Actuator Assembly with Roller Ramp Unit for Low Friction Clutch Operation
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Solution Overview
Problem
Existing driveline systems for motor vehicles face challenges in efficiently operating clutches with low friction losses and requiring minimal actuating forces, leading to increased construction space and weight.
Innovation Solution
An actuator assembly comprising a drive unit and a ramp unit with rollers and ramps that convert rotational movement into translational movement, providing low-friction axial support and eliminating the need for separate axial bearings, allowing for a compact and simple design with low power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional clutch actuation systems are used, then reliable clutch operation is achieved, but friction losses increase and require larger construction space and weight
Solution Approach 1:
The patent combines the functions of axial support and rotational movement transmission into a single integrated ramp unit structure. The first ring serves both as a structural element providing axial support through the rollers and as a rotating component that transmits torque from the drive unit. This merging eliminates the need for separate axial bearings and reduces the number of parts, thereby reducing construction space and weight while maintaining reliable operation and reducing friction losses.
Solution Approach 2:
The first ring in the ramp unit performs multiple functions simultaneously: it provides axial support for the rollers (bearing function), transmits rotational movement from the drive unit (drive transmission function), and guides the rollers during operation (guiding function). This multi-functionality reduces the overall device complexity and eliminates the need for separate dedicated components for each function, thereby reducing construction space and weight.
2Reliability
If separate axial bearings are used to support the first ring, then axial support is provided, but device complexity and construction space increase
Solution Approach 1:
The axial support function is merged into the ramp unit structure itself. The first ring, through its interaction with the rollers on the ramps, provides the necessary axial support without requiring separate axial bearings. This integration reduces the number of components and simplifies the overall device structure while maintaining reliable axial support during clutch operation.
Solution Approach 2:
The first ring is designed as a multi-functional component that simultaneously provides axial support (through roller interaction), transmits rotational movement (from the drive unit), and guides the rollers. By making the first ring universal in its functions, the patent eliminates the need for separate dedicated axial bearings, thereby reducing device complexity and the number of components.
3Power
If high friction forces are present in the ramp assembly, then torque transmission is maintained, but the drive unit requires higher nominal power and increased construction space
Solution Approach 1:
The patent employs curved ramp surfaces with optimized profiles that guide the rollers smoothly during axial movement. The curved geometry of the ramps reduces sliding friction by promoting rolling contact, thereby reducing the friction forces that the drive unit must overcome. This allows for lower nominal power in the drive unit while maintaining effective torque transmission through the clutch mechanism.
Solution Approach 2:
The patent optimizes the geometric parameters of the ramp surfaces, including the angle and profile of the ramps, to minimize friction forces during operation. By carefully selecting and adjusting these parameters, the design achieves a balance between maintaining sufficient torque transmission capability and reducing the friction losses that would otherwise require a more powerful (and larger) drive unit.
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 actuator assembly achieves low friction losses and reduced power requirements, enabling a smaller and lighter driveline system with efficient clutch operation and reduced construction space, while maintaining effective torque transmission and braking capabilities.
Implementation Method 1
there are arranged two rollers axially supported against each other and in rolling contact with each other
Implementation Method 2
the rollers act as axial rolling contact bearings, so that, because of the rolling contact, there occur only particularly low friction forces
Data Source
AI summary
An actuator assembly for being operated in the driveline of a motor vehicle comprises a drive unit for generating an operating force and a ramp unit drivable by the drive unit. The ramp unit comprises an abutment element, a first ring and a second ring. The first ring is drivable by the drive unit so as to rotate around a rotational axis (A) and a plurality of circumferentially distributed axial through-openings. In each of the axial through-openings two rollers are arranged of which respectively a first roller is axially supported against the abutment element and a second roller is axially supported against the second ring The second ring is configured to be held in a stationary component in a rotationally fixed and axially movable way and comprises a plurality of circumferentially distributed ramps which each cooperate with an associated roller. The ramps are configured such that rotatingly driving the rotatingly drivable first ring by the drive unit generates an axial movement of the second ring relative to the first ring. A clutch assembly can have such an actuator assembly.