EP1012462B1 - Method for determining an operation parameter for the starting of an internal combustion engine - Google Patents

Description

The invention relates to a method for determining an operating parameter for starting an internal combustion engine, in particular to determine the fuel mass to be injected, according to the preamble of claim 1.

An internal combustion engine can be started without special regulation when starting with the help of a start function is carried out. This function calculates depending the operating parameters, e.g. the coolant temperature and the speed from several maps one or more parameters for the injection system with which the internal combustion engine is started. Then is a certain idle speed is reached, the system switches to speed control. Difficulties arise from the fact that the same Starting behavior with very different operating parameters should be achieved.

The starting process using the start function is shown in Fig. 3. As soon as the speed of the internal combustion engine has reached the speed N _ST with the aid of the starter, the fuel mass m is injected during the time between t1 and t2 in accordance with the aforementioned function. From time t2, the speed controller takes over control of the internal combustion engine. This leads to a strong overshoot of the speed N during the starting process until the idling speed N_SOLL is finally reached. When specifying this function, in order to avoid overshoot and to maintain reproducibility of the start processes, all cross influences in the start function must be taken into account, since the function is a control

There is also a computer-controlled injection system for diesel engines known (DE 30 09 627 C2), the control of the Starting valves at the start of the start and the trigger angle for the Injection process depending on the crankshaft angle with a special program is calculated.

The invention is therefore based on the object of or to improve the starting behavior of an internal combustion engine.

The stated object is achieved with the features of the patent claim 1 solved. Advantageous further developments are in the Subclaims marked.

According to the invention, the starting process takes place with a controller, especially the already existing speed or idle controller, the one for starting with one parameter, in particular the fuel mass is initialized. This parameter, which is fed to the controller at the start of the start process is of different operating parameters of the internal combustion engine dependent and is dependent on a characteristic curve from the coolant temperature in the control unit of the Internal combustion engine stored. According to the initialization the internal combustion engine is then accelerated to idle speed using the controller. This gives better starting behavior and the problem of the transient response to the idle speed, as is the case with Application of the start function does not occur. A special The advantage is that the starting process with the help of the speed controller, which is already provided in the control unit is and thus has an expanded scope.

Fig. 1

ein Blockschaltbild eines Drehzahlreglers,

Fig. 2

den Verlauf von eingespritzter Kraftstoffmasse und der Drehzahl nach dem erfindungsgemäßen Verfahren;

Fig. 3

den Verlauf von eingespritzer Kraftstoffmasse und der Drehzahl bei Vorgabe einer Startfunktion

An embodiment of the invention is explained below with reference to the drawing. It shows:

Fig. 1

a block diagram of a speed controller,

Fig. 2

the course of the injected fuel mass and the speed according to the inventive method;

Fig. 3

the course of the injected fuel mass and the speed when a start function is specified

In Fig. 1, a speed controller 1 is shown, which consists of a Difference DIFF between a target speed N_SOLL and the Actual speed N a fuel mass m (manipulated variable) is calculated. With this output signal of the controller 1 is a not shown Injector controlled.

For the start, the controller 1 with a fuel mass I initialized. The parameter I is preferably made up of a Characteristic curve taken depending on the coolant temperature. This parameter determines the fuel mass for the first injection that takes place at the start of the starting process.

2 shows the time profile of the injected fuel mass m. When a certain starter speed N _{ST is} reached, the first injection predetermined by the initialization I takes place, and the curve m rises steeply. Starting from the initialization value I, the fuel mass to be injected is then calculated by the controller 1, so that the speed N approaches the setpoint N_SOLL without the transient events shown in FIG. 3 occurring. According to FIG. 2, the control results in a better and reproducible starting behavior. The noise behavior and the exhaust gas emissions during the starting process are improved. The computer effort for the starting process can thus be significantly reduced by simply specifying the initialization value I for the speed controller.

Claims (4)

1. Method for starting an internal combustion engine whereby certain operating parameters determined from characteristic variables, particularly the amount of fuel to be injected (m), are supplied to the fuel injection system, characterised in that as an output variable for starting, an initialisation value (I) is input to a speed governor (1) and based on the initialisation value (I) the speed (N) is increased to the idling speed (N_SOLL) by the speed governor (1).
2. Method in accordance with claim 1, characterised in that the control function is exercised by the speed governor which is present in the engine control unit.
3. Method in accordance with one of claims 1 or 2, characterised in that the initialisation value is stored in a curve relative to the coolant temperature.
4. Method in accordance with one of claims 1 to 3, characterised in that the initialisation value applies for the first fuel injection action of the internal combustion engine.

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