JPS5839853A - Balancer for three-cylinder engine - Google Patents

Abstract

PURPOSE:To lighten and make small in size a balancer by disposing each of independent balancers on a positions, corresponding to bearings of the first and third cylinders, of a balancing shaft which revolves in the direction opposite to a crank shaft, by also disposing a balancer split in two pieces on the position of said balancing shaft corresponding to a bearing of the second cylinder, and by also using all of said balancers as bearings. CONSTITUTION:Counterweights 6a-1, 6a-2; 6c-1, 6c-2 and 6a'-1, 6a'-2; 6c'-1, 6c'-2 for the mass of a reciprocating portion and a revolving portion of an engine, are disposed on crank arms of the first and third cylinders of a crank shaft 1. Counterweights 6b-1, 6b-2 only for the mass of a reciprocating portion of said engine are also disposed on a crank arm of the second cylinder. Further, a balancing shaft 7 is placed, which rotates in the opposite direction to and at the same speed as said crank shaft 1. Balancers 8a, 8c are disposed on the positions corresponding to bearings 9a, 9d of said first and third cylinders and balancers 8b-1, 8b-2 split in two pieces are also disposed on the position corresponding to bearings 9b, 9c of said second cylinder. All of said balancers 8a to 8c are supported in shaft tubes of cylindrical shape and are also used as bearings 23.

Description

Detailed Description of the Invention The present invention provides a three-cylinder automatic heavy-duty 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 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 at the same position as when using the crankshaft, 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 three-cylinder engine, the inertia forces of each cylinder are balanced as described above, and at the same time, even if the inertia couple around the X axis is also balanced, an inertia couple in the longitudinal direction occurs, and this inertia couple must be balanced and removed. In order to do this, conventionally, for example, the counterweight of the crankshaft has a specific separation structure as in Japanese Patent Application Laid-open No. 55-6035, or the inertial couple of the crankshaft system as in Japanese Patent Publication No. 54-2333. There is one that generates an inertia couple on the balancer shaft that has the same but opposite directions 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 inertia couple must be taken into consideration, 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 By specifying the mounting position of the balancer, you can determine the structure of the balancer shaft itself, the degree of freedom in design, and the arrangement with respect to the crankshaft.
This will be very advantageous in terms of etc.

In view of these circumstances, the present invention achieves balance against the inertial force and inertial couple by using the counterweight of the crankshaft and the balancer of the balancer shaft, and also brings the balancer shaft closer to the crankshaft side. It is an object of the present invention to provide a balancer device for a three-cylinder engine which is advantageous for supporting bearings and prevents inconveniences when the 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 pin, 4 is the crank rod, and 5 is the crankshaft. It is a piston, and a counterweight 6 is provided on the extension line of the crank arm 2 on the opposite side from the crank pin 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 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 mass after tl. As shown in the figure, when the crank arm 2 is positioned clockwise by θ from the top of the Z-axis, the balancer 8 of the bouncer shaft 1 is positioned counterclockwise by the same amount θ from the bottom of the Z-axis. Here, if the inertial mass of the reciprocating part is -0, and to make the explanation easier to understand, the equivalent inertial mass of the crank pin 3 in the zero rotation part is Ic, then the mass of the counterweight 6 on the coolant shaft side is relative to the reciprocating mass 1p. If so, half balance is fine.■
p/2, rotating mass -0 rotates in the same direction as crankshaft 1, so all of it can be balanced -
0, and the sum becomes (II)/2)+anal. 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 are all balanced. Therefore 3
In a cylinder engine, if a counterweight 6 and a balancer 8 of the above-mentioned masses are attached to each cylinder equivalent 1, then the total mass of the counterweights on the crankshaft side is 3 ((+ep/2)+-C). , the total mass of the balancer on the balancer shaft side is (3/2)u.

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 c,
Also, the second cylinder is at top dead center, and the first cylinder is at the top dead center.
The cylinder is rotated by 40 degrees, and the third cylinder is rotated by 120''.

Therefore, when the cylinder moves by θ from this state, the excitation force F91 of the first cylinder, the excitation force Fp2 of the second cylinder, and the excitation force FD3 of the third cylinder are as follows.

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

In addition, in order to give the inertia couple in the longitudinal direction of the crankshaft, it is viewed from a point P that is a distance S apart from the first cylinder in order to have a -membrane property, and if the pitch of each cylinder is L, then Fpl・S+Fp2(S+1>+Fp3(S+21>6
− is indicated.

That is, Fll・S0Fl)2(S+1>10Fl)3(S+2
L)=-j"japr (1) 2 1 sin θ-
--(1), and the reciprocating mass, which is the Z-direction load, causes a longitudinal bias around the seven wheels.

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. counter weight 6
a, 6b, 6c are crank arms 2a, 2b.

It is located at a position 180° in phase with respect to 2G. Therefore, in the two directions when moving by θ from this state, the forces due to each counterweight mass Frecl, Frec2, Fr
ec3 becomes as follows.

Frecl= (sp/2) r ω2
cos (θ +240 +180) Frec2=
(lp/2) r ω2 CO6(θ
+180)'Frec3= (mp/2) r
ω2 cos (θ +120 +180
) Therefore, the inertial force in the Z direction is F recl + F rec2+ F rec3=
0 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, F recl −S + F rec2 (S + 1
) 10F rec3 (S +21) = (Jj/2) apr ω21 sinθ---
(2a), and similarly a longitudinal bias force around the Y axis is generated.

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. .

−(Jj/2) spr oo2 L cosθ−−
-(2b) That is, a longitudinal bias force around the Z axis is generated due to the force in the Y direction.

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

(HI3 > II) r w2 1-sin θ
−(ffi/2) aprXω2Lcosθ = (ffi/2) iprω2 1 (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 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 without explaining the intermediate steps, the counterweights 6j and 6σ of the first and third cylinders are (J'N/2) (
lp/2), the counterweight side of the first cylinder is at a position further 30° phase advanced from the position 180° phase advanced from the crank arm 2a, and the third cylinder counterweight 6d is It is provided at a position that is 30 degrees behind the position that is 180@phase ahead of the crank arm 2C.

That is, on both counterweight sides, ε is a position 180 degrees opposite to the crankshaft 1 and perpendicular to the central crank arm 2b.

゛In this case, hFrec due to the quality of each counterweight in two directions when it moves by θ from the state shown in the figure.
', l: rac3' is 9- Frecl' - (old/2) (mp/2
)r ω2xcos(θ+240 + 180 +3
0) Frec3' - (J'j/2) (sp
/2) r ω2xcos(θ+120 +
180 -30), and the inertial force in two directions becomes Frei01' + Frec3' = Q, which naturally balances out.

Next, the inertia couple in the potato direction due to the forces in these two directions is Frec1'-8+Frec3' (S+21)
−(IN/2)mpr ω2 L sin
θ, which agrees with equation (2a).

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

From this, it can be seen that even if the counterweight on the crankshaft side is provided with 11 I for each cylinder, or one each is provided only in the 1st and 3rd cylinders, the inertia force is balanced and the inertia couple in the longitudinal 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, we have explained the whirling, but now the longitudinal couple of equations (1) and (3) remains, and when they are combined, we get the old ■pr oo2 Lsin θ + (IN/
2) mpr w2xi-(sinθ-COS
θ) = −(IN/2) mpr oo21 (sin θ
+CO8θ)...(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 7 also has a balancer 8a corresponding to each cylinder.
, 8b, and 8c, the mass of each balancer 8a to 8C is mp/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 8b corresponding to the first cylinder is at the opposite position.
a is further 18' from the position where the counterclockwise rotation has advanced by 2400 phases.
The balancer 8C corresponding to the 3rd cylinder is located at the left 1
It is located at a position further 180° in phase from the position 120° around.

Therefore, the force F in two directions when moving by θ from this state
recl, Frec2. Frec3 is Frecl
-(-p/2) r oo2 cos
(θ +240 +180) Frec2- (a
p/2) r ω2 cos (θ−+−180)
F rec3- (ID/2) r ω2
cos (θ) 120 + 180), the inertia forces in two directions are balanced, and the longitudinal eccentric force around the Y axis due to the forces in these two directions is (Jj/2) apr (1)2 L sinθ−-
-(2a') Also, in the Y direction, the polarity is negative because it rotates in the opposite direction to the crankshaft, but in the same way, the inertial force is balanced,
The longitudinal couple around the seven wheels due to this force in the Y direction is (Jj/
2) giprω21cosθ...(2b') Therefore, the inertia couple in the longitudinal direction generated by the balance +j8a to 8c on the balancer axis side also occurs around the Y wheel in two directions and around the 7 wheels in the Y direction, and is the composite of these. is above (
Using equations 2a' and 2b', we obtain the following.

(j'N/2) ipr ω2 1 (si
n 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 shown in FIG. The mass of the balancer U corresponding to the cylinder and the balance rust corresponding to the third cylinder is -p/
2 multiplied by old/2, the cylinder equivalent to the first cylinder is located further ahead in phase by 30°, and the cylinder equivalent 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 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 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 a three-cylinder engine.The configuration is the same as that shown in Fig. 2, and θ
The force acting on the 1st to 13th-3rd cylinders at the position of movement, FCI, Fc2. l”c3 becomes as follows.

Fc1-icr ω2 cos (θ)24G)FC
2=ICr ω2 cos θ Fc3-mar ω2 cos (θ +120
) As a result, the longitudinal eccentric force around the Y-axis due to the rotating mass is
-j'jgicr cc>2 L sin θ
---(5a) Longitudinal eccentric force around the two axes becomes 1crω2Lcosθ (5b), and similarly occurs around the ゛・Y axis in the Z direction and around the Z wheel in the Y direction. Then, by combining □, it becomes as follows.

-Emcr ω2 L (sinθ-cosθ) --
-(6) Next, to explain the balance by the mass of the counterweights 6a to 6C that balances this rotating mass at a ratio of 1:1 for each cylinder, it is the same as the configuration shown in FIG. 3, and the force due to the mass of each counterweight, F rot
l, F rot2. F rot3 is as follows.

1” rotl-peng cr (132 cos (θ
, +240 +180) Frot2=mcro
o2 cos (θ+180)14- F rot3=*cr ω2 cos (θ+1
20 +180) As a result, the longitudinal eccentric force around the Y axis due to the Z direction is E-aroo2 L sin
θ ---(7a) The longitudinal eccentric force around the seven wheels in the Y direction is -JTscr ω21cos θ ---(7b), and the whirling that is a combination of both is as follows.

J'j-cr ω2 1 (sin θ-CO
S θ ) --(8) By the way, in the case of such a rotating mass, as shown in Figure #14, the mass is changed to me (m/2
), and by advancing or delaying the phase by 300, it is possible to separate and concentrate the counterweights on the first and third cylinders.

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

The present invention is based on such technical considerations, and its concrete implementation will be explained with reference to FIG. Inertial force and couple force are generated due to the mass of the rotating parts, and when balancing these two types of mass, there are cases where the forces are separated and concentrated on each cylinder and on the first and third cylinder sides, respectively. Like a lever to follow 2
Although it is possible to group the seed qualities together and use one type of balance method, it may be preferable to use different balance methods for each mass.

Therefore, in the crank wheel 1, first, for each outer cylinder, counterweights 6a-1 and 6a-2°6b for the mass of the reciprocating part are calculated.
-5 and 6L2, 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 rotating parts, as shown in Fig. 4, counterweights IJ-1 and m-2, and sbee 1 and 6-2 are placed at two locations on the first and third cylinders excluding the second cylinder. It is a provision. In addition, the balancer shaft 7 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. The balancers 8a, 8c, which are independent of those bearings 9a, 9d on both sides of the crankshaft 1, select the two bearings 9b, 9c on the inside of the crankshaft 1 as the part corresponding to the second cylinder. Balancer 8b-i, ab divided into two parts at those locations
-2 is provided so that all the bearings can also be used as bearings.

In such a configuration, when considering the balance on the crankshaft side, the counterweights d-s, ua, and 6('-1 and 6+'-aE) and T are separated and concentrated at two points for the mass of the rotating part. Therefore, the combined mass on each cylinder side is I
Multiply c by (IN/2) and adjust the phase by 30°. If the pitch of each cylinder is L as in Fig. 2, then for longitudinal eccentric force, -c(j'j/2) x 2L = Igo■c
It is sufficient to generate l.

Therefore, the counterweight d −x , the synthetic quality ■ of d−2 is Mca′, and the counterweight W! -1, ec'
If the combined mass of -2 is M cc', then the crank wheel °
Considering the balance of inertial force on 1, Mca' −M QC
' to hold.

In addition, the 17- composite weight 6th position 1 of the counterweight el-4 and ba-2 is L + XI, and the counterweight 6σ-
The composite center of gravity position of 1 and 6-2 on the Y axis is L+V'
Then, Mca' (1+ X' +L+ y') = Jj
Since it is sufficient to satisfy icL, the following general formula is obtained.

Mca' - Mac' = JjicL/ (2L
+ x' + y' )...(9a) Next, counterweight 6 for the mass of 5I
For a-1 and 6a-2, 6b, 4 and 6b-2, 6cm1 and 60-2, the combined mass of each is Mca,
When Mcb and MCC are taken into account, Mca - Mcb=Mccc is maintained in consideration of the balance of inertial force on the crankshaft. Also, the counterweight 6, b- of the second cylinder
The combined center of gravity position of the counterweights 6a-1 and 68-2 of the first cylinder with respect to the combined center of gravity position of 1 and 6b-2 is [+X
, if the combined center of gravity position of the third cylinder counterweights 60-1 and 60-2 is L+V, then Mca(L+x)=M
cc(L+y) holds x=y.

Then, for the longitudinal eccentric force, take out the component in the ♀ direction, -18= (Mca (L+ x) + Mcc (L+ y))
It is sufficient to satisfy cos30- (JT/2) ■pL, and the following general formula is obtained.

Mca=Mcb-Mac-(1/2) spy/
(L + x)...(9b) As mentioned above, each counterweight mass can be arbitrarily determined in relation to the composite center of gravity position, and both
, yl, x, and y, the larger the distance, the smaller the mass will be. Here, to make it easier to understand,
Counterweights 6a-1 and 6a- in the first and third cylinders
2. Match the composite center of gravity position of side-1 and side-2, counterweight 6cm1 and the composite center of gravity position of ec-2, e-1 and 1-2, and set the counterweight 6b-1 and 6b in the second cylinder. -2's composite center of gravity as the center, X' =
When y' = x-y -0, the counterweight mass at the two locations of the first and third cylinders relative to the mass of the rotating part is (old/2)sc, and the mass of the first to third cylinders relative to the quality of the reciprocating part is The counterweight masses at the three locations are (
1/2. ) -EI.

Further, although the first and third cylinders are provided separately for rotation and reciprocation, they are actually vector-combined into a single cylinder.

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

The masses of 8C are Mba and Mbc, the combined mass of the balancers 8tL1 and ab-a divided into two is Mbb, and the positions of the balancers 8a and 8c with respect to the combined center of gravity of the central balancers 8b-1 and 8b-2 are l. ＋x／／
, L +, y//, considering the balance of inertial force on the balancer axis, Mba-Mbb=Mbc x
″= y” [76° Also, for the longitudinal eccentric force, take the Y direction component of the first and third cylinder side (1) l< lancers 8a and 8c, (Mba(L+x”) +MbO( L
, + V")) cos30= (J'j/2
) It is sufficient to satisfy the relationship IpL, and the following general formula is obtained.

Mba-Mbb=Mbc=-pL/2(L+x
”)・・・・■) Therefore, even if the pitches of 9C and 9d with respect to the bearings 9a and 9b of the crankshaft 1 are different, the center balancer ab-
By selecting the combined center of gravity position of 1 and 8b-2, four balancers 8a, 8b-1, 8b-2, 8c are connected to bearings 9a, 9.
b, 9c, and 9d, and if the bearing side has the same pitch, the balancer ab-,, 8tL2
This can be easily done by dividing the mass of 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, 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 etf-i and m-2 of the combined mass of the equation
, sc-1 and 6-2 are installed in the second cylinder at positions perpendicular to the rank arm 2b, and a counterweight 6a-1 of the combined mass of formula (9b) is installed in the first to third cylinders. 6a-2, 6cm1 and 60-2 are provided on the opposite side of the crank pin of each crank arm. Further, in the balancer shaft 7, the balancers 8a and 8b are connected to bearings 9a of the first and third cylinders.
.

Balancer 8b-i, 5 divided into two parts in the part corresponding to 2l-9d
b-2 is half-balanced by the mass of the equation @) at the part corresponding to the bearings 9b and 9c of the second cylinder, and as a result, 3
The inertial force and couple due to the masses of the reciprocating and rotating parts of the cylinder engine are balanced.

Then, T f) l< 7 f8a, 8b-1
, 8b-2, and 8c are arranged in the bearing equivalent part shifted from the counterweight position of the crankshaft 1 to avoid interference with the counterweight, so the presence of the balancer shaft 7 should be taken into account. It is possible to arrange the crankshaft 1 close to the crankshaft 1 side in relation to only the counterweight.

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. The balancer corresponding to the cylinder can also be divided into two parts.

Matasarani, to t(1) t<y>su 8a, 8b-1,
8b-2゜8G is configured to also serve as a bearing, and this is used as the 8th
To explain in detail with the drawings, first, the balancer 8a is built in a shaft tube 20 having a full circumference shape centered around a balancer shaft 722-, and this shaft tube 20 is connected to a shaft support 20 common to the bearing 9a via a metal 21.
It is fitted and assembled. Also, another 3m balancer 8L
1, 8b-2, and 8c are constructed in exactly the same way, and the bearing 9b
The balancer shaft 7 is assembled to the common shaft support 24, the shaft support 25 common to the bearing 9C, and the shaft support 26 common to the bearing 9d, so that the balancer shaft 7 is assembled to the balancer 8a.

It is rotatably supported at both ends and in the middle by the bearings 23 having the above-described configuration in ab, , 8b-2, and 8c, and there is no need to provide an external bearing.

By doing so, vibrations etc. are greatly reduced. Since we ignore the mass of the moving part and the rotating part, and use different methods of balance for each, we 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 mass of the entire counterweights can be smaller than in the case where the counterweights are provided for each cylinder. Being countered increases the degree of freedom in design. Furthermore, all the balancers 8a, 8L1,
8b-2.

8C are arranged at a distance from each other in the part corresponding to the crankshaft bearing, so by effectively utilizing the space of the bearing part, it is possible to bring the balancer shaft 1 closer to the crankshaft 1, contributing to miniaturization and reducing the balancer mass. It can also be small.

In addition, Suhe T (D Hafunsa 8a, 8b-1, 8b
- Since 2 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 significantly reduced, making it possible to reduce the diameter of the balancer shaft in terms of strength. Reliability is also good. The bearings of the balancer shaft 1 are connected to the crankshaft bearings 9a, 9b, and 9c.

The provision in the portion corresponding to the bearing 9d is a location with high rigidity for the engine, and can prevent problems caused by elastic vibration of the engine due to repeated loads i.

Furthermore, even if the balancer shaft 7 is partially submerged in oil due to the mounting position of the engine, all balancers 8a
, 8L1, 8b-2, 8c are all circumferential shaft tubes 20
Since the oil is housed inside, it is possible to prevent an increase in resistance due to oil agitation, oil spraying, etc.

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
An air cleaner 11, a carburetor 12, an intake system including an intake pipe 13, a cooler compressor 14, an ACG 15, etc. are arranged on the engine body 10 in such a posture. Therefore, the engine main body 101 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 7 is located below the crankshaft 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 of the 25-cylinder engine, and Fig. 9 is a schematic diagram showing an embodiment of the balancer device for a three-cylinder engine according to the present invention. FIG. 4 is a side view of a specific example of the case. 1... Crank shaft, 2a, 2b, 2c... Crank arm, 6a-1, 6a-2, 6b-1, 6b-2, e
c-1,6cm2.61-i, &r-a. 6('-1.Elσ-2... counterweight, 7.
... Balancer shaft, 8a, 8L4, 8b-2, 8cm
...Balancer, 9a, 9b, 9c, 9d...Crankshaft bearing, 20...Shaft tube, 21...Metal, 2
2゜24, 25.26... shaft support, 23 river bearing. Patent Applicant Fuji Heavy Industries Co., Ltd. Representative Patent Attorney Jundo Kobashi Patent Attorney Susumu Murai 26-b-2 2 8s.

Claims (1)

[Claims] A counterweight for the reciprocating and rotating mass of the engine is placed on the first and third cylinders, and a counterweight for the reciprocating mass of the engine is placed on the second cylinder of the crankshaft where the crank arms are sequentially arranged at equal corners of 120°. one balancer shaft rotating in the opposite direction at the same speed with respect to the crankshaft, and one crankshaft of each of two of the first to third cylinders on the balancer shaft; Independent balancers are installed at two locations corresponding to bearings, and two separate balancers are installed at locations 211 and 211, corresponding to the two crankshaft bearings of the remaining cylinder, so that all of these balancers are equipped with bearings. A balancer device for a 3-cylinder engine that is characterized by its dual-purpose use.