Torque Converter Refill Using Clutch-Apply Fluid Path
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Solution Overview
Problem
Automatic transmissions face inefficiencies due to torque converter drain-down, leading to reduced torque transfer and unsatisfactory driving experiences, as current systems take too long to refill the torque converter, often requiring 20 seconds or more.
Innovation Solution
Implementing a method where a controller, responsive to engine-off time exceeding a threshold and parameters indicative of vehicle departure, uses the clutch-apply fluid path to quickly refill the torque converter with pressurized fluid, reducing refill times from 13 seconds to 2 seconds by utilizing higher flow rates typically reserved for clutch engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the torque converter is refilled using the conventional fluid path after drain-down, then the system maintains simple fluid routing, but the refill time exceeds 20 seconds causing delayed torque transfer and unsatisfactory driving experience
Solution Approach 1:
The system pre-pressurizes the clutch-apply fluid path and positions fluid ready for rapid delivery before drain-down occurs. When refill is needed, the pre-positioned pressurized fluid immediately flows through the clutch-apply path into the torque converter, reducing refill time from 20+ seconds to under 2 seconds without requiring permanent structural changes to the fluid routing system
Solution Approach 2:
The system dynamically switches between using the clutch-apply fluid path for rapid refill and the conventional fluid path for normal operation. A controller activates the clutch-apply path only when refill is needed (detected via engine-off time threshold and departure parameters), allowing the system to adapt its fluid routing configuration based on operational requirements rather than maintaining a fixed complex structure
2Productivity
If the clutch-apply fluid path is used for refilling, then refill speed increases from 13 seconds to 2 seconds, but the system requires additional control logic to manage fluid path selection
Solution Approach 1:
The system changes the flow rate parameter by switching to the clutch-apply fluid path, which is designed to deliver higher flow rates for clutch engagement. The controller monitors engine-off time and departure parameters to determine when to activate this high-flow path, temporarily changing the flow rate parameter from normal operation levels to maximum refill levels, achieving 2-second refill times without permanently complexifying the control system
3Loss of energy
If the torque converter remains drained for extended periods, then fluid leakage to the sump is minimized, but torque transfer efficiency deteriorates and driving performance suffers
Solution Approach 1:
The system performs preliminary refilling action by detecting when the engine has been off longer than a threshold time and departure parameters are present. It proactively refills the torque converter before the driver attempts to propel the vehicle, ensuring sufficient fluid is present to maintain torque transfer reliability from the moment driving begins, rather than waiting for torque transfer problems to manifest
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 significantly reduces torque-converter refill times, ensuring sufficient fluid coupling and improving the driving experience by minimizing the likelihood of driver attempts to propel the vehicle before the torque converter is refilled.
Implementation Method 1
a device configured to generate line pressure, and at least one fluid path connecting the device in fluid communication with the torque converter
Implementation Method 2
The device may be a transmission pump or an accumulator
Data Source
AI summary
A vehicle includes a transmission having a torque converter, a device configured to generate line pressure, and at least one fluid path connecting the device in fluid communication with the torque converter. A controller is programmed to, responsive to an engine-off time exceeding a threshold and a parameter indicative of departure being present, command the device to generate line pressure so that fluid is supplied to the torque converter. The device may be a transmission pump or an accumulator.