Parallel Constant Force Spring Actuator for Handheld Micrometers
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Solution Overview
Problem
Existing handheld micrometers with constant force spring actuators are bulky and have a short lifetime, and when compacted, they often fail to provide sufficient force to drive the spindle effectively towards the anvil.
Innovation Solution
A compact micrometer design incorporating at least two parallel constant force spring coils attached between the spindle and the frame, providing a greater force and extended life, with each coil capable of exerting at least 0.05 N, and designed to fit within a specific size and material constraint to ensure ergonomic and convenient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a constant force spring actuator is made compact, then the device size is reduced, but the force provided by the spring decreases
Solution Approach 1:
The patent divides the single spring system into multiple parallel spring coils (at least two, preferably three or more). Each coil is attached between the spindle and frame, and they work in parallel to collectively provide the required constant force. This segmentation allows the actuator to remain compact while maintaining sufficient force output through the combined effect of multiple springs.
2Volume of moving object
If a constant force spring actuator is made compact, then the device size is reduced, but the lifetime of the spring coils decreases
Solution Approach 1:
By dividing the load across multiple parallel spring coils, each individual coil experiences reduced stress and wear compared to a single spring system. This segmentation of the mechanical load extends the operational lifetime of each spring coil while maintaining the same overall force output, allowing the actuator to remain compact without sacrificing durability.
Solution Approach 2:
The patent specifies that each spring coil provides a force of at least 0.05 N, and the material thickness is controlled to be at most 0.4 mm. These parameter specifications optimize the balance between compact size, sufficient force, and extended lifetime by carefully controlling the dimensions and mechanical properties of the spring coils.
3Volume of moving object
If the spring coils are made thinner to reduce size, then the actuator becomes more compact, but the force capacity and lifetime are reduced
Solution Approach 1:
The patent specifies that each spring coil comprises material which is at most 0.4 mm thick, optimizing the balance between compactness and force capacity. By controlling the material thickness parameter and specifying that each coil provides at least 0.05 N of force, the design achieves the required force output while maintaining a compact form factor.
Solution Approach 2:
Multiple thinner spring coils work in parallel to collectively provide the required total force. This allows each individual coil to be made thinner (at most 0.4 mm) for compactness, while the combined force of multiple coils maintains or exceeds the required force capacity.
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 micrometer achieves a compact, ergonomic, and convenient design with increased force and extended spring coil life, allowing for efficient and precise spindle movement towards the anvil with minimal user effort.
Implementation Method 1
a constant force spring actuator comprising at least two constant force spring coils extending in parallel toward the spindle and attached between the spindle and the frame such that the sum of their forces drives the spindle toward the anvil with a constant force
Data Source
AI summary
A micrometer, including a constant force drive spring actuator configuration, is disclosed which comprises a frame, an anvil, a spindle, a linear displacement sensor that senses a displacement of the spindle, and an actuator including a button which is configured to move the spindle toward or away from the anvil. The spindle drive is attached to a constant force spring actuator comprising at least one constant force spring coil extending toward the spindle and attached between the spindle and the frame such that the sum of their forces drives the spindle toward the anvil with an approximately constant force. In some embodiments, the constant force spring actuator comprises at least two parallel constant force spring coils, extending in parallel toward the spindle. The constant force spring may be made more compact, exert a greater force, and have an extended life relative to known configurations.