Valve Bonnet Asymmetric Thread Locking Mechanism
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Solution Overview
Problem
Existing valves face difficulties in preventing rotation and locking of the bonnet within the body, especially when the bonnet is threaded and a sealing member is internal to the stem threads.
Innovation Solution
The valve design incorporates different thread pitches and directions on various components, including the body, stem, bonnet, and locking nut, which prevents the bonnet from rotating by ensuring that the thread configurations on the bonnet and body are mismatched, thereby locking the bonnet in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the bonnet is threaded into the body with standard threads, then the bonnet can be easily assembled and disassembled, but the bonnet may rotate within the body causing leakage or misalignment
Solution Approach 1:
The patent applies asymmetry by using different thread pitches on the inner and outer surfaces of the bonnet. The inner surface has threads with a first pitch that mate with the body, while the outer surface has threads with a second pitch that mate with the locking nut. This asymmetric thread configuration prevents the bonnet from rotating within the body during operation, while still allowing easy assembly and disassembly when needed.
2Reliability
If a locking mechanism is added to prevent bonnet rotation, then rotation prevention is improved, but the device complexity increases
Solution Approach 1:
The bonnet serves multiple functions: it connects to the body through threaded engagement, provides a mounting surface for the locking nut, and prevents rotation through its dual-thread configuration. The locking nut also serves dual purposes by securing the bonnet to the body and preventing rotation. This multi-functionality reduces the need for separate dedicated rotation-prevention components, thereby limiting the increase in device complexity.
3Reliability
If different thread pitches are used on the bonnet surfaces, then rotation prevention is achieved, but the manufacturing precision requirements increase
Solution Approach 1:
The bonnet is segmented into two distinct threaded surfaces with different pitch characteristics. The inner surface threads engage with the body while the outer surface threads engage with the locking nut. This segmentation allows each thread set to be optimized independently for its specific function, with the locking mechanism threads designed to prevent rotation while the body-connection threads are optimized for assembly. This independent optimization reduces the overall manufacturing precision burden compared to a single complex thread system.
Data Source
AI summary
The present invention provides a valve with different threads for preventing rotation of and locking a bonnet with the valve.