JP2833179B2 - Connection structure of piston and connecting rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement in a connection structure between a piston and a connecting rod, which facilitates machining of a sliding surface and has excellent lubricity.

[Prior Art] As shown in FIGS. 2 and 3, the present applicant has previously filed Japanese Patent Application No. 2-856.
According to No. 63, the arc-shaped convex surface 5 formed on the lower convex portion 4 of the piston crown 2a is connected to the arc-shaped concave surface 12a on the upper side of the receiving plate 12 formed at the tip of the connecting rod 13. Then, the lower convex surface 12b of the circular cross section on the lower side of the receiving plate 12 is engaged with the concave surface 8a on the upper circular cross section of the annular pressing member 8, and the annular pressing member 8 is attached to the skirt portion 7 of the piston 2. We have applied for a connection structure between a piston and a connecting rod, which is supported by a screwed holding cylinder 9.

The above-described connection structure between the piston and the connecting rod has the following advantages as compared with the connection structure using a conventional piston pin. That is, when the sliding 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 1 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 displacement is increased, the waste volume at the top dead center of the piston 2 is reduced, and the measures against exhaust gas become easy. Piston 2
Even if the stroke increases, the maximum inclination angle of the connecting rod 13 does not increase, so that there are no problems such as piston slap, accompanying friction loss, piston ring wear, 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.

However, in the connection structure of the piston and the connecting rod described above,
The convex portion 4 on the lower side of the piston crown 2a, the convex surfaces 5, 12b having an arc-shaped cross section provided on the lower surface of the receiving plate 12, the upper surface of the receiving plate 12, and the pressing member 8
Concentricity is required with the concave surfaces 12a and 8a having an arc-shaped cross section provided on the upper surface of the device, and it takes time and effort to machine.

[Problems to be Solved by the Invention] An object of the present invention is to provide a connecting structure of a piston and a connecting rod which is easy to machine and does not impair the above advantages in view of the above problems.

To achieve the above object, the configuration of the present invention abuts the sliding plate on the lower surface of the piston crown so as to be slidable in the lateral direction, and forms a convex surface having an arc-shaped cross section formed on the lower edge of the sliding plate, Supporting on the concave surface with a circular cross section formed on the upper side of the receiving plate at the tip of the connecting rod,
An arc-shaped convex surface formed on the lower side of the receiving plate is supported by a convex surface on the circular arc formed on the upper edge of the annular pressing member,
The holding member is supported on the holding cylinder screwed to the skirt so as to be slidable in the lateral direction.

[Operation] The convex surface on the cross-sectional arc processed on the lower edge of the sliding plate and the convex surface on the circular arc cross-section processed on the upper edge of the holding member need not be concentric with the concave surface or convex surface of the receiving plate. Therefore, machining is simplified and costs are reduced.

The arc-shaped convex surface of the sliding plate and the arc-shaped convex surface of the holding member sandwich the receiving plate in a line contact state, and guide the connecting rod to swing with respect to the piston.

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 of the crown portion 2a is formed, and a plurality of annular grooves for mounting a piston ring are formed on the peripheral wall,
A cylindrical skirt 7 is formed in the lower half. A convex portion 4 is formed at the lower center of the crown 2a, and an annular space 6 is defined between the convex portion 4 and the peripheral wall. An upper surface 22 of a sliding plate 21 made of a material having excellent wear resistance and heat conductivity is provided on a flat lower surface 20 of the crown portion 2a.
Are slidably contacted.

An arc-shaped convex surface formed on the lower edge of the sliding plate 21 is
The connecting rod 13 is slidably supported by the spherical concave surface 12a on the upper side of the receiving plate 12 formed at the tip of the connecting rod 13. Center of curvature O1 of convex surface 5
(FIG. 2) is above the sliding plate 21 and the radius of curvature is
Twelve concave surfaces 12a are smaller than the radius of curvature.

A passage 24 is provided at the center of the sliding plate 21, and an upper end of the passage 24 is communicated with a recess 23 of the upper surface 22. Lubricating oil is supplied from the internal passage 26 of the connecting rod 13 to the space 25 between the sliding plate 21 and the concave surface 12a. 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.

The spherical convex surface 12b formed on the lower side of the receiving plate 12 is slidably supported by an arc-shaped convex surface 8b at the upper edge of the annular pressing member 8. The center of curvature O2 (FIG. 2) of the convex surface 8b is located on the outer peripheral side below the holding member 8, and is preferably on an extension of a straight line connecting the swing center O and the center of curvature O1. In the illustrated embodiment, since the concave surface 12a and the convex surface 12b of the receiving plate 12 are spherical, the sliding plate 21 and the pressing member 8 are configured as a rotating body about the central axis y of the piston 2. Presser member 8
For the sake of assembly, for example, a two-piece body is combined, and is supported on the upper surface of the holding cylinder 9 so as to be slidable in the lateral direction within a small range. The holding tube 9 is screwed to the skirt portion 7 and fastened so as not to be loosened from the locknut 10.

The configuration of the lower end of the connecting rod 13 is the same as that of the conventional one, but in the illustrated embodiment, the lubricating oil pressurized and supplied from the oil pump to one end of the crankshaft is supplied to the crankshaft, the crank arm, and the crankshaft. It is supplied to the internal passage 26 of the connecting rod 13 via each internal passage of the pin.

Oil jet 52 installed at the lower end of cylinder from oil pump
In order to guide the lubricating oil supplied under pressure to the annular space 6 of the piston crown 2a, the pressing member 8 has an inlet passage 43 and an outlet passage 44.
Are arranged at intervals in the circumferential direction. An annular partition plate 42 having an inverted U-shaped cross section is disposed in the annular space 6. Divider 42
Of the annular space 6 is elastically engaged with the inner peripheral wall 6a. The edge 42b of the partition plate 42 is elastically engaged with the outer peripheral wall 6b of the annular space 6. An inlet hole is provided at a portion of the partition plate 42 that faces the inlet passage 43, and an outlet hole is provided at a portion that faces the outlet passage 44.

A small diameter portion 51 is formed below the oil scraping ring groove of the skirt portion 7 to guide the oil scraped from the inner peripheral wall of the cylinder by the oil scraping ring on the lower side of the piston 2 to the inside of the skirt portion 7. A large number of inclined passages 45 are provided in the skirt 7 at intervals in the circumferential direction. The inclined passage 45 communicates with an annular groove 46 formed in the inner peripheral wall of the skirt portion 7, and further communicates with a number of passages 47 provided in the holding cylinder 9.

When the connecting rod 13 swings with the reciprocation of the piston 2, the concave surface 12 a and the convex surface 12 b of the receiving plate 12 slide in linear contact with the convex surface 5 of the sliding plate 21 and the convex surface 8 b of the pressing member 8. Move. Backing plate
The sliding portion between the sliding plate 12 and the sliding plate 21 is lubricated with the lubricating oil from the annular space 6 and the lubricating oil from the internal passage 26. The sliding portion between the receiving plate 12 and the holding member 8 is lubricated by the lubricating oil from the annular space 6.

When the piston 2 tilts (oscillates) about the swing center O and the piston 2 hits one side of the cylinder inner peripheral surface,
Lateral sliding (parallel movement) occurs between the sliding plate 21 and the convex portion 4 of the piston 2 and between the holding cylinder 9 and the pressing member 8, and the outer peripheral surface of the piston 2 from the upper end to the lower end forms a cylinder. Sliding contact with the inner peripheral surface.

The oil jetted from the oil jet 52 provided at the lower end of the cylinder passes through the entrance passage 43 of the holding member 8 and the entrance hole of the partition plate 42, enters the annular space 6 above the partition plate 42, and is divided into right and left. During the half-circle around the annular space 6 by cooling, the peripheral wall of the depression 3 as a combustion chamber is cooled, and the annular space 6 below the partition plate 42 is cooled from the outlet hole.
To the crank chamber via the outlet passage 44 of the holding member 8.

In the above-described embodiment, the concave surface 12a and the convex surface 12b are spherical. ,
Correspondingly, the slide plate 21 is provided with a ridge having a pair of convex surfaces 5 having a uniform cross section, and the pressing member 8 is provided with a concave groove having a pair of convex surfaces 8b having a uniform cross section.

[Effects of the Invention] As described above, the present invention abuts the sliding plate on the lower surface of the piston crown so as to be slidable in the lateral direction, and forms a convex surface having an arc-shaped cross section formed on the lower edge of the sliding plate, The connecting rod tip is supported by an arc-shaped concave surface formed on the upper side of the receiving plate, and the arc-shaped convex surface formed on the lower side of the receiving plate is formed by an arc-shaped cross-section formed on the upper edge of the annular holding member. The holding member is supported on the holding cylinder screwed into the skirt portion so as to be slidable in the horizontal direction. The convex surface is formed on the lower side of the sliding plate and the convex surface is formed on the upper side of the pressing member. Need not be processed concentrically with the concave and convex surfaces of the receiving plate, so that machining becomes easy.

A cross section between the arc-shaped convex surface of the lower edge of the sliding plate and the concave arc-shaped cross section on the upper side of the receiving plate, and a cross-section of the arc-shaped convex surface on the lower side of the receiving plate and the upper edge of the holding member. Oil flows easily between the arc-shaped convex surfaces, and lubricity is improved.

Although the respective contact areas of the receiving plate and the sliding plate and the pressing member and the receiving plate are reduced, when the two slide relative to each other, the oil film well penetrates between the two due to the squeeze effect, and the load capacity of the oil film is improved.

Since the outer peripheral surface of the piston contacts the inner peripheral surface of the cylinder in the region from the upper end to the lower end of the piston due to the lateral relative sliding of the piston crown and the sliding plate, and the holding cylinder and the holding member, the piston tilts (oscillates). Movement), the sliding resistance of the piston corresponding to the cylinder is reduced, and fuel efficiency is improved.

[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 front sectional view showing a convex surface of the same structure, and FIG. 3 shows a conventional connecting structure of a piston and a connecting rod. FIG. 4 is a front sectional view, and FIG. 2: piston, 2a: crown, 5, 8b: convex, 7: skirt, 8: holding member, 9: holding cylinder, 12: receiving plate, 12a: concave, 12b: convex, 13:
Connecting rod, 21: sliding plate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02F 3/00 F02F 3/00 301 F16J 1/22 F16C 7/02

Claims (1)

(57) [Claims] 1. A sliding plate is slidably abutted on the lower surface of a piston crown portion in a laterally slidable manner, and a convex surface having an arc-shaped cross section formed on a lower edge portion of the sliding plate is provided on a receiving plate at a tip end of a connecting rod. The skirt portion is supported by an arc-shaped concave surface formed on the upper side, and the arc-shaped convex surface formed on the lower side of the receiving plate is supported by a convex surface on the arc formed on the upper edge of the annular holding member. A connecting structure for connecting a piston and a connecting rod, wherein a holding member is supported on a holding cylinder screwed into the connecting cylinder so as to be slidable in the lateral direction.