Rotary Member Torque Control for Uniform Lawn Cutting

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Solution Overview

Problem

Existing work machines, such as lawn mowers, face challenges in improving efficiency and performance due to variations in cutting height and uneven lawn mowing resulting from the driving mode of the working mechanism.

Innovation Solution

A work machine equipped with a control unit that adjusts the output of the rotary member during one rotation, increasing torque in specific ranges to maintain consistent cutting height and improve cutting efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the drive source operates at constant output during rotation, then the structure is simple, but the cutting height uniformity deteriorates

Engineering Contradiction:

Improvecontrol system complexityVSAvoidcutting height uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by transitioning from constant output operation to dynamic output adjustment. The control unit varies the output of the rotary member during one rotation cycle, increasing torque in specific angular ranges (e.g., when cutting portions contact the lawn) to maintain consistent cutting height. This dynamic adjustment resolves the contradiction by making the system adaptive to the varying work load throughout the rotation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the output parameter (torque) of the rotary member as a function of rotational position. By adjusting the torque parameter in different angular ranges during rotation, the system achieves uniform cutting height. This parameter change approach allows the drive source to adapt its output characteristics to the specific requirements at different stages of the rotation cycle.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If torque is increased in specific ranges during rotation, then cutting height uniformity improves, but power consumption increases

Engineering Contradiction:

Improvecutting height uniformityVSAvoidpower consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies partial action by increasing torque only in specific angular ranges during rotation, rather than maintaining high torque throughout the entire cycle. The control unit adjusts output selectively when cutting portions contact the lawn, and reduces output when they do not. This partial application of increased torque achieves the desired cutting uniformity while minimizing overall power consumption compared to constant high-output operation.

Inventive Principle:

Principle #16Partial or excessive action

3Use of energy by moving object

If the rotary member operates without output variation, then energy consumption is reduced, but work performance deteriorates

Engineering Contradiction:

Improveenergy consumptionVSAvoidwork performance

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The patent implements periodic action by varying the output of the rotary member in a cyclic manner corresponding to its rotation. The control unit periodically increases torque when cutting portions contact the lawn and reduces it when they don't, creating a rhythmic pattern of high and low output that synchronizes with the rotation cycle. This periodic variation improves work performance while managing energy consumption more effectively than constant operation.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS12201052B2Work machine with a rotary member and torque control therefor

Publication Date: 2025.01.21 HONDA MOTOR CO LTD

AI summary

A work machine comprises, a drive source, a working unit that includes a rotary member rotated by the drive source and performs a predetermined work by rotation of the rotary member, and a control unit that controls the drive source so that output of the rotary member partially takes different values in one rotation of the rotary member.