Hydraulic Hunting Reduction Circuit for Excavator Turning Stability
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Solution Overview
Problem
Existing hydraulic turning mechanisms in operating machines like shovels experience a hunting phenomenon during deceleration, leading to vibrations in the turning body due to rapid fluctuations in hydraulic pressure when the operation lever returns to neutral, which existing solutions fail to adequately suppress.
Innovation Solution
A turning control apparatus is introduced, featuring a hunting reduction circuit that relieves hydraulic pressure at a deceleration-side hydraulic port before the operation lever returns to neutral, using a combination of high-pressure relief and makeup circuits to stabilize the deceleration process and prevent rapid pressure fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the operation lever returns to neutral position to stop turning, then the turning body stops, but rapid hydraulic pressure fluctuations cause hunting phenomenon and vibrations
Solution Approach 1:
The hunting reduction circuit opens before the operation lever returns to neutral position, performing preliminary pressure relief action to prevent the hunting phenomenon before it occurs. This anticipatory action stabilizes the hydraulic pressure during the deceleration phase, eliminating vibrations in the turning body.
Solution Approach 2:
The hunting reduction circuit acts as an intermediary element between the main hydraulic circuit and the turning hydraulic motor. It mediates the pressure fluctuations by providing a controlled relief path, preventing direct transmission of pressure shocks to the turning mechanism and thereby reducing hunting phenomenon.
2Productivity
If hydraulic pressure is supplied to drive the turning hydraulic motor, then the turning mechanism operates, but pressure fluctuations occur during deceleration
Solution Approach 1:
The hunting reduction circuit is controlled by a sensor that detects the position of the operation lever and the state of the turning hydraulic motor. This feedback control system opens the hunting reduction circuit at the appropriate moment during deceleration, maintaining stable hydraulic pressure while preserving turning operation efficiency.
Solution Approach 2:
The hunting reduction circuit dynamically adjusts the hydraulic pressure relief based on the operating conditions. It remains closed during normal operation to maintain pressure efficiency, and opens selectively during deceleration to stabilize pressure, thereby maintaining both productivity and pressure stability.
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 solution effectively suppresses the hunting phenomenon and associated vibrations in the turning body during deceleration, ensuring smoother operation and reduced mechanical stress by maintaining controlled hydraulic pressure levels.
Implementation Method 1
a high-pressure relief circuit that relieves a hydraulic pressure of a first hydraulic line at a first relief pressure, the first hydraulic line supplying an operating oil to drive the hydraulic motor
Implementation Method 2
a hunting reduction circuit that relieves a hydraulic pressure of a second hydraulic line at a pressure lower than the first relief pressure, the second hydraulic line being connected to a deceleration-side hydraulic port
Data Source
AI summary
A turning control apparatus includes a turning body and a hydraulic motor to turn the turning body. A high-pressure relief circuit relieves hydraulic pressure of a first hydraulic line at a first relief pressure, the first hydraulic line supplying an operating oil to drive the hydraulic motor. A hunting reduction circuit relieves a hydraulic pressure of a second hydraulic line at a pressure lower than the first relief pressure, the second hydraulic line being connected to a deceleration-side hydraulic port from which the operating oil is discharged when the hydraulic motor is being driven. The hunting reduction circuit connected to the deceleration-side hydraulic port is caused to open before an operation lever to operate turning of the turning body returns to a neutral position.