Wheel Hub Drive for Compact Self-Propelled Mowers
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Solution Overview
Problem
Existing smart mowers have large volumes and weights, making them inconvenient to use and move, due to complex drive assemblies between the traveling electric motor and wheels, which increases installation complexity and reduces user experience.
Innovation Solution
A self-propelled device with a wheel hub motor integrally disposed in the traveling wheel, eliminating the need for a gearbox and simplifying the structure by directly driving the wheel, while a control circuit with a field-oriented control system adjusts the rotational speed of the wheel hub motor for efficient movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traveling electric motor and drive assembly (gear mechanism) are used to drive the traveling wheels, then the mower can achieve reliable motion, but the body volume and weight increase, and installation complexity increases
Solution Approach 1:
The patent merges the motor and wheel into a single integrated wheel hub motor assembly. The motor is mounted directly on the wheel hub, eliminating the need for separate drive assemblies and gear mechanisms. This integration reduces body volume while maintaining reliable motion through direct drive capability.
Solution Approach 2:
The patent extracts and eliminates the intermediate drive assembly (gear mechanism) from the system. By using a wheel hub motor that directly drives the wheel, the complex transmission components are removed, reducing both volume and installation complexity while preserving motion reliability.
2Reliability
If a traveling electric motor and drive assembly (gear mechanism) are used to drive the traveling wheels, then the mower can achieve reliable motion, but the body weight increases
Solution Approach 1:
The patent combines the motor and wheel into a single integrated unit, eliminating the weight of intermediate drive components. The wheel hub motor directly drives the wheel without requiring separate gear mechanisms, reducing overall body weight while maintaining motion reliability through direct coupling.
Solution Approach 2:
The patent removes the drive assembly (gear mechanism) from the system by using a wheel hub motor with direct drive capability. This extraction of unnecessary components significantly reduces body weight while preserving reliable motion through the simplified direct drive path.
3Power
If a wheel hub motor with large radial length is used to provide sufficient torque, then the output power requirement is met, but the device dimension increases
Solution Approach 1:
The patent addresses the radial length constraint by optimizing the motor's dimensional distribution. Instead of increasing radial length, the design accepts an increased axial thickness (up to 3.5 cm) to provide sufficient torque and power output, effectively redistributing the dimensional requirements to a different spatial dimension.
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 reduces the overall dimension and weight of the device, simplifies the assembly process, and improves user experience by enabling easier handling and operation with efficient low-speed control.
Implementation Method 1
a wheel hub motor integrally disposed in the traveling wheel
Implementation Method 2
a control circuit with a field-oriented control system adjusts the rotational speed of the wheel hub motor
Data Source
AI summary
A self-propelled device includes a cutting assembly for cutting vegetation; a body for supporting the cutting assembly; and a traveling system for driving the body to move. The traveling system includes at least a traveling wheel; and a wheel hub motor integrally disposed in the traveling wheel. Along an axial direction of the traveling wheel, the first external dimension of the self-propelled device is greater than or equal to 0.2 m and less than or equal to 1.5 m. Along a direction perpendicular to the axial direction of the traveling wheel, the second external dimension of the self-propelled device is greater than or equal to 0.5 m and less than or equal to 1.5 m.