Excavator Blade Float Control for Jacked-Up Body Stability
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Solution Overview
Problem
Construction machines, such as hydraulic excavators, face issues where the blade is inadvertently put into a floating state when the machine body is jacked up, leading to potential lowering of the machine body due to erroneous operator actions, and difficulty in performing leveling work when the blade is not properly lowered to follow ground undulations.
Innovation Solution
A construction machine equipped with a blade control system that includes a pressure sensor and a controller to validate or invalidate the floating command based on the pressure in the blade cylinder's oil chamber, preventing the blade from entering a floating state when the machine body is jacked up and ensuring proper leveling by allowing the blade to float when the machine body is not raised.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the blade control valve is switched to the floating position to enable leveling work, then the blade can follow ground undulations, but the machine body may be inadvertently lowered when jacked up for maintenance
Solution Approach 1:
The system changes the operational parameters of the blade control valve based on the detected state of the machine body. When the machine body is jacked up (detected by zero or near-zero hydraulic pressure in the blade cylinder), the control valve is restricted from switching to the floating position, preventing inadvertent lowering. When the machine body is on the ground (detected by non-zero hydraulic pressure), the floating position becomes available for leveling work.
Solution Approach 2:
The system uses a pressure sensor to continuously monitor the hydraulic pressure in the blade cylinder and provides feedback to the control unit. This feedback enables the control unit to determine whether the machine body is in a jacked-up state or on the ground, and accordingly enables or disables the floating position of the blade control valve to prevent erroneous operations.
2Reliability
If the blade control valve restricts floating position to prevent erroneous operation, then machine body stability is improved, but the blade cannot float when needed for leveling work
Solution Approach 1:
The system dynamically adjusts the functionality of the blade control valve based on real-time detection of the machine body state. The floating position is not permanently disabled but conditionally enabled or disabled based on whether the machine body is detected to be on the ground or jacked up, providing adaptive control that maintains both safety and functionality.
3Reliability
If the blade is always held in a fixed position to prevent lowering, then machine body stability is improved, but the blade cannot follow ground undulations for leveling work
Solution Approach 1:
The system changes the operational parameters of the blade control valve based on the detected state of the machine body. When the machine body is jacked up (detected by zero or near-zero hydraulic pressure in the blade cylinder), the control valve is restricted from switching to the floating position, preventing inadvertent lowering. When the machine body is on the ground (detected by non-zero hydraulic pressure), the floating position becomes available for leveling work.
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 the machine body from being lowered unintentionally when the blade control valve is operated in error during jacking operations and enables effective leveling by ensuring the blade can float and follow ground undulations when the machine body is not raised.
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
Data Source
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.