JPH022500B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention provides a three-cylinder engine for an automobile.
A counterweight is provided on the crankshaft itself, and a balancer shaft that rotates in the opposite direction at the same speed as the crankshaft is also provided, and the primary inertia due to the reciprocating and rotating mass of each cylinder and the primary inertia around the X axis are The present invention relates to a balancer device that balances the couple and also balances the primary inertia couple in the longitudinal direction of the crankshaft.

[Conventional technology]

In each cylinder, there is an inertia force due to the reciprocating mass and a rotating mass.The inertia force due to the rotating mass can be balanced out by installing a counterweight on the opposite side of the crank arm.The inertia force due to the reciprocating mass is due to the rotating mass. The balance can be half balanced at the same position as the crankshaft, and the remaining part can be balanced by a balancer shaft that rotates in the opposite direction at the same speed as the crankshaft. By the way, in the case of a three-cylinder engine, the inertial force of each cylinder is balanced as described above, and at the same time
Even if the inertia couple around the shaft is balanced, an inertia couple occurs in the longitudinal direction, and in order to balance and eliminate this inertia couple, a counterweight of the crankshaft has been conventionally used, as in Japanese Patent Application Laid-Open No. 55-6035. There are those that have a specific separation structure, or those that generate an inertia couple on the balancer shaft that has the same magnitude and opposite direction as the inertia couple of the crankshaft system, as in Japanese Patent Publication No. 54-2333. .

[Problem to be solved by the invention]

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 point-symmetrically on both sides of the middle second cylinder.
The resulting inertia couple in the longitudinal direction of the crankshaft must be taken into account, 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 a 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 itself, the structure of the balancer shaft itself, the degree of freedom in design,
This is very advantageous in terms of the arrangement relative to the crankshaft. 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 aims to make the balancer shaft closer to the crankshaft side and to reduce its weight and size. A further object of the present invention is to provide a balancer device for a three-cylinder engine that can deal with problems caused by the balancer shaft being immersed in oil.

[Means to solve the problem]

In order to achieve the above object, the present invention provides equal counterweights for the reciprocating and rotating mass of the engine in the first to third cylinders of a crankshaft in which crank arms are sequentially arranged at equal intervals of 120 degrees,
A balancer shaft is provided that rotates in the opposite direction at the same speed as the crankshaft, and the balancer shaft has two bearing-equivalent parts on the first cylinder side and two bearing-equivalent parts on the third cylinder side. The structure is such that two phases each are provided.

【Example】

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings. First, to explain the balance system per cylinder in Fig. 1, in the figure, numeral 1 is the crankshaft, 2 is the crank arm arranged at equal intervals of 120 degrees, 3 is the crank pin, 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 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. Further, one balancer shaft 7 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 remainder of the inertial force due to the reciprocating mass. Then, as shown in the diagram, crank arm 2 is
When the balancer shaft 7 is positioned clockwise by θ from the top of the shaft, the balancer 8 of the balancer shaft 7 is positioned counterclockwise by the same amount θ from the bottom of the Z-axis. Here, the inertial mass of the reciprocating part is mp, and to make the explanation easier to understand, the equivalent inertial mass of the crank pin 3 of the rotating part is mc.
Then, the mass of the counterweight 6 on the crankshaft side should be half-balanced with respect to the reciprocating mass mp, so it is mp/2, and the mass of the counterweight 6 on the crankshaft side is mp/2, since it rotates in the same direction as the crankshaft 1 with respect to the rotating mass MC. can be balanced and become mc, and the total becomes (mp/2) + mc. Further, the mass of the balancer 8 on the balancer shaft side becomes the remainder of the above-mentioned reciprocating mass and becomes mp/2. By doing this, the Z of the reciprocating part and the rotating part,
The inertial forces in the Y direction are all 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 {(mp/2) +
mc}, the total balancer mass 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 Figure 2.
In the figure, the first to third cylinders are indicated by suffixes a to c, and the second cylinder is at top dead center, the first cylinder is rotated 240 degrees from it, and the third cylinder is at the top dead center.
The cylinder is rotated 120 degrees. Therefore, when the cylinder moves by θ from this state, the excitation force Fp1 of the first cylinder, the excitation force Fp2 of the second cylinder, and the excitation force Fp3 of the third cylinder are as follows. Fp1=mprω ² cos (θ+240°) Fp2=mprω ² cosθ Fp3=mprω ² cos (θ+120°) Therefore, the total inertial force is balanced by Fp1+Fp2+Fp3=0. In addition, in order to maintain generality, the inertia couple in the longitudinal direction of the crankshaft will be viewed from a point P that is a certain distance S from the first cylinder, and if the pitch of each cylinder is L, then Fp1.S + Fp2 (S + L) It is indicated by +Fp3(S+2L). That is, Fp1·S+Fp2(S+L)+Fp3(S+2L)=−√3mprω ² Lsinθ (1) A longitudinal couple is generated around the Y-axis due to the reciprocating mass which is the Z-direction load. To explain the balance by mass of the counterweights 6a, 6b, and 6c that are half-balanced for each cylinder in FIG. 3, as in FIG.
A case is shown in which the cylinders are at top dead center, and at this time the counterweights 6a, 6b, 6c of each cylinder are at a position 180 degrees ahead of the crank arms 2a, 2b, 2c in phase. Therefore, in the Z direction when moving by θ from this state, the forces Frec1, Frec2, and Frec3 due to each counterweight mass are as follows. Frec1 = (mp/2) rω ² cos (θ + 240° + 180°) Frec2 = (mp/2) rω ² cos (θ + 180°) Frec3 = (mp/2) rω ² cos (θ + 120° + 180°) Therefore, The inertial force in the Z direction is balanced as Frec1+Frec2+Frec3=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, Frec1・S+Frec2(S+L) +Frec3(S+2L)=(√3/2)mprω ² Lsinθ ……(2a ), which similarly produces a longitudinal couple around the Y axis. Also, the counterweights 6a, 6b, 6c are Z
It has a component not only in the 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. −(√3/2) mprω ² Lcosθ (2b) That is, a longitudinal couple around the Z axis is generated due to the force in the Y direction. As described above, the inertia couple in the longitudinal direction generated by the counterweights 6a to 6c on the crankshaft side is Z
It occurs around the Y-axis depending on the direction and around the Z-axis depending on the Y direction, and the combination of both is as follows. (√3/2) mprω ² Lsinθ− (√3/2) mpr ×ω ² Lcosθ = (√3/2) mprω ² L(sinθ-cosθ) ...(3) Above, the reciprocating mass and counter at the crankshaft We have explained the balance of inertia force by weight, longitudinal inertia couple, or whirling, but here
The longitudinal couple of equations (1) and (3) remains, and when they are combined, −√3mprω ² Lsinθ+(√3/2)mprω ² ×L(sinθ-cosθ)=−(√3/ 2) mprω ² L(sinθ+cosθ) ...(4). Therefore, how to balance such a longitudinal couple on the balancer shaft side will be explained with reference to FIG. 4. First, if the balancer shaft 7 is also half-balanced with balancers 8a, 8b, and 8c corresponding to each cylinder, 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 8a corresponding to the first cylinder is at the opposite position.
The balancer 8c corresponding to the third cylinder is located at a position further 180 degrees further out of phase from the position at which the phase has advanced 240 degrees counterclockwise, and the balancer 8c corresponding to the third cylinder is at a position further 180 degrees phase advanced from the position 120 degrees counterclockwise. Therefore, the Z-direction forces Frec1, Frec2, and Frec3 when moving by θ from this state are Frec1=(mp/2)rω ² cos(θ+240°+180°) Frec2=(mp/2)rω ² cos (θ+180°) Frec3=(mp/2)rω ² cos(θ+120°+180°), so the Z direction inertial force is balanced, and the longitudinal couple around the Y axis due to this Z direction force is , (√3/2) mprω ² Lsinθ ...(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, and the force in the Y direction The longitudinal couple around the Z-axis is (√3/2) mprω ² Lcosθ ...(2b') Therefore, the balancers 8a to 8c on the balancer shaft side
The inertia couple in the longitudinal direction caused by is also generated around the Y axis due to the Z direction and around the Z axis due to the Y direction,
The synthesized product is as follows using the above formulas 2a' and 2b'. (√3/2) mprω ² L(Sinθ+cosθ) ……(4′) By the way, in addition to installing the balancer on the balancer shaft side for each cylinder equivalent, the balancer on both sides except for the second cylinder in the center It is also possible to separately provide them in the parts corresponding to the first and third cylinders, and this case will be explained with reference to FIG. To state the results without explaining the intermediate steps, the mass of the balancers 8a' and 8c' corresponding to the first and third cylinders is (mp/2) (√3/2)
The balancer 8a' corresponding to the first cylinder is even more balanced than the above-mentioned half-balanced one.
The balancer 8c' corresponding to the third cylinder is positioned 30 degrees ahead in phase, and conversely, the balancer 8c' is positioned 30 degrees behind in phase. That is,
Both balancers 8a' and 8c' are provided at positions perpendicular to the crank arm 2b of the central second cylinder. In this case as well, the Z-direction forces Frec1′ and Frec3′ when moving by θ from the state shown in the figure are Frec1′=(√3/2)(mp/2)rω ² ×cos(θ+240°+180゜+30゜) Frec3′＝(√３／２）(mp/2)rω ² ×cos(θ+120゜+180゜-30゜) Therefore, this Z direction inertia force is Frec1′＋Frec3′ Balanced at =0. Next, the longitudinal couple around the Y-axis due to the force in the Z direction is Frec1'·S+Frec3'(S+2L) = (√3/2) mprω ² Lsinθ, which coincides with equation (2a'). On the other hand, in the Y direction, the polarity becomes negative and cos becomes sin, and the inertia forces are balanced, and the longitudinal inertia couple around the Z axis due to the force in the Y direction matches equation (2b'). From this, the inertia force is also balanced by the two balancers 8a' and 8c' provided in the parts corresponding to the first and third cylinders, and the inertia couple in the longitudinal direction is half, consistent with equation (4'). You can replace it with the same result as in the balance case. The above is an explanation of the balance of inertial force by the balancer on the balancer shaft side and the inertial 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 due to the mass of the rotating parts of a three-cylinder engine. Its configuration is the same as shown in Figure 2, and the forces acting on the first to third cylinders, Fc1, Fc2, and Fc3 at the position moved by θ, are It will look like this: Fc1=mcrω ² cos (θ+240°) Fc2=mcrω ² cosθ Fc3=mcrω ² cos (θ+120°) As a result, the longitudinal couple around the Y-axis due to the rotating mass is −√3mcrω ² Lsinθ ……(5a) Around the Z-axis The longitudinal couple becomes √3mcrω ² Lcosθ (5b), which similarly occurs around the Y axis due to the Z direction and around the Z axis due to the Y direction, and when combined, it becomes as follows. -√3mcrω ² L(sinθ-cosθ) ...(6) Next, we will explain the balance by the mass of the counterweights 6a to 6c that balances this rotating mass in a 1:1 ratio for each cylinder. The forces due to each counterweight mass, Frot1, Frot2, Frot3 are as follows. Frot1=mcrω ² cos(θ+240°+180°) Frot2=mcrω ² cos(θ+180°) Frot3=mcrω ² cos(θ+120°+180°) As a result, the longitudinal axis around the Y axis in the Z direction The couple is √3mcrω ² Lsinθ ……(7a) The longitudinal couple around the Z axis due to the Y direction is −√3mcrω ² Lcosθ ……(7b), and the combined whirling of both is as follows. . √3mcrω ² L(sinθ-cosθ) ...(8) Thus, regarding the rotating mass, the Y axis and Z of equation (6)
When the resultant whirling longitudinal couple around the axis is combined with the similar longitudinal couple of equation (8) caused by the counterweight, it becomes zero, and the two become balanced. The present invention is based on such a technical idea, and a specific embodiment thereof will be explained with reference to FIG. Therefore, in the crankshaft 1, the counterweights 6a-1 and 6a-2, 6b-1 and 6b- for the mass of the reciprocating and rotating parts are combined together for each cylinder.
2, 6c-1 and 6c-2 are provided on the opposite side of the crank pin of each crank arm as shown in FIG. In addition, as for the mass of the reciprocating portion of the balancer shaft 7, as shown in FIG. Two sets of balancers 8a'-1 and 8a'-2, 8c'-1 and 8c'-2 are provided at locations corresponding to 9c and 9d. In such a configuration, first considering the balance on the crankshaft side, since each cylinder has a counterweight for the combined mass of the reciprocating and rotating parts, the counterweights 6a-1 and 6a of the first cylinder -2, the respective combined masses Mca, Mcb, and Mcc of the second cylinder counterweights 6b-1 and 6b-2 and the third cylinder counterweights 6c-1 and 6c-2 are the inertial forces on the crankshaft. Considering balance, it is sufficient to hold Mca = Mcb = Mcc, and mc + (1/2) mp. By the way, the composite center of gravity position of the counterweight in each cylinder does not need to match the center of each cylinder.
The combined center of gravity position of the first cylinder counterweight 6a-1 and 6a-2 with respect to the combined center of gravity position of -1 and 6b-2 is L×x, and the combined center of gravity position of the third cylinder counterweight 6
If the combined center of gravity position of c-1 and 6c-2 is L+y, then x=y is maintained since Mca(L+x)=Mcc(L+y). For the longitudinal couple, it is sufficient to take out the Y-direction component and satisfy {Mca(L+x)+Mcc(L+y)}cos30° = {mc+(1/2)mp}√3L, The general formula is as follows. Mca=Mcb=Mcc={mc+(1/2)mp] L/(L+x)...(9) With this, the counterweight composite center of gravity position of each cylinder is made to coincide with its center, and x=y When = 0, the combined mass of each counterweight becomes mc + (1/2) mp as described above, but it can be arbitrarily determined in relation to the position of the combined center of gravity. That is,
As the values of x and y are increased and the combined center of gravity positions are moved away from each other, the mass can be made smaller than the above-mentioned value. Next, as is clear from the above explanation, the balancer shaft 7 is concerned only with the mass of the reciprocating part of the engine, and when it is separated and concentrated on the first and third cylinder sides, the mass of the part corresponding to the reformed cylinder is ( mp/2)
All you have to do is multiply by (√3/2) and adjust the phase by 30 degrees, and just create a longitudinal couple of (mp/2)(√3/2)2L=(√3/2)mpL. become. Therefore, if the combined mass of balancers 8a'-1 and 8a'-2 is Mba', and the combined mass of balancers 8c'-1 and 8c'-2 is Mbc', then considering the balance of inertial forces on the balancer axis, Hold Mba' = Mbc', and set the combined center of gravity position of balancers 8a'-1 and 8a'-2 to L+
x′, and the combined center of gravity of balancers 8c′-1 and 8c′-2 is L+y′, then it is sufficient to satisfy the relationship Mba′(L+x′+L+y′)=(√3/2)mpL. , becomes the following general formula. Mba'=Mbc'=(√3/2)mpL/(2L+x'+y')...(10) Therefore, even with this balancer shaft 7, the resultant center of gravity position of two balancers each provided with two balancers is The mass of the balancer can be determined arbitrarily based on the relationship, and the balancer mass can be kept small by moving the combined center of gravity positions away from each other. From this, in the crankshaft 1, the counterweight 6a of the combined mass of equation (9) is applied to the first to third cylinders.
-1 and 6a-2, 6b-1 and 6b-2, 6c-1
and 6c-2 are provided on the opposite side of the crank pin of each crank arm. Also, in the balancer shaft 7, the first
And a balancer 8 of the combined mass of formula (10) is installed at each corresponding portion of the two bearings 9a and 9b, 9c and 9d on the third cylinder side.
a'-1 and 8a'-2, 8c'-1 and 8c'-2,
It is provided at a position perpendicular to the crank arm of the cylinder, thereby balancing the inertia force due to the mass of the reciprocating part and rotating part in a three-cylinder engine and the unbalanced couple. A total of four balancers 8a'-1, 8a'-2, 8c'-1 are provided in two sets of two balancers each.
and 8c'-2 are arranged in corresponding portions of the bearings 9a to 9d that are shifted from the counterweight position in each cylinder of the crankshaft 1, and are configured so that they do not interfere with the counterweight. It is possible to arrange it close to the crankshaft 1 side without interfering with the counterweight.

【Effect of the invention】

As is clear from the above description, according to the present invention, in a three-cylinder engine, vibrations and the like are greatly reduced by balancing the primary inertial force and the inertial couple. On the crankshaft 1, the counterweights 6a-1, 6a-2, 6 are applied equally to each cylinder.
Since b-1 and 6b-2 and 6c-1 and 6c-2 are provided, a bending moment is less likely to occur in the crankshaft 1 itself, which is advantageous in terms of strength and against elastic vibration. Since generality is added to the mounting of the counterweight and balancer, the degree of freedom in design is increased. In the balancer shaft 7, the balancers 8a'-1 and 8a'-2, and 8c'-1 and 8c'-2 are all arranged in the part corresponding to the crankshaft bearing, so the balancer shaft can be effectively utilized by using the space of the bearing part. 7 can be brought closer to the crankshaft 1, contributing to miniaturization. Furthermore, by distributing the balancer mass into two sets of two, the balancers can be installed without any shortage. Note that a specific example of mounting the balancer shaft will be explained with reference to FIGS. 7 and 8. The one in Figure 7 is R-
This is a case where the engine is installed under the loading platform in the R type, and the engine body 10 is mounted approximately horizontally, and the air cleaner 11, carburetor 12, and intake pipe 13 are installed horizontally just above the middle of the engine body 10. Cooler compressor 1
4. Alternator (ACG) 15 etc. can also be installed.
Therefore, if the balancer shaft 7 is placed above so as not to be submerged in oil, it will interfere with the carburetor 12, alternator (ACG) 15, etc., and being able to move it closer to the crankshaft 1 will prevent such interference. Being able to avoid it gives you an advantage. The one in FIG. 8 is of the F-F type, in which the engine body 10 is mounted almost vertically, and the air cleaner 11,
A carburetor 12 and an intake pipe 13 are provided on the passenger compartment side,
The exhaust pipe 16 is provided on the front panel side, and if the balancer shaft 7 is placed in front of the engine body 10, it will interfere with the catalytic converter 17 of the exhaust pipe 16. Therefore, in this case as well, if the balancer shaft 7 can be moved closer to the crankshaft 1, interference with the contact converter 17 and the like can be avoided, and the engine body 10 can be moved closer to the front panel to make the vehicle interior larger. etc., various effects can be obtained.

[Brief explanation of drawings]

1 to 5 are explanatory diagrams for explaining the principle of the present invention, FIG. 6 is a schematic diagram showing an embodiment of a balancer device for a three-cylinder engine according to the present invention, and FIGS. 7 and 8 are diagrams according to the present invention. FIG. 2 is a side view showing a specific example of the case where the method is applied to an automobile engine. 1...Crankshaft, 2a, 2b, 2c...Crank arm, 6a-1, 6a-2, 6b-2, 6c-
1, 6c-2... Counterweight, 7... Balancer shaft, 8a'-1, 8a'-2, 8c'-1, 8c'-
2... Balancer, 9a, 9b, 9c, 9d... Crankshaft bearing.

Claims (1)

[Claims] 1. Counterweights for the reciprocating and rotating mass of the engine are provided equally in the first to third cylinders of the crankshaft, in which the crank arms are sequentially arranged at equal intervals of 120 degrees, and the crankshaft is arranged at the same speed in the opposite direction with respect to the above crankshaft. A balancer shaft is provided, and two balancers are installed on two bearing-equivalent parts on the first cylinder side and two bearing-equivalent parts on the third cylinder side of the balancer shaft.
A balancer device for a three-cylinder engine, characterized in that it is assembled.