JPH05321626A - Coupling structure between piston and connecting rod - Google Patents

Abstract

PURPOSE:To sufficiently cool the crown part of a piston and lubricate the slide part thereof with the use of a conventional pump by returning oil flowing out from a cooling sump in the crown part of the piston, into a crack chamber by way of the contact part having a coupling structure, so as to limit the volume of oil. CONSTITUTION:A convex spherical part 15 and an annular sump 5 surrounding the convex spherical part 15 are formed at the lower surface 7 of a crown part 2a of a piston, a concave spherical part 17 in a receiving plate 16 integrally incorporated with of the forward end part of a connecting rod 21 is slidably engaged therein with the convex spherical part 15 of the crown part 2a. An annular retainer 23 is supported to a skirt part 2b. A convex spherical part 18 at the lower surface of the receiving plate 16 is slidably supported in a spherical recess 24 in the retainer 23. Oil from an oil jet disposed in the lower part of a cylinder is led to the all sump 5 by way of an inlet passage 33 so as to cool the crown part 2a. Oil flowing out from the oil sump 5 is led to the slide contact parts of the convex spherical part 15 of the crown part 2a and the concave spherical part 17 of the receiving plate 16, and is then returned to a crank chamber by way of an outlet passage 21 formed in the connecting rod 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting structure of a piston and a connecting rod in an internal combustion engine, and more particularly to sending oil from an oil jet to an oil sump of the piston crown to cool the piston crown and sliding contact of the connecting structure. The present invention relates to a connecting structure of a piston and a connecting rod for lubricating a portion.

[0002]

2. Description of the Related Art According to the connecting structure of the piston and connecting rod of Japanese Patent Application No. 2-22698 filed by the present applicant, the swinging center of the connecting rod with respect to the piston is greater than that of the connecting structure using the conventional piston pin. Is much closer to the crown surface of the piston, and if the crankshaft arm and connecting rod are lengthened by that much, the displacement can be increased and the output of the engine can be increased without changing the dimensions of the cylinder.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above-described connecting structure of the piston and the connecting rod, the oil from the oil jet arranged at the lower end of the cylinder is supplied to the inlet side of the annular oil reservoir surrounding the combustion chamber of the piston crown. Then, the oil sump is divided into two parts on the opposite side in the circumferential direction to half-circulate, and after cooling the piston crown part, it is directly returned to the crank chamber from the outlet on the side opposite to the inlet.

However, in the above-mentioned structure, the amount of oil is larger than that of the conventional general internal combustion engine, and unless the capacity of the oil pump is increased, the oil pressure of the lubricating system is lowered, and the lubricating ability may be insufficient. is there.

In view of the above-mentioned problems, the object of the present invention is to use a conventional oil pump of a sufficient capacity by returning the oil, which has come out of the oil reservoir of the piston crown portion, to the crank chamber through the sliding contact portion of the connecting structure. It is an object of the present invention to provide a connecting structure of a piston and a connecting rod for obtaining cooling of a piston crown portion and lubrication of a sliding contact portion of the connecting structure.

[0006]

In order to achieve the above object, in the structure of the present invention, a spherical convex portion and an annular oil reservoir surrounding the spherical convex portion are formed on the lower surface of the piston crown portion, and the tip of the connecting rod is formed. The spherical recess of the receiving plate formed on the lower portion of the cylinder is slidably contacted with the spherical convex portion, and the annular presser having the spherical concave portion which is slidably contacted with the lower surface of the receiving plate is supported by the skirt portion, and the oil jet is provided at the lower end of the cylinder. An inlet passage that guides oil from the oil reservoir to the oil reservoir is provided in the retainer, and an outlet passage that guides the oil that flows out from the oil reservoir to the sliding contact portion between the spherical convex portion of the piston crown and the spherical concave portion of the receiving plate is connected to the connecting rod. It is provided.

[0007]

The oil from the oil jet arranged at the lower end of the cylinder flows into the oil reservoir through the inlet passage provided in the presser, from the inlet provided in the partition plate of the oil reservoir, and flows to the opposite sides in the circumferential direction. After cooling the crown, lubricate the sliding contact between the spherical projection of the piston crown and the spherical recess of the receiving plate of the connecting rod from the outlet on the side opposite the inlet of the partition plate, It is returned to the crank chamber from the outlet passage provided inside. Since the oil flow is throttled at the sliding contact portion, the decrease in hydraulic pressure and the amount of oil are suppressed, and sufficient cooling and lubrication can be achieved by the conventional oil pump having the capacity.

[0008]

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 crown portion 2a, and a plurality of ring grooves 3 on the upper half of the outer peripheral surface. The inner surface of the skirt portion 2b is formed into a screw hole. The axial center of the crown 2a is projected downward so as to surround the bottom of the combustion chamber 4, and the lower surface 7 of the projection is flat. An annular oil reservoir 5 is formed on the lower surface 7 of the crown portion 2a so as to surround the protruding portion. In order to reduce the weight and heat load of the crown portion 2a, an empty portion 8 is provided on the lower surface 7 of the crown portion 2a and is closed by a lid 8a.

In order 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. A sliding body 9 having a spherical convex portion 15 is superposed on the lower surface 7 of the crown portion 2a in a slidable manner.

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 of the receiving plate 16 is slidably supported on the spherical concave portion 24 of the annular presser 23. To be done. The receiving plate 16 is provided with an axial passage 19 approximately in the center of the spherical recess 17, and is communicated with an outlet passage 20 that penetrates the connecting rod 21 in the front-rear direction.

The lower end surface of the presser 23 is screwed into the screw hole of the skirt portion 2b, and the stepped portion of the stepped holding cylinder 26, that is, the holding surface 2 is held.
Held at 5. In order to prevent the holding cylinder 26 from loosening,
An annular groove 28 is provided on the inner surface of the skirt portion 2b, and a retaining ring 27 is engaged between the conical surface 28a of the annular groove 28 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, regardless of the amount of screwing of the retaining cylinder 26.
Prevent slack. The presser foot 23 is provided with an inlet passage 33 that extends toward the inlet 6a of the partition plate 6.
Oil is jetted toward an oil jet from an oil jet provided at the lower end of the cylinder (not shown).

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 fitted onto the presser foot 23 is engaged with a hole in the upper end surface of the presser foot 23. Sphere 31 coupled to the outer peripheral surface of the sleeve 22
Is engaged with an axial groove 32 provided on the inner surface of the skirt portion 2b. For the 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 onto the presser foot 23.

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 sliding 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.

Preferably, the sliding surface of each of the above-mentioned sliding contact portions is provided with a very shallow depression for retaining oil. The passage area of each passage is determined by the fluid resistance such that an oil amount suitable for the heat load of the piston is obtained.

The oil sprayed from the oil jet is held by the presser 23.
Of the oil reservoir 5 through the inlet 33a of the partition plate 6 and the inlet 6a of the partition plate 6.
Flowing in, where it splits into two parts and cools the crown portion 2a of the piston 2 while making a half turn around the oil sump 5 in the opposite direction, and the outlet 6 on the opposite side.
It flows out from b to the empty space below the partition plate 6. The oil in the empty space below the partition plate 6 flows into the groove 12 through the passage 10 and the groove 12
A part of the oil flows to the passage 19 through the groove passage 34 and the passage 13. At this time, the sliding contact portion between the upper surface of the sliding body 9 and the lower surface 7 of the crown portion 2a is lubricated. The remaining oil in the groove 12 passes through the passage 14 and lubricates the sliding contact portion between the spherical concave portion 17 and the spherical convex portion 15 to pass the passage 1.
Flow to 9. 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 presser 23 and the spherical convex portion 18 of the receiving plate 16 and returns to the crank chamber.

The oil flowing out from the oil reservoir 5 to the lower side of the partition plate 6 through the outlet 6b can be suppressed from flowing at each sliding contact portion, so that the amount of oil flowing through the oil reservoir 5 and each sliding contact portion can be suppressed. Therefore, the capacity of the oil pump for supplying oil to the oil jet is the same as that of the conventional general internal combustion engine and is sufficient.

In the above-described embodiment, the sliding body 9 having the spherical convex portion 15 is brought into sliding contact with the lower surface 7 of the crown portion 2a of the piston 2, but they may be integrally formed. In this case, the oil in the empty space below the partition plate 6 is guided to the sliding contact portion between the spherical concave portion 17 and the spherical convex portion 15 and returned to the crank chamber via the passage 19 and the outlet passage 20.

[0018]

As described above, the present invention forms a spherical convex portion and an annular oil reservoir surrounding the spherical convex portion on the lower surface of the piston crown portion,
The spherical concave portion of the receiving plate formed at the tip of the connecting rod is slidably contacted with the spherical convex portion, and the annular presser having the spherical concave portion slidably contacted with the lower surface of the receiving plate is supported by the skirt portion and is arranged at the lower end of the cylinder. An inlet passage that guides the oil from the installed oil jet to the oil reservoir is provided in the presser, and an outlet passage that guides the oil that flows out from the oil reservoir to the sliding contact portion between the spherical convex portion of the piston crown and the spherical concave portion of the receiving plate to the outside. Is provided on the connecting rod, and the oil that cools the piston crown lubricates the sliding contact portion of the connection structure and is returned to the crank chamber.
Since the amount of oil is throttled at the sliding contact portion, therefore, the capacity of the oil pump is sufficient as in the conventional case, and it is possible to avoid a decrease in oil pressure of oil sent to each lubricating system of the engine.

The work load of the connecting rod is reduced as compared with a lubricating structure in which oil is supplied from the lubrication portion of the crankshaft to the sliding contact portion between the receiving plate of the connecting rod and the sliding member via the internal passage of the connecting rod.

When the piston reciprocates, the oil flowing out from the outlet passage of the connecting rod sprinkles on the inner wall of the cylinder, which is also useful for lubricating the sliding contact portion between the cylinder and the piston.

[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 side sectional view of the same.

[Explanation of symbols]

 2: Piston 2a: Crown part 2b: Skirt part 5: Oil reservoir 15: Spherical convex part 16: Receiving plate 17: Spherical concave part 20: Exit passage 21: Connecting rod 23: Presser 24: Spherical concave part 25: Inlet passage

Claims (1)

[Claims] 1. A spherical convex portion and an annular oil reservoir surrounding the spherical convex portion are formed on the lower surface of the piston crown portion, and a spherical concave portion of a receiving plate formed at the tip of the connecting rod is slidably contacted with the spherical convex portion. An annular presser with a spherical recess that slidably contacts the bottom surface of the receiving plate is supported on the skirt, and an inlet passage for guiding the oil from the oil jet installed at the lower end of the cylinder to the oil sump is provided in the presser. A connecting structure for a piston and a connecting rod, characterized in that the connecting rod is provided with an outlet passage for guiding the oil flowing out to a sliding contact portion between a spherical convex portion of the piston crown portion and a spherical concave portion of the receiving plate.