The present invention relates to a reciprocating engine in which the piston is supported by high-temperature and high-pressure combustion gas (gas pressure float) against the side pressure acting on the piston in the explosion and expansion stroke, and the frictional resistance between the piston and the cylinder is reduced.

  In Patent Documents 1 to 4, a gas chamber is formed in the second land portion of the piston, and at the beginning of the explosion / expansion stroke, high-temperature and high-pressure combustion gas above the piston is introduced into this gas chamber from a gas passage hole provided in the cylinder inner surface. And a technique for reducing the frictional resistance between the piston and the inner surface of the cylinder by supporting the piston from the thrust side with the introduced high-temperature and high-pressure combustion gas.

International Publication No. 92/02722 International Publication No. 2004/079177 European Patent Application Publication No. 1878901 International Publication No. 2008/047453

  However, in the above technique, while the engine is running, the high-temperature and high-pressure combustion gas above the piston is repeatedly introduced, held, and discharged in the gas chamber, but the gas chamber has a large surface area surrounding the gas pressure for a small volume. Therefore, when the introduced high-temperature high-pressure combustion gas is introduced into the gas chamber, the temperature is lowered, and the gas pressure is lowered, so that the supporting force of the piston is lowered.

  In view of this, the present invention suppresses the decrease in the temperature of the high-temperature and high-pressure combustion gas introduced into the gas chamber and thus the decrease in the gas pressure, supports the piston with the high-pressure gas (gas pressure float), and the friction resistance between the piston and the cylinder. It is intended to provide a reciprocating engine in which

  In the present invention, a gas chamber surrounded by a piston top ring, a second ring, a second land, and a cylinder inner surface is provided with a gas passage hole provided in an upper portion on the thrust side of the cylinder inner surface in the initial stage of the expansion stroke. In a reciprocating engine in which high-temperature high-pressure combustion gas above the piston is introduced and the piston is supported from the thrust side by the introduced high-temperature high-pressure combustion gas, a highly heat-insulating coating layer is formed on the surface of the second land of the piston Reciprocating engine.

  The coating layer may be formed by thermal spraying a material having low thermal conductivity (high thermal insulation) such as stainless steel or ceramic.

  The coating layer may be a multilayer coating layer composed of two or more layers.

  Although the surface of the coating layer exposed to the high-temperature and high-pressure combustion gas introduced into the gas chamber by the operation of the reciprocating engine of the present invention becomes hot due to its heat insulation effect, heat transfer to the inside of the piston (heat escape) Is small. That is, the high-temperature and high-pressure combustion gas introduced into the gas chamber is exposed to the surface of the coating layer that has reached a high temperature, and heat escape into the piston due to the heat insulating effect (low thermal conductivity effect) of the coating layer is small. For this reason, the introduced high-temperature and high-pressure combustion gas is suppressed from lowering the temperature in the gas chamber. Therefore, the high-pressure gas is maintained and the piston is sufficiently supported from the thrust side (gas pressure float). The frictional resistance is sufficiently reduced.

FIG. 1 is an explanatory cross-sectional view of a reciprocating engine according to an embodiment of the present invention. FIG. 2 is a side view of the piston shown in FIG.

  Embodiments of the present invention will be described below based on examples shown in the drawings. The present invention is not limited to these examples.

  FIG. 1 shows an initial state of the lowering process of the piston 2 in the explosion / expansion stroke.

  FIG. 1 shows a reciprocating engine 1 of this embodiment in the initial stage of an explosion / expansion stroke, and FIG. 2 shows a piston 2 of the reciprocating engine 1 of FIG. 3 is a cylinder, and 4 is a gas chamber. The gas chamber 4 is formed by being surrounded by a top ring 5, a second ring 6, a second land 7, and a cylinder inner surface 8 of the piston 2. The gas chamber 4 has a vertical width 9 wide on the thrust side 10 and narrow on the anti-thrust side 11.

  This is because the piston 2 is supported from the thrust side 10 by the high-temperature and high-pressure combustion gas 12 that is introduced and held by increasing the area receiving the gas pressure on the thrust side 10 and decreasing it on the anti-thrust side 11 (to oppose the piston side pressure). In order to minimize the push-back from the anti-thrust side 11.

  The second land 7 is arranged on the surface of the piston 2 between the groove of the top ring 5 and the groove of the second ring 6, and the vertical width 9 is wide on the thrust side 10 and narrow on the anti-thrust side 11. Yes.

  On the surface 13 of the second land 7 of the piston 2, a coating layer 14 having low thermal conductivity (high thermal insulation) is formed.

  The coating layer 14 is formed by spraying a material having high heat resistance and heat insulation such as stainless steel and ceramic.

  As shown in FIG. 1, the top ring 5 that forms the gas chamber 4 of the piston 2 of the reciprocating engine 1 of the present embodiment is provided in parallel with the piston top surface 15, while the second ring 6. Is inclined downward toward the thrust side 10. That is, the second ring 6 is provided farther away from the top ring 5 on the thrust side 10 and closer to the anti-thrust side 11.

  Therefore, the distance (distance) between the top ring 5 and the second ring 6, that is, the vertical width 9 of the gas chamber 4 is wide on the thrust side 10 and gradually becomes narrower as it approaches the anti-thrust side 11.

  A plurality of gas passage holes 21 are provided in the upper portion 20 of the thrust side 10 of the cylinder inner surface 8. In the downward stroke of the piston 2, when the top ring 5 of the piston 2 passes over the gas passage hole 21, the combustion chamber 23 above the piston 2 and the gas chamber 4 of the piston 2 through the recess 22 of the gas passage hole 21. And the high-temperature and high-pressure combustion gas 12 in the combustion chamber 23 is introduced and held in the gas chamber 4.

  That is, when the top ring 5 of the piston 2 passes through the gas passage hole 21 in the upper portion 20 of the cylinder inner surface 8 in the initial stage of the explosion / expansion stroke, the combustion chamber 23 above the piston 2 and the gas chamber 4 of the piston 2 are separated. The high-temperature and high-pressure combustion gas 12 is introduced and held in the gas chamber 4.

  At this time, the piston 2 tends to be pressed against the cylinder inner surface 8 against the thrust side 10 under the action of the side pressure, but is supported from the thrust side 10 by the high-temperature high-pressure combustion gas 12 introduced and held in the gas chamber 4 (piston 2 Descent in a counter-acting state).

  In the reciprocating engine 1 of the present invention, a coating layer 14 having a low thermal conductivity (high thermal insulation effect) is formed on the surface 13 of the second land 7 of the piston 2 forming the gas chamber 4. The surface of the coating layer 14 becomes hot due to its heat insulating effect, but heat transfer (heat escape) to the inside of the piston 2 is small. That is, the high-temperature and high-pressure combustion gas 12 introduced into the gas chamber 4 is exposed to the surface of the coating layer 14 that has reached a high temperature, and heat generated inside the piston due to the heat insulation effect (low thermal conductivity effect) of the coating layer 14. The escape is small. For this reason, the introduced high-temperature high-pressure combustion gas 12 is kept in a high-temperature state by suppressing a temperature drop in the gas chamber. Accordingly, the high pressure gas is maintained, the piston 2 is sufficiently supported from the thrust side 10 (gas pressure float), and the frictional resistance between the piston 2 and the cylinder inner surface 8 is sufficiently reduced.

DESCRIPTION OF SYMBOLS 1 Reciprocating engine 2 Piston 3 Cylinder 4 Gas chamber 5 Top ring 6 Second ring 7 Second land 8 Cylinder inner surface 9 Vertical width 10 Thrust side 11 Anti-thrust side 12 High temperature high pressure combustion gas 13 Surface 14 Film layer 15 Piston top surface

Claims (4)

  In the gas chamber surrounded by the piston's top ring, second ring, second land, and cylinder inner surface, the high temperature above the piston from the gas passage hole provided in the upper part on the thrust side of the cylinder inner surface in the initial stage of the expansion stroke. In a reciprocating engine in which high-pressure combustion gas is introduced and the piston is supported from the thrust side by the introduced high-temperature and high-pressure combustion gas, a reciprocating coating layer is formed on the surface of the second land of the piston. Dynamic engine.   The reciprocating engine according to claim 1, wherein the coating layer is made of a material having low thermal conductivity such as stainless steel or ceramic.   The reciprocating engine according to claim 1 or 2, wherein the coating layer is formed by a thermal spraying method.   The reciprocating engine according to any one of claims 1 to 3, wherein the coating layer is a multilayer coating layer composed of two or more layers.

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