DE10019742A1 - Deactivating fuel injection piston combustion engine cylinder(s) involves increasing rate of air feed to cylinders to reduce fuel component in air inlet channels while catalytic cleaning is active - Google Patents

Abstract

The invention relates to a method for decommissioning at least one cylinder of a piston internal combustion engine with electronic engine control, catalytic exhaust gas cleaning and fuel injection, which is characterized in that the fuel injection is switched off and the air supply to the cylinders is increased to break down the fuel wall film, while the catalytic exhaust gas cleaning remains activated.

Description

When a piston internal combustion engine is stopped, the mo Door operating switch opened and thereby the ignition and the fuel injection regardless of the particular Work cycle of the individual cylinders switched off. With that which inevitably cannot be neglected in the air supply tract sigant quantities of fuel in vapor and liquid form, especially in the form of a fuel film on the walls of the air intake ducts. This leads to a release of Hydrocarbons in the environment after the shutdown Piston engine by vaporizing this force remnants of fabric. When restarting, be it by ei Repeat start, be it with only temporary cylinder down circuit in operation under partial load, the wall film leads to increased hydrocarbon emissions when designing the amount of fuel to be supplied in the starting phase must be viewed.

The invention has for its object the above Problems due to a special guidance of the cargo movement to solve.

For a method for decommissioning at least one Zy linders a piston internal combustion engine with engine control, is catalytic exhaust gas cleaning and fuel injection provided according to the invention that the fuel injection switched off and to reduce the fuel in the Air intake ducts the air supply to the cylinders is increased and that the catalytic exhaust gas cleaning remains activated. This measure ensures that by switching off the Fuel injection and increasing air flow speed and the mass flow rate in the air inlet  let channels is increased and thus contained in the air supply tract Fuel shares, in particular a film of fuel to the Walls of the air intake ducts reinforced in the out of service to be taken cylinder.

There are two operating cases, namely the Au Shut down the cylinders for complete shutdown stood the piston internal combustion engine and temporarily out of order set individual cylinders for partial load operation of the Piston engine.

For the complete standstill, the ignition should start remain switched on, so that at least in part the cylinder according to the work cycle from the Air intake ducts fuel entered into the cylinder quantities in the remaining remaining work cycles in the Phase-out phase can be burned. As soon as no ignitable Mixture can be formed more, the low ones burned amounts of fuel are pushed out into the exhaust tract and can be implemented in the hot and active catalytic converter be, so that in total no or only small amounts of unburned hydrocarbons in the environment after Switch off the piston internal combustion engine. There the fuel wall film in the air intake channels practical is completely removed, the application effort for reduce fuel metering during a repeat start because an unintentional enrichment of the fuel-air Mixture due to residual fuel in the air intake ducts is reduced.

Who can be ensured by the existing motor control that after opening the engine operating switch, the Mo gate control independent of first the idling speed by predetermined amount increased after switching off the fuels injection the engine no longer delivers power and demented speaking the speed of a slightly increased speed ge sinks towards zero and so enough motorum after switching off  rotations before standstill to flush the air inlet channels are available.

In piston internal combustion engines with conventional, i.e. H. me mechanical actuation of the gas exchange valves and control of the Air supply via an adjustable throttle increases the Inflow velocity by fully opening a throttle flap in the air intake tract causes.

The method according to the invention is particularly useful in a throttle-free controlled piston internal combustion engine with camshaft adjustment or with fully variable control suitable gas exchange valves. When the pistons are formed Internal combustion engine with fully variable controllable gas exchange valves are each with their own valve train, for example in the form of electromagnetic actuators provided, each specified via the engine control programs and can therefore be controlled independently are, so that for example the valve opening and closing times, the opening time, the characteristics of the stroke etc. of the gas exchange valves in relation to the position of the cure can be controlled as desired. This is not only the case Stopping the piston internal combustion engine but also at only Temporary shutdown of individual cylinders under partial load operated through a targeted management of the cargo movement Pro control of the gas exchange valves to remove the fuel residue from the wall film.

In such a piston internal combustion engine with full varia The controllable gas exchange valves are used to dismantle the Charge wall for both modes of operation procedure set to "late intake opening". Hereby is downwards before opening the gas inlet valve a negative pressure in the combustion chamber builds so that the flow velocity in the associated Air inlet duct increased when opening the gas inlet valve and not only small amounts of fuel present in vapor form  but also the fuel wall film reinforced by the Walls of the air intake channels removed and in the resp towards the combustion chamber.

As far as the combustion chamber at least in the first phase after Switching off fuel injection in this way receives a combustible mixture, it is used for stopping ses at least partially implemented and then as Exhaust after opening the gas outlet valve in the exhaust duct pushed out and implemented in the still hot catalytic converter. To generate an ignitable mixture, you can on the amount of fuel wall film removed, the empi The amount of fresh air is known in the order of magnitude be influenced in a targeted manner in the cylinder. A no longer ignitable air-fuel mixture is at a complete Shutdown also supplied to the catalytic converter and around set.

With multi-cylinder piston internal combustion engines, the va riable control of the gas exchange valves also a part load drove in such a way that some of the cylinders were out of order is set so that the required load remains from the the, still fired cylinders must be applied. This Cylinders are then practically below in the upper load range fired most favorable operating conditions, overall there are but the piston internal combustion engine only a partial load. Also with this cylinder deactivation and reactivation is ins special care to ensure that no unburned fuel gets into the exhaust system to adversely affect avoid regulation of catalytic exhaust gas cleaning. Likewise, no air may be pumped through the cylinders, because this would lead to cooling on the one hand and on the other again disadvantageously via a change in the lambda value the regulation of the catalytic converter would act. Through the Control of the gas exchange valves according to the invention in the cylinders temporarily put out of operation by "late Inlet opening "is about the increased flow rate  the fuel wall film in the intake port is broken down. The dismantling of the Fuel wall film can also be caused by the Gas exhaust valves driven to "early exhaust closing" and that when you subsequently open the gas inlet valve due to the overpressure in the cylinder, hot exhaust gas initially enters the Inlet channel is guided, which supports the wall film degradation and with the then higher flow rate in the cylinder to a significant reduction in the amount of fuel accumulated in the channel walls. This Activation takes place in the last or in the last work play before the temporary shutdown.

If the cylinder is to be switched on again, then the The amount of fuel to be injected depends on the operating state and be increased by the switch-off time to one again Build up wall film so as to lean the burn Avoid air ratio when switching on. This more amount of fuel is added after the first work cycles adapted to switching on the cylinder.

Since the amount of wall film removed depends on the flow speed of the air in the inlet duct and this like which is dependent on the time of opening of the gas inlet valve tils, the amount of wall film taken off can be determined empirically Record values with sufficient accuracy. But that's also the Possibility given instead of an increase in fuel spray quantity when restarting the relevant Zy linders in the last work cycle before decommissioning of the cylinder according to the specified adjustment of the Gas inlet valve opening time, fuel injection quantity for the last work cycle already corresponds to the in about to reduce the amount of fuel removed from the wall ren, so that for the subsequent unfired phase of the be hitting cylinder in the cylinder practically no force Amounts of substance are entered so that during the unbe fired operating phase the gas exchange valves so operated can that also on other operating parameters, such as  for example a rotational irregularity, taken into account can be.

The variable valve train enables the shutdown of the Fuel injection, possibly also switching off the ignition a valve shutdown in the overrun phase. Either with valve shutdown in the overrun phase as well as with egg ner valve shutdown for decommissioning in partial load driven, the shutdown for any number of cure revolutions of the shaft are carried out. Switching on the Cylinder does not necessarily have to be in the usual 4-stroke process common after a full working cycle with two engine revolutions gene take place, but it is also a control example wise in the 2-stroke process and then transitioning to the 4-stroke Procedure possible. For both procedures, it is for the not fired operating phase possible, in addition to the shutdown of all gas exchange valves of a cylinder either only completely the gas inlet valves or only completely the gas outlet valves switch off. The choice of method influences the Wall film breakdown so that this is at the required fuel quantity correction are taken into account when switching on again got to.

When the gas inlet valves are shut down and when complete shutdown of all valves must the fuel reduced for the first or for the first work cycles because during the shutdown phase due to the operation temperatures in the gas inlet channel a further fuel vaporization of the stored fuel takes place. For the fol The working quantity must then be the same as before mentioned above, increased by the operating state to rebuild dependent wall film. In contrast, the Switching off the gas outlet valves increases the force amount of substance in the first working games after switching on must be done again.  

If the gas inlet valves are switched off, a appropriate choice of the exhaust tax times are avoided, that a negative pressure develops in the cylinder and thus burns Gases and oil from the crankcase into the combustion chamber long. The time "outlet closes" is in the loading range of bottom dead center before the high pressure phase or after the bottom dead center before the high pressure phase. The opening and The gas outlet valve closes in the area of the vice exercise pressure condition, d. H. in the area of the exhaust gas pressure in the Ab gastrointestinal tract. This is the case when the gas outlet valves are closed ren also transferable to the gas inlet side.

The first work cycle with the cylinders switched off can both cases either after pushing out the cylinder dung or after the intake of fresh air, where in the process without drawing in fresh air due to the lower temperature decrease is preferable. When again switching of the cylinder, except when switched off with closed Senem gas outlet valves and active gas inlet valves, must the complete amount of charge from the work cycle before Shutdown comes, pushed out before the first suction become. This is controlled by a "outlet closes" in the Top dead center reached.

Were all gas exchange valves de when switching off the cylinders activated, the gas outlet valve in the Be range of ambient pressure after bottom dead center in the Extension phase are opened to suck in exhaust gas from the outlet duct and a flushing out of oil and power to avoid material residues in the cylinder. The gas outlet valve must be opened so as to open the gas inlet valve To avoid overpressure. Compensation through "late on "let open" is possible. This means that over not fully sealed valves and piston rings sucked in air ejected together with the oil and fuel components the. A filling of the cylinder with air during the ab switching phase is avoided if by appropriate  Valve timing the build-up of negative pressure in the cylinder ver is avoided.

When the gas outlet valves are switched off and when the gas is active inlet valves, the gas outlet valves are switched on after the first burn. The required load is about the valve timing "inlet closes" is set, preferably wise with the load control method "early intake closing".

By activating "late intake opening" the stabilizer increases combustion and thus the residual gas compatibility. Through this charge exchange control when the Cylinder will have greater starting safety if not full Residual gas quantities continuously postponed after the shutdown phase achieved.

In a further embodiment of the invention it is provided that the gas outlet valves are driven to "early outlet closing" become. As a result, a corresponding, preferably ge amount of hot exhaust gases at the end of the push out phase in Combustion chamber held back and by the upward movement of the Piston compressed. When opening the inlet valve in In the area of top dead center, this amount of exhaust gas flows with it at high speed in the air intake duct. Through the Flow rate of the gases and the heating of the Air inlet duct through the still hot exhaust gases takes place significant reduction in the amount of wall film. Those in the gas Abkanal pushed out and loaded with fuel vapor Ab The amount of gas can be combined with the gas inlet valve still open be sucked back into the combustion chamber with fresh air. After closing the gas inlet valve, an ignitable Mixture can then be ignited. The exhaust gas or unburned tes mixture is in the gas after opening the gas outlet valve exhaust channel pushed out so that when the Piston engine implementing the gas inlet channel deducted amounts of fuel in the still hot catalyst can be done.  

Since the gas inlet valves are fully variable, be there is also the option of pushing out the hot ones Exhaust gases in the intake duct, the intake valve briefly too close and only again in the position "late inlet NEN "so that the contained in the gas inlet channel, ejected hot exhaust gas provided with fuel vapor quantities in turn in the distillery at a very high speed be sucked back.

To better rinse out the fuel wall film will continue proposed to increase the amount of charge. This can be about opening the throttle valve or by adjusting the Valve timing "inlet closes" take place, both also Measures are possible.

To compensate for those occurring during the switch-off phase additional load from the afterburning of the fuel wall film, for example, the valve timing "outlet opens "can be varied.

Because not only the crankshaft speed for the engine control but also via an appropriate sensor system in operation respective position of the crankshaft can now be detected the valve trains are deactivated when the crankshaft is at a standstill become. For gas exchange valves with electromagnetic actuation valve drives, this is done by switching off the loading flow of the electromagnets of the actuators.

When stopping the piston internal combustion engine can currently point of switching off the current supply assumes who that almost all gas exchange valves from the respective catcher Magnets in a fully open or a closed one Position held at this time. With the same Switching off the current early causes all gas changes to oscillate valves each from their caught end position in the direction to the other end position beyond the middle position, without  to reach this, however, and again via the middle layer until the rest position in the Mit after swinging out tellage has been reached.

Here a clearly audible, disturbing noise occurs, because the electromagnetic designed as a spring-mass system Actuators over a period of several tenths of a second continue to vibrate in a decaying vibration. Thereby becomes clear in the air intake system and in the exhaust system audible gas vibration excited.

In order to avoid this disadvantage, is in a fiction moderate method, in particular in connection with the existing process for flushing out residual fuels it is proposed that the current supply to the individual electromagnetic valve trains in a predeterminable series sequence is switched off after the fuel supply is switched off has been switched.

If the Be current of the actuators not switched off at the same time, son scarfed one after the other in a predetermined order tet, then the structure of such a gas vibration in Air inlet duct and in the gas outlet duct and thus the first Avoid annoying noise.

In one embodiment of the method according to the invention it is possible in a preliminary step to switch off the electro magnetic valve train of the gas exchange valves the gas let valves and the gas outlet valves per working cycle to be actuated in the open position. This will then either when opening or when closing the corresponding catch current switched off on the catch magnet, so that the actuators all swing out one after the other.

With a motor control with a failure detection for the Electromagnetic valve trains must be used in this procedure  the automatic swing-out function of the failure detectors be deactivated to ensure that in the off oscillation phase, the valve trains are not automatically restarted be swinging.

The invention is based on schematic drawings he purifies. Show it:

Fig. 1 is a block diagram of a Kolbenbrennkraftmaschi ne with control,

Fig. 2 is a diagram charge exchange "late inlet opening",

Fig. 3 shows a charge cycle diagram "late Auslaßschlie KISSING"

Fig. 4 is a gas exchange diagram with exhaust gas intake.

In Fig. 1 for a multi-cylinder piston internal combustion engine ne only a cylinder 1 is shown schematically, in which a piston 3 connected to a crankshaft 2 is guided movably up and down in a conventional manner. The combustion chamber 4 delimited by the cylinder 1 and the piston 3 is provided with an air inlet duct 5 and a gas outlet duct 6 , the gas outlet duct 6 being connected to a catalytic exhaust gas purification 7 . A controllable fuel injection nozzle 8 opens into the air inlet duct 5 . In the air intake duct 5 , a controllable throttle valve can also be arranged, in particular with an adjustable camshaft control.

At least one gas inlet valve 9 is assigned to the air inlet channel 5 and at least one gas outlet valve 10 is assigned to the gas outlet channel 6 . The gas inlet valve 9 and the gas outlet valve 10 , hereinafter referred to as gas exchange valves, are each connected to a fully variably controllable valve train 11 , which is designed here as an electromagnetic valve train. The gas outlet valves 10 can optionally be actuated via a camshaft.

The electromagnetic valve drive 11 is essentially formed by a closing magnet 12 and an opening magnet 13 arranged at a distance therefrom, between which, against the force of return springs, not shown here, an armature 14 connected to the gas exchange valve 9 or 10 with alternating energization of the closing magnet and the Open nermagneten is movable back and forth. When de-energized Elek tromageneten the armature 5 assumes an equilibrium position in the middle position between the two electromagnets due to the mutually ge directed effect of the two return springs.

The fuel injection 8 , the spark plug only indicated here and the electromagnetic valve drives 11 are controlled by an electronic engine control 15 , which detects both the speed of the crankshaft and the crank position for controlling the gas exchange valves 9 , 10 via a corresponding encoder 16 . The desired load is specified via the position of an accelerator pedal 17 of the engine control 15 .

The motor controller 15 can be activated in a conventional manner via a key switch 18, which switches over the key 18 control in a conventional manner after activating the motor, the starter is not shown in detail here can be switched to.

The engine control 15 is provided for the implementation of the shutdown procedure with a schematically illustrated switch-off logic 19 , which is designed so that after the adjustment of the key switch 18 to the "off" position, a switch-off program runs itself.

Through the switch-off program by a corresponding control of the gas exchange valves 9 , 10 after switching off the fuel injection, the amounts of fuel contained in the gas inlet channel 5 as fuel wall film and also as fuel vapor are fed to the catalyst 7 for final implementation via the combustion chamber 4 via the exhaust channel 6 .

Due to the switch-off logic 19 specified in the switch-off logic 19, the idle speed may be increased by a small amount after reaching the "off" position of the key switch 18 . Then the fuel injection 8 is switched off in the normal working cycle of the piston internal combustion engine and the gas inlet valves 9 are driven to remove the fuel wall film on "late inlet opening", so that air is sucked in from the gas inlet channels 5 to the individual cylinders at high flow velocity, the speed of sound becomes. After the respective closing of the gas inlet valves 9 , the fuel from the fuel wall film is burned as far as possible or the fuel is pushed out of the combustion chamber 4 after the gas outlet valves 10 have been opened in accordance with the working cycle of the piston internal combustion engine into the gas outlet channel 6 and fed to the catalyst 7 . By choosing the control times for the gas inlet valves and the gas outlet valves, the additional load can be compensated in the additional work cycle.

In the phase-out phase, the current supply to the individual electromagnetic valve drives 11 can be switched off at a predeterminable low speed, so that not all gas exchange valves can swing out into their rest position at the same time but only one after the other. This avoids the annoying noise that occurs when all gas exchange valves are stopped at the same time.

In addition or as an alternative to the above-described control of the gas inlet valves with "late inlet opening", the gas outlet valves 10 can be controlled with "early outlet closing" via the engine control unit 15 , so that a correspondingly hot exhaust gas quantity from the combustion chamber into the gas outlet valve 9 is already open Gas inlet channel 5 is pushed out, so that the gas inlet channel experiences a temperature increase in each case through the still hot exhaust gases and so, in addition to the high flow velocity of the flushed fuel, vaporize film and is sucked into the combustion chamber 4 during the piston downward movement and burned or closed after the gas inlet valve 9 is closed Opening the gas outlet valve 10 can be pushed into the gas outlet channel 6 .

In a piston internal combustion engine with mechanically, for example practically rigidly controlled, actuated gas exchange valves via camshafts, the fuel injection, ignition, etc. is actuated via a correspondingly designed engine controller 15 . Instead of a load-dependent change of the opening times of the gas inlet valves and the gas outlet valves in accordance with a predetermined load request, in addition to a change in the fuel injection quantity, a change in the air supply quantity takes place in a known manner via a correspondingly controllable throttle valve in such a piston internal combustion engine. Since with such a piston internal combustion engine an influencing of the Ventilöffnungszei th is not possible, here in the context of the "switch-off program" after the position of the key switch in the "off" position via the switch-off program in the manner described above, the idling speed may automatically be slight increased, then switched off the fuel injection and opened the throttle valve in the air intake tract, so that in normal operation the fuel contained in the air intake ducts are sucked in and pushed out into the exhaust tract. The ignition can be switched off at a corresponding time for fuel injection, so that all of the combustible cylinder fillings are at least partially burned.

Fig. 2, 3 and 4 show, depending on the pressure in relation to the piston movement from top dead center OT to bottom dead center UT and back to top dead center, that is over ei ne full crankshaft rotation, the course of the gas exchange for different actuation times of the gas exchange valves. The circulation takes place in the direction of the arrows. AÖ stands for "let off opens", AS stands for "outlet closes", EÖ stands for "inlet opens" and ES stands for "inlet closes". From these sen the above described different controls of the gas exchange valves can be read.

Claims (12)

1. A method for decommissioning at least one Zylin a piston internal combustion engine with electronic motor control, catalytic emission control and fuel injection, characterized in that the fuel injection is switched off and the air supply to the cylinders is increased to reduce the fuel content in the air inlet channels and that the catalytic emission control in the air inlet ducts remains activated. 2. The method according to claim 1, characterized in that the Decommissioning for the purpose of stopping the pistons Internal combustion engine takes place and the catalytic exhaust gas purification supply until the piston internal combustion engine stops fourth remains. 3. The method according to claim 1, characterized in that the Decommissioning individual cylinders for the purpose of a part load operation with further firing of the other cylinders he follows. 4. The method according to claim 1 or 2, characterized in that before the fuel injection is switched off, the empty running speed is initially increased. 5. The method according to any one of claims 1 to 4, characterized ge indicates that a throttle to increase the air supply flap is adjusted in the air intake. 6. The method according to any one of claims 1 to 5, characterized ge indicates that the valve control increases the air supply get the gas inlet valves to "late inlet closing" ver is posed.   7. The method according to any one of claims 1 to 6, characterized ge indicates that the gas exchange valves from the 4-stroke process can be switched to 2-stroke processes.   8. The method, in particular according to claims 1 to 7, for Application to a piston internal combustion engine in which the Actuate gas exchange valves via electromagnetic valve drives be activated, which can be controlled via the motor control Have opening magnets and closing magnets that on a act on the armature connected to the respective valve, because characterized in that the energization of individual elektroma Magnetic valve train on selected or all cylinders switched off and / or switched on in a predefinable manner after the fuel supply to the cylinder for a predeterminable number of work cycles has been switched off. 9. The method according to claim 8, characterized in that at a piston internal combustion engine with more than two gas changes valves per cylinder in a preliminary step to switch off the Gas exchange valves, the gas inlet valves and the gas outlet valves tile alternating from work cycle to work cycle actuated and the opening magnets and closing magnets each Weil are controlled so that the gas exchange valves each because it is no longer fully open and not completely closed become. 10. The method according to claim 8 or 9, characterized in that in the engine control an automatic start function failure detection for the electromagnetic valve drives is deactivated. 11. The method according to any one of claims 1 to 10, characterized ge indicates that the gas inlet valves and the gas outlet valves tile can be driven to "late inlet opens". 12. The method according to any one of claims 1 to 1, characterized ge indicates that the gas inlet valves and the gas outlet valves Tile can be controlled to "early exhaust closing".