JPH0321800Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention relates to a cast shaft-shaped member formed by casting such as a cast crankshaft or a cast camshaft. This invention relates to a cast shaft-shaped member that is made lighter and has improved strength by being cast.

(Prior technology) Casting has advantages such as easy molding, a large degree of freedom in design, and a large vibration damping capacity of the molded product, and shaft-like members such as crankshafts and camshafts that are produced in large quantities are cast by casting. The aim is to reduce costs by manufacturing. Cast shaft-shaped members manufactured by such casting are generally hollowed out by casting in order to reduce their weight, and a hole with a circular cross-section or a hole concentric or eccentric in the shaft-shaped part is formed. An elliptical hollow hole is formed.

(Problems to be solved by this invention) However, in the case of the conventional cast shaft member mentioned above, the bending rigidity is reduced by casting out the hollow hole, so dynamic unbalance occurs during high speed rotation etc. There was a problem in that deflection occurred due to this, and uneven wear occurred in the bearing portion, which caused problems such as tapping noise.

This idea was created in view of the above-mentioned problems, and aims to provide a cast shaft member that is lightweight without reducing rigidity, and to prevent problems such as uneven wear. .

(Means for Solving the Problems) This invention provides a cast shaft-like member such as a camshaft in which a hollow hole has a shaft-like portion formed by casting. The gist is that continuous unevenness is integrally formed.

(Function) According to the cast shaft-shaped member according to this invention, since the irregularities are continuously formed in the axial direction on the peripheral wall of the hollow hole, the bending rigidity is increased, and the deflection that occurs during high-speed rotation can be reduced. As a result, the bearing portion does not wear unevenly, and problems such as tapping noise can be prevented. Furthermore, since the unevenness can be formed without affecting the shape of the outer circumferential surface, the cam face of a cam such as a camshaft is not subject to any restrictions, and a great advantage can be obtained in terms of design, etc.

(Example) Hereinafter, an example of this invention will be described based on the drawings.

Figures 1 and 2a and 2b show an embodiment in which this invention is applied to a cast crankshaft, which is a cast shaft-like member, in which Figure 1 is an overall view, Figure 2a is a partially enlarged sectional view, FIG. 2b is a sectional view taken along the - arrow in FIG. 2a.

In the figure, 11 represents a cast crankshaft, and this crankshaft 11 has a journal part 12, a crank pin part 13, and a balance weight part 14, all of which are integrally molded by casting. As shown in detail in FIGS. 2a and 2b, the journal part 12
A hollow hole 12a is formed by casting, and similarly,
A hollow hole 13a is formed in the crank pin portion 13 by casting. In each journal portion 12, a concave and convex portion 15 (in the figure, only the convex is indicated by a reference numeral) is formed on the peripheral wall of the hollow hole 12a, and continues over the entire circumference and the entire length. The pin portion 13 has an unevenness 16 (in the figure,
Only the convex portion is marked with a symbol).

In this cast crankshaft 11, the journal part 12 and the crank pin part 13 are cast out to form the hollow holes 12a, 13a, so that the weight is small and lightweight. The peripheral walls of these hollow holes 12a and 13a have irregularities 15 and 16.
is formed, so the cast crankshaft 1
1 increases the overall bending rigidity. Therefore,
Even if the cast crankshaft 11 rotates at high speed, the deflection is small, and the journal part 12, the sliding bearing part of the cylinder block that comes into sliding contact with the journal part 12,
Crank pin portion 13 and the crank pin portion 13
The sliding bearings of the connecting rods that come into sliding contact with the connecting rods will not suffer uneven wear, and problems such as tapping noise will not occur. Further, the unevenness 15 and 16 can be formed without affecting the shape of the outer peripheral surface of the crankshaft 11, that is, without changing the shape of the outer peripheral surface.
Design freedom is not compromised.

According to the inventor's experiments, the cast crankshaft 1 according to this embodiment, as shown in FIG.
1 has load-deflection characteristics, that is, rigidity, as shown by the solid line in the figure, which is larger than the conventional hollow crankshaft shown by the dashed-dotted line in the figure, and equivalent to the solid crankshaft shown by the dashed-dot line in the figure. It has been confirmed that it has rigidity.

4 and 5a and 5b show an embodiment in which this invention is applied to a camshaft as a cast shaft member. Figure 4 is an overall view of the camshaft, Figure 5
Figure a is a partially enlarged view, and Figure 5 b is the − of Figure 5 a.
It is an arrow sectional view.

As shown in the figure, the camshaft 21 has a shaft portion 22 and a plurality of cams 23 arranged in the axial direction on the outer circumference of the shaft portion 22, and these shaft portions 22 and cams 23 are integrally formed by casting. is formed into. A hollow hole 22a having a substantially circular cross section is formed by casting in the shaft portion 22, and a concave and convex portion 24 (in the figure, only the convex portion is denoted by a symbol) is formed on the circumferential wall of the hollow hole 22a. ) is formed.

Even in this camshaft 21, the hollow hole 22
a is cast out to reduce the weight, and the hollow hole 2
The overall bending rigidity is increased by the unevenness 24 on the peripheral wall 2a. Therefore, the degree of freedom in design is not reduced, and the camshaft 21 is less deflected during high-speed rotation, thereby preventing uneven wear that causes hammering sounds and the like.

In addition, in each of the embodiments described above, the hollow holes 12a,
Rectangular unevenness 15, 1 on the peripheral wall of 13a, 22a
6 and 24 are formed, but the unevenness is not limited to a rectangular shape, and it goes without saying that the present invention can be achieved with a spline-like unevenness, etc., as long as the shape increases the moment of inertia.

(Effects of the invention) As explained above, according to the cast shaft-shaped member according to the invention, a hollow hole is cast out and irregularities continuous in the circumferential direction and the axial direction are integrally formed on the inner circumferential wall of the hollow hole. Therefore, the bending rigidity can be increased without increasing the weight and without losing freedom in determining the external shape.

[Brief explanation of the drawing]

1 to 3 show an embodiment of this invention, in which FIG. 1 is an overall view of a crankshaft as a cast shaft-like member, FIG. 2a is a partially enlarged sectional view, and FIG.
Figure b is a sectional view taken along the - arrow in Figure 2a, and Figure 3 is a load-deflection characteristic diagram. 4 and 5 show other embodiments of this invention, in which FIG. 4 is an overall view of a camshaft as a cast shaft member, FIG. 5a is a partially enlarged sectional view, and FIG. 5b is a camshaft. FIG. 5 is a sectional view taken along the - arrow in FIG. 5a. 11... Crankshaft (cast shaft member),
12a, 13a, 22a...Hollow hole, 15, 1
6, 24... unevenness, 21... camshaft (cast shaft-shaped member).

Claims (1)

[Scope of Claim for Utility Model Registration] In a cast shaft-like member such as a crankshaft or camshaft having a shaft-like portion in which a hollow hole is formed by casting, the inner circumferential wall of the hollow hole has a circumferential direction and an axial line of the hollow hole. A cast shaft-shaped member characterized by integrally forming unevenness continuous in the direction.