Damper mechanism

A damper mechanism 4 has an input rotary member 2, a hub flange 6, a large coil spring 8 and a friction generating mechanism 5. In a state in which the input rotary member 2 is twisted to one side in the rotational direction with respect to the hub flange 6, the friction member is pressed in the rotational direction against the hub flange 6 in a state in which at least part of the friction member has been elastically deformed in the relational direction, so that the friction member and the hub flange 6 function as an integral member in the rotational direction. In a state in which the input rotary member 2 is twisted to one side in the rotational direction with respect to the hub flange 6, the friction member is capable of relative rotation with respect to the hub flange.

TECHNICAL FIELD

The present invention relates to a damper mechanism, and more particularly relates to a damper mechanism for damping torsional vibration in a power transmission system.

BACKGROUND OF THE INVENTION

A clutch disk assembly used in a vehicle has a clutch function for engaging with and disengaging from a flywheel, and a damper function for absorbing and damping torsional vibration from the flywheel. Typical vibrations encountered with vehicles include idling noises (clattering), driving noises (acceleration and deceleration rattling, muffled noises), and tip-in and tip-out (low-frequency vibrations). The damper function eliminates these noises and vibrations.

Idling noises are those that sound like a clattering generated from the transmission when the shifter is put into neutral at a stoplight or the like, and the clutch pedal is released. The cause of these noises is that the engine torque is low, and torque fluctuates considerably during engine combustion near the engine idle speed. At such times the input gear and counter gear of the transmission clash.

Tip-in and tip-out (low-frequency vibrations) are large vibrations along the length of the chassis, produced when the accelerator pedal is suddenly pressed or released. If the power transmission system is low in stiffness, torque transmitted to the tires will be transmitted back from the tires, and this reverberation generates excessive torque at the tires, and this results in longitudinal vibration that strongly shakes the chassis back and forth transiently.

With idling noises, close to zero torque is problematic in the torsional characteristics of the clutch disk assembly, and it is therefore better for the torsional stiffness to be low. On the other hand, with tip-in and tip-out longitudinal vibration, the torsional characteristics of the clutch disk assembly must be made as solid as possible.

To solve the above problem, a clutch disk assembly has been proposed in which two-stage characteristics are attained by using two types of spring members. Here, torsional stiffness and hysteresis torque are kept low in the first stage of the torsional characteristics (the region of low torsion angle), which is effective in preventing noises during idling. Since the torsional stiffness and the hysteresis torque are kept high in the second stage of the torsional characteristics (the region of high torsion angle), tip-in and tip-out longitudinal vibration can be sufficiently damped.

Furthermore, there is a known damper mechanism with which minute torsional vibrations are effectively absorbed without operating a large friction mechanism for the second stage when the minute torsional vibrations are inputted, such as those caused by combustion fluctuation in the engine, in the second stage of the torsional characteristics.

In order for no large friction mechanism to be operated for the second stage when the minute torsional vibrations are inputted, such as those caused by combustion fluctuation in the engine, in the second stage of the torsional characteristics, it is necessary to ensure a gap of a specific angle in the rotational direction between a spring member with high torsional stiffness and the large friction mechanism in a state in which the spring member with high torsional stiffness has been compressed.

The angle of this gap in the rotational direction is very small (only about 0.2° to 1.0°, for example), and it is present at both the second stage on the positive side, where an input plate (input rotary member) is twisted to the drive side in the rotational direction (positive side) with respect to a spline hub (output rotary member), and the second stage on the negative side, where the twist is to the opposite side (negative side).

In particular, since the structure constituting the gap in the rotational direction was achieved in the past by the same mechanism at both the positive second stage and the negative second stage, this rotational direction gap was always generated on both the positive and negative sides of the torsional characteristics, and furthermore the magnitude of the angle was the same.

However, there are cases when it is preferable for the size of the rotational direction gap to be different on the positive and negative sides of the torsional characteristics, according to the characteristics of the vehicle, and it is also conceivable that it might even be preferable not to provide the above-mentioned rotational direction gap on one side of the torsional characteristics.

More specifically, on the negative side of the torsional characteristics, the above-mentioned rotational direction gap is necessary in order to lower the peak of vibration at the resonant rotational speed during deceleration. However, with a front-wheel drive vehicle, a resonance peak often remains in the practical rotational speed band, and if the above-mentioned rotational direction gap is ensured on the positive side of the torsional characteristics, this will adversely affect the noise and vibration performance near the resonant rotational speed.

In view of this, a damper mechanism has been proposed that has a gap for generating low hysteresis torque with respect to minute torsional vibration on only the negative side of the torsional characteristics (see Japanese Laid-Open Patent Application 2002-266943, for example).

However, to obtain a structure having a low hysteresis torque generating gap on just one side of the torsional characteristics, many extremely small friction washers or cone springs are necessary. Accordingly, the number of parts increases, and assembling the parts entails more labor. Specifically with a conventional damper mechanism, employing the above-mentioned structure drives up the manufacturing cost.

SUMMARY OF THE INVENTION

It is an object of the present invention to lower the manufacturing cost of a damper mechanism having a gap for generating low hysteresis torque with respect to the desired torsional vibration.

A damper mechanism according to a first aspect includes a first rotary member, a second rotary member, an elastic member, and a friction generating mechanism. The second rotary member is disposed rotatably within a range of a first angle with respect to the first rotary member. The elastic member elastically links the first and second rotating bodies in the rotational direction. The friction generating mechanism is disposed between the first and second rotating bodies and has a friction member that frictionally engages with the first rotary member. In a state in which the first rotary member is twisted to one side in the rotational direction with respect to the second rotary member, the friction member is pressed in the rotational direction against the second rotary member in a state in which at least part of the friction member has been elastically deformed in the rotational direction, so that the friction member and the second rotary member function as an integral member in the rotational direction. In a state in which the first rotary member is twisted to one side in the rotational direction with respect to the second rotary member, the friction member is capable of relative rotation with respect to the second rotary member within a range of a second angle that is smaller than the first angle.

With this damper mechanism, for example, when torque is inputted to one side in the rotational direction with respect to the first rotary member, the first rotary member rotates to one side in the rotational direction with respect to the second rotary member. As a result, the elastic member is compressed between the first rotary member and the second rotary member. Once the relative torsional angle of the first rotary member and the second rotary member reaches a first angle, the first rotary member and the second rotary member rotate integrally to one side in the rotational direction. Thus, torsional vibration inputted to the first rotary member is damped and absorbed, and torque is transmitted from the first rotary member to the second rotary member.

Here, in a state in which the first rotary member is twisted to one side in the rotational direction with respect to the second rotary member, the friction member is pressed in the rotational direction against the second rotary member in a state in which at least part of the friction member has been elastically deformed in the rotational direction. That is, the friction member and the second rotary member function as an integral member in the rotational direction under the elastic force of the friction member. Accordingly, when a minute torsional vibration is inputted to the first rotary member in this state, frictional resistance is generated between the first rotary member and the friction member, which generates hysteresis torque.

Meanwhile, in a state in which the first rotary member is twisted to one side in the rotational direction with respect to the second rotary member, the friction member is capable of relative rotation with respect to the second rotary member within a range of a second angle. Accordingly, no frictional resistance is generated between the first rotary member and the friction member, so no hysteresis torque is generated.

Thus, with this damper mechanism, a constitution can be achieved in which the elastic force of the friction member is utilized to generate hysteresis torque in all of the torsional vibration on one side of the torsional characteristics, and the generation of hysteresis torque can be prevented within a specific range of torsional angle on the other side of the torsional characteristics. Consequently, with this damper mechanism, the structure can be simplified and the manufacturing cost lowered.

A damper mechanism according to a second aspect is the damper mechanism according to the first aspect, wherein the friction member has a first annular component that is disposed rotatably with respect to the second rotary member within a range of a second angle that is smaller than the first angle, a second annular component that is disposed rotatably with respect to the first annular component, and a linking component that elastically links the first and second annular components in the circumferential direction. In a state in which the first rotary member is twisted to one side in the rotational direction with respect to the second rotary member, the linking component is elastically deformed in the rotational direction between the first annular component and the second annular component.

A damper mechanism according to a third aspect is the damper mechanism according to the second aspect, further including a third rotary member disposed so as to be capable of relative rotation with respect to the second rotary member. In a state in which the first rotary member is twisted to one side in the rotational direction with respect to the third rotary member, the first annular component is pushed to one side in the rotational direction by the second rotary member, and the second annular component is pushed to the other side in the rotational direction by the third rotary member.

A damper mechanism according to a fourth aspect is the damper mechanism according to the third aspect, wherein, in a neutral state in which no torque is inputted, the second rotary member is capable of rotating with respect to the third rotary member within a range of a third angle to one side in the rotational direction. In a state in which the relative rotation of the first annular component to the other side in the rotational direction with respect to the second rotary member is limited, the second annular component is capable of rotating by a fourth angle that is smaller than the third angle to one side in the rotational direction with respect to the second rotary member.

A damper mechanism according to a fifth aspect is the damper mechanism according to any of the second to fourth aspects, wherein the second rotary member has a hole passing through in the axial direction. The first annular component has a protrusion that protrudes in the axial direction and that is inserted into the hole. The second angle is maintained in the rotational direction between the hole and the protrusion.

A damper mechanism according to a sixth aspect is the damper mechanism according to any of the second to fifth aspects, wherein the second rotary member has an annular first main body component and a plurality of first inner peripheral teeth extending inward in the radial direction from the first main body component. The third rotary member has an annular second main body component and a plurality of outer peripheral teeth extending outward in the radial direction from the second main body component. The second annular component has a plurality of second inner peripheral teeth extending inward in the radial direction. In a neutral state in which no torque is inputted, the third angle is maintained in the rotational direction between the first inner peripheral teeth and the outer peripheral teeth. The fourth angle is maintained in the rotational direction between the second inner peripheral teeth and the outer peripheral teeth.

A damper mechanism according to a seventh aspect is the damper mechanism according to any of the second to sixth aspects, wherein the first annular component is disposed on the outer peripheral side of the second annular component. The linking component has a deformation component extending from the inner peripheral part of the first annular component to the outer peripheral part of the second annular component.

A damper mechanism according to an eighth aspect is the damper mechanism according to the seventh aspect, wherein the deformation component has a curved component that is curved in a wave shape.

A damper mechanism according to a ninth aspect is the damper mechanism according to any of the second to eighth aspects, wherein the linking component is formed integrally with the first and/or second annular component.

A damper mechanism according to a tenth invention is the damper mechanism according to any of the second to ninth aspects, wherein the friction member further has a friction plate that is disposed so as to be capable of relative movement in the axial direction and capable of rotating integrally with the first annular component, and that frictionally engages with the first rotary member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the damper mechanism pertaining to the present invention will now be described with reference to the drawings. An example of a clutch disk assembly in which a damper mechanism is installed will be described as an example here.

1. Overall Configuration of Clutch Disk Assembly

A clutch disk assembly1in which a damper mechanism4according to the present invention has been installed will be described through reference toFIG. 1or2.FIG. 1is a simplified vertical cross section of the clutch disk assembly1, andFIG. 2is a simplified elevational view of the clutch disk assembly1. The O-O line inFIG. 1is the rotational axis of the clutch disk assembly1. Also, an engine and a flywheel (not shown) are disposed on the left side inFIG. 1, and a transmission (not shown) is disposed on the right side inFIG. 1. Further, the R1 side inFIG. 2is the rotational direction drive side (positive side) of the clutch disk assembly1, while the R2 side is the opposite side (negative side).

The clutch disk assembly1is a mechanism used in a clutch device that constitutes part of a power transmission system in a vehicle, and has a clutch function and a damper function. The clutch function is to transmit and to shut off torque by using a pressure plate (not shown) to press the clutch disk assembly1against, or release it from, the flywheel (not shown). The damper function is to absorb and to damp torsional vibration inputted from the flywheel side by means of coil springs or the like.

As shown inFIGS. 1 and 2, the clutch disk assembly1mainly has a clutch disk23to which torque is inputted from the flywheel by frictional engagement, and a damper mechanism4that absorbs and damps torsional vibration inputted from the clutch disk23.

The clutch disk23is the portion that is pressed against the fly wheel (not shown), and mainly has a pair of annular friction facings25and a cushioning plate24to which the friction facings25are fixed. The cushioning plate24has an annular component24a, eight cushioning components24bprovided on the outer peripheral side of the annular component24aand aligned in the rotational direction, and four fixed components24cextending inward in the radial direction from the annular component24a. The friction facings25are fixed by rivets26to both sides of the cushioning components24b. The fixed components24care fixed to the outer peripheral part of the damper mechanism4.

2. Configuration of Damper Mechanism

2.1 Summary of Damper Mechanism

The damper mechanism4has the torsional characteristics shown inFIG. 11in order to damp and to absorb effectively torsional vibration transmitted from the engine. More specifically, the torsional characteristics of the damper mechanism4have four-stage characteristics on the positive side, and three-stage characteristics on the negative side. On the positive side of the torsional characteristics, the first and second stage regions (torsion angle of 0 to θ1p) are regions of low torsional stiffness and low hysteresis torque, and the third and fourth stage regions (torsion angle of θ1pto θ1p+θ3p) are regions of high torsional stiffness and high hysteresis torque. On the negative side of the torsional characteristics, the first stage region (torsion angle of 0 to θ1n) is a region of low torsional stiffness and low hysteresis torque, and the second and third stage regions (torsion angle of θ1nto θ1n+θ3n) are regions of high torsional stiffness and high hysteresis torque. Due to these torsional characteristics, the damper mechanism4can effectively damp and absorb torsional vibration, such as idling noises, tip-in and tip-out (low-frequency vibrations), etc.

Also, with this damper mechanism4, a rotational direction gap (gap angle of θ6) for preventing the generation of high hysteresis torque only on the negative side of the torsional characteristics is provided in order to damp and to absorb minute torsional vibrations. The reason for not providing a rotational direction gap on the positive side of the torsional characteristics is to prevent the generation of a resonance peak on the positive side of the torsional characteristics.

2.2: Configuration of Damper Mechanism

The damper mechanism4has the following configuration in order to obtain the above-mentioned torsional characteristics. The various members constituting the damper mechanism4will how be described in detail with reference toFIGS. 1 to 12.FIG. 3is a simplified elevational view of the damper mechanism4,FIG. 4is an elevational view of a hub flange6,FIG. 5is an elevational view of an input rotary member2,FIGS. 6 and 7are partial cross sections of the damper mechanism4,FIGS. 8 and 9are partial cross sections of the damper mechanism4, andFIG. 10is a simplified oblique view of a first bushing90.FIG. 6is a simplified cross section taken along line A inFIG. 2, andFIG. 7is a simplified cross section taken along line B inFIG. 2.FIG. 8is a simplified elevational view of a cross section along line C inFIG. 7, andFIG. 9is a simplified elevational view of a cross section along D inFIG. 7.FIG. 12is a mechanical circuit diagram of the damper mechanism4. The mechanical circuit diagram shown inFIG. 12schematically illustrates the relationship of the various members of the damper mechanism in the rotational direction. Therefore, members that rotate integrally are treated as the same member. The left-right direction inFIG. 12corresponds to the rotational direction.

As shown inFIG. 1, the damper mechanism4mainly has the input rotary member2serving as the first rotary member to which the clutch disk23is fixed, the hub flange6serving as the second rotary member and disposed rotatably with respect to the input rotary member2, a spline hub3serving as the third rotary member and disposed rotatably with respect to the hub flange6, first small coil springs7aand second small coil springs7bthat elastically link the hub flange6and the spline hub3in the rotational direction, and large coil springs8serving as the elastic members that elastically link the input rotary member2and the hub flange6in the rotational direction. The spline hub3is spline-engaged with the end of an input shaft of a transmission (not shown).

As shown inFIG. 12, the first small coil springs7aand the second small coil springs7bare disposed in parallel, and the large coil springs8are disposed in parallel. The first small coil springs7aand second small coil springs7band the large coil springs8are disposed in series via the hub flange6and its surrounding members. The first small coil springs7aand second small coil springs7bare less stiff than the large coil springs8.

2.2: Input Rotary Member

As shown inFIG. 1andFIGS. 5 to 7, the input rotary member2include a clutch plate21and a retaining plate22. The clutch plate21and the retaining plate22are disk-shaped or annular members made of sheet metal, and are disposed spaced apart a specific distance in the axial direction. The clutch plate21is disposed on the engine side, while the retaining plate22is disposed on the transmission side. The clutch plate21and the retaining plate22are fixed to each other by linking components31(discussed below). Therefore, the clutch plate21and the retaining plate22are able to rotate integrally in a state in which the specific spacing is maintained in the axial direction. Also, the fixed components24cof the clutch disk23are fixed by rivets27to the outer peripheral part of the clutch plate21.

The function of the clutch plate21and the retaining plate22is to support the large coil springs8. More specifically, the clutch plate21and the retaining plate22include a pair of annular first main body components28, four support components35disposed aligned in the rotational direction around the outer peripheral part of the first main body components28, and four linking components31disposed between the support components35in the rotational direction.

The support components35have flared components35aand35bon the inner peripheral side and outer peripheral side. The flared components35aand35brestrict movement of the large coil springs8in the axial direction and the radial direction. The length of the support components35in the rotational direction substantially coincides with the free length of the large coil springs8. Contact faces36that come into contact, or nearly come into contact, with the end of the large coil springs8are formed at the ends of the support components35in the circumferential direction.

The linking components31are disposed on the outer peripheral side of the pair of first main body components28, and link the pair of first main body components28. More specifically, each of the linking components31has a contact component32, which extends in the axial direction from the outer peripheral edge of one of the first main body components28(in this embodiment, the first main body component28of the retaining plate22) to the other first main body component28(in this embodiment, the first main body component28of the clutch plate21), and a fixed component33that extends inward in the radial direction from the end of the contact component32(seeFIG. 7). The fixed components33are fixed to the fixed components24cof the clutch disk23and by the rivets27to the first main body components28of the clutch plate21.

The spline hub3is disposed in the center holes37and38of the clutch plate21and the retaining plate22. The spline hub3has a cylindrical boss52extending in the axial direction, and a flange54extending outward in the radial direction from the boss52. A spline hole53that engages with the input shaft of the transmission (not shown) is formed in the inner peripheral part of the boss52.

As shown inFIG. 12, the hub flange6is elastically linked in the rotational direction with respect to the input rotary member2. More specifically, as shown inFIGS. 1 to 7, the hub flange6is disposed relatively rotatably in the axial direction between the clutch plate21and the retaining plate22, and is elastically linked in the rotational direction to the clutch plate21and the retaining plate22by the large coil springs8. The hub flange6has an annular second main body component29, a pair of first windows41and a pair of second windows42formed at the outer peripheral part of the second main body component29, and four cut-outs43formed at the outer peripheral part of the second main body component29. The pair of first windows41and the pair of second windows42are disposed at locations corresponding to the four support components35. The first windows41are disposed opposite one another in the radial direction, and the second windows42are disposed opposite one another in the radial direction.

As shown inFIGS. 3 and 12, the large coil springs8are housed in the first windows41and the second windows42. The length of the first windows41in the rotational direction is set longer than the free length of the large coil springs8(the length of the support components35in the rotational direction), and the length of the second windows42in the rotational direction is set to be substantially the same as the free length of the large coil springs8(the length of the support components35). First contact faces44and second contact faces47that come into contact, or nearly come into contact, with the end faces of the large coil springs8are formed at both ends of the first windows41and the second windows42in the circumferential direction. In a neutral state, the gap angle θ2pis maintained between the first contact faces44and the ends of the large coil springs8on the R1 side. The gap angle θ2nis maintained between the first contact faces44and the ends of the large coil springs8on the R2 side. These configurations afford regions in which two large coil springs8are compressed in parallel (the third stage region on the positive side and the second stage region on the negative side) and regions in which four large coil springs8are compressed in parallel (the fourth stage region on the positive side and the third stage region on the negative side) (FIG. 11). Also, in a neutral state in which no torque is inputted, the relative positions of the input rotary member2and the hub flange6in the rotational direction are determined by the two large coil springs8held in the second windows42.

As shown inFIG. 12, the spline hub3is elastically linked to the hub flange6in the rotational direction. More specifically, as shown inFIGS. 1 to 7, a plurality of outer peripheral teeth55is formed around the outer peripheral part of a flange54of the spline hub3. A plurality of inner peripheral teeth59are formed as the first inner peripheral teeth around the inner peripheral part of the hub flange6. The outer peripheral teeth55and inner peripheral teeth59mesh with a specific gap in between. In a neutral state in which no torque is inputted, a gap is formed in the rotational direction between the outer peripheral teeth55and the inner peripheral teeth59. The torsional angle corresponding to the gap formed on the R1 side of the inner peripheral teeth59is the gap angle θ1p. The torsional angle corresponding to the gap formed on the R2 side of the inner peripheral teeth59is the gap angle θ1n.

As shown inFIGS. 1 and 6, each of the large coil springs8includes a pair of coil springs of different diameters disposed concentrically. The large coil springs8are longer and larger in diameter than the first small springs7aand second small coil springs7b. The spring constant of the large coil springs8is set to a value that is much higher than the spring constant of the first small coil springs7aand second small coil springs7b. Specifically, the large coil springs8are much stiffer than the first small coil springs7aand second small coil springs7b. Accordingly, when torque is inputted to the input rotary member2, the first small coil springs7aand second small coil springs7bbegin to compress between the hub flange6and the spline hub3, and when the hub flange6and the spline hub3rotate integrally, the large coil springs8begin to compress between the input rotary member2and the hub flange6.

The damper mechanism4is provided with a first stopper9and a second stopper10for directly transmitting torque that has been inputted to the input rotary member2.

As shown inFIG. 9, the first stopper9is a mechanism for limiting relative movement between the hub flange6and the spline hub3to a specific range, and includes the outer peripheral teeth55of the spline hub3and the inner peripheral teeth59of the hub flange6. The first stopper9permits relative rotation between the hub flange6and the spline hub3within a range of the gap angles θ1pand θ1n. As shown inFIG. 11, the range of low torsional stiffness is determined by the gap angles θ1pand θ1n.

As shown inFIG. 3, the second stopper10is a mechanism for limiting relative movement between the hub flange6and the spline hub3to a specific range, and includes the linking components31of the input rotary member2and the first protrusions49and second protrusions57of the hub flange6.

More specifically, a pair of first protrusions49and a pair of second protrusions57extending outward in the radial direction are formed around the outer peripheral edge of the second main body component29. The first protrusions49and the second protrusions57are disposed on the outer peripheral side of the first windows41and the second windows42, and stopper faces50and51are formed at the ends in the rotational direction. The stopper faces50and51are able to come into contact with stopper faces39of the linking components31.

In the neutral state shown inFIG. 3, a gap is ensured in the rotational direction between the linking components31and the first protrusions49and second protrusions57. The torsional angles corresponding to this gap (first angles) are the gap angles θ3pand θ3n. The gap formed on the R1 side of the linking components31corresponds to the gap angle θ3p, while the gap formed on the R2 side of the linking components31corresponds to the gap angle θ3n. Consequently, the second stopper10permits relative rotation of the input rotary member2and the spline hub3within the range of the gap angles θ3pand θ3n. As shown inFIG. 11, the range of low torsional stiffness is determined by the gap angles θ3pand θ3n.

2.2.6: Friction Generating Mechanism

The most salient feature of the damper mechanism4lies in the configuration of the friction generating mechanism5. The friction generating mechanism5for utilizing frictional resistance to generate hysteresis torque is provided to the damper mechanism4in order to absorb and damp torsional vibration more effectively. More specifically, as shown inFIGS. 6 and 7, the friction generating mechanism5includes a first friction washer79, a second friction washer72, a third friction washer84, a fourth friction washer85, a first bushing90, and a second bushing89. The second friction washer72and the first bushing90constitute the above-mentioned friction member.

The hysteresis torque shown inFIG. 11is attained by the friction generating mechanism5. More specifically, the first low hysteresis torque Th1shown inFIG. 11is generated by the first friction washer79and the fourth friction washer85. The high hysteresis torque Th2is generated by the first friction washer79, the second bushing89, the second friction washer72, and the fourth friction washer85. The second low hysteresis torque Th3is generated by the third friction washer84and the first bushing90.

The first low hysteresis torque Th1is generated in the entire region of torsional characteristics. The high hysteresis torque Th2is generated in the third and fourth stage regions on the positive side of the torsional characteristics, and in the second and third stage regions on the negative side of the torsional characteristics. The high hysteresis torque Th2includes the first low hysteresis torque Th1. The second low hysteresis torque Th3is generated only when the generation of high hysteresis torque is prevented by a rotational direction gap. The second low hysteresis torque Th3includes the first low hysteresis torque Th1.

To attain these hysteresis torque characteristics, the various members of the friction generating mechanism5have the following configuration. More specifically, as shown inFIGS. 6 and 7, the first friction washer79and the second friction washer72are disposed between the hub flange6and the retaining plate22in the axial direction. The third friction washer84, the fourth friction washer85, and the second bushing89are disposed between the hub flange6and the clutch plate21in the axial direction. The second friction washer72and the fourth friction washer85are linked by the first bushing90so as to be capable of integral rotation. The fourth friction washer85and the second bushing89are elastically linked in the rotational direction by the first small coil springs7aand second small coil springs7b. The second bushing89is linked to the spline hub3so as to be capable of integral rotation. Accordingly, the second friction washer72, the first bushing90, and the fourth friction washer85are elastically linked in the rotational direction via the second bushing89, the first small coil springs7a, and the second small coil springs7b.

The first friction washer79is disposed between the flange54of the spline hub3and the inner peripheral part of the retaining plate22in the axial direction, and is disposed on the outer peripheral side of a boss52. The first friction washer79is made of plastic, for example. A first cone spring80is disposed between the first friction washer79and the flange54. The first cone spring80is compressed in the axial direction between the first friction washer79and the retaining plate22. Accordingly, the first friction washer79is pressed against the retaining plate22by the first cone spring80.

The second friction washer72is disposed between the inner peripheral part of the hub flange6and the inner peripheral part of the retaining plate22, and is disposed on the outer peripheral side of the first friction washer79. More specifically, the second friction washer72primarily includes an annular washer main body72a, four engagement components72bthat extend in the axial direction from the outer peripheral edge of the washer main body72a, and a friction member74that is fixed to the washer main body72a. A second cone spring81is disposed in a state of being compressed in the axial direction between the second friction washer72and the first bushing90. Accordingly, the friction face of the friction member74of the second friction washer72is pressed against the retaining plate22by the second cone spring81. The second friction washer72is engaged in the rotational direction with the first bushing90by the engagement components72b. Consequently, the second friction washer72and the first bushing90are able to rotate integrally.

As shown inFIGS. 6 and 10, the first bushing90is disposed between the second friction washer72and the hub flange6(more specifically, between the second cone spring81and die hub flange6). The first bushing90mainly comprises a first annular component91, a second annular component92, and four linking components93that elastically link the first annular component91and the second annular component92in the rotational direction. The first bushing90is an integrally molded plastic member, for example.

The first annular component91and the second annular component92are annular plate-shaped members, and the first annular component91is disposed on the outer peripheral side of the second annular component92. As shown inFIGS. 6 and 7, the first annular component91is biased to the engine side by the second cone spring81.

The first annular component91has an annular main body component91a, four extensions91bthat extend inward in the radial direction from the main body component91a, protrusions94that extend in the axial direction from the extensions91b, and concave components91cformed on the outer peripheral side of the main body component91a. Linking components93are disposed between adjacent extensions91b. The concave components91care disposed on the outer peripheral side of the linking components93. The concave components91care recessed in the radial direction. The four engagement components72bof the washer main body72aare inserted in the axial direction in the concave components91c. Consequently, the first annular component91and the second friction washer72are capable of relative rotation and are capable of relative movement in the axial direction.

The second annular component92has an annular main body92aand a plurality of inner peripheral teeth95serving as the second inner peripheral teeth and extending inward in the radial direction from the main body92a. The inner peripheral teeth95mesh with the outer peripheral teeth55of the spline hub3(discussed below), with a gap in between. The gap on the R2 side of the inner peripheral teeth95corresponds to the gap angle θ4n. The second annular component92also has a plurality of sliding components92bthat come into contact with the hub flange6. The sliding components92bextend in the axial direction, and come into contact with the face of the hub flange6on the transmission side. Accordingly, the first annular component91and the main body92ado not come into contact with the hub flange6.

The linking components93have three deformation components96that extend from the inner peripheral part of the first annular component91(more specifically, the inner peripheral part of the main body component91a) to the outer peripheral part of the second annular component92. The deformation components96are bent in a wave shape (S shape). One end of the deformation components96is integrally linked to the inner peripheral part of the main body component91aand the portion of the extensions91bon the R1 side, and the other end of the deformation components96is integrally linked to the outer peripheral part of the main body92a. More specifically, one end of the deformation components96is a portion extending inward in the radial direction from the inner peripheral part of the first annular component91, and the other end of the deformation components96is a portion extending outward in the radial direction from the outer peripheral part of the second annular component92. The two ends of the deformation components96are linked by two semicircular parts. Thus, the deformation components96are capable of overall elastic deformation in the rotational direction.

The configuration of the linking components93will be described from another standpoint. The first annular component91, the second annular component92, and the linking components93can be considered to be formed by forming a plurality of slits98by punching, etc., in a single annular plate-shaped member. The slits98are bent in a rough wave shape (S shape), and the slits98are put together in a complementary fashion. The width of the slits98is determined on the basis of the relative torsional angle needed for the first annular component91and the first annular component91. More specifically, the width is determined so that the first annular component91and the second annular component92will be capable of relative rotation of at least an angle θ1pto θ4p.

With the above configuration, the first annular component91and the second annular component92are elastically linked in the rotational direction by the linking components93. Accordingly, when the first annular component91and the second annular component92rotate relatively, the deformation components96of the linking components93undergo elastic deformation. As a result, a force in the rotational direction that attempts to put the first annular component91and the second annular component92in a neutral state is generated between the first annular component91and the second annular component92.

The protrusions94are disposed near the center of the extensions91bin the circumferential direction. The protrusions94extend in the rotational direction from the extensions91bto the clutch plate21side. A cross section of the protrusions94is substantially fan shaped. More specifically, the inner and outer faces in the radial direction are arc-shaped, while the contact faces94aon the R1 and R2 sides in the rotational direction are flat. The contact faces94aare formed in the radial direction, and are substantially perpendicular to the rotational direction. The protrusions94are inserted into holes99formed in the hub flange6. A gap is maintained between the contact faces94aof the protrusions94and the contact faces99aof the holes99. The torsional angle (second angle) corresponding to this gap is the gap angle θ6. Accordingly, the first annular component91is capable of relative rotation within a range of the gap angle θ6in the rotational direction with respect to the hub flange6. This gap angle θ6corresponds to the above-mentioned rotational direction gap (the gap for preventing the generation of high hysteresis torque).

The inner peripheral teeth95mesh with the outer peripheral teeth55via a gap. In a neutral state, when the protrusions94are in contact with the holes99on the R1 side in the rotational direction, a gap is maintained between the inner peripheral teeth95and the outer peripheral teeth55in the rotational direction. The torsional angle corresponding to the gap on the R1 side of the inner peripheral teeth95is the gap angle θ4p. The torsional angle corresponding to the gap on the R2 side of the inner peripheral teeth95is the gap angle θ4n. The gap angle θ4nis substantially the same size as the gap angle θ1n, but the gap angle θ4pis smaller than the gap angle θ1n. Accordingly, when the hub flange6and the first bushing90rotate relatively to the R1 side with respect to the spline hub3, first the outer peripheral teeth55hit the inner peripheral teeth95, and when relative rotation proceeds further, the outer peripheral teeth55hit the inner peripheral teeth59while in contact with the inner peripheral teeth95. Since the second annular component92is pressed by the outer peripheral teeth55at this point, the second annular component92rotate relatively to the R2 side with respect to the hub flange6. Meanwhile, the protrusions94restrict the relative rotation of the first annular component91to the R2 side with respect to the hub flange6. Accordingly, in a state in which the outer peripheral teeth55are in contact with the inner peripheral teeth95and the inner peripheral teeth59, the linking components93are elastically deformed between the first annular component91and the second annular component92. The elastic force of the linking components93presses the protrusions94of the first annular component91against the contact faces99aon the R2 side of the holes99. In this state, the first annular component91and the hub flange6function as an integral member.

The fourth friction washer85is an annular member disposed between the hub flange6and the clutch plate21. More specifically, as shown inFIGS. 6 and 7, the fourth friction washer85mainly has a main body85a, an outer peripheral part85b, and a friction member66fixed to the main body85a. Four concave components85care formed in the main body85a. The concave components85care recessed in the axial direction, and their shape is substantially the same as a cross section of the protrusions94. The protrusions94of the first bushing90are fitted into the concave components85cin a state of having substantially no gap in the rotational direction or the radial direction. Accordingly, the first bushing90and the fourth friction washer85rotate integrally. Also, the end faces94bof the protrusions94come into contact in the rotational direction with the bottom faces of the concave components85c(the faces oriented in the axial direction). Accordingly, the fourth friction washer85is pressed against the clutch plate21by the second cone spring81via the first bushing90.

The annular outer peripheral part85bthat sticks out on the hub flange6side is formed on the outer peripheral side of the main body85a. The third friction washer84is disposed between the main body85aand the hub flange6. A third cone spring82is disposed between the third friction washer84and the outer peripheral part85bin a state of being compressed in the axial direction. Accordingly, the third friction washer84is pressed against the hub flange6by the third cone spring82.

The second bushing89is an annular member disposed between the fourth friction washer85and the hub flange6. More specifically, the second bushing89includes a sliding component89aand an engagement component89bdisposed on the outer peripheral side of the sliding component. The sliding component89ais an annular member that is disposed between the flange54and the inner peripheral edge of the clutch plate21, and is capable of sliding with the inner peripheral part of the clutch plate21. A plurality of inner peripheral teeth89fextending inward in the radial direction is formed on the inner peripheral part of the engagement component89b. The inner peripheral teeth89fmesh with the outer peripheral teeth55in a state in which there is substantially no gap. Consequently, the spline hub3and the second bushing89rotate integrally.

Four first cut-outs89c, two second cut-outs89d, and two third cut-outs89eare formed in the outer peripheral part of the engagement component89b. The first cut-outs89care disposed at positions corresponding to the protrusions94. The length of the first cut-outs89cin the rotational direction is greater than the length of the protrusions94in the rotational direction. In a neutral state, a gap is formed between the protrusions94and the first cut-outs89c. The torsional angle corresponding to the R1 side of the protrusions94is the gap angle θ7p. The torsional angle corresponding to the R2 side of the protrusions94is the gap angle θ7n. The second cut-outs89dare disposed at positions corresponding to the radial direction, flanking the rotational axis O. The third cut-outs89eare disposed at positions corresponding to the radial direction, flanking the rotational axis O. The first cut-outs89care disposed between the second cut-outs89dand the third cut-outs89ein the radial direction.

Two first holders85dand two second holders85eare formed in the fourth friction washer85. The first holders85dand the second holders85eare recessed in the axial direction. The positions of the first holders85dand the second holders85ein the radial direction substantially coincide with the concave components85c. The first holders85dare formed at positions corresponding to the second cut-outs89din the second bushing89, and the second holders85eare formed at positions corresponding to the third cut-outs89e.

The above-mentioned first small coil springs7aare held in the first holders85dand the second cut-outs89d. The above-mentioned second small coil springs7bare held in the second holders85eand the third cut-outs89e. The length of the first holders85dand the second cut-outs89din the rotational direction is substantially the same as the natural length of the first small coil springs7a. The length of the third cut-outs89ein the rotational direction may be greater than the length of the second small coil springs7b. A gap is maintained between the ends of the second small coil springs7band the edges of the third cut-outs89ein the rotational direction. The torsional angle corresponding to the gap on the R1 side of the second small coil springs7bis the gap angle θ5p, and the torsional angle corresponding to the gap on the R2 side of the second small coil springs7bis the gap angle θ5n.

The above configuration affords regions in which the two first small coil springs7aare compressed in parallel (the first stage region on the positive side, and the first stage region on the negative side), and a region in which the two first small coil springs7aand the two small coil springs7bare compressed in parallel (the second stage region on the positive side) (FIG. 11). In a neutral state in which no torque is inputted, the relative positions of the fourth friction washer85and the second bushing89in the rotational direction are determined by the second small coil springs7bheld in the first holders85dand the second cut-outs89d.

The biasing force generated by the third cone spring82is less than the biasing force generated by the first cone spring80and the third cone spring82. Also, the coefficient of friction between the first friction washer79and the retaining plate22is lower than the coefficient of friction between the friction member74and the retaining plate22. Accordingly, the hysteresis torque generated by the first friction washer79is much lower than the hysteresis torque generated by the second friction washer72. Also, the coefficient of friction between the third friction washer84and the hub flange6, and the coefficient of friction between the second bushing89and the clutch plate21are both lower than the coefficient of friction between the fourth friction washer85and the clutch plate21. Accordingly, the hysteresis torque generated by the third friction washer84and the second bushing89is much lower than the coefficient of friction generated by the fourth friction washer85.

As discussed above, a large friction generating mechanism14is constituted by the second friction washer72and the fourth friction washer85, a first small friction generating mechanism15is constituted by the first friction washer79and the second bushing89, and a second small friction generating mechanism16is constituted by the first bushing90and the third friction washer84. When the input rotary member2, the hub flange6, and the spline hub3rotate relatively, the large friction generating mechanism14, the first small friction generating mechanism15, and the second small friction generating mechanism16generate hysteresis torque, and torsional vibration can be more effectively damped and absorbed by the damper mechanism4.

The structure described above can also be such that a first damper, having the first small coil springs7a, the second small coil springs7b, and the first stopper9, and a second damper, having the large coil springs8and the second stopper10, are disposed in series.

Next, the torsional characteristics and the operation of the damper mechanism of the clutch disk assembly1will be described through reference toFIGS. 12 to 19.FIG. 12is a mechanical circuit diagram of neutral state (a state in which no torque is inputted).FIGS. 13 to 16are mechanical circuit diagrams showing operation on the positive side of the torsional characteristics.FIGS. 17 to 19are mechanical circuit diagrams showing operation on the negative side of the torsional characteristics.

4.1: Positive Side of Torsional Characteristics

4.1.1: First and Second Stage Regions

On the positive side of the torsional characteristics, the input rotary member2is twisted from the neutral state inFIG. 12to the R1 side (drive side) with respect to the spline hub3. At this point the stiffness of the first small coil springs7ais much lower than the stiffness of the large coil springs8, so the large coil springs8are hardly compressed at all, and the input rotary member2and the hub flange6rotate integrally. At this point the protrusions94of the first bushing90are pressed to the R1 side by the edges of the holes99in the hub flange6. Accordingly, the first bushing90, the second friction washer72, and the fourth friction washer85also rotate integrally along with the input rotary member2and the hub flange6. As a result, the first small coil springs7aare compressed between the hub flange6and the spline hub3(more specifically, between the fourth friction washer85and the second bushing89).

When the input rotary member2rotates relatively to the R1 side with respect to the spline hub3by the torsional angle θ4p, the inner peripheral teeth95of the first bushing90come into contact with the outer peripheral teeth55of the spline hub3(FIG. 13). As the relative rotation of the input rotary member2with respect to the spline hub3progresses, the inner peripheral teeth95are pushed by the outer peripheral teeth55, and the linking components93undergo elastic deformation in the rotational direction. Also, in addition to the first small coil springs7a, compression of the second small coil springs7bcommences between the fourth friction washer85and the second bushing89.

When the torsional angle of the input rotary member2with respect to the spline hub3reaches the angle θ1p, the outer peripheral teeth55hit the inner peripheral teeth59and the first stopper9comes into play. As a result, the relative rotation of the hub flange6and the spline hub3stops. Accordingly, the compression of the first small coil springs7aand the second small coil springs7balso stops (FIG. 14).

Also, when the input rotary member2rotates with respect to the spline hub3, the first low hysteresis torque Th1is generated in the first small friction generating mechanism15.

The result of the above operation is that the torsional characteristics of the first and second stage regions of low hysteresis torque and low-torsional stiffness are realized (FIG.11).

When the outer peripheral teeth55hit the inner peripheral teeth59, the elastic deformation of the linking components93stops (FIG. 14). In this state, a biasing force in the rotational direction is exerted by the linking components93between the first annular component91and the second annular component92. Accordingly, the protrusions94are pressed to the R2 side of the holes99, and the inner peripheral teeth95are pressed to the R1 side of the outer peripheral teeth55. Consequently, the first bushing90can function as an integral member with the hub flange6and the spline hub3.

4.1.2: Third and Fourth Stage Regions

When the input rotary member2rotates further to the R1 side from the state inFIG. 14, the input rotary member2rotates relatively with respect to the hub flange6, and compression commences of the two large coil springs8held in the second windows42between the input rotary member2and the hub flange6. The two large coil springs8are compressed in parallel until the torsional angle is an angle of θ1p+θ2p.

As the relative rotation of the input rotary member2with respect to the spline hub3progresses, the four large coil springs8begin to be compressed (FIG. 15). When the torsional angle reaches an angle of θ1p+θ3p, the second stopper10comes into play, and the relative rotation of the input rotary member2and the spline hub3stops.

Also, when the input rotary member2and the hub flange6rotate relatively, high hysteresis torque is generated not only by the first small friction generating mechanism15, but also by the large friction generating mechanism14(the second friction washer72and the fourth friction washer85).

The result of the above operation is that the torsional characteristics of the third and fourth stage regions of high hysteresis torque and high torsional stiffness are realized (FIG. 11).

4.2: Negative Side of Torsional Characteristics

4.2.1: First Stage Region

On the negative side of the torsional characteristics, the input rotary member2is twisted from the neutral state inFIG. 12to the R2 side (the non-drive side) with respect to the spline hub3. At this point the stiffness of the first small coil springs7ais much lower than the stiffness of the large coil springs8, so the large coil springs8are hardly compressed at all, and the input rotary member2and the hub flange6rotate integrally. The coefficient of friction between the second friction washer72and the retaining plate22, and the coefficient of friction between the fourth friction washer85and the clutch plate21are both large. As a result, the hysteresis torque generated by the large friction generating mechanism14is much higher than the torque required to compress the first small coil springs7a. Therefore, the fourth friction washer85rotates relatively with the input rotary member2, and the first small coil springs7aare compressed between the fourth friction washer85and the second bushing89. Once the torsional angle reaches the angle θ1n, the inner peripheral teeth59hit the outer peripheral teeth55, and the first stopper9comes into play (FIG. 17). In this state, the gap angle θ5n−θ1n(>0) is maintained between the second small coil springs7band the third cut-outs89e. Accordingly, on the negative side the second small coil springs7bare not compressed.

Also, the first low hysteresis torque Th1is generated by the first small friction generating mechanism15until the torsional angle reaches the angle θ1n.

The result of the above operation is that the torsional characteristics of the first stage region of low hysteresis torque and low torsional stiffness are realized (FIG. 11).

4.2.2: Second and Third Stage Regions

When the input rotary member2rotates further to the R2 side from the state inFIG. 17, the input rotary member2rotates relatively with respect to the hub flange6, and compression of the two large coil springs8held in the second windows42between the input rotary member2and the hub flange6commences. The two large coil springs8are compressed in parallel until the torsional angle is an angle of θ1n+θ2n.

As the relative rotation of the input rotary member2with respect to the spline hub3progresses, the four large coil springs8begin to be compressed (FIG. 19). When the torsional angle reaches an angle of θ1n+θ3n, the second stopper10comes into play, and the relative rotation of the input rotary member2and the spline hub3stops.

Also, when the input rotary member2and the hub flange6rotate relatively, high hysteresis torque is generated not only by the first small friction generating mechanism15, but also by the large friction generating mechanism14(the second friction washer72and the fourth friction washer85).

The result of the above operation is that the torsional characteristics of the second and third stage regions of high hysteresis torque and high torsional stiffness are realized (FIG. 11).

4.3: Operation for Minute Torsional Vibrations

4.3.1: Third and Fourth Stage Regions on Positive Side of Torsional Characteristics

During vehicle acceleration (positive side of torsional characteristics), the damper mechanism4transmits torque, in a state in which the first stopper9and the second stopper10are operating (the state inFIG. 16, in which the torsional angle is an angle of θ1p+θ3p). In this state, when minute torsional vibrations originating in combustion fluctuations of the engine are inputted to the input rotary member2, the stiff large coil springs8repeatedly expand and contract between the input rotary member2and the hub flange6.

Meanwhile, in the state inFIG. 16, as mentioned above, the linking components93of the first bushing90are compressed in the rotational direction, and this biasing force causes the first bushing90to function as an integral member with respect to the hub flange6and the spline hub3. Accordingly, the first bushing90, the second friction washer72, and the fourth friction washer85repeatedly undergo relative rotation within a minute torsional angle range with the input rotary member2. As a result, as shown inFIG. 11, high hysteresis torque Th2is generated by the large friction generating mechanism14and the small friction generating mechanism15with respect to the minute torsional vibrations.

Thus, even if minute torsional vibrations should be inputted during acceleration, high hysteresis torque is always generated. Specifically, with this damper mechanism4, no rotational direction gap is maintained that would prevent the generation of high hysteresis torque on the positive side of the torsional characteristics. Consequently, the generation of a resonance peak during acceleration is suppressed.

4.3.2: Second and Third Stage Regions on Negative Side of Torsional Characteristics

During vehicle deceleration (negative side of torsional characteristics), the damper mechanism4transmits torque in a state in which the first stopper9and the second stopper10are operating (the state inFIG. 19, in which the torsional angle is an angle of θ1n+θ3n). In this state, when minute torsional vibrations are inputted to the input rotary member2, the large coil springs8repeatedly expand and contract between the input rotary member2and the hub flange6.

Meanwhile, in the state inFIG. 19, the linking components93of the first bushing90are not compressed in the rotational direction. Accordingly, unlike during acceleration, the first bushing90, the second friction washer72, and the fourth friction washer85are capable of relative rotation with respect to the hub flange6and the spline hub3. When minute torsional vibrations are inputted to the input rotary member2in this state, no slip occurs in the large friction generating mechanism14that generates high hysteresis torque. Specifically, the input rotary member2, the first bushing90, the second friction washer72, and the fourth friction washer85function as an integral member.

As a result, as shown inFIG. 11, within the range of the gap angle θ6formed between the holes99and the protrusions94, the first bushing90, the second friction washer72, and the fourth friction washer85rotate relatively, and the second low hysteresis torque Th3is generated by the second small friction generating mechanism16(the first bushing90and the third friction washer84). At this point the high hysteresis torque Th2is hot generated within the range of the gap angle θ6.

Thus, even if minute torsional vibrations are inputted during acceleration, the generation of high hysteresis torque is suppressed within the range of the gap angle θ6.

5. Operation and Effect

With this damper mechanism4, the elastic force of the linking components93of the first bushing90is utilized to generate the high hysteresis torque Th2in all torsional vibration on one side (the positive side) of the torsional characteristics, while the generation of the high hysteresis torque Th2can be prevented within the range of a specific torsional angle (the gap angle θ6) on the other side (the negative side) of the torsional characteristics. Consequently, with this damper mechanism4, the structure can be simplified and manufacturing cost can be reduced.

Also, manufacturing cost can be further reduced by integrally forming the various components of the first bushing90. The various deformation components96of the linking components93are particularly easy to form because they can be formed by punching out, etc., the slits98from a disk-shaped member.

Furthermore, with this damper mechanism4, the first small coil springs7aand the second small coil springs7bused to achieve low torsional stiffness are disposed on the outer peripheral side of the spline hub3and between the hub flange6and the clutch plate21in the rotational direction. Accordingly, there is more latitude in the design of the first small coil springs7aand the second small coil springs7bthan with a conventional structure (a structure in which coil springs are provided between a hub flange and a spline hub), and the vibration damping performance is improved.

6. Other Embodiments

The specific constitution of the present invention is not limited to that in the embodiment given above, and various modifications and changes are possible without departing from the scope of the invention.

With the above embodiment, the clutch disk assembly1in which the damper mechanism4was installed was described as an example, but the present invention is not limited to this. For instance, this damper mechanism can also be applied to a two-mass flywheel, a lock-up device for a fluid torque transmission device, or another such power transmission device.

Also, the shape of the first bushing90is not limited to what was described above. For instance, the first bushing190shown inFIG. 20can also be used. With this first bushing190, deformation components196of linking components193extend in the radial direction, and are not curved like the above-mentioned deformation components96. Also, slits198are elliptical in shape, for example. Here again, a first annular component191and a second annular component192can be elastically linked in the rotational direction, and the same effect as above can be obtained.

INDUSTRIAL APPLICABILITY

With the damper mechanism pertaining to the present invention, a structure is achieved in which high hysteresis torque is not generated with respect to torsional vibration, and manufacturing cost can be reduced.