1. Technical Field
The invention relates to dispensing a plurality of fluid materials, which when mixed together chemically react to produce a desired end product such as an adhesive, potting compound, sealer, encapsulant or the like. More particularly, the invention relates to a dispenser for dispensing two fluid products in preset amounts, which products are maintained separate until they are mixed prior to being discharged from the dispenser through a nozzle.
2. Background Information
Various types of dispensers have been developed for dispensing a plurality of fluid materials such as chemically reactive resins, or a resin and a hardener, which products must be maintained out of contact with each other within the dispenser so that when mixed, they chemically react to form a final product. It is desirable that the dispenser dispenses the two products in a preset accurately controlled relationship to ensure that the proper chemical reaction takes place when forming the final product, since the final product can be greatly affected by an unbalanced ratio of the two component products.
It is desirable for many applications that the dispenser be a relatively simple and inexpensive device, which preferably can be discarded after discharge of the two components, thereby making it suitable for jobshops, residential users, and the like. Therefore, when intended for use in such applications, the user will normally be unskilled in the dispensing art and will not be concerned with or about, nor experienced in the correct mixing of the two components in forming the final product. Therefore, it is necessary that upon operation of the dispenser, the two products are mixed in the desired relationship without requiring any skill on the part of the dispenser operator.
Examples of the most pertinent prior art dispensers with respect to the dispenser of the present invention are shown in the following patents.
U.S. Pat. No. 4,014,463 discloses a dual component dispenser which uses a hollow delivery tube which extends through a flexible sealing disc at the forward end so that the discharged contents from one of the chambers mixes with the second product discharged from the second chamber at a static mixer nozzle.
U.S. Pat. No. 4,050,612 discloses a dispenser containing two different materials such as creams, wherein an upper chamber is telescopically slidably mounted and moved into a lower chamber for simultaneously discharging products from each of the containers at a pair of adjacent openings.
U.S. Pat. No. 4,029,236 discloses another two product dispenser having an upper chamber which is telescopically moved over and downwardly along a second chamber whereupon the contents of the two chambers are dispensed, generally simultaneously through two separate dispensing tubes. A vent tube is provided in the dispenser to prevent the formation of a vacuum within the dispenser upon dispensing of the product to ensure the smooth movement of the two chambers with respect to each other.
U.S. Pat. No. 4,220,261 discloses another dual dispenser in which an air intake is provided in a dispensing tube, as well as an annular air space being provided between the walls of the two cylindrical chambers, to prevent the formation of a vacuum therebetween during operation of the dispenser.
U.S. Pat. No. 4,961,520 discloses another dual product dispenser whereby a free space is provided so that a second plunger is actuated only after a predetermined movement of another plunger in order to prime the dispenser and prevent premature discharge of the flowable product from within a plunger cup.
Although the above discussed patents are believed to be the most pertinent with respect to the present invention, still other examples of various product dispensers are shown in U.S. Pat. Nos. 2,001,819, 3,164,303, 4,366,919, 4,371,094, 4,676,657, 4,691,845, 4,735,509, 4,799,801, 4,826,047, 4,834,714, 4,941,751, 5,058,770, 5,065,906 and 5,139,171.
Although many of these prior art dual product dispensers perform satisfactory for their intended dispensing purpose, many of these dispensers are difficult to easily fill the two separate chambers with the two distinct products, while maintaining complete separation of two products from each other. Likewise, certain of these prior art dispensers are relatively expensive, especially when the dispenser is intended to be mass produced in large quantities. Thus a savings of only a few cents per dispenser over similar prior art dispensers will result in a cost savings and competitive advantage.