Lock-up clutch dual-diameter friction interface
Solution Overview
Problem
Conventional lock-up clutches in torque converters have limited torque transfer capacity due to the interaction between friction members, which is restricted by the available fluid pressure, and often result in reduced efficiency and increased complexity and cost.
Innovation Solution
The lock-up clutch assembly features an annular piston with seal members at opposite diameters, increasing the effective area for fluid pressure application, pressing annular friction disks and plates together to enhance torque transfer capacity without increasing fluid pressure, and includes a splined coupling for smooth operation, reducing complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional lock-up clutch design is used with limited fluid pressure, then the structure is simpler, but the torque transfer capacity is limited
Solution Approach 1:
The patent transitions from a single-diameter friction interface to a dual-diameter friction interface, utilizing both an inner friction surface and an outer friction surface. This dimensional expansion allows the clutch to generate higher torque capacity by distributing friction forces across two distinct radial locations, effectively solving the torque capacity limitation without requiring a complete redesign of the clutch architecture.
Solution Approach 2:
The friction interface is segmented into multiple independent surfaces: an inner friction surface and an outer friction surface, each capable of transmitting torque independently. This segmentation allows the clutch to utilize the available fluid pressure more effectively across different radial zones, increasing overall torque capacity while maintaining the basic clutch structure.
2Strength
If fluid pressure is increased to improve torque capacity, then torque transfer capacity increases, but the available fluid pressure from the torque converter is limited
Solution Approach 1:
Instead of increasing pressure in a single-diameter system, the patent expands the friction interface to dual diameters, effectively distributing the torque transmission across a larger radial span. This allows the same limited fluid pressure to generate higher total torque by acting on two separate friction surfaces with different effective areas.
Solution Approach 2:
The patent combines the torque transmission functions of an inner friction surface and an outer friction surface into a unified clutch engagement system. Both surfaces work simultaneously under the same fluid pressure, merging their torque capacities to achieve a total torque capacity that exceeds what a single surface could provide at the same pressure level.
3Strength
If more friction members are added to increase torque capacity, then torque transfer capacity improves, but device complexity and cost increase
Solution Approach 1:
The patent utilizes the radial dimension by creating friction surfaces at two different diameters rather than adding more friction members in the axial direction. This approach increases torque capacity by exploiting the moment arm difference between inner and outer radii, achieving higher torque without proportionally increasing the number of friction members or their complexity.
Solution Approach 2:
The clutch design makes the friction members multi-functional by enabling each friction member to contribute to torque transmission at two different radial locations (inner and outer surfaces). This universal utilization of existing friction members increases torque capacity without requiring additional friction members, thereby avoiding increased complexity and cost.
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 enhances torque transfer capacity by increasing the force applied to friction members, improving efficiency and reducing parasitic losses, while maintaining operational simplicity and cost-effectiveness.
Implementation Method 1
fluid received in the fluid chamber results in the at least one friction disc and the at least one friction plate being pressed together between the piston and the backing plate
Implementation Method 2
Upon engagement of the lock-up clutch, interaction between the friction members transfers torque between the clutch housing and the output shaft of the torque converter
Data Source
AI summary
A lock-up clutch assembly for a torque converter includes a clutch housing defining an annular clutch chamber, and an annular piston received in the clutch chamber and extending between the inner diameter and outer diameter of the clutch chamber. The piston defines inner and outer diameters associated respectively with the inner and outer diameters of the clutch chamber. The assembly further includes a backing plate received in the clutch chamber, and at least one annular friction disk and at least one annular friction plate received in the clutch chamber between the piston and the backing plate. The assembly further includes first and second seal members configured to provide respective fluid seals between the inner diameters of the piston and clutch chamber and between the outer diameters of the piston and clutch chamber.