Piezo-pneumatic valve driving type dispensing pump and method of dispensing viscous liquid by using the pump

摘要

A piezo-pneumatic valve driving type dispensing pump having an improved dispensing speed and a simplified structure, and a method of dispensing a viscous liquid by using the pump. Accordingly, a viscous liquid may be easily dispensed by reciprocating a valve rod inserted into a reservoir storing the viscous liquid, by using an air pressure. In particular, the air pressure may be precisely controlled by opening or closing a flow passage allowing the air to enter or exit, by using a piezoelectric element-based piezoelectric valve. Thus, the valve rod may be operated precisely at a high speed so that an exact amount of the viscous liquid is dispensed at a high speed.

主权项

1. A liquid dispenser comprising:
a cylinder; a piston operably engaged with the cylinder and configured to slide relative to the cylinder, the cylinder and the piston defining an air chamber; a liquid valve assembly comprising a nozzle and a valve rod with a tip facing the nozzle, the valve rod connected to the piston and configured to move along an axis relative to the nozzle as the piston slides relative to the cylinder; a first air channel connecting the air chamber to a positive air pressure supply; a second air channel connecting the air chamber to a negative air pressure supply; a first piezoelectric valve comprising a first piezoelectric actuator configured to expand and shrink in accordance with a first voltage signal applied thereto, thereby causing to open and close the first air channel for selectively applying positive air pressure to the air chamber from the positive air pressure supply; a second piezoelectric valve comprising a second piezoelectric actuator configured to expand and shrink in accordance with a second voltage signal applied thereto, thereby causing to open and close the second air channel for selectively applying negative air pressure to the air chamber from the negative air pressure supply; electric circuits configured to generate the first voltage signal for applying to the first piezoelectric actuator and further to generate the second voltage signal for applying to the second piezoelectric actuator such that the first and second voltage signals are to alternatingly open the first and second air channels without both being fully open at any time during normal operation, wherein when the first and second voltage signals cause to open the first air channel and to close the second air channel, positive air pressure is applied to the air chamber via the first air channel to move the piston in a first direction, which to cause the tip of the valve rod to move along the axis toward or away from the nozzle for controlling liquid dispensing, wherein when the first and second voltage signals cause to close the first air channel and to open the second air channel, negative air pressure is applied to the air chamber to move the piston in a second direction opposite to the first direction, which to cause the tip of the valve rod to move along the axis toward or away from the nozzle for controlling liquid dispensing.