This invention relates generally to fluid dispensers, and specifically to a class of fluid dispensers adapted for attachment to fluid containers such as flexible plastic bags.
The use of plastic bags as fluid containers has become widespread, particularly in certain applications. For example, food liquids, such as milk and wine, are commonly packaged and distributed in plastic bags. The filled bags are usually carried in a cardboard box. A rigid plastic dispenser is attached to the bag in a manner to extend through the box in order to dispense liquid from the bag. The dispenser normally includes a valve which is operated between open and closed positions by the ultimate user of the product, in order to periodically remove liquid from the bag. As liquid is removed from the flexible plastic bag, the bag collapses around the remaining liquid. Since it is unnecessary that air be introduced into the container in order to remove liquid, air does not come into contact with the remaining food material in the bag.
During shipping and storage, the bag remains sealed. One type of commercial dispenser includes a cutting element for making an opening in the bag wall. The first time the dispenser is operated to withdraw fluid from the bag, the cutting element cuts a hole in the bag wall. Prior to this time, the bag has remained totally sealed. A manually operated valve provided as part of the dispenser thereafter controls flow of the fluid out of the bag through the bag opening. Such an arrangement is described in U.S. Pat. No. 4,355,737 Pongrass and Rutter (1982). When this type of dispenser is used, the bag is initially filled through an opening that is heat sealed shut after filling.
Another type of commercial dispenser is attached to a bag that includes a hole pre-punched in its wall. Before attaching the dispenser to the bag, it is filled through the hole with liquid, particulate material, or other fluid desired to be stored and shipped in it. A rigid plastic spout is usually first attached to the bag around the hole. A dispenser is then attached to the spout and seals the bag opening by a diaphragm extending across the fluid passage within the dispenser. This diaphragm is then cut when the user first opens the dispenser valve to remove fluid from the bag. An example of this type of dispenser is given in Canadian Patent No. 1,206,923--Rutter (1986). In this dispenser, a semicircle is cut in the diaphragm, leaving a flap that is moved out of the dispenser fluid passage by fluid flow through it from the bag.
Although the valves provided as part of either of these two types of dispensers are quite adequate for closing off fluid flow once use of the bag is commenced, the simple structure of such valves is usually not relied upon to prevent fluid loss during extended storage and shipment. That is why the bag is otherwise sealed during such storage and shipment, this seal being broken when the valve of the dispenser is first operated to an open position by the end user of the container.
It is an object of the present invention to provide a dispenser of the type having a sealing diaphragm therein with an improved structure for breaking the seal and allowing free fluid flow through the dispenser after the seal is broken.