WO2023084592A1

WO2023084592A1 - Belt-type continuously variable transmission

Info

Publication number: WO2023084592A1
Application number: PCT/JP2021/041166
Authority: WO
Inventors: 裕康吉澤; 康平松浦; 靖司藤本; 剛狩野; 進介川窪; 直輝沖本; 功祐綱島
Original assignee: 本田技研工業株式会社
Priority date: 2021-11-09
Filing date: 2021-11-09
Publication date: 2023-05-19

Abstract

The present disclosure is directed to a configuration that enables degree of freedom in designing a belt-type continuously variable transmission to be increased. A belt-type continuously variable transmission 10 according to an embodiment is a belt-type continuously variable transmission in which a belt runs over a driving pulley to which driving force from an output shaft of a motive power source is transmitted, and a driven pulley. In the belt-type continuously variable transmission, a driving mechanism includes a motor that generates driving force in an axial direction of a movable pulley half in the driving pulley, so as to move the movable pulley half with respect to a fixed pulley half. The driving mechanism is rotated by rotation of the motor, and includes a screw member that extends in the axial direction and is immovable in the axial direction, and a movable holder that has a female screw portion to which the screw member is screwed and that is movable in the axial direction along with the movable pulley half. The screw member 134 is situated on the output shaft 20 side with respect to a peripheral portion 64o of the movable pulley half 64b.

Description

belt type continuously variable transmission

TECHNICAL FIELD The present invention relates to a belt-type continuously variable transmission including a driving pulley to which driving force is transmitted, a driven pulley, and a belt stretched between them. Regarding a stepped transmission.

Conventionally, a belt-type continuously variable transmission is used between the internal combustion engine, which is the power source, and the drive wheels in straddle-type vehicles. A belt-type continuously variable transmission includes a drive pulley that transmits driving force, a driven pulley that transmits power to the drive wheels, a V-belt that is stretched between them, and a mechanism that changes the groove width of these pulleys. I have.

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 be relatively rotatable and axially immovable. An electric motor is mounted so that its rotor shaft is parallel to the input shaft to which the drive pulley is mounted, and a shift control mechanism is provided for axially operating the shift member 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 into which the male thread portion of the screw shaft is screwed. It is supported by the case via bearings. The internally threaded member is integrally connected to the distal end of the arm of the shift member. Therefore, when the electric motor operates and the screw shaft rotates forward, the female screw member is sent to move the shift member in the top direction, bringing the movable pulley half closer to the fixed pulley half side of the drive pulley. Conversely, when the screw axis is reversed, the internally threaded member is forced to move the shift member in the row direction, moving the movable pulley half away from the fixed pulley half.

Japanese Patent Application Laid-Open No. 2013-029130

In order to increase the degree of freedom in design, for example, a configuration that enables further miniaturization is desirable. SUMMARY OF THE INVENTION It is an object of the present invention to provide a configuration that enables an increased degree of design freedom in a belt-type continuously variable transmission.

One aspect of the present invention is
A belt is stretched between a driving pulley to which a driving force is transmitted from an output shaft of a power source and a driven pulley, and the movable pulley moves the movable pulley half relative to the fixed pulley half in the driving pulley. A belt-type continuously variable transmission in which a drive mechanism for generating driving force in the axial direction of the halves is provided with a motor,
The drive mechanism is
a screw member that is rotated by rotation by the motor, extends in the axial direction, and is immovable in the axial direction;
a movable holder having a female threaded portion with which the screw member is screwed and movable in the axial direction together with the movable pulley half;
The belt-type continuously variable transmission is characterized in that the screw member is positioned closer to the output shaft than the outer peripheral portion of the movable pulley half.

According to the above configuration, the movable holder can be directly driven by the screw member, and this driving position can be brought closer to the load position on the belt on the driving pulley in the radial direction about the output shaft. Therefore, it is possible to suppress the inclination of the movable pulley half, and to reduce the size of the drive mechanism in the radial direction, thereby making it possible to reduce the size of the belt-type continuously variable transmission. Therefore, it is possible to increase the degree of freedom in designing the belt-type continuously variable transmission.

Preferably, the drive mechanism is provided in a case that accommodates the motor and is provided with a speed reduction mechanism to which driving force is transmitted by the motor, and the screw member is a case wall portion that extends in a radial direction of the case. A first bearing and a second bearing are provided around the screw member so as to sandwich the case wall portion, and the first bearing receives a radial load and an axial load. and the second bearing is configured to be able to receive an axial load. With this configuration, the radial load and the axial load generated in the screw member can be firmly received, so that the belt-type continuously variable transmission can be made smaller or lighter by thinning the case or the like.

Preferably, the screw member has a radially extending flange portion, and the first bearing and the second bearing are arranged between the flange portion closer to the movable pulley half than the case wall portion and the case wall portion. It is sandwiched between the flange portion and a fastening member located on the opposite side and screwed to the screw member. With this configuration, the pull-out toughness of the screw member can be improved.

Preferably, the drive mechanism is provided in a case that accommodates the motor and is provided with a speed reduction mechanism to which driving force is transmitted by the motor, and the outer peripheral surface of the movable holder serves as a seal surface between the case and the case. and a cap member is provided on the movable pulley half side of the female threaded portion. With this configuration, compared to the case where the sealing member is provided at the axial end of the output shaft, the amount of axial extension of the belt-type continuously variable transmission can be shortened, and the amount of protrusion of the entire unit of the drive mechanism can be reduced. be able to.

Preferably, a hole communicating between the inside and outside of the case is formed in the upper portion of the case in the vertical direction. As a result, it is possible to take air into the case while suitably preventing entry of water or the like into the case.

Preferably, the hole is provided at a position further from the movable pulley half than the movable holder in the axial direction. As a result, the hole can be separated from the front side of the case, and dust and water can be prevented from entering the case through the hole.

Preferably, an extension tube portion is provided so as to extend the hole to the outside of the case, and a cover portion is further provided so as to partially cover an outer inlet of the extension tube portion. With this configuration, it is possible to form a labyrinth-like flow path around the cover part that partially covers the outer inlet of the extension tube part, so that water, oil, and the like can flow positively from the outer inlet of the extension tube part. Intrusion of fluid can be prevented.

Preferably, a drain hole is formed in the vertically lower portion of the case, and a drain member is provided in the drain hole. With this configuration, even if water enters the case, it is possible to ensure the drainage of the case.

Preferably, the belt-type continuously variable transmission converts rotational motion of the output shaft into axial motion of the output shaft so as to assist the axial movement of the movable pulley half by the drive mechanism. It also has a converting cam assist mechanism. Thereby, the axial movement of the movable pulley half by the drive mechanism can be favorably assisted.

Preferably, the cam assist mechanism is of a ball cam type, and includes an inner member provided so as to be rotatable integrally with the output shaft, and the movable pulley half along the outer peripheral surface of the inner member. An axially movable outer member and at least one ball member associated with the inner member and the outer member are provided. With this configuration, the rotational motion of the output shaft can be suitably converted into the axial motion of the output shaft.

According to the aspect of the present invention, since it has the above configuration, it is possible to further increase the degree of freedom in designing the belt-type continuously variable transmission.

FIG. 1 is a schematic left side view of a motorcycle equipped with a power unit having a belt-type continuously variable transmission according to an embodiment of the present invention. 2 is a front view of the power unit of FIG. 1. FIG. 3 is a cross-sectional developed view of the power unit taken along line III-III in FIG. 1. FIG. 4 is an enlarged view of the drive pulley and its drive system portion of FIG. 3. FIG. FIG. 5 is an enlarged view of the drive pulley and its drive system portion of FIG. 3, and is a view when the movable drive pulley halves are moved as indicated by broken lines in FIG. 6 is a front view of a movable holder in the belt-type continuously variable transmission of FIG. 1. FIG. 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. 8 is a perspective view showing a ball member disposed on an inner boss of the cam assist mechanism in the belt-type continuously variable transmission of FIG. 1. FIG. 9 is a perspective view showing a portion of the outer boss around the ball-located inner boss of FIG. 8. FIG. 10 is a cross-sectional view taken along line XX of FIG. 9. FIG. 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. 12 is a cross-sectional view at the position of one ball member in the cam assist mechanism in the belt-type continuously variable transmission of FIG. 1. FIG. FIG. 13 is a diagram showing a simplified relationship between a groove and an axis in the inner boss of the cam assist mechanism in the belt-type continuously variable transmission of FIG. FIG. 14 is a perspective view from diagonally forward of a case housing a drive mechanism in the belt-type continuously variable transmission of FIG. 1 and a portion of the surroundings thereof. FIG. 15 is a perspective view of a case in which the drive mechanism is accommodated in the belt-type continuously variable transmission of FIG. FIG. 16 is a view showing the arrangement of gears of the drive mechanism in the belt-type continuously variable transmission of FIG. 1, and is a view of the left side of the case housing the drive mechanism as seen from the axial direction. 17 is a cross-sectional view along line XVII-XVII of FIG. 16. FIG. FIG. 18 is a cross-sectional view around a drive pulley of a belt-type continuously variable transmission of a modification. FIG. 19 is a diagram showing the gear arrangement of the drive mechanism in the belt-type continuously variable transmission of FIG. 18, and is a view of the left side of the case housing the drive mechanism as seen from the axial direction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A belt-type continuously variable transmission 10 according to one embodiment will be described with reference to FIGS. 1 to 16. FIG. It should be noted that directions such as front, rear, left, right, up and down in the description and claims of this specification follow the directions of the straddle-type vehicle equipped with the power unit P equipped with the belt-type continuously variable transmission 10 according to the present embodiment. . In the present embodiment, the straddle-type vehicle is specifically a scooter-type motorcycle (hereinafter simply referred to as “motorcycle”) 1 . Further, an arrow FR in the drawing indicates the front of the straddle-type vehicle according to the present embodiment, LH indicates the left side of the vehicle, RH indicates the right side of the vehicle, and UP indicates the upper side of the vehicle.

FIG. 1 shows an overview of the left side of a motorcycle 1 equipped with a power unit P employing a belt-type continuously variable transmission 10 according to this embodiment. FIG. 2 is an enlarged view of the power unit P of FIG. FIG. 3 is a cross-sectional developed view of the power unit P taken along line III-III in FIG. 4 and 5 are respectively enlarged views of a part of the belt-type continuously variable transmission 10 of FIG.

In the motorcycle 1 of this embodiment, the front part 1f of the vehicle body and the rear part 1r of the vehicle body are connected via the low floor part 1c. Consists of That is, a down tube 3 extends downward from a head pipe 2 in the front portion 1f of the vehicle body, the down tube 4 bends horizontally at its lower end and extends rearward under the floor portion 1c, and a pair of left and right main pipes 4 are formed at its rear end. The main pipe 4 rises upward from the connecting portion, bends, and extends obliquely rearward.

A seat 5 is arranged above the main pipe 4. On the other hand, in the front portion 1f of the vehicle body, a handlebar 6 is provided upwardly while being pivotally supported by the head pipe 2, and a front fork 7 extends downward, and a front wheel Wf is pivotally supported at the lower end thereof. A power unit P is mounted on the motorcycle 1 while being supported by a main pipe 4 .

At the bottom of the power unit P, a main stand 8 is provided that can be raised and lowered. The main stand 8 has an operating arm 8b extending leftward from a leg portion 8a, and has a footrest plate 8c at its tip.

The power unit P has an internal combustion engine E at the front, and a power transmission transmission section T integrally extending from the internal combustion engine E rearward on the left side of the rear wheel Wr. As shown in FIG. 3, the power transmission transmission portion T includes a transmission case 12 integrally extending rearward from the internal combustion engine E, and a transmission case 12 covering the transmission case 12 from the outside in the vehicle width direction and forming a belt chamber 14. A machine case cover 16 is provided, and a belt type continuously variable transmission 10 is accommodated in a belt chamber 14.例文帳に追加An outer cover 18 is provided on the left outer side of the transmission case cover 16 (see FIGS. 1 and 2).

The internal combustion engine E, which is a power source, is a single-cylinder four-stroke internal combustion engine, and a cylinder block 24, a cylinder head 26, and a cylinder head cover 28 extend forward from a crankcase 22 supporting a crankshaft 20 oriented in the vehicle width direction. It protrudes and leans forward to a state that is almost horizontal.

A pair of left and right support brackets extend downward from the lower end of the crankcase 22. The support brackets are connected to a bracket 32 projecting rearward from the front lower portion of the main pipe 4 via a link member 34, thereby A power unit P is swingably connected and supported with respect to.

The power transmission transmission section T, which extends rearward from the internal combustion engine E in the power unit P, has a rear axle 36, which is an output shaft of a reduction gear mechanism Tr, provided at its rear portion, and rear wheels Wr, which are driving wheels, are provided. ing.

A rear cushion 9 is interposed between the support bracket 38 erected at the rear end of the power transmission transmission portion T and the rear portion of the main pipe 4 .

An intake pipe 40 extends from the upper portion of the cylinder head 26 of the internal combustion engine E, which tilts forward greatly, curves backward, and reaches an air cleaner 44 above the belt-type continuously variable transmission 10 via a throttle body 42. On the other hand, an exhaust pipe 46 extending downward from the lower portion of the cylinder head 26 is bent rearward, extends rearward while biased to the right, and is connected to a muffler 48 on the right side of the rear wheel Wr.

As shown in FIG. 3, which is a cross-sectional developed view of the power unit P taken along line III-III in FIG. The front part 12a of the transmission case 12, which extends long in the front-rear direction on the left side, is combined with the left-right front part 12a.

The transmission case 12 has a rear portion 12b that extends rearward from the front portion 12a to the left side of the rear wheel Wr, and forms an elongated oval bowl shape that opens to the left. A transmission case cover 16 is placed on the open surface on the left side of the transmission case 12 to form a belt chamber 14 therein. A right open surface of the rear portion 12b of the transmission case 12 is covered with a reduction gear cover 50, and a reduction gear chamber 52 is formed therein in which the reduction gear mechanism Tr is accommodated. A power transmission section T is formed including a reduction gear mechanism Tr provided in the rear portion 12b.

Inside the so-called crankcase 22 formed by combining the right crankcase 22r and the front portion 12a of the transmission case 12, the crankshaft 20 rolls left and right on the side walls of the right crankcase 22r and the front portion 12a of the transmission case 12. It is rotatably supported via

main bearings

54 and 55 which are bearings.

In the internal combustion engine E, a connecting rod 58 connects the piston 56 that reciprocates in the cylinder liner 24a of the cylinder block 24 and the crankpin 21 of the crankshaft 20.

A cam chain drive sprocket 60 is rotatably fitted to the right outer shaft portion of the outer shaft portion extending in the left-right horizontal direction of the crankshaft 20, and an AC generator 62 is provided at the right end thereof. A driving pulley 64 of the belt-type continuously variable transmission 10 is provided on the shaft. That is, 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 .

The 4-cycle internal combustion engine E of this embodiment employs a SOHC type valve system, and a valve train 66 is provided in the cylinder head cover 28. It is constructed between the shaft 70 and the crankshaft 20, and a cam chain chamber 72 therefor is provided so as to communicate with the right crankcase 22r, the cylinder block 24, and the cylinder head . That is, a cam chain 68 is positioned in a cam chain chamber 72 between a cam chain driven sprocket 74 fitted to the right end of a camshaft 70 oriented in the left-right horizontal direction and a cam chain driving sprocket 60 fitted to the crankshaft 20. is bridged through

A 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 faces a fixed drive pulley half 64a fitted near the left end of the crankshaft 20 on the right side thereof. and an axially slidable movable drive pulley half 64b. The fixed pulley half in drive pulley 64 is fixed drive pulley half 64a and the movable pulley half is 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.

Movable drive pulley half 64b is moved axially in conjunction with variable speed drive mechanism D and cam assist mechanism C, thereby moving toward and away from fixed drive pulley half 64a. can. The transmission drive mechanism D and the cam assist mechanism C will be described in detail later, but the cam assist mechanism C will be briefly described here first.

The cam assist mechanism C is of the ball cam type, and includes an inner boss 80, an outer boss 88, and a ball member 150 provided so as to engage therewith.

As shown in FIGS. 3 to 5, particularly FIGS. 4 and 5 thereof, the left extension from the left small diameter step 76 of the main bearing 55 on the left side of the crankshaft 20 has a sleeve from the right. 78, cylindrical inner boss 80, sleeve 82, fixed drive pulley half 64a are fitted in this order. A sleeve 78, an inner boss 80, a sleeve 82, and a fixed drive pulley half body 64a are fastened to the crankshaft 20 by fastening them to the left end surface of the crankshaft 20 with a nut 86 via a washer 84. unite. Accordingly, the fixed drive pulley half 64a and the inner boss 80 are each fixed integrally with the crankshaft 20 and rotate integrally therewith. At least one of the sleeve 78 and the sleeve 82 may be formed integrally with the inner boss 80 .

On the other hand, the movable drive pulley half 64b, which faces the fixed drive pulley half 64a on the right side, is provided integrally with the cylindrical outer boss 88 that serves as its base. The outer boss 88 is arranged such that its inner peripheral surface 88i slidably contacts the outer peripheral surfaces of the sleeve 78 and the sleeve 82 and is axially movable with respect 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 80 a of the inner boss 80 . As will be 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, that is, the axis 20A of the crankshaft 20. Relative rotation in range and axial movement with that rotation are possible. 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 rotational motion of the crankshaft 20 into axial motion of the crankshaft 20 . Therefore, when the movable drive pulley half 64b approaches or separates from the fixed drive pulley half 64a due to the axial driving force exerted by the speed change drive mechanism D, which will be described later, the movable drive pulley half 64b is integrally provided. Outer boss 88 substantially rotates about crankshaft 20 while simultaneously moving axially.

Thus, the right movable drive pulley half 64b facing the left fixed drive pulley half 64a rotates about the crankshaft 20 and moves axially toward or away from the fixed drive pulley half 64a. be able to. A V-belt 90 is sandwiched and wound between the tapered surfaces facing each of the drive pulley halves 64a and 64b.

Behind the driving pulley 64, a driven pulley 94 rotatably supported by a driven shaft 92, which is the input shaft of the reduction gear mechanism Tr, faces a fixed driven pulley half 94a on the left side and slides in the axial direction. and a moveable driven pulley half 94b.

An inner sleeve 96 is rotatably supported on the driven shaft 92 via a bearing while its movement in the axial direction is restricted. Welded and attached together.

An outer sleeve 98 is fitted around 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 an elongated hole formed in the outer sleeve 98 in the axial direction. Together, the outer sleeve 98 can move relative to the inner sleeve 96 in the axial direction, but the relative rotation is restricted.

A movable driven pulley half 94b is integrally fixed to the right end flange of the outer sleeve 98 by welding the center hole thereof. Thus, movable driven pulley half 94b rotates with fixed driven pulley half 94a, but can move axially toward and away from fixed driven pulley half 94a.

A clutch inner 102 of a centrifugal clutch 100 is fixed to the left end of the inner sleeve 96 with a nut. Pulley half 94b is biased to the right.

In the belt-type continuously variable transmission 10, a V-belt 90, which is a belt, 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 according to the engine speed, thereby moving the movable drive pulley half 64b with respect to the fixed drive pulley half 64a, thereby forming a V-belt on the drive pulley 64. The winding diameter of 90 changes, and the winding diameter of the driven pulley 94 changes accordingly, whereby the gear ratio is automatically changed and the gear ratio is continuously changed.

The centrifugal clutch 100 has a bowl-shaped clutch outer 104 that covers the outer periphery of the clutch inner 102 and is provided near the left end of the driven shaft 92 with its base fixed by a nut 106. The clutch inner 102 is biased by a spring 108. A clutch shoe 112 rotatably supported by a support shaft 110 is provided facing the inner peripheral surface of the clutch outer 104 .

Since the clutch inner 102 of the centrifugal clutch 100 rotates together with the continuously variable driven pulley 94 of the belt-type continuously variable transmission 10, the clutch shoe 112 of the clutch inner 102 is rotated by centrifugal force when the rotation speed exceeds a predetermined speed. It swings against the spring 108 and comes into contact with the inner peripheral surface of the clutch outer 104 , rotates the clutch outer 104 integrally, and transmits power to the driven shaft 92 .

The driven shaft 92 is supported by the transmission case 12 and the transmission case cover 16 via

bearings

113 and 114, and the right end inserted into the reduction gear chamber 52 on the rear right side of the transmission case 12 is connected to the reduction gear cover 116. is supported via bearings 117.

In the reduction gear mechanism Tr in the reduction gear chamber 52, the reduction intermediate shaft 118 is installed between the driven shaft 92 and the rear axle 36 in parallel (horizontal direction) to the transmission case 12 and the reduction gear cover 116. A reduction gear mechanism Tr is configured by the gears on each shaft. 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 to rotate the rear wheel Wr.

When the belt-type continuously variable transmission 10 is operating with the operation of the internal combustion engine E, the cooling fan 64f integrally formed on the left side of the fixed drive pulley half 64a also rotates together with the fixed drive pulley half 64a. As a result, the outside air taken in from the outside air intake port 18a (see FIGS. 1 and 2) provided in the outer cover 18 toward the side of the vehicle passes through the cooling air intake port of the transmission case cover 16 and enters the transmission case. It is introduced into the belt chamber 14 inside the cover 16 . The flow of cooling air in the belt chamber 14 is schematically indicated by arrows in FIG.

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 movable drive pulley half 64b is axially moved with respect to the fixed drive pulley half 64a by the operation of the speed change drive mechanism D corresponding to the engine speed. The winding diameter of the V-belt 90 changes, and simultaneously the winding diameter of the driven pulley 94 changes, whereby the gear ratio is automatically changed and the speed is continuously changed. Here, the transmission drive mechanism D will be described in detail mainly based on FIGS. 3 to 6. FIG. The variable speed drive mechanism D corresponds to the drive mechanism in the present invention, and includes a motor, that is, a variable speed drive motor 120 . The variable speed drive mechanism D is configured to generate an axial drive force in the drive pulley 64 relative to the fixed drive pulley half 64a to move the movable drive pulley half 64b in the axial direction. It is The axial direction of the movable drive pulley half 64b is the axial direction of the drive pulley 64 and coincides with the axial direction of the crankshaft 20. As shown in FIG.

The transmission drive mechanism D is positioned on the front left side of the front portion 12 a of the transmission case 12 . The cam assist mechanism C and the speed change drive mechanism D are provided in the unit case 122 . Motor 120 of transmission drive mechanism D is housed in unit case 122, and deceleration mechanism 124 of transmission drive mechanism D is attached to unit case 122. As shown in FIG. The unit case 122 is split left and right, and is composed of a right case 122a facing the front portion 12a of the transmission case 12 on the left side, and a left case 122b fixed to the right case 122a by bolts 123. A motor 120, a speed reduction mechanism 124, and an axial feed mechanism M are arranged in this order from the outside in the radial direction with 20 as the center. A cam assist mechanism C is arranged inside the axial feed mechanism M in the radial direction.

The unit case 122 is shaped so that the left extending portion is inserted from the stepped portion 76 of the main bearing 55 on the left side of the crankshaft 20, the diameter of which changes to a small diameter on the left side. A through hole (hereinafter referred to as a shaft through hole) 122i through which the crankshaft 20 is inserted is formed, and a through hole (hereinafter referred to as a shaft through hole) 122h through which the crankshaft 20 is inserted is also formed in the left case 122b.

The motor 120 is positioned on the front FR side of the vehicle in the transmission drive mechanism D. Motor 120 is arranged in left case 122b so that drive shaft 120a of motor 120 is parallel to crankshaft 20, and drive gear 120b is formed on drive shaft 120a of motor 120. As shown in FIG. Both ends of the first reduction gear shaft 130s are supported via

bearings

126 and 128 in bearing

recesses

122c and 122d facing each other inside the unit case 122. Gear 130a meshes with drive gear 120b of drive shaft 120a of motor 120 . The first reduction gear shaft 130s is provided parallel to the driving shaft 120a of the motor 120. As shown in FIG. 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 axially aligned with the large-diameter gear 130a. The first reduction gear 130 in the reduction mechanism 124 includes a first reduction gear shaft 130s, a large diameter gear 130a and a small diameter gear 130b.

The reduction mechanism 124 includes a second reduction gear 132 in addition to the first reduction gear 130 . The second reduction gear 132 has a large diameter gear 132a that meshes with the small diameter gear 130b of the first reduction gear shaft 130s. The large gear 132a includes a tubular portion 132b extending from the large gear 132a to one side, ie, to the right in FIGS. 3-5, along the central axis of the large gear 132a. A gear shaft portion 134a on the right end side of the screw member 134 is press-fitted into the tubular portion 132b along the axis of the second reduction gear 132, that is, the large-diameter gear 132a. Therefore, the large-diameter gear 132a is fixed to the screw member 134 integrally.

The tubular portion 132b into which the gear shaft portion 134a is press-fitted so as to pass through the center thereof is arranged in a state of being inserted into the through hole 122e in the axial direction of the right case 122a of the unit case 122. At this time, two

bearings

136 and 138 are provided on the outer circumference of the tubular portion 132b of the second reduction gear 132 so that the two

bearings

136 and 138 sandwich the right case 122a. In addition, in the right case 122a, the through hole 122e is positioned radially outside the shaft through hole 122i.

A bearing 136, which is a rolling bearing, is provided between the tip of the cylindrical portion 132b of the second reduction gear 132, that is, the outer end of the right case 122a and the stepped portion 122f near the through hole 122e of the right case 122a. Bearing 136 is configured to be able to receive a radial load. More specifically, the bearing 136 is constructed so as to be able to receive not only a radial load but also an axial load. A collar 133, which is a cylindrical member, is provided at the tip of the tubular portion 132b of the second reduction gear 132 so as to be continuous therewith. A bearing 136 is provided radially outside of 132b and collar 133. As shown in FIG. Then, as shown in FIGS. 3 to 5, a nut 140 is screwed onto the male screw portion 134b at the tip of the gear shaft portion 134a of the screw member 134 and tightened so that the bearing 136 defines the through hole 122e of the right case 122a. It is fixed between the hole wall portion 122g and the nut 140. On the other hand, 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, the left end near the large-diameter gear 132a. 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 in the axial direction between the large-diameter gear 132a and the hole wall portion 122g defining the through hole 122e of the right case 122a so as to be in contact with them. The second reduction gear 132 having the

bearings

136 and 138 thus provided has a gear shaft 134a press-fitted thereon, and a nut 140 is screwed onto the male threaded portion 134b at the tip of the gear shaft 134a. By tightening the nut 140, the right case 122a is It is attached to the right case 122a so as to be rotatable with respect to but axially immovable.

The screw member 134, which is rotatable with respect to the right case 122a but is attached to the right case 122a so as not to move in the axial direction, includes, in order from the right side in FIGS. It has a portion 134a, a flange portion 134c and an externally threaded portion 134d, which are aligned in the axial direction of the screw member 134. The second reduction gear 132, that is, the large-diameter gear 132a, hits and contacts the flange portion 134c on the left side thereof. Therefore, the screw member 134 is held by the

bearings

136, 138 with the right side case 122a sandwiched between the

bearings

136, 138. Therefore, for example, when a force acts on the screw member 134 and a radial load is generated, or when a force is applied to the screw member 134, When an axial load occurs, the load can be received by bearing 136, and when a force acts on screw member 134 and an axial load occurs in the right direction, the load can be received by bearing 138. Furthermore, since the screw member 134 uses the nut 140 and the flange portion 134c to prevent the

bearings

136 and 138 from coming off, the allowable axial load, that is, the allowable thrust load, can be improved, and the screw member 134 can be prevented from coming off. can be enhanced.

The variable speed drive mechanism D is further equipped with a movable holder 142 that is axially movable. FIG. 6 shows a plan view of the movable holder 142 viewed from the left side in FIGS. 3 to 5. As shown in FIG. The movable holder 142 is donut-shaped and has a through hole 142a extending in the axial direction at the center thereof. The crankshaft 20 and the cam assist mechanism C provided therearound are arranged in the through hole 142a. A bearing 144, which is a rolling bearing, is held by a bearing holding portion 88c, which is a holding portion on the outer peripheral side of the outer boss 88 of the cam assist mechanism C, and a holding portion 142b provided on a wall portion that defines the through hole 142a of the movable holder 142. , the bearing 144 supports the movable holder 142 so as to be relatively rotatable with respect to the crankshaft 20 . The movable holder 142 is arranged in the shaft through hole 122h of the left side case 122b of the unit case 122, and a sealing member is provided between the outer peripheral surface 142c of the movable holder 142 and the shaft through hole 122h of the left side case 122b of the unit case 122. An X-ring 146 is sandwiched and sealed. An O-ring, an oil seal, or the like may be used as the sealing member.

A male threaded portion 134d on the left side of the flange portion 134c of the screw member 134 is screwed into a female threaded hole 142d of the movable holder 142, which is a female threaded portion. The screw member 134 constitutes an axial feed mechanism (axial feed mechanism) M together with the movable holder 142 . Since the male threaded portion 134d is a trapezoidal thread, it is suitable for motion transmission. In the movable holder 142, the female screw hole 142d is provided radially outside the through hole 142a and radially inside the outer peripheral surface 142c thereof. The male threaded portion 134d of the screw member 134 enters and is screwed into the female threaded hole 142d from the right side. A cap member 148 seals the left end of the female screw hole 142d.

Therefore, in the speed change drive mechanism D, when the speed change drive motor 120 drives 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 changes to the small-diameter gear 130a. It rotates at a reduced speed together with the gear 130b, and the large-diameter gear 132a meshing with the small-diameter gear 130b rotates. The engagement between the portion 134d and the female threaded hole 142d of the movable holder 142 is displaced in the axial direction, thereby moving the movable holder 142 in the axial direction. As the movable holder 142 is moved in the axial direction by forward and reverse driving of the speed change driving motor 120, the outer boss 88 of the cam assist mechanism C is moved with respect to the inner boss 80. As indicated by the dashed lines and shown in FIGS. 4 and 5, the movable drive pulley half 64b can be moved toward or away from the fixed drive pulley half 64a so that both drive pulley halves 64a, 64b face each other. The winding diameter of the V-belt 90 wound between the tapered surfaces is changed to perform stepless speed change.

The speed reduction mechanism 124 has an arrangement structure 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 reduced, and as a result, the amount of radial projection of the speed reduction mechanism 124 from the crankshaft 20 can be reduced.

Here, the aforementioned cam assist mechanism C will be further explained. As described above, the cam assist mechanism C is of the ball cam type, and includes the inner boss 80, the outer boss 88, and the ball members 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 in this order from the right to the left extension from the stepped portion 76 of the crankshaft 20. As shown in FIG. The inner boss 80 is integral with the crankshaft 20 , rotates with the crankshaft 20 and is axially immovable relative to the crankshaft 20 . On the other hand, the outer boss 88 is arranged 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 is attached to the inner boss 80. When the outer boss 88 slides against it, it rotates substantially about the crankshaft 20 with the outer boss 88 and moves axially. A ball member 150 is provided to provide axial movement due to 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, and the movable drive pulley half 64b. and a ball member 150 for effecting rotation and axial movement of the outer boss 88 relative to the inner boss 80 . Although the number of ball members 150 is four here, it can be at least one.

A perspective view of the inner boss 80 is shown in FIG. FIG. 7 is a view of the inner boss 80 viewed from the internal combustion engine E side in FIG. 7, the directional arrows RH and LH in FIG. 3 are also attached. The inner boss 80 is cylindrical, and the rolling surface 80f of the ball member 150 is formed on the outer peripheral surface 80a. Here, since four ball members 150 are used, the same number of grooves 80b as the number of ball members 150 are formed on the outer peripheral surface 80a of the inner boss 80, which will be four rolling surfaces 80f. Each groove 80b has an arc-shaped cross section and extends spirally around the axis of the inner boss 80. As shown in FIG. This rolling surface 80f, that is, the helical shape of the groove portion 80b, in the arrangement of the inner boss 80 shown in FIGS. is determined to be twisted in the direction opposite to the 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.

FIG. 8 shows the arrangement of the ball members 150 corresponding to the respective grooves 80b. A ball member 150 arranged so as to be able to travel in the groove portion 80b of the inner boss 80 is provided in the hole portion 88a of the outer boss 88. As shown in FIG. FIG. 9 shows a state in which an outer boss 88 is arranged outside the inner boss 80 of FIG. It is shown in FIG. A perspective view of the outer boss 88 is shown in FIG. 11, with directional arrows RH and LH in FIG. However, in FIGS. 9 and 10, only a part of the outer boss 88 is cut out and shown. 3 to 5, when the crankshaft 20 is provided with the cam assist mechanism C, the axis 20A of the crankshaft 20 coincides with the axis of the inner boss 80 and the axis of the outer boss 88. 7-11, the axis 20A of crankshaft 20 is shown as the axis of inner boss 80 or outer boss 88. FIG.

The outer boss 88 has a cylindrical shape 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 distal end portion 88b has the smallest diameter, and the intermediate portion 88m and the pulley mounting portion 88d have larger diameters in this order. The bearing holding portion 88c has a stepped portion 88e for holding the bearing, and an annular groove portion 88f in which a stopper for holding the bearing is fitted on the right side of the stepped portion 88e. The movable drive pulley half 64b is fixed to the pulley mounting portion 88d so as to sandwich the flange portion 88g of the pulley mounting portion 88d (see FIGS. 4 and 5). Although the movable drive pulley half 64b is attached to the pulley attachment portion 88d by casting, it may be attached by various joining means such as welding or mechanical joining means.

The outer boss 88 is provided with four holes 88a extending in the radial direction. The four hole portions 88a are through holes, respectively, and are provided in the bearing holding portion 88c of the outer boss 88. As shown in FIG. The four holes 88a are formed at the same position in the axial direction and arranged at intervals of 90° in the circumferential direction. The outer peripheral ends of the four holes 88a are closed by inner races 144a of the aforementioned bearings 144 provided between the drive mechanism D and the cam assist mechanism C. As shown in FIG. That is, the hole portion 88a is closed by the inner race 144a of the bearing 144, and is closed 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. Note that the bearing 144 comprises an inner race 144a, an outer race 144b and a plurality of balls 144c therebetween.

A disc spring 152, which is an elastic member, is arranged between the inner race 144a of the bearing 144 and the ball member 150 in the hole 88a, as shown in FIGS. The disc spring presses the ball member 150 toward the inner boss 80, thereby allowing the ball member 150 to roll on the groove 80b of the inner boss 80 as a rolling surface 80f. 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.

Here, FIG. 12 shows an enlarged sectional view of one hole 88a of the outer boss 88 in the cam assist mechanism C. As shown in FIG. 12 is a cross-sectional view of a virtual plane perpendicular to the axis 20A of the crankshaft 20. As shown in FIG.

When the cam assist mechanism C is rotating with the crankshaft 20 in the direction of rotation R shown in FIGS. The rotation of the outer boss 88 is likely to be delayed. As a result, a force is applied to the ball member 150 from the inner boss 80, for example, a force F as shown in FIG. The force F can be divided into a normal load F1, a tangential load F2 perpendicular to it, 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 ball member 150 promotes movement of the ball member 150 along the rolling surface 80f of the groove 80b of the inner boss 80, thereby causing the outer boss 88 to move. are also encouraged to move together with the ball member 150 . Since the groove 80b of the inner boss 80 is helical as described above, the direction of this movement is opposite to the direction of rotation R as is apparent from FIGS. The direction is to the left in the axial direction. The direction to the left in the axial direction is the direction to the fixed drive pulley half 64a.

On the other hand, when the rotation of the crankshaft 20 is thus faster than before, input from the sensor detecting the rotation of the crankshaft 20, i.e., the crank angle sensor, causes the controller to cause the movable drive pulley half 64b to be fixedly driven. Motor 120 is activated to move closer to pulley half 64a. This movement of movable drive pulley half 64b relative to fixed drive pulley half 64a coincides with the aforementioned axial direction in which movement of outer boss 88 relative to inner boss 80 is urged. Accordingly, the cam assist mechanism C acts to assist the axial movement of the movable drive pulley half 64b by the motor 120 relative to the fixed drive pulley half 64a. That is, the cam assist mechanism C can assist the axial movement of the movable drive pulley half 64b integrated with the outer boss 88 by the rotational movement of the crankshaft 20. As shown in FIG.

This also occurs in the opposite direction when the rotation of the crankshaft 20 becomes slower than before. When the cam assist mechanism C is rotating together with the crankshaft 20 in the rotational direction R, if the rotation of the crankshaft 20 is slower than before, the rotation of the inner boss 80 is likely to lag behind 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. As a result, the outer boss 88 also moves together with the ball member 150. be encouraged to do so. Since the groove 80b of the inner boss 80 is helical as described above, the direction of movement at this time is the direction of rotation R as is clear from FIGS. The direction is to the right. Note that this direction to the right in the axial direction is the direction away from the fixed drive pulley half 64a. And when the rotation of the crankshaft 20 is thus slower than before, the input from the sensor detecting the rotation of the crankshaft 20 causes the controller to move the movable drive pulley half 64b from the fixed drive pulley half 64a. Operate the motor 120 away from the The movement of this movable drive pulley half 64b relative to the fixed drive pulley half 64a coincides with the aforementioned axial direction in which movement of the outer boss 88 relative to the inner boss 80 is urged, so that the movable drive pulley half by the motor 120 is aligned. Cam assist mechanism C acts to assist axial movement of body 64b relative to fixed drive pulley half 64a.

Therefore, compared to when the cam assist mechanism C is not provided, the output of the variable speed drive mechanism D that moves the movable drive pulley half 64b can be reduced. That is, less output of the motor 120 is required to move the movable drive pulley half 64b. This allows the motor 120 of the variable speed drive mechanism D to be made smaller.

In order to more favorably generate such assist in the cam assist mechanism C, the radial thickness 88t of the outer boss 88 is made equal to or greater than the radius of the ball member 150, and the ball member 150 is provided in the hole 88a with less clearance. Good. Also, the radius of curvature of the rolling contact surface 80f of each groove 80b is increased by 0.1 mm to 0.7 mm from the radius of curvature of the ball member 150, but the outer diameter of the inner boss 80 is reduced, that is, the radial thickness 80t is reduced. For example, by setting the depth 80d of the groove portion 80b of the inner boss 80 to a range of 20% to 45% of the diameter of the ball member 150, the normal load F1 can be reduced, and the ball member 150 and the rolling surface 80f clearance can be suppressed, so that the hammering sound generation toughness can be improved.

In addition, since the cam assist mechanism C is of the ball cam type, by changing the number of ball members 150 or the angle of the rolling surface, it is possible to easily adjust the assist capability, that is, the assist thrust force. Here, FIG. 13 simply shows the relationship between the groove portion 80b and the axis 20A in the inner boss 80 as seen from arrow XIII in FIG. In FIG. 13, the direction of the groove portion 80b, that is, the rolling contact surface 80f is schematically indicated by a line. In FIG. 13, the inclination angle θ of the groove portion 80b with respect to the axis 20A corresponds to the rolling surface angle. By changing the angle .theta. of the rolling surface, the assist ability can be changed.

Here, a sectional view of the right case 122a of the unit case 122 and its surroundings from the front of the vehicle is shown in FIG. 14, and a sectional view from the rear is shown in FIG. FIG. 16 shows the left side of the right side 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 circumferentially spaced apart on the inner surface of the right case 122a. Here, four stopper portions 122s are arranged at intervals of 90° (see FIG. 16). However, the number of stopper portions 122s is not limited to four, and should be at least one.

As shown in FIGS. 14 and 15, the right case 122a of the unit case 122 is provided with an extension pipe portion 154 extending axially outward, that is, to the right, toward the front portion 12a of the transmission case 12. extended. The extension tube portion 154 is provided so as to extend a hole 154h for communicating the inside and outside of the unit case 122 to the outside of the case 122. As shown in FIG. As shown in FIG. 16, the extension pipe portion 154 is positioned vertically above the right case 122a in the motorcycle 1 of FIG. As a result, it is possible for air to flow in and out between the unit case 122 and the power unit P. For example, the pumping load of the motor 120 can be reduced when the volume inside the unit case 122 increases or decreases due to gear shifting. At the same time, dew condensation within the unit case 122 can be suppressed. In addition, the inflow and outflow of the air can suitably cool the speed change drive mechanism D and the like.

In order to prevent water, oil, etc. from entering the unit case 122 through the extension tube portion 154, the cover portion 156 partially covers the outer inlet 154a of the extension tube portion 154. It is provided on the inner surface of the front portion 12a of the machine case 12 so as to hang down from above. The cover portion 156 has a plate shape and is formed so as to curve along the extending pipe portion 154 . In the belt chamber 14 inside the transmission case cover 16, as shown in FIG. It 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 tube portion 154. As shown in FIG. Therefore, when the cooling air comes near the outer inlet 154a of the extension tube portion 154, its flow is blocked by the cover portion 156 and passes through a labyrinth-shaped flow path formed around the cover portion 156. Fluids such as water and oil can be prevented from aggressively entering from the outer inlet 154a of the outlet pipe portion 154. As shown in FIG.

A drain tube 160, which is a member for draining water, is provided in a hole formed in the vertically lower portion of the unit case 122, that is, a drain hole 160h. Particularly here, a hole 160h connecting the inside and outside of the unit case 122 is formed at the bottom 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 portion is formed in the mating surfaces of the right case 122a and the left case 122b of the unit case 122 to form a labyrinth structure 160L. The drain tube 160 is made of resin, and has a substantially cylindrical base end 160a and a flat tip end 160b. In other words, the drain tube 160 functions as a drain member that allows water to flow out of the unit case 122 but prevents water from flowing into the unit case 122 via the drain tube 160 . Therefore, even if water enters the unit case 122, it may flow out of the unit case 122 from the drain tube 160 due to the change in volume inside the unit case 122 due to the shift, but it will flow back from the tip 160b of the drain tube 160. do not enter.

The transmission drive mechanism D and the cam assist mechanism C, which are integrated in the unit case 122 having the above configuration, are formed so that the hole portion of the inner boss 80 and the like are just fitted to 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 the crankshaft 20 is further inserted while rotating the screw member 134 into the female thread 142d of the movable holder 142. , the transmission drive mechanism D and the cam assist mechanism C integrated with the unit case 122 are attached to the front portion 12 a of the transmission case 12 . Unit case 122 is fixed to transmission case 12 with bolts 158 . As described above, the variable speed drive mechanism D and the cam assist mechanism C are excellent in mountability. The wall portion defining the shaft through hole 122i of the right case 122a is formed on the outer peripheral surface of the cylindrical portion 12c axially extending leftward in the front portion 12a of the transmission case 12 extending around the crankshaft 20. It is fitted through a sealing member.

According to the belt-type continuously variable transmission 10 described above, the following effects are achieved.

The variable speed drive mechanism D of the belt-type continuously variable transmission 10 is rotated by the rotation of the motor 120, extends in the axial direction, and has a screw member 134 that cannot move in the axial direction (impossible to move in the axial direction). and a movable holder 142 having an internal threaded portion 142d with which the screw member 134 is screwed and which is axially movable 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 is set to the drive pulley 64 in the radial direction of the crankshaft 20. can approach the position of the load applied to the belt 90 in (for example, the position of the V-belt 90 shown in FIGS. 4 and 5). Therefore, tilting of the movable drive pulley half 64b can be suppressed, and the size of the speed change drive mechanism D in the radial direction can be reduced, making it possible to reduce the size of the belt-type continuously variable transmission . Therefore, the belt-type continuously variable transmission 10 can be designed more freely.

In particular, the screw member 134 is positioned closer to the crankshaft 20 than the outer peripheral portion 64o of the movable drive pulley half 64b (see FIGS. 3 to 5). As a result, it is possible to suppress the tilting of the movable drive pulley half 64b and reduce the size of the transmission drive mechanism D in the radial direction more preferably. The outer peripheral portion 64o of the movable drive pulley half 64b is, for example, the outer peripheral surface of the movable drive pulley half 64b.

Further, the speed change drive mechanism D is provided in a unit case 122 in which a speed reduction mechanism 124 that accommodates the motor 120 and to which the driving force is transmitted by the motor 120 is provided, and extends in the radial direction of the unit case 122. A wall portion (case wall portion) 122g of 122 is provided in a state in which a screw member 134 is inserted. 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 receive radial and axial loads, and the bearing 138 is a thrust roller bearing and is configured to receive an axial load. Therefore, the radial load and axial load generated in the screw member 134 can be firmly received. Therefore, the size and weight of the belt-type continuously variable transmission 10 can be reduced by reducing the thickness of the unit case 122 and the like.

Further, the screw member 134 has a radially extending flange portion 134c, and the

bearings

136 and 138 sandwich the wall portion 122g with the flange portion 134c closer to the movable drive pulley half 64b than the wall portion 122g of the unit case 122. A nut 140, which is a fastening member that is screwed into the screw member 134, is located on the opposite side of the flange portion 134c. With this configuration, the removal toughness of the screw member 134 can be improved.

Further, the transmission drive mechanism D uses the outer peripheral surface 142c of the movable holder 142 as a sealing surface between the left side 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 screw portion 142d. With this configuration, compared to the case where the seal member is provided on the screw shaft, that is, the axis of the screw member 134, the amount of extension in the axial direction of the belt-type continuously variable transmission 10 can be shortened, and the entire unit including the variable speed drive mechanism D can also be reduced.

Also, a hole 154h is formed in the upper part of the unit case 122 in the vertical direction to allow the inside and outside of the case 122 to communicate with each other. As a result, it is possible to take air into the case 122 while suitably preventing water or the like from entering the unit case 122 . In addition, the hole 154h is provided at a position farther from the movable drive pulley half 64b than the movable holder in the axial direction, that is, provided on the back side of the unit case 122 here. In this way, the unit case 122 is provided with the hole 154h on the internal combustion engine E side. As a result, entry of dust and water into the unit case 122 through the hole 154h can be suppressed.

An extension pipe portion 154 is provided so as to extend the hole 154h to the outside of the unit case 122, and a cover portion 156 is provided so as to partially cover the outer inlet 154a of the extension pipe portion 154. Therefore, a labyrinth-like flow path can be formed around the cover portion 156 that partially covers the outer inlet 154a of the extending pipe portion 154, so that the flow from the outer inlet 154a of the extending pipe portion 154 into the unit case 122 can be formed. can prevent aggressive intrusion of fluids such as water and oil.

A drain hole 160h is formed in the vertically lower portion of the unit case 122, and a drain tube 160 is provided in the drain hole 160h as a drain member. Drain tube 160 has the above configuration. Therefore, even if water enters the unit case 122, the drainage performance of the unit case 122 can be ensured.

Further, the belt-type continuously variable transmission 10 has a cam 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 drive pulley half 64b by the speed change drive mechanism D. Equipped with assist mechanism C. As a result, the axial movement of the movable drive pulley half 64b by the speed change drive mechanism D can be favorably assisted.

The cam assist mechanism C is of the ball cam type, and includes an inner boss 80 provided so as to be rotatable integrally with the crankshaft 20, and along the outer peripheral surface 80a of the inner boss 80 together with the movable drive pulley half 64b. and an outer boss 88 axially moveable with the inner boss 80 and at least one ball member associated 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 .

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 arranged in the hole 88a of the outer boss 88, particularly the through hole here. Therefore, the number of constituent elements of the cam assist mechanism C can be reduced, and the cam assist mechanism C can be manufactured or processed at low cost.

The bottom of the hole 88a is defined by the inner race 144a of the bearing 144 held by the holding portion of the transmission drive mechanism D and the holding portion of the assist mechanism C. With this configuration, it is possible to suppress an increase in the number of parts of the cam assist mechanism C, and it becomes possible to form the hole portion 88a of the outer boss 88 more easily.

In addition, the disc spring 152 is provided as described above as a pressing member, that is, an elastic member, so as to press the ball member 150 toward the inner boss 80 (see FIGS. 4, 5 and 12). Therefore, it is possible to reduce the radial gap between the ball member 150 and the inner boss 80, thereby suppressing the hitting sound caused by the ball member 150 colliding with the inner boss 80 or the like.

Furthermore, the cam assist mechanism C is arranged between the speed change drive mechanism D and the movable drive pulley half 64b. Therefore, the cam assist mechanism C can more preferably assist the transmission of the driving force from the transmission drive mechanism D to the movable drive pulley half 64b.

A stopper portion 122s is provided on the inner surface of the right case 122a of the unit case 122 to restrict the movement of the movable drive pulley half 64b to the right in the axial direction when moving the movable drive pulley half 64b away from the fixed drive pulley half 64a. It is The movable holder 142 is formed so that the axial projection 142p on the outer peripheral side of the movable holder 142 can abut against the stopper portion 122s (see FIG. 4). On the other hand, when the movable drive pulley half 64b approaches the fixed drive pulley half 64a, the left side of the face surface of the movable drive pulley half 64b is adjusted so as to restrict the axial leftward movement of the movable drive pulley half 64b. can abut against the right axial end 64d of the face of the fixed drive pulley half 64a (see FIG. 5).

By the way, since the belt-type continuously variable transmission 10 of the above-described embodiment is applied to a small internal combustion engine E, the size of the power unit P is also small, and as shown in FIG. The centers of the two reduction gears 132 are not arranged in a straight line, but are arranged in a bent manner. This arrangement can be arbitrarily changed according to the dimensions of the power unit P.

An example of a belt-type continuously variable transmission applied to an internal combustion engine having a larger displacement than the internal combustion engine E to which the belt-type continuously variable transmission 10 is applied will be briefly described with reference to FIGS. 18 and 19. FIG. FIG. 18 is a cross-sectional view of a drive pulley 64 of a belt-type continuously variable transmission mounted thereon in a power unit having an internal combustion engine with a relatively large displacement and its surroundings. FIG. 19 is a diagram showing the gear arrangement of the speed change drive mechanism D1 in the belt type continuously variable transmission of FIG.

As shown in FIG. 19, the transmission drive mechanism D1 has the same configuration as the transmission drive mechanism D, but the relative arrangement of the motor 120, the first reduction gear 130, and the second reduction gear 132 is different from that of the transmission drive mechanism D. different from In the case of an internal combustion engine with a large displacement, the diameter of the drive pulley is larger than that of an internal combustion engine with a small displacement. Furthermore, in the transmission drive mechanism D1, the motor 120, the first reduction gear 130, A second reduction gear 132 is provided. In this way, the variable speed drive mechanisms D, D1 use the same motor 120, the same first reduction gear 130, and the same second reduction gear 132, and only by changing their arrangement, belts corresponding to various sizes of internal combustion engines can be provided. It can be applied to a type continuously variable transmission. The application of the same parts is the same for the cam assist mechanism C and the like as long as the input shaft of the same diameter, that is, the left extension of the crankshaft 20 is used.

In a belt-type continuously variable transmission applied to an internal combustion engine with a relatively large displacement, shown in FIG. A bearing 175 is provided which is At this time, the belt-type continuously variable transmission employs a floating structure using a grease-filled rubber bush 172 at the attachment portion of the right side case 122a to the front portion 12a of the transmission case 12. As shown in FIG. As a result, the reaction force in the axial direction on the crankshaft generated by the motor 120 is received by the stepped portion 76 at the end of the crankshaft. can be applied, and impact resistance and the like can be improved. In addition, it is possible to damp the rotational vibrations that occur with the vibrations of the engine and/or the vehicle body. 18, by fastening a bolt 186 to the left end surface of the crankshaft 20 through a washer 84, the fixed drive pulley half 64a and the like are fastened to the crankshaft 20, and they are integrated with the crankshaft 20. there is

In the belt-type continuously variable transmission shown in FIG. 18, as shown in FIG. 19, the hole 154h that communicates the inside and outside of the unit case 122 is provided with an extension tube portion 154 on the back side thereof. A cover portion 156 that partially covers the outer inlet 154a of the extension pipe portion 154 is provided on the inner surface of the front portion 12a of the transmission case 12 so as to hang down from above. Therefore, while preventing entry of water or the like into the unit case 122, the entry and exit of air inside and outside the unit case 122 is preferably allowed. Further, in the belt-type continuously variable transmission shown in FIG. 18, as shown in FIG. 19, a drain tube 160, which is a member for draining water, is provided in the hole 160h at the bottom in the vertical direction of the unit case 122, particularly in the hole 160h at the bottom. is provided. Therefore, the unit case 122 can ensure its drainage. 18 and 19, the hole 160h in the vertically lower portion of the unit case 122 is located between the right side case 122a and the left side case 122a of the unit case 122, as explained with reference to the cross-sectional view of FIG. It is formed on the mating surface with the case 122b to form a labyrinth structure 160L.

The belt-type continuously variable transmission shown in FIGS. 18 and 19 also has the same configuration as the belt-type continuously variable transmission 10, and has the various effects described above, but further explanation is omitted here. do.

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

Also, in the above embodiment, the cam assist mechanism is of the ball cam type, but other types of converting the rotational motion of the output shaft of the power source into the axial motion of the output shaft may be adopted. The mechanism (axial slide mechanism) for axially moving the movable drive pulley half 64b with respect to the fixed drive pulley half 64a by the operation of the drive mechanism is not limited to the cam assist mechanism C. For example, the drive mechanism It may be a mechanism that simply allows the movable drive pulley half 64b to move axially relative to the fixed drive pulley half 64a by the axial driving force of D, D1. Also, the power source may be other than the internal combustion engine.

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, C...Cam assist mechanism
D, D1...drive mechanism, E...internal combustion engine
P…Power unit

Claims

A belt (90) is stretched between a driving pulley (64) to which driving force is transmitted from the output shaft (20) of the power source and a driven pulley (94). A drive mechanism (D, D1) for generating axial driving force of the movable pulley half (64b) to move the movable pulley half (64b) with respect to (64a) includes a motor (120). A belt-type continuously variable transmission (10) comprising:
The drive mechanism (D, D1) is
a screw member (134) that is rotated by the rotation of the motor (120), extends in the axial direction, and is immovable in the axial direction;
a movable holder (142) having a female threaded portion (142d) into which the screw member (134) is screwed and which is movable in the axial direction together with the movable pulley half (64b),
A belt type continuously variable transmission (10) characterized in that the screw member (134) is positioned closer to the output shaft (20) than the outer peripheral portion (64o) of the movable pulley half (64b). .
The drive mechanism (D, D1) is provided in a case (122) that houses the motor (120) and is provided with a speed reduction mechanism (124) to which driving force is transmitted by the motor (120),
The screw member (134) is provided in a state of being inserted through a radially extending case wall (122g) of the case (122),
A first bearing (136) and a second bearing (138) are provided around the screw member (134) so as to sandwich the case wall (122g),
The first bearing (136) is configured to be able to receive radial and axial loads,
2. The belt-type continuously variable transmission (10) according to claim 1, wherein the second bearing (138) is configured to receive an axial load.
The screw member (134) has a radially extending flange portion (134c),
The first bearing (136) and the second bearing (138) are configured by the flange portion (134c) closer to the movable pulley half (64b) than the case wall portion (122g) and the case wall portion (122g). ) is sandwiched between the flange portion (134c) and a fastening member (140) located opposite to the screw member (134) and screwed into the screw member (134). type continuously variable transmission (10).
The drive mechanism (D, D1) is provided in a case (122) that houses the motor (120) and is provided with a speed reduction mechanism (124) to which driving force is transmitted by the motor (120),
The outer peripheral surface (142c) of the movable holder (142) serves as a sealing surface with the case (122),
The belt-type continuously variable transmission according to any one of claims 1 to 3, wherein a cap member (148) is provided on the movable pulley half (64b) side of the female threaded portion (142d). machine (10).
5. The belt type wireless belt according to any one of claims 2 to 4, characterized in that a hole (154h) for communicating the inside and outside of the case (122) is formed in the vertical upper part of the case (122). Stepped gearbox (10).
6. The belt-type pulley according to claim 5, wherein the hole (154h) is provided at a position further from the movable pulley half (64b) than the movable holder (142) in the axial direction. Continuously variable transmission.
An extension tube (154) is provided to extend the hole (154h) to the outside of the case (122),
7. The belt type continuously variable transmission according to claim 5 or 6, further comprising a cover portion (156) that partially covers the outer inlet (154a) of the extension tube portion (154). machine.
A drain hole (160h) is formed in the vertical lower part of the case (122),
The belt-type continuously variable transmission (10) according to any one of claims 2 to 7, wherein a water draining member (160) is provided in the water draining hole (160h).
The rotational motion of the output shaft (20) is controlled in the axial direction of the output shaft (20) so as to assist the axial movement of the movable pulley half (64b) by the drive mechanism (D, D1). The belt-type continuously variable transmission (10) according to any one of claims 1 to 8, further comprising a cam assist mechanism (C) for converting motion.
The cam assist mechanism (C) is of a ball cam type,
an inner member (80) provided so as to be rotatable integrally with the output shaft (20);
an outer member (88) movable in the axial direction along the outer peripheral surface of the inner member (80) together with the movable pulley half (64b);
10. The belt-type continuously variable transmission according to claim 9, further comprising at least one ball member (150) associated with said inner member (80) and said outer member (88). machine (10).