|
The accessory drive is a gearbox that forms part of a gas turbine engine. Although not part of the engine's core, it drives the accessories, fuel pumps etc., that are otherwise essential for the operation of the engine or the aircraft on which it is mounted. Accessory drives on large engines handle between 400–500 hp. Power for the accessory drive is taken from the central shaft linking the turbine and compressor sections of the engine. This requires an internal gearbox that couples the drive to a radial driveshaft or ''towershaft'' that drives an external gearbox. == Internal gearbox == The design of the internal gearbox is complicated by the heat and small space available in which to connect the driveshaft. It is usually placed between the compressor outlet and the combustor. In turboprops or designs with centrifugal compressors, it may be placed ahead of the compressor. For two-shaft designs, an accessory drive will be taken from the high pressure shaft,〔 i.e. the outer and shorter of the two concentric shafts. This shaft comes up to speed more quickly when the engine is started. The drive and accessory gearboxes may also be split in two, one driven from each engine shaft, so as to distribute their loads. The engine-critical systems, including the starter drive, are arranged on the high-pressure shaft, with aircraft systems on the low-pressure shaft.〔 The high-pressure shaft also rotates faster than the low-pressure shaft, which may influence the distribution of accessories. To allow for thermal expansion, the drive from the main shaft may be taken by one of three means:〔 * direct drive, by a bevel gear on the main shaft. * stub shaft drive, where a tubular stub shaft is fitted over the main shaft and driven from it by splines. This stub shaft carries the bevel gear that drives the radial shaft. * idler shaft drive, a narrow shaft runs parallel to the main shaft. It is driven by spur gears and in turn drives the bevel gear to the main gearbox. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Accessory drive」の詳細全文を読む スポンサード リンク
|