FR2508670A1 - CLOSED CIRCUIT CONTROL SYSTEM FOR THE TOPPING OF THE FINS OF A GAS TURBINE ENGINE - Google Patents

Abstract

THE DEVICE FOR CONTROLLING THE CLEARANCE BETWEEN THE TOPS OF THE ROTARY FINS OF A ROTOR OF A GAS TURBINE ENGINE AND THEIR COOPERATING SEALING BANDAGE, INCLUDES AN ADJUSTING DEVICE 38 RECEIVING MEASURED OPERATING VARIABLES OF THE ENGINE INDICATIVE OF THE ENGINE CONDITIONS TRANSIENT OPERATION AND AT CONSTANT SPEED OF THE ENGINE AS WELL AS A SIGNAL REPRESENTING THE CURRENT CLEARANCE AT THE TOP OF THE FINS WHICH IS COMPARED WITH THE INPUT SIGNALS IN ORDER TO PRODUCE AN ERROR SIGNAL USED TO MOVE THE SEALING BANDAGE IN RELATION TO THE TOPS FINS.

Description

The invention relates to an active control system for the game.

  to the tops of the fins of a gas turbine engine which controls the clearance between the tops of the rotor fins and their cooperating sealing band and in particular it relates to a reactive closed circuit system

to the dimensions of the current game.

  For reasons of good engine performance and

  better fuel economy the industry is doing

  of concerted efforts to minimize the game

  the rotor fins and their sealing bandage

  neat in gas turbine engines This minimizes air or engine working leaks, leaks

  which are caused by the flow of air or medium

  place of work around the compressor or turbine fins instead of passing between these fins Obviously

  energy loss can be directly translated into pena-

  lity of engine performance and, as a result,

  in higher fuel consumption.

  For example, a system for minimizing these losses is described in U.S. Patent 4,069,662 which describes and claims an active system for controlling the game and which provides for blowing air against the side

  outside of the motor housing to cause it to shrink

  to reduce the play under certain operating modes

  engine operation This patent from the United States of America

  relates to an open circuit control system which

  monitors the engine speed and / or barometric pressure and which opens the cooling air valve when a predetermined engine operating mode is reached,

  that is to say the operating mode when cruising.

  The object of the present invention is to improve the system described in United States patent 4,069,662 by incorporating a closed circuit control system. The present invention proposes to measure the current clearance of the fins of the rotor, whether the rotor of the compressor and / or the turbine, and changes the clearance until it corresponds to a programmed value, for the mode

  transient or constant speed operation

  sequence, a detection means can detect and transmit

  be a signal representing the current game at a desired location

  re of the engine, for example the clearance between the tops of the first row of the turbine fins and their sealing band, towards the clearance control device Ce

  control device compares the measured clearance, such as

  detected by the detection means, with the desired clearance and ac-

  operates a clearance adjustment mechanism via a control means until the current clearance is

  equal to the desired game The desired game is determined by the dis-

  positive game control in response to in-

  coming from the engine control means and / or the cockpit.

  The object of the invention is to provide a turbo engine.

  gas bine with an advanced system to control the clearance between the rotor fins and the sealing bandage

surrounding these fins.

  According to the invention a closed circuit control system is provided which acts according to a discontinuous program as a function of a signal produced by the device for adjusting the fuel supply or inside the cockpit of the aircraft by positioning maneuvers carried out by the pilot or aircraft maneuvers, the circuit being closed by positioning the sealing bandage

depending on the clearance measured.

  The invention will now be described in greater detail with reference to the accompanying drawings, in which: FIG. 1 is a diagram representing the principle of the invention, and

  FIG. 2 is a partial representation, in par-

  tie in elevation and partly in section, of the

game detection.

  The invention is described in combination with a means for controlling the clearance between the tops of the fins and their sealing band by blowing air against the crankcase, but it is obvious that d other means without departing from the scope of the invention In addition, although a means of optical measurement

  is used according to the preferred embodiment for me-

  play the game at the tops of the fins, other ways to

  measure the clearance at the tops of the fins can be

  bent without departing from the scope of the invention.

  As can be seen from Figure 1, the invention is shown as being used in a fan-powered reaction motor, but it is obvious that it could

  can also be used in other engines The engine shown

  felt in FIG. 1 and designated as a whole by 10 comprises a central casing 12 containing a section of compressor, burner and turbine, this motor also comprising a casing 14 forming a bypass pipe and

  containing the fan For simplicity,

  engine details have not been shown because they are not part of the present invention -However, for other details of a suitable engine reference may be made to the JT-9 D engine manufactured by Pratt & Withney Aircraft Group,

  a division of the United Technologies Corporation,

  health of this patent application.

  The central casing 12 of the engine may be provided with several flanges 16 spaced axially from each other and extending towards the outside of the casing. Between these flanges 16 are mounted blow bars 18 having several holes for directing cooling air against the casing flanges The blowing of the cooling air against these flanges is used to shrink or dilate the c: irter so as to move the attached sealing bandage

  to the housing relative to the tops of the fins of the tur-

  bine The blowing bars 18 are supplied by a common distributor 20 connected to a pipe 22 Part vl Ste the air discharged from the fan in the pipe 24 is received in dynamic air intakes 26 and directed towards the pipe 30 which supplies exhaust air from the

  fan to distributor 20 Depending on the mode of

  preferred embodiment of the present invention of discharged air

  fan is used but it is obvious to the specialist

  list that other cooling media can be used to shrink or expand the casing or to move the sealing band relative to the tops of the rotor fins Means of mechanical contraction can also be used without leaving the frame

of the invention.

  The system described above is similar to the system described in United States patent 4,069,662 and for further details reference may be made to this United States patent. According to the present invention an appropriate regulating valve, designated as a whole by 34, is used to regulate the flow of cooling air

  supplied to line 22 and distributor 20 A means

  in appropriate control 36 is used to control the position

  of valve 34 which can be moved from a position

  fully open to a fully closed position

  and who can also occupy intermediate positions.

  The control means 36, in turn, is controlled

  by an appropriate control device 38 of the circled type

cooked closed.

  The input signals provided by lines 39 and 40 represent the desired clearance at the tops of the fins with respect to its sealing band required by controlled signals indicative of any change in the clearance between the tops of the fins and the sealing band and some

  current dimension of this game supplied to the

  control by line 42 In other words, the control device will produce an error output signal always when a difference between the current game and the desired game is observed. Input signals are supplied to the

  game control device via line 40 from

  _e of a manual control means located in the cockpit, or by

  another source, such as a feed adjuster

  - "fuel supply, via line 39 I) different modes

  operating modes are possible Depending on a mode of operation

  preferred operation, the feed adjustment device

  fuel is programmed to provide a signal

  representing the desired game according to the operating mode-

  engine operation For example, the control device

  of the motor has as input signals the operating parameters

  constant and transient operation of the motor, such as the rotational speed of the rotor, the pressure, the pressure ratio and the temperature Based on these signals 3 ′ 2 tréeh according to a preferred embodiment, a signal _-5 _ representing the desired clearance is formed for selected operating conditions of the engine in "cruise" or "climb" In addition, in the case of rapid changes in the operating conditions, for example during accelerations and decelerations, a signal of desired game is

  trained to increase play during periods of operation

  transient motor operation This signal is used in normal system operation, but it may be

  substituted by a manual signal sent to the cockpit which can

  put to provide, for example, a greater clearance during takeoff, 1 landing or during other special maneuvers. The game control device 38 compares the signal representing the desired game received by lines 39 or 40 with the signal representing the current game, received by line 42. It then produces a difference or an error signal which it transmits by line 41 to the control device 36 of the control system valve The control device 36 then actuates the valve in one

  direction to reset the error signal to zero.

  The fuel supply control system can take any form, such as, for example, the JFC-60 or JFC-68 manufactured by Hamilton Standard, a division of United Technologies Corporation, and an already calculated available signal can be used to produce a desired or programmed game control signal. According to the preferred embodiment, electronic control means, such as that described in US Patent 3,797,233 is exemplary of a means of preferred control This type of control medium is about to be programmed to determine

  the game for many maneuvers and operating conditions

  to which an aircraft engine may be subjected.

  The detection device or the proximity probe

  50 used to measure the dimension of the game and its trans-

  associated conductor 51 provide the signal representing the current clearance, which signal is transmitted to the

game control -

  A suitable detection means to measure the di-

  mension of the game is shown in Figure 2, according to-

  6- which laser proximity sensor 50 is mounted

  in an opening 48 made in the sealing bandage

  tee 52 mounted in proximity to and surrounding a turbine fin represented in part by 54 Because the invention

  is not limited to the use of such a pro-

  ximity, and because other devices to measure the

  current game can also be used, a description of

  this probe is not incorporated in this description

  for clarity purposes An optical proximity sensor

  is described in ISA Bulletin ASI 74228 (133-

  ) published in 1974 and entitled "Laser Proximity Probes for the Measurement of Turbine Blade Tip Running Clearance" by W Drinkuth, W G Alwang and R House, which can be

  refer for a more detailed description of such

  optical measurement probe Such a probe comprises a slow

  shines with a prism to focus a laser beam on the tops of the fins The image due to the refraction of the laser beam through the prism is transmitted to the top of

  the fin and it is reflected backwards by the grip

  me and the lens to an optical receiving fiber En

  knowing the dimension of the game in the non-de-

  row, moving the image to the end of the fi

  optical reception bre is measured which allows

  complete the variation of the play, which is transformed in the transducer 51 to form the signal representing the play

  current and supplied to the control device 38.

  It is obvious that the invention is not limited to the particular embodiment described above, but that many variations or modifications can be made therein.

  made without departing from the scope of the invention.

Claims (4)

  1 Backlash control device to check the backlash between the tops of rotating fins of a gas turbine engine and the sealing band surrounding the wings.   rotating lettes, comprising means for placing the ban-   tightness in relation to the tops of the fins in   a predetermined distance, the first functional means   in response to operating conditions of the mo-   tor to form a program to choose this predetermined distance for the different operating modes   of the engine, second means operating in response to the-   said predetermined distance to provide a signal represented   feeling the current game, operating means operating   in response to the error between the first pleas and the   conds means to control the positioning means   to place the sealing band at a predetermined distance   completed to eliminate this error.   2 control device according to claim 1,   having a fuel supply adjustment system   rant to measure predefined operating parameters   engine and to adjust the fuel supply   rant towards the engine according to a responsive program   to the engine operating parameters, said pre-   miers means operating in response to a signal represented   both the desired clearance formed by the device for adjusting the fuel supply and manual means actuated by an operator being provided to render said first means incapable of producing an output signal for the control of the control means.   3 Control device according to claim 2, characterized in that the means for producing said signal indicative of the current play is an optical proximity probe used to focus a laser beam on the tops of the rotating fins, this laser beam being reflected towards a transducer used to produce an indicative signal   distance traveled in comparison to a value of predetermined reference.   4 Closed circuit control device for the clearance at the tops of the fins of a 7 'qaz turbine engine -8-   fan comprising a casing supporting several rotors   tors having fins and sealing bandages surrounded   rants fins and attached to the housing, a fan casing surrounding the motor fan, means for blowing exhaust air from the fan against   the motor housing and comprising several blowpipes   flage arranged around the casing, conduit means connecting the casing of the fan to the blowing bars to channel exhaust air from the fan to the blowing bars in order to direct this air against the casing, and a means of valve arranged in said means   line to regulate the air flow in it, the-   said control device, with a closed circuit, of the clearance at the tops of the fins comprising first means operating in response to operating conditions of the engine to produce a corresponding desired clearance signal   to the desired clearance for a predefined operating condition   completed in the range of operating modes of the mo-   second means operating in response to the current clearance between the tops of the fins and their sealing band cooperating to provide a current clearance signal, means operating in response to the first means and the second means for producing a signal error, and means operating in response to this error signal to control said valve means to adjust the air flow to cause radial movement of the housing to   change the game at the tops of the fins until the- said error be eliminated.   Control system according to claim 4, comprising   carrying a fuel supply adjustment device   - operating in response to function parameters -   engine to measure the fuel supply to the engine according to the requirements of the latter and for   provide a desired play signal between the rotatable fins   ves and their associated sealing bandage, and by means to be actuated by an operator to render said signal   desired game inoperative and to control said means of support   pope independently at the desired game signal provided   by the fuel supply adjustment device.   Dû / î 7 l -i A c 9 ct'a C-C M DU P J 13 C -r LIA) d O p C t 6 z t / / & v'X 4, l: AP, 2