JPH11270307A - Assembling type camshaft for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the mechanical durability of a slit part while enlarging the pressure receiving area of the slit part by fastening a cylindrical member to an end of a cylindrical shaft member over the diameter thereof with pipe enlarging method, and providing this cylindrical member fastened part with a slit for driving a pump or the like. SOLUTION: Cam lobes 21, 22 and a cylindrical member 31 are fastened to a hollow shaft 1 as a shaft member by the pipe enlarging method, and the cylindrical member 31 and the hollow shaft 1 are formed with a slit 4 by milling the hollow shaft 1 and the cylindrical member 31 after fastening the cylindrical member 31 to the hollow shaft 1. Or, before fastening the cylindrical member 31 to the hollow shaft 1, a slit can be previously formed in the hollow shaft 1 and the cylindrical member 31, and thereafter, the hollow shaft 1 and the cylindrical member 31 are fastened to each other so as to form the slit 4. With this structure, thickness of the slit part can be increased, and an assembling type cam shaft for engine having high mechanical durability can be easily manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembling camshaft for an engine used in a reciprocating internal combustion engine such as an automobile engine, and more particularly to an engine in which a cam lobe is joined to a camshaft having a hollow shaft by using a pipe expansion method. The present invention relates to an assembled camshaft.

[0002]

2. Description of the Related Art Conventionally, as a camshaft used in an automobile engine or the like, there is a cast camshaft manufactured by a casting method as shown in FIG. FIG. 7A is a side view showing the structure of a conventional cast camshaft, and FIG.
(B) is a right side view of the cast camshaft. The cast camshaft is provided with a cam lobe 71 and is provided with a slit 44 forming a narrow groove directly at the end of the shaft 20 by machining using a milling machine or the like. The slit 44 is for driving a pump or the like.

On the other hand, in recent years, assembling camshafts have been widely adopted to reduce the weight of camshafts. The assembling type camshaft is obtained by mechanically assembling a cam lobe and a hollow shaft for a camshaft, and various structures are known. As a conventional assembling camshaft, for example, a hollow shaft is passed through the inner diameter of a cam lobe with a gap to determine the position and phase of the cam lobe, and then an outer shape (at least partially ) Through which a hollow shaft is expanded to form a camshaft by fixing the hollow shaft and a cam lobe (U.S. Pat. No. 4,781,076, Japanese Patent Publication No. 6-86803).
No.) is known.

[0004]

However, in the conventional assembly type camshaft, the thickness of the hollow shaft is made relatively thin in order to increase the weight reduction effect, so that the pump or the like is driven. For this reason, there is a problem that the pressure receiving area of the slit portion provided on the shaft is reduced, and the mechanical durability of the slit portion is low.

Therefore, in the prior art, the weight of the camshaft and the ability to drive a pump or the like (mechanical durability)
Improvement cannot be achieved at the same time.

SUMMARY OF THE INVENTION The present invention has been made under the above circumstances, and an object of the present invention is to provide an assembled camshaft for an engine which is lightweight and has high mechanical durability for driving a pump or the like. is there.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an assembling camshaft for an engine, comprising a cam lobe member and a cylindrical shaft member connected to each other, and an object of the present invention is to provide an endless end of the cylindrical shaft member. This is achieved by increasing the thickness of the slit portion of the cylindrical shaft member by fastening a cylindrical member to the outer diameter and providing a slit at the fastening portion.

Further, the above object of the present invention is to use a pipe expansion method as a method for fastening the cylindrical member to an end outer shape of the cylindrical shaft member, and to drive the pump through the slit. By having it, it can be achieved more effectively.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the assembled camshaft for an engine of the present invention, the cylindrical member is fastened to the outer diameter of the end of the cylindrical shaft member (portion where the slit is provided) by a pipe expansion method, and the cylindrical member is fastened. Since the slit is provided in the slit portion, the thickness of the cylindrical shape combining the shaft member and the cylindrical member at the slit portion is larger than the thickness of only the shaft member. Therefore, the pressure receiving area of the slit portion is increased and the driving capability (mechanical durability) of the slit portion is increased by the increase in the thickness of the cylindrical shape of the slit portion. Furthermore, in the engine-assembled camshaft of the present invention, the thickness of the shaft member itself can be made smaller than the thickness of the cast camshaft, so that the engine-assembled camshaft is lightweight and has high mechanical durability. A shaft can be realized.

An embodiment of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1A is a partial sectional view showing the structure of an assembled camshaft for an engine according to a first embodiment of the present invention, and FIG. FIG. 3 is a right side view of a main part of the assembled camshaft for an engine. FIG. 2 is a sectional view taken along line XX in FIG. 1B.

In this assembled camshaft for an engine, cam lobes 21 and 22 and a cylindrical member 31 are fastened to a hollow shaft 1 which is a cylindrical shaft member by a pipe expansion method.

FIG. 5 is a sectional view of a main part showing a state in which the hollow camshaft is being assembled by the pipe expansion method. In this example, a state in which the mandrel 10 is pushed through the inside of the inner diameter of the hollow shaft 1 is shown. . The tip of the mandrel 10 has a processing head 11 having a spline-shaped cross section. Here, after determining the phase through the cam lobes 21 and 22 and the cylindrical member 31 with a gap 2 at a predetermined position on the outer shape of the hollow shaft 1, the mandrel 10 is pushed through the inner diameter of the hollow shaft 1. In this case, the individual cam lobes 21 and 22 and the cylindrical member 31 are set on a fixing jig that positions them in advance at desired phases and intervals, and the center axes thereof are the same in order to smoothly push the mandrel 10 through the hollow shaft 1. Aligned on the axis. By pushing the mandrel 10 through the inner diameter of the hollow shaft 1 in this manner, the hollow shaft 1 is expanded at the tip of the tooth of the processing head 11 of the mandrel 10, and the hollow shaft 1 and the cam lobe 2 are expanded.
1, 2 and the cylindrical member 31 can be integrally connected and assembled. In this example, the tube has been expanded to the DD position, and the cam lobe 22 and the cylindrical member 31 are integrally assembled with the hollow shaft 1, but the cam lobe 21 has not been integrally assembled yet. FIG. 6 is a sectional view taken along the line DD. FIG. 6 shows an example in which the cam lobe 22 is provided with an axial groove 22A (eight in this example). In the above description, an example is shown in which the two cam lobes 21 and 22 and one cylindrical member 31 are fixed to the hollow shaft 1. However, the number of cam lobes and the number of cylindrical members are arbitrary, and the cam lobes are attached to the cam lobes. The number of the axial grooves is also arbitrary, and may not be provided.

The cylindrical member 31 and the hollow shaft 1 are provided with slits 4 as shown in FIGS. Slit 4
Is formed by fastening the hollow cylindrical member 31 to the hollow shaft 1 and then processing the hollow shaft 1 and the cylindrical member 31 by milling or the like. Before the hollow shaft 1 and the cylindrical member 31 are fastened to each other, the hollow shaft 1 and the cylindrical member 31 are previously slit, and the hollow shaft 1 and the cylindrical member 31 are fastened to form the slit 4. You may.

The slit 4 is for driving a pump or the like. Further, the slit 4 may be used for driving a generator.

As a result, in the engine-assembled camshaft, the thickness of the slit portion for driving the pump and the like can be increased, and the thickness of the hollow shaft other than the slit portion can be reduced. In addition, it is possible to easily realize a light-weight and highly mechanically durable assembled camshaft for an engine without increasing the number of manufacturing steps.

In the above-described engine camshaft,
The slit 4 is used to fix the camshaft so that it does not rotate or to rotate the camshaft when assembling the timing pulley to the camshaft or performing maintenance of the valve train. It may be used as a portion on which the projection 41a of the special tool 41 having a rod shape as shown is hooked.

(Second Embodiment) Conventionally, when assembling a timing pulley to a camshaft or performing maintenance on a valve train, a wrench is used to prevent the camshaft from rotating, or the camshaft is rotated. It was necessary to hang a spanner on the camshaft to make it work. In a conventional general cast camshaft, a hexagonal portion is formed in a shaft portion at the time of casting, and a spanner hook portion is provided.

In the conventional assembling camshaft, there is no good way to provide a spanner hooking portion on the camshaft, and a hexagonal spanner hooking member 81 milled as shown in FIG. The first method and FIG.
As shown in (1), two parallel planes (90a, 90b, 91) which are directly milled on
a, 91b).

However, the first method has the following problems: (1) the cost is increased; and (2) the weight reduction rate, which is one of the advantages of the assembled camshaft, cannot be improved.

Further, the second method has a problem that it is difficult to secure two planes when the outer shape of the hollow shaft 1 is small and when the thickness of the hollow shaft 1 is small.

FIG. 3A is a side view showing the structure of an assembled camshaft for an engine according to a second embodiment of the present invention, and FIG. FIG.

In this assembled camshaft for an engine, a cam lobe 21 is fastened to the hollow shaft 1 which is a cylindrical shaft member by a pipe expansion method. The hollow shaft 1 is provided with four holes 5. The hole 5 may be formed by drilling or the like after the cam lobe 21 is fastened to the hollow shaft 1 or may be formed by drilling or the like before fastening the cam lobe 21 to the hollow shaft 1.

As shown in FIG. 4, a projection 41a of a special tool 41 is inserted into the hole 5. In this state, a large force can be applied to the hollow shaft 1 in the clockwise direction by pushing the grip portion 41b of the special tool 41 in the direction of the arrow in the drawing.

Thus, in this engine-assembled camshaft, it is possible to prevent the camshaft from turning or to form a portion for turning the camshaft in the camshaft only by making a hole in the hollow shaft. Therefore, a portion corresponding to a conventional spanner hook portion can be formed without affecting the manufacturing process of the camshaft and with a small amount of labor. Further, in this engine-assembled camshaft, since a spanner hook portion in the conventional camshaft is not required, the weight can be reduced as compared with the conventional camshaft.

In the above-described embodiment, the hole 5 is formed in the side surface of the hollow shaft 1. However, the cylindrical member 31 shown in FIG.
Alternatively, the hole 5 penetrating the cylindrical member 31 may be formed. In this way, the thickness of the hole 5 can be increased, so that the mechanical durability of the hole 5 can be improved while suppressing an increase in the weight of the engine-assembled camshaft.

[0027]

According to the present invention, since the cylindrical member is fastened to the outer shape of the end of the shaft member, the thickness of the cylindrical portion at the fastening portion is increased, and the slit is provided at the fastening portion. The pressure receiving area of the slit part increases by the amount
The driving capability (mechanical durability) of the slit portion can be increased.

Furthermore, in the engine-assembled camshaft of the present invention, the thickness of the shaft member itself can be made thinner than the thickness of the cast camshaft, so that it is lightweight and has high mechanical durability. An assembled camshaft can be realized.

[Brief description of the drawings]

FIG. 1A is a partial cross-sectional view showing a structure of an assembled camshaft for an engine according to a first embodiment of the present invention, and FIG. 1B is a right side view of a main part thereof. It is.

FIG. 2 is a sectional view taken along the line XX in FIG. 1 (b).

FIG. 3A is a side view showing a structure of an assembled camshaft for an engine according to a second embodiment of the present invention, and FIG. 3B is a side view of FIG. FIG.

FIG. 4 is an explanatory diagram showing a shape of a special tool used for an assembling camshaft for an engine according to the first or second embodiment of the present invention and a use state thereof.

FIG. 5 is a cross-sectional structural view of a main part showing a state in which a hollow camshaft is being assembled by a pipe expansion method.

FIG. 6 is a sectional view taken along the line DD during camshaft expansion in FIG. 5;

FIG. 7A is a side view showing a structure of a conventional cast camshaft, and FIG. 7B is a right side view thereof.

FIG. 8 (a) is a side view showing a spanner-hanging portion of a conventional assembling camshaft, and FIG. 8 (b) is a sectional view taken along the line AA in FIG. 8 (a).

FIG. 9 (a) is a side view showing another spanner-hanging portion of the conventional assembling camshaft, and FIG. 9 (b) is a sectional view taken along the line BB in FIG. 9 (a). is there.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hollow shaft 4 Slit 5 hole 21, 22 Cam lobe 31 Cylindrical member 41 Special tool

Claims (1)

[Claims] 1. An assembling camshaft for an engine, comprising a cam lobe member and a cylindrical shaft member coupled to each other, wherein the cylindrical member is fastened to an outer diameter of an end of the cylindrical shaft member, and a slit is formed in the fastening portion. An engine-assembled camshaft for an engine, comprising: