Outrunner Chainsaw Layout for High Power-to-Weight Cutting
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Solution Overview
Problem
Chainsaws with high output power have a large volume and heavy weight, making them difficult to handle and unsuitable for prolonged use.
Innovation Solution
A chainsaw design with a power supply device and a tool body that includes a housing, a chain, a guide plate, a drive device with a motor, and a brake device, where the motor-to-mass ratio is optimized between 0.5 kW/kg and 2.0 kW/kg, and features a brushless outrunner motor, a brake device with a brake belt for mechanical braking, and an integrated lubrication system to reduce volume and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the output power of the chainsaw is increased to improve cutting efficiency, then the cutting efficiency is improved, but the volume and weight of the chainsaw increase, making it difficult to hold and unsuitable for prolonged use
Solution Approach 1:
The patent applies parameter changes by optimizing the motor power-to-mass ratio to a specific range (0.5-2.0 kW/kg), selecting appropriate battery pack capacities (20-100 Wh), and adjusting the volumetric power density (2.0-5.0 kW/L) to achieve the best balance between cutting efficiency and portability. This resolves the contradiction by finding optimal parameter values rather than simply increasing power indefinitely.
Solution Approach 2:
The patent implements dynamics through adjustable power modes (first power mode and second power mode) that allow the motor to operate at different power levels based on cutting requirements. The system can dynamically switch between power levels, enabling high power when needed for difficult cuts and lower power for routine work, thus maintaining cutting efficiency while reducing average weight burden on the user.
2Productivity
If the output power of the chainsaw is increased to improve cutting efficiency, then the cutting efficiency is improved, but the volume of the chainsaw increases, making it difficult to hold
Solution Approach 1:
The patent applies parameter changes by optimizing the volumetric power density to a specific range (2.0-5.0 kW/L), which allows the chainsaw to achieve high cutting efficiency within a compact volume. This is accomplished by selecting appropriate motor dimensions, battery pack sizes, and overall housing configuration that maximize power density while maintaining ergonomic handling dimensions.
3Productivity
If the motor power is increased to maintain high power-to-weight ratio, then the cutting efficiency is improved, but the energy consumption increases, requiring larger battery packs
Solution Approach 1:
The patent implements dynamics through adjustable power modes that allow the motor to operate at different power levels based on cutting requirements. The system can dynamically switch between a first power mode (higher power) and a second power mode (lower power), enabling high cutting efficiency when needed while conserving battery energy during routine operations, thus resolving the contradiction between maintaining high power-to-weight ratio and managing battery capacity.
Solution Approach 2:
The patent applies periodic action through intermittent high-power bursts followed by lower-power operation. During difficult cutting tasks, the motor operates at high power temporarily, then transitions to lower power during less demanding phases, creating a periodic pattern of power usage that maintains cutting efficiency while averaging down the overall energy consumption and extending battery life.
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 design achieves a higher power-to-weight ratio, enhancing user handling and enabling longer use without compromising cutting efficiency.
Implementation Method 1
a brake device configured to brake the drive device
Data Source
AI summary
A chainsaw includes a tool body and a power supply device, where the power supply device is configured to provide a power source for the tool body. The tool body includes: a housing; a chain configured to perform a cutting function; a guide plate for supporting and guiding the chain; a drive device, where the drive device is at least partially disposed in an accommodating space formed by the housing and includes a motor configured to drive the chain; and a brake device configured to brake the drive device. The tool body includes a main machine. The main machine includes at least the housing, the drive device, and the brake device. The motor is an outrunner. The power-to-mass density of the main machine is greater than or equal to 0.5 kW/kg and less than or equal to 2.0 kW/kg.