The present disclosure relates generally to engine starting, and, more particularly, to systems and methods for starting a gas turbine engine.
A gas turbine engine may have an ignition system that generates a spark to ignite a fuel-air mixture to start the engine. More specifically, an exciter may be used to provide a high voltage pulse signal to an igniter in a combustor of the engine, which causes a spark to be produced across a gap of the igniter. High voltage leads from the exciter to the igniter may be used to transmit the high voltage pulse signal. However, high voltage transmission may result in an electrical arc that could cause damage to the engine and/or other components connected to the engine.
As such, there is room for improvement.
In one aspect, there is provided a system for starting an engine. The system comprises: an electronic engine controller configured to output a first voltage signal comprising at least one pulse when commanded to start the engine, the first voltage signal having a maximum amplitude below an igniter voltage threshold; a voltage transformer coupled to the electronic engine controller and configured to transform the first voltage signal received from the electronic engine controller into a second voltage signal having a maximum amplitude equal to or above the igniter voltage threshold; and at least one igniter coupled to the voltage transformer and configured to ignite a fuel-air mixture in a combustor of the engine with the second voltage signal received from the voltage transformer.
In another aspect, there is provided a method for starting an engine The method comprises: generating, at an electronic engine controller, a first voltage signal comprising at least one pulse, the first voltage signal having a maximum amplitude below an igniter voltage threshold; transforming, at a voltage transformer, the first voltage signal into a second voltage signal, the second voltage signal having a maximum amplitude equal to or above the igniter voltage threshold; and igniting, by at least one igniter, a fuel-air mixture in a combustor of the engine with the second voltage signal.
Reference is now made to the accompanying figures in which:
It will be noted that throughout the appended drawings, like features are identified by like reference numerals.
With reference to
It should be appreciated that by providing a low voltage pulse signal from the EEC 210 to the voltage transformer 220, without the use of an exciter, that the reliability of the starter systems may be improved. This is because the low voltage pulse signal from the EEC 210 may be less likely to cause an electrical arc than the transmission of a high voltage signal by an exciter. Moreover, this configuration may also simplify the design of starter systems (e.g., by reducing installation requirements, dielectric margin requirements, hermetic sealing, and the like). Weight and/or cost savings may also be obtained by implementing the systems and/or methods described herein.
The EEC 210 is powered by one or more power sources. The power source may be a power bus, a battery or any other suitable power source. For example, one or more electrical buses of an aircraft may provide power to the EEC 210. The EEC 210 is configured to receive a command to start the engine 10. The command may be received from a control mechanism or an aircraft or engine computer. For example, the command may be received from a power lever or other control mechanism or computer in a cockpit of an aircraft. The EEC 210 provides the first voltage signal to the voltage transformer 220 by use of wiring 212, 214. In other words, the wiring 212, 214 couples the EEC 210 to the voltage transformer 220. The wiring 212, 214 is low voltage electrical wiring for transmission of the low voltage signals. For example, the wiring 212, 214 may be rated for low voltage transmission. The wiring 212, 214 may be provided as part of a harness of the engine 10 in order to electrically connect the EEC 210 to the voltage transformer 220.
The voltage transformer 220 may be any suitable passive electronic device that transforms the first voltage signal into the second voltage signal. In the illustrated embodiment, the voltage transformer 220 comprises a primary coil 221, a secondary coil 222 and a core 225. The primary coil 221 and the secondary coil 222 may be copper wiring or any other suitable wiring. The core 225 may be any suitable magnetic core (e.g., a laminated iron core, a solid iron core, or any other coil made of ferromagnetic material(s)). The primary coil 221 is wrapped around the core 225 a given number of turns N and the secondary coil 222 is wrapped around the core 225 a given number of turns M. The number of turns N and M may vary depending on practical implementations. In general, the number of turns N and M are set such that the voltage transformer 220 is able to amplify the first voltage signal into the second voltage signal having a maximum amplitude that is equal to or exceeds an igniter voltage threshold. The first voltage signal has a maximum amplitude that is below the igniter voltage threshold. The igniter voltage threshold is the threshold required by the igniter 230 to start the engine 10. In other words, the igniter voltage threshold corresponds to a value that if meet or exceeded causes the igniter 230 to generate a spark. The igniter voltage threshold may vary depending on practical implementations, as the igniter voltage threshold varies depending of the igniter used. In some embodiments, the voltage transformer 220 is an ignition coil, which is a specific type of voltage transformer used for engine ignition. The ignition coil may be configured to have an open magnetic circuit (i.e., the core 225 does not form a closed loop around the windings of the primary and secondary coils 221, 222).
In the illustrated embodiment, the wire 212 provides the first voltage signal from an output port of the EEC 210 to the primary coil 211. More specifically, a first end of the wire 212 is connected to the output port of the EEC 210 and a second end of the wire 212 is connected to a first end of the primary coil 221. The wire 214 grounds a second end of the primary coil 221 to the ground of the EEC 210. That is, a first end of the wire 212 is connected to the second end of the primary coil 211 and a second end of the wire 212 is connected to ground of the EEC 210. The wiring 212, 214 may vary depending on practical implementations.
In the illustrated embodiment, an ignition lead 232 is used to couple the voltage transformer 220 to the igniter 230. More specifically, a first end of the ignition lead 232 is connected to a first end of the secondary coil 222 and a second end of the ignition lead 232 is connected to the igniter 230 (e.g., to an electrode of the igniter 230). The ignition lead 232 is a high voltage electrical wire for transmission of the high voltage signals. The ignition lead 232 may vary depending on practical implementations. The second end of the secondary coil 222 is connect to ground. The ground connection of the secondary coil 222 may be electrically isolated from the ground of the EEC 210. For example, the secondary coil 222 may be grounded to the ground of the engine 10. In embodiments having more than one igniter, each igniter may have a separate ignition lead to the voltage transformer 220. In alternative embodiments, the igniter 230 is integrated with the voltage transformer 220. In other words, the igniter 230 may be coupled to the voltage transformer 220 without the use of ignition leads 232.
The igniter 230 is positioned in the combustor 16 of the engine 10. The igniter 230 is a device that is configured to deliver electric current from the second voltage signal to ignite a compressed fuel-air mixture in the combustor 16 by an electric spark. Any suitable igniter may be used. For instance, the igniter 230 may have a metal shell connected to ground and electrically isolated from a central electrode by an insulator. The electrode may protrude from the insulator into the combustion chamber 14 of the engine 10 for forming a spark gap when the second voltage signal is received. The igniter 230 may be referred to as a “spark plug”. The ground connection of the igniter 230 may be the same ground that the secondary coil 222 is connected thereto.
With reference to
The first voltage signal 250 is output by the EEC 210 for starting the engine 10, but has a voltage level insufficient for starting the engine 10 by the igniter 230 (i.e., the maximum amplitude of the first voltage signal 250 is below the igniter voltage threshold 240). Accordingly, the voltage transformer 220 amplifies the first voltage signal 250 to produce the second voltage signal 260. In the example of
Referring back to
In some embodiments, the EEC 210 may have two channels. With reference to
With reference to
In some embodiments, the first voltage signal is monitored to assess an electromagnetic field produced by the voltage transformer 220 on the first voltage signal. In some embodiments, the first voltage signal is monitored to detect that the at least on igniter 230 has produced a spark. In some embodiments, the first voltage signal is monitored to detect that the engine 10 has started. In some embodiments, the first voltage signal is monitored to detect that the at least on igniter 230 has failed to produce a spark. In some embodiment, the EEC 210 may detect that the engine has failed to start when the at least one igniter 230 has failed to produce a spark. In some embodiments, the first voltage signal is monitored to detect that the engine 10 has failed to start. In some embodiments, the first voltage signal is monitored to obtain at least one characteristic of the first voltage signal when ignition by the at least one igniter 230 is expected to occur. The at least one characteristic may be used detect that a spark has occurred or has failed to occur. The at least one characteristic may be used detect that the engine 10 has started or has failed to start.
With reference to
The memory 414 may comprise any suitable known or other machine-readable storage medium. The memory 414 may comprise non-transitory computer readable storage medium, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. The memory 414 may include a suitable combination of any type of computer memory that is located either internally or externally to device, for example random-access memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like. Memory 414 may comprise any storage means (e.g., devices) suitable for retrievably storing machine-readable instructions 416 executable by processing unit 412. In some embodiments, the computing device 400 can be implemented as part of a full-authority digital engine controls (FADEC) or other similar device, including an engine control unit, and the like.
The methods and systems for starting an engine described herein may be implemented at least in part in a high level procedural or object oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of a computer system, for example the computing device 400. Alternatively, the methods and systems for starting an engine may be implemented at least in part in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing at least in part the methods and systems for starting an engine may be stored on a storage media or a device, for example a ROM, a magnetic disk, an optical disc, a flash drive, or any other suitable storage media or device. The program code may be readable by a general or special-purpose programmable computer for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein. Embodiments of the methods and systems for starting an engine may also be considered to be implemented at least in part by way of a non-transitory computer-readable storage medium having a computer program stored thereon. The computer program may comprise computer-readable instructions which cause a computer, or in some embodiments the processing unit 412 of the computing device 400, to operate in a specific and predefined manner to perform the functions described herein.
Computer-executable instructions may be in many forms, including program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules may be combined or distributed as desired in various embodiments.
The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure.
Various aspects of the methods and systems for starting an engine may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and is therefore not limited in its application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments. Although particular embodiments have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects. The scope of the following claims should not be limited by the embodiments set forth in the examples, but should be given the broadest reasonable interpretation consistent with the description as a whole.