Oblique Sinusoidal Friction Plates for Wet Clutch Stability
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Solution Overview
Problem
Wet friction clutches experience increased spin losses and instability at high differential speeds due to gyroscopic tumbling of rotating friction plates, with existing sinusoidal core plates being ineffective in reducing these issues at high speeds.
Innovation Solution
Friction clutch packs with friction plates featuring multiple obliquely oriented or angularly offset sinusoidal waves, along with male splines around the periphery engaging complementary splines on a cylindrical housing, and flat reaction plates with female splines, which provide improved stability and reduced spin losses at high differential speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If shallow circumferential sinusoidal profile core plates are used, then spin losses are reduced at low relative speeds, but high differential speed instabilities and spin losses increase due to gyroscopic tumbling
Solution Approach 1:
The patent applies asymmetry by using obliquely oriented sinusoidal waves instead of symmetric circumferential waves. The waves are angled at approximately 45 degrees relative to the radial direction, creating an asymmetric profile that prevents gyroscopic tumbling at high speeds while maintaining spin loss reduction at low speeds. This asymmetric geometry fundamentally changes how the friction plate interacts with the clutch pack during rotation.
Solution Approach 2:
The patent changes the geometric parameters of the sinusoidal waves by orienting them obliquely rather than circumferentially. This parameter change in wave orientation transforms the deformation mode of the friction plate, preventing resonance with the first deformation mode that occurs with circumferential waves. The angular orientation parameter is specifically set to approximately 45 degrees to optimize performance across the speed range.
2Loss of energy
If circumferential sinusoidal waves are used, then spin loss reduction is achieved at low speeds, but the geometry conforms to the first deformation mode causing instability at high speeds
Solution Approach 1:
The patent replaces the symmetric circumferential wave pattern with an asymmetric oblique wave pattern. The oblique orientation at approximately 45 degrees to the radial direction creates a geometry that does not conform to the first deformation mode of the friction plate, thereby preventing the resonance and instability that occurs at high differential speeds while maintaining energy efficiency.
3Stability of the object's composition
If high differential speed stability is improved through oblique sinusoidal waves, then spin losses are reduced, but device complexity increases due to formed core plate geometry
Solution Approach 1:
The patent uses curved sinusoidal wave patterns oriented obliquely on the friction plate surface. This curvature approach creates a formed core plate geometry that is more complex than a flat plate but maintains manufacturability through standard forming processes. The curved oblique waves provide the necessary structural characteristics to prevent gyroscopic tumbling while remaining practical for production.
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 configuration enhances high differential speed stability and reduces spin losses, offering improved performance in wet friction clutch applications.
Implementation Method 1
dramatically increased spin losses have been observed when the differential speed increases beyond a certain magnitude. This non-linear spin loss increase has been attributed to instabilities of the rotating friction plates which result from gyroscopic tumbling of the plates.
Implementation Method 2
it is believed that this approach is unsatisfactory at high relative speeds because the sinusoidal geometry essentially conforms to the first deformation mode of the plates
Data Source
AI summary
A friction clutch pack exhibiting improved high speed stability includes a first plurality of friction plates or discs preferably having friction material on both faces interleaved with a second plurality of thicker reaction plates or discs. The friction plates comprise a formed core plate having multiple obliquely oriented or angularly offset sinusoidal waves. Male splines around the periphery of each friction plate engage complementary splines on a cylindrical housing. The reaction plates are flat and thicker than the friction plates and include female splines around an inner opening which engage complementary splines on a shaft or quill.