EV Gear Engagement Control for Misalignment and Disengagement
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Solution Overview
Problem
In electric vehicles, misalignment of engaging portions of the disk or parking lever with corresponding notches on the gear can cause damage, increased noise, and difficulty in disengagement, particularly in off-road vehicles, due to the lack of engine braking and high friction forces.
Innovation Solution
A method for shifting gears in electric vehicles using an engagement member with projections and receiving portions, controlled by an electric motor to align and engage/disengage gears through torque application in specific directions, reducing misalignment and friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dimension of the notches on the gears or the disk are increased to reduce the probability of misalignment and ease engagement, then the probability of misalignment is reduced and engagement is eased, but this leads to an increased space for the engaging portion to move within the notch, resulting in collisions between the engaging portions and the gear which can cause increased noise generation and wear on the transmission components
Solution Approach 1:
The motor controller applies torque to the gear in advance of engagement to rotate the gear and align the receiving portion with the engaging portion of the disk. This preliminary alignment action prevents misalignment collisions during engagement while allowing for smaller, more precise notch dimensions, thereby reducing noise and wear.
2Speed
If the gear or disk are misaligned and the operator attempts to rapidly accelerate the vehicle, then the vehicle acceleration is rapid, but the gear and disk may not engage and instead will repeatedly glance off one another, potentially causing damage to the gear and disk
Solution Approach 1:
Before the operator rapidly accelerates the vehicle, the motor controller pre-rotates the gear by applying torque to align the receiving portion with the engaging portion of the disk. This preliminary alignment ensures that when rapid acceleration occurs, the gear and disk are properly aligned and will engage successfully, preventing glancing collisions and damage.
3Strength
If the gear may exert substantial forces onto the disk or parking lever when the engaging portion of the disk or parking lever and the corresponding notches on the gear are engaged, then the gear engagement strength is high, but this impedes disengagement of the disk or parking lever, due to the increased friction between them
Solution Approach 1:
The patent replaces the traditional mechanical disengagement method (operator physically rocking the vehicle) with an electric motor system. The motor controller applies controlled torque to the gear to rotate it and reduce friction between the engaging portion and the gear, enabling easy disengagement while maintaining strong engagement during normal operation.
4Ease of operation
If the operator will need to physically rock the vehicle back and forth to create a window of sufficiently reduced friction between the disk or parking lever and gear which, in some larger off-road vehicles, is difficult or impossible to do, then the disengagement force can be reduced, but the vehicle operation complexity increases and in some cases becomes impossible
Solution Approach 1:
The patent replaces the complex mechanical disengagement procedure (physically rocking the vehicle back and forth) with a simple electronic control system. The motor controller automatically applies torque to the gear to reduce friction and enable disengagement, making the process easy and possible even in larger off-road vehicles where manual rocking would be difficult or impossible.
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
Enhances gear engagement reliability, reduces damage and noise, and simplifies disengagement by aligning gears efficiently, improving vehicle responsiveness and transmission performance.
Implementation Method 1
controlling the electric motor, by a motor controller, to apply a torque to the gear in a first direction
Implementation Method 2
biasing an engagement member of the transmission toward a gear of the transmission corresponding to the selected gear position
Implementation Method 3
the gear may exert substantial forces onto the disk or parking lever when the engaging portion of the disk or parking lever and the corresponding notches on the gear are engaged, for example when the vehicle is on an incline, impeding disengagement of the disk or parking lever, due to the increased friction between them
Data Source
AI summary
A method of shifting gears of an electric vehicle and the electric vehicle are disclosed. The electric vehicle includes an electric motor operatively connected to a transmission for propelling the electric vehicle. The method includes selecting a gear position and biasing an engagement member of the transmission toward a gear of the transmission corresponding to the selected gear position. The engagement member has an engaging portion, and the gear has a receiving portion. The method includes controlling the electric motor, by a motor controller, to apply a torque to the gear in a first direction and, in response to applying the torque, aligning the engaging portion and the receiving portion such that the engagement member is biased further toward the gear; and the engaging portion is received in the receiving portion to engage the engaging member with the gear.