Patent Application
20080029360
This application claims the benefit of priority under 35 USC 119 of Japanese patent application nos. 2006-212621, filed on Aug. 3, 2006, which application is hereby incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to an automatic clutch mechanism, and more specifically to an automatic clutch mechanism suitable for use in straddle-type vehicles such as a motorcycle or ATV.
2. Description of Related Art
With a view to achieving improved operability for the rider, a straddle-type vehicle equipped with an automatic clutch mechanism has been proposed for effecting clutch disengagement/engagement and gear shift simultaneously solely by operating a shift pedal with a foot (for example, see JP-A-2005-42910). In JP-A-2005-42910, a coil spring (elastic member) urges a pressure plate to bring a friction plate and a clutch plate into press contact with each other. The coil spring is placed under compression so as to be capable of urging the pressure plate with a required elastic reaction force at all times. A release mechanism actuated by operation of a pedal displaces the pressure plate against the elastic reaction force of the coil spring to thereby disengage the clutch. A mechanism for shifting gears is actuated when the clutch is disengaged, thereby shifting gears.
In the automatic clutch mechanism as described above, it is desired to make the operation reaction force encountered during pedal operation small. Further, at the time of gear shifting, the change in the reaction force exerted on the pedal is small in comparison with the reaction force exerted on the pedal. Therefore, the automatic clutch mechanism has a problem in that the feel of gear shifting is not effectively transmitted to the rider through the pedal.
According to an embodiment of the present invention, an automatic clutch mechanism is provided that shifts gears while disengaging a clutch in conjunction with one pedal operation. A transmission shifts gears in conjunction with pedal operation. A clutch includes an elastic member and an engaging portion for bringing the transmission and an engine into engagement with each other by an elastic reaction force of the elastic member. The elastic member has a gradient-decreasing range in which a gradient of a change in elastic load with respect to deformation of the elastic member decreases as the deformation increases. The gradient-decreasing range is included in a use range of the elastic member determined by operation of the clutch.
In one implementation, the elastic member is configured so that the entirety of the use range is the gradient-decreasing range.
According to another embodiment of the invention, an automatic clutch mechanism shifts gears while disengaging a clutch in conjunction with one pedal operation. A transmission shifts gears in conjunction with pedal operation. A clutch includes an elastic member and an engaging portion for bringing the transmission and an engine into engagement with each other by an elastic reaction force of the elastic member. The elastic member has an elastic-load-decreasing range in which an elastic load with respect to deformation of the elastic member decreases as the deformation increases. The elastic-load-decreasing range is included in a use range of the elastic member determined by operation of the clutch.
In one implementation, the elastic member is configured so that the entirety of the use range is the elastic-load-decreasing range.
The automatic clutch mechanism may be configured so that the clutch includes a release mechanism for operation in conjunction with pedal operation. The elastic member engages with the engaging portion and the release mechanism. Due to operation of the release mechanism, a part of the elastic member engaging with the engaging portion is displaced relative to a part of the elastic member engaging with the release mechanism, and the elastic member exerts the elastic load.
In one implementation, the clutch is a multiplate clutch in which a friction plate and a clutch plate are overlaid together in a staggered fashion and a pressure plate is overlaid on one side thereof. The elastic member is a generally disc-shaped leaf spring. The automatic clutch mechanism further includes a mounting member that causes a radially intermediate position of an outer surface of the leaf spring in a natural state to abut against the pressure plate of the clutch, and engages with a radially outer part of the leaf spring with respect to the intermediate position of the leaf spring. The mounting member is configured to mount the leaf spring to the clutch by moving the radially outer part toward the pressure plate, and a release mechanism that engages with a radially inner part of the leaf spring with respect to the intermediate position of the leaf spring, and operates in conjunction with the pedal operation to move the radially inner part to a side opposite to the pressure plate.
The leaf spring may be configured so that a distance from the radially outer part engaging with the mounting member to the radially inner part engaging with the release mechanism is larger than a distance from the radially outer part engaging with the mounting member to the intermediate position abutting against the pressure plate. Further, the leaf spring may be, for example, a generally conical spring.
The release mechanism may include a pedal shaft rotatable in conjunction with a pedal; a conversion mechanism including an output member that outputs linear motion on the basis of rotation of the pedal shaft; a pushing member that abuts against the radially inner part of the conical spring, and moves linearly in conjunction with linear motion of the output member to push the conical spring away from the pressure plate; and a lever member having a fulcrum swingably supported on a fixing member, a force point at which linear motion is inputted from the output member, and an action point at which linear motion is outputted to the pushing member.
The lever member may be configured so that a distance from the fulcrum to the action point is larger than a distance from the fulcrum to the force point.
Another embodiment of the invention provides an automatic clutch mechanism for a straddle-type vehicle for shifting gears while disengaging a clutch in conjunction with one pedal operation. A transmission shifts gears in conjunction with pedal operation. A clutch includes an elastic member and an engaging portion for bringing the transmission and an engine into engagement with each other by an elastic reaction force of the elastic member. A mounting member mounts the elastic member in position by causing the elastic member to elastically deform while being abutted against the engaging portion of the clutch. A release mechanism releases the clutch by deforming the elastic member while engaging with the elastic member. The elastic member is configured so that a distance from a part of the elastic member abutted against the mounting member to a part of the elastic member engaging with the release mechanism is larger than the part of the elastic member abutted against the mounting member to a part of the elastic member abutted against the engaging portion of the clutch.
The elastic member may be a leaf spring, and the leaf spring may be a generally conical spring.
In one implementation, the automatic clutch mechanism is configured so that the elastic member is a generally conical spring. The release mechanism includes a pedal shaft rotatable in conjunction with a pedal; a conversion mechanism including an output member that outputs linear motion on the basis of rotation of the pedal shaft; a pushing member that abuts against the radially inner part of the leaf spring, and moves linearly in conjunction with linear motion of the output member to push the leaf spring away from a pressure plate; and a lever member having a fulcrum swingably supported on a fixing member, a force point at which linear motion is inputted from the output member, and an action point at which linear motion is outputted to the pushing member.
The lever member may be configured so that a distance from the fulcrum to the action point is larger than a distance from the fulcrum to the force point.
A straddle-type vehicle according to the present invention includes any of the automatic clutch mechanisms mentioned above.
With the automatic clutch mechanism of the invention, the reaction force exerted on the pedal becomes generally small in comparison with the related art, and thus the burden on the rider during pedal operation is reduced, thereby making it easier for the rider to operate the pedal. When the clutch is disengaged by operating the pedal and a gear shift is performed, the reaction force exerted on the pedal becomes generally small in comparison with the related art. Therefore, at the time of gear shifting, the change in the reaction force exerted on the pedal is readily transmitted to the rider through the pedal.
Other features and advantages of the invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, various features of embodiments of the invention.
FIGS. 11(a)-(d) are plan views of a modification of a conical spring (elastic member) according to an embodiment of the present invention.
The inventors wish to improve the operability of a pedal in an automatic clutch mechanism by making the reaction force exerted on the pedal as small as possible. Further, the inventors believe that transmitting the feel of gear shifting to the rider through the pedal will make the steering of a straddle-type vehicle more fun. Thus, the inventors examined improvements that could be made to automatic clutch mechanisms according to the related art. The inventors considered the mechanism of the reaction force exerted on the pedal, and the reason why the feel of gear shifting is not readily transmitted to the rider through the pedal, as follows.
As shown in
As indicated by broken line A, although the reaction force exerted on pedal 11 is small at the time when starting the operation of pedal 11, as the operating angle of pedal 11 is increased, the structural play becomes smaller, and the reaction forces applied from respective mechanisms gradually increase. In automatic clutch mechanism 10, release mechanism 23 of clutch 12 is operated first, and transmission 13 is operated after clutch 12 is disengaged. Accordingly, the timing at which transmission 13 is operated by transmission operating mechanism 24 is adjusted.
In the automatic clutch mechanism of the related art, in particular, elastic member 21 inserted in clutch 12 has such a characteristic that its elastic load increases generally in proportion to an increase in elastic deformation as shown in
A particularly characteristic feature of the reaction force (pedal load) exerted on pedal 11 from transmission 13 is the change in reaction force at the time of gear shifting. That is, although not shown, at the time of gear shifting, a gear provided on the drive shaft is temporarily disengaged from a gear provided on the main shaft (gear disengagement). As indicated by broken line A in
The inventors considered the mechanism of the reaction force exerted on the pedal, and the reason why the feel of gear shifting is not readily transmitted to the rider through the pedal. The inventors have thus developed a completely novel automatic clutch mechanism that allows the feel of gear shifting to be readily transmitted to the rider through pedal 11.
An embodiment of the invention is now described with reference to the drawings.
JP Patent Applications Hei 8-15044 and 2004-19936 are incorporated herein for reference. The invention is not limited to the embodiment described below.
Automatic clutch mechanism 10 according to this embodiment shifts gears while disengaging clutch 12 in conjunction with one pedal operation. As shown in
The above-mentioned gradient-decreasing range is included in the use range of elastic member 21. Therefore, as indicated by solid line B in
Automatic clutch mechanism 10 according to this embodiment is now described in more detail.
In this embodiment, as shown in
The longitudinal section of generally conical spring 21 is schematically shown in
The elastic load with respect to deformation amount of conical spring 21 is shown in
In this case, the gradient of a change in elastic load with respect to deformation of elastic member 21 may be considered on the basis of the graph of
As shown in
As shown in
Therefore, as indicated by solid line B in
Clutch 12 of automatic clutch mechanism 10, and the arrangement structure of conical spring 21, is now further described.
As shown in
As shown in
When disengaging clutch 12, as shown in
In this embodiment, the natural state of conical spring 21 refers to a state in which no external force is being exerted on conical spring 21. Further, the “use range of the elastic member” refers to the deformation range of the conical spring from the state in which conical spring 21 is incorporated into clutch 12 as shown in
As shown in
Since the principle of leverage is used for the arrangement structure of conical spring 21, release mechanism 23 can be operated with less force in comparison with the elastic reaction force of conical spring 21 exerted on pressure plate 33.
Although conical spring 21 undergoes further deformation as release mechanism 23 operates against conical spring 21, the elastic reaction force from conical spring 21 does not become larger in comparison with the related art. Consequently, when pedal 11 is operated and clutch 12 operates due to release mechanism 23, the reaction force exerted on pedal 11 at this time due to the elastic reaction force of elastic member 21 inserted in clutch 12 becomes generally small in comparison with the related art.
Accordingly, when automatic clutch mechanism 10 is adopted for a straddle-type vehicle, the reaction force exerted on pedal 11 when gears are shifted by operating pedal 11 to engage/disengage clutch 12 becomes generally small in comparison with the related art. Therefore, at the time of gear shifting, the change in the reaction force exerted on pedal 11 is readily transmitted to the rider through pedal 11. Since the reaction force exerted on pedal 11 becomes generally small in comparison with the related art, the burden placed on the rider during pedal operation can be reduced as well.
The distance from radially outer part 42 engaging with mounting member 34 to radially inner part 43 engaging with release mechanism 23 is set larger than the distance from radially outer part 42 engaging with mounting member 34 to intermediate position 41 in abutment with pressure plate 33. That is, conical spring 21 utilizes the principle of leverage with its radially outer part engaged with mounting member 34 serving as a fulcrum, its radially outer part engaged with release mechanism 23 serving as a force point, and point 41 in abutment with pressure plate 33 serving as an action point. This allows release mechanism 23 to disengage clutch 12 by pressing conical spring 21 with less force.
As described above, conical spring 21 is used as the elastic member, and the principle of leverage is utilized for the arrangement structure of conical spring 21, thereby making the reaction force exerted on pedal 11 small.
In this embodiment, the release mechanism is also contrived as follows.
Since the above-described structure utilizes the principle of leverage for the arrangement structure of conical spring 21, the amount of movement of the point (action point) at which conical spring 21 is in abutment with pressure plate 33 is small relative to the amount of movement of radially inner part 43 (force point) of conical spring 21 engaging with release mechanism 23. To ensure reliable disengagement of clutch 12, the point (action point) at which conical spring 21 is in abutment with pressure plate 33 must be moved by a predetermined distance. Achieving this by increasing the operating angle of pedal 11 is not desirable since the operating angle of pedal 11 has been adjusted to about 20 degrees (in this embodiment, 18 degrees) by taking the operability for the rider into consideration.
In view of this, as shown in
By utilizing the principle of leverage for release mechanism 23, pushing member 52 that abuts against conical spring 21 can be moved by a predetermined distance in accordance with operation of pedal 11, without changing the operating angle of pedal 11.
The distance from the fulcrum to the action point in lever member 53 is set to be larger than the distance from the fulcrum to the force point. The movable distance of pushing member 52 abutted against conical spring 21 can be thus increased without changing the operating angle of pedal 11. This ensures reliable clutch disengagement also in the case where the principle of leverage is utilized for the arrangement structure of conical spring 21 as described above.
The structure of release mechanism 23 is now described in more detail.
As shown in
Pushing member 52 includes a first rod 91, a ball 92, and a second rod 93 that are inserted in hollow main shaft 37 of transmission 13. First rod 91 projects to lever member 53 side from main shaft 37. Ball 92 is held between first rod 91 and second rod 93. Ball 92 is a member for transmitting axial motion between first rod 91 and second rod 93 without transmitting rotation. The distal end portion of second rod 93 which projects from main shaft 37 radially diverges to prevent detachment from main shaft 37. An arm portion 94 extends radially outwards from the distal end of second rod 93. Arm portion 94 is in abutment with the inner surface (surface abutting against pressure plate 33) of radially inner part 43 of conical spring 21 in the natural state.
Lever member 53 is a member that is swingably supported on fixing member 64 fixedly disposed in housing 84 in a fixed manner. One side of lever member 53 abuts against output member 62 of conversion mechanism 51, and the other side thereof abuts against an end of first rod 91 of pushing member 52. The point swingably supported on fixing member 64 serves as fulcrum 71, the point in abutment with output member 62 serves as force point 72, and the point in abutment with pushing member 52 serves as action point 73.
When the rider operates pedal 11, pedal shaft 61 and input member 81 rotate, and the positions of depressions 81a, 82a of input member 81 and conversion member 82 are circumferentially shifted. When the positions of depressions 81a, 82a of input member 81 and conversion member 82 are shifted, ball 83 held between depressions 81a, 82a of input member 81 and conversion member 82 move while rolling so as to dislodge from depressions 81a, 82a. At this time, since input member 81 is fixed to pedal shaft 61, and the rotation of conversion member 82 is restricted by shaft 85, as ball 83 rolls so as to dislodge from depressions 81a, 82a, conversion member 82 moves to the left side in
As output member 62 moves to the left side in
As described above, lever member 53 is interposed in release mechanism 23 to transmit the motion of output member 62 to pushing member 52, thereby moving pushing member 52 by a required distance. This also makes it possible, for example, to largely move pushing member 52 relative to the movement of output member 62. As described above, the principle of leverage is utilized when disposing conical spring 21, and is also utilized for release mechanism 23, thereby ensuring more reliable operation of clutch 12.
In this embodiment, transmission operating mechanism 24 (see
While an automatic clutch mechanism according to an embodiment of the present invention has been described, the automatic clutch mechanism according to the invention is not limited to the described embodiment.
For example, according to the foregoing description, by taking into consideration the gradient of a change in elastic load with respect to deformation of elastic member 21, elastic member 21 of clutch 12 has the gradient-decreasing range in which the gradient decreases as the deformation of the elastic member 21 increases. Further, the gradient-decreasing range is included in the use range of elastic member 21 determined by operation of clutch 12.
The elastic characteristic of elastic member 21 is not limited to the one shown in
Elastic member 21 of clutch 12 can be also evaluated on the basis of the elastic load with respect to deformation of elastic member 21. That is, as shown in
Since the elastic-load-decreasing range is included in the use range of the elastic member, as shown in
In the above-described embodiment, as shown in
While in the above-described embodiment a generally conical spring is used as the elastic member, the configuration of the conical spring can be modified in various ways in accordance with the structure of the clutch. For example, as shown in
Further, while a conical spring has been described as an example of elastic member, the elastic member is not limited to a conical spring or leaf spring. Any elastic member (elastic body) may be inserted in the clutch of the automatic clutch mechanism according to the present invention as long as it includes the gradient-decreasing range or elastic-load-decreasing range as described above. Examples include an air spring whose elastic characteristic can be changed in accordance with the amount of air. Further, the elastic member used may be a coil spring as long as it is provided with the gradient-decreasing range or elastic-load-decreasing range as described above, such as through combination of coil springs of different elastic characteristics. The structure of the clutch may be modified as appropriate in accordance with the configuration of the elastic member. The structure of the clutch or release mechanism may also be altered as appropriate. In the case where an air spring or coil spring is adopted for the elastic member, the following structure may be adopted. That is, the automatic clutch mechanism includes a release mechanism that operates in conjunction with a pedal operation, the elastic member engages with each of the engaging portion and the release mechanism, and as the release mechanism operates, the part of the elastic member engaging with the release mechanism is displaced relative to the part engaging with the engaging portion and an elastic load is exerted.
Automatic clutch mechanism 10 according to the embodiment includes transmission 13 for shifting gears in conjunction with a pedal operation, clutch 12 including elastic member 21 and engaging portion 22 for bring transmission 13 and the engine into engagement with each other in response to the elastic reaction force of elastic member 21, mounting member 34 for mounting elastic member 21 in position by causing elastic member 21 to undergo elastic deformation while being abutted against engaging portion 22 of clutch 12, and release mechanism 23 for releasing clutch 12 by deforming elastic member 21 while engaging with elastic member 21. In elastic member 21, the distance from the part abutted against mounting member 34 to the part engaged with release mechanism 23 is set larger than the distance from the part abutted against mounting member 34 to the part abutting against engaging portion 22 of clutch 12.
Due to the arrangement structure of elastic member 21 as described above, the reaction force exerted on the pedal due to the elastic reaction force of elastic member 21 becomes generally small in comparison with the related art, thereby reducing the burden on the rider during pedal operation. Further, the reaction force exerted on pedal 11 due to the elastic reaction force of elastic member 21 becomes small, and at the time of gear shifting, the change in the reaction force exerted on the pedal is readily transmitted to the rider through the pedal. Therefore, the above-described automatic clutch mechanism is suitable for use as the automatic clutch mechanism for a straddle-type vehicle. A substantially conical spring can be used as elastic member 21.
As described above, the present invention provides a straddle-type vehicle with an automatic clutch mechanism that more readily transmits the feel of gear shifting to the rider via the pedal as compared with the related art.
The particular embodiments of the invention described in this document should be considered illustrative, rather than restrictive. Modification to the described embodiments may be made without departing from the spirit of the invention as defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-212621 | Aug 2006 | JP | national |
