JP4641838B2 - Idle operation stop control method for internal combustion engine - Google Patents

Description

  The present invention relates to an idle operation stop control method for an internal combustion engine that stops idle operation under a predetermined condition when the internal combustion engine enters an idle operation state when a vehicle is stopped.

  2. Description of the Related Art Conventionally, when an internal combustion engine, that is, an engine is in an idle operation state when a vehicle is stopped by an intersection signal or the like, an engine is stopped for the purpose of improving fuel consumption and reducing the amount of exhaust gas. Such a stop of the idling operation is configured to be executed when the state of charge of the battery satisfies a predetermined condition on the basic condition that the vehicle is stopped or the brake is operated. Has been.

For example, in the device described in Patent Document 1, the power necessary for restarting the engine stopped in the idle operation state based on the battery charge state estimated in consideration of the ambient temperature and the deterioration state of the battery. Is output possible, and the engine stoppage is determined based on the estimation result. In this case, the determination is made when the output voltage of the battery is equal to or higher than the reference voltage necessary for driving the motor generator for starting the engine.
JP 2001-304008 A

  By the way, the torque required for starting the engine changes depending on its temperature. That is, the torque in the former is small in the case of a temperature at which heating with cooling water is possible and in the case of a temperature when traveling uphill. Therefore, the electric power required to drive the motor generator or starter for starting the engine differs between the two.

  However, in the device described in Patent Document 1, it is determined that the engine is stopped when it is equal to or higher than the reference voltage required for driving the motor generator. Therefore, when the output voltage of the battery is lower than the reference voltage, the operation is stopped. Cannot be determined. In other words, when the engine temperature is low and the torque required to start the engine is small, it is possible to start even if the output voltage of the battery is lower than the reference voltage. Idle operation will continue. For this reason, by improving the fuel consumption during this period, it is impeded to improve the fuel efficiency.

  The object of the present invention is to eliminate such problems.

That is, the method for controlling the idling operation of an internal combustion engine according to the present invention provides a start torque of the internal combustion engine as the temperature of the internal combustion engine increases in a vehicle including a battery that can store electric power required to start the internal combustion engine by an electric motor. An idle operation stop control method for an internal combustion engine that stops idle operation of the internal combustion engine if the state of charge of the battery is within a predetermined condition within a temperature range of the internal combustion engine in which the based on the battery current and voltage up to the point determined by calculating the possible output power, and estimates the resistance force against the start of the internal combustion engine when stopping the internal combustion engine at the time determines the state of charge of the battery The required power required to start the internal combustion engine is calculated based on the resistance force, and the calculated output power exceeds the required power. Battery and permits the stop of the idle operation of the internal combustion engine when it is charged.

  In the present invention, an electric motor refers to a device that converts electric energy into rotational energy, and is a motor (so-called hybrid engine) that outputs a driving force for running a vehicle by selectively functioning in combination with an internal combustion engine. Motor), a starter used only at the time of starting, a generator that generates rotational energy by applying electric power, and the like. The internal combustion engine may be any engine that can be started by the rotational energy of the electric motor, and includes a spark ignition type 2-stroke and 4-stroke engine, a diesel engine, and the like.

In addition, in the present invention, the resistance force against the start of the internal combustion engine refers to a force acting on the internal combustion engine so as to prevent the start when the internal combustion engine is started. This includes frictional resistance (friction), frictional resistance due to automatic transmission fluid when a torque converter is connected to the internal combustion engine, and frictional resistance characteristics of each internal combustion engine. These frictional resistances can actually be estimated from the starting torque of the engine and hence the required torque of the electric motor.

With such a configuration, for starting the internal combustion engine based on the resistance force by estimating a resistance force opposing the starting of the internal combustion engine when stopping the internal combustion engine at the time it determines the state of charge of the battery By calculating the required power, the required power according to the state of the internal combustion engine can be obtained. And since the stop of idle driving | operation is permitted in the charge state of the battery in which the electric power which can be output exceeds required electric power, even if it stops an internal combustion engine, it becomes possible to start reliably.

  In order to easily and accurately calculate the required power, it is preferable that the estimation of the resistance force is based on the temperature of the internal combustion engine. In addition, when the vehicle further includes an automatic transmission having a torque converter, it is preferable to estimate the resistance based on the temperature of the automatic transmission.

  As described above, the present invention can obtain the required power according to the state of the internal combustion engine, and permits the stop of the idle operation in the charged state of the battery in which the power that can be output exceeds the required power. Even if it stops, it can start reliably. Therefore, the idling operation of the internal combustion engine can be stopped in the state of charge of the battery that can start the internal combustion engine, and the fuel consumption reduction effect can be improved.

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

  In FIG. 1, an engine 100 mounted on a vehicle such as an automobile is a water-cooled type and integrally includes an automatic transmission AT having a torque converter. Further, the engine 100 is provided with an alternator AL that is rotationally driven by the engine 100, and a starter ST that is an electric motor that rotates when energized and supplies rotational driving force to the engine 100. In order to operate the engine 100, an electronic control device 1 that controls the fuel injection amount, the engine speed, the intake air amount during idle operation, and the like, and a battery 2 that serves as a power source for the electric system of the vehicle including the electronic control device 1 The engine 100 and the vehicle are equipped with various sensors that are connected to the electronic control unit 1 and detect the operating state of the engine 100. Various sensors that are well-known in this field can be widely used as various sensors necessary for controlling the operation of engine 100. Therefore, a specific description is omitted and the configuration that characterizes the present invention is provided. Only those related to will be described below.

  Specifically, a coolant temperature sensor 3 that detects a coolant temperature as a temperature of the engine 100 and outputs a coolant temperature signal a, a vehicle speed sensor 4 that detects a vehicle speed and outputs a vehicle speed signal b, and a charging current described later. A battery temperature sensor 5 that detects the temperature of the battery 2 attached to the sensor 7 and outputs a battery temperature signal c, detects the temperature of the automatic transmission fluid (hereinafter referred to as ATF) of the automatic transmission AT, that is, the ATF temperature, and detects oil. An oil temperature sensor 6 for outputting a temperature signal d, a charging current sensor 7 for outputting a charging voltage e corresponding to the charging current attached to a wiring connected to the battery 2 from the alternator AL, and an ignition switch 8 from the battery 2 A discharge current sensor 9 that outputs a discharge voltage f corresponding to the discharge current attached to the wiring, An idle switch 10 that detects an open / closed state (not shown) and outputs an IDL signal g, a brake switch 11 that detects an operating state of a brake pedal (not shown) and outputs a brake signal h, and a shift of the automatic transmission AT Position switches 12 that detect the position and output a position signal k are respectively disposed at corresponding portions of the engine 100 or the vehicle.

  The electronic control device 1 is mainly configured by a microcomputer system including a central processing unit 1a, a storage device 1b, an input interface 1c, and an output interface 1d. The storage device 1b stores an idle operation stop control program, which will be described later, and temporarily stores calculation results generated by executing the program and stores data necessary for idle operation control. The input interface 1c receives signals output from the above-described sensors and switches, a charging voltage, a discharging voltage, and a DC voltage between the terminals of the battery 2. Thus, the electronic control device 1 functions as a charge ammeter, a discharge ammeter, and a DC voltmeter. Further, from the output interface 1d, a drive signal m corresponding to the calculated fuel injection time (fuel injection amount) for a fuel injection valve (not shown) and an ISC for controlling the intake air amount during idling operation. A control signal n is output to a valve (not shown), and an ignition signal p is output to a spark plug (not shown).

  Although not shown, the electronic control unit 1 includes an A / D converter for converting an input analog signal into digital data. The A / D converter includes a water temperature signal a, an oil temperature signal d, and the like. Are converted into digital data at regular intervals and output to the central processing unit 1a. Further, illustration of the power supply line for the electronic control device 1 is omitted.

The electronic control device 1 executes an idle operation stop control program, and permits the engine 100 to stop idling if the state of charge of the battery 2 is under a predetermined condition when the vehicle stops . Specifically, for example, the vehicle speed is below a predetermined speed based on the vehicle speed signal b output from the vehicle speed sensor 4, the brake pedal is operated based on the brake signal h output from the brake switch 11, the position switch In addition to this basic condition, the fact that the automatic transmission AT is set to the drive range based on the position signal k output by the engine 12 is determined in addition to the basic condition. Under the condition that electric power exceeding the electric power required for starting calculated according to the state is stored in the battery 2, the stop of idle operation is determined when these conditions are satisfied.

  It should be noted that in determining to stop the idle operation, the basic condition described above is satisfied (satisfied) and the state of charge in the battery 2 satisfies a predetermined condition. The order of determining whether or not each condition is satisfied is not particularly limited. That is, the determination based on the charge state of the battery 2 is performed when the basic condition is satisfied, and conversely, the basic condition is satisfied when the charge state of the battery 2 satisfies a predetermined condition. It may be any of those that determine that there is. Furthermore, the determination by the battery 2 may be performed when one of the basic conditions is satisfied.

  When one of the conditions is satisfied, the stop of the idle operation is permitted. That is, when the condition that the electric power exceeding the electric power required for starting calculated according to the state of the engine 100 is stored in the battery 2 is satisfied, the idle operation can be stopped. This indicates that it is possible to stop the idle operation on the premise of establishment.

  The configuration of the idle operation stop control program will be described with reference to FIG.

  This idle operation stop control program is repeatedly executed at a predetermined cycle while the engine 100 is rotating. Then, the procedure described below is executed in a state where the above-described basic conditions are satisfied.

  In addition, in this idle operation stop control program, in order to calculate the necessary power required for starting the engine 100, the coolant temperature and the friction that becomes a resistance force when starting the engine 100 at the time of executing this program, that is, the time when this program is executed. A map that associates the starting torque required for starting the corresponding engine 100, that is, the required torque of the starter ST, and a map that associates the required power required for starting based on the required torque with the coolant temperature are attached. In these maps, representative values of each parameter (cooling water temperature, starting torque, required torque) are set based on actual measured values, and the starting torque, and hence the required torque, may vary during production of each engine. It is set with a value that takes into account the width.

  Similarly, a correction coefficient for correcting the required torque obtained from the coolant temperature is set from the relationship between the ATF temperature and the required torque required for starting the engine 100. That is, in the automatic transmission AT having a torque converter, the viscosity of the ATF becomes a resistance force or friction with respect to the engine 100. The friction due to the ATF is estimated based on the ATF temperature, and the correction coefficient is calculated by the estimated friction. Is set. Similar to the friction of the engine 100 itself, the friction due to the ATF also tends to increase as the temperature increases, and the required torque for the friction also increases. Therefore, the correction coefficient based on the ATF temperature is set so as to increase as the temperature increases.

  As shown in FIG. 3, the required torque of the starter ST shows a high value when the cooling water temperature is low, then decreases as the temperature rises, and then rises again to increase the cooling water temperature. High value. Therefore, the required power required for starting engine 100 increases as the cooling water temperature increases immediately before the completion of the warm-up operation, when associated with the cooling water temperature. In this case, the range of the cooling water temperature at which the idling operation is stopped is actually made during traveling, so it is set within the temperature range before the overheating from the cooling water temperature after complete warm-up. It is. In this temperature range, the required torque increases linearly with respect to the cooling water temperature. By setting such a temperature range, when the coolant temperature in winter is low, the engine 100 is not stopped even when the vehicle is stopped in the idle operation state, so that the heating of the vehicle interior can be continued.

  First, in step S1, the coolant temperature and the ATF temperature are read based on the water temperature signal b from the coolant temperature sensor 4 and the oil temperature signal d from the oil temperature sensor 6. The coolant temperature is also used to set the fuel injection amount, for example, and is detected before the idle operation stop control program is executed. In step S1, the coolant temperature is detected as such. The latest coolant temperature and ATF temperature stored in the storage device 1b are read from the storage device 1b and read as data of this program.

  In step S2, a map is searched based on the read cooling water temperature, and if necessary, an interpolation calculation is performed to determine the engine 100 starting torque with respect to the cooling water temperature, and thus the required torque of the starter ST, based on the ATF temperature. The required torque for calculating the required power is corrected by correcting the required torque obtained using the correction coefficient.

  In step S <b> 3, the required power necessary for starting engine 100 is calculated based on the estimated required torque. When this required power is supplied to the starter ST, the starter ST generates the required torque by the starter ST. This required power corresponds to the required torque and changes with the same tendency as the required torque shown in FIG. 3, that is, with a tendency to increase linearly with respect to the cooling water temperature.

  In step S4, the integrated values of the charging current and discharging current of the battery 2 at the current time are read. The charging current and the discharging current are detected every predetermined time until the idle operation stop control program is executed. Then, the detected charging current and discharging current are integrated, and the integrated value is stored in the storage device 1b.

  In step S5, the temperature of the battery 2 is detected based on the battery temperature signal c from the battery temperature sensor 5. When the temperature of the battery 2 increases, the internal resistance value of the battery 2 decreases, and the discharge current increases in the same charging state as compared with the case where the battery temperature is low. That is, the discharge current of the battery 2 varies depending on the battery temperature. Therefore, when calculating the power that can be output from the battery 2, the battery temperature is used to correct the power that can be output based on the variation of the discharge current due to the battery temperature.

  In step S6, it is determined whether or not the lowest voltage between the terminals of the battery 2 when the engine 100 was last started is equal to or higher than a certain voltage. That is, when the engine 100 is started when the current engine 100 is operated, the DC voltage between the terminals of the battery 2 is measured, and the measured DC voltage is stored in the storage device 1b as the lowest voltage of the battery 2. It is something to keep.

  In step S7, the state of charge of the battery 2 is estimated. This estimation is performed based on the charging current and discharging current integrated value read in step S4, the battery temperature detected in step S5, and the lowest voltage of the battery 2 determined in step S6. Based on the difference between the charge current integrated value and the discharge current integrated value, and the minimum voltage equal to or higher than a certain voltage, the power that can be output by the battery 2 is calculated, and the obtained power is corrected by the battery temperature detected in step S5. Then, the power that can be substantially output at the present time is calculated, and the state of charge of the battery 2 is estimated.

  In step S8, it is determined whether or not the battery 2 can output power necessary for starting. This determination determines that the output is possible when the state of charge of the battery 2 estimated in step S7, that is, the power that can be output exceeds the required power obtained by calculation in step S3.

  In step S9, assuming that the state of the battery 2 satisfies the battery condition for stopping the idle operation, the engine stop (idle operation stop) is permitted assuming that the engine 100 during the idle operation may be stopped. On the other hand, in step S10, the idle operation stop is not permitted because the battery condition is not satisfied.

  A case where the vehicle is stopped by a signal at an intersection in such a configuration will be described. In this case, in the automatic transmission AT, the shift position remains in the drive range so that the vehicle can start after the signal is switched. As described above, when the vehicle stops, the engine 100 becomes idle.

  In the above operation state, steps S1 to S6 are executed, and information necessary for determining the state of charge of the battery 2 is collected. If the lowest voltage of the battery 2 at the time of the previous start of the engine 100 is below a certain voltage, the determination in step S6 is performed, and then the engine 100 whose charge state of the battery 2 is idling is stopped. Assuming that the condition is not satisfied, stop of idle operation is not permitted (step S10). That is, when the minimum voltage of the battery 2 at the time of the previous start is lower than a certain voltage in this way, if the idle operation is stopped, the battery 2 is in a state where it cannot supply the power required for the start to the starter ST. Even if other idle operation stop conditions (basic conditions) are satisfied, the idle operation is not stopped.

  On the other hand, if Step S1 to Step S6 are executed and the lowest voltage of the battery 2 at the previous start of the engine 100 is equal to or higher than a certain voltage, Step S7 is executed to change the state of charge of the battery 2 presume. When it is determined in step S8 that the battery 2 is capable of outputting the power required for starting in the estimated state of charge of the battery 2, the stop of the idle operation is permitted. Accordingly, the idle operation is stopped when another idle operation stop condition is satisfied.

  In this case, the electric power that can be output from the battery corresponds to the friction at the start of the engine, which differs depending on the coolant temperature of the engine 100, the required torque of the starter ST required for starting the engine 100, and the starter ST corresponding to the required torque Therefore, it is possible to set the power to the minimum power in the state of the engine 100 at that time. In this case, in this embodiment, the necessary torque is estimated based on the coolant temperature that directly reflects the temperature of the engine 100, and the starter ST is necessary to generate the necessary torque from the necessary torque. Since the required power is calculated, the required torque can be accurately estimated.

  As a result, even when the state of charge of the battery 2 is not perfect, if the battery 2 is charged with electric power that can provide the necessary torque of the starter ST necessary for starting the engine 100, the idle operation of the engine 100 can be performed. Can be stopped, and the engine 100 can be stopped when an idle operation stop condition other than the battery 2 is satisfied. Therefore, even when the power of the battery 2 is consumed by various electric loads including a car stereo and the state of charge is lowered, the engine can be used if the predetermined battery condition is satisfied in step S6 and step S8. Since the engine 100 during idle operation is stopped while the battery 2 at the start limit of 100 is charged, the number of idle operation stops can be increased, and thus fuel consumption can be improved by reducing fuel consumption.

  The present invention is not limited to the above embodiment.

  In the above embodiment, the description has been given of the case where the stop of the idle operation of the engine 100 is permitted based on the state of charge of the battery 2 when the vehicle is stopped, but only the internal combustion engine is used as a power source for traveling. When the vehicle 2 is traveling at a reduced speed on the premise of stopping and immediately before stopping when the traveling speed is equal to or lower than the predetermined speed, the idle operation of the engine 100 is performed when the state of charge of the battery 2 satisfies the predetermined condition described above. It is good also as a structure which permits the stop of this. Further, in the case of a vehicle equipped with a hybrid engine in which an electric motor and an internal combustion engine are combined, the decelerating traveling (regenerative traveling by the electric motor) that no longer requires the driving force of the internal combustion engine constituting the hybrid engine for traveling. The time may be used as a precondition for stop permission control for idle operation depending on the state of charge of the battery 2 in addition to when the vehicle stops.

  Also, for example, every time the engine is started, as shown in the above embodiment, the engine temperature, the automatic transmission ATF temperature, the charging current, the discharging current, the voltage between the terminals, and the battery temperature are measured. From the measured value, the power consumed at the start corresponding to at least the friction that changes depending on the engine temperature, in other words, the power required at the start corresponding to the temperature of each engine is calculated. Then, by storing and storing each calculated power, the required power at the start corresponding to the characteristic (variation) unique to each engine is learned. That is, in the above embodiment, the map for estimating the starting torque is not set for each engine mounted on the vehicle, but is created based on the actual measurement value of the engine of the same type. It is difficult to reflect the characteristics, but by learning the required power in this way, the unique characteristics of each engine can be effectively reflected in the required power, so the engine idling can be stopped accurately. Can be executed.

  In addition, in the case of controlling the starting from the idling stop based on the crank angle at the time of the engine stop, the starting torque may be estimated in consideration of the crank angle.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

The block diagram of embodiment of this invention. The flowchart which shows the general | schematic control procedure of the embodiment. The graph which shows the content of the map of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electronic controller 1a ... Central processing unit 1b ... Memory | storage device 1c ... Input interface 1d ... Output interface 2 ... Battery 100 ... Engine

Claims (3)

In a vehicle comprising a battery capable of storing electric power required to start an internal combustion engine by an electric motor, the battery is within a temperature range of the internal combustion engine in which the starting torque of the internal combustion engine increases as the temperature of the internal combustion engine increases. An idle operation stop control method for an internal combustion engine that stops the idle operation of the internal combustion engine if the state of charge of the engine is under a predetermined condition,
Calculate the power that can be output based on the current and voltage of the battery up to the time when the battery charge state is determined,
Estimates the resistance force against the start of the internal combustion engine calculates the required electric power required to start the internal combustion engine based on the resistance force when stopping the internal combustion engine at the time determines the state of charge of the battery,
An idle operation stop control method for an internal combustion engine that permits stop of the idle operation of the internal combustion engine when the battery is charged in a state where the calculated output power exceeds the required power.   2. The method of controlling idle stop of an internal combustion engine according to claim 1, wherein the estimation of the resistance force is based on the temperature of the internal combustion engine. The internal combustion engine idle operation stop control method according to claim 1, wherein the vehicle further includes an automatic transmission having a torque converter, and the resistance force is estimated based on a temperature of the automatic transmission.

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