Arm Control Valve Return Pressure Compensation for Excavator Crowd Speed
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Solution Overview
Problem
Existing control systems for construction machinery, particularly excavators, face difficulties in tuning the area diagram of the arm control spool during arm crowd operations and incur high processing costs due to the application of regenerative cut valves.
Innovation Solution
A control system that includes a pressure compensated valve in the return hydraulic line of the arm control valve, which controls the flow rate of working oil based on pressure differences between the front and rear ends of the valve, using pilot pressures from the rod and return hydraulic lines, and a compensation spring to adjust the opening amount, allowing for efficient speed control and reduced pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a regenerative cut valve is applied to the arm control valve, then regeneration of hydraulic oil is achieved, but tuning of the area diagram becomes very difficult and processing costs increase
Solution Approach 1:
The invention extracts the pressure compensation function from the complex regenerative cut valve and implements it as a separate, simple pressure compensated valve in the return hydraulic line. This valve only needs to sense pressure difference between front and rear ends of the control valve, eliminating the need for complex area diagram tuning while achieving the same energy regeneration effect.
Solution Approach 2:
The pressure compensated valve acts as an intermediary device that mediates the pressure difference between the front end and rear end of the control valve. By using pilot pressures from both sides of the control valve, it automatically adjusts the return flow without requiring complex tuning parameters, thus simplifying the overall system control.
2Loss of energy
If a regenerative cut valve is applied to the arm control valve, then hydraulic oil regeneration is achieved, but processing costs for applying the valve are high
Solution Approach 1:
The invention replaces the expensive regenerative cut valve with a simpler, cheaper pressure compensated valve that can be easily manufactured and installed. The pressure compensated valve uses basic hydraulic components (pilot lines, spring, spool) that are standard in the industry, significantly reducing processing costs while maintaining the energy regeneration function.
3Device complexity
If traditional control valve is used, then structure is simple, but speed control during arm crowd operation is difficult
Solution Approach 1:
The pressure compensated valve implements automatic feedback control by sensing the pressure difference between the front end and rear end of the control valve through pilot lines. This feedback mechanism automatically adjusts the return flow rate to maintain optimal speed control during arm crowd operations, eliminating the need for complex manual tuning or additional control mechanisms.
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
The system facilitates easy tuning and reduces pressure loss and back pressure, saving energy and eliminating the need for frequent adjustments during arm crowd operations, even with changes in bucket weight, thus achieving desired control performance at a lower cost.
Implementation Method 1
the pressure compensated valve being configured to control a flow rate of the working oil passing through the pressure compensated valve according to a pressure difference between a front end and a rear end of the control valve
Implementation Method 2
the pressure compensated valve may include a compensation spring that is connected to a compensation spool and is configured to compensate the pressure difference between the front end and the rear end of the control valve by a spring force
Data Source
AI summary
A control system for construction machinery includes a hydraulic cylinder operable by a working oil discharged from a hydraulic pump, a control valve arranged between the hydraulic pump and the hydraulic cylinder to control an operation of the hydraulic cylinder according to a position of a spool therein, the control valve having a first spool position for draining the working oil discharged from a chamber of the hydraulic cylinder to a drain tank, and a pressure compensated valve installed in a return hydraulic line through which the working oil discharged from the control valve at the first spool position is drained to the drain tank, the pressure compensated valve being configured to control a flow rate of the working oil passing through the pressure compensated valve according to a pressure difference between a front end and a rear end of the control valve.