Abstract: A circuit is described for energizing an electromagnetically operated fuel injector from an unregulated voltage source in response to an injection command pulse. The injector pull-in current is provided by directly coupling the unregulated voltage across the injector upon the initiation of the injection command pulse. The injector current is thereafter reduced to a lower hold-in value. The circuit is voltage compensated by a pair of timers the first of which compensates for the voltage dependent injector pull-in time by adjusting the time that the unregulated voltage is directly applied across the injector as a function of the value of the unregulated voltage to insure that the injector is energized for all values of the unregulated voltage while minimizing the time period that the unregulated voltage is directly coupled across the fuel injector.

Abstract: A closed loop fuel control system is described for a vehicle internal combustion engine which includes an exhaust gas sensor providing a signal having a value determined by the oxidizing/reducing conditions of the exhaust gases. An integral controller is responsive to the output of the exhaust gas sensor and provides a control signal varying in a first direction for sensed oxidizing/reducing conditions greater than a desired condition and varying in an opposite direction for sensed oxidizing/reducing conditions less than the desired condition. A control circuit is responsive to the output of the integral controller to adjust the vehicle engine air/fuel supply device to vary the value of the air/fuel ratio of the mixture supplied to the engine in a direction tending to maintain the desired exhaust gas condition. The output of the integral controller is limited to predetermined values so as to limit the air/fuel ratio control authority of the closed loop circuit.

Abstract: A closed loop fuel control system is described for an internal combustion engine having two cylinder banks and an air/fuel mixture supply means for supplying a combustible mixture to each of the cylinder banks with the air/fuel ratio of the mixture supplied to each of the cylinder banks having relative values determined by the characteristics of the engine and the mixture supply means. Two exhaust gas sensors are provided, each being located at the exhaust discharge point of a respective one of the cylinder banks and sensing the oxidizing/reducing conditions of the exhaust gases from the respective cylinder bank. A controller adjusts the air/fuel mixture supply means to obtain a specified air/fuel ratio in response to combinations of exhaust gas oxidizing/reducing conditions as sensed by the exhaust gas sensors.

Abstract: A three phase AC to DC voltage converter includes separate single phase AC to DC converters for each phase of a three phase source with the DC voltage output of the three converters paralleled and controlled to provide necessary regulation. Each of the single phase AC to DC converters includes a full-wave bridge rectifier feeding a substantially resistive load including an inverter and a second single phase full-wave bridge rectifier. To the extent that each inverter and second single phase full-wave bridge rectifier approximate a resistive load, the source current harmonics are reduced. Additionally, the triplen harmonics produced in the three phase source lines by each of the three AC to DC converters are cancelled by the triplen harmonics produced in the three phase source lines by the remaining two AC to DC converters.

Abstract: A memory type fuel control system and method of operating a motor vehicle internal combustion engine having a three-way catalytic converter. A fuel flow control system provides a fuel supply rate near the air/fuel ratio at which the catalytic converter has maximum three-way conversion efficiency. The fuel supply rate so determined is trimmed by a trim factor recalled from memory, the authority of this trim factor being sufficient to compensate for engine and controller variations with time, manufacturing tolerances, etc. In the preferred form, the trim factor is stored in memory at an address determined by the same engine operating conditions that control the fuel supply. The engine exhaust gas oxidizing/reducing conditions are sensed by exhaust gas sensors.

Abstract: A system is described for controlling the movement of a vehicle over a guideway having a specified length. A signal is generated which represents a commanded absolute position of the vehicle on the guideway. A vehicle position transducer provides a signal having a value representing the actual position of the vehicle on the guideway which is compared with the commanded position to provide a position error signal. The speed of the vehicle is controlled in accord with the value of the position error signal. The commanded vehicle position signal is varied with time in a manner to provide desired vehicle motion characteristics including vehicle jerk and acceleration and deceleration values. The system also provides for a constant velocity control mode.

Abstract: A digital closed loop fuel control system for an internal combustion engine having a zirconia sensor which provides a signal changing abruptly between first and second values as the air/fuel ratio varies through a stoichiometric ratio. The output of the zirconia sensor is sampled at constant frequency sampling intervals and an up/down counter is set in one of its counting modes as a function of whether the air/fuel ratio is less than or greater than the stoichiometric ratio. During each sampling interval, a first number of clock pulses from a clock pulse generator are coupled to the up/down counter when the air/fuel ratio is greater than a stoichiometric ratio and a second number of the clock pulses are coupled to the up/down counter when the air/fuel ratio is less than the stoichiometric ratio.

Abstract: A circuit for energizing a fuel injector valve coil in response to a fuel injection pulse including a storage capacitor which is charged from a relatively high voltage source and which is discharged through the fuel injector valve coil through a controlled rectifier gated conductive upon the initiation of a fuel injection pulse signal. The charging circuit for the capacitor is disabled upon initiation of capacitor discharge for a time period at least greater than the time for the capacitor discharge current to decrease to a value to effect commutation of the controlled rectifier after which capacitor charging is reinitiated. A holding circuit is provided for holding the fuel injector valve coil energized for the duration of the fuel injection pulse signal.

Abstract: A wheel lock control circuit includes a deceleration switch which effects release of the vehicle brake pressure when the deceleration of the vehicle wheels are greater than a reference deceleration. A portion of the reference deceleration is provided by an adaptive control circuit which is responsive to wheel deceleration to supply a signal representing an estimate of vehicle deceleration. An initial cycle circuit provides an initial high level portion of the reference deceleration to desensitize the system to noise signals and wheel transients. The initial cycle output of the initial cycle circuit is controlled by a portion of the adaptive control circuit which is responsive to wheel deceleration and which has a time constant greater than the deceleration switch so that the initial cycle circuit is effective to desensitize the wheel lock control circuit to system noise and vehicle transients independent of the deceleration switch response to the acceleration and reference signals.

Abstract: An apparatus for providing an output digital signal when the magnitude of a monitored parameter is within a critical range. An oscillator repeatedly charges each of first and second capacitors to a predetermined voltage level. A monitoring resistor is parallel coupled with the first capacitor and has a resistance progressively changing with the magnitude of the parameter to define a rate of discharge of the first capacitor, between repeated chargings, determined by the parameter. A reference resistor is parallel coupled with the second capacitor and has a resistance equal to the resistance of the monitoring resistor when the magnitude of the monitored parameter is at the threshold of the critical range and defines a first reference rate of discharge of the second capacitor between repeated chargings. The voltages across the first and second capacitors are monitored by respective threshold detectors, each of which provides an output when the voltage across the respective capacitor exceeds a specified level.

Abstract: A transducer for producing a pulse duration modulated signal in accord with the value of a parameter. A reference capacitor-resistance circuit is provided having a predetermined rate of capacitor discharge and a second capacitor-resistance circuit is provided having a capacitor and a resistor, one of which is varied in accordance with the parameter to define a rate of capacitor discharge determined by the parameter. Each of the capacitors is periodically charged in unison to a predetermined voltage. Respective level detectors monitor the capacitor voltage charges and generate respective digital signals when the voltage charge monitored is greater than a predetermined reference below which each capacitor discharges during the time interval between charges. A logic circuit monitors the digital signals and produces a series of pulses having durations determined by the value of the parameter.

Abstract: An electronic channel selector is described for providing a tuning signal at a frequency corresponding to a selected channel. A logic circuit cooperates with an uncoded rotary switch for providing control signals to an up/down counter which counts up or down in response to rotation of a rotary switch in a clockwise or counterclockwise direction and which provides a digital signal representing a selected channel. The digital signal from the up/down counter controls a channel display and frequency synthesizer.

Abstract: A stereo noise reduction circuit is disclosed having circuitry responsive to the automatic gain control voltage generated within an FM stereo receiver for reducing the noise associated with low levels of the RF carrier. A first portion of the noise reduction circuit provides for out-of-phase noise cancellation when the automatic gain control voltage reaches a first level and a second portion provides for rolling-off the higher frequencies of the output audio signals when the automatic gain control voltage reaches a second level.

Abstract: A wheel lock control system for a vehicle is described that is responsive to wheel speed to provide a brake release signal when the wheel speed signal characteristics represent an incipient wheel lock condition. The braking forces on the vehicle wheels are relieved by the wheel lock control system for the duration of the brake release signal. A monitoring circuit monitors selected system parameters and provides a fault signal while the parameters represent a fault condition.

Abstract: A wheel lock control system for cyclically releasing and applying the wheel brakes to prevent wheel lock during braking. A deceleration switch produces a control signal to effect a wheel brake release when the wheel speed exceeds a predetermined deceleration threshold representing an incipient wheel lock condition. A cycle depth integrator provides a cycle depth signal that is representative of the magnitude of the change of wheel speed after a brake release. A cycle depth comparator is responsive to the control signal and the cycle depth signal to effect wheel brake release during the control signal and to maintain the wheel brake release as a function of the cycle depth signal magnitude and duration and wheel speed characteristics to provide for adaptation to all vehicle and road conditions.

Abstract: A voltage variable capacitor tuned radio receiver having a circuit which delays operation of a portion of the radio receiver circuit which includes the automatic frequency control circuit after the radio receiver is first energized until the filter capacitor at the output of the tuning voltage generator has charged to a selected tuning voltage to prevent the automatic frequency control circuit from locking the radio receiver onto an undesired RF carrier frequency.

Abstract: A protection circuit for a bridge audio power amplifier having two pairs of output transistors coupled between positive and negative terminals of a direct current supply and providing a pair of output terminals for connection across a load. The bias of the output transistors are controlled in response to excessive current flow, a short of the output terminals to ground, excessive DC supply voltage, a short of the output terminals to the positive terminal of the DC supply, and excessive temperature to prevent permanent damage to the bridge audio power amplifier.

Abstract: An anti-lock brake control circuit compares the deceleration of a braked wheel with a deceleration reference and integrates the difference when wheel deceleration exceeds the reference deceleration. A resulting velocity error signal is compared with a velocity error reference and a release signal is generated while the velocity error signal exceeds the velocity error reference. Adaptive control is provided by a first order lag circuit having wheel velocity as its input and which supplies a variable portion of the deceleration reference having a slope approximately equal to the slope of the vehicle velocity profile during braking on low coefficient surfaces and having a slope less than the slope of the vehicle velocity profile during braking on high coefficient surfaces. An initial cycle and pulse circuit sets the velocity error reference to a high level for both the first cycle of anti-lock brake operation and for a time period after each brake application during anti-lock brake operation.

Abstract: A controlled rectifier resonant bridge inverter having its operating frequency varied to maintain a regulated voltage supplied to a load. The inverter has a commutating circuit having a first resonant frequency defining a maximum inverter operating frequency during normal load conditions and a second higher resonant frequency defining a higher maximum inverter operating frequency during short circuit load conditions to provide reliable inverter operation for all load conditions including a short circuit load condition.

Abstract: A radar system provides a measurement of the co-linear and cross-polarization characteristics of a radar target. Vertically and horizontally polarized RF signals are selectively transmitted to a target and the co-linear and cross-polarized RF returns from the target are detected with each return being coupled to an output switch which is selectively operated to provide an output RF signal for providing either the co-linear or cross-polarized RF return. RF null circuits are provided for nulling internal system RF reflections for both co-linear and cross-polarized returns when either polarized signal is transmitted.