Clutch Protection via Torque Reduction
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Solution Overview
Problem
Current power transfer systems in four-wheel drive and all-wheel drive vehicles are prone to damage in scenarios where sudden differential speed occurs between the front and rear output shafts, leading to excessive torque and heat buildup in the multi-plate clutch, especially during simultaneous throttle and brake pedal activation on low friction surfaces.
Innovation Solution
A power transfer assembly with a transfer case control module (TCCM) that communicates with an engine control module (ECM) to reduce engine torque output when slip conditions are detected, thereby mitigating clutch damage and heat buildup by regulating torque distribution between the front and rear drivelines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transfer case clutch increases torque capacity to equalize wheel speeds during slip conditions, then the drive torque distribution is improved, but the clutch operating temperature increases excessively causing damage
Solution Approach 1:
The system applies preliminary anti-action by detecting slip conditions early and reducing engine torque output before the clutch temperature can rise to damaging levels. The control module monitors wheel speed differential and preemptively reduces torque demand, preventing the harmful thermal buildup that would otherwise occur during prolonged slip conditions.
Solution Approach 2:
The system converts the harmful effect of wheel slip into a beneficial control opportunity. By detecting the slip condition and interpreting it as a signal to reduce torque demand, the system transforms what would be a damaging scenario into a controlled operating state where the clutch is protected while still maintaining adequate traction control.
2Reliability
If the clutch actuator increases clutch engagement force to regulate torque distribution, then the torque distribution between front and rear drivelines is improved, but the clutch heat buildup increases causing damage
Solution Approach 1:
The system performs preliminary action by reducing engine torque output before excessive heat buildup occurs. The control module proactively adjusts the torque demand based on detected slip conditions, preventing the clutch from experiencing prolonged high-temperature operation that would lead to damage.
Solution Approach 2:
The system changes the torque parameter dynamically by reducing engine torque output in response to slip conditions. This parameter change reduces the energy dissipation in the clutch, thereby reducing heat buildup while maintaining adequate torque distribution control.
3Ease of operation
If the system allows simultaneous throttle and brake activation on low friction surfaces, then the driver's control input is respected, but the differential speed between front and rear shafts causes clutch damage
Solution Approach 1:
The system applies feedback by continuously monitoring wheel speed differential and using this information to adjust engine torque output. When the feedback indicates a slip condition (excessive differential speed), the control module reduces torque demand, thereby protecting the clutch while still allowing the driver's throttle and brake inputs to remain active.
Solution Approach 2:
The control module acts as an intermediary between the driver's control inputs and the clutch. It mediates the conflicting demands by reducing torque demand in response to slip conditions, thereby protecting the clutch from damage while still respecting the driver's operational inputs.
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 the risk of clutch damage and wheel slip by dynamically adjusting torque output based on detected slip conditions, enhancing vehicle stability and alerting the driver to potential issues, thus preventing overheating and damage to the multi-plate clutch.
Implementation Method 1
an actively-controlled multi-plate friction clutch selectively transmitting drive torque from the powertrain to a secondary driveline
Implementation Method 2
a power-operated clutch actuator regulating a magnitude of a clutch engagement force applied to the actively-controlled multi-plate friction clutch
Data Source
AI summary
A power transfer assembly for a motor vehicle includes a clutch protection system to prevent damage to an actively-controlled multi-plate mode clutch of the power transfer assembly. The clutch protection system includes a transfer case control module (TCCM) and an engine control module (ECM) configured to regulate the distribution of torque applied from an engine to front and rear output shafts of the power transfer assembly. The TCCM is in operable communication with the engine control module ECM, wherein TCCM is configured to detect slip in the actively-controlled multi-plate friction clutch and to communicate with the ECM to selectively reduce the output torque of the engine in response to detected slip.