JPS5839839A - Balancer for three-cylinder engine - Google Patents

Abstract

PURPOSE:To contrive reducing vibration of an engine and making a balancer into light-weight and compact size in such a way that it provides a balancer shaft which revolves in the inverse direction to a crankshaft, and provides balancers at three places of said shaft corresponding to the first-third cylinders, 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 of the revolving part and reciprocating part of the engine. Besides, a crank arm for the second cylinder provides the counter- weights 6b-1, 6b-2 to only the mass of the revolving parts. Further, one balancer shaft 7 is installed for revolving in the inverse direction at the same speed as the crankshaft 1 for those which have been mentioned above, the balancers 8a, 8c are installed in the zones of said shaft 7 corresponding to the bearings 9a-9c of the first and third cylinders, and a balancer 8b is installed in the zone corresponding to the second cylinder respectively. Then, the balancers 8a, 8c 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 a three-cylinder engine for an automobile, in which a counterweight is provided on the crankshaft itself, and a balancer shaft is further provided that rotates in the opposite direction at the same speed as the crankshaft.
A balancer device that balances the first-order inertia force due to the reciprocating and rotating mass of each cylinder and the first-order inertia couple around the X-axis, and also balances the first-order inertia couple in the ftj direction of the crankshaft. It's about...

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 crank weight 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 also possible to half-balance at the same position as in the case, and balance the remaining part using 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, the inertial forces of each cylinder stone are balanced as described above, and at the same time, the II couple around the X axis is also balanced, resulting in a constant couple in the b&f7r direction, and this inertial couple is balanced out and removed. In order to achieve this, conventional methods have been proposed in which the counterweight of the crankshaft has a specific separation structure as in Japanese Patent Application Laid-Open No. 55-6035, or as in Japanese Patent Publication No. 54-2333 (the inertial couple of the crankshaft system is There is one that generates a t11 force couple of the same magnitude and opposite direction on the balancer shaft to cancel it out.

The above discussion relates to the balance of inertia force and inertia couple, which is commonly used in three-cylinder engines. 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 directional inertia couple must be taken into account, and this has a large effect on engine vibration. On the other hand, the longitudinal eccentric force 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 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 inertia and inertia couple by using the counterweight of the crankshaft and the balancer of the balancer shaft. It is an object of the present invention to provide a balancer device for a three-cylinder engine which is miniaturized and can prevent inconveniences caused when a balancer shaft is immersed in oil with an advantage of bearing support.

Hereinafter, four embodiments of the present invention will be described with reference to the drawings. First, in Fig. 1, the engine system per cylinder will be explained. 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 11-inch rod, and 5 is the crankshaft. is the screw 1-, and the extension line of the crank arm 2 on the opposite side from the crank pin 3 is the total inertial force due to rotation 9!4 m, and l due to the reciprocating mass.
'lI Counterweight 6 that half balances the bamboo force
ΔQ<no. Next, a balancer shaft 7 that rotates in the opposite direction at the same speed as the crankshaft 1 is provided with a balancer 8 that half-balances the remaining part of the inertial force due to the reciprocating mass. Then, as shown in the figure, when the crank [j12 is rotated by θ around the Z-axis, the balancer shaft 1
The balun +J8 is provided so that it is located counterclockwise from the two-axis part at the same angle θ. Here, if the inertia tqw- of the reciprocating part is lp, and to make the explanation easier to understand, the equivalent emotional mass in the crank bin 3 of the rotating part is Ic, then the mass of the counterweight 6 on the crankshaft side is u and the reciprocating mass sp. For the other hand, if you do a half balance, Q is @p/2, and for the rotary quality--G, it rotates in the same direction as the crankshaft 1, so you can balance all of it, and the total becomes C. Then, (sp/2 > 10-0). Also, the quality of the balancer 8 on the balancer shaft side is the remainder of the above-mentioned damage quality.
It becomes p7/2.

By doing this, the inertial forces of the reciprocating portion and the rotating portion in the 7° 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 in this case, the total mass of the counterweights on the crankshaft side is 3.
((P, /2)ZSC), the balancer shaft side +*ii becomes (3/2)II).

Next, we will explain the balance of the mass of the reciprocating part in a three-cylinder engine with reference to Figure 2. In the figure, the first to third cylinders of J5 are indicated by suffix a, 5- or C, and the second cylinder is indicated by the upper part. At the dead center position, the first cylinder is rotated 240 degrees and the 33rd cylinder is rotated 120 degrees.

(It is θ from the state of the iron () movement 1.,: the first
Cylinder vibration J F pi, 2nd cylinder vibration J F
p2, the vibration h of the third air dot "ρ3 becomes thicker as follows.

Fl)1==ipr ω2003 (θ+240)F
p2=Illpr ω2 GOriθ Fp3−spr w2 cos (θ+120>Then, the entire inertia horn is Fpl+F p2 罎Fp3−0(゛balanced.

In addition, the length of the bamboo couple in the longitudinal direction of the crankshaft is the distance S1] where the first cylinder is to provide membrane properties.
', I decided to look at it from XP, and if I take pi/4I and 4 of each cylinder, [pi-8+Fp2(S+1 > + f-p3(S
+21 ) [- is shown.

That is, Fpl ・S ten "p2 (S + [-)
→ r−p3(S l 2 1.)6− =−5i+pr oo2 1 sin θ−−−(1
), and a longitudinal bias force around the Y axis is generated due to the reciprocating force (2) in the Z direction Ml.

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 fully balanced is shown as in FIG. weight 6
a, 6b, 6c are crank arms 2a, 2b.

It is at a position 180° phase advanced relative to 2C. Therefore, in the 7 directions when θ1'' is applied from this state, the forces F recl and F rec2 due to each counterweight mass are
, Frec3 becomes as follows.

Frcc1= (sp/2) r ω2 cos
(θ+240 +180)Frcc2- (u/2
) r cc>2 cos (θ +18
0) Frec3= (mp/2) r tn2 c
os (θ+120-t180) Therefore, the inertial force in two directions is F real + F rec2 tFrec3= 0
This balances out.

On the other hand, the inertia couple in the longitudinal direction due to forces in two directions can be found in the same way as above: 2) - (month,,'2) mLlr w2 L sin
O-.-(2a), and similarly add 1 to the long and even corners around the Y axis.

In addition, the carantauites 6a, 6b, and 6c have components not only in the Z direction but also in the Y direction, and in this Y direction, 'C'
The inertial force is balanced, and the inertia in the longitudinal direction due to the force in the Y direction is as follows.

-(f5y'2) m1Irω21 cosθ・--
(2b) That is, the horns in the Y direction cause longitudinal bias around the seven axes.

Above, the counter L on the crankshaft side is 1 to 6a to 6.
The inertia joint horns in the longitudinal direction generated by C are generated around the 7 wheels in the Z direction and around the Z axis in the Y direction, and by combining both, the 1 degree (E /2) mp
r oo21 Sinθ <5 '2 ) m1rω2
L, cosθ = (V3/'2) m1rω21 (sinθ
cos θ)...(3) By the way, the above-mentioned condition on the crankshaft side
Everyone cares! In addition to 6 cylinders for every 11 cylinders, it is also possible to separate and collect the cylinders in the first and third cylinders on both sides of the cylinder, excluding the second cylinder in the center.This case will be explained with reference to FIG. To describe the results without explaining the intermediate progress, the first and third
Cylinder counterweight Sa, 6B is (F4/2 >
(mp/2), the first cylinder's counterweight 6 is located at a position further 30° phase advanced from the position 180° phase advanced from the crank arm 2a, and the third cylinder's counterweight 6σ is from crank arm 2C 18
It is provided at a position where the phase is delayed by 30° from the position where the phase is advanced by 0°. That is, both counterweights u and 6σ are at positions that are 180 degrees anti-λ=I with respect to the crankshaft 1 and perpendicular to the central crank arm 2b.

In this case as well, the force due to each counterweight mass in two directions when it moves by θ from the state shown in the figure is 1" rec
l', ("rcc3' is Frecl' = (
f5. /2 ) (IFI/2) r ω'xco
s(θ+240 +180 +30) Frec3' =
(st/2) (ID/2) r w29-
Of course it's balanced.

Next, the longitudinal inertia couple due to this seven-sided white J is Frecl' - S + Frec3' (S L
21 ＞= (month/2) mpr ω21 sinθ
This coincides with equation (2a).

The inertia force is balanced in the Y direction as well, and the longitudinal inertia couple due to the force in the Y direction agrees with equation (2b).

From this, the Karantau 1 on the crankshaft side is very important! ! Either one for each 4' stage G cylinder, or one installed only in the 1st and 3rd cylinders, so that the cohesive IQ force is balanced and the II bamboo horns in the longitudinal direction are the same. is understood.

Above, we have explained the balance of the inertial force due to the restoring mass and the counterweight on the crankshaft, the inertia couple in the hill direction, that is, the whirling.
) formula remains, and when we synthesize this -10-, we get -)5spr oo2 L sinθ+(ffi/2
) mpr (7J2xl(sinθ−COSθ) = −(ffi/2) apr ω2 L (sin
θ−+COSθ〉...(4) Therefore, how to balance such longitudinal eccentric force on the balancer shaft side will be explained with reference to Fig. 5.First,
The balancer shaft 1 also has a balancer 8a corresponding to each cylinder.
, 8b, and 8c, the balance of each balancer 8a to 8C is Ill/2 with respect to the reciprocating mass on the crankshaft side. Further, as shown in the figure, when the second cylinder is at 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 rotated 240° counterclockwise. 18 more from the position where the phase has advanced
At a position shifted by 0°, the balancer 8C corresponding to the third cylinder is located at a position further 180° in phase from the 120° counterclockwise position.

Therefore, h F in two directions when moving by θ from this state
real, Frec2. Frec3 is F
rec1= (school p/2) r oa2
cos (θ +240 −+−180) r're
c2- (mp/2) r ω2 cos (
0+ 180) Frcc3= (mp, /2
) r ω2 cos (/7+120 amount
+80 ) and lj, the inertial force in two directions is balanced, and the longitudinal couple around the Y axis due to J in the Zh direction is (jT/2) mpr (lj2 L sinθ--
-(2a') Also, since the Y direction rotates in the opposite direction to the crankshaft, the polarity becomes negative, but the inertia saw is balanced in the same way, and the longitudinal couple around the Z axis due to this Y direction force is ( J'
T/2) mpr ω21 cosθ−-・(2b'
) Therefore, the inertia couple in the eldest direction caused by the balancers 8a to 8c on the balancer shaft side is generated around the Y axis in two directions and around the 7 wheels in the Y direction, and the composite is the above (2a') The equation and (211') give the following equation.

(f”i/2)mprω21 (sin O+ CO
S0)...(4') By the way, the balancer on the balancer shaft side can also be separated and combined in the same way as the crankshaft side in Fig. 4. To explain this case with Fig. 6, the first cylinder phase : The mass of the balancer d and the balancer corresponding to the third cylinder is 19
/2 is multiplied by /2, and the cylinder corresponding to the first cylinder is located further ahead in phase by 30 degrees, and the cylinder corresponding to the third cylinder is positioned further behind in phase by 30 degrees. 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,
This is an explanation of the inertial couple in the eldest direction, and the result is equation (4'). Therefore, this formula (4')
When combined with the above 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 is balanced by the balancer on the balancer shaft side. It will fit.

In comparison, to explain the balance due to the mass of the rotating parts of a three-cylinder engine, its configuration is the same as that shown in Fig. 2, and θ
[The force acting on the 1st to 3rd cylinder at the vertical position, F
c1. Fc2. Fc3 is as follows.

Fc1=Ilcr (Z)2 CO3(θ+240)1
3- F c2- mcr, w' cos θFc3=
=llcr oo2 cos (θ + 12
0) As a result, the longitudinal couple around the Y-axis due to the rotating mass becomes -hill mcr oo' L-sinθ -・-(5a
) The longitudinal joints around the 7th axis are 5mcr tn2 1 cos θ --・
(5b), similarly around the Y axis in two directions,
This will occur around the Z axis due to the Y direction, and when combined, the result will be as follows.

-5tacr w21 (sinθ-COSθ)---
(6) Next, the mass t of the counterweights 6a to 6C that balances this rotating mass at a ratio of 1:1 for each air n.
The balance (two) (to explain, it is the same as the configuration in Figure 3, the force due to each Karantau 1 question, [1゛0
Mouth, Frot2. Fro13 is as follows.

Frot1=tacr oo2 cos (θ+-
240+180) FroL2=IIlcr (Z
J2 COS (θ+180) [r013-11
1Cr ω2 cos (θ + 120
180) As a result, the angle J around the Y axis due to the Zh direction becomes Hrhcr ω21 sinθ
---(7a) 14- The longitudinal couple around the two axes due to the Yh direction is -Rmcr (112LCO5θ ---(
7b), and the whirling longitudinal couple, which is the combination of both, is as follows.

5 mcrω2L (sin θ-cos θ) (8) By the way, as shown in Fig. 4, also in the case of the rotational quality ■,
By multiplying the mass IC by (IN/2) and advancing or delaying the phase by 30°, it is possible to concentrate the counterweight in the first and third cylinders.

Thus, for the rotating mackerel, the combined whirling longitudinal couple around the Y and Z axes in equation (6) can be reduced to zero by combining it with the similar longitudinal couple in equation (8) by Noj Untau J-ite. As a result, the two parties will be balanced.

The present invention is based on this technical idea.
To explain a specific example using the diagram, as is clear from the above explanation, in an engine, an inertial force and a couple due to the mass of the reciprocating part and the rotating part are generated for each cylinder. Of course, it is possible to combine these qualities together and create a synergy. However, especially when it comes to the quality of the rotating parts, it is important to balance the inertial force of the crankshaft side and the joint horns. It is preferable to handle the characteristics depending on the quality of the rotating part and the balance due to the mass of the reciprocating part, which is not considered to be balanced.

At this point, counterweights 6a-1 and 6a-2 for the mass of the rotating parts for each cylinder are fitted to the crankshaft 1.
, 5b-1 and ``-2, 6c-1 and 6C-2 are installed on the opposite side C of each sink arm from the crank pin as shown in Figure 3. ShiC
, as shown in Figure 4 (1st and S cylinders excluding 2nd cylinder)
At the WA location, there are the counter counters F, i'-1, 6a-2, 6-5, and 6-2 with the same numbers. Since the masses of the parts are balanced separately, balancers 8a, 8b, 8c are used to balance only the unbalanced quality of the reciprocating parts, as shown in FIG. In the cylinder-equivalent parts of the second and third air bearings, both of them are provided with bearings in the parts corresponding to the crankshaft bearings.

In this configuration, considering the balance on the crankshaft side, the counterweight U-1 and e for the mass of the reciprocating part are
For a-2, 6c'-1 and 6σ-2, 1111 parts are concentrated in 211 places, so the mass on each cylinder side is (Illll/'2) multiplied by (5/2), and the 30° phase is calculated. If adjusted, Q<2 If the pitch of each cylinder is L as in Figure 2, for the longitudinal couple, (ap, '2) (IT/2) x2 L
= <ffi/2) It is sufficient to generate a mountain pass.

41-), counterweight u -1, synthetic material ij + M ca' of 6a'-2, 1j counterweight 6(
'-1. The synthetic mass of Iligo-2 is fy'j cc'
Then, considering the balance of the inertial force on the crankshaft 1, hold M Ga' - M CC', and set the resultant center of gravity position of the counterweight sa'-4 and -2 with respect to the Y axis as l
+x', and if the combined center of gravity position of the counter weights ec-1 and 6-2 with respect to the Y axis is L+V', then Mca'
(L+ X' (L+ y') = <5/
Since it is sufficient to satisfy 21 pL, the following general formula is obtained.

17- Mca' = Mcc' - (j'T/2)mp
L, (21+-X' + y') -
・-(9a>Next, counterweights against u- of the rotating part -6a-1 and 6a-2, 6b-1 and 6b-2, 6
For cm4 and 6, the respective synthetic materials are Mc
Assuming that a, Mcb, and MCC, then Mca=Mcb=Mcc is maintained in consideration of the balance of the inertia horn of the crankshaft 1.

In addition, the counterweights 61+-1 and 6b- of the second cylinder
Calantau 1l of the first Qi quotient relative to the composite center of gravity of 2
If the combined center of gravity position of -6a-1 and 68-2 is LLX, and the combined Φ right position of the counter weight tro G-1 and 6C-2 of the third Kizono is L + y, then Mca (L i x ) Mcc (L + y ) holds x=y.

For the longitudinal couple, take out the y b IIIJ component and calculate C1 (Mca (1, -+
) ) CO530-Month IOL It is sufficient to satisfy the following general formula.

Mca=Mcb=Mcc mcL/ (1-+ x
)18- ・ ・ ・ (9b) Therefore, each counterweight *si can be arbitrarily determined in relation to the resultant center of gravity position 1, and in both cases, the values of the resultant center of gravity positions x', y', x, and y are increased. The further away you go, the smaller the mass will be. To make it easier to understand here,
By making the center of gravity of the first and third cylinders match, and by making the center of gravity of the second cylinder match the center, X' = V'
=
'j/4)mp, and the counterweight mass at the three locations of the first to third cylinders relative to the mass of the rotating part is Kasumi C.

Further, in the first and third cylinders, the image quality (2) of the tI* portion and the rotating portion are set separately at an angle of 30', but in reality, a single number is set by vector synthesis of these.

Next, the balancer shaft 7 balances the reciprocating mass of the engine by 4 for each cylinder equivalent part.
It is sufficient to half-balance the quality of -p7·'2 in each cylinder equivalent part. Therefore, balancers '8a, 8b, 8
Let the respective masses of c be Mba, Mbb, and Mbc, and let the positions of the centers of gravity of the balancers 8a and 8c with respect to the central balancer 8b be l+x'' and LtV''. Considering the balance of the inertial force on the balancer axis, 1ba-=Mb
l+== M be.

Holding X″y″, and taking the Y-direction components of the balancers 8a and 8c corresponding to the first and third cylinders for the longitudinal couple, (Mba(1+x″) to Mbc(1+
y ″ ) ) CO330-(JT/2
)Ill)L, and the following general formula is obtained.

Mba=Mbb=Mbc=mpL/2(1,-4x
″)... ([l) Therefore, it is not necessary to align the center balancer 8b with the center of the second cylinder, but instead select the bearing 9b on the first cylinder side that corresponds to the second cylinder. , the balancer 88
corresponds to the bearing 9a on the first cylinder side, and the balancer 8G corresponds to the bearing 9C on the third cylinder side.
A, 8b, 8c may be entirely moved to the first cylinder side and arranged in a portion corresponding to the bearings 9a, 9b, 9c. Conversely, balancers 8a, 8b, and 8c are
It is also possible to move the bearings 11514M and place them in corresponding parts of the bearings 9b, 9c, and 9d, and such arrangement III
Due to this structure, the space of the bearing portion of all the balancers 8a, 8b, and 8c can be effectively utilized.

In this way, on the crankshaft 1, the first and third cylinders (9a
) counterweight 65-1 of the resultant mass of the equation and ea −
2. Connect eC'-1 and 6-2 to the crank arm 2b of the second cylinder.
counterweights 6a-1 and 6a-2, 6cm1 and 6C-2 of the combined mass of the formula (9b) are installed in the first to third cylinders at positions perpendicular to the crank pin of each crank arm Set in position 6. In addition, the balancer shaft 7
Then, balancers 8a, 8b, 8c of the mass of the formula (10) are provided at the positions corresponding to the crankshaft bearings 9a, 9b, 9c or 911, 9C, 9d on each cylinder side for half-balancing. gI of the reciprocating and rotating parts of a cylinder engine! -The inertial force and couple are balanced.

In addition, all of the balancers 8a, 8b, and 8c have historically been configured to serve as bearings.
The balancer 8a is built into a shaft tube 20 having a circumferential shape centered around the balancer shaft 7, and this shaft tube 20 is fitted into a shaft support 22 which is common to the bearing 9a through a metal 2121-.
J is done. In addition, baluns It8L+ and 8cb are constructed in the same way (shaft support 24 common to bearing 9b. Bearing 9cJ:
The balancer shaft 7 is assembled to the bearing part 25 of JL 4), so that the balancer shaft 7 is connected to the rotating part at three places at both ends and in the middle by the bearing 23 that holds these balancers 8a, ab, 8c inside.
This means that there is no need to install any other bearings.

In addition, the balancers 8a and 8c, which also serve as bearings, are placed in the bearing equivalent part of each cylinder of the crankshaft 1, which is shifted from the counter weight position, and are structured so that they do not interfere with the small counterweight of C1, which has a small turning radius. C. Balancer 8a
Take into account 8C and balancer shaft 7 itself without interfering with the counterway i and the range C near the crankshaft 1 side
J The arrangement becomes I11.

In this embodiment, the balancers 8a to 8C are moved to the first cylinder side, but the balancers 8a to 8C may be moved to the third cylinder side and placed in corresponding parts of the crankshaft bearings 9b, 9c, and 9d. Of course, this is a good thing, but in this case, the advantage of shortening the axial length of the balancer shaft 7 as in this embodiment is not eliminated.

22- As is clear from the explanation below, according to the present invention, vibrations etc. are greatly reduced by performing the following. (1) The trade-off between the arrogant part and the rotating part is treated as 6). In particular, the part due to the rotating mass is balanced by the counterweight of each cylinder of the crankshaft. . The counterweight due to the reciprocating mass is designed to be mutually limited only to the first and third cylinders on the crankshaft 1.
Therefore, the mass of the entire counterweight can be reduced compared to the case where the counterweight is provided for each cylinder. By adding generality to the installation of the counterweight and balancer, the degree of freedom in the installation 81 increases. All the balancers 8a, 8b, and 8c are arranged in the part corresponding to the bearings on the balancer shaft 1, and the balancer shaft 1 is
By bringing C closer to the crankshaft 1 side, it is possible to downsize C.

Furthermore, since the balancers 8a, 8b, and 8c have built-in bearings and also serve as bearings for the balancer shaft 7, the bending moment generated on the balancer shaft 1 is reduced.
It is possible to make the balancer device thinner in terms of strength, and the reliability is also high. The bearings of the balancer shaft 1 are connected to the crankshaft bearings 9a and 9b.
, 9c, or 911.9C, 9d, the number is installed on the bearing equivalent part, which is a highly rigid part of the engine.
Problems caused by elastic vibration of the engine due to repeated loads can be prevented. Furthermore, due to the mounting position of the engine, the smell of the balancer shaft 7 being partially submerged in the oil is reduced because the balancers 8a, 8b, and 8c are housed in the shaft tube 2o, which has a circumferential shape. It is possible to prevent an increase in resistance due to oil agitation, noise, etc.

In addition, to explain a specific example of the balancer shaft fJl with reference to FIG.
is mounted on the loading platform 16 with a limited height (at a considerable inclination of 1 from the center of gravity), such as this? & engine body 10
17 creep 11 on top, vaporizer 12 and inhalation i! 1
3 intake system, cooler/relli 14. AC015 etc. are arranged. Therefore, the upper part of the resin main body 10 is limited by the above-mentioned auxiliary machines. The balancer shaft 1 is located below the crankshaft 1 and is partially submerged in the oil.
In such a case, the effects of the present invention described above are exhibited.

[Brief explanation of drawings]

FIGS. 1 to 6 are explanatory diagrams showing detailed explanations of the present invention;
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, 2a, 2b, 2c River crank arm, 6a-4, 6a-2, sb-, eb-, , 6c
m1.6cm2. e-f-t, 6a'-2゜6σ-
1, 6 B 2... Counter weight, 1-... Balancer shaft, 8a, 8b, 8c... Balancer, 20.
...Axis tube, 21...Metal, 22, 24.25...
Axial support, 23...bearing. 25-

Claims (1)

[Claims] A crankshaft system in which crank arms are sequentially arranged at equal intervals of 120 degrees, the first and third cylinders have counterweights for the engine's reciprocating and rotating mass, and the second cylinder only has a counterweight for the engine's rotating mass. A balancer shaft is provided that rotates in the opposite direction at the same speed as the above-mentioned crankshaft. A balancer device for a three-cylinder engine, characterized in that balancers of a predetermined mass are provided so as to be half-balanced, and all of the balancers also serve as bearings.