Hydraulic Steering Arrangement with Manual Mode Isolation
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Solution Overview
Problem
The hydraulic steering arrangement is at risk of losing control when the steering valve malfunctions, particularly due to sticking issues, which can lead to unpredictable steering behavior.
Innovation Solution
Incorporating a cut-off valve and check valves to control the flow to the working port arrangement through the steering unit in manual steering mode, ensuring the driver maintains control, and isolating the steering unit from the working port in automatic steering mode to prevent unintended fluid supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the steering valve is used to automatically steer the vehicle, then the automation capability is improved, but the reliability deteriorates because the steering valve can malfunction or stick
Solution Approach 1:
The steering unit acts as an intermediary between the steering valve and the working port arrangement. In manual steering mode, the steering unit mediates the hydraulic fluid flow from the steering valve, allowing the driver to control the amount of fluid supplied to the working port arrangement even when the steering valve malfunctions or sticks.
Solution Approach 2:
The hydraulic steering system is segmented into distinct functional blocks: the steering valve for automated control, the steering unit for manual control and flow regulation, and the working port arrangement for executing steering actions. This segmentation allows each component to be independently controlled and failsafe-designed.
2Device complexity
If the steering valve is connected directly to the working port arrangement, then the device complexity is reduced, but the reliability deteriorates due to loss of control on valve malfunction
Solution Approach 1:
The steering unit serves as a mandatory intermediary component between the steering valve and the working port arrangement. This intermediary structure adds one level of control complexity but provides critical safety by allowing the driver to regulate hydraulic fluid flow independently of the steering valve's condition.
3Adaptability or versatility
If the steering valve can operate in both directions, then the adaptability is improved for automatic steering modes, but the reliability deteriorates due to risk of reverse steering flows
Solution Approach 1:
The system dynamically adjusts the steering valve's operational capabilities based on the steering mode. In manual steering mode, the steering valve is configured to operate in one direction only, with the steering unit providing bidirectional control capability. In automatic steering mode, the steering valve can operate in both directions for full adaptability.
Solution Approach 2:
Different directional control characteristics are applied to different parts of the system. The steering unit provides one-way flow control in manual mode, while the steering valve provides bidirectional control in automatic mode. This localized differentiation of control properties optimizes both reliability and adaptability for their respective operating contexts.
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 configuration reduces the risk of steering valve failure by allowing the driver full control in manual mode and ensuring safe operation in automatic mode by preventing reverse steering flows and isolating the steering unit from the working port, thus maintaining vehicle control.
Implementation Method 1
reverse steering flow through the steering valve is prevented by means of a check valve
Implementation Method 2
the steering valve outlet flow is allowed in one direction and blocked in the other direction by means of a cut-off valve
Implementation Method 3
The hydraulic fluid flowing from the supply port arrangement to the working port arrangement flows through the measuring motor
Data Source
AI summary
A hydraulic steering arrangement (1) is described comprising a supply port arrangement having a pressure port (P) and tank port (T), a working port arrangement having two working ports (L, R), a steering unit (2) arranged between the supply port arrangement and the working port arrangement and a steering valve (3) arranged between the supply port arrangement and the working port arrangement. Such a steering arrangement should have a safety means. To this end in a manual steering mode the steering valve (3) is connected to the working port arrangement through the steering unit (2).