JP2006078304A - Torque sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque sensor capable of speedily adapting to the state of anomaly by recognizing anomalies of the torque sensor only by a torque detection signal line without having to provide an anomaly signal line of another system. <P>SOLUTION: In the torque sensor 41 having both an input line 56 to which torque is input and an output line 57 for outputting a detection voltage signal according to the input torque, a previously set anomaly signal is output from the output line 57 continuously to the detection voltage signal when anomalous torque is input from the input line 56. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a torque sensor, and more particularly to a torque sensor used in a system (for example, a battery-assisted bicycle) that is driven according to a torque value detected by detecting torque. More specifically, the present invention relates to such a torque sensor abnormality determination method.

  A battery-assisted bicycle is disclosed in Patent Document 1. In this battery-assisted bicycle, a pedaling force depressed by a pedal is detected by a torque sensor, and auxiliary power corresponding to the pedaling force is applied from a motor. The torque sensor has an input line for inputting torque and an output line for outputting a detection voltage signal in accordance with the input torque. The output line is connected to the control circuit and drives the power assist motor in accordance with the detected torque signal.

  This torque sensor may output an abnormal voltage due to disconnection or deterioration over time. In case of disconnection, the output voltage becomes zero. In the case of deterioration over time, the output voltage decreases and does not correspond to the pedaling force, for example, it always becomes a low voltage close to zero.

  As a torque sensor capable of recognizing such an abnormal state, a torque sensor that incorporates an abnormality determination circuit in the torque sensor itself, detects an abnormality of the sensor by self-diagnosis, and generates an abnormality signal has been put into practical use.

When a torque sensor having a function for discriminating such an abnormal state is used, when the torque sensor recognizes an abnormality and generates an abnormality signal, a control circuit connected to the torque sensor or other device linked to the torque sensor A user recognizes an abnormality by automatic processing or from an alarm device or the like and turns off the power. In this case, the control circuit and other devices are turned on next time without recognizing the abnormality of the torque sensor, and the operation is resumed. For this reason, the treatment for the abnormality of the torque sensor is delayed.

Further, since the abnormal signal is output from a line different from the torque detection output line, the line wiring becomes complicated.
Further, as described above, when the detected voltage of the torque sensor becomes zero or near zero, the control circuit cannot determine whether the pedal force is actually input or whether the torque sensor is abnormal. Accordingly, since the control circuit continues the control as it is with the detected value zero as a normal value without the pedaling force, the control circuit continues to operate without the auxiliary power from the motor being applied (the auxiliary power is not applied when the pedaling force is zero). For this reason, the user cannot immediately recognize the abnormality, and cannot deal with or delay the torque sensor abnormality.

  In addition, when the state where the output voltage is zero is an abnormality of the torque sensor, it is conceivable to provide an abnormal signal line of another system in order to recognize this and recognize the abnormal state and to cope with the abnormality immediately. However, if a separate signal line is provided, the structure becomes complicated and the cost increases.

Japanese Patent Laid-Open No. 11-171081

  The present invention is based on the above-described prior art, and can provide a torque sensor that can quickly recognize an abnormality of the torque sensor and deal with an abnormal state quickly by using only a torque detection signal line without providing an abnormal signal line of another system. The purpose is to provide.

  In order to achieve the above object, the invention of claim 1 is directed to a torque sensor having an input line to which torque is input and an output line for outputting a detection voltage signal according to the input torque. A torque sensor is provided that outputs a preset abnormality signal following the detection voltage signal from the output line when torque is input.

  According to a second aspect of the present invention, in the first aspect of the invention, the abnormal torque is zero.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the abnormal signal is an unused constant voltage signal.

  The invention of claim 4 provides a battery-assisted bicycle provided with the torque sensor according to claim 1, 2 or 3.

  According to the first aspect of the invention, when an abnormal torque continues, an abnormal signal is sent from the torque detection output signal line following the torque output signal. Therefore, without making the structure complicated, it is possible to promptly send an abnormal signal to make other devices and users recognize the abnormality of the torque sensor.

  According to the invention of claim 2, when the output voltage becomes zero due to disconnection, an abnormal signal is output subsequent to this output voltage. Therefore, on the side receiving the output to which the output line of the torque sensor is connected, An abnormality in the torque sensor can be immediately recognized from the signal on the torque sensor output line.

  According to the invention of claim 3, in a torque sensor that normally outputs a torque detection signal of about 0 to 2V, after the detection signal of 0V is output, an unused constant voltage of about 5V, for example, is transmitted as an abnormal signal. Therefore, it is possible to form an abnormal signal with a simple circuit and reliably recognize the sensor abnormality.

  According to the invention of claim 4, when an abnormality occurs in the torque sensor, it is possible to realize an electrically assisted bicycle that can immediately recognize the abnormality and deal with the abnormality and always obtain effective auxiliary power.

FIG. 1 is a side view of a battery-assisted bicycle to which the present invention is applied.
The battery-assisted bicycle 1 has a head pipe 4 through which the center steering shaft 3 of the left and right handles 2 is inserted, and the steering shaft 3 is connected to the left and right front forks 5 to operate the direction of the front wheels 6. A down tube 7 is joined to the head pipe 4 and connected to a seat tube 9 below the saddle 8. A power unit 11 that integrates an electric drive system such as a traveling electric motor 37 covered with a cover 10 at the lower ends of the down tube 7 and the seat tube 9 and a human power drive system such as a pedal crankshaft 12 is supported. Is done. In the power unit 11, the pedal force from the pedal 15 and the motor force are fused by a resultant force mechanism (not shown) arranged coaxially with the pedal crankshaft 12. The resultant force mechanism is composed of, for example, a planetary gear mechanism, and is provided with a torque sensor (not shown) that is connected to the planetary gear mechanism and is displaced in accordance with the pedaling force from the pedal 15.

An auxiliary power control controller 13 is provided at the rear of the power unit 11. The controller 13 is constituted by a microcomputer for driving and controlling the motor 37 so as to obtain an assist ratio corresponding to the speed based on the vehicle speed obtained by a vehicle speed calculating means (FIG. 2) described later. The installation position of the controller 13 is not limited to the example shown in the figure, and may be in the middle of the down tube 7 or in the cover 10, in the middle of the front fork 5, the chain stay 38, the seat stay 39, or any other suitable position. Good.

  A battery case 14 is detachably provided on the rear side of the seat tube 9 below the saddle 8, and a battery for driving the motor 37 is accommodated therein. The pedaling force and auxiliary power fused by the resultant force mechanism on the pedal crankshaft 12 are transmitted to the rear wheel 17 by the chain 16 to rotate. The hub 18 of the rear wheel 17 is provided with a sprocket (not shown) for transmitting the rotation of the chain 16 and a rotary or slide type transmission gear mechanism (not shown). An actuator composed of a motor or a solenoid for driving the mechanism is mounted.

FIG. 2 is a block configuration diagram of a torque control device for a battery-assisted bicycle according to an embodiment of the present invention, and FIG. 3 is a block diagram of a basic configuration of the present invention in a main part thereof.
The torque control device includes a torque sensor 41 for detecting pedal depression force, a controller 43 for calculating a drive current of an electric motor 42 composed of a pulse motor based on the detected torque of the torque sensor 41, and driving and controlling the drive current. A motor drive circuit 44 for driving the electric motor 42 by a drive signal from the controller 43, a current detection circuit (ammeter) 45 for detecting the current of the motor 42, and a rotation for detecting the rotation of the motor 42 And an encoder 46.

  The controller 43 is composed of, for example, a CPU, and includes a motor speed calculation means 47, a vehicle speed calculation means 48, a torque sensor value processing filter means 49, a torque-current calculation means 50, a duty calculation means 51 based on a preset software program or hardware circuit. With.

  The torque sensor 41 incorporates an abnormality determination circuit 55 for self-diagnosis. Torque due to the pedal force is input to the torque sensor 41 via the input line 56, and a voltage value corresponding to the input torque is output as a detected torque signal value via the output line 57.

  In this embodiment, when an abnormal torque is continuously input from the input line 56 for a certain time due to disconnection or aging deterioration, the abnormality determination circuit detects this abnormal state and, as will be described later, the abnormality is detected via the output line 57. Output a signal. That is, an abnormal signal is output following the detected torque signal via the output line 57 that outputs the detected torque signal.

  When the power switch 54 (FIG. 3) is turned on, the pedal depression force detection operation by the torque sensor 41 is started. The pedal depression force detected by the torque sensor 41 is noise-removed by the torque sensor value processing filter means 49 and is processed based on the detected torque and the vehicle speed, and an output voltage (processing torque value) corresponding to the pedal depression force. Is obtained. The vehicle speed is calculated by the motor speed calculation means 47 and the vehicle speed calculation means 48 in the controller 43 based on the pulse signal from the encoder 46 and is input to the torque sensor value processing filter means 49.

  The machining torque value after machining is input to the torque-current calculation means 50, and a current command value corresponding to the machining torque is calculated. Based on this current command value, the duty ratio of the drive pulse is calculated by the duty calculation means 51 and is input to the motor drive circuit 44 as a PWM output to drive the motor 42. The drive current of the motor 42 is detected by the current detection circuit 45 and returned to the duty calculation circuit 51 for feedback control.

  When a zero-torque signal is input from the input line 56 to the torque sensor 41 due to an abnormality such as disconnection, the abnormality determination circuit 55 in the torque sensor 41 detects this abnormal state and sends an abnormal signal from the output line 57. To do. This abnormality signal is sent to the alarm circuit 52, and the LED 53 is turned on to display an abnormality. The abnormal signal from the output line 57 is also sent to the torque-current calculation circuit 50. When an abnormal signal is input, the torque-current calculation circuit 50 stops the calculation process of the current command value. Therefore, the assist motor 42 stops and no auxiliary power is applied. When the output line 57 of the torque sensor 41 is connected to an abnormality detection circuit (not shown) or the like and an abnormality signal is input to the abnormality detection circuit, an assist stop command is sent to the torque-current calculation circuit 50 to assist the assist motor 42. May be stopped.

  When a torque zero signal is input from the input line 56, the abnormality determination circuit 55 of the torque sensor 41 determines whether the zero torque state is due to disconnection or whether the pedal effort is actually zero. As this determination method, for example, if the torque is zero when the pedal crankshaft rotates and the one-way clutch operates without idling and torque is transmitted, it can be determined that the disconnection is abnormal. When such an abnormal state is detected, the torque sensor 41 outputs an abnormal signal following the detection signal of zero torque. In this case, in order to avoid erroneous detection due to noise or the like, an abnormal signal may be output after a certain time has elapsed.

FIG. 4 is an explanatory diagram of an abnormal signal.
(A) shows the input waveform of normal pedal effort. Draw a smooth sinusoidal curve according to the rotation angle of the pedal crankshaft. (B) shows the trapezoidal continuous waveform output continuously from the zero output state. (C) shows the output of a constant voltage V2 that rises sharply from the zero output state. The constant voltage V2 is an unused voltage value that is not normally output and is larger than the peak voltage V1 of (A).

  The present invention can be used for a torque sensor of a battery-assisted bicycle. In addition, it can be used as a torque sensor that can be used in any device that operates a system based on torque.

The side view of the battery-assisted bicycle to which the present invention is applied. The block diagram of the torque control apparatus of the battery-assisted bicycle which concerns on this invention. The principal part structure and operation | movement figure of the torque control apparatus of FIG. The output waveform figure of the abnormal signal of a torque sensor.

Explanation of symbols

1: Electric assist bicycle, 2: Handle, 3: Steering shaft, 4: Head pipe, 5: Front fork, 6: Front wheel, 7: Down tube, 8: Saddle, 9: Seat tube, 10: Cover, 11: Power unit ,
12: Pedal crankshaft, 13: Controller, 14: Battery case,
15: pedal, 16: chain, 17: rear wheel, 18: hub, 37: electric motor, 38: chain stay, 39: seat stay, 41: torque sensor, 42: electric motor, 43: controller, 44: motor drive Circuit 45: current detection circuit (ammeter) 46: encoder 47: motor speed calculation means 48: vehicle speed calculation means 49: torque sensor value processing means 50: torque-current calculation means 51: duty calculation Means 52: Alarm circuit 53: LED 54: Power switch 55: Abnormality determination circuit 56: Input line 57: Output line

Claims (4)

In a torque sensor having an input line to which torque is input and an output line for outputting a detection voltage signal according to the input torque,
A torque sensor, wherein when an abnormal torque is input from the input line, a preset abnormal signal is output from the output line following the detected voltage signal.   The torque sensor according to claim 1, wherein the abnormal torque is zero.   The torque sensor according to claim 1, wherein the abnormal signal is an unused constant voltage signal. A battery-assisted bicycle comprising the torque sensor according to claim 1, 2 or 3.

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