JPH0324860Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a piston for an internal combustion engine, and particularly to a piston used in an internal combustion engine equipped with an oil injection type piston cooling device.

[Prior Art] As the output of internal combustion engines increases, the top wall of the piston, which is located inside the cylinder bore and forms part of the wall of the combustion chamber, is exposed to a severe thermal load and requires forced cooling. ing.

As a piston cooling device that forcibly cools the top wall of the piston, engine lubricating oil is injected from the inner space of the piston body having a cup-like structure toward the top wall of the piston, and the engine lubricating oil cools the piston. An oil injection piston cooling device that cools the top wall has already been proposed, and in order to more effectively cool the piston top wall with such an oil injection piston cooling device, a In order to temporarily catch the injected lubricating oil and spray it again toward the top wall of the piston as the piston reciprocates,
It is known in Japanese Utility Model Publication No. 54-26424 and the earlier Utility Model Application No. 1983-1983 to install a shelf-shaped oil reservoir member forming an oil reservoir in the inner space of the piston body, facing the inner surface of the top wall of the piston. No. 185184 (Actual Publication No. 18518-
90055).

As described above, by inserting a shelf-shaped oil reservoir component into the inner space of the piston body and forming an oil reservoir facing the top wall of the piston body, the oil injection device can direct the oil to the top wall of the piston body. The lubricating oil sprayed toward the inner surface of the top wall is received by the oil reservoir after once cooling the top wall, and when the piston reaches its top dead center again, the inertial force acting on the oil The lubricating oil is again sprayed onto the inner surface of the piston top wall, and by spraying the lubricating oil again or spraying it again, better cooling of the piston top wall can be achieved.

In this case, as new lubricating oil is sequentially supplied from the oil injection device toward the space between the top wall of the piston body and the shelf-shaped oil reservoir component, some of the oil is removed from this space. However, when this overflowing oil flows down along the inner circumferential wall of the inner space of the piston body, especially along the part located exactly in the middle between the pair of bosses, the piston top wall It is located at the farthest distance from the pair of bosses and is least susceptible to the effect of heat being dissipated from the boss through the connecting rod, achieving the favorable effect of better cooling the portion that is easily overheated. . Therefore, when attaching the shelf-shaped oil sump component forming the oil sump to face the inner surface of the top wall portion of the piston body, it is necessary to attach the oil sump component and one of the inner peripheral walls of the inner space of the piston body. By providing an appropriately sized gap between the intermediate portions of the boss portions to allow oil to overflow from the oil reservoir, one particularly favorable effect regarding piston cooling can be obtained.

In one embodiment of the piston disclosed in the above-mentioned Japanese Utility Model Publication No. 54-26424, the shelf-shaped oil reservoir component is located only at the top of the piston body at its center. It is held between the central part of the wall part and the end of the connecting rod facing it, and is held between a pair of boss parts on the inner circumferential wall of the top wall part of the piston body. A gap suitable for obtaining the above effect is left between the intermediate portion and the shelf-shaped oil reservoir component facing it.

[Problem to be solved by the invention] However, as in the above-mentioned embodiment of the above-mentioned Utility Model Publication, the shelf-shaped oil reservoir constituent member has only a central portion facing the central portion of the top wall of the piston body. In a structure in which the piston is sandwiched between the top wall of the piston body and the connecting rod, a relative displacement occurs between the top wall of the piston body and the connecting rod as the piston reciprocates. Therefore, it is considered difficult to stably hold the shelf-shaped oil reservoir component at a predetermined mounting position.

Further, in the above-mentioned Utility Model Application No. 57-185184, both ends of the shelf plate portion of the oil reservoir component are located midway between a pair of boss portions on the inner circumferential wall of the inner space of the piston body. The piston pin is in contact with the piston pin, thereby preventing rotation of the pair of leg parts around the attachment part to the piston pin, so that no gap is left in this part. There is.

In the present invention, a shelf-shaped oil reservoir member is inserted into the inner space of the cup-shaped piston body and forms an oil reservoir facing the inner surface of the top wall of the piston body.
For internal combustion engines having a structure in which the internal peripheral wall of the inner space of the piston body is stably mounted in a spaced apart state so as to provide a gap between the pair of boss parts and the intermediate part between the two boss parts. Our goal is to provide pistons.

[Means for Solving the Problems] According to the present invention, the problem is solved by the present invention, which includes a top wall portion, a peripheral wall portion, and a pair of boss portions that protrude inwardly facing each other, and a piston pin hole is formed in the boss portions. A piston body having an open space, a shelf plate portion inserted into the inner space of the piston body and forming an oil reservoir recess facing the inner surface of the top wall portion, and a shelf plate portion bent from both side edges of the shelf plate portion. an oil reservoir forming member having a pair of leg portions, the boss portion having a cylindrical engagement portion having an elliptical outer peripheral surface, and the leg portion having the cylindrical engagement portion; An elliptical engagement hole is provided that fits exactly into the piston, and when the engagement hole in the leg portion of the oil reservoir component engages with the cylindrical engagement portion, the piston This is achieved by a piston for an internal combustion engine, characterized in that the piston is mounted to the main body so as not to move in any direction perpendicular to the central axis of the piston hole or in the direction of rotation around the central axis. Ru.

[Operation of the device] According to the structure of the present invention as described above, the oil reservoir component has a pair of bosses in which the oval engagement holes provided in the pair of leg portions form the piston pin holes in the piston body. Since the oil reservoir component is attached to the piston body while being engaged with the engaging part having an elliptical outer peripheral surface provided in the piston pin hole, the oil reservoir component can be moved in any direction perpendicular to the central axis of the piston pin hole. Also, it does not move relative to the piston body in the direction of rotation around the central axis, and therefore the shelf plate supported relative to the piston body by the pair of legs is held directly against the piston main body. Even if not, the end edge portion is held at an arbitrary predetermined position and spaced apart from the inner circumferential wall of the inner space of the piston body, and is located at an intermediate position between the pair of boss portions of the inner circumferential wall. The edge portions of the shelf board portions are maintained spaced apart from each other with an arbitrary designed gap.

Further, according to the configuration of the present invention, the oil reservoir component is attached with its pair of leg portions engaged with a pair of boss portions surrounding the piston pin hole, and the oil reservoir component is attached to the piston body with its pair of leg portions engaged with the pair of boss portions surrounding the piston pin hole. The oil sump component is completely installed within the piston body before the piston is connected to the connecting rod by the piston pin, and the piston pin is removed after assembly. Even when the piston is disassembled, the oil reservoir component remains assembled to the piston body.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 3 show one embodiment of a piston for an internal combustion engine according to the present invention. The piston for an internal combustion engine according to the present invention is composed of a piston body 1 and an oil reservoir component 10.

The piston body 1 is cast into a cup shape having a cylindrical peripheral wall part 2 and a top wall part 3 provided at one end of the peripheral wall part so as to close the one end. The inner surface 3a of the top wall portion 3 is recessed deeper from the periphery toward the center. A pair of boss portions 4 are formed on the inside of the peripheral wall portion 2 so as to bulge out toward the inner space of the piston body 1, facing each other. A piston pin hole 5 is provided along the line. A piston pin that connects the piston body 1 to a connecting rod (not shown) is inserted into the piston pin hole 5. Two piston ring grooves 6 are provided on the outer periphery of the top wall 3 and the peripheral wall 2.
and one oil ring groove 7 are provided.
The oil ring groove 7 communicates with the inner space of the piston body 1 via a slit hole 8.

Each boss portion 4 has an elliptical cylindrical engaging portion 9a having a smaller diameter than the outer periphery of the root portion on the outer periphery of the tip portion, and an annular end surface 9b located at the end portion of the cylindrical engaging portion on the root side. It has a stepped part 9.

As shown better in FIG.
2, and a pair of leg pieces 13 bent from both side edges of the shelf part 12 to one side, and the whole is press-formed from a metal plate having appropriate elasticity such as spring steel. It is made.

In the free state before attachment, the pair of leg pieces 13 are spread apart toward each other as shown in FIG. Oval cylindrical overhanging cylindrical portions 15 are provided which are formed by overhang press molding to protrude toward the other leg portion, that is, toward the inside.
An elliptical engagement hole 16 is formed by the overhanging cylindrical portion, and the engagement hole is adapted to be externally engaged with the cylindrical engagement portion 9a of the boss portion 4.

In the oil reservoir component 10, the shelf portion 12 is connected to the top wall portion 3.
By inserting the pair of leg parts 13 into the inner space of the piston body 1 in a state where they are elastically deformed in a direction toward each other so that the pair of leg parts 13 are opposed to each other and correspond to the boss part 4, It can be attached to the piston body 1 with one touch by spring action.

When the pair of leg portions 13 are inserted between the boss portions 4 and the engagement hole 16 is aligned with the cylindrical engagement portion 9a of the boss portion 4, the pair of leg portions 13 move away from each other due to their own spring force. The annular end surface 9 of the boss portion 4 is elastically deformed to the outer surface of the leg portion 13 around the engagement hole 16.
At the same time as being pressed against b, the cylindrical engaging portion 9 is pressed over the entire surface of the elliptical cylindrical inner circumferential surface of the overhanging cylindrical portion 15.
It is joined to the elliptical cylindrical outer peripheral surface of a. As a result, the engagement hole 16 circumscribes the cylindrical engagement portion 9a, and the oil reservoir component 10 is fixedly connected to the piston body 1 by its own spring action.

When the oil reservoir component 10 is fixed in the inner space of the piston body 1 as described above, the shelf plate portion 12 is a plane (horizontal plane) perpendicular to the axis of the piston body 1.
An oil sump depression 1 is provided near the top wall 3 extending along the
1 constitutes an oil reservoir, and a gap 17 is formed between the outer circumferential edge 12a and the inner circumferential surface portion 1a located midway between the pair of boss portions 4 of the inner circumferential surface of the piston body 1 facing the outer circumferential edge 12a. is formed.

Incidentally, as shown better in FIG. 3, a relatively large opening 18 is formed in one side of the oil reservoir component 10 in the vicinity of one end thereof between the piston body 1 and the piston body 1. It is used as an oil supply passage through which oil is injected by an oil injection nozzle (not shown).

Next, the behavior of the lubricating oil for cooling the piston in the piston configured as described above will be explained.
Lubricating oil for cooling the piston is supplied to the inner surface 3a of the piston body 1 through the opening 18 from an oil injection nozzle (not shown in the figure) fixedly disposed on the crank chamber side.
is sprayed towards. The lubricating oil injected from the nozzle is sprayed onto the inner surface 3a, and then falls onto the shelf plate portion 12 of the oil reservoir component 10, and forms the oil reservoir recess 11.
It accumulates in When the piston reaches the top dead center position, the lubricating oil accumulated in the oil sump depression 11 jumps up due to inertia and is sprayed onto the inner surface 3a of the piston body 1, causing the inner surface 3a to move from the side periphery to the center. Due to the concave shape, the water flows along the slope and cools the top wall portion 3 while concentrating in the center. During the downward movement of the piston, the relative speed of the lubricating oil from the nozzle to the inner surface 3a is high, so the lubricating oil injected from the nozzle violently collides with the inner surface 3a, cooling the inner surface and already adhering to the inner surface. The oil, which had been cooling the inner surface and whose temperature has risen somewhat due to heat reception, overflows to the outside of the space between the inner surface 3a and the shelf section 12.
A flow of lubricating oil through the outer space occurs. At this time, a part of this oil flows into the gap left between the wall portion 1a located at an intermediate position between the pair of boss portions 4 of the inner circumferential wall of the inner space of the piston body and the edge portion 12a of the shelf plate portion. 17, and further cools this part to a part of the top wall that is farthest from the boss 4 and is least susceptible to the cooling effect of the heat flow flowing from the boss 4 through the piston pin to the connecting rod. Provides additional cooling effect. When the piston reaches the bottom dead center position, the lubricating oil adhering to the inner surface 3a is separated from the inner surface 3a due to the action of inertia and falls onto the shelf plate portion 12 of the oil reservoir forming member 10. Shelf board part 12
has an oil reservoir recess 11 recessed on the side opposite to the inner surface 3a, so that the lubricating oil is absorbed into the oil reservoir recess 1.
The lubricating oil then jumps toward the inner surface 3a when the piston reaches the top dead center position, and cools the top wall 3 again.

[Effects of the invention] As described above, according to the invention, the shelf plate of the oil reservoir component is inserted into the inner space of the cup-shaped piston body and faces the inner surface of the top wall of the piston body to provide an oil reservoir. The leg portion of the piston pin hole may not move relative to the piston body from the hub portion of the piston body in any direction perpendicular to the central axis of the piston pin hole or in the direction of rotation around the central axis of the piston pin hole. Therefore, the shelf plate of the oil reservoir component is stably held by contact with the piston body even if it is not directly supported, and thereby the inner circumferential surface of the inner space of the piston body and the shelf plate are in contact with each other. Any desired gap can be provided between the inner circumferential surface of the piston body, and any preferable gap can also be provided between the portion of the inner circumferential surface of the piston body located at an intermediate position between the pair of hubs and the edge of the shelf plate portion facing thereto. Through this gap, the oil overflows from the limited space between the piston top wall and the shelf plate of the oil reservoir component, providing a favorable cooling effect to this part of the piston body. be able to.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of a piston for an internal combustion engine according to the present invention, FIG. 2 is a sectional view taken along the line - of FIG. 1, and FIG. 3 is a sectional view taken along the line - of FIG. 1.
FIG. 4 is a perspective view of an oil reservoir component incorporated in the piston for an internal combustion engine according to the present invention shown in FIGS. 1 to 3. 1... Piston body, 1a... Part of the inner peripheral surface,
2... Peripheral wall part, 3... Top wall part, 3a... Inner surface, 4
... Boss part, 5 ... Piston pin hole, 6 ... Piston ring groove, 7 ... Oil ring groove, 8 ... Slit hole, 9 ... Stepped part, 9a ... Cylindrical engagement part,
9b...Annular end surface, 10...Oil reservoir component, 1
1...Oil pool depression, 12...Shelf board section, 12a...
Outer periphery, 13... Leg piece part, 14... Leg piece part, 15
...Protruding cylindrical portion, 16...Engagement hole, 17...Gap, 18...Opening.

Claims (1)

[Scope of utility model registration request] A piston body having a top wall portion, a peripheral wall portion, and a pair of boss portions protruding inwardly facing each other, the boss portions having a piston pin hole, and a piston body inserted into the inner space of the piston body. an oil sump constituting member comprising a shelf plate section providing an oil sump recess facing the inner surface of the top wall section and a pair of leg pieces bent from both side edges of the shelf section; The boss portion has a cylindrical engagement portion having an elliptical outer circumferential surface, and the leg portion is provided with an elliptical engagement hole that exactly fits into the cylindrical engagement portion. When the engagement hole in the leg portion of the reservoir component engages with the cylindrical engagement portion, the reservoir component can also be applied to the piston body in any direction perpendicular to the central axis of the piston hole. A piston for an internal combustion engine, characterized in that it is mounted so as not to move in the direction of rotation around a central axis.