Control device for vehicle

Abstract

To provide a control device for a vehicle capable of stopping or permitting idling stop control without using an SOC sensor.SOLUTION: A control device for an internal combustion engine includes: an engine control section that executes idling stop control; an SOC estimation section that estimates a battery SOC on the basis of start time voltage of a battery for supplying electric power to a starter motor for starting the engine and a start time battery temperature; a stop section that stops the idling stop control when the start time voltage is less than a voltage threshold value required for starting the engine; a temperature estimation section that estimates a correspondence temperature of the battery corresponding to the voltage threshold value in the estimated SOC during stop of the idling stop control; a power generation control section that controls power generation electric power of an alternator for charging the battery so as to suppress lowering of SOC during stop of the idling stop control; and a permission section that permits the idling stop control when the temperature of the battery during stop of the idling stop control is higher than the correspondence temperature.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] The engine is started by a starter motor. The starter motor is supplied with power from a battery. Here, if the SOC (State of Charge) of the battery is low, there is a risk that the engine cannot be started by the idling stop control. For this reason, there is a technique for stopping or permitting the idling stop control based on the SOC of the battery (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-115568 A Summary of the Invention [Problem to be solved by the invention]

[0004] In order to stop or permit the idling stop control as in the above technology, a SOC sensor that detects the SOC of the battery is required. The use of the SOC sensor may increase the manufacturing cost of the vehicle.

[0005] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a vehicle control device that can stop or permit idling stop control without using a SOC sensor. [Means for solving the problem]

[0006] The above object can be achieved by a vehicle control device including an engine control unit that executes idling stop control to automatically stop and start an engine, a SOC estimation unit that estimates a State of Charge (SOC) of the battery based on a start-up voltage that is the voltage of a battery that supplies power to a starter motor that starts the engine at the time the engine is started and a start-up temperature that is the temperature of the battery at the time the engine is started, a stopping unit that stops the idling stop control when the start-up voltage is less than a voltage threshold required for starting the engine by the idling stop control, a temperature estimation unit that estimates a corresponding temperature of the battery that corresponds to the voltage threshold in the estimated SOC while the idling stop control is stopped, a power generation control unit that controls the power generation of an alternator that charges the battery so as to suppress a decrease in the SOC while the idling stop control is stopped, and a permission unit that permits the idling stop control when the temperature of the battery while the idling stop control is stopped is higher than the corresponding temperature. Effect of the Invention

[0007] According to the present invention, it is possible to provide a vehicle control device that can stop or permit idling stop control without using a SOC sensor. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of a vehicle according to an embodiment of the present invention; [Diagram 2] 4 is a flowchart illustrating an idling stop permission control executed by an ECU. [Diagram 3] This is a map that defines the relationship between the battery's starting voltage, starting temperature, and SOC. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Vehicle outline] FIG. 1 is a schematic diagram of a vehicle 1 of this embodiment. In FIG. 1, the vehicle 1 includes an engine 10, a starter motor 12, an alternator 14, a torque converter 20, an automatic transmission 22, a propeller shaft 26, an axle 30, driving wheels 32, a battery 40, and an ECU (Electronic Control Unit) 50. The engine 10 is a gasoline engine or a diesel engine that is a driving force source for traveling. The torque converter 20 is a fluid-type transmission device connected to the engine 10. The automatic transmission 22 is connected to the torque converter 20. Power from the engine 10 is transmitted to the automatic transmission 22 via the torque converter 20. The propeller shaft 26 is connected to an output shaft 24 of the automatic transmission 22. The differential gear device 28 is connected to the propeller shaft 26. The driving wheels 32 are connected to the differential gear device 28 via the axle 30.

[0010] The starter motor 12 cranks the engine 10 when it is started. The alternator 14 is a generator that converts part of the rotational power of the engine 10 into electric power. The battery 40 supplies electric power to the starter motor 12. The electric power generated by the alternator 14 is charged into the battery 40.

[0011] The ECU 50 is an electronic control unit including a calculation processing circuit that performs various calculation processes related to the driving control of the vehicle 1, and a memory that stores control programs and data. The ECU 50 is an example of a vehicle control device, and functionally realizes an engine control unit, a SOC estimation unit, a stop unit, a power generation control unit, and a permission unit, which will be described in detail later.

[0012] A sensor group 60 consisting of a plurality of sensors is electrically connected to the ECU 50. The sensor group 60 includes an accelerator pedal position sensor, a battery voltage sensor, and a battery temperature sensor. The accelerator pedal position sensor detects the position of the accelerator pedal. The battery voltage sensor detects the voltage of the battery 40. The battery temperature sensor detects the temperature of the battery 40.

[0013] The ECU 50 executes idling stop control. The idling stop control is a control for automatically suspending the engine 10 when a predetermined stop condition is satisfied, and then automatically starting the engine 10 when a predetermined start condition is satisfied. At the time of starting, the ECU 50 cranks the engine by the starter motor 12 and starts the engine 10 by controlling fuel injection and ignition. The stop condition is, for example, that the accelerator is off, that the vehicle speed is equal to or lower than a predetermined value, that the brake pedal is depressed, and that the temperature of the engine coolant is equal to or higher than a predetermined value. When all of these conditions are satisfied, the stop condition is said to be satisfied. In addition, the start condition is, for example, when the above stop condition is not satisfied, that is, when any one of the above conditions constituting the stop condition is not satisfied.

[0014] [Idling stop permission control] 2 is a flowchart illustrating the idling stop permission control executed by the ECU 50. This control is repeatedly executed while the ignition is on. The ECU 50 starts the engine 10 by the stator motor 12 (step S1). Next, the ECU 50 obtains the minimum voltage of the battery 40 when the engine 10 is started (hereinafter referred to as the starting voltage) and the temperature of the battery 40 (hereinafter referred to as the starting temperature) (step S2). The reason why the starting voltage is set to the minimum voltage of the battery 40 is because the voltage of the battery 40 temporarily drops due to the supply of power from the battery 40 to the stator motor 12.

[0015] 3, which defines the start-up voltage, start-up temperature, and SOC of the battery 40, to estimate the SOC of the battery 40 when the engine 10 is started (step S3). Step S3 is an example of a process executed by the SOC estimation unit.

[0016] FIG. 3 is a map that specifies the relationship between the starting voltage, starting temperature, and SOC of the battery 40. The vertical axis indicates the starting voltage, and the horizontal axis indicates the starting temperature. The higher the SOC, the higher the starting voltage relative to the starting temperature. The map in FIG. 3 shows a voltage threshold value that is the starting voltage required to start the engine 10 by idling stop control. The map in FIG. 3 is stored in a ROM in advance. The map in FIG. 3 illustrates the relationship between the starting voltage and the starting temperature at each of high SOC, medium SOC, and low SOC. For example, it is assumed that the state of the battery 40 is located at point P1 on the medium SOC based on the starting voltage and the starting temperature.

[0017] Next, the ECU 50 determines whether the starting voltage is less than the above-mentioned voltage threshold value (step S4). If the result in step S4 is No, the starting voltage is considered to satisfy the voltage required to start the engine 10 by the next idling stop control. In this case, this control ends.

[0018] If the answer is Yes in step S4, the starting voltage is deemed to be insufficient for the voltage required to start the engine 10 by the next idle stop control. The starting voltage at point P1 shown in FIG. 3 is less than the voltage threshold. In this case, the ECU 50 stops the idle stop control (step S5). This is to prevent the voltage of the battery 40 from being insufficient and causing the engine 10 to be unable to start when the engine 10 is started by the next idle stop control. Therefore, while the idle stop control is stopped, the engine 10 is not automatically stopped and is in a constantly running state. Step S5 is an example of a process executed by the stop unit.

[0019] Next, the ECU 50 estimates a temperature (hereinafter referred to as the corresponding temperature) corresponding to the above-mentioned voltage threshold value in the SOC estimated in step S3 (step S6). In the example of FIG. 3, the start-up temperature at the intersection of the curve of the medium SOC at point P1 and the line of the voltage threshold value corresponds to the corresponding temperature. That is, the estimated SOC is used to estimate the corresponding temperature corresponding to the voltage threshold value. Step S6 is an example of a process executed by the temperature estimation unit.

[0020] Next, the ECU 50 issues a power generation instruction to the alternator 14 so that the SOC of the battery 40 does not decrease (step S7). In detail, the power generation request instruction value that the ECU 50 issues to the alternator 14 is set to a value that does not discharge the battery 40 or more. This prevents the SOC from decreasing while the idling stop control is stopped. For example, in the example of FIG. 3, a medium SOC is maintained. Step S7 is an example of a process executed by the power generation control unit.

[0021] Next, the ECU 50 acquires the temperature of the battery 40 (step S8). The ECU 50 determines whether the battery temperature is higher than the corresponding temperature (step S9). If the answer is No in step S9, the ECU 50 executes step S7 again. If the answer is Yes in step S9, the ECU 50 assumes that the voltage of the battery 40 required for starting the engine 10 by the next idling stop control is secured, and permits the idling stop control (step S10). For example, in the example of FIG. 3, while the engine 10 is running, the temperature of the battery 40 rises, moving point P1 to point P2, and the temperature of the battery 40 becomes higher than the corresponding temperature. This permits the idling stop control.

[0022] Incidentally, while the idling stop control is stopped based on the voltage of the battery 40, the idling stop control is permitted based on the temperature of the battery 40. The reason for this is as follows. While the idling stop control is stopped, the engine 10 is in operation and is not in a state in which the voltage of the battery 40 temporarily drops due to the starter motor 12 being driven as occurs when the engine 10 is started. For this reason, if the idling stop control during the stop is permitted based on the voltage of the battery 40 being equal to or higher than the above-mentioned voltage threshold while the engine 10 is in operation, there is a risk that the start-time voltage in the next idling stop control will fall below the voltage threshold and the idling stop control will be stopped again. Step S10 is an example of a process executed by the permission unit.

[0023] As described above, the idling stop control is stopped or permitted without using an SOC sensor that detects the SOC of the battery 40. Since the vehicle 1 does not require an SOC sensor in this manner, the manufacturing costs of the vehicle 1 are reduced.

[0024] In step S7, the ECU 50 may issue a power generation instruction to the alternator 14 so as to increase the SOC of the battery 40. In this case, the actual SOC becomes higher than the SOC estimated in step S3, but if the determination in step S9 is Yes, the actual voltage is higher than the voltage threshold, so there is no problem even if the idling stop control is permitted.

[0025] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0026] 1 vehicle 10 Engine 12 Starter motor 14 Alternator 40 Battery 50 ECU (vehicle control device, engine control unit, SOC estimation unit, stop unit, power generation control unit, permission unit)

Claims

[Claim 1] an engine control unit that executes an idling stop control for automatically stopping and starting the engine; an SOC estimation unit that estimates a state of charge (SOC) of the battery based on a start-up voltage, which is a voltage of a battery that supplies power to a starter motor that starts the engine, at the time of starting the engine, and a start-up temperature, which is a temperature of the battery at the time of starting the engine; a stop unit that stops the idling stop control when the start-time voltage is less than a voltage threshold required for starting the engine by the idling stop control; a temperature estimation unit that estimates a corresponding temperature of the battery corresponding to the voltage threshold value at the estimated SOC while the idling stop control is stopped; a power generation control unit that controls a power generation amount of an alternator that charges the battery so as to suppress a decrease in the SOC while the idling stop control is stopped; and a permission unit that permits the idling stop control when a temperature of the battery while the idling stop control is stopped is higher than the corresponding temperature.

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