JPH04109064A - Connecting structure between piston and connecting rod - Google Patents

Abstract

PURPOSE:To suppress local abrasion by lightening lateral load, acting upon the oscillating center of a piston in association with the reciprocating motion of a piston and the oscillation of a connecting rod, by relative sliding resistance between a piston crown part and a sliding body for supporting the connecting rod oscillatingly. CONSTITUTION:A piston 2 for an diesel engine is provided with a recess 3 serving as a combustion chamber formed in a crown part 2a. In this case, the flat upper face 22 of a sliding body 21 made of material excellent in wear resistance and heat conductivity is brought into slidable contact with the flat lower face 20 of the crown part 2a. 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 8. The keep 8 is supported on the upper face of a holding cylinder 9 in such a way as to be slidable within the range of a clearance (c), and the holding cylinder 9 is screwed with a skirt part 7 and fastened by a lock nut 10.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a piston and connecting rod connection structure that alleviates the lateral load generated at the center of piston oscillation due to the reciprocating movement of the piston and the oscillation of the connecting rod. This is related to the improvement of.

[Prior Art] As shown in Figure 4.5, the present applicant previously filed Japanese Patent Application No. 2-8
According to No. 5663, a bowl-shaped receiving plate 1 is formed at the tip of the connecting rod 13 on the convex surface 5 formed on the lower surface of the piston crown 2a.
2 and the lower surface of the receiving plate 12 is supported by a holding cylinder 9 screwed onto the skirt portion 7 of the 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, the pivot center 0 of the connecting rod 13 is biased toward the piston crown 2a, and the crankshaft 16 is shifted by the amount of the bias.
By increasing the arm length r and the length 1 of the connecting rod 13, the stroke of the piston 2 is increased without increasing the maximum tilt angle (l movement angle) of the connecting rod 13. By increasing the stroke of the piston 2, the displacement is increased, and the wasted volume at the top dead center of the piston 2 is reduced, making it 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 there are no problems such as piston slap, associated 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.

Not only the above-mentioned connection structure between the piston and the connecting rod, but also a structure in which the connecting rod 13 is connected to the piston 2 by a piston pin 32 as shown in FIG. As a result, a lateral load acts on the pivot center of the piston 2. For example, when the piston 2 is pushed up by the connecting rod 13, the thrust F in the longitudinal direction of the connecting rod 13
is the component force F1 perpendicular to the top surface of the piston 2, and the component force F1 perpendicular to the top surface of the piston 2
A component force (lateral load>F2) parallel to the top surface of the piston 2 is exerted.The lateral load F2 acting on the swing center O of the piston 2 causes the piston peripheral wall (ring land) to strongly collide with the cylinder inner peripheral wall, causing local damage to the piston peripheral wall. This causes wear, local wear on the inner peripheral wall of the cylinder, wear on the piston rings, etc.

[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 that alleviates the lateral load acting on the piston through relative sliding between the tip of the connecting rod and the piston crown. and the connecting structure of the connecting rod.

[Means for Solving the Problem 1] In order to achieve the above object, the configuration of the present invention is such that a convex surface having an arcuate cross section is provided on the lower surface of the sliding body that is slidably engaged with the lower surface of the piston crown. A receiving plate having a uniform thickness and having a concave surface with an arcuate cross section that engages with the convex surface is integrally formed at the tip of the connecting rod, and a retainer having a concave surface with an arcuate cross section that engages with the lower surface of the receiving plate is attached to the piston. It is supported so as to be able to slide laterally on a holding cylinder screwed into the skirt part.

[Function] According to the present invention, the lateral load that acts on the pivot center of the piston due to the reciprocating motion of the piston and the pivoting of the connecting rod is absorbed by the sliding body that swingably supports the piston crown and the connecting rod. This is alleviated by the slight relative sliding resistance of the flywheel, and local wear of the cylinder, piston, piston ring, etc. due to collision between the piston circumferential wall and the cylinder inner circumferential wall is suppressed.

[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 convex portion 4 that protrudes downward is formed at the center of the convex portion 4, and an annular cavity 6 is defined between the convex portion 4 and the peripheral wall. A flat upper surface 22 of a WWJ body 21 made of a material with excellent wear resistance and thermal conductivity is slidably abutted on the flat lower surface 20 of the crown portion 2a. A spherical convex surface 5 formed on the lower surface of the sliding body 21 and a spherical concave surface 1 of the receiving plate 12 formed on the tip of the connecting rod 13.
2a is 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 lower surface 20 and the upper surface 22, and also lubricates the sliding parts between the concave surface 12a and the convex surface 5.
ms of the sliding part.

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 presser foot 8. For convenience of assembly, the presser foot 8 is formed by combining two parts, for example, and is slidably supported on the upper surface of the holding cylinder 9 within a gap C. The holding cylinder 9 is screwed into the skirt part 7,
And it is 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, lubricating oil supplied under pressure from one end of the crankshaft flows through each internal passage of the crankshaft, crank arm, and crank pin. It is then fed into the internal passage 26 of the connecting rod 13.

Lubricating oil is injected into the skirt portion 7 of the piston 2 from a known nozzle arranged on the cylinder wall and is supplied to the annular cavity 6 through a passage (not shown) provided in the presser foot 8.

The piston 2 is pushed down by the explosive load P acting on the top surface of the piston 2. As the piston 2 reciprocates, the connecting rod 13 moves toward the center of oscillation 0 (the concave surface 12a) as shown by the broken line.
When the explosive load P exerts a longitudinal force P1 on the connecting rod 13 and a transverse force P2 on the piston 2. Conversely, when the piston 2 is pushed up by the connecting rod 13, the longitudinal force acting on the piston 2 from the connecting rod 13 is divided into a force pushing the piston 2 upwards and a force pushing the piston 2 laterally. affect

Due to the lateral load acting on the piston 2, relative sliding occurs between the upper surface 22 of the sliding body 21 and the lower surface 20 of the piston 2,
At the same time, relative sliding occurs between the lower surface of the presser foot 8 and the upper surface of the holding cylinder 9. Due to the viscous resistance of the oil that lubricates each sliding portion, the impact load of the piston peripheral wall to the cylinder inner peripheral wall due to the lateral movement of the piston 2 is alleviated. The lateral load on the piston 2 is caused by the fact that the circumferential wall from the upper end to the lower end of the piston 2 is on the inner circumferential wall of the cylinder.
Since they abut against each other, local wear of the piston circumference W (ring land) and piston rings can be suppressed.

In the embodiment shown in FIG. 2, the lower surface of the piston crown 2a is a concave surface 20a, and correspondingly, the upper surface of the sliding body 21 is a convex surface 22a. In this embodiment, when a lateral load is applied to the piston 2 as the connecting rod 13 swings, the sliding body 21
The posture changes in the dark gap between the convex surface 228 and the concave surface 20a and the gap between the concave surface 12a and the convex surface 5, and as a result, relative sliding occurs between the holding cylinder 9 and the presser foot 8. The oscillating motion of the piston 2 is suppressed, the piston peripheral wall from the upper end to the lower end evenly contacts the cylinder inner peripheral wall, and the lateral load of the piston 2 is supported by the cylinder inner peripheral wall. Since the circumferential wall of the piston from the upper end to the lower end evenly contacts the inner circumferential wall of the cylinder, the surface pressure of the contact portion is small, and the noise of the piston 2 hitting the cylinder is alleviated.

The embodiment shown in FIG. 3 differs from the embodiment shown in FIG. 2 in that a convex surface 20b is formed on the lower surface of the piston crown 2a, and a concave surface 22b is formed on the upper surface of the vibration body 21 correspondingly. 2, and has the same effect as the one shown in FIG.

In addition, in each of the above-mentioned embodiments, the convex surfaces 5 and 12b and the concave surface 12
a and 8a are spherical surfaces, but there are protrusions or grooves with an arcuate cross section (
It may have a --like cross section in the plane of the drawing.

[Effects of the Invention] As described above, the present invention provides a convex surface having an arcuate cross section on the lower surface of the sliding body that is slidably engaged with the lower surface of the piston crown.
A receiving plate of uniform thickness having a concave surface with an arcuate cross section that engages with the convex surface is formed on the tip of the connecting rod, and a presser foot having a concave surface with an arcuate cross section that engages with the lower surface of the receiving plate; Since it is supported so as to be able to slide in the lateral direction on the holding cylinder screwed into the piston skirt part, the following effects are achieved.

(a) The lateral load exerted on the piston by the explosive load or the uplift load of the connecting rod is caused by relative sliding between the piston and the sliding body, and the peripheral wall from the upper end to the lower end of the piston is caused by the internal wall of the cylinder. Since the piston contacts the cylinder, the surface pressure at the contact area between the piston and the cylinder is reduced, the impact of the piston against the cylinder is alleviated, and the piston circumference! ! (Local wear of the ring land and piston rings is suppressed.

(b) The lateral load acting on the piston is stopped by the inner circumferential wall of the cylinder over the entire area from the top end to the bottom end of the piston, so the oscillation movement of the piston is suppressed, and therefore, the oscillation movement of the piston is suppressed. Therefore, there is no need to provide a large gap between the top land of the piston and the inner circumferential wall of the cylinder, as in the conventional case, and waste volume is reduced.

(C) Collision noise between the piston and the cylinder due to lateral loads is reduced.

(d) By reducing the thickness of the M moving body and lengthening the crank arm accordingly, it is possible to increase the displacement of the engine without changing other dimensions.

[Brief explanation of drawings]

FIG. 1 is a front sectional view showing a connection structure between a piston and a connecting rod according to the present invention, FIG. 2.3 is a front sectional view showing a connection structure between a piston and a connecting rod according to a partially modified example of the present invention, FIG. 4 is a front sectional view showing a conventional piston-to-connection rod connection structure, FIG. 5 is a side sectional view of the same, and FIG. 6 is a front sectional view showing the operation of the conventional piston-to-connection rod connection structure. . 2a: Crown portion 5: Convex surface 7: Skirt portion 8: Presser foot 8
a Two concave surfaces 12: Receiving plate 12a Two concave surfaces 12b: Convex surface
21: I! Moving object figure 6

Claims (1)

[Claims] A convex surface with an arcuate cross section is provided on the lower surface of the sliding body that slidably engages with the lower surface of the piston crown, and a receiving plate of uniform thickness and a concave surface with an arcuate cross section that engages with the convex surface is attached to the connecting rod. A presser foot having a concave surface having an arcuate cross section and engaging the lower surface of the receiving plate is integrally formed at the tip of the receiving plate, and is supported so as to be slidable in the lateral direction on a holding cylinder screwed onto the piston skirt. , piston and connecting rod connection structure.