Electric Power Steering Tow Mode for Flat Tow Stability

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Solution Overview

Problem

Newer vehicles with electric power steering systems lack the hydraulic damping necessary for stability during flat towing, posing safety concerns as existing solutions are not applicable to these vehicles.

Innovation Solution

The system employs an electric power steering system with a tow mode, enabled by a supplemental fuse and transfer case status signal, allowing the power steering controller to operate in a 'mute' mode that provides damping to the towed vehicle by directly powering the system from the battery, bypassing the vehicle's power system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electric power steering system is used in newer vehicles, then steering precision and control are improved, but hydraulic damping and stability during flat towing are lost

Engineering Contradiction:

Improvesteering precisionVSAvoidstability during flat towing

Core Design Contradiction:

Measurement precisionVSStability of the object's composition

Solution Approach 1:

The system changes the operational parameters of the electric power steering motor by switching between different control modes (normal driving mode vs. tow mode). In tow mode, the motor operates as a damping device by providing resistive torque to counteract steering inputs, thereby stabilizing the towed vehicle while maintaining the precision benefits of electric steering

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If hydraulic steering system is used, then damping and stability during towing are provided, but applicability to newer vehicles with electric power steering is limited

Engineering Contradiction:

Improvedamping and stabilityVSAvoidapplicability to electric power steering vehicles

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The invention replaces the hydraulic damping mechanism with an electrical control system. The electric power steering motor, controlled by a microprocessor, provides damping forces through electrical signals based on inputs from sensors and vehicle state information, thereby achieving hydraulic-like stability in electric power steering vehicles

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Stability of the object's composition

If supplemental fuse is installed to power electric power steering system during towing, then stability is improved, but system complexity increases

Engineering Contradiction:

Improvetowing stabilityVSAvoidsystem complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The system uses existing vehicle components (electric power steering motor, microprocessor, sensors, battery) to provide towing stability without requiring additional mechanical damping devices. The supplemental fuse simply enables power delivery to the existing electric power steering system, allowing it to self-regulate and provide damping through software control

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS11845497B2Method and system for flat tow stabilization of a vehicle using electrical power steering

Publication Date: 2023.12.19 FCA US LLC

AI summary

A flat towed vehicle includes a battery and wheels and a supplemental fuse. A transfer case generates a transfer case status signal an electric power steering system coupled to the wheels and the battery through the supplemental fuse. The electrical power steering system has a tow mode and a driven mode. The electric power steering system enters the tow mode when the supplement fuse communicates battery power to the electrical power steering system and the transfer case status signal corresponding to a neutral position.