Pilot-Operated Hydraulic Valve for Fast Cylinder Pressure Relief
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Solution Overview
Problem
There is a need for a hydraulic valve and control system that can quickly move components of patient handling apparatuses, such as emergency cots, without causing unacceptable pressure increases in hydraulic cylinders, to facilitate faster loading and unloading of patients.
Innovation Solution
A hydraulic circuit with a pilot operated control valve that selectively opens fluid communication between chambers based on hydraulic fluid flow rates, allowing for rapid evacuation of fluid from the cap end chamber to the reservoir, thereby maintaining acceptable pressure and enabling quicker movement of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hydraulic fluid is quickly evacuated from the cap end chamber to increase component movement speed, then the speed of moving the base is improved, but the hydraulic pressure may increase to unacceptable levels
Solution Approach 1:
A bypass valve is introduced as an intermediary component that provides an alternative fluid path. When main relief valve 104 fails to open due to excessive spring force, the bypass valve 154 acts as a mediator to relieve pressure by allowing hydraulic fluid to flow from the cap end chamber 84a back to the reservoir 94 through a separate bypass passage 152, thus preventing unacceptable pressure buildup while enabling faster base movement.
Solution Approach 2:
The pressure relief function is segmented into two separate valve systems: a main relief valve 104 for normal operating conditions and a bypass valve 154 for emergency or high-flow conditions. This segmentation allows each valve to be optimized for its specific function, with the bypass valve having a lower spring force requirement to activate during rapid base retraction when the main valve remains closed.
2Measurement precision
If a pilot operated control valve is used to control fluid flow based on flow rate, then the control precision is improved, but the device complexity increases
Solution Approach 1:
The pilot operated flow control valve 140 utilizes the hydraulic fluid's own flow characteristics to control valve opening. The valve leverages the back pressure generated by high flow rates through the rod end chamber 84b to automatically pilot-open the cap end relief path, eliminating the need for external sensors, actuators, or complex electronic controls. The system self-regulates based on flow conditions.
Solution Approach 2:
The patent employs hydraulic pilot pressure to control the main valve opening. High flow rates through the rod end chamber create back pressure that is transmitted to pilot the cap end relief valve 154, causing it to open. This purely hydraulic control mechanism replaces complex electronic or mechanical control systems while achieving precise flow rate-based control.
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 solution allows for the rapid and controlled movement of components, reducing stress on caregivers and increasing the speed of patient handling and delivery to medical facilities while maintaining acceptable hydraulic pressure.
Implementation Method 1
When the fluid flow to the first inlet of the first chamber exceeds a preselected flow rate, back pressure at the inlet of the first chamber will move the pilot piston and cause the pilot rod to move the valve poppet from its closed position to one of its open positions
Data Source
AI summary
An apparatus includes a hydraulic circuit that is configured to selectively open fluid communication between one portion of the hydraulic circuit and another portion of the hydraulic circuit, such as a reservoir, based on the flow of the hydraulic fluid in the one portion. When the flow of hydraulic fluid exceeds a selected threshold in the one portion of the hydraulic circuit, the flow of fluid urges the opening of a hydraulic component of the hydraulic circuit to allow fluid communication between the one portion and the reservoir to discharge fluid from the one portion.