JP2011217542A - Actuator system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator system wherein the size and cost of the equipment can be reduced and torque value detection accuracy is enhanced.SOLUTION: The actuator system includes a controller 54 periodically applies an applied pulse to a magnetostrictive torque sensor 80, calculates a torque value from a detection value detected by the magnetostrictive torque sensor 80 at a sampling timing when a certain time has passed after the application, and PWM-controls a driver 52 that drives a brushless motor 50. The controller 54 further sets the certain time to be shorter than 1/2 of the period of the PWM pulse applied to the driver 52, sets the applied pulse so that three periods of the PWM pulse contain two sampling timing, and determines a sampling timing used for torque value calculation among the two sampling timing based on the duty ratio of the PWM pulse.

Description

  The present invention relates to an actuator system that calculates a torque value from a detection value detected by a magnetostrictive torque sensor.

  Conventionally, it is known that a magnetostrictive torque sensor is affected by a disturbance magnetic field due to rotation of a motor or a magnetic brake, and noise is added to a detected torque signal.

  In Patent Document 1 shown below, a dummy coil is provided separately from a magnetostrictive torque sensor coil, noise received by the dummy coil is determined, and a noise component is detected from a torque signal detected by the magnetostrictive torque sensor. It is described that a more accurate torque signal can be obtained by removing.

JP-A-6-323930

  However, the technique described in Patent Document 1 requires a space for providing a dummy coil and additional parts, which increases the size and cost of the apparatus.

  Therefore, the present invention has been made in view of the conventional problems, and an object of the present invention is to provide an actuator system that can reduce the size and cost of the apparatus and improve the detection accuracy of the torque value.

  In order to achieve the above object, the invention according to claim 1 includes a magnetostrictive torque sensor (80), a brushless motor (50), a drive driver (52) for driving the brushless motor (50), and the magnetostriction. An applied pulse is periodically applied to the torque sensor (80), and a torque value is calculated from a detection value detected by the magnetostrictive torque sensor (80) at a sampling timing after a predetermined time has elapsed from the application, and the calculation is performed. A control means (54) for controlling the drive of the brushless motor (50) by PWM controlling the drive driver (52) according to the torque value, wherein the control means (54) When the predetermined time is set shorter than 1/2 of the period of the PWM pulse applied to the drive driver (52) by the PWM control In addition, the application pulse is set so as to have at least two sampling timings in a constant cycle period of the PWM pulse, and the first PWM pulse applied in the period of the fixed number of cycles is set. After application of the PWM pulse, a first sampling timing for sampling the detected value detected by the magnetostrictive torque sensor (80) at the first sampling timing and a period ½ of the predetermined number of cycles elapses. And a second sampling timing for sampling the detected value detected by the magnetostrictive torque sensor (80) at the first sampling timing, and the control means (54) has a duty ratio of the PWM pulse. When the ratio is greater than or equal to the predetermined duty ratio, the detection is performed at the first sampling timing. The torque value is calculated using the detected value, and when the duty ratio of the PWM pulse is less than the predetermined duty ratio, the torque is calculated using the detection value detected at the second sampling timing. A value is calculated.

  The invention according to claim 2 is the actuator system according to claim 1, wherein the predetermined number of cycles is an odd number of 3 or more, and the control means (54) sets the fixed number of cycles as one set. The application pulse is applied to the magnetostrictive torque sensor at least twice during the one set period.

  The invention according to claim 3 is the actuator system according to claim 1 or 2, wherein the magnetostrictive torque sensor (80) and the brushless motor (50) are integrally configured as an actuator unit (26). In addition, the magnetostrictive torque sensor (80) and the brushless motor (50) are arranged close to each other, and the actuator unit (26) is configured as an assist unit (26) of the assist bicycle (10). Features.

  The invention according to claim 4 is the actuator system according to claim 3, wherein the actuator system includes a crankshaft (38) provided with torque by a driver provided in the assist bicycle (10), and the A drive system mechanism for transmitting the torque applied to the crankshaft (38) to the rear wheels to drive the rear wheels, and the assist unit (26) provides the driving force of the brushless motor (50) to the An assist drive unit (26) for transmitting to a drive system mechanism, the crankshaft (38), the magnetostrictive torque sensor (80), the brushless motor (50), the drive driver (52), and the The magnetostrictive torque sensor (80) is disposed on the crankshaft (38) and integrally holds the control means (54). The bar (52) and the control means (54) are disposed in the same space below the magnetostrictive torque sensor (80), and the brushless motor (50) is located below the crankshaft (38). The magnetostrictive torque sensor (80) is housed in a partitioned space.

  The invention according to claim 5 is the actuator system according to claim 4, wherein the drive driver (52) and the control means (54) are provided for the assist drive unit (26) in the same space. The case (48) is fixed to the wall, and fixed to the left and right wall surfaces facing the center line (112) in the front-rear direction of the assist bicycle (10), and the control means (54) includes the magnetostrictive torque. It is arranged on the unit wall surface on the sensor (80) side.

  According to the first aspect of the present invention, when the duty ratio of the PWM pulse is less than the predetermined duty ratio in the vicinity of 50%, there is a possibility that off noise of the PWM pulse may enter at the first sampling timing. By calculating the torque value with the detection value detected at the timing, the detection accuracy of the torque value can be improved. Further, when the duty ratio of the PWM pulse is equal to or higher than a predetermined duty ratio in the vicinity of 50%, noise does not enter at the first sampling timing, so the torque value is calculated with the detected value detected at the first sampling timing. Thus, the accuracy of detecting the torque value can be improved. In other words, by properly using the sampling timing based on the duty ratio, there is no control delay, and the torque value detection accuracy can be improved. In addition, since the torque value is calculated by determining the sampling timing that is not affected by noise, the actuator system can be reduced in size and cost. Furthermore, it is possible to provide an actuator system for a magnetostrictive torque sensor that does not require a strong magnetic shield.

  According to the second aspect of the present invention, at least one of the odd-numbered periods (one set) of the PWM pulse is affected by noise caused by the PWM pulse without changing the period of the applied pulse of the magnetostrictive torque sensor. No detection value can be obtained.

  According to the third aspect of the present invention, the motor operates as the driving force of the assist bicycle, and is an assist unit in which the influence of the magnetic field due to turning on / off of the PWM pulse is increased as much torque is required. In addition, it is possible to provide an actuator system that can improve the detection accuracy of the torque value.

  According to the fourth aspect of the present invention, the drive driver is disposed in the same space as the magnetostrictive torque sensor, so that the noise influence by the drive driver can be reduced while effectively using the space.

  According to the fifth aspect of the present invention, even if the magnetostrictive torque sensor and the drive driver and the control means are in the same space, the drive driver and the control means are attached to the case wall away from the magnetostrictive torque sensor. Therefore, the drive driver and the control means can be provided at a position where the influence of noise is relatively small.

It is a left view of the assist bicycle provided with the actuator system. It is a left view which shows the principal part of the assist bicycle of FIG. It is the III-III sectional view taken on the line of FIG. It is a detection circuit diagram of a magnetostrictive torque sensor. The voltage waveform when the applied pulse is supplied from the controller to the magnetostrictive torque sensor is shown. It is a figure which shows the rotation direction of the permanent magnet arrange | positioned at the rotor. It is a figure which shows the electric current supplied to the stator coil of a U-phase, V phase, and W phase of a brushless motor by a drive driver, and the state of the permanent magnet at that time. It is a figure which shows the relationship between a magnet and the detection coil of a magnetostrictive torque sensor. Time charts showing the voltages of the U-phase, V-phase, and W-phase stator coils when an alternating current is applied to the stator coils of each phase by the drive driver, and the polarity switching timing detected by the controller by the Hall IC FIG. It is a flowchart which shows the operation | movement of the controller which determines the application timing of an application pulse, a sampling timing, and the OFF timing of an application pulse. It is a time chart which shows the relationship between the PWM pulse applied when a duty ratio is less than 50, and an applied pulse. It is a time chart which shows the relationship between the PWM pulse applied when a duty ratio is 50 or more, and an applied pulse. It is a flowchart which shows acquisition operation | movement of the detected value detected by the magnetostrictive torque sensor. It is a flowchart which shows the calculation operation | movement of the switching time of the energization pattern energized to the U-phase, V-phase, and W-phase stator coil of a brushless motor. It is a flowchart which shows the switching operation of an electricity supply pattern. It is a flowchart which shows the memory | storage operation | movement of the switching timing of the pole of the magnet of a magnetic pole sensor, and the permanent magnet of a rotor. It is a figure which shows the relationship between the permanent magnet of a rotor, and the magnet of a magnetic pole sensor. It is a flowchart which shows the operation | movement which determines the duty ratio of the PWM pulse applied to a drive driver. 12 is a sub-flowchart showing an operation of a detection value selection process in step S9 of FIG.

  DESCRIPTION OF EMBODIMENTS An actuator system according to the present invention will be described in detail below with reference to preferred embodiments and with reference to the accompanying drawings.

  1 is a left side view of an assist bicycle 10 provided with an actuator system, FIG. 2 is a left side view showing a main part of the assist bicycle 10 in FIG. 1, and FIG. 3 is a sectional view taken along line III-III in FIG. is there. The assist bicycle 10 includes a head pipe 12 positioned in front of the vehicle body, a down frame 14 that extends rearward and downward from the head pipe 12, and a seat pipe 16 that rises upward from the rear end of the down frame 14. A front fork 18 extending downward is steerably connected to the head pipe 12, and a front wheel WF is pivotally supported at the lower end of the front fork 18. A handle 20 is provided above the head pipe 12.

  A rear fork 22 extending rearward is disposed at the rear end of the down frame 14, and a rear wheel WR is pivotally supported at the rear end of the rear fork 22. A pair of left and right stays 24 is disposed between the upper portion of the seat pipe 16 and the rear portion of the rear fork 22.

  The down frame 14 and the rear fork 22 support an assist drive unit (assist unit, actuator unit) 26. A seat post 30 having a seat 28 at the upper end is attached to the seat pipe 16 so that the vertical position of the seat 28 can be adjusted. A battery 32 for supplying power to the assist drive unit 26 is detachably attached to the stay 34 of the seat pipe 16 behind the seat pipe 16.

  A crankshaft 38 that extends through the assist drive unit 26 and the sprocket 36 and extends in the width direction of the vehicle body is provided. A crank 42L having a pedal 40L and a crank 42R having a pedal 40R are connected to both sides of the crankshaft 38. . A pedaling torque is applied to the crankshaft 38 by the driver stroking the pedals 40L and 40R. The sprocket 36 rotates due to the pedaling force torque applied to the crankshaft 38, and the rotation of the sprocket 36 is transmitted to the sprocket 46 on the rear wheel WR side via the chain 44, and the rear wheel WR rotates. The sprocket 36, the chain 44, and the sprocket 46 function as a drive system mechanism.

  The assist drive unit 26 is detected by a brushless motor 50, a drive driver 52 that drives the brushless motor 50, PWM control of the drive driver 52, and a magnetostrictive torque sensor, which will be described later, in the casing (case) 48. A controller (control means) 54 that calculates a torque value based on the detected value, a drive gear 58 that rotates in mesh with the drive shaft 56 of the brushless motor 50, and a driven shaft 94 that rotates according to the rotation of the drive gear 58. And the assist sprocket 60 having the. A chain 44 is attached to the assist sprocket 60. The assist drive unit 26 transmits the drive force of the brushless motor 50 to the drive system mechanism. The assist drive unit 26, the crankshaft 38, and the drive system mechanism constitute the actuator system of the present embodiment.

  The controller 54 PWM-controls the drive driver 52 so that the brushless motor 50 generates an assist torque determined by a pedaling force torque applied to the crankshaft 38 and an assist ratio according to the vehicle speed of the assist bicycle 10. The drive driver 52 has a plurality of switching elements of a plurality of phases (in this embodiment, three phases of the UVW phase), and the controller 54 controls on / off of each of the switching elements of the UVW phase with a determined duty ratio. Thus, the drive driver 52 is PWM-controlled. By this PWM control, the drive driver 52 converts the DC power of the battery 32 into three-phase AC power, and converts the three-phase AC current into the U-phase stator coil, V-phase stator coil, and W-phase stator coil of the brushless motor 50. Energize the stator coil. Thereby, the drive shaft 56 of the brushless motor 50 rotates. The controller 54 has a clock circuit and also functions as a timer.

  The auxiliary torque generated by the brushless motor 50 is transmitted to the chain 44 via the drive shaft 56, the drive gear 58, and the assist sprocket 60. Accordingly, the pedaling torque applied to the crankshaft 38 and the auxiliary torque generated by the brushless motor 50 are transmitted to the sprocket 46 on the rear wheel side via the chain 44 when the driver pedals the pedals 40L and 40R. Thus, the rear wheel WR rotates. An idler 62 is provided behind the assist sprocket 60 for increasing the winding angle of the chain.

  The brushless motor 50 includes a rotor 66 having a total of eight N-pole and S-pole permanent magnets 64 arranged alternately in the circumferential direction, and a radial arrangement so as to cover the outer periphery of the rotor 66. A stator 70 having a UVW-phase three-phase stator winding 68 that generates a rotating magnetic field that rotates 66. A drive shaft 56 is provided on the rotation shaft of the rotor 66. Since there are a total of twelve stators 70, there are three U-phase stator windings 68, three V-phase stator windings 68, and three W-phase stator windings 68. The U-phase stator coil of the brushless motor 50 is constituted by three U-phase stator windings 68, the V-phase stator coil is constituted by three V-phase stator windings 68, and the W-phase stator coil is It is constituted by three W-phase stator windings 68.

  The assist drive unit 26 rotates the sprocket 36 when the pedals 40L and 40R are pushed in the forward direction (forward direction) of the assist bicycle 10, and the pedals 40L and 40R are pushed in a direction opposite to the forward direction. In some cases, the sprocket 36 is not rotated. Specifically, as shown in FIG. 3, the assist drive unit 26 includes a cylindrical member 72 that is inserted into the outer periphery of the crankshaft 38, and a first member provided between the cylindrical member 72 and the housing 48. The bearing 74 includes a second bearing 76 provided between the crankshaft 38 and the casing 48, and a one-way clutch 78 provided between the crankshaft 38 and the cylindrical member 72. The one-way clutch 78 transmits the rotation of the crankshaft 38 to the cylindrical member 72 when the pedals 40L and 40R are wound in the forward direction, and cranks when the pedals 40L and 40R are wound in the direction opposite to the forward direction. The rotation of the shaft 38 is not transmitted to the cylindrical member 72. A spline is formed at the right end of the cylindrical member 72, and the sprocket 36 is attached in a state of being fitted to the spline.

  When the pedals 40L and 40R are turned in the forward direction, the crankshaft 38 is rotated and the cylindrical member 72 is rotated by the one-way clutch 78. As a result, the sprocket 36 rotates. On the other hand, when the pedals 40L and 40R are turned in the direction opposite to the forward direction, the crankshaft 38 rotates, but the cylindrical member 72 does not rotate by the one-way clutch 78. Thereby, even if the pedals 40L and 40R are twisted in the direction opposite to the forward direction, the sprocket 36 does not rotate.

  A magnetostrictive torque sensor 80 that detects the pedaling force torque applied to the crankshaft 38 is disposed on the crankshaft 38. Specifically, a magnetostrictive torque sensor 80 is disposed on the outer periphery of the cylindrical member 72. The magnetostrictive torque sensor 80 includes a detection circuit including two detection coils 82 and 84, and the detection circuit detects a change in inductance of each detection coil 82 and 84 caused by magnetostriction generated when the cylindrical member 72 rotates. The voltage is converted and output to the controller 54. Note that when the pedals 40L and 40R are turned in the reverse direction to the forward direction, the cylindrical member 72 does not rotate, and therefore the pedaling force torque applied to the crankshaft 38 is not detected by the magnetostrictive torque sensor 80.

  The drive shaft 56 of the brushless motor 50 is provided with a magnet holder 88 that holds a magnet 86 and rotates together with the rotation of the rotor 66. Hall ICs 90 for detecting the magnets 86 are provided so as to face the magnets 86, and three Hall ICs 90 are provided (see FIG. 2). The three Hall ICs 90 detect the rotation angle and the number of rotations of the rotor 66. The Hall IC 90 is held by a Hall IC housing 98. The Hall IC housing 98 is attached inside the casing 48 of the assist drive unit 26 by bolts b. Eight magnets 86 are provided along the circumferential direction, and N-pole magnets 86 and S-pole magnets 86 are alternately arranged. The magnet 86 and the Hall IC 90 function as a magnetic pole sensor that detects the rotation angle of the brushless motor 50.

  A space in which the brushless motor 50 and the drive gear 58 are stored is partitioned. A dust seal 110 is provided on the outer circumference of the magnet holder 88, and the dust seal 110 prevents dust and the like from entering the space where the brushless motor 50 is provided from the space where the drive gear 58 is provided. A cover that protects the brushless motor 50 is attached to the casing 48 of the assist drive unit 26 by bolts B along the outer periphery of the brushless motor 50.

  The housing 48 has a partition plate 92 that partitions the space in the housing 48, the drive driver 52, the controller 54, and the magnetostrictive torque sensor 80 are arranged in the same space, and the brushless motor 50 includes a crankshaft 38 is located behind and below 38 and is housed in a space partitioned from the magnetostrictive torque sensor 80. Further, the drive driver 52 and the controller 54 are disposed below the magnetostrictive torque sensor 80.

  The brushless motor 50 and the magnetic pole sensor (the magnet 86 and the Hall IC 90) are disposed on the opposite side of the magnetostrictive torque sensor 80 with respect to the center line 112 in the front-rear direction of the assist bicycle 10. Although the space in which the magnetostrictive torque sensor 80 and the brushless motor are accommodated is partitioned, the magnetostrictive torque sensor 80 and the brushless motor 50 are in close proximity to each other. Although not shown, the drive driver 52 and the controller 54 are fixed to the wall of the casing 48 and are fixed to the left and right wall surfaces facing the center line 112 in the front-rear direction of the assist bicycle 10, respectively. The magnet 48 is disposed on the wall surface of the casing 48 on the magnetostrictive torque sensor 80 side.

  The idler 62 is pivotally supported by the support arm 114, and the pivot 116 pivotally supports the support arm 114 so as to be swingable. The support arm 114 pivotally supported by the pivot 116 is urged in a direction in which the idler 62 presses the chain 44 by a torsion spring.

  A one-way clutch 96 is provided between the driven shaft 94 of the assist sprocket 60 and the drive gear 58. The one-way clutch 96 rotates in the forward direction (the direction in which the assist bicycle 10 moves forward). The rotation is transmitted to the driven shaft 94 only when As a result, only when the rotor 66 of the brushless motor 50 is rotating in the forward direction, the assist sprocket 60 is rotated, and the auxiliary torque generated by the brushless motor 50 is transmitted to the sprocket 46 on the rear wheel WR side via the chain 44. Is done.

  FIG. 4 is a detection circuit diagram of the magnetostrictive torque sensor 80. The magnetostrictive torque sensor 80 is a well-known technique and will be described briefly. The magnetostrictive torque sensor 80 includes resistors 100 and 102 and a differential amplifier 104 in addition to the detection coils 82 and 84. The detection coils 82 and 84 are connected in series via the connection point a, the other end of the detection coil 82 is connected to the connection point b connected to the + terminal of the differential amplifier 104, and the other end of the detection coil 84. Is connected to a connection point c connected to the negative terminal of the differential amplifier 104. The resistors 100 and 102 are connected in series via the connection point d, the other end of the resistor 100 is connected to the connection point b, and the other end of the resistor 102 is connected to the connection point c.

  The differential amplifier 104 amplifies the difference between the two input voltage signals by a constant coefficient and outputs the amplified signal. The voltage signal output from the differential amplifier 104 becomes a detection value of the magnetostrictive torque sensor 80. An application pulse (pulse voltage) with a predetermined period from the controller 54 is input to the connection point a, and the connection point d is grounded. When an applied pulse having a predetermined period is applied from the controller 54 to the magnetostrictive torque sensor 80, a voltage is generated in the detection coils 82 and 84 in accordance with the applied pulse voltage. The voltage generated in the detection coils 82 and 84 varies depending on the change in inductance of the detection coils 82 and 84 caused by magnetostriction.

  FIG. 5 shows a voltage waveform when an applied pulse is supplied from the controller 54 to the magnetostrictive torque sensor 80. A waveform a indicates a waveform of an applied pulse applied to the connection point a, a waveform b indicates a voltage waveform at the connection point b, and a waveform c indicates a voltage waveform at the connection point c. The voltage at the connection point b and the connection point c increases in synchronization with the input of the rectangular application pulse, and the voltage at the connection point b and the connection point c decreases during a period in which the application pulse is not applied. A waveform e is a voltage waveform output from the differential amplifier 104, and is a waveform obtained by subtracting the voltage waveform at the connection point c from the voltage waveform at the connection point b and multiplying by a constant coefficient.

  The controller 54 calculates the torque value based on the detected value of the sampling timing after the lapse of a fixed time after the application pulse is applied. This certain time is the time when the voltage output from the magnetostrictive torque sensor 80 (the voltage output from the differential amplifier 104) becomes the maximum or the time when it exceeds the threshold. The peak timing of the voltage output from the magnetostrictive torque sensor 80 can be adjusted by the detection coils 82 and 84 and the resistors 100 and 102 of the magnetostrictive torque sensor 80. The voltage value output from the differential amplifier 104 is a detection value detected by the magnetostrictive torque sensor 80.

  FIG. 6 is a diagram illustrating the rotation direction of the permanent magnet 64 disposed on the rotor 66. FIG. 7 is a diagram illustrating a U-phase stator coil, a V-phase stator coil, and a W-phase stator coil of the brushless motor. It is a figure which shows the electric current supplied to and the state of the permanent magnet 64 at that time.

  As shown in FIG. 6, four N-pole and S-pole permanent magnets 64 are arranged in the circumferential direction of the rotor, and A is a reference angle. This reference angle A is an angle when the center of the rotor 66 is the origin. The permanent magnet 64 is assumed to rotate clockwise in the plan view of FIG. When the UVW-phase AC current shown in FIG. 7 is supplied to the U-phase stator coil, the V-phase stator coil, and the W-phase stator coil, the magnetic pole at the reference angle A becomes the S pole, and the UVW-phase AC current is supplied. When a half cycle elapses, the magnetic pole at the reference angle A is switched to the N pole. That is, the rotor 66 rotates 45 degrees in a half cycle of the AC current of the UVW phase (electrical angle 180 degrees).

  FIG. 8 is a diagram showing the relationship between the magnet 86 and the detection coils 82 and 84 of the magnetostrictive torque sensor 80. As shown in FIG. 8, in the magnet 86, four N-pole and S-pole magnets are arranged in the circumferential direction, and B is a reference angle. The reference angle B is an angle when the center of the circle formed by the eight magnets 86 (the center of the rotor 66) is the origin. The magnet 86 rotates together with the rotation of the rotor 66. In the present embodiment, the rotor 66 and the magnet 86 rotate clockwise in the plan view of FIG. The three Hall ICs 90 are provided at an electrical angle of 60 degrees (rotation angle of the rotor 66 is 15 degrees). The Hall IC 90 outputs a detection signal (voltage signal) corresponding to the pole of the magnet 86 to the controller 54. At the time of switching between the N pole and the S pole, the detection signal output from the Hall IC 90 changes, so the controller 54 can detect the switching timing of the pole of the magnet 86 from the change in the detection signal.

  In FIG. 8, it is on a line passing through the center of the detection coils 82 and 84 and the center of the circle formed by the eight magnets 86 arranged in the circumferential direction (the center of the rotor 66). Hall IC 90a is provided on the opposite side, and Hall IC 90b and Hall IC 90c are provided at intervals of 15 degrees counterclockwise from Hall IC 90a. Thereby, whenever the magnet 86 rotates 45 degree | times, the controller 54 can detect the switching timing of NS pole 3 times. The controller 54 switches the energization pattern of each UVW-phase stator coil in synchronization with the switching timing of the IC hall or in accordance with the switching timing. The reference angle B is on a line passing through the center of the detection coils 82 and 84 and the center of the circle formed by the eight magnets 86 arranged in the circumferential direction, and on the detection coil 82 and 84 side. Is the position.

  Here, a case where the detection value detected by the magnetostrictive torque sensor 80 is affected by the brushless motor 50 will be described. That is, when the magnetic field and magnetic flux change around the magnetostrictive torque sensor 80, the detection coil 82 and the detection coil 84 are affected by the change. The noise caused by. As a case where the detected value is affected by the magnetostrictive torque sensor 80, first, the PWM pulse supplied to the drive driver 52 after the applied pulse is applied to the connection point a and before the sampling timing arrives. Is turned on and off. Second, the timing at which the poles of the permanent magnet 64 of the brushless motor 50 and the magnet 86 of the magnetic pole sensor are switched coincides with the sampling timing of the magnetostrictive torque sensor 80 within a certain time range. Thirdly, the timing at which the energization pattern of the stator coil of each phase is switched coincides with the sampling timing of the magnetostrictive torque sensor 80 within a certain time range. When the poles of the magnet 86 and the permanent magnet 64 are switched, as shown in FIG. 8, the reference angle B at which the distance between the detection coils 82 and 84 and the magnet 86 is the shortest (position facing the magnetostrictive torque sensor 80 side). Thus, it refers to the time when the pole of the magnet 86 changes, and the time when the pole of the permanent magnet 64 changes at the position where the distance between the detection coils 82 and 84 and the permanent magnet 64 is the shortest. Since the magnet 86 and the permanent magnet 64 are arranged in the circumferential direction around the rotor, the position where the distance between the detection coils 82 and 84 and the permanent magnet 64 is the shortest is the reference angle B.

  Therefore, in the present invention, a detection value with noise is not used for calculation of a torque value, and will be described in detail below.

  FIG. 9 is a time chart showing the voltages of the U-phase stator coil, the V-phase stator coil, and the W-phase stator coil when an alternating current is applied to the stator coil of each phase by the drive driver 52, and the hall It is a figure which shows the switching timing of the pole which the controller 54 detected by IC90.

  When an alternating current (for example, an alternating current as shown in FIG. 7) is supplied to the stator coil of each phase, a voltage is generated in the stator coil of each phase. A positive value is applied when a voltage in a predetermined direction is applied to the stator coil of each phase, and a negative voltage is applied when a voltage is applied in a direction opposite to the predetermined direction. When the stator coil voltage is negative, a negative alternating current is applied. By applying a PWM pulse to the switching element of each phase of the drive driver 52, a voltage as shown in FIG. 9 is generated in the stator coil of each phase. The rotor 66 rotates 45 degrees when the stator coil voltage is negative, and the rotor rotates 45 degrees when the stator coil voltage is positive.

  In the present embodiment, a PWM pulse with a determined duty ratio is applied to the drive driver 52 so that the voltage of the stator coil becomes negative. For example, when the voltage of the U-phase stator coil is negative, the PWM pulse is output to the drive driver 52 so that the voltage of the U-phase stator coil is negative.

  In the present embodiment, a description will be given by taking as an example a PWM pulse output to the drive driver 52 when the voltage of the U-phase stator coil is negative. The period during which the voltage of the U-phase stator coil is negative (a period corresponding to a half cycle of the alternating current) is an electrical angle of 180 degrees, and during this period, the PWM pulse is controlled with a predetermined duty ratio. The half cycle of this alternating current is 1500 μsec, and the PWM pulse cycle is 50 μsec. Therefore, 30 PWM pulses are applied to the drive driver 52 during a period when the voltage of the U-phase stator coil is negative. In addition, three cycles of the PWM pulse are set as one set. Accordingly, 10 sets of PWM pulses are applied to the drive driver 52 during a half-cycle period of the alternating current. The same applies when the voltages of the stator coils of other phases are negative.

  The controller 54 sets the fixed time from when the applied pulse is applied to the magnetostrictive torque sensor 80 to the sampling timing is shorter than ½ of the period of the PWM pulse applied to the drive driver 52, and sets the PWM pulse. The applied pulse is set so as to have at least two sampling timings in a period of a constant period (in the embodiment, three periods of PWM pulses, that is, one set). In the present embodiment, at least two applied pulses are applied during a period of three periods of the PWM pulse.

  FIG. 10 is a flowchart showing the operation of the controller 54 that determines the application timing of the applied pulse, the sampling timing, and the OFF timing of the applied pulse. The controller 54 outputs the PWM pulse to the drive driver 52 (step S1 in FIG. 10). Next, it is determined whether or not the input PWM pulse is one set of PWM pulses (step S2). If it is determined in step S2 that it is the first PWM pulse of one set, an applied pulse is input to the connection point a of the magnetostrictive torque sensor 80 (step S3).

  Next, the first sampling timing is set to a time after a fixed time has elapsed since the first application pulse was applied (step S4). The predetermined time is ½ or less of the period of the PWM pulse. Next, the OFF time of the first applied pulse is set (step S5), and the process returns to step S1. When the OFF timing of the first applied pulse arrives, the controller 54 turns off the applied pulse.

  On the other hand, if it is determined in step S2 that the second PWM pulse has been input, the application timing of the second applied pulse is set at the connection point a of the magnetostrictive torque sensor 80 (step S6). When the set application timing of the second applied pulse arrives, the controller 54 applies the applied pulse to the connection point a of the magnetostrictive torque sensor 80. The timing of applying the second applied pulse is ½ of the period of the PWM pulse, that is, ½ of the period of the second PWM pulse. Next, the second sampling timing is set to a time after a predetermined time has elapsed from the second application pulse application (step S7), and the process returns to step S1.

  If it is determined in step S2 that the third PWM pulse has been input, the OFF timing of the second applied pulse is set (step S8). When the second application pulse OFF timing arrives, the controller 54 turns off the application pulse.

  Next, a detection value selection process is performed for selecting a detection value used for calculating the torque value from among the detection value obtained at the first sampling timing and the detection value obtained at the second sampling timing (step S9). ), The process returns to step S1. This detection value selection process will be described in detail later. The operation shown in the flowchart of FIG. 10 is performed every 50 μsec.

  FIG. 11 is a time chart showing the relationship between applied PWM pulses and applied pulses when the duty ratio is less than 50, and FIG. 12 shows applied PWM pulses and applied when the duty ratio is 50 or more. It is a time chart which shows the relationship of a pulse. 11 and 12, the detection value of the magnetostrictive torque sensor 80 is enlarged in the vertical axis direction for easy viewing. When the first PWM pulse is applied to the drive driver 52 at time t1 (step S1 in FIG. 10), the applied pulse is applied to the connection point a of the magnetostrictive torque sensor 80 at step t2 (step S3). Further, the first sampling timing is set to t3 after a predetermined time has elapsed since the first applied pulse was applied (step S4). t4 is the time when the first applied pulse set in step S5 is OFF. When the second PWM pulse is applied to the drive driver 52 at t5 when 50 μsec has elapsed from t1 (step S1), the time when the second applied pulse is applied is a half cycle of the cycle of the second PWM pulse. The timing is set to t6 (step S6), and the second sampling timing is set to t7 after a predetermined time has elapsed after the second application pulse is applied (step S7). When the third PWM pulse is applied at time t8 when 50 μsec has elapsed from time t5 (step S1), a time t9 at which the second applied pulse is turned off is set (step S8).

  Here, as can be seen from FIG. 11, when the duty ratio of the PWM pulse is less than 50, the PWM pulse is not generated until the first sampling timing comes after the first application pulse is applied. The PWM pulse is not turned on / off (turned on or off) from when the second applied pulse is applied until when the second sampling timing arrives after turning from on to off. As can be seen from FIG. 12, when the duty ratio of the PWM pulse is 50 or more, the PWM pulse is turned on after the first application pulse is applied until the first sampling timing arrives. -The PWM pulse is turned off from on after the second applied pulse is applied until the second sampling timing arrives without turning off. If the PWM pulse is turned on and off between the time when the applied pulse is applied and the time when the sampling timing arrives, noise will be added to the voltages of the detection coils 82 and 84 of the magnetostrictive torque sensor 80, so the duty of the PWM pulse The detection value used for calculating the torque value is switched according to the ratio. That is, when the duty ratio of the PWM pulse is less than 50, the detection value detected at the second sampling timing is used, and when the duty ratio of the PWM pulse is 50 or more, the detection detected at the first sampling timing. Use the value.

  FIG. 13 is a flowchart showing an operation of acquiring the detection value detected by the magnetostrictive torque sensor 80. The controller 54 determines whether or not the PWM pulse applied to the drive driver 52 is one set of PWM pulses (step S11). If it is determined in step S11 that it is the first PWM pulse, the controller 54 determines whether or not the first sampling timing has arrived (step S12). If it is determined in step S12 that the first sampling timing has not arrived, the process stays in step S12 until it arrives.

  If it is determined in step S12 that the first sampling timing has arrived, the controller 54 AD-converts and stores the analog detection value detected by the magnetostrictive torque sensor at the first sampling timing (step S13). At this time, the sampling timing is also recorded together with the detection value. The controller 54 may perform noise filter processing on the AD-converted detection value.

  Next, the controller 54 stores that the detected value stored in step S13 is the detected value detected by the first applied pulse (step S14), and stores the duty ratio of the first PWM pulse ( Step S15) and return to Step S11. As will be described later, the duty ratio is determined using a detection value detected by the magnetostrictive torque sensor 80.

  On the other hand, when determining that it is the second PWM pulse in step S11, the controller 54 determines whether or not the second sampling timing has come (step S16). If it is determined in step S16 that the second sampling timing has not arrived, the process stays in step S16 until it arrives.

  If it is determined in step S16 that the second sampling timing has arrived, the controller 54 AD-converts and stores the analog detection value detected by the magnetostrictive torque sensor at the second sampling timing (step S17). At this time, the sampling timing is also recorded together with the detection value. The controller 54 may perform noise filter processing on the AD-converted detection value.

  Next, the controller 54 stores that the detection value stored in step S17 is the detection value detected by the second applied pulse (step S18), and stores the duty ratio of the second PWM pulse ( Step S19), returning to step S11. If it is determined in step S11 that it is the third PWM pulse, the process directly returns to step S1. The operation shown in the flowchart of FIG. 13 is performed every 50 μsec.

  FIG. 14 is a flowchart showing a calculation operation of the switching timing of the energization pattern for energizing the U-phase stator coil, the V-phase stator coil, and the W-phase stator coil of the brushless motor 50. First, the controller 54 determines whether or not the switching of the poles of the magnet 86 has been detected based on the detection signal detected by the Hall IC 90 (step S21). If it is determined in step S21 that the switching of the poles of the magnet 86 cannot be detected, the process stays in step S21 until it is detected.

  If it is determined in step S21 that the switching of the pole of the magnet 86 has been detected, the controller 54 calculates the switching timing of the energization pattern (step S22). When the energization pattern switching timing is advanced, the energization pattern switching timing is calculated so that the energization pattern switching timing is delayed by an advance angle from the magnet 86 pole switching timing. Note that when the advance angle or the retard angle is not set, the switching timing of the poles of the magnet 86 is set as the switching timing of the energization pattern. In this case, the switching timing of the magnet 86 is synchronized with the switching timing of the energization pattern of the UVW-phase stator coil.

  When the energization pattern switching timing is calculated in step S23, the calculated energization pattern switching timing is stored (step S23).

  9, t11, t13, t15, and t17 indicate the switching timing of the poles of the magnet 86 detected by the Hall IC 90, and t12, t14, t16, and t18 indicate the switching timing of the energization pattern. Here, as described above, since the Hall IC 90 is provided at an electrical angle interval of 60 degrees (15 degrees as the rotation angle of the rotor 66), the switching of the poles of the magnet 86 is detected at an electrical angle interval of 60 degrees. From FIG. 9, the energization pattern switching timings t12, t14, t16, and t18 are switched from the switching timings t12, t14, t16, and t18 after the advance angle has elapsed, and the energization pattern pattern of the UVW-phase stator coil is switched. I understand.

  FIG. 15 is a flowchart showing an energization pattern switching operation. The controller 54 determines whether or not the energization pattern switching timing stored in step S23 of FIG. 14 has arrived (step S31). If it is determined in step S31 that the energization pattern switching timing has not arrived, the process stays in step S31 until it is determined that it has arrived.

  When it is determined in step S31 that the energization pattern switching timing has arrived, the controller 54 performs PWM control on the drive driver 52 to switch the energization pattern (step S32). Specifically, the switching element of the drive driver 52 to which the PWM pulse is applied is changed.

  FIG. 16 is a flowchart showing the storage operation of the switching timing of the poles of the magnet 86 of the magnetic pole sensor and the permanent magnet 64 of the rotor 66. The controller 54 detects the timing at which the pole of the magnet 86 of the magnetic pole sensor is switched at the reference angle B at which the distance from the detection coils 82 and 84 of the magnetostrictive torque sensor 80 is the shortest (step S41). As shown in FIG. 8, the Hall IC 90a is provided on a line passing through the center of the detection coil 82 and the center of the rotor 66 and on the opposite side of the detection coils 82 and 84 (that is, the reference angle B and Since the Hall IC 90a has a phase difference of 180 degrees and the number of the magnets 86 is 8, the controller 54 detects the timing at which the detection signal of the Hall IC 90a changes as the timing at which the pole of the magnet 86 changes. That is, since the pole of the magnet 86 is switched at the reference angle B at the timing when the pole of the magnet 86 is switched at the Hall IC 90a, the timing at which the detection signal of the Hall IC 90a is changed is the timing at which the pole of the magnet 86 is switched.

  Next, the controller 54 stores the timing when the magnet 86 of the magnetic pole sensor is switched (step S42). When the number of the magnets 86 is an odd number such as seven, the timing at which the pole of the magnet 86 is switched at the reference angle B does not coincide with the timing at which the pole of the magnet 86 is switched at the Hall IC 90, so that the Hall ICs 90a, 90b, Based on the timing at which the detection signal of any one of the Hall ICs 90c changes, the phase difference between any one of the Hall ICs 90 and the reference angle B, and the rotational speed of the rotor 66, the magnet 86 at the reference angle B The switching timing of the poles may be predicted.

  Next, the controller 54 detects the timing at which the pole of the permanent magnet 64 of the rotor 66 is switched at the reference angle B that is the shortest distance from the detection coils 82 and 84 of the magnetostrictive torque sensor 80 (step S43). Since the magnet 86 and the rotor 66 of the magnetic pole sensor rotate integrally, the controller 54 can detect the switching timing of the pole of the permanent magnet 64 at the reference angle B based on the detection signal of the Hall IC 90.

  For example, as shown in FIG. 17, when the switching angle of the pole of the magnet 86 is the same as the switching angle of the magnet of the permanent magnet 64, the timing at which the detection signal of the Hall IC 90a changes is the switching timing of the pole of the permanent magnet 64. Can be detected as Further, when the phase of the switching angle of the pole of the magnet 86 and the switching angle of the pole of the permanent magnet 64 are shifted, the timing at which the detection signal of the Hall IC 90a changes and the phase difference (the switching angle of the pole of the magnet 86). And the phase difference between the poles of the permanent magnet 64) and the rotational speed of the rotor 66, the timing at which the permanent magnet 64 switches at the reference angle B can be predicted and detected.

  Next, the controller 54 stores the timing at which the permanent magnet 64 of the rotor 66 is switched at the reference angle B (step S44). Each time the rotor 66 rotates 45 degrees, the poles of the permanent magnet 64 and the magnet 86 are switched once each at the reference angle B (two times in total), but the switching angle of the pole of the permanent magnet 64 and the pole of the magnet 86 are switched. When the phase of the switching angle is the same, the poles are switched once by rotating the rotor 66 by 45 degrees.

  FIG. 18 is a flowchart showing an operation for determining the duty ratio of the PWM pulse applied to the drive driver 52. First, the controller 54 calculates a torque value (stepping force torque value) of the pedaling force torque from the detection values selected by the detection value selection process in step S9 in FIG. 10 among the detection values detected by the magnetostrictive torque sensor 80. (Step S51). Next, the vehicle speed acquired from a vehicle speed sensor (not shown) is acquired (step S52), and the assist ratio is determined according to the acquired vehicle speed (step S53).

  Next, a torque value (auxiliary torque value) of the auxiliary torque is calculated from the determined assist ratio and the pedaling force torque value calculated in step S41 (step S54). Next, the duty ratio of the PWM pulse output to the drive driver 52 is determined from the calculated auxiliary torque value (step S55). That is, the duty ratio of the drive driver 52 is determined so that the rotor 66 of the brushless motor 50 generates the torque of the calculated auxiliary torque value.

  Next, the drive driver 52 is subjected to PWM control with the determined duty ratio (step S56). That is, the switching element of the drive driver 52 is driven with the PWM pulse having the determined duty ratio. Next, it is determined whether or not a predetermined time (for example, a time between 1 msec to 10 msec) has elapsed since the PWM pulse was output to the drive driver 52 with the determined duty (step S57). If it is determined in step S57 that the predetermined time has not elapsed, the process stays in step S57 until the predetermined time has elapsed. If it is determined that the predetermined time has elapsed, the process returns to step S51.

  FIG. 19 is a sub-flowchart showing the operation of the detection value selection process in step S9 of FIG. The controller 54 determines whether or not the duty ratio of the first PWM pulse in the set stored in step S15 of FIG. 13 is equal to or greater than a predetermined duty ratio (step S71). The predetermined duty ratio is 50%. The predetermined duty ratio may be a duty ratio of 40% to 50%.

  If it is determined in step S71 that the duty ratio of the first PWM pulse is greater than or equal to the predetermined duty ratio, the controller 54 determines that the detection value detected at the first sampling timing has not received noise due to the influence of the PWM pulse. to decide. The controller 54 determines that the first sampling timing (sampling timing recorded in step S13 in FIG. 13) is the energization pattern switching timing stored in step S23 in FIG. 14 and the steps S42 and 44 in FIG. It is determined whether or not at least one of the stored pole switching timings coincides within a certain time range (step S72). That is, it is determined whether or not the detected value is detected at the switching timing of the energization pattern and the switching timing of the poles of the permanent magnet 64 or the magnet 86. That is, in step S72, it is determined whether or not the detection value detected at the first sampling timing has received noise due to switching of the energization pattern, switching of the pole of the magnet 86, or switching of the pole of the permanent magnet 64. Yes.

  If it is determined in step S72 that the values do not match within a certain time range, the controller 54 determines that the detection value detected at the first sampling timing has not received noise, and the first sampling timing. The detection value detected in (1) is selected as a detection value used for calculation of the torque value in step S51 of FIG. 18 (step S73).

  On the other hand, if it is determined in step S71 that the duty ratio of the first PWM pulse is not greater than or equal to the predetermined duty ratio, the controller 54 determines whether or not the duty ratio of the second PWM pulse is less than the predetermined duty ratio ( Step S74). That is, in step S74, since the detection value detected at the first sampling timing has received noise due to the influence of the PWM pulse, the detection value detected at the second sampling timing has been subjected to noise due to the influence of the PWM pulse. Judging whether or not it is received.

  If it is determined in step S74 that the duty ratio of the second PWM pulse is less than the predetermined duty ratio, the controller 54 determines that the detection value detected at the second sampling timing has not received noise due to the influence of the PWM pulse. to decide. Then, the controller 54 determines that the second sampling timing (sampling timing recorded in step S17 in FIG. 13) is the energization pattern switching timing stored in step S23 in FIG. 14 and the steps S42 and 44 in FIG. It is determined whether or not at least one of the stored pole switching timings coincides within a certain time range (step S75). That is, it is determined whether or not the detected value is detected at the switching timing of the energization pattern and the switching timing of the poles of the permanent magnet 64 or the magnet 86. That is, in step S75, it is determined whether or not the detection value detected at the second sampling timing has received noise due to switching of the energization pattern, switching of the pole of the magnet 86, or switching of the pole of the permanent magnet 64. Yes.

  If it is determined in step S75 that they do not match within a certain time range, the controller 54 determines that the detection value detected at the second sampling timing has not received noise, and the second sampling timing. The detection value detected in (1) is selected as the detection used for calculating the torque value in step S51 of FIG. 18 (step S76).

  Step S72, if it is determined that the first sampling timing matches one of the energization pattern switching timing and the pole switching timing within a certain time range, the second PWM pulse is determined in Step S74. If it is determined that the duty ratio is not less than the predetermined duty ratio, the second sampling timing is within a certain time and one of the energization pattern switching timing and the pole switching timing in step S74. If it is determined that they match, the detection value selection process is terminated without selecting the detection value. In this case, noise is added to the detection values detected at the first sampling timing and the second sampling timing.

  As shown in FIG. 9, when only the U-phase stator coil is considered, 30 PWM pulses are output to the drive driver 52 during a period in which the voltage of the U-phase stator coil is negative (electrical angle 180 degrees). . In addition, a detection value that is not affected by noise due to the influence of the PWM pulse can be obtained once every 3 pulses (one set), so that a detection value that is not affected by the influence of the PWM pulse during a half cycle is 10 times. Obtainable. In addition, the switching timing of the energization pattern is 4 times (or 3 times if not advanced or retarded), and the switching timing of the poles of the permanent magnet 64 and the magnet 86 is 1 each, that is, a total of 2 times (note that When the phase of the switching angle between the poles of the permanent magnet 64 and the magnet 86 is the same, the total is once). Therefore, the detection value that does not receive the noise due to the influence of the PWM pulse is 10 times. Even if the noise received by switching the energization pattern and the noise received by switching the poles of the permanent magnet 64 and the magnet 86 are taken into account, the electrical angle 180 ( With the rotation angle of the rotor 66 being 45 degrees, a detection value that is not affected by noise can be obtained four times. Thus, since the torque value is calculated using the detection value that is not affected by the noise caused by the PWM pulse, the detection accuracy of the torque value can be improved, and the actuator system can be reduced in size and cost. Can do.

  In the embodiment described above, all of noise due to PWM pulses, noise due to switching of the poles of the permanent magnet 64 of the rotor 66, noise due to switching of the poles of the magnet 86 of the magnetic pole sensor, and noise due to switching of the energization pattern are considered. Although the detection value used for calculating the torque value is selected, the detection value used for calculating the torque value may be selected in consideration of any one of the noises.

  In the above-described embodiment, three cycles of the PWM pulse are set as one set, but one set may be two cycles or four cycles or more. When one set is an even period, if the period of the applied pulse to be applied is constant, the PWM pulse will be turned on / off before a certain time elapses after all the applied pulses are applied. The period of the applied pulse must be varied. Therefore, it is preferable to set one odd period. In addition, the application pulse is applied twice in one set period, but may be two or more. The number of times of applying the application pulse in one set period is appropriately changed depending on how many periods of the PWM pulse are set as one set. In short, based on the duty ratio of the PWM pulse, the sampling timing at which a fixed time has passed without the PWM pulse being turned on and off after the application pulse is applied is determined as the sampling timing used for calculating the torque value, The torque value may be calculated from the detected value detected at the determined sampling timing.

  When an internal combustion engine is provided instead of the brushless motor 50, the detection value detected by the magnetostrictive torque sensor 80 at the ignition timing of the internal combustion engine may not be used for the calculation of the torque value. That is, if the ignition timing of the internal combustion engine and the sampling timing coincide within a certain time range, the detection value detected by the magnetostrictive torque sensor 80 at the sampling timing is not used for calculation of the torque value. Also good. In this case, although not shown, the internal combustion engine is provided with a spark plug and a driver having an ignition coil and a switching element for driving the spark plug, and an energization command for the controller 54 to ignite the driver's command. The detection value detected at the timing applied to the switching element is not used for the calculation of the torque value.

  Further, a magnetic shield may be provided around the magnetostrictive torque sensor 80 so as not to receive a change in magnetic field and magnetic flux from the brushless motor 50, and a magnetic field and magnetic flux due to PWM control of the drive driver 52. In this case, a magnetic shield with a low degree of shielding the magnetic action may be used. Thereby, the detection accuracy of the torque value can be further improved.

  Further, when the duty ratio determined in step S55 in FIG. 18 varies in the vicinity of the predetermined duty ratio, a wrapping area may be provided. In this case, when the determined duty ratio is in the overlapping region, the torque value is calculated using the detection value detected at one of the first sampling timing and the second sampling timing.

  As mentioned above, although this invention was demonstrated using suitable embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the description of the scope of claims that embodiments with such changes or improvements can be included in the technical scope of the present invention. In addition, the reference numerals in parentheses described in the claims are appended to the reference numerals in the accompanying drawings for easy understanding of the present invention. It is not construed as limiting.

DESCRIPTION OF SYMBOLS 10 ... Assist bicycle 26 ... Assist drive unit 36, 46 ... Sprocket 38 ... Crankshaft 44 ... Chain 48 ... Housing 50 ... Brushless motor 52 ... Drive driver 54 ... Controller 58 ... Drive gear 60 ... Assist sprocket 64 ... Permanent magnet 66 ... Rotor 68 ... Stator winding 70 ... Stator 80 ... Magnetostrictive torque sensors 82, 84 ... Detection coil 86 ... Magnets 90, 90a to 90c ... Hall IC

Claims (5)

A magnetostrictive torque sensor (80);
A brushless motor (50);
A drive driver (52) for driving the brushless motor (50);
An application pulse is periodically applied to the magnetostrictive torque sensor (80), and a torque value is calculated from a detection value detected by the magnetostrictive torque sensor (80) at a sampling timing after the elapse of a predetermined time from the application, Control means (54) for controlling the drive of the brushless motor (50) by PWM control of the drive driver (52) according to the calculated torque value;
An actuator system comprising:
The control means (54)
The fixed time is set to be shorter than 1/2 of the period of the PWM pulse applied to the drive driver (52) by the PWM control, and at least two sampling timings are set during a constant period of the PWM pulse. Set the applied pulse to provide
The detection value detected by the magnetostrictive torque sensor (80) at the first sampling timing after the application of the first PWM pulse among the PWM pulses applied in the period of the predetermined number of cycles is sampled. 1 sampling timing and a second sampling timing for sampling the detected value detected by the magnetostrictive torque sensor (80) at the first sampling timing after a period of ½ of the predetermined number of cycles has elapsed. And
The control means (54) calculates the torque value using the detection value detected at the first sampling timing when the duty ratio of the PWM pulse is equal to or greater than a predetermined duty ratio, and calculates the duty of the PWM pulse. When the ratio is less than the predetermined duty ratio, the torque value is calculated using the detection value detected at the second sampling timing. The actuator system according to claim 1,
The certain number of cycles is an odd number of 3 or more,
The control unit (54) sets the fixed number of cycles as one set, and applies the applied pulse to the magnetostrictive torque sensor at least twice during the set period. The actuator system according to claim 1 or 2,
The magnetostrictive torque sensor (80) and the brushless motor (50) are integrally formed as an actuator unit (26), and the magnetostrictive torque sensor (80) and the brushless motor (50) are close to each other. The actuator system is characterized in that the actuator unit (26) is configured as an assist unit (26) of the assist bicycle (10). The actuator system according to claim 3, wherein
The actuator system includes a crankshaft (38) to which torque is provided by a driver provided in the assist bicycle (10), and transmits torque applied to the crankshaft (38) to a rear wheel to transmit the rear wheel. A drive system mechanism for driving
The assist unit (26) is an assist drive unit (26) that transmits the drive force of the brushless motor (50) to the drive system mechanism, and includes the crankshaft (38) and the magnetostrictive torque sensor (80). The brushless motor (50), the drive driver (52), and the control means (54) are integrally held, and the magnetostrictive torque sensor (80) is disposed on the crankshaft (38). The drive driver (52) and the control means (54) are disposed in the same space below the magnetostrictive torque sensor (80), and the brushless motor (50) is connected to the crankshaft (38). An actuator system characterized in that the actuator system is housed in a space partitioned from the magnetostrictive torque sensor (80). The actuator system according to claim 4,
The drive driver (52) and the control means (54) are fixed to the case (48) wall of the assist drive unit (26) in the same space, and the front-rear direction of the assist bicycle (10). And the control means (54) is arranged on the wall surface of the case (48) on the magnetostrictive torque sensor (80) side. Actuator system.

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