JPS5837347A - Balancer for 3-cylinder engine - Google Patents

Abstract

PURPOSE:To contrive the weight reduction and miniaturization of a balancer by using one of balancer sets provided to a balancer shaft corresponding to two bearings on the first and third cylinder sides of a crankshaft as a bearing concurrently. CONSTITUTION:In the first cylinder of a crankshaft 1, counter weights 6a'-1 and 6a'-2 are provided at two places corresponding to both crank arms 2a-1 and 2a-2, and in the third cylinder, counter weights 6c'-1 and 6c'-2 are provided at two places corresponding to crank arms 2c-1 and 2c-2. Also, in a balancer shaft 7, balancers 8c'-1 and 8c'-2 are provided at places corresponding to bearings 9c and 9d on the first cylinder side of the crankshaft 1, and balancers 8c'-1 and 8c'-2 are provided at places corresponding to bearings 9c and 9d on the third cylinder side. Of these, the balancers 8a'-1 and 8c'<-2> on both outsides serve as a bearing 23 concurrently.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a three-cylinder automobile engine with a counterweight on the crankshaft itself, and a balancer shaft that rotates in the opposite direction at the same speed as the crankshaft. The present invention also relates to a balancer device that balances the first-order inertia force due to the rotating mass and the first-order inertia couple around the X-axis, and also balances the first-order inertia couple in the longitudinal direction of the crankshaft.

In each cylinder, there is an inertia force due to the reciprocating mass and a rotating mass.The inertia force due to the rotating mass can be balanced out by installing a counterweight on the opposite side of the crank arm.The inertia force due to the reciprocating mass is due to the rotating mass. The balance can be half balanced at the same position as the crankshaft, and the remaining part can be balanced by a balancer shaft that rotates in the opposite direction at the same speed as the crankshaft. By the way, in the case of a three-cylinder engine, even though the inertia forces of each cylinder are balanced as described above and the inertia couple around the X axis is also balanced, an inertia couple occurs in the longitudinal direction, and it is necessary to balance this inertia couple. In order to eliminate this problem, conventionally, for example, the counterweight of the rank axis has a specific separation structure as in Japanese Patent Application Laid-Open No. 55-6035, or
As disclosed in Japanese Patent No. 4-2333, there is a system in which an inertia couple having the same magnitude and opposite direction as the inertia couple of the crankshaft system is generated on the balancer shaft to cancel it out.

The above is related to the balance of the inertia no.j and the inertia couple, which are generally referred to in a three-cylinder engine.

In other words, in an engine with an odd number of cylinders, such as a three-cylinder engine, the intermediate second
Since the inertial forces of the first and third cylinders act symmetrically on both sides of the cylinder, the inertia couple in the longitudinal direction of the crankshaft must be taken into account, and this It also has a large effect on vibration. On the other hand, the longitudinal couple of whirling due to this inertial force can be balanced by a balancer on the balancer shaft, but in this case, even if the couple is constant, the mass can be changed according to the distance between the balancers, so the balancer By specifying the mounting position of the balancer shaft, it becomes very advantageous in terms of the structure of the balancer shaft itself, the degree of freedom in design, the arrangement relative to the crankshaft, etc.

In view of these circumstances, the present invention achieves balance against inertial force and inertial couple by using a counterweight on the crankshaft and a balancer on the balancer shaft, and also brings the balancer shaft closer to the crankshaft side, making it lighter and smaller. An object of the present invention is to provide a balancer device for a three-cylinder engine that is advantageous for bearing support and prevents inconveniences when a balancer shaft is immersed in oil.

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings. First, to explain the balance system per cylinder in Fig. 1, in the figure, numeral 1 is the crankshaft, 2 is the crank arm arranged at equal intervals of 1206, 3 is the crank bin, 4 is the connecting rod, and 5 is the piston. A counterweight 6 is provided on the extension line of the crank arm 2 on the side opposite to the crank bin 3 to half balance the entire inertial force due to the rotating mass and the inertial force due to the reciprocating mass. Also,
One balancer shaft 1 is provided that rotates in the opposite direction at the same speed as the crankshaft 1, and a balancer 8 is provided that half-balances the remaining part of the inertial force due to the reciprocating mass. As shown in the figure, when the crank arm 2 is rotated clockwise by θ from the top of the Z-axis, the balancer 8 of the balancer shaft 1 is positioned counterclockwise by the same angle θ from the bottom of the Z-axis. Here, if the inertia of the reciprocating part is -p, and to make the explanation easier to understand, the equivalent inertial mass of the crank bin 3 of the rotating part is mc, then the mass of the counterweight 6 on the cranking shaft side is the reciprocating quality [1i+p] For this, it is only necessary to half-balance Wap/2, and for 1 mc of rotational quality, it rotates in the same direction as crankshaft 1, so it is possible to balance all of it, resulting in Kasumi C, and the total is (ip/2). 2)+l! 'C. Further, the mass of the balancer 8 on the balancer shaft side becomes -p/2, which is the remainder of the above-mentioned reciprocating mass.

By doing this, the Z of the reciprocating part and the rotating part.

The inertial forces in the Y direction will all be balanced! Therefore 3
In a cylinder engine, if a counterweight 6 and a balancer 8 of each mass are attached to the positions corresponding to each cylinder, then the total mass of the counterweights on the crankshaft side is 3 ((mp/2) + 1ac). The total mass of the balancer on the shaft side is (3/2) sp.

Next, the balance due to the mass of the reciprocating part in a three-cylinder engine will be explained with reference to Figure 2.
or 3rd cylinder is indicated by suffix a or c,
Also, the second cylinder is at top dead center, and the first cylinder is at the top dead center.
40'' rotation position, and the third cylinder is at 120' rotation position.

Therefore, when the cylinder moves by θ from this state, the excitation force Fpl of the first cylinder, the excitation force Fp2 of the second cylinder, and the excitation force Fp3 of the third cylinder are as follows.

Fp1=spr O2cos (θ+240)Fp2
=Ipr O2CO8θ Fp3-mprω2cos (θ+120) Then, the total inertial force is balanced by F p1+ F p2+ F p3=0.

In addition, in order to give the inertia couple in the longitudinal direction of the crankshaft a -membrane property, it is viewed from a point P that is a distance S apart from the first cylinder, and the pitch of each cylinder is [, then Fl)1・S+F' p2(S+L)+Fp3(S+21
> is indicated.

That is, 1:pl・S+Fp2(S+L)+Fp3(S+21)
= -JTmpr ω21 sin θ---(1), and a longitudinal couple around the Y axis is generated due to the reciprocating mass which is a weight in two directions.

To explain the balance due to the quality of the counterweights 6a, 6b, and 6c that are half-balanced for each cylinder in FIG. 3, the case where the second cylinder is at top dead center is shown as in FIG. counterweight 6
a, 6b, 6c are crank arms 2a, 2b.

It is located at a position 180° in phase with respect to 2C. Therefore, in the two directions when moving by θ from this state, the force due to each counterweight mass 1: recl, F rec2,
Frec3 becomes as follows.

Frecl= (mp/2) r ω2 cos
(θ+240 + 180) Frec2= (mp/
2) r oo2 cos (θ+180)F r
ec3= (mp/2) r ω2 cos (
θ+120 +180) Therefore, the inertia force in the Z direction becomes Frecl+ Frec2+ Frec3-Q and is balanced.

On the other hand, if the inertia couple in the longitudinal direction due to such a force in the Z direction is found in the same manner as above, it becomes F recl ・S + F rec2 (S + L
) + F rec3 (S +21) - (FJ/2) wpr oo2 L si
n θ , , −(2a), and similarly Y
produces a longitudinal couple about the axis.

In addition, the counterweights 6a, 6b, and 6c have a component not only in two directions but also in the Y direction, and the inertia force is balanced in the Y direction, and the inertia couple in the longitudinal direction due to the force in the Y direction is as follows. .

-(IN/2) ipr oo2 Laos
θ, −(2b), that is, a longitudinal couple around two axes is generated due to the force in the Y direction.

・Crankshaft side counterweight 6a or 0 to 60
The inertia couple in one direction generated by this occurs around the seven wheels in the Z direction and around the Z wheel in the Y direction, and the combination of both is as follows.

(Jj/2) apr ω2 L sin θ−
(Ji/2) mpr×ω21−cos θ = (Jj/2) mprω2 L (s
in θ-cos θ) ・ ・ ・ (3) By the way, in addition to providing the above-mentioned crankshaft side counterweight for each cylinder, it is also separately set in the 1st and 3rd cylinders on both sides except for the 2nd cylinder in the center. It is also possible to provide the same, and this case will be explained with reference to FIG. To state the results without explaining the intermediate steps, the counterweights 6 and 6σ of the first and third cylinders are (T/2') (l1
M2), the counterweight U of the first cylinder is
This is a position further 30' phase advanced from the position 180° phase advanced from crank arm 2a, and the third cylinder counterweight 6σ is 30° phase behind the position 180° phase advanced from crank arm 2C. The location is numbered. In other words, on both counterweight sides, 6σ is relative to crankshaft 1.
This position is 180° in the opposite direction and perpendicular to the central crank arm 2b.

In this case, 2 when moving by θ from the state shown in the figure.
Force F recl' due to each counterweight mass in the direction
, l” rec3' is 1'l:rec1' −
(Jj/2) (mp/2) r (i)2xc
os(θ+240 +180 +30)):rec3'
= (j'j/2) (II)/2) r (t
)2xcos(θ+120 +180-30), and the Z-direction inertial force becomes F rec1' + F rec3' -0, which is naturally balanced.

Next, the longitudinal inertia couple due to this force in the Z direction is Frecl' ・S+Frec, 3' (S+21
)−<E/2) ipr ω2 L sin θ, which agrees with equation (2a).

The inertia forces are balanced in the Y direction as well, and the longitudinal inertia couple due to the force in the Y direction matches Equation 2b).

For this reason, three counterweights on the crankshaft side are provided for each cylinder, or one counterweight is provided for each cylinder. It is understood that even if two cylinders are provided in the third cylinder, the inertia forces are balanced and the inertia couple in the longitudinal direction becomes the same.

Above, we have explained the balance of inertia force due to the reciprocating mass and counterweight on the crankshaft, the longitudinal inertia coupling horn, that is, the whirling.
The longitudinal couple in the equation remains, and when combined, −Jjmpr ω2 L sinθ+(ffi/2 >
apr (Z)2XL(sinθ−COSθ) = −(IN/2) mproo2L (sin
θ+cosθ) (4) Therefore, how to balance such longitudinal eccentric force on the balancer shaft side will be explained with reference to FIG. first,
The balancer shaft 1 also has a balancer 8a corresponding to each cylinder.
, 8b, and 8c, the mass of each balancer 8a to 8G is mp/2 relative to the reciprocating mass on the crankshaft side. Further, as shown in the figure, when the second cylinder is at the top dead center, the balancer 8b corresponding to the second cylinder is at the opposite position on the bottom dead center side, and the balancer 8b corresponding to the first cylinder is at the opposite position.
a is further 180 degrees from the position where the phase has advanced 240 degrees counterclockwise.
At a position shifted by 180 degrees, the balancer 8C corresponding to the third cylinder is located at a position further 180 degrees in phase in a counterclockwise direction of 120''.

Therefore, the force F in 7 directions when moving by θ from this state
recl, F rec2. Frec3 is Fre
c1= (ip/2) r cc>2 cos (
θ+240 +180 )FreC2= (mp/2
) r ω2cos (θ+180)F rec3−
(mp/2) roo2cos (θ+120
+180>, the inertial forces in two directions are balanced, and the longitudinal couple around the Y axis due to this Z direction force is (j'N/2>+mprω2Lsinθ−−−(2a'
) Also, in the Y direction, the polarity becomes negative because it rotates in the opposite direction to the crankshaft, but the inertial force is balanced in the same way, and the longitudinal couple around the two wheels due to this Y direction force is <HI3) mp
r ω2 L cos θ, --(2b') Therefore, the inertia couple in the longitudinal direction generated by the balancers 8a to 8C on the balancer axis side is also generated around the Y axis due to the Z direction and 2 due to the Y direction.
It occurs around the ring, and the composite is the above (2a')
The equation and (2b') give the following equation.

(IN/2) a+pr oo2 L (sinθ+
cos θ)...(4') Incidentally, the balancer on the balancer shaft side can also be separated and assembled in the same way as the crankshaft side shown in FIG. The mass of balancer d and balancer 8σ equivalent to the third cylinder is ip/
2 multiplied by 5/2, the cylinder equivalent to the first cylinder is positioned further 30 degrees in phase, and the cylinder corresponding to the third cylinder is positioned 30 inches later in phase. The result is the same as in Figure 5, and it can be replaced with that.

As mentioned above, the balance of inertia force by the balancer on the balancer shaft side,
and the inertia couple in the longitudinal direction, and the result is equation (4'). Therefore, when this equation (4',) is combined with the previous equation (4), it becomes zero, and from this, the longitudinal inertia coupling due to the reciprocating mass generated on the crankshaft side and the mass of the counterweight that half-balances it. The forces will be balanced by the balancer on the balancer shaft side.

Next, we will explain the balance of the mass of the rotating parts of a three-cylinder engine.The configuration is the same as that shown in Fig. 2, and θ
The force acting on the 1st to 3rd cylinders at the position where they have moved, Fc
1. Fc2. Fe2 becomes as follows.

1”cl-marω2 cos (θ+240)Fe
2-44Or (c)2008θ Fc3= gmcrω2 cos (θ+120) As a result, the longitudinal couple around the Y-axis due to the rotating mass is -Jaa
cr ω2 Lsinθ --- (5a) The longitudinal couple around the two axes is the old -C "ω2LOO8θ ・φ ・ (5b)
Similarly, it occurs around the Y-axis in seven directions and around the Z-axis in the Y direction, and when combined, it becomes as follows.

-mmcr oo2 L (sinθ-cosθ) -
--(6) Next, this rotating mass is divided into 1:1 for each cylinder.
To explain the balance by the mass of the counterweights 6a to 6C, it is the same as the configuration shown in FIG. 3, and the force due to the mass of each counterweight, F ro
tl, F rot2. Frot3 is as follows.

Frot1=lOr (c)2 cos (θ+24
0 +180) Frot2-111cr O2CO
S (θ+180)FrOt3=llCrO2
CO8(θ+120 +180 >This makes 2
The longitudinal couple around the Y axis due to the direction is H@cr (7)2
1 sin θ ---(7a) The longitudinal couple around the two axes in the Y direction is -Iiscr cc+21-cos θ ---(7b
), and the combination of the two results in the following swing.

5mcr O21 (sin θ − COS θ
) --(8) By the way, also in the case of such a rotating mass, as shown in Figure 4, multiply the mass IIG by (10,000/2),
By advancing or retarding the 30' phase, it is possible to separate and concentrate the counterweights on the first and third cylinders.

Thus, regarding the rotating mass, the combined whirling longitudinal couple around the Y- and Z-axes in equation (6) becomes zero by combining with the similar longitudinal couple in equation (8) due to the counterweight, and the two will be balanced.

The present invention is based on such a technical idea, and a specific embodiment thereof will be explained with reference to FIG. 7. In the crankshaft 1, as shown in FIG. The cylinder is equipped with a counterweight, and in order to increase the degree of freedom in attaching the weight, the first cylinder has counterweights m- at two locations corresponding to both crank arms 2a-t and 2a-2. Similarly, in the third cylinder, counterweights 6σ-mm and 6σ-2 are placed at two locations corresponding to the crank arms 2cm1 and 2cm2.
is the provision. In addition, in the balancer shaft 1, based on the technical idea shown in Fig. 6, the first and third cylinders, excluding the part corresponding to the second cylinder in the center, are
On the cylinder side, two further crankshaft bearings 9a and 9
Focusing on the points b, 9c and 9d, two balancers M-1 and Maki-2, Bc! are placed in the corresponding two locations. -1
, Fx! -2 is provided in two sets.

Two counterweight sides of crankshaft 1 - 1°6f
The mass ratio of -2 does not necessarily have to be equal, and can be arbitrarily determined by simply changing the combined center of gravity position, and the same holds true for the other two counterweights 6σ-166c'-a. In addition, when the mass of the reciprocating part and rotating part of the engine is separated and concentrated on the first and third cylinder sides, as is clear from the above explanation, the combined mass of each cylinder side is ((11ip/2 > +mc) (Old/2), it is sufficient to adjust the phase by 30 degrees, so if the pitch of each cylinder is L as in Fig. 2, for the longitudinal couple, ((mp/2) +tc) <5/ 2) 21
- (IN/2)X IIIFIL + 5 s+c
It is sufficient to generate l.

Therefore, the synthetic material and quantity of counterweights 6a'-1 and ea'-2 are Mca', and the counterweights are 1,6
If the combined mass of σ-2 is lyl cc', then the inertial force on the crankshaft 1 is also pJj ca' considering the balance.
= M QC' must be maintained.

Then, the combined center of gravity position of the counterweight 6cr-i+6f-a is L+X, and the counterweight 6σ-1, 6σ-
If the combined center of gravity of 2 is L+y, then Mca' = Mcc' = ((Jj/2)
s+pL+JjscL) /(2L+X+V
)...(9) becomes.

Here, x = y = 0, that is, the counterweight side -1
If the combined center of gravity positions of ゜6za-2, 6C'-x, and 6d-2 match the pitch of each cylinder, the quality IMca'
, MCC' is (Jj/4 > mp+ (IN/
2) It becomes sc. Also, X.

Since y is arbitrarily determined, the masses Mca' and Mca' can be reduced as the value of y is increased and the center of gravity is spaced apart.

Next, on the balancer shaft 1, the balancer gear and the P2-1 and D-2 are arranged in the same way as the above-mentioned counterweight, and the mass ratio of each pair is arbitrary. Balancer art, the heavier Ki-2 becomes, the more advantageous it becomes. Furthermore, as is clear from the above explanation, if the mass is only the mass of the reciprocating part of the engine and is separated and concentrated on the first and third cylinder sides, then the mass of each cylinder is (-
p/2 ) <ffi/2 ), it is sufficient to adjust the phase by 30″, and (+p/2 ) (Jj/2 ) 21− (
It is sufficient to generate a longitudinal couple of j'j/2)@pL.

Therefore, the combined mass of balancers Maki-1 and M-2 is M ba'
, the combined mass of balancers 81'-1 and 8σ-2 is M b
c', M ba' and -M bc' are held in consideration of the balance of inertial forces on the balancer axis, and the balancer 67-1. m-
The center of gravity position of 2 is 1 + x', balancer 8σ-1,8
If the center of gravity of σ-2 is L +'V', then Mba'(=Mbc')x (1+ x' +l+
yl) = (j'N/2)ipL, and as a result, Mba' - Mbc' = ((J"j/2) + np
L)/(2L+x'+y')...■).

From this, in the crankshaft 1, the relationship between the counterweights e, r-i, e, r-2 on the first cylinder side and the counterweights 6σ-1, 6σ-2 on the third cylinder side with the composite center of gravity position is as follows. Both masses satisfy equation (9), and the positions of the counterweights ea-, 6a-2 are opposite to the crank pin and the phase is advanced by 30 degrees, and the counterweights 6σ-, 6a-2 are
Position -2 is on the opposite side of the crank pin and delays the phase by 30 degrees.

In addition, in the balancer shaft 7, the balancer ski-1 and M-a are connected to the counterweights 6-1 and 5r-2 on the first cylinder side.
The balancer W! is placed on the corresponding portions of the crankshaft bearings 9a and 9b on both sides of the crankshaft bearings 9a and 9b. -x.

Do-2 is the above counterweight 6σ on the third cylinder side.
-1, 6['-2 are placed on the corresponding parts of bearings 9c and 9d on both sides, and their masses are both (support) in relation to the composite center of gravity position)
Make it satisfy the formula. When the second cylinder is at the top dead center, the rotational center of gravity of the balancers M-4 and M-2 is at the counterweight 6['-1. Eiσ-2 is made to match, and the rotational center of gravity of the balancer 8c'-1 and the balancer-2 is made to match the counterweights 6al'-1 and 6a-2, so that the reciprocation of the three-cylinder engine The inertial force and couple due to the mass of the part and the rotating part are balanced.

Furthermore, a total of 4 balancers are provided, 2 each distributed over 2 phases. In am-2, Ki-1, and Shi-2, both outer balancers M-1 and 8c'-2 are configured to serve as bearings in order to support the balancer shaft 1 well. To explain in detail with reference to FIG. 8, first, the balancer gear 1 is built into a shaft tube 20 having a full circumference shape centered around the balancer shaft 7, and this shaft tube 20 is fitted into a shaft support 22 common to the bearing 9a through a metal 21. be assembled together. Balancer Pea-2
are constructed in exactly the same manner and are assembled to the common shaft support 24 with the bearing 9d, and as a result, the balancer shaft 7 is connected to the bearings 9b and 9c for the two inner balancers 8=ra, 8σ-1.
A considerable portion is left in a free state, and the balancer s on both sides
Bearing 23 with the above configuration in at -1, 8C'-2
As a result, the image holder is rotatably supported, and there is no need to provide any other bearings.

And all balancers M −1, M −2, 8σ−
1°8σ-2 is the counterweight IJ of crankshaft 1
-1゜61-2.6 ('-1, 6σ-2) is placed in the corresponding part of the bearing and does not interfere with the counterweight. It is possible to arrange the counterweight close to the crankshaft 1 side in relation to only the counterweight without considering its existence.

(The vibration is extremely low because of the balanced structure.)

In the balancer shaft 7, the balancer shafts 1, aa-2, aC'-1,
Since A and 2 are set [J, space can be used effectively, / \ lancer installation is advantageous, and balancer shaft 1
can be brought closer to the crankshaft 1 side, contributing to miniaturization.

In addition, since both outer balancers M-1 and M-2 have a built-in bearing structure and also serve as bearings for the balancer shaft 7, the bending moment generated on the balancer shaft 7 is reduced.
Providing the bearing of the balancer shaft 7 in the bearing-equivalent parts of the crankshaft bearings 9a, 96, etc. is a highly rigid part of the engine, and can prevent problems caused by elastic vibration of the engine due to repeated loads. Furthermore, some balancers M-1 and 8c may be partially submerged in oil due to the mounting position of the engine.
! In the case of -2, since it is housed in the entire circumferential shaft tube 20, the increase in resistance due to oil agitation, oil spray, etc. can be reduced by half compared to the case where the entire shaft is exposed.

In this case, the two inner balancers B1-2 and 5t-4 can also be provided with shaft tubes, which further enhances the above-mentioned effect.

A specific example of the balancer shaft installation shown in FIG. 9 will be explained. When one engine is assembled under the loading platform in the R-R method as shown in the figure, the engine body 10 is attached to the loading platform 16.
The air cleaner 11, the carburetor 12, the intake system of the suction pipe 13, the Tala compressor 14, the ACG 15, etc. are arranged on the engine main body 10 in such a position. . Therefore, the upper part of the engine body 10 is limited by the various auxiliary equipment mentioned above, so if the balancer shaft 1 is installed downward as shown in the figure,
The balancer shaft 7 is located below the crankshaft 1 and partially lies in the air, and in such a case, the effects of the present invention described above are exhibited.

[Brief explanation of the drawing]

1 to 6 are explanatory diagrams for explaining the present invention in detail,
FIG. 7 is a schematic diagram showing an embodiment of a balancer device for a three-cylinder engine according to the present invention, FIG. 8 is a sectional view showing a specific example of the main parts, and FIG. FIG. 3 is a side view showing a specific example. 1... Crankshaft, 2.2a, 2b, 2c, 2
a-1, 2a-2. 2C-z, 2cm2...crank arm, 6.6f-
1, 6E2 + "1. 6d-2... Counterweight, 1... Balancer axis, 8°G 1.M-2, 8σ-1, 8-2... Balancer, 20...・Axis tube, 21...Metal, 22...
Axial support, 23...bearing. Patent Applicant Fuji Heavy Industries Co., Ltd. Agent Patent Attorney Nobu Kobashi Ukiyo Patent Attorney Susumu Murai Figure 4 2 2a-22C-2 2 Figure 8

Claims (1)

[Claims] A predetermined mass is placed at a position perpendicular to the crank arm of the second cylinder on the opposite side of the crank pin of the crank arm of the first and third cylinders on the crankshaft in which the crank arms are sequentially arranged at equal intervals of 120 degrees. A counterweight is installed,
Rotating in the opposite direction at the same speed with respect to the above crankshaft 1
A main balancer shaft is provided, and on the balancer shaft, two bearings corresponding to the first cylinder side of the crankshaft and two bearings corresponding to the third cylinder side are provided.
Two sets of two balancers are provided for each bearing equivalent part, and the balancer for each phase is oriented to face the counterweight when the second cylinder is at top dead center, and the synthetic material is placed at each center of gravity. A balancer device for a three-cylinder engine, characterized in that a corresponding predetermined balancer is used, and one of the balancers in each set is used also as a bearing.