Device and method for controlling transmission mechanism, and method for controlling motor vehicle

In a motor vehicle having a clutch and a transmission, an additional shift command is accepted during an already ongoing shift operation, thereby providing control that makes possible a responsive shift operation. When a shift command is issued during an ongoing shift operation and engagement operation of the clutch, the disengagement operation of the clutch and the dog insert operation of the transmission are conducted according a second schedule so that the dog insert operation of the transmission is conducted during the disengagement operation of the clutch, and a second shift operation including the re-engagement of the clutch is conducted.

PRIORITY INFORMATION

This patent application is based on and claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2008-132191, filed on May 20, 2008, which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a device and a method for controlling a transmission mechanism of a motor vehicle, and to a motor vehicle. In particular, the present invention relates to control exercised when engaging a clutch in a motor vehicle having a clutch and a dog clutch transmission.

BACKGROUND

A motor vehicle having a dog clutch transmission in which a clutch and a transmission are actuated by actuators such as motors has already become practically available. Such a motor vehicle is primarily characterized by automatically performing a series of shift operations including disengaging of the clutch, shifting of gears, and re-engaging of the clutch, when a rider inputs a shift command.

Japanese Unexamined Patent Application Publication No. 2006-170229 (hereinafter “Japanese '229 application”) discloses a motor vehicle with a dog clutch transmission, wherein a clutch and a transmission are actuated by actuators such as motors. When a shift command is input while control in accordance with a running state program is being exercised in the motor vehicle disclosed in the Japanese '229 application, the following steps are executed: activating the clutch actuator so as to disengage the clutch once; activating the shift actuator so as to upshift the transmission; switching to upshift control, in which the clutch actuator is activated so as to re-engage the clutch; and then switching to control in accordance with a running state program when the upshift control is finished.

In the motor vehicle disclosed in the Japanese '229 application, after the upshift control is finished and before the control is switched to control performed in accordance with a running state program, a rider may input an additional shift command at that timing, feeling that the shift operation has already finished. When the shift command is not carried out in this case, the rider may feel uncomfortable and feel that the motorcycle is unresponsive.

The present invention has been achieved against such a background. An object of the present invention is to provide control that makes possible a shifting operation having a good response by accepting an additional shift command during a shift operation of a motorcycle having a clutch and a dog clutch transmission.

SUMMARY

In order to achieve the object, in one embodiment of a device for controlling a transmission mechanism for a motor vehicle according to the present invention, the transmission mechanism includes a transmission having a clutch, gears each having a dog, and gears each having a recess into which the dog is inserted, the clutch and the gears being actuated by respective actuators, wherein a shift operation is conducted by conducting a dog insert operation in which a specified one of the dogs is inserted into a specified one of the recesses, and the device includes a shift command receiving unit for receiving a shift command; a shift control unit for conducting disengagement and engagement operations of the clutch and the shift operation including the dog insert operation of the transmission in accordance with the shift command; and a shift command timing determining unit for determining timing at which the shift command was issued, wherein, when the shift command timing determining unit determines that the shift command was issued at a timing at which the shift operation was not being conducted, the shift control unit conducts a first shift operation in which the disengagement operation of the clutch and the dog insert operation of the transmission are conducted in accordance with a first schedule and then the engagement operation of the clutch is conducted, and wherein, when the shift command timing determining unit determines that the shift command was issued at a timing at which the shift operation and the engagement operation of the clutch were being conducted, the shift control unit interrupts the engagement operation of the clutch and conducts a second shift operation in which the disengagement operation of the clutch and the dog insert operation of the transmission are conducted in accordance with a second schedule that is different from the first schedule and then the engagement operation of the clutch is conducted.

In one method for controlling a transmission mechanism of a motor vehicle according to the present invention, the transmission mechanism includes a transmission having a clutch, gears each having a dog, and gears each having a recess into which the dog is inserted, the clutch and the gears being actuated by respective actuators, wherein a shift operation is conducted by inserting a specified one of the dogs into a specified one of the recesses, and the method includes a shift command receiving step for receiving a shift command; a shift control step for conducting disengagement and engagement operations of the clutch and the shift operation including the dog insert operation of the transmission in accordance with the shift command; and a shift command timing determining step for determining timing at which the shift command was issued, wherein, when it is determined at the shift command timing determining step that the shift command was issued at a timing at which the shift operation was not being conducted, a first shift operation in which the disengagement operation of the clutch and the dog insert operation of the transmission are conducted in accordance with a first schedule and then the engagement operation of the clutch is conducted in the shift control step, and wherein, when it is determined at the shift command timing determining step that the shift command was issued at a timing at which the shift operation and the engagement operation of the clutch were being conducted, the engagement operation of the clutch is interrupted and a second shift operation in which the disengagement operation of the clutch and the dog insert operation of the transmission are conducted in accordance with a second schedule that is different from the first schedule and then the engagement operation of the clutch is conducted in the shift control step.

In a further method for controlling a motor vehicle according to the present invention, the motor vehicle includes a transmission mechanism including a transmission having a clutch, gears each having a dog, and gears each having a recess into which the dog is inserted, the clutch and the gears being actuated by respective actuators, wherein a shift operation is conducted by inserting a specified one of the dogs into a specified one of the recesses, and the method includes a shift command receiving step for receiving a shift command; a shift control step for conducting disengagement and engagement operations of the clutch and the shift operation including the dog insert operation of the transmission in accordance with the shift command; and a shift command timing determining step for determining timing at which the shift command was issued, wherein, when it is determined at the shift command timing determining step that the shift command was issued at a timing at which the shift operation was not being conducted, a first shift operation in which the disengagement operation of the clutch and the dog insert operation of the transmission are conducted in accordance with a first schedule and then the engagement operation of the clutch is conducted in the shift control step, and wherein, when it is determined at the shift command timing determining step that the shift command was issued at a timing at which the shift operation and the engagement operation of the clutch were being conducted, the engagement operation of the clutch is interrupted and a second shift operation in which the disengagement operation of the clutch and the dog insert operation of the transmission are conducted in accordance with a second schedule that is different from the first schedule and then the engagement operation of the clutch is conducted in the shift control step.

With the device and the method for controlling the transmission mechanism and the method for controlling the motor vehicle according to the present invention, in a motor vehicle having a clutch and a dog clutch transmission actuated by an actuator such as a motor, an additional shift command can be accepted during a shift operation, thereby providing control that makes possible a responsive shift operation.

DETAILED DESCRIPTION

Hereinafter, various embodiments according to the present invention are described in detail with reference to the drawings. It is to be understood that other embodiments may be utilized and structural changes may be made.

FIG. 1illustrates an external side view of a motorcycle according to one embodiment of the present invention. As in any typical motorcycle, a motorcycle1shown in theFIG. 1includes a body frame10, a front wheel11that is a steering wheel, a rear wheel12that is a driving wheel, a seat13on which a rider sits, a fuel tank14, handlebars20, an engine30, and a transmission mechanism40. The motorcycle is described here as an example of a motor vehicle; however, the present invention is applicable to various vehicles such as an all-terrain vehicle (ATV), a three-wheeled or four-wheeled buggy, and a snowmobile.

FIG. 2is a schematic view of the handlebars20. A right grip21R on the handlebars20shown in the figure is an accelerator grip. A rider can adjust the degree of the accelerator opening by twisting the right grip21R. While acceleration of the motorcycle1is preferably controlled by twisting the right grip21R, it can be controlled by other acceleration input devices including throttle buttons or levers, pedals, or other acceleration input means without departing from the scope of the present invention.

An accelerator opening detector22attached to the right grip21R detects the degree of accelerator opening adjusted by the rider. A shift switch23attached to a left grip21L on the handlebars20serves as a shift command receiving unit. The shift switch23includes an upshift switch23aand a downshift switch23b. The rider can successively select a gear stage of the transmission mechanism40from neutral through to the top gear by manually operating the upshift switch23aand the downshift switch23b. The shift command receiving unit is not limited to the shift switch23, and other input devices such as a shift pedal may be used.

An indicator24is preferably disposed at the center of the handlebars20so as to indicate the present gear stage; however, the indicator24can be disposed in any position where it can be easily viewed by a rider on the motorcycle1.

FIG. 3is a schematic view showing one embodiment of the transmission mechanism40. Power generated by the engine30is transmitted through a primary drive gear32on a crankshaft31to a primary driven gear41in the transmission mechanism40. An engine tachometer33is attached to an end of the crankshaft31. The gear ratio of the primary drive gear32to the primary driven gear41is called the primary reduction ratio.

The power that is input to the primary driven gear41is transmitted to a main shaft43through a clutch42. Although a wet multiple disc clutch is shown inFIG. 3, the clutch42is not limited to being of this type. Various known clutches such as a dry clutch and a single disc clutch may be preferably used. Transmission gears44for multiple gear stages are disposed on the main shaft43. The transmission gears44mesh with transmission gears46disposed on a drive shaft45. Although the transmission gears44and46are separated inFIG. 3, they mesh with each other in reality, as described above. The power is transmitted from the main shaft43to the drive shaft45through only a selected pair of the transmission gears44and46, while the remaining transmission gears44and46rotate freely. The pair of transmission gears44and46that transmits the power is selected by rotating a shift cam47and thereby moving a shift fork48. The main shaft43, the transmission gears44, the drive shaft45, the transmission gears46, the shift cam47, and the shift fork48constitute one embodiment of a transmission50known as a dog clutch transmission.

Regarding gear shifting in the dog clutch transmission, it is known that a shift operation can be conducted more reliably when a dog insert operation and a clutch disengagement operation are conducted at specified timings. Moreover, in order to reliably activate the clutch and the transmission at such timings, it is desirable that positions of the clutch and the transmission be definite when shift control starts. Since the positions of the clutch and transmission are indefinite during the shift operation, it is not desirable that the shift control start during the shift operation.

FIG. 4is a diagram showing a structure of one of the transmission gears44. The transmission gear44includes a first gear44awith dogs80on its axial end face, and a second gear44bwith recesses81on its axial end face. The first gear44ais fitted onto the main shaft43extending through a splined hole82such that the first gear44adoes not rotate relative to the main shaft43but can be moved in the direction along the axis of main shaft43. The second gear44bis mounted on the main shaft43such that the second gear44bcan rotate freely.

The first gear44acan be moved in the axis direction using the shift fork48. When the dogs80on the first gear44ado not mesh with the recesses81in the second gear44b,the power that is input to the main shaft43is not transmitted to the second gear44b,because the first gear44aand the second gear44brotate freely relative to each other. When the dogs80on the first gear44aare inserted into the recesses81in the second gear44b,the first gear44aand the second gear44brotate together so that the power that is input to the main shaft43is transmitted to the drive shaft45through the second gear44band to the transmission gear46that meshes with the second gear44b.

The main shaft43and the drive shaft45are provided with respective transmission gears44and46, each of which include gears similar to the first gear44aand the second gear44b. The transmission50changes the reduction ratio at which the power is transmitted from the main shaft43to the drive shaft45by appropriately selecting a combination of the transmission gear44and the transmission gear46whose dogs80and recesses81mesh with each other.

When a dog insert operation is attempted, the first gear44ais moved in the axis direction toward the second gear44b,the dogs80may contact an axial end face83of the second gear44binstead of contacting the recesses81. In this case, if the first gear44aand the second gear44brotate at the same speed, the shift operation is disabled. This condition is called a dog contact state. In order to prevent a dog contact state, and reliably conduct the shift operation, a torque should be applied to one of the first gears44aand the second gear44bso that the first and second gears rotate relative to each other in sliding contact. Specifically, the torque can be provided to the first gear44athrough the main shaft43by conducting the dog insert operation and the disengagement operation of the clutch at specified timings so that the dogs are inserted while the clutch42is partially engaged.

The power transmitted to the drive shaft45is transmitted to the rear wheel12through a well-known power transmission mechanism (not shown), such as a chain mechanism, a belt mechanism, or a shaft drive mechanism so as to drive the motorcycle1. The ratio between the rotation speed of the drive shaft45and the rear wheel12, which is generated by the power transmission mechanism, is known as a secondary reduction ratio. A drive shaft tachometer49is attached to the end of the drive shaft45to measure the speed of the drive shaft45.

FIG. 5is a block diagram of a control system of the motorcycle1. Sensors and switches70, a main switch71that is linked to the key switch, a battery72for supplying power to a control device60, the clutch actuator51, and the shift actuator52are connected to the control device60.

The control device60includes a controller61, a power supply circuit62, and motor drivers63and64. The controller61includes a known computer such as a digital signal processor (DSP) or a micro controller. Various data that indicates the states of various parts of the motorcycle1, and the commands issued by a rider, are input from the sensors and switches70to the controller61. On the basis of the data, the controller61controls the transmission mechanism40by sending signals to the motor drivers63and64and thereby actuating the clutch actuator51and the shift actuator52. A program for operating the controller61is provided in non-volatile memory such as ROM or flash memory in the controller61. The power supply circuit62, which is linked to the main switch71, adjusts voltage, current, and other electrical properties, of the electric power that is supplied from the battery72, and supplies the electric power to the controller61. The motor driver63receives the electric power from the battery72and actuates the clutch actuator51in accordance with a signal sent from the controller61. Similarly, the motor driver64actuates the shift actuator52.

FIG. 6is a diagram illustrating a structure of the sensors and switches70connected to the control device60in one embodiment. As shown, the sensors and switches70include the accelerator opening detector22, the upshift switch23a,the downshift switch23b,the engine tachometer33, the drive shaft tachometer49, the clutch actuator position detector54, the potentiometer56, and the gear position detector57. Data obtained from the sensors and switches70are input to the controller61as required.

Hereinafter, control for conducting a shift operation of a running motorcycle1, having the above-described structure, is described in detail.

FIG. 7is a flowchart showing an algorithm for control that is conducted by the control device60when a rider inputs a shift command while the motorcycle1is running. With reference to the flowchart, the control device60detects that the rider pressed the upshift switch23aor the downshift switch23band receives a shift command (step S0). A shift command to shift a gear to a nonexistent gear position, such as a downshift command from the neutral position or an upshift command from the top gear, is rejected.

Upon receiving the shift command, the control device60determines the timing at which the shift command was issued and the state of the motorcycle1at that time. Specifically, the control device60determines whether a shift operation is being conducted in the motorcycle1at that time (step S1) and whether an engagement operation of the clutch42is being conducted (step S10). In one preferred embodiment, the control device60determines whether a shift operation is being conducted in the motorcycle1at that time by checking a value of an internal flag stored in the control device60. The value of the internal flag is set so as to indicate whether a shift operation is being conducted in the motorcycle1. Methods to determine the timing of the shift command are not limited to the use of an internal flag. For example, a time elapsed since the shift operation was started may be used, or an operating state of the shift arm may be checked.

If a shift operation is being conducted, the control device60determines whether an engagement operation of the clutch42is being conducted by checking the content of the signal sent from the controller61to the motor driver63. In a program for making these checks, a determining unit for determining the timing at which the shift command was issued is implemented in software.

If at the time a shift command is received, a shift operation is not being conducted in the motorcycle1, the control device60proceeds to step S2and changes the value of the internal flag to a value indicating that a shift operation is being conducted. Then, the control device60reads a first schedule for conducting a disengagement operation of the clutch42and activation of the transmission50from memory (step S3). The memory, which is not shown, could be ROM, EPROM, Flash or any other type of data storage device. The first schedule includes data such as timings at which the clutch42and the transmission50are to be activated, conditions for starting the operation, and speeds of the operation.

In step S4, the clutch42is disengaged and the transmission50is activated in accordance with the first schedule so as to shift up or down a gear. At this time, because a gear is shifted up or down while the clutch42is being moved to the disengaged position as described below, the dog insert operation in the transmission50is conducted while the clutch42is partially engaged.

When the clutch42is disengaged and the dog insert operation in the transmission50is completed, the control device60reads a clutch engagement map90from memory (not shown) such as ROM (step S5).

FIG. 8is a graph showing the clutch engagement map90. The horizontal axis represents a difference in rotation speed between the input and output sides of the clutch42, and the vertical axis represents a moving speed of the clutch actuator51. For each gear position to be shifted to, the relationship between the difference in the rotation speeds and the moving speed of the clutch actuator is shown with a line.

The control device60engages the clutch42by driving the clutch actuator51with the motor driver63on the basis of the moving speed of the clutch actuator51obtained from the clutch engagement map90in accordance with the difference in rotation speed between the input and output sides of the clutch42(step S6). The rotation speed of the input side of the clutch42is calculated by multiplying the primary reduction ratio and the output of the engine tachometer33, which is data related to the rotation speed of the input side of the clutch42. The rotation speed of the output side of the clutch42is calculated by multiplying the present gear ratio of the transmission50and the output data of the drive shaft tachometer49provided for detecting a vehicle speed, which is data related to the rotation speed of the output side of the clutch42. The present gear ratio of the transmission50can be obtained by detecting a gear position with the gear position detector57.

In the above-described steps S3to S6, a first shift operation according to the first schedule is conducted. During the first shift operation, the control device60serves as a shift control unit that conducts the disengagement and engagement operations of the clutch42and the shift operation including the dog insert operation of the transmission50in accordance with the shift command.

When the engagement of the clutch42is completed, the control device60returns the shift arm55to the neutral position (step S7), changes the value of the internal flag to a value indicating that a shift operation is not being conducted (step S8), and terminates the control for the shift operation (step S9).

FIG. 9is a graph showing the behavior of the motorcycle1during the first shift operation. Lines in sections of the graph show, from top to bottom, an input to the shift switch23, a position of the clutch actuator, a position of the shift arm, and a change of the gear position in the transmission50. The horizontal axis represents time for all sections of the graph.

Looking first at the top line on the graph representing the input to the shift switch23, the middle position in the graph shows a state in which there is no input, the “UP” position shows a state in which the upshift switch23ais pressed, and the “DOWN” position shows a state in which the downshift switch23bis pressed.

Examining next the second line down from the top on the graph regarding the clutch actuator position, the area above the line labeled “disengaged position” in the graph shows a state in which the clutch42is disengaged, the area below the line labeled “engaged position” shows a state in which the clutch42is engaged, and the area between these positions shows a state in which the clutch42is partially engaged.

Regarding the third line down in the graph labeled shift arm position, the “NEUTRAL” position in the graph shows a state in which the shift arm55is in the neutral position. The “UPSHIFT” position shows a state in which the shift cam47is rotated by the shift arm55by a certain angle in the upshift direction. The “DOWNSHIFT” position shows a state in which the shift cam47is rotated by the shift arm55by a certain angle in the downshift direction.

Lastly, the bottom line of the graph labeled gear position shows a gear position of the transmission50corresponding to a rotation angle of the shift cam47.

Described below is a case in which a rider presses the downshift switch23bwhile the motorcycle1is cruising in the fourth gear. Note that similar control is exercised when a rider presses the upshift switch23a.

InFIG. 9, the area denoted by A represents a state in which the motorcycle1is cruising. At this time, as shown inFIG. 9, the shift switch23is not pressed, the clutch actuator51is in the engaged position, the shift arm55is in the neutral position, and the gear position is in fourth gear. When a rider presses the downshift switch23b,B inFIG. 9, the control device60determines whether a shift operation is being conducted in the motorcycle1. Since the motorcycle1is cruising in this case, the control device60determines that a shift operation is not being conducted. Then, following the above algorithm illustrated inFIG. 7, the value of the internal flag is changed to a value indicating that a shift operation is being conducted, and a first schedule is read.

The first schedule includes a timing and speed at which the clutch42is caused to start to move toward the disengaged position, and a timing and speed at which the shift arm55is caused to start to rotate in an upshift or a downshift direction. As shown inFIG. 9, the clutch actuator51is caused to start to move as soon as the downshift switch23bis pressed. Then, after a predetermined period denoted by C inFIG. 9, the shift arm55starts to rotate, D inFIG. 9, so as to start to rotate the shift cam47, E inFIG. 9, and change the gear position of the transmission50from fourth to third. At this time, a pair of the transmission gears44and46in the transmission50that were meshed with each other to provide the fourth gear ratio become unmeshed. Subsequently, a pair of the transmission gears44and46in the transmission50become meshed with each other to provide the third gear ratio. The meshing of the transmission gears is effectuated when a dog insert operation is conducted. Dogs80on a first gear44aare inserted into the recesses81on a second gear44b. The dog insert operation occurs on a set of gears44on the main shaft43and on a set of gears46on the drive shaft45respectively so that the transmission gears44and46are meshed together. The length of the predetermined period, C inFIG. 9, is set such that the dog insert operation is conducted while the clutch42is partially engaged.

When the clutch actuator position detector54detects that the clutch actuator51has reached the disengaged position, F inFIG. 9, and the gear position detector57detects that the gear position has been changed to third gear, G inFIG. 9, the control device60reads the clutch engagement map90.

In the area denoted by H, the control device60reads output from the engine tachometer33and the drive shaft tachometer49as necessary, calculates the difference between the rotation speeds of the input and output sides of the clutch42, and moves the clutch actuator51in accordance with the moving speed obtained from the clutch engagement map90.

When it is detected that the clutch actuator51is in an engaged position, I inFIG. 9, the control device60returns the shift arm to the neutral position, J inFIG. 9, changes the value of the internal flag to a value indicating that a shift operation is not being conducted, switches to a cruising mode, and terminates the shift operation.

Referring back toFIG. 7, an example of when step SI determines that a shift operation is being conducted in the motorcycle1will now be described. When the internal flag indicates that a shift operation is being conducted in the motorcycle1, the control device60proceeds to step S10to determine whether the clutch42is in an engagement operation.

If the clutch42is not in an engagement operation, the control device60rejects and cancels a new shift command (step S14) and continues the present shift operation. In this case, a buzzer or a display in the indicator24, for example, may indicate to the rider that the shift command is canceled. If the clutch42is in an engagement operation, the control device60proceeds to step S11and determines whether to accept the shift command that is input during the shift operation.

If the rider inputs a new shift command at a time when the present shift operation has almost finished, the control device60accepts the shift command so as to respond to the shift command quickly issued by the rider. By accepting the new shift command, which was input at a time when the rider felt that the present shift operation had finished but in fact the control had not yet finished, instead of cancelling it, the rider is provided with a natural, comfortable, and responsive driving sensation. On the other hand, if the rider inputs a new shift command at a time when the present shift operation is not almost finished, it is likely that the shift command is an improper operation. A shift operation at such timing would damage a comfortable driving sensation. In such a case, the control device60rejects and cancels the new shift command (step S14).

Specifically, the timing can be determined by applying the condition that (1) the difference in rotation speed between the input and output sides of the clutch42is equal to or less than a predetermined value. This is because, if the difference in rotation speed between the input and output sides of the clutch42is equal to or less than a predetermined value of, for example, 100 rpm, the shift operation is almost finished. Moreover, the following conditions may be added: (2) the clutch actuator position is situated closer to the engaged position than a set position, and (3) a predetermined period elapses while the conditions (1) and (2) are satisfied. The predetermined period may be set at, for example, 20 ms. Obviously, the predetermined value and the predetermined period may be appropriately set such that a comfortable driving sensation is provided. The program for the determination includes a determining unit that is implemented in software. The determining unit determines whether the difference in rotation speed between the input and output sides of the clutch42is less than a predetermined value on the basis of the data related to the rotation speeds of the input and output sides of the clutch42.

When the control device60determines to accept the shift command that is input during the shift operation, the control device60reads a second schedule for disengaging the clutch42and activating the transmission50from memory (not shown) such as ROM, step S12inFIG. 7. As in the first schedule, the second schedule includes data such as timings at which the clutch42and the transmission50are to be activated, conditions for starting the operation, and speeds of the operation.

In step S13, the engagement operation of the clutch42is interrupted, and the clutch42and the transmission50are activated in accordance with the second schedule so as to shift up or down a gear. As describe below, the second schedule differs from the first schedule in that, even when a new shift operation is started during the present shift operation, the dog insert operation of the transmission50is conducted while the clutch42is partially engaged by shifting up or down a gear while the clutch actuator51is moved toward the disengaged position.

When the clutch42is disengaged and the dog insert operation of the transmission50is finished, the flow proceeds to step S5. Subsequent steps are as described above. On the basis of steps S12, S13, S5, and S6described above, the second shift operation according to the second schedule is conducted.

The second shift operation is conducted, not only when a new shift command is input during the first shift operation, but also when a new shift command is input during the second shift operation.

FIG. 10is a graph showing behavior of the motorcycle1in a first example of the second shift operation. As inFIG. 9, lines in sections of the graph show, from top to bottom, an input to the shift switch23, a position of the clutch actuator, a position of the shift arm, and a change of the gear position in the transmission50. The horizontal axis represents time for all sections of the graph.

An example in which a rider pressed the downshift switch23bduring the first shift operation described above with reference toFIG. 9is illustrated inFIG. 10and described here. The parts denoted by A to G inFIG. 10are the same as inFIG. 9as described above. The area denoted by H′ inFIG. 10represents that the control device60performs control so as to move and engage the clutch actuator51on the basis of the clutch engagement map90.

When the downshift switch23bis pressed again, K inFIG. 10, the control device60determines whether to accept the shift command that is input during the present shift operation, step S11inFIG. 7. In this case, because the difference in speed between the input and output sides of the clutch42is equal to or less than a predetermined value, as an example 100 rpm, the shift command is accepted and the second schedule is read, Step S12inFIG. 7.

The second schedule includes timing and speed at which the shift arm55is caused to start to rotate toward the neutral position, timing and speed at which the clutch actuator51is caused to start to move toward the disengaged position, and timing and speed at which the shift arm55is caused to start to rotate in the upshift or downshift direction. At the position shown by K inFIG. 10, the shift arm55is in the downshift position. In the second schedule, the shift arm55is first caused to start to move toward the neutral position, while the clutch actuator position is maintained, numeral100inFIG. 10. After a predetermined period L inFIG. 10, the clutch actuator51starts to move in a disengagement direction, M inFIG. 10. After a predetermined period N, the shift arm55starts rotating, O inFIG. 10, thereby rotating the shift cam47, P inFIG. 10, and changing the reduction ratio of the transmission50from third to second. By delaying the movement of the clutch actuator51in the disengagement direction by the predetermined period L as shown inFIG. 10, the dog insert operation is conducted while the clutch42is partially engaged, and in particular, while the clutch42is moving in the disengagement direction in a partially engaged state. The predetermined periods L and N may be set appropriately such that the dog insert operation is conducted reliably.

Then, when the clutch actuator position detector54detects that the clutch actuator51has reached the disengaged position, Q inFIG. 10, and the gear position detector57detects that the gear position has been changed to second, R inFIG. 10, the control device60reads the clutch engagement map90and moves the clutch actuator51in accordance with the map, area S inFIG. 10.

When it is detected that the clutch actuator51has reached the engaged position, T inFIG. 10, the control device60returns the shift arm to the neutral position, U inFIG. 10, changes the value of the internal flag to a value indicating that a shift operation is not being conducted, and switches to a cruising mode, and terminates the shift operation.

In the above description, the movement of the clutch actuator51in the disengagement direction was delayed by the predetermined period L. Alternatively, the movement of the clutch actuator51in the disengagement direction may be delayed until it is detected that the shift arm55has reached a predetermined position. That is, the clutch actuator position may be maintained at the present position until the shift arm reaches the point V inFIG. 10. The position of the shift arm55can be obtained from the output value of the potentiometer56attached to the shift actuator52.

A method for delaying the movement of the clutch actuator51in the disengagement direction is not limited to the method of maintaining the clutch actuator position. Alternatively, as shown by numeral101inFIG. 10, the clutch actuator51may be moved to a predetermined position after accepting the shift command, and then moved in the disengagement direction after a predetermined period. As a further alternative, as shown by numeral102inFIG. 10, the dog insert operation may be conducted while the clutch42is moved in the disengagement direction in a partially engaged state by moving the clutch actuator51slower than in the first schedule.

FIG. 11is a graph showing behavior of the motorcycle1in a second example of the second shift operation. As inFIGS. 9 and 10, lines in sections of the graph show, from top to bottom, an input to the shift switch23, a position of the clutch actuator, a position of the shift arm, and a change of the gear position in the transmission50. The horizontal axis represents time for all the sections. In the following description, like numerals denote like parts in the above-described first example described inFIG. 10. Overlapping descriptions are omitted.

This example differs from the first example in that, when it is detected that the gear position has been changed to third gear at time G inFIG. 11, the shift arm is immediately controlled and returned to the neutral position. Therefore, by the time when the control device60accepts an additional shift command during the first shift operation at time K inFIG. 11, the shift arm55is already returned to the neutral position.

In the second schedule in this example, the clutch actuator51is immediately caused to start to move, because it is not necessary that the movement of the clutch actuator51in the disengagement direction be delayed so as to wait until the shift arm55returns to the neutral position, as in the first example. Then, since the clutch actuator51starts to move the clutch42from the partially engaged position toward the disengaged position, the disengagement operation by the clutch actuator51is conducted earlier than in the first schedule in which the clutch42is caused to start to move from the engaged position toward the disengaged position.

Therefore, a predetermined period W from time K to time O inFIG. 11, at which time the shift arm55begins to rotate, is shorter than the predetermined period C in the first schedule. Therefore, the dog insert operation in the transmission50in the second schedule is started earlier than the dog insert operation of the transmission50in the first schedule. The length of the predetermined period W may be appropriately set such that the dog insert operation is conducted reliably. Alternatively, the length of W may be set in accordance with the output value of the clutch actuator position detector54that detects the position of the clutch actuator51at time K. The nearer the clutch actuator51is to the disengaged position at time K, the shorter the predetermined period W; the nearer the position of the clutch actuator51to the engaged position at time K, the longer is the predetermined period W.

The shift cam47starts rotating with the rotation and the movement of the shift arm55, P inFIG. 11, so that the gear ratio of the transmission50is changed from third to second. When the clutch actuator position detector54detects that the clutch actuator51has reached the disengaged position, Q inFIG. 11, and the gear position detector57detects that the gear position is changed to second, R inFIG. 11, the control device60moves the shift arm55to the neutral position and reads the clutch engagement map90. According to the clutch engagement map90, the control device60moves the clutch actuator51, area S inFIG. 11.

When it is detected that the clutch actuator51is at the engaged position, T inFIG. 11, the control device60changes the internal flag to a value indicating that a shift operation is not being conducted, switches to the cruising mode, and terminates the shift operation.

Although it is assumed in the above description that a rider manually issues a shift command, a computer such as the control device60may issue a shift command by automatic control.

As heretofore described, with the control device and method for the transmission mechanism of the motor vehicle and the motor vehicle according to the present invention, in the motor vehicle equipped with a clutch actuated by an actuator such as a motor and a dog clutch transmission, an additional shift command can be accepted during a shift operation, thereby enabling control for a responsive shift operation.