JPH11280842A - Drive force transmitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive force transmitting device which can reduce the diameter of a drive force transmitting member such as a gear as small as possible so as to make the device to be small-sized. SOLUTION: A drive force transmitting device includes a first gear and a second gear 24 which are arranged in parallel on one and the same axis, and a damping mechanism which couple the gears in their rotating directions. The damping mechanism incorporates four coil springs 32a, 32b, 33a, 33b which are laid in recesses 29a, 29b formed in the second gear 24 so as to be circumferentially extended, and which expand linearly, radial of the second gear 24. Further, the coil springs 32a, 32b, 33a, 33b have longitudinal both end parts having a diameter which is smaller than that of the intermediate parts thereof. Accordingly, the minimum diameters of the gears are set to be small so that the both ends thereof are prevented from being made into contact with the inner peripheral surfaces of the recesses 29, 29a when the coil springs 32a, 32b, 33a, 33b are compressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force transmission device suitable for application to a balancer device of an internal combustion engine.

[0002]

2. Description of the Related Art Generally, in an internal combustion engine such as an on-vehicle engine, a piston is reciprocated by combustion of fuel, and the reciprocating movement of the piston is converted into rotation of a crankshaft, which is an output shaft, by a connecting rod. I'm trying to get When the piston reciprocates, an inertial force of the piston is generated in the same moving direction. However, in order to operate the internal combustion engine smoothly, it is preferable that the inertial force be as close to "0" as possible.

Conventionally, therefore, a balancer device is provided in an internal combustion engine so that the inertial force of the piston approaches "0". This balancer device includes a balance shaft extending parallel to a crankshaft of the internal combustion engine. The balance shaft is supported rotatably about its own axis, and a weight is mounted on the outer peripheral surface of the shaft so as to be eccentric with respect to the axis. When the balance shaft is rotated, the weight rotates with the shaft and reciprocates in the movement direction of the piston.

Accordingly, by rotating the balance shaft in synchronization with the crankshaft, the inertial force of the weight acts in the direction of movement of the piston, and the inertial force of the weight cancels the inertial force of the piston to reduce the inertial force to "0". ". In order to make the inertia force “0” in this way, it is necessary to rotate the crankshaft and the balance shaft in synchronization,
The synchronized rotation is realized by transmitting the rotation of the crankshaft to the balance shaft via the driving force transmission device.

FIG. 7 shows an example of the driving force transmitting device described in Japanese Utility Model Laid-Open Publication No. Sho 61-106647. The driving force transmission device described in the publication is
Disc-shaped holder 92 fixed to balance shaft 91
And an annular gear 93 fitted on the outer peripheral surface of the holder 92 and meshing with a gear (not shown) of the crankshaft. A notch 94 is formed between the outer peripheral surface of the holder 92 and the inner peripheral surface of the gear 93 by recessing both of them. Further, the notch 94
Inside, the holder 92 and the gear 93 are connected to the balance shaft 9.
A coil spring 95 is provided for connecting to each other in a rotational direction about one axis.

[0006] In the driving force transmission device configured as described above, the rotation of the crankshaft is transmitted to the gear 93, and the rotation of the gear 93 is transmitted to the holder 92 and the balance shaft 91 via the coil spring 95. When the crankshaft rotates, torque fluctuations occur in the rotation direction of the crankshaft. When the torque fluctuations are transmitted to the holder 92 from the gear 93, the coil springs 95 expand and contract and absorb the torque fluctuations. Accordingly, torque fluctuations of the crankshaft are not transmitted to the balance shaft 91 of the balancer device, and it is possible to prevent the balancer device from generating vibrations or the like due to the torque fluctuations and generating abnormal noise.

[0007]

By transmitting the rotation of the crankshaft to the balance shaft 91 by using the driving force transmission device described in the above publication, the torque fluctuation of the crankshaft is transmitted to the balancer device side. Can be prevented.

However, when the coil spring 95 is compressed to absorb the torque fluctuation, both ends in the longitudinal direction of the spring 95 are enlarged, and the distance between the end and the inner wall surface of the notch 94 is short. And it is easy for them to come into contact with each other. If such contact occurs frequently, the inner wall surface of the notch 94 wears, leading to a reduction in the strength of the gear 93.

Therefore, in order to prevent the contact, the width of the notch 94 in the radial direction of the holder 92 and the gear 93 is increased, and both ends of the coil spring 95 and the notch 94 are formed.
It is also conceivable to increase the distance to the inner surface of the vehicle. However, when the width of the cutout portion 94 is increased as described above, it is necessary to increase the radial thickness of the holder 92 and the gear 93 in order to maintain the strength of the holder 92 and the gear 93. The enlargement of the holder 92 and the gear 93 based on the thickness increase in the direction cannot be ignored.

In the driving force transmission device described in the above publication, since the holder 92 and the gear 93 are arranged in the radial direction of the balance shaft, the diameter of the gear 93 increases, and the driving force transmission device increases in size. . In particular, when the driving force transmission device is applied to a device assembled to an internal combustion engine, such as a balancer device, an increase in the size of the gear 93 greatly hinders a reduction in the size of the internal combustion engine.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a driving force transmission device which can reduce the size of a driving force transmission member such as a gear as small as possible. It is in.

[0012]

In order to achieve the above object, according to the first aspect of the present invention, there are provided first and second driving force transmitting members which are located on the same axis and are rotatable about a coaxial line. And a buffer mechanism for connecting the first and second driving force transmission members to each other in the direction of rotation thereof, wherein the rotation of the first driving force transmission member is performed via a coil spring provided in the buffer mechanism. In the driving force transmitting device for transmitting to the second driving force transmitting member, the first and second driving transmitting members are provided in parallel in the axial direction, and the coil spring is disposed between the first and second driving transmitting members. And the both ends in the longitudinal direction of the spring were formed smaller in diameter than the central part in the longitudinal direction.

When the rotation of the first driving force transmitting member is transmitted to the second driving force transmitting member via the coil spring, the coil spring is compressed, and both ends in the longitudinal direction of the spring and both driving force transmitting members are transmitted. When the distance to the member becomes shorter,
Both are likely to come into contact. However, according to the configuration, both ends in the longitudinal direction of the coil spring are formed smaller in diameter than the central portion in the longitudinal direction, and the first and second driving force transmitting members are arranged in parallel in the axial direction. When the diameter of the force transmitting member is set to a minimum value at which the driving force transmitting member does not contact the longitudinal ends of the coil spring, the driving force transmitting members can be made smaller in diameter.

According to a second aspect of the present invention, in the first aspect of the present invention, the coil spring extends in a direction perpendicular to the axis, and the buffer mechanism holds the coil spring in a compressed state. Are provided in parallel.

According to this structure, since the pair of seat portions sandwiching the coil spring are parallel, the both ends in the longitudinal direction of the spring are in contact with the seat portion, so that the seat portion is excessively bent. Wear is prevented.

According to a third aspect of the present invention, in the first aspect of the present invention, the coil spring extends in a direction perpendicular to the axis and is disposed so as to be curved toward a side approaching the axis in its longitudinal direction. It was to be done.

According to this configuration, when the first and second driving force transmitting members rotate, the coil spring is linearly extended by centrifugal force. Since the coil spring becomes linear when the first and second driving force transmitting members rotate as described above, the minimum diameter of the two driving force transmitting members is set such that the spring does not contact the two driving force transmitting members. It will be possible to make it even smaller.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the first driving force transmitting member is rotatably mounted on a balance shaft of a balancer device provided in the internal combustion engine. The second driving force transmitting member is fixed so as to be integrally rotatable with the balance shaft.

The enlargement of the driving force transmission device applied to the balancer device of the internal combustion engine greatly hinders the miniaturization of the engine, but the first and second driving force transmission members of the driving force transmission device are made as small as possible. According to the above configuration, it is possible to reduce the size of the device and to suitably reduce the size of the internal combustion engine.

According to a fifth aspect of the present invention, in the invention of the fourth aspect, a third driving force transmitting member to which the rotation of the second driving force transmitting member is transmitted is further provided, and the third driving force transmitting member is provided. The transmission member was fixed to another balance shaft provided in parallel with the balance shaft so as to be integrally rotatable.

According to this configuration, in a balancer device provided with two balance shafts, the first and second driving force transmitting members of the driving force transmitting device are made as small as possible, whereby
The distance between the balance shafts can be minimized. Therefore, downsizing of the balancer device,
As a result, the size of the internal combustion engine can be suitably reduced.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the buffer mechanism includes a recess formed between opposing surfaces of the first and second driving force transmitting members. And a spring holding means for holding the coil spring such that the coil spring is compressed when the first and second driving force transmitting members rotate relative to each other, and an edge of the spring holding means. Chamfered.

According to the above construction, since the edge of the spring holding means for holding the coil spring is chamfered, the spring holding means is moved to the first position.
In addition, when the holding means is fitted into the recess formed between the opposing surfaces of the second driving force transmitting member, the edge of the holding means is less likely to be caught by the first and second driving force transmitting members. Therefore, the coil spring holding means can be easily assembled to the first and second driving force transmitting members.

According to a seventh aspect of the present invention, in the first aspect of the present invention, the first driving force transmitting member is formed of a resin. When the first driving force transmitting member is formed of a resin for the purpose of improving quietness, the driving force transmitting member usually needs to be formed large in order to ensure strength. However, according to the same configuration in which the first driving force transmission member and the second driving force transmission member are connected via the coil spring of the buffer mechanism,
Even if the first driving force transmitting member is not enlarged, the strength of the first driving force transmitting member is sufficient. Therefore, while improving quietness, the first
It is possible to suppress an increase in the size of the driving member.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the present invention is applied to a balancer device for an automobile engine will be described below with reference to FIGS.

As shown in FIG. 1, a crankshaft 11, which is an output shaft of the engine, is rotatably supported on an axis of the shaft 11 at a lower end of a cylinder block 12 of the engine. This crankshaft 1
1 has a piston via a connecting rod (both not shown)
Are connected. During the operation of the engine, the reciprocating movement of the piston in the vertical direction in the drawing is converted into rotation of the crankshaft 11 by the connecting rod. The crankshaft 11 is provided with a metal crankshaft gear 13 having bevels 13a.
1 and is fixed so as to be able to rotate integrally therewith.

At the lower end of the cylinder block 12, a balancer device 15 for canceling the inertial force of the piston acting in the moving direction of the piston during operation of the engine is mounted. The balancer device 15 includes a pair of housings 1.
First and second balance shafts (only the first balance shaft is shown in FIG. 1) supported rotatably between the first and second balance shafts 6a and 16b in a state parallel to the crankshaft 11.
8 is provided. Weights 19 are attached to the outer peripheral surfaces of the first and second balance shafts 17 and 18 eccentrically with respect to the axes of the shafts 17 and 18.

The first and second balance shafts 1
The rotation of the crankshaft 11 is transmitted to 7 and 18 via the crankshaft gear 13 and the driving force transmission device 21. When the rotation of the crankshaft 11 is transmitted to the first and second balance shafts 17 and 18 in this manner, the shafts 11, 17 and 18 rotate in synchronization. When the first and second balance shafts 17 and 18 rotate, the shafts 17 and 1 are rotated.
8, the weight 19 rotates and reciprocates in the moving direction of the piston (vertical direction in the figure).

Therefore, the weight 19 is reciprocally displaced by the synchronized rotation of the crankshaft 11 and the first and second balance shafts 17 and 18, and the inertia force of the weight 19 is moved in the moving direction of the piston (vertical direction in the drawing). ), The inertia of the weight cancels the inertia of the piston, and the inertia becomes “0”. That is, the mass of the weight 19 and the shafts 17 and 1 are adjusted so that the inertial force of the weight 19 and the inertial force of the piston cancel each other to become “0”.
The mounting position and the like in the circumferential direction of 8 are adjusted in advance.

Next, the detailed structure of the driving force transmission device 21 will be described. As shown in FIG. 2, the driving force transmission device 21 includes a gear mechanism 22 for transmitting the rotation of the crankshaft 11 to the first balance shaft 17. The detailed structure of the gear mechanism 22 is shown in FIG. As shown in the figure, the gear mechanism 22 includes first and second gears 23 and 24 provided in parallel on the axis of the first balance shaft 17, and the gears 23 and 24 are centered on the axis. And a buffer mechanism 25 that is connected in the rotation direction.

The first gear 23 is formed in a disk shape from resin and has bevels 23a on the outer periphery. In the first gear 23, a through hole 26 having a diameter slightly larger than that of the first balance shaft 17 is provided at the center thereof, and the first balance shaft 17 is inserted into the through hole 26. . When the first balance shaft 17 is inserted into the through hole 26 in this manner, the first gear 23
Can rotate with respect to the first balance shaft 17.

The second gear 24 is formed in a disk shape from metal, and has bevels 24a on the outer periphery. In the second gear 24, a through hole 27 having the same diameter as the first balance shaft 17 is provided at the center thereof, and the first balance shaft 17 is press-fitted into the through hole 27.
When the first balance shaft 17 is press-fitted into the through hole 27 in this manner, the second gear 24 is fixed to the first balance shaft 17 so as to be integrally rotatable.

The surface of the second gear 24 facing the first gear 23 is dented, and the inner peripheral surface of the depression is the second surface.
A pair of projections 28 are provided to project toward the center of the gear 24. The protrusions 28 define the inside of the recess of the second gear 24 as a pair of concave portions 29a and 29b extending in an arc shape. The circumferential side surfaces 28a and 28b of the protrusion 28 are
The closer to the center of the second gear 24, the more the two side surfaces 28
a and 29b are formed in an oblique shape so that the distance between them becomes small.

The buffer mechanism 25 includes the holding plates 30a, 3
0b, 31a, 31b and coil springs 32a, 3
2b, 33a, 33b and a holder 34 are provided.
The holding plates 30a, 30b, 31a, 31b are formed by bending both ends of a substantially arc-shaped plate in the longitudinal direction to the same side by 90 °. Both ends in the longitudinal direction of these sandwiching plates 30a, 30b, 31a, 31b are respectively provided with sheet portions 35a, 35b, 36a, 36b.
It has become.

One end of each of the holding plates 30a and 31a is overlapped in the thickness direction of the plates 30a and 31a in a state where the sheet portions 35a and 36a face each other. In this state, the holding plates 30a, 3
A coil spring 32a is disposed between one of the seat portions 35a and 36a in 1a, and a coil spring 33a is disposed between the other seat portions 35a and 36a. In these coil springs 32a and 32b, both ends in the longitudinal direction are formed to be smaller in diameter than the central part in the longitudinal direction.

One end of each of the sandwiching plates 30b and 31b is also in a state where the sheet portions 35b and 36b face each other, and in a state where the one sheet portion 35b and 36b of the plates 30b and 31b face each other. 3
0b and 31b in the thickness direction. In this state, the coil spring 32b is disposed between the one sheet portions 35b and 36b of the holding plates 30b and 31b, and the coil spring 33b is disposed between the other sheet portions 35b and 36b. Also in these coil springs 32b and 33b, both ends in the longitudinal direction are formed to be smaller in diameter than the central part in the longitudinal direction.

The holding plates 30a, 31a and the coil springs 32a, 33a combined as described above
And the holding plates 30b, 31b and the coil springs 32b, 33b are connected to the two recesses 29 of the second gear 24.
a and 29b.

Here, the holding plates 30a, 30b, 3
FIG. 4 shows an enlarged perspective view of 1a and 31b. One of the sheet portions 35a, 35 provided on the holding plates 30a, 30b
5b (upper side in the figure), the outer surfaces of both edges in the protruding direction are chamfered to be slopes 37a, 37b.
Are formed. Further, the holding plates 31a, 31b
, One of the sheet portions 36a and 36b (the lower one in the drawing) has beveled surfaces 38a and 38b on the outer surfaces of both edges in the protruding direction. The inclination angles of these slopes 37a, 37b, 38a, 38b are relatively acute, for example, 30 ° with respect to the outer surfaces of the seat portions 35a, 35b, 36a, 36b.

As described above, the holding plates 30a, 30b,
Sheet portions 35a, 35b, 36 in 31a, 31b
a and 36b are chamfered to form slopes 37a and 37b.
By forming the b, 38a, 38b, the holding plate 3 can be inserted into the recesses 29a, 29b of the second gear 24 as described above.
The fitting of 0a, 30b, 31a, 31b, etc. becomes easy. That is, when the fitting is performed, the sheet portions 35a, 35b, 36a, 36
The edge of “b” is less likely to be caught on the second gear 24.

The holding plates 30a, 31a, 30b, 3
1b, and coil springs 32a, 33a, 32b,
33b is assembled to the second gear 24, as shown in FIG. 5, the springs 32a, 33a,
32b, 33b are seat portions 35a, 35b, 36a, 3
6b is held in a compressed state.

At this time, one of the sheet portions 35a and 36a of the holding plates 30a and 31a are parallel to each other, and the other sheet portions 35a and 36a are parallel to each other. Also, the holding plates 30b, 31b
, One of the sheet portions 35b, 36b is parallel to each other, and the other sheet portion 35b, 36b is parallel to each other. That is, the seat portions 35a, 35b,
The inclination angles of the side surfaces 28a, 28b of the protrusion 28 of the second gear 24 with which the 36a, 36b are in contact are adjusted in advance to a value suitable for the parallel arrangement of the seat portions 35a, 35b, 36a, 36b.

Accordingly, the coil springs 32a, 32
b, 33a, 33b are compressed in a state of extending linearly in the radial direction of the second gear 24, and both ends of the springs 32a, 32b, 33a, 33b are seated at the seat portions 35a, 35b, 36a, 36b is not hit. Therefore, the coil springs 32a, 32
b, 33a, 33b and sheet portions 35a, 35
b, 36a, 36b, and the sheet portion 35 by one-sided contact
a, 35b, 36a, 36b is prevented from being excessively worn.

On the other hand, as shown in FIG.
The holder 34 is attached to the surface facing the second gear 24 by a pair of pins 39 so as to be integrally rotatable with the first gear 23. The holder 34 is formed in a ring shape, and a pair of protrusions 40 projecting toward the center of the holder 34 are provided on the inner peripheral surface of the holder 34. The pair of protrusions 40 are located corresponding to the pair of protrusions 28 provided on the second gear 24 and are formed in the same shape as the protrusions 28. That is, the circumferential side surfaces 40a and 40b of the protrusion 40 are formed in an oblique shape such that the closer to the center of the holder 34, the smaller the distance between the both side surfaces 40a and 40b.

By attaching such a holder 34 to the first gear 23, the second gear 2
A pair of concave portions 41a and 41b extending in an arc shape defined by the pair of protrusions 40 are formed on the surface facing the pair. Then, the holder 3 attached to the first gear 23
4 and the protrusion 28 of the second gear 24 shown in FIG.
Are overlapped with each other in a state where the sheet portions 35a and 35b are in contact with the protrusion 28, and the sheet portion 3
The protrusion 40 of the holder 34 is fitted between 6a and 36b. This fitting is performed by the seat portions 35a, 35b, 36
a, 36b are chamfered to form slopes 37a, 37b.
Since b, 38a and 38b (FIG. 4) are formed, there is no catch between the edge and the holder 34,
It will be done easily.

In the state where such fitting is performed, the seat portions 35a, 35b, 36a, and 36b are not only the protrusions 28 of the second gear 24 but also the protrusions 4 of the holder 34.
It comes in contact with zero. Therefore, when the first and second gears 23 and 24 rotate relative to each other, the two protruding portions 28 and 40 are displaced in the circumferential direction to push the holding plates 30a and 31a to the side for contracting in the circumferential direction.
1b is pushed to the side of contraction in the circumferential direction. As a result, the distance between each pair of seat portions 35a, 35b, 36a, 36b sandwiching each of the coil springs 32a, 32b, 33a, 33b becomes shorter, and the springs 32a, 32b,
33a and 33b are compressed.

In the gear mechanism 22 configured as described above, the first gear 23 is connected to the crankshaft 11 (FIG. 1).
The second gear 24 is engaged with the crankshaft gear 13 attached to the third gear 4 as shown in FIG.
2 is engaged. The third gear 42 has helical teeth 42a on its outer peripheral portion, and the first balance shaft 17
Are fixed to a second balance shaft 18 provided in parallel with the first shaft so as to be integrally rotatable. In the present embodiment, the driving force transmission device 21 is constituted by the third gear 42 and the gear mechanism 22.

The rotation of the crankshaft 11 is
The power is transmitted to the first balance shaft 17 via the crankshaft gear 13 and the gear mechanism 22,
The power is transmitted to the second balance shaft 18 via the second and third gears 42. Thus, the crankshaft 11 and the first and second balance shafts 17 and 18 rotate synchronously, and the inertial force of the piston is canceled by the inertial force of the weight 19.

Next, the operation of the driving force transmission device 21 configured as described above will be described. When the crankshaft 11 (FIG. 1) is rotated by the reciprocating movement of the piston, the rotation of the shaft 11 is transmitted via the crankshaft gear 13 to the first gear 23 of the gear mechanism 22 in the driving force transmission device 21.
Is transmitted to Since the first gear 23 is formed of resin, the quietness in transmitting the rotation from the crankshaft gear 13 to the first gear 23 is improved as compared with the case where a metal gear is employed. Become. The rotation transmission from the crankshaft gear 13 to the first gear 23 causes the first gear 23 to rotate about the axis of the first balance shaft 17 with respect to the first balance shaft 17. Furthermore,
When the first gear 23 rotates, the rotation is transmitted to the gear mechanism 22.
The second gear 24 and the third gear 24
To the gear 42 (FIG. 2).

When the rotation of the first gear 23 is transmitted to the second gear 24 via the buffer mechanism 25, the gears 2
The relative rotation of the gears 3 and 24 causes the protrusions 28 and 40 of the second gear 24 and the holder 34 shown in FIG. These projections 28, 40
Of the holding plate 30 shown in FIG.
a and 31a are contracted in the circumferential direction, and the holding plates 30b and 31b are contracted in the circumferential direction.
As a result, each of the coil springs 32a, 32b, 33
a, 33b, each pair of sheet portions 35a, 35b,
The distance between 36a, 36b becomes shorter, and the springs 32a, 32b, 33a, 33b are compressed.

Crankshaft 1 by reciprocation of piston
In one rotation, a torque fluctuation occurs in the rotation torque of the shaft 13. However, even if the torque fluctuation causes the first gear 23 to change in the direction of relative rotation with respect to the second gear 24, the coil springs 32a, 32b, 33a, 33b expand and contract,
The change in the relative rotation direction of the first gear is not transmitted to the second gear 24.

The coil springs 32a, 32b,
The expansion and contraction of 33a and 33b also plays a role of absorbing an impact when transmitting rotation from the crankshaft gear 13 to the first gear 23. That is, the impact applied from the crankshaft gear 13 to the first gear 23 during the rotation transmission is caused by the coil springs 32a, 32b, 33a, 33b.
Will be alleviated by the expansion and contraction. Therefore, the first gear 23 made of resin having a lower strength than a metal gear and having sufficient strength without increasing the size of the gear 23 in the thickness direction in order to improve the strength. Becomes

The coil springs 32a, 32b, 33
a and 33b are compressed when the springs 32a and 3b are compressed.
Both ends in the longitudinal direction of 2b, 33a, 33b are enlarged in diameter, and the distance between the both ends and the inner peripheral surfaces of the recesses 29a, 29b, 41a, 41b in the second gear 24 and the holder 34 (FIG. 3) is reduced. . In the present embodiment, the first and second gears 2
The coil springs 32a, 32b, 33a, and 33b are formed such that both ends in the longitudinal direction are smaller in diameter than the central portion in the longitudinal direction.
Accordingly, the diameters of the first and second gears 23 and 24 are set to the minimum value at which the contact between the both ends of the coil springs 32a, 32b, 33a and 33b and the inner peripheral surfaces of the recesses 29a, 29b, 41a and 41b does not occur. The gears 23, 24
Can be made smaller in diameter.

Also, as described above, the first and second gear 2
By making the diameters of the gears 3 and 24 as small as possible, the second balance shaft 18 that rotates about its own axis by the rotation transmission from the second gear 24 to the third gear 42 and the second gear 24 The distance from the first balance shaft 17 to be mounted is minimized. Therefore, the first and second
By minimizing the diameter of the gears 23 and 24 and minimizing the distance between the first and second balance shafts 17 and 18, the size of the balancer device 15 and the size of the engine can be reduced. Will be able to

According to the embodiment described in detail above, the following effects can be obtained. (1) The diameters of the first and second gears 23 and 24 in the driving force transmission device 21 are minimized so that the driving force transmission device 21
Can be reduced in size.

(2) Holding plates 30a, 31a, 30
b, 31b, the coil springs 32a, 32
b, 33a, 33b, each pair of seat portions 35a,
35b, 36a, 36b are parallel. Therefore, the coil springs 32a, 32b, 33a, 33b
Does not hit the sheet portions 35a, 35b, 36a, 36b. Therefore, the coil spring 3
2a, 32b, 33a, 33b at both ends and seat 35
Excessive wear of the sheet portions 35a, 35b, 36a, 36b due to one-side contact with the a, 35b, 36a, 36b can be prevented.

(3) An increase in the size of the driving force transmission device 21 applied to the engine balancer device 15 greatly hinders downsizing of the engine.
Since the diameters of the first and second gears 23 and 24 can be made as small as possible, the size of the device 21 can be reduced, and the size of the engine can be reduced appropriately.

(4) First and second balance shafts 1
In the balancer device 15 provided with the first and second gears 23, 24 in the driving force transmission device 21.
By reducing the diameter of the balance shaft 1
The distance between 7 and 18 can be minimized. Therefore, the size of the balancer device 15 and the size of the engine can be suitably reduced.

(5) In the present embodiment, the holding plate 30
a, 30b, 31a, 31b
b, 36a, and 36b are chamfered to form slopes 37a,
37b, 38a and 38b were formed. Therefore, the holding plate 30 is inserted into the recesses 29a and 29b of the second gear 24.
When fitting a, 30b, 31a, 31b, etc., the edges of the sheet portions 35a, 35b, 36a, 36b are less likely to be caught by the second gear 24. Further, when the projection 40 of the holder 34 and the projection 28 of the second gear 24 overlap in the thickness direction, the sheet portions 35a, 3
5b and between the sheet portions 36a and 36b.
The projections 40 are fitted, but during this fitting, the edges of the sheet portions 35a, 35b, 36a, 36b are less likely to be caught on the holder 34. Therefore, the holding plates 30a, 30b, 31a, 31b can be easily assembled to the first and second gears 23, 24.

(6) The seat portions 35a, 35
b, 36a, 36b, slopes 37a, 37b, 38a, 3
8b is formed at a relatively acute angle of 30 [deg.] With respect to the outer side surfaces of the sheet portions 35a, 35b, 36a, 36b. Therefore, the work of inserting the holding plates 30a, 30b, 31a, 31b into the first and second gears 23, 24 becomes easier.

(7) Normally, when the first gear 23 is made of resin for the purpose of improving quietness, the first gear 23 must be enlarged in the thickness direction in order to secure strength. However, in the present embodiment, when the rotation is transmitted from the crankshaft gear 13 to the first gear 23, the gear 1
The shock applied to the gear 23 from the gear 3 is reduced by the expansion and contraction of the coil springs 32a, 32b, 33a, 33b. Therefore, even if the first gear 23 made of resin having lower strength than that made of metal is adopted, the gear 23 is not enlarged in the thickness direction to improve the strength.
Can have sufficient strength. Therefore, it is possible to suppress an increase in the size of the first gear 23 while improving quietness.

The present embodiment can be modified, for example, as follows. The first gear 23 may be formed of a material other than resin (for example, metal). The inclination angles of the slopes 37a, 37b, 38a, 38b of the seat portions 35a, 35b, 36a, 36b are set to 3 with respect to the outer surfaces of the seat portions 35a, 35b, 36a, 36b.
Although 0 ° was used, another value (for example, 45 °) may be used.

Each of the sheet portions 35a, 35b, 36a, 3
6b, two slopes 37a, 37b, 38
a, 38b may be omitted. In this case, the labor for forming the slopes 37a, 37b, 38a, 38b can be reduced.

· The slopes 37a, 37b, 38a, 3
8b is omitted, and the slopes 37a, 37b, 38a, 3
The labor for forming 8b may be omitted. In this embodiment, two balance shafts 17 and 18 are used.
Although the balancer device 15 including the above is exemplified, the number of balance shafts may be appropriately changed according to the number of cylinders of the engine.

In the present embodiment, the gears 23, 24, and 42 are exemplified as the driving force transmitting members, but sprockets and pulleys may be employed as the driving force transmitting members instead. In these cases, the rotation is transmitted not through the meshing of the gears but through a chain or a belt.

In the present embodiment, the driving force transmission device 21 is applied to a balancer device of an engine. However, the driving force transmission device 21 may be applied to other devices. In the present embodiment, the coil springs 32a, 32b,
33a and 33b are formed in a straight line. Instead, as shown by a chain line in FIG.
2a, 32b, 33a, 33b in the longitudinal direction
May be curved to the side approaching the center of the gear 24. In this case, the coil springs 32a, 32b, 33a, 3
Sheet portions 35a, 35b, 36 that sandwich the pair 3b.
a and 36b are not parallel to each other, but are expanded toward the center of the second gear 24. With such a configuration, when the gear mechanism 22 of the driving force transmission device 21 rotates, the coil springs 32a, 32
b, 33a, 33b become linear. For this reason, the minimum diameter of the first and second gears 23 and 24 in which both ends of the coil springs 32a, 32b, 33a and 33b do not contact the inner peripheral surfaces of the recesses 29a, 29b, 41a and 41b are further reduced. In addition, the size of the driving force transmission device 21 can be further reduced.

In the present embodiment, four coil springs 32a, 32b, 33a, 33b are provided in the shock absorbing mechanism 25, but the number may be changed to, for example, two. In this case, the coil springs 32a, 32b, 33
a, 33b according to the number of holding plates 30a, 30b.
The numbers of b, 31a, 31b, etc. will also be changed.

[0067]

According to the first aspect of the present invention, both ends in the longitudinal direction of the coil spring are formed smaller in diameter than the central part in the longitudinal direction, and the first and second driving force transmitting members are arranged in parallel in the axial direction. Therefore, when the diameter of the driving force transmitting members is set to a minimum value at which the driving force transmitting members do not come into contact with both ends in the longitudinal direction of the coil spring, the driving force transmitting members are reduced in diameter. Can be. Therefore, the diameter of the first and second driving force transmitting members is made as small as possible,
The size of the driving force transmission device can be reduced.

According to the second aspect of the present invention, since the pair of seat portions sandwiching the coil spring is parallel, the longitudinal end portions of the spring are in one-side contact with the seat portion. Excessive wear of the part can be prevented.

According to the third aspect of the present invention, when the first and second driving force transmitting members rotate, the coil spring is linearly extended by centrifugal force. Since the coil spring becomes linear when the first and second driving force transmitting members rotate as described above, the minimum diameter of the two driving force transmitting members is set such that the spring does not contact the two driving force transmitting members. It will be possible to make it even smaller.

According to the fourth aspect of the present invention, the enlargement of the driving force transmission device applied to the balancer device of the internal combustion engine greatly hinders the downsizing of the engine. Since the diameter of the second driving force transmitting member can be made as small as possible, it is possible to reduce the size of the device and to suitably reduce the size of the internal combustion engine.

According to the fifth aspect of the present invention, in the balancer device provided with two balance shafts, the first and second driving force transmitting members of the driving force transmitting device are made as small as possible so that the balance shafts are formed. Can be minimized. Therefore, it is possible to suitably reduce the size of the balancer device and, consequently, the size of the internal combustion engine.

According to the sixth aspect of the present invention, since the edge of the spring holding means for holding the coil spring is chamfered, the spring holding means is connected to the first and second driving means. When fitted into the recess formed between the opposing surfaces of the force transmitting member, the edge of the holding means is in the first position.
And it becomes difficult to be caught by the second driving force transmitting member. Therefore, the coil spring holding means can be easily assembled to the first and second driving force transmitting members.

According to the seventh aspect of the present invention, when the first driving force transmitting member is formed of a resin for the purpose of improving quietness, the driving force transmitting member is usually large in size to ensure strength. The first driving force transmitting member and the second driving force transmitting member are connected via a coil spring of a shock absorbing mechanism, thereby increasing the size of the first driving force transmitting member. Without this, the strength of the member becomes sufficient. Therefore, it is possible to suppress an increase in the size of the first driving member while improving quietness.

[Brief description of the drawings]

FIG. 1 is a side view showing a balancer device and an engine to which a driving force transmission device according to an embodiment is applied.

FIG. 2 is a front view of the engine showing a manner of connecting a crankshaft and a balancer device by the driving force transmission device.

FIG. 3 is an exploded perspective view showing an internal structure of a gear mechanism provided in the driving force transmission device.

FIG. 4 is an enlarged perspective view showing a holding plate of the gear mechanism.

FIG. 5 is a front view showing an assembling state of a holding plate and a coil spring with respect to a second gear;

FIG. 6 is a front view showing another example of a mode of assembling the holding plate and the coil spring to the second gear.

FIG. 7 is a front view showing a conventional example of a driving force transmission device.

[Description of Signs] 15: Balancer device, 17: First balance shaft,
18 second balance shaft, 21 driving force transmission device, 22 gear mechanism, 23 first gear, 24 second gear, 25 buffer mechanism, 30a, 30b, 31a, 31
b ... Nipping plate, 32a, 32b, 33a, 33b ...
Coil spring, 34 ... holder, 35a, 35b, 3
6a, 36b: sheet part, 37a, 37b, 38a, 3
8b: slope, 42: third gear.

Claims (7)

[Claims] 1. A first and second driving force transmitting member which is rotatable about a coaxial line and located on the same axis, and the first and second driving force transmitting members are connected to each other in a direction of rotation thereof. A driving mechanism for transmitting the rotation of the first driving force transmitting member to a second driving force transmitting member via a coil spring provided in the buffering mechanism. A second drive transmission member is provided in parallel in the axial direction, the coil spring is disposed between the first and second drive transmission members, and both ends of the spring in the longitudinal direction are located closer to the center in the longitudinal direction. A driving force transmission device characterized in that the driving force transmission device also has a small diameter. 2. The driving force transmission device according to claim 1, wherein the coil spring extends in a direction orthogonal to the axis, and the buffer mechanism includes a pair of clamps that clamp the coil spring in a compressed state. A driving force transmission device, wherein the seat portions are provided in parallel. 3. The driving force transmission device according to claim 1, wherein the coil spring extends in a direction perpendicular to the axis and is curved in a longitudinal direction of the coil spring toward a side approaching the axis. 4. The first driving force transmitting member is rotatably mounted on a balance shaft of a balancer device provided in an internal combustion engine, and the second driving force transmitting member is fixed to be integrally rotatable with the balance shaft. The driving force transmission device according to claim 1, wherein 5. The driving force transmitting device according to claim 4, further comprising a third driving force transmitting member to which rotation of the second driving force transmitting member is transmitted, wherein the third driving force transmitting member is connected to the third driving force transmitting member. A driving force transmission device fixed to another balance shaft provided in parallel with the balance shaft so as to be integrally rotatable. 6. The driving force transmission device according to claim 1, wherein the buffer mechanism is fitted into a concave portion formed between opposing surfaces of the first and second driving force transmission members. And a spring holding means for holding the coil spring such that the coil spring is compressed when the first and second driving force transmitting members rotate relative to each other, and chamfering an edge of the spring holding means. A driving force transmission device characterized by applying the following. 7. The driving force transmission device according to claim 1, wherein the first driving force transmission member is formed of a resin.