Steer-By-Wire Worm Gear Rotation Limit for Steering Feel

Solution Overview

Problem

Steer-by-wire type steering systems lack mechanical connections between the steering shaft and wheels, leading to a deterioration in steering feel due to the absence of weight feel caused by friction and jamming, and there is a need to prevent the steering wheel from being turned beyond a maximum rotation angle without increasing the size and weight of the motor.

Innovation Solution

A steer-by-wire type steering apparatus that includes a worm wheel coupled to a steering shaft and a worm shaft with a worm gear, featuring a first rotatable worm gear portion and a second non-rotatable worm gear portion. This gear structure prevents the steering shaft from mechanical rotation when the steering wheel reaches a predetermined rotation angle, thereby limiting the steering wheel's turn without boosting the motor's size and weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a motor is used to apply torque to the steering shaft to prevent over-rotation, then the steering wheel can be limited within a maximum rotation angle, but the motor size and weight must be increased to generate high torque

Engineering Contradiction:

Improvesteering wheel rotation limitVSAvoidmotor weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces the motor-based torque application system with a mechanical gear structure (worm gear and gear mesh). The worm gear engages with the gear at the maximum rotation angle to mechanically prevent further rotation, eliminating the need for a high-torque motor and reducing overall system weight.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention extracts the rotation limiting function from the motor system and implements it separately through a dedicated gear structure. This separation allows the motor to maintain its original size while the gear structure handles the rotation limitation independently.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If a motor is used to apply torque to the steering shaft to prevent over-rotation, then the steering wheel can be limited within a maximum rotation angle, but the cost increases due to larger motor specifications

Engineering Contradiction:

Improvesteering wheel rotation limitVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the motor-based torque application system with a mechanical gear structure (worm gear and gear mesh). The worm gear engages with the gear at the maximum rotation angle to mechanically prevent further rotation, eliminating the need for a high-torque motor and reducing overall system weight.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a motor is used to apply torque to the steering shaft to prevent over-rotation, then the steering wheel can be limited within a maximum rotation angle, but the package size increases

Engineering Contradiction:

Improvesteering wheel rotation limitVSAvoidmotor size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent replaces the motor-based torque application system with a mechanical gear structure (worm gear and gear mesh). The worm gear engages with the gear at the maximum rotation angle to mechanically prevent further rotation, eliminating the need for a high-torque motor and reducing overall system weight.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Weight of moving object

If steer-by-wire system is used without mechanical connection, then vehicle weight is reduced and fuel efficiency is improved, but steering feel deteriorates due to absence of weight feel from friction and jamming

Engineering Contradiction:

Improvevehicle weightVSAvoidsteering feel

Core Design Contradiction:

Weight of moving objectVSEase of operation

Solution Approach 1:

The patent introduces a mechanical gear structure (worm gear and gear mesh) as an intermediary component in the steer-by-wire system. This mechanical connection provides weight feel and friction feedback to the driver while maintaining the overall electrical control architecture, thus improving steering feel without compromising the weight reduction benefits.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution effectively limits the steering wheel's rotation within a predetermined angle without increasing the motor's size or weight, enhancing cost, package, and operational efficiency while improving steering feel by preventing excessive steering wheel rotation.

Implementation Method 1

a worm shaft that is axially slidable, and includes a worm gear including a first worm gear portion rotatable in a situation of engaging the gear and a second worm gear portion not rotatable in a situation of engaging the gear

Methodology Applied

Scientific EffectMechanical Advantage: Mechanical Advantage

Data Source

PatentUS12263895B2Steer-by-wire type steering apparatus

Publication Date: 2025.04.01 HL MANDO CORP

AI summary

The present embodiments relate to a steer-by-wire type steering apparatus, which prevents a steering shaft from mechanically rotating by means of a gear structure when a driver turns the steering wheel at the maximum rotation angle or greater, so as to enable efficient limiting of the steering wheel operation of the driver to be within a maximum rotation angle without increasing the size, the weight and the like of a motor for transmitting torque to the steering shaft and the like, and to be advantageous with respect to production costs, packaging and the like.