Electromechanical Brake Actuator Current Saturation
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Solution Overview
Problem
The existing electromechanical aircraft brake actuators require oversizing to accommodate varying temperatures, leading to increased mass and volume due to the need for high torque at low temperatures and reduced mechanical losses at high temperatures, resulting in mechanical stress and potential damage.
Innovation Solution
A method to dynamically adjust the electrical current saturation value based on the internal temperature of the electromechanical braking actuator, increasing it during cold operation and decreasing it during hot operation to maintain optimal force without exceeding mechanical limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the saturation current is set to a high maximum value for cold operation, then the actuator can provide sufficient torque when cold, but the mechanical stresses in the transmission chain become excessively high during hot operation
Solution Approach 1:
The saturation current value is made dynamic rather than fixed. The control unit continuously monitors the temperature of the electromechanical actuator and adjusts the saturation current threshold accordingly. When the actuator is cold, a higher saturation current is permitted to overcome the high viscosity of the lubricant. When the actuator is hot, the saturation current is reduced to prevent excessive mechanical stresses, thus resolving the contradiction between providing sufficient cold-start torque and protecting against hot-operation stress
Solution Approach 2:
The electrical parameter (saturation current) is changed based on temperature conditions. The control unit modifies the current saturation threshold as a function of the measured temperature, allowing the system to adapt its electrical characteristics to thermal conditions. This parameter change enables the actuator to deliver appropriate torque at different temperatures without subjecting the mechanical transmission to damaging stress levels
2Ease of operation
If the saturation current is set to a high maximum value, then the actuator can operate effectively at low temperatures, but the mass and volume of the equipment must be increased to handle the stresses
Solution Approach 1:
The system uses dynamic current saturation adjustment based on temperature feedback, eliminating the need for oversized mechanical components. By controlling the electrical current threshold dynamically, the actuator can operate effectively across temperature ranges without requiring increased mass or volume of mechanical parts to handle peak stress conditions
Solution Approach 2:
The patent replaces mechanical oversizing (increasing mass and volume of transmission components) with an electrical control solution. Instead of building a larger, more robust mechanical transmission to handle worst-case stress conditions, the system uses intelligent current saturation control to prevent excessive stresses from occurring in the first place, substituting mechanical redundancy with electrical intelligence
3Stress or pressure
If the saturation current is reduced for hot operation, then mechanical stresses are reduced, but the actuator cannot provide sufficient torque during cold operation
Solution Approach 1:
The control unit changes the saturation current parameter based on temperature measurements. During cold operation, the saturation current is set to a higher value to ensure sufficient torque is available to overcome the high lubricant viscosity. During hot operation, the saturation current is reduced to limit mechanical stresses. This parameter adaptation resolves the contradiction by allowing high current when needed for torque and low current when needed for stress reduction
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
This approach prevents mechanical stress and damage by adjusting current saturation according to temperature, allowing for efficient operation across a wide temperature range without the need for oversized components, thus reducing mass and volume while protecting the actuator and its components.
Implementation Method 1
an electric motor (4) to selectively apply a force to friction members (5) of the brake and thus generate a braking torque
Implementation Method 2
The mechanical transmission of braking EMAs contains a lubricant whose physical characteristics vary greatly depending on the temperature, so that braking EMAs have operating characteristics that are highly dependent on the operating temperature. Typically, the lubricant has a high cold viscosity reducing the mechanical performance of the actuator.
Data Source
Figure 1~2b
Figure 3~4
AI summary
The invention relates to a method for supplying electrical current to an electromechanical braking actuator (1) equipping an aircraft wheel brake, in which the supply current (I) provided to the electromechanical braking actuator is saturated to a saturation value (Isat) to limit the current consumed by the electromechanical braking actuator and thus limit the forces developed by the actuator. The method comprises the step of determining the saturation value (Isat) as a function of an internal temperature (T) of the electromechanical braking actuator during its operation.