JPS6123955Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an engine balancer device for eliminating unbalanced inertia forces, particularly unbalanced inertia couples, generated in the crank system of an engine.

Generally, a large unbalanced inertial force remains in the crank system of an engine, causing vibration and noise, and it is known to provide a balancer device to cancel out this unbalanced inertial force. (Unexamined Japanese Patent Publication 1973-
(Japanese Patent Publication No. 117806) However, such a balancer device has a problem in that it significantly increases the weight of the engine and reduces fuel efficiency and output.

In view of the above points, it is an object of the present invention to reduce the weight of the balancer and thereby provide a lightweight engine.

Although the first-order unbalanced inertia couple occurs in an odd-numbered serial cylinder engine, the present invention will be described for a three-cylinder engine. 1 and 2 are schematic diagrams that simply show the relationship between the crankshaft and the balancer.
As shown in the figure, crank pins 1, 2, and 3 corresponding to the first, second, and third three cylinders, respectively, are arranged at 120° intervals about the axis 4. In addition, in these cases, the first-order inertial force F is constant in magnitude (F=
F ₁ = F ₂ = F ₃ = Wcω ² rc/2g; ω = angular velocity of the crankshaft, rc = radius of rotation of the crank pin, Wc = reciprocating weight of the crank system of one cylinder), and at the same speed as the crankshaft. Configure it to rotate in the opposite direction. As shown in Figure 2, the inertia force F of the first and third cylinders is a first-order inertia couple M = 2LF centered on the second cylinder.
=COS30゜=√3Wcω ² rL/2g. The inertia couple Mc of the crank system can be canceled out by the couple M of the balancer 5, which is arranged parallel to the crankshaft and has weights 6 and 7. Furthermore, if the unbalanced weight of this balancer 5 is W, and its radius of rotation and the distance between its center of gravity and the center of the second cylinder are each r, then this couple M is expressed as M=Wω ² r/
It is indicated by g.

FIG. 3 shows an embodiment of the present invention, in which the balancer 5 includes weight parts 6, 7, bearing parts 8, 9, and a shaft part 10.
basically formed by a crankshaft (not shown)
Engine block 11 is placed parallel to
(or a suitable engine case), and the gear 1 is connected to the bearing part 8 on one end with a bolt 12 or the like.
3 is fixed, and the driving force from the crankshaft is transmitted to this gear 13 by another gear or belt 14, and the balancer 5 is rotated at a constant speed around the rotation center XX. two weight parts 6,
7 is disposed on the opposite side to the rotation center X-X, more specifically, in a symmetrical position with respect to the center O of the balancer 5, and of the bearing parts 8 and 9 at both ends, the bearing part 8 is located on the opposite side to the adjacent weight part 6. A semicircular groove-shaped space 8a is provided on the opposite side of the rotation center XX, and a space 9a is similarly provided in the bearing portion 9 on the other end side with respect to the weight portion 7. 15 is a thrust plate, and 16 is an end plate.

Here, as shown in the figure, the center of gravity of the weight parts 6 and 7 is 6a,
7a, weight W/2, radius of rotation r, center O
and further space 8a, 9.
The couple in the absence of a is M=2(Wω ² r/2g)=
Wω ² r. On the other hand, in the configuration in which the spaces 8a and 9a are provided, the bearing parts 8 and 9 that are far away from the center O also become unbalanced weight parts, so that W and r are respectively
Changes to W′, r′, ′.

At this time, it is clear that '>(r≈r).

Therefore, since the couple M is constant W′<W.

That is, the weight of the weight portions 6, 7 can be small, and combined with the weight reduction due to the voids 8a, 9a of the bearing portions 8, 9, the overall weight of the balancer 5 is greatly reduced.

FIG. 4 shows another embodiment of the present invention, in which a space 9a' is semicircular and extends over the entire width of the bearing part 9. This example has the advantage that the empty space 9a' can be used as a return passage for oil supplied from the oil supply passage 17, and machining of the return passage is not required.

Note that the hollow spaces in the bearing parts 8 and 9 are not limited to the shapes shown in the embodiments, and may be appropriately formed by casting or machining. Of course not.

As described above, the present invention is a balancer device that removes the unbalanced inertia couple that occurs in the crank system. By making simple changes, the weight of the balancer can be significantly reduced without impairing the function of the balancer.
As a result, the weight of the engine has been reduced, resulting in improved fuel efficiency and output, which is of extremely high practical value.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic diagrams for explaining the principle of the balancer according to the present invention, Figure 3 is an elevational view showing one embodiment of the invention, and Figure 4 is a main part showing another embodiment. FIG. 5... Balancer, 6, 7... Weight section, 8, 9...
...Bearing part, 8a, 9a, 9a'...Vacancy, 11...
Engine block, 13...Gear, X-X...Rotation center of the balancer.

Claims (1)

[Scope of utility model registration request] In a balancer device that is arranged parallel to the crankshaft and rotates to remove unbalanced inertia couples generated in the crank system, the balancer is connected between bearings at both ends and between these bearings and with respect to the center of rotation. What is claimed is: 1. A balancer device for an engine, characterized in that it is formed of weight portions located on opposite sides, and each of the bearing portions is provided with a void space located on the opposite side of the center of rotation from the adjacent weight portion.