Abstract: The composition of the combustible mixture supplied to an internal combustion engine is controlled in dependence on the fluctuations in cylinder pressure which are monitored by sensing the fluctuations in the rotation of the engine crankshaft. These fluctuations are measured by comparison with a signal which simulates an engine running uniformly at the basic engine r.p.m. The signal which characterizes the r.p.m. fluctuations is compared with a nominal or command value and the resulting signal is used to control the mixture composition so as to maintain the fluctuations within predetermined limits.

Abstract: A method and apparatus for detecting cylinder malfunction by monitoring the actual rotational speed in an internal combustion engine, e.g. with an inductive transducer. This signal is compared in phase with pulses from a voltage controlled oscillator, the control voltage of which comes from an integrating circuit driven by the phase comparison signal in the manner of a phase-locked loop.The VCO pulses are used to clock a shift register and the actual pulses provide the data input for the shift register. Thus, the relative arrival time of the two pulse trains determines the contents of the shift register. Decoding circuitry is used to interrogate the shift register and to actuate an output device when the contents of the register indicate an unsymmetric periodicity, caused by cylinder malfunction.

Abstract: A fuel metering system of an internal combustion engine is controlled by an analog computer circuit which delivers injection pulses to actuate the fuel injection valves of the engine. The duration of these pulses is directly related to the amount of injected fuel and depends partly on the inherent electrical characteristics of the components of the analog computer circuit. The pulse duration also depends on the instantaneous values of at least two engine parameters, r.p.m. and throttle valve position, i.e., the degree of opening of the air inlet valve. The r.p.m. signal is sensed by an appropriate transducer and triggers a monostable multivibrator in the analog computer circuit while the throttle valve position is sensed by a potentiometer and defines the charging rate of a capacitor. The voltage on the capacitor influences the action of the monostable multivibrator which delivers the fuel injection pulse.

Abstract: The fuel mixture ratio of an internal combustion engine is adjusted by metering out a fuel quantity in relation to the air flow rate through the induction tube. The air flow rate is measured indirectly by monitoring the engine speed (rpm) with an electrical transducer driving a frequency-voltage converter, thus providing a first voltage, while a throttle plate position transducer generates a second voltage. The two voltages are applied to a logical circuit including parallel diodes which selects the lower of the applied signals and presents the resultant voltage as the primary control signal for fuel metering. Various compensating networks may be added to provide additional smoothing and adaptation to the operating characteristics of a particular engine and state of operation. Various fuel metering devices to be used in conjunction with the control circuit are also described.

Abstract: A process for controlling the operation of an internal combustion engine based on the volumetric efficiency of the engine to define a primary nominal fuel quantity. The process also includes measuring the fluctuations in the volumetric efficiency. In order to operate the engine in a preferred leaned-out condition, a nominal set-point value of the permitted range of fluctuations of the volumetric efficiency is established and the actual measured fluctuations are maintained in that range by changing the fuel metered out to the engine.Various methods for measuring the volumetric efficiency indirectly by pressure measurements in the induction tube are presented.

Abstract: An internal combustion engine is operated in the lean-running condition where measurable engine roughness occurs. The degree of this engine roughness, which is due to fluctuations in acceleration, is measured and compared with set-point values in a fuel metering control loop. In order to prevent undesirable control characteristics, the effect of positive changes in acceleration is prevented from engaging the final control element by a switching element which interrupts the signal flow to the final control element during positive changes in engine accelerations.

Abstract: A control apparatus for an internal combustion engine performs cyclic modulations of an operational parameter of the engine, for example by periodic leaning out of the fuel-air mixture to some of the engine's cylinders. The resulting changes in angular acceleration of the crankshaft are sensed by an electro-inductive transducer and the elapsed time between successive pulses so generated is measured. Depending on whether the change in acceleration is positive or negative, the circuit generates an appropriate control signal which may be used to steer a final control element which moves the center of modulation, i.e., the operational point of the engine, toward an optimum value of, for example, the fuel-air ratio.

Abstract: A fuel metering system of an internal combustion engine is controlled by a digital computer circuit which delivers injection pulses to actuate the fuel injection valve of the engine. The duration of these pulses is directly related to the amount of injected fuel and depends on the inherent characteristics of the engine as well as on the engine r.p.m. and the degree of throttle opening. A set of data points each of which correlates a fuel datum with a pair of numbers related to engine speed and throttle valve opening, respectively, is stored in a digital memory and can be addressed by digital signals from transducers associated with engine speed and throttle valve position. An arithmetic unit then performs an interpolation process by weighted addition of nearest neighbor values of the datum stored in the memory. The final, interpolated datum is counted down at constant or variable frequency and represents an output signal related to the fuel injection period.

Abstract: The operation of an internal combustion engine in the region of its lean-running limit is controlled on the basis of engine roughness as measured by an inductive crankshaft transducer. Its periodic signal gates the counting in a digital down-counter, from a pre-set number, at a frequency proportional to r.p.m. The content of the down counter is counted up or down in a subsequent up-down counter depending on the value of its own most significant bit which indicates the algebraic sign of the phase comparison between the transducer frequency and the r.p.m.-proportional frequency. Two digital integrating stages eliminate effects due to constant engine acceleration. A decoder supplies a control signal to a final control element for fuel, air or exhaust control.