JPH11247943A - Crankshaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the vibration and rolling performance effectively without bringing about large-sized construction of a crank case. SOLUTION: A crank journal 2 is coupled with a crankpin 5 through a plurality of crank webs 3, and a circular step 9 is formed on the front end face of at least that crank web 3 which is located at the forefront of a crankshaft 1, and a ring-shaped torsional damper 10 of viscous type having an outside diameter smaller than the outside circumference of the rotational locus of the crankshaft 1 is fitted on the step 9, and thereby the present invention can manage without provision of any particular torsional damper pulley or the like on the axis of the crankshaft 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crankshaft of an internal combustion engine, and more particularly to a crankshaft having a torsion damper in a crankshaft shaft system.

[0002]

2. Description of the Related Art In order to improve the mountability of an engine on a vehicle, it is necessary to reduce the overall length of the engine. On the other hand, in order to suppress the vibration of the crankshaft shaft system, a method of mounting a damper device at the tip of the shaft system is often used, but the length of the crankshaft shaft system becomes longer by the mounting of the damper device. However, it was difficult to shorten the entire length of the engine.

As a countermeasure for this, there is a conventional one disclosed in Japanese Patent Application Laid-Open No. 8-109949.

[0004] As shown in FIG. 3, elasticity is provided circumferentially on both sides of a first crank web (arm) 101 (corresponding to the # 1 (first) cylinder of the engine) of the crankshaft 100. Annular crank angle sensor plate 103 for measuring the crank angle via a metal spring 102 having
Is fixed.

[0005] The crank angle sensor plate 10
In the gap between No. 3 and the first counterweight 104,
Fixed inside the crank angle sensor plate 103,
A friction plate 105 is provided in sliding contact with the counterweight 104, and a relative angle between the crank angle sensor plate 103 and the crank web 101 is limited to a predetermined range on a surface of the crank angle sensor plate 103 facing the crank web 101. Is provided. In the drawing, reference numeral 107 denotes a crank pin, and reference numeral 108 denotes a crank angle sensor.

According to this, the normal crankshaft 10
By disposing the crank angle sensor plate 103 disposed between the timing pulley and the torsional damper pulley at the front end of the counterweight 104 so as to overlap the counterweight 104, the axial length of the crankshaft 100 can be reduced.

Further, since the annular crank angle sensor plate 103 also functions as a damper for torsional vibration of the crankshaft 100, the torsion damper pulley can be eliminated, thereby further increasing the shaft of the crankshaft 100. The length can be shortened.

[0008]

However, in the above-described conventional crankshaft, since a sensor plate having a damper function is provided on the outer peripheral portion of the counterweight, the mass of the inertial body is increased to suppress vibration. In order to increase the rotational speed, it is necessary to increase the rotation trajectory or to extend the space between the crank journals in the direction of the crank axis, and in any case, there is a problem that the size of the crankcase is increased. In addition, there is a problem that the structure is complicated and productivity is not good.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a crankshaft capable of effectively improving vibration damping without increasing the size of a crankcase.

[0010]

According to a first aspect of the present invention, there is provided a crank web arranged at least on the frontmost side of a crankshaft among a plurality of crank webs connecting a crank journal and a crankpin. A circular stepped portion is formed on the front end face of the vehicle, and an annular torsion damper having an outer diameter equal to or less than the outer circumference of the rotation locus of the crankshaft is fitted into the stepped portion.

According to this, the simple structure of fitting the torsion damper to the step portion of the crank web makes it possible to shorten the axial length of the crankshaft while improving the vibration damping performance of the crankshaft and to reduce the size of the crankcase. Can be achieved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A crankshaft according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a side view of a crankshaft showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line II-II of FIG.

As shown, the crankshaft 1 has:
Four crank pins 5 are formed integrally between the crank journals 2 via a crank web (arm) 3 and a counterweight 4 so as to be used for a four-cylinder engine.

The crankshaft 1 has a lubricating oil passage 6 formed therein for supplying lubricating oil to each sliding portion of the crank journal 2 and the crankpin 5, and a camshaft and a camshaft at the front end. A timing gear 7 for driving auxiliary equipment is fixed, and a flywheel 8 is fixed to the rear end.

A circular step 9 is formed on the front end face of the first crank web 3 corresponding to the # 1 (first) cylinder of the engine.
An annular torsion damper 10 having an outer diameter equal to or less than the outer circumference of the rotation locus is fitted by press fitting or the like.

In the illustrated example, the torsion damper 10 is a silicone oil 1 sealed in a damper case 10a.
This is a viscous type damper that attenuates vibration by viscous resistance such as 0b, thereby absorbing and attenuating torsional vibration of the crankshaft 1. The torsion damper 10 is provided with rubber and a mass body. You may comprise a rubber damper.

As described above, the torsional vibration of the crankshaft 1 is suppressed by the torsion damper 10 fitted to the step 9 of the crank web 3, so that the torsional vibration is specially provided on the axis of the crankshaft 1. There is no need to provide a damper pulley, and the axial length of the crankshaft 1 can be shortened accordingly.

In the present embodiment, the outer diameter of the torsion damper 10 is set to be equal to or less than the outer circumference of the rotation locus of the crankshaft 1, so that the crankcase does not increase in size.

Further, in this embodiment, the simple structure in which the torsion damper 10 is fitted to the step portion 9 of the crank web 3 has an advantage that the assembling property and the productivity are high.

It should be noted that the present invention is not limited to the above-described embodiment, and the torsion damper 1 may be used without departing from the gist of the present invention.
Needless to say, various changes are possible, such as fitting 0 to a plurality of crank webs 3.

[0022]

In the crankshaft according to the first aspect of the present invention, of the plurality of crank webs connecting the crank journal and the crank pin, a circular step is formed on the front end face of the crank web disposed at least on the foremost side of the crank shaft. And an annular torsional damper having an outer diameter equal to or less than the outer circumference of the rotation locus of the crankshaft is fitted to the stepped portion. The shaft length of the crankshaft can be reduced and the size of the crankcase can be reduced while improving the performance.

[Brief description of the drawings]

FIG. 1 is a side view of a crankshaft showing one embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view of a conventional crankshaft.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crankshaft 2 Crank journal 3 Crank web 4 Counter weight 5 Crank pin 9 Step part 10 Torsion damper

Claims (1)

[Claims] A circular step is formed on a front end surface of a crank web disposed at least on a foremost side of a crank shaft among a plurality of crank webs connecting a crank journal and a crank pin, and the crank step is formed on the step. A crankshaft having an annular torsion damper having an outer diameter equal to or less than an outer circumference of a rotation trajectory of a shaft.