JPH04109065A - Connecting structure between piston and connecting rod - Google Patents

Abstract

PURPOSE:To moderate the heat load of the piston peripheral wall so as to prevent the seizure of a piston ring by leading lubricating oil, jetted from an oil jet, into an annular space part from an inlet passage so as to cool the periphery of a combustion chamber while flowing through the annular space part, and returning this lubricating oil into a piston skirt part from an outlet passage. CONSTITUTION:A piston 2 for a diesel engine is provided with a recess 3 serving as a combustion chamber formed in a crown part 2a, and a protruding part 4 is further formed at the lower face center of the crown part 2a so as to partition an annular space part 6. The flat upper face 22 of a sliding body 21 is brought into slidable contact with the flat lower face 20 of the crown part 2a, and the spherical recessed face 12a of a supporting plate 12 formed at the tip part of a connecting rod 13 is slidably engaged with a spherical protruding face 5 formed at the lower face of the sliding body 21. A spherical protruding face 12b formed at the lower face of the supporting plate 12 is slidably supported on a spherical recessed face 8a formed at the upper end of a cylindrical keep member 8. In this case, the keep member 8 is provided with an inlet passage 43 and an outlet passage 44 spaced circumferentially in order to lead lubricating oil, force-fed to an oil jet 52, into the annular space part 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a piston-to-connecting rod connection structure in which the piston crown is effectively cooled by lubricating oil.

[Prior art w#] As shown in Figure 4.5, the present applicant previously filed patent application No. 2-8
According to No. 5663, a bowl-shaped receiving plate 12 formed at the tip of the continuous ring 13 is engaged with the convex surface 5 formed on the lower surface convex portion 4 of the piston crown 2a, and is engaged with the lower surface of the receiving plate 12. The patent application has been filed for a connection structure between a piston and a connecting rod, in which an annular presser member 8 is supported by a holding cylinder 9 screwed onto a skirt portion 7 of a piston 2.

According to the above-mentioned piston and connecting rod connection structure, the following effects can be obtained compared to the conventional connection structure using a piston pin. That is, if the swing center O of the connecting rod 13 is biased toward the top surface of the piston, and the arm length r of the crankshaft 16 and the length 1 of the connecting rod 13 are lengthened by the biased valve, the connecting rod 1
Piston 2 without increasing the maximum inclination angle (oscillation angle) of 3.
The stroke or displacement of the piston 2 is increased, the wasted volume at the top dead center of the piston 2 is reduced, and exhaust gas countermeasures can be easily taken. Even if the stroke of the piston 2 increases, the connecting rod 13
Since the maximum inclination angle of is not large, piston slap,
There are no associated problems such as friction loss, piston ring wear, or slap noise.

Since the surface pressure of the receiving plate 12 of the connecting rod 13 against the explosive load is low, this is advantageous for high engine turbocharging.

By the way, in the connection structure of the piston and connecting rod mentioned above,
Since the center of swing of the connecting rod is near the top of the piston, the overall length of the piston can be shortened, but if the piston crown is not cooled from the surrounding area, the sliding parts of the connecting rod and the piston crown, as well as the piston rings, will be damaged. There is a risk of getting stuck.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, an object of the present invention is to provide a piston and a connecting rod in which an annular cavity is formed between the combustion chamber of the piston crown and the peripheral wall of the piston, and the piston and the connecting rod are cooled by lubricating oil. The aim is to provide a connection structure for

[Means for Solving the Problem] In order to achieve the above object, the configuration of the present invention is such that a convex surface having an arcuate cross section formed on the convex portion at the center of the lower surface of the piston crown is replaced with a convex surface formed on the tip of the connecting rod. The concave surface of the plate has an arcuate cross section, and the convex surface of the lower surface of the receiving plate has an arcuate cross section. The convex surface of the lower surface of the receiving plate has an arcuate cross section. An inlet passage that forms an annular cavity closed by a presser member between them, supplies lubricating oil from an oil jet disposed at the lower end of the cylinder to the annular cavity, and an outlet that returns oil in the annular cavity to the skirt part. The passages are disposed in the holding member at intervals in the circumferential direction.

[Operation] The annular cavity between the convex portion of the piston crown that defines the combustion chamber and the peripheral wall of the piston is closed by a pressing member that supports the lower surface of the receiving plate of the connecting rod. The holding member is provided with an inlet passage and an outlet passage, and lubricating oil jetted from an oil jet disposed at the lower end of the cylinder is introduced from the inlet passage into the annular cavity,
It flows through the annular cavity to cool the surroundings of the combustion chamber and is returned to the piston skirt from the outlet passage. Therefore, the piston circumference! The heat load on the piston ring is alleviated and seizure of the piston ring is prevented. Since the oil in the annular cavity also cools the sliding portion between the piston crown and the receiving plate of the connecting rod, seizure of the sliding portion is prevented.

[Embodiments of the Invention] FIG. 1 is a front sectional view of a piston and connecting rod connection structure according to the present invention. A piston 2 for a diesel engine has a well-known depression 3 as a combustion chamber formed in a crown 2a, and a plurality of annular grooves for mounting piston rings in a peripheral wall.
A cylindrical skirt portion 7 is formed in the lower half. Crown part 2a
A protrusion 4 is formed at the center of the lower surface of the holder, and an annular cavity 6 is defined between the protrusion 4 and the peripheral wall. A sliding body 21 made of a material with excellent wear resistance and thermal conductivity is provided on the flat lower surface 20 of the crown portion 2a.
The flat upper surface 22 of is slidably abutted.

A spherical convex surface 5 formed on the lower surface of the sliding body 21 and a spherical concave surface 12a of the receiving plate 12 formed on the tip of the connecting rod 13.
are slidably engaged.

A passage 24 is provided at the center of the sliding body 21, the upper end of the passage 24 communicates with the recess 23 of the upper surface 22, and the lower end of the passage 24 communicates with the recess 25 of the convex surface 5.

Lubricating oil is supplied from the internal passage 26 of the connecting rod 13 to the cavity between the recess 25 and the concave surface 12a. The lubricating oil lubricates the sliding parts between the upper surface 22 and the lower surface 20, and also lubricates the sliding parts between the concave surface 12a and the convex surface 5.
Lubricate the sliding parts.

A spherical convex surface 12b formed on the lower surface of the receiving plate 12 is slidably supported by a spherical concave surface 8a at the upper end of the cylindrical holding member 8. For convenience of assembly, the holding member 8 is formed by combining two parts, for example, and is slidably supported on the upper surface of the holding cylinder 9 with a slight bend. The holding tube 9 is screwed onto the skirt portion 7 and fastened with a lock nut 10 so as not to loosen.

The structure of the lower end of the connecting rod 13 is the same as that of the conventional one, but in the present invention, the lubricating oil supplied under pressure from the oil pump to one end of the crankshaft is connected to the crankshaft, crank arm,
The internal passages 26 of the connecting rod 13 are fed through the respective internal passages of the crank pins.

According to the present invention, the holding member 8 is provided with an inlet passage 43 in order to guide the lubricating oil supplied under pressure from the oil pump to the oil jet 52 disposed at the lower end of the cylinder into the annular cavity 6 of the piston crown 2a. Outlet passages 44 are arranged at intervals in the circumferential direction. In order to guide the oil to the upper space of the annular cavity 6 and to separate the oil in opposite directions and flow to the outlet hole 5o, a third
As shown in the figure, a branch with an inverted triangular cross section flows downward from the earthen wall of the annular cavity 6 in the part facing the inlet passage 43! ! 41 is highlighted. In order to effectively cool the upper space of the annular cavity 6, an annular partition plate 4 having an inverted U-shaped cross section is installed in the annular cavity 6.
2 is arranged, dividing the flow of the partition plate 42! ! A conical inlet hole 49 is provided in a portion opposite to 41 .

As shown in FIG. 1, the edge 42a of the partition plate 42 is curved downward to form the peripheral wall of the protrusion 4 of the piston crown 2a, that is, the inner periphery of the annular cavity 6. ! 6a. The edge 42b of the partition plate 42 is elastically engaged with the outer peripheral wall 6b of the annular cavity 6. An outlet hole 50 is provided at the outer edge of the partition plate 42 so as to face the outlet passage 44 .

According to the present invention, the oil jet 5 disposed at the lower end of the cylinder
The oil ejected from g! 4
1, and flows into the annular cavity 6 by dividing into left and right sides. The oil that has gone half way around the annular cavity 6 above the partition plate 42 cools the piston crown 2a, especially the peripheral wall of the recess 3 serving as a combustion chamber, and flows from the outlet hole 50 into the annular space between the partition plate 42 and the presser member 8. empty space 6
and further flows down to the crank chamber via the outlet passage 44 of the holding member 8.

On the earthen wall of the annular cavity 6 facing the entrance passage of the holding member 8,
Minute I of an inverted triangle! ! 41, the oil from the oil jet 52 is divided into three directions and flows evenly into the annular cavity 6, which also improves the cooling capacity.

If the partition plate 42 is sloped downward from the inlet hole 49 to the outlet hole 5o (the plate surface of the partition plate 42 is inclined with respect to the top surface of the piston), the oil flow will be improved and the cooling effect will be further improved. Ru.

Further, according to the present invention, in order to guide the oil scraped from the inner circumferential wall of the cylinder by the oil scraper ring on the lower side of the piston 2 to the inside of the skirt portion 7, the lower side of the oil scraper ring groove of the skirt portion 7 is provided. A small diameter portion 51 is formed. A large number of inclined passages 45 are provided in the skirt portion 7 at intervals in the circumferential direction. The inclined passage 45 communicates with an annular groove 46 formed in the inner circumferential wall of the skirt portion 7, and further communicates with a large number of passages 47 (see FIG. 2) provided in the holding cylinder 9. Therefore, the inner circumference of the cylinder is protected by the oil scraper ring! The oil scraped off flows down along the small diameter portion 51 and flows into the inclined passage 45, the annular groove 46,
It flows down through the passage 47 into the crank chamber.

In addition, in the above-mentioned embodiment, the convex surfaces 5, 12b and the concave surface 12a
, 8a are spherical, but they may also be protrusions or grooves with an arcuate cross section (having a --shaped cross section in the plane of the drawing). Moreover, the sliding body 21 may be formed integrally with the piston crown portion 2a without providing the sliding body 21.

[Effects of the Invention] As described above, the present invention relates the convex surface having an arcuate cross section formed on the convex portion at the center of the lower surface of the piston crown to the concave surface having an arcuate cross section of the receiving plate formed at the tip of the connecting rod. A convex surface having an arcuate cross section on the lower surface of the receiving plate is supported by a concave surface having an arcuate cross section of a presser member supported on the skirt portion, and a space between the periphery of the convex portion and the peripheral wall of the piston is closed by the presser member. An annular cavity is formed, and an inlet passage that supplies lubricating oil from an oil jet disposed at the lower end of the cylinder to the annular cavity, and an outlet passage that returns oil from the annular cavity to the skirt part are connected in the circumferential direction to the holding member. Unlike conventional pistons, there is no boss part that supports the piston pin, so one or more inlet passages that lead oil from the oil jet to the annular cavity can be arbitrarily provided. The cooling capacity can be improved.

Unlike conventional pistons, there is no boss part that supports the piston pin, so a large-capacity annular space can be formed between the convex part that projects downward from the piston crown and the piston peripheral wall, and the combustion chamber peripheral wall and piston Zhou! (Ringland) can be effectively cooled.

[Brief explanation of drawings]

Fig. 1 is a front sectional view showing the connection structure between a piston and a connecting rod according to the present invention, Fig. 2 is a bottom view of the same, Fig. 3 is a side sectional view of the vicinity of the inlet hole of the annular cavity, and Fig. 4 is the main body. FIG. 5 is a front sectional view showing a connection structure between a piston and a connecting rod to which the invention is applied, and FIG. 5 is a side sectional view thereof. 2: Piston 2a: Crown 5: Convex surface 6: Annular cavity
7: Skirt portion 8: Pressing member 8a: Concave surface 12: Receiving plate 12a: Concave surface 12b: Convex surface 13: Connecting rod 43:
Inlet passage 44: Outlet passage 52: Oil jet patent applicant Isuzu Motors Co., Ltd.

Claims (1)

[Claims] The convex surface with an arcuate cross section formed on the convex part at the center of the lower surface of the piston crown is engaged with the concave surface with an arcuate cross section of the strike plate formed at the tip of the connecting rod, and the convex surface with an arcuate cross section on the lower surface of the strike plate. is supported on a concave surface having an arcuate cross section of a presser member supported on the skirt portion, and an annular cavity closed by the presser member is formed between the periphery of the convex portion and the peripheral wall of the piston, and is disposed at the lower end of the cylinder. An inlet passage that supplies lubricating oil from the oil jet to the annular cavity, and an outlet passage that returns the oil in the annular cavity to the skirt part.
A connecting structure for a piston and a connecting rod, characterized in that the retaining member is arranged at intervals in the circumferential direction.