Multi-mode Transmission Torque Control for Driveline Growl
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Solution Overview
Problem
Powertrain systems with multiple torque-generative devices face challenges in managing torque transfer to avoid undesirable operating regions that cause driveline growl, a condition characterized by objectionable noise and vibration, especially during vehicle creep and launch operations.
Innovation Solution
The system identifies and avoids the undesirable input/output torque region associated with driveline growl by controlling motor torque and mechanical braking torque in response to operator commands, using a multi-mode transmission with electric torque machines and hydraulic clutches to minimize power loss and maintain optimal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If motor torque is controlled to avoid undesirable operating regions, then driveline noise and vibration are reduced, but system complexity increases due to coordinated control of multiple torque-generative devices
Solution Approach 1:
The control system dynamically adjusts the operational state of the multi-mode transmission and torque machines based on real-time operating conditions. The controller continuously monitors torque requests and transmission state to determine optimal torque distribution, enabling the system to adaptively avoid undesirable operating regions while maintaining simplicity through rule-based decision logic.
Solution Approach 2:
The system changes operational parameters (torque machine torque output, transmission gear state) to transition out of undesirable operating regions. By monitoring the current operating point and adjusting torque parameters, the controller effectively eliminates driveline growl conditions without requiring complex mechanical modifications.
2Productivity
If multiple torque-generative devices are used to manage torque transfer, then vehicle performance and fuel economy are improved, but undesirable operating regions causing driveline growl are more likely to occur
Solution Approach 1:
The control system employs feedback by continuously monitoring the operating state of the multi-mode transmission and the torque output of torque machines. Based on this feedback, the controller determines whether the system is approaching or entering undesirable operating regions and adjusts torque distribution accordingly, allowing the performance benefits of multiple torque-generative devices to be maintained while avoiding driveline growl.
Solution Approach 2:
The controller acts as an intermediary that coordinates the torque output between the engine and torque machines. By mediating the torque distribution and transmission state selection, the system optimizes performance and fuel economy while preventing the combination of torques from entering the undesirable operating region that causes driveline growl.
3Object-affected harmful factors
If mechanical braking torque is applied to counteract driveline torque, then driveline growl is avoided, but energy loss increases
Solution Approach 1:
The system substitutes mechanical braking with electrical torque control from the torque machines. Instead of applying mechanical brake torque to counteract driveline torque, the controller adjusts the electrical torque output of the torque machines to achieve the same effect, thereby avoiding driveline growl while minimizing energy loss through regenerative braking capabilities.
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 effectively reduces driveline noise and vibration, allowing for efficient torque management during creep and launch conditions while minimizing energy loss and maintaining vehicle performance.
Implementation Method 1
The torque machines may transform vehicle kinetic energy transferred through the vehicle driveline to electrical energy that is storable in an electrical energy storage device in what is referred to as a regenerative operation.
Implementation Method 2
an internal combustion engine in an ON state generating an input torque
Data Source
AI summary
A vehicle includes an internal combustion engine coupled to an input member of a multi-mode transmission configured to transfer torque to an output member coupled to a ground wheel with the internal combustion engine in an ON state generating an input torque. A method for controlling the vehicle includes identifying an undesirable operating region including an input/output torque region for operating the multi-mode transmission. In response to an operator request for creep torque, motor torque is controlled from a torque machine coupled to the multi-mode transmission such that the multi-mode transmission is operating outside the undesirable operating region while a mechanical braking torque to the ground wheel is coincidentally controlled in response to an operator-commanded braking, the input torque from the engine, and the motor torque from the torque machine.