JPH0134685Y2 - - 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.

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.

Purpose of the Invention An object of the present invention is to provide a piston for an internal combustion engine that is configured to be more effectively cooled by lubricating oil than the previously proposed piston as described above.

Structure of the Device According to the present invention, the present invention has 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, and the oil reservoir component is provided in the inner space of the piston body. In a piston for an internal combustion engine in which lubricating oil is injected and supplied toward the back surface of the top wall, the oil sump component forms an oil sump recess on the side of the top wall, and the oil sump recess is drained. This is achieved by a piston for an internal combustion engine having a larger oil reservoir volume on the oil supply side than on the oil side.

Effects of the invention According to the above-described configuration, when the piston starts its downward movement from the top dead center position to the bottom dead center position, the lubricating oil that jumps up from the oil reservoir depression due to inertia adheres to the back surface of the top wall of the piston body. However, the amount of this adhesion is larger on the oil supply side than on the oil drain side due to the difference in oil reservoir volume in the oil reservoir depression, and as a result, the lubricating oil is directed from the oil supply side to the oil drain side on the back surface of the top wall. The lubricating oil for piston cooling is effectively exchanged, and the top wall of the piston in particular is effectively cooled. Also, when the piston moves upward from the bottom dead center position to the top dead center position, A large amount of new lubricating oil is received in the oil sump recess, and the piston is effectively cooled.

DESCRIPTION OF EMBODIMENTS The present invention will now be described in detail with reference to 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, is sloped upward from the side circumferential portion toward the center, and is formed in a substantially conical shape.
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 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 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 enters the inner space of the piston body 1 through a slit hole 8. It's communicating.

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 FIG. 4, the oil reservoir component 10 includes a substantially rectangular shelf section 12 having two oil reservoir recesses 11a and 11b, and one side from both side edges of the shelf section 12. It has a pair of leg pieces 13 which are bent to the same extent as shown in FIG. The entire structure is press-formed from a metal plate having appropriate elasticity, such as spring steel.

The oil sump recesses 11a and 11b are integrally formed with the shelf part 12 by drawing process, and the oil sump recesses 11
A is deeper than the oil reservoir depression 11b and has a larger oil reservoir volume than the oil reservoir depression 11b. In the free state before attachment, the pair of leg pieces 13 are spread apart toward each other as shown in FIG. An overhanging cylindrical portion 15 is formed by overhang press molding to protrude toward the other leg portion, that is, toward the inside, and an engaging hole 16 is formed by the overhanging cylindrical portion. The 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 plate portion 12 is located on the side closer to the piston body 1, a pair of leg portions 13 correspond to the boss portion 4, and another pair of leg portions 14 correspond to the guide groove 2a. A pair of leg pieces 13 in the direction posture
are inserted toward the inner space of the piston body 1 in a state where they are elastically deformed in a direction toward each other, and thereby are attached to the piston body 1 with a single touch by a spring action.

When the pair of leg portions 13 are inserted between the boss portions 4 and the hole 16 is aligned with the cylindrical engagement portion 9a of the boss portion 4, the pair of leg portions 13 are elastically moved away from each other by their own spring force. The outer surface of the leg portion 13 around the hole 16 is pressed against the annular end surface 9b of the boss portion 4, and at the same time the cylindrical engaging portion 9a is pressed on the inner circumferential surface of the overhanging cylindrical portion 15 over its entire surface. to be bonded to the outer peripheral surface of the As a result, the hole 16 is connected to the cylindrical engaging portion 9.
The oil reservoir constituting member 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.
1a and 11b constitute an oil reservoir.

As clearly shown in FIGS. 3 and 4, the shelf section 12 of the oil reservoir component 10 has wing sections 17a and 17b extending from the side edges near both ends thereof. has the function of catching oil, and is provided only on one side near one end, and only on the other side near the other end. As a result, as clearly shown in FIG. 3, the other side of the oil reservoir component 10 in the vicinity of the one end, that is, the side opposite to the wing portion 17a, is connected to the piston body 1. A relatively large opening 18 is formed therebetween, and a relatively large opening 19 is provided between the piston body 1 and the piston body 1 on one side near the other end, that is, on the side opposite to the wing portion 17b.
One of them, for example opening 18, is used as an oil supply channel, and the other, namely opening 19, is used as an oil drain channel.

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 from a nozzle 20 (see FIG. 2) fixedly disposed on the side of the crank chamber through the opening 18 toward the ceiling surface 3a of the piston body 1. When the piston is moving upward from the bottom dead center position to the top dead center position, the ceiling surface 3
The relative speed of the lubricating oil from the nozzle to a is small, and therefore the lubricating oil sprayed from the nozzle does not wet the entire ceiling surface 3a, but most of it falls onto the shelf board 12 of the oil reservoir component 10. The oil accumulates in the oil reservoir depressions 11a and 11b. The oil reservoir depression 11a is located near the oil supply side opening 18, and since the oil reservoir depression is larger than the oil reservoir depression 11b, it receives more new lubricating oil injected from the nozzle 20 than the oil reservoir depression 11b. store. When the piston starts to move downward from the top dead center position to the bottom dead center position, the oil sump depressions 11a and 1
The lubricating oil accumulated in the piston body 1b jumps up due to inertia and adheres to the ceiling surface 3a of the piston body 1, and the lubricating oil is deposited as the ceiling surface 3a slopes upward from the side periphery toward the center. As a result, the water flows along the slope and cools the top wall portion 3 while concentrating in the center. The lubricating oil that has jumped up from the oil pool depression 11a and the lubricant oil that has jumped up from the oil pool depression 11b collide with each other at the center of the ceiling surface 3a, and the lubricating oil that has jumped up from the oil pool depression 11a is higher than the lubricant oil that has jumped up from the oil pool depression 11a. The lubricating oil that has jumped up from the oil sump recess 11a because it is larger than the lubricating oil from the oil sump 11b flows from the oil supply side opening 18 side to the oil drain side opening 19 side while pushing back the lubricating oil that has jumped up from the oil sump recess 11b. flows towards During the downward movement of the piston, the relative velocity of the lubricating oil from the nozzle 20 with respect to the ceiling surface 3a is high, so that the lubricating oil injected from the nozzle 20 collides with the ceiling surface 3a and cools the ceiling surface. The lubricating oil adhering to the ceiling surface and flowing as described above is further pushed away toward the oil drain side opening 19 and flows. This allows efficient exchange of heat receiving oil 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 inertia and is separated by the ceiling surface 3a, forming an oil pool component. 10
It falls onto the shelf board section 12 of. The shelf board portion 12 has oil reservoir recesses 11a and 1 recessed on the side opposite to the ceiling surface 3a.
1b, the lubricating oil is accumulated in the oil reservoir recesses 11a and 11b, and the lubricating oil is then deposited on the ceiling surface 3a when the piston moves from the top dead center position to the bottom dead center position. The top wall portion 3 is cooled again.

Incidentally, as shown in FIG. 5, the oil sump depression 11 is not separated into the oil supply side and the oil supply side, and its depth becomes deeper as it goes from the oil drain side to the oil supply side. Also in this case, the same effects as in the above embodiment can be obtained.

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 drawings]

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.
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. FIG. 7 is a sectional view showing another embodiment. 1... Piston body, 2... Surrounding wall portion, 2a...
Guide groove, 3...Top wall portion, 3a...Ceiling surface, 4...
Boss part, 5... Piston pin hole, 6... Piston ring groove, 7... Oil ring groove, 8... Slit hole, 9... Stepped part, 9a... Cylindrical engaging part, 9
b...Annular end surface, 10...Oil reservoir constituent member, 1
1, 11a, 11b...Oil pool depression, 12...Shelf board part, 13...Leg piece part, 14...Leg piece part, 15...
...Protruding cylindrical portion, 16... Hole, 17a, 17b...
...wing part, 18, 19... opening, 20... nozzle.

Claims (1)

[Scope of utility model registration request] 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 lubricating oil is injected and supplied from a nozzle toward the back surface of the top wall. In the piston for an internal combustion engine, the oil reservoir forming member forms an oil reservoir recess on the side of the top wall portion, and the oil reservoir recess has a larger oil reservoir volume on the oil supply side than on the oil drain side. A piston for internal combustion engines characterized by: