Augmented Braking Torque for Transmission NVH Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vehicle transmissions experience noise, vibration, and harshness (NVH) issues during shifts between modes due to gear lash, leading to undesirable sensations for the driver, which current solutions require operator intervention to mitigate.
Innovation Solution
A braking system that applies an augmented braking torque based on the transmission mode and driver request, with a calibratable rate, to reduce NVH during shifts, and includes a controller to manage braking torque based on vehicle speed, gear shifter position, and road grade.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gear teeth are engaged during transmission mode shifts, then power transmission is achieved, but gear lash causes noise, vibration, and harshness (NVH)
Solution Approach 1:
The braking system applies a braking torque to the drive shaft before and during the transmission mode shift to prevent the gear teeth from striking each other due to gear lash. This preliminary counter-action eliminates the relative motion that causes NVH while maintaining the engagement necessary for power transmission.
Solution Approach 2:
The controller commands the braking system to apply braking torque in advance of the transmission shift event, preparing the system to absorb gear lash impacts before they occur. This preliminary action ensures that the gear teeth remain engaged without experiencing harmful relative motion during the shift.
2Ease of operation
If braking torque is applied to reduce NVH during shifts, then operator satisfaction is improved, but vehicle control complexity increases
Solution Approach 1:
The controller continuously monitors transmission mode shift events and automatically adjusts the braking torque application accordingly. This feedback mechanism ensures that braking is applied only when necessary to reduce NVH during shifts, maintaining operator satisfaction while avoiding unnecessary complexity in normal operating conditions.
Solution Approach 2:
The braking control system automatically detects transmission shift events and applies the appropriate braking torque without requiring operator intervention. The system serves itself by monitoring its own operating conditions and making real-time adjustments to eliminate NVH, simplifying the operator's interaction while managing the control complexity internally.
3Object-affected harmful factors
If augmented braking torque is applied during transmission shifts, then NVH is reduced, but braking system energy consumption increases
Solution Approach 1:
The augmented braking torque is applied periodically only during transmission mode shift events rather than continuously. The controller detects shift events and applies braking torque only during these brief intervals, significantly reducing overall energy consumption while still effectively eliminating NVH when it would occur.
Solution Approach 2:
The braking system applies excessive braking torque only partially during the brief duration of transmission shifts. This partial application of excessive force is sufficient to eliminate gear lash impacts and NVH, while the limited duration and frequency of application keep overall energy consumption minimal.
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 solution effectively reduces NVH during transmission shifts without requiring operator intervention, enhancing operator satisfaction by maintaining the vehicle stationary and smoothly transitioning between modes.
Implementation Method 1
a braking system configured to provide braking torque to traction wheels
Data Source
AI summary
A method of controlling a vehicle includes, in response to vehicle speed being approximately zero and a driver braking torque request being greater than a park interlock threshold, commanding vehicle brakes to provide an augmented braking torque. The augmented braking torque has a magnitude that is greater than the magnitude of the braking torque request. The braking torque returns to the level of the driver braking torque request following completion of a gear shift event.