Locking Piston Axial Displacement in Hydrokinetic Torque Coupling
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Solution Overview
Problem
Hydrokinetic torque-coupling devices with lock-up clutches experience premature disengagement due to axial forces generated by transmission fluid, especially during downhill driving, leading to unintended disengagement of the lock-up clutch.
Innovation Solution
A hydrokinetic torque-coupling device with a torsional vibration damper and a locking piston that is non-rotatably connected to the input member of the damper, allowing axial displacement while maintaining torque transmission, thereby enhancing the stability of the lock-up clutch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a lock-up clutch is used to mechanically couple the driving and driven shafts, then torque transmission efficiency is improved, but the lock-up clutch may prematurely disengage due to axial forces generated by transmission fluid during coasting conditions
Solution Approach 1:
A turbine piston is introduced as an intermediary component between the lock-up clutch and the torque converter turbine. The piston has a first end that receives hydraulic pressure from the torque converter and a second end that transmits force to the lock-up clutch. This intermediary allows the system to maintain lock-up engagement by using hydraulic pressure to counteract axial forces that would otherwise cause premature disengagement, thereby improving reliability while preserving torque transmission efficiency.
2Ease of operation
If the turbine piston is allowed to move axially to engage and disengage the lock-up clutch, then operational flexibility is improved, but axial displacement causes premature disengagement under certain conditions
Solution Approach 1:
The system uses hydraulic pressure as a feedback mechanism to control the axial position of the turbine piston. Pressure sensors or pressure-dependent valves monitor the hydraulic conditions in the torque converter and automatically adjust the piston position to maintain lock-up engagement when appropriate. This feedback control ensures that the lock-up clutch remains engaged during coasting conditions by maintaining sufficient hydraulic pressure to counteract axial separation forces, thereby improving reliability without sacrificing operational flexibility.
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 premature disengagement of the lock-up clutch, ensuring consistent torque transmission and improving the performance and reliability of hydrokinetic torque-coupling devices under various driving conditions.
Implementation Method 1
a plurality of circumferentially acting elastic members, and an output member elastically coupled to the input member through the elastic members
Implementation Method 2
selectively frictionally engage the locking piston against the engagement surface of the casing in lock-up mode
Data Source
AI summary
A hydrokinetic torque-coupling device features a casing rotatable about a rotational axis and having an engagement surface, a torque converter including an impeller wheel and a turbine wheel, a locking piston including a piston body and a damper assembly. The piston body has a front surface axially facing the engagement surface of the casing. The locking piston is axially moveable along the rotational axis to and from the engagement surface of the casing to selectively engage the locking piston against the engagement surface of the casing in a lock-up mode. The damper assembly comprises an input member rotatable about the rotational axis and non-moveably attached to the turbine wheel, circumferentially acting elastic members and an output member elastically coupled to the input member trough the elastic members. The locking piston is non-rotatably connected to and axially moveable relative to the input member of the torsional vibration damper.