Confidential Presentation of Torque Sensor（TQ2） This is a presentation of a newly developed Torque Sensor for an electric power-assisted bicycle. March,2012 Mr. M..Baba / BM-Technology Configuration of Electric Power-assisted Bicycle Electric Power-assisted Bicycle Battery-assisted bicycles are a bicycle and the interim vehicles of a motorcycle, detect power, number of rotations, etc. which step on a pedal by a sensor, and assist the power to step on by the carried motor. Although the right figure is one example of a commercial electric assistant bicycle, it mainly consists of the following units. Hand Controller Battery Main Control Unit 1.Body 2.Main Control Unit 3.Battery 4.Torque Sensor 5.Motor 6.Hand controller • Body Torque Sensor It is a sensor unit which detects the power which steps on a pedal, and outputs the important signal used as the basis of motor drive control. Since there is no general-purpose sensor marketed, each assistant bicycle maker developed uniquely and has included in the in-house product. 2015/10/1 Torque Sensor BMT Motor 2 Torque Sensor Development Schedule 2011.12.21 @BMT The main features • • Radio, a thin shape Distortion detection system L e v e l ４G Step3 TQ4 ３G Step2 • • TQ3 Starting torque detection Movement detection system • Cheapness, a thin shape Phase difference detection system @2,000 ２G TQ2 Step1 • @3,000 Target price @1,500 OEM BASIC TQ1 TQ1xx @1,000 Time 2015/10/1 BMT 3 Technical-specifications outline Model : TQ-2/TQ-2R Item 2015/10/1 TQ-2／TQ-2R* Load detecting scheme Movement detection Detection principle The relative distance between a load side and the non-load side is proportional to load. Load signal output Analog voltage Start-up load detection yes Number-of-rotations detection yes* Direction of Rotation Judges from a voltage output. * Output cable 4 core shield cable Built-in electric circuit Amplification shaping circuit Power supply for operation External supply Body attachment and wiring Required Cost Low BMT 4 Appearance of torque sensor TQ-2 Surface Number of teeth: 38 Crank length: 170 mm Back 2015/10/1 BMT 5 The comparison table of an another type torque sensor and TQ2 Detection principle Maker Feature Magnetost riction Panasoni c A twist of the metal bar by load is detected by non-contact by a magnetostrictive element. -The accuracy of a detection gap is required. vertical migration Sanyo Movement of the direction of rotation by load is changed perpendicularly, and change of the amount of inductance is detected by noncontact. - Thickness is needed for vertical migration. Body Cost Difficulty Processing accuracy High High High Low Low Mid. Exclusi ve use Rotation gap Yamaha Two gear rotation differences by load are detected by non-contact. - Structures are complexity, a motor, and solid construction. High High High Rotational transfer BMT （TQ2) （TQ2R) The movement of the direction of rotation is detected by non-contact. - Structure is easy and can make low-cost. . - Wearing into the body is simply possible. - By kit-izing with required parts, production of an assistant bicycle is simply possible. Low Mid. Low 2015/10/1 BMT Wide use 6 The feature of torque sensor TQ-2 • Feature 1. For [ general-purpose ] the bodies •Product specification (reference) The body for exclusive use is unnecessary and it can apply it to the usual bicycle frame easily. 2. 3. 4. Item Thin form Since product thickness is thin, various bicycle frames are suited. Moreover, it can respond also to dedicating in a chain cover. Attachment is easy. Attachment can be simply done for the body. The body can also use the usual thing as it is. Number-of-rotations output (only TQ2R *) The number of rotations of a crank can be outputted (6 p/r). An output becomes a pulse shape. 5. Treading strength proportionality output DC voltage by the linear output proportional to the power which steps on a pedal is outputted. 6. Easy structure Spec. 1 Load range 0 ‐ 65kgf (170mm) 2 Maximum pedal load 150kgf (170mm) 3 Load output voltage 0.8 –3.2 V(Max.) 4 Output cable 30Cm(4 core shield) 5 Output signal +3.3/Torq./Rot./Gnd 6 Output data Load － DC-Voltage Rtation － Pulse(6p/r)* 7 Body attachment Blade spring-like board 8 Voltage/current DC3.3V／10mA 9 Outside dimension 160Φｘ21H Weight 800g (a crank is not included) 10 Component parts were reduced according to an easy structure, and low cost was realized. 2015/10/1 BMT 7 The output characteristic of a built-in load sensor Load characterization TQ-2 Output characteristic (load) 3.0 Load 0 5.5 10.5 15.5 20.6 25.6 30.6 35.6 40.6 45.7 50.7 Vout 0.35 0.38 0.69 1.09 1.43 1.77 2.08 2.37 2.62 2.78 2.80 2.5 2.0 Ave. 1.5 1.0 0.5 Load(kg) 0.0 0 2015/10/1 10 BMT 20 30 40 50 60 8
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