Motorola Corporation

Howard F Weber

Robert B Jarrett

David L Cave

Wilson D Pace

Mark L Shaw

Jack R Morgan

Gary L Maulding

An ignition system which is responsive to timing signals generated in timed relationship to the operation of an internal combustion engine for providing firing spark to operate the engine. The system uses two capacitors to provide an adaptive dwell system wherein the percent of time that ignition coil current is limited at a fixed magnitude is made variable with respect to the engine rpm.

Ignition system having variable percentage current limiting

A driver circuit is coupled to the stator windings of a brushless three phase DC motor which is responsive to the open circuit back EMF voltage induced in the next stator winding to be energized as a permanent magnet rotor of the motor is caused to be rotated for producing phase current drive to the stator winding in synchronous with the operation of the motor. The driver circuit includes an increment drive circuit for supplying periodic switching command signals in succession to a switching circuit to produce phase current drive in each stator. The increment drive circuit increments a switch command signal to cause phase current through the next phase stator winding in reference to the magnitude of the EMF voltage induced across said phase stator winding falling below a reference level. A feature of the invention is that the frequency of the periodic switch command signals is varied during starting of the motor dependent on the magnitude of starting potential supplied to the driver circuit to prevent the motor from 'locking' which would otherwise inhibit start thereof.

Brushless three phase direct current motor control circuit

The self-protecting load driver circuit includes an output transistor having an emitter coupled to a current sensor and a collector adapted to be coupled to the electrical load. A comparator senses the magnitude of a current sensor signal and applies trigger signals to a time delay circuit which is connected between the output of the comparator and the control terminal of a control circuit for the protected transistor. The rise time of the voltage across the current sensor depends on the inductance, for instance, of the load. The time delay circuit enables the control circuit to disable the output transistor for a predetermined time duration in response to the threshold voltage of the comparator being exceeded by the sensor voltage. At other times, the protected transistor is saturated by the control circuit so that power is delivered to the load.

Inductive load driver protection circuits having minimal power

A circuit to be utilized in combination with an ignition system which is responsive to a start signal supplied thereto for maintaining the ignition system in a start mode of operation while starting of the internal combustion engine is controlled by the ignition system. The circuit is responsive to termination of the start signal to provide transitioning of the ignition system to a run mode of operation only during the current ramping period when the ignition coil of the ignition system is being charged prior to the end of a firing cycle when the coil is discharged to provide spark to operate the engine. Start retard and transitioning of the system from start to run modes is provided utilizing a single capacitor.

Start-to-run circuit for an electronic ignition system

A cruise control system having means to provide a signal corresponding to a desired speed for use by a servo control to regulate the speed. This system uses a current source to ramp charge a first capacitor. A comparator compares magnitude of the voltage on the first capacitor against the signal representative of the desired speed. A first counter is used to accumulate counts from a first frequency generator. A latch counter capable of following the counts in the first counter is used to store the counts when the comparator indicates the voltage on the first capacitor is substantially equal to the magnitude of the signal representative of the speed. A digital comparator then compares the counts stored in the latch counter against counts being accumulated anew in the first counter while the first capacitor is being recharged. Means are provided to inhibit the first capacitor from being charged further after the digital comparator indicates equality between the quantity of the counts being compared. Means to transfer the voltage on the first capacitor to a second capacitor are used so that the voltage on the second capacitor can be compared against the signal representative of the actual speed which then provides an output to the servo control to regulate the speed.

Cruise control method and apparatus

A digital speed control system includes a first binary up-counter called an Actual Count Register. The Actual Count Register is initially reset to contain all '0''s. During a sample time, an input is applied to the Actual Count Register so that it counts up to a first binary number during the sample time. The first binary number represents a reference speed. The system includes a Reference Count Register. In response to read and store command, the first binary number is loaded into the Reference Count Register, where it remains until the next request for a new reference speed. The system further includes a first binary presettable up-counter called the Error Register. The Error Register counts up at the same rate and in response to the same count signal as the Actual Count Register. During a Transfer signal which follows the Read signal, the complement of the first binary number is transferred from the Reference Count Register into the Error Register. The system also includes a second binary presettable up-counter called an Acceleration Register. The inputs of the Acceleration Register are coupled to the outputs of the Actual Count Register so that during the transfer signal the complement of the first binary number is loaded into the Acceleration Register. A decoder connected to the outputs of the Error Register interprets its contents, and a second decoder interprets the contents of the Acceleration Register.

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Scottsdale, AZ, United States of America

Howard F Weber