Hydraulic Brake Valve Control for Engine Overspeed
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Solution Overview
Problem
Existing hydraulic brake systems for test benches of turboprops, turbofans, and helicopter engines face challenges in rapidly responding to changes in engine speed during transient states, leading to potential engine damage due to overspeed during acceleration or deceleration.
Innovation Solution
A regulated hydraulic brake system with an inlet valve control mechanism that combines a stabilized speed signal of an engine parameter with a signal representing the variation of another parameter, such as power or torque, to facilitate quicker response, utilizing proportional controlled valves and a PID controller for the outlet valve to manage fluid flow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional feedback-based valve control is used, then the system is stable and easy to control, but the response time is slow and cannot prevent engine overspeed during transient states
Solution Approach 1:
The control system calculates and stores a look-up table of inlet valve opening positions corresponding to different engine speeds and acceleration rates before operation. During transient states, the system directly references this pre-calculated table to determine the optimal valve opening position, eliminating the delay associated with real-time feedback processing and enabling immediate response to engine speed changes.
Solution Approach 2:
The invention replaces the traditional feedback-based mechanical control system with a feedforward control system that uses pre-calculated lookup tables and direct electronic control of the inlet valve. This substitution of control methodology dramatically reduces response time while maintaining system stability, as the control action is determined in advance rather than reacting to feedback delays.
2Reliability
If the inlet valve opens slowly to maintain stable water level, then the system remains stable, but the engine can overspeed during transient acceleration before the brake catches up
Solution Approach 1:
The control system uses pre-calculated lookup tables that determine the optimal inlet valve opening position based on the current engine speed and the desired acceleration rate. This allows the system to proactively adjust water admission to match engine power changes, ensuring the brake can immediately handle transient power increases without engine overspeed while maintaining stable operation during steady-state conditions.
Solution Approach 2:
The system dynamically adjusts the inlet valve opening position based on real-time engine operating conditions by referencing speed-dependent lookup tables. During transient acceleration, the valve opens more rapidly to increase water level and power dissipation capacity faster, while during steady-state operation, the valve maintains stable positioning. This dynamic adaptation resolves the contradiction between rapid response and stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enables faster and more dynamic response to engine speed changes, enhancing the test bench's operability and preventing engine damage during transient phases by quickly adjusting water admission, thus improving the system's ability to handle rapid power changes.
Implementation Method 1
a control system, preferably in closed loop, of the hydraulic brake outlet valve... the outlet valve control system includes a proportional-integral-derivative or PID controller controlling the closed-loop outlet valve based on the difference between a setpoint and a measured parameter
Implementation Method 2
the hydraulic brake consists of a rotor driven, possibly via a speed reducer, by the low-pressure shaft of the motor, this rotor generally rotating in the water. The quantity of water present in the brake replaces, for the duration of the tests, the variable resistance of the propeller
Data Source
Figure 1
AI summary
The brake has a regulating system (1) for regulating an inlet pneumatic valve (4), where the regulating valve is configured such that the inlet valve is actuated based on a control signal by adding an image signal i.e. engine power signal, of a stabilized rate of a parameter of an engine (2) and an image signal of variation of another parameter e.g. power required by a logic controller, of the engine. The image signal of the variation of the latter parameter of the engine is drift signal or a function representing the time variation of latter parameter of the engine.