JPS5839842A - 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 all of them are made to 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 revolving parts and reciprocating 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 revolving parts. Further, a balancer shaft 7 is installed for revolving in the inverse direction at the same speed as the crankshaft 1, balancers 8a, 8c are installed in the zone corresponding to the bearings 9a, 9d of the first and third cylinders, and balancers 8b-1, 8b-2 which are divided into two parts are installed on the zone corresponding to the bearings 9b, 9c of the second cylinder. Then, all the balancers 8a-8b are supported in a full-circumferential shape of shaft pipe, and they are used also as bearings 23.

Description

[Detailed Description of the Invention] The present invention provides an automatic three-cylinder engine with a crankshaft and a balancer shaft that rotates in the opposite direction at the same speed as the crankshaft. , the first-order inertia force due to the U-return and rotating mass of each cylinder was balanced with the first-order inertia couple around the X-axis, and in addition, the first-order tlI couple in the longitudinal direction of the crankshaft was also balanced. This paper relates to balancer devices.

In each cylinder, there is an inertia force due to the reciprocating mass and rotating mass, and the inertia due to the rotating mass can be balanced out by installing a counterweight on the opposite side of the crank arm. The inertial force is balanced at the same position as when it is caused by a rotating mass, and the remaining part is balanced by a balancer shaft that rotates in the opposite direction at the same speed as the rank shaft. In this case, the inertial forces of each cylinder plow are balanced as described above, and at the same time, the inertial couple around the X axis is balanced, and an inertial couple in the bN direction is generated.In order to balance and eliminate this inertial couple, In the past, for example, the counterweight of the crankshaft was separated into a specific configuration as in Japanese Patent Application Laid-Open No. 55-60341 S=J, or the inertial couple of the crankshaft system was large as in Japanese Patent Publication No. 54-2333@. There is one that generates an inertia couple of the same force but in opposite directions 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 left and right sides of the middle second cylinder. The inertia couple in the longitudinal direction of the shaft must be taken into consideration, and this has a large effect on engine vibration. On the other hand, the longitudinal 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 depending on the lead part on the balancer shaft side. Therefore, by specifying the mounting position 1 of the balancer, it will be very advantageous in terms of the structure of the balancer shaft itself, the degree of freedom in installation, the arrangement W relative to the crankshaft, etc.

In view of these circumstances, the present invention aims to balance the inertial force and the couple by using the balancer of the crankshaft and the balancer shaft, and also to bring the balancer shaft closer to the crankshaft side and to reduce the size of the light plow. It is an object of the present invention to provide a balancer device for a three-cylinder engine.

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings. First, let us 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 ``rod'', 5 is a piston, and a counterweight 6 is installed on the extension line of the crank arm 2 on the opposite side from the crank bin 3 to half balance the entire inertia force due to the rotating mass and the inertia force due to the reciprocating mass. In addition, one balancer shaft 7 that rotates in the opposite direction at the same speed as the crankshaft 1 is provided, and a balancer 8 is provided that half-balances the remaining part of the inertia (J) due to the reciprocating portion #A. As shown in the figure, when the crank arm 2 is rotated by θ from the upper part of the Z-axis, the balancer 8 of the balancer shaft 7 is provided so that it is rotated 4 times by the same angle θ from the lower part of the Z-axis. here,
If the inertial mass of the reciprocating part is lp, and to make the explanation easier to understand, the equivalent inertial mass of the rotating part crankbin 3 is -0, then the mass of the counterweight 6 on the crankshaft side is ti relative to the inert mass p. Since it is sufficient to half-balance ip/2, for rotating mass -C, crankshaft 1
Since it rotates in the same direction as , all of them can be balanced and become IO, and the total becomes (mp/2) 10-C. Further, the mass of the balancer 8 on the balancer shaft side becomes the remainder of the above-mentioned reciprocating mass and becomes sp/2.

By doing this, the inertial forces in the 2°YZj directions of the reciprocating portion and the rotating portion are balanced. Therefore, in a three-cylinder engine, if a counterweight 6 and a balancer 8 of each mass are attached to positions corresponding to each cylinder, then
In this case, the total mass of the counterweight on the crankshaft side is 3 ((■p/2)+C), and the total balancer weight on the balancer shaft side is (3/2)mp.

Next, the balance due to the mass of the reciprocating part in a three-cylinder engine will be explained with reference to Fig. 2. In Fig.
, and the second cylinder is at top dead center, the first cylinder is rotated 240 degrees from it, and the third cylinder is 120"
It is in a rotated position.

Therefore, when the cylinder moves by θ from this state, the excitation force Fpl of the first cylinder, the excitation force Fl12 of the second cylinder, and the excitation force Fp3 of the third cylinder are as follows.

Fpl=mpr oo2 cos (θ+240)F
p2=apr ω2 cosθ Fp3=-enpr ω2 cos (θ +
120) Therefore, the total inertial force is balanced by F p1+ F t+2+ F p3=0.

In addition, in order to give the inertia couple in the longitudinal direction of the crankshaft a -membrane property, we will look at it 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・S+Fp2(S+L ) (Fp3(S+2
L).

That is, 6-Fpl・S+Fp2(S+L)+Fl)3(S+2
L)=-ffapr ω2 1 sin θ---(
1), a longitudinal bias force around the Y axis is generated due to the reciprocating mass which is the Z direction load.

To explain the balance by mass of counterweights 6a, 6b, and k 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 6a
, ab, 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 forces due to each counterweight mass Frec1, l'' rec2, F
rec3 becomes as follows.

Frecl −(−p/2) r ω2 c
os (θ +240 + 180) F re
c2- (sp/2) r ω2 cos
(θ +180) Frec3- (g+p/2
) r (Z)2 008 (θ +120
+ 180 > Therefore, the inertial force in the Z direction is Frecl+ Frec2+ l" rec3- Q
The balance becomes 4.

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, Frecl-S+ Frec2(S+ 1) + F
rec3(s+2L) = <m/2) i+pr oo2 1 s
in 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. .

-(Ji/2) spr w2 1 cos
θ---(2b) That is, a longitudinal bias force 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 longitudinal direction generated by this occurs around the Y wheel in the Z direction and around the Z axis in the Y direction, and the combined force of both is as follows.

(j'N/2) g+pr ω2 Lsin
θ − (J”i/2) aprXω21cos
θ = (Jj/2) mprω2L (sinθ−c
osθ)・・・・(3) By the way, in addition to providing the above-mentioned crankshaft side counterweight for each cylinder, it is also possible to separately provide the counterweight on the first and third cylinders on both sides except for the second cylinder in the center. This is also possible, and this case will be explained with reference to FIG. To state the results without explaining the progress in progress, the counterweights of the first and third cylinders, 6d, are <m/2) (■p/2)
With a mass of
This is the position where the phase is advanced, and the counterweight 6 of the third cylinder is 180° phase advanced from the crank arm 2C.
It is provided at a position delayed by 30' phase. That is, both counterweights &1. ．． 6 (' is 18 for crankshaft 1
This position is 0° in the opposite direction and perpendicular to the central crank arm 2b.

In this case as well, Z when moving by θ from the state shown in the figure
Force F rec1' due to each counterweight mass in the direction
, F rec3' is 1"recl'-Us/
2) (II)/2) r ω2xco
s(θ+240 +180 +30>9- Frec3' = N'j/2) (g+p
/2) r ω2xcos(θ+120 +180
-30), and the Z-direction inertial force becomes Frec1' + Frec3' = 0, which naturally balances out.

Next, the longitudinal inertia couple due to this force in the Z direction is Frecl'・S+Frec3' (S+21)
= (ffi/2) apr ω2 1 sin
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, it can be seen that although one counterweight on the crankshaft side is provided for each cylinder, or even if one is provided only for the 1st and 3rd cylinders, the inertia forces are balanced and the inertia couple in the longitudinal direction It is understood that they will be the same.

Above, we have explained the balance of inertia force due to the reciprocating mass and counterweight on the crankshaft, and the longitudinal inertia couple, that is, whirling, but here 10- (1) 2 and (3) longitudinal bias force remain. and when combined, -E g+pr ω21sin θ + (H/2
) mpr ω2X[(Sinθ−COSθ) =−(Jj/2) spr w2L (sinθ+
cos θ)...(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 8C is -p/2 with respect 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 8a corresponding to the first cylinder is at the opposite position.
is further 180° from the position where the phase has advanced 240° counterclockwise.
The balancer 8G corresponding to the 3rd cylinder is rotated counterclockwise in the shifted position.
It is at position 1, which is a further 180° phase advance from the 120° position.

Therefore, the force F in two directions when moving by θ from this state
recl, F rec2. F rec3 is
ec1= (gtp/2) r Co2 cos
(θ+-240+180) Frec2- (B/
2) rCo2 cos (θ −1−
180) 1-rec3= (sp/2) r w
2 cos (θ+-120+ 180 > So, the two-direction inertia forces are balanced, and the longitudinal eccentric force around the Y-axis due to this Z-direction force is (j'j/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 eccentric force around the 7 wheels due to this Y direction force is ,
(Shi/2) apr Q)2 L COSθ--(
2b') Therefore, balancers 8a to 8C on the balancer shaft side
The inertia couple in the longitudinal direction generated by .

(J'N/2) -pr Co2 L,
(sin θ + Cos θ)...(4'
) By the way, the balancer on the balancer shaft side can also be separated and assembled in the same way as the balancer on the crankshaft side in FIG. 4. To explain this case with reference to FIG. The mass of the balancer is 1p/2
is multiplied by month/2, and the cylinder equivalent to the first cylinder is positioned further ahead by 30 degrees in phase, and the cylinder corresponding to the third cylinder is positioned further behind by 30 degrees in phase. This gives the same result as in Figure 5, and can be replaced by 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, it can be seen that the longitudinal inertia due to the residual mass generated on the crankshaft side and the mass of the counterweight that half-balances it. The couple is 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.

13- 13-Fc1= Co2 cos (θ 14
0) Fc2 = mcr Co2 cos θFc
3=scr w2 cos (θ +120)
As a result, the longitudinal eccentric force around the Y axis due to the rotating mass is -H
ear ω21 sinθ --- (Sa) The longitudinal eccentric force around the 7th wheel is
Similarly, it occurs around the Y axis in two directions and around the two wheels in the Y direction, and when combined, it becomes as follows.

-Hear Co2 1. (sin θ −c
os θ )---(6) Next, a counterweight 6 is used to balance this 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, F rotl, F rot2 . F rot
3 becomes as follows.

F rotl= lcr ω2 cos (θ
+240 −+ 180) Frot2=mcr
ω2 cos (θ + 180)FrOt
3= lcr ω2cos(θ →, 12o +
180 > As a result, the longitudinal bias around the Y axis due to the Z direction becomes 14- 1'1scr ω2 1sin θ --
-(7a) The longitudinal bias around the two axes in the Y direction is -jNg+cr ω2 Laos θ
・ ・ ・ (1b) becomes, and the whirling longitudinal couple that combines the two becomes as follows.

finer cc>21 (sinθ−COSθ) −
-(8) By the way, even in the case of the rotational quality (2), as shown in Fig. 4, by multiplying the mass IC by l/2) and advancing or retarding the phase by 30 degrees, the counters can be applied to the first and third cylinders. It is possible to separate and concentrate sea urchins and sea urchins.

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. An inertial force and a couple are generated due to the masses of the rotating parts, and it is of course possible to balance these masses by putting them together. However, especially regarding the quality of the rotating parts (2), considering that it is possible to balance the inertial force and the couple only with the counterweight on the crankshaft side, it is possible that this characteristic is due to the mass of the rotating parts. It is preferable to treat these separately from the mass of the reciprocating part, which can only be balanced by using the balancer shaft in combination.

Therefore, in the crankshaft 1, first, counterweights 6a-1 and 6a-2 are applied to the mass of the rotating parts for each cylinder.
, 6L1 and 6b-2, and 6cm1 and 60-2 are provided on the opposite side of the crank pin of each crank arm as shown in FIG. Next, as for the mass of the reciprocating part, as shown in FIG.
-a is also provided. In addition, the balancer shaft 7 only needs to balance the unbalanced reciprocating part due to the tension, and for this reason, it is based on the technical idea as shown in Fig. 5, and in this case, the first and third cylinders □ The crank The balancer 8a selects the bearings 9a, 9d on both sides of the shaft 1 and provides independent balancers 8a for those locations.

8C is a part corresponding to the second air crane, two bearings 9b and 9c inside the crankshaft 1 are selected, and balancers 81)-1 and 8b-2, which are divided into two parts, are provided at these locations. A part of the balancer is also used as a bearing.

In such a configuration, considering the balance on the crankshaft side, the counterweight for *** of the reciprocating part -1
As for fin-2, 6σ-1 and 6σ-2, they are separated and concentrated in two places, so the combined mass on each cylinder side is (
It is sufficient to multiply ip/2) by (old/2) and adjust the phase by 30°.If the pitch of each cylinder is set to 1 as in Fig. 2, then for the longitudinal couple, (p/2) (Month/2)X2L = (Month/2) wp
It is sufficient to generate L.

Therefore, the composite quality of counterweights fJ-1, 6j-2 is Mca', counterweight 6('-t,
If the combined mass of 611'-2 is M CC', considering the balance of inertial force on the crankshaft 1, M ca' -
Hold M CC' and counterweights F-i-1 and 6
If the resultant center of gravity position for the Y-wheel of i-2 is l+x', and the resultant center of gravity position for the counterweights 6-1 and 6C'-217- for the Y axis is l+y', then M
ca'(L+X'+L+y') = (
Takumi/2) If spL is satisfied, then the following general formula is obtained.

Mca' = Mcc' = <R/2)i+
pl.

/(2L+X'+V')・
・ ・ (9a) Next, h lantern weights 6a-1 and 6a-2, 6b-1 and sb for the mass of the rotating part,
For 6cm1 and 6cm2, if the respective combined masses are MCa, Mcb, and Mcc, then considering the balance of inertial force on the crankshaft, Mca=Mcb-
= Hold M cc.

In addition, the second cylinder counterways 1-eb-1 and 6b-
If the combined center of gravity position of the counterweights 6a-1 and 6a-2 of the first cylinder with respect to the combined center of gravity position of the second cylinder is L+V, and the combined center of gravity position of the counterweights 6C-1 and 60-2 of the third cylinder is L+V, x=y is maintained by Mca(L+x)=Mcc(L+y).

Then, for the longitudinal couple, take out the Y direction component, (Mca(L+ x), +Mcc(L+ y))
It is sufficient to satisfy cos30-18-=j'5*cl, resulting in the following general formula.

Mca=Mcb=Mcc=scL/ (L + x)・
...(9b) Therefore, the mass of each counterweight can be arbitrarily determined in relation to the composite center of gravity position, and in both cases, the mass increases as the values of the composite center position xI, y/, can be small. To make it easier to understand, the positions of the centers of gravity in the first and third cylinders are the same, and
By aligning the center of gravity in the cylinder with the center, x' - y
' = xy -0, the quality of the counterweights at the two locations in the first and third cylinders relative to the quality of the reciprocating part becomes (IN/4)sp, and the
The quality of the counterweights at three locations on the third cylinder is ■C
becomes.

Further, in the first and third cylinders, the image amounts of the reciprocating portion and the rotating portion are set at an angle of 30°, but in reality, a single image is provided by vector-synthesizing these.

Next, since the balancer shaft 7 balances the reciprocating mass of the engine for each cylinder-corresponding part, it is sufficient to half-balance each cylinder-corresponding part with a quality of mp/2. So balancer 8a.

The quality of 8C is Mba, Mbc, the combined mass of the two divided balancers 5b-1 and ab-2 is Mbb, and the balancer 8a is relative to the combined center of gravity position of the central balancers gb-1 and 5b-2. 8c position L + X'',
L+V", considering the balance of inertial force on the balancer axis, Mba=Mbb=Mbc x"=
y” is retained.

Furthermore, for the longitudinal couple, take the Y-direction components of the balancers 8a and 8Q on the first and third cylinder sides, and calculate fMba(L+
x”) 10Mbc(L+y”)) co
It is sufficient to satisfy the relationship s30=(r:4/2)iipL, resulting in the following general formula.

Mba=Mbb=Mbc-i+pL/2 (L-
1-X'')... ([l) Therefore, even if the pitches of 9G and 90 for the bearings 9a and 9b of the crankshaft 1 are different, the central balancer gb
and 8b-2, the four balancers 8a, 8L1, 8b-2, 8c are connected to the bearings 9a, 9b.
, 9c, and 9d, and if the pitches on the bearing side are equal, this can be easily done by equally dividing the width of the balancers gb-1 and ab-2. In addition, since the balancers 8a and 8c are offset outward from the center of the first and third cylinders, the balancer trade is smaller than if the center were the corresponding part, and all the balancers 8a and 8c are shifted outward. , 8L1, 8b-2, and 8c aim to make effective use of the space in the bearing section.

In this way, on the crankshaft 1, the first and third cylinders (9a
) counterweights u-1 and tJ-a of the combined mass of the equation,
6σ-1 and 1-2 are provided at positions perpendicular to the crank arm 2b of the second cylinder, and in the first to third cylinders (9b
) Counterweights 6a-1 and 6a-2 of the combined mass of the formula
, 6cm1 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 8o are bearings 9a for the first and third cylinders.

Balancer 8b-1, 8b- divided into two parts in the 9d equivalent part
2 is half-balanced at the portion corresponding to bearings 9b and 9c of the second cylinder due to the quality of the (support)) equation.
The first order due to the trade between the reciprocating part and the rotating part of the cylinder engine =
21- The inertial force and inertial couple are balanced.

And all balancers 8a, 8L1, 8b-2
, 8c are arranged in the bearing equivalent part of the crankshaft 1 which is shifted from the counterweight fQH to avoid interference with the counterweight. Therefore, the balancer shaft 7 can be used as a counterweight without considering the existence of the balancer. It is possible to arrange the GJ close to the crankshaft 1 side due to the relationship with the GJ.

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 9c is selected as the part corresponding to the second cylinder, and the balancer is divided into two parts. It is also possible to divide the balancer for three cylinders 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 support the balancer shaft 7 well, the inner and outer two
The balancers 8a and 8c are configured to also serve as bearings. To describe this in detail with reference to FIG. 8, first, the balancer shaft 7 is built into a shaft tube 20 having a full circumference shape, and this shaft tube 20 is connected to a shaft support 22 through a metal 21 with the bearing 9a through the shaft support 22. Fitted and assembled. balancer 8c
The balancer shaft 7 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 7 is connected to the two inner balancers 81L1 and 81L1 and the bearings 9b and 9 for the ab-2.
A corresponding portion of c is free, but the inner and outer balancers 8a.

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

By doing so, vibrations etc. are greatly reduced. Former IIs
We treat the mass of the rotating part and the mass of the rotating part separately (\, especially the mass of the rotating part is balanced by the counter and weight of the crankshaft cylinder, so let's simplify and clarify the lance system as a whole. Reciprocation Since the counterweights based on mass are provided separately from each other only in the first and third cylinders on the crankshaft 1, the mass of the entire counterweight can be smaller compared to the case where the counterweights are provided for each cylinder.Counterweight and balancer By adding generality to the mounting of the
2.

8C are arranged at a distance from each other in the part corresponding to the crankshaft bearing, making effective use of the space in the bearing part, making it possible to bring the balancer shaft l closer to the crankshaft 1, contributing to miniaturization and improving balancer quality. The sake itself is small and performs well.

In addition, the balancers 8a, 8b-1, 8b-2,
Since 8c is transversely moved with a built-in bearing and also serves as a bearing for the balancer shaft 1, the bending moment generated on the balancer shaft 7 is reduced, making it possible to reduce the balancer shaft diameter in terms of strength and reliability. expensive. The fact that the balancer shaft 70 bearing is installed in the bearing equivalent parts of the crankshaft bearings 9a, 9b, 9c, 9d, etc. is a location with high rigidity in the engine, and the elastic vibration of the engine due to repeated loads Inconveniences can be prevented from occurring.Furthermore, even in the case where the balancer shaft 7 is partially submerged in oil due to the mounting position of the engine, the balancer 8a, 8L1, 8 can be mounted on the pan.
Since b-2 and 8c are accommodated in the entire circumferential shaft tube 20, an increase in resistance due to oil agitation, oil spouting, etc. can be prevented.

A specific example of the balancer shaft installation 1 will be explained with reference to FIG. 9. When the engine is assembled under the cargo bed using the R-R method as shown in the figure, the engine body 10 is attached to the cargo bed 16.
The air cleaner 11, the carburetor 12, the intake system of the intake pipe 13, the cooler compressor 14, the ACG 15, etc. are arranged on top of the engine body 10 in this position. . Therefore, the illumination of the upper part of the engine body 10 is limited by the above-mentioned various auxiliary equipment, and when the balancer shaft 1 is installed downward as shown in the figure, the balancer shaft 1 becomes 9 parts below the crankshaft 1, and some oil is removed. In this case, the above-described effects of the present invention are exhibited.

-4. Brief explanation of the drawings Figures 1 to 6 are explanatory diagrams 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 cross-sectional view showing a specific example of the IN section, and Fig. 9 is an application of the present invention to a 25-car vehicle. It is a rr@ side view showing a specific example of the case.

1... Crankshaft, 2a, 2b, 2c... Crank arm, 6a-1+ 6a-2, 6b-4, 6b-2,
6c, 4.6cm2. Fd-1,6za-2゜6C'
-1, 6['-2...Counterweight, 1...Balancer shaft, 8a, 8L1, 8b-2, 8cm...Balancer, 20...Shaft tube, 21...Metal, 22
．． 24.25.26...Axle support, 23...Bearing.

Patent applicant: Fuji Heavy Industries Co., Ltd. Representative Patent Attorney Nobuoki Kohashi Same patent attorney Susumu Murai 26-1 \( Figure 8

Claims (1)

[Claims] The first and third cylinders of the crankshaft, in which the crank arms are sequentially arranged at equal intervals of 120 degrees, have a counterweight for the engine's L1 return σ rotational mass, and the second cylinder has a counterweight for the engine's rotational quality. Only a counterweight is provided, and a balancer shaft is provided that rotates at the same speed and in an opposite direction to the crankshaft, and on the balancer shaft, each of the two cylinders on the back of the first to third cylinders is An independent balancer is provided at two locations corresponding to the crankshaft bearing, and a half-balanced balancer is provided at two locations corresponding to the two crankshaft bearings of the remaining one cylinder.
A balancer device for a three-cylinder engine characterized in that all of these balancers also serve as bearings.