JP6510942B2 - Brush motor - Google Patents

Description

  The present invention relates to a brush motor used in a wiper device for wiping a windshield of a vehicle.

  Conventionally, a brush motor is used as a motive power source of a wiper device of a vehicle (Patent Document 1, Patent Document 2). In recent years, the number of poles of a brush motor used in a wiper device has been advanced. When the brush motor has multiple poles, the rotation of the brush motor becomes smooth and the vibrations and the like accompanying the rotation are reduced, so the noise of the wiper device can be reduced. In addition, when the number of poles of the brush motor is increased, high torque can be generated at low rotation, so that the brush motor can be reduced in size and weight.

  In addition, when the brush motor has multiple poles, the order of torque ripple increases due to the number of poles and the like, and the amplitude component of the torque ripple decreases, so that the vibration and noise of the brush motor can be reduced. On the other hand, increasing the number of torque ripples due to the increase in the number of poles of the brush motor may increase the high frequency component of the operation noise of the brush motor and may cause the tone to deteriorate. Therefore, conventionally, so-called skew is given to the slot of the armature that accommodates the winding of the brush motor, and the torque ripple of the brush motor is reduced by relaxing the rise of the current induced in the winding when crossing the magnetic field. It is intended to reduce vibration and noise resulting from this torque ripple.

JP 2007-143278 A JP, 2009-262726, A

  However, according to the so-called skew described above, the processing of the armature slot in the brush motor is complicated, and the work of incorporating the winding in the slot is also complicated, which increases the manufacturing cost of the brush motor. Therefore, so-called measures against vibration and noise due to skew can be an obstacle in reducing the size and weight by making the brush motor multipolar.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a brush motor capable of achieving multipolarization and reduction in size and weight while reducing vibration and noise.

The brush motor according to the present invention is a multi-pole brush motor that is used in a wiper device of a vehicle and has four or more magnetic poles for generating a rotational force in one direction, and a rotary armature having a pressure equalizing line; a commutator provided to the armature, a first and a brush and a second brush in contact with the commutator, a first circuit connected to said first brush and the second brush, one end Is connected to the first circuit, and the voltage of the power supply is applied between the first brush and the second brush via the first circuit in conjunction with an operation switch provided on the vehicle. , And a voltage signal in the second circuit and the third circuit, and the first brush and the second circuit are detected based on the detected voltage signal . Select the duty of the voltage pulse to be applied between the A duty control unit; a PWM signal generation unit that outputs a PWM signal that is a pulse train of the duty according to a selected duty supplied from the duty control unit; and the first brush and the second brush A drive connected between any one of the power supply and the ground, turned on and off by the PWM signal, and applying the voltage of the power supply as the voltage pulse between the first brush and the second brush A transistor, and a current detection element for detecting a current value of a current flowing through the drive transistor, wherein the duty control unit reduces the amplitude of the torque ripple of the current detected by the current detection element, and is preset It is particularly preferable to control the duty to adjust the current flowing through the brush motor so as to converge on a target current value. To.
The brush motor according to the present invention is characterized by further comprising a diode provided in only one of the second circuit and the third circuit.

  In the brush motor according to the invention, the duty control unit sets, as the target current value, an average current value which is an average value of the current flowing through the drive transistor detected by the current detection element over a predetermined period, The duty is controlled within a predetermined range based on a value to limit the current flowing through the brush motor.

  In the brush motor according to the invention, the duty control unit sets a rated current of the brush motor as the target current value.

  The brush motor according to the present invention further includes an overcurrent detection unit that determines whether the current value detected by the current detection element exceeds a preset current value, and the duty control unit is configured to When the current value detected by the detection element exceeds the set current value, clocking is started, and the set time set corresponding to the increase in temperature of the brush motor due to the flow of the set current value is set The duty of the PWM signal may be set as a duty at which the brush motor is stopped when it is detected that a timed time in which the current value exceeds the current value flows is exceeded.

  In the brush motor according to the present invention, the brush motor is a brush motor used in a wiper device of a vehicle, and the duty control unit controls the wiper in wiping the windshield according to a desired specification of load torque of the brush motor. It is characterized in that the set value of the duty of the PWM signal at the time of low speed operation and at the time of high speed operation is changed.

  As described above, according to the present invention, it is possible to change the rotational speed without switching the brush from the low speed to the high speed, and to provide a brush motor that achieves multipolarization, size reduction and weight reduction. Can.

It is an outline view of a brush motor by a 1st embodiment of the present invention. It is a figure which shows an example of a part structure, and is a detail view of a brush periphery. It is a block diagram showing an example of composition of a brush motor by a 1st embodiment of the present invention. It is a block diagram which shows the structural example of the duty control part 1201 in 1st Embodiment of this invention. It is a flowchart for demonstrating the operation example of the brush motor by the 1st Embodiment of this invention. It is a figure for demonstrating the overheating | superheat prevention process in the operation example of the brush motor 100 by the 1st Embodiment of this invention. It is a figure for demonstrating the overheating | superheat prevention process in the operation example of the brush motor 100 by the 1st Embodiment of this invention. It is a figure for demonstrating the overheating | superheat prevention process in the operation example of the brush motor 100 by the 1st Embodiment of this invention. FIG. 16 is a diagram showing a configuration example of a set current value table indicating a relationship between a set current value stored in a storage unit in the duty control unit 1201 and a set time corresponding to the set current value. It is a flowchart which shows the operation example of the torque ripple reduction process in the operation example of the brush motor 100 by 1st Embodiment of this invention. It is a wave form diagram for explaining the torque ripple reduction processing in the operation example of the brush motor 100 by a 1st embodiment of the present invention. FIG. 7 is a detailed waveform diagram for illustrating the details of the torque ripple reduction process in the operation example of the brush motor 100 according to the first embodiment of the present invention. It is a figure for demonstrating the 1st modification of the torque ripple reduction process in the operation example of the brush motor 100 by 1st Embodiment of this invention. It is a flowchart of the 1st modification of the torque ripple reduction process in the operation example of the brush motor 100 by 1st Embodiment of this invention. It is a wave form diagram for explaining the 1st modification of torque ripple reduction processing in the example of operation of brush motor 100 by a 1st embodiment of the present invention. FIG. 17 is a diagram showing another example in which each of the duty control unit 1201 and the PWM signal generation unit 1202 in the control board 120 is configured using a microcomputer. FIG. 17 is a diagram showing another example in which each of the duty control unit 1201 and the PWM signal generation unit 1202 in the control board 120 is configured using a microcomputer. It is a figure which shows the example of arrangement | positioning of the control board with which the brush motor by 1st Embodiment of this invention was equipped, (A) shows a 1st example of arrangement, (B) shows a 2nd example of arrangement, (C) shows a third arrangement example, and (D) shows a fourth arrangement example. It is a side view showing arrangement of control board 120 with which brush motor 100B by modification of a 1st embodiment of the present invention was equipped. It is a detailed view of arrangement of control board 120 with which brush motor 100B by modification of a 1st embodiment of the present invention was equipped.

FIG. 1 is an external view of a brush motor 100 according to a first embodiment of the present invention.
The brush motor 100 is a multipolar motor having four or more magnetic poles that rotate in one direction (rotate in one direction). In the first embodiment, the brush motor 100 is, for example, a multipole, for example, a direct current motor having four poles, for generating a rotational force serving as a motive power of a front wiper device of a vehicle. However, the brush motor 100 is optional as long as it is a multipolar direct current motor, and its application is not limited to the front wiper device of a vehicle, and can be used to generate power of any device.

  In FIG. 1, the brush motor 100 includes a motor unit M and a reduction mechanism unit G. The motor unit M incorporates a motor main body 110 that generates a rotational force in one direction. In the housing portion MH of the motor portion M, a field portion (not shown) fixed to the housing portion MH as the motor body portion 110, a rotary armature (not shown) provided with a commutator, and the commutator A brush (not shown) arranged to be in contact is accommodated. In the first embodiment, the rotary armature of the motor main body 110 has a so-called pressure equalizing line, which reduces the number of brushes in contact with the commutator of the rotary armature. The brush is reduced by providing a pressure equalizing line on the rotary armature, and the rotation of the rotary armature of the motor main body 110 is controlled in the vacant area where the reduced brush is disposed (the brush may be disposed). A control board 120 (see FIG. 2) is disposed. The details will be described later.

  The speed reduction mechanism G is for reducing the number of rotations of the rotary armature of the motor main body 110 to a desired number of rotations. In the housing portion GH of the reduction gear mechanism portion G, a worm gear coupled to the rotation shaft (shaft of the rotary armature) of the motor main body portion 110, a worm wheel gear coupled to the worm gear, and the like are accommodated. The rotation decelerated by the reduction gear mechanism G is taken out from the output shaft Q extended from the reduction gear mechanism G. Although not shown in FIG. 1, the output shaft Q reciprocates for the wiper (sometimes referred to as a wiper blade) to wipe the windshield in one direction generated by the motor main body 110. A link mechanism or the like for converting into two-direction rotation in the forward direction (for example, clockwise direction) and the reverse direction (for example, counterclockwise direction) corresponding to the movement is attached.

  In the internal structure of the brush motor 100 according to the first embodiment of the present invention (FIG. 17 described later), the annular brush holder 110H incorporated in the housing portion MH of the motor portion M has an inner side of its hole. Two brushes 111A and 111B are disposed as brushes in contact with the commutator of the rotary armature of the motor main body 110 located at the position of the motor. In the case of four poles, these two brushes 111A and 111B are disposed at positions different by 90 degrees in mechanical angle. This mechanical angle is arbitrarily set in accordance with the number of poles of the brush motor 100.

FIG. 2 is a block diagram showing a configuration example of the brush motor 100 according to the first embodiment of the present invention, and shows elements involved in the rotation control of the rotary armature of the motor main body 110. As shown in FIG.
The brush motor 100 includes a control substrate 120, a current detection element 130, a diode 141, a diode 143, and a relay plate 150 as elements for controlling the rotation of the rotary armature of the motor main body 110.

  The control substrate 120 is an element for generating a voltage applied between the brush 111A and the brush 111B shown in FIG. 17 described later, and is a main component for controlling the rotation of the rotating armature of the motor main body 110. It is an element. The control board 120 is provided with a high-speed brush saved by performing PWM control described later and a brush saved by providing a pressure-equalizing line in the rotary armature inside the housing portion MH of the motor portion M. It is arranged to be located in the area which was being The details will be described later.

  The control board 120 performs a process related to duty control of a PWM signal used in PWM (Pulse Width Modulation) control described later for switching the rotational speed of the brush motor 100 according to the operating speed of the wiper device (hereinafter, “duty control process” To carry out). In the duty control process, when the operation speed of the wiper device is low, the control substrate 120 reduces the duty of the PWM signal to reduce the voltage applied to the motor main body 110. Conversely, when the operating speed of the wiper device is high, the control board 120 increases the voltage applied to the motor body 110 by increasing the duty of the PWM signal.

  Further, the control board 120 carries out a process (hereinafter, referred to as an overheat preventing process) related to control for preventing the overheat due to the overcurrent of the current driving the brush motor 100. In the overheat prevention processing, when the current value detected by the current detection element 130 exceeds the set current value indicating the over current and exceeds the preset set time, the control board 120 detects a difference between the brush 111A and the brush 111B. The duty of a PWM signal (described later) for supplying a voltage applied between is set to 0. As a result, the control board 120 sets the current value of the current flowing to the rotary armature of the motor body 110 to 0, and prevents the brush motor 100 from overheating due to the overcurrent. The set current value is a limit load current which is an upper limit of an allowable current of a load (not shown) connected to the brush motor 100 or a restraining current of the brush motor 100 (motor main body 110). However, the present invention is not limited to this example, and the predetermined current value can be set arbitrarily. For example, the brush motor is continuously supplied with a current of a current value that causes an overcurrent, and the time exceeding the maximum temperature in the specification of the brush motor is measured, and the time for which this time is allowed to have a margin is provided. Set as the above set time.

Further, the control board 120 performs a process related to control for reducing the torque ripple of the brush motor 100 (hereinafter, referred to as “torque ripple reduction process”). In the torque ripple reduction process, the control substrate 120 obtains the average value of the torque ripple (including the torque ripple based on the order unique to the brush motor 100) which is superimposed on the current detected by the current detection element 130. Then, the control substrate 120 changes the excitation current flowing between the brushes 111A and 111B, that is, the motor current flowing to the motor main body 110 so as to converge to the target current value given by the obtained average value. The order specific to the brush motor 100 is an element that is physically determined according to the structure such as the number of poles of the brush motor 100, for example.
Details of each of the duty control process, the overheat prevention process, and the torque ripple reduction process will be described later.

  The current detection element 130 is an element for detecting the current value of the current flowing through the motor main body 110 of the brush motor 100 (that is, the current value of the current flowing through the drive transistor 1204 described later). The current flowing to the rotating armature 110 is detected. In the example of FIG. 10 described later, it is disposed on the current path between the motor main body 110 and the connection point of the low speed operating voltage signal VL and the cathode of the diode 143. However, the present invention is not limited to this example, and the current detection element 130 may be provided on the path of the current supplied to the rotary armature of the motor main body 110. The current detection element 130 may be, for example, any current sensor such as a current sensor using a voltage drop of a resistor, a current sensor using a Hall effect, or the like. A detection signal of the current detection element 130 is input to an overcurrent detection unit 1205 (described later).

  The diode 141 is an element for protecting the motor main body 110 by consuming energy generated when stopping the rotation of the motor main body 110. The wiring of the low speed operating voltage signal VL and the diode 143 combine the low speed operating voltage signal VL and the high speed operating voltage signal VH supplied in conjunction with the operation switch of the front wiper device to supply the power of the motor body 110. It is an element for Here, the high-speed operating voltage signal VH is a voltage signal indicating that the wiper of the front wiper device is operated at high speed. The low speed operating voltage signal VL is a voltage signal indicating that the wiper of the front wiper device is operated at low speed. Each of the high-speed operating voltage signal VH and the low-speed operating voltage signal VL is supplied from an external circuit of the operation switch in the front wiper device to a duty control unit 1201 of the control board 102 described later according to the state of the operation switch. Be done.

  The relay plate 150 is an element for obtaining the timing of the start point and the end point of the reciprocating motion of the wiper blade of the front wiper device. The relay plate 150 is provided inside the housing portion GH of the reduction gear mechanism G, and rotates in conjunction with the operation of the motor main portion 110. Here, the brake contact B is a contact that generates a timing for braking the front wiper device. The start contact S is a contact that generates timing for operating the front wiper device. The brake contact B and the start contact S are electrically connected to the ground E according to the rotation angle of the motor body 110. Therefore, the timing of braking and the timing of operation of the front wiper device can be grasped from the timing at which each contact is at the ground potential. The relay plate 150 is an element that can be realized using a known technique.

The control board 120 will be described in detail. The control substrate 120 includes a duty control unit 1201, a pulse width modulation (PWM) signal generation unit 1202, a drive unit 1203, a drive transistor (FET) 1204, and an overcurrent detection unit 1205. Among them, the duty control unit 1201, the PWM signal generation unit 1202, the drive unit 1203, and the overcurrent detection unit 1205 constitute a PWM control unit (without reference numeral) that performs PWM control of the drive transistor 1204. Here, in the control board 120, each of the duty control unit 1201, the PWM signal generation unit 1202 and the overcurrent detection unit 1205 is used as an element of generation of a PWM signal for driving the brush motor 100 by a program using the microcomputer 1208. Configure.
The PWM signal generation unit 1202 changes the duty (duty ratio, ratio of H level in pulse cycle) of the PWM signal for performing PWM control of the drive transistor 1204, to thereby determine the rotational speed of the rotating armature of the motor main body 110. To change the operating speed of the front wiper device.

In this embodiment, the operation speed of the wiper of the front wiper device will be described in the case of two stages of high speed operation and low speed operation.
When the high speed operation voltage signal VH is input, the duty control unit 1201 constituting the above-mentioned PWM control unit is a PWM signal that causes the duty of the PWM signal supplied to the gate of the drive transistor 1204 to be the duty of high speed operation. It is output to the generation unit 1202. On the other hand, when the low speed operation voltage signal VL is input, the duty control unit 1201 sends a control signal to the PWM signal generation unit 1202 to use the duty of the PWM signal supplied to the gate of the drive transistor 1204 as the duty for low speed operation. Output.

The PWM signal generation unit 1202 constituting the PWM control unit generates a PWM signal which is a pulse train of pulses of the high-speed operation duty set in advance when the control signal to be the high-speed operation duty is supplied. Output to the unit 1203. In addition, when the control signal to set the duty of the low speed operation is supplied, the PWM signal generation unit 1202 generates a PWM signal of the duty of the low speed operation set in advance and outputs the PWM signal to the drive unit 1203.
The drive unit 1203 constituting the PWM control unit performs power amplification of the pulse in the PWM signal supplied from the PWM signal generation unit 1202, and outputs the power to the drive transistor 1204. In the first embodiment, the drive transistor 1204 is driven to the on state in the high level period of the pulse in the PWM signal, and the drive transistor 1204 is driven to the off state in the low level period of the pulse in the PWM signal. Ru.

  The duty of the PWM signal is set in accordance with the characteristic requirements of the motor body 110. In the first embodiment, the duty of the PWM signal is set to 100% when the motor body 110 is operated at high speed for convenience of description, and the duty of the PWM signal is operated when the motor body 110 is operated at low speed. Is set to 70 percent, but is not limited to this example, and the duty of the PWM signal may be set arbitrarily. That is, in the present embodiment, the duty corresponds to the characteristics of each of the motor main body 110 so that the current for setting the operation speed to either the high speed operation or the low speed operation is applied to the motor main body 110. And set in advance.

  The drive transistor 1204 is an element for generating a voltage applied via a brush to the commutator of the rotary armature of the motor main body 110 to energize the winding of the rotary armature. In the first embodiment, the drive transistor 1204 is an n-channel power FET (Field Effective Transistor). Further, instead of the n-channel power FET, a bipolar transistor may be used as the drive transistor 1204. The driving transistor 1204 is connected between the brush 111A provided on the motor main body 110 and the ground E. Specifically, the source of the drive transistor 1204 is connected to the ground E of the vehicle body or the like, and the drain is connected to the brush 111A of the motor main body 110 through the current detection element 130. The drive transistor 1204 receives the PWM signal from the PWM signal generation unit 1202 through the drive unit 1203 to the gate. The drive transistor 1204 is provided with a so-called body diode 1204 a.

  The drive transistor 1204 may be connected in series between the other brush 111B of the motor body 110 and the connection point of the low speed operation voltage signal VL and the cathode of the diode 143. The drain of the driving transistor 1204 is connected to the anode of the diode 141. The cathode of the diode 141 is connected to the brush 111 B of the motor body 110. In the motor body 110, the brush 111B is connected to (a connection point of) the wiring of the low-speed operating voltage signal VL and the cathode of the diode 143. The low speed operating voltage signal VL is supplied to the anode for the wiring of the low speed operating voltage signal VL. The diode 143 is supplied at its anode with a high-speed operating voltage signal VH. Further, in the present embodiment, since the reciprocation of the wiper is performed by the link mechanism, the brush motor 100 is designed to generate a rotational force in only one direction (rotate in only one direction), and for controlling the rotational speed. It is sufficient to provide one drive transistor 1204, and the number of drive transistors for driving the brush motor 100 to rotate is minimized.

  The overcurrent detection unit 1205 constituting the control board 120 detects whether or not the current value of the current flowing to the motor main body 110 is the overcurrent value based on the current value detected by the current detection element 130. It is an element for Here, the overcurrent is a current exceeding the limit load current of the motor body 110 (the current flowing to the rotating armature when the maximum load is applied as the load of the motor body 110) or the restraint of the motor body 110 The current has a current value equal to or higher than the current (the current flowing to the rotating armature when the rotation of the motor main body 110 is restrained). However, the present invention is not limited to this example, and the definition of overcurrent can be made arbitrarily. When the current value of the current detected by the current detection element 130 exceeds the set current value indicating the over current, the over current detection unit 1205 detects the over current flowing to the motor main body 110 or the over current Determine if there is an occurrence.

  The duty control unit 1201 is applied between the brush 111A and the brush 111B when the predetermined time set in accordance with the predetermined current value has elapsed from the time when the overcurrent detection unit 1205 detects the overcurrent. The duty of the PWM signal that controls the voltage is 0. In other words, when the current detected by the current detection element 130 exceeds the predetermined current value and the predetermined time has elapsed, the duty control unit 1201 causes the brush motor 100 to go before the maximum temperature of the specification is exceeded. The duty of the PWM signal for controlling the voltage applied between the brush 111A and the brush 111B is set to 0, the operation of the brush motor 100 is stopped, and the heating of the brush motor 100 due to the overcurrent is suppressed.

  Here, the duty control unit 1201 includes an energization time measurement counter 1201 a for measuring a time in which the state in which the overcurrent flows in the motor main body 110 continues (hereinafter referred to as “overcurrent conduction time”). The duty control unit 1201 controls the voltage applied between the brush 111A and the brush 111B when the over-current conduction time measured by the counter value of the conduction time measurement counter 1201a exceeds the set time. The duty is set to 0, and the operation of the brush motor 100 is stopped. At this time, the duty may not be 0 but may be a duty at which the operation of the brush motor 100 is stopped.

FIG. 3 is a block diagram showing a configuration example of the duty control unit 1201 in the first embodiment of the present invention.
Note that FIG. 3 shows only the components related to the torque ripple reduction processing among the components of the duty control unit 1201, and the components related to the duty control processing and the overheat prevention processing (for example, the power on time measurement counter 1201a) are omitted. It is done. The duty control unit 1201 in FIG. 3 includes a target current setting unit 12011, a subtractor 12012, and a current control unit 12013.

  The target current setting unit 12011 is for setting a target current value IT used in the torque ripple reduction process. The target current setting unit 12011 sets an average current value, which is an average value of the motor current IM detected by the current detection element 130 over a predetermined fixed period, as a target current value IT. The average value of the motor current IM is an amount corresponding to the average value of the motor current (the current serving as the excitation current of the motor main body 110) on which the torque ripple flowing in the brush motor 100 detected by the current detection element 130 is superimposed. .

  In the torque ripple reduction process, under PI control by the current control unit 12013, a motor current flowing through the brush motor 100 detected by the current detection element 130 is superimposed with a torque ripple including a torque ripple having an order unique to the brush motor 100. Feedback control is performed to converge to a target current value IT corresponding to the average value of the motor current. The target current setting unit 12011 sets, for example, the rated current (for example, about 2.0 A) of the motor body 110 as the target current value IT, or in each cycle of the feedback control, for example, a predetermined number of one or two or more immediately before The motor current IM detected by the current detection element 130 is integrated over a fixed period corresponding to the control cycle of the above, and the average value of the motor current IM is set as the target current value IT (Modification Example 1 described later). When the average value of the motor current IM is set as the target current value IT, the target current value IT is updated every control cycle of the feedback control, but is updated only when the brush motor 100 is started. Also, the timing of updating of the target current value IT can be set arbitrarily.

  The subtractor 12012 is an element for subtracting the motor current IM detected by the current detection element 130 from the target current value IT set by the target current setting unit 12011. The subtractor 12012 subtracts the detected motor current IM from the target current value IT, and outputs a difference (IT-IM) between the target current value IT and the motor current IM. If the polarity of the signal indicating the current output from the current detection element 130 is inverted in advance, an adder is used instead of the subtractor 12012. That is, as long as the difference between the target current value IT and the motor current IM can be obtained, any means such as a differential amplifier can be used as the subtractor 12012.

  The current control unit 12013 is an element for performing feedback control based on PI control so that the motor current IM, which is the excitation current of the motor body 110, converges to the target current value IT. In order to perform PWM control of the drive transistor 1204, the current control unit 12013 changes the duty of the PWM signal SP to change the motor current IM flowing through the brush motor 100 to converge it to the target current value IT.

  That is, based on the difference (IT-IM) between target current value IT and motor current IM, current control unit 12013 changes the duty of the PWM signal necessary to change motor current IM toward target current value IT. The duty signal SD indicating the value is output to the PWM signal generator 1202. That is, the current control unit 12013 is a PWM signal so as to reduce the amplitude value of the torque ripple current based on the target current value IT, which is the difference (IT-IM) between the target current value IT and the motor current IM. Control the duty value of Then, the PWM signal generation unit 1202 generates a PWM signal SP having a duty indicated by the duty signal SD, and outputs the PWM signal SP to the gate of the drive transistor 1204 through the drive unit 1203 shown in FIG.

Next, the operation of the brush motor 100 according to the first embodiment of the present invention will be described.
The operation of the brush motor 100 can be roughly divided into the following three processes.
Duty control processing for PWM control of the rotation of the brush motor 100 Overheat prevention processing for preventing overheating due to excessive current of the brush motor 100 Torque ripple reduction for reducing vibration and noise of the brush motor 100 Processing Each of the above-described processing is performed by each component of the duty control unit 1201, the PWM signal generation unit 1202, and the overcurrent detection unit 1205. Each process described above is performed by the microcomputer 1208 that configures the duty control unit 1201, the PWM signal generation unit 1202, and the overcurrent detection unit 1205. For example, the predetermined current value and the predetermined time are defined on a program in which a processing procedure for realizing the function of the duty control unit 1201 is described.

(1) Duty Control Processing FIG. 4 is a flow chart for explaining an operation example of the brush motor 100 according to the first embodiment of the present invention, wherein the duty control unit 1201, the PWM signal generation unit 1202 and the overcurrent detection unit 1205. It is a figure for demonstrating an example of the duty control processing by the microcomputer 1208 which comprises these.
When the user of the vehicle sets the operation switch of the front wiper device to the operation mode from stop to high speed operation or low speed operation, the voltage signal (high speed operation voltage signal or low speed operation voltage signal) corresponding to the operation mode The duty control unit 1201 is input from an external circuit connected to the operation switch.

Then, the duty control unit 1201 determines whether or not the supplied voltage signal is the high-speed operating voltage signal VH (step S1).
At this time, if the supplied voltage signal is the high-speed operating voltage signal VH, the duty control unit 1201 advances the process to step S2. On the other hand, if the supplied voltage signal is not the high-speed operating voltage signal VH, that is, if the supplied voltage signal is the low-speed operating voltage signal VL, the duty control unit 1201 advances the process to step S3.

When the supplied voltage signal is the high-speed operation voltage signal VH, the duty control unit 1201 outputs a control signal with the duty of the pulse of the PWM signal as the duty of the high-speed operation to the PWM signal generation unit 1202.
As a result, the PWM signal generation unit 1202 generates a PWM signal corresponding to a high-speed operation with a preset duty ratio of 100%, for example. Then, the PWM signal generation unit 1202 outputs the generated PWM signal with 100% duty to the drive unit 1203 (step S2).

On the other hand, when the supplied voltage signal is the low-speed operating voltage signal VL, the duty control unit 1201 outputs a control signal having the duty of the pulse of the PWM signal as the duty of the low-speed operation to the PWM signal generation unit 1202. .
As a result, the PWM signal generation unit 1202 generates a PWM signal corresponding to a low-speed operation, which has a preset duty of 60%, for example. Then, the PWM signal generation unit 1202 outputs a PWM signal with a generated duty of 70 percent to the drive unit 1203 (step S3).

The drive transistor 1204 is on / off controlled by the pulse of the PWM signal input via the drive unit 1203. Thus, the drive transistor 1204 supplies and applies a current corresponding to the duty of the pulse in the PWM signal to the motor main body 110 (step S4).
Thus, under the control of the duty control unit 1201, the motor main body 110, which is a brush motor, rotates in one direction at a rotational speed corresponding to high speed operation or low speed operation corresponding to the duty of the pulse of the PWM signal. The wipers of the front or rear wiper device wipe the windshield of the front or rear through the link mechanism.

  As described above, according to the first embodiment, since the control of the operation speed of the brush motor (control of the rotation speed of the brush motor) is performed by PWM control, each brush for high speed and low speed as in the prior art. There is no need to switch between these high and low speed brushes depending on the operating speed. For this reason, it is not necessary to provide the number of the plurality of brushes according to the operation speed. Therefore, according to the first embodiment, for example, the brush for high speed can be omitted, and inconveniences such as an increase in noise, a decrease in life of the commutator, and a decrease in efficiency due to the provision of the brush for high speed are eliminated. can do.

  Further, according to the first embodiment described above, even if the magnetic poles in the brush motor are multi-polarized to four or more, it is necessary to provide a brush for high speed by controlling the operation speed of the brush motor by PWM control. Absent. For this reason, according to the first embodiment, it is possible to avoid the restriction on the assembly accuracy of the brush, and to promote multipolarization and reduction in size and weight. In particular, in the case of the brush motor used for the wiper device, the regulations specify the switching function between low speed operation and high speed operation, the speed difference between low speed and high speed, etc. The case where it can not be satisfied is assumed. However, according to the first embodiment described above, since the rotational speed of the brush motor is adjusted by PWM control, the operating speed of the wiper can be flexibly set in accordance with the regulation by adjusting the duty.

  Further, according to the first embodiment, even if the power supply voltage of the brush motor is increased (for example, increased from 12 V to 42 V, 48 V, etc.), the duty of the PWM signal in PWM control is adjusted. Thereby, the substantial power supply voltage applied to the brush motor can be maintained at a conventional voltage (for example, 12 V). Therefore, according to the first embodiment, any power supply voltage can be flexibly coped with, and even if the power supply voltage is increased, it is continuously used as the brush motor of the conventional front or rear wiper device. It will be possible to Therefore, it is not necessary to take measures to increase the voltage of the motor.

Also, according to the first embodiment, it is possible to realize a brush motor having the desired characteristic requirements required for the front or rear wiper device without requiring a design change on the vehicle side.
Further, according to the first embodiment, when the motor is stopped (the drive motor 1204 is in the off state), the diode 141 and the motor main body 110 form a closed circuit. It can be realized.

  Further, according to the first embodiment, in a situation where the wiper is forcibly moved by an external force, for example, when the external force is an external force corresponding to the rotation direction of the motor, the diode 141 connected to the motor main body 110 A closed circuit effect (electromagnetic brake effect) is obtained, and in the case of an external force corresponding to the motor reverse rotation direction, a closed circuit effect is obtained by the body diode 1204a of the drive transistor 1204.

Further, according to the first embodiment, in the brush motor that generates rotational force in one direction, it is sufficient to include one drive transistor 1204, and the number of drive transistors can be minimized. This can reduce the cost of the apparatus.
Further, according to the first embodiment, it is not necessary to mount a rotation sensor (sensor mug, mall IC or the like) or a relay on the brush motor in a range where general specifications are assumed. Therefore, further cost reduction can be achieved.

(2) Overheat Prevention Process Each of FIGS. 5 to 7 is a diagram for explaining the overheat prevention process in the operation example of the brush motor 100 according to the first embodiment of the present invention. Here, FIG. 5 is an overall flowchart of the overheat prevention process, FIG. 6 is a detailed flowchart of the heat protection process in the overheat prevention process of FIG. 5, and FIG. 7 is a detailed flowchart of the recovery process in the heat prevention process of FIG. is there.
The overheat prevention process is performed in parallel with the duty control process (steps S21 to S23) of the flowchart of FIG. 4 described above.

  FIG. 8 is a diagram showing a configuration example of a set current value table showing the relationship between the set current value for each overheat protection processing stored in the storage unit in the duty control unit 1201 and the set time corresponding to the set current value. It is. In FIG. 8, the set current values are each of a plurality of different limit load currents (currents leading to overheating with time) of the overheat protection n processing and a restraint current (current at overload where rotation of the brush motor can not be performed, ie maximum current). The current value of The return setting time is the time from when the brush motor 100 is stopped to when the brush motor 100 is reactivated. That is, the return setting time is the time required to reduce the temperature of zero. The fail flag is provided for each overheat protection process, and is a flag that is set when the current whose current value exceeds the set current value flows over the set time corresponding to the set current value and is stopped. If the fail flag field is 1, it is assumed that the flag is set, and if the flag field is 0, the flag is not set. Further, the set current value may be set to indicate the range of the current value.

For example, assuming that the set current value is VT, the limit load current is 10 (A) ≦ VT <12 (A) for the overheat protection 1 process described later, and 12 (A) ≦ VT <14 for the overheat protection 2 process. A): 14 (A) ≦ VT <16 (A) for the overheat protection 3 processing, and the constraint current for the overheat protection 4 processing is pre-written in the set current value table as 16 (A) <VT It is done. Further, the setting times of the overheat protection 1 process, the overheat protection 2 process, the overheat protection 3 process, and the overheat protection 4 process are set to 20 (seconds), 10 (seconds), 5 (seconds), and 2 (seconds). The recovery setting time of each of the overheat protection 1 process, the overheat protection 2 process, the overheat protection 3 process, and the overheat protection 4 process is set to 10 (seconds), 10 (seconds), 20 (seconds) and 20 (seconds).
Hereinafter, the overheat prevention processing in the present embodiment will be described using each of FIGS. 4 to 7.

  When the user of the vehicle operates the operation switch of the wiper device to operate the wiper device, the overcurrent detection unit 1205 monitors the current value detected by the current detection element 130. Further, the duty control unit 1201 executes the process of the flowchart of FIG. 5 each time a control cycle interrupt for activating the overheat prevention process occurs.

  The duty control unit 1201 refers to the column of the fail flag of each set current value in the set current value table, and confirms the presence or absence of the column of the fail flag (the flag is set to 1) (step S11). At this time, if there is no set current value for which the fail flag is set, the duty control unit 1201 advances the process to step S12. In this case, the brush motor is operating. On the other hand, if there is a set current value for which the fail flag is set, the duty control unit 1201 advances the process to step S13. In this case, the brush motor is not operating (stopped).

  When the fail flag is not set, the duty control unit 1201 causes the PWM signal generation unit 1202 in the flowchart of FIG. 3 to generate a duty PWM signal (duty output). Then, the duty control unit 1201 performs on / off control of the drive transistor (FET) 1204, operates the brush motor 100, and advances the process to step S14 (step S12).

  On the other hand, when the fail flag is set, the duty control unit 1201 performs return processing for reactivating the brush motor (step S13). At this time, when the condition for return (described later) is satisfied, the duty control unit 1201 restarts the brush motor by the operation according to the flowchart of FIG. 3. Further, if the condition for recovery is not satisfied, the duty control unit 1201 ends the processing of the cycle in the control cycle interrupt.

When the brush motor 100 is in operation, the duty control unit 1201 performs overheat protection 1 processing (step S14), overheat protection 2 processing (step S15), overheat protection 3 processing (step S16), and overheat protection 4 processing (step S17). Perform the processing of When the overheat protection 4 process ends, the duty control unit 1201 ends the process of the cycle in the control cycle interrupt.
Here, for example, in each of the overheat protection 1 process, the overheat protection 2 process, and the overheat protection 3 process, the limit load current value as the set current value corresponding to the current value of the current flowing to the motor main body 110 corresponds to each process. It is a process to prevent overheating caused by over current when it is exceeded. The fourth overheat protection process is a process for preventing overheat due to an overcurrent when the current value of the current flowing through the motor main body 110 exceeds the restricted current value as the set current value. The current value indicated by the set current value gradually increases in the order of the overheat protection 1 process, the overheat protection 2 process, the overheat protection 3 process, and the overheat protection 4 process. The limit load current value may be set to four or more if necessary, and the corresponding overheat protection n processing is provided.

  Next, the overheat protection n processing will be described with reference to FIG. In the present embodiment, the overheat protection n processing corresponds to each of the overheat protection 1 processing, the overheat protection 2 processing, the overheat protection 3 processing, and the overheat protection 4 processing, and n is 1 ≦ n ≦ 4. That is, although each of the overheat protection 1 process, the overheat protection 2 process, the overheat protection 3 process, and the overheat protection 4 process is different in the set current value and the set time, the process itself is the same. Each of the set current values in the set current value table of FIG. 7 is a set current value used in each of the overheat protection 1 process, the overheat protection 2 process, the overheat protection 3 process, and the overheat protection 4 process.

  The overcurrent detection unit 1205 reads the set time n corresponding to the overheat protection n processing from the set current value table of the duty control unit 1201. Then, the overcurrent detection unit 1205 determines whether the current value of the motor current, which is the current measured by the current detection element 130, exceeds the set current value n read from the set current value table (step S21). . At this time, if the current value of the current measured by the current detection element 130 exceeds the preset current value, the overcurrent detection unit 1205 sets the current value of the current measured by the current detection element 130 in advance. A notification indicating that the set current value is exceeded is notified to the duty control unit 1201. Then, the overcurrent detection unit 1205 advances the process to step S22. On the other hand, when the current value of the current measured by the current detection element 130 does not exceed the preset current value, the overcurrent detection unit 1205 sets the current value of the current measured by the current detection element 130 in advance. A notification indicating that the set current value is not exceeded is notified to the duty control unit 1201. Then, the overcurrent detection unit 1205 advances the process to step S23.

When the current value of the current measured by the current detection element 130 exceeds the preset current value, the duty control unit 1201 starts counting up (counting the elapsed time) of the energization time measurement counter 1201a_n (step S22). Then, duty control unit 1201 advances the process to step S24.
The energization time measurement counter 1201a_n is a conduction time measurement counter 1201a for counting time provided in the duty control unit 1201 for each overheat protection n process, and is a counter corresponding to the overheat protection n process.

  When the current value of the current measured by the current detection element 130 does not exceed the preset current value, the duty control unit 1201 stops the count-up of the conduction time measurement counter 1201a_n, and sets the elapsed time measured to 0. The counter value to be cleared is cleared (step S23). Then, the duty control unit 1201 returns the process to the process of the flowchart of FIG. 5.

  The duty control unit 1201 reads out the set time n corresponding to the overheat protection n processing from the set current value table. Then, the duty control unit 1201 determines whether or not the counter n value (time) counted by the energization time measurement counter 1201a_n exceeds the set time n read from the set current value table (step S24). At this time, the duty control unit 1201 advances the process to step S25 when the counter n value counted by the energization time measurement counter 1201a_n exceeds the set time n. On the other hand, the duty control unit 1201 returns the process to the process of the flowchart of FIG. 5 when the counter n value counted by the energization time measurement counter 1201a_n does not exceed the set time n.

  The duty control unit 1201 outputs a control signal that sets the duty of the pulse of the PWM signal to 0 to the PWM signal generation unit 1202 when the counter n value counted by the conduction time measurement counter 1201a_n exceeds the setting time n. (Step S25). Thus, the PWM signal generation unit 1202 sets the duty (DUTY) of the pulse of the PWM signal to zero. That is, the PWM signal generation unit 1202 stops the output of the PWM signal. Therefore, when the drive transistor 1204 (FET) is always in the OFF state, the motor current flowing to the brush motor 100 becomes zero, and the brush motor 100 stops its operation. Then, the duty control unit 1201 advances the process to step S26.

  The duty control unit 1201 sets a fail flag corresponding to the overheat protection n process in the set current value table (step S26). Then, the duty control unit 1201 returns the process to the process of the flowchart of FIG. 5.

  In addition, the set time will be additionally described. In each of the above-described overheat protection n processes, the duty control unit 1201 controls the drive transistor 1204 to be turned off after an overcurrent is detected according to a preset current range of the preset current value of the limit load current set in advance. Set up the above set time. That is, the predetermined time is set for each overheat protection n process according to the magnitude of the overcurrent.

  For example, as the setting current range of the setting current value of the limit load current, the setting current range of 10 to 12 A (amps) in the overheat protection 1 process, the setting current range of 12 to 14 A in the overheat protection 2 process, and 14 in the overheat protection 3 process The set current range of -20 A and the set current range of 20 A or more in the overheat protection 4 processing are set in advance. When the current detected by the current detection element 130 is within the set current range in the overheat protection 1 process, the duty control unit 1201 controls the drive transistor 1204 to be turned off after the overcurrent detection unit 1205 detects an overcurrent. The above predetermined time up to is set to, for example, 20 seconds. In this case, the drive transistor 1204 is controlled to be turned off 20 seconds after the occurrence of the overcurrent, and the overcurrent is cut off.

  In addition, when the overcurrent detected by the current detection element 130 is within the set current range in the overheat protection 2 processing, the duty control unit 1201 controls the drive transistor 1204 to be in the OFF state after the overcurrent is detected (PWM signal The above-mentioned predetermined time until duty of 0 is 0 is set to 10 seconds, for example. In this case, the drive transistor 1204 is controlled to be turned off 10 seconds after the occurrence of the overcurrent. As described above, the larger the current value of the overcurrent detected by the overcurrent detection unit 1205, the shorter the time from the generation of the overcurrent to the generation of the overheat. Therefore, the drive transistor 1204 is controlled to be in the OFF state. The above predetermined time until is set to a short time. Thus, the duty control unit 1201 can cut off the overcurrent to the motor main body 110 before the brush motor 100 is overheated.

Next, the return processing will be described with reference to FIG. A return time counter in the following description is provided in the duty control unit 1201 for each overheat protection n process.
The duty control unit 1201 reads, from the set current value table, the return setting time corresponding to the overheat protection n processing in which the fail flag is set.
The duty control unit 1201 determines whether or not the time counted by the recovery time counter exceeds the recovery set time read from the set current value table (step S31). At this time, if the time counted by the return time counter exceeds the return setting time, the duty control unit 1201 advances the process to step S32. On the other hand, if the time counted by the return time counter does not exceed the return setting time, the duty control unit 1201 advances the process to step S33.

  If the time (count value) counted by the recovery time counter exceeds the recovery setting time, the duty control unit 1201 sets the counter value of the recovery time counter to 0 and performs processing to clear the recovery time counter (step S32). . Then, the duty control unit 1201 advances the process to step S33.

  If the time counted by the recovery time counter does not exceed the recovery setting time, the duty control unit 1201 counts up the count value of the recovery time counter (step S33). Then, the duty control unit 1201 returns the process to the process of the flowchart of FIG. 5.

  The duty control unit 1201 clears all the fail flags in the set current value table (sets the fail flag column to 0) (step S34). Then, the duty control unit 1201 advances the process to step S33.

  The duty control unit 1201 outputs a control signal having a duty of a pulse of the PWM signal corresponding to the flowchart of FIG. 3 to the PWM signal generation unit 1202 (step S35). Thereby, the PWM signal generation unit 1202 generates a PWM signal as a duty (DUTY) of the pulse of the PWM signal as a duty corresponding to the high speed operation or the low speed operation. That is, the PWM signal generation unit 1202 outputs a PWM signal of a duty corresponding to high speed operation or low speed operation to the drive unit 1203. Therefore, the drive transistor 1204 (FET) is on / off controlled by the PWM signal, whereby a motor current corresponding to high speed operation or low speed operation flows to the brush motor 100, and the brush motor 100 restarts operation. Then, the duty control unit 1201 returns the process to the process of the flowchart of FIG. 5.

Next, regarding the operation example of the brush motor 100, the torque ripple reduction processing by the duty control unit 1201 shown in FIG. 3 described above will be specifically described along the flow shown in FIG. FIG. 9 is a flowchart showing an operation example of the torque ripple reduction process in the operation example of the brush motor 100 according to the first embodiment of the present invention.
FIG. 10 is a waveform diagram for explaining the torque ripple reduction process in the operation example of the brush motor 100 according to the first embodiment of the present invention. FIG. 10A shows a waveform of the motor current IM detected by the current detection element 130. FIG. FIG. 10B is a diagram for describing the relationship between duty control and motor current IM in the torque ripple reduction process.
FIG. 11 is a detailed waveform diagram for explaining the details of the torque ripple reduction process in the operation example of the brush motor 100 according to the first embodiment of the present invention, and illustrates the relationship between the motor current IM and the duty of the PWM signal SP. FIG.
The torque ripple reduction process is performed in parallel with the duty control process according to the flowchart of FIG. 4 described above and the overheat prevention process according to the flowcharts of FIGS. 5 to 7.

  When the operation switch of the wiper device is operated, and low speed operating voltage signal VL or high speed operating voltage signal VH corresponding to the operating speed is supplied to brush motor 100, either of these signals serves as a power supply for low speed operating voltage signal VL. The power is supplied to the motor main body 110 through the above-described wiring, the diode 143 (FIG. 2), and the power is turned on.

When the power is turned on, the duty control unit 1201 shown in FIG. 6 passes a period (start current generation period) in which a start current is generated when the motor main body 110 starts, and continues until the start current generation period elapses. The process waits without performing the duty control process (step S51).
When the start current generation period has elapsed, the target current setting unit 12011 of the duty control unit 1201 sets a target current value IT (step S52). For example, the target current setting unit 12011 sets a rated current (for example, about 2.0 A) of the motor body 110 when the wiper device operates at low speed or high speed as the target current value IT.

Next, the duty control unit 1201 reads the motor current IM detected by the current detection element 130 (step S53).
Then, the subtractor 12012 subtracts the motor current IM read by the current detection element 130 from the target current value IT set by the target current setting unit 12011, and the difference between the target current value IT and the motor current IM (IT− IM) is calculated and output to the current control unit 12013.

  The current control unit 12013 performs feedback control based on PI control for causing the motor current IM to converge on the target current value IT based on the difference (IT-IM) input from the subtractor 12012. The current control unit 12013 calculates the duty of the PWM signal for causing the motor current IM to converge to the target current value IT in the process of PI control (step S54), and the duty signal indicating the duty obtained as the calculation result Output SD. That is, current control unit 12013 reduces the amplitude value of the torque ripple current based on target current value IT, which is the difference between target current value IT and motor current IM (IT-IM). A value is generated and output as a duty signal SD. In this case, as exemplified in FIG. 10B and FIG. 11, current control unit 12013 currently sets the duty of PWM signal SP in a period Ta in which motor current IM (solid line) exceeds target current value IT (dotted line). In the period Tb in which the motor current IM falls below the target current value IT, the duty of the PWM signal SP is increased more than the current duty.

  The PWM signal generation unit 1202 generates a PWM signal SP having a duty indicated by the duty signal SD input from the duty control unit 1201 (current control unit 12013), and drives the driving transistor 1204 by the PWM signal SP through the driving unit 1203. (Step S55). The drive transistor 1204 is turned on / off in accordance with the duty of the PWM signal SP, supplies the motor current IM to the motor body 110 in the on period, and cuts off the motor current IM in the off period.

  As described above, the motor current IM (averaged current) of the motor main body 110 flowing through the drive transistor 1204 is adjusted toward the target current value IT, and converges and stabilizes near the target current value IT. It is feedback controlled. As a result, the waveform of the motor current IM becomes substantially linear. When the waveform of the motor current IM becomes linear, the waveform of the torque ripple contained in the rotational torque generated by the motor main body 110 also becomes linear, and the torque ripple is reduced. As a result, the vibration and noise of the brush motor 100 due to the torque ripple are reduced.

Next, a modified example of the above-described torque ripple reduction process in the present embodiment will be described.
First Modified Example FIG. 12 is a view for explaining a first modified example of the torque ripple reduction process in the operation example of the brush motor 100 according to the first embodiment of the present invention, and is a first modified example of the torque ripple process. FIG. 14 is a block diagram showing an example of the configuration of a duty control unit 1201A that implements the above.
In the first modification, the brush motor 100 includes a duty control unit 1201A shown in FIG. 12 instead of the duty control unit 1201 shown in FIG. 3 as a duty control unit that implements the modification of the torque ripple processing. Also in FIG. 12, only the elements related to the first modification of the torque ripple reduction process are shown, and the elements related to the duty control process and the overheat prevention process described above are omitted.

  The duty control unit 1201A according to the first modification of FIG. 12 further includes a duty limit processing unit 12014 in addition to the configuration of the duty control unit 1201 shown in FIG. Further, in the first modification, the target current setting unit 12011 sets, as the target current value IT, an average current value IMave which is an average value of the currents detected by the current detection element 130 over a predetermined period. The duty limit processing unit 12014 controls the motor current flowing through the brush motor 100 within a predetermined range (a range from the lower limit current value IML to the upper limit current value IMH in FIG. 14B described later) based on the average current value IMave. Restrict. Others are the same as the duty control unit 1201 shown in FIG.

Next, regarding the operation example of the brush motor 100, a first modified example of the torque ripple reduction processing by the duty control unit 1201A shown in FIG. 12 described above will be specifically described along the flow shown in FIG.
The torque ripple reduction process of the first modification is also performed in parallel with the duty control process according to the flowchart of FIG. 4 and the overheat prevention process according to the flowcharts of FIGS. 5 to 7 described above.

FIG. 13 is a flowchart of a first modified example of the torque ripple reduction process in the operation example of the brush motor 100 according to the first embodiment of the present invention.
FIG. 14 is a waveform diagram for explaining a first modification of the torque ripple reduction process in the operation example of the brush motor 100 according to the first embodiment of the present invention. Here, FIG. 14A shows the waveform of the motor current detected by the current detection element 130, and FIG. 14B shows the relationship between the duty control and the motor current in the torque ripple reduction process according to the first modification. It is a figure for demonstrating.

  When the operation switch of the wiper device is operated and the power is turned on, the duty control unit 1201A shown in FIG. 12 passes the start current generation period and does not execute the duty control process until the start current generation period elapses. It waits (step S61). When the start current generation period has elapsed, the target current setting unit 12011 of the duty control unit 1201A integrates the motor current IM detected by the current detection element 130 over a predetermined fixed period, and based on the integrated current, An average current value IMave (broken line) is calculated (step S62). Then, the target current setting unit 12011 sets the average current value IMave of the motor current IM as the target current value IT (step S63).

  Here, the technical significance of setting the average current value IMave of the motor current IM as the target current value IT will be supplemented. The motor current IM detected by the current detection element 130 includes a ripple current component of an order unique to the brush motor 100 as exemplified by a solid line in FIG. Brings torque ripple. By averaging the torque ripples, torque ripples can be reduced, and vibration and noise of the brush motor 100 due to the torque ripples can be suppressed. Therefore, the target current setting unit 12011 calculates an average current value IMave (broken line) of the motor current IM corresponding to the motor torque when averaging the torque ripple, and sets this as the target current value IT. Thus, only torque ripple can be reduced without affecting the rotational speed of the brush motor 100.

  Subsequently, the duty control unit 1201 reads the motor current IM detected by the current detection element 130 (step S64). The subtractor 12012 subtracts the motor current IM read from the current detection element 130 from the target current value IT set by the target current setting unit 12011, and the difference between the target current value IT and the motor current IM (IT-IM) Are calculated and output to the current control unit 12013.

  The current control unit 12013 implements feedback control by PI control for causing the motor current IM to converge to the target current value IT (average current value IMave) based on the difference (IT-IM) input from the subtractor 12012. Do. The current control unit 12013 calculates the duty of the PWM signal necessary for causing the motor current IM to converge to the target current value IT in the process of the PI control (step S65), and outputs the duty signal SD indicating the duty. . That is, current control unit 12013 reduces the amplitude value of the torque ripple current based on target current value IT, which is the difference between target current value IT and motor current IM (IT-IM). A value is generated and output as a duty signal SD.

  Here, basically, current control unit 12013 performs a period Ta in which motor current IM indicated by a solid line in FIG. 14B exceeds target current value IT, as in the case shown in FIG. 10B described above. The duty of the PWM signal SP is decreased below the current duty, and conversely, the duty of the PWM signal SP is increased over the current duty in a period Tb in which the motor current IM falls below the target current value IT.

  Then, the duty limit processing unit 12014 carries out duty limit processing for limiting the duty of the PWM signal calculated in step S65 (step S66). That is, duty limit processing unit 12014 limits motor current IM flowing through brush motor 100 within a predetermined range based on target current value IT provided by average current value IMave.

  Specifically, the duty limit processing unit 12014 performs a PWM control using the duty of the PWM signal calculated in step S65 as it is, and the motor current IM assumed (determined) is a predetermined lower limit current. If it is within the range between the value IML and the upper limit current value IMH, the duty signal SD indicating the duty is output without restricting the duty of the PWM signal calculated in step S65 described above.

  On the other hand, if the motor current IM assumed (obtained) is lower than a predetermined lower limit current value IML, the duty limit is assumed when PWM control is performed using the duty of the PWM signal calculated in step S65 described above as it is. Processing unit 12014 limits the duty of PWM signal SP to a value corresponding to lower limit current value IML. As a result, an excessive decrease in motor current IM is suppressed in the process of feedback control in period Ta shown in FIG. 14B, and a rapid decrease in rotational speed of brush motor 100 is suppressed.

  Conversely, when the motor current IM assumed (obtained) is higher than a predetermined upper limit current value IMH assumed when PWM control is performed using the duty of the PWM signal calculated in step S65 described above as it is, duty limit processing is performed. Unit 12014 limits the duty of PWM signal SP to a predetermined duty corresponding to upper limit current value IMH. As a result, an excessive increase in motor current IM is suppressed in the process of feedback control in period Tb shown in FIG. 14B, and a rapid increase in rotational speed of brush motor 100 is suppressed.

  Here, the lower limit current value IML and the upper limit current value IMH will be supplemented. If the difference between the lower limit current value IML and the upper limit current value IMH and the average current value IMave can be made smaller, the fluctuation amount of the rotational speed of the brush motor 100 in feedback control can be made smaller. It takes time to converge to the value IMave. Conversely, if the difference between each of the lower limit current value IML and the upper limit current value IMH and the average current value IMave is increased, the fluctuation amount of the rotational speed of the brush motor 100 in feedback control becomes large. The time until convergence to the value IMave can be shortened. Based on such characteristics, the lower limit current value IML and the upper limit current value IMH can be arbitrarily set in accordance with the allowable amount of fluctuation of the rotational speed of the brush motor 100.

  Subsequently, after the above-described duty limit process (step S66), PWM control based on the duty indicated by the duty signal SD is performed (step S67). That is, PWM signal generation unit 1202 generates PWM signal SP having a duty indicated by duty signal SD input from duty limit processing unit 12014 of duty control unit 1201 A, and drive transistor 1204 receives PWM signal SP through drive unit 1203. Drive. The drive transistor 1204 is turned on / off in accordance with the duty of the PWM signal SP, supplies the motor current IM to the motor body 110 in the on period, and cuts off the motor current IM in the off period.

  As a result of the drive transistor 1204 being turned on / off based on the PWM signal SP, the motor current IM of the motor main body 110 flowing through the drive transistor 1204 is adjusted toward the target current value IT (average current value IMave) Feedback control is performed so as to converge and stabilize in the vicinity of the value IT. When the motor current IM of the motor body 110 stabilizes near the target current value IT, the torque ripple included in the rotational torque generated by the motor body 110 is reduced. As a result, the vibration and noise of the brush motor 100 due to the torque ripple are reduced.

  According to the first modification described above, duty limit processing unit 12014 limits motor current IM within a certain range defined by lower limit current value IML and upper limit current value IMH set based on average current value IMave. Therefore, in the process of feedback control of the motor current IM in order to average the torque ripple, the change in rotation of the motor current IM of the brush motor 100 is suppressed. Therefore, according to the first modification, it is possible to reduce vibration and noise while suppressing rapid fluctuations in the rotational speed of the brush motor 100.

  As a reference example, the response characteristic of PWM control in the case where the duty at the time of start is 0.7 and the fluctuation range of the duty of the PWM signal SP is ± 0.05 will be described. When the above-described duty limit process (step S66) is not performed, when the load of the brush motor 100 (for example, the wiping resistance of the wiper device) rises and the motor current IM rises, the motor current IM is averaged by the average current value IMave by feedback control. The duty of the PWM signal SP is reduced in the process of convergence to. The reduction amount of the duty at this time becomes larger as the load is larger. As a result, when the motor current IM is excessively reduced, the voltage applied between the brush 111A and the brush 111B of the motor body 110 is rapidly reduced, and the rotational speed of the brush motor 100 is significantly reduced. Therefore, the operation of the wiper device may be temporarily unstable.

  On the other hand, the motor current IM deviates from the fixed range defined by the lower limit current value IML and the upper limit current value IMH in the process of the above-described feedback control by providing the above-described duty limit process (step S66). There is no For this reason, the rotational speed of the brush motor 100 does not fluctuate rapidly and is stabilized.

Second Modified Example In the torque ripple reduction process of the first modified example described above, the motor current IM is feedback-controlled so that the waveform of the motor current IM becomes linear. On the other hand, in the second modification, the motor current IM is reduced so that the number of ripples of the motor current IM corresponding to the torque ripple of the brush motor 100 is reduced, that is, the number of ripples of the motor current IM is smaller. Feedback control. The other configuration and operation are similar to those of the first modification described above.

  That is, as exemplified in FIG. 10 (B) and FIG. 11, current control unit 12013 sets the duty of PWM signal SP to a current value in period Ta in which motor current IM (solid line) exceeds target current value IT (dotted line). The duty is decreased from the duty, and conversely, the duty of the PWM signal SP is increased from the present duty in a period Tb in which the motor current IM falls below the target current value IT. Then, the current control unit 12013 adjusts the duty of the PWM signal SP so that the number of ripples of the motor current IM is smaller than the number of ripples of the torque ripple generated in the state without control. Feedback control of the motor current IM.

  According to the second modification, the torque ripple of the brush motor 100 changes in conjunction with the waveform of the motor current IM, and as a result, the order of the torque ripple changes according to the number of ripples of the motor current IM. Therefore, by appropriately reducing the number of ripples of the motor current IM, it is possible to change the vibration mode of the brush motor 100 and improve the tone of noise. For example, among the frequency components included in the noise of the brush motor 100, it is possible to reduce high frequency noise that may cause discomfort in human hearing.

  Although the above-described torque ripple reduction processing is performed in parallel with the above-described duty control processing, in this case, the increase and decrease of the duty is controlled based on the duty of the PWM signal set by the duty control processing. Ru. Thus, while the control of the rotational speed of the brush motor is performed in the duty control process, the control for reducing the torque ripple is performed in the torque ripple reduction process. That is, the duty control process and the torque ripple reduction process are performed in parallel.

  In the above-described embodiment, the duty control unit 1201 (1201A) performs three different types of processing including duty control processing, overheat prevention processing, and torque ripple reduction processing. However, the overheat prevention processing is performed. Instead, two processes of the duty control process and the torque ripple reduction process may be performed.

FIG. 15 is a diagram showing another example in which each of the duty control unit 1201 and the PWM signal generation unit 1202 in the control substrate 120 is configured using a microcomputer.
The configuration of FIG. 15 has the same function as that of the circuit shown in FIG. 2, and the same reference numerals are given to the same components. The configuration of FIG. 15 does not have a snow clutch. Further, the sensing of the output shaft of the motor main body 110 is performed by a microcomputer. In the relay plate 150A, the start contact S is a contact that generates timing for operating the front or rear wiper device.

FIG. 16 is a diagram showing another example in which each of the duty control unit 1201 and the PWM signal generation unit 1202 in the control substrate 120 is configured using a microcomputer.
The configuration of FIG. 16 has the same function as that of the circuit shown in FIG. 2, and the same reference numerals are given to the same components. In the configuration of FIG. 16, a snow clutch is provided. Further, the sensing of the output shaft of the motor main body 110 is performed by a microcomputer. In the relay plate 150B, the start contact S is a contact that generates timing for operating the front or rear wiper device.

  Each of the brush motor 100 of FIG. 2, the brush motor 100A of FIG. 15, and the brush motor 100B of FIG. 16 is different in whether the motor rotational shaft of the motor body 110 is sensed by a microcomputer or not However, the configuration of the present embodiment can be used for any of the conventional configurations without changing these conventional configurations.

Next, the arrangement of the control board 120 will be described in detail with reference to FIG.
FIG. 17 is a view showing an arrangement example of the control board 120 provided in the brush motor 100 according to the first embodiment of the present invention. Wiring and the like in detail are omitted.

  Here, FIG. 17A shows a first arrangement example (mechanical angle 90 °) of the brushes 111A and 111B when the number of magnetic poles of the brush motor 100A is four. The brush 111A and the brush 111B are arranged at mutually different positions by 90 ° in mechanical angle on an annular brush holder 110H incorporated in the housing portion MH of the motor portion M.

In the first arrangement example of FIG. 17A, there is an area on the brush holder 110H where a brush is not disposed at a position facing each of the brush 111A and the brush 111B with the rotating armature (not shown) interposed therebetween. . That is, in the example of FIG. 17A, as described above, since the brush for high speed operation for high speed operation is not required by the PWM control, approximately 0 ° to 270 in the clockwise direction based on the brush 111B. There is no brush in the area of °. A control substrate 120 (duty control unit 1201, PWM signal generation unit 1202, drive unit 1203) and a current detection element 130 are disposed in an area on the brush holder 110H where the brush does not exist. When each of the duty control unit 1201 and the PWM signal generation unit 1202 is not a discrete circuit but a microcomputer, a microcomputer chip and a drive unit 1203 are disposed on the control substrate.
Here, as described above, since there is no brush in the region where the control substrate 120 and the current detection element 130 are disposed, the control substrate 120 and the current detection element 130 do not interfere with the brush, and the motor It is accommodated in the inside of the housing part MH of the part M.

  FIG. 17B shows a second arrangement example (mechanical angle 180 °) of the brushes 111A and 111C when the number of magnetic poles of the brush motor 100 is six. The brush 111A and the brush 111C are arranged at different mechanical angles by 180 ° on an annular brush holder 110H which forms a part of the housing portion MH of the motor portion M.

Here, in the example of FIG. 17 (B), there are areas where the brushes are not arranged at positions different by 60 ° and 120 ° in mechanical angle with respect to each of the brushes 111A and 111C on the brush holder 110H. Do. That is, in the example of FIG. 17B, as described above, since the brush for high speed operation for high speed operation is not required by the PWM control, approximately 0 ° to 180 in the clockwise direction based on the brush 111A. There are no brushes in the first region of ° and the second region of approximately 0 ° to 180 ° in the counterclockwise direction with respect to the brush 111A. The current detection element 130 is disposed in the first area, and the control substrate 120 is disposed in the second area. When each of the duty control unit 1201 and the PWM signal generation unit 1202 is not a discrete circuit but a microcomputer, a microcomputer chip and a drive unit 1203 are disposed on the control substrate.
Here, as in FIG. 17A, since there is no brush in the region where the control substrate 120 and the current detection element 130 are disposed, the control substrate 120 and the current detection element 130 interfere with the brush. Instead, it is housed inside the housing part MH of the motor part M.

  FIG. 17C shows a third arrangement example (mechanical angle: 180 ° each) of the brushes 111A, 111D, 111E, 111F when the number of magnetic poles of the brush motor 100 is six. In the mechanical angle, the brushes 111A and 111E different from each other by 180 ° correspond to positive and negative, respectively, and similarly, the mechanical angles different from each other by 180 ° from the brushes 111D and 111F are another positive pair, It corresponds to the negative electrode. The brushes 111A and 111D are disposed at positions different by 60 ° in mechanical angle, and the brushes 111E and 111F are also disposed at positions different by 60 ° in mechanical angle.

In the example of FIG. 17C, the third region of approximately 0 ° to 120 ° in the clockwise direction with respect to the brush 111D and the substantially 0 ° to 120 ° in the counterclockwise direction with respect to the brush 111A. There is no brush in the fourth area of. The current detection element 130 is disposed in the third area, and the control substrate 120 is disposed in the fourth area. That is, in the example of FIG. 17C, as described above, since the brush for high speed operation is not required by the PWM control, as described above, it is approximately 0 ° in the clockwise direction based on the brush 111A. There are no brushes in the third region of ̃120 ° and the fourth region of approximately 0 ° ̃120 ° in the counterclockwise direction with respect to the brush 111A. The current detection element 130 is disposed in the third region, and the control substrate 120 is disposed in the fourth region. When each of the duty control unit 1201 and the PWM signal generation unit 1202 is not a discrete circuit but a microcomputer, a microcomputer chip and a drive unit 1203 are disposed on the control substrate.
Here, as in FIG. 17A, since there is no brush in the region where the control substrate 120 and the current detection element 130 are disposed, the control substrate 120 and the current detection element 130 interfere with the brush. Instead, it is housed inside the housing part MH of the motor part M.

FIG. 17D shows a fourth arrangement example (a mechanical angle of 60 °) of the brushes 111A and 111D when the number of magnetic poles of the brush motor 100 is six. The brushes 111A and 111D, which differ from each other by 60 ° in mechanical angle, correspond to two poles. Further, in the example of FIG. 17D, as described above, since the brush for high speed operation is not required by the PWM control, approximately 0 ° to 300 ° in the clockwise direction with reference to the brush 111D. There are no brushes in the 5 area. The current detection element 130 and the control substrate 120 are disposed in the fifth region. When each of the duty control unit 1201 and the PWM signal generation unit 1202 is not a discrete circuit but a microcomputer, a microcomputer chip and a drive unit 1203 are disposed on the control substrate.
Here, as in FIG. 17A, since there is no brush in the region where the control substrate 120 and the current detection element 130 are disposed, the control substrate 120 and the current detection element 130 interfere with the brush. Instead, it is housed inside the housing part MH of the motor part M.

  As described above, according to the present embodiment, the motor current IM flowing to the motor main body 110 is measured, and the duty of the PWM signal is adjusted so that the torque ripple superimposed on the measured motor current IM is reduced. . As a result, according to the present embodiment, the torque ripple is reduced by controlling the duty of the PWM signal, so that the vibration and noise of the brush motor 100 due to the torque ripple are reduced.

  Further, according to the first embodiment, the overcurrent that has caused the overheating can be suppressed for each of the plurality of set current values by the above-described overcurrent prevention process. Therefore, it is possible to prevent overheating of the motor main body 110 corresponding to the current value of the overcurrent without using the thermal protection element. As a result, in general, a current detection element that is smaller and less expensive than a thermal protection element can be used, and therefore, according to the present embodiment, the device can be protected from overheating in the same manner as the thermal protection element. In addition to the above, the device can be miniaturized and the manufacturing cost can be reduced.

Further, according to the first embodiment, the duty control unit 1201 and the overcurrent detection unit 1205 are realized by the microcomputer 1208, and each function is defined by the program of the microcomputer 1208. Even if the specification of the motor main body 110 is changed without changing the circuit configuration by setting the predetermined time again, it is possible to easily take measures against overheat according to the specification.
According to the first embodiment described above, by performing the overcurrent prevention process based on the detection signal of the current detection element 130, the motor main body 110 can be obtained without using a thermal protection element such as a circuit breaker or a PTC element. It is possible to prevent overheating due to flowing overcurrent. Therefore, the device subjected to the overheat prevention measure can be realized inexpensively and in a small size.

Further, according to the first embodiment, since it is not necessary to provide the thermal protection element for the overheat prevention measure, the complicated operation for attaching the thermal protection element to the brush motor 100 becomes unnecessary, and the number of tuning steps of the thermal protection element Can be reduced.
Further, according to the first embodiment, since it is not necessary to consider the variation in the characteristics of the thermal protection element for the prevention of overheat, an excessive design with a margin for absorbing the variation in the characteristics of the thermal protection element is provided. There is no need to do it.

  Further, according to the first embodiment, when the brush motor 100 is used as a power source of the front wiper device and the rear wiper device, the control substrate 120 is composed of the brush motor on the front wiper device side and the brush motor on the rear wiper device side. By sharing, the cost of the whole wiper device can be reduced.

  Further, according to the first embodiment described above, the number of brushes is reduced by using the pressure equalizing line for the rotary armature of the motor main body 110, and the heat protection is provided to the vacant area on the brush holder 110H generated thereby. Since the element 123 and the control board 120 are arranged, the control board 120 and the like can be accommodated inside the housing part MH of the motor part M without increasing the size of the brush motor 100. Therefore, according to the first embodiment, the device can be miniaturized while achieving multipolarization. Further, since the rotational speed of the motor main body 110 is controlled by the PWM control, the rotational speed can be changed without switching the brush.

Further, according to the first embodiment, in the brush motor that generates rotational force in one direction, it is sufficient to include one drive transistor 1204, and the number of drive transistors can be minimized. This can reduce the cost of the apparatus.
Further, according to the first embodiment, it is not necessary to mount a rotation sensor (sensor magnet, Hall IC or the like) or a relay on the brush motor in a range where general specifications are assumed. Therefore, further cost reduction can be achieved.

  Further, according to the first embodiment, since the speed control of the brush motor is performed by the PWM control, it is not necessary to provide the number of the plurality of brushes according to the speed. For this reason, for example, disadvantages such as an increase in noise, a decrease in life of the commutator, and a decrease in efficiency due to the provision of the high-speed brush can be resolved.

  In addition, even if the number of poles is increased to four or more, the restriction on the assembling accuracy of the brush can be avoided, and the number of poles and the reduction in size and weight can be promoted. In particular, in the case of a wiper motor, the law stipulates the switching function between low speed operation and high speed operation, the speed difference between low speed and high speed, etc. Although a case is assumed, according to the first embodiment described above, since the rotation speed of the motor is adjusted by PWM control, the operation speed can be flexibly set according to the regulations.

Next, a modification of the first embodiment will be described with reference to FIGS. 18 and 19.
FIG. 18 is a side view showing the arrangement of a control board 120 provided in a brush motor 100B according to a modification of the first embodiment of the present invention. FIG. 19 is a detailed view of the arrangement of the control board 120 provided in the brush motor 100B according to the modification of the first embodiment of the present invention. With the exception of the arrangement position of the control board 120, the brush motors 100B according to the modification of the first embodiment are configured in the same manner as the brush motors 100 according to the first embodiment described above.

Further, according to the first embodiment, even if the power supply voltage of the motor is increased (for example, 42 V, 48 V, etc.), the substance supplied to the motor by adjusting the duty of the PWM signal in PWM control The typical power supply voltage can be maintained at a conventional voltage (e.g. 12 V). Therefore, it is possible to flexibly cope with any power supply voltage, and it is possible to continue to use the conventional wiper motor even if the power supply voltage is increased. Therefore, it is not necessary to take measures to increase the voltage of the motor.
Moreover, according to the first embodiment, it is possible to realize a brush motor having desired characteristic requirements required for the wiper device without requiring a design change on the vehicle side.

  As shown in FIG. 18, in the present modification, the control substrate 120 is disposed inside the housing portion GH of the speed reduction mechanism portion G of the brush motor 100B. Specifically, as shown in FIG. 19, the control substrate 120 is an inner surface of a bottom cover (iron or resin cover) that constitutes the housing portion GH of the brush motor 100B, and the reduction mechanism portion of the brush motor 100B. It is arrange | positioned in the site | part which does not interfere in operation | movement of the worm wheel gear of G, etc. That is, the control board 120 is a bottom cover of the housing portion GH which covers the worm wheel gear and the like so as not to come into contact with the worm wheel gear and the like in the reduction gear portion G which the rotational shaft of the rotary armature extends and engages. The inner wall surface and the surface of the substrate are mounted opposite to the inner wall surface of the.

  Also according to this modification, it is possible to miniaturize the brush motor while achieving multipolarization of the magnetic poles of the brush motor. In addition, since the rotational speed of the motor main body 110 is controlled by PWM control as in the above-described first embodiment, the rotational speed can be changed without switching the brushes. In addition, according to the present modification, since the control substrate 120 can be disposed regardless of the placement of the brushes, there is no restriction due to the placement position of the brushes.

  Also, the program for realizing the operation of the microcomputer 1208 in FIGS. 2 and 15 to 16 described above is recorded in a computer readable recording medium, and the program recorded in the recording medium is recorded in a computer system. The execution process may be performed by reading and executing. Note that the “computer system” referred to here may include an OS and hardware such as peripheral devices.

  The "computer system" also includes a homepage providing environment (or display environment) if the WWW system is used. In addition, “computer readable recording medium” refers to flexible disks, magneto-optical disks, ROMs, writable nonvolatile memories such as flash memories, portable media such as CD-ROMs, hard disks incorporated in computer systems, etc. Storage devices.

The program may be transmitted from a computer system in which the program is stored in a storage device or the like to another computer system via a transmission medium or by transmission waves in the transmission medium.
Further, the program may be for realizing a part of the functions described above.
Furthermore, it may be a so-called difference file (difference program) that can realize the above-described functions in combination with a program already recorded in the computer system.

  DESCRIPTION OF SYMBOLS 100, 100A, 100B ... Brush motor, 110 ... Motor main-body part, 110H ... Brush holder, 111A, 111B, 111C, 111D, 111F ... Brush, 120 ... Control board, 130 ... Current detection element, 141, 143 ... Diode , 150: relay plate, 1201, 1201 A: duty control unit, 1201a: conduction time measurement counter, 1202, 1202A: PWM signal generation unit, 1203: drive unit, 1204: drive transistor, 1204a: body diode, 205: over current detection Unit 1208 Microcomputer 12011 Target current setting unit 12012 Subtractor 12013 Current control unit 12014 Duty limit processing unit B Brake contact G Reduction mechanism unit GH Housing unit M motor , MH ... housing unit, S ... start contact.

Claims (6)

A multi-pole brush motor having four or more magnetic poles, which is used in a wiper device of a vehicle and generates a rotational force in one direction,
A rotating armature having a pressure equalization line,
A commutator provided to the rotating armature;
The first and the brush and a second brush which contacts the commutator,
A first circuit connected to the first brush or the second brush;
One end of the power supply is connected to the first circuit, and interlocked with an operation switch provided on the vehicle, the power supply is connected between the first brush and the second brush via the first circuit. Second and third circuits for supplying a voltage;
The voltage signal in the second circuit and the third circuit is detected, and based on the detected voltage signal, the duty of the voltage pulse applied between the first brush and the second brush is selected. The duty control unit
A PWM signal generation unit which outputs a PWM signal which is a pulse train of the duty according to the selected duty supplied from the duty control unit;
It is connected between any one of the first brush and the second brush and any one of a power source and a ground, turned on and off by the PWM signal, and between the first brush and the second brush. A drive transistor that applies a voltage of the power supply as the voltage pulse;
A current detection element for detecting the current value of the current flowing through the drive transistor;
The duty control unit controls the duty to reduce the current flowing through the brush motor so that the amplitude of the torque ripple of the current detected by the current detection element is reduced and the current value converges to a preset target current value. A brush motor characterized by adjusting. In the brush motor according to claim 1,
The brush motor according to claim 1, further comprising: a diode provided in only one of the second circuit and the third circuit. The duty control unit
As the target current value, an average current value which is an average value of the current flowing through the drive transistor detected by the current detection element over a predetermined period is set.
The brush motor according to claim 1 or 2 , wherein the duty is controlled to limit the current flowing through the brush motor within a predetermined range based on the average current value. The duty control unit
Brush motor according to claim 1 or claim 2, characterized in that the as the target current value, set the rated current of the brush motor. The device further includes an overcurrent detection unit that determines whether the current value detected by the current detection element exceeds a preset current value.
The duty control unit
When the current value detected by the current detection element exceeds the set current value, clocking is started, and a set time set corresponding to a rise in temperature of the brush motor due to the flow of the set current value, When detecting that the current value exceeds the set current value is measured time flow exceeds claim 4 the duty cycle of the PWM signal from claim 1, characterized in that a duty in which the brush motor is stopped The brush motor according to any one of the above. It is a brush motor used for car wiper devices,
The duty control unit
According to the desired specification of the load torque of the brush motor, the set value of the duty of the PWM signal at the time of low speed operation and high speed operation of the wiper in wiping the windshield is changed. brush motor according to any one of claims 1 to 5.

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