Hydraulic Parallel Work System for Reliable Steering Control

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Solution Overview

Problem

Existing hydraulic systems face challenges in efficiently and reliably controlling fluid flow and pressure to perform precise and automated steering operations, particularly when failures occur in the closed-center circuit or modulating valve, leading to hydraulic interference and potential steering failures.

Innovation Solution

A hydraulic parallel work system incorporating a fixed displacement pump, closed-center circuit, and open-center hand metering unit (HMU) with enable, steering, and modulating valves, allowing for parallel operation and fail-safe fluid communication to ensure uninterrupted steering, even in the event of circuit failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single hydraulic circuit is used for steering control, then the system structure is simple, but the reliability decreases when failures occur in the circuit or valve

Engineering Contradiction:
Improvesteering control reliabilityVSAvoidhydraulic circuit structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The hydraulic steering system is divided into two independent parallel circuits: a closed-center circuit for automated steering control and an open-center hand metering unit circuit for manual steering control. Each circuit can operate independently, so a failure in one circuit does not affect the other, thereby improving reliability while maintaining manageable structural complexity through functional segmentation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different parts of the system have different operational characteristics optimized for their specific functions. The closed-center circuit is optimized for automated control with precise flow control, while the open-center hand metering unit is optimized for manual operation with direct flow control. This local optimization allows each subsystem to perform its function reliably without requiring the entire system to be overly complex.

Inventive Principle:
Principle #3Local quality

2Reliability

If parallel hydraulic circuits are implemented, then the reliability improves, but the device complexity increases

Engineering Contradiction:
Improvecontinuous steering functionalityVSAvoidfluid communication arrangement
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A modulating valve is introduced as an intermediary component that controls the fluid communication between the two parallel hydraulic circuits. The modulating valve regulates the interaction between the closed-center circuit and the open-center hand metering unit, allowing selective activation of either circuit while preventing harmful interactions. This intermediary simplifies the overall fluid communication arrangement by providing a single control point for managing the parallel circuits.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the closed-center circuit fails, then the automated steering control is lost, but the manual steering may be affected by hydraulic interference

Engineering Contradiction:
Improvesteering control continuityVSAvoidhydraulic interference
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The hand metering unit is extracted as a separate, independent circuit from the closed-center automated steering circuit. This extraction ensures that failures in the closed-center circuit cannot cause hydraulic interference in the manual steering circuit. The hand metering unit maintains its own independent fluid path and control mechanism, allowing manual steering to continue reliably even when automated control fails.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system design anticipates potential failures in the closed-center circuit by providing the open-center hand metering unit as a pre-prepared backup. The hand metering unit is always ready to take over steering control without requiring any active intervention, providing beforehand cushioning against the harmful effects of closed-center circuit failures. This backup capability prevents hydraulic interference from affecting manual steering operation.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 provides reliable and precise steering control by enabling parallel operation of hydraulic circuits, ensuring continuous functionality even in the event of failures, thus maintaining vehicle maneuverability and operational efficiency.

Implementation Method 1

A hydraulic parallel work system includes a fixed displacement pump and a closed-center circuit in fluid communication with the fixed displacement pump

Methodology Applied
Scientific EffectHydraulic fluid flow:

Implementation Method 2

The closed-center circuit includes a steering valve and an enable valve where the enable valve is in fluid communication with the steering valve and includes a first position and a second position

Methodology Applied
Scientific EffectValve-controlled fluid flow: Valve

Implementation Method 3

the system may include a modulating valve with an input port in fluid communication with the fixed displacement pump and an output port in fluid communication with the inlet port of the HMU

Methodology Applied
Scientific EffectFluid metering:

Implementation Method 4

A hydraulic circuit generally includes components performing operations based on fluid dynamics

Methodology Applied
Scientific EffectHydraulic force conversion:

Data Source

PatentEP3867125B1Hydraulic parallel work systems
Publication Date: 2026.01.28 FEMA CORP OF MICHIGAN
  • EP3867125B1 patent drawingFigure 1
  • EP3867125B1 patent drawingFigure 2
  • EP3867125B1 patent drawingFigure 3

AI summary

A system for hydraulic parallel work systems is provided. The system includes a fixed displacement pump (110), a closed-center circuit (300), an open-center hand metering unit (HMU) (200), and a tank (120). The closed-center circuit is in fluid communication with the fixed displacement pump. The open-center HMU is in fluid communication with the fixed displacement pump at an inlet port (204) of the HMU. The tank is fluidly connected to the inlet port of the HMU when the HMU is inactive.