JPS6184434A - engine balancer device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a balancer device for suppressing engine vibration and noise, and improves its reliability.

<Prior Art> During engine operation, an unbalanced inertia force is generated in each cylinder due to the reciprocating movement of the piston. For example, in the case of a three-cylinder engine with crankshafts spaced 120' apart, the sum of the unbalanced inertia forces generated in each cylinder is approximately 9, but the inertia forces generated in the first and third cylinders are A part of the cylinder generates a moment centered on the second cylinder, which causes noise and noise. Therefore, a balancer device shown in FIG. 1 is used to cancel out such moments and suppress vibrations and noise. This balancer device is
As shown in the figure, both ends of the balancer shaft 3, on which two balance weights 1.2 are attached symmetrically and eccentrically with respect to the axis, are supported by bearings 4 and 5. A gear 6 is fitted to the right end, and this gear 6 meshes with a crankshaft (not shown).

Therefore, when the crankshaft rotates, this rotation is transmitted to the balancer shaft 3 via the gear 6, causing the balancer shaft 3 to rotate.

<Problems to be Solved by the Invention> Since the balance weights 1 and 2 are attached symmetrically and eccentrically to the balancer shaft 3, the centrifugal force F acting on the balance weights 1 and 2 causes the balancer shaft 3 to
A deflection occurs (the deflection curve is indicated by e in the figure).

As a result, the gear 6 attached to one end of the gear swings around, and if the tolerance limit is exceeded, the gear 6 disengages from the crankshaft. If a sprocket or the like is used in place of the gear 6 and connected to the crankshaft via a belt or chain, the allowable limit for whirling is larger than when using the gear 6, but if this limit is exceeded, the sprocket There was no change in the fact that Cheno and others would be removed. In order to suppress the whirling of such power transmission means such as gears and sprockets within permissible limits, the following two measures have been conventionally taken. One of them is
Although this increases the rigidity of the balancer shaft 3, it requires an increase in cross-sectional area, resulting in an increase in inertia and weight. Another method is bearing 4.504
This method places balance weights concentrated on the sides, but there are problems such as the structure of the block, processing, and assembly being difficult and often impracticable.

By the way, in the conventional balancer shaft 3, the balance weight l and the bearing 5 are attached at one end side (hereinafter referred to as the front side) where the power transmission means such as the gear 6 is attached.
Since the distance X between the balance weight 2 and the bearing 4 at the other end (hereinafter referred to as the rear side) is equal, the deflection angle of the points Rm and RB supported by the bearings 4 and 5 during rotation is 1a r jb were equal. In contrast, in the present invention, by setting That is.

<Means for Solving the Problems> The configuration of the present invention that achieves the above object includes a balancer shaft in which two balance weights are mounted symmetrically and eccentrically with respect to the axis, and both ends of the balancer shaft are attached. In an engine balancer device comprising supporting bearings and a power transmission means attached to one end of the balancer shaft to transmit power from the crankshaft, the balancer shaft is attached to one end of the balancer shaft to which the power transmission means is attached. The distance between the bearing and the balancer is smaller than the distance between the bearing and the balancer at the other end of the balancer shaft.

To easily explain the action, the balancer shaft will be considered as a simple beam supported at the point RA + Ra as shown in Fig. 3, and the centrifugal force F of the balance weight will be expressed as shall work. The deflection angle of 1ml for 8 people due to the centrifugal force F on the front side is calculated by the following formula (
1), and when expressed in a diagram, it becomes as shown in Fig. 4.

However, E is the longitudinal elastic modulus of 9, and I is the moment of inertia of the area.

Further, the deflection angle 1a2 of the 8 points due to the centrifugal force F on the rear side is expressed by the following formula (2).

Deflection angle at point RA due to centrifugal force F on the front and rear sides1. is i, 1 and 11□ as shown in equation (3) below.
When expressed in a diagram, it is shown in Figure 5.

is”t,, +fa2・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
(3) As shown by the broken line in Fig. 5, when xl and be. Therefore, in the present invention, Xb) x, ffp,
The deflection angle 11 is made small so as to be in the region below the broken line shown in FIG. However, Xb and xI
If the difference in I becomes too large, it will become 11<0, and deflection with an opposite phase will occur, so 1. It is desirable to limit the range to >0. Therefore, it is preferable to adjust X@ and Xb so that the region C shown by diagonal lines in FIG. 5 is obtained.

In addition, in order to satisfy 11≧0, x, , x, are expressed as the following formula (4
) must be satisfied.

(1” (i xa)”) (lxa) <l” Xb2
) Distance from 4xb
It can be the same as the conventional one shown in FIG. 1, except that it is smaller than the one shown in FIG.

For example, x, /l = 0.15, xb// =
If 0.20, then X-/l = xb/l = 0.
15, the deflection angle 11 at point RA can be reduced to about half (see FIG. 5). Xb/l t
” If the pitching moment is changed from 0.15 to 0.20, the pitching moment will decrease, so to compensate for this, the balance weights 1 and 2 must be increased by 1.07 times, and for this reason the deflection angle 11 becomes 7. 6%, but even if this is taken into account, the above-mentioned effect is still large. However, while the deflection angle l at point R^ is about 1/2, the deflection angle 11 at point RB is about 372 times larger, but the rear Since no power transmission means such as the gear 6 is attached to the side, it is sufficient to pay attention only to the influence of the deflection angle on the bearing and keep it within the permissible range.This permissible range is larger than that on the front side.

In the embodiment described above, x,/l=0.15·xb/l=
Although it is set as 0.20, it is not limited to this, and it should be within the shaded area C shown in Fig. 5! , , XI, should be adjusted. For example, if x, /l = 0.15, then 0.25≧xb
If /l > 0.15 and xa/l = 0.20, it may be adjusted so that it falls within the range of 0.324zb/l≧0.20.

<Effects of the Invention> As explained above in detail, in the engine balancer device according to the present invention, the distance between the balance weight and the bearing on the front side is made smaller than the distance between the balance weight and the bearing on the rear side. Therefore, the deflection angle on the front side becomes small, and the deflection of the power transmission means is reduced. Therefore, the crankshaft and the power transmission means do not become disengaged or disengaged, improving reliability. Although the illustrated example shows a balancer device for a three-cylinder engine, the present invention is not limited to this.
The invention can also be applied to balancer devices for engines with four or more cylinders.

[Brief explanation of the drawing]

Figure 1 is a front view of the engine balancer device, Figure 2 is a sectional view taken along line A-A in Figure 1, Figure 3 is an explanatory diagram of a simple beam considered as a balancer shaft, and Figure 4 is a deflection angle of 1 ml.
A graph showing the relationship between
1 is a graph showing the relationship between X and /l. In the drawings, 1.2 is a balance way, 3 is a balancer shaft, 4.5 is a bearing, 6 is a gear, 1% lib is a deflection angle, and F is a centrifugal force.

Claims (1)

[Claims] A balancer shaft has two balance weights mounted symmetrically and eccentrically with respect to the axis, a bearing that supports each end of this balancer shaft, and a bearing that is attached to one end of this balancer shaft to transmit power from the crankshaft. In an engine balancer device, the distance between the bearing at one end of the balancer shaft to which the power transmission means is attached and the balancer is the same as the distance between the bearing at the other end of the balancer shaft and the balancer. An engine balancer device characterized by being small compared to the distance between the engine and the engine.