We know that when the vacuum pump is finished, when it is shut down, Because the pump cavity is in a vacuum state, the pump oil will be returned to the pump cavity. The amount of pump oil is large, some will fill the whole pump cavity, and some can even enter the front pipe. When the pump is started again, a large amount of pump oil will be discharged. After the pump oil is compressed, the temperature rises and the valve plate is impacted. Most of the oil exists in the form of small oil drops, and it is easy to be taken out of the pump under the promotion of large air flow This will cause the phenomenon of pump injection.
To solve this problem, it is necessary to stop the pump at the same time, quickly inflate the pump cavity, damage the vacuum in the pump cavity, so that the pump oil has no ability to recharge. This requires a differential pressure valve at the pump port.
However, the speed of gas recharging is very slow, and the function of differential pressure valve is only to prevent oil from recharging to the front section of differential pressure valve, which can not meet the purpose of preventing oil from entering the pump cavity. Therefore, it is necessary to expand the air filling port of the differential pressure valve to make the air flow into the pump cavity quickly, so as to make the gas pressure in the cavity reach the pressure of the pump oil recharging pump cavity in a short time, so as to reduce the oil return volume of the pump cavity.
In addition, a solenoid valve can be set at the oil inlet pipe of the pump chamber. When the pump is turned on, the solenoid valve opens to make the oil circuit unobstructed. When the pump stops, the solenoid valve closes the oil circuit, which can also control the oil return.
Post time: Aug-05-2020