Slip Clutch Stacked Washers Oil Groove Torque Limiting
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Solution Overview
Problem
Conventional slip clutches are heavy, prone to failure due to ball bearing fracture, and do not meet ANSI standards for independent activation in industrial applications, particularly in hand-held power drills used for torque transmission.
Innovation Solution
A lightweight slip clutch assembly using stacked washers with oil grooves and a compression spring, which requires two independent actions for activation, ensuring consistent torque limitation and preventing damage from overloading by immersing the washers in an oil reservoir for consistent performance across environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heavier materials are used in clutch construction, then the clutch can provide robust overload protection, but the total weight of the device increases, which is problematic for hand-held power tools
Solution Approach 1:
The clutch is segmented into multiple thin washer components rather than a single heavy solid structure. This segmentation allows the use of lightweight materials while distributing the load and torque limitation function across multiple components, achieving robustness without excessive weight.
Solution Approach 2:
The patent employs composite construction with washers made from materials optimized for both strength and weight, combined with oil grooves that provide lubrication. This composite approach to material selection and structural design achieves the necessary mechanical strength while minimizing the overall weight for hand-held tool applications.
2Ease of manufacture
If a simple clutch design is used, then manufacturing is easier and weight is reduced, but the clutch may not provide consistent activation across environmental conditions
Solution Approach 1:
The oil grooves in the washers introduce an intermediary lubricating film between the sliding surfaces. This oil intermediary ensures consistent friction characteristics and torque activation across varying environmental conditions, maintaining precision despite the simplicity of the overall design.
Solution Approach 2:
The patent utilizes changes in oil viscosity and film thickness as intermediate parameters to maintain consistent friction and torque characteristics. By controlling the lubrication parameters through the oil grooves, the system achieves consistent activation torque despite environmental variations, while keeping the mechanical structure simple.
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 provides a robust, lightweight, and consistent overload protection that meets ANSI standards, ensuring accurate torque limitation and extended durability, allowing safe and efficient use of hand-held power drills in industrial applications.
Implementation Method 1
Each of the washers includes an oil groove or a plurality of oil grooves on one surface thereof, where the oil grooves maintain a consistent film of oil on the washer surfaces
Implementation Method 2
The slip clutch may additionally include a compression spring disposed within the housing that acts to maintain a minimum compression force on the stacked washers
Implementation Method 3
The stacked washers slip relative to one another such that the shaft rotates relative to the housing upon an application of a predetermined torque
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
A slip clutch (10) acts between a shaft (12) and a housing (14). The slip clutch (10) includes an oil reservoir (34) within the housing (14) and one or more slipping surfaces disposed in the oil reservoir (34) that are keyed to the shaft and possibly alternately to the housing (14). The slipping surfaces may include stacked plates or washers (20). Each of the washers (20) includes an oil groove (40) or other structure on one surface thereof that maintains a consistent film of oil on the washer surfaces. The stacked washers (20) slip relative to one another such that the shaft (12) rotates relative to the housing (14) upon an application of torque that exceeds a predetermined torque.