JPH0724691Y2 - Balancer axis - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of Invention] <Industrial Application Field> The present invention relates to a balancer shaft for canceling vibration of a reciprocating piston engine, and more particularly to a balancer shaft improved to improve lubrication efficiency. .

<Prior Art> Some types of reciprocating piston engines generate unbalanced vibrations due to the movement of the pistons. As a means for removing this vibration, it is known to rotate a balancer shaft having an unbalanced weight that balances the inertial weight of the piston in synchronization with the crankshaft (see Japanese Patent Laid-Open No. 61-84434). .

On the other hand, in order to supply lubricating oil to the bearing portion of these balancer shafts, a structure in which an oil groove is provided on the outer peripheral surface of the journal portion of the balancer shaft that slides in the bearing hole is disclosed in Japanese Utility Model Publication No. 62-14436. Has been done.

<Problems to be Solved by the Invention> Now, the balance weight portion for giving the above-mentioned unbalanced weight is formed eccentrically with respect to the rotation center of the balancer shaft. In the case of the rotating shaft having the eccentric center of gravity, it is inevitable that whirling occurs in which the maximum load point moves along the inner circumference of the bearing hole. It is known that the directions of whirling are opposite to each other when solid friction between the shaft and the bearing hole is involved and when an oil film is interposed (see Kyoritsu Publishing, Mechanics). Is not desirable because it causes a significant decrease in the allowable rotation speed.

However, according to the above conventional lubrication structure, since the lubricating oil discharge port only opens to the surface of the journal portion on the side opposite to the load side, there is a tendency for the amount of lubricating oil in the inner circumference opposite to the discharge port to become insufficient. Can be considered.

On the other hand, the contact area between the journal portion of the balancer shaft and the bearing hole supporting the journal portion is preferably as small as possible in order to reduce friction loss. However, in the case of a balancer shaft having an eccentric weight, it is difficult to reduce the contact area because the surface pressure due to the centrifugal load on the center of gravity must be taken into consideration.

The present invention was devised to address such problems, and its main purpose was to improve the formation of a lubricating oil film effectively and to improve friction loss. To provide a balancer axis.

[Means for Solving the Problems] <Means for Solving the Problems> According to the present invention, the lubricating oil is supplied to the clearance between the journal portion and the bearing hole, and at the position eccentric from the rotation center. A balancer shaft having a center of gravity and a lubricating oil holding groove formed on the outer peripheral surface of the journal portion on the side opposite to the center of gravity, wherein the circumferential center position of the lubricating oil holding groove passes through the center of gravity of the balancer shaft. This is achieved by providing a balancer shaft which is characterized in that it is eccentrically distributed in the direction opposite to the radial line. In particular, the lubricating oil holding groove may be formed so that the width on the side opposite to the center of gravity is widest and gradually narrows toward the circumferential end.

<Operation> According to such a configuration, the circumferential end of the lubricating oil holding groove in the anti-rotation direction is extended to the maximum load point side. When an oil film is present, the whirling direction matches the rotation direction of the shaft, so by bringing the circumferential end in the counter-rotation direction closer to the maximum load point, it is possible to refuel quickly and reliably to the maximum load point. can do.

Further, by increasing the groove width of the journal portion on the side opposite to the center of gravity, the mutual contact area between the journal portion and the bearing hole can be reduced within a range where the surface pressure is allowed, and thus friction loss can be reduced. Moreover, since the groove width becomes narrower as it approaches the maximum load point, the mutual contact area between the journal part and the bearing hole gradually increases even if the groove end is approached to the maximum load point, so the surface pressure balance on the center of gravity side Can be adjusted appropriately.

<Embodiment> Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a balancer shaft 1 to which the present invention is applied. The balancer shaft 1 is for canceling the primary inertia couple of the in-line 5-cylinder engine, and has a pair of eccentric weight portions 2a and 2b whose center of gravity positions are symmetrically arranged with respect to the center of rotation, and both of them. The eccentric weight part 2a and the connecting shaft part 3 for connecting the 2b are formed integrally with each other. Further, one end of the balancer shaft 1 extends so as to project from the end face of the cylinder block 4 in the cylinder row direction, and the end portion thereof is connected to the crank shaft via a winding transmission mechanism (not shown).

Journal portions 7 that fit into bearing holes 6 formed in the journal wall 5 of the cylinder block 4 are formed at both ends of the eccentric weight portions 2a and 2b in the axial direction. That is, in the case of this balancer shaft 1, it is supported by the cylinder block 4 at four points.

As shown in FIG. 2, each journal portion 7 of the balancer shaft 1
On the outer peripheral surface on the side opposite to the center of gravity in FIG. The center position of the lubricating oil holding groove 8 in the circumferential direction is slightly displaced in the counter-rotational direction with respect to the radial line passing through the center of gravity of the balancer shaft.
As a result, one end of the lubricating oil holding groove 8 is brought close to the maximum load point P.

By the way, the whirling direction of the eccentric shaft, in which the oil film is interposed between the shaft and the bearing hole, coincides with the rotation direction of the shaft, and the bearing hole is formed by unevenly distributing the lubricating oil holding groove 8 as described above. The lubricating oil received in the lubricating oil holding groove 8 from the lubricating oil discharge passage 9 opened on the inner surface of 6 flows through the clearance between the bearing hole 6 and the journal portion 7 in the direction opposite to the rotating direction of the balancer shaft 1, Since the maximum load point P is reached early, it is possible to preferably prevent the oil film from being interrupted.

Forming the lubricating oil holding groove 8 up to the position where the maximum load point P is reached is achieved by setting the maximum load point P in the journal portion 7.
Since the area on the side is reduced and the surface pressure of the same portion is increased, it is necessary to appropriately set the angle α between the maximum load point P and the end of the lubricating oil holding groove 8, but find an optimum value. It is not so difficult.

Further, the cross-sectional shape of the end portion of the lubricating oil holding groove 8 is gradually deepened from the outer peripheral surface as shown in FIG. This is a measure to ensure that the lubricating oil flows out without any resistance, and the angle β
Should be set in the range of 5 to 50 degrees.

FIG. 4 shows an expanded outline of the lubricating oil holding groove 8. As is clear from this figure, this groove width is widest on the opposite side of the maximum load point and gradually narrows toward the circumferential end. By doing so, the effective area of the journal portion 7 is suitably adjusted in accordance with the bearing load,
The balance of surface pressure and the reduction of friction loss can both be achieved at a higher level.

The balancer shaft 1 is usually formed by casting or forging. In this case, the split type is used, but the setting of the parting line becomes a problem. This is because, depending on the relationship between the cross-sectional shape of the eccentric weight portions 2a and 2b and the lubricating oil holding groove 8, it becomes difficult to perform die cutting or secondary processing is required. This is because the shapes of the eccentric weight portions 2a and 2b can be changed by setting the parting lines PL to the positions indicated by the imaginary lines with respect to the shapes of the eccentric weight portions 2a and 2b as shown in FIGS. Die cutting is not hindered, and the lubricating oil holding groove 8 is parting line PL.
You can prevent it from happening.

[Advantages of the Invention] As described above, according to the present invention, the formation of an oil film at the maximum load point of the bearing hole is promoted, and the lubrication efficiency and the journal cooling efficiency can be improved. Therefore, the permissible rotation speed is increased, and a great effect can be exerted in improving durability and reliability. In addition, since the effective area of the journal part can be reduced without impairing the surface pressure balancer on the maximum load point side, friction loss is reduced,
It also has the effect of improving output and fuel efficiency.

[Brief description of drawings]

1 is a partial front view of a balancer shaft to which the present invention is applied, FIG. 2 is a sectional view taken along line II-II in FIG. 1, and FIG. 3 is FIG. It is an enlarged view of part A of
FIG. 4 is a development view of the lubricating oil holding groove. 5 to 7 are cross-sectional views of balancer shafts showing modified examples. 1 …… balancer shaft 2a ・ 2b …… eccentric weight part 3 …… connecting shaft part 4 …… cylinder block 5 …… journal wall, 6 …… bearing hole 7 …… journal part, 8 …… lubricating oil holding groove 9 ...... Discharge path

Claims (2)

[Scope of utility model registration request] 1. Lubricating oil is supplied to a clearance between a journal portion and a bearing hole, and a lubricating oil holding groove is formed on an outer peripheral surface of the journal portion on the side opposite to the center of gravity, which has a center of gravity at a position eccentric from the center of rotation. The balancer shaft, wherein the center position in the circumferential direction of the lubricating oil holding groove is unevenly distributed in a counter-rotational direction with respect to a radial line passing through the center of gravity of the balancer shaft. 2. The lubricating oil holding groove is formed such that the width on the side opposite to the center of gravity is widest and is gradually narrowed toward the end in the circumferential direction. The balancer shaft described in the item.