Apparatus for controlling the rotary speed in turbo-jet engines for aircraft

• US 4,217,754 A
• Filed: 06/14/1979
• Issued: 08/19/1980
• Est. Priority Date: 01/22/1977
• Status: Expired due to Term

• Current Assignee: Bodenseewerk Gerätetechnik Gmbh
• Original Assignee: Bodenseewerk Gerätetechnik Gmbh
• Inventors: Wust, Peter, Wellern, Wilfried, Schmidt-Roedenbeck, Heiner
• Primary Examiner(s): Garrett, Robert E.
• Application Number:
  US06/048,690
• Time in Patent Office: 432 Days
• Field of Search: 60/39.28 R
• US Class Current: 60/39.281
• CPC Class Codes: F02C 9/28 Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed F02C9/30 - F02C9/38, F02C9/44 take precedence
• CPC Class Codes: F02C 9/32 characterised by throttling of fuel F02C9/38 takes precedence
• CPC Class Codes: F05D 2270/02 to control rotational speed (n)
• CPC Class Codes: F05D 2270/101 Compressor surge or stall

Abstract

A control device produces a control deviation signal representing the difference between the commanded engine speed and the actual engine speed. Before this signal is applied to a fuel control unit to establish the rate of fuel flow to the engine, its time derivative is limited to a value substantially proportional to the distance that the operating state of the engine is from the surge line. In one embodiment the control deviation signal is differentiated with a lag corresponding to the lag of the fuel control unit before effecting said limiting and, after said limiting is effected, is integrated with a lead corresponding to said lag.

Claims

1. In an apparatus for controlling the rotary speed in jet engines for aircraft and comprising:

a rotary speed sensor which provides a rotary speed signal representing the rotary speed of the high-pressure compressor of the jet engine,

a commanded value generator which provides a commanded value signal representing a commanded rotary speed,

a control device, to which the rotary speed signal and the commanded value signal are applied and which provides a control deviation signal,

a fuel control unit controlled by the control deviation signal for controlling the rate of fuel flow supplied to the jet engine,

a pressure ratio generator for generating a pressure ratio signal which represents the pressure ratio of the outlet and the inlet pressures of the high-pressure compressor,

a mass flow sensor for generating a mass flow signal representing the mass flow of the jet engine,

a function generator which provides the surge line of the jet engine or a surge line limit curve running at a safety margin therefrom in the form of a limit pressure ratio signal as a function of the mass flow signal, and

signal limiting means between control device and fuel control unit for effecting limitation of the control deviation signal in accordance with the surge line distance obtained as difference of the limit pressure ratio signal and the pressure ratio signal,

the improvement comprising;

said signal limiting means limiting the time derivative of the fuel flow rate to a value substantially proportional to the surge line distance.

2. In an apparatus as set forth in claim 1,

wherein the fuel control unit has a predetermined transient response,

including means between the control device and the signal limiting means for differentiating the control deviation signal with a lag, which lag is equal to said transient response of the fuel control unit, and

including means between the signal limiting means and the fuel control unit for integrating the limited control deviation signal with a lead corresponding to said lag.

3. Apparatus for the control of acceleration processes in aircraft gas turbine engines of the type having a compressor (32) operating in front of a combustion chamber (36) and a turbine (34) operating behind the combustion chamber (36), and having a fuel control unit (38) for supplying a fuel flow rate (M) to the combustion chamber (36), the apparatus comprising means (46, 44, 68) for measuring the actual ratio of pressures (p₂, p₁) at the outlet and the inlet of the compressor (32) and providing output signal values (p₂ /p₁) indicative thereof, means (70) for comparing the actual measured compressor pressure ratio signal values (p₂ /p₁) with predetermined pressure ratio signal values (p₂ /p₁)_PG for an operating range of the engine, which predetermined pressure ratio signal values are set below the ratio level signal value (surge line) corresponding to compressor surge over the operating range of the engine, and for providing a difference signal value surge line distance (Δ

α

=(p₂ /p₁)_PG -(p₂ /p₁)) therefrom, and means (56, 58,

     60) receiving a signal (kΔ

α

)proportional to said difference signal value (Δ

α

) and the metered fuel flow value (B) from a speed governor of the engine for limiting the fuel flow during acceleration such that said predetermined pressure ratio signals (surge line limit curve) are not exceeded, said limiting means including means (56, 58,

     60) for limiting the time derivative (M) of the fuel flow rate (M) to a value (kΔ

α

) proportional to said difference signal value (Δ

α

).