JP2006183467A - Control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize power consumption by motor assist while securing a required motor assist quantity Ta. <P>SOLUTION: The control device is equipped with a re-acceleration request detecting means for detecting a re-acceleration request by a driver which is issued before the engine is stopped after the automatic stop control of the engine has started. The control means determines a necessary and sufficient motor assist quantity for the engine on the basis of a crank angle of the engine detected at detection of the re-acceleration request. The drive motor is controlled so as to drive an output shaft of the engine by a torque corresponding to the determined motor assist quantity Ta. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle control device, and more particularly to a vehicle control device configured to restart an engine when a restart condition is satisfied after the engine is stopped.

In recent years, to reduce fuel consumption and reduce CO ₂ emissions, the engine is automatically stopped temporarily when idling, and then the engine is automatically restarted when restart conditions such as start operation are established. Automatic stop control, 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.

Therefore, as a start control device suitable for restarting the idle stop control, when the operation state of the engine satisfies the automatic stop condition during the operation of the spark ignition engine that forms the air-fuel mixture by the fuel injection of the fuel injection valve In the engine automatic stop / start control device that automatically starts the engine when the automatic start condition is satisfied, the intake air is sucked in the compression stroke when the engine is automatically stopped immediately before the engine is automatically stopped. By injecting fuel into the combustion chamber of a cylinder that is estimated to be in a state where both the valve and the exhaust valve are closed, the combustion chamber of the cylinder is brought into an air-fuel mixture state capable of spark ignition when the engine is automatically stopped. Is known (see, for example, Patent Document 1).
JP 2001-342876 A

  By the way, after the automatic stop control is started, there is a case where an acceleration request (such an acceleration request before the engine stops) is referred to as “re-acceleration request” in this specification before the engine stops. In such a case, conventionally, only a drive assist of the engine is performed by a starter motor that drives the output shaft of the engine with a constant torque. However, the torque for assisting the drive of the engine with the motor (referred to as “motor assist amount” in this specification) varies greatly depending on the phase of each cylinder for which the reacceleration request is generated. Therefore, when the engine is uniformly assisted by the starter motor when there is a reacceleration request, depending on the timing of the reacceleration request, the motor assist amount may be excessive or insufficient, and the starter motor power is wasted. Or, the necessary torque could not be obtained, the start-up time was prolonged, and there was a problem that the driver felt uncomfortable or uncomfortable.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a vehicle control device that can quickly accelerate an engine when a reacceleration request is generated.

  In order to solve the problems, the present invention provides a fuel injection means for injecting fuel into an intake port of a spark ignition engine, and an ignition means for igniting an air-fuel mixture in a cylinder generated by the fuel injected into the intake port. A drive motor that drives the output shaft of the engine, crank angle detection means that detects the crank angle of the engine, accelerator operation detection means that detects the accelerator operation of the driver, and the crank angle detection means and accelerator operation detection means If it is determined that the engine automatic stop condition is satisfied based on the detection of the engine, the engine is automatically stopped, and the engine is automatically started when the automatic start condition is satisfied. Means, an ignition means, and a control means for controlling the drive motor. This is a vehicle control device that estimates a cylinder to be expanded as a stop expansion stroke cylinder and injects restart fuel into the stop expansion stroke cylinder while igniting the stop expansion stroke cylinder when the automatically stopped engine is restarted. A re-acceleration request detecting means for detecting a re-acceleration request of a driver that has occurred between the start of the automatic engine stop control and the stop of the engine, and the control means is configured to detect the re-acceleration request. A motor assist amount necessary and sufficient for the engine is determined based on the detected crank angle of the engine, and the drive motor is controlled to drive the output shaft of the engine with a torque corresponding to the determined motor assist amount. This is a vehicle control device. In this aspect, when the automatic stop condition is satisfied after the vehicle starts running, the stop expansion stroke cylinder that becomes the expansion stroke when the engine is stopped immediately after the automatic stop control is started and immediately before the engine is stopped. Restart fuel is injected into the intake port. Furthermore, a re-acceleration request detection means is provided for detecting a re-acceleration request issued by the driver between the start of the automatic engine stop control and the stop of the engine, and the engine crank angle is detected when the re-acceleration request is detected. Then, a motor assist amount necessary and sufficient for the engine is determined according to the detected crank angle of the engine, and the drive motor is selected to drive the engine output shaft with a torque corresponding to the determined motor assist amount. Therefore, the expansion stroke cylinder at the time of stop can be quickly moved to the compression top dead center with a necessary and sufficient torque. Next, by igniting the air-fuel mixture generated in the expansion stroke cylinder at the time of stop, the air-fuel mixture generated in the expansion stroke cylinder at the time of stop can be burned and shifted to the expansion stroke. Re-acceleration operation can be performed. In addition, in the present invention, the engine is assisted based on the motor assist amount necessary and sufficient for the crank angle of the engine detected at the time of re-acceleration request, so that the power consumption can be optimized.

  In a preferred aspect, when the stop expansion stroke cylinder detects a reacceleration request when the stop expansion stroke cylinder is in a region before the first half of the exhaust stroke from the time of fuel injection for restart, the control expansion means exhausts the stop expansion stroke cylinder. The motor assist amount is made smaller than when a re-acceleration request is detected when the vehicle is in the first half of the intake stroke beyond the first half of the stroke. In this aspect, when the stop-time expansion stroke cylinder is in the region before the first half of the exhaust stroke from the time of fuel injection for restart, the engine is restarted with a smaller motor assist amount than when the first half of the exhaust stroke is exceeded and the first half of the intake stroke. Since the acceleration can be accelerated, the motor assist amount is made smaller than that when the re-acceleration request is detected when the stop-time expansion stroke cylinder is in the first half of the intake stroke beyond the first half of the exhaust stroke. Thereby, the power consumption is also reduced.

  In a preferred aspect, the control means detects a re-acceleration request when the stop-time expansion stroke cylinder is in the region of the first half of the intake stroke beyond the first half of the exhaust stroke. If it is less than the above, the motor assist amount is made smaller than when the rotational speed is equal to or higher than the set rotational speed. In this aspect, even if the stop expansion stroke cylinder when the reacceleration request is detected has the same phase, if the engine speed is less than a certain value, the required motor assist amount varies slightly. In view of this, the set rotational speed is determined by experiment or the like, and in a state where the rotational speed is less than the set rotational speed, the motor assist amount calculated by the control means is reduced to save the power consumption of the motor.

  In a preferred aspect, when the re-acceleration request is detected when the stop expansion stroke cylinder exceeds the final top dead center, the control means increases the motor assist amount more than when the final top dead center is not reached. It is to set. In this aspect, when the re-acceleration request is detected when the expansion stroke cylinder at the stop time exceeds the final top dead center, the re-acceleration request is detected in this region in view of the fact that the necessary motor assist amount increases. In such a case, the motor assist amount is set larger than that in other regions so that the engine can be started with sufficient torque.

  In a preferred aspect, the drive motor includes a first motor that drives the output shaft of the engine when the engine is started, and a second drive motor that drives the output shaft of the engine when the engine is restarted. . In this aspect, motor assist control according to the driving state can be realized according to the characteristics of a plurality of different types of motors.

  In a preferred aspect, the second drive motor is supplied with power from a battery different from the first drive motor, and detects the battery capacity of the second drive motor and inputs it to the control means. Means for calculating the maximum torque of the second drive motor from the detected battery capacity, and if this maximum torque is less than the motor assist amount, the control means controls the second drive motor at the maximum torque. In addition to driving, the first drive motor is driven to compensate for the shortage of the motor assist amount. In this aspect, when the necessary motor assist amount exceeds the maximum torque of the second drive motor, it is possible to prevent the battery of the second drive motor from running out and to secure the necessary motor assist amount. Become.

  As described above, according to the present invention, the engine crank angle is detected when the re-acceleration request is detected, and the motor assist amount necessary and sufficient for the engine is determined according to the detected engine crank angle. Since the drive motor is controlled to drive the output shaft of the engine with a torque according to the motor assist amount, the necessary motor assist amount can be secured and the power consumption by the motor assist is optimized. It has a remarkable effect that

  1 and 2 show a schematic configuration of an engine 1 according to an embodiment of the present invention. In these drawings, the engine 1 is provided with a plurality of cylinders 2. Each cylinder 2 is fitted with a piston 3 to form a combustion chamber 4 thereabove. The piston 3 is connected to the crankshaft 5 via a connecting rod (not shown).

  The combustion chamber 4 of the cylinder 2 is equipped with a spark plug 13 at the top, and an intake port 6 and an exhaust port 7 are opened. A fuel injection valve 8 is provided in the intake port 6. 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.

  The intake port 6 is provided with an intake valve 6a, and the exhaust port 7 is provided with an exhaust valve 7b. 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 valve 6a and the exhaust valve 7a of each cylinder 2 are set so that each cylinder 2 performs a combustion cycle with a predetermined phase difference.

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

  As shown in FIG. 2, the crankshaft 5 is provided with a transmission 16 that changes the rotation of the engine 1 and transmits it to the wheels 15 at one end thereof, and a restart device for the engine 1 at the other end. It 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. Further, a starter motor 25 that is fed by a power feeding system different from the battery 18 is connected to the transmission 16 via a gear mechanism 26, and is driven by the starter motor 25 during cold start. It has become so. In the illustrated embodiment, the restart motor 20 and the starter motor 25 constitute a drive motor, the starter motor 25 is a specific example of the first drive motor, and the restart motor 20 is a second drive. This is a specific example of a motor. In general, the starter motor 25 employs a motor whose torque cannot be changed. Therefore, in the motor assist control described later, the restart motor 20 capable of changing the torque is preferentially used.

  Then, when the engine 1 is restarted, the restart motor 20 is activated to drive the crankshaft 5 in response to a control signal output from the ECU (engine control unit) 30 described below. The restart motor 20 is provided with a rotation angle sensor 22 that detects the rotation angle.

  FIG. 3 is a block diagram of a control device according to an embodiment of the present invention.

  Referring to FIG. 3, ECU 30 is a unit configured by a CPU, a memory, an input / output device, and the like. The ECU 30 includes an accelerator sensor 32 that detects the depression state of the accelerator pedal, a shift position sensor 33 that detects the operation position of the shift lever, and an ignition switch that is turned ON / OFF according to the operation of the ignition key by the driver. 34, the brake switch 35 for detecting the depression state of the brake pedal, and the battery remaining amount sensor 36 for detecting the remaining amount of the battery according to the voltage of the battery 18 are input. ing.

  Further, the ECU 30 includes a crank angle sensor 14 that detects the engine speed N and the crank angle CA, a rotation angle sensor 22 that detects the rotation angle of the restart motor 20, and the coolant temperature or lubricating oil temperature of the engine 1. Based on the engine temperature sensor 37 for detecting the in-cylinder temperature of the engine 1, the intake air temperature sensor 38 for detecting the intake air temperature, the air flow sensor 39 for detecting the intake air amount, and the intake pipe negative for detecting the negative pressure in the intake pipe. Detection signals respectively output from the pressure sensor 40 are input.

  The ECU 30 is connected with an actuator 12a of the throttle valve 12, a fuel injection valve 8 as a fuel injection means, a spark plug 13 as an ignition means, an inverter 19, and a starter motor 25 as control elements. While controlling these control elements during operation, it is determined whether or not the automatic stop condition is satisfied, and when the automatic stop condition is satisfied, the control element is controlled based on the input from the input element so that the engine 1 automatically stops. The control means for controlling is functionally configured.

  FIG. 4 is a time chart during the automatic stop control of the engine 1, and FIG. 5 is a time chart showing a change state of the engine speed.

  Referring to FIGS. 4 and 5, in the automatic stop control by ECU 30, ECU 30 establishes an automatic stop condition for engine 1 in accordance with output signals from shift position sensor 33, brake switch 35, battery remaining amount sensor 36, and the like. At a timing when it is confirmed that the automatic stop condition is satisfied, a step of stabilizing the engine speed N at a value higher than the normal idle speed is first executed. For example, in an engine in which the normal idle speed is set to 650 rpm (the automatic transmission is in the drive range), the above value is set to about 810 rpm (the automatic transmission is in the neutral range).

  Next, the fuel injection for driving is stopped at the timing when the engine speed N is stabilized (hereinafter referred to as “driving fuel for driving”), and the engine speed N is set based on an experiment conducted in advance from this timing. The reference rotational speed R (for example, 260 rpm) is set to be lowered. For this control, the memory of the ECU 30 stores a reference rotational speed R set based on an experiment or the like, and the cylinder in the expansion stroke when the engine rotational speed N becomes equal to the reference rotational speed R. 2 is specified as the expansion stroke cylinder at the time of stop (in the illustrated example, the first cylinder (# 1)). For example, the first to fourth cylinders (# 1 to # 4) are provided, and the first cylinder (# 1), the third cylinder (# 3), the fourth cylinder (# 4), and the second cylinder (# 2). In the four-cylinder four-cycle engine configured to perform combustion in the order of (), it is assumed by experiments that the engine 1 is stopped after about two rotations after the rotation speed N reaches 500 rpm. In this case, 500 rpm is set as the reference rotation speed R, and the cylinder in the expansion stroke at the time t0 when the rotation speed is reached is specified as the expansion stroke cylinder at the time of stop. In the illustrated example, the ECU 30 performs the intake of the stop expansion stroke cylinder after time t1 when the crank angle CA of the stop expansion stroke cylinder reaches 540 ° (ATD-540 deg) before the compression top dead center TDC. Fuel is injected into the port, and after the time t2 when the crank angle CA reaches 360 ° (ATD-360 deg), the fuel to the intake port 6 of the cylinder that becomes the compression stroke at the time of stop (hereinafter referred to as the compression stroke cylinder at the time of stop) (Hereinafter referred to as “restart fuel”). This restart fuel is for contributing to restart of the engine 1 by being burned when the restart request of the engine 1 is made after the engine is stopped.

  Note that the cylinder that is in the expansion stroke when the engine 1 is stopped is determined by determining the cylinder that is 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 configuration specified, the rotational energy A is calculated from the rotational speed of the crankshaft 5 when the engine rotational speed N reaches a predetermined value, and this rotational energy A and one stroke of each cylinder (crank Based on the loss energy B lost during the rotation of the shaft 5 by 180 °, the rotation amount from the time t0 until the engine 1 stops may be obtained by calculation. The loss energy B is obtained by adding the pumping loss of the engine 1, the mechanical resistance of the rotating part, and the lost due to compression leakage of each cylinder.

  The restart fuel injection amount is adjusted according to the battery remaining amount detected by the battery remaining amount sensor 36. When the remaining battery amount is low, the fuel injection amount is set to a smaller value than when the battery remaining amount is large. Is done.

  Further, the ECU 30 determines whether or not the restart condition is satisfied according to the output signal of each sensor when the engine 1 is in the automatic stop state, and when it is confirmed that the restart condition is satisfied, the restart motor 20 Is operated, and the fuel-air mixture generated by fuel being injected into the cylinder immediately before the engine 1 is stopped is ignited, and when the engine 1 is restarted, fuel is sequentially injected into each cylinder in the intake stroke and the exhaust stroke. The engine 1 is automatically restarted by igniting at a predetermined timing.

  Further, when the restart control of the engine 1 is executed, the stop duration from the stop time t3 of the engine 1 to the restart time t4 is measured, and the driving torque of the restart motor 20 is determined based on the stop duration. It is configured to be adjusted. That is, the time until the restart condition is satisfied after the engine 1 is automatically stopped by the timer provided in the ECU 30 is measured as the stop duration, and when this stop duration is long, In comparison, the driving torque of the restart motor 20 is set to a small value.

  Further, when it is detected that the ignition switch 34 is turned off by the driver while the engine 1 is automatically stopped, the air-fuel mixture generated by injecting restart fuel is ignited at a predetermined timing. The control to perform is performed.

  On the other hand, in the present embodiment, when there is a request for re-acceleration of the engine 1 even during the automatic stop control of the engine 1, the restart motor 20 and the starter motor 25 are selectively used under the conditions shown in the control flow described later. It is configured to drive to. The engine reacceleration request can be detected, for example, by detecting that the driver has depressed the accelerator pedal after the automatic stop control.

  FIG. 6 is a timing chart showing a motor assist amount for driving the drive motor.

  Referring to the figure, the characteristic of motor assist amount Ta when the driver requests re-acceleration after the automatic stop control starts and before the stop is input to the memory of ECU 30. As a result of earnest research by the inventors, it has been found that the required motor assist amount Ta for the reacceleration changes according to the crank angle of the engine at the time of the reacceleration request. The motor assist amount Ta is previously determined for each phase by experiments or the like, and a control map based on the motor assist amount Ta is stored in the memory of the ECU 30.

  The example of FIG. 6 shows an example in which the first cylinder (# 1) becomes the stop expansion stroke cylinder after the automatic stop control is started, and motor assist is performed according to the phase of the stop expansion stroke cylinder. The amount Ta is set.

  In the illustrated example, when the re-acceleration request is detected when the first cylinder (# 1) is in the region D1 before the first half of the exhaust stroke from the time of fuel injection for restart, the first cylinder (# 1) is exhausted. The motor assist amount Ta is set to be smaller than when the re-acceleration request is detected when it is in the region D2 in the first half of the intake stroke beyond the first half of the stroke.

  When in the region D1, the engine can be re-accelerated with a smaller motor assist amount than when in the region D2, so there is a request for re-acceleration when the first cylinder (# 1) is in the region D1. In this case, the motor assist amount is made smaller and the power consumption is also made smaller than when the re-acceleration request is detected when in the region D2.

  Further, in the present embodiment, when the re-acceleration request is detected when the first cylinder (# 1) is in the region D2 in the first half of the intake stroke beyond the first half of the exhaust stroke, the engine speed N is set at a preset rotation. When the number is less than the number, the motor assist amount is set to be smaller than when the rotational speed is equal to or higher than the set rotational speed. That is, when the engine speed is less than a certain value when the first cylinder (# 1) is present in the region D2, the set engine speed is determined by experiment or the like in view of the fact that the required motor assist amount fluctuates small. In a state where the determined rotational speed is not satisfied, the motor assist amount Ta calculated by the ECU 30 is reduced to reduce the power consumption of the motor.

  In the present embodiment, when the re-acceleration request is detected when the first cylinder (# 1) exceeds the final top dead center (crank angle CA = 0 °), the final top dead center is not reached. The motor assist amount Ta is set larger than the time. That is, when the re-acceleration request is detected when the first cylinder (# 1) exceeds the final top dead center, the re-acceleration request is detected in this region in view of the fact that the required motor assist amount increases. In such a case, the motor assist amount is set larger than that in other regions so that the engine can be started with sufficient torque.

  By the way, in selectively controlling the restart motor 20 and the starter motor 25 based on the motor assist amount Ta, the ECU 30 determines the restart motor 20 based on the battery remaining amount detected by the battery remaining amount sensor 36. The maximum torque Tmax is calculated. If the calculated motor assist amount Ta exceeds the maximum torque Tmax, the starter motor 25 is driven to compensate for the shortage, and motor assist by both the motors 20 and 25 is realized. It has become.

  Next, automatic stop control in the present embodiment will be described with reference to FIG.

  FIG. 7 is a flowchart of automatic stop control in the present embodiment.

  Referring to FIG. 7, in the present embodiment, first, ECU 30 reads detection signals output from sensors and switches as input elements (step S1), and whether or not an automatic stop condition for engine 1 is satisfied. Is determined (step S2). Specifically, in a state in which a predetermined engine speed is detected, 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 first reference value set in advance. When it is confirmed, it is determined that the automatic stop condition of the engine 1 is satisfied, and when even one of the above requirements is not satisfied, it is determined that the automatic stop condition is not satisfied. ing.

  When the automatic stop condition of the engine 1 is not satisfied, the ECU 30 executes normal fuel injection control and ignition control according to the engine speed and the intake air amount (step S3).

  On the other hand, when the automatic stop condition of the engine 1 is satisfied, the ECU 30 executes the fuel cut for operation from the fuel injection valve 8 and stops ignition of the air-fuel mixture by the spark plug 13 in order to automatically stop the engine 1. (Step S4).

  Next, the ECU 30 calculates the position at which each cylinder stops from the crank angle sensor 14 (step S5). Thereafter, it is determined whether or not there is a reacceleration request (step S6), and if there is a reacceleration request, the process proceeds to a reacceleration request control subroutine (step S20), which will be described in detail later. After the cylinder (first cylinder (# 1)) has passed the reference rotational speed R, fuel is injected at the timing when the first half of the expansion stroke is reached (step S7; see F1 in FIGS. 4 to 6).

  Thereafter, it is determined whether or not there is a reacceleration request (step S8), and if there is a reacceleration request, the process proceeds to a reacceleration request control subroutine in step S20, and if there is no reacceleration request, the stop compression stroke cylinder (third cylinder ( In step # 9), fuel is injected at the timing when the first half of the exhaust stroke is reached (step S9; see F2 in FIGS. 4 and 5).

  Thereafter, it is determined whether there is a reacceleration request (step S10). If there is a reacceleration request, the process proceeds to a reacceleration request control subroutine in step S20. If there is no reacceleration request, the engine stop control subroutine (step S30) is executed. Then, the process ends.

  Next, the engine re-acceleration request control subroutine (step S20) will be described. FIG. 8 is a flowchart of an engine reacceleration request control subroutine.

  Referring to FIG. 8, when there is an engine reacceleration request, ECU 30 detects crank angle CA at the time of the reacceleration request (step S201), and from the control map based on the timing chart of FIG. Is determined (step S202). Based on the motor assist amount Ta, the restart motor 20 is first driven (step S203). The starter motor 25 drives the crankshaft 5 of the engine 1 with a constant torque, whereas the restart motor 20 can drive the crankshaft 5 with a variable torque, so that the motor assist amount Ta is relatively low. If it is small, the power consumption of the battery 18 can be saved as much as possible and the engine 1 can be assisted and controlled.

  Next, the ECU 30 calculates the maximum torque Tmax of the restart motor 20 based on the battery remaining amount detected by the battery remaining amount sensor 36 (step S204). Next, the calculated maximum torque Tmax is compared with the motor assist amount Ta to determine whether the motor assist amount Ta exceeds the maximum torque Tmax of the restart motor 20 (step S205). If the motor assist amount Ta exceeds the maximum torque Tmax, the ECU 30 drives the starter motor 25 in order to compensate for the shortage (step S206). As a result, even when a large motor assist amount Ta is required, it is possible to obtain a motor assist amount Ta without excess or deficiency using both the motors 20 and 25.

  After the starter motor 25 is driven, or when it is determined in step S205 that the motor assist amount Ta is equal to or less than the maximum torque Tmax of the restart motor 20, the ECU 30 determines that the restart fuel is the stop-time expansion stroke cylinder (the first cylinder). It is determined whether or not the fuel is injected into the intake port 6 of one cylinder (# 1) (step S207). If the restart fuel is not injected into the intake port 6 of the expansion stroke cylinder at the time of stop, the ECU 30 The fuel is injected into the cylinder that has reached the second half of the exhaust stroke and the cylinder that has reached the first half of the intake stroke (step S208). Thereafter, ignition is performed when these cylinders reach compression top dead center (steps S209 and 210), and the process proceeds to step S214.

  On the other hand, if injection is performed in step S207, ignition is performed when the expansion stroke cylinder at the time of stop (first cylinder (# 1)) reaches compression top dead center (step S211). Next, the ECU 30 determines whether or not fuel is being injected into the stop-time compression stroke cylinder (step S212). If the fuel has not been injected, the ECU 30 proceeds to step S214 as it is, while temporarily injecting fuel. If so, ignition is performed when the compression stroke cylinder at the time of compression reaches the top dead center (step S213).

  In step S214, it is determined whether or not the engine speed N has reached a predetermined assist end speed Nstd (for example, 500 rpm). If a speed equal to or greater than the assist end speed Nstd is detected, restart is performed. The motor 20 is stopped (step S215), and the reacceleration control is terminated.

  FIG. 9 is a flowchart of the engine stop control subroutine (step S30) in FIG.

  Referring to FIG. 9, in the engine stop control subroutine, motor assist control to be described later is executed (step S300), it is determined whether engine speed N has become 0 (step S301), and YES is determined. Then, at the time t3 (see FIG. 4) when it is confirmed that the engine is in the automatic stop state, measurement of the stop duration T is started (step S302). Next, when it is detected that the engine speed N is 0, it is determined whether or not the driver has performed an OFF operation of the ignition switch 34 (step S303).

  If it is determined NO in step S303 and it is confirmed that the ignition switch 34 is not turned off, the driving torque of the restart motor 20 is set by reading it from the table (step S304). 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 t4 (see FIG. 4) when the restart condition is satisfied, and a predetermined amount of air-fuel mixture is generated by injecting fuel into the two cylinders immediately before the engine is stopped. The engine is restarted by performing ignition SP1 and SP2 at the timing (step S305).

  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 S306), and these cylinders become compression top dead centers. After the ignition of the air-fuel mixture SP3 and SP4 is performed sequentially (step S307), the measured value of the stop duration T is reset to 0 (step S308).

  On the other hand, if it is determined YES in step S303 and it is confirmed that the driver has turned off the ignition switch 34 with the intention of stopping, the first cylinder (# 1) that is in the expansion stroke at the time of stoppage. Further, ignition is performed on the air-fuel mixture generated by performing the fuel injections F1 and F2 on the third cylinder (# 3) that is in the compression stroke (step S309), and the process proceeds to step S308 and returns.

  Next, the motor assist control executed in step S300 will be described based on FIG. 10 and FIG. FIG. 10 is a flowchart showing the motor assist control operation, and FIG. 11 is a time chart showing the motor assist control operation.

  Referring to FIGS. 10 and 11, when the control operation is started, the actual engine at the time ta, tb at which the crank angle CA of the first cylinder determined to be in the expansion stroke when the engine 1 is stopped becomes a predetermined value. A rotational speed deviation δ between the rotational speed N and a target rotational speed L obtained in advance by experiment is calculated (step S311), and the driving torque of the restart motor 20 corresponding to the rotational speed deviation δ, that is, assist at the time of stoppage is calculated. The force is obtained (step S312).

  For example, as shown in FIG. 11, the engine speed N at the time ta when the crank angle CA of the first cylinder becomes 180 ° before the compression top dead center TDC is equal to or less than the target speed L, and at the time ta. When it is confirmed that the rotational speed deviation δ1 is a negative value, in order to bring the engine rotational speed N close to the target rotational speed L, a positive drive torque corresponding to the rotational speed deviation δ1 is set. Further, the engine speed N at the time tb when the crank angle CA of the first cylinder becomes the compression top dead center TDC is equal to or higher than the target speed L, and the speed deviation δ2 at the time tb is a positive value. Is confirmed, the reverse drive torque (brake torque) corresponding to the deviation is input to the crankshaft 5 so that the engine speed N is controlled to approach the target speed L.

  Then, by outputting an operation command signal to the restart motor 20 (step S313), after applying the stop assist force obtained in step S312 to the crankshaft 5, the expansion stroke occurs when the engine 1 is stopped. Based on the engine speed N when the determined crank angle CA of the first cylinder reaches the target stop position, that is, when the crank angle CA of the first cylinder reaches 120 ° after the compression top dead center TDC. The amount of reverse rotation of the engine 1 that occurs when the engine is stopped is predicted (step S314). Thereafter, by outputting an operation command signal corresponding to the reverse rotation amount to the restart motor 20, a positive drive torque corresponding to the predicted value of the reverse rotation amount is applied to the crankshaft 5 (step S315).

  That is, when the engine is stopped, in the cylinder in the compression stroke, as the piston 3 approaches the top dead center, the air in the cylinder is compressed and pressure is applied in the direction of pushing back the piston 3, thereby causing the engine 1 to reverse. When the piston 3 of the cylinder is pushed back to the bottom dead center side, the piston 3 of the cylinder in the expansion stroke moves to the top dead center side, and accordingly, the air in the cylinder is compressed and expanded by the pressure. Since a reverse rotation phenomenon occurs in which the piston 3 of the cylinder in the stroke is pushed back to the bottom dead center side, a positive drive torque corresponding to the reverse rotation amount is applied to the crankshaft 5 to set the stop position of the crankshaft 5 as a target. It is possible to accurately match the stop position.

  Note that the drive torque applied from the restart motor 20 is controlled based on the rotational speed deviation δ between the actual engine rotational speed N at a predetermined time point and the target rotational speed L obtained in advance through experiments as described above. Thus, instead of the above embodiment in which the engine 1 is stopped when the crank angle CA of the cylinder reaches the target stop position, for example, it is calculated according to the output signals of the air flow sensor 39 and the crank angle sensor 14. The crankshaft torque may be calculated at a predetermined timing based on the intake charging efficiency, and the driving torque applied by the restart motor 20 may be controlled based on this value.

  For example, as shown in FIG. 12, the expansion torque of the first cylinder is obtained based on the charging efficiency of the intake air, the compression torque of the third cylinder, the intake resistance of the fourth cylinder, the exhaust resistance of the second cylinder, and the entire engine 1 The crankshaft torque may be calculated by obtaining the mechanical resistance and subtracting these values from the expansion torque of the first cylinder. The drive torque applied by the restart motor 20 may be controlled based on the deviation between the calculated value of the crankshaft torque and a preset target shaft torque.

  Further, as shown in FIG. 13, the peak value of the crankshaft torque is read out from a preset map using the intake charging efficiency and the engine speed N as parameters, and this value and the preset target shaft torque Based on the deviation, the driving torque applied by the restart motor 20 may be controlled.

  Further, as shown in FIG. 14, the deviation between the engine speed N and the target speed L is sequentially calculated from a predetermined time point ta, or the deviation between the crankshaft torque and the target shaft torque is sequentially calculated. The engine 1 may be stopped when the crank position of the cylinder reaches the target stop position by feedback control of the drive torque applied from the restart motor 20 based on the deviation.

  In the present embodiment, an accelerator sensor 32 is provided as a reacceleration request detection means, and when the reacceleration request is detected, the crank angle CA of the engine 1 is detected by the crank angle sensor 14 as a crank angle detection means. As the drive motor, the motor assist amount Ta necessary and sufficient for the engine 1 is determined according to the crank angle CA of 1, and the crankshaft 5 of the engine 1 is driven with a torque corresponding to the determined motor assist amount Ta. Since the restart motor 20 and the starter motor 25 are selectively controlled, the expansion stroke cylinder at the time of stop can be quickly moved to the compression top dead center with a necessary and sufficient torque, Based on the necessary and sufficient motor assist amount Ta for the crank angle CA of the engine 1 detected when re-acceleration is requested. Since assist the engine 1, it is possible to optimize the consumption power.

  Moreover, in this embodiment, when the ECU 30 detects a re-acceleration request when the stop expansion stroke cylinder is in the region before the restart fuel injection and before the first half of the exhaust stroke, the ECU 30 exhausts the stop expansion stroke cylinder. The motor assist amount Ta is made smaller than when the re-acceleration request is detected when it is in the first half of the intake stroke beyond the first half of the stroke. Accordingly, when the stop expansion stroke cylinder is in the region before the first half of the exhaust stroke from the time of fuel injection for restart, the engine 1 is restarted with a smaller motor assist amount Ta than when the first half of the exhaust stroke is exceeded and the first half of the intake stroke. Since the acceleration can be performed, the motor assist amount Ta is made smaller than when the re-acceleration request is detected when the expansion stroke cylinder at the time of stop is in the first half of the intake stroke and beyond the first half of the exhaust stroke. Thereby, the power consumption is also reduced.

  Further, in the present embodiment, when the ECU 30 detects a re-acceleration request when the stop-time expansion stroke cylinder is in the region of the first half of the intake stroke beyond the first half of the exhaust stroke, the engine 1 rotation speed is set in advance. When the rotational speed is not reached, the motor assist amount Ta is made smaller than when the rotational speed is equal to or higher than the set rotational speed. As described above, in the present embodiment, even when the stop expansion stroke cylinder when the reacceleration request is detected has the same phase, if the engine rotation speed is less than a certain value, the necessary motor assist amount Ta In view of the fact that the motor speed fluctuates slightly, the set rotational speed is determined by experiment or the like, and when the rotational speed is less than the set rotational speed, the motor assist amount Ta calculated by the control means is reduced to save the motor power consumption. it can.

  Further, in the present embodiment, when the re-acceleration request is detected when the stop expansion stroke cylinder exceeds the final top dead center, the ECU 30 sets the motor assist amount Ta more than when the final top dead center is not reached. Set larger. As described above, in the present embodiment, when the re-acceleration request is detected when the stop-time expansion stroke cylinder exceeds the final top dead center, the necessary motor assist amount Ta is increased. When an acceleration request is detected, the motor assist amount Ta can be set larger than that in other areas, and the engine 1 can be started with sufficient torque.

  Further, in this embodiment, the restart motor 20 is supplied with power from a battery 18 different from the starter motor 25, and serves as a battery capacity detection unit that detects the battery capacity of the restart motor 20 and inputs the detected battery capacity to the ECU 30. The battery remaining amount sensor 36 is provided, and the ECU 30 calculates the maximum torque Tmax of the restart motor 20 from the detected battery capacity. If the maximum torque Tmax is less than the motor assist amount Ta, the ECU 30 In addition to driving with the maximum torque Tmax, the starter motor 25 is driven to compensate for the shortage of the motor assist amount Ta. As described above, in the present embodiment, when the necessary motor assist amount Ta exceeds the maximum torque Tmax of the restart motor 20, the battery of the restart motor 20 is prevented from running out and the necessary motor assist amount Ta is secured. It becomes possible to do.

  Therefore, in this embodiment, the necessary motor assist amount Ta can be ensured, and the power consumption by the motor assist can be optimized.

  The above-described embodiments are merely examples of preferred specific examples of the present invention, and the present invention is not limited to the above-described embodiments.

  FIG. 15 is a timing chart showing a motor assist amount for driving a drive motor according to another embodiment of the present invention.

  With reference to the figure, in this aspect, when a restart acceleration request is made when the restart motor 20 cannot be used for some reason, the starter motor 25 exclusively performs motor assist. Specifically, when the motor assist amount Ta is assumed as shown in the figure, a predetermined target start time is set correspondingly, and it is assumed that the target start time is exceeded when there is no motor assist. In this range, the starter motor 25 is operated to assist the engine 1 with motor assistance.

  Even in such an aspect, it is possible to realize suitable motor assist in a state where power consumption is relatively saved.

  As described above, in this embodiment, the restart motor 20 and the starter motor 25 are employed as the drive motors, and these are configured to be selectively controlled. According to the characteristics, motor assist control according to the driving state can be realized.

  The specific configuration of the apparatus of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. For example, the engine 1 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. Alternatively, instead of the above embodiment in which fuel is injected immediately before the engine 1 is stopped into the cylinders that are in the exhaust stroke, the expansion stroke, and the compression stroke when the engine 1 is stopped, the exhaust stroke and the expansion stroke are stopped when the engine 1 is stopped. You may make it inject a fuel only with respect to the cylinder which becomes.

  It goes without saying that various modifications can be made within the scope of the claims of the present invention.

1 shows a schematic configuration of an engine according to an embodiment of the present invention. 1 shows a schematic configuration of an engine according to an embodiment of the present invention. It is a block diagram of the control apparatus by embodiment of this invention. It is a time chart at the time of automatic stop control of an engine. It is a time chart which shows the change state of an engine speed. It is a timing chart which shows the motor assist amount for driving a drive motor. It is a flowchart of the automatic stop control in this embodiment. It is a flowchart of an engine reacceleration request control subroutine. It is a flowchart of the engine stop control subroutine in FIG. It is a flowchart which shows a motor assist control operation. It is a time chart which shows motor assist control operation. It is explanatory drawing which shows the specific structure of the calculating means of a crankshaft torque. It is a graph which shows an example of the map for calculating | requiring an axial torque peak value. It is a time chart which shows another example of motor assist control operation. It is a timing chart which shows the motor assist amount for driving the drive motor which concerns on another embodiment of this invention.

Explanation of symbols

1 Engine 2 Cylinder 6 Intake port 13 Spark plug 14 Crank angle sensor 16 Transmission 18 Battery 19 Inverter 20 Restart motor (second drive motor)
21 Power transmission mechanism 22 Rotation angle sensor 25 Starter motor (first drive motor)
26 Gear mechanism 32 Accelerator sensor 35 Brake switch 36 Battery level sensor CA Crank angle ECU 30
D1, D2 Region R Reference speed Ta Motor assist amount Tmax Maximum torque

Claims (6)

Fuel injection means for injecting fuel into the intake port of the spark ignition engine;
Ignition means for igniting an air-fuel mixture in a cylinder generated by fuel injected into the intake port;
A drive motor that drives the output shaft of the engine;
Crank angle detecting means for detecting the crank angle of the engine;
An accelerator operation detecting means for detecting the driver's accelerator operation;
Based on the detection of the crank angle detection means and the accelerator operation detection means, when it is determined that the engine automatic stop condition is satisfied, the engine is automatically stopped, and the engine is started when the automatic start condition is satisfied. A fuel injection means, an ignition means, and a control means for controlling the drive motor, and a cylinder that stops in an expansion stroke when stopped by starting an automatic stop control. A control device for a vehicle that injects restart fuel into the stop expansion stroke cylinder while igniting the stop expansion stroke cylinder when the automatically stopped engine is restarted,
Re-acceleration request detection means is provided for detecting a driver's re-acceleration request that has occurred between the start of the engine automatic stop control and the engine stop,
The control means determines a motor assist amount necessary and sufficient for the engine based on the crank angle of the engine detected when the reacceleration request is detected, and outputs an engine output shaft with a torque corresponding to the determined motor assist amount. A vehicle control apparatus for controlling the drive motor so as to drive the vehicle. The vehicle control device according to claim 1,
When the control means detects a re-acceleration request when the stop expansion stroke cylinder is in the region before the first half of the exhaust stroke from the time of fuel injection for restart, the stop expansion stroke cylinder exceeds the first half of the exhaust stroke. The vehicle control device is characterized in that the motor assist amount is made smaller than when a reacceleration request is detected when in the first half of the intake stroke. The vehicle control device according to claim 1 or 2,
The control means detects the reacceleration request when the stop-time expansion stroke cylinder is in the first half of the intake stroke beyond the first half of the exhaust stroke, and the engine speed is less than a preset set speed The vehicle control apparatus is characterized in that the motor assist amount is made smaller than when the rotational speed is equal to or higher than the set rotational speed. The vehicle control device according to any one of claims 1 to 3,
The control means sets a motor assist amount larger than when the final top dead center is not reached when a re-acceleration request is detected when the stop expansion stroke cylinder exceeds the final top dead center. There is provided a control device for a vehicle. The vehicle control device according to any one of claims 1 to 4,
The drive motor includes a first motor that drives the output shaft of the engine when the engine is started, and a second drive motor that drives the output shaft of the engine when the engine is restarted.
The vehicle control apparatus, wherein the control means selectively controls the first and second drive motors. The vehicle control device according to claim 5, wherein
The second drive motor is fed from a battery different from the first drive motor,
Battery capacity detection means for detecting the battery capacity of the second drive motor and inputting it to the control means;
The control means calculates the maximum torque of the second drive motor from the detected battery capacity, and when the maximum torque is less than the motor assist amount, drives the second drive motor with the maximum torque, A vehicle control device that drives the first drive motor to compensate for the shortage of the motor assist amount.

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