JP6536719B2 - Wiper controller - Google Patents

Description

  The present invention relates to a wiper control device.

  When the resistance of the wiper blade reciprocating on the windshield glass increases due to snow accumulation on the windshield glass, the load on the wiper motor for driving the wiper blade increases, and the control circuit of the wiper motor and the wiper motor is easily overheated. In such a case, in order to prevent the wiper motor and the control circuit from being damaged, the overheat state may be canceled by temporarily stopping the operation of the wiper motor.

  However, when the wiper motor is stopped while the vehicle is traveling, wiping of the windshield glass by the wiper blade is interrupted, and there is a possibility that the visibility in front of the vehicle can not be secured. Patent Document 1 discloses a wiper control device that eliminates an overheated state of a wiper motor and a control circuit by gradually reducing the speed at which a wiper blade reciprocates at the time of overheating.

  In the wiper control device described in Patent Document 1, for example, when an overheating state is detected during Hi mode in which the wiper blade operates at high speed, the operation speed of the wiper blade is Lo mode slower than Hi mode, and further intermittent. Changed to the INT mode of operation to eliminate the overheat condition.

JP 2008-238899 A

  However, the wiper control device described in Patent Document 1 performs processing for stepwise improving the speed at which the wiper blade reciprocates when the overheating of the wiper motor and the control circuit disappears. There is a problem that it takes time to return to the speed.

  The present invention has been made in view of the above, and it is an object of the present invention to provide a wiper control device that quickly restores the operating speed of the wiper blade after the overheat state is eliminated.

  In order to solve the above-mentioned subject, a wiper control device according to claim 1 detects temperature of a brushless motor which makes a wiper blade reciprocate, or a drive circuit which generates a voltage to be supplied to the brushless motor by pulse width modulation. A temperature detection unit controls pulse width modulation of the drive circuit so that the brushless motor rotates at a rotational speed according to the position of the wiper switch, and the temperature detected by the temperature detection unit is an upper limit value of a predetermined range. In the above case, the pulse width modulation of the drive circuit is controlled so that the rotational speed of the brushless motor is lower than the rotational speed according to the position of the wiper switch, and the rotational speed of the brushless motor is driven The temperature detected by the temperature detection unit after the elapse of a predetermined time from when it is reduced by the control of the pulse width modulation of the circuit When the rotational speed of the brushless motor is further reduced by the control of pulse width modulation of the drive circuit when it is above the upper limit of the predetermined range, the temperature detected by the temperature detection unit is above the upper limit of the predetermined range In this case, the rotational speed of the brushless motor is reduced stepwise to the minimum speed, and the rotational speed of the brushless motor is reduced when the temperature detected by the temperature detection unit becomes lower than the lower limit value of the predetermined range. And a control unit configured to control pulse width modulation of the drive circuit so as to quickly return to the rotational speed corresponding to the switch position of the wiper switch.

  According to this wiper control device, since the overheat state is eliminated by gradually reducing the rotational speed of the motor in the case of the overheat state, the operation speed of the wiper blade is suddenly reduced and the window seal and the glass It prevents the wiping from becoming insufficient.

  Further, according to this wiper device, when the overheat state is eliminated, the rotational speed of the motor, which has been reduced in stages, is restored at once to the rotational speed according to the switch position of the wiper switch. After that, the operating speed of the wiper blade can be quickly restored.

  The wiper control device according to claim 2 is the wiper control device according to claim 1, further comprising: a rotation angle detection unit that outputs a signal according to the rotation angle of the output shaft of the brushless motor, wherein the control unit The position of the wiper blade is calculated based on the signal output from the rotation angle detection unit, and the rotational speed of the brushless motor is reduced when the calculated position of the wiper blade is the reverse position, or the wiper switch Return to the rotational speed according to the switch position of at once.

  According to this wiper control device, when the wiper blade reaches the reverse position, the rotational speed of the brushless motor is reduced or restored, so that the operating speed of the wiper blade unnaturally changes while wiping the windshield glass. Can be prevented.

  The wiper control device according to claim 3 is the wiper control device according to claim 1, wherein the control unit is configured to control the temperature detected by the temperature detection unit to be equal to or higher than an upper limit value of the predetermined range. The rotational speed of the brushless motor is reduced below that corresponding to the switch position of the wiper switch, and the temperature detected by the temperature detection unit after a predetermined time has elapsed since the rotational speed was decreased. In the case where the rotational speed of the brushless motor is further reduced when the temperature is higher than the upper limit, and the temperature detected by the temperature detection unit becomes higher than the high temperature threshold higher than the upper limit of the predetermined range, The rotational speed of the brushless motor is reduced when the rotational speed is reduced to the minimum speed and the temperature detected by the temperature detection unit becomes lower than the lower limit value of the predetermined range. Once to return to the rotation speed corresponding to the switch position of Ipasuitchi.

  According to this wiper control device, when the temperature detected by the temperature detection unit is equal to or higher than the high temperature threshold equal to or higher than the upper limit value of the predetermined range, the rotational speed of the brushless motor is reduced to the minimum speed to eliminate the overheat state. When the overheat state disappears, the rotational speed of the brushless motor is rapidly returned to the rotational speed corresponding to the switch position of the wiper switch. As a result, the operating speed of the wiper blade can be quickly restored after the overheat state is eliminated.

It is the schematic which shows the structure of the wiper apparatus containing the wiper control apparatus which concerns on embodiment of this invention. It is the schematic which shows the position of the sensor of the wiper motor which concerns on embodiment of this invention. FIG. 3 is a cross-sectional view showing a cross section of the wiper motor taken along line A-A shown in FIG. 2; It is a block diagram showing an outline of an example of composition of a wiper control device concerning an embodiment of the invention. It is the schematic at the time of making the time selection position of the wiper switch of the wiper control apparatus which concerns on embodiment of this invention, the thermistor temperature which the thermistor detected, and the operation mode of the actually operated wiper be compared on the same time axis. It is the flow chart which showed an example of wiper operation speed control processing of the wiper control device concerning an embodiment of the invention.

  FIG. 1 is a schematic view showing a configuration of a wiper apparatus 100 including a wiper control apparatus 10 according to the present embodiment. The wiper device 100 is for wiping the windshield glass 12 provided in a vehicle such as a passenger car, for example, and the pair of wipers 14 and 16, the wiper motor 18, the link mechanism 20, and the wiper control device 10 And have.

  The wipers 14 and 16 are composed of wiper arms 24 and 26 and wiper blades 28 and 30, respectively. The proximal ends of the wiper arms 24 and 26 are respectively fixed to pivot shafts 42 and 44 described later, and the wiper blades 28 and 30 are respectively fixed to distal ends of the wiper arms 24 and 26.

  In the wipers 14 and 16, the wiper blades 28 and 30 reciprocate on the windshield glass 12 in accordance with the operation of the wiper arms 24 and 26, and the wiper blades 28 and 30 wipe the windshield glass 12.

  The wiper motor 18 is a brushless DC motor including a stator that is an electromagnet that generates a rotating magnetic field by controlling an applied voltage in the circumferential direction of a rotor configured by permanent magnets. The wiper motor 18 has an output shaft 32 that can be rotated forward and reverse via a reduction mechanism 52 mainly composed of a worm gear, and the link mechanism 20 includes a crank arm 34, a first link rod 36, and a pair of pivots The levers 38 and 40, the pair of pivot shafts 42 and 44, and the second link rod 46 are provided.

  One end of the crank arm 34 is fixed to the output shaft 32, and the other end of the crank arm 34 is operatively connected to one end of the first link rod 36. Also, the other end of the first link rod 36 is operatively connected to a point near an end different from the end having the pivot shaft 42 of the pivot lever 38, and the end having the pivot shaft 42 of the pivot lever 38 The two ends of the second link rod 46 are respectively operatively connected to different ends and the end of the pivot lever 40 corresponding to the end of the pivot lever 38.

  Further, the pivot shafts 42, 44 are movably supported by a pivot holder (not shown) provided on the vehicle body, and the end of the pivot levers 38, 40 having the pivot shafts 42, 44 is via the pivot shafts 42, 44. The wiper arms 24 and 26 are respectively fixed.

  In the wiper device 100 including the wiper control device 10 according to the present embodiment, when the output shaft 32 is rotated forward and reverse at a rotation angle θ1 of a predetermined range, the rotational force of the output shaft 32 is transmitted via the link mechanism 20. The wiper blades 28 and 30 reciprocate between the lower reversing position P2 and the upper reversing position P1 on the windshield glass 12 according to the reciprocation of the wiper arms 24 and 26. The value of θ1 can take various values depending on the configuration of the link mechanism of the wiper control device and the like, but in the present embodiment, it is 140 ° as an example.

  In the wiper device 100 including the wiper control device 10 according to the present embodiment, as shown in FIG. 1, when the wiper blades 28 and 30 are positioned at the storage position P3, the crank arm 34 and the first link rod 36 are in a linear configuration.

  The storage position P3 is provided below the lower inversion position P2. When the output shaft 32 rotates by θ2 from the state where the wiper blades 28 and 30 are at the lower reversing position P2, the wiper blades 28 and 30 move to the storage position P3. The value of θ2 can take various values depending on the configuration of the link mechanism of the wiper device and the like, but in this embodiment, it is 10 ° as an example. When θ2 is “0”, the lower reversal position P2 and the storage position P3 coincide with each other, and the wiper blades 28 and 30 stop at the lower reversal position P2 and are stored.

  A wiper control device 10 for controlling the rotation of the wiper motor 18 is connected to the wiper motor 18. The wiper control device 10 according to the present embodiment controls, for example, a rotation angle sensor 54 for detecting the rotation speed and rotation angle of the output shaft 32 of the wiper motor 18, and PWM (Pulse Width Modulation) control of the current for operating the wiper motor 18. , And a Hall sensor 72 for detecting the position of the rotor of the wiper motor 18. Further, a thermistor 102 for detecting the temperature of the substrate is mounted on the substrate of the wiper control device 10.

  In the present embodiment, since the wiper motor 18 is a brushless DC motor, the drive circuit 56 includes an inverter circuit using a MOSFET as a switching element, and generates a voltage of a predetermined duty ratio by control of a microcomputer 58 described later.

  Since the wiper motor 18 according to the present embodiment has the reduction mechanism 52 as described above, the rotation speed and the rotation angle of the output shaft 32 are not the same as the rotation speed and the rotation angle of the wiper motor main body. However, in the present embodiment, since the wiper motor main body and the reduction mechanism 52 are integrally and inseparably configured, the rotational speed and the rotational angle of the output shaft 32 are regarded as the rotational speed and the rotational angle of the wiper motor 18 hereinafter. .

  The rotation angle sensor 54 is provided in the speed reduction mechanism 52 of the wiper motor 18 and converts a magnetic field (magnetic force) of a sensor magnet that rotates in conjunction with the output shaft 32 into a current to detect it.

  The wiper control device 10 can calculate the position of the wiper blades 28 and 30 on the windshield glass 12 from the rotation angle of the output shaft 32 detected by the rotation angle sensor 54, and the rotation speed of the output shaft 32 can be calculated according to the position. The microcomputer 58 controls the drive circuit 56 to change. Further, the wiper control device 10 has a memory 48 storing data and programs used for control of the drive circuit 56, and a wiper switch 50 is connected to the microcomputer 58 of the wiper control device 10. The memory 48 is, for example, a non-volatile storage device such as an HDD (Hard Disk Drive) or a flash memory.

  The microcomputer 58 calculates the position of the rotor of the wiper motor 18 based on the signal output from the hall sensor 72. The microcomputer 58 also controls the drive circuit 56 to generate a voltage having a phase based on the calculated position of the rotor.

  The wiper switch 50 is a switch that turns on or off the power supplied to the wiper motor 18 from the battery of the vehicle, which is a power supply. The wiper switch 50 has a Lo mode selection position for operating the wiper blades 28 and 30 at a low speed, a Hi mode selection position for operating at a high speed, an INT mode selection position for intermittently operating at fixed intervals, and a storage (stop) mode selection position. Can be switched to Further, it outputs to the microcomputer 58 a signal of a rotational speed command corresponding to the selected position of each mode.

  When a signal output from the wiper switch 50 according to the selected position of each mode is input to the microcomputer 58, the microcomputer 58 performs control corresponding to the output signal from the wiper switch 50.

  FIG. 2 is a schematic view showing the position of the sensor of the wiper motor 18 according to the present embodiment. As shown in FIG. 2, the wiper motor 18 is adjacent to a coil 86 for generating a rotating magnetic field in the circumferential direction of the rotor 88 composed of permanent magnets, and in the axial direction of the rotor 88 A hall sensor 72 for detecting is provided. If the wiper motor 18 is a three-phase DC brushless motor, the hall sensor 72 is provided for each of the U-phase, the V-phase, and the W-phase.

  Further, a worm 52A is formed at an end of a rotor shaft 88A extending from the rotor 88, and the worm 52A meshes with a worm wheel 52B integrally formed with the output shaft 32. In the present embodiment, the reduction mechanism 52 is configured by the worm 52A and the worm wheel 52B.

  A sensor magnet 70 is attached to the end of the output shaft 32 opposite to the end to which the crank arm 34 is attached, and a rotation angle sensor 54 is provided opposite to the sensor magnet 70.

  FIG. 3 is a cross-sectional view showing a cross section of the wiper motor 18 taken along the line A-A shown in FIG. The worm 52A is helically formed along the axial direction of the rotor shaft 88A. Further, the worm wheel 52B is formed in a disk shape, and a spur tooth-shaped tooth groove is formed along the circumferential direction. By meshing the spiral groove of the worm 52A and the tooth groove of the worm wheel 52B, it is possible to reduce the rotation of the rotor 88 at a predetermined reduction ratio and transmit it to the output shaft 32. A sensor magnet 70 is attached to the center of the bottom surface of the worm wheel 52B corresponding to the end of the output shaft 32.

  In the space between the upper housing 78A and the lower housing 78B directly below the reduction mechanism 52 in the upper housing 78A, the substrate 90 of the wiper control device 10 according to the present embodiment is provided to be attached to the wiper motor 18. ing. On the substrate 90, the microcomputer 58, the thermistor 102, the elements constituting the drive circuit 56, etc. are mounted. Further, in a portion of the substrate 90 facing the sensor magnet 70 provided at the end of the output shaft 32, a magnetic field of the sensor magnet 70 which changes with the rotation of the output shaft 32 is detected, and a signal indicating the change of the magnetic field A rotation angle sensor 54 is mounted to output.

  The position at which the thermistor 102 is mounted is influenced by the layout of the substrate 90 or the configuration of the circuit, but it is desirable that the mounting be performed near an element such as an element constituting the drive circuit 56 where heat generation is significant. In the present embodiment, as shown in FIG. 3, the thermistor 102 is mounted near the elements constituting the drive circuit 56. Also, if possible, a thermistor 102 may be mounted, for example, near the coil 86 of the wiper motor 18 to detect an overheated state of the wiper motor 18.

  FIG. 4 is a block diagram schematically showing an example of the configuration of the wiper control device 10 according to the present embodiment. The wiper motor 18 shown in FIG. 4 is, for example, a three-phase six-pole DC brushless motor. The rotor 88 of the wiper motor 18 is comprised of three S pole and N pole permanent magnets. The magnetic field of the rotor 88 is detected by the Hall sensor 72. The Hall sensor 72 may detect the magnetic field of a sensor magnet provided separately from the rotor 88 in accordance with the polarity of the permanent magnet of the rotor 88. The Hall sensor 72 detects the magnetic field of the rotor 88 or sensor magnet as a magnetic field that indicates the position of the rotor 88.

  A signal output from the hall sensor 72 is input to a microcomputer 58 which is a control circuit. The microcomputer 58 is an integrated circuit, and the power supplied from the power supply 80 by the standby circuit 60 is controlled.

  A signal input from the Hall sensor 72 to the microcomputer 58 is a sine wave analog signal, but is converted into a rectangular wave digital signal by the Hall sensor edge detection unit 66 in the microcomputer 58. In addition, the Hall sensor edge detection unit 66 detects an edge where the digital signal changes from high level to low level or from low level to high level.

  The digital signal and edge information are input to the motor position estimation unit 64, and the motor position estimation unit 64 calculates the position of the rotor 88. Information on the calculated position of the rotor 88 is input to the energization control unit 68.

  A signal for instructing the rotational speed of the wiper motor 18 (rotor 88) is input from the wiper switch 50 to the command value calculation unit 62 of the microcomputer 58. The command value calculation unit 62 extracts a command related to the rotational speed of the wiper motor 18 from the signal input from the wiper switch 50, and inputs the command to the energization control unit 68. Further, a signal of the rotation angle sensor 54 is also input to the energization control unit 68. The energization control unit 68 calculates the position of the wiper blades 28 and 30 on the windshield glass 12 from the signal of the rotation angle sensor 54.

  The energization control unit 68 calculates the phase of the voltage that changes according to the position of the rotor 88 calculated by the motor position estimation unit 64 and the positions of the wiper blades 28 and 30, and is instructed by the calculated phase and the wiper switch 50. Based on the rotational speed of the rotor 88, the drive duty value is determined. Further, the energization control unit 68 performs PWM control of generating a PWM signal which is a pulse signal corresponding to the drive duty value and outputting the PWM signal to the drive circuit 56.

  The drive circuit 56 is configured of a three-phase (U-phase, V-phase, W-phase) inverter. As shown in FIG. 4, the drive circuit 56 includes three N-channel field effect transistors (MOSFETs) 74U, 74V, and 74W (hereinafter referred to as "FETs 74U, 74V, and 74W"), respectively, as upper stage switching elements. It has three N-channel field effect transistors (MOSFETs) 76U, 76V, 76W (hereinafter referred to as "FETs 76U, 76V, 76W") as lower stage switching elements. The FETs 74U, 74V, 74W and the FETs 76U, 76V, 76W are collectively referred to as "FET 74" and "FET 76" when there is no need to distinguish them individually, and when it is necessary to distinguish them, "U" , "V", "W" with the symbols attached.

  Of the FET 74 and the FET 76, the source of the FET 74U and the drain of the FET 76U are connected to the terminal of the coil 86U, and the source of the FET 74V and the drain of the FET 76V are connected to the terminal of the coil 86V. The source of the FET 74W and the FET 76W The drain is connected to the terminal of the coil 86W.

  The gates of the FET 74 and the FET 76 are connected to the conduction control unit 68, and a PWM signal is input. The FET 74 and the FET 76 are turned on when an H level PWM signal is input to their gates, and a current flows from the drain to the source. In addition, when an L level PWM signal is input to the gate, the transistor is turned off, and no current flows from the drain to the source.

  In the present embodiment, the thermistor 102 is mounted near the drive circuit 56 configured by the FETs 74U, 74V, 74W, 76U, 76V, and 76W which are switching elements. The thermistor 102 is an element whose resistance value changes with temperature, and constitutes a voltage dividing circuit together with the resistor 104. The voltage divided by the resistor 104 and the thermistor 102 is input to the conduction control unit 68. The conduction control unit 68 detects the temperature of the substrate 90 on which the FETs 74U, 74V, 74W, 76U, 76V, 76W are mounted based on the input voltage, and the temperature of the substrate 90 becomes equal to or higher than a predetermined threshold In this case, the rotational speed of the wiper motor 18 is reduced to eliminate overheating of the substrate 90 and the like.

  Further, in the wiper control device 10 of the present embodiment, the power supply 80, the noise prevention coil 82, the smoothing capacitors 84A and 84B, and the like are configured. The power supply 80, the noise prevention coil 82, and the smoothing capacitors 84A and 84B substantially constitute a DC power supply.

  FIG. 5 shows the case where the mode selection position of the wiper switch 50 of the wiper control device 10 according to the present embodiment, the thermistor temperature detected by the thermistor 102, and the operation mode of the actually operated wiper are compared on the same time axis. FIG.

  As shown in FIG. 5, in the present embodiment, a predetermined range 110 in which the first threshold is the lower limit and the second threshold is the upper limit is set, and the second threshold is the upper limit of the thermistor 110. When it becomes above, the rotational speed of the wiper motor 18 is decreased. Thereafter, the rotational speed of the wiper motor 18 is gradually decreased until the thermistor temperature falls below a first threshold which is the lower limit value of the predetermined range 110. When the thermistor temperature becomes equal to or higher than the third threshold higher than the second threshold, the rotational speed of the wiper motor 18 is reduced to the rotational speed in the INT mode which is the minimum speed. By decreasing the rotational speed of the wiper motor 18, when the temperature of the thermistor falls below the first threshold, the rotational speed of the wiper motor 18 is rapidly returned to the rotational speed according to the position of the wiper switch 50.

In Figure 5, the wiper switch 50 at time _{t 0} is switched to the Hi mode, the wiper blades 28, 30 reciprocates in the operating speed of the Hi mode. At time t _1, reaches the second threshold thermistor temperature exceeds the first threshold value, the substrate 90 is in a superheated state. In the present embodiment, when the thermistor temperature becomes equal to or higher than the second threshold, the rotational speed of the wiper motor 18 is reduced so that the operating speed of the wiper blades 28 and 30 becomes an intermediate speed between the Hi mode and the Lo mode. . Specifically, the microcomputer 58 controls the drive circuit 56 to generate a voltage for reducing the rotational speed of the wiper motor 18 lower than the rotational speed corresponding to the mode selection position of the wiper switch 50.

Thermistor temperature at time t ₂ to time t ₁ from the time T1 has elapsed, still in the case of more than the second threshold value, the rotational speed of the wiper motor 18 so that the operation speed of the wiper blade 28, 30 is the operating speed of the Lo mode Reduce Specifically, the microcomputer 58 controls the driving circuit 56 to generate a voltage for reducing than in the case of the rotational speed of the wiper motor 18 from time t ₁ to t _2.

  Further, the timing for reducing the rotational speed of the wiper motor 18 is when the wiper blades 28 and 30 reach the upper reversing position P1 or the lower reversing position P2. By changing the rotational speed of the wiper motor 18 at the reverse position, the operating speed of the wiper blades 28 and 30 during wiping of the windshield glass 12 is prevented from changing unnaturally. In the present embodiment, the microcomputer 58 calculates the positions of the wiper blades 28 and 30 on the windshield glass 12 based on the signal output from the rotation angle sensor 54, and the calculated positions of the wiper blades 28 and 30 are up. At the reverse position P1 or the lower reverse position P2, the rotational speed of the wiper motor 18 is reduced.

After the operation speed of the wiper blades 28, 30 to Lo mode time t _2, the if the thermistor temperature reaches the third threshold value or more higher than the second threshold value, the operation speed of the wiper blades 28, 30 to the INT mode Thus, the rotational speed of the wiper motor 18 is reduced. Further, the thermistor temperature at the time t ₃ when the time T2 from the time t ₂ has elapsed, even if still greater than or equal to the second threshold value, the rotational speed of the wiper motor 18 so that the operation speed of the wiper blade 28, 30 is INT mode Reduce.

Thermistor temperature is equal to or larger than a second threshold value equal to or larger than the third threshold value or the time t ₂ from time T2 after the lapse, the microcomputer 58 decreases the rotational speed of the wiper motor 18 to the rotational speed of the INT mode is the lowest speed The drive circuit 56 is controlled to generate a voltage for driving.

In Figure 5, the thermistor temperature at time t ₄ has decreased to below a first threshold value. In the present embodiment, when the thermistor temperature becomes equal to or lower than the first threshold value, the operating speed of the wiper blades 28 and 30 is restored at once to the operating speed of the operating mode indicated by the mode selection position of the wiper switch 50. In the case of FIG. 5, since the mode selection position of the wiper switch 50 is in the Hi mode, when the thermistor temperature becomes lower than the first threshold, the wiper motor 28 is set such that the operating speed of the wiper blades 28 becomes the operating speed in Hi mode. Increase the rotation speed of Specifically, the microcomputer 58 controls the drive circuit 56 to generate a voltage for setting the rotational speed of the wiper motor 18 to the rotational speed in the Hi mode.

  It should be noted that, as in the case of the reduction of the operating speed described above, it is determined from the detection result of the rotation angle sensor 54 that the wiper blades 28 and 30 have reached the upper reversing position P1 or the lower reversing position P2 If you do. Further, since the first threshold, the second threshold and the third threshold are different depending on the type of the wiper device, they are specifically determined by simulation using a computer and experiments using a real machine.

  FIG. 6 is a flowchart showing an example of the wiper operation speed control process of the wiper control device 10 according to the present embodiment. Since the wiper switch 50 is turned on (Hi mode) in step 600, in step 602, the wiper blades 28 and 30 are operated in the Hi mode.

  In step 604, it is determined whether or not the thermistor temperature has become equal to or higher than the second threshold. If the determination is affirmative, the operation speed of the wiper blades 28 and 30 is set to an intermediate speed between Hi mode and Lo mode in step 606. . In the case of a negative determination in step 604, no overheating has occurred, so the procedure shifts to step 618 to continue the operation in the Hi mode.

  In step 608, after the time T1 has elapsed since the thermistor temperature became equal to or higher than the second threshold value in step 604, the thermistor temperature is further raised by determining whether or not the thermistor temperature is equal to or higher than the second threshold value. Determine if there is a risk. In the case of a positive determination in step 608, in step 610, the operating speed of the wiper blades 28 and 30 is set to the speed of Lo mode.

  In step 612, it is determined whether or not the thermistor temperature is equal to or higher than a third threshold value. In the case of a positive determination, in step 614, the operating speed of the wiper blades 28 and 30 is set to the speed of INT mode. In the case of a negative determination in steps 608 and 612, the procedure proceeds to step 616.

  In step 616, it is determined whether or not the thermistor temperature has become equal to or less than the first threshold value. If the determination is affirmative, step 618 is Hi in which the operation speed of the wiper blades 28 and 30 is indicated by the mode selection position of the wiper switch 50. Return to mode speed and return processing.

  If the determination in step 616 is negative, in step 620, it is determined whether the time T2 has elapsed after the operating speed of the wiper blades 28 and 30 is reduced to the operating speed in Lo mode in step 610. If the determination in step 620 is affirmative, the procedure proceeds to step 614 to reduce the operating speed of the wiper blades 28 and 30 to the operating speed in the INT mode. In the case of a negative determination in step 620, the procedure is returned to step 612, and it is determined whether or not the thermistor temperature exceeds a third threshold.

  As described above, according to the present embodiment, it is determined that the overheat state has been eliminated when the thermistor temperature becomes a threshold value lower than the threshold value for determining whether the overheat state has occurred. In such a case, since the wiper motor and the wiper motor and the control motor of the wiper motor have been completely overheated, the operating speed of the wiper blade can be quickly returned.

DESCRIPTION OF SYMBOLS 10 Wiper control device 12 Windshield glass 14, 16 Wiper 18 Wiper motor 20 Link mechanism 24, 26 Wiper arm 28, 30 Wiper blade 32 Output shaft 34 Crank arm DESCRIPTION OF SYMBOLS 36 ... Link rod, 38, 40 ... Pivot lever, 42, 44 ... Pivot axis, 46 ... Link rod, 48 ... Memory, 50 ... Wiper switch, 52 ... Deceleration mechanism, 52A ... Worm, 52B ... Worm wheel, 54 ... Rotation Angle sensor 56 Drive circuit 58 Microcomputer 60 Standby circuit 62 Command value calculation unit 64 Motor position estimation unit 66 Hall sensor edge detection unit 68 Conduction control unit 70 Sensor magnet , 72 ... Hall sensor, 74 (74 U, 74 V, 74 W) ... FET, 76 (76 U 76V, 76W) ... FET, 78A ... upper housing, 78B ... lower housing, 80 ... power supply, 82 ... noise prevention coil, 84A, 84B ... smoothing capacitor, 86 (86U, 86V, 86W) ... coil, 88 ... rotor, 88A ... Rotor shaft, 90 ... board, 100 ... wiper device, 102 ... thermistor, 104 ... resistance, 110 ... predetermined range, P1 ... upper reversal position, P2 ... lower reversal position, P3 ... storage position, θ1 ... rotation angle

Claims (3)

A brushless motor that causes a wiper blade to reciprocate, or a temperature detection unit that detects the temperature of a drive circuit that generates a voltage supplied to the brushless motor by pulse width modulation;
The pulse width modulation of the drive circuit is controlled such that the brushless motor rotates at a rotational speed corresponding to the position of the wiper switch, and the temperature detected by the temperature detection unit becomes equal to or higher than the upper limit value of the predetermined range. The pulse width modulation of the drive circuit is controlled such that the rotation speed of the brushless motor is lower than the rotation speed according to the position of the wiper switch, and the pulse width modulation of the rotation speed of the brushless motor is performed. Control of the pulse width modulation of the drive circuit when the temperature detected by the temperature detection unit is equal to or higher than the upper limit value of the predetermined range after a predetermined time has elapsed since the time of reduction by the control of. When the temperature detected by the temperature detection unit is equal to or higher than the upper limit value of the predetermined range after the The rotational speed of the brushless motor is reduced according to the switch position of the wiper switch when the rotational speed is reduced stepwise to the minimum speed and the temperature detected by the temperature detection unit becomes lower than the lower limit value of the predetermined range. A control unit that controls pulse width modulation of the drive circuit so as to restore at once the rotational speed.
Wiper control device including. A rotation angle detection unit that outputs a signal according to the rotation angle of the output shaft of the brushless motor;
The control unit calculates the position of the wiper blade based on the signal output from the rotation angle detection unit, and reduces the rotational speed of the brushless motor when the calculated position of the wiper blade is the reverse position. The wiper control device according to claim 1, wherein the rotational speed is rapidly returned to the rotational speed according to the switch position of the wiper switch.   The control unit reduces the rotational speed of the brushless motor to be lower than the rotational speed according to the switch position of the wiper switch when the temperature detected by the temperature detection unit becomes equal to or higher than the upper limit value of the predetermined range. The rotational speed of the brushless motor is further reduced when the temperature detected by the temperature detection unit is equal to or higher than the upper limit value of the predetermined range after a predetermined time has elapsed from when the rotational speed is reduced. The rotational speed of the brushless motor is reduced to the minimum speed when the temperature detected by the part becomes equal to or higher than the high temperature threshold higher than the upper limit value of the predetermined range, and the temperature detected by the temperature detection part is the predetermined The rotational speed of the brushless motor is rapidly returned to the rotational speed according to the switch position of the wiper switch when the value falls below the lower limit value of the range. Of the wiper control device.