Motor-Driven Gear Preload to Reduce Vehicle Gear Rattle
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Solution Overview
Problem
Gear rattle in power transmission paths due to backlash between tooth surfaces of gear trains, leading to an uncomfortable driving experience.
Innovation Solution
A vehicle driving apparatus with an electric motor, a first gear, and an actuator that moves a rotor to adjust its position relative to a stator, applying magnetic force to urge a first gear axially and push its tooth surface against a second gear, reducing backlash and gear rattle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If backlash is provided in gear trains, then ease of manufacture is improved, but gear rattle occurs leading to reduced driving comfort
Solution Approach 1:
The actuator moves the rotor axially in advance to apply magnetic force to the first gear, pre-compressing the tooth surface of the first gear against the tooth surface of the second gear before power transmission begins. This preliminary action eliminates backlash and prevents gear rattle from occurring in the first place.
Solution Approach 2:
The patent replaces traditional mechanical backlash adjustment mechanisms with a magnetic force-based system. The actuator generates magnetic force between the rotor and first gear, using electromagnetic interaction to apply axial compression force that eliminates backlash, thereby substituting complex mechanical adjustment systems with a more compact magnetic field-based solution.
2Object-affected harmful factors
If the rotor is moved closer to the first gear, then backlash is reduced and gear rattle is minimized, but the magnetic force required increases
Solution Approach 1:
The system dynamically adjusts the axial position of the rotor based on operating conditions. The actuator controls the degree of overlap between the rotor and first gear, allowing the magnetic force to be optimized in real-time. This dynamic adjustment enables the system to use minimal magnetic force while still achieving sufficient backlash reduction to eliminate gear rattle.
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
Reduces gear rattle by minimizing backlash in power transmission paths, enhancing driving comfort and efficiency.
Implementation Method 1
The first gear is urged in the axial direction due to a magnetic force applied between the rotor and the first gear
Data Source
AI summary
A vehicle driving apparatus includes: an electric motor including a rotor provided movably in an axial direction relative to a rotor shaft and a stator disposed on an outside of the rotor in a radial direction; a first gear provided movably in the axial direction relative to the rotor shaft and disposed so as to face an end face of the rotor; a power transmission path including a second gear engaged with the first gear and coupling the first gear and wheels to each other; and an actuator that moves the rotor to a first position and a second position. The rotor is moved to the second position by the actuator. The first gear is urged in the axial direction due to a magnetic force applied between the rotor and the first gear. A tooth surface of the first gear is pushed against a tooth surface of the second gear.