JP2011007076A - Reciprocating engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reciprocating engine for reducing a friction loss between a piston and a cylinder inner surface.SOLUTION: In this reciprocating engine 1, a second piston ring 27 forming an annular gas chamber 31 is downward slantingly arranged toward the thrust side 12 from the anti-thrust side 13, and the annular gas chamber 31 is gradually widely formed toward the thrust side 12 from the anti-thrust side 13, and in an upper part 33 on the thrust side 12 of an inner surface 24 of a cylinder 23, a recessed place 34 is formed to be formed longer in the circumferential direction 46 of the cylinder 23 than the direction 45 along the axis 44 of the cylinder 23, and when a piston 2 is positioned in the vicinity of the top dead center, a combustion chamber 37 above the piston 2 communicates with the annular gas chamber 31 formed in the piston 2 via a recessed space 36 of the recessed place 34.

Description

  In the present invention, during operation, the piston is supported by gas pressure from the thrust side to the anti-thrust side, and on the anti-thrust side, the piston is attached to the cylinder wall, and the piston swings, swings, swings, etc. The present invention relates to a reciprocating engine which is lowered so as not to be shaken, thereby reducing friction loss between a piston and a cylinder and friction loss between a piston and a piston ring.

  Of course, the present invention relates to a reciprocating engine that can be used as a four-cycle gasoline engine, a two-cycle gasoline engine, or a diesel engine.

  As a technique for reducing the friction loss between the piston and the cylinder on the thrust side due to the thrust force acting on the piston, International Publication No. WO92 / 02722, JP-A-4-347352, JP-A-5-26106, Patent No. No. 2988010, International Publication No. 2008/047453 (see Patent Documents 1 to 5), and the like. In these techniques, a gas chamber is formed between the piston rings for compression provided in the piston upper body, that is, in the second land portion, and in the initial stage of the expansion stroke of the engine operation, the high pressure gas above the piston is placed in the gas chamber. The piston is supported against the thrust force generated by the inclination of the connecting rod by the introduced gas pressure, and the friction loss between the piston and the cylinder inner surface is reduced.

International Publication No. WO92 / 02722 Pamphlet JP-A-4-347352 Japanese Patent Laid-Open No. 5-26106 Japanese Patent No. 2988010 International Publication No. 2008/047453 A1

  By the way, the diameter of the piston upper body of the reciprocating engine is smaller than the maximum diameter portion of the skirt portion, and the entire piston is trapezoidal. That is, the piston upper body is incorporated in the cylinder with a clearance (clearance) with respect to the cylinder inner diameter. That is, there is always a gap between the piston upper body of the piston and the cylinder inner surface on both the thrust side and the anti-thrust side. For this reason, as in the prior art, a gas chamber is formed broadly on the thrust side between the piston rings for compression, that is, in the second land portion. Even if high-pressure gas is introduced and the piston is supported by the introduced gas pressure, the high-pressure gas circulates on the side opposite to the piston thrust and is pushed back, so that a sufficient gas pressure support effect cannot be obtained for the piston. In addition, piston runout or the like occurs.

  The friction loss between the piston and the cylinder cannot be sufficiently reduced. International Publication No. 2008/047453 can eliminate the above-mentioned defects, but there is no device such as a shape in the gas passage for introducing the combustion high-pressure gas above the piston into the gas chamber formed in the piston, and the high-pressure gas Inflow is not effective.

  Therefore, the present invention eliminates the above-mentioned deficiencies in the prior art, effectively flows the combustion high-pressure gas above the piston into the gas chamber formed in the piston, and counteracts the piston side pressure with a sufficiently introduced gas pressure. Thus, the piston is lowered in a state of being sufficiently floated (or supported) from the inner surface of the cylinder, thereby providing a reciprocating engine in which friction loss between the piston and the inner surface of the cylinder is reduced.

  A reciprocating engine of the present invention is a piston provided with a piston upper body comprising a crown portion for receiving combustion gas pressure and a land portion on which a piston ring is mounted, and a skirt portion formed on the lower side of the piston upper body. The piston upper body is eccentrically formed on the anti-thrust side with respect to the piston center line, and on the anti-thrust side, the outer peripheral surface of the piston upper body and the outer peripheral surface of the skirt portion are formed in a straight line, and the piston is attached to the cylinder. In an upright position, the outer peripheral surface of the piston upper body and the outer peripheral surface of the skirt portion are in contact with the inner surface of the cylinder on the anti-thrust side, and the outer peripheral surface of the piston upper body and the cylinder on the thrust side. Between the first piston ring and the second piston ring attached to the outer peripheral surface of the piston upper body with a gap between the inner surface An annular gas chamber is formed in the second land portion, and the second piston ring forming the annular gas chamber is inclined downward from the anti-thrust side toward the thrust side, and the annular gas chamber is formed from the anti-thrust side. A recess that is formed to be wider in the circumferential direction of the cylinder than in the direction along the axis of the cylinder is formed in the upper portion on the thrust side of the inner surface of the cylinder. When the piston is located in the vicinity of the top dead center, the annular gas chamber formed in the piston and the combustion chamber above the piston communicates with each other through the recessed space of the recess. In the reciprocating engine of the present invention, the recess is formed longer in the circumferential direction of the cylinder than in the direction along the axis of the cylinder, and bends upward or downward at the center, and both sides thereof Is formed in an upward slope or a downward slope in the circumferential direction, and is formed in a V shape or a square shape as a whole so that the recessed spaces are connected together as a whole.

  According to the above configuration, when the piston is in the vicinity of the top dead center and the first piston ring passes through the recess of the gas passage, the combustion gas pressure above the piston acts on the upper surface of the piston. On the thrust side, combustion gas flows into the annular gas chamber of the piston through a gap between the outer peripheral surface of the piston upper body and the inner surface of the cylinder and a recess formed in the inner surface of the cylinder. At this time, the recess is long in the circumferential direction of the cylinder, bends upward or downward at the center, and is formed so that both sides thereof are inclined upward or downward toward the cylinder circumferential direction, and Since the recessed space is formed as a whole, the first piston ring is also in contact with and supported by the inner surface of the cylinder even in this recessed portion, so that a wide gas passage, that is, the recessed space is secured and the flow becomes easy. Therefore, the combustion gas above the piston is satisfactorily introduced into the annular gas chamber of the piston, and the piston is pushed from the thrust side to the anti-thrust side by this introduced gas pressure, so that the cylinder inner surface is sufficiently floated.

On the other hand, since the piston is in contact with the inner surface of the cylinder on the anti-thrust side, the combustion gas pressure cannot go around to the outer surface of the piston on the anti-thrust side. For this reason, the piston does not push back from the anti-thrust side to the thrust side, and the explosion stroke is lowered in a state where the gas pressure on the piston is supported by the gas pressure on the thrust side, that is, the piston float is not attenuated.
From the above state, even if the piston side pressure and the moment force due to the frictional resistance between the piston pin and the piston act on the thrust side from the above state, the piston is supported by the gas pressure and descends.

  For this reason, it is possible to sufficiently reduce the friction loss between the piston and the cylinder inner surface.

  Further, at the initial stage of the expansion stroke, when the piston is located at or near the top dead center and the first piston ring of the piston passes through the plurality of recesses, the gas pressure during combustion above the piston is changed to the annular gas chamber of the piston. Therefore, the combustion gas above the piston flows and is disturbed, the combustion speed is increased, and the combustion time is shortened.

  According to the present invention, during engine operation, the lateral movement of the piston, such as the swinging and swinging of the piston, is suppressed, the friction loss between the piston ring and the cylinder, the piston ring and the piston groove, and the blow-by gas generation are reduced. Further, it is possible to provide a reciprocating engine capable of effectively cooling the piston upper body and increasing the combustion speed of the mixed gas.

It is longitudinal section explanatory drawing of the example of embodiment of this invention. It is operation | movement explanatory drawing of the example shown in FIG. It is explanatory drawing of the inner surface of a cylinder. It is operation | movement explanatory drawing of the example shown in FIG. It is operation | movement explanatory drawing of the example which changed the shape of the recess of a cylinder inner surface. It is a side view of the piston of the example shown in FIG. It is a side view of the piston which changed arrangement of the 1st piston ring.

  Embodiments of the present invention will be described below with reference to examples shown in the drawings.

  1 to 9 show an embodiment of the reciprocating engine of the present invention.

  6 and 7 show the piston 2 of the reciprocating engine 1 of this embodiment. The piston 2 includes a piston upper body 8 composed of a crown portion 3 for receiving combustion pressure and a land portion 7 having piston ring grooves 4, 5, 6, and a skirt portion 9 formed on the lower side of the piston upper body 8. And a pin boss portion 11 for supporting the piston pin 10. The land portion 7 also refers to the outer peripheral surface 16 of the piston upper body 8. Hereinafter, the land portion 7 is referred to as the outer peripheral surface 16 of the piston upper body 8. In the piston 2, 12 indicates the thrust side, and 13 indicates the anti-thrust side.

  The piston 2 is formed such that the piston upper body 8 is eccentric to the anti-thrust side 13 with respect to the center line 14 of the piston 2. Reference numeral 15 denotes a center line of the piston upper body 8. As shown in FIGS. 6 and 7, the piston 2 is in an upright posture, and on the anti-thrust side 13, the outer peripheral surface 16 of the piston upper body 8 and the outer peripheral surface 17 of the skirt portion 9 are aligned on a straight line 18. Is formed.

  On the other hand, on the thrust side 12, the outer peripheral surface 19 of the piston upper body 8 is located inside a straight line 21 passing through the outer peripheral surface 20 of the skirt portion 17, and there is a gap 22.

  Since the piston 2 is shaped as described above, as shown in FIGS. 1 and 2, when the piston 2 is incorporated in the cylinder 23 and is in the upright posture, the outer circumferential surface 16 of the piston upper body 8 and the skirt are on the anti-thrust side 13. The outer peripheral surface 17 of the portion 9 is in contact with the inner surface 24 of the cylinder 23 together. On the other hand, on the thrust side 12, a clearance (clearance) 25 exists between the outer peripheral surface 19 of the piston upper body 8 and the inner surface 24 of the cylinder 23.

  A piston ring for compression is mounted in the piston ring groove 4 of the piston upper body 8. That is, the first piston ring 26 is attached to the piston ring groove 4 closest to the crown portion 3, and the second piston ring 27 is attached to the piston ring groove 5 closest to the crown portion 3. The first piston ring is a top ring, and the second piston ring is a second ring. An oil scraper ring 28 is attached to the lowermost ring groove 6.

  As shown in FIG. 6, in the piston 2, the piston ring groove 4 in which the first piston ring 26 is mounted and the piston ring groove 5 in which the second piston ring 27 is mounted are orthogonal to the axis 29 of the piston 2. Inclined with respect to the surface to be formed. The piston ring groove 4 and the piston ring groove 5 are provided so as to incline toward the opposite side with respect to each other, and are provided so as to gradually separate from the anti-thrust side 13 toward the thrust side 12.

  Therefore, the second land portion 30 surrounded by the piston ring groove 4 and the piston ring groove 5 is wide on the thrust side 12 and narrow on the anti-thrust side 13.

  Further, as shown in FIG. 7, the piston ring groove 4 is formed in parallel with the piston upper surface, that is, the crown portion 3, and the piston ring groove 5 is gradually inclined downward toward the thrust side 12. The piston ring groove 4 and the piston ring 5 may be provided so as to gradually separate from the thrust side 13 toward the thrust side 12. Also in the piston 2 shown in FIG. 7, the second land portion 30 surrounded by the first piston ring groove 4 and the second piston ring groove is wide on the thrust side 12 and narrow on the anti-thrust side 13.

  1 and 2, the piston 2 in which the first piston ring 26, the second piston ring 27, and the oil scraper ring 28 are mounted in the piston ring grooves 4, 5, and 6 is incorporated in the cylinder 23. In this state, the engine is operating in an upright position.

  An annular gas chamber 31 is formed in the piston 2 by being surrounded by a second land portion 30 formed between the first piston ring 26 and the second piston ring 27 and the inner surface 24 of the cylinder 23. The annular gas chamber 31 is wide on the thrust side 12 and gradually narrows toward the anti-thrust side 13. This is to push the piston 2 widely and strongly from the thrust side 12 by the gas pressure 39 flowing into the annular gas chamber 31 and to reduce the gas flow to the anti-thrust side 13 to reduce the pushing back.

  Next, the cylinder 23 is provided with a recess 34 in the upper portion 33 of the inner surface 24 on the thrust side 12. The recess 34 is formed in a hollow shape from the cylinder inner surface 24. Although described later, the recess 34 serves as a gas pressure passage. The position of the recess 34 is determined such that the first piston ring 26 of the piston 2 is passing over the recess 34 when the piston 2 is at or near the top dead center. Thus, when the piston 2 is in the vicinity of the top dead center and the first piston ring 26 is passing over the recess 34, the recessed space 36 of the recess 34 and the outer peripheral surface of the first piston ring 26 are The combustion chamber 37 above the piston 2 and the annular gas chamber 31 of the piston 2 communicate with each other, and the high pressure gas pressure 38 above the piston 2 flows into the annular gas chamber 31 as indicated by an arrow 41. It is supposed to be. The recess 34 is also provided so as not to be connected to the second piston ring 27 when the piston 2 is located at the top dead center. This is to prevent the high pressure gas 38 in the combustion chamber 37 from blowing down from the piston 2. During engine operation, particularly when the piston 2 is located at or near the top dead center, when the first piston ring 26 passes over the recess 34 from the end of the compression stroke to the beginning of the expansion stroke, the piston 2 The high-pressure gas 38 in the combustion chamber 37 above the gas flows into the annular gas chamber 31 of the piston 2 through the recess 34. At the same time, the piston 2 is supported by the inflowing high-pressure gas 39 in the annular gas chamber 31 in the piston upper body 8 and is pushed from the thrust side 12 toward the anti-thrust side 13. The piston 2 holds the gas pressure 39 acting as described above in the annular gas chamber 31, and the outer peripheral surface 16 on the anti-thrust side 13 of the piston upper body 8 and the outer peripheral surface 17 of the skirt portion 9 are the inner surfaces of the cylinder 23. In the state in contact with 24, it descends in the expansion stroke.

  By the way, as shown in FIGS. 3, 4, and 5, the recess 34 of the inner surface 24 of the cylinder 23 has a circumferential direction 46 of the cylinder 23 rather than a direction 45 along the axis 44 of the cylinder 23. It is formed long. As shown in FIGS. 3 and 4, the shape of the recess 34 is formed by bending upward at the central portion 42 when viewed from the front, and its both side portions 43 and 43 are inclined upward. As a V shape. Further, as shown in FIG. 5, it may be bent downward at the central portion 42, and both side portions 43, 43 may be formed so as to be inclined downward and formed in a letter-like shape as a whole.

  Of course, the recess 34 is connected to the both sides 43 and 43 from the central portion 42 by the recess space 36.

  When the first piston ring 26 (top ring) passes through the recess 34 as described above, the recess 34 is long in the circumferential direction as shown in FIGS. The piston ring 26 is supported by being in contact with the inner surface 24 of the cylinder 23, and the gas passage, that is, the recessed space 36 is long and easily flows with one recess 34. For this reason, the explosion combustion gas pressure on the upper surface of the piston is satisfactorily introduced into the annular gas chamber 31 of the piston 2.

  Due to this gas pressure introduced into the annular gas chamber 31, the piston 2 is in a state of being floated from the inner surface 24 of the cylinder 23 on the thrust side 12, and the explosion stroke is lowered. Therefore, the friction loss between the piston 2 and the inner surface 24 of the cylinder can be sufficiently reduced. On the other hand, since the piston 2 is in contact with the inner surface 24 of the cylinder 23 on the anti-thrust side 13, the intrusion of combustion gas into the outer peripheral surface of the piston 2 on the anti-thrust side 13 is prevented. There is no pushback due to the gas pressure toward the thrust side 12. Therefore, the piston 2 lowers the explosion stroke while the gas pressure is supported from the thrust side 12 to the piston 2, that is, the piston 2 is not lifted off from the cylinder inner surface 24.

  Therefore, the frictional resistance between the piston 2 and the cylinder inner surface 24 is reduced.

DESCRIPTION OF SYMBOLS 1 Reciprocating engine 2 Piston 3 Crown part 4 1st piston ring groove 5 2nd piston ring groove 6 2nd piston ring groove 7 Land part 8 Piston upper body 9 Skirt part 10 Piston pin 11 Pin boss part 12 Thrust side 13 Anti-thrust side 14 piston center line 15 piston upper body center line 16 outer peripheral surface of piston upper body 15 outer peripheral surface of skirt portion 18 straight line 19 outer peripheral surface of thrust side piston upper body 20 outer peripheral surface of thrust side skirt portion 21 thrust side straight line 22 Clearance 23 Cylinder 24 Inner surface 25 Clearance (clearance)
26 First Piston Ring 27 Second Piston Ring 28 Oil Scribing Ring 29 Piston Axis 30 Second Land Part 31 Annular Gas Chamber 33 Upper Part 34 Recess 35 Circumferential Direction 36 Recessed Space 37 Combustion Chamber 38 High Pressure Gas 39 Gas Pressure 41 Arrow 42 Center part 43 Both sides 44 Cylinder axis 45 Direction along axis 44 46 Circumferential direction

Claims (2)

  In a piston comprising a piston upper body comprising a crown part for receiving combustion gas pressure and a land part equipped with a piston ring, and a skirt formed on the lower side of the piston upper body, the piston upper body is located at the center of the piston. In the state where the outer peripheral surface of the piston upper body and the outer peripheral surface of the skirt portion are formed in a straight line on the anti-thrust side with respect to the line, and the piston is placed in an upright posture on the cylinder. The outer peripheral surface of the piston upper body and the outer peripheral surface of the skirt are brought into contact with the inner surface of the cylinder on the non-thrust side, and a gap is generated between the outer peripheral surface of the piston upper body and the inner surface of the cylinder on the thrust side. An annular gas chamber is formed in the second land portion between the first piston ring and the second piston ring mounted on the outer peripheral surface of the piston upper body. The second piston ring forming the annular gas chamber is provided to be inclined downward from the anti-thrust side toward the thrust side, and the annular gas chamber is gradually formed from the anti-thrust side toward the thrust side. A recess formed longer in the circumferential direction of the cylinder than in the direction along the cylinder axis is formed in the upper part of the cylinder on the thrust side, and the piston is positioned near the top dead center. A reciprocating engine in which the annular gas chamber formed in the piston and the combustion chamber above the piston communicates with each other through the recessed space of the recess.   The recess is formed longer in the circumferential direction of the cylinder than in the direction along the axis of the cylinder, and bends upward or downward at the center, and both sides thereof are inclined upward in the circumferential direction. The reciprocating engine according to claim 1, wherein the reciprocating engine is formed in a downward slope and formed in a V shape or a U shape as a whole, and the recessed spaces are connected together as a whole.

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