Helicopter turboshaft engine over-rotation protection inspection system and control method

Abstract

The invention belongs to the technical field of engine over-rotation protection, and particularly relates to a helicopter turboshaft engine over-rotation protection inspection system and a control method. The system comprises an engine control switch, an engine electronic controller and an over-rotation protection checking module. The engine control switch is provided with three gears, namely a parking gear, a slow ground gear and a flying gear; the engine electronic controller is connected with the output end of the engine control switch so as to collect gear signals of the engine control switch and control the rotating speed of the gas turbine according to the gear signals of the engine control switch. The output end of the engine electronic controller is connected with the over-rotation protection checking module and used for sending a control instruction to control whether the over-rotation protection checking module works or not. When the over-rotation protection inspection module works, all circuits of the over-rotation protection inspection module are inspected, whether open circuit, short circuit and overcurrent exist or not is judged, and the inspection result is fed back to the cabin displayer through the engine electronic controller.

Description

Technical Field

[0001] The invention belongs to the technical field of engine overspeed protection, and in particular relates to an overspeed protection inspection system and a control method for a helicopter turboshaft engine. Background Art

[0002] Helicopters rely on the shaft power output by the turboshaft engine to drive the rotor and tail rotor to rotate through the transmission system, generating the lift and anti-torque required for flight. In an aviation turboshaft engine, the compressor, combustion chamber and gas turbine form the engine gas generator. There is no mechanical connection between the gas generator and the power turbine, and the power turbine is driven by the gas generator. The power turbine is connected to the rotor and tail rotor through the transmission system to drive the rotor and tail rotor to do work. During normal flight, the helicopter changes the required power by changing the size of the collective pitch (rotor installation angle). The turboshaft engine changes parameters such as fuel flow to keep the output power consistent with the required power and maintain a constant rotor speed.

[0003] When a helicopter turboshaft engine overspeeds due to some abnormal conditions (the engine output shaft breaks and is disconnected from the transmission system, the engine fuel supply increases abnormally, etc.), the overspeed protection system will come into play, controlling the engine to reduce the fuel supply to reduce the engine power state, or directly cut off the engine fuel supply to stop the engine. Most domestic helicopter turboshaft engines are equipped with an overspeed protection inspection system, which is used to perform functional inspections of the overspeed protection system under non-overspeed conditions, so that the overspeed protection system can effectively play its role when overspeed occurs during helicopter flight. In the past, the domestic helicopter turboshaft engine overspeed protection system was to set an overspeed protection inspection button in the cockpit, and complete the overspeed protection inspection on the ground before daily flight. This inspection method not only consumes manpower, but also directly affects the execution of tasks when emergency tasks require rapid dispatch. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the existing overspeed protection system is time-consuming and labor-intensive. The present invention provides a system design and control method for automatically realizing the overspeed protection inspection of a helicopter turboshaft engine. The system function can be automatically inspected during the engine start and stop process.

[0005] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0006] A helicopter turboshaft engine over-speed protection inspection system, comprising: an engine control switch, an engine electronic controller, and an over-speed protection inspection module;

[0007] The engine control switch has three gears, namely parking, ground slowing and flying;

[0008] The engine electronic controller is connected to the output end of the engine control switch to collect the engine control switch gear signal, and controls the gas turbine speed according to the engine control switch gear signal. The output end of the engine electronic controller is connected to the over-speed protection check module to send a control instruction to control whether the over-speed protection check module works;

[0009] When the over-speed protection inspection module is working, it checks each circuit loop of itself to determine whether there is a circuit break, a short circuit or an overcurrent, and feeds back the inspection result to the cockpit display through the engine electronic controller.

[0010] Further, when the engine electronic controller detects that the engine control switch is switched from parking to ground slow, an engine start control signal is sent to the over-speed protection check module.

[0011] Furthermore, when the over-speed protection inspection module receives the engine start control signal and detects that the power turbine speed is in the range of 38% to 40% of the rated speed, it inspects each circuit loop of itself.

[0012] Further, the system also includes: a parking solenoid valve;

[0013] When the engine electronic controller detects that the engine control switch is switched from ground slow to parking, the engine electronic controller sends an over-speed parking signal to the over-speed protection check module.

[0014] Furthermore, when the over-speed protection check module receives an over-speed shutdown signal and the gas turbine speed is in the range of 69% to 71% of the rated speed, the shutdown solenoid valve is controlled to close, and the gas turbine speed reduction rate is detected; whether the shutdown solenoid valve is working normally is determined based on the gas turbine speed reduction rate.

[0015] Furthermore, the gas turbine speed reduction rate is detected within 0s to 2s after the control parking solenoid valve is closed.

[0016] A method for checking over-speed protection of a helicopter turboshaft engine is implemented by the system, and the method comprises the following steps:

[0017] Step 1: Detect the state of the engine control switch. When the engine control switch is switched from parking to ground slow, go to step 2; when the engine control switch is switched from ground slow to parking, go to step 4;

[0018] Step 2: The engine electronic controller sends a start control signal to the over-speed protection check module; the engine electronic controller detects the power turbine speed and sends it to the over-speed protection check module;

[0019] Step 3: When the overspeed protection inspection module receives the start control signal and the power turbine speed is in the range of 38% to 40% of the rated speed, it inspects each circuit loop to determine whether there is a circuit break, short circuit or overcurrent, and feeds back the inspection result to the cockpit display through the engine electronic controller;

[0020] Step 4: The engine electronic controller sends an over-speed stop signal to the over-speed protection check module, and the engine electronic controller detects the gas turbine speed and sends it to the over-speed protection check module;

[0021] Step 5: When the overspeed protection inspection module receives the overspeed parking signal and the gas turbine speed is in the range of 69% to 71% of the rated speed, the parking solenoid valve is controlled to close, and the gas turbine speed reduction rate is detected within 0s to 2s; the parking solenoid valve is determined to be working properly based on the gas turbine speed reduction rate; and the parking solenoid valve inspection result is fed back to the cockpit display by the engine electronic controller.

[0022] Furthermore, in step five, when the absolute value of the gas turbine speed reduction rate is greater than 10%, it is determined that the parking solenoid valve is working normally; otherwise, it is determined that the parking solenoid valve is working abnormally.

[0023] Furthermore, when the parking solenoid valve operates abnormally, the fuel metering valve is adjusted to the minimum position by the engine electronic controller to achieve parking.

[0024] Compared with the prior art, the present invention has the following technical features:

[0025] Automatic over-rotation protection check;

[0026] During the starting process, when the power turbine speed is 38%-40%, the over-speed protection circuit is automatically checked;

[0027] During the parking process, when the gas turbine speed is 70%, the parking solenoid valve is automatically checked;

[0028] For the inspection of the parking solenoid valve, a time criterion is introduced, which is within 0-2s when the parking starts.

[0029] For the inspection of the parking solenoid valve, the gas turbine speed reduction rate criterion is introduced, and the reduction rate is lower than -10% / s.

[0030] The scheme of the present invention utilizes the engine control signal to complete the engine overspeed protection inspection work through the overspeed protection inspection module. That is, there is no need to set up a special overspeed protection inspection switch in the cockpit and no need to carry out manual overspeed protection inspection. The overspeed protection inspection work can be automatically completed during the normal start and stop of the helicopter turboshaft engine, and the inspection results can be fed back to the helicopter display, which greatly reduces the preparation time before the helicopter flight and saves labor costs, and at the same time improves the maintainability of the overspeed protection inspection system to a certain extent.

[0031] The scheme of the present invention can effectively complete the over-speed protection check during each start-up and shutdown process through the automatic over-speed protection inspection method, and feedback the functional status of the over-speed protection system, thereby ensuring that the over-speed protection system can work normally if over-speed occurs during each helicopter flight, thereby improving the safety of the helicopter and the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a principle block diagram of a helicopter turboshaft engine overspeed protection inspection system;

[0033] Figure 2 The figure is a detailed schematic diagram of a helicopter turboshaft engine overspeed protection inspection system. DETAILED DESCRIPTION

[0034] The present invention discloses a helicopter turboshaft engine over-speed protection inspection system, which comprises three parts: system design, control design and operation steps.

[0035] System Design:

[0036] The helicopter turboshaft engine overspeed protection inspection system mainly includes the cockpit engine control switch, power turbine speed sensor, gas turbine speed sensor, engine electronic controller, overspeed protection inspection module, and engine parking solenoid valve. The system can realize the overspeed protection inspection function, including two inspection parts: one is the overspeed protection inspection module circuit inspection, which mainly checks the internal circuit open circuit, short circuit and overcurrent; the other is the parking solenoid valve, which mainly checks whether its function (fuel is cut off by closing the parking solenoid valve to stop the engine) is normal.

[0037] The engine control switch is a "three-speed" switch, which is set to "park", "ground slow" and "fly". The "park" gear position controls the engine to be in the parking state, the "ground slow" gear position is used to start the engine, and the "fly" gear position is used to accelerate the engine. When the engine control switch is switched from the "park" gear position to the "ground slow" or "fly" gear position, the corresponding control signal is output to the engine electronic controller to control the engine to enter the "ground slow" state or the "fly" state. When the engine control switch is in the "ground slow" gear position, the engine electronic controller controls the engine gas turbine speed to 70%; when the control switch is in the "fly" gear position, the engine power turbine speed is controlled to 100%.

[0038] When the engine needs to stop normally or when it stops due to overspeed, it is achieved by closing the engine fuel metering valve and the engine stop solenoid valve at the same time. The two serve as backup for each other, reducing the risk of the engine not being able to stop effectively.

[0039] Control Design:

[0040] The control principle of the turboshaft engine overspeed protection inspection system is as follows Figure 1 As shown. Among them, the engine electronic controller is used to control the engine working state and transmit the corresponding control instructions and signals to the engine overspeed protection inspection module; after receiving the corresponding control instructions and signals, the overspeed protection inspection module automatically executes the overspeed protection inspection program. The overspeed protection inspection program is divided into two stages: the first stage is the engine starting stage, in which the overspeed protection inspection module receives the engine starting control signal sent by the engine electronic controller and the power turbine speed is in the range of 38% to 40%, and automatically performs the overspeed protection circuit inspection (checking the circuit loop overcurrent, open circuit and short circuit). When the circuit is abnormal, the helicopter display shows "overspeed protection circuit inspection failed"; when the circuit is normal, the helicopter display shows "overspeed protection circuit inspection passed". The second stage is the engine stopping stage. In this stage, when the overspeed protection inspection module receives the engine "overspeed stop" control signal sent by the engine electronic controller and the gas turbine speed is at 70%, it automatically cuts off the fuel supply according to the control strategy of stopping the engine when the engine overspeeds, and issues a control instruction to close the parking solenoid valve to cut off the fuel supply to the engine. When the fuel is cut off normally (the gas turbine speed drop rate is lower than -8% / s within 0-2s at the beginning of starting), the parking solenoid valve is considered to be working normally, and the helicopter display shows "parking solenoid valve check passed"; when the gas turbine speed drop rate is not lower than -8% / s within 0-2s, the parking solenoid valve is considered to be working abnormally, and the helicopter display shows "parking solenoid valve check failed". At this time, parking is achieved only by relying on the engine electronic controller to control the fuel metering valve to the minimum position.

[0041] Steps:

[0042] The specific steps for checking the overspeed protection of a helicopter turboshaft engine are as follows:

[0043] Check and confirm the status of the helicopter and the engine, and that the engine control switch is in the "park" position;

[0044] Move the engine control switch from the "parking" position to the "ground slow" position, and the engine electronic controller transmits the start control signal to the over-speed protection check module;

[0045] The engine starts to start, the power turbine accelerates, the power turbine speed sensor measures the power turbine speed, and transmits the collected signal to the over-speed protection check module.

[0046] When the overspeed protection inspection module receives the start control signal (the engine control switch is switched from the "parking" position to the "ground slow" position) and the power turbine speed is between 38% and 42%, the overspeed protection inspection module starts to check the open circuit, short circuit and overcurrent of each circuit loop, and feeds back the inspection results to the helicopter cockpit display through the engine electronic controller in real time. If the inspection is successful, the helicopter cockpit display will show "overspeed protection circuit inspection passed", if the inspection fails, it will show "overspeed protection circuit inspection failed";

[0047] In the past, the inspection was not performed at a low speed of 38% to 40% of Np (power turbine speed), but after the engine was started to the rated speed (100%), the inspection switch was pressed to start the inspection.

[0048] Advantages: Automatic and timely detection at low speeds. On the one hand, there is no need to press the switch, which saves time and reduces the burden on the pilot. It is more conducive to timely detection of whether there is a fault in the over-speed protection module circuit, reduces the risk of over-speed after the engine is successfully started and cannot promptly determine whether the starting protection module is functioning normally, and increases the pilot's awareness time and disposal time.

[0049] When the helicopter lands after flight, turn the engine control switch from the "flight" position to the "ground slow" position;

[0050] At this time, the engine gas turbine speed is 70%. When you are ready to shut down the engine, turn the engine control switch from the "ground slow" position to the "parking" position. On the one hand, the engine is normally stopped, and on the other hand, the engine parking solenoid valve is tested.

[0051] In the past, this was achieved by pressing the over-speed protection check switch when the power turbine speed was 100%. This did not occur during the shutdown process when the gas turbine speed was 70%.

[0052] Advantages: The engine shutdown process itself is a working process of the parking solenoid valve from opening to closing. Combining it with parking inspection can not only achieve the purpose of inspection, but also be convenient, save time and effort.

[0053] When the gas turbine speed is 70% and the engine electronic controller receives the stop signal, within 0-2s, it will not immediately control the engine fuel metering valve to close to stop the fuel supply, but send an engine "overspeed shutdown" signal to the overspeed protection module.

[0054] When the overspeed protection module receives the engine "overspeed stop" signal from the engine electronic controller and the gas turbine speed is 70%, it immediately controls the parking solenoid valve to move in the closing direction to cut off the fuel supply and complete the inspection of the parking solenoid valve at the same time. The specific steps are as follows:

[0055] (1) When the gas turbine speed is 70% and receives the "overspeed stop" signal, the overspeed protection module sends a control signal to control the stop solenoid valve to close;

[0056] (2) At this time, the parking solenoid valve moves in the direction of closing, and the gas turbine speed begins to decrease. If the gas turbine speed decrease rate is less than -10% / s within the initial 0 to 2 seconds, it is considered that the parking solenoid valve is working properly, and the helicopter cockpit displays "parking solenoid valve inspection passed"; if the decrease rate is not less than -10% / s, it is considered that the parking solenoid valve is not closed in time and is abnormal, and the display shows "parking solenoid valve inspection failed";

[0057] The parking solenoid valve is checked by pressing the overspeed protection check switch when the power turbine speed is 100%. After observing that the gas turbine speed and the power turbine speed can drop to a certain fixed value, the check is considered to have passed, without adding time and drop rate criteria.

[0058] Benefits: In the past, the inspection of the parking solenoid valve could only detect whether the parking solenoid valve can move in the closing direction, but it was not possible to accurately detect the closing rate (whether it is closed in time: whether it is closed in place within the specified time). By specifying the rate of decrease of the gas turbine speed in the range of 0-2s at the beginning of parking, it is not only possible to determine whether the parking solenoid valve moves in the closing direction, but also to reflect the closing rate of the parking solenoid valve and whether the parking solenoid valve is closed in place in time. Even if the gas turbine speed begins to decrease, but the rate of decrease does not meet the requirements, the parking solenoid valve is still judged to be abnormal.

[0059] In an aviation turboshaft engine, the compressor, combustion chamber and gas turbine form the engine gas generator. There is no mechanical connection between the gas generator and the power turbine, and the power turbine is driven by the gas generator.

[0060] 1. The gas turbine speed is used when parking because the engine power state is characterized by the gas turbine speed, and the engine power is determined by the gas turbine speed. The engine changes from the "slow" state to the "parking" state because the engine fuel supply decreases, which reduces the engine power state. Therefore, the gas turbine speed is used to reflect this state change.

[0061] 2. The overspeed protection system is a system that implements engine shutdown protection when the power turbine speed exceeds the speed limit. The power turbine speed is used at the starting time, and it can also detect whether the power turbine speed signal is wrong.

[0062] If the parking solenoid valve is judged to be malfunctioning within 0-2s, the engine electronic controller will automatically control the engine fuel metering valve to close and stop the engine after 2s, avoiding the danger of the parking solenoid valve failing to function and the engine not being able to stop effectively.

Claims

1. A helicopter turboshaft engine overspeed protection inspection system, characterized in that: The system includes: an engine control switch, an engine electronic controller, and an over-speed protection check module; The engine control switch has three gears, namely parking, ground slowing and flying; The engine electronic controller is connected to the output end of the engine control switch to collect the engine control switch gear signal, and controls the gas turbine speed according to the engine control switch gear signal. The output end of the engine electronic controller is connected to the over-speed protection check module to send a control instruction to control whether the over-speed protection check module works; When the over-speed protection inspection module is working, it checks each circuit loop of itself to determine whether there is a circuit break, a short circuit or an overcurrent, and feeds back the inspection result to the cockpit display through the engine electronic controller.

2. The system according to claim 1, characterized in that: When the engine electronic controller detects that the engine control switch is switched from parking to ground slow, it sends an engine start control signal to the over-speed protection check module.

3. The system according to claim 2, characterized in that: When the over-speed protection check module receives the engine start control signal and detects that the power turbine speed is in the range of 38% to 40% of the rated speed, it checks each circuit loop of itself.

4. The system according to claim 3, characterized in that: The system further comprises: a parking solenoid valve; When the engine electronic controller detects that the engine control switch is switched from ground slow to parking, the engine electronic controller sends an over-speed parking signal to the over-speed protection check module.

5. The system according to claim 4, characterized in that: When the overspeed protection check module receives an overspeed stop signal and the gas turbine speed is in the range of 69% to 71% of the rated speed, the stop solenoid valve is controlled to close and the gas turbine speed reduction rate is detected; whether the stop solenoid valve is working normally is determined based on the gas turbine speed reduction rate.

6. The system according to claim 5, characterized in that: The gas turbine speed reduction rate is detected within 0s to 2s after the control parking solenoid valve is closed.

7. A method for checking overspeed protection of a helicopter turboshaft engine, the method being implemented by a system according to any one of the preceding claims, characterized in that: The method comprises the following steps: Step 1: Detect the state of the engine control switch. When the engine control switch is switched from parking to ground slow, go to step 2; when the engine control switch is switched from ground slow to parking, go to step 4; Step 2: The engine electronic controller sends a start control signal to the over-speed protection check module; the engine electronic controller detects the power turbine speed and sends it to the over-speed protection check module; Step 3: When the overspeed protection inspection module receives the start control signal and the power turbine speed is in the range of 38% to 40% of the rated speed, it inspects each circuit loop to determine whether there is a circuit break, short circuit or overcurrent, and feeds back the inspection result to the cockpit display through the engine electronic controller; Step 4: The engine electronic controller sends an over-speed stop signal to the over-speed protection check module, and the engine electronic controller detects the gas turbine speed and sends it to the over-speed protection check module; Step 5: When the overspeed protection inspection module receives the overspeed parking signal and the gas turbine speed is in the range of 69% to 71% of the rated speed, the parking solenoid valve is controlled to close, and the gas turbine speed reduction rate is detected within 0s to 2s; the parking solenoid valve is determined to be working properly based on the gas turbine speed reduction rate; and the parking solenoid valve inspection result is fed back to the cockpit display by the engine electronic controller.

8. The method according to claim 7, characterized in that: In the step 5, when the absolute value of the gas turbine speed reduction rate is greater than 10%, it is determined that the parking solenoid valve is working normally; otherwise, it is determined that the parking solenoid valve is working abnormally.

9. The method according to claim 8, characterized in that: When the parking solenoid valve works abnormally, the engine electronic controller adjusts the fuel metering valve to the minimum position to achieve parking.

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