Pumps with positive pressure venting, refill units and dispensers
Exemplary embodiments of pumps having positive pressure venting and refill units are disclosed herein. An exemplary pump includes a liquid pump chamber, a liquid piston, a first air pump chamber, and a first air piston and a mixing area in fluid communication with the liquid pump chamber and the first air pump chamber. The exemplary pump further includes a second air pump chamber and a second air pump piston. The second air pump chamber is configured for pumping air into a container and the first air piston and the second air piston move in unison.
1. A foam pump comprising:
a liquid pump chamber;
the liquid pump chamber defined at least in part by a housing; a liquid inlet valve and a liquid outlet valve;
a liquid piston moveable within the liquid pump chamber;
an air pump chamber;
an air pump piston movable within the air pump chamber;
wherein when in use, compression of the liquid pump chamber and the air pump chamber causes liquid and air to be mixed together and dispensed from the foam pump in the form of a foam;
an air vent chamber;
the air vent chamber defined at least in part by a housing; an air inlet valve and an air outlet valve;
an air vent piston movable within the air vent chamber;
wherein when in use, movement of the air vent piston in the air vent chamber to compress the volume of the air vent chamber causes the air inlet valve to open allowing air to flow into a container secured to the foam pump and wherein sufficient vacuum pressure in a container connected to the foam pump will cause the air inlet valve to open allowing air to flow into the container.
2. The foam pump of claim 1 wherein an air outlet of the air vent chamber is located above a liquid inlet of the liquid pump chamber.
3. The foam pump of claim 1 wherein the air vent piston has a piston stem and a shuttle valve.
4. The foam pump of claim 3 wherein the shuttle valve comprises an opening through a center, wherein the opening is larger than a portion of the piston stem.
5. The foam pump of claim 3 wherein the shuttle valve has one or more openings in the surface of the shuttle valve configured to allow air to flow past.
6. The foam pump of claim 3 wherein the piston stem comprises a seat for engaging a surface of the shuttle valve to close the shuttle valve.
7. The foam pump of claim 3 wherein the shuttle valve includes a pressure relief member.
8. The foam pump of claim 1 wherein the air vent chamber is in fluid communication with the air pump chamber.
9. The foam pump of claim 1 wherein the air vent outlet valve is configured to open when a selected vacuum pressure is developed in a container.
10. The foam pump of claim 3 wherein when the shuttle valve is in a first position, air can flow past the shuttle valve and when the shuttle valve is in a second position, air does not flow past the shuttle valve.
11. The foam pump of claim 1 wherein the liquid pump chamber and the air vent chamber have about the same volume.
12. The foam pump of claim 1 wherein the liquid pump chamber has a greater volume than the air vent chamber.
13. The foam pump of claim 1 wherein the foam pump is configured to vent a container using positive pressure when the air vent piston compresses the air vent chamber and is configured to vent the container if a selected vacuum pressure is in the container.
14. A pump comprising:
a liquid pump chamber;
a liquid piston;
a first air pump chamber;
a first air piston;
a mixing area in fluid communication with the liquid pump chamber and the first air pump chamber;
a second air pump chamber;
a second air pump piston;
the second air pump chamber configured for pumping air into a container;
wherein the first air piston and the second air piston move in unison.
15. The pump of claim 14 further comprising a vent valve in fluid communication with the second air pump chamber.
16. The pump of claim 15 wherein the vent valve is configured to open when a selected vacuum pressure is developed in a container.
17. The pump of claim 14 wherein the second air pump piston comprises a shuttle valve.
18. The pump of claim 17 wherein when the shuttle valve is in a first position, air can flow past the shuttle valve into the second air pump chamber and when the shuttle valve is in a second position, air does not flow past the shuttle valve.
19. A refill unit comprising:
a container;
a pump secured to the container;
the pump having
a liquid pump chamber;
a liquid pump piston;
a first air pump chamber;
a first air pump piston;
a mixing area downstream of the liquid pump chamber and the first air pump chamber for receiving liquid from the liquid pump chamber and air from the first air pump chamber;
an outlet downstream of the mixing area for dispensing a liquid and air mixture;
a second air pump chamber;
a second air pump piston;
a vent valve secured to the second air pump chamber;
wherein the second air pump chamber has a volume that is about the same volume as the liquid pump chamber; and
wherein the second air pump chamber pumps air into the container.
20. The refill unit of claim 19 wherein the vent valve is configured to open when the volume of the second air pump chamber is compressed and is configured to open when the vacuum pressure in the container is greater than the cracking pressure of the vent valve.