JP2000213599A - Damper device and driving force transmitting device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an early deterioration of a damper spring, and decrease the size of an unbalance mass provided on a balance shaft, when applied to a balance device. SOLUTION: A damper device 23 comprises a first and second spring holders 25, 26, and a projecting part 29 having an arc-shaped guide groove 29b is provided on the spring holder 25. The spring holder 26 is composed of a pair of locking pieces 33 provided to project on a plate 32, and a locking piece 35 having a stopper 34 making a regulating part on the center. The locking pieces 33, 35 are formed into an arc shape having the same curvature as the guide groove 29b, and inserted in the guide groove 29b. A damper spring 27 transmitting rotating force of one spring holder 25 to the other spring holder 26 between both spring holders is arranged between the locking pieces 33, 35 and the projecting part 29. The position and the weight of the stopper 34 is set to unbalance a center of gravity of the whole stopper 34 and the damper spring 27 relative to a rotating center of both spring holders 25, 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force transmitting device for an internal combustion engine having a damper device and a balance device.

[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 smoothly operate the internal combustion engine, it is preferable that the inertial force be as close to "0" as possible.

Conventionally, therefore, a balance device is provided in an internal combustion engine so that the inertia force of the piston approaches "0". The balance 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 (unbalance mass) is provided on the outer peripheral surface of the shaft so as to be eccentric with respect to the axis.

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 out the inertial force of the piston to reduce the inertial force. 0 ". In order to make the inertial force “0” in this way, it is necessary to rotate the crankshaft and the balance shaft in synchronization, but the synchronized rotation balances the rotation of the crankshaft through the driving force transmission device. This is achieved by transmitting to the shaft.

Japanese Unexamined Utility Model Publication No. 61-106647 discloses the above-described driving force transmission device shown in FIG. This driving force transmission device includes a disk-shaped holder 92 fixed to a 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 a crankshaft. ing. Recesses 92a, 93a are formed at corresponding positions between the outer peripheral surface of the holder 92 and the inner peripheral surface of the gear 93, and the accommodating portion 9 formed by the opposing concave portions 92a, 93a.
4, a damper spring 95 is provided. A holding plate 96 for preventing the damper spring 95 from being detached from the accommodation portion 94 is fixed to the holder 92 by a rivet 97. Then, the gear 93 rotates together with the holder 92 via the damper spring 95.

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 damper spring 95. When the crankshaft rotates, torque fluctuations occur in the rotation direction of the crankshaft.
When the rotation is transmitted to the holder 92 from the damper spring 9
5 expands and contracts and absorbs. Therefore, transmission of torque fluctuations of the crankshaft to the balance shaft 91 of the balance device is prevented.

Japanese Unexamined Utility Model Publication No. 59-42335 discloses an anti-torque balancer provided with a rotating body having a large moment of inertia rotating in a direction opposite to the rotation direction of an engine. There is disclosed an anti-torque balancer in which a rubber cushioning member is interposed between a rotating body and an integrated driven shaft, and a clutch mechanism for directly driving the driven wheel and the driven shaft at a predetermined rotational speed or less is provided.

[0008]

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 Japanese Patent No. 47, it is possible to prevent the torque fluctuation of the crankshaft from being transmitted to the balance device side.

However, since there is no particular member for regulating the relative rotation between the holder 92 and the gear 93,
When a large torque acts on the gear 93, the holder 92
The gear 93 and the gear 93 rotate relative to each other until the coil of the damper spring 95 comes into close contact with the gear 93, and then the relative rotation is regulated, so that the two rotate together. In such a state, the end portion of the damper spring 95 comes into strong contact with the inner surfaces of the concave portions 92a and 93a that define the housing portion 94, and the inner surfaces are worn, leading to a reduction in the strength of the gear 93.
Further, a force greater than the elastic limit is applied to the damper spring 95, and if such a contraction is repeated, the damper spring 95 deteriorates early.

[0010] If the damper spring 95 is lengthened to widen the relative rotatable range, it is possible to prevent the damper spring 95 from contracting to the elastic limit. However, it is necessary to enlarge the accommodating portion 94, and the holder 92 and the gear In order to maintain the strength of 93, it is necessary to enlarge the holder 92 and the gear 93, and the increase in the size of the holder 92 and the gear 93 due to the increase in the thickness in the radial direction cannot be ignored.

Further, the anti-torque balancer disclosed in Japanese Utility Model Laid-Open No. 59-43335 discloses that a clutch mechanism for directly driving a driven wheel and a driven shaft at a predetermined rotational speed or less is provided. However, this clutch mechanism prevents the damper mechanism from operating when the engine is rotating at a low speed. Even when this mechanism is applied to a driving force transmission device, the holder 92 and the gear are not affected while the damper mechanism is operating. It is not possible to regulate the relative rotation of 93 to less than a predetermined amount.

Further, in the conventional damper mechanism, since the damper spring is arranged at a point-symmetric position, the damper mechanism does not play a part of the role of the unbalance mass of the balance shaft.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a first object of the present invention is to prevent a damper spring from deteriorating at an early stage and to provide a balance shaft when applied to a balance device. An object of the present invention is to provide a damper device capable of reducing the unbalance mass. Another object of the present invention is to provide a driving force transmission device for an internal combustion engine that can reduce the size of a balance device and prevent early deterioration of a damper spring.

[0014]

In order to achieve the first object, according to the first aspect of the present invention, the first spring holder and the first spring holder are coaxially rotated relative to each other. A second spring holder that is disposed so as to be capable of being provided, and a damper spring that is provided between the first and second spring holders and that transmits the rotational force of one spring holder to the other spring holder between the two spring holders. A regulating portion provided between the spring holders to regulate the relative rotation of the spring holders by a predetermined amount or more in the contraction direction of the damper spring, wherein the center of gravity of the regulating portion and the entire damper spring is The position and weight of the restricting portion were set so as to be deviated from the rotation center of the holder.

[0015] In order to achieve the second object, a second aspect is provided.
In the invention described in the above, a driving force transmission device for an internal combustion engine provided with a balance device that cancels the inertial force of the piston acting on the crankshaft, which is located on the same axis and rotatable about a coaxial line First and second driving force transmitting members, and a buffer mechanism for connecting the first and second driving force transmitting members to each other in the direction of rotation thereof, wherein the rotation of the first driving force transmitting members is A restricting portion that transmits the driving force to the second driving force transmitting member via a damper spring provided in the shock absorbing mechanism and that controls the shrinkage of the damper spring by a predetermined amount or more by the first and second drive. In addition to being disposed between the transmission members, the restricting portion is provided at a position capable of playing a part of an unbalance mass provided on the balance shaft of the balance device.

According to a third aspect of the present invention, in the second aspect of the invention, the damper device according to the first aspect is used as the buffer mechanism, and the first and second damper devices are used.
Is attached to one of the first and second driving force transmitting members, and the other spring holder is attached to the other driving force transmitting member.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the first driving force transmitting member is attached to the balance shaft so as to be relatively rotatable, and the second driving force transmitting member is The first spring holder is fixed to the first driving force transmitting member, and the second spring holder is fixed to the second driving force transmitting member. .

In the damper device according to the first aspect of the present invention, the two spring holders are used coaxially and relatively rotatably. The rotational force of one spring holder is transmitted to the other spring holder via a damper spring. When the rotational force is transmitted, the damper spring contracts. If there is no restricting portion that regulates the relative rotation between the two spring holders, if the compression force acting on the damper spring is large, the relative position between the two spring holders will be reduced when the damper spring contracts to a state where it cannot be further contracted. The rotation is stopped. In this state, a force exceeding the elastic limit acts on the damper spring, and if such contraction is repeated, the damper spring deteriorates early. In addition, the wear of the holder becomes faster. However, the presence of the restricting portion restricts the relative rotation of the two spring holders in the contracting direction of the damper spring when the damper spring contracts to a predetermined amount. As a result, early deterioration of the damper spring is suppressed, and early wear of each spring holder is also suppressed. Further, since the position and weight of the restricting portion are set such that the center of gravity of the restricting portion and each damper spring as a whole is deviated with respect to the rotation axis of the both holders, the damper device of the present invention is used to balance the internal combustion engine When used in the device, the unbalance mass provided on the balance shaft can be reduced.

According to the second aspect of the invention, when the rotation of the first driving force transmitting member is transmitted to the second driving force transmitting member via the damper spring, the damper spring contracts. When the amount of contraction of the damper spring exceeds a predetermined amount, an excessive force is applied to the damper spring, so that the damper spring is deteriorated early and the contact portion with the damper spring is abraded early. However, due to the presence of the restricting portion, the contraction of the damper spring by a predetermined amount or more is restricted, and the above inconvenience is avoided. Further, since the regulating portion plays a part of the role of the unbalance mass provided on the balance shaft of the balance device, the unbalance mass can be reduced.

According to a third aspect of the present invention, in the second aspect of the invention, the damper device according to the first aspect is used for the buffer mechanism. According to a fourth aspect of the present invention, in the third aspect of the present invention, the second driving force transmitting member rotates integrally with the balance shaft. The first driving force transmission member is rotatable relative to the balance shaft, and rotation of the first driving force transmission member is transmitted to the second driving force transmission via the first spring holder, the damper spring, and the second spring holder. Transmitted to the member.

[0021]

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

As shown in FIG. 3, 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 crankshaft 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. The crankshaft 11 has bevels 13
A metal crankshaft gear 13 having a is fixed to the shaft 11 so as to be integrally rotatable therewith.

At the lower end of the cylinder block 12, a balance device 14 for canceling the inertial force of the piston acting in the direction of movement of the piston during operation of the engine is mounted. The balance device 14 includes a pair of housings 1.
First and second balance shafts (only the first balance shaft is shown in FIG. 3) 16, 1 rotatably supported in a state parallel to the crankshaft 11 between 5a and 15b.
7 is provided. The first and second balance shafts 16 and 17 are provided with an unbalance mass 18 eccentric to the axes of the shafts 16 and 17.

First and second balance shafts 16, 1
7, the rotation of the crankshaft 11 is transmitted through the crankshaft gear 13 and the driving force transmission device 19. When the rotation of the crankshaft 11 is transmitted to the first and second balance shafts 16 and 17 as described above, the shafts 11, 16 and 17 rotate in synchronization. Then, the first and second balance shafts 1
When the shafts 6 and 17 rotate, the unbalance mass 18 rotates together with the shafts 16 and 17 and reciprocates in the moving direction of the piston (vertical direction in the figure).

Therefore, the unbalanced mass 18 is reciprocally displaced by the synchronized rotation of the crankshaft 11 and the first and second balance shafts 16 and 17, and the inertial force of the unbalanced mass 18 moves in the direction of movement of the piston ( (Vertical direction in the figure). The mass of the unbalance mass 18 and the mounting positions of the shafts 16 and 17 in the circumferential direction are adjusted in advance so that the inertial force of the unbalance mass 18 and the inertial force of the piston cancel each other to become “0”. ing.

Next, a detailed structure of the driving force transmitting device 19 and a damper device incorporated in the driving force transmitting device 19 will be described. As shown in FIG. 1, FIG. 3 and FIG. 4, the driving force transmission device 19 controls the rotation of the crankshaft 11 to a first position.
Gear mechanism 20 for transmitting to the balance shaft 16
It has. The gear mechanism 20 is connected to first and second gears 21 and 22 provided in parallel on the axis of the first balance shaft 16, and a buffer for connecting the gears 21 and 22 in a rotational direction about the axis. And a damper device 23 as a mechanism.

A first gear 21 as a first driving force transmitting member is attached to the first balance shaft 16 so as to be rotatable relative to the first balance shaft 16. Have. A plurality of fitting holes 21b are formed in the first gear.

The second gear 22 as a second driving force transmitting member has beveled teeth 22a on the outer periphery, and is provided on the first balance shaft 16 so as to be integrally rotatable. In the present embodiment, the second gear 22 is formed integrally with the first balance shaft 16. On the surface of the second gear 22 facing the first gear 21, a columnar accommodating portion 24 having a step is formed. The accommodation portion 24 has a large diameter on the side close to the first gear 21.

The damper device 23 includes a first spring holder 25, a second spring holder 26, and a damper for transmitting the rotational force of one spring holder 25 to the other spring holder 26 between the two spring holders 25, 26. And a spring 27.

As shown in FIG. 5, the first spring holder 25 is formed in a cylindrical shape with a bottom, and a hole 25b through which the first balance shaft 16 can be loosely inserted is formed at the center of the bottom wall 25a. The first spring holder 25 includes a peripheral wall 25.
The height of c is formed to be substantially the same as the outer diameter of the damper spring 27, and four projections 29 projecting toward the center of the spring holder 25 are provided on the inside at equal intervals in the circumferential direction. . Each of the protrusions 29 is formed in a substantially isosceles right triangle shape, and is disposed such that the oblique side faces the outside of the first spring holder 25 so that the mutually facing surfaces of the adjacent protrusions 29 are parallel. Is formed. Then, as shown in FIG. 2, the damper spring 27 is housed between the end faces 29 a of the projection 29 facing each other. Each projection 29 is formed with an arc-shaped guide groove 29 b centered on the center of the first spring holder 25.

As shown in FIGS. 1 and 5, a fitting hole 30 corresponding to the fitting hole 21b of the first gear 21 is formed in the bottom wall 25a of the first spring holder 25. First
The spring holder 25 is provided with a fixing pin 31 fitted and fixed to the fitting holes 21b and 30 in a state where the bottom wall 25a is in contact with the surface of the first gear 21 facing the second gear 22.
Relative to the first balance shaft 16 so as to be rotatable,
The first gear 21 is fixed so as to be integrally rotatable.

As shown in FIG. 5, the second spring holder 26 has a plate 32 formed in a ring shape and a pair of locking projections protruding from the surface of the plate 32 facing the first spring holder 25. It is composed of a piece 33 and a locking piece 35 having a stopper 34 at the center, which constitutes a regulating portion. The locking pieces 33 and 35 are formed in an arc shape having the same curvature as the guide groove 29b of the projection 29, and are formed at positions corresponding to the guide grooves 29b. As shown in FIGS. 1 and 2, the second spring holder 26 has a state in which the plate 32 is accommodated in the small-diameter portion of the accommodation portion 24 and the locking pieces 33 and 35 are loosely inserted into the guide grooves 29 b. Are fixed to the second gear 22 so as to be integrally rotatable by fixing means (not shown).

The second spring holder 26 is different from the first spring holder 25 in the first spring holder 2.
5 is disposed coaxially and relatively rotatable with respect to a first balance shaft 16 to which the first balance shaft 5 is integrally rotatably fixed. Then, the second spring holder 26 is attached to the stopper 3
Until the position at which the projection 4 abuts on the end surface 29a of the projection 29, the first
When the stopper 34 is in contact with the end surface 29a, the relative rotation of the damper spring 27 in the contraction direction is restricted. In the present embodiment, the stopper 34 and the end surface 29a with which the stopper 34 abuts constitute the restricting portion 28. That is, the restricting portion 28 is provided with the two spring holders 25 and 2 of a predetermined amount or more in the contraction direction of the damper spring 27.
6 relative rotation.

The damper spring 27 comprises a linear coil spring and is provided between the spring holders 25 and 26. As shown in FIG. 2, when no rotational force is applied to the first spring holder 25, both ends of the damper spring 27 are in contact with both end surfaces 29 a of the projection 29 and the engaging pieces 33, 35. Are held so as to be engaged with the end faces 33a and 35a of the first and second end portions. Three damper springs 27 are provided, and are arranged symmetrically with respect to a straight line passing through the centers of the damper spring 27 and the stopper 34 arranged at the center. Also,
The position and weight of the stopper 34 are set so that the center of gravity of the stopper 34 and the entire damper spring 27 is deviated from the center of rotation of the spring holders 25 and 26. The second spring holder 26 is arranged so that the stopper 34 is located at a position where the stopper 34 can play a part of the role of the unbalance mass 18 provided on the first balance shaft 16. It is fixed to. In the present embodiment, the stopper 34 is the first balance shaft 1
The second spring holder 26 is located at a position corresponding to the bulging side of the unbalance mass 18 provided on the second spring holder 26.
Are fixed to the second gear 22.

The gear mechanism 20 configured as described above
The first gear 21 meshes with the crankshaft gear 13 attached to the crankshaft 11, and the second gear 22 meshes with the third gear 36 as shown in FIG. The third gear 36 is integrally rotatably fixed to a second balance shaft 17 provided in parallel with the first balance shaft 16. In the present embodiment, the driving force transmission device 19 is configured by the third gear 36 and the gear mechanism 22.

Next, the operation of the driving force transmission device 19 configured as described above will be described. When the crankshaft 11 rotates by the reciprocating movement of the piston, the rotation of the shaft 11 is transmitted to the first gear 21 of the gear mechanism 20 in the driving force transmission device 19 via the crankshaft gear 13. The rotation transmitted from the crankshaft gear 13 to the first gear 21 causes the first gear 21 to rotate about the axis of the first balance shaft 16 with respect to the first balance shaft 16. Further, when the first gear 21 rotates, the rotation is transmitted to the second gear 22 and the third gear 36 via the damper device 23 in the gear mechanism 20. Then, the crankshaft 11 and the first and second balance shafts 1
As a result, the inertia force of the piston is canceled by the inertia force of the unbalance mass 18.

When the rotation of the first gear 21 is transmitted to the second gear 22 via the damper device 23, the two gears 21,
22 rotates relative to each other, and both spring holders 25 and 26 also rotate relative to the axis of the first balance shaft 16. Then, the distance between the end surface 29a of the protrusion 29 on the rotation direction side of the first spring holder 25 and the end surfaces 33a, 35a of the locking pieces 33, 35 facing the end surface 29a is reduced. As a result, each damper spring 27 is compressed.

Crankshaft 1 by reciprocation of piston
In one rotation, torque fluctuation occurs in the rotation torque of the shaft 11. However, even if the torque fluctuation causes the first gear 21 to fluctuate in the direction of relative rotation with respect to the second gear 22, the relative rotation of the first gear 21 by the expansion and contraction of the damper spring 27. The change in the direction is not transmitted to the second gear 22.

The expansion and contraction of the damper spring 27 also plays a role of absorbing a shock when the rotation is transmitted from the crankshaft gear 13 to the first gear 21. That is, the shock applied from the crankshaft gear 13 to the first gear 21 during the rotation transmission is reduced by the expansion and contraction of the damper spring 27.

When the damper spring 27 is compressed,
If there is no restricting portion 28 for restricting the relative rotation between the spring holders 25 and 26, when the compressive force acting on the damper spring 27 is large, the damper spring 27 is contracted to a state where it cannot be further contracted. , The relative rotation of both spring holders 25 and 26 is stopped. In this state, a force exceeding the elastic limit acts on the damper spring 27, and when such contraction is repeated, the damper spring 2
7 deteriorates early. Also, both spring holders 25,
26 wears faster.

However, due to the presence of the restricting portion 28, the stoppers 34 and the end surfaces 29a of the protruding portions 29 come into contact with each other when the damper spring 27 contracts to a predetermined amount, as shown in FIG. The contact and the relative rotation of the damper spring 27 in the contraction direction are restricted.
As a result, early deterioration of the damper spring 27 is suppressed, and early wear of both spring holders 25 and 26 is also suppressed.

Further, the center of gravity of the entire regulating portion 28 and each of the damper springs 27 is deviated with respect to the axis of the first balance shaft 16, and the regulating portion 28 takes a part of the role of the unbalance mass 18. Since it is provided, the unbalance mass 18 can be reduced accordingly. Specifically, the dimension L of the unbalance mass 18 in FIG. 1 can be reduced.

According to the embodiment described above, the following effects can be obtained. (1) The first and second spring holders 25 and 26 holding the damper spring 27 of the damper device 23 regulate the relative rotation of the damper spring 27 in the contraction direction by a predetermined amount or more by the action of the regulating portion 28. Is done. Therefore, the force exceeding the elastic limit is prevented from acting on the damper spring 27, and the damper spring 27 is prevented from being deteriorated at an early stage or the spring holders 25 and 26 are quickly worn.

(2) The center of gravity of the regulating portion 28 of the damper device 23 and the entire damper spring 27 is configured to be deviated from the axis of the first balance shaft 16, and the regulating portion 28 of the unbalance mass 18 Because it is provided at a position that plays a part of the role, the unbalanced mass 1
8 can be reduced. As a result, the size of the balance device 14 can be reduced.

(3) Since the damper device 23 independently constitutes one unit, by incorporating the damper device 23 into the gear mechanism 20 of the power transmission device 19, the effects of (1) and (2) can be obtained. And can be easily applied to existing balancing devices.

(4) Most of the portion (the stopper 3) of the regulating portion 28 which plays a part of the role of the unbalance mass 18
4) is fixed to the first balance shaft 16 side.
Of the spring holder 26. Therefore, the setting of the mounting position of the restricting portion 18 of the damper device 23 is simplified.

(5) Since the damper spring 27 of the damper device 23 is not arranged between the peripheral surfaces of the spring holders 25 and 26 but is arranged between the surfaces facing each other in the axial direction, it has the same length. When the damper spring 27 is used, the outer diameter of the spring holder can be reduced.
Therefore, the size of the balance device 14 can be further reduced.

The embodiment is not limited to the above, and can be modified as follows, for example. Instead of providing the unbalance mass 18 at one place, as shown in FIG. 7, the unbalance mass 18 may be provided separately on both sides of the gear mechanism 20.

The second gear 22 or the unbalance mass 18 is formed separately from the first balance shaft 16;
It may be fixed to the first balance shaft 16 so as to be integrally rotatable. In this case, the processing of the first balance shaft 16 and the second gear 22 is simplified.

When the first balance shaft 16 rotates, the ends of the locking pieces 33 and 35 which act to press the damper spring 27 when the first balance shaft 16 rotates, as shown in FIG. Square engaging portions 33b and 35b having sides longer than the diameter are provided. Further, a concave portion using an engaging portion is formed in the protrusion 29. In this case, one end of the damper spring 27 can always abut on the engaging portions 33b, 35b in a stable state.
7 stabilizes the damper action.

The second spring holder 26 may be formed of a material having a higher density than the unbalance mass 18.
Also, instead of forming the second spring holder 26 entirely of the same material, the side corresponding to the stopper 34 and the locking piece 35 is formed of a material having a higher density than the unbalance mass 18 and the other portions are formed of the unbalance mass. It is formed of a material having a density lower than 18. In these cases, as compared with the case where the entire second spring holder 26 is formed of a material having the same density as that of the unbalanced mass 18, the rate at which the stopper 34 and the like play the role of the unbalanced mass 18 can be increased. 18 can be made smaller.

The first spring holder 25 is formed integrally with the first gear 21 or the second spring holder 2
6 may be formed integrally with the second gear 22. In this case, each spring holder 25, 26 is
No need to assemble to

In the present embodiment, three damper springs 27 are provided in the damper device 23.
It may be appropriately changed to one or one. In this case, according to the number of the damper springs 27, the number and shape of the protrusions 29 and the numbers and shapes of the locking pieces 33 and 35 are also changed. In any case, the damper spring 27 is disposed at a position symmetrical with respect to a straight line passing through the center of the stopper 34 and the center of the axis on which the damper device 23 is mounted. If the number of the damper springs 27 is reduced, the assembling effort is simplified.

As the damper spring 27, a coil spring curved with substantially the same curvature as the locking pieces 33, 35 may be used instead of a linear coil spring. In this case, the end surface 29a of the protruding portion 29 for holding the damper spring 27 and the end surfaces 33a, 35a of the locking pieces 33, 35 are formed so as to be located on a plane passing through the centers of the spring holders 25, 26. With this configuration, the posture of the damper spring 27 is stabilized when the damper spring 27 expands and contracts with the relative rotation of the spring holders 25 and 26.

Instead of disposing the damper spring 27 between the surfaces of the spring holders 25 and 26 facing each other in the axial direction, the two spring holders 25 and 26 may be replaced by a damper device such as a damper device disclosed in Japanese Utility Model Laid-Open No. 106647/1986. Holder 2
It is good also as a structure arrange | positioned between 5 and 26 peripheral surfaces.

The damper device 23 is connected to the crankshaft 11
It may be attached to. For example, crankshaft gear 1
3 is disposed near the end of the crankshaft 11, and the first spring holder 25 of the damper device 23 is fixed to the crankshaft gear 13. Further, a gear is rotatably supported on the crankshaft 11, and the second spring holder 26 is fixed to the gear. Then, the gear is meshed with a gear fixed to the balance shaft 16.

In this embodiment, the balance device 14 including the two balance shafts 16 and 17 has been exemplified.
The number of balance shafts may be appropriately changed to one or three or more according to the number of cylinders of the engine.

In this embodiment, the gears 21, 22, and 36 have been exemplified as the driving force transmitting members. However, sprockets, pulleys, and the like may be used 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 damper device 23 is applied to the balance device 14 of the driving force transmitting device 19 of the engine. However, the damper device may be applied to other devices. Also,
The engine is not limited to an automobile engine, and may be applied to another engine such as a marine engine.

The technical ideas other than those described in the claims which can be grasped from the embodiment will be described below together with their effects. (1) In the invention according to any one of claims 2 to 4, the regulating portion is formed of a material having a higher density than the unbalance mass. In this case, the size of the unbalance mass can be further reduced.

[0061]

As described above in detail, according to the first aspect of the present invention, it is possible to prevent the damper spring from being deteriorated at an early stage.
The unbalance mass provided on the balance shaft can be reduced.

According to the present invention, the size of the balance device can be reduced and the damper spring can be prevented from being deteriorated early. According to the third aspect of the present invention, the present invention can be easily applied to an existing balance device.

According to the fourth aspect of the present invention, the setting of the mounting position of the regulating portion of the damper device is simplified.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a driving force transmission device according to an embodiment.

FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1 with gears omitted.

FIG. 3 is a schematic side view showing an engine including a driving force transmission device.

FIG. 4 is a schematic front view showing a connection mode between a crankshaft and a balance device.

FIG. 5 is an exploded perspective view of the damper device.

FIG. 6 is a sectional view showing a state in which both balance holders are relatively rotated.

FIG. 7 is a cross-sectional view corresponding to FIG. 1 of another embodiment.

FIG. 8 is a sectional view of another embodiment corresponding to FIG. 6;

FIG. 9 is a partially cutaway front view showing a conventional example of a driving force transmission device.

[Explanation of symbols]

11 ... crankshaft, 14 ... balance device, 16 ...
1st balance shaft, 18 ... unbalance mass, 1
9: Driving force transmitting device, 21: First gear as first driving force transmitting member, 22: Second gear as second driving force transmitting member, 23: Damper device as buffer mechanism, 25
... first spring holder, 26 ... second spring holder, 27 ... damper spring, 28 ... restrictor, 34 ...
Stopper that constitutes the regulation part.

Claims (4)

[Claims] A first spring holder, a second spring holder arranged coaxially and relatively rotatable with respect to the first spring holder, and a first spring holder and a second spring holder. A damper spring provided between the two spring holders for transmitting the rotational force of one spring holder to the other spring holder; and both holders provided between the two spring holders and having a predetermined amount or more in a contraction direction of the damper spring. A restricting portion for restricting relative rotation of the holder, and the position and weight of the restricting portion are set such that the center of gravity of the restricting portion and the entire damper spring deviates from the rotation center of the both holders. And a damper device. 2. A driving force transmitting device for an internal combustion engine having a balance device for canceling an inertial force of a piston acting on a crankshaft, wherein the driving force transmitting device is located on the same axis and is rotatable about a coaxial line. First and second driving force transmitting members; and a buffer mechanism for connecting the first and second driving force transmitting members to each other in a rotational direction thereof, wherein the first driving force transmitting member is configured to buffer the rotation of the first driving force transmitting member. The first and second drive transmissions are transmitted to a second driving force transmission member via a damper spring provided in the mechanism, and the first and second drive transmissions are provided to the buffer mechanism by a restriction section for restricting the damper spring from contracting by a predetermined amount or more. In addition to being disposed between the members, the restricting portion is provided at a position capable of playing a part of an unbalance mass provided on a balance shaft of the balance device. The internal combustion engine of the driving force transmission apparatus. 3. The damper device according to claim 1, wherein one of the first and second spring holders of the damper device is connected to one of the first and second driving force transmitting members. 3. The driving force transmission device for an internal combustion engine according to claim 2, wherein the other spring holder is attached to the other driving force transmission member. 4. The first driving force transmitting member is attached to the balance shaft so as to be relatively rotatable, the second driving force transmitting member is provided on the balance shaft so as to be integrally rotatable, and the first spring The driving force transmission device for an internal combustion engine according to claim 3, wherein a holder is fixed to the first driving force transmission member, and the second spring holder is fixed to the second driving force transmission member.