JPH07113415A - Connecting structure of piston and connecting rod - Google Patents

Abstract

PURPOSE:To prevent a roller from rolling up from the arm of the small end part of a connecting rod when the connecting rod swings by holding the roller between guide plates in the case of a roller bearing, bending both end parts of one guide plate in the other guide plate direction, and bending both end parts of the other guide plate in one guide plate direction. CONSTITUTION:A retainer is eliminated in respective roller bearings 66, 76 in order to suppress rolling-up and rolling-down of the roller bearing 66 interposed between the upper surface of an arm formed in a half-cylindrical cross section and the bottom surface of a pillow and the roller bearing 76 interposed between the bottom surface of the arm and the half-cylindrical recessed part of a seat cylinder, and rollers 70, 80 are independently rolling-moved between two up and down thin guide plates 67, 68 and 77, 78 which are bent in a half- cylindrical shape. The both side rims 67b of the guide plate 67 is bent downward or in the guide plate 68 direction, and both end rims 68a of the guide plate 68 is bent upward or in the guide plate 67 direction. Both end rims 77a of the guide plate 77 is bent in the guide plate 78 direction, and one side rim 78a of the guide plate 78 is bent in a direction opposite to the guide plate 77, and the other end rim 78b is bent in the guide plate 77 direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting structure for a piston and a connecting rod in an internal combustion engine, and more particularly to a connecting structure for a piston and a connecting rod in which the smoothness and durability of the sliding portion at the small end of the connecting rod is improved. It is a thing.

[0002]

2. Description of the Related Art According to a connecting structure of a piston and a connecting rod disclosed in Japanese Patent Laid-Open No. 2-232934, the swing center of the connecting rod with respect to the piston is a piston crown surface as compared with a connecting structure using a conventional piston pin. If the arm of the crankshaft and the connecting rod are lengthened correspondingly, the displacement will be increased and the output of the engine can be increased without changing the dimensions of the cylinder block.

However, in the above connecting structure of the piston and the connecting rod, the small end portion of the connecting rod is sandwiched between the piston crown portion and the seat cylinder via the ball bearing, but the ball bearing has a spherical diameter. Even if the number of balls is reduced and the number of balls is increased, there is a problem that fretting occurs on the rolling surface of the connecting rod due to the contact surface pressure of the balls, and backlash is likely to occur in the rolling portion of the roller.

By inserting a roller bearing in place of the ball bearing into the sliding portion of the small end of the connecting rod, the contact surface pressure of the roller can be lowered to some extent, but the upper and lower surfaces of the small end of the connecting rod, that is, half of the connecting rod. Strict machining accuracy and durability are required not only for the cylindrical concave and convex surfaces, but also for the convex surface of the piston crown and the concave surface of the seat cylinder.

If a half roller bearing having a retainer is inserted into the sliding portion of the small end of the connecting rod, the following problems occur. The bearing load of the roller bearing is that the connecting rod swings from the neutral position (top dead center) to one side (forward) during the engine's explosion stroke.
When the connecting rod swings (moves forward) to the other side in the subsequent exhaust stroke, it decreases sharply. Therefore, in the explosion stroke of an engine in which the bearing load of the roller bearings is large, the cage for catching a large number of rollers is gradually raised to one side (the forward direction of the connecting rod) and cannot return. Finally, the retainer and a part of the roller come out of the arm at the small end of the connecting rod and hit the top wall of the inner sleeve.

When the connecting rod swings with the retainer and a part of the roller hitting the inner sleeve, the roller slides on the semi-cylindrical concave surface of the arm at the small end of the connecting rod without rolling. , The friction may increase, the rollers may wear, and the roller bearings may be damaged.

[0007]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is that, when the connecting rod swings, the rollers of the roller bearing roll between the upper and lower guide plates, and the arm at the small end of the connecting rod moves from the arm. It is to provide a connecting structure of a piston and a connecting rod which is prevented from rising.

[0008]

In order to achieve the above object, the structure of the present invention is such that a pair of arms having a semi-cylindrical cross section projecting to both sides are integrally formed at the small end of the connecting rod. A semi-cylindrical pillow is supported on the upper surface of the semi-cylindrical recess of the pair of arms via a roller bearing, and the lower surface of a pair of arms is supported on the semi-cylindrical recess on the upper end wall of the seat cylinder via a roller bearing. In addition, it is fitted inside the reverse cup-shaped inner sleeve, and the seat cylinder is fitted and fixed to the skirt of the piston. The roller bearing has a large number of upper and lower guide plates curved in a semi-cylindrical shape. By sandwiching the rollers, both end edges of one guide plate are bent toward the other guide plate, and both side edges of the other guide plate are bent toward the one guide plate.

[0009]

The roller bearing is formed by sandwiching a large number of rollers between two upper and lower guide plates which are curved in a semi-cylindrical shape and whose surface is hardened, and the rollers are not particularly restricted. For example, both edges of the lower guide plate are bent upward to prevent the rollers from rolling out in the circumferential direction. Both side edges of the upper guide plate are bent downward to prevent the rollers from coming out in the axial direction.

The roller bearing is mounted on the sliding portion between the piston and the small end of the connecting rod, and oil is supplied from the internal oil passage of the connecting rod between the rollers to lubricate the rolling portion of the roller.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a front sectional view showing a connecting structure of a piston and a connecting rod according to the present invention, in which hatching of a crown portion and a skirt portion of the piston is omitted. Piston 2 is crown 2a
A combustion chamber 4 consisting of an asymmetrical depression is provided on the upper surface of
A plurality of ring grooves 3 are provided in the upper half of the outer peripheral wall. The central portion of the crown 2a is projected downward so as to surround the bottom of the combustion chamber 4, and the lower surface 2b of the crown 2a is flattened. An annular cooling oil chamber 5 that surrounds the combustion chamber 4 is formed on the lower surface 2b of the crown portion 2a.

The connecting rod 21 has a pair of arms 16 having a semi-cylindrical or gutter-shaped cross-section protruding laterally (in the crankshaft direction) at its small end.
Are integrally formed. The upper surfaces 16a of the pair of arms 16 form a continuous semi-cylindrical recess. The pair of arms 16 are swingably held by the semi-cylindrical or semi-cylindrical pillow 9 and the seat tube 23 inside the inverted cup-shaped inner sleeve 61. The upper surface 9a of the pillow 9 is engaged with the shallow groove 30 provided in the top wall 61a of the inner sleeve 61. The pillow 9 has a lower surface 9b supported by a roller bearing 66 so as to be relatively swingable on an upper surface 16a forming a semi-cylindrical recess of the pair of arms 16.

The seat cylinder 23 fitted into the inner sleeve 61 is abutted against the intermediate step portion 61c of the inner sleeve 61, and is a portion of the annular groove 23b provided on the outer peripheral wall, and cannot be removed from the inner sleeve 61 by the retaining ring 65. Is held down. The retaining ring 65 is locked in an annular groove formed in the peripheral wall 61b of the inner sleeve 61. The seat tube 23 is provided with an elongated opening 40 in the front-rear direction (the left-right direction in FIG. 1) for penetrating the connecting rod 21, and the upper end wall of the seat tube 23 is provided with a pair of semi-openings on both side wall portions of the opening 40. A cylindrical recess 23a is formed. The lower surface 16 b forming the semi-cylindrical convex portion of the arm 16 is fixed by the roller bearing 76 to the seat tube 23.
It is swingably supported in the semi-cylindrical recess 23a.

As shown in FIG. 3, the seat cylinder 23 is provided with an opening 40 whose horizontal cross section is an elongated rectangle in the front-back direction (direction perpendicular to the crankshaft), and the opening 40 of the opening 40 is attached to the upper end wall of the seat cylinder 23. Semi-cylindrical recesses 23a are formed on both sidewalls in a direction crossing the opening 40. The dimension a of the opening 40 in the front-rear direction is longer than the entire length of the arm 16, and the dimension b of the opening 40 in the lateral direction (crank axis direction) is wider than the width of the arm 16. Figure 3
As shown by the phantom line, if the pair of arms 16 are directed in the front-back direction of the opening 40, the small end of the connecting rod 21 can penetrate the opening 40, and if the connecting rod 21 is rotated by 90 °, the pair of arms 16 is rotated. The arm 16 can be supported in the semi-cylindrical recess 23a.

As shown in FIG. 1, the seat cylinder 23 is supported on a plurality of projecting pieces 27 formed on the inner peripheral wall of the lower end of the skirt portion 2c. The projecting pieces 27 are arranged on the lower end inner peripheral wall of the skirt portion 2c at equal intervals in the circumferential direction, and project radially inward from the lower end inner peripheral wall. The seat tube 23 has an axial groove 23d and a ridge 23c which are wider than the projecting piece 27 in the lower half portion of the outer peripheral wall (dimensions in the circumferential direction).
Is provided. In order to fit the seat cylinder 23 into the skirt portion 2c, the groove 23d is engaged with the protrusion 27 and the seat cylinder 23 is pushed into the skirt portion 2c. Next, when the seat tube 23 is rotated by a predetermined amount, the protrusion 23c of the seat tube 23 overlaps the projecting piece 27.

As shown in FIG. 1, the crown portion 2a of the piston 2 is shown.
The cooling oil chamber 5 that surrounds the
It is divided by. Oil injected from an oil jet (not shown) enters the annular cooling oil chamber 5 through the inlet oil passage 33 of the seat cylinder 23 and the oil passage (not shown) of the inner sleeve 61 to cool the crown portion 2a. While making a half turn, the oil passage 3 of the inner sleeve 61
4a (FIG. 2), returns to the crank chamber via the outlet oil passage 34 of the seat cylinder 23.

According to the present invention, the roller bearing 66 inserted between the upper surface of the arm 16 having a semi-cylindrical cross section and the lower surface of the pillow 9, and the lower surface of the arm 16 and the semi-cylindrical recess 23a of the seat tube 23 are provided. In order to prevent the roller bearings 76 inserted between them from rising or protruding, each roller bearing 66, 76 does not have a retainer, and two thin upper and lower guide plates 67, 68 and 77 curved in a semi-cylindrical shape. , 78 so that the rollers 70, 80 roll independently, and the guide plates 67, 68, 77, 78 are subjected to surface hardening treatment on their rolling surfaces. The roller bearing 66 may have the same length as the pillow 9, but it is preferable to dispose the roller bearing 66 divided in the longitudinal direction, for example, three roller bearings 66.

As shown in FIG. 4, the roller bearing 66 is constructed by sandwiching a large number of rollers 70 between a semi-cylindrically curved guide plate 67 and a guide plate 68, and the rollers 70 are not particularly restricted. Both side edges 67a of the guide plate 67 are located below or through the guide plate 68.
And both end edges 68a of the guide plate 68 are bent upward or toward the guide plate 67. The rollers 70 are restrained by the side edges 67a so as not to slip out in the axial direction. The rollers 70 are restrained by the both edges 68a so as not to roll out in the circumferential direction.

As shown in FIG. 5, the roller bearing 76 is also constructed by sandwiching a large number of rollers 80 between a semi-cylindrically curved guide plate 77 and a guide plate 78, and the roller 80 is not particularly restricted. Both end edges 77a of the guide plate 77 are bent toward the guide plate 78, and the rollers 80 are suppressed by the both end edges 77a from rolling in the circumferential direction. One side edge 78a of the guide plate 78
Is bent in the direction opposite to the guide plate 77, and is engaged with a groove 29 provided along the end wall 28 of the semi-cylindrical recess 23a of the seat tube 23 as shown in FIG. The other side edge 78 of the guide plate 78
b is bent toward the guide plate 77. The roller 80 is restrained by the end wall 28 and the side edge 78b so as not to slip out in the axial direction.

The roller bearings 66, 76 are two upper and lower semi-cylindrical guide plates 67, 68, 7 each having a thin surface hardening treatment.
Since it is sandwiched between 7 and 78 and attached to the sliding portion at the small end of the connecting rod 21, the lubricating oil flows from the internal oil passage 19 of the connecting rod 21 to the oil hole 64 (of the guide plate 68 of the roller bearing 66). 2) to flow between the rollers 70 to lubricate the peripheral surface of the rollers 70, and then through the gap between the both ends of the arm 16 and the end wall 28, the roller bearing 76.
It flows into between the rollers 80, lubricates the peripheral surface of the rollers 80, and returns to the crank chamber. Therefore, smooth rolling of the rollers 70, 80 can be obtained.

In the embodiment shown in FIG. 6, the roller bearing 66 has a guide plate 67 to prevent a large number of rollers 70 from being separated.
And a guide plate 68 are combined to form an assembly. That is, the guide plate 67 has the two side edges 67a whose thickness is thin,
A guide groove 69 is formed by bending the guide plate 68 toward the C-shape. The guide plate 68 is bent at both end edges 68a toward the guide plate 67, and further bent at both side edges of the end edge 68a so as to sandwich both end surfaces of the roller 70, and is engaged with the guide groove 69 of the guide plate 67. It Thus, the guide plate 68 is assembled to the guide plate 67, preferably the guide plate 68 on the arm 16.
The guide plate 67 is locked to the pillow 9 by an appropriate means. The guide plates 67 and 68 relatively move in the circumferential direction via the rollers 70, but the guide plates 68 can be lifted up from the arms 16 or the rollers 70 can be lifted up from the arms 16 as the connecting rod 21 swings. Nothing. The roller bearings 76 have substantially the same structure.

In the embodiment shown in FIG. 7, the guide plate 67 of the roller bearing 66 has a side edge 67b whose guide plate 68 is slightly thin.
It is curved in a C shape toward. On the other hand, the guide plate 68 has both edges 6
8a is bent toward the guide plate 67, and both side edges 6
8c is curved so as to sandwich both end surfaces of the roller 70, and is engaged with the inside of both side edges 67b of the guide plate 67. Roller bearing 76
Are configured in a similar manner.

[0023]

According to the structure of the present invention, when the connecting rod swings as described above, the upper and lower two guide plates of each roller bearing slide relative to each other, but the rollers always roll between the upper and lower guide plates. It moves and does not rise above the arm of the connecting rod.

By using the guide plate subjected to the surface hardening treatment as the rolling surface of the roller of the roller bearing, the semi-cylindrical surfaces of the pillow, the arm of the connecting rod and the seat cylinder are not damaged and the durability is improved. .

Since the guide plate subjected to the surface hardening treatment is used, it is not necessary to use an expensive material for the pillow and the holding cylinder, and the weight of the entire piston can be reduced by using a lightweight one.

Since the roller of the roller bearing rolls between the upper and lower guide plates, strict finishing accuracy is not required for each of the semi-cylindrical surfaces of the pillow, the holding cylinder, and the arm of the connecting rod, which helps to reduce the processing cost. .

Since the upper and lower guide plates of the roller bearing are combined, the rollers do not fall apart when the connecting rod is assembled and disassembled with respect to the piston, and the work is facilitated.

[Brief description of drawings]

FIG. 1 is a front sectional view showing a connecting structure of a piston and a connecting rod.

FIG. 2 is a side sectional view showing a connecting structure of the piston and the connecting rod.

FIG. 3 is a plan view of a seat cylinder in the connecting structure of the piston and the connecting rod.

FIG. 4 is a perspective view of a roller bearing in the connecting structure of the piston and the connecting rod.

FIG. 5 is a perspective view of a roller bearing in the connecting structure of the piston and the connecting rod.

FIG. 6 is a side view showing an end portion of a roller bearing according to a modified embodiment of the present invention.

FIG. 7 is a side view showing an end portion of a roller bearing according to another modified embodiment of the present invention.

[Explanation of symbols]

2: Piston 2c: Skirt 9: Pillow 16: Arm
16a: upper surface 16b: lower surface 21: connecting rod 23: seat cylinder 23a: semi-cylindrical recess 61: inner sleeve 66,7
6: Roller bearing 67, 68: Guide plate 67a: Side edge 6
8a: Edge 77, 78: Guide plate 77a: Edge 78
a, 78b: side edge

Claims (3)

[Claims] 1. A pair of arms having semi-cylindrical cross-sections projecting to both sides are integrally formed at a small end of a connecting rod, and a pair of arms are semi-cylindrically recessed on an upper surface thereof via roller bearings. It supports a cylindrical pillow, supports the lower surface of a pair of arms through a roller bearing in a semi-cylindrical recess provided on the upper end wall of the seat cylinder, and then fits it inside an inverted cup-shaped inner sleeve, The cylinder is fitted and fixed to the skirt of the piston, and the roller bearing sandwiches a large number of rollers between the upper and lower two guide plates that are curved in a semi-cylindrical shape. A connecting structure for a piston and a connecting rod, which is characterized in that one side of the other guide plate is bent toward one guide plate. 2. A guide groove is formed by bending both side edges of one guide plate into a C-shaped cross section, and both end edges of the other guide plate are bent toward one guide plate, and one guide plate is formed from both end edges. The connecting structure for connecting a piston and a connecting rod according to claim 1, further comprising a protrusion protruding into the guide groove. 3. A guide groove is formed by curving both side edges of one guide plate in a C-shaped cross section, and both end edges of the other guide plate are bent toward one guide plate, and both side edges are guided by one guide plate. The piston-connecting rod connection structure according to claim 1, wherein the piston-connecting rod is curved toward a plate and engaged with the guide groove.