Vehicle heater control device

Abstract

To provide a heater control device for a vehicle capable of controlling a heater according to the temperature of a window so as to suppress overheating of the window.SOLUTION: A heater control device 1 includes a heater 3 that heats a window of a vehicle, and an ECU 10 that controls power supplied to the heater 3. The ECU 10 estimates the window temperature which is the temperature of the window on the basis of a predetermined relationship between the estimated power supplied to the heater 3 and the estimated temperature of the window. When the estimated window temperature is higher than a predetermined temperature threshold, the ECU 10 suppresses the power supplied to the heater 3 compared to the heating power supplied to the heater 3 when the estimated window temperature is below the temperature threshold.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a vehicle heater control device.

Background Art

[0002] Conventionally, there is known a vehicle heater control device that supplies electric power to a heater for heating a window to generate heat, in order to remove, for example, fog, ice, or snow adhering to the window of a vehicle (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] Heat from sources other than the heater controlled by the vehicle heater control device (for example, heat from sunlight or another heater) may be applied to the window of the vehicle. Therefore, it is desired to control the heater in accordance with the temperature of the window so as to suppress overheating of the window.

Means for Solving the Problems

[0005] A vehicle heater control device according to one aspect of the present invention includes: a heater that heats a window of a vehicle; and a controller that controls electric power supplied to the heater. The controller estimates the temperature of the window based on a predetermined relationship between estimation-use electric power supplied to the heater and an estimated temperature of the window, and when the estimated temperature is higher than a predetermined threshold, suppresses the electric power supplied to the heater compared to heating-use electric power that is supplied to the heater when the estimated temperature is equal to or lower than the threshold.

[0006] In a vehicle heater control device according to one aspect of the present invention, the temperature of the window is estimated by the controller based on a predetermined relationship between the estimated power supplied to the heater and the estimated temperature of the window. If the estimated temperature is higher than the threshold, the power supplied to the heater is reduced compared to the heating power supplied when the estimated temperature is below the threshold. As a result, when the estimated temperature is higher than the threshold, the amount of heating of the window by the heater is reduced, thereby preventing the window from overheating. Therefore, according to a vehicle heater control device according to one aspect of the present invention, it is possible to control the heater according to the window temperature to prevent the window from overheating.

[0007] In one embodiment, the controller may continue to suppress the power supplied to the heater for a predetermined time if the estimated temperature is higher than the threshold. Even if the power supplied to the heater is suppressed when the estimated temperature is higher than the threshold, it will still take some time for the window temperature to fall below the threshold. Therefore, by continuing to suppress the power supplied to the heater for a predetermined time, the window temperature estimation process can be omitted.

[0008] In one embodiment, the controller supplies heating power to the heater if the estimated temperature is below the threshold, and does not need to supply power to the heater if the estimated temperature is above the threshold. In this case, overheating of the window can be effectively suppressed.

[0009] In one embodiment, the heating power may include a first heating power when the deviation between the estimated temperature and the threshold is greater than or equal to a predetermined deviation threshold, and a second heating power which is less than the first heating power when the deviation is less than the deviation threshold. In this case, the amount of heating of the window by the heater is reduced compared to the case where the first heating power is always supplied to the heater when the estimated temperature is less than or equal to the threshold. Therefore, overheating of the window can be further suppressed. [Effects of the Invention]

[0010] According to one aspect of the present invention, a vehicle heater control device makes it possible to control the heater according to the temperature of the window in order to suppress overheating of the window. [Brief explanation of the drawing]

[0011] [Figure 1] This is a block diagram showing the schematic configuration of a vehicle heater control device according to one embodiment. [Figure 2] Figure 1 is a flowchart showing an example of ECU processing. [Figure 3] This flowchart shows another example of the ECU processing shown in Figure 1. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant descriptions will be omitted.

[0013] Figure 1 is a block diagram showing the schematic configuration of a vehicle heater control device according to one embodiment. The vehicle heater control device 1 shown in Figure 1 (hereinafter simply referred to as "heater control device 1") is installed in a vehicle such as a passenger car and controls a heater that heats the vehicle's windows.

[0014] As shown in Figure 1, the heater control device 1 is equipped with an ECU (Electronic Control Unit) 10 that comprehensively controls the device. The ECU 10 is an electronic control unit consisting of a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. The ECU 10 loads programs stored in ROM into RAM and executes them with the CPU to perform various vehicle controls. The ECU 10 may be composed of multiple electronic control units.

[0015] ECU10 is connected to heater sensor 2 and heater 3.

[0016] The heater sensor 2 is a detector provided on the heater 3. The heater sensor 2 includes at least one of a current sensor that detects the current flowing through the heater 3, and a voltage sensor that detects the voltage applied to the heater 3. The current sensor transmits a detection signal of the detected current to the ECU 10. The voltage sensor transmits a detection signal of the detected voltage to the ECU 10.

[0017] Heater 3 is a heating device that heats the vehicle's window. Heater 3 heats the window, for example, to eliminate fogging or icing that occurs on the window element within the imaging range of a camera mounted on the inside of the vehicle's window. Heater 3 is supplied with power in accordance with a control signal from ECU 10. Heater 3 heats the window, for example, when the defogger switch is in the ON state. Heater 3 includes a conductor through which current flows when power is supplied. Heater 3 may, as an example, be a heating element heater provided on the surface of a glass window.

[0018] Next, the functional configuration of the ECU 10 will be described. The ECU 10 has a temperature estimation unit 11 and a power supply control unit 12. In order to suppress overheating of the window, the ECU 10 estimates the temperature of the window and controls the heater 3 based on the estimated temperature. Note that some of the functions of the ECU 10 described below may be executed in a server that can communicate with the vehicle.

[0019] The temperature estimation unit 11 estimates the window temperature based on a predetermined relationship between the estimated power supplied to the heater 3 and the estimated window temperature. The predetermined relationship refers to a constant relationship between the temperature and resistance of the conductors of the heater 3. The predetermined relationship is, for example, the resistance-temperature characteristic. The resistance-temperature characteristic is, for example, a relationship in which the resistance of a resistor made of a conductor increases monotonically (for example, as a linear function) as the temperature increases. Therefore, there is a one-to-one relationship between the resistance of a conductor and the temperature of the conductor, and the window temperature can be estimated from the resistance. The resistance-temperature characteristic is, for example, a known conversion formula that includes the resistance-temperature coefficient of the conductors constituting the heater 3.

[0020] The estimation power is electric power supplied to the heater 3 for estimating the window temperature. The estimation power has a preset predetermined power value lower than the heating power. For the estimation power, an estimation voltage and an estimation current are preset to predetermined values for estimating the window temperature. The estimation current may be a current flowing through the heater 3 that is reduced by adjusting a separately provided variable resistor or the like.

[0021] The heating power is electric power supplied to the heater 3 for heating the window for the purpose of eliminating fogging or icing. For the heating power, a heating voltage and a heating current are preset to predetermined values for heating the window for the purpose of eliminating fogging or icing.

[0022] The temperature estimation unit 11 calculates an estimated resistance value based on the detection result of the heater sensor 2, and estimates the window temperature using the estimated resistance value. The temperature estimation unit 11 may, for example, in correspondence with a linear function representing the resistance-temperature characteristic, calculate the temperature of the conductor of the heater 3 based on the resistance temperature coefficient and the estimated resistance value, as well as the reference temperature of the heater 3 and the reference resistance value of the heater 3, and estimate the calculated temperature of the heater 3 as the window temperature. The reference temperature and the reference resistance value are preset known reference values used for calculating the temperature of the conductor of the heater 3.

[0023] As an example, the temperature estimation unit 11 may detect the heater current flowing through the heater 3 due to the application of the estimation voltage, based on the detection result of the heater sensor 2. The temperature estimation unit 11 may calculate the estimated resistance value by dividing the estimation voltage applied to the heater 3 by the detected heater current. The temperature estimation unit 11 may estimate the window temperature based on the calculated estimated resistance value and the pre-stored resistance-temperature characteristic of the heater 3.

[0024] As another example, the temperature estimation unit 11 may detect the heater voltage applied to the heater 3 to supply the estimation current based on the detection result of the heater sensor 2. The temperature estimation unit 11 may calculate the estimated resistance value by dividing the detected heater voltage by the estimation current supplied to the heater 3. The temperature estimation unit 11 may estimate the window temperature based on the calculated estimated resistance value and the resistance-temperature characteristics of the heater 3 that have been stored in advance.

[0025] The power supply control unit 12, if the estimated window temperature is higher than a predetermined temperature threshold (threshold), reduces the power supplied to the heater 3 compared to the power supplied to the heater 3 when the estimated window temperature is below the temperature threshold. The temperature threshold is a window temperature threshold used to determine whether or not to reduce the power supplied to the heater 3. The temperature threshold is set in advance based on, for example, the heat resistance of the heater 3. The temperature threshold may be set to a temperature value such that the vehicle's window overheats if the supply of heating power to the heater 3 continues. Window overheating means a state in which there is a high possibility of damage such as window cracking due to excessive heat.

[0026] The power supply control unit 12 determines whether the window temperature is below the temperature threshold. If the window temperature is not below the temperature threshold (i.e., the window temperature is above the temperature threshold), the power supply control unit 12 may choose not to supply power to the heater 3 as a way of suppressing the power supplied to the heater 3. If the window temperature is above the temperature threshold, the power supply control unit 12 may also choose to supply power to the heater 3 that is less than the heating power as a way of suppressing the power supplied to the heater 3.

[0027] The power supply control unit 12 supplies heating power to the heater 3 when the window temperature is below the temperature threshold. The heating power may be changed according to the temperature deviation, which is the difference between the estimated window temperature and the temperature threshold. The temperature deviation is the difference between the estimated window temperature and the temperature threshold when the window temperature is below the temperature threshold. The temperature deviation is calculated, for example, by subtracting the window temperature from the temperature threshold, and is a positive value that increases as the window temperature decreases.

[0028] The heating power may include, for example, a first heating power when the temperature deviation is greater than or equal to a deviation threshold, and a second heating power when the temperature deviation is less than the deviation threshold. The deviation threshold is a temperature deviation threshold used to determine whether or not to switch the heating power for heating the heater 3. The deviation threshold can be, for example, a predetermined temperature within a range in which overheating of the window is unlikely to occur even when the first heating power is supplied to the heater 3 to heat the window.

[0029] The first heating power can be set to a value that prioritizes the heater 3 heating the window. With the first heating power, the first heating voltage and first heating current are preset to predetermined values ​​for heating the window to eliminate fogging or freezing. The second heating power can be set to a value smaller than the first heating power, with the aim of suppressing overheating of the window. With the second heating power, the second heating voltage and second heating current are preset to predetermined values ​​for heating the window while suppressing overheating.

[0030] The power supply control unit 12 may continue to suppress the power supplied to the heater 3 for a predetermined time if the estimated window temperature is higher than the temperature threshold. The predetermined time is the time required to wait for the window temperature to decrease before performing the next heater control processing of the ECU 10. The predetermined time is not particularly limited, but may be set in advance, for example, by considering the degree of decrease in window temperature while the power supplied to the heater 3 is suppressed. The predetermined time may also be 0.

[0031] Next, an example of the processing of the ECU 10 of the heater control device 1 will be explained with reference to Figure 2. Figure 2 is a flowchart showing an example of the processing of the ECU in Figure 1. The processing shown in the flowchart in Figure 2 is repeated at a predetermined cycle, for example, when the defogger switch for heater 3 is in the ON state.

[0032] As shown in Figure 2, in step S01, the ECU 10 supplies estimated power via the power supply control unit 12. The temperature estimation unit 11 supplies estimated power by, for example, applying a predetermined estimated voltage lower than the heating voltage to the heater 3.

[0033] In step S02, the ECU 10 detects the heater current using the temperature estimation unit 11. The temperature estimation unit 11 detects the heater current flowing through the heater 3 by applying an estimation voltage, for example, based on the detection result of the heater sensor 2.

[0034] In step S03, the ECU 10 calculates the estimated resistance value using the temperature estimation unit 11. The temperature estimation unit 11 calculates the estimated resistance value by, for example, dividing the estimation voltage applied to the heater 3 by the detected heater current.

[0035] In step S04, the ECU 10 estimates the window temperature using the temperature estimation unit 11. The temperature estimation unit 11 estimates the window temperature based on the calculated estimated resistance value and the temperature resistance characteristics of the heater 3 that have been stored in advance, by using the fact that the resistance value of the conductors constituting the heater 3 changes according to the temperature of the conductors.

[0036] In step S05, the ECU 10, using the power supply control unit 12, determines whether the window temperature is below the temperature threshold. If the ECU 10 determines that the window temperature is not below the temperature threshold (i.e., the window temperature is higher than the temperature threshold) (step S05: NO), it proceeds to step S06. On the other hand, if the ECU 10 determines that the window temperature is below the temperature threshold (step S05: YES), it proceeds to step S07 and supplies heating power to the heater 3.

[0037] In step S06, the ECU 10, via the power supply control unit 12, disables power supply and enters standby mode. The power supply control unit 12 does not supply power to the heater 3. By remaining in standby mode without supplying power to the heater 3, the power supply control unit 12 continues to suppress the power supplied to the heater 3 for a predetermined period of time. After that, the process shown in Figure 2 is terminated.

[0038] In step S07, the ECU 10, using the power supply control unit 12, determines whether the temperature deviation is greater than or equal to the deviation threshold. If the ECU 10 determines that the temperature deviation is greater than or equal to the deviation threshold (step S07: YES), it proceeds to step S08. On the other hand, if the ECU 10 determines that the temperature deviation is not greater than or equal to the deviation threshold (the temperature deviation is less than the deviation threshold) (step S07: NO), it proceeds to step S09.

[0039] In step S08, the ECU 10 supplies the first heating power via the power supply control unit 12. The power supply control unit 12 supplies the first heating power to the heater 3, for example, by applying the first heating voltage to the heater 3. After that, the process shown in Figure 2 is terminated.

[0040] In step S09, the ECU 10 supplies the second heating power via the power supply control unit 12. The power supply control unit 12 supplies the second heating power to the heater 3, for example, by applying a second heating voltage to the heater 3. After that, the process shown in Figure 2 is terminated.

[0041] The processing of the ECU 10 of the heater control device 1 is not limited to the processing shown in Figure 2 above. For example, the temperature estimation unit 11 may supply an estimation current to the heater 3 instead of applying an estimation voltage as the power supply for estimation. The temperature estimation unit 11 calculated the estimated resistance value from the heater current, but it may also calculate the estimated resistance value from the heater voltage.

[0042] Furthermore, it is not mandatory for the power supply control unit 12 to withhold power and remain in standby mode when the window temperature is higher than the temperature threshold. When the window temperature is higher than the temperature threshold, the power supply control unit 12 only needs to reduce the power supplied to the heater 3 compared to the heating power supplied to the heater 3 when the window temperature is below the temperature threshold. When the window temperature is higher than the temperature threshold, the power supply control unit 12 may estimate the next window temperature without continuing to reduce the power supplied to the heater 3 (the predetermined time for continuing to reduce the power supplied to the heater 3 may be 0).

[0043] Another example of the processing of the ECU 10 of the heater control device 1 will be explained with reference to Figure 3. Figure 3 is a flowchart showing another example of the processing of the ECU in Figure 1. The processing shown in the flowchart in Figure 3 is repeated at a predetermined period, for example, when the defogger switch for heater 3 is in the ON state.

[0044] As shown in Figure 3, in step S11, the ECU 10 supplies estimation power via the power supply control unit 12. The temperature estimation unit 11 supplies estimation power, for example, by flowing a predetermined estimation current, which is smaller than the heating current, to the heater 3.

[0045] In step S12, the ECU 10 detects the heater voltage using the temperature estimation unit 11. The temperature estimation unit 11 detects the heater voltage applied to the heater 3 in order to supply an estimation current, for example, based on the detection result of the heater sensor 2.

[0046] In step S13, the ECU 10 calculates the estimated resistance value using the temperature estimation unit 11. The temperature estimation unit 11 calculates the estimated resistance value by, for example, dividing the detected heater voltage by the estimation current flowing through the heater 3.

[0047] In step S14, the ECU 10 uses the temperature estimation unit 11 to estimate the window temperature. The temperature estimation unit 11 estimates the window temperature based on the calculated estimated resistance value and the temperature resistance characteristics of the heater 3 that have been stored in advance, by using the fact that the resistance value of the conductors constituting the heater 3 changes according to the temperature of the conductors.

[0048] In step S15, the ECU 10, using the power supply control unit 12, determines whether the window temperature is below the temperature threshold. If the ECU 10 determines that the window temperature is not below the temperature threshold (i.e., the window temperature is higher than the temperature threshold) (step S15: NO), it proceeds to step S16. On the other hand, if the ECU 10 determines that the window temperature is below the temperature threshold (step S15: YES), it proceeds to step S17.

[0049] In step S16, the ECU 10, through the power supply control unit 12, suppresses power. The power supply control unit 12 suppresses power by supplying the heater 3 with less power than the heating power supplied to the heater 3 in step S17. After that, there is no predetermined waiting time, and the process shown in Figure 3 is terminated.

[0050] In step S17, the ECU 10 supplies heating power via the power supply control unit 12. The power supply control unit 12 supplies heating power to the heater 3 by applying a voltage similar to the first heating voltage in step S08 of Figure 2 to the heater 3. After that, the process shown in Figure 3 is terminated.

[0051] As explained above, in the heater control device 1, the window temperature is estimated by the ECU 10 based on a predetermined relationship between the estimated power supplied to the heater 3 and the estimated temperature of the window. If the estimated window temperature is higher than a predetermined temperature threshold, the power supplied to the heater 3 is reduced compared to the heating power supplied to the heater 3 when the estimated window temperature is below the temperature threshold. As a result, when the estimated window temperature is higher than the temperature threshold, the amount of heating of the window by the heater 3 is reduced, thereby suppressing overheating of the window. Therefore, the heater control device 1 makes it possible to control the heater 3 according to the window temperature to suppress overheating of the window.

[0052] In the heater control device 1, the ECU 10 continues to suppress the power supplied to the heater 3 for a predetermined time if the estimated window temperature is higher than the temperature threshold. Even if the power supplied to the heater 3 is suppressed when the estimated window temperature is higher than the temperature threshold, it will take some time for the window temperature to fall below the temperature threshold. Therefore, by continuing to suppress the power supplied to the heater 3 for a predetermined time, the window temperature estimation process can be omitted.

[0053] In the heater control device 1, the ECU 10 supplies heating power to the heater 3 if the estimated window temperature is below the temperature threshold, and does not supply power to the heater 3 if the estimated window temperature is above the temperature threshold. This effectively suppresses overheating of the window.

[0054] In the heater control device 1, the heating power includes a first heating power when the temperature deviation between the estimated window temperature and the temperature threshold is greater than or equal to a predetermined deviation threshold, and a second heating power which is less than the first heating power when the temperature deviation is less than the deviation threshold. As a result, the amount of heating of the window by the heater is reduced compared to when the first heating power is always supplied to the heater when the window temperature is below the temperature threshold. Therefore, overheating of the window can be further suppressed.

[0055] [Differentiation] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above. The present invention can be implemented in various forms, starting with the embodiments described above, by making various changes and improvements based on the knowledge of those skilled in the art.

[0056] In the heater control device 1 described above, the estimated power has a predetermined power value that is lower than the heating power, and the estimated voltage is smaller than the heating power, or the estimated current is smaller than the heating current, but the device is not limited to these examples. For example, instead of reducing the voltage value from the heating power, the amount of energy as a time average may be reduced by adjusting the application time between the heating power voltage value and 0V using duty cycle control, and this reduced energy may be used as the estimated power. In this case, the temperature estimation unit 11 may, for example, calculate the estimated resistance value using the average voltage and current over a certain period, and estimate the window temperature.

[0057] In the embodiment described above, a glass window was used as an example, but a resin window may also be used. In this case, the heater control device 1 can suppress thermal degradation due to overheating.

[0058] In the embodiment described above, the first heating power and the second heating power were switched using a single deviation threshold, resulting in a step-like switching point for the heating power. However, the invention is not limited to this example. For example, the heating power may be switched using two or more deviation thresholds, resulting in a step-like switching point for the heating power. The heating power may change linearly or remain constant regardless of the temperature deviation. Note that the use of deviation thresholds is not mandatory.

[0059] In the embodiments described above, the heater 3 was, for example, a heat-wire heater provided on the surface of a glass window, but is not limited to this example. The heater 3 may also be a heating device that indirectly heats the vehicle window. For example, the heater 3 may have a heat source provided at a distance from the window. In this case, the heat from the heater 3 can be transferred to the window by means of radiation or warm air using a blower, for example.

[0060] In the embodiment described above, the heater 3 heated the window to eliminate fogging or icing that occurred on the window member, but the invention is not limited to this example. Installation of a camera on the window is not mandatory.

[0061] In the embodiment described above, the temperature estimation unit 11 detected the heater current or heater voltage and calculated the estimated resistance value to estimate the window temperature, but calculating the resistance value is not essential. For example, the temperature estimation unit 11 may estimate the window temperature using a pre-set map or the like that represents the relationship between the heater current or heater voltage and the window temperature when estimation power is supplied to the heater 3. In short, the temperature estimation unit 11 only needs to estimate the window temperature based on a predetermined relationship between the estimation power supplied to the heater 3 and the estimated temperature of the window.

[0062] In the embodiment described above, a configuration in which the heater sensor 2 is provided on the heater 3 was illustrated, but it may also be built into the ECU 10. [Explanation of Symbols]

[0063] 1... Heater control unit, 3... Heater, 10... ECU (controller).

Claims

1. A heater that heats the vehicle's windows, The system includes a controller that controls the power supplied to the heater, The aforementioned controller, Based on a predetermined relationship between the estimated power supplied to the heater and the estimated temperature of the window, the temperature of the window is estimated. A vehicle heater control device that, if the estimated temperature is higher than a predetermined threshold value set to the temperature at which overheating of the window occurs due to the continued supply of heating power to the heater, suppresses the power supplied to the heater compared to the heating power supplied to the heater when the estimated temperature is below the threshold value.

2. The heating power is power supplied to the heater for the purpose of heating the window to eliminate fogging or freezing of the window, The heater control device for a vehicle according to claim 1, wherein the estimated power has a predetermined power value that is lower than the heating power.

3. The heater control device for a vehicle according to claim 1 or 2, wherein the controller continues to suppress the power supplied to the heater for a predetermined time if the estimated temperature is higher than the threshold.

4. The aforementioned controller, If the estimated temperature is below the threshold, the heating power is supplied to the heater. A heater control device for a vehicle according to claim 1 or 2, wherein if the estimated temperature is higher than the threshold, power is not supplied to the heater.

5. The heater control device for a vehicle according to claim 4, wherein the heating power includes a first heating power when the deviation between the estimated temperature and the threshold is greater than or equal to a predetermined deviation threshold, and a second heating power which is less than the first heating power when the deviation is less than the deviation threshold.

Images