JP2009127455A - Reciprocating engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reciprocating engine for reducing a friction loss between a piston and a cylinder and between a piston ring and a piston groove, reducing generation of blow-by gas, effectively cooling a piston upper body, and enhancing a combustion speed of mixed gas, by restraining a swing of the piston such as oscillation, rocking and lateral swinging of the piston, in engine operation. <P>SOLUTION: The reciprocating engine 1 has the piston 2 having the piston upper body 8 that has an upper surface 3 for receiving combustion/expansion gas pressure and also has a land section 7 provided with piston ring grooves 4, 5 and 6; a skirt section 9 formed below the piston upper body 8; and a piston boss section 11 for supporting a piston pin 10. The piston upper body 8 is formed eccentric to the anti-thrust side 13 relative to the center line 14 of the piston 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the explosion and expansion processes, the thrust is supported by the high pressure gas above the piston from the thrust side to the anti-thrust side against the thrust force (side pressure) acting on the piston due to the inclination of the connecting rod. The present invention relates to a reciprocating engine in which friction loss between a piston and a cylinder on the side is reduced.

  The present invention relates to a reciprocating engine in which a piston is supported by gas pressure in a top land on an outer peripheral surface of a piston upper body.

  Furthermore, the present invention relates to an improvement in a reciprocating engine incorporating a piston in which a top ring close to the upper surface of the piston is inclined and a top land is wide on the thrust side and narrowed on the anti-thrust side.

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

International Publication No. WO92 / 02722 Pamphlet

  In the technique described in Patent Document 1, the top ring of the piston is provided with an inclination. The top ring is disposed such that the distance from the upper surface of the piston is short on the anti-thrust side, long on the thrust side, and gradually longer from the anti-thrust side toward the thrust side. Therefore, the outer peripheral surface between the upper surface of the piston and the top ring, that is, the top land is wide on the thrust side and narrow on the anti-thrust side.

  The conventional reciprocating engine incorporating the piston having the above-described configuration is such that the high-pressure gas of the explosion / expansion above the piston mainly acts on the thrust side of the top land during the explosion and expansion strokes, and the thrust force acting on the piston ( The piston is supported from the thrust side to the anti-thrust side against the side pressure), and the sliding frictional resistance between the piston and the cylinder on the thrust side is reduced.

  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.

  Therefore, as in the prior art, the top land above the top ring is wide on the thrust side and narrow on the anti-thrust side, and the high pressure gas acts mainly on the thrust side of the top land to support the piston. However, the piston swinging phenomenon at the top dead center remains unchanged. That is, due to the presence of the gap, the piston swings and swings due to the moment load and thrust force during engine operation, particularly when reversing at top dead center. The piston upper body and skirt of the piston collide with the cylinder. For this reason, friction loss is generated between the piston and the cylinder, the piston ring and the cylinder, and the piston ring and the piston ring groove. In addition, blow-by gas is generated due to piston vibration.

  Therefore, the present invention suppresses piston vibration such as piston swinging, swinging, and rolling during engine operation, reducing friction loss between the piston and cylinder, piston ring and piston groove, and reducing generation of blow-by gas. In addition, the present invention aims to provide a reciprocating engine capable of effectively cooling the piston upper body and increasing the combustion speed of the mixed gas.

  Hereinafter, the top ring is referred to as a first piston ring.

  A reciprocating engine according to the present invention includes a piston upper body including an upper surface of a piston that receives combustion / expansion gas pressure and a land portion on which a piston ring is mounted, and a skirt formed at a lower portion of the piston upper body. In the piston, the piston upper body is formed eccentric to 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 maximum diameter portion of the skirt portion are aligned on a vertical line. In the state where the piston is housed in an upright posture in the cylinder, the outer peripheral surface of the piston upper body and the outer peripheral surface of the maximum diameter portion of the skirt portion are in contact with the inner surface of the cylinder on the anti-thrust side, and A gap is formed between the outer peripheral surface of the piston upper body and the inner surface of the cylinder on the thrust side, and the first device installed on the outer peripheral surface of the piston upper body. The stone ring is inclined and arranged so that the distance from the piston upper surface gradually increases from the anti-thrust side toward the thrust side, and the top land is formed wide on the thrust side and gradually narrowed toward the anti-thrust side. In the vicinity of top dead center or near top dead center, the high pressure gas above the piston is made difficult to go around the top land on the thrust side, and it acts mainly on the top land on the thrust side to support the piston from the thrust side. In addition, on the anti-thrust side, the outer peripheral surface and the skirt portion of the piston upper body are in contact with the cylinder inner surface to explode and expand the expansion stroke.

  According to the above configuration, the piston assembled in the cylinder is in the upright posture and on the side opposite to the thrust side, the outer peripheral surface of the piston upper body and the outer peripheral surface of the largest diameter portion of the skirt portion both abut against and contact the inner surface of the cylinder. ing. On the other hand, on the thrust side, a gap is formed between the outer peripheral surface of the piston upper body and the inner surface of the cylinder. Moreover, the top land of the piston upper body is wide on the thrust side and gradually narrows toward the anti-thrust side, and on the anti-thrust side, the outer peripheral surface of the piston upper body is in contact with the inner surface of the cylinder.

  For this reason, when the piston is located from the end of the compression stroke to the beginning of the explosion / expansion stroke, that is, at the top dead center or near the top dead center, the high-pressure gas above the piston acts on the top land over a wide area on the thrust side of the piston. The action on the top land on the anti-thrust side is very small.

  Therefore, the piston is mainly pushed from the thrust side, and no push-back from the anti-thrust side occurs, and the piston is supported by the gas pressure from the thrust side.

  Due to the inclination of the connecting rod on the thrust side, a side pressure (thrust force) acts on the piston that descends the combustion / expansion stroke. Reduced.

  Furthermore, because the piston is supported by the above gas pressure from the thrust side, the outer peripheral surface of the piston upper body and the outer peripheral surface of the skirt portion touch the inner surface of the cylinder and form a contact state on the anti-thrust side to maintain an upright posture. The piston can be prevented from swinging, swinging and colliding with the cylinder. For this reason, the friction loss between the piston and the piston ring can be reduced, and blow-by gas can be prevented from being blown out by vibration of the piston.

  Furthermore, since the piston upper body having an upper surface that receives high-temperature and high-pressure gas pressure is in contact with the cylinder on the anti-thrust side, the contact area with the cylinder is smaller than that with the conventional piston ring-only cylinder. Increases widely, the flow of heat from the piston to the cylinder is large, and the upper surface of the piston is effectively cooled.

  Therefore, abnormal combustion can be prevented, and the heat rise of the entire engine is low, so that the absorption efficiency can be secured well.

  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 and the cylinder, the piston ring and the piston groove, and the generation of blow-by gas 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.

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

  1 to 3 show an embodiment of a reciprocating engine of the present invention. FIG. 4 shows the piston 2 of the reciprocating engine 1 of this embodiment.

  The piston 2 includes a piston upper body 8 including a top surface of the piston that receives combustion / expansion gas pressure, that is, an upper surface 3 of the piston 2 and a land portion 7 having piston ring grooves 4, 5, 6. A skirt portion 9 formed on the lower side of the body 8 and a piston boss portion 11 that supports the piston pin 10 are provided.

  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.

  The piston ring grooves 4, 5, and 6 are a first piston ring groove 4, a second piston ring groove 5, and an oil ring groove 6 in order from the top surface 3 of the piston 2.

  A first piston ring 26 is placed in the first piston ring groove 4, a second piston ring 27 is placed in the second piston ring groove 5, and an oil ring 28 is placed in the oil ring groove 6.

  Of course, the first piston ring 26 is a top ring and the second piston ring 27 is a second ring.

  In the outer peripheral surface 16 of the piston upper body 8, the space between the upper surface 3 of the piston 2 and the first piston ring 4 is, of course, the top land 30, and between the first piston ring groove 4 and the second piston ring groove 5. Is the second land.

  In FIGS. 1 to 4, 12 indicates the thrust side, and 13 indicates the anti-thrust side. In particular, as shown in FIG. 4, 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.

  The piston 2 is formed in an upright posture in which the outer peripheral surface 16 of the piston upper body 8 and the outer peripheral surface 17 of the maximum diameter portion of the skirt portion 9 are aligned on a vertical line 18 on the anti-thrust side 13. .

  On the other hand, on the thrust side 12, the outer peripheral surface 16 of the piston upper body 8 is located on the inner side from the vertical line 21 passing through the outer peripheral surface 20 of the maximum diameter portion of the skirt portion 17, and there is a gap 19.

  Since the piston 2 is shaped as described above, as shown in FIG. 1, when it is assembled in the cylinder 23 and is in the upright posture, the outer peripheral surface 16 of the piston upper body 8 and the skirt portion 9 are on the anti-thrust side 13. And the outer peripheral surface 17 of the largest diameter portion are simultaneously in contact with the inner surface 24 of the cylinder 23.

  On the other hand, on the thrust side 12, a clearance (clearance) 25 exists between the outer peripheral surface 16 of the piston upper body 8 and the inner surface 24 of the cylinder 23.

  The piston 2 is provided with at least the first piston ring groove 4 inclined with respect to a plane perpendicular to the axis 29 of the piston 2.

  Further, the inclination of the first piston ring groove 4 is provided such that the distance A from the upper surface 3 of the piston 2 gradually increases as the distance A from the anti-thrust side 13 toward the thrust side 12 increases.

  For this reason, the top land 30 between the upper surface 3 of the piston 2 and the first piston ring groove 4 is narrow on the anti-thrust side 13, wide on the thrust side 12, and gradually from the anti-thrust side 13 toward the thrust side 12. It is getting wider.

  In the present embodiment, the second piston ring groove 5 is provided in parallel to the first piston ring groove 4.

  In FIGS. 1 and 2, the first piston ring 26, the second piston ring 27, and the oil ring 28 are mounted on the piston 2 as described above, and incorporated in the cylinder 23, thereby operating the engine. The inside state is shown.

  The piston 2 assembled in the cylinder 23 is in an upright posture and the outer peripheral surface 16 of the piston upper body 8 and the outer peripheral surface 17 of the maximum diameter portion of the skirt portion 9 are both attached to the inner surface 24 of the cylinder 23 on the anti-thrust side 13. You are in contact.

  On the other hand, on the thrust side 12, a gap 25 is formed between the outer peripheral surface 16 of the piston upper body 8 and the inner surface 24 of the cylinder 23.

  Moreover, the top land 30 of the piston upper body 8 is wide on the thrust side 12 and gradually narrows toward the anti-thrust side 13, and on the anti-thrust side 13, the outer peripheral surface 16 of the piston upper body 8 faces the inner surface 24 of the cylinder 23. It is in contact.

  For this reason, when the piston 2 is positioned from the end of the compression stroke to the beginning of the expansion and expansion stroke, that is, at the top dead center or near the top dead center, the space 31 between the inner surface 24 of the cylinder 23 and the top land 30 of the piston 2 is The top land 30 which is large on the thrust side 12 and sufficiently communicates with the combustion / expansion gas pressure 33 of the combustion chamber 32 above the piston 2 and which receives the gas pressure is wide.

  On the other hand, the space 31 is closed on the anti-thrust side 13. For this reason, the combustion / expansion gas pressure 33 wraps around the top land 30 of the piston 2 on the anti-thrust side 13. Absent.

  Therefore, the combustion / expansion gas pressure 33 acts on the top land 30 on the thrust side 12 of the piston 2 in a wide area, while the action on the top land 30 is very small on the anti-thrust side 13.

  Therefore, the piston 2 is mainly pushed from the thrust side 12 toward the anti-thrust side 13, and the pushing back force from the anti-thrust side 13 is very small. In the anti-thrust side 13, the outer peripheral surface 16 of the piston upper body 8 and the outer peripheral surface 17 of the largest diameter portion of the skirt portion 9 are in contact with the inner surface 24 of the cylinder 23. The combustion expansion stroke is lowered.

  When the piston 2 located at the top dead center or in the vicinity of the top dead center is viewed from above, the outer peripheral surface 16 of the piston upper body 8 on the anti-thrust side 13 has an arc shape as shown in FIG. An arcuate gap 25 exists between the outer peripheral surface 16 and the inner surface 24 of the cylinder 23 on the thrust side 12 in contact with the inner surface 24.

  When the compressed gas pressure and the combustion / expansion gas pressure 33 act on the upper surface 3 of the piston 2 in the above state, the gas pressure 33 mainly acts on the top land 30 on the thrust side 12, but the top on the anti-thrust side 13. You can clearly see that the land 30 cannot be wrapped around.

  According to the reciprocating engine 1 of the present embodiment as described above, the piston 2 is pressed against the inner surface 24 of the cylinder 23 on the thrust side 12 by the inclination of the connecting rod 22 toward the thrust side 12 during the combustion / expansion stroke. Even if a side pressure (thrust force) F acting on the piston 2 is lowered, the piston 2 is supported by the gas pressure in the piston upper body 8 on the thrust side 12 and is thus lowered. Friction loss is reduced. Further, the piston 2 is pushed from the thrust side 12 to the anti-thrust side 13 by gas pressure, and the outer peripheral surface 16 of the piston upper body 8 and the outer peripheral surface 17 of the skirt portion 9 are brought into contact with the inner surface 24 of the cylinder 23 on the anti-thrust side 13. Contact and keep upright. For this reason, the piston 2 can be prevented from sideways swinging, swinging and colliding with the cylinder. Therefore, the friction loss between the piston 2 and the piston rings 4 and 5 can be reduced, and the blow-by gas can be prevented from being blown out by the vibration of the piston 2.

  Further, since the piston upper body 8 having the upper surface 3 that receives high-temperature and high-pressure gas pressure is in contact with the inner surface 24 of the cylinder 23 on the anti-thrust side 13, the piston 2 is in contact with the cylinder with only the conventional piston ring. As compared with the above, the contact area of the inner surface 24 of the cylinder 23 increases widely, the flow of heat from the piston 2 to the cylinder 23 increases, and the upper surface 3 of the piston 2 is effectively cooled.

  Therefore, abnormal combustion can be prevented, and the heat rise of the entire engine is low, so that the absorption efficiency can be secured well.

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. FIG. 2 is a cross sectional explanatory view of the example shown in FIG. 1. It is explanatory drawing of the piston of the example shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reciprocating engine 2 Piston 8 Piston upper body 9 Skirt part 23 Cylinder 26 1st piston ring 27 2nd piston ring

Claims (1)

  In a piston comprising a piston upper body comprising an upper surface of a piston that receives combustion / expansion gas pressure and a land portion to which a piston ring is attached, and a skirt formed at the lower portion of the piston upper body, the piston upper body is It is formed eccentrically 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 largest diameter portion of the skirt are aligned on the vertical 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 maximum diameter portion of the skirt portion are in contact with the inner surface of the cylinder on the non-thrust side, and the outer periphery of the piston upper body is on the thrust side. A gap is formed between the surface and the inner surface of the cylinder, and the first piston ring disposed on the outer peripheral surface of the piston upper body is a piston The top land is inclined so that the distance from the surface gradually increases from the anti-thrust side toward the thrust side, and the top land is formed wide on the thrust side and gradually narrows toward the anti-thrust side. Further, in the vicinity of the top dead center, the high pressure gas above the piston is made difficult to go around the top land on the anti-thrust side, and acts mainly on the top land on the thrust side to support the piston from the thrust side, and A reciprocating engine in which the outer peripheral surface of the piston upper body and the skirt portion are in contact with the inner surface of the cylinder on the non-thrust side and the explosion and expansion strokes are lowered.

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