Actuator Arrangement with Worm Gear and Encoder
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Solution Overview
Problem
Actuators in HVAC systems, particularly in VAV systems and fume hoods, face inefficiencies due to poor position control, leading to overshoot or undershoot, which can result in energy wastage and safety hazards from inaccurate damper control.
Innovation Solution
The use of a worm gear in the actuator's gear train combined with direct positional feedback, where position encoding indicia on the output gear are detected by an encoding detector, allowing for precise control and feedback to the control circuit to drive the motor accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a VAV system uses basic actuator control without precise positional feedback, then the system is simpler and cheaper, but the damper position control accuracy deteriorates leading to overshoot or undershoot
Solution Approach 1:
The patent implements direct positional feedback by mounting an encoder detector directly on the output gear of the actuator, which measures the actual position of the output shaft and feeds this information back to the control circuit. This closed-loop feedback mechanism enables precise position control by continuously comparing the actual position with the desired position and adjusting the motor output accordingly, thereby eliminating overshoot and undershoot issues while maintaining reasonable system complexity.
Solution Approach 2:
The patent replaces indirect mechanical position sensing methods with direct electronic encoding detection. Instead of using mechanical linkages or indirect sensors to determine position, the encoder detector directly reads position encoding indicia on the output gear, providing accurate positional information electronically. This substitution improves measurement precision while reducing mechanical complexity in the feedback path.
2Measurement precision
If the actuator uses a worm gear with direct positional feedback, then position control accuracy improves, but the device complexity increases due to additional components
Solution Approach 1:
The patent merges the position encoding indicia directly onto the output gear that is already part of the worm gear train, rather than adding a separate position sensing mechanism. The encoder detector is integrated into the actuator housing and directly reads the encoding on the output gear. This merging approach allows the same mechanical component (output gear) to serve both mechanical transmission and position encoding functions, improving measurement precision without proportionally increasing device complexity.
3Loss of energy
If the actuator implements tight position control with encoding detection, then energy efficiency improves through reduced overshoot, but manufacturing complexity increases
Solution Approach 1:
The output gear serves multiple functions: it transmits mechanical motion from the worm gear, provides the mechanical connection to the output shaft, and simultaneously carries the position encoding indicia for the encoder detector. This multi-functionality reduces the need for separate components, thereby improving energy efficiency through tight control while limiting the increase in manufacturing complexity.
4Stability of the object's composition
If the actuator uses dampening to reduce overshoot, then stability improves, but the response time deteriorates
Solution Approach 1:
The direct positional feedback from the encoder detector enables the control circuit to implement active damping through control algorithms rather than passive mechanical dampening. The system can detect position errors in real-time and adjust motor torque accordingly, providing stability while maintaining fast response times. This electronic feedback-based damping is superior to mechanical dampening because it can respond instantaneously to position deviations without introducing mechanical friction or inertia delays.
Data Source
AI summary
An actuator arrangement having a rotational output includes a power input, a motor, at least an intermediate gear, a solenoid and an output. The power input connects to a source of electrical power. The motor has an output shaft including a worm gear. The motor is operably connected to the power input. The motor and output shaft are rotatably connected to a housing of the actuator. The output gear generates a rotational output at an axis thereof, and is operably coupled to be driven by the at least one intermediate gear. The solenoid is operably connected to the power input, and includes a piston member. The piston member has an actuated and a non-actuated position. The piston member in the actuated position urges the worm gear and the at least one intermediate gear into meshing connection.