Actuator with Variable Lever Arm Spring for Motor Protection
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Solution Overview
Problem
Existing actuators for heating, ventilating, and cooling systems face issues with reliability, durability, and cost, particularly when dealing with peak-load torque and the need for quick shutdown to prevent motor damage, which is often achieved with expensive components.
Innovation Solution
The actuator design incorporates a gear unit with a flexible spring and a mechanical arrangement that reduces counteraction force as it moves out of the idle state, using a snap-in cam and sensor elements to prevent the actuator from restarting, allowing a smaller and cheaper motor to handle tasks effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard flexible spring is used to hold the gear part in center position, then the actuator can return to idle state, but the motor may splutter and restart causing damage
Solution Approach 1:
The spring characteristic is changed from linear to non-linear by varying the lever arm length during rotation. The distance between spring application point and rotation axis increases with rotation angle, causing the spring force effect to decrease as the gear part moves away from center position. This dynamic modification prevents motor spluttering while maintaining reliable return to idle state.
Solution Approach 2:
The effective lever arm length of the spring is changed as a function of rotation angle. By making the lever arm length variable rather than constant, the spring's counteracting moment is reduced as the gear part rotates away from center, preventing the motor from encountering excessive reverse torque that would cause spluttering.
2Reliability
If a torsion spring with high counteraction force is used to prevent unlocking, then the motor cannot be unlocked when idle, but the motor size must be increased to handle the peak torque
Solution Approach 1:
The spring's effective lever arm is dynamically adjusted during rotation to provide high initial holding torque when the gear part is at center position (preventing unwanted unlocking) while progressively reducing the counteracting moment as rotation progresses, allowing the motor to overcome the spring force without requiring excessive peak torque capacity.
Solution Approach 2:
The spring characteristic is modified by varying the distance from the spring application point to the rotation axis. This creates a non-linear torque characteristic where the spring provides maximum holding force at idle position but reduces its counteraction as the gear part rotates, enabling reliable unlocking prevention without oversizing the motor.
3Object-affected harmful factors
If expensive electronic systems are used to prevent motor spluttering, then motor damage is avoided, but the actuator cost increases significantly
Solution Approach 1:
The patent replaces expensive electronic control systems with a simple mechanical arrangement involving a flexible spring and variable lever arm. This mechanical solution is cheaper to manufacture while effectively preventing motor spluttering through the non-linear spring characteristic that reduces counteraction force during rotation.
Solution Approach 2:
The patent substitutes electronic control mechanisms with a purely mechanical solution. The variable lever arm flexible spring mechanism automatically adjusts the spring force effect during rotation, eliminating the need for electronic sensors, controllers, or feedback systems to prevent motor spluttering.
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 design ensures reliable operation and cost reduction by preventing motor spluttering and damage, allowing a smaller motor to manage tasks with reduced counteraction force, enhancing durability and efficiency.
Implementation Method 1
The gear unit (10) is fitted with a flexible spring (4) acting on two gear parts (1, 14) to hold them in an idle state
Implementation Method 2
the first gear part (1) is at least fitted with a cam plate (5), the second gear part (14) is at least fitted with a sensor element (7) for the cam plate (5)
Data Source
AI summary
At least a motor, a gear unit and an adjustment connection form an actuator. The gear unit is fitted with at least two mutually movable gear parts, as well as a spring acting on two of these that counteracts their movement out of an idle state. The gear unit is designed such that when an adjustment connection is blocked the motor moves the gear parts out of the idle state during operation to an operating point. In addition, the gear unit is designed such that during the movement out of the idle state it reduces the extent to which the movement is counteracted from a particular point upstream of the operating point.