JPH04224338A - Balancer device for engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an engine piston,
This invention relates to a balancer device for damping the vibrations of the engine by eliminating inertial force and inertial couple caused by connecting rods and the like.

0002

2. Description of the Related Art Conventionally, there is a balancer device for an engine of this type disclosed in, for example, US Pat. No. 3,667,317. As shown in FIGS. 7 and 8, in this balancer device, a drive gear 33 is attached to a crank arm 32 at an intermediate portion of a crankshaft 31. As shown in FIGS. Drive gear 3
3, first and second weights 34, 35 are rotatably supported, and first and second driven gears 36, 37 are attached to the weights 34, 35. and,
A first driven gear 36 is meshed with the drive gear 33, and a second driven gear 37 is meshed with the first driven gear 36.

According to the balancer device configured as described above, when the crankshaft 31 and the drive gear 33 rotate together, the rotation is sequentially transmitted to the first and second driven gears 36 and 37, and the rotation is transmitted to the first and second driven gears 36 and 37 in order. 34 and 35 rotate,
Dampen engine vibrations. Incidentally, it is desired that the balancer device be made more compact, and one possible means of achieving this is to move both weights 34 and 35 closer to the crankshaft 31.

0004

However, if the first and second weights 34, 35 are brought too close to the crankshaft 31, a problem arises in that the weights 34, 35 come into contact with the connecting rod 39 and impede its movement. . Also,
As shown by the two-dot chain line in FIG. 7, when a counterweight 38 is formed on the crank arm 32, both the weights 34 and 35 may come into contact with the counterweight 38. Therefore, in order to avoid interference with the counterweight 38 and connecting rod 39, the weights 34 and 3 are
In order to bring the weights 34, 35 closer to the crankshaft 31, the lengths of the weights 34, 35 in the axial direction (left-right direction in FIG. 7) are restricted. In addition, the drive gear 33 and both driven gears 3
When spur gears are used as the gears 6 and 37, the thickness of the gears is large, so the weights 34 and 35 are will account for an even smaller proportion. Due to such restrictions, the weights 34 and 35 end up having shapes with low weight efficiency.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide an engine in which the axial length of the weight can be increased and the weight can be shaped into a highly weight-efficient shape. The purpose of the present invention is to provide a balancer device.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention has a driving gear rotatably attached to an intermediate portion of a crankshaft, and a vibration damping weight rotatable separately from the crankshaft. In an engine balancer device, a driven gear that meshes with the driving gear is attached to the weight, and vibrations of the engine are damped by rotating the weight when the crankshaft rotates. is a helical gear.

[0007]

[Operation] When the crankshaft rotates, the rotation is transmitted to the weight via the driving gear and the driven gear. This rotation of the weight generates a load that eliminates the inertial force or inertial couple caused by the piston, connecting rod, etc., and this load reduces the vibration of the crankshaft.

By the way, in the present invention, since helical gears are used as the driving gear and the driven gear, the thickness of the gears can be smaller than that of spur gears to perform the same torque transmission, and the thickness of the weight in the axial direction can be reduced accordingly. There will be some leeway in length.

[0009]

[Example] Hereinafter, an example embodying the present invention is shown in Figs.
This will be explained according to FIG. FIG. 1 is a front view showing the arrangement of a crankshaft 1 and a balancer device 2 of a four-cylinder automobile engine. The crankshaft 1 is for extracting power by converting the reciprocating motion of the piston into rotational motion, and has first to fifth crank journals 3a to 3e, a first
- Fourth crank pins 4a to 4d, first to eighth crank arms 5a to 5h, first to eighth counterweights 6
It is composed of a to 6h, etc. The crankshaft 1 is rotatably supported by a cylinder block in the direction of arrow D in the first to fifth crank journals 3a to 3e. A crank pulley 20 is attached to the front end of the crankshaft 1, and a flywheel 21 is attached to the rear end (see FIGS. 4 to 6). Also, the first ~
A connecting rod 7 is connected to each of the fourth crank pins 4a to 4d. Note that in FIG. 1, only the lower end portion of the connecting rod 7 is shown for convenience.

A drive gear 8 is fixed coaxially with the third crank journal 3c at the front of the fifth crank arm 5e and the fifth counterweight 6e. The drive gear 8 is constituted by a helical gear whose teeth are oblique to the axis. In this embodiment, the helical gear twists in a left-handed twist (left shoulder upward). Under the conditions of the same diameter and the same thickness, helical gears have wider face width and thicker face thickness than spur gears.
This gear has characteristics such as: (1) it has a larger meshing ratio, so it has greater strength than the same spur gear, and (2) it rotates more smoothly than a spur gear, so it produces less noise when meshing.

A balancer device 2 is disposed close to and below the fourth crank arm 5d, third crank journal 3c, drive gear 8, fifth crank arm 5e, and fifth counterweight 6e. As shown in Figure 3,
The balancer case 9 of the balancer device 2 is made up of a pair of support pieces 10 and 11 that extend in the left-right direction in parallel with each other, and a pair of connection pieces 12 that connect the opposing left and right ends of both the support pieces 10 and 11. It is formed into a frame shape. The balancer case 9 is fixed to the cylinder block at its four corners with bolts (not shown).

As shown in FIG. 1, the front surface of the front support piece 10 is located on the same plane as the front surface of the fourth counterweight 6d, and the rear surface of the rear support piece 11 is located on the same plane as the front surface of the fourth counterweight 6d. It is located almost on the same plane as the rear surface of the weight 6e. Therefore, the balancer case 9 is disposed within the axial length (front-to-back length) L1 of the fourth and fifth counterweights 6d and 6e. Furthermore, in this embodiment, the thickness t1 of the front support piece 10 is set larger than the thickness t2 of the rear support piece 11.

As shown in FIG. 3, the balancer case 9 includes:
A first weight 13 and a second weight 14 are rotatably supported by a pair of fixed shafts 15. That is,
Both ends of each fixed shaft 15 are inserted and locked into a pair of left and right holes 17 provided through each of the front and rear support pieces 10 and 11, so that they cannot rotate. In addition, the first and second weights 13, 1
4 has a substantially semi-cylindrical shape, and is rotatably fitted onto the fixed shaft 15 through bearings 13a and 14a.

Furthermore, the first and second weights 13
, 14 is provided with a first gear having a diameter smaller than that of the drive gear 8.
and second driven gears 18 and 19 are externally fitted and fixed. Both driven gears 18 and 19 are rotatable on the fixed shaft 15 together with the first and second weights 13 and 14. Both the driven gears 18 and 19 are constructed of helical gears similarly to the drive gear 8. The twisting direction of the first driven gear 18 is set to the right (upward to the right), and the twisting direction of the second driven gear 19 is set to the twisting to the left (upward to the left). Then, as shown in Figure 2, the first
A driven gear 18 meshes with the drive gear 8, and a second driven gear 19 meshes with the first driven gear 18. When the gears are in mesh as described above, Figure 1
As shown in , the first and second weights 13 and 14 are arranged within the longitudinal length L2 of the third crank journal 3c.

According to the balancer device of this embodiment configured as described above, when the drive gear 8 rotates integrally with the crankshaft 1, the rotation is transmitted to the first driven gear 18 and the first weight 13 rotates on the fixed shaft 15. Further, the rotation of the first driven gear 18 is transmitted to the second driven gear 19, and the second weight 14 rotates on the fixed shaft 15. The rotation of both weights 13 and 14 generates a load that eliminates the inertial force and inertial couple caused by the piston, connecting rod 7, etc., and this load reduces the vibration of the crankshaft 1.

That is, vibrations of the crankshaft 1 include bending vibrations and torsional vibrations. Figure 4 is 450Hz
Figure 5 shows the bending vibration mode of crankshaft 1 at 2.
1 schematically shows the bending vibration of a crankshaft 1 at 00 Hz. At 450Hz, the front part of the crankshaft 1 (the left side in the figure) vibrates in the vertical direction as shown by the arrow.
At 200 Hz, the rear part of the crankshaft 1 (the right side in the figure) vibrates in the vertical direction as shown by the arrow, and in both cases it can be seen that the amplitude near the third crank journal 3c is small. Therefore, the vibration generated in the cylinder block is also small near this third crank journal 3c.

Here, for example, the drive gear 8 is attached to a portion of the crankshaft 1 where bending vibration is large, such as the front end or the rear end of the crankshaft 1, and the balancer case 9 and the first and second gears are installed near the drive gear 8. When the weights 13 and 14 are arranged, the drive gear 8 rotates while vibrating greatly. This vibration increases or decreases the backlash between the drive gear 8 and the first driven gear 18, increasing gear hitting noise and friction.

However, in this embodiment, the drive gear 8 is attached to the front part of the fifth counterweight 6e, and the first and second weights 13 and 14 are mounted within the longitudinal length L2 of the third crank journal 3c. The front and rear support pieces 10 and 11 of the balancer case 9 are arranged within the front and rear length L1 of the fourth and fifth counterweights 6d and 6e. Therefore, even if the crankshaft 1 causes bending vibration as described above, the vibration when the drive gear 8 rotates is small. Further, for the same reason, the vibration of the balancer case 9 is also reduced, so that the vibration of the first and second driven gears 18 and 19 attached to the balancer case 9 during rotation is reduced. Therefore, in particular, the center-to-center distance between the drive gear 8 and the first driven gear 18 is kept substantially constant, and increases in gear hitting noise and friction due to increases and decreases in backlash are suppressed.

Furthermore, by arranging the first and second weights 13, 14 within the longitudinal length L2 of the third crank journal 3c, both weights 13, 14
When the fourth and fifth counterweights 6d and 6e rotate,
and connecting rod 7. Therefore, the space in which each weight 13, 14 can rotate is expanded, and the radius of each weight 13, 14 can be set relatively long. In addition, in this embodiment, since helical gears are used as the driving gear 8 and both driven gears 18 and 19, the thickness of the gear is smaller than that of a spur gear to perform the same torque transmission. An allowance is made in the front and rear lengths of the weights 13 and 14. Therefore, both weights 13 and 14 can be made long in both the axial direction and the radial direction, and have a highly weight-efficient shape.

During engine operation, the crankshaft 1
causes torsional vibration in addition to bending vibration. Figure 6 shows 450
1 schematically shows the torsional vibration modes of a crankshaft 1 in Hz; From the figure, the fourth counterweight 6d
It can be seen that the amplitude θ5 of the fifth counterweight 6e portion is smaller than the amplitude θ4 of the portion. In this embodiment, the drive gear 8 is connected to the fifth counterweight 6 as described above.
Since the drive gear 8 is attached to the front part of the fourth counterweight 6d, the rotation fluctuation of the drive gear 8 is smaller than that when the drive gear 8 is attached to the front side of the fourth counterweight 6d. Therefore, it is possible to reduce the thrust sound secondarily derived between the first weight 13 and the balancer case 9 due to the gear striking sound and rotational fluctuation.

Furthermore, in this embodiment, the balancer case 9
The front support piece 10 is made thicker than the rear support piece 11 to increase rigidity. In this way, the front support piece 10
The reason for making it thick is as follows. That is, in this embodiment, the first and second weights 13 and 14 are arranged within the longitudinal length L2 of the third crank journal 3c, and the fourth and fifth counterweights 6d and 6e are arranged within the longitudinal length L1. Since the structure is such that the balancer case 9 is disposed at both sides, the thickness of the support piece on the side where the driven gears 18 and 19 are disposed becomes thinner by the thickness of the driven gears 18 and 19. In addition,
In this embodiment, the drive gear 8 is connected to the fifth counterweight 6e.
It is attached to the front. Therefore, it was possible to make the rear support piece 11 thinner and the front support piece 10 thicker. Therefore, even though a larger torsional vibration is applied to the front support piece 10 than to the rear support piece 11, the adverse effects of the torsional amplitude are suppressed to a low level.

Furthermore, in this embodiment, since the drive gear 8 and both driven gears 18 and 19 are helical gears, the meshing ratio is greater than that of spur gears, and gear hammering noise can be reduced. On the other hand,
When the first driven gear 18 rotates, the arrow C in FIG.
As shown, a thrust force directed forward of the crankshaft 1 acts on the first driven gear 18, and the first weight 13 hits the support piece 10 on the front side of the balancer case 9. However, since the rigidity of the front support piece 10 is increased as described above, the first weight 13 is received by the front support piece 10, and the support piece 10 does not deform.

It should be noted that the present invention is not limited to the configuration of the embodiment described above, and may be modified as desired without departing from the spirit of the invention, for example, as described below. (1) In the above embodiment, the thickness of the first and second weights 13 and 14 was set so that they fit within the longitudinal length L2 of the third crank journal 3c, but even if the same thickness is expanded, good. However, in this case, the support piece 1 of the balancer case 9
It is necessary to shift 0 and 11 back and forth, and doing so is slightly disadvantageous compared to the previous embodiment in terms of an increase in gear hitting noise, thrust hitting noise, etc. due to bending vibration and torsional vibration. (2) The drive gear 8 may be attached to the rear of the fourth counterweight 6d instead of the fifth counterweight 6e. In this case, the support piece 10 on the front side of the balancer case 9
The driven gears 18 and 19 are fixed to the front of each weight 13 and 14. Then, the thickness of the support piece 11 on the rear side of the balancer case 9 is increased, and the helical directions of the drive gear 8 and the first driven gear 18 are set in a direction that generates a rearward thrust force. In other words,
It is preferable to change the embodiment in the opposite direction.

[0024]

As described in detail above, according to the present invention, a driving gear that rotates integrally with the crankshaft and a driven gear that meshes with the driving gear and rotates integrally with a vibration damping weight are provided. Since the helical gear is used, the axial length of the weight can be made longer than in the case of a spur gear, and the weight has the excellent effect of being able to have a shape with high weight efficiency.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of a crankshaft and a balancer device.

FIG. 2 is a sectional view taken along the line AA in FIG. 1;

FIG. 3 is an exploded perspective view of the balancer device.

FIG. 4 is a diagram schematically showing the bending vibration mode of the crankshaft at 450 Hz.

FIG. 5 is a diagram schematically showing the bending vibration mode of the crankshaft at 200 Hz.

FIG. 6 is a diagram schematically showing the torsional vibration mode of the crankshaft at 450 Hz.

FIG. 7 is a partially cutaway front view of a conventional crankshaft and balancer device.

8 is a sectional view taken along line BB in FIG. 7. FIG.

[Explanation of symbols]

1 crankshaft, 8 driving gear, 13 first weight, 18 first driven gear

Claims (1)

[Claims] Claim 1: A driving gear is rotatably attached to an intermediate portion of a crankshaft, and a vibration damping weight is rotatably provided separately from the crankshaft, and the weight is provided with a driven gear that meshes with the driving gear. An engine balancer device for damping engine vibrations by rotating the weight when the crankshaft rotates, wherein the driving gear and the driven gear are helical gears. Device.