Flex Shaft Lock Sleeve Assembly for Rotary Knife
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Solution Overview
Problem
Flexible shaft drive transmissions in power operated rotary knives experience significant lubricant leakage due to gravity, leading to increased friction, heat, and reduced operational life, and the drive transmitting shaft is not securely locked within the casing, causing inconvenience and contamination.
Innovation Solution
A method of assembling a shaft drive transmission with a lock sleeve and a drive shaft assembly that includes a flexible elongated flex shaft, where the lock sleeve is slid onto the outer casing and advanced to secure the motor end of the flex shaft, preventing leakage and ensuring proper alignment and secure positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the drive transmitting shaft rotates within the outer casing without a lock sleeve, then the shaft can rotate freely to transmit power, but lubricant leaks out between the shaft and casing due to gravity
Solution Approach 1:
The lock sleeve is divided into two functional portions: a first portion that contacts the drive shaft to prevent axial movement, and a second portion that contacts the outer casing to seal the lubricant. This segmentation allows the single lock sleeve component to simultaneously enable free rotation while preventing lubricant leakage.
Solution Approach 2:
The lock sleeve acts as an intermediary component between the drive shaft and the outer casing. It provides a sealing interface that prevents lubricant from migrating from the space between the shaft and casing, while still allowing the shaft to rotate freely within the sealed environment.
2Ease of manufacture
If the drive transmitting shaft is not secured within the outer casing, then assembly is simple, but the shaft is not securely locked causing inconvenience and contamination
Solution Approach 1:
The lock sleeve is integrated as a single component with two distinct functional zones: one zone engages the drive shaft to prevent axial displacement, while the other zone contacts the outer casing to provide sealing. This integrated design maintains assembly simplicity while achieving secure shaft positioning.
Solution Approach 2:
The lock sleeve is nested within the outer casing and simultaneously engages the drive shaft. This nested configuration allows the lock sleeve to be installed in a straightforward manner while providing secure mechanical engagement that prevents shaft displacement and ensures reliable operation.
3Speed
If lubricant is allowed to migrate toward the handle assembly coupling due to gravity, then the shaft can rotate freely, but friction and heat increase reducing operational life
Solution Approach 1:
The lock sleeve serves as a mediator that creates a sealed environment around the drive shaft. This sealing action prevents lubricant from migrating toward the handle assembly coupling where it would cause increased friction and heat, thereby protecting the operational life of the drive transmission while maintaining smooth shaft rotation.
Solution Approach 2:
The lock sleeve extracts or removes the harmful effect of gravity-driven lubricant migration by creating a sealed barrier. This prevents the lubricant from reaching areas where it would cause excessive friction and heat generation, thus preserving the operational life of the transmission components.
Data Source
Figure 1
Figure 2
Figure 2A
AI summary
A method of assembling a flexible shaft drive transmission (4701) coupled between a drive motor and a power operated tool including the steps of: providing a drive transmitting shaft assembly (4800) including a flexible, elongated flex shaft (4702); providing an outer casing assembly (4702) including an outer casing (4704) defining a longitudinally extending throughbore and having a motor end (4710) and a tool end (4780); sliding a lock sleeve (4750) onto the motor end of the outer casing to a recessed position with respect to the motor end of the casing; inserting the motor end of the flex shaft through the tool end of the outer casing; affixing a driven fitting (4814) to the motor end of the flex shaft; advancing the lock sleeve to overlie the motor end of casing; and affixing a casing portion (4762) of the lock sleeve to the outer casing.