Push-Pull Solenoid Friction Guide for Plunger Return Control
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Solution Overview
Problem
Push-pull solenoids without a recovery mechanism suffer from excessive plunger recovery and dislodgment, leading to shock-like contact and vibration when interacting with objects, due to the lack of control over the plunger's return position and increased axial length when a recovery spring is used.
Innovation Solution
Incorporating a guide member with a friction guide surface that restricts axial sliding of the plunger, providing a controlled friction force to prevent over-recovery and dislodgment, and ensuring precise positioning of the plunger at its initial position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a recovery spring is added to prevent excessive plunger recovery, then the plunger positioning precision is improved, but the axial length of the solenoid increases and the stroke becomes shorter
Solution Approach 1:
The invention extracts and eliminates the recovery spring from the solenoid structure. Instead of using a spring mechanism, the plunger is retained through magnetic attraction force between the coil and plunger, which allows the plunger to be held at the retracted position without requiring additional axial space for a spring mechanism.
Solution Approach 2:
The invention replaces the mechanical spring-based recovery mechanism with a magnetic field-based retention system. The coil generates magnetic attraction force that substitutes for the mechanical spring force, enabling the plunger to be held in position without mechanical contact or spring compression, thereby reducing axial length.
2Length of moving object
If no recovery mechanism is provided to reduce axial length, then the stroke is maximized, but the plunger experiences excessive recovery and dislodgment causing shock-like contact
Solution Approach 1:
The invention employs dynamic control of the magnetic field through the coil to regulate plunger movement. By controlling the coil energization, the magnetic attraction force dynamically adjusts to guide the plunger smoothly to the retracted position and hold it there, preventing excessive recovery and shock-like contact while maintaining a compact structure.
Solution Approach 2:
The magnetic attraction system provides inherent feedback control where the coil's magnetic field responds to the plunger position. When the plunger approaches the retracted position, the increasing magnetic attraction force automatically slows and stops the plunger, preventing over-travel and shock contact without requiring separate mechanical feedback mechanisms.
3Manufacturing precision
If a recovery spring is used to control plunger return, then the plunger positioning is improved, but the device complexity increases
Solution Approach 1:
The coil serves multiple functions: it generates the magnetic attraction force to move the plunger during actuation, and simultaneously functions as the retention mechanism to hold the plunger at the retracted position. This multi-functionality eliminates the need for a separate recovery spring, reducing structural complexity while maintaining positioning precision.
Solution Approach 2:
The invention merges the actuation and retention functions into a single magnetic field system generated by the coil. Instead of having separate mechanisms for pushing the plunger and for holding it, the magnetic attraction force combines both functions, simplifying the overall structure.
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 solution effectively suppresses shock-like contact and vibration, maintains precise control over the plunger's movement, and prevents excessive recovery or dislodgment, ensuring consistent operation without the need for a recovery spring.
Implementation Method 1
a coil that generates magnetic attraction for causing the plunger to slide in the axial direction from a return position set apart from the case end surface in a withdrawing direction approaching the case end surface
Implementation Method 2
the guide member being provided with a friction guide surface that guides the plunger in the axial direction in association with prescribed friction
Data Source
AI summary
A push-pull solenoid is provided with a cylindrical guide member that is fixed to a case. A circular outer peripheral surface of a plunger is in contact with a friction guide surface formed on a circular inner peripheral surface of the guide member, and slides along the friction guide surface. Frictional force due to contact with the friction guide surface is always acting on the plunger, so it is possible to suppress impact-like contact of the plunger with an object to be manipulated during suctioning, and vibration and noise caused thereby. Moreover, over-recovery and falling-out of the plunger after suction is released can also be prevented.