Steering System with Safety Valve for Low-Pressure Steerability

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Solution Overview

Problem

Existing steering systems do not provide optimal comfort and may fail to ensure continuous vehicle steerability in low-pressure conditions.

Innovation Solution

A steering system that includes a hydraulic circuit with a variable orifice for creating flow resistance, connected to an electro-hydraulic steering valve via a safety valve. The safety valve automatically establishes a hydraulic connection between the hydraulic circuit and the working port arrangement in case of low pressure, ensuring continuous steerability without additional connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a hydraulic circuit with flow resistance means is used to create steering feel, then steering comfort is improved, but the system may fail to ensure continuous steerability in low-pressure conditions

Engineering Contradiction:
Improvesteering comfortVSAvoidcontinuous steerability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The safety valve is pre-configured with a valve opening that automatically activates when supply pressure drops below a threshold level. This preliminary arrangement ensures that the alternative hydraulic path is ready to engage immediately when needed, maintaining steerability without requiring active control intervention during low-pressure events.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The safety valve acts as an intermediary component between the supply port arrangement and the working port arrangement. It provides an alternative hydraulic pathway that bypasses the electro-hydraulic steering valve when supply pressure is insufficient, ensuring continuous operation through this intermediate route.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If the safety valve is connected via the steering valve, then no additional connections are necessary, but the steering valve must handle additional flow paths

Engineering Contradiction:
Improveconnection complexityVSAvoidsteering response speed
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The safety valve is integrated into the existing steering valve assembly, sharing common hydraulic pathways and structural components. This merging approach allows the safety valve to connect to the working port arrangement through the steering valve without requiring separate external connections, reducing overall system complexity while maintaining functional independence.

Inventive Principle:
Principle #5Merging (Combining)

3Adaptability or versatility

If the variable orifice is used to adjust flow resistance, then steering feel can be adapted to different driving situations, but the device complexity increases

Engineering Contradiction:
Improvesteering feel adaptationVSAvoidflow resistance control
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The orifice is designed with a variable cross-sectional area that can dynamically adjust the flow resistance characteristics. This dynamic geometry allows the flow resistance means to adapt to different operating conditions and steering scenarios, providing optimized steering feel across various driving situations without requiring multiple separate components.

Inventive Principle:
Principle #15Dynamics

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 improved comfort through adjustable steering feel and ensures continuous vehicle steerability by automatically engaging the safety valve in low-pressure conditions, maintaining vehicle control.

Implementation Method 1

the circuit shows a certain flow resistance for the pumped fluid. Thus, rotating the steering wheel has to overcome a certain torque

Methodology Applied
Scientific EffectFlow resistance: Drag

Implementation Method 2

a safety valve establishing or interrupting a hydraulic flow path between the hydraulic circuit and the steering valve

Methodology Applied
Scientific EffectPressure-dependent valve operation: Valve

Data Source

PatentEP4311740B1Steering system
Publication Date: 2025.01.29 DANFOSS POWER SOLUTIONS APS
  • EP4311740B1 patent drawingFigure 1~2
  • EP4311740B1 patent drawingFigure 3

AI summary

A steering system (1) is described comprising a supply port arrangement having a supply port (P) and a return port (T), a steering command arrangement having a steering sensor (5), a controller (9) connected to the steering sensor (5), an electro-hydraulic steering valve (8) controlled by the controller (9), and a working port arrangement having two working ports (L, R), wherein the working port arrangement is connected to the supply port arrangement by means of the steering valve (8). Such a steering system should have a good comfort. To this end the steering command arrangement comprises a steering wheel (4) connected to a hydraulic pumping unit (7), wherein the pumping unit (7) is part of a hydraulic circuit (11) having means for creating a flow resistance.