JPH03168445A - Balancer device of engine - Google Patents

Abstract

PURPOSE:To contrive reduction of friction and weight in a bearing part and shortness, lightness of weight and highness of rigidity in a balancer shaft by arranging a set of main and subweight in positions with an almost 180 deg. angle shifted from each other on the balancer shaft staying between both bearing parts. CONSTITUTION:A main bearing part 20 and a subbearing part 21, serving as a set of bearing parts, and a main weight 22 and a subweight 23, serving as a set of weights, positioned between both bearing parts 20, 21, are provided on a balancer shaft 7A. The main weight 22 is arranged in a position in the vicinity of the main bearing part 20, while the subweight 23 is arranged in a position in the vicinity of the subbearing part 21 that is a position shifting by an almost 180 deg. angle from the main weight 22 with the balancer shaft 7A serving as the center, and reduction of a load on the subbearing part 21 is contrived. Here by forming the main bearing and subbearing parts 20, 21 on both end parts of the balancer shaft 7A, the main bearing part 20 is formed in a larger diameter than that of the subbearing part 21, while the main weight 22 is formed in larger weight than that of the subweight 23.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a balancer device for reducing secondary vibrations of a four-cylinder engine, etc., and particularly relates to an arrangement structure of a bearing section and a weight provided on a balancer shaft.

<Prior art> In a four-cylinder engine, etc., a balancer that rotates at twice the rotational speed of the crankshaft and has a rotation center approximately parallel to the crank axis is installed at one of the left and right positions with the crankshaft in between. one on the other, two spaced apart on the cylinder axis on the other
In order to reduce the secondary vibration of the engine, a balancer device is provided in which the balancers on both the left and right sides rotate in opposite directions.

Conventionally, as a structure of the balancer shaft of the so-called secondary balancer device as described above, there is a structure as shown in FIG. Publication No., Special Publication No. 55-3
6854, Japanese Patent Publication No. 56-7536, Japanese Patent Publication No. 57-44863, Japanese Patent Publication No. 54-2342, Japanese Patent Publication No. 57-17164, Japanese Patent Publication No. 60-438
(See Publication No. 4 and Japanese Patent Publication No. 61-23955, etc.). That is, in the figure, bearing portions 37 and 38 are formed at both ends of the balancer shaft 36, and a pair of weights 39.4 are formed on both sides of one bearing portion 37 of the balancer shaft 36, respectively.
0 is predominant.

<Problems to be Solved by the Invention> However, in the balancer shaft 36 of the conventional balancer device as described above, a pair of weights 39 and 40 are provided on both sides of one bearing portion, that is, the main bearing portion 37. Since the balancer shaft 36 is inserted and installed from the front side of the engine, the diameter of the main bearing part 37 has to be larger than the diameter of the weight 39, as can be seen from the figure. do not have.

As a result, not only the friction of the bearing part 37 increases, but also the diameter of the weight 39 is determined by the diameter of the bearing part 37 and cannot be made sufficiently large, so the W of the weight 39
The radius R of the center of gravity in R (radius of the center of gravity x weight) becomes smaller, and the weight W becomes heavier as a result in order to ensure the WR of the weight 39.

Furthermore, if the above-mentioned problem were solved by using an external weight type, the number of housing parts that cover the weight would increase, which would increase costs and reduce reliability, which is not desirable.

Therefore, in view of the above-mentioned conventional problems, the present invention aims to improve the arrangement structure of the bearing part and the weight in the balancer shaft, and achieves lower friction, lighter weight and smaller size, and a sufficient radius of the center of gravity of the weight. The purpose is to achieve the following.

<Means for Solving the Problem> For this reason, the engine balancer device of the present invention is provided with a pair of bearings on the balancer shaft and a pair of weights located between both bearings, and one weight is connected to the other. At the same time, the other weight is placed near the bearing and the other weight is connected to the other weight by approximately 18 cm with respect to the balancer shaft.
The structure is such that they are arranged at positions shifted by an angle of 0°.

<Operation> In such a structure, since both weights are arranged on the balancer shaft between both bearing parts, for example, the diameter of the main bearing part which is one of the bearing parts is made smaller than the diameter of the main weight which is one of the weights. This eliminates the need to increase the diameter of the main weight, which not only reduces friction in the main bearing, but also allows the diameter of the main weight to be adjusted independently of the diameter of the main bearing, making it possible to make the main weight sufficiently large. It is now possible to increase the radius of the center of gravity of the balancer, resulting in a reduction in weight, as well as eliminating the need to increase the length of the main weight in the width direction, making it possible to shorten the balancer axis. Contributes to lightweight and high rigidity.

Furthermore, since it is an external type and there is no need to solve the problems of the conventional type, there is no need for an increase in the number of housing parts, an increase in cost, or a decrease in reliability.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIGS. 2 and 3, the small end 3a of the connecting rod 3 is attached to a cylinder of an in-line four-cylinder engine. The large end 3b is connected to a crank pin 4 of a crankshaft (not shown).

The crank journal 5 of the crankshaft is supported by a bearing (not shown) formed in the engine.

A first balancer 7a is arranged on the left side in the figure, and a second balancer 7b is arranged on the right side of the left and right sides with the engine crankshaft in between. Both balancers 7a,
The balancer shafts 7A of each of the balancer shafts 7b each have a rotation center substantially parallel to the axial direction of the crankshaft, and are disposed at a predetermined distance in the axial direction of the cylinder l to form a pair. Both balancer shafts 7A rotate in opposite directions at twice the rotational speed of the crankshaft via chains, chain sprockets, etc. (not shown).

In Fig. 2, 9 is the oil van, 10 is the oil filter, 1l is the combustion chamber, 12a is the intake valve, 12b is the exhaust valve, 13 is the intake pipe, 14 is the exhaust pipe, 15 is the intake throttle, and l6 is the camshaft. , 17 is a fuel injection valve, and 18 is a spark plug.

Here, the balancer shafts 7A of the pair of balancers 7a and 7b are arranged as shown in FIG.

That is, in the figure, the balancer shaft 7A has a main bearing part 20, a sub bearing part 21, and both bearing parts 20.2 as a pair of bearing parts.
A main weight 22 as a pair of weights located between
and a sub-weight 23 are provided. Main weight 22
is arranged near the main bearing portion 20. Further, the sub-weight 23 is arranged at a position near the sub-bearing part 21 and angularly shifted from the main weight 22 by approximately 180 degrees with respect to the balancer shaft 7A, and is responsible for reducing the load on the sub-bearing part 21.

Here, the main bearing part 20 and the sub-bearing part 21 are the balancer shaft 7.
The main bearing part 20 is formed at both ends of A, and the main bearing part 20 has a larger diameter than the sub-bearing part 21. Further, the main weight 22 is designed to be heavier than the sub weight 23.

As shown in FIG. 3, the main bearing part 20 is supported by a bearing metal part 25 formed on the cylinder block 24, and the sub bearing part 21 is supported by a ball bearing 26 mounted on the cylinder block 24.

As shown in FIG. 3, the main bearing portion 20 is disposed approximately at the center in the longitudinal direction of the engine.

In the figure, 27 and 28 are thrust receiving parts provided on the balancer shaft 7A in the vicinity of the bearing parts 20 and 2l, respectively.

The WR (radius of the center of gravity x weight) of the main weight 22 and the WR (radius of the center of gravity x weight) of the sub weight 23 in the balancer shaft 7A having such a configuration are determined as follows.

The loads required for the main bearing portion 20 and the sub-bearing portion 2l of the balancer shaft 7A are expressed by the following equations.

That is, the main bearing part 20 has the following formula: F=2mrω'' A2 However, m: Reciprocating part weight r: Crank radius ω: Crank angular speed θ: Crank angle A2: 1/λ+1/4λ3+... [λ: l/r(ll : Connecting rod length) For the sub bearing portion 2I, f=0.

Then, the resultant force of the main weight 22 and the sub-weight 23 is expressed with reference to FIG. The resultant force F′ is F′=WRω”・(b/a+b)−Wrω”(
d/c + d).

Also, the resultant force f' of the two secondary bearings is f' = WRω" - (b/a+b)-wrω" (
d/c + d).

Therefore, if r' = r = o, then a + b = c + d, so wr of the sub weight 23 is wr = (a/c) x
It would be a good idea to make it WR.

Also, if F' = F, then WR(11" ・ (b/a+b)-Wrω"( d
/c+d)=2mrω” A. Therefore, wR (1/L)(b-(a-d/c))
=2mrA. is derived, and from this, W of main weight 22
R is WR=2mrAz − L/[b− (a
-d/c).

According to the balancer device equipped with the balancer shaft 7A having such a configuration, the main weight 22 is arranged near the main bearing part 20, and the sub weight 23 is arranged near the sub bearing part 21 with the main weight 22 centered on the balancer shaft 7A. As a result of arranging them at positions shifted by an angle of approximately 180 degrees, the following effects and
be effective.

That is, since both weights 22 and 23 are arranged on the balancer shaft 7A between both bearings 20 and 21, there is no need to make the diameter of the main bearing 20 larger than the diameter of the main weight 22, and the friction of the main bearing 20 is reduced. This can be reduced. In addition, since the diameter of the main weight 22 can be shaped independently of the diameter of the main bearing 20, it can be made sufficiently large, and the radius R of the center of gravity in WR (radius of center of gravity x weight) of the main weight 22 can be This makes it possible to secure the WR of the main weight 22 and reduce the heavy IW as a result, and there is no need to increase the length of the main weight 22 in the width direction. The balancer shaft 7A can be shortened, contributing to lighter weight and higher rigidity.

Furthermore, there is an advantage that no unbalanced force is applied to the auxiliary weight 23.

Furthermore, since there is no need to solve the problems of the conventional type with externally attached weights, there is no need for an increase in the number of housing parts, an increase in cost, or a decrease in reliability.

Next, other embodiments of the present invention are shown in FIGS. 5 to 12.

The one shown in FIG. 5 uses a rolling bearing 29 as a bearing that supports the main bearing portion 20, and can further reduce friction.

What is shown in Fig. 6 is the main weight 2 of the balancer shaft 7A.
2 and the sub-bearing part 21 is provided with a bent part 30 which is bent in a substantially U-shape and has a part whose axis is offset by a predetermined distance f4a, and this bent part 30 constitutes a sub-weight. be.

This structure has the advantage that the auxiliary weight part can be easily shaped and has excellent manufacturability.

In the case shown in FIG. 7, tungsten 31 is cast into the main weight 22 in a layered manner, and the WR of the main weight 22 described above is
By increasing the W of the main weight 22, the shape of the main weight 22 is reduced, and the dimension a in FIG.
It is possible to further reduce weight and size.

The main bearing portion 20 shown in FIG. 8 has a barrel shape, and can prevent uneven contact between the outer circumferential surface of the main bearing portion 20 and the inner circumferential surface of the bearing.

Furthermore, in the one shown in FIG. 9, an auxiliary third weight 32 is provided at the outer end portion of the main bearing portion 20 of the balancer shaft 7A. This has the effect of preventing uneven contact between the bearing and the inner peripheral surface of the bearing.

In this case, the WR of the main weight on the balancer axis (radius of the center of gravity x weight) and the WR of the secondary weight (radius of the center of gravity x weight it)
Referring to FIG. 10, the load F and resultant force F" required for the main bearing are F=F'=((b/L)WR+
(Lll/L)W. R(d/L)wr) ω”
=mrω"AzAlso, the load f and the resultant force f' required for the secondary bearing are f=f' = ((a/L)WR- (f/
L)W. It is sufficient to determine a value that satisfies Rt(c/L)wr)ω''=0.

In this case, since the number of parameters increases, it cannot be determined uniquely, so it must be determined based on layout constraints, etc.

In the one shown in FIG. 11, a sub-weight 35 is provided on a substantially cylindrical balancer shaft driving pulley 34 which is fastened to the outer end of the balancer shaft 7A on the sub-bearing side by a port 33. . In this case, the weight 35 portion may be formed integrally with the inner peripheral portion of the pulley 34.

This structure has the advantage that the secondary weight can be easily shaped and is easy to manufacture.

Furthermore, as another embodiment, the wr of the secondary weight is set to be slightly larger than that derived by the above-mentioned formula wr = (a/c)XWR to reduce deformation and displacement of the balancer shaft in the main bearing part. However, the structure of the above embodiment does not indicate any structural limitations of the present invention, and the present invention is essentially a balancer shaft having a pair of bearings located between a pair of bearings and both bearings. A pair of weights are provided, one of the weights is placed near one of the bearings, and
It is sufficient if the other weight is placed at a position near the other bearing part and angularly shifted from the other weight by approximately 180 degrees with respect to the balancer axis.

<Effects of the Invention> As explained above, according to the balancer device according to the present invention, a pair of weights are disposed between a pair of bearings on a balancer shaft, one weight is placed near one of the bearings, and the other The weight is placed near the other bearing at an angle of approximately 180" with respect to the balancer axis, reducing the friction of the bearing and increasing the radius of the weight's center of gravity. mitigation,
The balancer shaft can be made shorter, lighter, and more rigid.

Furthermore, it is highly useful in reducing costs and improving reliability.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a balancer shaft in an engine balancer device according to the present invention, in which (a) is a front view, (a) is a front view;
b) is a plan view, (C) is a side view, Fig. 2 is a longitudinal cross-sectional view of the engine to which the above halancer device is applied, Fig. 3 is a cross-sectional view of the cylinder block showing the attachment part of the balancer shaft, Fig. 4 is a schematic diagram of the relationship between the balancer shaft, the bearing section, and the weight, FIG. 5 is a front view showing another embodiment of the balancer shaft, and FIG. 6 is a diagram showing still another embodiment of the balancer shaft. ) is a front view, (b) is a plan view, (C) is a side view, FIG. 7 is a diagram showing still another embodiment of the balancer shaft, (a) is a front view, (
B) is a side view, FIG. 8 is a diagram showing still another embodiment of the balancer shaft, (a) is a front view, (b) is a plan view, (C) is a side view, and FIG. 9 is a balancer shaft. FIG. 10 is a diagram showing still another embodiment of the invention, in which (a) is a front view, (b) is a plan view, (C) is a side view, and FIG. 10 is a diagram showing the balancer shaft, bearing portion, and weight shown in FIG. Fig. 1l is a diagram showing still another embodiment of the balancer shaft, in which (a) is a front view, (b) is a plan view, (C) is a side view, and Fig. 12 is a diagram of a conventional balancer shaft. It is a figure which shows an example of a balancer shaft, (a) is a top view, (b) is a front view. 7A... Balancer shaft 20... Main bearing part 21...
・Sub bearing part 22...Main weight sub weight 3
0...Bending portion 23...

Claims (1)

[Claims] A balancer shaft is provided with a pair of bearings and a pair of weights located between both bearings, one weight is placed near one bearing, and the other weight is placed near the other bearing on the balancer shaft. An engine balancer device characterized in that the engine balancer device is disposed at a position offset from one weight by an angle of approximately 180° with respect to the center.