Quick release turbine gate valve

A gas turbine engine has a compressor and power turbine driven by gas flow across a nozzle arrangement that includes a partial admission gate valve therein movable into and out of overlying relationship with a limited number of vanes of the nozzle in order to control power output therefrom during part load operation of the engine. The gates are operated by quick response pneumatic operators having a regulated source of pressure applied to the operators to close the gates during a low power, road load mode of engine operation; an orifice restricts flow into a pressurizable chamber formed in part by a movable power diaphragm to cause a controlled buildup of pressure therein and a slow velocity extension of the operator to position the gates in part power position and wherein means are included to produce a slow rate retraction to avoid excess turbine temperatures and wherein dump means disconnect the regulated pressure from the operator whereby the diaphragm is snapped by a return spring to produce a quick spring biased opening of the gate valve from its partial blocking position to a full open position during a time period that prevents turbine compressor surge as the gas turbine engine responds to a higher power demand wherein greater gas flows through the nozzle for increasing power output from the power turbine of the engine.

This invention relates to gas turbine engine control systems and more 
particularly to gas turbine engine control systems utilizing gates for 
regulating gas flow through a power turbine nozzle to regulate the power 
turbine output from a gas turbine engine. 
Various proposals have been suggested for controlling the amount of motive 
fluid directed across the nozzle of a power turbine of a gas turbine 
engine. One such arrangement is shown in U.S. Pat. No. 3,025,668 issued 
Mar. 20, 1962, to Mock. The system includes an adjustable damper plate 
that is arranged in overlying relationship to a diaphragm guide member and 
rotated with respect to spaced, arcuate sets of turbine nozzle vanes 
therein for controlling the amount of motive fluid directed into the 
turbine wheel for controlling the amount of power output therefrom. 
U.S. Pat. No. 2,565,178 issued Aug. 21, 1951, to Imbert, discloses another 
suggestion for blocking part of the gas flow through the turbine nozzle of 
a gas turbine engine. In this arrangement, a cylinder is moved selectively 
into and out of the flow passages between the vanes of the turbine 
expansion nozzle leading to the turbine wheel of the gas turbine engine. 
The movable flow regulating components of the aforesaid patents are 
connected to linkages which require a substantial time period for 
actuation. 
In present day automotive gas turbine type engines, lightweight gate valve 
components of low inertia are incorporated in association with specially 
formed turbine nozzle arrangements to effect a controlled, regulation of 
gas flow through the power turbine to tailor the output power from the 
engine in a manner to improve specific fuel consumption under part load 
conditions of operation. Such control devices are set forth in co-pending 
U.S. Ser. No. 50,411 to Albert H. Bell III, filed June 20, 1979, with a 
common assignee to the present invention. In such arrangements, it is 
desirable to utilize a pneumatic operator for positioning the gate valves; 
the operator including modes of operation to control the gate movement for 
a slow insertion and retraction of the gate between closed and open 
positions thereof and a quick retraction of the gate from its blocking 
position under a condition of engine operation which might otherwise cause 
engine surge. 
Further, under normal road load conditions of gas turbine engine operation, 
the power capacity of the engine exceeds that required for operating road 
vehicles. Accordingly, various proposals have been suggested to reduce the 
fuel requirements for a gas turbine engine under part load conditions. One 
approach has been to utilize a split compressor of the type set forth in 
U.S. Pat. No. 3,625,003, issued Dec. 7, 1971, to Liddle. In this 
arrangement, under part load conditions, only a part of the gas capacity 
is utilized thereby to better match the engine characteristics to load 
requirements under part load conditions. Another approach to improved part 
load operation is set forth in co-pending United States application, Ser. 
No. 792,814, filed Oct. 15, 1976, to Liddle et al for a variable flow 
capacity gas turbine engine for improved part load fuel economy. In this 
arrangement a proposal is made to selectively control the amount of gas 
flow through a gas turbine engine in accordance with its power and road 
load requirements, thereby to improve specific fuel consumption 
characteristics of the engine. 
In high performance, light weight gas turbine engines, it is desirable to 
have quick response control characteristics and as a result a part load 
controller with quickly operable components is proposed in the aforesaid 
co-pending application, Ser. No. 50,411 filed June 20, 1979, of Albert H. 
Bell III for use with a 360.degree. nozzle ring of a power turbine of an 
automotive gas turbine engine wherein the gates are selectively positioned 
at upstream edges of a limited number of the nozzle vanes and selectively 
moved in a plane arranged perpendicularly to that of the axis of rotation 
of the power turbine from a stored position out of the hot gas flow path 
through the turbine and in a way to prevent excessive gas leakage from the 
gas flow path and movable into the gas flow path to assume a blocking 
position with respect to the leading edge where a portion of the gate 
valve is pressure biased against flat portions of the leading edge of a 
limited number of the nozzle vanes to block flow therethrough them in a 
controlled fashion to increase the turbine inlet temperature for improved 
thermodynamic operation of the engine. 
Accordingly, an object of the present invention is to provide an improved 
pneumatic control system for regulating controlled response movement of 
gate valves between blocking and open positions in a turbine nozzle 
arrangement; the control system including means to produce a controlled 
rate insertion and retraction of the gate valves between blocking and open 
positions with respect to the nozzle vanes between idle speed and road 
speed conditions of operation of a gasifier of the engine thereby to 
prevent sudden changes in the output power of the engine and wherein the 
control system has an improved pneumatic operator selectably connected to 
atmosphere to condition the controller for a quick dump retraction of the 
gates from their blocking position to a storage position wherein the gas 
flow path through the turbine nozzle is completely opened to accommodate 
increased mass flow of combustion products to the turbine nozzle in 
response to operation of an acceleration command thereby to prevent engine 
surge during such acceleration modes of operation. 
Still another object of the present invention is to improve pneumatic 
control systems for use with dual gate valve components of low inertia for 
closely regulating flow through a limited number of passages in a full 
360.degree. ring of nozzle vanes upstream of a power turbine of an 
automotive type gas turbine engine wherein the system includes a pneumatic 
operator connected to a regulated source of pressure through a solenoid 
valve responsive to control signals including but not limited to the 
turbine speed and wherein an inlet control to the pneumatic operator has a 
supply orifice selected to direct the regulated pressure into a 
pressurizable chamber formed in part by a power diaphragm responsive to a 
slow rate of pressure build-up as established by the supply orifice to 
slowly extend the operators to produce a first slow rate blockage of the 
passages through the nozzle to produce an increase in the turbine inlet 
temperature thereby to produce a greater thermal efficiency of engine 
operation under road load conditions of engine operation; and wherein the 
pressurizable chamber is selectively communicated with a second orifice 
controlled bleed path to atmosphere under conditions of operation to 
prevent excessive increases in regenerator temperature during operation of 
the engine under road load conditions so that bleed through the second 
orifice is at a slow controlled rate to cause a selective slow rate 
retraction of the control gates from blocking positions in the nozzle 
thereby to produce a gradual power change regulated by the restricted air 
flow; the improved control system including dump means being responsive to 
a dump control signal for producing a rapid depressurization of the 
pressurizable power chamber to cause a quick shift of the power diaphragm 
for an immediate removal of the gate valves from the nozzle thereby to 
prevent engine surge during a demand acceleration phase of engine 
operation. 
Yet another object of the present invention is to improve pneumatic control 
systems for turbine engine gate valves as set forth in the preceding 
object wherein the dump control means includes a solenoid controlled 
flapper selectively positioned against a valve seat on the end of a low 
volume dump tube attached directly to the housing of the pneumatic 
operator.

Referring now to the drawings, in FIG. 1, an automotive gas turbine engine 
10 is illustrated having a gas coupled gasifier spool 12 and power turbine 
spool 14. The gasifier spool 12 includes a compressor 16 that is connected 
to a high pressure gasifier turbine wheel 18 by a drive shaft 20 so that 
the compressor 16 is driven to take in atmospheric air, compress it and 
supply it to a combustor 22 through an inlet air pass 24 of a heat 
exchanger 26 that further includes an exhaust heat pass 28 therethrough 
for extracting heat from engine exhaust for preheating of the compressed 
inlet air directed through the air pass 24 of heat exchanger 26. Fuel is 
supplied to the combustor 22 from a suitable source such as an engine 
driven pump (not illustrated) through a fuel controlling or fuel metering 
valve 30 and an engine fuel supply line 32. Combustion products resulting 
from burning of the fuel and the air within the combustor 22 are directed 
through an outlet transition 34 from the combustor 22 thence through an 
annular row of nozzle vanes 36 against turbine blades 38 on a rotor rim 40 
of the high pressure turbine wheel 18 to extract energy for rotation of 
the compressor 16. The motive fluid from the outlet transition 34 of the 
combustor 22 is further directed through a gas flow path 42 formed by an 
annular internal shroud 44 of the engine and an internally located wall 
46. The flow path 42 communicates with a power turbine nozzle 48 having an 
annular row of turbine vanes 50 therein between the inner surface 52 of 
the shroud 44 and an inner annular band 54 of the power turbine nozzle 48 
as best seen in FIG. 2. The turbine vanes 50 each include a leading edge 
56 and a trailing edge 58 as well as a suction surface 60 and a pressure 
surface 62 for directing motive fluid against turbine blades 64 on a rotor 
wheel 66 of the power turbine spool 14 to extract power from motive fluid 
directed thereagainst from the power turbine nozzle 48 and thereby to 
transfer power to an output shaft 68 connected to a suitable transmission 
70 and road drive wheels 72. Details of the transmission and drive wheels 
are omitted herewith for purposes of clarification; however, such details 
are well known devices used in conjunction with automotive type gas 
turbine engines. For example, the transmission 70 typically includes some 
form of clutch or other device which allows the output shaft 68 to rotate 
when the drive wheels 72 are stationary. Examples of such arrangements are 
releasable clutch, slipping clutch, a fluid flywheel or most likely a 
torque converter since such converters produce best operating 
characteristics in such vehicles. The transmission 70 may also, as is 
usual, include forward drive gears of several ratios and a reverse drive 
gear. Such transmissions also include a neutral position in which no power 
is transmitted to the road drive wheels 72 and furthermore preferably 
include a park position in which the propeller shaft of the drive is 
locked. Such transmissions typically include an operating lever 74 movable 
to select park, reverse, neutral and other forward drive conditions of the 
transmission. 
In the illustrated arrangement, the power level of the engine is controlled 
by the vehicle operator by a suitable power request input 76 which is 
usually a foot throttle or actuator pedal of the vehicle. Ordinarily, in 
gas turbine controls, such an input 76 sets the speed or temperature level 
of the engine subject to limiting overrides of the power level as preset 
by the input 76. In the illustrated arrangement, the power request pedal 
76 actuates an N.sub.1 request transmitter 78 which transmits a signal of 
desired gas generator speed to a gas turbine engine controller 80. 
Furthermore, the controller 80 is associated with transducers or 
transmitters which provide signals indicative of various conditions of 
engine operation. Only those signals which are necessary for understanding 
the operation of the improved quick response pneumatic operator of the 
present invention will be disclosed herein. They include a gas generator 
turbine speed signal produced by an N.sub.1 transducer 82 which may be a 
suitable electronic or other tachometer having an amplifier 84 to deliver 
a potential proportional to gas generator speed to a line 86 serving as an 
input of this signal to the controller 80. Gas generator turbine inlet 
temperature identified as T.sub.4 is measured by a thermocouple or other 
suitable temperature sensitive means 88 located in the flow path from the 
combustion apparatus 22 into the high pressure turbine 18. Such 
temperature measuring devices ordinarily include an amplifier 90 that can 
include compensation for thermocouple temperature lag to establish an 
instantaneously corrected turbine inlet temperature directed through the 
line 92 as an indication of turbine inlet temperature to the controller 
80. A third input to the controller 80 is the temperature of the inlet 
portion of the exhaust path 28 as sensed by a temperature sensing device 
such as a thermocouple 94 that produces a temperature signal that is 
compensated for by thermocouple lag in a T.sub.6 amplifier 96 connected by 
an input line 98 to the controller 80 for overriding the power request 
signal transmitted by the request transmitter 78 through line 100 to the 
controller 80. 
The signal of line 100 is compared to the actual signal from the N.sub.1 
speed amplifier 84 to produce an error signal that is processed by 
controller 80 to produce an output signal therefrom through line 102 for 
controlling the amount of fuel flow through the fuel metering valve 30 to 
the combustor 22. Additionally, the controller 80 produces signals through 
lines 104, 105 that are directed to three-way control valve assemblies 
106, 107 to actuate them into selective mode positions for establishing 
the controlling action of quick response pneumatic operators 108, 110, all 
shown diagrammatically in FIG. 3. The pneumatic operators 108, 110 are 
coupled through linkages 112, 114 of a drive system 116 to operate a pair 
of flow control gate valves 118, 120 for regulating the gas flow through 
the power turbine nozzle 48 as will be discussed. 
Referring now more particularly to the flow control gate valves 118, 120, 
as best shown in FIG. 2, they are located within a storage space 122 
within the engine when in a retracted position. More particularly, the 
storage space 122 is defined by the inner wall 46 and axially spaced metal 
diaphragms 124, 126. The wall 46 includes an elongated slot 128 therein 
aligned with upwardly facing curved surfaces 130, 132 formed on the gate 
valves 118, 120, respectively, to fill the slot 128 when the gates are in 
a retracted position thereby to prevent any excessive flow of motive fluid 
from the flow path 42 to maintain efficiency during maximum flow control 
positions as shown in solid line in FIG. 2. Each of the gates 118, 120 has 
an upstanding stem 134 connected thereto of round cross section. Each stem 
134 extends through a circular hole 136 in the shroud 44 and thence 
through a layer 138 of thermal insulation surrounding the shroud 44. In 
the illustrated arrangement the surface of the shroud 44 is covered by a 
second thermal insulation layer 140 inboard thereof in facing relationship 
to the combustor 22 which is located within an air supply plenum 142 
formed in part by an upper layer of thermal insulation 144 covering an 
engine block wall 146. The engine block wall 146 has a bore 148 therein 
that receives an operator rod 150 extending through a hole 152 in a seal 
gland 154 at the upper end of bore 148. Gland 154 is held in place by a 
plug 156 threadably secured in wall 146. A bore 158 in plug 156 receives 
the upper end portion 160 of the operator rod 150 which extends outside 
the wall 146 as best shown FIG. 1. The upper end 160 of each of the rods 
150 is connected by a U-shaped link 162 having one end thereof directed 
through a pivot hole 164 in the end 160. 
Each link 162 has the opposite end thereof directed through a pivot hole 
166 in a side segment 168 of a U-shaped lever arm 170 with an opposite 
side segment 172 thereon. Each of the side segments 168, 172 has a bushing 
174, 176 directed therethrough, respectively, with the bushings 174, 176 
being freely slidably supported on the outer surface of a cross shaft 178 
of the drive system 116 as is best shown in FIG. 1. This arrangement 
enables the pneumatic operators 108, 110 to be located in close 
side-by-side relationship within a sheet metal housing 180 having a 
removable sheet metal cover 182 with louvers 184 struck in one end thereof 
to cool the interior 186 formed between the cover 182 and the housing 180. 
The housing and cover are held in place by a wing nut 187 and upright 
threaded stud 188 having a lower threaded end 190 threadably received in a 
tapped bore 192 in a boss 193 on engine block wall 146 as best shown in 
FIG. 1. Lock nut 194 fixes end 190 in place. 
Each of the quick response pneumatic operators 108, 110 includes a 
cylindrical support base 196 with connector studs 198 thereon that extend 
through openings in the housing 180 at a wall segment 200 thereof where 
they are fastened in place by nuts 202. 
As best shown in FIG. 1, each of the lever side segments 172 is in the form 
of a crank arm with a pivot point 204 thereon secured by a pin 206 to the 
outboard end of a reciprocal shaft 208 of each of the operators 108, 110. 
Each shaft 208 extends through an opening 210 formed by an inwardly 
directed tubular extension 212 on the base segment 196 as best seen in 
FIG. 3. The opposite end of each shaft 208 is sealingly secured to an 
annular lip 214 on a flexible power diaphragm 216. More particularly, the 
annular lip 214 is contoured at 217 to conform to an annular corrugation 
218 formed in a spring retainer 220 having a wall surface thereon seated 
on a shoulder 222 of the operator shaft 208. It is held in sealing 
engagement with the shoulder 222 by a struckover head 224 thereon in 
engagement with the outer surface of a diaphragm retainer plate 226 having 
its outer periphery in sealed engagement with the inboard surface 228 of 
the diaphragm 216 at the point where it extends outwardly of the plate 226 
and an annular flange 230 on the spring retainer 220. The spring retainer 
220 captures a large diameter end 232 of a coil spring 234 having the 
opposite end 236 thereof seated around the inboard surface of the tubular 
extension 212. The outer peripheral edge 238 of the power diaphragm 216 is 
held between an outer peripheral lip 240 on the cylindrical support base 
196 and a reversely turned edge on a cylindrical closure 244 that, along 
with the flexible power diaphragm 216, defines a pressurizable power 
chamber 246. 
Entrance to each of the controllers 108, 110 is through an inlet tube 248 
connected to the end of a closure member 250 that has a bent periphery 252 
thereon that clamps the diaphragm 216 to the outwardly directed end flange 
of the base 196. Additionally, each operator 108, 110 includes a pressure 
dump mechanism 254 thereon. Each of the pressure dump mechanisms 254 more 
particularly includes a bent armature plate 256 having a base segment 258 
thereon connected to the end of the closure member 250. It includes an 
outward extension 260 thereon that receives a bent end 264 on a movable 
flapper 266 of magnetizable material that includes a valve surface 268 
thereon selectively positioned with respect to an O-ring valve seat 270 
that is supportingly received in an undercut annular surface 272 formed in 
the end of a dump tube 274 having an inboard end 276 bent over into 
engagement with the inner surface of the closure member 250 to define a 
low volume exhaust passage 278 from the pressurizable chamber 246 of each 
of the pneumatic operators 108, 110. A solenoid coil 280 surrounds the 
dump tube 274 and is selectively energizable to either magnetically 
attract the movable flapper 266 into sealed engagement with the O-ring 
valve seat during normal controller operation. During a dump phase of 
operation, the solenoid 280 is deenergized thereby to cause the flapper 
266 to be pressure biased out of sealed engagement with the O-ring valve 
seat 270. Because of the low volume of the passage 278, the pressurized 
fluid in the pressurizable power chamber 246 is quickly directed to 
atmosphere by the bias of the coil spring 234 which produces a snap 
movement of the diaphragm 216 toward the closure member 250, thereby to 
quickly move the gate valves 118, 120 into their retracted solid line 
position as shown in FIG. 2. 
Each of the conduits 282, 284 has an orifice 286, 288 therein for 
establishing a control rate of pressure build-up within the pneumatic 
operators 108, 110. The conduits 282, 284 and orifices 286, 288 are 
connected by the valves 106, 107 to branch lines 289 and 291 of a fluid 
supply system 290 for association with the pneumatic operators 108, 110 
and operative to produce a controlled slow rate movement of the gate 
valves 118, 120 as will be discussed. 
Each of the three-way control valves 106 has a plurality of fittings 292, 
294 and 296 thereto. The fitting 292 is in communication with a regulated 
source of active control pressure 298 constituting the inlet to the supply 
system 290. Each fitting 296 is in communication with atmosphere across a 
control orifice 299. The fitting 294 is connected to conduit 282 or 284 to 
either pneumatic operator 108 or pneumatic operator 110. Each control 
valve 106, 107 includes a solenoid coil 300 that is selectively energized 
in response to signals from the output line 104 or output line 105 from 
the controller 80 to produce selective operation of either of the quick 
response pneumatic operators 108, 110. 
Operation of the controllers 108, 110 in a typical engine operating 
sequence includes conditioning them to place gate valves 118, 120 as shown 
in FIG. 2 as the spool 12 increases in speed from an idle speed to 50%-60% 
of design speed whereby the power turbine nozzle 48 is fully opened 
through a 360.degree. row of nozzle vanes 50. However, as the gasifier 
spool speed increases it has been observed that more thermally efficient 
operation can be obtained by selectively pulling one or both of the gates 
118, 120 upwardly into overlying relationship with flat surfaces 302, and 
306 on the leading edges of the nozzle vanes as shown in FIG. 2. More 
particularly, as the gasifier spool speed increases, a signal from line 
104 will condition the valve 106 to direct pressure from the source 298 
into the pneumatic operator 108 to cause an increase in pressure within 
the chamber 246 at a rate determined by orifice 286 which will cause a 
controlled rightward movement of the diaphragm 216 as shown in FIG. 3. 
This will cause the pivot point 204 to move in an arcuate path around the 
axis of the support shaft 178 and will thereby shift the control rod 150 
that is connected to the gate 118 in an upward direction. The rate of 
closure is reduced because of the control action of the orifice 286 so 
that the curved surface 130 will move across the gas flow passages between 
the flattened portions 302, 304 on the leading edges of the vanes 50 of 
turbine nozzle 48 to gradually reduce the total flow area through the 
turbine nozzle by an amount equal to the planar extent of the gate 118 
between its base 308, the curved surface 130 thereon and sides 310, 312 
thereof that join the curved surface 138 with the base 308. Eventually, 
the gate 118 is moved to a closed position where the curved edge 130 
engages the inner surface 52 of shroud 44. At this point the side 310 is 
pressed by motive fluid in flow path 42 into engagement with the flat 
surface 302 and the side 312 is seated in sealed engagement with the flat 
surface 304. The reduction in total flow area through the nozzle 48 
produced by movement of gate 118 is gradual and there will be a gradual 
power change that is accompanied by an increase in the inlet temperature 
of the turbine 18. This causes an increase in thermal efficiency and 
reduces specific fuel consumption of the engine. As engine speed continues 
to increase a second signal is directed through the line 105 to the 
three-way valve 107 to cause it to direct pressure from the regulated 
pressure source 298 to the inlet tube 288 of the pneumatic operator 110. 
Its power diaphragm 216 will be pressurized at a rate established by flow 
through orifice 288 to shift reciprocal shaft 208 outwardly in a direction 
to cause the rod 150 of gate valve 120 to move outwardly of the engine 
block wall 146 so that the curved surface 132 of gate valve 120 will move 
slowly to block the flow area between the flat surfaces 304, 306 on the 
turbine nozzle 48 until side edges 316, 318 on either side of gate valve 
120 are located in sealing engagement with the full vertical extent of the 
flat surfaces 304, 306. This completely blocks a second limited arcuate 
extent of the total flow area through the 360.degree. row of turbine vanes 
50. The remainder of the inlet passages between the vanes of the turbine 
nozzle 48 are unaffected by the control movement and a near complete 
annulus of gas flow (other than through the portion blocked by gates 118, 
120) freely flows from the flow path 42 through the nozzle 48 thereby to 
prevent any substantial change in the aerodynamic flow pattern of the flow 
path through the engine. 
The additional blockage of the nozzle 48 by gate valve 120 will further 
increase the inlet temperature of high pressure turbine 18 to produce 
greater thermal efficiency thereby to reduce the specific fuel consumption 
of the engine. 
In such turbine engine operation it is observed that as the T.sub.4 
temperature increases, the temperature into the regenerator, T.sub.6, as 
sensed by the thermocouple 94, may exceed desired limits. If this 
condition occurs, the signal in line 105 is modified to condition the 
control valve 107 to communicate the pressurized chamber 246 of pneumatic 
controller 110 with atmosphere across the orifice 299. The orifice 299 is 
sized so that pressure will be bled from chamber 246 to cause a slow 
retraction of the operating shaft 208 to the left as shown in FIG. 3. This 
will cause the gate valve 120 to be pushed downwardly by the control rod 
150 connected thereto to gradually increase the amount of gas flow through 
the power nozzle 48 to produce a gradual power change which will cause the 
turbine inlet temperature to be reduced. As the turbine engine inlet 
temperature goes down, the T.sub.6 temperature will follow to maintain 
modulated control of the T.sub.6 temperature produced in response to a 
slow movement of the gate valve 120 into its stored position within the 
storage space 122. If further thermal regulation is required, a like 
conditioning of the three-way valve 106 can occur to produce a like 
operation of the pneumatic controller 108 and gate valve 118. 
Thus, between idle and normal road speeds, (50%-60% of N.sub.1 engine 
design speed), both the gate valves 118, 120 are located in the storage 
position. When the spool 12 reaches approximately 60% of its full design 
speed, the speed of operation is that reached under normal road load 
conditions. Accordingly, the gates are operated to slowly increase power 
by movement into their blocking positions as previously discussed, 
preferably in a staged fashion, and this will increase the input 
temperature to the turbine and will result in a more efficient thermal 
operation with a reduced requirement for fuel. The gates 118, 120 are 
moved from their blocking position under such road load conditions only in 
cases where the increases in the temperature of the turbine increase to 
the point where the downstream temperature T.sub.6 into the heat exchanger 
26 exceeds an upper limit. At this point the control gates are adjusted 
between open and closed positions with respect to only a limited arcuate 
extent of the 360.degree. nozzle 48, again at a slow rate, because of the 
configuration of the improved pneumatic operators 108, 110 of the present 
invention and the associated fluid supply system 290. 
Another feature of the present invention is that the quick response 
pneumatic operators 108, 110 can be quickly conditioned through means of a 
single fluid connection to produce a quick movement of the gate valves 
118, 120 from the gas flow path if desired. One such operating condition 
is that which occurs when the power request pedal 76 is quickly rotated 
clockwise as shown in FIG. 1 to impose a large power demand signal through 
the input line 100 to the controller 80. At this point a large error 
signal is produced in the governing action of the controller 80 wherein 
the demand signal through the line 100 is compared with the actual speed 
N.sub.1 of the spool 12 directed to the controller 80 through the line 86. 
The error signal will produce an output signal on the line 102 for an 
increase in fuel to the combustor 22. This produces an immediate increase 
in the mass flow through the nozzle 36 to the gasifier turbine 38 to 
produce a speed increase in N.sub.1 and correction of the previously 
mentioned error signal. During this phase of operation the improved 
controllers 108, 110 are readily responsive to the increased mass flow 
through the gas flow path 42 of the engine to the nozzle 48 as follows. 
As the error signal is produced, an output signal is produced from an 
output line 314 to the solenoid 280 of dump mechanism 254 of operators 
108, 110 to cause flapper 266 therein to be shifted from a normally closed 
position where it is magnetized into sealed engagement with O-ring valve 
seat 270 to an open position (non-magnetized) to cause air dump to 
atmosphere through tube 274 to atmosphere. Accordingly, fluid will rapidly 
exhaust from each of the chambers 246. The volume of mechanism 254 is 
preselected to be small relative to that of chamber 246 so that there is 
an immediate dump to atmosphere from tube 274 and an immediate reduction 
of the pressure within the power chamber 246 to near atmosphere and the 
coil spring 234 snaps the reciprocal shafts 208 to the left as shown in 
FIG. 3 thereby to produce an immediate movement of the gate valves 118, 
120 into their storage position within the space 122. 
The advantage of such a quick response mode of operation is especially 
desirable in gas turbine engines of the aforesaid type. It has been 
observed that when the power request pedal 76 is rapidly moved to a full 
acceleration position to produce a maximum error signal that the increased 
fuel flow and increase in combustion products enables the gasifier to 
reach a maximum speed operation within one second. As soon as the gasifier 
directs such increased volumes of gas through the engine it is necessary 
to have a full open flow area through the power turbine nozzle 48 to 
prevent compressor surge. However, because of the quick response mode of 
operation of the pneumatic operators 108, 110, the nozzle 48 will have its 
full open area ready to receive the increased mass of fluid flow from the 
gasifier when it accelerates in response to large error signals produced 
upon a rapid movement of the power request pedal 76. 
The improved quick response pneumatic operators 108, 110 of the present 
invention are especially suitable for use with automotive type gas turbine 
engines in that they require only one fluid connection to each operator 
and an associated three-way valve to selectively communicate a control 
chamber of each of the operators to a regulated source of pressure to 
produce a slow rate controlled movement of gate valves under steady state 
conditions once the engine has reached a speed range of from 50% to 60% of 
its full design speed. The 50%-60% speed range produces a power output 
from the engine suitable for meeting most of the normal road load 
requirements for a gas turbine powered road vehicle. The pneumatic 
operators are further characterized by means internally thereof that 
permit a modulated slow rate control of the position of the gate valves to 
prevent excessive increases in turbine engine heat exhanger or regenerator 
temperatures following increases on engine turbine inlet temperatures that 
are produced by slow movement of the gate valves into a blocking position 
to reduce the gas flow area through the power turbine nozzle of the 
engine. And furthermore, the improved quick pneumatic response of the 
operators of the present invention are configured to be quickly responsive 
to a condition of operation that imposes a large error signal because of a 
power demand that is placed into the control to get more power from the 
engine if conditions require such additional power. In this case, the 
pneumatic operators quickly respond by means of internal components 
therein that cause the operator to be quickly dumped so that the gate 
valves connected thereto will quickly retract so that a full open flow 
path will be created within the engine in a time period that will prevent 
compressor surge as the gasifier spool is quickly accelerated in response 
to the error signal. 
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.