Swing Motor Cavitation Prevention via Bypass Control Valve
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Solution Overview
Problem
In hydraulic systems, cavitation occurs in swing motors due to insufficient hydraulic oil supply when the joystick is not operated, leading to pressure drops and harsh noise, which can cause stress for operators.
Innovation Solution
A method involving a hydraulic system with a main pump, auxiliary pump, control valve unit, bypass cut valve, and control unit that controls the bypass control valve to maintain hydraulic oil supply to the swing motor by adjusting pressure and electric current values, ensuring sufficient oil is supplied even when the joystick is not operated, thereby preventing cavitation and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the joystick is not operated to stop the swing motor, then energy consumption is reduced, but hydraulic oil supply becomes insufficient causing cavitation
Solution Approach 1:
The bypass control valve is opened in advance before the swing motor actually stops, based on prediction of the stop state. This preliminary action ensures that the bypass passage is ready to supply hydraulic oil immediately when the motor stops, preventing cavitation without requiring continuous joystick operation
Solution Approach 2:
The control unit monitors the operational state of the swing motor and uses this feedback to control the bypass control valve. When the motor is predicted to stop (based on joystick position and motor state), the control unit opens the bypass valve to maintain hydraulic supply, creating a closed-loop control system that responds to actual system conditions
2Device complexity
If hydraulic oil supply is stopped when joystick is not operated, then system simplicity is maintained, but pressure decreases causing cavitation and noise
Solution Approach 1:
A bypass passage with a bypass control valve is introduced as an intermediary component. This bypass acts as a mediator that can selectively supply hydraulic oil to the swing motor when needed, without requiring complete system redesign or continuous main pump operation
Solution Approach 2:
Instead of maintaining hydraulic supply throughout the entire system, the bypass valve provides localized hydraulic oil supply only to the swing motor when predicted to stop. This local quality approach maintains system simplicity while preventing cavitation at the specific location where it occurs
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 method stabilizes hydraulic oil supply to the swing motor, preventing cavitation and associated noise, ensuring continuous operation and reducing operator stress by maintaining sufficient pressure in the system.
Implementation Method 1
an auxiliary pump which discharges pilot hydraulic oil; a control valve unit which is disposed on a hydraulic line connected to the main pump and is controlled to supply the hydraulic oil to the swing motor
Implementation Method 2
a bypass control valve which is controlled to connect the auxiliary pump and the bypass cut valve in an 'On' state, and to disconnect the auxiliary pump from the bypass cut valve in an 'Off' state
Implementation Method 3
a main pump which discharges hydraulic oil; a bypass cut valve which is disposed on the hydraulic line at a downstream side of the control valve unit
Implementation Method 4
a control unit which controls the bypass control valve, in which the bypass control valve is controlled such that after the bypass control valve is maintained in the 'On' state during a first delay time D1 from a point in time t1 where a first pressure Ps is formed in a pilot line
Data Source
AI summary
The present disclosure relates to a method for controlling a swing motor in a hydraulic system and a hydraulic system. The method for controlling the swing motor in the hydraulic system and the hydraulic system according to the exemplary embodiment of the present disclosure may ensure the sufficient amount of hydraulic oil in a make-up line in a situation in which the hydraulic oil needs to be supplementarily supplied to the swing motor in the hydraulic system. Therefore, it is possible to prevent the occurrence of cavitation in the swing motor by stably supplying the amount of hydraulic oil at the point in time where the hydraulic oil needs to be supplementarily supplied to the swing motor. In addition, it is possible to prevent the occurrence of abnormal noise which is harsh to the ear when the cavitation occurs.