Patent Publication Number: US-11022211-B2

Title: Vehicle shift control device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The disclosure of Japanese Patent Application No. 2016-159098 filed on Aug. 15, 2016, including specification, drawings and claims is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The disclosure relates to a vehicle shift control device. 
     BACKGROUND 
     In recent years, a motorcycle mounted with an automatic manual transmission (AMT) or a dual clutch transmission (DCT) as a transmission device having both excellent mechanical efficiency derived from a manual transmission and convenience derived from an automatic transmission has been increasingly used. The AMT is provided with a shift actuator for use in a shift operation. The shift actuator is configured to be driven in response to a shifting operation on an operation pedal and to perform shift control in a shift mechanism. 
     In the related art, there is suggested a shift control device for a saddle-ridden type vehicle in which a moveable range of an operation pedal and a moveable range of a moveable part such as a click mechanism are offset in a width direction of the vehicle and the operation pedal and the moveable part are arranged so as to come close to each other (for example, refer to Patent Document 1). In such a shift control device, it is possible to closely arrange the moveable part and the operation pedal while avoiding any interference therebetween upon operation thereof. Accordingly, it is possible to reduce a space occupied by the moveable part and the operation pedal, to increase layout properties of an engine and a vehicle body.
     Patent Document 1: Japanese Patent No. 5,722,165 (Specification and FIG. 6)   

     However, according to the shift control device disclosed in Patent Document 1, the moveable range of the operation pedal and the moveable range of the moveable part are offset in the width direction of the vehicle. For this reason, a dimension of the entire shift detection mechanism in the width direction of the vehicle increases. 
     SUMMARY 
     It is therefore an object of the disclosure to provide a vehicle shift control device capable of shortening a dimension of a shift detection mechanism in a width direction of a vehicle. 
     According to an aspect of the embodiments of the present invention, there is provided a vehicle shift control device comprising: a shift mechanism configured to shift and transmit rotation of a crankshaft extending in a width direction of a vehicle to a driving wheel; a shift pedal configured to receive a shifting operation for the shift mechanism; a shift detection mechanism configured to detect a shift instructed via the shift pedal; and a shift actuator configured to perform a shift operation of the shift mechanism, in response to a detection content of the shift detection mechanism, wherein the shift detection mechanism comprises a detection unit configured to rotate in response to the shifting operation of the shift pedal and a sensor configured to detect rotation of the detection unit, and a rotary shaft of the detection unit and a rotary shaft of the sensor are arranged at different positions, as seen from a side. 
     According to the above configuration, since the rotary shaft of the detection unit configured to rotate in response to the shifting operation of the shift pedal and the rotary shaft of the sensor configured to detect the rotation of the detection unit are arranged at the different positions, as seen from the side, it is possible to shorten a dimension of the shift detection mechanism in the width direction of the vehicle, as compared to a configuration in which the rotary shafts are coaxially arranged. 
     In the vehicle shift control device, the shift detection mechanism may comprise a cover configured to accommodate therein the detection unit, and the cover may be mounted to a sprocket cover. According to the above configuration, since the cover configured to accommodate therein the detection unit is mounted to the sprocket cover, the sprocket cover and the cover of the shift detection mechanism are arranged outside the drive chain. With the double structure of the sprocket cover and the cover, it is possible to achieve a sound deadening effect and to reduce a driving sound caused due to the rotation of the drive chain. 
     In the vehicle shift control device, the sensor may be arranged outside the cover. According to the above configuration, since the sensor configured to detect the rotation of the detection unit is arranged in the space different from the detection unit with the cover being interposed therebetween, it is possible to prevent a situation where the sensor is to be damaged due to foreign matters involved by the drive chain. 
     In the vehicle shift control device, the shift mechanism may be arranged below a counter shaft which is arranged behind the crankshaft in parallel with the crankshaft. According to the above configuration, since the shift mechanism is arranged below the counter shaft, even when the vehicle shift control device according to the disclosure is applied to a vehicle in which the shift actuator and the like are not provided, it is possible to approximate the extending direction of the shift pedal. Accordingly, it is possible to apply the disclosure to a vehicle having a different specification without considerably changing a layout. 
     The vehicle shift control device may further comprise: a clutch mechanism provided at one end of the counter shaft and configured to transmit and disconnect rotation of the crankshaft to and from the counter shaft; and a clutch actuator configured to perform a disconnection/connection operation of the clutch mechanism, the detection unit may be arranged behind the clutch actuator, and the sensor may be arranged between the clutch actuator and the detection unit. According to the above configuration, the sensor of the shift detection mechanism is arranged in the vicinity of the clutch actuator. Accordingly, it is possible to arrange the sensor in the vicinity of the clutch actuator and inside an outer end face of the clutch actuator. Consequently, it is possible to protect the sensor which is susceptible to a shock and the like, by the clutch actuator. 
     According to the disclosure, it is possible to shorten the dimension of the shift detection mechanism in the width direction of the vehicle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings: 
         FIG. 1  is a left side view illustrating a schematic configuration of a motorcycle to which a vehicle shift control device according to an illustrative embodiment of the present invention can be applied; 
         FIG. 2  is a left side view illustrating a configuration around an engine of the motorcycle according to the illustrative embodiment; 
         FIG. 3  is a side view of a surrounding of the engine of the motorcycle according to the illustrative embodiment; 
         FIG. 4  is a perspective view of the surrounding of the engine of the motorcycle according to the illustrative embodiment; 
         FIG. 5  is a plan view of the surrounding of the engine of the motorcycle according to the illustrative embodiment; 
         FIG. 6  is a front view of the surrounding of the engine of the motorcycle according to the illustrative embodiment; 
         FIG. 7  is a rear view of the surrounding of the engine of the motorcycle according to the illustrative embodiment; 
         FIG. 8  is a perspective view of a clutch actuator provided in the motorcycle according to the illustrative embodiment; 
         FIG. 9  is a perspective view of a shift actuator provided in the motorcycle according to the illustrative embodiment; 
         FIG. 10  is a perspective view of a link mechanism that is to be coupled to a shift mechanism provided in the motorcycle according to the illustrative embodiment; 
         FIG. 11  is a perspective view of the link mechanism that is to be coupled to the shift mechanism provided in the motorcycle according to the illustrative embodiment; 
         FIG. 12  is an enlarged view of a surrounding of a shift detection mechanism provided in the motorcycle according to the illustrative embodiment; 
         FIG. 13  is a perspective view of a surrounding of a shift detection unit within the shift detection mechanism provided in the motorcycle according to the illustrative embodiment; 
         FIG. 14A  is a front view of the shift detection unit within the shift detection mechanism provided in the motorcycle according to the illustrative embodiment; 
         FIG. 14B  is a side view of the shift detection unit within the shift detection mechanism provided in the motorcycle according to the illustrative embodiment; 
         FIG. 15  is a side view of the surrounding of the shift detection mechanism provided in the motorcycle according to the illustrative embodiment; 
         FIG. 16  is a plan view of a surrounding of the shift detection mechanism and the link mechanism provided in the motorcycle according to the illustrative embodiment; 
         FIG. 17  is a front view of the surrounding of the shift detection mechanism and the link mechanism provided in the motorcycle according to the illustrative embodiment; and 
         FIGS. 18A and 18B  are side views of the link mechanism provided in the motorcycle according to the illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, an illustrative embodiment of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, a motorcycle of a sports type will be described as an example of an object to which the motorcycle according to the present invention can be applied. However, the type of the motorcycle is not limited thereto and can be changed. For example, the present invention can also be applied to a two-wheeled vehicle of the other type, a three-wheeled vehicle of a buggy type, a four-wheeled vehicle and the like. 
     A schematic configuration of a motorcycle according to the illustrative embodiment is described with reference to  FIGS. 1 and 2 .  FIG. 1  is a left side view illustrating a schematic configuration of a motorcycle to which a vehicle shift control device according to an illustrative embodiment can be applied.  FIG. 2  is a left side view illustrating a configuration around an engine of the motorcycle according to the illustrative embodiment. Hereinafter, as to the directions, a front side of the motorcycle is denoted with an arrow FR, a rear side of the motorcycle is denoted with an arrow RE, a left side of the motorcycle is denoted with an arrow L, and a right side of the motorcycle is denoted with an arrow R. Also, in the respective drawings, some of the configurations may be omitted for convenience of explanations. 
     As shown in  FIG. 1 , the motorcycle  1  comprising a vehicle body frame  2  mounted with a power unit, an electric system and the like and an engine  3  mounted on the vehicle body frame  2 . The engine  3  is, for example, a parallel four-cylinder engine. As described in detail later, the engine  3  is configured by mounting a cylinder  31 , a cylinder head  32  and a cylinder head cover  33  to an upper part of an engine case (a crankcase)  30  accommodating therein a crankshaft  301  (not shown in  FIG. 1 , refer to  FIG. 2 ). A lower part of the engine case  30  is provided with an oil pan  34 . As described in detail later, the engine case  30  is provided with an automatic manual transmission device (AMT)  40 . 
     The vehicle body frame  2  is a twin-spar type frame made of aluminum cast. As described above, the vehicle body frame  2  is configured to secure the entire strength of the vehicle body by mounting the engine  3  thereon. The vehicle body frame  2  as a whole extends rearwards from the front side of the motorcycle, and has a shape curved downwards at a rear end-side thereof. 
     Specifically, the vehicle body frame  2  has a head frame  21  bifurcating from a head pipe  20  into the right and left sides and extending rearwards, a pair of right and left tank rails  22  obliquely extending downwards towards the rear side from the head frame  21 , and a body frame  23  extending downwards from rear ends of the tank rails  22 . 
     The head frame  21  and the tank rails  22  are provided on lower surfaces thereof with a pair of right and left bracket parts  21   a . The bracket parts  21   a  are configured to support a front part (a cylinder head  31 ) of the engine  3 . Each of the tank rails  22  has a cylinder shape having a hollow sectional shape. A fuel tank  4  is arranged above the tank rails  22 . 
     The body frame  23  is configured by coupling upper and lower end portions of a pair of frame parts  23   a  extending downwards from the rear ends of the respective tank rails  22  in a width direction of the motorcycle. A rear part of the engine  3  (a rear part of the crankcase  30 ) is supported by the upper and lower end portions of the body frame  23 . A substantially central part of the body frame  23  in a vertical direction is provided with a swing arm pivot  23   b  configured to swingably support a swing arm  5 . A rider seat  6  connected to the fuel tank  4  is provided above the frame parts  23   a.    
     The vehicle body frame  2  configured as described above and the engine  3  are mounted with a variety of covers  7  as an exterior package of the vehicle body. Specifically, the front part of the vehicle body is covered by a front cowl  70 , and the rear part and the lower part of the rider seat  6  are covered by a real cowl  71 . The front part and the side part of the engine  3  are covered by an under cowl  72 . In  FIG. 1 , the under cowl  72  provided at the left side of the vehicle body is omitted for convenience of explanations. 
     A pair of right and left front forks  8  are supported by the head pipe  20  via a steering shaft (not shown) in a steerable manner. A front wheel  9  is rotatably supported by lower end portions of the front forks  8 . An upper part of the front wheel  9  is covered by a front fender  10 . 
     The swing arm  5  extends rearwards from the swing arm pivot  23   b . A rear suspension (not shown) is provided between the swing arm  5  and the body frame  23 . A rear wheel  11  is rotatably supported by a rear end of the swing arm  5 . An upper part of the rear wheel  11  is covered by a rear fender  12  provided on a lower surface of the real cowl  71 . 
     Exhaust pipes  13  and a muffler  14  are connected to respective exhaust ports of the cylinder head  31 . The plurality of exhaust pipes  13  extend downwards from the respective exhaust ports, are bent rearwards below the engine  3  and are integrated into one. The muffler  14  is connected to a downstream end of the exhaust pipes  13 . Exhaust gas generated due to combustion of the engine  3  is introduced into the muffler  14  via the exhaust pipes  13 . Then, an exhaust sound of the exhaust gas is reduced by the muffler  14 , and the exhaust gas is discharged outside. 
     Configurations around the engine  3  of the motorcycle  1  according to the illustrative embodiment are described. As shown in  FIG. 2 , the crankshaft  301 , a counter shaft  302  and a drive shaft  303  extending in the width direction of the motorcycle (a direction orthogonal to the paper surface of  FIG. 2 ) are pivotally supported by the engine case  30 . The crankshaft  301  is arranged below the cylinder  31 . The counter shaft  302  is arranged behind the crankshaft  301 . The drive shaft  303  is arranged behind the counter shaft  302 . 
     A generator (not shown) is connected to a left end portion of the crankshaft  301 . The generator is configured to generate a power as the motorcycle travels and to supply the generated power to in-vehicle devices or a battery (not shown). Also, a clutch mechanism (not shown) is connected to a right end portion of the counter shaft  302 . The clutch mechanism is configured to transmit and disconnect rotation of the crankshaft  301  to and from the counter shaft  302 . The generator and the clutch mechanism are respectively accommodated in a mug cover  35  and a clutch cover  36  (regarding the clutch cover  36 , refer to  FIG. 7 ). The mug cover  35  and the clutch cover  36  are mounted to the engine case  30 . 
     A shift mechanism  37  is arranged below the counter shaft  302  and the drive shaft  303 . The shift mechanism  37  is configured to shift the rotation of the crankshaft  301  and to transmit the rotation of the crankshaft to the rear wheel  11 . A water pump  38  is provided in front of the shift mechanism  37 . The water pump  38  is mounted to a radiator via a radiator hose  39  and is configured to circulate cooling water for cooling the engine  3 . Meanwhile, in  FIG. 2 , for convenience of explanations, the radiator hose  39  connected to the water pump  38  is omitted (refer to  FIG. 3 ). 
     The engine case  30  is provided with an automatic manual transmission (AMT)  40 . The AMT  40  includes the clutch mechanism, the shift mechanism  37 , a clutch actuator  41  and a shift actuator  42 . The clutch actuator  41  is configured to perform a disconnection/connection operation of the clutch mechanism. The shift actuator  42  is configured to perform a shift operation of the shift mechanism  37 . 
     Hereinafter, an arrangement of the clutch actuator  41  and the shift actuator  42  constituting the AMT  40  is described with reference to  FIGS. 3 to 7 . Hereinafter, a case where the clutch actuator  41  and the shift actuator  42  are arranged around the mug cover  35  is described. As described above, the clutch actuator  41  and the shift actuator  42  may also be arranged around the clutch cover  36 . 
       FIG. 3  is a side view of a surrounding of the engine  3  of the motorcycle  1  according to the illustrative embodiment.  FIG. 4  is a perspective view of the surrounding of the engine  3  of the motorcycle  1  according to the illustrative embodiment.  FIG. 5  is a plan view of the surrounding of the engine  3  of the motorcycle  1  according to the illustrative embodiment.  FIGS. 6 and 7  are a front view and a rear view of the surrounding of the engine  3  of the motorcycle  1  according to the illustrative embodiment.  FIG. 4  illustrates the surrounding of the engine  3 , as seen from a front side of the motorcycle. Also, in  FIGS. 6 and 7 , the vehicle body frame  2  is shown for convenience of explanations. 
     As shown in  FIGS. 3 and 4 , the mug cover  35  has a disc-shaped part  351  having a substantial disc shape, as seen from a side, and a side surface part  352  extending inwards from a peripheral edge portion of the disc-shaped part  351  in the width direction of the motorcycle. The clutch actuator  41  and the shift actuator  42  are arranged around the disc-shaped part  351 , as seen from a side. In this case, the clutch actuator  41  and the shift actuator  42  are arranged along a circumferential direction of the disc-shaped part  351 , as seen from a side. 
     The clutch actuator  41  is arranged at a position behind the disc-shaped part  351  at the left of the engine case  30 , as seen from a side. The shift actuator  42  is arranged at a position above the disc-shaped part  351  at the left of the cylinder  31 , as seen from a side. The shift mechanism  37  is arranged behind the clutch actuator  41 , as seen from a side. The shift actuator  42  is arranged opposite (i.e., at a front side) to the shift mechanism  37  in the front and rear direction with the clutch actuator  41  being interposed therebetween. 
     As described in detail later, the clutch actuator  41  and the shift actuator  42  include motor units  411 ,  421  having substantially cylindrical shapes and speed reduction mechanisms  412 ,  422  coupled to the motor units  411 ,  421 , respectively. The clutch actuator  41  and the shift actuator  42  are arranged so that axial directions of the motor units  411 ,  421  extend in a direction (more specifically, a direction parallel with the front and rear direction of the motorcycle) orthogonal to the width direction of the motorcycle (a depth direction of the paper surface of  FIGS. 3 and 4 ). The clutch actuator  41  and the shift actuator  42  are arranged to face each other at the side surface part  352  of the mug cover  35 . 
     In the AMT  40  according to the illustrative embodiment, the clutch actuator  41  and the shift actuator  42  are arranged orthogonal to the width direction of the motorcycle. Consequently, it is possible to reduce a space required to arrange the clutch actuator  41  and the shift actuator  42 , in the width direction of the motorcycle. Thereby, it is possible to reduce a size of the engine  3  in the width direction of the motorcycle by making maximum use of the spaces around the mug cover  35 . 
     In the clutch actuator  41  and the shift actuator  42 , the speed reduction mechanisms  412 ,  422  are arranged at positions at a side of the vehicle body frame  2  which is arranged at the upper side (more specifically, positions at a side of the tank rails  22 ). The motor units  411 ,  421  are respectively arranged opposite to the vehicle body frame  2  with the speed reduction mechanisms  412 ,  422  being interposed therebetween. The motor units  411 ,  421  are configured to be detachable from the speed reduction mechanisms  412 ,  422  towards the opposite side to the vehicle body frame  2 . 
     The clutch actuator  41  is arranged so that an axial direction of the motor unit  411  extends in the upper and lower direction. The motor unit  411  is arranged below the speed reduction mechanism  412 . The shift actuator  42  is arranged so that an axial direction of the motor unit  421  extends in a slightly upward direction towards the rear. The motor unit  421  is arranged at a slightly downward position in front of the speed reduction mechanism  422 . That is, tip end portions (lower end portions) of the motor units  411 ,  421  are arranged to face towards the different directions. 
     In the AMT  40  according to the illustrative embodiment, the respective motor units  411 ,  421  are arranged opposite to the vehicle body frame  2  with the speed reduction mechanisms  412 ,  422  being interposed therebetween. Consequently, it is possible to improve the operation efficiency upon maintenance of the clutch actuator  41  and the shift actuator  42 . In particular, the motor units  411 ,  421  are configured to be detachable from the speed reduction mechanisms  412 ,  422  to the opposite side to the vehicle body frame  2 . Consequently, it is possible to attach and detach the motor units  411 ,  421  without interfering with the vehicle body frame  2  upon maintenance of the clutch actuator  41  and the shift actuator  42  and the like, so that it is possible to improve the operation efficiency. 
     As shown in  FIGS. 6 and 7 , the clutch actuator  41  and the shift actuator  42  are arranged inside an outer end face (a left end face) of the mug cover  35 . In  FIGS. 6 and 7 , a plane passing the outer end face of the mug cover  35  is denoted with a dotted line MC, for convenience of explanations. In this way, the clutch actuator  41  and the shift actuator  42  are arranged inside the outer end face of the mug cover  35  which has stiffness, so that it is possible to avoid a situation where the clutch actuator  41  and the shift actuator  42  comes in contact with a road surface or the like when the motorcycle  1  is turned over, for example. Consequently, it is possible to suppress a situation where the clutch actuator  41  and the shift actuator  42  are to be damaged. Also, it is possible to make it difficult for a driver or the like to come in contact with the actuators  41 ,  42 . 
     As shown in  FIG. 3 , a sprocket cover  50  is provided at the rear of the clutch actuator  41  above the shift mechanism  37 , as seen from a side. The sprocket cover  50  is configured to cover a sprocket on which a chain for transmitting a driving force to the rear wheel  11  is wound. The sprocket cover  50  is arranged inside the clutch actuator  41  in the width direction of the motorcycle, at the front of the body frame  23 . 
     The clutch actuator  41  is fixed to the sprocket cover  50 . As shown in  FIGS. 4 and 5 , the clutch actuator  41  is fixed from above to a flange part  501  which is arranged at an upper part of the sprocket cover  50 , with three screws  502   a  to  502   c  (the screws  502   b ,  502   c  are not shown in  FIG. 4 . Refer to  FIG. 5 ). The clutch actuator  41  is fixed to the flange part  501  at a part of the speed reduction mechanism  412 . The motor unit  411  is arranged so as to extend in the upper and lower direction outside the sprocket cover  50  (refer to  FIG. 4 ). 
     The shift actuator  42  is fixed to the mug cover  35 . As shown in  FIG. 4 , the shift actuator  42  is fixed from the left to bosses  353  which are arranged on a side surface of the mug cover  35 , with two screws  353   a ,  353   b . The shift actuator  42  is fixed to the bosses  353  at a part of the speed reduction mechanism  422 . The motor unit  421  is arranged so as to extend in the front and rear direction outside the mug cover  35  (refer to  FIG. 3 ). 
     In the illustrative embodiment, the clutch actuator  41  and the shift actuator  42  are mounted to the engine case  30  via the mug cover  35 . Consequently, it is possible to effectively reduce an influence of heat generated from the engine case  30  without providing a special member such as a bracket, which is required in the related art. 
     Configurations of the clutch actuator  41  and the shift actuator  42  are described with reference to  FIGS. 8 and 9 .  FIG. 8  is a perspective view of the clutch actuator  41  provided in the motorcycle  1  according to the illustrative embodiment.  FIG. 9  is a perspective view of the shift actuator  42  provided in the motorcycle  1  according to the illustrative embodiment. 
     As shown in  FIG. 8 , in the clutch actuator  41 , the speed reduction mechanism  412  is coupled to the upper part of the motor unit  411 . The speed reduction mechanism  412  has a pair of cases  412   a ,  412   b  which are superimposed in the upper and lower direction. In the cases  412   a ,  412   b , a plurality of speed reduction gears configured to mesh with each other are accommodated. Of the speed reduction gears, a gear arranged at the most upstream side is fixed to an output shaft of the motor unit  411  and is configured to rotate together with the output shaft of the motor unit  411 . Also, of the speed reduction gears, a gear arranged at the most downstream side is fixed to a release cam  413  and is configured to rotate the release cam  413 . The release cam  413  is configured to switch disconnection and connection of the clutch mechanism. 
     The clutch actuator  41  is provided with a rotation sensor  414  configured to detect rotation of the release cam  413 . As described above, the clutch actuator  41  is fixed to the sprocket cover  50  with the screws  502   a  to  502   c  (the screws  502   c  is not shown in  FIG. 8 ) arranged around the rotation sensor  414 . The motor unit  411  of the clutch actuator  41  is driven in response to an instruction from an ECU (not shown), so that the disconnection and connection of the clutch mechanism are switched through the rotation of the release cam  413 . The rotation sensor  414  can detect the disconnection and connection states of the clutch mechanism, in response to the rotation of the release cam  413 . 
     The shift actuator  42  has substantially the same configuration as the clutch actuator  41 . As shown in  FIG. 9 , in the shift actuator  42 , the speed reduction mechanism  422  is coupled to the upper part of the motor unit  421 . The speed reduction mechanism  422  has a pair of cases  422   a ,  422   b  which are superimposed in the upper and lower direction. The cases  422   a ,  422   b  are provided with bosses  422   c ,  422   d  arranged to face the bosses  353  of the mug cover  35 , respectively. The bosses  422   c ,  422   d  are arranged to face the bosses  353  of the mug cover  35 , which are then fastened with the screws  353   b ,  353   a , so that the shift actuator  42  is fixed to the mug cover  35  (refer to  FIG. 4 ). 
     In the cases  422   a ,  422   b , a plurality of speed reduction gears configured to mesh with each other are accommodated. Of the speed reduction gears, a gear arranged at the most upstream side is fixed to an output shaft of the motor unit  421  and is configured to rotate together with the output shaft of the motor unit  421 . Also, of the speed reduction gears, a gear arranged at the most downstream side is fixed to a first shift arm  423  and is configured to swing the first shift arm  423 . The first shift arm  423  is configured to axially move a link mechanism  370  coupled to the shift mechanism  37 . A configuration of the link mechanism  370  will be described later. 
     The shift actuator  42  has a swing sensor  425  configured to detect swing of the first shift arm  423 . The motor unit  421  is driven, in response to an instruction from the ECU (not shown), so that a shift of the shift mechanism  37  is switched through the swing of the first shift arm  423 . The swing sensor  425  can detect a shift state of the shift mechanism  37 , in response to the swing of the first shift arm  423 . 
     The configuration of the link mechanism  370  configured to couple the shift actuator  42  and the shift mechanism  37  is described.  FIGS. 10 and 11  are perspective views of the link mechanism  370  that is to be coupled to the shift mechanism  37  provided in the motorcycle  1  according to the illustrative embodiment.  FIG. 10  illustrates the link mechanism  370 , as seen from the rear of the motorcycle, and  FIG. 11  illustrates the link mechanism  370 , as seen from the front of the motorcycle. In  FIGS. 10 and 11 , the shift actuator  42  is also illustrated for convenience of explanations. 
     As shown in  FIGS. 10 and 11 , the link mechanism  370  has a link rod  371  and first and second pillow ball bearings  372 ,  373  arranged at both ends of the link rod  371 . The link rod  371  has a length capable of coupling the shift actuator  42  and the shift mechanism  37 . The link rod  371  extends substantially in the upper and lower direction, as seen from a side, extends with being slightly inclined towards the front of the motorcycle from the rear of the motorcycle (refer to  FIG. 3 ) and couples the shift mechanism  37  and the shift actuator  42 . In other words, the link rod  371  is configured to couple the shift actuator  42  arranged above the mug cover  35  and the shift mechanism  37  arranged below the counter shaft  302 . Consequently, it is possible to efficiently utilize the space separated in the upper and lower direction around the engine  3 . 
     The link rod  371  is coupled from the shift mechanism  37  to the shift actuator  42  through an inside of the clutch actuator  41  in the width direction of the motorcycle (refer to  FIG. 4 ). As the link rod  371  is arranged inside the clutch actuator  41 , the link rod  371  does not interfere with the maintenance operation of the clutch actuator  41  and the like. Consequently, it is possible to improve the operation efficiency upon the maintenance of the clutch actuator  41 . 
     The first pillow ball bearing (hereinafter, simply referred to as “first pillow ball”)  372  is rotatably coupled to the first shift arm  423  of the shift actuator  42 . The second pillow ball bearing (hereinafter, simply referred to as “second pillow ball”)  373  is rotatably coupled to the second shift arm  374  of the shift mechanism  37 . The second shift arm  374  is fixed to a shift shaft  375  supported by the shift mechanism  37  and is configured to be swingable about the shift shaft  375  (refer to  FIG. 10 ). The shift shaft  375  is configured to be rotatable in conjunction with the swing of the second shift arm  374 . 
     In the first pillow ball  372 , a pillow ball (not shown) is accommodated. The pillow ball is kept to be rotatable in an arrow A-B direction shown in  FIG. 10 , about a coupling shaft  423   a  to the first shift arm  423 , as a rotation center. Likewise, in the second pillow ball  373 , a pillow ball (not shown) is accommodated. The pillow ball is kept to be rotatable in an arrow C-D direction shown in  FIG. 10 , about a coupling shaft  374   a  (refer to  FIG. 11 ) to the second shift arm  374 , as a rotation center. 
     As shown in  FIGS. 10 and 11 , a coupling direction of the first pillow ball  372  with respect to the first shift arm  423  and a coupling direction of the second pillow ball  373  with respect to the second shift arm  374  are arranged to be orthogonal to each other. That is, the first pillow ball  372  is coupled to the first shift arm  423  towards the rear of the motorcycle, whereas the second pillow ball  373  is coupled to the second shift arm  374  towards the width direction of the motorcycle. When the first shift arm  423  swings in an E-F direction shown in  FIG. 11  in conjunction with the driving of the motor unit  421 , the second shift arm  374  swings in an G-H direction shown in  FIG. 11 . In this way, as the coupling direction of the first pillow ball  372  and the coupling direction of the second pillow ball  373  are arranged to be orthogonal to each other, it is possible to appropriately transmit the swing operation of the first shift arm  423  to the second shift arm  374  extending in the orthogonal direction. 
     In the illustrative embodiment, the shift mechanism  37  and the shift actuator  42  are coupled with each other by the link mechanism  370 . By using the link mechanism  370 , it is possible to flexibly utilize the separated space around the engine  3 . Particularly, in the illustrative embodiment, the link mechanism  370  includes the link rod  371  and the pair of pillow balls (the first and second pillow balls  372 ,  373 ) and the rotation axis of one of the pair of pillow balls (the first pillow ball  372 ) is arranged to be orthogonal to the rotation axis of the other of the pair of pillow balls (the second pillow ball  373 ). Accordingly, it is possible to arrange the output shaft of the shift actuator  42  and the shift shaft  375  of the shift mechanism  37  to be orthogonal to each other. Consequently, it is possible to flexibly select the spaces in which the shift actuator  42  and the shift mechanism  37  are to be arranged. 
     As shown in  FIG. 3 , a shift detection mechanism  51  is provided outside (the left side) the sprocket cover  50 . The shift detection mechanism  51  is configured to detect a shift change instruction that is to be input from a shift pedal  52 . The shift pedal  52  is swingably supported by a footrest bracket  54  (refer to  FIG. 12 ). The shift detection mechanism  51  is provided with a shift sensor  511  configured to detect a swing operation of a link arm  531  of a link mechanism  53  (which will be described later). The shift sensor  511  is configured to detect a shift change instruction from a driver by detecting the swing operation of the link arm  531 . 
     The configuration of the shift detection mechanism  51  is described with reference to  FIGS. 12, 13, 14A, and 14B .  FIG. 12  is an enlarged view of a surrounding of the shift detection mechanism  51  provided in the motorcycle  1  according to the illustrative embodiment. In  FIG. 12 , for convenience of explanations, a cover  512  of the shift detection mechanism  51  is illustrated with a dashed-two dotted line, to show a shift detection unit  55  in the cover  512 .  FIG. 13  is a perspective view of a surrounding of the shift detection unit  55  in the shift detection mechanism  51  provided in the motorcycle  1  according to the illustrative embodiment.  FIG. 14A  is a front view of the shift detection unit  55  in the shift detection mechanism  51  provided in the motorcycle  1  according to the illustrative embodiment.  FIG. 14B  is a side view of the shift detection unit  55  in the shift detection mechanism  51  provided in the motorcycle  1  according to the illustrative embodiment. 
     As shown in  FIG. 12 , the shift detection mechanism  51  has a cover  512  having a space therein. The cover  512  has a substantially rectangular shape, as seen from a side, and is fixed at four corners thereof to the sprocket cover  50  (refer to  FIG. 15 ). A shift sensor  511  is provided outside the cover  512  and at a lower part, at a side surface, and at the front side of the motorcycle. Also, the link arm  531  of the link mechanism  53  (which will be described later) is provided outside the cover  512  and at a lower part, at the side surface, and in the vicinity of the center. The link arm  531  is fixed to a link shaft  551  of a shift detection unit  55  (which will be described later), and is configured to be swingable about the link shaft  551 . 
     In the cover  512 , the shift detection unit (a detection unit)  55  is accommodated. In the cover  512 , the shift detection unit  55  is fixed to a side surface of the sprocket cover  50  via the cover  512  with a pair of screws  552   a ,  552   b . The shift detection unit  55  is provided with a pair of first and second shift plates  553 ,  554  through which the link shaft  551  passes. 
     The first and second shift plates  553 ,  554  have a substantially flat plate shape, respectively, and are arranged to face each other with a predetermined interval in the width direction of the motorcycle (refer to  FIGS. 14A, 14B, and 15 ). As shown in  FIG. 14A , the first and second shift plates  553 ,  554  are arranged to partially overlap with each other, as seen from a side. The second shift plate  554  has a shape protruding downwards from the first shift plate  553 , as seen from a side. The screws  552   a ,  552   b  are arranged at the protruding part. 
     A cylindrical support shaft  555  is provided at a rear end portion of the first shift plate  553 . The support shaft  555  protrudes from an inner surface of the first shift plate  553  towards the second shift plate  554 . The support shaft  555  has a function of securing a distance between the first shift plate  553  and the second shift plate  554 . The support shaft  555  is not fixed to the second shift plate  554 . 
     In the support shaft  555 , a click mechanism (not shown) configured to cause a tactile feedback (a click feeling) in conjunction with rotation of the first shift plate  553  is accommodated. The click mechanism is configured by a coil spring and a ball member, for example. The ball member is pressed to the second shift plate  554  by an urging force of the coil spring. The second shift plate  554  is formed with a concave part for accommodating therein a part of the ball member in a state where the first shift plate  553  is arranged at an initial position. When the first shift plate  553  rotates, the ball member separates from the concave part, and when the first shift plate  553  returns to its initial position, the ball member enters the concave part, thereby causing the click feeling. 
     A front end portion of the first shift plate  553  is provided with a link member  556  coupled to a shaft part  511   a  of the shift sensor  511 . The link member  556  is arranged inside the first shift plate  553 . The link member  556  is configured to accommodate a shaft part  553   a  (refer to  FIG. 14B ) of the first shift plate  553  by a hole formed at a rear end portion thereof and to be thereby rotatably supported by the first shift plate  553 . A front end portion of the link member  556  is fixed to the shaft part  511   a  of the shift sensor  511 . The shaft part  511   a  rotates in conjunction with rotation of the link member  556 . 
     A central upper part of the first shift plate  553  is formed with an opening  553   b . The opening  553   b  is provided with a tongue piece part  553   c  formed in the width direction of the motorcycle. Also, a shaft part  553   d  passing through the opening  553   b  in the width direction of the motorcycle is arranged in the opening  553   b . The shaft part  553   d  is fixed to an upper surface of the tongue piece part  553   c  by welding or the like. The shaft part  553   d  is configured to be engaged with arm parts  557   a ,  557   b  of a torsion spring  557  (which will be described later). 
     An outer surface of the second shift plate  554  is provided with a boss  558  protruding towards the first shift plate  553 . The boss  558  has a cylindrical shape and is configured to accommodate therein the link shaft  551 . A torsion spring  557  is fixed to an outer periphery of the boss  558 . The torsion spring  557  has a pair of bowl parts  557   a ,  557   b . The bowl parts  557   a ,  557   b  are arranged to interpose the shaft part  553   d  therebetween. 
     The torsion spring  557  has a function of applying an urging force for returning the first shift plate  553  to its initial position (a position shown in  FIGS. 12 to 14B ). As described in detail later, after the first shift plate  553  rotates on the basis of an operation on the shift pedal  52 , the first shift plate  553  returns to its initial position by the urging force of the torsion spring  557 . 
     The shift detection unit  55  may be fixed to the sprocket cover  50  via the cover  512  after mounting the first shift plate  553  as a moveable side and the second shift plate  554  as a fixed side. The fixation to the sprocket cover  50  is made by the screws  552   a ,  552   b . As described above, the screws  552   a ,  552   b  are arranged at positions at which they are exposed from the first shift plate  553 , as seen from a side. Accordingly, when fixing the shift detection unit  55  to the sprocket cover  50 , the first shift plate  553  does not cause any interference. As the first shift plate  553  and the second shift plate  554  are assembled and are then fixed to the sprocket cover  50 , it is possible to improve the operation efficiency when mounting the shift detection unit  55 . 
     The shift detection mechanism  51  configured as described above is arranged at a position overlapping with a drive chain for transmitting the driving power to the rear wheel  11 . A relation between the shift detection mechanism  51  and the drive chain is described with reference to  FIG. 15 .  FIG. 15  is a side view of a surrounding of the shift detection mechanism  51  provided in the motorcycle  1  according to the illustrative embodiment. In  FIG. 15 , for convenience of explanations, a drive chain DC is pictorially illustrated with a dashed-two dotted line. 
     As shown in  FIG. 15 , the shift detection mechanism  51  is arranged at a position overlapping with the drive chain DC, as seen from a side. More specifically, the cover  512  of the shift detection mechanism  51  is arranged at a lower part outside the sprocket cover  50 , i.e., at a position overlapping with the drive chain DC. Accordingly, the sprocket cover  50  and the cover  512  of the shift detection mechanism  51  are arranged outside the drive chain DC. With a double structure of the sprocket cover  50  and the cover  512 , it is possible to achieve a sound deadening effect and to reduce a driving sound caused due to the rotation of the drive chain DC. 
     The cover  512  of the shift detection mechanism  51  is mounted to a side surface of the sprocket cover  50  and the shift sensor  511  is arranged outside the cover  512 . As the shift sensor  511  configured to detect the rotation of the shift detection unit  55  is arranged in a space different from the shift detection unit  55  with the cover  512  being interposed therebetween, it is possible to prevent a situation where the shift sensor  511  is to be damaged due to foreign matters involved by the drive chain DC. 
     Further, the shift detection unit  55  is arranged behind the clutch actuator  41  and the shift sensor  511  is arranged between the clutch actuator  41  and the shift detection unit  55  (refer to  FIGS. 12 and 15 ). Accordingly, it is possible to arrange the shift sensor  511  in the vicinity of the clutch actuator  41  and inside an outer end face of the clutch actuator  41 . Consequently, it is possible to protect the shift sensor  511  susceptible to a shock and the like by the clutch actuator  41 . 
     Subsequently, the configuration of the link mechanism  53  is described with reference to  FIGS. 12, 13, 16 and 17 .  FIGS. 16 and 17  are a plan view and a front view of a surrounding of the shift detection mechanism  51  and the link mechanism  53  provided in the motorcycle  1  according to the illustrative embodiment. In  FIGS. 16 and 17 , for convenience of explanations, the cover  512  of the shift detection mechanism  51  is omitted, and the vehicle body frame  2  (the body frame  23 ) is shown with dashed-two dotted lines. 
     As shown in  FIGS. 12 and 16 , the link mechanism  53  has a link rod  530  extending in the front and rear direction of the motorcycle and a link arm  531  coupled to the link rod  530 . A rear end portion of the link rod  530  is coupled to a tip end of a protruding piece  521  protruding downwards from a base end portion of the shift pedal  52 . A front end portion of the link rod  530  is coupled to a lower end portion of the link arm  531 . 
     The link rod  530  is coupled to the protruding piece  521  and the link arm  531  via pillow ball bearings  530   a ,  530   b , respectively (refer to  FIG. 17 ). As the link rod  530  is coupled via the pillow ball bearings  530   a ,  530   b , the link rod  530  is configured to be movable in the front and rear direction of the motorcycle while permitting rotations of the shift pedal  52  and the link arm  531 . 
     As shown in  FIG. 17 , the link arm  531  is arranged outside a center RRC of the link rod  530  in the width direction of the motorcycle. With this arrangement, the first shift plate  533  and the pillow ball bearings  530   a ,  530   b  can overlap with each other, as seen from a front side. Accordingly, it is possible to effectively utilize the space between the shift pedal  52  and the drive chain DC. 
     When the link rod  530  operates in the front and rear direction of the motorcycle, in response to an operation on the shift pedal  52 , the link arm  531  swings in an arrow I-J direction shown in  FIG. 13 , about the link shaft  551  serving as a swing support point. When the link shaft  551  is rotated in conjunction with the swing of the link arm  531 , the first shift plate  553  rotates in an arrow K-L direction shown in  FIG. 13 , about a center of the link shaft  551  serving as a rotation support point. The second shift plate  554  is fixed to the sprocket cover  50  and does not rotate. As the first shift plate  553  rotates, the link member  556  swings in the same direction. As the link member  556  swings, the shaft part  511   a  rotates. The shift sensor  511  detects the rotation of the shaft part  511   a  to detect a shift change instruction from the driver. 
     In the shift detection mechanism  51  configured to detect the shift change instruction, as described above, the link shaft  551  is configured as a separate shaft from the shaft part  511   a , which is a detection target by the shift sensor  511 . The link shaft  551  and the shaft part  511   a  extend in the width direction of the motorcycle at different positions deviated in the front and rear direction of the motorcycle. If the shaft part, which is a detection target, is arranged coaxially with the link shaft  551 , a size of the shift detection mechanism  51  in the width direction of the motorcycle increases. In the shift detection mechanism  51  according to the illustrative embodiment, as the link shaft  551  and the shaft part  511   a  are arranged as separate shafts, it is possible to shorten the dimension of the shift detection mechanism  51  in the width direction of the motorcycle. 
     Since the size of the shift detection mechanism  51  in the width direction of the motorcycle is reduced, it is possible to arrange the shift detection mechanism  51  in the vicinity of the vehicle body frame  2  or the drive chain DC, as seen from above. Accordingly, it is possible to arrange the shift pedal  52  in the vicinity of the vehicle body frame  2 . If the size of the shift detection mechanism  51  in the width direction of the motorcycle is large, it is necessary to arrange the shift detection mechanism  51  at an outer side in the width direction of the motorcycle and the shift pedal  52  is correspondingly arranged at an outer side. As a result, a straddling width of the motorcycle  1  by a driver increases. In contrast, in the shift detection mechanism  51  according to the illustrative embodiment, the size of the shift detection mechanism  51  in the width direction of the motorcycle is reduced, so that the straddling width can be reduced. Consequently, it is possible to provide the motorcycle  1  that a driver can easily drive. 
     In the motorcycle  1  according to the illustrative embodiment, the configuration of the link mechanism  53  has been described on the assumption that the AMT is mounted on the motorcycle. In general, regarding the motorcycle  1 , even when the vehicle type is the same, a motorcycle on which the AMT is not mounted is also manufactured around the same time. For this reason, as an illustrative embodiment, it is preferable to commonly use the configuration of the link mechanism  53  in the motorcycles of which specifications of the transmission devices are different. 
     The configuration of the link mechanism  53  is described in a case where the AMT is not mounted on the motorcycle  1  according to the illustrative embodiment.  FIGS. 18A and 18B  are side views of a surrounding of the link mechanism  53  provided in the motorcycle  1  according to the illustrative embodiment.  FIG. 18A  illustrates a configuration of the link mechanism  53  in a case where the ATM is mounted, and  FIG. 18B  illustrates a configuration of the link mechanism  53  in a case where the ATM is not mounted. In  FIG. 18B , for convenience of explanations, the common configurations to the illustrative embodiment are denoted with the same reference numerals and the descriptions thereof are omitted. 
     As shown in  FIG. 18A , the link rod  530  of the link mechanism  53  according to the illustrative embodiment extends with being slightly inclined upwards towards the motorcycle front-side. The front end portion of the link rod  530  is coupled to the link arm  531 . 
     On the other hand, as shown in  FIG. 18B , a motorcycle on which the AMT is not mounted is provided with a quick shift sensor  56 , for example, instead of the shift detection mechanism  51 . In this case, the front end portion of the link rod  530  is coupled to the quick shift sensor  56 . The quick shift sensor  56  constitutes a sensor for detecting an operation on the shift pedal  52  via the link rod  530 . The link rod  530  is coupled to the link shaft  551  below the quick shift sensor  56 , thereby directly rotating the link shaft  551 . 
     As shown in  FIG. 18B , even when the quick shift sensor  56  is provided, the link rod  530  of the link mechanism  53  extends with being slightly inclined upwards towards the motorcycle front-side. As shown in  FIGS. 18A and 18B , the inclined angle of the link rod  530  is set to be substantially the same. That is, in the link mechanism  53  according to the illustrative embodiment, it is possible to set the extending direction of the link rod  530  to be substantially the same, irrespective of whether the AMT is mounted. Accordingly, it is possible to commonly use the link mechanism  53  in the same vehicle type of which the specifications of the transmission devices are different simply by changing the constitutional member to be coupled to the link rod  530 . Consequently, it is not necessary to prepare the link mechanisms  53  having different configurations for each of the specifications, so that it is possible to save the manufacturing cost. 
     The present invention is not limited to the illustrative embodiment and can be diversely changed and implemented. In the illustrative embodiment, the sizes, shapes and the like shown in the accompanying drawings are not limited thereto and can be appropriately changed within the scope in which the effects of the present invention are to be achieved. In addition, the illustrative embodiment can be appropriately changed and implemented without departing from the purpose of the present invention. 
     For example, in the illustrative embodiment, the clutch actuator  41  and the shift actuator  42  are arranged inside the outer end face of the mug cover  35 . However, the arrangement of the actuators is not limited thereto and can be appropriately changed. For example, the clutch actuator  41  and the shift actuator  42  may be arranged inside a line connecting the outer end face of the mug cover  35  and an outer end face of the vehicle body frame  2 . Even in this case, it is possible to avoid a situation where the clutch actuator  41  and the shift actuator  42  come in contact with a road surface or the like when the motorcycle  1  is turned over, as well as the illustrative embodiment. 
     Also, in the illustrative embodiment, the AMT has been exemplified as the transmission device. However, the transmission device to be mounted on the motorcycle is not limited thereto and can be appropriately changed. For example, the present invention can also be applied to a motorcycle having a DCT as the transmission device, on the assumption that the clutch actuator and the shift actuator are provided. 
     As described above, the present invention achieves the effect of shortening the dimension of the shift detection mechanism in the width direction of the vehicle. In particular, the present invention is useful for any motorcycle having the shift actuator.