Liquid injection device

A liquid injection device, configured to inject at least one working fluid, the liquid injection device comprising:

• a nozzle, comprising at least one channel, at least one bypass passage and at least one suck back passage, the channel penetrating through the nozzle for injecting the working fluid, a liquid outlet defined on a distal end of the channel, the bypass passage comprising a first opening, a switch-on position and a switch-off position, the suck back passage comprising a second opening, the first opening and the second opening communicating with the channel, and the second opening located between the first opening and the liquid outlet;
• at least one moving element, disposed in the bypass passage;
• at least one control valve, disposed on a side of the nozzle, configured to control the moving element to switch between the switch-on position and the switch-off position to open or close the channel;
• and
• a suck back pump, connected to the suck back passage;
• wherein the suck back pump is configured to suck the working fluid remaining between the first opening and the liquid outlet when the moving element is located at the switch-off position.