Hydraulic Auto-Levelling Circuit With Flow Dividers for Tool Alignment

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Solution Overview

Problem

Existing hydraulic systems for maintaining tool orientation in machines like telehandlers and front-end loaders face challenges in accuracy and alignment during hoisting and lowering, especially with varying load weights and flow rates, and are either cumbersome or difficult to implement in smaller machines.

Innovation Solution

A hydraulic system with adjustable flow dividers that maintain a constant outlet flow ratio independently of the inlet flow rate, ensuring precise control of the hoisting and aligning cylinder-piston groups to maintain tool orientation, using proportional valves and compensators to adjust fluid pressure and flow rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a hydraulic system with master and slave cylinders is used to maintain tool orientation, then the orientation control is achieved, but the system becomes difficult to implement in medium/small sized machines

Engineering Contradiction:
Improvetool orientation controlVSAvoidsystem implementation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The hydraulic system is segmented into two independent flow dividers (first and second flow dividers) that operate in parallel. Each flow divider independently manages flow distribution to the hoisting cylinder and aligning cylinder, eliminating the need for complex master-slave cylinder interactions while maintaining orientation control reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Flow dividers are introduced as intermediary hydraulic components that automatically distribute fluid flow between the hoisting and aligning cylinders based on predefined ratios. These intermediaries simplify the control architecture by replacing complex control logic with passive flow distribution mechanisms.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a mechanical four-bar linkage system is used to maintain tool orientation, then the orientation is maintained, but the machine weight increases and field of view is impaired

Engineering Contradiction:
Improvetool orientation maintenanceVSAvoidmachine weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The mechanical four-bar linkage system is replaced with a hydraulic control system using flow dividers and cylinder-piston groups. This substitution eliminates bulky mechanical linkages and their associated weight, while maintaining the same orientation maintenance function through fluid-powered actuation.

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

Solution Approach 2:

The patent employs hydraulic actuators (cylinder-piston groups) controlled by flow dividers to maintain tool orientation. This hydraulic approach replaces heavy mechanical linkages with lighter fluid-powered systems, reducing overall machine weight while preserving the orientation control capability.

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Reliability

If electronic control with sensors is used to maintain tool inclination, then the inclination control is achieved, but the system complexity and cost increase

Engineering Contradiction:
Improveinclination controlVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The hydraulic flow dividers are designed to automatically maintain the correct flow ratio between hoisting and aligning cylinders without requiring external sensing or electronic control. The system serves itself through inherent hydraulic principles, eliminating the need for sensors, controllers, and complex electronic circuitry.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system uses adjustable flow dividers that allow operators to modify flow distribution parameters directly at the hydraulic components. This simple parameter adjustment mechanism replaces complex electronic control systems while maintaining inclination control reliability.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If sophisticated hydraulic circuits are used to hold desired tool inclination, then the inclination control is achieved, but accurate control and alignment become difficult to maintain during hoisting and lowering

Engineering Contradiction:
Improvetool inclination controlVSAvoidalignment accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The flow dividers are pre-configured with adjustable elements that set the correct flow ratio before operation begins. This preliminary configuration ensures that the aligning cylinder receives the proper amount of fluid to maintain orientation throughout the entire range of motion, preventing alignment errors during hoisting and lowering operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses dynamically adjustable flow dividers that can adapt to different operating conditions. The adjusting elements allow the flow distribution ratio to be optimized for specific load conditions and operational requirements, maintaining alignment accuracy across varying hoisting and lowering scenarios.

Inventive Principle:
Principle #15Dynamics

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 system ensures accurate and consistent tool alignment and orientation during both hoisting and lowering operations, regardless of the load weight or flow rate, improving operational efficiency and reducing system complexity.

Implementation Method 1

a first flow divider (10) configured to separate an inlet fluid flow into two outlet flows, both having a constant flow rate, which depends on adjusting elements (17, 19) independently from the inlet flow rate; and a second flow divider (11) configured to separate an inlet fluid flow into two outlet flows, both having a constant flow rate, which depends on adjusting elements (26, 28) independently from the inlet flow rate

Methodology Applied
Scientific EffectFluid flow division:

Implementation Method 2

The system comprises a first and second actuator groups, such as a hoisting cylinder-piston group (4) and an aligning cylinder-piston group (5)

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP3742001B1Hydraulic system hoisting and auto-levelling a tool
Publication Date: 2023.01.25 HYDAC SPA
  • EP3742001B1 patent drawingFigure 1
  • EP3742001B1 patent drawingFigure 2

AI summary

Hydraulic system (1) for hoisting and auto-levelling a tool connected to a hoisting arm, comprising: - a first supplying and unloading port/connection (2) and a second supplying and unloading port/connection (3) directly or indirectly connected or connectable to a storage reservoir and a pump for pressurizing a working fluid; - a hoisting actuator group (4) connected or connectable by said hoisting arm to the tool for hoisting/lowering it, and having a first port/connection (6) for gaining access to a first chamber thereof, and a second first port/connection (7) for gaining access to a second chamber thereof; - an aligning actuator group (5) connected or connectable to the tool and hoisting arm for holding the tool according to an orientation predefined during said hoisting/lowering steps and having a first port/connection (8) for gaining access to a first chamber thereof and a second port/connection (9) for gaining access to a second chamber thereof; - a first flow divider (10) comprising an inlet (12), a first outlet (13) and a second outlet (14), configured to separate a flow rate entering the inlet (12) in a first and second predefined flow rates exiting the first (13) and second outlets (14), respectively; - a second flow divider (11) comprising an inlet (21), a first outlet (22) and a second outlet (23), configured to separate a flow rate entering the inlet (21) in a first and second predefined flow rates exiting the first (22) and second outlets (23), respectively, wherein: - the inlet (12) of the first flow divider (10) is fluidically connected to the second port/connection (7) of the hoisting actuator group (4); - the first outlet (13) of the first flow divider (10) is fluidically connected to the second supplying and unloading port/connection (3); - the second outlet (14) of the first flow divider (10) is fluidically connected to the first port/connection (8) of the first aligning actuator (5); - the inlet (21) of the second flow divider (11) is fluidically connected to the first port/connection (6) of the hoisting actuator group (4); - the first outlet (22) of the second flow divider (11) is fluidically connected to the first supplying and unloading port/connection (2); - the second outlet (23) of the second flow divider (11) is fluidically connected to the second port/connection (9) of the aligning actuator group (5).