Fan Freewheel Sleeve for Reverse Rotor Blocking
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Solution Overview
Problem
Existing fan technologies face challenges in preventing passive rotation of the rotor in the opposite direction of the predetermined rotation, which can lead to difficulties in starting sensorless electric motors and result in mechanical or electrical self-locking solutions that increase costs and reduce component lifespan.
Innovation Solution
A fan blocking device comprising a bearing tube, a rotor shaft, and a freewheel sleeve, where the freewheel sleeve is connected to the rotor shaft and accommodated in the bearing tube for conjoint rotation, blocking rotation in the opposite direction to the predetermined rotation, and optionally includes a bushing and spring mechanism for additional support and positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical brake is used to prevent passive rotation of the rotor, then the rotor rotation in the opposite direction is blocked, but the fan becomes heavy and expensive
Solution Approach 1:
The invention extracts the braking function from a separate mechanical brake component and integrates it into the existing bearing tube structure through a freewheel mechanism. The freewheel sleeve with its one-way locking capability provides the necessary braking action without requiring an additional heavy brake assembly, thus preventing passive rotor rotation while avoiding increased fan weight
Solution Approach 2:
The freewheel sleeve acts as an intermediary element between the rotor shaft and the bearing tube. It mediates the rotational motion by allowing free rotation in the driving direction while automatically locking in the reverse direction, providing the braking function through this intermediate component rather than through a heavy mechanical brake
2Reliability
If a mechanical brake is used to prevent passive rotation of the rotor, then the rotor rotation in the opposite direction is blocked, but the fan becomes expensive
Solution Approach 1:
The invention merges the braking function with the existing bearing tube and rotor shaft assembly by incorporating a freewheel sleeve into the structure. This integration eliminates the need for separate brake components and their associated mounting hardware, simplifying the overall construction and reducing manufacturing costs while effectively preventing passive rotor rotation
Solution Approach 2:
The bearing tube structure is given multiple functions: it serves as both the support structure for the rotor shaft and as the housing for the freewheel braking mechanism. This multi-functionality reduces the total number of components needed and simplifies manufacturing, making the solution more cost-effective compared to adding a dedicated mechanical brake
3Reliability
If electrical self-locking by the motor is used to prevent passive rotation, then the rotor rotation in the opposite direction is blocked, but a permanent load acts on the motor and motor electronics reducing their service life
Solution Approach 1:
The invention replaces the electrical self-locking mechanism with a purely mechanical freewheel sleeve that provides passive one-way locking. This mechanical solution requires no electrical power or electronic control, eliminating the permanent load on motor and electronics while effectively preventing reverse rotation, thus extending the service life of these components
Solution Approach 2:
The freewheel sleeve provides automatic passive locking through its inherent mechanical design without requiring external power or control systems. The mechanism self-activates based on the direction of rotation, locking automatically when the rotor attempts to rotate in the reverse direction, thereby protecting the motor and electronics from permanent load without requiring their active involvement
Data Source
AI summary
A blocking device (1) for a fan that blocks a direction of rotation of a rotor (70), via which a wheel of the fan can be driven. The blocking device has a bearing tube (10), a rotor shaft (60) and a freewheel sleeve (50). The freewheel sleeve (50) is accommodated in the bearing tube (10) and is connected to the rotor shaft (60), which extends through the freewheel sleeve (50), for conjoint rotation. The freewheel sleeve (50) blocks rotation of the rotor shaft (60) at least in relation to the bearing tube (10) in the direction of rotation of the rotor.