Diaphragm pump

A diaphragm pump comprising:

• a syringe storing a viscous liquid;
• a transfer flow path provided with a pressing hole formed to have an opened side and connected to the syringe to be supplied with the viscous liquid;
• a housing coupled to the transfer flow path;
• a diaphragm installed in the housing so that at least a part thereof is exposed through the pressing hole of the transfer flow path and the viscous liquid in the transfer flow path is pressed through elastic deformation;
• a plunger installed to be slidable with respect to the housing so as to press the diaphragm and elastically deform the diaphragm;
• an actuator unit operating the plunger to be moved forward/backward with respect to the housing;
• and
• a nozzle connected to the transfer flow path so that, when the diaphragm is elastically deformed by the plunger and presses the viscous liquid, the viscous liquid is discharged to outside,
• wherein the housing includes a plunger seating portion formed as a cylinder,
• the plunger is formed as a piston type and installed in the plunger seating portion, and
• the actuator unit operates the plunger by transferring a pneumatic pressure to the plunger seating portion of the housing,
• wherein the housing includes a feeding port for transferring external compressed air, an operating port being in communication with the plunger seating portion, and a discharge port for discharging compressed air in the housing to outside, and
• the actuator unit operates the plunger by alternately connecting the feeding port and the discharge port to the operating port,
• wherein the housing further includes a spool seating portion that is formed at a position where the spool seating portion is in communication with each of the feeding port, the discharge port, and the operating port, and
• the actuator unit comprises
• a rotary spool installed in the spool seating portion of the housing to be rotatable, a motor for rotating the rotary spool, and a first flow path and a second flow path that are formed in the rotary spool so as to connect the operating port to each of the feeding port and the discharge port according to a rotating angle displacement of the rotary spool.