Hydraulic Accumulator Piston Limit Stopper Design
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Solution Overview
Problem
Hydraulic servo-controls in servo-controlled gearboxes are prone to damage and leakage due to traumatic events, leading to system failure, and existing solutions are not cost-effective or reliable.
Innovation Solution
A hydraulic servo-control system with a cylindrical outer housing, a sliding piston, and a limit stopper, such as an annular circlip, that prevents piston displacement and fluid leakage in case of damage, ensuring the system remains operational and cost-effective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple piston structure is used in the hydraulic accumulator, then manufacturing cost is reduced and ease of manufacture is improved, but reliability deteriorates because traumatic damage can remove the partition from the housing causing system failure
Solution Approach 1:
The patent applies beforehand cushioning by providing a limit stopper that prevents the piston from reaching positions where damage could occur. The limit stopper is positioned to stop the piston before it can be removed from the housing due to traumatic damage or excessive depression, thereby preventing system failure in advance.
Solution Approach 2:
The limit stopper acts as an intermediary element between the piston and the housing. It mediates the interaction by providing a physical barrier that prevents the piston from being removed from the housing, thus protecting the system against traumatic damage while maintaining the simplicity of the basic piston structure.
2Device complexity
If no limit stopper is provided, then device complexity is reduced and ease of manufacture is improved, but harmful factors increase because piston displacement can cause considerable leakage and damage to the hydraulic servo-control
Solution Approach 1:
The limit stopper prevents harmful effects by stopping the piston before it can be displaced to a position where damage occurs. This beforehand protection mechanism prevents considerable leakage and damage to the hydraulic servo-control system.
Solution Approach 2:
The limit stopper converts a potential harmful situation (piston displacement leading to damage) into a beneficial outcome by using the stopper itself as a protective feature. The stopper transforms the risk of traumatic damage into a controlled stopping mechanism that protects the system.
3Reliability
If a limit stopper with small opening is used, then reliability is improved by preventing piston removal, but ease of operation deteriorates because the circlip requires considerable force to insert and remove
Solution Approach 1:
The patent resolves the contradiction by changing the dimensional approach - the limit stopper uses a radial interference fit (dimension in the radial direction) to prevent axial removal of the piston. The small opening in the circlip creates radial interference that locks the piston axially, while the circlip itself can still be installed and removed by applying force in the axial direction through specialized tools.
Solution Approach 2:
The circlip with small opening acts as an intermediary locking mechanism that provides reliable piston retention while allowing for controlled installation and removal. The small opening dimension provides the locking function, while the overall circlip structure mediates between the piston and housing, enabling maintenance operations with appropriate tools.
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 system effectively prevents damage to the hydraulic servo-control by stopping piston travel upon potential leakage, maintaining functionality and reducing implementation costs while ensuring reliability.
Implementation Method 1
a hydraulic accumulator containing control fluid under pressure
Implementation Method 2
a first variable-volume chamber for a gaseous material and second variable-volume chamber for the control fluid under pressure
Implementation Method 3
a piston that is arranged and substantially axially slidable and mobile inside the outer housing
Implementation Method 4
partition(s) may include, for example, a bellows element made of a metal material, a flexible partition membrane, or even a piston
Data Source
AI summary
A hydraulic servo-control of a servo-controlled gearbox comprises hydraulic actuators defining chambers, a storing tank containing control fluid used by the actuators at room pressure, a hydraulic accumulator containing control fluid under pressure, a motor pump drawing the fluid from the tank and feeding it under pressure to the accumulator, and solenoid valves selectively connecting the chambers to the tank and accumulator. The accumulator includes an outer housing defining an inner cylindrical surface defining a first diameter, a piston arranged and axially slidable and mobile inside the housing and defining there a first variable-volume chamber for a gas and second variable-volume chamber for the fluid under pressure, and a limit stopper arranged at an open end of the housing, acting as a striker for the piston, and having an annular circlip defining an opening and overall second diameter approximating by excess the first diameter of the surface of the housing.