belt drive

Abstract

The belt drive device (40) of the present invention is easy to adjust the belt tension and is compactly arranged, including: a belt (43) rotatably wound around a drive pulley (41) and a driven pulley (42); and a tensioner (44) for applying tension to the belt. The tensioner includes: a tensioner base (51) disposed on the axial side of the belt's rotation; a tensioner arm (61) pivotally supported on the tensioner base; a tensioner roller (66) rotatably supported on the tensioner arm; and a tensioner spring (67) elastically connected to the tensioner arm. The tensioner spring's elastic force is applied to the tensioner arm in the direction in which the tensioner roller presses against the belt. The tensioner roller is located radially outward of the belt's rotation, and the tensioner spring is located radially inward of the belt's rotation.

Description

Technical Field

[0001] This invention relates to belt drive devices. Background Technology

[0002] Conventionally, belt drive devices are known to transmit power from an output shaft connected to a drive source to a drive pulley via a belt (see, for example, Patent Document 1). In the belt drive device described in Patent Document 1, a drive pulley is fixed to the output shaft, a driven pulley is fixed to the drive pulley, and a belt is wound around both the drive pulley and the driven pulley. Power is transmitted by the difference between the tension of the belt stretched by the driven pulley and the tension of the belt returning to the drive pulley. Furthermore, rollers are provided around the drive pulley to prevent the belt from lifting.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent document 1: Japanese Patent No. 4197067.

[0006] The problem that the invention aims to solve

[0007] However, in belt drives, belt tension is adjusted by changing the spacing of pulleys, using idle rollers, or tensioners. When changing the pulley spacing or using idle rollers, the belt length varies depending on usage, thus requiring regular tension checks and adjustments, demanding specialized equipment and maintenance skills. When adjusting the belt length using tensioners, ample space must be ensured. Summary of the Invention

[0008] The present invention was made in view of the above-mentioned problems, and its object is to provide a belt drive device that can easily adjust the belt tension and can be compactly arranged.

[0009] Methods for solving problems

[0010] One aspect of the belt drive device of the present invention comprises: a belt configured to rotate wound around a drive pulley and a driven pulley; and a tensioner configured to apply tension to the belt, the tensioner comprising: a tensioner base disposed to the side of the belt in the axial direction of rotation of the belt; a tensioner arm pivotally supported on the tensioner base; a tensioner roller rotatably supported on the tensioner arm; and a tensioner spring elastically connected to the tensioner arm, the tensioner spring being configured to apply a spring force to the tensioner arm in the pressing direction in which the tensioner roller presses against the belt, the tensioner roller being located radially outward relative to the belt in the direction of rotation of the belt, and the tensioner spring being located radially inward relative to the belt.

[0011] Invention Effects

[0012] According to one aspect of the belt drive device of the present invention, the tensioner arm swings by the elastic force of the tensioner spring, and the tensioner roller supported on the tensioner arm presses against the belt. Since the belt tension is automatically adjusted, belt adjustment work is eliminated, improving assembly efficiency, and even if the belt extends its entire length, periodic retensioning is not required, improving maintainability. Furthermore, by maintaining the belt at appropriate tension, belt fatigue can be reduced, extending its lifespan. Even with such an automatic tensioner, the tensioner roller and tensioner spring can be separately installed inside and outside the belt, thereby preventing the belt drive device from becoming too large. Attached Figure Description

[0013] Figure 1 This embodiment shows a left-side view of a straddle-type vehicle.

[0014] Figure 2 This is a side view of the swing arm in this embodiment.

[0015] Figure 3 It is cut along line AA Figure 2 A cross-sectional view of the swing arm.

[0016] Figure 4 This is a side view of the tensioner in this embodiment.

[0017] Figure 5 This is an explanatory diagram of the assembly operation of the tensioner in this embodiment.

[0018] Figure 6 This is an explanatory diagram of the assembly operation of the tensioner in this embodiment.

[0019] Symbol Explanation

[0020] 30: Swing arm

[0021] 40: Belt drive device

[0022] 41: Drive pulley

[0023] 42: Driven pulley

[0024] 43: Toothed belt

[0025] 44: Tensioner

[0026] 51: Tensioner base

[0027] 54: Limit bolt

[0028] 55: Elongated hole

[0029] 58: Locking pin

[0030] 61: Tensioner arm

[0031] 62: Swing pin (swing shaft)

[0032] 63: Rotating pin (rotating shaft)

[0033] 65: Abutment protrusion (part of the tensioner arm)

[0034] 66: Tensioner roller

[0035] 67: Tensioner spring. Detailed Implementation

[0036] In one aspect of the belt drive device of the present invention, a belt is wound around a drive pulley and a driven pulley, and tension is applied to the belt by a tensioner. The tensioner has: a tensioner base disposed on the side of the belt in the axial direction of rotation of the belt; a tensioner arm swayably supported on the tensioner base; a tensioner roller rotatably supported on the tensioner arm; and a tensioner spring elastically connected to the tensioner arm. In the pressing direction where the tensioner roller presses against the belt, the elastic force of the tensioner spring is applied to the tensioner arm. When viewed from the side, the tensioner roller is located on the outside of the belt, and the tensioner spring is located on the inside of the belt. Thus, the above-mentioned problem is solved.

[0037] In one aspect of the belt drive device of the present invention, a belt is wound around a drive pulley and a driven pulley, and tension is applied to the belt by a tensioner. A tensioner base is disposed on the side of the belt, and a tensioner arm is oscillatingly supported on the tensioner base. A tensioner roller is rotatably supported on the tensioner arm, and a tensioner spring is elastically connected to the tensioner arm. In the direction in which the tensioner roller presses against the belt, the elastic force of the tensioner spring is applied to the tensioner arm, causing the tensioner arm to oscillate and the tensioner roller supported on the tensioner arm to press against the belt. Since the belt tension is automatically adjusted, belt adjustment work is unnecessary, improving assembly efficiency, and even if the belt extends its entire length, periodic re-tensioning is not required, improving maintainability. Furthermore, by maintaining the belt at an appropriate tension, belt fatigue can be reduced, extending its lifespan. Additionally, when viewed from the side, the tensioner roller is located on the outer side of the belt, and the tensioner spring is located on the inner side of the belt. By separately arranging tensioner rollers and tensioner springs inside and outside the belt, even with an automatic tensioner, the large size of the belt drive can be prevented.

[0038] [Example]

[0039] The straddle-type vehicle of this embodiment will now be described with reference to the accompanying drawings. Figure 1 This is a left-side view of the straddle-type vehicle in this embodiment. Additionally, in the following figures, arrow Fr indicates the front of the vehicle, arrow Re indicates the rear of the vehicle, arrow L indicates the left side of the vehicle, and arrow R indicates the right side of the vehicle.

[0040] like Figure 1 As shown, the straddle-type vehicle 1 is configured such that various covers, serving as exterior bodywork, are mounted on a curved beam frame 10. A head tube 11 is located at the front end of the frame 10, and a front frame 12 extends rearward and downward from the head tube 11. A pair of side frames 13 extend rearward from the lower part of the front frame 12, with the rear half of the pair of side frames 13 rising rearward and upward. A front fork 14 is steerably supported on the head tube 11, and a front wheel 15 is rotatably supported on the lower end of the front fork 14.

[0041] A mounting bracket 21 extends upward from near the front of a pair of side frames 13, and a mounting bracket 22 extends downward from the middle of the pair of side frames 13. A battery 23, rectangular in shape when viewed from the side, is fixed to the front and rear mounting brackets 21 and 22. The lower front corner of the battery 23 is fixed to the front mounting bracket 21, and the lower rear corner of the battery 23 is fixed to the rear mounting bracket 22. Thus, by fixing the lower rear corner at a position higher than the lower front corner of the battery 23, the battery 23 is supported from below in a forward-leaning posture on the pair of side frames 13.

[0042] A fixed bracket 24 extends downward from near the front of a pair of side frames 13, and a swing arm 30 is pivotally supported on the fixed bracket 24 via a pivot 25. The base of the swing arm 30 is a motor housing, and a motor 26 is disposed inside the motor housing (see reference). Figure 3 The rear wheel 27 is supported at the rear end of the swing arm 30 and connected to the rear suspension 28. By positioning the motor 26 near the pivot 25 of the swing arm 30, vibrations transmitted to the motor 26 when the swing arm 30 swings can be suppressed.

[0043] However, a belt drive that transmits power from the electric motor to the rear wheel is housed inside the swing arm. This belt drive requires manual adjustment of the belt tension. Adjusting the belt requires skill, and its power transmission function is prone to deviation. As the belt continues to be used, it extends its entire length, reducing tension and decreasing power transmission efficiency. Furthermore, the belt drive needs further miniaturization, necessitating a compact design within the limited space of the swing arm.

[0044] Therefore, the belt drive device 40 of this embodiment (refer to) Figure 2 An automatic tensioner structure is adopted, which applies tension to the belt using the reaction force of a spring. By automatically adjusting the belt tension using a spring, the belt adjustment work can be eliminated, and the assemblability of the belt drive 40 is improved. By keeping the belt constantly tensioned, tension reduction is suppressed even when the belt extends its entire length. In addition, the belt drive 40 is compactly arranged inside the swing arm 30, utilizing not only the space outside the annular belt on the inner side of the swing arm 30 but also the space inside the belt.

[0045] Reference Figure 2 and Figure 3 The belt drive device is described. Figure 2 This is a side view of the swing arm in this embodiment. Figure 3 It is cut along line AA Figure 2 A cross-sectional view of the swing arm. Additionally, Figure 2 This indicates the state of the swing arm cover being removed.

[0046] like Figure 2 and Figure 3 As shown, the swing arm 30 is constructed by mounting a swing arm cover 32 on the swing arm housing 31. The swing arm housing 31 has a left-right split structure, and a motor 26 is housed inside the swing arm housing 31. The left housing half 33 of the swing arm housing 31 extends rearward more than the right housing half 34, and a rear wheel support 35 is provided at the rear end of the left housing half 33. The drive shaft 36 and axle 37, which constitute a gear transmission, are rotatably supported on the rear end of the left housing half 33 and the rear wheel support 35, and the rear wheel 27 is fixedly supported on the axle 37.

[0047] A swing arm cover 32 is mounted on the left side of the opening of the left side housing half 33. A belt drive 40 is housed inside the left side housing half 33 and the swing arm cover 32. This belt drive 40 has an annular toothed belt 43 rotatably wound around a drive pulley 41 and a driven pulley 42, and tension is applied to the toothed belt 43 by a tensioner 44. The drive pulley 41 is fixed to the output shaft 29 of the motor 26 at the front of the swing arm 30, and the driven pulley 42 is fixed to the drive shaft 36 at the rear of the swing arm 30. Pulley teeth are formed on the outer circumferential surfaces of the drive pulley 41 and the driven pulley 42 to mesh with the toothed belt 43.

[0048] Thus, in the straddle-type vehicle 1, to ensure NV (Noise and Vibration) performance, driving performance, and maintenance-free operation suitable for electric vehicles, a structure combining belt drive and gear drive is adopted. Torque is transmitted from the output shaft 29 of the electric motor 26 through the drive pulley 41, toothed belt 43, and driven pulley 42 while being reduced in speed. Torque is further transmitted from the driven pulley 42 to the rear wheel 27 through the drive shaft 36 and axle 37 while being reduced in speed. In this case, to avoid poor power transmission due to skipped teeth, the tension of the toothed belt 43 is appropriately adjusted by the tensioner 44.

[0049] Tensioner 44 is disposed on the inner side of swing arm 30. The tensioner base 51 of tensioner 44, viewed from the side, is triangular in shape. Each vertex of the tensioner base 51 is fixed to three bosses 38a-38c protruding to the left from the left side housing half 33. Viewed from the side, boss 38a is located outside and above the toothed belt 43, while bosses 38b and 38c are located inside the toothed belt 43 and separated front and rear. Bosses 38a-38c protrude outward (to the left) in the vehicle width direction from the toothed belt 43. By fixing the tensioner base 51 to the top of the bosses 38a-38c, the tensioner base 51 is disposed to the side of the toothed belt 43. In other words, the tensioner base 51 is disposed axially to the side of the toothed belt 43 relative to its rotation.

[0050] Thus, the tensioner base 51 is positioned on the opposite side of the rear wheel 27 in the vehicle width direction relative to the toothed belt 43. In this case, the frame-like portion parallel to the side of the toothed belt 43 of the tensioner base 51 enters the inside of the swing arm cover 32. By utilizing the inside of the swing arm cover 32, the tensioner base 51 is provided without increasing the width dimension of the left side housing half 33 (swing arm 30). By positioning the tensioner base 51 on the opposite side of the rear wheel 27 by clamping the toothed belt 43, the clearance between the swing arm 30 and the rear wheel 27 is ensured, and the overall vehicle layout becomes easier.

[0051] Tensioner arm 61 is pivotally supported on an inclined frame at the front of tensioner base 51. The tensioner arm 61 is generally V-shaped when viewed from the side, with its bent portion supported by a pivot pin (pivot shaft) 62 on the inside (right side) of the tensioner base 51 in the machine width direction. One end of the tensioner arm 61 extends rearward relative to the pivot pin 62, and a tensioner roller 66 is rotatably supported on this end. The other end of the tensioner arm 61 extends downward relative to the pivot pin 62, and a tensioner spring 67 is elastically connected to this other end.

[0052] The tensioner roller 66 is supported by a rotating pin 63 on the inside (right side) of the tensioner arm 61 in the machine width direction, and the roller surface of the tensioner roller 66 contacts the outer peripheral surface of the toothed belt 43 from above. The tensioner spring 67 is supported by a retaining protrusion 64 (see reference). Figure 5 The tensioner arm 61 is held in place, and the other end of the tensioner arm 61 is pressed forward by the tensioner spring 67. In this way, the tensioner spring 67 applies a spring force to the tensioner arm 61 in the direction in which the tensioner roller 66 presses against the toothed belt 43, that is, in the clockwise direction centered on the swing pin 62.

[0053] The tensioner roller 66 presses down on the toothed belt 43 from above, pressing the upper tension side of the toothed belt 43 downwards, increasing the tension of the toothed belt 43. The tension of the toothed belt 43 is automatically adjusted by the reaction force of the tensioner spring 67, eliminating the need for adjustment work or periodic re-tensioning of the toothed belt 43. The tensioner roller 66 is located radially outward relative to the toothed belt 43. The tensioner spring 47 is located radially inward relative to the toothed belt 43. Furthermore, viewed from the side, the tensioner roller 66 is located outside and above the toothed belt 43, while the tensioner spring 67 is located inside the toothed belt 43. By utilizing both the outer and inner sides of the toothed belt 43, the enlargement of the belt drive 40 can be prevented.

[0054] The support plate 52 extends upward from the inclined frame on the rear side of the tensioner base 51, and the upper end of the support plate 52 bends outward (to the left) in the machine width direction. A through-hole is machined into the upper end of the support plate 52, and a limit bolt 54 is installed through the threaded hole at the upper end of the support plate 52. Furthermore, the limit bolt 54 is fixed by a lock nut 53. The limit bolt 54 restricts the upward swing of the tensioner arm 61 and prevents the tensioner roller 66 from bouncing off the toothed belt 43. In addition, by adjusting the insertion amount of the limit bolt 54 relative to the upper end of the support plate 52, the height of the top of the limit bolt 54 changes, thereby adjusting the swing amount of the tensioner arm 61.

[0055] An elongated hole 55 is formed longitudinally in the support plate 52, and an abutment protrusion 65 located at the top of the tensioner arm 61 enters the elongated hole 55. During the assembly of the tensioner 44 or the swing arm 30, excessive swinging of the tensioner arm 61 is limited, preventing the tensioner spring 67 from dislodging due to excessive swinging of the tensioner arm 61. For example, the tensioner spring 67 enters the retaining protrusion 64 of the tensioner arm 61, but by limiting excessive swinging of the tensioner arm 61, the tensioner spring 67 is prevented from dislodging from the retaining protrusion 64.

[0056] Viewed from the side, the top of the limiting bolt 54 overlaps with the elongated hole 55 of the tensioner base 51, and the limiting bolt 54 is located above the abutment protrusion 65 of the tensioner arm 61. The extending direction of the limiting bolt 54 is consistent with the extending direction of the elongated hole 55, and the limiting bolt 54 and the elongated hole 55 are located in the space behind the rotating pin 63 of the tensioner roller 66. Thus, the structure that prevents the tensioner roller 66 from springing up using the limiting bolt 54 and the structure that prevents the tensioner spring 67 from falling off using the elongated hole 55 are compactly combined, thereby suppressing the enlargement of the tensioner 44.

[0057] Viewed from the side, the swing pin 62 of the tensioner arm 61 is located radially outward of the rotation of the toothed belt 43, at the same height as the rotating pin 63 of the tensioner roller 66. The arm portion from the swing pin 62 to one end of the rotating pin 63 of the tensioner arm 61 extends in the front-rear direction, causing the tensioner spring 67 to face in the front-rear direction, thereby ensuring the spring length. Furthermore, since the tensioner arm 61 is formed to be relatively long in the front-rear direction, the height dimension of the tensioner arm 61 is also suppressed. Additionally, the fact that the swing pin 62 and the rotating pin 63 are at the same height does not necessarily mean that the two pins are exactly the same height; it may include an error to the extent that the two pins are considered to be at approximately the same height.

[0058] The retaining plate 56 protrudes rearward from near the rear corner of the tensioner base 51, and its rear end bends inward (to the right) in the vehicle width direction. A spring guide 68 is inserted into the rear end of the retaining plate 56, extending toward the other end of the tensioner arm 61. The other end of the tensioner arm 61 bends inward (to the right) in the vehicle width direction (see reference). Figure 5 The aforementioned retaining protrusion 64 is installed at the other end of the tensioner arm 61. The tensioner spring 67 is held in place by the spring guide 68 and the retaining protrusion 64 entering the inside of the tensioner spring 67.

[0059] The tensioner spring 67 extends parallel to the slack side of the toothed belt 43, which returns from the driven pulley 42 to the drive pulley 41. This allows the tensioner spring 67 to be positioned close to the slack side of the belt. Because it bends downwards from the tension side of the belt above the drive pulley 41 toward the driven pulley 42, interference between the tensioner spring 67 and the toothed belt 43 is suppressed even if the gap between the tension side of the belt above and the slack side of the belt below narrows. This ensures the spring length of the tensioner spring 67 without increasing the size of the tensioner 44.

[0060] Additionally, a small hole 57 is formed in the lower frame of the tensioner base 51, which overlaps with the tensioner arm 61 when viewed from the side. A locking pin 58 can be installed or removed through the small hole 57 in the tensioner base 51 (see reference). Figure 6 When the locking pin 58 is inserted into the small hole 57 of the tensioner base 51, the top end of the locking pin 58 protrudes inward from the width direction of the tensioner base 51. During the assembly of the tensioner 44, with the tensioner roller 66 floating from the toothed belt 43, the swing of the tensioner arm 61 is locked by the locking pin 58, thereby improving assemblability. Furthermore, the locking state of the tensioner arm 61 based on the locking pin 58 will be described later.

[0061] Reference Figures 4 to 6 The operation and assembly of the tensioner are explained. Figure 4 This is a side view of the tensioner in this embodiment. Figure 5 and Figure 6This is an explanatory diagram of the assembly operation of the tensioner in this embodiment.

[0062] like Figure 4 As shown, in the tensioner 44, the tensioner spring 67 is held in a contracted state between the retaining plate 56 on the rear side of the tensioner base 51 and the other end of the tensioner arm 61. The elastic force of the tensioner spring 67 presses the other end of the tensioner arm 61 forward. The elastic force of the tensioner spring 67 is converted into a rotational force of clockwise rotation with the swing pin 62 as the fulcrum, and the tensioner roller 66 on one end of the tensioner arm 61 is pressed against the outer circumferential surface of the toothed belt 43. The tension of the toothed belt 43 is automatically adjusted by the elastic force of the tensioner spring 67.

[0063] Power is transmitted from the drive pulley 41 to the driven pulley 42 via the toothed belt 43. Power is transmitted using the difference between the tension on the upper part of the belt from the drive pulley 41 toward the driven pulley 42 and the tension on the lower part of the belt returning from the driven pulley 42 to the drive pulley 41. Because of the automatic tensioner, no tension adjustment is required during the assembly of the tensioner 44, and even as the toothed belt 43 extends its full length over time, no readjustment is needed. Furthermore, by providing a tensioner spring 67 inside the toothed belt 43, the excessive size of the tensioner 44 can be prevented.

[0064] As described above, a limiting bolt 54 is installed on the tensioner base 51, and an abutment protrusion 65 is provided at one end of the tensioner arm 61. Even if excessive driving force changes are transmitted from the drive pulley 41 or driven pulley 42 to the toothed belt 43, the abutment protrusion 65 abuts against the limiting bolt 54, thus limiting the upward swing of the tensioner arm 61. The tensioner roller 66 will not bounce upward, and tooth skipping will not occur due to excessive driving force changes suppressing loosening of the lower part of the belt. In this case, the top of the limiting bolt 54 is adjusted to a height that will not cause tooth skipping due to the bounce of the tensioner roller 66.

[0065] like Figure 5 As shown, a spring guide 68 is detachably mounted on the retaining plate 56 of the tensioner base 51. During installation of the tensioner spring 67, by pulling the spring guide 68 out of the retaining plate 56, the tensioner spring 67 is prevented from over-contracting, and the retaining protrusion 64 of the tensioner arm 61 is inserted into the tensioner spring 67. Furthermore, after the tensioner spring 67 is installed, the spring guide 68 extends into the inner side of the tensioner spring 67 to prevent bending and apply appropriate elastic force to the tensioner arm 61.

[0066] Furthermore, during the assembly of the tensioner 44, the abutment protrusion 65 of the tensioner arm 61 enters the elongated hole 55 of the tensioner base 51. When the tensioner spring 67 is installed, the elastic force of the tensioner spring 67 acts on the tensioner arm 61, but the abutment protrusion 65 of the tensioner arm 61 abuts against the lower end of the elongated hole 55, thus restricting the downward swing of the tensioner arm 61. Since the forward swing of the other end of the tensioner arm 61 is also restricted, the tensioner spring 67 will not disengage from the retaining protrusion 64 of the tensioner arm 61, preventing the tensioner arm 61 from falling off.

[0067] like Figure 6 As shown, when the tensioner 44 is assembled to the swing arm 30, the tensioner spring 67 contracts, and the locking pin 58 is inserted into the small hole 57 of the tensioner base 51. When the tensioner arm 61 swings in the direction that the tensioner roller 66 is away from the toothed belt 43, the tensioner arm 61 abuts against the locking pin 58 and locks the swing. With the tensioner roller 66 separated from the toothed belt 43, the tensioner 44 can be easily assembled to the swing arm 30. After the tensioner 44 is assembled, by pulling out the locking pin 58, the tensioner roller 66 is pressed against the toothed belt 43, thereby applying tension.

[0068] As described above, in the belt drive device 40 according to this embodiment, since the tension of the toothed belt 43 is automatically adjusted, there is no need for adjustment work on the toothed belt 43, improving assemblability. Furthermore, even if the toothed belt 43 extends its entire length, it does not require periodic re-tensioning, improving maintainability. In addition, by maintaining the toothed belt 43 at an appropriate tension, fatigue of the toothed belt 43 can be reduced, extending its lifespan. Even with such an automatic tensioner, the tensioner roller 66 and the tensioner spring 67 can be separately disposed inside and outside the toothed belt 43, thereby preventing the belt drive device 40 from becoming too large.

[0069] In this embodiment, the tensioner spring is connected to the other end of the tensioner arm, but it is sufficient that the tensioner spring is connected to the tensioner arm so that the tensioner roller presses against the toothed belt. For example, the tensioner spring can be connected to one end of the tensioner arm, and the tensioner roller presses against the toothed belt by the elastic force of the tensioner spring.

[0070] In addition, in this embodiment, a toothed belt is used as an example, but the belt can also be composed of V-belt, flat belt, rib belt, etc.

[0071] In this embodiment, the tensioner base is formed into a triangular frame shape when viewed from the side, but the shape is not particularly limited as long as the tensioner base is located on the side of the belt. Furthermore, the tensioner base is not limited to the outer side of the belt in the width direction; it can also be located on the inner side of the belt in the width direction.

[0072] In addition, in this embodiment, the tensioner arm is formed in a side-view V-shape, but there is no particular limitation on the shape as long as the tensioner arm can be oscillatingly supported on the tensioner base.

[0073] In this embodiment, the tensioner spring extends parallel to the belt returning from the driven pulley to the drive pulley, but parallelism is not limited to complete parallelism. As long as it can be considered to be parallel to the belt returning from the driven pulley to the drive pulley, the tensioner spring can be approximately parallel to the belt returning from the driven pulley to the drive pulley.

[0074] Furthermore, the belt drive device in this embodiment is not limited to the straddle-type vehicle described above, but can also be used in other types of straddle-type vehicles. In addition, straddle-type vehicles are not limited to all vehicles in which the driver rides in a straddle position, but also include pedal-operated vehicles in which the driver does not ride in a straddle position.

[0075] As described above, the first embodiment is a belt drive 40 in which a belt (toothed belt 43) is wound around a drive pulley 41 and a driven pulley 42. Tension is applied to the belt by a tensioner 44. The tensioner has: a tensioner base 51 disposed on the side of the belt; a tensioner arm 61 oscillatingly supported on the tensioner base; a tensioner roller 66 rotatably supported on the tensioner arm; and a tensioner spring 67 elastically connected to the tensioner arm. In the direction in which the tensioner roller presses against the belt, the elastic force of the tensioner spring is applied to the tensioner arm. When configured from the side, the tensioner roller is located on the outside of the belt, and the tensioner spring is located on the inside of the belt. According to this structure, the tensioner arm oscillates due to the elastic force of the tensioner spring, and the tensioner roller supported on the tensioner arm presses against the belt. Since the belt tension is automatically adjusted, belt adjustment work is not required, improving assemblability. Furthermore, even if the belt extends its entire length, periodic re-tensioning is not required, improving maintainability. Furthermore, by maintaining the belt at appropriate tension, belt fatigue can be reduced and its lifespan extended. Even with such an automatic tensioner, the tensioner roller and tensioner spring can be set separately inside and outside the belt, thereby preventing the belt drive from becoming too large.

[0076] The second method, as in the first method, involves the swing axis (swing pin 62) of the tensioner arm, when viewed from the side, being at the same height as the rotation axis (rotation pin 63) of the tensioner roller on the outside of the belt. With this structure, the tensioner arm extends in the front-rear direction, aligning the tensioner spring in that direction, thus ensuring the spring length. Additionally, the height dimension of the tensioner arm can be controlled.

[0077] The third approach, as in the first or second approach, involves the tensioner spring extending parallel to the belt returning from the driven pulley to the driving pulley. This configuration ensures the appropriate spring length for the tensioner without increasing its size.

[0078] The fourth approach, in any of the first to third approaches, involves a belt drive housed within a swing arm 30 supporting the rear wheel, with the tensioner base positioned on the opposite side of the rear wheel in the vehicle width direction relative to the belt. According to this structure, by positioning the tensioner base, which clamps the belt, on the opposite side of the rear wheel, ensuring clearance between the swing arm and the rear wheel, the overall vehicle layout becomes easier.

[0079] The fifth method involves, in any of the first to fourth methods, the tensioner roller being positioned above the belt when viewed from the side, and a limiting bolt 54 being provided on the tensioner base to restrict the upward swing of the tensioner arm. According to this structure, the upward swing of the tensioner arm is restricted, preventing the tensioner roller from bouncing off the belt. Furthermore, by using the limiting bolt, the amount of swing of the tensioner arm can be adjusted.

[0080] The sixth method is, in the fifth method, to form an elongated hole 55 in the tensioner base for a portion of the tensioner arm (abutment protrusion 65) to enter. According to this structure, excessive swinging of the tensioner arm is limited during tensioner assembly, etc., and the tensioner spring can be prevented from falling off due to the swinging of the tensioner arm.

[0081] The seventh method is that, in the sixth method, when viewed from the side, the top of the limiting bolt overlaps with the elongated hole, and the limiting bolt is located above a portion of the tensioner arm. According to this structure, the structure that uses the limiting bolt to prevent the tensioner roller from bouncing and the structure that uses the elongated hole to prevent the tensioner spring from falling off can be compactly combined, thereby suppressing the enlargement of the tensioner.

[0082] The eighth embodiment, in any of the first to seventh embodiments, involves a locking pin 58 that is detachable from the tensioner base. This locking pin locks the swing of the tensioner arm, preventing it from swinging in the direction in which the tensioner roller is disengaged from the belt. According to this configuration, by installing the locking pin on the tensioner base, the tensioner can be easily assembled to the swing arm with the tensioner roller disengaged from the belt.

[0083] In addition, this embodiment has been described, but as other embodiments, the above embodiments and variations may be combined in whole or in part.

[0084] Furthermore, the technology of the present invention is not limited to the above embodiments, and various changes, substitutions, and modifications can be made without departing from the spirit of the technical concept. In addition, if the technical concept can be implemented in another way through technological advancements or derived technologies, this method can be used for implementation. Therefore, the scope of protection claimed covers all embodiments that can be included within the scope of the technical concept.

Claims

1. A belt drive device, characterized in that, have: A belt configured to rotate wound around a drive pulley and a driven pulley; and A tensioner configured to apply tension to the belt. The tensioner has: Tensioner base, which is disposed on the side of the belt in the axial direction of the belt's rotation; Tensioner arm, which is oscillatingly supported on the tensioner base; Tensioner roller, which is rotatably supported on the tensioner arm; as well as The tensioner spring is elastically connected to the tensioner arm. The tensioner spring is configured such that, in the direction in which the tensioner roller presses against the belt, the tensioner spring's elastic force applies to the tensioner arm. The tensioner roller is located radially outside the belt relative to the belt's rotation, and the tensioner spring is located radially inside the belt relative to the belt.

2. The belt drive device as described in claim 1, characterized in that, When the belt drive is mounted on the vehicle, When viewed from the side of the vehicle, the swing axis of the tensioner arm is located at the same height as the rotation axis of the tensioner roller relative to the belt on the radially outer side.

3. The belt drive device as described in claim 1 or 2, characterized in that, The tensioner spring extends parallel to a portion of the belt returning from the driven pulley to the drive pulley.

4. The belt drive device as described in claim 1 or 2, characterized in that, When the belt drive is mounted on the vehicle, The belt drive is housed in the swing arm that supports the rear wheel of the vehicle. The tensioner base is located on the side opposite to the rear wheel in the vehicle width direction relative to the belt.

5. The belt drive device as described in claim 1 or 2, characterized in that, When the belt drive is mounted on the vehicle, When viewed from the side of the vehicle, the tensioner roller is positioned above the belt. The tensioner base is provided with a limiting bolt to restrict the tensioner arm from swinging upward.

6. The belt drive device as described in claim 5, characterized in that, An elongated hole is formed in the tensioner base for a portion of the tensioner arm to enter.

7. The belt drive device as described in claim 6, characterized in that, When viewed from the side, the top of the limiting bolt overlaps with the elongated hole, and the limiting bolt is located above a portion of the tensioner arm.

8. The belt drive device as described in claim 1 or 2, characterized in that, A locking pin is detachable from the tensioner base and locks the swing of the tensioner arm. When the locking pin is installed on the tensioner base, the locking pin locks the swing of the tensioner arm in a state where the tensioner arm swings in the direction in which the tensioner roller moves away from the belt.

9. The belt drive device as described in claim 1 or 2, characterized in that, It also has a spring guide that is inserted into a retaining piece disposed at one end of the tensioner base. A retaining protrusion is provided at one end of the tensioner arm. The spring guide and the retaining protrusion enter the inside of the tensioner spring, and the tensioner spring is held by the spring guide and the retaining protrusion.

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