Hydraulic Power Control Circuit with Shared Pressure Compensator

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Solution Overview

Problem

Existing hydraulic control circuits for construction vehicles are either costly due to the need for multiple pressure compensators in load sensing technology or require skilled operators for proportional control with open center technology.

Innovation Solution

A load sensing hydraulic control circuit that shares a pressure compensator between two control valves, allowing differential pressure control and proportional actuator operation, reducing component count and cost while maintaining efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If load sensing technology is used with a pressure compensator for each control valve, then proportional control of actuators is achieved, but the number of components and cost increase

Engineering Contradiction:
Improveproportional control of actuatorsVSAvoidnumber of pressure compensators
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent merges the functions of multiple pressure compensators into a single pressure compensator that serves multiple control valves. The pressure compensator is positioned in the common supply line upstream of multiple control valves, and through hydraulic coupling, it regulates differential pressure across all control valves simultaneously, eliminating the need for individual pressure compensators at each valve.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single pressure compensator is designed to perform multiple functions: it regulates differential pressure across multiple control valves, provides load sensing pressure signals to the pump unit, and enables proportional control for all actuators connected to the control valves. This multi-functional design reduces component count while maintaining control capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Device complexity

If open center control circuit is used, then cost is reduced, but proportional control of actuators becomes impossible

Engineering Contradiction:
Improvecontrol circuit simplicityVSAvoidproportional control capability
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The patent introduces a load sensing line as an intermediary hydraulic circuit that carries pressure signals from the actuators back to the pump unit. This load sensing line enables the pump to respond to actual load conditions and adjust flow accordingly, providing proportional control capability while maintaining the simpler open center control valve architecture.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If multiple pressure compensators are used in load sensing circuit, then proportional control is achieved, but cost increases

Engineering Contradiction:
Improveproportional control of actuatorsVSAvoidmanufacturing cost
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The patent merges the functions of multiple pressure compensators into a single pressure compensator that serves multiple control valves. The pressure compensator is positioned in the common supply line upstream of multiple control valves, and through hydraulic coupling, it regulates differential pressure across all control valves simultaneously, eliminating the need for individual pressure compensators at each valve.

Inventive Principle:
Principle #5Merging (Combining)

4Device complexity

If a single pressure compensator is shared between control valves, then component count and cost are reduced, but differential pressure control must be maintained across multiple valves

Engineering Contradiction:
Improvenumber of pressure compensatorsVSAvoiddifferential pressure control stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent extracts the pressure regulation function from individual control valves and centralizes it in a single pressure compensator located in the common supply line. This separation allows the pressure compensator to independently regulate differential pressure for all control valves without being influenced by the specific operating conditions of individual valves, improving control stability.

Inventive Principle:
Principle #2Taking out (Extraction)

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 solution provides a cost-effective and efficient means of controlling multiple actuators in construction vehicles, achieving proportional control without the need for multiple pressure compensators, thus reducing the complexity and expense of the hydraulic control system.

Implementation Method 1

a pressure compensator elaborates both a load sensing pressure signal to control a pump unit and an output power flow that is either split or alternatively directed to at least a first and a second actuator control valves so that a differential pressure across the first and second control valves is controlled by the pressure compensator

Methodology Applied
Scientific EffectHydraulic pressure control: Hydraulic Press

Data Source

PatentEP3443168B1Hydraulic power control circuit and construction vehicle comprising such circuit
Publication Date: 2020.11.18 CNH IND ITALIA SPA
  • EP3443168B1 patent drawingFigure 1
  • EP3443168B1 patent drawingFigure 2
  • EP3443168B1 patent drawingFigure 3

AI summary

In a load sensing hydraulic control circuit, a pressure compensator elaborates both a load sensing pressure signal to control a pump unit and a pressure compensated power flow for actuators, the power flow being either split or alternatively directed to at least a first and a second actuator control valves so that a differential pressure across the first and second control valves is controlled by the pressure compensator. In one embodiment, the circuit is onboard a construction vehicle to power actuators such as travel left, travel right, swing, boom, arm, bucket and the like.