JP5673578B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a vehicle control device applied to a vehicle that performs idle stop control.

  In recent years, an increase in environmental awareness has increased the number of vehicles that perform idle stop control that automatically stops and restarts an internal combustion engine when a predetermined condition is satisfied. In this type of vehicle, power is supplied to the air conditioner, car stereo, etc. while the internal combustion engine is stopped by a battery. In addition, considerable power is supplied from the battery to the starter when starting the internal combustion engine. Therefore, in city driving or the like that frequently stops and starts, the battery is repeatedly charged and discharged, and the battery is likely to deteriorate.

  By the way, when starting the internal combustion engine, since the generator is not generated, and the starter is operated only by the power supplied from the battery, the battery voltage temporarily decreases at the moment of starting the internal combustion engine. Occurs. In particular, when the battery is deteriorated or the temperature of the battery is low, the internal resistance of the battery is large and the amount of voltage drop is also large.

  If the voltage drop amount of the battery is too large, the voltage value of the battery may be lower than the minimum operating voltage value of the electronic control unit that controls the internal combustion engine. If this happens, the electronic control unit is reset, so that a signal cannot be transmitted to the internal combustion engine, and the internal combustion engine fails to start. Accordingly, it is necessary to detect whether or not the idle stop control can be executed by detecting the battery state, and to prohibit the execution of the idle stop control if it is determined that it is impossible. For example, in Patent Document 1, when the internal combustion engine is started, the minimum voltage value is measured to detect the battery state, and the minimum voltage value is compared with the determination value to determine whether or not the idle stop control can be executed. Is judged.

JP 2009-13953 A

  However, when starting the internal combustion engine by operating the ignition key of the driver, the minimum voltage value of the battery may not be measured when the internal combustion engine is started if the driver turns the ignition key quickly. When the internal combustion engine is started by operating the ignition key, the electronic control unit that executes the idle stop control is started when the ignition key is positioned at the ignition (IG). When the ignition key is located at the start, the internal combustion engine is started. Therefore, when the ignition key is quickly turned from IG to start, the internal combustion engine may be started before the completion of the start of the electronic control device (during startup). The voltage value of the battery becomes the minimum voltage value immediately after the start of the internal combustion engine. Therefore, if the start of the internal combustion engine is started before the start of the electronic control device, the minimum voltage value may not be measured after the minimum voltage value has already been generated when the start of the electronic control device is completed. As a result, it becomes impossible to determine whether or not the idle stop control can be executed.

  The same problem may occur not only when the driver turns the ignition key quickly, but also when the minimum voltage value of the battery cannot be measured when the internal combustion engine is started for some reason.

  The present invention has been made in view of the above circumstances, and whether or not the battery state is detected and the idle stop control is executed even when the minimum voltage value of the battery cannot be measured when the internal combustion engine is started. The main object is to provide a vehicle control device capable of determining the above.

  The present invention employs the following means in order to solve the above problems.

  The invention according to claim 1 is applied to a vehicle including an internal combustion engine, a battery, and a voltage sensor that measures the voltage of the battery, and automatically stops and restarts the engine when a predetermined condition is satisfied. A vehicle control device that executes idle stop control, wherein when the engine is started, the lowest voltage value that is the lowest voltage value of the battery cannot be measured by the voltage sensor. The minimum voltage value, which is the minimum value of the battery voltage after the measurement, is measured by the voltage sensor, and the minimum voltage value is compared with the first threshold value to determine whether or not to execute the idle stop control. .

  According to the above configuration, when the minimum voltage value of the battery cannot be measured, the minimum voltage value generated after the generation of the minimum voltage value is measured, the minimum voltage value is compared with the first threshold value, and the idle stop control is performed. It is determined whether or not to execute.

  The minimum voltage value of the battery is proportional to the rotational speed of the internal combustion engine. If the minimum voltage value is equal to or greater than a predetermined value, the start of the internal combustion engine can be completed. Therefore, the minimum voltage value is also a value indicating startability like the minimum voltage value, and therefore the minimum voltage value can be replaced with the minimum voltage value. In addition, there is a high possibility that the minimum voltage value generated after the minimum voltage value is generated can be measured even if the start-up of the electronic control device is delayed. Therefore, even when the minimum voltage value of the battery cannot be measured at the time of starting the internal combustion engine, it is possible to determine whether or not the idle stop control is executed by measuring the minimum voltage value and detecting the battery state.

The schematic diagram which shows schematic structure of the vehicle system which concerns on this embodiment. The time chart which shows the voltage fluctuation of the battery by engine starting. The figure which shows the relationship between minimum voltage value and engine speed. The flowchart which shows the process sequence which determines whether idle stop control is performed.

  Hereinafter, an embodiment embodied in a vehicle that uses an engine as a travel drive source and performs idle stop control will be described with reference to the drawings. The vehicle control device performs idle stop control for automatically stopping and restarting the engine. First, a schematic configuration of a vehicle system in which a vehicle control device is mounted will be described with reference to FIG.

  As shown in the figure, this vehicle has an engine (internal combustion engine) 10, a starter (motor) 12, an alternator (generator) 13, an auxiliary machine 14 such as a car stereo or an air conditioner, and an ignition key operated by a driver. An ignition switch 16 and a relay 22 are mounted.

  A starter 12 is connected to the crankshaft of the engine 10, and an alternator 13 is connected via connecting means such as a belt. The engine 10 performs fuel injection and ignites the fuel / air mixture in the combustion chamber to burn the mixture. The operation of the engine 10 is performed by an engine ECU 15 described later.

  The starter 12 is connected to the battery 11 via a relay 22. The starter 12 is driven at the time of start by a driver's ignition key operation and at the time of automatic restart by execution of idle stop control. In the case of starting by the driver operating the ignition key, when the ignition key reaches the start position, the start switch of the ignition switch 16 is closed and the relay 22 is energized. As a result, the relay circuit between the battery 11 and the starter 12 is closed, and power is supplied from the battery 11 to the starter 12. The starter 12 is driven by power supply and starts the engine 10. In the case of automatic restart by execution of idle stop control, the relay 22 is controlled by an idle stop ECU 18 described later when a predetermined condition is satisfied. As a result, the relay circuit between the battery 11 and the starter 12 is closed, and the starter 12 starts the engine 10. When the start switch of the ignition switch 16 is closed, a signal indicating that the starter 12 is being driven is transmitted to an engine ECU 15 described later and eventually to the idle stop ECU 18 by communication. When the ignition switch 16 and the idle stop ECU 18 are connected by hard wires, a signal that the starter 12 is being driven is directly taken into the idle stop ECU 18.

  The alternator 13 is connected to the crankshaft of the engine 10 via connecting means such as a belt, and is driven to generate electric power as the engine 10 rotates. The generated electric power is supplied to the battery 11 and the auxiliary machine 14.

  The auxiliary machine 14 receives power supply from the alternator 13 and the battery 11. Specifically, when the ignition key is moved to the ACC position by the driver's operation, the ACC switch of the ignition switch 16 is closed. Accordingly, the relay circuit between the battery 11 and the auxiliary machine 14 is closed, and electric power is supplied from the battery 11 to the auxiliary machine 14. Further, when the engine is stopped due to the execution of the idle stop control, the relay 22 is controlled by the idle stop ECU 18, and the relay circuit between the battery 11 and the auxiliary machine 14 is closed. Then, electric power is supplied from the battery 11 to the auxiliary machine 14.

  As the battery 11, for example, a 12V lead storage battery is employed. The battery 11 supplies power to the starter 12 and the auxiliary machine 14 as described above, and also supplies power to the engine ECU 15 and the idle stop ECU 18. The battery 11 includes a voltage sensor 17 that measures the voltage of the battery 11. The voltage value measured by the voltage sensor 17 is taken into the idle stop ECU 18.

  The ignition switch 16 is opened and closed according to the position of the ignition key. The ignition key is turned to OFF, ACC, IG, and start positions by the driver's operation. When the ignition key is in the ACC position, the ACC switch is closed. When the ignition key is in the IG position, an activation signal is transmitted to the engine ECU 15 and the idle stop ECU 18. Further, when the ignition key reaches the start position, the start switch is closed.

  The vehicle system also includes both an ECU (electronic control unit) of the engine ECU 15 and the idle stop ECU 18, a vehicle speed sensor 19 that detects the vehicle speed, a shift position sensor 20 that detects the position of the shift lever, and a brake that detects the depression of the brake. Various sensors of the sensor 21 are provided. Each ECU is mainly composed of a microcomputer including a central processing unit (CPU) and a storage device (ROM and RAM), and executes various control programs stored in the ROM. Each ECU receives and activates a signal when the ignition key is in the IG position by a driver's operation, and operates with electric power supplied from the battery 11. Further, detection values detected by various sensors are taken into the engine ECU 15 and then transmitted to the idle stop ECU 18. The engine ECU 15 and the idle stop ECU 18 can communicate with each other bidirectionally.

  The engine ECU 15 transmits a signal for driving the fuel injection system and the ignition system to the engine 10 when the engine 10 is manually operated by the driver and when the engine restart signal transmitted from the idle stop ECU 18 is received. . Further, the engine ECU 15 transmits a signal for stopping the fuel injection system and the ignition system to the engine 10 when the engine 10 is manually stopped by the driver and when the engine stop signal transmitted from the idle stop ECU 18 is received. To do.

  The idle stop ECU 18 determines whether or not to execute the idle stop control based on the minimum value or the minimum value of the voltage detected by the voltage sensor 17 when the engine 10 is started. If it is determined to be executed, it is determined whether the automatic stop condition and the automatic restart condition of the engine 10 are satisfied based on the detection values of the vehicle speed sensor 19, the shift position sensor 20, and the brake sensor 21. When it is determined that the automatic stop condition is satisfied, a stop signal is transmitted to the engine ECU 15. On the other hand, when it is determined that the automatic restart condition is satisfied, a restart signal is transmitted to the engine ECU 15. In the present embodiment, the idle stop ECU 18 corresponds to a vehicle control device. Hereinafter, determination of whether or not the idle stop control can be performed will be described.

  FIG. 2 shows the voltage fluctuation of the battery 11 when the engine 10 is started. Note that when the engine 10 is started, power generation by the alternator 13 is stopped, and power generation by the alternator 13 is started when the engine 10 is started. The period without the first voltage fluctuation is a stop period of the engine 10. When the starter 12 is energized, a large current (inrush current) flows through the starter 12 because no induced voltage is generated in the starter 12 that has not yet been stopped. As a result, the voltage of the battery 11 greatly decreases, and a minimum voltage value Ve that is the minimum value of the voltage of the battery 11 is generated. When the starter 12 rotates and compression of the piston provided in the engine 10 starts, the voltage of the battery 11 rises while repeating fluctuations up and down. At this time, a minimum voltage value Vc that is a minimum value of the voltage of the battery 11 is generated.

  In this case, the minimum voltage value Vc is the minimum value that occurs second after the minimum voltage value Ve is generated. The minimal value that occurs first remains affected by the inrush current and may not accurately indicate startability. In addition, the minimum value occurring after the third is large and difficult to detect, and may not occur if the engine 10 is started quickly.

  The minimum voltage value Ve is particularly low when the battery 11 is deteriorated and the internal resistance is large, when the temperature of the battery 11 is low and the internal resistance is large, and when the remaining capacity of the battery 11 is small. . In this case, the minimum voltage value Vc is also particularly low.

  If the minimum voltage value Ve becomes too low, the minimum voltage value Ve may fall below the minimum operating voltage of the engine ECU 15. If so, the engine ECU 15 may be reset and the engine 10 may fail to start. Therefore, the idle stop ECU 18 compares the minimum voltage value Ve with the second threshold value, and determines that the idle stop control is not performed when the minimum voltage value Ve is smaller than the second threshold value. The second threshold value is set to a predetermined minimum voltage value (for example, 7 V) that is determined to allow automatic restart after an automatic stop of engine 10 with some margin.

  In order to make the above determination, the voltage sensor 17 must measure the minimum voltage value Ve. When the start of the idle stop ECU 18 is completed before the starter 12 is energized (time point a), the minimum voltage value Ve can be measured. However, when the start of the idle stop ECU 18 is completed after the starter 12 is energized (time point b), the minimum voltage value Ve cannot be measured.

  Therefore, when the minimum voltage value Ve cannot be measured by the voltage sensor 17, the idle stop ECU 18 measures the minimum voltage value Vc generated after the minimum voltage value Ve is generated, and determines whether or not to execute the idle stop control. Determine.

  FIG. 3 is a diagram showing the relationship between the minimum voltage value Vc and the engine speed. Each point in the figure is obtained by changing the starting conditions of the engine 10 in various ways to obtain the relationship between the minimum voltage value Vc and the engine speed at each starting. As starting conditions, the environmental temperature is changed to normal temperature and low temperature, the deterioration degree of the battery 11 is changed to a plurality, and the remaining capacity of the battery 11 is changed to a plurality. As shown in FIG. 3, when the temperature is low, the minimum voltage value Vc required to obtain the same engine speed tends to be higher than when the temperature is normal. However, in both cases of normal temperature and low temperature, the higher the minimum voltage value Vc, the higher the engine speed at that time. Although various causes for the decrease in the minimum voltage value Vc are conceivable, even when the temperature is low, the start of the engine 10 can be completed if the minimum voltage value Vc is equal to or greater than the first threshold value. That is, regardless of the state of the battery 11, if the minimum voltage value Vc is equal to or greater than the first threshold value, the engine 10 can be started.

  Accordingly, when the minimum voltage value Ve cannot be measured by the voltage sensor 17, the idle stop ECU 18 compares the minimum voltage value Vc with the first threshold value. When the minimum voltage value Vc is smaller than the first threshold value, it is determined that the idle stop control is not performed. The first threshold value is set to a predetermined minimum voltage value (for example, 8 V) that is determined to allow automatic restart after automatic stop of engine 10 with some margin.

  Next, the detailed procedure of the process performed by the idle stop ECU 18 will be described with reference to FIG. The series of processes shown in the flowchart of FIG. 4 can be executed in a state where the activation of the idle stop ECU 18 is completed. This series of processing is performed both when the engine 10 is started manually by the driver and when the engine 10 is automatically restarted.

  First, in S1, it is determined whether or not the minimum voltage value Ve can be acquired when the engine 10 is started. Specifically, when the signal indicating that the starter 12 is being driven is not received, since the minimum voltage value Ve has not yet been generated, the minimum voltage value Ve can be acquired (YES) ). On the other hand, if the signal indicating that the starter 12 is being driven has already been received, the minimum voltage value Ve has already been generated, so it is determined that the minimum voltage value Ve cannot be acquired (NO). When it is determined that the minimum voltage value Ve can be acquired (YES), the process proceeds to S2. On the other hand, if it is determined that the minimum voltage value Ve cannot be acquired (NO), the process proceeds to S3.

  In S2, the minimum voltage value Ve is measured by the voltage sensor 17, and the minimum voltage value Ve is compared with the second threshold value. When the minimum voltage value Ve can be acquired, the determination is performed using the minimum voltage value Ve preferentially over the minimum voltage value Vc. If the minimum voltage value Ve is greater than or equal to the second threshold (YES), the process proceeds to S4. When the minimum voltage value Ve is smaller than the second threshold value (NO), the process proceeds to S5.

  In S3, the voltage sensor 17 measures the minimum voltage value Vc (second minimum value), and compares the minimum voltage value Vc with the first threshold value. Here, since the minimum voltage value Ve has not been acquired, the determination is performed using the minimum voltage value Vc instead of the minimum voltage value Ve. When the minimum voltage value Vc is greater than or equal to the first threshold (YES), the process proceeds to S4. When the minimum voltage value Vc is smaller than the first threshold (NO), the process proceeds to S5.

  Next, when the minimum voltage value Ve is equal to or greater than the second threshold value, or when the minimum voltage value Vc is equal to or greater than the first threshold value, it is determined in S4 that automatic restart after automatic stop is possible. Therefore, it is determined that the idle stop control is executed.

  Thereafter, in another routine, it is determined whether or not an automatic stop condition for the engine 10 is satisfied based on detection values of the vehicle speed sensor 19, the shift position sensor 20, and the brake sensor 21. When it is determined that the automatic stop condition is satisfied, a signal for stopping the engine 10 is transmitted to the engine ECU 15.

  On the other hand, if the minimum voltage value Ve is smaller than the second threshold value, or if the minimum voltage value Vc is smaller than the first threshold value, it is determined in S5 that automatic restart after automatic stop is impossible. Therefore, it is determined that the idle stop control is not executed. In this case, the execution of the idle stop control is prohibited over one trip of the vehicle.

  The present embodiment described above has the following effects.

  If the minimum voltage value Ve is not acquired, the minimum voltage value Vc generated after the generation of the minimum voltage value Ve is acquired, and the minimum voltage value Vc is compared with the first threshold value to execute idle stop control. It is determined whether or not.

  Similarly to the minimum voltage value Ve, the minimum voltage value Vc is a value indicating startability, and therefore the minimum voltage value Ve can be replaced with the minimum voltage value Vc. Further, there is a high possibility that the minimum voltage value Vc generated after the minimum voltage value Ve is generated can be acquired even when the activation of the idle stop ECU 18 is delayed. Therefore, even when the minimum voltage value Ve cannot be acquired when the engine 10 is started, it is possible to acquire the minimum voltage value Vc, detect the state of the battery 11, and determine whether or not to execute the idle stop control.

  The minimum voltage value Vc is the minimum value that occurs second after the minimum voltage value Ve is generated, so that the state of the battery 11 can be detected with high accuracy.

  When the lowest voltage value Ve is acquired when the engine 10 is started, the low voltage value Ve is compared with the second threshold value to preferentially determine whether or not to execute the idle stop control. Since the minimum voltage value Ve appears as a sharp peak when the engine 10 is started, it can be detected with high accuracy. Therefore, the state of the battery 11 can be determined with higher accuracy by using the lowest voltage value Ve with priority.

  If it is determined not to execute the idle stop control, the execution of the idle stop control is prohibited over one trip of the vehicle. Thereby, the remaining capacity of the battery 11 can be increased.

  The present invention is not limited to the above-described embodiment, and can be implemented as follows, for example.

  Although the accuracy is lower than that in the above embodiment, the first minimum value or the third minimum value may be a minimum voltage value to be compared with the first threshold value.

  -In above-mentioned embodiment, after it determines with not performing idle stop control in S5, execution of idle stop control is prohibited over 1 trip of this vehicle. However, when the battery 11 is charged and the battery 11 is fully charged, the execution of the idle stop control may be permitted. If it does in this way, when it charges and the battery 11 recovers, idle stop control can be performed.

  A crank sensor for detecting the rotational speed may be provided on the crankshaft, and it may be determined that the starter 12 is rotating based on the rotational speed detected by the crank sensor.

  DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... Battery, 12 ... Starter, 13 ... Alternator, 14 ... Auxiliary machine, 15 ... Engine ECU, 17 ... Voltage sensor, 18 ... Idle stop ECU

Claims (4)

Applied to a vehicle including an internal combustion engine (10), a battery (11), and a voltage sensor (17) for measuring the voltage of the battery, and automatically stops and restarts the engine when a predetermined condition is satisfied A vehicle control device (18) for executing idle stop control,
At the time of starting the engine, if the minimum voltage value that is the minimum value of the battery voltage cannot be measured by the voltage sensor, the minimum voltage that is the minimum value of the battery voltage after the minimum voltage value is generated A vehicle control device characterized in that a value is measured by the voltage sensor and the minimum voltage value is compared with a first threshold value to determine whether or not to execute the idle stop control.   The vehicle control device according to claim 1, wherein the minimum voltage value is a minimum value generated second after the minimum voltage value is generated.   When starting the engine, if the minimum voltage value can be measured by the voltage sensor, the minimum voltage value is compared with a second threshold value to preferentially determine whether or not to execute the idle stop control. The vehicle control device according to claim 1 or 2.   The vehicle control device according to any one of claims 1 to 3, wherein when it is determined that the idle stop control is not executed, the idle stop control is prohibited from being executed over one trip of the vehicle.

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