WO2013042476A1

WO2013042476A1 - Engine control device

Info

Publication number: WO2013042476A1
Application number: PCT/JP2012/070190
Authority: WO
Inventors: 定藤原; 中沢　孝志; 江頭　猛
Original assignee: 日産自動車株式会社
Priority date: 2011-09-22
Filing date: 2012-08-08
Publication date: 2013-03-28
Also published as: JP2013068145A; JP6060477B2

Abstract

When the vehicle is stopped and the gear shift is in a state wherein power is not being transmitted, that is, the N range (or P range), and the pressing of the accelerator pedal continues for a prescribed time T, the throttle opening is corrected to a closed-side value TVOmin so as to prevent overheating of the exhaust system due to idling of the engine. In this state, when the driver switches the gear shift from the N range to the D range (t1), the correction of the throttle opening to the closed side is canceled. When this correction is canceled (t1-t2) the throttle opening is gradually increased, and thus a sharp increase in the vehicle drive torque is suppressed/eliminated.

Description

Engine control device

The present invention relates to an engine control device, and more particularly to control of a throttle whose opening degree can be adjusted independently of operation of an accelerator pedal.

The driver depresses the accelerator pedal consciously or unconsciously in the non-power transmission state when the vehicle is stopped and the speed change lever is in the N range or P range and the power transmission path from the engine to the drive wheels is interrupted. At this time, if the throttle opening of the throttle valve is increased in conjunction with this, the engine rotation speed increases, so-called engine idling occurs. If such an idling state continues, the engine may overheat (overheat), which may cause deterioration or damage of exhaust system parts such as a catalytic converter.

Therefore, in Patent Document 1, when the state in which the accelerator pedal is depressed while the vehicle is stopped and in a non-power transmission state elapses for a predetermined time or longer, the throttle valve is corrected to the closed side to prevent overheating due to continued idling of the engine. Is described.

Japanese Patent Laid-Open No. 10-184396

As described above, in the state where the throttle valve is corrected to the closed side while the accelerator pedal is depressed while the vehicle is stopped and in the non-power transmission state, the shift lever is moved from the N and P ranges to D for the driver to start the vehicle. By switching to the range, it may be switched to a power transmission state in which power can be transmitted from the engine to the drive wheels. At this time, if the correction on the closing side of the throttle valve is canceled and the throttle opening is immediately returned to the original target throttle opening corresponding to the accelerator opening, the throttle opening rapidly increases, so that the intake air There is a risk that the amount will increase rapidly and the vehicle drive torque will increase rapidly, giving the impression that the vehicle will inadvertently start.

The present invention has been made in view of such circumstances, and by correcting the throttle opening to a lower side when the vehicle is stopped and in a non-power transmission state, the engine is prevented from being overheated due to idling of the engine. When the throttle opening is corrected to the decrease side, when the non-power transmission state is switched to the power transmission state, the throttle opening is prevented from abruptly increasing and the vehicle driving torque increases rapidly. The purpose is to prevent.

An engine control device according to the present invention is provided in an accelerator opening detecting means such as an accelerator opening sensor for detecting an accelerator opening of an accelerator pedal operated by a driver, and an intake passage of the engine. A throttle capable of adjusting the opening degree independently of operation, and a power transmission switching means capable of switching between a power transmission state in which power can be transmitted from the engine to the driving wheel and a non-power transmission state in which power transmission is interrupted. And throttle control means for controlling the throttle opening based on the accelerator opening.

Here, when the vehicle is stopped and the accelerator pedal is continuously depressed for a predetermined time in a non-power transmission state in which the power transmission from the engine to the drive wheels is interrupted by the power transmission switching means, The throttle opening is corrected to the closed side to prevent overheating due to idling. In such a state that the throttle opening is corrected to the closed side, for example, when the driver operates the shift lever of the automatic transmission from the N range or the P range to the D range, the power transmission state is changed from the non-power transmission state. However, the present invention is characterized in that the throttle opening is gradually increased when the correction is canceled in this way. .

According to the present invention, when the accelerator pedal is depressed for a predetermined time while the vehicle is stopped and in a non-power transmission state, the throttle opening is corrected to the lower side, thereby avoiding overheating due to engine idling. As described above, when the throttle opening is corrected to the lower side, when the driver is switched from the non-power transmission state to the power transmission state by operating the shift lever, etc., the throttle opening is reduced to the lower side. Accordingly, it is possible to prevent the throttle opening from opening suddenly with the release of the torque, and to prevent a torque shock that the vehicle driving torque acts suddenly and the vehicle starts to move.

The system block diagram which shows the control apparatus of the engine which concerns on one Example of this invention. The flowchart which shows the flow of control of a present Example. The flowchart which shows the subroutine of the cancellation | release process of throttle opening correction | amendment of FIG. The timing chart which shows an example of a change of the throttle opening etc. which concern on a present Example. The timing chart which shows the other example of a change of the throttle opening etc. which concern on a present Example.

Hereinafter, the present invention will be described with reference to illustrated embodiments. FIG. 1 shows a system configuration of an engine control apparatus according to an embodiment of the present invention. An engine 1 is mounted on the vehicle, and engine-generated torque extracted from the crankshaft of the engine 1 is transmitted to drive wheels via an automatic transmission. The engine 1 is a multi-cylinder four-cycle gasoline engine. In each cylinder, air that has passed through an air cleaner 2 is sucked through an intake duct 3, an intake collector 4, an intake manifold 5, and an intake valve 6. The The intake air amount of the engine 1 is adjusted by an electronically controlled throttle 7 interposed in the intake duct 3. The electronically controlled throttle 7 is a device that opens and closes a butterfly throttle valve 7a by a throttle motor (throttle actuator) 7b. The amount of power supplied to the throttle motor 7b is controlled, so that the operation of the accelerator pedal 25 can be controlled. Can independently adjust the opening of the throttle valve 7a.

A fuel injection valve 9 is provided at the intake port of each cylinder. However, the fuel injection valve 9 may be an in-cylinder direct injection engine in which fuel is directly injected into the combustion chamber 10. The fuel injected from the fuel injection valve 9 is ignited and burned in the combustion chamber 10 by spark ignition by the spark plug 15. An ignition coil 16 having a built-in power transistor is directly attached to the ignition plug 15, and the ignition timing and ignition energy of the ignition plug 15 are adjusted by controlling energization to the ignition coil 16.

The exhaust gas in the combustion chamber 10 is discharged into the atmosphere via the exhaust valve 11, the exhaust manifold 12, and the exhaust duct 13. The exhaust duct 13 is provided with a catalytic converter 14 for purifying harmful components in the exhaust. The power transistor for controlling the energization of the throttle motor 8, the fuel injection valve 9, and the ignition coil 16 is controlled by a control signal from an engine control unit (ECU) 21 incorporating a microcomputer.

The engine control unit 21 receives detection signals from various sensors. Various sensors include an air flow sensor 22 that detects the intake air flow rate Qa (mass flow rate) of the engine 1 on the upstream side of the electronically controlled throttle 7, and an air-fuel ratio on the upstream side of the catalytic converter 14 based on the oxygen concentration in the exhaust gas. An air-fuel ratio sensor 23 to detect, a rotational speed sensor 24 to detect the rotational speed Ne (rpm) of the engine 1, an accelerator opening sensor 26 to detect an accelerator opening (operation amount) APO of an accelerator pedal 25 operated by the driver, A throttle sensor 27 that detects the throttle opening TVO (deg) of the throttle valve 7a, a vehicle speed sensor 28 that detects a traveling speed (vehicle speed) VSP (km / h) of a vehicle on which the engine 1 is mounted, and the like are provided. The accelerator operation by the driver is not limited to the depression of the accelerator pedal 25, but may be a lever operation, a grip operation, or the like.

FIG. 2 is a flowchart showing the flow of control according to this embodiment, and this routine is repeatedly executed by the engine control unit 21 at predetermined time intervals (for example, every 10 ms).

In step S10, signals representing various operating states such as the accelerator opening APO and the engine speed Ne are read. In step S11, it is determined whether the vehicle is in a stopped state, that is, whether the vehicle is stopped based on the vehicle speed VSP or the like. If the vehicle is stopped, the process proceeds from step S11 to step S12. Based on the accelerator opening APO detected by the accelerator opening sensor 26, the accelerator pedal 25 is depressed, that is, the accelerator opening APO is larger than 0. It is determined whether it is. If the accelerator pedal 25 is not depressed, this routine is terminated.

If the accelerator pedal 25 is depressed, the process proceeds from step S12 to step S13, where the power transmission from the engine to the driving wheel is interrupted, that is, whether the shift lever of the automatic transmission is in the N range or Judge whether it is P range. This determination can be made using, for example, a neutral switch that detects whether the shift lever is in the N range or the P range. If it is in the non-power transmission state, the process proceeds from step S13 to step S14, and it is determined whether a predetermined time T has elapsed since the accelerator pedal 25 was depressed while the vehicle was stopped and in the non-power transmission state. That is, it is determined whether the engine has been idle for a predetermined time T.

When the idling state has passed the predetermined time t, the process proceeds from step S14 to step S15, and the throttle opening is corrected to the lower side in order to avoid overheating due to the continuation of idling of the engine. That is, the target throttle opening is a value lower than the original value obtained based on the engine speed Ne, the accelerator opening APO, and the like, specifically, a value TVOmin that is fully closed or in the vicinity thereof (see FIGS. 4 and 5). ). In this way, overheating due to continued idling of the engine can be avoided by correcting and limiting the throttle opening to the lower side.

In step S13, when the shift lever is in the D range other than the N range or the P range and is in a power transmission state in which power transmission from the engine to the drive wheels is possible, the process proceeds to step S16, and the current driving state is described above. In step S15, it is determined whether or not the operation state is being corrected to the throttle opening decreasing side. That is, when the engine is idling, for example, when the driver switches the shift lever from the N, P range to the D range to switch from the non-power transmission state to the power transmission state, step S13 is negative, S16 is affirmed and it progresses to step S17, and the cancellation | release process of the correction to the reduction side of throttle opening is performed.

FIG. 3 is a subroutine showing details of the correction cancellation processing to the throttle opening decreasing side in step S17 of FIG. In this embodiment, the target engine torque is obtained based on the engine rotational speed Ne, the accelerator opening APO, etc., and the target throttle opening tTVO is used by using this target engine torque for the purpose of simplifying the control. Is calculated. Here, the target engine torque and the target throttle opening are in a substantially proportional relationship, and when the target engine torque decreases, the target throttle opening also decreases. Therefore, the upper limit value TQlim of the target engine torque tTQ is set, By limiting the target engine torque tTQ to the upper limit value TQlim or less, the target throttle opening can be indirectly corrected and limited to the lower side.

Then, in the correction release processing to the throttle opening decreasing side, the correction release to the target throttle opening decreasing side is gradually performed by gradually increasing the value of the upper limit value TQlim of the target engine torque, The throttle opening is gradually increased toward the original target throttle opening corresponding to the accelerator opening.

Specifically, in step S21 of FIG. 3, a basic value TQ0 of the target engine torque corresponding to the engine torque corresponding to the engine operating state is calculated based on the engine rotational speed Ne, the accelerator opening APO, and the like. In subsequent step S22, an upper limit value TQlim of the target engine torque is calculated. As described above, the upper limit value TQlim is a value for gradually canceling the correction to the throttle opening decreasing side, and in this embodiment, the amount of increase in the target throttle opening during correction cancellation per time Is set so that the target throttle opening increases at a constant rate of change and rate of change. As described above, by increasing the target throttle opening degree during the cancellation of the correction at a constant change speed, it is possible to realize a smooth vehicle start without a torque shock.

In the processing from step S23 to step S26, the smaller one of the basic value TQ0 and the upper limit value TQlim is selected and set as the target engine torque tTQ. Specifically, in step S23, it is determined whether the basic value TQ0 is equal to or higher than the upper limit value TQlim, that is, whether the upper limit value TQlim is lower than the basic value TQ0. If the basic value TQ0 is equal to or higher than the upper limit value TQlim. In step S24, the smaller upper limit value TQlim is set as the target engine torque tTQ. On the other hand, if the basic value TQ0 is less than the upper limit value TQlim and the upper limit value TQlim exceeds the basic value TQ0, the process proceeds from step S23 to step S25, and the correction cancellation is completed, and the upper limit value TQlim is set to the maximum output or higher. By raising the value to the maximum value TQmax corresponding to this value and making the upper limit value substantially invalid, the correction cancellation restriction using the upper limit value (that is, the process of gradually performing correction cancellation) is completed. . In step 26, the basic value TQ0 obtained in accordance with the operating state is selected and set as the target engine torque tTQ.

In step S27, the target throttle opening tTVO is calculated based on the target engine torque tTQ set in step S24 or step S26. As described above, the target throttle opening is set in a form that is substantially proportional to the target engine torque, that is, a value that increases as the target engine torque increases and a value that decreases as the target engine torque decreases.

4 and 5 are timing charts showing changes in the throttle opening and the like when the control of this embodiment is applied. FIG. 4 shows the case where the accelerator opening is in the vicinity of full open (about 8/8 opening), and FIG. 5 shows the case where the accelerator opening is smaller than that in FIG. 4 (about 3/8 opening). In the figure, the broken line characteristic in the timing chart of the engine speed and the vehicle speed indicates the characteristic of the comparative example in which the correction on the lower side of the target throttle opening is immediately canceled at the time t1 when switching to the power transmission state. . In the engine torque timing chart, the solid line characteristic represents the target engine torque tTQ, the alternate long and short dash line characteristic represents the upper limit value TQlim of the target engine torque, and the dotted line characteristic represents the target engine torque basic value TQ0.

During the period up to time t1 (t0-t1), the engine is in a stationary state where the vehicle speed is 0, the shift range operated by the shift lever is set to the N range, is in a non-power transmission state, and the accelerator pedal is depressed. You are in an empty state. In order to avoid overheating (overheating) of the exhaust system due to the continuation of the idling, the throttle opening is corrected to a lower side. Specifically, the target throttle opening tTVO is limited to a value TVOmin near the fully closed state. ing.

Then, in the driving state in which the throttle opening is reduced in this way, at time t1, the shift range by the shift lever is switched from the N range to the D range by the driver's operation, and the non-power The transmission state is switched to the power transmission state. At this time, if the correction to the decrease side of the throttle opening is immediately cancelled, the throttle opening increases rapidly, and the engine torque, that is, There is a risk that the vehicle driving torque will increase sharply and a torque shock will be given to the vehicle occupant causing the vehicle to start carelessly. On the other hand, in this embodiment, when canceling the correction to the lower side of the throttle opening, the throttle opening is gradually increased by gradually increasing the engine torque using the upper limit value TQlim. Since the correction to the lower side of the throttle opening is gradually released, the sudden increase in engine torque and vehicle drive torque can be prevented, and torque shocks that start the vehicle can be reliably reduced or eliminated. Can do.

In addition, since the target throttle opening is increased at a constant change speed while the correction is canceled, a smooth vehicle start without torque shock can be realized with a simple control configuration.

In such a situation where the throttle opening is gradually increased, when the upper limit value TQlim exceeds the engine torque basic value TQ0, the upper limit value TQlim is increased to the maximum value TQmax, and this upper limit value TQlim is used. After the restriction on the cancellation of correction to the decrease side of the throttle opening (engine torque) (processing for gradually increasing the throttle opening) is finished, the correction processing is immediately released. In this way, the correction cancellation process to the throttle opening decreasing side can be immediately terminated with a simple control configuration using the upper limit value TQlim.

As described above, the present invention has been described based on the specific embodiments. However, the present invention is not limited to the above-described embodiments, and includes various modifications and changes without departing from the spirit of the present invention. . For example, in the above-described embodiment, correction processing and correction cancellation processing for reducing the throttle opening is indirectly performed using the engine torque, but the value of the throttle opening is not used without using the engine torque. By directly limiting the above, correction processing and correction cancellation processing to the throttle opening decreasing side may be performed.

Claims

An accelerator opening detecting means for detecting an accelerator opening of an accelerator pedal operated by a driver;
A throttle which is provided in the intake passage of the engine and whose opening can be adjusted independently of the operation of the accelerator pedal;
Power transmission switching means capable of switching between a power transmission state capable of power transmission from the engine to the drive wheels and a non-power transmission state where power transmission is interrupted;
Throttle control means for controlling the throttle opening based on the accelerator opening;
Throttle opening correction means for correcting the throttle opening to the closed side when the accelerator pedal is depressed in a non-power transmission state while the vehicle is stopped;
When the throttle opening is corrected to the closed side by the throttle opening correcting means, when the power transmission switching means is switched from the non-power transmission state to the power transmission state, the throttle opening degree is closed. Throttle opening correction cancellation means for canceling the correction of
The throttle opening correction canceling means is an engine control device that gradually increases the throttle opening when canceling the correction of the throttle opening toward the closing side.
The throttle control means calculates a target engine torque based on the accelerator opening, calculates a target throttle opening based on the target engine torque, and controls the throttle opening toward the target throttle opening. ,
The engine control device according to claim 1, wherein the throttle opening correction canceling unit gradually increases an upper limit value of the target engine torque.
3. The engine control device according to claim 2, wherein the throttle opening correction canceling means increases the upper limit value of the target engine torque at a constant rate of change.
4. The engine control device according to claim 2, wherein the throttle opening correction canceling means immediately cancels the correction to the decrease side of the throttle opening when a predetermined condition is satisfied.
The engine control apparatus according to claim 4, wherein the predetermined condition is when the upper limit value of the target engine torque is larger than a basic value of the target engine torque obtained based on an accelerator opening.