Backflow Prevention Circuit Control for Free Blade Float Movement

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Solution Overview

Problem

In working machines with a backflow prevention circuit, the blade cannot be lifted when the directional switching valve is at the float position, making it difficult to freely move the blade up and down.

Innovation Solution

A method for controlling a working machine that controls the supply of a working fluid to an actuator by a pilot signal, allowing bidirectional movement of the driven object between two positions. The method includes a backflow prevention circuit that is disabled by the pilot signal during specific operations, enabling the working fluid to flow in the direction to move the driven object from the second position to the first position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a backflow prevention circuit is provided to prevent the machine body from falling, then the machine body stability is improved, but the blade cannot be lifted when the directional switching valve is at the float position

Engineering Contradiction:
Improvemachine body stabilityVSAvoidblade movement freedom
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention makes the backflow prevention circuit dynamically switchable between enabled and disabled states based on operational needs. The control valve responds to operation signals to selectively activate or deactivate the backflow prevention function, allowing the system to adapt between stable jack-up mode and free float mode for blade leveling work.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the flow resistance parameter of the backflow prevention circuit from high (when enabled) to low or zero (when disabled). By controlling the opening degree of the control valve, the system adjusts the backflow prevention capability to match different operational requirements, enabling both stable support and free movement functions.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If the directional switching valve is set to float position for free blade movement, then the blade can move up and down freely, but the backflow prevention circuit blocks the working fluid flow

Engineering Contradiction:
Improveblade movement freedomVSAvoidcontrol system complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The invention merges the float position control and backflow prevention control into a single integrated control mechanism. The control valve simultaneously manages both the directional switching and backflow prevention functions, eliminating the need for separate control systems while achieving both free blade movement and stable support capabilities.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The control valve is designed with multi-functionality, serving both as a directional switching device and a backflow prevention controller. By responding to different operation signals, the same valve component achieves multiple functions including float mode activation and backflow prevention, reducing overall system complexity.

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

3Reliability

If the backflow prevention circuit is always enabled to prevent machine body from falling, then the machine body stability is improved, but the blade cannot be freely moved up and down

Engineering Contradiction:
Improvemachine body stabilityVSAvoidblade movement freedom
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The invention dynamically adjusts the backflow prevention circuit state based on real-time operational signals. During jack-up operations, the circuit remains enabled for stability; during float operations for leveling, the circuit is disabled to allow free blade movement. This dynamic adaptation resolves the contradiction between stability and movement freedom.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control system preemptively disables the backflow prevention circuit before float operations begin, preventing the circuit from blocking necessary fluid flow. By anticipating the operational mode change, the system prepares the hydraulic circuit in advance to enable free blade movement when needed.

Inventive Principle:
Principle #9Preliminary anti-action

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 allows the working machine to be easily made multifunctional, enabling the blade to be freely moved up and down, even when the backflow prevention circuit is engaged.

Implementation Method 1

controls the supply of a working fluid to an actuator that drives a driven object by a pilot signal of an operation system

Methodology Applied
Scientific EffectHydraulic control: Hydraulic Press

Implementation Method 2

preventing a flow of the working fluid in a direction to move the driven object from the second position to the first position using a backflow prevention circuit

Methodology Applied
Scientific EffectBackflow prevention: Valve

Data Source

PatentEP4549669A1Method for controlling working machine and working machine
Publication Date: 2025.05.07 YANMAR HLDG CO LTD
  • EP4549669A1 patent drawingFigure 1
  • EP4549669A1 patent drawingFigure 2
  • EP4549669A1 patent drawingFigure 3

AI summary

[Problem] To provide a method for controlling a working machine and a working machine that can be easily made multifunctional. [Solution] The method for controlling a working machine 3 controls the supply of a working fluid to an actuator that drives a driven object by a pilot signal Si0 of an operation system generated according to the operation of an operation device 2, thereby moving the driven object bidirectionally between a first position and a second position. The method for controlling the working machine 3 includes preventing a flow of the working fluid in the direction to move the driven object from the second position to the first position by a backflow prevention circuit 7. The method for controlling the working machine 3 is characterized by further including disabling the backflow prevention circuit 7 by the pilot signal Si0 generated during a specific operation, thereby allowing the flow of the working fluid in the direction to move the driven object from the second position to the first position.