JPH0535266B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a piston for an internal combustion engine, and more particularly to a piston used in an internal combustion engine equipped with an oil injection type piston cooling device.

BACKGROUND OF THE INVENTION In an internal combustion engine, overheating of engine parts must be absolutely avoided in order to maintain normal operation of the engine. The top wall of the piston, which is located in the cylinder bore and forms part of the wall of the combustion chamber, is exposed to relatively severe thermal conditions among other engine parts, and is subject to an increase in heat load as the engine output increases. As a result, forced cooling is becoming necessary.

As a type of piston cooling device that forcibly cools the top wall of the piston, engine lubricating oil is injected toward the top wall of the piston from the inner space side of the piston with a cup-shaped structure, and the piston is cooled by the engine lubricating oil. An oil injection type piston cooling device that cools the top wall portion is conventionally known. The piston has been improved so that the top wall can be effectively cooled by the oil injection type piston cooling device as described above. A piston equipped with a shelf-shaped oil reservoir member constituting an oil reservoir on the top wall side is disclosed in Utility Model Application No. 49-96796 (Utility Model Publication No. 54-26424).
Utility Application No. 55-42967 (Utility Application No. 156052)
-Already proposed in No. 188456.

Although pistons having oil reservoir components as described above achieve their intended purpose, they still have drawbacks regarding the manufacturability of the piston, the ease of assembling the oil reservoir component to the piston body, and the reliability of assembly. However, there is not enough information on these matters.

Purpose of the Invention The present invention facilitates the injection of oil toward the top wall of the piston by using a mounting structure that is easy to assemble and has excellent assembly reliability without requiring major changes to the piston body of general structure. At the same time, an oil receiving surface as large as possible is provided opposite the piston top wall to receive the oil once sprayed onto the piston top wall, and an appropriate amount of oil is removed from the space between the piston top wall and the oil receiving surface. It is an object of the present invention to provide a piston for an internal combustion engine in which an oil reservoir component is attached to a piston body, which can enhance the piston cooling effect for cooling the top wall of the piston by making it easy for oil to flow out.

Structure of the Invention According to the present invention, the above-mentioned object includes a cup-shaped piston body having a top wall portion at one end, and an oil reservoir component provided in the inner space of the piston body; The oil sump component is adjacent to an oil sump recess bordered by an edge in a substantially rectangular planar profile facing the top wall, and a pair of opposing corners along one diagonal of the rectangle. a shelf section having a pair of wing sections projecting laterally from the edge; and a pair of boss sections integrally connected to the shelf section and provided around the piston hole of the piston body. This is achieved by a piston for an internal combustion engine characterized by comprising a pair of leg portions that are engaged with each other and supported by the piston body.

Effects of the Invention As described above, in the piston for an internal combustion engine according to the present invention, the oil reservoir component can be attached to the piston body by effectively utilizing the boss portion around the piston pin hole that the piston body originally has. Therefore, the oil reservoir component can be reliably attached to the piston body with a simple structure without requiring any major changes to the piston body having a general structure.

In addition, the shelf portion protrudes laterally in proximity to an oil sump portion bordered by an edge of a substantially rectangular planar contour and a pair of corner portions facing each other along one diagonal of the rectangle. By having a structure having a pair of wing parts, the piston main body can be attached to the pair of leg parts by simply connecting the pair of leg parts integrally to both side edges of the edge of the rectangular planar contour. It is possible to provide a spring action that is convenient for attachment to the rectangular planar contour, and from the side of the pair of wing portions adjacent to a pair of corner portions facing each other along one diagonal of the rectangle from the edge of the rectangular planar contour. By projecting out, the oil receiving surface facing the piston top wall beyond the edge can be increased in this pair of wing parts, and the oil receiving surface facing the piston top wall can be increased along the other remaining diagonal line. At a pair of corners, a relatively large void can be obtained along the side edge of the edge, so one of these voids can be used to direct oil toward the top wall by oil injection. By using the supply passage as the oil inflow port and the other empty space as the oil outflow port from the space between the piston top wall and the shelf plate, the oil inflow port and the oil outflow port are separated by a large distance, and the oil inflow from the oil inflow port is made. The cooling effect of the oil for cooling the piston top wall can be maximized because the oil can be reliably moved to the oil outlet along a large circulation path while making sufficient contact with the piston top wall. I can do it.

DESCRIPTION OF EMBODIMENTS The invention will now be described in detail by way of embodiments 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 forming member 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 back surface 3a of the top wall portion 3, ie, the ceiling surface 3a of the inner space of the piston body 1, slopes upward from the side circumference toward the center. Note that the ceiling surface 3a may be formed into a substantially hemispherical shape. A pair of boss portions 4 are formed on the inside of the peripheral wall portion 2 to face each other and bulge toward the inner space of the piston body 1, and each of the pair of boss portions 4 is provided with a piston pin hole on the same axis. 5 is provided. A piston pin is inserted into the piston pin hole 5 to connect the piston body 1 to a connecting rod (not shown). Two piston ring grooves 6 and one oil ring groove 7 are provided on the outer periphery of the top wall 3 and the side peripheral wall 2, and the oil ring groove 7 passes through a slit hole 8 to the piston body 1.
It communicates with the inner space of.

Each of the boss parts 4 has a stepped part on the outer periphery of the tip part, which consists of a cylindrical engaging part 9a having a smaller diameter than the outer periphery of the root part, and an annular end surface 9b located at the end of the cylindrical engaging part on the root side. It has 9. On the inner circumferential surface of the piston body 1, the parts facing each other in the direction orthogonal to the axis of the piston pin hole 5, that is, the skirt parts, each have a relatively wide guide groove extending from the tip end thereof along the axis of the piston body 1. 2a is formed.

As clearly shown in FIGS. 4 and 5, the oil reservoir component 10 includes a substantially rectangular shelf section 12 having an oil reservoir recess 11, and one side from both side edges of the shelf section 12. A pair of leg pieces 1 formed by bending
3 and another pair of leg portions 14 bent toward one side from both end edges of the shelf portion 12, and the entire leg portion 14 is press-formed from a metal plate having appropriate elasticity such as spring steel. has been done. Each leg piece 13 is
A relatively small first piece 13a is bent along a first folding line A relative to the shelf board 12, and a leg is bent along a second folding line B relative to the first piece 13a. A relatively large second piece 1 forming the majority of the piece 13
3b, the distance La between the first folding lines A of the pair of leg portions 13 is equal to or slightly smaller than the distance Lb between the tip surfaces 4a of the pair of boss portions 4,
Distance Lc between the second folding lines B of the pair of leg pieces 13
is approximately equal to the distance Ld between the annular end surfaces 9b of the stepped portions 7 of the pair of boss portions 4, and the pair of leg portions 13 are in the free state before installation as shown in FIGS. 4 and 5. As shown in the figure, their legs are spread apart toward each other. Second piece 13b of leg piece 13
Each of the legs is provided with an overhanging cylindrical portion 15 formed to protrude toward the other leg portion, that is, inwardly, by bulging press molding from the second leg portion, and the overhanging cylindrical portion allows the engagement. A mating hole 16 is formed, and the mating hole 16 is formed in the cylindrical engaging portion 9a of the boss portion 4.
It is designed to be circumscribed and engaged with. second piece 1
The tip, ie, the lower end, of the boss 4 has a semicircular shape, and the outer diameter of the lower end is larger than the outer diameter of the tip of the boss 4.

The pair of leg pieces 14 are the guide grooves 2 of the piston body 1.
a, and in the free state before installation, as shown in FIG. 4, the distance Le between the tips is equal to the distance Lf between the bottoms of the pair of guide grooves 2a ( (see Figure 2).

As shown in FIG. 5, the oil reservoir component 10 has a shelf plate portion 12 located on the side closer to the piston body 1, a pair of leg portions 13 corresponding to the boss portion 4, and a pair of leg portions 13 corresponding to the boss portion 4. The piston body 1 is moved with the piece 14 in the direction corresponding to the guide groove 2a and with the pair of leg pieces 13 being elastically deformed in the direction toward each other as shown by the imaginary lines in FIG. By being inserted toward the inner space, it can be attached to the piston body 1 with a single touch by a spring action.

When the pair of leg portions 13 are elastically deformed in the direction toward each other as described above, the leg portions 13 are elastically bent along each of the first folding line A and the second folding line B. By doing so, a pair of leg pieces 1
3 is equal to or smaller than the distance Lb between the tip surfaces 4a of the boss portions 4, so that the pair of leg portions 13 can be inserted between the boss portions 4 without any force. When the oil reservoir component 10 is inserted into the inner space of the piston body 1 from the open end thereof, at the same time, the pair of leg portions 14 are elastically deformed and engage with the guide groove 2a to slide therein. As a result, the oil reservoir component 10 can be inserted into the piston 1 reliably and easily without wobbling as it is guided by the engagement between the pair of leg pieces 14 and the guide groove 2a. A pair of leg pieces 13 are inserted between the boss parts 4 and the holes 16
When the pair of leg pieces 13 are aligned with the cylindrical engaging part 9a of the boss part 4, the pair of leg pieces 13 are elastically deformed in the direction away from each other by their own spring force, and the outer surface of the second piece part 13b around the hole 16 is is pressed against the annular end surface 9b of the boss portion 4, and at the same time, the inner circumferential surface of the overhanging cylindrical portion 15 is joined to the outer circumferential surface of the cylindrical engaging portion 9a over its entire surface. Part 9
The oil reservoir forming member 10 is fixedly connected to the piston body 1 by its own spring action.

As can be seen from the above description, in the piston according to the present invention, the stepped portion is only provided on the outer periphery of the tip end of the boss portion, and the piston body can be attached to the oil reservoir component without making any major changes to the piston body for attaching the oil reservoir component. It will be appreciated that it can be easily and reliably attached to the piston body with one touch and without the need for special attachment parts or attachment tools.

The rotation around the piston pin hole 5 of the oil reservoir component 10 is prevented by the pair of leg portions 14 being pressed against the bottom of the groove 2a by their own spring force. Engagement part 9
This may be done by not forming the hole 16 and the hole 16 in a perfect circle.

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.
1 constitutes an oil reservoir.

As clearly shown in FIGS. 3 and 4, the shelf portion 12 of the oil reservoir component 10 has wing portions 17 extending from the side edges in the vicinity of both ends, and the wing portions drain the oil. It has a receiving function, and is provided only on one side near one end, and only on the other side near the other end.

As a result, as shown in Figure 3,
A relatively large opening 18 is formed between the piston body 1 and the piston body 1 on the other side near the one end of the oil reservoir component 10, and a relatively large opening 18 is formed on the other side near the other end. A relatively large opening 19 is provided between the piston body 1 and the piston body 1, one of which is used as an oil supply passage and the other as an oil discharge passage.

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 injected toward the ceiling surface 3a of the piston body 1 through the opening 18 from a nozzle (not shown) fixedly disposed on the side of the crank chamber. When the piston is moving upward from the bottom dead center position to the top dead center position, the relative speed of the lubricating oil from the nozzle to the ceiling surface 3a is small, and therefore the lubricating oil injected from the nozzle is moving upward from the ceiling surface 3a. Most of the oil falls onto the shelf board part 12 of the oil sump constituting member 10 and accumulates in the oil sump recess 11 without wetting the entire oil sump 3a. When the piston starts to move downward from the top dead center position toward the bottom dead center position, the lubricating oil accumulated in the oil sump recess 11 jumps up due to inertia as described above, and the piston body 1
Since the ceiling surface 3a is sloped upward from the side periphery toward the center, the lubricating oil flows along the slope and reaches the top wall 3.
While cooling, it gathers in the center (top). During the downward movement of the piston, the relative speed of the lubricating oil from the nozzle to the ceiling surface 3a is large, so that the lubricating oil injected from the nozzle reaches the ceiling surface 3a.
The lubricating oil that has already adhered to the ceiling surface is pushed away toward the opening 19 side while cooling the ceiling surface by colliding with the ceiling surface a. As a result, the heat-receiving oil is exchanged with new supplied oil. When the piston reaches the bottom dead center position and moves toward the top dead center position again, the lubricating oil adhering to the ceiling surface 3a is subjected to inertial action and peels off from the ceiling surface 3a, forming an oil reservoir component. 10 onto the shelf board section 12. The shelf board part 12 is on the ceiling surface 3a
By having the oil sump recess 11 recessed on the opposite side, the lubricating oil is accumulated in the oil sump recess 11, and the lubricating oil then moves from the top dead center position to the bottom dead center position. When moving, it jumps up toward the ceiling surface 3a and cools the top wall portion 3 again.

Most of the lubricating oil that is peeled off from the ceiling surface 3a due to inertia when the piston moves from the bottom dead center position to the top dead center position is caught by the shelf plate part 12, but some of the lubricant oil is caught by the boss part. The oil falls onto the upper surface 4b of 4, and flows downward from this, that is, into the oil pan. A part of this lubricating oil flows along the surface of the leg portion 13 and drips from the lower end of the leg portion 13 because the lower end edge thereof protrudes below the boss portion 4 . That is, the lower end of the leg portion 13 performs an oil draining action, thereby preventing the lubricating oil from adhering to the inner circumferential surface of the cylinder bore that receives the piston.

Incidentally, in order to obtain the above-mentioned oil draining effect more clearly, a protruding tongue piece 13c may be formed protrudingly from the lower end of the leg piece 13 as shown in FIG. 6, and as shown in FIG. As shown in FIG.
The lower end of the piston may be bent toward the center of the piston.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited to these, and it is understood that various embodiments can be made within the scope of the present invention. It will be clear to those skilled in the art.

[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.
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, and FIG. 5 is a cross-sectional view of the piston for an internal combustion engine according to the present invention. The exploded view, FIGS. 6 and 7 are cross-sectional views showing other embodiments of the piston for an internal combustion engine according to the present invention. 1... Piston body, 2... Surrounding wall portion, 2a...
Guide groove, 3...Top wall surface, 3a...Ceiling surface, 4...
Boss portion, 4a...Tip portion, 4b...Top surface portion, 5...
...Piston pin hole, 6...Piston ring groove, 7
...Oil ring groove, 8...Slit hole, 9...
Stepped portion, 9a...Cylindrical engagement portion, 9b...Annular end surface, 10...Oil pool forming member, 11...Oil pool depression, 12...Shelf plate portion, 13...Leg piece portion, 13a...
...First piece, 13b... Second piece, 13c...
...Protruding tongue piece, 14...Leg piece part, 15...Extruding cylindrical part, 16...Hole, 17...Wing part, 18, 19...
...opening.

Claims (1)

[Claims] 1. It has a cup-shaped piston body having a top wall at one end, and an oil reservoir component provided in the inner space of the piston body, and the oil reservoir component includes a main body facing the top wall. an oil sump recess bordered by an edge of a rectangular plane profile; and a pair of wing portions protruding laterally from the edge in proximity to a pair of opposing corners along one diagonal of the rectangle. and a pair of bosses that are integrally connected to the shelf board and are supported by the piston body by engaging with the outer peripheries of a pair of boss parts provided around the piston hole of the piston main body. A piston for an internal combustion engine, comprising a leg piece.