JP6254488B2 - Bicycle with electric motor - Google Patents

Description

  The present invention relates to a bicycle with an electric motor.

  Bicycles with electric motors such as so-called electric assist bicycles are provided with a motor that generates an auxiliary driving force. As a motor control method, for example, the following has been proposed.

  Patent Document 1 describes a bicycle with an electric motor in which a human power drive system and an electric drive system are provided in parallel, and the output of the electric drive system is controlled in response to changes in the driving force due to human power. The electric motor-equipped bicycle includes a pedaling force detection unit that detects a pedaling force, a vehicle speed detection unit that detects a vehicle speed, a pedaling force reference value determination unit that determines a reference value that increases or decreases in response to an increase or decrease in the vehicle speed, and a pedaling force that is a reference value. Comparing means for comparison and motor driving force calculating means for setting the driving force to be output by the electric drive system to zero when the pedaling force is smaller than the reference value are provided.

  Patent Document 2 describes a battery-assisted bicycle that uses the power of a motor to assist in manual driving. This battery-assisted bicycle has a pedaling force detecting means for detecting a pedaling force, an assist determining means for determining the start of an assist when the pedaling force exceeds a predetermined reference value, and a driving state according to the pedaling force. Operating state determining means for determining. The driving state determination means detects that the state where the detected pedaling force is equal to or less than a predetermined determination value has continued for a predetermined determination time, and determines that the vehicle is not being driven. The assist determination means increases the predetermined reference value when it is detected that the vehicle is not being driven.

JP-A-5-246378 JP-A-8-58669

  2. Description of the Related Art A belt drive type bicycle using a belt is known instead of a conventional chain that transmits a pedaling force applied to a pedal to a wheel. According to the belt drive type bicycle, no lubrication is required, and no sagging due to elongation due to wear does not occur like a chain, so that maintenance is not required. Furthermore, there is an advantage that the operation sound is quieter than that of the chain drive.

  As a belt used in the belt drive system, a belt using a kevlar (aramid fiber) as a core wire is known. With this type of belt, the belt stretches slightly when the pedal is depressed, giving a soft ride. On the other hand, in recent years, carbon belts using carbon fibers suitable for sports applications that require more direct response to pedaling force have been put into practical use. Carbon fiber has a higher strength and elastic modulus than iron, and is excellent in wear resistance, heat resistance, thermal stretchability, and the like. According to the carbon belt, the elongation is small as compared with a belt using Kevlar or the like as a core, and response performance comparable to that of a conventional chain can be obtained without using a tension adjusting mechanism.

  The present inventors have discovered that the following problems occur in a belt drive type electric bicycle. In a general bicycle with an electric motor, a torque sensor is attached to a crankshaft connected to a pedal via a crank, and an auxiliary driving force corresponding to the magnitude of the torque detected by the torque sensor is provided by the motor. generate. In a belt drive type bicycle, the width of the pulley on which the belt is mounted corresponds to the width of the belt, and is wider than the sprocket width in the conventional chain drive method. For this reason, foreign matters such as stones, leaves, dust, and snow are easily caught between the belt and the pulley. When foreign matter is sandwiched between the belt and the pulley, the belt tension increases. When the belt tension increases, torque is generated on the crankshaft even when no pedal force is applied to the pedal. Thereby, the torque sensor attached to the crankshaft may detect the torque. That is, the torque sensor detects the input torque generated in the crankshaft when foreign matter is sandwiched between the belt and the pulley in the same manner as the input torque generated in the crankshaft by applying the pedaling force to the pedal during normal traveling. As a result, the motor generates an auxiliary driving force in a state where no pedaling force is applied to the pedal. That is, there is a possibility that an auxiliary driving force unintended by the user is generated. In addition, the motor is driven even when the vehicle is stopped, and there is a risk that power is wasted. In particular, in a belt drive system using a carbon belt, an increase in belt tension due to the inclusion of foreign matter is remarkable, and the above-described problem is likely to be manifested. To solve this problem, for example, when the input torque is below a predetermined value, a measure to stop the auxiliary driving force by the motor can be considered, but when the range of the input torque to stop the auxiliary driving force is simply determined. The auxiliary driving force that is originally required cannot be obtained, and the ride comfort during travel may be impaired.

  The present invention has been made in view of the above-described points, and prevents the motor from operating in accordance with the input torque generated due to the situation where the pedaling force is not applied while maintaining the riding comfort during traveling. An object of the present invention is to provide a bicycle with an electric motor.

According to a first aspect of the present invention, a vehicle speed detection unit that detects a vehicle speed, a torque detection unit that detects an input torque generated in a crankshaft connected to the pedal by a pedaling force applied to the pedal, and the crankshaft A drive pulley that rotates with the rear wheel, a driven pulley that rotates with the rear wheel, and an endless belt wound around the drive pulley and the driven pulley, and that transmits the input torque generated on the crankshaft to the rear wheel A motor that generates auxiliary driving force for driving the front wheel or the rear wheel, and an assist ratio that is a ratio of the auxiliary driving force to the magnitude of the input torque detected by the torque detector is associated with the vehicle speed and the input torque. On the basis of the assist ratio map, the vehicle speed detected by the vehicle speed detection unit is smaller than the first vehicle speed and When the input torque detected by the torque detector is in a low-speed and low-torque state that is smaller than the first torque of a magnitude that can be generated in the crankshaft when a foreign object is sandwiched between the belt and the driven pulley. In addition, when the motor is controlled so that the assist ratio becomes zero and the vehicle speed detected by the vehicle speed detection unit exceeds the second vehicle speed that is higher than the first vehicle speed, the torque detection unit detects the vehicle speed. Regardless of the magnitude of the input torque, the assist ratio is gradually decreased to zero as the vehicle speed increases, and the vehicle speed exceeds a third vehicle speed greater than the second vehicle speed at which the assist ratio reaches zero. The motor is controlled to maintain the assist ratio at zero, the vehicle speed detected by the vehicle speed detection unit is smaller than the first vehicle speed, and the When the input torque detected by the torque detector is larger than the first torque, the assist ratio is increased to a maximum value according to the increase of the input torque, and the assist ratio reaches the maximum value. The motor is controlled to maintain the assist ratio at the maximum value with respect to an input torque exceeding a second torque larger than a torque of 1, and the input torque detected by the torque detector is the first torque. When the vehicle speed detected by the vehicle speed detector is smaller than the torque and greater than the first vehicle speed and less than or equal to the second vehicle speed, the assist ratio is increased to the maximum value as the vehicle speed increases. The assist ratio is maintained at the maximum value for a vehicle speed exceeding a fourth vehicle speed that is smaller than the second vehicle speed at which the assist ratio reaches the maximum value. The motor is controlled, the input torque detected by the torque detector is greater than the second torque, the vehicle speed detected by the vehicle speed detector is greater than the first vehicle speed, and the second And the input torque detected by the torque detector is larger than the first torque and smaller than the second torque, and the vehicle speed detected by the vehicle speed detector is the first speed. And a control unit that controls the motor so that the assist ratio becomes the maximum value when the vehicle speed is greater than 4 and less than or equal to the second vehicle speed .

According to a second aspect of the invention, the belt, bicycles motor with the first aspect, which is configured to include a core wire made of carbon fibers is provided.

According to a third aspect of the present invention, there is provided the electric bicycle according to the first or second aspect , wherein the torque detection unit includes a magnetostrictive torque sensor.

  ADVANTAGE OF THE INVENTION According to this invention, the bicycle with an electric motor which can prevent that a motor act | operates according to the input torque which arises from the condition where pedaling force is not applied, maintaining riding comfort at the time of driving | running | working is provided. It becomes possible.

1 is a side view of a bicycle with an electric motor according to an embodiment of the present invention. It is a figure which shows the structure of the belt which concerns on embodiment of this invention. It is a block diagram which shows the electric constitution of the bicycle with an electric motor which concerns on embodiment of this invention. It is a figure which shows the structure of the torque sensor which concerns on embodiment of this invention. It is a figure which shows the connection relation of the battery which concerns on embodiment of this invention, a motor drive circuit, and a motor in detail. It is a figure which shows the drive part in the bicycle with an electric motor which concerns on embodiment of this invention. It is a figure which shows the assist ratio map which concerns on embodiment of this invention. It is a flowchart which shows the flow of the process in which the arithmetic processing part which concerns on this embodiment calculates a motor drive command value. It is a figure which shows the relationship between the input torque and auxiliary | assistant drive force in the bicycle with an electric motor which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a side view of an electric bicycle 1 according to an embodiment of the present invention. The bicycle 1 with an electric motor has a frame including a front fork 11, a head pipe 12, a down tube 13, a seat tube 14, a seat stay 15, and a chain stay 16. The front wheel 17 is rotatably attached to the front fork 11, and the rear wheel 18 is rotatably attached to a rotating shaft 19 that is an intersection of the seat stay 15 and the chain stay 16. A handle stem 20 is rotatably inserted into the head pipe 12, and a handle 21 is attached to the upper end of the handle stem 20. On the other hand, a seat post 22 is fitted to the seat tube 14, and a saddle 23 is attached to the upper end of the seat post 22. A crankshaft 24 is supported at one end of the chain stay 16, and a crank 25 is attached to the crankshaft 24. A pedal 26 is rotatably supported at the tip of the crank 25. A drive pulley 27 that rotates integrally with the crankshaft 24 is attached to the crankshaft 24. A driven pulley 28 is attached to the other end of the chain stay 16. The driven pulley 28 is supported by the rotating shaft 19 of the rear wheel 18 and rotates integrally with the rear wheel 18.

  An endless belt 30 is wound around the driving pulley 27 and the driven pulley 28. A plurality of teeth 31 (see FIG. 2) are formed on the inner peripheral surface of the belt 30, and these teeth are a plurality of teeth (not shown) formed on the peripheral surfaces of the drive pulley 27 and the driven pulley 28. ). When the crank 25 is rotated in the direction of arrow A (clockwise) by applying a pedaling force to the pedal 26, the drive pulley 27 rotates in the direction of arrow B (clockwise) together with the crankshaft 24, and the belt 30 rotates in the direction of arrow C. Moving. The driven pulley 28 is rotated by the circumferential movement of the belt 30, and power is transmitted to the rear wheel 18. As described above, the electric bicycle 1 according to the present embodiment includes the belt drive mechanism including the drive pulley 27, the driven pulley 28, and the belt 30.

  The motor 40 is mounted on the rotary shaft 29 of the front wheel 17 and generates an auxiliary driving force that drives the front wheel 17. That is, the electric bicycle 1 is a hub mount type in which the motor is mounted on the front wheel hub. The rotation of the motor 40 is decelerated by a reduction mechanism (not shown) and transmitted to the front wheels 17. The motor 40 can be constituted by, for example, a brushless DC motor.

  Electric power for driving the motor 40 is supplied from a battery 41 detachably provided along the seat tube 14. The battery 41 is composed of, for example, a lithium ion secondary battery, and can be repeatedly used by charging. Note that the battery may be attached at a location other than the seat tube. For example, the battery 41 may be attached to the down tube 13.

  FIG. 2 is a view showing the internal structure of the belt 30. The belt 30 has a plurality of teeth 31 on the inner peripheral surface. The belt 30 is made of, for example, a resin material mainly composed of polyurethane, and a plurality of core wires 32 extending in the extending direction of the belt 30 are embedded in the polyurethane. The core wire 32 is made of carbon fiber. Carbon fiber has a higher elastic modulus than Kevlar conventionally used as a core wire. By using carbon fiber as the core of the belt 30, the elongation can be reduced compared to a belt using Kevlar or the like as the core, and response performance comparable to that of a conventional chain without using a tension adjustment mechanism. Can be obtained. In the belt 30, a reinforcing cloth 33 made of, for example, nylon fiber is embedded in the vicinity of the root of the tooth 31.

FIG. 3 is a block diagram showing an electrical configuration of the electric bicycle 1. The vehicle speed sensor 112 detects a running speed of a bicycle with an electric motor 1 (vehicle speed), and outputs a vehicle speed detection signal S _V indicating the detected vehicle speed. Vehicle speed detection signal S _V outputted from the vehicle speed sensor 112 are supplied to the arithmetic processing unit 116. The vehicle speed sensor 112 is known to be outputted for example, a plurality of magnet pieces arranged along the circumferential direction of the rotary shaft 29 of the front wheel 17, a pulse signal having a period corresponding to the rotational speed of the front wheel 17 as a vehicle speed detection signal S _V It is possible to use a vehicle speed sensor.

The torque sensor 114 detects the magnitude of the torque generated in the crankshaft 24 by the depression force is applied to the pedal 26, and outputs a torque detection signal S _T that indicates the magnitude of the detected torque. Torque detection signal S _T output from the torque sensor 114 is supplied to the arithmetic processing unit 116.

  FIG. 4 is a diagram illustrating a configuration of the torque sensor 114. As the torque sensor 114, a magnetostrictive torque sensor using the magnetostrictive effect can be suitably used. The torque sensor 114 has a magnetostrictive material 201 attached to the crankshaft 24. The magnetostrictive material 201 includes detection units 202A and 202B arranged along the axial direction of the crankshaft 24. The detection units 202A and 202B have a plurality of grooves (not shown) for promoting the magnetostrictive effect. In addition, since the magnetostrictive torque sensor is well-known, description about specific structures, such as said groove shape and inclination, is abbreviate | omitted. In the vicinity of the detection units 202A and 202B, detection coils 203A and 203B are provided correspondingly. The detection coils 203A and 203B are not in contact with the magnetostrictive material 201.

Torque generated in the crankshaft 24 when a pedaling force is applied to the pedal 26 is transmitted to the magnetostrictive material 201, and the magnetic permeability of the magnetostrictive material 201 changes due to the inverse magnetostrictive effect. Since the torque acting on the magnetostrictive material 201 differs between the detection units 202A and 202B, there is a difference in magnetic permeability between the detection units 202A and 202B. As a result, a difference occurs in the induced electromotive force induced in the detection coils 203A and 203B. The magnitude of the induced electromotive force difference between the detection coils 203A and 203B corresponds to the magnitude of the torque applied to the crankshaft 24. The torque sensor 114 outputs an electrical signal corresponding to the difference between the induced electromotive force between the detection coil 203A and 203B, as a torque detection signal S _T that indicates the magnitude of the torque applied to the crankshaft 24 (input torque) To do.

  The arithmetic processing unit 116 includes an LSI (Large Scale Integration) integrated with a computer system. The arithmetic processing unit 116 includes a memory 118. The memory 118 stores an assist ratio map. The arithmetic processing unit 116 performs drive control of the motor 40 based on the assist ratio map. The arithmetic processing unit 116 calculates a target value of auxiliary driving force (motor output torque) to be generated by the motor 40 based on the assist ratio map stored in the memory 118. The arithmetic processing unit 116 supplies the motor drive circuit 120 with a motor drive command value C indicating the calculated target value of the auxiliary drive force (motor output torque). Details of the assist ratio map will be described later.

  The motor drive circuit 120 extracts drive power having a magnitude corresponding to the target value of the auxiliary drive force (motor output torque) indicated by the motor drive command value C supplied from the arithmetic processing unit 116 from the battery 41 to the motor 40. Supply.

  FIG. 5 is a diagram showing in detail the connection relationship between the battery 41, the motor drive circuit 120, and the motor 40. The motor driving circuit 120 includes an inverter circuit 121 including transistors Q1 to Q6, an inverter control circuit 122 that generates gate signals for individually turning on and off the transistors Q1 to Q6, and a current in a direction from the battery 41 to the motor 40. And a diode D that cuts off current in a direction from the motor 40 toward the battery 41.

  Each of the transistors Q1 to Q6 is composed of an n-channel MOSFET having a diode having a cathode connected to the drain side and an anode connected to the source side. The transistors Q1 to Q6 can pass a current in the reverse direction via the diode even in the off state. In the present embodiment, the motor 40 is an inner rotor type brushless motor, and includes a rotor including a permanent magnet, a stator having a motor winding L, three Hall elements H for detecting the rotational position of the rotor, Is included. Connection points u, v, transistors Q1, Q3, Q5 connected to the positive side (high side) of the battery 41 and transistors Q2, Q4, Q6 connected to the negative side (low side) of the battery 41, w is connected to each of the three motor windings L constituting the motor 40.

  The inverter control circuit 122 detects the angular position of the rotor based on the detection signals output from the three Hall elements H, and supplies the control signals G1 to G6 to the gates of the transistors Q1 to Q6 according to the detected angular position of the rotor. Thus, the transistors Q1 to Q6 are turned on in a certain order. As a result, the direction of the current flowing through the motor winding L is sequentially switched to rotate the rotor. The inverter control circuit 122 adjusts the on-duty of the transistors Q1 to Q6 based on the target value of the auxiliary driving force (motor output torque) indicated by the motor drive command value C supplied from the arithmetic processing unit 116.

  The vehicle speed sensor 112 is an example of a vehicle speed detection unit in the present invention. The torque sensor 114 is an example of a torque detector in the present invention. The arithmetic processing unit 116 and the motor drive circuit 120 are an example of a control unit in the present invention. The motor 40 is an example of a motor in the present invention.

  In the electric bicycle 1 according to this embodiment, as shown in FIG. 6, when a foreign object X is sandwiched between the driven pulley 28 and the belt 30, tension acts on the belt 30 in the direction of arrow E. . In particular, the belt 30 is a carbon belt having high elasticity and hardly stretches, so that an increase in tension due to the inclusion of foreign matter becomes significant. When the tension is applied to the belt 30, a rotational force acts on the drive pulley 27 in the direction of arrow F (counterclockwise), and torque is generated on the crankshaft 24. Torque generated on the crankshaft 24 is detected by a torque sensor 114 provided on the crankshaft 24. In particular, since the torque sensor 114 is a magnetostrictive torque sensor, the responsiveness in the low torque region is higher than that of the mechanical torque sensor, and a relatively small torque generated in the crankshaft 24 as the tension of the belt 30 increases. Can also be detected.

  The arithmetic processing unit 116 performs drive control of the motor 40 so that the motor 40 generates an auxiliary driving force having a magnitude corresponding to the magnitude of the input torque detected by the torque sensor 114. Therefore, even when the pedaling force is not applied to the pedal 26 as described above, when the input torque is generated on the crankshaft 24, the motor 40 is operated accordingly. The operation of the motor in a state where no pedal force is applied to the pedal 26 is not preferable because it not only causes generation of an auxiliary driving force that is not intended by the user but also wastes power. In particular, as in the bicycle 1 with an electric motor according to the present embodiment, when the carbon belt and the magnetostrictive torque sensor are provided, the above problem is likely to be manifested. In the bicycle 1 with an electric motor according to the present embodiment, the above problem is addressed by constructing the assist ratio map stored in the memory 118 as follows.

  FIG. 7 is a diagram illustrating an example of the assist ratio map according to the present embodiment. The assist ratio map is stored in the memory 118. The assist ratio map according to the present embodiment is a three-dimensional map in which the assist ratio is associated with the vehicle speed and the input torque.

In the assist ratio map according to the present embodiment, the assist is performed in a low speed and low torque state where the vehicle speed V is V ₁ or less (0 ≦ V ≦ V ₁ ) and the input torque T is T ₁ or less (0 ≦ T ≦ T ₁ ). The ratio is set to zero.

As the upper limit vehicle speed V ₁ to which the assist ratio 0 is applied, for example, a speed sufficiently lower than the vehicle speed during normal travel (for example, about 10 km / h) is preferably applied. Further, as the input torque T ₁ of the upper applying the assist ratio 0, for example, occur in the crank shaft 24 in such a case where foreign matter is sandwiched, no depression force is applied status between the belt 30 and the driven pulley 28 It is preferably a value corresponding to the magnitude of the input torque to be obtained and sufficiently smaller than the input torque corresponding to the pedaling force at low speed. In a low speed range where the vehicle speed V is V ₁ or less, a relatively large pedaling force is applied to the pedal 26, and the input torque generated on the crankshaft 24 is assumed to be a relatively large value (about several tens of N / m). . Therefore, it is possible to set as _{T 1,} a relatively large value (e.g. 15N / m).

Further, according to the assist ratio map according to the present embodiment, the assist ratio in a case other than the low speed low torque state is set to a value larger than 0 within a predetermined vehicle speed range (V ≦ V ₃ ). That is, the assist ratio is set to a value larger than 0 in the region where the input torque T is larger than T ₁ even when the vehicle speed V is V ₁ or less. Further, in the region where the vehicle speed V is V ₂ or more, which is larger than V ₁ , the assist ratio decreases linearly with the increase in the vehicle speed, and becomes 0 when the vehicle speed V becomes V ₃ (V ₃ > V ₂ ). Is set to

  FIG. 8 is a flowchart showing a flow of processing in which the arithmetic processing unit 116 calculates the motor drive command value C based on the assist ratio map.

Processing unit 116 in step S1 refers to the vehicle speed V indicated by the vehicle speed detection signal S _V outputted from the vehicle speed sensor 112.

Processing unit 116 in step S2 to see an input torque T indicated by the torque detection signal S _T output from the torque sensor 114.

In step S3, the arithmetic processing unit 116 derives the assist ratio R corresponding to the vehicle speed V and the input torque T referred to in steps S1 and S2 by referring to the assist ratio map stored in the memory 118. Note that the vehicle speed V referred to in step S1 is V ₁ or less (0 ≦ V ≦ V ₁ ) and the input torque T referred to in step S2 is T ₁ or less (0 ≦ T ≦ T ₁ ) (low speed low In the case of a torque state), 0 is derived as the assist ratio R based on the assist ratio map.

  In step S4, the arithmetic processing unit 116 calculates R × T for the assist ratio R derived in step S3 and the input torque T referred to in step S2, thereby obtaining the target value α (α = R × T) of the auxiliary driving force. Is calculated.

  In step S5, the arithmetic processing unit 116 calculates a motor drive command value C by performing a predetermined conversion process on the target value α of the auxiliary driving force calculated in step S4, and ends this routine.

FIG. 9 is a diagram showing the relationship between the input torque and the auxiliary driving force (motor output torque) in the electric bicycle 1 according to the present embodiment. In FIG. 9, the solid line corresponds to the case of the vehicle speed Va (0 <Va <V ₁ ), and the broken line corresponds to the case of the vehicle speed Vb (V ₂ <Vb <V ₃ ).

As described above, the arithmetic processing unit 116 calculates the target value α of the auxiliary driving force (motor output torque) generated by the motor 40 based on the assist ratio map shown in FIG. Therefore, in the case of the vehicle speed Va (0 <Va <V ₁ ), as shown by the solid line in FIG. 9, the auxiliary driving force (motor output torque) is 0 in the region where the input torque is 0 or more and T ₁ or less. . On the other hand, in a region where input torque exceeds T _1, the auxiliary driving force (motor output torque), 0 a magnitude greater than that corresponding to the magnitude of the input torque. On the other hand, in the case of the vehicle speed Vb (V ₂ <Vb <V ₃ ), as shown by the broken line in FIG. 9, the auxiliary driving force (motor output torque) is 0 in accordance with the magnitude of the input torque in the entire region. It becomes bigger than.

As described above, in the assist ratio map according to the present embodiment, is set in the assist ratio when vehicle speed is and the input torque is equal to or less than a predetermined value V ₁ of the low-speed low-torque state is less than the predetermined value T ₁ is 0 Yes. Accordingly, the arithmetic processing unit 116 controls the motor 40 so as to stop the generation of the auxiliary driving force in the low speed and low torque state. As a result, for example, the motor 40 is operated in accordance with the input torque generated in the crankshaft 24 due to a situation in which no treading force is applied, such as when a foreign object is sandwiched between the belt 30 and the driven pulley 28. Can be prevented. Thereby, the generation of the auxiliary driving force in a situation where the auxiliary driving force by the motor 40 is not required, that is, a situation not intended by the user can be prevented. Moreover, it is possible to avoid wasteful consumption of electric power. In the assist ratio map according to the present embodiment, the assist ratio in a case other than the low speed and low torque state is set to a value larger than zero. Therefore, the arithmetic processing unit 116 controls the motor 40 so as to generate the auxiliary driving force in cases other than the low speed and low torque state. Thus, by generating the auxiliary driving force during normal running other than the low speed and low torque state, the user can be prevented from feeling insufficient assistance.

  As described above, according to the electric bicycle 1 according to the present embodiment, since the generation of the auxiliary driving force is stopped in the low speed and low torque state, the pedaling force is not applied while maintaining the riding comfort during traveling. It is possible to prevent the motor from operating according to the input torque generated due to the situation.

  In this embodiment, the case where the present invention is applied to a hub-mounted electric bicycle with a motor mounted on the front wheel hub is illustrated. However, the motor is provided in the vicinity of the pedal, and the output of the motor is transmitted to the rear wheel. It is also possible to apply the present invention to a center-mounted bicycle with an electric motor.

  Further, in this embodiment, the case where a carbon belt having a core made of carbon fiber is applied is exemplified, but the present invention is not limited to this, and a belt drive mechanism using a belt other than the carbon belt is provided. The present invention can also be applied to a bicycle with an electric motor.

DESCRIPTION OF SYMBOLS 1 Bicycle 17 with an electric motor Front wheel 18 Rear wheel 24 Crankshaft 27 Drive pulley 28 Driven pulley 30 Belt 40 Motor 112 Vehicle speed sensor 114 Torque sensor 116 Operation processing part 118 Memory 120 Motor drive circuit

Claims (3)

A vehicle speed detector for detecting the vehicle speed;
A torque detector for detecting an input torque generated in a crankshaft connected to the pedal by a pedaling force applied to the pedal;
A drive pulley that rotates with the crankshaft, a driven pulley that rotates with a rear wheel, and an endless belt wound around the drive pulley and the driven pulley, and transmits input torque generated on the crankshaft to the rear wheel A drive mechanism to
A motor for generating an auxiliary driving force for driving a front wheel or the rear wheel;
Based on an assist ratio map in which an assist ratio, which is a ratio of the auxiliary driving force to the magnitude of the input torque detected by the torque detector, is associated with the vehicle speed and the input torque, the vehicle speed detected by the vehicle speed detector is the first. The input torque detected by the torque detector is smaller than the first vehicle speed and is larger than the first torque that can be generated in the crankshaft when a foreign object is sandwiched between the belt and the driven pulley. When the motor is controlled so that the assist ratio becomes zero in the case of a small low speed and low torque state, and the vehicle speed detected by the vehicle speed detection unit exceeds a second vehicle speed greater than the first vehicle speed. Regardless of the magnitude of the input torque detected by the torque detector, the assist ratio is gradually reduced to zero as the vehicle speed increases. And the motor is controlled to maintain the assist ratio at zero with respect to a vehicle speed exceeding a third vehicle speed greater than the second vehicle speed at which the assist ratio reaches zero, and is detected by the vehicle speed detecting unit. When the vehicle speed is smaller than the first vehicle speed and the input torque detected by the torque detector is larger than the first torque, the assist ratio is increased to the maximum value according to the increase of the input torque. Controlling the motor to maintain the assist ratio at the maximum value for an input torque exceeding a second torque that is greater than the first torque at which the assist ratio reaches the maximum value, The input torque detected by the torque detector is smaller than the first torque, and the vehicle speed detected by the vehicle speed detector is larger than the first vehicle speed. When the vehicle speed is less than or equal to the second vehicle speed, the assist ratio is increased to the maximum value in accordance with an increase in the vehicle speed, and the assist ratio reaches the maximum value, and the fourth vehicle speed is smaller than the second vehicle speed. The motor is controlled so as to maintain the assist ratio at the maximum value for a vehicle speed exceeding 1, an input torque detected by the torque detector is larger than the second torque, and the vehicle speed detector When the detected vehicle speed is greater than the first vehicle speed and less than or equal to the second vehicle speed, and when the input torque detected by the torque detector is greater than the first torque and the second vehicle speed When the vehicle speed detected by the vehicle speed detection unit is smaller than the torque and greater than the fourth vehicle speed and less than or equal to the second vehicle speed, the assist ratio becomes the maximum value. A control unit for controlling the motor ;
Including electric bicycle. The bicycle with an electric motor according to claim 1, wherein the belt includes a core wire made of carbon fiber. The bicycle with an electric motor according to claim 1, wherein the torque detector includes a magnetostrictive torque sensor.