Fluid Pressure Control Device Piston Spherical Protrusion
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Solution Overview
Problem
The existing fluid pressure control devices for hydraulic operating machines face inefficiencies due to poor angularity and coaxiality between the spool and piston end surfaces, leading to increased sliding resistance and deviations in the relationship between pilot pressure and working oil flow, which results in higher manufacturing costs.
Innovation Solution
A fluid pressure control device design that includes a pilot valve, a spool, and a piston with a spherical protrusion and a gap allowing the piston to tilt, ensuring efficient thrust force transfer to the spool, even with poor angularity and coaxiality, by using a second piston that can tilt within the accommodating hole, thereby maintaining planned flow characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high precision is required for spool and piston end surfaces angularity and coaxiality to prevent piston tilting, then thrust force transfer efficiency is improved, but manufacturing costs increase
Solution Approach 1:
The invention introduces a spherical protrusion on the piston that contacts the spool end surface. This spherical geometry allows the piston to self-align and tilt slightly without creating high sliding resistance, as the spherical contact point naturally accommodates angular misalignment. This resolves the contradiction by enabling acceptable thrust force transfer efficiency without requiring high precision angularity between the piston and spool end surfaces, thereby reducing manufacturing costs.
Solution Approach 2:
The invention allows the piston to dynamically tilt within the accommodating hole through the gap provided between the piston outer peripheral surface and the hole inner peripheral surface. This dynamic adjustment capability enables the piston to adapt its orientation to match the spool position, maintaining efficient thrust force transfer even when initial angularity is poor, thus reducing the need for high precision manufacturing.
2Ease of manufacture
If poor angularity and coaxiality exist between spool and piston end surfaces, then manufacturing cost is reduced, but sliding resistance increases and thrust force transfer becomes inefficient
Solution Approach 1:
The spherical protrusion on the piston creates a point contact with the spool end surface that naturally accommodates angular misalignment. This curved geometry allows the piston to tilt and self-align with the spool without generating excessive sliding resistance, maintaining efficient thrust force transfer even when manufacturing precision is relaxed, thereby reducing manufacturing costs.
Solution Approach 2:
The spherical protrusion acts as an intermediary element between the piston and spool. This intermediate spherical contact surface mediates the interaction between the two components, allowing for angular misalignment while maintaining effective force transfer. The spherical mediator absorbs the misalignment effects, enabling poor angularity and coaxiality without significantly impacting thrust force transfer efficiency.
3Manufacturing precision
If the piston is constrained to move only linearly without tilting capability, then manufacturing precision is improved, but the system becomes sensitive to angularity errors and sliding resistance increases
Solution Approach 1:
The invention transforms the piston from a rigid linearly-constrained component to a dynamically adaptable component that can tilt within the accommodating hole. The gap between the piston outer peripheral surface and the hole inner peripheral surface provides the necessary clearance for tilting motion. This dynamic capability allows the piston to compensate for angularity errors between the spool and piston end surfaces, reducing sliding resistance without requiring high manufacturing precision.
Solution Approach 2:
The spherical protrusion on the piston enables curved motion paths during tilting, allowing the piston to smoothly adjust its orientation. This spherical geometry reduces sliding resistance compared to flat surface contact by concentrating contact at a point that can naturally roll or pivot, accommodating angular misalignment without generating excessive friction.
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 design efficiently imparts thrust force to the spool, maintaining planned flow characteristics and reducing manufacturing costs by lowering the precision requirements for the spool, piston, and their sliding components.
Implementation Method 1
a spherical protrusion is provided on a center of either one of a bottom surface of the accommodating hole of the first piston and a back surface of the second piston, and a gap that enables the second piston to tilt within the accommodating hole is formed between an inner peripheral surface of the accommodating hole of the first piston and an outer peripheral surface of the second piston
Implementation Method 2
a piston that is accommodated in the pilot chamber and imparts a thrust force to the spool upon receiving the pilot pressure at its back surface
Implementation Method 3
the piston... imparts a thrust force to the spool upon receiving the pilot pressure at its back surface
Implementation Method 4
a spool that moves according to the pilot pressure of the pilot chamber
Implementation Method 5
an operated check valve that permits a flow of the working fluid from the control valve to the load-side pressure chamber while also permitting a flow of the working fluid from the load-side pressure chamber to the control valve according to a pressure of a back pressure chamber
Data Source
AI summary
A fluid pressure control device includes a switching valve that operates in conjunction with a control valve by a pilot pressure to switch an operation of an operated check valve. The switching valve includes a spool that moves according to the pilot pressure of a pilot chamber, and a piston that is accommodated in the pilot chamber and imparts a thrust force to the spool upon receiving the pilot pressure. The piston includes a first piston that is slidingly accommodated in the pilot chamber and is acted upon by the pilot pressure, and a second piston whose distal end faces the spool and is inserted into an accommodating hole formed in the first piston. A spherical protrusion is provided on a center of either one of a bottom surface of the accommodating hole of the first piston and a back surface of the second piston.