Vehicle control device

Abstract

To provide a control device for a vehicle capable of preventing early deterioration of a battery.SOLUTION: The ECU6 has a function of automatically stopping the engine 2 when a predetermined automatic stopping condition is satisfied, and restarting the engine 2 when a predetermined restarting condition is satisfied during the automatic stopping of the engine 2, and the ECU6 determines whether or not to charge the battery 4 by the power generator 3 according to a soak time of the engine 2 when the engine 2 is started by the ECU6.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 proposes a technology for a hybrid vehicle equipped with an internal combustion engine capable of outputting power for driving, an electric motor capable of cranking the internal combustion engine, and a storage means capable of exchanging electric power with the electric motor, the technology including: an input / output current detection means for detecting an input / output current, which is the current input to and output from the storage means; a terminal voltage detection means for detecting a terminal voltage, which is the voltage between the terminals of the storage means; a charging time setting means for setting a charging time that tends to be longer the greater the ratio of the time change in the detected terminal voltage to the time change in the input / output current detected when the internal combustion engine is started; and a control means for controlling the internal combustion engine and the electric motor to start the internal combustion engine when a command to start the internal combustion engine is given when the temperature of the storage means is below a predetermined temperature, and for controlling the internal combustion engine and the electric motor to charge the storage means for a set charging time after the internal combustion engine is started. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-100136 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the conventional technology described above, when the soak time of the internal combustion engine (hereinafter referred to as the "engine") is short, the battery temperature is high and the battery is in an active state, so battery deterioration or over-discharge may not be detected.

[0005] Furthermore, in the conventional technology, when the engine soak time is long, the battery temperature is low and the battery is in an inactive state, so that the deterioration or discharge of the battery may be detected excessively.

[0006] As such, conventional technologies have the problem that they are unable to detect battery deterioration or over-discharge, or may detect battery deterioration or over-discharge excessively, making it impossible to maintain the battery properly and causing the battery to deteriorate prematurely.

[0007] The present invention has been made to solve the above-mentioned problems, and has an object to provide a vehicle control device that can prevent early deterioration of a battery. [Means for solving the problem]

[0008] The vehicle control device of the present invention is a vehicle control device that controls a vehicle provided with an engine, a generator that generates electricity using the driving force of the engine, a battery that stores the electricity generated by the generator, a starter that starts the engine, and a control unit that automatically stops the engine when predetermined automatic stop conditions are met and restarts the engine when predetermined restart conditions are met while the engine is automatically stopped, and is configured to determine whether or not to charge the battery using the generator depending on the soak time of the engine when the engine is started by the starter. [Effects of the Invention]

[0009] The present invention can provide a vehicle control device that can prevent early deterioration of a battery. [Brief explanation of the drawings]

[0010] [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. [Figure 2]FIG. 2 is a flowchart showing the battery charge control operation of the vehicle control device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] A vehicle control device according to one embodiment of the present invention is a vehicle control device that controls a vehicle provided with an engine, a generator that generates electricity using driving force of the engine, a battery that stores the electricity generated by the generator, a starter that starts the engine, and a control unit that automatically stops the engine when predetermined automatic stop conditions are met and restarts the engine when predetermined restart conditions are met while the engine is automatically stopped, wherein when the engine is started by the starter, the control unit determines whether to charge the battery using the generator depending on the engine soak time. This makes it possible to prevent early deterioration of the battery. [Example]

[0012] A vehicle equipped with a vehicle control device according to an embodiment of the present invention will be described below with reference to the drawings.

[0013] As shown in FIG. 1, a vehicle 1 includes an engine 2, a generator 3, a battery 4, a starter 5, and an ECU (Electronic Control Unit) 6.

[0014] The engine 2 has a plurality of cylinders. In this embodiment, the engine 2 generates power to drive the vehicle 1 by performing a series of four strokes for each cylinder, which are an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke.

[0015] The generator 3 is provided so as to be interlocked with the crankshaft of the engine 2. In this embodiment, the generator 3 is configured by an ISG (Integrated Starter Generator).

[0016] The generator 3 converts the power generated by the engine 2 into electric power. The generator 3 is rotated by receiving electric power from the battery 4, thereby restarting the engine 2 that has automatically stopped.

[0017] The battery 4 is configured as a rechargeable secondary battery. The battery 4 stores the power generated by the generator 3 and supplies power to drive the generator 3 and electrical loads such as the starter 5. In this embodiment, the battery 4 is configured as a lead storage battery.

[0018] The starter 5 includes a motor and a pinion gear. The starter 5 rotates the motor using power supplied from the battery 4, thereby rotating the crankshaft of the engine 2 via the pinion gear, and providing the engine 2 with a rotational force at the time of starting.

[0019] The ECU 6 is composed of a computer unit equipped with a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory for storing backup data, input ports, and output ports.

[0020] 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 6. That is, the CPU executes the program stored in the ROM using the RAM as a work area, causing the computer unit to function as the ECU 6 in this embodiment.

[0021] Various sensors are connected to the input port of the ECU 6, including a battery sensor 21 that detects the charge / discharge current and terminal voltage of the battery 4, a vehicle speed sensor 23 that detects the vehicle speed, and a brake stroke sensor 24 that detects the amount of brake pedal operation (hereinafter simply referred to as the "brake stroke").

[0022] The output port of the ECU 6 is connected to various control objects including the generator 3, the starter 5, an injector 26 that injects fuel into the engine 2, and an ignition plug 27 that ignites in the combustion chamber of the engine 2. The ECU 6 controls the various control objects connected to the output port based on information obtained from various sensors connected to the input port.

[0023] The ECU 6 functions as a control unit 30 that automatically stops the engine 2 when predetermined automatic stop conditions are met, and restarts the engine 2 when predetermined restart conditions are met while the engine 2 is automatically stopped.

[0024] In this embodiment, when the engine 2 is in operation, the ECU 6 determines that the automatic stop condition is met when the vehicle speed detected by the vehicle speed sensor 23 is 0 and the brake stroke detected by the brake stroke sensor 24 is equal to or greater than a predetermined amount.

[0025] When it is determined that the automatic stop condition is met, the ECU 6 automatically stops the engine 2 by stopping the injection of fuel by the injector 26 and the ignition of the spark plug 27. When the brake stroke detected by the brake stroke sensor 24 becomes less than a predetermined amount while the engine 2 is automatically stopped, the ECU 6 determines that the restart condition is met.

[0026] When it is determined that the restart conditions are met, the ECU 6 causes the generator 3 to rotate the crankshaft of the engine 2, and then restarts the engine 2 by starting the supply of fuel by the injector 26 and the ignition of the spark plug 27.

[0027] When the engine 2 is started by the starter 5, the ECU 6 determines whether or not to charge the battery 4 by the generator 3 depending on the soak time from when the engine 2 is stopped until the engine 2 completely explodes. When the engine 2 is started by the starter 5, the ECU 6 makes the conditions for determining to charge the battery 4 stricter as the soak time of the engine 2 becomes longer.

[0028] Specifically, the ECU 6 measures the minimum value of the voltage between the terminals of the battery 4 while the engine 2 is being started by the starter 5 (hereinafter simply referred to as the "minimum voltage at start-up") from the detection value of the battery sensor 21. If the minimum voltage at start-up is less than a threshold value TH, the ECU 6 determines to charge the battery 4. The ECU 6 determines the threshold value TH, which decreases as the soak time of the engine 2 becomes longer.

[0029] In this embodiment, a threshold map in which the soak time and the threshold value TH are associated with each other is stored in the ROM of the ECU 6. The threshold map is set so that the threshold value TH decreases as the soak time increases.

[0030] The threshold map may associate the threshold value TH with the soak time in a stepwise manner, or may associate the threshold value TH with the soak time in a continuous manner. The ECU 6 refers to the threshold map and determines the threshold value TH according to the soak time.

[0031] When the ECU 6 determines to charge the battery 4, it determines the minimum charging time (hereinafter also simply referred to as "forced charging time") for charging the battery 4 according to the soak time of the engine 2. The ECU 6 determines the forced charging time so that it becomes longer as the engine soak time becomes longer.

[0032] In this embodiment, a forced charging time map in which soak times and forced charging times are associated with each other is stored in the ROM of the ECU 6. The forced charging time map is set so that the forced charging time increases as the soak time increases.

[0033] The forced charging time map may correspond to the soak time in a stepwise manner, or may correspond to the soak time in a continuous manner. The ECU 6 refers to the forced charging time map and determines the forced charging time according to the soak time.

[0034] The battery charge control operation performed by the ECU 6 configured as above will be described with reference to Fig. 2. The battery charge control operation described below is executed when the engine 2 is started by the starter 5.

[0035] First, in S1, the ECU 6 measures the minimum voltage at start-up during the period when the engine 2 is started by the starter 5. After executing the process of S1, the ECU 6 executes the process of S2.

[0036] In S2, the ECU 6 determines whether or not the engine 2 has completely exploded. If it is determined in S2 that the engine 2 has completely exploded, the ECU 6 executes the process of S3. If it is determined in S2 that the engine 2 has not completely exploded, the ECU 6 executes the process of S1. That is, if it is determined in S2 that the engine 2 has not completely exploded, the ECU 6 enters a state of waiting for the engine 2 to completely explode.

[0037] In S3, the ECU 6 calculates the soak time of the engine 2. The ECU 6 stores the time when the engine 2 stopped in a flash memory or the like, and calculates the soak time of the engine 2 by subtracting the stored time from the current time. After executing the process of S3, the ECU 6 executes the process of S4.

[0038] In S4, the ECU 6 prohibits automatic stop (hereinafter also simply referred to as "IS") of the engine 2. After executing the process of S4, the ECU 6 executes the process of S5. In S5, the ECU 6 determines the threshold value TH. After executing the process of S5, the ECU 6 executes the process of S6.

[0039] In S6, the ECU 6 determines whether the minimum voltage at startup is less than the threshold value TH. If it is determined in S6 that the minimum voltage at startup is less than the threshold value TH, the ECU 6 executes the process of S7. If it is determined in S6 that the minimum voltage at startup is not less than the threshold value TH, the ECU 6 executes the process of S11.

[0040] In S7, the ECU 6 determines the forced charging time. After executing the process of S7, the ECU 6 executes the process of S8. In S8, the ECU 6 determines the voltage of the electric power to be generated by the generator 3 (hereinafter also referred to as "generated voltage").

[0041] That is, after executing the process of S7, the ECU 6 starts charging the battery 4. In S8, the ECU 6 determines the power generation voltage based on the detection value of the battery sensor 21. After executing the process of S8, the ECU 6 executes the process of S9.

[0042] In S9, the ECU 6 determines whether the forced charging time has elapsed since executing the process of S7. If it is determined in S9 that the forced charging time has elapsed, the ECU 6 executes the process of S10. If it is determined in S9 that the forced charging time has not elapsed, the ECU 6 executes the process of S8. That is, the ECU 6 continues charging the battery 4 until it is determined in S9 that the forced charging time has elapsed.

[0043] In S10, the ECU 6 determines whether or not charging of the battery 4 is complete. For example, the ECU 6 determines that charging of the battery 4 is complete if the charging current of the battery 4 detected by the battery sensor 21 is substantially equal to or less than 0.

[0044] If it is determined in S10 that charging of the battery 4 is complete, the ECU 6 executes the process of S11. If it is determined in S10 that charging of the battery 4 is not complete, the ECU 6 executes the process of S10. That is, charging of the battery 4 continues until it is determined in S10 that charging of the battery 4 is complete.

[0045] In S11, the ECU 6 permits IS. After executing the process of S11, the ECU 6 ends the battery charge control operation.

[0046] As described above, when the engine 2 is started by the starter 5, the vehicle control device of this embodiment determines whether or not to charge the battery 4 depending on the soak time of the engine 2, thereby maintaining the battery 4 appropriately and preventing the battery 4 from deteriorating prematurely.

[0047] In addition, when the engine 2 is started by the starter 5, the vehicle control device of this embodiment tightens the conditions for deciding to charge the battery 4 as the soak time of the engine 2 becomes longer, so that it can appropriately decide whether to charge the battery 4 depending on the soak time of the engine 2.

[0048] In other words, when the soak time of the engine 2 is short, the vehicle control device of this embodiment relaxes the conditions for charging the battery 4, thereby appropriately detecting deterioration or over-discharge of the battery 4 and charging the battery, thereby preventing the battery 4 from deteriorating prematurely.

[0049] Furthermore, when the soak time of the engine 2 is long, the vehicle control device according to this embodiment tightens the conditions for determining to charge the battery 4, thereby preventing excessive detection of battery deterioration or discharge, and therefore reducing the frequency of charging the battery when the engine 2 is started by the starter 5. Therefore, the vehicle control device according to this embodiment can improve fuel efficiency by increasing the frequency of executing IS.

[0050] In addition, the vehicle control device of this embodiment determines a threshold value TH that decreases as the engine soak time becomes longer, so the conditions for deciding to charge the battery 4 can be made stricter as the soak time of the engine 2 becomes longer.

[0051] Furthermore, when the vehicle control device of this embodiment decides to charge the battery 4, it is possible to charge the battery 4 to a degree that allows reliable detection of deterioration or over-discharge of the battery 4 by determining the forced charging time according to the soak time of the engine 2.

[0052] In addition, the vehicle control device of this embodiment determines the forced charging time to be longer as the soak time of the engine 2 becomes longer, so that the forced charging time can be appropriately determined according to the soak time of the engine 2.

[0053] In this embodiment, an example has been described in which the generator 3 is configured by an ISG. However, the generator 3 may be configured by another generator such as an alternator or a motor generator.

[0054] In the present embodiment, the battery 4 is a lead storage battery, but the battery 4 may be a lithium ion battery or other secondary battery.

[0055] In addition, in this embodiment, an example has been described in which the ECU 6 determines the threshold value TH according to the soak time of the engine 2 based on the threshold value map. However, the ECU 6 may determine the threshold value TH according to the soak time of the engine 2 according to a predetermined arithmetic expression.

[0056] In addition, in the present embodiment, an example has been described in which the ECU 6 determines the threshold value TH in accordance with the soak time of the engine 2. However, the ECU 6 may determine the threshold value TH in accordance with the soak time of the engine 2 and the temperature of the battery 4.

[0057] Furthermore, the ECU 6 may estimate the soak time of the engine 2 from the temperature of the battery 4 when the engine 2 is stopped and the temperature of the battery 4 when the engine 2 is started. In other words, the ECU 6 may determine the threshold value TH according to the temperature of the battery 4 when the engine 2 is stopped and the temperature of the battery 4 when the engine 2 is started.

[0058] In the present embodiment, the example has been described in which the ECU 6 determines the forced charging time according to the soak time of the engine 2 based on the forced charging time map. However, the ECU 6 may determine the forced charging time according to the soak time of the engine 2 according to a predetermined calculation formula. The ECU 6 may also determine the forced charging time according to the temperature of the battery 4 when the engine 2 is stopped and the temperature of the battery 4 when the engine 2 is started.

[0059] While the present invention has been described with reference to an embodiment thereof, it will be apparent that modifications may be made thereto without departing from the scope of the present invention, and the present invention is disclosed with the understanding that equivalents of such modifications are intended to be encompassed within the scope of the appended claims. [Explanation of symbols]

[0060] 1 vehicle 2 engines 3. Generator 4 Battery 5 Starter 30 Control Unit

Claims

1. The engine and a generator that generates electricity using the driving force of the engine; a battery that stores the power generated by the generator; a starter for starting the engine; a control unit that automatically stops the engine when a predetermined automatic stop condition is met, and restarts the engine when a predetermined restart condition is met while the engine is automatically stopped, The control unit is configured to determine whether to charge the battery using the generator when the engine is started by the starter, based on the soak time of the engine.

2. 2. The vehicle control device according to claim 1, wherein, when the engine is started by the starter, the control unit makes the conditions for determining to charge the battery stricter as the soak time of the engine becomes longer.

3. The control unit determining a threshold that decreases as the engine soak time increases; If the minimum value of the voltage across the terminals of the battery during the period in which the engine is started by the starter is less than the threshold, it is determined that the battery is to be charged.

3. The vehicle control device according to claim 2.

4. 2. The vehicle control device according to claim 1, wherein, when the control unit determines to charge the battery, the control unit determines a minimum charging time for charging the battery in accordance with a soak time of the engine.

5. 5. The vehicle control device according to claim 4, wherein the control unit determines the minimum charging time for charging the battery so that the longer the soak time of the engine becomes, the longer the minimum charging time for charging the battery becomes.

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