Wiper control device

Abstract

To provide a wiper control device for estimating a rotation angle of a wiper with a simple configuration.SOLUTION: When an operation state of a wiper 90 is in a continuous high speed mode, an estimation part 64 of a wiper control device 30 acquires a voltage of a Lo terminal 106 that is a terminal different from a Hi terminal 104 to which a voltage is applied in a wiper motor 100. In the Lo terminal 106, when the voltage is applied to the Hi terminal 104, a noise voltage having periodicity is generated. Furthermore, at this time, the estimation part 64 estimates a wiper angle, on the basis of the voltage of the Lo terminal 106. When the operation state of the wiper 90 is in a continuous low speed mode, the estimation part 64 acquires a voltage of the Hi terminal 104 that is a terminal different from the Lo terminal 106 to which the voltage is applied in the wiper motor 100. The Hi terminal 104 generates a noise voltage. Furthermore, at this time, the estimation part 64 estimates the wiper angle, on the basis of the voltage of the Hi terminal 104.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a wiper control device.

Background Art

[0002] Conventionally, as described in Patent Document 1, there is known a wiper device that calculates the position of a wiper blade from a reference position based on the rotation speed of a rotor of a wiper motor detected by a hall sensor and the reduction ratio of a reduction mechanism of the wiper motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the wiper device described in Patent Document 1, a hall sensor for detecting the rotation speed of the rotor is provided. As a result, wiring for signals for the hall sensor is required, which complicates the configuration of the wiper device described in Patent Document 1. Therefore, the cost of the wiper device increases.

[0005] An object of the present disclosure is to provide a wiper control device that estimates the rotation angle of a wiper with a simple configuration.

Means for Solving the Problems

[0006] The invention described in claim 1 is a wiper device comprising: an acquisition unit (S200) that acquires the voltage of a second terminal (106, 104) of a wiper motor (100) that drives a wiper (90) that moves back and forth between a first position (Pd) and a second position (Pu), which is different from the first terminal (104, 106) to which a voltage is applied, and to which a periodic noise voltage (Vn) is generated when a voltage is applied to the first terminal; and an estimation unit (S210) that estimates the wiper angle (θw), which is the rotation angle of the wiper, based on the voltage of the second terminal when a voltage is applied to the first terminal.

[0007] This allows the wiper angle to be estimated without the need for a Hall sensor to detect the rotor's rotation speed. Therefore, there is no need to wire the signal for the Hall sensor. Consequently, the wiper angle can be estimated with a simple configuration.

[0008] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0009] [Figure 1] A diagram illustrating the configuration of a wiper drive system using a wiper control device according to one embodiment. [Figure 2] A diagram showing the wiper in a wiper drive system. [Figure 3] Diagram showing the relationship between noise voltage and time in a wiper motor of a wiper drive system. [Figure 4] A flowchart illustrating the processing of the drive unit of the wiper control device. [Figure 5] A flowchart illustrating the processing of the estimation unit of the wiper control device. [Figure 6] A diagram illustrating the relationship between the voltage applied to the wiper motor of a wiper drive system, the smoothed noise voltage, and time. [Figure 7] A diagram showing the configuration of a wiper drive system using a wiper control device of a modified embodiment. [Modes for carrying out the invention]

[0010] The embodiments will be described below with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numeral, and their descriptions will be omitted.

[0011] The wiper control device 30 of this embodiment is used in the wiper drive system 1 of a vehicle. First, this wiper drive system 1 will be described.

[0012] As shown in Figure 1, the wiper drive system 1 includes a motor unit 10, a motor ground 12, a motor power supply 14, a wiper switch 16, and a wiper control device 30.

[0013] The motor unit 10 has a wiper motor 100. The wiper motor 100 includes a Hi terminal 104, a Lo terminal 106, and a GND terminal 108. The Hi terminal 104 and Lo terminal 106 are connected to the wiper control device 30, which will be described later. The GND terminal 108 is connected to the motor ground 12. The wiper motor 100 rotates at a relatively high speed when power is supplied to the Hi terminal 104. The wiper motor 100 also rotates at a lower speed than when power is supplied to the Hi terminal 104 when power is supplied to the Lo terminal 106. The rotation of the wiper motor 100 and a linkage mechanism (not shown) connected to the wiper motor 100 operate the vehicle's wiper 90 as shown in Figure 2.

[0014] Furthermore, the rotation of the wiper motor 100 causes the wiper 90 to reciprocate between a lower inversion position Pd and an upper inversion position Pu on a windshield (not shown). At this time, as shown in Figure 3, the wiper motor 100 has the characteristic of generating a periodically fluctuating noise voltage Vn at terminals to which no voltage is applied. In addition, the noise voltage Vn momentarily increases when the commutator and brushes of the wiper motor 100 repeatedly make and remove contact while the wiper motor 100 is rotating. Also, when the wiper switch 16, described later, is turned off, the rotation of the wiper motor 100 stops so that the wiper 90 stops at the lower inversion position Pd.

[0015] Also, here, let the rotation angle of the wiper 90 when reciprocating between the lower inversion position Pd and the upper inversion position Pu be the wiper angle θw. Further, let the angle between the lower inversion position Pd and the upper inversion position Pu be the maximum angle θmax. The maximum angle θmax is, for example, 140 degrees. Also, here, the value of the wiper angle θw is in the range of zero or more and 2×θmax or less. Further, when the wiper angle θw is zero or 2×θmax, it is assumed that the wiper position Pw is at the lower inversion position Pd. Also, when the wiper angle θw is θmax, it is assumed that the wiper position Pw is at the upper inversion position Pu. Further, when 0 < θw < θmax, it is assumed that the wiper 90 is rotating from the lower inversion position Pd toward the upper inversion position Pu. Also, when θmax < θw < 2×θmax, it is assumed that the wiper 90 is rotating from the upper inversion position Pu toward the lower inversion position Pd.

[0016] Returning to FIG. 1, the motor power source 14 is a secondary battery such as a lithium ion battery, a nickel hydrogen battery, and a lead storage battery. Also, the voltage of the motor power source 14 is, for example, 12V.

[0017] The wiper switch 16 is operated by an operator and outputs a signal that causes the operating state of the wiper 90 to be in any one of a continuous high speed mode, a continuous low speed mode, an intermittent mode, and a stop, which will be described later, to the control unit 60 of the wiper control device 30 described later.

[0018] The wiper control device 30 controls the wiper motor 100 by controlling the voltage applied to the wiper motor 100. Thereby, the wiper control device 30 controls the driving of the wiper 90 connected to the wiper motor 100. Specifically, the wiper control device 30 includes a Hi switch 35, a Hi wiring 37, a Lo switch 45, a Lo wiring 47, and a control unit 60. <​The Hi switch 35 includes a relay, a transistor, or the like. One end of the Hi switch 35 is connected to the motor power supply 14. Further, the other end of the Hi switch 35 is connected to the Hi terminal 104 via the Hi wiring 37. The Hi switch 35 corresponds to a drive element and is turned on and off by a signal from the control unit 60 described later. Thereby, the energization to the Hi terminal 104 or the interruption of the current is performed.

[0020] The Lo switch 45 includes a relay, a transistor, or the like. One end of the Lo switch 45 is connected to the motor power supply 14. Further, the other end of the Lo switch 45 is connected to the Lo terminal 106 via the Lo wiring 47. The Lo switch 45 corresponds to a drive element and is turned on and off by a signal from the control unit 60 described later. Thereby, the energization to the Lo terminal 106 or the interruption of the current is performed.

[0021] The control unit 60 is mainly composed of a microcomputer or the like, and includes a CPU, a ROM, a flash memory, a RAM, an I / O, a drive circuit, an A / D converter, a comparator circuit, a DCDC converter, a low-pass filter, and a bus line connecting these components. The control unit 60 is driven by a voltage from the motor power supply 14 or a power supply not shown. Further, the control unit 60 has a motor temperature estimation unit 61, a drive unit 62, and an estimation unit 64 as functional blocks.

[0022] The motor temperature estimation unit 61 estimates the temperature of the wiper motor 100 by executing a program built into the control unit 60. For example, the motor temperature estimation unit 61 obtains the ambient temperature Te by communicating with a detection device (not shown). The motor temperature estimation unit 61 also obtains the motor current Im from a current detection unit (not shown) located in the Hi wiring 37 and Lo wiring 47. The detection device (not shown) uses a device such as a thermistor to detect the ambient temperature Te. Furthermore, the motor current Im is the current flowing through the wiper motor 100. The current detection unit (not shown) uses a device such as a shunt resistor, current mirror circuit, or Hall IC to detect the motor current Im.

[0023] Furthermore, the motor temperature estimation unit 61 calculates the power of the wiper motor 100 from the acquired motor current Im and the Hi voltage Vm_Hi or Lo voltage Vm_Lo. The motor temperature estimation unit 61 also estimates the temperature of the wiper motor 100 using the calculated power, the acquired ambient temperature Te, and the map. Furthermore, the motor temperature estimation unit 61 outputs a signal corresponding to the estimated wiper motor 100 to the estimation unit 64, which will be described later. The Hi voltage Vm_Hi is the voltage at the Hi terminal 104. The Lo voltage Vm_Lo is the voltage at the Lo terminal 106. Furthermore, when the ambient temperature Te is fixed, the amount of heat generated by the wiper motor 100 increases as the power increases. For this reason, the map for estimating the temperature of the wiper motor 100 is set such that, for example, the temperature of the wiper motor 100 increases as the power increases. Furthermore, when the power of the wiper motor 100 is fixed, the ambient temperature Te and the temperature of the wiper motor 100 are in equilibrium. For this reason, the map for estimating the temperature of the wiper motor 100 is set such that, for example, the temperature of the wiper motor 100 increases as the ambient temperature Te increases.

[0024] The drive unit 62 controls the on / off state of the Hi switch 35 and Lo switch 45 based on signals from the wiper switch 16 and the estimation unit 64 (described later) by executing a program built into the control unit 60. As a result, the drive unit 62 controls the voltage applied to the wiper motor 100. Therefore, the operating state of the wiper 90 can be one of the following: continuous high speed mode, continuous low speed mode, intermittent mode, or stopped.

[0025] The estimation unit 64 estimates the wiper angle θw based on the signal from the wiper switch 16, the temperature of the wiper motor 100, and the Hi voltage Vm_Hi and Lo voltage Vm_Lo, by executing a program built into the control unit 60. The estimation unit 64 also outputs a signal corresponding to the estimated wiper angle θw to the drive unit 62.

[0026] As described above, the wiper drive system 1 is configured. Next, the control of the voltage applied to the wiper motor 100 by the drive unit 62 through the execution of a program by the control unit 60 will be explained with reference to the flowchart in Figure 4. The program of the control unit 60 is executed, for example, when the ignition of a vehicle (not shown) is turned on.

[0027] In step S100, the drive unit 62 acquires various information. Specifically, the drive unit 62 acquires signals from the wiper switch 16 to set the operating state of the wiper 90 to continuous high speed mode, continuous low speed mode, and intermittent mode. The drive unit 62 also acquires the wiper angle θw from the estimation unit 64.

[0028] Next, in step S102, the drive unit 62 determines whether the wiper switch 16 is ON or OFF based on the signal from the wiper switch 16 acquired in step S100. When the drive unit 62 acquires a signal in step S100 to set the operating state of the wiper 90 to continuous high speed mode, continuous low speed mode, or intermittent mode, it determines that the wiper switch 16 is ON. After that, the drive unit 62 proceeds to step S104. Also, when the drive unit 62 acquires a signal in step S100 to stop the operating state of the wiper 90, it determines that the wiper switch 16 is OFF. At this point, the wiper 90 is stopped and there is no longer a need to drive the wiper 90, so the drive unit 62 returns to step S100.

[0029] In step S104, following step S102, the drive unit 62 determines whether the wiper angle θw obtained in step S100 is greater than or equal to θmax-Δ and less than θmax. Based on this, the drive unit 62 determines whether the wiper position Pw is immediately before the upper inversion position Pu. The drive unit 62 also determines whether the wiper angle θw obtained in step S100 is greater than or equal to 2×θmax-Δ and less than 2×θmax. Based on this, the drive unit 62 determines whether the wiper position Pw is immediately before the lower inversion position Pd. Note that Δ is set by experimentation or simulation, etc., so that it can be determined whether the wiper position Pw is immediately before the lower inversion position Pd or the upper inversion position Pu. For example, Δ is between 1 and 10 degrees.

[0030] Furthermore, when the wiper angle θw is less than θmax-Δ or equal to θmax, the wiper position Pw is not immediately before the upper inversion position Pu, so the drive unit 62 proceeds to step S106. Also, when the wiper angle θw is greater than θmax and less than 2×θmax-Δ, or equal to 2×θmax, the wiper position Pw is not immediately before the lower inversion position Pd, so the drive unit 62 proceeds to step S106. Moreover, when the wiper angle θw is greater than or equal to θmax-Δ and less than θmax, the wiper position Pw is immediately before the upper inversion position Pu, so the drive unit 62 proceeds to step S108. Also, when the wiper angle θw is greater than or equal to 2×θmax-Δ and less than 2×θmax, the wiper position Pw is immediately before the lower inversion position Pd, so the drive unit 62 proceeds to step S108.

[0031] In step S106, following step S104, the drive unit 62 turns on either the Hi switch 35 or the Lo switch 45. This causes the wiper motor 100 to rotate, thereby driving the wiper 90.

[0032] Here, for example, suppose the operator's action causes the wiper switch 16 to output a signal to the drive unit 62 that sets the wiper 90 to continuous high-speed mode. At this time, the drive unit 62 turns on the Hi switch 35. As a result, voltage is applied to the wiper motor 100 from the motor power supply 14 via the Hi switch 35, Hi wiring 37, and Hi terminal 104. This causes the wiper motor 100 to rotate at a higher speed than when power is supplied to the Lo terminal 106. Therefore, the wiper 90 connected to the wiper motor 100 rotates at high speed, setting the wiper 90 to continuous high-speed mode. Note that at this time, the Lo switch 45 is off.

[0033] For example, suppose the operator's action causes the wiper switch 16 to output a signal to the drive unit 62 that sets the wiper 90 to continuous low-speed mode. In this case, the drive unit 62 turns on the Lo switch 45. As a result, voltage is applied to the wiper motor 100 from the motor power supply 14 via the Lo switch 45, Lo wiring 47, and Lo terminal 106. This causes the wiper motor 100 to rotate at a lower speed than when power is supplied to the Hi terminal 104. Therefore, the wiper 90 connected to the wiper motor 100 rotates at a low speed, setting the wiper 90 to continuous low-speed mode. Note that the Hi switch 35 is off at this time. If the wiper 90 is in intermittent mode, the drive unit 62 turns on the Lo switch 45. This causes the wiper motor 100 to rotate at a low speed. Furthermore, when the wiper 90 is moving back and forth between the lower inversion position Pd and the upper inversion position Pu, and the wiper position Pw is at the lower inversion position Pd, the drive unit 62 turns off the Lo switch 45. As a result, the wiper motor 100 pauses, and the wiper 90 pauses as well. Subsequently, the drive unit 62 turns on the Lo switch 45. This causes the wiper motor 100 to rotate at a low speed. Therefore, these operations cause the wiper 90 to intermittently move back and forth between the lower inversion position Pd and the upper inversion position Pu.

[0034] After the drive unit 62 controls the Hi switch 35 and the Lo switch 45, the drive unit 62 returns to step S100.

[0035] In step S108, following step S104, the wiper position Pw is just before the down inversion position Pd or the up inversion position Pu. Therefore, in step S108, the drive unit 62 performs PWM control on the wiper motor 100 by controlling the on / off state of the Hi switch 35 or the Lo switch 45. As a result, the drive unit 62 reduces the power supplied to the wiper motor 100. This causes the wiper 90 to decelerate and move smoothly to the down inversion position Pd or the up inversion position Pu. Consequently, for example, the operating noise of the wiper 90 that occurs when the wiper position Pw is at the down inversion position Pd or the up inversion position Pu is reduced. PWM stands for Pulse Width Modulation.

[0036] Specifically, when the wiper 90 is operating in continuous high-speed mode, the drive unit 62 repeatedly turns the Hi switch 35 on for the first Hi period, and then off for the second Hi period. Similarly, when the wiper 90 is operating in continuous low-speed mode, the drive unit 62 repeatedly turns the Lo switch 45 on for the first Lo period, and then off for the second Lo period. These operations reduce the power supplied to the wiper motor 100, causing the wiper 90 to decelerate. As a result, the drive of the wiper 90 becomes smoother. When stopping the wiper 90, it smoothly stops at the lower inverted position Pd. The first Hi period, second Hi period, first Lo period, and second Lo period are set through experiments and simulations to reduce the power supplied to the wiper motor 100 and ensure smooth drive of the wiper 90. Furthermore, by gradually changing the power supplied to the wiper motor 100 through the first Hi time, second Hi time, first Lo time, and second Lo time settings, the operation of the wiper 90 becomes smoother.

[0037] In this manner, after the drive unit 62 controls the on / off state of either the Hi switch 35 or the Lo switch 45, the drive unit 62 returns to step S100.

[0038] As described above, the drive unit 62 controls the voltage applied to the wiper motor 100. Next, the estimation of the wiper angle θw by the estimation unit 64 through program execution by the control unit 60 will be explained with reference to the flowchart in Figure 5. The period of the series of operations from the start of processing in step S200 of the estimation unit 64 to the return to processing in step S200 is defined as the control period τ of the estimation unit 64.

[0039] In step S200, the estimation unit 64 acquires various information. Specifically, the estimation unit 64 acquires signals from the wiper switch 16 to set the operating state of the wiper 90 to continuous high speed mode, continuous low speed mode, intermittent mode, and stop. The estimation unit 64 also acquires the temperature of the wiper motor 100 from the motor temperature estimation unit 61. Furthermore, the estimation unit 64 acquires the Hi voltage Vm_Hi via the Hi wiring 37. The estimation unit 64 also acquires the Lo voltage Vm_Lo via the Lo wiring 47. Furthermore, the estimation unit 64 acquires the torque of the wiper motor 100 from a torque estimation device (not shown). The torque estimation device estimates the torque of the wiper motor 100 based on, for example, the state of the windshield (not shown), the vehicle speed, and the power of the wiper motor 100.

[0040] Here, for example, let's assume that the operating state of the wiper 90 is in continuous high-speed mode. In this case, the Hi switch 35 is turned on. As a result, voltage is applied to the wiper motor 100 from the motor power supply 14 via the Hi switch 35, Hi wiring 37, and Hi terminal 104. As a result, as shown in Figure 6, the Hi voltage Vm_Hi becomes a predetermined value. At this time, the Lo switch 45 is off, and due to the characteristics of the wiper motor 100, a noise voltage Vn is generated at the Lo terminal 106 to which no voltage is applied. Therefore, this noise voltage Vn corresponds to the Lo voltage Vm_Lo. Note that in Figure 6, the Hi voltage Vm_Hi and Lo voltage Vm_Lo are smoothed by being obtained through a low-pass filter or the like.

[0041] Furthermore, for example, suppose the operating state of the wiper 90 is in continuous low-speed mode or intermittent mode. In this case, the Lo switch 45 is turned on. As a result, voltage is applied to the wiper motor 100 from the motor power supply 14 via the Lo switch 45, Lo wiring 47, and Lo terminal 106. This causes the Lo voltage Vm_Lo to reach a predetermined value. At this time, the Hi switch 35 is off, and due to the characteristics of the wiper motor 100, a noise voltage Vn is generated at the Hi terminal 104 to which no voltage is applied. Therefore, this noise voltage Vn corresponds to the Hi voltage Vm_Hi.

[0042] Furthermore, as described above, the noise voltage Vn momentarily increases when the commutator and brushes of the wiper motor 100 repeatedly come into contact and not come into contact while the wiper motor 100 is rotating. In addition, the number of times the noise voltage Vn exceeds the noise threshold Vn_th while the wiper 90 is moving from the lower inversion position Pd to the upper inversion position Pu and from the upper inversion position Pu to the lower inversion position Pd is uniquely determined by the structure of the wiper motor 100. Therefore, by counting the number of times the noise voltage Vn exceeds the noise threshold Vn_th, or the number of times the noise voltage Vn goes from being greater than the noise threshold Vn_th to being less than or equal to the noise threshold Vn_th, as the number of pulses N, it is possible to estimate the wiper angle θw.

[0043] Furthermore, the noise voltage Vn changes as the voltage applied to the wiper motor 100 changes. In addition, the noise voltage Vn changes as the temperature of the wiper motor 100 changes. Also, the noise voltage Vn changes as the torque of the wiper motor 100 changes. Therefore, it is preferable to change the noise threshold Vn_th according to the voltage applied to the wiper motor 100, the temperature of the wiper motor 100, and the torque of the wiper motor 100.

[0044] Therefore, as shown in the flowchart of Figure 5, in step S202 following step S200, the estimation unit 64 calculates the noise threshold Vn_th. Specifically, the estimation unit 64 calculates the noise threshold Vn_th by using the temperature of the wiper motor 100 acquired in step S200, the Hi voltage Vm_Hi or Lo voltage Vm_Lo, the torque of the wiper motor 100, and the map.

[0045] For example, suppose the operating state of the wiper 90 is continuous high-speed mode. In this case, the estimation unit 64 calculates the noise threshold Vn_th using the temperature of the wiper motor 100, the Hi voltage Vm_Hi which is the voltage applied to the wiper motor 100, the torque of the wiper motor 100, and the map. Alternatively, suppose the operating state of the wiper 90 is continuous low-speed mode or intermittent mode. In this case, the estimation unit 64 calculates the noise threshold Vn_th using the temperature of the wiper motor 100, the Lo voltage Vm_Lo which is the voltage applied to the wiper motor 100, the torque of the wiper motor 100, and the map. The map for calculating the noise threshold Vn_th is set such that, for example, the noise threshold Vn_th increases as the temperature of the wiper motor 100 decreases. Furthermore, the map for calculating the noise threshold Vn_th is set such that, for example, the noise threshold Vn_th increases as the voltage applied to the wiper motor 100 increases. Furthermore, the map used to calculate the noise threshold Vn_th is set such that, for example, the noise threshold Vn_th increases as the torque of the wiper motor 100 increases.

[0046] Next, in step S204, the estimation unit 64 compares the noise voltage Vn, which corresponds to either the Hi voltage Vm_Hi or the Lo voltage Vm_Lo obtained in step S200, with the noise threshold Vn_th calculated in step S202.

[0047] For example, the estimation unit 64 determines whether the noise voltage Vn(n-1) in the previous control period τ(n-1) was less than the noise threshold Vn_th, and whether the noise voltage Vn(n) in the current control period τ(n) is greater than or equal to the noise threshold Vn_th. Based on this, the estimation unit 64 determines whether the noise voltage Vn is greater than or equal to the noise threshold Vn_th. Note that the noise voltage Vn(0) is, for example, zero. Alternatively, the estimation unit 64 may determine whether the noise voltage Vn(n-1) in the previous control period τ(n-1) is greater than the noise threshold Vn_th, and whether the noise voltage Vn(n) in the current control period τ(n) is less than or equal to the noise threshold Vn_th. Based on this, the estimation unit 64 may determine whether the noise voltage Vn was greater than or equal to the noise threshold Vn_th.

[0048] Furthermore, if the noise voltage Vn(n-1) in the previous control period τ(n-1) is less than the noise threshold Vn_th, and the noise voltage Vn(n) in the current control period τ(n) is greater than or equal to the noise threshold Vn_th, the estimation unit 64 proceeds to step S206. Also, if the noise voltage Vn(n-1) in the previous control period τ(n-1) is less than the noise threshold Vn_th, and the noise voltage Vn(n) in the current control period τ(n) is less than the noise threshold Vn_th, the estimation unit 64 proceeds to step S208. Moreover, if the noise voltage Vn(n-1) in the previous control period τ(n-1) is greater than or equal to the noise threshold Vn_th, and the noise voltage Vn(n) in the current control period τ(n) is greater than or equal to the noise threshold Vn_th, the estimation unit 64 proceeds to step S208. Furthermore, if the noise voltage Vn(n-1) in the previous control period τ(n-1) is greater than or equal to the noise threshold Vn_th, and the noise voltage Vn(n) in the current control period τ(n) is less than the noise threshold Vn_th, the estimation unit 64 proceeds to step S208.

[0049] In step S206, following step S204, the noise voltage Vn changes from less than the noise threshold Vn_th to greater than or equal to the noise threshold Vn_th. Therefore, at this point, the estimation unit 64 calculates the number of pulses N(n) in the current control period τ(n) by adding 1 to the number of pulses N(n-1) in the previous control period τ(n-1). Here, the number of pulses N is the number of times the noise voltage Vn changes from less than the noise threshold Vn_th to greater than or equal to the noise threshold Vn_th. Furthermore, the number of pulses N(0) is, for example, zero. Alternatively, the number of pulses N may be the number of times the noise voltage Vn changes from greater than the noise threshold Vn_th to less than or equal to the noise threshold Vn_th.

[0050] In step S208 following step S204, the noise voltage Vn does not rise to or exceed the noise threshold Vn_th from below the noise threshold Vn_th. Therefore, in this case, the estimation unit 64 sets the number of pulses N(n) in the current control period τ(n) to the number of pulses N(n-1) in the previous control period τ(n-1).

[0051] As described above, the rotation angle of the wiper motor 100 can be estimated from the number of times the noise voltage Vn exceeds the noise threshold Vn_th, i.e., the number of pulses N, and therefore the wiper angle θw can be estimated.

[0052] Therefore, in step S210, the estimation unit 64 estimates the wiper angle θw based on the number of pulses N(n) in the current control period τ(n) calculated above and the map. The estimation unit 64 also outputs a signal corresponding to the estimated wiper angle θw to the drive unit 62. After that, the processing of the estimation unit 64 returns to step S200. The map for estimating the wiper angle θw from the number of pulses N is set by the characteristics of the link mechanism and wiper motor 100 (not shown), experiments, simulations, etc. For example, suppose the number of pulses N when the wiper 90 moves back and forth between the lower inversion position Pd and the upper inversion position Pu is 1000. In this case, for example, when the number of pulses N(n) in the current control period τ(n) is 500, the wiper angle θw is estimated to be the maximum angle θmax, and the wiper position Pw is estimated to be the upper inversion position Pu. Furthermore, in this case, for example, if the number of pulses N(n) in the current control period τ(n) is 1000, the wiper angle θw is estimated to be 2 × θmax, and the wiper position Pw is estimated to be the downward inversion position Pd. Note that the number of pulses N may be reset at this time.

[0053] As described above, the estimation unit 64 estimates the wiper angle θw. Next, we will explain how the wiper control device 30 estimates the wiper angle θw with a simple configuration.

[0054] Assume that the wiper 90 is operating in continuous high-speed mode. In this case, in step S200, the estimation unit 64 acts as an acquisition unit to acquire the voltage of the Lo terminal 106, which is a terminal of the wiper motor 100 that is different from the Hi terminal 104 to which voltage is applied. When voltage is applied to the Hi terminal 104, a periodic noise voltage Vn is generated at the Lo terminal 106. Furthermore, in step S210, the estimation unit 64 estimates the wiper angle θw based on the voltage of the Lo terminal 106 acquired in step S200. The wiper motor 100 drives the wiper 90 to reciprocate between the lower inversion position Pd and the upper inversion position Pu. The lower inversion position Pd corresponds to the first position. Furthermore, the upper inversion position Pu corresponds to the second position. Furthermore, when the wiper 90 is operating in continuous high-speed mode, the Hi terminal 104 corresponds to the first terminal. Furthermore, when the wiper 90 is operating in continuous high-speed mode, the Lo terminal 106 corresponds to the second terminal.

[0055] Furthermore, the operating state of the wiper 90 is assumed to be either continuous low-speed mode or intermittent mode. In this case, the estimation unit 64 acts as an acquisition unit in step S200 to acquire the voltage of the Hi terminal 104, which is a terminal of the wiper motor 100 that is different from the Lo terminal 106 to which voltage is applied. At the Hi terminal 104, a periodic noise voltage Vn is generated when voltage is applied to the Lo terminal 106. Furthermore, in step S210, the estimation unit 64 estimates the wiper angle θw based on the voltage of the Hi terminal 104 acquired in step S200.

[0056] As a result, the wiper angle θw can be estimated without the need for a Hall sensor to detect the rotor's rotation speed. Therefore, there is no need to provide wiring for the Hall sensor signal. Consequently, the wiper angle θw can be estimated with a simple configuration. In addition, the wiper position Pw may be estimated by a cam switch that turns on and off in accordance with the rotation of the wiper motor 100. In contrast, the wiper control device 30 of this embodiment estimates the wiper position Pw by the above configuration, so it does not need to have a cam switch.

[0057] Furthermore, the wiper control device 30 of this embodiment also provides the following effects.

[0058] [1-1] The estimation unit 64 estimates the wiper angle θw based on the number of pulses N. This makes it easier to estimate the wiper angle θw. The number of pulses N corresponds to either the number of times the voltage at the second terminal changes from below the threshold to above the threshold, or the number of times the voltage at the second terminal changes from above the threshold to below the threshold.

[0059] [1-2] Here, the noise voltage Vn changes as the voltage applied to the wiper motor 100 changes. Also, the noise voltage Vn changes as the temperature of the wiper motor 100 changes. Furthermore, the noise voltage Vn changes as the torque of the wiper motor 100 changes.

[0060] In response to this, when the operating state of the wiper 90 is in continuous high-speed mode, the estimation unit 64 changes the noise threshold Vn_th in accordance with the change in the Hi voltage Vm_Hi in step S202. Also, when the operating state of the wiper 90 is in continuous low-speed mode or intermittent mode, the estimation unit 64 changes the noise threshold Vn_th in accordance with the change in the Lo voltage Vm_Lo in step S202. Furthermore, in step S202, the estimation unit 64 changes the noise threshold Vn_th in accordance with the change in the temperature of the wiper motor 100. Also, in step S202, the estimation unit 64 changes the noise threshold Vn_th in accordance with the change in the torque of the wiper motor 100.

[0061] These improvements enhance the accuracy of calculating the number of pulses N, which is determined by comparing the noise voltage Vn with the noise threshold Vn_th. Consequently, the accuracy of estimating the wiper angle θw improves.

[0062] [1-3] The drive unit 62 reduces the power supplied to the wiper motor 100 when either the wiper position Pw is immediately before the down inversion position Pd, or when the wiper position Pw is immediately before the up inversion position Pu.

[0063] This allows the wiper 90 to move smoothly to the lower inversion position Pd or the upper inversion position Pu. As a result, the operating noise of the wiper 90 that occurs when the wiper position Pw is the lower inversion position Pd or the upper inversion position Pu is reduced.

[0064] (modified version) In the above embodiment, the drive unit 62 controls the on / off state of the Hi switch 35 or Lo switch 45 in step S108. This reduces the power supplied to the wiper motor 100. However, the means by which the drive unit 62 reduces the power supplied to the wiper motor 100 is not limited to the on / off control described above. For example, the drive unit 62 may reduce the power supplied to the wiper motor 100 by controlling a DC-DC converter (not shown) connected to the motor power supply 14, thereby reducing the voltage applied from the motor power supply 14 to the wiper motor 100.

[0065] Furthermore, in the above embodiment, the estimation unit 64 may output a signal to an external device corresponding to the wiper angle θw estimated in step S210. For example, the external device is a washer device 70, as shown in Figure 7. The washer device 70 controls the timing of spraying washer fluid to clean the windshield (not shown) based on the signal from the estimation unit 64. For example, the washer device 70 sprays washer fluid when the wiper angle θw estimated by the estimation unit 64 is zero or 2 × θmax, that is, when the wiper position Pw is in the downward inverted position Pd.

[0066] (Other embodiments) This disclosure is not limited to the embodiments described above, and modifications can be made to these embodiments as appropriate. Furthermore, it goes without saying that, in each of the embodiments described above, the elements constituting the embodiment are not necessarily essential, except in cases where they are explicitly stated to be particularly essential or where they are clearly considered essential in principle.

[0067] The acquisition unit, estimation unit, drive unit and method described in this disclosure may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the acquisition unit, estimation unit, drive unit and method described in this disclosure may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the acquisition unit, estimation unit, drive unit and method described in this disclosure may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0068] (Perspective of this disclosure) [Perspective 1] An acquisition unit (S200) acquires the voltage of a second terminal (106, 104) which is different from the first terminal (104, 106) to which voltage is applied, among the wiper motor (100) that drives a wiper (90) that moves back and forth between a first position (Pd) and a second position (Pu), and which generates a periodic noise voltage (Vn) when a voltage is applied to the first terminal. When a voltage is applied to the first terminal, an estimation unit (S210) estimates the wiper angle (θw), which is the rotation angle of the wiper, based on the voltage of the second terminal, A wiper control device equipped with the following features. [Perspective 2] The wiper control device according to viewpoint 1, wherein the estimation unit estimates the wiper angle based on the number of times (N) when the voltage of the second terminal changes from less than a threshold (Vn_th) to greater than or equal to the threshold. [Perspective 3] The wiper control device according to viewpoint 1, wherein the estimation unit estimates the wiper angle based on the number of times (N) when the voltage of the second terminal goes from being greater than a threshold (Vn_th) to being less than or equal to the threshold. [Perspective 4] The wiper control device according to viewpoint 2 or 3, wherein the estimation unit changes the threshold in accordance with the change in the voltage of the first terminal. [Perspective 5] The wiper control device according to any one of viewpoints 2 to 4, wherein the estimation unit changes the threshold in accordance with the temperature change of the wiper motor. [Perspective 6] The wiper control device according to any one of viewpoints 2 to 5, wherein the estimation unit changes the threshold in accordance with the change in the torque of the wiper motor. [perspective 7] A wiper control device according to any one of views 1 to 6, further comprising a drive unit (62) that reduces the power supplied to the first terminal when the wiper is in a position immediately before the first position, or when the wiper is in a position immediately before the second position. [Perspective 8] The wiper control device further includes drive elements (35, 45) that, when turned on, apply a voltage to the first terminal to rotate the wiper motor. The wiper control device according to viewpoint 7, wherein the drive unit reduces the power supplied to the first terminal by turning the drive element on and off when the wiper is in either the position immediately before the first position or the position immediately before the second position. [Explanation of Symbols]

[0069] 14 Motor power supply 16 Wiper switch 35 Hi-Switch 45 Lo switch 60 Control Unit 61 Motor temperature estimation unit 62 Drive unit 64 Estimation part 100 wiper motors

Claims

1. An acquisition unit (S200) acquires the voltage of a second terminal (106, 104) of a wiper motor (100) that drives a wiper (90) that moves back and forth between a first position (Pd) and a second position (Pu), which is different from the first terminal (104, 106) to which a voltage is applied, and which generates a periodic noise voltage (Vn) when a voltage is applied to the first terminal. When a voltage is applied to the first terminal, an estimation unit (S210) estimates the wiper angle (θw), which is the rotation angle of the wiper, based on the voltage of the second terminal, A wiper control device equipped with the following features.

2. The wiper control device according to claim 1, wherein the estimation unit estimates the wiper angle based on the number of times (N) when the voltage of the second terminal changes from less than a threshold (Vn_th) to greater than or equal to the threshold.

3. The wiper control device according to claim 1, wherein the estimation unit estimates the wiper angle based on the number of times (N) when the voltage of the second terminal goes from being greater than a threshold (Vn_th) to being less than or equal to the threshold.

4. The wiper control device according to claim 2 or 3, wherein the estimation unit changes the threshold value in accordance with the change in the voltage of the first terminal.

5. The wiper control device according to claim 2 or 3, wherein the estimation unit changes the threshold value in accordance with the temperature change of the wiper motor.

6. The wiper control device according to claim 2 or 3, wherein the estimation unit changes the threshold value in accordance with the change in torque of the wiper motor.

7. The wiper control device according to any one of claims 1 to 3, further comprising a drive unit (62) that reduces the power supplied to the first terminal when the wiper is in a position immediately before the first position, or when the wiper is in a position immediately before the second position.

8. The wiper control device further includes drive elements (35, 45) that, when turned on, apply a voltage to the first terminal to rotate the wiper motor. The wiper control device according to claim 7, wherein the drive unit reduces the power supplied to the first terminal by turning the drive element on and off when the wiper is in either the position immediately before the first position or the position immediately before the second position.

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