JPH0749831B2 - Connection structure of piston and connecting rod - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for connecting a piston and a connecting rod in an internal combustion engine, and a structure for connecting the piston and the connecting rod which facilitates management of assembly dimensions.

[0002]

2. Description of the Related Art According to the connection structure of the piston and connecting rod of Japanese Patent Application No. 2-85663 filed by the present applicant, the swinging center of the connecting rod with respect to the piston is greater than that of the conventional connecting structure using piston pins. Is much closer to the crown surface of the piston, and if the crankshaft arm and the connecting rod are lengthened by that much, the displacement can be increased and the engine output can be increased without changing the dimensions of the cylinder.

As shown in FIG. 2, in the connection structure of the piston and the connecting rod described above, the presser foot 23 supported on the skirt portion 2a is used.
The spherical convex portion of the bowl-shaped receiving plate 16 at the tip portion of the connecting rod 21 is slidably supported in the spherical concave portion of the connecting rod 21, and the sliding body 9 having the spherical convex portion is sandwiched between the spherical concave portion of the receiving plate 16 and The piston crown portion 2a is supported so as to be slidable. The gap between the spherical concave portion of the presser foot 23 and the spherical convex portion of the receiving plate 16 and the gap between the spherical concave portion of the receiving plate 16 and the spherical convex portion of the sliding body 9 are defined by the skirt portion 2a of the holding cylinder 26 that supports the presser foot 23. It is adjusted according to the amount of screwing into the inner peripheral surface.

[0004]

Therefore, the assembly dimension h from the center 48 of the large end of the connecting rod 21 to the crown surface of the piston is determined from the center 48 of the large end of the connecting rod 21 to the spherical recess of the receiving plate 16. Differences occur in the compression ratio of the engine due to the machining error between the dimension c to the center, the thickness dimension d of the sliding body 9 and the thickness dimension e of the piston crown portion 2a and the clearance of the sliding contact portion. If it occurs and the assembly dimension is too long, the piston crown surface may collide with the intake / exhaust valve.

In view of the above problems, the object of the present invention is to easily control the machining dimensions and the assembly dimensions of the parts, and the assembly dimensions from the center of the large end of the connecting rod to the piston crown surface are always predetermined values. It is to provide a connecting structure of a piston and a connecting rod.

[0006]

In order to achieve the above object, the structure of the present invention comprises a spherical convex portion formed on the lower surface of the piston crown portion and a bowl-shaped receiving plate formed at the tip portion of the connecting rod. The spherical concave portion is slidably contacted, the spherical concave portion provided on the annular presser is slidably contacted with the lower surface of the receiving plate, and the stepped holding cylinder is screwed into the screw hole formed on the inner peripheral surface of the skirt portion to form the holding cylinder. The upper end surface of the holder is brought into contact with the inner end surface of the screw hole, and a shim is sandwiched between the holding surfaces of the holding cylinder to support the presser foot.

[0007]

In the present invention, the dimensions from the piston crown surface to the lower surface of the piston crown portion, the dimensions from the piston crown surface to the inner end surface of the screw hole of the skirt, and the upper end surface to the holding surface of the holding cylinder, which are easy to machine If the accuracy of each dimension up to is controlled, the holding cylinder that supports the presser can be tightened into the screw hole of the piston skirt until the upper end surface of the holding cylinder contacts the inner end surface of the screw hole. The dimension from the end center to the piston crown surface is assembled to a predetermined value. In this case, variations in assembly due to machining errors of the retainer, support plate, and sliding body that are sandwiched between the retaining surface of the retaining cylinder and the lower surface of the piston crown are due to the retaining surface of the retaining cylinder or the lower surface of the piston crown. If a shim that adjusts the gap is sandwiched, it is absorbed, and the assembly dimension from the center of the large end of the connecting rod to the piston crown surface can be accurately obtained.

It is also possible to preliminarily classify the slide body, the presser foot or the holding cylinder having different working errors, and select an appropriate one for assembly.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a piston 2 according to the present invention is provided with a combustion chamber 4 having an asymmetrical recess on the upper surface of a piston crown portion 2a, and a plurality of ring grooves 3 in the upper half of the outer peripheral surface. Is provided, and the inner peripheral surface of the skirt portion 2b has a screw hole 4
Processed to 7. The axial center of the piston crown 2a is the combustion chamber 4
Is protruded downward so as to surround the bottom of the protrusion, and the lower surface 7 of the protrusion is flat. An annular oil reservoir 5 is formed on the lower surface 7 of the piston crown portion 2a so as to surround the protruding portion. In order to reduce the weight and heat load of the piston crown 2a, the piston crown 2a
An empty portion 8 is provided on the lower surface 7 of the and is closed by a lid 8a.

To effectively cool the periphery of the combustion chamber 4 with oil, an annular partition plate 6 is fitted and supported in the oil sump 5. The partition plate 6 is provided with an inlet 6a formed by cutting out the outer peripheral edge portion of the partition plate 6 and an outlet 6b formed by a through hole, with the phases of 180 ° different. On the lower surface 7 of the piston crown portion 2a, the spherical convex portion 1
A sliding body 9 having 5 is superposed so as to be slidable.

A bowl-shaped receiving plate 16 is integrally formed at the tip of the connecting rod 21, and a spherical concave portion 17 of the receiving plate 16 is slidably engaged with a spherical convex portion 15 of the sliding body 9. In order to maintain the engagement between the spherical concave portion 17 of the receiving plate 16 and the spherical convex portion 15 of the sliding body 9, the spherical convex portion 18 on the lower surface of the receiving plate 16 has an annular pressing member 2.
It is slidably supported in the spherical concave portion 24 of No. 3. The receiving plate 16 is provided with an axial passage 19 substantially in the axial center of the spherical recess 17, and an outlet passage 20 penetrating the connecting rod 21 in the front-back direction.
Is communicated with.

An axial passage 13 for lubrication and an annular groove 12 are formed on the flat upper surface of the sliding body 9. A plurality of groove passages 34 connecting the groove 12 and the passage 13 on the upper surface of the slide body 9.
Is provided. Inside the slide body 9, a plurality of passages 10 extending from the outer peripheral surface to the groove 12 and a plurality of passages 14 extending from the groove 12 to the spherical convex portion 15 are provided. The lower half of the passage 13 has a large diameter in order to reduce the weight of the sliding body 9.

For convenience of assembling the presser foot 23 to the lower side of the receiving plate 16, the presser foot 23 is formed by combining two divided bodies in an annular shape, and the sleeve 22 is fitted on the presser foot 23. The presser foot 23 is fitted in the holding cylinder 26, and the lower end surface of the presser foot 23 is supported by the step portion, that is, the holding surface 25 of the stepped holding cylinder 26 screwed into the screw hole of the skirt portion 2b.

In order to prevent the holding cylinder 26 from loosening, an annular groove 28 is provided on the inner peripheral surface of the skirt portion 2b.
A retaining ring 27 is engaged between the conical surface 28 a of No. 8 and the lower end surface of the holding cylinder 26. The retaining ring 27 is elastically expanded and deformed so that the lower conical surface engages with the conical surface 28a of the annular groove 28.
The holding cylinder 26 is prevented from being loosened regardless of how much the holding cylinder 26 is screwed.

In order to suppress the rotation of the piston 2 around the axis with respect to the connecting rod 21 and to allow the connecting rod 21 to swing left and right with respect to the piston 2, a pair of left and right in the meridian direction are formed in the spherical recess 24 of the presser 23. The groove 24a is formed and the receiving plate 16 is formed.
The sphere 29 coupled to the spherical convex portion 18 is engaged with the groove 24a. A ball 30 coupled to the inner surface of the upper wall of the sleeve 22 having an inverted L-shaped cross section that is externally fitted to the presser 23 is engaged with a hole in the upper end surface of the presser 23. Sphere 31 coupled to the outer peripheral surface of the sleeve 22
Is engaged with an axial groove 32 provided on the inner peripheral surface of the skirt portion 2b.

The presser foot 23 is provided with an inlet passage 33 extending toward the inlet 6a of the partition plate 6, and oil is jetted toward the inlet passage 33 from an oil jet provided at the lower end of a cylinder (not shown). It The oil injected from the oil jet flows into the oil reservoir 5 through the inlet passage 33 and the inlet 6a of the partition plate 6, where it is divided into two parts and circulates the oil reservoir 5 in the opposite direction to cool the piston crown portion 2a. Then, it flows out from the outlet 6b on the opposite side to the space below the partition plate 6.

The oil in the lower space of the partition plate 6 flows into the groove 12 through the passage 10, and the oil in the groove 12 flows in the groove passage 34 in the sliding member 9.
Lubricates the sliding contact portion between the piston and the crown portion 2a of the passage 13, 1
9 and also lubricates the sliding contact portion between the spherical concave portion 17 and the spherical convex portion 15 through the passage 14 to flow into the passage 19. The oil in the passage 19 flows out of the connecting rod 21 through the outlet passage 20 and returns to the crank chamber (not shown). Further, the oil in the empty space below the partition plate 6 lubricates the sliding contact portion between the spherical concave portion 24 of the retainer 23 and the spherical convex portion 18 of the receiving plate 16.

As shown in FIG. 2, according to the present invention, in order to obtain a predetermined assembly size (the length from the center 48 of the large end of the connecting rod 21 to the crown surface of the piston), the piston 2 is
The dimension e from the piston crown surface to the lower surface 7 of the piston crown portion 2a and the dimension b from the piston crown surface to the inner end surface 46 of the screw hole 47 are finished to predetermined dimensions. This processing is easy because it is based on the piston crown surface. Further, regarding the holding cylinder 26, the dimension a from the upper end surface to the holding surface 25
To the specified dimensions. With this processing, if the holding cylinder 26 is screwed into the screw hole 47 of the piston 2 until the upper end surface of the holding cylinder 26 contacts the inner end surface 46 of the screw hole 47, the holding cylinder 26 and the lower surface 7 of the piston crown portion 2a are held. Between the surface 25,
The sliding body 9, the receiving plate 16, and the presser foot 23 are sandwiched,
The error in the axial position of the receiving plate 16 with respect to the piston 2 is absorbed by inserting the shim 7a between the piston crown portion 2a and the sliding body 9 or by inserting the shim 25a between the holding surface 25 and the presser 23. A predetermined assembly dimension h is obtained.

Instead of using shims, the dimension d of the sliding body 9
The dimension k of the presser foot 23 and the dimension a of the holding cylinder 26 may be selected and combined from those previously classified according to the degree of processing error.

In each of the above-described embodiments, the sliding body 9 having the spherical convex portion 15 is slidably contacted with the lower surface 7 of the piston crown portion 2a, but they may be integrally formed.

[0021]

As described above, according to the present invention, the sliding member is brought into contact with the lower surface of the piston crown portion, and the spherical convex portion formed on the lower surface of the sliding member is provided with the bowl-shaped receiving plate formed at the tip portion of the connecting rod. Slide the spherical recessed part on the annular presser into the lower surface of the receiving plate, and screw the holding cylinder into the screw hole formed on the inner peripheral surface of the skirt part. Since the end surface is brought into contact with the inner end surface of the screw hole, the presser is supported on the holding surface of the holding cylinder, and the shim is sandwiched between the lower surface of the sliding body or the holding surface of the holding cylinder, the piston crown surface to the piston crown lower surface From the center of the large end of the connecting rod to the crown of the piston by simply controlling the dimensional accuracy of the connecting rod from the top surface of the holding cylinder to the holding surface. The assembly dimensions of can be obtained accurately, and the parts can be easily processed and assembled.

[Brief description of drawings]

FIG. 1 is a front sectional view showing a connecting structure of a piston and a connecting rod according to the present invention.

FIG. 2 is a front sectional view showing the structure in an exploded manner.

[Explanation of symbols]

 2: Piston 2a: Piston crown portion 2b: Skirt portion 7: Lower surface 7a: Shim 9: Sliding body 15: Spherical convex portion 15a: Groove 16: Receiving plate 17: Spherical concave portion 18: Spherical convex portion 21: Connecting rod 23: Presser foot 24: spherical concave portion 25: holding cylinder 25a: shim 26: holding cylinder 27: retaining ring 27a: conical surface 28: annular groove 28a: conical surface 46: inner end surface 47: screw hole

Claims (3)

[Claims] 1. A spherical convex portion formed on the lower surface of a piston crown portion is in sliding contact with a spherical concave portion of a bowl-shaped receiving plate formed at the tip of a connecting rod, and a spherical concave portion provided on an annular retainer is received. Slidably contact the lower surface of the skirt, and screw the stepped holding cylinder into the screw hole formed on the inner peripheral surface of the skirt to bring the upper end surface of the holding cylinder into contact with the inner end surface of the screw hole, and A connecting structure of a piston and a connecting rod, characterized in that a shim is sandwiched between holding surfaces to support a presser foot. 2. A spherical surface of a bowl-shaped receiving plate formed at the tip of the connecting rod by abutting a slide member having a flat upper surface and a spherical convex portion on the lower surface with a shim sandwiched between the flat lower surface of the piston crown portion. The spherical convex portion of the sliding body is slidably contacted with the concave portion, the spherical concave portion provided on the annular presser is slidably contacted with the lower surface of the receiving plate, and the stepped holding cylinder is provided in the screw hole formed on the inner peripheral surface of the skirt portion. A connecting structure of a piston and a connecting rod, characterized in that the upper end surface of the holding cylinder is screwed into contact with the inner end surface of the screw hole, and the presser is supported on the holding surface of the holding cylinder. 3. A piston and connecting rod connecting structure according to claim 1, wherein at least one of a holding cylinder, a sliding body and a presser having different dimensions is selected and assembled in place of the shim. Assembly method of connecting part of connecting rod.