Segmented Wet Friction Member Layout for Low Drag Torque
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Solution Overview
Problem
Conventional wet friction members in automatic transmissions experience high drag torque, leading to increased fuel consumption, despite existing techniques that do not effectively reduce this issue, especially in low rotation regions.
Innovation Solution
A wet friction member design featuring a core plate with segment pieces arranged in a ring shape via oil grooves, including notched rectangular segments and specific oil groove configurations that facilitate lubricating oil flow and discharge, reducing contact with separator plates and enhancing lubricating oil distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional wet friction members are used with standard oil groove designs, then the structure is simple and easy to manufacture, but drag torque is high especially in low rotation regions
Solution Approach 1:
The wet friction member is divided into multiple segment pieces arranged in a ring shape, with oil grooves formed between adjacent segments. This segmentation allows lubricating oil to be distributed to multiple locations simultaneously, improving lubrication effectiveness and reducing drag torque without requiring complex internal oil groove structures within each segment
Solution Approach 2:
The invention transitions from traditional internal oil grooves within single friction members to inter-segment oil grooves in the radial dimension between adjacent segment pieces. This dimensional change enables lubricating oil to reach friction surfaces more effectively, particularly in low rotation regions, by utilizing the gap space between segments rather than relying on internal groove pathways
2Reliability
If lubricating oil is supplied to reduce friction and absorb heat, then friction is reduced and heat is absorbed, but drag torque is generated during idle rotation
Solution Approach 1:
Different regions of the wet friction member are given different properties: segment pieces provide friction surfaces for torque transmission, while the gaps between segments form oil grooves that supply lubricating oil to specific locations. This local differentiation ensures that lubrication is provided where needed to reduce friction and absorb heat, while the segmented structure allows excess oil to be discharged, reducing drag torque during idle rotation
3Loss of energy
If oil grooves are designed to discharge excessive lubricating oil, then drag torque is reduced, but lubrication effectiveness may be compromised
Solution Approach 1:
The ring-shaped arrangement of segment pieces with inter-segment oil grooves creates a continuous lubrication pathway around the entire circumference of the wet friction member. Lubricating oil supplied at any location continuously flows through the gap between segments, ensuring uninterrupted lubrication of friction surfaces. This continuous action maintains lubrication effectiveness while allowing excessive oil to be discharged, achieving both reduced drag torque and reliable lubrication
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 design achieves a significant reduction in drag torque across various rotation speeds, particularly in low rotation regions, and maintains effective lubrication, thereby improving fuel efficiency.
Implementation Method 1
Lubricating oil is supplied into the clutch, for example, to reduce the friction of the wet friction members in the pressure contact/separation and to absorb the frictional heat caused by friction
Implementation Method 2
a wide part having a wide groove width is formed in an inner peripheral-side opening part by providing a cut part in a segment piece... lubricating oil is blocked at a point where the groove width changes, with the result that a part of the oil flows out onto a surface of the segment piece
Data Source
AI summary
A wet friction member includes a core plate formed in a flat ring shape; and a friction part arranged on a main surface of the core plate. The friction part is formed in such a manner that four kinds of segment pieces, which are a first piece, a second piece, a third piece, and a fourth piece, are repeatedly arranged in this arrangement order in a ring shape via oil grooves.