Hydraulic Three-Point Lift Pressure Control for Uniform Soil Cultivation

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Solution Overview

Problem

Existing hydraulic three-point linkages on agricultural tractors result in undesirable variations in soil cultivation due to the reliance on implement weight for contact pressure, leading to inconsistent soil cultivation results.

Innovation Solution

A double-acting hydraulic cylinder system with a control valve arrangement, including a 3/2-way pilot valve and a 3/2-way main valve, allows for precise control of target pressure to enhance contact pressure and guide implements along defined contours, using feedback loops to maintain consistent operation and avoid uncontrolled pressure buildup.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single-acting hydraulic cylinder is used, then the structure is simpler, but the contact pressure varies undesirably depending on soil conditions

Engineering Contradiction:
Improvehydraulic cylinder structureVSAvoidsoil cultivation consistency
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent applies dynamics by transitioning from a static single-acting cylinder to a dynamic double-acting cylinder system. The control valve arrangement dynamically adjusts hydraulic pressure in both working chambers based on detected soil conditions, enabling real-time adaptation of contact pressure to maintain consistent soil cultivation across varying soil states.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by modifying the hydraulic pressure parameters in the working chambers of the double-acting cylinder. The control system varies the pressure differential between chambers to actively control implement contact pressure, transforming the system from passive weight-dependent pressure to active pressure-controlled operation.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If the implement weight alone is used for contact pressure, then no additional control is needed, but the soil cultivation result becomes inconsistent

Engineering Contradiction:
Improvecontrol system simplicityVSAvoidsoil cultivation uniformity
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent implements feedback control through a control valve arrangement that detects actual soil conditions and adjusts hydraulic pressure accordingly. The system continuously monitors cultivation results and modifies the pressure differential across the hydraulic cylinder chambers to maintain desired contact pressure, ensuring consistent soil cultivation uniformity.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces the purely mechanical weight-dependent pressure system with a hydraulic control system. Instead of relying on implement weight alone, the system uses hydraulic pressure differential controlled by a valve arrangement to actively manage contact pressure, achieving precise control over soil cultivation consistency.

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

3Reliability

If a double-acting hydraulic cylinder with pressure control is implemented, then contact pressure can be precisely controlled, but the device complexity increases

Engineering Contradiction:
Improvecontact pressure consistencyVSAvoidcontrol valve arrangement
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The control valve arrangement serves multiple functions: it controls pressure differential for contact pressure regulation, adapts to varying soil conditions, and maintains consistent cultivation results. This multi-functionality justifies the increased device complexity by consolidating multiple control tasks into a single integrated system.

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

4Stability of the object's composition

If downward force is applied to counteract implement floatation, then guidance along surface contours is improved, but the system requires more complex pressure control

Engineering Contradiction:
Improveimplement positioning stabilityVSAvoidpressure control system
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The feedback control mechanism detects implement floatation and surface contour variations, then adjusts the hydraulic pressure differential to apply appropriate downward force. This closed-loop control stabilizes implement positioning and maintains guidance along surface contours while managing the complexity through intelligent pressure regulation.

Inventive Principle:
Principle #23Feedback

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

Enables uniform soil cultivation by adjusting contact pressure and preventing implement floatation, ensuring consistent performance in various agricultural tasks.

Implementation Method 1

a hydraulic cylinder with a working chamber which can be pressurised with hydraulic fluid to change the lifting position of a lower link

Methodology Applied
Scientific EffectHydraulic pressure: Pressure Increase

Implementation Method 2

By using a double-acting hydraulic cylinder and appropriately specifying the target pressure, it is possible to exert a downward force on the lower link

Methodology Applied
Scientific EffectHydraulic pressure: Pressure Increase

Data Source

PatentEP4344520B1Control arrangement for a hydraulic three-point power lift
Publication Date: 2025.07.02 DEERE & CO
  • EP4344520B1 patent drawingFigure 1
  • EP4344520B1 patent drawingFigure 2
  • EP4344520B1 patent drawingFigure 3

AI summary

Arrangement (10) for controlling a hydraulic three-point linkage (12), comprising a hydraulic cylinder (16) with a working chamber (18) which can be pressurized with hydraulic fluid to change the lifting position of a lower link encompassed by the hydraulic three-point linkage (12), and first and second poppet valves (24, 26) communicating with the working chamber (18), wherein the first poppet valve (24) is configured to establish an inlet connection (30) with a high-pressure source (22) and the second poppet valve (26) is configured to establish a return connection (32) with a hydraulic reservoir (28). This is a double-acting hydraulic cylinder (16) with a further working chamber (56) which is connected to a control valve arrangement (58) by means of which a predetermined target pressure can be set in the further working chamber (56).