JPH0519521Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a valve lifter forming a part of a valve operating mechanism of an internal combustion engine, and particularly relates to a valve lifter that has been subjected to wear-resistant treatment.

[Conventional technology]

In a valve operating mechanism in which a camshaft is disposed directly above the shaft of an intake/exhaust valve, a cup-shaped valve lifter is interposed between the shaft end of the intake/exhaust valve and the cam of the camshaft. For example, as shown in Utility Model Application No. 58-165508, this valve lifter is fitted into a guide lifter hole so as to cover the shaft end of the intake and exhaust valve, and when the cam rotates, The valve lifter slides back and forth while being displaced according to the amount of lift obtained from the cam profile. At this time, considering that local forces act on the valve lifter from the shaft ends of the intake and exhaust valves, the parts of the valve lifter where the shaft ends of the intake and exhaust valves come into contact are made of hard material such as metal carbide or ceramic. A chip has been cast into it.

[The problem that the idea aims to solve]

However, when the above-mentioned chips are cast, there is a concern that the increase in weight increases, which may impair the followability of the intake and exhaust valves at high speeds. It is difficult to make a large boundary surface for the chip that is cast into the valve lifter, and there is a difference in thermal expansion between the valve lifter and the chip, so there is a problem that sufficient bonding strength cannot be achieved.

Therefore, the technical problem of the present invention is to improve the wear resistance of the valve lifter by increasing the bonding strength of the chips without increasing the weight.

[Means to solve the problem]

The means taken in the present invention to solve the above technical problem is that in a valve lifter that slides back and forth according to the rotation of a cam while abutting against the end face of the shaft of an intake and exhaust valve, , is characterized by a spirally-wound wire mesh chip cast into it.

[Effect]

According to this method, the valve lifter material penetrates into the chip through the wire mesh and is firmly bonded to the chip.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[First Embodiment] FIG. 1 shows a valve train in which a camshaft 6 is disposed directly above an intake and exhaust valve 2 of an internal combustion engine. Here, a valve spring 3 is installed around the shaft 2a of the intake/exhaust valve 2, and a disk-shaped retainer 5 is attached to the end of the shaft 2a with a cotter 4 in the center. There is. thus,
When the end surface of the valve spring 3 hits the retainer 5, the intake and exhaust valves 2 receive a spring force in the direction of closing.

Between the camshaft 6 and the intake and exhaust valves 2,
A cup-shaped valve lifter 7 made of aluminum alloy is interposed. The valve lifter 7 is slidably fitted into a guide lifter hole 8 so as to cover the shaft end of the intake/exhaust valve 2 and partially cover the outside of the valve spring 3. Note that the top 7a of the valve lifter 7 is connected to the cam 6a of the camshaft 6 when the intake and exhaust valves 2 are closed.
A shim 9 is installed to adjust the gap between the two. In an internal combustion engine, this gap is provided to release thermal expansion of the valve train.

Top 7a of valve lifter 7 with shim 9 installed
In this case, the portion of the intake and exhaust valve 2 that the shaft 2a comes into contact with is subjected to wear-resistant treatment. Specifically, as shown in FIG. 2, chips 10 are cast in which wire mesh is spirally wound so as not to touch each other and cut into rings of a predetermined length as shown in FIG. As a result, wire mesh wires 10a are scattered on the contact surface of the top portion 7a, mixed with the aluminum alloy, as shown in FIG. Here, metal wires such as carbon steel are used as wire rods for the wire mesh, and metal wires subjected to diffusion and penetration treatment with carbon, nitrogen, etc., and surface hardening treatment such as wear-resistant plating are used.

As described above, the wear resistance of the abutment surface of the top portion 7a is improved by forming a metal-reinforced composite portion by casting the chip 10 made of a spirally wound wire mesh. In addition, since the chip 10 is formed of a wire material such as a wire mesh, there is not a significant increase in weight, and the flowability during aluminum alloy casting is improved. The alloy has penetrated and the bond strength of the chip 10 has increased. Therefore, the bonded portion is less likely to separate due to the difference in thermal expansion between the wire rod of the chip 10 and the aluminum alloy. In particular, since the tip 10 is formed by spirally winding a wire mesh, by selecting the number of windings in advance in addition to the wire diameter and mesh size, the tip 10 can be This makes it easy to adjust the proportion of wire rods included, that is, the composite volume proportion of the abutting surface of the top portion 7a.

[Second Example] The second example shows a modification of the method for forming the chip 10 of the first example, and as shown in FIGS. 5 and 6, the wire mesh sheet 1 forming the chip 10 is
A resin tape 20 is provided along one surface of 0b. When the wire mesh sheets 10b are piled up and wound in a spiral shape, when the resin tape 20 is rolled up as shown in FIG.
Since the gap is created according to the thickness of the wire mesh, it is easy to maintain the spiral gap between the inner and outer wire mesh while inserting the chip 1.
0 can be formed. The resin tape 20 is eluted when the chip is cast, and the aluminum alloy that is the valve lifter material enters instead.
It has become possible to obtain a uniform composite part in which the parts do not come into contact with each other. Other compositions/effects/
The effect is the same as in the first embodiment.

[Third Embodiment] The third embodiment shows a case where the material of the valve lifter 7 is fiber-reinforced plastic, and as shown in FIG.
A cylindrical chip 30 is used, in which a spirally wound wire mesh 31 is impregnated in advance and heated and hardened. This chip 30 is then cast together with fiber-reinforced plastic. Therefore, there is almost no difference in thermal expansion between the chip 30 and the valve lifter 7,
The chip 30 will not separate from the valve lifter 7 due to this difference in thermal expansion. When a foreign material is cast into fiber-reinforced plastic, if the fiber density in the area where the foreign material is cast becomes smaller, the strength will partially decrease. This sufficiently compensates for the decrease in strength when the chip 30 is cast.

[Effect of idea]

As described above, according to the measures taken by the present invention, the valve lifter material is penetrated into the chip through the mesh of wire gauze, so that it is possible to improve the abrasion resistance while suppressing the weight increase and making it possible to connect the chip and valve lifter material. It is possible to increase the bonding strength with

Furthermore, since the tip is spirally wound with wire mesh, the wear resistance of the intake/exhaust valve contact portion can be freely changed by selecting the wire diameter, mesh size, and number of turns.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a valve train including a valve lifter according to a first embodiment of the present invention, and FIG.
Figure 3 shows a wire mesh wound spirally with chip material cast into the valve lifter shown in Figure 3. Figure 3 shows a chip formed by cutting the spirally wound wire mesh into rings. Figure 4 shows a chip formed by cutting the spirally wound wire mesh into rings. , FIG. 5 is a view showing the contact surface of the top of the valve lifter in FIG. Figure 5 shows the state in which the wire mesh sheet is spirally wound, and Figure 7 shows a chip formed into a cylindrical body by impregnating the spirally wound wire mesh with resin in the third embodiment of the present invention. FIG. 2... Intake and exhaust valve, 2a... Shaft, 6a... Cam, 7... Valve lifter, 10... Chip.

Claims (1)

[Scope of utility model registration request] A valve lifter that slides back and forth as a cam rotates while abutting against the end face of an intake/exhaust valve shaft, characterized in that a tip of a spirally wound wire mesh is cast in the place where the end face of the shaft abuts. Valve lifter.