Constant Flow Regulator With Variable Leakage Compensation
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Solution Overview
Problem
Conventional variable flow systems using electrohydraulic servo valves (EHSV) suffer from fixed compensation for slew flow disturbances, which are insensitive to changes in actuator velocity or load, leading to significant flow disturbances on the outlet side.
Innovation Solution
A pressure regulating valve (PRV) with a tunable orifice is used to compensate for slew flow by adjusting leakage based solely on actual slew flow, maintaining a constant flow across the orifice and minimizing additional leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed controlled leak is provided through the EHSV to compensate for slew flow, then some compensation for slew flow is achieved, but the compensation cannot adjust for differences in actuator velocity or changes in load
Solution Approach 1:
The patent transforms the fixed leak path into a dynamic, adjustable leak path by introducing a variable orifice whose opening area changes in response to actuator velocity and load conditions. This allows the compensation mechanism to adapt to varying operational conditions rather than maintaining a constant leak rate.
Solution Approach 2:
The patent changes the physical parameter of the leak path by varying the orifice area dynamically. This is achieved through a spring-loaded mechanism that adjusts the orifice opening based on pressure differential, which reflects actuator velocity and load changes, thereby modifying the leak flow characteristics to match actual slew flow conditions.
2Ease of operation
If high pressure fluid is used for hydraulic actuation of the EHSV, then mechanical positioning of the variable pumping member is achieved, but a large disturbance in the outlet flow is caused
Solution Approach 1:
The patent converts the harmful effect of high-pressure fluid causing flow disturbance into a beneficial compensation mechanism. The high-pressure fluid's tendency to create slew flow is counteracted by introducing a controlled leak path that deliberately allows compensating flow, transforming the disturbance into a balanced system where the leak flow offsets the actuation-induced flow changes.
Solution Approach 2:
The patent introduces an intermediary element - the variable orifice with controlled leak path - that mediates between the high-pressure actuation system and the outlet flow. This intermediary allows a portion of the high-pressure fluid to bypass the main actuation path and flow through the leak path, creating a compensating flow that reduces the net disturbance at the outlet.
3Reliability
If additional leakage paths are added to compensate for slew flow, then flow disturbance is reduced, but the system complexity increases
Solution Approach 1:
The patent merges the compensation function with the existing EHSV structure by integrating the variable orifice and spring mechanism directly into the valve body. Rather than adding a separate, independent compensation device, the solution combines multiple functions (actuation, compensation, and flow regulation) into a single integrated valve assembly, reducing overall system complexity.
Solution Approach 2:
The patent creates a multi-functional component where the EHSV simultaneously performs actuation and slew flow compensation through its integrated variable orifice mechanism. The same valve structure that controls main fluid flow also provides adaptive compensation for slew flow, eliminating the need for separate dedicated compensation devices and reducing system complexity.
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 reduces flow disturbances by up to 50% by compensating solely for slew flow, ensuring a consistent flow output despite actuator movements.
Implementation Method 1
the pressure differential across the orifice serves as an input to a spring-loaded, adjustable orifice that provides an adjustable leak path
Data Source
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AI summary
System designed to compensate for flow disturbances when changing a flow rate in the system, the system including a flow source device (12) having an inlet and an outlet. The inlet is configured to receive fluid at a first pressure, and the outlet is configured to output the fluid at a second pressure that is higher than the first pressure. The system also includes a fluid control device (20) having an inlet port (30) and a drain port (34). The inlet port of the fluid control device is configured to receive flow from the outlet of the flow source device. Further, the system includes a constant flow regulator (68) configured to provide a leakage flow to a drain output (69). The constant flow regulator is configured to decrease the leakage flow in response to the drain port of the fluid control device.