KR100935708B1 - Start control device and start control method for restarting engine - Google Patents

Abstract

In an engine having a variable valve mechanism for varying the valve operating angle and the valve lift amount of an intake valve, the valve operating angle and the valve lift amount of the intake valve are changed small when the engine stops automatically when the conditions of the idle stop are satisfied. Thus, the load on the valve valve mechanism at the time of restarting is reduced. In addition, when a restart request occurs, the engine is started by obtaining an initial explosion pressure by fuel injection and ignition of the cylinder stopped in the expansion stroke. In addition, after the initial intake stroke, the valve operating angle and the valve lift amount of the intake valve are increased.

Engine, auto stop, auto restart

Description

Start control device and start control method for engine restart {APPARATUS FOR AND METHOD OF CONTROLLING A STARTING OPERATION TO RESTART AN ENGINE}

The present invention relates to a start control device and a start control method for restarting an engine in which operation is stopped. More specifically, the present invention relates to a technique for restarting an engine by igniting fuel in a combustion chamber of an engine in an engine having a variable valve mechanism for varying an opening characteristic of an engine valve.

Japanese Laid-Open Patent Publication No. 2005-030236 discloses that the engine is automatically stopped when a condition for automatically stopping the engine operation is performed during idle operation of the engine, and when the restart condition is established after the engine is stopped, A vehicle control apparatus is disclosed for igniting and restarting an engine.

By the way, in case of restarting the engine without using the starter motor in the above manner, the engine is increased by increasing the allowable torque, which is the difference between the torque required to start the rotational motion of the crankshaft and the torque generated by the engine, as much as possible. Restart success rate can be increased.

Therefore, in the prior art, studies have been made to increase the engine generated torque by, for example, improving the combustion performance of the engine. However, it is difficult to stably obtain a high engine start success rate only by improving the combustion performance of the engine.

On the other hand, as a method of increasing the marginal torque, a method of lowering the torque required to start the rotational movement of the crankshaft by lowering the friction of the engine has been proposed. However, conventionally, no means have been proposed for achieving an effective reduction of engine friction, which can greatly contribute to increasing the engine restart success rate.

Accordingly, an object of the present invention is to increase the engine restarting success rate by lowering the torque required to start the rotational motion of the crankshaft by lowering engine friction in an engine having a variable valve mechanism provided to vary the opening characteristics of the engine valve. There is.

In order to achieve the above object, the present invention is a novel technical idea to forcibly lower the load applied by the variable valve mechanism when the engine is restarted by igniting the fuel in the combustion chamber of the engine when the engine operation is stopped. To provide.

Further objects and features of the present invention will be understood by the following description with reference to the accompanying drawings.

According to the present invention, in an engine having a variable valve mechanism provided for varying the opening characteristic of an engine valve, the engine restart success rate can be increased by lowering the torque required to start the rotational movement of the crankshaft by lowering engine friction. have.

1 is a block diagram showing a system structure of a vehicle engine according to an embodiment of the present invention.

In Fig. 1, the engine 101 is an internal combustion engine engine composed of a V-type six-cylinder engine having two banks of right and left, to which the present invention can be applied. By the fuel is ignited by the engine.

An electronic control throttle 104 is mounted to the suction pipe 102 of the engine 101.

Air passing through the electronic control throttle 104 is distributed to each bank and then to each cylinder of each bank.

In each cylinder, air is sucked into the combustion chamber 106 through the intake valve 105.

The gas combusted in the combustion chamber 106 of each cylinder is discharged from the combustion chamber 106 through the exhaust valve 107 and then collectively flows through each bank, and the front catalytic converters 108a and 108b installed at each bank and the rear Purification by catalytic converters 109a and 109b.

The exhaust gas flowing out of each bank after being purified by the rear catalytic converters 109a and 109b is introduced into the common exhaust passage, flows into the muffler 103, and is then discharged into the atmosphere from the muffler 103. .

The exhaust valve 107 is driven to open and close under a constant valve lift amount, a constant valve operating angle, and a constant valve timing by a cam axially supported by the exhaust camshaft 110.

On the other hand, the valve lift amount, valve operation angle, and valve timing of the intake valve 105 on each bank are variable valve lift mechanisms 112a and 112b and variable valve timing mechanisms 113a and 113b constituting variable valve mechanisms provided for each bank, respectively. Variable control.

The variable valve lift mechanisms 112a and 112b are mechanisms for continuously varying the valve lift amount and the valve operating angle of the intake valve 105.

The variable valve timing mechanisms 113a and 113b are mechanisms for continuously varying the center phase of the valve operating angle of the intake valve 105 by changing the rotational phase of the intake camshaft 3 with respect to the crankshaft.

An electronic control unit (ECU) 114 incorporating a microcomputer sets a target intake air amount and a target intake negative pressure in accordance with an operating condition of the engine, and the electronic control throttle 104 based on the set target intake air amount and a target intake negative pressure. ), The variable valve lift mechanisms 112a and 112b and the variable valve timing mechanisms 113a and 113b are controlled.

The electronic control unit 114 includes an air flow sensor 115 for detecting the intake air flow rate of the engine 101, an accelerator sensor 116 for detecting the stepped amount of the accelerator pedal, and a crank for detecting the rotation angle of the crankshaft. The angle sensor 117, the throttle sensor 118 for detecting the opening degree TVO of the electronically controlled throttle 104, the water temperature sensor 119 for detecting the coolant temperature of the engine 101, and are provided for each bank and exhausted Air-fuel ratio sensors 111a and 111b for detecting the air-fuel ratio based on the oxygen concentration in the gas, a brake switch 120 that is turned on when the foot brake of the vehicle is operated, a vehicle speed sensor 121 for detecting the vehicle speed, and the like. Signals are input from the same several sensors.

The cylinder bore of each bank cylinder is provided with a fuel injection valve 131 for directly injecting fuel into the combustion chamber 106. Moreover, the spark plug 122 is provided in the upper end part of the combustion chamber 106.

Next, the structures of the variable valve lift mechanisms 112a and 112b and the variable valve timing mechanisms 113a and 113b will be described with reference to FIGS. 2 to 4.

The engine 101 is provided with a pair of intake valves 105 and 105 in each cylinder of each bank, and is rotated by a crank shaft of the engine 101 above the intake valves 105 and 105. The intake camshaft 3 is rotatably supported along the cylinder row direction.

On the outer circumferential surface of the intake camshaft 3, rocking cams 4 which contact the valve lifter 2a of each intake valve 105 to open and close the intake valve 105 with respect to the intake camshaft 3, respectively. It is fitted so as to be relatively rotatable.

Between the intake camshaft 3 and the swing cam 4, variable valve lift mechanisms 112a and 112b for continuously changing the valve operating angle and valve lift amount of the intake valve 105 are provided.

Further, at one end of the intake camshaft 3 on each bank, the center phase of the valve operating angle of the intake valve 105 is continuously changed by changing the rotational phase of the intake camshaft 3 with respect to the crankshaft. Variable valve timing mechanisms 113a and 113b are provided.

As shown in FIGS. 2 and 3, the variable valve lift mechanisms 112a and 112b each have a circular drive cam 11 which is fixed to the intake cam shaft 3 and is fixedly installed, and the drive cam ( A ring-shaped link 12 fitted to an outer circumferential surface of the drive cam 11 so as to be relatively rotatable relative to the drive cam 11, and a control shaft 13 extending in the cylinder row direction substantially parallel to the intake cam shaft 3; A circular control cam 14 fixed to the control shaft 13 so as to be fixed and the outer peripheral surface of the control cam 14 so as to be relatively rotatable with respect to the control cam 14, and at one end thereof. Is provided with a rocker arm 15 connected to the tip of the ring-shaped link 12, and a rod-shaped link 16 connected to the other end of the rocker arm 15 and the swinging cam 4.

The control shaft 13 is driven to rotate within a predetermined angle range by an actuator 17 such as a motor, via the gear train 18.

According to the above configuration, when the intake camshaft 3 rotates in conjunction with the crankshaft, the ring-shaped link 12 almost translates while the drive cam 11 is interposed, and the rocker arm 15 is controlled. It swings around the axial center of the cam 14, and the swinging cam 4 rocked through the rod-shaped link 16, and the intake valve 105 is opened and closed.

In addition, by changing the rotation angle of the control shaft 13, the position of the shaft center of the control cam 14, which is the swing center of the rocker arm 15, is changed, and as a result, the orientation of the swing cam 4 is changed. Change.

Therefore, while making the center phase of the valve operating angle of each intake valve 105 substantially constant, the valve operating angle and the valve lift amount of the intake valve 105 are continuously changed.

Further, the valve variable valve lift mechanisms 112a and 112b each having different characteristics in which the central phase change of the valve operating angle occurs substantially simultaneously with changing the valve operating angle and the valve lift amount of the intake valve 105. Can be used.

4 shows the variable valve timing mechanisms 113a and 113b.

Each of the variable valve timing mechanisms 113a and 113b is fixed to a sprocket 25 that rotates in synchronism with the crankshaft, and to the first rotating body 21 and the bolt 22a that rotate together with the sprocket 25. A second rotary body 22 fixed to one end of the intake camshaft 3 and rotating together with the intake camshaft 3, and an inner circumferential surface of the first rotating body 21 through the helical spline 26. And a cylindrical intermediate gear 23 snapped on the outer circumferential surface of the second rotating body 22.

A drum 27 is connected to the intermediate gear 23 with a screw 28 interposed therebetween, and a torsion spring 29 is mounted between the drum 27 and the intermediate gear 23.

The intermediate gear 23 is elastically supported by the torsion spring 29 in a direction (left direction in FIG. 4) that causes the valve timing to be changed. The voltage is applied to the electromagnetic retarder 24. When applied and generates a magnetic force, it moves in the direction (right direction of FIG. 4) which advances valve timing through the movement of the drum 27 and the screw 28. As shown in FIG.

The relative phases of the rotors 21, 22 change according to the axial position of the intermediate gear 23, and thus the rotational phase of the intake camshaft 3 with respect to the crankshaft changes. The central phase of the valve operating angle changes continuously.

In one example, the actuator 17 and the electromagnetic retarder 24 configured as electric motors are controlled to be driven by a control signal transmitted from the electronic control unit 114.

The electronic control unit 114 sets the target angle of the control shaft 13 and the actuator 17 so that the actual angle of the control shaft 13 detected by the angle sensor 32 approaches the set target angle. Feedback control of the manipulated variable.

In addition, the electronic control unit 114, the crankshaft from the signal from the cam sensor 31 that outputs a signal at the reference angle position of the intake camshaft 3, and the signal from the crank angle sensor 117 The rotational phase of the intake camshaft 3 with respect to is detected, and the operation amount of the said electromagnetic retarder 24 is feedback-controlled so that this detection result may become close to a target rotational phase.

In addition, the electronic control unit 114 automatically stops the operation of the engine 101 when the automatic operation stop condition is satisfied in the idle operation state of the engine 101, and operates after automatically stopping the operation of the engine 101. It has an idle-stop-start control function which automatically restarts the engine 101 when a restart condition is established.

According to the idle stop start function of the electronic control unit 114, for example, the operation of the engine 101 is automatically stopped in a signal standby state at an intersection, thereby reducing fuel consumption and reducing exhaust emissions. do.

In restarting the operation of the engine 101 by the idle stop start function, it is required to immediately start the engine 101 in response to the driver's starting operation. For this purpose, instead of starting using the starter motor, as described later, the engine 101 is started by igniting fuel in the combustion chamber while the engine 101 is stopped.

The flowchart of FIG. 5 shows details of idle-stop-start control executed by the electronic control unit 114.

In step S201, it is determined whether a condition for automatically stopping the operation of the engine 101 is established.

At this time, if all of the following conditions (1) to (5) are satisfied, it is determined that a condition for automatically stopping the operation of the engine 101 is established.

(1) The vehicle speed is 0 km / h

(2) The engine speed (rpm) is below the reference speed

(3) Accelerator opening degree is fully closed

(4) The brake switch 120 is ON

(5) The coolant temperature is higher than the reference temperature

The automatic operation stop condition assumes that the driving of the engine 101 is automatically stopped when the vehicle is temporarily stopped due to signal wait or the like at the intersection with the engine 101 sufficiently warmed up. However, the conditions for automatic stop are not limited to the above.

If the condition of automatic stop does not hold, this routine is terminated as it is, and the operation of the engine 101 is continued.

On the other hand, when the automatic operation stop condition is satisfied, the intake air amount of the engine 101 and the opening characteristic of the intake valve 105 are controlled before the engine 101 is stopped.

First, in step S202, the electronic control throttle 104 is closed to the opening degree at which the amount of intake air required for idle operation is obtained.

In the next step S203, the variable valve lift mechanisms 112a and 112b are controlled so that the valve operating angle and the valve lift amount of the intake valve 105 are maximum, and the center phase of the valve operating angle of the intake valve 105 is maximized. Each of the variable valve timing mechanisms 113a and 113b is controlled to be late.

It should be noted at this stage that the engine 101 is changed by changing the opening characteristics of each of the intake valves 105 by the variable valve lift mechanisms 112a and 112b and the variable valve timing mechanisms 113a and 113b during normal operation. The intake negative pressure is controlled by controlling the amount of intake air in the air and changing the throttle opening degree by the electronic control throttle 104.

On the other hand, the processing of step S202 and step S203 is to change to the state in which the intake air amount and the suction negative pressure are controlled by the electronic control throttle 104. That is, the variable valve lift mechanisms 112a and 112b and the variable valve timing mechanisms 113a and 113b are controlled to have a maximum amount of intake air by the processing in step S203. However, the electronic control throttle 104 is controlled by the processing in step S202. By decreasing the opening degree of), the amount of intake air during idle operation is controlled.

In step S204, the fuel injection of the fuel injection valve 131 is stopped, and the operation of the engine 101 is stopped by stopping the ignition by the spark plug 122.

In step S205, while the engine 101 rotates by inertia, the opening degree of the electronically controlled throttle 104 whose opening degree is reduced to make the intake air amount of the engine 101 the intake air amount during idle operation is developed. Shall be.

Even when the opening degree of the electronic control throttle 104 is developed, since the fuel injection and ignition have been stopped before, the generated torque of the engine 101 does not increase.

If the opening degree of the electronic control throttle 104 is developed while the engine 101 is rotating by inertia after stopping the fuel injection and ignition, the variable valve lift mechanisms 112a and 112b and the variable valve timing mechanism 113a, Since the intake air amount 113b is controlled to be the maximum, the engine 101 inhales a lot of air.

Subsequently, a large compression work occurs in each cylinder by the engine 101 taking in a large amount of intake air, whereby one of the six cylinders can be stopped at a substantially constant piston position during the expansion stroke. It should be noted that in the cylinder which is stopped during the expansion stroke, intake air is trapped therein.

As will be described later, when the operation of the engine 101 is restarted, fuel is injected and ignited to the cylinder in which the piston movement is stopped during the expansion stroke, and thus the crankshaft starts to rotate at the explosion pressure at this time. Therefore, in order to perform the restart, it is necessary to stop one of the six cylinders in the expansion stroke.

At this time, if the load when the engine 101 rotates inertia is small, the braking force due to the compression work is weakened, and the piston stops at a relatively delayed time during the expansion stroke. Therefore, when the piston movement stops at a delayed time during the expansion stroke, the rotational force obtained by combustion in the cylinder is weakened, and the starting performance is lowered.

Therefore, the amount of intake air when the engine 101 rotates inertia is increased to stop one of the six cylinders in the advanced position as far as possible during the expansion stroke.

In step S206, it is determined from the signal of the crank angle sensor 117 whether the rotation of the engine 101 is completely stopped.

When the rotation of the engine 101 stops completely, the flow advances to step S207.

In step S207, the opening degree of the electronically controlled throttle 104 is closed to the opening degree at which the intake air amount can be obtained during idle operation in preparation for restarting the engine 101, and the intake air controlled by the variable valve lift mechanisms 112a and 112b is also controlled. The valve operating angle and the valve lift amount of the valve 105 are controlled to be a target value suitable for the automatic start of the engine, that is, the engine 101.

The target value for the automatic start is set to a value smaller than the target value at the time of start using the starter motor and is smaller than the value required for the continuation of the start of the engine 101. As a result, the load of the variable valve lift mechanisms 112a and 112 at the time of automatic starting, in other words, the load of the opening drive of the intake valve 105 can be greatly reduced.

As shown in FIG. 8, the intake stroke in which the intake valve 105 is driven to the target value for automatic start is set only to the first one cylinder, and combustion in the cylinder is the fourth of six cylinders. It is burning. By controlling the operating angle of the intake valve 105 and the valve lift amount to reach the target value for automatic start of the engine, the intake air amount of each cylinder is greatly reduced, and there is a possibility that sufficient torque cannot be generated in the fourth combustion. However, if sufficient torque can be generated by subsequent combustion, the engine 101 can be started successfully.

On the other hand, it is also necessary to open the intake valve 105 at the first explosion pressure at the start of the engine. Therefore, when the driving load for opening the intake valve 105 in the first intake stroke is large, The increase in the rotation of the crankshaft is inhibited, and the starting performance of the engine is greatly reduced.

Thus, in the first intake stroke when performing the engine's automatic start, much of the energy due to the first explosion is opened rather than being consumed to intake a sufficient amount of air to generate torque. It is desirable to avoid situations that would otherwise be consumed for driving. Therefore, by reducing the load of the opening drive of the intake valve 105 in the first intake stroke, it is possible to increase the auto start success rate of the engine.

Therefore, a value smaller than the value required for starting the engine is set as the target value for automatic start, and the target value for the automatic start of the engine is the minimum valve operating angle and the minimum in the variable valve lift mechanisms 112a and 112b. The valve lift amount may be set, and the minimum valve operating angle and the minimum valve lift amount may respectively be zero.

However, in a four-cylinder engine or the like having a longer combustion interval than the six-cylinder engine, when the combustion that generates torque in sequence from the start of the engine is not executed, the engine rotational speed fluctuates greatly and the starting performance is lowered. In this case, therefore, the target value for the automatic start of the engine is set so that the substantial amount of air sucked in during the first intake stroke can be secured while taking into account the rotational rise caused by the first explosion pressure.

In the above automatic starting, the crankshaft starts to rotate by combustion of fuel in the combustion chamber. Therefore, when the allowable torque is increased by increasing the rotational energy obtained by the first combustion or by reducing the friction that consumes the rotational energy. The engine 101 can be restarted with a high probability by the automatic starting of the engine.

In this way, the valve operating angle and the valve lift amount of the intake valve 105 can be reduced, so that the engine can be started automatically in a state where the load of the variable valve lift mechanisms 112a and 112b is small so that the valve can be operated before the engine stops. The operating angle and the valve lift amount are forcibly set to smaller values than when starting with the starter motor.

The variable valve lift mechanisms 112a and 112b transmit the driving force from the crankshaft to the valve lifter 2a of the intake valve 105 by a complicated mechanism. Accordingly, in the case of the standard valve operating angle and the standard valve lift amount, as shown in FIG. 6, as compared with the case where the intake valve 105 is directly driven by the cam supported in the axial direction on the camshaft, The starting torque required to drive the crankshaft at the time of automatic start of the engine is greatly increased.

However, as shown in FIG. 6, when the valve operating angle and the valve lift amount are greatly reduced, the intake valve 105 is directly driven by a cam supported by the cam shaft in the starting torque of the crankshaft. It is possible to reduce more.

In addition, if automatic start is performed in a state where the starting torque of the crankshaft is lowered, the engine rotation can be started in good response as soon as the first combustion occurs, thereby improving the engine auto start success rate.

In step S208, the cylinder stopped at the expansion stroke is stored as the cylinder to be fuel-injected and ignited first upon restart.

In addition, while the engine 101 is stopped by the automatic stop, the variable valve lift mechanisms 112a and 112b are kept in a state in which the valve operating angle and the valve lift amount become target values for automatic start, so as to prepare for restarting. do.

Next, automatic start control from the auto stop state of the engine will be described with reference to the flowchart of FIG. 7.

In step S301, it is determined whether the start condition is satisfied.

Here, if any one of the following conditions (1) to (4) is satisfied, it is determined that the starting condition is satisfied.

(1) The brake switch 120 is OFF.

(2) Accelerator opening is not entirely closed.

(3) The duration time of the stopped state of the engine exceeded the reference time.

(4) The battery voltage is below the reference voltage.

However, the start condition is not limited to the above.

If the start condition is established, the process proceeds to step S302, in which fuel injection is carried out to the cylinder stopped in the expansion stroke stored in step S208, and then immediately ignited.

In the six-cylinder V-type engine 101, for example, as shown in FIG. 8, when the cylinder stopped in the expansion stroke is the sixth cylinder belonging to the left bank, the sixth cylinder is changed in accordance with the occurrence of the restart request. A predetermined amount of fuel is injected from the fuel injection valve 131 into the combustion chamber, and the fuel injected just before the ignition with the spark plug 122 of the sixth cylinder is ignited and combusted.

Further, the piston of the sixth cylinder is lowered by the explosion pressure caused by the combustion of the fuel, and the crankshaft starts to rotate to start the engine 101.

When the sixth cylinder is the expansion stroke, the third cylinder belonging to the right bank is in the intake stroke that opens the intake valve 105. However, since the valve operating angle and valve lift amount controlled by the variable valve lift mechanisms 112a and 112b of both banks are controlled to the target values for automatic start, the intake valve 105 of the third cylinder is driven to open. The load to be made is suppressed small.

For this reason, the starting torque at the time of starting to rotate the crankshaft at the explosion pressure of the first sixth cylinder is reduced, and the rotation speed of the crankshaft can be increased with good response by the first explosion, thereby improving the success rate of automatic starting. (See Fig. 9).

In the next step S303, fuel injection and ignition are performed for the cylinder stopped in the compression stroke.

In the engine 101, the ignition is performed in the order of the first cylinder, the second cylinder, the third cylinder, the fourth cylinder, the fifth cylinder, and the sixth cylinder. It is possible to easily determine which cylinder is stopped in the compression stroke based on.

In the example shown in FIG. 8, the 1st cylinder which belongs to a right bank is a cylinder stopped in a compression stroke, and after fuel injection and ignition with respect to a 6th cylinder, a fuel is injected and ignited with a 1st cylinder, and in a 6th cylinder Explosive combustion is followed by explosive combustion in the first cylinder to continue to rotate the crankshaft which began to rotate at the explosion pressure in the sixth cylinder, thereby further increasing the rotational speed.

After fuel injection and ignition to the cylinder stopped in the compression stroke, fuel injection and ignition are performed in the ignition sequence.

In addition, the fuel injection timing at the time of automatic start of an engine is judged as an intake stroke.

In step S304, the start of control for increasing and changing the valve operating angle and valve lift amount controlled by the variable valve lift mechanism 112 (112a or 112b) of the bank to which the cylinder stopped in the expansion stroke increases from the target value for automatic start-up. Determine whether it is timing.

Although the valve operating angle and the valve lift amount of the intake valve 105 were forcibly reduced in order to reduce the open drive load of the intake valve 105 in the first intake stroke, in this case, the amount of intake air is small and sufficient generation occurs. Can't get torque For this reason, if the amount of intake air is small also in the next intake stroke, the rotation will be lowered.

Therefore, it is necessary to make the valve operating angle and the valve lift amount larger than the target value for automatic start so that the sufficient intake air amount can be sucked for the second intake stroke from the start of the auto start.

Therefore, in consideration of the response delay of the variable valve lift mechanism 112, the point of time as early as the response delay time from the start of the second intake stroke is increased from the target value for the automatic start of the valve operating angle and valve lift amount. It is set as the start timing of control to change.

In this step, however, the start timing may be a point in time when the cylinder stopped in the compression stroke becomes a top dead center when the automatic stop is performed. According to this, after completion of the first compression work, the valve operating angle and the valve lift amount of the intake valve 105 are increased.

From the time when the cylinder stopped at the compression stroke becomes the top dead center, if the increase in the valve operating angle and the valve lift amount is started, the driving load of the intake valve 105 becomes large during the first compression work, and the engine rotational speed is increased. It is possible to prevent the rise of.

If it is determined that the time started from the automatic start is in timing to start control, the flow proceeds to step S305, where the valve operating angle controlled by the variable valve lift mechanisms 112 (112a, 112b) of the bank to which the cylinder stopped in the expansion stroke belongs. And control to incrementally change the valve lift amount from a target value for automatic start of the engine to a value required for continuation of the engine start.

In step S306, it is determined whether or not the delay period has elapsed from the start of the control in step S305.

Although the said delay period can be made into a fixed time, Preferably, engine rotation by one stroke is made into the said delay period.

When the delay period has elapsed, the process proceeds to step S307, in which the valve operating angle and the valve lift amount controlled by the variable valve lift mechanism 112 of the bank to which the cylinder stopped in the expansion stroke does not belong are set for automatic start of the engine. From the target value, control for increasing and changing the target value required for the continuation of the engine start is started.

In the automatic start, the valve operating angle and the valve lift amount of the intake valve 105 in the first intake stroke after the start of the start are forcibly reduced, whereby the starting torque of the crankshaft is reduced to increase the starting performance. However, in the second intake stroke, it is necessary to increase the valve operating angle and the valve lift amount so that the amount of intake air that can continue the engine start is obtained.

In the example shown in FIG. 8, the cylinder which becomes an intake stroke for the first time after starting start is the 3rd cylinder of the right bank, and the opening drive of the intake valve 105 by a large valve operating angle and a valve lift amount is avoided during an initial expansion stroke. In view of the above, it is necessary to reduce the valve operating angle and the valve lift amount of the intake valve 105 in the first intake stroke of the third cylinder.

However, for the fourth cylinder to be the second intake stroke, it is necessary to secure the amount of intake air that can continue the engine start rather than reduce the drive load of the intake valve 105. In view of this, the left bank may start controlling to increase and change the valve operating angle and the valve lift amount immediately after the start of the start.

However, when the actuator 17 is operated before the first top dead center to increase the valve operating angle and the valve lift amount with respect to the left bank, the engine which starts to rotate with the first explosion combustion and compresses the intake air amount of the first cylinder It becomes resistance of 101, slowing down the rotational rise.

Therefore, even if the start timing of the control for increasing the valve operating angle and the valve lift amount of the left bank is early, it is better to be after the top dead center of the first cylinder, and furthermore, since it is more preferable that it is a later time after the top dead center, the fourth cylinder Set at the latest time to increase the valve operating angle and the valve lift amount at the intake stroke.

Specifically, for example, the start of control to increase the valve operating angle and the valve lift amount in the left bank at a time point earlier by the response delay time from the opening time of the intake valve 105 in the valve operating angle after the increase control. Timing

Moreover, the start timing of control which increases the valve operating angle and valve lift amount of the left bank can be set based on the angle from the end time of the intake stroke of the third cylinder of the right bank.

Further, when the control for increasing the valve operating angle and the valve lift amount of the left bank and the control for increasing the valve operating angle and the valve lift amount of the right bank are started, the valve operating angle in the intake stroke of the third cylinder and The valve lift amount is increased, and overlaps with the increase in the valve operating angle and the valve lift amount in the intake stroke of the second fourth cylinder, so as to drive a large opening for driving the opening of the intake valve 105 at the beginning of the automatic start of the engine. The additional load is consumed.

The control to increase the valve operating angle and the valve lift amount of the right bank is started at a time difference with respect to the control start of the left bank. When the time difference is set to one stroke, at least the first intake stroke of the third cylinder is started. It is possible to avoid the increase in the valve operating angle and the valve lift amount at, so that the first intake stroke of the third cylinder is performed with the valve operating angle and the valve lift amount being small.

That is, for the intake stroke of the right bank, the first intake stroke is executed with the valve operating angle and the valve lift amount small, increasing to the larger valve operating angle and the valve lift amount that can continue the engine starting from the next intake stroke. do.

However, when the load by operating the actuator 17 with respect to the load of the open drive of the intake valve 105 is small enough to be negligible, the valve operating angle and valve lift of the bank to which the cylinder stopped in the expansion stroke belongs. Control to increase the amount can be started with the start of the automatic start, and control to increase the bank operating angle and valve lift amount of the other bank can be started after the initial intake stroke of the bank is finished.

In the above, the left and right banks have a time lag in starting the control to increase the valve operating angle and the valve lift amount. However, when the control is started at the same time, the valve operating angle and Control to increase the valve lift amount can be started.

In addition, the start time of the control which increases the valve operating angle and the valve lift amount can be determined based on the determination of the start of the engine 101. For example, it is determined that starting is completed when it is determined that the rotational speed of the engine or the acceleration of the engine rotational speed has exceeded the reference value, and then to the variable valve lift mechanism 112 of the bank to which the cylinder which becomes the intake stroke belongs. The control for increasing or changing the valve operating angle and the valve lift amount at the same time with respect to the variable valve lift mechanisms 112a and 112b of the two banks can be started.

In this case, the start timing of the step S304 is a time when it is determined that the rotational speed of the engine or the acceleration of the engine rotational speed has exceeded the reference value.

Moreover, with the variable valve lift mechanism 112 which changes the valve operating angle and valve lift amount of the intake valve 105, the variable valve lift which changes the valve operating angle and valve lift amount of the exhaust valve 107 is variable. When the mechanism is provided, the valve operating angle and the valve lift amount of the exhaust valve 107 are forcibly set to be small together with the intake valve 105 at the time of automatic start, and the valve operating angle and the valve lift of the intake valve 105 are forcibly set. It is possible to start increasing the amount and increasing the valve operating angle and the valve lift amount of the exhaust valve 107 with a time difference.

The variable valve mechanism is not limited to the variable valve lift mechanism 112. For example, the variable valve mechanism may be a variable valve mechanism for varying the opening characteristic of the engine valve by switching between a three-dimensional cam or a plurality of cams. The present invention is widely applicable to an engine having a variable valve mechanism for varying the valve operating angle and / or the valve lift amount of the engine valve.

Moreover, in the electromagnetic drive valve which opens and closes an engine valve using an electromagnet, by forcibly reducing the valve operating angle at the time of automatic start, the load of an electromagnetic drive valve can be reduced and the success rate of automatic start can be improved.

In addition, it is possible to judge the success or failure of the auto start from the engine rotation speed or the acceleration of the engine rotation speed after the start of the auto start, and when the auto start fails, the starter motor is automatically driven to restart the engine. .

The engine 101 is not limited to a V-type engine, and may be a horizontally opposed engine or a series engine.

All the content of the Japan patent application 2007-058958 for which it applied on March 8, 2007 is integrated in this specification by reference.

It is apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the present invention as set forth in the appended claims, as the selected embodiments are selected to illustrate and explain the present invention. .

In addition, the above description of the embodiments according to the present invention is for illustration only and is not intended to limit the present invention and equivalents thereof defined in the claims.

1 is a block diagram schematically showing a general structure of an engine embodying the present invention.

2 is a perspective view showing a variable valve lift mechanism according to an embodiment of the present invention.

3 is a partial cross-sectional side view of a variable valve lift mechanism according to an embodiment of the present invention.

4 is a cross-sectional view showing a variable valve timing mechanism according to an embodiment of the present invention.

5 is a flowchart illustrating a process of controlling automatic stop of engine operation according to an embodiment of the present invention.

6 is a graph showing the correlation between the valve operating angle of the intake valve, the valve lift amount of the intake valve and the starting torque of the crankshaft in the embodiment of the present invention.

7 is a flowchart showing restart operation control of the engine after the engine is automatically stopped in the embodiment of the present invention.

8 is a time chart showing fuel injection timing, ignition timing and intake stroke when restarting the operation of the engine in the embodiment of the present invention.

9 is a time chart showing the behavior of the engine speed when restarting the operation of the engine in the embodiment of the present invention.

Claims (19)

In the engine start control apparatus provided with the variable valve mechanism which makes the opening characteristic of an engine valve variable, Starting means for starting the engine operation by igniting fuel in the combustion chamber of the engine when the operation of the engine is stopped; And a load control means for forcibly lowering the load consumed by the variable valve mechanism at the start of the engine operation by the start means. The start control apparatus for an engine according to claim 1, wherein the load control means continuously maintains a state in which the load of the variable valve mechanism is forcibly reduced by one stroke of the engine. The start control apparatus for an engine according to claim 1, wherein the load control means continuously maintains a state in which the load of the variable valve mechanism is forcibly reduced to the first compression top dead center. The start control apparatus for an engine according to claim 1, wherein the load control means keeps the state in which the load of the variable valve mechanism is forcibly lowered until completion of starting of the engine operation is determined. The load control means according to any one of claims 1 to 4, by forcibly controlling the opening characteristic so that the load consumed for opening the engine valve is small, thereby forcibly controlling the load of the variable valve mechanism. Starting control device of the engine, characterized in that the lowering. The start control apparatus for an engine according to claim 5, wherein the load control means forcibly controls the opening characteristic so that the load consumed for opening the engine valve is small when the engine operation is stopped. The said variable valve mechanism is a mechanism which changes the valve lift amount of the said engine valve, And the load control means forcibly lowers the valve lift amount, thereby forcibly lowering the load consumed for opening the engine valve. The said variable valve mechanism is a mechanism which changes the valve operating angle of the said engine valve, And the load control means forcibly lowers the valve operating angle, thereby forcibly lowering the load consumed for opening the engine valve. The method of claim 1, wherein the variable valve mechanism is composed of a plurality of the same variable valve mechanism installed independently of each other, The load control means forcibly lowers the load of the variable valve mechanism by controlling each of the plurality of independent variable valve mechanisms so that the opening characteristic of the engine valve can be changed at a time difference between the plurality of independent variable valve mechanisms. Starting control device of the engine, characterized in that. 10. The engine of claim 9, wherein the engine includes two banks each provided with the variable valve mechanism. And the load control means controls the variable valve mechanism of each of the two banks so that a change in the opening characteristic can be executed at a time difference between the variable valve mechanisms of the two banks. The load control means according to claim 9 or 10, wherein the load control means is characterized in that the load consumed for opening the drive of each of the engine valves is small from the opening characteristic of the load consumed to drive the opening of each of the engine valves. And controlling the plurality of independent variable valve mechanisms so that a change can be made at a time difference between the plurality of variable valve mechanisms. In the start control method of the engine provided with the variable valve mechanism which makes the opening characteristic of an engine valve variable, Determining an occurrence of a start request of the engine; Starting the engine operation by igniting fuel in the combustion chamber of the engine when the operation of the engine is stopped; Forcibly lowering the load consumed by the variable valve mechanism at the start of the engine operation. The method of claim 12, wherein forcibly lowering the load of the variable valve mechanism includes: Determining whether a period of one stroke of the engine has elapsed from the start of the engine; Forcibly lowering the load of the variable valve mechanism for a duration until the period elapses. The method of claim 12, wherein forcibly lowering the load of the variable valve mechanism includes: Determining whether a period from the start of the engine to the first compression top dead center has elapsed; Forcibly lowering the load of the variable valve mechanism for a duration until the period elapses. The method of claim 12, wherein forcibly lowering the load of the variable valve mechanism includes: Determining whether or not the start of the engine is completed; Forcibly lowering the load of the variable valve mechanism for a duration until the start-up of the engine is determined to be complete. The method of claim 12, wherein forcibly lowering the load of the variable valve mechanism includes: Determining whether the operation of the engine is stopped or not; Controlling the variable valve mechanism, aiming at the engine valve to have an open characteristic with a small load of the open drive of the engine valve when it is determined that the engine operation is stopped. Control method. 13. The variable valve mechanism according to claim 12, wherein the variable valve mechanism is composed of a plurality of identical variable valve mechanisms independent of each other, Forcibly lowering the load of the variable valve mechanism, Changing the opening characteristic of the engine valve for some of the plurality of variable valve mechanisms; Determining whether a predetermined delay time has elapsed from the change of the opening characteristic of the engine; And after the delay time has elapsed, changing the opening characteristic of the engine valve to another variable valve mechanism other than the change of the opening characteristic except for the partial variable valve mechanism. Start control method. 18. The engine of claim 17, wherein the engine has first and second banks each having the variable valve mechanism, Causing the opening characteristic of the engine valve to be changed for some of the plurality of variable valve mechanisms, controlling to change the opening characteristic of the engine valve with respect to the variable valve mechanism of the first bank, Controlling another variable control valve to change the opening characteristic of the engine valve after the delay time has elapsed includes controlling to change the opening characteristic of the engine valve with respect to the variable valve mechanism of the second bank. Start control method of the engine, characterized in that. 19. The method according to claim 17 or 18, wherein the opening characteristic of the engine valve is changed for some of the plurality of variable valve mechanisms, and after the delay time has elapsed, The step of changing the opening characteristic is to start the engine, characterized in that for the plurality of valve mechanisms, the opening characteristic of the engine is changed so that the loads of the open drive of the engine valve are respectively changed from a small load state to a large load state. Control method.

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