Variable-Frequency Electric Drive for Hay Rake Rotors

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Solution Overview

Problem

Existing hay-making machines with complex, branched drive systems are heavy and costly due to the use of cardan shafts and gears, which complicates the drive energy distribution to multiple rotors.

Innovation Solution

A hay-making machine equipped with a variable-frequency electric drive system using separate frequency converters for each raking rotor, which can be powered by an external or on-board generator, allowing for flexible and efficient energy distribution without cardan shafts and gears, enabling individual control and overload protection of each rotor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a complex branched drive system with cardan shafts and gears is used to distribute drive energy to multiple rotors, then the drive system can power multiple rotors simultaneously, but the weight and cost of the machine increases significantly

Engineering Contradiction:
Improvedrive energy distribution capabilityVSAvoidmachine weight
Core Design Contradiction:
PowerVSWeight of moving object

Solution Approach 1:

The patent divides the drive system into multiple independent electric motor units, with each rotor having its own dedicated motor. This segmentation eliminates the need for a complex centralized drive system with cardan shafts and gears, significantly reducing weight while maintaining the capability to power multiple rotors simultaneously. Each motor unit operates independently, allowing flexible power distribution without mechanical coupling components.

Inventive Principle:
Principle #1Segmentation

2Power

If a complex branched drive system with cardan shafts and gears is used to distribute drive energy to multiple rotors, then the drive system can power multiple rotors simultaneously, but the cost of the machine increases due to numerous components

Engineering Contradiction:
Improvedrive energy distribution capabilityVSAvoidmanufacturing cost
Core Design Contradiction:
PowerVSEase of manufacture

Solution Approach 1:

By segmenting the drive system into independent electric motor units for each rotor, the patent eliminates expensive mechanical components such as cardan shafts, branching gears, and associated maintenance infrastructure. This modular approach simplifies manufacturing, reduces part count, and lowers overall system cost while maintaining full drive energy distribution capability across multiple rotors.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent replaces the mechanical drive system (cardan shafts and gears) with an electrical drive system using independent electric motors for each rotor. This substitution eliminates complex mechanical power transmission components, reducing both manufacturing cost and maintenance requirements while preserving the ability to distribute drive energy to multiple rotors simultaneously.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Power

If cardan shafts and gears are used in the drive system, then drive energy can be distributed to multiple rotors, but the device complexity increases due to numerous components

Engineering Contradiction:
Improvedrive energy distribution capabilityVSAvoiddrive system complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The patent segments the drive system into independent electric motor units, one for each rotor, eliminating the need for a complex centralized mechanical drive system. This segmentation removes cardan shafts, branching gears, and associated complexity, while maintaining the capability to distribute drive energy to multiple rotors through independent electrical control of each motor unit.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent replaces the complex mechanical drive system (cardan shafts and gears) with a simplified electrical drive system using independent electric motors for each rotor. This substitution dramatically reduces device complexity by eliminating mechanical power transmission components while preserving full drive energy distribution capability through electrical control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Power

If a centralized drive system with cardan shafts is used, then multiple rotors can be powered, but maintenance requirements increase due to gearbox and cardan shaft maintenance

Engineering Contradiction:
Improvedrive energy distribution capabilityVSAvoidmaintenance requirements
Core Design Contradiction:
PowerVSEase of repair

Solution Approach 1:

By segmenting the drive system into independent electric motor units for each rotor, the patent eliminates centralized mechanical components such as cardan shafts and gearboxes that require maintenance. Each motor unit is self-contained and maintenance-free, allowing multiple rotors to be powered without the maintenance burden associated with mechanical power transmission systems.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent replaces the mechanical drive system (cardan shafts and gearboxes requiring maintenance) with an electrical drive system using independent electric motors for each rotor. This substitution eliminates maintenance requirements for mechanical power transmission components while maintaining the capability to distribute drive energy to multiple rotors through electrical control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

This solution reduces weight and cost, simplifies the drive technology, allows for flexible operation, and prevents collisions by enabling precise control of rotor speed and position, while eliminating the need for gearbox and cardan shaft maintenance.

Implementation Method 1

The on-board generator can then be driven either by the PTO shaft of the towing vehicle or, for example, by the hydraulic power supply of the towing vehicle and then by a hydraulic motor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the drive system comprising frequency converters and each raking rotor is assigned a separate frequency converter

Methodology Applied
Scientific EffectPower electronics conversion:

Implementation Method 3

variable-frequency electric drive system for driving electric motors for the raking rotors

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentEP2305021B1Hay rake
Publication Date: 2015.01.07 CLAAS SAULGAU GMBH
  • EP2305021B1 patent drawingFigure 1
  • EP2305021B1 patent drawingFigure 2

AI summary

The haymaking machine (1) has a circulating gyro (3) propelled around a vertical axis of an electrical driving motor. The haymaking machine has a frequency-variable electrical drive system for driving the circulating gyro. The electrical drive system is coupled to an external generator (5) of a towing vehicle (2).