JP2011174415A - Idling stop device and method of charging battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique capable of raising the voltage of a battery by detecting the voltage drop of the battery even after a microcomputer is reset. <P>SOLUTION: In this idling stop device 1, the microcomputer 2 is reset when the voltage of the battery 51 is lowered and the voltage VCC of the power supply of the microcomputer 2 is less than the minimum operating voltage Vt of the microcomputer 2. The information of the voltage drop is stored in a storage part 3. Consequently, after the reset, the microcomputer 2 can detect that the voltage of the battery 51 is lowered based on the information of the voltage drop, and then can raise the voltage of the battery 51 by increasing the power generation amount of an alternator 52 for charging the battery 51. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an idling stop technique for automatically stopping / starting a vehicle engine.

  In recent years, an idling stop device for automatically stopping / starting a vehicle engine while a vehicle is stopped for a relatively short time such as waiting for a signal has been put into practical use for the purpose of saving fuel and exhaust gas. In a vehicle equipped with an idling stop device, the engine is automatically stopped when a stop condition such as when the brake is stepped on from a running state and the engine is stopped, and the start condition is such that the brake is released while the engine is stopped. When the above is established, the engine is automatically started (see, for example, Patent Document 1).

JP 2009-13953 A

  Electric power for driving a starter motor for starting the engine of the vehicle is supplied from a battery provided in the vehicle. Since the power required by the starter motor to start the engine is very large, if the engine is stopped / started by the idling stop function when the battery voltage is low, the battery voltage further decreases. The engine may not be able to start. Therefore, when the battery is deteriorated and its voltage is reduced, a measure for increasing the battery voltage is required.

  As described above, since the power required by the starter motor for starting the engine is very large, the voltage of the battery greatly decreases when the engine is started. For this reason, for example, the microcomputer provided in the idling stop device monitors the voltage of the battery at the time of starting the engine, and if the voltage of the battery falls below a predetermined threshold, the voltage of the battery is thereafter set. It is conceivable to configure the measures to raise.

  However, since the electric power for operating the microcomputer is also supplied from the battery, when starting the engine, if the voltage of the battery drops significantly below the voltage at which the microcomputer can operate, the microcomputer itself It cannot be operated and is reset. The microcomputer reset and restarted in this manner cannot grasp the cause of the reset and the voltage of the battery before the reset. The microcomputer is reset not only when the voltage of the power supply is reduced, but also when, for example, a runaway state occurs, but the cause of such a reset cannot be grasped.

  For this reason, even when the battery voltage is greatly lowered and reset, the microcomputer after resetting repeatedly stops / starts the engine by the idling stop function without executing a measure for increasing the battery voltage. End up. As a result, there is a possibility that the engine cannot be finally started.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a technology capable of grasping the battery voltage drop and increasing the battery voltage even after the microcomputer is reset.

  In order to solve the above-mentioned problem, the invention of claim 1 is an idling stop device that is mounted on a vehicle and automatically stops / starts the engine of the vehicle, and automatically activates the engine when a predetermined stop condition is satisfied. And a microcomputer having an idling stop function for automatically starting the engine when a predetermined start condition is satisfied while the engine is stopped, and the microcomputer obtained by stepping down the voltage of the battery of the vehicle Detection means for detecting that the voltage of the power source of the computer is less than the minimum operating voltage of the microcomputer, and the voltage regardless of the state of the microcomputer when the voltage of the power source is less than the minimum operating voltage. Storage means for storing the drop information, and when the voltage drop information is stored in the storage means. Has and a instruction means for instructing to increase the power generation amount of a generator to charge the battery.

  According to a second aspect of the present invention, in the idling stop device according to the first aspect, the microcomputer invalidates the idling stop function when the voltage drop information is stored in the storage means.

  According to a third aspect of the present invention, the engine of the vehicle is automatically stopped when a predetermined stop condition is satisfied, and the engine is automatically started when a predetermined start condition is satisfied while the engine is stopped. A method of charging a battery in a vehicle equipped with a microcomputer having an idling stop function, wherein the power supply voltage of the microcomputer obtained by stepping down the voltage of the vehicle battery is less than the minimum operating voltage of the microcomputer. The step of detecting that the voltage of the power source is less than the minimum operating voltage, the step of storing voltage drop information in the storage means regardless of the state of the microcomputer, and the storage means If voltage drop information is stored, increase the power generation amount of the generator that charges the battery. It includes a Shimesuru step.

  According to the first to third aspects of the present invention, when the voltage of the power source of the microcomputer becomes less than the minimum operating voltage of the microcomputer, the voltage drop information is stored in the storage means even if the microcomputer is reset. For this reason, the microcomputer after reset can grasp | ascertain the voltage drop of a battery based on voltage drop information, and can raise the voltage of a battery by raising the electric power generation amount of the generator which charges a battery.

  In particular, according to the invention of claim 2, by invalidating the idling stop function, the battery can be charged with the power generation amount increased even in the idling state, and the battery voltage can be effectively increased. it can.

FIG. 1 is a block diagram showing a configuration of an idling stop device. FIG. 2 is a diagram illustrating a processing flow of the idling stop device according to the first embodiment. FIG. 3 is a diagram illustrating changes in various signals when the battery voltage decreases. FIG. 4 is a diagram illustrating a processing flow of the idling stop device according to the second embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<1. First Embodiment>
<1-1. Configuration>
FIG. 1 is a block diagram showing a configuration of an idling stop device 1 and its peripheral elements according to the first embodiment. The idling stop device 1 is mounted on a vehicle such as an automobile, for example, and has a function of automatically stopping / starting an engine 57 included in the vehicle while the vehicle is stopped for a relatively short time such as waiting for a signal. .

  A vehicle on which the idling stop device 1 is mounted includes a battery 51 that supplies electric power to an electric load of each part of the vehicle. A power line 91 is connected to the battery 51, and an ignition switch 92 that can be operated by the user is provided on the power line 91. When the ignition switch 92 is turned on, power is supplied from the battery 51 to the idling stop device 1 via the power line 91. In addition, when the ignition switch 92 is turned on, power is supplied from the battery 51 via the power supply line 91 to various electric loads mounted on the vehicle.

  The battery 51 is charged by an alternator 52 that is a generator. Alternator 52 converts mechanical kinetic energy transmitted from engine 57 into alternating current power, and further rectifies it into direct current power with a rectifier including a diode. The generated power is stored in the battery 51 via the power line 91. When the alternator 52 generates power, a target voltage that is a target of power generation is set, and the alternator 52 generates power so that the voltage of the power supply line 91 becomes the target voltage.

  The idling stop device 1 is configured as an ECU (Electronic Control Unit) and includes a microcomputer 2 as a main component. The microcomputer 2 includes a CPU 21, a RAM 22, and a ROM 23. Various functions provided in the microcomputer 2 are realized by the CPU 21 performing arithmetic processing according to a program recorded in advance in the ROM 23. The functions of the microcomputer 2 include an idling stop function and a target voltage changing function for changing the target voltage of the alternator 52.

  The idling stop function is a function for automatically stopping / starting the engine 57 of the vehicle according to the traveling state of the vehicle. A signal indicating the running state of the vehicle is input to the microcomputer 2 via the interface 18 from various sensors provided in the vehicle. Specifically, vehicle speed is input from the vehicle speed sensor, shift lever position from the shift sensor, accelerator operation content from the accelerator sensor, and brake operation content from the brake sensor.

  When a predetermined stop condition is established based on signals indicating these running states, the engine 57 is stopped by the idling stop function. For example, when all the conditions “vehicle speed is 0”, “shift lever is“ D ”or“ N ””, “no accelerator operation”, and “with brake operation” are all satisfied, Is determined to have been established.

  When the engine 57 is stopped by the idling stop function, the microcomputer 2 transmits a predetermined stop signal to the engine ECU 56 that controls the engine 57. The engine ECU 56 stops the engine 57 in response to this signal.

  Further, when the engine 57 is stopped by the idling stop function and the predetermined start condition is established based on the signal indicating the running state, the engine 57 is automatically started by the idling stop function. For example, the start condition is determined to be satisfied when all of the conditions “shift lever is“ D ””, “accelerator operated”, and “brake not operated” are all satisfied.

  When the engine 57 is started with the idling stop function, the microcomputer 2 transmits a predetermined start signal to the starter control circuit 16 provided in the idling stop device 1. The starter control circuit 16 energizes the relay coil 53 in response to this signal. By energizing the relay coil 53, the relay switch 54 connected to the starter motor 55 that starts the engine 57 of the vehicle is turned on. Thereby, electric power is supplied from the battery 51 to the starter motor 55, the starter motor 55 is driven, and the engine 57 is started. The relay coil 53 is also energized by turning on a start switch 93 that can be operated by the user. When the user gets into the vehicle, the starter motor 55 is driven in response to the operation of the start switch 93, and the engine 57 is started.

  The idling stop device 1 also includes a regulator 11 that steps down the input voltage to a constant voltage as a power supply circuit to the microcomputer 2. For example, the regulator 11 is configured by combining a switching regulator and a series regulator.

  The power of the microcomputer 2 is supplied from the battery 51 of the vehicle. The ideal value of the voltage of the power supply of the microcomputer 2 is, for example, 5V, while the normal voltage of the battery 51 is, for example, 12V. Therefore, in the idling stop device 1, the voltage BATT of the battery 51 is stepped down by the regulator 11 to obtain the voltage VCC of the power source of the microcomputer 2.

  Note that the regulator 11 adjusts the output voltage within a range where the input voltage is the upper limit. If the input voltage falls below the target voltage that should be constant, the output voltage of the regulator 11 also falls below the target voltage. It will be. Therefore, when the battery 51 is deteriorated, if the battery voltage BATT is lowered, the voltage VCC of the power source of the microcomputer 2 obtained by stepping down by the regulator 11 is also lowered accordingly.

  The idling stop device 1 includes a voltage drop detection unit 13, a reset unit 14, and a runaway detection unit 15 as a circuit for resetting the microcomputer 2.

  The reduced voltage detection unit 13 is connected to a power supply line from the regulator 11 to the microcomputer 2 and monitors the voltage VCC of the power supply of the microcomputer 2. When the voltage VCC of the power source of the microcomputer 2 becomes lower than the minimum operating voltage at which the microcomputer 2 can operate (hereinafter, the symbol “Vt” is used), it indicates that the reset unit 14 should be reset. An instruction signal is output. The minimum operating voltage Vt of the microcomputer 2 is, for example, 3.9V. The reduced voltage detection unit 13 is constituted by, for example, a comparator that compares the voltage VCC with the minimum operating voltage Vt.

  The runaway detection unit 15 detects whether the microcomputer 2 is in a runaway state such as freezing. For example, the runaway detection unit 15 monitors an operation signal of a watchdog timer of the microcomputer 2 and determines that the microcomputer 2 is in a runaway state when a regular signal is not detected. In the runaway state, the microcomputer 2 cannot recover its function unless it is reset. For this reason, the runaway detection unit 15 outputs an instruction signal indicating that the reset unit 14 should be reset.

  The reset unit 14 outputs a reset signal that instructs the microcomputer 2 to reset. The reset signal is normally “H” and becomes “L” to instruct the microcomputer 2 to reset. The reset unit 14 sets the reset signal to “L” when an instruction signal indicating that the reset is to be performed from either the voltage drop detection unit 13 or the runaway detection unit 15. The microcomputer 2 constantly monitors this reset signal, and resets when the reset signal becomes “L”. That is, the microcomputer 2 is restarted after being temporarily stopped.

  The idling stop device 1 provides information indicating that the voltage VCC is less than the minimum operating voltage Vt when the voltage VCC of the power source of the microcomputer 2 is less than the minimum operating voltage Vt (hereinafter referred to as “voltage drop information”). .) Is stored. The instruction signal output from the reduced voltage detection unit 13 is also input to the storage unit 3. That is, when the voltage VCC of the power source of the microcomputer 2 becomes less than the minimum operating voltage Vt, the storage unit 3 is notified by an instruction signal, and the voltage drop information is stored in the storage unit 3 in response thereto. It will be.

  The storage unit 3 is configured by, for example, a flip-flop that is a logic circuit capable of storing 1-bit information. The minimum operating voltage of the storage unit 3 is lower than the minimum operating voltage Vt (eg, 3.6V) of the microcomputer 2 and is, for example, 1.6V. That is, even if the power supply voltage becomes lower than the minimum operating voltage Vt of the microcomputer 2, the storage unit 3 can hold the stored contents. For this reason, the memory | storage part 3 can memorize | store voltage drop information during reset of the microcomputer 2 irrespective of the state of the microcomputer 2. FIG.

  When the voltage of the battery 51 decreases and the voltage VCC becomes lower than the minimum operating voltage Vt, the microcomputer 2 is reset, while the storage unit 3 stores the voltage decrease information. Based on the fact that the voltage drop information is stored in the storage unit 3, the microcomputer 2 after the reset can grasp that the power supply voltage VCC has become less than the minimum operating voltage Vt before the reset. Become.

  For this reason, when the voltage drop information is stored in the storage unit 3, the reset microcomputer 2 executes a measure for increasing the voltage of the battery 51 so that the idling stop function can be maintained. Specifically, the microcomputer 2 raises the target voltage of the alternator 52 higher than usual by the target voltage changing function.

  The phenomenon that the voltage of the battery 51 greatly decreases occurs when the engine 57 is started because the power required by the starter motor 55 is very large. Hereinafter, when the engine 57 is started in this manner, a process in the case where the voltage of the battery 51 greatly decreases and the microcomputer 2 is reset will be described in detail.

<1-2. Processing>
FIG. 2 is a diagram showing a processing flow of the idling stop device 1 related to the resetting of the microcomputer 2.

  First, it is determined whether or not a condition for resetting the microcomputer 2 is satisfied. Specifically, the reduced voltage detection unit 13 determines whether the voltage VCC of the power source of the microcomputer 2 is less than the minimum operating voltage Vt of the microcomputer 2 (step S11). At the same time, the runaway detection unit 15 determines whether the microcomputer 2 is in a runaway state (step S12). If voltage VCC is equal to or higher than minimum operating voltage Vt (No in step S11) and microcomputer 2 is not in a runaway state (No in step S12), the process ends.

  When the voltage VCC of the power source of the microcomputer 2 becomes less than the minimum operating voltage Vt (Yes in step S11), an instruction signal is output from the reduced voltage detection unit 13 to the reset unit 14. The instruction signal is also input to the storage unit 3, and in response thereto, the voltage drop information is stored in the storage unit 3 (step S13).

  On the other hand, when the microcomputer 2 is in a runaway state (Yes in step S12), an instruction signal is output from the reduced voltage detection unit 13 to the reset unit 14.

  The reset unit 14 sets the reset signal to “L” when an instruction signal is input from either the voltage drop detection unit 13 or the runaway detection unit 15. The microcomputer 2 is reset in response to the reset signal becoming "L" (step S14). When the voltage drop information is stored in the storage unit 3, the storage of the voltage drop information in the storage unit 3 is held even during resetting of the microcomputer 2.

  Thereafter, the microcomputer 2 restarts. The restarted microcomputer 2 checks whether or not the voltage drop information is stored in the storage unit 3 (step S15). If voltage drop information is not stored in storage unit 3 (No in step S15), it is determined that microcomputer 2 has been reset due to a runaway state, and the process is terminated.

  On the other hand, if the voltage drop information is stored in the storage unit 3 (Yes in step S15), it is determined that the microcomputer 2 has been reset due to the voltage VCC being less than the minimum operating voltage Vt. In this case, the battery 51 is deteriorated and its voltage is lower than usual. For this reason, in order to reinforce the charging of the battery 51, the microcomputer 2 instructs the alternator 52 to increase its power generation amount beyond the normal level.

  Specifically, the microcomputer 2 instructs the target voltage of the alternator 52 to be higher than the normal reference voltage (for example, 12V to 13V) (for example, 14V to 15V) by the target voltage changing function. A signal to be transmitted is transmitted to the alternator 52 (step S16). Thereby, the electric power generation amount of the alternator 52 increases from the normal time, and the charging of the battery 51 is strengthened. As a result, the voltage of the battery 51 can be increased.

  FIG. 3 is a time chart showing changes in various signals when the voltage of the battery 51 decreases at the start of the engine. At the start of this chart, the ignition switch 92 is turned off and the engine 57 is not started.

  First, at time T1, the ignition switch 92 is turned on by a user operation. Thereby, electric power is supplied from the battery 51 to the idling stop device 1, and the microcomputer 2 is activated.

  Next, at time T2, the start switch 93 is turned on by the user's operation and the starter motor 55 is driven. As the starter motor 55 is driven, the voltage BATT of the battery 51 decreases. As a result, the voltage of the power supply line 91 decreases. Further, when the battery 51 is deteriorated, the voltage VCC of the power source of the microcomputer 2 is also lowered.

  In this way, when the voltage VCC of the power source of the microcomputer 2 decreases and becomes lower than the minimum operating voltage Vt of the microcomputer 2 at time T3, the reduced voltage detection unit 13 detects this and generates an instruction signal. (Referred to as “H”). In response to this, the reset unit 14 sets the reset signal to “L”, and the microcomputer 2 stops its operation for resetting. At the same time, an instruction signal from the reduced voltage detection unit 13 is also input to the storage unit 3, and the voltage drop information is stored in the storage unit 3.

  Thereafter, when the load on the starter motor 55 decreases as the engine 57 rotates, the voltage BATT of the battery 51 gradually increases. For this reason, the voltage of the power supply line 91 and the voltage VCC of the power supply of the microcomputer 2 also rise. When the voltage VCC of the power source of the microcomputer 2 rises and becomes equal to or higher than the minimum operating voltage Vt of the microcomputer 2 at time T4, the reduced voltage detection unit 13 stops the instruction signal (set to “L”). In response to this, the reset unit 14 sets the reset signal to “H” and the microcomputer 2 is restarted.

  The restarted microcomputer 2 confirms that the voltage drop information is stored in the storage unit 3, and instructs the alternator 52 to set the target voltage higher than the normal reference voltage by the target voltage changing function. . Thereby, after the time point T4, the power generation amount of the alternator 52 increases more than usual, and the charging of the battery 51 is strengthened.

  At time T5, when the ignition switch 52 is turned off by a user operation, the voltage VCC of the power source of the microcomputer 2 becomes 0, and the microcomputer 2 stops its operation. Further, the voltage drop information is erased from the storage unit 3.

  As described above, in the idling stop device 1 of the present embodiment, when the voltage of the battery 51 decreases and the voltage VCC of the power source of the microcomputer 2 becomes less than the minimum operating voltage Vt of the microcomputer 2, The microcomputer 2 is reset. On the other hand, the voltage drop information is stored in the storage unit 3. For this reason, the microcomputer 2 after the reset can grasp that the voltage of the battery 51 has decreased based on the voltage decrease information, and thereafter, the power generation amount of the alternator 52 that charges the battery 51 is increased to enhance the charging of the battery 51. By doing so, the voltage of the battery 51 can be raised.

<2. Second Embodiment>
Next, a second embodiment will be described. The configuration and processing of the idling stop device 1 of the second embodiment are almost the same as those of the first embodiment, but in the second embodiment, the microcomputer 2 has a function of invalidating the idling stop function. It has more.

  In the first embodiment, when the voltage of the battery 51 is lowered, the power generation amount of the alternator 52 is increased more than usual. Since the alternator 52 generates power using the kinetic energy of the engine 57, the charging of the battery 51 can be further strengthened by preventing the engine 57 from being stopped as much as possible. Therefore, in the second embodiment, when the voltage VCC is less than the minimum operating voltage Vt and the voltage drop information is stored in the storage unit 3, the power generation amount of the alternator 52 is increased more than usual and idling is performed. The stop function is disabled.

  FIG. 4 is a diagram showing a processing flow of the idling stop device 1 related to the resetting of the microcomputer 2 in the second embodiment. Steps S21 to S26 in this process are the same as steps S11 to S16 in FIG. For this reason, below, it demonstrates centering around difference with FIG.

  The microcomputer 2 reset and restarted in step S24 confirms whether or not the voltage drop information is stored in the storage unit 3 (step S25). If the voltage drop information is stored in the storage unit 3 (Yes in step S25), it is determined that the microcomputer 2 has been reset due to the voltage VCC being less than the minimum operating voltage Vt. For this reason, in order to strengthen the charging of the battery 51, the microcomputer 2 instructs the alternator 52 to increase the amount of power generation (step S26).

  Subsequently, the microcomputer 2 invalidates the idling stop function (step S27). Therefore, thereafter, even if a predetermined stop condition is satisfied based on a signal indicating the running state, the engine 57 is not automatically stopped. That is, even if the vehicle is in an idling state, the engine 57 is not stopped, so that the battery 51 can be charged with the power generation amount of the alternator 52 increased in the idling state. As a result, the voltage of the battery 51 can be effectively increased.

<3. Modification>
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible. Below, such a modification is demonstrated. All forms including those described in the above embodiment and those described below can be combined as appropriate.

  In the above embodiment, the power generation amount of the alternator 52 is increased from the normal amount by making the target voltage of the alternator 52 higher than the reference voltage. However, the rotational speed (idle rotational speed) of the engine 57 in the idling state is increased. Alternatively, the power generation amount of the alternator 52 may be increased from the normal amount by increasing the normal rotation speed (for example, 600 rpm) (for example, 800 rpm).

  Further, the power supply voltage of the storage unit 3 may be directly supplied from the battery 51, or a nonvolatile memory such as an EEPROM or a flash memory may be adopted as the storage unit 3. In this case, the voltage drop information can be stored in the storage unit 3 regardless of whether the ignition switch is on or off. For this reason, if the microcomputer 2 is reset even once due to the voltage drop of the battery 51, the power generation amount of the alternator 52 is increased from the normal level. The voltage drop information may be deleted from the storage unit 3 when the battery 51 is replaced.

  In the above embodiment, the storage unit 3 is composed of a logic circuit capable of storing 1-bit information. However, a memory having a relatively large storage capacity may be employed. However, if the storage unit 3 includes only one logic circuit capable of storing 1-bit information as in the above embodiment, the storage unit 3 can be realized at a very low cost.

  Further, in the above-described embodiment, it has been described that various functions are realized in software by the arithmetic processing of the CPU according to the program. However, some of these functions are realized by an electrical hardware circuit. Also good. Conversely, some of the functions realized by the hardware circuit may be realized by software.

DESCRIPTION OF SYMBOLS 1 Idling stop apparatus 2 Microcomputer 3 Memory | storage part 11 Regulator 13 Reduced voltage detection part 51 Battery 52 Alternator 55 Starter motor

Claims (3)

An idling stop device mounted on a vehicle for automatically stopping / starting the engine of the vehicle,
A microcomputer having an idling stop function that automatically stops the engine when a predetermined stop condition is satisfied, and automatically starts the engine when a predetermined start condition is satisfied while the engine is stopped;
Detecting means for detecting that the voltage of the power source of the microcomputer obtained by stepping down the voltage of the battery of the vehicle is less than the minimum operating voltage of the microcomputer;
Storage means for storing voltage drop information regardless of the state of the microcomputer when the voltage of the power supply becomes less than the minimum operating voltage;
When the voltage drop information is stored in the storage means, instruction means for instructing to increase the power generation amount of the generator for charging the battery;
An idling stop device comprising: The idling stop device according to claim 1,
The microcomputer invalidates the idling stop function when the voltage drop information is stored in the storage means. Equipped with a microcomputer having an idling stop function for automatically stopping the engine of the vehicle when a predetermined stop condition is satisfied, and automatically starting the engine when the predetermined start condition is satisfied while the engine is stopped A method for charging a battery in a vehicle,
Detecting that the voltage of the power source of the microcomputer obtained by stepping down the voltage of the battery of the vehicle is less than the minimum operating voltage of the microcomputer;
Storing the voltage drop information in the storage means regardless of the state of the microcomputer when the voltage of the power supply becomes less than the minimum operating voltage;
When the voltage drop information is stored in the storage means, instructing to increase the power generation amount of the generator for charging the battery;
A battery charging method comprising: