Hybrid Power Steering Control for Energy Reduction

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Solution Overview

Problem

Existing power steering systems in road vehicles consume excessive power due to simultaneous operation of electro-hydraulic and electric power steering subsystems, especially at low vehicle speeds where higher torque is required, leading to inefficient energy use.

Innovation Solution

Implement a control system that activates and deactivates the electro-hydraulic power steering subsystem based on vehicle speed and torque readings, switching to electric power steering alone at higher speeds and adjusting hydraulic motor rotational speed according to torque thresholds to minimize power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If both EHPS and EPS subsystems operate simultaneously, then steering assistance is maximized, but power consumption increases excessively

Engineering Contradiction:

Improvesteering assistance forceVSAvoidpower consumption

Core Design Contradiction:

ForceVSUse of energy by moving object

Solution Approach 1:

The system dynamically switches between EHPS and EPS subsystems based on real-time vehicle speed detection. The control system activates EHPS only when vehicle speed is below a predetermined threshold and switches to EPS alone when speed exceeds the threshold, optimizing power consumption while maintaining steering assistance performance across different operating conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the operational parameter of subsystem activation based on vehicle speed. By using speed as a control parameter, the system determines which subsystem(s) to activate, thereby adjusting power consumption levels to match the actual steering assistance needs at different speeds

Inventive Principle:

Principle #35Parameter changes

2Force

If EHPS subsystem operates at high rotational speed, then torque output is maximized, but power consumption increases

Engineering Contradiction:

Improvetorque outputVSAvoidpower consumption

Core Design Contradiction:

ForceVSUse of energy by moving object

Solution Approach 1:

The system applies partial action by activating EHPS only when necessary (vehicle speed below threshold) rather than continuously. Additionally, the hydraulic motor rotational speed is adjusted based on torque requirements, using only the necessary level of assistance needed at each moment rather than maximum capacity continuously

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The control system receives torque readings from a torque sensor and uses this feedback to adjust the hydraulic motor's rotational speed. When torque demand is high, the motor rotates faster to provide adequate assistance; when torque demand is low, the motor rotates slower, reducing power consumption while maintaining sufficient steering support

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS10518802B2Method for controlling a power steering system of a road vehicle

Publication Date: 2019.12.31 AUTOMOTIVE RES & TESTING CENT

AI summary

A method for controlling a power steering system of a road vehicle includes: after the road vehicle is started, activating only an EPS subsystem; afterward, activating an EHPS subsystem when a speed of the road vehicle is not higher than a predetermined speed threshold; once the EHPS subsystem is activated, controlling the hydraulic motor of the EHPS subsystem to rotate at a rotational speed lower than a pre-set rotational speed when a torque applied to a steering column is smaller than a predetermined torque threshold.