DE2748871A1 - Vehicle engine fuel and air supply control system - has exhaust gas oxygen monitor cut out when engine speed increases - Google Patents

Abstract

The control system for regulating the fuel and air supply to a vehicle engine as in the main patent, is designed to prevent uneven running while idling. The system includes a probe in the exhaust gas line to measure the oxygen content of the exhaust gases. This device is cut off when the engine speed exceeds a given value. When this happens, a fuel supply timing valve operates to give a constant timing of the fuel injection. This occurs after a switch dependent on load, suction or rotary speed has operated.

Description

"Brennkarftmaschine"

Addendum to patent. ... ...

(I> atentanmeldung 1> 27 39 992.4) The invention relates to a Urennkraftmaschine with an arbitrarily controllable metering device for the Metering of fuel to the combustion air according to the desired load and with a probe in the exhaust pipe to determine the O2 content in the exhaust gas, which corrects the fuel metering to the stoichimetric composition - sensor control - whereby the effect of the probe control is switched off in overrun mode above the limit number is, according to patent. ... ... (patent application P 27 39 992.4).

The internal combustion engine described in the main patent of the invention Avoids over-greasing caused by the probe control in overrun mode the air-fuel mixture.

However, the O2 probe control has the disadvantage that due to the control characteristics irregular idling is possible. This irregularity is due to control oscillations in the soug pipe or fuel system, with alternating bold and lean mixture is supplied. The idling speed fluctuation will also referred to as idle saws.

In addition, there are strong IIC and CO peaks in the exhaust gases during overrun on. The reason for this is that the exhaust gas mixture in the push phase briefly Ä> 1 in front of the probe. The probe control tries the starko lean to compensate for the air-fuel mixture through the appropriate metering of fuel, however, there is a strong overshoot in the rich area.

By increasing the thrust, a flutter valve in the throttle valve or in the fuel shut-off, the IIC and CO peaks in the exhaust gas can be eliminated will. A thrust increase or a flutter valve is expensive, however, a corresponding one de Fuel cut-off usually difficult.

The object of the present additional application is to provide an internal combustion engine with a special regulation according to the main patent to the effect that in idle mode This prevents fluctuations in speed and prevents the mixture from becoming too rich in overrun and thus IIC and CO peaks in the exhaust gases are avoided.

According to the invention, this object is achieved in that for fuel measurement a clock valve and a clock valve control are provided, which are switched off the probe control will take effect automatically in coasting or idling mode and that a fixed cycle ratio is specified or the control characteristics of the O2 special control is changed.

If the O2 sensor control is switched off, the clock valve is also activated a predetermined fixed opening / closing ratio adapted to the vehicle (Duty cycle) applied so that a mixture setting is achieved that corresponds approximately to λ = 1. By this predetermined uniform fuel supply when the probe control is switched off, the speed remains constant while idling In overrun operation, enrichment is prevented by the switched off O2 probe.

If there is a change in the control characteristics of the 02-probe control larger # oscillations, which are caused by the control, are excluded. The clock ratio remains variable in this case.

Furthermore, the clock valve control can be in the range of the idle load, vacuum or speed-dependent actuated switches. This switch can e.g. nls vacuum switch, accelerator pedal switch, speed sensor, throttle valve contact etc. trained seiii and switches the ercitschaftsatell in idle and overrun a.

On the basis of an exemplary embodiment shown schematically in the drawing the invention is to be explained in more detail.

The figure shows a circuit diagram according to the invention.

Received from a speed transmitter or vacuum switch (signal transmitter) 1 the i: input signal via an electronic relay 2, which actuates a switch 3, which establishes the connection with the O2 sensor control 4. On relay 2 is on Control unit 5 connected, which has a predetermined pulse duty factor for a clock valve 6 pretends. The control unit 5 is activated by the relay 2 when a certain input signal is received (speed or vacuum dependent) switched on if the O2 probe control is now Operation is. This is also the case if, for example, the O2 probe is defective or the probe contact temperature of 3000C has not yet been reached. That s air-fuel mixture is held by the control unit 5 and the timing valve 6 at a value that approximates # = 1 is.

Claims (2)

Claims 1. Internal combustion engine with an arbitrarily controllable Metering device for metering fuel to the combustion air accordingly the desired load and with a probe in the exhaust pipe for determination the O2 content in the exhaust gas, which determines the fuel metering on the stoichiometric composition corrected - probe control -, whereby the effect of the probe control in overrun mode is switched off above a limit speed, according to patent. ... ... (patent application P 27 39 992.4), characterized in that a clock valve for the fuel metering and a clock valve control are provided, the shutdown of the probe control in the club or become automatically effective in idle operation and that a solid Cycle ratio specified or the control characteristics of the O-sensor control changed will. 2. Internal combustion engine according to claim 1, characterized in that the timing valve control by a load, negative pressure or speed-dependent operated switch takes place.