Power Tool Rotor Weight Reduction via Resin Bonding
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Solution Overview
Problem
Existing power tool rotors are prone to breaking due to uneven adhesive bonding of permanent magnets, and resin integration methods can fail to adequately lighten rotor cores with holes, leading to insufficient weight reduction.
Innovation Solution
Incorporating an intermediate member with a smaller specific gravity than iron between the rotational shaft and rotor core, and using resin to integrate the rotor components while preventing resin entry into lightening holes, thereby enhancing bonding and reducing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is used to fix permanent magnets onto rotor core, then bonding is achieved, but ununiform bonded surfaces cause centrifugal force concentration and rotor core breaking
Solution Approach 1:
The patent introduces an intermediate member (resin layer) between the permanent magnets and rotor core to create a uniform bonding surface. This intermediary layer distributes centrifugal force evenly across the bonding interface, preventing stress concentration and rotor core breaking while maintaining strong bonding.
Solution Approach 2:
The patent changes the physical state and properties of the bonding material by using resin that is poured under pressure in a liquid state, then cured to form a uniform solid layer. This parameter change from liquid to solid state allows the resin to fill irregularities and create a perfectly uniform bonding surface.
2Strength
If resin is poured under pressure to integrate rotor components, then uniform bonded surfaces and increased rotor strength are achieved, but resin enters lightening holes and weight reduction is insufficient
Solution Approach 1:
The patent performs preliminary action by forming a resin layer on the rotor core surface before mounting permanent magnets. This pre-formed resin layer acts as a barrier that prevents subsequent resin from entering lightening holes during the integration process, while still allowing weight reduction through the lightening holes themselves.
Solution Approach 2:
The patent segments the resin application into two distinct stages: first applying resin to the rotor core surface to create a uniform bonding layer, then separately integrating permanent magnets. This segmentation prevents resin from entering lightening holes while maintaining the benefits of resin-based bonding.
3Weight of moving object
If intermediate member with smaller specific gravity than iron is placed between rotational shaft and rotor core, then rotor weight is reduced, but structural complexity increases
Solution Approach 1:
The intermediate member serves multiple functions simultaneously: it reduces rotor weight by having lower specific gravity than iron, provides electrical insulation between the rotational shaft and rotor core, and acts as a bonding surface for resin. This multi-functionality reduces structural complexity despite adding a component.
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 effectively reduces the weight of the rotor by preventing resin entry into lightening holes and ensuring robust bonding, thus enhancing the structural integrity and efficiency of power tool motors.
Implementation Method 1
an intermediate member having a smaller specific gravity than iron located between the rotational shaft and the rotor core
Implementation Method 2
The resin between the rotational shaft and the rotor core also provides additional insulation
Implementation Method 3
The resin is poured under pressure to achieve uniform bonded surfaces of the permanent magnets with the rotor core and increase the strength of the rotor
Implementation Method 4
When the rotor rotates, the centrifugal force applied through the adhesive can concentrate on part of the rotor core
Data Source
AI summary
A rotor has reduced weight. A hammer drill includes a motor including a stator and a rotor rotatable relative to the stator. The rotor includes a rotor core having a first space, and a permanent magnet fixed on the rotor core.