AIRCRAFT STARTER CONTROL SYSTEM

• US 3,812,378 A
• Filed: 03/09/1972
• Issued: 05/21/1974
• Est. Priority Date: 03/09/1972
• Status: Expired due to Term

• Current Assignee: Parker Intangibles LLC (Parker-Hannifin Corporation)
• Original Assignee: William E. Coman
• Inventors: Coman, William E.
• Primary Examiner(s): Simmons, G. R.
• Application Number:
  US05/233,196
• Time in Patent Office: 803 Days
• Field of Search: 290/37,38 123/199A,179
• US Class Current: 290/38.00R
• CPC Class Codes: B64D 41/00 Power installations for auxiliary purposes
• CPC Class Codes: F02N 11/0848 with means for detecting successful engine start, e.g. to stop starter actuation

Abstract

A control system for automatically closing a solenoid-operated air valve that supplies pressurized air to rotate an air turbine starter motor of an aircraft engine when the starter rotor reaches a predetermined rotational speed. The control system senses rotation of the starter rotor and produces a pulse train wherein each of the pulses generated has a duration which is a function of the rotational speed of the starter rotor and compares each pulse duration to a reference pulse which corresponds to a predetermined rotational speed of the starter rotor. When the duration of the rotor pulses decreases to a point where they are shorter in duration than a reference pulse, the supply of pressurized air is removed from the starter, thereby removing power from the starter at the predetermined speed.

Claims

1. A starter control system for automatically de-energizing a circuit, which supplies power to said starter, when the starter rotor reaches a predetermined rotational speed, said control system comprising:

means for generating a first pulse train wherein each of said pulses generated has a duration D1 which is a function of the rotational speed of said starter rotor, said pulses decreasing in duration as the rotational speed of said rotor increases, said means for generating a first pulse train comprising;

a permanent magnet generator; and

a bistable circuit that initiates a pulse upon receiving a first impulse from said permanent magnet generator and terminates said pulse upon a second impulse from said permanent magnet generator;

means for generating a second pulse train wherein each of said pulses generated has a constant time duration D2 that corresponds to said predetermined rotational speed of said starter rotor at which said motor is to be de-energized; and

switching means for de-energizing the circuit that supplies power to said starter when the duration D1 of a pulse of said first pulse train is shorter than the duration D2 of a pulse of said second pulse train whereby the starter is automatically de-energized when said starter rotor reaches said predetermined rotational speed, said switching means comprising;

a first comparator circuit for receiving the pulses from said first pulse generator and said second pulse generator, said first comparator producing a first signal when the duration of a pulse from said first pulse generator is shorter in duration than a pulse from said second pulse generator; and

a transistorized switching circuit operable to remove electrical energy to said starter upon receipt of said first signal from said first comparator, circuit thereby de-energizing said starter.

2. The starter control system recited in Claim 1 wherein said permanent magnet generator also includes means for rectifying the pulses generated by said permanent magnet generator.

3. The starter control system recited in claim 1 wherein said switching means for de-energizing the circuit that supplies electrical energy to said starter further comprises:

a second comparator having means for receiving a signal from said first comparator and means for receiving a signal from said permanent magnet generator, said second comparator operative to produce an output signal when it receives said first signal from said first comparator and a signal from said generator; and

wherein said transistorized switching circuit conducts to apply electrical energy to said starter upon receipt of said output signal from said second comparator and is nonconductive to de-energize the circuit which supplies electrical energy to said starter in the absence of a first signal from said second comparator.

4. The starter control system recited in claim 3 wherein said second comparator comprises:

a first transistor having its base in electrical circuit relationship with the output of said first comparator;

a zener diode in circuit relationship with one other electrode of said first transistor and circuit relationship with the rectifying means of said permanent magnet generator; and

a silicon-controlled rectifier having its gate in electrical circuit relationship with said zener diode and one of its other electrodes in circuit relationship with the remaining electrode of said first transistor, said SCR being conductive when said first transistor is nonconductive and said zener diode is conductive, whereby said second comparator produces an output signal to turn off the transistorized switch and deenergize the starter.

5. In combination with an electric starting system for cranking an engine of the type having a source of electrical power, a starter motor, a solenoid and a mechanical switch for connecting the electrical power in circuit relationship with the solenoid, which, when energized, couples the starter motor to the engine and connects the electrical power to the starter motor to crank the engine, wherein the improvement comprises:

switching means for automatically de-energizing said solenoid when said starter rotor has reached a predetermined rotational speed, said means for de-energizing said solenoid further including;

means for generating a first pulse train wherein each of said pulses generated has a duration D1 which is a function of the rotational speed of said starter rotor;

means for generating a second pulse train wherein each of said pulses generated has a constant time duration D2 that corresponds to said predetermined speed of said starter rotor; and

means for de-energizing said solenoid when the duration D1 of a pulse of said first pulse train is shorter than the duration D2 of a pulse of said second pulse train whereby said starter motor is automatically decoupled from said engine when said starter rotor reaches said predetermined rotational speed.

6. The control system as recited in claim 5 wherein said means for de-energizing said solenoid includes a transistor switch, in series electrical relationship with said solenoid, that is conducting ON when D1 is greater than D2 and is nonconducting OFF when D1 is less than D2.

7. The control system as recited in claim 5 wherein said means for generating said first pulse train includes a permanent magnet generator and a bistable multivibrator.

8. The control system as recited in claim 6 wherein said means for generating said first pulse train includes a permanent magnet generator and a bistable multivibrator.

9. The control system as recited in claim 6 including a full wave rectifier bridge having its output terminals connected to the collector and emitter electrodes of said transistor switch and its input terminals connected in series with saId source of electrical power so that said transistor switch is operable regardless of the direction that current flows through said solenoid.

10. A control system for automatically closing a solenoid operated air valve that supplies pressurized air to rotate an air turbine starter motor of an engine, when the starter rotor reaches a predetermined rotational speed, said control system comprising:

means for sensing the rotational speed of said starter rotor and generating a first pulse train wherein each of said pulses generated has a duration D1 which is a function of the rotational speed of said starter rotor;

means for generating a second pulse train wherein each of said pulses generated has a constant time duration D2 that corresponds to said predetermined rotational speed of said starter rotor; and

means for closing the solenoid operated air valve when the duration D1 of a pulse of said first pulse train is shorter than the duration D2 of a pulse of said second pulse train whereby said supply of presusrized air is removed from said starter when said starter rotor reaches said predetermined rotational speed.

11. The control system as recited in claim 10 including a d-c power supply for supplying power to said solenoid and wherein said means for closing the solenoid operated air valve includes a transistor switch and a full wave rectifier bridge in circuit relationship with said power supply to control the power applied to said solenoid, said transistor switch having its emitter and collector terminals connected to the output of said bridge, said rectifier bridge having two input leads connectable in series to said d-c power supply whereby said transistor switch is operable to permit current to flow into said solenoid from said d-c supply when either lead of said bridge is connected to the positive side of said d-c power supply and the remaining lead of said bridge is connected to said negative side of said d-c power supply.

12. A control system as recited in claim 10 wherein the means for generating a first pulse train is a permanent magnet generator.

13. The control system as recited in claim 10 wherein said means for generating a first pulse train includes a bistable circuit that initiates a pulse upon receiving a first impulse from said permanent magnet generator and terminates said pulse upon a second impulse from said generator.

14. The control system as recited in claim 12 wherein said means for generating a first pulse train includes a bistable circuit that initiates a pulse upon receiving a first impulse from said permanent magnet generator and terminates said pulse upon receiving a second impulse from said permanent magnet generator.

15. The control system as recited in claim 13 wherein said means for closing the solenoid operated air valve includes a comparator that compares the duration of a pulse from said bistable to the duration of a pulse from said second pulse train generator and provides an output signal when the duration of the pulse from said bistable is shorter than the duration of said pulse from said second pulse train generator.

16. The control system as recited in claim 14 wherein said means for closing the solenoid operated air valve includes a comparator that compares the duration of a pulse from said bistable to the duration of a pulse from said second pulse train generator and provides an output signal when the duration of the pulse from said bistable is shorter than the duration of said pulse from said second pulse train generator.

17. The control system as recited in claim 10 wherein said means for closing the solenoid operated air valve includes a transistorized switch in series electrical relationship with said solenoid and the power supplied to the solenoid so that when said transistorized switch is open, said solenoid is de-energized whereby said valve is closed thereby removing the supply of pressurized air that rotates said starter motor.

18. The control system as rEcited in claim 11 wherein said means for closing the solenoid operated air valve includes a transistorized switch in series electrical relationship with said solenoid and the power supplied to the solenoid so that when said transistorized switch is open, said solenoid is de-energized whereby said valve is closed thereby removing the supply of pressurized air that rotates said starter motor.

19. The control system as recited in claim 12 wherein said means for closing the solenoid operated air valve includes a transistorized switch in series electrical relationship with said solenoid and the power supplied to the solenoid so that when said transistorized switch is open, said solenoid is de-energized whereby said valve is closed thereby removing the supply of pressurized air that rotates said starter motor.

20. The control system as recited in claim 14 wherein said means for closing the solenoid operated air valve includes a transistorized switch in series electrical relationship with said solenoid and the power supplied to the solenoid so that when said transistorized switch is open, said solenoid is de-energized whereby said valve is closed thereby removing the supply of pressurized air that rotates said starter motor.

21. The control system as recited in claim 15 wherein said means for closing the solenoid operated air valve includes a transistorized switch in series electrical relationship with said solenoid and the power supplied to the solenoid so that when said transistorized switch is open, said solenoid is de-energized whereby said valve is closed thereby removing the supply of pressurized air that rotates said starter motor.

22. A control system for de-energizing a circuit, said control system comprising:

a first circuit which includes;

a first source of electrical energy;

a reactive circuit element in series circuit relationship with said first source of electrical energy;

a first switch connected in series circuit relationship with said source of electrical energy and said reactive circuit element, said switch operable upon closing to apply electrical energy to said reactive circuit element; and

a transistor switch in series circuit relationship with said reactive circuit element, said transistor switch operable upon closing of said first switch to permit electrical energy to be supplied to said reactive circuit element, said transistor switch including a passive circuit element in circuit relationship with said transistor and having a voltage applied thereto from said first source upon closing of said first switch which forward biases said transistor so that said transistor is conductive (ON);

a second circuit which includes;

an electromagnetic source of electrical energy separate from said first source of electrical energy for producing pulses which vary in duration as a function of a determinable parameter of said electromagnetic device, and including a permanent magnet generator having a rotor and stator element, said generator generating electrical energy levels which are proportional to the rotational speed of the generator;

the reactive circuit element being the winding of an electromechanical device that controls power to a starter motor and said permanent magnet generator being mechanically linked to said starter motor; and

a second solid state switching circuit in circuit relationship with said passive circuit element of said first circuit and said electromagnetic source of electrical energy, said second switch operable to apply a reverse voltage across said passive circuit element when said electromagnetic source of electrical energy produces a pulse having a predetermined duration whereby said first transistor switch is reverse biased rendering said first transistor switch nonconductive, thereby de-energizing said first circuit.

23. A control system as recited in claim 22 wherein the reactive circuit element is the winding of an electromechanical device and wherein said electromagnetic source of electrical energy is mechanically linked to said electromechanical device.

24. A starter control system for automatically de-energizing a circuit, which supplies power to said starter, when the starter rotor reaches a predetermined rotational speed, said control system comprising:

means for generating a first pulse train wherein each of said pulses generates has a duration D1 which is a function of the rotational speed of said starter rotor, said pulses decreasing in duration as the rotational speed of said rotor increases, said means for generating a first pulse train including;

a permanent magnet generator;

means for generating a second pulse train wherein each of said pulses generated has a constant time duration D2 that corresponds to said predetermined rotational speed of said starter rotor at which said motor is to be de-energized; and

switching means for de-energizing the circuit that supplies power to said starter when the duration D1 of a pulse of said first pulse train is shorter than the duration D2 of a pulse of said second pulse train whereby the starter is automatically de-energized when said starter rotor reaches said predetermined rotational speed, said switching means for de-energizing the circuit that supplies electrical energy to said starter comprising;

a transistorized switching circuit that includes at least one transistor, said transistor allowing electrical energy to be supplied to said starter in the conducting state and preventing electrical energy from being supplied to said starter in the nonconducting state; and

a comparator means for receiving pulses from said first pulse generator, pulses from said second pulse generator, and a voltage signal from said permanent magnet generator, said comparator means operable to produce an output signal upon receipt of a voltage signal of predetermined magnitude from said generator and a pulse from said first pulse generating means having a duration greater than a pulse from said second pulse generating means, said output signal coupled to said transistor switch to render said transistor conductive, whereby electrical energy is supplied to said starter when said transistor conducts and when said signal from said comparator means is removed, said transistor switch is nonconductive and said starter is de-energized.