Friction Shift Element with Segmented Lugs for Drag Torque Reduction
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Solution Overview
Problem
Existing friction shift elements in vehicle transmissions are inefficient in reducing drag torques, leading to higher fuel consumption and increased mass and installation space requirements.
Innovation Solution
A friction shift element design featuring alternately arranged first and second friction elements with ring-shaped surfaces, interrupted by radial friction lugs or teeth, allowing coolant and lubricant to flow freely and minimizing contact surfaces, along with optional conical or flattened sections for reduced axial pressure and enhanced strength, and incorporating spring clips for forced distancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If friction elements are designed with continuous friction surfaces, then torque transmission capacity is improved, but drag torques increase and fuel consumption increases
Solution Approach 1:
The continuous friction surface is segmented into multiple discrete friction lugs or friction teeth arranged circumferentially on the friction element. This segmentation reduces the total contact area between friction elements, thereby reducing drag torques and energy loss while maintaining sufficient torque transmission capacity through the distributed friction lugs.
2Power
If friction elements are pressed together with high axial force, then torque transmission is improved, but mass and installation space requirements increase
Solution Approach 1:
The friction elements are segmented with discrete friction lugs rather than continuous surfaces, allowing for reduced axial pressing forces while maintaining effective torque transmission. This reduces the structural mass required to withstand high axial loads.
Solution Approach 2:
The friction contact is shifted from axial pressing to circumferential distribution through multiple friction lugs. This dimensional change allows torque transmission to be achieved with lower axial forces, reducing the mass and size requirements of the friction switching element.
3Power
If friction surfaces have full contact area, then torque transmission is improved, but coolant and lubricant flow is restricted
Solution Approach 1:
The continuous friction surface is segmented into discrete friction lugs with gaps between them. These gaps create flow channels that allow coolant and lubricant to pass through the friction element package, improving thermal management and lubrication while maintaining sufficient friction contact area for torque transmission.
4Stress or pressure
If friction elements are designed without linings, then permissible surface pressure increases, but manufacturing complexity and cost increase
Solution Approach 1:
The friction element is designed with discrete friction lugs that can be formed directly from the base material without requiring separate lining materials. This segmented design allows for simpler manufacturing processes such as stamping or casting, reducing manufacturing complexity and cost while achieving high permissible surface pressures through the concentrated friction contact areas.
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 significantly lower drag torques, reduced fuel consumption, lighter weight, and improved driving dynamics while maintaining effective torque transmission and thermal performance.
Implementation Method 1
at least one first friction element (1, 3) and at least one second friction element (1, 3) can be brought into contact as friction partners with overlapping friction surfaces for torque transmission
Implementation Method 2
at least one spring clip (10, 10A) is provided on each friction surface element (5) in the circumferential direction, which are resilient in the axial direction
Data Source
Figure 1~2
Figure 3~4
Figure 5~9
AI summary
Disclosed is a frictional shifting element for a vehicle transmission, comprising at least one first friction element (1) associated with a first support (2), and at least one second friction element (3), associated with a second support (4), as a friction partner. The frictional surfaces of the two friction elements overlap and can be brought in contact with each other to transmit torque. The first friction element (1) or the second friction element (3) has an approximately annular frictional surface (7), and as a corresponding frictional surface, the other friction element (1, 3) has at least one frictional surface element (5) that projects approximately radially into the overlapping zone.