JPH07243348A - Piston for internal combustion engine - Google Patents

Abstract

PURPOSE:To optimize shapes of pin holes and pin hole fitting parts of piston pins against deformation of the piston pins so as to prevent local abutting on the holes of piston pins and always receive load by the whole length of bearings of the pin holes. CONSTITUTION:Metal bush caps 4, 4 are fitted into a part of pin holes 2, 2 provided in a piston main body 1, inside diameters of the metal bush caps 4, 4 and the pin holes 2, 2 are formed into arc shapes continuing each other, metal bushes 5, 5 are fitted in pin hole engagement parts 3a, 3a of piston pins 3, which are engaged with the metal bush caps 4, 4 and the pin holes 2, 2, and outside diameters of the metal bushes 5, 5 are formed into arc shapes so as to be fitted into the inside diameter of the metal bush caps 4, 4 and the pin holes 2, 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in internal combustion engine pistons used in automobiles and the like.

[0002]

2. Description of the Related Art In a conventional piston for an internal combustion engine, as described in, for example, Japanese Utility Model Laid-Open No. 61-82053, the inner diameter of a pin hole provided in the piston body is changed from the central portion of the pin hole to the piston body. The taper shape gradually increases toward both the inner side and the outer side of the pin hole to avoid the local deformation of the inner and outer ends of the pin hole against bending deformation of the piston pin fitted in the pin hole. Was intended.

[0003]

However, in such a conventional piston for an internal combustion engine, since the pin hole has a tapered shape which gradually increases from the central portion toward both the inside and the outside of the piston body. The pin hole has a shape that swells inward at the central portion, and it becomes impossible to support the piston pin over the entire length of the pin hole.
Therefore, the pin hole reduces the pressure receiving area for the piston pin, which may result in a substantial increase in the piston pin surface pressure as a whole. Also, if the taper angles on the inside and outside of the pin hole inner diameter and the shape when the piston pin is deformed are not optimized, this surface may warp and may cause local contact with the pin hole of the piston pin. .

In view of this point, the present invention makes the pin hole and the pin hole fitting portion of the piston pin have an optimum shape with respect to the deformation of the piston pin to prevent the piston pin from locally hitting the pin hole. At the same time, it is an object of the present invention to provide a piston for an internal combustion engine that always receives a load over the entire bearing length of the pin hole.

[0005]

A piston for an internal combustion engine according to the present invention is, firstly, a piston pin which is formed in an inner diameter of a pin hole provided in a piston body in an arc shape and is fitted into the pin hole. Fit a metal bush into the pin hole fitting part of
The outer diameter of the metal bush is formed in an arc shape that matches the inner diameter of the pin hole.

Secondly, a metal bush cap is fitted in the pin hole provided in the piston body, the inner diameter of the metal bush cap is formed in an arc shape, and the metal bush fitted in the pin hole fitting portion of the piston pin. Is formed in an arc shape that matches the arc-shaped inner diameter of the bush cap.

Thirdly, a metal bush cap is fitted in a part of the pin hole provided in the piston main body, and the inner diameters of the metal bush cap and the pin hole are formed in a continuous arc shape, and the metal bush cap is formed. Also, a metal bush is fitted in the pin hole fitting portion of the piston pin fitted in the pin hole, and the outer diameter of the metal bush is formed in an arc shape that matches the inner diameters of the metal bush cap and the pin hole.

[0008]

[Operation] When the piston pin is deformed by the bending moment caused by the operation of the internal combustion engine, the piston pin slides within the inner diameter of the pin hole or the metal bush cap, and the arc-shaped outer diameter of the metal bush and the pin hole or the metal bush cap. The entire arc-shaped inner diameter of the pin receives the pin hole fitting portion of the piston pin, which prevents local contact of the piston pin.

Further, the outer diameter of the metal bush and the inner diameter of the pin hole or the metal bush cap are formed in an arc shape which fits each other, so that the optimum shape of the pin hole can be obtained with respect to the deformation of the piston pin.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical cross-sectional view of a piston according to an embodiment of the present invention, in which reference numeral 1 denotes a piston body, which is provided with a pair of pin holes 2 and 2 on both sides thereof. Has been. Metal bush caps 6 and 6 are fitted on the outer sides of the pin holes 2 and 2, respectively. Then, the inner diameters 6a, 6 of the metal bush caps 6, 6
a and inner diameters 2a, 2a inside the pin holes 2, 2 are formed in a concave arc shape which is continuous with each other and bulges toward the piston body 1 side at the central portion.

Reference numeral 3 denotes a piston pin whose both outer portions are fitted into the pin holes 2 and 2 to support a connecting rod (not shown), and the piston pin 3 is formed of a hollow body. , Pin hole fitting portions 3 on both outer sides thereof
Metal bushes 5 and 5 are fitted in a and 3a. The outer diameters 5a and 5a of the metal bushes 5 and 5 are convex arc shapes that conform to the concave arc shapes formed on the inner diameters 6a and 6a of the metal bush caps 6 and 6 and the inner diameters 2a and 2a inside the pin holes 2. Is formed in. The outer ends of the metal bushes 5 and 5 are crimped 5b and 5b on both ends of the piston pin 3, respectively.

Reference numerals 4 and 4 are snap rings for preventing the metal bushes 5 and 5 and the metal bush caps 6 and 6 from coming off from the pin holes 2 and 2. The snap rings 4 and 4 are
It is inserted into a ring groove provided at the outer ends of the pin holes 2 and 2.

Further, the piston pin and the metal bush are assembled to the piston body with a snap ring and a metal bush cap so that they can be easily assembled and disassembled.

According to the embodiment of the present invention configured as described above, when the internal combustion engine is operating, for example, in the compression / explosion stroke, as shown in FIG. 2, the piston pin 3 has the center line P of the piston body 1. The inner diameter of the convex arcs of the metal bushes 5 and 5 fitted on both outer sides is the inner diameter of the concave arcs of the pin holes 2 and 2 and the metal bush caps 6 and 6. By rotating and sliding on the top, local contact of the piston pin is prevented, and the load is always received by the entire bearing length of the pin holes 2 and 2 and the metal bush caps 6 and 6.

Further, in the exhaust / intake stroke shown in FIG. 3, the piston pin 3 is deformed in a convex shape downward with the center line P of the piston body 1 as a center. The convex arcuate inner diameter of 5 slides on the pinholes 2 and 2 and the concave arcuate inner diameters of the metal bush caps 6 and 6 to prevent the piston pin from locally hitting, so that the pinholes 2 and 2 and the metal are always supported. The entire bearing length of the bush caps 6 and 6 receives the load.

FIG. 4 shows another embodiment of the present invention, in which the metal bush cap 6 extends over the entire length of the pin hole 2.
The inner diameter 6c of the metal bush cap 6 is formed in a concave arc shape so as to match the convex arc outer diameter of the metal bush 5.

The metal bush 5 or the metal bush cap 6 in the embodiment of FIG. 4 is of a split type from the center to the left and right in order to easily fit into the pin hole 2.

[0019]

According to the piston for an internal combustion engine having the above structure, firstly, the inner diameter of the pin hole provided in the piston body is formed in an arc shape, and the pin of the piston pin fitted into the pin hole is formed. A metal bush is fitted in the hole fitting portion, and the outer diameter of the metal bush is formed in an arc shape that matches the inner diameter of the pin hole. Secondly, the metal is inserted in the pin hole provided in the piston body. The bush cap is fitted to form the inner diameter of the metal bush cap in an arc shape, and the metal bush fitted to the pin hole fitting portion of the piston pin is formed in an arc shape that matches the arc inner diameter of the bush cap. Thirdly, a metal bush cap is fitted in a part of the pin hole provided in the piston body, and the inner diameters of the metal bush cap and the pin hole are continuous with each other. A metal bush is formed in an arc shape, and a metal bush is fitted in a pin hole fitting portion of a piston pin that fits in the metal bush cap and the pin hole, and the outer diameter of the metal bush matches the inner diameter of the metal bush cap and the pin hole. Since the piston pin is formed in an arc shape, when the piston pin receives a bending moment and deforms due to the operation of the internal combustion engine, the outer diameter of the metal bush fitted on the piston pin slides within the pin hole or the inner diameter of the metal bush cap. The outer diameter of the metal bush and the pin hole or the entire inner diameter of the metal bush cap receives the pin hole fitting portion of the piston pin, which prevents local contact of the piston pin and prevents the piston pin and pin hole. It is possible to effectively prevent pin scuffing and stress concentration due to oil film breakage between and.

Further, since the outer diameter of the metal bush and the inner diameter of the pin hole or the metal bush cap are formed in an arc shape which fits each other, it is easy to obtain the optimum shape of the pin hole for the deformation of the piston pin. As a result, the surface pressure limit between the piston pin and the pin hole can be further increased, and the weight of the piston and the piston pin can be further reduced.

The piston pin and the metal bush are assembled to the piston body by the snap ring and the metal bush cap. If the snap ring and the metal bush cap are removed, the piston pin and the metal bush are attached to the piston body. Since it can be disassembled, it is easy to disassemble and assemble the piston pin and the metal bush with respect to the piston body.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a piston according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the same piston as FIG. 1 for explaining the deformation of the piston pin during the compression / explosion stroke of the internal combustion engine.

FIG. 3 is a vertical cross-sectional view of the same piston as FIG. 1 for explaining the deformation of the piston pin during the intake / exhaust stroke of the internal combustion engine.

FIG. 4 is a vertical cross-sectional view of a piston according to another embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view of a piston according to still another embodiment of the present invention.

[Explanation of symbols]

 1 Piston body 2 Pin hole 2a, 2c Pin hole inner diameter 3 Piston pin 5 Metal bush 5a Metal bush outer diameter 6 Metal bush cap 6a, 6c Metal bush cap 6 inner diameter

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[Procedure amendment]

[Submission date] July 1, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 5

[Correction method] Delete

Claims (4)

[Claims] 1. An inner diameter of a pin hole provided in a piston main body is formed in an arc shape, and a metal bush is fitted to a pin hole fitting portion of a piston pin fitted in the pin hole. A piston for an internal combustion engine, the outer diameter of which is formed in an arc shape that matches the inner diameter of the pin hole. 2. A metal bush cap is fitted into a pin hole provided in a piston body, an inner diameter of the metal bush cap is formed in an arc shape, and a pin hole fitting of a piston pin fitted into the metal bush cap is fitted. A piston for an internal combustion engine, characterized in that a metal bush is fitted in the portion, and the outer diameter of the metal bush is formed in an arc shape that matches the inner diameter of the metal bush cap. 3. A metal bush cap is fitted in a part of a pin hole provided in the piston main body, and inner diameters of the metal bush cap and the pin hole are formed in a continuous arc shape, and the metal bush cap and the pin are formed. An internal combustion engine, characterized in that a metal bush is fitted in a pin hole fitting portion of a piston pin fitted in the hole, and an outer diameter of the metal bush is formed in an arc shape matching the inner diameters of the metal bush cap and the pin hole. For piston. 4. The piston for an internal combustion engine according to claim 2, wherein the piston pin and the metal bush are assembled to the piston body with a snap ring and a metal bush cap.