JPS6287603A - Tappet valve mechanism with roller - Google Patents

Abstract

PURPOSE:To reliably fix the pivotal pin of the roller of a valve driving tappet with coller by inserting softening members made of nickel or iron containing low carbon into a junction between the tappet and the pivotal pin and welding them. CONSTITUTION:When a pivotal pin 10 supporting a roller brought into contact with a valve driving cam is to be fixed to the end section of a tappet 5 having a hole for a push rod inside it, first a roller 13 coupled with a needle bearing 14 is inserted into the recess 7 of the tappet 5, and the pivotal pin 10 is inserted into a through hole provided on the tappet. Softening members 12 mainly made of nickel or iron containing 0.2% or less of carbon are inserted into grooves around the pivotal pin 10. Next, they are welded with a laser beam 21 while the whole tappet 5 is rotated around the central axis of the pivotal pin 10. Softening members 12 are melted to soften the carbon content of a joint, and cracks are prevented from occurring on the welded metal.

Description

Detailed Description of the Invention Object of the Invention (Field of Industrial Application) The present invention relates to valve lifters, rocker arms, etc. used for transmitting cam displacement to valves in internal combustion engines for automobiles, ships, etc. The present invention relates to a valve mechanism, and more specifically, to an assembly structure of a valve mechanism in which a roller is added to a contact portion with a cam.

(Prior art) Some valve mechanisms, such as valve lifters and rocker arms, are equipped with a mechanism to reduce friction and wear with the cam nose.
Some have rollers installed in the contact area with the cam. In this valve mechanism, in order to rotatably support the roller on the valve mechanism main body, the support shaft pin of the roller must be joined to the valve mechanism main body.

Welding seems to be suitable as a means of joining, but carbon steel, case-hardened steel, or cast iron with a high carbon content is usually used for the main body of the valve train, and the spindle pin also has a high carbon content. Since bearing steel is used, the influence of carbon is large, and joining by welding is generally considered difficult.

Therefore, conventional valve lifters with rollers have been formed by the following two joining methods.

■ Joining by caulking As shown in FIG.
The fork portion 35 of No. 4 is inserted through the fork portion 35, and the thin wall portions 36 provided at both ends of the support shaft pin 33 are expanded in diameter by caulking and fixed to the lifter body 34.

■ Connection by screwing As shown in Fig. 6, the fork portion 3 of the lifter main body 34
5 and the support shaft pin 33, and a male screw 38 is screwed into the female screw 37 from below the fork part 35, thereby fixing the lifter main body 34 and the support shaft pin 33. It is.

(Problem to be Solved by the Invention) However, in the conventional example (2) above, the shape accuracy (roundness, cylindricity, etc.) of both ends of the spindle pin 33 is easily damaged by caulking, and the spindle pin 33 and needle Friction and wear between the bearings 31 and between the needle bearings 31 and the rollers 32 may increase.

In addition, in the conventional example (2) above, the female thread 37 is processed and the male thread 38 is processed.
This not only increases the number of steps and costs, but also
There is a problem in that the fork portion 35 of the lifter main body 34 becomes thick, and measures against loosening of the male screw 38 are required.

The purpose of the present invention is to solve these problems, and to provide a roller-equipped valve in which the main body of the valve train mechanism and the roller support pin can be easily and reliably joined by welding, and the welded part has high toughness and does not cause cracks. The goal is to provide a mechanism.

Structure of the Invention (Means for Solving the Problems) The present invention provides a method in which the main material of the joint between the valve mechanism main body and the roller support pin is nickel or iron with a carbon content of 0.2% by weight or less. A valve mechanism with rollers is provided in which a relaxation member is inserted and the joint portion is welded by melting and solidifying the relaxation member.

(Function) The mitigation member moderates the amount of carbon content in the joint (welded metal) and maintains the toughness of the weld metal, thereby preventing the occurrence of cranks in the weld metal.

(Example) An example in which the present invention is embodied in a valve lifter with a roller for an automobile internal combustion engine having an OHV valve mechanism will be described with reference to FIGS. 1 to 4.

As shown in FIGS. 1 and 2, a cam 2 for opening and closing intake and exhaust valves (not shown) is formed on a camshaft 1 provided inside an internal combustion engine, and a cam 2 is provided above the cam 2.
A valve lifter 4 with a roller is provided to transmit the displacement of the valve to a bushing rod 3 for opening and closing the intake and exhaust valves. Hereinafter, the state of the valve lifter 4 with rollers will be explained in order of the state before assembly, the method of assembly, and the state after assembly.

[Condition before assembly @] The lid body 5, which forms the main part of the valve lifter 4 with rollers, has a high carbon content (0, 2 ffi% or more)
It is formed into a cylindrical shape from carbon steel, case hardened steel, or cast iron. Two fork portions 6 are made of the same material and integrally protrude from the lower part of the lifter main body 5, and a rectangular recess 7 is formed between the two fork portions 6.

Further, pin holes 8 are transparently provided in both fork portions 6, and a cylindrical hole 9 whose diameter increases stepwise is formed at the outer edge of each pin hole 8. The diameter of this cylindrical hole 9 is 0.2 greater than the diameter of the pin hole 8.
It is formed at a depth of ~0.61 MI and around 1 Mi. A spindle pin 10 made of bearing steel with a high carbon content (0.2% or more) is inserted into both pin holes 8, and a cylindrical hole is inserted between the spindle pin 10 and the cylindrical hole 9. A shaped gap 11 is formed.

A ring-shaped relaxation member 12 mainly made of nickel or iron with a carbon content of 0.2ffiff1% or less is inserted into this gap 11. Therefore, specific examples of the material of the relaxation member 12 include pure nickel, nickel-based alloy, pure iron, extremely mild steel, and the like. In addition, the relaxation member 12 has a gap 1
The ring surface thickness is 0.1 to 0.3 m so that it fits exactly into 1.
The ring height is around 1m. Note that the relaxation portion vJ'12 may be a complete ring without any breaks, or may be a ring cut out from a plate and rolled.

Further, a roller 13 that contacts the cam 2 is disposed in the recess 7 of the lifter main body 5, and the roller 13 is rotatably supported by the support pin 1Q via a needle bearing 14. .

A cylindrical recess 15 is formed in the upper part of the lifter main body 5, and the lower end of the bushing rod 3 comes into contact with the bottom surface of the recess 15.

[Assembling method] First, as shown in FIG. 3, place the roller 13 and needle bearing 14 in the recess 7 of the lifter main body 5,
The spindle pin 10 is inserted into the bottle hole 8 and the roller 13. Further, as shown in FIG. 4, a relaxation member 12 is fitted into a gap 11 formed between the support pin 10 and the cylindrical hole 9.

The valve lifter 4 thus assembled is set in a laser welding device or an electron beam welding device.

Then, as shown in FIG. 4, while rotating the valve lifter 4 around the support pin 10, the beam nozzle 21
A laser beam or an electron beam is emitted from the center and irradiated onto the joint between the lifter main body 5 and the spindle pin 10 with the relaxation member 12 as the center. The strength of the beam is such that the relaxation member 12 melts and penetrates into the fork portion 6 and the support shaft pin 10, and the depth of penetration is 1 to 1.5 m. Here, the entire metal to be melted and solidified, including the relaxation member 12, is referred to as the weld metal 2.
2, and the weld metal 22 and the surrounding heat-affected zone are collectively referred to as the weld zone.

As the relaxation member 12 with a carbon content of 0.2% by weight or less melts into the fork portion 6 and the spindle pin 10, which have a high carbon content, the carbon content of the weld metal 22 is reduced. The effect of carbon on welding is alleviated and weldability is improved. Furthermore, the toughness of the weld metal 22 is improved, and cracks can be prevented from forming in the weld metal 22. When the carbon content in the relaxation member 12 is more than 0.2% by weight, the relaxation effect is reduced.

Welding is completed when weld metal 22 solidifies by natural cooling. In particular, a laser beam or an electron beam has an extremely high energy density and is locally concentrated, so the heat affected zone becomes smaller and the toughness of the entire weld zone improves. In addition, the 8-contact is completed without any thermal effect on the contact portion between the spindle pin 10 and the needle bearing 14.

[State after assembly 1 In the valve lifter 4 assembled as described above, the spindle pin 10 is joined to the fork portion 6 by a weld metal 22, as shown in Fig. 1.2. The cylindrical hole 9 of the fork portion 6 and the relaxation member 12 are melted together and deformed. In this way, according to this embodiment, the lifter main body 5 and the support pin 10 can be easily and reliably joined by welding.

Moreover, as mentioned above, the relaxation member 1 with a low carbon content
2 relaxes the carbon content of the weld metal 22,
The toughness of the weld metal 22 can be increased and the occurrence of cracks can also be prevented. In particular, since the relaxation member 12 is formed in a ring shape, the carbon content is relaxed all around the joint, thereby preventing the occurrence of cracks.

If the beam welding is performed without using the relaxation member 12, cracks are likely to occur in the weld metal 22.

Even if there are no cracks immediately after welding, residual stress remains in the welded part, so there is a risk of cracking over time or if repeated external stress is applied. In this embodiment, the effect of the relaxation member 12 makes it possible to eliminate these concerns about crank occurrence.

Furthermore, in this embodiment, the joint portion is locally heated by laser welding or electron beam welding, so that the heat affected zone becomes smaller. Therefore, the toughness of the entire weld including the heat affected zone is also improved.

To explain the operating state of the valve lifter 4 with rollers configured as above, the lower end of the roller 13 protrudes downward from the fork part 6 and contacts the cam 2, and moves up and down while rotating according to the displacement of the cam 2. In order to do this, the entire pulbrator 4 is moved up and down. In this way, since rolling resistance is dominant in the contact between the roller 13 and the cam 13, friction and wear between the two are significantly reduced. As the lid body 5 moves up and down, the push rod 3 in contact with the recess 15 moves up and down, opening and closing intake and exhaust valves (not shown).

It should be noted that the present invention is not limited to the configuration of the above-mentioned embodiments, but can be modified and embodied as desired without departing from the spirit of the invention, for example, as described below.

(1) The dimensions and shape of the relaxation member 12 can be changed depending on the dimensions and carbon content of the valve mechanism main body and the support pin.

(2) The present invention can be applied not only to a valve lifter with a roller, but also to various valve mechanisms such as a rocker arm with a roller. For example, in the case of a rocker arm with rollers, the relaxation member can be used at the joint between the rocker arm body and the roller support pin.

Effects of the Invention As detailed above, the present invention has the excellent effect that the valve mechanism main body and the roller support pin can be easily and reliably joined by welding, and that the weld metal has high toughness and does not cause cracks. play.

[Brief explanation of drawings]

Figures 1 to 4 show an embodiment of a valve lifter with a roller that embodies the present invention. Figure 1 is a sectional view of the completed embodiment, Figure 2 is a side view, and Figure 3 is an assembly. 4 is a sectional view showing the welding method, FIG. 5 is a sectional view of a conventional example, and FIG. 6 is a sectional view of another conventional example. 5... Lifter main body, 10... Support pin, 12...
- Relaxation member, 13...roller.

Claims (1)

[Claims] 1. The main material of the joint between the valve mechanism body (5) and the spindle pin (10) of the roller (13) is nickel or iron with a carbon content of 0.2% by weight or less. A valve mechanism with a roller, characterized in that a relaxation member (12) is inserted, and the joint portion is welded by melting and solidifying the relaxation member (12). 2. The joint part is provided with a cylindrical gap (11), and a ring-shaped relaxation member (12) is inserted into the gap (11). Valve mechanism with rollers described.