Hydraulic Cylinder Magnet Positioning for Stable Sensor Distance
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Solution Overview
Problem
Existing fluid pressure cylinders face challenges in adjusting the distance between magnetic sensors and magnets, leading to inconsistent magnetic force and increased costs due to unnecessary magnet size and fixed sensor positions.
Innovation Solution
A fluid pressure cylinder design with a rotatable piston unit and a movable member holding a magnet, allowing the magnet to be positioned at required points, enabling adjustable magnetic force and reduced weight and cost through efficient part usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ring-shaped magnet is attached to the entire circumference of the piston, then the position detection is reliable, but the weight and cost increase due to excessive magnet material
Solution Approach 1:
The ring-shaped magnet is divided into multiple independent non-ring-shaped magnets distributed around the piston circumference. Each magnet is held by a separate magnet holding portion on the movable member, allowing selective positioning rather than continuous circumferential coverage, thus reducing material usage while maintaining detection reliability.
Solution Approach 2:
Instead of uniform magnet distribution around the entire circumference, magnets are placed only at specific local positions where detection is required. The movable member's rotatable magnet holding portions position magnets locally according to the magnetic sensor's location, eliminating unnecessary magnet material in regions where detection is not needed.
2Ease of manufacture
If magnetic sensors are attached at fixed positions outside the cylinder tube, then the sensor mounting is simple, but the distance between sensors and magnets cannot be adjusted leading to inconsistent magnetic force
Solution Approach 1:
The magnet holding portions on the movable member are made rotatable relative to the piston body, allowing dynamic adjustment of magnet positions in the circumferential direction. This enables the distance between magnets and fixed-position sensors to be optimized for consistent magnetic force, while the fixed sensor mounting outside the cylinder tube maintains manufacturing simplicity.
Solution Approach 2:
The movable member with rotatable magnet holding portions is pre-installed on the piston body before final assembly. This allows the magnet positions to be adjusted and fixed in advance to achieve the optimal distance from the fixed sensors, ensuring consistent magnetic force without requiring complex sensor positioning during assembly.
3Weight of moving object
If non-ring-shaped magnets are used at certain points on the piston, then the weight and cost are reduced, but the distance between magnets and sensors changes when the piston rod rotates
Solution Approach 1:
The magnet holding portions are designed to be rotatable on the movable member, allowing the non-ring-shaped magnets to be dynamically repositioned in the circumferential direction. When the piston rod rotates, the magnets can be adjusted to maintain their optimal distance from the fixed sensors, preserving position detection reliability while using minimal magnet material.
Solution Approach 2:
The movable member serves multiple functions: it holds the non-ring-shaped magnets, provides rotatable adjustment capability, and maintains consistent magnet-sensor distance during piston rod rotation. This multi-functional design allows non-ring-shaped magnets to be used effectively without compromising detection reliability.
4Adaptability or versatility
If a ring-shaped magnet is used, then various sensor sensitivities are supported, but the product cost increases due to excessive magnet material
Solution Approach 1:
The ring-shaped magnet is segmented into multiple independent non-ring-shaped magnets that can be selectively positioned. This segmentation allows the system to use minimal magnet material while still supporting various sensor sensitivities by adjusting the number, position, and strength of individual magnets according to the specific sensor's requirements.
Solution Approach 2:
Instead of using a fixed ring-shaped magnet, the system allows adjustment of magnet parameters (number, position, strength) through the rotatable magnet holding portions. This enables optimization of magnet configuration for different sensor sensitivities, reducing the total amount of magnet material needed while maintaining versatility across different sensor types.
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 design allows for adjustable magnetic force and reduced product weight and cost, supporting various sensor sensitivities while maintaining consistent sensor-magnet distance during piston rod rotation.
Implementation Method 1
a magnet (46) held by the magnet holding portion (58) and disposed in the piston body (40) partially in a circumferential direction of the piston body (40)
Data Source
AI summary
A hydraulic cylinder (10) comprises a cylinder tube (12) having a circular slide hole (13), a piston unit (18), and a piston rod (20). The piston unit (18) has a circular piston body (40), packing (42) that is installed on the outer circumferential portion of the piston body (40), a movable member (44) that is mounted to the outer circumferential portion of the piston body (40) so as to be able to rotate relative to the piston body (40), and a magnet (46) that is held by a magnet holding unit (58) of the movable member (44). Relative rotation of the movable member (44) with respect to the cylinder tube (12) is regulated.