JPS6375303A - Combination valve lifter - Google Patents

Abstract

PURPOSE:To improve anti-wear and anti-pitching qualities by join-fixing a lid-portion-disk formed of high strength steel material or sintered body to a trunk portion formed of ferrous material or aluminum alloy. CONSTITUTION:The trunk portion 1 of the outer perimeter portion of a valve lifter is formed of ferrous material or aluminum alloy. A lid-portion-disk 2 is formed of high strength steel material, such as SKD 11 or sintered material. The projecting portion 4 of the lid-portion-disk 2 is press-put onto the inner perimeter surface 3 of the trunk portion 1. A join-fixing is completed by irradiating laser beams to a boundary portion. By this, anti-wear and anti-pitching qualities may be heightened.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a combination valve lifter for a valve drive device of an internal combustion engine, and more specifically, the cover disk on the sliding surface with the cam is made of high-strength iJ material or sintered material. The present invention relates to a combination valve lifter which is formed, fitted into a body, and fixed by laser welding to improve durability.

BACKGROUND OF THE INVENTION In recent years, internal combustion engines have become smaller, have higher output, and higher performance, and increasingly severe conditions are being imposed on their functional parts, and there is a strong demand for extending the life of internal combustion engines. Valve lifters are also exposed to harsh environments such as high-speed rotation more than ever before, and there is a strong demand for their wear resistance and pitting resistance.

As shown in the operational diagram in Figure 4, the valve lifter directly slides on the cam 8 that rotates at high speed, so it requires high wear resistance and pitting resistance, as well as strength at high temperatures since it is used in a high temperature environment. be done. Currently the valve lifter is SCM415
．． 420 or 5Cr415.420 is used, but in more severe environments such as small, high-speed valve lifters for motorcycles in recent years, cracks and wear due to fatigue occur on the sliding surface with the cam, resulting in insufficient It is becoming difficult to adapt.

As a countermeasure, 5KDII, a cold die steel with excellent wear resistance and pitting resistance, has recently been adopted.

Some valve lifters have been cut out from 5KDII and put into practical use, but 5KDII is much more expensive than SCM or 5Cr415.420, and has extremely poor workability. Cold forging is also difficult because it is thin, and requires a machining allowance of about 2 mm, which reduces the effect of cold forging and causes problems such as the inability to use cold forging.

In addition, as shown in Fig. 5, the main body 11 of the valve lifter is made of 5IOC1 or 5Cr415 material, which is inexpensive and has good workability, and the portion of the cover disk 12 that directly slides on the cam is made to have wear resistance and pitting resistance. The main body 11 is made of a superior sintered body.
bonded by liquid phase sintering.

Although a combination valve lifter has been provided and put into practical use, there are problems such as deformation or material deterioration because the valve is passed through a high-temperature furnace of 1100° C. or higher during liquid phase sintering.

Means for Solving the Problems The present invention has been made by focusing on such conventional problems, and the outer peripheral portion that does not directly slide on the cam is made of carbon steel pipe or aluminum, which is inexpensive and has good workability. A lid disk that slides directly on the cam is formed on a body made of an alloy or formed by cold forging, and made of cold die steel or a sintered body of high-strength steel with excellent wear resistance and pitting resistance, The purpose of the present invention is to provide an inexpensive valve lifter that is fitted into the body and fixed by laser welding, thereby exhibiting excellent wear resistance and pitting resistance.

Furthermore, when an aluminum alloy is used for the body, the weight of the valve lifter can be reduced and excellent effects can be achieved in response to high-speed rotation.

Laser welding uses a high-power C02 laser, which has been used in a variety of industrial applications in recent years.As is well known, laser beams have good beam convergence and extremely high energy density, so they can be heated in a short time. That's enough. Because it is heated locally, there is almost no thermal effect on the surrounding area, and there is little thermal deformation, so most of the body and lid disk are not heated and are maintained at a low temperature, so there is no possibility of material deterioration or distortion due to high temperatures. can avoid. Furthermore, it has excellent features such as welding conditions can be freely obtained and can be easily adjusted. Moreover, it has excellent economical features such as high productivity and low cost.

When fitting and assembling the lid disc into the body, the lid disc is firmly held in the body by press-fitting, making welding work easier and complete, and the welding finish is better. .

In addition, valve lifters are subjected to surface treatment such as carburizing or nitriding to add wear resistance. However, surface treatment may be applied after the body and lid disc are joined together, or the body and lid disc may be surface treated before joining. It is also possible to surface-treat the disks separately and then join them together.

Example Hereinafter, the present invention will be described in detail with reference to examples.

Embodiment (1) As shown in FIG. 1, the body 1 at the outer periphery of the valve lifter is formed by cold forging using carbon steel, and the inner periphery on which the lid disk 2 is press-fitted is formed on the upper inner periphery. Surface 3 is formed by processing.

The lid disk 2 is made of 5KDII, and has a convex portion 4 press-fitted into the inner circumferential surface 3 of the body.

The convex portion 4 of the lid disk 2 is press-fitted into the inner circumferential surface 3 of the body 1, and the assembled valve lifter is held in a jig attached to a one-turn head, and while rotating the valve lifter, the body and the lid disk are rotated. Welding was carried out under the following welding conditions using a laser beam 7 provided on the boundary of the welding gas and using argon gas as a shielding gas.

Laser welding conditions Laser device 3kwCO, laser device Laser output 1kw Welding speed 3 sec/rpm (3cm/5e
e) As a result of checking the state of the joint of the valve lifter after joining by breaking it, as shown in the cross-sectional view of Fig. 3, the welded part 6 of the joint part was formed uniformly without any variation and was completely welded. This was confirmed.

Furthermore, a water pressure test of 7 kg/Cm was conducted on the inner circumference of the valve lifter, but no abnormality such as leakage was observed, and the joint was found to be in good condition.

Example (2) A lid disk 2 made of SKDII is formed into a disk having an outer peripheral surface 5 that is press-fitted into the inner peripheral surface 3 of a body formed by cold forging using carbon steel, and the entire lid disk 2 is formed. The laser beam 7 is applied to the boundary between the body 1 and the lid disc 2 while rotating the combined valve lifter.
It was irradiated and welded.

It was confirmed that the condition of the welded part and the results of the water pressure test were the same as in Example (1), with no problems and the joint was good.

In both Examples (1) and (2), the laser beam 7 was irradiated from the outer peripheral surface, but it is also possible to irradiate from the inner peripheral surface with the laser beam 7', and the results are as good as those from the outer peripheral surface. A bond was obtained.

Further, although the laser beam irradiation was performed while rotating the valve lifter, it is also possible to fix the valve lifter and irradiate the laser beam while rotating, and similarly good bonding can be obtained.

The shape of the joint where the body and the lid disk are assembled is not limited to the one in this embodiment, but can be freely selected as long as it can be fitted into the correct position and come into close contact with each other.

Effects According to the present invention, the lid disk that directly slides on the cam is made of high-strength steel or sintered material with excellent wear resistance and pitting resistance, and the outer peripheral portion of the body that does not slide directly on the cam is inexpensive and easy to process. By combining materials made of high-quality carbon steel or aluminum alloy and joining and fixing them by laser welding, which is economical and ideal for welding valve lifters, it has excellent wear resistance and pitting resistance, and can withstand harsh conditions. The effect of being able to obtain a valve lifter that can meet various conditions at a low cost is remarkable.

[Brief explanation of the drawing]

Fig. 1 A sectional view of the valve lifter of the first embodiment Fig. 2 A sectional view of the valve lifter of the second embodiment Fig. 3 A sectional view of the boundary between the body and the cover disc Fig. 4 An illustration of the operating state of the valve lifter Figure 5 Cross-sectional view of a conventional combination valve lifter 1 = Body 2: Lid disc 6: Welded part 7: Laser beam 7: Laser beam 8: Cam 9: Push rod

Claims (1)

[Claims] In a combination valve lifter in which a cover disk 2 that directly slides on a cam is bonded and fixed to a valve lifter body 1 made of different materials, the body 1 is made of iron-based material or aluminum alloy, and has wear resistance and pitting resistance. 1. A combination valve lifter characterized in that a lid disk 2 formed of a high-strength steel material or a sintered body with excellent properties is inserted and fixed by irradiating a laser beam onto the boundary portion of the combination.