JP2015051709A - Wiper device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiper device capable of detecting a position of a wiper blade and the rotation speed of an output shaft from a detection result of one sensor.SOLUTION: A rotation angle sensor 54 detects a magnetic field of a magnet rotating with an output shaft 32, and outputs changes of the magnetic field of the magnet due to rotations as changes of voltage. A microcomputer 58 calculates a rotation angle of the output shaft 32 indicating positions of wiper blades 28 and 30 on a windshield 12 from a voltage value obtained by sampling voltage outputted from the rotation angle sensor 54 at predetermined intervals, calculates the rotation speed of the output shaft 32 from the rotation angle of the output shaft 32 calculated after predetermined time has passed and the predetermined time. The rotations of a wiper motor 18 is controlled on the basis of the calculated rotation angle and rotation speed of the output shaft 32.

Description

  The present invention relates to a wiper device.

  The wiper device wipes the glass surface by reciprocatingly rotating a wiper blade on a window glass such as a front window or a rear window of a vehicle. In order for the wiper device to reverse the wiper blade at a predetermined position and rotate the wiper blade at a predetermined speed according to the position on the window glass, the position of the wiper blade on the window glass and the wiper blade are rotated. It is necessary to detect the rotational speed of the output shaft of the wiper motor.

  In Patent Document 1, a plurality of permanent magnets are arranged at equal intervals on two circular tracks coaxial with the output shaft of the wiper motor, and the magnetic field of these permanent magnets is detected by a hall sensor to determine the position of the wiper blade and the wiper motor. A wiper device that detects the rotational speed of an output shaft is disclosed.

  In the wiper device described in Patent Document 1, the position of the wiper blade is detected by detecting the magnetic field of the permanent magnet arranged on the inner circular orbit among the permanent magnets arranged on two circular orbits coaxial with the output shaft. And the rotational speed of the output shaft is detected by detecting the magnetic field of the permanent magnet disposed on the outer circular orbit. The inner circular track and the outer circular track have different intervals between the permanent magnets arranged for the detection of the position of the wiper blade and the detection of the rotational speed of the output shaft.

Japanese Patent No. 4314031

  However, the wiper device described in Patent Document 1 must include a hall sensor that detects the magnetic field of the permanent magnet on the inner circular orbit and a hall sensor that detects the magnetic field of the permanent magnet on the outer circular orbit. There is a problem that the configuration of the apparatus becomes complicated. Further, in the wiper device described in Patent Document 1, the Hall sensor that detects the magnetic field of the inner permanent magnet uses the magnetic sensor of the outer permanent magnet, and the Hall sensor that detects the magnetic field of the outer permanent magnet uses the inner permanent magnet. There was a risk of erroneous detection of each magnetic field. In order to avoid such erroneous detection, it is necessary to optimize the magnetic field of the permanent magnets arranged in each circular orbit, the position of each Hall sensor, etc., and there is a problem that the design and manufacture of the product becomes complicated. It was.

  Further, in the wiper device described in Patent Document 1, in order to detect the position of the wiper blade more accurately, it is necessary to provide many more permanent magnets on the circular orbit. Since there is a limit to mounting a large number of permanent magnets on a limited circular orbit, the wiper device described in Patent Document 1 has a problem that it is difficult to improve the accuracy of detecting the position of the wiper blade. there were.

  The present invention has been made in view of the above, and an object thereof is to provide a wiper device capable of detecting the position of the wiper blade and the rotational speed of the output shaft from the detection result of one sensor.

  In order to solve the above-mentioned object, a wiper device according to the first aspect of the present invention includes a wiper blade that reciprocates and wipes the surface of a window glass, and the wiper blade is connected to an output shaft via a link mechanism. A wiper motor that reciprocally rotates the wiper blade by rotation of the output shaft, a magnet that rotates in conjunction with the rotation of the output shaft, a magnetic field of the magnet is detected, and a change in the magnetic field of the magnet due to the rotation is detected by a voltage. A rotation angle of the output shaft indicating the position of the wiper blade on the window glass from a voltage value obtained by sampling the voltage output by the detection means at a predetermined sampling interval; The rotation speed of the output shaft is calculated from the rotation angle of the output shaft calculated over a predetermined time and the predetermined time, and the calculated rotation angle of the output shaft And based on the rotational speed and a control means for controlling the rotation of the wiper motor.

  In the wiper device according to the first aspect, the detection means that is a sensor outputs a change in the magnetic field of the magnet rotating in conjunction with the output shaft as a change in voltage. The control means calculates the rotation angle of the output shaft indicating the position of the wiper blade on the window glass from the voltage value obtained by sampling the voltage output by the detection means at a predetermined sampling interval.

  Further, the control means calculates the rotation speed of the output shaft from the rotation angle of the output shaft calculated over a predetermined time and the predetermined time, so that the position of the wiper blade and the output shaft are detected from the detection result of one sensor. Rotational speed can be detected.

  According to a second aspect of the present invention, in the wiper device according to the first aspect of the present invention, the wiper device further includes a storage unit that stores a speed map that defines a rotation speed of the output shaft according to a rotation angle of the output shaft, and the control unit Controls the rotation of the wiper motor so that the calculated rotation speed of the output shaft becomes the rotation speed defined in the speed map.

  According to this wiper device, the control means controls the rotation of the wiper motor so that the calculated rotation speed of the output shaft becomes the rotation speed of the speed map that defines the rotation speed of the output shaft according to the rotation angle. With this control, the wiper motor can be rotated at a rotational speed corresponding to the position of the wiper blade on the window glass.

  According to a third aspect of the present invention, in the wiper device according to the first or second aspect, the control means samples the voltage output from the detection means by shortening the predetermined sampling interval.

  According to this wiper apparatus, by changing the predetermined sampling interval as appropriate by rewriting the program of the control means, the predetermined sampling interval can be further shortened and the voltage output by the detecting means can be sampled. The accuracy of detecting the position of the wiper blade can be improved by further shortening the predetermined sampling interval.

It is the schematic which shows the structure of the wiper apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the rotation angle sensor which concerns on embodiment of this invention. It is a figure which shows an example of rotation of the magnet on the rotation angle sensor which concerns on embodiment of this invention. It is a figure which shows an example of the change of the voltage value which the rotation angle sensor in embodiment of this invention outputs. It is a figure which shows an example of voltage sampling in embodiment of this invention. It is a flowchart which shows an example of the position and rotation speed detection process in the wiper apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the speed map which prescribed | regulated the rotational speed of the output shaft of the wiper motor in this Embodiment.

  FIG. 1 is a schematic diagram illustrating a configuration of a wiper device 10 according to the present embodiment. The wiper device 10 is for wiping a front window 12 provided in a vehicle such as a passenger car, for example, and includes a pair of wipers 14 and 16, a wiper motor 18, a link mechanism 20, and a wiper control circuit 22. It has.

  The wipers 14 and 16 are constituted by wiper arms 24 and 26 and wiper blades 28 and 30, respectively. The base ends of the wiper arms 24 and 26 are fixed to pivot shafts 42 and 44, which will be described later, and the wiper blades 28 and 30 are fixed to the distal ends of the wiper arms 24 and 26, respectively.

  In the wipers 14, 16, the wiper blades 28, 30 reciprocate on the front window 12 as the wiper arms 24, 26 rotate, and the wiper blades 28, 30 wipe the front window 12.

  The wiper motor 18 has an output shaft 32 that can rotate forward and reverse via a speed reduction mechanism 52 mainly composed of a worm gear. The link mechanism 20 includes a crank arm 34, a first link rod 36, and a pair of pivots. The levers 38 and 40, a pair of pivot shafts 42 and 44, and a second link rod 46 are provided.

  One end side of the crank arm 34 is fixed to the output shaft 32, and the other end side of the crank arm 34 is rotatably connected to one end side of the first link rod 36. Further, the other end side of the first link rod 36 is rotatably connected to a position near the end different from the end having the pivot shaft 42 of the pivot lever 38, and the end of the pivot lever 38 having the pivot shaft 42 is connected. Both ends of the second link rod 46 are rotatably connected to the end different from the above and the end of the pivot lever 40 corresponding to the end of the pivot lever 38.

  The pivot shafts 42 and 44 are rotatably supported by a pivot holder (not shown) provided on the vehicle body, and the ends of the pivot levers 38 and 40 having the pivot shafts 42 and 44 are connected to the pivot shafts 42 and 44. The wiper arms 24 and 26 are fixed to each other.

  In the wiper device 10 according to the present embodiment, when the output shaft 32 rotates forward and backward within the rotation range θ1, the rotational force of the output shaft 32 is transmitted to the wiper arms 24 and 26 via the link mechanism 20, and this As the wiper arms 24 and 26 reciprocate, the wiper blades 28 and 30 reciprocate between the lower inversion position P2 and the upper inversion position P1 on the front window 12. The value of θ1 can take various values depending on the configuration of the link mechanism of the wiper device, etc., but is 120 ° as an example in the present embodiment.

  In the wiper 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 linear. It is configured to be made.

  The storage position P3 is provided below the lower inversion position P2. The wiper blades 28 and 30 are rotated to the retracted position P3 by rotating the output shaft 32 by θ2 from the state where the wiper blades 28 and 30 are in the lower inversion position P2. The value of θ2 can take various values depending on the configuration of the link mechanism of the wiper device, but in the present embodiment, it is set to 5 ° as an example. When θ2 is “0”, the lower inversion position P2 coincides with the storage position P3, and the wiper blades 28 and 30 are stopped and stored at the lower inversion position P2.

  A wiper control circuit 22 for controlling the rotation of the wiper motor 18 is connected to the wiper motor 18. If the wiper motor 18 is a brushless DC motor, the wiper control circuit 22 generates a current for operating the wiper motor 18 by PWM control and supplies the current to the wiper motor 18. A microcomputer 58 controls the drive circuit 56. And have. The wiper control circuit 22 stores data used by the microcomputer 58 for controlling the drive circuit 56 such as a speed map that defines the rotational speed of the output shaft 32 according to the position of the wiper blades 28 and 30 on the front window 12. The memory 60 is further included. The drive circuit 56 includes an inverter circuit using a MOSFET as a switching element, and outputs a current having a predetermined duty ratio by the inverter circuit.

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

  The rotation angle sensor 54 is provided in the speed reduction mechanism 52 of the wiper motor 18 or in the vicinity of the tip of the output shaft 32, and detects a change in the magnetic field (magnetic force) of the magnet 62 that rotates in conjunction with the output shaft 32 to change the voltage. Convert and output. In the wiper control circuit 22 according to the present embodiment, the microcomputer 58 determines the position of the wiper blades 28 and 30 on the front window 12 and the rotational speed of the output shaft 32 from the rotational angle of the output shaft 32 detected by the rotational angle sensor 54. Is calculated. Further, the wiper control circuit 22 controls the drive circuit 56 so that the rotation speed of the output shaft 32 becomes the rotation speed defined in the above-described speed map at the calculated position.

  A wiper switch 50 is connected to the microcomputer 58. The wiper switch 50 includes a low-speed operation mode selection position for rotating the wiper blades 28 and 30 at a low speed, a high-speed operation mode selection position for rotation at a high speed, an intermittent operation mode selection position for intermittent rotation at a constant period, Switching to the (stop) mode selection position is possible. Further, a signal corresponding to the selected position of each mode is output to the microcomputer 58. The microcomputer 58 performs control corresponding to the output signal from the wiper switch 50 according to the speed map stored in the memory 60.

  FIG. 2 is a diagram illustrating an example of the rotation angle sensor 54 according to the present embodiment. The rotation angle sensor 54 shown in FIG. 2 is a one-chip type sensor that can be mounted on the substrate 64, and is different from the end of the output shaft 32 in the speed reduction mechanism 52, that is, the end to which the crank arm 34 is attached. The magnetic field of the magnet 62 provided at the end is detected. The magnet 62 may be provided at the end where the crank arm 34 is attached. The magnet 62 may be provided on a member that rotates in conjunction with the output shaft 32 via a gear or the like.

  The rotation angle sensor 54 is provided to face the magnet 62, detects the magnetic field of the magnet 62, and outputs a voltage corresponding to the change of the magnetic field. For example, a Hall element or a magnetoresistive conversion (MR) element is used. It is what was used.

  FIG. 3 is a diagram illustrating an example of rotation of the magnet 62 on the rotation angle sensor 54 according to the present embodiment. 3 is a view of the magnet 62 and the rotation angle sensor 54 viewed from the direction of the arrow Z in FIG. 2, and the magnet 62 rotates 90 degrees in the direction of the arrow R from the state of FIG. A case where the state of B) is reached is shown. The magnet 62 shown in FIG. 3 has a cylindrical shape, and is provided with an S pole and an N pole at positions symmetrical to a plane passing through the center and perpendicular to the bottom surface. In the present embodiment, the magnet 62 has a shape other than a cylindrical shape, for example, a rod shape, a prism shape, or the like, as long as the S pole and the N pole are provided at positions symmetrical to a plane perpendicular to the bottom surface. An elliptic cylinder may be used.

  By rotating in the direction of the arrow R, the N-pole and S-pole magnetic fields of the magnet 62 also rotate, and the rotation angle sensor 54 outputs a voltage corresponding to the change in the magnetic field. FIG. 4 is a diagram illustrating an example of a change in the voltage value output from the rotation angle sensor 54 in the present embodiment. In FIG. 4, the voltage value output by the rotation angle sensor 54 when the magnet 62 rotates in the direction of the arrow R from the state of FIG.

  For example, if the rotation angle sensor 54 outputs 0 V in the state of FIG. 3A and the output voltage increases as the magnet 62 rotates in the direction of the arrow R, the rotation angle of the magnet 62 The relationship with the voltage output from the rotation angle sensor 54 is as shown in FIG. In the present embodiment, the rotation angle of the magnet 62, that is, the rotation angle of the output shaft is calculated from the voltage value output from the rotation angle sensor 54 based on the correspondence relationship between the rotation angle and the voltage value shown in FIG. Further, the rotation speed of the output shaft 32 is calculated from the rotation angles calculated based on the voltages detected at predetermined intervals.

  FIG. 5 is a diagram illustrating an example of voltage sampling in the present embodiment. In the present embodiment, the voltage output from the rotation angle sensor 54 is sampled at a predetermined time interval (sampling interval), and the rotation angle corresponding to the sampled voltage value is calculated.

  When calculating the rotation angle of the output shaft 32 by extracting the voltage value at a predetermined sampling interval from the change in voltage output from the rotation angle sensor 54, the rotation angle of the output shaft 32 can be reduced by shortening the predetermined sampling interval. Can be calculated more precisely.

  Furthermore, in the present embodiment, the difference between the rotation angle calculated based on the voltage sampled at a certain time and the rotation angle calculated based on the voltage sampled when a predetermined time has elapsed from the certain time is calculated as the predetermined angle. By dividing by time, the rotational speed of the output shaft 32 is calculated.

  For example, in the case of FIG. 5, the difference between the rotation angle β corresponding to the voltage value Vβ sampled at the time tβ when a predetermined time has elapsed from the time tα and the rotation angle α corresponding to the voltage value Vα sampled at the time tα is predetermined. The output shaft rotation speed is calculated by dividing by this time.

  The rotation speed to be calculated is an angular speed with the unit deg / s or rad / s, but the angular speed is divided by 360 when the rotation angle is in degrees and by 2π when the rotation angle is in radians. Thus, the rotation speed can be converted into rps or rpm.

  FIG. 6 is a flowchart showing an example of position / rotation speed detection processing in the wiper apparatus according to the present embodiment. In step 600, the counter N is reset, and in step 602, it is determined whether or not a predetermined sampling interval has elapsed since the counter N was reset in step 600. The predetermined sampling interval is 2 ms as an example, but can be changed as appropriate by rewriting the program of the microcomputer 58 or the like.

  If the determination in step 602 is affirmative, the voltage value, which is a signal from the rotation angle sensor 54, is sampled in step 604. In step 606, the rotation angle corresponding to the sampled voltage value is calculated and stored in the memory 60. To do. In step 608, the counter N is incremented by one. In step 610, it is determined whether or not the value of the counter N has reached a predetermined value M. The predetermined value is 10 as an example.

  If the determination in step 610 is affirmative, the rotational speed of the output shaft 32 is calculated in step 612 and the process returns. In step 610, based on the rotation angle calculated based on the voltage value sampled when the counter is N = M, that is, when the counter is N = M-1, and based on the voltage value sampled when the counter is N = 0. The rotational speed of the output shaft is calculated from the difference between the calculated rotation angles. The rotational speed of the output shaft 32 is calculated as an angular speed by dividing the difference between the rotational angles by a predetermined time. In the case of FIG. 6, the predetermined time is the product of the predetermined sampling time and M. When the predetermined sampling time is 2 msec and M = 10, the predetermined time is 20 msec. As described above, the angular velocity can be converted into a rotation speed in rpm units as necessary.

  In the case of negative determination in step 610, the procedure is returned to step 602. In step 602, it is determined whether or not a predetermined sampling time has elapsed from the setting of the counter in step 608. At 604, the signal is sampled again.

  FIG. 7 is a diagram showing an example of a speed map defining the rotational speed of the output shaft 32 of the wiper motor 18 in the present embodiment. In FIG. 7, the vertical axis represents the rotational speed of the output shaft 32, and the horizontal axis represents the positions of the wiper blades 28 and 30 on the front window 12. Further, the rotation angle of the output shaft 32 is shown in parentheses on the horizontal axis.

  In the present embodiment, the rotation speed corresponding to the rotation angle of the output shaft 32 calculated based on the detection result of the rotation angle sensor 54 is calculated from the speed map of FIG. Further, in the present embodiment, the rotation speed of the output shaft 32 is calculated from the rotation angle calculated based on the detection result of the rotation angle sensor 54, and the wiper motor is set so that the calculated rotation speed becomes the rotation speed calculated from the speed map. 18 rotations are controlled.

  As described above, according to the present embodiment, the rotation angle indicating the position of the wiper blades 28 and 30 and the rotation speed of the output shaft 32 can be detected from the detection result of the rotation angle sensor 54 as one sensor.

DESCRIPTION OF SYMBOLS 10 ... Wiper apparatus, 12 ... Front window, 14 ... Wiper, 18 ... Wiper motor, 20 ... Link mechanism, 22 ... Wiper control circuit, 24, 26 ... Wiper arm, 28 , 30 ... wiper blade, 32 ... output shaft, 34 ... crank arm, 36 ... link rod, 38, 40 ... pivot lever, 42, 44 ... pivot shaft, 46 ... Link rod 50 ... wiper switch 52 ... deceleration mechanism 54 ... rotation angle sensor 56 ... drive circuit 58 ... microcomputer 60 ... memory 62 ... Magnet, 64 ... substrate, P1 ... upper inversion position, P2 ... lower inversion position, P3 ... storage position

Claims (3)

A wiper blade that reciprocates and wipes the window glass surface;
A wiper motor connected to the output shaft via a link mechanism, and reciprocatingly rotating the wiper blade by rotation of the output shaft;
A magnet that rotates in conjunction with the rotation of the output shaft;
Detecting means for detecting the magnetic field of the magnet and outputting a change in the magnetic field of the magnet due to the rotation as a change in voltage;
The rotation angle of the output shaft indicating the position of the wiper blade on the window glass is calculated from a voltage value obtained by sampling the voltage output by the detection means at a predetermined sampling interval, and the calculation is performed at predetermined intervals. Control means for calculating the rotation speed of the output shaft from the rotation angle of the output shaft and the predetermined time, and controlling the rotation of the wiper motor based on the calculated rotation angle and rotation speed of the output shaft;
Wiper device with Storage means for storing a speed map defining the rotational speed of the output shaft in accordance with the rotational angle of the output shaft;
2. The wiper device according to claim 1, wherein the control unit controls the rotation of the wiper motor so that the calculated rotation speed of the output shaft becomes a rotation speed defined in the speed map.   3. The wiper device according to claim 1, wherein the control unit samples the voltage output from the detection unit by further shortening the predetermined sampling interval. 4.

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