Vehicle-mounted device and method for controlling vehicle-mounted device

Abstract

To supply sufficient power from a capacitor to a load when a device temperature is shifted within an operation guarantee temperature while suppressing reduction in the life of the capacitor.SOLUTION: An in-vehicle device according to an aspect of an embodiment includes a controller that controls a charging voltage for a capacitor that supplies electric power to a load. The controller lowers the charging voltage to be lower than the normal voltage when a device temperature indicating a temperature of the in-vehicle device becomes equal to or higher than an upper limit threshold value set higher than an operation guarantee temperature of the in-vehicle device. When the device temperature becomes equal to or lower than a restoration threshold set between the upper limit threshold and the operation guarantee temperature after the charging voltage is reduced, the controller restores the reduced charging voltage to the normal voltage.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The disclosed embodiments relate to an in-vehicle device and a control method for the in-vehicle device. [Background technology]

[0002] Conventionally, in-vehicle devices are known that include a capacitor (e.g., an electric double-layer capacitor) as a backup power source for supplying power to a load. The lifespan of such a capacitor shortens as the temperature increases and as the charging voltage (applied voltage) to the capacitor increases. In particular, when the temperature exceeds an upper threshold (e.g., 85°C) set higher than the guaranteed operating temperature of the in-vehicle device, the lifespan may be rapidly shortened if the charging voltage cannot be sufficiently reduced. Therefore, it is considered to significantly reduce the charging voltage when the device temperature, which indicates the temperature of the in-vehicle device, exceeds the upper threshold. However, if the device temperature returns to the guaranteed operating temperature after the charging voltage is reduced, the charge in the capacitor may become insufficient, resulting in an insufficient power supply to the load.

[0003] Additionally, various methods for controlling equipment that take into account temperature-related lifespans have been proposed (see, for example, Patent Document 1). In conventional technology, a determination is made as to whether the operating temperature of the controller of an electric vehicle is too high, and if the operating temperature is too high, the current supplied is adjusted to decrease, thereby improving the safety and useful lifespan of the electric vehicle when it is in operation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-26919 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the prior art, when the device temperature transitions to within the guaranteed operating temperature range after the charging voltage of the capacitor is reduced, a problem may arise in that the capacitor cannot supply sufficient power to the load.

[0006] One aspect of the embodiment has been made in consideration of the above, and aims to provide an on-board device and a control method for an on-board device that can supply sufficient power from a capacitor to a load when the device temperature transitions to within the guaranteed operating temperature range while suppressing a decrease in the capacitor's lifespan. [Means for solving the problem]

[0007] To solve the above problems and achieve the object, an in-vehicle device according to one aspect of the embodiment includes a controller that controls a charging voltage for a capacitor that supplies power to a load. The controller reduces the charging voltage to a lower than normal voltage when a device temperature indicating the temperature of the in-vehicle device reaches or exceeds an upper threshold value set higher than the guaranteed operating temperature of the in-vehicle device. The controller restores the reduced charging voltage to the normal voltage when the device temperature after reducing the charging voltage reaches or exceeds a recovery threshold value set between the upper threshold value and the guaranteed operating temperature. [Effects of the Invention]

[0008] In one aspect of the embodiment, the controller reduces the capacitor's charging voltage to a value lower than the normal voltage when the device temperature reaches or exceeds an upper threshold value set higher than the guaranteed operating temperature of the in-vehicle device. By reducing the capacitor's charging voltage when the device temperature is excessively high, that is, equal to or higher than the upper threshold value, the capacitor's lifespan can be reduced. Furthermore, the controller restores the reduced charging voltage to the normal voltage when the device temperature falls below a recovery threshold value set between the upper threshold value and the guaranteed operating temperature after reducing the charging voltage. This allows the capacitor's charging voltage to be restored to the normal voltage when the device temperature transitions back to within the guaranteed operating temperature range, thereby enabling the capacitor to supply sufficient power to the load. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram showing an example of the configuration of an in-vehicle system including an in-vehicle device according to an embodiment. [Figure 2] FIG. 2 is a time chart for explaining the control of the charging voltage performed by the microcomputer. [Figure 3] FIG. 3 is a flowchart showing an example of processing executed by the microcomputer of the in-vehicle device according to the embodiment. [Figure 4] FIG. 4 is a flowchart showing an example of processing executed by a microcomputer in an in-vehicle device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The following describes in detail an embodiment of an in-vehicle device and a control method for an in-vehicle device disclosed in the present application with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiments.

[0011] (Embodiment) An in-vehicle system including an in-vehicle device according to an embodiment will be described with reference to Fig. 1. Fig. 1 is an explanatory diagram showing a configuration example of an in-vehicle system 1 including an in-vehicle device 10 according to an embodiment. Note that, although the following description will be given taking an example in which the in-vehicle device 10 is a drive recorder, the present invention is not limited to this, and the in-vehicle device 10 may be other types of devices such as a navigation device.

[0012] 1, the in-vehicle system 1 includes a battery 100 and an in-vehicle device 10. The battery 100 is mounted on a vehicle. The battery 100 is a main battery (main power source) that supplies power to the in-vehicle device 10 and the like. The battery 100 may be a lead battery or a lithium-ion battery.

[0013] The in-vehicle device 10 is electrically connected to a battery 100. The in-vehicle device 10 includes a DC / DC converter (hereinafter referred to as "DCDC") 20, a load 30, a capacitor 40, voltage dividing resistors 51 and 52, a thermistor 53, a transistor 54, a temperature sensor 60, and a microcomputer 70.

[0014] The DCDC 20 steps down the voltage of the battery 100 and supplies power to the load 30, etc. The DCDC 20 also steps down the voltage of the battery 100 and supplies the stepped down voltage to the capacitor 40 as a charging voltage. The capacitor 40 is charged by the supply of this charging voltage. The charging voltage is changed (variable) by voltage dividing resistors 51 and 52, a thermistor 53, and a transistor 54, which will be described later.

[0015] The load 30 is a load for operating the in-vehicle device 10, which is a drive recorder. For example, the load 30 includes a main microcomputer that executes various controls, such as image capture control and video recording control, in the drive recorder. The load 30 may also include other loads (devices), such as a camera that captures images of the vehicle's surroundings and the interior of the vehicle. The main microcomputer is a microcomputer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The main microcomputer may be partially or entirely configured with hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The main microcomputer performs, for example, video recording control, such as recording images captured by a camera to an internal memory or a portable storage medium (e.g., an SD card).

[0016] The capacitor 40 is a backup power supply that supplies power to the load 30. The capacitor 40 is an electric double layer capacitor (EDLC). Hereinafter, the capacitor 40 may be referred to as the "EDLC 40." The EDLC 40 is connected between the DCDC 20 and the load 30. Specifically, the EDLC 40 is connected between a power line connecting the DCDC 20 and the load 30 and a ground potential (ground). When the power line connecting the in-vehicle device 10 and the battery 100 is disconnected due to an impact such as a vehicle collision, the EDLC 40 supplies power to the load 30 by discharging the charge accumulated through charging. As a result, in the in-vehicle device 10, even when power is not supplied from the battery 100 due to a power line disconnection, power can be supplied from the EDLC 40 to the load 30. This makes it possible to reliably perform video recording control for recording images before and after a vehicle collision, for example.

[0017] The life of the EDLC 40 becomes shorter as the temperature increases and as the charging voltage (applied voltage) to the EDLC 40 increases.

[0018] The voltage-dividing resistors 51 and 52 are connected between the DCDC 20 and the load 30. In other words, the voltage-dividing resistors 51 and 52 are connected between the DCDC 20 and the EDLC 40. More specifically, the voltage-dividing resistors 51 and 52 are connected between the power line connecting the DCDC 20 and the EDLC 40 and ground potential. The voltage-dividing resistors 51 and 52 divide the output voltage from the DCDC 20. The divided voltage is input to the DCDC 20 as a feedback voltage FB. Although not shown, the DCDC 20 includes an electrical circuit that controls transistors and the like so that the feedback voltage FB matches a reference voltage. This electrical circuit controls the output voltage from the DCDC 20 to be constant at a predetermined voltage. Note that the predetermined voltage is the output voltage when the temperature of the in-vehicle device 10 is within the guaranteed operating temperature range. Therefore, hereinafter, the predetermined voltage may be referred to as the "normal voltage." For ease of understanding, the normal voltage is set to "4.6 V," but this is merely an example and is not limiting. The "guaranteed operating temperature" is a preset value that indicates the temperature at which the in-vehicle device 10 is guaranteed to perform various operations such as capturing and recording images when the temperature of the in-vehicle device 10 is at or below that temperature. For ease of understanding, the guaranteed operating temperature is set to "75°C", but this is merely an example and is not limiting.

[0019] The thermistor 53 has a function of decreasing the output voltage from the DCDC 20 as the temperature of the in-vehicle device 10 increases. Specifically, the thermistor 53 is connected in parallel with the voltage dividing resistor 51. The resistance of the thermistor 53 gradually decreases as the temperature of the in-vehicle device 10 increases. The decrease in the resistance of the thermistor 53 changes the feedback voltage FB, and the output voltage from the DCDC 20 gradually decreases. As a result, when the temperature of the in-vehicle device 10 increases and becomes relatively high, the charging voltage from the DCDC 20 to the EDLC 40 can be reduced, and the shortening of the life of the EDLC 40 can be suppressed.

[0020] The transistor 54 has a function of relatively significantly reducing the output voltage from the DCDC 20 as the temperature of the in-vehicle device 10 rises. Specifically, the transistor 54 is connected in parallel with the voltage dividing resistor 51 and the thermistor 53. The transistor 54 is an NPN transistor. The collector of the transistor 54 is connected to the output voltage side of the DCDC 20. The base of the transistor 54 is connected to the microcomputer 70. The emitter of the transistor 54 is connected to the feedback voltage FB side of the DCDC 20. The emitter of the transistor 54 is also grounded via the voltage dividing resistor 52.

[0021] The transistor 54 configured as described above is turned on when the temperature of the in-vehicle device 10 rises excessively, significantly reducing the output voltage from the DCDC 20. Specifically, when the temperature of the in-vehicle device 10 reaches or exceeds an upper threshold value set higher than the guaranteed operating temperature, the transistor 54 is turned on by applying a voltage to its base in response to an output signal from the microcomputer 70. When the transistor 54 is turned on, the current from the DCDC 20 bypasses the voltage-dividing resistor 51 and the thermistor 53, causing a significant change in the feedback voltage FB and a significant reduction in the output voltage from the DCDC 20. Specifically, the output voltage (charging voltage) from the DCDC 20 to the EDLC 40 drops from a normal voltage to a limit voltage lower than the normal voltage. For ease of understanding, the upper threshold value is set to "85°C" and the limit voltage is set to "3.6V," but these are merely examples and are not limiting.

[0022] In this manner, in this embodiment, when the temperature of the in-vehicle device 10 is excessively high, equal to or higher than the upper threshold, the charging voltage of the EDLC 40 is reduced, thereby suppressing a reduction in the life span of the EDLC 40.

[0023] Here, after the charging voltage of the EDLC 40 is reduced, for example, the vehicle air conditioner may be operated by a user operation, causing the temperature of the in-vehicle device 10 to drop and transition to within the guaranteed operating temperature range. In such a case, if the charging voltage of the EDLC 40 is left reduced, the EDLC 40 will not have enough charge and will not be able to supply sufficient power to the load 30. Therefore, in this embodiment, when the temperature of the in-vehicle device 10 drops below a recovery threshold set between the upper limit threshold and the guaranteed operating temperature after the charging voltage is reduced, the reduced charging voltage is restored to the normal voltage, which will be described later with reference to FIG. 2.

[0024] The temperature sensor 60 detects a device temperature indicating the temperature of the in-vehicle device 10. For example, the temperature sensor 60 measures the temperature of the EDLC 40 and detects the temperature of the EDLC 40 as the device temperature. The temperature sensor 60 outputs a signal indicating the detected device temperature to the microcomputer 70.

[0025] In the above, an example has been shown in which the temperature sensor 60 directly measures the temperature of the EDLC 40, but the present invention is not limited to this. For example, the temperature sensor 60 may measure the temperature of an electronic component (e.g., an integrated circuit such as an RTC (Real Time Clock)) present near the EDLC 40 or the temperature inside the vehicle cabin, and estimate the temperature of the EDLC 40 (device temperature) from the measured temperature. In other words, the temperature sensor 60 may indirectly measure the temperature of the EDLC 40 (device temperature).

[0026] The microcomputer 70 is a microcomputer having a CPU, ROM, RAM, etc. The microcomputer 70 corresponds to an example of a controller. The microcomputer 70 may be configured in part or in whole using hardware such as an ASIC or FPGA. The microcomputer 70 realizes functions corresponding to the control method for the in-vehicle device 10 according to the embodiment by having the CPU execute a program stored in the ROM using the RAM as a working area.

[0027] The microcomputer 70 controls the charging voltage for the EDLC 40. Specifically, the microcomputer 70 controls the charging voltage for the EDLC 40 in accordance with the device temperature detected by the temperature sensor 60. In other words, the microcomputer 70 controls the output voltage (charging voltage) supplied from the DCDC 20 to the EDLC 40 in accordance with the device temperature.

[0028] The control of the charging voltage performed by the microcomputer 70 will be described with reference to Fig. 2. Fig. 2 is a time chart for explaining the control of the charging voltage performed by the microcomputer 70.

[0029] As shown in Fig. 2, in this embodiment, the above-mentioned restoration threshold is set in advance. The restoration threshold is set between an upper threshold (e.g., 85°C) and an operation guarantee temperature (e.g., 75°C). In other words, the restoration threshold is set to a value that is smaller than the upper threshold and greater than the operation guarantee temperature. Note that, although the restoration threshold is set to "82°C" here, this is merely an example and is not limiting.

[0030] 2, the device temperature rises from time T0 to time T1. This rise in device temperature is caused, for example, by the vehicle being parked outdoors for a long period of time during the day. Furthermore, the device temperature may also rise when the in-vehicle device 10 operates to capture images, record video, or the like while the vehicle is parked.

[0031] From time T0 to time T1, the charging voltage of the EDLC 40 gradually decreases due to the influence of the thermistor 53. More specifically, the charging voltage of the EDLC 40 gradually decreases from the normal voltage (4.6V).

[0032] Next, when the device temperature becomes equal to or higher than the upper limit threshold (see time T1), the microcomputer 70 reduces the charging voltage of the EDLC 40 to a limit voltage (3.6 V) that is lower than the normal voltage. Specifically, the microcomputer 70 outputs an output signal to the transistor 54 (see FIG. 1) to apply a voltage to the base, turning on the transistor 54. As a result, the charging voltage from the DCDC 20 to the EDLC 40 is reduced to the limit voltage (3.6 V) that is lower than the normal voltage.

[0033] Next, at time T2, for example, the user operates the vehicle's air conditioner, gradually decreasing the device temperature. At time T3, when the device temperature falls below the recovery threshold, the microcomputer 70 restores the reduced charging voltage of the EDLC 40 to the normal voltage. Specifically, the microcomputer 70 stops the output signal to the transistor 54 to turn off the transistor 54. As a result, the charging voltage from the DCDC 20 to the EDLC 40 gradually returns (increases) from the limited voltage to the normal voltage. Then, at time T4, the charging voltage of the EDLC 40 reaches the normal voltage, completing the restoration to the normal voltage.

[0034] The device temperature continues to gradually decrease thereafter, and at time T5, the device temperature falls below the guaranteed operating temperature. In other words, the device temperature transitions to within the guaranteed operating temperature range. In this embodiment, even when the device temperature transitions to within the guaranteed operating temperature range, the charging voltage of the EDLC 40, which had been reduced before the transition to the guaranteed operating temperature range, is restored to the normal voltage, so that sufficient power can be supplied from the EDLC 40 to the load 30. In other words, in this embodiment, after time T5 when the device temperature transitions to within the guaranteed operating temperature range, sufficient and reliable power can be supplied from the EDLC 40 to the load 30, thereby ensuring that the in-vehicle device 10 can perform various operations.

[0035] Here, the setting of the recovery threshold will be described in detail. The recovery threshold is set to a value that allows the charging voltage of the EDLC 40 to return to the normal voltage before the device temperature reaches the guaranteed operating temperature. Specifically, as shown in FIG. 2, the time a from when the device temperature drops below the recovery threshold to when it reaches the guaranteed operating temperature is the time from time T3 to time T5. On the other hand, when the device temperature drops below the recovery threshold, the microcomputer 70 returns the reduced charging voltage of the EDLC 40 to the normal voltage. The recovery time b required for this recovery of the charging voltage is the time from time T3 to time T4. The recovery threshold according to this embodiment is set so that the recovery time b is shorter than the recovery time a (recovery time b<recovery time a). As a result, in this embodiment, the reduced charging voltage of the EDLC 40 can be reliably returned to the normal voltage before the device temperature transitions to within the guaranteed operating temperature range.

[0036] Next, a process executed by the microcomputer 70 of the in-vehicle device 10 according to the embodiment will be described with reference to Fig. 3. Fig. 3 is a flowchart showing an example of a process executed by the microcomputer 70 of the in-vehicle device 10 according to the embodiment. The microcomputer 70 repeatedly executes the process shown in Fig. 3.

[0037] 3, the microcomputer 70 detects the device temperature (step S10). Specifically, the microcomputer 70 detects the device temperature in response to a signal output from the temperature sensor 60.

[0038] Next, the microcomputer 70 determines whether the detected device temperature is equal to or greater than the upper threshold (step S11). If the microcomputer 70 determines that the device temperature is not equal to or greater than the upper threshold (step S11, No), in other words, if the device temperature is less than the upper threshold, it ends the process.

[0039] On the other hand, if it is determined that the device temperature is equal to or higher than the upper threshold (step S11, Yes), in other words, if the device temperature is equal to or higher than the upper threshold and is excessively high, the microcomputer 70 reduces the charging voltage of the EDLC 40 (step S12). More specifically, the microcomputer 70 turns on the transistor 54 (see FIG. 1) and reduces the charging voltage of the EDLC 40 to a limit voltage that is lower than the normal voltage.

[0040] In a state where the charging voltage of the EDLC 40 is reduced, the microcomputer 70 detects the device temperature (step S13). Next, the microcomputer 70 determines whether the detected device temperature has become equal to or lower than the recovery threshold value (step S14).

[0041] If the microcomputer 70 determines that the detected device temperature is not equal to or lower than the recovery threshold (step S14, No), the process returns to step S13. On the other hand, if the microcomputer 70 determines that the device temperature is equal to or lower than the recovery threshold (step S14, Yes), the microcomputer 70 restores the reduced charging voltage of the EDLC 40 to the normal voltage (step S15). More specifically, the microcomputer 70 turns off the transistor 54 (see FIG. 1) and restores the charging voltage of the EDLC 40 from the limited voltage to the normal voltage.

[0042] As described above, the in-vehicle device 10 according to the embodiment includes a microcomputer (an example of a controller) 70 that controls the charging voltage for the EDLC (an example of a capacitor) 40 that supplies power to the load 30. The microcomputer 70 reduces the charging voltage to be lower than the normal voltage when the device temperature, which indicates the temperature of the in-vehicle device 10, reaches or exceeds an upper threshold value set higher than the guaranteed operating temperature of the in-vehicle device 10. The microcomputer 70 restores the reduced charging voltage to the normal voltage when, after the device temperature has been reduced, the device temperature reaches or falls below a restoration threshold value set between the upper threshold value and the guaranteed operating temperature.

[0043] The microcomputer 70 according to this embodiment reduces the charging voltage of the EDLC 40 to a value lower than the normal voltage when the device temperature reaches or exceeds an upper threshold value set higher than the guaranteed operating temperature of the in-vehicle device 10. In this manner, by reducing the charging voltage of the EDLC 40 when the device temperature is excessively high, that is, equal to or higher than the upper threshold value, shortening of the lifespan of the EDLC 40 can be suppressed. Furthermore, the microcomputer 70 restores the reduced charging voltage to the normal voltage when the device temperature falls below a recovery threshold value set between the upper threshold value and the guaranteed operating temperature after reducing the charging voltage. This allows the charging voltage of the EDLC 40 to be restored to the normal voltage when the device temperature transitions back within the guaranteed operating temperature range, thereby enabling the EDLC 40 to supply sufficient power to the load 30.

[0044] The capacitor according to this embodiment is an EDLC (electric double layer capacitor) 40. Therefore, in this embodiment, it is possible to suppress a decrease in the lifespan of the EDLC 40, which is a capacitor, and to supply sufficient power from the EDLC 40 to the load when the device temperature transitions to within the guaranteed operating temperature range.

[0045] Although the capacitor is an EDLC 40 in the above example, the present invention is not limited to this, and may be a capacitor that deteriorates due to an increase in temperature or charging voltage, such as an electrolytic capacitor.

[0046] (Variation) Next, an in-vehicle device 10 according to a modified example will be described. In the above embodiment, an example in which the recovery threshold is set in advance is shown, but this is not limiting and the recovery threshold may be set variably. Specifically, in the modified example, the recovery threshold is set according to the degree of decrease in the device temperature.

[0047] Here, the processing executed by the microcomputer 70 of the in-vehicle device 10 according to the modified example will be described with reference to Fig. 4. Fig. 4 is a flowchart showing an example of the processing executed by the microcomputer 70 of the in-vehicle device 10 according to the modified example. Note that in Fig. 4, the same processing as in the embodiment will be assigned the same step numbers, and the description thereof may be omitted.

[0048] As shown in FIG. 4, after the process of step S10, if it is determined in step S11 that the device temperature is equal to or higher than the upper limit threshold, the microcomputer 70 proceeds to step S12 and reduces the charging voltage of the EDLC 40.

[0049] In a state in which the charging voltage of the EDLC 40 is reduced, the microcomputer 70 detects the device temperature (step S12a). Next, the microcomputer 70 determines whether the detected device temperature has decreased (step S12b). For example, if the device temperature detected this time is lower than the device temperature detected last time, the microcomputer 70 determines that the device temperature has decreased.

[0050] If the microcomputer 70 determines that the device temperature has not decreased (step S12b, No), the process returns to step S12a. On the other hand, if the microcomputer 70 determines that the device temperature has decreased (step S12b, Yes), the microcomputer 70 calculates the degree of decrease of the device temperature from the upper limit threshold to the guaranteed operating temperature (step S12c). For example, the microcomputer 70 calculates the slope of the device temperature after time T2 in FIG. 2, and uses the calculated slope as the degree of decrease of the device temperature.

[0051] Next, the microcomputer 70 sets the recovery threshold value according to the calculated degree of decrease in the device temperature (step S12d). Specifically, the microcomputer 70 sets the recovery threshold value according to the degree of decrease in the device temperature so that the recovery of the charging voltage to the normal voltage is completed before the device temperature reaches the guaranteed operating temperature. More specifically, the microcomputer 70 calculates the time it takes for the device temperature to reach the guaranteed operating temperature from the upper limit threshold value from the calculated degree of decrease in the device temperature, and sets the recovery threshold value so that the recovery of the charging voltage to the normal voltage is completed before the device temperature reaches the guaranteed operating temperature.

[0052] After setting the recovery threshold, the microcomputer 70 proceeds to the processing of step S13 and subsequent steps. Specifically, if it is determined that the device temperature detected in step S13 has become equal to or lower than the recovery threshold (step S14, Yes), the microcomputer 70 proceeds to step S15 and recovers the reduced charging voltage of the EDLC 40 to the normal voltage.

[0053] In this way, the microcomputer 70 according to the modified example sets the recovery threshold value according to the degree of drop in the device temperature so that the recovery of the charging voltage to the normal voltage is completed before the device temperature reaches the guaranteed operating temperature. In the modified example, by setting the recovery threshold value as described above, the charging voltage of the EDLC 40, which has been reduced, can be reliably returned to the normal voltage before the device temperature transitions to within the guaranteed operating temperature range.

[0054] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0055] 10 Onboard equipment 30 Load 40 EDLC 70 Microcomputer

Claims

1. An in-vehicle device including a controller that controls a charging voltage for a capacitor that supplies power to a load, The controller When a device temperature indicating a temperature of the in-vehicle device becomes equal to or higher than an upper limit threshold set higher than a guaranteed operating temperature of the in-vehicle device, the charging voltage is reduced to be lower than a normal voltage; When the device temperature becomes equal to or lower than a restoration threshold value set between the upper limit threshold value and the guaranteed operating temperature after the charging voltage has been reduced, the reduced charging voltage is restored to the normal voltage. In-vehicle device.

2. the recovery threshold is set to a value such that the recovery of the charging voltage to the normal voltage is completed before the device temperature reaches the guaranteed operating temperature; The in-vehicle device according to claim 1 .

3. The capacitor is an electric double layer capacitor. The in-vehicle device according to claim 1 .

4. The controller calculating a degree of decrease in the device temperature from the upper limit threshold to the guaranteed operating temperature; and setting the recovery threshold value according to the calculated degree of decrease so that the recovery of the charging voltage to the normal voltage is completed before the device temperature reaches the guaranteed operating temperature. The in-vehicle device according to claim 1 .

5. A control method for an in-vehicle device executed by a controller that controls a charging voltage for a capacitor that supplies power to a load, comprising: When a device temperature indicating a temperature of the in-vehicle device becomes equal to or higher than an upper limit threshold set higher than a guaranteed operating temperature of the in-vehicle device, the charging voltage is reduced to be lower than a normal voltage; When the device temperature becomes equal to or lower than a restoration threshold value set between the upper limit threshold value and the guaranteed operating temperature after the charging voltage has been reduced, the reduced charging voltage is restored to the normal voltage. A method for controlling an in-vehicle device.

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