JP2000297845A - Balancer shaft for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mitigate edge contact and to effectively reduce vibration by supporting journal portions formed near the eccentric masses at both end portions of a balancer shaft with bearings, and forming the journal portions into a partial tapered face. SOLUTION: Both end sections of a balancer shaft 1 are supported by bearings 2, and eccentric masses 3 are provided in opposite directions at both ends. A partial taper 5 is formed on each journal section 4, the taper angle αis set to the maximum tilt angle of the shaft 1, and the length of a partial tapered face is set to 30-100% of the length of the journal section 4. When the angle αis large, a stripe may occur at the boundary between a tapered section and an untapered portion, therefore a cross section is formed into a circular arc shape to prevent it so that no damage is applied to the bearing 2 side. The edge contact of the journal sections 4 with the bearings 2 caused by inclination when the shaft 1 is rotated can be mitigated, and the durability of the shaft 1 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balancer shaft of an internal combustion engine provided for suppressing vibration generated by a reciprocating mass of the internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine having a small number of cylinders, a balance shaft is provided on both sides of the crankshaft in parallel with the crankshaft, and the balance shaft is rotated in synchronization with the crankshaft. There has been proposed a balancer shaft for an internal combustion engine that suppresses generated vibration.

This balancer shaft uses a balancer shaft whose frequency is adjusted to primary vibration in a three-cylinder internal combustion engine, and to secondary vibration in a four-cylinder internal combustion engine, and uses a balancer shaft having the same frequency. It is configured to reduce the order vibration.

The balancer shaft 1 of this vibration reducing device
As shown in FIG. 3 in which the gap between the bearing and the journal portion is exaggeratedly drawn, two journal portions near both ends are supported by the bearing 2 and the eccentric shape is formed on both ends of the balancer shaft 1. An eccentric mass 3 is provided.

Therefore, in the balancer shaft 1 as described above, the journal portion which comes into contact with the bearing 2 due to the whirling of the eccentric mass 3 supports the load at the edge portion indicated by the arrow X near the eccentric mass 3 as shown in FIG. As a result, a local load is generated, which is disadvantageous in durability due to wear of the bearing 2 portion.

On the other hand, Japanese Patent Application Laid-Open No. 5-164190 proposes an invention relating to a balancer device for an engine.
Are supported by two bearings 15 and 16, and balance masses 13 and 14 are arranged so as to extend on both sides of one bearing 16,
Balance mass 13 located between bearings 15 and 16 of first journal portion 11 and second journal portion 12, respectively.
The component is larger than the unbalance component of another balance mass 14 extended outward from the bearing 16, and the inclination of the balance shaft 10 at the position of the bearing 16 between the two balance masses 13 and 14 is substantially zero. I am trying to be.

That is, by making the unbalance component of the first balance mass 13 larger than the unbalance component of the second balance mass 14, the second journal portion 1
2, the inclination of the balance shaft 10 becomes almost zero, and the occurrence of problems such as one-sided contact, uneven wear and seizure in the second bearing 16 is prevented.

However, in the prior art according to the present invention, skill is required to make the unbalance component of the first balance mass 13 component larger than that of the other second balance mass 14. Above, there is a problem that it is difficult to perform vibration isolation over the entire range of the rotational speed of the internal combustion engine.

[0009]

SUMMARY OF THE INVENTION As shown in an exaggerated manner in FIG. 3, the present invention locally contacts a bearing caused by the whirling of an eccentric mass in a small area of a journal portion, thereby causing one-sided contact, uneven wear and the like. The problem that seizures cannot be avoided,
As shown in FIG. 4, balance masses are arranged on both sides of one of the two bearings supporting the balance shaft.
It is an object of the present invention to provide a balance shaft for an internal combustion engine that can solve the problem of having to adjust two eccentric weights in a complicated process at once, and can reduce the edge contact and effectively reduce the vibration. is there.

[0010]

A balance shaft for an internal combustion engine according to the present invention is formed near an eccentric mass provided at both ends of the balance shaft in a balancer shaft provided parallel to a crankshaft of the internal combustion engine. The journal portion is supported by bearings, and the journal portion is formed on a partially tapered surface.

In a balancer shaft provided in parallel with a crankshaft of an internal combustion engine, journal portions formed near eccentric masses provided at both ends of the balance shaft are supported by bearings. It is characterized in that the eccentric mass side is formed on a partially tapered surface that is reduced.

Further, the partial tapered surface is characterized in that its cross section is formed in an arc shape. Further, the partial tapered surface is formed at about 30 to 100% of the length of the journal portion.

By forming the journal portion on a partially tapered surface as described above, even if the balance shaft whirls, it is supported in a planar manner by the bearing, and the durability of the journal portion can be improved. .

The "partial tapered surface" in the present invention is defined as:
Instead of forming the entire length of the journal portion on a tapered surface, the journal portion where the edge contact is most likely to occur is formed on the tapered surface, and the remaining portion is left as a rod shape, The width of the portion not formed is not so large.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a balancer shaft according to the present invention will be described with reference to the drawings. FIG. 1 shows a schematic side view of a main part of a balancer shaft 1 according to one embodiment. This balancer shaft 1 is supported at two positions at both ends by bearings 2 as in the conventional device of FIG. Eccentric masses 3 are provided at both ends of the balancer shaft 1, respectively.
Are provided in the opposite direction.

Therefore, in this embodiment of the present invention, the journal portion 4 supported by the bearing 2 of the balancer shaft 1 is provided.
In FIG. 2, the partial taper 5 is formed by deleting a portion shown by hatching for convenience.

By partially tapering a part of the journal portion 4 as described above, as shown in the conventional example of FIG.
Since the edge of the eccentric mass 3 or the end of the journal portion is not locally supported by the bearing 2 and the contact pressure receiving area increases, the durability due to wear can be improved.

Next, as described above, the partial taper 5 applied to the journal portion 4 is reduced in diameter toward the eccentric mass 3 formed at both ends of the balancer shaft 1, and the taper angle of the partial taper 5 α is the maximum inclination angle of the balancer shaft 1.

Although the partial taper 5 depends on the diameter of the journal portion 4, the taper portion A is preferably selected to be 30 to 100% of the length B of the journal portion 4 shown in FIG.

When the partial taper has a large taper angle α, a streak may be formed at the boundary between the tapered portion and the portion without the taper. Therefore, in order to prevent this, the cross section is formed in an arc shape. Care should be taken not to damage the bearing side.

[0021]

According to the present invention described above, the journal portion supported by the bearing of the balancer shaft is tapered by providing a partial taper, so that the journal caused by the inclination generated in the journal portion when the balancer shaft rotates. It is possible to reduce the contact of the bearing with the edge, reduce the gap between the balancer shafts, and improve the durability of the balancer shaft.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a main part of a balancer shaft according to an embodiment of the present invention.

FIG. 2 is a side view of an enlarged main part of a journal portion of the balancer shaft of FIG. 1;

FIG. 3 is a schematic side view of a main part of a conventional balance shaft.

FIG. 4 is a modified mode diagram of a balancer device in which a conventional balance shaft according to another known invention is mounted on a bearing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Balancer shaft 2 Bearing 3 Eccentric mass 4 Journal part 5 Partial taper

Claims (4)

[Claims] In a balancer shaft provided parallel to a crankshaft of an internal combustion engine, journal portions formed near eccentric masses provided at both ends of the balance shaft are supported by bearings. A balancer shaft for an internal combustion engine formed on a partially tapered surface. 2. A balancer shaft provided parallel to a crankshaft of an internal combustion engine, wherein journal portions formed near eccentric masses provided at both end portions of the balance shaft are supported by bearings. 2. The balancer shaft for an internal combustion engine according to claim 1, wherein said eccentric mass side is formed on a partially tapered surface that reduces. 3. The balancer shaft for an internal combustion engine according to claim 1, wherein said partially tapered surface is formed in an arc-shaped cross section. 4. The balancer shaft for an internal combustion engine according to claim 1, wherein said partially tapered surface is about 30 to 100% of a length of a journal portion.