Atos ATOS relief valve fault causes and troubleshooting methods

Atos ATOS relief valve failure causes and troubleshooting
ATOS relief valve noise and vibration
The components of the ATOS relief valve hydraulic device that are prone to noise are generally considered to be pumps and valves, and the valve is mainly composed of a relief valve and an electromagnetic reversing valve. There are many factors that generate noise. The noise of the relief valve is two types of flow sound and mechanical sound. Noise in the flow sound is mainly caused by oil vibration, holes and hydraulic shock. The noise generated by mechanical shock is mainly caused by the impact and friction of parts in the valve.
(1) Noise caused by uneven pressure of ATOS relief valve
The pilot valve portion of the ATOS pilot type relief valve is a vibration-prone part as shown in Figure 3. When overflowing under high pressure conditions, the axial opening of the pilot valve is small, only 0.003 to 0.006 cm. The flow area is small, the flow rate is very high, up to 200 m / s, which is easy to cause uneven pressure distribution, causing the radial force of the cone valve to be unbalanced and generate vibration. In addition, the ovality generated during the processing of the cone valve and the cone valve seat, the dirt of the pilot valve port and the deformation of the pressure regulating spring may also cause the vibration of the poppet valve. Therefore, the pilot valve is generally considered to be the source of the vibration source.
Due to the presence of elastic elements (springs) and moving mass (cone valve), the ATOS relief valve constitutes a condition for oscillation, and the front chamber of the pilot valve acts as a resonant cavity, so the cone valve is easy to vibrate. It causes resonance of the entire valve to generate noise, and when noise occurs, it is often accompanied by severe pressure jump.
(2) Noise generated by the hole in the ATOS overflow valve
ATOS overflow valve When air is drawn into the oil for various reasons, or when the oil pressure is lower than atmospheric pressure, part of the air dissolved in the oil will precipitate to form bubbles, which are bulky in the low pressure zone. When the oil flows to the high pressure zone, it is compressed, the volume suddenly becomes smaller or the bubble disappears; conversely, if it is in the high pressure zone, the volume is originally small, and when it flows to the low pressure zone, the volume suddenly increases, and the bubble in the oil This rapid change in volume. A sudden change in bubble volume produces noise, and as this process occurs in an instant, it will cause local hydraulic shock and vibration. The pilot valve and the main valve port of the pilot type relief valve vary greatly in oil flow rate and pressure, and cavitation is prone to occur, thereby generating noise and vibration.
(3) Noise generated by hydraulic shock of ATOS relief valve
When the ATOS pilot operated relief valve is unloaded, pressure shock noise will occur due to a sudden drop in the pressure of the hydraulic circuit. The higher the pressure and the larger the working condition, the larger the impact noise is. This is because the relief time of the relief valve is short and the hydraulic shock is caused. When the unloading occurs, the sudden change of the oil flow rate causes a sudden change in pressure. The impact of pressure waves. The pressure wave is a small shock wave, and the noise generated by itself is very small, but as the oil is transferred to the system, if it resonates with any mechanical part, it may increase vibration and enhance noise. Therefore, when hydraulic shock noise occurs, system vibration is generally accompanied.
(4) ATOS relief valve mechanical noise
The mechanical noise emitted by the ATOS pilot-operated relief valve typically comes from the impact of the part and the friction of the part due to machining errors.
Among the noise emitted by the pilot type relief valve, there is sometimes a mechanical high-frequency vibration sound, which is generally called self-excited vibration sound. This is the sound of the main valve and pilot valve due to high frequency vibration. Its incidence is related to the configuration of the return line, flow, pressure, oil temperature (viscosity) and other factors. Under normal circumstances, the pipe diameter is small, the flow rate is low, the pressure is high, the viscosity of the oil is low, and the incidence of self-excited vibration is high.
ATOS relief valve other failure
ATOS relief valves may cause undue external leakage during assembly or use due to damage to O-rings, combination seals, or loose mounting screws or fittings.
If the cone valve or the main spool is worn too much, or the sealing surface is not well contacted, it will cause excessive internal leakage and even affect normal operation.
Common faults of the ATOS electromagnetic spill valve include the failure of the first conductive magnetic valve, the failure of the main valve, and the impact noise during unloading. The latter can be reduced or eliminated by adjusting the added buffer. If there is no buffer, a back pressure valve can be added to the main valve overflow. (The pressure is generally adjusted to about 5kgf/cm2, which is 0.5MPa).
ATOS relief valve works
ATOS relief valve is a hydraulic pressure control valve. In the hydraulic equipment, it mainly plays the role of constant pressure overflow, voltage regulation, system unloading and safety protection.
V constant pressure overflow: In the fixed pump throttle regulation system, the fixed pump provides a constant flow. When the system pressure increases, the flow demand is reduced. At this point, the relief valve opens, allowing excess flow to overflow back to the tank, ensuring the inlet pressure of the relief valve, ie the pump outlet pressure is constant (the valve port often opens with pressure fluctuations).
ATOS relief valve regulator: The relief valve is connected in series on the return line, the relief valve produces back pressure, and the smoothness of moving parts increases.
ATOS relief valve system unloading function: a small flow solenoid valve is connected in series at the remote control port of the relief valve. When the electromagnet is energized, the remote control port of the relief valve passes through the fuel tank, and the hydraulic pump is unloaded. The relief valve is now used as an unloading valve.
ATOS relief valve safety protection: When the system is working normally, the valve is closed. Only when the load exceeds the specified limit (system pressure exceeds the set pressure), the overflow is turned on, and the overload protection is performed, so that the system pressure is no longer increased (usually the set pressure of the relief valve is 10% to 20% higher than the maximum working pressure of the system). ).
ATOS relief valve is generally used in the application of unloading valve, as a remote pressure regulating valve, as a high and low pressure multi-stage control valve, as a sequence valve, used to generate back pressure (string on the return line).
ATOS relief valves generally have two configurations: 1. Direct-acting relief valve. 2. Pilot operated relief valve.
The main requirements of the ATOS relief valve are: large pressure regulation range, small pressure regulation deviation, small pressure oscillation, sensitive action, large overload capacity and low noise.