SE444030B - SET TO ADJUST THE FUEL FLOW TO A RECOVERATIVE GAS TURBINE ENGINE AND ENGINE THAT POSSIBLE EXECUTION OF THE SET - Google Patents

Description

~] EÉ ~ »~, ~ _» l 'öiszbsvos-o 2 ken. The gas stream coming from the gas generator at high speed and large volume normally drives the turbines at relatively high speeds. Other inherent characteristics of such gas turbine engines relate to the thermodynamic and aerodynamic processes carried out with the engines, which processes determine that the operating efficiency of each engine increases significantly with increasing maximum temperature of the gas flow.

These operating or operating characteristics of a gas turbine engine present certain disadvantages in comparison with what applies in the normal operation of internal combustion engines for ground vehicles with reciprocating pistons or with rotary pistons. More specifically, the ordinary internal combustion engine has the property of producing a considerable degree of deceleration effect for the vehicle when the fuel flow to the engine is reduced, in particular as a result of the braking force generated by the reciprocating part or parts of the engine. In contrast, the large moment of inertia of the gas turbine engine's turbines does not normally allow such instantaneous, relatively large deceleration power braking for a ground vehicle simply by reducing the fuel flow to the gas * turbine engine's fuel chamber. To try to overcome this disadvantage, a variety of suggestions have been made so far on how to \ | <; be able to increase the braking properties of a gas turbine engine as used; for propelling a ground vehicle. These ideas relate in principle to the complete extinction of the combustion inside the combustion chambers in order to achieve maximum dynamic braking. However, the operating life of a gas turbine engine is significantly reduced and the entire engine must continuously undergo a complete thermal cycle, which becomes the case when the combustion process is extinguished.

These attempts at constructive solutions also have an adverse effect on exhaust emissions. Other ideas relating to attempts to improve the dynamic braking properties of a gas turbine engine revolve around the use of a "fixed shaft" type gas turbine engine, the gas generator section and the power drive section being mechanically connected to each other to drive the vehicle. arrangement improves the dynamic braking, it also greatly reduces the engine usability iv in performing various other functions of driving a ground vehicle, and as a result has limited success in use as a power source for ground vehicles of the types An example of such a prior art design is disclosed in U.S. Pat. No. 3,237,404. The standard method of dynamic braking on gas turbine-powered aircraft, dwrs traction reversal, is of course not readily applicable when applies to ground vehicles.

Previously known arrangements for gas turbine engines for ground vehicles have also suffered from the disadvantage of not being able to achieve efficient and yet fast-reacting acceleration compared with what can be achieved with normal internal combustion engines with internal combustion. A free turbine engine has the inherent property that it normally requires a considerably longer time to develop the maximum torque required when accelerating the ground vehicle. Previous attempts to solve this problem have been concentrated on methods such as operating the gas generator at a constant, maximum speed, or have relied on other methods which are equally inefficient in the application of | utilize the fuel. On the whole, hitherto known 305 turbine engines for ground vehicles have normally suffered from reduced operating efficiency in attempts to improve engine acceleration or deceleration performance and / or have resulted in reduced efficiency by lowering the inlet temperature of the gas turbine engine turbine. have varied considerably, and this inlet temperature is a primary factor affecting the engine's fuel consumption. Furthermore, attempts made on the whole have proved to be insufficient to provide a reliable and reliable type of control system which is effective under all operating conditions of a gas turbine engine used to drive a ground vehicle fl h to provide safe , reliable operating characteristics. These previously known types of gas turbine engines have further resulted in reg \ Qf devices which entail significant changes in the action and the measures required of the driver in comparison with what applies when driving a vehicle with a conventional internal combustion engine.

Other problems related to previous attempts to achieve a gas turbine engine for ground vehicles have to do with the safety and reliability of the control system in various fault conditions, reliable and dependable types of control means, as well as the overall operating efficiency of the engine. A majority of these problems can be considered as a direct consequence or result of attempts to produce a gas turbine engine that offers operating characteristics that correspond to the desired, inherent functions of an internal combustion engine. làzoàvos-o 4 It is therefore easy to see that it would be highly desirable to provide a gas turbine engine and associated control means which include the desirable operating characteristics of both a gas turbine engine and a conventional internal combustion engine, and which also provide an economical end product. with a sufficiently reliable and safe construction to be used for ground vehicles that are to be manufactured in large series.

Discussions of exemplary known constructions relating to the same basic type of engine as the present invention are found in the aforementioned US-A-3,237,404 and US-A-3,660,976; 3,899,877 and 3,941,015, all of which appear to relate to proposals for transferring drive power from the gas generator to the engine output shaft, and US-A-3,688,605; 3,771,916 and 3,938,321 relating to other ideas for the performance of vehicle gas turbine engines. Examples of proposals for variable outlet nozzle motors are also found in US-A-3,686,860; 3,780,527 and 3,777,479. Prior art fuel control regulators of the general construction type contemplated by the present invention are found in US-A-3,400 S35; 3 SO8 393; 3,568,439; 3,712,055; 3,777,480 and 3,913,316, of which, however, none disclose any means of restoration and offset control as contemplated by the present invention; and US-A-3,521,446 which discloses a considerably more complicated embodiment for fuel recovery than that encompassed by the present invention. Examples of other fuel control devices that are less relevant to the present invention are found in U.S. Patent Nos. 3,851,464 and 3,888,078. the present invention, while U.S. Patent 2,976,683; 3,183,667 and 3,820,323 relate to control means for setting valves.

An essential object of the present invention is to provide an improved gas turbine engine and a method of regulating the fuel flow to the engine combustion chamber, the gas turbine engine being such that it exhibits desirable characteristic operating characteristics which normally apply to piston engines.

Another essential object is to provide a gas turbine engine with facilities which result in improved fuel economy in a variety of driving conditions for ground vehicles powered by such a gas turbine engine.

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Vnàuæmmvecklhxæm av «gasbnå fl nmoun: 1enligtuqçiinnhxnaxkan dessmumxha de särdraqamsan specified in claims 4-21 represent various essential aspects of mmæxncmixdesstdlntkanåareghaxngan.

The engine can thus, for example, suitably constitute a recuperative free turbine engine with separate gas generator and power turbine sections.

A fuel regulator then controls the fuel flow to the fuel chamber to adapt the speed of the gas generator to the setting of the throttle control. Reset electromagnets can balance or overcome this control and adjust the fuel flow depending on certain operating parameters or operating conditions of the engine in operation. For example, in response to low speed of the output shaft from the drive transmission clutch, which low speed is an indication of an imminent desired engine acceleration for increased output torque, a reset electromagnet causes the fuel flow and the gas generator idle to increase. to significantly reduce the time required to increase engine output torque. An adjusting valve is effective in regulating the fuel flow during engine acceleration to prevent an excessively high recuperator inlet temperature and maintain the turbine inlet temperature at a substantially constant, high level to achieve maximum engine performance. The setting valve reacts to the combustion chamber inlet pressure and temperature, and also controls the flow of fuel during deceleration in a way that maintains combustion. Adjustable turbine guide rails are first adjusted to provide maximum power to the gas generator during its acceleration, and then adjusted in the direction of a position which means delivering maximum power to the power turbine section. The variable guide rail control comprises a hydromechanical part with the ability to regulate the speed of the power turbine section depending on the position of the throttle control, and has an electromechanical part which cooperates with it to set the guide rails in a braking state for deceleration.

Power feedback is set up to achieve even greater and thus better braking properties. When braking is to be effected, the speed of the gas generator is automatically adjusted so that it approaches the speed of the power turbine, and by means of a coupling with a relatively low mark- ef fi adzär gasgaæmabar-cch.ef szosvos-o engine output shaft.

These and other objects and advantages of the present invention are described in or will become apparent upon study of the following detailed description of a preferred embodiment when this description is studied in conjunction with the accompanying drawings.

For the drawing figures, it follows that: Fig. 1 in perspective view shows a gas turbine engine with associated drive transmission, in accordance with the principles of the present invention; Fig. 2 is a perspective view of the power feedback drive transmission included in the engine, showing parts of the engine in outer contour; Fig. 3 shows a partial, partly schematic longitudinal section through the power feedback coupling with associated hydraulic system, which section is taken at lines 3-3 in Fig. 2; Fig. 4 shows a partial, schematic cross-sectional view of the rotating group of the engine with associated control devices shown in schematic block diagram form; Fig. 5 shows in perspective view a portion of the engine housing, conductive passages and combustion chambers with certain parts omitted so that the inner parts of the structure should be more clearly visible; Fig. 6 shows a partly schematic, plan sectional view of the fuel regulator 60 with certain parts shown in perspective so that the functional connections will be clearer; Fig. GA shows an enlarged, partial cross-section of the fuel pump, which section is taken on the whole along the lines GA-GA in Fig. 6; Figures GB, GC and 6D show enlarged cross-sectional views of a portion of the fuel regulator control, showing different operating modes of the electromagnet 257; Fig. 7 is a schematic, perspective view, functional representation showing the setting valve 62 in section; Fig. 8 shows a cross section through a portion of the setting valve; Fig. 9 is a cross-sectional view of the setting valve, which view is taken generally along lines 9-9 of Fig. 8; Figures 10 and 11 are enlarged views of portions of the valve 282 showing the interconnection of fuel metering passages as would appear along lines 10-10 and 11-11, respectively, in Fig. 7; Fig. 12 is a schematic, sectional view of the guide rail control 66; Fig. 13 is an "exploded" perspective view of the guide rails and the link arm system of the adjusting member; Figures 14, 15 and 16 are circumferential views showing different operating connections between the adjustable guide rails and the power turbine blades; Fig. 17 is a schematic logic representation of a portion of the electronic control module 68; Fig. 18 is a graphical motor diagram of the area ratio of the power turbines as a function of guide rail angle; Fig. 19 is a graphical representation of the desired speeds of the gas generator section and the power turbine section selected in relation to the throttle control position; and Fig. 20 is a graphical representation of the relationship between the fuel flow permitted by the setting valve as a function of the combustion chamber pressure along constant combustion inlet temperature lines.

Referring to the figures, the abbreviations used in the detailed description below to denote various parameters are listed below: Npt - the power turbine 54 speed Ngg '= the speed of the gas generator 52 Nggu - the preset speed of the gas generator 52 Nti - the transmission input shaft 36 axis 36 Wf = fuel flow BI stator guide rails 120, 122 angle B * - predetermined stator guide rail angle a = setting (position) of throttle control 184 a * - predetermined throttle setting T2 - compressor inlet temperature P2 = ambient pressure T3_5 burner combustion chamber combustion chamber pressure T¿ - turbine inlet temperature TG - turbine outlet temperature Reference is now made more particularly to the drawings which show an improved gas turbine engine which is of the type contemplated by the present invention and which is generally designated 30.

As shown in Fig. 1, the engine is connected to a substantially standardized drive transmission for a vehicle, especially a truck in the power class 450-600 hp, with a power output shaft 32 as the input part to a drive transmission clutch 34. A transmission input shaft 36 extends between the clutch 34 and a multi-gear type of transmission 38. The transmission 38 is of that on manual,: =, ~ ,,; _; ,,,, _ W¿¿, §. », _, V» i v- m. .M. _ i. i 8 2 0 5 7 0 S - 0 8 path interchangeable type; however, it is to be understood that various improvements of the present invention are equally useful in conjunction with other types of speed varying transmissions. In a conventional manner, the transmission 38 has a plurality of different positions including several forward gears, reverse gear and a neutral position. In the neutral position, no power is transmitted between the transmission's input shaft 36 and the transmission's output shaft 40, which conventionally extends to the rear axle gear 42 and the vehicle's drive wheel 44. A manual gear lever 46 provides the desired gear selection, and a speed sensor 48 generates a signal showing the speed of the input shaft 36 of the transmission. As schematically shown in Fig. 1, and described in more detail below, the speed sensor 48 may be of any suitable type which can be combined with the control medium of the engine 30. The speed sensor 48 instead generates an electrical signal which is transmitted via the line 50 to the electronic control module of the motor.

Reference is now made to Figures 1-4 from which it appears that the engine 30 is of the recuperative free turbine type, and comprises a gas generator section 52, a power turbine 54 mounted on a shaft separate from the shaft of the gas generator 52, and a recuperator S6 which extracts waste heat from the exhaust stream from the engine, in order to preheat the compressed fluid before it participates in the combustion process. The engine generally further comprises a source 58 of combustible fuel, a fuel regulator generally designated 60 and which includes the fuel pump, a setting valve 62 for regulating the flow of fuel normally under acceleration or deceleration of the engine through a fuel line 64 which extends to the gas generator section S2, and a variable position control 66 of adjustable stator guide rails included in the power turbine section 54. An electronic control module 68 receives and processes various input parameter signals and generates output control signals for the controller regulator 60 and guide means. 66.

Conventionally, an electric accumulator battery 70 and an associated starter motor 72 are also included, which are preferably selectively coupled to both the gas generator S2 and a starting air pump 74. During start, the motor 72 is powered to drive both the starting air pump 74 and the main shaft 76 of the gas generator. As shown in Fig. 2, the preferred embodiment of the invention also includes a drive transmission 78 connected to the gas generator shaft 76, and another drive transmission 80 connected to the main shaft 82 of the power turbine 54. The two and 80 are selectively interconnectable wet clutches which is generally designated 84 relatively low power. This coupling is power feedback coupling, and its closely related to and driven the drive transmissions 78 with each other by one and which is intended for the general type of reconstruction are described in detail below with reference to Fig. 3, while its functional operation is described even further below. description in connection with the description of the power feedback drive in accordance with the present invention.

The gas generator 52 generally comprises a suitably filtered air intake 86 through which ambient air is supplied to a pair of centrifugal compressors 88 and 90 arranged in series. The transition duct portion 92 directs the flow of compressed air from the first compressor 88 to the second compressor 90. In the gas generator 52 further includes the duct portion 94, shown in Fig. 5, which surrounds and traps the outgoing stream of compressed air from the circular circumference of the second stage compressor 90, and directs this flow of compressed air through a pair of feed channels 95 to the recuperator S6 in non-mixing, heat exchanging connection with the recuperator. Various types of recuperator designs can be used in conjunction with the present invention, and an example of such a type is described in U.S. Pat. No. 3894S81. Although not necessary to understand the present invention, reference is made to the latter U.S. patent for a detailed description of a recuperator and its operation. For an understanding of the present invention, it is sufficient to note that the flow of compressed air from the ducts 95 is preheated in the recuperator by means of the waste heat from the exhaust gas flow of the engine. The preheated compressed air stream is then passed through the duct 96 to a "can type" combustion chamber 98. As best seen in Figure 5, the heated flow from the recuperator passes through a plurality of openings 97 into a pressure portion of the channel 96, then through openings 97A in a portion of the housing structure that supports the combustion chamber 98. The combustion chamber 98 has a perforated interior. insert or a flame tube 99, and the air flow from the openings 97A passes into the zone between the inner and outer insert and then passes through the perforated inner insert or flame tube 99 into the combustion chamber zone. One or more electric spark plugs 100 are suitably connected in a conventional manner to a high voltage source. The spark plug is drivable to; ¿u; Maintaining a continuous combustion process in the interior of the combustion chamber, in which the fuel supplied through the conduit 64 is mixed and combusted together with the compressed air flow from the duct 96. The gas generator 52 further comprises a radial actuator type gas generator turbine 102. . The flow of the compressed heated gas from the combustion chamber 98 is discharged over the turbine inlet throttle nozzles 104, located in a circular arrangement around the annular inlet 106, to the turbine section of the gas generator. When the engine is running, the nozzles 104 maintain the pressure in the combustion chamber 98 at a value higher than the ambient pressure.

Flow of this heated compressed gas over the turbine 102 causes high speed rotation of the turbine and the main shaft 76 of the gas generator.

The power turbine section S4 generally comprises a duct section 112 and suitable guide rails 114 arranged therein for directing the gas flow from the power generator 102 of the gas generator towards a pair of axial power turbines 116 and 118 mounted on the main shaft 82 of the power turbine. The power turbine section further comprises 120 and 122 of variably adjustable guide rails arranged upstream of thus coordinated axial turbines 116 and 118, respectively, and these. turbines 117 and 119, respectively. As shown in Fig. 13, each of the sets of variable guide rails 120 and 122 is located in an annular set within the gas flow path, and both sets are connected to a common actuating mechanism, generally designated 124. Actuating mechanism 124 comprises a pair of crown wheels 126 and 128, a wheel for each set of adjustable guide rails, a link 129 attached to the crown wheels 126 and attached to the crown wheel 128 via the plate 129A. An angle lever 130 is pivotally mounted to the housing, and a twisted link 131 has its opposite ends pivotally connected to the link 129 and to one arm of the angle lever 130. A linearly displaceable input shaft 368 acts through a hinge link 132 and the second arm of the angle lever to cause pivot of the lever 130 about its axis 133, and consequently simultaneous rotation of both crown wheels 126, 128. Movement of the input shaft 368 causes rotation of each of the crown wheels 126,128 about an axis coinciding with the axis of rotation of the driven shaft 82, to provide unison 8205705-0 11 Eotation of the two sets of guide rails to different positions in relation to the direction of the gas flow passing between them.

As shown in Figures 14-16, the guide rails 120 are set in a central or "neutral" position in Figure 14, which causes substantially maximum area ratio and minimum pressure ratio across the turbine wheel 116 downstream of the turbine wheel vanes 117, to minimize the effect of the gas flow. is transferred to rotation of the turbine 116. The position according to Fig. 14 is graphically shown in Fig. 18 by means of the position which is arbitrarily denoted 0 °. The guide rails 120 are variably adjustable to the position shown in Fig. 15, which is indicated in Fig. 18 + 20 °, whereby high pressure ratio prevails over the vanes 117 and maximum power is transmitted from the gas flow to the turbine 116 to rotate transmit maximum power to the shaft 82. The guide rails are also pivotable in the opposite direction to the position shown in Fig. 16, which in Fig. 18 is denoted -950, the gas flow being directed by means of the adjustable guide rail axes 120 so that it acts and strives to decelerate. - lets 116 rotation. Although only guide rails 120 and vanes 117 are shown in Figures 14-16, it should be apparent to those skilled in the art that substantially identical operating relationships exist between the guide rails 122 and the turbine 118 turbine vanes 119.

When the gas stream has left the last axial turbine 118, it is combined in an exhaust duct 134 leading to the recuperator 56. The output shaft 82 of the power turbine forms part of or is operatively connected to the engine output shaft 32 by a suitable speed reducing gear. An air or water cooler 87 is also included and is adapted to cool the lubricating fluid in the engine 30, and communicates with the fluid container 89 via the hose 91.

Fuel regulator 60 Reference is now made more particularly to Figures 4, 6, 6A-60, which show that fuel regulator 60 receives fuel A: 1 from source 58 via a suitable filter 136 into an inlet port. 138 to a fuel pump housing 140. It should be apparent to one skilled in the art that the housing 140 is attached to and may be integral with any other portion of the main engine housing 110. through either of the output channels 142, 144 for forwarding to the setting valve 62. The regulator 60 is hydromechanical in nature, but is capable of responding to externally applied mechanical and electrical signals, and includes a suitable drive connection schematically indicated by the line 146, and an associated speed reducing gear 148 required to drive a gear 150 and the drive shaft 152. The drive shaft 152 drives a fuel pump in the form of a positive displacement pump which is a gear pump 15 , which receives fuel from the inlet port 138 and delivers the fuel at a substantially higher pressure via an outlet line 156. As is clear from Fig. 6A, the the gear pump engages a pair of interlocking gears 158 and 160, one of which is driven by the drive shaft 152 while the other is mounted on a non-driven shaft 162 mounted in the housing 140. From the outlet line 156 three passages are fed in parallel flow, dwrs the outlet channel 142, the bypass bore 164 and the main flow measurement passage 166. The bypass bore 164 houses a bypass control cylindrical valve member 168 which is slidable within the bore 164 to variably dose excess flow from the outlet line 156 to a return passage 170, which is fed back to the fuel inlet port 138. Fuel pressure in the bore 164 presses the valve member 168 in a downward direction to increase bypass flow through the passage 170, while a compression spring means 172 acts in the opposite direction to the fuel pressure to push the valve member 168 upward to reduce volumetric flow. bore 164 to passage 170.

Via a pressure passage 182, the lower end of the bypass bore 164 communicates with the fuel supply line 64. The pressure of the fluid in the line 64 is thus effective on the underside of the bypass valve member 168 to assist the spring 172 in resisting the force generated by the high pressure fluid. in the output line 156.

The passage 166 terminates in a metering or measuring nozzle 174 which is attached to the housing by means of the plate 176, and has a reduced diameter opening 178 which communicates with a central cavity 180.

The fuel regulator 60 further includes a manual throttle control input in the form of a throttle control arm 184 adjustable between opposing adjustable stops 186, 188 which are adjustably attached to the housing 140. Through a suitable bearing 190 is a shaft 192 extending within the inner cavity 180. rotatable relative to the housing 140. Supported by and made integrally with the shaft 192 is a side open cam section 194, in which by means of a press fit a pair of shaft pins 196 are attached - each supporting its own roller 198.

The rollers 198 are arranged to be in contact with a lower shoulder * szosvos-o 13 on a spring stop 200, so that pivoting of the throttle control arm 184 and thereby rotation of the shaft 192 results in a concomitant rotation of the shaft pins 196 which are not in line with the center line for the shaft 192, thereby obtaining vertical adjustment of the spring stop 200 through the rollers 198. During its vertical or longitudinal adjustment, the spring stop 200 is guided by a guide shaft 202 having an upper guide pin 204 extending slidably through a central hole in the spring stop 200. The guide rod 202 is screwably received and by means of, for example, the lock nut 206 fixed to the housing 140.

The controller 60 further includes a mechanical speed sensor that includes a centrifugal weight holder 208 that is fixedly mounted to rotate together with the shaft 152. Together with the holder 208, a plurality of evenly distributed and spaced apart centrifugal weights 210, which are mounted for pivotal rotation about pins 212, rotate. holds the weights 210 at the holder 208. Depending on the shaft speed 152, the centrifugal force causes the weights 210 to pivot about the pins 212, so that the inner ends of the weights are displaced in the downward direction, as seen in Fig. 6, and drives the inner rotating bearing race. 214 of a rolling bearing also in the downward direction. Through the ball bearing 216, this downward force is transmitted to the non-rotating outer bearing race 218 of the bearing, thereby causing downward displacement of the non-rotating segment 220. At its lower end, the segment 220 carries a spring stop shoulder 222, and a spring 224 is operative. arranged between the segment 222 of the segment 220 and the spring stop 200, which is connected to the throttle control input mechanism. Through a bias from the spring 224 acting on the segment 220, the centrifugal weights are normally kept pushed upwards to the zero position shown in Fig. 6 or the position corresponding to a low speed. An increase in the speed of the shaft 152 causes a downward displacement of the segment 220. It is therefore recognized that the throttle control arm 184 substantially acts to select the throttle generator speed as reflected by the shaft 152 speed, since the compression of the spring 224 is adjusted by the pivot of the throttle lever 18 and the centrifugal force generated by the rotation of the shaft 152. The vertical setting of the segment 220 will therefore be an indication of the difference between the selected speed (setting position of the input gas control arm 184) and the actual gas generator speed as sensed by the centrifugal weights.210. ., gߧ§gg4 .., ¿§§ffn} t $ ä »4f * '~ .NV' v» “r ~ e 8205705-0 14 Fig 19 shows the spring: 224 effect when it comes to requesting different levels of gas generator speed N 9, when the throttle control is moved between different positions a.

The regulator 60 further includes a main fuel gas control arm 226 which is pivotally mounted to the housing 140 by the pin 228. An arm 230 of the lever 226 terminates in a spherically shaped end 230 in a receiving groove 232 on the segment 220 of speed error signal. the mechanism. An opposite arm 234 of the lever 226 is movable toward and away from the metering port 178 in response to displacement of the segment 220 to thereby variably dose the fuel flow from the passage 166 into the inner cavity 180. It will be appreciated that the control valve member 168 is variably adjustable in response to the pressure difference between passage 168 and conduit 64 downstream of metering port 178, to variably dose bypass fluid flow through passage 170 to maintain a substantially constant pressure difference across the fluid metering port generated between the dosing opening 178 and the arm 234 of the fuel lever 226. The magnitude of the fuel flow supplied from the passage 166 to the cavity 180 and the outlet channel 144 thus constitutes a function only substantially of the position of the arm 234 relative to the dosing opening 178 as soon as it constitutes the fuel flow regulating parameter. If appropriate, a damping opening 236 may be provided in the pressure sensing line 182 to stabilize the movement of the bypass valve member 168.

A unidirectional, proportional electromagnet 239 has an outer housing 238 integral with the plate 176 or otherwise secured in a stationary relationship to the housing 140. Inside the housing 238 is located a coil 240, and a centrally located armature 242.

Fixed to form a portion of the armature 242 is a central plunger shaft 244, so having an upper end which can be brought into contact with the lever 234. Linear springs 246, 248 are operatively arranged to extend between stop means on the housing 238 to be in contact with associated projections on the plunger shaft 244, to normally press the latter to its deactivated position as shown. Activation or current supply of the electromagnet by suitable electrical leads 250 causes upward displacement of the armature 242 and the plunger shaft 244, so that the latter is brought into contact with and exerts an upward force on the lever 234, which force acts in the opposite direction to and is subtracted. from the force exerted by the spring 224 on the lifting arm 226.

Although the plunger shaft 244, if desired, could be in direct contact with the lever 234, in the preferred embodiment an arrangement for the army 234 is used which involves a "floating contact surface". In this arrangement, a floating flat plate surface 252 is supported in the arm 234 axially opposite the dosing opening 178. This "floating" surface is normally spring loaded in the direction of the dosing opening, and the upper end of the plunger shaft 244 can be brought into contact therewith. The purpose of the liquid surface 252 is to compensate for manufacturing tolerances and to ensure that a relatively flat surface is located directly in the middle of the metering port 178 and extends perpendicular to the fluid flow from said port to ensure proper metering of fuel across the port. . The spring 254 loads the floating surface 252 in the direction of the opening 178. Swinging of the arm 234 against the force_from the spring 254 to increase the fuel flow is allowed until the surface 252 comes into contact with the upper end 245 of the plunger shaft 244. This stroke movement for the arm 234 is very limited but large enough to provide flow saturation for the annular opening defined between the opening 178 and the surface 252.

On the side of the lever 234 opposite to the electromagnet 239 is arranged a housing 256 for another directional one-way electromagnet 257, as shown in Figures 68-60. The electromagnet 257 contains a coil 258, an armature 260, and a plunger shaft 262. which is attached to the anchor to move along with it. By means of suitable stop means, centering springs 264, 266 normally push the plunger shaft 262 to the deactivated position shown. Upon actuation or power supply of the coil 258 via suitable conduits 268, the armature 260 and the plunger shaft 262 are displaced in the downward direction so that the plunger shaft comes into contact with the lever 234 in such a way that a force is exerted on the arm, which force adds to the force is generated by the spring 224 and causes pivoting of the lever 226 to displace the arm 234 away from the opening 178. The housing 256 of the electromagnet 257 is fixedly attached to the mounting plate 176, for example by means of bolts 270. Similarly to the floating surface 252 applies to the preferred the embodiment that the plunger shaft 262 is not in direct contact with the lever 234, but instead acts via a "floating bearing" pin 272 to exert a force on the arm 234. The pin 272 is biased by a spring 274, to provide buoyancy and thereby ensure that the plunger shaft 262 can be brought into proper contact with and exert a force on the lever 234 regardless of variations in manufacturing tolerances, and / or independent of the position of the lever 226 relative to its pivot axis 228.

Both electromagnets are kept pressed to their deactivated positions by means of springs with a linear gradient, and in contrast to digital electromagnets of the on-off type, variations in the input current and / or the input voltage to the coils of the electromagnets will produce a analog change setting of the plunger shaft 244 in the electromagnet 239 and thus move the plunger shaft 262 to its position shown in Fig. 6C or Fig. 6D.

The plunger shaft 262 of the electromagnet 257 can be displaced away from its deactivated state shown in Fig. 68 to two different activated states, as shown in Figs. 6C and 6D. An electrical input signal of predetermined intermediate strength causes the armature 262 to be displaced to the position shown in Fig. 6C, thereby moving the plunger shaft 262 until the surface of its adjustable stop nut 263 is brought into contact with the spring stop 267. This movement of the plunger piston 262 compresses the plunger shaft 27 the spring 274 to move the arm 234 away from the opening 178 and increase the fuel flow until the gas generator speed has increased to a level corresponding to the signal force generated by the electromagnet 257. The construction of the plunger shaft 272 and the spring 274 thus helps to allow a power signal smaller than the maximum to produce a force acting on the arm 234 and having a certain predetermined magnitude.

Another electrical input signal of greater strength causes the armature to be displaced to the end of its kind, its surface 261 coming into contact with the adjacent stop surface 259 of the housing 2S6, as shown in Fig. 60; This movement causes the plunger piston 262 to compress the centering spring 266, and causes the lower end of the plunger piston to be brought into direct contact with the arm 234, forcing it to allow maximum flow through the opening formed between the opening 178 and the piston 252.

As described in more detail below, driving the electromagnet 257 to its activated position shown in Fig. 6D substantially means a false throttle control signal which doubles the speed desired from the throttle generator when the throttle is depressed or adjusted to its low corresponding fuel flow. and thus maximum effect. The setting valve 62 is now more particularly referred to Figures 7-11, which show the setting valve 62 which generally comprises a housing 276 which may be integral with both the housing 140 and the stationary motor housing 110. The housing 276 is preferably arranged close to adjacent to both the fuel regulator 60 and the combustion chamber 98.

The housing 276 includes an inner bore 278 into which the two fuel lines 142, 144 as well as the fuel line 64 and a low pressure return line 280, which returns fuel to the source or storage, open. Inside the bore or bore 278, a metering valve 282 is provided for longitudinal displacement and rotation, and this valve 282 has "window-like" irregularly shaped openings 284, 286 which open into the hollow inner cavity 288 in the valve 282. The fuel line 144 is continuously connected to the inner cavity 288. The valve 282 further comprises an opening 290 in continuous connection with the fuel line 64. The deceleration window 286 is generally arranged in the middle of the fuel channel 142, and the acceleration window is on the generally located in the middle of the opening 290. The special design of each of the windows 284, 286 is clearly shown in Figures 10 and 11.

The metering valve 282 is pressurized in one longitudinal direction by means of a biasing spring 292 which abuts the housing 276 through a spring stop 294 which acts on an alignment point 296 of a sealed block 298 mounted in the housing 276 for example by the locking ring 300. The preferred construction is shown in Fig. 9. ; the focus point arrangement which allows rotation of the valve 282 in front of the housing or the spring 292 can, however, alternatively be provided by means of an arrangement with a ball 302, as schematically shown in Fig. 7. At the opposite end of the valve 282 there is a spherical ball 304 which allows rotation of the valve 282 relative to a piston 306 received in the bore 278.

Connected to the housing 276 is a temperature-sensitive element 312,308, for example a thermally reactive cylinder, the longitudinal dimension of which. . varies depending on the temperature to which it is subjected by the gas or other fluid present in the temperature sensitive chamber 310 inside the cylinder 312. The housing 276 is so mounted in relation to the engine that a portion thereof, especially the cylinder 312- 'iiezosvos -Q 18 ßch the associated chamber 310, communicates with and maintains at the same temperature, T3_5, as the stream of compressed air which: is introduced into the combustion chamber. Thermally insulating material 311 is also included when required to avoid overheating of the valve 62. The right end of Fig. 9 and the perforated cylindrical wall 312 may, for example, be provided at the air inlet to the combustion chamber and / or at the duct 96. , which conducts air from the recuperator S6 to the combustion chamber 98. In any case, the setting valve is arranged so that the cylinder 312 expands and contracts longitudinally with regard to increasing and decreasing the inlet temperature of the combustion chamber. The valve 288 is operatively actuated by the thermally responsive element 312 by a relatively non-thermally responsive ceramic rod 308. Consequently, the valve 288 is displaced longitudinally relative to the inlet port 142 and the opening 290 relative to the sensed combustion chamber inlet temperature. The metered fuel flow maintained by the window 284 is thus varied in relation to the sensed combustion chamber inlet temperature when the said window is moved longitudinally relative to the opening 290.

The housing 276 further includes a transverse bore 314 disposed transversely and intersecting the longitudinal bore 276. A rod-piston structure 316 is provided for longitudinal reciprocating movement within the transverse bore 314, and this structure includes a pair of seals 318 , Membrane type 320, which seals have outer ends fixed to the housing 276 by being clamped between the housing, an intermediate section 322 and a closure plug 324 which is screwable or otherwise attached to the housing 276. The inner ends of the seals 320 are attached to the movable piston rod structure 316. Together with the end closure plug 324, the seal 320 defines an internal pressure sensing chamber 326 to which one end of the piston 316 is exposed. Through a sensing line 328, the combustion chamber: pressure P3_5, for example the inlet pressure of the combustion chamber, is transmitted to the interior of the chamber 326 to act on one end of the piston 316. At the opposite end of the bore 314 a spring element 330 is designed as a biasing coil spring. abuts the housing 276 via a stationary stop 332, arranged to push the piston-rod structure 316 in the opposite direction to the direction of pressure obtained by the pressure in the chamber 326.

The opposite end 334 of the piston structure 316 is vented. Wi 9 azosvos-a 19 Quill the atmospheric pressure via a suitable port 336. A seal, schematically shown at 335, which may have a structure similar to the seals 318, 320 and section 348, is also provided at the opposite end 334. The overpressure in the combustion chamber, dirs the difference between the ambient pressure and the absolute pressure maintained in the combustion chamber 98, acts on the piston 316 to displace it within the bore 314.

An arm 338 is threadedly attached at one end within a transverse bore in the metering valve 282, and at its other end the rod 338 has a spherical ball 340 received in a groove 342 in the rod-piston structure 316. From this it will be appreciated that Pushing of the piston rod assembly 316 within the bore 314 is transmitted to rotation of the metering valve 282 about its main longitudinal axis. Accordingly, the respective openings between the windows 284,286 and the inlet ports 142 and the opening 290 are also varied in relation to the magnitude of the overpressure in the combustion chamber 98 due to said rotational movement of the metering valve 282.

The groove 342 allows axial displacement of the arm 338 along the valve 282. Although the rod-piston structure 316 may be embodied in various ways, the preferred embodiment shown in Fig. 8 includes a threaded end section 344 which by suitable means 346 is effective in compressing and clamping the inner ends of the seals 318, 320 to the rod 316 by means of an intermediate section 348.

The setting valve thus functions as a mechanical, analogous calculation unit that multiplies the parameters consisting of the combustion chamber pressure, P3_S, and the combustion chamber inlet temperature, T3_5, so that the position setting of the valve 282 and the windows 284, 286 becomes a function of the product of the combustion chamber pressure combustion chamber inlet temperature.

As shown in Fig. 4, the control means for the engine 30 further comprises in a conventional manner a normally open electromagnet-operated fuel sequence solenoid valve 350 as well as a manually or electrically electrically operated shut-off valve 352. These valves are located downstream of the setting valve 62, and in the preferred embodiment, may be included in and / or be arranged adjacent to the housing 276 of the setting valve 62.

The design of each of the windows 284, 286 shown in Figs. Pa.s * '(3115 where: K1, K2 and X3 are constants which are determined by the operating characteristics of a particular gas turbine engine and which are reflected by the design of the window 284 and the associated opening 290.

By properly designing the window 284 and the opening 290, the solution of this equation, as obtained by the setting valve 62, ensures that a constant maximum turbine inlet temperature T4 is maintained during all or at least part of the acceleration of the gas generator. Accordingly, when the window 284 is the regulating parameter of the fuel flow, the setting valve 62, empirically by a mechanical analogy, regulates the fuel flow to maintain a substantially constant turbine inlet temperature T4. Window 284 is the primary operating parameter during engine acceleration, as described in more detail below. In contrast, window 286 is the regulating parameter during engine deceleration.

While the acceleration window 284 is designed to maintain a substantially constant maximum inlet temperature for the gas generator turbine to achieve maximum acceleration performance within the engine temperature limits, the deceleration window 286 is designed to restrict and control the fuel flow to prevent combustion from occurring while the combustion occurs. A detailed discussion of the operation of a similar type of turbine inlet temperature calculating valve, which valve, however, uses the absolute pressure of the combustion chamber rather than its overpressure, is found in U.S. Pat. No. 4,057,960.

Guide guide actuator 66 Details of the guide actuator actuator 66 are shown in Figures 12 and 13. This guide rail control means is hydromechanical in nature and generally comprises a housing 354 with a pair of hydraulic pressure fluid supply ports 356, 358 which receive pressure fluid from a high pressure pump source 360 and a low-pressure pump source 362, which pump sources are both driven by the engine auxiliary power system. It is understood that the pumps 360, 362 may also have various other functions in the motor, for example the task of providing lubrication.

The housing 354 has an inner fluid receiving cylinder 364 in which a piston 366 is arranged to be movable back and forth, which piston divides the cylinder into opposing fluid pressure chambers. The rod or shaft 368 carried by the piston 366 extends out of the housing 354 and is operatively connected to the angle lever 130 shown in Fig. 13 so that, as previously described, linear reciprocating motion of the rod 368 causes pivoting of the angle lever 130, rotation of the crown wheels 126, 128 and thus the sets of adjustable guide rails 120, 122.

High pressure hydraulic fluid from the inlet port 356 is fed into a bore 370 inside the housing 354, the latter bore being located adjacent the cylinder 364. The bore 370 is also cut at mutually different locations by a high pressure fluid outlet channel 372 and a pair of working fluids 37. , 376 which respectively communicate with the cylinder 364 on opposite sides of the piston 366. A directional fluid control valve element 380 is arranged for reciprocating movement inside the bore 370, and this element 380 is normally adjustable in the open center position shown, the high pressure hydraulic fluid from the channel 356 only communicating with the drain port 372.

A series of centering springs 382, 383, 384, 385 normally push the valve 380 to the position shown. the valve 380 is of the four-way type and is adjustable in a direction to direct high pressure fluid from the port 356 to the line 374 and the top of the piston 366, while the underside of the cylinder-bearing piston 366 through the line 376 is vented to a low pressure return line 386 via the bore 370 , and the associated conduit 388. The valve 380 is adjustable in an opposite direction to direct pressure fluid from the inlet 356 to the conduit 376 and the underside of the piston 366, while the conduit 374 communicates down the return conduit 386 through a chamber 378 and return line 379.

It should be noted that the piston 366 cooperates with the housing 354, as well as with a circular wall portion 390 projecting from this housing, to prevent fluid communication between the chamber 378 and the cylinder 364.

The spring 382 acts to sense the position of the piston 366 and the guide rail angle, and acts as a feedback device on the valve 380. The relative magnitudes of the compression of the spring 382 in comparison with the springs 383-385 provide a highly amplified reaction which requires great movement. of the piston 366 (for example 14 times) to counteract as an initial movement, return the valve 380, and return the valve to its central position. From this, it will be appreciated that the piston 366 moves in a servo-like follower motion following the movement of an "inlet piston" in the form of the valve 380. line 394 acting on a shoulder 393 of the piston 392. The piston 392 forms an adjustable stop for varying the compressive force of the spring 383. The pressure acting on the shoulder 393 is counteracted by a spring 385. A rod 395 slidably extends through the center of the element 392, and this rod 395 acts as a variable adjustable stop for the spring 384 extending between the upper end of the post. 395 and the valve 380. The rod 395 is displaceable in its longitudinal direction in dependence on pivoting of a lever 396 which is pivotally mounted to the housing 354 by means of the pin 398.

The guide rail actuating actuator or control means 66 further includes another bore 400 in which a control pressure generating throttle control valve 402 is provided. pushes the valve 402 in the downward direction. The spring 406 is counteracted by a gradient compression spring 408 designed as a helical spring. gas control valve 402 via a conduit 412 with a damping opening 414. The conduit 410 leads to the larger surface of a stepped piston 416 which is slidably disposed within another bore 418 in the housing 354. One end of the bore 418 is throttled fluid connection to the return line 387 via an opening 419. The smaller diameter section of the riser 416 receives pressure fluid from the line 420. Through a suitable drain line 424, the intermediate section of the riser, as well as the upper end of the valve 402, is drained to the low pressure return 38 the line 388.

Line 420 provides a hydraulic signal indicating the speed of the power turbine shaft 82. In this connection, it should be noted that the guide rail actuator comprises a non-positive hydraulic displacement pump, such as a centrifugal pump 422, which is mono-; rotated on and rotated by the power turbine shaft 82. By being a non-positive displacement pump, the pump 422 delivers a flow of hydraulic pressure fluid through the conduit 420 so that the pressure maintained on the smaller diameter portion of the piston 416 is a quadratic function of power turbine shaft 82 speed. Similarly, the throttle control valve 402 acts to develop a pressure on the larger diameter portion of the piston 416 relative to a desired or selected speed which is reflected by the setting position of the throttle control 184. The valve 402 and the piston 416 act as input signal means and as a comparator for comparing the compressive force of the spring 384 as a function of the difference or error between the actual power turbine speed and the desired power turbine speed determined by the setting of the throttle. The desired or requested speed Npt is shown graphically in Fig. 19.

The guide rail actuating member 66 further includes a linearly proportional electromagnet actuator 426 which 96 is operatively connected by electrical connection leads 427 to the electronic control module 68. The actuator 426 comprises a housing 428 surrounding a coil 430, and a centrally located armature supporting a hydraulically directional control valve 432. The valve 432 is normally pressurized upwardly by the spring 434 to the position which connects the conduit 394 to the return conduit 386. the valve 432 is proportionally displaceable downwardly depending on the magnitude of the actuation signal to increase proportionally for - the connection between lines 372 and 394 and at the same time reduce the connection between line 394 and the drainage. As a result, the pressure in line 394 increases in proportion to the magnitude of the electronic signal, and this pressure is substantially zero in the absence of an activation signal or drive signal to the electromagnet 426. It should be noted that the minimum pressure in line 394 allows the springs 383 and 385 to exert maximum upward force on the valve 380, and that increasing pressure in the conduit 394 displaces the piston 392 downward to reduce the force exerted by the springs 383, 385 on the valve 380, whereby a compensating or dominant force develops in the form of reduced force from the spring 383.

In the absence of an electrical signal to the electromagnet 426, minimal pressure is applied to the shoulder 393, which means that the guide rails will be regulated by the power turbine speed. At start-up, therefore, the guide rails are in their position shown in Fig. 14, and at others i_______________. wh_a2os7os-o 2. state of engine operation, they are normally adjusted to the maximum power position according to Fig. 15. As shown in Fig. 18, the guide rail adjusting means 66 is operable to change or vary the guide rail angle B from 0 ° to + 20 °, to change the positive angle of gas flow. against the power turbine blades and thereby change the power transmitted from the gas flow for rotation of the power turbine wheels in a direction that transmits driving force to the vehicle. The guide rail adjusting means 66 is also operable to adjust the guide rails to a position of negative angle of incidence, and to modulate the setting of the guide rails within the zone indicated by d in Fig. 18. In these positions with a negative angle of incidence, the gas flow is so directed that it counteracts and thus strives to retard the rotation of the power turbine wheels.

The electronic control 68 A portion of the control logic of the electronic control module 68 is shown in Fig. 17. The electronic control module receives electrical input signals indicating the power turbine speed Npt via a chopper (divider) 436 connected to the power turbine shaft 82, and a suitable magnetic monopoly 438. which transmits an electronic signal indicating the power turbine speed via line 440. Similarly, the gas generator speed N99 is sensed by a chopper 442, a monopoly 444 and lines 446. Converters 448, 450 and 452 generate respective electrical input signals indicating the respective thus sensed temperature, i.e. the compressor inlet temperature T2, the turbine inlet temperature T4 and the turbine outlet temperature TG. As shown, these temperature signals are transmitted via lines 454, 456 and 458. The electronic control module also receives, from an ambient pressure sensor 460 and associated line 462, an electrical signal indicating the ambient pressure P2. The electronic control module further receives from a suitable sensor device (sensor device) an electrical signal via lines 464, which indicates the setting position of the throttle control 184 which is denoted a. A switch 466 is also manually adjustable by the vehicle driver when he wishes power feedback braking (described in detail). below). A converter S44 generates a signal to a phase inverter 546 as soon as the adjustable guide rails have been switched past a predetermined position a *. The electronic control module includes several output signals for activating (current supply) and / or deactivating 2s azosvos-o Ticke current supply) of the various logic electromagnets and relays, including the electromagnet 518 via line S19, the electromagnet 257. via line 268, fuel sequence the electromagnet 350 via the associated line 351, the fuel adjuster electromagnet 239 via the line 250 and the guide rail electromagnet 426 via the line 427. The electronic control module comprises function generators S14, S50 and 552. The block S14 denotes a function with "straight rated value and torque limit" "and generates a signal indicating the maximum allowable gas generator speed as a function of the ambient state variables T2 and P2 and the power turbine speed Npt. The element S50 converts the setting signal a of the throttle control into an electronic gas generator speed demand signal, and the function generator SS2 generates a signal which is a function of the gas generator speed Ngg from the line 446. The module further comprises comparators 497, S34, S40, 554, 556, 556, 556 logic elements 498, 500 and 538. The logic elements are of the type "lowest wins", ie they emit the algebraically lowest input signal. Logic element 498 selects from signals S36 and 542 generated in comparators 584 and 540 and indicates the magnitude of the over- or under-temperature of T1 or T6. An additional quantity from 456 is provided to the logic element 498 to give an indication of too high T1 values in the event of a missing T4 sensor signal. The logic element S00 receives magnitudes from 497 and 498. The comparator 497 compares the electronic speed requirement with the actual gas generator speed 446 to determine if the engine has been ordered to accelerate or operate in a stationary state. The magnitude from the logic element S00 is fed to the phase inverter S46, whereby a suitable signal is generated in the electromagnet drive S58, which then converts the adjusting electromagnet 426 a distance proportional to the magnitude of the signal 427.

The logic element 538 receives its magnitude from the comparators S54 and 556, the logic element 498 and a differentiator S48. As pointed out, the logic element 498 indicates the lower of the two temperature errors T4 and T6. The magnitude from the comparator 556 is the error between the power turbine speed Npt desired by the driver. and the actual power turbine speed Npt. The magnitude of the comparator 554 indicates the difference between the maximum allowable gas generator speed determined by the function generator 514, and the actual gas generator speed 446. The logic element 538; ,, ~ j _., H¿_wlà _... h,., _ ¿V¿, , w, __ fi ,, _ v ,, g Q! Wszosvos-o 2, Selects the lowest algebraic signal and outputs it to the electromagnet driver 560 with a magnitude on the line 250 which is passed on to the controller: the electromagnet 239 included in the fuel control 60 for reduced adjustment. As shown in Fig. 17, the electronic control module comprises a comparator 468 and synthesizers or function generators 470, 472 and 474. The function generator 470 generates an output signal in line 478 which indicates whether the difference between the power turbine speed and the gas generator speed is still less than one. maximum value, such as SS. the function generator 472 generates a signal in the line 480 which shows whether or not the power turbine speed is greater than the gas generator speed, while the function generator 474 generates a signal in the line 482 which shows whether or not the gas generator speed is greater than 45% of the maximum speed. The control logic further comprises the function generators 486 and 488 which respectively generate signals in associated lines 490 and 492, which signals show whether (or not) the input input speed is greater than a predetermined minimum value e, and whether the throttle setting position is less than a predetermined throttle control setting a *. The throttle control setting a is obtained from a suitable position sensor such as a variable resistance potentiometer. The output signal 464 thus gives an indication of the setting position a of the throttle control.

The electronic control module further includes the logic gates 502, SO 4, 506, 508 and 562. The logic AND gate 502 receives interference from line 478 and AND gate 506 to generate an output signal to the electromagnet driver 516 to activate the power feedback. 84. The logic AND gate 506 receives its magnitudes from line 482, current. switch 466 and line 492 and generates an input signal to AND gates 502 and 504. The logic AND gate 504 receives a magnitude from line 480 and the phase inverse magnitude from line 478. Its magnitude generates a 50% gas generator speed signal, and also enables the electromagnet driver S64 through the OR gate 562 to generate the α signal in line 268, which signal is the result of a constant 50% signal plus the magnitude of the element 566. The signal 268 then activates the electromagnet 257 included in the fuel control 60 to increase the regulator setting. The logic AND gate S08 receives its magnitudes from lines 490 and 492. Its output signal generates a 20% gas generator signal through the function generator 568, which signal, added to the constant 50% signal of the summer 570, results in a fast idle signal (70% gas generator speed) to the regulator's reset boost electromagnet 257. The magnitude from AND gate 508 also generates the satisfying signal to electromagnet drive 564.

The power feedback clutch 84 Although different types of clutches could be used as the power feedback 84, for the preferred embodiment shown in Fig. 3, it comprises a "wet" type of hydraulically actuated clutch comprising a shaft 520 from the gear transmission 78 connected to the throttle shaft 76, and a shaft 522 coupled to the gear transmission 80 which communicates with the output shaft 82 of the power turbine. The coupling operates in a continuous bath of lubricating cooling fluid.

The gas generator shaft S20 drives a plurality of discs 524, which are placed alternately between discs 526 which are connected to the output shaft 522. The actuating means of the coupling is in the form of an electromagnetically operated directional hydraulic control valve 518 which, in the activated position shown, conducts pressure fluid, e.g. from the source 362, into a fluid pressure chamber 528 to press the piston. 530 against the action of force from a return spring 532, to force the discs S24, S26 into mutual frictional engagement so that the driving force from the shaft S22 can be returned to the gas generator shaft 520 to contribute to braking. When the electromagnet actuator 518 is deactivated, the chamber 528 is emptied into a low pressure drain to allow the spring 532 to displace the piston S30 away from the position shown and disassemble the discs 524, S26.

OPERATION Start In a conventional manner, the starter motor 72 is activated electrically to initiate the rotation of the drive shaft 76 of the gas generator and the input shaft 152 of the fuel regulator 60. The control module 68 activates the normally open fuel sequence electromagnet 350, and the electromagnet 352 is also in an open position to keep the fuel line 64 open for fuel supply to the combustion chamber. When required, a pneumatic auxiliary pump 74 supplies compressed air to the combustion chamber 98 while bringing spark plugs 100 into operation. The engine 72 is used to drive the various components described until the gas generator section reaches its operating maintenance speed, which is normally in the range of about 40% of the maximum gas generator speed. During the initial rotation and start-up of the engine, the low speed of the fuel regulator drive shaft 152 cannot overcome the bias from the speed increase spring 224, and thus the fuel lever 226 is moved away from and exposes the opening 178 to allow fuel flow from line 146 to outlet thereof. initial start also applies Q that the combustion chamber temperature {T3_S) and the combustion chamber pressure (P3'5) are both relatively low, so that the setting valve 62 also allows considerable fuel flow through the line 64 to the combustion chamber.

Low idle When the speed of the gas generator shaft 76 increases above the operating maintenance speed, the starter motor 72 is switched off and the combustion process enables self-sustaining operation of the gas generator. The speed increase spring 224 is normally set to maintain a low idle value of the order of approximately SCÛÉ of the maximum rated speed of the gas generator. Thus, the mechanical centrifugal weight controller is operative to counteract the spring 224 to adjust the fuel lever 226 and maintain fluid flow through the opening 178 to maintain the gas generator speed at a nominal value of 50% of the maximum value. This 50% low idle speed is effective as soon as the proportional electromagnet 257 is in the deactivated state shown in Fig. 6. The electronic control module 68 normally maintains the electromagnet 257 in the deactivated state to select the low idle speed of the gas generator as soon as the transmission The input shaft speed, i.e. the speed of the shaft 36 sensed by the speed sensor 48, indicates that the shaft is rotating. This normally occurs as soon as the clutch 34 is switched on and the transmission 38 is set to its neutral position, or as soon as the vehicle moves regardless of whether the clutch 34 is switched on or off. Accordingly, at idle when there is no acceleration of the motor, the comparator 486 in the electronic control module 68 notes that the speed of the shaft 36 exceeds a predetermined minimum value e, so that no signal is transmitted from the comparator 486 to the AND gate 508. The electromagnet 257 remains deactivated, and the gas generator speed is regulated by the controller to 29 8205705-0 Approximately 50f of its maximum speed.

High idle Maximum power normally needs to be developed by an engine driving a ground vehicle when starting acceleration of the vehicle from a stationary or substantially stationary starting state.

As a natural consequence of the driver's normal actions when starting from a stationary starting position, the input shaft 36 of the transmission is stopped to rotate or rotate at a very low speed when the clutch 34 is disengaged while the gear lever 46 is operated to engage a gear in the transmission. As soon as the speed of the shaft 36 falls below a predetermined speed value e, the comparator 486 of the electronic control module generates an output signal to the AND gate S08. Since the throttle lever 184 is still in its idle position, the sensor connected to the line 464 generates a signal to activate the comparator 488 and also send a positive signal to the AND gate S08. The magnification from AND gate 508 activates function generator 568 to add 20% to the constant idle instruction of 50% so that summer 570 provides a 70% instruction signal to electromagnet driver 564 actuated by the magnification from AND gate 508 and OR. gate 562. The electromagnet 257 is thus activated by a suitable current signal through line 268 to be switched to its position shown in Fig. 6C. In this position, the electromagnet 257 has been activated sufficiently to drive the shaft 262 and the plunger shaft 272 downward as shown in Fig. 6C, and exert a force on the fuel lever 226 which tends to pivot the latter away from and increase the size of the opening 178.

The extra force exerted by the electromagnet 257 is sufficient to increase the flow of fuel through the opening 178 and thereby increase the gas generator speed to a predetermined higher level, such as 70% of the maximum speed of the gas generator. The centrifugal weight controller works to keep the gas generator speed constant at this level.

In this way, the idle speed of the gas generator section is reset to a higher value while waiting for the required acceleration, so that more power will be instantly available for acceleration of the vehicle. When acceleration is not to be expected, which is determined by whether the input shaft 36 of the transmission rotates or is stationary, at the same time the electronic control module 68 is operative to deactivate the electromagnet 257 and reduce the gas generator speed to an idle O -S. Y <Imwßww fifl. öïiazosvos-o ° 30 value just above what is required to maintain self-sustaining operation of the gas generator section. In this way, the power required for acceleration will be available when needed; while, on the other hand, during other idle operation, the engine's fuel flow and thus fuel consumption is maintained at a significantly lower value. This is achieved by generating a signal corresponding to the minimum speed of the shaft 36, which signal anticipates a later signal (oscillation of the throttle lever 184) which requires a considerable increase in the power transmitted to drive the vehicle.

Acceleration - Acceleration of the gas turbine engine is accomplished manually by depressing the throttle control 184. For the fuel regulator 60, this depressing generates a throttle section-error signal by depressing the lever 184 to rotate the shaft 192 to increase the compression of the spring 22 mechanical centrifugal weight sensor. The fuel lever 226 pivots in a direction that substantially exposes the opening 178 for increased fuel flow to the combustion chamber.

At the same time, depressing the throttle lever 184 produces a power turbine section speed error signal to the guide frame actuating actuator 66. More specifically, depressing the throttle 184 causes the spring 406 to compress the valve 402 downward and increase the pressure in the cam. substantially above the pressure generated by the hydraulic speed signal generator for pressure developed by the pump 422 and applied to the other side of the piston 416.

Accordingly, the lever 396 pivots clockwise about its bearing pin 398 in Fig. 12 and allows downward retraction, if required, of the plunger rod 395 and reduction of the compression of the spring 384.

The summer 497 in the electronic control module determines a large difference between the throttle position and the gas generator speed to develop an electronic signal to the element 500 which overcomes other signals to this element and reduces the signal in the line 427 to zero to deactivate the electromagnet 426 in the guide rail control 66. The spring bias pressure pushes the plunger 430 and the valve 432 to the position shown in Fig. 12 to minimize the hydraulic pressure which develops in the line 394 and which is exerted on the piston shoulder 393. As already discussed in the case of zrzosvos. above in connection with the writing of the guide actuating actuator 66, the springs 382-385 adjust the valve 380 to effect the following movement of the piston 366 to its nominal or "neutral" setting position. In this position of the guide piston 366 and the rod 368, the guide rails 120 are set in the position shown in Fig. 14, the gas flow from the combustion chamber being directed towards the power turbine guide rails in a manner which minimizes the power transmitted to the power turbine guide rails. More specifically, the guide rails 120 are set in their position shown in Fig. 14 to reduce the pressure drop or pressure ratio across the turbine vanes 117 to a minimum value, and this setting position corresponds to the position indicated in Fig. 18.

Since the nozzles 104 maintain the combustion chamber 98 in a throttled state, this decrease in the pressure ratio across the turbine blades 117 produces a significant increase in the pressure ratio across the radially inflow turbine 102 in the gas generator section. Adjusting the guide rails in their setting position shown in Fig. 14 by allowing the springs 382-385 to position the valve 380 and, the piston 366 in its "neutral" position, consequently changes the power distribution between the gas generator turbine 102 and the power turbines 116, 118, so that a predetermined maximum part of the power from the flow of flowing gas is transmitted to the gas generator turbine 102. As a result, maximum acceleration of the gas generator section is achieved from either its low or high idle setting in the direction of its maximum speed.

As pointed out earlier, the requirement for imminent acceleration has been sensed, and the engine is normally already at its high idle setting so that the gas generator speed quickly approaches its maximum value. Consequently, as the gas generator speed increases, the combustion chamber pressure P3_5 also increases. This causes rotation of the metering or control valve 282 in the fuel setting control 62 to increase the size of the overlap between the acceleration setting window 284 and the opening 298 in the fuel setting valve. Increasing this opening results in a concomitant increase in the fuel flow to the fuel chamber 98 and a final resulting increase in the inlet temperature T3_5 by the action of the recuperator 56.

For the operation of the engine 30, an increase of T3_5 has in practice the same effect as a further increased fuel flow. By solving the above equation in szosvos-o 32 å in Gen, the window 284 is thus shifted to decrease the fuel flow with increasing T3_5 to provide an "efficient" fuel flow, i.e. a flow which combines the effects of actual fuel flow and the inlet temperature T3_5 the sensed overpressure P3_5 to generate a desired combustion chamber outlet temperature or gas generator turbine inlet temperature T. This increase in fuel flow caused by the rotation of the valve 282 and compensated by axial translational movement of the valve provides an "efficient" fuel flow that increases the power generated and transmitted from the gas flow to the gas generator turbine 102. This causes then another increase in the gas generator speed, and the combustion chamber pressure P3_5 increases again. The setting valve thus functions in a regenerative manner by further accelerating the gas generator section. As previously pointed out, the setting valve is so preformed that it satisfies the equation discussed above, and allows further increase of_P3_5 while maintaining the combustion chamber outlet temperature T4 at a relatively constant, high value. In this way, the gas generator section is accelerated very quickly and with maximum efficiency because the turbine inlet temperature T4 is maintained at a high, constant value.

Although the acceleration window 284 and the opening 290 may be mutually arranged and designed to maintain a constant value of T4 throughout the acceleration, a preferred embodiment is intended to maintain a substantially constant value T¿ as soon as the power turbine has started to rotate, while the turbine outlet temperature or the inlet temperature of the recuperator is limited during a first part of the acceleration. In this way, excessive values of T6 are avoided when the power turbine section has stopped or has almost stopped. More specifically, it should be noted that during initial acceleration of the vehicle, the free power turbine section 54 and its shaft 82 are stationary or they rotate at a very low speed due to the mass inertia of the vehicle. Thus, only a small temperature drop occurs in the gas flow as it flows through the power turbine section, and the recuperator inlet temperature T6 begins to approach the temperature of the gas flow leaving the gas generator radial turbine 102. If the combustion chamber outlet temperature or gas generator turbine 'aim-IM vffw' h; _- a: 8205705-0 At this time, it is possible that the T6 may become too high in the event of a high inertia load which prolongs the time of this substantially "stopped" state of the power turbine section. When the power turbine section overcomes the inertia and reaches higher speeds, the temperature drop across the power turbines naturally increases and keeps the recuperator inlet temperature T6 down.

For such free turbine engines, one can normally count on relatively complicated and expensive control devices, electronic and / or mechanical, in order to be able to avoid excessive values of T6 and at the same time achieve a reasonably fast acceleration under the condition in question. A significant advance in the present invention, concretized by the adjusting valve 62, is the provision of an extremely simple, economical, mechanical construction capable of limiting T6 during the critical standstill period of the turbine section, but still promoting a very fast responsive engine acceleration. execution eliminated the need for compensation for significant variations in ambient pressure, and thus the need to compensate for such variations in altitude that can be expected to be relevant for the ground vehicles in question.

In this context, it can be expected that the absolute combustion footprint P3_5 must be the parameter when solving the equation described above, so that the setting valve on a supply. can reliably "calculate" the turbine inlet temperature T4 which arises by a special combination of the combustion chamber pressure P3_5- and the inlet temperature T3_5.

An insight according to the present invention is, however, that by correctly selecting the constants K1, Kà, as these are concretized in the size and design of the openings 284, 290, and by using the overpressure of the combustion chamber instead of the absolute pressure of the combustion chamber, a mechanically simple and economical design with minimal control complexity achieve the desired control of both T6 and T¿ during acceleration. The window 284 and the opening 290 are so arranged that when the valve 282 is rotated to a minimum value P3_5, a certain smaller overlap remains between the window and the opening. A minimum fuel flow Wf is thus maintained at this state which is a function of T3_5 since the valve 282 can still undergo axial translational movement. This gives rise to the third term K3T3_5 in the equation given above, and dictates an initial state 8205705-0 34 Dry the fuel flow when the window 284 becomes the regulating fuel flow parameter at start acceleration.

The constants K1, K2, the actual values of which are determined by the aerodynamic and thermodynamic properties of the engine, are selected so that at a predetermined value P3_5u located between its maximum and minimum values, the acceleration window regulates the fuel flow to maintain a constant value of T4 . at combustion chamber pressure below this preselected value, the acceleration window provides a fuel flow that allows T4 to decrease below its predetermined maximum desired level. It has been found that an inherent function in the use of combustion chamber overpressure rather than absolute pressure in combination with these selected values of K1, K2 and a preselected minimum value of the fuel flow at minimum P3¿5, as determined by K3, is that the fuel flow is regulated by the acceleration window to prevent the P + * recuperator inlet temperature T6 exceeds a preselected value. This approach still uses the simple QGO metrics of windows 284 and 290, both of which are rectangles, to mechanically "calculate" the product of T3_S and P3_5. It follows that at pressures lower than P3_5u, which are characteristic of conditions under which the "standstill" of the turbine section occurs, the use of the combustion chamber overpressure prevents the emergence of potentially harmful excessive values of T6. The point of construction of the window 284 is, of course, the state of maximum vehicle inertia acting on the turbine shaft 82, with lower values of said inertia of course allowing a faster increase of the turbine shaft speed and a shorter time in the "standstill state" described above.

Considering the equation solved by the valve 282, it becomes apparent that the fuel flow Wf is a linear function of P3_5, as shown in Fig. 20, the slope being determined by K1 and X2, and a cutting line being determined by K3, passing through that point. which generates the turbine's preselected inlet temperature T¿ at the selected intermediate value P3_5u. A set of such straight linear curves for Wf as a function of P3_5 will of course be the result of different values of T3_5. Although, if desired, curve fitting of the window 284 and the opening 290 could be used to maintain T4 at exactly the same value at pressures at and above the preselected intermediate pressure P3_5x, in the preferred embodiment it was not used. some together-_ lf »g ~ q -.- \ _ qv. ~.-_ q. 35 in azosvos-ó ßatt curve shape for the window and the opening. Instead, the window and the opening have a rectangular shape, whereby T¿ is allowed to increase very rapidly at combustion chamber pressure exceeding P3 su. However, it has been found that such an arrangement offers an extremely practical approximation to the theoretically desired, exactly constant value of T4, which in practice results in maintaining a substantially constant value T4 at the desired maximum value as soon as the combustion chamber overpressure exceeds the preselected level P3_5x. Accordingly, a distinguishing feature of the present invention is that it limits the recuperator temperature TG to solve the problem of recuperator overheating at start-up for acceleration of a load with high inertia, and still maintains a maximum value of T4 for high engine efficiency during the entire continued acceleration as soon as the inertia has been substantially overcome and for most of the time during the acceleration. At the same time, and contrary to what one would normally expect, it has been found that the need for height compensation is eliminated because there is a certain minimum fuel flow at minimum combustion chamber pressure, which minimum fuel flow varies linearly with the combustion chamber inlet temperature T3_s. The present invention thus offers a simple mechanical solution to the interdependent and complex problems of limiting the two different temperatures T4, T6 for different reasons, dwrs avoiding recuperator overheating but at the same time allowing high engine efficiency and thus a very fast acceleration.

As the gas generator continues to accelerate, the centrifugal weight regulator 208 of the fuel regulator 60 begins to exert greater downward force to counteract the biasing force from the acceleration spring 224. Consequently, the fuel lever 226 begins to pivot in a counterclockwise direction as shown in Fig. 6, to begin regulating or dosing fuel flow. as soon as the opening 178 becomes smaller than that allowed by the metering window 284 in the setting valve 62, the effect of the setting valve is overcome and the fuel regulator 60 begins to regulate the fuel flow to the combustion chamber in a manner which adjusts the gas generator speed to match the selected speed by the rotation of the shaft 192 which is connected to the acceleration lever 184 in the fuel regulator 60.

Similarly, this increase in gas generator speed is sensed in the electronic control module 68 by the summerer 497 so that as soon as the gas generator speed N99 approaches If a speed selected by the position of the accelerator pedal as it is electronically sensed by the line 464, the offsetting (overcoming) signal generated by the summerer 497 is turned off.

In response, the element 500 is allowed to generate a signal that activates the proportional electromagnet 426 of the guide rail control 66. the valve 432 connected to the electromagnet 426 is displaced to increase the pressure exerted on the piston shoulder 393, to allow the piston 366 and the guide rails to be switched from the setting shown in Fig. 14 in the direction of the setting shown in Fig. 15. This conversion of the guide rails from the position shown in Fig. 14 to the position according to Fig. 15 again changes the power distribution between the gas generator turbine 102 and the power output turbines 116, 118, so that greater power is developed over the output turbines and transmitted to the output shaft 82. while a smaller part of the power is transferred to the turbine 102. From this it is understood that the acceleration of the engine and the vehicle takes place first by a change of the propulsion power distribution so that maximum power is developed over the gas generator turbine 102, after which the fuel flow increases according to a predetermined scheme for aq on regenerative way to further increase the power developed over the gas generator, while maintaining the combustion chamber outlet temperature T4 at a substantially constant maximum value. So. as soon as any significant acceleration of the gas generator section has taken place, the guide rails are pivoted to change the power or thrust distribution, so that a greater pressure ratio develops over and more power is transmitted to the power turbines 116,118 and the power output shaft 82.

Cruising speed During normal cruising speed (dwrs when driving at a relatively constant speed or power output level), the guide rail control 66 is effective in primarily changing the work distribution between the gas generator turbine 102 and the power output turbines 116 118 to maintain a substantially constant combustion chamber temperature T¿. This is achieved by means of the electronic control module which comprises a summer 534 which develops an output signal in the line S36 to the logic block 498, which signal indicates the difference between the actual and desired turbine inlet temperature T4. More specifically, the electromagnet 426, so- '.3a @ aa; @ g% ¿aar%? F * ö7% W ““ ”* W' ':'" 33 azosvos-o -š as previously discussed, nibenånes normally activated for generating maximum pressure on the piston shaft 393 of the guide adjusting means, for example, assuming that T¿ exceeds its preselected desired value, a signal is generated to the line S36 and the element 498 to reduce the magnitude of the electrical signal through the line 427 to the electromagnet 426. Accordingly, the spring bias of the electromagnet 434 begins to push the valve 432 in a direction which decreases the fluid connection between the conduits 372 and 394 while correspondingly increasing the connection between the conduit 394 and the outlet conduit 386. The decrease in pressure applied to the piston 393 consequently allows the spring 385 to increase 383 'spring bias to effect upward movement of the valve 380 and corresponding downward movement of the piston 366 to drive the guide rails backward from their settings shown in Fig. 13. 1 (setting position + 20 ° according to Fig. 18) in the direction of a wider position which increases the area ratio and reduces the pressure ratio over the guide rails of the turbines 116, 118. In response to T4 overtemperature, the guide rails are thus opened slightly to reduce the pressure ratio across the turbines 116.118. In response, the increased pressure ratio across the gas generator turbine 102. causes an increase in the gas generator speed. This increase in gas generator speed is then sensed by the centrifugal weight controller 208 in the fuel controller 60 to effect counterclockwise rotation of the fuel lever 226 and reduce the fuel flow through the opening 178.

Consequently, the reduction of the amount of fuel to the combustion chamber 98 reduces the outlet temperature of the combustion chamber or the inlet temperature T4 of the turbine in the direction of its preselected value. The guide rail control thus operates so that it adjusts the setting of the guide rails to the extent necessary, and provides a subsequent adjustment of the fuel flow by means of the fuel regulator 60 due to change of the gas generator speed Ngg to maintain the combustion chamber outlet temperature T4 at the preselected maximum . It should also be apparent from the foregoing that reducing the turbine inlet temperature T4 to a value lower than the preselected desired value results in a corresponding movement of the guide rails 120, 122, in order to increase the pressure ratio across the power turbines 116, 118. This consequently a reduction in the pressure ratio across the gas generator turbine 102, so that the gas generator speed is reduced. In response, the fuel regulator adjusts the fuel lever 226 clockwise as shown in Fig. 6, qui 8265705-0 aa Drive to increase the fuel flow to the combustion chamber and thereby increase the turbine inlet temperature T4 back to the desired value. It is obvious that the changed setting of the guide rails also directly changes the outlet temperature T4 of the combustion chamber depending on the difference in air flow therefrom; however, most of the change in the combustion chamber outlet temperature is accomplished by changing the fuel flow to the combustion chamber, as described above.

It should now be apparent that during cruising operation, the fuel regulator 60 acts to adjust the fuel flow in such a way that a gas generator speed is maintained in relation to the setting of the throttle lever 184. The fuel regulator 60 apparently operates in conjunction with or is independent of the guide rail control. only dependent on the gas generator contract Ngg.

While the electronic control module controls the guidewheel control electromagnet 426 to adjust the turbine inlet temperature T4 during cruising speed, the hydromechanical portion of the guide rail control 66 is operative in a more direct feedback loop to adjust the speed of the power turbine output shaft. , as sensed by the pressure developed in line 420, is continuously compared to the position of the throttle control arm as reflected by the pressure developed in line 410. A graphical representation of the action of valve 402 and piston 416 in compressing the spring 384 and requesting other desired power turbine speeds Nit in relation to the throttle position a, is shown in Fig. 19. In response to an increase in the speed of the power turbine shaft 82 to a value exceeding the island selected by the pivot of the throttle lever 184, the pressure at the smaller diameter piston 416 was significantly greater than the pressure on it the larger surface of the piston 416 to pivot the lever 396 so as to increase the compression of the biasing spring 384 acting on the valve 380. The resulting upward movement of the valve 380 causes a corresponding downward movement of the piston 366, and consequently causes adjustment of the guide rails in the direction of the position shown in Fig. 14, dxrs provides an opening of the guide rails to increase the area ratio and reduce the pressure ratio across the vanes of the two power turbine wheels 117, 119. This reduces the power transmitted from the gas flow to the power turbine wheel, and thus provides a small decrease in the speed of the output shaft of the power turbine back to the value selected by means of the throttle control 184. It is recognized that as soon as the speed of the power turbine shaft 82 is lower than the speed selected by the throttle control arm 184, the compression is reduced. of the spring 384 in an effort to increase the pressure ratio across the power turbine blades 117, 1 19 to thereby seek to increase the power turbine speed Npt The part of the guide rail control 66 which is intended for adjusting the power turbine speed in relation to the position of the throttle control is preferably primarily digital in its action, since as shown in Fig. 19 a small change in the setting position of the throttle control arm increases the required speed Npt from 25% to 100%. This action of the valve 402, the piston 416 and the plunger piston 395 is such that when the throttle is in a position greater than a *, said part of the control continuously requests approximately 105% power turbine speed Npt. By a smaller degree of oscillation of the throttle control to a position less than a “, the control produces a request for a power turbine speed which is proportional to the setting position of the throttle control. Adjusting the throttle at an angle smaller than said small arc causes the control to request only about 25% of the maximum value of Npt. when driving at normal cruising speed, the counting means or regulation of the guide rails is thus effective in cooperation with the fuel regulator in order to maintain a substantially constant turbine outlet temperature T4; the fuel regulator 60 operates to adjust the gas generator speed Ngg to a value selected by the throttle control arm 184; and the hydromechanical part of the guide rail control ba: operates so that it adjusts the output speed Npt of the power turbine to a level in relation to the setting position of the accelerator pedal 184.

It will further be appreciated that during operation in this cruising condition the opening generated at the opening 178 in the fuel regulator is substantially smaller than the openings for the fuel flow provided in the setting valve 62, so the setting valve 62 does not normally interfere with the control of the engine at this stage.

Safety tools_§ that take overhangs During cruising or other operating conditions for the engine discussed here, several safety functions that, if necessary, take over continuously are connected. For example, the electromagnet 239 in the fuel regulator 60 is operative to substantially reduce or counteract the effect of the acceleration spring 224 and provide a concomitant reduction in fuel flow from the orifice 178 by exerting on the fuel lever 226 a force which is swing the latter arm in the counterclockwise direction seen in Fig. 6.

As shown in Fig. 17, the electronic control module comprises a logic element S38 responsive to the power turbine speed Npt, the gas generator speed Ngg, the turbine inlet temperature T4, and the turbine outlet temperature or the recuperator inlet temperature TG.

Accordingly, if the turbine inlet temperature T¿ exceeds the preselected maximum value, a proportional electrical signal is transmitted to the lines 250 to activate the electromagnet 239 and reduce the fuel flow to the engine. Similarly, excessive turbine outlet temperature T6 results in proportional drive or activation of the electromagnet 239 to reduce the flow of fuel to the combustion chamber and thereby ultimately reduce the turbine outlet temperature T6. The logic element 438 also responds to the power turbine speed to proportionally activate or drive the electromagnet 239 as soon as the power turbine speed exceeds a preselected maximum value. Similarly, the electronic control module is operative to activate or energize the electromagnet 239 as soon as the gas generator speed exceeds a preselected maximum determined by the function generator 514 as a function of P2, T2 and Npt. Normally, the preselected maximum parameter values discussed with respect to these safety drives: which, if necessary, take precedence, are slightly above the normal operating values of the parameters, so the electromagnet 239 is normally inactive except in the event that one of these parameters significantly exceeds its desired value. For example, during operation in a cruising state or when the car rolls without being driven by the engine, when the vehicle is driven in a downhill slope and at least to some extent propelled by its own weight or inertia, the electromagnet 239 is effective in by increasing the speed of the output shaft 82 of the power turbine in addition to the desired value, to bring about a reduction of the fuel flow to the combustion chamber in order thereby to strive to regulate the output speed of the power turbine.

Although the guide rail control, as previously discussed with respect to the cruising speed of the vehicle, is normally sensitive to the combustion chamber outlet temperature T4, as reflected by the signal generator through the element 435, the logic element 498 also reacts to the turbine outlet temperature T6 compared to a maximum of this temperature, as said comparison, takes place by means of the summer 540 which generates a signal through the conductor 542 to the element 498 as soon as the turbine outlet temperature T6 exceeds the preselected maximum value. The logic element 498 responds to a signal from either line 542 or S36 by reducing the magnitude of the electronic signal supplied through line 427 to electromagnet 426, thereby reducing the pressure ratio across turbine wheels 116, 118. As previously discussed, this change in pressure ratio to increase the gas generator speed and, depending on the fuel regulator 60, reduce the fuel flow to the combustion chamber so that the turbine outlet temperature TG is prevented from increasing beyond a predetermined maximum limit value.

If desired, the electromagnet 239 can be activated in response to other parameters that prevail from a safety point of view. For example, to protect the recuperator 56 from excessive thermal stresses, the logic element 538 may include a differentiator 548 which communicates with the signal from the turbine outlet temperature T6, to generate a signal indicating the rate of change of the turbine outlet temperature Te. Logic element 538 can thus generate a signal which activates the electromagnet 239 as soon as the rate of change of the turbine outlet temperature ïk exceeds a predetermined target value. In this way, the electromagnet 239 can regulate the maximum rate of change of the temperature in the recuperator, and thus the thermal stress to which the recuperator is subjected. Similarly, the logic element 53% 'can act to limit the maximum power developed over the power turbine and / or gas generator shafts.

Gearbox Since the turbine engine 30 is of the free turbine type and thus has a power output shaft 82 which is not physically connected to the gas generator shaft 76, the power turbine shaft 82 would normally strive to very significantly increase its speed during a gear (gear change) at which, after disengaging the drive clutch 34 to enable shift in the gearbox 38, virtually all inertia loads are disconnected from the power turbine shaft 82 and the associated power shaft 32. In normal manual shift change, of course, the throttle control arm 184 is released so that the fuel regulator 60 immediately begins to significantly reduce the fuel flow. 98. Due to the high moment of inertia of the power turbine shaft 82 as well as the large volumetric gas flow over the power turbine from the combustion chamber, the power turbine shaft would still tend to rotate at too high a speed.

'J'. ; .g, wh @ ~ §; g5i5, m "'- fg. + .fn-w." šåosvos-o 42 F The control system referred to in the present invention consequently uses the guide maneuvering control 66 to adjust the guide rails. 120, 122 against their "reversed" position shown in Fig. 16, so that the gas flow from the engine's the vanes of the power turbine wheels 117, 119 in the opposite direction in such a way that the rotation of these power turbine wheels is counteracted. The gas flow from the engine is thus used to decelerate instead of drive the turbine shaft 82. As a result, the power turbine shaft tends to reduce its speed to the point where synchronous shifting of the gearbox 38 and subsequent reconnection of the drive clutch 34 can be performed easily. and quickly without damaging the engine or drive transmission.

More specifically, the hydromechanical portion of the guide rail control 66 is arranged so that when the throttle lever 184 is released, as is the case when shifting, a very large error signal is generated by the high pressure from the power turbine speed control line 420 to pivot the lever 39 in the counterclockwise direction to cause a considerable increase in the compression of the spring 384 / A sufficient compression of the spring 384 results in the valve 380 being pushed upwards and the drive piston 366 downwards to its position shown in Fig. IQ. The position setting of the piston 366 corresponds to the position setting of the guide rails 120, 122 in the setting position shown in Fig. 16. The gas flow from the combustion chamber is then directed by the guide rails over the turbine wheel vanes 117, 118 in the opposite direction to their direction of rotation to decelerate the power turbine shaft 82. Since the drive clutch 34 is disengaged during this shift operation, the power turbine shaft 82 retards fairly quickly due to the opposite gas. by adjusting the guide rails 120 in their position shown in Fig. 16. Even more particularly, the arrangement of the springs 406, 408 and the relative magnitude of the pressure developed in the conduits 410 and 420 cause the hydroecanic portion of the guide maneuvering control 66 to act in the manner described above to effect adjustment of the guide rail. 120 to their negative or reversed setting direction shown in Fig. 16, and modulate the setting of the guide rails within the zone designated in Fig. 18 by d in relation to the magnitude of an excessive value for Npt, as soon as the throttle control arm 184 moves to a position smaller than a default setting position au for the throttle control arm. As the speed of the power turbine shaft 82 is reduced, the piston 416 begins to displace in an opposite direction. l 'w nxßf-g 4, ö azosvos-om'ing to reduce the compression of the spring 384 as soon as the turbine speed has been reduced to a preselected value. The action of the piston 416 in the preferred embodiment is such that the piston has the ability to modulate the degree of compression of the spring 384 in relation to the magnitude of the Npt error. The larger the speed error, the more the guide rails are swung to a "harder" braking setting position. The position adjustment of the guide rails is thus maintained in a reversed braking state and is modulated within the zone d near the maximum braking position -95 ° shown in Fig. 18 in relation to the speed error of the power turbine. As soon as the gear-changing gearbox has been completed, the control system is of course effective, through the previously discussed acceleration operation, in increasing the power turbine speed again.

Deceleration A first state of deceleration of the gas turbine engine. is achieved by reducing the fuel flow according to the deceleration scheme available through the deceleration window 286 in the setting valve 62. More specifically, the release of the throttle control arm 184 causes the fuel regulator 60 to very significantly restrict the fuel flow through the opening 178. As a consequence, the fuel flow is minimal. the gas turbine engine through the deceleration fuel line 142 and the associated deceleration window 286 in the setting valve. As previously noted, the deceleration window 286 is specifically designed for the gas turbine engine to continuously reduce fuel flow according to a scheme that maintains combustion in the combustion chamber 98, i.e. substantially along the operating line of the gas turbine engine to maintain combustion, but below the line corresponding to " . Even without pivoting the throttle control arm 184, the electromagnet 239 can, as previously pointed out, be activated on special occasions to generate a spurious throttle control level signal to the fuel lever 226 to effect deceleration by strictly limiting fuel flow.

This deceleration by limiting the fuel flow is achieved by reducing the throttle level to a position at or immediately above a preselected position a * for the throttle setting. This throttle setting position is normally just slightly above the minimum throttle position, and generally corresponds to the position of the throttle lever during the rolling condition where the engine is driven to some extent by the inertia of the vehicle, such as when the vehicle is rolling downhill. Since this deceleration by throttling the fuel flow acts only through the regulator 60, it is obvious that the guide rail control is unaffected by it and continues to be effective in the conditions previously discussed. This is especially true since the throttle control has been lowered to, but not lowered below, the preselected throttle control position a * to which the hydromechanical portion of the hinge adjusting member 66 is sensitive. when the throttle control arm 184 continues to pivot down below the axle position and towards its minimum position, a second state of deceleration or braking of the vehicle arises. In this state, the movement of the throttle control arm down during the position a * causes the hydromechanical part of the guide rail adjusting member 66 to produce a considerably larger error signal with respect to the power turbine speed to pivot the guide rails 120 to their reversed position or "brake position" shown in Fig. 16. More specifically, as discussed above with respect to the shift of the vehicle, this large error signal for the power turbine speed in comparison with the position of the throttle control arm causes significant counterclockwise oscillation of the lever 396 and a consequent compression of the spring 384. through the piston 366 and the guide rails are driven in the direction of their position shown in Fig. 16. As a result, the gas flow from the gas turbine engine counteracts the rotation of the turbine wheels 116, 118, and causes a considerable tendency to decelerate the output shaft 82. It has been found that for a gas turbine engine in the power class 450-600 hp, this causes reversal or reversal of the guide rails in combination. with minimal fuel flow to a burning braking effect of 200 hp or more on the turbine's output shaft 82.

It should be noted that during this second state of deceleration, as well as during the shift operation discussed earlier, and since the guide rails are now set in their "reversed" or reversed position, the logic provided by the electronic control module 68 , in terms of controlling the electromagnet 426 to prevent overtemperature of T¿ or TG, now operating in the opposite direction to that required.Therefore, the electronic control logic also includes a converter 544 which senses the change as soon as the guide rails pass. over the center position indicated in Fig. 18 by the predetermined chamber, as this flow is determined by the deceleration window 286, ß, u äífïw. a »,«,: fw '' .S azósåos-od 'angle B *, and then is in This signal generated by the converter S44 activates a reversing device, such as an inverter S46, which converts the signal to the electromagnet 426. More specifically If, during this deceleration operation with the guide rails in the position shown in Fig. 16 with a negative setting angle, an excessively high combustion chamber outlet temperature T4 or too high turbine outlet temperature T6 would arise, then the signal generated by the element 500, in order to reduce the magnitude on the current signal, is reversed by the element 546. The occurrence of a high value of T4 or T6, when the element S46 is activated, consequently generates an electrical signal with increasing strength to the electromagnet 426. In response, the electromagnet 426 drives the valve 432 in one direction which increases the pressure in the line 394 and on the shoulder 393. This reduces the magnitude of the bias of the spring 383 and causes the valve 380 to move downwards. In a subsequent moment, the piston 366 moves upwards to reduce the compression of the spring 382. It follows that the guide rails 120 are adjusted in the opposite direction: from the position shown in Fig. 16 for maximum braking, and back towards the in Fig. 14 showed the neutral position. This movement, of course, reduces the magnitude of the power transmitted from the gas flow in counteracting the rotation of the guide rails 117 to effect a consequent reduction in the fuel flow, as previously discussed. The reduced fuel flow _ then reduces the size of the overtemperature parameter T4 or TG. .

Such an effect for regulating T¿ or TG will mainly only take place when the fuel flow supplied to the combustion chamber is greater than that permitted by the deceleration setting 286.

Thus, such an effect is more likely to occur during "unrolled rolling" than during hard braking during the second deceleration state. This is natural with the operation of the engine, but during hard deceleration the fuel flow to the combustion chamber is minimal and the combustion chamber outlet temperature is relatively low. Under normal conditions, and even with the guide rails in a position with a negative setting angle, it applies, however, that the electronic control module is still effective in returning the guide rails in the direction of their neutral position to try to reduce any overtemperature conditions.

Power recoil braking A third deceleration condition of the vehicle can be selected; w “, ',.,.» \ 4 «.,: _. W 1: unilï'«. u. mh., "a2os7os-of .6 ßå manual route by the driver. This will also normally happen when the vehicle, after initiation of the first two deceleration states described above, is still driven by its own inertia at too high a speed, dwrs when the power turbine shaft 82 Npt is still too high The power turbine shaft Npt may be in a range of approximately 90% of its maximum speed, while the gas generator speed N has been reduced to or to a value close to its low idle speed of approximately 50% of the maximum gas generator speed.

This third deceleration state, called power feedback braking, is manually selected by turning on the power feedback switch 466. In response, the electronic control module 68 generates signals that ultimately result in mechanical interconnection of the gas generator shaft with the power turbine shaft so that the gas generator shaft on the vehicle's drive transmission to provide additional braking effect thereon. More specifically, when the switch 466 is turned on (closed), the AND gate S06 generates a signal to the AND gate 504 because the throttle level is below a preselected point a *, thereby causing the function generator 488_ to generate a signal to the AND gate S06 and since the gas generator is operated at a speed exceeding 45% of its nominal value determined by the element 474. The element 472 develops a signal through the line 480 to the AND gate 504 because the power turbine speed is greater than the gas generator speed in this operating state. The element 470 also notes that the effective relative speeds of the gas generator shaft and the power turbine shaft are outside a predetermined limit, such as pl s or minus 5% noted at the comparator 470. The element 470 consequently does not generate any signal to the AND gates SO 2, 504. More specifically, the element 470 does not necessarily compare the actual relative speeds of the shafts of the gas generator and the power turbine. The element is instead arranged so that it only generates a signal to the AND gates SO2, 504 as soon as the relative speeds of the shafts 520, 522 in the power feedback circuit 84 are within the preselected predetermined limits for each other. The comparator 468 will thus compensate, if necessary, for differences in the current speeds of the gas generator and power turbine shafts, as well as for differences between the gear ratios of the two drive transmissions 78 and 80, respectively, connected to the u two shafts 502, 522 of the feedback coupling 84.

Due to the difference between Npt and N99, no signal is transmitted from element 470 to either AND gate 502 or 504.

As schematically indicated by the circle connected to the input value from the element 470 to the AND gate SO4, this input value is inverted and the AND gate is now operative to generate an output signal since no signal comes from the element 470, and since signals are received from the AND gate gate 507 and element 472. The output signal from AND gate 504 fulfills two functions. First, a 50% N magnitude signal is generated in the function generator 566 and added to the constant 50% bias signal of the summer 570. The resulting signal corresponds to a 100% Ngg speed command. Second, the magnitude from the AND gate S04 passes through the OR gate S62 to generate a signal to the electromagnet 257. This signal is sufficiently large to convert the electromagnet 257 to its position shown in Fig. 6D which exposes the opening 178 of one of the - noticeable fuel flow to the combustion chamber. It will be appreciated that full activation of the electromagnet 257 to its position shown in Fig. 6D essentially implies a false throttle lever signal to the fuel lever 226, thereby causing the lever 226 to pivot to a position normally provided by depressing the throttle lever 184 to its maximum fuel flow mode. Second, the signal from the summer 570 is also a magnitude to the element 497, so that an artificial full throttle signal is generated which takes over the activation signal which maintains the guide rails in their braking position shown in Fig. 16 during the previously discussed second deceleration state. The activation or current supply of the guide rail electromagnet 426 causes an increase in the pressure in the line 394, whereby the springs 382-38S are allowed to adjust the piston 366 and the associated guide rails in the direction of their "neutral" setting position shown in Fig. 14.

Accordingly, it is recognized that the signal from the AND gate 504 generates an acceleration signal to the engine, which signal sets the guide rails 120, 122 in their neutral position so that maximum pressure ratio develops across the gas generator turbine 102, and at the same time the burn chamber is increased. 'considerably. In response, the gas generator section begins to rapidly increase the speed to a value such that the speed of the shaft 522 of the feedback coupling approaches the speed of its, VV., =, «, ¿~. ;, u '8å2 "05705-.0 48 change axis 520.

As soon as the speeds of the power turbine shaft and the gas generator shaft are suitably adjusted one after the other so that the two shafts 520, S22 in the feedback coupling have speeds within the preselected limits determined by the element 470 in the electronic control module, the electronic control module develops a positive signal to both AND gates SO 2, SO 4. This positive signal immediately stops the output signal from AND gate SO4 to deactivate the proportional electromagnet 257 in the fuel regulator and again reduce the fuel flow back to a minimum value, and at the same time stops the overriding signal to the element SO0 so that the guide rails 120, 122 return is again adjusted back to its braking positions shown in Fig. 16 in accordance with the maneuver discussed above with respect to the second deceleration state.

The logic element AND gate 502 now develops a positive output signal for driving to the driver S16 and for activating the clutch actuator solenoid valve 518. In response, the clutch 84 is turned on to mechanically lock the shafts 520 and 522 together with the gas generator and power turbine shafts 76, 82. The introduction of the logic element 470 in the electronic control module also ensures, in addition to the other previously described functions, that since the two shafts 520, S22 rotate at almost synchronous speeds, a relatively small lack of torque correspondence occurs across the coupling plates or discs 524, S26. . Consequently, the size of the coupling 84 may be relatively small.

It will thus be appreciated that the electronic control module 68 operates automatically first to increase the gas generator speed to substantially conform to the power turbine speed, and then to automatically return the guide rails to their braking position shown in Fig. 16 while the clutch 84 is turned on.

The interconnection between the gas turbine engine drive transmission and the gas generator shaft 76 causes the torque inertia of the gas generator 76 to contribute to decelerating the vehicle. It has been found that for an engine of the type described belonging to the power class 450-600 hp, this power-feedback-brake condition with approximately 200-250 braking horsepower contributes to the braking power of -200 hp generated by the setting of the guide rails 120, 122 in their position shown in Fig. 16. As the fuel regulator again greatly restricts the fuel flow 49 through the orifice 178, the fuel flow is regulated by the deceleration window 286 which allows the gas generator section to decelerate while maintaining the combustion process in the combustion chamber 98.

Reduction of the fuel flow thus achieves the deceleration effect of the torque inertia of the gas generator during the drive transmission of the vehicle. From the above it should be clear that the present invention provides considerable braking for deceleration purposes while still using the optimum operating characteristics of a gas turbine type gas turbine engine, with the gas generator section mechanically connected to the power turbine section only in a special situation with a manually selected "string" third type of deceleration state. During all deceleration conditions and the entire operation of the engine, a continuous combustion process is maintained in the combustion chamber. Significant deceleration is thus obtained without the combustion process therefore having to be extinguished.

This power feedback brake operation can be deactivated or interrupted in many ways: manually by opening switch 466 to stop the output of AND gate 506; providing a NO signal to turn off the driver 516 and the electromagnet 518 to disengage the clutch 84. If the manual switch does not open and the engine continues to decelerate, the element 474 is also operative to deactivate the power feedback operation as soon as the gas generator speed Edge reduced to a value below 45% of its maximum speed. Depressing the throttle to a set value in excess of a * also deactivates the power feedback drive by stopping an output signal from AND gate 506.

From the foregoing, it should now be apparent that the present invention provides an improved operating cycle for a gas turbine engine specifically designed to operate a ground-going vehicle in a safe, well-known manner while maintaining the inherent advantages of a gas turbine engine. More specifically, the use of a motor of the free-turbine type provides greater usability and the possibility of varying the operation of the engine. At the same time, the engine can be operated throughout its operating cycle while maintaining a continuous combustion process inside the combustion chamber 98. This avoids various operating problems and problems with the operating life associated with a repeated start and stop of the combustion process. The new cycle relates to an in-use of a combustion chamber 98 having throttled nozzles 104 to provide a variable pressure within the combustion chamber when the speed of the gas generator section is varied. The speed of the gas generator section is normally adjusted to a preselected value in relation to the position of the throttle control arm 184, while the guide rails 120, 122 are driven to adjust the turbine inlet temperature T4 to a preselected, substantially constant value to maintain high engine efficiency. Furthermore, the guide rail control is effective in indirectly changing the fuel flow through the fuel regulator 60 by changing the speed of the gas generator section so that the various actuators are driven in an integrated manner without counteracting each other. At the same time, an adjustment of the power turbine shaft speed Npt is achieved by means of the guide rail control 66.

It is further understood that the present invention provides a gas turbine engine which is particularly suitable for propelling a ground vehicle by rapidly responding acceleration similar to that obtained with a conventional internal combustion engine both by the automatic high speed operation and by the method of accelerating the gas turbine engine. This is accomplished by first changing the propulsion distribution to develop maximum power to the gas generator section. The setting control valve 61 is then operative in a regenerative manner to increase the fuel flow to the combustion chamber in such a way that the gas generator speed is increased while maintaining a substantially constant maximum turbine inlet temperature T4 and thereby achieving maximum acceleration without overheating of the engine. The setting valve also limits the T6 during the initial part of the acceleration when there is a "stopped" turbine condition. The acceleration is then terminated as soon as significant acceleration of the gas generator section has been achieved, by a change back of the power distribution to develop greater power over the power turbine wheels 116, 118.

It should be further noted that the present invention provides an improved method and apparatus for decelerating the vehicle in a three stage type of operation by first reducing the fuel flow, then adjusting the guide rails in the braking state and then by manually selecting the power feedback mode.

The primary functional elements of the fuel regulator 60; the setting valve 62 and the guide rail control 60 are hydromechanical in nature. This accomplishes, together with the operation of the electromagnet 426 in the guide rail control, as normal? . <~ t .aa i w w, e .I .¿'- _ y 5; azosvos-n is activated, an engine and a control system that is particularly suitable for achieving safe engine operation in the event of various fault conditions. In the event of a complete loss of electric power to the electronic control module 68, it is particularly true that the mechanical part of the fuel regulator 60 continues to adjust the fuel flow in relation to the fuel flow selected by the throttle control arm 184. The setting valve 62 is in no way affected by such an electrical fault. has the ability to regulate acceleration and / or deceleration to both prevent overheating of the engine during acceleration and maintain combustion during acceleration. The hydromechanical part of the guide rail control will remain effective in the event of an electrical fault, and has the ability to adjust the guide rails in a suitable manner to maintain functional motor operation. In the event of an electrical fault, the guide rail regulation becomes. electromagnet 426 deactivated, which results in loss of pressure on the surface 393 of the control piston 392. However, the speed control provided by the lever 396 is maintained and the guide rails can be adjusted in a suitable manner to maintain functional motor operation during this fault in the electrical system. It follows that although some desirable features of the engine control will be lost in the event of a power failure, the engine can still function properly with appropriate acceleration and deceleration, so that the vehicle can still be driven safely even with some possible loss of efficiency. and with lost ability to. achieve power feedback braking. From the foregoing, it will be apparent that the present invention provides an improved method of automatically adjusting and resetting the idle section of the gas generator section so that the engine responds quickly to developing increased output power, such as when it is desired to accelerate the vehicle. The present invention further provides an improved way to regulate the fuel flow hydromechanically in relation to the goose generator speed, as well as to take precedence over normal speed control for the fuel regulator, in order to increase or decrease the fuel flow due to the occurrence of various conditions which cause activation. of the electromagnets 239, 257. The present invention further provides an improved method of regulating fuel flow to the combustion chamber during acceleration, so that constant turbine inlet temperature T4 is maintained at all times, while the fuel flow is also regulated during deceleration to avoid exclusion. . \, Ng. bggrsw; tazosvos-o 52 Extinguishing of the combustion process inside the combustion chamber. The invention further relates to an improved way of regulating the guide rail setting in such a motor, both by hydromechanical drive for regulating the speed of a rotor; such as turbine wheels 116, 118, and by electric operation which takes precedence depending on the magnitude of the activation of the proportional electromagnet 426.

In the foregoing, a preferred embodiment of the invention has been described in sufficient detail for those skilled in the art to practice the invention.

However, the above detailed description is to be construed as merely exemplary in nature, and is not intended to limit the scope of the invention or its idea as set forth in the appended claims below.

Claims (21)

-åw,, S; ezosvosl-o Patentkrav A method of regulating the flow of fuel to a recuperative gas turbine engine (30) equipped with a combustion chamber (98), characterized by the adoption of the following measures: preheating the inlet air flow to the combustion chamber (98) by passing the flow through a recuperator (heat exchanger) (56) during heat exchange with exhaust gas flow from the engine; restricting outlet flow from the combustion chamber (98) to maintain pressure in the combustion chamber above ambient pressure; sensing the temperature from the inlet air flow to the combustion chamber and the overpressure maintained in the combustion chamber; and metering fuel flow during engine (30) acceleration as a function of both the sensed temperature and the sensed pressure. A method according to claim 1, characterized in that fuel flow is metered to maintain the inlet temperature of the recuperator (56) below a predetermined maximum value as soon as the sensed overpressure is below a predetermined level, and to maintain the combustion chamber (98). ) outlet flow temperature at a substantially constant maximum value as soon as the sensed overpressure exceeds the predetermined level. The method of claim 1 or 2, having a gas generator section (52) comprising a combustion chamber (98), characterized by means (56) arranged to supply heated compressed air to the combustion chamber (98), means (448) arranged to sense the temperature of the air supplied to the combustion chamber, and means (328) arranged to sense the overpressure prevailing inside the combustion chamber (98) and means (60, 62) arranged to regulate the flow of fuel to the combustion chamber, at least below a part of the engine (308). ) acceleration, as a function of the sensed temperature and the sensed pressure. Gas turbine engine, in particular gas turbine engine (30) for performing Engine according to claim 2, characterized in that the function of the temperature and the pressure constitutes a function of at least the product of the sensed temperature and the sensed pressure. 5. An engine according to claim 3 or 4, characterized in that the function of the temperature and the pressure is so selected that, during at least a part, of the acceleration of the engine (30), the temperature of the gas leaving the combustion chamber (98) is maintained constant. Engine according to claim 5, characterized in that the function (of temperature and pressure is so selected that the temperature of gas leaving the combustion chamber (98) is kept constant when the sensed pressure exceeds a certain value. 7. An engine according to claim 6, characterized in that the function is selected so that the temperature of the gas decreases with a decrease in the sensed pressure below the latter value. Engine according to one of the preceding claims, characterized in that when the sensed pressure is lower than a certain minimum value, the fuel flow has a minimum for the special sensed temperature, and constitutes a function of the sensed temperature but not of the sensed the pressure. Engine according to one of the preceding claims, characterized in that the engine (30) comprises a power turbine (54) arranged to be driven by gas from the gas generator section (52), and a recuperator (heat exchanger) (56), arranged to gas blown from the power turbine (S4) and to transfer heat from the blown gas to the air to be supplied to the combustion chamber (98). Engine according to Claim 9, characterized in that the function of temperature and pressure is chosen such that the temperature of the gas blown out of the power turbine (54) does not exceed a limit value. Engine according to claim 10, when dependent on claim 4, characterized in that the function of temperature and pressure is so selected that when the sensed pressure is below said certain value, the temperature of the gas blown out of the power turbine is (54) at or near limit value. Engine according to one of Claims 9 to 11, characterized in that the gas leaving the combustion chamber (98) is arranged to pass through fixed nozzles (104). Engine according to one of the preceding claims, characterized in that the fuel flow regulating means (60, 62) comprise two parts (276, 282), which are movable relative to each other, and each of which has an acceleration window (290): 284) “som i varie-« wm «¶mwew. To the extent that the acceleration window (284; 290) of the second part for regulating the fuel flow through the acceleration windows overlaps to the combustion chamber (98), the mutual movement between the two parts (276, 282) being a movement with two degrees of freedom, one degree of freedom being regulated by the sensed temperature, while the other degree of freedom is regulated by the sensed pressure. Engine according to claim 13, characterized in that the acceleration windows (284, 290) are generally rectangular. Engine according to claim 13 or 14, characterized in that the two parts of the fuel flow regulating means (62) comprise a valve housing (276) with a bore (278) resp. a hollow valve element (282) mounted inside the bore for longitudinal movement and rotational movement, which movements constitute the two degrees of freedom. Engine according to claim 15, characterized in that the pressure sensing means (328, 276) comprise a fluid pressure actuated actuator (316) having an outlet portion (338) movable in a direction transverse to the axis of the bore (278) in the valve housing (276), which outlet part (338) is so connected to the valve element (282) that the valve element is rotated in response to changes in the pressure in the combustion chamber (98). Engine according to claim 16, characterized in that the outlet part of the actuating member (316) comprises a piston, and is connected to the valve element (282) by means of a radially extending link (338) attached to the valve element, wherein a distance from the shaft part of this link located on the axis of the bore (278) engages in a groove in the exit part. Motor according to claim 16 or 17, characterized in that the output part of the actuator (316) is subjected to a force exerted by biasing means (330) and which counteracts the compressive force exerted on the output part of the sensed pressure. Engine according to one of the preceding claims, characterized in that the fuel flow regulating means (60, 62) are arranged such that upon deceleration of the engine (30) a combustion flow (98) is supplied to the combustion chamber sufficiently large to maintain combustion. "IW _31" azosvosèo S fl a Engine according to claim 19, characterized in that the fuel flow regulating means (60, 62) comprise a first metering orifice arranged to be regulated depending on the sensed temperature and the sensed pressure, wherein a regulator (60) is arranged in series with the first dosing opening, which regulator (60) during the deceleration of the engine (30) provides at most a very considerably restricted fuel flow path, and a second dosing opening which bypasses the regulator (60) and is arranged to regulate the bypass. they fuel flow as a function of at least sensed pressure. Engine according to claim 20, when this claim depends on claim 13, characterized in that the bore (278) in the valve housing (276) has three passages (142, 144, 290) which open into the housing (276). of which a passage (144) is connected to the regulator (60) for directing the flow of fuel through the regulator, and without any restriction communicates with the interior (288) of the valve element (282), a second passage (290) leading to the acceleration window in the valve housing (276), and a third passage (142) is arranged to direct the bypassed fuel flow, and opens into the bore (278) in the valve housing (276) in the form of a deceleration window which cooperates with a deceleration window ( 286) in the valve member (282) to control the flow of fuel between the second and third passages (290: 142) via the overlapping areas of the deceleration windows.