Reciprocating Mower Unit with Reduction Gear and Crank Mechanism

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Solution Overview

Problem

Existing reciprocating mowers lack ergonomic design and versatility, making them less user-friendly and efficient for various vegetation cutting tasks, particularly in scenarios where vibration and compatibility with different drive units are concerns.

Innovation Solution

A reciprocating mower unit with a reduction gear and crank mechanism that converts high-speed input rotation into lower-speed oscillating motion for mowing blades, featuring a coupling interface for interchangeable connection with different drive units and a modular system that includes a clearing saw unit, along with a four-bar linkage and grounding body to reduce vibrations and enhance usability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a reciprocating mower uses a fixed drive unit connection, then the structural simplicity is maintained, but the versatility and adaptability to different drive units is reduced

Engineering Contradiction:
Improvecompatibility with different drive unitsVSAvoidcoupling interface structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The coupling interface is designed with universal compatibility, allowing the reciprocating mower unit to connect to different types of drive units through a standardized spline connection system. The input shaft with external splines can mate with various drive unit output shafts, enabling one mower unit to serve multiple applications with different power sources.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The mower system is divided into separable components: a reciprocating mower unit and a drive unit that can be independently connected or disconnected. The coupling interface enables this segmentation while maintaining functional connectivity, allowing users to detach the mower unit from incompatible or unavailable drive units.

Inventive Principle:
Principle #1Segmentation

2Volume of moving object

If the reduction gear uses a single-stage design, then the device complexity is reduced, but the ability to achieve high reduction ratio with compact volume is limited

Engineering Contradiction:
Improvereduction gear sizeVSAvoidreduction gear structure
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The two-stage reduction gear employs a nested arrangement where the second reduction stage is positioned within or alongside the first stage. The pinion gear of the second stage meshes with the second gear, creating a compact nested structure that achieves high reduction ratio in a limited space without requiring a large single-stage gear system.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The two reduction stages are combined into a single integrated gear housing structure. The first reduction (transmission shaft to intermediate shaft) and second reduction (intermediate shaft to output shaft) operate simultaneously within the same spatial envelope, merging multiple functional elements into a compact unified system.

Inventive Principle:
Principle #5Merging (Combining)

3Productivity

If the mower unit is designed for high-speed operation, then the productivity is improved, but the vibrations and user comfort deteriorate

Engineering Contradiction:
Improvemowing speedVSAvoidvibrations
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The reduction gear acts as an intermediary between the high-speed input shaft and the lower-speed oscillating output. By introducing intermediate reduction stages, the system transforms high-speed rotation into controlled oscillating motion at reduced speed, filtering out harmful vibrations while maintaining productive cutting speed.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the operational parameters through the reduction gear train. The input shaft rotates at high speed, but through two stages of gear reduction, the output shaft achieves the appropriate speed and oscillation characteristics for efficient mowing with minimized vibrations, effectively transforming speed and motion type parameters.

Inventive Principle:
Principle #35Parameter changes

4Adaptability or versatility

If the reciprocating mower unit is made modular with interchangeable coupling, then the versatility is improved, but the device complexity increases

Engineering Contradiction:
Improveinterchangeable drive unit connectionVSAvoidmodular system structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The modular design employs a universal coupling interface that can connect to different drive unit types. The standardized spline connection and clamping mechanism create a universal interface that maintains functional equivalence across different configurations, reducing the need for multiple specialized mower units.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 enhances the ergonomic design and versatility of the mower, reduces vibrations, and allows for interchangeable use with different drive units, improving user experience and efficiency across various vegetation cutting tasks.

Implementation Method 1

a reduction gear arranged within the housing, the reduction gear being configured to receive an input rotary motion from the transmission shaft at a first, relatively higher, rotation speed, and deliver an output rotary motion to a gear output shaft at a second, relatively lower, rotation speed

Methodology Applied
Scientific EffectGear mechanism: Gear

Implementation Method 2

a crank mechanism arranged within the housing, the crank mechanism being configured to convert the output rotary motion of the gear output shaft to an oscillating motion of a pair of mowing blades oscillating in mutual anti-phase about a common oscillation axis

Methodology Applied
Scientific EffectCrank mechanism: Crankshaft

Implementation Method 3

a four-bar linkage and grounding body to reduce vibrations and enhance usability

Methodology Applied
Scientific EffectFour-bar linkage: Four-Bar Linkage

Data Source

PatentEP3927140B1Reciprocating mower unit, system, and method
Publication Date: 2024.11.13 HUSQVARNA AB
  • EP3927140B1 patent drawingFigure 1
  • EP3927140B1 patent drawingFigure 2
  • EP3927140B1 patent drawingFigure 3a~3b

AI summary

A reciprocating mower unit (14) comprises a reduction gear (54) and a crank mechanism (56) arranged within a housing (24). The reduction gear (54) receives input rotary motion from a transmission shaft at a first, relatively higher, rotation speed, and deliver an output rotary motion to a gear output shaft (58) at a second, relatively lower, rotation speed, whereas the crank mechanism (56) converts the output rotary motion of the gear output shaft (58) to an oscillating, anti-phase motion of a pair of mowing blades (32a, 32b) about a common oscillation axis (Al). The reciprocating mower unit (14) comprises an input shaft (48) provided with a coupling interface (49) for releasably coupling the input shaft (48) to the transmission shaft.