Motor system

Abstract

This system provides a motor that can assist the driving of human-powered vehicles with simple control. [Solution] The motor system is a system for assisting the driving of a human-powered vehicle, which has a first wheel, a second wheel, and an input unit to which human power output for driving the second wheel is input, and comprises a motor that drives the human-powered vehicle with a predetermined output, and a motor control device that controls the driving of the motor. The motor control device determines the assist output of the motor system based on the human power output, stops the motor when the assist output is less than the predetermined output, and drives the motor when the assist output is equal to or greater than the predetermined output.

Description

Technical Field

[0001] The present invention relates to a motor system.

Background Art

[0002] In recent years, efforts have been made to promote the Sustainable Development Goals (SDGs, the 2030 Agenda for Sustainable Development, adopted at the United Nations Summit on September 25, 2015 (hereinafter referred to as "SDGs")). Along with this, technologies for reducing waste and defective products, etc. are known in order to ensure sustainable production and consumption patterns.

[0003] Conventionally, technologies for adjusting the power of each of a first motor for assisting the rotation of a front wheel and a second motor for assisting the rotation of a rear wheel based on a human driving force are known (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the technology of Patent Document 1, since it is necessary to dynamically control the power of each motor according to the human driving force, there are problems that a high-performance microcomputer and FET (Field Effect Transistor) are required and the calculation load is large.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a motor system capable of assisting the driving of a human-powered vehicle with simple control.

Means for Solving the Problems

[0007] To achieve the above objective, the present invention provides a motor system for assisting the driving of a human-powered vehicle comprising a first wheel, a second wheel, and an input unit to which human power output for driving the second wheel is input, wherein the system comprises a motor that drives the human-powered vehicle with a predetermined output and a motor control device that controls the driving of the motor, the motor control device determines the assist output of the motor system based on the human power output, stops the motor when the assist output is less than the predetermined output, and drives the motor when the assist output is equal to or greater than the predetermined output. [Effects of the Invention]

[0008] According to the present invention, a motor system capable of assisting the driving of a human-powered vehicle can be obtained with simple control. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments. [Brief explanation of the drawing]

[0009] [Figure 1] This is a side view of an electric assist bicycle according to this embodiment. [Figure 2] This is a block diagram of the motor system according to this embodiment. [Figure 3] This is a flowchart of the motor control process. [Figure 4] This figure shows an example of the relationship between vehicle speed and assist ratio. [Figure 5] This figure shows an example of the relationship between assist output and the status of each motor. [Figure 6] This figure shows another example of the relationship between assist output and the state of each motor. [Figure 7] This figure shows yet another example of the relationship between assist output and the state of each motor. [Modes for carrying out the invention]

[0010] [Configuration of Electric Assist Bicycle 1] Figure 1 is a side view of the electric assist bicycle 1 according to this embodiment. Figure 2 is a block diagram of the motor system 100 according to this embodiment. Hereinafter, assuming that the electric assist bicycle 1 is placed on a horizontal surface, the direction perpendicular to the mounting surface will be referred to as the "up and down direction", the direction including the direction of travel of the electric assist bicycle 1 will be referred to as the "front and back direction", and the direction perpendicular to the up and down direction and the front and back direction will be referred to as the "left and right direction".

[0011] The electric assist bicycle 1 is an example of an electric assist vehicle that uses an electric motor to assist the force applied by the user (hereinafter simply referred to as "user") to pedal 23L and 23R, thereby rotating the front wheel 7F and rear wheel 7B (i.e., driving the electric assist bicycle 1). As shown in Figures 1 and 2, the electric assist bicycle 1 consists of a main body 2 and a motor system 100. The main body 2 is an example of a human-powered vehicle.

[0012] The main body 2 is a bicycle whose propulsion is assisted by the motor system 100. The main body 2 may be an existing bicycle that has been repurposed, or it may be newly designed to accommodate the motor system 100. As shown in Figure 1, the main body 2 mainly comprises a frame 3, a front fork 4, a saddle 5, handlebars 6, a front wheel 7F and a rear wheel 7B (hereinafter, these may be collectively referred to as "wheels 7"), a steering column 8, a pedaling force transmission mechanism 20, and a brake mechanism 30.

[0013] Frame 3 is a component that supports the main body 2's components (4-8, 20, 30). Frame 3 is made of, for example, steel, aluminum alloy, chromium-molybdenum steel, carbon (carbon fiber reinforced plastic), or a combination thereof. Frame 3 mainly consists of, for example, a top tube 11, a down tube 12, a seat tube 13, a head tube 14, a seat stay 15, a chain stay 16, and a bottom bracket shell 17.

[0014] The top tube 11 is connected at its front end to the head tube 14 and at its rear end to the upper end of the seat tube 13, and extends generally in the front-to-back direction. The down tube 12 is connected at its front end to the head tube 14 and at its rear end to the bottom bracket shell 17, and extends diagonally downward and backward. The seat tube 13 is connected at its upper end to the rear end of the top tube 11 and at its lower end to the bottom bracket shell 17, and extends diagonally downward and forward. The seat tube 13 supports the saddle 5 at its upper end so that it can be raised and lowered.

[0015] The head tube 14 is connected to the front ends of the top tube 11 and the down tube 12 and extends diagonally forward and downward. The steering column 8 of the front fork 4 is rotatably inserted through the head tube 14. The steering column 8 supports the handlebars 6 at its upper end. The front fork 4 extends diagonally forward and downward from the head tube 14 and rotatably supports the front wheel 7F at its lower end. As a result, the direction of the front wheel 7F (i.e., the direction of travel of the electric assist bicycle 1) changes when the handlebars 6 are operated by the user. In other words, the front wheel 7F is a steering wheel whose steering angle can be changed (in other words, steerable) by the handlebars 6, and is an example of a first wheel.

[0016] The seat stay 15 is connected at its front end to the seat tube 13 and extends diagonally downward and rearward. The chain stay 16 is connected at its front end to the bottom bracket shell 17 and extends generally rearward. The rear wheel 7B is rotatably supported at the connection point (i.e., the rear end) of the seat stay 15 and chain stay 16.

[0017] The pedaling force transmission mechanism 20 is a mechanism that transmits the pedaling force (human power torque TH) of a user sitting on the saddle 5 to the rear wheel 7B. The pedaling force transmission mechanism 20 mainly includes, for example, a crankshaft 21, a pair of crank arms 22L and 22R, a pair of pedals 23L and 23R, a drive gear 24, a driven gear 25, and a chain 26. The pedaling force transmission mechanism 20 (more specifically, a pair of pedals 23L and 23R) is an example of an input part to which the human power torque TH (human power output PH) for driving the rear wheel 7B is input. The rear wheel 7B is a drive wheel that is driven by the pedaling force transmitted by the pedaling force transmission mechanism 20 and is an example of the second wheel.

[0018] The crankshaft 21 extends in the left - right direction and is rotatably supported by the bottom bracket shell 17. The crank arms 22L and 22R have one end connected to both ends of the crankshaft 21 and extend in a direction perpendicular to the crankshaft 21. Also, the pedals 23L and 23R are rotatably attached to the other ends of the crank arms 22L and 22R. The drive gear 24 is attached to the crankshaft 21 and rotates integrally with the crankshaft 21. The driven gear 25 is attached to the rear wheel 7B and rotates integrally with the rear wheel 7B. The chain 26 is looped around the drive gear 24 and the driven gear 25.

[0019] When a user sitting on the saddle 5 steps on the pedals 23L and 23R, the crankshaft 21 rotates together with the drive gear 24 by the pedaling force transmitted by the crank arms 22L and 22R. The rotation of the drive gear 24 is transmitted to the driven gear 25 through the chain 26. The driven gear 25 shifts the rotation of the drive gear 24 transmitted through the chain 26 according to the gear ratio of the drive gear 24 and the driven gear 25 and rotates the rear wheel 7B. Note that the pedaling force transmission mechanism 20 may include a plurality of driven gears that rotate integrally with the rear wheel 7B and a derailleur that switches the driven gear around which the chain 26 is looped among the plurality of driven gears.

[0020] The braking mechanism 30 is a mechanism that brakes the electric assist bicycle 1 in accordance with a user's operation. The braking mechanism 30 mainly includes, for example, a pair of brake levers 31L and 31R, a front brake 32, and a rear brake 33.

[0021] The brake levers 31L and 31R are attached to the handle 6. The brake lever 31L is operated by the user's left hand, and the brake lever 31R is operated by the user's right hand. When the brake lever 31R is operated, the front brake 32 clamps the rim of the front wheel 7F to brake the front wheel 7F. When the brake lever 31L is operated, the rear brake 33 clamps the rim of the rear wheel 7B to brake the rear wheel 7B. Note that the front brake 32 and the rear brake 33 may clamp a disk that rotates integrally with the wheel 7 instead of clamping the rim of the wheel 7.

[0022] [Configuration of Motor System 100] As shown in FIGS. 1 and 2, the motor system 100 mainly includes, for example, a front wheel motor 102F and a rear wheel motor 102B (hereinafter, these may be collectively referred to as "wheel motors 102") and a motor control device 103. The motor system 100 is a system that controls the driving of the front wheel motor 102F and the rear wheel motor 102B using the electric power stored in the battery 101 (power source). Further, a torque sensor 110, a cadence sensor 111, and a vehicle speed sensor 112 are connected to the motor system 100.

[0023] The front wheel motor 102F is an example of the first motor, and the rear wheel motor 102B is an example of the second motor. However, the rear wheel motor 102B may be the first motor, and the front wheel motor 102F may be the second motor.

[0024] Battery 101 stores power to operate the wheel motor 102 and the motor control device 103. Battery 101 may store power supplied from a commercial power source via a cable (not shown), or it may store regenerative power generated by the wheel motor 102. Battery 101 is detachably attached to the upper surface of the down tube 12, for example, as shown in Figure 1. However, battery 101 is not limited to being installed in the position shown in Figure 1, but can be installed at any position on the main body 2.

[0025] The wheel motor 102 is an electric motor driven by power supplied from the battery 101 via the motor control device 103. The wheel motor 102 is driven according to the control of the motor control device 103. The front wheel motor 102F is mounted on the hub of the front wheel 7F, for example, as shown in Figure 1, and rotates the front wheel 7F. Similarly, the rear wheel motor 102B is mounted on the hub of the rear wheel 7B, for example, and rotates the rear wheel 7B.

[0026] More specifically, the wheel motor 102 assists in driving the main body 2 with a predetermined output [W]. The wheel motor 102 is, for example, a brushed motor that rotates by the repeated contact and non-contact of brushes and commutators. The brushed motor generates a predetermined output through ON / OFF control of the motor control device 103. Brushless motors have a simpler structure and are less expensive compared to stepping motors and servo motors. However, the specific example of the wheel motor 102 is not limited to a brushed motor.

[0027] The outputs of the front wheel motor 102F and the rear wheel motor 102B may be the same or different, as long as they are predetermined fixed values. In this embodiment, the predetermined output generated by the front wheel motor 102F is referred to as the "first output P1," and the predetermined output generated by the rear wheel motor 102B is referred to as the "second output P2." The values ​​of the first output P1 and the second output P2 are stored in the motor control device 103.

[0028] The motor control device 103 determines the assist output PA [W] that the entire motor system 100 can output, based on the human power output PH [W] input to the pedal force transmission mechanism 20. The motor control device 103 also individually controls the ON / OFF status of the front wheel motor 102F and the rear wheel motor 102B based on the determined assist output PA. ON control means supplying DC power stored in the battery 101 to the wheel motor 102 to drive the wheel motor 102. OFF control means stopping the supply of power to the wheel motor 102 to stop the wheel motor 102.

[0029] As an example, the motor control device 103 includes a CPU and memory. The motor control device 103 then performs the processes described later by having the CPU execute a program stored in memory. As another example, the motor control device 103 may be implemented using hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0030] The torque sensor 110 detects the human-powered torque TH [Nm] input to the pedaling force transmission mechanism 20 (crank arms 22L, 22R) and outputs a torque signal indicating the detected human-powered torque TH to the motor control device 103. The cadence sensor 111 detects the human-powered rotation speed NH [rpm] of the crank arms 22L, 22R and outputs a cadence signal indicating the detected human-powered rotation speed NH to the motor control device 103. The vehicle speed sensor 112 detects the vehicle speed V [km / h] of the electric assist bicycle 1 and outputs a vehicle speed signal indicating the detected vehicle speed V to the motor control device 103.

[0031] The various sensors (110-112) can be any known form of sensor. Furthermore, the various sensors (110-112) can be attached to any position on the electric assist bicycle 1. The vehicle speed sensor 112 may, for example, detect the vehicle speed V of the electric assist bicycle 1 based on a position signal received from a GPS (Global Positioning Satellite).

[0032] [Motor control processing] Figure 3 is a flowchart of the motor control process. Figure 4 is a diagram showing an example of the relationship between vehicle speed and assist ratio. Figure 5 is a diagram showing an example of the relationship between the assist output PA and the state of each motor 102F and 102B. The motor control process is a process that individually controls the ON / OFF state of the front wheel motor 102F and the rear wheel motor 102B based on the assist output PA. The motor control device 103 repeatedly executes the motor control process shown in Figure 3 at predetermined time intervals, for example, during the period when the motor system 100 is powered ON (more specifically, when the assist switch is ON).

[0033] First, the motor control device 103 acquires the detected values ​​from various sensors (110 to 112) (S11). In this embodiment, the motor control device 103 acquires, for example, the human-powered torque TH detected by the torque sensor 110, the human-powered rotational speed NH detected by the cadence sensor 111, and the vehicle speed V detected by the vehicle speed sensor 112.

[0034] Next, the motor control device 103 determines the assist output PA based on the detection results of various sensors (110-112) (S12). The motor control device 103 determines the human power output PH by substituting, for example, the human power torque TH and the human power rotation speed NH into the following equation 1. The human power output PH is the output input to the pedaling force transmission mechanism 20 by the user of the electric assist bicycle 1. r is the length of the crank arms 22L and 22R (the turning radius of the pedals 23L and 23R). PH=2πr×TH×NH / 60 (Formula 1)

[0035] Furthermore, the motor control device 103 determines the assist ratio corresponding to the vehicle speed V of the electric assist bicycle 1 based on the relationship shown in Figure 4. In addition, the motor control device 103 determines the assist output PA by multiplying the human power output PH by the assist ratio (i.e., based on the magnitude of the human power output PH). The assist output PA is the maximum output that the motor system 100 can generate.

[0036] As shown in Figure 4, the greater the human power output PH, the greater the assist output PA. Also, the faster the vehicle speed V, the smaller the assist output PA becomes. More specifically, when the vehicle speed V is less than 10 km / h, the assist ratio is 2 (i.e., the assist output PA is twice the human power output PH), and between 10 and 24 km / h, the assist ratio gradually decreases as the vehicle speed V increases, and when the vehicle speed V is above the assist limit (24 km / h), the assist ratio (i.e., the assist output PA) becomes 0.

[0037] Next, the motor control device 103 compares the assist output PA determined in step S12 with the preset first output P1 and second output P2 (S13, S14). More specifically, the motor control device 103 compares the assist output PA with the first output P1 (S13), and compares the assist output PA with the sum of the first output P1 and the second output P2 (=P1+P2) (S14).

[0038] Then, if the assist output PA is less than the first output P1 (S13: Yes), the motor control device 103 stops the front wheel motor 102F and the rear wheel motor 102B (S15). At this time, the motor system 100 does not assist in driving the main body 2.

[0039] Furthermore, the motor control device 103 drives the front wheel motor 102F and stops the rear wheel motor 102B (S16) when the assist output PA is equal to or greater than the first output P1 and less than the sum of the first output P1 and the second output P2 (=P1+P2). At this time, the motor system 100 assists the driving of the main body 2 (front wheel 7F) with the first output P1.

[0040] Furthermore, the motor control device 103 drives the front wheel motor 102F and the rear wheel motor 102B when the assist output PA is equal to or greater than the sum of the first output P1 and the second output P2 (S13: No & S14: No) (S17). At this time, the motor system 100 assists in driving the main body 2 (front wheels 7F and rear wheels 7B) with the sum of the first output P1 and the second output P2.

[0041] In other words, for example in the example in Figure 5, the motor system 100 does not assist in driving the main body 2 (does not generate an assist output) between times t0-t1 and after time t4. Furthermore, the motor system 100 assists in driving the main body 2 (front wheels 7F) with the first output P1 between times t1-t2 and between times t3-t4. In addition, the motor system 100 assists in driving the main body 2 (front wheels 7F and rear wheels 7B) with the sum of the first output P1 and the second output P2 between times t2-t3.

[0042] [Effects of the Embodiment] In the motor system 100 according to the above embodiment, the output actually generated is varied in steps within the range of the assist output PA determined in step S12. According to the above embodiment, the aforementioned control can be achieved by ON / OFF control of the wheel motor 102. This simplifies the control of the motor system 100 compared to dynamically controlling the power of each motor.

[0043] Furthermore, according to the above embodiment, by employing a brush motor as the wheel motor 102, the motor system 100 can be realized at a lower cost compared to cases where a stepping motor or servo motor is employed.

[0044] Note that the motor system 100 is not limited to two motors. As another example, the motor system 100 may have only one motor. This motor only needs to assist in driving either the front wheel 7F, the rear wheel 7B, or the crankshaft 21. In this case, the control of the motor control device 103 corresponds to the one shown in Figure 3, with steps S14 and S17 omitted. As yet another example, the motor system 100 may have three or more motors. The case with three motors will be explained below with reference to Figure 6, and the case with four motors will be explained with reference to Figure 7.

[0045] [Example 1] Figure 6 shows another example of the relationship between the assist output PA and the state of each motor. The motor system 100 according to Modification 1 includes a front wheel motor that drives the front wheel 7F with a first output P1, a rear wheel motor that drives the rear wheel 7B with a second output P2, and a crank motor that drives the crankshaft 21 with a third output P3. The front wheel motor, rear wheel motor, and crank motor are, for example, brush motors.

[0046] The front wheel motor is an example of the first motor, the rear wheel motor is an example of the second motor, and the crank motor is an example of the third motor. However, it is sufficient that one of the front wheel motor, rear wheel motor, or crank motor is the first motor, another is the second motor, and yet another is the third motor. Also, the first output P1, the second output P2, and the third output P3 may be the same value or different values, as long as they are predetermined fixed values.

[0047] In the modified example 1, the motor control device 103 stops the front wheel motor, rear wheel motor, and crank motor when the assist output PA is less than the first output P1. At this time, the motor system 100 does not assist in driving the main body 2.

[0048] Furthermore, the motor control device 103 drives the front wheel motor and stops the rear wheel motor and crank motor when the assist output PA is equal to or greater than the first output P1 and less than the sum of the first output P1 and the second output P2 (=P1+P2). At this time, the motor system 100 assists the driving of the main body 2 (front wheel 7F) with the first output P1.

[0049] Furthermore, the motor control device 103 drives the front wheel motor and the rear wheel motor and stops the crank motor when the assist output PA is greater than or equal to the sum of the first output P1 and the second output P2, and less than the sum of the first output P1, the second output P2, and the third output P3 (= P1 + P2 + P3). At this time, the motor system 100 assists the driving of the main body 2 (front wheel 7F and rear wheel 7B) with the sum of the first output P1 and the second output P2.

[0050] Furthermore, the motor control device 130 drives the front wheel motor, rear wheel motor, and crank motor when the assist output PA is equal to or greater than the sum of the first output P1, the second output P2, and the third output P3. At this time, the motor system 100 assists in driving the main body 2 (front wheel 7F, rear wheel 7B, and crank shaft 21) with the sum of the first output P1, the second output P2, and the third output P3.

[0051] In other words, for example in the example in Figure 6, the motor system 100 does not assist in driving the main body 2 (does not generate an assist output) between times t0-t1 and after time t6. The motor system 100 also assists in driving the main body 2 (front wheel 7F) with the first output P1 between times t1-t2 and between times t5-t6. The motor system 100 also assists in driving the main body 2 (front wheel 7F and rear wheel 7B) with the sum of the first output P1 and the second output P2 between times t2-t3 and between times t4-t5. Furthermore, the motor system 100 assists in driving the main body 2 (front wheel 7F, rear wheel 7B, and crankshaft 21) with the sum of the first output P1, the second output P2, and the third output P3 between times t3-t4.

[0052] [Differentiation 2] Figure 7 shows yet another example of the relationship between the assist output PA and the state of each motor. The motor system 100 according to Modification 1 includes a first front wheel motor that drives the front wheel 7F with a first output P1, a first rear wheel motor that drives the rear wheel 7B with a second output P2, a second front wheel motor that drives the front wheel 7F with a third output P3, and a second rear wheel motor that drives the rear wheel 7B with a fourth output P4. The first front wheel motor, the first rear wheel motor, the second front wheel motor, and the second rear wheel motor are, for example, brush motors.

[0053] The first front wheel motor is an example of the first motor, the first rear wheel motor is an example of the second motor, the second front wheel motor is an example of the third motor, and the second rear wheel motor is an example of the fourth motor. However, it is sufficient that one of the first front wheel motor, first rear wheel motor, second front wheel motor, and second rear wheel motor is the first motor, another is the second motor, another is the third motor, and yet another is the fourth motor. Also, the first output P1, second output P2, third output P3, and fourth output P4 may be the same value or different values, as long as they are predetermined fixed values.

[0054] In the modified example 2, the motor control device 103 stops the first front wheel motor, the first rear wheel motor, the second front wheel motor, and the second rear wheel motor when the assist output PA is less than the first output P1. At this time, the motor system 100 does not assist in driving the main body 2.

[0055] Furthermore, the motor control device 103 drives the first front wheel motor and stops the first rear wheel motor, the second front wheel motor, and the second rear wheel motor when the assist output PA is equal to or greater than the first output P1 and less than the sum of the first output P1 and the second output P2 (=P1+P2). At this time, the motor system 100 assists the driving of the main body 2 (front wheel 7F) with the first output P1.

[0056] Furthermore, the motor control device 103 drives the first front wheel motor and the first rear wheel motor, and stops the second front wheel motor and the second rear wheel motor, when the assist output PA is greater than or equal to the sum of the first output P1 and the second output P2, and less than the sum of the first output P1, the second output P2, and the third output P3 (= P1 + P2 + P3). At this time, the motor system 100 assists the driving of the main body 2 (front wheels 7F and rear wheels 7B) with the sum of the first output P1 and the second output P2.

[0057] Furthermore, the motor control device 130 drives the first front wheel motor, the first rear wheel motor, and the second front wheel motor, and stops the second rear wheel motor, when the assist output PA is greater than or equal to the sum of the first output P1, the second output P2, and the third output P3, and less than the sum of the first output P1, the second output P2, the third output P3, and the fourth output P4 (=P1+P2+P3+P4). At this time, the motor system 100 assists the driving of the main body 2 (front wheels 7F and rear wheels 7B) with the sum of the first output P1, the second output P2, and the third output P3.

[0058] Furthermore, the motor control device 130 drives the first front wheel motor, the first rear wheel motor, the second front wheel motor, and the second rear wheel motor when the assist output PA is equal to or greater than the sum of the first output P1, the second output P2, the third output P3, and the fourth output P4. At this time, the motor system 100 assists in driving the main body 2 (front wheels 7F and rear wheels 7B) with the sum of the first output P1, the second output P2, the third output P3, and the fourth output P4.

[0059] In other words, for example in the example in Figure 7, the motor system 100 does not assist in driving the main body 2 (does not generate an assist output) between times t0-t1 and after time t8. The motor system 100 also assists in driving the main body 2 (front wheels 7F) with the first output P1 between times t1-t2 and between times t7-t8. The motor system 100 also assists in driving the main body 2 (front wheels 7F and rear wheels 7B) with the sum of the first output P1 and the second output P2 between times t2-t3 and between times t6-t7. The motor system 100 also assists in driving the main body 2 (front wheels 7F and rear wheels 7B) with the sum of the first output P1, the second output P2, and the third output P3 between times t3-t4 and between times t5-t6. Furthermore, the motor system 100 assists in driving the main body 2 (front wheels 7F and rear wheels 7B) between times t4 and t5 with the sum of the first output P1, second output P2, third output P3, and fourth output P4.

[0060] As shown in Modification 1, the drive of the main body 2 can be stably assisted by distributing the motor-assisted parts. Also, as shown in Modification 2, the drive of the main body 2 can be stably assisted by alternately increasing (decreasing) the assist of the front wheel 7F and the rear wheel 7B in accordance with the increase (decrease) of the assist output PA. Furthermore, as shown in Modifications 1 and 2, the fluctuation in the output generated by the motor system 100 becomes more gradual by increasing the number of motors. Note that the above embodiments and Modifications 1 and 2 can be combined in any combination.

[0061] [Other variations] The electric vehicles to which the motor system 100 can be applied are not limited to the electric assist bicycle 1. As another example, the electric vehicles to which the motor system 100 can be applied may have multiple front wheels 7F and / or rear wheels 7B, or may have a pair of wheels on the left and right sides instead of front wheels 7F and rear wheels 7B. As yet another example, the electric vehicles to which the motor system 100 can be applied are not limited to those that rotate the wheels 7 by assisting the user's pedaling force with the wheel motor 102, but may also be those that run solely on the propulsion force of the wheel motor 102 (e.g., kick scooters, certain small mopeds). Furthermore, the motor system 100 can be applied not only to electric vehicles but also to any device driven by an electric motor (e.g., radiator fans, power windows, electric oil pumps, etc.).

[0062] Embodiments of the present invention have been described above. It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the described configurations. Furthermore, it is possible to replace some of the configurations of this embodiment with those of other embodiments, and it is also possible to add configurations from other embodiments to the configuration of this embodiment. Moreover, it is possible to add, delete, or replace some of the configurations of this embodiment with those of other embodiments. [Explanation of Symbols]

[0063] 1…Electric assist bicycle, 2…Main body, 3…Frame, 4…Front fork, 5…Saddle, 6…Handlebars, 7B…Rear wheel, 7F…Front wheel, 8…Steering column, 11…Top tube, 12…Down tube, 13…Seat tube, 14…Head tube, 15…Seat stay, 16…Chain stay, 17…Bottom bracket shell, 20…Pedaling force transmission mechanism, 21…Crank axle, 22L,22R…Crank arm, 23L,23R…Pedal, 24…Drive gear, 25…Driven gear, 26…Chain, 30…Brake mechanism, 31L,31R…Brake lever, 32…Front brake, 33…Rear brake, 100…Motor system, 101…Battery, 102B…Rear wheel motor, 102F…Front wheel motor, 103…Motor control device, 110…Torque sensor, 111…Cadence sensor, 112…Vehicle speed sensor

Claims

1. In a motor system that assists the driving of a human-powered vehicle comprising a first wheel, a second wheel, and an input unit to which human power output for driving the second wheel is input, A motor that drives the human-powered vehicle with a predetermined output, The motor control device comprises a motor control device that controls the drive of the motor, The motor control device is Based on the aforementioned human power output, the assist output of the motor system is determined. If the assist output is less than the predetermined output, the motor is stopped. A motor system characterized in that the motor is driven when the assist output is equal to or greater than the predetermined output.

2. In the motor system according to claim 1, The aforementioned motor is A first motor drives one of the first wheel and the second wheel with a first output, The system includes a second motor that drives the other of the first wheel and the second wheel with a second output, The motor control device is If the assist output is less than the first output, the first motor and the second motor are stopped. If the assist output is equal to or greater than the first output and less than the sum of the first and second outputs, the first motor is driven and the second motor is stopped. A motor system characterized in that the first motor and the second motor are driven when the assist output is equal to or greater than the sum of the first output and the second output.

3. In the motor system according to claim 1, The aforementioned motor is A first motor that drives the first wheel, the second wheel, and one of the input units with a first output, A second motor that drives the first wheel, the second wheel, and one of the other input units with a second output, The system includes the first wheel, the second wheel, and a third motor that drives yet another input unit with a third output, The motor control device is If the assist output is less than the first output, the first motor, the second motor, and the third motor are stopped. If the assist output is equal to or greater than the first output and less than the sum of the first and second outputs, the first motor is driven and the second and third motors are stopped. If the assist output is greater than or equal to the sum of the first and second outputs, and less than the sum of the first, second, and third outputs, the first and second motors are driven, and the third motor is stopped. A motor system characterized in that the first motor, the second motor, and the third motor are driven when the assist output is equal to or greater than the sum of the first output, the second output, and the third output.

4. In the motor system according to claim 1, The aforementioned motor is A first motor drives one of the first wheel and the second wheel with a first output, A second motor drives the other of the first wheel and the second wheel with a second output, A third motor that drives one of the first wheel and the second wheel with a third output, The system includes a fourth motor that drives the other of the first and second wheels with a fourth output, The motor control device is If the assist output is less than the first output, the first motor, the second motor, the third motor, and the fourth motor are stopped. If the assist output is equal to or greater than the first output and less than the sum of the first and second outputs, the first motor is driven and the second motor, the third motor, and the fourth motor are stopped. If the assist output is greater than or equal to the sum of the first and second outputs, and less than the sum of the first, second, and third outputs, the first and second motors are driven, and the third and fourth motors are stopped. If the assist output is greater than or equal to the sum of the first, second, and third outputs, and less than the sum of the first, second, third, and fourth outputs, then the first, second, and third motors are driven, and the fourth motor is stopped. A motor system characterized in that the first motor, second motor, third motor, and fourth motor are driven when the assist output is equal to or greater than the sum of the first output, second output, third output, and fourth output.

5. In the motor system according to claim 1, The motor system is characterized in that the motor is a brush motor.

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