JPH0821211A - Cam shaft for engine - Google Patents

Abstract

PURPOSE:To provide a cam shaft for an engine, having sufficient stiffness in spite of a hollow cam shaft, and able to be made into a small size and lightweight. CONSTITUTION:In a hollow shaft 6 wherein cam elements 1, 2, 3 are integrally fixed on the outer peripheral surface, and spacers 4, 5 are integrally fixed between the cams, the axial direction of the cam elements is positioned in the width direction of the spacers, and the spacers are pressure-bonded on the hollow shaft 6, thereby required stiffness is given to the cam shaft by the thickness of the spacers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine camshaft used in a reciprocating internal combustion engine or the like, and in particular, a camshaft and bearing elements and other camshaft constituent elements integrally fixed to the outer peripheral surface of a hollow shaft. Regarding improvement of camshaft for engine.

[0002]

2. Description of the Related Art Conventionally, a camshaft for opening / closing an intake / exhaust valve of a reciprocating internal combustion engine or the like has been manufactured by casting a mold and then machining it. In order to improve engine performance by increasing the rotational inertia of the cam shaft itself, there is a cam shaft having a hollow shaft to reduce the weight.

As an example of such a hollow camshaft having a reduced weight, a camshaft structure such as a cam element and a journal element, such as an engine camshaft disclosed in Japanese Patent Laid-Open No. 125506/1989, is disclosed. The elements are made of wear-resistant materials as individual parts, and the hollow shaft is inserted through the axial hole to position them at the prescribed phase and axial spacing, and then the hollow shaft is expanded radially outward. There is a cam shaft that is light in weight by fixing these cam shaft components to a hollow shaft and assembling them integrally.

In the conventional cam shaft, as shown in FIG. 6, an assembling jig is used in order to position each constituent element at a predetermined phase and at a gap in the axial direction and integrally assemble it. 1, 2,
Reference numeral 3 is a cam element, 11 is an axial positioning jig, and 12 is a circumferential direction phasing jig, which shows an assembled state of a main part of the cam shaft.

On the other hand, a torsional moment from each cam element and a bending moment from a camshaft driving member act on the camshaft, and their magnitudes differ depending on the axial portion of the camshaft. A large torsional moment and a large bending moment act on the cam shaft portion on the driven member side, which is usually attached to one end portion of the cam shaft.

[0006]

As described above, the hollow cam shaft, which has been reduced in weight, is required to have an axial positioning accuracy when the respective constituent elements are arranged in the axial direction and integrally assembled. When the axial spacing of the components is narrow, the thickness of the plate jig of the assembly machine that determines the axial positions of them is also small, so the strength and durability are reduced, and the axial positioning by the assembly machine plate jig is reduced. It will be difficult.

On the other hand, the wall thickness of the steel pipe used for the hollow cam shaft must be expandable, so that it is limited to a certain thickness. Therefore, it is impossible to cope with a material requiring large torsional rigidity and bending rigidity with this thin wall thickness.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems. Even in a camshaft which has a small axial distance between the camshaft constituent elements and is miniaturized, it is easy to assemble and has sufficient rigidity. , And to provide a camshaft for an engine that is easy to reduce in size and weight.

[0009]

SUMMARY OF THE INVENTION The above object of the present invention is to provide an engine camshaft having a plurality of camshaft components integrally fixed to the outer peripheral surface of a hollow shaft, and a spacer between the camshaft components. It is achieved by a camshaft for an engine, characterized in that

[0010]

According to the present invention, a spacer having a predetermined width is mounted between the components arranged on the outer peripheral surface of the hollow shaft at a required position without any gap, and the space is pressed and brought into close contact with the hollow shaft. No assembly plate jig for positioning is required. Further, the rigidity of the camshaft as a whole can be provided by arbitrarily setting the wall thickness of the spacer, and the size and weight of the camshaft can be reduced by reducing the portion having a wall thickness larger than necessary.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an engine camshaft according to the present invention will be described in detail below with reference to the accompanying drawings. 1 and 2 are
FIG. 1 is an external view showing a camshaft for an engine according to a first embodiment of the present invention and a sectional view of a main part at the time of assembly.

An engine camshaft 10 according to the present invention shown in FIG. 1 is a camshaft used in a V-type 6-cylinder engine, and has a hollow shaft 6 formed of a hollow tube and a predetermined interval in the axial direction of the hollow shaft 6. The camshafts 1, 2 and 3 which are camshaft constituent elements fixed to the outer peripheral surface, the spacers 4 and 5 which also function as journals which are bearings, and the nosepiece 7 fixed to the left end side of the hollow shaft 6 in the drawing are provided. There is.

FIG. 2 is a sectional view of a main part of the cam shaft 10 during assembly, showing an axial positioning plate 11 and a circumferential phasing plate 12 for the cams 1, 2 and 3 as an assembly jig. There is.

The spacers 4, 5 are in close contact with the respective cams 1, 2, 3 without any gap in the axial direction, and by setting their axial dimensions to predetermined values, the cams 1, 2, It becomes possible to perform the axial positioning of No. 3. Further, since the spacers 4 and 5 are brought into close contact with the hollow shaft 6 under pressure, the wall thickness of the hollow shaft 6 is substantially increased, the rigidity thereof is increased, and the torsion moment applied to the hollow shaft 6 and It becomes possible to give a sufficient rigidity to the bending moment.

Therefore, the camshaft 1 which is required to be small and lightweight.
At 0, even if a thick axial positioning plate having a narrow cam element spacing and a required strength cannot be used as an assembly jig, it can be easily assembled by the spacers 4 and 5 and only the necessary parts are provided. By adjusting the wall thickness of the spacer, it is possible to provide a small and lightweight cam shaft having sufficient rigidity.

FIGS. 3 and 4 are an external view and a transverse sectional view showing an engine camshaft according to a second embodiment of the present invention. The engine camshaft 20 has a space between all the camshaft components including the nosepiece 7 without any gaps between the spacers 4, 5, 5.
14, 15, 16 are closely attached. Also, as mentioned above, all camshaft components and all spacers are hollow shafts 6.
Is pressed and closely attached to the outer peripheral surface of the.

Therefore, all the camshaft components except the nosepiece 7 do not require an axial assembly jig, and the desired axial positioning can be performed by setting the spacer to a predetermined width dimension. Further, by appropriately setting the thickness of each spacer, it is possible to give the camshaft 20 a predetermined rigidity. In addition, it is obvious that the required place spacer can also serve as the journal element.

FIG. 5 is a transverse sectional view showing an engine camshaft according to a third embodiment of the present invention. In this engine camshaft 30, the spacers 17, 18, 19 inserted between the cam elements on the side of the nosepiece 7 are thick, and the spacers 21, 22, 2 inserted between the cam elements in the central portion.
The wall thickness of 3 is thin, and a spacer is not inserted between the cam elements on the right side of the drawing.

In this camshaft, a desired camshaft rigidity can be obtained by relatively increasing the thickness of the spacer on the camshaft driving side, which requires relatively large torsional rigidity and bending rigidity. Further, the spacer may be inserted only on the camshaft driving side 17, 18, and 19.
It is also possible to change the wall thickness of each of 18 and 19 to obtain a desired camshaft rigidity.

The spacers are arranged in the axial direction without any gap when they are pressed and closely attached to the hollow shaft, but there may be a gap of about 0.5 or less in the axial direction depending on the material flow at the time of expanding the hollow shaft. As described above, it is possible to provide a small and lightweight camshaft having sufficient rigidity for a camshaft that is required to be further reduced in size and weight.

[0021]

According to the camshaft for an engine of the present invention, a spacer having a predetermined width is closely attached in the axial direction between the camshaft constituent elements having a narrow axial distance, so that the shaft of the camshaft constituent element is provided. Directional positioning is possible, and sufficient rigidity can be provided by press-contacting the spacer with the hollow shaft and setting the thickness appropriately. Therefore, it is possible to provide a camshaft for an engine which is a hollow camshaft but has sufficient rigidity and which can be reduced in size in the axial direction and which can be easily reduced in size and weight.

[Brief description of drawings]

FIG. 1 is an external view of a camshaft for an engine according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part when assembling the first embodiment.

FIG. 3 is an external view of an engine camshaft according to a second embodiment of the present invention.

4 is a cross-sectional view of the engine camshaft shown in FIG.

FIG. 5 is a transverse cross-sectional view of an engine camshaft according to a third embodiment of the present invention.

FIG. 6 is a cross-sectional view of a main part at the time of assembling a conventional example.

[Explanation of symbols]

1, 2, 3 cam elements 4, 5, 14, 15, 16, 17, 18, 19, 21,
22, 23 Spacer 6 Hollow shaft 7 Nose piece 11 Axial positioning jig 12 Circumferential phasing jig 10, 20, 30 Engine camshaft

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Osawa 1-8-1, Sojamachi, Maebashi City, Gunma Nippon Seiko Co., Ltd.

Claims (1)

[Claims] 1. A camshaft for an engine in which a plurality of camshaft constituent elements are integrally fixed to an outer peripheral surface of a hollow shaft, and a spacer is provided between the camshaft constituent elements with substantially no space. Camshaft for the engine.