DE10220076B4 - Method and device for controlling an internal combustion engine - Google Patents

Abstract

Method for controlling an internal combustion engine (1) with pulse charging (26) and fuel injection (5) in a charge exchange channel (30), wherein the pulse charging (26) is driven, characterized in that the injection duration depends on the activation of the pulse charging (26) is set.

Description

State of the art

The invention is based on a method and a device for controlling an internal combustion engine according to the preamble of the independent claims.

From the DE 199 08 435 A1 A method for impulse charging of a reciprocating internal combustion engine is already known in which the cross section available for flow in a charge exchange channel can be closed by means of a component when the charge exchange valve is open and the piston is in an intake stroke. The movement of the component into its position releasing the cross-section is effected by the negative pressure forming downstream of the component and the flow entering the cylinder with increasing opening of the charge exchange valve. The component is designed as a flap which is resiliently biased in the closing direction and forms a magnet armature, which rests in the closed position on a charge exchange valve facing the pole face of an electromagnet. It is provided an electronic control device for driving and current loading of the magnetic coils. The method can be used for all types of engines, whether they are multi-cylinder intake and exhaust valves, petrol or diesel engines, naturally aspirated or supercharged, single or multi-cylinder, and so on.

From the EP 0 547 566 A1 For example, there is known a method for supplying air into the combustion chamber of a piston-type internal combustion engine in two phases. In this case, the air supply is divided into the combustion chamber in two phases, wherein at least towards the end of the first phase, the air supply to the combustion chamber is obstructed and wherein at least at the beginning of the second phase, which ends with the incipient compression of the charge by the piston associated with the combustion chamber, the obstruction of the air supply is lifted. The Aumass of disability, the onset of disability, the end of the disability and the end of the air supply is coordinated so that the resulting Lolbenarbeit required for filling the combustion chamber with the desired amount of air Förderarbeitzuzu to a case else desired increase in temperature in the combustion chamber required energy corresponds.

From the DE 197 54 287 A1 is an internal combustion engine with at least one cylinder with at least one leading into the cylinder intake duct with a controllable inlet cross-section known, wherein in the intake passage at least one inlet cross-section controlling valve is provided. It is provided that the at least one valve is associated with at least one controlled as a function of a duty cycle of the internal combustion engine ballast valve.

Advantages of the invention

The object of the invention is to provide a method and a device for controlling an internal combustion engine having the features of the preamble of the independent claims, with which the treatment of the air-fuel mixture can be improved and a reduction of pollutant raw emissions can be achieved. The object is solved by the features of the independent claims. Advantageous developments of the invention are described in the subclaims.

The inventive method and the inventive device for controlling an internal combustion engine with the features of the independent claims have the advantage that the injection duration is set depending on the control of the pulse charging. In this way, the treatment of the fuel-air mixture can be improved and the reduction of pollutant raw emissions achieved. The injection duration is also referred to as injection time in the description.

The measures listed in the dependent claims advantageous refinements and improvements of the main claim method are possible.

It is particularly advantageous if the activation of the pulse charging comprises a control of a component for opening and closing a flow cross-section of the charge exchange channel and the injection time is set as a function of the activation of the component. In this way, a particularly simple relationship between the setting of the injection time and the control of the pulse charging can be produced, which is purely time-dependent.

This can be realized particularly simply by setting the start of injection as a function of an opening time of the flow cross section.

It is particularly advantageous if an application of the start of injection is carried out as a function of the opening time of the flow cross section as a function of at least one parameter of the internal combustion engine, in particular of exhaust gas emission values. In this way, an optimization of the injection time with respect to the at least one parameter of Achieve internal combustion engine and achieve, for example, a minimization of pollutant raw emissions.

It is particularly advantageous if the injection time is set as a function of the flow rate influenced by the impulse charging in the charge exchange channel. In this way, the speed at which the fuel enters the combustion chamber can also be influenced. In addition, this can affect the consistency of the fuel and thus the combustion and the tendency to knock.

It is particularly advantageous if the fuel is injected at the time of the highest flow velocity. In this case, the fuel reaches the combustion chamber fastest. As a result, the fuel in the combustion chamber has more time for evaporation, whereby a cooling effect is achieved and the tendency to knock is reduced. Due to the high flow velocity, the injected fuel will result in a smaller droplet size, so that the fuel burns better.

It is also advantageous if the injection time is set as a function of a pressure measured in the charge exchange channel. This also represents an easy way to set the injection time depending on the control of the pulse charging.

drawing

An embodiment of the invention is illustrated in the drawing and explained in more detail in the following description. Show it

1 a block diagram of an internal combustion engine with pulse charging and fuel injection in a charge exchange channel,

2 a block diagram of a device according to the invention for controlling the internal combustion engine,

3 a schematic representation of the operation of the pulse charging and

4 a pulse timetable to illustrate the method according to the invention.

Description of the embodiment

In 1 features 1 an internal combustion engine, the multiple cylinders 2 has, in each of which a piston 4 working, who has a connecting rod 6 with a crankshaft 8th connected is. The fresh air supply to the respective cylinder 2 takes place through an air filter 10 through, via a connecting cable 12 with an air collector 14 is connected, from which individual swing tubes 16 in the combustion chamber 18 the cylinder 2 to lead. According to the invention, the vibration tube 16 with a total of 26 designated device for impulse charging provided. The part of the vibration tube 16 between the device 26 for impulse charging and the combustion chamber 18 is hereinafter referred to as a charge exchange channel 30 or suction tube called. In the mouth of the suction pipe 30 in the combustion chamber 18 is an inlet valve 20 arranged. In the opening of the combustion chamber 18 in an exhaust duct 22 inside is an exhaust valve 24 arranged.

The modes of operation of such internal combustion engines, including the fuel-air mixture preparation, etc., are known per se and will therefore not be explained in detail. In the illustrated embodiment of the intake system, the length of the swing tubes is 16 specifically tuned to a specific speed range in which a particularly good filling is achieved. The length of the swing tubes 16 can be changed or switched by suitable Saugrohrgestaltung.

In 1 is also a device 50 for controlling the internal combustion engine 1 represented, which is also referred to below as the control unit. The control unit 50 serves to control the device 26 for impulse charging. Furthermore, according to 1 a device 5 for fuel injection into the charge exchange channel 30 provided also by the control unit 50 is controlled. Optional and in 1 shown in dashed lines in the charge exchange channel 30 a pressure sensor 55 and / or a flow rate sensor 60 be provided, each with the control unit 50 are connected. In the outlet channel 22 Optionally an exhaust gas sensor 65 be provided, which also with the control unit 50 connected is.

In 2 is the control unit 50 shown in more detail. It includes funds 45 for controlling the device 5 for fuel injection. It still includes funds 70 to Control of the device 26 for impulse charging. It optionally further includes funds 75 for receiving an intake manifold pressure value from the pressure sensor 55 , It also includes optional funds 80 for receiving a flow rate value from the flow rate sensor 60 , It also includes optional funds 85 for receiving an exhaust emission value from the exhaust gas sensor 65 , The means 70 . 75 . 80 . 85 are with the means 45 connected.

As in 2 indicated, includes the device 26 for impulse charging a component 35 for opening and closing a flow cross-section 40 of the charge exchange channel 30 , as in 3 shown schematically. In 3 In this case, the same reference numerals denote the same elements as in the preceding 1 and 2 , The control of the device 26 for impulse charging by the means 70 takes place according to 3 by controlling the component 35 or the control of the opening time of the flow cross-section 40 and the closing time of the flow cross section 40 by means of the component 35 , The component 35 can, for example, as a roller rotary valve, as a linearly movable slide, or as in the DE 199 08 435 A1 described, be designed as electromagnetically controllable flaps.

The function of the described arrangement is as follows:
Assuming the inlet valve 20 is to and in the vibration tube 16 is no flow towards the inlet valve 20 available. The component 35 closes the flow cross-section 40 Completely. If at a suction stroke now the inlet valve 20 is opened, arises in the region of the vibrating tube 16 downstream of the component 35 an increasing negative pressure. Depending on the desired charge or other desired thermodynamic parameters, the component 35 controlled such that it has the flow cross-section 40 at least partially releases. The at least partial opening of the flow cross section 40 takes place advantageously abruptly, so that the previously generated negative pressure causes a very high flow velocity. The very fast flow of the inlet air column in the vibration tube 16 or in the intake manifold 30 leads in particular at low to medium engine speeds of the internal combustion engine 1 to significant recharge effects with corresponding fill increments in the cylinder 2 , Will the inlet valve 20 then for the compression stroke of the piston 4 closed, then the component 35 controlled such that it has the flow cross-section 40 completely closed again, so that the cycle described can start again. The opening and closing of the component 35 For example, in the from the DE 199 08 435 A1 done manner described.

The activation of the component 35 can advantageously also be such that in certain load conditions of the engine, for example, at low speeds, the component 35 the flow cross section 40 at the end of an intake stroke already closes before the intake valve 20 closes. This can be a return flow of the fresh charge through the vibration tube 16 reliably prevented.

By means of the device 5 the fuel is in the intake manifold 30 preferably with the inlet valve open 20 injected. After opening the flow cross-section 40 through the component 35 can the pressure in the intake manifold 30 especially on the device 5 for fuel injection, which may be formed for example as an injection valve, or in front of the inlet valve 20 change greatly, for example by about 1200 mbar. This strong change in pressure in the intake manifold 30 results from the rapid or sudden opening of the flow cross section 40 , as described above. Such a pressure change has a strong influence on the injected fuel quantity. This means that at the same opening cross-section of the injector 5 the fuel flow significantly changes or increases. The fuel pressure can be assumed, for example, as currently usual, with 3 bar.

In order to inject a given amount of fuel, so must the pressure change in the intake manifold 30 be taken into account. Depending on the control of the component 35 is the flow area 40 closed during the intake phase or during a suction stroke for different lengths, so that a different pressure change or a different intake manifold pressure when opening the flow cross-section 40 results. This intake manifold pressure can be dependent on the control of the component 35 for adjusting the shutter speed of the flow cross section 40 be modeled during the suction stroke. Depending on the modeled intake manifold pressure then the injection time for the injection of the fuel into the intake manifold 30 be adjusted or corrected. The shutter duration of the flow cross section 40 depends essentially on the opening time of the flow cross-section 40 when the shutter time is still before the beginning of the suction stroke, as may advantageously be the case. Thus, the injection time in dependence of the opening time of the flow cross section 40 be set.

In this case, the intake manifold pressure by means of the pressure sensor 55 be measured. The when opening the flow cross-section 40 measured pressure in the intake manifold 30 then performs the appropriate adjustment of the injection time according to the model formed.

When the engine is cold or when starting the engine, there are usually pronounced wall film effects. This means that much of the injected fuel is deposited on the intake manifold wall. The optimum amount of fuel for combustion in the combustion chamber 18 is therefore only vaguely determinable. If now the fuel injected at the time of the highest air velocity in the intake manifold, it comes to lower wall film effects, since the fuel into the combustion chamber 18 being carried away. Due to the increased flow velocity of the intake air after opening the flow cross section 40 The then injected fuel not only gets faster into the combustion chamber 18 but also with smaller droplet size. Due to the smaller droplet size, a better ignition and combustion of the fuel-air mixture in the combustion chamber 18 causes. This is due to the fact that the fuel with a smaller droplet size spreads better in the combustion chamber and burns better. Under these circumstances, the ignition angle can be delayed or retarded further, whereby a faster heating of an in 1 not shown catalyst in the outlet channel 22 is favored. Additionally or alternatively, the better ignition and combustion of the fuel-air mixture due to the increased flow rate also allows a reduction in the amount of fuel to be injected and thus an emaciation of the fuel-air mixture with the aim of less fuel surplus in the combustion and thus less hydrocarbon emissions realize.

Because the fuel faster due to the increased flow rate in the combustion chamber 18 is the residence time of the fuel in the combustion chamber 18 greater until the onset of ignition and combustion, allowing for better vaporization of the fuel. Due to the better evaporation is a cooling of the fuel-air mixture in the combustion chamber 18 causes a self-ignition and thus a knock tendency lowers.

In order to exploit the described positive effect of the increased flow velocity on the fuel caused by the impulse charging, it may additionally be provided that the injection time is dependent on the flow rate in the intake manifold influenced by the impulse charging 30 adjust. In this case, the fuel injection can be initiated in particular at the time of the highest flow velocity. For this purpose, the flow rate sensor is used 60 , which measures the measured flow velocity in the intake manifold 30 about the means 80 to the means 45 for controlling the device 5 for fuel injection forwards.

In the timetable according to 4 an example of a sequence of the method according to the invention is shown. The signal curve S is plotted over the time t. A first signal S1 shows the activation of the component 35 , Until a first time t ₁ , the first signal S1 has a low level, which closes the flow cross section 40 by means of the component 35 causes. At the first time t ₁ , the first signal S1 goes to a high level and causes the component 35 for the at least partial and sudden opening of the flow cross-section 40 , Until the first time t ₁ , as described, a corresponding negative pressure in the intake manifold 30 constructed after opening the flow cross-section 40 degrades again. After opening the flow cross-section 40 increases the flow velocity in the intake manifold 30 strong, like that in 4 illustrated third signal 53 clarified. At a second time t ₂ , the flow velocity reaches a maximum value, at the detection of which the means 45 an opening of the injection valve 5 as indicated by the positive edge of the second signal S2 in FIG 4 at the second time t _{2 is} shown. The means 45 cause the injection valve to close 5 then at a third time t ₃ following the second time t ₂ . The resulting in this way injection time t _E = t ₃ - t ₂ is thereby from the means 45 as a function of the pressure curve and / or the flow velocity course in the intake manifold 30 adjusted to a predetermined amount of fuel in the intake manifold 30 inject.

The start of injection at the second time t ₂ is delayed by the time difference A with respect to the first time t ₁ . In general, a corresponding adaptation of the second time t ₂ , at which the fuel injection begins and which is referred to below as the injection time, at all operating points, for example, even when the engine is warm. In the practical implementation of a map can be used, which has as input the engine speed and the modeled or measured intake manifold pressure and the output as the injection time or the time difference A according to 4 supplies. Thus, the start of injection depending on the opening time of the flow cross section 40 be set. An optimization of the time difference A can then take place by means of an application by at least one parameter of the internal combustion engine 1 depending on the time difference A is measured. The value for the time difference A, at which the at least one parameter assumes the optimum value, is then stored in the map as the output variable for the corresponding intake manifold pressure and the corresponding engine speed. Instead of the intake manifold pressure, another variable associated with the intake manifold pressure may be used to implement the characteristic map, for example the flow velocity, the charge, or another variable characterizing the load. As a parameter for optimizing the time difference A, for example, the exhaust gas emission or the engine temperature can be used. The time difference A can then be optimized for the operating point of the characteristic field defined by load and speed in such a way that a minimum of the exhaust emissions, for example of the hydrocarbon emissions, is achieved for the respective operating point.

Claims (8)

Method for controlling an internal combustion engine ( 1 ) with impulse charging ( 26 ) and fuel injection ( 5 ) in a charge exchange channel ( 30 ), where the impulse charging ( 26 ) operated, characterized in that the Injection duration depends on the activation of the pulse charging ( 26 ) is set. Method according to Claim 1, characterized in that the activation of the pulse charging ( 26 ) a control of a component ( 35 ) for opening and closing a flow cross-section ( 40 ) of the charge exchange channel ( 30 ) and that the injection duration depends on the activation of the component ( 35 ) is set. A method according to claim 2, characterized in that the start of injection in dependence of an opening time of the flow cross-section ( 40 ) is set. Method according to one of claims 2 to 3, characterized in that depending on the activation of the component ( 35 ) the pressure in the charge exchange channel ( 30 ) and that the injection duration is set as a function of the modeled pressure. Method according to one of the preceding claims, characterized in that the injection duration as a function of the pulse charging ( 26 ) influenced flow velocity in the charge exchange channel ( 30 ) is set. A method according to claim 5, characterized in that the fuel is injected at the time of the highest flow velocity. Method according to one of the preceding claims, characterized in that the injection duration as a function of a in the charge exchange channel ( 30 ) measured pressure is adjusted. Contraption ( 50 ) for controlling an internal combustion engine ( 1 ) with impulse charging ( 26 ) and fuel injection ( 5 ) in a charge exchange channel ( 30 ), wherein a control of the pulse charging ( 26 ), characterized in that means ( 45 ) for controlling the injection duration as a function of the activation of the pulse charging ( 26 ) are provided.

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