新聞摘要:Excavator hydraulic system, for some reason, the pressure of the liquid suddenly suddenly rise at a moment, forming a pressure peak, this phenomenon is called hydraulic impact. The peak pressure of hydraulic impact can be as high as 2~4 times of normal wo
Excavator hydraulic system, for some reason, the pressure of the liquid suddenly suddenly rise at a moment, forming a pressure peak, this phenomenon is called hydraulic impact. The peak pressure of hydraulic impact can be as high as 2~4 times of normal working pressure, which will cause great harm to the system, and hydraulic shock must be minimized.
(1) there are 5 reasons for the hydraulic shock produced. If the valve is energized, the valve suddenly closed, hydraulic shock in the pipeline will directly impact (the impact) and indirect impact (non impact) are likely to make the impact pressure tube reaches maximum; moving parts in high-speed motion and stop suddenly, for example, the hydraulic cylinder piston suddenly stop or reverse the stroke middle or end of the cylinder, and the main valve too fast, will produce hydraulic impact; in the transition zone between the hydraulic pump, hydraulic oil, or in too many bends, the bending angle of the pipeline is too small, it is easy to produce hydraulic shock; hydraulic system components of some action is not sensitive enough (such as overflow valve unresponsive) that will produce hydraulic shock.
(2) the harm caused by the impact of the hydraulic component in hydraulic systems, piping and instrument damage; pressure relay will false signal interference, normal operation of the hydraulic system, affecting its working stability and reliability; caused by vibration and noise, loose connections, causing leakage, pressure regulating valve pressure causes the system to change; high temperature, accelerated aging failure, seal leakage.
(3) prevention methods
Slow down the reversing speed of the reversing valve, that is to say, to prolong the commutation time. For example, the DC electromagnetic valve than hydraulic AC electromagnetic valve impact to small; using the electro-hydraulic valve with damping, damping by adjusting the size and control of pressure and flow through the pilot valve, main valve spool slow reversing speed (opening and closing).
The increase of diameter, the velocity decreases, thereby reducing the change of flow rate value, reducing the buffer pressure; shorten the length, to avoid unnecessary bends; the rubber hose can obtain good effect.
Slow the flow of liquid before the spool closes completely. Such as improving the structure of the control valve side (rectangular or V shaped slot on the edge of the valve core or making a cone-shaped throttling cone), the design of the valve port can be properly designed, and the hydraulic impact can be greatly reduced.
A deceleration valve is used at the end of the hydraulic cylinder to reduce the hydraulic impact due to the slow closing of the oil circuit.
A buffer device (such as a one-way throttle valve) is arranged at the end of the hydraulic cylinder to control the speed of the oil discharge at the end of the hydraulic cylinder, so that the piston can move smoothly and no impact when the cylinder end stops.
Set the balance valve and back pressure valve in the hydraulic cylinder oil return control circuit, to control the rapid decline or horizontal movement before the impact, and appropriate high back pressure.
When the pipeline is easy to produce hydraulic impact on the setting of the accumulator to absorb shock pressure.