Hydraulic Travel Force Equalization for Straight-Running Machines

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Solution Overview

Problem

Existing working machines do not adequately address straight-driveability during intermediate operation, where the control devices are operated between neutral and maximum positions, leading to suboptimal traveling performance.

Innovation Solution

A working machine equipped with a hydraulic pump system that includes a correction mechanism to equalize the driving forces of the first and second traveling hydraulic actuators when both operation devices are operated at the same extent, improving straight-traveling performance by connecting the first and second output tubes via a communication tube and utilizing a traveling independent valve to manage fluid flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the right and left control devices are operated simultaneously at the same operation amount, then the working machine travels straight ahead, but the straight-driveability is not adequately improved during intermediate operation

Engineering Contradiction:
Improvestraight-driveabilityVSAvoidintermediate operation performance
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The invention changes the pressure parameter by introducing a correction mechanism that equalizes the pressure between the right and left hydraulic actuators during intermediate operation. This pressure equalization ensures that both traveling devices receive equal driving force, improving straight-driveability without requiring full-stroke operation of the control devices.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention introduces a pressure equalization mechanism as an intermediary between the right and left hydraulic actuators. This mechanism includes a communication channel that allows pressure equalization, ensuring that both sides receive equal driving force during intermediate operation, thereby improving straight-driveability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the traveling bypass valve is switched to equalize driving forces, then straight-driveability improves, but the device complexity increases

Engineering Contradiction:
Improvestraight-driveabilityVSAvoidvalve mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the correction mechanism with the existing traveling independent valve assembly. The communication channel for pressure equalization is integrated into the valve body structure, and the correction mechanism shares components with the bypass mechanism, thereby reducing overall device complexity while maintaining straight-driveability improvement.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The traveling independent valve assembly is designed to perform multiple functions: it serves as both the bypass valve for equalizing driving forces and as part of the correction mechanism for pressure equalization. This multi-functionality reduces the need for separate dedicated components, thereby reducing device complexity.

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

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

Enhances traveling straightness during intermediate operations by ensuring equal driving forces to the traveling devices, thereby improving overall traveling performance and straight-driveability.

Implementation Method 1

a hydraulic pump (first hydraulic pump) that supplies pressurized fluid

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 2

connecting the first and second output tubes via a communication tube

Methodology Applied
Scientific EffectFluid flow:

Data Source

PatentEP3524825B1Working machine
Publication Date: 2022.05.11 KUBOTA CORP
  • EP3524825B1 patent drawingFigure 1
  • EP3524825B1 patent drawingFigure 2
  • EP3524825B1 patent drawingFigure 3

AI summary

A working machine (1) includes a hydraulic pump (18, 19), a first traveling device (3R) configured to be driven by a first traveling hydraulic actuator (MR), a second traveling device (3L) configured to be driven by a second traveling hydraulic actuator (ML), a first output tube (41) configured to connect a first output port (P1) of the hydraulic pump (18, 19) to the first traveling hydraulic actuator (MR), a second output tube (42) configured to connect a second output port (P2) of the hydraulic pump (18, 19) to the second traveling hydraulic actuator (ML), a first operation device (44R) configured to operate the first traveling device (3R), a second operation device (44L) configured to operate the second traveling device (3L), and a correction mechanism (60A, 60B, 60C) configured to equalize a driving force of the first traveling hydraulic actuator (MR) and another driving force of the second traveling hydraulic actuator (ML) when the first operation device (44R) and the second operation device (44L) are operated each at same operation extents to perform a straight-traveling operation.