In-Wheel Drive Layout for Compact and Stable Garden Tools
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Solution Overview
Problem
Garden tools, such as mowers, face challenges with space occupancy by motors and reduction gearboxes, affecting stability and heat dissipation, and rely on mechanical brakes that require operator intervention and frequent maintenance.
Innovation Solution
A garden tool design that integrates a driving unit with a planetary reducer mounted in the traveling wheel, incorporating a hub motor and electromagnetic braking mechanism to reduce lateral width, improve stability, and enhance heat dissipation through airflow cooling, while eliminating the need for mechanical brakes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a motor and reduction gearbox are used to provide power and torque, then the garden tool can meet work needs, but the lateral assembly space is occupied and the center of gravity cannot be positioned ideally, affecting stability
Solution Approach 1:
The patent merges the motor and reduction gearbox into an integrated driving unit, where the motor is positioned inside the gearbox housing. This combination reduces the overall lateral space occupied while maintaining the required torque output capability, directly resolving the contradiction between power delivery and space occupancy.
Solution Approach 2:
The motor is nested within the reduction gearbox housing, with the motor shaft connected to the input shaft of the gearbox. This nesting arrangement allows the motor to be housed within the existing gearbox structure, minimizing additional lateral space requirements while preserving both motor power and gear reduction functionality.
2Productivity
If a motor and reduction gearbox are used to provide power, then the garden tool can operate, but the installed modules occupy space and the center of gravity positioning is compromised, affecting stability
Solution Approach 1:
The patent repositions the driving unit vertically by placing the motor inside the gearbox housing, utilizing the vertical dimension rather than lateral space. This dimensional shift allows the center of gravity to be lowered to an ideal position, improving stability while maintaining full work capability.
3Reliability
If mechanical braking structures are used, then the garden tool can be braked, but operator intervention is required and brake pads wear down, requiring frequent replacement
Solution Approach 1:
The patent replaces the mechanical braking system with an electromagnetic braking mechanism. The electromagnetic brake uses electromagnetic fields to apply braking force, eliminating the need for mechanical brake pads that wear down. This substitution maintains reliable braking function while eliminating the need for frequent pad replacement and operator intervention.
Solution Approach 2:
The electromagnetic braking mechanism operates automatically based on control signals, providing self-service braking without requiring operator intervention. The system can autonomously apply and release the brake as needed, eliminating the manual operation required by mechanical braking systems.
4Volume of stationary object
If limited installation space is available, then the garden tool structure is compact, but sufficient heat dissipation channels cannot be reserved, resulting in poor heat dissipation
Solution Approach 1:
The patent combines the heat dissipation function with the existing gearbox housing structure. The housing serves dual purposes as both the gearbox enclosure and the heat dissipation component, with integrated cooling fins or channels. This merging avoids adding separate heat dissipation components that would increase lateral space requirements.
Solution Approach 2:
The gearbox housing is designed to perform multiple functions: containing the gears, supporting the motor, and dissipating heat. By making the housing multi-functional, the patent achieves effective heat dissipation without occupying additional installation space, as the same structure serves multiple purposes.
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 reduces the overall size of the garden tool, improves stability by lowering the center of gravity, and ensures automatic braking when powered off, reducing the risk of skidding and extending equipment lifespan through effective heat dissipation.
Implementation Method 1
a planetary reducer mounted in the traveling wheel... a first sun gear is provided on the core shaft and is coaxially fixed with the core shaft; a first planet gear carrier rotatably connected to the core shaft, where a first planet gear and a second sun gear are provided on the first planet gear carrier, the first planet gear is rotatably connected to the first planet gear carrier, the first planet gear engages with the first sun gear
Implementation Method 2
incorporating a hub motor and electromagnetic braking mechanism to reduce lateral width, improve stability, and enhance heat dissipation through airflow cooling, while eliminating the need for mechanical brakes
Implementation Method 3
enhance heat dissipation through airflow cooling
Data Source
AI summary
This application belongs to the field of a garden tool and specifically relates to a garden tool including: a body; at least two traveling wheels located on two sides of the body; and a driving unit. The driving unit is installed inside the traveling wheel. In the present application, the driving unit is installed inside the rim. Therefore, the overall axial dimension of the traveling unit is reduced, the lateral width of the garden tool such as a mower is reduced. Under the same width conditions, more lateral space is available for the garden tool, allowing for the installation of structures such as battery compartments and standing platforms. This design lowers the center of gravity of the garden tool like a mower, thereby enhancing their stability.