JPS5839851A - Balancer for three-cylinder engine - Google Patents

Abstract

PURPOSE:To contrive making a balancer into light-weight and compact size in such a way that balancers which are independent are installed on the parts corresponding to bearings for the first and third cylinders on a balancer shaft which revolves in the inverse direction to a crankshaft, and balancers which are divided into two parts are installed on the part corresponding to the bearings for the second cylinder, and then both of the balancer are made serve also as bearings. CONSTITUTION:Crank arms of a crankshaft 1 for the first and third cylinders are provided with the counter-weights 6a-1, 6a-2: 6c-1, 6c-2 and 6a'-1, 6a'-2; 6c'-1, 6c'-2 to the mass at the reciprocating parts and revolving parts of the engine. Besides, a crank arm for the second cylinder is provided with the counter-weights 6b-1, 6b-2 to only the mass of the reciprocating parts. Further, a balancer shaft 7 is installed for revolving in the inverse direction at the same speed as the crankshaft 1 which has been mentioned the above, balancers 8a, 8c are installed in the parts corresponding to bearings 9a, 9d of the first and third cylinders, and balancers 8b-1, 8b-2 which are divided into two parts are supported in a full-circumferential shape of shaft, and they are also used as bearings 23.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an automatic heavy-duty 3-car engine that is equipped with a counterweight on the crankshaft itself, and a balancer shaft that rotates at the same speed and in the opposite direction to the crankshaft. The balancer device balances the primary inertial force due to the reciprocating and rotating mass and the primary inertial couple around x@, and also balances the primary inertial couple in the longitudinal direction of the crankshaft. It is something.

In each cylinder, there is an inertia force due to the reciprocating mass and the 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, and the inertia force due to the reciprocating mass is due to the rotating mass. It is possible to half-balance in the same position as the case, and balance the remaining part with a balancer shaft that rotates in the opposite direction at the same speed as the crankshaft. By the way, in the case of a 3-kilo engine, the inertia forces of each cylinder are balanced as described above, and at the same time, even though the inertia couple around the X axis is also balanced, an inertia couple in the longitudinal direction occurs, and this inertia couple is In order to eliminate the balance, the counterweight of the crankshaft has been made to have a specific separation structure, as in the case of Japanese Patent Application Laid-open No. 55-6035, or Japanese Patent Publication No. 54
As disclosed in Japanese Patent No. 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 inertia force and inertia couple, which is generally said to be the case in a three-cylinder engine. In other words, in an engine with an odd number of cylinders, such as a three-cylinder engine, the inertial forces of the first and third cylinders act symmetrically on both sides of the second cylinder, which is located in the middle. The inertial couple must be taken into account, and this has a large effect on engine vibration. On the other hand, the eldest couple of swinging due to this inertial force can be balanced by the 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. To provide a balancer mounting for a three-cylinder engine which 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 sequentially arranged at equal intervals of 120°, 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 for half-balancing the entire inertial force due to the rotating mass and the inertial force due to the reciprocating mass. Further, one balancer shaft 1 is provided which rotates in the opposite direction at the same speed as the crankshaft 1, and a balancer 8 is provided which 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 positioned clockwise by θ from the bottom of the two wheels, the balancer 8 of the balancer shaft 7 is positioned counterclockwise by the same amount θ from the bottom of the two wheels. Here, the inertial mass of the reciprocating part is 19%. To make the explanation easier to understand, if the equivalent inertial mass of the rotating part of the crank bin 3 is -C,
The mass of the counterweight 6 on the crankshaft side is the reciprocating mass -
For p, it is sufficient to half balance it, so -p/2
, since the rotating mass -C rotates in the same direction as the crankshaft 1, all of it can be balanced and become -C, and the total becomes (Peng p/2) 10-C. Further, the balance of the balancer 8 on the balancer shaft side is the remainder of the above-mentioned reciprocating mass and becomes -p/2.

By doing this, the inertial forces of the reciprocating portion and the rotating portion in the 2°Y direction are balanced. Therefore, in a three-cylinder engine, if a counterweight 6 and a balancer 8 of the above-mentioned masses are attached to positions corresponding to each cylinder, then the total mass of the counterweights on the crankshaft side is 3.
((1M2)10-C), the total mass of the balancer on the balancer shaft side is (3/2)-p.

5- Next, the balance of 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 0,
Also, the second cylinder is at top dead center, and the first cylinder is at the top dead center.
The cylinder is rotated 40' and the third cylinder is rotated 120°.

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.

Fpl=+epr ω2 cos (θ+240)F
p2-spr ω2 cos θ Fp3-mpr ω2cos (θ + 120) Then, the total inertial force is balanced by F p1+ F p2+ F p3-0.

In addition, in order to have a negative membrane property, the inertia couple in the longitudinal direction of the crankshaft is viewed from a point P that is a distance S apart from the first cylinder, and if the pitch of each cylinder is L, then Fpl-8 + Fp2 (S + L) +Fp3 (S+2 L)
It is indicated by 6-1.

That is, Fpl・S+Fp2(S+L)+Fp3(S+21)−
-j'N5pr ω2 Lsln θ---(1
), and the reciprocating mass, which is a load in two directions, causes a couple of arms around the Y-axis.

To explain the balance by mass 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. 2; 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 F recL F rec2,
Frec3 becomes as follows.

FreclL (-p/2) r ω2
cos (θ +240 +180) F re
c2- (M2) r ω2 cos (Iθ
+180) Frec3- (sD/2) r ω2
cos (θ+, 120 +180) Therefore, 2
The inertial force of direction 14 is F recl + l” rec2+ Frec3-0
On the other hand, if the inertia couple in the longitudinal direction due to such a force in the Z direction is obtained in the same manner as above, F real −S + F rec2 (S + L
) + F rec3 (S 12L) −(Ti/2) −pr ω2 1 sin
θ --- (2a), which similarly produces a longitudinal bias around the Y axis.

In addition, the counterweights 6a, 6b, and 6c have components not only in the Z direction 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. .

-(Ti/2) spr ω2 1. cos
θ---(2b) That is, a longitudinal couple around the Z axis is generated due to the force in the Y direction.

Above, the counterweights 6a to 60 on the crankshaft side
The inertia couple in the potato direction generated by this occurs around the Y wheel in two directions and around the Z wheel in the Y direction, and the combination of both is as follows.

(Ti/2)mpr ω2 Lsin θ
−(Ti/2) aprXω21cosθ −(Ti/2 ) aprω2 1 (sin
θ-cos θ)・・・・(3) By the way, in addition to providing the above-mentioned crankshaft side counterweight for each cylinder, it is also separately assembled in the first and third cylinders on both sides except for the second 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, omitting the transient details, 6σ on the counterweight side of the first and third cylinders is (Ti/2) (II)
/2), and the counterweight of the first cylinder is
This is a position further 30° in phase than the position where the crank arm 2a is 180° in phase, and the third cylinder counterweight 6d is 30° behind the position in which it is 180° in phase from the crank arm 2C. provided at the location. That is, both counterweights 6m and 8(' are positions 180 degrees opposite to the crankshaft 1 and perpendicular to the central crank arm 2b.

In this case as well, the force F real due to the quality of each counterweight in two directions when it moves by θ from the state shown in the figure.
', l''rec3' is 9-Frec1'-(Ti/2) (IEI/2
) r ω2xcos(θ+240 +180 +
30) Frec3' - (J'j/2) (m
p/2) r ω2xcos(θ+120
+180 -30)°, and the inertial force in two directions becomes F real' + F rec3' -0, which naturally balances out.

Then, the longitudinal inertia couple due to the forces in these two directions is Frecl'-8+Frec3' (S+2 L
) = (Ti/2) -pr ω2 1 s
tn θ, which agrees with equation (2a).

The inertia forces are also balanced in the Y direction, and the longitudinal inertia couple due to the force in the Y direction matches equation (2b).

From this, even if one counterweight on the crankshaft side is provided for each cylinder, or one only for the 1st and 3rd cylinders, the inertia force will be balanced, and the inertia couple in the direction It is understood that they will be the same.

As mentioned above, the reciprocating mass on the crankshaft, balance of inertia force due to counter weight, longitudinal inertia couple,
In other words, although we have explained the whirling, the longitudinal couples of equations (1) and (3) remain, and when they are combined, -Jiapr ω2 1 sin θ + (Jj
/2) -pr ω2XL(sinθ-COS
θ) = −(J'j/2) g+pr oo2
1 (sin θ + cos θ)...(4
) becomes. 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 quality of each balancer 8a to 8C is -M2 with respect to the reciprocating mass on the crankshaft side. In addition, 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 bottom dead center -〇 position, and the balancer 8a corresponding to the first cylinder is at the opposite position -〇.
is further 1800 from the position where the phase has advanced 2400 in the counterclockwise direction.
In the shifted position, the balancer 8C corresponding to the third cylinder is rotated counterclockwise 1
It is at position 1, which is further 180' phase advanced from the 20° position.

The force F recl, F r”ac2. F rec3
is F recl-, (mp/2) r ω2 c
os (θ+240 +180) Frec2-
(sp/2) r ω2 cos (θ
+180) Frec3- (+ep/2)
r ω2 cos (θ + 120 +
180 ), the inertia forces in two directions are balanced, and the 'longitudinal couple around the Y axis due to this force in the Z direction is (ffi/2) spr ω2 1 sin
θ - - (2a') Also, in the Y direction, the polarity is 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 7 wheels due to this Y direction force is ,
(j'N/2) aprω21JO8θ...(2b'
) Therefore, the inertia couple in the longitudinal direction generated by the balancers 8atl to 8c on the balancer shaft side also occurs around the Y wheel in two directions and around the 7 wheels in the Y direction, and the combined force is expressed by the above equation (2a') and ( 2b') The equation becomes as follows.

(5/2) spr ω2 L (sinθ+cosθ
)...(4') By the way, 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 the balancer corresponding to U and 3rd cylinder is mp/
2 multiplied by word/2, the one corresponding to the first cylinder is located further ahead in phase by 3G", and the one corresponding to the third cylinder is located further behind in phase by 30". This gives the same result as in Figure 5, and can be replaced by that.

As mentioned above, the balance of inertial 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 inertia couple in the longitudinal direction due to the reciprocating mass generated on the crankshaft side and the mass of the counterweight that half-balances it. 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 the three-cylinder engine.The configuration is the same as in Figure 2,
h, Fc1. acting on the 1st to 13th-3rd cylinders at the position moved by θ. Fc2. Fc3 is as follows.

Fc1--ar ω2 cos (θ +240
) Fc2 company marω2 (itsθ F c3= marω2cos(θ +120)
As a result, the longitudinal couple around the Y axis due to the rotating mass is −J
jmcr ω2Lsinθ ---(5a) The longitudinal eccentric force around the two axes is Jjmcr ω2 Lcos θ ---(
5b)k, which similarly occurs around the Y axis in two directions and around the Z wheel in the Y direction, and when combined, it becomes as follows.

−JNscr ω2 L (sin θ −co
s θ )---(6) Next, a counterweight 6 is used to balance the rotational quality at a ratio of 1:1 for each cylinder.
To explain the balance by mass of a to 6C,
The configuration is the same as that in FIG. 3, and the forces due to each counterweight mass, Frotl, Frot2. l” rOt
a becomes as follows.

Frotl-mar ω2 cos (θ +
240 +180) F rot2= mcr
ω2cos (θ +180)14- Frot3--ar (132008(θ +120
+180) As a result, the longitudinal eccentric force around the Y axis in two directions becomes j'1lcr ω21-8inθ −
--(7a) The longitudinal eccentric force around the two wheels in the Y direction is -ff*cr ω21coaθ --, -(7b), and the whirling that is a combination of both is as follows.

I'1l(jr ω2 1 (sin θ−co
s θ ) --(8) By the way, also in the case of such a rotating mass, as shown in Fig. 4, the mass is partially < m/2
), and by advancing or delaying the 3G' 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-axis and Z-axis in equation (6) becomes zero by combining with the similar longitudinal bias force 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.As is clear from the above explanation, the engine has a reciprocating part and a rotating part for each cylinder. An inertial force and a couple are generated due to the mass of the cylinder, and when balancing these two types of mass, there are cases in which they are concentrated separately for each cylinder and on the first and third cylinder sides, respectively. Therefore, it is possible to solve the problem by lumping these two types of masses together and using two types of balancing methods, but it may be preferable to use different balancing methods for each mass.

Therefore, in the crankshaft 1, first, for each cylinder, counterweights 6a-1 and 6a-2゜eb for the mass of the reciprocating part are calculated.
-1 and 6b-2, 6cm1 and 60-2 are provided on the opposite side of each crank arm from the crank pin as shown in FIG. Next, as for the mass of the reciprocating part, as shown in FIG. 4, counterweights 1-f-1 and u-2, fsr! are placed at two locations in the first and third cylinders excluding the second cylinder! −, and 6σ
-2 is also provided. In addition, the balancer shaft 1 only needs to balance the unbalanced masses of the reciprocating parts, and for this reason, it is based on the technical idea as shown in Fig. 5, and in this case, for example, the crankshaft is used as the part corresponding to the first and third cylinders. 1
The balancers 8a, 8c, which are independent of the inner and outer bearings 9a and 9d of the crankshaft 1, select the two inner bearings 9b and 9c of the crankshaft 1 as the part corresponding to the second cylinder. Balancer ab-1, a divided into two parts
A part of these balancers also serves as a bearing.

In such a configuration, when considering the balance on the crankshaft side, the counterweight side -1 and d with respect to the mass of the rotating part.
-2,8c'-1 and sc'-2 are separated and concentrated in two places, so it is enough to multiply the combined mass of each cylinder by (IN/2) and adjust the phase by 30 degrees. , the pitch of each cylinder is as shown in Fig. 2, then for longitudinal eccentric force, @C(Jj/2) x 2L = Jjs
It is sufficient to generate cL.

Therefore, the resultant mass of counterweight * -t, 6(-a is Mca', counterweight FM!, -x
, 61'-a is the combined mass of M QC', taking into consideration the balance of the inertial force on the crankshaft 1, Mea'-=
Hold Mcc”tr and counterweight Ba-1 and Ba-2
The resultant weight 17- for the Y-axis of
-2's composite center of gravity relative to the Y axis is L+y', then Mca' (L + x' +L+ y') -
Since it is sufficient to satisfy JNscL, the following general formula is obtained.

Mea'-Mcc' -JNmcL/ (2L
+ x' + y' )...(9a) Next, the counterweight 6 liters for the mass of the reciprocating part
and 6a-2, 6b-1 and 6b-2, 6cm1 and 60-2
-) iT is the respective synthetic material Mca, Mc
b, Mac, then Mca-Mcb-Mcc is maintained in consideration of the balance of inertial force on the crankshaft. Further, the counterweight ea of the first cylinder with respect to the combined center of gravity position of the counterweights 6b-1 and 6b-2 of the second cylinder,
The resultant center of gravity position of
Then, X−ν is held by Mca(L+x)−Mac(L+y).

Then, for the longitudinal couple, take out the Y direction component, (Mca(L+ x) +Mcc(L+ y))
It is sufficient to satisfy 0083018--(, th/2) DL, and the following general formula is obtained.

Mca-Mcb-Mac-(1/2)■EEL/(
L+x)...(9b) As mentioned above, each counterweight mass can be arbitrarily determined in relation to the composite weight 6th place 1, and both are based on the composite center of gravity position x/
, vl, x, and y, the larger the distance, the smaller the mass will be. To make it easier to understand, let's make the center of gravity of the first and third cylinders the same, and the center of gravity of the second cylinder, so that x'-y' -x
-y -0, the counterweight mass at two locations in the first and third cylinders relative to the mass of the reciprocating part is (j'j/
2) Peng is C, and the counterweight mass at the three locations of the first to third cylinders relative to the mass of the reciprocating part is (1/2
>-El.

Further, in the first and third cylinders, counterweights for both the rotating and reciprocating mass are provided separately at an angle of 30°, but in reality, they are vector-combined into a single counterweight.

Next, on the balancer shaft 1, it is sufficient to half-balance the reciprocating mass of the engine with a mass of -p/2 in the portion corresponding to each cylinder. Therefore, the mass of balancers 8a and 8c is Mb
a, Mbc, and a balancer gb-, which is divided into two parts.
, the composite mass of gb-2 is Mbb, and the central balancer a
b, Balancer a for the combined center of gravity position of 8tL2
a, the position of 13c is l +x/l, L +V//
Then, considering the balance of inertial force on the balancer axis,
M ba −M bb −M be x”−Vu is retained.

In addition, for the longitudinal bias, take the Y-direction components of the first and third cylinder side balancers 8a and 8c, and calculate (Mba(L+
x″) 10Mbc(L+y″)) cos
It is sufficient to satisfy the relationship: 30=(N/2)-pL, resulting in the following general formula.

Mba-Mbb=Mbc-spL/2(L+x”
)... Qllll) Therefore, even if the pitch of 9c and 9d with respect to the bearings 9a and 9b of the crankshaft 1 is true, the central balancer 8b-
By selecting the combined center of gravity position of 1 and 8b-2, four balancers 8a, ah-1, 8b-2, 80 are connected to bearings 9a, 9.
b, 9c, 9d, and if the bearing side has the same pitch, the balancers ab-i, 8b
This can be easily done by equally dividing the quality of -2. In addition, since the balancers 8a and 8c are offset outward from the center of the first and third cylinders, the quality of the balancer can be smaller than if the center were the corresponding part of each cylinder. 8a, 8b-1, 8b4, and 8c aim to make effective use of the space in the bearing section.

In this way, in the crank wheel 1, the first and third cylinders (9a
) counterweight u-1 and side-2,6 of the resultant mass of the equation
1'-1 and 66-2 are provided at right angles to the crank arm 2b of the second cylinder, and
b) Counterweight 6a, 1 and 6a- of the combined mass of formula
2.6 cm1 and 60-2 are provided on the opposite side of the crank pin of each crank arm. Further, in the balancer shaft 1, the balancers 8a and 8b are the first bearing and the third bearing 9a is the fourth bearing.

Balancer 8b-m, 8 divided into two at the corresponding part of 9d
b-2 is the corresponding part of the second cylinder bearings 9b and 9c (2)
) is half-balanced due to the quality of the equation, which balances the inertial force and couple due to the masses of the reciprocating and rotating parts of the three-cylinder engine.

And the balancers 8a, 8b-1, 8b-2
, 8c are arranged in the part corresponding to the wheel bearing which is shifted from the counterweight position of the crankshaft 1, and interference with the counterweight is avoided. Therefore, the balancer shaft 7 can be set as a counterweight without considering the existence of the balancer. Due to the relationship with the chisel, it is possible to have two angles closer to the crankshaft 1 side.

In the above embodiment, the balancer for the part corresponding to the second cylinder is divided into two parts, but one of the crankshaft bearings 9b and 90 is selected as the part corresponding to the second cylinder, and the balancer is divided into two parts for the part corresponding to the second cylinder. A considerable portion of the balancer can also be divided into two parts.

Furthermore, in a total of four balancers 8a, 8b-1, 8b-2, and 8c, one independent and one divided into two,
In order to properly support the balancer shaft 1, the inner and outer 2
The balancers 8a and 8c are also used as bearings. Therefore, to explain in detail with reference to Fig. 8, first, balancer shaft 1
The shaft tube 20 is housed in a shaft tube 20 having a circumferential shape centered on the shaft, and the shaft tube 20 and the bearing 9a are fitted and assembled into a shaft support 22 having a 22-way connection through a metal 21. balancer 8c
The balancer shaft 1 is constructed in exactly the same manner and is assembled to the common shaft support 24 with the bearing 9d, so that the balancer shaft 1 is connected to the bearing 9b for the two inner balancers 8L1 and 8b-a.

The 9C equivalent part is free, but the balancer 8a on both sides.

Since the bearing 23 having the above-described configuration in 80 is rotatably supported on both sides, there is no need to provide an external bearing.

By doing so, vibrations etc. are greatly reduced. Since we treat the factors depending on the quality of the regular part and the rotating part separately, and use different balancing methods for each, we simply clarify the balance system as a whole. Since the counterweights formed by the rotating mass are provided separately from each other only in the first and third cylinders on the crankshaft 1, the quality of the entire counterweights can be reduced compared to a case where the counterweights are provided for each cylinder. Adding generality to the installation of counterweights and balancers increases confidence in the design. Furthermore, since the balance 8C is arranged at a distance from each other in the portion corresponding to the crankshaft bearing, the balancer shaft 1 can be brought closer to the crankshaft 1 by effectively utilizing the space of the bearing, contributing to miniaturization. The balancer mass itself can also be small.

In addition, some of the balancers 8a and 8c have built-in bearings and also serve as bearings for the balancer shaft 1.
As a result, the bending moment generated in the balancer is reduced, making it possible to reduce the diameter of the balancer shaft in terms of strength and reliability. Providing the bearing of the balancer shaft 7 at a portion corresponding to the shaft end of the crankshaft bearings 9a, 9d, etc. is a location with high rigidity for the engine, and can prevent problems caused by elastic vibration of the engine due to repeated loads. Furthermore, even in cases where the balancer shaft 7 is partially submerged in oil due to the mounting position of the engine, since the balancers 8a and 8c are housed in the entire circumferential shaft tube 20, the resistance due to oil agitation is increased. Oil spray etc. can be prevented.

In this case, the inner balancers 8tL, , 8b-2 can also be equipped with shaft tubes, and the above-mentioned effects can be further improved.
Increase.

A specific example of the balancer shaft installation will be explained with reference to FIG. 9. When the engine is installed under the loading platform using the R-R method as shown in the figure, the engine body 10 is restricted by the loading platform 16 and is placed in a vertical position. It is installed at a considerable angle from the
On top of the engine body 10 in this position are an air cleaner 11, a carburetor 12, an intake system including an intake pipe 13, a cooler compressor 14. AC015 etc. are arranged. Therefore, the upper part of the engine body 10 is limited by the various auxiliary equipment mentioned above, and when the balancer shaft 1 is installed downward as shown in the figure, the balancer shaft 1 is located below the crank wheel 1 and is partially submerged in oil. In such a case, the above-described effects of the present invention 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 part, and FIG. FIG. 2 is a side view showing a specific example when applied to a moving vehicle. 1... Crank shaft, 2a, 2b, 2c... Crank arm, 6a-, 6a-2, 6b-1, 6b-2, 6
cm1.6cm2. ar-1,5(-2゜ec'-1
, 5 (-2... Counterweight, 1... Balancer shaft, 8a, 8b-1, -8b-2, 8cm... Balancer, 9a, 9b, 9c, 9d... Crankshaft bearing, 20... ...Axis tube, 21...Metal, 22゜24・
... shaft support, 23... bearing. Patent applicant: Fuji Heavy Industries Co., Ltd. Representative Patent Attorney Nobuko Maki Udo Patent Attorney Susumu Murai 26-

Claims (1)

[Claims] The first and third cylinders of the crank koji, whose crank arms are sequentially arranged at equal intervals of 120 degrees, have a counterweight for the reciprocating and rotating mass of the engine, and the second cylinder has a counterweight for the reciprocating mass of the engine. one balancer device rotating in the opposite direction at the same speed with respect to the crankshaft; one crankshaft bearing equivalent part for each of two of the first to third cylinders on the balancer shaft; An independent balancer is installed at the two locations, and a split balancer is installed at the two locations where the two crankshaft bearings of the remaining cylinder meet for half-balancing. A balancer device for a 3-cylinder engine characterized by two of them serving as bearings.