EV Drivetrain Gearbox Shifting Without Synchronization Rings
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Solution Overview
Problem
Electric vehicle drivetrains face challenges in powering accessories when the vehicle is stationary, as existing systems require the main electric motor to operate accessories, leading to inefficiency and space constraints, and synchronization issues during gear shifting in electric vehicle drivetrains without synchronization rings, which can cause damage and drivability problems.
Innovation Solution
A hydraulically operated gearbox system for electric vehicle drivetrains that uses a support rod and pistons fluidically connected to hydraulic fluid passages to shift gears, allowing the motor speed to be synchronized with wheel speed by changing the rotational speed of the electric motor, eliminating the need for synchronization rings and enabling efficient accessory power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronization rings are used in the gearbox to match rotation speed during shifting, then the meshing of gears is improved, but the weight and complexity of the gearbox increases
Solution Approach 1:
The patent removes synchronization rings from the gearbox system entirely. Instead of using mechanical synchronization components, the system relies on the electric motor's ability to rapidly adjust its rotational speed to match wheel speed during gear shifts, thereby eliminating the need for synchronization rings and reducing gearbox complexity and weight.
Solution Approach 2:
The patent replaces the mechanical synchronization system (synchronization rings) with an electrical control system. The electric motor controller adjusts the motor's rotational speed to achieve synchronization during gear shifts, substituting mechanical components with electrical control to reduce complexity.
2Power
If the main electric motor is used to power accessories when the vehicle is stationary, then accessory power requirements are met, but the drive motor efficiency decreases and space constraints are worsened
Solution Approach 1:
The patent segments the power delivery function by introducing a two-speed gearbox that can operate in different modes. During vehicle operation, the system uses drive gears for propulsion. When stationary, the system shifts to neutral gear, allowing the motor to continue running efficiently while powering accessories through the gearbox's auxiliary output, thus separating propulsion and accessory power functions.
Solution Approach 2:
The patent implements a dynamic gearbox system with two speeds and multiple operating modes. The gearbox can dynamically shift between drive gears for motion and neutral gear for stationary operation, allowing the system to adapt its configuration based on whether the vehicle is moving or stationary, thereby optimizing motor efficiency in both scenarios.
3Speed
If the gearbox is shifted from one drive gear to another without synchronizing motor speed with wheel speed, then shifting speed is improved, but gear engagement reliability decreases and damage may occur
Solution Approach 1:
The patent implements a feedback control system where the controller continuously monitors both motor speed and wheel speed. During gear shift operations, the controller adjusts the motor speed based on feedback from speed sensors to ensure proper synchronization with wheel speed before engagement, thereby maintaining reliability while enabling fast shifts.
Solution Approach 2:
The patent performs preliminary speed synchronization by adjusting the motor speed to match the required engagement speed before the actual gear engagement occurs. The controller pre-adjusts the motor rotational speed to the appropriate level for the target gear, ensuring smooth and reliable engagement before the shift is completed.
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 gearbox system allows for efficient power management of accessories when the vehicle is stationary and prevents gear damage by synchronizing motor and wheel speeds during shifting, enhancing drivetrain efficiency and reliability.
Implementation Method 1
pressurized hydraulic fluid forces the first piston and the second piston against the support rod
Implementation Method 2
Electric motors are used on electric vehicles for propulsion
Data Source
AI summary
Described herein is a gearbox for an electric vehicle drivetrain unit comprising a gearbox enclosure, a support rod, a first piston, a second piston, and various hydraulic fluid passages. The support rod extends into the gearbox enclosure and at least partially protrudes/extends into the first and second pistons. The first piston, second piston, and support rod are fluidically connected with the hydraulic fluid passages such that when the gearbox is in a neutral gear, pressurized hydraulic fluid forces the first piston and the second piston against the support rod. When the gearbox is in a first gear, pressurized hydraulic fluid forces the support rod against the gearbox enclosure either directly or through the first piston. When the gearbox is in a second gear, pressurized hydraulic fluid forces the support rod against the gearbox enclosure directly or through the second piston. Also described are electric vehicles and shifting methods.