阅读说明：本技术 一种电动汽车及其工作方法 (Electric automobile and working method thereof ) 是由 不公告发明人 于 2018-11-06 设计创作，主要内容包括：一种电动汽车及其工作方法,包括皮带自动张紧装置,该装置包括张紧皮带、皮带轮轴、张紧皮带轮、压力传感器、主控制器、轴承、压板、弹簧、张紧支架、张紧电机、蜗杆、蜗轮、磁环、传感器、固定架、支架轴和电机驱动器；支架轴与固定架固定连接；张紧支架转动连接在支架轴上；蜗轮固定连接在张紧支架；蜗杆与张紧电机和蜗轮传动连接；磁环固定连接在张紧电机的输出轴上；传感器固定连接在张紧电机的机体上；皮带轮轴固定连接在张紧支架上且具有径向滑槽；轴承套设在皮带轮轴的外周；弹簧和压力传感器均设置在径向滑槽中；张紧皮带轮套装在轴承的外周；压力传感器、电机驱动器和传感器均与主控制器电连接。本发明可实现张紧皮带松掉后自动张紧,张紧力大小自动控制。(An electric automobile and a working method thereof comprise an automatic belt tensioning device, wherein the automatic belt tensioning device comprises a tensioning belt, a belt pulley shaft, a tensioning belt pulley, a pressure sensor, a main controller, a bearing, a pressing plate, a spring, a tensioning bracket, a tensioning motor, a worm gear, a magnetic ring, a sensor, a fixing frame, a bracket shaft and a motor driver; the bracket shaft is fixedly connected with the fixed bracket; the tensioning bracket is rotationally connected to the bracket shaft; the worm wheel is fixedly connected with the tensioning bracket; the worm is in transmission connection with the tensioning motor and the worm wheel; the magnetic ring is fixedly connected to an output shaft of the tensioning motor; the sensor is fixedly connected to the body of the tensioning motor; the belt pulley shaft is fixedly connected to the tensioning bracket and is provided with a radial sliding chute; the bearing is sleeved on the periphery of the belt pulley shaft; the spring and the pressure sensor are both arranged in the radial sliding groove; the tensioning belt pulley is sleeved on the periphery of the bearing; the pressure sensor, the motor driver and the sensor are all electrically connected with the main controller. The invention can realize automatic tensioning after the tensioning belt is loosened and automatically control the tension.)

1. An operating method of an electric vehicle, the electric vehicle including an automatic belt tensioner, the automatic belt tensioner including a tension belt (51); the method is characterized in that: the device is characterized by also comprising a belt pulley shaft (1), a tensioning belt pulley (2), a pressure sensor (3), a main controller (4), a bearing (5), a pressing plate (6), a spring (7), a tensioning bracket (8), a tensioning motor (9), a worm (10), a worm wheel (11), a magnetic ring (12), a sensor (13), a fixing frame (14), a bracket shaft (15) and a motor driver (16); the support shaft (15) is fixedly connected with the fixed frame (14); one end part of the tensioning bracket (8) is rotatably connected to the bracket shaft (15); the worm wheel (11) is fixedly connected to one end of the tensioning bracket (8), and the worm wheel (11) and the bracket shaft (15) are coaxially arranged; the machine body of the tensioning motor (9) is fixedly connected to the fixing frame (14), and an output shaft of the tensioning motor (9) is in transmission connection with one end of the worm (10); the worm (10) is rotationally connected to the fixed frame (14), and the other end of the worm (10) is in transmission connection with the worm wheel (11) to form a worm and gear mechanism; the magnetic ring (12) is fixedly connected to an output shaft of the tensioning motor (9); the sensor (13) is fixedly connected to the body of the tensioning motor (9) and corresponds to the magnetic ring (12); the pulley shaft (1) is fixedly connected to the other end of the tensioning bracket (8), and a radial sliding groove (1-1) is formed in the pulley shaft (1); the bearing (5) is sleeved on the periphery of the belt pulley shaft (1), and an inner ring of the bearing (5) is in clearance fit with the periphery of the belt pulley shaft (1); the pressure plate (6) is connected in the radial sliding groove (1-1) in a sliding manner, and one end of the pressure plate (6) is provided with an arc surface (6-1) matched with the inner ring of the bearing (5); the spring (7) is positioned in the radial sliding groove (1-1), one end of the spring (7) is abutted against the bottom end of the radial sliding groove (1-1), and the other end of the spring (7) is abutted against the other end of the pressing plate (6); the pressure sensor (3) is arranged in a radial sliding groove (1-1) of the belt pulley shaft (1); the tensioning belt pulley (2) is sleeved on the periphery of the bearing (5); the pressure sensor (3), the motor driver (16) and the sensor (13) are electrically connected or wirelessly communicated with the main controller (4); the tensioning motor (9) is electrically connected or wirelessly communicated with a motor driver (16); when the pressure value of the pressure sensor (3) is equal to 0, the main controller (4) controls the output shaft of the tensioning motor (9) to start rotating through the motor driver (16); when the rotating speed value of the sensor (13) is smaller than the set rotating speed value in the main controller (4), the main controller (4) controls the output shaft of the tensioning motor (9) to stop rotating through a motor driver (16);

the working method comprises the following steps: after the tensioning belt is tensioned, the resistance of the tensioning support rotating clockwise around the axis of the support shaft can be increased, the resistance of the worm gear rotating clockwise can be increased, the rotating speed of an output shaft of the tensioning motor and the rotating speed of the worm are reduced, when the rotating speed value of the sensor is smaller than the set rotating speed value in the main controller, the main controller controls the output shaft of the tensioning motor to stop rotating through the motor driver, at the moment, the worm does not rotate any more, the worm gear does not rotate any more, the tensioning belt pulley does not rotate clockwise around the axis of the support shaft, the tensioning belt pulley does not move to the lower right any more, the tensioning process of the tensioning belt is finished, the tensioning force of the tensioning belt does not increase.

2. The method of operation of claim 1, wherein: also comprises a sensor bracket (17); the sensor (13) is fixedly connected to the body of the tensioning motor (9) through a sensor bracket (17).

3. The method of operation of claim 1, wherein: also comprises a coupling (18); an output shaft of the tensioning motor (9) is in transmission connection with one end of the worm (10) through a coupler (18).

4. The method of operation of claim 1, wherein: the tension belt (51) is wound on the outer peripheral surfaces of a drive pulley (55) of a drive motor of an electric automobile, a first driven pulley (56) of a cooling water pump, a second driven pulley (57) of a steering oil pump, a third driven pulley 58 of an air compressor and the tension pulley (2) of the present invention, and the pressure sensor (3) is located on the bisector of the angle formed by the tension belt (51) and the tension pulley (2).

Technical Field

The invention relates to an electric automobile, in particular to an electric automobile and a working method thereof.

Background

The electric automobile is a complex product, and relates to a plurality of systems such as heat dissipation, steering, braking, pneumatics and the like, which all need a power source for driving, for example, a cooling water pump is needed as the power source for the heat dissipation system; the steering system needs a steering oil pump as a power source; pneumatic systems require an air compressor as a power source. The power sources are integrated and controlled uniformly, so that the arrangement space of the chassis can be saved, and the cost is saved. In the prior art, the electric vehicle is generally powered by a driving motor, and as shown in fig. 8, the driving motor drives a cooling water pump, a steering oil pump and an air compressor to synchronously rotate through a tension belt 51. Specifically, a driving pulley 55 is arranged on the driving motor, a first driven pulley 56 is arranged on the cooling water pump, a second driven pulley 57 is arranged on the steering oil pump, a third driven pulley 58 is arranged on the air compressor, and the tensioning belt 51 is wound on the driving pulley 55, the first driven pulley 56, the second driven pulley 57 and the third driven pulley 58, so that the rotary power on the driving motor can be transmitted to the cooling water pump, the steering oil pump and the air compressor, and the normal operation of the cooling water pump, the steering oil pump and the air compressor is realized. As an important part of energy transmission, whether the tension belt 51 works normally or not plays an important role in the transmission process of power, and an important factor influencing the transmission efficiency of the tension belt 51 is the tension force, when the tension force of the tension belt 51 is insufficient, the capacity of transmitting load is low, the efficiency is low, and a belt wheel is heated rapidly, so that the belt is worn; when the tension of the tension belt 51 is too large, the life of the tension belt 51 is reduced, the load on the shaft and the bearing is increased, and the bearing is heated and worn, so that an appropriate tension is an important factor for ensuring the normal operation of the transmission of the tension belt 51. The belt tensioning device of the electric vehicle in the prior art cannot automatically tension the tensioning belt 51 after the tensioning belt is loosened, and the tension cannot be automatically controlled, so that insufficient tension or excessive tension is caused, and the transmission efficiency of the tensioning belt 51 is affected.

Disclosure of Invention

The invention aims to provide an electric automobile with an automatic belt tensioning device, wherein the automatic belt tensioning device can automatically tension a tensioned belt after the tensioned belt is loosened, and the tension can be automatically controlled.

In order to achieve the purpose, the invention adopts the following technical scheme: an electric vehicle includes an automatic belt tensioner including a tension belt; the device also comprises a belt pulley shaft, a tensioning belt pulley, a pressure sensor, a main controller, a bearing, a pressing plate, a spring, a tensioning bracket, a tensioning motor, a worm wheel, a magnetic ring, a sensor, a fixing frame, a bracket shaft and a motor driver; the bracket shaft is fixedly connected with the fixed frame; one end part of the tensioning bracket is rotatably connected to the bracket shaft; the worm wheel is fixedly connected to one end of the tensioning bracket and is coaxially arranged with the bracket shaft; the machine body of the tensioning motor is fixedly connected to the fixing frame, and an output shaft of the tensioning motor is in transmission connection with one end of the worm; the worm is rotationally connected to the fixed frame, and the other end of the worm is in transmission connection with the worm wheel to form a worm and gear mechanism; the magnetic ring is fixedly connected to an output shaft of the tensioning motor; the sensor is fixedly connected to the body of the tensioning motor and corresponds to the magnetic ring; the belt pulley shaft is fixedly connected to the other end of the tensioning bracket, and a radial sliding groove is formed in the belt pulley shaft; the bearing is sleeved on the periphery of the belt pulley shaft, and an inner ring of the bearing is in clearance fit with the periphery of the belt pulley shaft; the pressing plate is connected in the radial sliding groove in a sliding mode, and one end of the pressing plate is provided with an arc surface matched with the inner ring of the bearing; the spring is positioned in the radial sliding groove, one end of the spring is abutted against the bottom end of the radial sliding groove, and the other end of the spring is abutted against the other end of the pressing plate; the pressure sensor is arranged in a radial sliding groove of the belt pulley shaft; the tensioning belt pulley is sleeved on the periphery of the bearing; the pressure sensor, the motor driver and the sensor are electrically connected or wirelessly communicated with the main controller; the tensioning motor is electrically connected or wirelessly communicated with the motor driver; when the pressure value of the pressure sensor is equal to 0, the main controller controls the output shaft of the tensioning motor to start rotating through the motor driver; when the rotating speed value of the sensor is smaller than the set rotating speed value in the main controller, the main controller controls the output shaft of the tensioning motor to stop rotating through the motor driver.

The sensor support is also included; the sensor is fixedly connected to the body of the tensioning motor through a sensor support.

The device also comprises a coupler; and an output shaft of the tensioning motor is in transmission connection with one end of the worm through a coupler.

The invention has the following positive effects: (1) the bracket shaft is fixedly connected with the fixed frame; one end part of the tensioning bracket is rotatably connected to the bracket shaft; the worm wheel is fixedly connected to one end of the tensioning bracket and is coaxially arranged with the bracket shaft; the machine body of the tensioning motor is fixedly connected to the fixing frame, and an output shaft of the tensioning motor is in transmission connection with one end of the worm; the worm is rotationally connected to the fixed frame, and the other end of the worm is in transmission connection with the worm wheel to form a worm and gear mechanism; the magnetic ring is fixedly connected to an output shaft of the tensioning motor; the sensor is fixedly connected to the body of the tensioning motor and corresponds to the magnetic ring; the belt pulley shaft is fixedly connected to the other end of the tensioning bracket and is provided with a radial sliding groove; the bearing is sleeved on the periphery of the belt pulley shaft, and an inner ring of the bearing is in clearance fit with the periphery of the belt pulley shaft; the pressing plate is connected in the radial sliding groove in a sliding manner; the spring is positioned in the radial sliding groove, one end of the spring is abutted against the bottom end of the radial sliding groove, and the other end of the spring is abutted against the pressing plate; the pressure sensor is arranged in a radial sliding groove of the belt pulley shaft; the tensioning belt pulley is sleeved on the periphery of the bearing; the pressure sensor, the motor driver and the sensor are electrically connected or wirelessly communicated with the main controller; the tensioning motor is electrically connected or wirelessly communicated with the motor driver, and when the device is used, the tensioning belt is wound on the peripheral surfaces of a driving belt pulley of a driving motor of an electric automobile, a first driven belt pulley of a cooling water pump, a second driven belt pulley of a steering oil pump, a third driven belt pulley of an air compressor and the tensioning belt pulley of the device, so that after the tensioning belt is loosened, the pressing plate moves outwards in the radial direction under the action of the spring, the other end of the pressure sensor is separated from the pressing plate, the pressure value of the pressure sensor is equal to 0, the main controller controls the output shaft of the tensioning motor to start rotating through the motor driver, the worm rotates synchronously along with the output shaft of the tensioning motor to drive the worm wheel to rotate clockwise, the tensioning bracket rotates clockwise around the axis of the bracket shaft, the bearing arranged on the periphery of the belt wheel shaft and the tensioning belt pulley sleeved on the periphery of the bearing also rotate, the tensioning belt wheel moves towards the lower right direction, so that the tensioning belt is automatically tensioned, namely the tensioning belt can be automatically tensioned after being loosened. After the tensioning belt is tensioned, the resistance of the tensioning support rotating clockwise around the axis of the support shaft can be increased, the resistance of the worm gear rotating clockwise can be increased, the rotating speed of an output shaft of the tensioning motor and the rotating speed of the worm are reduced, when the rotating speed value of the sensor is smaller than the set rotating speed value in the main controller, the main controller controls the output shaft of the tensioning motor to stop rotating through the motor driver, at the moment, the worm does not rotate any more, the worm gear does not rotate any more, the tensioning belt pulley does not rotate clockwise around the axis of the support shaft, the tensioning belt pulley does not move to the lower right any more, the tensioning process of the tensioning belt is finished, the tensioning force of the tensioning belt does not increase.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic sectional view A-A of FIG. 1;

FIG. 3 is an enlarged schematic view of the pulley shaft, tensioner pulley and bearing connection of FIG. 2;

FIG. 4 is a schematic cross-sectional view B-B of FIG. 3;

fig. 5 is an enlarged schematic view of the pulley shaft of fig. 4;

FIG. 6 is a schematic cross-sectional view C-C of FIG. 5;

FIG. 7 is a schematic diagram of the pressure sensor, main controller, tensioning motor, sensor and motor driver connections of the present invention.

FIG. 8 is a schematic diagram of the connection of the present invention to a tensioned belt, a drive pulley, a first driven pulley, a second driven pulley and a third driven pulley of an electric vehicle.

The reference numbers in the above figures are as follows: the device comprises a pulley shaft 1, a radial sliding groove 1-1, a tensioning pulley 2, a pressure sensor 3, a main controller 4, a bearing 5, a pressing plate 6, an arc surface 6-1, a spring 7, a tensioning support 8, a tensioning motor 9, a worm 10, a worm wheel 11, a magnetic ring 12, a sensor 13, a fixed frame 14, a support shaft 15, a motor driver 16, a sensor support 17, a coupling 18, a copper sleeve 19, a tensioning belt 51, a driving pulley 55, a first driven pulley 56, a second driven pulley 57 and a third driven pulley 58.

Detailed Description

The invention is further described below with reference to the accompanying drawings and the examples given.

As shown in fig. 1 to 7, an automatic belt tensioner for an electric vehicle includes a tension belt 51; the device also comprises a pulley shaft 1, a tensioning pulley 2, a pressure sensor 3, a main controller 4, a bearing 5, a pressure plate 6, a spring 7, a tensioning bracket 8, a tensioning motor 9, a worm 10, a worm wheel 11, a magnetic ring 12, a sensor 13, a fixed frame 14, a bracket shaft 15 and a motor driver 16; in this embodiment, the magnetic ring 12 is a two-pole magnetic ring manufactured by Jiangsu Xinxu magnetoelectric technology Limited. The sensor 13 is a Hall sensor with the model MT 4401. The pressure sensor 3 is a pressure sensor with the model number LH-Y03-D. The tensioning motor 9 is a servomotor of the type TLSM 04-M00330. The main controller 4 is a PLC programmable controller, a Mitsubishi FX2NC-PLC programmable controller is selected, and the motor driver 16 is a direct current motor driving board of the type LMD 18200T. As shown in fig. 2, the support shaft 15 is fixedly connected with the fixing frame 14; the fixed connection mode can be a direct welding connection mode or a connection mode through a fastening piece. One end part of the tensioning bracket 8 is rotatably connected to a bracket shaft 15 through a bearing; the worm wheel 11 is fixedly connected to one end of the tensioning bracket 8, and the worm wheel 11 and the bracket shaft 15 are coaxially arranged; in this embodiment, the worm wheel 11 is fixedly connected to one end of the tension bracket 8 by a fastener. As shown in fig. 1, the body of the tensioning motor 9 is fixedly connected to the fixing frame 14 through a fastener, and an output shaft of the tensioning motor 9 is in transmission connection with one end of the worm 10; when the output shaft of the tensioning motor 9 rotates, the worm 10 rotates synchronously with the output shaft of the tensioning motor 9. The worm 10 is rotatably connected to the fixed frame 14 through a copper bush 19, and the other end of the worm 10 is in transmission connection with the worm wheel 11 to form a worm and gear mechanism; the magnetic ring 12 is fixedly connected to an output shaft of the tensioning motor 9; in this embodiment, the magnetic ring 12 is adhered to the output shaft of the tension motor 9, and when the output shaft of the tension motor 9 rotates, the magnetic ring 12 can rotate synchronously. The sensor 13 is fixedly connected to the body of the tensioning motor 9 and corresponds to the magnetic ring 12; as shown in fig. 2 and 6, the pulley shaft 1 is fixedly connected to the other end of the tension bracket 8, and the pulley shaft 1 is provided with a radial sliding groove 1-1; in this embodiment, the pulley shaft 1 is fixedly connected to the other end portion of the tension bracket 8 by a fastener. As shown in fig. 2 to 4, the bearing 5 is sleeved on the periphery of the pulley shaft 1, and an inner ring of the bearing 5 forms clearance fit with the periphery of the pulley shaft 1; as shown in fig. 6, the pressure plate 6 is slidably connected in the radial sliding groove 1-1, and one end of the pressure plate 6 is provided with an arc surface 6-1 matched with the inner ring of the bearing 5; as shown in fig. 4 and 5, the spring 7 is located in the radial sliding chute 1-1, one end of the spring 7 abuts against the bottom end of the radial sliding chute 1-1, and the other end of the spring 7 abuts against the other end of the pressure plate 6; the spring 7 is a compression spring. The pressure sensor 3 is arranged in a radial sliding groove 1-1 of the belt pulley shaft 1, one end of the pressure sensor 3 is abutted against the bottom end of the radial sliding groove 1-1, and the other end of the pressure sensor 3 is in contact with or separated from the other end of the pressure plate 6. As shown in fig. 2 to 4, the tensioner pulley 2 is fitted around the outer periphery of the bearing 5; when the tension belt 51 is in a tensioned state, the other end of the pressure sensor 3 is in contact with the other end of the platen 6; when the tension belt 51 is in a slack state, the pressure plate 6 is moved radially outward by the spring 7, and the other end of the pressure sensor 3 is separated from the other end of the pressure plate 6. As shown in fig. 7, the pressure sensor 3, the motor driver 16 and the sensor 13 are all electrically connected or wirelessly connected with the main controller 4; the tensioning motor 9 is electrically connected or wirelessly communicated with a motor driver 16; when the pressure value of the pressure sensor 3 is equal to 0, the main controller 4 controls the output shaft of the tensioning motor 9 to start rotating through the motor driver 16; when the rotation speed value of the sensor 13 is smaller than the set rotation speed value in the main controller 4, the output shaft of the tension motor 9 is controlled by the main controller 4 through the motor driver 16 to stop rotating. Since the pressure plate 6 moves radially outward under the action of the spring 7 when the tension belt 51 is in a loose state, the other end of the pressure sensor 3 is separated from the other end of the pressure plate 6, the tension force on the pressure plate 6 cannot be transmitted to the pressure sensor 3, the pressure value of the pressure sensor 3 is equal to 0, and the main controller 4 controls the output shaft of the tension motor 9 to start rotating. The set rotation speed value in the main controller 4 is the rotation speed of the output shaft of the tension motor 9 detected by the sensor 13 when the tension belt 51 is in the tension state by the test. When the rotation speed value of the sensor 13 is smaller than the set rotation speed value in the main controller 4, the tension belt 51 is already in the tension state.

As shown in fig. 1, further includes a sensor holder 17; the sensor 13 is fixedly connected to the body of the tensioning motor 9 by a sensor bracket 17. In this embodiment, the sensor 13 is fixedly connected to the sensor bracket 17 through a fastener, and the sensor bracket 17 is fixedly connected to the body of the tension motor 9 through a fastener.

Also includes a coupling 18; the output shaft of the tensioning motor 9 is in transmission connection with one end of the worm 10 through a coupling 18. The coupling 18 is positioned axially with the output shaft of the tensioning motor 9 and one end 10 of the worm by means of a set screw.

When the fixing frame 14 is used, the fixing frame is fixedly connected to a frame of an electric automobile through a fastener. As shown in fig. 8, the tension belt 51 is wound around the outer peripheral surfaces of the drive pulley 55 of the drive motor of the electric vehicle, the first driven pulley 56 of the cooling water pump, the second driven pulley 57 of the steering oil pump, the third driven pulley 58 of the air compressor, and the tension pulley 2 of the present invention, and the pressure sensor 3 is located on the bisector of the wrap angle formed by the tension belt 51 and the tension pulley 2.

The working principle of the invention is as follows: as shown in fig. 1 to 8, the pulley shaft 1 is provided with a radial sliding groove 1-1; the bearing 5 is sleeved on the periphery of the belt pulley shaft 1, and a clearance fit is formed between the inner ring of the bearing 5 and the periphery of the support shaft 15; the pressure plate 6 is connected in the radial sliding groove 1-1 in a sliding manner, and the pressure plate 6 is provided with an arc surface 6-1 matched with the inner ring of the bearing 5; the tensioning belt pulley 2 is sleeved on the periphery of the bearing 5; also, since the present invention is used by winding the tension belt 51 around the outer circumferential surfaces of the drive pulley 55 of the drive motor of the electric vehicle, the first driven pulley 56 of the cooling water pump, the second driven pulley 57 of the steering oil pump, the third driven pulley 58 of the air compressor, and the tension pulley 2 of the present invention, and by positioning the pressure sensor 3 on the bisector of the angle formed by the tension belt 51 and the tension pulley 2, when the tension belt 51 is in a tensioned state, the preload of the tension belt 51 can be transmitted to the bearing 5 through the tension pulley 2, and then transmitted to the pressure plate 6 through the bearing 5, and the spring 7 is in a compressed state through the other end of the pressure plate 6, and when the other end of the pressure sensor 3 is in contact with the other end of the pressure plate 6, the tension is transmitted to the pressure sensor 3 by the pressure plate 6. When the tension belt 51 is loosened, the pressure plate 6 moves outwards in the radial direction under the action of the spring 7, the other end of the pressure sensor 3 is separated from the other end of the pressure plate 6, at this time, the pressure value of the pressure sensor 3 is equal to 0, when the pressure value of the pressure sensor 3 is equal to 0, the main controller 4 controls the output shaft of the tension motor 9 to start rotating through the motor driver 16, the worm 10 rotates synchronously with the output shaft of the tension motor 9, because the other end of the worm 10 is in transmission connection with the worm wheel 11, the worm 10 rotates to drive the worm wheel 11 to rotate clockwise, and because the worm wheel 11 is fixedly connected to one end of the tension bracket 8 and the worm wheel 11 is coaxially arranged with the bracket shaft 15, one end of the tension bracket 8 is rotatably connected to the bracket shaft 15, and therefore, the worm wheel 11 can drive the tension bracket 8. The pulley shaft 1 is fixedly connected to the other end of the tensioning bracket 8; the bearing 5 is sleeved on the periphery of the belt pulley shaft 1, and an inner ring of the bearing 5 is in clearance fit with the periphery of the belt pulley shaft 1; the tensioning belt pulley 2 is sleeved on the periphery of the bearing 5; therefore, when the tension bracket 8 rotates clockwise around the axis of the bracket shaft 15, the pulley shaft 1 fixedly connected to the other end of the tension bracket 8 also rotates clockwise around the axis of the bracket shaft 15, so that the bearing 5 provided on the outer periphery of the pulley shaft 1 and the tension pulley 2 fitted around the outer periphery of the bearing 5 also rotate clockwise around the axis of the bracket shaft 15, and at this time, the tension pulley 2 moves to the lower right, so that the tension belt 51 is automatically tensioned, that is, the invention can automatically tension the tension belt 51 after being loosened.

When the tension belt 51 is tensioned, the resistance of the tension bracket 8 rotating clockwise around the axis of the bracket shaft 15 is increased, and the resistance of the worm wheel 11 rotating clockwise is also increased, so that the rotation speed of the output shaft of the tension motor 9 and the worm 10 is reduced, when the rotating speed value of the sensor 13 is smaller than the set rotating speed value in the main controller 4, the output shaft of the tensioning motor 9 is controlled by the main controller 4 through the motor driver 16 to stop rotating, at this time, the worm 10 does not rotate any more, the worm wheel 11 in transmission connection with the worm 10 does not rotate any more, the worm wheel 11 does not drive the tensioning bracket 8 to synchronously rotate clockwise around the axis of the bracket shaft 15 any more, and the tensioning belt pulley 2 does not rotate clockwise around the axis of the bracket shaft 15 any more, so that the tensioning belt pulley 2 does not move to the lower right any more, the tensioning process of the tensioning belt 51 is finished, the tensioning force of the tensioning belt 51 is not increased any more, and the tensioning force can be automatically controlled.