JP3539196B2 - Driving force transmission device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a driving force transmission device suitable for being applied to a balancer device of an internal combustion engine.
[0002]
[Prior art]
Generally, in an internal combustion engine such as an on-vehicle engine, a piston is reciprocated by burning fuel, and the reciprocating movement of the piston is converted into rotation of a crankshaft, which is an output shaft, by a connecting rod to obtain a driving force. I have. 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.
[0003]
Therefore, conventionally, a balancer device is provided in the internal combustion engine so that the inertia 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.
[0004]
Therefore, by rotating the balance shaft in synchronization with the crankshaft, the inertial force of the weight works in the direction of movement of the piston, and the inertial force of the weight cancels the inertial force of the piston to set the inertial force to "0". Will be able to do it. In order to reduce the inertial force to “0”, it is necessary to rotate the crankshaft and the balance shaft in synchronization, and the synchronized rotation balances the rotation of the crankshaft through the driving force transmission device. This is achieved by transmitting to the shaft.
[0005]
Here, as an example of the driving force transmission device, FIG. 7 shows a device described in Japanese Utility Model Laid-Open Publication No. 61-106647. The driving force transmitting device described in the publication has a disk-shaped holder 92 fixed to a balance shaft 91, and an annular ring fitted to the outer peripheral surface of the holder 92 and meshing with a gear (not shown) of a crankshaft. A gear 93 is provided. 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, a coil spring 95 for connecting the holder 92 and the gear 93 to each other in a rotational direction about the axis of the balance shaft 91 is provided in the notch 94.
[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, a torque fluctuation occurs in the rotation direction of the crankshaft. When the torque fluctuation is transmitted from the gear 93 to the holder 92, the coil spring 95 expands and contracts and absorbs the torque fluctuation. Accordingly, torque fluctuations of the crankshaft are not transmitted to the balance shaft 91 of the balancer device, and it is possible to prevent vibrations and the like from occurring in the balancer device due to the torque fluctuations and noise.
[0007]
[Problems to be solved by the invention]
By transmitting the rotation of the crankshaft to the balance shaft 91 using the driving force transmission device described in the above publication, it is possible to prevent the torque fluctuation of the crankshaft from being transmitted to the balancer device side. Become.
[0008]
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 in diameter, and the distance between the end and the inner wall surface of the notch 94 is shortened. Both come into contact easily. 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.
[0009]
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 may be increased, and the distance between both ends of the coil spring 95 and the inner surface of the notch 94 may be increased. . 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. Enlargement of the holder 92 and the gear 93 based on the thickness increase in the direction cannot be ignored.
[0010]
Further, 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 is increased and the driving force transmission device is enlarged. In particular, when the driving force transmission device is applied to a device mounted on 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.
[0011]
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 that can reduce the size of a driving force transmission member such as a gear as small as possible. .
[0012]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the first and second driving force transmitting members are located on the same axis and are rotatable about a coaxial line, and the first and second driving forces are provided. A buffer mechanism for connecting the force transmitting members to each other in the rotational direction thereof, and transmitting the rotation of the first driving force transmitting member to the second driving force transmitting member via a coil spring provided in the buffer mechanism. In the driving force transmission device, the first and second drivingPowerA transmission member is provided in parallel in the axial direction, and the coil spring is driven by the first and second drive units.PowerThe coil spring is disposed between the transmission members, and extends in a direction orthogonal to the axis, and extends in its own longitudinal direction.Middle partApproach the axisdirectionCurved toLetArranged, The both ends in the longitudinal direction of the spring are formed to be smaller in diameter than the central part in the longitudinal direction..
[0013]
According to the 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 so that the spring does not contact the two driving force transmitting members. It becomes possible to further reduce the size.
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 the longitudinal end portions of the spring and the two driving force transmitting members are connected. As the distance becomes shorter, both of them become easier to 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 come into contact with the longitudinal ends of the coil spring, the driving force transmitting members can be made smaller in diameter.
[0020]
Claim2In the described invention, the claims1 noteIn the above invention, the first driving force transmission member is rotatably attached to a balance shaft of a balancer device provided in the internal combustion engine, and the second driving force transmission member is fixed to be integrally rotatable with the balance shaft. did.
[0021]
An increase in the size of the driving force transmission device applied to the balancer device of the internal combustion engine greatly hinders downsizing of the engine. However, the first and second driving force transmission members of the driving force transmission device should be as small as possible. According to this configuration, the size of the device can be reduced, and the size of the internal combustion engine can be reduced appropriately.
[0022]
Claim3In the described invention, the claims2In the invention described in the above, a third driving force transmission member to which rotation of the second driving force transmission member is transmitted is further provided, and the third driving force transmission member is provided in parallel with the balance shaft. It is fixed to the shaft so that it can rotate integrally.
[0023]
According to this configuration, in a balancer device provided with two balance shafts, the first and second driving force transmission members of the driving force transmission device are made as small as possible to minimize the distance between the balance shafts. Will be able to do it. Therefore, downsizing of the balancer device and, eventually, downsizing of the internal combustion engine can be suitably achieved.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment in which the present invention is applied to a balancer device for an automobile engine will be described below with reference to FIGS.
[0026]
As shown in FIG. 1, a crankshaft 11, which is an output shaft of the engine, is supported at the lower end of a cylinder block 12 of the engine so as to be rotatable about the axis of the shaft 11. A piston (both not shown) is connected to the crankshaft 11 via a connecting rod. 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. Further, a metal crankshaft gear 13 having bevels 13a is fixed to the crankshaft 11 so as to be integrally rotatable therewith.
[0027]
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 attached. The balancer device 15 includes first and second balance shafts (only the first balance shaft is shown in FIG. 1) 17 rotatably supported between a pair of housings 16a and 16b in a state parallel to the crankshaft 11. , 18 are 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.
[0028]
The rotation of the crankshaft 11 is transmitted to the first and second balance shafts 17 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, 18, the shafts 11, 17, 18 rotate in synchronization. When the first and second balance shafts 17 and 18 rotate, the weight 19 rotates with the shafts 17 and 18 and reciprocates in the movement direction (vertical direction in the drawing) of the piston.
[0029]
Therefore, the weight 19 is reciprocated by the synchronized rotation of the crankshaft 11 and the first and second balance shafts 17, 18, and the inertia force of the weight 19 acts in the moving direction of the piston (vertical direction in the figure). The inertia force of the weight cancels the inertia force of the piston, and the inertia force becomes "0". That is, the mass of the weight 19 and the mounting position of the shafts 17 and 18 in the circumferential direction are adjusted in advance so that the inertial force of the weight 19 and the inertial force of the piston cancel each other to become “0”.
[0030]
Next, a 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 centered on the axis. And a buffer mechanism 25 that is connected in the rotation direction.
[0031]
The first gear 23 is formed in a disk shape by a resin, and has beveled teeth 23a on an outer peripheral portion. 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. . Thus, when the first balance shaft 17 is inserted into the through hole 26, the first gear 23 can rotate with respect to the first balance shaft 17.
[0032]
The second gear 24 is formed of metal in a disk shape 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 pressed 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.
[0033]
The surface of the second gear 24 facing the first gear 23 is dented, and a pair of protrusions 28 projecting toward the center of the second gear 24 are formed on the inner peripheral surface of the depression. Is provided. 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 formed in an oblique shape such that the closer to the center of the second gear 24, the smaller the distance between the side surfaces 28a and 29b.
[0034]
The buffer mechanism 25 includes holding plates 30a, 30b, 31a, 31b, coil springs 32a, 32b, 33a, 33b, and a holder. 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 of the holding plates 30a, 30b, 31a, 31b in the longitudinal direction are sheet portions 35a, 35b, 36a, 36b, respectively.
[0035]
One end of each of the sandwiching 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 coil spring 32a is disposed between one of the sheet portions 35a and 36a of the holding plates 30a and 31a, and the coil spring 33a is disposed between the other sheet 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.
[0036]
Also, one ends of the sandwiching plates 30b and 31b are in a state where the sheet portions 35b and 36b are opposed to each other, and in a state where the one sheet portions 35b and 36b of the plates 30b and 31b are opposed to each other, the same plate 30b and 31b In the thickness direction. In this state, the coil spring 32b is disposed between one of the 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.
[0037]
The holding plates 30a, 31a and the coil springs 32a, 33a and the holding plates 30b, 31b and the coil springs 32b, 33b combined as described above are fitted into the two concave portions 29a, 29b of the second gear 24, respectively. .
[0038]
Here, an enlarged perspective view of the holding plates 30a, 30b, 31a, 31b is shown in FIG. In one of the sheet portions 35a and 35b (upper ones in the drawing) provided on the holding plates 30a and 30b, the outer surfaces of both edges in the protruding direction are chamfered to form inclined surfaces 37a and 37b. I have. Further, in one of the sheet portions 36a and 36b (the lower one in the drawing) provided on the sandwiching plates 31a and 31b, the outer surfaces of both edges in the protruding direction are chamfered to be inclined 38a and 38b. Is formed. 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.
[0039]
As described above, the edges of the sheet portions 35a, 35b, 36a, and 36b in the holding plates 30a, 30b, 31a, and 31b are chamfered to form the inclined surfaces 37a, 37b, 38a, and 38b. The fitting of the holding plates 30a, 30b, 31a, 31b and the like to the concave portions 29a, 29b of the gear 24 becomes easy. That is, when the fitting is performed, the edges of the sheet portions 35a, 35b, 36a, and 36b are less likely to be caught by the second gear 24 by performing the chamfering process.
[0040]
When the holding plates 30a, 31a, 30b, 31b and the coil springs 32a, 33a, 32b, 33b are assembled to the second gear 24, the springs 32a, 33a, 32b as shown in FIG. , 33b are compressed and held by the sheet portions 35a, 35b, 36a, 36b.
[0041]
At this time, one of the sheet portions 35a and 36a of the sandwiching plates 30a and 31a are parallel to each other, and the other sheet portions 35a and 36a are parallel to each other. Further, one of the sheet portions 35b and 36b of the sandwiching plates 30b and 31b are parallel to each other, and the other sheet portions 35b and 36b are parallel to each other. That is, the inclination angles of the side surfaces 28a, 28b of the projection 28 of the second gear 24 with which the seat portions 35a, 35b, 36a, 36b come into contact are values suitable for the parallel arrangement of the seat portions 35a, 35b, 36a, 36b. Is adjusted in advance.
[0042]
Therefore, the coil springs 32a, 32b, 33a, and 33b are compressed while being linearly extended in the radial direction of the second gear 24, and both ends of the springs 32a, 32b, 33a, and 33b are seated. There is no one-side hit at 35a, 35b, 36a, 36b. Therefore, excessive abrasion of the seat portions 35a, 35b, 36a, 36b due to one end of the coil springs 32a, 32b, 33a, 33b and one end of the seat portions 35a, 35b, 36a, 36b is prevented. .
[0043]
On the other hand, as shown in FIG. 3, a holder 34 is attached to a surface of the first gear 23 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 are provided on the inner peripheral surface of the holder 34 so as to protrude toward the center 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 distance between the side surfaces 40a and 40b decreases as the distance from the center of the holder 34 decreases.
[0044]
By attaching such a holder 34 to the first gear 23, a pair of concave portions 41 a extending in an arc shape defined by the pair of protrusions 40 is formed on a surface of the first gear 23 facing the second gear 24. 41b is formed. When the projection 40 of the holder 34 attached to the first gear 23 and the projection 28 of the second gear 24 shown in FIG. The projections 40 of the holder 34 are fitted between the seat portions 35a and 35b and between the seat portions 36a and 36b. Since the edges of the sheet portions 35a, 35b, 36a, and 36b are chamfered to form the inclined surfaces 37a, 37b, 38a, and 38b (FIG. 4), the fitting is performed between the edges and the holder 34. Is easy to be performed without getting caught on the surface.
[0045]
In the state where such fitting is performed, the seat portions 35a, 35b, 36a, and 36b come into contact not only with the protrusion 28 of the second gear 24 but also with the protrusion 40 of the holder 34. . Accordingly, 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 and push the holding plates 30a and 31a in the circumferential direction so as to shrink the holding plates 30b and 31b. Push to shrink 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 is reduced, and the springs 32a, 32b, 33a, 33b are compressed. Become.
[0046]
In the gear mechanism 22 configured as described above, the first gear 23 is meshed with the crankshaft gear 13 attached to the crankshaft 11 (FIG. 1), and the second gear 24 is engaged with the crankshaft gear 13 as shown in FIG. 3 is meshed with the third gear 42. The third gear 42 has beveled teeth 42 a on its outer peripheral portion, and is fixed to the second balance shaft 18 provided in parallel with the first balance shaft 17 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.
[0047]
The rotation of the crankshaft 11 is transmitted to the first balance shaft 17 via the crankshaft gear 13 and the gear mechanism 22, and further transmitted to the second balance shaft 18 via the gear mechanism 22 and the third gear 42. Be transmitted. 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.
[0048]
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 to the first gear 23 of the gear mechanism 22 in the driving force transmission device 21 via the crankshaft gear 13. 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. Further, when the first gear 23 rotates, the rotation is transmitted to the second gear 24 and the third gear 42 (FIG. 2) via the buffer mechanism 25 in the gear mechanism 22.
[0049]
When the rotation of the first gear 23 is transmitted to the second gear 24 via the buffer mechanism 25, the gears 23 and 24 rotate relative to each other, and the second gear 24 and the holder 34 shown in FIG. The protrusions 28 and 40 stacked in the thickness direction are shifted in the circumferential direction. Due to the circumferential displacement of the projections 28, 40, the holding plates 30a, 31a shown in FIG. 5 are contracted in the circumferential direction, and the holding plates 30b, 31b are contracted 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 is reduced, and the springs 32a, 32b, 33a, 33b are compressed.
[0050]
In the rotation of the crankshaft 11 due to the reciprocation of the piston, a torque fluctuation occurs in the rotation torque of the shaft 13. However, even if the first gear 23 fluctuates in the direction of relative rotation with respect to the second gear 24 due to the torque fluctuation, the first spring 23 expands and contracts by the coil springs 32a, 32b, 33a, 33b. The fluctuation in the relative rotation direction of the first gear is not transmitted to the second gear 24.
[0051]
Further, the expansion and contraction of the coil springs 32a, 32b, 33a, 33b also plays a role of absorbing an impact when the rotation is transmitted from the crankshaft gear 13 to the first gear 23. That is, the shock applied from the crankshaft gear 13 to the first gear 23 during the rotation transmission is reduced by the expansion and contraction of the coil springs 32a, 32b, 33a, 33b. Therefore, the first gear 23 made of resin having a lower strength than that made of metal and having sufficient strength without increasing the size of the gear 23 in the thickness direction in order to improve the strength. It becomes.
[0052]
When the coil springs 32a, 32b, 33a, 33b are compressed, both ends in the longitudinal direction of the springs 32a, 32b, 33a, 33b expand, and both ends, the second gear 24 and the holder 34 (FIG. 3). Of the recesses 29a, 29b, 41a, 41b with respect to the inner peripheral surface is reduced. In the present embodiment, the first and second gears 23 and 24 are arranged in parallel on the same axis, and both ends in the longitudinal direction of the coil springs 32a, 32b, 33a and 33b are smaller in diameter than the central part in the longitudinal direction. Is formed. Therefore, the diameters of the first and second gears 23 and 24 are set to the minimum values 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. Then, the gears 23 and 24 can be made smaller in diameter.
[0053]
Further, by making the diameters of the first and second gears 23 and 24 as small as possible, the second gear 24 is rotated around its own axis by rotation transmission from the second gear 24 to the third gear 42. The distance between the balance shaft 18 and the first balance shaft 17 to which the second gear 24 is attached is minimized. Therefore, by minimizing the diameter of the first and second 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 engine can be reduced. Can be suitably reduced in size.
[0054]
According to the embodiment described above, the following effects can be obtained.
(1) The diameter of the first and second gears 23 and 24 in the driving force transmission device 21 is minimized, so that the driving force transmission device 21 can be downsized.
[0055]
(2) In the holding plates 30a, 31a, 30b, 31b, each pair of seat portions 35a, 35b, 36a, 36b holding the coil springs 32a, 32b, 33a, 33b is parallel. Therefore, both ends of the coil springs 32a, 32b, 33a, 33b do not hit against the seat portions 35a, 35b, 36a, 36b. Accordingly, excessive abrasion of the seat portions 35a, 35b, 36a, 36b due to one end of the coil springs 32a, 32b, 33a, 33b and one end of the seat portions 35a, 35b, 36a, 36b can be prevented.
[0056]
(3) The enlargement of the driving force transmission device 21 applied to the engine balancer device 15 greatly hinders downsizing of the engine, but the first and second gears 23 and 24 of the driving force transmission device 21 need to be mounted. Since the diameter can be made as small as possible, the size of the device 21 can be reduced, and the engine can be suitably reduced in size.
[0057]
(4) In the balancer device 15 in which the first and second balance shafts 17 and 18 are provided, the first and second gears 23 and 24 in the driving force transmission device 21 are reduced in diameter as much as possible. , 18 can be minimized. Therefore, the size of the balancer device 15 and the size of the engine can be suitably reduced.
[0058]
(5) In the present embodiment, the slopes 37a, 37b, 38a, 38b are formed by chamfering the sheet portions 35a, 35b, 36a, 36b of the sandwiching plates 30a, 30b, 31a, 31b. Therefore, when the holding plates 30a, 30b, 31a, 31b and the like are fitted into the recesses 29a, 29b of the second gear 24, the edges of the sheet portions 35a, 35b, 36a, 36b are hardly caught by the second gear 24. Become. When the projection 40 of the holder 34 and the projection 28 of the second gear 24 are overlapped in the thickness direction, between the sheet portions 35a and 35b in contact with the projection 28 and between the sheet portions 36a and 36b. The projections 40 of the holder 34 are fitted into the holder 34, but the edges of the sheet portions 35a, 35b, 36a, 36b are less likely to be caught on the holder 34 during this fitting. Therefore, the holding plates 30a, 30b, 31a, 31b can be easily assembled to the first and second gears 23, 24.
[0059]
(6) The slopes 37a, 37b, 38a, 38b of the seat portions 35a, 35b, 36a, 36b are formed at a relatively acute angle of 30 ° with respect to the outer surfaces of the seat portions 35a, 35b, 36a, 36b. ing. Therefore, the work of inserting the holding plates 30a, 30b, 31a, 31b into the first and second gears 23, 24 becomes easier.
[0060]
(7) Normally, when the first gear 23 is formed 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, the shock applied from the gear 13 to the gear 23 when the rotation is transmitted from the crankshaft gear 13 to the first gear 23 is reduced by the expansion and contraction of the coil springs 32a, 32b, 33a, 33b. It will be. Therefore, even if the first gear 23 made of resin having lower strength than that made of metal is adopted, the strength of the gear 23 can be sufficiently increased without increasing the size of the gear 23 in the thickness direction in order to improve the strength. It can be. Therefore, it is possible to suppress an increase in the size of the first gear 23 while improving quietness.
[0061]
Note that the present embodiment can be modified, for example, as follows.
-The first gear 23 may be formed of a material (for example, metal) other than resin.
The inclination angles of the slopes 37a, 37b, 38a, 38b of the seat portions 35a, 35b, 36a, 36b are set to 30 ° with respect to the outer surfaces of the seat portions 35a, 35b, 36a, 36b, but other values ( For example, it may be 45 °).
[0062]
-One of the two slopes 37a, 37b, 38a, 38b formed on each of the sheet portions 35a, 35b, 36a, 36b may be omitted. In this case, the labor for forming the slopes 37a, 37b, 38a, 38b can be reduced.
[0063]
Further, all the slopes 37a, 37b, 38a, 38b may be omitted, and the labor for forming the slopes 37a, 37b, 38a, 38b may be omitted.
In the present embodiment, the balancer device 15 including the two balance shafts 17 and 18 has been illustrated, but the number of balance shafts may be appropriately changed according to the number of cylinders of the engine.
[0064]
In the present embodiment, the gears 23, 24, and 42 are illustrated as the driving force transmitting members, but sprockets, pulleys, and the like 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.
[0065]
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, 33b are made linear, but instead, the coil springs 32a, 32b, 33a, 33b are elongated as shown by a chain line in FIG. The direction may be curved toward the side approaching the center of the second gear 24. In this case, each pair of seat portions 35a, 35b, 36a, 36b sandwiching the coil springs 32a, 32b, 33a, 33b is not parallel to each other, but is expanded toward the center of the second gear 24. . With this configuration, when the gear mechanism 22 of the driving force transmission device 21 rotates, the coil springs 32a, 32b, 33a, and 33b become linear due to centrifugal force. For this reason, the minimum diameter of the first and second gears 23 and 24 where 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.
[0066]
-In this embodiment, although four coil springs 32a, 32b, 33a, and 33b were provided in the buffer mechanism 25, the number may be suitably changed to, for example, two. In this case, the number of the holding plates 30a, 30b, 31a, 31b, etc. is also changed according to the number of the coil springs 32a, 32b, 33a, 33b.
[0067]
【The invention's effect】
According to the first aspect of the 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 so that the spring does not contact the two driving force transmitting members. It becomes possible to further reduce the size.
Further, both ends in the longitudinal direction of the coil spring are formed to have a smaller 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 driving force transmission member is set to the minimum value at which the longitudinal ends of the coil spring do not come into contact with each other, the driving force transmission members can be made smaller in diameter. Therefore, the first and second driving force transmitting members can be made as small as possible in diameter, and the driving force transmitting device can be downsized.
[0071]
Claim2According to the described 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, but the first and second driving force transmission devices of the driving force transmission device Since the diameter of the 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.
[0072]
Claim3According to the described invention, in a balancer device provided with two balance shafts, the first and second driving force transmission members of the driving force transmission device are made as small as possible to minimize the distance between the balance shafts. Can be stopped. Therefore, the size of the balancer device and the size of the internal combustion engine can be suitably reduced.
[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 the crankshaft and the 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 an assembling mode of the holding plate and the coil spring with respect to the second gear;
FIG. 7 is a front view showing a conventional example of a driving force transmission device.
[Explanation of symbols]
Reference numeral 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, 31b: clamping plate, 32a, 32b, 33a, 33b: coil spring, 34: holder, 35a, 35b, 36a, 36b: sheet part, 37a, 37b, 38a, 38b: slope, 42 ... the third gear.

Claims (3)

A first and second driving force transmitting member that is rotatable about a coaxial line that is located on the same axis, and a buffer mechanism that connects the first and second driving force transmitting members to each other in a rotational direction thereof. A driving force transmitting device for transmitting rotation of the first driving force transmitting member to a second driving force transmitting member via a coil spring provided in the buffer mechanism;
The first and second driving force transmitting members are provided in parallel in the axial direction, and the coil spring is disposed between the first and second driving force transmitting members. The spring extends in the orthogonal direction, and its longitudinal middle part is disposed so as to be curved in a direction approaching the axis, and both ends in the longitudinal direction of the spring are formed to have a smaller diameter than the central part in the longitudinal direction. A driving force transmission device characterized by the above-mentioned. The first driving force transmitting member is rotatably attached to a balance shaft of a balancer device provided in the 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 . The driving force transmission device according to claim 2,
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 can be integrally rotated with another balance shaft provided in parallel with the balance shaft. Fixed to
A driving force transmission device characterized by the above-mentioned .

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