Lawn Mower Cutting Blade Motor Reverse Rotation Grass Removal

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Solution Overview

Problem

Existing electric lawn mowers face performance deterioration when grass accumulates at the cutting blades, leading to inefficient mowing.

Innovation Solution

Incorporating a mode selector and processing circuitry that allows the cutting blade motor to change rotational frequency or torque significantly or reverse direction in a 'grass removal mode' to brush away accumulated grass, in addition to normal and silent mowing modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the cutting blade motor operates continuously in normal rotation direction, then lawn mowing is performed effectively, but grass accumulates on the cutting blade causing performance deterioration

Engineering Contradiction:

Improvelawn mowing efficiencyVSAvoidmowing performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system alternates between normal cutting operation and reverse rotation for grass removal. The mode selector switches between normal lawn mowing mode and grass removal mode, creating periodic action that prevents grass accumulation while maintaining cutting efficiency

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The cutting blade motor rotates in reverse direction during grass removal mode to brush away accumulated grass. This inversion of rotation direction enables the blade to function as a brush, effectively removing grass buildup that occurs during normal operation

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If the rotational frequency or torque changes significantly to remove grass, then grass accumulation is prevented, but energy consumption increases

Engineering Contradiction:

Improvegrass removal effectivenessVSAvoidmotor energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The grass removal operation is performed periodically rather than continuously. The mode selector enables switching between normal operation and grass removal mode, allowing significant rotational changes only when needed to remove accumulated grass, thereby reducing overall energy consumption

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The cutting blade motor serves dual functions: cutting grass during normal operation and removing accumulated grass through reverse rotation. This self-service capability eliminates the need for separate mechanisms, reducing overall system energy requirements while maintaining effective grass removal

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS20240276913A1Lawn mower

Publication Date: 2024.08.22 KAWASAKI MOTORS LTD

AI summary

A lawn mower includes: a cutting blade motor that drives a cutting blade; a mode selector that selects one of modes including a normal lawn mowing mode and a grass removal mode in which grass accumulated at the cutting blade is brushed away; and processing circuitry configured to control the cutting blade motor in the mode selected by the mode selector. In the normal lawn mowing mode, the cutting blade motor is controlled so as to rotate in a normal rotation direction at a predetermined rotational frequency or with a predetermined torque. In the grass removal mode, the cutting blade motor is controlled such that the rotational frequency or torque of the cutting blade motor changes more significantly than the rotational frequency or torque of the cutting blade motor in the normal lawn mowing mode, or the cutting blade motor rotates in a reverse rotation direction.