Pressure-Regulated Hydraulic Weight Compensation for Haymaking Machines

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Solution Overview

Problem

Agricultural machinery with hydropneumatic pressure accumulators for lifting heavy working units faces issues of inconsistent weight distribution, energy inefficiency, and safety hazards due to continuous pressurized oil requirements, leading to potential damage to plant covers and increased operational costs.

Innovation Solution

An agricultural machine with a lightening device using a pressure regulator that maintains constant weight distribution by adjusting hydraulic fluid flow between a relief cylinder and a pump or reservoir based on pressure, eliminating the need for hydropneumatic accumulators and reducing energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If hydropneumatic pressure accumulators are used to lighten the working unit, then the weight transfer is achieved, but the weight distribution becomes inconsistent and safety hazards arise

Engineering Contradiction:
Improveweight transferVSAvoidweight distribution consistency
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The patent removes the hydropneumatic pressure accumulator from the system entirely, replacing it with a simpler hydraulic circuit using a relief cylinder, pressure regulator, pump, and reservoir. This extraction of the problematic component eliminates the source of inconsistent weight distribution and safety hazards while preserving the essential weight transfer function.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The pressure regulator in the patent provides automatic feedback control by monitoring hydraulic fluid pressure and adjusting the relief cylinder's force accordingly. When pressure exceeds a set threshold, the regulator opens to release fluid, reducing pressure and lightening force. This self-regulating feedback mechanism ensures consistent weight distribution without requiring complex electronic controls or safety accumulators.

Inventive Principle:
Principle #23Feedback

2Force

If pressure accumulators are used for lightening, then weight transfer is achieved, but energy consumption increases due to continuous pressurized oil requirements

Engineering Contradiction:
Improveweight transferVSAvoidenergy consumption
Core Design Contradiction:
ForceVSUse of energy by moving object

Solution Approach 1:

The hydraulic pump operates periodically rather than continuously, activating only when the pressure regulator requires pressure buildup to maintain the lightening force. The relief cylinder maintains constant force by releasing pressure periodically when the set threshold is exceeded, eliminating the need for continuous pressurized oil flow and reducing energy consumption significantly.

Inventive Principle:
Principle #19Periodic action

3Force

If pressure accumulators are used for lightening, then weight transfer is achieved, but device complexity and maintenance requirements increase

Engineering Contradiction:
Improveweight transferVSAvoidsystem complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

By removing the hydropneumatic pressure accumulator and electronic control components, the patent simplifies the system into a purely hydraulic circuit with a relief cylinder, pressure regulator, pump, and reservoir. This reduction in components decreases assembly complexity, lowers costs, and eliminates the need for regular inspections and safety valve additions required by pressure accumulators.

Inventive Principle:
Principle #2Taking out (Extraction)

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 ensures consistent weight transfer, reduces energy consumption, minimizes damage to plant covers, and simplifies maintenance by avoiding continuous pressurized oil use and electronic controls, thus enhancing operational efficiency and safety.

Implementation Method 1

the relief device comprises a pressure regulator connected to an active chamber of the relief cylinder by a first line, the pressure regulator occupying, when the pressure in the first line is lower than a set value, a first position in which it allows the circulation of hydraulic fluid between the first line and a second line connecting the pressure regulator with a hydraulic pump in the working configuration of the machine, the pressure regulator occupying, when the pressure in the first line is higher than the set value, a second position in which it allows a circulation of hydraulic fluid between the first line and a third line connecting the pressure regulator with a reservoir in the working configuration of the machine

Methodology Applied
Scientific EffectHydraulic pressure regulation: Pressure Gradient

Implementation Method 2

a lightening device comprising at least one lightening cylinder connected to the chassis on one side and to the working unit on the other side, the lightening cylinder being able to transfer, in the working configuration, at least part of the weight of the working unit onto the chassis

Methodology Applied
Scientific EffectHydraulic force: Hydraulic Press

Data Source

PatentEP4256916B1Haymaking machine with improved hydraulic weight compensation and method for its operation
Publication Date: 2025.10.08 KUHN SA
  • EP4256916B1 patent drawingFigure 1
  • EP4256916B1 patent drawingFigure 2~3
  • EP4256916B1 patent drawingFigure 4~5A

AI summary

The invention relates to an agricultural machine (1) intended to be coupled to a tractor vehicle (15) and comprising a working unit (3) connected to a chassis relative to which the working unit (3) is movable. The machine (1) can be in a working configuration in which the working unit rests at least partially on the ground and in a transport configuration in which the working unit (3) is raised off the ground. The machine includes a weight-relieving device (9) comprising at least one weight-relieving cylinder connected to the chassis on one side and to the working unit on the other side. In the working configuration, the weight-relieving cylinder (9) can transfer at least part of the weight of the working unit to the chassis.