Torque Converter Thrust Path for Axial Displacement Control
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Solution Overview
Problem
Existing torque converters with lockup clutches face challenges in precisely controlling the 'liftoff' or axial displacement of the turbine piston, which can lead to imprecise clutch engagement due to hydrodynamic forces, especially when the operating conditions are not optimally controlled.
Innovation Solution
The torque converter design incorporates a friction material ring attached to the turbine or impeller shell radial walls, a damper spring system with integrally formed drive tabs, and a bushing with a circumferential and radial portion to transmit thrust forces effectively, limiting axial displacement and preventing metal-on-metal contact, thereby enhancing clutch engagement characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lockup clutch is incorporated in the torque converter, then clutch engagement can be achieved, but imprecise clutch engagement occurs due to uncontrolled hydrodynamic forces causing turbine piston axial displacement
Solution Approach 1:
A thrust path comprising a pusher plate, reaction plate, and thrust springs is introduced as an intermediary mechanical structure between the turbine piston and the housing. This thrust path mediates the axial forces, preventing uncontrolled displacement of the turbine piston and enabling precise clutch engagement by providing a defined mechanical constraint against hydrodynamic forces
Solution Approach 2:
Thrust springs are pre-installed in the thrust path to provide beforehand cushioning and force control. These springs are positioned to counteract hydrodynamic forces before they can cause excessive axial displacement, ensuring the turbine piston remains within precise engagement limits during operation
2Reliability
If friction material rings are added to the radial walls, then clutch engagement precision is improved, but device complexity increases
Solution Approach 1:
Friction material rings are merged with the existing radial wall structures of the impeller shell and turbine shell. Rather than adding separate complex engagement mechanisms, the friction material is integrated into the radial surfaces that already exist in the torque converter, improving clutch engagement precision while minimizing additional component complexity
3Reliability
If a bushing with circumferential and radial portions is installed, then metal-on-metal contact is prevented, but manufacturing complexity increases
Solution Approach 1:
A bushing with circumferential and radial portions is installed as an intermediary element between the turbine shell and the thrust path components. This bushing prevents direct metal-on-metal contact by providing a compliant interface that absorbs wear and reduces friction, thereby protecting the turbine shell and thrust path components while managing the manufacturing complexity through a standardized component design
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 design effectively limits axial displacement of the turbine piston, improves clutch engagement precision, and reduces torsional vibrations by isolating engine vibrations from the transmission, ensuring reliable operation by bypassing the fluid circuit during clutch engagement.
Implementation Method 1
a friction material ring fixedly attached to the turbine shell radial wall or the impeller shell radial wall
Implementation Method 2
the first damper spring is engaged with the turbine shell and arranged for isolating torsional vibrations from a transmission input shaft
Implementation Method 3
a bushing with a circumferential portion disposed within a circumferential bore of the turbine shell and a radial portion disposed between the turbine shell and the damper hub
Data Source
AI summary
A torque converter includes a torus with an impeller and a turbine having respective shells, a cover shell, and a first damper plate. The impeller shell has a radial wall disposed radially outside of the torus and the turbine shell has a radial wall arranged for frictionally engaging the impeller shell radial wall. The cover shell has a radial wall and the first damper plate has a radial wall for transmitting a turbine shell thrust force to the cover shell radial wall. In an example embodiment, the torque converter includes a friction material ring fixedly attached to the turbine shell radial wall or the impeller shell radial wall. In some example embodiments, the torque converter includes a friction material ring fixedly attached to the cover shell radial wall or the first damper plate radial wall.