Fluid Controller Variable Load Sense Orifice Steering Response

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Solution Overview

Problem

Fluid controllers with load sense circuits and flow amplification experience a decline in responsiveness at higher steering speeds, as the flow amplification peaks at around 50 to 60 rpm and then decreases, failing to provide the desired level of responsiveness at faster steering speeds.

Innovation Solution

A fluid controller design featuring a valve assembly with a main flow path, an amplification flow path, and a load sense flow path, including a variable load sense orifice that substantially closes prior to maximum rotational displacement, maintaining maximum amplification orifice area for steering rates between 50 rpm and 150 rpm by increasing delta pressure across the first variable orifice.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the variable load sense orifice closes prior to maximum rotational displacement, then maximum amplification orifice area is maintained for steering rates between 50 rpm and 150 rpm, but the load sense flow path restriction increases

Engineering Contradiction:

Improvesteering speed range with maximum amplificationVSAvoidfluid flow through load sense path

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The load sense orifice creates a localized restriction in the load sense flow path that specifically affects the feedback pressure signal without significantly impacting the main control flow paths. This localized quality change allows the system to maintain amplification benefits while managing fluid flow distribution to achieve the desired steering performance across 50-150 rpm range.

Inventive Principle:

Principle #3Local quality

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 ensures more responsive steering at higher speeds by maintaining the maximum amplification orifice area, allowing increased fluid flow without significant spool deflection, thus enhancing steering performance across a broader range of speeds.

Implementation Method 1

An increase in delta pressure across the first variable orifice of the valve assembly due to the closing of the variable load sense orifice

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

A fluid meter in selective fluid communication with the valve housing and a valve assembly adapted to provide selective fluid communication between the valve housing and the fluid meter

Methodology Applied

Scientific EffectFluid flow control: Hydraulic Press

Data Source

PatentEP3010785B1Fluid controller with load sense and flow amplification

Publication Date: 2020.07.29 EATON INTELLIGENT POWER LTD

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AI summary

A fluid controller includes a valve housing having an inlet port, a return port, first and second control ports and a load sense port. The fluid controller further includes a fluid meter in selective fluid communication with the valve housing and a valve assembly adapted to provide selective fluid communication between the valve housing and the fluid meter. The valve housing includes a main flow path and a load sense flow path. The main flow path is adapted to provide selective fluid communication between the inlet port and the first control port. Fluid in the main flow path passes through the fluid meter. The load sense path is adapted to provide selective fluid communication between the load sense port and the main flow path. The load sense flow path includes a variable load sense orifice that substantially closes prior to a maximum rotational displacement of the valve assembly.