Two lane engine control system

• US 4,716,531 A
• Filed: 06/02/1986
• Issued: 12/29/1987
• Est. Priority Date: 05/10/1983
• Status: Expired due to Fees

• Current Assignee: Dowty and Smiths Industries Controls Limited, Smiths Industries Public Limited Company
• Original Assignee: Dowty and Smiths Industries Controls Limited, Smiths Industries Public Limited Company
• Inventors: Eccles, Edward S., Saunders, Arthur F.
• Primary Examiner(s): Lall, Parshotam S.
• Application Number:
  US06/871,134
• Time in Patent Office: 575 Days
• Field of Search: 364/431.02, 364/187, 371/9, 60/243, 60/39.281
• US Class Current: 701/100
• CPC Class Codes: G05B 9/03 with multiple-channel loop, i.e. redundant control systems

Abstract

A control system for a gas-turbine engine has two parallel control units, either one of which can be switched to supply control signals to the engine in response to input signals, such as from the pilot'"'"'s control lever and from various sensors. Each unit has a limiter that limits the fuel supply to the engine if the engine speed approaches or exceeds a predetermined maximum. A monitor unit in each control unit detects when the limiter has assumed control of the engine for more than a predetermined time, and switches the system to control by the other control unit. The predetermined engine speed may be different for different settings of the pilot'"'"'s control lever. The monitor unit in such an arrangement, may receive signals in respect of the acceleration and deceleration of the engine and switch to the other control unit only when the speed is outside the predetermined speed for the pilot lever setting, and when the acceleration or deceleration is not such as to bring the speed back within the predetermined speed.

Claims

1. An engine control system comprising:

first and second control means;

means for supplying input signals to said first and second control means;

means for supplying output signals from one of said first and second control means to control operation of an engine in response to said input signals;

relay means connected intermediate said first and second control means and said engine, said relay means being operable to supply output signals to the engine from either said first control means or said second control means;

limiter means;

means for supplying signals representative of the actual performance of the engine to said limiter means independently of said first or second control means, the limiter means being operable to override control of said engine by said first or second control means, and said limiter means itself controlling operation of said engine not to exceed predetermined operational parameters, when the one of said control means then controlling the engine causes said engine to exceed said predetermined operational parameters;

monitor means having timer means therein, said monitor means providing an output response signal when the engine has been operated at said predetermined operational parameters for more than a predetermined period of time; and

means supplying said output response signal from said monitor means to said relay means to disconnect the one of said control means which is producing the limited control of said engine and to connect instead the other of said control means to said engine.

2. An engine control system according to claim 1, wherein said monitor means provides an output response signal when the engine has been operated for more than a predetermined time at a speed that is close to or beyond a predetermined maximum or minimum speed.

3. An engine control system according to claim 1, wherein the first and second control means are substantially identical.

4. An engine control system according to claim 1, wherein both the first and second control means include a respective processing unit, a relay, means connecting each said relay in series between the engine and the respective control means, a logic unit, and means connecting each logic unit to a respective relay to control switching of said relay.

5. An engine control system according to claim 4, including means supplying a first input signal to each logic unit in respect of operation of the respective monitor means, means supplying a second input signal to each logic unit is respect of operation of the other said logic units, and means supplying a third input signal to each logic unit in respect of malfunction of the respective processing unit.

6. An engine control system according to claim 5, wherein said system includes a manual switch, and means supplying a fourth input signal to each logic unit in respect of operation of said manual switch.

7. An engine control system according to claim 4, wherein each said processing unit produces a coded signal dependent on correct functioning of said processing unit, and wherein each control means includes a watchdog unit, means for supplying said coded signal to said watchdog unit, said watchdog unit producing an output signal in response to an error in said coded signal, and means supplying the output signal from the watchdog unit to the respective logic unit.

9. An engine control system according to claim 1 or 8, wherein the said predetermined operational parameter of the engine are different at different demanded speeds of the engine.

10. An engine control system according to claim 9, wherein the system includes means for deriving signals representative of the rate of change of an operational condition of the engine;

means supplying the rate of change signals to the monitor unit, the monitor unit providing the said output response signal only when the engine has been operated outside predetermined operational parameters for more than a predetermined time and if the rate of change of the operational condition is not such as to bring the operational condition within the predetermined operational parameters for more than a predetermined time.

11. An engine control system according to claim 10, wherein said operational condition is the actual engine speed, and wherein the said rate of change of the operational condition is the acceleration or deceleration of the engine.

12. An engine control system according to claim 10, including timer means that is switchable between two different times, means for providing a signal indicative that engine relight is being attempted, and means for switching said timer means to the longer of said different times if engine relight is being attempted.

8. An engine control system comprising:

first and second substantially identical parallel control lanes each of which includes a respective control means;

means for supplying nominally identical input signals to the control means in both of said control lanes;

relay means connecting either the first or second control lane to control an engine;

limiter means;

means for supplying signals representative of actual engine operation to said limiter means independently of the control means in said first and second control lanes, said limiter means being operative to override control of said engine by said first or second control lanes and said limiter means itself controlling the supply of fuel to said engine to limit operation of the engine when the demanded operation of said engine is such as to take it outside predetermined operational parameters;

monitor means;

means supplying signals to said monitor means indicative of control of said engine by said limiter means, said monitor means having timer means therein and providing an output response signal when the engine has been operated at said predetermined operational parameters for more than a predetermined period of time; and

means supplying said output response signal to said relay means to disconnect the control lane producing the limited control of said engine from the engine, and to connect instead the other of said control lanes to the engine.

13. An engine control system comprising:

first and second substantially identical parallel control lanes, each of said control lanes including a respective control means, means for supplying nominally identical input signals to said control means in both of said control lanes;

relay means for connecting either the first or the second of said control lanes to an engine to control the engine;

limiter means;

means for supplying signals representative of actual engine operation to said limiter means independently of said control means in said control lanes, said limiter means overriding control of said engine by the one of said control lanes that is then controlling supply of fuel to said engine to limit operation of the engine not to exceed first predetermined operational conditions, when the demanded operation of said engine is such as to take it outside said first predetermined operational conditions;

monitor means;

means supplying signals to said monitor means indicative of actual and demanded engine speed;

means supplying signals to said monitor means indicative of engine acceleration or decleration, said monitor means having timer means therein and providing an output response signal only when the engine has been operated for more than a predetermined time interval outside second predetermined operational conditions, which are different at different demanded speeds of the engine, and if the engine acceleration or decleration is not such as to bring the engine speed within the second predetermined operational conditions; and

means supplying said output response signal to said relay means to disconnect the control lane which is producing the limited control of said engine from the engine, and to connect instead the other of the control lanes to the engine.