Electro-Hydraulic Steering Circuit with Precharge Valve
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Solution Overview
Problem
Current steering systems in work vehicles face inefficiencies due to high parasitic loss when providing constant hydraulic flow, leading to either high response rates with significant energy loss or low response rates with prolonged fluid pressure build-up, which can cause steering lag.
Innovation Solution
An electro-hydraulic steering circuit with a load sensing pump, precharge valve, and controller that dynamically adjusts hydraulic fluid flow based on pressure differentials and user input, diverting fluid to minimize parasitic loss and ensure rapid pressure build-up for quick response steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If constant hydraulic flow is provided to the steering system, then rapid steering response is achieved, but parasitic loss increases significantly
Solution Approach 1:
The system dynamically adjusts the hydraulic flow from constant to variable based on steering demand. The load sensing pump modulates its output according to the pressure differential detected by the precharge valve, providing high flow during steering activation and reduced flow during idle periods, thus resolving the contradiction between rapid response and energy loss.
Solution Approach 2:
The precharge valve maintains a precharge pressure in the steering circuit during idle periods, preparing the system for rapid response without requiring constant full-flow operation. This preliminary pressurization allows quick steering activation while avoiding continuous high-flow parasitic loss.
2Loss of energy
If hydraulic flow is reduced to minimize parasitic loss, then energy efficiency improves, but fluid pressure build-up time increases causing steering lag
Solution Approach 1:
The precharge valve maintains a precharge pressure in the steering circuit during idle periods, preparing the system for rapid response. This preliminary pressurization ensures that when steering is activated, the pressure build-up time is minimized while the system remains energy-efficient during non-use.
Solution Approach 2:
The load sensing pump uses pressure differential feedback from the precharge valve to modulate its output. When the precharge pressure drops below a threshold, the pump increases flow to restore pressure, automatically balancing energy efficiency with response time requirements.
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 achieves a balance between rapid steering response and reduced parasitic loss by optimizing hydraulic fluid flow, providing efficient and responsive steering without unnecessary energy consumption.
Implementation Method 1
The load sensing system increases or decreases output from the load sensing pump in response to a pressure differential between a first fluid line and a second fluid line
Implementation Method 2
A precharge valve diverts hydraulic fluid from the first fluid line to the second fluid line
Data Source
AI summary
A quick response steering system with a steering device that steers a vehicle. An electro-hydraulic steering circuit couples to the steering device. The electro-hydraulic steering circuit includes a load sensing pump that pumps hydraulic fluid to a steering cylinder. The load sensing pump increases or decreases output from the load sensing pump in response to a pressure differential between a first fluid line and a second fluid line. A precharge valve diverts hydraulic fluid from the first fluid line to the second fluid line. A controller couples to the steering device and the precharge valve. The controller opens the precharge valve in response to input from the steering device to change a first pressure of the first fluid line to increase an output of the load sensing pump.