JP2005030237A - Control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a vehicle capable of correctly restarting an engine at timing when restarting conditions are satisfied after the engine is stopped. <P>SOLUTION: This control device is provided with a fuel injection means 8 to inject fuel at least to a cylinder getting into an expansion stroke shortly before the engine is stopped when the engine is automatically stopped, an ignition control means 43 to control to ignite mixed gas generated by fuel injection shortly before stopping to restart the engine, a restarting motor 20 to drive an output shaft of the engine to restart the engine, and a restarting motor control means 45 to control to restrict lowering of engine speed by setting the restarting motor 20 in an actuation state for set time after fuel injection is stopped so that the engine is automatically stopped. Fuel injection shortly before stopping is executed after pass of the set time. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle control apparatus, and automatically stops an engine when a preset engine automatic stop condition is satisfied in an idle operation state of the engine, and restarts the engine when an engine restart condition is satisfied. The present invention relates to a control device for a vehicle configured to cause the vehicle to move.
[0002]
[Prior art]
In recent years, fuel consumption reduction and CO ₂ Automatic engine stop control that automatically stops the engine temporarily when idling, etc., and then restarts the engine automatically when a restart condition such as a start-up operation is fulfilled to reduce emissions So-called idle stop control technology has been developed. The restart at the time of the idle stop control requires a quickness to immediately start the engine in accordance with the start operation of the vehicle or the like, but the engine output by the starter motor is generally performed conventionally. According to the method of restarting the engine through cranking that drives the shaft, there is a problem that it takes a considerable time to complete the start-up.
[0003]
Therefore, as a start control device suitable for restarting the idle stop control, the operation state of the internal combustion engine satisfies the automatic stop condition during the operation of the spark ignition type internal combustion engine that forms the air-fuel mixture by the fuel injection of the fuel injection valve. In the internal combustion engine automatic stop start control device that automatically starts the internal combustion engine when the automatic start condition is satisfied, the internal combustion engine is automatically stopped immediately before the internal combustion engine is automatically stopped. In this case, by injecting fuel into the combustion chamber of a cylinder that is estimated to be in a state where both the intake valve and the exhaust valve are closed during the compression stroke, the combustion chamber of the cylinder can be spark-ignited in an automatic stop state of the internal combustion engine. There is known an air-fuel mixture state (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
JP 2001-342876 A
[0005]
[Problems to be solved by the invention]
When the engine is configured to inject fuel immediately before the engine enters the automatic stop state as disclosed in Patent Document 1, if the temperature in the cylinder is high, the air-fuel mixture generated by the fuel injection is Compressed to high temperature and high pressure and self-ignited, or the fuel injected just before the engine is automatically stopped comes into contact with a hot spark plug or exhaust valve, etc. When the surface ignition occurs, the air-fuel mixture cannot be combusted when the engine is restarted, which causes a problem that the engine cannot be restarted with the fuel of the air-fuel mixture.
[0006]
In view of the above circumstances, the present invention provides a vehicle control device that can appropriately restart an engine that has been in an automatic stop state.
[0007]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a vehicle control apparatus including automatic stop control means for automatically stopping an engine when a preset engine automatic stop condition is satisfied in an idle operation state of the engine. A fuel injection means for injecting fuel to a cylinder that is at least in an expansion stroke at the time of automatic stop, and a restart condition that is set in advance after the engine is automatically stopped. Ignition control means for controlling the engine to be restarted by igniting the air-fuel mixture generated by fuel injection, a restart motor for driving the engine output shaft to restart the engine, and for automatically stopping the engine Until the set time elapses after the fuel injection is stopped, the restart motor is operated to suppress a decrease in engine speed. And a restart motor control means for controlling the, which is constituted so as to perform fuel injection of the stop just before the after the set time.
[0008]
According to this configuration, until the set time elapses after the automatic stop condition is satisfied and the fuel injection is stopped, the restart motor is in an operating state to suppress a decrease in the engine speed, Compressed self-ignition of the air-fuel mixture generated by injecting fuel into the cylinder immediately before the engine stops because a sufficient amount of intake air passing through the cylinder after the fuel injection is stopped and the temperature in the cylinder decreases. And the hot surface ignition of the fuel is effectively prevented.
[0009]
According to a second aspect of the present invention, in the vehicle control device according to the first aspect, the engine speed is kept at a constant value until a set time elapses after the fuel injection is stopped when the automatic stop condition is satisfied. Thus, the driving torque of the restart motor is controlled so as to be maintained.
[0010]
According to this configuration, until the set time elapses after the automatic stop condition is satisfied and the fuel injection is stopped, the restart motor is operated and the control for maintaining the engine speed at a constant value is executed. As a result, the amount of intake air that passes through the cylinder after the fuel injection is stopped is appropriately controlled.
[0011]
According to a third aspect of the present invention, in the vehicle control apparatus according to the first or second aspect, the remaining battery level detecting means for detecting the remaining battery level for supplying power to the restart motor, and the remaining battery level And an engine speed increasing means for temporarily increasing the engine speed when the restart condition is satisfied when the reference value is smaller than a preset reference value.
[0012]
According to this configuration, when it is confirmed that the remaining battery level is low when the automatic stop condition is satisfied, control is executed to temporarily increase the engine speed and increase the number of idling cycles of the engine. Without setting the restart motor driving torque to a large value, it is possible to effectively reduce the in-cylinder temperature by sufficiently securing the intake air amount that passes through the cylinder after the fuel injection is stopped. .
[0013]
According to a fourth aspect of the present invention, in the vehicle control apparatus according to the third aspect, the remaining battery amount detecting means detects the number of idling cycles of the engine after the stop of fuel injection to a target value. The set time for the restart motor to be activated is changed in accordance with the remaining battery level.
[0014]
According to this configuration, it is possible to prevent a situation in which the number of idling cycles is insufficient due to a low remaining battery level when the automatic stop condition is satisfied, and to ensure a sufficient amount of intake air passing through the cylinder. become.
[0015]
According to a fifth aspect of the present invention, in the vehicle control device according to any one of the first to fourth aspects, the throttle valve is provided for a predetermined period after the fuel injection is stopped when the automatic stop condition is satisfied. Throttle valve control means for opening control is provided.
[0016]
According to this configuration, until the set time elapses after the automatic stop condition is satisfied and the fuel injection is stopped, the restart motor is operated to suppress the decrease in the engine speed. When this control is executed, the throttle valve is opened for a predetermined period and a large amount of intake air is introduced into the cylinder, so that the in-cylinder temperature can be effectively reduced.
[0017]
The present invention according to claim 6 is the vehicle control apparatus according to claim 5, further comprising in-cylinder temperature detecting means for detecting a value related to an in-cylinder temperature of the engine, wherein the throttle is increased as the in-cylinder temperature of the engine is higher. The opening degree of the valve is configured to be set to a large value.
[0018]
According to this configuration, when the automatic stop is performed in a state where the engine cylinder temperature is high, the throttle valve opening degree is controlled when the restart motor is operated to suppress the decrease in the engine speed. Is set to a large value and a large amount of intake air is introduced into each cylinder, so that the in-cylinder temperature can be significantly reduced.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
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 a plurality of cylinders 2, and a piston 3 is fitted into each cylinder 2, so that a combustion chamber 4 is formed above the cylinder 3. The piston 3 is connected to the crankshaft 5 via a connecting rod (not shown).
[0020]
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. This fuel injection valve 8 incorporates a needle valve and a solenoid (not shown), 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.
[0021]
The intake / exhaust ports 6 and 7 are equipped with an intake valve 6a and an exhaust valve 7b, respectively. These intake valve 6a and exhaust valve 7a are driven by a valve operating mechanism having a camshaft or the like. The opening / closing timings of the intake / exhaust valves 6a and 7a of each cylinder 2 are set so that each cylinder 2 performs a combustion cycle with a predetermined phase difference.
[0022]
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.
[0023]
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 an engine restarting device at the other end. Is arranged. 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.
[0024]
The restart motor 20 is activated to rotate the crankshaft 5 in response to a control signal output from the ECU (engine control unit) 30 described below when the engine is restarted. The restart motor 20 is provided with a rotation angle sensor 22 for detecting the rotation angle.
[0025]
As shown in FIG. 3, the ECU 30 includes an accelerator sensor 32 for detecting the depression state of the accelerator pedal, a shift position sensor 33 for detecting the operation position of the shift lever, and ON 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, and the battery remaining amount sensor 36 that detects the remaining amount of the battery according to the battery voltage is input. It has come to be.
[0026]
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 an in-cylinder temperature such as an engine coolant temperature or a lubricating oil temperature. Engine temperature sensor 37 for detecting the temperature in the cylinder of the engine based on the value relating to the above, an intake air temperature sensor 38 for detecting the intake air temperature, an air flow sensor 39 for detecting the intake air flow rate, and an intake pipe for detecting the negative pressure in the intake pipe Detection signals respectively output from the negative pressure sensor 40 are input.
[0027]
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.
[0028]
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.
[0029]
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 and the like, a required fuel injection amount, its injection timing, and an 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.
[0030]
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 automatic stop control means described below when performing automatic engine stop control. The control corresponding to the control signal output from 44 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. When it is confirmed that the above condition is established, 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. Has been.
[0031]
When the engine is automatically stopped by the automatic stop control means 44, the cylinders that are in the expansion stroke and the compression stroke when the engine is automatically stopped, that is, the intake valve 6a and the exhaust valve 7b are closed after the engine is stopped. Thus, the cylinders in which the combustion chamber 4 is sealed are predicted and specified, and control for injecting fuel to these cylinders at a predetermined timing immediately before the engine is stopped is executed.
[0032]
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 the 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 execute the control for opening to a predetermined opening degree.
[0033]
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 cylinder that is in the intake stroke and the exhaust stroke when the restart motor 20 is operated and the air-fuel mixture generated by the fuel being injected into the cylinder immediately before the engine is stopped is restarted. The engine is automatically restarted by injecting fuel sequentially and igniting at a predetermined timing.
[0034]
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, and when this stop duration is long, it is shorter than when it is short. Thus, the driving torque of the restart motor 20 is set to a small value.
[0035]
Further, when it is detected that the ignition switch 34 is turned off by the driver during the automatic engine stop, the fuel is generated by injecting fuel into the cylinder immediately before the engine is stopped. The ignition control means 43 is configured to execute control for igniting the air-fuel mixture.
[0036]
The engine control operation executed by the engine control apparatus configured as described above will be described based on the flowcharts shown in FIGS. 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 various sensors, the vehicle speed is zero, the ON state of the brake switch 35 continues for a predetermined time, and the remaining battery level is equal to or higher than a preset first 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.
[0037]
When 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 according to the engine speed and the intake air amount ( Step S4).
[0038]
If it is determined YES in step S3 and it is confirmed that the engine automatic stop condition is satisfied, the target opening (target throttle opening) G of the throttle valve 12 after fuel cut, which will be described later, and its opening are opened. Control for setting the time Y and the number of idling cycles F of the engine after the fuel cut is performed, and the setting time for setting the restart motor 20 in the operating state based on the number of idling cycles F, that is, control for setting the motor operating time Z Is executed (step S5).
[0039]
Next, normal fuel injection and ignition are stopped to cut the fuel, and the throttle valve 12 is opened to set the opening to the target throttle opening G set in step S5, and the restart motor 20 is turned on. As an operation, control for maintaining the engine speed at the idle speed is executed (step S6). Further, it is determined whether or not the opening time Y set in step S5 has elapsed (step S7). When it is determined YES, the throttle valve 12 is closed (step S8), and then the above step is performed. It is determined whether or not the motor operating time Z set in S5 has elapsed (step S9).
[0040]
If it is determined YES in step S9 and it is confirmed that the motor operation time Z has elapsed, the operation of the restart motor 20 is stopped at this time (step S10), and then the engine speed N is It is determined whether or not the reference rotational speed R is set based on an experiment or the like conducted in advance to identify a cylinder that is in the expansion stroke and a cylinder that is in the compression stroke when the engine is automatically stopped (step S11).
[0041]
When it is determined YES in step S11 and it is confirmed that the rotation speed N has reached the reference rotation speed R, the cylinder that is in the expansion stroke and the cylinder that is in the compression stroke when the engine is automatically stopped is determined. Immediately before stopping, the fuel for restarting is injected at a predetermined timing into the cylinder that is in the expansion stroke and the cylinder that is in the compression stroke when the engine is automatically stopped (step S12).
[0042]
For example, as shown in FIGS. 7 and 8, there are 4 cylinders having a first cylinder to a fourth cylinder, in which combustion is performed in the order of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder. In a cylinder four-cycle engine, when it is confirmed by an experiment that the engine stops about 2 rotations after the rotation speed N reaches 500 rpm, the reference rotation speed R is set to 500 rpm. The first cylinder that is in the expansion stroke at the time point t0 is specified as the cylinder that is in the expansion stroke when the engine is automatically stopped, and the third cylinder that is in the compression stroke at the time point is the compression stroke when the engine is automatically stopped. Specified as a cylinder. Then, after the time point t1 when the crank angle of the first cylinder reaches 540 ° (ATDC-540 deg) before the compression top dead center TDC, fuel injection F1 to the intake port of the first cylinder is performed, and the crank angle is After the time t2 when the angle reaches 360 °, fuel injection F2 is performed on the intake port of the third cylinder.
[0043]
The cylinders that are in the expansion stroke at the time of the automatic engine stop are determined by determining the cylinders that are in the expansion stroke at the time t0 when the engine rotation speed N becomes the reference rotation speed R set based on the experiment conducted in advance. Instead of the above-described configuration, the rotational energy is calculated from the rotational speed of the crankshaft 5 when the engine rotational speed N reaches a predetermined value, and this rotational energy and one stroke of each cylinder (the crankshaft The amount of rotation from the time t0 to the time when the engine stops may be obtained by calculation based on the loss energy lost during the rotation of 5 by 180 °. The loss energy is obtained by adding the pumping loss of the engine, the mechanical resistance of the rotating portion, and the loss due to compression leakage of each cylinder.
[0044]
After performing the fuel injections F1 and F2 immediately before stopping the engine in step S12, it is determined whether or not the engine speed N has become 0 (step S13), and YES is determined and the engine is automatically stopped. At the time t3 when it is confirmed that the above has been confirmed, the measurement of the stop duration T is started (step S14).
[0045]
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 S16). . If it is determined YES in step S16 and it is confirmed that the driver has turned off the ignition switch 34 with the intention of stopping, the first cylinder and the compression stroke that are in the expansion stroke when the engine is automatically stopped. And simultaneously igniting the air-fuel mixture generated by performing the fuel injections F1 and F2 on the third cylinder (step S17), and resetting the measured value of the stop duration T (step S18). Return.
[0046]
If it is determined NO in step S16 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 S19). 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 the first reference value and one of these requirements is satisfied, it is determined that the engine restart condition is satisfied.
[0047]
If it is determined in step S19 that the engine restart condition is satisfied, the driving torque of the restart motor 20 is set by reading from the table (step S20). 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 point t4 when the restart condition is satisfied, and ignition S1 is performed at a predetermined timing with respect to the air-fuel mixture generated by the fuel being injected into both the cylinders immediately before the engine is stopped. , S2 is performed to restart the engine (step S21).
[0048]
Then, fuel injections F3 and F4 are performed on the fourth cylinder in the intake stroke and the second cylinder in the exhaust stroke at time t4 when the restart condition is satisfied (step S22), and these cylinders become compression top dead centers. After the ignition of the air-fuel mixture S3 and S4 is sequentially performed at the time (step S23), the measured value of the stop duration T is reset to 0 (step S24).
[0049]
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 1 executed in step S5 will be described based on the flowchart shown in FIG. To do. When the control operation starts, the total intake air amount A and the allowable compression pressure B necessary for cooling the cylinder 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 S31). The total intake air amount A is the intake air amount that passes through the cylinder until the restart fuel injected after the fuel cut is supplied to the cylinder and compressed, and the higher the engine temperature and the intake air temperature, The intake air total amount A is also a large value. The allowable compression pressure B is a limit pressure at which the air-fuel mixture generated by injecting the restarting fuel after the fuel cut does not self-ignite near the compression top dead center, and reaches the in-cylinder temperature. It is a dependent value.
[0050]
Next, after the preset scavenging intake air amount C, that is, the last fuel injected before the fuel cut is burned, the restart fuel injected before the engine is stopped is supplied to the cylinder. The intake air amount C passing through the cylinder is compared with the total intake air amount A set in step S31, and the larger one is set as the target intake total amount D (step S32).
[0051]
Further, the intake air 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 S31 and that can suppress vibration when the engine is stopped (step S33). ). The charging efficiency change pattern E is set as described above because the intake charging efficiency at the time when the cylinder in which the restart fuel is injected at the time of automatic engine stop becomes the compression top dead center By limiting the value to be equal to or less than the value Ba, it is possible to prevent compression self-ignition from occurring in the cylinder before stopping the engine and to prevent the driver from feeling uncomfortable due to engine noise and vibration. .
[0052]
Further, the number of idling cycles F and the target throttle opening G after the fuel cut and the opening for opening the throttle valve 12 to the target throttle opening G so as to satisfy the target total intake amount D and the charging efficiency pattern E of the intake air are satisfied. The time Y is read from a preset map and set (step S34). As shown in FIG. 10, the map for setting the number of idling cycles F after the fuel cut has an intake charge efficiency pattern E and a target intake total amount D as parameters, and an intake charge efficiency pattern (of the charge efficiency). The change rate is set such that the greater the E, the smaller the idle cycle number F, and the greater the target intake total amount D, the greater the idle cycle number F.
[0053]
As shown in FIG. 11, the target throttle opening degree G after the fuel cut uses the intake charge efficiency pattern E and the target intake total amount D as parameters, and the intake charge efficiency pattern (fill efficiency change rate) E is The larger the throttle opening G is, the larger the throttle opening G is. The larger the target intake total amount D is, the larger the target throttle opening G is, and the opening time Y is the same as the target throttle opening G. The charging efficiency pattern (change rate of charging efficiency) E is set to be larger as the charging efficiency pattern E is larger, and is set to be larger as the target intake total amount D is larger.
[0054]
Next, the engine is operated by operating the restart motor 20 to operate the restart motor 20 so as to satisfy the number F of idle cycles after the fuel cut, that is, after the fuel cut, by operating the restart motor 20 after the fuel cut. A motor operating time Z for maintaining the rotational speed at a constant value (idle rotational speed) is calculated (step S35). Specifically, when the engine in the idling state is cut off, the time until the engine is stopped is obtained by an experiment or the like, and the motor operation is performed based on this time and the time corresponding to the idling cycle number F. Time Z is calculated.
[0055]
In the vehicle control device having the automatic stop control means 44 for automatically stopping the engine when a preset engine automatic stop condition is satisfied in the engine idling state as described above, the vehicle control device has a small amount when the engine is automatically stopped. The fuel injection means comprising a fuel injection valve 8 that injects fuel to the cylinder that is originally in the expansion stroke immediately before the engine is stopped, and the above-mentioned stop when a preset restart condition is established after the engine is automatically stopped Ignition control means 43 for controlling the engine to be restarted by igniting the air-fuel mixture generated by the immediately preceding fuel injection, the restart motor 20 for driving the engine crankshaft 5 to restart the engine, and the engine Until the set time elapses after the fuel injection is stopped to automatically stop the operation of the restart motor 20. And a restart motor control means 45 for controlling the reduction of the engine speed, and the fuel injection immediately before the stop is performed after the set time has elapsed. It is possible to effectively prevent the compression self-ignition of the air-fuel mixture generated by injecting the fuel and the hot surface ignition of the fuel.
[0056]
That is, as shown in FIG. 12, at the time ta when the engine automatic stop condition is satisfied, the fuel is cut, and the driving torque is input from the restart motor 20 to the output shaft (crankshaft 5) of the engine. Since the reduction of the rotational speed N is suppressed, the idling cycle number F from the fuel cut time ta to the time t3 when the engine is stopped is maintained at a predetermined value, and is introduced into the cylinder during this period. The in-cylinder temperature can be lowered by securing the intake air amount. Therefore, it is possible to effectively prevent the air-fuel mixture generated by performing the fuel injections F1 and F2 immediately before the engine is stopped from being subjected to compression self-ignition or hot surface ignition, and the above-mentioned mixing is performed when the engine is restarted. There is an advantage that the engine can be restarted quickly and appropriately in accordance with the combustion energy obtained by igniting the engine and the driving force applied from the restart motor 20 to the engine crankshaft 5.
[0057]
In the above embodiment, the engine speed N is set to a constant value, that is, the idling speed from the time ta when the fuel injection is stopped when the automatic stop condition is satisfied to the time tb when the set time (motor operating time Z) elapses. Since the driving torque of the restart motor 20 is controlled so as to be maintained, the intake air amount introduced into the cylinder in order to lower the in-cylinder temperature can be easily and appropriately secured.
[0058]
Further, in the above embodiment, the throttle valve 12 is opened so that the opening degree of the throttle valve 12 becomes a preset target throttle opening degree G for a predetermined time Y from the time point ta when the fuel cut is performed. Since the intake air flow introduced into each cylinder is increased, the intake air amount introduced into the cylinder after the fuel cut can be sufficiently secured to effectively reduce the in-cylinder temperature. There is an advantage that the time required to reach the stop state can be shortened as much as possible.
[0059]
In particular, as shown in the above embodiment, the target throttle opening G after the fuel cut is changed to a target intake total amount D and an intake air amount that change according to a value related to the in-cylinder temperature such as the engine coolant temperature or the lubricating oil temperature. When the target intake total amount D is large and the change rate of the intake charge efficiency is large due to a high in-cylinder temperature, the target throttle opening G is set to a large value. When configured so as to introduce a large amount of intake air into each cylinder after the fuel cut to effectively reduce the temperature in the cylinder, it is possible to reliably prevent compression self-ignition and the like of the air-fuel mixture. There is.
[0060]
Further, as shown in the above embodiment, when the intake charging efficiency pattern E is set so that the cylinder pressure after the fuel cut is equal to or lower than the allowable compression pressure B obtained in step S31. Since the internal pressure of the cylinder in which the fuel is injected immediately before the engine is stopped can be prevented from rising excessively, the mixture generated by the fuel being injected into the cylinder immediately before the engine is stopped is compressed. There is an advantage that self-ignition can be prevented more effectively. Specifically, as shown in FIG. 13, the intake charging efficiency at the time point tc when the cylinder in which the fuel injections F1 and F2 are performed immediately before the engine is stopped becomes the compression top dead center is equal to the allowable compression pressure B. By configuring the intake air filling efficiency pattern E so as to be equal to or less than the corresponding value Ba, the compression self-ignition can be effectively prevented.
[0061]
In the above-described embodiment, the example in which the engine speed N is maintained at a constant value until the set time (motor operating time Z) elapses from the fuel cut time ta has been described. Thus, after executing the control to temporarily increase the engine speed N as necessary at the time t when the engine restart condition is satisfied, the fuel is cut and the restart motor 20 is operated to operate the engine. You may comprise so that the fall of the rotation speed N may be suppressed.
[0062]
That is, when it is determined YES in step S3 of the flowchart shown in FIG. 4 and it is confirmed that the automatic stop condition is satisfied, the remaining battery level V detected by the remaining battery level sensor 36 as shown in FIG. Is less than or equal to a second reference value preset to a value larger than the first reference value (step S41). If NO is determined, the process proceeds to step S5 in FIG. Then, 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 1 is executed.
[0063]
If it is determined YES in step S41 and it is confirmed that the remaining battery level V is equal to or smaller than the second reference value, the throttle opening is set to a predetermined constant opening W, and this is handled accordingly. Then, control is performed to temporarily increase the engine speed by increasing the fuel injection amount (step S42), and the target of the throttle valve 12 after the fuel cut is performed in the same manner as in step S5 of the flowchart shown in FIG. Control for setting the throttle opening G, the opening time Y, and the idling cycle number F of the engine is executed (step S43).
[0064]
Next, based on the remaining battery level detected by the remaining battery level sensor 36 and the idling cycle number F set in step S43, the fuel cut is performed after the engine speed increase control is executed. An engine speed (fuel cut speed) H at which the engine is stopped after the engine has been rotated by the number of cycles F and a motor operating time Z for maintaining the restart motor 20 in the operating state after the fuel cut are obtained. (Step S44).
[0065]
Then, it is determined whether or not the engine speed N has reached the fuel cut speed H (step S45). At a time ta when it is determined YES, the throttle valve 12 is opened and the opening degree is set to the step S43. The target throttle opening G set in step S1 is set, and the restart motor 20 is operated to suppress the decrease in the engine speed (step S46). Then, the process proceeds to step S7 in FIG.
[0066]
The battery remaining amount detecting means 36 for detecting the remaining amount of the battery 18 that supplies power to the restart motor 20 as described above, and the restart when the remaining battery amount V is smaller than a preset second reference value. When the condition is satisfied, the opening of the throttle valve 12 is increased to a predetermined constant value, and the fuel injection amount is increased to maintain the air / fuel ratio constant (theoretical air / fuel ratio) correspondingly. Since the control for temporarily increasing the rotational speed is performed by the rotational speed increasing means including the throttle valve control means 41 and the fuel injection control means 42, the restart motor 20 is controlled when the remaining battery level is low. Without setting the driving torque to a large value, the number of idling cycles F after stopping the fuel injection is set to a sufficient value so that the amount of intake air passing through the cylinder is sufficient. It is possible to reduce the cylinder temperature effectively by ensuring.
[0067]
In addition, the set time during which the restart motor 20 is operated according to the remaining battery level detected by the remaining battery level detecting means 36 so that the engine idling cycle number F after the stop of the fuel injection becomes the target value. In the case of changing the (motor operating time Z), it is possible to prevent the occurrence of a situation where the number of idling cycles F is insufficient due to a low battery remaining amount, and the amount of intake air passing through the cylinder By ensuring sufficient, the in-cylinder temperature can be effectively reduced.
[0068]
Further, when it is confirmed that the remaining battery level V is smaller than the preset second reference value when the automatic stop condition is satisfied, the fuel injection is performed after executing the control for temporarily increasing the engine speed. According to the above-described configuration in which the throttle valve 12 is controlled to be opened for a predetermined period Y, after the automatic stop condition is satisfied and fuel injection is stopped, the set time (motor operating time Z) elapses. During this time, the restart motor 20 is operated to suppress the decrease in engine speed while the throttle valve 12 is kept open for a predetermined period Y during the execution of the control so that a large amount of intake air enters the cylinder. By introducing, the in-cylinder temperature can be effectively reduced.
[0069]
In the above embodiment, since the restart motor control means 45 that adjusts the driving torque of the restart motor 20 according to the stop duration T from the engine stop time to the restart time is provided, the mixture is ignited. There is an advantage that the engine can be restarted quickly and properly according to the combustion energy obtained by the above and the driving force applied from the restart motor 20 to the engine crankshaft 5.
[0070]
In other words, the state of the air-fuel mixture generated by injecting fuel to the cylinders that are in the expansion stroke and compression stroke when the engine is automatically stopped immediately before the engine is stopped continues from the engine stop point to the restart point. Since it changes corresponding to the time T, the restart motor control means 45 executes control for adjusting the drive torque of the restart motor 20 in response to this, so that an unnecessary drive torque is generated from the restart motor 20. Is applied to the crankshaft 5 of the engine, and the engine can be restarted properly by applying the necessary driving torque while preventing the consumption of electric power and the generation of noise.
[0071]
For example, when the engine stop duration T is long, the fuel injected just before the engine stop is sufficiently vaporized and 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 to a smaller value than when T is short, unnecessary power consumption can be suppressed. On the other hand, when the engine stop duration T is short, the fuel injected just before engine stop is insufficiently vaporized and atomized, and the output torque due to combustion of the air-fuel 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.
[0072]
Further, in the above embodiment, when a preset automatic stop condition is satisfied, the engine is stopped while the ignition switch 34 is in the ON state, and the cylinder that is in the expansion stroke and the cylinder that is in the compression stroke when the engine is automatically stopped are Both are provided with an automatic stop control means 44 for controlling the fuel to be injected immediately before the engine is stopped, and it is detected that the ignition switch 34 is turned OFF by the driver during the automatic stop control of the engine. In this case, since the mixture generated by injecting fuel into both the cylinders at this time is combusted at the same time, unburned gas is discharged to the outside without causing significant torque fluctuations. There is an advantage that it can be prevented.
[0073]
In other words, when it is confirmed that the driver has turned off the ignition switch 34 after the engine is automatically stopped, the fuel is generated by injecting fuel into the both cylinders while the engine is automatically stopped. Since the air-fuel mixture is ignited and combusted at the same time, the output torque generated by the fuel in both cylinders acts so as to cancel each other, thereby preventing significant torque fluctuations and preventing unburned gas from being generated. Emissions can be prevented and deterioration of emissions can be prevented.
[0074]
As mentioned above, although one Embodiment of this invention was described, the specific structure of the apparatus of this invention is not limited to the said embodiment, A various change is possible within a claim. For example, the engine may be restarted by driving the crankshaft by a power transmission mechanism including a pinion provided on the output shaft of the restart motor and a startering gear provided on the crankshaft. Further, in place of the above-described embodiment in which fuel is injected just before the engine is stopped for the cylinders that are in the expansion stroke and the compression stroke when the engine is automatically stopped, only for the cylinders that are in the expansion stroke when the engine is automatically stopped. You may make it inject a fuel.
[0075]
In the above embodiment, the intake port injection type engine configured to inject fuel from the fuel injection valve 8 to the intake port 6 has been described. However, direct injection that directly injects fuel into the combustion chamber 4 of each cylinder 2 is described. The present invention can also be applied to a type of engine. The intake port injection engine does not require a high-pressure pump for supplying high-pressure fuel, and therefore has an advantage that the structure can be simplified compared to the direct injection type. In addition, by injecting fuel immediately before the engine is stopped as described above, it is possible to generate an air-fuel mixture at least in the cylinder in the expansion stroke when the engine is automatically stopped.
[0076]
【The invention's effect】
As described above, the present invention provides a vehicle control apparatus including an automatic stop control unit that automatically stops an engine when a preset engine automatic stop condition is satisfied in an idle operation state of the engine. Fuel injection means for injecting fuel to a cylinder that is at least at the expansion stroke when stopped, and fuel immediately before the stop when a preset restart condition is satisfied after the engine is automatically stopped Ignition control means for controlling the engine to be restarted by igniting the air-fuel mixture generated by injection, a restart motor for driving the engine output shaft to restart the engine, and for automatically stopping the engine Until the set time elapses after the fuel injection is stopped, the restart motor is operated to suppress a decrease in engine speed. And a restarting motor control means that controls the fuel injection immediately before the stop after the set time elapses, so that the air-fuel mixture generated by the fuel injection immediately before the engine stops is compressed by itself. There is an advantage that ignition and hot surface ignition can be effectively prevented, and the engine can be restarted properly when the engine is restarted.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an engine provided with a control device according to the present invention.
FIG. 2 is an explanatory diagram showing a configuration of the engine restart device.
FIG. 3 is a block diagram showing a specific configuration of a vehicle control apparatus according to the present invention.
FIG. 4 is a flowchart showing a first half of a control operation of the control device.
FIG. 5 is a flowchart showing an intermediate part of the control operation of the control device.
FIG. 6 is a flowchart showing the second half of the control operation of the control device.
FIG. 7 is a time chart showing a control operation of the control device.
FIG. 8 is a time chart showing a change state of the engine speed.
FIG. 9 is a flowchart showing a setting control operation of a fuel cut speed and a target throttle opening.
FIG. 10 is a graph showing an example of a map for setting the number of idling cycles of the engine.
FIG. 11 is a graph showing an example of a map for setting a target throttle opening.
FIG. 12 is a time chart showing an example of an engine stop operation.
FIG. 13 is a time chart showing another example of the engine stop operation.
FIG. 14 is a flowchart showing another example of the control operation of the control device.
[Explanation of symbols]
5 Crankshaft (output shaft)
8 Fuel injection valve (fuel injection means)
12 Throttle valve
20 Restart motor
36 Battery level sensor (Battery level detection means)
37 Engine temperature sensor (in-cylinder temperature detection means)
41 Throttle valve control means
42 Fuel injection control means (engine speed increasing means)
43 Ignition control means
44 Automatic stop control means
45 Restart motor control means

Claims (6)

In a vehicle control device provided with an automatic stop control means for automatically stopping an engine when a preset engine automatic stop condition is satisfied in an engine idle operation state, at least an expansion stroke is required when the engine is automatically stopped. A fuel injection means for injecting fuel to the cylinders immediately before the engine stops, and an air-fuel mixture generated by the fuel injection immediately before the stop when a preset restart condition is established after the engine is automatically stopped. Ignition control means for controlling ignition to restart the engine, a restart motor for driving the engine output shaft to restart the engine, and setting after fuel injection is stopped to automatically stop the engine Until the time elapses, the restart motor is controlled so as to suppress the decrease in the engine speed by setting the restart motor in an operating state. And a control means, the control device for a vehicle, characterized by being configured to perform the fuel injection of the stop just before the after the set time. The drive torque of the restart motor is controlled so as to maintain the engine speed at a constant value until a set time elapses after the fuel injection is stopped when the automatic stop condition is satisfied. The vehicle control device according to claim 1. Battery remaining amount detecting means for detecting the remaining amount of battery that supplies power to the restart motor, and when the remaining amount of battery is less than a preset reference value, the engine speed is temporarily set when the restart condition is satisfied. The vehicle control device according to claim 1, further comprising an engine speed increasing means for increasing the engine speed. The setting time for operating the restart motor is changed according to the remaining battery level detected by the remaining battery level detecting means so that the number of idling cycles of the engine after the stop of fuel injection becomes the target value. The vehicle control device according to claim 3. The vehicle according to any one of claims 1 to 4, further comprising throttle valve control means for controlling the throttle valve to open for a predetermined period after fuel injection is stopped when the automatic stop condition is satisfied. Control device. 6. An in-cylinder temperature detecting means for detecting a value related to an in-cylinder temperature of the engine is provided, and the opening degree of the throttle valve is set to a larger value as the in-cylinder temperature of the engine is higher. The vehicle control device described in 1.

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