JPH0425535Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a connecting rod for an internal combustion engine using a fiber-reinforced composite material.

[Conventional technology]

In an internal combustion engine, reducing the weight of the reciprocating part of the connecting rod will reduce the inertial weight, which in turn will help reduce the weight of the valve mechanism, reduce the friction of sliding parts, and reduce vibration and noise. For this reason, as disclosed in, for example, Japanese Utility Model Application Publication No. 55-147527 and Japanese Patent Application Publication No. 57-97911, the stem including the large end and the bearing cap are made of synthetic resin or alloy made of glass, carbon, or carbonized resin. It has been proposed to integrally mold a fiber-reinforced composite material reinforced with reinforcing fibers such as silicon.

However, while the connecting rod stem of an internal combustion engine is mainly subjected to simple compression and tension loads due to explosive force and inertia force, the large end of the connecting rod is subjected to repeated bending loads with each revolution of the crankshaft. The bending load causes peeling or cracking between the reinforcing fibers at the big end and the synthetic resin or alloy.

In other words, as shown in FIG. 3, in the conventional connecting rod, due to repeated longitudinal and lateral loads acting on the stem 4, cracks 21 appear in the holes of the bolts 8 that connect the large end 4c and the bearing cap 7. may occur. This is because the reinforcing fibers are arranged in the longitudinal direction of the stem, and therefore are weak against forces in the direction of peeling between the reinforcing fibers. Therefore, by changing the arrangement direction of the reinforcing fibers, the above-mentioned cracks can be avoided to some extent, but it is very time-consuming to manufacture.
It is difficult to obtain perfect quality products.

[Problem that the invention attempts to solve]

In view of the above-mentioned problems, the purpose of the present invention is to form the stem and the large end from metal, and to integrate them into one piece, in order to compensate for the lack of strength at the large end when the connecting rod is formed from fiber-reinforced composite material. Our objective is to provide connecting rods for internal combustion engines that are combined with improved durability and reliability.

[Means to solve the problem]

In order to achieve the above object, the structure of the present invention gradually enlarges the cross section of the large end side of the stem made of fiber reinforced composite material, and the end surface of the large end side of the stem has a semicircular crank pin hole in the lower end surface. , superimposed on the upper end surface of a metal block with bolt insertion holes on both shoulders, an opening with an opening area on the upper end side gradually decreasing in the upper end wall, and a metal block with arms protruding diagonally downward on both side walls. The large end of the stem is fitted into the frame, the arms of the metal frame are overlapped with the shoulders of the metal block, and they are connected together with the metal bearing cap using bolts and nuts.

[Effect]

The large end of the stem, which is made of fiber reinforced composite material, is gradually expanded in width and is butted against a metal block that has a semicircular crank pin hole that is supported by the crank pin. The fitted metal frame is placed over the shoulder of the metal block and bolted together with the bearing cap.

There is no problem because the stem is only repeatedly subjected to tensile and compressive loads mainly in the longitudinal direction as the piston reciprocates, and the longitudinal and lateral loads that the big end receives as the crankshaft rotates are handled by the metal block. Since it is supported by , cracking of the shoulder can be avoided.

[Example of idea]

As shown in FIG. 1, the stem 4 is integrally molded from a fiber-reinforced composite material made of epoxy resin, imide resin, or the like reinforced with reinforcing fibers such as glass, carbon, silicon carbide, or the like. The small end of the stem 4 is provided with a pin hole 12, into which a bush 3 into which a piston pin is fitted is attached. The width of the large end side of the stem 4 is gradually expanded, and the lower end surface 4a is formed by a metal block 6 such as aluminum that constitutes the large end.
is butted against the upper end surface 6b of.

The metal block 6 has shoulders 6a on the left and right,
A semicircular pin hole 13 into which a crank pin is fitted is formed on the lower end surface. The tapered large end of the stem 4 is fitted onto a metal frame 5 having a tapered opening 10 whose opening area gradually decreases toward the upper end, and is bonded with an adhesive. As shown in Figure 2,
Arms 5a project diagonally downward from both side walls of the metal frame 5
is provided with a bolt insertion hole 14.

The metal frame 5 connects the arm 5a to the shoulder 6a of the metal block 6.
A metal bearing cap 7 made of aluminum or the like having a semicircular pin hole 13a is placed on the lower end surface of the metal block 6, and a nut 9 is screwed onto a bolt 8 passing through these.

The stem 4 is in the shape of a thick plate, and the metal frame 5 is provided with a tapered opening 10 having a rectangular cross section in its upper end wall.

As described above, in the present invention, the stem 4, which greatly affects the amount of reciprocating inertia, is integrally molded from fiber-reinforced composite material, the metal frame 5 is fitted around the tapered large end of the stem 4, and the stem 4 is made of epoxy resin. The metal frame 5, the metal block 6 that narrows the crank pin, and the metal bearing cap 7 are bonded together with an adhesive or the like, and are connected with a pair of bolts 8 and nuts 9, so the lower end surface 4a of the stem 4 is strongly pressed against the upper end surface 6b of the metal block 6 by tightening the bolt 8, and at the same time, the large end side of the stem 4 is strongly fitted into the opening 10 of the metal frame 5, resulting in a strong integral connection.

Compared to a conventional connecting rod made entirely of fiber-reinforced composite material, the connecting rod of the present invention weighs 20% less.
% heavier, but since the center of gravity of the connecting rod moves to the large end, the reciprocating inertia weight of the connecting rod is almost the same as the conventional one.

Since the large end of the stem 4 supported by the crank pin is composed of a metal block 6, it is prevented from cracking due to complex loads (especially lateral loads) acting on the bolted joint with the bearing cap 7. The result is a connecting rod for internal combustion engines that is lightweight, reliable, and durable.

[Effect of idea]

According to the present invention, the stem except the large end of the connecting rod is molded from a fiber-reinforced composite material, so the stem has a simple shape, is very easy to mold, and is lightweight.

Since a metal frame is fitted onto the large end of the stem and bonded with adhesive, the stem and metal block can be connected together by fastening the metal frame with a pair of bolts together with the metal block that narrows the crank pin and the bearing cap. are integrally connected by a metal frame, making assembly very easy and improving the strength around the bolt insertion hole and crank pin.

[Brief explanation of drawings]

FIG. 1 is a front view of a connecting rod for an internal combustion engine according to the present invention, FIG. 2 is a plan view of a metal frame of the connecting rod, and FIG. 3 is a perspective view showing the drawbacks of a conventional connecting rod for an internal combustion engine. 4...Stem, 5...Metal frame, 5a...Arm, 6
...Metal block, 7...Bearing cap, 10...
...Opening, 13...Pin hole.

Claims (1)

[Scope of utility model registration request] The cross section of the large end side of the stem is made of fiber-reinforced composite material, and the cross section of the large end side of the stem is made of metal with semicircular crank pin holes on the lower end surface and bolt insertion holes on both shoulders. The large end side of the stem is fitted into a metal frame which is superimposed on the upper end surface of the block, has an opening in the upper end wall with an opening area gradually decreasing on the upper end side, and has arms projecting diagonally downward on both side walls. A connecting rod for an internal combustion engine, characterized in that the arm of the frame is overlapped with the shoulder of a metal block and connected with a metal bearing cap by bolts and nuts.