Fan Rotor Freewheel Sleeve for Reverse Rotation Blocking
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Solution Overview
Problem
Existing fan designs face challenges in preventing passive rotation of the rotor in the opposite direction of the intended rotation, which can lead to poor starting or failure of sensorless electric motors and require either heavy and expensive mechanical brakes or constant load on motor components.
Innovation Solution
A blocking device comprising a bearing tube, a rotor shaft, and an overrunning sleeve, where the freewheel sleeve is connected rotationally fixed to the rotor shaft and blocks rotation in the opposite direction, with a bushing limiting rotation relative to the bearing tube, and optionally includes a spring for axial positioning and a bearing for concentric mounting.
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 rotor shaft assembly through a freewheel sleeve. The freewheel sleeve is mounted on the rotor shaft and provides one-way locking directly at the rotation source, eliminating the need for a separate mechanical brake and reducing overall fan weight.
Solution Approach 2:
The freewheel sleeve is nested on the rotor shaft, creating a compact nested structure where the locking mechanism is contained within the existing rotor assembly. This nested arrangement prevents passive rotation without adding external components, thereby reducing weight and cost.
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 cost increases
Solution Approach 1:
The invention merges the braking function with the rotor shaft assembly by integrating the freewheel sleeve directly onto the rotor shaft. This combination eliminates the need for separate brake components, reducing part count, simplifying manufacturing, and lowering production costs while maintaining reliable prevention of passive rotation.
Solution Approach 2:
The freewheel sleeve serves multiple functions: it allows free rotation in the normal operating direction, blocks rotation in the opposite direction, and integrates with the rotor shaft assembly. This multi-functionality reduces the need for separate components, simplifying manufacturing and reducing costs.
3Reliability
If electrical self-locking by the motor is used to prevent passive rotation, then the rotor rotation is blocked, but there is a constant load on the motor and motor electronics reducing service life
Solution Approach 1:
The invention replaces the electrical self-locking mechanism with a passive mechanical freewheel sleeve that provides one-way locking through its internal ratchet mechanism. This mechanical solution requires no electrical power, imposes no constant load on the motor or electronics, and extends the service life of these components while reliably preventing passive rotation.
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
Effectively prevents rotor rotation in the opposite direction of the intended rotation, enhancing motor starting performance while reducing component wear and maintaining cost-effectiveness.
Implementation Method 1
The bearing can be a radial bearing or a combination of radial and axial bearings and is preferably designed as a ball bearing
Implementation Method 2
a spring, in particular a compression spring, is arranged between the bearing and the bushing. The spring rests directly or indirectly on the bushing and the bearing and pushes them apart in the axial direction
Implementation Method 3
the freewheel sleeve blocks a rotation of the rotor shaft at least with respect to the bearing tube in the direction of rotation of the rotor
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a blocking device (1) of a fan for blocking a direction of rotation of a rotor (70), via which a wheel of the fan can be driven, comprising a bearing tube (10), a rotor shaft (60) and a freewheel sleeve (50), wherein 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 therewith, and wherein 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.