Fluid Pressure Cylinder Piston Position Detection
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Solution Overview
Problem
Conventional fluid pressure cylinders require a ring-shaped magnetic body around the piston to prevent rotational displacement, increasing manufacturing costs and weight due to the excess magnetic material needed for detection sensors.
Innovation Solution
A magnetic body is positioned on the piston to face detection sensors along the circumferential direction, with a guide rod restricting rotational displacement, eliminating the need for a ring-shaped magnetic body on the piston and reducing the amount of magnetic material used.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a ring-shaped magnetic body is provided around the piston to prevent rotational displacement, then the piston position can be detected by sensors, but the amount of magnetic material increases, leading to higher manufacturing costs and weight
Solution Approach 1:
The ring-shaped magnetic body is segmented into a plurality of discrete magnetic bodies arranged along the circumferential direction of the piston. This segmentation reduces the total amount of magnetic material needed while still providing sufficient magnetic field interaction with the detection sensors for accurate piston position detection.
Solution Approach 2:
Instead of uniformly distributing magnetic material around the entire circumference, magnetic bodies are strategically positioned at specific locations where they can effectively interact with the detection sensors. This local concentration of magnetic material optimizes detection capability while minimizing overall material usage.
2Stability of the object's composition
If a ring-shaped magnetic body is provided around the piston, then rotational displacement can be restricted, but the weight of the piston increases
Solution Approach 1:
The continuous ring-shaped magnetic body is divided into multiple discrete magnetic bodies spaced around the piston circumference. This segmentation maintains the rotational stability function while significantly reducing the total weight compared to a solid ring structure.
Solution Approach 2:
Instead of providing magnetic material around the entire circumference, a partial arrangement of magnetic bodies at specific angular positions is sufficient to prevent rotational displacement. This partial action achieves the stability requirement with minimal material and weight.
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
This configuration allows for reliable piston position detection by sensors while reducing manufacturing costs and weight by minimizing the amount of magnetic material required.
Implementation Method 1
the magnetic body is disposed at a position facing toward the detection sensor that is arranged along the circumferential surface of the cylinder tube
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
In a piston unit (18) of a fluid pressure cylinder (10), a plurality of magnets (122) are disposed through holes (120) provided in a ring body (100). The magnets (122) are disposed in facing relation to detection sensors (92) that are mounted on connecting rods (88), and are provided in the same quantity as the connecting rods (88). Further, a guide rod (124) extending from a head cover (14) to a rod cover (16) is inserted through the interior of the ring body (100). When the piston unit (18) is displaced along the cylinder tube (12), rotational displacement is restricted by the piston unit (18) being displaced along the guide rod (124), whereby the magnets (122) are retained so as to face toward the connecting rods (88) at all times. Therefore, the position of the piston unit (18) is detected by the detection sensors (92) through the magnets (122).