Fork Leveling Hydraulics Using Active-Passive Cylinder Oil Makeup

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Solution Overview

Problem

The existing fork leveling system for telescopic boom forklifts faces difficulties in automatic oil replenishment during automatic leveling, leading to inefficiencies, such as repeated tilting of the fork and oil leakage due to oil shortages in the leveling oil cylinder.

Innovation Solution

A fork leveling system incorporating an active leveling oil cylinder, a passive leveling oil cylinder, an electric control oil supplement valve, and a pressure reducing valve, which allows for automatic oil replenishment by connecting these components to ensure continuous oil supply without malfunctioning other valves, preventing empty suction and leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If automatic leveling function is implemented, then leveling efficiency is improved, but oil shortage problems occur leading to system failure

Engineering Contradiction:
Improveleveling efficiencyVSAvoidsystem reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system performs preliminary action by proactively monitoring oil levels and replenishing oil before the cylinder becomes empty. The controller detects oil level changes and activates the oil supplement valve to maintain adequate oil levels, preventing the harmful effect of empty suction and ensuring continuous reliable operation during automatic leveling cycles

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by using sensors to continuously monitor oil levels in the leveling oil cylinder and feeding this information back to the controller. The controller then adjusts the oil supplement valve accordingly, creating a closed-loop control system that maintains proper oil levels and prevents system failure while enabling continuous automatic leveling operation

Inventive Principle:
Principle #23Feedback

2Speed

If automatic leveling is performed without oil replenishment, then operation speed is improved, but fork tilting occurs reducing accuracy

Engineering Contradiction:
Improveoperation speedVSAvoidfork leveling precision
Core Design Contradiction:
SpeedVSManufacturing precision

Solution Approach 1:

The system ensures continuity of useful action by continuously monitoring oil levels and automatically replenishing oil during the automatic leveling process. This continuous oil supply maintenance allows the automatic leveling function to operate continuously without interruption or tilting errors, preserving both high speed operation and precise fork leveling accuracy

Inventive Principle:
Principle #20Continuity of useful action

3Quantity of substance

If oil supplement valve is added to leveling system, then oil replenishment capability is improved, but device complexity increases

Engineering Contradiction:
Improveoil supply capabilityVSAvoidsystem complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The system applies self-service by implementing an automatic oil supplementation mechanism where the controller autonomously monitors oil levels and activates the oil supplement valve as needed. This self-monitoring and self-replenishment capability ensures adequate oil supply without requiring manual intervention or complex external monitoring systems, achieving the balance between improved oil supply capability and acceptable system complexity

Inventive Principle:
Principle #25Self-service

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 effectively achieves automatic oil replenishment during automatic leveling, preventing failures and oil-related issues, ensuring efficient operation and maintaining the fork's level without manual intervention.

Implementation Method 1

an oil outlet of the electric control oil supplement valve is connected to an oil inlet of the pressure reducing valve; an oil outlet of the pressure reducing valve is connected to the rodless cavity of the active leveling oil cylinder and the rod cavity of the active leveling oil cylinder

Methodology Applied
Scientific EffectPressure reduction: Pressure Drop

Implementation Method 2

opening the electric control oil supplement valve when the fork in an initial position is horizontal to enable the oil pump to supply oil to the electric control oil supplement valve

Methodology Applied
Scientific EffectValve opening: Valve

Implementation Method 3

An oil inlet of the electric control oil supplement valve is connected to an oil pump

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP4053070B1Fork leveling system and method, and telescopic boom forklift
Publication Date: 2024.09.18 SANY MARINE HEAVY INDUSTRY CO LTD
  • EP4053070B1 patent drawingFigure 1
  • EP4053070B1 patent drawingFigure 2
  • EP4053070B1 patent drawingFigure 3

AI summary

The present disclosure provides a fork leveling system and method thereof, and a telescopic boom forklift, which relate to the technical field of hydraulic adjustment. The fork leveling system includes an active leveling oil cylinder (2), a passive leveling oil cylinder (4) and an electric control oil supplement valve (11), wherein a rodless cavity of the active leveling oil cylinder (2) is communicated with a rodless cavity of the passive leveling oil cylinder (4), and a rod cavity of the active leveling oil cylinder (2) is communicated with a rod cavity of the passive leveling oil cylinder (4); and an oil inlet of the electric control oil supplement valve (11) is connected to an oil pump (9), and an oil outlet of the electric control oil supplement valve (11) is connected to the rodless cavity of the active leveling oil cylinder (2) and the rod cavity of the active leveling oil cylinder (2). The telescopic boom forklift includes the fork leveling system, and the automatic leveling method for a fork is applicable to the fork leveling system. According to the fork leveling system and method thereof, and the telescopic boom forklift, the technical problem of difficulty in replenishing oil in a state of automatic leveling in the prior art can be solved to a certain degree.