Pilot-Operated Relief Valve Low-Pressure Fluid Dump

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Solution Overview

Problem

Conventional hydraulic systems face issues with excessive fluid being dumped back to the tank at high pressures during retraction, leading to energy wastage and heat generation, and existing solutions either result in internal leakage or increase system complexity by adding additional valves.

Innovation Solution

A pilot-operated extend relief valve design utilizing a spool valve to open the valve during retraction, leveraging a larger surface area for mechanical advantage to reduce the pressure required for fluid return, thus allowing low-pressure fluid to be released to the reservoir without additional valves.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a retract relief valve is used to dump excess fluid to tank, then the fluid can be returned to reservoir, but the fluid is dumped at excessively high pressures causing heat generation and energy wastage

Engineering Contradiction:

Improveenergy wastageVSAvoidfluid pressure

Core Design Contradiction:

Loss of energyVSStress or pressure

Solution Approach 1:

A pilot spool valve is introduced as an intermediary device to control the opening of the extend relief valve. The pilot spool responds to pressure differential between piston side and rod side, selectively opening the extend relief valve to dump excess fluid at low pressure during retraction, thereby eliminating high-pressure energy waste while still returning fluid to reservoir

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically changes the pressure parameter at which fluid is dumped to tank. During retraction, the extend relief valve is piloted to open at low pressure (not the high relief valve setting), transforming the dump pressure from excessively high to appropriately low, thus reducing energy wastage and heat generation

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If an additional relief valve and pilot operated check valve are added to allow low pressure fluid return, then heat and energy issues are addressed, but system complexity and cost increase

Engineering Contradiction:

Improveenergy wastageVSAvoidvalve quantity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The extend relief valve is designed to serve dual functions: (1) its primary function as a high-pressure relief valve during extension, and (2) a piloted low-pressure dump valve during retraction. This multi-functionality eliminates the need for separate dedicated dump valve components, reducing system complexity while still addressing energy wastage and heat generation issues

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The pilot spool valve mechanism is merged with the existing extend relief valve assembly, combining the piloting function and relief function into a single integrated component. This merging eliminates the need for separate additional valves and reduces internal leakage paths, thereby addressing energy efficiency without increasing system complexity

Inventive Principle:

Principle #5Merging (Combining)

3Loss of energy

If an additional relief valve and pilot operated check valve are added to allow low pressure fluid return, then heat and energy issues are addressed, but internal leakage issues increase

Engineering Contradiction:

Improveenergy wastageVSAvoidinternal leakage

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The pilot spool valve is integrated within the extend relief valve body, merging the piloting mechanism and relief function into a single sealed assembly. This integration reduces the number of external connections and potential leakage paths compared to separate valves, thereby addressing energy efficiency while minimizing internal leakage and improving reliability

Inventive Principle:

Principle #5Merging (Combining)

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 effectively reduces energy wastage and heat generation while maintaining system performance and reducing complexity by eliminating the need for additional valves, thereby enhancing efficiency and reliability.

Implementation Method 1

The first spool is configured to press against and thereby open the extend relief valve when the first spool is energized by relatively high pressure fluid on the first side

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

leveraging a larger surface area for mechanical advantage to reduce the pressure required for fluid return

Methodology Applied

Scientific EffectMechanical advantage: Mechanical Advantage

Implementation Method 3

The first check valve has a flow side and a block side and is configured to open when relatively high pressure fluid impinges on the flow side

Methodology Applied

Scientific EffectPressure-driven valve opening: Pressure Gradient

Data Source

PatentUS9234533B2Electro-hydraulic pilot operated relief valve

Publication Date: 2016.01.12 PARKER INTANGIBLES LLC

AI summary

Provided is a method of and valve assembly for dumping excess fluid during retraction of a cylinder actuator. The method includes pumping fluid with a pump from a piston side of the cylinder to a rod side of the cylinder; opening a first check valve with relatively high pressure fluid from a downstream side of the pump to allow flow into the rod side of the cylinder; and opening an extend relief valve via a first spool with fluid from the downstream side of the pump to allow excess fluid at an upstream side of the pump to return to a reservoir at relatively low pressure.