US20020139818A1

US20020139818A1 - Snuffback-diversion flow valve system

Info

Publication number: US20020139818A1
Application number: US09/821,476
Authority: US
Inventors: Grant McGuffey
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 2001-03-29
Filing date: 2001-03-29
Publication date: 2002-10-03

Abstract

A valve assembly, for use in connection with the dispensing of hot melt adhesive material, comprises a snuffback valve member and a diversion flow valve member. The snuffback valve and diversion flow valve members are integrally connected together and are movable in opposite modes with respect to their valve seats such that when the snuffback valve member is seated upon its valve seat, the diversion flow valve member is unseated with respect to its valve seat, and vice versa. A recirculation fluid supply loop is fluidically associated with the diversion flow valve member, and when the diversion flow valve member is disposed at its unseated position, the hot melt adhesive material is recirculated so as not to pressurize the supply side of the snuffback valve member. Accordingly, when the snuffback valve member is unseated, the phenomena of bursting is effectively prevented. The geometries of the valve members and their valve seats are also predeterminedly related such that a neutral or negative pressure differential is created upon closure of the snuffback valve member and opening of the diversion flow valve member so as to prevent the occurrence of stringing.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This patent application is related to U.S. patent application Ser. No. 09/550,884 which was filed on Apr. 17, 2000.[0001]

FIELD OF THE INVENTION

The present invention relates generally to hot melt adhesive dispensing systems, and more particularly to a new and improved combination snuffback-diversion flow valve system for dispensing hot melt adhesive whereby inconsistent dispensing of the hot melt adhesive, characteristically present upon the commencement of a hot melt adhesive dispensing operation or cycle, is essentially eliminated, and in addition, quick shutoff, and proper pressure and volumetric control, of the adhesive supply internally within the valve assembly is able to be achieved at the termination of a hot melt adhesive dispensing operation or cycle, and particularly during closure of the snuffback valve, such that undesirable stringing of the adhesive does not occur.

BACKGROUND OF THE INVENTION

In connection with the dispensing of highly-viscous materials, such as, for example, hot melt adhesives, it is imperative that the dispensing system comprise what is known in the art as a snuffback valve by means of which the shutoff or termination of the dispensed adhesive is readily achieved upon closure of the valve whereby stringing of the adhesive does not occur. As disclosed within the aforenoted previously filed patent application, U.S. patent application Ser. No. 09/550,884, prior art snuffback valves, while certainly being capable of substantially performing their basic operations of controlling and preventing the dispensing of hot melt adhesives, nevertheless suffered several operational drawbacks or disadvantages, such as, for example, being relatively slow-acting, and permitting the aforenoted undesirable stringing of the hot melt adhesive materials upon termination of a hot melt adhesive dispensing cycle. In addition, due to the particular structural characteristics of such conventional or prior art snuffback valves, the dispensing systems would also experience or exhibit a phenomenon known as bursting wherein, upon commencement of a new adhesive dispensing operation or cycle, a sudden expulsion, discharge, or dispensing of a predetermined amount or glob of adhesive would occur.

Accordingly, by means of the particularly new and novel structure of the snuffback valve as disclosed within the aforenoted previously filed patent application, the aforenoted operational problems, drawbacks, and disadvantages characteristic of the conventional or prior art snuffback valves have been addressed and have been substantially reduced or rectified. However, it has been determined still further that some of the problems characteristic of the prior art snuffback valves, such as, for example, bursting and stringing, nevertheless persist within current hot melt adhesive dispensing systems despite the structural improvements, modifications, and refinements made to the snuffback valves in accordance with the principles and teachings of the invention embodiments as disclosed within the previously filed patent application, U.S. patent application Ser. No. 09/550,884. The reason for this is that the problems or operational drawbacks or disadvantages are no longer based or founded upon structural characteristics of the snuffback valve per se, but to the contrary, are believed to be based upon, or caused by, pressure and volumetric parameters characteristic of the hot melt adhesive dispensing system.

Accordingly, a need exists in the art for a new and improved snuffback valve control mechanism or assembly, for use in connection with hot melt adhesive dispensing systems, wherein the pressure and volumetric parameters can be advantageously predetermined and controlled such that the valve mechanism is rendered relatively fast-acting, and wherein further, bursting and stringing of the hot melt adhesive materials, upon commencement and termination of a particular hot melt adhesive dispensing operation or cycle, are respectively prevented or significantly reduced. In addition, it is required that the snuffback valve control mechanism or assembly, for achieving the aforenoted operational characteristics, be relatively simple in structure.

OBJECTS OF THE INVENTION

Accordingly, it is an object of the present invention to provide a new and improved snuffback valve control mechanism or assembly.

Another object of the present invention is to provide a new and improved snuffback valve control mechanism or assembly which overcomes the various operational drawbacks and disadvantages characteristic of prior art snuffback valve mechanisms.

An additional object of the present invention is to provide a new and improved snuffback valve control mechanism or assembly which overcomes the various operational drawbacks and disadvantages characteristic of prior art snuffback valve mechanisms whereby undesirable bursting and stringing is effectively prevented or significantly reduced.

A further object of the present invention is to provide a new and improved snuffback valve control mechanism or assembly which overcomes various operational drawbacks and disadvantages characteristic of prior art snuffback valve mechanisms, and which is simple in structure and relatively fast-acting whereby undesirable bursting and stringing is effectively prevented or significantly reduced.

A last object of the present invention is to provide a new and improved snuffback valve control mechanism or assembly which overcomes various operational drawbacks and disadvantages characteristic of prior art snuffback valve mechanisms, and which is simple in structure, whereby the snuffback valve control mechanism or assembly optimally controls pressure and volumetric parameters such that the snuffback valve control mechanism or assembly is relatively fast-acting and is able to effectively prevent or significantly reduce undesirable bursting and stringing.

SUMMARY OF THE INVENTION

The foregoing and other objectives are achieved in accordance with the teachings and principles of the present invention through the provision of a new and improved snuffback valve control mechanism or assembly which comprises a snuffback valve member and a diversion flow valve member wherein the two valve members are integrally connected together. A valve seat member is provided with first and second valve seats upon which the snuffback valve member and the diversion flow valve member are adapted to be respectively seated in such a manner that when a first one of the snuffback valve member and the diversion flow valve member is seated upon its valve seat, the other one of the snuffback valve member and the diversion flow valve member is unseated with respect to it valve seat. An adhesive supply port and an adhesive return port are fluidically connected to the valve seat member in such a manner that when the snuffback valve member is seated upon its valve seat, that is, when the snuffback valve member is closed such that no adhesive material is being dispensed, and the diversion flow valve member is unseated with respect to its valve seat, adhesive material is simply in effect recirculated in a closed loop manner from an adhesive supply tank, through the adhesive supply port, through the valve seat member, past the diversion flow valve member, and through the adhesive return port so as to be returned and recirculated back to the adhesive supply tank. Accordingly, zero pressure is effectively applied to the supply side of the snuffback valve member, or considered alternatively, excessive pressure which would normally be impressed upon the supply side of the snuffback valve member is in effect relieved, such that a large amount of pressure is not fluidically impressed upon or built up within the adhesive material upon the supply side of the snuffback valve member. Therefore, when the snuffback valve member is unseated from its valve seat so as to be opened and permit dispensing of the adhesive material, the absence of any excessive pressure upon the supply side of the snuffback valve member effectively prevents the phenomenon of bursting from occurring.

In addition, when the dispensing operation or cycle is terminated, the snuffback valve is moved from its opened, unseated position with respect to its valve seat to its closed, seated position with respect to its valve seat while the diversion flow valve member is simultaneously moved from its closed, seated position with respect to its valve seat to its opened, unseated position with respect to its valve seat. The volumetric geometry of the valve seat portion of the diversion flow valve member is also made substantially equal to, or alternatively greater than, the volumetric geometry of the valve seat portion of the snuffback valve member such that when the snuffback valve member is closed and seated upon its valve seat while the diversion flow valve member is simultaneously opened and unseated with respect to its valve seat, a zero pressure change, or alternatively, a negative pressure change, is induced within the adhesive material being conducted through the valve seat member, past the diversion flow valve member, and back to the adhesive supply tank, whereby zero pressure, or alternatively, negative pressure, is likewise induced within the adhesive material disposed upon the supply side of the snuffback valve member such that the adhesive material is in effect drawn backwardly toward the snuffback valve member valve seat in the direction which is opposite to the direction in which the adhesive material is normally discharged or dispensed from the valve assembly whereby stringing of the adhesive material is effectively prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, features, and attendant advantages of the present invention will be more fully appreciated from the following detailed description when considered in connection with the accompanying drawings in which like reference characters designate like or corresponding parts throughout the several views, and wherein: [0013]
FIG. 1 is a cross-sectional view of a new and improved snuffback valve control mechanism or assembly constructed in accordance with the principles and teachings of the present invention and which discloses the snuffback valve member and diversion flow valve member integrally connected together; and [0014]
FIG. 2 is a view, similar to that of FIG. 1, partially showing, however, the new and improved snuffback valve control mechanism or assembly in enlarged and greater detail.[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, and more particularly to FIGS. 1 and 2 thereof, a new and improved snuffback valve control mechanism or assembly constructed in accordance with the principles and teachings of the present invention is disclosed and is generally indicated by the [0016] reference character 10. As can be seen from the drawing figures, the snuffback valve control mechanism or assembly 10 comprises a valve body 12 within which there is fixedly mounted an annular or tubular valve seat member 14, and a first valve seat portion 16 is defined upon a lower end portion of the valve seat member 14. A snuffback valve element 18 is movably disposed or mounted within a lower discharge cavity or cylindrical chamber 20 formed within a lower section of the valve body 12 so as to control the discharge or dispensing of, for example, hot melt adhesive material from an outlet 22 which is defined within a lowermost end portion of the valve body 12, and the upper end portion of the snuffback valve element 18 is provided with a valve seat engagement portion 24 which, as will be discussed more fully hereinafter, is provided with a predeterminedly unique geometrical and volumetric structure so as to properly cooperate with the first valve seat portion 16 of the valve seat member 14. The snuffback valve element 18 further comprises an upwardly extending valve stem 26 which is internally movable in a vertically oriented axial direction within the tubular valve seat member 14, and in accordance with a first unique and novel structural arrangement or characteristic developed in accordance with the principles and teachings of the present invention, the snuff-back valve control mechanism or assembly 10 is seen to further comprise a diversion flow valve member 28.
The diversion [0017] flow valve member 28 is provided with a blind bore 30 within the lower end portion thereof, and in this manner, the upper end portion of the snuffback valve stem 26 is able to be seated therein. The upper end portion of the snuffback valve stem 26 and the diversion flow valve member 28 are adapted to be integrally connected together, and accordingly, a suitable transversely disposed fastener, such as, for example, a rivet 32, passes through the upper end portion of the snuffback valve stem 26 and opposite sidewall portions the diversion flow valve member 28 so as to fixedly connect such components together. The upper end portion of the valve seat member 14 is provided with a second valve seat portion 34, and the lowermost end portion of the diversion flow valve member 28, in a manner similar to that of the valve seat engagement portion 24 formed upon the snuffback valve element 18, is provided with a valve seat engagement portion 36 which has a predeterminedly unique geometrical and volumetric structure so as to properly cooperate with the second valve seat portion 34 of the valve seat member 14.
In accordance with a second unique and novel structural arrangement or characteristic developed in accordance with the principles and teachings of the present invention, the snuff-back valve control mechanism or [0018] assembly 10 is seen to further comprise, or have operatively associated therewith, an endless recirculation loop for the supply of the hot melt adhesive material with respect to the valve body 12 and the snuffback valve element 18, the significance of which will be discussed shortly hereafter. More particularly, as schematically illustrated, the hot melt adhesive material is contained within a supply tank T, and a pump P delivers the hot melt adhesive material from the supply tank T to a first hot melt adhesive supply port 38 defined within the valve body 12 by means of a first fluid conduit 40. The valve body 12 likewise comprises a second hot melt adhesive return port 42 by means of which hot melt adhesive material is transmitted or conducted from the valve body 12 back to the adhesive material supply tank T by means of a second fluid conduit 44. The valve seat member 14 is fixedly mounted within or upon a lower end portion 46 of a seal cartridge 47, and the seal cartridge is, in turn, fixedly mounted within the valve body 12. The lower end portion 46 of the seal cartridge 47 is provided with a first inlet port 48 which is fluidically connected to the first hot melt adhesive supply port 38 formed within the valve body 12, and the upper end portion of the valve seat member 14 is provided with a plurality of circumferentially spaced through-bores 50 which are adapted to be fluidically connected to the inlet port 48. A lower end portion 52 of the valve seat member 14 is annularly spaced with respect to the snuffback valve stem 26 such that an annular, axially extending fluid passageway 54 is defined therebetween, and in this manner, hot melt adhesive material is able to be conveyed toward the snuffback valve element 18, particularly when the snuffback valve element 18 has been unseated from its valve seat 16, such that the hot melt adhesive material can then be discharged or dispensed from the outlet 22 of the valve assembly 10 after having passed through an annular space 55 defined between the outer peripheral surface of the snuffback valve element 18 and the interior peripheral wall surface of the lower discharge cavity or cylindrical chamber 20 of valve body 12. Continuing further, an intermediate portion of the seal cartridge 47 is likewise provided with a second outlet port 56 which is adapted to be fluidically connected to the second hot melt adhesive return port 42 defined within the valve body 12.
It is thus to be appreciated and particularly emphasized that, in accordance with the unique and novel structure characteristic of the snuffback valve control mechanism or [0019] assembly 10 constructed and developed in accordance with the principles and teachings of the present invention, when the various components of the new and improved snuffback valve control mechanism or assembly 10 are disposed at or in their respective positions or states as illustrated in the drawing FIGS. 1-2, wherein the snuff-back valve element 18 is disposed at its raised position so as to be seated upon its valve seat 16, while the diversion flow valve member 28 is likewise disposed at its raised position so as to be unseated with respect to its valve seat 34, the hot melt adhesive material will not be discharged or dispensed, and more importantly with respect to the objectives, purposes, and aims of the present invention, the hot melt adhesive material will simply be recirculated. More particularly, the hot melt adhesive material, supplied to the valve body 12 from the supply tank T by means of the pump P, will be recirculated within the endless loop defined by means of the first fluid conduit 40, valve body supply port 38, seal cartridge inlet port 48, through diversion flow valve member valve seat 34, seal cartridge outlet port 56, valve body return port 42, and second fluid conduit 44. Consequently, as a result of such recirculation of the hot melt adhesive material within the endless loop path as just noted, substantially zero pressure is applied to or impressed upon the supply side of the snuffback valve element 18, or considered alternatively, an excessive amount of pressure is not built up or impressed upon the supply side of the snuffback valve element 18, or considered still yet alternatively, the excessive amount of pressure which would normally or conventionally be built up, accumulated, or impressed upon the supply side of the snuffback valve element 18, such excessive pressure is effectively relieved as a result of the aforenoted recirculation of the hot melt adhesive material.
Accordingly, when the [0020] snuffback valve element 18 is moved from the illustrated closed and seated position to the opened and unseated position with respect to its valve seat 16 so as to permit the hot melt adhesive material to in fact be discharged or dispensed, the absence of the excessive pressure with respect to the supply side of the snuffback element 18 permits the hot melt adhesive material to now be dispensed or discharged under normal pressure parameters as determined, for example, by means of pump P, whereby the phenomenon of bursting, comprising an excessive of amount of hot melt adhesive being initially expressed, discharged, or dispensed from the valve outlet 22, is effectively prevented. In addition, and in conjunction with this operational state of the valve assembly 10, a further operational benefit is also achieved, by means of the aforenoted unique and novel structure of the snuffback valve control mechanism or assembly 10 constructed and developed in accordance with the principles and teachings of the present invention. More particularly, as a result of the elimination of, or the substantial reduction in, the pressure level upon the supply side of the snuffback valve element 18, the opening operation of the snuffback valve control mechanism or assembly 10, or in other words, the transitional time required between the closed and opened states of the snuffback valve element 18, is rendered quicker or faster. The reason for this may be appreciated as a result of further reference being made to FIGS. 1 and 2.
As can be further seen from FIGS. 1 and 2, in order to achieve actuation of the [0021] snuffback valve element 18 with respect to its valve seat 16, as well as the actuation of diversion flow valve member 28 with respect to its valve seat 34, diversion flow valve member 28 is provided with an upstanding valve stem 58 which is linearly movable through an axially oriented bore 60 defined within the seal cartridge 47 and which is fixedly connected at its upper end portion to a piston member 62. The piston member 62 is reciprocably disposed within a cylinder chamber 64, and in order to achieve the reciprocal movement of the piston member 62, and therefore the linear axial upward and downward movements of the diversion flow valve member 28 and the snuffback valve element 18, the valve body 12 is provided with a first CLOSE control air port 66 and a second OPEN control air port 68. The CLOSE control air port 66 is fluidically connected to a vertical fluid passageway 70 defined within an upper end portion of the valve body 12, and an additional vertically oriented fluid passageway 72 is defined by means of a through-bore provided within a head portion 74 of the seal cartridge 47. The upper end of fluid passageway 72 is, in turn, fluidically connected to the lower end portion of the cylinder chamber 64, and in this manner, the CLOSE control air introduced through means of CLOSE control air port 66 can impinge upon the underside or undersurface portion 76 of the piston member 62. Accordingly, when CLOSE control air impinges upon the undersurface portion 76 of the piston member 62, the piston member 62 is caused to move upwardly within cylinder chamber 64 whereby the upward movement of diversion flow valve stem 58 causes diversion flow valve member 28, and snuffback valve element 18 integrally connected thereto, to be moved to their respective raised positions at which the snuffback valve element 18 is seated upon its valve seat 16 while the diversion flow valve member 28 is unseated with respect to its valve seat 34.
In a similar manner, the OPEN [0022] control air port 68 is fluidically connected to the upper end portion of the cylinder chamber 64, and in this manner, the OPEN control air is able to impinge upon the upper surface portion 78 of the piston member 62. Accordingly, when OPEN control air impinges upon the upper surface portion 78 of the piston member 62, the piston member 62 will be moved downwardly within cylinder chamber 64 whereby the downward movement of the diversion flow valve stem 58 will cause diversion flow valve member 28 and snuffback valve element 18 to be moved to their respective lowered positions at which snuffback valve element 18 is unseated from its valve seat 16 while diversion flow valve member 28 is seated upon its valve seat 34.
Accordingly, since it is to be remembered that, when [0023] snuffback valve element 18 is seated upon its valve seat 16 such that snuffback valve element 18, and snuffback valve assembly 10, are closed whereby hot melt adhesive material is not dispensed or discharged from assembly outlet 22, the hot melt adhesive material is recirculated within its endless supply loop and that the pressure impressed upon the supply side of snuffback valve element 18 is therefore substantially zero, it is apparent that less air pressure is required to be admitted into the air control system through means of CLOSE control air port 66 in order to maintain piston member 62 at its elevated position so as to in turn maintain snuffback valve element 18 at its closed and seated position with respect to its valve seat 16. Consequently, when OPEN control air is admitted into the air control system through means of OPEN control air port 68 in order to move snuffback valve element 18 to its open and unseated position with respect to its valve seat 16, less air will be required to be exhausted through means of the CLOSE air control port 66 whereby the time required to open the snuffback valve element 18 from its closed and seated state is significantly reduced.
A last unique and novel feature or characteristic of the new and improved snuffback valve control mechanism or [0024] assembly 10, constructed and developed in accordance with the principles and teachings of the present invention, resides in the fact that interrelated cooperative structure is provided within the snuffback valve control mechanism or assembly 10 whereby stringing of hot melt adhesive material, upon termination of a dispensing operation or cycle, is effectively prevented. One structural feature of the present invention which facilitates this result resides in the provision of the diversion flow valve member 28 in conjunction with the hot melt adhesive material recirculation loop comprising the hot melt adhesive material supply tank T, pump P, conduit 40, supply port 38, ports 48, 50, 56, return port 42, and conduit 44. As a result of such structure, and remembering that the snuffback valve element 18 and the diversion flow valve member 28 are integrally connected together so as to move in tandem and simultaneously with each other, when the snuffback valve element 18 is being moved from its opened unseated position toward its closed seated position with respect to its valve seat 16, hot melt adhesive material disposed upon the supply side of the snuffback valve element 18 will be moved or forced toward the valve seat 16. Therefore, if the diversion flow valve member 28 with its valve seat 34, and the aforenoted hot melt adhesive material recirculation loop were not provided, then the supply side of the snuffback valve element 18 would in effect be pressurized by means of hot melt adhesive material being supplied thereto from a supply source by means of a suitable pump. Accordingly, the snuffback valve element 18 would in effect have to be returned from its opened unseated position toward its closed seated position against the supply pressure of the hot melt adhesive material, and therefore hot melt adhesive material disposed upon the supply side of the snuffback valve element 18 will tend to flow back around the snuffback valve element 18 and through the annular passageway 55 toward the discharge outlet 22 thereby tending to develop stringing.
With the present invention, however, and in particticular, as a result of the provision of the diversion [0025] flow valve member 28 in conjunction with the hot melt adhesive material recirculation loop, the pressure upon the supply side of the snuffback valve element 18 is effectively relieved and the hot melt adhesive material disposed upon the supply side of the snuffback valve element 18 is able to be effectively forced backwardly through diversion flow valve member valve seat 34, port 56, and return port 42 into the recirculation loop which in turn also tends to draw any hot melt adhesive material disposed within valve body chamber 20 away from the discharge outlet 22. In order to facilitate this mode of operation still further, the geometries of the two valve seats 16 and 34 for the snuffback valve element 18 and the diversion flow valve member 28, as well as the geometries of the valve seat engagement portions 24, 36 of the snuffback valve element 18 and the diversion flow valve member 28, are made so as to be substantially the same, symmetrical, or equal whereby a neutral or zero pressure differential is developed within such fluid flows such that substantially equal volumes of hot melt adhesive material are conveyed through the respective valve seats. Alternatively, still further, the valve seat 34 and the valve seat engagement portion 36 of the diversion flow valve member 28 may have volumetric geometry values which are larger than those of the valve seat 16 and the valve seat engagement portion 24 of the snuffback valve element 18. In this manner, a negative pressure differential is created between the hot melt adhesive material flows within the regions of the valve seats 16, 34 of the snuffback valve element 18 and the diversion flow valve member 28 whereby the flow of hot melt adhesive material away from the valve assembly outlet or discharge port 22 is enhanced still further.
Thus, it may be seen that in accordance with the principles and teachings of the present invention, there has been provided a new and improved snuff-back valve control mechanism or assembly which comprises, in conjunction with the snuffback valve element, a diversion flow valve member and a hot melt adhesive recirculation loop. As a result of the provision of the diversion flow valve member and the hot melt adhesive recirculation loop, the hot melt adhesive material is able to be simply recirculated when the snuffback valve element is disposed at its closed, seated position such that pressurized hot melt adhesive material is not applied to the supply side of the snuffback valve element. In this manner, when the snuffback valve element is then moved to its opened, unseated position, there is no excessive pressure impressed upon the hot melt adhesive material which would otherwise result in the sudden expulsion or bursting of hot melt adhesive material during the initial stage of a discharge or dispensing operation or cycle. In addition, the system enables the snuffback valve element to open faster, and still yet further, the provision of the diversion flow valve member and the recirculation loop, as well as advantageous geometrical parameters of the snuffback valve and diversion flow valve seats effectively prevent the occurrence of stringing upon termination of a hot melt adhesive material dispensing operation or cycle. [0026]
Obviously, many variations and modifications of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein. [0027]

Claims

What is claimed as new and desired to be protected by Letters Patent of the United States of America, is:

1. A valve assembly for use in connection with the dispensing of fluid materials, comprising:

a housing;

a supply port defined upon said housing for introducing materials, to be dispensed, into said housing;

an exit port defined upon said housing for permitting materials to be conducted out of said housing;

a discharge outlet defined upon said housing for permitting materials to be dispensed from said valve assembly;

a first valve seat;

a first valve member movably disposed within said housing between a first position at which said first valve member is seated upon said first valve seat so as to prevent materials from being dispensed from said valve assembly through said discharge outlet, and a second position at which said first valve member is unseated with respect to said first valve seat so as to permit materials to be dispensed from said valve assembly through said discharge outlet;

a second valve seat; and

a second valve member fixedly connected to said first valve member so as to be movably disposed within said housing, and in conjunction with said first valve member, between a first position at which said second valve member is unseated with respect to said second valve seat when said first valve member is seated upon said first valve seat so as to permit materials to be conducted from said supply port to said exit port and not pressurize said first valve member seated upon said first valve seat, and a second position at which said second valve member is seated upon said second valve seat when said first valve member is unseated with respect to said first valve seat so as to prevent materials from being conducted from said supply port to said exit port and to permit materials to be conducted toward said discharge outlet so as to be dispensed from said valve assembly through said discharge outlet in a substantially consistent manner, without exhibiting bursting phenomena, throughout dispensing operation cycles.

2. The valve assembly as set forth in claim 1, further comprising:

a material supply tank fludically connected to said exit port by means of a first fluid conduit;

a pump fluidically connected to said material supply tank by means of a second fluid conduit, and fluidically connected to said supply port by means of a third fluid conduit,

wherein said exit port, said first fluid conduit, said material supply tank, said second fluid conduit, said pump, said third fluid conduit, and said supply port define a recirculation loop with respect to said housing for the materials to be dispensed.

3. The valve assembly as set forth in claim 1, wherein:

said first valve member comprises a first valve stem; and

said second valve member has a recess defined therein within which an end portion of said first valve stem of said first valve member is fixedly disposed so as to integrally connect said first and second valve members together.

4. The valve assembly as set forth in claim 3, further comprising:

a cylinder chamber defined within said housing; and

a piston movably disposed within said cylinder chamber;

said second valve member comprising a second valve stem fixedly connected to said piston such that upon movement of said piston within said cylinder chamber, said first valve member is moved along with said second valve member as a result of said first valve stem of said first valve member being connected to said second valve member, and as a result of said second valve stem of said second valve member being connected to said piston.

5. The valve assembly as set forth in claim 4, further comprising:

a CLOSE air port defined within said housing for introducing CLOSE air into said housing so as to impinge upon a first surface of said piston whereby said piston causes said first valve member to move to said first seated position with respect to said first valve seat; and

an OPEN air port defined within said housing for introducing OPEN air into said housing so as to impinge upon a second surface of said piston whereby said piston causes said first valve member to move said second unseated position with respect to said first valve seat.

6. A valve assembly for use in connection with the dispensing of highly viscous materials, comprising:

a housing;

a supply port defined upon said housing for introducing highly viscous materials, to be dispensed, into said housing;

an exit port defined upon said housing for permitting highly viscous materials to be conducted out of said housing;

a discharge outlet defined upon said housing for permitting highly viscous materials to be dispensed from said valve assembly;

a first valve seat;

a first valve member movably disposed within said housing between a first position at which said first valve member is seated upon said first valve seat so as to prevent highly viscous materials from being dispensed from said valve assembly through said discharge outlet, and a second position at which said first valve member is unseated with respect to said first valve seat so as to permit highly viscous materials to be dispensed from said valve assembly through said discharge outlet;

a second valve seat; and

a second valve member fixedly connected to said first valve member so as to be movably disposed within said housing, and in conjunction with said first valve member, between a first position at which said second valve member is unseated with respect to said second valve seat when said first valve member is seated upon said first valve seat so as to permit highly viscous materials to be conducted from said supply port to said exit port and not pressurize said first valve member seated upon said first valve seat, and a second position at which said second valve member is seated upon said second valve seat when said first valve member is unseated with respect to said first valve seat so as to prevent highly viscous materials from being conducted from said supply port to said exit port and to permit highly viscous materials to be conducted toward said discharge outlet so as to be dispensed from said valve assembly through said discharge outlet in a substantially consistent manner, without exhibiting bursting phenomena, throughout dispensing operation cycles.

7. The valve assembly as set forth in claim 6, further comprising:

wherein said exit port, said first fluid conduit, said material supply tank, said second fluid conduit, said pump, said third fluid conduit, and said supply port define a recirculation loop with respect to said housing for the highly viscous materials to be dispensed.

8. The valve assembly as set forth in claim 6, wherein:

said first valve member comprises a first valve stem; and

9. The valve assembly as set forth in claim 8, further comprising:

a cylinder chamber defined within said housing; and

a piston movably disposed within said cylinder chamber;

10. The valve assembly as set forth in claim 4, further comprising:

11. A valve assembly for use in connection with the dispensing of highly viscous materials, comprising:

a housing;

a first valve seat;

a first snuffback valve member movably disposed within said housing between a first position at which said first snuffback valve member is seated upon said first valve seat so as to prevent highly viscous materials from being dispensed from said valve assembly through said discharge outlet, and a second position at which said first snuffback valve member is unseated with respect to said first valve seat so as to permit highly viscous materials to be dispensed from said valve assembly through said discharge outlet;

a second valve seat; and

a second diversion flow valve member fixedly connected to said first valve member so as to be movably disposed within said housing, and in conjunction with said first snuffback valve member, between a first position at which said second diversion flow valve member is unseated with respect to said second valve seat when said first valve member is seated upon said first valve seat so as to permit highly viscous materials to be conducted from said supply port to said exit port and not pressurize said first snuffback valve member seated upon said first valve seat, and a second position at which said second diversion flow valve member is seated upon said second valve seat when said first snuffback valve member is unseated with respect to said first valve seat so as to prevent highly viscous materials from being conducted from said supply port to said exit port and to permit highly viscous materials to be conducted toward said discharge outlet so as to be dispensed from said valve assembly through said discharge outlet in a substantially consistent manner, without exhibiting bursting phenomena, throughout dispensing operation cycles.

12. The valve assembly as set forth in claim 11, further comprising:

a highly viscous material supply tank fludically connected to said exit port by means of a first fluid conduit;

a pump fluidically connected to said highly viscous material supply tank by means of a second fluid conduit, and fluidically connected to said supply port by means of a third fluid conduit,

wherein said exit port, said first fluid conduit, said highly viscous material supply tank, said second fluid conduit, said pump, said third fluid conduit, and said supply port define a recirculation loop with respect to said housing for the highly viscous material to be dispensed.

13. The valve assembly as set forth in claim 11, wherein:

said first snuffback valve member comprises a first valve stem; and

said second diversion flow valve member has a recess defined therein within which an end portion of said first valve stem of said first snuffback valve member is fixedly disposed so as to integrally connect said first snuffback and second diversion flow valve members together.

14. The valve assembly as set forth in claim 13, further comprising:

a cylinder chamber defined within said housing; and

a piston movably disposed within said cylinder chamber;

said second diversion flow valve member comprising a second valve stem fixedly connected to said piston such that upon movement of said piston within said cylinder chamber, said first snuffback valve member is moved along with said second diversion flow valve member as a result of said first valve stem of said first snuffback valve member being connected to said second diversion flow valve member, and as a result of said second valve stem of said second diversion flow valve member being connected to said piston.

15. The valve assembly as set forth in claim 14, further comprising:

an OPEN air port defined within said housing for introducing OPEN air into said housing so as to impinge upon a first surface of said piston whereby said piston causes said first snuffback valve member to move said second unseated position with respect to said first valve seat; and

a CLOSE air port defined within said housing for introducing CLOSE air into said housing so as to impinge upon a second surface of said piston whereby said piston causes said first snuffback valve member to move to said first seated position upon said first valve seat while said second diversion flow valve member is moved to said first unseated position with respect to said second valve seat.

16. The valve assembly as set forth in claim 15, wherein:

said first snuffback valve member comprises a first valve seat engagement portion having a first predetermined structural geometry for engaging said first valve seat which has a predetermined structural geometry corresponding to said first predetermined structural geometry of said first valve seat engagement portion; and

said second diversion flow valve member comprises a second valve seat engagement portion having a second predetermined structural geometry for engaging said second valve seat which has a predetermined structural geometry corresponding to said second predetermined structural geometry of said second valve seat engagement portion;

said structural geometries of said first and second valve seat engagement portions and said first and second valve seats being substantially equal such that when said first snuffback valve member is moved toward said first valve seat so as to be seated upon said first valve seat, and said second diversion flow valve member is moved away from said second valve seat so as to be unseated with respect to said second valve seat, a zero pressure differential is developed within the highly viscous material being dispensed such that reverse flow of the highly viscous material being dispensed back toward said discharge outlet is effectively prevented so as to in turn effectively prevent the phenomena of stringing from occurring upon termination of a highly viscous material dispensing operation cycle.

17. The valve assembly as set forth in claim 15, wherein:

said structural geometries of said second valve seat engagement portion and said second valve seat being greater than said structural geometries of said first valve seat engagement portion and said first valve seat such that when said first snuffback valve member is moved toward said first valve seat so as to be seated upon said first valve seat, and said second diversion flow valve member is moved away from said second valve seat so as to be unseated with respect to said second valve seat, a negative pressure differential is developed within the highly viscous material being dispensed such that reverse flow of the highly viscous material being dispensed back toward said discharge outlet is effectively prevented so as to in turn effectively prevent the phenomena of stringing from occurring upon termination of a highly viscous material dispensing operation cycle.

18. A valve assembly for use in connection with the dispensing of hot melt adhesive material, comprising:

a housing;

a supply port defined upon said housing for introducing hot melt adhesive material, to be dispensed, into said housing;

an exit port defined upon said housing for permitting hot melt adhesive material to be conducted out of said housing;

a discharge outlet defined upon said housing for permitting hot melt adhesive material to be dispensed from said valve assembly;

a first valve seat;

a first snuffback valve member movably disposed within said housing between a first position at which said first snuffback valve member is seated upon said first valve seat so as to prevent hot melt adhesive material from being dispensed from said valve assembly through said discharge outlet, and a second position at which said first snuffback valve member is unseated with respect to said first valve seat so as to permit hot melt adhesive material to be dispensed from said valve assembly through said discharge outlet;

a second valve seat; and

a second diversion flow valve member fixedly connected to said first valve member so as to be movably disposed within said housing, and in conjunction with said first snuffback valve member, between a first position at which said second diversion flow valve member is unseated with respect to said second valve seat when said first valve member is seated upon said first valve seat so as to permit hot melt adhesive material to be conducted from said supply port to said exit port and not pressurize said first snuffback valve member seated upon said first valve seat, and a second position at which said second diversion flow valve member is seated upon said second valve seat when said first snuffback valve member is unseated with respect to said first valve seat so as to prevent hot melt adhesive material from being conducted from said supply port to said exit port and to permit hot melt adhesive material to be conducted toward said discharge outlet so as to be dispensed from said valve assembly through said discharge outlet in a substantially consistent manner, without exhibiting bursting phenomena, throughout dispensing operation cycles.

19. The valve assembly as set forth in claim 18, further comprising:

a hot melt adhesive material supply tank fludically connected to said exit port by means of a first fluid conduit;

a pump fluidically connected to said hot melt adhesive material supply tank by means of a second fluid conduit, and fluidically connected to said supply port by means of a third fluid conduit,

wherein said exit port, said first fluid conduit, said hot melt adhesive material supply tank, said second fluid conduit, said pump, said third fluid conduit, and said supply port define a recirculation loop with respect to said housing for the hot melt adhesive material to be dispensed.

20. The valve assembly as set forth in claim 18, wherein:

said first snuffback valve member comprises a first valve stem; and

21. The valve assembly as set forth in claim 20, further comprising:

a cylinder chamber defined within said housing; and

a piston movably disposed within said cylinder chamber;

22. The valve assembly as set forth in claim 21, further comprising:

23. The valve assembly as set forth in claim 22, wherein:

said structural geometries of said first and second valve seat engagement portions and said first and second valve seats being substantially equal such that when said first snuffback valve member is moved toward said first valve seat so as to be seated upon said first valve seat, and said second diversion flow valve member is moved away from said second valve seat so as to be unseated with respect to said second valve seat, a zero pressure differential is developed within the hot melt adhesive material being dispensed such that reverse flow of the hot melt adhesive material being dispensed back toward said discharge outlet is effectively prevented so as to in turn effectively prevent the phenomena of stringing from occurring upon termination of a hot melt adhesive material dispensing operation cycle.

24. The valve assembly as set forth in claim 22, wherein:

said structural geometries of said second valve seat engagement portion and said second valve seat being greater than said structural geometries of said first valve seat engagement portion and said first valve seat such that when said first snuffback valve member is moved toward said first valve seat so as to be seated upon said first valve seat, and said second diversion flow valve member is moved away from said second valve seat so as to be unseated with respect to said second valve seat, a negative pressure differential is developed within the hot melt adhesive material being dispensed such that reverse flow of the hot melt adhesive material being dispensed back toward said discharge outlet is effectively prevented so as to in turn effectively prevent the phenomena of stringing from occurring upon termination of a hot melt adhesive material dispensing operation cycle.