JP2010150994A - Oil supply system and piston of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston capable of improving cooling and lubrication property of a skirt part having a significant sliding load with a cylinder wall part. <P>SOLUTION: The piston of the internal combustion engine includes an oil-ring groove 29 arranged at an outer periphery of a crown part 20 and a communication passages 30. 31 for communicating inside of the crown part and the oil-ring groove at a first skirt part 21 (a thrust side) and a second skirt part 22 (an anti-thrust side) of the oil-ring groove. A projection part 34 is arranged in a crown part back surface 20c. At moving positions at a top dead-center side and a bottom dead-center side of the piston, injected oil is forcibly supplied from the first guide groove 35 to the oil-ring groove 29 on the thrust side via a first slit 32 and the like. At a middle moving position of the piston, the injected oil is forcibly supplied from the second guide groove 36 to the oil-ring groove on the anti-thrust side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an oil supply system that efficiently supplies, for example, oil injected from an oil jet to the inside of a piston to a thrust side and an anti-thrust side of a piston skirt, and a piston of an internal combustion engine.

  Various oil supply devices that forcibly supply oil to a piston of an internal combustion engine to cool and lubricate the piston have been conventionally provided, and one of them is described in Patent Document 1 below. .

  Briefly, oil is sprayed from an oil jet to one end side in the radial direction of the lower surface (ceiling surface) opposite to the upper surface of the crown portion of the piston, and the other one in the radial direction from the one end side to the ceiling surface. A rib extending toward the end is formed.

  This rib is formed so that the protruding direction height in the piston axial direction gradually increases as it goes from the one end side to the other end side, thereby comparing with the case where the protruding height in the axial direction of the piston is the same, The height of the lower end edge of the rib is lowered from the one end side toward the other end side.

For this reason, the oil jetted from the oil jet to the one end side flows well to the other end side through the rib while being prevented from dropping in the oil reservoir.
JP 2004-270489 A

  However, in the conventional oil supply apparatus, the oil injected to the one end side is only supplied to the other end side via the rib. Therefore, there is a possibility that the supply of oil to a portion that needs to be lubricated or cooled is insufficient.

  The invention according to claim 1 relates to an oil supply system, and in particular, an oil supply means for changing the oil supply amount on the thrust side and the anti-thrust side according to the movement position of the piston during the cycle stroke of the internal combustion engine is provided. It is characterized by that.

  According to a third aspect of the present invention, there is provided a piston for an internal combustion engine, wherein oil is guided to a thrust side and an anti-thrust side on a back surface side of the crown portion according to a moving position of the piston during a cycle stroke of the internal combustion engine. It is characterized by providing a convex portion for guiding.

  According to the present invention, for example, when the piston moves to the top dead center side or the bottom dead center side, for example, the oil injected from the oil jet is on the piston thrust side centered on the top of the convex portion in the crown. The fuel is injected toward the inclined guide surface or the inclined guide surface on the anti-thrust side, and directly flows on one of the wall surfaces and flows into the oil ring groove through the communication path. As a result, the sliding friction resistance between the oil ring on the thrust side or the anti-thrust side of the piston skirt that is particularly heavy and the inner wall surface of the cylinder is reduced, and the cooling effect on the thrust side and the anti-thrust side is improved.

  Hereinafter, an embodiment in which an oil supply system according to the present invention is applied to a piston of a so-called four-cycle internal combustion engine will be described in detail with reference to the drawings.

[First embodiment]
That is, in the internal combustion engine 1, as shown in FIG. 8, a crankshaft 5 is rotatably supported by a bearing outside the figure in a crank chamber 4 separated by a crankcase 3 of a cylinder block 2. A piston 8 connected to the crankshaft 5 via a connecting rod 7 is slidably provided inside a cylindrical cylinder wall 6 formed in the upper part of the crankcase 3.

  A water jacket 9 through which cooling water circulates is formed in the wall of the cylinder wall 6, and an oil pump (not shown) is provided inside the partition wall 10 between the crankcase 3 and the cylinder wall 6. A main oil gallery 11 is formed for supplying the discharged oil (lubricating oil) to each sliding portion of each engine.

  An oil jet 12 for supplying oil for cooling and lubrication between the inner peripheral surface of the cylinder wall 6 and the piston 8 is attached to the lower part of the partition wall 10 by a bolt 13 via a bracket 16. ing.

  The oil jet 12 includes a body 14 formed of a metal material, and a nozzle 15 having a base end portion fixed to the lower end portion of the peripheral wall of the body 14 and a tip portion bent upward. . The oil supplied from the main oil gallery 11 into the body 14 is injected from the nozzle 15 into the piston 8 through a plunger (not shown) that slides inside the body 14. Yes.

  As shown in FIGS. 1 to 6, the piston 8 is formed integrally with an aluminum alloy material in a substantially cylindrical shape, and has a relatively thick disc-shaped crown portion 20 that receives the combustion pressure in the combustion chamber 17. The pair of first and second skirt portions 21 and 22 that are integrally formed at the lower portion of the crown portion 20 and are in sliding contact with the inner peripheral surface 6a of the cylinder wall 6 are formed integrally at the lower portion of the crown portion 20. The apron portions 23 and 24 formed at approximately 90 ° positions in the circumferential direction of the skirt portions 21 and 22 and formed at substantially the center of the apron portions 23 and 24, rotate both ends of the piston pin 25. And pin bosses 26 and 27 having a pair of pin holes 26a and 27a that are freely supported.

  In the crown portion 20, a top ring groove 27, a second ring groove 28, and an oil ring groove 29 are formed on the outer peripheral surface from above through respective land portions.

  The top ring groove 27 and the second ring groove 28 hold a top ring and a second ring (not shown), which seal the combustion gas generated in the combustion chamber 17 including the space between the inner peripheral surface of the cylinder wall 6. Thus, output reduction due to gas blow-off is prevented.

  On the other hand, the oil ring groove 29 holds an oil ring (not shown) and prevents the oil adhering to the inner peripheral surface of the cylinder wall 6 from flowing into the combustion chamber 17 so as to prevent the combustion chamber from below the cylinder wall 6. 17 prevents the oil from rising and burning.

  Both the skirt portions 21 and 22 are formed in a comparatively thin arc shape, and when the piston 8 reciprocates up and down, the skirt portions 21 and 22 are in sliding contact with the inner peripheral surface 6a of the cylinder wall 6 so that the piston 8 moves smoothly. The first skirt portion 21 on one side is brought into pressure contact with the inner peripheral surface of the cylinder wall 6 by the combustion pressure and becomes a thrust side on which a large load acts, and the second skirt portion 22 on the other side rises the piston 8 It is on the anti-thrust side that is in pressure contact with the inner peripheral surface of the cylinder wall 6 during movement (top dead center side).

  Both the pin boss portions 26 and 27 transmit the combustion pressure received by the crown portion 20 to the piston pin 25 through the respective pin holes 26a and 27a, and further to the connecting rod 7 from here.

  In addition, as shown in FIGS. 3 and 4, a portion of the oil ring groove 29 where the skirt portions 21 and 22 are located is a communication path that connects the oil ring groove 29 and the inside of the piston 8. A certain pair of left and right communication holes 30, 30, 31, 31 are formed penetrating along the radial direction. The communication holes 30, 30, 31, 31 are disposed within the circumferential range of the skirt portions 21, 22, and are formed at positions separated from each other in the circumferential direction.

  Further, as shown in FIGS. 3 and 4, first and second slits 32 and 33 are formed between the communication holes 30, 30, 31 and 31, respectively. Are connected to the respective communication holes 30, 30, 31, 31.

  Then, on the back surface (ceiling surface) 20c side of the crown portion 20 opposite to the upper surface 20a, the oil injected from the nozzle 15 of the oil jet 12 according to the reciprocating position of the piston 8 is first skirt portion 21. Guide means for guiding to the side and the second skirt portion 22 side is provided.

  As shown in FIGS. 1, 5 and 6, the guide means has a convex portion 34 projecting from the first skirt portion 21 side, and a downward slope from the top 34 a of the convex portion 34 toward the first slit 32. The first guide groove 35, which is a first guide surface formed in a shape, and the second guide groove 36, which is a second guide surface formed so as to be inclined downward from the top toward the second slit 33, are mainly configured. ing.

  As shown in FIG. 1, the convex portion 34 is arranged close to the first skirt portion 21, and is disposed at both ends in the circumferential direction of the first skirt portion 21, that is, opposite end portions of the two apron portions 23 and 24. It is formed in an arc shape to the side, and the cross section is formed in an approximately arc shape with a comparatively gentle curve.

  The first guide groove 35 is further formed in a concave shape from the arcuate outer peripheral edge 34a of the convex portion 34. The first guide groove 35 is formed in an arc shape along the first slit 32 like the convex portion 34, and is substantially at the bottom. It communicates with the first slit 32 in the vicinity.

  On the other hand, the second guide groove 36 extends from the inner end edge 34b of the convex portion 34 between the pin bosses 25 and 26 toward the second skirt portion 22 as shown in FIGS. The raised portion 37 is formed at a substantially central position in the width direction, and has a substantially V-shaped concave shape (saddle shape) with a gentle cross section. Further, the second guide groove 36 extends from a substantially central position in the longitudinal direction of the inner end edge 34a of the convex portion 34 toward the second skirt portion 22, and a terminal edge 36a which is the lowest position is provided in the second guide groove 36. It is gently connected to the back surface 20c and oriented in the direction of the second slit 33. That is, the end edge 36a of the second guide groove 36 is smoothly connected to the back surface 20c between the pin bosses 25 and 26 to supply oil widely on the back surface 20c, and also through the second slit 33 to the second skirt. It is formed so as to guide into the oil ring groove 29 on the part 22 side.

  The convex portion 34 is formed at the top dead center side and the bottom dead center side of the piston 8 and the injection direction (extension direction) of the nozzle 15 of the oil jet 12 is the convex side surface on the first guide groove 35 side. The intermediate movement position between the top dead center side and the bottom dead center side of the piston 8 is set to be the convex side surface direction on the first guide groove 36 side.

  Therefore, according to this embodiment, during the four-stroke stroke (intake-compression-combustion-exhaust) after the start of the internal combustion engine, the piston 8 is at the top dead center side and the bottom dead center side, that is, near and above the top dead center. Between the dead center and between the vicinity of the bottom dead center and the bottom dead center, the oil jetted from the oil jet 12 is on the first guide groove 35 side of the convex portion 34 as shown by the arrow in FIG. 7A. It collides with the convex side surface of the first, and flows into the first guide groove 35 intensively and is collected. Therefore, the periphery of the first skirt portion 21 is effectively cooled.

  Thereafter, the oil is supplied into the oil ring groove 29 through the first slit 32 while being guided by the bottom surface of the first guide groove 35. For this reason, since oil is forcibly provided between the oil ring on the first skirt portion 21 side and the inner peripheral surface of the cylinder wall 6, the sliding portion of the cylinder wall 6 with the inner peripheral surface 6a Lubrication performance is improved.

  The first skirt portion 21 receives a large combustion pressure acting on the crown upper surface 20a during the combustion stroke, and the outer peripheral surface is strongly pressed against the inner peripheral surface of the cylinder wall 6 to increase the load. Improvement of this makes it possible to slide the piston 8 smoothly.

  In addition, the convex portion 34 and the first guide groove 35 are formed in the vicinity of the first skirt portion 21 and supply oil from the oil jet 12 to the first skirt portion 21 side immediately. The first skirt portion 21 can be cooled and lubricated more quickly and effectively.

  Moreover, since the said convex part 34 and the 1st guide groove 35 are formed in circular arc shape along the circumferential direction of the 1st slit 32, the oil injected to the convex part 34 is each circular arc shape. The oil is intensively supplied into the oil ring groove 29 from the entire first slit 32 while expanding along. Therefore, a large amount of oil can be supplied in the circumferential direction of the oil ring, that is, in the circumferential direction of the first skirt portion 21, so that the cooling and lubricity of the sliding portion are further improved.

  On the other hand, at the intermediate movement position from the vicinity of the top dead center to the vicinity of the bottom dead center of the piston 8, the oil jetted from the oil jet 12 is, as shown by the arrow in FIG. It collides with the convex side surface on the 36 side and effectively cools the periphery of the second skirt portion 22 from the second guide groove 36.

  Thereafter, the oil is supplied into the oil ring groove 29 through the second slit 33 while being guided along the bottom surface of the second guide groove 35. For this reason, since it is forcibly supplied between the oil ring on the second skirt portion 22 side and the inner peripheral surface of the cylinder wall 6, the lubrication performance of the sliding portion on the second skirt portion 22 side where a large load is applied. Will improve.

  In addition, the oil that has flowed while being guided by the second guide groove 35 flows to almost the entire back surface 20c of the crown portion 20 and cools the entire crown portion 20, so that the cooling effect is increased.

  In addition, the oil guided from the convex portion 34 to the back surface 20c through the second guide groove 36 also drops onto the upper surface of the piston pin 25, and the piston pin 25 has both ends and inner peripheries of the pin holes 26a and 27a. Since the piston pin 25 is rotatably supported by the pin holes 26a and 27a, the lubricity between the two is also improved.

  Further, the presence of the convex portion 34 and the built-up portion 37 increases the rigidity of the crown portion 20 and improves durability against combustion pressure and the like.

  As described above, according to the reciprocating position of the piston 8, the oil injected from the oil jet 12 can effectively cool and lubricate the first skirt portion 21 having a large load, and the entire crown portion 20 can be lubricated. Cooling and lubrication can be performed efficiently.

  The present invention is not limited to the configuration of the above-described embodiment, and can be applied to a case where the piston 8 is formed of an iron-based metal or a two-cycle internal combustion engine.

  Moreover, the height of the convex part 34 can be freely set according to the magnitude | size and specification of a piston. Further, it is possible to provide a supply mechanism other than the oil jet.

It is a longitudinal cross-sectional view which shows the piston of the internal combustion engine concerning this invention. It is a front view of the piston of this embodiment. It is a right view of the piston of this embodiment. It is a left view of the piston of this embodiment. It is a bottom view of the piston of this embodiment. It is the sectional view on the AA line of FIG. A and B are explanatory views showing an injection direction of the oil jet of the present embodiment. It is the schematic of the internal combustion engine to which the piston of this embodiment is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 4 ... Crank chamber 8 ... Piston 12 ... Oil jet 20 ... Crown part 20a ... Upper surface 20c ... Back surface 21 ... 1st skirt part 22 ... 2nd skirt part 23/24 ... Apron part 25 ... Piston pin 26/27 ... Pin boss part 26a / 27a ... Pin hole 29 ... Oil ring groove 30/31 ... Communication hole (communication path)
32, 33 ... 1st, 2nd slit 34 ... Projection 35 ... 1st guide groove 36 ... 2nd guide groove 37 ... Overlay part

Claims (13)

Oil is provided to a piston of an internal combustion engine having an oil ring groove on the outer periphery of the crown portion, and a communication passage that communicates the inside of the crown portion and the oil ring groove on the thrust side and the anti-thrust side of the oil ring groove. An oil supply system for supplying,
An oil supply system comprising oil supply means for increasing or decreasing the oil supply amount on the thrust side and the anti-thrust side in accordance with the movement position of the piston during the cycle stroke of the internal combustion engine. The oil supply system according to claim 1,
A large amount of oil is supplied to the thrust side at the movement position of the piston at the top dead center side and the bottom dead center side, and at the intermediate movement position between the piston top dead center side and the bottom dead center side, a large amount of oil is supplied to the anti-thrust side. An oil supply system characterized by being configured to be supplied to An internal combustion engine piston comprising: an oil ring groove on an outer periphery of a crown portion; and a communication passage communicating the inner side of the crown portion and the oil ring groove on a thrust side and an anti-thrust side of the oil ring groove. ,
A piston for an internal combustion engine, wherein a convex portion for guiding and guiding oil to a thrust side and an anti-thrust side is provided on a back surface side of the crown portion in accordance with a moving position of the piston during a cycle stroke of the internal combustion engine. The piston of the internal combustion engine according to claim 3,
A large amount of oil flows to the thrust side at the top dead center side and bottom dead center side movement positions of the convex portion, and at the intermediate movement position between the piston top dead center side and bottom dead center side, the anti-thrust side A piston for an internal combustion engine, characterized in that it is arranged so as to flow in a large amount. The piston of the internal combustion engine according to claim 3 and 4,
A piston for an internal combustion engine, wherein the communication passages are provided at least one pair apart from each other in the circumferential direction of the piston. The piston of the internal combustion engine according to claim 5,
A piston for an internal combustion engine, wherein the pair of communication passages are provided in a circumferential range of the skirt portion on the thrust side and the anti-thrust side of the skirt portion of the piston. The piston of the internal combustion engine according to claim 6,
A piston for an internal combustion engine, wherein a slit is formed along each of the oil ring grooves between each of the pair of communication paths. An internal combustion engine piston comprising: an oil ring groove on an outer periphery of a crown portion; and a communication passage communicating the inner side of the crown portion and the oil ring groove on a thrust side and an anti-thrust side of the oil ring groove. ,
On the back side opposite to the top surface of the crown, a convex portion protruding in the crankshaft direction is formed,
The convex portion is formed at a position in the oil supply direction from the oil jet, and has a first guide surface inclined downward from the top toward the communication path, and a downward inclined shape from the top toward the center of the piston. And an oil supply direction from the oil jet is switched from one of the first guide surface or the second guide surface to the other according to the movement position of the piston. A piston for an internal combustion engine. In the piston of the internal combustion engine according to any one of claims 3 to 8,
A piston for an internal combustion engine, wherein the convex portion is formed in an arc shape along the circumferential direction of the piston on the back surface of the crown portion. In the piston of the internal combustion engine according to any one of claims 3 to 9,
A piston for an internal combustion engine, wherein the convex portion is formed in an arc shape in cross section. In the piston of the internal combustion engine according to any one of claims 3 to 10,
A piston for an internal combustion engine having a pair of pin bosses for supporting both ends of a piston pin, and a recess formed between the pin bosses on the back surface of the crown. The piston of the internal combustion engine according to claim 8,
The convex portion is a position where the extension line in the oil supply direction from the oil jet is directed to the first guide surface at the movement position of the piston at the top dead center side and the bottom dead center side, and A piston for an internal combustion engine, wherein an extension line in the oil supply direction is at a position directed toward a second guide surface at an intermediate movement position between the dead center side. The piston of the internal combustion engine according to claim 12,
The piston of an internal combustion engine, wherein the convex portion is provided on a thrust side.

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