JPH022499Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a camshaft in which a plurality of divided camshaft members are connected to functional members such as cams and journals at the respective shaft ends.

Conventionally, camshafts have been integrally formed by casting, but especially large camshafts have a long overall length and a large number of cam parts and journal parts, so naturally the mold is large. Therefore, a large mold is required, but if it is difficult to make a large mold,
It is not possible to manufacture large long shaft camshafts.
Even if it were possible to create a mold for a large camshaft, the straightness yield of the camshaft would be similarly poor due to the long shaft casting, resulting in high costs.

On the other hand, it has been proposed to divide the camshaft member into a plurality of parts and join the divided camshaft members to a functional member at each shaft end to increase the size of the camshaft. To join the split camshaft member to the functional member at each shaft end, welding,
Brazing, soldering, bonding with various adhesives, fixing with screws, etc. are widely used. However, welding requires high thermal energy, which tends to cause local material deterioration and poor dimensional accuracy due to thermal distortion, requires large and expensive equipment, and requires skill.

Further, brazing, soldering, and joining using various adhesives are not so difficult compared to welding. However, these means usually require the interposition of a fusible substance in addition to the two members to be joined, which requires careful handling and is time-consuming. Moreover, even though great progress has been made in recent years, we still cannot expect much reliability in terms of the strength of the joint or the uniformity of the material on the joint surface, and in the case of adhesives, there is a risk of material deterioration over time. However, there remains a problem. Further, fixing with screws not only increases processing cost but also makes positioning in the circumferential direction difficult.

On the other hand, as joining means that do not use welding or a third material, there are conventionally employed shrink fitting and elastic fitting. Although these physical and mechanical means are excellent in that they take advantage of the physical properties of materials, they are not perfect in that they do not essentially include the metallurgical meaning of fusing and joining objects together. It somewhat lacks the meaning of joining.

As mentioned above, in welding, equipment costs are high, productivity and workability are poor, and objects with different properties from the main body cannot be joined together.

On the other hand, in brazing and soldering, it can only be used for small items that do not pose a problem in terms of strength.
Furthermore, in bonding using various adhesives, there are concerns about their heat resistance, changes in substances over time, and the like. Furthermore, fixing with screws not only increases processing costs but also makes positioning in the circumferential direction difficult. Therefore, in terms of mass-producing industrial parts, mechanical joining means presently have no problems and can be said to be the most superior method.

However, it goes without saying that it is more desirable from the viewpoint of strength to integrate the shaft end portions of each of the plurality of split camshaft members and the functional member in such a manner that they are completely fused at the joining interface.

In view of this, the present invention has been developed to overcome the shortcomings of the various conventional joining methods by providing a powerful means that not only achieves mechanical fitting but also metallurgical integration. By joining the shaft end of each of the plurality of split camshaft members and the functional member using The purpose is to provide a camshaft.

To achieve the above object, the present invention provides a camshaft in which a plurality of divided camshaft members are connected to a functional member such as a cam, a journal, etc. at each shaft end, and the functional member is interposed at the joint. A side surface of the functional member has a flange protruding in the axial direction, and the shaft end of the split camshaft member has a fitting hole into which the flange is fitted and whose inner circumferential diameter is slightly smaller than the outer circumferential diameter of the flange. have,
This is characterized in that the inner periphery of the fitting hole is cut (shaving) by the outer periphery of the flange, or conversely, the outer periphery of the flange is cut (shaving) by the inner periphery of the fitting hole, and the fittings are then fitted together.

Hereinafter, embodiments embodying the present invention will be described based on the drawings.

Figures 1a and 1b show an embodiment of the camshaft of the present invention in which a plurality of split camshaft members are joined to a functional member at each shaft end.
Figure 1a shows the state before the both ends of the functional member 1 such as a cam or journal are joined to the shaft end of the split camshaft 3, and Figure 1b shows the state after they have been joined.

In FIG. 1a, a functional member 1 such as a cam or journal has a flange 2 projecting in the axial direction on the side surface thereof. The functional member 1 is made of ceramics, plastics, alloy steel, etc., and can be obtained by forging, casting, sintering, or other means. At the shaft end of the split camshaft member, that is, the hollow stem 3, there is a fitting hole 3' into which the flange 2 is fitted and whose inner diameter is slightly smaller than the diameter of the outer circumference 2' of the flange 2.

Since the stem 3 is hollow, the weight of the entire camshaft can be reduced.

Next, to explain the joining of the functional member and the stem, first, as shown in FIG. The stem 3 is press-fitted toward the flange 2 of the functional member 1 while lightly cutting (shaving) the circumference. In most cases, the shavings adhere to the inner periphery of the fitting hole 3' of the stem 3 and form a raised part 4. At the same time, a stepped part 5 is formed on the peripheral wall of the flange 2 during cutting, so that the axis of the stem 3 The joint area between the end portion and the flange 2 of the functional member 1 increases, contributing to an improvement in joint strength. In this way, a large camshaft can be obtained by sequentially arranging and joining the stem and the functional member.

2a and 2b show another embodiment of the camshaft of the present invention. There is no difference from the embodiment shown in FIGS. 1a and 1b except that the stem 3 is solid, and the same function can be achieved.

3a and 3b show still another embodiment of the camshaft of the present invention.

In this embodiment, as shown in FIG. 3b,
In order to improve the fusion of the joint, while heating the shaft end of the functional member 1, the outer periphery 2' of the flange 2 of the functional member 1 is lightly cut (shaving process), and the stem 3 is pressed and fitted toward the flange 2. Match. In most cases, the shavings adhere to the outer periphery 2' of the flange 2 and form a raised part 4, and at the same time, during cutting, a stepped part 5 is formed on the peripheral wall of the shaft end of the stem 3, so The joint area between the flange 2 and the functional member 1 increases, contributing to an improvement in joint strength.

4a and 4b show still another embodiment of the camshaft of the present invention. There is no difference from the embodiment shown in FIGS. 3a and 3b except that the stem 3 is solid, and the same function can be achieved.

In either embodiment, the respective functional members 1 are sequentially arranged along the rotation axis of the stem 3 at a predetermined angle perpendicular to the rotation axis of the stem 3, and the joints are joined by cutting (shaving processing). Therefore, the assembly work is easy, and large camshafts can be produced in large quantities at low cost.

Note that the material and type of the functional member 1 are not limited to those described above, and the material and type of the stem 3 are also not limited in any way, so various combinations of materials and types are possible. Further, although the present invention relates to a camshaft, it goes without saying that shafts such as crankshafts and other mechanical structural parts can also be manufactured by the same method.

As described above, the present invention has a flange 2 protruding in the axial direction on the side surface of the functional member 1, and the flange 2 is fitted into the shaft end of the split camshaft, that is, the stem 3. It has a fitting hole 3' whose inner circumference diameter is slightly smaller than the outer circumference 2' diameter, and the inner circumference of the fitting hole 3' is connected to the outer circumference 2' of the flange 2, or vice versa. Since the inner periphery of the fitting hole 3' is cut (shaving) and fitted and joined, the functional member 1 can be firmly attached to the stem 3 without causing local material deterioration of the joint part or material deterioration over time. This can significantly improve camshaft life. That is, since cutting (shaving) is simultaneously bonding, the new surfaces created by cutting come into contact with each other, resulting in a large contact area. Since the raised portion 4 and stepped portion 5 of the shavings further increase the contact area, the bonding strength can be improved.

Further, since the camshaft member is small in size, it can be mass-produced extremely easily by forging, punching, etc., and the functional members 1 can be arranged along the rotation axis of the stem 3 at a predetermined angle perpendicular to the rotation axis of the stem 3. However, since the joining portions are simply joined by cutting (shaving processing), assembly work is easy, and large camshafts can be produced in large quantities at low cost.

[Brief explanation of the drawing]

FIGS. 1a and 1b are partial cross-sectional views schematically showing a state in which an embodiment of the camshaft of the present invention is joined, and FIG. Partial sectional view of state, Figure 1b
2 is a partial sectional view showing a state in which both flanges of the functional member and the stem are joined; FIGS. 2a and 2b are partial sectional views schematically showing a state in which another embodiment of the camshaft of the present invention is joined; 3A and 3B are partial sectional views schematically showing a state in which still another embodiment of the camshaft of the present invention is joined, and FIGS. 4A and 4B are partial sectional views showing still another embodiment of the camshaft of the present invention being joined. FIG. 3 is a partial cross-sectional view schematically showing the state. In the figure, 1... functional member, 2... flange, 2'... outer periphery of flange 2, 3... split camshaft member, i.e. stem, 3'... fitting hole of stem 3, 4... raised portion , 5... is a stepped portion.

Claims (1)

[Scope of utility model registration request] In order to connect multiple split camshaft members to functional members such as cams and journals at each shaft end,
In the camshaft in which the functional member is interposed at the joint part, the functional member has a flange protruding in the axial direction on the side surface thereof, the flange is fitted into the shaft end of the split camshaft member, and the flange outer circumferential diameter is It has a fitting hole whose inner diameter is slightly smaller than that of the fitting hole, and the inner periphery of the fitting hole is cut by the outer periphery of the flange, or conversely, the outer periphery of the flange is cut by the inner periphery of the fitting hole. A camshaft characterized by: