Deceleration detector

Abstract

A regenerative gas turbine engine has a burner apparatus with a combustion zone and a dilution zone therein and valve means for controlling the amount of air flow into the combustion zone under the control of a deceleration detector including a pressure sealed housing with a movable diaphragm therein forming first and second pressurizable chambers one of which senses discharge pressure of a compressor driven by gas turbine means responsive to vehicle deceleration produced by reduced fuel flow to the burner apparatus. Orifice means in the diaphragm controls pressurization of the chambers by the compressor and spring means are operative to maintain contacts closed during steady state and increasing compressor discharge pressure modes of operation so as to condition the valve means for increased air flow to the combustion zone and the orifice means serve to produce an imbalance of pressure across the diaphragm under vehicle deceleration conditions so as to open the contacts and thereby condition the valve means to reduce air flow to the combustion zone.

Description

This invention relates to regenerative gas turbine engines and more particularly to improved means for controlling burner apparatus therein in response to vehicle deceleration.

In control of regenerative gas turbine engines, variable geometry burners are employed to reduce exhaust emissions. One approach has been to include a movable valve element to control the flow of primary air into a combustion zone of the burner. The gas compressor for the regenerative engine decelerates under certain conditions and in this case it has been found desirable to position the valve element into a closed position to minimize air flow into the burner combustion zone under vehicle deceleration conditions and to position the valve open during vehicle acceleration to produce more air flow as more fuel is directed to the burner. Various fuel controllers have been proposed to regulate air/fuel ratio to the burner of a gas turbine engine. Such controllers have utilized various engine operating parameters such as sensing the temperature of exhaust gases from the burner apparatus and/or compressor discharge pressure so as to maintain a desired control of the ratio of air/fuel flow to the burner apparatus.

An object of the present invention is to provide a simplified control apparatus for maintaining a controlled air/fuel ratio to the burner apparatus of a gas turbine engine by the provision of a decelerator detector including means for detecting steady state and increasing compressor discharge pressure as a basis of operation and valve means responsive thereto to increase the flow of air from a compressor into the burner apparatus combustion zone to maintain a predetermined air/fuel ratio therein and further including means responsive to a decrease in compressor discharge pressure reflecting a decrease in fuel flow to the burner apparatus combustion zone as occurs at vehicle deceleration to control the valve means to reduce the amount of air flow into the combustion zone so as to maintain the desired air/fuel ratio under vehicle deceleration conditions.

Still another object of the present invention is to provide an improved air/fuel ratio controller in a gas turbine engine operative in response to compressor discharge pressure to vary the amount of air flow into the combustion zone of burner apparatus so as to maintain a desired air/fuel ratio thereto by the provision of a detector having a gas tight body that houses a diaphragm to define first and second pressure chambers one of which is in direct communication with compressor discharge pressure and the other of which is maintained under a balanced pressure by flow across orifice means and wherein a pair of contacts are operated by the diaphragm and maintained normally closed by spring means during steady state, balanced pressure conditions to complete an energization circuit to means for controlling a valve that will maintain increased air flow to the combustion zone during vehicle operations wherein the compressor is operated to produce a steady state discharge pressure or an increasing discharge pressure and wherein the orifice means responds to a decreasing compressor discharge pressure to produce a pressure imbalance across the diaphragm to condition the contacts open thereby to cause the valve means to reduce the amount of air flow to the combustion zone under vehicle deceleration operation thereby to maintain a desired air/fuel ratio in the combustion zone.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

FIG. 1 is a diagrammatic view of a regenerative gas type turbine engine including the present invention;

FIG. 2 is an enlarged, fragmentary cross sectional view taken along the line 2--2 of FIG. 1, and

FIG. 3 is an enlarged cross sectional view of a deceleration detector used in the present invention.

Referring now to the drawings, in FIG. 1 a regenerative type gas turbine engine 10 as illustrated including a compressor 12 having an inlet 14 and an outlet connected to a discharge conduit 16 connected to one end of a first heat exchange pass 18 in a regenerator 20. The regenerator pass 18 is connected by an air supply conduit 21 to an outer case 22 for a combustion or burner apparatus 24. The burner apparatus 24 includes an inner liner 26 that has a combustion zone 28 therein in communication with a plenum 30 defined by the outer case 22 around the liner 24 across a plurality of primary air ports 31, 32 therein for supplying primary combustion air to the combustion zone 28. A fuel supply for the apparatus 24 is defined by a fuel line 34 connected across a fuel control valve 36 to a fuel supply nozzle 38 for directing fuel into the combustion zone 28 under the control of an accelerator throttle 40 coupled to valve 36. The throttle 40 controls the valve 36 to direct fuel into the combustion zone 28 to provide an air/fuel ratio in the combustion zone 28 for maintaining a temperature of combustion to retard the formation of nitrogen oxides by combination of nitrogen and oxygen present in the air supply to the engine. Burner apparatus 24 further includes a plurality of secondary or dilution air ports 42 therein that supply air into a dilution zone within the liner 26 downstream of the combustion zone 28. A burner exhaust 44 directs combustion products across a gasifier turbine 46 connected to a shaft 48 that is coupled to the compressor 12 for driving it during burner operation. Exhaust from the gasifier turbine 46 is directed through a power turbine 50 thence through an exhaust conduit 52 across a second heat exchanger pass 53 of the regenerator 20 thence through an exhaust conduit 54 to atmosphere.

The power turbine 50 has an output shaft 56 that is coupled to a power train for a vehicle.

Referring now to FIG. 2, the air flow to the combustion zone 28 is under the control of an annular valve sleeve 58 that includes a plurality of ports 60 at circumferentially spaced points therearound that are located in overlying relationship to the primary air flow ports 32 to control the proportion of air flow through the primary air ports 32 and dilution ports 42 from the plenum 30. The sleeve 58 as illustrated in FIG. 2 is in a closed position wherein the primary air ports 32 are blocked by a plurality of intermediate land portions 62 on the sleeve valve 58 between each of the ports 60 therein. A radially outwardly directed lug 64 on the sleeve 58 is pivotally connected to one end of a link 66 that has its opposite end pivotally connected to an output shaft 68 of a fluid motor 70 including a cylinder 72 having a piston 74 slidably supported therein for opposite reciprocation between the closed position shown in solid line in FIG. 2 and an open position shown in dotted line in FIG. 2. The piston 74 is connected to shaft 68 and divides the cylinder 72 into chambers 76, 78 communicated respectively by fluid lines 80, 82 that are connected to a three-way solenoid valve 84. When the sleeve 58 is in a closed position, the valve 84 is positioned to communicate a pressurized source of air 86 through the pressure conduit 82 into the chamber 78 to force the piston 74 to the left as shown in solid line in FIG. 2. Chamber 76 is then in communication with an exhaust port 88 of the valve 84. Conversely, when the fluid motor 70 is conditioned to open the sleeve 58 the valve 84 will direct pressurized air from the source 86 through the conduit 80 into the chamber 76 and the chamber 78 will be exhausted through the port 88 to move the piston 74 to the right as shown in dotted line in FIG. 2. This will rotate sleeve valve 58 to communicate ports 32, 60.

In the illustrated arrangement the solenoid valve 84 is under the control of a deceleration detector 90 including a pressure sealed housing made up of a first cover 92 of cup-shaped configuration including a peripheral flange bent over at 94 into pressure sealed relationship with a radially outwardly directed flange 96 on a housing member 98. Housing member 98 includes a signal port 100 thereon that is communicated through a signal line 101 to sense compressor discharge pressure in the conduit 16. The housing has a movable flexible diaphragm 102 therein with its peripheral edge press fit in sealing relationship between the flange 96 and the flange 94. The diaphragm 102 separates the housing into first and second pressure chambers 104, 106. A bleed orifice 108 is formed in the diaphragm 102 to equalize the pressure between the chambers 104, 106.

The housing member 92 has an electrical contact 110 supported thereon connected to a terminal 112 that is electrically connected by a wire 114 to the solenoid 116 of the valve 84. The terminal 112 is electrically insulated from the body 92. A second contact 115 is secured to the diaphragm 102 by suitable means representatively shown as a rivet 116 so as to be moved with respect to the contact 110 between open and closed positions therewith. The contact 115 is connected by means of a wire 118 to a second terminal 120 secured to the body 92 and electrically insulated therefrom. Terminal 120 is electrically connected by means of a wire 122 to a suitable source of power for the control circuit. The deceleration detector 90 further includes a coil spring 124 having one end thereof in engagement with the diaphragm 102 and the other end thereof in engagement with the housing portion 98 so as to bias the diaphragm 102 to maintain the contacts 110, 115 normally closed when pressure is balanced between chambers 104, 106.

In operation the system responds to steady state vehicle operation and vehicle operation that produces an increasing compressor discharge pressure at the signal conduit 101 to produce a pressure within the chambers 104, 106 that is equalized across the orifice 108. During these modes of operation the spring 124 will maintain the contacts 110, 115 closed. This will condition the solenoid 116 to maintain the valve 84 to position piston 74 as shown in dotted line in FIG. 2 so as to shift the sleeve 58 into a position to cause the openings 60 therein to overlie the primary air ports 32 thus to maintain an increased level of air flow into the combustion chamber 28 which corresponds to an increased fuel flow thereto across the valve 36 in accordance with the position of throttle 40.

Under conditions where the vehicle is decelerated by movement of the throttle 40 to reduce fuel flow to the combustion chamber 28, reduced air flow to the combustion chamber 28 is required to maintain a desired air fuel ratio to the combustor or burner apparatus 24. Under vehicle deceleration the gas turbine shaft 48 will drive the compressor 12 at a reduced speed and will thereby produce a mode of operation wherein the compressor discharge pressure decreases. Assuming an initial steady state condition wherein the pressure is balanced across the chambers 104, 106 the chamber 106 pressure will be reduced relative to the pressure in chamber 104 in response to the decreased compressor discharge pressure. Moreover, the orifice 108 is sized to be sufficiently small so that the pressure in the chamber 104 will be maintained greater than that in the chamber 106 for a predetermined delay. This will produce an unbalanced force on the diaphragm 102 acting to the right as illustrated in FIG. 3, to overcome the spring force to cause it to compress thereby resulting in the contacts 110, 114 being opened. At this point the energization of the solenoid 116 will condition the valve 84 to position the piston 74 in the solid line position shown in FIG. 2 resulting in arcuate movement of the sleeve 58 to the illustrated position in FIG. 2 to reduce the amount of air flow into the combustion chamber 28 thereby to maintain a desired air/fuel ratio therein to control the formation of nitrogen oxides in the burner assembly 24.

The rate of compressor discharge pressure decrease which is necessary to open the contacts 110, 115 and the duration of time during which the contacts will remain open due to the imbalance of pressure across the diaphragm 102 depends upon the volume of the chambers 104, 106 along with the preload of the spring 124, its rate and the size of the orifice 108. The reduction of air flow into the combustion zone 28 during deceleration gives good burner control during vehicle deceleration. The system is eadily adjustable by use of a fine needle valve in place of the orifice 108 and an adjustable spring for positioning the fine needle valve. Such an arrangement permits tailoring of the device for optimum performance. Another advantage of the arrangement is that the deceleration detector can also be utilized as a means to detect gasifier decelerations under engine test conditions and thus has a use for purposes other than burner control of the type illustrated in FIG. 1.

While the embodiments of the present invention, as herein disclosed, constitute a preferred form, it is to be understood that other forms might be adopted.

Claims

What is claimed is:

1. A deceleration control system for a gas turbine engine comprising: burner apparatus having an outer case for receiving combustion air, compressor means for supplying air to said outer case, a burner liner located within said outer case including a combustion zone and a dilution zone, throttle means for directing fuel into said combustion zone, a first plurality of primary air ports in said liner for directing air from the outer case into the primary zone, a second plurality of ports in said liner for directing air from the outer case into said dilution zone, valve means operable to control the ratio of air directed into the combustion zone and dilution zone, turbine means energized by the burner apparatus connected to drive said compressor means and a vehicle power shaft, a decelerator sensor including a pressure sealed housing having a flexible diaphragm forming first and second pressurizable chambers within said housing, a signal port in said housing for directing discharge pressure from said compressor means into one of said chambers, orifice means located between said first and second chambers to maintain a balanced pressure thereacross under steady state engine operation, switch means operated by said diaphragm between open and closed position, spring means for biasing said diaphragm to close said switch means during steady state compressor discharge pressure operation, means responsive to closure of said switch means to condition said valve means to direct a predetermined amount of compressed air through the primary air ports in said liner to the combustion zone during steady state and increasing compressor discharge pressure operation, said first pressurizable chamber having the pressure therein reduced during engine deceleration and said orifice means being selected to retain pressure in said second chamber to produce an unbalanced force across said diaphragm in opposition to said spring means to produce opening of said switch means, said valve means being responsive to opening of said switch means to reduce flow of primary air into said combustion zone to reduce the power supply to said turbine means under vehicle deceleration conditions.

2. A turbine engine control system for regulating the output temperature of a burner assembly in accordance with vehicle operation comprising: compressor means having an inlet and an outlet, turbine means including a power output shaft and means connected to said compressor means to drive said compressor means in accordance with vehicle acceleration and deceleration, a burner apparatus including an outer case for receiving compressed air from said compressor means, a burner liner within said outer case including primary and secondary air ports therein, a combustion zone within said liner in communication with said primary ports and a dilution zone within said liner in communication with said secondary air ports, throttle means for supplying fuel to said combustion zone, valve means for varying the proportion of air flow from the outer case through said primary and secondary air ports to regulate the air flow into said combustion zone to control the output temperature of said burner apparatus, a servo switch including a pressure tight housing having a movable diaphragm therein separating said housing into first and second pressurizable chambers, a signal port in said housing for communicating said first chamber with the compressor discharge pressure, orifice means for communicating said first and second chambers to balance pressure therein in accordance with compressor discharge pressure under steady state and increasing compressor discharge pressure operating conditions, switch means operated by said diaphragm between open and closed positions, spring means for biasing said diaphragm when pressure is balanced between said first and second chambers to maintain said switch means closed, control means responsive to closure of said switch means to condition said valve means to direct an increased quantity of air into said combustion zone, said orifice means being sized to maintain an imbalanced pressure between said first and second chamber when the compressor discharge pressure is reduced upon vehicle deceleration to cause said diaphragm to move in opposition to said spring means to condition said switch means open, said control means being responsive to opening of said switch means to condition said valve means to reduce the amount of air flow into said combustion zone thereby to produce a reduced burner temperature outlet for reducing output power from said turbine means under vehicle deceleration conditions of operation.

3. A regenerative gas turbine comprising: in combination, air compressor means, combustion apparatus supplied from said compressor means said combustion apparatus including a combustion products generator including a combustion zone and a dilution zone, turbine means energized from the combustion apparatus connected to drive said compressor means, a heat exchanger and a turbine exhaust duct connected through one pass of the heat exchanger, said heat exchanger having a second pass in heat exchange relation to the first pass, a compressed air conduit leading from the compressor to said second pass for directing air to the combustion apparatus, said combustion apparatus including a liner having primary and secondary air ports therein leading to said combustion zone and dilution zone respectively, valve means for controlling the ratio of air flow from the compressor into said combustion and dilution zones for controlling the outlet temperature of said burner apparatus, means for directing fuel to said combustion zone including a throttle, said combustion apparatus being responsive to a reduced flow of fuel upon vehicle deceleration to produce a reduced temperature in said combustion apparatus with a resultant decrease in output power from said turbine means, a deceleration detector including a sealed housing having a signal port thereto for sensing the discharge pressure of said compressor means, a movable diaphragm within said sealed housing separating it into first and second pressurizable chambers, orifice means for communicating said first and second chambers to balance pressures therebetween under steady state and increasing compressor discharge pressure operation, switch means operated by said diaphragm between open and closed positions, spring means for biasing said diaphragm to hold said switch means closed when pressures are equalized in said first and second chambers during steady state and increasing modes of compressor discharge pressure operation, means responsive to closure of said contacts to condition said valve means to increase flow of air to said combustion zone, said orifice means being operative during a decreasing compressor discharge pressure produced by a deceleration mode of throttle operation to maintain a greater pressure within one of said chambers to bias said diaphragm against said spring means to open said switch means, said control means being responsive to opening of said switch means to condition said valve means to reduce the amount of air flow to the combustion zone.