Patent Application
20080179554
Not Applicable.
Not Applicable.
This invention relates to a valve member, and more particularly to an improved valve member for a gun used to dispense fluid components.
Manually operable guns are known for dispensing fluids. For example, one type of gun dispenses settable urethane foam. In operation, separate fluid components are fed individually to the gun, passed separately through valve members, and brought into contact with each other upon reaching a mixing chamber of a nozzle. The mixed components are then discharged from the nozzle as foam. Examples of such guns are found in U.S. Pat. Nos. 4,311,254 and 4,399,930 issued to Gary Harding, in U.S. Pat. No. 4,762,253 issued to Steven Palmert, and in U.S. Pat. No. 5,462,204 issued to Clifford Finn.
In foam-dispensing guns, two fluid components are typically used and commonly referred to as the “A resin” and the “B resin.” The A and B resins usually consist of polymeric isocyanate and polyol amine, respectively. The components are supplied separately in two pressurized containers that are attached by hoses to inlets of the guns. When the two fluid components or resins are mixed, the mixture quickly forms a rigid foam product that is substantially insoluble and extremely difficult to remove from surfaces with which it comes in contact. As a result, the valve members and valve seats within the nose of the gun body are designed to have a tight fit in order to force all of the A resin and B resin into the nozzle when the valve members are in the closed position.
It is also important to keep the components separate within the gun so that their only contact is in the mixing chamber of the disposable nozzle. Furthermore, the A resin, has a tendency to harden on exposure to air. As a result, should either the two components mix within the valve members or the A resin be exposed to air, the valve members would clog and cease to correctly operate.
The use of economical, durable plastic as the preferred material for many components of a dispensing gun has presented additional challenges. It has become apparent that costly secondary operations are often required to manufacture certain components because of manufacturing tolerances and material variations. Variations arise due to uneven shrinkage of the plastic, weld lines within the formed plastic, flashing caused by the forming process, and the like. All of these factors create inconsistencies and irregularities in the fit of mating components of a dispensing gun.
The metering interface between the valve member and the valve seat is of particular concern. If the valve member does not both expel substantially all of the resin into the nozzle and create an airtight seal between itself and its seat, closing off the resin from the nozzle, the components of the gun may clog and become unusable or operate at less than the desired level. Therefore, the increased use of plastics to form the metering interface between the valve member and valve seat has created a practical problem, which previous designs have proven inadequate at resolving.
The invention is advantageous in that it provides an improved valve member and dispensing gun that prevents set up or hardening of components within the metering interface such that the metering interface remains free of contaminants and is consistently operable at peak design parameters.
Another advantage of the invention is substantially to expel fluids from the metering interface, and to prevent contaminants or fluids from entering the valve seats from downstream when the valves are in the closed position, despite inconsistencies and irregularities in the metering interface (e.g., valve seats and valve members).
Additional advantages and features of the invention will become apparent from the description that follows. In the description, reference is made to the accompanying drawings, which illustrate preferred embodiments of the invention and do not limit the scope of the invention as stated in the claims.
The improved valve member and dispensing gun will be discussed, without limitation, in relation to a foam-dispensing gun incorporating two valve members 31. One skilled in the art will appreciate the multitude of alternative configurations that do not exceed the scope of the present invention. Referring to
The upstream portions of the passageways 12, 13 mount brass connectors 15 that have a ribbed end for attachment to hoses connected to pressurized containers for fluid components that are used to form the foam. The connectors 15 are held in place in the body 10 by setscrews 16 extending transversely to the passageways 12, 13 and received in annular recesses 17 in the connectors 15. The connectors 15 each have a second annular recess 18 interior of the body 10. The second annular recess 18 mounts an O-ring 19 that seals with the upstream portion of the passageway 12, 13.
Brass bushings 22 are mounted in the passageways 12, 13 downstream of the connectors 15. The bushings 22 include annular recesses 23 to mount O-rings 24 that seal with the upstream portions of the passageways 12, 13.
As shown in
Each bushing 22 is disposed against a bellville spring 26 that bears against an end of the respective connector 15 thereby urging the bushing 22 downstream in the passageway 12, 13 until it abuts against a shoulder 27. A coiled spring 30 is disposed in each of the passageways 12, 13. The spring 30 bears at one end against an end of a respective bushing 22. The other ends of the springs 30 bear against the ends of valve members 31 (discussed in more detail below) also disposed in the passageways 12, 13.
The chamber 14 mounts a yoke 50 formed at the top of a trigger lever 51. The yoke 50 has a pair of arms 52 terminating in lateral bosses 53 that are received for pivotal movement in holes 54 in the two sides of the body 10, as shown in
Each valve member 31 has an internal passage 60 that terminates in a transverse port 61 disposed upstream of the metering portion 41 (discussed in more detail below) and extends to the surface of the valve member 31. As shown in
A disposable nozzle 65 is mounted on the nose 40. The nozzle 65 has a hollow interior that defines a mixing chamber 66 and an outlet 67. A helical static mixer 68 of known construction is mounted in the mixing chamber 66. The upstream end of the nozzle 65 has an enlarged circular cylindrical portion 69 that surrounds the nose 40 of the body 10 and is sealed thereto by an O-ring 70. A pair of resilient arms 71 extend along either side of the nozzle 65 rearwardly from the enlarged cylindrical portion 69. The resilient arms 71 are adapted to engage ears 72 that extend from opposite sides of the body 10 adjacent the nose 40. The resilient arms 71 have a curved portion 73 adjacent their ends, which terminate in a notch 74, that mate with an ear 72. The nozzle 65 can be quickly attached to, or removed from, the body 10 by sliding the resilient arms 71 beneath the ears 72.
The static mixer 68 includes a wall portion 76 that is located in the open inlet chamber defined by the enlarged cylindrical portion 69 of the nozzle 65. As shown in
A safety can be provided to prevent the accidental movement of the trigger 51. The safety comprises a rod 80 having a bulbous end 81 that rides in a channel 82 along the inside of the trigger lever 51. The rod 80 is supported in a bore 83 in the handle 11 and terminates in a transverse handle 84. A spring 85 is disposed between a shoulder 86 formed by a counterbore 87 and a shoulder 88 on the rod 80. Although the safety is shown and described, the safety can be omitted without departing from the scope of the invention.
With the general structure of the foam-dispensing gun described, an embodiment of the valve member 31 of the invention will be discussed in greater detail with reference to
In general, the valve member 31 meters the flow of fluid from the connected upstream tanks (not shown). As previously noted, when in the closed positions, shown in
The valve members 31 of the preferred embodiment include two main sections, namely, a valve body 35 and a metering portion 41 downstream of the valve body 35. In the preferred embodiment, the valve body 35 includes two seals, an upstream seal and a downstream seal. The upstream seal is preferably comprised of an upstream cylindrical portion 110 having an upstream annular recess 120 with an upstream O-ring 33 seated therein. The upstream seal prevents fluid from traveling downstream past the upstream end of the valve body 35. The downstream seal is preferably comprised of a downstream annular recess 118 with a downstream O-ring 46 seated therein. The downstream seal prevents fluid from traveling upstream of the downstream end of the valve body 35 and into the chamber 14. Both the upstream and downstream seals act to prevent contaminants from entering into the fluid passageways 12, 13 from the chamber 14.
The metering portion 41 of the valve member 31 extends downstream from the valve body 35 of the preferred embodiment. The metering portion 41 mates with a valve seat 37 to establish a metering interface 39 used to meter the flow of fluid through the passageways 12, 13 and creates a seal blocking the respective passageway 12, 13 downstream of the metering interface when the valve member 31 is in the closed position.
In the preferred embodiment, the metering portion 41 has a frusto-conical portion 112 that mates with a substantially matching valve seat 37 formed in the nose 40 of the body 10. An O-ring 122 is seated in the metering annular recess 116 creating a seal downstream of the metering interface 39 between the frusto-conical portion 112 and the valve seat 37 when the valve is closed, as shown in
As shown in
While the embodiment depicted in
Furthermore, the valve members 31 need not have a cylindrical cross-section. As shown in
Furthermore, turning to
An alternative valve member 31B is illustrated in
The valve members 31 are preferably made of brass, but may be made of other metals, plastics, composites, and the like. Advantageously, with the development of the present invention, the valve members 31 may be made of materials having larger manufacturing tolerances because the present invention ensures that the variations at the metering interface 39 do not adversely affect the operation of the dispensing gun. Additionally, the body 10 of the dispensing gun may now be made of various materials, such as plastic and composites, that too have a larger manufacturing tolerance, without the need for costly secondary manufacturing techniques currently required to produce dispensing guns.
Although the present invention has been described with reference to certain embodiments, one skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which have been presented for purposes of illustration and not of limitation. Therefore, the scope of the appended claims should not be limited to the description of the embodiments contained herein.
