Multi-Start Thread Sensor Lock for Process Vessels
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Solution Overview
Problem
Existing manually operable sensor locks for process containers require excessive labor and time to move sensor units between measurement and maintenance positions due to conventional single-start threads, which are inefficient under high process pressures and pose a risk of operator injury.
Innovation Solution
Designing a spindle-like displacement drive with a multi-start thread and minimizing friction through the use of low-friction materials like PTFE, eliminating the need for self-locking threads and relying on sealing and bearing friction for locking, allowing for easier and faster operation of the sensor unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single-start thread is used in the spindle drive, then the transmission ratio is high enough to overcome process pressure forces, but the number of turns required to move the sensor unit becomes excessively large (12-60 turns)
Solution Approach 1:
The patent changes the thread configuration from single-start to multi-start (2-12 starts), which fundamentally alters the relationship between rotational movement and axial displacement. This parameter change reduces the number of turns required while maintaining adequate mechanical advantage through optimized pitch angles (10-30 degrees) and thread geometry.
2Productivity
If a multi-start thread with high pitch angle is used, then the number of turns is reduced, but the actuating force required to overcome thread friction increases
Solution Approach 1:
The patent optimizes the pitch angle parameter to a specific range (10-30 degrees) that balances two competing requirements: achieving sufficient axial displacement per turn (productivity) while maintaining acceptable friction characteristics. This parameter optimization resolves the contradiction by finding the optimal middle ground rather than maximizing either extreme.
Solution Approach 2:
The patent replaces reliance on thread self-locking with a friction-based locking mechanism using sealing elements. This substitution allows the use of multi-start threads with higher pitch angles without requiring excessive preloading forces, as the locking function is performed by the sealing friction rather than thread friction alone.
3Reliability
If self-locking threads are used to prevent reverse movement under pressure, then the thread pitch is limited to small values (2-5 mm), but the operation becomes laborious and time-consuming
Solution Approach 1:
The patent substitutes the traditional thread-based self-locking mechanism with a sealing-friction-based locking system. The sealing elements create sufficient friction to prevent reverse movement of the sensor unit under process pressure, eliminating the need for conservative self-locking thread designs. This allows the use of multi-start threads with larger pitch values, significantly reducing operation time.
Solution Approach 2:
The patent introduces sealing elements as intermediary components between the threaded piston and the drive mechanism. These sealing elements serve dual functions: preventing process fluid leakage and providing the friction necessary for self-locking. This intermediary approach decouples the locking function from the thread geometry, allowing optimization of thread pitch for faster operation.
4Device complexity
If conventional spindle drives with single-start threads are used, then the system is simple in design, but the operational complexity and time required increase significantly
Solution Approach 1:
The patent modifies the thread configuration parameter from single-start to multi-start while maintaining the overall simplicity of the spindle drive design. The increased complexity in thread geometry is offset by the elimination of complex self-locking mechanisms and the reduction in operational steps, resulting in a net improvement in ease of operation despite slightly increased manufacturing complexity.
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
Significantly reduces the number of turns required to move the sensor unit, making the operation smoother and safer, with lower actuating forces needed even at high process pressures, as the friction torque is independent of the thread pitch and process pressure.
Implementation Method 1
a spindle-like displacement drive (24) for the sensor unit (8) in the form of a threaded piston (27) which is displaceable in the axial direction in a threaded sleeve (25)
Implementation Method 2
the necessary self-locking of the entire drive unit can be generated by the friction within the seals and bearings of the threaded sleeve
Implementation Method 3
minimizing friction through the use of low-friction materials like PTFE
Data Source
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AI summary
A manually operated sensor lock for the interchangeable installation of measuring sensors (13) in process vessels (5) comprises: - a base body (2) that can be connected to a process vessel (5), - a sensor unit (8) slidably mounted in the base body (2), which preferably consists of a dip tube (9) with a measuring sensor (13) held therein and which can be moved between a measuring position and a maintenance position, - a spindle-like displacement drive (24) for the sensor unit (8), comprising an outer, manually rotatable threaded sleeve (25) and a threaded piston (27) seated therein and engaging with it, on which the sensor unit (8) is arranged, and - an internal thread (30) on the threaded sleeve (25) engaging with the threaded piston (27), which is designed as a multi-start thread.