Friction Lamella Groove Pattern for Uniform Cooling
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Solution Overview
Problem
Existing non-positive shifting elements, such as multi-plate clutches and brakes, experience uneven cooling distribution when cooled with oil, with the radially outer area being cooled more effectively than the radially inner area due to centrifugal forces, leading to inefficient heat dissipation.
Innovation Solution
The groove pattern on the lamella is modified by aligning the second grooves at an angle between 35 and 75 degrees relative to the radial direction, allowing cooling liquid to flow into both the circumferential first groove and the second grooves, improving cooling of the radially inner area, and maintaining this effect regardless of the direction of rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling oil is supplied from the radial outside to the third grooves, then the radially outer area of the friction surface is cooled well, but the radially inner area is insufficiently cooled due to centrifugal forces flinging oil out through the third grooves
Solution Approach 1:
The groove pattern is designed with different orientations in different radial zones. The third grooves are oriented radially to capture oil from the outer edge, while the second grooves are oriented obliquely (35-75 degrees to radial direction) to channel oil toward the inner deflection points. This local variation in groove orientation ensures that each radial zone has grooves optimally positioned to receive and channel cooling oil, addressing the uneven cooling distribution.
Solution Approach 2:
The second grooves are oriented obliquely rather than radially, introducing an angular component to the oil flow path. This changes the flow dynamics from purely radial outward-to-inward movement to a combined radial and circumferential flow pattern, allowing oil to penetrate more effectively against centrifugal forces and reach the inner friction surface areas.
2Ease of manufacture
If the second grooves run radially as in prior art, then the groove pattern is simple, but the cooling effect in the radially inner area remains insufficient
Solution Approach 1:
Rather than making all grooves oblique throughout, the invention applies the oblique orientation specifically to the second grooves that terminate at the inner deflection points, while keeping the third grooves essentially radial. This localized application of complexity only where needed (in the inner cooling zone) maintains manufacturing simplicity elsewhere while achieving the required cooling improvement.
3Temperature
If the second grooves are oriented obliquely at 35-75 degrees to the radial direction, then cooling of the radially inner area is improved, but the groove pattern becomes more complex
Solution Approach 1:
The oblique groove orientation is applied selectively only to the second grooves in the inner region where cooling improvement is needed, rather than throughout the entire friction surface. The third grooves remain essentially radial, maintaining simplicity in the outer region. This localized approach minimizes the increase in overall device complexity.
Solution Approach 2:
The invention specifies a particular angular range (35-75 degrees, preferably 45-65 degrees) for the oblique orientation of the second grooves. This parameter optimization balances the competing requirements: angles within this range provide sufficient obliquity to overcome centrifugal forces and improve inner area cooling, while not being so extreme as to excessively complicate the groove pattern or reduce manufacturing ease.
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 enhances the cooling effect of the radially inner friction surface, reducing flow loss and ensuring even cooling across the radius, making the non-positive shifting element more suitable for high-energy starting processes in motor vehicle transmissions.
Implementation Method 1
A significant portion of the oil is flung out again by centrifugal forces via the third grooves without penetrating the second grooves
Data Source
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AI summary
The invention relates to a lamella (1) for a frictional shift element, comprising an annular friction surface having an inner edge (21) and an outer edge (22) and containing a peripheral first groove (31), a plurality of second grooves (32) and a plurality of third grooves (33), the first groove (31) extending in a zig-zag or wave-like manner between radially inner and radially outer deflection points (41, 42), the second grooves (32) extending from the inner edge (21) to the radially inner deflection points (41), and the third grooves (33) extending from the outer edge (22) into the peripheral first groove (31) and leading into the peripheral first groove (31) at bifurcation points (43), the third grooves (33) being oriented from the bifurcation points (43) essentially in the radial direction towards the outer edge (22), the orientation of at least the section of the second grooves (32) which leads into the radially inner deflection points (41), and a line (45) between a rotational central point (44) of the lamella (1) and the deflection point (41) associated with the respective second groove (32), enclosing an angle (46a) of between between 35 and 75 degrees.