The solenoid valve and pump works alternatively under the control of host chip.
When the pump works, the solenoid is in a power-off state, and does not work. The spring pushes center post , sealer and framework to form a closed condition. Therefore, air flow cannot pass, and negative pressure is formed in the device for milk suction.
When the suction strength reaches the setting value, the pump stops working, the solenoid valve enters a state of power-on, and starts to work. Solenoid is energized, and forms a magnetic field. Under the function of the magnetic field, the center post is pulled back to the sealer . This results in the sealer and framework forming an open condition. Therefore, air flow can pass, the pressure in the device equals to the outside atmospheric pressure, and milk flows to the milk bottle, because of gravity and air pressure.