JP2002195386A - Gear mechanism for power transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear mechanism for a power transmission system without generating problems on impulsive sound and durability in a region of large rotation fluctuation and without making tooth strike noise conspicuous in also a region of small rotation fluctuation such as an idle rotation region. SOLUTION: When rotation fluctuation is large, locking parts 61c and 62c are pressed into a locking state by an outside inner peripheral wall 56a and an inside inner wall peripheral 56b of a recessed part 56. When rotation fluctuation is small, they are separated in a non-locking state. Therefore, a spring constant can be lowered since rotation fluctuation is small in the idle rotation region and resonance can be prevented and thereby rotation fluctuation can be suppressed to a small degree and tooth striking noise is relatively made inconspicuous. Since the spring constant can be made high since rotation fluctuation is large in regions except the idle rotation region, a damper mechanism 50 can be prevented from remarkably contracting. As a result, generation of impulsive sound from the damper mechanism 50 and lowering of durability of the damper mechanism 50 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission gear mechanism. In particular, in a power transmission system that transmits power between the rotating shafts by meshing a gear provided on the first rotating shaft with a gear provided on the second rotating shaft, one of the gears or Both relate to a gear mechanism of a power transmission system attached to a rotary shaft via a damper mechanism that generates a damper action by allowing relative rotation with respect to the rotary shaft.

[0002]

2. Description of the Related Art In an internal combustion engine, since a reciprocating portion such as a piston and a connecting rod generates an inertial force and an inertial couple, a balancer device is used to cancel them. In this balancer device, since the balance shaft is connected to the crankshaft side by gear engagement, rattling noise occurs between gears due to torque fluctuation on the crankshaft side.

A technique for preventing such rattling noise by providing a gear with a damper mechanism is disclosed in Japanese Patent Application Laid-Open No. HEI 11-1999.
No. 2290. In this damper mechanism, a spring is disposed between a spring stopper provided on a gear side and a spring stopper provided on a rotating shaft side. The expansion and contraction of the spring causes a damper action to prevent rattling noise due to rotation fluctuation.

[0004]

The spring disposed between the two spring stoppers as described above needs to cope with the rotation fluctuation in the entire operation range of the internal combustion engine.
That is, in an operation region where the maximum rotation fluctuation occurs (specifically, a high rotation region), the spring may largely contract, causing the springs to adhere to each other and collide with the spring stoppers. In such a case, a large impact may be applied to the damper mechanism, which may cause an impact sound and a problem in durability. Therefore, the spring constant of the spring needs to be sufficiently large.

[0005] However, when the rotation is adapted to the maximum rotation fluctuation, resonance occurs due to a high spring constant of the spring in a low rotation region such as an idle rotation region as shown by a solid line in FIG. There is a possibility that the rotation fluctuation increases and the rattling noise increases. In particular, in the idling rotation region, since the vibration noise of other mechanisms of the internal combustion engine is small, the rattling noise is relatively conspicuous, and the driver may feel uncomfortable.

For this purpose, measures to reduce the spring constant can be considered. In other words, when the spring constant is reduced, as shown by the broken line in FIG. 18, the resonance region is lower than the idle rotation region, so that the rotation fluctuation in the idle rotation region is suppressed low, and the rattling noise does not become relatively conspicuous. However, as described above, when the spring constant is low, in the high rotation region, the springs come into close contact with each other and the spring stoppers collide with each other, which may cause an impact sound and a problem in durability.

According to the present invention, there is provided a power transmission which does not cause an impact sound or a problem in durability in a region where rotation fluctuation is large, and has no rattling noise even in a region where rotation fluctuation is small such as an idle rotation region. It is intended to provide a system gear mechanism.

[0008]

The means for achieving the above object and the effects thereof will be described below. The gear mechanism of the power transmission system according to claim 1, wherein power is transmitted between the rotating shafts by meshing a gear provided on the first rotating shaft with a gear provided on the second rotating shaft. In the power transmission system to be performed, one or both of the gears is a gear mechanism of the power transmission system attached to the rotation shaft via a damper mechanism that generates a damper action by allowing relative rotation with respect to the rotation shaft, A spring constant varying means for varying a spring constant in a damper action of the damper mechanism is provided.

As described above, since the spring constant varying means varies the spring constant in the damper action of the damper mechanism, when applied to a power transmission system to a balance shaft of an internal combustion engine or the like, the spring constant is reduced in an idle rotation region. As a result, resonance can be prevented, so that rotation fluctuation can be suppressed to a small value, and rattling noise can be made inconspicuous. By increasing the spring constant in a region other than the idling rotation region, it is possible to prevent the configuration of the damper mechanism from being largely contracted, so that it is possible to prevent the generation of an impact sound and a decrease in durability.

According to a second aspect of the present invention, in the power transmission system gear mechanism according to the first aspect, the damper mechanism includes an elastic member that exerts a restoring force in a direction in which the gear and the rotating shaft relatively rotate. Thereby, a damper function is realized by expansion and contraction of the elastic member, and the spring constant variable means acts on the elastic member to change a spring constant in a damper function of the damper mechanism.

The damper mechanism may be a mechanism for realizing a damper action by the expansion and contraction of the elastic member. The spring constant can be varied by operating the spring constant varying means on the elastic member, so that the spring constant in the damper action of the damper mechanism can be varied. As a result, when applied to a power transmission system to a balance shaft of an internal combustion engine or the like, resonance can be prevented by reducing the spring constant of the elastic member in the idling rotation region, so that rotation fluctuation can be suppressed small, The rattling noise can be made inconspicuous. By increasing the spring constant in a region other than the idling rotation region, it is possible to prevent the configuration of the damper mechanism from being largely contracted, so that it is possible to prevent the generation of an impact sound and a decrease in durability.

According to a third aspect of the present invention, in the power transmission system gear mechanism according to the second aspect, the spring constant changing unit switches between allowing and prohibiting expansion and contraction of a part of the elastic member. The spring constant in the damper action of the damper mechanism is variable.

More specifically, the spring constant varying means lowers the spring constant by allowing a portion of the elastic member to expand and contract, and inhibits the spring constant from expanding and contracting a portion of the elastic member. May be increased. This makes it possible to change the spring constant in the damper action of the damper mechanism with a relatively simple configuration.

According to a fourth aspect of the present invention, in the power transmission system gear mechanism according to the third aspect, the spring constant varying means is provided at an intermediate position in the expansion and contraction direction of the elastic member, the gear side or the rotating shaft side. By providing one or more locking portions that can be locked to the, by locking the locking portion to a member on the gear side or the rotating shaft side according to the rotation speed or rotation fluctuation of the rotating shaft or gear, The spring constant in the damper action of the damper mechanism is variable.

As a configuration for switching between permitting and prohibiting the expansion and contraction of a part of the elastic member, a configuration in which the locking portion is provided on the elastic member can be adopted. Thus, if the locking portion is locked to a member on the gear side or the rotation shaft side, expansion and contraction of a part of the elastic member can be prohibited, and if the locking is released, expansion and contraction of a part of the elastic member can be allowed. Thus, the spring constant in the damper action of the damper mechanism can be made variable.

According to a fifth aspect of the present invention, in the power transmission system gear mechanism according to the fourth aspect, the locking portion has a friction locking surface, so that the rotation speed or rotation speed of the rotating shaft or the gear can be changed. Accordingly, when a member on the gear side or the rotating shaft side comes into contact, the member is locked by a frictional force.

As a method of locking the locking portion to a member on the gear side or the rotating shaft side, the locking portion is provided with a friction locking surface, so that when the locking portion comes into contact with a member on the gear side or the rotating shaft side, the frictional portion is frictionally locked. It can be locked by force. Accordingly, when the number of rotations or the rotation fluctuation of the rotating shaft or the gear is large, the friction locking surface of the locking portion comes into contact with the gear side or the rotating shaft side member, thereby expanding or contracting a part of the elastic member. Can be banned. As a result, the spring constant is increased, and when applied to a power transmission system to a balance shaft of an internal combustion engine or the like, it is possible to prevent the elastic member from being largely contracted outside the idle rotation region. In addition, when the number of rotations or rotation fluctuation of the rotating shaft or the gear is small, the friction locking surface of the locking portion is separated from the member on the gear side or the rotating shaft side, thereby allowing a part of the elastic member to expand and contract. Thus, resonance can be prevented in the idling rotation region.

According to a sixth aspect of the present invention, in the power transmission system gear mechanism according to the fifth aspect, an integral body of the elastic member and the locking portion is provided around the rotation shaft on the gear side or the rotation shaft side. The locking portion is pressed against the inner wall surface of the storage portion according to the number of rotations or rotation of a rotating shaft or a gear by being disposed in the circular arc-shaped storage portion. The stop is locked to the gear side or the rotating shaft side.

Since the integrated member of the elastic member and the locking portion is arranged in the arc-shaped storage portion, the elastic member is compressed in the storage portion depending on the number of rotations or the rotation fluctuation of the rotating shaft or the gear. In this case, the locking portion is strongly pressed to the outside of the arc-shaped storage portion. Further, when the elastic member is extended in the storage portion, an action of strongly pressing the locking portion to the inside of the arc-shaped storage portion is generated. Accordingly, the spring constant in the damper action of the damper mechanism can be made variable with a simple configuration according to the rotation speed or rotation fluctuation of the rotating shaft or gear.

According to a seventh aspect of the present invention, in the power transmission system gear mechanism according to the third aspect, the spring constant varying means includes a locking portion for locking the elastic member at an intermediate position in the expansion and contraction direction on the gear side. Alternatively, by providing one or more on the rotating shaft side, the locking portion is locked at an intermediate position in the expansion and contraction direction of the elastic member in accordance with the number of rotations or rotation fluctuation of the rotating shaft or gear, so that the damper mechanism is provided. Is characterized in that the spring constant in the damper action is variable.

As a configuration for switching between permitting and prohibiting the expansion and contraction of a part of the elastic member, a configuration in which the locking portion is provided on the gear side or the rotating shaft side can be adopted. Thus, if the locking portion is locked at an intermediate position of the elastic member in the expansion and contraction direction, expansion and contraction of a part of the elastic member can be prohibited,
When the locking is released, the expansion and contraction of a part of the elastic member can be allowed. Thus, the spring constant in the damper action of the damper mechanism can be made variable.

According to the eighth aspect of the present invention, in the power transmission gear mechanism according to any one of the first to seventh aspects, one of the rotary shafts is a crankshaft of the internal combustion engine, and the other rotary shaft is a balance shaft. There is a feature.

More specifically, such a configuration can be applied to a gear mechanism in a power transmission system between a crankshaft and a balance shaft of an internal combustion engine. Therefore, in the idling rotation region, resonance can be prevented by lowering the spring constant, so that rotation fluctuation can be suppressed to be small and rattling noise can be made inconspicuous. By increasing the spring constant in a region other than the idling rotation region, it is possible to prevent the configuration of the damper mechanism from being largely contracted, so that it is possible to prevent the generation of an impact sound and a decrease in durability.

According to a ninth aspect of the present invention, in the power transmission gear mechanism according to the first aspect, at least one tooth portion of one or both of the gears is made of resin. I do.

In particular, when resin is used for the gear teeth, a damper function is required by the damper mechanism from the viewpoint of the durability of the gear, so that the above-described functions and effects are particularly useful.

[0026]

[First Embodiment] FIG. 1 is a schematic diagram showing a side structure of a balancer device to which the above-described invention is applied, and FIG. 2 is a schematic diagram showing an arrangement of respective gears of the balancer device. FIG.

The present balancer device includes a crankshaft 20 as an engine output shaft which is supported by a cylinder block 11 and a crankcase 12 of an internal combustion engine, and a lower portion provided below the crankshaft 20 and parallel to the crankshaft 20. It has a first balance shaft 30 and a second balance shaft 40.

Each of these balance shafts 30, 40 is
It is supported by a housing 13 that covers the crankcase 12 and the lower part of the balancer device. Each of the balance shafts 30 and 40 is provided with a pair of unbalance weights 33 and 43, respectively.

The crankshaft 20 is provided with eight balance weights 22, one pair for each cylinder. The crankshaft 20 is provided with a crank gear 21 at a position adjacent to the middle one of the eight balance weights 22 so as to be integrally rotatable.

The first balance shaft 30 is provided with a first driven gear 31 meshed with the crank gear 21 and capable of rotating relative to the first balance shaft 30. The diameter of the first driven gear 31 is set equal to the radius of the crank gear 21.
Further, the first balance shaft 30 is provided with a counter gear 32 so as to be integrally rotatable. First driven gear 3
Numeral 1 is drivingly connected to a counter gear 32 via a damper mechanism 50 that allows its relative rotation.

On the other hand, the second balance shaft 40 has
The second driven gear 4 meshed with the counter gear 32 and rotatable integrally with the second balance shaft 40
1 is provided.

FIGS. 3 and 4 show the structure of the damper mechanism 50. FIG. FIG. 3 is a sectional view taken along line AA in FIG.
Shows cross-sectional structures along the line BB in FIG. As shown in FIG. 3, the first driven gear 31 has an annular inner peripheral portion 31 a provided coaxially with the first balance shaft 30 and rotatably provided relative to the first balance shaft 30.
And an outer peripheral portion 31b provided integrally rotatably on the outer periphery of the inner peripheral portion 31a and having teeth 31c formed on the outer periphery thereof. The teeth 31c of the outer peripheral portion 31b are meshed with teeth formed on the outer periphery of the crank gear 21 (FIG. 2).

The inner peripheral portion 31a of the first driven gear 31 is formed of a metal material such as iron. On the other hand, the outer peripheral portion 31
b is formed of, for example, a resin material made of a thermosetting resin such as polyaminoamide or phenol reinforced with an aramid fiber woven fabric. The second driven gear 41 has at least its teeth formed of the above-described resin material, similarly to the first driven gear 31. On the other hand, the crank gear 21 and the counter gear 32 are both formed of a metal material such as iron. Each of the gears 21, 31, 32, and 41 is a helical gear in which each tooth is formed in a helical shape as shown in FIG.

On the inner peripheral portion 31 a of the first driven gear 31, on the side opposite to the side facing the counter gear 32, the first balance shaft 30 is provided around the axis of the first balance shaft 30. A concave portion 53 having an inner diameter larger than the outer diameter of is formed. Therefore, when the first driven gear 31 is disposed on the first balance shaft 30, an annular space is formed between the outer peripheral surface of the first balance shaft 30 and the inner peripheral surface of the concave portion 53. Becomes
In the annular space, a pair of annular friction dampers 54 are arranged as damping members.

Each of the friction dampers 54 is formed of a metal sliding portion 54a which is in contact with the inner peripheral surface of the recess 53.
And an elastic portion 54b made of an elastic material such as a rubber material.
It is comprised including. The sliding portion 54 a is provided with the first balance shaft 30 over the entire circumference of the first balance shaft 30 by the elastic force generated in the elastic portion 54 b of the friction damper 54.
Is always urged against the inner peripheral surface of the concave portion 53 of the driven gear 31. Therefore, when the first driven gear 31 relatively rotates with respect to the first balance shaft 30 and the counter gear 32, the magnitude of the urging force between the sliding portion 54a and the inner peripheral surface of the concave portion 53 is large. A frictional force is generated according to the force, and the frictional force acts as a damping force for suppressing the relative rotation.

As described above, since the crank gear 21 and the first driven gear 31 are meshed with each other by the helical gear, when the first driven gear 31 rotates by receiving the torque of the crank gear 21, the first driven gear 31 rotates. One driven gear 31 slightly moves in the axial direction of the first balance shaft 30. For this reason, there is a concern that the first driven gear 31 vibrates in the axial direction due to fluctuations in the rotational force and the like, and noise is generated due to repeated contact with the first balance shaft 30. The frictional force of the friction damper 54 also acts as a damping force for damping the vibration of the first driven gear 31.

On the other hand, on the side of the counter gear 32 that faces the first driven gear 31, an arc-shaped concave portion 56 is provided over substantially the entire circumference around the axis of the first balance shaft 30. . Both ends of the concave portion 56 are closed by a counter gear side stopper 57. A driven gear side stopper 59 projecting from the side surface of the first driven gear 31 is inserted into the recess 56 at a phase position substantially opposed to the counter gear side stopper 57.

In the space between the counter gear side stopper 57 and the driven gear side stopper 59 in the concave portion 56, spring-like elastic members 61 and 62 are arranged, and at each end, the counter gear side stopper 57 and the driven It is connected to a gear-side stopper 59.

The spring-like elastic members 61 and 62 are connected at one end to a counter gear-side stopper 57 by a first spring portion 6.
1a, 62a, the second spring portions 61b, 62b connected at one end to the driven gear side stopper 59, and the first spring portions 61a, 6 at substantially the center of the spring-like elastic members 61, 62.
2a and 2nd spring parts 61b and 62b are provided with the locking parts 61c and 62c respectively connected. Here, the first spring portions 61a and 62a are formed of coil springs, each of which has a spring constant of K1 and a damping coefficient of C1.
It is one. The second spring portions 61b and 62b are also formed of coil springs, and have a spring constant of K2 and a damping coefficient of C2.

The combined spring constant K3 of the spring-like elastic members 61 and 62 as a whole is “K1 · K2 / (K1
+ K2) ", and the value of the composite spring constant K3 is the spring constant K
1, K2. Although K1 = K2 is set here, K1 <K2 may be set, or K1> K2 may be set.

FIGS. 5 and 6 show the gears 21, 31, and
32, 41 schematically show the relationship among the shafts 20, 30, 40 and the damper mechanism 50. With such a configuration of the balancer device of the internal combustion engine, the rotational force transmitted from the crankshaft 20 can be applied to the crank gear 21, the first driven gear 31, the spring-like elastic members 61 and 62 of the damper mechanism 50, and The power is transmitted to the first balance shaft 30 via the counter gear 32. At the same time, the rotational force is transmitted from the counter gear 32 to the second balance shaft 40 via the second driven gear 41. Note that “m1,” “m2,” and “m3” shown in FIG. 5 are the crankshaft 20, the first balance shaft 30, and the second balance shaft 40, respectively.
“C3” shown in FIG. 6 is an attenuation coefficient of the friction damper 54.

In such a configuration, when the rotational force F is input from the crankshaft 20 to the balancer device, the first driven gear 31 changes the first balance shaft 30 and the counter gear according to the rotation fluctuation of the crankshaft 20. 32. At this time, when the internal combustion engine is in an idle rotation region and the rotation fluctuation of the crankshaft 20 is small, the relative rotation amount between the first driven gear 31 and the first balance shaft 30 and the counter gear 32 becomes small. When the relative rotation amount is small as described above,
As illustrated in FIG. 7, when the driven gear side stopper 59 moves, for example, clockwise in the concave portion 56 of the counter gear 32, the spring-like elastic member 61 existing in the rotation direction of the driven gear side stopper 59 becomes , Driven gear side stopper 59
And the counter gear side stopper 57 is compressed. At this time, since the first spring portion 61a and the second spring portion 61b are both compressed, the spring constant of the spring-like elastic member 61 is “K
3 ". Further, the spring-like elastic member 62 existing on the opposite side of the rotation direction of the driven gear side stopper 59 is extended between the driven gear side stopper 59 and the counter gear side stopper 57. At this time, the first spring portion 61a and the second spring portion 61
Since b and b are both extended, the spring constant of the spring-like elastic member 62 becomes “K3”. When the driven gear side stopper 59 is relatively rotated to the opposite side, the spring-like elastic member 6
1 is extended, the first spring portion 61a and the second spring portion 61
Since b and b are both extended, the spring constant of the spring-like elastic member 61 is “K3”. The spring-like elastic member 62 is compressed, but the first spring portion 61a and the second spring portion 61b are both compressed, so that the spring constant of the spring-like elastic member 62 is "K3".

On the other hand, when the internal combustion engine is in an operation state other than the idle rotation range and the rotation fluctuation of the crankshaft 20 becomes large, the first driven gear 31, the first balance shaft 30, the counter gear 32 Relative rotation amount increases. As a result, the amplitude when the driven gear side stopper 59 moves within the concave portion 56 of the counter gear 32 tends to increase. For this reason, as illustrated in FIG.
The spring-like elastic member 61 existing in the rotation direction of the driven gear side stopper 59 is engaged with the locking portion 61 c when compressed between the driven gear side stopper 59 and the counter gear side stopper 57.
Is strongly pressed against the outer inner peripheral wall 56a of the recess 56. Also, when the spring-like elastic member 62 existing on the opposite side to the rotation direction of the driven gear side stopper 59 is extended between the driven gear side stopper 59 and the counter gear side stopper 57, the locking portion 62c The inner arc surface 62e is strongly pressed against the inner inner peripheral wall 56b of the recess 56. When the driven gear side stopper 59 is relatively rotated to the opposite side, the spring-like elastic member 61 is extended as illustrated in FIG. 9 and the inner arc surface 61 e of the locking portion 61 c is moved inside the concave portion 56. Press firmly against the inner peripheral wall 56b. In addition, the spring-like elastic member 62 is compressed and strongly presses the outer arc surface 62d of the locking portion 62c against the outer inner peripheral wall 56a of the concave portion 56.

Here, the outer inner peripheral wall 56a, the inner inner peripheral wall 56b of the concave portion 56 of the counter gear 32 and the locking portions 61c,
Outer arc surfaces 61d and 62d of 62c, inner arc surface 61
The e and 62e are provided with a lining for increasing a frictional force, for example, a lining used for a clutch plate or a brake shoe. Therefore, the counter gear 3
The outer circular surface 61 of the locking portions 61c, 62c is provided on the outer inner peripheral wall 56a or the inner inner peripheral wall 56b of the second concave portion 56.
When d and 62d or the inner arc surfaces 61e and 62e are strongly pressed, the locking portions 61c and 62c are locked to the outer inner peripheral wall 56a or the inner inner peripheral wall 56b of the concave portion 56, and
The relative rotation of the counter gear 32 in the recess 56 is stopped.

Therefore, when the rotational fluctuation of the crankshaft 20 increases and the relative rotation amount between the first driven gear 31 and the first balance shaft 30 and the counter gear 32 increases, the spring-like elastic member 61 is a second spring portion 61b
Only will perform the damper function. Therefore, the spring constant of the spring-like elastic member 61 is “K2 (> K3)”. Similarly, for the spring-like elastic member 62, the second spring portion 6
Since only 2b performs the damper function, the spring constant is "K
2 (> K3) ". That is, when the rotation fluctuation is low, the state is as shown in FIG. 6, but when the rotation fluctuation is high, the state changes to the state shown in FIG.

In the above-described configuration, the outer arc surfaces 61d, 62d and the inner arc surfaces 61e, 61e,
The combination of the locking portions 61c, 62c having the 62e and the outer inner peripheral wall 56a and the inner inner peripheral wall 56b of the concave portion 56 provided with the lining corresponds to a spring constant varying means.

According to the first embodiment described above, the following effects can be obtained. (I). As described above, the locking portions 61c and 62c are
The spring constant in the damper action of the damper mechanism 50 is made variable by being pressed against the outer inner peripheral wall 56a and the inner inner peripheral wall 56b to be in a locked state, or separated to be in an unlocked state. Therefore, the first embodiment
When applied to a balancer device of an internal combustion engine as
In the idling rotation region, since the rotation fluctuation is small, the spring constant can be reduced. As a result, resonance can be prevented as described with reference to FIG. 18, so that rotation fluctuation can be suppressed to a small value, and the rattling noise can be made relatively inconspicuous.

Since the spring constant can be increased outside the idling rotation region, the first damper mechanism 50
It is possible to prevent the spring portions 61a and 62a and the second spring portions 61b and 62b from contracting significantly. For this reason, it is possible to prevent the generation of the impact sound from the damper mechanism 50 and the reduction in the durability of the damper mechanism 50.

(B). The spring-like elastic members 61 and 62 are arranged in an arc-shaped concave portion 56. Accordingly, when the spring-like elastic members 61 and 62 are compressed in the concave portion 56 when the rotation fluctuation of the crankshaft 20 is large, the locking portion 6
1c and 62c exert an action of being strongly pressed toward the outer inner peripheral wall 56a side of the concave portion 56. Also, spring-like elastic members 61 and 62
Are extended, the locking portions 61c and 62c
Of the inner peripheral wall 56b.
With such a simple configuration, the spring constant of the damper mechanism 50 can be made variable according to the rotation fluctuation of the crankshaft 20.

(C). The teeth of both the first driven gear 31 and the second driven gear 41 are formed of a resin material. When such a resin gear is used, a damper function by the damper mechanism 50 is required from the viewpoint of the durability of the gear, so that the above-described functions and effects are particularly useful.

[Second Embodiment] FIGS. 11, 12, and 13 show a damper mechanism 150 according to a second embodiment.
FIG. 11 shows a cross-sectional structure taken along line CC of FIG.
13 shows a cross-sectional structure along the line DD in FIG. 11, and FIG.
1 shows respective cross-sectional structures along the line EE.
In the damper mechanism 150 according to the second embodiment, the configurations of the counter gear-side stopper 157, the driven gear-side stopper 159, and the spring-like elastic members 161 and 162 in the recess 156 of the counter gear 132 are the same as those of the above-described embodiment unless otherwise specified. Same as in the first mode. The difference from the damper mechanism 50 of the first embodiment is as follows.

That is, a hydraulic oil passage 170 is provided in the first balance shaft 130 in the axial direction at the center. The working oil path 170 is supplied with working oil pressure from a bearing 171 provided on the crankcase side.
This operating oil pressure is controlled by an electronic control unit (EC
U) is controlled according to the operating state of the internal combustion engine as described later.

A hydraulic oil path 172 is formed continuously from the hydraulic oil path 170. This hydraulic oil path 172 radially penetrates the first balance shaft 130 so as to be orthogonal to the hydraulic oil path 170. This hydraulic oil path 17
Cylinders 173 and 174 are formed at the respective distal end portions of 2. Pistons 175 and 176 are arranged in the cylinders 173 and 174, respectively. Piston 175,1
A spring 177,1 in an extended state is provided at the base end of 76.
Reference numeral 78 extends between the opening portion of the hydraulic oil passage 170. As a result, the pistons 175 and 176
Of the balance shaft 130 toward the center thereof. Further, fan-shaped pressing and locking portions 179 and 180 are formed at the tips of the pistons 175 and 176, respectively. At the tip of the cylinder 173, 174, the first balance shaft 130 is cut linearly in a direction orthogonal to the axial direction of the cylinder 173, 174, and the first balance shaft 130 is locked.
74a are formed. This locking part storage part 173a, 1
The fan-shaped pressing and locking portions 179 and 180 are housed in 74a.

Further, in the counter gear 132, the first balance shaft 1 of the inner peripheral side wall of the concave portion 156 is formed.
The slits 181 and 182 that are cut out in the circumferential direction are formed in portions of the 30 that face the locking portion storage portions 173a and 174a. This allows the pistons 175, 176
Is pushed out to the radially outer peripheral side, the fan-shaped pressing and locking portions 179 and 180 pass through the slits 181 and 182 and press the pressed portion 1 in the concave portion 156 of the counter gear 132.
61c and 162c.

With such a configuration, since the internal combustion engine is in the idle rotation region and the rotation fluctuation of the crankshaft is small, the relative rotation amount between the first driven gear 131, the first balance shaft 130, and the counter gear 132 is reduced. Consider a small state. When the ECU determines this state based on the rotational speed or rotational fluctuation of the crankshaft detected by the internal combustion engine rotational speed sensor, the ECU determines the hydraulic oil path 1
The operating oil supply valve (not shown) is adjusted so as to release the operating oil pressure of 70 and 172. As a result, as shown in FIG.
8, the first balance shaft 130 is drawn toward the center of the first balance shaft 130, and the fan-shaped pressing and locking portions 179 and 180 do not enter the recess 156 of the counter gear 132. Therefore, the concave portion 1 of the counter gear 132
When the driven gear-side stopper 159 moves relatively within 56, the spring-like elastic members 161 and 162 expand and contract between the driven gear-side stopper 159 and the counter gear-side stopper 157. At this time, the spring-like elastic members 161 and 162
First spring portions 161a, 162a and second spring portion 161
Since both b and 162b function as springs, the spring constant is “K3”.

When the internal combustion engine is out of the idle rotation region and the rotational fluctuation of the crankshaft increases, the relative rotation amount between the first driven gear 131, the first balance shaft 130 and the counter gear 132 increases. The ECU that detects this state based on the internal combustion engine rotation speed or rotation fluctuation,
By adjusting the hydraulic oil supply valve, the hydraulic oil paths 170 and 172 are adjusted.
Supply hydraulic pressure to This allows the piston 17
5, 176 moves to the outer peripheral side against the urging force of the springs 177, 178. As a result, as shown in FIG. 15, the fan-shaped pressing and locking portions 179 and 180 push the pressed portions 161c and 162c of the spring-like elastic members 161 and 162 to the outer peripheral side. Further, the fan-shaped pressing locking portions 179 and 180 are formed on the outer circular arc surfaces 161d and 162 of the pressed portions 161c and 162c.
d is the outer inner peripheral wall 15 of the concave portion 156 of the counter gear 132
6a.

Here, the outer inner peripheral wall 156a of the concave portion 156 and the outer circular arc surfaces 161d of the pressed portions 161c and 162c are formed.
162d is provided with a lining similar to that of the first embodiment. Therefore, when the outer arc surfaces 161d and 162d of the pressed parts 161c and 162c are strongly pressed against the outer inner peripheral wall 156a of the concave part 156, the pressed parts 161c and 162c stop the relative rotation in the concave part 156.

Therefore, when the relative rotation amount between the first driven gear 131 and the first balance shaft 130 increases, as shown in FIGS.
In No. 1, since only the second spring portion 161b performs the damper function, the spring constant is “K2 (> K3)”. Similarly, since only the second spring portion 162b of the spring-like elastic member 162 performs a damper function, the spring constant is “K2 (> K3)”.

In the above-described configuration, the pressed portion 1 having the outer circular arc surfaces 161d and 162d on which the lining is formed.
61c, 162c, concave portion 156 provided with lining
156a, hydraulic oil passages 170 and 172, cylinders 173 and 174, pistons 175 and 176, springs 177 and 178, fan-shaped pressing and locking portions 179 and 18, respectively.
The combination of 0, the slits 181, 182 and the ECU corresponds to a spring constant varying means.

According to the second embodiment described above, the following effects can be obtained. (I). The effects (a) and (c) of the first embodiment are obtained. (B). The fan-shaped pressing and locking portions 179 and 180 are provided in the first balance shaft 130, and can be locked by pressing the pressed portions 161c and 162c at a suitable timing by hydraulic control to switch the spring constant. Therefore, the spring constant can be reliably switched when necessary.

[Other Embodiments] In the second embodiment, the fan-shaped pressing and locking portions 179 and 180 are driven by hydraulic pressure to press the pressed portions 161c and 161c.
2c, the spring constant is switched by pressing it. In addition to this, an electromagnetic coil is provided along the outer peripheral surface or side surface of the counter gear 132, and the pressed portions 161c and 162c formed of a high magnetic permeability material are recessed. By being attracted to the bottom surface and the inner and outer peripheral surfaces in the 156, the pressed portions 161c and 16
The spring constant may be switched by locking 2c.

In the second embodiment, the pressed portion 161
The spring constants are switched by locking the first and second spring portions 161a and 162b without providing the pressed portions 161c and 162c.
May be formed as an integral coil spring, and a pin may be disposed so as to be able to advance and retreat with respect to an intermediate portion of the coil spring. As a result, the pin may be inserted into the middle portion of the coil spring and locked, and the spring constant may be switched by prohibiting expansion and contraction of a part of the coil spring.

In the first and second embodiments, the spring constant is set to 2
Although switched to the stage, three or more spring portions may be provided, and the spring portions may be connected by two or more locking portions or pressed portions. In particular, in the case of the second embodiment, by providing the same number of pistons as the pressed parts and by extruding the respective pistons to individually fix the pressed parts, the spring constant can be increased to three or more stages as necessary. You may switch.

In the first and second embodiments, the coil spring is used as the elastic member in which the restoring force acts in the direction in which the first driven gear, the first balance shaft and the counter gear rotate relative to each other. And a rubber elastic body may be used.

In the first and second embodiments, the damper mechanism is incorporated only in the counter gear, but may be incorporated in the crank gear. Further, it may be incorporated in both the counter gear and the crank gear. The damper mechanism may be incorporated in the first driven gear instead of the counter gear, or may be incorporated in both the counter gear and the first driven gear.

The embodiments of the present invention have been described above. However, it should be added that the embodiments of the present invention include the following embodiments. (1). In a power transmission system that transmits power between the rotating shafts by meshing a gear provided on the first rotating shaft with a gear provided on the second rotating shaft, one or both of the gears are provided. A gear mechanism of a power transmission system attached to the rotating shaft via a damper mechanism that produces a damper action by relative rotation with respect to the rotating shaft, wherein a spring constant in the damping action of the damper mechanism is set between a plurality of spring constants. A gear mechanism for a power transmission system, comprising a switchable spring constant variable means.

[Brief description of the drawings]

FIG. 1 is a schematic configuration explanatory view showing a side structure of a balancer device according to a first embodiment.

FIG. 2 is a schematic configuration perspective view showing an arrangement of each gear of the balancer device.

FIG. 3 is an explanatory sectional view of a damper mechanism provided on a first balance shaft of the balancer device.

FIG. 4 is a sectional structural explanatory view taken along the line BB of FIG. 3;

FIG. 5 is a schematic diagram schematically showing a meshing state of each gear of the gear mechanism according to the first embodiment.

FIG. 6 is a model diagram modeling the gear mechanism of the first embodiment at the time of low rotation fluctuation.

FIG. 7 is an operation explanatory view of the damper mechanism according to the first embodiment at the time of low rotation fluctuation.

FIG. 8 is a diagram illustrating the operation of the damper mechanism according to the first embodiment at the time of high rotation fluctuation.

FIG. 9 is a diagram illustrating the operation of the damper mechanism according to the first embodiment at the time of high rotation fluctuation.

FIG. 10 is a model diagram modeling the gear mechanism of the first embodiment at the time of high rotation fluctuation.

FIG. 11 is an explanatory sectional view of a damper mechanism provided on a first balance shaft according to the second embodiment.

FIG. 12 is a cross-sectional structure explanatory diagram along the line DD in FIG. 11;

FIG. 13 is an explanatory sectional view taken along line EE in FIG. 11;

FIG. 14 is an explanatory diagram of an operation of the damper mechanism according to the second embodiment at the time of low rotation fluctuation.

FIG. 15 is an operation explanatory view of the damper mechanism according to the second embodiment at the time of high rotation fluctuation.

FIG. 16 is an operation explanatory view of the damper mechanism according to the second embodiment at the time of high rotation fluctuation.

FIG. 17 is an explanatory diagram of an operation of the damper mechanism according to the second embodiment at the time of high rotation fluctuation.

FIG. 18 is a graph showing the relationship between the number of rotations and rotation fluctuation.

[Explanation of symbols]

11: cylinder block of internal combustion engine, 12: crankcase, 13: housing, 20: crankshaft, 2
DESCRIPTION OF SYMBOLS 1 ... Crank gear, 22 ... Balance weight, 30 ... First balance shaft, 31 ... First driven gear, 31a
... inner peripheral part, 31b ... outer peripheral part, 31c ... teeth, 32 ... counter gear, 33, 43 ... unbalanced weight, 40 ... second balance shaft, 41 ... second driven gear, 50 ...
Damper mechanism, 53 ... recess, 54 ... friction damper, 54a ... sliding part, 54b ... elastic part, 56 ... recess, 5
6a: outer inner peripheral wall, 56b: inner inner peripheral wall, 57: counter gear side stopper, 59: driven gear side stopper, 61 ...
Spring-like elastic members, 61a, 62a ... first spring portion, 61
b, 62b: second spring portion, 61c, 62c: locking portion, 6
1d, 62d: outer arc surface, 61e, 62e: inner arc surface, 62: spring-like elastic member, 130: first balance shaft, 131: first driven gear, 132: counter gear, 150: damper mechanism, 156 ... Recess, 156a ...
Outer inner peripheral wall, 157 ... Counter gear side stopper, 159
.., Driven gear side stoppers, 161, 162, spring-like elastic members, 161, spring-like elastic members, 161a, 162a, first spring portions, 161b, 162b, second spring portions, 161
c, 162c: pressed portion, 161d, 162d: outer circular arc surface, 170: hydraulic oil path, 171: bearing portion, 172 ...
Hydraulic oil path, 173, 174 ... cylinder, 173a, 1
74a: locking portion storage portion, 175, 176: piston, 1
77, 178: spring, 179, 180: fan-shaped pressing and locking portion, 181, 182: slit.

Claims (9)

[Claims] 1. A power transmission system for transmitting power between said rotating shafts by meshing a gear provided on a first rotating shaft with a gear provided on a second rotating shaft. Is a gear mechanism of a power transmission system attached to the rotary shaft via a damper mechanism that generates a damper action by allowing relative rotation with respect to the rotary shaft, wherein a spring constant in the damper action of the damper mechanism is provided. A gear mechanism for a power transmission system, comprising: a spring constant changing unit that changes a spring constant. 2. The damper mechanism according to claim 1, wherein the damper mechanism has an elastic member that exerts a restoring force in a direction in which the gear and the rotating shaft rotate relative to each other. A gear mechanism for a power transmission system, wherein the spring constant variable means acts on the elastic member to change a spring constant in a damper action of the damper mechanism. 3. The structure according to claim 2, wherein said spring constant changing means changes a spring constant in a damper action of said damper mechanism by switching between permitting and prohibiting expansion and contraction of a part of said elastic member. A power transmission gear mechanism. 4. A structure according to claim 3, wherein said spring constant varying means has one locking portion provided at an intermediate position in the expansion and contraction direction of said elastic member and lockable on a gear side or a rotating shaft side. Or by providing a plurality, by locking the locking portion to a member on the gear side or the rotation shaft side according to the number of rotations or rotation fluctuation of the rotation shaft or gear, the spring constant in the damper action of the damper mechanism is variable A power transmission gear mechanism, characterized in that: 5. The structure according to claim 4, wherein the locking portion has a friction locking surface, so that the locking portion can be attached to a member on the gear side or the rotation shaft side according to the rotation speed or rotation fluctuation of the rotation shaft or gear. A gear mechanism for a power transmission system, wherein the gear mechanism is locked by frictional force when contacted. 6. The structure according to claim 5, wherein the integral member of the elastic member and the locking portion is arranged in an arc-shaped storage portion provided around a rotation axis on a gear side or a rotation shaft side. As a result, the locking portion is pressed against the inner wall surface of the storage portion in accordance with the number of rotations or rotation fluctuation of the rotating shaft or the gear, and the locking portion is engaged with the gear or the rotating shaft by the frictional force at the time of pressing. A gear mechanism of a power transmission system characterized by stopping. 7. A structure according to claim 3, wherein said spring constant varying means includes one or more locking portions for locking at an intermediate position in the expansion and contraction direction of said elastic member on a gear side or a rotating shaft side. By locking the locking portion at an intermediate position in the expansion and contraction direction of the elastic member in accordance with the number of rotations or rotation fluctuation of the rotating shaft or the gear, the spring constant in the damper action of the damper mechanism is made variable. A power transmission gear mechanism characterized by the following: 8. The gear of a power transmission system according to claim 1, wherein one of the rotating shafts is a crankshaft of the internal combustion engine, and the other rotating shaft is a balance shaft. mechanism. 9. The arrangement according to claim 1, wherein at least one tooth portion of one or both of the gears comprises:
A power transmission gear mechanism characterized by being made of resin.