Wet Friction Material Segmented Recesses Drag Torque
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Solution Overview
Problem
Conventional wet friction materials face challenges in reducing drag torque generated by contact resistance and shearing torque between ATF and the inner and outer peripheral end faces of segment pieces, limiting their effectiveness in achieving low drag torque while maintaining desired torque transmission.
Innovation Solution
The wet friction material features a plurality of segment pieces bonded annularly on a core plate with inter-segment grooves, where each segment piece has inner and outer peripheral recesses, with the recessed amount ranging from 1/10 to 1/3 of the radial width, reducing contact resistance and shearing torque by allowing ATF to overflow and form an oil film, thereby minimizing drag torque while ensuring torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If lubricating oil grooves are formed with large width parts by cutting in the inner peripheral opening portion and/or middle part of segment pieces, then drag torque is reduced by allowing ATF to overflow, but the structural complexity increases and manufacturing precision requirements increase
Solution Approach 1:
The friction material is divided into multiple segment pieces arranged radially, with lubricating oil grooves formed between adjacent segments. This segmentation allows ATF to flow through the grooves and overflow at controlled points, reducing drag torque while maintaining a simpler overall structure compared to forming complex grooves within each segment piece.
Solution Approach 2:
The lubricating oil grooves act as intermediary channels between the inner and outer peripheral sides of the friction material. These grooves facilitate ATF flow and overflow without requiring complex cut-in parts within the segment pieces themselves, thereby reducing manufacturing complexity while still achieving drag torque reduction.
2Loss of energy
If cut-in parts are formed on the inner peripheral end portion and/or middle part of segment pieces to create non-linear end surfaces, then drag torque is reduced by blocking and overflowing ATF, but manufacturing precision and production time increase
Solution Approach 1:
Instead of forming complex cut-in parts on each segment piece, the invention uses radial segmentation with grooves formed between segments. This approach achieves ATF control and overflow with simpler manufacturing processes, reducing the precision requirements compared to forming non-linear end surfaces on each segment.
Solution Approach 2:
The lubricating oil grooves are formed by the facing lateral end surfaces of adjacent segment pieces, merging the function of groove formation into the segment assembly process itself. This eliminates the need for separate cut-in operations on each segment, reducing manufacturing precision requirements and production time.
3Productivity
If segment pieces are made large to occupy nearly full width of the ring shape, then the number of segment pieces is reduced and production time is shortened, but drag torque reduction effectiveness decreases
Solution Approach 1:
The friction material uses multiple radially arranged segment pieces with lubricating oil grooves between them. This segmentation strategy allows for effective drag torque reduction through controlled ATF overflow while maintaining a manageable number of segments, balancing production efficiency with performance effectiveness.
Solution Approach 2:
The lubricating oil grooves utilize hydraulic principles to channel and overflow ATF, creating effective drag torque reduction. This hydraulic approach allows smaller segment pieces to achieve the same drag reduction effect as larger segments would need without grooves, thereby improving production efficiency without sacrificing performance.
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 configuration effectively reduces drag torque by minimizing contact resistance and shearing torque, while maintaining desired torque transmission, and prevents peeling-off issues by regulating the inner peripheral end portion's width within 0.3 to 2 mm, ensuring durability and efficient ATF flow management.
Implementation Method 1
ATF flowing into the inner peripheral recess overflows to a top surface of the segment piece to form an oil film
Implementation Method 2
The inner peripheral recesses reduce a contact resistance generated between an inner peripheral part of the segment piece and ATF flowing along the inner periphery of the segment piece, while restraining a resultant shearing torque
Data Source
AI summary
In a wet friction material, a plurality of segment pieces is disposed at both sides of inter-segment grooves. The segment pieces are composed of first segment pieces and second segment pieces. The first segment piece has at least two inner peripheral recesses formed on an inner periphery thereof and at least two outer peripheral recesses formed on an outer periphery thereof. The outer periphery of the first segment piece has a short dimension. The second segment piece has at least two inner peripheral recesses formed on an inner periphery thereof and at least two outer peripheral recesses formed on an outer periphery thereof. The outer periphery of the second segment piece has a long dimension.