Belt-type continuously variable transmission

Abstract

Disclosed is a belt-type continuously variable transmission having improved assembling characteristics. By having a penetration rod (73) axially extending from a movable sheave (72) penetrate a fixed sheave (71) fixed to a shaft end of the output shaft (20), and by disposing, in an axially movable manner, a movable holder (93) having a cylindrical part (93a) that is pivotally supported, via a bearing (91), to a central shaft part (74b) of a rod end member (74) fixed to a rod end part (73e) that has protruded by the penetration, it is possible to dispose the movable holder (93) on the outer side of the drive pulley (70) in the vehicle width direction, and it is possible to reduce the size and weight of a belt-type continuously variable transmission (10) and avoid increase in the width of a vehicle overall without protruding the belt-type continuously variable transmission (10) outward in the vehicle width direction as a whole and without the need to largely displace a belt line outward in the vehicle width direction. In addition, it is possible to attach, from the outside in the vehicle width direction, a gear mechanism (96b, 96c), a screw mechanism (94b, 94c), etc., for transmitting the drive of an actuator (99b, 99c) to the movable holder (93).

Description

Technical Field

[0001] The present invention relates to a belt-type continuously variable transmission in which a belt is stretched between a driving pulley and a driven pulley for continuously variable transmission, and particularly to a belt-type continuously variable transmission mounted on a saddle-type vehicle.

Background Art

[0002] In a belt-type continuously variable transmission mounted on a saddle-type vehicle, a V-belt is stretched between a driving pulley to which the power of an internal combustion engine is transmitted and a driven pulley to which the power is transmitted to a driving wheel, and continuously variable transmission is achieved by changing the groove width of the pulley. To change the groove width of this pulley, there is an example (see, for example, Patent Document 1, etc.) in which the driving force of a motor as an actuator is used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0004] Patent Document 1 discloses a scooter-type motorcycle which is a saddle-type vehicle equipped with a power unit adopting a belt-type continuously variable transmission. The power unit, which is connected to the front part of the vehicle frame and supported so as to be swingable, has an internal combustion engine at the front part and a power transmission and transmission part which extends integrally from the left side of this internal combustion engine to the left side of the rear wheel in the rearward direction. A belt-type continuously variable transmission is housed in the belt chamber of this power transmission and transmission part.

[0005] A driving pulley provided on a crankshaft extending leftward from the crank chamber of the crankshaft of the internal combustion engine has a fixed sheave fixed to the left end of the crankshaft and a movable sheave axially supported so as to be axially movable on the right side of the fixed sheave, which are arranged facing each other. By the axial movement of the movable sheave, the distance from the fixed sheave changes, and the groove width of the driving pulley is changed.

[0006] As the groove width of the drive pulley changes, the winding diameter of the V-belt on the drive pulley changes, and consequently, the winding diameter on the driven pulley also changes, which automatically changes the gear ratio and results in stepless speed control. [Overview of the project] [Problems that the invention aims to solve]

[0007] The movable sheave has a cylindrical boss fixed to its central base, which is pivotally supported on the left side of the crankshaft so as to be movable in the axial direction. The cylindrical boss extends to the back side of the movable sheave, opposite to the V-belt contact surface, and the movable holder is attached to this extended portion of the cylindrical boss via rolling bearings.

[0008] The movable holder on the back side of the movable sheave is moved axially by the motor, causing the movable sheave to move axially along with it via the rolling bearing, changing the distance between it and the fixed sheave, thereby changing the speed ratio and enabling stepless speed control. Furthermore, a centrifugal thrust mechanism is provided on the right side of the movable holder, in which the weight roller moves due to centrifugal force, causing the movable sheave to move together with the movable holder.

[0009] In the belt-type continuously variable transmission disclosed in Patent Document 1, because there is a movable holder on the back side of the movable sheave that moves the movable sheave, the drive pulley protrudes to the left in the vehicle width direction. As a result, the belt line of the V-belt stretched between the drive pulley and the driven pulley is also significantly biased to the left side of the vehicle body. Overall, the belt-type continuously variable transmission protrudes outward in the vehicle width direction, increasing the overall width of the vehicle.

[0010] Furthermore, because the movable holder is located on the back side of the movable sheave, the transmission members that transmit the motor's drive to the movable holder must be installed by inserting them inward from the outside in the vehicle width direction, resulting in poor assembly.

[0011] The present invention has been made in view of the above, and its objective is to provide a compact, lightweight, and easy-to-assemble belt-type continuously variable transmission without requiring the belt-type continuously variable transmission to protrude outward from the vehicle width. And ultimately, this contributes to energy efficiency. [Means for solving the problem]

[0012] To achieve the above objective, the present invention A belt-type continuously variable transmission in which a V-belt is stretched between a drive pulley and a driven pulley, to which driving force is transmitted from the output shaft of a power source, The drive pulley consists of a fixed sheave fixed to the shaft end of the output shaft and a movable sheave that is pivotally supported on the output shaft so as to be movable in the axial direction and sandwiches the V-belt between itself and the fixed sheave. A through rod extending axially from the V-belt contact surface side of the axial center base of the movable sheave penetrates the axial center base of the fixed sheave. A rod end member is fixed to the rod end that protrudes through the axial center side base of the fixed sheave of the through rod, positioned on the extension of the output shaft. The rod end member has a central shaft portion that extends on the central axis of the output shaft in the direction opposite to the output shaft, A movable holder is provided so as to be movable in the axial direction, with a cylindrical portion pivotally supported on the central axis of the rod end member via a bearing. The present invention provides a belt-type continuously variable transmission comprising a screw mechanism in which a male screw member is screwed axially into a female screw portion provided in the movable holder, and a gear mechanism that transmits the drive of an actuator to the rotation of the male screw member.

[0013] In this configuration, a through rod extending axially from the axial center base of the movable sheave passes through the axial center base of the fixed sheave, which is fixed to the axial end of the output shaft. A movable holder is axially movable, with a cylindrical portion supported via a bearing on the central shaft of a rod end member that extends in the opposite direction to the output shaft, which is fixed to the rod end that has passed through and protruded. As a result, the movable holder can be positioned on the outside of the drive pulley in the vehicle width direction rather than on the inside. Therefore, it is not necessary to significantly displace the belt line of the V-belt stretched between the drive pulley and the driven pulley outwards in the vehicle width direction. Overall, this allows for miniaturization and weight reduction without protruding the belt-type continuously variable transmission outwards in the vehicle width direction, and consequently, avoids increasing the overall width of the vehicle. Furthermore, since the movable holder is positioned on the outside rather than the inside in the vehicle width direction of the drive pulley, the gear mechanism, screw mechanism, etc. that transmit the actuator's drive to the movable holder can be attached from the outside in the vehicle width direction, thus improving ease of assembly.

[0014] In a preferred embodiment of the present invention, The through rod consists of a pair of through rods that extend from the axial center base of the movable sheave and are formed symmetrically with respect to the central axis of the output shaft. The rod end members are fitted inside the pair of rod ends of the pair of through rods, A pin (75) is inserted into the rod end member along with the pair of rod ends, perpendicular to the central axis of the output shaft.

[0015] In this configuration, a rod end member is fitted inside a pair of rod ends of a pair of through rods that extend from the axial center base of the movable sheave and are formed symmetrically with respect to the central axis of the output shaft. A pin is inserted into the rod end member together with the pair of rod ends, perpendicular to the central axis of the output shaft, so the rod end member is fixed to the pair of rod ends by the pin. As a result, the rod end member is easy to attach and detach, maintainability is good, and when attached to the through rod, it can be firmly fixed.

[0016] In a preferred embodiment of the present invention, The pins penetrating the pair of rod ends are accommodated inside the outer periphery of the pair of rod ends. The rod cover member covers the outer periphery of the pair of rod ends.

[0017] According to this configuration, the pins penetrating the pair of rod ends are accommodated inside the outer periphery of the pair of rod ends, and the rod cover member covers the outer periphery of the pair of rod ends. Therefore, it has a simple structure that is easy to assemble. During assembly, etc., the rod cover member can prevent the pins penetrating the rod end members fitted therein together with the pair of rod ends from falling, and the assembly property is good.

[0018] In a preferred embodiment of the present invention, The movable holder has the female screw portion at an end of an arm portion extending from the cylindrical portion in a direction perpendicular to the central axis of the output shaft. The entire movable holder overlaps with the fixed sheave when viewed in the axial direction of the output shaft.

[0019] According to this configuration, the movable holder has the female screw portion at an end of an arm portion extending from the cylindrical portion in a direction perpendicular to the central axis of the output shaft, and the entire movable holder overlaps with the fixed sheave when viewed in the axial direction of the output shaft. Therefore, the movable holder can be made small and arranged compactly.

[0020] In a preferred embodiment of the present invention, The fixed sheave has a cylindrical extension portion extending to the back side opposite to the V-belt contact surface of the fixed sheave at the base on the shaft center side. A case member is attached to the outer periphery of the cylindrical extension portion of the fixed sheave via a bearing.

[0021] According to this configuration, the fixed sheave has a cylindrical extension portion extending to the back side opposite to the V-belt contact surface of the fixed sheave at the base on the shaft center side, and a case member is attached to the outer periphery of the cylindrical extension portion via a bearing. Therefore, even if an axial thrust is generated on the fixed sheave, it can be supported by the case member and the thrust acting on the output shaft can be suppressed.

[0022] In a preferred embodiment of the present invention, The transmission case cover covers the belt chamber, which houses the aforementioned belt-type continuously variable transmission, from the outside in the vehicle width direction. The case member is installed to the side of the transmission case cover using an elastic member interposed between the case member and the transmission case cover, and a positioning member that positions the case member relative to the transmission case cover.

[0023] In this configuration, the case member that receives the axial thrust of the fixed sheave is positioned relative to the transmission case cover by a positioning member and installed on the transmission case cover via an elastic member. Therefore, although the case member is installed on the transmission case cover, it is not fixed relative to the output axis, thus suppressing the generation of thrust on the output shaft.

[0024] In a preferred embodiment of the present invention, The actuator is positioned between the drive pulley and the driven pulley.

[0025] With this configuration, the actuator is positioned to effectively utilize the space between the drive pulley and the driven pulley, thereby suppressing the expansion of the belt-type continuously variable transmission in the vehicle width direction.

[0026] In a preferred embodiment of the present invention, On the back surface of the movable sheave opposite to the V-belt contact surface, a centrifugal thrust means is provided, which pushes the movable sheave toward the fixed sheave by the movement of a weight roller due to centrifugal force.

[0027] This configuration includes a centrifugal thrust mechanism using weight rollers, which can assist the thrust provided by the actuator. This allows for the use of a smaller output actuator, enabling a smaller and lighter belt-type continuously variable transmission. [Effects of the Invention]

[0028] In this invention, since the movable holder is positioned on the outside rather than the inside in the vehicle width direction of the drive pulley, the belt-type continuously variable transmission can be made smaller and lighter without protruding outwards in the vehicle width direction, and consequently, an increase in the overall width of the vehicle can be avoided. Furthermore, the gear mechanism and screw mechanism that transmit the actuator's drive to the movable holder can be attached from the outside in the vehicle width direction, improving ease of assembly. [Brief explanation of the drawing]

[0029] [Figure 1] This is a schematic diagram of the left side of a motorcycle equipped with a power unit featuring a belt-type continuously variable transmission according to one embodiment of the present invention. [Figure 2] This is a side view of the belt-type continuously variable transmission (CVT) section of the power unit. [Figure 3] This is a cross-sectional view of the power unit as seen from the line III-III in Figure 1. [Figure 4] This is an enlarged view of the main part of Figure 3. [Figure 5] This is a side view of the main front part of the power transmission unit with the transmission case cover and other covers removed. [Figure 6] This is a disassembled perspective view of the drive pulley. [Figure 7] This is a perspective view of the assembled drive pulleys, with a few exceptions. [Figure 8] This is a side view showing the assembled state of the drive pulley. [Figure 9] This is a cross-sectional view of the main part of a belt-type continuously variable transmission in another embodiment. [Modes for carrying out the invention]

[0030] Hereinafter, one embodiment of the present invention will be described with reference to Figures 1 to 8. Figure 1 is a schematic left side view of a motorcycle equipped with a power unit featuring a belt-type continuously variable transmission according to one embodiment of the present invention. In this specification, the forward, backward, left, and right directions will follow the usual standard where the forward direction of the motorcycle 1 according to this embodiment is considered to be forward. In the drawings, FR indicates the front, RR indicates the rear, LH indicates the left, and RH indicates the right.

[0031] 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 a low floor part 1c, and the vehicle frame that forms the skeleton of the vehicle body consists of a down tube 3 and a main pipe 4. Specifically, a down tube 3 extends downward from the head pipe 2 at the front of the vehicle body 1f, the down tube 3 bends horizontally at its lower end and extends rearward below the floor section 1c, and at its rear end a pair of left and right main pipes 4 are connected, and the main pipes 4 rise upward from the connection point, bend, and extend diagonally rearward.

[0032] The seat 5 is positioned above the main pipe 4. On the other hand, in the front part 1f of the vehicle body, the handlebars 6 are pivotally supported by the head pipe 2 and are mounted above, while the front fork 7 extends downward and the front wheel Wf is pivotally supported at its lower end. The motorcycle 1 has a power unit P mounted on it, supported by the main pipe 4. A main stand 8 is provided at the bottom of the power unit P, and it is adjustable in height.

[0033] The power unit P comprises a front internal combustion engine E and a power transmission unit T that extends integrally from the internal combustion engine E to the rear on the left side of the rear wheel Wr. As shown in Figure 3, the power transmission unit T comprises a transmission case 12 that extends integrally rearward from the internal combustion engine E, and a transmission case cover 16 that covers the transmission case 12 from the outside in the vehicle width direction, forming a belt chamber 14. A belt-type continuously variable transmission 10 is housed in the belt chamber 14. An outer cover 18 is provided on the left outer side of the transmission case cover 16 (see Figures 1 and 2).

[0034] The power source, the internal combustion engine E, is a single-cylinder, four-stroke internal combustion engine. The crankcase 22, which supports the crankshaft 20 oriented in the vehicle width direction, has a cylinder block 24, cylinder head 26, and cylinder head cover 28 that protrude forward and are tilted significantly to a nearly horizontal position.

[0035] A pair of left and right support brackets extend downward from the lower end of the crankcase 22. These support brackets are connected to a bracket 32 ​​projecting rearward from the lower front of the main pipe 4 via a link member 34, thereby pivotably connecting and supporting the power unit P to the vehicle body.

[0036] In the power unit P, the power transmission unit T, which extends rearward from the internal combustion engine E, has a rear axle 36, which is the output shaft of the reduction gear mechanism Tr located at its rear, and a rear wheel Wr, which is a drive wheel, attached to this axle. A rear cushion 9 is interposed between the support bracket 38, which is erected at the rear end of the power transmission unit T, and the rear of the main pipe 4.

[0037] An intake pipe 40 extends from the top of the significantly forward-tilted cylinder head 26 of the internal combustion engine E, curves backward, and reaches an air cleaner 44 above the power transmission unit T via a throttle body 42. Meanwhile, the exhaust pipe 46 extending downward from the lower part of the cylinder head 26 bends backward, is biased to the right, and extends rearward to connect to the muffler 48 on the right side of the rear wheel Wr.

[0038] Figure 3 shows a cross-sectional view of the power unit P along the line III-III in Figure 1. As shown in Figure 3, the crankcase 22 that supports the crankshaft 20 oriented in the vehicle width direction is formed by combining the right crankcase 22r and the front part 12a of the transmission case 12, which extends long from front to back on the left side.

[0039] The transmission case 12 has a rear section 12b that extends from the front section 12a to the left side of the rear wheel Wr, forming a long, oval-shaped opening to the left. A transmission case cover 16 is placed over the open left side of the transmission case 12, forming a belt chamber 14 inside, and as described above, the belt-type continuously variable transmission 10 is housed in this belt chamber 14. The right open surface of the rear 12b of the transmission case 12 is covered by a reduction gear cover 50, forming a reduction gear chamber 52 inside which the reduction gear mechanism Tr is housed. The power transmission section T is formed including the reduction gear mechanism Tr located at the rear 12b.

[0040] Within the so-called crankcase 22, formed by the fusion of the right crankcase 22r and the front part 12a of the transmission case 12, the crankshaft 20 is rotatably supported by the respective crank chamber side walls 22w, 12w of the right crankcase 22r and the front part 12a of the transmission case 12 via left and right metal bearings 54, 55. In the internal combustion engine E, a connecting rod 58 connects the piston 56, which reciprocates within the cylinder liner 24a of the cylinder block 24, to the crankpin 21 of the crankshaft 20.

[0041] A cam chain drive sprocket 60 is integrally and rotatably fitted to the right outer shaft portion of the crankshaft 20, which extends horizontally to the left and right, and an AC generator 62 is provided at its right end, while a drive pulley 70 for a belt-type continuously variable transmission 10 is provided on the left outer shaft portion. In other words, the crankshaft 20 is the output shaft of the internal combustion engine E, and the crankshaft 20, particularly its outer shaft portion, is the input shaft of the belt-type continuously variable transmission 10. The belt-type continuously variable transmission 10 is a continuously variable transmission in which a V-belt 100 is stretched between the front drive pulley 70 and the rear driven pulley 110.

[0042] The four-stroke internal combustion engine E of this embodiment employs a SOHC type valve system, with a valve train 66 provided inside the cylinder head cover 28, and a cam chain 68 that transmits power to the valve train 66 is installed between the camshaft 67 and the crankshaft 20.

[0043] Referring to Figure 4, the drive pulley 70 provided on the left outer shaft portion of the crankshaft 20 in the belt-type continuously variable transmission 10 of the power unit P consists of a fixed sheave 71 fixed to the shaft end of the crankshaft 20 and a movable sheave 72 that is pivotally supported on the crankshaft 20 so as to be movable in the axial direction. Referring to Figure 6 as well as Figure 4, the fixed sheave 71 has a cylindrical extended portion 71b that extends from the annular axial center base portion 71a to the back side opposite the conical V-belt contact surface 71f.

[0044] The movable sheave 72, which is opposite the fixed sheave 71, has a cylindrical extension portion 72b that extends from the annular axial center base portion 72a to the back side opposite the conical V-belt contact surface 72f (see Figure 4). A through rod 73, with its end embedded in the axial-center base 72a and the cylindrical extension 72b of the movable sheave 72, extends axially from the V-belt contact surface 72f side of the axial-center base 72a.

[0045] The through rod 73 consists of a pair of through rods 73, 73 that extend from the axial center side base 72a of the movable sheave 72 and are formed symmetrically with respect to the central axis, with respect to the central axis and having an arc-shaped cross-section. Circular holes 73h, 73h are drilled in the rod ends 73e, 73e of the pair of through rods 73, 73, at positions symmetrical with respect to the central axis.

[0046] When the movable sheave 72 is combined with the fixed sheave 71 with their respective V-belt contact surfaces 71f and 72f facing each other, a pair of through rods 73, 73 extending in the axial direction of the movable sheave 72 penetrate the axial center base 71a of the fixed sheave 71 (see Figures 4 and 7). Therefore, a pair of through holes 71h with a circular arc cross-section are formed in the axial-centered base portion 71a of the fixed sheave 71 (see Figure 4).

[0047] When the pair of through rods 73, 73 penetrate the axial base 71a of the fixed sheave 71, the rod ends 73e, 73e of the pair of through rods 73, 73 protrude from the cylindrical extension portion 71b of the fixed sheave 71. Rod end members 74 are fitted inside the rod ends 73e, 73e that protrude from the cylindrical extension portion 71b after passing through the axial center side base portion 71a of the fixed sheave 71 of the pair of through rods 73, 73. The rod end member 74 has a central shaft portion 74b that extends in the opposite direction to the movable sheave 72 on the central axis of the cylindrical body 74a that is fitted inside the rod ends 73e, 73e. The end of the central shaft portion 74b has a male thread 74c formed on it.

[0048] The cylindrical body 74a of the rod end member 74 has a through hole 74h perpendicular to the central axis. When the cylindrical body 74a is fitted into predetermined positions on the rod ends 73e, 73e of the pair of through rods 73, 73 in a predetermined position, the circular holes 73h, 73h of the pair of rod ends 73e, 73e coincide with the through hole 74h of the cylindrical body 74a of the rod end member 74. By inserting a cylindrical pin 75 perpendicular to the central axis through the circular holes 73h, 73h of the matching pair of rod ends 73e, 73e and the through hole 74h of the cylindrical body 74a of the rod end member 74, the rod end member 74 is fixed to the rod ends 73e, 73e of the pair of through rods 73, 73 (see Figures 4 and 7).

[0049] The pin 75, which penetrates the pair of rod ends 73e, 73e, fits inside the outer circumference of the pair of rod ends 73e, 73e. The rod cover member 76 covers the outer circumference of this pair of rod ends 73e, 73e. The rod cover member 76 has a cylindrical shaft portion 76b that extends outward on the central axis of the bottomed cylindrical body 76a, and whose inner diameter is approximately equal to the outer diameter of the central shaft portion 74b of the rod end member 74.

[0050] As shown in Figure 8, when the rod cover member 76 covers the outer circumference of the pair of rod ends 73e, 73e, the central shaft portion 74b of the rod end member 74, which is fitted inside the pair of rod ends 73e, 73e and fixed with a pin 75, passes through the cylindrical shaft portion 76b of the rod cover member 76, and the male thread 74c at the end protrudes.

[0051] The fixed sheave 71 and movable sheave 72, which are combined in this manner, are pivotally supported on the left side of the crankshaft 20. A centrifugal thrust mechanism 77 using weight rollers 78 is provided between the movable sheave 72, which is pivotally supported on the inside in the vehicle width direction, and the crank chamber side wall 12w of the front part 12a of the transmission case 12 (see Figure 4). As shown in Figure 4, the centrifugal thrust mechanism 77 consists of a weight roller 78 sandwiched between the reverse-tapered back surface of the movable sheave 72 and a holder plate 79 having a slanted surface. The weight roller 78 moves due to the centrifugal force generated by the rotation of the crankshaft 20, generating a force that pushes the movable sheave 72 toward the fixed sheave 71.

[0052] Referring to Figure 4, the holder plate 79 is fitted onto the left side portion of the crankshaft 20, which extends to the left of the stepped portion 20d to the left of the crank chamber side wall 12w, and then the cylindrical collar member 80 and washer 81 are fitted onto it. Then, when the drive pulley 70, which is formed by passing a pair of through rods 73, 73 through the axial-center base 71a of the fixed sheave 71 and combining the movable sheave 72 with the fixed sheave 71, is fitted to the left side of the crankshaft 20, the axial-center base 72a of the movable sheave 72 is fitted to the collar member 80 so as to be axially movable but not relative to it, and the axial-center base 71a of the fixed sheave 71 is spline-fitted to the end of the crankshaft 20 that protrudes from the collar member 80 on the left side.

[0053] The shaft-center side base 71a of the fixed sheave 71, which is spline-fitted to the left end of the crankshaft 20, abuts against a washer 81. A washer 82 is placed against the side surface of the shaft-center side base 71a, and the washer 82, washer 81, collar member 80, and holder plate 79 are tightened between the stepped portion 20d of the crankshaft 20 by a bolt 83 that is screwed into the left end face of the crankshaft 20, thereby fixing the fixed sheave 71 to the left end of the crankshaft 20.

[0054] The movable sheave 72, together with a pair of through rods 73, 73, is pivotally supported on the left side of the crankshaft 20 so as to be axially movable on the collar member 80. A V-belt 100 is placed between the fixed sheave 71 and the movable sheave 72. As described above, the rod ends 73e, 73e that protrude from the cylindrical extension portion 71b after passing through the axial center side base portion 71a of the fixing sheave 71 of the pair of through rods 73, 73 are fitted with rod end members 74 and fixed by pins 75, and the bottomed cylindrical body 76a of the rod cover member 76 covers the outer circumference of the pair of rod ends 73e, 73e.

[0055] As shown in Figure 4, the cylindrical extension portion 71b of the fixed sheave 71 protrudes to the left through the opening of the transmission case cover 16, and the cylindrical portion 17a of the case member 17 passes through the opening to the right. A rolling bearing 85 is interposed between the cylindrical portion 17a and the cylindrical extension portion 71b of the fixed sheave 71 inside it. A case member 17 is attached to the fixed sheave 71 via a rolling bearing 85 on the outer circumference of the cylindrical extended portion 71b.

[0056] Referring to Figure 4, the case member 17 is installed on the side wall around the opening of the transmission case cover 16 via a rubber member (elastic member) 87. A positioning pin (positioning member) 88, oriented in the left-right direction, penetrates the rubber member 87, with its right side fitted into the transmission case cover 16 and its left side fitted into the case member 17, thereby positioning the case member 17 relative to the transmission case cover 16. The case member 17 is positioned relative to the transmission case cover 16 by positioning pins 88 and installed on the transmission case cover 16 via a rubber member 87.

[0057] A pair of rod ends 73e, 73e protrude to the left of the case member 17, each having a rod end member 74 and a rod cover member 76. The central case cover member 19a covers the left side of the case member 17 on which the rod end member 74 and rod cover member 76 are disposed, the first case cover member 19b covers the left side of the portion of the transmission case cover 16 that is rear of the case member 17, and the second case cover member 19c covers the left side of the portion of the transmission case cover 16 that is upper than the case member 17, thereby forming a transmission drive chamber 90c in which the transmission drive mechanism 90 is housed.

[0058] Figure 5 is a side view showing the main part of the front portion of the power transmission unit T, with the central case cover member 19a, the first and second case cover members 19b and 19c removed from the transmission case cover 16 along with the outer cover 18. Referring to Figures 5 and 4, the central cylindrical portion 93a of the movable holder 93 is fitted onto a rolling bearing 91 provided on the outer circumference of the cylindrical shaft portion 76b of the rod cover member 76 that covers the central shaft portion 74b of the rod end member 74, so that the movable holder 93 is movable in the axial direction.

[0059] In other words, since the movable holder 93 is pivotally supported on the central shaft portion 74b of the rod end member 74 via a rolling bearing 91, when the movable holder 93 moves in the axial direction, the rod end member 74 and the pair of through rods 73, 73 integrated with it, as well as the fixed sheave 71, which rotate relatively via the rolling bearing 91, can all move in the axial direction.

[0060] Furthermore, the inner race of the rolling bearing 91, which is provided on the outer circumference of the cylindrical shaft portion 76b of the rod cover member 76, is tightened and fixed by a nut 92 that is screwed onto the male thread 74c at the end of the central shaft portion 74b of the rod end member 74, which protrudes to the left of the cylindrical shaft portion 76b.

[0061] As shown in Figure 5, the movable holder 93 has a central cylindrical portion 93a supported by a rolling bearing 91, a first arm portion 93b extending slightly diagonally upward and backward in a direction perpendicular to the central axis of the crankshaft 20, and a second arm portion 93c extending slightly diagonally forward and upward. Female threads are formed at the female thread portion 94bf at the end of the first arm portion 93b and at the female thread portion 94cf at the end of the second arm portion 93c. As shown in Figure 5, the movable holder 93 is entirely aligned with the fixed sheave 71 in an axial view of the crankshaft 20.

[0062] The first screw mechanism 94b is formed by screwing the male screw member 94bm into the female screw portion 94bf of the first arm portion 93b, and the second screw mechanism 94c is formed by screwing the male screw member 94cm into the female screw portion 94cf of the second arm portion 93c.

[0063] Referring to Figure 4, the male threaded member 94bm of the first screw mechanism 94b is rotatably mounted between the case member 17 and the central case cover member 19a via bearings 95, 95, oriented in the vehicle width direction, and the central male thread is screwed into the female threaded portion 94bf of the first arm portion 93b of the movable holder 93. A large-diameter reduction gear 96bb is fitted near the right end of the male threaded member 94bm.

[0064] The first drive motor 99b is mounted behind the drive pulley 70 and in front of the driven pulley 110, with the drive shaft 99ba protruding to the left from the transmission case cover 16. In other words, the first drive motor 99b is positioned between the drive pulley 70 and the driven pulley 110. A drive gear 99bs is formed on the drive shaft 99ba. In front of the drive gear 99bs, a reduction gear shaft 97b oriented in the vehicle width direction is mounted between the first case cover member 19b and the transmission case cover 16 via bearings 98, 98.

[0065] A large-diameter reduction gear 97bb, integrated with the reduction gear shaft 97b, meshes with the drive gear 99bs of the first drive motor 99b, and a small-diameter reduction gear 97bs, also integrated with the reduction gear shaft 97b, meshes with a large-diameter reduction gear 96bb, integrated with the male screw member 94bm. The first reduction gear mechanism 96b is configured such that the drive gear 99bs of the first drive motor 99b meshes with the large-diameter reduction gear 97bb of the reduction gear shaft 97b to perform the first stage of reduction, and the small-diameter reduction gear 97bs of the reduction gear shaft 97b meshes with the large-diameter reduction gear 96bb of the male screw member 94bm to perform the second stage of reduction.

[0066] Therefore, when the first drive motor 99b is driven and rotates the drive gear 99bs, the male screw member 94bm is rotated at a reduced speed via the first reduction gear mechanism 96b, and the rotation of the male screw member 94bm causes the movable holder 93 to move axially via the first screw mechanism 94b, and together with the movable holder 93, the movable sheave 72 can move axially via the rod end member 74 and the through rod 73.

[0067] Similarly, a large-diameter reduction gear 96cb is fitted to a male threaded member 94cm that screws into the female threaded portion 94cf of the second arm portion 93c extending diagonally upward from the movable holder 93. A second drive motor 99c is provided above the drive pulley 70, and a drive gear 99cs is formed on its drive shaft 99ca. Below the drive gear 99cs, a reduction gear shaft 97c, oriented in the vehicle width direction, is rotatably mounted between the second case cover member 19c and the transmission case cover 16.

[0068] A large-diameter reduction gear 97cb, integrated with the reduction gear shaft 97c, meshes with the drive gear 99cs of the second drive motor 99c, and a small-diameter reduction gear 97cs, also integrated with the reduction gear shaft 97c, meshes with a large-diameter reduction gear 96cb, integrated with the male screw member 94cm. The second reduction gear mechanism 96c is configured such that the drive gear 99cs of the second drive motor 99c meshes with the large-diameter reduction gear 97cb of the reduction gear shaft 97c to perform the first stage of reduction, and the small-diameter reduction gear 97cs of the reduction gear shaft 97c meshes with the large-diameter reduction gear 96cb of the male screw member 94cm to perform the second stage of reduction.

[0069] Therefore, when the second drive motor 99c is driven and rotates the drive gear 99cs, the male screw member 94cm is rotated at a reduced speed via the second reduction gear mechanism 96c, and the rotation of the male screw member 94cm causes the movable holder 93 to move axially via the second screw mechanism 94c. As mentioned above, the movable holder 93 can also be moved axially by the drive of the first drive motor 99b, so the first drive motor 99b and the second drive motor 99c work together to move the movable holder 93 axially, and together with the movable holder 93, the movable sheave 72 of the drive pulley 70 can be moved axially via the rod end member 74 and the through rod 73.

[0070] Furthermore, the drive motor may be a single unit, in which case the belt-type continuously variable transmission can be miniaturized by using a first drive motor 99b positioned between the drive pulley 70 and the driven pulley 110.

[0071] The driven pulley 110, which is rotatably supported on the driven shaft 120, which is the input shaft of the reduction gear mechanism Tr, behind the drive pulley 70, comprises a fixed sheave 111 and a movable sheave 112 that is movable in the axial direction and faces the fixed sheave 111 on its left side. An inner sleeve 116 is pivotally supported on the driven shaft 120 via a bearing, with its axial movement restricted, allowing it to rotate relative to the shaft. A fixed sheave 111 is integrally fixed to the right end flange of the inner sleeve 116 by welding its central hole.

[0072] An outer sleeve 118 is fitted around the outer circumference of the inner sleeve 116 of the fixed sheave 111. Guide pins protruding from the inner sleeve 116 are fitted into elongated holes formed in the outer sleeve 118 in the axial direction, allowing the outer sleeve 118 to move relative to the inner sleeve 116 in the axial direction, but restricting relative rotation.

[0073] The movable sheave 112 is integrally fixed to the right end flange of the outer sleeve 118 by welding its central hole. Therefore, the movable sheave 112 rotates with the fixed sheave 111, but can move axially relative to the fixed sheave 111 to approach or move away from it.

[0074] The clutch inner 132 of the centrifugal clutch 130 is fixed to the left end of the inner sleeve 116 by a nut, and a coil spring 131 is interposed between the clutch inner 132 and the movable sheave 112, biasing the movable sheave 112 to the right by the coil spring 131.

[0075] In the belt-type continuously variable transmission 10, power is transmitted by a V-belt 100 stretched between the drive pulley 70 and the driven pulley 110. In the belt-type continuously variable transmission 10, as described above, the first drive motor 99b and the second drive motor 99c work together to move the movable holder 93 in the axial direction, and together with the movable holder 93, move the movable sheave 72 of the drive pulley 70 in the axial direction, changing the distance between it and the fixed sheave 71. As a result, the winding diameter of the V-belt 100 on the drive pulley 70 changes, and simultaneously the winding diameter on the driven pulley 110 changes, which automatically changes the gear ratio and enables continuously variable speed control.

[0076] In this embodiment, the belt-type continuously variable transmission 10 is equipped with a centrifugal thrust mechanism 77, which applies a force that pushes the movable sheave 72 toward the sheave 71 according to the engine speed. This assists the thrust provided by the first drive motor 99b and the second drive motor 99c, allowing for the use of motors with smaller output and enabling the belt-type continuously variable transmission 10 to be made smaller and lighter.

[0077] The centrifugal clutch 130 has a bowl-shaped clutch outer 134 that covers the outer circumference of the clutch inner 132, with its base fixed near the left end of the driven shaft 120, and a clutch shoe 133 that is pivotally supported on the clutch inner 132 by a spring 138 and biased to swing freely is disposed opposite the inner surface of the clutch outer 134. The clutch inner 132 of the centrifugal clutch 130 rotates together with the continuously variable driven pulley 110 of the belt-type continuously variable transmission 10. When the rotational speed exceeds a predetermined speed, the clutch shoe 133 of the clutch inner 132 oscillates against the spring 138 due to centrifugal force and contacts the inner circumferential surface of the clutch outer 134, causing the clutch outer 134 to rotate together with the clutch outer 134 and transmitting power to the driven shaft 120.

[0078] The driven shaft 120 is supported via bearings by the transmission case cover 16, the rear part 12b of the transmission case 12, and the reduction gear cover 50, and extends to both the belt chamber 14 and the reduction gear chamber 52. In the reduction gear mechanism Tr within the reduction gear chamber 52, a reduction intermediate shaft 141 is mounted and supported on the transmission case 12 and the reduction gear cover 50, with the shafts oriented parallel to each other (horizontally from left to right) between the driven shaft 120 and the rear axle 36, and the reduction gear mechanism Tr is composed of gears on each shaft. Therefore, the rotation of the driven shaft 120 is reduced via the reduction gear mechanism Tr and transmitted to the rear axle 36, causing the rear wheel Wr to rotate.

[0079] The embodiment of the belt-type continuously variable transmission according to the present invention, as described in detail above, provides the following effects. Referring to Figures 3 and 4, a pair of through rods 73, 73 extending axially from the axial center base 72a of the movable sheave 72 pass through the axial center base 71a of the fixed sheave 71, which is fixed to the axial end of the crankshaft 20. A movable holder is axially movable, with a central cylindrical portion 93a supported via a rolling bearing 91 on a central shaft portion 74b of a rod end member 74 that extends in the opposite direction to the crankshaft 20, which is fixed to the rod ends 73e, 73e that have passed through and protruded. As a result, the movable holder 93 can be positioned on the outside of the drive pulley 70 in the vehicle width direction rather than on the inside. Therefore, it is not necessary to significantly displace the belt line of the V-belt 100, which is stretched between the drive pulley 70 and the driven pulley 110, outward in the vehicle width direction. This allows for miniaturization and weight reduction of the belt-type continuously variable transmission 10 without it protruding outward in the vehicle width direction, and consequently, avoids increasing the overall width of the vehicle.

[0080] Furthermore, since the movable holder 93 is positioned on the outside rather than the inside in the vehicle width direction of the drive pulley 70, the first and second reduction gear mechanisms 96b, 96c and the first and second screw mechanisms 94b, 94c, etc., which transmit the drive of the first and second drive motors 99b, 99c to the movable holder 93, can be attached from the outside in the vehicle width direction, thus improving ease of assembly.

[0081] As shown in Figure 7, the rod end member 74 is fitted into a pair of rod ends 73e, 73e of a pair of through rods 73, 73 that extend from the axial center base 72a of the movable sheave 72 and are formed symmetrically with respect to the central axis of the crankshaft 20. The rod end member 74 is fixed to the pair of rod ends 73e, 73e by a pin 75 that penetrates perpendicular to the central axis of the crankshaft 20. Therefore, the rod end member 74 is easy to attach and detach, maintainability is good, and when attached to the pair of through rods 73, 73, it can be firmly fixed.

[0082] Referring to Figures 7 and 8, the pins 75 that are inserted into the pair of rod ends 73e, 73e are housed inside the outer circumference of the pair of rod ends 73e, 73e, and the rod cover member 76 covers the outer circumference of the pair of rod ends 73e, 73e, resulting in a simple structure that is easy to assemble. The rod cover member prevents the pins that are inserted into the rod end members fitted inside the pair of rod ends from falling out during assembly, resulting in good assembly performance.

[0083] The movable holder 93 has female threaded portions 94bf and 94cf at the ends of arms 93b and 93c that extend from the central cylindrical portion 93a in a direction perpendicular to the central axis of the crankshaft 20, and the entire structure overlaps with the fixed sheave 71 when viewed in the axial direction of the crankshaft 20, so the movable holder 93 can be made small and compactly installed, and the size of the belt-type continuously variable transmission can be avoided.

[0084] Referring to Figures 4 and 6, the fixed sheave 71 has a cylindrical extension portion 71b extending from the axial center side base portion 71a to the back side opposite to the V-belt contact surface 71f of the fixed sheave 71, and a case member 17 is attached to the outer circumference of the cylindrical extension portion 71b via a rolling bearing 85. Therefore, even if an axial thrust is generated in the fixed sheave 71, it is supported by the case member 17 and thrust acting on the crankshaft 20 can be suppressed. As in this embodiment, when the crankshaft 20 is supported by metal bearings 54 and 55 on the crank chamber side walls 22w and 12w and there is no thrust bearing, it is effective to suppress the thrust acting on the crankshaft 20.

[0085] In this embodiment, the case member 17 that receives the axial thrust of the fixed sheave 71 is positioned relative to the transmission case cover 16 by a positioning pin 88 and installed on the transmission case cover 16 via a rubber member 87. Therefore, although the case member 17 is installed on the transmission case cover 16, it is not fixed relative to the output axis direction, thus suppressing the generation of thrust on the output shaft 20. Therefore, this embodiment is applicable regardless of whether or not the crankshaft 20 has a thrust bearing.

[0086] Referring to Figure 3, the first drive motor 99b is positioned to make effective use of the space between the drive pulley 70 and the driven pulley 110, thereby preventing the belt-type continuously variable transmission 10 from expanding.

[0087] As shown in Figure 4, the system also has a centrifugal thrust means 77 using weight rollers 78, which can assist the thrust from the first and second drive motors 99b and 99c, allowing for the use of drive motors with smaller output and enabling the belt-type continuously variable transmission 10 to be made smaller and lighter.

[0088] Next, a belt-type continuously variable transmission according to another embodiment will be described with reference to Figure 9. In the above-described embodiment, the crankshaft 20 is supported by metal bearings 54 and 55 on the crank chamber side walls 22w and 12w, so a case member 17 is attached to the fixed sheave 71 via a rolling bearing 85 to suppress thrust acting on the crankshaft 20. However, if there is something to receive the thrust of the crankshaft, it is not necessary to attach a case member or the like to the fixed sheave, and this embodiment shows an example of a belt-type continuously variable transmission in which such a fixed sheave does not have a case member or the like attached. The other structural features are the same as those of the previously described embodiment.

[0089] Figure 9 is a cross-sectional view of the front portion of the belt-type continuously variable transmission 10' of this embodiment. Components that are the same as those in the previously described embodiment or components that perform the same function will be given the same reference numerals as those used in the previously described embodiment.

[0090] The crankshaft 20 is supported by rolling bearings 55' on the crankcase side walls 22w and 12w, and the thrust acting on the crankshaft 20 can be absorbed by the rolling bearings 55'. The fixed sheave 71' of the drive pulley 70 has a cooling fan 71c' on its rear and is originally shaped in a way that makes it difficult to attach a case component, so no component equivalent to a case component is attached. The case member 17', which corresponds to the case member 17 in the above-described embodiment, is not attached to the fixed sheave 71', but is used as a support member to pivotally support the male screw member 94bm and the reduction gear shaft 97b of the variable speed drive mechanism 90, and to hold the first drive motor 99b. Furthermore, the fixed sheave 71' is secured to the crankshaft 20 by a nut 83'.

[0091] Although a belt-type continuously variable transmission according to an embodiment of the present invention has been described above, the embodiments of the present invention are not limited to the above embodiments and include a variety of embodiments that can be implemented within the scope of the gist of the present invention. [Explanation of symbols]

[0092] P...Power unit, E...Internal combustion engine, T...Power transmission unit 10... Belt-type continuously variable transmission, 12... Transmission case, 14... Belt chamber, 16... Transmission case cover, 17... Case member, 18... Outer cover, 19a... Central case cover member, 19b... First case cover member, 19c... Second case cover member, 20...Crankshaft, 22...Crankcase, 50...Reduction gear cover, 52...Reduction gear chamber, 54, 55...Metal bearings 70... Drive pulley, 71... Fixed sheave, 71a... Shaft center side base, 71b... Cylindrical extension part 72b, 72... Movable sheave, 72a... Shaft center side base, 72b... Cylindrical extension part 72b, 73... Through rod, 73e... Rod end, 74... Rod end member, 74b... Central shaft part, 75... Pin, 76... Rod cover member, 77... Centrifugal thrust mechanism, 78... Weight roller, 79... Holder plate, 85... Rolling bearing, 87... Rubber member, 88... Positioning pin, 90...Variable speed drive mechanism, 91...Rolling bearing, 92...Nut, 93...Movable holder, 93a...Central cylindrical part, 93b...First arm part, 93c...Second arm part, 94b...First screw mechanism, 94bf...Female screw portion, 94bm...Male screw member, 94c...Second screw mechanism, 94cf...Female screw part, 94cm...Male screw member, 95...Bearing 96b...First reduction gear mechanism, 96bb...Large diameter reduction gear, 97b...Reduction gear shaft, 97bb...Large diameter reduction gear, 97bs...Small diameter reduction gear, 98...Bearing 96c...Second reduction gear mechanism, 96cb...Large diameter reduction gear, 97c...Reduction gear shaft, 97cb...Large diameter reduction gear, 97cs...Small diameter reduction gear, 99b...First drive motor, 99bs...Drive gear, 99c...Second drive motor, 99cs...Drive gear, 100...V-belt, 110...Driven pulley, 111...Fixed sheave, 112...Movable sheave, 116...Inner sleeve, 118...Outer sleeve, 120...Driven shaft, 130...Centrifugal clutch.

Claims

1. A belt-type continuously variable transmission (10) in which a V-belt (100) is stretched between a drive pulley (70) and a driven pulley (110) that receive driving force from the output shaft (20) of a power source, The drive pulley (70) consists of a fixed sheave (71) fixed to the shaft end of the output shaft (20) and a movable sheave (72) that is pivotally supported on the output shaft (20) so as to be movable in the axial direction and sandwiches the V-belt (100) between itself and the fixed sheave (71). A through rod (73) extending axially from the V-belt contact surface (72f) side of the axial center side base (72a) of the movable sheave (72) penetrates the axial center side base (71a) of the fixed sheave (71). A rod end member (74) is fixed to the rod end (73e) of the through rod (73) that protrudes through the axial center side base (71a) of the fixed sheave (71), positioned on the extension of the output shaft (20). The rod end member (74) has a central shaft portion (74b) that extends on the central axis of the output shaft (20) in the direction opposite to the output shaft (20), A movable holder (93) is provided so as to be movable in the axial direction, with a cylindrical portion (93a) pivotally supported on the central shaft portion (74b) of the rod end member (74) via a bearing (91). A belt-type continuously variable transmission characterized by comprising a screw mechanism (94b) in which a male screw member (94bm) is screwed axially into a female screw portion (94bf) provided on the movable holder (93), and a gear mechanism (96b) that transmits the drive of an actuator (99b) to the rotation of the male screw member (94bm).

2. The through rod (73) consists of a pair of through rods (73,73) that extend from the axial center side base (72a) of the movable sheave (72) and are formed symmetrically with respect to the central axis. The rod end member (74) is fitted inside the pair of rod ends (73e, 73e) of the pair of through rods (73, 73), The belt-type continuously variable transmission according to claim 1, characterized in that a pin (75) is inserted into the rod end member (74) together with a pair of rod ends (73e, 73e) perpendicular to the central axis of the output shaft (20).

3. The pin (75) that penetrates the pair of rod ends (73e, 73e) is located inside the outer circumference of the pair of rod ends (73e, 73e), The belt-type continuously variable transmission according to claim 2, characterized in that a rod cover member (76) covers the outer circumference of a pair of rod ends (73e, 73e).

4. The movable holder (93) has the female thread portion (94bf) at the end of the arm portion (93b) that extends from the cylindrical portion (93a) in a direction perpendicular to the central axis of the output shaft (20), The belt-type continuously variable transmission according to claim 1, characterized in that the movable holder (93) as a whole overlaps with the fixed sheave (71) in an axial view of the output shaft (20).

5. The fixed sheave (71) has a cylindrical extended portion (71b) at its axial center side base (71a) that extends to the back side opposite to the V-belt contact surface (71f) of the fixed sheave (71), The belt-type continuously variable transmission according to claim 1, characterized in that a case member (17) is attached to the fixed sheave (71) via a bearing (85) on the outer circumference of the cylindrical extension portion (71b).

6. The transmission case cover (16) covers the belt chamber (14) in which the belt-type continuously variable transmission (10) is housed from the outside in the vehicle width direction. The belt-type continuously variable transmission according to claim 5, characterized in that the case member (17) is installed to the side of the transmission case cover (16) using an elastic member (87) interposed between the case member (17) and the transmission case cover (16) and a positioning member (88) for positioning the case member (17) relative to the transmission case cover (16).

7. The belt-type continuously variable transmission according to claim 1, characterized in that the actuator (99b) is arranged between the drive pulley (70) and the driven pulley (110).

8. The belt-type continuously variable transmission according to claim 1, characterized in that a centrifugal thrust mechanism (77) is provided on the back surface of the movable sheave (72) opposite to the V-belt contact surface (72f), such that a weight roller (78) moves by centrifugal force, pushing the movable sheave (72) toward the fixed sheave (71).

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