Belt transmission

Abstract

The belt tension can be easily adjusted, and the belt drive system can be installed compactly. [Solution] In the belt drive device (40), a belt (43) is wrapped around a drive pulley (41) and a driven pulley (42), and tension is applied to the belt by a tensioner (44). The tensioner is provided with a tensioner base (51) installed on the side of the belt, a tensioner arm (61) pivotably 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 spring force of the tensioner spring is applied to the tensioner arm in the direction in which the tensioner roller presses against the belt. In a side view, the tensioner roller is located on the outside of the belt, and the tensioner spring is located on the inside of the belt.

Description

【Technical Field】 【0001】 The present invention relates to a belt transmission device. 【Background Art】 【0002】 Conventionally, as a belt transmission device, one that transmits power from an output shaft connected to a drive source to a drive wheel via a belt is known (for example, see Patent Document 1). In the belt transmission device described in Patent Document 1, a drive pulley is fixed to the output shaft, a driven pulley is fixed to the drive wheel, and a belt is wound around the drive pulley and the driven pulley. Power is transmitted by the difference between the tension that pulls the belt by the driven pulley and the tension of the belt that returns to the drive pulley. Further, rollers are installed around the drive pulley, and the rollers prevent the belt from lifting. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Patent No. 4197067 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 By the way, in a belt transmission device, the tension of the belt is adjusted by changing the distance between the pulleys, an idler roller, a tensioner, etc. In the case of changing the distance between the pulleys or an idler roller, since the length of the belt changes depending on the usage situation, regular tension confirmation and adjustment work are required, and measuring instruments and maintenance skills are required. When adjusting the length of the belt by a tensioner, a large space must be secured. 【0005】 The present invention has been made in view of such points, and an object thereof is to provide a belt transmission device that can easily adjust the tension of the belt and can be installed compactly. 【Means for Solving the Problems】 【0006】 A belt drive device according to one aspect of the present invention is a belt drive device in which a belt is wrapped around a drive pulley and a driven pulley, and tension is applied to the belt by a tensioner, wherein the tensioner comprises a tensioner base installed on the side of the belt, a tensioner arm pivotably supported on the tensioner base, a tensioner roller rotatably supported on the tensioner arm, and a tensioner spring elastically connected to the tensioner arm, wherein the spring force of the tensioner spring is applied to the tensioner arm in the direction in which the tensioner roller presses against the belt, and in a side view, the tensioner roller is located on the outside of the belt and the tensioner spring is located on the inside of the belt, thereby solving the above problem. [Effects of the Invention] 【0007】 According to one embodiment of the present invention, the tensioner arm swings due to the spring force of the tensioner spring, and the tensioner roller supported by the tensioner arm is pressed against the belt. Since the belt tension is automatically adjusted, belt adjustment work is unnecessary, improving ease of assembly, and maintenance is improved as periodic re-tensioning is unnecessary even if the belt length is extended. In addition, by maintaining the belt at the appropriate tension, belt fatigue is reduced and the lifespan can be extended. Even when such an auto-tensioner is adopted, the tensioner roller and tensioner spring are installed separately on the inside and outside of the belt, so the size of the belt transmission device can be kept down. [Brief explanation of the drawing] 【0008】 [Figure 1] This is a left side view of the saddle-type vehicle of this embodiment. [Figure 2] This is a side view of the swing arm in this embodiment. [Figure 3] Figure 2 is a cross-sectional view of the swing arm cut along line AA. [Figure 4]This is a side view of the tensioner in this embodiment. [Figure 5] This is an explanatory diagram of the assembly procedure for the tensioner in this embodiment. [Figure 6] This is an explanatory diagram of the assembly procedure for the tensioner in this embodiment. [Modes for carrying out the invention] 【0009】 In one embodiment of the present invention, a belt is wrapped around a drive pulley and a driven pulley, and tension is applied to the belt by a tensioner. The tensioner base of the tensioner is installed on the side of the belt, and a tensioner arm is pivotably 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. The spring force of the tensioner spring is applied to the tensioner arm in the direction in which the tensioner roller presses against the belt, causing the tensioner arm to pivot 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 ease of assembly, and maintenance is improved as periodic re-tensioning is unnecessary even if the belt length increases. In addition, by maintaining the belt at the appropriate tension, belt fatigue is reduced and the lifespan can be extended. Furthermore, in a side view, the tensioner roller is located on the outside of the belt, while the tensioner spring is located on the inside. By separating the tensioner roller and tensioner spring on the inside and outside of the belt, it is possible to keep the size of the belt drive system down even when an automatic tensioner is used. [Examples] 【0010】 The saddle-type vehicle of this embodiment will be described below with reference to the attached drawings. Figure 1 is a left side view of the saddle-type vehicle of this embodiment. 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. 【0011】 As shown in Figure 1, the saddle-type vehicle 1 is constructed by attaching various covers as the exterior of the vehicle body to an underbone-type body frame 10. A head pipe 11 is provided at the front end of the body frame 10, and a front frame 12 extends diagonally downward and rearward from the head pipe 11. A pair of side frames 13 extend from the lower part of the front frame 12 toward the rear, and the rear half of the pair of side frames 13 rises diagonally upward and rearward. A front fork 14 is supported on the head pipe 11 so as to be steerable, and a front wheel 15 is rotatably supported at the lower end of the front fork 14. 【0012】 A fixing bracket 21 extends upward from near the front rise of a pair of side frames 13, and a fixing bracket 22 extends downward from the middle of the pair of side frames 13. A battery 23, which is rectangular in side view, is fixed to the front and rear fixing brackets 21 and 22. The lower front corner of the battery 23 is fixed to the front fixing bracket 21, and the lower rear corner of the battery 23 is fixed to the rear fixing bracket 22. In this way, the lower rear corner of the battery 23 is fixed at a higher position than the lower front corner, so that the battery 23 is supported from below in a forward-tilting position by the pair of side frames 13. 【0013】 A fixing bracket 24 extends downward from near the front rise of a pair of side frames 13, and a swingarm 30 is pivotably supported on the fixing bracket 24 via a pivot 25. The base end of the swingarm 30 is a motor case, and a motor 26 (see Figure 3) is installed inside the motor case. The rear end of the swingarm 30 supports the rear wheel 27 and is connected to the rear suspension 28. By positioning the motor 26 closer to the pivot 25 of the swingarm 30, vibrations transmitted to the motor 26 when the swingarm 30 swings are suppressed. 【0014】 Incidentally, the inside of the swingarm houses a belt drive system that transmits power from the motor to the rear wheel. With such a belt drive system, the belt tension must be adjusted manually. Adjusting the belt requires skill, and variations in the belt's power transmission function are likely to occur. As the belt continues to be used, its overall length increases, the tension decreases, and the power transmission function deteriorates. Furthermore, there is a demand for further miniaturization of the belt drive system, and it must be compactly installed in the limited mounting space of the swingarm. 【0015】 Therefore, the belt drive device 40 of this embodiment (see Figure 2) employs an auto-tensioner structure that applies tension to the belt using the reaction force of a spring. By automatically adjusting the belt tension with a spring, the assembly of the belt drive device 40 is improved while eliminating the need for belt adjustment work. Because the belt is always taut, the decrease in tension is suppressed even when the total length of the belt is extended. Furthermore, by utilizing not only the space outside the annular belt inside the swing arm 30 but also the space inside the belt, the belt drive device 40 is compactly installed inside the swing arm 30. 【0016】 The belt transmission device will be described with reference to Figures 2 and 3. Figure 2 is a side view of the swing arm of this embodiment. Figure 3 is a cross-sectional view of the swing arm of Figure 2, taken along line AA. Note that Figure 2 shows the swing arm with the cover removed. 【0017】 As shown in FIGS. 2 and 3, the swing arm 30 is configured by attaching a swing arm cover 32 to a swing arm case 31. The swing arm case 31 has a left - right split structure, and a motor 26 is housed inside the swing arm case 31. The left - hand case half 33 of the swing arm case 31 extends rearward from the right - hand case half 34, and a rear - wheel support portion 35 is provided at the rear end portion of the left - hand case half 33. A drive shaft 36 and an axle shaft 37 that constitute a gear transmission are rotatably supported at the rear end portion of the left - hand case half 33 and the rear - wheel support portion 35, and a rear wheel 27 is fixedly supported on the axle shaft 37. 【0018】 The swing arm cover 32 is attached to the open left - hand side surface of the left - hand case half 33. Inside the left - hand case half 33 and the swing arm cover 32, an annular toothed belt (belt) 43 is wound around a drive pulley 41 and a driven pulley 42, and a belt transmission device 40 to which tension is applied to the toothed belt 43 by a tensioner 44 is housed. The drive pulley 41 is fixed to the output shaft 29 of the motor 26 on the front side of the swing arm 30, and the driven pulley 42 is fixed to the drive shaft 36 on the rear side of the swing arm 30. Pulley teeth are formed on the outer peripheral surfaces of the drive pulley 41 and the driven pulley 42 so as to mesh with the toothed belt 43. 【0019】 Thus, in order to ensure NV (Noise and Vibration) performance, drivability, and maintenance - free characteristics suitable for an electric vehicle, a structure combining belt transmission and gear transmission is adopted in the saddle - riding type vehicle 1. Torque is transmitted from the output shaft 29 of the motor 26 through the drive pulley 41, the toothed belt 43, and the driven pulley 42 while being decelerated, and torque is transmitted to the rear wheel 27 from the driven pulley 42 through the drive shaft 36 and the axle shaft 37 while being further decelerated. In this case, in order to avoid power - transmission failure due to tooth skipping, the tension of the toothed belt 43 is appropriately adjusted by the tensioner 44. 【0020】 The tensioner 44 is installed inside the swing arm 30. The tensioner base 51 of the tensioner 44 is formed in a triangular frame shape in side view, and each vertex portion of the tensioner base 51 is fixed to three bosses 38a - 38c that protrude leftward from the left case half 33. In side view, the boss 38a is located outside and above the toothed belt 43, and the bosses 38b, 38c are located inside the toothed belt 43 and separated front and rear. The bosses 38a - 38c protrude outward (left side) in the vehicle width direction from the toothed belt 43, and the tensioner base 51 is fixed to the tips of the bosses 38a - 38c, so that the tensioner base 51 is installed on the side of the toothed belt 43. 【0021】 Thus, the tensioner base 51 is located on the opposite side in the vehicle width direction from the rear wheel 27 with respect to the toothed belt 43. In this case, a frame-shaped portion parallel to the side surface 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 installed without increasing the width dimension of the left case half 33 (swing arm 30). Since the tensioner base 51 is positioned on the opposite side of the rear wheel 27 across the toothed belt 43, a gap between the swing arm 30 and the rear wheel 27 is secured, facilitating the layout of the entire vehicle. 【0022】 A tensioner arm 61 is supported swingably on the inclined frame on the front side of the tensioner base 51. The tensioner arm 61 is formed in a substantially V shape in side view, and the bent portion of the tensioner arm 61 is supported on the inner side (right side) in the vehicle width direction of the tensioner base 51 via a swing pin (swing axis) 62. One end side of the tensioner arm 61 extends rearward from the swing pin 62, and a tensioner roller 66 is supported rotatably on one end side of the tensioner arm 61. The other end side of the tensioner arm 61 extends downward from the swing pin 62, and a tensioner spring 67 is elastically connected to the other end side of the tensioner arm 61. 【0023】 The tensioner roller 66 is supported on the inner side (right side) of the tensioner arm 61 in the vehicle width direction via a rotating pin 63, and the roller surface of the tensioner roller 66 is in contact with the outer circumferential surface of the toothed belt 43 from above. The tensioner spring 67 is held by the tensioner arm 61 via a retaining projection 64 (see Figure 5), and the other end of the tensioner arm 61 is pushed forward by the tensioner spring 67. In this way, the spring force of the tensioner spring 67 is applied to the tensioner arm 61 in the direction in which the tensioner roller 66 presses against the toothed belt 43, that is, in a clockwise direction around the pivoting pin 62. 【0024】 The tensioner roller 66 is pressed against the toothed belt 43 from above, pushing the tensioned upper side of the toothed belt 43 downwards and 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 manual adjustment or periodic re-tensioning of the toothed belt 43. In a side view, the tensioner roller 66 is located on the outside and above the toothed belt 43, while the tensioner spring 67 is located on the inside of the toothed belt 43. By installing the tensioner 44 using not only the outside but also the inside of the toothed belt 43, the size of the belt drive device 40 is kept down. 【0025】 A support piece 52 extends upward from the inclined frame at the rear of the tensioner base 51, and the upper end of the support piece 52 is bent outward (to the left) in the vehicle width direction. A through-hole is machined into the upper end of the support piece 52, and a limit bolt 54 is installed by passing through the screw hole in the upper end of the support piece 52. Furthermore, the limit bolt 54 is secured by a lock nut 53. The limit bolt 54 restricts the upward swing of the tensioner arm 61, preventing the tensioner roller 66 from bouncing up from the toothed belt 43. In addition, by adjusting the insertion amount of the limit bolt 54 into the upper end of the support piece 52, the height of the tip of the limit bolt 54 changes, and the amount of swing of the tensioner arm 61 is adjusted. 【0026】 The support piece 52 has a vertically oriented elongated hole 55, into which a contact projection 65 provided at the tip of the tensioner arm 61 fits. Excessive swinging of the tensioner arm 61 is restricted during assembly of the tensioner 44 and when it is attached to the swing arm 30, preventing the tensioner spring 67 from falling out due to excessive swinging of the tensioner arm 61. For example, the tensioner spring 67 fits into the retaining projection 64 of the tensioner arm 61, but the restriction of excessive swinging of the tensioner arm 61 prevents the tensioner spring 67 from coming loose from the retaining projection 64. 【0027】 In a side view, the tip of the limit bolt 54 overlaps with the elongated hole 55 of the tensioner base 51, and the limit bolt 54 is positioned above the contact projection 65 of the tensioner arm 61. The extending direction of the limit bolt 54 and the extending direction of the elongated hole 55 coincide, and the limit bolt 54 and the elongated hole 55 are positioned in the space behind the rotation pin 63 of the tensioner roller 66. As a result, the structure that prevents the tensioner roller 66 from bouncing up by the limit bolt 54 and the structure that prevents the tensioner spring 67 from falling out by the elongated hole 55 are compactly combined, and the size of the tensioner 44 is kept down. 【0028】 In a side view, the oscillating pin 62 of the tensioner arm 61 is located outside the toothed belt 43 and at the same height as the rotating pin 63 of the tensioner roller 66. The arm portion at one end of the tensioner arm 61, from the oscillating pin 62 to the rotating pin 63, extends in the front-rear direction, and the spring length is ensured by orienting the tensioner spring 67 in the front-rear direction. In addition, the height dimension of the tensioner arm 61 is also kept down by making the tensioner arm 61 long in the front-rear direction. Note that the oscillating pin 62 and the rotating pin 63 being at the same height does not mean that both pins are at exactly the same height; they may have an error that allows them to be considered to be at approximately the same height. 【0029】 A retaining piece 56 protrudes rearward from near the rear corner of the tensioner base 51, and the rear end of the retaining piece 56 is bent inward (to the right) in the vehicle width direction. A spring guide 68 is inserted into the rear end of the retaining piece 56, and the spring guide 68 extends toward the other end of the tensioner arm 61. The other end of the tensioner arm 61 is bent inward (to the right) in the vehicle width direction (see Figure 5), and the retaining projection 64 described above is attached to the other end of the tensioner arm 61. The tensioner spring 67 is held in place by the spring guide 68 and the retaining projection 64 fitting inside the tensioner spring 67. 【0030】 The tensioner spring 67 extends parallel to the toothed belt 43 that returns from the driven pulley 42 to the drive pulley 41, i.e., the slack side of the lower part of the belt. This allows the tensioner spring 67 to be positioned closer to the slack side of the lower part of the belt. Even if the tensioned upper part of the belt, which goes from the drive pulley 41 to the driven pulley 42, is bent downward, and the distance between the tensioned upper part of the belt and the slack lower part of the belt is narrowed, interference between the tensioner spring 67 and the toothed belt 43 is suppressed. The spring length of the tensioner spring 67 is ensured without increasing the size of the tensioner 44. 【0031】 Furthermore, a small hole 57 is formed in the lower frame of the tensioner base 51, and in a side view, the small hole 57 overlaps with the tensioner arm 61. A lock pin 58 (see Figure 6) can be attached to and detached from the small hole 57 of the tensioner base 51. When the lock pin 58 is inserted into the small hole 57 of the tensioner base 51, the tip of the lock pin 58 protrudes from the inside of the tensioner base 51 in the vehicle width direction. When assembling the tensioner 44, the swing of the tensioner arm 61 is locked by the lock pin 58 with the tensioner roller 66 lifted from the toothed belt 43, improving ease of assembly. The locked state of the tensioner arm 61 by the lock pin 58 will be described later. 【0032】 The operation and assembly of the tensioner will be explained with reference to Figures 4 to 6. Figure 4 is a side view of the tensioner of this embodiment. Figures 5 and 6 are explanatory diagrams of the assembly of the tensioner of this embodiment. 【0033】 As shown in Figure 4, in the tensioner 44, the tensioner spring 67 is held in a contracted state between the rear retaining piece 56 of the tensioner base 51 and the other end of the tensioner arm 61. The spring force of the tensioner spring 67 pushes the other end of the tensioner arm 61 forward. The spring force of the tensioner spring 67 is converted into a clockwise rotational force with the pivot pin 62 as the pivot point, and the tensioner roller 66 on one end of the tensioner arm 61 is pressed against the outer surface of the toothed belt 43. The tension of the toothed belt 43 is automatically adjusted by the spring force of the tensioner spring 67. 【0034】 Power is transmitted from the drive pulley 41 to the driven pulley 42 via the toothed belt 43. Power is transmitted by utilizing the difference between the tension on the upper side of the belt going from the drive pulley 41 to the driven pulley 42 and the tension on the lower side of the belt returning from the driven pulley 42 to the drive pulley 41. The auto tensioner eliminates the need to adjust the tension when assembling the tensioner 44, and also eliminates the need to readjust the tension even if the overall length of the toothed belt 43 increases over time. In addition, the tensioner spring 67 is installed inside the toothed belt 43, which helps to keep the tensioner 44 from becoming too large. 【0035】 As described above, a limit bolt 54 is attached to the tensioner base 51, and a contact projection 65 is provided at one end of the tensioner arm 61. Even if excessive driving force fluctuations are transmitted to the toothed belt 43 from the drive pulley 41 or driven pulley 42, the contact projection 65 abuts against the limit bolt 54, restricting the upward swing of the tensioner arm 61. The tensioner roller 66 is not flipped upward, and slack in the lower part of the belt due to excessive driving force fluctuations is suppressed, preventing tooth skipping. In this case, the tip of the limit bolt 54 is adjusted to a height that prevents tooth skipping due to the flipping of the tensioner roller 66. 【0036】 As shown in Figure 5, a spring guide 68 is detachably attached to the retaining piece 56 of the tensioner base 51. When installing the tensioner spring 67, the spring guide 68 is pulled out from the retaining piece 56, allowing the retaining projection 64 of the tensioner arm 61 to be inserted into the tensioner spring 67 without compressing the tensioner spring 67 more than necessary. Furthermore, after the tensioner spring 67 is installed, the spring guide 68 moves further into the back of the tensioner spring 67, preventing the tensioner spring 67 from bending and ensuring that the tensioner arm 61 is subjected to the appropriate spring force. 【0037】 Furthermore, during the assembly of the tensioner 44, the contact projection 65 of the tensioner arm 61 is inserted into the elongated hole 55 of the tensioner base 51. When the tensioner spring 67 is attached, the spring force of the tensioner spring 67 acts on the tensioner arm 61, but the contact projection 65 of the tensioner arm 61 abuts against the lower end of the elongated hole 55, restricting the downward swing of the tensioner arm 61. The forward swing of the other end of the tensioner arm 61 is also restricted, so the tensioner spring 67 does not come out of the retaining projection 64 of the tensioner arm 61, and the tensioner arm 61 does not fall off. 【0038】 As shown in Figure 6, when the tensioner 44 is assembled to the swing arm 30, the tensioner spring 67 is compressed and the lock pin 58 is inserted into the small hole 57 of the tensioner base 51. With the tensioner arm 61 swinging in the direction that separates the tensioner roller 66 from the toothed belt 43, the tensioner arm 61 abuts against the lock pin 58 and the swing is locked. The tensioner 44 can be easily assembled to the swing arm 30 while the tensioner roller 66 remains separated from the toothed belt 43. After the tensioner 44 is assembled, removing the lock pin 58 presses the tensioner roller 66 against the toothed belt 43, applying tension. 【0039】 As described above, with the belt drive device 40 of this embodiment, the tension of the toothed belt 43 is automatically adjusted, eliminating the need for manual adjustment of the toothed belt 43 and improving ease of assembly. Furthermore, even if the overall length of the toothed belt 43 increases, periodic re-tensioning is unnecessary, improving maintainability. In addition, by maintaining the toothed belt 43 at the appropriate tension, fatigue of the toothed belt 43 is reduced, extending its lifespan. Even with the adoption of such an auto-tensioner, the tensioner roller 66 and tensioner spring 67 are installed separately inside and outside the toothed belt 43, thus preventing an increase in the size of the belt drive device 40. 【0040】 In this embodiment, the tensioner spring is connected to the other end of the tensioner arm, but it is sufficient for the tensioner spring to be connected to the tensioner arm so that the tensioner roller presses against the toothed belt. For example, the tensioner spring may be connected to one end of the tensioner arm, and the tensioner roller may be pressed against the toothed belt by the spring force of the tensioner spring. 【0041】 Furthermore, although a toothed belt was used as an example in this embodiment, the belt may be a V-belt, flat belt, ribbed belt, or the like. 【0042】 Furthermore, in this embodiment, the tensioner base is formed in the shape of a triangular frame when viewed from the side, but the shape of the tensioner base is not particularly limited as long as it is installed on the side of the belt. Also, the tensioner base is not limited to being installed on the outside of the belt in the vehicle width direction, but may also be installed on the inside of the belt in the vehicle width direction. 【0043】 Furthermore, although the tensioner arm is formed in a V-shape when viewed from the side in this embodiment, the shape of the tensioner arm is not particularly limited as long as it is pivotably supported on the tensioner base. 【0044】 Furthermore, 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 perfect parallelism. It is sufficient for the tensioner spring to be approximately parallel to the belt returning from the driven pulley to the drive pulley, to the extent that the tensioner spring can be considered parallel to the belt returning from the driven pulley to the drive pulley. 【0045】 Furthermore, the belt transmission system of this embodiment may be used not only in the saddle-type vehicle described above, but also in other types of saddle-type vehicles. It should be noted that the term "saddle-type vehicle" is not limited to all vehicles in which the driver sits straddling a seat, but also includes scooter-type vehicles in which the driver does not straddle a seat. 【0046】 As described above, the first embodiment is a belt drive device (40) in which a belt (toothed belt 43) is wrapped around a drive pulley (41) and a driven pulley (42), and tension is applied to the belt by a tensioner (44). The tensioner comprises a tensioner base (51) installed on the side of the belt, a tensioner arm (61) pivotably 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 spring force of the tensioner spring is applied to the tensioner arm in the direction in which the tensioner roller presses against the belt. In a side view, the tensioner roller is located on the outside of the belt, and the tensioner spring is located on the inside of the belt. With this configuration, the tensioner arm pivots due to the spring force of the tensioner spring, and the tensioner roller supported on the tensioner arm presses against the belt. Because the belt tension is automatically adjusted, manual belt adjustment is unnecessary, improving ease of assembly. Furthermore, even if the belt length increases, periodic re-tensioning is no longer required, improving maintainability. Maintaining the belt at the appropriate tension also reduces belt fatigue and extends its lifespan. Even with the adoption of such an auto-tensioner, the tensioner roller and tensioner spring are installed separately on the inside and outside of the belt, preventing an increase in the overall size of the belt drive system. 【0047】 In the second embodiment, in a side view of the first embodiment, the pivot axis (pivot pin 62) of the tensioner arm is located outside the belt and at the same height as the rotation axis (rotation pin 63) of the tensioner roller. With this configuration, the tensioner arm extends in the front-rear direction, and the spring length can be ensured by orienting the tensioner spring in the front-rear direction. In addition, the height dimension of the tensioner arm can be reduced. 【0048】 In a third embodiment, the tensioner spring extends parallel to the belt returning from the driven pulley to the drive pulley, as in the first or second embodiment. This configuration allows for sufficient spring length of the tensioner spring without increasing the size of the tensioner. 【0049】 The fourth embodiment is one of the first to third embodiments in which the belt drive system is housed in a swing arm (30) that supports the rear wheel, and the tensioner base is located on the opposite side of the belt from the rear wheel in the vehicle width direction. With this configuration, by positioning the tensioner base on the opposite side of the belt from the rear wheel, a gap is secured between the swing arm and the rear wheel, making the overall layout of the vehicle easier. 【0050】 The fifth embodiment is one of the first to fourth embodiments, in which, in a side view, the tensioner roller is positioned above the belt, and the tensioner base is provided with a limit bolt (54) that restricts the upward swing of the tensioner arm. With this configuration, the upward swing of the tensioner arm is restricted, and the tensioner roller can be prevented from bouncing up from the belt. In addition, the amount of swing of the tensioner arm can be adjusted by restricting it with the limit bolt. 【0051】 The sixth aspect is a configuration of the fifth aspect in which the tensioner base has an elongated hole (55) into which a part of the tensioner arm (contact projection 65) fits. With this configuration, excessive swinging of the tensioner arm is restricted during assembly of the tensioner, and the tensioner spring can be prevented from falling off due to the swinging of the tensioner arm. 【0052】 The seventh aspect is a side view of the sixth aspect, in which the tip of the limit bolt overlaps the elongated hole, and the limit bolt is positioned above a part of the tensioner arm. With this configuration, the structure to prevent the tensioner roller from bouncing up using the limit bolt and the structure to prevent the tensioner spring from falling out using the elongated hole are compactly combined, and the size of the tensioner can be kept down. 【0053】 The eighth aspect is one of the first to seventh aspects, wherein a lock pin (58) that locks the swing of the tensioner arm is detachably attached to the tensioner base, and the lock pin locks the swing of the tensioner arm when the tensioner arm is swung in a direction that separates the tensioner roller from the belt. With this configuration, by attaching the lock pin to the tensioner base, the tensioner can be easily assembled to the swing arm while keeping the tensioner roller separated from the belt. 【0054】 Although this embodiment has been described, other embodiments may include combinations of the above embodiment and its modifications, either entirely or partially. 【0055】 Furthermore, the technology of the present invention is not limited to the embodiments described above, and may be modified, substituted, or transformed in various ways without departing from the spirit of the technical idea. Moreover, if the technical idea can be realized in a different way by advances in the technology or by other derived technologies, it may be implemented by that method. Accordingly, the claims cover all embodiments that may fall within the scope of the technical idea. [Explanation of Symbols] 【0056】 30: Swingarm 40: Belt transmission system 41: Drive Pulley 42: Driven pulley 43: Toothed belt (belt) 44: Tensioner 51: Tensioner Base 54: Limit Bolt 55: Slotted hole 58: Lock pin 61: Tensioner Arm 62: Oscillating pin (oscillating axis) 63: Rotating pin (rotating axis) 65: Contact projection (part of the tensioner arm) 66: Tensionorola 67: Tensioner Spring

Claims

[Claim 1] A belt drive device in which a belt is wrapped around a drive pulley and a driven pulley, and tension is applied to the belt by a tensioner, The tensioner mentioned above, A tensioner base is installed on the side of the aforementioned belt, A tensioner arm is pivotably supported on the tensioner base, A tensioner roller rotatably supported on the tensioner arm, The tensioner arm is elastically connected to a tensioner spring, The spring force of the tensioner spring is applied to the tensioner arm in the direction in which the tensioner roller presses against the belt. A belt transmission device characterized in that, in a side view, the tensioner roller is located on the outside of the belt and the tensioner spring is located on the inside of the belt. [Claim 2] The belt transmission device according to claim 1, characterized in that, in a side view, the pivot axis of the tensioner arm is located outside the belt and at the same height as the rotation axis of the tensioner roller. [Claim 3] The belt transmission device according to claim 1 or 2, characterized in that the tensioner spring extends parallel to the belt returning from the driven pulley to the drive pulley. [Claim 4] The aforementioned belt transmission device is housed in the swing arm that supports the rear wheel. The belt transmission device according to claim 1 or 2, characterized in that the tensioner base is located on the opposite side of the vehicle width direction from the rear wheel with respect to the belt. [Claim 5] In a side view, the tensioner roller is located above the belt. The belt transmission device according to claim 1 or 2, characterized in that the tensioner base is provided with a limit bolt that restricts the upward swinging of the tensioner arm. [Claim 6] The belt transmission device according to claim 5, characterized in that the tensioner base has an elongated hole into which a part of the tensioner arm fits. [Claim 7] The belt transmission device according to claim 6, characterized in that, in a side view, the tip of the limit bolt overlaps the elongated hole, and the limit bolt is located above a part of the tensioner arm. [Claim 8] A locking pin for locking the swing of the tensioner arm is detachably attached to the tensioner base. The belt transmission device according to claim 1 or 2, characterized in that the lock pin locks the swing of the tensioner arm while the tensioner arm is swung in a direction that separates the tensioner roller from the belt.

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