JP2012172566A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mitigate or eliminate a delay and slow restart of an internal combustion engine with an idle stop system.SOLUTION: In idle stop, the opening of a throttle valve is reduced to be equal to or smaller than a predetermined opening. When engine speed is equal to or lower than a predetermined value, the throttle valve with the reduced opening is temporarily opened larger than the predetermined opening, and is reclosed. When an accelerator pedal is depressed during idle stop control, the opening of the throttle valve is operated to be set to a required opening or larger according to the pressing amount of the accelerator pedal.

Description

  The present invention relates to a control device for an internal combustion engine that realizes an idling stop function.

  There is known an idling stop system that automatically stops idle rotation of an internal combustion engine when the vehicle is temporarily stopped, such as waiting for a signal, and improves fuel consumption (see, for example, the following patent document).

  When performing idling stop, the throttle valve opening is reduced to a predetermined opening or less, and fuel supply to the cylinder is shut off. However, the rotation of the internal combustion engine does not stop immediately, and the air pressure in the intake passage (particularly, the surge tank) significantly decreases during the period from the establishment of the idle stop condition to the complete stop of the internal combustion engine. Then, when the internal combustion engine is restarted, the necessary and sufficient amount of intake air cannot be quickly charged into the cylinder, and the restart is delayed, resulting in a delay in the restart of the vehicle.

JP 2006-2558078 A

  An object of the present invention is to alleviate or eliminate the delay and delay of an internal combustion engine associated with an idling stop system.

  In the present invention, the idling stop function is realized. When performing idling stop, the throttle valve opening is throttled to a predetermined opening or less, and when the engine speed becomes a predetermined value or less, the throttle valve that has been throttled is temporarily stopped. While performing an idle stop control that opens larger than the predetermined opening and then closes again, and when the accelerator pedal is depressed during the idle stop control, the opening of the throttle valve is set to the depression of the accelerator pedal. A control device for an internal combustion engine, which is operated so as to be equal to or more than the required opening degree according to the amount of quantity, is configured.

  That is, in the idle stop control, when the engine speed becomes less than a predetermined value, the throttle valve is once opened to increase the air pressure in the intake passage (surge tank) to a certain extent and for smooth restart. Ensure a minimum amount of intake (fresh air). In addition, if the accelerator pedal is depressed before the internal combustion engine is completely stopped, the throttle valve opening is increased according to the amount of depression, and more intake air is introduced into the intake passage and restarted. The engine output immediately after that can be increased.

  The required opening corresponding to the amount of depression of the accelerator pedal during idle stop control is set smaller than the throttle valve opening corresponding to the same accelerator pedal depression during normal times when idle stop control is not being performed. The intention is to suppress the sudden start of the vehicle without excessively increasing the engine output at the time of restart.

  It is also preferable to increase the required opening according to the amount of depression of the accelerator pedal during the idle stop control not behind the increase of the accelerator pedal depression amount but behind the increase of the accelerator pedal depression amount. When the engine speed decreases due to idle stop control, the hydraulic pressure supplied to the transmission also decreases. When the internal combustion engine is restarted in this state and the engine output increases sharply, it slips between mechanical elements that constitute the transmission, for example, between the belt and pulley of a clutch or a belt-type continuously variable transmission mechanism (Continuously Variable Transmission). Then, the hydraulic pressure increases and the clutch and the like are firmly fastened, which may cause a shock and damage the transmission. By delaying the expansion of the throttle valve opening relative to the depression of the accelerator pedal, it is possible to suppress an increase in engine output at the time of restart, prevent slippage in the mechanical elements of the transmission, avoid a shock, and protect the transmission.

  According to the present invention, it is possible to mitigate or eliminate the delay due to the restart of the internal combustion engine attached with the idling stop system.

The figure which shows the structure of the internal combustion engine in one Embodiment of this invention. The flowchart which shows the procedure of the process which the control apparatus of the embodiment performs according to a program. The timing chart which shows the aspect of the idle stop control by the same embodiment. The timing chart which shows the aspect of the idle stop control by the same embodiment. The timing chart which shows the aspect of the idle stop control by the modification of this invention.

  An embodiment of the present invention will be described with reference to the drawings. A spark ignition internal combustion engine 0 schematically showing the configuration of one cylinder in FIG. 1 is mounted on, for example, an automobile. The intake system 1 of the internal combustion engine 0 is provided with an electronic throttle valve 11 whose opening is operated in accordance with the amount of depression of the accelerator pedal, and an intake manifold 12 integrally having a surge tank 13 is provided downstream of the throttle valve 11. It is attached. The surge tank 13 is provided with a pressure sensor 71 for detecting the intake pipe pressure (intake negative pressure or supercharging pressure).

An exhaust manifold 51 is attached to the exhaust system 5 and a three-way catalyst 52 for exhaust gas purification is attached. A front O ₂ sensor 53 is disposed upstream of the catalyst 52, and a rear O ₂ sensor 54 is disposed downstream. The O ₂ sensors 53 and 54 output a voltage signal corresponding to the oxygen concentration in the exhaust gas by reacting in contact with the exhaust gas.

  An EGR device 6 is interposed between the intake system 1 and the exhaust system 5. The EGR device 6 includes an external EGR passage 61 having a start end communicating with the exhaust manifold 51 and a terminal end communicating with the surge tank 13, and an external EGR valve 62 provided on the EGR passage 61. If the EGR valve 62 is opened, an external EGR that recirculates the exhaust gas from the exhaust system 5 to the intake system 1 and mixes it with the intake air can be realized.

  An intake valve 21, an exhaust valve 22, an injector 3, and a spark plug 23 are provided on the ceiling portion (cylinder head) of the combustion chamber formed in the upper part of the cylinder 2.

  An electronic control unit 4 that controls the operation of the internal combustion engine 0 is a microcomputer system having a central processing unit 41, a storage device 42, an input interface 43, an output interface 44, and the like.

The input interface 43 includes an intake pressure signal a output from the pressure sensor 71 that detects the pressure in the intake pipe, a rotation speed signal b output from the rotation speed sensor 72 that detects the engine speed, and a vehicle speed sensor 73 that detects the vehicle speed. A vehicle speed signal c output from the vehicle, an accelerator signal d output from the accelerator sensor 74 that detects the amount of depression of the accelerator pedal (or the opening of the throttle valve 11), a shift position signal e output from the shift position switch 75, A water temperature signal f output from a water temperature sensor 76 that detects the temperature of the cooling water, a crank angle signal output from a timing sensor 93 at the end of the intake camshaft 91, a cylinder discrimination signal g, and an end of the exhaust camshaft 92 Output every 240 ° CA (crank angle) rotation from the timing sensor 94 Air cam signal h, the front O ₂ upstream air-fuel ratio signal i output from the sensor 53, the downstream-side air-fuel ratio signal j outputted from the rear O ₂ sensor 54, the output from the brake sensor 77 for detecting the amount of depression of the brake pedal The brake signal k etc. to be output is output. The engine rotation speed sensor 72 detects the rotation speed of the crankshaft by sensing the passage of teeth formed intermittently every 10 ° CA on the outer periphery of the disk rotating together with the crankshaft.

  From the output interface 44, the fuel injection signal n for the injector 3, the ignition signal m for the spark plug 8, the EGR valve opening signal o for the EGR valve 62, and the throttle opening signal for the electronic throttle valve 11. l etc. are output.

  The central processing unit 41 interprets and executes a program stored in advance in the storage device 42, and performs fuel injection amount and ignition timing of the internal combustion engine 0, intake air amount filled in the cylinder 2, and EGR rate of intake air (EGR gas amount). The amount of reflux) is controlled.

  In the operation control of the internal combustion engine 0, the ECU 4 sends various information a, b, c, d, e, f, g, h, i, j, k necessary for the operation control of the internal combustion engine 0 via the input interface 43. Further, the current intake air amount and the EGR rate of the intake air are estimated, and based on them, the fuel injection amount, the fuel injection timing, the ignition timing, the opening degree of the EGR valve 62 (the number of EGR steps), which are control inputs, The opening degree of the electronic throttle valve 11 is calculated. Then, control signals l, m, n, and o corresponding to the calculated control input are applied through the output interface 44.

  Therefore, ECU4 which is a control apparatus of this embodiment performs control for implement | achieving an idling stop function.

  A procedure of processing executed by the ECU 4 when idling is stopped will be described. As shown in FIG. 2, when the idle stop condition is satisfied (stop S1), the ECU 4 shifts to the idle stop control in steps S2 to S5. In step S1, for example, the vehicle speed is a predetermined value (about 7 km / h) or less, the cooling water temperature is higher than a predetermined value, the shift position is the travel range (AT vehicle), the brake pedal is depressed, etc. When all the conditions are met, idle stop control is started.

  In the idle stop control, fuel injection (and ignition) from the injector 3 is stopped (step S2), and the opening of the electronic throttle valve 11 is fully closed or a predetermined opening close to full closing. The reason for closing the throttle valve 11 is to quickly reduce the engine speed. In principle, the throttle valve 11 is kept throttled until the engine speed drops below a predetermined speed. The predetermined rotational speed mentioned here is a specific rotational speed near or below the upper limit at which the pinion gear of the starter (cell motor) can be meshed with the ring gear on the outer periphery of the drive plate (AT car) or flywheel (MT car). (About 300 rpm). If the engine speed is higher than the predetermined speed, the pinion gear cannot be engaged with the ring gear even if the restart condition is satisfied, and cranking cannot be performed.

  When the engine speed has decreased to the predetermined speed, the throttle valve 11 that has been throttled is once opened to be larger than the predetermined opening, and then the throttle valve is closed again to the predetermined opening. Even after the fuel supply to the cylinder 2 is stopped, the internal combustion engine 0 continues to rotate for a while, and operates to suck the gas in the intake manifold 12 and the surge tank 13 into the cylinder 2 and send it to the exhaust system 5. The throttle valve 11 that has been throttled is temporarily opened by refilling the surge tank 13 with fresh air and quickly filling the cylinder 2 with the amount of intake air necessary for restart when the restart condition is satisfied. Because.

  FIG. 3 shows the change in the opening of the electronic throttle valve 11 and the change in the intake pipe pressure when the accelerator pedal is not depressed until the internal combustion engine 0 is completely stopped and the following restart condition is not satisfied. Is. The ECU 4 closes the throttle valve 11 to a predetermined opening or less (fully closed in the illustrated example) at time t0 when the idle stop condition is satisfied, and maintains the engine speed until the engine speed decreases to a predetermined rotation speed or less. Then, the opening of the throttle valve 11 is opened from the predetermined opening at time t1 when the engine speed reaches the predetermined rotating speed, and the throttle valve 11 is closed again at time t2 when the required time has elapsed. The opening degree of the throttle valve 11 is closed to a predetermined opening degree (fully closed in the illustrated example) before the internal combustion engine 0 is completely stopped. The time series of the throttle valve opening as shown in FIG. 3, in other words, the operation pattern of the reference opening of the throttle valve 11 in the idle stop control is stored in the storage device 42 in advance. The ECU 4 obtains the reference opening of the throttle valve 11 during the idle stop control by reading the information stored and held in the storage device 42 (step S3).

  When the restart condition is satisfied after the transition to the idle stop control (step S6), the process proceeds to the restart control in steps S7 to S8. In step S6, for example, the foot is released from the brake pedal, the shift position is changed to the non-traveling range, the accelerator pedal is stepped on, the vehicle speed increases above a predetermined value, or the internal combustion engine 0 is stopped for a predetermined time. It is determined that a restart request has been made when (approximately 3 minutes) has elapsed. However, as described above, the internal combustion engine 0 cannot be cranked and restarted unless the engine speed has decreased to a predetermined speed or less. Therefore, the restart condition in step S6 includes that the engine speed is equal to or lower than the predetermined speed.

  In the restart control, the pinion gear of the starter motor is engaged with the drive plate or the ring gear on the outer periphery of the flywheel to perform cranking (step S7), and fuel injection (and ignition) from the injector 3 is resumed ( Step S8) The internal combustion engine 0 is restarted.

  In addition, when the accelerator pedal is depressed by the driver before the internal combustion engine 0 is completely stopped during the idle stop control, an operation for increasing the opening of the electronic throttle valve 11 according to the depression amount. I do. In other words, when the accelerator pedal is depressed, it means that the driver is requesting a relatively large engine output, and a request corresponding to the amount of depression of the accelerator pedal is required to meet the explicit demand. The opening is realized, and the intake amount and fuel injection amount charged in the cylinder 2 immediately after restarting are increased.

  In general, the opening degree of the electronic throttle valve 11 during the idling stop control and not during idling increases as the amount of depression of the accelerator pedal increases. The required opening during the idle stop control is the same as that point, but the required opening during the idle stop control with respect to the accelerator pedal depression amount is set smaller than the normal throttle valve opening with respect to the same accelerator pedal depression amount.

  During the idle stop control, the ECU 4 refers to the amount of depression of the accelerator pedal to determine the required opening according to the amount (step S4), and stores the required opening and the current time stored in the storage device 42. If the required opening is larger, the throttle valve 11 is operated to the required opening, and if the reference opening is larger, the throttle valve 11 is operated to the reference opening (step) S5).

  FIG. 4 shows the transition of the opening degree of the electronic throttle valve 11 and the intake pipe pressure when the accelerator pedal is depressed during the period from the transition to the idle stop control until the engine speed becomes equal to or lower than the predetermined speed. It shows the transition. The broken line in the figure is the time series of the reference opening stored in the storage device 42, and the alternate long and short dash line is the required opening corresponding to the accelerator pedal depression amount. The ECU 4 attempts to maintain the throttle valve 11 until the engine speed decreases to a predetermined value or less by closing the throttle valve 11 to a predetermined value or less at time t0 when the idle stop condition is satisfied. However, if the accelerator pedal is depressed before time t1 when the engine speed reaches the predetermined number of revolutions, as shown by the solid line in the figure, the required opening according to the amount of depression of the accelerator pedal from that time t3 The throttle valve 11 is opened and operated at the above opening. From the time t1 when the engine speed becomes equal to or lower than the predetermined speed to the time t2, the reference opening may be larger than the required opening. If so, the throttle valve 11 is moved to the reference opening. Open operation according to the operation pattern. Of course, if the accelerator pedal is depressed strongly and the required opening exceeds the reference opening, the throttle valve 11 is still operated to the required opening after time t1.

  In the present embodiment, when the idling stop is performed by the control device 4 of the internal combustion engine 0 that realizes the idling stop function, the opening of the throttle valve 11 is throttled to a predetermined opening or less, and is throttled when the engine speed becomes a predetermined or less. When the throttle valve 11 that has been opened is temporarily opened larger than the predetermined opening degree and then closed again, the idle stop control is executed, and when the accelerator pedal is depressed during the idle stop control, the throttle valve 11 It was decided to operate the opening so as to be not less than the required opening according to the amount of depression of the accelerator pedal. That is, the throttle valve 11 is once opened before the restart request, and the air pressure in the surge tank 13 is increased to a certain extent, so that a sufficient amount of intake air necessary for restart can be ensured, and smooth and quick restart and restart can be performed. It becomes possible. In addition, when the accelerator pedal is depressed before the internal combustion engine 0 is completely stopped, the opening of the throttle valve 11 is operated so as to be equal to or greater than the required opening corresponding to the amount of depression, so that a larger amount of intake air is generated. Introduced into the surge tank 13, the engine output immediately after restart can be increased in response to the explicit demand of the driver.

  Further, the required opening corresponding to the amount of depression of the accelerator pedal during the idle stop control is set smaller than the throttle valve opening corresponding to the same accelerator pedal depression during normal times when the idle stop control is not being performed. For this reason, it is possible to prevent an excessive increase in engine output at the time of restart, and to suppress the sudden start of the vehicle and the occurrence of slipping in the mechanical elements constituting the transmission.

  The present invention is not limited to the embodiment described in detail above. In the embodiment described above, the required opening degree is increased simultaneously with the increase of the accelerator pedal depression amount. On the other hand, it is also conceivable that the required opening degree is not increased at the same time as the accelerator pedal depression amount is increased, but is increased after the accelerator pedal depression amount is increased.

  When the engine speed decreases due to idle stop control, the hydraulic pressure supplied to the transmission also decreases. In this state, when the internal combustion engine is restarted and the engine output rapidly increases, slippage occurs between mechanical elements constituting the transmission, for example, the clutch or the belt and pulley of the CVT, and then the hydraulic pressure increases. If the clutch or the like is firmly fastened, it may cause a shock and damage the transmission. Such a problem occurs when the driver suddenly depresses the accelerator pedal suddenly during the idle stop control. Therefore, the expansion of the throttle valve opening corresponding to the required opening is delayed so that the engine output does not increase too much at the time of restart.

  FIG. 5 shows the transition of the opening degree of the electronic throttle valve 11 and the intake pipe pressure when the accelerator pedal is depressed during the period from the transition to the idle stop control until the engine speed becomes equal to or lower than the predetermined speed. It shows the transition. The broken line in the figure is the time series of the reference opening stored in the storage device 42, and the alternate long and short dash line is the required opening corresponding to the accelerator pedal depression amount. In addition, the two-dot chain line in the figure is the amount of depression of the accelerator pedal (the required opening to be achieved according to the depression amount). The ECU 4 attempts to maintain the throttle valve 11 until the engine speed decreases to a predetermined value or less by closing the throttle valve 11 to a predetermined value or less at time t0 when the idle stop condition is satisfied. Assuming that the accelerator pedal is depressed at time t3 before the time t1 at which the engine speed becomes the predetermined engine speed, it is necessary to determine the required opening according to the amount of depression of the accelerator pedal. As shown, smoothing the accelerator pedal depression amount (for example, taking a moving average of the accelerator pedal depression amount) or waiting for a certain delay time from the increase of the accelerator pedal depression amount The opening is increased after the accelerator pedal depression amount is increased. After time t3, when the required opening is larger than the reference opening, the throttle valve 11 is operated to the required opening, and conversely, when the reference opening is larger, the throttle valve 11 is operated to the reference opening. The same as the above embodiment. Depending on the degree of delay (smoothing process or delay time), even if the accelerator pedal is strongly depressed at time t3, the throttle valve 11 does not open very much until the first explosion of the restart, and the required opening degree is only after the complete explosion. There may be a case of opening to the extent.

  In addition, the specific configuration of each unit and the specific processing procedure can be variously modified without departing from the spirit of the present invention.

  The present invention can be applied to control of an internal combustion engine mounted on a vehicle or the like.

DESCRIPTION OF SYMBOLS 0 ... Internal combustion engine 11 ... Throttle valve 4 ... Control apparatus (ECU)

Claims (3)

A control device for an internal combustion engine that realizes an idling stop function,
When performing idling stop, the throttle valve opening is throttled below a predetermined opening, and when the engine speed falls below a predetermined opening, the throttle valve that has been throttled is once opened larger than the predetermined opening and then closed again. And run
When the accelerator pedal is depressed during the idle stop control, the throttle valve is operated such that the opening of the throttle valve is equal to or greater than the required opening corresponding to the amount of depression of the accelerator pedal. A control device for an internal combustion engine. The required opening according to the amount of depression of the accelerator pedal during the idle stop control is smaller than the throttle valve opening corresponding to the same accelerator pedal depression during normal times not during the idle stop control. Item 2. The control device according to Item 1. The required opening according to the amount of depression of the accelerator pedal during the idle stop control is increased not with the increase of the accelerator pedal depression amount but with an increase in the accelerator pedal depression amount. Control device.

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