JP2011046358A - Heater controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heater controller capable of preventing excessive electric power from being consumed in a heater load such as a wiper de-icer after a freeze completely has melted away. <P>SOLUTION: The electric current value when a flow of electricity is applied to a heater resistance 2 is detected by an ampere-meter 6, and a voltage value is detected by a voltmeter 7. The heater controller 1 obtains a resistance value from the current value and the voltage value of the heater resistance 2 so as to calculate the variation rate of the resistance value. When the variation rate of the resistance value of the heater resistance 2 is smaller than the threshold value in variation rate and the resistance value of the heater resistance 2 is larger than the threshold value of the first resistance, the reduction in the flow amount of electricity or stoppage of electricity feeding to the heater resistance 2 is carried out. Further, when the resistance value of the heater resistance 2 surpasses the threshold value of the second resistance, the reduction in the flow amount of electricity or stoppage of electricity feeding to the heater resistance 2 is carried out. When the outside air surpasses the predetermined temperature detected by an outside temperature sensor 5, feeding of electricity to the heater resistance 2 is stopped and when the outside air does not exceed the predetermined temperature, the flow amount of electricity to the heater resistance 2 is reduced without stopping feeding of electricity to the heater resistance 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heater control device that prevents energization of devices such as a window glass and a wiper provided around the window glass by controlling energization of a heater such as a heat wire provided on a window glass of a vehicle.

  In recent years, in order to improve vehicle safety, convenience, comfort, product power, etc., the number of electric components mounted on vehicles has been increasing, and the amount of electric power consumed by vehicles has increased with the increase in electric components. Has increased. There is a need to improve the fuel efficiency of vehicles for environmental measures and the like, but there is a problem that an increase in the amount of electric power consumed by in-vehicle electrical components causes a deterioration in fuel efficiency. In particular, in the case of a hybrid vehicle, an electric vehicle, or the like, an increase in the amount of power consumption of the electrical components directly affects the travelable distance (fuel consumption) of the vehicle. Therefore, it is required to reduce the power consumption of the on-vehicle electrical components.

  On the other hand, there is a vehicle equipped with a wiper deicer that melts freezing of the wiper and the front window by a heat ray provided on the front window. The wiper deicer is an electrical component that is often installed in vehicles used especially in cold regions, etc., and it is said that melting the freeze by heating the hot wire etc. provided on the front window etc. according to the driver's switch operation Is. If the driver forgets to stop the operation of the wiper deicer after the wiper deicer is sufficiently frozen by the wiper deicer, extra power is consumed by the wiper deicer. For this reason, for example, a function such as a timer that automatically determines that a certain amount of time has passed and automatically stops the wiper deicer is provided. However, the wiper and the front window are frozen before the certain amount of time has elapsed. If it melts sufficiently, there is a problem that extra power is consumed.

  In Patent Document 1, a wiper motor that drives a wiper according to an operation signal from a wiper switch, a wiper deicer such as a heat ray disposed on a glass surface of a vehicle window, an outside air temperature sensor that detects outside air temperature, And a current detecting means for detecting a lock current flowing in the wiper motor, and when the frozen state is detected by the outside air temperature data detected by the outside air temperature sensor and the lock current is detected by the current detecting means, the wiper deicer A wiper de-icer device has been proposed in which the wiper is automatically operated for a predetermined time to automatically prevent freezing of the wiper and prevent burning due to a lock current.

JP 2003-154924 A

  However, the wiper deicer device described in Patent Document 1 is configured to operate the wiper deicer for a predetermined time when a frozen state and a lock current are detected, and the wiper deicer that has automatically started operation stops operating. Is after a predetermined time has elapsed. Therefore, this wiper deicer device cannot solve the problem that excessive power is consumed when the freezing is sufficiently melted before the predetermined time has elapsed.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a heater control device that can prevent excessive electric power from being consumed after freezing has sufficiently melted. There is to do.

  The heater control device according to the present invention is a heater control device that controls energization of a heater load provided in a vehicle, a resistance value acquisition unit that acquires the resistance value of the heater load in time series, and the resistance value acquisition A calculating means for calculating a change rate of the resistance value acquired by the means; and an energization control means for performing control for adjusting an energization amount to the heater load according to the change rate calculated by the calculating means. And

  Further, the heater control device according to the present invention includes a change rate determination unit that determines whether or not the change rate calculated by the calculation unit is smaller than a change rate threshold value, and the resistance value acquired by the acquisition unit is a resistance threshold value. Resistance value determining means for determining whether or not the change rate is greater than the resistance value determining means, wherein the energization control means is determined by the change rate determining means that the change rate is smaller than the change rate threshold, and the resistance value determining means. When the resistance value is determined to be greater than the resistance threshold value, the amount of power supplied to the heater load is reduced.

  The heater control device according to the present invention further includes an upper limit determination unit that determines whether or not the resistance value acquired by the acquisition unit exceeds an upper limit value, and the energization control unit is configured by the upper limit determination unit. When it is determined that the resistance value exceeds the upper limit value, the energization amount to the heater load is reduced.

  Moreover, the heater control apparatus according to the present invention is characterized in that the energization control means stops energization to the heater load.

  In addition, the heater control device according to the present invention further includes an outside air temperature detection unit that detects an outside air temperature of the vehicle, and the energization control unit is provided when the outside air temperature detected by the outside air temperature detection unit is lower than a predetermined temperature. The amount of energization to the heater load is reduced, and the energization to the heater load is stopped when the outside air temperature detected by the outside air temperature detecting means is higher than a predetermined temperature.

  The heater control device according to the present invention is characterized in that the heater load is a heat ray provided on a window glass of the vehicle.

In the present invention, the heater control device measures the current and voltage when the heater load such as the wiper deicer is energized, thereby acquiring the resistance value of the heater load in time series and the acquired heater Calculate the rate of change in load resistance.
The heater load such as a hot wire has a lower resistance value as the temperature is lower, and a higher resistance value as the temperature is higher. Further, when the temperature of the heater load increases due to energization, the resistance value of the heater load also increases accordingly. From these facts, it is possible to estimate the heater load and its surrounding temperature based on the rate of change of the resistance value of the heater load, and to estimate whether or not the heater load and its surrounding are in a frozen state. Is possible. Therefore, the heater control device can prevent excessive power consumption by the heater load after the frozen state is eliminated by adjusting the energization amount to the heater load according to the change rate of the resistance value of the heater load.

When energization is started with respect to the frozen heater load, the temperature of the heater load gradually rises to approximately 0 ° C., and the frozen state starts to be eliminated. Thereafter, the heater load is maintained at approximately 0 ° C., the frozen state is eliminated, and after the frozen state is completely eliminated, the temperature of the heater load increases with energization. Focusing on the resistance value of the heater load at this time, the resistance value rises in a period from the start of energization to approximately 0 ° C., and the resistance value is kept constant for a while after reaching approximately 0 ° C., The resistance value rises after the temperature rise of the heater load is resumed. The resistance value of the heater load at approximately 0 ° C. can be estimated in advance from the characteristics of the heater load.
Therefore, in the present invention, when the rate of change of the resistance value of the heater load is smaller than the predetermined rate of change threshold and the resistance value of the heater load exceeds the predetermined resistance threshold, it is determined that the frozen state has been eliminated. By reducing the energization amount to the heater load, excessive power consumption is prevented.

However, when the degree of freezing is low or not frozen, the temperature of the heater load does not become substantially constant with energization and may continue to increase. Therefore, when the resistance value of the heater load at a temperature sufficiently higher than 0 ° C. is set in advance as an upper limit value and the resistance value of the heater load exceeds the upper limit value, regardless of the rate of change of the resistance value of the heater load. Reduce the amount of electricity to the heater load.
Therefore, in the present invention, the temperature of the heater load can be prevented from continuing to increase even when the heater load is energized when the degree of freezing is low or when it is not frozen.

  In the present invention, energization to the heater load is stopped when the frozen state is eliminated. Thereby, the power consumption by a heater load can be stopped completely and the extra power consumption after a frozen state cancellation can be prevented reliably.

  When the temperature of the heater load reaches approximately 0 ° C. and the frozen state is eliminated, there is a risk that refreezing will occur if the outside air temperature is low. Therefore, in the present invention, when the heater control device detects the outside air temperature and the frozen state is eliminated, if the outside air temperature is higher than the predetermined temperature, the energization to the heater load is stopped, but the frozen state is eliminated. If the outside air temperature is lower than the predetermined temperature, the energization to the heater load is not stopped but the energization amount to the heater load is only reduced. Thereby, the power consumption can be reduced after the frozen state is eliminated, and refreezing when the outside air temperature is low can be prevented.

  In the present invention, the heater load controlled by the heater control device is a heat ray provided on the window glass of the vehicle. This is a heater load such as a wiper deicer, and it may be difficult to determine whether the frozen state has been eliminated by using a thermometer or the like. It is preferable to determine whether the frozen state is eliminated based on the rate of change in resistance value.

  In the case of the present invention, by obtaining the resistance value of the heater load, calculating the change amount of the resistance value, and controlling the energization amount to the heater load according to the calculated change amount, It is possible to estimate whether or not the surrounding area is in a frozen state, and to reduce the energization amount to the heater load after the frozen state is eliminated. Therefore, it is possible to prevent excessive electric power from being consumed by the heater load after the freezing state is eliminated, thereby contributing to an improvement in the fuel consumption of the vehicle.

It is a block diagram which shows the structure of the heater control apparatus which concerns on this invention. It is a schematic diagram for demonstrating the change of the resistance value at the time of energizing heater resistance. It is a flowchart which shows the procedure of the energization control process of the heater resistance which the heater control apparatus which concerns on this invention performs. It is a flowchart which shows the procedure of the freeze elimination determination process which the heater control apparatus which concerns on this invention performs.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof. FIG. 1 is a block diagram showing a configuration of a heater control device according to the present invention. In the figure, reference numeral 1 denotes a heater control device that controls energization to a heater resistance (heater load) 2 mounted on a vehicle. The heater control device 1 controls, for example, a control for switching supply / non-supply of power from a power source such as an alternator and a battery to a heater resistor 2 of a wiper deicer provided on a windshield (not shown) of a vehicle. Control to switch energization / non-energization of the heater resistor 2 is performed.

  The heater control device 1 includes a switching element 12 arranged in a current path from a power source (indicated as + B in the drawing) to the heater resistor 2, and a control unit that outputs a control signal for switching on / off the switching element 12. 11. Specifically, the control unit 11 includes an arithmetic processing device such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) and a storage element such as a ROM (Read Only Memory) or a RAM (Random Access Memory). By executing a program that is configured and stored in advance, a process for generating and outputting a control signal related to the control of the heater resistor 2 is performed.

  The control unit 11 also includes an on / off state of a de-icer switch 3 that accepts an operation related to turning on / off of the wiper de-icer by a driver, an on / off state of an ignition (hereinafter referred to as IG) switch 4 of the vehicle, The detection result of the outside temperature sensor 5 that detects the temperature, the detection result of the ammeter 6 that detects the current flowing through the heater resistor 2, the detection result of the voltmeter 7 that detects the voltage applied to the heater resistor 2, and the like are input. Yes.

  The deaiser switch 3 is disposed in the vicinity of the driver's seat of the vehicle (for example, an instrument panel or the like), and accepts an on / off switching operation by the driver. The on / off state of the de-icer switch 3 is notified to the control unit 11 of the heater control device 1. The heater control device 1 energizes the heater resistor 2 when the de-icer switch 3 is on, and the de-icer switch 3 is off. In the state, the heater resistor 2 is not energized.

  The IG switch 4 is disposed in the vicinity of the driver's seat of the vehicle, and accepts operations such as starting the engine of the vehicle by the driver. For example, the IG switch 4 may be configured such that the driver inserts a vehicle key to perform a turning operation, and the turning position is notified to the control unit 11 of the heater control device 1. The rotation position of the IG switch 4 is, for example, a start position for starting the engine, a position where the engine can be kept running while the engine is running, and the engine is stopped and the vehicle is connected to an in-vehicle device such as an audio device. The accessory position to which the electric power is supplied, the stop position where the engine is stopped and the power supply to the in-vehicle device is also stopped, and the IG switch 4 is rotated to the stop position in the present embodiment. Is referred to as an off state, and a state in which a rotation operation is performed at other positions is referred to as an on state. The IG switch 4 is not limited to a rotary operation, and may have other configurations such as a push switch.

  The ammeter 6 is connected in series between, for example, the switching element 12 and the heater resistor 2, and the amount of current flowing through the current path from the switching element 12 to the heater resistor 2 is time-sequentially (that is, periodically). Detect repeatedly) The voltmeter 7 is connected in parallel to the heater resistor 2 and detects the voltage applied to both ends of the heater resistor 2 in time series. The current detected by the ammeter 6 and the voltage detected by the voltmeter 7 are given to the control unit 11 of the heater control device 1, whereby the control unit 11 can obtain the resistance value of the heater resistor 2 in time series. In this embodiment, the ammeter 6 and the voltmeter 7 are used to obtain the resistance value of the heater resistor 2, but the present invention is not limited to this, and the resistance value of the heater resistor 2 is obtained by other methods. It may be configured to.

  The heater resistor 2 is, for example, a heat ray disposed in the lower part of the windshield of the vehicle and in the vicinity of the wiper stop position. One end of the heater resistor 2 is connected to the switching element 12 of the heater control device 1 via the ammeter 6, and the other end is connected to the ground potential. When the heater control device 1 energizes the heater resistor 2, the temperature of the heater resistor 2 rises and the freezing of the windshield and the wiper can be eliminated.

  The switching element 12 is realized using, for example, an FET (Field Effect Transistor). In this case, the switching element 12 has a source terminal connected to the power supply, a drain terminal connected to the heater resistor 2 via the ammeter 6, a gate terminal connected to the control unit 11, and a control signal input. Thereby, the switching element 12 can switch supply / non-supply of power from the power source to the heater resistor 2 according to the signal level of the control signal. Note that the switching element 12 is not limited to an FET, and an element such as a bipolar transistor or a relay may be used.

  FIG. 2 is a schematic diagram for explaining a change in the resistance value when the heater resistor 2 is energized. The horizontal axis is the elapsed time from the start of energization, and the vertical axis is the resistance value of the heater resistor 2. It is a graph. In the case where the windshield and the wiper are in a frozen state, when the energization of the heater resistor 2 is started (time t0), the temperature of the heater resistor 2 gradually increases. Since the resistance value of the heater resistor 2 is smaller as the temperature is lower, the resistance value of the heater resistor 2 gradually increases as the temperature rises (time t0 to time t1).

  Thereafter, the freezing of the windshield and the wiper starts to melt as the temperature of the heater resistor 2 rises. This timing is time t1 in the figure, and the temperature of the heater resistor 2 at this time is approximately 0 ° C. From the start of freezing until the freezing is eliminated (time t1 to time t2), the heater resistance 2 does not change in temperature and becomes substantially constant (or the time t1 from the rate of temperature increase from time t0 to time t1). The temperature increase rate at time t2 is small). When the temperature is substantially constant, the resistance value of the heater resistor 2 is substantially constant. After the freezing is eliminated, the heater resistor 2 gradually increases in temperature with energization, and the resistance value gradually increases (after time t2).

  As described above, the resistance value of the heater resistor 2 first increases with the start of energization, becomes substantially constant at the start of freezing, and increases again after the freezing is released. The heater control device 1 of the present invention can acquire the resistance value of the heater resistor 2 from the current detected by the ammeter 6 and the voltage detected by the voltmeter 7, and by examining the change in the resistance value of the heater resistor 2. Then, the timing of the start of freezing (timing at time t1) is detected, and at this timing, the energization amount to the heater resistor 2 is reduced or the energization is stopped.

  Specifically, the heater control device 1 calculates the rate of change of the resistance value of the heater resistor 2 and determines whether or not the rate of change is smaller than a predetermined rate of change threshold. It is determined whether or not the resistance value is substantially constant. The change rate threshold for comparison with the change rate is determined in advance by the designer of the heater control device 1 in accordance with the characteristics of the heater resistor 2, the voltage applied to the heater resistor 2, and the like. When it is determined that the rate of change of the resistance value of the heater resistor 2 is smaller than the rate of change threshold, the heater control device 1 can determine that it is the timing at which the freezing starts.

  Furthermore, the temperature of the heater resistor 2 is substantially constant around 0 ° C. (about 0 ° C. ± several degrees C.), and the resistance value of the heater resistor 2 at 0 ° C. can be acquired in advance. In consideration of variations in the characteristics of the heater resistance 2 and variations in temperature, etc., a value lower than the resistance value at 0 ° C. (for example, the resistance value of the heater resistance 2 at −5 ° C.) is set in advance as the first resistance threshold value. deep. The heater control device 1 is one in which freezing is eliminated when the resistance value of the heater resistor 2 exceeds the first resistance threshold value and the rate of change of the resistance value of the heater resistor 2 is smaller than the rate of change threshold value as described above. It is judged that the energization amount to the heater resistor 2 is reduced or energization is stopped.

  Further, when the degree of freezing is low or not frozen, there is a possibility that the temperature of the heater resistor 2 does not become substantially constant with energization and continues to increase. Therefore, the resistance value of the heater resistor 2 at a temperature sufficiently higher than 0 ° C. (for example, 15 ° C. or the like) is set in advance as a second resistance threshold value (upper limit value) (note that the second resistance threshold value> the first resistance threshold value). . When the resistance value of the heater resistance 2 exceeds the second resistance threshold value, the heater control device 1 determines that the freezing has been resolved regardless of the rate of change of the resistance value of the heater resistance 2, and then proceeds to the heater resistance 2. Reduce the energization amount or stop energization.

  Further, the heater control device 1 determines whether or not the outside air temperature detected by the outside air temperature sensor 5 exceeds a predetermined temperature (for example, 0 ° C.) when it is determined that the freezing has been eliminated. Even when freezing is eliminated, there is a risk of refreezing if the outside air temperature is low. For this reason, the heater control device 1 determines that the resistance value of the heater resistor 2 exceeds the first resistance threshold value and the rate of change of the resistance value of the heater resistor 2 is smaller than the rate of change threshold value, or the resistance value of the heater resistor 2 is the first value. If the outside temperature exceeds a predetermined temperature when the 2 resistance threshold is exceeded, energization to the heater resistor 2 is stopped, but if the outside air temperature does not exceed the predetermined temperature, the energization to the heater resistor 2 is not stopped. Reduce energization (power saving energization).

  For example, if the controller 11 is configured to control the switching element 12 by PWM (Pulse Width Modulation), the amount of energization to the heater resistor 2 can be adjusted by adjusting the duty ratio of the control signal to be output. . For example, the control unit 11 may output an analog value control signal to adjust the energization amount of the switching element 12.

  The heater control device 1 includes a timer (not shown in FIG. 1) in the control unit 11 and the like, and measures the elapsed time from the start of energization of the heater resistor 2. When sufficient time (for example, 30 minutes or 1 hour) has passed since the start of energization, freezing is considered to have been sufficiently eliminated. Therefore, the heater control device 1 stops energization to the heater resistor 2 when the time measured by the timer has passed a predetermined time.

  FIG. 3 is a flowchart showing a procedure of the energization control process of the heater resistor 2 performed by the heater control device 1 according to the present invention, and is a process performed by the control unit 11 of the heater control device 1. First, the control unit 11 of the heater control device 1 determines whether or not the IG switch 4 of the vehicle is on (step S1). If the IG switch 4 is not on (S1: NO), the heater resistance 2 is stopped (step S9), and the process is terminated. When the IG switch 4 is on (S1: YES), the control unit 11 further determines whether or not the de-icer switch 3 is on (step S2). When the de-icer switch 3 is not in the ON state (S2: NO), the control unit 11 stops energizing the heater resistor 2 (step S9) and ends the process.

  When the de-icer switch 3 is in the on state (S2: YES), the control unit 11 determines whether or not the time measured by the timer has passed a predetermined time (step S3). In addition, although illustration is abbreviate | omitted in the flowchart of FIG. 3, when the energization to the heater resistance 2 is started, the control unit 11 starts the time measurement by the timer, and when the energization to the heater resistance 2 is stopped, Is stopped and the timer is reset. When the time measured by the timer has passed the predetermined time (S3: YES), the control unit 11 stops energizing the heater resistor 2 (step S9) and ends the process. When the time measured by the timer has not passed the predetermined time (S3: NO), the control unit 11 performs a freeze elimination determination process for determining whether or not freezing of the windshield and the wiper of the vehicle has been eliminated (step S4). ).

  FIG. 4 is a flowchart showing the procedure of the freeze elimination determination process performed by the heater control apparatus 1 according to the present invention, and is the process performed by the control unit 11 in step S4 of the flowchart shown in FIG. In the freeze elimination determination process, the controller 11 of the heater control device 1 detects the current by the ammeter 6 and the voltage by the voltmeter 7 (step S21), and determines the resistance of the heater resistor 2 from the detected current and voltage. A value is acquired (step S22). The control unit 11 stores the previously acquired resistance value of the heater resistance 2, and compares the newly acquired resistance value with the previously stored resistance value, thereby changing the rate of change of the resistance value of the heater resistance 2. Is calculated (step S23).

  Next, the controller 11 determines whether or not the resistance value of the heater resistor 2 exceeds a predetermined second resistance threshold value (step S24), and when the resistance value of the heater resistor 2 exceeds the second resistance threshold value (step S24). (S24: YES), it is determined that the freezing has been eliminated (step S27), and the freeze elimination determination process is terminated.

  When the resistance value of the heater resistor 2 does not exceed the second resistance threshold value (S24: NO), the control unit 11 determines whether or not the change rate of the resistance value of the heater resistor 2 is smaller than a predetermined change rate threshold value. (Step S25). When the change rate of the resistance value is smaller than the change rate threshold value (S25: YES), the control unit 11 further determines whether or not the resistance value of the heater resistor 2 exceeds the first resistance threshold value (step S26).

  When the change rate of the resistance value of the heater resistor 2 is smaller than the change rate threshold value and the resistance value of the heater resistor 2 exceeds the first resistance threshold value (S26: YES), the control unit 11 determines that the freezing has been eliminated. (Step S27), and the freeze elimination determination process is terminated. When the change rate of the resistance value of the heater resistor 2 is larger than the change rate threshold value (S25: NO), or when the resistance value of the heater resistor 2 does not exceed the first resistance threshold value (S26: NO), the control unit 11 It is determined that the freezing has not been solved (step S28), and the freezing elimination determination process is terminated.

  After completing the freezing elimination determination process in step S4, the control unit 11 checks whether the freezing has been eliminated from the determination result (step S5). If the freezing has not been eliminated (S5: NO), the heater resistance 2 is normally energized (step S7), and the process is terminated. When the freezing is eliminated (S5: YES), the control unit 11 determines whether or not the outside air temperature detected by the outside air temperature sensor 5 exceeds a predetermined temperature (step S6). When the outside air temperature does not exceed the predetermined temperature (S6: NO), the control unit 11 performs power saving energization to reduce the energization amount to the heater resistor 2 (step S8), and the outside air temperature reaches the predetermined temperature. When exceeding (S6: YES), electricity supply to the heater resistance 2 is stopped (step S9), and a process is complete | finished. In addition, the control part 11 is performing the process of above-mentioned step S1-S9 repeatedly.

  In the heater control device 1 configured as described above, the resistance value of the heater resistor 2 is obtained from the current and voltage when the heater resistor 2 such as a wiper deicer is energized, and the rate of change of the resistance value is further calculated. Based on the rate of change of the resistance value of the heater resistor 2, the heater resistor 2 and the surrounding temperature can be estimated, and it can be determined whether or not the freezing has been eliminated. The heater control device 1 determines that the freezing has been eliminated when the rate of change of the resistance value of the heater resistor 2 is smaller than the rate of change threshold, that is, when the resistance value is kept substantially constant, and the heater resistance 2 By adopting a configuration in which the amount of energization is reduced or the energization is stopped, excessive power consumption after freezing can be prevented.

  The heater control device 1 also eliminates freezing when the rate of change of the resistance value of the heater resistor 2 is smaller than a predetermined rate of change threshold value and the resistance value of the heater resistor 2 is greater than a predetermined first resistance threshold value. The heater control device 1 is frozen only from information on the current and voltage detected by the ammeter 6 and the voltmeter 7 by reducing the energization amount to the heater resistor 2 or stopping the energization. Resolution can be determined with high accuracy. Therefore, the heater control device 1 does not need to be provided with a new and expensive device for determining freezing, so that excessive power consumption by the heater resistor 2 can be prevented without causing a significant increase in cost. Can be realized.

  Further, the heater control device 1 determines whether or not the resistance value of the heater resistor 2 exceeds a predetermined second resistance threshold value, and when the resistance value exceeds the second resistance threshold value, the amount of energization to the heater resistor 2 is determined. By adopting a configuration that reduces or stops energization, the temperature of the heater resistor 2 continues to increase even when the heater resistor 2 is energized when the degree of freezing is low or when it is not frozen. This can be prevented.

  Further, the heater control device 1 is configured such that the resistance value of the heater resistor 2 exceeds the first resistance threshold value and the rate of change of the resistance value of the heater resistor 2 is smaller than the rate of change threshold value, or the resistance value of the heater resistor 2 is the second value. If the outside air temperature detected by the outside air temperature sensor 5 exceeds a predetermined temperature when the resistance threshold is exceeded, the energization to the heater resistor 2 is stopped. If the outside air temperature does not exceed the predetermined temperature, the heater resistance 2 is turned off. By adopting a configuration in which the energization amount is reduced without stopping energization, the power consumption of the heater resistor 2 can be reduced after the frozen state is eliminated, and refreezing when the outside air temperature is low can be prevented.

  In the present embodiment, the heater control device 1 measures the elapsed time from the start of energization of the heater resistor 2 with a timer, and stops energization of the heater resistor 2 when this time exceeds a predetermined time. Although it was set as the structure, it is not restricted to this, The structure which does not perform the energization stop according to the elapsed time from an energization start may be sufficient. In this case, step S3 in the flowchart shown in FIG. 3 may be deleted, and if the de-icer switch is turned on in step S2 (S2: YES), the freeze elimination determination process in step S4 may be performed.

  In addition, the heater control device 1 is configured to perform the process of stopping energization or reducing the energization amount to the heater resistor 2 depending on whether or not the outside air temperature detected by the outside air temperature sensor 5 exceeds a predetermined temperature. However, the heater control device 1 may be configured to stop energization of the heater resistor 2 regardless of the outside air temperature when it is determined that the freezing has been eliminated. In this case, steps S6 and S8 in the flowchart shown in FIG. 3 may be deleted, and if it is determined in step S5 that the freezing has been eliminated (S5: YES), the power supply may be stopped in step S9.

  In addition, the heater control device 1 is configured to reduce the energization amount or stop the energization of the heater resistor 2 when the resistance value of the heater resistor 2 exceeds the second resistance threshold. However, the present invention is not limited to this. The control device 1 may be configured not to perform the determination using the second resistance threshold value. In this case, step S24 in the flowchart shown in FIG. 4 may be deleted, and step S23 may be performed after step S23 is completed.

  Furthermore, the heater control device 1 reduces the energization amount to the heater resistor 2 when the change rate of the resistance value of the heater resistor 2 is smaller than the change rate threshold value and the resistance value of the heater resistor 2 exceeds the first resistance threshold value. However, the present invention is not limited to this, and the heater control device 1 does not make a determination using the first resistance threshold value, that is, the change rate of the resistance value of the heater resistor 2 is smaller than the change rate threshold value. For example, the configuration may be such that the amount of energization to the heater resistor 2 is reduced or energization is stopped regardless of the resistance value. In this case, step S26 in the flowchart shown in FIG. 4 may be deleted, and if it is determined in step S25 that the rate of change is smaller than the rate of change threshold (S25: YES), the process of step S27 may be performed. .

  Further, the de-icer switch 3, the outside air temperature sensor 5, the ammeter 6 and the voltmeter 7 are provided outside the heater control device 1, and an output signal from each device is input to the control unit 11 of the heater control device 1. However, the configuration is not limited to this, and each of these devices may be included in the heater control device 1.

  Moreover, although the heater control apparatus 1 was set as the structure which calculates the resistance value of the heater resistance 2 from the electric current which the ammeter 6 detected, and the voltage which the voltmeter 7 detected, it does not restrict to this. For example, if the circuit configuration is such that the voltage applied to the heater resistor 2 is kept substantially constant, the heater control device 1 acquires only the current value detected by the ammeter 6 without detecting the voltage by the voltmeter 7. The resistance value of the heater resistor 2 may be calculated. Further, for example, if the heater control device 1 is configured to acquire only the current value detected by the ammeter 6, it is possible to determine whether the freezing is eliminated according to the rate of change of the current value without calculating the resistance value of the heater resistor 2. It is good also as a structure which performs electricity supply control to the heater resistance 2. FIG.

1 Heater control device 2 Heater resistance (heater load)
3 Deicer switch 4 IG switch 5 Outside air temperature sensor (outside air temperature detection means)
6 ammeter 7 voltmeter 11 control unit (resistance value acquisition means, calculation means, energization control means, change rate determination means, resistance value determination means, upper limit determination means)
12 Switching element

Claims (6)

In a heater control device that controls energization to a heater load provided in a vehicle,
Resistance value acquisition means for acquiring the resistance value of the heater load in time series;
Calculating means for calculating a rate of change of the resistance value acquired by the resistance value acquiring means;
A heater control device comprising: an energization control unit that performs control to adjust an energization amount to the heater load according to the change rate calculated by the calculation unit. A change rate determining means for determining whether the change rate calculated by the calculating means is smaller than a change rate threshold;
A resistance value determining means for determining whether or not the resistance value acquired by the acquiring means is greater than a resistance threshold;
The energization control unit determines that the change rate is determined to be smaller than the change rate threshold value by the change rate determination unit, and the resistance value is determined to be greater than the resistance threshold value by the resistance value determination unit. The heater control device according to claim 1, wherein an energization amount to the heater load is reduced. Further comprising an upper limit determination means for determining whether or not the resistance value acquired by the acquisition means exceeds an upper limit value;
The energization control means reduces the energization amount to the heater load when the upper limit determination means determines that the resistance value exceeds the upper limit value. The heater control device according to claim 2. The heater control apparatus according to any one of claims 1 to 3, wherein the energization control unit stops energization to the heater load. It further comprises an outside air temperature detecting means for detecting the outside air temperature of the vehicle,
The energization control means includes
When the outside air temperature detected by the outside air temperature detecting means is lower than a predetermined temperature, the energization amount to the heater load is reduced,
The energization to the heater load is stopped when the outside air temperature detected by the outside air temperature detecting means is higher than a predetermined temperature. Heater control device. The heater control device according to any one of claims 1 to 5, wherein the heater load is a heat ray provided on a window glass of the vehicle.

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