DE3135691A1 - LOAD CONTROL OF AN INTERNAL COMBUSTION ENGINE CHARGED WITH AN EXHAUST TURBOCHARGER - Google Patents

Description

Load control one with one

Turbocharger supercharged

Internal combustion engine

The invention relates to the load control of an exhaust gas turbocharger supercharged internal combustion engine according to the preamble of claim 1.

In engines with exhaust gas turbochargers, the negative gas exchange work is thereby reduced in the throttled state (partial load) increases the fact that the exhaust gas turbine built into the exhaust line builds up the exhaust gas pressure. From the exhaust gas through the turbine and compressor transferred to the charge air in the form of pressure Energy is not required and is therefore reduced again with the throttle valve. Which increased due to the pent-up exhaust gas pressure Gas exchange work worsens the efficiency of the engine and thus increases fuel consumption.

The object of the invention is, through an appropriate interaction of the actuators for the throttle valve and the bypass valve of the turbocharger turbine to improve the overall load control of the engine in order to achieve the Perfect driving behavior and especially fuel consumption to lower.

To solve this problem, a control circuit with the characterizing features of claim 1 proposed. It enables the turbocharger turbine to run at low To apply part load with so much exhaust gas that they and the your synchronous compressor run at a low basic speed. The engine reacts more quickly to the actuation of the accelerator pedal because the turbocharger reaches the required target speed or the required speed more quickly when there is a spontaneous power demand

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required boost pressure generated. At the same time, a smooth transition to turbo operation is achieved and the driving behavior is abrupt of the vehicle.

With the electronic control of the throttle valve and the bypass valve according to claim 2, the load control can be exactly to the respective existing values of the parameters determining the mixture formation and combustion: engine speed as well as the pressure and temperature of the charge air, these parameters being scanned electronically with the Accelerator pedal position are linked. According to claim 3 act on the actuator of the power control organs throttle valve and bypass valve do not have these parameters themselves, but control variables corresponding to them, which are used as output signals non-linear function converter can be obtained. By choosing the functional relationship between the measured input parameter and for controlling the output variable used, the load control of the motor can be controlled in an optimal manner Adjust operating conditions. Furthermore, a signal can be obtained from the speed of the accelerator pedal movement, which causes the bypass valve to close via the actuator and thus brings the turbocharger to full speed, as soon as or shortly before the throttle valve is fully open. Does the turbocharger have the target speed or full boost pressure reached, it is throttled again by opening the bypass valve. In this way, a desired achieve maximum vehicle acceleration.

A circuit diagram of the load control according to the invention is in FIG Drawing shown and is explained below. Show it

Fig. 1 block diagram of the load control Fig. 2, 3 and 4 electronic circuits of the function converter.

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The signal from an electrical sensor 1 for the accelerator pedal position tf , which is obtained via a potentiometer ter abgr if f, is fed in a first line 2 to an angle function converter 3 / which, according to a predetermined function, corresponds to the rotational angle f of the accelerator pedal at a rotational angle c < _{2 is assigned to} ^the throttle valve in such a way that, starting at angular position 0, the throttle valve angle increases according to a root function with the accelerator pedal angle until the throttle valve is fully open in angular position ec_ max. The angle o £ _ corresponding to this function profile is fed into a computing circuit 4 _{together with a control signal n 2 obtained from the engine speed.} The speed control signal n »is the output signal of a speed function converter 5, which converts the engine speed n ₁ detected via a speed sensor 6 into a speed signal n« according to a mathematical function that increases with the turning point. The output signal of the computing circuit 4 is given to an electric servomotor 7 for the throttle valve, which adjusts it by the angle oc.

In a further line parallel to the first line 2, the accelerator pedal position £ is stored in a function converter 9 which, according to a predetermined function, supplies a control signal β ~ for the position of the bypass valve of the exhaust gas turbocharger as an output variable. If the accelerator pedal angle ^ f = 0

ßo ~ ßi ^max · '^ as the bypass valve is fully open, the exhaust gas turbocharger is out of operation. When the accelerator pedal is about halfway down, the control signal β _ decreases with increasing J * after a hyperbola or e-function, that is, from here the turbocharger turbine is increasingly acted upon. The actual position / 3 of the bypass valve also depends on the control signals ρ ₂ and ^ ₂ for the pressure or the temperature of the charge air, which together with the control signal β _

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a computation circuit 10, which combines all input signals additively or multiplicatively with each other »With the output signal of the computation circuit 10, an electric actuator 11 of the bypass valve is controlled, which is adjusted by the travel ß. The pressure control signal p »is generated in a function converter 12 whose input signal ρ. originates from a pressure transmitter 13 connected to the charge air line. The pressure control signal ρ "decreases according to a continuously decreasing function with increasing p * , that is, with increasing pressure of the charge air, the closing movement of the bypass valve and thus the increase in charge of the internal combustion engine are reduced. The temperature of the charge air, on the other hand, influences the adjusting movement of the bypass valve according to a completely different function. The temperature control signal (J * ₂ , which is obtained in the function converter, is initially approximately constant with increasing temperature $ .. of the charge air, which is measured with a temperature sensor 15. With increasing temperature, J * ₁ rises ^ ₂ abruptly and causes a strongly accelerated closing movement of the bypass valve. If the charge air temperature ^ ₁ increases further, $ „remains at a constant level again.

By selecting the functional relationships between the measured engine parameters obtained in the function converters and the control variables assigned to them, the load control of the internal combustion engine can be carried out very precisely optimize.

The circuits of the function converter known from the book semiconductor circuit technology, 3rd edition, page 274 are in FIGS. 2, 3 and 4, the operational amplifiers for negative input voltages being omitted in the present application. For each of the function converters 3, 9, 5,

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and 14, a circuit consisting of the sub-circuits is used according to Fig. 2, 3, 4, depending on the course of the characteristic, several subcircuits according to FIG. 2 are present and the Partial circuit according to FIG. 3 is only required for the function converter 9, 12 and 14. The output current at terminal 17 of the Partial circuit according to FIG. 2 is of the input voltage at terminal 16 and of the setting of the potentiometers 18 and 19 addicted. With 18 a minimum value for the input voltage becomes specified, up to which the current flow at 17 is equal to 0. at higher input voltage, the current flow is proportional to the Input voltage, the proportionality factor being adjustable on the potentiometer 19.

With the subcircuit according to FIG. 3, a constant current flow which is independent of the input voltage and which flows through the potentiometer 20 is adjustable. The output currents of the subcircuits according to FIGS. 2 and 3 are fed to terminal 21 in supplied to the circuit of FIG. 4; they are added and converted into a proportional output voltage at terminal 22. With These function converters can be used to create any characteristic curves that consist of a constant part and several Shares with variable rise or fall can be composed.

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Claims (3)

W. Claims 1J Load control of a turbocharger charged with an exhaust gas turbocharger Internal combustion engine, in particular for motor vehicles with electric actuators for the throttle valve and one Bypass valve through which exhaust gas flows directly into the exhaust line, bypassing the turbocharger turbine, characterized in that that in the lower partial load range of the internal combustion engine (up to approx. 50% of full load) the bypass valve has a assumes a constant, almost fully open position, whereby the turbine and the compressor of the turbocharger operate at low, run constant speed, and that for load control, the throttle valve is opened from 0% to 100%, while in the upper Partial load range the throttle valve is fully open and the load control by closing the bypass valve and accordingly high loading of the turbocharger turbine takes place. 2. Load control according to claim 1, characterized in that the throttle valve by the accelerator pedal position and the engine speed is controllable, and that the bypass valve by the accelerator pedal position and the pressure and temperature of the charge air is controlled, the respective interacting control variables being linked additively or multiplicatively. 3. Load control according to claim 2, characterized in that the control variables as output signals from non-linear function converters (6, 13, 15) of the measured motor parameters: Engine speed as well as pressure and temperature of the charge air can be obtained.