Drivetrain Torque Pre-Positioning for Smooth Vehicle Drive-Off
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Solution Overview
Problem
Drivetrain shocks and clunks during vehicle acceleration, particularly in commercial vehicles, due to mechanical play in gears, lead to discomfort and component stress, which existing methods fail to adequately address.
Innovation Solution
A method involving a torque pulse applied to pre-position the drivetrain before vehicle movement, shifting gears from the 'push' to the 'traction' side, overcoming mechanical play without causing vehicle movement, using a controlled torque pulse to ensure smooth acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rapid torque build-up is applied to achieve spontaneous acceleration, then acceleration performance is improved, but drivetrain shocks and mechanical play are overcome causing clunks and jolts
Solution Approach 1:
A torque pulse is applied before the main acceleration torque to pre-position the drivetrain components. This preliminary action shifts gears from the push side to the traction side, eliminating mechanical play beforehand. The torque pulse has a controlled build-up rate that is lower than the main acceleration torque, preventing drivetrain shocks while still achieving spontaneous acceleration when the main torque is subsequently applied.
2Manufacturing precision
If torque is applied to overcome mechanical play in the drivetrain, then gear positioning is improved, but vehicle movement is triggered prematurely
Solution Approach 1:
The torque pulse is designed with dynamic characteristics including a controlled build-up rate and a duration that is limited. The build-up rate is specifically set to be lower than that of the main acceleration torque, and the pulse duration is controlled to ensure the drivetrain is repositioned without causing premature vehicle movement. This dynamic control allows precise gear positioning while maintaining proper movement timing.
3Productivity
If the torque pulse build-up rate is increased to reduce pre-positioning time, then productivity is improved, but drivetrain shocks may occur
Solution Approach 1:
The torque pulse parameters are optimized to achieve the best balance between pre-positioning time and shock prevention. The build-up rate is set to a specific value that is as high as possible without causing drivetrain shocks, and the duration is optimized to minimize pre-positioning time. These parameter changes allow the system to achieve rapid yet smooth drivetrain repositioning.
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
Pre-positioning the drivetrain gears on the traction side eliminates shocks and jerks, providing a comfortable and component-friendly start-up by minimizing mechanical play without additional energy transfer.
Implementation Method 1
introducing a torque pulse into the drivetrain while the vehicle is stationary
Data Source
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AI summary
The invention relates to a method for operating the drivetrain of a motor vehicle during acceleration, in particular for reducing drivetrain shocks during acceleration. The invention further relates to a control device for operating the drivetrain of a motor vehicle. The invention further relates to a motor vehicle, for example a commercial vehicle, with such a device. According to general principles of the invention, pre-positioning (S6) of the drivetrain before the motor vehicle starts moving is proposed by introducing a torque impulse into the drivetrain while the vehicle is stationary with the engine running and a gear engaged. In this way, undesirable drivetrain shocks during acceleration can be avoided or at least reduced.