Blower Wheel Nut Retensioning for Easy Removal and Secure Fastening
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Solution Overview
Problem
Blower wheels in handheld blower apparatuses are difficult to remove due to secure fastening mechanisms, requiring high tightening moments and safety factors, which complicates installation and removal processes.
Innovation Solution
A blower wheel fastening system using a nut with frictional contact surfaces that automatically retension the blower wheel against the shaft, allowing for easy removal without high tightening moments, utilizing a thread moment of friction and conical friction contact surfaces to transmit frictional forces, reducing the overall release moment and enabling simple disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a secure fastening mechanism with high tightening moment is used to prevent slippage, then the reliability of the connection is improved, but the ease of removal deteriorates
Solution Approach 1:
The fastening system transitions from a static high-tightening state to a dynamic self-retensioning state. During operation, the nut automatically retensions the blower wheel against the shaft through frictional forces generated by relative movement, maintaining secure connection without requiring permanently high tightening moments. This dynamic adaptation resolves the contradiction by providing both reliability during operation and ease of removal when operation ceases.
Solution Approach 2:
The nut is designed to automatically retension the blower wheel during operation without operator intervention. The frictional contact surfaces and conical geometry enable the system to self-adjust and maintain optimal connection security dynamically, eliminating the need for operator-applied safety factors and high tightening moments while ensuring reliable operation.
2Reliability
If a high tightening moment is applied during installation, then the reliability of the connection is improved, but the device complexity increases due to safety factors
Solution Approach 1:
The fastening system automatically retensions itself during operation through the interaction of frictional contact surfaces and conical geometry. The nut moves along the shaft via frictional force and automatically retensions the blower wheel, eliminating the need for operator-applied safety factors and complex high-tightening mechanisms.
Solution Approach 2:
The system changes the tightening moment parameter dynamically during operation. The minimum tightening moment during installation is reduced to 10%-100% of operating torque, and the conical friction contact surface generates additional retensioning force during operation, optimizing the connection security parameter without requiring permanently high initial tightening.
3Reliability
If frictional contact surfaces are designed to prevent slippage, then the reliability is improved, but the tightening moment required increases
Solution Approach 1:
The frictional force required to prevent slippage is generated dynamically during operation rather than requiring high initial tightening. The conical friction contact surface between the nut and blower wheel, combined with the first friction contact surface between the nut and shaft, generates retensioning force through relative movement, maintaining anti-slippage capability with reduced tightening moment.
Solution Approach 2:
The solution introduces a conical geometry dimension to the friction contact surfaces. The conical friction contact surface running at an angle to the rotational axis creates additional frictional retensioning force through the wedge effect, enabling reliable anti-slippage performance without proportionally increasing the axial tightening moment.
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 system allows for automatic retensioning of the blower wheel during operation, reducing the need for high tightening moments and safety factors, facilitating easy installation and removal, while maintaining secure fastening and preventing slippage, thus enhancing operational efficiency and safety.
Implementation Method 1
the nut and the blower wheel being in contact via a first friction contact surface wherein a first moment of friction (M1) acting about the rotational axis is transmittable between the nut and the blower wheel via the first friction contact surface
Implementation Method 2
the blower wheel and the shaft being in contact via a second friction contact surface... the blower wheel moves the nut along therewith via the first moment of friction (M1) acting at the first friction contact surface so that the nut retensions the blower wheel against the shaft via the second friction contact surface
Implementation Method 3
the nut and the shaft being in contact via a thread section wherein an acting thread moment of friction (MA) acting about the rotational axis is transmittable between the nut and the shaft via the thread section
Data Source
AI summary
A handheld work apparatus has a blower wheel. The blower wheel is held via a nut on the shaft in a manner locked against rotation by frictional force. A thread moment of friction is transmittable between the nut and the shaft via a thread section. A first moment of friction is transmittable between the nut and the blower wheel via a first friction contact surface. The first friction contact surface is configured such that, at a minimum tightening torque of the nut, the first moment of friction is greater than the thread moment of friction. As a result, during the operation of the work apparatus when there is a relative movement between the blower wheel and the shaft, the blower wheel moves the nut along therewith. The nut retensions the blower wheel against the shaft. The second friction contact surface runs conically with respect to the rotational axis.