JP4698339B2 - V belt type continuously variable transmission - Google Patents

Description

  The present invention relates to a V-belt type continuously variable transmission, and more particularly, to a driving mechanism for a pulley movable half.

  In the V-belt type continuously variable transmission, the pulley fixed half is fixed to the rotating shaft, and the pulley movable half is attached to the rotating shaft so as not to rotate relative to the rotating shaft and to move in the axial direction. The screw-type feed mechanism in the drive mechanism of the pulley movable half of the conventional V-belt type continuously variable transmission has an axially fixed side screw portion held on the rotating shaft via a bearing and cannot be rotated on the transmission case. An axially movable side screw portion that is attached so as not to move in the direction and is screwed to the outer peripheral screw of the axially fixed side screw portion is attached to the pulley movable half body through a bearing so as to be relatively rotatable and axially movable. The motor is driven to rotate through a reduction gear mechanism. When the motor is started, the axially movable side screw portion moves in the axial direction while rotating, and moves the pulley movable half in the axial direction (see, for example, Patent Document 1).

  In the above configuration, the axially movable side screw part itself meshed with the final stage gear of the reduction gear mechanism via an integral gear moves in the axial direction while being rotationally driven. Therefore, the final stage gear itself of the reduction gear mechanism is axially It is necessary to have a long gear. For this reason, the transmission mechanism has been increased in size.

Japanese Patent No. 3099023 (FIG. 5).

  The present invention seeks to provide a V-belt continuously variable transmission that can be miniaturized by improving the drive mechanism of the pulley movable half body.

The present invention solves the above-mentioned problems, and the invention according to claim 1 is directed to a pulley fixing half that is fixedly supported on a rotating shaft, and the pulley fixing half facing the rotating shaft on the rotating shaft. In a V-belt type continuously variable transmission comprising a pulley movable half that is supported so as to be movable in the axial direction in a state in which rotation with respect to the pulley is prevented, and clamps the belt in cooperation with the pulley fixed half. includes a threaded portion, the axial movement are integrally held in the axial direction relative immovably mounted ball bearings are relatively rotatably held with respect to the rotation axis in a state of being blocked with respect to the axis of rotation, the electric motor An axially fixed side screw assembly that is rotationally driven through a reduction gear mechanism from
An axially movable side screw assembly that includes an axially movable side threaded portion that fits into the axially fixed side threaded portion and that is held movably in the rotational axis direction while being prevented from rotating with respect to the transmission case. A screw-type feed mechanism comprising: a V-belt type, wherein an axially movable side screw assembly of the screw-type feed mechanism is attached to the pulley movable half so as not to be axially movable and relatively rotatable. It is a continuously variable transmission.

According to a second aspect of the present invention, in the V-belt type continuously variable transmission according to the first aspect, the axially movable side screw portion is relatively rotated via a bearing member on the cylindrical shaft portion of the pulley movable half body. possible and while being supported in the axial direction relative movement unsaturated ability, said axial movable threaded portion and the said bearing member is provided on the inside in the axial direction fixed side thread portion on the cylindrical shaft portion of the pulley movable-half It is characterized by that.

  According to a third aspect of the present invention, in the V-belt continuously variable transmission according to the first aspect, the input gear of the axially fixed side screw assembly in the screw-type feed mechanism and the umbrella-shaped portion of the pulley movable half body One of the reduction gears is arranged in the gap between them.

  In the invention of claim 1, the input gear of the screw type feed mechanism that is driven by meshing with the final gear of the reduction gear mechanism is a gear of the axially fixed side screw assembly, and this does not move in the axial direction. The width of the final gear of the reduction gear mechanism can be reduced, and the transmission can be reduced in size.

  According to the invention of claim 2, since the axially movable side screw part and the bearing member are arranged using the inner side of the width of the axially fixed side screw part, the transmission can be miniaturized by effectively utilizing dead space. it can.

  According to the invention of claim 3, since one of the reduction gears is arranged by effectively utilizing the dead space between the input gear of the axially fixed side screw assembly and the umbrella-shaped portion of the pulley movable half body, the transmission can be reduced in size. Can be

  FIG. 1 is a side view of a power unit 1 according to the present invention. This power unit is mounted on a motorcycle, and is supported by an overhead valve type four-stroke cycle two-cylinder water-cooled internal combustion engine 2 fixed to the vehicle and swingable up and down around a crankshaft 11. The transmission 3, the rear wheel support 4 and the rear wheel are integrated. An arrow F points to the front of the internal combustion engine 2.

  The internal combustion engine 2 of the power unit 1 includes a portion surrounded by a crankcase 6, a cylinder block 7, a cylinder head 8, and a cylinder head cover 9, and a cylinder oriented slightly upward at the front end of the crankcase 6. A block 7 is coupled, a cylinder head 8 is coupled to the front end of the cylinder block 7, and a cylinder head cover 9 is coupled to the front end of the cylinder head 8. A rear wheel shaft 60 is incorporated in the rear wheel support portion 4 and transmits the power of the internal combustion engine to the rear wheels.

  FIG. 2 is a developed cross-sectional view of the AA cross section, the BB cross section, and the CC cross section of FIG. 1 drawn on one plane. The crankcase 6 includes a left crankcase 6L and a right crankcase 6R. The crankshaft 11 is rotatably supported by the journal bearing portions 10L and 10R of the left and right crankcases 6L and 6R. On the other hand, a piston 13 is slidably fitted in a cylinder hole 12 formed in the cylinder block 7. Both ends of the connecting rod 16 are pivotally supported by the crankshaft 11 and the piston 13 via the crankpin 14 and the piston pin 15, respectively. A combustion chamber 20 is formed on the bottom surface of the cylinder head 8 facing the end surface of the piston 13, a spark plug 21 is mounted from the top of the cylinder head cover 9, and its tip faces the combustion chamber 20.

  The cylinder head 8 is formed with an intake port and an exhaust port connected to the combustion chamber 20, and the intake valve and the exhaust valve are slidably fitted into the cylinder head 8. FIG. 2 shows an exhaust valve 27 for the right combustion chamber.

  In FIG. 2, a camshaft 28 is supported between the cylinder head 8 and the cylinder head cover 9 in parallel with the crankshaft 11, and the intake valve and the exhaust valve are driven to open and close by the cam provided on the camshaft 28. FIG. 2 shows an exhaust cam 29. The camshaft 28 is rotationally driven by an endless chain 32 wound between a drive sprocket 30 provided at the right portion of the crankshaft 11 and a driven sprocket 31 provided at the right end of the camshaft 28.

  A right crankcase cover 33 is provided outside the right crankcase 6R, and a generator 36 is constituted by a stator 34 fixed to the inner surface thereof and a rotor 35 fixed to the crankshaft 11 and surrounding the stator 34. Yes. A driven gear 37 provided adjacent to the generator 36 is a gear for receiving a rotational drive from a starter motor (not shown).

  The transmission case 38 that houses the transmission 3 in the power unit 1 includes a right transmission case 38R, a left transmission case 38L, and a partition wall 38S. The right transmission case 38R is rotatably supported on the left and right of the crankcase 6. On the left side of the crankcase, the left crankcase 6L is rotatably supported by a ball bearing 40 held by a support metal 39 attached by a bolt 22, and on the right side of the crankcase, it is attached to the right crankcase cover 33. It is supported rotatably by connection hardware 43A, 43B supported by a roller bearing 42 held by the support hardware 41. The connection hardware 43A and 43B are integrated with bolts. A transmission case cover 23 is provided outside the left transmission case 38L.

  Both the left transmission case 38L and the partition wall 38S are coupled to the right transmission case 38R by bolts. The rear end portion of the transmission case 38 of the transmission 3 is a rear wheel support portion 4. The transmission 3 includes a V-belt type continuously variable transmission 45 and a gear reducer 46. The V-belt type continuously variable transmission 45 has a front half portion provided between the left transmission case 38L and the right transmission case 38R, and a second half portion provided between the left transmission case 38L and the partition wall 38S. The speed reducer 46 is provided between the partition wall 38S and the right transmission case 38R.

  The drive shaft of the V-belt continuously variable transmission 45 is the crankshaft 11 itself, and a drive pulley 47 of the V-belt continuously variable transmission 45 is provided at the left end of the crankshaft 11. The drive pulley 47 includes a fixed half 48 and a movable half 49. The driven shaft 50 of the V-belt type continuously variable transmission 45 is rotatably supported by the left transmission case 38L, the partition wall 38S, and the right transmission case 38R. A driven pulley 52 of a V-belt type continuously variable transmission 45 is provided on the driven shaft 50 via a centrifugal clutch 51. The driven pulley 52 includes a fixed half 53 and a movable half 54. An endless V-belt 55 is stretched between the driving pulley 47 and the driven pulley 52, and the rotation of the driving pulley 47 is transmitted to the driven pulley 52. When the rotational speed of the driven pulley 52 exceeds a predetermined rotational speed, the centrifugal clutch 51 provided between the driven pulley 52 and the driven shaft 50 is connected, and the driven shaft 50 starts to rotate.

  The gear reducer 46 is constituted by a gear group provided on three rotating shafts. The first shaft is the right half of the driven shaft 50 of the V-belt type continuously variable transmission 45 supported by the right transmission case 38R and the partition wall 38S, and a small diameter gear 56 is formed. The second shaft is an intermediate shaft 57 that is rotatably supported by the right transmission case 38R and the partition wall 38S, and the large-diameter gear 58 that meshes with the small-diameter gear 56 of the driven shaft 50 is integrally fitted. In addition, a small diameter gear 59 is formed adjacent thereto. The third shaft is a rear wheel shaft 60 that is rotatably supported by a partition wall 38S, a right transmission case 38R, and an arm 62 coupled to the connection hardware 43A. A large-diameter gear 61 that meshes with the small-diameter gear 59 of the intermediate shaft 57 is fitted to the rear wheel shaft 60. With this configuration, the torque of the driven shaft 50 is decelerated through the reduction gear group and transmitted to the rear wheel shaft 60. The rear wheel 5 is integrally fixed to the rear wheel shaft 60.

  FIG. 3 is an enlarged cross-sectional view showing a state where the drive pulley 47 and its peripheral members are assembled to the crankshaft 11. The drive pulley 47 includes a drive pulley fixed half 48 and a drive pulley movable half 49. The left half of the crankshaft 11 is formed with a first small diameter portion 11A delimited by a step 11a and a step 11b, and a second small diameter portion 11B delimited by a step 11b and a crankshaft end surface portion 11c. . A spline 11d is provided at the end of the first small diameter portion 11A, and a spline 11e is provided at the end of the second small diameter portion 11B.

  The inner ring of the ball bearing 63, the first support sleeve 64, and the guide sleeve 65 are fitted into the first small diameter portion 11A, and the second support sleeve 66 and the driving pulley are fixed to the second small diameter portion 11B. A half 48 is fitted. The sleeves 64, 65 and 66 are made of steel, and the driving pulley fixing half 48 is made of aluminum. Each of the above members is fastened to the screw hole at the end of the crankshaft 11 with a bolt 68 screwed through a washer 67, and is fixed so as not to move in the direction of the crankshaft 11. Of the above members, the guide sleeve 65 is fitted into the spline 11d of the first small-diameter portion 11A via the spline 65a on the inside thereof. The drive pulley fixing half 48 is fitted to the spline 11e of the second small diameter portion 11B via a spline 48a inside the center hole. Therefore, these members are fixed so as not to rotate relative to the crankshaft 11. The driving pulley fixing half 48 rotates with the crankshaft 11.

  The drive pulley movable half 49 includes an umbrella-shaped portion 49A that faces the fixed half, and a cylindrical portion 49B that surrounds the sleeves 64, 65, 66 and is integrally formed with the umbrella-shaped portion 49A. Yes. The umbrella portion 49A is made of an aluminum alloy, and the tubular portion 49B is made of steel. The umbrella-shaped portion 49A is integrally coupled to the flange portion of the cylindrical portion 49B by a rivet 44. A projecting spline 49Ba projecting inward is formed on the inner side of the cylindrical portion 49B of the driving pulley movable half 49, and is fitted to an outer spline 65b formed on the outer periphery of the guide sleeve 65. Since the outer spline 65b of the guide sleeve 65 is a long spline in the axial direction, the protruding spline 49Ba can slide in the axial direction in the guide groove. Accordingly, the drive pulley movable half 49 cannot be rotated relative to the crankshaft 11, but is held so as to be movable in the axial direction. The drive pulley movable half 49 receives torque from the crankshaft 11 and rotates together with the crankshaft 11 by the splines 11d, 65a, 65b, and 49Ba. Grease is applied to the groove of the outer spline 65b of the guide sleeve 65 to smooth the sliding of the protruding spline 49Ba of the movable half cylindrical portion 49B. Seals 69 are provided at both ends of the movable half cylindrical portion 49B for preventing leakage of the grease and preventing intrusion of dust.

  4 is an enlarged cross-sectional view of only the shaft portion (excluding the ball bearing and the like) of the IV-IV cross section of FIG. The spline 11d of the crankshaft 11 and the inner spline 65a of the guide sleeve 65 meshing with each other are involute splines, and the projecting spline 49Ba meshing with the outer spline 65b of the guide sleeve 65 is also an involute spline. A gap 70 is provided between the outer peripheral surface of the guide sleeve and the inner peripheral surface of the movable half cylindrical shaft portion 49B in order to enable movement of air and grease accompanying the movement of the protruding spline.

  In FIG. 3, a cylindrical ball bearing outer ring holding member 75 holds the outer ring of the ball bearing 63 attached to the crankshaft 11 so as not to move in the axial direction. A female thread cylindrical member 76 is integrated with the flange portion 75a on the outer periphery of the ball bearing outer ring holding member 75 by welding. An annular gear 77 is coupled to a flange portion 76 a on the outer periphery of the female screw cylindrical member 76 by a bolt 78. The ball bearing outer ring holding member 75, the female screw cylindrical member 76, and the annular gear 77 are integrated to form a female screw assembly 79, supported by the crankshaft 11 by the ball bearing 63, and in a state in which axial movement is impossible. Rotation independent of the axis 11 can be performed. The annular gear 77 of the female screw assembly 79 is rotationally driven by a small-diameter gear 102 of a second intermediate gear 104 that forms part of a transmission actuator 90 described later.

  An inner ring of a ball bearing 72 is mounted on the outer periphery of the cylindrical portion 49B of the movable half 49 of the driving pulley so as not to be relatively movable in the axial direction, and a male screw cylindrical member 80 is integrated with the outer ring of the ball bearing 72 on the inner periphery thereof. Is holding. The outer thread portion of the male thread cylindrical member 80 is engaged with the inner thread portion of the female thread cylindrical member. An anti-rotation member 81 is coupled to the flange portion 80 a at the end of the male screw cylindrical member 80 by a bolt 82. The male screw cylindrical member 80, the rotation preventing member 81, and the bolt 82 are integrated to form a male screw assembly 83. The protrusions 81b formed on both sides of the rotation stopper shaft 81a of the rotation stopper 81 are engaged with the rotation guide rail 84 provided on the right transmission case 38R shown in FIG. 6 (side view). is doing. As a result, when the female screw assembly 79 rotates, the male screw assembly 83 can only move in the direction of the crankshaft axis while preventing rotation around the crankshaft. The female screw assembly 79 and the male screw assembly 83 constitute a screw type feed mechanism 89.

  A front stopper 81 c is integrally formed on the arm portion of the rotation preventing member 81. This is for detecting the limit of the backward movement of the male screw assembly 83. A rear stopper 85 is attached to the rear end of the shaft portion 81 a of the rotation preventing member 81 with a bolt 86. This is for detecting the limit of forward movement of the male screw assembly 83. The anti-rotation member 81 and the anti-rotation guide rail 84 (FIG. 6) constitute an anti-rotation mechanism 88 (FIG. 6).

  The anti-rotation member 81 is formed with an extension 81d outside the shaft portion. The extension 81d is in contact with the tip of the bar-like member protruding from the end of the stroke sensor 87 for detecting the current position of the movable half. The stroke detection is performed by detecting the displacement of the rod-shaped member pushed out from the end of the stroke sensor 87 by a spring. The peripheral part of the rod-shaped member is covered with rubber bellows. The base of the stroke sensor 87 is connected to the right transmission case 38R.

  FIG. 5 is a developed sectional view of the front half of the transmission 3. FIG. 6 is an arrangement diagram of gears and the like when the front half of the transmission is viewed from the side. The female screw assembly 79 is rotationally driven by a speed change actuator 90. The speed change actuator 90 includes an electric motor 91 and a gear reduction mechanism 92. The rotation of the electric motor 91 is automatically controlled according to the vehicle speed, the throttle opening, and the rotational speed of the internal combustion engine. A reduction gear case 93 is attached to the right transmission case 38R. This case includes a right case member 93R, a left case member 93L, and an end case member 93E. A reduction gear chamber 94 is formed in a portion sandwiched between these case members. An electric motor 91 is attached to the right case member 93R of the reduction gear case 93 via the attachment plate 95, and a pinion 96 engraved on the rotation shaft of the motor enters the reduction gear chamber 94.

  A first intermediate gear 99 in which a large-diameter gear 97 meshing with the pinion 96 and a small-diameter gear 98 adjacent to the pinion 96 are integrally formed is rotatably supported by a reduction gear case 93 via a ball bearing 100.

  A second intermediate gear 104 in which a large-diameter gear 101 that meshes with the small-diameter gear 98 and a small-diameter gear 102 that is integrally adjacent to the small-diameter gear 98 are integrally fitted with the rotary shaft 103 is mounted on the reduction gear case 93. The bearing 105 is rotatably supported. The annular gear 77 of the female screw assembly 79 is meshed with the small-diameter gear 102.

  When the electric motor 91 rotates in the positive direction according to the control command, power is transmitted via the first and second intermediate gears 99 and 104, the female screw assembly 79 rotates, and the screw of the female screw cylindrical member 76 is rotated. The threaded portion of the male screw cylindrical member 80 of the non-rotatable male screw assembly 83 meshing with the portion receives thrust in the crankshaft direction from the threaded portion of the female screw cylindrical member 76, and the male screw assembly 83 is Move in the axial direction. The thrust received by the threaded portion of the male threaded cylindrical member 80 is transmitted to the movable half via the ball bearing 72, the drive pulley movable half 49 moves in the direction of the crankshaft axis, and the drive pulley fixed half 48 The interval is narrowed and the V-belt is moved in the outer circumferential direction. When the electric motor 91 rotates in the reverse direction in accordance with the control command, the interval between the drive pulley fixed half 48 and the drive pulley movable half 49 is widened by the reverse process, and the V-belt moves in the center direction. .

  FIG. 7 is a developed sectional view of the rear half of the transmission 3. The driven pulley 52 includes a driven pulley fixed half 53 and a driven pulley movable half 54. The driven pulley fixing half 53 includes an aluminum umbrella-shaped portion 53A and a steel tubular portion 53B. The driven pulley movable half 54 is also composed of an aluminum umbrella-shaped portion 54A and a steel tubular portion 54B. The umbrella-shaped portion of the fixed half 53 is fastened to the end of the cylindrical portion by a bolt 147, and the umbrella-shaped portion of the movable half 54 is integrally formed at the end of the cylindrical portion by casting.

  The driven shaft 50 is provided with step portions 50a, 50b and 50c. The cylindrical portion 53B of the driven pulley fixing half 53 is rotatable with respect to the driven shaft 50 by the ball bearing 110 provided on the outer periphery of the step portion 50a and the roller bearing 111 provided on the outer periphery of the step portion 50b. It is supported.

  A cylindrical part 54B of the movable half is slidably fitted on the outer periphery of the cylindrical part 53B of the fixed half. Pins 112 are implanted at four locations on the outer periphery of the cylindrical portion 53B of the fixed half body. The cylindrical portion 54B of the movable half body is provided with cam grooves 113 that penetrate in the radial direction of the cylindrical portion 54B and extend at an inclination with respect to the axial direction at four locations in the circumferential direction. The head of the pin 112 is inserted. As a result, the driven pulley movable half 54 is restricted by the pin 112 and can be moved relative to the driven pulley fixed half 53 in the axial direction, and the circumferential relative movement corresponding to the angle of the cam groove can be performed. Is possible.

  A cylindrical member 114 is fixed to the outer periphery of the cylindrical portion 54B of the driven pulley movable half 54 so as not to move in the axial direction, and covers the cam groove 113 of the cylindrical portion 54B. In order to assist the sliding of the driven pulley movable half 54 restricted by the pin 112, grease is applied to the cam groove 113, and seal materials for preventing oil leakage are provided inside both ends of the cylindrical member 114. It is provided. An inner ring of the ball bearing 115 is held on the outer periphery of the right end of the cylindrical member 114. An annular member 116 that abuts on the outer ring of the ball bearing 115 is provided.

  The inner ring of the ball bearing 117 is fixed to the stepped portion on the outer periphery of the left end of the cylindrical portion 53B of the driven pulley fixing half 53 by a nut 118. A male thread cylindrical member 120 is fixed to the outer ring of the ball bearing 117 so as not to move in the axial direction. The rotation of the male thread cylindrical member 120 is blocked by the ball bearing 117 with respect to the driven pulley 53. An anti-rotation member 121 is fixed to the male screw cylindrical member 120, and its end is fixed to the transmission case 38 (not shown). Therefore, the male screw cylindrical member 120 can remain stationary with respect to the transmission case 38 independently of the driven shaft 50 and the driven pulley 52 in both the axial direction and the rotational direction.

  The male screw cylindrical member 122 covers the male screw portion of the male screw cylindrical member 120 in a screwed state. An annular gear 123 is fixed to the flange portion 122 a of the female screw cylindrical member 122 by a bolt 124. A female screw assembly 125 is formed by the female screw cylindrical member 122, the annular gear 123, and the bolt 124.

The annular gear 123 is driven and rotated by a small-diameter gear 142 of a second intermediate gear 144 described later, and the female screw portion of the female screw cylindrical member 122 receives thrust from the male screw portion of the fixed male screw cylindrical member 120. The female screw cylindrical member 122 is driven in the axial direction while rotating. A disc spring 126 is interposed between the end of the female screw cylindrical member 122 and the annular member 116 fixed to the outer periphery of the ball bearing 115. Accordingly, the driven pulley movable half 54 is driven in the axial direction via the disc spring 126, the annular member 116, the ball bearing 115, and the cylindrical member 114 by the axial movement of the female screw cylindrical member 122. The male screw cylindrical member 120 and the female screw assembly 125 constitute a screw type feed mechanism 127.

  The female screw assembly 125 is rotationally driven by a speed change actuator 130. The speed change actuator 130 includes an electric motor 131 and a gear reduction mechanism 132. The rotation of the electric motor 131 is automatically controlled according to the vehicle speed, the throttle opening, and the rotational speed of the internal combustion engine. The strain of the disc spring 126 is measured to detect the pressing force of the driven pulley movable half against the V-belt and fed back for control.

  A reduction gear case 133 is attached to the left transmission case 38L, and a reduction gear chamber 134 is formed. The electric motor 131 is attached to the reduction gear case 133 via the attachment plate 135, and a pinion 136 engraved on the rotation shaft of the motor enters the reduction gear chamber 134. A first intermediate gear 139 in which a large-diameter gear 137 meshing with the pinion 136 and a small-diameter gear 138 adjacent thereto is integrally formed is rotated via a ball bearing 140 to the left transmission case 38L and the reduction gear case 133. Supported as possible.

  A second intermediate gear 144 in which a large-diameter gear 141 that meshes with the small-diameter gear 138 and a small-diameter gear 142 that is integrally adjacent to the large-diameter gear 138 are fitted into the rotary shaft 143 is integrated into the left transmission case 38L. And a reduction gear case 133 is rotatably supported via a ball bearing 145. The small-diameter gear 142 is a gear having a long axial dimension, and can be engaged with the annular gear 123 of the female screw assembly 125 at an arbitrary position in the axial direction.

  FIG. 8 is an arrangement diagram of gears and the like when the rear half of the transmission is viewed from the side. In the state of FIG. 7, when the electric motor 131 rotates in the positive direction according to the control command, power is transmitted via the first and second intermediate gears 139 and 144 and meshes with the threaded portion of the male threaded cylindrical member 120. The internal thread assembly 125 rotates, the internal thread assembly 125 itself moves in the axial direction of the driven shaft 50, and the driven pulley is movable via the disc spring 126, the annular member 116, the ball bearing 115, and the cylindrical member 114. The half body 54 is pushed, the space | interval with the drive pulley fixed half body 53 is narrowed, and a V belt is moved to an outer peripheral direction. When the electric motor 131 rotates in the reverse direction in response to the control command, the interval between the driven pulley fixed half 53 and the driven pulley movable half 54 is increased by the reverse process to the above, and the V-belt moves in the center direction. . The left-side stopper 121a of the female screw assembly is provided at the other end of the anti-rotation member 121, and detects the limit of the leftward movement of the female screw assembly.

  An inner rotating member 51A of the centrifugal clutch 51 is fixed with a bolt 147 to the right end surface of the driven pulley fixing half. The outer rotating member 51B of the centrifugal clutch 51 is fitted to the driven shaft 50 through the spline 148 at a position facing the inner rotating member 51A so as not to be relatively rotatable. The outer periphery of the outer rotating member 51B covers the inner rotating member 51A. When the driven pulley reaches a predetermined number of rotations, the rotation is transmitted through the inner rotating member 51A and the outer rotating member 51B, and the driven shaft 50 starts rotating. As described with reference to FIG. 2, the rotation of the driven shaft 50 is decelerated via the gear of the gear reducer 46, transmitted to the rear wheel shaft 60, and the rear wheel 5 is driven.

  The matters described in the claims correspond to the part relating to the axial drive mechanism of the drive pulley movable half 49 in the above embodiment, which has been described in relation to FIGS. The “screw type feed mechanism” described in the claims is the screw type feed mechanism 89 shown in FIG. 3, the “axially fixed side screw part” is the female threaded cylindrical member 76, and “the axially fixed side screw assembly”. "Indicates a female screw assembly 79," axially movable side threaded portion "refers to a male threaded cylindrical member 80, and" axially movable side threaded assembly "refers to a male threaded assembly 83.

The V belt type continuously variable transmission of the above embodiment provides the following effects.
(1) The input gear (annular gear 77) of the screw-type feed mechanism that is engaged with and driven by the final gear of the reduction gear mechanism (the small gear 102 of the second intermediate gear) is an axially fixed screw assembly (female screw). Since it is a gear of the assembly 79) and does not move in the axial direction, the width of the final stage gear (the small-diameter gear 102 of the second intermediate gear) of the reduction gear mechanism can be reduced, and the speed change mechanism can be downsized. Can do.
(2) Since the axially movable side screw portion (male screw cylindrical member 80) and the bearing member (ball bearing 72) are arranged using the inside of the width of the axially fixed side screw portion (female screw cylindrical member 76), The dead space can be effectively used to reduce the size of the transmission.
(3) Between the input gear (annular gear 77) of the axially fixed side screw assembly (female screw assembly 79) and the umbrella-like portion of the pulley movable half (the umbrella-like portion 49A of the drive pulley movable half). Since one of the reduction gears (the large diameter gear 101 of the second intermediate gear) is arranged using the dead space effectively, the transmission can be reduced in size.

It is a side view of the power unit 1 which concerns on this invention. FIG. 2 is a developed cross-sectional view of the AA cross section, the BB cross section, and the CC cross section of FIG. 4 is an enlarged cross-sectional view showing a state in which the drive pulley 47 and its peripheral members are assembled to the crankshaft 11. FIG. It is an expanded sectional view of only the shaft part of the IV-IV section of FIG. FIG. 3 is a cross-sectional development view of the front half of the transmission 3. FIG. 3 is an arrangement diagram of gears and the like when the front half of the transmission is viewed from the side. 3 is a developed sectional view of the rear half of the transmission 3. FIG. FIG. 6 is an arrangement diagram of gears and the like when the rear half of the transmission is viewed from the side.

Explanation of symbols

11 ... Crankshaft, 38 ... Transmission case, 45 ... V belt type continuously variable transmission, 47 ... Drive pulley, 48 ... Drive pulley fixed half, 49 ... Drive pulley movable half, 49A ... Umbrella-shaped part, 49B ... Cylindrical part, 72 ... Ball bearing, 76 ... Female screw cylindrical member, 77 ... Ring gear, 79 ... Female screw assembly, 80 ... Male screw cylindrical member, 81 ... Non-rotating member, 83 ... Male screw assembly, 88 ... Non-rotating mechanism, 89: screw feed mechanism, 91: electric motor, 101: large diameter gear, 102: small diameter gear, 104: second intermediate gear.

Claims (3)

A pulley fixing half (48) fixedly supported on the rotating shaft (11);
The rotary shaft (11) faces the pulley fixing half (48) and is supported so as to be movable in the axial direction in a state in which the rotation with respect to the rotary shaft (11) is prevented, and cooperates with the pulley fixing half (48). In the V-belt type continuously variable transmission having a pulley movable half (49) that sandwiches the belt (55),
Comprising axially stationary threaded portion (76), with the axial movement are integrally held in the axial direction relative immovably mounted ball bearing (63) is blocked with respect to the axis of rotation (11) rotating shaft (11) to be rotatable relative to the holding, the axial fixed-side screw assembly which is driven to rotate via the reduction gear mechanism (92) from the electric motor (91) (79),
It has an axially movable side threaded part (80) that fits into the axially fixed side threaded part (76), and is held so as to be movable in the rotational axis direction while preventing rotation with respect to the transmission case (38). A screw type feed mechanism (89) consisting of an axially movable side screw assembly (83)
An axially movable screw assembly (83) of the screw type feed mechanism (89) is attached to the pulley movable half (49) so as not to be axially movable and relatively rotatable. Step transmission. Axially movable threaded portion (80), is supported relatively rotatable and axially moved relative non ability via a bearing member (72) on the cylindrical shaft portion of the pulley movable-half (49) (49B) In addition, the axially movable side screw portion (80) and the bearing member (72) are arranged on the inner side of the axially fixed side screw portion (76) on the cylindrical shaft portion (49B) of the pulley movable half (49). The V-belt type continuously variable transmission according to claim 1, wherein the V-belt continuously variable transmission is provided.   One of the reduction gears in the gap between the input gear (77) of the axially fixed screw assembly (79) and the umbrella-shaped part (49A) of the pulley movable half (49) in the screw-type feed mechanism (89) The V-belt type continuously variable transmission according to claim 1, wherein (101) is arranged.

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