Excavator Arm Control via Pressure Feedback
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Solution Overview
Problem
Existing work vehicle control systems face challenges in accurately controlling work implements due to variations in pilot pressure, leading to inappropriate operation of boom and arm movements, especially when the operation lever's tilt increases the speed of the work implement, causing the cutting edge to move above the designed surface.
Innovation Solution
A work vehicle configuration that includes a switching valve, operation member, pilot pressure control valve, electromagnetic proportional valve, upstream pilot flow path, and pressure sensor, where the control section selects and sets the current value for the electromagnetic proportional valve based on detected pressure, ensuring equal input and output pressures, thereby matching estimated and actual operation speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the electromagnetic proportional valve is controlled based on pilot pressure from the pilot pressure control valve, then automatic control of the work implement is enabled, but the work implement cannot be appropriately controlled when pilot pressure changes due to operation lever operation
Solution Approach 1:
The patent introduces a feedback mechanism where a pressure sensor detects the actual pilot pressure and feeds this information back to the control section. The control section then adjusts the electromagnetic proportional valve's current based on the detected pressure to maintain accurate control of the work implement, resolving the contradiction between automation and control reliability.
Solution Approach 2:
The patent replaces the purely mechanical pressure control system with an electro-hydraulic control system. The electromagnetic proportional valve uses electrical current control based on pressure sensor feedback to regulate hydraulic pressure, substituting mechanical linkages with electronic sensing and control to achieve both automation and reliability.
2Productivity
If the operation lever tilt increases to speed up work implement operation, then productivity increases, but the cutting edge moves above the designed surface causing loss of precision
Solution Approach 1:
The patent implements dynamic pressure control where the control section continuously adjusts the electromagnetic proportional valve based on real-time pressure sensor feedback. This dynamic adjustment allows the system to maintain precise control of the cutting edge position even when operation speed varies, enabling both high productivity and manufacturing precision.
Solution Approach 2:
The patent changes the control parameter from fixed mechanical linkage to variable electrical current based on pressure feedback. By adjusting the current to the electromagnetic proportional valve according to detected pressure and required operation speed, the system maintains accurate cutting edge positioning across different productivity levels.
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 configuration allows for precise control of the work implement, preventing the cutting edge from moving above the designed surface by ensuring the operation speed matches the estimated speed, thus maintaining accurate control during operations like leveling terrain.
Implementation Method 1
a pressure sensor configured to detect pressure of the second hydraulic fluid inside the upstream pilot flow path
Implementation Method 2
an electromagnetic proportional valve installed between the switching valve and the pilot pressure control valve
Data Source
AI summary
A hydraulic excavator is provided with an arm cylinder, an arm switching valve, a sixth pilot pressure control valve, a sixth electromagnetic proportional valve, a sixth upstream pilot flow path, a sixth hydraulic pressure sensor, and a control section. The control section selects at least one item of current value information from a plurality of items of current value information on the basis of a hydraulic pressure that is detected by the sixth hydraulic pressure sensor. The control section is configured to set a current value of a current that is output to the sixth electromagnetic proportional valve on the basis of the current value information that is selected.