Aluminum die casting regulating valve parts

The overflow valve is a hydraulic pressure control valve in hydraulic equipment mainly from the overflow effect of constant pressure, voltage, unloading and safety protection system

main function

Overflow effect of constant pressure: the quantitative pump throttle system, the quantitative constant flow pump is provided. When the system pressure increases, will reduce traffic demand. When the relief valve opens, the excess flow back to the tank overflow to ensure the relief valve inlet pressure, the pump outlet pressure constant (often with the pressure fluctuations valve port open).

Stabilizing function: relief valve series in the oil line relief valve back pressure generated, moving parts more stable.

Unloading function: connect overflow solenoid valve small flow on the remote control port overflow valve, when the electromagnet power, remote control valves mouth overflow tank, the hydraulic pump unloading. As the relief valve relief valve.

Safety protection: the normal work of the system when the valve is closed. Only if the load exceeds the prescribed limit (the system pressure exceeds the set pressure) when open the overflow, overload protection, the system pressure does not increase (usually the relief valve set pressure adjustment than the maximum working pressure of the system is 10% ~ 20%).

The general practical application: for unloading valve, remote pressure regulating valve for high-pressure multi-stage control valve for the valve in order to generate pressure (on the back of oil on the road).

The overflow valve generally have two kinds of structure: 1, direct action type relief valve. 2, pilot relief valve.

The main requirements of the overflow valve: voltage range, voltage deviation is small, pressure oscillation, sensitive action, overload capacity, low noise.

Noise and Vibration

Prone to noise in the hydraulic device element is generally believed that the pumps and valves, valve and overflow valve and solenoid valve. There are many factors of noise. Relief valve with flow noise and mechanical noise two. The sound velocity noise is mainly caused by the oil hole and vibration, hydraulic shock and other reasons. The noise mechanical noise from the valve in the main part of the impact and friction and other reasons.

(1) the noise caused by uneven pressure

Part of the pilot valve pilot type relief valve is a vibration prone position as shown in figure 3. In case of overflow when the high-pressure guide valve, the axial opening is very small, only 0.003 ~ 0.006 cm. The flow area is small, the flow rate is high, up to 200 m / s, can lead to uneven pressure distribution, the poppet valve radial force imbalance vibration. In addition, cone and cone valve seat machining ellipse, guide the dirt stuck valve port and regulator spring deformation, will cause vibration of cone valve. It is generally believed that the position of the pilot valve is the source of vibration noise occurs.

As the elastic element (spring) and the moving mass (the cone valve), constitute a condition of oscillation, while the pilot valve chamber before the play the role of a resonant cavity, so after the cone valve vibration occurs easily cause the entire valve resonance and noise, noise occurs accompanied by more general intense pressure to beat.

(2) noise generated hole

When due to various reasons, the air is sucked into the oil, or lower than the atmospheric pressure in the oil pressure, dissolved in the oil in the air will precipitate the formation of bubbles, the bubbles in the low pressure area is larger, when the oil flow to the high pressure area, is compressed, the volume suddenly become smaller or disappear and bubble; as in the high pressure area, volume was smaller, and when the flow to the low pressure area, the volume suddenly increased, the oil bubble volume this rapid change phenomenon. The sudden change of bubble volume will produce noise, and because this process occurs in an instant, the impact will cause the local hydraulic vibration. The pilot valve port pilot relief valve and the main valve port, the oil flow rate and pressure changes greatly, it is prone to cavitation, resulting in noise and vibration.

(3) noise of hydraulic shock

Pilot type relief valve in the unloading, due to rapid pressure hydraulic circuit decreased pressure shock noise. The large capacity high-pressure working conditions, the impact of noise is bigger, this is due to the unloading relief valve is very short due to hydraulic shock resulting in unloading, due to rapid changes in oil flow, the pressure caused by mutation, caused by the impact of the pressure wave. The pressure wave is a small shock wave, the noise itself is small, but spread with the oil system, if there is a mechanical part with any resonance, it may increase the vibration and noise enhancement. So in the event of hydraulic impact noise, and more generally associated with system vibration.

(4) mechanical noise

The mechanical noise of pilot relief valve from the general impact from the components and processing errors such as parts produced by friction.

The noise in the pilot type relief valve, sometimes high-frequency mechanical vibration noise, generally called self-excited vibration sound. This is the main valve and pilot valve for high frequency vibration and sound. Configuration, flow, pressure, temperature and rate of the oil return pipe it (viscosity) and other factors. In general, small diameter pipes, flow, high pressure, oil viscosity is low, the incidence of self-excited vibration is high.

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