Variable Speed Control for Electric Lawn Mower Cutter Blades

Solution Overview

Problem

Conventional electric lawn mowers lack the ability to variably set the rotational speed of the cutter blade, making operation less efficient and accurate.

Innovation Solution

Incorporating a speed setting device on the handle with multiple switches and operation buttons of different sizes to allow for adjustable rotational speed settings of the work unit electric motor, enabling easy and accurate selection of desired speed settings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If multiple switches with identical operation buttons are used for speed setting, then the device complexity is reduced, but the ease of operation deteriorates because the operator cannot easily distinguish which button corresponds to which speed

Engineering Contradiction:

Improvestructure of speed setting deviceVSAvoidease and accuracy of speed selection

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The operation buttons are given different local qualities in terms of size. Specifically, the operation button for higher rotational speed is larger than the operation button for lower rotational speed. This local differentiation allows the operator to easily distinguish and select the appropriate speed setting without confusion, while still maintaining a relatively simple overall device structure.

Inventive Principle:

Principle #3Local quality

2Device complexity

If only on/off switching is provided for the cutter blade, then the device complexity is minimized, but the productivity deteriorates because variable rotational speed settings cannot be achieved

Engineering Contradiction:

Improvespeed control mechanismVSAvoidmowing efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent introduces dynamic speed control capability by providing multiple switches for variable rotational speed settings. The system transitions from a static on/off state to a dynamic multi-level speed control system, allowing the cutter blade to operate at different rotational speeds (first rotational speed and second rotational speed) according to operational needs, thereby improving productivity without excessive complexity.

Inventive Principle:

Principle #15Dynamics

3Ease of operation

If operation buttons of different sizes are used for different speed settings, then the ease of operation is improved through visual selection, but the ease of manufacture deteriorates due to more complex button fabrication

Engineering Contradiction:

Improvevisual selection of speed settingVSAvoidmanufacturing of operation buttons

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The operation buttons are given different local qualities in terms of size. Specifically, the operation button for higher rotational speed is larger than the operation button for lower rotational speed. This local differentiation allows the operator to easily distinguish and select the appropriate speed setting without confusion, while still maintaining a relatively simple overall device structure.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11337369B2Electric power equipment

Publication Date: 2022.05.24 HONDA MOTOR CO LTD

AI summary

To enable the rotational speed of the cutter blade to be set variably and to allow the operation therefor to be performed with ease and accuracy, multiple switches (74, 76) for setting the rotational speed of the cutter blade electric motor (6) to mutually different rotational speeds, and multiple operation buttons (78, 80) provided for the respective switches (74, 76) are included on a handle (20), wherein the operation buttons (78, 80) have operation parts (78A, 80A) provided with mutually different sizes.