Wet Clutch Lubricant Flow Control for Cooling and Flutter Prevention
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Solution Overview
Problem
Wet clutches in off-highway vehicles experience energy loss and premature degradation due to excessive lubricant flow beyond heat removal and gyroscopic imbalances causing clutch flutter, which affects efficiency and reliability.
Innovation Solution
A method and apparatus for controlling lubricant flow rate in wet clutches by determining the clutch state, temperature, and sump lubricant temperature to select appropriate maps for operating parameters, thereby optimizing lubricant flow rate and preventing clutch flutter through a lubricant volume pump and flow control devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling oil flow is continued beyond the time when excess heat has been removed from the clutch, then cooling capacity is maintained, but energy is wasted
Solution Approach 1:
The lubricant flow rate is dynamically adjusted based on real-time clutch state, temperature, and sump lubricant temperature. The system transitions from static continuous flow to dynamic variable flow, optimizing cooling capacity while minimizing energy consumption by adapting flow rate to actual thermal conditions.
Solution Approach 2:
The control system continuously monitors clutch state, clutch temperature, and sump lubricant temperature, using this feedback to determine the appropriate lubricant flow rate from pre-stored maps. This closed-loop control ensures cooling is provided only when and where needed, eliminating energy waste from excessive cooling.
2Loss of energy
If lubricant flow rate is reduced to save energy, then energy efficiency improves, but clutch cooling capacity may be insufficient
Solution Approach 1:
The system dynamically determines lubricant flow rate based on real-time thermal conditions and clutch state, ensuring sufficient cooling capacity is maintained while optimizing energy efficiency. The flow rate adapts to match actual cooling demands rather than operating at fixed high or low levels.
Solution Approach 2:
The control system selects from multiple pre-stored maps that define different flow rate characteristics based on operating conditions. By changing the operational parameters (selecting different maps based on clutch state and temperature conditions), the system optimizes the balance between cooling capacity and energy consumption for each specific operating scenario.
3Speed
If clutch plates rotate at opposite high speeds in disengaged state, then clutch responsiveness improves, but gyroscopic imbalance causes clutch flutter
Solution Approach 1:
Lubricant acts as an intermediary between the clutch plates, creating a fluid film that prevents direct contact and stabilizes the plates during high-speed rotation in disengaged state. The lubricant flow dampens gyroscopic imbalances and prevents clutch flutter, allowing high-speed operation without stability issues.
Solution Approach 2:
The system uses hydraulic lubricant flow to control clutch plate behavior during disengagement. By regulating lubricant flow rate and pressure, the system creates hydrodynamic effects that stabilize rotating plates and eliminate flutter, replacing mechanical contact-based stabilization with fluid-based stabilization.
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 solution improves the overall efficiency of the clutch by optimizing cooling capacity and preventing clutch flutter, reducing energy waste and extending the clutch's useful life by dynamically adjusting lubricant flow based on clutch states and temperatures.
Implementation Method 1
cooled lubricating oil flowing through a wet clutch assembly may also be used for cooling the clutch assembly
Implementation Method 2
The friction generates heat and excessive heat may cause premature clutch degradation
Implementation Method 3
Another source of energy loss in a disengaged friction clutch constitutes clutch plates touching
Data Source
AI summary
The present disclosure relates to a method and an apparatus for controlling a lubricant flow rate in a wet clutch. The method comprising: determining a clutch state as an open state, a closed state or a slipping state; determining a clutch temperature and a sump lubricant temperature; based at least on the clutch state, the clutch temperature and the sump lubricant temperature, selecting one out of a plurality of maps, wherein each map maps one or more operating parameters of the clutch on a target lubricant flow rate; determining a target lubricant flow rate based on the one or more operating parameters according to the selected map; and controlling a lubricant flow control device based on the determined target lubricant flow rate.