JPH0244092Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a flywheel mounting device for internal combustion engines, particularly for small internal combustion engines.

(Prior Art) FIG. 1 shows an example of a flywheel mounting device for a small gasoline engine.

In the figure, reference numeral 1 denotes a flywheel, and a tapered hole having a keyway 1a is provided in the center of the flywheel. Reference numeral 3 denotes a crankshaft, and a keyway 3a that fits the key 2 is provided in the tapered portion of the shaft end, and the keyway 1a of the flywheel 1 is fitted into the key 2 held in this keyway 3a. The flywheel 1 is inserted into the shaft end of the crankshaft 3, and the flywheel is attached by tightening with a nut 4.

(Problem to be Solved by the Invention) However, in the conventional device described above, in addition to providing the keyways 1a and 3a in the flywheel 1 and the crankshaft 3, respectively, these keyways 1a,
3a must be manufactured separately, and the key 2 must be assembled manually, making it difficult to automate engine manufacturing and increasing the number of parts. There was a problem that the manufacturing cost was high.

Therefore, as shown in Japanese Utility Model Application Publication No. 57-145823, a key-shaped protrusion is integrally formed on the inner circumferential surface of the tapered hole of the flywheel over the entire length in the axial direction, and the key is manufactured separately. A proposal has been made to make it unnecessary. However, with such a configuration, the key-shaped protrusion of the flywheel is formed over the entire length of the inner circumferential surface of the tapered hole, making it impossible to perform machining on the inner circumferential surface of the tapered hole. There was a problem that the fitting was poor and the anti-slip torque was reduced.

The present invention was proposed to solve these problems. It eliminates the need for a key, simplifies the flywheel installation work, reduces manufacturing costs, and connects the flywheel and crankshaft. It is an object of the present invention to provide a flywheel mounting device that can increase the reliability of anti-slip torque in a fitting part.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the flywheel mounting device according to the present invention is provided with a tapered part at the end of the crankshaft, and a tapered part formed in the center of the flywheel. In a flywheel mounting device for mounting a flywheel by fitting a tapered hole into the flywheel, a key is provided on the inner circumferential surface of the tapered hole of the flywheel and extends along the axial direction over a part of the axial length from the small diameter end of the flywheel. A shaped protrusion is formed integrally with the flywheel, and a key groove is formed in the tapered shaft end of the crankshaft, and the key shaped protrusion of the flywheel is fitted into the key groove to crank the flywheel. It is characterized by being fixed to the shaft.

(Function) Since the present invention has the above-mentioned configuration, the flywheel can be easily installed by directly fitting the key-shaped protrusion formed integrally with the flywheel into the keyway of the crankshaft. It can be positioned and fixed to the crankshaft.

In addition, the key-shaped protrusion is formed on the inner circumferential surface of the tapered hole of the flywheel so that it extends along the axial direction from the small diameter end, so that it extends along the axial direction from the small diameter end. It becomes possible to easily machine the portion of the peripheral surface where the key-shaped protrusion is not formed.

(Example) An example of the present invention will be described below with reference to FIG.

In the figure, 3 is a crankshaft, and a keyway 3a is provided in the tapered portion of the shaft end. 4 is a nut for tightening and fixing the flywheel, 10 is a flywheel fixed to the shaft end of the crankshaft 3, and the flywheel 10 has a tapered hole in the center that fits into the tapered part of the shaft end of the crankshaft 3. 10a is bored.

Inside this tapered hole 10a, a key-shaped protrusion 11 extending along the axial direction from the small diameter end side to a part of the axial length L is provided on the inner peripheral surface of the flywheel 10. The key-shaped protrusion 11 has an upper surface 11a left as a cast surface, and both side surfaces 11b can be machined.

Further, the tapered hole 10a has a key-shaped protrusion 11.
It is possible to machine the inner circumferential surface of the L- portion where no is formed.

When attaching the flywheel 10 configured as described above to the crankshaft 3, the flywheel 10 is attached to the crankshaft 3 while the key-shaped protrusion 11 of the flywheel 10 is fitted into the keyway 3a of the crankshaft 3.
Press fit and tighten with nut 4. This results in
The positioning of the flywheel 10 is also ensured,
The flywheel 10 can be firmly tightened and fixed.

FIG. 3 shows another embodiment of the present invention.

In the case of this embodiment, a female thread 3b is machined at the shaft end of the crankshaft 3, and a bolt 13 is screwed into this to tighten and fix the flywheel 10. The configuration of the tapered hole 10a, key-shaped protrusion 11, etc. of the flywheel 10 is the same as that shown in FIG.

(Effect of the invention) As explained above, according to the flywheel mounting device according to the invention, the key-shaped protrusion formed integrally with the flywheel is directly fitted into the keyway of the crankshaft. Since the flywheel can be easily positioned and fixed on the crankshaft, it is possible to automate flywheel assembly work, and since a key is not required, keyway machining of the flywheel is no longer necessary, and the number of parts and machining can be reduced. The number of man-hours is also reduced, and the manufacturing cost of the engine can be reduced.

In addition, since the key-shaped protrusion of the flywheel is formed only on a part of the axial length of the tapered hole, it is possible to perform machining on the inner circumferential surface of the taper hole where the key-shaped protrusion is not formed. As a result, it is possible to improve the contact between the tapered hole and the tapered fitting portion of the shaft end of the crankshaft, and improve the reliability with respect to slip torque resistance.

[Brief explanation of drawings]

Figures 1a and 1b are cross-sectional views showing an example of a flywheel mounting device for a conventional small internal combustion engine;
Figures a to c show one embodiment of the present invention, in which a is a cross-sectional view along the crankshaft center line, b is a cross-sectional view of the main part of the flywheel, c is a view taken along arrow C in b, and Figures 3a and b 2 shows another embodiment, in which a is a cross-sectional view taken along the crankshaft center line, and b is a cross-sectional view of a main part of the flywheel. 3: crankshaft, 3a: keyway, 10: flywheel, 10a: tapered hole, 11: key-shaped protrusion.

Claims (1)

[Scope of utility model registration request] In a flywheel mounting device for attaching a flywheel by providing a tapered part at the shaft end of a crankshaft and fitting a tapered hole formed in the center of the flywheel into the tapered part, the inner periphery of the tapered hole of the flywheel is provided. A key-shaped protrusion extending along the axial direction over a part of the axial length from the small diameter end is formed integrally with the flywheel on the surface, and a key groove is formed in the tapered portion of the shaft end of the crankshaft. A flywheel mounting device characterized in that the flywheel is fixed to the crankshaft by fitting the key-shaped protrusion of the flywheel into the key groove.