Torque Clutch With Roller Disks to Prevent Glazing
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Solution Overview
Problem
Existing torque transmission devices for electromechanical actuators in aircraft flight control surfaces face issues with maintaining high torque transmission efficiency while preventing excessive torque transmission, and they deteriorate over time due to glazing effects that reduce friction coefficients.
Innovation Solution
A torque transmission device comprising multiple friction disks and roller disks with a solenoid and resilient member, allowing selective torque transmission through disk-to-disk and disk-to-roller interfaces, which mitigates glazing effects by using a Belleville spring and needle thrust bearings to manage axial load paths and prevent excessive torque when the solenoid is not energized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solenoid-based clutch mechanism is used to selectively transmit torque, then torque transmission can be controlled between input and output shafts, but the device transmits too high torque when intended not to transmit torque and deteriorates over time due to glazing effects
Solution Approach 1:
The device segments the torque transmission path into multiple interfaces: disk-to-disk interfaces for high torque transmission and disk-to-roller interfaces for low torque transmission. This segmentation allows the system to switch between different transmission modes by changing which interfaces are actively loaded, preventing glazing at the primary torque transmission interface and maintaining consistent performance over time.
Solution Approach 2:
Roller disks are introduced as intermediary elements between the friction disks. These rollers act as mediators that can bear axial loads while minimizing friction and preventing glazing effects. The needle thrust bearings within the roller disks further mediate the load transfer, enabling the system to maintain reliable torque transmission control without the deterioration issues of direct disk-to-disk contact.
2Force
If axial load paths are loaded to transmit high torque, then high torque transmission is achieved, but the device becomes compact while transmitting high torque with a small solenoid
Solution Approach 1:
The device dynamically switches between different axial load paths based on the solenoid's energized state. When the solenoid is energized, axial load is applied through the first resilient member to engage the disk-to-disk interfaces for high torque transmission. When de-energized, the load path shifts to allow free rotation with minimal torque transmission. This dynamic load path switching enables high torque capability in a compact design.
Solution Approach 2:
The system changes the axial load parameter applied to different interfaces based on operational requirements. The first resilient member controls the axial load on disk-to-disk interfaces to enable high torque transmission when needed, while the second resilient member manages axial load on disk-to-roller interfaces for low torque modes. This parameter control allows compact sizing while maintaining high torque capability when required.
3Force
If disk-to-disk interfaces are used for torque transmission, then high torque transmission is achieved, but glazing effects reduce friction coefficients over time
Solution Approach 1:
The harmful glazing effect is extracted from the primary torque transmission path by introducing roller disks with needle thrust bearings. These rollers take out the direct sliding contact between friction disks, eliminating the glazing mechanism while preserving the high torque transmission capability through the disk-to-roller-disk interfaces. The friction surfaces are separated by rolling elements that do not exhibit glazing.
Solution Approach 2:
The sliding friction mechanism between disks is substituted with a rolling contact mechanism using roller disks and needle thrust bearings. This mechanical substitution replaces the glazing-prone sliding interface with a rolling interface that maintains stable friction characteristics over time, while still enabling high torque transmission through the interdigitated disk arrangement.
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 device maintains high torque transmission efficiency without glazing effects, ensuring consistent performance over time by controlling torque transmission through distinct axial load paths, thus addressing the limitations of existing devices.
Implementation Method 1
The first resilient member is configured to provide an axial load through the first and second plurality of friction disks and roller disks
Implementation Method 2
The solenoid is configured to overcome the force from the first resilient member when energised
Implementation Method 3
using a Belleville spring and needle thrust bearings to manage axial load paths
Implementation Method 4
using a Belleville spring and needle thrust bearings to manage axial load paths and prevent excessive torque
Data Source
Figure 1
Figure 2A~2C
Figure 3~4A
AI summary
There is provided herein a device (30A) for selectively transmitting torque between an input shaft (32A) and an output shaft (34A), including: a first plurality of friction disks (36A) configured to rotate with the input shaft (32A); a second plurality of friction disks (38A) configured to rotate with the output shaft (34A) and interdigitated with the first plurality of friction disks (36A); a plurality of roller disks (40A) wherein each of the plurality of roller disks (40A) includes a first disk-to-roller interface (44A) with one of the first plurality of friction disks (36A) and a second disk-to-roller interface (44A) with one of the second plurality of friction disks (38A); a first resilient member (50A) configured to provide a force (FSPR) through the first and second plurality of friction disks (38A, 36A) and roller disks (40A); a solenoid (56A) configured to overcome the force (FSPR) from the resilient member (50A) when energised. the device (30A) may be selectively placed in one of a first mode and a second mode. In the first mode only a low torque is transmittible through the device and in the second mode a higher torque is transmittable through the device (30A). An assembly, aircraft and methods are also provided.