Polypropylene Recliner Handle Without Metal Insert
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Solution Overview
Problem
Prior recliner chair handles have high manufacturing costs due to molded metal inserts and inadequate locking mechanisms, leading to potential loosening and rotation of the drive rod.
Innovation Solution
A handle design without a molded metal insert, using a threaded fastener that self-taps into the drive rod and engages with a slot to secure the handle, providing a positive coupling and preventing rotation, while made of flexible polypropylene to withstand loads without breaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal insert is molded within the handle, then the drive rod can be secured to the handle, but manufacturing costs increase
Solution Approach 1:
The patent removes the metal insert component entirely from the handle assembly. Instead of molding a metal insert within the handle, the invention uses a separate threaded fastener that engages directly with the drive rod, eliminating the need for the complex metal insert while maintaining the drive rod retention function.
Solution Approach 2:
The patent replaces the expensive metal insert with a simpler, more cost-effective threaded fastener. This fastener is designed to be inserted through the handle and engage with the drive rod, providing the necessary retention at a lower manufacturing cost.
2Ease of operation
If a set screw is used to retain the drive rod, then the handle can be assembled, but the drive rod can loosen and rotate during use
Solution Approach 1:
The patent divides the fastening function into two distinct components: a threaded fastener that provides retention and a separate locking mechanism (such as a lock washer or nyloc nut) that prevents loosening and rotation. This segmentation allows each component to specialize in its function, improving overall reliability.
Solution Approach 2:
The patent employs a composite fastening system combining different material properties and mechanical features. The threaded fastener may incorporate locking features such as nylon inserts (nyloc nuts) or lock washers that combine friction, deformation, and geometric locking to prevent both loosening and rotation during use.
3Strength
If the handle is made of rigid material, then it can provide structural support, but it may break under extended use loads
Solution Approach 1:
The patent changes the material parameter from rigid to flexible, selecting a flexible polymer material for the handle. This material can elastically deform under load and return to its original shape, preventing the catastrophic failure that occurs with rigid materials under repeated stress cycles.
Data Source
AI summary
A detachable operator assembly for a recliner chair including a handle, a drive rod and a threaded fastener. The handle is configured to operably connect with the drive rod without requiring a metal insert or reinforcement. The threaded fastener is inserted into a counterbore formed in the handle such that the shank freely passes through the handle and threadingly engages the drive rod. The shank extends through the drive rod to threadingly engage the handle. The operator assembly is configured so that the fastener fails before the plastic handle fails, and more specifically, so the fastener breaks between the fastener head and the drive rod, thereby allowing easy removal of the broken fastener without disassembly of the drive rod from the reclining chair.