Vehicle control device

Abstract

To provide a vehicle control device which can acquire a reference temperature fit to a variety of vehicles with a simple configuration and without a dedicated temperature sensor.SOLUTION: A vehicle control device includes: a current detection element 2 which detects a current flowing through a wiring harness which supplies power to an on-vehicle apparatus loaded on a vehicle; a reference temperature generation unit 5 which obtains a reference temperature according to the running state or the environment of the vehicle, using the detection value of a predetermined temperature sensor among a plurality of temperature sensors loaded on the vehicle, or a predetermined value; a temperature estimation unit 6 which calculates the estimated temperature of the wiring harness, using the current detection value from the current detection element and the reference temperature value obtained by the reference temperature generation unit 5; a cut-off determination unit 7 which determines cut-off based on the estimated temperature estimated by the temperature estimation unit 6; and a cut-off element 8 which cuts off the current which flows through the wiring harness, based on the determination by the cut-off determination unit 7.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Electrical and electronic devices use fuses that melt when an overcurrent blows to prevent overheating and smoke due to overcurrent. However, these fuses must be replaced after blowing, and due to variations in fusing characteristics, they are typically connected using thicker wire harnesses, which increases costs due to the labor required for replacement and the weight of the wire harness. Therefore, in recent years, a new method has been adopted that uses semiconductor switches using power semiconductors and temperature estimation technology to achieve the functionality of conventional fuses.

[0003] This temperature estimation technology detects the current flowing through the wire harness and uses this current value to calculate and estimate the heating temperature of the wire harness, protecting it by shutting off the semiconductor switch before it emits smoke or catches fire. If the overcurrent is eliminated by using this type of semiconductor switch for overheat protection, the semiconductor switch can be turned back on to restore power supply, eliminating the need for component replacement, which would be necessary if fuses were used. Furthermore, because there is no need to consider the fusing variations inherent in conventional fuses, thinner wire harnesses can be used, reducing weight and costs.

[0004] Patent Document 1 describes an overheat protection technology that uses temperature estimation of such a semiconductor switch and a wire harness. In the technology described in Patent Document 1, in order to protect an electric wire used to supply power from a power source to a load, the current flowing through the load is detected at predetermined time intervals. Then, the temperature rise of the electric wire is calculated using a relational expression relating the detected current flow and the heat dissipation and heat generation of the electric wire, and the calculated temperature rise is added to a reference temperature to estimate the temperature of the electric wire. If the estimated temperature of the electric wire exceeds a predetermined upper limit temperature, the supply of power from the power source to the load is stopped, thereby protecting the electric wire. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-130944 Summary of the Invention [Problem to be solved by the invention]

[0006] The front area of ​​a vehicle is equipped with not only electrical and electronic devices but also high-temperature, large-capacity heat sources such as an engine and a motor for driving the vehicle. In such an area, the air circulation state changes depending on the speed difference between when the vehicle is moving and when it is stopped. Furthermore, the temperature distribution in the front area changes in a complex manner depending on the load state of the engine and the motor. Therefore, the environmental temperature of the wire harness installed in the front area changes depending on the driving state and the influence of the heat sources such as the engine and the motor.

[0007] When estimating the temperature of a wire harness, the amount of temperature rise caused by the wire harness's self-heating due to current is calculated, and this temperature rise is added to the reference temperature, which is the environmental temperature where the wire harness is installed. If an error occurs in the acquired reference temperature, the estimated temperature will be incorrect, and the semiconductor switch may not trip at the appropriate temperature. For example, if the estimated temperature is higher than the actual temperature, the amount of current that can be supplied will decrease, which may cause the semiconductor switch to trip suddenly, reducing the amount of available current. Conversely, if the estimated temperature is lower than the actual temperature, the semiconductor switch may not trip at the appropriate trip threshold, which could cause the wire harness to smoke or catch fire.

[0008] One possible method for obtaining the reference temperature is to install a temperature sensor near the wire harness to be estimated. However, installing a temperature sensor requires installing temperature sensors in many wire harnesses inside the vehicle, which increases the cost of parts and the number of steps required for installation.

[0009] Another possible method for obtaining a reference temperature without installing a temperature sensor near the wire harness is to measure or simulate the temperature distribution in the engine compartment in advance based on the vehicle's operating conditions, such as speed and engine load. However, this method poses the problem of requiring a huge amount of work to adapt it to each vehicle, because the temperature distribution in the engine compartment varies depending on the vehicle model, engine size, and component layout.

[0010] The present invention aims to provide a vehicle control device that has a simple configuration that does not require a dedicated temperature sensor for acquiring the temperature of a wire harness and that is capable of acquiring a reference temperature that is compatible with various vehicles. [Means for solving the problem]

[0011] In order to solve the above problems, for example, the configurations described in the claims are adopted. The present application includes a plurality of means for solving the above-mentioned problems. One example of such a vehicle control device is a vehicle control device including a current detection element that detects a current flowing through a wire harness that supplies power to an on-board device mounted on a vehicle, and a temperature sensor that detects a detected value or a temperature value of a predetermined temperature sensor among a plurality of temperature sensors mounted on the vehicle depending on the running state or environment of the vehicle. a predetermined fixed value a temperature estimation unit that calculates an estimated temperature of the wire harness using a current detection value from the current detection element and the reference temperature value obtained by the reference temperature generation unit; a cutoff determination unit that determines whether to cut off the current based on the estimated temperature estimated by the temperature estimation unit; and a cutoff element that cuts off the current flowing through the wire harness based on the determination by the cutoff determination unit. When the detected value obtained from a predetermined temperature sensor is equal to or less than a certain temperature value that is lower than a predetermined fixed value, the detected value obtained from the temperature sensor is used as the reference temperature; when the detected value obtained from the predetermined temperature sensor is greater than the certain temperature value but less than the predetermined fixed value, the weighted average of the detected value obtained from the temperature sensor and the predetermined fixed value is used as the reference temperature; when the detected value obtained from the predetermined temperature sensor is greater than the predetermined fixed value, the predetermined fixed value is used as the reference temperature. [Effects of the Invention]

[0012] According to the present invention, the reference temperature used to estimate the temperature of the wire harness can be set to an optimum temperature depending on the driving state and driving environment, and excessive temperature of the wire harness can be reliably detected and cut off without excessively restricting the amount of current that can be supplied. Furthermore, since it is possible to obtain a more accurate environmental temperature than when using only a temperature sensor that detects the temperature in the area where the wire harness is installed, it is possible to relax the design margin and design a thinner wire harness. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a configuration diagram of a vehicle control device according to a first embodiment of the present invention. [Figure 2] 3 is a cross-sectional view showing a heat dissipation path of a wire harness, illustrating a temperature estimation process in the first embodiment of the present invention. FIG. [Figure 3] 3 is a circuit diagram illustrating a heat dissipation model expressed as an equivalent thermal circuit network, for explaining a temperature estimation process in the first embodiment of the present invention. FIG. [Figure 4] FIG. 4 is a block diagram showing the circuit of FIG. 3 converted into a transfer function with input heat generation amount Pw and output conductor temperature Tc. [Figure 5] 1 is a configuration diagram showing a specific configuration example (example 1) of a reference temperature generating unit of a vehicle control device in a first embodiment of the present invention. [Figure 6] 4 is a configuration diagram showing a specific configuration example (example 2) of the reference temperature generating unit of the vehicle control device in the first embodiment of the present invention. FIG. [Figure 7] 1 is a configuration diagram in which a vehicle control device according to a first embodiment of the present invention is adapted to a vehicle with an engine. [Figure 8] 1 is a diagram showing a configuration in which a first embodiment of the present invention is applied to a motorized vehicle. [Figure 9] FIG. 4 is a configuration diagram of a vehicle control device according to a second embodiment of the present invention. [Figure 10] FIG. 10 is a characteristic diagram showing an operation example (example 1) of the vehicle control device in the second embodiment of the present invention. [Figure 11] FIG. 10 is a characteristic diagram showing an operation example (example 2) of the vehicle control device in the second embodiment of the present invention. [Figure 12] FIG. 10 is a configuration diagram of a vehicle control device according to a third embodiment of the present invention. [Figure 13] FIG. 10 is a configuration diagram of a vehicle control device according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] <First embodiment> A vehicle control device according to a first embodiment of the present invention will be described below with reference to Figs. 1 to 8. The vehicle control device according to this embodiment is a control device for a device (on-board device) that is installed in a vehicle, which is a moving body such as an automobile. The vehicle control device functions as a heat protection system for a wire harness, which is a cable connected to the on-board device.

[0015] [Basic configuration of the heating protection system] FIG. 1 is a diagram showing a basic configuration of a heating protection system 1 for a wire harness in a vehicle control device to which the first embodiment is applied. In the heating protection system 1, the current flowing through the wire harness (not shown) is detected as a current value Iw by the current detection element 2. The first temperature sensor 3a and the second temperature sensor 3b are temperature sensors mounted on the vehicle, and are temperature sensors for devices mounted near the area where the wire harness is installed. In other words, these first temperature sensor 3a and second temperature sensor 3b are not installed to detect the temperature of the wire harness, but are installed to monitor the status of the in-vehicle devices, the status of the air conditioning equipment, etc. Specific examples of the first temperature sensor 3a and the second temperature sensor 3b will be described later.

[0016] The fixed value 4 is a temperature setting value that is a predetermined temperature used when the first temperature sensor 3a and the second temperature sensor 3b are not in use. For example, the fixed value 4 is the maximum design value of the environmental temperature in the area where the wire harness is installed. Note that the fixed value 4 is not fixed to a single value, but is a design parameter that is set to an arbitrary value for each area where the wire harness is installed.

[0017] The reference temperature generating unit 5 generates a reference temperature Ta, which is the ambient temperature of the wire harness, using the first temperature sensor 3a, the second temperature sensor 3b, and a fixed value. The reference temperature generating unit 5 acquires, from another control device, information on the vehicle operating state, such as whether the vehicle is running or stopped, and environmental information, such as the temperature around the vehicle, as vehicle operating state information 9, and generates the reference temperature Ta based on the acquired vehicle operating state information 9.

[0018] The temperature estimation unit 6 estimates and calculates the heating temperature of the wire harness using the current value from the current detection element 2 and the reference temperature Ta from the reference temperature generation unit 5. This estimation is performed using a model based on the heat generation amount and heat dissipation characteristics of the wire harness to be estimated. An example of a specific estimation method will be described later.

[0019] The interruption determination unit 7 outputs an interruption instruction when the temperature of the wire harness estimated by the temperature estimation unit 6 exceeds a predetermined threshold. The interruption element 8 interrupts the current flowing through the wire harness based on the interruption instruction from the interruption determination unit 7. A semiconductor switch made of a power semiconductor is used as the interruption element 8.

[0020] [Wire harness temperature estimation method] Next, an example of a method for estimating the temperature of the wire harness in the temperature estimating unit 6 will be described. FIG. 2 is a cross-sectional view showing a heat dissipation path of the wire harness in the temperature estimation unit 6. As shown in FIG. A wire harness consists of a conductor Wa through which current flows and an insulator Wb that covers it. When current flows through the conductor Wa, Joule heat is generated due to the resistance of the conductor Wa, generating heat Pw. The heat Pw is accumulated in the heat capacity C1 of the conductor Wa and is simultaneously conducted to the insulator Wb. In the insulator Wb, heat is accumulated in the heat capacity C2 of the insulator Wb and is thermally conducted to the surface of the insulator Wb via the thermal resistance R2 of the insulator Wb. The heat is then radiated to the surrounding air from the surface of the insulator Wb. The heat dissipation to the surrounding air is determined by the thermal resistance R3, which is determined by the heat transfer coefficient and radiant heat.

[0021] Figure 3 is a circuit diagram that shows this heat dissipation model in the form of an equivalent thermal circuit network. As shown in Figure 3, heat P, which corresponds to the heat generation Pw shown in Figure 2, is transmitted through the wire harness Twire. In the equivalent circuit of Figure 3, the thermal resistance R2 of the insulator Wb and the thermal resistance R3 during heat dissipation to the surrounding air are connected in series to the heat P. In addition, the wire harness Twire is connected to the heat capacity C1 of the conductor Wa and the heat capacity C2 of the insulator Wb. In Figure 3, Ta is the reference temperature.

[0022] FIG. 4 is a block diagram in which the equivalent circuit of FIG. 3 is converted into a transfer function in which the input is the heat generation amount Pw and the output is the conductor temperature Tc. As shown in Figure 4, the heat generation Pw is input, and a calculation is performed in which the reference temperature Ta is added to the value obtained by an arithmetic formula using a transfer function that uses the heat capacity C1, heat capacity C2, and thermal resistances R2 and R3, to obtain the conductor temperature Tc. The temperature of the wire harness is estimated based on the transfer function shown in FIG.

[0023] [Configuration of the reference temperature generation unit] Fig. 5 shows a configuration using a reference temperature generating unit 5a, which is a specific example (example 1) of the reference temperature generating unit 5. In Fig. 5, the configuration other than the reference temperature generating unit 5a is the same as the configuration already explained in Fig. 1. The reference temperature generating unit 5a receives the temperatures T1 and T2 from the first temperature sensor 3a and the second temperature sensor 3b, respectively, and also receives information 9a relating to the vehicle speed v.

[0024] When the vehicle is traveling (v>0 m / s), the reference temperature generating unit 5a outputs the value of the first temperature sensor 3a as the reference temperature value Ta. On the other hand, when the vehicle is stopped (v=0 m / s), the reference temperature generating unit 5a outputs the value of the second temperature sensor 3b as the reference temperature Ta. In this way, the reference temperature generating unit 5a acquires the reference temperature Ta by switching between the temperature T1 and the temperature T2 depending on the vehicle speed v, which is the traveling state of the vehicle.

[0025] Although the configuration shown here is one in which the reference temperature is switched when the vehicle speed becomes 0 m / s, the reference temperature generation process is not limited to this, and for example, the reference temperature may be switched when the vehicle speed becomes low even while the vehicle is running. The reference temperature may also be switched after a certain time has elapsed after the vehicle has stopped, and the switching conditions can be set arbitrarily. Furthermore, while the example shown in FIG. 5 shows an example in which two temperature sensors are used, the present invention is not limited to this, and the reference temperature generation unit 5a may be configured to use two or more temperature sensors and switch temperatures from two or more temperature sensors.

[0026] Fig. 6 shows a configuration using a reference temperature generating unit 5b, which is another specific example (example 2) of the reference temperature generating unit 5. In Fig. 6, the configuration other than the reference temperature generating unit 5b is the same as the configuration already described in Fig. 1. The reference temperature generating unit 5b receives the temperatures T1 and T2 from the first temperature sensor 3a and the second temperature sensor 3b, respectively, and also receives information 9a relating to the vehicle speed v.

[0027] The reference temperature generation unit 5b outputs the weighted average of temperatures T1 and T2 weighted by parameter a according to the vehicle speed v as the reference temperature Ta. The weighting parameter a is set appropriately according to the vehicle speed v. For example, when the vehicle is traveling at high speed (v≫0 m / s), a is set to 1 and the temperature T1 of the temperature sensor 3a is output as the reference temperature value Ta. When the vehicle speed becomes low (v>0 m / s), a is set to 0.5 and the intermediate value between temperatures T1 and T2 is output as the reference temperature Ta. When the vehicle is stopped (v=0 m / s), a is set to 0 and the value T2 of the temperature sensor 3b is output as the reference temperature Ta. In this way, the reference temperature Ta is set according to the vehicle speed, which is the traveling state of the vehicle. This allows the reference temperature to smoothly change from the sensor-detected temperature to a fixed value, enabling better temperature estimation.

[0028] In the example shown in Fig. 6, the relationship between the weighting parameter a and the velocity v is not limited to the above-mentioned conditions, but is a parameter that can be designed arbitrarily. Also, in the example shown in Fig. 6, an example using two temperature sensors is shown, but this is not limiting, and the reference temperature generating unit 5b may be configured to use two or more temperature sensors.

[0029] [Specific configuration example when applied to a vehicle] FIG. 7 shows a specific example in which the vehicle control device of this embodiment is applied to a vehicle. In the example shown in Figure 7, an engine intake air temperature sensor, which is an outside air temperature sensor that detects the outside air temperature of the vehicle, or an outside air temperature sensor of an air conditioner, is used as the first temperature sensor 3a, and an engine coolant temperature sensor that detects the temperature of the engine 20, which is an equipment installed in the vehicle, is used as the second temperature sensor 3b.

[0030] Inside the vehicle, power is supplied to a load device through a wire harness 10, the temperature of which is to be estimated. The wire harness 10 is connected to a current sense MOS-FET 8a, which serves as a cutoff element 8, and the current sense MOS-FET 8a is connected to a battery 11. The current sense MOS-FET 8a has an input terminal for a cutoff signal that cuts off the current flowing through the wire harness 10, and a current detection element that outputs a minute current proportional to the current flowing through the wire harness 10. The output current from the current detection element flows through a resistor 12 and is converted into a voltage value. This voltage value is equivalent to a signal that indicates the current flowing through the wire harness 10.

[0031] The engine 20 shown in FIG. 7, the first temperature sensor 3a that detects the intake air temperature and the outside air temperature, the second temperature sensor 3b that is an engine coolant temperature sensor, and the wire harness 10 are arranged in the front area of ​​the vehicle.

[0032] The computing unit 13 includes a reference temperature generating unit 5, a temperature estimating unit 6, a shutoff determining unit 7, and a drive managing unit 14. The computing unit 13 may be a microcomputer or the like. Temperature information from the first temperature sensor 3a and the second temperature sensor 3b and vehicle speed information 9a are input to the reference temperature generation unit 5. The reference temperature Ta output by the reference temperature generation unit 5 is input to the temperature estimation unit 6. The temperature estimation unit 6 also receives a voltage value V(Iw) of the resistor 12, which indicates the current flowing through the wire harness 10. The temperature estimation unit 6 estimates the temperature of the wire harness 10 by the above-described method using the reference temperature Ta and the voltage value V(Iw).

[0033] The shutdown determination unit 7 determines whether to shut down the load device based on the result of estimation by the temperature estimation unit 6. If the estimated temperature value is higher than a predetermined threshold, the shutdown determination unit 7 outputs a shutdown command to the drive management unit 14. The drive management unit 14 receives a drive command for the load device from the outside. 15Upon receiving the interruption command from the interruption determination unit 7, the drive management unit 14 outputs a drive signal to the current sense MOS-FET 8a. The current sense MOS-FET 8a is turned on by the drive signal and supplies power to the load device. When the drive management unit 14 receives an interruption command from the interruption determination unit 7, it forcibly sends an interruption signal to the current sense MOS-FET 8a, thereby interrupting the current flowing through the wire harness 10.

[0034] 5, the reference temperature generating unit 5 outputs the value of the first temperature sensor 3a that detects the intake air temperature and the outside air temperature as the reference temperature value Ta when the vehicle is traveling (v>0 m / s). Furthermore, when the vehicle is stopped (v=0 m / s), the reference temperature generating unit 5 outputs the value of the second temperature sensor 3b that detects the engine temperature as the reference temperature Ta. In this way, the reference temperature generating unit 5 switches the reference temperature Ta from the outside air temperature to the temperature of the on-board equipment according to the vehicle speed v that indicates the traveling state of the vehicle, and supplies the reference temperature Ta to the temperature estimating unit 6.

[0035] When the vehicle is running, outside air is taken in and circulated in the front area where the wire harness 10 is installed. Therefore, when the vehicle is running, the engine intake air temperature sensor value and the outside air temperature sensor value, which are close to the outside air temperature, are set to the reference temperature. On the other hand, when the vehicle is stopped, the air circulation in the front area becomes poor and the influence of heat radiation from the engine becomes large. Therefore, when the vehicle is stopped, the temperature values ​​of the coolant temperature sensor and oil temperature sensor, which are close to the engine temperature, are set to the reference temperature. In this way, by the reference temperature generation unit 5 setting the reference temperature, the reference temperature can be obtained at a temperature close to the actual ambient temperature of the wire harness when estimating the temperature of the wire harness 10, and therefore the temperature estimation unit 6 can improve the accuracy of temperature estimation.

[0036] The front area of ​​a vehicle is equipped with high-temperature, large-heat-capacity equipment such as an engine. In estimating the temperature of a wire harness, if the reference temperature Ta is always set based on the highest temperature in the area where the wire harness is installed, the estimated temperature of the wire harness will be too high, resulting in excessive restriction of the amount of current supplied. According to this embodiment, the temperature sensor that serves as the basis for the reference temperature Ta is switched depending on the driving state, so that the estimated temperature uses a reference temperature that is more suited to the actual situation, and excessive current restriction can be avoided.

[0037] 7, an engine intake air temperature sensor and an air conditioner outside air temperature sensor are used as the first temperature sensor 3a, but the temperature sensors are not limited to these and other temperature sensors may be used as long as they are configured to acquire similar temperatures. Also, a coolant temperature sensor is used to acquire the engine temperature, but the engine temperature is not limited to these and other similar temperatures such as engine oil temperature may be acquired as long as they are configured to acquire similar temperatures.

[0038] In addition, in the example of Figure 7, a configuration was described in which the first temperature sensor 3a and the second temperature sensor 3b are switched depending on the vehicle speed v, but the reference temperature generation unit 5 may also be configured to output a weighted average value based on the weighting parameter a shown in Figure 6 as the reference temperature Ta.

[0039] [Example for electric vehicles] FIG. 8 shows an example of the configuration of the front area of ​​an electric vehicle in which the driving device of the vehicle is a motor. In the case of an electric vehicle, the heat source mounted in the front area is the drive motor. Therefore, a motor coolant temperature sensor indicating the temperature of the motor can be used as the second temperature sensor 3b. In this case, the reference temperature generating unit 5 receives the temperature from the first temperature sensor 3a, which detects the outside air temperature obtained from an air conditioner or the like, and the temperature from the motor coolant temperature sensor 3b, which detects the temperature of the motor. When the vehicle is traveling (v>0 m / s), the reference temperature generating unit 5 outputs the value of the first temperature sensor 3a, which detects the outside air temperature, as the reference temperature value Ta. When the vehicle speed is stopped (v=0 m / s), the reference temperature generating unit 5 outputs the value of the second temperature sensor 3b, which indicates the motor coolant temperature, as the reference temperature Ta. In this way, even in an electric vehicle, the temperature of the on-board equipment is acquired by switching from the outside air temperature to the temperature of the on-board equipment depending on the vehicle speed, which is the traveling state of the vehicle.

[0040] <Second embodiment> Next, a vehicle control device according to a second embodiment of the present invention will be described with reference to Figures 9 to 11. In Figures 9 to 11, parts corresponding to those in Figures 1 to 8 described in the first embodiment are given the same reference numerals. The vehicle control device of this embodiment is also a control device for an on-board device that is installed in a vehicle, which is a moving body such as an automobile, as in the first embodiment. The vehicle control device of the second embodiment also has a function as a heat protection system for a wire harness, which is a cable connected to an on-board device.

[0041] [Configuration of the Heat Protection System] FIG. 9 shows the configuration of a heating protection system for a wire harness in a vehicle control device to which this embodiment is applied. In the overheat protection system of this embodiment, the current flowing through the wire harness is detected by the current detection element 2. The temperature sensor 3a is a temperature sensor mounted on the vehicle and is installed in equipment mounted near the area where the wire harness is installed. The fixed value 4 is a temperature setting value used when the temperature sensor 3a is not used.

[0042] For example, fixed value 4 is the maximum design value of the environmental temperature in the area where the wire harness is installed. Fixed value 4 is a design parameter that is not fixed to a single value but is set to an arbitrary value (predetermined value).

[0043] The reference temperature generating unit 5c generates the ambient temperature of the wire harness (reference temperature Ta in temperature estimation) using the temperature sensor 3a, the fixed value 4, and the ambient temperature of the vehicle. The reference temperature generating unit 5c generates the reference temperature Ta based on the information 9b of the ambient temperature of the vehicle.

[0044] The temperature estimation unit 6 estimates and calculates the heating temperature of the wire harness using the current value from the current detection element 2 and the reference temperature from the reference temperature generation unit 5c. This estimation is performed using a model based on the heat generation amount and heat dissipation characteristics of the wire harness to be estimated. The model based on the heat generation amount and heat dissipation characteristics of the wire harness is as described in the first embodiment.

[0045] The interruption determination unit 7 outputs an interruption instruction to the interrupting element 8 when the estimated temperature of the wire harness estimated by the temperature estimation unit 6 exceeds a predetermined threshold value. The interrupting element 8 interrupts the current flowing through the wire harness based on an interruption instruction from the interruption determining unit 7. As the interrupting element 8, a semiconductor switch made of a power semiconductor is used.

[0046] [Reference temperature generation process] Fig. 10 shows an example (example 1) of the operation of reference temperature generating unit 5c in this embodiment. The vertical axis of Fig. 10 represents the temperature detected by temperature sensor 3a, and the horizontal axis represents the ambient temperature. In Fig. 10, the solid line characteristic Ta represents the reference temperature characteristic, and the dashed line characteristic Ts represents the value from temperature sensor 3a.

[0047] The reference temperature generation unit 5c switches between the temperature value of the temperature sensor 3a and a fixed value 4 depending on the ambient temperature of the vehicle. When the ambient temperature is low, the value of the temperature sensor 3a is output as the reference temperature Ta. As shown in FIG. 10, when the ambient temperature rises and the temperature detected by the temperature sensor 3a becomes higher than the constant temperature Tth, the measurement error of the temperature sensor 3a increases. The constant temperature Tth is, for example, 80°C. When the temperature detected by the temperature sensor 3a is equal to or lower than the constant temperature Tth, the difference between the detected value Ts of the temperature sensor 3a and the reference temperature Ta is guaranteed to be within a certain error range. This range is the temperature sensor compensation range tx. In the sensor compensation range tx (range of ambient temperature α) where the temperature detected by the temperature sensor 3a is equal to or lower than the constant temperature Tth, the reference temperature generation unit 5c uses the detected temperature Ts of the temperature sensor 3a as the reference temperature.

[0048] On the other hand, when the temperature Ts detected by the temperature sensor 3a becomes higher than the constant temperature Tth, the measurement error will be higher or lower than the actual temperature. In other words, there is a tendency for variation ty to occur due to individual differences in the temperature sensor 3a. In such a case, if the temperature value of the temperature sensor 3a is used as the reference temperature, an error will occur in the estimated temperature of the wire harness. If the estimated temperature becomes lower than the actual temperature, the current flowing through the wire harness may not be properly interrupted, which could result in smoke or fire.

[0049] As described above, in this embodiment, in the range β where the error in the detected value of the temperature sensor 3a becomes large and the temperature value becomes unreliable, the reference temperature is switched to the fixed value 4. The fixed value 4 here is set to a value that is the maximum temperature designed for the location where the wire harness is installed. As a result, the estimated temperature of the wire harness is estimated to be higher than the actual temperature, so that it can be reliably shut off before smoke or fire occurs. In other words, according to this embodiment, it is possible to configure the temperature to be on the safe side when the temperature sensor 3a is unreliable.

[0050] Although the value of the temperature sensor 3a can be used for the environmental temperature on the horizontal axis of FIG. 10, other temperature sensors may also be used as long as it is possible to detect conditions in which the value of the temperature sensor 3a is unreliable.

[0051] Fig. 11 shows another example (example 2) of the operation of reference temperature generating unit 5c in this embodiment. In the example of Fig. 10, when the temperature value of temperature sensor 3a falls within the range β of unreliable conditions, the temperature value is switched to a fixed value 4. 11, on the other hand, the temperature is gradually changed to a fixed value rather than being changed to a fixed value at a certain value. For example, after the temperature detected by the temperature sensor 3a exceeds a certain temperature Tth, within a certain temperature range γ, the weighted average of the value of the temperature sensor 3a and the value of the fixed value 4 is set as the reference temperature. Then, in a range β where the environmental temperature is even higher, a fixed value is set as the reference temperature.

[0052] In this embodiment, the temperature detected by the temperature sensor 3a, which is proportional to the ambient temperature, is switched to a fixed value when it exceeds a predetermined threshold value Tth, but this threshold value Tth is set appropriately depending on the performance of the temperature sensor 3a and is not determined to a single value. Also, although the temperature sensor 3a is used in this embodiment, a configuration in which multiple temperature sensors are connected may be used.

[0053] <Third embodiment> Next, a vehicle control device according to a third embodiment of the present invention will be described with reference to Fig. 12. In Fig. 12, parts corresponding to Figs. 1 to 11 described in the first and second embodiments are given the same reference numerals. Like the first and second embodiments, the vehicle control device of this embodiment is a control device for an on-board device that is installed in a vehicle, which is a moving body such as an automobile, and is mounted on the vehicle. This vehicle control device also functions as a heat protection system for a wire harness, which is a cable connected to the on-board device.

[0054] [Configuration of the Heat Protection System] FIG. 12 shows the configuration of a heating protection system for a wire harness in a vehicle control device to which this embodiment is applied. 12, multiple temperature values ​​are input to the reference temperature generating unit 5d from the first temperature sensor 3a and the second temperature sensor 3b. For example, the first temperature sensor 3a detects the temperature of the intake air of the engine, and the second temperature sensor 3b detects the outside air temperature installed in an air conditioner. In this case, both temperature sensors detect temperature values ​​based on the outside air temperature, and it is preferable that the first temperature sensor 3a and the second temperature sensor 3b detect the temperature of the same part or location.

[0055] The reference temperature generating unit 5d compares these temperature values, and when the difference between these temperature values ​​is smaller than a predetermined value, outputs the temperature value based on the first temperature sensor 3a and the second temperature sensor 3b as the reference temperature Ta. When the difference between the temperature values ​​of the first temperature sensor 3a and the second temperature sensor 3b is larger than the predetermined value, the reference temperature generating unit 5d outputs a fixed value 4 as the reference temperature Ta.

[0056] 12, if a failure occurs in either the first temperature sensor 3a or the second temperature sensor 3b, the difference between these temperature values ​​becomes significantly large, making it possible to detect the failure. In other words, when it is detected that the temperature values ​​of the first temperature sensor 3a and the second temperature sensor 3b have become unreliable, the reference temperature generating unit 5d outputs a fixed value 4 as the reference temperature Ta. The value of the fixed value 4 is set to the maximum design temperature of the location where the wire harness whose temperature is to be estimated is installed. This makes it possible to prevent the temperature estimated by the temperature estimating unit 6 from becoming lower than the actual temperature of the wire harness, thereby reliably preventing the wire harness from emitting smoke or catching fire.

[0057] 12, the first temperature sensor 3a and the temperature sensor 3b may be other than the sensor for detecting the temperature of intake air of the engine or the temperature sensor for detecting the outside air temperature of the air conditioner, as long as they can detect a failure of the first temperature sensor 3a and the second temperature sensor 3b. The first temperature sensor 3a and the second temperature sensor 3b are selected appropriately depending on the location of the wire harness whose temperature is to be estimated.

[0058] <Fourth embodiment> Next, a vehicle control device according to a fourth embodiment of the present invention will be described with reference to Fig. 13. In Fig. 13, parts corresponding to Figs. 1 to 12 described in the first to third embodiments are given the same reference numerals. As with the first to third embodiments, the vehicle control device of this embodiment is a control device for an on-board device that is installed in a vehicle, which is a moving body such as an automobile, and is mounted on the vehicle, and the vehicle control device has the function of a heat protection system for a wire harness, which is a cable connected to the on-board device.

[0059] The vehicle in which the vehicle control device of this embodiment is installed is a so-called hybrid vehicle equipped with both an engine and a motor. There are various types of hybrid vehicles equipped with both an engine and a motor, but in this embodiment, any hybrid type may be used.

[0060] [Configuration of the Heat Protection System] FIG. 13 shows the configuration of a heating protection system for a wire harness in a vehicle control device to which this embodiment is applied. In the configuration shown in FIG. 13, the reference temperature generating unit 5e receives the temperature value from the first temperature sensor 3a, multiple temperature values ​​from the two second temperature sensors 3b-1 and 3b-2, and the temperature value from the second temperature sensor 3b. As the first temperature sensor 3a, a sensor that is mounted on an air conditioner and detects the outside air temperature is used. One of the two second temperature sensors, second temperature sensor 3b-1, is an engine temperature sensor that detects the temperature of engine coolant. An engine oil temperature sensor may be used instead of the engine coolant temperature sensor. A motor coolant temperature sensor is used as the other second temperature sensor 3b-1.

[0061] The reference temperature generating unit 5e acquires information 9 on the vehicle operating state, and switches the temperature adopted as the reference temperature Ta between the first temperature sensor 3a and the second temperature sensor 3b-1 or 3b-2 depending on the vehicle speed, similar to the reference temperature generating unit 5a described in the first embodiment. The switching depending on the vehicle speed is performed, for example, depending on whether the vehicle is moving or stopped. However, in this embodiment, there are two second temperature sensors 3b-1, 3b-2, and the reference temperature generation unit 5e compares the temperatures detected by these two second temperature sensors 3b-1, 3b-2. When outputting the temperatures detected by the second temperature sensors as the reference temperature, the reference temperature generation unit 5e sets the higher detected temperature of the two second temperature sensors 3b-1, 3b-2 as the reference temperature.

[0062] This allows the reference temperature to be set according to the actual temperature in the front area, even in hybrid vehicles equipped with both an engine and a motor. For example, during a stop period after driving using mainly the motor with the engine stopped, the temperature of the motor coolant will be higher than the engine temperature. Therefore, by using the motor coolant temperature sensor 3b-1 as the second temperature sensor, an appropriate reference temperature can be set. On the other hand, during a stop period after driving using mainly the engine with little use of the motor, the engine temperature will be higher than the motor coolant temperature. Therefore, by using the engine temperature sensor 3b-2 as the second temperature sensor, an appropriate reference temperature can be set. Therefore, even in hybrid vehicles, an appropriate reference temperature can be set.

[0063] In this embodiment as well, when there is a significant difference between at least two of the temperature values ​​of the temperature sensors 3a, 3b-1, and 3b-2, the reference temperature is set to fixed value 4. Alternatively, as explained in the third embodiment, when the temperature is outside the temperature sensor guaranteed range, fixed value 4 may be set to the reference temperature.

[0064] [Variations] The embodiment examples described so far have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. For example, the specific examples of temperature sensors described in the above-mentioned embodiments, such as an engine temperature sensor, a motor coolant temperature sensor, and a sensor mounted on an air conditioner to detect outside air temperature, are each shown as suitable examples, and any other sensor installed in a vehicle that measures the temperature near the wire harness for which temperature estimation is desired may also be used. As an example, the engine temperature sensor may be a temperature sensor for engine coolant, an engine oil temperature sensor, or any of a variety of other temperature sensors installed on or near the engine.

[0065] In addition, in the configuration diagrams shown in Figure 1 and elsewhere, only the control lines and information lines considered necessary for explanation are shown, and not all control lines and information lines in the product are necessarily shown. In reality, it can be assumed that almost all components are interconnected. Furthermore, when the system of this example is configured using an information processing device such as a computer, the program that realizes the heating protection system of the vehicle control device may be stored in non-volatile storage or memory within the computer, or may be stored on a recording medium such as external memory, an IC card, an SD card, or an optical disk and transferred. [Explanation of symbols]

[0066] 1...heating protection system, 2...current detection element, 3a...first temperature sensor, 3b, 3b-1, 3b-1...second temperature sensor, 4...fixed value, 5, 5a, 5b, 5c, 5d, 5e...reference temperature generation unit, 6...temperature estimation unit, 7...shutdown determination unit, 8...shutdown element, 8a...current sense MOS-FET, 9...vehicle operating state information, 9, 9a, 9b...information (vehicle speed), 10...wire harness, 11...battery, 12...resistor, 13...calculator, 14...drive management unit, 15 …Drive command, 20…Engine

Claims

1. a current detection element that detects a current flowing through a wire harness that supplies power to an in-vehicle device mounted on a vehicle; a reference temperature generating unit that obtains a reference temperature using a detection value of a predetermined temperature sensor among a plurality of temperature sensors mounted on the vehicle or a predetermined fixed value according to a running state or environment of the vehicle; a temperature estimation unit that calculates an estimated temperature of the wire harness using a current detection value from the current detection element and a reference temperature value obtained by the reference temperature generation unit; a shutoff determination unit that determines whether to shut off the circuit based on the estimated temperature estimated by the temperature estimation unit; a breaking element that breaks the current flowing through the wire harness based on the determination by the break determination unit, When the detected value obtained from the predetermined temperature sensor is equal to or lower than a certain temperature value that is lower than the predetermined fixed value, the detected value obtained from the temperature sensor is set as the reference temperature; When the detected value obtained from the predetermined temperature sensor exceeds the constant temperature value and is equal to or less than the predetermined fixed value, a weighted average of the detected value obtained from the temperature sensor and the predetermined fixed value is set as the reference temperature; When the detected value obtained from the predetermined temperature sensor exceeds the predetermined fixed value, the predetermined fixed value is set as the reference temperature. Vehicle control device.

2. The predetermined temperature sensor acquires the temperature by switching to a specific temperature sensor among a plurality of temperature sensors mounted on the vehicle depending on the running state of the vehicle. The vehicle control device according to claim 1.

3. The detection value obtained from the predetermined temperature sensor is calculated based on a weighted average of multiple temperature sensor values ​​obtained from multiple temperature sensors mounted on the vehicle depending on the running state of the vehicle. The vehicle control device according to claim 1.

4. The predetermined temperature sensor is acquired by switching between a temperature sensor mounted on the vehicle that detects a temperature dependent on the outside air temperature and a temperature sensor that detects the temperature of an equipment mounted on the vehicle, depending on the running state of the vehicle. The vehicle control device according to claim 1.

5. the temperature sensor mounted on the vehicle for detecting the outside air temperature is a temperature sensor for detecting the intake air temperature of an engine, The temperature sensor for detecting the temperature of the device mounted on the vehicle is a temperature sensor for detecting the temperature of the engine. The vehicle control device according to claim 4.

6. the temperature sensor mounted on the vehicle for detecting the outside air temperature is a temperature sensor for detecting the outside air temperature, The temperature sensor for detecting the temperature of the device mounted on the vehicle is a temperature sensor for detecting the temperature of a motor that drives the vehicle. The vehicle control device according to claim 4.

7. the temperature sensor mounted on the vehicle for detecting the outside air temperature is a temperature sensor for detecting the outside air temperature, The temperature sensor for detecting the temperature of the equipment mounted on the vehicle is a temperature sensor that detects the temperature of the engine and a temperature sensor that detects the temperature of the motor that drives the vehicle, whichever is higher. The vehicle control device according to claim 4.

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