Abstract:
An engine thrust management system comprising an engine control device, an aircraft flight manual, a flight management device and a cockpit instrument device. The engine control device is operable to calculate a percent maximum available thrust parameter and a percent indicated thrust parameter. The aircraft flight manual is operable to calculate a required thrust parameter. The flight management device is operable to calculate a percent thrust setting target parameter and a percent commanded thrust parameter. The percent commanded thrust is the amount of thrust requested by an aircraft operator. The percent commanded thrust is varied by the operator according to the value of the percent thrust setting target parameter and the value of the percent indicated thrust parameter in order to produce optimal thrust. The engine thrust management system promotes operating efficiency by eliminating redundant processes found in conventional thrust management systems and is applicable to a wide variety of engines and aircraft, thus promoting common cockpit display architecture.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention generally relates to aircraft control systems. In particular, the present invention relates to a design architecture for aircraft engine thrust management.  
       BACKGROUND OF THE INVENTION  
       [0002]     Conventional aircraft engine thrust management involves the use of several design processes, such as engine power management in an engine electronic control, thrust limit computer and flight management computer functions of an aircraft information management system, and an aircraft flight manual used for providing aircraft dispatch information. Although all of these processes are connected with three fundamental elements of engine thrust management (i.e. an engine thrust setting target, a commanded engine thrust, and a calculated engine produced thrust), the functional requirements of these processes are unique and do not constitute a system for thrust management on an aircraft.  
         [0003]     Conventional engine thrust management is based on either the engine pressure ratio (EPR) or engine rotor speed (N1) parameters. Consequently, conversion back and forth between the three basic thrust elements and EPR or N1 is required. This results in unnecessary duplication and dependency of tasks implemented in each process. Further, implementation of a power management design for different engine types has to be incorporated repeatedly in all three processes. Cockpit display of the thrust setting indication is also different between different aircraft due to different engine types and/or different engine operating modes.  
         [0004]     A conventional engine thrust management system is illustrated in  FIG. 1  at  10 . The conventional system  10  generally comprises an engine power management process  12 , an engine electronic control  14  (EEC) located on aircraft engines (not shown), a flight management computer  16  located onboard an aircraft (not shown), and an electronic aircraft flight manual  18  (AFM), located remotely from the aircraft. The engine power management process  12  establishes the maximum rating power setting parameter (PSP) data, which is in terms of EPR or N1, at block  20  using two inputs. The first input, illustrated at block  22 , comprises characteristics of the maximum available thrust (FN) and the PSP. The second input, illustrated at block  24 , comprises the engine specification thrust or engine required thrust. The data developed at block  20  is duplicated in blocks  25 ,  29 , and  35 .  
         [0005]     The engine electronic control  14  computes the maximum rated PSP at block  26 . The maximum rated PSP pre-defined at block  20  is loaded into the engine electronic control  14  and is used for an engine fuel control parameter at block  28 . Thus, by computing the maximum rated PSP at step  26 , the EEC is performing a redundant operation with the engine power management process  12 , which is a resource consuming process.  
         [0006]     The FMC  16  also performs various redundant and resource consuming operations. Specifically, at block  30  the FMC  16  computes the maximum rated PSP, which is also performed at block  26  of the EEC  14 . The target PSP at block  30  is also computed at block  36 . At block  32  the FMC uses an EPM module to compute the available thrust (FN) and the power setting parameter (PSP), which requires the predetermined data at block  22 . At block  34  the FMC computes thrust used in calculations of takeoff V-speeds and aircraft performance predictions, which is a reverse operation with process  12 . Thus, the FMC  16  performs numerous redundant calculations, which are wasteful of computing resources and the process  12  must be completed prior to the development of the FMC  16 .  
         [0007]     The AFM  18  computes the required engine thrust at block  36 . At block  38 , the AFM  18  includes an EPM module that calculates the maximum available thrust FN and the power setting parameter PSP. Thus, block  38  performs the same operations as are performed at block  32  of the FMC  16  and also requires the pre-determined data block  22 . At block  40  the AFM  18  computes the maximum rated PSP and the setting target PSP. Thus, the operations of blocks  26 ,  30 , and  40  are redundant. At block  42 , the AFM  18  computes thrust used in calculation of takeoff V-speeds, which is a reversed operation with process  12 . The AFM  18  performs numerous redundant calculations, wasteful of computing resources and the process at block  12  must be completed prior to development of the AFM  18 .  
         [0008]     Thus, there is generally a need for an engine thrust management system that improves aircraft development flow time and aircraft performance capabilities. In particular, there is a need for an engine thrust management architecture that aligns the requirements and eliminates unnecessary redundant tasks across the three main components of engine thrust management. There is also a need for providing a common thrust setting indication that supports the common cockpit display concept.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention provides for an aircraft engine thrust management system comprising an engine control device, an aircraft flight manual, a cockpit instrument device and a flight management device. The engine control device is operable to calculate a percent maximum available thrust parameter and a percent indicated thrust parameter. The aircraft flight manual is operable to calculate a required thrust parameter. The cockpit instrument device is operable to provide a percent commanded thrust parameter. The flight management device is operable to calculate a percent thrust setting target parameter. The percent commanded thrust is the amount of thrust requested by an aircraft operator. The percent commanded thrust is varied by the operator according to the value of the percent thrust setting target parameter and the value of the percent indicated thrust parameter in order to produce an optimal amount of thrust for a particular mission.  
         [0010]     The present invention further provides for a method for managing aircraft engine thrust using percent thrust as the thrust indication parameter. The method comprises calculating a percent maximum available thrust parameter using an input from an aircraft sensor signal and an engine sensor signal, calculating a percent indicated thrust parameter using an engine produced thrust parameter, calculating a required thrust parameter using aircraft dispatch information, calculating a percent thrust setting target using the required thrust parameter, calculating a percent commanded thrust parameter using operator commands, and altering the percent commanded thrust parameter based upon changes in the percent thrust setting target to produce an optimal amount of thrust for a particular operation.  
         [0011]     The invention still further comprises a method for controlling the thrust of an aircraft. The method comprises referencing a percent thrust setting target parameter representing the percent amount of thrust required to perform a specific operation and altering a percent commanded thrust parameter representing the percent amount of thrust requested to perform the specific operation so that the percent commanded thrust parameter at least substantially equals the percent thrust setting target. Using this method, an optimal engine thrust needed to perform a particular operation is produced in response to the altering step, the intensity of the engine thrust produced being represented by a percent indicated thrust parameter.  
         [0012]     The invention further provides for a robust design process and system for engine thrust management without unnecessary duplication of functions. The process also accelerates design flow time and accommodates the common cockpit display concept.  
         [0013]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0015]      FIG. 1  is a block diagram illustrating the components of a conventional engine thrust management system and the general interaction between the components;  
         [0016]      FIG. 2  is a block diagram illustrating the components of an engine thrust management system according the current invention and the general interaction between the components; and  
         [0017]      FIG. 3  is a block diagram providing a more detailed illustration of the components of the system of  FIG. 2  and the operation of the components of  FIG. 2 , the system uses percent thrust as a thrust indicator parameter in an aircraft control loop. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0019]     With initial reference to  FIG. 2 , an overview of the thrust management system of the present invention is generally illustrated at  100 . The system  100  generally comprises an electronic engine control (EEC)  102  associated with an aircraft engine (not shown), a flight management computer (FMC)  104  typically located onboard an aircraft (not shown), aircraft instruments  105  and an aircraft flight manual (AFM)  106  typically located at a ground control station. The EEC  102  obtains the maximum rated thrust data at block  108  from block  120  of the aircraft flight manual  106 . The EEC  102  includes a thrust characteristic at block  110  for converting the commanded thrust to an engine fuel control parameter at block  114 . The EEC  102  and the FMC  104  compute the maximum rated thrust parameters at  112  and  116  respectively. The FMC  104  also computes a thrust setting target at block  116  for use in computing the maximum rated thrust parameter, also at block  116 . The FMC  104  may simply download the maximum rated thrust data at  113  from the EEC  102  where this data is defined at block  108 . Further, data computed at  116  is directly used for computing takeoff V-speeds and aircraft performance predictions at block  118 . At block  122 , the AFM  106  computes required thrust based on engine specification thrust  120  and the thrust computed at  122  is used directly in the calculations of block  124  where the AFM  106  computes takeoff V-speeds. Using percent thrust as a thrust indicating parameter, the EEC  102 , FMC  104 , and the AFM  106  do not perform duplicative operations.  
         [0020]      FIG. 3  is a detailed diagram of the closed loop operation of the engine thrust management system  100 . The thrust system  100  centers around the aircraft cockpit display  126 , which is associated with aircraft instruments  105 . The cockpit display  126  displays important parameters associated with the operation of the thrust management system  100 . For example, the cockpit display  126  includes a percent maximum available thrust Pm (often referred to as a percent maximum available rated thrust), a percent thrust setting target Ps, a percent indicated thrust parameter Pi, and a percent commanded thrust Pc. Generation and use of these parameters displayed at the cockpit display  126  is described below.  
         [0021]     As seen in  FIG. 3 , the EEC  102  receives sensor signals Y from the aircraft and sensor signals X from the engine. The sensor signals X and Y are redundant air data sources in some applications and may be various different parameters. The aircraft sensor signals are typically measurements of aircraft speed, altitude, and air temperature. The sensor signals X and Y are processed by the EEC  102  at block  126 , which is encompassed by block  108  of  FIG. 2 , to calculate the maximum thrust available Tx in light of the engine conditions and the maximum thrust available Ty in light of the aircraft conditions. At block  128 , which is encompassed by block  112  of  FIG. 2 , the maximum rated thrust Tx is divided by the maximum rated thrust Ty and the result is multiplied by 100 to determine the percent maximum available thrust Pm. Under normal conditions, and when the sensors are operating properly, Ty and Tx are equal and the percent maximum available thrust is 100%. If Ty and Tx are not equal, this alerts the operator that either the engine or the sensors are malfunctioning and further diagnostic testing is required.  
         [0022]     At block  130  the system  100  calculates the commanded thrust Tc. Tc is calculated by multiplying the percent commanded thrust Pc by the maximum rated thrust Ty (as calculated by the aircraft sensor signals Y) and dividing the result by 100. The Tc is typically calculated in pounds, but may be calculated using any other suitable measurement system.  
         [0023]     At block  132 , which is encompassed by block  114  of  FIG. 2 , the engine fuel control system processes the target thrust Tc and provides the proper amount of fuel required to achieve the target thrust Tc. The amount of calculated thrust representing the engine thrust actually produced is Tp. While engine power is being accumulated to reach Tc, Tp does not initially equal the target thrust Tc.  
         [0024]     At block  134 , the actual thrust Tp is divided by the maximum rated thrust Ty, as determined using the aircraft sensor signals Y, and the result is multiplied by 100 to produce the percent indicated thrust Pi. The Pi indicates the amount of engine thrust produced as a percentage of the total available thrust. This parameter is the output of the control loop and is displayed to the operator via the cockpit display  126  of the aircraft instruments  105 .  
         [0025]     The percent thrust setting target Ps is also displayed to the operator via the cockpit display  126 . Ps is calculated at block  136  of the flight management computer  104  using the maximum available thrust Ty and the required thrust Tr. The maximum available thrust data used in computing Ty may be uploaded from block  126  of the EEC  102  or may be calculated independently at block  138 , which is encompassed by block  114  of  FIG. 2 .  
         [0026]     The required thrust Tr is calculated by the AFM  106  at block  140 . The AFM  18  receives aircraft dispatch information, typically from a ground station. The dispatch information includes any information related to the operation of the aircraft, such as, but not limited to, the payload weight, drag coefficient, runway length, altitude, ambient conditions, number of passengers, etc. While the AFM  106  typically receives most, if not all, of this dispatch information from the ground station, at least a portion of the dispatch information, such as the maximum rated thrust data, may also be uploaded from the EEC  102  and the FMC  104 . The required thrust Tr is the amount of thrust that the aircraft needs to obtain a predetermined aircraft operational performance level. It is different for different aircraft missions. For example, the required thrust Tr for takeoff is greater than the required thrust Tr for cruising.  
         [0027]     The percent thrust setting target Ps is specifically calculated at block  136  by dividing the required thrust Tr by the maximum available thrust Ty and multiplying the result by 100. The percent thrust setting target Ps is the amount of thrust needed to perform particular operations, such as take-off, climb, cruise, and landing. Since the limit of Tr is Ty, the value of Ps cannot exceed 100%. The percent thrust setting target Ps is displayed to the aircraft operator(s) at the cockpit display  126  of the instruments  105 . Calculation of the percent thrust setting target Ps at block  136  is encompassed by block  116  of  FIG. 2 .  
         [0028]     The operator inputs his/her thrust commands via a device, such as an engine throttle lever of aircraft instruments  105 , which is in communication with the EEC  102  and the flight management computer  104 , by manipulating the throttle resolve angle (TRA). Alternatively, thrust commands are generated by an auto throttle system at block  144 . The percent commanded thrust Pc is calculated at block  142 . Block  142  receives an input representing the degree to which the operator has manipulated the throttle to generate the percent commanded thrust parameter Pc that the operator requested to achieve the target Ps, which is displayed to the operator at the cockpit display  126 .  
         [0029]     Use of the thrust management system  100  using percent thrust as the thrust setting parameter to operate an aircraft will now be described. The operator first references the cockpit display  126  to make sure that the Pm is at 100%, indicating that the aircraft and engine systems are operating properly. The next parameter referenced is the percent thrust setting target Ps, which varies according to the particular phase of flight that the aircraft is in, such as take-off, cruise, descent, landing, etc. The operator then references the percent indicated thrust Pi to determine the thrust actually being produced by the engines at the particular moment in response to his/her commanded thrust Pc. If Pc and Ps are not equal, the operator manipulates the throttle resolve angle to request additional or reduced thrust as appropriate to vary the percent commanded thrust Pc. The operator continues to manipulate the throttle resolve angle as necessary to change the percent commanded thrust Pc until it equals the percent thrust setting target Ps. After the engine has an opportunity to respond to the operator&#39;s commands, the percent indicated thrust Pi will equal Pc as well as Ps. After parameters Ps, Pc, and Pi are equal, no further action is required by the operator because the engine is producing the proper amount of thrust for the particular operation at hand. As operating conditions change Ps will change, thus requiring the operator to again vary the Pc and repeat the above process to insure that the proper amount of thrust is provided.  
         [0030]     Thus, the present invention provides for a system and method  100  for controlling the thrust of an aircraft engine using percent thrust as the thrust setting parameter. The system and method  100  generally includes an engine electronic control  102 , a flight management computer  104 , a cockpit instrument device  105  and a digital flight manual  106 . The system and method  100  eliminates the inefficiencies and redundancies of conventional thrust management systems and the thrust logic of the system is contained in the engine electronic control  102 , thus providing engine manufacturers with flexibility in designing their engine control. Specifically, the system and method  100  eliminates redundant engine power management modules of conventional flight management computers  16 , and aircraft manuals  18  to convert a thrust setting target EPR or % N1 to a calculated thrust value. Further, the system and method  100  provides for engine control in terms of the percent thrust (% FN) parameter and eliminates the cumbersome use of the conventional thrust setting parameter N1 or EPR. Use of % FN is more efficient because it provides for a commonality in the thrust setting parameter (PSP) and thrust indication system that can be used throughout the different aircraft systems regardless of the engine application and eliminates the need to convert back and forth during operation of the system  100  between percent thrust values and PSP values. Still further, the present invention enhances the common cockpit display concept and the common thrust management architecture because the percent thrust setting parameter is used for the thrust setting indication system regardless of the airplane type, engine type, operating mode, etc. The system  100  further eliminates the need for calculation of the thrust setting target parameter in the AFM  106 . The system  100  does not compromise any features of the existing airplane design, nor operational rules and certification regulations.  
         [0031]     While various preferred embodiments have been described, those skilled in the art will recognize modifications or variations which might be made without departing from the inventive concept. The examples illustrate the invention and are not intended to limit it. Therefore, the description and claims should be interpreted liberally with only such limitation as is necessary in view of the pertinent prior art.