Hydraulic Steering Flow Circuit With Automatic Pump Backup
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Solution Overview
Problem
Existing power-steering systems in work vehicles lack safety enhancements, user friendliness, and cost efficiency, particularly in hydraulic circuits, which are crucial for passing homologation tests.
Innovation Solution
A fluid control arrangement is introduced in the hydraulic circuit, incorporating a first and second pump system with a flow direction control device, emergency valve, and pressure sensors to manage fluid flow, ensuring redundancy and efficient backup operation, and includes a priority valve for load-sensing and emergency responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single pump system is used in the hydraulic circuit, then the device complexity is reduced, but the reliability of the power steering system deteriorates due to lack of backup operation capability
Solution Approach 1:
The hydraulic circuit is segmented into multiple independent flow paths (first flow path with first pump, second flow path with second pump) that can operate independently. This segmentation allows the system to maintain reliability through redundancy while managing complexity by organizing each path with similar components.
Solution Approach 2:
The flow direction control device is pre-configured to automatically switch between pumps based on pressure conditions. The backup second pump is prepared in advance with its flow path ready to activate when the primary first pump fails, ensuring immediate backup operation without manual intervention.
2Reliability
If flow direction control devices and emergency valves are added to enable backup operation, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The flow direction control device serves multiple functions: it normally directs fluid flow from the first pump, automatically switches to the second pump when pressure drop occurs, and can operate in different modes based on pressure conditions. This multi-functionality reduces the need for separate dedicated backup components.
Solution Approach 2:
The emergency valve is controlled via a control port that receives feedback from the pressure condition in the first flow path. When pressure drops below a threshold, this feedback mechanism automatically activates the second flow path, creating a self-regulating backup system that responds dynamically to actual operating conditions.
3Ease of operation
If pressure sensing control connections are implemented, then the user friendliness and safety are improved through automatic backup activation, but the device complexity and manufacturing cost increase
Solution Approach 1:
The system uses self-service through automatic pressure-sensing control that detects pump failure conditions and activates the backup second pump without requiring operator intervention. The flow direction control device and emergency valve work autonomously based on pressure feedback, eliminating the need for complex manual monitoring and switching mechanisms.
4Reliability
If the second flow path is kept ready for emergency operation, then the reliability is improved, but the fluid flow control complexity and energy consumption increase
Solution Approach 1:
The system dynamically adjusts which pump operates based on real-time pressure conditions. The first pump operates normally during standard conditions, while the second pump remains in standby mode ready to activate. This dynamic switching optimizes energy consumption by keeping only the necessary pump running at any given time while maintaining backup readiness.
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
Enhances safety, user friendliness, and cost efficiency by providing reliable backup operations and failure diagnostics, ensuring seamless power steering functionality even under pressure drops.
Implementation Method 1
a flow direction control device (e.g. a check valve) arranged and configured to prevent a flow of the fluid to the first inlet in response to a pressure difference across the flow direction control device
Implementation Method 2
a control connection to the control port for controlling the opening of the second flow path in response to a pressure drop in a section of the fluid circuit between the first pump and the flow direction control device
Data Source
AI summary
An arrangement for controlling a fluid circuit's flow from alternatively a first and a second pump to a tank via steering unit and steering cylinder of the circuit is disclosed. The arrangement comprises a first flow path including a flow direction control device for preventing a flow to a first inlet in response to a pressure difference across the device, a second flow path including an emergency valve for opening of the second flow path comprising and controlled via a control port a connection between the first and the second flow path in accordance with a position of the flow direction control device between the emergency valve and the first inlet; and a connection for responding to a pressure drop between the first pump and the flow direction control device by opening of the second flow path.