GB2178844A

GB2178844A - A fuel control system for a gas turbine engine

Info

Publication number: GB2178844A
Application number: GB08617067A
Authority: GB
Inventors: Robert Noel Penny; Peter Malcolm Rackham
Original assignee: Noel Penny Turbines Ltd
Current assignee: Noel Penny Turbines Ltd
Priority date: 1985-07-13
Filing date: 1986-07-14
Publication date: 1987-02-18
Also published as: GB8617067D0

Abstract

An electro-optical sensor for controlling the speed of a fuel pump of a gas turbine engine. The sensor 2 includes a detector which receives intermittent pulses of light from a light source. The light source and detector are aligned at 7 on either side of a disc 5 mounted for rotation on a turbine-driven alternator shaft 4 providing power for driving the fuel pump. The disc 5 has circumferentially-spaced peripheral slots or notches 6 therein which produce pulses of light as the discs rotates. The sensor 2 produces signals corresponding to the pulses and these are fed to an electronic processor controlling the fuel pump. The detecter and source may be, respectively, a card-mounted silicon light sensor and a spectrally-matched gallium arsenide source. <IMAGE>

Description

SPECIFICATION Afuel control system for a gas turbine engine The invention relates to a fuel control system for a gas turbine engine.

According to the invention, the fuel control system includes a sensor responsive to an electromagneticradiationfrom a directional source thereof; means mounted on a shaftofthe gas turbine engine for rotation thereby and positioned between the source and a detector ofthe sensorto produce intermittent pulses of said electromagnetic radiation impinging on the detector at a rate in direct proportion to the speed of rotation of the shaft, the sensor providing corresponding output signals to a control means in the fuel control system.

The electromagnetic radiation source may be a lightsource,the sensor in thatcase being of an electro-optical kind.

The means for producing the intermittent pulses of rotation may be a radiation-opaque disc mounted on the shaft for rotation therewith and hav ing therein at least one aperture or radiationtransparent region through which the radiation will pass from the source to the detector of the sensor. For example, where the radiation is light, the disc may have an aperture or peripheral slot or notch or a plurality of circumferentially-spaced apertures or peripheral slots or notches therein through which the light will pass to a detectorofthe sensor.

The shaft on which the disc or pulse-producing means is mounted may be the main turbine shaft shaft or an ancillary shaft coupled to the main turbine shaft. Theshaft may bea drive shaft for an alternatorto provide power for a varia bl e speed elec- trically-operablefuel pump.

The control means receiving signalsfrom the sen sor may include an electronic processorfor controlling a variable speed electrical fuel pump of thefuel control system, By way of example, an electro-optical sensor arrangement in accordance with the invention is now described with reference to the accompanying drawings, in which; Figure lis a front end view of a nose bulletin a gas turbine engine and incorporating the sensor, and Figure2is an axial section ofthe nose bullet shown in Figure 1.

Referring to the drawing, the nose bullet housing is shown at 1 and the electro optical sensor 2 is mounted on a mounting 3fixed to the housing or otherfixed partthereof.Theshaftofwhichthe speed is to be detected is shown at 4. In this case the shaft is a turbine-driven shaft of an alternator to be used to provide power for an electrically oper ablefuel pump. The shaft 4 has a discS keyed to it for rotation therewith. The disc5 has a plurality of peripheral slots or notches 6 circumferentially spaced around it at equal intervals.The sensor 2 is responsive to intermittent pulses of light reaching a detectorfrom a light source aligned in a direction parallel to the axis of rotation of the disc switch the cross indicated at7 in Figure 1.The light source and detector are positioned one at each side ofthe dise and are indicated by reference 8 in Figure 2. As the shaft 4and thusthe discS rotate, the sensor2 will be intermittently energised in pulses as each notch 6 becomes aligned with the light source and detector 8. The sensor 2 produces signals corresponding to the pulses and these are fed to an electronic processorcontrolling the speed of the fuel pump. Thus the sensor2 is a pick-up and the discS is an encoder.

During engine start-upthefuel flow is governed automatically, according to a pre-set schedule utilising a speed/time curve. The electro-optical speed sensor 2 provides feedback information for the controlling processor and maintains the turbine on a pre-setstartcurve.

Once the engine is running the turbine speed would be set manually (as in a vehicle application) or automatically (as with some electrical generating sets). Du ring th is ti me the electro-optical sensor 2 provides feedback information to the pro cessorandthus maintains the turbine speed.

Also the electro-optical sensor 2 may provide speed signal informati nto prevent turbine over speed, via a pre-set upper limit programmed into the processor.

The sensor 2 may be a commerically-available, card-mounted silicon light sensor and may be responsive to a spectrally-matched gallium arsenide light source.

As aforesaid the slotted disc 5 may alternatively be mounted on thefuel pump driving shaftor on an ancillary shaft coupled to the main turbine shaft.

The number oftimes the circuit of the sensor 2 is made and broken per rotation ofthe shaft depends on the number of notches orslots 6. This may be varied to suit turbine speed to provide the best signal definition to the processor. More notches orslots 6 would be required for use in a larger.engine running sloweFthan irka smal-ler engine-.

running faster in orderto providethesame quality of signal.

Figure 1 also shows a second optical sensor 2' and its associated light source indicated at 7' for use as a back-up for test purposes.

1. Afuel control system for a gas turbine engine including a sensor responsive to an electromagnetic radiation from a directional source thereof; means mounted on a shaft ofthe gas turbine engine for rotation thereby and positioned between the source and a detector of the sensorto produce intermittent pulses of said electromagnetic radiation impinging on the detector at a rate in direct proportion to the speed of rotation of the shaft, the sensor providing corresponding outputsignalsto a control means in the fuel control system.

2. Afuel control system as claimed in Claim 1 in which the electromagnetic radiation source is

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Afuel control system for a gas turbine engine The invention relates to a fuel control system for a gas turbine engine. According to the invention, the fuel control system includes a sensor responsive to an electromagneticradiationfrom a directional source thereof; means mounted on a shaftofthe gas turbine engine for rotation thereby and positioned between the source and a detector ofthe sensorto produce intermittent pulses of said electromagnetic radiation impinging on the detector at a rate in direct proportion to the speed of rotation of the shaft, the sensor providing corresponding output signals to a control means in the fuel control system. The electromagnetic radiation source may be a lightsource,the sensor in thatcase being of an electro-optical kind. The means for producing the intermittent pulses of rotation may be a radiation-opaque disc mounted on the shaft for rotation therewith and hav ing therein at least one aperture or radiationtransparent region through which the radiation will pass from the source to the detector of the sensor. For example, where the radiation is light, the disc may have an aperture or peripheral slot or notch or a plurality of circumferentially-spaced apertures or peripheral slots or notches therein through which the light will pass to a detectorofthe sensor. The shaft on which the disc or pulse-producing means is mounted may be the main turbine shaft shaft or an ancillary shaft coupled to the main turbine shaft. Theshaft may bea drive shaft for an alternatorto provide power for a varia bl e speed elec- trically-operablefuel pump. The control means receiving signalsfrom the sen sor may include an electronic processorfor controlling a variable speed electrical fuel pump of thefuel control system, By way of example, an electro-optical sensor arrangement in accordance with the invention is now described with reference to the accompanying drawings, in which; Figure lis a front end view of a nose bulletin a gas turbine engine and incorporating the sensor, and Figure2is an axial section ofthe nose bullet shown in Figure 1. Referring to the drawing, the nose bullet housing is shown at 1 and the electro optical sensor 2 is mounted on a mounting 3fixed to the housing or otherfixed partthereof.Theshaftofwhichthe speed is to be detected is shown at 4. In this case the shaft is a turbine-driven shaft of an alternator to be used to provide power for an electrically oper ablefuel pump. The shaft 4 has a discS keyed to it for rotation therewith. The disc5 has a plurality of peripheral slots or notches 6 circumferentially spaced around it at equal intervals.The sensor 2 is responsive to intermittent pulses of light reaching a detectorfrom a light source aligned in a direction parallel to the axis of rotation of the disc switch the cross indicated at7 in Figure 1.The light source and detector are positioned one at each side ofthe dise and are indicated by reference 8 in Figure 2. As the shaft 4and thusthe discS rotate, the sensor2 will be intermittently energised in pulses as each notch 6 becomes aligned with the light source and detector 8. The sensor 2 produces signals corresponding to the pulses and these are fed to an electronic processorcontrolling the speed of the fuel pump. Thus the sensor2 is a pick-up and the discS is an encoder. During engine start-upthefuel flow is governed automatically, according to a pre-set schedule utilising a speed/time curve. The electro-optical speed sensor 2 provides feedback information for the controlling processor and maintains the turbine on a pre-setstartcurve. Once the engine is running the turbine speed would be set manually (as in a vehicle application) or automatically (as with some electrical generating sets). Du ring th is ti me the electro-optical sensor 2 provides feedback information to the pro cessorandthus maintains the turbine speed. Also the electro-optical sensor 2 may provide speed signal informati nto prevent turbine over speed, via a pre-set upper limit programmed into the processor. The sensor 2 may be a commerically-available, card-mounted silicon light sensor and may be responsive to a spectrally-matched gallium arsenide light source. As aforesaid the slotted disc 5 may alternatively be mounted on thefuel pump driving shaftor on an ancillary shaft coupled to the main turbine shaft. The number oftimes the circuit of the sensor 2 is made and broken per rotation ofthe shaft depends on the number of notches orslots 6. This may be varied to suit turbine speed to provide the best signal definition to the processor. More notches orslots 6 would be required for use in a larger.engine running sloweFthan irka smal-ler engine-. running faster in orderto providethesame quality of signal. Figure 1 also shows a second optical sensor 2' and its associated light source indicated at 7' for use as a back-up for test purposes. CLAIMS

2. Afuel control system as claimed in Claim 1 in which the electromagnetic radiation source is a light source and the sensor is of the electro-optical kind.

3. Afuel control system as claimed in Claim 1 or2 in which the means for producing the intermittent pulses of radiation is a radiation-opaque disc mounted on the shaftforrotationthere- with and having therein at least one aperture or radiation-transparent region through which the radiation will pass from the source to the detector of the sensor.

4. Afuel control system as claimed in Claim 3 in which, where the disc is required to interrupt a light source, the disc has an aperture or peripheral slot or notch or a plurality of circumferentiallyspaced apertures or peripheral slots or notches there in through whichthe lightwill pass to a detector of the sensor.

5. Afuel control system as claimed in any precedins claim in which the shaft on which the pulse-producing means is mounted is the mainturbine shaft.

6. Afuel control system as claimed in any one of Claims 1-4 in which the shaft on which the pulse-producing means is mounted is an ancillary shaftcoupled to the main turbine shaft.

7. Afuel control system as claimed in any one of Claims 1-4 in which the shaft on which the pulse-producing means is mounted is a drive shaftfor an alternatorto provide powerforavariable speed electrically-operable fuel pump.

8. Afuel control system as claimed in any preceding claim in which the sensor comprises an electronic processorfor controlling a variable speed fuel pump ofthefuel control system.

9. An electro-optical sensor arrangement for a fuel system of a gas turbine engine substantially as described herein and shown in the accompanying drawings.