Clutch device for continuously variable transmission

Abstract: Clutches for interrupting power transmission between a V-belt (21) and a drive pulley (11) by pushing up the V-belt are provided on groove side faces fixed and movable sheaves (12,13) in the bottom of a belt groove of the drive pulley in a belt-type continuously variable transmission. Each clutch (31) includes a fixed plate (33) fixed on a fixed sheave, a rotating plate (34) that rotates by being pressed by the belt, and multiple rollers (35) extending obliquely with a predetermined angle with respect to the radial direction of the rotating plate. The rollers are held rotatably by a holding member (36) with an interval therebetween. In the state where the belt is in contact with the clutches, the rollers held by the holding plate are rolling by the relative rotation between the rotating plate and the fixed plate, while sliding along the rotation direction of the rotating plate, which is oblique to the rolling direction. The disconnection of the power transmission can be performed smoothly while the cost of the belt-type continuously variable transmission is reduced.

Description: BACKGROUND OF THE INVENTION The present invention relates to continuously variable transmissions and vehicles provided with the same. Conventionally, as a rolling friction device, a device having the following configuration as disclosed in Japanese Laid-Open Patent Publication No. 8-74843 has been proposed. A pair of ring-shaped rotating members is arranged concentrically, opposing to each other, multiple rollers extending obliquely with a predetermined angle with respect to the radial direction of the rotating members are arranged along the circumferential direction of the rotating members between the two rotating members, and these rollers are held rollably by a holding member with intervals therebetween. This proposed example is characterized in that the rollers can be rolled while being slid between the two rotating members, so that the friction coefficient involved in relative rotation between the two rotating members can be kept constant and therefore the rotation resistance can be stable. JP 54 1146 72 described a continuously variable transmission comprising the features mentioned in the preamble of claims 1 or 2. Today, a centrifugal clutch is generally mounted together with a belt-type continuously variable transmission of a weight roller type for motorbikes such as motor-scooters or minibikes, on which an engine of a small exhaust amount is mounted. The continuously variable transmission of a weight roller type has a weight roller that is moved by the centrifugal force, and the movement of the weight roller drives the movable sheave of the variable speed pulley to shift the transmission. On the other hand, a centrifugal clutch has a weight that is moved by the centrifugal force as in the case of the continuously variable transmission of the weight roller type. The movement of this weight interrupts the power transmission between the engine and the driving wheel (rear wheel). This centrifugal clutch is generally disposed on the driven side of the continuously variable transmission. However, the centrifugal clutch is expensive and it is difficult to reduce the cost. In order to utilize smooth transmission by the continuously variable transmission and to start the vehicle smoothly in accordance with the increase of the rotation speed of the engine at the time of the start, a clutch that can disconnect power transmission smoothly is in demand. SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to disconnect power transmission smoothly by a clutch while reducing the cost by providing a clutch utilizing the configuration of a variable speed pulley. In order to achieve the above object, the proposed rolling friction device is incorporated between the rotating shaft and the variable speed pulley or at least into a groove side face on the side of a fixed sheave in the belt groove surface of a variable speed pulley, and power transmission between the rotating shaft and the variable speed pulley or power transmission between the belt and the variable speed pulley can be disconnected by this rolling friction device. More specifically, the present invention is based on a continuously variable transmission including a variable speed pulley having fixed and movable sheaves that are rotatably provided on a rotating shaft and opposed to each other, in which a belt groove is formed between the sheaves; and a V-belt wounded in the belt groove of the variable speed pulley, wherein transmission is shifted by changing the belt diameter during wind in the belt groove by moving the movable sheave close to and away from the fixed sheave to open and close the variable speed pulley. Clutch means for disconnecting power transmission between the rotating shaft and the variable speed pulley is provided. The clutch means includes a pair of ring-shaped rotating members that are arranged such that they are concentrically opposed to each other and can rotate relative to each other; multiple rollers that are arranged along the circumferential direction of the rotating members between the two rotating members and whose rolling axis center is extending obliquely with a predetermined angle with respect to the radial direction of the rotating members; and a holding member for holding the multiple rollers such that the rollers are spaced away from each other and can roll. When the rotating members are pressed against the opposing rotating members, a connection state is established. One of the rotating members is provided on one side of the variable speed pulley or the rotating shaft, and the other rotating member is provided in the other side of the variable speed pulley or the rotating shaft. According to the above embodiment, when the clutch means is in a non-connection state (OFF state) and the power transmission between the rotating shaft and the variable speed pulley is interrupted, then one of the two rotating members of the clutch is not pressed to the shaft direction so as to be directed to the other rotating member. However, when this clutch means is switched to a connection state (ON state), one of the two rotating members is pressed to the shaft direction so as to be directed to the other rotating member, so that power transmission is performed between the rotating shaft and the variable speed pulley. In this power transmission state, the continuously variable transmission is shifted, and in the transmission-shift state, the movable sheave moves close to and away from the fixed sheave to open and close the variable speed pulley, so that the V-belt moves in the belt groove to the radial direction to change the belt diameter during wind in the belt groove. Thus, the continuously variable transmission is shifted. At this time, the clutch means has a pair of rotating members, one provided in the variable speed pulley and the other in the rotating shaft, and multiple rollers whose rolling axis center is extending obliquely with a predetermined angle with respect to the radial direction of the rotating members are arranged between the rotating members. These rollers are spaced away from each other and rollably held by a holding member. Therefore, when the rotating members roll while being pressed to the opposing rotating members, the rollers slide along the rotation direction of the rotating member by the relative rotation of the two rotating members while rolling in the state where the rollers are held by a holding member. The rolling and the slide of the rollers can provide a stable rotation resistance. Therefore, such clutch means for performing the rolling and the slide of the rollers allow power transmission between the rotating shaft and the variable speed pulley to be disconnected smoothly. The clutch means is provided between the rotating shaft and the variable speed pulley, and is attached to the pulley, so that the configuration of the continuously variable transmission can be simple and compact. In addition, the clutch means has a simpler configuration than that of a centrifugal clutch having a weight and is inexpensive so that the cost of the continuously variable transmission can be reduced. Furthermore, the present invention is based on a continuously variable transmission including a variable speed pulley having fixed and movable sheaves that are provided on a rotating shaft and opposed to each other, in which a belt groove is formed between the sheaves; and a V-belt wounded in the belt groove of the variable speed pulley, wherein the transmission is shifted by changing the belt diameter during wind in the belt groove by moving the movable sheave close to and away from the fixed sheave to open and close the variable speed pulley. Clutch means for disconnecting power transmission between the V-belt and the variable speed pulley is provided at least on a groove side face on the fixed sheave side of the belt groove in the variable speed pulley. The clutch means includes a pair of ring-shaped rotating members that are arranged such that they are concentrically opposed to each other and can rotate relative to each other; multiple rollers that are arranged along the circumferential direction of the rotating members between the two rotating members and whose rolling axis center is extending obliquely with a predetermined angle with respect to the radial direction of the rotating members; and a holding member for holding the multiple rollers such that the rollers are spaced away from each other and can roll. When the rotating members are pressed against the opposing rotating members, a connection state is established. One of the rotating members is provided on a sheave of the variable speed pulley such that the rotating member can rotate together with the sheave, and the other rotating member is provided such that it rotates relative to the one rotating member while being in contact with a side face of the V-belt. According to the above embodiment, and in the transmission-shift state of the continuously variable transmission, the movable sheave moves close to and away from the fixed sheave to open and close the variable speed pulley, so that the V-belt moves in the belt groove to the radial direction to change the belt diameter during wind in the belt groove. Thus, the continuously variable transmission is shifted. When this belt is moved onto the clutch means that is located on the groove side faces of the belt groove, the power transmission between the belt and the variable speed pulley is interrupted by the clutch means. At this time, the clutch means has one rotating member provided in the fixed sheave and the other rotating member that rotates while being in contact with a side face of the belt. Multiple rollers whose rolling axis center is extending obliquely with a predetermined angle with respect to the radial direction of the rotating members are arranged between the two rotating members. These rollers are spaced away from each other and rollably held by a holding member. Therefore, when the rotating members rotates while being pressed by the belt side, the rollers slide along the rotation direction of the rotating member by the relative rotation of the two rotating members while rolling in the state where each roller is held by a holding member. The rolling and the slide of the rollers can provide a stable rotation resistance. Therefore, the clutch means for performing the rolling and the slide of the rollers allow power transmission between the V-belt and the variable speed pulley to be interrupted smoothly. The clutch means is provided at least on a groove side face on the fixed sheave side of the belt groove of the variable speed pulley, and is built in the pulley, so that the configuration of the continuously variable transmission can be simple and compact. In addition, the clutch means has a simpler configuration than that of a centrifugal clutch having a weight and is inexpensive so that the cost of the continuously variable transmission can be reduced. In this case, it is preferable to provide the clutch means on each of the groove side faces on the sides of the fixed and the movable sheaves of the belt groove in the variable speed pulley, the two clutch means being opposed to each other. With this, the V-belt is moved to the position of the clutch means on the groove side face of the belt groove and is pushed up the rotating members of the clutch means both on the sides of the fixed and the movable sheaves and presses them. Thus, the power transmission between the variable speed pulley and the belt can be disconnected reliably and stably. The rotating shaft is an input shaft and the variable speed pulley is a drive pulley. The clutch means may be provided on the drive pulley side. Thus, a desirable variable speed pulley in which clutch means is provided can be embodied. In this case, in one embodiment, the present invention may include a driven pulley made of a variable speed pulley in which a fixed sheave and a movable sheave are supported on an output shaft that is parallel to the input shaft, and a belt groove is formed between the two sheaves; the V-belt wounded between the belt grooves of the drive and the driven pulleys; a weight roller that is provided on the side of the back face of the movable sheave of the drive pulley and is moved to the radially outer direction by an increase of a centrifugal force caused by rotation to move the movable sheave close to the fixed sheave so that the belt diameter during wind of the drive pulley is increased; and forcing means for forcing the movable sheave to move close to the fixed sheave that is provided on the side of the back face of the movable sheave of the driven pulley. Thus, as the input shaft and the drive pulley thereon rotates, the centrifugal force acts on the weight roller located on the side of the back face of the movable sheave of the drive pulley. When the rotation speed of the input shaft is low, the centrifugal force that acts on the weight rollers is smaller than the forcing force of the forcing means. Therefore, the forcing force of the forcing means forces the movable sheave of the driven pulley to be moved closer to the fixed sheave so that the driven pulley is closed. On the other hand, the movable sheave of the drive pulley is moved apart from the fixed sheave by the V-belt that has been moved by being pulled by the closed driven pulley so that the drive pulley is opened. The power transmission between this open drive pulley and the input shaft, or between the drive pulley and the V-belt is interrupted, and therefore the V-belt does not run although the input shaft rotates, and thus power is not transmitted between the input and the output shafts. When the rotation speed of the input shaft is increased from the non-connection state of the clutch, the centrifugal force acting on the weight roller is increased. When this centrifugal force becomes larger than the forcing force of the forcing means, the weight roller is moved to the radially outer direction to move the movable sheave close to the fixed sheave so that the drive pulley starts to be closed. When the closing operation of the drive pulley switches to the clutch connection state so that the power can be transmitted between the input shaft and the drive pulley or between the belt and the drive pulley. Thus, the V-belt rotates in accordance with the rotation of the input shaft and the drive pulley and the power is transmitted between the input shaft and the output shaft. In this state of power transmission by the belt, when the rotation speed of the input shaft is further increased and the centrifugal force that acts on the weight roller is increased, the movable sheave of the drive pulley is moved further closer to the fixed sheave, so that the drive pulley is changed to the closing direction. The V-belt that has been moved by being pulled by the closed drive pulley forces the movable sheaves of the driven pulley to be moved apart from the fixed sheave to open the driven pulley. Thus the transmission gear ratio is increased so that the transmission is continuously changed from the low speed state to the high speed state. Hence, this embodiment can provide the same effect as above. Spring means for forcing the movable sheave of the drive pulley to move away from the fixed sheave against the weight of the weight roller is provided so that the V-belt is maintained on the clutch means of the drive pulley when the V-belt is located on the clutch means. Thus, the movable sheave is forced to move away from the fixed sheave against the weight of the weight rollers when the V-belt is located on the clutch means of the drive pulley. As a result, the V-belt is maintained stably on the clutch means with no fluctuation due to the weight of the weight rollers. The present invention provides a vehicle provided with the above-described continuously variable transmission. This vehicle is preferably a motorbike. Thus, the continuously variable transmission of the present invention can be applied effectively. This and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view showing an enlarged primary part of a continuously variable transmission of one example of the present invention. Figure 2 is a cross-sectional view showing the entire configuration of the continuously variable transmission. Figure 3 is an exploded perspective view of a clutch mechanism. Figure 4 is a front view showing rollers held by a holding plate. Figure 5 is a view for illustrating the operation of the clutch mechanism with a development of the plate. DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention will be described by way of examples with reference to the accompanying drawings. Figure 2 is a belt type continuously variable transmission T according to an example of the present invention. The continuously variable transmission T is mounted on a motorbike (autobike) as a vehicle. More specifically, the continuously variable transmission T is provided between an on-board engine and a rear wheel as a driving wheel (both not shown) in a motorbike, that is, in the middle of a power transmission path for transmitting the rotation power of the engine to the rear wheel. The above-described continuously variable transmission T has a built-in clutch, and includes a left case 1a and a left case 1 that is divided by the left case 1a. In a front portion of the left case 1a , a crankshaft 2 of an engine horizontally extending as an input shaft is supported rotatably by bearings 3, and the head (output portion) of the crankshaft 2 extends between the left and right cases 1a and 1b. In a rear portion of the case 1, an output shaft 5 horizontally extending parallel to the head of the crankshaft 2 with an interval in the rear of the head of the crankshaft 2 is rotatably supported by bearings 6 and 7 between the left and the right cases 1a and 1b. A drive gear 8 is formed integrally with the output shaft 5 between the left and the right cases 1a and 1b. The drive gear 8 is driven-coupled to a driven gear on the wheel shaft of the rear wheel, although not shown. A variable speed pulley mechanism 10 for driven-coupling the head of the crankshaft 2 (input shaft) and the output shaft 5 with a V-belt 21 in transmission variable manner is housed in the case 1 (left and right cases 1a and 1b ). The variable speed pulley mechanism 10 includes a drive pulley 11 made of a variable speed pulley provided on the crankshaft 2 . The drive pulley 11 includes a flange-shaped fixed sheave 12 and a flange-shaped movable sheave 13 . The fixed sheave 12 is coupled onto the crankshaft 2 in a boss portion 12a in such a manner that it can rotate together with the crankshaft 2 and cannot be slid thereon. The movable sheave 13 is supported in the bass portion 12a (crankshaft 2 ) of the fixed sheave 12 in such a manner that it is opposed to the fixed sheave 12 from the right side and can be slid and cannot be rotated relatively in a bass portion 13a. A belt groove 14 having an approximately V shape is formed between the sheaves 12 and 13 . On the other hand, a driven pulley 16 made of a variable speed pulley having an approximately the same diameter as that of the drive pulley 11 is provided on the output shaft 5. The driven pulley 16 has the same configuration as that of the drive pulley 11 and includes a flange-shaped fixed sheave 17 and a flange-shaped movable sheave 18 . The fixed sheave 17 is supported on the output shaft 5 in a boss portion 17a in such a manner that it can rotate together with the output shaft 5 and cannot be slid thereon. The movable sheave 18 is supported in the bass portion 17a (output shaft 5 ) of the fixed sheave 17 in such a manner that it is opposed to the fixed sheave 17 from the left side, that is, in the direction opposite to the opposing direction of the movable sheave 13 to the fixed sheave 12 in the drive pulley 11, and can be slid and cannot be rotated relatively in a bass portion 18a. A belt groove 19 having an approximately V shape is formed between the sheaves 17 and 18. A V-belt 21 is wounded between the belt groove 14 of the drive pulley 11 and the belt groove 19 of the driven pulley 16 , and the belt diameter during wind of the pulleys 11 and 16 are changed by moving the movable sheaves 13 and 18 close to and away from the fixed sheaves 12 and 17 of the pulleys 11 and 16 , respectively. For example, when the movable sheave 13 of the drive pulley 11 is moved close to the fixed sheave 12 , and the movable sheave 18 of the driven pulley 16 is moved apart from the fixed sheave 17 , then the belt diameter during wind of the drive pulley 11 is larger than that of the driven pulley 16 , so that the rotation of the crankshaft 2 is transmitted to the output shaft 5 in an increased speed, which leads to a high speed state (Hi state). On the other hand, when the movable sheave 13 of the drive pulley 11 is moved apart from the fixed sheave 12 , and the movable sheave 18 of the driven pulley 16 is moved apart from the fixed sheave 17 , then the belt diameter during wind of the drive pulley 11 is smaller and the belt diameter during wind of the driven pulley 16 is larger, so that the rotation of the crankshaft 2 is transmitted to the output shaft 5 in a decreased speed, which leads to a low speed state (Lo state). A compression spring 23 as forcing means for forcing the movable sheave 18 to be close to the fixed sheave 17 is provided on the side of the back face of the movable sheave 18 of the driven pulley 16 . In other words, a flange-shaped spring receiving member 24 is integrally provided on the left end of the boss portion 17a of the fixed sheave 17 , and the compression spring 23 is provided between the spring receiving member 24 and the back face of the movable sheave 18 while being contracted in the circumference of the boss portion 18a of the movable sheave 18 , and the spring force of the compression spring 23 in the elongation direction forces the movable sheave 18 to move toward the fixed sheave 17 so that the driven pulley 16 is closed. At the same time, the drive pulley 11 is forced to the opening direction by pulling the V-belt 21 toward the driven pulley 16 by forcing the driven pulley 16 to be closed. In the state where the driven pulley 16 is closed to the highest extent (the state shown in Figure 2 ), the boss portion 18a of the movable sheave 18 is in contact with the fixed sheave 17 , and there is no belt tension. On the other hand, a centrifugal weight mechanism 26 is provided on the side of the back face of the movable sheave 13 of the drive pulley 11 . The centrifugal weight mechanism 26 has a guide plate 27 whose inner end is joined and fixed onto the crankshaft 2 on the right end of the boss portion 12a of the fixed sheave 12 of the drive pulley 11 . The guide plate 27 is a disk-shaped plate that is tapered and inclined toward the movable sheave 13 (left side) toward the radially outer direction. The back face of the movable sheave 13 is tapered toward the guide plate 27 (right side) toward the radially outer direction, substantially in the same manner as the groove side face 14b of the belt groove 14 on the side of the movable sheave, which is the surface of the movable sheave 13 . A plurality of weight rollers 28 (only one is shown in the drawings) is arranged such that they are spaced away from each other in the circumference direction and can roll in the radial direction while sandwiched by the back face of the movable sheave 13 and the guide plate 27. The centrifugal force caused by the rotation of the drive pulley 11 (crankshaft 2 ) acts on each weight roller 28 so that an increase in the centrifugal force drives the weight rollers 28 to roll along the guide plate 27 on the radially outer direction while being sandwiched by the back face of the movable sheave 13 and the guide plate 27 . Thus, the movable sheave 13 of the drive pulley 11 is moved close to the fixed sheave 12 against the forcing force of the compression spring 23 on the side of the driven pulley 16 , so that the belt diameter during wind of the drive pulley 11 can be increased. The present invention is characterized in that clutch mechanisms 31 and 31 are buried, opposing to each other, on the shaft line direction of the drive pulley 11 on the groove side face 14a on the side of the fixed sheave and the groove side face 14b on the side of the movable sheave in the bottom of the belt groove 14 of the drive pulley 11 . The clutch mechanisms 31 and 31 disconnect the power transmission between the V-belt 21 and the drive pulley 11 so as to block the V-belt 21 from operating together with the fixed and the movable sheaves 12 and 13 while the V-belt 21 is in contact with them at its sides. In other words, ring grooves 32 and 32 having the same diameter that are obtained by recessing the groove side faces 14a and 14b concentrically with the fixed and the movable sheaves 12 and 13, respectively, are formed on the groove side faces 14a and 14b on the sides of the fixed and the movable sheaves in the bottom of the belt groove 14 . The clutch mechanism 31 is housed and fixed in each ring groove 32 . The two clutch mechanisms 31 and 31 are identical and, as shown in Figure 3 , includes a pair of rotating members of a fixed plate 33 and a rotating plate 34 , multiple rollers 35 , ... arranged between the fixed and the rotating plates 33 and 34 , and a holding plate 36 (holding member). The fixed plate 33 and the rotating plate 34 are concentrically opposed to each other and can rotate relative to each other. When the rotating plate 34 is pressed against the opposing fixed plate 33 , a connection state is established (the clutch is ON). The fixed plate 33 is a disk ring and the surface and the back surface of the fixed plate 33 are planes orthogonal to the shaft line direction of the drive pulley 11 (crankshaft 2 ). The fixed plate 33 is fixed to the fixed sheave 12 in such a manner that the fixed plate 33 is concentric with the fixed sheave 12 and can rotate together with the fixed sheave 12 while being disposed in the bottom of the ring groove 32 . On the other hand, the rotating plate 34 is basically a disk ring having the same diameter as that of the fixed plate. The back surface of the rotating plate 34 opposing to the surface of the fixed plate 33 is a plane orthogonal to the shaft line of the drive pulley 11 , whereas the surface thereof is a tapered face 34a that is inclined at the same tapering angle as those of the groove side faces 14a and 14b of the belt groove 14 from the center to the outer circumference so as to approach the back surface. The rotating plate 34 is concentrically opposed to the fixed plate 33 on the side of the opening of the ring groove 32 , that is, on the side of the center in the belt groove width direction of the fixed plate 33 . The tapered face 34a of the surface of the rotating plate 34 is flush with the groove side faces 14a and 14b of the belt groove 14 , and the rotating plate 34 is rotated relative to the fixed plate 33 (sheaves 12 and 13 ) by the pressing force of the V-belt 21 while the V-belt 21 in the belt groove 14 is pushed up and is in contact with the tapered face 34a of the surface of the rotating plate 34 at the side faces thereof. The multiple rollers 35 , ... are arranged along the circumferential directions of the rotating plate 34 and the fixed plate 33 between the fixed plate 33 and the rotating plate 34, and the rolling axis center of each roller extends obliquely with a predetermined tilt angle  with respect to the radial direction of the rotating plate 34 and the fixed plate 33. The holding plate 36 is of a shape of a disk ring having a slightly smaller thickness of that of the outer diameter of the rollers 35 , and multiple holing holes 36a , 36a, ... that are rectangular through-holes for holding the rollers 35, one hole for one roller, with the tilt angle  unchanged are arranged in the circumference direction. The multiple rollers 35, 35, ... are held in the holding holes 36a, 36a, ... such that they are spaced away from each other in the circumferential direction and can roll. The rotating plate 34 and the holding plate 36 (roller 35 ) are interlocked to the ring groove 32 so as not to be detached therefrom by fixture means. In Figure 2 , a reference numeral 40 denotes a connecting rod of an engine coupled to the crankshaft 2 . A reference numeral 41 denotes a starter mechanism provided closer to the front portion of the left case 1a, and includes a driven shaft 43, an interlocking portion 45, a drive shaft 47 , and a kick lever 48 , and a coil spring 49 . The driven shaft 43 is supported rotatably in a concentrical manner with the crankshaft 2 and opposed to the head of the crankshaft 2 by the left case 1a, and has a driven gear 42. The interlocking portion 45 is attached to the head of the driven shaft 43 such that it can rotate together with the driven shaft 43 , and rotates the crankshaft 2 by interlocking to an interlocking portion 44 provided in the head of the crankshaft 2. The drive shaft 47 is supported parallel to the driven shaft 43 by the left case 1a and is provided with a drive gear 46 made of a sector gear engaged with the driven gear 42 of the driven shaft 43 . The kick lever 48 is attached to the end of the drive shaft 47 on the outer side of the case. The coil spring 49 forces the drive shaft 47 to rotate. A flange part 29 is formed at the outer peripheral edge on the back face of the moveable sheave 13 of the drive pulley 11 over the outer periphery of the guide plate 27 toward the opposite side to the fixed sheave 12 , integrally with the outer periphery of the back face of the guide plate 27 in the axial direction. Compression springs 30 are interposed between the flange part 29 and the back face of the outer periphery of the guide plate 27 . When the engine is in an idling state where the V-belt 24 rides on the clutch mechanisms 31 and 31 of the drive pulley 11 and the motorbike are stopping, the compression springs 30 force the movable sheave 13 of the drive pulley 11 to move away from the fixed sheave 12 against the weight of the weight rollers 28 , so that the V-belt 21 is maintained on the clutch mechanisms 31 and 31 . Thereby, no belt tension is caused. Therefore, in this example, when the crankshaft 2 is rotated during operation of the engine, the drive pulley 11 attached to the crankshaft 2 and the guide plate 27 of the centrifugal weight mechanism 26 are rotated integrally. As the crankshaft 2 and the drive pulley 11 are rotated, a centrifugal force acts on the weight rollers 28, 28, ... on the side of the back face of the movable sheave 13 of the drive pulley 11 . When the rotation speed of the engine is low, the centrifugal force that acts on the weight rollers 28 is smaller than the forcing force of the compression spring 23 of the driven pulley 16. Therefore, the forcing force of the compression spring 23 forces the movable sheave 18 of the driven pulley 16 to be moved closer to the fixed sheave 17 so that the driven pulley 16 is closed. On the other hand, the movable sheave 13 of the drive pulley 11 is moved apart from the fixed sheave 12 by the V-belt 21 that has been moved by being pulled by the closed driven pulley 16 so that the drive pulley 11 is opened. As shown by the solid line in Figure 1 , in the open drive pulley 11 , the V-belt 21 is pushed up the clutch mechanisms 31 and 31 on the groove side faces 14a and 14b on the left and right sides of the belt groove 14 in its bottom, and this push-up of the V-belt 21 on the clutch mechanisms 31 and 31 interrupts the power transmission between the drive pulley 11 and the V-belt 21 . This prevents the V-belt 21 from rotating together with the drive pulley 11 , although the crankshaft 2 and the drive pulley 11 are rotated. Thus, the rotation power of the crankshaft 2 is not transmitted to the output shaft 5 so that the motorbike does not run. At this time, each clutch mechanism 31 includes the fixed plate 33 fixed to the fixed sheave 12 of the drive pulley 11 and the rotating plate 34 that rotates in contact with the side face of the belt 21. The multiple rollers 35 , ... extending obliquely with a predetermined tilt angle  with respect to the radial direction of the rotating plate 34 are arranged between the fixed plate 33 and the rotating plate 34 , and these rollers 35 are spaced apart in the circumference direction and held rollably by the holding plate 36 . Therefore, when the rotating plate 34 is rotated while being pressed from the side face of the belt 21 , as shown in the development of Figure 5 , the relative rotation of the rotating plate 34 and the fixed plate 33 allows each roller 35 to slide along the rotation direction of the rotating plate 34 that is different from the rolling direction (direction shown in the virtual line of Figure 5) while rolling with being held in the holding plate 36 , and this rolling and slide of each roller 35 can provide stable rotation resistance. When the V-belt 21 is located on the clutch mechanisms 31 and 31 of the drive pulley 11 , the compression springs 30 force the movable sheave 13 to move away from the fixed sheave 12 against the weight of the weight rollers 28 to maintain the V-belt 21 on the clutch mechanisms 31 and 31 . Accordingly, the V-belt 21 is maintained stably on the clutch mechanisms 31 and 31 of the drive pulley 11 , with a result of no fluctuatoin due to the weight of the weight rollers 28 . When the rotation speed of the engine is increased from the non-connection state of the clutch (OFF state), the centrifugal force acting on each weight roller 28 is increased. When this centrifugal force becomes larger than the forcing force of the compression spring 23 , the weight rollers 28 are moved along the tapered surface of the guide plate 27 to the radially outer direction and this movement forces the movable sheave 13 to move closer to the fixed sheave 12 so that the drive pulley 11 started to be closed. As shown in the chain in Figure 1 , when the closing operation of the drive pulley 11 forces the belt 21 to move from the position of the clutch mechanisms 31 and 31 in the bottom of the belt groove 14 to the radially outer side to be in contact with the groove side faces 14a and 14b on the sides of the fixed and the movable sheaves, the clutch mechanism 31 is switched from the non-connection state to the connection state (ON state) so that the power can be transmitted between the belt 21 and the drive pulley 11 (low speed state), and the rotation of the crankshaft 2 and the drive pulley 11 rotates the belt 21 . The rotational movement of the belt 21 transmits the rotation power of the crankshaft 2 from the output shaft 5 to the rear wheel via the drive gear 8 and the driven gear and thus the motorbike starts to run. Thus, in the power transmission state between the belt 21 and the drive pulley 11 , a transmission-shift state can be achieved by varying the transmission gear ratio continuously between the low speed and the high speed in accordance with the increase and the decrease in the rotation speed of the engine. More specifically, when the rotation speed of the engine is increased and the centrifugal force acting on each weight roller 28 is increased, the weight roller 28 further moves to the radially outer direction so that the movable sheave 13 becomes closer to the fixed sheave 12 so that the drive pulley 11 is turned to be in the closing direction. The belt 21 that has been moved by being pulled by the drive pulley 11 in the closing direction forces the movable sheave 18 of the driven pulley 16 to move apart from the fixed sheave 17 so that the driven pulley 16 is open. Thus, the transmission gear ratio of the continuously variable transmission T is increased so that the continuously variable transmission T is shifted continuously from the low speed state to the high speed state. At the maximum speed state, as shown by the double dotted chain line in Figure 1 , the drive pulley 11 is opened to the maximum extent, whereas the driven pulley 16 is closed to the minimum extent. When the rotation speed of the engine is reduced, to the contrary to the above, the transmission gear ratio of the continuously variable transmission T is reduced so that the continuously variable transmission T is shifted continuously from the high speed state to the low speed state. For the state where the motorbike stops running, the opposite operation to the above returns the low speed state to the clutch non-connection state. Therefore, in this example, the clutch mechanism 31 for rolling and sliding the rollers 35 is provided in the drive pulley 11 , so that the power transmission between the belt 21 and the drive pulley 11 can be disconnected smoothly. In addition, the clutch mechanism 31 is provided in each of the groove side faces 14a and 14b on the sides of the fixed and the movable sheaves in the bottom of the belt groove 14 of the drive pulley 11, so that the power transmission between the drive pulley 11 and the belt 21 can be disconnected reliably and stably. Thus, the motorbike can start (or stop) smoothly. Furthermore, each clutch mechanism 31 is of a built-in pulley type in which it is provided in the groove side faces 14a and 14b on the side of the fixed and the movable sheaves of the belt groove 14 of the drive pulley 11 , and therefore the configuration of the continuously variable transmission T is simple and compact. Moreover, each clutch mechanism 31 has a simpler configuration than that of a centrifugal clutch having a weight and is inexpensive so that the cost of the continuously variable transmission T can be reduced. Other examples In the above example, the clutch mechanism 31 is provided in each of the groove side faces 14a and 14b on the sides of the fixed and the movable sheaves of the belt groove 14 of the drive pulley 11 . However, when the movable sheave 13 is rotated relative to the crankshaft, the clutch mechanism 31 can be provided only in the groove side face 14a on the side of the fixed sheave. In the above example, the clutch mechanism 31 is provided in the bottom of the belt groove 14. However, the clutch mechanism 31 is not necessarily positioned in the bottom of belt groove 14 , but the position can be changed with the transmission-shift pattern of the continuously variable transmission. Furthermore, in the above example, the fixed plate 33 as one rotating member of the clutch mechanism 31 is provided separately from each of the sheaves 12 and 13 of the drive pulley 11 . However, each of the sheaves 12 and 13 can constitute a rotating member itself, and can be used as the bottom of the ring groove 32 . In the above embodiment, the clutch mechanism 31 is provided on the side of the belt groove 14 . However, the clutch mechanism 31 can be provided so as to disconnect the power transmission between the crankshaft 2 (or may be output shaft) and the drive pulley 11 (or may be a driven pulley). For example, the fixed and the movable sheaves 12 and 13 of the drive pulley 11 (variable speed pulley) are supported rotatably on the crankshaft 2 (rotating shaft) and the fixed plate 33 of the clutch mechanism 31 is provided in the movable sheave 13 (or the fixed sheave 12 ) of the drive pulley 11 (separately from the sheave or integrally with the sheave by having it serve for the two functions). On the other hand, the rotating plate 34 is provided on the side of the crankshaft 2 , for example, provided in a member that rotates together with the crankshaft 2 , and the rotating plate 34 is pressed against the fixed plate 33 on the drive pulley 11 by the weight rollers 28 , so as to have the clutch mechanism 31 be in the connection state to perform power transmission between the crankshaft 2 and the drive pulley 11 . Furthermore, the clutch mechanism 31 is not necessarily those described above, but can be various types disclosed in the above proposed example (see Japanese Laid-Open Patent Publication No. 8-74843). Furthermore, in the above example, the continuously variable transmission T having the centrifugal weight mechanism 26 has been described. However, the present invention is not limited to such a continuously variable transmission, but can be applied to other types of continuously variable transmissions. In the above example, the continuously variable transmission T for motorbikes has been described. However, the present invention can be applied as continuously variable transmissions for other vehicles than motorbikes, such as vehicles for agriculture, lawn mower and golf carts, or continuously variable transmissions for other purposes. The embodiments disclosed in this application are to be considered in all respects as illustrative and not limiting. The scope of the invention is indicated by the appended claims rather than by the foregoing description.

Claims: A continuously variable transmission comprising a variable speed pulley having fixed and movable sheaves (12, 13) that are rotatably provided on a rotating shaft (2) and opposed to each other, in which a belt groove (14) is formed between the sheaves (12;13); and a V-belt (21) wounded in the belt groove (14) of the variable speed pulley, wherein transmission is shifted by changing a belt diameter during wind in the belt groove (14) by moving the movable sheave (13) close to and away from the fixed sheave (12) to open and close the variable speed pulley, characterized in that a clutch means (31) for disconnecting power transmission between the rotating shaft (2) and the variable speed pulley is provided, the clutch means (31) comprises: a pair of ring-shaped rotating members (33, 34) that are arranged such that they are concentrically opposed to each other and can rotate relative to each other; multiple rollers (35) that are arranged along a circumferential direction of the rotating members (33, 34) between the two rotating members (33, 34) and whose rolling axis center is extending obliquely with a predetermined angle with respect to a radial direction of the rotating members; and a holding member (36) for holding the multiple rollers (35) such that the rollers (35) are spaced away from each other and can roll, wherein when the rotating members (33, 34) are pressed against the opposing rotating members, a connection state is established, one of the rotating members (33, 34) is provided on one side of the variable speed pulley, and the other rotating member is provided on the rotating shaft (2). A continuously variable transmission comprising a variable speed pulley having fixed and movable sheaves (12, 13) that are provided on a rotating shaft (12) and opposed to each other, in which a belt groover (14) is formed between the sheaves; and a V-belt (21) wounded in the belt groove (14) of the variable speed pulley, wherein transmission is shifted by changing a belt diameter during wind in the belt groove (14) by moving the movable sheave (18) close to and away from the fixed sheave (17) to open and close the variable speed pulley. wherein clutch means (31) for disconnecting power transmission between the V-belt (21) and the variable speed pulley is provided at least on a groove side face on the fixed sheave side (17) of the belt groove (14) in the variable speed, characterized in that the clutch (31) means comprises: a pair of ring-shaped rotating members (33, 34) that are arranged such that they are concentrically opposed to each other and can rotate relative to each other; multiple rollers (35) that are arranged along a circumferential direction of the rotating members (34, 35) between the two rotating members (33, 34) and whose rolling axis center is extending obliquely with a predetermined angle with respect to a radial direction of the rotating members; and a holding member (36) for holding the multiple rollers (35) such that the rollers (35) are spaced away from each other and can roll, wherein when the rotating members (33, 34) are pressed against the opposing rotating members, a connection state is established, one of the rotating members (34) is provided on a sheave (12, 13) of the variable speed pulley such that the rotating member can rotate together with the sheave (12, 13), and the other rotating member is provided such that it rotates relative to the one rotating member while being in contact with a side face of the V-belt (21). The continuously variable transmission according to claim 2, wherein the clutch means (31) is provided in each groove side face on the sides of the fixed and movable sheaves (12, 13) of the V-belt (21) in the variable speed pulley, the two clutch means (31) being opposed to each other. The continuously variable transmission according to any one of claims 1 to 3, wherein the rotating shaft (2) is an input shaft and the variable speed pulley is a drive pulley, the clutch means (3) is provided on the drive pulley side. The continuously variable transmission according to claim 4, comprising: a driven pulley made of a variable speed pulley in which a fixed sheave (17) and a movable sheave (18) are supported on an output shaft (5) that is parallel to the input shaft (2), and a belt groove (14) is formed between the two sheaves (12, 13); the V-belt (21) wounded between the belt grooves (14) of the drive and the driven pulleys; a weight roller (28) that is provided on a side of a back face of the movable sheave (13) of the drive pulley and is moved to a radially outer direction by an increase of a centrifugal force caused by rotation to move the movable sheave (13) close to the fixed sheave (12) so that the belt diameter during wind of the drive pulley is increased; and forcing means for forcing the movable sheave (18) to move close to the fixed sheave (17) that is provided on a side of the back face of the movable sheave (18) of the driven pulley. The continuously variable transmission according to claim 5, comprising spring means (30) for forcing the movable sheave (13) of the drive pulley to move away from the fixed sheave (12) against the weight of the weight rollers so that the V-belt (21) is maintained on the clutch means (31) of the drive pulley when the V-belt (21) is located on the clutch means (31). A vehicle provided with one of the continuously variable transmissions according to claims 1 to 6. The vehicle according to claim 7, which is a motorbike.

Inventors: MIYATA HIROFUMI, MIYATA, HIROFUMI
Applicants: BANDO CHEMICAL IND, BANDO CHEMICAL INDUSTRIES, LTD.
Application year: 2001
Main classification: F16H55
IPC codes: F16H55, F16H9