An emulsion pump mainly comprises a piston rod, a pressing head, a screw-topped sleeve, a cylinder, a spring, a rubber pipe and a gasket. Among them, the upper screw thread of the cylinder engages with a screw thread portion of the screw-topped sleeve. The width of the teeth of the upper end screw thread of the cylinder is A, the width of the gullet the screw thread portion of the screw-topped sleeve which is connected with the screw thread of the cylinder is B, and B is greater than A, thereby a gap exists between them; in addition, a gap is also formed between the contact surface of the upper end of the cylinder and the lower surface of the top portion of the screw-topped sleeve, thereby an air channel for preventing liquid entrance is formed in the emulsion pump.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of International Patent Application PCT/CN02/00326, filed on May 13, 2002, which claims priority to Chinese Patent Application 01221317.9, filed on May 16, 2001, the contents of both are incorporated herein by reference.
An airless dispenser pump assembly includes a pump mechanism with an inlet valve that is configured to efficiently pump viscous fluids and that is able to be pre-primed when the pump mechanism is attached to a container. In one form, the inlet valve includes a seal member that seals an inlet port of the pump and an outer support member that secures the inlet valve to the rest of the pump mechanism. Two or more legs generally extend in a circumferential direction between the support member and the seal member in order to create a large flow opening for fluid flow through the inlet valve when opened and to rapidly close the inlet valve. The pump mechanism further includes an outlet valve that is configured to draw fluid back from a nozzle of the pump after dispensing in order to minimize build up around the nozzle.
