Inverter Positioning for Cordless Power Tool Stability
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Solution Overview
Problem
Conventional power tools driven by AC motors are limited to use within the reach of an external power source due to their reliance on a connected power cord, restricting their operational flexibility.
Innovation Solution
A power tool configuration that includes a housing, motor, end tool, battery pack, and inverter, where the inverter converts direct-current voltage from the battery pack to alternating-current voltage, allowing the tool to operate independently of an external power source, with the inverter positioned above the motor to enhance stability and prevent damage during use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the power tool is connected to an external power source via a power cord, then the motor can be driven by stable AC power, but the power tool can only be used within the reach of the power cord
Solution Approach 1:
The power supply system is segmented into separate functional modules: a DC battery pack and an AC inverter. The inverter is detachably mounted on the housing, allowing it to be separated from the battery pack. This segmentation enables flexible power supply configurations - the inverter can be attached to the battery pack for cordless operation or connected to external AC power sources, thus resolving the contradiction between usage flexibility and system complexity.
Solution Approach 2:
The inverter serves multiple functions: it can convert DC voltage from the battery pack to AC voltage for motor operation, or it can be connected to external AC power sources. This multi-functionality allows the power tool to operate in multiple modes (cordless and corded), enhancing adaptability while using a single versatile component rather than separate systems.
2Object-affected harmful factors
If the inverter is positioned on the lower side portion of the housing, then the power tool structure is compact, but the inverter may hit the ground surface, stones, and other objects during use
Solution Approach 1:
The inverter is designed with detachable mounting on the housing, allowing its position to be dynamically adjusted or removed. This dynamic configuration enables the inverter to be positioned on the upper side portion during operation to avoid ground contact and damage, while still being integrated with the housing structure when needed, thus resolving the contradiction between protection and structural layout.
3Ease of operation
If the inverter has a relatively large weight, then the end tool can be urged downward improving operability and stability, but the power tool may fall over rearward
Solution Approach 1:
The inverter is asymmetrically positioned on the upper side portion of the housing rather than being centrally or lower-mounted. This asymmetric placement creates a specific weight distribution that urges the end tool downward for stability during operation. The position is carefully selected to achieve the desired downward force on the cutting tool while maintaining overall balance and preventing rearward tipping.
Solution Approach 2:
The inverter is positioned in the vertical dimension (upper side portion) rather than being distributed horizontally. This vertical placement uses gravity to create downward force on the end tool, improving contact stability with the ground. The vertical positioning resolves the contradiction by using gravitational force in the vertical dimension to achieve stability without compromising horizontal balance.
4Stability of the object's composition
If the inverter is located between the motor and the end tool, then weight balance can be improved, but the inverter may interfere with motor operation
Solution Approach 1:
The inverter is detachably mounted on the housing in a nested configuration where it can be attached when needed and removed when not required. This nesting approach allows the inverter to be positioned in the upper side portion close to the motor assembly for optimal weight balance, while its detachable nature prevents permanent interference with motor operation or maintenance activities.
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
Enables the power tool to be used at locations away from an external power source, improves operability by maintaining tool stability and preventing damage from ground contact, and allows for easier maintenance and detachment of components.
Implementation Method 1
The inverter is disposed on the upper side portion and at a position higher than the motor and configured to convert the direct-current voltage outputted from the battery pack into alternate-current voltage and to supply the motor with alternate-current power
Data Source
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AI summary
The present invention provides a power tool that can be used at a position away from the external power source. The power tool includes a housing, a motor, an end tool, a battery pack, and an inverter. The housing has an upper side portion and a lower side portion. The motor is supported by the housing and driven by alternate-current power. The end tool is supported by the housing and rotatably driven by the motor. The battery pack outputs direct-current voltage. The inverter is disposed on the upper side portion and at a position higher than the motor and configured to convert the direct-current voltage outputted from the battery pack into alternate-current voltage and to supply the motor with alternate-current power.