Friction Plate with Dual Coefficients for Clutch Torque Adaptation
Solution Overview
Problem
Modern automotive automatic transmissions with a Lepelltier layout require a single clutch to perform under varying conditions, necessitating smooth engagement with low torque capacity in one gear and high holding torque in another, which existing clutch assemblies fail to achieve effectively.
Innovation Solution
A clutch assembly with axially movable pressure plates and friction plates having multiple coefficients of friction, where the friction plates have distinct radially inward and outward friction facings to provide smooth engagement and enhanced holding torque, utilizing a piston to actuate the friction pack and adjust frictional engagement based on operational needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single clutch is used in Lepelltier layout transmission, then device complexity is reduced, but the clutch cannot simultaneously provide smooth engagement with low torque capacity and high holding torque capacity
Solution Approach 1:
The friction plate is divided into two distinct friction facings with different coefficients of friction: a first friction facing with lower coefficient for smooth engagement, and a second friction facing with higher coefficient for high torque holding. This local differentiation allows a single clutch assembly to provide different friction characteristics in different operational modes.
Solution Approach 2:
The clutch assembly uses axially movable pressure plates that can shift position to selectively engage different friction facings. The movable pressure plates dynamically adjust which friction facing is active based on operational requirements, enabling the clutch to transition between smooth engagement mode and high torque holding mode.
2Ease of manufacture
If friction plate has uniform coefficient of friction, then manufacturing is simplified, but the clutch cannot provide both smooth engagement and high holding torque
Solution Approach 1:
The friction plate incorporates two friction facings with different coefficients of friction applied to different radial regions. The first friction facing has lower coefficient for smooth engagement, while the second has higher coefficient for torque holding. This local quality differentiation resolves the contradiction by providing both smooth shifting and high holding torque capabilities.
Solution Approach 2:
The friction plate uses composite friction materials with different friction coefficients on different facings. This composite approach allows the single friction plate to exhibit multiple friction characteristics, enabling both smooth engagement and high torque capacity without requiring multiple separate friction plates.
3Force
If friction plate has higher coefficient of friction, then holding torque capacity increases, but engagement smoothness deteriorates
Solution Approach 1:
The friction plate uses a second friction facing with higher coefficient of friction located in the radially outward region to provide high holding torque capacity. Simultaneously, a first friction facing with lower coefficient is positioned to enable smooth engagement. The axial movement of pressure plates selectively activates the appropriate friction facing based on whether high torque or smooth engagement is required.
Solution Approach 2:
The clutch assembly employs axially movable pressure plates that dynamically select which friction facing is engaged. During smooth engagement operations, the pressure plates position to engage the first friction facing with lower coefficient. During high torque holding operations, the pressure plates shift to engage the second friction facing with higher coefficient, thus dynamically optimizing performance for each operational condition.
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 solution enables smooth gear shifting with low torque requirements and high holding torque capabilities, effectively addressing the dual operational demands of the clutch assembly by varying the frictional engagement through differential coefficients and compressibility of the friction facings.
Implementation Method 1
friction plates having multiple coefficients of friction, where the friction plates have distinct radially inward and outward friction facings to provide smooth engagement and enhanced holding torque
Data Source
AI summary
A friction plate is provided including ,a core plate, a core plate first friction facing having a first radius and a first height; and a core plate second friction facing having a second radius differing from the first radius and a second height differing from the first height and having a coefficient of friction differing from a coefficient of friction of the first friction facing, wherein both of the facings are formed from an integral base fiber type friction facing material and wherein the difference in coefficients of friction is due to a percentage of a friction modifying saturant in the facings and wherein there is a groove separating the facings.