Wheel Loader Oil Pressure System Reducing Boom Impact

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

The existing oil pressure systems for wheel loaders generate impact when the boom reaches maximum height during loading work due to abrupt halt in boom cylinder expansion, leading to potential product loss and stress on the machine.

Innovation Solution

An oil pressure system with a confluent circuit and oil pressure pumps set to different cutoff pressures, where one pump cuts off at approximately 90% of the maximum height, reducing the impact by gradually decreasing the boom's raising speed as it approaches maximum height.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the boom cylinder is expanded at maximum speed for work efficiency, then productivity is improved, but impact is generated when the boom approaches maximum height

Engineering Contradiction:
Improvework efficiencyVSAvoidimpact
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The oil pressure system is divided into two independent oil pressure pumps instead of using a single pump. Each pump can be independently controlled to have different cutoff pressures, allowing the system to segment the boom raising process into different speed phases - maximum speed for most of the行程 and reduced speed near the top position.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cutoff pressure parameter is set to different values for the two oil pressure pumps. One pump has a higher cutoff pressure to maintain maximum raising speed during most of the boom elevation, while the other pump has a lower cutoff pressure to reduce speed when the boom approaches maximum height, thereby reducing impact.

Inventive Principle:
Principle #35Parameter changes

2Object-generated harmful factors

If electronic control elements are added to track and control boom position, then impact can be reduced, but device complexity and manufacturing cost increase

Engineering Contradiction:
ImproveimpactVSAvoidmanufacturing complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The system uses the existing hydraulic components (two oil pressure pumps with different cutoff pressures) to automatically regulate the boom raising speed. The pumps self-adjust their operation based on their inherent cutoff pressure characteristics, eliminating the need for external electronic sensors, controllers, or position tracking systems.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention uses hydraulic pressure control mechanisms instead of electronic control. By setting different cutoff pressures in the two oil pressure pumps, the system hydraulically regulates the boom raising speed without requiring electronic constituents, thereby avoiding the complexity and cost associated with electronic control systems.

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Productivity

If the boom is raised to maximum height quickly, then productivity is improved, but stress is accumulated on machine components

Engineering Contradiction:
Improveraising speedVSAvoidstress on components
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The system dynamically adjusts the boom raising speed during the operation. By using two oil pressure pumps with different cutoff pressures, the boom is raised at maximum speed during most of the行程 and then automatically transitions to a reduced speed phase when approaching the maximum height, creating a dynamic speed profile that protects components from impact stress.

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

This solution effectively decreases the impact on the boom and bucket, reduces the risk of product loss, and minimizes stress on machine components without adding complex electronic elements, thus maintaining efficiency and reducing costs.

Implementation Method 1

a pair of oil pressure pumps configured to discharge hydraulic oil; a plurality of working devices including boom cylinders driven by a pressure of the hydraulic oil

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP2657538B1Oil pressure system for a wheel loader
Publication Date: 2020.02.05 DOOSAN INFRACORE CO LTD
  • EP2657538B1 patent drawingFigure 1~2
  • EP2657538B1 patent drawingFigure 3~4
  • EP2657538B1 patent drawing

AI summary

The present invention relates to an oil pressure system for a wheel loader, and more particularly to a wheel loader which includes an oil pressure system having a confluent circuit and reduces the occurrence of impact during a loading work, and to this end, the present invention provides the wheel loader which is composed of an oil pressure circuit characterized by setting different cutoff pressure values with respect to a pair of left and right oil pressure pumps connected through the confluent circuit, and according to the characteristic, it is possible to prevent loss of products loaded in a bucket due to an abrupt halt of a boom during the loading work and it is possible to considerably reduce an impulse of the wheel loader by operating the boom at a remarkably low speed in comparison with the maximum speed when the boom approaches the maximum height in a raising process of the boom during the loading work of the wheel loader.