JP2778228B2 - Connection structure of piston and connecting rod - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a connection structure between a piston and a connecting rod in which a piston crown is effectively cooled by lubricating oil.

[Prior Art] As shown in FIGS. 4 and 5, the present applicant has previously filed Japanese Patent Application No. 2-856.
No. 63 (Japanese Unexamined Patent Publication No. 3-288065), the upper surface of a bowl-shaped receiving plate 12 provided at the tip end of a connecting rod 13 is engaged with a convex surface 5 of a lower central portion 4 of a crown 2a of a piston 2. Then, a connecting structure of a piston and a connecting rod, in which an annular pressing member 8 engaged with the lower surface of the receiving plate 12 is supported on an upper end surface of a holding cylinder 9 screwed to the skirt portion 7, has been filed.

According to the connection structure between the piston and the connecting rod, the following effects can be obtained as compared with the conventional connection structure using a piston pin. That is, when the swing center O of the connecting rod 13 is biased toward the piston top surface and the arm length r of the crankshaft 16 and the length l of the connecting rod 13 are increased by the amount of the bias, the maximum inclination angle of the connecting rod 13 ( Without increasing the swing angle), the stroke of the piston 2, that is, the amount of exhaust, is increased, the dead volume at the top dead center of the piston 2 is reduced, and it becomes easier to take measures against exhaust gas. Even if the stroke of the piston 2 increases, the maximum inclination angle of the connecting rod 13 does not increase, so that there are no problems such as piston slap, friction loss associated therewith, wear of the piston ring, and slap noise. Since the surface pressure of the receiving plate 12 of the connecting rod 13 against the explosive load is low, it is advantageous for high supercharging of the engine.

By the way, in the connecting structure of the piston and the connecting rod described above, since the swing center of the connecting rod is near the piston top surface,
On the other hand, if the piston crown is not cooled from the surroundings, the sliding portion between the connecting rod and the piston crown or the piston ring may be seized.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, an object of the present invention is to form an annular space between a combustion chamber of a piston crown and a peripheral wall of a piston and cool the piston and a connecting rod by lubricating oil. To provide a connection structure.

Means for Solving the Problems In order to achieve the above object, according to the present invention, a flat upper surface of a sliding body is brought into contact with a flat surface formed at a lower central portion of a piston crown, and The convex surface of the circular cross section formed on the lower side is engaged with the concave surface of the circular cross section formed on the upper side of the receiving plate provided at the tip of the connecting rod, and the circular arc shape formed on the lower side of the receiving plate. Is supported on a concave surface having an arcuate cross section formed on the upper side of a cylindrical holding member, the holding member is supported on an upper end surface of a holding cylinder screwed to a skirt portion, and the flat surface of the piston crown portion is supported. An inlet passage formed between the periphery and the peripheral wall of the piston to be closed by the presser member and supplying lubricating oil from an oil jet disposed at a lower end of the cylinder to the annular space; An outlet passage for returning the empty oil to the skirt, and It is characterized by being arranged at intervals.

Further, the configuration of the present invention engages a convex surface having a circular cross section formed at the lower central portion of the piston crown with a concave surface having a circular cross section formed above a receiving plate provided at the tip of the connecting rod, An upper end surface of a holding cylinder in which a convex surface having a circular cross section formed on the lower side of the receiving plate is supported by a concave surface having a circular cross section formed on the upper side of a cylindrical holding member, and the pressing member is screwed to a skirt portion. And an annular space closed by the pressing member is formed between the lower periphery of the piston crown and the peripheral wall of the piston, and lubricating oil from an oil jet disposed at the lower end of the cylinder is formed in the annular space. An inlet passage for supplying to the empty space and an outlet passage for returning the oil of the annular empty space to the skirt portion are arranged at intervals in the circumferential direction in the pressing member.

[Operation] The annular space between the wall portion of the piston crown section that defines the combustion chamber and the peripheral wall of the piston is closed by a pressing member that supports the lower convex 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 ejected from an oil jet provided at the lower end of the cylinder is introduced into the annular space from the inlet passage, and flows through the annular space to form a combustion chamber. The surroundings are cooled and returned from the outlet passage to the skirt. Therefore,
The thermal load on the piston peripheral wall is reduced, and seizure of the piston ring is prevented. The oil in the annular space also cools the sliding part between the piston crown and the sliding body and the sliding part between the sliding body and the receiving plate of the connecting rod, so that the sliding part is prevented from seizing.

FIG. 1 is a front sectional view of a connecting structure of a piston and a connecting rod according to the present invention. The piston 2 for the diesel engine is
A well-known depression 3 as a combustion chamber is formed on the upper side of the crown 2a, a plurality of annular grooves for mounting a piston ring are formed on the peripheral wall, and a cylindrical skirt 7 is formed on the lower half.
An annular space 6 is defined between the lower central portion 4 of the crown 2a and the peripheral wall. A flat upper surface 22 of a sliding body 21 made of a material having excellent wear resistance and thermal conductivity is slidably abutted on the flat lower surface 20 of the crown 2a. On a convex surface (spherical surface) 5 having an arc-shaped cross section formed on the lower side of the sliding body 21, a receiving plate 12 provided at the distal end of the connecting rod 13 is provided.
The concave surface (spherical surface) 12a having an arc-shaped cross section formed on the upper side of the upper surface is slidably engaged.

A passage 24 is provided at the center of the slide 21, and 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, which preferably has a cutout in the center of the convex surface 5. . Lubricating oil is recessed from the internal passage 26 of the connecting rod 13
Supplied to The lubricating oil lubricates a sliding portion between the upper surface 22 and the lower surface 20 and a sliding portion between the concave surface 12a and the convex surface 5.

An arc-shaped convex surface (spherical surface) 12 formed below the receiving plate 12
b is slidably supported by a concave surface (spherical surface) 8a formed on the upper side of the cylindrical pressing member 8 and having an arc-shaped cross section. Presser member 8
For the sake of assembling, for example, a two-piece body is combined, and is slidably supported on the upper end surface of the holding cylinder 9 within a small range. The holding tube 9 is screwed to the skirt portion 7 and fastened by a locking nut 10 so as not to be loosened. The configuration of the lower end of the connecting rod 13 is the same as that of the conventional one, but in the present invention, lubricating oil pressurized and supplied from the oil pump to one end of the crankshaft is supplied to each of the crankshaft, the crank arm, and the crankpin. It is supplied to the internal passage 26 of the connecting rod 13 via the internal passage.

According to the present invention, the inlet passage is provided to the holding member 8 for guiding the lubricating oil supplied from the oil pump to the oil jet 52 disposed at the lower end of the cylinder under pressure to the annular space 6 of the piston crown 2a. 43 and an outlet passage 44 are arranged at intervals in the circumferential direction. In order to effectively cool the upper portion of the annular space 6, an annular partition plate 42 having an inverted U-shaped cross section is disposed in the annular space 6.

As shown in FIG. 3, the inlet of the annular space 6 is used to guide oil from the inlet hole 49 of the partition plate 42 to the annular space 6 and to separate the oil in the opposite directions and flow to the outlet hole 50. Passage 43,
Specifically, a flow dividing wall 41 having an inverted triangular cross section is projected downward from the top wall of the annular space 6 at a portion of the partition plate 42 facing the entrance hole 49.

As shown in FIG. 1, the edge 42a of the partition plate 42 is curved downward, and is elastically engaged with the peripheral wall of the lower central portion 4 of the piston crown 2a, that is, the inner peripheral wall 6a of the annular space 6. Is done. The edge 42b of the partition plate 42 is elastically engaged with the outer peripheral wall 6b of the annular space 6. An outlet hole 50 is provided at an edge 42b of the partition plate 42 so as to face the outlet passage 44.

According to the present invention, the oil jetted from the oil jet 52 disposed at the lower end of the cylinder is supplied to the inlet passage 43 of the holding member 8,
Through the inlet hole 49 of the partition plate 42, it hits the distribution wall 41 of the annular space 6, is divided into left and right sides, and flows into the annular space 6. The oil that has made a half turn around the annular space 6 above the partition plate 42 cools the piston crown 2a, especially the peripheral wall of the recess 3 as a combustion chamber, and the annular space between the partition plate 42 and the holding member 8 from the outlet hole 50. It flows to the empty space, and further flows down to the crank chamber via the outlet passage 44 of the holding member 8.

On the top wall of the annular space 6 facing the inlet passage 43 of the holding member 8, there is an inverted triangular distribution wall 41, so that the oil from the oil jet 52 is divided into two directions and flows evenly to the annular space 6. Also in this respect, the cooling capacity is improved.

If the partition plate 42 is inclined downward from the inlet hole 49 toward the outlet hole 50 (by inclining the plate surface of the partition plate 42 with respect to the piston top surface), the oil flow is improved and the cooling effect is further improved. Be improved.

Further, according to the present invention, in order to guide the oil scraped off from the inner peripheral surface of the cylinder by the oil scraping ring of the piston 2 to the inside of the skirt portion 7, a small diameter portion is provided below the oil scraping ring groove of the skirt portion 7. 51 are formed. A large number of inclined passages 45 are provided in the small diameter portion 51 at intervals in the circumferential direction. Inclined passage 45
Is communicated with an annular groove 46 formed on the outer peripheral surface of the holding cylinder 9 and further with a number of passages 47 (see FIG. 2) penetrating the holding cylinder 9. Accordingly, the oil scraped off from the inner peripheral surface of the cylinder by the oil scraping ring flows down along the small diameter portion 51 and flows down to the crank chamber via the inclined passage 45, the annular groove 46, and the passage 47.

In the above-described embodiment, the convex surfaces 5, 12b and the concave surfaces 12a, 8a are spherical, but the convex surfaces 5, 12b are formed into ridges having an arc-shaped cross section, and the concave surface 1 is formed.
The grooves 2a and 8a may be grooves having an arc-shaped cross section (both have a uniform cross section in a direction perpendicular to the plane of the drawing).

Further, as a modified embodiment of the present invention, the sliding body 21 may be formed integrally with the piston crown 2a without providing the sliding body 21. That is, as illustrated in FIG. 4, the convex surface 5 may be formed directly on the lower central portion 4 of the crown portion 2a.

[Effects of the Invention] As described above, the present invention provides an arc-shaped convex surface formed on the lower central part of the piston crown or on the lower side of the sliding body on the upper side of the receiving plate provided at the tip of the connecting rod. Engaging with the concave surface of the formed circular cross section, supporting the convex surface of the circular cross section formed on the lower side of the receiving plate on the concave surface of the circular cross section formed on the upper side of the cylindrical pressing member; Is supported on the upper end surface of the holding cylinder screwed to the skirt portion, and an annular space closed by the pressing member is formed between the periphery of the flat surface of the piston crown and the peripheral wall of the piston, and the lower end portion of the cylinder is formed. An inlet passage for supplying lubricating oil from an oil jet provided to the annular space to the annular space and an outlet passage for returning oil from the annular space to the skirt portion are provided at intervals in the circumferential direction of the holding member. It is a button that supports the piston pin like a conventional piston. Since there is no space portion, at least one inlet passage for guiding oil from the oil jet to the annular space can be arranged at an arbitrary circumferential position, and the cooling capacity can be improved.

Since there is no boss that supports the piston pin as in the conventional piston, a large-capacity annular space can be formed between the lower central part of the piston crown and the piston peripheral wall, and the peripheral wall of the combustion chamber and the piston peripheral wall can be formed. (Ring land) can be cooled effectively.

[Brief description of the 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 bottom view thereof, FIG. 3 is a side sectional view near an inlet hole of an annular space, and FIG. FIG. 5 is a front sectional view showing a connecting structure of a piston and a connecting rod to which the invention is applied, and FIG. 5 is a side sectional view of the same. 2: piston, 2a: crown, 5, 12b: convex, 6: annular space, 7: skirt, 8: holding member, 8a, 12a: concave, 12: receiving plate, 13: connecting rod, 21: sliding Moving body, 43: Inlet passage, 44: Outlet passage, 52: Oil jet

Claims (2)

(57) [Claims] 1. A flat upper surface of a sliding body is brought into contact with a flat surface formed at a lower central portion of a piston crown, and an arc-shaped convex surface formed on a lower side of the sliding body is connected to a tip of a connecting rod. Engages with the concave surface of the circular cross section formed on the upper side of the receiving plate provided in the portion, and the convex surface of the circular cross section formed on the lower side of the receiving plate is formed in the circular cross section formed on the upper side of the cylindrical pressing member. Supported on the concave surface of
The holding member is supported on an upper end surface of a holding cylinder screwed to the skirt portion, and an annular space closed by the holding member is formed between the periphery of the flat surface of the piston crown and the peripheral wall of the piston. An inlet passage for supplying lubricating oil from an oil jet, which is provided at a lower end of the oil jet, to the annular space, and an outlet passage for returning oil from the annular space to the skirt portion are provided at intervals in the circumferential direction of the pressing member. The connecting structure of the piston and the connecting rod, characterized in that it is arranged and installed. 2. The receiving device according to claim 1, wherein the convex surface having an arcuate cross section formed at the lower central portion of the piston crown is engaged with a concave surface having an arcuate cross section formed above a receiving plate provided at the tip of the connecting rod. An arc-shaped convex surface formed on the lower side of the plate is supported by an arc-shaped concave surface formed on the upper side of the cylindrical pressing member, and the pressing member is supported on an upper end surface of a holding cylinder screwed into a skirt portion. An annular space closed by the pressing member is formed between the lower periphery of the piston crown and the peripheral wall of the piston, and lubricating oil from an oil jet disposed at a lower end of the cylinder is supplied to the annular space. A piston and a connecting rod, wherein an inlet passage for supplying oil to the annular space and an outlet passage for returning oil in the annular space to the skirt portion are arranged at intervals in the circumferential direction of the pressing member. Construction.