Belt-type continuously variable transmission control device and control method

Abstract

To provide a constitution capable of controlling a continuously variable transmission to have a desired change gear ratio while reducing the number of components in a transmission case.SOLUTION: A continuously variable transmission 10 includes: a driving pulley to which driving power from an output shaft of a power source of a vehicle is transmitted; a driven pulley including a centrifugal clutch; and a belt laid therebetween. A control device 170 of the continuously variable transmission includes a control portion 182 for controlling the motor for moving a movable pulley half body to a fixed pulley half body of the driving pulley. The control portion 182 controls the motor 120 to keep a change gear ratio of the continuously variable transmission at a fixed gear change rate when the centrifugal clutch 100 is kept in a state of non-complete connection, and feedback controls an operation of the motor 120 on the basis of a detected vehicle velocity and a detected power source load when the centrifugal clutch 100 is kept in a state of complete connection.SELECTED DRAWING: Figure 18

Description

[Technical field]

[0001] The present invention relates to a control device and a control method for a belt-type continuously variable transmission including a drive pulley to which a driving force is transmitted, a driven pulley, and a belt stretched between them. [Background technology]

[0002] Conventionally, a belt-type continuously variable transmission has been adopted between an internal combustion engine as a power source and drive wheels in a saddle-type vehicle. The belt-type continuously variable transmission includes a drive pulley to which drive force is transmitted, a driven pulley to which power is transmitted to the drive wheels, a V-belt stretched between them, and a mechanism for changing the groove width of the pulleys.

[0003] For example, in the V-belt type continuously variable transmission of Patent Document 1, a shift member is connected to a hub shaft of a movable pulley half of a drive pulley so as to rotate relatively and to be immovable in the axial direction. An electric motor is attached so that its rotor shaft is parallel to an input shaft to which the drive pulley is attached, and a shift control mechanism is provided to operate the shift member in the axial direction via a reduction gear train. The shift control mechanism is composed of a screw shaft parallel to the input shaft and a female screw member with which the male screw portion of the screw shaft is screwed, and the screw shaft is supported by bearings on the inner and outer cases of the transmission case on the radial outside of the drive pulley. The female screw member is integrally connected to the tip of the arm of the shift member. Therefore, when the electric motor is operated and the screw shaft rotates forward, the female screw member is sent to move the shift member toward the top, and the movable pulley half approaches the fixed pulley half of the drive pulley. Conversely, when the screw shaft is rotated in the reverse direction, the female screw member is sent to move the shift member in the low direction, moving the movable pulley half away from the fixed pulley half.

[0004] Patent Document 2 discloses an electronically controlled continuously variable transmission that performs feedback control so that the gear ratio between the input shaft and the output shaft becomes a target gear ratio. It is disclosed that this continuously variable transmission uses a sheave position sensor for detecting the position of the movable sheave body of the primary sheave, a primary sheave rotational speed sensor, a secondary sheave rotational speed sensor, a vehicle speed sensor, and a throttle opening sensor to control the gear ratio. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-029130 A [Patent Document 2] Patent No. 5030608 Summary of the Invention [Problem to be solved by the invention]

[0006] The continuously variable transmission of Patent Document 2 has a large number of parts, such as sensors, which makes it difficult to layout the continuously variable transmission inside the transmission case and increases costs. The object of the present invention is to provide a configuration that makes it possible to control the continuously variable transmission to a target gear ratio while reducing the number of parts inside the transmission case. [Means for solving the problem]

[0007] The first aspect of the present invention is A control device for a belt-type continuously variable transmission including: a drive pulley to which a driving force is transmitted from an output shaft of a power source of a vehicle; a driven pulley equipped with a centrifugal clutch which rotates integrally with the driven pulley and is connected to the driven pulley when a predetermined rotation speed is exceeded, thereby transmitting the driving force of the power source to a drive wheel of the vehicle; and a belt stretched between the drive pulley and the driven pulley, a control unit for controlling a motor that generates a driving force in an axial direction of the movable pulley half so as to move the movable pulley half relative to the fixed pulley half in the drive pulley, The control unit is controlling the motor so as to maintain a gear ratio of the continuously variable transmission at a fixed gear ratio when the centrifugal clutch is in an incompletely engaged state; feedback controlling the operation of the motor based on a detected vehicle speed and a detected load of the power source when the centrifugal clutch is in a fully engaged state; Run A control device for a belt-type continuously variable transmission, to provide.

[0008] According to the above configuration, when the centrifugal clutch is not fully engaged, that is, when the centrifugal clutch is slipping or disengaged, the motor is controlled to maintain the gear ratio of the continuously variable transmission at a fixed gear ratio. Therefore, when the centrifugal clutch is not fully engaged, the motor can be controlled without the need to accurately grasp the driving state of the driven pulley, for example, its rotational speed, and the gear ratio of the continuously variable transmission can be controlled to a fixed gear ratio. Therefore, for example, a sensor that detects the rotational speed of the driven pulley can be omitted from the case of the continuously variable transmission. In this way, according to the above configuration, it is possible to control the gear ratio to a target ratio while reducing the number of parts in the transmission case. Note that when the centrifugal clutch is fully engaged, when feedback control of the operation of the motor is performed based on the detected vehicle speed and the detected load of the power source, the feedback control is possible even if, for example, a sensor that detects the rotational speed of the driven pulley is not present in the transmission case.

[0009] Preferably, when controlling the motor to maintain the speed ratio of the continuously variable transmission at a fixed speed ratio, the control unit executes limiting the magnitude of the motor current to a predetermined value or less and limiting the duty ratio of the control signal to the motor to a predetermined limit value or less. According to this configuration, even if the movable pulley half hits, for example, a stopper portion, the duty ratio is limited to a predetermined limit value or less, so that the speed of movement of the movable pulley half can be slowed down and the collision load at the time of the hitting can be suppressed, thereby protecting each component. Furthermore, by limiting the magnitude of the motor current to a predetermined value or less, it is possible to prevent the continuous current flowing to the motor from becoming excessive, thereby making it possible to protect the motor.

[0010] Preferably, when the motor is controlled to maintain the speed ratio of the continuously variable transmission at a fixed speed ratio, the movable pulley half reaches a predetermined end in the axial direction of the movable pulley half. According to this configuration, when the motor is controlled to maintain the speed ratio of the continuously variable transmission at a fixed speed ratio, the movable pulley half reaches a predetermined end in the axial direction of the movable pulley half, so that the speed ratio of the continuously variable transmission can be controlled to the fixed speed ratio with simpler control.

[0011] Preferably, when the centrifugal clutch is in an incompletely connected state, the control unit executes the following: determining whether the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half, based on the current of the motor; and, when it is determined that the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half, controlling the motor so as to maintain the gear ratio of the continuously variable transmission at a fixed gear ratio. According to this configuration, it is determined whether the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half, based on the current of the motor. Therefore, it is possible to detect the arrival of the movable pulley half at the predetermined end, for example, without providing a sensor that directly detects the position of the movable pulley half. Then, when it is determined that the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half, the motor is controlled so as to maintain the gear ratio of the continuously variable transmission at a fixed gear ratio. Therefore, in controlling the continuously variable transmission, it becomes possible to move the movable pulley half over a wide range, including the point where the movable pulley half reaches a predetermined end, thereby making it possible to further expand the movable range of the movable pulley half of the drive pulley.

[0012] Preferably, when it is determined that the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half, the abutment portion on the movable pulley half abuts against a stopper portion that restricts the movement of the movable pulley half in the axial direction away from the fixed pulley half. This makes it possible to limit the abutment of the movable pulley half to the abutment portion and the stopper portion, and more reliably protect other members.

[0013] A second aspect of the present invention is A belt-type continuously variable transmission including a drive pulley to which a driving force is transmitted from an output shaft of a power source of a vehicle, a driven pulley equipped with a centrifugal clutch which rotates integrally with the driven pulley and is connected when a predetermined rotation speed is exceeded to transmit the driving force of the power source to a drive wheel of the vehicle, and a belt stretched between the drive pulley and the driven pulley, the control method comprising: controlling a motor which generates a driving force in an axial direction of a movable pulley half so as to move the movable pulley half relative to a fixed pulley half in the drive pulley, controlling the motor so as to maintain a gear ratio of the continuously variable transmission at a fixed gear ratio when the centrifugal clutch is in an incompletely engaged state; feedback controlling the operation of the motor based on a detected vehicle speed and a detected load of the power source when the centrifugal clutch is in a fully engaged state; Includes A control method comprising: to provide.

[0014] According to the configuration of the second aspect, when the centrifugal clutch is not fully engaged, that is, when the centrifugal clutch is slipping or disengaged, the motor is controlled to maintain the gear ratio of the continuously variable transmission at a fixed gear ratio. Therefore, when the centrifugal clutch is not fully engaged, the motor can be controlled without the need to accurately grasp the driving state of the driven pulley, for example, its rotational speed, and the gear ratio of the continuously variable transmission can be controlled to a fixed gear ratio. Therefore, for example, a sensor that detects the rotational speed of the driven pulley can be omitted from the case of the continuously variable transmission. In this way, according to the above configuration, it is possible to control the gear ratio to a target ratio while reducing the number of parts in the transmission case. Note that when the centrifugal clutch is fully engaged, feedback control of the operation of the motor based on the detected vehicle speed and the detected load of the power source is possible even if, for example, a sensor that detects the rotational speed of the driven pulley is not present in the transmission case.

[0015] Preferably, the second aspect further includes a step of limiting the magnitude of the motor current to a predetermined value or less and limiting the duty ratio of the control signal to the motor to a predetermined limit value or less when controlling the motor to maintain the speed ratio of the continuously variable transmission at a fixed speed ratio. According to this configuration, even if the movable pulley half hits, for example, a stopper, the duty ratio is limited to a predetermined limit value or less, so that the speed of movement of the movable pulley half can be slowed down and the collision load at the time of the hitting can be suppressed, thereby protecting each component. Furthermore, by limiting the magnitude of the motor current to a predetermined value or less, it is possible to prevent the continuous current flowing to the motor from becoming excessive, thereby making it possible to protect the motor.

[0016] Preferably, in the second aspect, when the centrifugal clutch is in an incompletely connected state, the step of controlling the motor to maintain the speed ratio of the continuously variable transmission at a fixed speed ratio includes a step of determining, based on a current of the motor, whether or not the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half when the centrifugal clutch is in an incompletely connected state, and a step of controlling the motor to maintain the speed ratio of the continuously variable transmission at a fixed speed ratio when it is determined that the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half. According to this configuration, it is determined, based on a current of the motor, whether the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half. Therefore, it is possible to detect the arrival of the movable pulley half at the predetermined end without providing a sensor that directly detects the position of the movable pulley half, for example. Then, when it is determined that the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half, the motor is controlled to maintain the speed ratio of the continuously variable transmission at the fixed speed ratio. Therefore, in controlling the continuously variable transmission, it becomes possible to move the movable pulley half over a wide range, including the point where the movable pulley half reaches a predetermined end, thereby making it possible to further expand the movable range of the movable pulley half of the drive pulley. Effect of the Invention

[0017] According to the first or second aspect of the present invention, since the above configuration is provided, in controlling the continuously variable transmission, it is possible to control the transmission to a target gear ratio while reducing the number of parts in the transmission case. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic left side view of a motorcycle equipped with a power unit equipped with a belt-type continuously variable transmission according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a front view of the power unit of FIG. [Diagram 3] FIG. 3 is a sectional development of the power unit taken along line III-III in FIG. [Figure 4] FIG. 4 is an enlarged view of the drive pulley and its drive system shown in FIG. [Diagram 5] FIG. 5 is an enlarged view of the drive pulley and its drive system in FIG. 3, showing the movable drive pulley half body when it has moved as indicated by the dashed line in FIG. [Figure 6] 6 is a front view of a movable holder in the belt-type continuously variable transmission of FIG. 1. FIG. [Figure 7] 7 is a perspective view of an inner boss of a cam assist mechanism in the belt-type continuously variable transmission of FIG. 1. FIG. [Figure 8] FIG. 8 is a perspective view showing a state in which a ball member is disposed on an inner boss of a cam assist mechanism in the belt-type continuously variable transmission of FIG. [Figure 9] FIG. 9 is a perspective view showing a part of an outer boss around the inner boss in which the ball of FIG. 8 is disposed. [Figure 10] FIG. 10 is a cross-sectional view taken along line XX in FIG. [Figure 11] 11 is a perspective view of an outer boss of a cam assist mechanism in the belt-type continuously variable transmission of FIG. 1. FIG. [Figure 12] 12 is a cross-sectional view of the belt-type continuously variable transmission of FIG. 1 at the position of one ball member in the cam assist mechanism. [Figure 13] 13 is a simplified diagram showing the relationship between a groove portion and an axis line, as viewed from an arrow XIII in FIG. 7, in an inner boss of a cam assist mechanism in the belt-type continuously variable transmission in FIG. [Figure 14] 14 is a perspective view of a case that houses a drive mechanism in the belt-type continuously variable transmission of FIG. 1 and a part of its surroundings, seen obliquely from the front. [Figure 15] 15 is a perspective view of a case that houses a drive mechanism in the belt-type continuously variable transmission of FIG. 1 and a part of its surroundings, seen obliquely from behind. [Figure 16] FIG. 16 is a diagram showing a gear arrangement of a drive mechanism in the belt-type continuously variable transmission of FIG. 1, as viewed from the left axial direction of a case in which the drive mechanism is housed. [Figure 17] FIG. 17 is a cross-sectional view taken along line XVII-XVII in FIG. [Figure 18] FIG. 18 is a block diagram of the control device for the motorcycle of FIG. [Figure 19] FIG. 19 is a graph showing data for controlling the motor of the drive mechanism in the belt-type continuously variable transmission of FIG. [Figure 20] FIG. 20 is a flowchart of the control of the motor of the drive mechanism in the belt-type continuously variable transmission of FIG. [Figure 21] FIG. 21 is a timing chart relating to the control of the motor of the belt-type continuously variable transmission of FIG. [Figure 22] FIG. 22 is a timing chart relating to the control of the motor of the belt-type continuously variable transmission of FIG. [Figure 23] FIG. 23 is a timing chart relating to the control of the motor of the belt-type continuously variable transmission of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] A belt-type continuously variable transmission 10 according to one embodiment will be described with reference to Figures 1 to 15. Note that the directions of front, rear, left, right, up, down, etc. in the description and claims of this specification correspond to the directions of a saddle-type vehicle equipped with a power unit P equipped with the belt-type continuously variable transmission 10 according to this embodiment. In this embodiment, the saddle-type vehicle is specifically a scooter-type motorcycle (hereinafter simply referred to as "motorcycle") 1. In the drawings, the arrow FR indicates the front of the saddle-type vehicle according to this embodiment, LH indicates the left side of the vehicle, RH indicates the right side of the vehicle, and UP indicates the top of the vehicle.

[0021] Fig. 1 shows an outline of the left side of a motorcycle 1 equipped with a power unit P that employs a belt-type continuously variable transmission 10 according to this embodiment. Fig. 2 is an enlarged view of the power unit P in Fig. 1. Fig. 3 is a cross-sectional development of the power unit P along III-III in Fig. 1. Figs. 4 and 5 are enlarged views of a portion of the belt-type continuously variable transmission 10 in Fig. 3, and are diagrams showing the movement of the belt-type continuously variable transmission 10.

[0022] In the motorcycle 1 of this embodiment, the front body 1f and the rear body 1r are connected via a low floor portion 1c, and the body frame forming the skeleton of the vehicle body is generally composed of a down tube 3 and a main pipe 4. That is, the down tube 3 extends downward from the head pipe 2 of the front body 1f, the down tube 4 is bent horizontally at its lower end and extends rearward below the floor portion 1c, and a pair of left and right main pipes 4 are connected to its rear end, and the main pipes 4 rise upward from the connecting portion, bend, and extend diagonally rearward.

[0023] A seat 5 is disposed above the main pipe 4. Meanwhile, at the front body 1f, a handlebar 6 is provided above and journaled on the head pipe 2, and a front fork 7 extends below and journals a front wheel Wf at its lower end. A power unit P is mounted on the motorcycle 1 and supported by the main pipe 4.

[0024] A main stand 8 is provided below the power unit P so as to be freely raised and lowered. The main stand 8 has an operating arm 8b extending leftward from a leg 8a, and a footrest plate 8c at its tip.

[0025] The power unit P has an internal combustion engine E at the front, and a power transmission section T extending rearward from the internal combustion engine E to the left of the rear wheel Wr. As shown in Fig. 3, the power transmission section T includes a transmission case 12 extending rearward from the internal combustion engine E, and a transmission case cover 16 that covers the transmission case 12 from the outer side in the vehicle width direction and forms a belt chamber 14, and the belt type continuously variable transmission 10 is housed in the belt chamber 14. An outer cover 18 is provided on the outer left side of the transmission case cover 16 (see Figs. 1 and 2).

[0026] The internal combustion engine E, which is the power source, is a single-cylinder, four-stroke internal combustion engine in which the cylinder block 24, cylinder head 26 and cylinder head cover 28 protrude forward from the crankcase 22, which supports the crankshaft 20 oriented in the vehicle width direction, and are tilted significantly forward to a state that is nearly horizontal.

[0027] A pair of left and right support brackets extend downward from the lower end of the crankcase 22, and these support brackets are connected via a link member 34 to a bracket 32 ​​that protrudes rearward from the front lower part of the main pipe 4, so that the power unit P is connected and supported so as to be able to swing relative to the vehicle body.

[0028] A power transmission section T extending rearward from the internal combustion engine E of the power unit P has a rear axle 36, which is an output shaft of a reduction gear mechanism Tr provided at the rear of the power transmission section T, and a rear wheel Wr, which is a drive wheel, is provided on the rear axle 36.

[0029] A rear cushion 9 is interposed between a support bracket 38 erected at the rear end of the power transmission unit T and the rear of the main pipe 4.

[0030] An intake pipe 40 extends from the upper part of the cylinder head 26 of the internal combustion engine E, which is tilted significantly forward, and curves rearward, and leads to an air cleaner 44 above the belt-type continuously variable transmission 10 via a throttle body 42 equipped with a throttle valve 42v. A fuel injection valve 45 is provided in the intake pipe 40. Meanwhile, an exhaust pipe 46 extends downward from the lower part of the cylinder head 26, bends rearward, leans to the right, and extends rearward to be connected to a muffler 48 on the right side of the rear wheel Wr.

[0031] As shown in FIG. 3, which shows a cross-sectional development of power unit P taken along line III-III in FIG. 1, crankcase 22, which supports crankshaft 20 while orienting it in the vehicle width direction, is formed by combining right-side crankcase 22r and front portion 12a of transmission case 12, which extends long from front to rear on the left side.

[0032] The transmission case 12 has a rear part 12b that extends rearward from a front part 12a to the left side of the rear wheel Wr, and is shaped like an elliptical bowl that is long from front to rear and opens to the left. A transmission case cover 16 is placed over the open left side of the transmission case 12, forming a belt chamber 14 therein, and the belt-type continuously variable transmission 10 is housed in this belt chamber 14 as described above. The right open right side of the rear part 12b of the transmission case 12 is covered by a reduction gear cover 50, forming a reduction gear chamber 52 in which the reduction gear mechanism Tr is housed. The power transmission section T is formed including the reduction gear mechanism Tr provided in the rear part 12b.

[0033] Inside the so-called crankcase 22 formed by the combination of the right crankcase 22r and the front part 12a of the transmission case 12, the crankshaft 20 is rotatably supported by each side wall of the right crankcase 22r and the front part 12a of the transmission case 12 via left and right main bearings 54, 55, which are rolling bearings.

[0034] In the internal combustion engine E, a piston 56 that reciprocates within a cylinder liner 24 a of the cylinder block 24 and a crank pin 21 of the crankshaft 20 are connected by a connecting rod 58 .

[0035] Of the outer shaft portions extending horizontally to the left and right of the crankshaft 20, a cam chain drive sprocket 60 is fitted onto the right outer shaft portion so as to be rotatable integrally therewith, and an AC generator 62 is provided at its right end, while a drive pulley 64 of the belt-type continuously variable transmission 10 is provided on the left outer shaft portion. In other words, the crankshaft 20 is the output shaft of the internal combustion engine E, and the crankshaft 20, particularly its outer shaft portion, is the input shaft of the belt-type continuously variable transmission 10.

[0036] The four-stroke internal combustion engine E of this embodiment employs an SOHC type valve system, a valve train 66 is provided inside the cylinder head cover 28, a cam chain 68 that transmits power to the valve train 66 is installed between the camshaft 70 and the crankshaft 20, and a cam chain chamber 72 for this purpose is provided in communication with the right crankcase 22r, the cylinder block 24, and the cylinder head 26. In other words, the cam chain 68 is installed through the cam chain chamber 72 between a cam chain driven sprocket 74 fitted to the right end of the camshaft 70 oriented horizontally to the left and right, and the cam chain drive sprocket 60 fitted to the crankshaft 20.

[0037] The drive pulley 64 provided on the left outer shaft portion of the crankshaft 20 in the belt-type continuously variable transmission 10 of the power unit P includes a fixed drive pulley half 64a fitted near the left end of the crankshaft 20 and a movable drive pulley half 64b that faces the fixed drive pulley half 64a on the right side and is slidable in the axial direction. The fixed pulley half of the drive pulley 64 is the fixed drive pulley half 64a, and the movable pulley half is the movable drive pulley half 64b. In this specification, the axial direction means the direction along the axis 20A of the crankshaft 20 in the power unit P, that is, the axial direction of the crankshaft 20, unless otherwise specified.

[0038] The movable drive pulley half 64b can be moved axially toward or away from the fixed drive pulley half 64a by cooperation of a variable speed drive mechanism D and a cam assist mechanism C. The variable speed drive mechanism D and the cam assist mechanism C will be described in detail later, but the cam assist mechanism C will first be briefly described here.

[0039] The cam assist mechanism C is of a ball cam type, and includes an inner boss 80, an outer boss 88, and a ball member 150 provided to engage with them.

[0040] As shown in Figures 3 to 5, particularly Figures 4 and 5, a sleeve 78, a cylindrical inner boss 80, a sleeve 82, and a fixed drive pulley half 64a are fitted from the right to the left extension from the step 76 on the left side of the main bearing 55 on the left side of the crankshaft 20, which changes to a small diameter. The sleeve 78, the inner boss 80, the sleeve 82, and the fixed drive pulley half 64a are fastened to the crankshaft 20 by fastening them with a nut 86 via a washer 84 to the left end face of the crankshaft 20, and are integrated with the crankshaft 20. Therefore, the fixed drive pulley half 64a and the inner boss 80 are each fixed integrally with the crankshaft 20 and rotate integrally with the crankshaft 20. At least one of the sleeve 78 and the sleeve 82 may be formed integrally with the inner boss 80.

[0041] On the other hand, the movable driving pulley half 64b facing the fixed driving pulley half 64a on the right side is integrally provided on a cylindrical outer boss 88 which serves as its base. The outer boss 88 is disposed so that its inner peripheral surface 88i is in slidable contact with the outer peripheral surfaces of the sleeve 78 and the sleeve 82 and can move in the axial direction relative to the inner boss 80. A ball member 150 is provided on the outer boss 88, and the ball member 150 can roll on the outer peripheral surface 80a of the inner boss 80. As described later, the rolling surface of the ball member 150 of the inner boss 80 extends spirally around the axis of the inner boss 80, i.e., the axis 20A of the crankshaft 20, so that the outer boss 88 can rotate relative to the inner boss 80 within a predetermined range and can also move in the axial direction in conjunction with the rotation. The relative rotation of the outer boss 88 with respect to the inner boss 80 is restricted within a predetermined range so as to convert the rotational motion of the crankshaft 20 into the axial motion of the crankshaft 20. Therefore, when an axial driving force is applied by the variable speed drive mechanism D described later and the movable drive pulley half 64b approaches or moves away from the fixed drive pulley half 64a, the outer boss 88 with which the movable drive pulley half 64b is integrally formed rotates essentially around the crankshaft 20 while at the same time moving in the axial direction.

[0042] In this manner, the right movable drive pulley half 64b facing the left fixed drive pulley half 64a can rotate about the crankshaft 20 and move axially toward or away from the fixed drive pulley half 64a. A V-belt 90 is sandwiched and wound between the opposing tapered surfaces of both drive pulley halves 64a, 64b.

[0043] A driven pulley 94, which is rotatably supported on a driven shaft 92, which is the input shaft of the reduction gear mechanism Tr, behind the drive pulley 64, comprises a fixed driven pulley half 94a and a movable driven pulley half 94b, which faces the fixed driven pulley half 94a on the left side and is axially slidable.

[0044] An inner sleeve 96 is supported on the driven shaft 92 via a bearing so as to be freely rotatable relative to the driven shaft 92 while its axial movement is restricted, and a fixed driven pulley half 94a is integrally secured to the right end flange portion of the inner sleeve 96 by welding its center hole.

[0045] An outer sleeve 98 is fitted onto the outer periphery of the inner sleeve 96 of the fixed driven pulley half 94a, and a guide pin protruding from the inner sleeve 96 is fitted into a long hole formed in the outer sleeve 98 in the axial direction, allowing the outer sleeve 98 to move axially relative to the inner sleeve 96, but relative rotation is restricted.

[0046] The movable driven pulley half 94b is integrally fixed to the right end flange portion of the outer sleeve 98 by welding its center hole. Therefore, the movable driven pulley half 94b rotates together with the fixed driven pulley half 94a, but can also move axially toward and away from the fixed driven pulley half 94a.

[0047] A clutch inner 102 of a centrifugal clutch 100 is fixed to the left end of the inner sleeve 96 with a nut, and a coil spring 101 is interposed between the clutch inner 102 and the movable driven pulley half 94b, so that the coil spring 101 urges the movable driven pulley half 94b to the right.

[0048] In the belt-type continuously variable transmission 10, power is transmitted by a V-belt 90 stretched between the drive pulley 64 and the driven pulley 94. In the belt-type continuously variable transmission 10, the speed change drive mechanism D operates in response to the engine rotation speed, whereby the movable drive pulley half 64b moves relative to the fixed drive pulley half 64a, changing the winding diameter of the V-belt 90 around the drive pulley 64, and simultaneously changing the winding diameter around the driven pulley 94 accordingly, automatically changing the gear ratio and achieving continuously variable speed change.

[0049] The centrifugal clutch 100 comprises a cup-shaped clutch outer 104 covering the outer periphery of a clutch inner 102, the base of which is fixed to the left end of the driven shaft 92 by a nut 106. A clutch shoe 112 is biased by a spring 108 onto the clutch inner 102 and supported on a support shaft 110 so as to be able to swing freely. The clutch shoe 112 is disposed opposite the inner periphery of the clutch outer 104.

[0050] The clutch inner 102 of the centrifugal clutch 100 rotates integrally with the infinitely variable driven pulley 94 of the belt-type continuously variable transmission 10. Therefore, when the rotational speed exceeds a predetermined rotational speed, the clutch shoe 112 of the clutch inner 102 swings against the spring 108 due to centrifugal force and comes into contact with the inner surface of the clutch outer 104, causing the clutch outer 104 to rotate integrally with the clutch outer 104, thereby transmitting power to the driven shaft 92.

[0051] The driven shaft 92 is supported by the transmission case 12 and the transmission case cover 16 via bearings 113, 114, and its right end inserted into the reduction gear chamber 52 on the rear right side of the transmission case 12 is supported by the reduction gear cover 116 via a bearing 117.

[0052] In the reduction gear mechanism Tr in the reduction gear chamber 52, a reduction intermediate shaft 118 is supported between the driven shaft 92 and the rear axle 36, oriented parallel to each other (horizontally in the left-right direction), and supported by the transmission case 12 and the reduction gear cover 116, and the gears of each shaft constitute the reduction gear mechanism Tr. Therefore, the rotation of the driven shaft 92 is reduced in speed via the reduction gear mechanism Tr and transmitted to the rear axle 36, causing the rear wheels Wr, which are driving wheels, to rotate. In this way, the centrifugal clutch 100, which rotates integrally with the driven pulley 94, is engaged when the rotation speed exceeds a predetermined rotation speed, and transmits the driving force of the power source, here the internal combustion engine E, to the rear wheels Wr, which are driving wheels of the vehicle.

[0053] When the belt-type continuously variable transmission 10 is operating in conjunction with the operation of the internal combustion engine E, the cooling fan 64f formed integrally on the left side of the fixed drive pulley half 64a also rotates together with the fixed drive pulley half 64a. As a result, outside air taken in from an outside air intake 18a (see Figs. 1 and 2) provided in the outer cover 18 facing the side of the vehicle is introduced into the belt chamber 14 inside the transmission case cover 16 through the cooling air inlet of the transmission case cover 16. The flow of cooling air inside the belt chamber 14 is shown diagrammatically by arrows in Fig. 2.

[0054] As described above, in the belt-type continuously variable transmission 10, the V-belt 90 is stretched between the drive pulley 64 and the driven pulley 94 to transmit power. In the belt-type continuously variable transmission 10, the speed change drive mechanism D operates in response to the engine rotation speed to move the movable drive pulley half 64b in the axial direction relative to the fixed drive pulley half 64a, changing the winding diameter of the V-belt 90 around the drive pulley 64, and the winding diameter around the driven pulley 94 changes accordingly, automatically changing the speed ratio and continuously changing the speed. Here, the speed change drive mechanism D will be described in detail mainly with reference to Figs. 3 to 6. The speed change drive mechanism D corresponds to the drive mechanism in the present invention, and includes a motor, i.e., a speed change drive motor 120. The speed change drive mechanism D is configured to generate a driving force in the axial direction of the movable drive pulley half 64b in the drive pulley 64 so as to move the movable drive pulley half 64b relative to the fixed drive pulley half 64a. The axial direction of the movable driving pulley half 64 b is the axial direction of the driving pulley 64 , which coincides with the axial direction of the crankshaft 20 .

[0055] The speed change drive mechanism D is positioned on the front left side of the front part 12a of the transmission case 12. The speed change drive mechanism D is provided in a unit case 122 together with the cam assist mechanism C. The motor 120 of the speed change drive mechanism D is housed in the unit case 122, and a reduction mechanism 124 of the speed change drive mechanism D is attached to the unit case 122. The unit case 122 is divided into left and right halves, and is composed of a right case 122a facing the front part 12a of the transmission case 12 on the left side, and a left case 122b fixed to the right case 122a by a bolt 123. The motor 120, the reduction mechanism 124, and the axial feed mechanism M are arranged in this order from the radial outside around the crankshaft 20. The cam assist mechanism C is arranged radially inside the axial feed mechanism M.

[0056] The unit case 122 is shaped so that the left extension is inserted therethrough from the step 76 which changes to a smaller diameter on the left side of the main bearing 55 on the left side of the crankshaft 20, and the right case 122a is formed with a through hole (hereinafter, shaft through hole) 122i through which the crankshaft 20 is inserted, and the left case 122b is also formed with a through hole (hereinafter, shaft through hole) 122h through which the crankshaft 20 is inserted.

[0057] The motor 120 is positioned on the vehicle front FR side in the transmission drive mechanism D. The motor 120 is disposed in the left case 122b so that the drive shaft 120a of the motor 120 is parallel to the crankshaft 20, and a drive gear 120b is formed on the drive shaft 120a of the motor 120. Both ends of a first reduction gear shaft 130s are journalled via bearings 126, 128 in the bearing recesses 122c and 122d facing each other on the inside of the unit case 122, and a large diameter gear 130a integral with the first reduction gear shaft 130s meshes with the drive gear 120b of the drive shaft 120a of the motor 120. The first reduction gear shaft 130s is disposed parallel to the drive shaft 120a of the motor 120. The first reduction gear shaft 130s is also provided with a small diameter gear 130b that is integral with the first reduction gear shaft 130s and is aligned with the large diameter gear 130a in the axial direction. The first reduction gear 130 in the reduction mechanism 124 is configured with the first reduction gear shaft 130s, the large diameter gear 130a, and the small diameter gear 130b.

[0058] The reduction mechanism 124 includes a second reduction gear 132 in addition to the first reduction gear 130. The second reduction gear 132 includes a large-diameter gear 132a that meshes with a small-diameter gear 130b of the first reduction gear shaft 130s. The large-diameter gear 132a includes a cylindrical portion 132b that extends from the large-diameter gear 132a to one side, i.e., to the right side in Figs. 3 to 5, along the central axis of the large-diameter gear 132a. A gear shaft portion 134a on the right end side of the screw member 134 is press-fitted into the cylindrical portion 132b along the axis of the second reduction gear 132, i.e., the large-diameter gear 132a. Therefore, the large-diameter gear 132a is fixed integrally to the screw member 134.

[0059] The cylindrical portion 132b into which the gear shaft portion 134a is press-fitted so as to penetrate the center is disposed in a state in which it is inserted into an axial through-hole 122e of the right case 122a of the unit case 122. At this time, two bearings 136, 138 are provided on the outer periphery of the cylindrical portion 132b of the second reduction gear 132 so as to sandwich the right case 122a between the two bearings 136, 138. Note that in the right case 122a, the through-hole 122e is positioned radially outward of the shaft through-hole 122i.

[0060] A bearing 136, which is a rolling bearing, is provided between the tip of the cylindrical portion 132b of the second reduction gear 132, i.e., the outer end of the right case 122a, and a step portion 122f near the through hole 122e of the right case 122a. The bearing 136 is configured to be able to receive radial loads. More specifically, the bearing 136 is configured to be able to receive not only radial loads but also axial loads. A collar 133, which is a cylindrical member, is provided to continue from the tip of the cylindrical portion 132b of the second reduction gear 132, and the tip side of the gear shaft portion 134a of the screw member 134 is inserted into the collar 133, and the bearing 136 is provided on the radial outside of the cylindrical portion 132b and the collar 133. As shown in Figs. 3 to 5, a nut 140 is screwed onto the male threaded portion 134b at the tip of the gear shaft portion 134a of the screw member 134 and tightened, so that the bearing 136 is fixed between the nut 140 and the hole wall portion 122g that defines the through hole 122e of the right case 122a. Meanwhile, a bearing 138, which is a large diameter needle bearing, is provided at the base end of the cylindrical portion 132b of the second reduction gear 132, that is, at the left end portion near the large diameter gear 132a. The bearing 138 is a thrust roller bearing here, and is configured to be able to receive an axial load. The bearing 138 is provided so as to be sandwiched between the large diameter gear 132a and the hole wall portion 122g that defines the through hole 122e of the right case 122a in the axial direction and in contact with them. The second reduction gear 132, provided with the bearings 136, 138 in this manner, is attached to the right case 122a so that it can rotate relative to the right case 122a but cannot move axially by screwing a nut 140 onto the male threaded portion 134b at the tip of the gear shaft portion 134a which is press-fitted into the second reduction gear 132 and tightening the nut 140.

[0061] The screw member 134, which is attached to the right case 122a so as to be rotatable relative to the right case 122a but immovable in the axial direction, has, in order from the right in Figs. 3 to 5, the male screw portion 134b, the gear shaft portion 134a, the flange portion 134c, and the male screw portion 134d, which are arranged in the axial direction of the screw member 134. The second reduction gear 132, i.e., the large diameter gear 132a, abuts against the flange portion 134c on its left side. Therefore, the screw member 134 is held by the bearings 136 and 138 with the right case 122a sandwiched between the bearings 136 and 138. Therefore, for example, when a radial load is generated by a force acting on the screw member 134, or when an axial load is generated in the left direction, the load can be received by the bearing 136, and when a force is acting on the screw member 134 and an axial load is generated in the right direction, the load can be received by the bearing 138. Furthermore, since the screw member 134 uses the nut 140 and the flange portion 134c to prevent the bearings 136, 138 from coming loose, the allowable axial load, i.e., the allowable thrust load, can be improved, and the screw member 134 can be made more resistant to coming loose.

[0062] The speed change drive mechanism D further includes a movable holder 142 that is movable in the axial direction. Fig. 6 shows a plan view of the movable holder 142 as viewed from the left side in Figs. 3 to 5. The movable holder 142 is donut-shaped and includes a through hole 142a that extends in the axial direction at its center. The crankshaft 20 and the cam assist mechanism C provided around the crankshaft 20 are disposed in the through hole 142a. A bearing 144 that is a rolling bearing is held by a bearing holding portion 88c that is a holding portion on the outer periphery of the outer boss 88 of the cam assist mechanism C and a holding portion 142b that is provided in a wall portion that defines the through hole 142a of the movable holder 142, and the movable holder 142 is supported by the bearing 144 so as to be rotatable relative to the crankshaft 20. The movable holder 142 is disposed in the shaft through hole 122h of the left case 122b of the unit case 122, and is sealed by sandwiching an X-ring 146, which is a sealing member, between an outer circumferential surface 142c of the movable holder 142 and the shaft through hole 122h of the left case 122b of the unit case 122. An O-ring, an oil seal, or the like may also be used as the sealing member.

[0063] The male screw portion 134d on the left side of the flange portion 134c of the screw member 134 is screwed into a female screw hole 142d, which is a female screw portion of the movable holder 142. The screw member 134 and the movable holder 142 constitute an axial feed mechanism (axial feed mechanism) M. The male screw portion 134d is a trapezoidal screw, so it is suitable for transmitting motion. In the movable holder 142, the female screw hole 142d is provided radially outside the through hole 142a and radially inside the outer circumferential surface 142c. The male screw portion 134d of the screw member 134 enters and screwed into the female screw hole 142d from the right side. The left end of the female screw hole 142d is sealed with a cap member 148.

[0064] Therefore, in the variable speed drive mechanism D, when the variable speed drive motor 120 is driven and the drive gear 120b formed on the drive shaft 120a rotates, the large diameter gear 130a of the first reduction gear shaft 130s meshing with the drive gear 120b rotates at a reduced speed together with the small diameter gear 130b, and the large diameter gear 132a meshing with this small diameter gear 130b rotates and further decelerates and rotates together with the male threaded portion 134d of the screw member 134, which has a smaller diameter than the large diameter gear 132a, and the rotation of the male threaded portion 134d causes the meshing between the male threaded portion 134d and the female threaded hole 142d of the movable holder 142 to shift axially, thereby moving the movable holder 142 axially. In this way, the movable holder 142 moves axially by driving the speed change drive motor 120 in the forward and reverse directions, whereby the outer boss 88 of the cam assist mechanism C described above moves relative to the inner boss 80, and as shown by the solid and dashed lines in Figure 3 and as shown in Figures 4 and 5, the movable drive pulley half 64b can approach or move away from the fixed drive pulley half 64a, thereby changing the winding diameter of the V-belt 90 wound between the opposing tapered surfaces of the two drive pulley halves 64a, 64b, thereby performing infinitely variable speed change.

[0065] The reduction gear mechanism 124 has an arrangement configuration having three shafts: the drive shaft 120a of the motor 120, the first reduction gear shaft 130s of the first reduction gear 130, and the gear shaft portion 134a of the second reduction gear 132. Therefore, the diameter of each gear can be made small, and as a result, the radial protrusion of the reduction gear mechanism 124 from the crankshaft 20 can be reduced.

[0066] Here, the cam assist mechanism C will be further described. As described above, the cam assist mechanism C is of a ball cam type, and includes the inner boss 80, the outer boss 88, and the ball member 150 provided thereon. As described above, the sleeve 78, the inner boss 80, the sleeve 82, and the fixed drive pulley half 64a are fitted from the right to the left extension from the step portion 76 of the crankshaft 20 in this order. The inner boss 80 is integral with the crankshaft 20, rotates together with the crankshaft 20, and is immovable in the axial direction relative to the crankshaft 20. On the other hand, the outer boss 88 is disposed so as to be slidable along the outer peripheral surface 80a of the inner boss 80, and the movable drive pulley half 64b provided on the outer boss 88 substantially rotates together with the outer boss 88 around the crankshaft 20 when the outer boss 88 slides against the inner boss 80, and at the same time moves in the axial direction. The ball member 150 is provided so as to cause the axial movement due to the rotation of the outer boss 88. That is, the cam assist mechanism C includes an inner boss 80 which is an inner member provided so as to be rotatable integrally with the crankshaft 20 of the internal combustion engine E which is the output shaft of the power source, an outer boss 88 which is an outer member which is axially movable along the outer circumferential surface of the inner boss 80 together with the movable driving pulley half 64b, and a ball member 150 which causes the rotation and axial movement of the outer boss 88 relative to the inner boss 80. Note that the number of ball members 150 is four here, but may be at least one.

[0067] FIG. 7 shows a perspective view of the inner boss 80. FIG. 7 shows the inner boss 80 as seen from the internal combustion engine E side in FIG. 3. In FIG. 7, the directional arrows RH and LH in FIG. 3 are also added. The inner boss 80 is cylindrical, and the rolling surfaces 80f of the ball members 150 are formed on its outer circumferential surface 80a. Since four ball members 150 are used here, the same number of grooves 80b as the number of ball members 150, that is, four grooves 80b serving as the rolling surfaces 80f, are formed on the outer circumferential surface 80a of the inner boss 80. Each groove 80b has an arc-shaped cross section and extends spirally around the axis of the inner boss 80. In the arrangement of the inner boss 80 shown in FIGS. 3 to 5 and 7, the spiral shape of the rolling surfaces 80f, i.e., the grooves 80b, is determined so that it twists in a direction against the rotation direction R of the crankshaft 20 toward the left side in the axial direction, i.e., the fixed drive pulley half 64a side. The radius of curvature of the rolling surface 80f of each groove portion 80b is larger than the radius of curvature of the ball member 150, which is a sphere, by 0.1 mm to 0.7 mm.

[0068] FIG. 8 shows the arrangement of ball members 150 corresponding to each groove portion 80b. The ball members 150, which are arranged so as to be able to run in the groove portion 80b of the inner boss 80, are provided in holes 88a of the outer boss 88. FIG. 9 shows the arrangement of the outer boss 88 on the outer side of the inner boss 80 in FIG. 8, and FIG. 10 shows a cross-sectional view at a position passing through the center of the ball members 150, i.e., a cross-sectional view taken along line XX in FIG. 9. FIG. 11 shows a perspective view of the outer boss 88, and the directional arrows RH and LH in FIG. 3 are also added in FIG. 11. However, in FIGS. 9 and 10, only a portion of the outer boss 88 is shown cut out. When the cam assist mechanism C is provided on the crankshaft 20 as shown in Figures 3 to 5, the axis 20A of the crankshaft 20 coincides with the axis of the inner boss 80 and also coincides with the axis of the outer boss 88. Therefore, in Figures 7 to 11, the axis 20A of the crankshaft 20 is shown as the axis of the inner boss 80 or the outer boss 88.

[0069] The outer boss 88 is cylindrical and includes, from the right side in Figs. 3 to 5 and 11, a tip portion 88b, an intermediate portion 88m including a bearing holding portion 88c, and a pulley mounting portion 88d. The tip portion 88b has the smallest diameter, and the diameter increases in the order of the intermediate portion 88m and the pulley mounting portion 88d. The bearing holding portion 88c has a step portion 88e for holding a bearing, and has an annular groove portion 88f on the right side into which a stopper for holding a bearing is fitted. The movable driving pulley half 64b is fixed to the pulley mounting portion 88d so as to sandwich a flange portion 88g of the pulley mounting portion 88d (see Figs. 4 and 5). The movable driving pulley half 64b is attached to the pulley mounting portion 88d by casting, but may be attached by various joining means such as welding or mechanical joining means.

[0070] The outer boss 88 is provided with four holes 88a extending in the radial direction. The four holes 88a are through holes provided in the bearing holding portion 88c of the outer boss 88. The four holes 88a are formed at the same location in the axial direction and are arranged at 90° intervals in the circumferential direction. The outer peripheral ends of the four holes 88a are closed by the inner race 144a of the bearing 144 described above provided between the drive mechanism D and the cam assist mechanism C. That is, the hole 88a is closed by defining the bottom on the radially outer side by the inner race 144a of the bearing 144, and opens only on the inner boss 80 side. However, the bottom of the hole 88a is not limited to being closed by the inner race 144a, and may be closed by the outer boss 88 itself, for example. The bearing 144 includes an inner race 144a, an outer race 144b, and a plurality of balls 144c between them.

[0071] 4 and 5, a disc spring 152, which is an elastic member, is disposed between the inner race 144a of the bearing 144 and the ball member 150 in the hole 88a. This disc spring presses the ball member 150 toward the inner boss 80, thereby enabling the ball member 150 to roll more suitably along the groove 80b of the inner boss 80, which serves as the rolling surface 80f. Note that the elastic member is not limited to the disc spring 152, and instead of the disc spring 152, for example, a wave washer may be used.

[0072] 12 is an enlarged cross-sectional view of one hole 88a of the outer boss 88 in the cam assist mechanism C. FIG. 12 is a cross-sectional view taken along a virtual plane perpendicular to the axis 20A of the crankshaft 20.

[0073] When the cam assist mechanism C rotates together with the crankshaft 20 in the rotation direction R shown in Figures 7, 9, 10, and 12, if the crankshaft 20 rotates faster than before, the rotation of the outer boss 88 is likely to be delayed relative to the inner boss 80. As a result, a force is applied to the ball member 150 from the inner boss 80, and for example, a force F as shown in Figure 12 is applied from the edge portion 80c of the groove portion 80b of the inner boss 80. The force F can be divided into a normal load F1, a tangential load F2 perpendicular to the normal load F1, and a circumferential force F3. The circumferential force F3 is applied from the ball member 150 to the outer boss 88, and the reaction force of the circumferential force F3 encourages the ball member 150 to move along the rolling surface 80f of the groove portion 80b of the inner boss 80, thereby encouraging the outer boss 88 to move together with the ball member 150. 7 and 8, because the groove 80b of the inner boss 80 is spiral as described above, the direction of this movement is opposite to the rotational direction R and is also in the axial direction, in this case, toward the left in the axial direction. Note that this left axial direction is toward the fixed drive pulley half 64a.

[0074] On the other hand, when the rotation of the crankshaft 20 becomes faster than before, the control device, i.e., the ECU 170 described later, controls the operation of the motor 120 so that the movable driving pulley half 64b approaches the fixed driving pulley half 64a based on an input from a sensor that detects the rotation of the crankshaft 20, i.e., a crank angle sensor, which will be described later. This movement of the movable driving pulley half 64b relative to the fixed driving pulley half 64a coincides with the above-mentioned axial direction in which the movement of the outer boss 88 relative to the inner boss 80 is promoted. Therefore, the cam assist mechanism C acts to assist the axial movement of the movable driving pulley half 64b relative to the fixed driving pulley half 64a by the motor 120. In other words, the cam assist mechanism C can assist the axial movement of the movable driving pulley half 64b, which is integral with the outer boss 88, by the rotational movement of the crankshaft 20.

[0075] This also occurs in the opposite direction when the rotation of the crankshaft 20 becomes slower than before. When the cam assist mechanism C rotates together with the crankshaft 20 in the rotation direction R, if the rotation of the crankshaft 20 becomes slower than before, the rotation of the inner boss 80 is likely to be delayed relative to the outer boss 88. As a result, a force is applied to the ball member 150 from the inner boss 80, and the ball member 150 is encouraged to move along the rolling surface 80f of the groove portion 80b of the inner boss 80, which encourages the outer boss 88 to move together with the ball member 150. The direction of movement at this time is the direction of the rotation direction R and the axial direction, here the direction to the right in the axial direction, as is clear from Figures 7 and 8, since the groove portion 80b of the inner boss 80 is spiral as described above. Note that this axial right direction is the direction away from the fixed drive pulley half 64a. When the rotation of the crankshaft 20 becomes slower than before in this manner, the ECU 170 controls the operation of the motor 120 to move the movable driving pulley half 64b away from the fixed driving pulley half 64a based on an input from a sensor that detects the rotation of the crankshaft 20, i.e., the engine rotation speed sensor 176. This movement of the movable driving pulley half 64b relative to the fixed driving pulley half 64a coincides with the above-mentioned axial direction in which the movement of the outer boss 88 relative to the inner boss 80 is urged, and therefore the cam assist mechanism C acts to assist the axial movement of the movable driving pulley half 64b relative to the fixed driving pulley half 64a by the motor 120.

[0076] Therefore, the output of the variable speed drive mechanism D that moves the movable drive pulley half 64b can be reduced compared to when the cam assist mechanism C is not provided. In other words, the movable drive pulley half 64b can be moved with less output from the motor 120. This allows the motor 120 of the variable speed drive mechanism D to be made smaller.

[0077] In order to more suitably generate such an assist in the cam assist mechanism C, it is preferable to set the radial thickness 88t of the outer boss 88 to be equal to or greater than the radius of the ball member 150, and to provide the ball member 150 in the hole 88a with as few gaps as possible. Also, the radius of curvature of the rolling surface 80f of each groove 80b is made larger than the radius of curvature of the ball member 150 by 0.1 mm to 0.7 mm, but by reducing the outer diameter of the inner boss 80, that is, by thinning the radial thickness 80t, and setting the depth 80d of the groove 80b of the inner boss 80 to within a range of 20% to 45% of the diameter of the ball member 150, for example, the normal load F1 can be reduced and the clearance between the ball member 150 and the rolling surface 80f can be suppressed, thereby improving the toughness against the generation of hitting sounds.

[0078] In addition, since the cam assist mechanism C is of the ball cam type, the assist capacity, i.e., the assist thrust, can be easily adjusted by changing the number of ball members 150 or the angle of the rolling surface. FIG. 13 simply shows the relationship between the groove 80b and the axis 20A in the inner boss 80 as viewed by arrow XIII in FIG. 7. In FIG. 13, the direction of the groove 80b, i.e., the rolling surface 80f, is shown diagrammatically by a line. In FIG. 13, the inclination angle θ of the groove 80b with respect to the axis 20A corresponds to the rolling surface angle. By changing the angle θ of this rolling surface, the assist capacity can be changed.

[0079] Here, Fig. 14 shows a cross-sectional view of the right case 122a of the unit case 122 and its surroundings as seen from the front of the vehicle, and Fig. 15 shows a cross-sectional view from behind it. Fig. 16 shows a view of the left side of the right case 122a of the unit case 122 as seen from the direction of the axis 20A. As shown in Figs. 14 and 15, a plurality of stopper portions 122s are spaced apart in the circumferential direction on the inner surface of the right case 122a. Here, four stopper portions 122s are arranged at 90° intervals (see Fig. 16). However, the number of stopper portions 122s is not limited to four, and it is preferable that there be at least one.

[0080] As shown in Figs. 14 and 15, the right case 122a of the unit case 122 is provided with an extension pipe 154 extending axially outward, i.e., to the right, toward the front part 12a of the transmission case 12. The extension pipe 154 is provided so that a hole 154h that communicates the inside and outside of the unit case 122 extends to the outside of the case 122. As shown in Fig. 16, the extension pipe 154 is positioned at the upper part of the right case 122a in the vertical direction in the motorcycle 1 of Fig. 1. This allows air to flow in and out of the unit case 122 and the power unit P in a suitable manner, and reduces the pumping load of the motor 120 when the volume of the unit case 122 increases or decreases due to a gear shift, and suppresses condensation in the unit case 122. The air flow in and out of the unit case 122 also allows the gear shift drive mechanism D and other components to be cooled in a suitable manner.

[0081] A cover portion 156 is provided on the inner surface of the front portion 12a of the transmission case 12 so as to hang down from above to below and partially cover the outer inlet 154a of the extension pipe portion 154 to prevent water, oil, etc. from entering the unit case 122 through the extension pipe portion 154. The cover portion 156 is plate-shaped, but is formed so as to be curved along the extension pipe portion 154. In the belt chamber 14 in the transmission case cover 16, as shown in FIG. 2, the cooling air flows from the lower portion to the rear in the vertical direction around the crankshaft 20, then flows vertically upward, and also flows in the same direction along the V-belt 90. Therefore, the cover portion 156 is positioned behind the outer inlet 154a of the extension pipe portion 154. Therefore, when the cooling air approaches the outer inlet 154a of the extension pipe portion 154, its flow is obstructed by the cover portion 156 and the air passes through a labyrinth-like flow path formed around the cover portion 156, thereby preventing the active intrusion of fluids such as water and oil from the outer inlet 154a of the extension pipe portion 154.

[0082] In addition, a drain tube 160, which is a member for draining water, is provided in a hole, i.e., a drain hole 160h, formed in the lower part of the vertical direction of the unit case 122. In particular, a hole 160h that connects the inside and outside of the unit case 122 is formed in the lowest part of the unit case 122, and the drain tube 160 is provided in the hole 160h. As shown in the cross-sectional view of FIG. 17, the hole 160h is formed in the mating surface between the right case 122a and the left case 122b of the unit case 122, forming a labyrinth structure 160L. The drain tube 160 is made of resin, and the base end 160a is substantially cylindrical and the tip end 160b is flattened. In other words, the drain tube 160 functions as a member for draining water that allows water to flow out of the unit case 122 but prevents water from flowing into the unit case 122 through the drain tube 160. Therefore, even if water gets into the unit case 122, the volume change inside the unit case 122 accompanying the gear shift will cause the water to flow out of the unit case 122 through the drain tube 160, but it will not flow back in through the tip 160b of the drain tube 160.

[0083] The speed change drive mechanism D and the cam assist mechanism C integrated with the unit case 122 configured as described above are formed with dimensions such that the hole of the inner boss 80 and the like fit exactly onto the crankshaft 20, and are attached as follows. First, the left end of the crankshaft 20 is inserted into the shaft through hole 122i of the right case 122a of the unit case 122, and then, while rotating the screw member 134 into the female thread portion 142d of the movable holder 142, the crankshaft 20 is further inserted, whereby the speed change drive mechanism D and the cam assist mechanism C integrated with the unit case 122 are attached to the front part 12a of the transmission case 12. Then, the unit case 122 is fixed to the transmission case 12 with the bolt 158. In this way, the speed change drive mechanism D and the cam assist mechanism C have excellent mountability. In addition, the wall portion that defines the shaft through hole 122i of the right case 122a is fitted, via a seal member, into the outer peripheral surface of a cylindrical portion 12c that extends axially to the left at the front portion 12a of the transmission case 12 that extends around the crankshaft 20.

[0084] According to the belt type continuously variable transmission 10 described above, the speed change drive mechanism D of the belt type continuously variable transmission 10 includes the screw member 134 that is rotated by the rotation of the motor 120, extends in the axial direction, and is not movable in the axial direction (is not movable in the axial direction), and the movable holder 142 that has the female thread portion 142d that screws with the screw member 134 and is movable in the axial direction together with the movable drive pulley half 64b. With this configuration, the movable holder 142 can be directly driven by the screw member 134, and the drive position at which the movable holder 142 is driven by the screw member 134 can be brought closer to the load position on the belt 90 in the drive pulley 64 (for example, the position of the V-belt 90 shown in Figures 4 and 5) in the radial direction centered on the crankshaft 20. Therefore, it is possible to suppress the inclination of the movable drive pulley half 64b, and to reduce the radial size of the speed change drive mechanism D, thereby enabling the belt type continuously variable transmission 10 to be made more compact. Therefore, the degree of freedom in designing the belt-type continuously variable transmission 10 can be increased.

[0085] In particular, the screw member 134 is positioned closer to the crankshaft 20 than the outer circumferential portion 64o of the movable driving pulley half 64b (see Figs. 3 to 5). This makes it possible to more suitably suppress the inclination of the movable driving pulley half 64b and reduce the radial size of the speed change driving mechanism D. Note that the outer circumferential portion 64o of the movable driving pulley half 64b is, for example, the outer circumferential surface of the movable driving pulley half 64b.

[0086] The speed change drive mechanism D is provided with a unit case 122 that houses the motor 120 and is provided with a reduction mechanism 124 to which the driving force of the motor 120 is transmitted, and is provided therein. The screw member 134 is provided in a state in which it is inserted into a wall portion (case wall portion) 122g of the case 122 that extends in the radial direction of the unit case 122. A bearing 136 as a first bearing and a bearing 138 as a second bearing are provided around the screw member 134 so as to sandwich the wall portion 122g. The bearing 136 is a rolling bearing and is configured to be able to receive radial loads and axial loads, and the bearing 138 is a thrust roller bearing and is configured to be able to receive axial loads. Therefore, the radial load and axial load generated in the screw member 134 can be firmly received. Therefore, the belt-type continuously variable transmission 10 can be made smaller and lighter by thinning the unit case 122 and the like.

[0087] The screw member 134 has a flange portion 134c extending in the radial direction, and the bearings 136, 138 are sandwiched between the flange portion 134c on the movable driving pulley half 64b side of the wall portion 122g of the unit case 122 and a nut 140, which is a fastening member that is located on the opposite side of the wall portion 122g to the flange portion 134c and is screwed into the screw member 134. This configuration can improve the pull-out toughness of the screw member 134.

[0088] Furthermore, in the speed change drive mechanism D, the outer peripheral surface 142c of the movable holder 142 serves as a sealing surface between the left case 122b of the unit case 122, and a cap member 148 is provided on the movable drive pulley half 64b side of the female thread portion 142d. With this configuration, compared to a case in which a sealing member is provided on the screw shaft, i.e., the axis of the screw member 134, it is possible to shorten the axial extension amount of the belt type continuously variable transmission 10 and also reduce the protrusion amount of the entire unit including the speed change drive mechanism D.

[0089] Also, a hole 154h that communicates between the inside and outside of the unit case 122 is formed in the vertical upper part of the unit case 122. This makes it possible to take in air into the case 122 while suitably preventing the intrusion of water, etc. into the inside of the unit case 122. Note that the hole 154h is provided at a position in the axial direction farther from the movable drive pulley half 64b than the movable holder, that is, in this case, it is provided on the back side of the unit case 122. In this way, the hole 154h is provided in the unit case 122 on the internal combustion engine E side. This makes it possible to prevent dust and water from intruding into the unit case 122 through the hole 154h.

[0090] Then, the extension pipe portion 154 is provided so as to extend the hole 154h to the outside of the unit case 122, and further, a cover portion 156 is provided so as to partially cover the outer inlet 154a of the extension pipe portion 154. Therefore, a labyrinth-shaped flow path can be formed around the cover portion 156 that partially covers the outer inlet 154a of the extension pipe portion 154, and therefore, it is possible to actively prevent fluids such as water and oil from entering the unit case 122 from the outer inlet 154a of the extension pipe portion 154.

[0091] A drain hole 160h is formed in the lower vertical portion of the unit case 122, and a drain tube 160 is provided in the drain hole 160h as a water draining member. The drain tube 160 has the above-mentioned configuration. Therefore, even if water gets into the unit case 122, the drainage performance of the unit case 122 can be ensured.

[0092] Furthermore, the belt type continuously variable transmission 10 is provided with a cam assist mechanism C that converts the rotational motion of the crankshaft into the axial motion of the crankshaft 20 so as to assist the axial movement of the movable driving pulley half body 64b by the speed change drive mechanism D. This makes it possible to suitably assist the axial movement of the movable driving pulley half body 64b by the speed change drive mechanism D.

[0093] The cam assist mechanism C is of a ball cam type and includes an inner boss 80 provided so as to be rotatable integrally with the crankshaft 20, an outer boss 88 that is axially movable along the outer circumferential surface 80a of the inner boss 80 together with the movable driving pulley half 64b, and at least one ball member provided so as to be involved with the inner boss 80 and the outer boss 88. With this configuration, the rotational motion of the crankshaft 20 can be suitably converted into axial motion of the crankshaft 20.

[0094] The rolling surface 80f of the ball member 150 is formed on the outer peripheral surface 80a of the inner boss 80, and the ball member 150 is disposed in the hole 88a, particularly in this case, the through hole, of the outer boss 88. This makes it possible to reduce the number of components of the cam assist mechanism C, and also makes it possible to manufacture or process the cam assist mechanism C at low cost.

[0095] The bottom of hole 88a is defined by an inner race 144a of a bearing 144 held by a holding portion of the speed change drive mechanism D and a holding portion of the assist mechanism C. With this configuration, an increase in the number of parts in the cam assist mechanism C can be suppressed, and also, the formation of hole 88a in the outer boss 88 can be made easier.

[0096] Also, the disc spring 152 is provided as a pressing member, i.e., an elastic member, as described above so as to press the ball member 150 against the inner boss 80 (see Figs. 4, 5 and 12). Therefore, the radial gap between the ball member 150 and the inner boss 80 can be reduced, and thus hitting noises due to the collision of the ball member 150 with the inner boss 80, etc. can be suppressed.

[0097] Furthermore, the cam assist mechanism C is disposed between the variable speed drive mechanism D and the movable drive pulley half body 64b. Therefore, the cam assist mechanism C can more suitably assist the transmission of the driving force from the variable speed drive mechanism D to the movable drive pulley half body 64b.

[0098] When the movable driving pulley half 64b is moved away from the fixed driving pulley half 64a, a stopper portion 122s for restricting the axial movement of the movable driving pulley half 64b to the right is provided on the inner surface of the right case 122a of the unit case 122. The movable holder 142 is formed so that the axial protrusion 142p on the outer periphery of the movable holder 142 can abut against the stopper portion 122s (see FIG. 4). On the other hand, when the movable driving pulley half 64b is moved closer to the fixed driving pulley half 64a, the left axial end portion 64e of the face surface of the movable driving pulley half 64b can abut against the right axial end portion 64d of the face surface of the fixed driving pulley half 64a so as to restrict the axial movement of the movable driving pulley half 64b to the left (see FIG. 5).

[0099] In the belt-type continuously variable transmission 10 of the above embodiment, the motor 120 of the speed change drive mechanism D is driven forward and backward to move the movable holder 142 in the axial direction, so that the outer boss 88 of the cam assist mechanism C moves relative to the inner boss 80, and the movable drive pulley half 64b can approach or move away from the fixed drive pulley half 64a, as shown by solid and broken lines in Fig. 3 and as shown in Figs. 4 and 5, and thus the winding diameter of the V-belt 90 wound around the opposing tapered surfaces of both drive pulley halves 64a, 64b is changed, thereby performing continuously variable speed change. The control of this motor 120 will be further described below. However, in this embodiment, the motor 120 is a DC motor.

[0100] FIG. 18 shows a block diagram of the ECU (electronic control unit) 170. In the motorcycle 1, which is a saddle-ride type vehicle, the ECU 170, which is a control device that controls the operation of the internal combustion engine E and the continuously variable transmission 10, has a configuration as a so-called computer. That is, the ECU 170 has a processor (e.g., a CPU) and a memory (e.g., a ROM and a RAM). The control unit 172 of the ECU 170 has a CPU here, and executes information processing by a program. The CPU is also called a processor. However, the CPU is not limited to a single processor, and may have a multiprocessor configuration. Also, a single CPU connected by a single socket may have a multicore configuration. At least a part of the processing of each of the above-mentioned parts may be performed by a processor other than the CPU, for example, a dedicated processor such as a digital signal processor (DSP) or a graphics processing unit (GPU). Also, at least a part of the processing of each of the above-mentioned parts may be an integrated circuit (IC) or other digital circuit. Also, at least a part of each of the above-mentioned parts may include an analog circuit. The CPU in the control unit 172 executes a computer program executable in its main memory unit, and provides various functions. The main memory in the control unit 172 stores computer programs executed by the CPU and / or data, etc. The main memory in the control unit 172 is a dynamic random access memory (DRAM), a static random access memory (SRAM), a read only memory (ROM), etc.

[0101] The control unit 172 is connected to the storage unit 174. The storage unit 174 is a so-called external storage unit, and is used as a storage area that supplements the main storage unit of the control unit 172, and stores computer programs and / or data executed by the CPU of the control unit 172. The storage unit 174 is a hard disk drive, a solid state drive (SSD), or the like.

[0102] The ECU 170 receives output signals, i.e., output values, from various sensors. For example, an engine speed sensor 176 for detecting the rotation speed (i.e., engine speed) Ne of the crankshaft 20 of the internal combustion engine E, a throttle opening sensor 178 for detecting the opening (throttle opening) Th of the throttle valve 42v of the internal combustion engine E corresponding to the engine load, and a vehicle speed sensor 180 for detecting the vehicle speed are connected to the ECU 170. Here, the vehicle speed sensor 180 is a sensor for detecting the wheel speed of the rear wheels Wr, which are driving wheels. The engine speed sensor 176 is an example of a detection device for detecting the rotation speed of the output shaft of the power source, the throttle opening sensor 178 is an example of a detection device for detecting the load of the power source, and the vehicle speed sensor 180 is an example of a detection device for detecting the vehicle speed.

[0103] The ECU 170 includes an intake control unit 173a, a fuel injection control unit 173b, and an ignition control unit 173c, each of which is a functional module. These control units 173a, 173b, and 173c are realized by executing computer programs stored in a storage unit 174 or the like. For example, the ECU 170 analyzes the operating state of the internal combustion engine E based on inputs from various sensors such as an engine speed sensor 176, a throttle opening sensor 178, and a vehicle speed sensor 180, and controls the operation of the throttle valve 42v by the intake control unit 173a. The ECU 170 also controls the operation of the fuel injection valve 45 by the fuel injection control unit 173b based on the analyzed operating state of the internal combustion engine E. The ECU 170 also controls the operation of an ignition plug 175 facing a combustion chamber by the ignition control unit 173c based on the analyzed operating state of the internal combustion engine E. Furthermore, the ECU 170 controls the operation of the continuously variable transmission 10, that is, the operation of the motor 120. In Fig. 18, the configuration of the ECU 170 related to the automatic shift control of the continuously variable transmission 10 is mainly shown.

[0104] As shown in FIG. 18, the ECU 170 includes a motor control unit 182 which is a functional module. The motor control unit 182 is realized by executing a computer program stored in the storage unit 174 or the like. The motor control unit 182 outputs a control signal, a pulse signal in this case, to a driver 184, and the driver 184 provides the motor 120 with a current of an amount corresponding to the pulse signal. A current sensor 186 for detecting a current (motor current) provided to the motor is further provided, and the current sensor 186 is also connected to the ECU 170, and a signal from the current sensor 186 is also input to the ECU 170. Here, the current sensor 186 includes a shunt resistor. The current sensor 186 is an example of a detection device for detecting the motor current. Note that the current sensor 186 is provided in the ECU 170 here, but may be provided outside the ECU 170.

[0105] The motor control unit 182 is a control unit that controls the motor 120 of the variable speed drive mechanism D. The motor control unit 182 includes an area determination unit 188, a duty control unit 190, a collision determination unit 192, a current control unit 194, a fixed control unit 196, and a feedback (FB) control unit 198, each of which is a functional module, by executing a computer program.

[0106] The region determination unit 188 determines whether the position of the movable driving pulley half 64b of the driving pulley 64 is in a predetermined end region in the axial direction of the movable driving pulley half 64b. Here, in the axial direction, the direction in which the movable driving pulley half 64b moves away from the fixed driving pulley half 64b is the direction in which the speed ratio of the continuously variable transmission 10 increases, and may be referred to as the Low direction or the first axial direction, and the direction in which the movable driving pulley half 64b approaches the fixed driving pulley half 64b is the direction in which the speed ratio of the continuously variable transmission 10 decreases, and may be referred to as the High direction or the second axial direction. The specified end region includes the end region in the direction in which the movable driving pulley half 64b moves away from the fixed driving pulley half 64b, i.e., in the Low direction, that is, the position of the movable driving pulley half 64b when the axial convex portion 142p on the outer periphery of the movable holder 142, which is integrally connected to the movable driving pulley half 64b, abuts against the stopper portion 122s on the inner surface of the right case 122a (Low abutment position) (see Figure 4), and includes a region a specified distance from the Low abutment position in the High direction (Low end region). Here, the predetermined end region includes the end region in the direction in which the movable driving pulley half 64b approaches the fixed driving pulley half 64b, i.e., in the High direction, that is, the position (High abutment position) of the movable driving pulley half 64b when the left axial end 64e of the face surface of the movable driving pulley half 64b abuts against the right axial end 64d of the face surface of the fixed driving pulley half 64a (see FIG. 5), and includes a region (High end region) of a predetermined distance in the Low direction from the High abutment position. Therefore, the region determination unit 188 determines whether the position of the movable driving pulley half 64b of the drive pulley 64 is in the Low end region or the High end region. In the ECU 170, the relationship between the vehicle speed and the speed ratio of the continuously variable transmission 10, i.e., the so-called CVT ratio, is predefined, and the data is stored in the storage unit 174. In determining whether the low end region is present, a determination is made as to whether the gear ratio, i.e., the so-called CVT ratio, calculated by performing a predetermined calculation based on the vehicle speed detected based on the input from the vehicle speed sensor 180, exceeds a determination ratio (Low determination ratio) set as a determination threshold for the low end region. When the CVT ratio exceeds the Low determination ratio, it is determined that the position of the movable drive pulley half 64b is in the Low end region of the predetermined end region.On the other hand, in the judgment regarding the High end region, a judgment is made as to whether or not the gear ratio, i.e., the so-called CVT ratio, calculated by a predetermined calculation based on the vehicle speed detected by the vehicle speed sensor 180, is less than a judgment ratio (High judgment ratio) set as a judgment threshold value for the High end region, and when the CVT ratio is less than the High judgment ratio, it is judged that the position of the movable drive pulley half 64b is in the High end region of the predetermined end region.

[0107] In addition, in order to more reliably determine whether the position of the movable driving pulley half 64b of the driving pulley 64 is in the Low end region or the High end region, the region determination unit 188 determines whether the difference (absolute value) between the target rotation speed of the output shaft of the internal combustion engine E, which is the power source, i.e., the crankshaft 20, and the actual rotation speed of the crankshaft 20 exceeds a predetermined rotation speed. Since the CVT ratio exceeds the Low determination ratio, the predetermined rotation speed, i.e., the Low rotation speed, when it is determined that the position of the movable driving pulley half 64b is in the Low end region may be the same as or different from the predetermined rotation speed, i.e., the High rotation speed, when it is determined that the position of the movable driving pulley half 64b is in the High end region. Here, the determination of whether the difference (absolute value) between the target rotation speed of the output shaft of the power source and its actual rotation speed exceeds the predetermined rotation speed is performed as part of the determination of whether the position of the movable driving pulley half 64b is in the predetermined end region, but it is also possible not to perform this determination.

[0108] As described above, when it is determined that the position of the movable driving pulley half 64b is in the low end region, in the control of the continuously variable transmission 10, the target rotation speed, which is usually determined by performing a predetermined calculation based on the detected vehicle speed and the detected throttle opening, is set to a fixed rotation speed, i.e., a fixed engine rotation speed. On the other hand, when the actual engine rotation speed decreases and becomes equal to or lower than a predetermined vehicle speed, the centrifugal clutch 100 starts to slip, the clutch stall region is entered, and the actual engine rotation speed (actual engine rotation speed) decreases and becomes lower than the fixed engine rotation speed. This is because the fixed engine rotation speed is set as an engine rotation speed that is sufficiently higher than the actual engine rotation speed when the vehicle speed is equal to or lower than the predetermined vehicle speed. Therefore, by comparing the fixed engine rotation speed with the detected actual engine rotation speed, which is the actual rotation speed of the crankshaft 20, when the difference (absolute value) is larger than the low rotation speed, it is determined that the position of the movable driving pulley half 64b of the drive pulley 64 is in the low end region.

[0109] On the other hand, when the position of the movable driving pulley half 64b is determined to be in the High end region as described above, in the control of the continuously variable transmission 10, the operation of the motor 120 is controlled so that the actual engine rotation speed follows the target rotation speed (here, the target engine rotation speed) determined by performing a predetermined calculation based on the detected vehicle speed and the detected throttle opening. In this state, when the left axial end 64e of the face surface of the movable driving pulley half 64b hits the right axial end 64d of the face surface of the fixed driving pulley half 64a, the actual engine rotation speed increases above the target engine rotation speed, and the difference between them becomes large. Therefore, when the target engine rotation speed is compared with the detected actual engine rotation speed, which is the actual rotation speed of the crankshaft 20, and the difference (absolute value) is larger than the High rotation speed, it is determined that the position of the movable driving pulley half 64b of the drive pulley 64 is in the High end region.

[0110] When the position of the movable driving pulley half 64b of the driving pulley 64 is in a predetermined end region in the axial direction of the movable driving pulley half 64b, the duty control unit 190 limits the duty ratio of the control signal, i.e., the pulse signal, from the motor control unit 182 to the driver 184 to a predetermined limit value or less. In particular, when the speed ratio based on the input from the vehicle speed sensor 180, i.e., the so-called CVT ratio, is determined to be in the Low end region because the speed ratio exceeds the Low judgment ratio, or when the CVT ratio is less than the High judgment ratio and the position of the movable driving pulley half 64b is determined to be in the High end region, the duty control unit 190 limits the duty ratio of the control signal, i.e., the pulse signal, from the motor control unit 182 to the driver 184 to a predetermined limit value or less. As a result, the duty ratio of the pulse signal is limited to a predetermined limit value or less, so that the axial movement of the movable driving pulley half 64b can be slowed down. This makes it possible to suppress the impact when the axial convex portion 142p on the outer circumferential side of the movable holder 142 integrally connected to the movable driving pulley half 64b hits the stopper portion 122s on the inner surface of the right case 122a, or the impact when the left axial end portion 64e of the face surface of the movable driving pulley half 64b hits the right axial end portion 64d of the face surface of the fixed driving pulley half 64a. Note that the predetermined limit value when it is determined that the position of the movable driving pulley half 64b is in the Low end region may be the same as or different from the predetermined limit value when it is determined that the position of the movable driving pulley half 64b is in the High end region.

[0111] When it is determined that the position of the movable driving pulley half 64b is in the Low end region, the abutment determination unit 192 determines whether or not the axial convex portion 142p on the outer periphery of the movable holder 142 integrally connected to the movable driving pulley half 64b abuts against the stopper portion 122s on the inner surface of the right case 122a, that is, whether or not the movable driving pulley half 64b is in an abutment state. When it is determined that the position of the movable driving pulley half 64b is in the High end region, the abutment determination unit 192 determines whether or not the left axial end 64e of the face surface of the movable driving pulley half 64b abuts against the right axial end 64d of the face surface of the fixed driving pulley half 64a, as shown in FIG. In this abutment determination, it is determined whether or not the magnitude (absolute value) of the motor current (current value) detected based on the input from the current sensor 186 exceeds a predetermined value (hereinafter, a second predetermined value). When the magnitude (absolute value) of the motor current exceeds the second predetermined value, the abutment determination unit 192 determines that such abutment has occurred. When abutment has occurred, the movable drive pulley half 64b cannot move any further in that direction, so the driver 184 tries to apply a larger current than before. As a result, the detected current may become excessive, so this change in current is used to determine the abutment. In this abutment determination, it is preferable to determine that abutment has occurred when the time during which the magnitude of the motor current exceeds the second predetermined value exceeds a predetermined time. Note that the second predetermined value when it is determined that the position of the movable drive pulley half 64b is in the Low end region may be the same as or different from the second predetermined value when it is determined that the position of the movable drive pulley half 64b is in the High end region.

[0112] When the abutment determination unit 192 determines that abutment has occurred, the current control unit 194 limits the magnitude of the motor current to a predetermined value (hereinafter, the first predetermined value) or less. This makes it possible to prevent the continuous current of the motor current to the motor 120 from becoming too high. Therefore, for example, when the movable driving pulley half 64b reaches a predetermined end in the axial direction of the movable driving pulley half 64b, it is possible to protect the abutted member. Note that the first predetermined value when it is determined that the position of the movable driving pulley half 64b is in the Low end region may be the same as or different from the first predetermined value when it is determined that the position of the movable driving pulley half 64b is in the High end region.

[0113] When the magnitude of the motor current is limited by the current limiting unit 194 to a first predetermined value or less, the fixed control unit 194 controls the motor 120 so that the motor current follows the current of the first predetermined value. Therefore, the gear ratio of the continuously variable transmission 10 is substantially fixed and maintained at a predetermined gear ratio. Specifically, when the magnitude of the motor current is limited when it is determined that the position of the movable driving pulley half 64b is in the Low end region, the fixed control unit 194 controls the operation of the motor 120 so that the gear ratio of the continuously variable transmission 10 is maintained at the gear ratio when the movable driving pulley half 64b is in the Low abutting position as shown in FIG. 4, that is, the fixed gear ratio. On the other hand, when the magnitude of the motor current is limited when it is determined that the position of the movable driving pulley half 64b is in the High end region, the fixed control unit 194 controls the operation of the motor 120 so that the speed ratio of the continuously variable transmission 10 is maintained at the speed ratio when the movable driving pulley half 64b is in the High abutting position, i.e., the fixed speed ratio, as shown in Fig. 5. In particular, the control of the operation of the motor 120 by the fixed control unit 194 is executed when the operating state of the continuously variable transmission 10 is in a region where the centrifugal clutch 100 is not completely connected, i.e., in a clutch stall region, in other words, when the centrifugal clutch 100 is in a state other than the fully connected state, i.e., in a non-completely connected state, for example, when the vehicle speed is equal to or lower than a predetermined vehicle speed. In other words, when the magnitude of the motor current is limited when it is determined that the position of the movable driving pulley half 64b is in the Low end region as described above, the control of the operation of the motor 120 by the fixed control unit 194 is executed. At this time, the target engine rotation speed is set to an engine rotation speed that is sufficiently higher than the actual engine rotation speed Ne, as shown to the left of the line BL in FIG.

[0114] When the centrifugal clutch 100 is in an engaged region, that is, when the centrifugal clutch 100 is in a fully engaged state, the feedback (FB) control section 196 feedback-controls the operation of the motor 120 so that the actual engine speed Ne follows a target speed (here, the target engine speed) determined by performing a predetermined calculation based on the detected vehicle speed and the detected throttle opening. That is, in the control by this feedback control section 196, the gear ratio of the continuously variable transmission 10 is varied, and the rotation direction of the motor 120 and the duty ratio of the control signal are calculated according to a predetermined program so as to eliminate the deviation between the target engine speed and the actual engine speed Ne, and the operation of the motor 120 is controlled based on them. In the control by this feedback control section 196, the following steps are repeated: calculating the deviation between the target engine speed and the actual engine speed Ne, calculating the rotation direction of the motor 120 based on this deviation, and calculating the duty ratio of the control signal of the motor 120 based on this deviation. The throttle opening is an example of an index of the load of the internal combustion engine E, which is the power source.

[0115] The program and data for controlling the motor 120 by the motor control unit 182 are stored in, for example, the storage unit 174. FIG. 19 shows mapped data for controlling the motor 120. In FIG. 19, the horizontal axis indicates the vehicle speed, the vertical axis indicates the engine speed Ne, and the change in the target engine speed (target Ne) according to the throttle opening Th is shown. In FIG. 19, a line of target Ne (Th0%), a line of target Ne (Th10%), a line of target Ne (Th50%), and a line of target Ne (Th100%) are drawn, and for example, the line of target Ne (Th10%) means the target engine speed when the throttle opening is 10%. In addition, the line BL indicates the boundary where the centrifugal clutch 120 is connected, and corresponds to the Low judgment ratio of the region judgment unit 188. In other words, the lower vehicle speed side of the line BL (the left side of the line BL in FIG. 19) corresponds to the stall region where the centrifugal clutch 120 is not completely connected.

[0116] In FIG. 19, as an example, the change in the actual engine speed Ne when the throttle opening is 100% is shown by a line Lne. As shown in FIG. 19, on the lower vehicle speed side of the line BL (on the left side of the line BL in FIG. 19), the target engine speed is set sufficiently higher than the actual engine speed Ne. For example, the actual engine speed Ne1 on the line Lne corresponding to the throttle opening of 100% and the vehicle speed S1 is obviously lower than the target Ne1 which is the target engine speed at the throttle opening of 100% and the vehicle speed S1 (Ne1<target Ne1). In this way, on the lower vehicle speed side of the line BL, the target engine speed is set here so as to be sufficiently higher than the actual speed. Using this difference (for example, Ne1<target Ne1), the above-mentioned region determination unit 188 performs the determination of the Low end region. On the lower vehicle speed side of the line BL (on the left side of the line BL in FIG. 19), the fixed control unit 194 performs the above-mentioned control.

[0117] On the other hand, at higher vehicle speeds than line BL (to the right of line BL in FIG. 19), the feedback control unit 196 executes the above control so that the actual engine speed Ne follows the target engine speed. Therefore, for example, the actual engine speed Ne2 on the line Lne corresponding to a throttle opening of 100% and a vehicle speed S2 is substantially on the line of the target Ne (Th100%).

[0118] The fixation control of the gear ratio by the fixation control unit 194 in the region on the lower vehicle speed side of the line BL (to the left of the line BL in FIG. 19) is the above-mentioned control when the movable driving pulley half 64b is in the Low end region, and the fixation control of the gear ratio by the fixation control unit 194 when the movable driving pulley half 64b is in the High end region can be performed in the region on the higher vehicle speed side of the line BL (to the right of the line BL in FIG. 19). For example, the fixation control by the fixation control unit 194 when the movable driving pulley half 64b is in the High end region may be performed to detect the wear state of the belt 90 when the operation time of the continuously variable transmission 10 exceeds a predetermined time or when the traveling distance of the motorcycle exceeds a predetermined traveling distance. This is to more suitably perform the automatic shift control of the continuously variable transmission 10 according to the wear state of the belt 90.

[0119] Next, the control of the continuously variable transmission 10 by the motor control unit 182 having the above-mentioned configuration, that is, the control method, will be described with reference to the flowchart of FIG.

[0120] In step S2001, the motor control unit 182 of the ECU 170 judges whether the position of the movable driving pulley half 64b of the driving pulley 64 is in a predetermined end region in the axial direction of the movable driving pulley half 64b. This judgment is executed by the region judgment unit 188. In this judgment, as described above, it is judged whether the position of the movable driving pulley half 64b of the driving pulley 64 is in the low end region or the high end region. In the judgment regarding the low end region, it is judged whether the gear ratio calculated by performing a predetermined calculation based on the vehicle speed detected based on the input from the vehicle speed sensor 180, that is, the so-called CVT ratio, exceeds the above-mentioned low judgment ratio, and when the CVT ratio exceeds the low judgment ratio, it is judged that the position of the movable driving pulley half 64b is in the low end region of the predetermined end region. On the other hand, in the judgment regarding the High end region, a judgment is made as to whether or not the gear ratio calculated by a predetermined calculation based on the vehicle speed detected based on the input from the vehicle speed sensor 180, that is, the so-called CVT ratio, is less than the High judgment ratio, and when the CVT ratio is less than the High judgment ratio, it is judged that the position of the movable driving pulley half 64b is in the High end region of the predetermined end region. In this way, by comparing the CVT ratio with the predetermined judgment ratio, it is judged whether or not it is in the predetermined end region. Note that this judgment determines whether the position of the movable driving pulley half 64b is in the Low end region or the High end region, and the threshold value for judgment from step S2003 onwards is set accordingly as described above.

[0121] When it is determined that the position of the movable driving pulley half 64b is in either the low end region or the high end region (positive determination in S2001 in FIG. 20), the duty ratio of the control signal from the motor control unit 182 to the driver 184 is limited to a predetermined limit value α or less (S2003 in FIG. 20). As a result, when the duty ratio reaches the predetermined limit value α thereafter, the duty ratio is limited to the predetermined limit value α or less, so that the axial movement of the movable driving pulley half 64b can be slowed down, and therefore, the impact of the abutment against the stopper portion 122s when the pulley half 64b is in the low end region can be suppressed. Here, when the duty ratio reaches the predetermined limit value α, the duty ratio is limited to and maintained at the predetermined limit value α. On the other hand, when it is not determined that the position of the movable driving pulley half 64b is in either the Low end region or the High end region (negative determination in S2001 of FIG. 20), the restriction of the duty ratio of the control signal from the motor control unit 182 to the driver 184 to be equal to or less than the predetermined limit value α is lifted (S2004 of FIG. 20).

[0122] Then, in step S2005 following step S003, it is determined whether the difference between the target rotation speed of the output shaft of the internal combustion engine E, i.e., the crankshaft 20, i.e., the target engine rotation speed, and the actual rotation speed of the crankshaft 20, i.e., the actual engine rotation speed Ne, i.e., the magnitude of the Ne deviation (|Ne deviation|) is greater than a predetermined rotation speed β. The target engine rotation speed is calculated by performing an operation based on the throttle opening Th detected based on the input from the throttle opening sensor 178 and the vehicle speed detected based on the input from the vehicle speed sensor 180, based on the mapped data as shown in FIG. 19. The actual engine rotation speed Ne is detected based on the input from the engine rotation speed sensor 176. Then, the difference between the target engine rotation speed and the actual engine rotation speed Ne, i.e., the Ne deviation, is calculated, and the magnitude of the Ne deviation is compared with the predetermined rotation speed β, which is a predetermined value. When the magnitude of the Ne deviation is greater than the predetermined rotation speed β, an affirmative determination is made in step S2003. When a negative determination is made in step S2005, the process proceeds to step S2015 described below, rather than proceeding to step S2004 for removing the restriction on the duty ratio.

[0123] When it is determined that the magnitude of the Ne deviation (|Ne deviation|) exceeds the predetermined rotation speed β (positive determination in S2005 in FIG. 20), it is determined whether or not the movable driving pulley half 64b is in an abutting state (S2007, S2008 in FIG. 20). That is, it is determined here whether or not the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b. Step S2007 is a determination as to whether or not the magnitude of the motor current exceeds a second predetermined value γ. Then, when it is determined positive in step S2007 that the magnitude of the motor current exceeds the second predetermined value γ, it is determined in the next step S2008 whether or not the time by which the motor current has exceeded the predetermined time. That is, when a positive determination is made in step S2007, time measurement is started by the timer means of the ECU 170, and it is determined in step S2008 whether or not the measured time has exceeded the predetermined time. When a negative determination is made in step S2008 that the measured time has not exceeded the predetermined time, the process returns to step S2001. When the measured time exceeds the predetermined time in step S2008, an affirmative determination is made, which means that the movable drive pulley half 64b is determined to be in an abutting state. This determination (S2007 and S2008 in FIG. 20) corresponds to a determination as to whether the movable pulley half 64b has reached a predetermined end, and is performed by the abutment determination unit 192.

[0124] When it is determined that the movable driving pulley half 64b is in the butted state (positive determination in S2007 and S2008 in FIG. 20), the process proceeds to step S2009, where a butted determination flag indicating that a butted determination has been made is set to an ON state. As a result, the process proceeds to step S2010, where the magnitude of the motor current is limited to a first predetermined value or less. Here, the magnitude of the motor current is limited to the first predetermined value. This current limitation is performed by the current limiting unit 194. Then, the process proceeds to step S2011, where the fixed control is set so that the fixed control unit 194 performs the fixed control. As a result, the motor 120 is controlled so that the motor current follows the first predetermined value. Thus, it is possible to prevent an excessive current from being continuously supplied to the motor 120, and it is possible to maintain the movable driving pulley half 64b in the butted state (see FIG. 4 or FIG. 5). Note that the determination flag is provided here and can be used in other determination processes of the ECU 170, but it is not necessary to provide it.

[0125] On the other hand, if a negative judgment is made in any of steps S2001, S2005, and S2007, the process proceeds to step S2013, where the collision judgment is released and the collision judgment flag is set to an OFF state. If the collision judgment flag was in an OFF state up until that point, the process is simply passed and the OFF state is maintained. Then, in step S2015, the current limit is released. This release of the current limit is performed when the magnitude of the motor current has been limited to a first predetermined value or less up until that point in step S2010, and otherwise the process is simply passed. Then, in step S2017, the feedback control (FB control) is set by the feedback control unit 196. As described above, in the feedback control, the centrifugal clutch 100 is connected, and the operation of the motor 120 is controlled so that the actual engine rotation speed Ne follows the target rotation speed (here, the target engine rotation speed) that is determined by performing a predetermined calculation based on the detected vehicle speed and the detected throttle opening.

[0126] Here, the determination of whether the movable driving pulley half 64b is in the low abutting position as shown in Fig. 4 will be further described based on the timing chart of Fig. 21. Fig. 21 shows the time on the horizontal axis, the change in the actual engine rotation speed Ne (indicated as "actual Ne" in the figure) with respect to the target engine rotation speed (target Ne) shown by the dashed line, the change in the position of the movable driving pulley half 64b (pulley position in Fig. 21), the change in the duty ratio of the control signal from the motor control unit 182, and the change in the motor current of the motor 120. Note that "H" and "L" in Fig. 21 of the pulley position indicate the high direction and the low direction, respectively. Also, the "+" direction of the motor current corresponds to the rotation direction of the motor 120 for moving the movable driving pulley half 64b in the low direction.

[0127] When the actual engine speed reaches the stall region where the centrifugal clutch 100 slips while the above-mentioned feedback control is being performed, that is, when it reaches the line BL from the region on the right side of the line BL in the graph of FIG. 19 (timing "t11" in FIG. 21), the actual engine speed Ne starts to decrease so as to move away from the target engine speed. At this time, when the gear ratio calculated based on the vehicle speed detected based on the input from the vehicle speed sensor 180, that is, the CVT ratio, exceeds the Low judgment ratio, it is judged that the position of the movable driving pulley half 64b is in the Low end region of the predetermined end region (timing "t21" in FIG. 22, positive judgment in S2001 in FIG. 20). As a result, the duty ratio of the control signal from the motor control unit 182 to the driver 184 is limited to a predetermined limit value α or less (S2003 in FIG. 20). Then, when the magnitude of the Ne deviation (|Ne deviation|) becomes larger than the predetermined rotation speed β (timing t12 in FIG. 21), it is determined with greater certainty that the position of the movable driving pulley half 64b is in the Low end region (positive determination in S2005 in FIG. 20).

[0128] At this time, since the target engine rotation speed is set to a fixed engine rotation speed, the motor control unit 182 increases the duty ratio of the control signal so that the actual engine rotation speed follows the target engine rotation speed. As a result, when the duty ratio reaches the predetermined limit value α (timing "t13" in FIG. 21), since the duty ratio is already limited to or below the predetermined limit value α (S2003 in FIG. 20), the duty ratio is maintained to or below the predetermined limit value α, and is substantially maintained at the predetermined limit value α here. Then, the motor current gradually decreases as the load is reduced, but when the movable driving pulley half 64b reaches the low abutting position and enters an abutting state (timing "t14" in FIG. 21), the motor current begins to increase. As a result, when the magnitude of the detected motor current reaches the second predetermined value γ (timing "t15" in FIG. 21, affirmative judgment in step S2007) and the time during which the motor current reaches the second predetermined value γ (time between t15 and t16) has elapsed a predetermined time (timing "t16" in FIG. 21, affirmative judgment in S2008), it is judged that the movable driving pulley half 64b is in an abutting state. Therefore, the abutting judgment flag indicating that abutting judgment has been made is set to the ON state (S2009 in FIG. 20).

[0129] As a result, since the movable driving pulley half 64b is in the abutting state, the magnitude of the motor current is limited to a first predetermined value (current limit value) that is lower than the above-mentioned second predetermined value γ (S2010 in FIG. 20). This current limiting is performed by the current limiting unit 194. As a result, the setting is made so that fixed control is performed (S2011). As a result, the motor 120 is controlled so that the motor current follows the first predetermined value.

[0130] Next, the determination that the movable driving pulley half 64b is in the High abutting position as shown in Fig. 5 will be further described based on the timing chart of Fig. 22. In Fig. 22, similar to Fig. 21, the horizontal axis indicates time, and the change in the actual engine rotation speed Ne (indicated as "actual Ne" in the figure) with respect to the target engine rotation speed (target Ne) indicated by the dashed line is shown, as well as the change in the position (pulley position) of the movable driving pulley half 64b, the change in the duty ratio of the control signal from the motor control unit 182, and the change in the motor current of the motor 120. Note that the "-" direction of the motor current corresponds to the rotation direction of the motor 120 for moving the movable driving pulley half 64b in the High direction.

[0131] When the above-mentioned feedback control is performed, if the speed ratio calculated based on the vehicle speed detected based on the input from the vehicle speed sensor 180, that is, the CVT ratio, becomes less than the High judgment ratio, it is judged that the position of the movable driving pulley half 64b is in the High end region of the predetermined end region (timing "t21" in FIG. 22, positive judgment in S2001 in FIG. 20). As a result, the duty ratio of the control signal from the motor control unit 182 to the driver 184 is limited to a predetermined limit value α or less (S2003 in FIG. 20). Then, when the movable driving pulley half 64b reaches the High abutting position and enters an abutting state (timing "t22" in FIG. 22), the actual engine rotation speed Ne starts to increase so as to move away from the target engine rotation speed. Then, when the magnitude of the Ne deviation (|Ne deviation|) becomes larger than the predetermined rotation speed β (timing "t23" in FIG. 22), it is more reliably judged that the position of the movable driving pulley half 64b is in the High end region (positive judgment in S2005 in FIG. 20).

[0132] At this time, the motor control unit 182 increases the duty ratio of the control signal so that the actual engine rotation speed follows the target engine rotation speed. As a result, when the duty ratio reaches the predetermined limit value α (timing "t24" in FIG. 21), since the duty ratio has already been limited to or below the predetermined limit value α (S2003 in FIG. 20), the duty ratio is maintained below the predetermined limit value α, and is substantially maintained at the predetermined limit value α here. Then, the magnitude of the motor current also starts to increase in the same manner as the duty ratio. As a result, when the magnitude of the detected motor current reaches the second predetermined value γ (timing "t25" in FIG. 21, positive judgment in step S2007) and the time during which the motor current has reached the second predetermined value γ has elapsed (time between t25 and t26) (timing "t26" in FIG. 21, positive judgment in S2008), it is judged that the movable driving pulley half 64b is in abutment state. Therefore, abutment judgment flag indicating that abutment judgment has been made is set to an ON state (S2009 in FIG. 20).

[0133] As a result, since the movable driving pulley half 64b is in the abutting state, the magnitude of the motor current is limited to a first predetermined value (current limit value) that is lower than the above-mentioned second predetermined value γ (S2010 in FIG. 20). This current limiting is performed by the current limiting unit 194. As a result, the setting is made so that fixed control is performed (S2011 in FIG. 20). As a result, the motor 120 is controlled so that the motor current follows the first predetermined value.

[0134] When the position of the movable driving pulley half 64b is in the High end region, the deviation of the actual engine rotation speed Ne from the target engine rotation speed occurs after the movable driving pulley half 64b is in the abutting state. Therefore, when the position of the movable driving pulley half 64b is in the High end region, the increase in the magnitude of the current of the motor 120 occurs along with the increase in its |Ne deviation|, so the abutment determination may be performed earlier than when the position of the movable driving pulley half 64b is in the Low end region. For example, in the flowchart of FIG. 20, step S2005 may be omitted or moved between steps S2007 and S2008. This also applies to the limitation of the magnitude of the current (S2010 in FIG. 20).

[0135] Next, based on the timing chart of Fig. 23, a description will be given of the transition from the operating state of the centrifugal clutch 100 in the stall region, i.e., the fixed control region, to the feedback control region on the right side of the line BL in Fig. 19. In Fig. 23, similar to Fig. 21, the horizontal axis indicates time, and the change in the actual engine speed Ne (indicated as "actual Ne" in the figure) is shown with respect to the target engine speed (target Ne) indicated by the dashed line, as well as the change in the position (pulley position) of the movable driving pulley half 64b, the change in the duty ratio of the control signal from the motor control unit 182, and the change in the motor current of the motor 120. Fig. 23 also shows the change in the throttle opening Th and the ON (S2010 in Fig. 20) and OFF (S2015 in Fig. 20) of the current limiting.

[0136] As shown in FIG. 4, when the movable driving pulley half 64b is in the low abutting position, the actual engine speed Ne is away from the fixed engine speed which is the target engine speed, and since the motor current is limited as described above, the motor current is approximately constant at the first predetermined value (current limit value), and the duty ratio of the control signal is also approximately constant. In this state, when the throttle opening increases, the fixed engine speed also changes according to the change in the throttle opening, as shown in FIG. 19. Then, when the engine speed gets on the line BL as described in FIG. 19, the engine speed Ne approaches the target engine speed, and the centrifugal clutch is engaged ("t31 timing" in FIG. 23). Then, when the magnitude of the Ne deviation (|Ne deviation|) becomes equal to or less than the predetermined engine speed β ("t32" timing in FIG. 23, negative determination in S2005 in FIG. 20), the current limit is released (S2015 in FIG. 20). As a result, the above-mentioned feedback control is performed (S2017 in FIG. 20).

[0137] In this way, in the control of the above-mentioned continuously variable transmission 10, it is possible to appropriately determine whether the movable driving pulley half 64b is in the low abutment position (see Figure 4) and whether the movable driving pulley half 64b is in the high abutment position (see Figure 5) and has reached that position, without providing a sensor for detecting the position of the movable driving pulley half 64b on the driving pulley 64 or the movable driving pulley half 64b.

[0138] Further, a centrifugal clutch 100 is provided between the driven pulley 94 and the driven shaft 92 of the continuously variable transmission. When the centrifugal clutch 100 is in a completely connected state, feedback control is performed to control the operation of the motor 120 so that the detected actual engine speed follows a target engine speed calculated by performing a predetermined calculation based on the detected vehicle speed and the detected throttle opening, that is, ratio feedback control. On the other hand, when the centrifugal clutch 100 is in an incompletely connected state, which includes the slipping of the centrifugal clutch 100, control is performed to limit the motor current as described above, that is, fixation control is performed.

[0139] The operation and effects of the control of the motor 120 by the ECU 170, which is the control device for the continuously variable transmission 10 described above, will be described below.

[0140] The continuously variable transmission 10 includes a drive pulley 64 to which a driving force is transmitted from the crankshaft 20 of the internal combustion engine E, a driven pulley 94 equipped with a centrifugal clutch 100, and a belt 90 stretched between the drive pulley 64 and the driven pulley 94. The centrifugal clutch 100 rotates integrally with the driven pulley 94 and is connected when a predetermined rotation speed is exceeded, thereby transmitting the driving force of the internal combustion engine E to the drive wheel Wr. The ECU 170 of the continuously variable transmission 10 includes a motor control unit 182 that controls a motor 120 that generates a driving force in the axial direction of the movable drive pulley half 64b in the drive pulley 64 so as to move the movable drive pulley half 64b relative to the fixed drive pulley half 64a. As described above, when the centrifugal clutch 100 is in a non-fully connected state, the motor control unit 182 controls the motor 120 to maintain the gear ratio of the continuously variable transmission 10 at a fixed gear ratio (S2011 in FIG. 20), and when the centrifugal clutch 100 is in a fully connected state, feedback controls the operation of the motor 120 based on the detected vehicle speed and the detected throttle opening (S2017 in FIG. 20).

[0141] According to this configuration, when the centrifugal clutch 100 is in an incompletely connected state, that is, when the centrifugal clutch 100 is slipping or disengaged, the motor 120 is controlled so as to maintain the gear ratio of the continuously variable transmission 10 at a fixed gear ratio. Therefore, when the centrifugal clutch 100 is in an incompletely connected state, the motor 120 can be controlled without the need to accurately grasp the driving state of the driven pulley 94, for example, its rotational speed, and the gear ratio of the continuously variable transmission 10 can be controlled to a fixed gear ratio. Therefore, for example, a sensor for detecting the rotational speed of the driven pulley 94 can be omitted from inside the case of the continuously variable transmission 10. In this way, according to the above configuration, it is possible to control the gear ratio to a target gear ratio while reducing the number of parts in the transmission case. When the centrifugal clutch 100 is in a fully connected state, the operation of the motor 120 is feedback controlled so that the actual engine speed follows the target engine speed determined based on the detected vehicle speed and the detected throttle opening, and in this case, the feedback control is possible even if there is no sensor inside the transmission case for detecting the rotation speed of the driven pulley 94. This is because when the centrifugal clutch 100 is in a fully connected state, the vehicle speed and the rotation speed of the driven pulley 94 correspond to each other.

[0142] When controlling the motor 120 so as to maintain the speed ratio of the continuously variable transmission 10 at the fixed speed ratio, the motor control unit 182 executes the following: limiting the magnitude of the current of the motor 120 to a first predetermined value α or less (S2010 in FIG. 20); and limiting the duty ratio of the control signal to the motor 120 to a predetermined limit value β or less (S2003 in FIG. 20). According to this configuration, even if the movable driving pulley half 64b hits, for example, the stopper portion 122s, the duty ratio is limited to a predetermined limit value β or less, so that the speed of movement of the movable driving pulley half 64b can be slowed down, and the collision load at the time of the hitting can be suppressed, thereby protecting each component. Furthermore, by limiting the magnitude of the current of the motor 120 to a predetermined value α or less, it is possible to prevent the continuous energization current to the motor 120 from becoming excessive, thereby making it possible to protect the motor 120.

[0143] Furthermore, when the motor 120 is controlled to maintain the speed ratio of the continuously variable transmission 10 at a fixed speed ratio, the movable driving pulley half 64b reaches a predetermined end in the axial direction of the movable driving pulley half 64b. According to this configuration, when the motor 120 is controlled to maintain the speed ratio of the continuously variable transmission 10 at a fixed speed ratio, the movable driving pulley half 64b reaches a predetermined end in the axial direction of the movable driving pulley half 64b, so that the speed ratio of the continuously variable transmission 10 can be controlled to the fixed speed ratio with simpler control.

[0144] Furthermore, when the centrifugal clutch 100 is in an incompletely connected state, the motor control unit 182 executes the following: determining whether or not the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b based on the current of the motor 120 (S2007, S2008 in FIG. 20); and, when it is determined that the movable driving pulley half 64b has reached the predetermined end in the axial direction of the movable driving pulley half 64b, controlling the operation of the motor 120 so as to maintain the speed ratio of the continuously variable transmission 10 at a fixed speed ratio (S2011 in FIG. 20). According to this configuration, it is determined whether or not the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b based on the current of the motor 120. Therefore, it is possible to detect the arrival of the movable driving pulley half 64b at the predetermined end without providing a sensor that directly detects the position of the movable driving pulley half 64b, for example. Then, when it is determined that the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b, the motor 120 is controlled to maintain the speed ratio of the continuously variable transmission 10 at a fixed speed ratio. Thus, in controlling the continuously variable transmission 10, it becomes possible to move the movable driving pulley half 64b in a wide range including the point where the movable driving pulley half 64b reaches the predetermined end, and therefore it becomes possible to further expand the movable range of the movable driving pulley half 64b of the drive pulley 64.

[0145] When it is determined that the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b, the abutment portion on the movable driving pulley half 64b side, i.e., the axial convex portion 142p, abuts against the stopper portion 122s that restricts the axial movement of the movable driving pulley half 64b in the direction away from the fixed driving pulley half 64b. This makes it possible to limit the abutment of the movable driving pulley half 64b to the axial convex portion 142 and the stopper portion 122s, and it is possible to more reliably protect other members.

[0146] In addition, when the position of the movable driving pulley half 64b is in a predetermined end region in the axial direction of the movable driving pulley half 64b, i.e., the low end region or the high end region, the motor control unit 182 executes the following: limiting the duty ratio of the control signal of the motor 120 to a predetermined limit value or less (S2003 in FIG. 20); and judging whether the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b, i.e., the low abutment position or the high abutment position, based on the current of the motor 120 detected when the duty ratio is limited to the predetermined limit value β or less (S2007, S2008 in FIG. 20). Therefore, when the position of the movable driving pulley half 64b is in the predetermined end region, the duty ratio of the control signal of the motor 120 is limited to a predetermined limit value or less, thereby making it possible to protect the movable driving pulley half 64b from abutment. Then, based on the detected current of the motor 120, it is determined whether the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b. Therefore, it is possible to detect the arrival of the movable driving pulley half 64b at the predetermined end without providing a sensor that directly detects the position of the movable driving pulley half 64b. Therefore, in the automatic speed change control of the continuously variable transmission 10, it is possible to move the movable driving pulley half 64b in a wide range including the point where the movable driving pulley half 64b reaches the predetermined end, and therefore it is possible to further expand the movable range of the movable driving pulley half 64b of the drive pulley 64.

[0147] In addition, when the magnitude of the difference between the target rotation speed of the crankshaft 20, which is the output shaft of the internal combustion engine E as the power source (here, the target engine rotation speed) and the actual rotation speed of the crankshaft (here, the actual engine rotation speed Ne) is greater than a predetermined rotation speed β, the motor control unit 182 executes a determination as to whether or not the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b based on the current of the motor 120 detected at that time. When the position of the movable driving pulley half 64b is in the predetermined end area, the magnitude of the difference between the target rotation speed of the crankshaft 20 of the internal combustion engine E and the actual rotation speed of the crankshaft 20 becomes greater than the predetermined rotation speed, so at this time, based on the current of the motor 120 detected, a determination as to whether or not the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b is performed. This makes it possible to more effectively determine whether the movable drive pulley half 64b has hit the ground while reducing the computation load on the ECU 170.

[0148] Furthermore, when it is determined that the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b, that is, the low abutment position or the high abutment position (S2007, S2008 in FIG. 20), the motor control unit 182 further executes limiting the magnitude of the current (motor current) of the motor 120 to a first predetermined value or less, particularly to the first predetermined value. According to this configuration, when the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b, the magnitude of the current of the motor 120 is limited to the first predetermined value, so that, for example, it is possible to prevent an excessive current from continuing to flow in the motor 120, and therefore it is possible to protect the motor 120 itself.

[0149] Furthermore, when the time during which the magnitude of the detected current of the motor 120 reaches a second predetermined value higher than the first predetermined value exceeds a predetermined time, the motor control unit 182 executes the process of determining that the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b (S2008 in FIG. 20). According to this configuration, it is possible to more accurately determine that the movable driving pulley half 64b has reached the predetermined end.

[0150] Although one embodiment of the present invention and its modified examples have been described above, the present invention is not limited to the above-described embodiment, and various other modifications are possible within the scope of the gist of the present invention. For example, the power unit and internal combustion engine of the present invention may be widely applied to other types of saddle-type vehicles, not limited to motorcycles. For convenience of explanation, the left and right arrangement of the device has been described according to the illustrated embodiment, but is not limited thereto, and the left and right arrangement may be reversed.

[0151] In the above embodiment, the cam assist mechanism is of the ball cam type, but other types that convert the rotational motion of the output shaft of the power source into axial motion of the output shaft may be adopted. The mechanism (axial slide mechanism) that moves the movable drive pulley half 64b in the axial direction relative to the fixed drive pulley half 64a by the operation of the drive mechanism is not limited to the cam assist mechanism C, and may be, for example, a mechanism that simply allows the movable drive pulley half 64b to move in the axial direction relative to the fixed drive pulley half 64a by the axial driving force of the drive mechanism D. The power source may be something other than an internal combustion engine. [Explanation of symbols]

[0152] 1...motorcycle, 10...belt-type continuously variable transmission, 20...crankshaft, 64...drive pulley 64a...fixed drive pulley half, 64b...movable drive pulley half, 90...V-belt, 94...driven pulley 94a... fixed driven pulley half, 94b... movable driven pulley half, 120... motor, 130... first reduction gear 132: second reduction gear, 134: screw member, 142: movable holder 170...Electronic control unit (ECU), C...Cam assist mechanism D... Drive mechanism, E... Internal combustion engine, P... Power unit

Claims

1. A control device (170) for a belt-type continuously variable transmission (10) including: a drive pulley (64) to which a driving force is transmitted from an output shaft (20) of a power source (E) of a vehicle (1); a driven pulley (94) equipped with a centrifugal clutch (100) which rotates integrally with the driven pulley (94) and is connected to the driven pulley (94) when a predetermined rotation speed is exceeded, thereby transmitting the driving force of the power source (E) to a driving wheel (Wr) of the vehicle (1); and a belt (90) stretched between the drive pulley (64) and the driven pulley (94), a control unit (182) for controlling a motor (120) that generates a driving force in an axial direction of the movable pulley half (64b) so as to move the movable pulley half (64b) relative to the fixed pulley half (64a) in the drive pulley (64), The control unit (182) performing duty control of the motor (120) to limit a duty ratio to a predetermined limit value or less when the position of the movable pulley half (64b) is in a low end region, which is an end region in a low direction where the movable pulley half (64b) is away from the fixed pulley half (64a) in the axial direction, or when the movable pulley half (64b) is in a high end region, which is an end region in a high direction where the movable pulley half (64b) approaches the fixed pulley half (64a) in the axial direction; controlling the motor (120) so as to maintain a speed ratio, which is controlled by a position of a movable pulley half (64b) relative to a fixed pulley half (64a) of a drive pulley (64) of the continuously variable transmission (10), at a fixed speed ratio when the centrifugal clutch (100) is in an incompletely connected state; feedback control of the operation of the motor (120) based on the detected vehicle speed and the detected load of the power source when the centrifugal clutch (100) is in a fully engaged state; Run When controlling the motor (120) to maintain the speed ratio of the continuously variable transmission (10) at the fixed speed ratio, the control unit (182) executes the following: limiting the magnitude of the current of the motor (120) to a predetermined value greater than zero or less, and limiting the duty ratio of a control signal to the motor (120) to a predetermined limit value or less. A control device (170) for a belt-type continuously variable transmission (10).

2. When the motor (120) is controlled so as to maintain the speed ratio of the continuously variable transmission (10) at a fixed speed ratio, the movable pulley half (64b) reaches a predetermined end in the axial direction of the movable pulley half (64b).

2. The control device (170) for a belt-type continuously variable transmission (10) according to claim 1.

3. The control unit (182) determining, based on a current of the motor (120), whether or not the movable pulley half (64b) has reached the predetermined end in the axial direction of the movable pulley half (64b) when the centrifugal clutch (100) is in an incompletely connected state; when it is determined that the movable pulley half (64b) has reached the predetermined end in the axial direction of the movable pulley half (64b), controlling the motor (120) so as to maintain the speed ratio of the continuously variable transmission (10) at a fixed speed ratio; Run 3. The control device (170) for a belt-type continuously variable transmission (10) according to claim 2.

4. When it is determined that the movable pulley half (64b) has reached the predetermined end in the axial direction of the movable pulley half (64b), the abutment portion (142p) on the movable pulley half (64b) abuts against a stopper portion (122s) that restricts the movement of the movable pulley half (64b) in the axial direction in a direction away from the fixed pulley half (64b).

4. The control device (170) for a belt-type continuously variable transmission (10) according to claim 2 or 3.

5. A belt-type continuously variable transmission (10) including a drive pulley (64) to which a driving force is transmitted from an output shaft (20) of a power source (E) of a vehicle (1), a driven pulley (94) equipped with a centrifugal clutch (100) which rotates integrally with the driven pulley (94) and is engaged when a predetermined rotation speed is exceeded to transmit the driving force of the power source (E) to a driving wheel (Wr) of the vehicle (1), and a belt (90) stretched between the drive pulley (64) and the driven pulley (94), comprising: a control method for controlling a motor (120) which generates a driving force in an axial direction of a movable pulley half (64b) so as to move the movable pulley half (64b) relative to a fixed pulley half (64a) in the drive pulley (64), the motor (120) is duty-controlled to limit a duty ratio to a predetermined limit value or less when the position of the movable pulley half (64b) is in a low end region, which is an end region in a low direction where the movable pulley half (64b) is away from the fixed pulley half (64a) in the axial direction, or when the movable pulley half (64b) is in a high end region, which is an end region in a high direction where the movable pulley half (64b) approaches the fixed pulley half (64a) in the axial direction; a step of controlling the motor (120) so as to maintain a speed ratio, which is controlled by a position of a movable pulley half (64b) relative to a fixed pulley half (64a) of a drive pulley (64) of the continuously variable transmission (10) at a fixed speed ratio when the centrifugal clutch (100) is in an incompletely connected state, the step of limiting a magnitude of a current of the motor (120) to a predetermined value greater than zero and limiting a duty ratio of a control signal to the motor (120) to a predetermined limit value or less when controlling the motor (120) so as to maintain the speed ratio of the continuously variable transmission (10) at the fixed speed ratio; feedback controlling the operation of the motor (120) based on the detected vehicle speed and the detected load of the power source when the centrifugal clutch (100) is in a fully engaged state; Includes A control method comprising:

6. the step of controlling the motor (120) so as to maintain the gear ratio of the continuously variable transmission (10) at a fixed gear ratio when the centrifugal clutch (100) is in an incompletely connected state, determining whether or not the movable pulley half (64b) has reached a predetermined end in the axial direction of the movable pulley half (64b) based on a current of the motor (120) when the centrifugal clutch (100) is in an incompletely connected state; controlling the motor (120) so as to maintain a speed ratio of the continuously variable transmission (10) at a fixed speed ratio when it is determined that the movable pulley half (64b) has reached the predetermined end in the axial direction of the movable pulley half (64b); Includes 6. The control method according to claim 5.

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