US2443648A - Starting means for gas turbines - Google Patents

Description

June 22, 1948. us N r 2,443,648

STARTING MEANS FOR GAS TURBINES Filed Feb. 5, 1947 and Og z ar C. Wa/Ieg.

Patented June 22, 1948 STARTING MEANS FOR GAS TURBINES Bascum 0. Austin and Omar C. Walley, Lima,

Ohio, assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 1947, Serial No. 726,670

16 Claims. 1

The present invention relates to starting means for gas turbines, and, more particularly, to control means for the starting motor and the ignition circuit of a gas turbine.

Gas turbines are not self-startin and they must be started by some external means, usually an electric motor which drives the turbine until it starts to run independently. It is also necessary to ignite the fuel of the gas turbine at the same time the starting motor is started, and this is frequently done by means of an electric ignition circuit, which is energized simultaneously with the starting motor. tion of the ignition circuit must, of course, be maintained for a lon enough time to insure that the fuel is ignited, and that combustion has been well established.

The principal object of the present invention is to provide a simple and reliable starting means for gas turbines.

Another object of the invention is to provide control means for startin a gas turbine, in which the starting motor and the ignition circuit are substantially simultaneously energized, and in which the motor is deenergized when the turbine starts to run, or when it reaches a predetermined speed, while the ignition circuit is deenergized after a predetermined time interval.

A further object of the invention is to provide control means for starting a gas turbine, in which the starting motor and the ignition circuit are energized substantially simultaneously, and in which all parts of the starting system are automatically deenergized at the end of a predetermined time interval, so that the system operates in definite time cycles.

A still further object of the invention is to provide control means for an electric motor and for an associated auxiliary circuit, in which the motor and the auxiliary circuit are energized substantially simultaneously, the motor is deenergized in response to a predetermined load condition, and the auxiliary circuit and motor are both deenergized at the end of a predetermined time interval. This system is especially adapted for use in controlling the starting motor and isnition circuit of a gas turbine, but in its broader aspects, its usefulness is not necessarily restricted to this particular application.

The invention will be more fully understood from the following detailed description, taken in connection with the accompanying drawing, the single figure of which is a schematic diagram showing a preferred embodiment of the invention.

The drawing shows a starting means for a. gas

The energiza- I turbine I, which has been shown diagrammatically, and which may be of any desired construction. The gas turbine lis started by means of an electric motor 2, which is adapted to be mechanically connected to the turbine in any suitable manner to drive it until it has started. The motor 2 is shown as a direct-current series motor, havin a field winding 3 connected in series with the armature, although other types of motors might also be used. The gas turbine has an "electric ignition circuit 4 for the purpose of igniting the fuel. The ignition circuit 4 may include any suitable type of igniting device in the combustion chamber of the gas turbine l, and the circuit is completed by a connection to ground at 5.

The starting motor 2 may be supplied from any suitable source of electric energy. The particular embodiment of the invention shown in the drawin is intended for aircraft use, and a battery 6 is utilized as the source of electric energy. One terminal of the battery 5 is connected to supply the motor 2 through a con-' ductor I, and the other terminal of the battery is grounded at 8. The motor 2 is controlled by means of a contactor 9, which has an operating coil l0 and a main contact. II. The contactor is arranged so that when the coil I0 is energized, the contact H of the contactor closes to connect one terminal of the motor 2 to the conductor 1, the :ther terminal of the motor being grounded at l Operation of the contactor 9 is controlled by means of a normally-open push button I3 and a current-responsive relay M. The relay [4 has a normally open contact l5 connected in parallel with the push button l3, and an operating coil l6 connected in series with the motor 2 so as to carry the motor current. The relay I4 is designed so that when the coil I6 is energized by the starting current of the motor 2, it will cause the contact 15 to close, and will hold it closed until the motor current decreases to a value corresponding to a predetermined load on the motor, or a predetermined motor speed. When the current has dropped to this value, the relay l4 drops out and opens the contact l5. One end of the operating coil W of the contactor 9 is connected to ground at H, and the other end is connected to a control circuit l8 by means of the push button l3 or the contact IS.

The control circuit I8 is supplied from any suitable source of electric energy, which may be the battery 6, as shown, through a normally closed contact I9. As indicated above, the control circuit l8 supplies the operating coil I of the contactor 9. The control circuit I8 is also utilized to energize the ignition circuit 4 of the gas turbine I. For this purpose, the contactor 9 has an auxiliary contact 20, which is arranged to close when the main contact closes. auxiliary contact 20 is connected between the control circuit i8 and the ignition circuit 4, so that the ignition circuit is energized when the contact 26 closes.

There is also provided a timing motor 2|, which may be any suitable type of small, substantially constant-speed motor, and which is shown as a direct-current shunt motor, having a field winding 22 connected across the motor terminals.

One terminal of the motor 2| is connected to ground at 23, and the other terminal is connected to the contact 20, so that the motor is energized from the control circuit I8 when the contact .20 closes. The timing motor 2| is provided with an electrically operated clutch as. of any suitable type, which has an operating coil 25 connected in parallel with the motor 2|, and which is arranged to be engaged when the coil 25 is energized. An auxiliary contact 25 is provided on the clutch 2d, and is arranged to close when the clutch 28 is engaged. The auxiliary contact 26 is connected in parallel with the contact 20. The clutch 24 connects the timin motor 2| to a gear train 27, which drives a cam 28, or other suitable operating device, which actuates the contact I9 to open position after the timing motor 2| has been in operation for a predetermined length of time, determined by the gear train :27, or by adjustment of the cam 28.

In the operation of thls'system, when it is desired to start the gas turbine I, the push button i3 is depressed to connect the coil it of the contactor 9 to the control circuit it. Since the contact I9 is normally closed, the coil H] is energized when the push button I3 is depressed,

and the contactor 9 closes its main contact II and auxiliary contact 20. Closing of the main contact connects the motor 2 to the battery 6, and the motor starts, driving the gas turbine I. When the motor starts, the current through the coil N5 of the relay IE causes it to pick up and close its contact l5, so that energization of the coil I0 is maintained, and the push button I3 can be released as soon as the motor 2 starts.

Simultaneously with the starting of the motor 2, the ignition circuit 4 is energized from the control circuit l8 through the auxiliary contact 20 on the contactor 9. Closing of the contact 20 also connects the timing motor 2i and clutch coil 25 to the control circuit, so that the tim- Theing motor 2| starts to run and the clutch 2c is engaged to cause the timing motor 2| to drive the cam 28 through the gear train 21. When the clutch 24 engages, the auxiliary contact 26 closes, paralleling the contact 20, and connecting the timing motor and clutch coil directly to the control circuit l8.

As the starting motor 2 brings the gas turbine I up towards its normal speed, the load decreases, and the motor current decreases, and when the current has decreased to a predetermined value, which may correspond to a motor speed at which the gas turbine i would normally have started self-sustaining operation, or to any other desired load condition, the relay |4 drops out, opening its contact l5. This deenergizes the coil ill, and the contactor 9 opens its contacts H and 20, disconnecting the motor 2 from the battery, so that the motor stops. The contact 26 remains closed,

energized, and the timing motor 2| continues to run. Thus, energization of the ignition circuit is maintained to insure that combustion of the fuel will be well established.

At the end of a predetermined time interval, the cam 28, which is driven by the timing motor 2|, actuates the contact I9 to open it and interrupt the control circuit 8, which deenergizes the ignition circuit a, the timing motor 2|, and the clutch coil 25. This stops the timing motor, and disengages the clutch 25, which causes the contact 25 to open; In case themotor 2 is still running at this time, the coil It will also be deenergized, causing the contactor 9 to open the contact I! and stop the motor. Thus, all parts of the system are automatically deenergized at the end of a definite predetermined time.

interval. The cam 28, or other actuating device, is arranged so that the contact I9 is opened only momentarily, and then recloses in readiness for another cycle of operation oi? the system.

If the gas turbine I has not yet started when the contact lt opens, the push button i3 is again depressed and the same cycle is repeated. If desired, the push button It can, of course, simply be held down until the turbine starts, the system going through repeated timed cycles of definite duration, as described above.

It will be apparent, therefore, that a starting control for gas turbines has been provided which is simple and reliable, and which effectively .performs the functions of energizing the starting motor and ignition circuit substantially simultaneously, of stopping the motor as soon as the gas turbine has started, or has accelerated to a predetern'iined speed, and of deenergizing the ignition circuit and all other parts of the system automatically at the end of a predetermined time.

A particular embodiment of the invention has been shown and described for the purpose of illustration, but it will be understood that various changes and modifications may be made within the scope of the invention. Thus, the system shown and described is especially adapted for aircraft use, and is, therefore, shown as utilizing a battery, and a ground return circuit, but it will be apparent that any other source of energy might be used, and that a wire return circuit might be utilized. It is to be understood, therefore, that the invention is not restricted to the particular details shown and described, but in its broadest aspects, it includes all equivalent modifications and embodiments which come within the scope of the appended claims.

We claim as our invention:

1. Control means for an electric motor and for an associated auxiliary circuit, said control means comprising means for effecting connection of said motor to a source of electric energy, means for substantially simultaneously energizing said auxiliary circuit, means for efiecting deenergization of the motor in response to a decrease in the current to the motor, and means for effecting deenergization of the motor and of theauxlliary ciring means being started in operation simultaneously with theenergization of the auxiliary circuit and being adapted to effect decnergization of the motor and or the auxiliary circuit at the end of a predetermined time.

3. Control means for an electric motorjand for an associated auxiliary circuit, said control means comprising means for effecting connection of said motor to a source of electric energy and for substantially simultaneously energizing said auxiliary circuit, means for effecting deenergization of the motor in response to a decrease in the current to the motor, means for maintaining energization of the auxiliary circuit, and timing means for effecting deenergization oi. the motor and of the auxiliary circuit at the end of a predetermined time.

4. Control means for an electric motor and for an associated auxiliary circuit, said control means comprising means ior eifecting connection of said motor to a source of electric energy and for substantially simultaneously energizing said auxiliary circuit, means for eilecting deenergization of the motor in response to a decrease in the current to the motor, contact means for maintaining energization of the auxiliary circuit independently'of the motor-energizing means, and timing means for effecting deenergization of the motor and or the auxiliary circuit at the end of a predetermined time.

5. Control means for an electric motor and fior an associated auxiliary circuit, said control means comprising means for efiecting connection of said motor to a source of electric energy and for substantially simultaneously energizing said auxiliary circuit, means for effecting deenergization of the motor in response to a decrease in the current to the motor, contact means for maintain= ing energization of the auxiliary circuit independently of the motor-energizing means, said contact means being actuated to closed position simultaneously with energization of the auxiliary circuit, and timing means'for effecting deenergization of the motor and of the auxiliary circuit at the end of a predetermined time.

6. Control means for an electric motor and for an associated auxiliary circuit, said control means comprising means for efiecting connection of said motor to a source of electric energy and for substantially simultaneously energizing said auxiliary circuit, means for effecting deenergization of the motor in response to a decrease in the current to the motor, contact means for maintaining energization of the auxiliary circuit independently of the motor-energizing means, and timing means, said contact means being actuated to closed position and said timing means being started in operation substantially simultaneously with energization of the auxiliary circuit, the timing means being adapted to effect deenergization of the motor and of the auxiliary.

circuit at the end of a predetermined time.

7. Control means for an electric motor and for an associated auxiliary circuit, said control means comprising a contactor for connecting said motor to a source of electric energy, manual means for effecting operation of said contactor to closed position, means responsive to the motor current for maintaining the contactor in closed position, said current-responsive means being adapted to cause the contactor to open when the motor current decreases below a predetermined value, means associated with the contactor for energizing the auxiliary circuit substantially simultane- Ously with the energization of the motor, contact means for maintaining energization of the auxiliary circuit independently of the contactor, and timing means, said contact means being actuated to closed position and said timing means being started in operation simultaneously with energization of the auxiliary circuit, the timing means being adapted to efiect deenergization of the motor and of the auxiliary circuit at the end of a predetermined time.

8. Control means for an electric motor and for an associated auxiliary circuit, said control means comprising a contactor for connecting said motor to a source of electric energy, a control circuit, manual means for energizing said contactor from the control circuit to cause the contactor to move to closed position, means responsive to the motor current for maintaining energization of the contactor, said current-responsive means being adapted to effect deenergization of the contactor when the motor current decreases below a predetermined value, means associated with the contactor for connecting said auxiliary circuit to the control circuit to be energized thereby when the contactor closes, contact means for maintaining energization of the auxiliary circuit independently of the contactor, said contact means being actuated to closed position simultaneously with energization of the auxiliary circuit, and timing means for effecting interruption or the control circuit at the end of a predetermined time after the contactor closes.

9. Control means for an electric motor and for an associated auxiliary circuit, said control means comprising a contactor for connecting said motor to a source of electric energy, a control circuit, manual means for energizing said contactor from the control circuit to cause the contactor to move to closed position, means responsive to the motor current for maintaining energization of the contactor, said current-responsive means being adapted to effect deenergization of the contactor when the motor current decreases below a predetermined value, means associated with the contactor for connecting said auxiliary circuit to the control circuit to be energized thereby when the contactor closes, contact means for maintaining energization of the auxiliary circuit independently of the contactor, and timing means, said contact means being actuated to closed position and said timing means being started in operation simultaneously with energization of the auxiliary circuit, the timing means being adapted to effect interruption of the control circuit at the end of a predetermined time.

10. Control means for an electric motor and for an associated auxiliary circuit, said control means comprising a contactor for connecting said motor to a source of electric energy, a control circuit, manual means for energizing said contactor from the control circuit to cause the contactor to move to closed position, means responsive to the motor current; for maintaining energization of the contactor, said current-responsive means being adapted to effect deenergization of the contactor when the motor current decreases below a predetermined value, means associated with the contactor for connecting said auxiliary circuit to the control circuit to be energized thereby when the contactor closes, contact means for maintaining energization of the auxiliary circuit independently of the contactor, said contact means being actuated to closed position simultaneously with energization of the auxiliary circuit, and a timing motor, said timing motor being connected to the control circuit simultaneously with ener- 'gization of the auxiliary circuit, said contact means being adapted to maintain energizaticn of the timing motor, and the timing motor being adapted to effect interruption of the control circuit at the end of a'predetermined time.

11. Starting means for a gas turbine which includes an electric ignition circuit, said starting means comprising an electric motor adapted to be connected to the gas turbine for starting it, means for eflecting connection of said motor to a source of electric energy, means for substantially simultaneously energizing said ignition circuit, means for efiecting deenergization of the motor in response to a decrease in the load on the motor, and means for effecting deenergization of the motor and of the ignition circuit at the end of a predetermined time.

12. Starting means for a, gas turbine which includes an electric ignition circuit, said starting means comprising an electric motor adapted tobe connected to the gas turbine for starting it, means for effecting connection of said motor to a source of electric energy, means for substantially simultaneously energizing said ignition circuit, means for effecting deenergization of the motor in response to a decrease in the load on the motor, means for maintaining energization of the ignition circuit independently of energization of the motor, and timing meansfor effecting deenergization of the motor and of the ignition circuit at the end of a predetermined time.

13. Starting means for a gasturbine which includes an electric ignition circuit, said starting means comprising an electric motor adapted to 'be connected to the gas turbine for starting it,

a contactor for connecting said motor to a source of electric energy, manual means for efiecting operation of said contactor to closed position, means responsive to the motor current for maintaining the contactor in closed position, said current-responsive means being adapted to cause operation of the contactor to open position to deenergize the motor when the motor current decreases below a predetermined value, means associated with the contactor for eiiecting energization of said ignition circuit substantially simultaneously with energization of the motor, and timing means for effecting deenergization of the motor and of the ignition circuit at the end of a predetermined time.

14. Starting means for a gas turbine which includes an electric ignition circuit, said starting means comprising an electric motor adapted to .be connected to the gas turbine for starting it, a

predetermined value, means associated with the contactor for efiecting energization of said ignition circuit substantially simultaneously with energization of the motor, and a timing motor energized simultaneously with the ignition circuit. said timing motor being adapted to efiect deen 8 ergization of the motor and of the ignition circuit at the end of a, predetermined time.

15. Starting means for a gas turbine which includes an electric ignition circuit, said starting means comprising an electric motor adapted to be connected to the gas turbine for starting it, a contactor for connecting said motor to a source of electric energy, a control circuit, manual means for energizing said contactor from said controlcircuit to cause operation of the contactor to closed position, means responsive to the motor current for maintaining energization of the contactor to hold it in closed position, said current-responsive means being adapted to cause operation of the contactor to open position to deenergize the motor when the motor current decreases below a predetermined value, means associated with the contactor for eiiecting connection of said ignition circuit to the control circuit to be energized thereby substantially simultaneously with energization of the motor, contact means for maintaining energization of the ignition circuit independently of the contactor, and timing means adapted to efiect interruption of the control circuit at the end of a predetermined time.

16. Starting means for a, gas turbine which includes an electric ignition circuit, said starting means comprising an electric motor adapted to be connected to the gas turbine for starting it, a contactor for connecting said motor to a source of electric energy, a control circuit including a normally closed contact, manual means for energizing said contactor from said control circuit to cause operation of the contactor to closed position, means responsive to the motor current for maintaining energization of the contactor to hold it in closed position, said current-responsive means being adapted to cause operation of the contactor to open position to deenergize the motor when the motor current decreases below a predetermined value, means associated with the contactor for effecting connection of said ignition circuit to the control circuit to be energized thereby substantially simultaneously with energization of the motor, contact means for maintaining energization of the ignition circuit independently of the contactor, and a timing motor, said timing motor being connected so as to be energized from the control circuit, the timing motor being adapted to effect opening of said normally closed contact in the control circuit at the end of a predetermined time. I

BAS-CUM O. AUSTIN. OMAR C. WALLEY.

REFERENCES CITED The following references are of record in the file of this patent:

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