JPS6242082Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a camshaft for opening and closing a valve in an internal combustion engine, and in particular to a composite camshaft in which different materials such as sintered alloy and steel are combined.

2. Description of the Related Art In recent years, in internal combustion engines, there has been an increasing demand for lighter engines due to the need for fuel efficiency, and attention has been focused on reducing the weight of the camshaft, which is a major part of the engine and is also heavy. This camshaft makes sliding contact with a cam follower such as a rocker arm or tappet, which is an intermediate medium for opening and closing the valve, under high surface pressure, and the way the sliding contact is made is not uniform, so special wear resistance must be taken into consideration for the camshaft and cam follower. .
At the same time, the surface pressure from the cam follower that is applied to the camshaft is high, and the camshaft is also subjected to the load of multiple intake and exhaust cylinders, so the camshaft itself not only requires considerable rigidity, but also increases the engine speed. It is also necessary to improve the fatigue strength of camshafts in response to

As described above, in order to achieve the wear resistance, strength, and weight reduction required for a camshaft, it is necessary to construct a composite camshaft made of appropriate materials.

Conventionally, there are two types of general composite camshafts: those using light alloys and those using steel pipes, but steel pipes are usually used in all but small camshafts.

In addition, a sintered alloy with excellent wear resistance is used for the cam lobe that makes sliding contact with the cam follower. In other words, the composite camshaft takes advantage of the strong and lightweight steel pipe and the sintered alloy that has excellent wear resistance, but the problem is that the sintered alloy that forms the cam lobe and the stem This is a method for joining steel pipes.

Conventionally, methods have been used to braze the cam lobe and the stem, or to fix the cam lobe and the stem by shrinkage of the sintered metal and diffusion bonding during sintering of the cam lobe. However, when brazing the cam lobes and stem or using sintering shrinkage, it is necessary to position and assemble all the cam lobes on the camshaft, which creates an unstable state before joining. In addition to requiring special care when handling camshafts, since brazing and sintering are usually performed in a furnace, the camshaft occupies a large volume compared to the limited furnace volume.
There is a drawback that mass productivity is reduced.

In order to solve the above problems, the present invention has developed a camshaft using a cam pipe in which a cam lobe is fixed to a steel pipe in advance, and a component other than a sintered alloy that is fitted and fixed to the end of the cam pipe. This structure achieves weight reduction, strength, and wear resistance, and furthermore, by providing a protrusion or a fitting groove on the end of the component that fits with the inner or outer circumferential side of the cam pipe. The object of the present invention is to provide a camshaft that is easy to assemble and has high productivity.

Hereinafter, embodiments embodying the present invention will be described based on the drawings. FIG. 1 shows an embodiment of the camshaft of the present invention, in which at least cam pipes 1, 1, 1, 1, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 3, 3, 3, 3, 3 and 4 illustrative embodiments of the camshafts of the present invention are shown.
is formed in advance. This cam pipe is a fraction of the length of the camshaft. The cam lobes 31 and 32 fixed to the cam pipe 1 are usually two cam lobes 31 on the intake side and cam lobes 32 on the exhaust side. The cam pipe 1 is formed by positioning and assembling the cam pipe 2 and sintering it in a furnace. At this time, the sintering of the cam lobes 31, 32 progresses, and at the same time, the metallurgical bonding by diffusion to the steel pipe progresses, and the cam lobes 31, 32 and the steel pipe are firmly bonded.

The cam pipe 1 formed in advance in this way is connected to the journal 4, the journal part 5, the shaft end part 6, and the shaft end journal 7, but the constituent members other than these cam lobes are made of steel, and each A protrusion or a fitting groove is provided on the inner circumferential side of the cam pipe 1 or to fit with the outer circumferential side 11. This is the shaft end part 6 and the shaft end journal 7.
This is because it is located in the middle of the camshaft excluding the camshaft and acts as a joint, and the projections 41 and 41 of the journal 4 or the projection 5 of the journal part 5
1 and 51 are the inner peripheral side 12 of the cam pipe 1, respectively.
It is assembled by mating with the These protrusions 41, 41 and 51, 51 serve as joints with the cam pipe 1 and at the same time serve to reinforce the joint.

Here, the journal part 5 refers to a part that forms gears and cam gears that are camshaft components other than the journal and cam lobe, and as shown in the embodiment, a part 54 forming the journal and a part 53 forming the cam gear. There is no problem even if they are formed integrally with each other, or they may be formed from separate materials and then combined. Furthermore, fitting grooves 61 and 71 are formed in the shaft end component 6 and the shaft end journal 7 for fitting with each cam pipe 1.

After assembling the cam pipes 1, 1, 1, shaft end journal 7, journal 4, journal parts 5, and shaft end parts 6 in this way, the cam pipe 1,
1, a joint portion 14 between 1 and each journal 4, shaft end journal 7, journal component 5, and shaft end component 6;
14, 15, 15, 16, and 17 are fillet welded to complete the connection of the camshaft.

This welding uses MIG, a welding method that uses high-density energy to minimize welding distortion.
TIG welding is preferred, but in cases where the camshaft is complex and the distance between the cam lobe and journal is short, TIG welding with a small amount of wall thickness is preferred.

FIG. 2 shows another embodiment of the camshaft of the present invention. Components interposed between the cam pipes 1 and 1 such as the journal 4 and the cam pipe 1
TIG welding is suitable for welding the
Further, high energy beam welding such as electron beam or laser beam welding is preferable in order to reduce welding distortion and shorten welding time. In this case, as shown in FIG. 2, it is necessary to provide the protruding portion 41 of the journal 4 with a step 42 having the same diameter as the outer peripheral side 11 of the cam pipe 1, and to move the welded portion 43 away from the side surface of the journal 4. .

FIG. 3 shows yet another embodiment of the camshaft of the present invention. When assembling the cam pipe 1 and the journal, as shown in FIG. By performing rotational positioning and temporary fixing, work efficiency can be improved.

FIG. 4 shows yet another embodiment of the camshaft of the present invention. A fitting groove 44 that fits into the outer periphery 11 of the cam pipe 1 is provided in a structural member such as the journal 4 that is interposed between the cam pipes 1 .
Furthermore, in this case, in order to position the journal 4, a fitting groove end portion 45 that comes into contact with the end surface of the cam pipe 1 is required, but this requires a stop ring 46 on the inner peripheral side of the journal 4 as shown in FIG. It can also be substituted by assembling.

However, components such as the journal 4 and journal parts 5 that are assembled between the cam pipes 1 and 1 with grooves that fit on the outer circumferential side of the cam pipes are relatively inferior in terms of strength. ,
Used in internal combustion engines with relatively light loads.

In the embodiments described above, only the cam lobe is made of a sintered alloy, and all other structural members are made of steel; however, depending on the case, the cam gear may be made of a sintered alloy. In this way, if there are sintered metal parts in addition to the cam lobe, the cam lobe and the adjacent sintered metal parts are fixed to a steel pipe in advance to form a cam pipe, and the sintered metal parts interposed between the cam pipes are fixed in advance. It is connected to components other than metal.

As mentioned above, the cam pipe used in the present invention is short, a fraction of the total length of the camshaft, and each cam pipe is formed by fixing only the adjacent cam lobes, and the shape can be unified, making it easy to mass-produce when sintering in a furnace. Moreover, since it is only necessary to pay attention to the positioning of a small number of cam lobes instead of assembling a large number of cam lobes, work efficiency and assembly errors are improved. Similar improvements in mass production and productivity can be achieved when brazing cam lobes to steel pipes.

Further, by providing a protrusion on the journal or journal parts interposed between the cam pipes, not only does the assembly of the cam pipes and the journal parts become easier, but also the bonding strength is increased.

Furthermore, when welding, high-energy beam welding such as MIG, TIG welding, and electron beam/laser welding is possible, resulting in various effects such as less welding distortion and shortening welding time.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the camshaft of the present invention, FIG. 2 is a sectional view of essential parts of another embodiment of the camshaft of the present invention, and FIG. 3 is a sectional view of the camshaft of the present invention. FIG. 4 is a cross-sectional view of a main part showing still another embodiment of the camshaft of the present invention, and FIG. 5 is a cross-sectional view of a main part showing still another embodiment of the camshaft of the present invention. FIG. FIG. 3 is a cross-sectional view of a main part showing a modification example of FIG. In the figure, 1... cam pipe, 2... steel pipe,
3, 31, 32... cam lobe, 4... journal, 5... journal part, 6... shaft end part, 7...
...Shaft end journal, 9...Taper key, 10,4
0... Hole, 11... Outer circumference side, 12... Inner circumference side, 1
4, 15, 16, 17... joining part, 41, 51
...Protruding part, 42...Step part, 43...Welding part, 4
4...fitting groove, 46...stopper ring.

Claims (1)

[Scope of utility model registration request] It consists of a cam pipe in which a cam lobe made of a sintered metal is fixed to a steel pipe in advance, and a component other than a sintered metal that is fitted and fixed to the end of the cam pipe. A camshaft characterized in that it is provided with a protrusion or a fitting groove that fits into the inner circumferential side or outer circumferential side of the cam pipe.