JP5063380B2 - Control method for internal combustion engine - Google Patents

Description

  The present invention relates to a method for controlling an internal combustion engine in a vehicle that stops the internal combustion engine when the vehicle stops.

  Conventionally, in an internal combustion engine, that is, a vehicle equipped with an engine, it is known to control the operation of the internal combustion engine so that the internal combustion engine is automatically stopped when the vehicle stops due to a signal or the like during traveling (for example, Patent Document 1). That is, when the vehicle is stopped, the engine operation is stopped in order to save fuel, reduce exhaust gas, or reduce noise.

In the one described in Patent Document 1, when the vehicle is stopped, the oil pump driven by the engine stops, so that the oil in the automatic transmission is released from the oil passage, and the oil pressure is automatically reduced when the engine is restarted. The fact that the forward clutch or low clutch in the transmission cannot be quickly connected is the oil pressure necessary for connecting the low clutch regardless of the throttle opening at the time of restart, in other words, the pressure when the low clutch is connected, Until the low clutch pressure reaches a predetermined value, a torque down command is output to the engine control unit. By adopting such a configuration, at the time of restart, when the automatic transmission is in the neutral state, the accelerator pedal is depressed, and the engine is rapidly engaged with the forward clutch in the process of rapidly increasing the engine speed. This prevents a shock, that is, an unstable state in which the engine speed repeatedly increases and decreases in a short time.
JP 2003-294122 A

  However, with such a configuration, since the torque down command is always output to the engine control unit until the low clutch pressure reaches a predetermined value, the increase in rotation at the time of restart is delayed. Thus, drivability such as acceleration is reduced if the engine does not rotate during restart. For this reason, the torque down control at the time of restart has to be kept to the minimum necessary.

  Therefore, the present invention aims to eliminate such problems.

That is, an internal combustion engine provided with a throttle valve, an automatic transmission provided with a clutch, and a mechanical oil pump driven by the internal combustion engine to circulate hydraulic oil of the automatic transmission with a predetermined hydraulic pressure. Based on at least one of the throttle valve opening and the engine speed when restarting the internal combustion engine from a state where the internal combustion engine is stopped with the automatic transmission set to the drive range in a vehicle that stops idling operation The internal combustion engine is operated by reducing the torque by a torque reduction amount that is set smaller as the throttle valve opening is smaller or the engine speed is lower , and the internal combustion engine is restarted from the above state. If the throttle valve opening at that time is less than the predetermined value, it is prohibited to reduce the torque of the internal combustion engine It is characterized in.

  According to such a configuration, when the internal combustion engine is started from a state in which the automatic transmission is set to the drive range and the internal combustion engine is stopped, and the internal combustion engine is operated by reducing the torque at the start, the torque is reduced. Since the amount is set based on at least one of the opening degree of the throttle valve and the engine rotation, it is possible to reduce the torque in an optimum state corresponding to the operating state of the internal combustion engine in this case. In this case, the lower the throttle opening and the lower the engine speed, the smaller the amount of torque reduction, so that it is possible to suppress the torque from being reduced more than necessary. Therefore, it is possible to accurately suppress the clutch engagement shock and improve the starting acceleration according to the opening of the throttle valve.

Prohibiting a decrease in the torque of the internal combustion engine when the opening of the throttle valve is less than or equal to a predetermined value is preferable in order to further improve the acceleration performance at the time of starting .

  In order to execute control for quickly reducing the torque, it is preferable to reduce the torque by retarding the ignition timing.

  The present invention is configured as described above, and starts the internal combustion engine from a state where the internal combustion engine is stopped in a state where the automatic transmission is set to the drive range, and operates the internal combustion engine by reducing the torque at the start. In this case, the amount of torque decrease is based on at least one of the throttle valve opening and the engine speed. The lower the throttle opening and the lower the engine speed, the smaller the torque decrease. Can be suppressed, and the torque can be reduced in an optimum state corresponding to the operating state of the internal combustion engine at that time. Therefore, it is possible to accurately suppress the engagement shock of the clutch and improve the acceleration performance at the start according to the opening of the throttle valve.

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

  In the embodiment described below, as shown in FIG. 1, an internal combustion engine, for example, a three-cylinder spark ignition engine (hereinafter abbreviated as an engine) 1 is integrally provided with an automatic transmission 2, and particularly a vehicle, Is mounted on passenger cars.

The engine 1 may have a structure well known in this field, and is provided downstream of an intake system surge tank 3 and opens and closes in response to the operation of an accelerator pedal (not shown), and its open / closed state. A throttle opening sensor 5 for detecting the engine speed, a brake sensor 6 for detecting the operation of a brake pedal (not shown), an engine speed sensor 7 for detecting engine speed (hereinafter referred to as engine speed), and an engine. 1, a temperature sensor 8 that detects the coolant temperature, a cam position sensor 9 that detects the rotation state of the engine 1 and outputs a cylinder discrimination signal and a crank angle reference position signal, and an air-fuel ratio for controlling the fuel injection amount. An O ₂ sensor 10 and the like are basically provided. Each cylinder 11 is provided with a spark plug 12.

  The automatic transmission 2 includes a torque converter 2a, a transmission gear device 2b including a clutch and a brake, and a mechanical oil pump (hereinafter referred to as an oil pump) that circulates hydraulic oil at a predetermined hydraulic pressure with respect to a necessary portion of the transmission gear device 2b. 2c), and the gear meshing configuration in the drive range is changed by a combination of a clutch and a brake. The oil pump 2c is driven by the engine 1, and does not supply or circulate hydraulic oil to the transmission gear device 2b when the engine is stopped.

  Each sensor provided in the engine 1 is electrically connected to the electronic control unit 13. The electronic control unit 13 is mainly composed of a microcomputer system, and controls the operation of the engine 1 by executing a built-in program. The configuration of the microcomputer system itself may be known in the art. The electronic control unit 13 controls the operation of the engine 1 and, when the vehicle is temporarily stopped during traveling and the idling stop condition is satisfied, stops the idling operation during the stop period. Control for starting the engine 1 is performed. The idling operation is stopped, for example, when the idling stop condition of the engine 1 is satisfied when the vehicle is stopped, and the fuel injection is stopped and the engine 1 is stopped. Therefore, the electronic control unit 13 determines that the case where the traveling speed of the vehicle is 0 km / h, for example, in the state where the output signal of the brake sensor 6 is received as the idling stop condition, and performs the idling operation. The engine 1 is controlled to stop. The idling stop condition itself may be one that is well known in the art.

  The electronic control unit 13 is programmed to start the engine 1 when the output signal of the brake sensor 6 disappears when the idling operation is stopped. Specifically, when the engine 1 is started from a state where the engine 1 is stopped in a state where the automatic transmission 2 is set to the drive range, the electronic control unit 13 determines the opening degree of the throttle valve 4 and the engine speed. Based on at least one of them, the engine 1 is programmed so as to decrease the torque by the amount of decrease in torque that is set to be smaller as the opening of the throttle valve 4 is smaller or the engine speed is lower. The engine start control program from idling stop will be described below.

  In this program, the amount of torque reduction is set by the throttle opening and the engine speed. Specifically, the retard amount of the ignition timing is set by a two-dimensional map based on the throttle opening and the engine speed. In the two-dimensional map, the retard amount of the ignition timing is set smaller as the throttle opening is smaller and the engine speed is smaller. In other words, the retardation amount corresponding to the low load low rotation operation region is set to be small, and the retardation amount corresponding to the high load high rotation operation region is set to be large. Note that the retard amount corresponding to the operation region where the throttle opening or the engine speed is smaller than a predetermined value is 0 degree (crank angle), and in such a case, a decrease in torque is substantially prohibited. It is configured to be controlled.

  First, in step S1, it is determined by a start determination flag whether or not the idling operation has been automatically stopped to a state in which start is requested. The start determination flag is set (= 1) when the brake pedal is operated, that is, when the brake sensor 6 outputs an output signal indicating the operation of the brake pedal. When the brake pedal is not depressed, it is reset (= 0). Therefore, when the vehicle is stopped from the running state and the idling operation of the engine 1 is stopped while the vehicle is stopped, and then the operation of the brake pedal is released, the start determination flag is reset to start the engine 1. Is done.

  Next, in step S2, the engine speed and throttle opening of the started engine 1 are detected. Thereafter, in step S3, the above-described two-dimensional map is searched based on the detected engine speed and throttle opening, and the ignition timing retard amount corresponding to the operating state at that time is determined. Then, the operation of the engine 1 is controlled so as to reduce the torque by retarding the ignition timing by the determined retard amount.

  In such a configuration, when the vehicle is running with the automatic transmission 2 in the drive range, for example, when the vehicle stops due to a traffic signal at an intersection, the electronic control unit 13 performs idling operation when the idling stop condition is satisfied. The engine 1 that is performing is stopped, and a start determination flag is set. In this case, the automatic transmission 2 is set in the drive range, but when the engine 1 stops, the oil pump 2c stops, and as a result, a predetermined hydraulic pressure required for the operation of the clutch in the automatic transmission 2 is reached. The following conditions, that is, hydraulic oil pressure is lost. Therefore, the clutch in the automatic transmission 2 is in a disconnected state, and the automatic transmission 2 is substantially in the same state as neutral even though it is set in the drive range.

  Thereafter, when the operation of the brake pedal is released and the accelerator pedal is operated (depressed), the electronic control unit 13 starts the engine 1. When the engine 1 is started, control is performed by executing steps S1 to S3 to retard the ignition timing and reduce the torque based on the throttle opening and the engine speed that change according to the amount of operation of the accelerator pedal. To implement. In this case, if the throttle opening is small without the accelerator pedal being largely operated in a short time, the throttle opening or the engine speed is set to 0 degrees in the two-dimensional map, so the torque is reduced. No control is performed, that is, a reduction in torque is prohibited. When the throttle opening is small or when the engine speed is low, the engine 1 is started and the oil pump is driven to increase the hydraulic pressure of the hydraulic oil to a predetermined pressure or higher. Even when the clutch is engaged, there is no fluctuation at the time of engagement, so torque reduction control is not necessary. Therefore, it is possible to improve the acceleration performance at the start in the operation region where it is not necessary to reduce the torque.

  On the other hand, when the amount of operation of the accelerator pedal is large, the throttle opening is increased, and the engine speed is increased accordingly, the ignition timing is delayed according to the throttle opening and the engine speed. The torque of the engine 1 is reduced by determining the angular amount and retarding the ignition timing by the retard amount. As in this embodiment, by controlling the retard amount of the ignition timing to control the decrease in torque, the amount of fuel injection for which execution of the torque decrease control is delayed by one ignition is controlled, or the intake air Control responsiveness can be made higher than that for controlling the amount.

  Therefore, by reducing the torque of the engine 1, torque transmission between the engine 1 and the automatic transmission 2 is smoothly performed even when the clutch of the automatic transmission 2 is connected. Thereby, the impact at the time of clutch connection can be reduced, and the fluctuation | variation of an engine speed can be suppressed. In addition, when starting the engine 1 after idling is stopped, such an impact when the clutch is connected can be reduced, so an electric pump that can maintain the hydraulic oil pressure of the automatic transmission 2 at a predetermined pressure even when the engine 1 is stopped is adopted. The need to do this can be avoided and the manufacturing cost can be reduced.

  In addition, by making the torque amount to be reduced constant according to the throttle opening and the engine speed, it is possible to suppress the torque from being excessively reduced. It is possible to prevent the engine 1 from stopping. Therefore, it is possible to prevent the exhaust gas purification ability from being lowered when a misfire occurs in such a situation. Or, conversely, when a certain amount of torque to be reduced is small, it is possible to reliably prevent the occurrence of an engagement shock that occurs because the torque reduction is not sufficient in the high engine speed operation region.

  It should be noted that the torque reduction control described above may be either one that reduces the torque stepwise or one that continuously reduces the torque. That is, when the torque is decreased step by step, one is set for each of, for example, two or three regions where the retard amount of the ignition timing is set by the throttle opening and the engine speed. Thus, by setting one retard amount for each set region, it is possible to reduce the capacity of the storage device necessary for storing the retard amount and facilitate the reduction control. be able to. In the configuration in which the torque is continuously reduced, the entire operation region is divided into, for example, four regions, nine regions, or sixteen regions that are defined by the throttle opening and the engine speed. In each of these regions, a representative ignition timing retardation amount is set. When setting the retard amount, interpolation calculation is performed from the retard amount, and the retard amount with respect to the detected throttle opening and engine speed is calculated. With such a configuration, even if the divided and set region changes, the retardation amount can be set to a continuous value, and the torque reduction can be finely controlled.

  Next, another embodiment will be described.

  In this other embodiment, the torque generated in the engine 1 (hereinafter abbreviated as “engine generated torque”) and the torque required in the automatic transmission 2 (hereinafter abbreviated as “AT required torque”) are estimated. A retard amount of the ignition timing is set according to the difference. The control procedure will be described below with reference to the flowchart shown in FIG.

  First, in step S101, it is determined whether or not the start determination flag is reset. If the start determination flag is reset, that is, if the operation of the brake pedal is released, the engine 1 is started. In step S102, the engine speed and the throttle opening are detected.

  In step S103, the engine generated torque and the AT required torque are calculated based on the engine speed and the throttle opening detected in step S102. The engine generated torque is calculated so as to increase as the throttle opening increases and as the engine speed increases. On the other hand, the AT required torque is a torque necessary for setting the drive range from a substantially neutral state in the automatic transmission 2, and is calculated so as to be substantially constant based on the engine speed and the throttle opening. Is done.

  In step S104, the target torque is calculated by subtracting the engine generated torque from the AT required torque obtained in step S103. In step S105, the retard amount of the ignition timing is determined based on the target torque obtained by the calculation. The retard amount of the ignition timing is set with respect to the set torque amount by a one-dimensional map. The retardation amount is set to increase as the torque amount increases. In this map, when the set torque amount is small, that is, when the throttle valve opening or the engine speed is lower than a predetermined value and the engine generated torque is small, the torque of the engine 1 is reduced. In order to prohibit this, the set torque amount, that is, the target torque is set to a value that does not retard.

  As described above, the difference between at least the engine generated torque that changes in accordance with the throttle opening and the AT required torque that is necessary to bring the automatic transmission 2 that is substantially neutral into the drive range, that is, the automatic transmission 2 is neutral. The estimated value of the torque required to increase the oil pressure to the vicinity of the oil pressure required to change from the drive range to the drive range is set as the target torque when the torque of the engine 2 is reduced, and ignition is performed according to the magnitude of the target torque. Since the amount of time delay is set, the torque can be accurately reduced.

  Even in such a configuration, the torque may be controlled stepwise or continuously as described above.

  The present invention is not limited to the embodiment described above.

  The retard amount of the ignition timing may be set by any one of the throttle opening and the engine speed. That is, in the above-described embodiment, the retardation amount is set by a two-dimensional map that is set by the throttle opening and the engine speed, but instead of such a two-dimensional map, it corresponds to the throttle opening. Either one using a map for setting a retard amount or one using a map for setting a retard amount corresponding to the engine speed may be selected and used. Also in such an example, the retard amount is set smaller as the throttle opening is smaller, and the retard amount is set smaller as the engine speed is lower. Since the control procedure is the same as that in the above-described embodiment, the description is omitted.

  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.

BRIEF DESCRIPTION OF THE DRAWINGS The whole structure explanatory drawing of embodiment of this invention. The flowchart which shows the control procedure of the embodiment roughly. The flowchart which shows schematically the control procedure in other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Automatic transmission 2c ... Oil pump 4 ... Throttle bubble 13 ... Electronic control unit

Claims (1)

An internal combustion engine having a throttle valve, an automatic transmission having a clutch, and a mechanical oil pump that is driven by the internal combustion engine and circulates hydraulic oil of the automatic transmission with a predetermined hydraulic pressure, and is idling operation of the internal combustion engine when the vehicle is stopped In vehicles that stop
When the internal combustion engine is restarted from a state where the internal combustion engine is stopped with the automatic transmission set to the drive range, the throttle valve opening is determined based on at least one of the throttle valve opening and the engine speed. The lower the engine speed or the lower the engine speed, the lower the torque, and the lowering of the torque by the amount of torque that is set , and the throttle valve opening when the internal combustion engine restarts from the above state. If it is below the predetermined value, it is prohibited to reduce the torque of the internal combustion engine
A control method of an internal combustion engine characterized by the above .

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