Automated transmission controller and vehicle including the automated transmission controller

A transmission controller can be configured to initially operate a shift actuator to start a gear change process. Additionally, the controller can be configured to perform a process for reducing engine driving force, such as, but without limitation, an ignition delaying process, a fuel injection quantity reducing process, an air quantity reducing process, or another process simultaneously with the initiation of the gear change. After an elapse of a predetermined time from initiation of gear change, a clutch actuator can be operated to start disconnection of a clutch.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of Japanese Patent Application No. 2006-114702, which was filed on Apr. 18, 2006 and which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTIONS

1. Field of the Inventions

The present inventions relate to an automated transmission controller which can automatically execute shift changes, and to a vehicle including the automated transmission controller.

2. Description of the Related Art

Recently, vehicles with electronically actuated manual transmission have become commercially available. These transmissions are largely the same as any conventional manual transmission, except electronic actuators have been added to allow the otherwise manual transmission to be operated electronically.

The actuators are used to automate certain operations so that the system can automate a series of start, stop and shift change operations (clutch disengagement, gear change, and clutch engagement) based on the rider's intention or the state of the vehicle. For example, Japanese Patent Documents JP-A-2001-146930 and JP-A-2001-173685 disclose transmission controllers which control the operation of the actuators (clutch actuator and shift actuator) such that processes for disconnection of the friction clutch, gear change of the transmission, and half-clutch control over the friction clutch (connecting operation) can be performed in this order at the time of shift change.

SUMMARY OF THE INVENTIONS

An aspect of at least one of the embodiments disclosed herein includes the realization, the shift change operation performed by the above transmission controller requires the friction clutch to be disengaged for an unnecessarily long period of time which thereby unnecessarily causes following problems. In shift-up operations, and in particular, after significant acceleration has been provided immediately before the shift-up operation, the unnecessarily long disengagement of the clutch can make the rider feel uncomfortable. Moreover, during higher-speed operation, wind resistance is larger, and thus, if the clutch the disengaged for an unnecessarily long period of time, the vehicle slows excessively. When these problems occur, the riding experience adversely affected.

Thus, in accordance with an embodiment, an automated transmission controller can comprise a friction clutch and a transmission having a plurality of first gears on which engaging projections are formed and a plurality of second gears on which engaging concaves are formed, the engaging concaves configured to be engaged with the engaging projections, the transmission being configured to effect gear changes through the engagement of the engaging projections of the first gears with the engaging concaves of the second gears. The controller can also include a clutch actuator configured to connecting and disconnecting the friction clutch and a shift actuator configured to cause at least one of the first and second gear to move so as to engage the engaging projections with the engaging concaves and thereby executing a gear change of the transmission. A control unit can be configured to control operations of the clutch actuator and the shift actuator. Additionally, the control unit can be configured to initially operate the shift actuator to start a gear change of the transmission and then to operate the clutch actuator to start disconnection of the friction clutch.

Such a transmission controller can provide enhanced transmission performance. For example, where the disconnection of the friction clutch is started after initiation of gear change, the time during which the clutch is disengaged can be shorter than that resulting from the shift change operations in the above identified related arts. As a result, the period of non-acceleration resulting during the gear change, which is even more significant during higher speed operation generating higher wind resistance, can be reduced thus providing the rider with a more pleasing riding experience.

In accordance with another embodiment, an automated transmission controller can comprise a friction clutch, a transmission having a plurality of gears defining a plurality of gear ratios, a clutch actuator configured to connecting and disconnecting the friction clutch, a shift actuator configured to cause the transmission to shift between the plurality of gear ratios. The controller can also comprise means for initially operating the shift actuator to start a gear change of the transmission and then to operate the clutch actuator to start disconnection of the friction clutch based on a single gear shift command from a user of the transmission controller.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1is a side view of a motorcycle1having a transmission arranged and configured in accordance with an embodiment. The transmission is disclosed in the context of a motorcycle because it has particular utility in this context. However, the transmission can be used in other contexts, such as, for example, but without limitation, scooters, automobiles, as well as other vehicles.

With continued reference toFIG. 1, the motorcycle10includes a vehicle body frame11defining a framework, and a seat16on which a rider sits. The seat16is configured such that the rider straddles the seat, astride the vehicle body frame11, during operation.

The shape of the motorcycle10is not limited to that shown inFIG. 1, nor are the maximum speed, displacement volume, size, and other conditions of the vehicle limited thereto. Additionally, the inventions disclosed herein are not limited to a so-called motorcycle-type two-wheel vehicle which includes a fuel tank before the seat, but are applicable to other types of two-wheel vehicles. Moreover, the inventions disclosed herein are not limited to two-wheel vehicles, but may be used with other types of saddle-type vehicle. Furthermore, the inventions disclosed herein are not limited to saddle-type vehicles, but can be used with other types of vehicles such as four-wheel buggy for two riders.

In the following description, the front-and-rear direction and the left-and-right direction are defined as viewed by the rider sitting on the seat16.

With continued reference toFIG. 1, the vehicle body frame11can have a steering head pipe12, a main frame13extending diagonally downward to the rear from the steering head pipe12, left and right seat rails14extending diagonally upward to the rear from the immediate position of the main frame13, and left and right seat pillar tubes15connected with the rear end of the main frame13and the intermediate positions of the seat rails14.

A front wheel19can be supported by the steering head pipe12via a front fork18. A fuel tank20and the seat16can be supported on the seat rails14. The seat16can extend from above the fuel tank20toward the rear ends of the seat rails14. The fuel tank20can be disposed above the front half parts of the seat rails14.

A pair of left and right rear arm brackets24can be provided at the rear end of the main frame13. In this embodiment, the rear arm brackets24and other components provided on the main frame13can be considered as forming a part of the vehicle body frame11. However, other configurations can also be used.

The rear arm brackets24project downwardly from the rear end of the main frame13. Pivot shafts38can be equipped on the rear arm brackets24, and the front ends of rear arms25can be supported by the pivot shafts38such that the rear arms25can freely swing. A rear wheel26can be supported by the rear ends of the rear arms25.

An engine unit28for driving the rear wheel26can be supported by the vehicle body frame11. A crank case35can be supported by the main frame13in such a manner as to be suspended therefrom. In some embodiments, a gasoline engine (not shown) can be provided in the engine unit28. However, the engine included in the engine unit28is not limited to an internal combustion engine such as a gasoline engine, but may be an electric motor, a hybrid gasoline, electric system, or other types of propulsion systems.

The motorcycle10can also include a front cowl33and left and right leg shields34. The leg shields34can cover components covering the front parts of the rider's legs. However, other configurations can also be used.

Though not shown inFIG. 1, a brake pedal can be equipped in the lower right area of the motorcycle10. The brake pedal can be a component for braking the rear wheel26. The front wheel19can be braked by operating a brake lever (not shown) provided in the vicinity of a right grip41R (seeFIG. 2) of a handlebar41.

A clutch lever104can be disposed in the vicinity of a left grip41L of the handlebar41. In some such embodiments, engagement and disengagement of the clutch can be effected also by operating the clutch lever104as well as automatically, described in greater detail below.

FIG. 2illustrates a structure of a driving system that can be used with the motorcycle shown inFIG. 1. In some embodiments, the right grip41R of the handlebar41(see alsoFIG. 1) comprises a rotatable accelerator grip. A throttle input sensor42can be attached to the accelerator grip.

The throttle input sensor42can be configured to detect acceleration input (throttle opening input) given by the rider, which can also be referred to as a torque request or power output request. A shift switch43can be disposed on the left grip41L of the handlebar41, although other locations can also be used.

With continued reference toFIG. 2, the shift switch43can include a shift-up switch43aand a shift-down switch43b, thereby giving the operator a device for requesting increases and decreases in the gear position. For example, in some embodiments, the motorcycle can be shifted in the range between the neutral position and the maximum gear position (e.g., 6 gear positions in an exemplary but non-limiting embodiment) by manual operation. An indicator45can be configured to display the current shift position or the like can be provided at the center of the handlebar41.

Throttle valves46can be attached to throttles bodies47, which can be considered as forming an air intake passages. A throttle drive actuator49can be attached to one end (the right end in the illustrated embodiment) of a valve shaft48to which the throttle valves46can be rotatably connected. A throttle opening sensor50can be attached to the other end (the left end in the illustrated embodiment) thereof. The throttle drive actuator49and the throttle opening sensor50attached to the valve stem48can be considered as forming a DBW (drive by wire)51system. However, other configurations can also be used and considered as forming a drive by wire system. The DBW51can be configured to open and closes the throttles47through the throttle drive actuator49based on the detection results from the throttle opening sensor50, as well as other calculations and/or determinations, described in greater detail below.

An engine revolution sensor53can be configured to detect rotation of the crankshaft52. In the illustrated embodiment, the engine revolution sensor53is disposed on the right side of a crankshaft52. However, other positions can also be used.

The crankshaft52can be connected to a main shaft55via a wet multi-disc-type clutch54, although other types of clutches can also be used. The clutch54can have a clutch housing54aand a clutch boss54b. A plurality of friction plates54ccan be attached to the clutch housing54a, and a plurality of clutch plates54dcan be attached to the clutch boss54b. Each of the clutch plates54dcan be interposed between the adjoining friction plates54c,54c. As noted above, other types of clutches can also be used, including, but without limitation, a dry clutch or a single-plate-type clutch.

The main shaft55can have multiple-position (six positions inFIG. 2) transmission gears57and a main shaft revolution sensor56. Each of the transmission gears57attached to the main shaft55can engage with a corresponding transmission gears59attached onto a drive shaft58disposed parallel with the main shaft55. InFIG. 2, the transmission gears57and the transmission gears59are separated so as to simplify the explanation.

The transmission gears57,59are attached such that either or both of the gears57,59, other than the selected gears, are attached to the main shaft55or drive shaft58during idling of the engine. Thus, driving force can be transmitted from the main shaft55to the drive shaft58only through a selected pair of the transmission gears. The condition in which the pair of the transmission gears57and59engage with each other and transmit driving force from the main shaft55to the drive shaft58is referred to as “gear-in” condition or the “gear position”.

The operation for selecting or meshing the desired pair of transmission gears57and transmission gears59and changing between such pairs can be performed with a shift cam79. The shift cam79can have a plurality of cam grooves60(three grooves are illustrated inFIG. 2, although other numbers of grooves can also be used), and shift forks61are attached to the respective cam grooves60.

The respective shift forks61engage with the predetermined transmission gears57and59of the main shaft55and drive shaft58. When the shift cam79rotates, the shift forks61move along the cam grooves60in the axial direction and accordingly the predetermined transmission gears57,59engaging with the splines of the main shaft55and drive shaft58move in the axial direction. Then, the transmission gears57,59having moved in the axial direction engage with another pair of the transmission gears57,59attached to the main shaft55and drive shaft58in idling condition to complete the gear change process. The transmission gears57,59and the shift cam79can be considered as forming a transmission80, although other configurations can also be used to form the transmission80.

The transmission80can be a dog-clutch-type transmission. As illustrated inFIG. 3, each of the transmission gears57of the transmission80has a first gear57ahaving engaging projections57con an axial end surface thereof, and a second gear57bhaving engaging concaves57eon its axial end surface opposed to the engaging projections57c. The transmission80can include a plurality of first gears57aand second gears57b. Also, the transmission80can include a plurality of first gears having engaging projections and a plurality of second gears having engaging concaves as the transmission gears59. Since these structures of the transmission gears59are similar to those of the first gears57aand second gears57bshown inFIG. 3, explanation of the transmission gears59is not repeated herein.

Each of the first gears57ahas the three engaging projections57cdisposed at equal intervals on the outer edge of its axial end surface in the circumferential direction. Each of the second gears57bhas the six engaging concaves57ealso disposed at equal intervals in the circumferential direction. However, other numbers of projections57cand concaves57ecan also be used.

An insertion hole57gthrough which the main shaft55and the drive shaft58are inserted is formed at the axial center of the first gear57a. A plurality of grooves57dare provided along the circumference of the insertion hole57g. The first gear57aengages with the splines of the main shaft55and the drive shaft58. The second gear57bhas an insertion hole57hthrough which the main shaft55and the drive shaft58are inserted, but the insertion hole57hdoes not have grooves around the hole. Thus, the second gear57bcan be attached to the main shaft55and the drive shaft58in idling condition.

When the shift cam79(FIG. 2) rotates, the shift forks61move along the cam grooves60and accordingly, the first gear57amoves along the splines of the main shaft55and the drive shaft58in the axial direction. Then, the engaging projections57cof the first gear57acome to engagement with the engaging concaves57eof the second gear57b, thereby changing the combination of the transmission gears57,59for transmitting the driving force from the main shaft55to the drive shaft58and completing the gear change process.

Additionally, when the shift cam79(FIG. 2) rotates, the first gear57amoves in the axial direction. At this step, the engaging projections57cof the first gear57ado not engage with the engaging concaves57eof the second gear57bbut contact an axial end face57fof the second gear57bin dog-contact condition in some cases. Under the dog-contact condition, the first gear57aand second gear57bdo not engage but contact with each other, failing to securely attain gear change.

As illustrated inFIG. 2, the clutch54and the transmission80can be operated by a clutch actuator63and a shift actuator65, respectively. The clutch actuator63can be connected with the clutch54via a hydraulic transmission mechanism64, a rod71, a lever72, a pinion73, and a rack74.

The hydraulic transmission mechanism64can also include a hydraulic cylinder64a, an oil tank (not shown), a piston (not shown) and other components. The hydraulic transmission mechanism64can also be configured to generate hydraulic pressure by the operation of the clutch actuator63and transmits the hydraulic pressure to the rod71. The rod71thus reciprocates in the direction indicated by an arrow A by the operation of the clutch actuator63, thereby rotating the lever72in the direction indicated by an arrow B. As a result, the clutch54can be connected or disconnected in accordance with the movement direction of the rack74. While an electric motor can be used as the clutch actuator63in some embodiments, other devices such as a solenoid and an electromagnetic valve, or other actuators can also be used.

An automated transmission controller can comprise the transmission80, the shift actuator65, a deceleration mechanism66, a rod75, a link mechanism76, an ECU100(FIG. 4) for controlling the operations of the clutch actuator63and shift actuator65. However, other configurations can also be used. An automated clutch device77can comprise the clutch54, the clutch actuator63, the hydraulic transmission mechanism64, the rod71, the lever72, the pinion73, and the rack74. However, other configurations can also be used.

The shift actuator65can be connected with the shift cam79via the deceleration mechanism66, a spring85, the rod75, and the link mechanism76. The deceleration mechanism66can have a plurality of reduction gears (not shown).

The spring85can be configured to urge the rod75in accordance with the operation of the shift actuator65. The spring85can be any type of spring, any type of elastic or resilient member such as an elastic resin, or any type of device that can generate a biasing force.

The spring85can be not required to urge the rod75as in this embodiment as long as the spring85urges at least a part of the power transmission mechanism (deceleration mechanism66, the rod75and the link mechanism76) provided between the shift actuator65and the transmission80. For example, the spring85may urge the deceleration mechanism66or the link mechanism76. The elastic member according to the invention is not limited to a spring, but may be other types of elastic member such as elastic resin.

At the time of gear change, the rod75reciprocates in the direction indicated by an arrow C by the operation of the shift actuator65, and the shift cam79rotates through a predetermined angle via the link mechanism76. Then, the shift forks61move along the cam grooves60by a predetermined amount in the axial direction. As a result, a pair of the transmission gears57,59are fixed to the main shaft55and the drive shaft58, respectively, and thus driving force can be transmitted from the main shaft55to the drive shaft58. While an electric motor can be used as the shift actuator65in some embodiments, other devices such as solenoid, an electromagnetic valve, or other devices can also be used.

The hydraulic transmission mechanism64connected with the clutch actuator63can include a clutch position sensor68for detecting a position of the clutch (e.g., a distance between the friction plates54cand the clutch plates54d) based on the detection of the stroke position of the piston. While the clutch position can be detected by the clutch position sensor68which detects the stroke position of the piston in some embodiments, the clutch position may be detected based on the detection of the position of the transmission mechanism provided between the clutch actuator63and the clutch54.

For example, the clutch position can be detected based on the detection of the position of the rod71or the rack74. The detection of the clutch position is not limited to indirect detection based on the detected stroke position of the piston as in the illustrated embodiment, but can be through direct measurement of the distance between the friction plates54cand the clutch plates54dusing a sensor (not shown).

The drive shaft58can have a vehicle speed sensor69. The shift cam79can have a gear position sensor70configured to detect the gear position (e.g., a rotational position of the shift cam79).

The ECU100(engine control unit) can be configured to control the operations of the clutch actuator63and the shift actuator65in accordance with the operation of the shift-up switch43aor the shift-down switch43bto execute shift change. For example, the ECU100can be configured to execute a sequential processes involving starting gear change of the transmission gears57,59by the shift actuator65, disconnecting the clutch54by the clutch actuator63after elapse of a predetermined time from the start of gear change, and connecting the clutch54by the clutch actuator63, in this order, under a predetermined program or a map at the time of running of the vehicle. However, the ECU100can be configured to execute other gear changing processes as well as other operations for the operation of the motorcycle10.

FIG. 4is a block diagram illustrating an exemplary structure of a gear change controller that can be provided on the motorcycle10for performing gear changes. A drive system group110can be connected with a main microcomputer90contained in the ECU100via a drive circuit93.

The ECU100can be considered as forming a control unit or a gear change controller. However, the gear change controller disclosed herein can also be constructed in other ways. For example, the gear change controller can be in the form of one or a plurality of hard-wired feedback control circuits. Alternatively, the gear change controller can be constructed of a dedicated processor and a memory for storing a computer program configured to perform the control routine ofFIG. 7. Additionally, the gear change controller can be constructed of a general purpose computer having a general purpose processor and the memory for storing the computer program for performing the routine ofFIG. 7. Preferably, however, the gear change controller is incorporated into the ECU100, in any of the above-mentioned forms.

As shown inFIG. 5, the drive system group110can include the throttle drive actuator49, the indicator45, the clutch actuator63, and the shift actuator65(see alsoFIG. 2). The drive circuit93can be configured to supply appropriate electric current to the respective devices of the drive system group110from a battery97in response to drive signals sent from the main microcomputer90. A sensor and switch group120can be connected with the main microcomputer90.

As shown inFIG. 6, the sensor and switch group can be constituted by the throttle input sensor42, the shift switch43, the throttle opening sensor50, the engine revolution sensor53, the main shaft revolution sensor56, the clutch position sensor68, the vehicle speed sensor69, and the gear position sensor70(see alsoFIG. 2), as well as other sensors. The detection results from the respective sensors can be input to the main microcomputer90, and then the main microcomputer90can supply drive signals to the respective devices constituting the drive system group110based on the detection results obtained from the respective sensors to control the operations of these devices.

The main microcomputer90can have a ROM91and a RAM92. The ROM91can be used to store a clutch actuator control program91aand a shift actuator control program91b. The clutch actuator control program91acan be a program for controlling the operation of the clutch actuator63. The shift actuator control program91bcan be program for controlling the operation of the shift actuator65. The ROM91can be constructed in a manner that makes it is impossible for a user to delete these programs stored in the ROM91, or to write new programs or the like to the ROM91. However, other types of memory can also be used.

For executing the clutch actuator control program91aor the shift actuator control program91b, either of these programs can be loaded into the RAM92and read by the main microcomputer90. Then, the main microcomputer90controls the operation of the clutch actuator63or the shift actuator65under the program in the RAM92.

A power source circuit98connected with the battery97can have a main switch96which can be turned on or off in accordance with the operation of a key switch (not shown). When the main switch96is turned on, the power source circuit98converts voltage of the battery97into driving voltage for the main microcomputer90and supplies the converted voltage to the main microcomputer90.

FIG. 7is a flowchart illustrating a shift change control process that can be used during operation of a vehicle such as the motorcycle10. When a shift change is requested by a rider of the motorcycle, e.g., when a rider operates the shift-up switch43aor the shift-down switch43b, the shift change control process ofFIG. 7can be used to carry out the rider's desire for a gear change. The procedures shown inFIG. 7can be carried out for all gear changes.

In some embodiments, the shift change control process ofFIG. 7can be used only when the rider of the motorcycle10activates one of the switches43a,43b. Additionally, in some embodiments, the can be shift change control process ofFIG. 7can be performed automatically executed under predetermined conditions. For example, an up-shift, using the routine ofFIG. 7, can be performed when the speed of the engine rises to a predetermined value without requiring the rider to active the shift-up switch43a. On the other hand, a down-shift, using the routine ofFIG. 7, can be performed when the speed of the engine falls to a predetermined level, without requiring the rider to active the shift-up switch43b. Thus, the shift change control process may be automatically performed in response to so-called auto-shift commands.

With reference to the control routine illustrated inFIG. 7, initially, the ECU100starts gear change in step S100. In this step, the ECU100can supply a drive signal to the shift actuator65so that the shift actuator65initiates a gear change of the transmission gears57,59. With initiation of this step, the shift cam79starts rotating.

After step S100is completed, a process for reducing engine driving force (driving force reduction process) can be carried out in step S110. In some embodiments, at least one of the three procedures described below can be performed in the driving force reduction process. While the driving force reduction process is conducted simultaneously with the initiation of gear change in step S100in this embodiment, the driving force reduction process may be performed before starting gear change or after starting gear change according to the invention.

One of the optional driving force reduction processes can comprise delaying ignition. For this optional delaying ignition procedure, the ECU100can transmit a control signal to an ignition or spark plug control circuit (not shown) and can change the ignition timing of an spark plug is retarded (i.e., delayed) which can cause a reduction in power without interrupting the operation of the engine. Additionally, such an optional procedure can include delaying the opening timing of an air intake valve (not shown) until after the top dead center.

Another optional driving force reduction process can comprise reducing the fuel injection quantity. For reducing the injection quantity, for example, the ECU100can transmit a control signal to an injection valve control circuit (not shown) to reduce the fuel injection quantity supplied through a fuel injection valve. This can cause air-fuel mixtures delivered to the combustion chambers of the engine to be lean, thereby reducing the power output of the combustion resulting from the lean air/fuel mixtures, and thus reducing the power output of the engine.

Still another optional driving force reduction process can comprise reducing the air quantity. For reducing the air quantity, the ECU100can transmit a control signal to the electronically controlled throttle valves46(seeFIG. 2) to control the opening of the throttle valves46and reduce the quantity of air passing through the air intake passage, and thereby reducing the power output of the engine.

Procedures for reducing driving force other than the above three procedures can also be performed. As noted above, one or a combination of any of the above-noted or other known procedures for reducing the driving force can be performed.

After the process in step S110is completed, it can be determined whether a predetermined time has elapsed in step S120. In this step, ECU100judges whether the predetermined time has elapsed after gear change is initiated according to the process in step S100. When it is determined that the predetermined time has not elapsed yet, the routine returns to step S120and waits until the predetermined time elapses.

When it is determined that the predetermined time has elapsed after the initiation of gear change in step S120, disengagement of the clutch can be started in step S130. As such, the disengagement of the clutch54is delayed for a predetermined time after the beginning of the gear change process of Step S100. In step S120, the ECU100can supply a driving signal to the clutch actuator63to cause the clutch actuator63to disconnect the clutch54. When this step is conducted, the clutch54can be brought into disengagement at a fixed speed until the clutch54comes to a predetermined clutch position.

After the process in step S130is completed, it can be determined whether the clutch is in the disengagement condition in step S140. In this step, the ECU100can judge whether the position of the clutch54is at the disengagement position based on the detection result from the clutch position sensor68(FIG. 2). When it is determined that the clutch54is not in the disengagement condition, the routine returns to step S140and waits until the clutch54reaches the disengagement condition.

When it is determined that the clutch54is in the disengagement condition in the step S140, a process for maintaining the clutch position can be performed in step S150. In this process, the ECU100executes a process for maintaining the clutch position determined as the position of disengagement condition in step S140. By this process, the clutch54can be maintained under the disengagement condition.

After the process in step S150is completed, it can be determined whether gear has been completed in step S160. In this step, the ECU100judges whether gear change has been finished based on the detection result from the gear position sensor70. When it is determined that gear change has not been completed, the routine returns to step S160and waits until gear change is completed.

When it is determined that gear change has been completed in step S160, the clutch54can be connected in step S170. In this step, the ECU100can supply a drive signal to the clutch actuator63to cause the clutch actuator63to connect the clutch54. In step S170, half-clutch control under which the clutch54can be gradually connected can be performed from the time when the connection of the clutch54is started until the time when the clutch54reaches the predetermined clutch position. After execution of the process in step S170, the shift change control process during running of the vehicle is completed.

FIGS. 8(a) and8(b) show the clutch position and gear position with elapse of time when the shift change control process during running of the vehicle shown inFIG. 7is executed.FIGS. 9(a) and9(b) show the clutch position and gear position with elapse of time at the same of shift change during running of a motorcycle according to the related art.

FIG. 9(a) shows the clutch position from the beginning to the end of shift change.FIG. 9(b) shows the gear position with elapse of time from the beginning to the end of shift change. As shown inFIG. 9(a), conventionally, gear change is started (time t22) after elapse of a predetermined time from the initiation of disengagement of the clutch54(time t21). After the clutch54is brought to the disengagement condition, this condition is maintained at this clutch position and completion of gear change is detected (time t23). Then, after half-clutch control (time t24), the clutch54is connected. In the related art, therefore, disengagement of the clutch54is initially started after initiation of shift change, and then gear change is started after elapse of the predetermined time from the initiation of disengagement.

On the other hand, according to the motorcycle10in some embodiments shown inFIGS. 8(a) and8(b), gear change is initially started after initiation of shift change (time t11). In addition, the driving force reduction process (FIG. 7, step S110) can be started simultaneously with the initiation of gear change. The driving force reduction process can reduce driving force transmitted to the main shaft55. Thus, the engaging first gear57aand second gear57bcan be easily separated (dog-separated) at a predetermined clutch position (half-clutch position) during the disengagement period of the clutch54which follows the driving force reduction process. Thus, in the step where the driving force transmitted to the main shaft55is gradually reduced by the disengagement of the clutch54, the driving force reduction process can be a supplemental process for reducing the driving force for the main shaft55.

After elapse of a predetermined time from the initiation of gear change (time t11), disconnection of the clutch54starts (time t12). When the gear position in the dog-separation condition at the lower position comes to a possible dog-contact condition at the higher position after the initiation of disengagement of the clutch54(time t13) or slightly after the possible dog-contact condition, the clutch54is brought into disengagement condition. Thus, at the time of engagement between the fist gear57aand second gear57b, driving force transmitted to the main shaft55can be reduced to almost zero. As a result, the gear-in condition can be smoothly achieved. Then, the disengagement condition of the clutch54is maintained and completion of gear change is detected similarly to the case ofFIGS. 9(a) and9(b) (time t14). After half-clutch control, the clutch54is connected (time t15).

In some embodiments, as discussed with reference toFIGS. 8(a) and8(b) andFIGS. 9(a) and9(b), the shift actuator65is initially operated to start gear change when the shift change requiring operation is conducted during running of the vehicle. After elapse of the predetermined time from the initiation of gear change, the clutch actuator63is operated to start disconnection of the clutch54. Thus, the disengagement period of the clutch54(see t12through t15inFIGS. 8(a) and8(b)) is shorter than that according to the related art (t21through t24inFIGS. 9(a) and9(b)). Since the disengagement period of the clutch54is short, the period of non-acceleration even at the time of operation the accelerator and the period of deceleration due to running resistance can be reduced. Accordingly, riding feeling given to the rider can be enhanced.

According to the motorcycle10in some embodiments, therefore, gear change is initially started when shift change is required during running of the vehicle, and the disconnection of the clutch54is started after elapse of the predetermined time from the initiation of gear change. Thus, the disengagement period of the clutch54can be shortened. Accordingly, the period of non-acceleration even at the time of operation of the accelerator and the period of deceleration due to running resistance can be reduced, and thus riding feeling given to the rider can be enhanced.

In some embodiments, completion of gear change of the transmission80is detected by the gear position sensor70after the start of disconnection of the clutch54, and half-control over the clutch54is started based on this detection. Thus, half-clutch control can be initiated after gear change is securely completed.

In some embodiments, the spring85for urging the rod75in accordance with the operation of the shift actuator65is provided. Thus, when the dog-separation is carried out with the clutch54engaging, large reaction force given from the first gears57and59can be eliminated. Additionally, force applied to the rod75can be maintained at a constant level.

In some embodiments, the driving force reduction process (at least one of the procedures for delaying ignition, reducing the injection quantity, and reducing the air quantity) is also performed at the time of shift change. Thus, driving force transmitted to the main shaft55through the clutch54can be reduced. Accordingly, dog-separation can be easily carried out at the half-clutch position during the disengagement period of the clutch54.

In some embodiments, it is determined whether gear change has been completed after the clutch54is brought into disengagement condition. When it is determined that gear change has been completed, the process goes to the clutch connecting step. In this case, the clutch54is temporarily in the disengagement condition when gear change is completed at any time during the disengagement period of the clutch54, and thereafter the clutch54is connected. However, the clutch54may be promptly connected when gear change is completed by monitoring the gear position simultaneously with the initiation of gear change.

For example,FIG. 10shows the clutch position with elapse of time during shift change in a motorcycle in a modified example. In the motorcycle operation shown inFIG. 10in this modified example, the gear position sensor70starts monitoring the gear position simultaneously with the start of operation of the shift actuator65. When completion of gear change is detected during the disengagement period of the clutch54, half-clutch control over the clutch54is initiated.

In the modified example shown inFIG. 10, therefore, the gear position is monitored from the initiation of gear change, and half-clutch control is promptly started when completion of gear change is detected. As a result, time required for disengagement of the clutch54can be reduced to the minimum in accordance with the respective running conditions such as accelerating and climbing a slope. Accordingly, time required for shift change can be shortened.