Control device for vehicle

Abstract

To provide a control device for a vehicle capable of suppressing fluctuation of electric power to be supplied to an electric load at restart of an engine.SOLUTION: A control device for a vehicle automatically stops an engine when a predetermined automatic stop condition is satisfied, and restarts the automatically stopped engine when a predetermined restart condition is satisfied. Electric power Pc obtained by subtracting electric power Pr required for restarting the engine from electric power Pd that can be discharged by a high voltage battery is set as electric power that can be consumed at restart of the engine by a voltage converter.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Conventionally, Patent Document 1 proposes a technology in which, when specific idling stop conditions are met, idling stop is performed when the vehicle is stopped and when the vehicle is traveling at a certain speed, and when the engine is restarted from idling stop performed when the vehicle is stopped, operation of the DC-DC converter is stopped and charging of the low-voltage storage device is halted, while when the engine is restarted from idling stop performed when the vehicle is traveling at a certain speed, operation of the DC-DC converter is continued. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-55577 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technology as described above, when the engine is restarted from an idling stop performed while the vehicle is stopped, operation of the DC-DC converter is stopped and charging of the low-voltage storage device is halted, which causes a problem that the power supplied to the electrical load connected to the output side of the DC-DC converter fluctuates when the engine is restarted.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a vehicle control device that can suppress fluctuations in power supplied to an electrical load when the engine is restarted. [Means for solving the problem]

[0006] The vehicle control device of the present invention is provided on a vehicle including a high-voltage battery, an engine starting device that starts an engine using power supplied from the high-voltage battery, a voltage converter that steps down and outputs the power supplied from the high-voltage battery, and an electrical load to which the output power of the voltage converter is supplied, and is a vehicle control device that automatically stops the engine when a predetermined automatic stop condition is met and restarts the automatically stopped engine when a predetermined restart condition is met, and is configured to include a control unit that executes output limitation by setting the power that can be consumed by the voltage converter when the engine is restarted to the power that can be discharged from the high-voltage battery minus the power required to restart the engine. Effect of the Invention

[0007] The present invention can provide a vehicle control device that can suppress fluctuations in power supplied to an electric load when the engine is restarted. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a vehicle equipped with a vehicle control device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a control circuit of a vehicle equipped with a vehicle control device according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a conceptual diagram for explaining the output limitation of the voltage converter executed by the vehicle control device according to one embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart showing a converter limiting operation of the vehicle control device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A vehicle control device according to one embodiment of the present invention is provided in a vehicle including a high-voltage battery, an engine starting device that starts an engine using power supplied from the high-voltage battery, a voltage converter that steps down and outputs the power supplied from the high-voltage battery, and an electrical load to which the output power of the voltage converter is supplied, and is configured to automatically stop the engine when a predetermined automatic stop condition is satisfied and to restart the automatically stopped engine when a predetermined restart condition is satisfied, and is characterized in that the vehicle control device includes a control unit that executes output limitation to set the power that is obtained by subtracting the power required for restarting the engine from the power that the high-voltage battery can discharge as the power that can be consumed by the voltage converter when the engine is restarted. As a result, the vehicle control device according to one embodiment of the present invention can suppress fluctuations in the power supplied to the electrical load when the engine is restarted. EXAMPLES

[0010] Hereinafter, a vehicle equipped with a vehicle control device according to an embodiment of the present invention will be described with reference to the drawings.

[0011] As shown in FIG. 1, a vehicle 1 includes an engine 2, a motor 3, a high-voltage battery 4, a voltage converter 5, a low-voltage battery 6, and an electric load .

[0012] The engine 2 is formed with a plurality of cylinders. In this embodiment, the engine 2 generates power by performing a series of four strokes, which are an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, for each cylinder. In this embodiment, the power generated by the engine 2 is transmitted to the drive wheels via a power transmission path (not shown).

[0013] The motor 3 is provided to be interlocked with the crankshaft of the engine 2. The motor 3 has a function as an engine starting device that starts the engine 2 by rotating when power is supplied from the high-voltage battery 4, and a function as a generator that converts the power generated by the engine 2 into electric power.

[0014] The high-voltage battery 4 is a rechargeable secondary battery, for example a lithium-ion battery. The high-voltage battery 4 accumulates the power generated by the motor 3 and supplies the power to the motor 3 and the voltage converter 5.

[0015] The voltage converter 5 converts the high-voltage power supplied from the high-voltage battery 4 into low-voltage power. The low-voltage power converted by the voltage converter 5 is supplied to the low-voltage battery 6 and the electrical load 7.

[0016] The low-voltage battery 6 is a rechargeable secondary battery, such as a lead battery or a lithium-ion battery. The low-voltage battery 6 stores the low-voltage power converted by the voltage converter 5 and supplies the power to the electric load 7.

[0017] The electric loads 7 are operated by the low-voltage power converted by the voltage converter 5 and the low-voltage power supplied from the low-voltage battery 6. The electric loads 7 are made up of vehicle electrical components including lights, an air conditioning fan, a navigation system, an audio system, and the like.

[0018] 2, the vehicle 1 is further configured to include an ECU (Electronic Control Unit) 8. The ECU 8 is configured by a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, etc., an input port, and an output port.

[0019] The ROM of this computer unit stores various constants, various maps, and the like, as well as a program for causing the computer unit to function as the ECU 8. That is, the CPU executes the program stored in the ROM using the RAM as a working area, whereby the computer unit functions as the ECU 8 in this embodiment.

[0020] Connected to the input port of the ECU 8 are various sensors including a water temperature sensor 11 which detects the temperature of the cooling water for the engine 2, an oil temperature sensor 12 which detects the temperature of the lubricating oil for the engine 2, a battery sensor 13 which detects the charge / discharge current of the high-voltage battery 4, a battery temperature sensor 14 which detects the temperature of the high-voltage battery 4, an accelerator opening sensor 16 which detects the amount of accelerator pedal operation (hereinafter simply referred to as "accelerator opening"), a brake stroke sensor 18 which detects the amount of brake pedal operation, a vehicle speed sensor 19 which detects the vehicle speed, and an engine speed sensor 20 which detects the engine speed of the engine 2 (hereinafter simply referred to as "engine speed").

[0021] An output port of the ECU 8 is connected to various control objects including the voltage converter 5, an inverter 21 for controlling the motor 3, an injector 22 for supplying fuel to the engine 2, and an ignition device 23 for igniting fuel in a combustion chamber of the engine 2. When the engine 2 is configured as an engine that does not require a spark plug, such as a diesel engine, the ignition device 23 is excluded from the configuration of the vehicle 1.

[0022] The ECU 8 controls various control targets connected to the output ports based on information obtained from various sensors connected to the input ports. The ECU 8 automatically stops the engine 2 when a predetermined automatic stop condition is met, and restarts the engine 2 when a predetermined restart condition is met.

[0023] In this embodiment, when the engine 2 is running, the accelerator opening detected by the accelerator opening sensor 16 is substantially zero, the brake stroke detected by the brake stroke sensor 18 is equal to or greater than a predetermined amount, and the vehicle speed detected by the vehicle speed sensor 19 is equal to or less than a predetermined value (e.g., 7 km / h), the ECU 8 determines that the automatic stop condition is met and automatically stops the engine 2 by stopping the supply of fuel by the injector 22 and the ignition by the ignition device 23.

[0024] Furthermore, when the brake stroke detected by the brake stroke sensor 18 becomes substantially zero while the engine 2 is automatically stopped, or when the accelerator opening detected by the accelerator opening sensor 16 becomes equal to or greater than a predetermined value, the ECU 8 determines that the restart conditions are met and controls the inverter 21 to cause the motor 3 to rotate the crankshaft of the engine 2, and then restarts the engine 2 by starting the supply of fuel by the injector 22 and ignition by the ignition device 23.

[0025] The ECU 8 has a function as a control unit 30 that executes output limitation by subtracting the power Pr required for restarting the engine 2 from the dischargeable power Pd of the high-voltage battery 4, and setting the result as the power Pc that can be consumed by the voltage converter 5 when restarting the engine 2. The ECU 8 executes the output limitation when the restart condition is satisfied, and releases the output limitation when the restart of the engine 2 is completed.

[0026] Hereinafter, the output limitation of the voltage converter 5 executed by the ECU 8 will be described with reference to FIG.

[0027] The ECU 8 estimates the dischargeable power Pd of the high-voltage battery 4 based on the SOC (State Of Charge) of the high-voltage battery 4, the temperature of the high-voltage battery 4 detected by the battery temperature sensor 14, and the SOH (State of Health) of the high-voltage battery 4.

[0028] In this embodiment, the ECU 8 calculates the SOC and SOH of the high-voltage battery 4 based on the charge / discharge current detected by the battery sensor 13. A discharge capability map is stored in the ROM of the ECU 8 in which the SOC, temperature, and SOH of the high-voltage battery 4 are associated with the dischargeable power Pd of the high-voltage battery 4. The ECU 8 estimates the dischargeable power Pd of the high-voltage battery 4 based on the discharge capability map.

[0029] In this embodiment, the ECU 8 estimates the electric power Pr required to restart the engine 2 based on the friction at the time of restarting the engine 2. The friction at the time of restarting the engine 2 is affected by the temperature of the coolant for the engine 2 and the temperature of the lubricating oil for the engine 2.

[0030] Therefore, the ECU 8 estimates the electric power Pr required to restart the engine 2 based on the temperature of the coolant detected by the water temperature sensor 11 and the temperature of the lubricating oil detected by the oil temperature sensor 12.

[0031] The ROM of the ECU 8 stores a dischargeable map in which the dischargeable electric power Pd of the high-voltage battery 4 is associated with the temperature of the coolant for the engine 2 and the temperature of the lubricating oil for the engine 2. The ECU 8 estimates the electric power Pr required to restart the engine 2 based on the dischargeable map.

[0032] The ECU 8 subtracts the power Pr required to restart the engine 2 from the dischargeable power Pd of the high-voltage battery 4 to calculate the power Pc that can be consumed by the voltage converter 5 to restart the engine 2. The ECU 8 executes the output limit of the voltage converter 5 by limiting the power consumed by the voltage converter 5 to restart the engine 2 to the power Pc.

[0033] The converter limiting operation by the ECU 8 configured as above will be described with reference to Fig. 4. The converter limiting operation described below is executed when the ECU 8 automatically stops the engine 2.

[0034] First, in S1, the ECU 8 determines whether or not a restart condition for the engine 2 is satisfied. If it is determined in S1 that the restart condition for the engine 2 is satisfied, the ECU 8 executes the process of S2.

[0035] When it is determined in S1 that the restart condition of the engine 2 is not satisfied, the ECU 8 executes the process of S1. That is, when it is determined in S1 that the restart condition of the engine 2 is not satisfied, the output limiting operation goes into a standby state to wait for the restart condition of the engine 2 to be satisfied.

[0036] In S2, if the ECU 8 is not limiting the output of the voltage converter 5, the ECU 8 limits the output of the voltage converter 5. After executing the process of S2, the ECU 8 executes the process of S3. In S3, the ECU 8 determines whether or not the complete combustion condition of the engine 2 is satisfied.

[0037] In S3, the ECU 8 determines that the complete combustion condition of the engine 2 is satisfied when the engine 2 is in a state where it can operate autonomously. For example, the ECU 8 determines whether the complete combustion condition of the engine 2 is satisfied based on the transition of the engine speed detected by the engine speed sensor 20.

[0038] If it is determined in S3 that the complete combustion condition of the engine 2 is satisfied, the ECU 8 executes the process of S4. If it is determined in S3 that the complete combustion condition of the engine 2 is not satisfied, the ECU 8 executes the process of S2.

[0039] That is, when it is determined in S3 that the complete combustion condition of the engine 2 is not satisfied, the ECU 8 continues to limit the output of the voltage converter 5. In S4, the ECU 8 releases the output limit of the voltage converter 5. After executing the process of S4, the ECU 8 ends the converter limiting operation.

[0040] As described above, the vehicle control device of this embodiment sets the power Pc obtained by subtracting the power Pr required to restart the engine 2 from the dischargeable power Pd of the high-voltage battery 4 as the power that can be consumed by the voltage converter 5 when the engine 2 is restarted, and therefore can suppress fluctuations in the power supplied to the electrical load 7 when the engine 2 is restarted while ensuring the restartability of the engine 2.

[0041] In addition, the vehicle control device of this embodiment sets the power Pc obtained by subtracting the power Pr required to restart the engine 2 from the dischargeable power Pd of the high-voltage battery 4 as the power that can be consumed by the voltage converter 5 when the engine 2 is restarted, thereby making it possible to prevent a shortage of power supplied to the electrical load 7 when the engine 2 is restarted.

[0042] In addition, the vehicle control device in this embodiment sets the power Pc, obtained by subtracting the power Pr required to restart the engine 2 from the dischargeable power Pd of the high-voltage battery 4, as the power that can be consumed by the voltage converter 5 when the engine 2 is restarted. Therefore, if the high-voltage battery 4 can output sufficient power, the electrical load 7 can continue to operate stably when the engine 2 is restarted.

[0043] In addition, the vehicle control device of this embodiment sets the power Pc obtained by subtracting the power Pr required to restart the engine 2 from the dischargeable power Pd of the high-voltage battery 4 as the power that can be consumed by the voltage converter 5 when restarting the engine 2, so that the power stored in the high-voltage battery 4 can be fully utilized and fuel efficiency during actual driving can be improved.

[0044] In addition, the vehicle control device of this embodiment implements output limitation of the voltage converter 5 when the restart conditions are met and releases the output limitation of the voltage converter 5 when the restart of the engine 2 is completed, thereby shortening the time during which the output of the voltage converter 5 is restricted.

[0045] In addition, the vehicle control device of this embodiment estimates the power Pr required to restart the engine 2 based on the friction at the time of restarting the engine 2, and therefore can execute output limitation of the voltage converter 5 without impairing the restartability of the engine 2.

[0046] In the above-described embodiment, the description of the drive system of the vehicle 1 has been omitted. However, the vehicle control device according to the present invention is applicable to hybrid vehicles such as parallel hybrid vehicles and series hybrid vehicles by changing the automatic stop conditions and restart conditions of the engine 2, in addition to idle stop vehicles using the engine 2 as a drive source.

[0047] In addition, in the present embodiment, an example has been described in which the ECU 8 estimates the electric power Pr required for restarting the engine 2 based on the friction at the time of restarting the engine 2. However, the ECU 8 may set the electric power Pr required for restarting the engine 2 to a constant that is experimentally determined in advance.

[0048] In addition, in this embodiment, when the SOC of the high-voltage battery 4 is less than the SOC at which the engine 2 can be restarted, the ECU 8 may control the voltage converter 5 to supply power to the motor 3 from the low-voltage battery 6.

[0049] By being configured in this manner, the vehicle control device of this embodiment can ensure the restartability of the engine 2 even when the SOC of the high-voltage battery 4 is below the SOC at which the engine 2 can be restarted.

[0050] While the present invention has been disclosed by way of example, it will be apparent that modifications may be made to the present invention without departing from the spirit and scope of the present invention, and the present invention is disclosed with the understanding that equivalents of such modifications are intended to be included within the scope of the invention as defined by the appended claims. [Explanation of symbols]

[0051] 1 vehicle 2 Engine 3 Motor (engine starter) 4 High voltage battery 5. Voltage converter 7 Electrical Load 30 Control section

Claims

1. A high voltage battery; an engine starting device that starts an engine using power supplied from the high voltage battery; a voltage converter that reduces the voltage of the power supplied from the high-voltage battery and outputs the reduced voltage; an electric load to which the output power of the voltage converter is supplied, A control device for a vehicle that automatically stops the engine when a predetermined automatic stop condition is satisfied, and restarts the automatically stopped engine when a predetermined restart condition is satisfied, A vehicle control device comprising: a control unit that executes output limitation to set the power that can be consumed by the voltage converter when restarting the engine to be the power that can be discharged from the high-voltage battery minus the power required to restart the engine.

2. The control unit is 2. The vehicle control device according to claim 1, wherein the output restriction is implemented when the predetermined restart condition is satisfied, and the output restriction is released when the engine restart is completed.

3. The control unit is 2. The vehicle control device according to claim 1, wherein the electric power required for restarting the engine is estimated based on the friction at the time of restarting the engine.

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