DE102007009857B4 - Motor control for controlling an automatic shutdown of a direct injection internal combustion engine - Google Patents

Abstract

Engine control for controlling an automatic shutdown of an internal combustion engine with direct injection, wherein the engine control by appropriate shutdown automatically shuts off the engine when all predetermined shutdown conditions are met, characterized in that the Abschaltmaßnahmen be divided into preparatory shutdown and remaining Abschaltmaßnahmen and the engine control upon detection of a driver stop request Such preparatory shut-off action is to reduce the intake pipe pressure (Ps) existing in a suction pipe.

Description

The The invention relates to a motor controller for controlling a automatic shutdown of an internal combustion engine with direct injection according to the preamble of claim 1.

Around To reduce fuel consumption and pollutant emissions currently processes and systems are developed and partly already used, which the internal combustion engine of a motor vehicle under certain conditions or in the presence of predetermined shutdown automatically switch off and automatically in the presence of predetermined connection conditions turn on again. Such methods and systems are above all else for the City traffic suitable for reducing fuel consumption, because in city traffic the vehicle often at traffic lights or due to the Traffic comes to a halt and the operation of the internal combustion engine is not required.

So is out of the DE 101 61 343 A1 an automatic stop and start control device for an internal combustion engine is known, wherein the control device performs appropriate measures for switching off the internal combustion engine, when all said shutdown conditions are met. For example, the speed of the vehicle must be below a predetermined threshold, an idle switch must be on, and a gearshift position of the transmission must be in neutral. According to the disclosure of DE 10 2004 024 212 A1 If the vehicle speed is greater than zero, the internal combustion engine is automatically switched off by appropriate shutdown measures, and at the same time the clutch is open or the vehicle transmission is in the neutral position.

Furthermore, the DE 601 14 702 T2 A1 an engine controller for controlling an automatic shutdown of a direct injection internal combustion engine, which automatically shuts off the engine by appropriate Abschaltmaßnahmen when all stop conditions are met. In particular, during a period of time prior to performing the automatic shutdown, an increase in fuel pressure is made to one side of the fuel injection valve.

The Known methods and systems all have in common that the automatic Shutdown or the measures for automatic shutdown of the internal combustion engine only initiated when all the specified switch-off conditions have been met. Thus, it takes a relatively long time until the internal combustion engine is switched off is. In certain circumstances It can also happen that due to the prevailing in the intake manifold Pressure at the time of automatic shutdown of the internal combustion engine Vibrations occur and thus it is a short-term uneven running the internal combustion engine comes. This vibration mainly occurs enthrottled combustion process, for. B. in direct injection systems on. Both the long duration until the internal combustion engine finally switched off is, as well as the possibly occurring "shaking" of the internal combustion engine act focus on the driver in terms of the comfort of this automatic Shutdown system negative.

task The invention is thus an engine control system for internal combustion engines specify with direct injection, in which the vibrations of the internal combustion engine while prevents an automatic shutdown of the internal combustion engine or at least be able to be reduced.

These Task is solved by a motor control according to claim 1. advantageous Further developments emerge from the dependent claims.

Of the Invention is based on the finding that the vibrations during automatic shutdown of the internal combustion engine by a too high Intake manifold pressure caused. Would a Redzierung the intake manifold pressure be made only if all predetermined shutdown conditions to initiate an automatic shutdown, the Time until switching off the internal combustion engine by switching off fuel injection or ignition is insufficient to to provide the necessary low intake manifold pressure. Would the Motor control after the presence of all shutdown conditions only one Reduce intake manifold pressure and only if necessary low intake manifold pressure is reached, stop the injection and / or the ignition stop, would It will take a long time for the internal combustion engine to shut down completely is.

The engine control according to the invention for controlling an automatic shutdown of an internal combustion engine with direct injection is characterized in that the shutdown measures in preparatory shutdown measures and remaining shutdown measures are divided and preparatory measures are made before the presence of all shutdown conditions, and then when the driver stop request is recognizable , The engine control then takes such a preparatory shutdown measure upon detection of the driver stop request that the intake manifold pressure present in a suction pipe is reduced. The intake manifold pressure is reduced until a predetermined negative pressure in the intake manifold established.

is The motor vehicle, for example, with a hybrid drive unit from an internal combustion engine and an electric motor for driving the Motor vehicle equipped, in certain situations, too the engine is switched off and the vehicle only with the Electric motor operated. A division into preparatory shutdown measures and remaining shutdown measures, as they are the subject of the invention can also in such Shutdown of the internal combustion engine are made. The named Driver stop request corresponds to an operational stop request of the hybrid system.

advantageously, the intake manifold pressure is reduced by the fact that the engine control engages in the operation of the internal combustion engine such that a at the time of detecting the driver stop request in shift operation operated internal combustion engine is switched to the homogeneous mode and that a throttle valve present in the intake pipe is activated in this way will reduce the air flow in the intake manifold.

at Internal combustion engine with direct injection is in a homogeneous operation the fuel during of the intake stroke, and in a shift operation, the fuel during the Compression clocks injected into the combustion chamber of the internal combustion engine. Of the Homogenous operation is preferably for the full-load operation of the internal combustion engine provided while the shift operation for idle and part load operation is suitable. In general, can be assumed that the internal combustion engine at Recognition of the driver stop request is in homogeneous operation. Under certain circumstances However, it can also happen that the internal combustion engine when detecting the driver stop request is in shift operation. Will now in recognizing the driver stop request in the homogeneous mode switched, reduces the intake manifold pressure present in the intake manifold.

is If the internal combustion engine is already in homogeneous operation, the Intake manifold pressure thereby further reduces that the throttle so changed in their position is that less air is fed into the intake manifold. Such Actuation of the throttle valve can also be used in combination with the changeover from shift operation to homogeneous operation.

In addition, still can further preparatory shutdown initiated by the engine control become. Thus, the engine control can be detected when the driver stops additionally make such preparatory shutdown measures that lead to that an existing in the motor vehicle exhaust gas recirculation valve is closed and / or that a variable camshaft adjusting device present in the motor vehicle is brought into its final position and / or that in a fuel supply pipe present fuel pressure for later Start increased is and / or that due to active ancillaries ancillary load is reduced. By reducing the accessory load becomes the required Torque reduced. As a result, the amount of air to be sucked can be reduced become.

Has the intake manifold pressure reaches a predetermined first vacuum threshold or undershot and / or was a predetermined first time interval from Time of recognition of the driver stop request exceeded and / or was the internal combustion engine at the time of detecting the driver stop request in homogeneous operation and has the relative filling in the suction system, so the Air mass in the suction system reaches a predetermined filling limit falls below, sends the engine control in an advantageous Embodiment of the invention from an acknowledgment signal to show that from the side of the internal combustion engine an automatic shutdown nothing stands in the way. Are all other shutdown conditions fulfilled and is a driver's termination of the automatic shutdown process not possible anymore, The motor control initiates the remaining shutdown measures automatic shutdown of the internal combustion engine.

The remaining shutdown measures can in first remaining shutdown measures and second remaining shutdown measures be split, which are initiated at a staggered time. advantageously, the engine controller takes such first remaining shutdown actions that an existing throttle is completely closed and / or that the ignition point an existing ignition system after late is adjusted and / or that a deactivated generator again is activated. Through the whole Shut down the throttle valve, the intake manifold pressure can now to an absolute minimum be lowered, whereby the vibrations are additionally attenuated in the outlet can and Z. B. a noise can be avoided by a swinging dual mass flywheel. By the ignition angle adjustment after late and the connection of the generator will be less combustion moment generates, whereby the internal combustion engine faster completely is.

If the driver stop request is recognizable or if a predetermined second time interval has elapsed after the initiation of the remaining shutdown measures, the engine control in an advantageous embodiment of the invention during the phase out of the engine still start preparatory actions. This allows a much faster start in the presence of all Anschaltbedingungen be enabled. In some cases, the start-up measures can already be made when the driver stop request is detected. Such a measure would be, for example, the increase of the fuel pressure. In principle, start-up measures can be undertaken within a time window which begins at the time when the driver stop request is detected and ends at the time when the internal combustion engine is switched off.

These it is the shutdown to a systemic shutdown the internal combustion engine in a motor vehicle with a hybrid drive unit, can by means of electric drive of the internal combustion engine in an optimal Start position are stored.

advantageously, can the engine control system undertake such a start-up preparation, that a closed throttle is opened. This increases abruptly again the intake manifold pressure, so that when automatically turned on the internal combustion engine again ambient pressure prevails in the intake manifold. Corresponds to the pressure in the suction pipe again in about a predetermined third pressure threshold, which is identical to the ambient pressure, the throttle valve can be closed again. As another start-up measure can the fuel pressure in a fuel supply pipe can be increased.

If while the time from the initiation of the remaining shutdown measures to the initiation of the start preparation activities Start-up conditions or all connection conditions, must ensure the engine control that the throttle opens again, so that the necessary Intake manifold pressure for the automatic power-up can be provided.

The inventive method will now be based on an embodiment explained in more detail. there the only figure shows one over the time applied intake manifold pressure before and after an automatic Switching off a gasoline engine with direct injection, taking into account the Motor control according to the invention.

The Figure shows a over the time t applied intake manifold pressure Ps within a Saurohrs, by this is the air necessary for combustion in the respective cylinders is sucked. Pu is the ambient pressure that outside the equipped with the gasoline engine with direct injection motor vehicle prevails.

from The beginning of the time representation t0 is up to the time t1 the internal combustion engine due to current operating parameters in shift operation, d. H. the fuel gets during of the compression stroke injected into the combustion chamber of the internal combustion engine. In the suction pipe there is a pressure of Ps1, which is slightly lower, as the ambient pressure Pu. At time t1, the engine control unit receives due an input signal, the information that the driver a shutdown the internal combustion engine wishes. Then the engine control switches from shift operation to Homogenous operation of the internal combustion engine, which includes the exhaust gas recirculation valve, the part of an exhaust gas recirculation system for Control and / or rules of exhaust gas recirculation is and throttles Control of the throttle valve the air flow. By the change the operating mode of the internal combustion engine, the closing of the Exhaust gas recirculation valve and throttling, the pressure Ps in the suction pipe of Ps1 decreases at the time t1 up to a second intake manifold pressure Ps2 at time t2. Within In the period of t1 and t2, additional measures d_K are initiated to an increase lead the fuel pressure in the fuel supply pipe.

in the At time t2, the intake manifold pressure Ps has a predetermined first negative pressure threshold Ps2 reached. Then an acknowledgment signal is generated. From this Time t2 is also a driver-side cancellation of the automatic Switch-off process no longer possible. Furthermore, all other shutdown conditions are present. From this Time t2 closes the engine control completely the existing throttle in the intake manifold, so that the intake manifold pressure Ps is further reduced. In addition will turned off the injection and made an ignition retard, whereby an additional Vibration excitation by burning the already injected Fuel is prevented. This avoids unnecessary kinetic Energy is introduced into the system and thus the internal combustion engine comes to a standstill faster. Finally, the intake manifold pressure reaches a second negative pressure threshold PS3, which did not fall below can be.

By targeted individual injections and ignitions or deceleration through the generator, which made in this phase-out t2 to t4 be, the internal combustion engine can be made that She runs into a regulated parking area, so the next start optimally executed can be. Targeted parking can be used for quick start operations can be used up to the direct start.

In a given by a time interval time t4 are prepared by the engine control startup measures. These are designed such that the closed throttle valve is fully opened again to have at start of the engine again ambient pressure Pu in the intake manifold. As soon as the pressure Ps in the intake manifold has reached a predetermined third pressure threshold, ie ambient pressure Pu, the throttle valve is closed again. As a start-up preparatory measure, a fuel pressure present in a fuel supply pipe can also be increased when the driver stops to be detected, that is to say from time t1 onward.

By this division of the shutdown measures in preparatory shutdown measures and remaining shutdown measures, which made only when all shutdown conditions can be and the change of the invention The intake manifold pressure is much faster and more comfortable automatic shutdown of the engine and a larger fuel and Emission savings potential possible.

Claims (11)

Engine control for controlling an automatic shutdown of an internal combustion engine with direct injection, wherein the engine control by appropriate shutdown automatically shuts off the engine when all predetermined shutdown conditions are met, characterized in that the Abschaltmaßnahmen be divided into preparatory shutdown and remaining Abschaltmaßnahmen and the engine control upon detection of a driver stop request Such preparatory shut-off action is to reduce the intake pipe pressure (Ps) existing in a suction pipe. Motor control according to Claim 1, characterized that the intake manifold pressure (Ps) is reduced by a Time of recognition of the driver stop request operated in shift operation Internal combustion engine is switched to homogeneous operation and that an existing in the intake manifold throttle is controlled such that the air flow in the intake manifold is reduced. Motor control according to Claim 1 or 2, characterized that the engine control Derar term when detected driver stop request preparatory shutdown measures makes that an existing in the motor vehicle exhaust gas recirculation valve closed and / or that a variable camshaft adjusting device present in the motor vehicle is brought into its final position and / or the one in a fuel supply pipe present fuel pressure increased is (d_K) and / or that due to active ancillaries existing Ancillaries load is reduced. Motor control according to one of the preceding claims, characterized characterized in that the remaining shutdown measures are carried out, if an intake manifold pressure (Ps) present in the intake manifold is a predetermined first vacuum threshold (Ps2) has reached or fallen below and / or if a predetermined first time interval from the time of recognition exceeded the driver stop request was and / or when the internal combustion engine at the time of Detecting the driver stop request was in homogeneous operation. Motor control according to Claim 4, characterized that the engine control such first remaining shutdown measures makes an existing throttle valve is closed and / or that the ignition timing an existing ignition system after late is adjusted and / or that an existing and deactivated generator is activated. Motor control according to claim 4 or 5, characterized that the engine controller such second remaining Abschaltmaßnahmen makes a fuel injection stop and / or the ignition is switched off when a present in the intake manifold intake manifold pressure (Ps) has reached a predetermined second negative pressure threshold (Ps3). Motor control according to one of the preceding claims, characterized characterized in that the motor control within a time window, that at the time (t1), from which the driver stop request is detected, starts, and at the time when the internal combustion engine is switched off is (t3), ends, performs start-up action. Motor controller according to Claim 7, characterized that the engine control is recognized as ready to start when the driver is stopped measure a fuel pressure present in a fuel supply pipe elevated. Motor control according to Claim 7 or 8, characterized that the engine control in a motor vehicle with a hybrid Drive unit during a shutdown of the internal combustion engine as a start-up measure the internal combustion engine in a predetermined crankshaft angle position stores. Motor control according to one of claims 7 to 9, characterized in that the engine control such start preparing activities makes a closed throttle valve open and / or a present in a fuel supply pipe fuel pressure elevated becomes. Motor controller according to claim 10, characterized characterized in that the opened throttle valve is closed again when the intake manifold pressure (Ps) has reached a predetermined third pressure threshold (Pu).