DE10036579A1 - Fuel injection control system for internal combustion engine has data of injection changed, before transition from first into second state, so emissions are approximated to those in second state - Google Patents

Abstract

The procedure is for the control of the fuel injection in an internal combustion engine. It enables discrimination at least between a first state and a second state. Directly before the transition from the first state into the second state, the data of the injection are changed so that the emissions, especially the noise development, are gradually approximated to the emissions in the second state. In the first state, at least one first part injection and second part injection take place and in the second state, no first part injection takes place. The emissions are continually increased. The amount and/or frequency of the first part injection is/are changed.

Description

State of the art

The invention relates to a method and a device to control fuel injection into an internal combustion engine machine according to the preambles of the independent claims.

Such a method and such a device for control tion of fuel injection into an internal combustion engine is known for example from DE 197 12 143. In the The procedure described there will be the fuel injection into a pre-injection and into a main injection split. The pre-injection can make noise missions are significantly reduced.

Pre-injection is often not carried out in all operations states. This means in a first operating state there is a pre-injection and in a second operation state there is no pre-injection. With the abrupt Um switch from a state with pre-injection to a loading operating state without pre-injection occurs suddenly the combustion noise rose. This increase in Burning noise is very irritating by the driver felt.

Advantages of the invention

With the procedure according to the invention, the sudden Increase in combustion noise when transitioning from one Operating state with a first partial injection and second partial injection in an operating state without the first Partial injection can be significantly reduced. In the first Partial injection is preferably a pre-injection injection immediately before the second partial injection tion, which is also referred to as the main injection, he follows.

This is achieved according to the invention in that before Transition from a first state to a second state without pre-injection change the noise in such a way is changed that the level of noise emissions before Transition and approximate after the transition. This will do so achieved that the data of the injection changed so be that the noise emissions before the Transition in the second state to the noise emission in the adjust second state. In particular, the duration and / or the frequency of the pre-injections is changed.

The data of the pre-injection are usually selected so that that there is a minimum of noise emissions. Invention according to it was recognized that by increasing or decreasing a noise adjustment can be made to the pre-injection quantity. There is an extension of the duration of the pre-injection particularly advantageous.

In a further embodiment it can be provided that the transition to a state without pre-injection injections are continuously hidden more and more frequently becomes. This means that immediately before the transition  nth pre-injection is omitted. The number n starting from a large value according to a certain scheme slowly lowered to 1. This means, for example shows that every 10th injection is hidden at the beginning and at the end of the transition, all injections are blown out be det.

drawing

The invention is described below with reference to the drawing illustrated embodiments explained in more detail. Show it

Fig. 1, a fuel metering system, shown schematically as a block diagram, Fig. 2, the timing diagrams of three injections and Fig. 3 and 4 each show a flowchart of the procedure according to the invention.

In Fig. 1, the essential elements of a fuel metering system of an internal combustion engine are shown schematically as a block diagram. An internal combustion engine is designated 100 . This is metered into fuel via a fuel metering device 110 . A control unit 120 applies control signals VE and HE to the fuel metering device. Output signals from various sensors 130 are fed to the control unit.

The sensors 130 record various operating parameters, the internal combustion engine and various environmental conditions. These are, in particular, signals relating to the speed of the internal combustion engine and various temperature and pressure values. Based on these signals and the driver's request, the control unit 120 calculates the signals VE and HE with which the fuel metering device 110 is applied.

Especially with direct-injection diesel internal combustion The amount of fuel to be injected seems to be small  At least one pre-injection and one main injection Splits. In addition to the pre-injection and the main injection are other partial injections, like a second pre injection and / or post-injection possible. Because The main injection can also be divided into additional ones Partial injections are divided. In the illustrated The exemplary embodiment is only a pre-injection and a main injection is provided.

The signal VE determines the pilot injection and the HE determines the main injection. The signals essentially determine the start and the amount of the respective injection. Depending on these signals, the fuel metering device 110 measures a corresponding amount of fuel in the internal combustion engine 100 .

In Fig. 2, the injection profiles, that is, the control signal for the fuel metering device or a corresponding size are plotted against time t. The pre-injection is again labeled with VE and the main injection with HE.

FIG. 2a shows an operating state in which a pre-injection takes place. Approx. 5% of the injection quantity is pre-injected. In part figure 2 c is an injection without pre-injection represents Darge. In Fig. 2b the transition from the state with pre-injection to the state without pre-injection is Darge.

During the transition, the amount of pilot injection will increase high, d. H. the duration of the pre-injection becomes continuous extended. Preferably, the amount of main injection reduced by a corresponding amount, the so ge is chosen that the delivered torque remains constant.  

If the noise level reaches the value that is usually in this operating state is achieved without pre-injection, the pre-injection VE is set to zero and the main injection shifted towards early.

This means to the sudden increase in combustion reduce noise after switching off the pre-injection grace, the combustion noise according to the invention the deactivation of the pilot injection increases continuously. For this purpose, the pre-injection quantity is used in this embodiment raised up to 60% of the total injection quantity. The first injection quantity is increased so far that the combustion pressure gradient at the time of ignition of the pre-injection ent pressure gradient during operation without pre-injection ent speaks. The combustion pressure gradient corresponds to the change combustion pressure at the time of ignition.

As a result, the combustion noise is immediately before Ab circuit of the pre-injection approximately equal to the combustion after the pilot injection has been switched off.

It is particularly advantageous that the increase in advance amount of spray not only a reduction in noise, son also a shift in the focus of combustion effected early. This reduces the required Injection adjuster position jump, which for the compensation of the Injection start of the main injection when switched off the pre-injection is necessary.

When switching to the state without pre-injection must the focus of combustion is adjusted in the direction of who the corresponding consumption values and / or emissions values or a corresponding torque of the internal combustion engine is delivered. By increasing the The pre-injection quantity is shifted towards early  focal point towards early. The difference between the focus of combustion when switching off the Vor injection is in this embodiment of the invention significantly smaller than with other switching strategies.

In a second embodiment of the invention The combustion noise before switching off the pilot injection increases in that the pilot injection when transitioning to a state without pre-injection next turned off for individual injections, d. H. out is dazzled. This individual shutdown of the pilot injection in the case of individual metering, the frequency is relative designed that it increases continuously. This means: The pilot injection is carried out at every nth injection dazzles. The number n is continuously increased by a ho hen value reduced to a lower value, preferably 1. With the value 1 there is no pre-injection, with a high one Value is practically every pre-injection. The pattern of injections that are switched on and off are based on psy coordinated choacoustic concerns.

In Fig. 3 the procedure according to the invention is shown as a block diagram. A first query 300 checks whether there is an operating state in which the pilot injection is to be switched off. If this is not the case, query 300 is repeated. If this is the case, a time counter T is set to zero. Then in step 320 , the time counter T is increased by 1. In the subsequent step 330 , the pre-injection quantity VE is increased by the value D. The query 340 checks whether the time counter is greater than a threshold value TS. If this is not the case, step 320 takes place again. If this is the case, the pilot injection VE is set to zero in step 350 , ie switched off and the main injection adjusted accordingly. In the illustrated embodiment, the transition from a state with a state without a pre-injection takes place.

According to the invention, instead of the time query 340, a corresponding query can be carried out, in which it is checked whether the duration and / or the amount of the pilot injection VE is greater than a threshold value. Alternatively, it can also be provided that another measured variable is checked to determine whether a threshold value has been exceeded and then step 350 follows.

In a further embodiment of the invention way, the combustion noise will go off before turning off the pre-injection increased by immediately before or by switching off the pre-injection of the fuel pressure is temporarily reduced. This creates an intermediate level of noise emissions between operation with and without Pre-injection reached. It is particularly advantageous when reducing fuel pressure and stopping pre-injection simultaneously with the reduction of the fuel pressure. This can avoid that when operating with pre-injection and reduced power increased particle emissions in the short term occurs.

In FIG. 4, the procedure of the invention is shown as a block diagram. A first query 400 checks whether there is an operating state in which the pilot injection is to be switched off. If this is not the case, the program continues with step 450 in normal operation. If query 400 recognizes that the pilot injection is to be switched off, then in step 410 the fuel pressure P is reduced by a specific value x.

This is preferred in a so-called common rail system wise achieved that the setpoint of a rail pressure  is reduced by a corresponding amount. Dude natively it can be provided that a pressure rule for a short time valve is controlled accordingly. With other strength Substance metering systems are other suitable measures for Lowering the fuel pressure used.

In the subsequent step 420 , the pilot injection VE is set to zero. That is, the pilot injection is switched off in step 420 . The subsequent query 430 checks whether a time condition is fulfilled. If this is not fulfilled, query 430 is repeated . If the time condition 430 is fulfilled, ie the pressure is reduced for a certain time, the pressure p is increased to its old value in step 440 . The program then continues its normal operation in step 450 .

It is particularly advantageous if steps 410 and 420 take place simultaneously.

It is particularly advantageous, even if the transition from a state without pre-injection to a state with pre injection is proceeded accordingly. For example can be provided that the number of pilot injections not abruptly but continuously on the intended Value is increased.

The procedure can also be used for systems with more are used as two partial injections.

Claims (8)

1. A method for controlling the fuel injection in an internal combustion engine, a distinction being made at least between a first state and a second state, characterized in that, immediately before the transition from the first state to the second state, the data of the injection are changed in such a way that the emissions, especially the noise, are gradually brought closer to the emissions in the second state. 2. The method according to claim 1, characterized in that in the first state at least a first partial injection and a second partial injection takes place and in which two no partial injection takes place. 3. The method according to any one of claims 1 or 2, characterized ge indicates that emissions are continuously increasing become. 4. The method according to any one of the preceding claims characterized in that the amount and / or the frequency speed of the first partial injections is changed.   5. The method according to any one of the preceding claims characterized in that the set of the first parts injection is increased. 6. The method according to any one of the preceding claims, since characterized by the number of first parts injections is continuously reduced. 7. The method according to any one of the preceding claims characterized in that a fuel pressure is lowered becomes. 8. Device for controlling the fuel injection in an internal combustion engine, at least between one distinguished first state and a second state is characterized in that means are provided the immediately before the transition from the first state in the second state, the data of the injection change that emissions, especially noise development, gradually to the emissions in the second Condition to be approximated.