Patent Application
20100006165
The present invention generally relates to pneumatic regulating valves, and more particularly to pneumatic regulating valves configured to control bleed air in a pneumatic system and the actuation and control of the pneumatic regulating valves.
A gas turbine engine may be used to supply power to various types of vehicles and systems. For example, gas turbine engines may be used to supply propulsion power to an aircraft. Many gas turbine engines include at least three major sections, a compressor section, a combustor section, and a turbine section. The compressor section, which may include two or more compressor stages, receives a flow of intake air and raises the pressure of this air to a relatively high level.
In addition to providing propulsion power, a gas turbine engine may also, or instead, be used to supply either, or both, electrical and pneumatic power to the aircraft. For example, some gas turbine engines include a bleed air port on the compressor section. The bleed air port allows some of the compressed air from the compressor section to be bled away from the compressor and diverted away from the combustor and turbine sections, and used for other functions such as, for example, the aircraft environmental control system, and/or cabin pressure control system.
Most modern commercial aircraft have numerous applications of pneumatic control valves including pressure regulating valves that are configured to control the flow of air bled from the engine compressor. For practical considerations, most commercial aircraft bleed air valves are actuated pneumatically using the same source of engine bleed air. These pneumatically actuated valves may experience reliability issues due to air contamination. In addition, in many instances the engine bleed air pressure may be low and necessitate the use of relatively large pneumatic actuators. There has been a trend in the aircraft industry to use hydraulic actuation, often incorporating jet fuel as the source of hydraulic power, to replace pneumatic actuators on some pneumatic valve applications. The fuel, or other hydraulic fluid, is inherently cleaner than bleed air, which reduces the likelihood of contamination problems. In addition, the hydraulic pressure is generally high, thus a smaller actuator can be used. The existing hydraulically actuated pneumatic valves typically use an electro-hydraulic servo valve (EHSV) and a linear variable differential transformer (LVDT) or rotary variable differential transformer (RVDT) for control, along with some form of electronic computer. These components can increase overall system weight and, concomitantly, overall system cost.
Hence, there is a need for a hydraulically actuated pneumatic regulator that may be used in a bleed air system that can be actuated more efficiently to control the bleed air extracted from the engine. In addition, there is a need for a pneumatic regulating valve that enables bleed air pressure to be controlled without the use of electronic control components.
The present invention provides a hydraulically actuated pneumatic regulator for control of fluid in a flow passage. In one embodiment, and by way of example only, the pneumatic regulator includes a valve element, a pneumatic-to-hydraulic servo, and an actuator. The valve element is disposed at least partially within the flow passage and movable to control a fluid flow therein. The pneumatic-to-hydraulic servo includes a hydraulic flow passage in fluidic communication with a hydraulic nozzle and fluidly communicates with a hydraulic inlet and a hydraulic outlet. The actuator is coupled to the valve element and the pneumatic-to-hydraulic servo. The actuator is responsive to one or more control signals supplied by the pneumatic-to-hydraulic servo to controllably move the valve element.
In another particular embodiment, and by way of example only, the pneumatic regulator includes a valve element, a pneumatic-to-hydraulic servo, a feedback conduit and an actuator. The valve element is disposed at least partially within the flow passage and movable to control fluid flow therein. The pneumatic-to-hydraulic servo includes a hydraulic flow passage in fluidic communication with a hydraulic nozzle, a flexible flapper in communication with the hydraulic nozzle, and a feedback pressure device in communication with the flexible flapper. The feedback pressure device is configured to disengage the hydraulic nozzle in response to a change in pressure and supply one or more control signals to control a flow of hydraulic fluid therethrough the hydraulic nozzle. The feedback conduit includes an inlet port in communication with the flow passage and the feedback pressure device. The actuator is coupled to the valve element and the pneumatic-to-hydraulic servo. The actuator is responsive to the one or more control signals supplied by the pneumatic-to-hydraulic servo to controllably move the valve element.
In yet another particular embodiment, and by way of example only, the pneumatic regulator includes a butterfly valve element, a pneumatic-to-hydraulic servo, a feedback conduit, and an actuator. The butterfly valve element is disposed at least partially within a bleed air flow passage and movable to control fluid flow therein. The pneumatic-to-hydraulic servo includes a hydraulic flow passage in fluidic communication with a hydraulic nozzle, a flexible flapper in communication with the hydraulic nozzle, and a feedback pressure device in communication with the flexible flapper. The feedback pressure device is configured to supply pneumatic signals generated by a differential pressure to disengage the hydraulic nozzle and control a flow of hydraulic fluid therethrough the hydraulic nozzle. The feedback conduit includes an inlet port in communication with the bleed air flow passage and the feedback pressure device. The actuator is coupled to the butterfly valve element and the pneumatic-to-hydraulic servo. The actuator is responsive to the pneumatic signals supplied by the pneumatic-to-hydraulic servo to controllably move the butterfly valve element.
Other independent features and advantages of the preferred hydraulically actuated pneumatic regulator will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein:
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. In this regard, although the present embodiment is, for ease of explanation, depicted and described as being implemented in an aircraft gas turbine engine bleed air system, it will be appreciated that it can be implemented in various other systems and environments.
Turning now to
Preferably, a bleed air duct 122 is coupled between the multi-stage compressor 102 and the pneumatic regulating valve 200. The bleed air duct 122 is in fluid communication with the multi-stage compressor 102. In one particular embodiment, the bleed air duct 122 includes a plurality of ducts, namely a low-pressure stage duct, a mid-pressure stage duct, and a high-pressure stage duct, each in fluid communication with a different stage in the multi-stage compressor 102. It will additionally be appreciated that the system 10 could be implemented with any number of bleed air ducts 122 coupled to more than three different compressor stages, if needed or desired.
In the illustrated embodiment, bleed air from the compressor 102 is supplied to the pneumatic regulating valve 200 via the bleed air duct 122. The pneumatic regulating valve 200 is coupled to the bleed air duct 122 and the downstream duct 123. The pneumatic regulating valve includes a hydraulic (fuel or other hydraulic source) actuator with integral pneumatic feedback control 300 for controlling the flow of air bled from the multi-stage compressor 102 to at least one downstream component 400. No matter its specific physical implementation, the pneumatic regulating valve 200 is configured to selectively allow bleed air from the bleed air duct 122 to be controlled and regulated. In contrast to typical hydraulically actuated pneumatic valves that may include a control unit, such as an EHSV and an LVDT or RVDT, in conjunction with a computer, that are configured to supply appropriate commands to a valve, the pneumatic regulating valve 200 includes the hydraulic actuator with integral pneumatic feedback control 300 that operates to control the flow of bleed air without the need for any further control unit.
Turning to
The position of the valve element 126 is controlled by the actuator 302, which may include a piston and rod 322, and an optional bias spring 324. The piston and rod 322 is coupled to the valve element 126 via the linkage 320 and is disposed in an actuator enclosure 326. The optional bias spring 324 is disposed between the piston and rod 322 and the actuator enclosure 326 and supplies a bias force to the piston and rod 322 that biases the linkage 320 and in turn moves the valve element 126. The control orifice 328 provides a restricted fluid communication between the hydraulic supply input 310 and the actuator opening chamber 318. The control orifice 328 may be included in the piston and rod 322 as shown or could be incorporated in the actuator enclosure 326. In addition to being an integral part of the control system the control orifice 328 allows for a continuous flow of hydraulic fluid through the valve actuator 302 which may provide cooling and also prevent the buildup of residue caused by heating of stagnant hydraulic fluid. The piston and rod 322 also includes a piston seal 319. A rod seal 321 (or multiple seals) is incorporated into the actuator enclosure 326.
As
The pneumatic-to-hydraulic servo 304 includes a flexible flapper 330, a hydraulic nozzle 312, an upper bellows 332, a lower bellows 333, an actuating rod 334, an optional additional feedback pressure device (a diaphragm is depicted) 313 and a calibration spring 336 disposed within a housing 338. The hydraulic nozzle 312 is in fluid communication with the hydraulic outlet 314 defined by the housing 338. The motion of the flexible flapper 330 with respect to the hydraulic nozzle 312 creates a variable hydraulic fluid flow metering area. The upper bellows 332 and lower bellows 333 are sealed and minimize hydraulic leakage at a pneumatic-to-hydraulic interface 339. As depicted the upper bellows 332 and the lower bellows 333 are exposed to ambient pressure via conduit 337 and optional conduit 340 respectively in the housing 338. Optionally the conduits 337 and 340 could instead be connected to a reference pressure source depending on the application requirements.
In an alternate embodiment, as best illustrated in
Referring again to
The piston and rod 322 will move due to forces created by differential pressure induced by the hydraulic flow through the actuator 302. Hydraulic fluid entering the actuator 302 through the hydraulic inlet 310 tends to push the piston and rod 322 upwards, pulling on the linkage 320 and closing the valve element 126. Hydraulic fluid passing on through the control orifice 328 tends to fill the actuator opening chamber 318 which will push the piston and rod 322 downwards, pushing on the linkage 320 and opening the valve element 126. Similarly, hydraulic fluid exiting the actuator opening chamber 318 through the hydraulic nozzle 312 via the flow passage 315 tends to drain the actuator opening chamber 318 causing the piston and rod 322 to move upwards pulling on the linkage 320 and closing the valve element 126.
The pressure of the bleed air 124 in the downstream duct 123 may be selectively directed to the pneumatic-to-hydraulic servo 304 and more particularly, to the feedback pressure device 313 to provide pneumatic control. The pressure acting on the feedback pressure device 313 results in an upward force applied through the actuating rod 334 to the flexible flapper 330 and is resisted by the force of the calibration spring 336. When the bleed air 124 pressure in the downstream duct 123 is high the force on the feedback pressure device 313 will overcome the force of the calibration spring 336 and bend the flexible flapper upward away from the hydraulic nozzle 312 increasing the hydraulic fluid flow out of the actuator opening chamber 318 ultimately causing the valve element 126 to move towards the closed position. Similarly, when the bleed air 124 pressure in the downstream duct 123 is low the force of the calibration spring 336 will overcome the force on the feedback pressure device 313 and the flexible flapper will bend downward toward the hydraulic nozzle 312 decreasing the hydraulic fluid flow out of the actuator opening chamber 318 ultimately causing the valve element 126 to move towards the open position.
Closing the valve element 126 tends to reduce the pneumatic pressure in the downstream duct 123. Similarly opening the valve element 126 tends to increase the pneumatic pressure in the downstream duct 123. Thus due to the combined functions of the pneumatic-to-hydraulic servo 304, the actuator 302 the valve element 126 and other associated features of the invention the pneumatic regulating valve 200 will reduce the pressure in the downstream duct 123 when it increases and similarly will increase the pressure in the downstream duct 123 when it decreases resulting in a nearly constant pressure control in the downstream duct 123.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention.
