JP2005030236A - Control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of a vehicle capable of properly re-starting an engine when requirements for re-starting are satisfied after the engine is stopped. <P>SOLUTION: This control device of the vehicle having an automatic stop control means 44 which automatically stops the engine when the requirements for the automatic stop of the engine pre-set in the idle operating state of the engine are satisfied comprises a fuel injection valve 8 injecting a fuel into a cylinder which comes at least into an expansion stroke when the engine is automatically stopped immediately before the engine is stopped, an ignition control means 43 controlling to re-start the engine by igniting to an air-fuel mixture generated by fuel injection immediately before the stoppage of the engine when the requirements for the restarting pre-set after the automatic stop of the engine, and rotational speed raising means 41 and 42 temporarily raising the rotational speed of the engine when the requirements for the automatic stop are satisfied. After the control for raising the rotational speed is completed, the fuel injection immediately before the stop of the engine is performed. Since the engine rotational speed is raised temporarily, the intake amount passing the inside of the cylinder after the stop of the fuel injection can be sufficiently secured and a temperature in the cylinder can be lowered. <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 that automatically stops the internal combustion engine when the automatic start condition is satisfied, the internal combustion engine is automatically stopped immediately before the automatic stop of the internal combustion engine. By injecting fuel into the combustion chamber of the cylinder that is estimated to be in a state where both the intake valve and the exhaust valve are closed, the combustion chamber of the cylinder is brought into an air-fuel mixture state that can be spark-ignited in an automatic stop state of the internal combustion engine. What was made is known (for example, refer to 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. Fuel injection means for injecting fuel immediately before the engine stops to the cylinder that is at least in the expansion stroke at the time of automatic stop, and fuel injection immediately before the stop when a preset restart condition is established after the engine is automatically stopped Ignition control means for controlling the air-fuel mixture generated by the engine to ignite and restart the engine, and rotation speed increasing means for temporarily increasing the engine speed when the automatic stop condition is satisfied. The fuel injection immediately before the stop is performed after the increase control of the number is completed.
[0008]
According to this configuration, when the automatic stop condition is satisfied, the engine speed is temporarily increased to execute the control to increase the idling cycle of the engine, so that the amount of intake air passing through the cylinder after the fuel injection is stopped is reduced. Since the cylinder temperature is sufficiently secured and the temperature in the cylinder is lowered, the compression self-ignition of the air-fuel mixture generated by injecting the fuel into the cylinder immediately before the engine is stopped and the hot surface ignition of the fuel are effectively prevented. It will be.
[0009]
According to a second aspect of the present invention, in the vehicle control device according to the first aspect, after the engine speed is temporarily increased when the automatic stop condition is satisfied, the throttle valve is controlled to be opened for a predetermined period. Throttle valve control means is provided.
[0010]
According to this configuration, since the throttle valve is opened and the intake air is introduced into each cylinder while the engine speed is increased, the in-cylinder temperature can be effectively reduced.
[0011]
According to a third aspect of the present invention, there is provided the vehicle control device according to the second aspect, 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 of the valve is set to a large value.
[0012]
According to this configuration, if the engine cylinder temperature is high when the automatic stop condition is satisfied, the throttle valve opening is set to a large value and a large amount of intake air is introduced into each cylinder. Can be significantly reduced.
[0013]
According to a fourth aspect of the present invention, in the vehicle control device according to the first aspect, after the fuel injection to each cylinder is stopped when the automatic stop condition is satisfied, the opening of the throttle valve is temporarily increased. The throttle valve is closed before the fuel injection immediately before the stop is performed.
[0014]
According to this configuration, after the fuel injection is stopped to automatically stop the engine, a large amount of intake air is introduced into each cylinder by temporarily increasing the opening of the throttle valve. Can be effectively reduced, and the time required for the engine to stop can be shortened.
[0015]
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).
[0016]
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.
[0017]
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.
[0018]
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.
[0019]
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.
[0020]
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.
[0021]
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.
[0022]
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.
[0023]
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, ignition control means 43 for controlling the ignition timing of the air-fuel mixture, automatic stop control means 44 for executing automatic engine stop control, and output of the inverter 22 control signal when the engine is restarted. A restart motor control means 45 for controlling the operating state is provided.
[0024]
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.
[0025]
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.
[0026]
The throttle valve control means 41, the fuel injection control means 42, and the ignition control means 43, in addition to the above control, perform control signals output from the automatic stop control means 44 described below when performing automatic engine stop control. The control corresponding to 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 condition is satisfied, 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 ignition plug 13 is stopped to automatically stop the engine. It is configured.
[0027]
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.
[0028]
In addition, when the automatic stop condition is satisfied, the opening of the throttle valve 12 is increased to a predetermined constant value, and the fuel injection amount is set to keep the air-fuel ratio constant (theoretical air-fuel ratio) correspondingly. Control for increasing the engine speed temporarily by increasing the engine speed is executed by a speed increasing means comprising the throttle valve control means 41 and the fuel injection control means 42. Further, based on the engine coolant temperature, the intake air temperature, and the like, the fuel cut rotational speed for automatically stopping the engine and the subsequent throttle opening are obtained, and based on these, the stop position of the crankshaft 5 is determined as the target stop position. In addition, the control for introducing the intake air into each cylinder is executed in the automatic stop control means 44.
[0029]
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. Each engine is sequentially injected and ignited at a predetermined timing, whereby the engine is automatically restarted.
[0030]
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.
[0031]
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.
[0032]
The engine control operation executed by the engine control apparatus configured as described above will be described based on the flowcharts shown in FIGS. 4 and 5. 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 an automatic engine 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.
[0033]
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).
[0034]
When it is determined YES in step S3 and it is confirmed that the engine automatic stop condition is satisfied, the opening degree of the throttle valve 12 is set to a preset reference opening degree Z, and correspondingly, After executing the control to increase the fuel injection amount to temporarily increase the engine speed (step S5), the fuel cut speed H to be described later and the target opening (target throttle opening) G of the throttle valve 12 thereafter. The setting control is executed (step S6). The reference opening Z of the throttle valve 12 prevents noise due to a sudden increase in the engine speed when the engine is automatically stopped, and the stop time due to a slow increase in the engine speed. Is determined based on experiments and the like conducted in advance as a value that can prevent unnecessarily long.
[0035]
Next, it is determined whether or not the engine speed N has reached the fuel cut speed H set in step S6 (step S7). When it is determined YES, normal fuel injection and ignition are stopped. While performing fuel cut control, the control which makes the opening degree of the throttle valve 12 the target throttle opening degree G set by said step S6 is performed (step S8).
[0036]
Thereafter, whether or not the engine speed N has reached a reference speed R set based on an experiment or the like conducted in advance to identify a cylinder that will be in the expansion stroke and a cylinder that will be in the compression stroke when the engine is automatically stopped. When a determination is made (step S9) and YES is determined, a cylinder that is in an expansion stroke and a compression stroke when the engine is automatically stopped is determined, and a cylinder and a compression stroke that are in an expansion stroke when the engine is automatically stopped Immediately before stopping, the fuel for restarting is injected at a predetermined timing into the cylinder to be executed (step S10).
[0037]
For example, as shown in FIG. 6 and FIG. 7, there are 4 cylinders having a first cylinder to a fourth cylinder so that 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.
[0038]
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.
[0039]
After performing the fuel injections F1 and F2 immediately before stopping the engine, it is determined whether or not the engine speed N has become 0 (step S11), and it is determined as YES and the engine is in an automatic stop state. At the confirmed time t3, the measurement of the stop duration T is started, and the throttle valve 12 is fully closed by setting the throttle opening to 0 (step S12).
[0040]
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 as 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 that becomes the expansion stroke and the compression stroke that becomes the expansion stroke when stopping. The air-fuel mixture generated by performing the fuel injections F1 and F2 on the three cylinders is simultaneously ignited (step S17), and the measurement value of the stop duration T is reset (step S18), and then the process returns.
[0041]
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.
[0042]
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).
[0043]
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).
[0044]
Next, a specific example of control for setting the fuel cut speed H and the subsequent target throttle opening degree G executed in step S6 will be described based on the flowchart shown in FIG. 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.
[0045]
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).
[0046]
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 by restricting the charging efficiency of the intake air to be equal to or lower than a preset upper limit value Ba when the engine is automatically stopped, thereby injecting immediately before the engine is stopped. This is to prevent the restart fuel from being compressed and ignited before the engine is stopped, and to prevent the driver from feeling uncomfortable due to engine noise and vibration.
[0047]
Further, the idling cycle number F after the fuel cut and the target throttle opening G are read from a preset map and set so as to satisfy the target intake total amount D and the charging efficiency change pattern E of the intake air (step S1). S34). As shown in FIG. 9, the map for setting the idling cycle number F 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 It is set so that the greater the increase ratio (E), the smaller the idling cycle number F, and the greater the target intake total amount D, the greater the idling cycle number F. Further, as shown in FIG. 10, the target throttle opening G after the fuel cut uses the intake charging efficiency pattern E and the target intake total amount D as parameters, and the intake charging efficiency pattern (increase rate of charging efficiency) E. The throttle opening G is set to a larger value as the engine speed increases, and the target throttle opening G is set to a larger value as the target intake total amount D increases.
[0048]
Next, a fuel cut rotational speed H that satisfies the above-mentioned idling cycle number F after the fuel cut, that is, an engine rotational speed at which the fuel cut is executed when the engine is automatically stopped is read from the map shown in FIG. S35). This map is set so that the number of idling cycles after the fuel cut is a parameter, and as the value of the idling cycle number F is larger, the fuel cut number of revolutions H is larger.
[0049]
In the vehicle control device provided with the automatic stop control means 44 for automatically stopping the engine when a preset engine automatic stop condition is satisfied in the engine idle operation state as described above, at least when the engine is automatically stopped The fuel injection means comprising a fuel injection valve 8 that injects fuel immediately before the engine is stopped to the cylinder that is in the expansion stroke, and the restart condition that is set in advance after the engine is automatically stopped, Ignition control means 43 for controlling the air-fuel mixture generated by fuel injection to ignite and restart the engine, throttle valve control means 41 for temporarily increasing the engine speed when the automatic stop condition is satisfied, and fuel A rotation speed increase means comprising an injection control means 42, and the fuel immediately before the stop after the rotation speed increase control is completed. Since configured to perform shot an, it is possible to prevent the hot surface ignition of the compressed self-ignition and the fuel-air mixture that is generated by injecting fuel into the cylinder just before the stop of the engine effectively.
[0050]
That is, as shown in FIG. 12, at the time ta when the engine automatic stop condition is satisfied, the throttle valve 12 is opened so that the opening degree of the throttle valve 12 becomes a preset reference opening degree Z. Since the intake air flow to be introduced is increased and the fuel injection amount is increased to keep the air-fuel ratio constant correspondingly, the engine speed N is temporarily increased, and thereafter The idling cycle number F increases from the time point tb when the engine speed N becomes the fuel cut speed H and the fuel cut is performed to the time point t3 when the engine is stopped. During this time, the cylinder temperature is sufficiently high. Will be reduced. 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. The engine can be restarted quickly and properly in accordance with the combustion energy obtained by igniting the fuel and the driving force applied from the restart motor 20 to the engine crankshaft 5.
[0051]
Further, in the above embodiment, as shown in FIG. 10, the target intake total amount that changes the target throttle opening G after the fuel cut according to the value related to the in-cylinder temperature such as the engine coolant temperature or the lubricating oil temperature. The target throttle opening G is changed when the target intake total amount D is large and the change rate of the intake charging efficiency is large due to a high in-cylinder temperature. Is set to a large value, so that a large amount of intake air is introduced into each cylinder after the fuel cut to effectively reduce the in-cylinder temperature, thereby reliably preventing the compression self-ignition of the air-fuel mixture. it can.
[0052]
In particular, as shown in the embodiment, when the intake charging efficiency pattern E is set so that the cylinder pressure after the fuel cut is equal to or less 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 more effectively prevented.
[0053]
In the above embodiment, the example in which the throttle opening is maintained at the constant value G from the fuel cut time tb to the time t3 when the engine is stopped has been described. However, as shown in FIG. After the opening degree of the throttle valve 12 is temporarily increased at the time tb when the fuel cut is performed, the throttle valve 12 may be shifted to a closed state before the fuel injection immediately before the stop is performed.
[0054]
That is, as shown in FIGS. 13 and 14, the charging efficiency pattern of intake air so that the cylinder pressure at the time point tc when the compression top dead center is reached after the fuel cut is equal to or lower than the allowable compression pressure B obtained in step S31. After E is set (step S33), the idling cycle number F after the fuel cut, the target throttle opening G, and the target throttle opening so as to satisfy the target intake total amount D and the charging efficiency pattern E of the intake air are satisfied. The G holding time Y is read and set from a preset map (step S34a). Specifically, the intake amount corresponding to the target intake total amount D is supplied into the cylinder by temporarily increasing the opening degree of the throttle valve 12 from the time tb when the fuel cut is performed to automatically stop the engine. In addition, the target throttle opening is set so that the intake charging efficiency at the time point tc when the cylinder in which the fuel injections F1 and F2 have been performed immediately before the engine is stopped becomes the compression top dead center is equal to or less than the preset upper limit value Ba. The degree G and the holding time Y of the target throttle opening G are set.
[0055]
As described above, at the time tb when the fuel injection to each cylinder is stopped when the automatic stop condition is satisfied, the opening degree of the throttle valve 12 is temporarily increased, and the fuel injection F1, immediately before the stop is stopped after the throttle valve 12 is closed. In the case where the engine is configured to perform F2, after the normal fuel injection is stopped and the fuel cut is performed in order to automatically stop the engine, the opening of the throttle valve 12 is temporarily increased to generate a large amount of intake air. Introducing into each cylinder has the advantage that the in-cylinder temperature can be effectively lowered and the time required for the engine to be stopped can be shortened as much as possible.
[0056]
Furthermore, as shown in the above embodiment, when the restart motor control means 45 for adjusting the driving torque of the restart motor 20 according to the stop duration T from the engine stop time to the restart time t4 is provided. The engine can be quickly and properly restarted according to the combustion energy obtained by igniting the air-fuel mixture and the driving force applied to the engine crankshaft 5 from the restart motor 20. There are advantages.
[0057]
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.
[0058]
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.
[0059]
It is determined whether or not the engine stop duration T is within a preset reference time. If it is confirmed that the engine stop duration T is within the reference time, the longer the stop duration T, the longer the restart motor. When the drive torque of 20 is set to a small value and the engine stop duration T exceeds a preset reference time, the drive torque of the restart motor 20 is set to a larger value as the stop duration T is longer. You may comprise as follows.
[0060]
According to the above configuration, since the engine stop duration T is long within the preset reference time, the fuel injected just before the engine stop is sufficiently vaporized and atomized because the stop duration T is long. When the output torque due to the combustion of the air-fuel mixture is sufficiently obtained, the engine is properly controlled while suppressing unnecessary power consumption by setting the driving torque of the restart motor 20 to a small value. Can be restarted. On the other hand, when the engine stop continuation time T exceeds a preset reference time, the output torque due to combustion of the air-fuel mixture decreases due to leakage of the air-fuel mixture from the cylinder and a decrease in the temperature in the cylinder. Since there is a tendency, the restart caused by the decrease in the output torque due to the combustion of the air-fuel mixture by setting the driving torque of the restart motor 20 to a large value corresponding to the increase in the stop duration T The engine can be restarted reliably.
[0061]
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.
[0062]
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.
[0063]
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.
[0064]
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. Moreover, 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.
[0065]
【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. The fuel injection means for injecting fuel to the cylinder that is at least in the expansion stroke at the time of the stop, and the fuel injection immediately before the stop when the preset restart condition is satisfied after the engine is automatically stopped. Ignition control means for controlling the generated air-fuel mixture to be ignited and restarting the engine, and rotation speed increasing means for temporarily increasing the engine speed when the automatic stop condition is satisfied. Since the fuel injection immediately before the stop is performed after the lift control is finished, the fuel injection is performed immediately before the engine is stopped. The generated air-fuel mixture or compression self-ignition, from or to ignite hot surface effectively prevented, there is an advantage that it is possible to properly restart the engine 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 the second half of the control operation of the control device.
FIG. 6 is a time chart showing a control operation of the control device.
FIG. 7 is a time chart showing a change state of the engine speed.
FIG. 8 is a flowchart showing a setting control operation of a fuel cut speed and a target throttle opening.
FIG. 9 is a graph showing an example of a map for setting an idling cycle of an engine.
FIG. 10 is a graph showing an example of a map for setting a target throttle opening.
FIG. 11 is a graph showing an example of a map for setting a fuel cut speed.
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 a control operation for setting a fuel cut speed, a target throttle opening, and an opening time.
[Explanation of symbols]
5 Crankshaft (output shaft)
8 Fuel injection valve (fuel injection means)
12 Throttle valve
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

Claims (4)

In a vehicle control device having 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, a cylinder that is at least in an expansion stroke when the engine is automatically stopped In contrast, the fuel injection means for injecting fuel immediately before the engine is stopped and the air-fuel mixture generated by the fuel injection immediately before the stop are ignited when a preset restart condition is established after the engine is automatically stopped. Ignition control means for controlling the engine to restart, and rotation speed increasing means for temporarily increasing the engine speed when the automatic stop condition is satisfied. A vehicle control apparatus that performs fuel injection immediately before stopping. 2. The vehicle control device according to claim 1, further comprising throttle valve control means for opening the throttle valve for a predetermined period after temporarily increasing the engine speed when the automatic stop condition is satisfied. . 3. The vehicle according to claim 2, further comprising an in-cylinder temperature detecting means for detecting a value related to an in-cylinder temperature of the engine, wherein the opening of the throttle valve is set to a larger value as the in-cylinder temperature of the engine is higher. Control device. The throttle valve opening is temporarily increased after fuel injection to each cylinder is stopped when the automatic stop condition is satisfied, and the throttle valve is closed before fuel injection immediately before the stop is performed. Item 4. The vehicle control device according to Item 1.

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