Dual-Pump Power Steering Control for Smooth Assistance Transitions
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Solution Overview
Problem
Existing power steering systems in heavy-duty vehicles face challenges with fully electric solutions being expensive and dual pump systems causing steering wheel feedback and drivability issues due to pump transitions.
Innovation Solution
A power steering system with a controllable first pump driven by the vehicle's propulsion source and a second pump driven by wheel rotation, operating in parallel to provide smooth assistance, controlled by a power steering control system to maintain consistent fluid flow and minimize steering wheel feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fully electric power steering solution is used, then power steering assistance can be provided independently of the combustion engine, but the system becomes expensive requiring either a BEV or a dedicated 48V battery
Solution Approach 1:
The patent merges the electric pump system with the existing hydraulic power steering circuitry, combining the benefits of electric independence with the proven hydraulic assistance mechanism. The electric pump integrates into the common power steering fluid circuit, allowing independent operation without requiring a complete system overhaul or dedicated battery infrastructure.
Solution Approach 2:
The power steering control system is designed to universally accept multiple power sources - it can operate with the combustion engine driving the first pump, the electric motor driving the second pump, or both simultaneously. This multi-functionality allows the system to adapt to different operating conditions without requiring separate dedicated systems for each power source.
2Reliability
If dual power steering pumps are used for safety purposes, then redundancy is achieved, but steering wheel feedback and drivability issues occur due to pump transitions
Solution Approach 1:
The control system dynamically manages the operation of dual pumps by continuously adjusting their individual contributions based on real-time conditions. The controller monitors steering demands, vehicle speed, and pump performance to optimize the distribution of hydraulic flow, ensuring smooth transitions and consistent steering assistance throughout operation.
Solution Approach 2:
The power steering control system incorporates feedback mechanisms that monitor the performance of both pumps and the overall steering system. This feedback enables the controller to detect and compensate for transitions between pumps, maintaining consistent steering wheel feedback and preventing drivability issues by adjusting pump operation in response to system conditions.
3Device complexity
If a single controllable pump driven by the propulsion source is used, then system complexity is reduced, but the pump cannot provide adequate assistance when the propulsion source is not running
Solution Approach 1:
The patent segments the power steering pump function into two separate pumps - a first pump driven by the propulsion source for normal operation, and a second electrically driven pump for operation when the propulsion source is not running. This segmentation allows each pump to be optimized for its specific driving condition while maintaining overall system simplicity through a shared control architecture.
Solution Approach 2:
The power steering control system acts as an intermediary that coordinates between the propulsion source, the two pumps, and the steering actuator. It mediates the transition between different power sources and ensures seamless operation by managing the hydraulic circuit to maintain consistent assistance levels regardless of which pump is active.
4Use of energy by moving object
If the first pump is made controllable to optimize flow, then energy consumption can be reduced, but the control system complexity increases
Solution Approach 1:
The controllable first pump enables parameter changes in the hydraulic system by adjusting flow rate and pressure according to actual steering demands. The control system modifies pump operating parameters in real-time, reducing energy consumption by avoiding constant high-pressure operation while maintaining adequate steering assistance across varying vehicle speeds and steering conditions.
Data Source
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AI summary
The present disclosure relates to a power steering system (100) for a vehicle (1), the power steering system (100) comprising a power steering control system (140) configured to control the power steering system, (100) a first power steering pump (110A) configured to be driven by a propulsion source (2) of the vehicle (1), a second power steering pump (110B) configured to be driven by the rotation of the wheels (5) of the vehicle (1), wherein the first power steering pump (110A) is a controllable pump operatively connected to the power steering control system (140) and said power steering control system (140) is configured to control said first power steering pump (110A). The first and second power steering pump (110A, 110B) are connected to a common power steering fluid circuit (112) such that said first and second power steering pump (110A, 110b) can operate in parallel to simultaneously provide power steering assistance.