Optical fiber around guide wheel system

Abstract

The application provides a fiber winding guide wheel system, which comprises a guide wheel system base frame, a near fiber winding wheel set and a near fiber releasing wheel set arranged on the guide wheel system base frame, the near fiber winding wheel set comprises a pair of obliquely arranged guide wheels, the pair of guide wheels are provided with a gap for the fiber to pass through, the near fiber releasing wheel set comprises a longitudinal wide guide wheel, a plurality of guide pulleys are arranged between the pair of guide wheels and the longitudinal wide guide wheel, the fiber is released from the fiber releasing wheel, passes through the longitudinal wide guide wheel, the plurality of guide pulleys and the pair of guide wheels, and then reaches a fiber winding frame, and the guide wheel system base frame is further provided with a movable translation frame, an end of the translation frame is provided with a first tension wheel provided with a tension sensor, and the first tension wheel rotates against the fiber; the problem of guiding the fiber path during the winding of the fiber ring is solved.

Description

Technical Field

[0001] This invention relates to the field of optical fiber winding, and in particular to an optical fiber winding guide wheel system. Background Technology

[0002] Fiber optic ring devices are widely used in the field of gyroscope inertial systems, and stable and reliable fiber optic ring winding equipment is the foundation for fiber optic ring production.

[0003] Fiber optic winding typically starts from the middle, with both ends stored on fiber trays. Since the fiber entry position on the fiber ring changes constantly with the number of turns and layers during fiber routing, a guide wheel system is needed to guide the fiber path. By adjusting its position and angle, the fiber path can be redirected to avoid scratching the outer wall of the fiber. Summary of the Invention

[0004] This invention provides an optical fiber winding guide wheel system, which solves the problem of guiding the optical fiber path when winding an optical fiber ring.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an optical fiber surrounding guide wheel system, including a guide wheel system base frame, on which a near-fiber ring wheel group and a near-fiber release wheel group are provided. The near-fiber ring wheel group includes an obliquely arranged pair of rollers, which has a gap for the optical fiber to pass through. The near-fiber release wheel group includes a longitudinally wide guide wheel, and a plurality of fixed pulleys for guidance are provided between the longitudinally wide guide wheel and the pair of rollers. The optical fiber starts from the release wheel, passes around the longitudinally wide guide wheel, the plurality of fixed pulleys for guidance, and the pair of rollers, and reaches the optical fiber ring frame. The guide wheel system base frame is also provided with a movable translation frame, and the end of the translation frame is provided with a first tension wheel with a tension sensor. The first tension wheel rotates against the optical fiber.

[0006] In a preferred embodiment, the fiber-laying wheel assembly includes a third transverse fixed pulley and a fourth transverse fixed pulley, and a first tension wheel is located on one side of the third transverse fixed pulley and the fourth transverse fixed pulley. The first tension wheel compresses the optical fiber between the third transverse fixed pulley and the fourth transverse fixed pulley.

[0007] In a preferred embodiment, the guide wheel system base frame is also provided with a movable carriage, on which a movable pulley is provided. The optical fiber on the near fiber ring wheel assembly passes around the movable pulley and reaches the near fiber release wheel assembly. One end of the carriage is provided with a tension spring connected to the guide wheel system base frame.

[0008] In a preferred embodiment, the translation frame is further provided with a rotatable second tension wheel. The second tension wheel is coaxial with the first tension wheel and arranged at a certain distance. The near-fiber ring wheel group includes a first transverse fixed pulley and a second transverse fixed pulley. The second transverse fixed pulley and a third transverse fixed pulley are arranged coaxially. The second tension wheel squeezes the optical fiber between the first transverse fixed pulley and the second transverse fixed pulley. The first tension wheel is used to detect the optical fiber tension on the near-fiber release wheel group, and the second tension wheel is used to detect the optical fiber tension on the near-fiber ring wheel group.

[0009] In a preferred embodiment, a first custom magnet is provided on one side of the first transverse fixed pulley and rotates coaxially with the first transverse fixed pulley. A first magnetic sensor is provided on the guide wheel system base frame on one side of the first custom magnet. The first magnetic sensor is used to detect the periodic changes in the magnetic force of the first custom magnet.

[0010] In a preferred embodiment, the fiber feeding wheel assembly includes a third longitudinal fixed pulley, a second custom magnet that rotates coaxially with the third longitudinal fixed pulley is provided on one side of the third longitudinal fixed pulley, and a second magnetic sensor is provided on the guide wheel system base on one side of the second custom magnet. The second magnetic sensor is used to detect the periodic changes in the magnetic force of the second custom magnet.

[0011] In the preferred embodiment, the outer edges of the third longitudinal fixed pulley are provided with inclined baffles.

[0012] In a preferred embodiment, a second pulley is provided that rotates synchronously with the first transverse fixed pulley. A relay drive motor is provided on one side of the first transverse fixed pulley, and a first pulley is provided at the shaft end of the relay drive motor. A transmission belt for transmission is provided between the first pulley and the second pulley.

[0013] The beneficial effects of the present invention are as follows: the fiber guide wheel assembly guides the fiber through a series of guide wheels and integrates a fiber tension detection component to detect the fiber tension during winding and monitor the fiber tension in real time. The cumulative value of the rotation angle of the fiber guide wheel is detected to obtain the fiber winding length data, so as to realize the fixed length winding of the fiber ring and ensure the geometric symmetry of the fiber ring. The fiber tension detection component and the fiber length detection chip circuit component can switch between standby and working positions, making them flexible to use; The magnetic sensor can detect the rotation signal of the fiber guide wheel without passing through the brush, thus avoiding damping of the fiber guide wheel's rotation. Attached Figure Description

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0015] Figure 1 This is a front view of the present invention.

[0016] Figure 2 This is a top view of the present invention.

[0017] Figure 3 This is an application embodiment diagram of the present invention.

[0018] Figure 4 This is a side sectional view of the present invention.

[0019] Figure 5 This is a schematic diagram of the movable pulley of the present invention.

[0020] Figure 6 This is a schematic diagram of the tension detection principle of the present invention.

[0021] Figure 7 This is a schematic diagram of the custom magnet of the present invention.

[0022] Figure 8 This is a graph showing the change in magnetic field strength according to the present invention.

[0023] Figure 9 This is a schematic diagram of the dual tension detection of the present invention.

[0024] Figure 10 This is a schematic diagram of the longitudinal wide guide wheel oblique edge of the present invention.

[0025] Figure 11 This is a schematic diagram of the fiber winding of the guide wheel of the present invention.

[0026] In the diagram: 1. Near-fiber ring wheel assembly; 101. Roller assembly; 102. First longitudinal fixed pulley; 103. First transverse fixed pulley; 104. Second transverse fixed pulley; 105. Second longitudinal fixed pulley; 106. Movable pulley; 107. Carriage; 108. Tension spring; 109. First custom magnet; 110. First magnetic sensor; 111. Second tension wheel; 112. Relay drive motor; 113. First pulley; 114. Second pulley; 115. Belt; 2. Near-fiber feeding wheel assembly; 201. Third longitudinal fixed pulley; 202. Fourth transverse fixed pulley; 203. Longitudinal wide guide wheel; 204. First tension wheel; 205. Translation frame; 206. Tension sensor; 207. Translation drive motor; 208. Second custom magnet; 209. Second magnetic sensor; 210. Inclined stop; 3. Fiber feeding wheel; 4. Fiber ring frame. Detailed Implementation

[0027] Example 1: like Figure 1-11In this paper, an optical fiber guiding wheel system includes a guide wheel system base frame. The guide wheel system base frame is provided with a near-fiber ring wheel group 1 and a near-fiber release wheel group 2. The near-fiber ring wheel group 1 includes an obliquely arranged pair of rollers 101. The pair of rollers 101 has a gap for the optical fiber to pass through. The near-fiber release wheel group 2 includes a longitudinally wide guide wheel 204. A plurality of fixed pulleys for guidance are provided between the longitudinally wide guide wheel 204 and the pair of rollers 101. The optical fiber starts from the release wheel 3, passes around the longitudinally wide guide wheel 204, the plurality of fixed pulleys for guidance and the pair of rollers 101 and reaches the optical fiber ring frame 4. The guide wheel system base frame is also provided with a movable translation frame 206. The end of the translation frame 206 is provided with a first tension wheel 205 with a tension sensor 207. The first tension wheel 205 rotates against the optical fiber.

[0028] The roller assembly 101 includes two parallel, spaced-apart long rollers with a gap equal to the diameter of the optical fiber. When the optical fiber is wound and arranged on the optical fiber ring frame 4, its position changes back and forth. When the number of fiber layers changes, its position also changes. Therefore, the roller assembly 101 needs to be arranged obliquely.

[0029] In a preferred embodiment, the fiber feed wheel assembly 2 includes a third transverse fixed pulley 202 and a fourth transverse fixed pulley 203. A first tension wheel 205 is disposed on one side of the third transverse fixed pulley 202 and the fourth transverse fixed pulley 203. The first tension wheel 205 compresses the optical fiber between the third transverse fixed pulley 202 and the fourth transverse fixed pulley 203.

[0030] The third transverse fixed pulley 202 and the fourth transverse fixed pulley 203 are connected to the guide wheel system base frame via a connecting shaft, and the third transverse fixed pulley 202 and the fourth transverse fixed pulley 203 are rotatable. The translation frame 206 is slidably connected to the guide wheel system base frame via a guide rail slider or guide rod, and the translation drive motor 208 drives the translation frame 206 to move via a lead screw device or a synchronous belt device. When it is necessary to monitor the fiber tension, the translation drive motor 208 drives the translation frame 206 forward, causing the first tension wheel 205 to abut against the midpoint of the fiber segment between the third transverse fixed pulley 202 and the fourth transverse fixed pulley 203. This segment of the fiber is bent inward at an obtuse angle, and the direction of movement of the first tension wheel 205 is the angle bisector of the fiber bending angle. At this time, the force F measured by the tension sensor 207 forms a three-force balance with the tension T in the fiber on both sides of the midpoint. Since F is known, the value of T can be calculated from this.

[0031] When the fiber tension is detected to increase, the fiber feeding wheel 3 rotates faster to increase the fiber feeding speed and reduce the fiber tension. When the fiber tension is detected to decrease, the fiber feeding wheel 3 rotates slower to reduce the fiber feeding speed and increase the fiber tension.

[0032] In a preferred embodiment, the guide wheel system base frame is also provided with a movable slide 107, on which a movable pulley 106 is provided. The optical fiber on the near fiber ring wheel assembly 1 passes around the movable pulley 106 and reaches the near fiber release wheel assembly 2. One end of the slide 107 is provided with a tension spring 108 connected to the guide wheel system base frame.

[0033] The slide 107 is slidably connected to the guide wheel system frame via a cross roller guide rail. The slide 107 moves vertically. A tension spring 108 holds the slide 107 to balance part of the gravity. The optical fiber passes under the driven pulley 106 to balance the remaining gravity. When the optical fiber tension changes, the vertical position of the driven pulley 106 changes accordingly until gravity, optical fiber tension, and spring force are rebalanced.

[0034] When the translation frame 206 moves laterally and the first tension wheel 205 squeezes the optical fiber, the movable pulley 106 moves upward to reduce the instantaneous surge in tension and prevent the optical fiber from breaking.

[0035] Since this guide wheel system is mainly used in automatic winding equipment, the fiber feeding tray mechanism needs multi-axis movement and rotation to meet the requirements of automatic tray changing, and the equipment also needs to be miniaturized. Therefore, the guide wheel system is more complex than traditional manual tray changing equipment, adopting a three-dimensional multi-layer design and integrating a tension detection mechanism and a buffer pulley mechanism. This also results in the optical fiber passing through multiple wheel sets, and the frictional resistance between the guide wheels and the sidewalls of the optical fiber along the way affects the tension of local sections of the optical fiber, causing the actual tension of the optical fiber near the feeding wheel and the end near the optical fiber ring skeleton to be unequal. The single tension detection mechanism can only accurately detect the tension of the optical fiber in wheel set 2 near the feeding wheel, that is, the tension close to the feeding wheel, while the tension of the optical fiber near the optical fiber ring skeleton is difficult to detect.

[0036] In a preferred embodiment, the translation frame 206 is further provided with a rotatable second tension wheel 111. The second tension wheel 111 is coaxial with the first tension wheel 205 and arranged at a certain distance. The near-fiber ring wheel group 1 includes a first transverse fixed pulley 103 and a second transverse fixed pulley 104. The second transverse fixed pulley 104 is coaxial with the third transverse fixed pulley 202. The second tension wheel 111 squeezes the optical fiber between the first transverse fixed pulley 103 and the second transverse fixed pulley 104. The first tension wheel 205 is used to detect the optical fiber tension on the near-fiber release wheel group 2, and the second tension wheel 111 is used to detect the optical fiber tension on the near-fiber ring wheel group 1.

[0037] Each of the first tension wheel 205 and the second tension wheel 111 is equipped with an independent tension sensor 207, which is connected to the translation frame 206 via the tension sensor 207, and the detection principle is the same. After the fiber segments between the first transverse fixed pulley 103 and the second transverse fixed pulley 104, and between the third transverse fixed pulley 202 and the fourth transverse fixed pulley 203 are straightened, they are in a parallel state. Using the first tension wheel 205 and the second tension wheel 111 of equal diameter to simultaneously compress the two fiber segments, the tension in the middle section of the fiber near the fiber ring wheel group 1 and the fiber feeding wheel group 2 can be detected simultaneously. When the tension feedback from the tension sensor 207 of the second tension wheel 111 is found to be too high or too low, the rotation speed of the fiber ring frame 4 is mainly considered for adjustment; when the tension feedback from the tension sensor 207 of the first tension wheel 205 is found to be too high or too low, the rotation speed of the fiber feeding wheel 3 is mainly considered for adjustment. This results in a faster tension feedback adjustment response and more accurate tension adjustment.

[0038] In a preferred embodiment, a first custom magnet 109 is provided on one side of the first transverse fixed pulley 103 and rotates coaxially with the first transverse fixed pulley 103. A first magnetic sensor 110 is provided on the guide wheel system base frame on one side of the first custom magnet 109. The first magnetic sensor 110 is used to detect the periodic changes in the magnetic force of the first custom magnet 109.

[0039] In a preferred embodiment, a second custom magnet 209 is provided on one side of the third longitudinal fixed pulley 201 and rotates coaxially with the third longitudinal fixed pulley 201. A second magnetic sensor 210 is provided on the guide wheel system base frame on one side of the second custom magnet 209. The second magnetic sensor 210 is used to detect the periodic changes in the magnetic force of the second custom magnet 209.

[0040] The custom magnet is disc-shaped, with one half being the N pole and the other half being the S pole. The magnetic sensor detects that the magnetic field strength changes periodically in a sine curve. By measuring the rotation angle corresponding to the magnetic field strength, and by calculating the fiber optic traction length based on the rotation angle and the wheel diameter, fixed-length winding is achieved.

[0041] In the preferred embodiment, the third longitudinal fixed pulley 201 has inclined baffles 211 on both sides of its outer edge.

[0042] In a preferred embodiment, a second pulley 114 is provided that rotates synchronously with the first transverse fixed pulley 103. A relay drive motor 112 is provided on one side of the first transverse fixed pulley 103. A first pulley 113 is provided at the shaft end of the relay drive motor 112. A transmission belt 115 for transmission is provided between the first pulley 113 and the second pulley 114.

[0043] The relay drive motor 112 drives the first transverse fixed pulley 103 to rotate, and the linear velocity of the optical fiber at this point is between the linear velocity of the fiber feeding wheel 3 and the optical fiber ring skeleton 4.

[0044] Overall fiber optic routing: The fiber optic cable starts to loop from the middle. Half of the fiber optic cable starts from the fiber optic ring skeleton 4 and passes through the roller group 101 to restrict the displacement in one direction. Then it passes through the first longitudinal fixed pulley 102 and the first transverse fixed pulley 103, where the transverse and longitudinal positions of the fiber optic cable are restricted. Subsequently, the fiber optic cable passes around the second transverse fixed pulley 104 and the second longitudinal fixed pulley 105 to reach the movable pulley 106. After passing around the movable pulley 106, the third longitudinal fixed pulley 201, the third transverse fixed pulley 202, and the fourth transverse fixed pulley 203, it is guided by the longitudinal wide guide wheel 204 and wound around the fiber release wheel 3.

[0045] Example 2: A separable optical fiber winding tension and length detection mechanism includes an optical fiber guide wheel assembly, an optical fiber tension detection assembly, an optical fiber length detection chip circuit assembly, a rotation calibration assembly, and a translation module.

[0046] The fiber optic guide wheel assembly includes a series of V-groove guide wheels, which control the path of the optical fiber.

[0047] The fiber tension detection component uses a tension sensor to measure tension. Under the fiber tension applied by the fiber tension wheel, the tension sensor undergoes slight deformation, thereby generating an analog electrical signal. This electrical signal is linearly related to the fiber tension.

[0048] The fiber optic length detection chip circuit assembly detects the rotation angle of the fiber guide wheel through the chip circuit. The fiber guide wheel is equipped with a custom magnet. The magnet rotates with the fiber guide wheel, thereby generating a change in the magnetic field. This change in the magnetic field can be sensed by the chip circuit, thus obtaining the rotation angle of the fiber guide wheel. This angle value is converted into the fiber winding length.

[0049] The rotation calibration component includes a stepper motor, a motor-driven V-shaped pulley, a belt, and a length-measuring fiber guide pulley. The stepper motor drives the length-measuring fiber guide pulley to rotate via a circular belt with a transmission ratio of 1:1. The length-measuring fiber guide pulley rotates at a certain angle α under the drive of the motor, thereby generating electromagnetic induction on the length detection chip circuit. The functional relationship between the electrical signal generated by this electromagnetic induction and the angle α can be obtained through linear regression of multiple sets of data, thereby achieving length calibration.

[0050] The translation module drives the fiber tension detection component and the fiber length detection chip circuit component to move from the standby position to the working position. This causes the fiber tension wheel in the fiber tension detection component to compress the fiber, forming an angle that converts the fiber tension into a lateral force on the tension wheel, which can then be detected by the tension sensor. In the working position, the fiber length detection chip circuit is located directly above the custom magnet on the length-measuring fiber guide wheel, thus effectively detecting the rotation angle of the length-measuring fiber guide wheel.

[0051] The motor-driven V-wheel is mounted on the rotating shaft of the stepper motor and rotates under the motor's drive. The tension wheel is mounted on the sensing shaft of the tension sensor, so the force on the tension wheel can be directly converted into the force on the tension sensor. At this time, the fiber tension detection component and the fiber length detection chip circuit component are in the standby position.

[0052] When the fiber tension detection component moves to the working position, the fibers on both sides of the tension wheel form an angle θ. At this time, the fiber tension T can be transmitted to the tension wheel as a horizontal force F through vector calculation. The tension sensor then senses F and, after reverse calculation, obtains the fiber tension value T = F / [2*cos(θ / 2)]. A custom magnet is coaxially mounted on the length-measuring fiber guide wheel and rotates synchronously with it. When the fiber passes through the length-measuring fiber guide wheel along the V-groove on the wheel during the winding process, the linear velocity of the fiber is converted into the angular velocity of the length-measuring fiber guide wheel, and the length traveled by the fiber is converted into the cumulative rotation angle α of the length-measuring fiber guide wheel. This angle α is sensed by the chip circuit and, after conversion, the fiber length can be obtained.

[0053] The sensing chip circuit is located directly above the length-measuring fiber guide wheel, only a tiny gap away from the custom magnet. The sensing chip on the circuit board can effectively detect the magnetic field changes caused by the rotation of the custom magnet. A taut circular belt is installed in the V-groove of the motor-driven V-wheel and the length-measuring fiber guide wheel. Driven by the circular belt, the motor-driven V-wheel rotates synchronously with the length-measuring fiber guide wheel. The rotation angle of the two wheels can be accurately calculated by the number of stepper motor pulses. The magnetic field change caused by this rotation angle is sensed in the chip circuit to form an electrical signal. Thus, the exact functional relationship between the electrical signal of the chip circuit and the rotation angle can be obtained, thereby achieving length detection calibration.

[0054] The fiber guide wheel assembly guides the fiber through a series of V-groove guide wheels, providing conditions for fiber winding tension and length detection. The fiber tension detection assembly detects the fiber tension in real time during winding. The fiber length detection chip circuit assembly detects the cumulative value of the rotation angle of the length-counting guide wheel to obtain the fiber winding length data. The rotation calibration assembly calibrates the length detection of the fiber length detection chip circuit assembly.

[0055] When one section of optical fiber is wound, the optical fiber tension detection component and the optical fiber length detection chip circuit component switch to the standby position. During the winding of the next section of optical fiber, the tension and length are detected by the corresponding mechanism in the other section of the two symmetrically distributed optical fibers to be wound, and so on in an alternating cycle.

[0056] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A fiber optic guided wheel system, characterized in that: The system includes a guide wheel system base frame, on which a near-fiber ring wheel assembly (1) and a near-fiber release wheel assembly (2) are provided. The near-fiber ring wheel assembly (1) includes an obliquely arranged pair of rollers (101), which has a gap for the fiber to pass through. The near-fiber release wheel assembly (2) includes a longitudinal wide guide wheel (204), and multiple fixed pulleys for guidance are provided between the longitudinal wide guide wheel (204) and the pair of rollers (101). The fiber starts from the release wheel (3), passes around the longitudinal wide guide wheel (204), the multiple fixed pulleys for guidance, and the pair of rollers (101), and reaches the fiber ring frame (4). The guide wheel system base frame is also provided with a movable translation frame (206), and the end of the translation frame (206) is provided with a first tension wheel (205) with a tension sensor (207). The first tension wheel (205) rotates against the fiber. The fiber feeding wheel assembly (2) includes a third transverse fixed pulley (202) and a fourth transverse fixed pulley (203). A first tension wheel (205) is located on one side of the third transverse fixed pulley (202) and the fourth transverse fixed pulley (203). The first tension wheel (205) squeezes the optical fiber between the third transverse fixed pulley (202) and the fourth transverse fixed pulley (203). The translation frame (206) is also equipped with a rotatable second tension wheel (111). The second tension wheel (111) is coaxial with the first tension wheel (205) and arranged at a certain distance. The near fiber ring wheel group (1) includes a first transverse fixed pulley (103) and a second transverse fixed pulley (104). The second transverse fixed pulley (104) is coaxial with the third transverse fixed pulley (202). The second tension wheel (111) squeezes the optical fiber between the first transverse fixed pulley (103) and the second transverse fixed pulley (104). The first tension wheel (205) is used to detect the optical fiber tension on the near fiber release wheel group (2), and the second tension wheel (111) is used to detect the optical fiber tension on the near fiber ring wheel group (1).

2. The fiber optic guided wheel system according to claim 1, characterized in that: The guide wheel system base frame is also provided with a movable slide (107), and the slide (107) is provided with a movable pulley (106). The optical fiber on the near fiber ring wheel assembly (1) passes around the movable pulley (106) and reaches the near fiber release wheel assembly (2). One end of the slide (107) is provided with a tension spring (108) connected to the guide wheel system base frame.

3. The fiber optic guided wheel system according to claim 1, characterized in that: A first custom magnet (109) is provided on one side of the first transverse fixed pulley (103) and rotates coaxially with the first transverse fixed pulley (103). A first magnetic sensor (110) is provided on the guide wheel system base frame on one side of the first custom magnet (109). The first magnetic sensor (110) is used to detect the periodic change of the magnetic force of the first custom magnet (109).

4. The fiber optic guided wheel system according to claim 3, characterized in that: The fiber feeding wheel assembly (2) includes a third longitudinal fixed pulley (201). A second custom magnet (209) is provided on one side of the third longitudinal fixed pulley (201) and rotates coaxially with the third longitudinal fixed pulley (201). A second magnetic sensor (210) is provided on the guide wheel system base frame on one side of the second custom magnet (209). The second magnetic sensor (210) is used to detect the periodic changes in the magnetic force of the second custom magnet (209).

5. The fiber optic guided wheel system according to claim 4, characterized in that: The third longitudinal fixed pulley (201) has inclined guards (211) on both sides of its outer edge.

6. The fiber optic guided wheel system according to claim 1, characterized in that: It is also provided with a second pulley (114) that rotates synchronously with the first transverse fixed pulley (103). A relay drive motor (112) is provided on one side of the first transverse fixed pulley (103), and a first pulley (113) is provided at the shaft end of the relay drive motor (112). A transmission belt (115) for transmission is provided between the first pulley (113) and the second pulley (114).

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