Redundant Steering System with Dual Pump Selector Valves
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional meterless electro-hydraulic steering systems lack a backup mechanism to supply hydraulic fluid to steering cylinders, particularly at high speeds, posing a risk of system failure.
Innovation Solution
A redundant meterless electro-hydraulic steering system is implemented, featuring a primary and secondary power source, each with a variable displacement pump, and paired selector valves controlled by a charge circuit to selectively provide hydraulic fluid from one pump or the other to the steering cylinders, ensuring continuous operation even if one power source fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional meterless EH steering system connects a pump directly to a steering cylinder without a control valve, then the system structure is simplified and response speed is improved, but the system lacks a backup mechanism and reliability deteriorates
Solution Approach 1:
The steering system is segmented into two independent hydraulic circuits: a primary circuit with a first pump and selector valves, and a secondary circuit with a second pump and selector valves. This segmentation allows each circuit to operate independently, so that if one circuit fails, the other can take over, thus improving reliability while maintaining the simplified meterless structure of each individual circuit.
Solution Approach 2:
The system incorporates a backup pump and selector valves in advance, before any failure occurs. The selector valves are pre-configured to switch between the primary and secondary pumps, and the backup pump is ready to supply hydraulic fluid immediately upon detection of a failure in the primary system, ensuring continuous operation without interruption.
2Reliability
If a backup pump and selector valves are added to create a redundant steering system, then reliability is improved, but device complexity increases
Solution Approach 1:
The primary and secondary hydraulic circuits are merged into a single integrated steering system that shares common components such as the steering cylinder, hydraulic fluid reservoir, and control architecture. The selector valves intelligently route hydraulic fluid from either the primary or secondary pump to the steering cylinder, combining the redundancy benefit of two pumps with the simplicity of a unified system structure.
Solution Approach 2:
The selector valves serve multiple functions: they selectively connect either the primary pump or secondary pump to the steering cylinder, they enable automatic failover between pumps, and they maintain system pressure regulation. This multi-functionality reduces the need for additional dedicated components, thereby limiting the increase in overall system complexity while achieving reliability through redundancy.
3Reliability
If the primary power source fails at high speed, then the vehicle can no longer be steered safely, but adding a secondary power source increases system complexity
Solution Approach 1:
The selector valves act as intermediary devices between the primary/secondary power sources and the steering cylinder. They automatically detect failures in the primary power source and switch the hydraulic fluid supply to the secondary power source, ensuring continuous steering capability at high speeds without requiring complex manual intervention or reconfiguration of the power source system.
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 solution provides a fail-safe mechanism that maintains steering functionality by switching hydraulic fluid supply from one power source to another upon detection of a fault, ensuring the system remains operational at high speeds and preventing potential failures.
Implementation Method 1
a charge circuit coupled to respective control inputs of the first and second pairs of selector valves and configured to selectively supply hydraulic fluid to the control inputs of the first and second pairs of selector valves to stop hydraulic fluid from only one of the first pump and the second pump from being provided to the at least one steering cylinder and to provide hydraulic fluid to the at least one steering cylinder from only one of the other of the first pump and the second pump
Data Source
AI summary
A redundant steering system comprises a primary power source; a secondary power source; first and second pumps operatively coupled to the primary and secondary power sources, respectively, to output first and second supplies of hydraulic fluid to a steering cylinder based on operation of the primary and secondary power source, respectively; first and second pairs of selector valves respectively coupled to the first and second pumps; and a charge circuit coupled to respective control inputs of the first and second pairs of selector valves to selectively supply hydraulic fluid to the control inputs of the first and second pairs of selector valves to stop hydraulic fluid from only one of the first pump and the second pump from being provided to the steering cylinder and to provide hydraulic fluid to the steering cylinder from only one of the other of the first pump and the second pump.