Vehicle control device

Abstract

To suppress excessive restriction of passing electric power of a voltage conversion device.SOLUTION: A control device 20 controls a vehicle 10 including: an internal combustion engine 61; a voltage conversion device 30 converting voltage of electric power converted from power generated by the internal combustion engine 61; and a cooling device 31 cooling the voltage conversion device 30. When determining that a temperature of the voltage conversion device 30 increases to exceed a threshold temperature within a threshold time, the control device 20 controls an operation of the cooling device 31 to prevent the temperature of the voltage conversion device 30 from exceeding the threshold temperature, and prohibits idling stop of the internal combustion engine 61.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for controlling a vehicle. [Background technology]

[0002] As vehicles become more sophisticated and multifunctional, the types and number of electrical components mounted on the vehicle are increasing. In response to this background, an increasing number of vehicles are equipped with a high-voltage power supply system (e.g., a 48-volt power supply system) using a high-voltage battery (e.g., a lithium-ion battery) that charges the power generated by the alternator, and a low-voltage power supply system (e.g., a 12-volt power supply system) using a low-voltage battery (e.g., a lead-acid battery). The high-voltage power supply system supplies power to electrical components such as an actuator for an electric steering system and an air conditioner. The low-voltage power supply system supplies power to electrical components such as a headlight, a power window motor, a seat motor, a wiper motor, and a heater. A part of the power generated by the alternator is charged to the high-voltage battery, and the voltage of the remaining power is converted to a low voltage by a voltage conversion device and charged to the low-voltage battery. The voltage conversion device includes a plurality of switching elements, and the passing power of the voltage conversion device is limited so as not to exceed the breakdown temperature of the switching elements (see paragraph 0036 of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-230078 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the temperature of the voltage conversion device is high, limiting the passing power so as not to exceed the breakdown temperature of the switching element increases the discharge power from the low-voltage battery, which may shorten the life of the low-voltage battery.

[0005] Therefore, an object of the present invention is to propose a vehicle control device that solves such problems and suppresses excessive restrictions on the passing power of a voltage conversion device. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention relates to a vehicle control device, A control device for controlling a vehicle having an internal combustion engine, an alternator that converts the power generated by the internal combustion engine into DC power, a high-voltage battery that charges the DC power output from the alternator, a voltage conversion device that converts the voltage of the DC power output from the alternator to a low voltage, a low-voltage battery that charges the low-voltage DC power output from the voltage conversion device, and a cooling device that cools the voltage conversion device, the control device having a processor that executes computer-executable instructions, the computer-executable instructions including: determining whether the temperature of the voltage conversion device will rise above a threshold temperature within a threshold time; and, when it is determined that the temperature of the voltage conversion device will rise above the threshold temperature within the threshold time, controlling the operation of the cooling device so that the temperature of the voltage conversion device does not exceed the threshold temperature and prohibiting idling stop of the internal combustion engine.

[0007] In this way, when it is determined that the temperature of the voltage conversion device will rise above the threshold temperature within the threshold time, the operation of the cooling device is controlled so that the temperature of the voltage conversion device does not exceed the threshold temperature, thereby lengthening the time required for the temperature of the voltage conversion device to exceed the threshold temperature or suppressing the temperature of the voltage conversion device to below the threshold temperature. This makes it possible to suppress excessive restrictions on the passing power of the voltage conversion device caused by a rise in temperature of the voltage conversion device.

[0008] Furthermore, when it is determined that the temperature of the voltage conversion device will rise above the threshold temperature within the threshold time, the idling stop of the internal combustion engine is prohibited, so that the noise caused by the operation of the cooling device can be drowned out by the idling sound of the internal combustion engine. This makes it possible to reduce the discomfort of the noise caused by the operation of the cooling device, which operates with a high cooling capacity so that the temperature of the voltage conversion device does not exceed the threshold temperature. Effect of the Invention

[0009] According to the present invention, excessive restriction of the passing power of a voltage conversion device can be suppressed. [Brief description of the drawings]

[0010] [Figure 1] 1 is an explanatory diagram showing a schematic configuration of a vehicle according to an embodiment of the present invention; [Diagram 2] 4 is a flowchart showing a flow of a thermal protection process executed by a control device according to an embodiment of the present invention. [Diagram 3]4 is a flowchart showing a flow of an idling stop control process executed by a control device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Here, the same reference numerals denote the same components, and duplicated explanations will be omitted.

[0012] 1 is an explanatory diagram showing a schematic configuration of a vehicle 10 according to an embodiment of the present invention. The vehicle 10 includes a control device 20, a voltage conversion device 30, a cooling device 31, a sensor 32, a high-voltage battery 41, a low-voltage battery 42, a high-voltage load 51, a low-voltage load 52, an internal combustion engine 61, an alternator 62, an ignition switch 71, and a vehicle speed sensor 72.

[0013] The alternator 62 includes a rectifier circuit. The alternator 62 converts the power generated by the internal combustion engine 61 into AC power, and converts the AC power into DC power using the rectifier circuit.

[0014] The high-voltage battery 41 is charged with DC power output from the alternator 62. The high-voltage battery 41 is, for example, a 48-volt lithium-ion battery. The high-voltage battery 41 supplies power to a high-voltage load 51. The high-voltage load 51 is, for example, an electrical component such as an actuator for an electric steering system or an air conditioner.

[0015] The voltage conversion device 30 converts the voltage of the DC power output from the alternator 62 into a low voltage. The voltage conversion device 30 is, for example, a DC / DC converter including a plurality of switching elements (for example, insulated gate bipolar transistors).

[0016] The low-voltage battery 42 is charged with DC power output from the voltage conversion device 30. The low-voltage battery 42 is, for example, a 12-volt lead-acid battery. The low-voltage battery 42 supplies power to a low-voltage load 52. The low-voltage load 52 is, for example, an electrical component such as a headlight, a power window motor, a seat motor, a wiper motor, or a heater.

[0017] The cooling device 31 cools the voltage conversion device 30. The cooling device 31 is, for example, an air-cooling fan.

[0018] The sensor 32 is a sensor that measures a physical quantity serving as an index for estimating the temperature of the voltage conversion device 30. The sensor 32 may include, for example, a voltage sensor that measures an input voltage (high voltage) of the voltage conversion device 30, a voltage sensor that measures an output voltage (low voltage) of the voltage conversion device 30, and a current sensor that measures a current passing through the voltage conversion device 30. The sensor 32 may include, for example, a temperature sensor that measures the temperature of a switching element of the voltage conversion device 30.

[0019] The control device 20 receives a signal indicating the on / on state of the ignition switch 71, a vehicle speed signal (signal indicating the speed of the vehicle 10) output from a vehicle speed sensor 72, and a measurement signal (signal indicating a measurement result of a physical quantity serving as an index for estimating the temperature of the voltage conversion device 30) output from a sensor 32, and performs control of the voltage conversion device 30 (e.g., limiting passing power), operation control of the cooling device 31, idling stop control of the internal combustion engine 61, etc. The control device 20 is, for example, an electronic control unit equipped with an input / output interface, a processor, and a storage device.

[0020] FIG. 2 is a flowchart showing the flow of the thermal protection process executed by the control device 20.

[0021] In step 201, the control device 20 determines whether or not the ignition switch 71 is on. If the ignition switch 71 is on, the control device 20 proceeds to the process of step 202.

[0022] In step 202, the control device 20 judges whether the temperature difference between the maximum allowable temperature of the voltage conversion device 30 and the current temperature of the voltage conversion device 30 exceeds a threshold value TH1. The threshold value TH1 is set to, for example, a temperature value that is a guide for limiting the passing power of the voltage conversion device 30. The control device 20 estimates the current temperature of the voltage conversion device 30 based on the measurement signal output from the sensor 32. If the temperature difference between the maximum allowable temperature of the voltage conversion device 30 and the current temperature of the voltage conversion device 30 exceeds the threshold value TH1, the control device 20 judges that the temperature of the voltage conversion device 30 is at an appropriate temperature and therefore it is not necessary to limit the passing power of the voltage conversion device 30, and proceeds to the processing of step 203. On the other hand, if the temperature difference between the maximum allowable temperature of the voltage conversion device 30 and the current temperature of the voltage conversion device 30 is equal to or less than the threshold value TH1, the control device 20 judges that the temperature of the voltage conversion device 30 is at or above the appropriate temperature and therefore it is necessary to limit the passing power of the voltage conversion device 30, and proceeds to the processing of step 204.

[0023] In step 203, the control device 20 judges whether the temperature rise rate of the voltage conversion device 30 is lower than a threshold value TH2. The threshold value TH2 is set to a value that is a guideline for the temperature of the voltage conversion device 30 to rise beyond a threshold temperature (for example, the maximum allowable temperature of the voltage conversion device 30--threshold value TH1) within the threshold time. The control device 20 calculates the temperature rise rate of the voltage conversion device 30 based on the measurement signal output from the sensor 32. If the temperature rise rate of the voltage conversion device 30 is lower than the threshold value TH2, the control device 20 judges that the temperature of the voltage conversion device 30 will not exceed the threshold temperature within the threshold time, and proceeds to the process of step 205. On the other hand, if the temperature rise rate of the voltage conversion device 30 exceeds the threshold value TH2, the control device 20 judges that the temperature of the voltage conversion device 30 will exceed the threshold temperature within the threshold time, and proceeds to the process of step 207. The threshold temperature of the voltage conversion device 30 may be set to a different temperature value depending on the environmental temperature (ambient temperature around the vehicle 10).

[0024] In step 204, the control device 20 limits the passing power of the voltage conversion device 30 so as not to exceed the breakdown temperature of the switching element of the voltage conversion device 30. For example, when the passing power of the voltage conversion device 30 in normal operation is 15.3 volts / 150 amperes, the control device 20 may limit the passing power of the voltage conversion device 30 to 14.7 volts / 120 amperes. The passing power of the voltage conversion device 30 may be limited to a different value depending on the environmental temperature (ambient temperature around the vehicle 10). For example, when the environmental temperature is 35° C., the passing current of the voltage conversion device 30 may be limited to 60 amperes, and when the environmental temperature is 5° C., the passing current of the voltage conversion device 30 may be limited to 120 amperes.

[0025] In step 205, the control device 20 operates the voltage conversion device 30 without limiting the power passing through the voltage conversion device 30, and operates the cooling device 31 while maintaining the cooling capacity of the cooling device 31 at a normal state. For example, if the cooling device 31 is an air-cooled fan, the control device 20 may adjust the rotation speed of the air-cooled fan to an arbitrary rotation speed less than the maximum rotation speed.

[0026] In step 206, the control device 20 sets the thermal protection flag of the voltage conversion device 30 to OFF. The thermal protection flag is a flag for setting whether the idling stop function of the internal combustion engine 61 is enabled / disabled. When the thermal protection flag is set to OFF, the idling stop function of the internal combustion engine 61 is enabled. When the thermal protection flag is set to ON, the idling stop function of the internal combustion engine 61 is disabled.

[0027] In step 207, the control device 20 operates the voltage conversion device 30 without limiting the passing power of the voltage conversion device 30, and also operates the cooling device 31 so that the temperature of the voltage conversion device 30 does not exceed a threshold temperature. The control device 20 may, for example, operate the cooling device 31 so that the cooling capacity of the cooling device 31 is maximized. For example, if the cooling device 31 is an air-cooled fan, the control device 20 may adjust the rotation speed of the air-cooled fan to the maximum rotation speed. The control device 20 may also throttle the operating current of comfort devices mounted on the vehicle 10 (for example, the cooling capacity of the air conditioner may be reduced, or the volume of the audio may be reduced).

[0028] In step 208, the controller 20 sets the thermal protection flag of the voltage converter 30 to ON.

[0029] In step 209, the control device 20 determines whether or not the ignition switch 71 is off. If the ignition switch 71 is on, the control device 20 returns to the process of step 201. On the other hand, if the ignition switch 71 is off, the control device 20 ends the thermal protection process.

[0030] FIG. 3 is a flowchart showing the flow of the idling stop control process executed by the control device 20.

[0031] In step 301, the control device 20 determines whether or not the vehicle 10 has stopped. The control device 20 determines whether or not the vehicle 10 has stopped based on the vehicle speed signal output from the vehicle speed sensor 72, for example.

[0032] In step 302, the controller 20 determines whether the thermal protection flag is set to OFF.

[0033] If the thermal protection flag is set to OFF (if the idling stop function of the internal combustion engine 61 is enabled), in step 303, the control device 20 permits idling stop of the internal combustion engine 61.

[0034] If the thermal protection flag is set to ON (if the idling stop function of the internal combustion engine 61 is disabled), in step 304, the control device 20 prohibits idling stop of the internal combustion engine 61.

[0035] In step 305, the control device 20 determines whether the vehicle 10 has started from a stopped state or whether the ignition switch 71 has been switched from on to off. If the vehicle 10 has not started from a stopped state and the ignition switch 71 remains on, the control device 20 returns to the processing of step 301. On the other hand, if the vehicle 10 has started from a stopped state or the ignition switch 71 has been switched from on to off, the control device 20 ends the idling stop control processing.

[0036] Computer-executable instructions for causing the processor in the control device 20 to execute the thermal protection process (steps 201-209) and the idling stop control process (steps 301-305) are stored in a storage device in the control device 20. The processor in the control device 20 reads the computer-executable instructions from the storage device in the control device 20 and executes them to perform the thermal protection process (steps 201-209) and the idling stop control process (steps 301-305).

[0037] According to the embodiment of the present invention, when it is determined that the temperature of the voltage conversion device 30 will rise above the threshold temperature within the threshold time, the operation of the cooling device 31 is controlled so that the temperature of the voltage conversion device 30 does not exceed the threshold temperature, thereby lengthening the time required for the temperature of the voltage conversion device 30 to exceed the threshold temperature or suppressing the temperature of the voltage conversion device 30 to below the threshold temperature. This makes it possible to suppress excessive restriction of the passing power of the voltage conversion device 30 caused by a rise in temperature of the voltage conversion device 30.

[0038] Furthermore, even if it is determined that the temperature of the voltage conversion device 30 will rise above the threshold temperature within the threshold time, if the temperature of the voltage conversion device 30 is at an appropriate temperature, the voltage conversion device 30 can be operated without limiting the passing power of the voltage conversion device 30, thereby suppressing a decrease in the lifespan of the low-voltage battery 42 caused by an increase in the discharge power from the low-voltage battery 42 due to excessive limitation of the passing power of the voltage conversion device 30.

[0039] Furthermore, when it is determined that the temperature of the voltage conversion device 30 will rise above the threshold temperature within the threshold time, idling stop of the internal combustion engine 61 is prohibited, so that the noise caused by the operation of the cooling device 31 can be drowned out by the idling sound of the internal combustion engine 61. This makes it possible to reduce the discomfort of the noise caused by the operation of the cooling device 31, which operates with a high cooling capacity so that the temperature of the voltage conversion device 30 does not exceed the threshold temperature.

[0040] The embodiments of the present invention are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit of the present invention, and the present invention also includes equivalents thereof. Note that the same reference numerals indicate the same components, and duplicated explanations will be omitted.

[0041] Some or all of the above-described embodiments may be described as follows, but are not limited to the following: (Appendix 1) An internal combustion engine 61; An alternator 62 that converts the power generated by the internal combustion engine 61 into DC power; a high-voltage battery 41 that is charged with DC power output from an alternator 62; a voltage converter 30 that converts the voltage of the DC power output from the alternator 62 into a low voltage; a low-voltage battery 42 that is charged with the low-voltage DC power output from the voltage conversion device 30; A cooling device 31 that cools the voltage conversion device 30; A control device 20 for controlling a vehicle 10 including: A processor for executing computer-executable instructions; The computer executable instructions are determining whether the temperature of the voltage conversion device 30 rises above a threshold temperature within a threshold time (step 203); When it is determined that the temperature of the voltage conversion device 30 will rise above the threshold temperature within the threshold time (step 203; NO), the operation of the cooling device 31 is controlled so that the temperature of the voltage conversion device 30 does not exceed the threshold temperature (step 207), and idling stop of the internal combustion engine 61 is prohibited (steps 208, 304); A control device 20 including: (Appendix 2) The control device 20 according to claim 1, The cooling device 31 is a cooling fan. The computer executable instructions are When it is determined that the temperature of the voltage conversion device 30 will rise above the threshold temperature within the threshold time (step 203; NO), the rotation speed of the cooling fan is adjusted to the maximum rotation speed (step 207) so that the temperature of the voltage conversion device 30 does not exceed the threshold temperature; A control device 20 including: (Appendix 3) 3. The control device according to claim 1, The computer executable instructions are When the temperature difference between the maximum allowable temperature of the voltage conversion device 30 and the current temperature of the voltage conversion device 30 exceeds a threshold value TH1 (step 202; YES) and the temperature rise rate of the voltage conversion device 30 is higher than a threshold value TH2 (step 203; NO), it is determined that the temperature of the voltage conversion device 30 will rise above the threshold temperature within the threshold time; A control device 20 including: (Appendix 4) A control device 20 according to any one of claims 1 to 3, The computer executable instructions are When the temperature difference between the maximum allowable temperature of the voltage conversion device 30 and the current temperature of the voltage conversion device 30 is less than a threshold value TH1 (step 202; NO), limiting the passing power of the voltage conversion device 30 (step 204); A control device 20 including: [Explanation of symbols]

[0042] 10 vehicle 20 control device 30 voltage conversion device 31 cooling device 32 sensor 41 high voltage battery 42 low voltage battery 51 high voltage load 52 low voltage load 61 internal combustion engine 62 alternator 71 ignition switch 72 vehicle speed sensor

Claims

[Claim 1] An internal combustion engine, an alternator for converting the power generated by the internal combustion engine into DC power; a high-voltage battery that is charged with the DC power output from the alternator; a voltage converter for converting a voltage of the DC power output from the alternator into a low voltage; a low-voltage battery that is charged with the low-voltage DC power output from the voltage conversion device; a cooling device that cools the voltage conversion device; A control device for controlling a vehicle comprising: A processor for executing computer-executable instructions; The computer executable instructions are determining whether the temperature of the voltage conversion device rises above a threshold temperature within a threshold time; when it is determined that the temperature of the voltage conversion device will rise above a threshold temperature within a threshold time, controlling the operation of the cooling device so that the temperature of the voltage conversion device does not exceed the threshold temperature, and prohibiting idling stop of the internal combustion engine; A control device comprising:

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