Aero-engine starting control method based on torque measurement

Abstract

The invention discloses an aero-engine starting control method based on torque measurement. The aero-engine starting control method comprises the following steps: S1, measuring a torque value required by an engine in a starting state; s2, the engine starting process is divided into three stages according to the time sequence, a control torque model of engine starting is established, and fitting constants in the control torque model are fitted through the torque values collected in the S1; s3, correcting the control moment model in the S2 by atmospheric pressure to obtain a corrected control moment model; and S4, an alternating current motor is adopted to provide starting torque for the engine, and the alternating current motor outputs a torque value according to the control torque model in the S3. According to the method, the requirements for accessories and methods in the aero-engine starting process are lowered, due to the fact that the torque is adjustable, the adaptability to different working conditions and environments is enhanced, the starting efficiency and the fuel economy are improved, and a new thought and a new solution are provided for intelligent control over the aero-engine.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft engine testing, and in particular is an aircraft engine starting control method based on torque measurement. Background Art

[0002] Starting control is one of the key technologies of aircraft engine test control system. It is used on engine test benches and aircraft accessories such as gas turbine starters and air turbine starters to start and control the engine on the ground. After the starting system is driven, the output torque overcomes the engine resistance to achieve effective starting. Therefore, the resistance torque during the starting process of aircraft engines will have a direct impact on the selection of starters and starting performance. The reference standards of the starting system are described in detail in GJB 241A-2010, GJB2187A-2015, and HB 6630-92.

[0003] The existing engine starting system has the following problems:

[0004] First, whether it is a gas turbine starter, an air turbine starter or even an electric motor starter used in some small engines (hereinafter referred to as a starting accessory), they are all part of the aircraft starting system, which has a high cost and as a finished product accessory, cannot meet the engine starting requirements under special parameter requirements.

[0005] Second, the traditional starting system indirectly controls the output torque characteristics of the starting system by controlling the fuel flow, air flow, power supply voltage, etc. of the gas turbine starter, but is unable to measure the specific output torque of its accessories. If starting tests are required through starters of different power levels in the process of aircraft engine design to find out the boundary of the engine's starting torque, it will consume a lot of resources, and the test cycle and cost will be long.

[0006] Third, after long-term use, the starting accessories will cause their performance to deteriorate, and their output torque will also change, causing the engine starting time to be too long. The traditional starting method cannot determine whether the engine starting time is too long due to the engine itself or the starting accessories, and cannot evaluate the difference. Summary of the invention

[0007] The present invention aims to design an aircraft engine starting control method based on torque measurement to solve the three problems mentioned in the background technology.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] An aircraft engine starting control method based on torque measurement comprises the following steps:

[0010] S1, measures the torque value required when the engine is starting;

[0011] S2, the engine starting process is divided into three stages according to the time sequence, and the control torque model of the engine starting is established according to the following formula, and the fitting constants in the control torque model are fitted by the torque values ​​collected in S1:

[0012]

[0013] In the above formula, T is the torque, a, b, c are all fitting constants, t is time, t1 and t2 are the two time points when the torque is the maximum value and zero value during the engine starting process, and t1<t2;

[0014] S3, correct the control torque model in S2 with atmospheric pressure or temperature, and obtain the corrected control torque model as follows:

[0015]

[0016] or

[0017] In the above formula, T is the torque, a, b, c are all fitting constants, t is time, t1 and t2 are the two time points when the torque is the maximum value and zero value during the engine starting process, and t1<t2, P H is the current ambient atmospheric pressure, P B TEP is the ambient atmospheric pressure when measuring the torque required for engine starting in S1. H is the current ambient temperature, TEP B The ambient temperature when measuring the torque value required for the engine starting state in S1;

[0018] S4, using an AC motor to provide starting torque for the engine, and the AC motor outputs a torque value according to the control torque model in S3.

[0019] Furthermore, in said S1, the starting state of the engine includes false start, cold operation and normal start.

[0020] Furthermore, S1 also includes establishing a starting torque output characteristic diagram of the starting accessory based on the relationship between torque and time using the measured torque value, taking the time corresponding to the maximum torque position in the diagram as t1, and taking the time corresponding to the torque reduction to zero position in the diagram as t2.

[0021] Furthermore, in S4, the frequency of the frequency converter is used to control the rotation speed of the AC motor, thereby obtaining the output torque value of the control torque model in S3.

[0022] Furthermore, in S4, the output end of the AC motor directly drives the gear shaft of the accessory transmission device to rotate, and is directly connected to the engine transmission device through the torque transmission shaft, thereby driving the engine transmission device to start.

[0023] Furthermore, the method also includes feeding back the current torque value to the AC motor control end through the torque transmission shaft, and then adjusting the speed of the AC motor through the frequency converter to control the output torque of the AC motor.

[0024] Compared with the prior art, the aero-engine starting control method based on torque measurement of the present invention has the following characteristics:

[0025] (1) The present invention reduces the requirements for accessories and methods during the aircraft engine starting process. In the traditional engine starting process, a gas turbine starter or an air turbine starter is generally used, which requires a fuel system and a gas turbine starter or an air generator and an air turbine starter. The starting process is divided into an electric system, a control system, a fuel system, etc., while the starting method of the present invention only requires electricity, a motor, and a control system. The starting process uses the control logic of the invention, which is simpler and more effective, saving a large number of accessories while simplifying the starting control method.

[0026] (2) The present invention has enhanced adaptability under different working conditions and environments because the torque is adjustable.

[0027] (3) The present invention improves starting efficiency and fuel economy, and provides new ideas and solutions for the intelligent control of aircraft engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a block diagram of the starting torque test system in the present invention;

[0029] Figure 2 It is the schematic diagram of the starting control in the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above-mentioned technical ideas of the present invention, various modifications, substitutions and changes made according to the common technical knowledge and customary means in the field are included in the scope of the present invention.

[0031] The torque-based aircraft engine starting control method mainly includes the following steps:

[0032] S1, measure the torque required for normal engine starting; and form the starting torque output characteristic diagram of the standard starting accessories. Including false start, cold operation, normal start, etc. of the engine. Torque measurement reference Figure 1 Taking the starting curve (starting torque output characteristic diagram) of the air turbine starter as an example, the torque reaches its maximum value 1.5s after starting, then gradually decreases, and the torque drops to zero at 54s.

[0033] S2, using the measured torque value to reversely fit to obtain the basic control torque model of the engine start, the model is the motor output torque basic control model, which satisfies the following three-segment function:

[0034]

[0035] Among them, a, b, and c are all fitting constants. Combining the above formula and using the similarity principle to correct environmental changes (under different atmospheric pressures or temperatures, the rotational inertia of the engine rotor is basically the same, while the drag torque is different due to different atmospheric pressures or temperatures, which makes the input torque different), the basic control theory model of the engine is obtained;

[0036] At the beginning of starting, the output torque and the torque required by the engine increase rapidly with time. At this time, in order to prevent excessive engine shaft stress caused by excessive starting torque, the maximum torque output is limited on the basis of the output shaft torque model to prevent mechanical damage to the engine shaft connection; in the second stage of starting, as the engine speed increases, the required torque gradually decreases. After the engine is successfully ignited, the required power will be further reduced. After t>54s, regardless of whether the engine starts successfully or not, the motor output power is cut off to ensure the safety of the entire system in a no-load mode.

[0037] S3, starting control principle as follows Figure 2 As shown, Figure 2 In the figure, torque T is the model torque value, which is a function of time. Atmospheric pressure (or temperature, atmospheric pressure is selected in this embodiment) is used as a correction to obtain the target torque value. The motor speed is controlled by controlling the frequency of the inverter. The output torque is measured on the motor output shaft. The torque must conform to the model calculated value.

[0038]

[0039] T is the output torque, t is the time, P H is the current ambient atmospheric pressure, P B is the ambient atmospheric pressure when the starting torque is measured in S1.

[0040] Atmospheric pressure P H Make corrections to the environment. When the current atmospheric pressure is higher, the engine requires more power. When the atmospheric pressure is lower, the engine requires less power.

[0041] S4, by replacing the original starting accessories with an AC motor, using a frequency converter to control the speed of the AC motor to drive the engine to start; the output end of the AC motor drives the gear shaft of the accessory transmission device to rotate, and directly connects to the engine transmission device through the torque transmission shaft, thereby driving the engine transmission device to start. The torque transmission shaft has a protective function, and will break when the corresponding torque is exceeded, protecting the transmission system and the engine.

[0042] The torque is fed back to the AC motor control end through torque transmission, and then the AC motor speed is adjusted through the inverter to accurately control the output torque of the AC motor.

[0043] Take an engine in cold running condition of aviation material starting as an example, the atmospheric pressure is 85.2kPa, and the starting time is 54s. Figure 1 Record the starting torque output characteristic diagram of the starting accessories under this actual situation.

[0044] According to the torque value in the starting torque output characteristic diagram, the fitting constants a, b, and c in the control torque model (three-segment function) are fitted to obtain the following model:

[0045]

[0046] The unit of t is seconds.

[0047] Under the atmospheric condition of 87.3 kPa, the output torque of the control torque model is corrected to:

[0048]

[0049] The unit of t is seconds.

[0050] During the actual starting process, the torque is fed back to the motor control end using a torque meter, and the motor output torque is controlled according to the control model. When the engine is successfully ignited, the torque is steadily reduced according to the control model curve. After the engine reaches a stable working state, the motor smoothly transitions to no-load rotation, completing the entire starting mode. During this process, key data during the starting process is recorded for subsequent performance analysis and optimization.

[0051] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. Although the illustrative specific embodiments of the present invention are described above to facilitate the understanding of the present invention by the technical personnel in the field, it should be clear that the present invention is not limited to the scope of the specific embodiments. For ordinary technicians in the field of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. An aircraft engine starting control method based on torque measurement, characterized in that: The following steps are involved: S1, measures the torque value required when the engine is starting; S2, the engine starting process is divided into three stages according to the time sequence, and the control torque model of the engine starting is established according to the following formula, and the fitting constants in the control torque model are fitted by the torque values ​​collected in S1: In the above formula, T is the torque, a, b, c are all fitting constants, t is time, t1 and t2 are the two time points when the torque is the maximum value and zero value during the engine starting process, and t1<t2; S3, correct the control torque model in S2 with atmospheric pressure or temperature, and obtain the corrected control torque model as follows: or In the above formula, T is the torque, a, b, c are all fitting constants, t is time, t1 and t2 are the two time points when the torque is the maximum value and zero value during the engine starting process, and t1<t2, P H is the current ambient atmospheric pressure, P B TEP is the ambient atmospheric pressure when measuring the torque required for engine starting in S1. H is the current ambient temperature, TEP B The ambient temperature when measuring the torque value required for the engine starting state in S1; S4, using an AC motor to provide starting torque for the engine, and the AC motor outputs a torque value according to the control torque model in S3.

2. The method for controlling the start of an aircraft engine based on torque measurement according to claim 1, characterized in that: In S1, the engine start state includes false start, cold operation and normal start.

3. The method for starting an aircraft engine based on torque measurement according to claim 1, characterized in that: The S1 also includes establishing a starting torque output characteristic diagram of the starting accessory based on the relationship between torque and time using the measured torque value, taking the time corresponding to the maximum torque position in the diagram as t1, and taking the time corresponding to the torque reduction to zero position in the diagram as t2.

4. The method for starting an aircraft engine based on torque measurement according to claim 1, characterized in that: In S4, the frequency of the frequency converter is used to control the rotation speed of the AC motor, thereby obtaining the output torque value of the control torque model in S3.

5. The method for starting and controlling an aircraft engine based on torque measurement according to claim 1, characterized in that: In S4, the output end of the AC motor directly drives the gear shaft of the accessory transmission device to rotate, and is directly connected to the engine transmission device through the torque transmission shaft, thereby driving the engine transmission device to start.

6. The method for starting and controlling an aircraft engine based on torque measurement according to claim 5, characterized in that: It also includes feeding back the current torque value to the AC motor control end through the torque transmission shaft, and then adjusting the speed of the AC motor through the frequency converter to control the output torque of the AC motor.

Images