Torque Converter Impeller Speed Control for Hybrid Vehicle Launch
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Solution Overview
Problem
Hybrid vehicles face challenges in achieving optimal acceleration and efficiency during launch due to wheel slip and insufficient torque delivery, which is affected by road conditions, tires, and ambient climate, leading to subpar performance and energy wastage.
Innovation Solution
Adjusting the speed of the torque converter impeller by contemporaneously applying the brake and accelerator pedals to optimize engine and electric machine torque delivery, ensuring maximum powertrain torque is provided to the wheels quickly, and using the electric machine to manage wheel slip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high torque is applied to wheels during vehicle launch, then vehicle acceleration is improved, but wheel slip occurs causing energy waste
Solution Approach 1:
The system performs preliminary actions by simultaneously applying the brake pedal before launch to pre-rotate the torque converter impeller to an optimal speed, and pre-positioning the engine and electric machine to deliver maximum torque at the moment of launch, thereby eliminating the need for torque buildup time and preventing wheel slip
Solution Approach 2:
The controller continuously monitors wheel slip conditions and dynamically adjusts the torque converter impeller speed and electric machine torque contribution in real-time to maintain optimal traction and prevent energy waste from excessive wheel slip
2Loss of time
If torque converter impeller speed is increased before launch, then powertrain torque delivery time is reduced, but energy consumption increases
Solution Approach 1:
The system pre-rotates the torque converter impeller to an optimal speed before launch by simultaneously applying the brake pedal, which stores kinetic energy in the impeller rotation. This preliminary action eliminates the torque buildup delay during launch, allowing immediate torque delivery to the wheels without requiring excessive energy input during the actual acceleration phase
3Speed
If electric machine torque is increased to prevent wheel slip, then vehicle acceleration is maintained, but powertrain complexity increases
Solution Approach 1:
The electric machine serves multiple functions: it provides torque addition to the engine during launch, acts as a generator to convert excess engine torque to electrical power when wheel slip occurs, and functions as a motor to increase wheel torque when engine torque is insufficient. This multi-functionality allows a single component to address multiple performance requirements without adding additional hardware complexity
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
Improves vehicle acceleration and efficiency during high-performance launches by optimizing torque delivery and minimizing wheel slip, resulting in enhanced acceleration and improved powertrain efficiency.
Implementation Method 1
adjusting speed of a torque converter impeller from a first speed to a second speed
Implementation Method 2
an electric machine may convert a portion of engine output torque to electrical power, thereby reducing an amount of power lost to wheel slip
Data Source
AI summary
Systems and methods for launching a hybrid vehicle that includes a motor/generator and an automatic transmission with a torque converter are described. The systems and methods may permit improved vehicle acceleration to enhance hybrid vehicle performance during specific vehicle launch conditions. The launch conditions may be established based on brake pedal position and accelerator pedal position.