Neutral Return Shaft Mechanism With Nested Spring Housing
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Solution Overview
Problem
There is a need for a compact neutral return mechanism that effectively returns an operation member, such as a lever or pedal, to a neutral position after it has been operated to control a hydraulic actuator, while efficiently managing the movement and load applied by a neutral return spring.
Innovation Solution
The proposed solution involves a neutral return mechanism with an interlocking shaft that is pushed and pulled axially in conjunction with the operation member's movement, supported by a housing member that allows axial movement and accommodates a neutral return spring. This mechanism includes a detent mechanism to hold the interlocking shaft in an operated position outside the range of automatic return by the spring, utilizing a coil spring and specific spring receiving members to manage the movement and load efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a neutral return spring is used to return the interlocking shaft to the initial position, then the operation member can be returned to the neutral position, but the mechanism becomes larger in size
Solution Approach 1:
The neutral return spring is nested within the housing member, with the spring accommodation portion providing internal space for the spring. This allows the spring to be contained within the existing structural boundaries rather than requiring additional external space, thereby achieving compact integration of the return mechanism.
Solution Approach 2:
The spring accommodation portion is positioned at a location that utilizes three-dimensional space efficiently within the housing member. By arranging the spring in an axial direction and positioning the supported portion between the spring accommodation portion and the protrusion opening, the design optimizes spatial utilization in multiple dimensions rather than simply extending in one direction.
2Adaptability or versatility
If the interlocking shaft is made movable in the axial direction to operate the control valve, then the control function is achieved, but the structure becomes more complex
Solution Approach 1:
The interlocking shaft serves multiple functions: it is pushed and pulled in the axial direction to operate the control valve, it is supported by the housing member to enable movement, and it interacts with the neutral return spring for automatic return. This multi-functionality reduces the need for separate components for each function, thereby simplifying the overall structure.
Solution Approach 2:
The supported portion acts as an intermediary element between the interlocking shaft and the bracket member, providing a connection point that enables the shaft's axial movement while maintaining structural support. This intermediary structure simplifies the connection mechanism compared to direct rigid mounting.
3Volume of moving object
If the supported portion is positioned between the spring accommodation portion and the protrusion opening, then the neutral return spring can be effectively accommodated, but the housing member design becomes more complex
Solution Approach 1:
The housing member is segmented into distinct functional portions: the spring accommodation portion for housing the neutral return spring, the supported portion for supporting the interlocking shaft, and the protrusion opening for shaft protrusion. This segmentation allows each portion to be optimized for its specific function while maintaining an integrated overall structure.
Solution Approach 2:
Different portions of the housing member have different structural characteristics tailored to their specific functions. The spring accommodation portion is designed to accommodate the spring, the supported portion provides shaft support, and the protrusion opening allows shaft protrusion. This local optimization of structural properties achieves effective spring accommodation without requiring the entire housing to be overly complex.
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 a compact and efficient return of the operation member to its neutral position, effectively managing the movement and load applied by the neutral return spring, while maintaining the operation member outside the range of automatic return strokes, thus ensuring reliable operation and compact design.
Implementation Method 1
a neutral return spring (33) to return the interlocking shaft (31) from a post-movement position (P5, P6) to an initial position (P4)
Implementation Method 2
The neutral return spring (33) including a coil spring
Data Source
AI summary
A neutral return mechanism includes an interlocking shaft to be pushed and pulled in an axial direction in conjunction with a swinging operation of an operation member; a housing member to support the interlocking shaft such that the interlocking shaft is movable in the axial direction and accommodate the interlocking shaft such that one of opposite end portions thereof protrudes; a neutral return spring to return the interlocking shaft from a post-movement position to an initial position, the neutral return spring being accommodated in the housing member such that the neutral return spring extends in the axial direction of the interlocking shaft, wherein the housing member includes a supported portion between a spring accommodation portion in which the neutral return spring is accommodated and a protrusion opening through which the interlocking shaft protrudes, the supported portion being supported at a bracket member.