Coded Switch Position Sensing for Hydraulic Drives in Extreme Conditions
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Solution Overview
Problem
Existing position detection systems for hydraulic and electrohydraulic drives, such as potentiometers, are prone to interference and fail in extreme conditions like very low temperatures and risk of explosion, leading to inaccurate control and adjustment of drives like doors and ball valves.
Innovation Solution
A device using a switching unit with multiple adjacent switches and an actuation member with corresponding switch triggers, where the switch triggers are arranged to provide a clear combination of switch positions for each relative position, stored in a control module for precise position detection without continuous electric sensors, ensuring functional safety even in extreme conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If potentiometers are used for continuous position detection, then measurement precision is improved, but reliability deteriorates under extreme conditions
Solution Approach 1:
The continuous position detection range is segmented into multiple discrete detection zones, each marked by a switch trigger. The actuation member divides the rotation path into segments, with each segment corresponding to a specific switch activation. This segmentation allows the system to maintain reliability through discrete mechanical switches while achieving sufficient precision through the coded sequence of activations.
Solution Approach 2:
The patent replaces the electrical potentiometer system with a mechanical actuation member that directly triggers switches through physical contact. This mechanical substitution eliminates the vulnerabilities of electrical sensors in extreme conditions (temperature, explosion risk) while maintaining position detection capability through the mechanical sequence of switch activations.
2Reliability
If end position switches are used to detect only end positions, then reliability is improved, but measurement precision deteriorates
Solution Approach 1:
The detection system is segmented into multiple switches arranged along the travel path, with each switch triggered at a specific position segment. This segmentation enables both reliable discrete detection and precise relative position measurement through the sequence and combination of activated switches, resolving the contradiction between reliability and precision.
Solution Approach 2:
The system transitions from detecting only end positions (0D) to detecting multiple discrete positions along the travel path (1D). By arranging switches spatially along the movement trajectory and using the actuation member to activate them in sequence, the system gains positional resolution while maintaining the reliability of discrete mechanical switching.
3Measurement precision
If electric potentiometers are used for position detection, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the continuous sensing function from the complex electrical potentiometer system and replaces it with a simpler mechanical switch triggering mechanism. By removing the electrical sensor components and using only mechanical triggers and switches, the system achieves sufficient precision through discrete position coding while significantly reducing device complexity.
Solution Approach 2:
The system uses simple, inexpensive mechanical switches and a straightforward actuation member instead of complex, expensive electrical potentiometers. These simpler components are more reliable in extreme conditions and easier to implement, reducing both device complexity and cost while maintaining adequate measurement precision through the coded switch sequence.
Data Source
AI summary
A device for sensing a rotary or linear position of moving parts of drives, in which a moving part performs a rotary movement or a linear positioning movement with respect to a stationary part, has a switch unit comprising switches arranged next to one another in a row and is arranged on the stationary part, and having an actuating element for actuating the switches based on the relative position of the moving part, the actuating element having switch triggers corresponding to the number of switches and each being assigned to the respective switches, such that there is a respectively defined unique combination of positions of the switches for each relative position between the moving part and the stationary part, and a control module having an analysis unit for storing coding for the different switch positions in relation to the relative position of the moving part of the drive.