Dispensing gun assembly for mixing and dispensing plural component foam

A dispensing gun assembly including a gun body having a handle and a housing attached to the gun body. The housing includes first and second fluid passageways and first and second valve receiving bores. The fluid passageways are segregated from one another within the housing. First and second valves are received in the valve receiving bores. Each valve has open and closed positions and the valves move within the valve receiving bores when changing between the open and closed positions. A trigger member controllably contacts the valves and a nozzle assembly is connected to the housing.

STATEMENTS REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an apparatus for mixing and dispensing plural component foams, and more particularly, to a dispensing gun for mixing and dispensing a two-component urethane foam utilizing pressurized gas. Preferably, the dispensing gun is a disposable-type gun suitable for use as part of a disposable foam component kit.

2. Description of the Related Art

In recent years, improvements have been made in dispensing plural component synthetic materials, primarily foams, many of which are urethane foams or those involving similar chemistry. In such foams, an “A” or isocyanate component and a “B” or resin component are mixed in a mixing chamber adjacent the point of dispensing and the thus-formed mixture reacts in or near the dispensing nozzle. The combination of the heat from the reaction between the resin and the isocyanate components, and the reduced pressure resulting from passage outside a pressurized container causes a dissolved liquid propellant, such as a halocarbon of low boiling point, to expand and create a froth. Such expansion can also be used to create a propulsive force.

Systems of this sort have been placed in widespread use and have made it possible for a wide variety of users to derive the benefits of on-site generation and dispensing of urethane foam for purposes of insulation, flotation, void fill and the like. Further development enabled urethane foam to be mixed on-site and dispensed from kits that were light enough to be portable by users, and yet large enough to dispense significant quantities of foam. Typically, the kits that are readily portable are capable of mixing and dispensing 100-600 board feet of uniformly high quality urethane foam. Such foam usually has a finished density of 1.5 to 4.5 pounds per cubic foot (“pcf”) and provides buoyancy, adhesion, structural rigidity and outstanding thermal insulation.

When the “A” and “B” components are mixed in proper proportions, they typically react quickly to form and solidify into an expanded foam. Foam dispensing guns must, therefore, be kept free from buildup of the foam components and resulting expanded foam, so that control valves and passageways do not become clogged, rendering the foam dispensing gun inoperable.

U.S. Pat. No. 5,529,245 discloses a low cost mixing and dispensing gun with a valve body containing a pair of liquid inlets, a pair of separate liquid outlets, a gas outlet and a removable mixing and dispensing nozzle. The nozzle contains the ingredients while they are being mixed and a gas outlet is positioned within the nozzle so as to propel the mixed ingredients to the application area.

There is a need for a foam dispensing gun having improved reliability and performance. It is desirable to have a foam dispensing gun with improved component mixing capabilities. It is also desirable to have these improved features in a foam dispensing gun suitable for throw-away use with a disposable portable foam component kit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Referring toFIG. 1, a dispensing gun assembly according to a preferred embodiment of the present invention, generally designated10, is shown to include a gun body12having a handle14, a flow control valve housing16, a nozzle receiver assembly18, a removable nozzle assembly20, a nozzle latch assembly22, a trigger member24, a trigger safety26, and first and second component inlet hoses28and30, each terminating in fittings31and33, respectively.

Referring now toFIGS. 2A and 3A, it is shown that the nozzle assembly20includes an outlet tip portion32, a static mixer portion34, and a premix chamber36. The nozzle assembly20also includes a latch-engaging surface38and an ejector-engaging rear face40as shown inFIG. 3A. At the inlet end of the nozzle assembly20, a pair of nozzle inlet nipples44and46are provided, each of which is adapted to seat within outlet passages45and47in the flow control valve housing16as shown inFIG. 4. Each of the inlet nipples44,46includes a plurality of flexible, outer plastic sealing ribs48and an inlet throughbore49.

Referring toFIGS. 1,2A and2B, the gun body12includes the handle14that is preferably contoured to provide a comfortable, ergonomic fit in a user's hand. The handle14includes a vertically extending recess50(FIG. 1) adapted to receive a center rib52of the trigger safety26when the trigger safety26is in a folded, disengaged or “off” position as shown inFIG. 2B. The handle14also includes an opening54adapted for reception of a pivot pin56. The pivot pin56pivotally secures the trigger safety26to the handle14. The pivot pin56may be integrally formed on the trigger safety rib52or extend through a hole in the rib52. The handle recess50also provides a convenient receptacle for a portion of a trigger return spring60shown to be of the “clothespin” type, operating in response to torsional forces generated in its center coil59. Although not shown, it is to be understood that the trigger member24preferably includes a recess for receiving a second portion of the trigger return spring60.

Referring toFIGS. 4 and 5, the upper portion of the gun body12includes the flow control valve housing16. The flow control valve housing16includes a valve receiving bore62extending transversely to the principal axis of the housing16. The control valve housing16also includes a pair of product flow passageways64and66extending axially through the housing16as shown inFIG. 4.

Referring toFIG. 1, surmounting the housing16is the nozzle latch assembly22. The nozzle latch assembly22includes a latch receiver76having generally parallel side walls78,80, designed to snugly engage a latch and ejector member74when in the locking position. Each side wall78,80includes a small opening82for receiving a pivot pin84extending through a hole (not shown) in the latch and ejector member74. This latch and ejector member74is shown to comprise a rocker-style lever assembly having a finger tab86lying to one side of the pivot pin84and generally horizontally and vertically extending legs88and90, respectively, on the opposite side of the pivot pin84. The end portion of the latching leg88terminates in a claw92, while a front face94of the ejector leg90acts to engage the rear face40of the nozzle assembly20as shown inFIGS. 3A and 3B. Preferably, the latch receiver76has its side walls78,80spaced such that these walls snugly engage the legs88,90of the latch and ejector member74, preventing it from moving freely and inadvertently ejecting the nozzle assembly20.

The nozzle receiver assembly18is disposed at the forward end of the housing16and includes a nozzle guide surface96terminating at its inner end in a front wall portion98. The outlet passages45and47form a forward portion of the product flow passageways64and66and extend through the front wall portion98to the valve receiving bore62as shown inFIGS. 3A,3B and4.

Referring toFIGS. 4-6, first and second rotary valves100and102, respectively, have a cylindrical body104with a pair of circumferential recesses106, each adapted to receive a seal108, preferably an O-ring seal. The body104includes a transverse fluid port110extending therethrough. An ear112extends from one end of the cylindrical body104. Preferably, the ear112is positioned slightly off-center of the principal axis of the cylindrical body104such that the ears112of the valves100and102overlap each other in abutting contact when the valves100and102are in the valve receiving bore62as shown inFIG. 4.

Referring toFIG. 5, a pair of grooves114, formed in the receiving bore62, receive retaining rings116, preferably snap rings, for retaining the rotary valves100and102within the valve receiving bore62. Preferably, the ears112have an end surface118which abuts the cylindrical body104of the other valve and the spacing between the retaining rings116is designed to accommodate the two valves100and102with their overlapping ears112and restrict valve movement along the principal axis of the valve receiving bore62while allowing rotational movement about the principal axis.

As shown inFIG. 5, the cylindrical body104has a diameter slightly less than the diameter of the valve receiving bore62. A seal108is located on each side of the fluid port110. The pair of seals108of each valve100,102form a fluid seal between the cylindrical body104and the bore62of the housing16.

Referring toFIGS. 3A,3B,4and5, the trigger member24includes an upper slot120extending through the trigger member24. The upper slot120is adapted to receive the overlapping valve ears112. The upper slot120is preferably the shape of the overlapping ears112, which in the preferred embodiment is rectangular. The upper slot120is sized and shaped to receive the overlapping ears112with a minimal clearance.

As shown inFIG. 5, the valve housing16includes a trigger receptacle68for receiving the upper end of the trigger member24. The trigger member24is installed by sliding the first and second rotary valves100and102, respectively,. into the receiving bore62from opposite ends of the bore62. The trigger slot120is positioned in the trigger receptacle68as the valve ears112enter the trigger receptacle68. The valves100,102may need to be rotated to align the ears112with the trigger slot120. Upon proper alignment, the valves100,102are fully inserted in the valve receiving bore62with the ears112overlapping each other and the ear end surfaces118abutting the opposing valve body104. Upon full insertion of the valves100and102, the retaining rings116are installed in the grooves114.

The trigger member24depends from the overlapping ears112and pivots about the principal axis of the valve receiving bore62. Rotational movement of the trigger member24results in corresponding rotational movement of the valves100and102.

Preferably, when the trigger member24is in the open position (seeFIGS. 2B and 3B), the fluid port110of each valve100,102is in fluid communication with the corresponding outlet passage45,47. When the trigger member24is in the closed position (seeFIGS. 2A and 3A), the fluid port110of each valve100,102is not in fluid communication with the corresponding outlet passage45,47.

Referring toFIGS. 3A,3B,4and6, a pair of rotary valve seals122, preferably of teflon, each having an arcuate surface124corresponding to the cylindrical valve body104, is held in contacting relationship with the valve body104. The valve seal122includes a port126which aligns with the transverse fluid port110when the trigger member24is in the open position as shown inFIG. 3B. Preferably, the valve seal122has a width no greater than the spacing between the pair of seal recesses106in the valve body104as shown inFIG. 4. This allows each seal108to form a continuous seal with the wall defining the valve receiving bore62.

As shown inFIG. 6, behind the rotary valve seal122is preferably a washer128, a filter ring130and filter screen132, a washer134, preferably a spring-type washer such as a Belleville washer, and the hose connector fitting31or33received in each product flow passageway64,66(FIG. 4). Preferably, each fitting31,33includes an enlarged portion135having a plurality of seal recesses136for receiving a plurality of seals138, preferably O-ring seals. Preferably, each fitting31,33also includes a retaining groove140to receive a retaining member142, for example a pin or screw, inserted through a hole144in the flow control valve housing16.

Referring now toFIGS. 1 and 3A, the assembled gun10is shown in an inactive position of use with the trigger24forward and the rotary valve102in a closed position. As shown inFIG. 1the gun body12is shown assembled with a pair of component inlet hoses28and30(in phantom lines) connected to the hose connector fittings31and33. The product flow passageways64and66include a large smooth counter bore64aand66a, respectively, in the housing16. The annular seals138on the large portion135of the hose connector fittings31,33facilitate sealing of the fittings31,33within the large smooth counter bore64a,66ain fluid-tight relation as shown inFIGS. 3A and 4. The retaining members142(FIG. 4) removably hold the fittings31,33in place in the counter bores64a,66a.

As shown inFIG. 3A, the rotary valves102and104are positioned such that fluids may not flow through valve fluid ports110when the trigger24is in its forward or closed position. As shown inFIG. 2A, the return spring60forces the trigger24to its forward position and the safety26is shown in its engaged position to lock the trigger24in its closed position. In the closed position, the fluid port110of each rotary valve100,102is out of registry with either of the adjacent passages, those being the valve seal port126and the outlet passage45,47. Forward product flow from the supply hoses28,30is blocked by the sealing engagement of the arcuate surface124of the rotary valve seal122with the surface of the cylindrical body104of the valve100,102in addition to the sealing engagement of the valve cylindrical body104with the valve receiving bore62. Preferably, the spring-type washer134indirectly maintains an axial force on the valve seal122in the direction of the valve100,102.

The combination of the various bores and passages, including those in the hoses28,30, connector fittings31,33washers128,134, rings130and screens132, and seals122, combine to comprise a pair of inlet passages. Flow through the outlet passages45and46is controlled by the movement of the rotary valves100and102. In the preferred embodiment, the housing16contains coaxially aligned pairs of passages and a flow control valve for each passage. In the preferred embodiment as shown inFIG. 4, there are no closed passageways or cavities interconnecting the aligned pairs of fluid passages in the gun body12which eliminates the possibility of the fluid components leaking past seals and reacting with each other to cause premature operation failure. As described above and as shown inFIG. 5, the valve receiving bore62containing the valves100,102is in actuality two aligned bores62aand62bseparated by the intermediate trigger receptacle68.

As shown inFIG. 2B, the safety26has been moved to a disengaged position and the trigger24has been pulled to a fully opened position compressing the spring60. Fluid is thus free to flow through the passages formed as described above. The separated fluid components enter the removable nozzle assembly22where they initially mix and react with each other prior to being dispensed from the nozzle opening42.

Referring toFIGS. 3A and 3B, the claw92on the latch and ejector member74engages the latch-engaging surface38of the nozzle20during operation of the dispensing gun assembly10. The ejector-engaging rear face40of the nozzle20abuts or is adjacent the front wall portion98of the nozzle receiver assembly18, while the front face94of the ejector leg90engages or is adjacent the nozzle rear face40in the area between the nozzle nipples44and46.

When it is desired to remove the nozzle assembly20from the gun body12, the nozzle assembly20can be ejected by depressing the finger tab86of the latch and ejector member74. Upon depressing the finger tab86, the latch and ejector member74pivots about the pivot pin84and provides both an ejection lever action and an unlocking or unlatching action. The pivoting movement results in a cooperative action between the nozzle receiver assembly18and the nozzle20. Depressing the finger tab86both releases the latch claw92and causes the ejector leg90to rotate against the nozzle rear face40and eject the nozzle assembly20. When reloading a nozzle assembly20, the full insertion of the nipples44and46in the outlet passages45and47results in the ejector leg90retracting and the latch claw92engaging the latch-engaging surface38of the nozzle20.

In its preferred form, the entire gun just described may be made from plastic materials, with the exception of the rotary valves, the fasteners, and the hose end fittings. An advantage of the preferred embodiment of the present invention is that there is completely separated fluid component passages through the gun body12which eliminates the possibility of the chemical streams from “crossover” and reacting inside the flow control valve housing16.

Preferably, the nozzle assembly20includes the premix area36adjacent to where the component streams enter the nozzle assembly20prior to passing through a static mixer34A in the static mixer portion34and exiting through the outlet tip portion32. The static mixer34A may include a plurality of joined helical sections in which each section is rotated approximately 90 degrees (90°) from the adjacent section. The static mixer34A as described and shown is known in the art. It is to be understood that the static mixer34A has been omitted fromFIGS. 3A,3B and7.

Referring toFIG. 4, the nozzle assembly20preferably includes a baffle or deflector37to redirect each component stream in the premix area36. The deflector37is preferably substantially transverse to the direction of the fluid streams as they exits the inlet nipples44and46. The deflectors37interrupt the laminar flow of each stream and preferably redirects each stream approximately 90 degrees (90°) so that the two streams impinge each other within the premix area36. Impinging the two streams within the premix area36improves the material mix through the static mixer portion34.

In use, the remote ends of the hoses are connected to component supply tanks, preferably disposable tanks, in a known manner. When a nozzle assembly20is fully seated in the nozzle receiver assembly18, it is held in place by engagement with the latch claw92. Actuating the trigger24performs the steps necessary to discharge a foaming plastic product through the nozzle outlet42. The foam components are kept separate from each other during flow through the flow control valve housing16and initially mix with each other in the nozzle assembly20, preferably in the premix chamber36. If work is to be discontinued for a time sufficient for the foaming products to react and “set up” in the nozzle mix chamber, the nozzle assembly20may be removed and replaced and the process begun again. The gun assembly10may be used with a number of nozzle assemblies20for several applications. The gun assembly10is sufficiently economical that it can be discarded after the contents of the tanks are emptied although it can be easily cleaned and rebuilt, if desired, at minimal cost without the use of skilled labor.

Referring toFIG. 7, a dispensing gun assembly according to a second embodiment of the present invention, generally designated200, is shown to preferably include a gun body212having a handle214, a flow control valve housing216, a nozzle receiver assembly218(FIG. 8A), a removable nozzle assembly220, a nozzle latch assembly222, and a trigger member224. It is to be understood that the dispensing gun assembly200preferably includes a trigger safety (not shown) and hose connector fittings for first and second component inlet hoses as described above for the dispensing gun assembly10. A primary difference between the dispensing gun assembly200from the dispensing gun assembly10is the arrangement and operation of the valves which will be explained below.

Referring toFIGS. 7 and 8A, the upper portion of the gun body212includes the flow control valve housing216. The flow control valve housing216includes a pair of valve receiving bores262and263extending transversely to the principal axis of the housing216as shown inFIG. 10. The control valve housing216also includes a pair of product flow passageways264(FIG. 8A) extending axially through the housing216. While only one of the product flow passageways264is shown, it is to be understood that the second passageway is preferably identical to the passageway264shown and similar to the product flow passages64and66for the dispensing gun assembly10as shown inFIG. 4.

Referring toFIGS. 7,8A and10, first and second piston valves300and302, respectively, have a cylindrical body304with a pair of circumferential recesses306, each adapted to receive a seal308, preferably an O-ring seal. The body304includes a transverse fluid port310extending therethrough. An ear312extends from one end of the cylindrical body304. Preferably, the ear312is on the principal axis of the cylindrical body304. The ear312includes an end surface318adapted to contact an engagement surface320of the trigger member224. The trigger member224is preferably pivotally connected to the gun body212about a pivot point224p. Although not shown, it is to be understood that the dispensing gun assembly200preferably includes a trigger return spring as described above for the dispensing gun assembly10.

As shown inFIGS. 7,8A,8B and10, a return spring311, preferably a helical spring, is positioned in each valve receiving bore262,263between a cap screw313and the respective piston valve300,302. Preferably, each cap screw313includes a stop member315extending at a lower end of the cap screw313for reasons which will be explained below.

Referring toFIGS. 7 and 9, the nozzle latch assembly222includes a latch and ejector member274pivotally connected via a pin284to a forward portion of the housing216. The latch/ejector member274includes a claw292and an ejector leg290. The claw292and ejector leg290function in the same manner as claw92and ejector leg90of the latch/ejector member74of the first embodiment.

When the trigger224and the valves300and302are in their closed position as shown inFIGS. 7 and 8A, the return springs311apply a spring force against the upper end of the piston valves300and302causing the valves300and302to assume their closed, lowermost position within the valve receiving bores262and263. In the closed position, the fluid ports310of the valves300and302are out of registry with the valve seal ports326of the valve seals322. Additionally, the fluid ports310are preferably out of registry with the outlet passages245and247(seeFIGS. 8A and 9). It is to be understood that the closed position shown inFIG. 8Athe cylindrical body304of the valves300and302is in sealing engagement with an arcuate surface (now shown) of the valve seals322and also in sealing engagement with the valve receiving bore262. As described in the previous embodiment, preferably spring-type washers334exert an axial force on the valve seals322in the direction of the valves300and302.

With reference toFIGS. 8A and 10, the return springs311surround the stop members315to ensure that the return springs311remain axially oriented within the valve receiving bores262and263. Preferably, the cap screws313threadably engage the upper end of the valve receiving bores262and263. The lower or opposite end of the bores262and263include an aperture265adapted to receive the ears312of the valves300and302. Preferably, the ears312and the apertures265are sized to allow sliding movement of the ears312in the apertures265. Preferably, the apertures substantially restrict angular rotation of the valves300and302within the valve receiving bores262and263to maintain substantially parallel alignment of the fluid ports310with the valve seal ports326and outlet passages245and247.

Referring toFIG. 8B, upon “squeezing” the trigger224, the trigger224forces the valves300and302to their open or uppermost position in which the fluid ports310are substantially axially aligned with the valve seal ports326and the outlet passages245and247. In the open position, the return springs311are compressed and the valves300and302abut the lower end of the stop members315. The stop members315ensure the proper axial positioning of the valves300and302in the valve receiving bores262and263in the open position.

Upon release of the trigger224, the return springs311force the valves300and302to the closed position. It is to be understood that the return springs311could alternatively be located exteriorly of the valve receiving bores262and263. For example, the valve ears312could be connected to the trigger224and one or more return springs positioned between the trigger and the gun body212or between the trigger224and the flow control valve housing216.

While the advantages of the invention may be achieved and practiced by the use of other embodiments, the preferred embodiments of the invention are of the type shown, wherein the gun assembly is made principally from plastic material and includes the various structural and functional features described in detail.