Spring Return Actuator Air Brake Speed Control
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Solution Overview
Problem
Existing electro-mechanical actuators for HVAC systems face issues with excessive spring return speed upon power loss, leading to potential damage and reduced efficiency due to the need for multiple gear trains and parasitic components.
Innovation Solution
A compact actuator design utilizing a single gear train that adjusts rotational speed of the air brake based on power source, with a magnetic slip clutch and solenoid to control the air brake's speed, preventing damage and maintaining efficiency during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring return mechanism is used to position the valving member in a fail safe position upon power loss, then the valve can be reliably positioned in an emergency, but the spring return speed becomes excessive and may destroy the gear train due to impact
Solution Approach 1:
An air brake mechanism is introduced as an intermediary between the spring return mechanism and the gear train. The air brake includes a paddle wheel that interacts with air to provide controlled resistance, mediating the spring's energy release to prevent excessive speed while maintaining reliable fail-safe positioning.
Solution Approach 2:
The patent employs an air brake system that utilizes pneumatic principles. The paddle wheel rotates within air, creating aerodynamic drag that provides speed control during spring return. This pneumatic braking mechanism controls the release of spring energy without requiring additional mechanical components.
2Object-affected harmful factors
If two separate gear trains are used (one for normal operation and one for spring return), then the spring return speed can be controlled, but the device complexity and cost increase
Solution Approach 1:
A single gear train is designed to serve dual functions: driving the output member during normal motor operation and facilitating controlled spring return. The same gear train components are used in both operational modes, eliminating the need for separate gear trains and reducing overall system complexity.
Solution Approach 2:
The patent merges the normal operation drive path and the spring return drive path into a single integrated gear train system. By combining these functions into one gear train, the design reduces the number of components while maintaining the ability to control spring return speed through the air brake mechanism.
3Object-affected harmful factors
If a parasitic gear train is used to drive the air brake, then the spring return speed is controlled, but the paddle provides unnecessary braking force during normal motor operation reducing efficiency
Solution Approach 1:
The system dynamically adapts the air brake's engagement based on operational mode. During normal motor operation, the air brake is disengaged or provides minimal resistance. During spring return, the air brake is actively engaged to provide speed control. This dynamic behavior eliminates unnecessary energy loss during motor operation while maintaining spring return control.
Solution Approach 2:
The air brake system automatically adjusts its braking action based on the operational state. The same mechanism that controls spring return speed does not interfere with normal motor operation, as the system self-regulates the level of braking force applied based on whether the motor or spring is the active drive source.
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 actuator effectively controls the spring return speed without damaging the gear train or reducing motor efficiency, ensuring reliable operation and reduced component costs by eliminating the need for separate gear trains.
Implementation Method 1
employing a magnetic slip clutch and bi-stable solenoid to control the gear train operation
Implementation Method 2
employing a magnetic slip clutch and bi-stable solenoid to control the gear train operation
Implementation Method 3
utilizing a single gear train that adjusts rotational speed of the air brake
Data Source
AI summary
An actuator including a motor, clutch, gear train, solenoid, clock spring, and air brake is provided. The motor is configured to drive a control valve. The clutch is operably coupled to the motor and configured to prevent the motor from transferring more than a predetermined amount of torque. The gear train is operably coupled to the clutch and configured to receive the predetermined amount of torque from the motor. The solenoid is operably coupled to the gear train and configured to disengage one of the gears in the gear train from adjacent gears. The clock spring is operably coupled to another of the gears in the gear train, configured to store mechanical energy supplied by the motor, and configured to drive the control valve. The air brake is operably coupled to the gear train and configured to dissipate a portion of the mechanical energy released by the clock spring.