Actuator Motor Speed Limiting for Overheating Prevention
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Solution Overview
Problem
Electrically powered actuators, such as electro-hydrostatic actuators, are prone to overheating and damage due to sustained fluid circulation through pressure relief valves, leading to excessive force and current demands that exceed the electronics' capacity, causing potential failure.
Innovation Solution
Incorporating monitoring means to detect the opening of pressure relief valves and calculating an auxiliary setpoint value to limit the electric motor's speed to a predetermined maximum, preventing overheating by applying this value instead of the original setpoint value when the valve opens, thus reducing the hydraulic pump's action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the electric motor drives the hydraulic pump at high speed to generate sufficient hydraulic power, then the actuator can produce the necessary force, but the pressure relief valve opens causing fluid overheating and damage to the actuator
Solution Approach 1:
The control system performs preliminary action by detecting the opening of the pressure relief valve and responding before severe overheating occurs. The monitoring means detects valve opening and the control means immediately limits motor speed to prevent the harmful thermal effects from developing further
Solution Approach 2:
The system implements feedback control by using monitoring means to detect the state of the pressure relief valve and feeding this information back to the control means, which then adjusts the motor speed accordingly. This closed-loop feedback prevents the contradiction from escalating by continuously adapting the motor speed based on the actual hydraulic system state
2Strength
If the pressure relief valve opens to limit the force generated by the actuator, then the structure is protected from excessive forces, but the electric motor must supply high torque causing overheating of control electronics
Solution Approach 1:
The control system takes preliminary action by detecting pressure relief valve opening and preemptively limiting motor speed before the electronics are damaged. This prevents the high torque condition from persisting and causing thermal damage to the control electronics
Solution Approach 2:
The system provides beforehand cushioning by preparing the control response in advance - when the pressure relief valve opens, the control means immediately limits motor speed to reduce torque demands on the electronics, cushioning them against thermal damage before it occurs
3Speed
If the electric motor operates at maximum speed to respond quickly to control signals, then the actuator responds rapidly, but sustained operation causes fluid circulation through the pressure relief valve leading to actuator damage
Solution Approach 1:
The system applies dynamics by making the motor speed adaptive rather than fixed. The control means dynamically adjusts motor speed based on real-time detection of pressure relief valve state, allowing high speed when safe and limiting speed when the valve opens, thus maintaining reliability while preserving responsiveness when needed
Solution Approach 2:
The feedback mechanism continuously monitors the pressure relief valve state and adjusts motor speed accordingly. This feedback loop ensures the actuator operates reliably by preventing sustained high-speed operation that would cause fluid circulation through the relief valve and subsequent damage
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 solution effectively protects the actuator from overheating and damage by controlling the motor speed when the pressure relief valve opens, ensuring the actuator operates within safe parameters and preventing overheating, even when the pressure relief valve is activated.
Implementation Method 1
an electric motor (4), which drives a pump (5) in accordance with a setpoint value (10) received from said control module (2)
Implementation Method 2
a hydraulic pump, a pressure relief valve, a hydraulic block and a hydraulic cylinder
Implementation Method 3
at least one pressure relief valve to limit the force generated by the actuator, said pressure relief valve being opened automatically so as to perform its limitation function when the pressure difference between the two chambers reaches a predetermined value
Implementation Method 4
a hydraulic cylinder which comprises two chambers capable of being supplied by the pump and which generates the force of the actuator
Data Source
Figure 1~2
Figure 3~4
AI summary
- Electrically powered actuator and method for controlling such an actuator. - Said actuator (1) includes means (23) for limiting the speed of the electric motor (4) controlling the hydraulic pump (5) of the actuator (1), when a pressure relief valve (11) is opened.