Excavator Blade Float Control for Safe Jacking and Leveling
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Solution Overview
Problem
Construction machines, such as hydraulic excavators, face issues where the blade can inadvertently enter a floating state when the machine body is jacked up, leading to unintended lowering, and struggle with effective leveling due to improper blade control valve configurations.
Innovation Solution
A construction machine equipped with a blade control valve system that includes a pressure sensor and controller to validate or invalidate floating and lowering commands based on the machine body's state, preventing the blade from floating when jacked up and ensuring proper leveling by allowing floating when not jacked up, using a hydraulic fluid management system with specific valve positions and lever operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the blade control valve is configured with a floating position to enable leveling work, then the blade can follow ground undulations effectively, but the machine body may be inadvertently lowered when the blade is used for jacking up the machine body
Solution Approach 1:
The system uses a pressure sensor to detect the pressure in the bottom-side oil chamber of the blade cylinder and feeds this information back to the controller. The controller determines whether the blade is in a jacking state based on the detected pressure and accordingly controls the blade control valve to prevent unintended floating, thus resolving the contradiction between leveling capability and position stability
Solution Approach 2:
The system dynamically changes the control mode of the blade control valve based on the working state. When the blade is used for jacking (high pressure detected), the floating position is disabled. When the blade is used for leveling (normal pressure detected), the floating position is enabled. This dynamic adaptation resolves the contradiction by making the system behavior context-dependent
2Productivity
If the blade control valve switches to floating position to allow blade to follow ground shape, then leveling work can be performed, but erroneous operation may cause machine body to lower
Solution Approach 1:
The pressure sensor continuously monitors the hydraulic pressure and provides feedback to the controller. When jacking pressure is detected, the controller prevents the blade control valve from switching to the floating position, thereby eliminating the harmful effect of unintended machine body lowering while preserving leveling efficiency during normal operations
Solution Approach 2:
The controller acts as an intermediary between the blade operation device and the blade control valve. It intermediates the control signal by validating or invalidating the floating command based on pressure feedback, thus preventing erroneous operations from causing harmful effects while allowing legitimate leveling operations to proceed
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
Prevents machine body lowering during erroneous operations when jacked up and enables effective leveling by ensuring the blade enters a floating state only when the machine body is not raised, enhancing operational safety and efficiency.
Implementation Method 1
a pressure sensor that detects a pressure in a bottom-side oil chamber of the blade cylinder
Implementation Method 2
a blade cylinder that is operated by hydraulic fluid delivered from a hydraulic pump and that drives the blade in the vertical direction
Implementation Method 3
hydraulic fluid from the hydraulic pump is supplied into the rod-side oil chamber of the blade cylinder to contract the blade cylinder, thereby raising the blade
Data Source
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AI summary
Provided is a construction machine that can prevent a machine body from being lowered without placing a blade in a floating state when the machine body is jacked up, even if the operator performs an erroneous operation, and that can perform favorable leveling work by placing the blade in the floating state when the machine body is not jacked up. A hydraulic excavator includes a pressure sensor that detects the pressure in a bottom-side oil chamber of a blade cylinder, and a controller that switches between validation and invalidation of a floating command and a lowering command for a blade operation device. In the case where the pressure detected by the pressure sensor is less than a predetermined value, the controller switches a solenoid selector valve to an interruption position to invalidate the floating command when a forward stroke of the operation lever is equal to or more than a reference value. In the case where the pressure detected by the pressure sensor is equal to or more than the predetermined value, the controller holds the solenoid selector valve in a communication position to validate the floating command when the forward stroke of the operation lever is equal to or more than the reference value.