Electro-Hydraulic Steering with Accumulator Backup Pressure Control
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Solution Overview
Problem
Conventional hydraulic power steering systems in work vehicles face increased effort and slower operation in emergency conditions due to the absence of hydraulic fluid, necessitating additional electric pumps, which incur significant cost and complexity.
Innovation Solution
Implementing a hydraulic accumulator in the system to provide hydraulic oil in emergencies, coupled with an activation logic that manages the electric pump to serve both the steering system and the accumulator, thereby avoiding the need for a second electric pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a second electric pump is implemented to provide hydraulic fluid in emergency conditions, then safety requirements are met, but vehicle cost increases significantly
Solution Approach 1:
The hydraulic accumulator is pre-charged with hydraulic fluid before emergency conditions occur. This preliminary storage of fluid allows the system to immediately respond to steering emergencies without requiring a second pump, thereby meeting safety requirements while avoiding the cost increase associated with additional pumping components
Solution Approach 2:
The hydraulic accumulator acts as an intermediary component between the single electric pump and the steering system. It stores hydraulic fluid and releases it during emergencies, mediating the need for continuous pump operation and eliminating the requirement for a second pump, thus reducing system complexity and cost while maintaining safety
2Reliability
If a second electric pump is implemented to ensure hydraulic fluid supply in emergencies, then safety standards are complied with, but system complexity increases
Solution Approach 1:
The accumulator is pre-filled with hydraulic fluid under pressure before emergencies occur. This preliminary preparation ensures that fluid is immediately available when needed, maintaining supply reliability without the complexity of a second pump system
Solution Approach 2:
The function of providing emergency hydraulic fluid is extracted from the pump system and placed into the accumulator. This separation allows the pump system to remain simple with a single pump, while the accumulator independently handles emergency fluid supply, reducing overall system complexity
3Productivity
If the electric pump continuously supplies hydraulic fluid to the steering system, then steering operation is efficient, but the accumulator cannot be recharged
Solution Approach 1:
The system dynamically switches between pump-to-steering and pump-to-accumulator modes based on real-time conditions. When the steering system requires fluid, the pump supplies it directly; when the accumulator pressure drops below the threshold, the system redirects pump output to recharge the accumulator, ensuring both efficient steering operation and accumulator availability
Solution Approach 2:
The processing means continuously monitors accumulator pressure and uses this feedback to control pump operation. When pressure falls below the threshold, the system activates the pump to recharge the accumulator; when pressure is sufficient, the system allows efficient steering operation. This feedback mechanism ensures both productivity and duration requirements are met
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
Ensures compliance with safety standards while reducing costs and complexity by providing hydraulic fluid in emergencies, ensuring efficient steering operation without the need for a second electric pump.
Implementation Method 1
a pressure value measured in said hydraulic accumulator is lower than a predetermined threshold
Implementation Method 2
implement a hydraulic accumulator in place of a second electric pump, which in emergency conditions is able to provide a flow of hydraulic oil
Data Source
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AI summary
Electro-hydraulic steering system (C) comprising an electric pump (HP) arranged to power a steering device (HSA), processing means (CPU) configured to deactivate said electric pump in response to deactivation of the steering device and wherein the system comprises a hydraulic accumulator (EHP) operatively connected with said electric pump and with said steering device and wherein said processing means is configured to activate said electric pump in response to activation of the steering device and when a pressure value measured in said hydraulic accumulator (EHP) is greater than a first predetermined threshold (Th1) and less than or equal to a second predetermined threshold (Th2).