Electric Vehicle Powertrain Torque Jog and Fluid Actuator Gear Shift
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Solution Overview
Problem
Current powertrain control systems in electric vehicles face inefficiencies during gear shifting, particularly in transitioning between gear ratios, due to delays or failures in disengaging from the current gear, leading to resistive forces and potential operational issues.
Innovation Solution
The implementation of a torque jog algorithm in the electric motor and a fluid-activated actuator to assist gear shifting, where the torque jog induces a momentary fluctuation in torque output and a burst of pressurized air is used to supplement the actuator's spring force, ensuring timely disengagement from the current gear and smooth transition to the neutral position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional gear shift control system is used in an electric vehicle, then the system structure remains simple, but the gear disengagement is delayed or fails, causing resistive forces and operational issues
Solution Approach 1:
The control system initiates a torque jog (momentary torque fluctuation) before and during the gear shift event to actively assist the gearbox in disengaging from the current gear. This preliminary and concurrent action ensures the gear disengages timely and reliably, preventing the delays and failures experienced with conventional control systems.
Solution Approach 2:
The system dynamically adjusts motor torque during the gear shift event by implementing a torque jog algorithm that creates controlled torque fluctuations. This dynamic torque modulation optimizes the disengagement process, ensuring smooth and reliable gear transitions while adapting to the real-time mechanical state of the gearbox.
2Speed
If no torque fluctuation is applied during gear shift, then the motor operates smoothly, but the gearbox experiences delayed disengagement and increased drag torque
Solution Approach 1:
The torque jog algorithm induces controlled mechanical vibrations in the motor output shaft through momentary torque fluctuations. These vibrations help break the static friction and drag torque in the gearbox during gear transitions, enabling faster and smoother disengagement without causing harmful oscillations in normal operation.
Solution Approach 2:
The control system applies periodic torque jogs at specific moments during the gear shift event. These periodic torque fluctuations occur only during the brief transition period, providing the necessary assistance for rapid disengagement while maintaining smooth motor operation during steady-state conditions.
3Productivity
If a fluid-activated actuator is used to assist gear shifting, then the gear disengagement efficiency is enhanced, but the system complexity and fluid management requirements increase
Solution Approach 1:
The system employs a fluid-activated actuator that uses pressurized fluid (pneumatic or hydraulic) to assist the gear shifting process. The fluid pressure provides additional force to the actuator mechanism, enhancing the disengagement efficiency and ensuring reliable gear transitions, particularly under high-load conditions where mechanical force alone may be insufficient.
Solution Approach 2:
The control system merges multiple assistance mechanisms into a unified gear shift process: electrical torque jog from the motor controller, mechanical actuation from the actuator mechanism, and fluid pressure assistance from the pneumatic/hydraulic system. This combination of multiple forces working together ensures robust and efficient gear disengagement.
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
This approach minimizes drag torque, reduces motor inertia, and enhances gear disengagement efficiency, facilitating smoother and more reliable gear shifts, thereby improving the overall performance and efficiency of the powertrain.
Implementation Method 1
one or more electric motors serve as the power source... An inverter coupled to the motors direct current to the motors to produce torque
Implementation Method 2
a fluid-activated actuator configured to perform a gear shift in the gearbox... selective activation of (a) a torque jog in the electric motor to assist with the gear shift, and (b) pressurized fluid into the actuator to assist with the gear shift
Data Source
AI summary
The power train of an electric vehicle includes an electric motor and a gearbox coupling the electric motor to a drive wheel. A controller may be configured to initiate a gear shift in the gearbox, and activate one or both of (a) a torque jog in electric motor, or (b) a burst of a pressurized fluid in an actuator to assist with the gear shift.