JPS633388Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a friction reduction device for a piston for an internal combustion engine.

During operation of an internal combustion engine, a piston reciprocates within a cylinder. Since there is a gap between the cylinder bore and the piston, the piston swings around the piston pin during reciprocating motion, and the piston skirt in the direction perpendicular to the axis of the piston pin moves into the cylinder bore. pressed against a surface. Therefore, pressure is generated between the piston and the cylinder bore surface. On the other hand, since the skirt portion of the piston is sliding in plane or line contact with the bore surface of the cylinder, frictional heat is generated between the piston and the bore surface of the cylinder. In this way, in order to reduce the frictional heat generated when the piston skirt comes into sliding contact with the cylinder bore surface, conventionally, rolling elements (rollers, balls, etc.) are provided on the piston skirt, and the skirt is brought into contact with the cylinder bore surface. There is one that is rolled into contact with the other. In conventional pistons, the rolling elements provided in the skirt portion come into contact with each other at the same location on the cylinder bore surface, so that only the bore surface of the cylinder that the rolling elements contact is partially worn out. When the local wear of the cylinder bore surface increases in this manner, the gap between the cylinder bore surface and the outer circumferential surface of the piston ring partially increases. Therefore, the function of the piston ring to seal combustion gas and the function of the oil ring to drain oil are significantly reduced.

In view of the above, the object of this invention is to provide a wear reduction device for a piston for an internal combustion engine that does not cause local wear to the cylinder bore surface.

Next, this invention will be explained based on embodiments shown in the drawings.

In FIGS. 1 and 2, inside a cylinder 1 of an internal combustion engine, there is a piston 2 that reciprocates within the cylinder 1. As shown in FIG. There is a gap C between the bore surface 1a of the cylinder 1 and the outer peripheral surface of the piston 2. Piston 2 has its piston head 2a
There are two ring grooves 3, 3 at the bottom, and an oil ring groove 4 is located below the lower ring groove 3. A piston ring 5 is fitted into each ring groove 3, and an oil ring 6 is fitted into each oil ring groove 4. The piston rings 5, 5 and the oil ring 6 are in sliding contact with the bore surface 1a of the cylinder 1. The piston 2 has a circumferential retaining groove 7 formed on the outer peripheral surface of the skirt portion 2b below the oil ring groove 4. A retaining groove 8 having the same shape as the retaining groove 7 is formed in the piston 2 adjacent to the lower end of the skirt portion 2b. A metal ball housing 9 fitted into the holding groove 7 has a ring shape, and an abutment 10 (see FIG. 3) is formed at one location. A ball 11 is attached to the outer periphery of the ball housing 9 so as to be rotatable at a predetermined pitch in the circumferential direction. The ball housing 9 is provided with oil holes 12 for supplying oil to each ball 11 from its inner circumferential side.

The two ball housings 9 are fitted into the holding grooves 7 and 8 of the piston 2 by widening the abutments 10, respectively. Each of the ball housings 9 fitted into the holding grooves 7 and 8 in this way has an outer diameter slightly larger than the inner diameter of the cylinder 1, similar to the piston ring 5, so that each ball 11 can be removed from the skirt portion 2b. The ball 11 is pressed against the cylinder bore surface 1a by protruding and maintaining an appropriate tension.

As described above, each ball 11 rotatably held by this ball housing 9 is pressed against the cylinder bore surface 1a, but each ball housing 9 itself is not fixed within the holding grooves 7 and 8. Therefore, when the piston 2 reciprocates within the cylinder 1, each ball 11 held in the ball housing 9 rolls against the cylinder bore surface 1a, and the ball housing 9 moves the piston 2 in each of the holding grooves 7 and 8. can freely move in the circumferential direction, and the contact position of the ball 11 held in the ball housing 9 with the cylinder bore surface 1a changes. For this reason, the cylinder bore surface 1
Only a specific part of a will wear out.

The piston 2 is provided with a suitable number of oil holes 7a and 8a, respectively, which communicate the inner peripheral surface of the piston 2 with the holding grooves 7 and 8. Therefore, oil scattered inside the piston 2 during reciprocating motion of the piston 2 enters the holding groove 7 through the oil hole 7a, and into the holding groove 8 through the oil hole 8a.
The oil in the holding grooves 7 and 8 passes through the oil hole 12 of each ball housing 9, and the oil in each ball housing 9 passes through the oil hole 12 of each ball housing 9.
to lubricate the ball 11. Therefore, each ball housing 9 in the holding grooves 7 and 8 and the ball 11 held in each ball housing 9
This prevents burn-in.

3 and 4 show another embodiment of the ball housing. A coil spring 13 is fitted onto the inner peripheral surface of this ball housing 9A. This coil spring 13 reinforces the tension of the ball housing 9A, and the ball 11 is attached to the cylinder bore surface 1a.
It acts to strengthen the pressing force. Furthermore, in FIG. 4, if there is a large gap between the upper surface of the ball housing 9A and the upper surface of the holding groove 8, a corrugated ring is installed in the gap in order to prevent the ball housing 9A from moving up and down within the holding groove 8. 14 is inserted. As shown in FIG. 5, the corrugated ring 14 has one abutment 14a.
4a is expanded and inserted into the holding groove 8.

FIG. 6 shows a roller housing 15 in which a roller 16 is rotatably attached in place of the ball 11 of the ball housing 9 in the first embodiment. Here, the roller 16 is drum-shaped, and the cylinder 1
It is designed to be able to roll against the bore surface 1a. The function of this roller housing 15 is the same as that of the ball housing 9 of the first embodiment.

FIG. 7 shows a third embodiment of the ball housing. This ball housing 17 differs from the ball housing 9 of the first embodiment in that an outer circumferential groove 18 is formed in its outer circumference. And this outer circumferential groove 18
A sub-ball housing 19 having one abutment (not shown) is fitted within the ball housing 17 with the abutment matching the abutment (not shown) of the ball housing 17. The sub-ball housing 19 is made of sheet metal, and the upper plate 19a, the rear plate 19b, and the lower plate 19c are each formed with curved surfaces at a predetermined pitch. Then, each plate 1 of the sub-ball housing 19
The ball 11 is rotatably supported by the curved surfaces 9a, 19b and 19c. The rear portions of the upper plate 19a and lower plate 19c of this sub-ball housing 19 are formed to push open the upper wall 17a and lower wall 17c of the ball housing 17, and the upper and lower walls 17a, 17c are used to hold the piston 2. It acts to press against the upper and lower surfaces of the groove 7 (or 8).

The sub-ball housing 19 of this embodiment holds the ball 11, and the ball housing 17 presses the ball 11 against the cylinder bore surface 1a. The ball housing 17 is connected to the retaining groove 7 of the piston 2.
(or 8), so piston 2
During operation, the ball housing 17 moves along the holding groove 7 (or 8). Therefore, the ball housing 1 having the sub-ball housing 19
7 has the same function as the ball housing 9 of the first embodiment. Note that 20 is an oil hole provided in the rear wall 17b of the ball housing 17, and 21 is an oil hole provided in the rear plate 19b of the sub-ball housing 19.

FIG. 8 shows another embodiment of a ball housing having a sub-ball housing. The ball housing 22 has ring-shaped holding plates 23 and 23 of the same shape facing each other upwardly and downwardly, each having one abutment (not shown), and is made of sheet metal on the inner periphery thereof and has one abutment (not shown). (not shown) is connected to the sub-ball housing 24. Here, the abutments between each holding plate 23 and the sub-ball housing 24 are aligned. Here, the upper and lower holding plates 23, 23 hold an appropriate number of balls 11 between them, similar to the ball housing 9 of the first embodiment. Further, the sub-ball housing 24 pushes both the holding plates 23, 23 apart in the circumferential direction by its spring force, and at the same time pushes the ball 11 against the cylinder bore surface 1a, it also pushes both the holding plates 23, 23 upward and downward. The holding plates 23 and 23 are spread out and pressed onto the upper and lower surfaces of the holding groove 7 (or 8) of the piston 2.

In the above embodiment, the skirt portion 2b of the piston 2 is provided with ball (or roller) housings at two locations, the upper and lower portions, but only the lower portion of the skirt portion 2b, that is, the retaining groove 8, is provided.
A ball (or roller) housing may be inserted into this holding groove 8.

As mentioned above, this idea consists of rotatably supporting a rolling member in an annular retaining groove provided in the circumferential direction on the outer periphery of the skirt portion of a piston for an internal combustion engine, and pressing the rolling member against the cylinder bore surface. By configuring the piston friction reducing device by fitting an annular housing having one abutment movable in the circumferential direction of the annular groove into the annular groove, the following effects can be obtained.

(1) The housing with the rolling member can move in the circumferential direction within the annular groove of the piston skirt, so when the piston is actuated, the rolling member that is pressed against the cylinder bore surface moves, so that the cylinder bore surface wear can be made uniform.

(2) Since the housing of the rolling member is annular and has one abutment, the housing itself can be given tension, so the rolling member can be brought into uniform contact with the cylinder bore surface.

[Brief explanation of the drawing]

The figures show an embodiment of this invention; Fig. 1 is a longitudinal sectional view of the piston in the cylinder, Fig. 2 is an enlarged view of the lower holding groove in Fig. 1, and Figs. 3 to 5 are a second embodiment. , FIG. 3 is a view corresponding to the - line cross section in FIG. 1, FIG. 4 is a view corresponding to FIG. 2, FIG. 5 is a perspective view of the corrugated ring in FIG. 4, and FIG. a partial sectional view of a housing with a roller as a moving member;
FIG. 7 is a sectional view of a ball housing having a sub-ball housing, and FIG. 8 is a sectional view of a ball housing having a sub-ball housing different from that in FIG. 1...Cylinder, 1a...Bore surface, 2...Piston, 2b...Skirt portion, 7, 8...Retaining groove,
9,9A...ball housing, 10...abutment,
11...Ball (rolling member), 15...Roller housing, 16...Roller (rolling member), 17...
... Ball housing, 18 ... Outer groove, 19 ...
Sub-ball housing, 22... Ball housing, 23... Holding plate, 24... Sub-ball housing.

Claims (1)

[Scope of utility model registration request] In the piston for an internal combustion engine, an appropriate number of rolling members capable of rolling on the bore surface are disposed in an annular retaining groove formed in the circumferential direction of the surface of the skirt portion that slides on the cylinder bore surface. An annular housing that rotatably supports the rolling member and presses the rolling member against the cylinder bore surface has an abutment and is movable in the circumferential direction of the annular groove. Features a friction reduction device.