Vehicle control device and overheat protection device

Abstract

To provide a vehicle control device which can intercept electric current which flows a conducting wire adequately when excess current is flowing.SOLUTION: A vehicle control device 1 comprises a current detection unit 3 which detects electric current flowing in a conducting wire and then outputs a current detection value, a current interruption unit 4 which intercepts the electric current flowing in the conducting wire and a computing unit 7 which calculates a temperature rise value due to Joule heat of the conducting wire by using the current detection value, estimates environmental temperature of environment around which the conducting wire is wired on the basis of the temperature rise value, outside air temperature information of a vehicle, inside air temperature information within a cabin and solar radiation information and determines whether or not output of interruption indication of the electric current to the current interruption part 4 is necessary on the basis of temperature of the conducting wire estimated by using the environmental temperature.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device and an overheat protection device. [Background technology]

[0002] Conventionally, electric and electronic devices use fuses that melt using Joule heat to prevent overheating due to excessive current. These fuses, which cut off the current by thermal melting, require labor to replace the fuse after it melts. Furthermore, it is necessary to select thick wire harnesses (conductors) in advance, taking into account variations in fuse melting characteristics. For this reason, using fuses increases the weight and cost of the wire harness.

[0003] Therefore, in recent years, a method has been used to realize overheat protection for conventional wire harnesses by using a semiconductor switch that uses a power semiconductor and temperature estimation technology for the wire harness.This method detects the value of the current flowing through the wire harness, uses this current value to calculate and estimate the temperature rise of the wire harness, and then shuts off the semiconductor switch to protect the wire harness.

[0004] In overheat protection using such a semiconductor switch, once the overcurrent is resolved, the semiconductor switch can be turned on to restore power supply, eliminating the need to replace parts such as fuses. Also, because there is no need to consider variations in melting, as with conventional fuses, thinner wire harnesses can be used, reducing weight and costs.

[0005] An overheat protection technology that uses such semiconductor switches and temperature estimation of a wire harness is described in Patent Document 1. Patent Document 1 states, "At predetermined time intervals, the current flowing through the wire is detected, the current current is used to estimate the current temperature of the wire, and the current temperature of the wire is compared with the upper limit temperature that the wire can tolerate. Even if the wire temperature rises due to a short circuit current that repeatedly turns on and off, this can be reliably detected and the current flowing through the wire can be cut off before the wire reaches the smoking temperature, thereby preventing the wire from smoking." [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-130944 Summary of the Invention [Problem to be solved by the invention]

[0007] A power supply wire harness in a vehicle's cabin may be routed in a shielded space partitioned between the vehicle's body material and the cabin interior lining. Examples of such shielded spaces include the cabin ceiling, the interior of a door panel, and the trunk. Wire harnesses for room lamps, electric roof motors, and the like are laid in the cabin ceiling. Wire harnesses for power window motors, electric door mirror motors, door lock actuators, and the like are laid inside the doors. In such shielded spaces, the environmental temperature of the environment in which the wire harnesses are installed becomes complex due to the influence of heat inflow due to solar radiation, the outside air temperature, and the inside air temperature of the cabin.

[0008] Conventionally, the temperature of a wiring harness is estimated by calculating the temperature rise due to self-heating of the wiring harness when current is flowing through it and adding this temperature rise to the reference temperature of the environment in which the wiring harness is installed. However, if there is an error in the reference temperature, the estimated temperature will be incorrect, and there is a possibility that the current will not be cut off at the appropriate temperature. If the estimated temperature of the wiring harness is higher than the actual temperature, the amount of current that can be supplied will decrease, resulting in a sudden current cut-off. Conversely, if the estimated temperature is lower than the actual temperature, the current will not be cut off appropriately even if the wiring harness becomes overheated.

[0009] One possible method for obtaining the reference temperature is to install a temperature sensor near the wire harness to be estimated. However, this method requires installing a temperature sensor for each of the many wire harnesses installed in the vehicle, which increases the cost of parts and the labor required to install the temperature sensors. In order to suppress such cost increases, a possible method is to set the reference temperature to information from temperature sensors of existing equipment installed in the vehicle.

[0010] However, wire harnesses installed inside the vehicle ceiling or doors are shielded by the interior lining, resulting in temperatures that differ from the temperature information of the vehicle interior. Furthermore, in environmental conditions with strong solar radiation, the temperature rise caused by solar radiation makes the environmental temperature even more different from the temperature inside the vehicle interior and the outside air temperature, increasing the error in the estimated temperature of the wire harness. Therefore, it is necessary to appropriately estimate the environmental temperature of the environment in which the wire harness is installed, which serves as the basis for estimating the temperature of the wire harness.

[0011] The present invention has been made in view of the above circumstances, and has an object to make it possible to appropriately estimate the temperature of a conductor. [Means for solving the problem]

[0012] The vehicle control device according to the present invention includes a current detection unit that detects a current flowing in a conductor and outputs a current detection value, a current interruption unit that interrupts the current flowing in the conductor, and a current detection unit that calculates a temperature rise value due to Joule heat in the conductor using the current detection value and outputs the temperature rise value and the temperature of the vehicle. Temperature information of the outside air environment Outside temperature information and the inside of the vehicle Temperature information of the indoor air environment Based on indoor temperature information and solar radiation information 、 The wires are routed The environment is a shielded space, and between the outside air environment of the vehicle and the inside air environment of the vehicle, there is a space that is thermally shielded from the outside air environment and the inside air environment. The ambient temperature of the environment , the temperature rise value based on solar radiation information is added to the weighted average of the indoor temperature information and the outdoor temperature information. Estimate, The temperature of the conductor is estimated by adding the environmental temperature in the shielded space to the temperature rise value; The device further includes a calculation unit that determines whether or not it is necessary to output a current interruption instruction to the current interruption unit based on the estimated temperature of the conductor. [Effects of the Invention]

[0013] According to the present invention, the temperature of the conductor can be appropriately estimated, and therefore, when an overcurrent occurs, the current flowing through the conductor can be appropriately interrupted. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing an example of a basic configuration of an overheat protection system for a wire harness according to a first embodiment of the present invention. [Figure 2] 1 is a block diagram showing an example of the hardware configuration of a computer according to a first embodiment of the present invention. [Figure 3] 1 is a diagram showing an example in which the overheat protection system according to the first embodiment of the present invention is applied to a wire harness installed on the ceiling of a vehicle. [Figure 4] 1 is a diagram showing a schematic configuration of a ceiling space in which a wire harness according to a first embodiment of the present invention is installed. [Figure 5] FIG. 2 is a diagram showing the heat inflow into the shielded space according to the first embodiment of the present invention using an equivalent thermal circuit network. [Figure 6] FIG. 2 is a block diagram of an estimation calculation in an environmental temperature estimation unit using model formula (1) according to the first embodiment of the present invention. [Figure 7]1 is a cross-sectional view of a wire harness according to a first embodiment of the present invention. [Figure 8] 1 is a circuit diagram showing a heat dissipation model of a wire harness according to a first embodiment of the present invention, expressed as an equivalent thermal circuit network. [Figure 9] FIG. 2 is a block diagram in which an equivalent thermal circuit network according to the first embodiment of the present invention is converted into a transfer function. [Figure 10] FIG. 10 is a block diagram showing an example of processing by an environmental temperature estimation unit according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functions or configurations are designated by the same reference numerals, and redundant description will be omitted.

[0016] [First embodiment] 1 is a diagram showing an example of the basic configuration of an overheat protection system 1 for a wire harness 5. The overheat protection system 1 is an example of a vehicle control device to which the present invention is applied.

[0017] The overheat protection system 1 controls the current I supplied to the load device 6 through the wire harness 5 . The wire harness 5 is arranged along a shielded space 23 between the pillar and the ceiling of a vehicle 20 shown in FIG. 3, which will be described later.

[0018] The load device 6 is an actuator that operates the vehicle 20 through a motor, a solenoid, etc. Electric power for the load device 6 is supplied from a battery 2 mounted on the vehicle 20. A current detection element 3, a breaker element 4, and a wire harness 5 are connected to a power supply path between the battery 2 and the load device 6. The current detection element 3 detects the current value of a current I flowing through the wire harness 5.

[0019] The current detection unit (current detection element 3) detects the current flowing through the conductor (wire harness 5) and outputs the detected current value. This current detection element 3 has a shunt resistor connected in series to the power supply path, and can detect the current I from the voltage drop across the shunt resistor. The current detection element 3 can also detect the current I by using a current sense power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) as the interrupter element 4.

[0020] The current interruption unit (interruption element 4) interrupts the current flowing through the conductor (wire harness 5). This interruption element 4 is a semiconductor switch such as a power MOSFET, and has the function of interrupting the power supply to the load device 6 via the wire harness 5.

[0021] The overheat protection system 1 includes a computing unit 7 . The calculation unit (calculator 7) calculates a temperature rise value of the conductor (wire harness 5) due to Joule heat using the current detection value. Then, the calculation unit (calculator 7) estimates an environmental temperature Ta of the environment in which the conductor (wire harness 5) is wired based on the temperature rise value, outside air temperature information 12a of the vehicle 20, inside air temperature information 11a in the vehicle cabin, and solar radiation information 13a. Furthermore, the calculation unit (calculator 7) determines whether or not to output a current interruption command to the current interruption unit (interruption element 4) based on the temperature of the conductor (wire harness 5) estimated using the environmental temperature Ta. This calculator 7 is used as an overheat protection device that protects the wire harness 5 from overheating. This calculator 7 includes a conductor temperature estimation unit 8, an interruption determination unit 9, and an environmental temperature estimation unit 10.

[0022] As the computing unit 7, a microcomputer, a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), etc. can be used. The computing unit 7 estimates an environmental temperature Ta in the installation environment of the wire harness 5, and estimates the temperature of the wire harness 5 based on the environmental temperature Ta and Joule heat generated in the wire harness 5. Then, the computing unit 7 determines whether to cut off the power supply to the load device 6 through the wire harness 5.

[0023] The calculation unit (calculator 7) estimates the temperature of the conductor (wire harness 5) by adding the environmental temperature Ta in the shielded space (shielded space 23) to the temperature rise value. For example, the conductor temperature estimation unit 8 finds the temperature rise value from the current information input from the current detection element 3, and adds the estimated value of the environmental temperature Ta of the environment in which the wire harness 5 is installed to the temperature rise value to calculate and estimate the temperature of the wire harness 5. In the calculation to estimate the temperature of the wire harness 5, the heat generation amount and heat dissipation characteristic model of the wire harness 5 to be estimated are used. A specific example of a method for estimating the temperature of the wire harness 5 will be described later.

[0024] The interruption determination unit 9 determines that the current is interrupted when the temperature estimated by the conductor temperature estimation unit 8 becomes higher than a predetermined threshold, and outputs an interruption signal to the interrupting element 4. The interrupting element 4 interrupts the current I flowing through the wire harness 5 based on the interruption instruction from the interruption determination unit 9.

[0025] The environmental temperature estimation unit 10 estimates the environmental temperature Ta of the environment in which the wire harness 5 is installed based on inside air temperature information 11a, outside air temperature information 12a, and solar radiation information 13a of the vehicle 20. The environmental temperature Ta estimated by the environmental temperature estimation unit 10 is output to the conductor temperature estimation unit 8. Here, the calculation unit (environmental temperature estimation unit 10) acquires outside air temperature information 12a from an outside air temperature detection unit (outside air temperature sensor 12) installed in the vehicle 20, acquires inside air temperature information 11a from an inside air temperature detection unit (inside air temperature sensor 11) installed in the vehicle 20, and acquires solar radiation information 13a from a solar radiation detection unit (solar radiation sensor 13) installed in the vehicle 20.

[0026] The inside air temperature information 11a can be acquired from an inside air temperature sensor 11 that detects the temperature inside the vehicle cabin. The inside air temperature sensor 11 is installed in a location that is shielded from sunlight, such as inside the instrument panel inside the vehicle cabin. For example, a thermistor used to control an air conditioner can be used as the inside air temperature sensor 11.

[0027] The outside air temperature information 12a can be acquired from an outside air temperature sensor 12 mounted on the vehicle 20. The outside air temperature sensor 12 is preferably installed in a location that is not affected by a heat source of the vehicle 20, such as a thermistor for engine control installed in the front of the vehicle 20.

[0028] The solar radiation information 13a can be acquired, for example, from a solar radiation sensor 13 for controlling an air conditioner. The solar radiation sensor 13 is installed on the dashboard at the front of the vehicle and detects solar radiation entering through the windshield using a photodiode. Another example of the solar radiation sensor 13 is a sensor used in an automatic headlight.

[0029] The solar radiation information 13a can also be acquired from brightness information of a front camera, a side camera, or a rearview camera for driving assistance mounted on the vehicle 20. Such solar radiation information can be acquired via an in-vehicle network such as a CAN (Controller Area Network).

[0030] Next, the hardware configuration of the computer 50 that constitutes the overheat protection system 1 will be described. Fig. 2 is a block diagram showing an example of the hardware configuration of a calculator 50. The calculator 50 is an example of hardware used as a computer that can operate as the overheat protection system 1 according to this embodiment. The overheat protection system 1 according to this embodiment realizes an environmental temperature estimation method in which the functional blocks shown in Fig. 2 work together as a result of the calculator 50 (computer) executing a program. Note that the above-mentioned microcomputer, DSP, or FPGA may also be used as the calculator 50.

[0031] The computer 50 includes a CPU (Central Processing Unit) 51, a ROM (Read Only Memory) 52, and a RAM (Random Access Memory) 53, each connected to a bus 54. The computer 50 further includes a non-volatile storage 55 and a network interface 56.

[0032] The CPU 51 reads out program code of software that realizes each function according to this embodiment from the ROM 52, loads it into the RAM 53, and executes it. Variables, parameters, etc. that are generated during the calculation processing of the CPU 51 are temporarily written to the RAM 53, and these variables, parameters, etc. are read out as appropriate by the CPU 51. However, an MPU (Micro Processing Unit) may be used instead of the CPU 51.

[0033] The nonvolatile storage 55 may be, for example, a hard disk drive (HDD), a solid state drive (SSD), a flexible disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, or a nonvolatile memory. In addition to an operating system (OS) and various parameters, programs for operating the computer 50 are recorded in the nonvolatile storage 55. The ROM 52 and the nonvolatile storage 55 record programs, data, and the like necessary for the CPU 51 to operate, and are used as an example of a computer-readable non-transitory storage medium that stores a program executed by the computer 50.

[0034] The network interface 56 may be, for example, a network interface card (NIC), and various data can be transmitted and received between devices via a CAN, dedicated line, or the like connected to a terminal of the NIC.

[0035] Fig. 3 is a diagram showing an example in which the overheat protection system 1 according to this embodiment is applied to a wire harness 5 laid on the ceiling of a vehicle 20. Fig. 3 is a cross-sectional view of the vehicle 20 as seen from the side.

[0036] An example of the load device 6 is a room lamp installed on the ceiling of the vehicle interior. Power is supplied from a battery 2 installed in the front of the vehicle 20 to a power distribution unit 14 (an example of an on-board power distribution device) installed in the vehicle interior. The load device 6 is then driven by the power supplied from the power distribution unit 14 via a wire harness 5. This power distribution unit 14 is configured as the overheat protection system 1 shown in FIG. 1. In this way, the overheat protection system 1 and the overheat protection device can also be applied to the current supply path of an on-board power distribution device that distributes power supplied from the battery 2 to various parts within the vehicle 20. Therefore, the power distribution unit 14 can aggregate various information detected by each sensor, estimate the temperature of the wire harness 5 in each zone of the vehicle 20, and cut off power sharing to the load device 6 as necessary.

[0037] The wire harness 5 passes through the pillars and ceiling of the vehicle 20 and is connected to the load device 6 and the power distribution unit 14. The wire harness 5 is laid in the space between the body 21 of the vehicle 20 and the interior lining 22 of the vehicle compartment. The body 21 is the portion of the vehicle 20 that is exposed to sunlight, such as the pillars, ceiling, and doors. The current detection element 3, the interrupting element 4, and the computing unit 7 are provided in the power distribution unit 14. The power distribution unit 14 estimates the temperature of the wire harness 5 that passes through the ceiling of the vehicle 20, and protects the wire harness from overheating.

[0038] Between the outside air environment and the inside air environment of the vehicle 20, a shielded space 23 is formed which is thermally shielded from the outside air environment and the inside air environment and in which the conductors are wired. The environment in which the conductors (wire harness 5) are wired is the shielded space (shielded space 23) in which the conductors (wire harness 5) are wired. The wire harness 5 is disposed in the shielded space 23 in the ceiling which is shielded from the interior and exterior of the vehicle. For this reason, the wire harness 5 is placed in an environment in which the environmental temperature changes due to heat from solar radiation in addition to the outside air temperature and inside air temperature of the vehicle 20.

[0039] The environmental temperature estimation unit 10 according to this embodiment acquires outside air temperature information 12a from an outside air temperature sensor 12 installed at the front of the vehicle 20. The environmental temperature estimation unit 10 also acquires inside air temperature information 11a from an inside air temperature sensor 11 installed inside the vehicle cabin. The environmental temperature estimation unit 10 also acquires solar radiation information 13a from a solar radiation sensor 13 installed inside the instrument panel inside the vehicle cabin. Based on these three pieces of information, the environmental temperature estimation unit 10 estimates the environmental temperature Ta in the shielded space 23 in which the wire harness 5 is installed.

[0040] FIG. 4 is a diagram showing a schematic configuration of the shielded space 23 in which the wire harness 5 is installed.

[0041] As described above, a shielded space (shielded space 23) is formed between the outside air environment of the vehicle 20 and the inside air environment of the vehicle 20. The shielded space 23 is thermally shielded from the outside air environment and the inside air environment, and the conductor (wire harness 5) is wired therein. The wire harness 5 is laid in the shielded space 23, which is shielded by the body 21 of the vehicle 20 and the interior lining 22 of the vehicle cabin. The outside of the body 21 is the outside air environment, and the inside of the lining 22 is the inside air environment. The outside air temperature information 12a is temperature information of the outside air environment, and the inside air temperature information 11a is temperature information of the inside air environment. The environmental temperature estimation unit 10 shown in FIG. 1 estimates the environmental temperature Ta of the shielded space 23 using the inside air temperature information 11a, the outside air temperature information 12a, and the solar radiation information 13a.

[0042] 5 is a diagram showing, by an equivalent thermal circuit network, the heat inflow into the shielded space 23. In FIG. 5, the principle by which the environmental temperature estimating unit 10 estimates the environmental temperature Ta of the shielded space 23 is shown.

[0043] 5, the outside air temperature of the outside environment is represented by a voltage source Tout, the inside air temperature of the outside environment is represented by a voltage source Tin, the shielded space 23 is represented by a heat capacity C, and the heat inflow Qs due to solar radiation is represented by a current source. The environmental temperature estimation unit 10 estimates the environmental temperature of the shielded space (shielded space 23) by adding a temperature rise value based on solar radiation information 13a to the weighted average of the inside air temperature information 11a and the outside air temperature information 12a.

[0044] Heat is conducted from the outside of the vehicle compartment to the heat capacity C of the shielded space 23 from the outside air temperature Tout via the thermal resistance R1 of the body 21 of the vehicle 20. Heat is also conducted from the inside of the vehicle compartment to the heat capacity C via the thermal resistance R2 of the interior lining 22. Heat inflow Qs due to solar radiation flows into the shielded space 23. The temperature Ta of the shielded space 23 can be obtained in a steady state by the following equation (1) (also called model equation (1)). Note that in the steady state, the heat capacity C of the shielded space 23 is considered to be open, i.e., non-existent, and therefore the heat capacity C is not included in equation (1).

[0045]

number

[0046] Equation (1) shows that the environmental temperature estimation unit 10 can estimate the environmental temperature Ta by adding the temperature rise due to the heat inflow Qs caused by solar radiation to the weighted average value of the outside air temperature Tout and the inside air temperature Tin according to the thermal resistances R1 and R2.

[0047] FIG. 6 shows a block diagram of the estimation calculation in the environmental temperature estimation unit 10 using the above model formula (1).

[0048] The environmental temperature estimation unit 10 includes a first term calculation unit 31 and a second term calculation unit 32 of the model formula (1). The first term calculation unit 31 calculates the first term of the equation (1) using the inside air temperature information 11a (Tin) and the outside air temperature information 12a (Tout) as input. The second term calculation unit 32 calculates the second term of the equation (1) using the heat inflow Qs due to solar radiation, the thermal resistance R1 of the body 21 of the vehicle 20, and the thermal resistance R2 of the interior lining 22 as input. Then, the environmental temperature estimation unit 10 adds up the calculation result of the first term calculation unit 31 and the calculation result of the second term calculation unit 32 to estimate the environmental temperature Ta, and outputs this environmental temperature Ta to the conductor temperature estimation unit 8.

[0049] More preferably, by setting the thermal resistance R1 based on the thermal conductivity corresponding to the body material and thickness of the vehicle 20, it is possible to improve the accuracy of the environmental temperature Ta estimated by the environmental temperature estimation unit 10. Therefore, the calculation unit (environmental temperature estimation unit 10) sets a weighted average of the thermal resistances R1 and R2 of the outside air temperature Tout and the inside air temperature Tin according to the material of the body material of the vehicle 20 that shields the shielded space (shielded space 23) from the outside air environment and the material of the lining material that shields the shielded space (shielded space 23) from the inside air environment. For example, by setting the thermal resistances R1 and R2 based on the thermal conductivity corresponding to the material and structure of the interior lining 22 in the vehicle compartment, it is possible to improve the accuracy of the environmental temperature Ta estimated by the environmental temperature estimation unit 10.

[0050] Furthermore, the calculation unit (environmental temperature estimation unit 10) sets a coefficient for the solar radiation information 13a according to the emissivity of the body material of the vehicle 20 that shields the outside air environment and the shielded space (shielded space 23). For example, by setting a coefficient k for the heat inflow Qs obtained from the solar radiation information 13a in the above formula (1) and setting the coefficient k based on the emissivity according to the material and color of the body 21, it is possible to improve the accuracy of the environmental temperature Ta estimated by the environmental temperature estimation unit 10. Note that the thermal resistances R1, R2 and the coefficient k are set in advance for each vehicle model when the automobile is manufactured.

[0051] In this embodiment, the method in which the environmental temperature estimation unit 10 calculates the environmental temperature Ta using Equation (1) has been described. However, the environmental temperature estimation unit 10 may use a method in which a table or map data indicating the relationship between the inside air temperature information 11a (Tin), the outside air temperature information 12a (Tout), and the solar radiation information 13a (Qs) is prepared in advance, and the environmental temperature Ta is calculated based on this information.

[0052] Next, an example of a method for estimating the temperature rise value due to Joule heat caused by the current I flowing through the wire harness 5 in the conductor temperature estimator 8 will be described. Fig. 7 is a cross-sectional view of the wire harness 5. In Fig. 7, the heat dissipation path of the wire harness 5 is shown.

[0053] The wire harness 5 is composed of a conductor portion 41 made of a conductor through which a current I flows, and an insulating portion 42 that covers the conductor portion 41. When the current I flows through the conductor portion 41, heat Pw is generated by Joule heat due to the electrical resistance of the conductor. The heat Pw is accumulated in the heat capacity C1 of the conductor and is simultaneously thermally conducted to the insulating portion 42.

[0054] In the insulating portion 42, heat is accumulated in the heat capacity C2 of the insulating portion 42 and is simultaneously conducted to the surface of the insulating portion 42 via the thermal resistance R2 of the insulating portion 42. The heat is then dissipated from the surface of the insulating portion 42 into the air surrounding the wire harness 5. The heat dissipation into the air surrounding the wire harness 5 is determined by the thermal resistance R3, which is determined by the heat transfer coefficient and radiant heat.

[0055] FIG. 8 is a circuit diagram showing a heat dissipation model of the wire harness 5 as an equivalent thermal circuit network.

[0056] 8, the heat of the heat generation Pw is accumulated in the thermal capacity C1 of the conductor, and then accumulated in the thermal capacity C2 of the insulating portion 42 via the thermal resistance R2 of the insulating portion 42. Then, after the heat is accumulated in the thermal capacity C2 of the insulating portion 42, it is dissipated to the air surrounding the wire harness 5 via the thermal resistance R3.

[0057] Figure 9 is a block diagram of the equivalent thermal network converted into a transfer function. In this transfer function, the input is the heat generation amount Pw and the output is the conductor temperature Tc.

[0058] The conductor temperature Tc of the wire harness 5 is estimated based on the transfer function shown in Fig. 9. The environmental temperature Ta in Fig. 9 is the temperature Ta of the shielded space 23 in which the above-mentioned wire harness 5 is installed. The temperature Tc of the wire harness 5 can be estimated by adding the temperature increase value ΔTc due to Joule heat of the wire harness 5 based on the detected current value detected by the current detection element 3 to the temperature Ta of the shielded space 23.

[0059] The calculator 7 of the overheat protection system 1 according to the first embodiment described above can estimate the temperature of the wire harness 5 based on the outside air temperature Tout of the vehicle 20, the inside air temperature Tin of the vehicle cabin, and the solar radiation information 13a (Qs). Therefore, the environmental temperature Ta of the shielded space 23, which is affected by solar radiation, can be estimated without adding a new temperature sensor to the shielded space 23 in which the wire harness 5 is installed. For example, in a conventional system where five wire harnesses 5 are wired on the ceiling of the vehicle 20, a temperature sensor is provided for each wire harness 5. In contrast, in the present embodiment, the wire harnesses 5 share a common wiring environment. Therefore, the calculator 7 can estimate the temperature of each wire harness 5 simply by estimating the environmental temperature Ta at a single location. Since the environmental temperature estimation unit 10 appropriately estimates the environmental temperature Ta in this manner, the estimated temperature of the wire harness does not have an error compared to the actual temperature.

[0060] Furthermore, the environmental temperature estimation unit 10 acquires the environmental temperature Ta used to estimate the temperature of each wire harness 5 at low cost and with high accuracy, thereby improving the accuracy of temperature estimation of the wire harness 5. Because the conductor temperature estimation unit 8 can appropriately estimate the temperature of the wire harness 5, the cutoff determination unit 9 can appropriately cut off the current flowing through the wire harness 5 when an overcurrent occurs. This makes it possible to reliably detect an overtemperature of the wire harness 5 and cut off the overcurrent to the load device 6 without excessively limiting the amount of current that the battery 2 can supply to the load device 6. Furthermore, because the accuracy of temperature estimation of the wire harness 5 is improved, it becomes possible to relax the design margin and design the wire harness 5 to be thinner. This makes it possible to reduce the weight and cost of the wire harness 5 wired in the vehicle 20.

[0061] The overheat protection system 1 according to this embodiment can replace conventional protection circuits that use fuses or relays. Moreover, the overheat protection system 1 can monitor the temperature of the wire harness 5, which makes it possible to distribute the current load of the power network that supplies current to each component.

[0062] In the above-described embodiment, an example has been described in which the present invention is applied to temperature estimation of the wire harness 5 of a room lamp installed on the ceiling of the vehicle interior, but the present invention is not limited to this. For example, the present invention can be applied to a wire harness 5 that supplies power to a load device such as a map lamp, a digital room mirror, an electric roof, a patrol lamp, a LiDAR (Light Detection and Ranging) for recognizing the outside world, or a camera, which are installed on the ceiling of the vehicle interior. In addition, the present invention can be applied to a wire harness 5 that transmits power, such as a solar panel installed on the top surface of the vehicle 20.

[0063] Furthermore, since the inside of the door panels and the inside of the side surfaces of the body 21 in the vehicle interior are also shaded spaces 23 that are affected by solar radiation, the present invention can also be applied to the wire harness 5 laid in this shaded space 23. The shaded space 23 may also be provided, for example, near the brakes. Examples of load devices 6 used in such places include power windows, power door mirrors, side cameras, door lock actuators, turn signal lamps, stop lamps, rear wiper actuators, and license plate lamps. The present invention can also be applied to the wire harness 5 for supplying power to these load devices 6. The present invention can also be applied to estimating the temperature in a trunk space separated from the vehicle interior.

[0064] Furthermore, the calculator 7 may compare the temperature of the wire harness 5 estimated by the method according to the present embodiment with the temperature acquired from a temperature sensor already installed in the wire harness 5. If the estimated temperature of the wire harness 5 deviates from the temperature acquired from the temperature sensor already installed in the wire harness 5, it is possible to investigate whether there is a malfunction or the like in each sensor in the vehicle 20.

[0065] Furthermore, the calculator 7 may acquire the inside air temperature information 11a from a sensor other than the inside air temperature sensor 11. Similarly, the calculator 7 may acquire the outside air temperature information 12a from a sensor other than the outside air temperature sensor 12, and may acquire the solar radiation information 13a from a sensor other than the solar radiation sensor 13.

[0066] Moreover, the overheat protection system 1 and the overheat protection device according to the present embodiment can be applied to a path through which an on-board ECU (engine ECU (Electronic Control Unit), zone ECU) supplies current to an actuator (motor, etc.), fuse, relay box, etc. The overheat protection system 1 and the overheat protection device may be mounted on the on-board ECU or zone ECU.

[0067] The overheat protection system 1 and overheat protection device according to the present embodiment may also be applied to an integrated ECU mounted on a vehicle. In this case, the integrated ECU may aggregate information detected by each sensor to estimate the temperature of the shielded space and the wire harness 5 in each area of ​​the vehicle, and transmit the estimated temperature information to the power distribution device. As a result, the power distribution device can take measures such as reducing the power supplied to an area where a wire harness 5 with a temperature higher than a reference value is installed by receiving the temperature information.

[0068] [Second embodiment] Next, a configuration example of an overheat protection system 1 according to a second embodiment of the present invention will be described. In the first embodiment described above, an example was shown in which the inside air temperature information 11a, outside air temperature information 12a, and solar radiation information 13a in the environmental temperature estimation unit 10 are acquired from sensors mounted on the vehicle 20 via an in-vehicle network, but this is not limited to this in the implementation of the present invention. In the overheat protection system 1 according to the second embodiment, weather information and date and time information can be acquired from outside the vehicle 20 via a wireless network such as a mobile phone network, and this information can be used to set the outside air temperature information and solar radiation information.

[0069] 10 is a block diagram showing an example of processing by an environmental temperature estimation unit 10A according to the second embodiment. Here, an example of processing for estimating the environmental temperature of the wire harness 5 using information acquired from outside the vehicle 20 via a wireless network will be described.

[0070] The environmental temperature estimation unit 10A estimates the environmental temperature of the shielded space 23 in which the wire harness 5 is installed using the inside air temperature information 11a, the weather information 15, the GPS information 16a, and the date and time information 17a. For this reason, the environmental temperature estimation unit 10A includes an outside air temperature calculation unit 33 and a solar radiation amount calculation unit 34 in addition to the first term calculation unit 31 and the second term calculation unit 32 of the model formula (1). This calculation unit (environmental temperature estimation unit 10A) determines the current position of the vehicle 20 based on GPS information 16a received from a GPS information receiving unit (GPS device 16), obtains weather information 15 for the current position from a wireless communication unit (wireless communication device 18) using the date and time information 17a, and calculates outside air temperature information 12a and solar radiation information 13a based on the weather information 15.

[0071] The environmental temperature estimation unit 10A acquires inside air temperature information 11a from an inside air temperature sensor 11 in the passenger compartment of the vehicle 20. The inside air temperature sensor 11 is installed in a location shielded from sunlight, such as inside an instrument panel in the passenger compartment, and may be, for example, a thermistor used to control an air conditioner.

[0072] The environmental temperature estimation unit 10A also acquires weather information 15 by receiving radio waves from a mobile phone base station or the like using a wireless communication device 18 installed in the vehicle 20. The weather information 15 includes at least information on the weather and temperature for each region.

[0073] Furthermore, the environmental temperature estimation unit 10A acquires GPS information 16a from a GPS device 16 included in a navigation system (not shown) mounted on the vehicle 20. The GPS information 16a is location information indicating the current location of the vehicle 20. The GPS information 16a is used to identify the location where the vehicle 20 is traveling. The GPS information 16a is input to an outside air temperature calculation unit 33 and a solar radiation amount calculation unit 34.

[0074] The date and time information 17a is information about the date and time when the vehicle 20 is traveling. The date and time information 17a makes it possible to determine whether the vehicle 20 is traveling during the day or night. The environmental temperature estimation unit 10A acquires the date and time information 17a from the clock 17 installed in the vehicle 20, and can also acquire the date and time information 17a by receiving radio waves carrying time information from an external source.

[0075] The outside air temperature calculation unit 33 has a function of calculating the outside air temperature. Weather information 15 is input to the outside air temperature calculation unit 33 via the wireless communication device 18. GPS information 16a is also input to the outside air temperature calculation unit 33 from the GPS device 16, and date and time information 17a is also input to the outside air temperature calculation unit 33. The outside air temperature calculation unit 33 selects weather information 15 for the area including the current location of the vehicle 20 based on the GPS information 16a. The outside air temperature calculation unit 33 also selects weather information 15 for the current time in the area based on the date and time information 17a. The outside air temperature calculation unit 33 then calculates the outside air temperature of the vehicle 20 based on the weather information 15, the GPS information 16a, and the date and time information 17a, and outputs the calculated outside air temperature Tout to the first term calculation unit 31.

[0076] The solar radiation amount calculation unit 34 has a function of calculating the amount of solar radiation. The amount of solar radiation calculated by the solar radiation amount calculation unit 34 is found as the heat inflow Qs due to solar radiation shown in the above formula (1). Weather information 15 is input to the solar radiation amount calculation unit 34 via the wireless communication device 18. GPS information 16a and date and time information 17a are also input to the solar radiation amount calculation unit 34. The solar radiation amount calculation unit 34 selects weather information 15 for the area including the location where the vehicle 20 is traveling based on the GPS information 16a. The outside air temperature calculation unit 33 selects weather information 15 for the current time in the area based on the date and time information 17a. The outside air temperature calculation unit 33 then calculates the amount of solar radiation based on the weather information 15, the GPS information 16a, and the date and time information 17a, and outputs the calculated amount of solar radiation to the second term calculation unit 32 as the heat inflow Qs due to solar radiation.

[0077] The first term calculation unit 31 calculates the first term of the equation (1) using the inside air temperature information 11a (Tin) and the outside air temperature information 12a (Tout) from the outside air temperature calculation unit 33 as inputs. The second term calculation unit 32 calculates the second term of the equation (1) using the heat inflow Qs due to solar radiation, the thermal resistance R1 of the body 21 of the vehicle 20, and the thermal resistance R2 of the interior lining 22 as input.

[0078] Then, the environmental temperature estimation unit 10A adds up the calculation result of the first term calculation unit 31 and the calculation result of the second term calculation unit 32 to estimate the environmental temperature Ta, and outputs this environmental temperature Ta to the conductor temperature estimation unit 8. Thereafter, the conductor temperature estimation unit 8 calculates and estimates the temperature of the wire harness 5 based on the estimated value of the environmental temperature Ta, and the interruption determination unit 9 determines that an interruption has occurred if the temperature estimated value from the conductor temperature estimation unit 8 is higher than a predetermined threshold, and outputs an interruption signal to the interrupting element 4.

[0079] The environmental temperature estimator 10A according to the second embodiment described above compares the weather information 15, GPS information 16a, and date and time information 17a to calculate the outside air temperature Tout and the amount of solar radiation Qs at which the vehicle 20 is traveling. The environmental temperature estimator 10A then calculates a weighted average of the calculated outside air temperature Tout and inside air temperature information 11a (Tin) using weights according to the thermal resistances R1 and R2. The environmental temperature estimator 10A also calculates the temperature rise due to the calculated heat inflow Qs caused by solar radiation. The environmental temperature estimator 10A can estimate the environmental temperature Ta by adding up the results of these calculations.

[0080] The environmental temperature estimation unit 10A shown in FIG. 10 does not require the vehicle 20 to be equipped with a solar radiation sensor 13 for acquiring solar radiation information 13a, and can estimate the environmental temperature Ta even in a vehicle 20 that does not have a solar radiation sensor 13.

[0081] Although the environmental temperature estimation unit 10A has been configured to acquire outside air temperature information from weather information, it may also be configured to use an outside air temperature sensor 12 mounted on the vehicle 20. For example, it may be configured to appropriately combine a method of acquiring outside air temperature information 12a from the outside air temperature sensor 12 mounted on the vehicle 20 shown in Fig. 1 via an in-vehicle network with a method of acquiring outside air temperature information 12a via an external network shown in Fig. 10. The combination method can be appropriately selected depending on whether or not a sensor is mounted on the vehicle 20 and the temperature estimation accuracy of the wire harness 5.

[0082] Furthermore, when the outside air temperature calculation unit 33 calculates the outside air temperature, it is also possible to change the temperature to be added to the outside air temperature depending on, for example, whether the vehicle 20 is in a shady parking lot or is traveling on a road. If the vehicle 20 is traveling, the calculation may add a few degrees to the average temperature in the shady parking lot obtained from the weather information 15 to calculate the outside air temperature. By calculating the outside air temperature higher in this way, the current in the wire harness 5 can be safely interrupted even if a temperature higher than the actual temperature of the wire harness 5 is estimated.

[0083] It should be noted that the present invention is not limited to the above-described embodiments, and various other applications and modifications are possible without departing from the gist of the present invention as set forth in the claims. For example, the above-described embodiments have described the configuration of the device and system in detail and specifically in order to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of the embodiments described here with the configuration of other embodiments, and it is also possible to add the configuration of one embodiment to the configuration of another embodiment. Furthermore, it is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations. In addition, the control lines and information lines shown are those that are considered necessary for the explanation, and do not necessarily show all the control lines and information lines in the product. In reality, it can be assumed that almost all components are interconnected. [Explanation of symbols]

[0084] 1...Overheat protection system, 2...Battery, 3...Current detection element, 4...Breakdown element, 5...Wire harness, 6...Load device, 7...Calculator, 8...Conductor temperature estimation unit, 9...Breakdown determination unit, 10...Environmental temperature estimation unit, 11...Inside air temperature sensor, 12...Outside air temperature sensor, 13...Solar radiation sensor, 14...Power distribution unit, 16...GPS device, 17...Clock, 18...Wireless communication device, 20...Vehicle, 23...Shielded space, 31...First term calculation unit, 32...Second term calculation unit, 33...Outside air temperature calculation unit, 34...Solar radiation calculation unit

Claims

1. a current detection unit that detects a current flowing through the conductor and outputs a current detection value; a current interruption unit that interrupts a current flowing through the conductor; a calculation unit that calculates a temperature rise value of the conductor due to Joule heat using the current detection value, estimates an environmental temperature of an environment that is a shielded space in which the conductor is wired, the environment being thermally shielded from the outside air environment and the inside air environment, based on the temperature rise value, outside air temperature information that is temperature information of the outside air environment of the vehicle, inside air temperature information that is temperature information of the inside air environment inside the vehicle cabin, and solar radiation information, by adding a temperature rise value based on the solar radiation information to a weighted average of the inside air temperature information and the outside air temperature information, estimates a temperature of the conductor by adding the environmental temperature in the shielded space to the temperature rise value, and determines whether or not to output a current cut-off instruction to the current cut-off unit based on the estimated temperature of the conductor. Vehicle control device.

2. The calculation unit sets the weighted average value according to a material of a body material of the vehicle that shields the outside air environment from the shielded space and a material of an interior lining that shields the inside air environment from the shielded space. The vehicle control device according to claim 1 .

3. The calculation unit sets a coefficient of the solar radiation information according to the outside air environment and the emissivity of a body material of the vehicle that shields the shielded space. The vehicle control device according to claim 1 .

4. The calculation unit acquires the outside air temperature information from an outside air temperature detection unit installed in the vehicle, acquires the inside air temperature information from an inside air temperature detection unit installed in the vehicle, and acquires the solar radiation information from a solar radiation detection unit installed in the vehicle. The vehicle control device according to claim 1 .

5. The calculation unit determines the current position of the vehicle based on GPS information received from a GPS information receiving unit, acquires weather information for the current position from a wireless communication unit using date and time information, and calculates the outside air temperature information and the solar radiation information based on the weather information. The vehicle control device according to claim 3.

6. a temperature rise value of the conductor due to Joule heat is calculated using a current detection value output from a current detection unit that detects a current flowing in the conductor; an environmental temperature of an environment that is a shielded space in which the conductor is wired, the environment being thermally shielded from the outside air environment and the inside air environment, between the outside air environment and the inside air environment of the vehicle, is estimated based on the temperature rise value, outside air temperature information that is temperature information of the outside air environment of the vehicle, inside air temperature information that is temperature information of the inside air environment of the vehicle cabin, and solar radiation information, by adding a temperature rise value based on the solar radiation information to a weighted average of the inside air temperature information and the outside air temperature information; an environmental temperature in the shielded space is added to the temperature rise value to estimate the temperature of the conductor; and a determination is made based on the estimated temperature of the conductor whether or not to output a current cut-off instruction to a current cut-off unit that cuts off the current flowing in the conductor. Overheat protection device.

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