JP2006169989A - Vehicle control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle control device capable of surely improving restarting performance of an engine, by preventing compression self-ignition of fuel injected before stopping the engine. <P>SOLUTION: This vehicle control device has a restarting motor 20 for driving a crankshaft of the engine, and a motor control means 45 for controlling driving of the restarting motor 20 in an automatic stopping period of the engine. The motor control means 45 is controlled so that at least any one cylinder becomes an expansion stroke when stopping the engine, among rows arranged on both ends in the rows of respective cylinders. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle control device configured to automatically stop an engine when a predetermined automatic stop condition is satisfied, and then restart when a predetermined restart condition is satisfied.

In recent years, in order to reduce fuel consumption, reduce CO ₂ emissions, etc., restart conditions have been established such that the engine is automatically stopped temporarily during idling and the vehicle is then started by the driver. At the time, a technology for automatic engine stop control (so-called idle stop control) that automatically restarts the engine has been developed.

In this type of idle stop control, in order to improve the restart performance after the engine is stopped, fuel is injected in advance into the cylinder that is in the expansion stroke when the engine is stopped (hereinafter referred to as the expansion stroke cylinder) before the engine stops. In addition, this fuel is combusted at the time of restart (for example, refer to Patent Document 1).
JP 2001-342876 (particularly [0183] paragraph and [FIG. 23])

  However, in the idle stop control in which fuel is injected in advance to the expansion stroke cylinder before the engine is stopped as in Patent Document 1, the mixture of the injected fuel is compressed and self-ignited in the cylinder during the preceding compression stroke. There was a risk of doing so.

  Therefore, in the idle stop control of the above-mentioned Patent Document 1, there is a possibility that the fuel injected in advance assuming combustion at the time of restart may burn before the engine stops, and the restart performance of the engine is surely improved. Was difficult.

  The present invention has been made in view of the above-described problems, and provides a vehicle control apparatus that can reliably improve engine restart performance by preventing compression self-ignition of fuel injected before the engine is stopped. It is intended to provide.

  In order to solve the above-mentioned problems, the present invention automatically stops the fuel supply in a vehicle having an engine in which a plurality of cylinders are arranged in a row, and stops the fuel supply when a preset automatic engine stop condition is satisfied. When the engine is stopped and fuel is injected into the cylinder that is at least in the expansion stroke when the engine is automatically stopped immediately before the engine is stopped, a restart motor is set when a preset restart condition is satisfied after the engine is automatically stopped. Is a vehicle control device that drives the output shaft of the engine and ignites the air-fuel mixture generated by the fuel injection immediately before the stop and restarts the engine, during the automatic stop period of the engine Motor control means for controlling the driving of the restart motor is provided, and at least one of the cylinders arranged at both ends in the row of each cylinder Cylinders and controls the motor control means so that the expansion stroke at the time of stopping the engine.

  According to the present invention, the cylinder that is in the expansion stroke when the engine is automatically stopped (hereinafter referred to as the expansion stroke cylinder) is the end of the row of each cylinder, so that the fuel injected before the engine is automatically stopped. (Hereinafter referred to as pre-stop-injected fuel) is suppressed from being excessively heated, and the air-fuel mixture generated by this fuel is prevented from undergoing compression self-ignition in the preceding compression stroke in the expansion stroke cylinder. it can.

  That is, when the engine is automatically stopped, heat from combustion during normal operation remains in the engine itself (cylinder, etc.), and heat exchange with this heat causes gas in the fuel chamber, that is, injection before stoppage. Although the air-fuel mixture generated by the fuel is heated, in the present invention, the cylinders arranged at the ends of the cylinder rows, that is, the other cylinders are not adjacent to both sides, and the residual gas is left on one side of the outside air. Since the injection of fuel before stopping is executed for cylinders that can dissipate heat, the amount of heat to the air-fuel mixture due to the heat exchange compared to the cylinders where the other cylinders are adjacent to both sides is reduced. As a result, the air-fuel mixture in the expansion stroke cylinder can be prevented from being heated excessively.

  Therefore, according to the present invention, it is possible to suppress the compression self-ignition of the pre-stop injection fuel before restarting the engine by suppressing excessive heating of the pre-stop injection fuel. The pre-injected fuel can be used effectively, and the restart performance can be improved.

  The cylinders used as the expansion stroke cylinders may be at least one of both ends of each cylinder row. However, the motor control means may be arranged at both ends of each cylinder row every predetermined number of executions of automatic engine stop. It is more preferable to control the motor control means so that the components disposed in are alternately expanded.

  According to this configuration, the cylinder that becomes the expansion stroke cylinder can be changed every predetermined number of executions of the automatic stop of the engine, so that deterioration of the performance of the spark plug over time can be prevented.

  In other words, in the first combustion at the time of engine restart, the combustion conditions are relatively bad, and this combustion causes so-called spark plug fogging, in which foreign matter such as carbon adheres to the spark plug. Although there is a possibility that the ignition performance of the plug will be deteriorated due to adhesion and accumulation, according to the above configuration, the cylinder to be burned first at the time of engine restart can be changed every predetermined number of times of automatic engine stop. As a result of avoiding overlapping of the above-mentioned fog for a specific cylinder, it is possible to prevent deterioration of the ignition performance of the spark plug.

  According to the present invention, the restart performance of the engine can be reliably improved by suppressing the compression self-ignition of the fuel injected before stopping the engine.

  1 and 2 show a schematic configuration of an engine according to an embodiment of the present invention. In these drawings, the engine body 1 is provided with four cylinders 2 in a row (not shown), and a piston 3 is fitted into each cylinder 2 to form a combustion chamber 4 above it. Has been. The piston 3 is connected to the crankshaft 5 via a connecting rod (not shown).

  The combustion chamber 4 of the cylinder 2 is equipped with a spark plug 13 at the top, and an intake port 6 and an exhaust port 7 are opened. A fuel injection valve 8 is provided in the intake port 6. . The fuel injection valve 8 includes a needle valve and a solenoid that are not shown in the figure, and when a pulse signal is input, the fuel injection valve 8 is driven and opened for a time corresponding to the pulse width when the pulse is input. A corresponding amount of fuel is injected into the intake port 6.

  The intake port 6 and the exhaust port 7 are equipped with an intake valve 6a and an exhaust valve 7a, respectively. The intake valve 6a and the exhaust valve 7a are driven by a valve operating mechanism having a camshaft or the like. The opening / closing timings of the intake valve 6a and the exhaust valve 7a of each cylinder 2 are set so that each cylinder 2 performs a combustion cycle with a predetermined phase difference.

  An intake passage 9 and an exhaust passage 10 are connected to the intake port 6 and the exhaust port 7. A throttle valve 12 made up of a rotary valve is disposed in the intake passage 9. The throttle valve 12 is driven by an actuator 12a. In addition, a crank angle sensor 14 that detects the rotation angle of the crankshaft 5 of the engine body 1 is provided.

  As shown in FIG. 2, the crankshaft 5 is provided with a transmission 16 for shifting the rotation of the engine body 1 and transmitting it to the wheels 15 at one end thereof, and restarting the engine at the other end. A device is provided. The restart device includes a restart motor 20 that is rotationally driven by electric power supplied from a battery 18 mounted on a vehicle via an inverter 19, and a chain that transmits the driving force of the restart motor 20 to the crankshaft 5. Or it has the power transmission mechanism 21 which has a belt. The restart motor 20 is in an operating state in which the crankshaft 5 is driven by power supplied from the battery 18 by a built-in clutch (not shown), in a neutral state in which driving connection to the crankshaft 5 is released, or in the crank The battery 18 can be switched to any one of the charged states in which power is generated by the reverse operation from the shaft 5 and the battery 18 is charged.

  In the restart device, the restart motor 20 enters the operating state in response to a control signal output from an ECU (engine control unit: see FIG. 3) 30 described later when the engine is restarted. Is driven in a neutral state, the load on the crankshaft 5 is released, the power generation state is reached, power is generated, and the battery 18 is charged with this power. The restart motor 20 is provided with a rotation angle sensor 22 for detecting the rotation angle.

  As shown in FIG. 3, the ECU 30 includes an accelerator sensor 32 that detects the depression state of the accelerator pedal, a shift position sensor 33 that detects the operation position of the shift lever, and is turned on or off according to the operation of the ignition key by the driver. Each detection signal output from the ignition switch 34 that is turned OFF, the brake switch 35 that detects the depression state of the brake pedal, or the battery remaining amount sensor 36 that detects the remaining amount of the battery is input.

  The ECU 30 includes a crank angle sensor 14 for detecting the engine speed, a rotation angle sensor 22 for detecting the rotation angle of the restart motor 20, and a value relating to the in-cylinder temperature such as the engine coolant temperature or the lubricating oil temperature. The detection signals output from the engine temperature sensor 37 for detecting the in-cylinder temperature of the engine or the intake pipe negative pressure sensor 40 for detecting the negative pressure in the intake pipe are input.

  The ECU 30 includes a throttle valve control means 41 for controlling the opening degree of the throttle valve 12, a fuel injection control means 42 for controlling the injection timing and the injection amount of fuel injected from the fuel injection valve 8, and an ignition plug. 13, an ignition control means 43 for controlling the ignition timing of the air-fuel mixture, an automatic stop control means 44 for executing an automatic engine stop control, and a control signal to the inverter 22 when the engine is automatically stopped and restarted. Restart motor control means 45 for controlling the operating state of the restart motor 20 is provided.

  The throttle valve control means 41 determines the required opening of the throttle valve 12 according to the engine rotational speed calculated based on the crank angular speed information from the crank angle sensor 14, the accelerator opening information from the accelerator sensor 32, and the like. The throttle valve 12 is controlled to open and close by calculating and outputting a control signal corresponding to the calculation result to the actuator 12a.

  The fuel injection control means 42 and the ignition control means 43 include the intake air flow information detected by the air flow sensor 39 and the engine temperature detected by the engine temperature sensor 37 in addition to the accelerator opening information and engine speed information. Based on the information, etc., the required fuel injection amount, its injection timing, and the appropriate mixture ignition timing are calculated, and a control signal corresponding to the calculation result is output to the fuel injection valve 8 and the spark plug 13. Yes.

  Further, the throttle valve control means 41, the fuel injection control means 42, the ignition control means 43, and the restart motor control means 45, in addition to the above control, perform the automatic stop control means 44 described below when the engine is automatically stopped. The control corresponding to the control signal output from is executed. That is, the automatic stop control means 44 determines whether or not an automatic engine stop condition is satisfied according to output signals from the shift position sensor 33, the brake switch 35, the battery remaining amount sensor 36, and the like. Is confirmed, the fuel injection from the fuel injection valve 8 is stopped at a predetermined timing, and the ignition of the air-fuel mixture by the spark plug 13 is stopped to automatically stop the engine. ing.

  When the engine is automatically stopped by the automatic stop control means 44, a cylinder that is in an expansion stroke (hereinafter referred to as an expansion stroke cylinder) and a cylinder that is in a compression stroke (hereinafter referred to as a compression stroke cylinder) when the engine is automatically stopped. That is, the cylinders in which the intake valve 6a and the exhaust valve 7a are closed after the engine is stopped and the combustion chamber 4 is sealed are predicted and specified, and the cylinders are predetermined immediately before the engine is stopped. The fuel is injected at the timing (hereinafter referred to as pre-stop injection).

  Further, the engine is operated by applying the driving torque to the crankshaft 5 with the restart motor 20 in an operating state until the predetermined set time elapses after the automatic stop condition is satisfied and the fuel injection is stopped. Control for suppressing a decrease in the rotational speed, for example, control for maintaining the engine rotational speed at a constant value (idle rotational speed) is executed, and the throttle valve 12 is set in advance for a predetermined time shorter than the set time. The throttle valve control means 41 is configured to perform control for opening the opening.

  Further, in the present embodiment, the automatic stop control means 44 keeps the restart motor 20 in an operating state after the set time has elapsed and until the crank angle obtained in advance through experiments or the like is reached. It has become. The crank angle is such that the engine that rotates by inertia after stopping the restart motor 20 is in a state where one of the two cylinders 2 arranged in a row has one of the two cylinders 2 at the expansion stroke. It was sought after to stop.

  The automatic stop control means 44 determines whether or not the engine restart condition is satisfied according to the output signal of each sensor in the engine automatic stop state, and it is confirmed that the restart condition is satisfied. In addition, the restart motor 20 is operated, the air-fuel mixture generated by the fuel injected before the stop is ignited, and the fuel is sequentially injected into the cylinders in the intake stroke and the exhaust stroke when the engine is restarted. Thus, the engine is automatically restarted by igniting at a predetermined timing.

  When executing the engine restart control by the automatic stop control means 44, the stop duration time from the engine stop time to the restart time is measured, and the restart motor control means 45 is based on the stop duration time. Thus, the driving torque of the restart motor 20 is adjusted. That is, the time until the restart condition is satisfied after the engine is automatically stopped by the timer provided in the ECU 30 is measured as the stop duration. If this stop duration is long, In comparison, the driving torque of the restart motor 20 is set to a small value. In this way, by adjusting the drive torque of the restart motor 20 according to the stop duration time, power consumption and noise caused by unnecessary drive torque being applied to the crankshaft 5 from the restart motor 20 are reduced. While suppressing the generation, it is possible to properly restart the engine by applying a necessary driving torque.

  For example, when the engine stop duration is long, the fuel injected just before the engine stop is sufficiently vaporized or atomized, and the output torque due to the combustion of the air-fuel mixture is sufficiently obtained. By setting the driving torque of the restart motor 20 to a small value as compared with the case where the power is short, unnecessary power consumption can be suppressed. On the other hand, when the engine stop duration is short, the fuel injected or atomized just before the engine stops is insufficiently vaporized, and the output torque due to the combustion of the mixture tends to be insufficient. There is an advantage that the engine can be restarted properly by setting the driving torque of the restart motor 20 to a large value.

  Further, when it is detected that the ignition switch 34 is turned off by the driver during the automatic stop of the engine, the cylinder 2 (expansion stroke cylinder or compression stroke cylinder) immediately before the stop of the engine is detected at this time. The ignition control means 43 performs control for igniting the air-fuel mixture generated by fuel injection.

  The control operation at the time of automatic engine stop and restart executed by the engine control apparatus configured as described above will be specifically described based on the time charts shown in FIGS. In FIG. 4, the cylinders 2 are referred to as # 1 cylinder 2A, # 2 cylinder 2B, # 3 cylinder 2C, and # 4 cylinder 2D in the order of arrangement, and the engine rotation from the time when the automatic engine stop control is started. The number, the charging efficiency or the transition of the crank angle, the opening / closing of the throttle valve 12 and the timing of the operation or stop of the restart motor 20 are shown. The crank angle shown in FIG. 4 indicates the crank angle when the intake top dead center of the # 1 cylinder 2A is 0 ° CA. Further, FIGS. 4 and 5 show the case where the expansion stroke cylinder is set to the # 1 cylinder 2A.

  In the engine control apparatus, the injected fuel is cut and the ignition of the air-fuel mixture is stopped at time t0 after the automatic stop condition is satisfied. As a result, the engine starts to rotate by inertia, but at the time point t0, the operation of the restart motor 20 is also started at the same time, and the engine speed is maintained at the idle speed. Yes. Further, at the time point t0, the opening operation of the throttle valve 12 is also executed, and scavenging in each cylinder 2 is executed in combination with maintaining the engine speed by the restart motor 20. Yes.

  The throttle valve 12 is closed at a time t1 when a later-described opening time Y has elapsed from the time t0, and after the motor operating time Z has elapsed from the time t0, the motor stop crank angle CA1 (300 The driving of the restart motor 20 is stopped at the time point t2 when (CA) is reached.

  Here, the motor stop crank angle CA1 is the expansion stroke cylinder of any one of the cylinders 2 (# 1 cylinder 2A and # 4 cylinder 2D) at both ends of the row (# 1 cylinder 2A in FIG. 4). Therefore, it is a crank angle corresponding to the timing at which the restart motor 20 is stopped, which is obtained in advance through experiments or the like, and the engine speed due to the operation of the restart motor 20 (idle speed in FIG. 4). ).

  When the restart motor 20 stops at the time point t2, the engine starts to rotate by inertia and the rotational speed gradually decreases. Here, in the engine control apparatus of the present embodiment, for example, as shown at time t3 and time t4, the target engine speed L1 obtained in advance through experiments or the like is compared with the actual engine speed L2. Thus, the rotational speed deviations δ1 and δ2 are detected, and the restart motor 20 is operated so as to fill the deviations δ1 and δ2, that is, to put the actual rotational speed L2 on the target rotational speed L1. It has become.

  Further, immediately before the engine is stopped, fuel injections F1 and F2 (hereinafter referred to as pre-stop injections F1 and F2) are performed on the expansion stroke cylinder and the compression stroke cylinder, and the engine is automatically stopped and restarted. In this case, as shown in FIG. 5, the engine is restarted by sequentially igniting the air-fuel mixture generated by the fuel of these pre-stop injections F1 and F2 B1 and B2.

  FIG. 6 shows a time chart when the # 4 cylinder 2D is set as the expansion stroke cylinder. In this case, the restart motor 20 at the time point t2 when the motor stop crank angle CA2 becomes 660 ° CA. Is supposed to stop.

  In the engine control device of the present embodiment, the # 1 cylinder 2A and the # 4 cylinder 2D are alternately expanded stroke cylinders every time the engine automatic stop control is executed (that is, FIG. 4 and FIG. 4). The motor operation time Z is set so that the control 6 is executed alternately.

  Hereinafter, processing executed by the engine control device will be described with reference to the time charts of FIGS. 4 to 6 and the flowcharts of FIGS. 7 to 9.

  When this control operation is started, detection signals output from various sensors are input (step S1), and then it is determined whether or not the engine is in an automatic stop state (step S2). Determines whether or not the engine automatic stop condition is satisfied based on the detection signal (step S3). Specifically, based on the detection signals of the above various sensors, the vehicle speed is zero, the brake switch 35 remains on for a predetermined time, and the remaining battery level is equal to or higher than a predetermined reference value. If it is confirmed that the automatic stop condition of the engine is satisfied, it is determined that the automatic stop condition is not satisfied when one of the above requirements is not satisfied. It has become.

  If it is determined NO in step S3 and it is confirmed that the engine automatic stop condition is not satisfied, normal fuel injection control and ignition control are executed in accordance with the engine speed and the intake air amount ( Step S4).

  If it is determined YES in step S3 and it is confirmed that the engine automatic stop condition is satisfied, the target opening degree G of the throttle valve 12 after the fuel cut described later, its opening time Y, and after the fuel cut will be described. The control for setting the idling cycle number F is performed, and the setting time for setting the restart motor 20 in the operating state based on the idling cycle number F, that is, the control for setting the motor operating time Z is executed (step S5). .

  Next, normal fuel injection and ignition are stopped, fuel cut is performed, the throttle valve 12 is opened, the opening degree is set to the target throttle opening degree G set in step S5, and the re-opening is performed. Control is performed to maintain the engine speed at the idling speed with the starter motor 20 in the operating state (step S6: time t0). Further, it is determined whether or not the opening time Y set in step S5 has elapsed (step S7), and the throttle valve 12 is closed at a time t1 when it is determined YES (step S8). It is determined whether or not the motor operating time Z set in S5 has elapsed (step S9).

  When it is determined as YES in step S9 and it is confirmed that the motor operation time Z has elapsed, 1 is added to the counter for referring to the number of execution times of the automatic stop control (step S10) and the accumulated value is accumulated. With reference to the counter value, it is determined whether or not the current expansion cylinder is the # 1 cylinder 2A (step S11).

  In step S11 of this embodiment, specifically, when the counter value is an even number, it is determined as # 1 cylinder 2A, and when it is an odd number, it is determined as # 4 cylinder 2D. That is, every time automatic stop control is executed, # 1 is executed. The cylinder 2A or the # 4 cylinder 2B is alternately set as the expansion stroke cylinder. In step S11, each time the automatic stop control is executed once, the cylinder 2 that is the expansion stroke cylinder is changed. However, it can be changed every plural times.

  If YES in step S11, the motor stop crank angle is set to CA1 (300 ° CA) (step S12), while if NO in step S11, the motor stop crank angle is set to CA2 ( 660 ° CA) (step S13), and the crank angle sensor 14 determines whether or not the set crank angle CA1 or CA2 has arrived (step S14).

  If YES is determined in step S14, the operation of the restart motor 20 is stopped at this time t2 (step S15), and then the compression stroke cylinder is determined, and the compression stroke cylinder and the expansion stroke cylinder are determined. Fuel for restarting is injected at a predetermined timing (step S16: pre-stop injections F1 and F2 in FIGS. 4 and 5).

  In this step S16, the compression stroke cylinder can be discriminated because any one of the # 1 cylinder 2A and the # 4 cylinder 2D is set as the expansion stroke cylinder when the motor stop crank angle CA1 or CA2 is set. This is because when the expansion stroke cylinder is set to # 1 cylinder 2A, the cylinder # 3 cylinder 2C that is delayed by one cycle from the # 1 cylinder 2A is the compression stroke cylinder (FIG. 4). Similarly, when the expansion stroke cylinder is set to # 4 cylinder 2D, it can be determined that # 2 cylinder 2B is the compression stroke cylinder (see FIG. 6).

  After performing the pre-stop injections F1 and F2 immediately before stopping the engine, motor assist control described later is executed (step S17), and it is determined whether or not the engine speed N has become 0 (step S18). At time t5 when it is determined YES and it is confirmed that the engine is in the automatic stop state, the measurement of the stop duration T is started (step S19).

  On the other hand, if it is determined YES in step S2 and it is confirmed that the engine is currently in the automatic stop state, it is determined whether or not the driver has performed an OFF operation of the ignition switch 34 (step S20). . If it is determined YES in step S20 and it is confirmed that the driver has turned off the ignition switch 34 with the intention of stopping, the pre-stop injections F1, F2 are applied to the expansion stroke cylinder and the compression stroke cylinder. Is performed at the same time (step S21), the measurement value of the stop duration T is reset (step S22), and the process returns.

  If it is determined NO in step S20 and it is confirmed that the ignition switch 34 is not turned off, it is determined whether or not the engine restart condition is satisfied (step S23). As the restart condition, the brake switch 35 is turned off, the brake negative pressure (intake pipe negative pressure) is less than a predetermined value, the stop duration T is more than a predetermined value, or If the remaining battery level is less than a predetermined value or the like and one of these requirements is satisfied, it is determined that the engine restart condition is satisfied.

  If it is determined in step S23 that the engine restart condition is satisfied, the driving torque of the restart motor 20 is set by reading it from a table (step S24). The table for setting the drive torque corresponding to the measured value of the stop duration T is set based on the stop duration T. When the stop duration T is long, the drive torque is higher than when the stop duration is short. It is set to a small value. In addition, the restart motor 20 is operated at the time when the restart condition is satisfied (time t6 in the example of FIG. 5), and the air-fuel mixture generated by the pre-stop injections F1 and F2 is ignited at a predetermined timing (FIG. In the example of FIG. 5, ignition B1, B2) is executed to restart the engine (step S25).

  Then, fuel injection (cylinder 2 (# 4 cylinder 2D in the example of FIG. 5) in the intake stroke and cylinder 2 (# 2 cylinder 2B in the example of FIG. 5) in the exhaust stroke at the time t6 when the restart condition is established ( In the example of FIG. 5, fuel injections F3 and F4) are performed (step S26), and the air-fuel mixture is sequentially ignited when these cylinders 2 reach compression top dead center (ignitions B3 and B4 in the example of FIG. 5). (Step S27), the measured value of the stop duration T is reset to 0 (Step S28).

  Next, a specific example of the control for setting the target opening G, the opening time Y, the idling cycle number F, and the motor operating time Z of the throttle valve 12 executed in step S5 will be described based on the flowchart shown in FIG. To do. When the control operation starts, the intake air amount A and the allowable compression pressure B necessary for cooling each cylinder 2 are set based on the detected values of the engine temperature sensor 37 and the intake air temperature sensor 38 before the fuel cut (step S29). . The intake air amount A is the amount of intake air that passes through the cylinder 2 until the restart fuel injected before stop is supplied to the expansion stroke cylinder and the compression stroke cylinder and compressed, and the engine temperature and The higher the intake air temperature, the greater the total intake air amount A. The allowable compression pressure B is a limit pressure at which the air-fuel mixture generated by the fuel injected before stop does not self-ignite near the compression top dead center, and is a value depending on the in-cylinder temperature.

  Next, after the preset scavenging intake air amount C, that is, the last fuel injected before the fuel cut burns, the restart fuel injected before the stop is supplied to the cylinder. 2 is compared with the total intake air amount A set at step 29, and the larger one is set as the target total intake amount D (step S30).

  Further, the intake charging efficiency change pattern E is set to a value that allows the pressure in the cylinder after the fuel cut to be equal to or lower than the allowable compression pressure B obtained in step S29 and can suppress vibrations when the engine is stopped (step S29). S31). The charging efficiency change pattern E is set as described above because the intake air at the time when the cylinder (the expansion stroke cylinder and the compression stroke cylinder) into which the restart fuel is injected when the engine is automatically stopped becomes the compression top dead center. By limiting the charging efficiency to be equal to or lower than a preset upper limit value Ba (see FIGS. 4 and 6), it is possible to prevent compression self-ignition from occurring in the cylinder before the engine is stopped, and This is to prevent the driver from feeling uncomfortable due to noise and vibration.

  Next, the throttle valve 12 is opened to the target throttle opening G and the number of idling cycles F and the target throttle opening G after the fuel cut so that the target intake total amount D and the intake charging efficiency change pattern E are satisfied. The opening time Y is read from a preset map and set (step S32). As shown in FIG. 11, the map for setting the idling cycle number F after the fuel cut uses the intake charging efficiency change pattern E and the target intake total amount D as parameters, and the intake charging efficiency change pattern (filling) The efficiency change ratio (E) is set so that the idling cycle number F becomes smaller as E becomes larger, and the idling cycle number F becomes larger as the target intake total amount D becomes larger.

  As shown in FIG. 12, the target throttle opening degree G after the fuel cut uses the intake charge efficiency change pattern E and the target intake total amount D as parameters, and the intake charge efficiency change pattern (change rate of the charge efficiency). The larger the E, the larger the target throttle opening G, the larger the target intake air amount D, the larger the target throttle opening G, and the opening time Y is also set to the target throttle opening G. Similarly, the larger the intake charge efficiency change pattern (fill efficiency change rate) E, the larger the value, and the larger the target intake total amount D, the greater the value.

  Next, the restart motor 20 is operated to apply the driving torque to the crankshaft 5 so as to satisfy the number of idling cycles F after the fuel cut, that is, the restart motor 20 is operated after the fuel cut. A motor operation time Z for maintaining the engine speed at a constant value (idle speed) is calculated (step S33). Specifically, when the engine in the idle rotation state is fuel cut, the time until the engine is stopped is obtained by experiments or the like, and the motor operating time is calculated based on this time and the time corresponding to the idling cycle number F. Z is calculated.

  Next, the motor assist control executed in step S17 will be described based on FIG. 4, FIG. 6, and FIG. When the above control operation starts, the actual engine speed L2 at the time t3 and t4 when the crank angle of the cylinder 2 (# 1 cylinder 2A or # 4 cylinder 2D) set as the expansion stroke cylinder reaches a predetermined value, A rotational speed deviation δ with respect to the target rotational speed L1 obtained by experiment or the like is calculated (step S34), and a driving torque of the restart motor 20 corresponding to the rotational speed deviation δ, that is, a stop assist force is obtained ( Step S35).

  For example, as shown in FIGS. 4 and 6, the engine speed at time t3 when the crank angle of the expansion stroke cylinder (# 1 cylinder 2A or # 4 cylinder 2D) becomes 180 ° CA before compression top dead center TDC. When it is confirmed that L2 is equal to or less than the target rotational speed L1 and the rotational speed deviation δ1 at the time t3 is a negative value, in order to bring the engine rotational speed L2 closer to the target rotational speed L1, the rotational speed A positive drive torque corresponding to the deviation δ1 is set. Further, the engine speed L2 at the time t4 when the crank angle of the expansion stroke cylinder becomes the compression top dead center TDC is equal to or higher than the target speed L1, and the speed deviation δ2 at the time t4 is a positive value. If it is confirmed, the reverse drive torque (brake torque) corresponding to the deviation δ2 is input to the crankshaft 5 so that the engine speed L2 is controlled to approach the target speed L1.

  Then, by outputting an operation command signal to the restart motor 20 (step S36), after applying the stop assist force obtained in step S35 to the crankshaft 5, the crank angle of the expansion stroke cylinder is set to the target. Based on the engine speed at time t5 when the stop position (450 ° CA in FIG. 4; 90 ° CA in FIG. 6) is reached, the amount of reverse rotation of the engine that occurs at the time of stop is predicted (step S37). Thereafter, by outputting an operation command signal corresponding to the reverse rotation amount to the restart motor 20, a positive drive torque corresponding to the predicted value of the reverse rotation amount is applied to the crankshaft 5 (step S38).

  That is, when the engine is stopped, in the compression stroke cylinder (# 2 cylinder 2B or # 3 cylinder 2C), as the piston 3 approaches the top dead center, the air in the cylinder is compressed and pressure acts in a direction to push the piston 3 back. As a result, the engine reverses and the piston 3 of the compression stroke cylinder is pushed back to the bottom dead center side, and the piston 3 of the expansion stroke cylinder (# 1 cylinder 2A or # 4 cylinder 2D) moves to the top dead center side. Accordingly, the air in the cylinder is compressed, and the reverse pressure phenomenon occurs in which the piston 3 of the expansion stroke cylinder is pushed back to the bottom dead center side by the pressure. Therefore, the positive drive torque corresponding to the reverse rotation amount is applied to the crankshaft. By acting on 5, the stop position of the crankshaft 5 can be accurately matched with the target stop position. In FIG. 4 and FIG. 6, the driving of the restart motor 20 is omitted.

  Note that the drive torque applied from the restart motor 20 is controlled based on the rotational speed deviation δ between the actual engine rotational speed L2 at a predetermined time point and the target rotational speed L1 obtained in advance through experiments as described above. Thus, instead of the embodiment in which the engine is stopped when the crank angle of the expansion stroke cylinder reaches the target stop position, for example, calculation is performed according to the output signals of the air flow sensor 39 and the crank angle sensor 14. The crankshaft torque may be calculated at a predetermined timing based on the intake charging efficiency, and the driving torque applied by the restart motor 20 may be controlled based on this value.

  For example, if the expansion stroke cylinder is set to # 1 cylinder 2A (as shown in FIG. 4), as shown in FIG. 14, the expansion torque of # 1 cylinder 2A is obtained based on the intake charging efficiency. In addition, the compression torque of the # 3 cylinder 3C, the intake resistance of the # 4 cylinder 2D, the exhaust resistance of the # 2 cylinder 2B, and the mechanical resistance of the entire engine may be obtained, and these values may be calculated. The drive torque applied by the restart motor 20 may be controlled based on a deviation between the calculated value of the crankshaft torque and a preset target crankshaft torque.

  Further, as shown in FIG. 15, the peak value of the crankshaft torque is read from a preset map with the intake charging efficiency and the engine speed as parameters, and this value and the preset target crankshaft torque Based on the deviation, the driving torque applied by the restart motor 20 may be controlled.

  Further, as shown in FIG. 16, the deviation between the engine rotational speed L2 and the target rotational speed L1 is sequentially calculated from a predetermined time t3, or the deviation between the crankshaft torque and the target crankshaft torque is sequentially calculated. The engine may be stopped when the crank position of the expansion stroke cylinder reaches the target stop position by feedback control of the drive torque applied from the restart motor 20 based on the deviation of the above.

  As described above, the restart motor control means 45 for controlling the drive of the restart motor 20 during the automatic engine stop period is provided, and at least any of the ones arranged at both ends in the row of the cylinders 2. According to the above embodiment in which the restart motor control means 45 is controlled so that one of the cylinders 2 is in the expansion stroke when the engine is stopped, the expansion stroke cylinder is the one at the end of the row of each cylinder 2. Therefore, it is possible to prevent the fuel injected before the stop from being overheated excessively, and to prevent the air-fuel mixture generated by this fuel from undergoing compression self-ignition in the preceding compression stroke in the expansion stroke cylinder. Can do.

  That is, in the engine automatic stop state, heat from combustion during normal operation remains in the engine itself, and the gas in the fuel chamber 4, that is, the fuel injected before the stop is injected by heat exchange with this heat. Although the air-fuel mixture generated by the fuel is overheated, in the above embodiment, the # 1 cylinder 2A or the # 4 cylinder 2D arranged at the end of the row of each cylinder 2, that is, the other cylinder 2 Since the cylinder 2 that can dissipate the residual heat to the open side without being adjacent to both sides, the fuel is injected before stopping, so that the other cylinders 2 are adjacent to both sides. 2 (# 2 cylinder 2B, # 3 cylinder 2C), the amount of heat for the air-fuel mixture by the heat exchange can be reduced, and as a result, the air-fuel mixture in the expansion stroke cylinder can be prevented from being overheated excessively. it can.

  Therefore, according to the above embodiment, by suppressing excessive overheating of the fuel injected before stopping, compression self-ignition of the fuel before stopping before restarting the engine can be suppressed. The pre-stop injection fuel can be used effectively at the start, and the restart performance can be improved.

  The cylinder 2 as the expansion stroke cylinder may be at least one of the rows of the cylinders 2. However, as in the above-described embodiment, the # 2 cylinder 2A is It is preferable to control the restart motor control means 45 so that the # 4 cylinder 2D alternately performs an expansion stroke.

  In this way, the cylinder serving as the expansion stroke cylinder can be changed every predetermined number of executions of the automatic engine stop, so that deterioration of the performance of the spark plug 13 over time can be prevented.

  That is, in the first combustion at the time of engine restart, the combustion condition is relatively bad, and this combustion causes so-called fogging of the spark plug 13 in which foreign matter such as carbon adheres to the spark plug. Although there is a possibility that the ignition performance of the plug 13 is deteriorated due to adhesion and accumulation, according to the above configuration, the cylinder to be burned first when the engine is restarted can be changed every predetermined number of times of automatic engine stop. As a result of avoiding the overlap of the above-mentioned fog for a specific cylinder, it is possible to prevent the ignition performance of the spark plug 13 from being deteriorated.

  In the above embodiment, the engine body 1 having four cylinders 2 has been described. However, the number of cylinders is not limited to four, and at least a plurality of cylinders 2 may be arranged in a row. Good.

It is a schematic sectional drawing of the engine provided with the control apparatus which concerns on this invention. It is explanatory drawing which shows the structure of the restart apparatus of the engine of FIG. It is a block diagram which shows the specific structure of the control apparatus of the vehicle of this invention. FIG. 4 is a time chart showing the control operation of the control device of FIG. 3, showing control when the expansion stroke cylinder is set to # 1 cylinder. FIG. FIG. 4 is a time chart showing an enlarged range from engine automatic stop to restart in the control operation of the control device of FIG. 3, showing control when the expansion stroke cylinder is set to # 1 cylinder. FIG. 4 is a time chart showing the control operation of the control device of FIG. 3, showing control when the expansion stroke cylinder is set to # 4 cylinder. FIG. It is a flowchart which shows the control action of the control apparatus of FIG. 3 (1/3). It is a flowchart which shows the control action of the control apparatus of FIG. 3 (2/3). It is a flowchart which shows the control action of the control apparatus of FIG. 3 (3/3). It is a flowchart which shows the setting control operation | movement of the fuel cut rotation speed and target throttle opening of FIG. It is a graph which shows an example of the map for setting the number of idling cycles of an engine. It is a graph which shows an example of the map for setting a target throttle opening. It is a flowchart which shows the motor assist control operation | movement of FIG. It is explanatory drawing which shows the specific structure for calculating a crankshaft torque. It is a graph which shows an example of the map for calculating | requiring an axial torque peak value. It is a time chart which shows another example of motor assist control operation.

Explanation of symbols

1 Engine body 2 Cylinder 5 Crankshaft (output shaft)
20 Restart motor (motor)
45 Restart motor control means (motor control means)

Claims (2)

In a vehicle equipped with an engine in which a plurality of cylinders are arranged in a row, the fuel supply is stopped to stop the engine automatically when a preset engine automatic stop condition is satisfied, and at least the engine expands when the engine stops automatically. While fuel is injected into the cylinder in the stroke immediately before the engine is stopped, when the preset restart condition is satisfied after the engine is automatically stopped, the restart motor is activated to drive the engine output shaft. A vehicle control device that ignites the air-fuel mixture generated by the fuel injection immediately before the stop and restarts the engine,
Motor control means for controlling the driving of the restart motor during the automatic engine stop period;
A vehicle control apparatus that controls the motor control means so that at least one of the cylinders arranged at both ends in the row of cylinders is in an expansion stroke when the engine is stopped.   The motor control means controls the motor control means so that the cylinders arranged at both ends in the row of cylinders alternately perform expansion strokes at every predetermined number of executions of automatic engine stop. The vehicle control device according to claim 1, characterized in that:

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