Hot melt adhesive metering pump assembly with integral reservoir tank

A hot melt adhesive metering pump assembly, and an integral reservoir tank fluidically connected thereto and the hot melt adhesive metering pump assembly comprises a plurality of rotary, gear-type metering pumps which are arranged in a compact, longitudinally spaced manner upon a drive gear manifold. All of the driven gears of pumps are respectively driven by manifold pump drive gears which are rotatably mounted upon a common motor-driven rotary drive shaft rotatably disposed within the drive gear manifold, and a first side wall member of a base portion of the reservoir tank is integrally connected to a side wall portion of the drive gear manifold, while a second side wall member of the base portion of the reservoir tank is provided with a plurality of hose connections to which hot melt adhesive delivery hoses are to be connected so as to respectively convey the precisely metered amounts of the hot melt adhesive material toward the applicator heads.

FIELD OF THE INVENTION

The present invention relates generally to hot melt adhesive dispensing systems, and more particularly to a new and improved hot melt adhesive metering pump assembly, and an integral reservoir tank fluidically connected thereto, for supplying predetermined or precisely metered volumes of hot melt adhesive material toward applicator head or dispensing nozzle structures, wherein the integral reservoir tank effectively serves as a built-in adhesive supply unit (ASU), wherein the new and improved hot melt adhesive metering pump assembly comprises a plurality of rotary, gear-type metering pumps which are arranged in a compact, longitudinally spaced manner upon a drive gear manifold such that the rotational axes of the plurality of rotary, gear-type metering pumps are disposed parallel and adjacent to one side of the drive gear manifold, wherein all of the driven gears of the rotary, gear-type metering pumps are respectively driven by pump drive gears which are rotatably mounted upon a common motor-driven drive shaft, wherein a first side wall member of a base portion of the reservoir tank is integrally connected to a side wall portion of the drive gear manifold, and wherein a second side wall member of the base portion of the reservoir tank is provided with a plurality of hose connections to which hot melt adhesive delivery hoses are to be connected so as to respectively conduct or convey the precisely metered amounts of the hot melt adhesive material, outputted by means of the plurality of rotary, gear-type metering pumps mounted upon the drive gear manifold, toward the applicator heads or dispensing nozzles.

BACKGROUND OF THE INVENTION

In connection with liquid dispensing assemblies, and more particularly, in connection with liquid dispensing assemblies which are being used to dispense hot melt adhesives or other thermoplastic materials, a typical dispensing assembly conventionally comprises a supply source of the adhesive or thermoplastic material, and means for precisely or accurately metering and pumping the adhesive or thermoplastic material toward an applicator head or dispensing assembly. In connection with particular applications or procedures, it is necessary to accurately or precisely meter the liquids being dispensed so as to ensure that a specific or predetermined volume of the liquid is in fact dispensed within a specific or predetermined period of time. For example, in connection with the dispensing of hot melt adhesive materials, it is often necessary to provide a plurality of individual pumps for providing predetermined volumes of the adhesive material, which may in fact comprise similar or different volume quantities or amounts, to discrete, separate, or respective applicator or dispensing outlets. The individual pumps conventionally comprise rotary gear pumps which are operatively connected to a drive motor through means of a common rotary drive shaft, and dynamic seals, that is, stationary seals which are operatively disposed around or operatively associated with the rotary drive shaft, are provided for effectively preventing any external or outward leakage of the hot melt adhesive material from the assembly at the interfaces defined between the rotary drive shaft and the rotatably driven gears of the rotary gear pumps. An example of such a conventional or PRIOR ART hot melt adhesive rotary gear pump assembly is disclosed, for example, within U.S. Pat. No. 6,422,428 which issued to Allen et al. on Jul. 23, 2002.

More particularly, as disclosed withinFIG. 1, which corresponds substantially toFIG. 3of the aforenoted patent to Allen et al., one of a plurality of gear pump assemblies, as utilized within a hot melt adhesive applicator assembly, is disclosed at20, and it is seen that each gear pump assembly20comprises a conventional sandwiched construction comprising three plates220,222,224encompassing or enclosing a pair of gears230,232. Gear230comprises an idler gear, whereas gear232comprises a driven gear which is operatively mounted upon a rotary drive shaft234. The rotary drive shaft234has a hexagonal cross-sectional configuration so as to effectively define or provide the drive connection with the driven gear232, and it is noted that the drive shaft234extends through each one of the gear pump assemblies20. A pair of seals240, only one of which is shown inFIG. 1, are provided within suitable apertures defined within the end plates220,224so as to annularly surround the rotary drive shaft234and thereby prevent any leakage of the hot melt adhesive material out from the gear pump assembly20. A threaded port244is provided for receiving a temperature sensor for ensuring that each gear pump assembly20has been heated to a predetermined temperature level prior to operation, and a rupture disk assembly242is provided for pressure relief under overpressure conditions. A bore248is provided for receiving a pressure transducer which can read output liquid pressure, and when the pressure transducer is not being utilized, a plug assembly250is adapted to be disposed within the bore248.

While a gear pump assembly20such as that disclosed within the aforenoted patent to Allen et al. is operatively viable, the gear pump assembly20of the aforenoted type nevertheless exhibits several operative drawbacks and disadvantages. Firstly, for example, it is noted that in view of the fact that the seals240of the gear pump assembly20are located upon external surface portions of the end plates220,224of the gear pump assembly20, should the seals240experience failure, external leakage of the hot melt adhesive material poses obvious maintenance problems, not to mention the likelihood of the leaking hot melt adhesive material causing fouling of other operative components of the gear pump assembly20. In addition, it has been noted in the aforenoted patent to Allen et al. that the rotary drive shaft234extends through each one of the gear pump assemblies20. Accordingly, if, for example, one of the gear pump assemblies20should experience failure or exhibit leakage, and therefore needs to be removed for repair or replacement, the particular gear pump assembly20cannot in fact simply be removed from the overall hot melt adhesive dispensing assembly comprising the plurality of gear pump assemblies20. To the contrary, and more particularly, the rotary drive shaft234must firstly be removed so as to subsequently permit the particular gear pump assembly20to be removed and separated from the other gear pump assemblies20in order to repair or replace the failed or leaking gear pump assembly20. Upon completion of the repair or replacement of the failed or leaking gear pump assembly20, the repaired gear pump assembly20, or the new gear pump assembly20, can effectively be re-inserted into the bank or array of gear pump assemblies20whereupon, still further, the rotary drive shaft234can be re-installed in connection with the plurality of rotary gear pump assemblies20so as to again be operatively engaged with each one of the plurality of rotary gear pump assemblies20. Still yet further, if one of the gear pump assemblies20should experience failure and effectively become frozen, the failed and frozen gear pump assembly20will effectively prevent rotation of the rotary drive shaft234whereby the failed or frozen gear pump assembly20can experience or undergo further damage, and in turn, cause operative freezing or failure of the other gear pump assemblies20which are rotatably engaged with and driven by means of the common rotary drive shaft234.

Accordingly, a need existed in the art for a new and improved gear pump assembly for use in connection with liquid dispensing assemblies wherein the liquid dispensing assembly would comprise a plurality of rotary, gear-type pump assemblies which are mounted upon the liquid dispensing assembly such that all of the gear pump assemblies would be independent with respect to each other, wherein the plurality of rotary, gear-type pump assemblies would be operatively driven by means of a common rotary drive shaft in such a manner that no external dynamic seals would be required, wherein any particular one of the rotary, gear-type pump assemblies could be readily removed from the array or bank of rotary, gear-type pump assemblies independently of the other rotary, gear-type pump assemblies, and subsequently be re-inserted into the array or bank of rotary, gear-type pump assemblies, or replaced by means of a new rotary, gear-type pump assembly, and wherein still further, as a result of the plurality of rotary, gear-type pump assemblies being independent with respect to each other and not being operatively driven by means of, or mounted upon, a common internally disposed rotary drive shaft, then should a particular one of the rotary, gear-type pump assemblies experience a failure, the failed rotary, gear-type pump assembly would not experience additional damage or cause the other rotary, gear-type pump assemblies to experience freezing or failure. The aforenoted need in the art was addressed by means of the rotary, gear-type pump assemblies disclosed within U.S. Pat. No. 6,688,498 which issued to McGuffey on Feb. 10, 2004, which patent is hereby incorporated herein by reference.

More particularly, as disclosed withinFIG. 2, which corresponds substantially toFIG. 4of the aforenoted patent to McGuffey, it is seen that each one of the rotary, gear-type pump assemblies310comprises a housing defined by means of a sandwiched construction which includes an intermediate or central plate316. The central or intermediate plate316is provided with a plurality of cutout regions318,320,322, and a plurality of gear members324,326,328are respectively rotatably disposed within the cutout regions318,320,322such that the three gear members324,326,328are disposed in a substantially coplanar manner with respect to the central or intermediate plate316. Gear member324comprises a pump driven gear, gear member326comprises a pump drive gear which is operatively enmeshed with the pump driven gear324, and gear member328comprises a pump idler gear which is operatively enmeshed with the pump drive gear326. Each one of the gear members324,326,328is respectively fixedly mounted upon a pin, axle, or shaft member330, and opposite ends of the gear pins, axles, or shafts330are rotatably disposed within bearing members which, while not being shown withinFIG. 2, are fully disclosed and illustrated within the aforenoted patent to McGuffey. The bearing members, not shown, are, in turn, disposed within recesses which are defined within or upon interior side surface portions of the side plates of the housing sandwich structure.

In this manner, the gear members324,326,328are effectively rotatably mounted internally within the housing sandwich structure. This particular structural arrangement, by means of which the gear members324,326,328are mounted upon the side plates of the rotary, gear-type pump assembly310, is one of the critically important, and unique and novel, features characteristic of the rotary, gear-type pump assembly310, as constructed in accordance with the principles and teachings of the invention as set forth in the aforenoted patent to McGuffey, and which will likewise play a critically important inventive role in connection with the present invention as will be set forth hereinafter. More particularly, it is noted that all of the rotary shafts330and the bearing members, not shown, are disposed in an entirely enclosed or encased manner within the internal confines of the sandwiched plate construction comprising the housing of the rotary, gear-type pump assembly310. Viewed from a different point of view, none of the rotary shafts330and bearing members, not shown, project outwardly through, or extend externally of, the side plates of the gear pump housing, and in this manner, the need for external dynamic shaft seals, which have often conventionally proven to be sources of external leakage of the fluid being pumped and dispensed by means of the rotary, gear-type pump assembly310, has effectively been eliminated or obviated. It is noted further that in order to fixedly secure together the plate members comprising the sandwiched construction of the housing of the rotary, gear-type pump assembly310, as well as to ensure the proper coaxial alignment of the bearing member recesses defined within the side plates of the gear pump housing, with respect to the cutout regions318,320,322, defined within the central or intermediate plate316, so as to properly house, accommodate, and mount the three gear members324,326,328, and their associated shafts330and bearing members, not shown, upon the plate members of the rotary, gear-type pump assembly310, a plurality of screws and alignment pins extend through suitable bores, not numbered for clarity purposes, which are defined within the plate members of the rotary, gear-type pump assembly310as can be seen in connection with central or intermediate plate316.

With reference continuing to be made toFIG. 2, and as will be more fully appreciated hereinafter, each one of the pump driven gears324of each one of the rotary, gear-type pump assemblies310is adapted to be drivingly enmeshed with a manifold pump drive gear, not shown withinFIG. 2but fully disclosed and illustrated within the aforenoted patent to McGuffey, wherein the plurality of manifold pump drive gears are drivingly or rotatably mounted upon a common drive shaft which extends axially through a drive gear manifold, also not shown withinFIG. 2but fully disclosed and illustrated within the aforenoted patent to McGuffey. The drive shaft, for rotatably driving all of the manifold pump drive gears, is adapted to be driven by means of a suitable drive motor and gearbox assembly, also not shown withinFIG. 2but fully disclosed and illustrated within the aforenoted patent to McGuffey, and the hot melt adhesive material, to be metered and dispensed by means of each one of the rotary, gear-type pump assemblies310, is introduced into the drive gear manifold by means of a liquid inlet support port to which a suitable supply hose is connected so as to conduct hot melt adhesive material thereinto from an external or remote adhesive supply unit (ASU).

When the hot melt adhesive material is introduced into the drive gear manifold, the hot melt adhesive material will enter liquid supply cavities which are respectively defined around each one of the manifold pump drive gears, and each one of the liquid supply cavities is, in turn, respectively fluidically connected to a liquid accumulator cavity which is located at the enmeshed interface defined between each one of the manifold pump drive gears and the pump driven gears324of a particular one of the rotary, gear-type pump assemblies310. As is apparent fromFIG. 2, while a first arcuate portion of each pump driven gear324is drivingly enmeshed with its respective pump drive gear326, a second arcuate portion of each pump driven gear324projects radially outwardly through an end face402of the central or intermediate plate316of each one of the rotary, gear-type pump assemblies310so as to be drivingly enmeshed with a respective one of the manifold pump drive gears. Accordingly, as the drive motor and gearbox assembly, not shown withinFIG. 2but fully disclosed and illustrated within the aforenoted patent to McGuffey, causes rotation of the common drive shaft, and therefore rotation of each one of the manifold pump drive gears, in the counterclockwise direction, the pump driven gear324of each one of the rotary, gear-type pump assemblies310will be driven in the clockwise direction CW, each one of the pump drive gears326will be driven in the counterclockwise direction CCW, and each one of the pump idler gears328will be driven in the clockwise direction CW, as viewed inFIG. 2. As can additionally be seen fromFIG. 2, the diametrical extent of the cutout region318defined within the central or intermediate plate316of each one of the rotary, gear-type pump assemblies310is substantially larger than the diametrical extent of the pump driven gear324of each one of the rotary, gear-type pump assemblies310.

Therefore, when the liquid, that is, the hot melt adhesive, which is to be pumped through the rotary, gear-type pump assembly310and ultimately dispensed from the dispensing assembly, not shown inFIG. 2, is supplied to each one of the aforenoted liquid supply cavities and each one of the liquid accumulator cavities, oppositely oriented liquid flow paths404,406are effectively defined between the inner peripheral wall of cutout region318and the outer periphery of the pump driven gear324despite the fact that the driven gear324is being driven in the clockwise direction CW. Subsequently, the liquid portions, originally flowing along the flow paths404,406, are respectively entrained by means of each pump drive gear326and each pump idler gear328and conducted toward a common liquid inlet cavity408which is effectively formed adjacent to the interface defined between the cutout regions320,322that are formed within each central or intermediate plate316of each rotary, gear-type pump assembly310as may be appreciated fromFIG. 2. Ultimately, the hot melt adhesive is, in turn, conducted from the common liquid inlet cavity408to control valve assemblies and dispensing nozzles or applicator heads by means of suitable fluid passageways defined within each one of the rotary, gear-type pump assemblies310and the drive gear manifold.

While the aforenoted gear pump assemblies of McGuffey were disclosed within the aforenoted patent U.S. Pat. No. 6,688,498 as being utilized in an integral manner with a hot melt adhesive applicator head or dispensing assembly as a result of, for example, being mounted directly upon the applicator head or dispensing assembly, circumstances may arise when it is not possible or practical to utilize such rotary, gear-type pump assemblies in an integral manner with a hot melt adhesive applicator head or dispensing assembly. One possible instance may be, for example, wherein all of the applicator heads or dispensing nozzles are not disposed at one location. In this instance, the applicator heads or dispensing nozzles are to be fluidically connected to the aforenoted rotary, gear-type pump assemblies by means of suitable hose structures for conveying the hot melt adhesive material from the plurality of rotary, gear-type metering pumps to the applicator heads or dispensing nozzles, however, it is undesirable that such hose structures have substantially large or elongated lengths in that predeterminedly desired pressure levels, and precisely metered or predetermined volumes of the hot melt adhesive material, are difficult to attain and maintain within such hose structures when the hose structures comprise substantial or significant length dimensions. It is therefore desirable to, in effect, fluidically connect the precisely metered outputs of the plurality of rotary, gear-type metering pumps to the applicator heads or dispensing nozzles by means of relatively short hose structures.

In this manner, predeterminedly desired pressure levels, and precisely metered or predetermined volumes of the hot melt adhesive material, can be attained and maintained such that precisely metered or predetermined volumes of hot melt adhesive material can in fact be dispensed onto predetermined substrate locations. Still yet further, while the rotary, gear-type pump assemblies disclosed within the afore-noted patent to McGuffey must necessarily be supplied with the hot melt adhesive material, which is already disposed in its heated, liquid state, by means of a suitable supply hose from a remotely located adhesive supply unit (ASU), it is sometimes desirable to have a reservoir tank integrally disposed, mounted upon, or operatively associated with the drive gear manifold, and the plurality of rotary, gear-type pump assemblies which are also mounted upon the drive gear manifold, such that, for example, solid adhesive material may be stored or disposed within the reservoir tank. Accordingly, when the same is subsequently melted within the reservoir tank, the melted, hot melt adhesive material can be fluidically conducted into the drive gear manifold so as to, in turn, be fluidically conveyed to the plurality of rotary, gear-type metering pumps, or alternatively, a supply of the hot melt adhesive material may be stored within the reservoir tank in preparation for conveyance to the drive gear manifold and the plurality of rotary, gear-type metering pumps.

A need therefore exists in the art for a new and improved hot melt adhesive metering pump assembly, and an integral reservoir tank fluidically connected thereto, wherein the hot melt metering pump assembly would effectively have its own hot melt adhesive material supply source connected thereto as a result of the integral reservoir tank effectively comprising an adhesive supply unit (ASU), wherein the hot melt adhesive metering pump assembly would have a compact structure such that the multitude of rotary, gear-type metering pumps could be disposed within a minimal amount of space defined within the drive gear manifold, wherein each one of the rotary, gear-type metering pumps could be independently installed within and removed from the drive gear manifold, and wherein further, a base portion of the integral reservoir tank would be provided with a plurality of output hose connections such that the integral reservoir tank could be fluidically connected to a plurality of applicator heads or dispensing nozzles by means of relatively short hose structures whereby the plurality of rotary, gear-type metering pumps could output predeterminedly desired pressure levels, and precisely metered or predetermined volumes of the hot melt adhesive material, and the pressure levels and precisely metered or predetermined volumes of such dispensed hot melt adhesive materials could be attained and maintained such that the precisely metered or predetermined volumes of hot melt adhesive material can in fact be dispensed onto predetermined substrate locations.

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 hot melt adhesive metering pump assembly, and an integral reservoir tank fluidically connected thereto, for supplying predetermined or precisely metered volumes of hot melt adhesive material toward applicator head or dispensing nozzle structures. The integral reservoir tank effectively serves as a built-in adhesive supply unit (ASU) for the hot melt adhesive metering pump assembly, and the hot melt adhesive metering pump assembly comprises a plurality of rotary, gear-type metering pumps which are arranged in a compact, longitudinally spaced manner upon a drive gear manifold such that the rotational axes of the plurality of rotary, gear-type metering pumps are disposed parallel and adjacent to one side of the drive gear manifold. All of the driven gears of the plurality of rotary, gear-type metering pumps are respectively driven by manifold pump drive gears which are rotatably mounted upon a common motor-driven rotary drive shaft rotatably disposed within the drive gear manifold, and a first side wall member of a base portion of the reservoir tank is integrally connected to a side wall portion of the drive gear manifold, while a second side wall member of the base portion of the reservoir tank is provided with a plurality of hose connections to which hot melt adhesive delivery hoses are to be connected so as to respectively conduct or convey the precisely metered amounts of the hot melt adhesive material, outputted by means of the plurality of rotary, gear-type metering pumps mounted upon the drive gear manifold, toward the applicator heads or dispensing nozzles. In this manner, the plurality of rotary, gear-type metering pumps could out-put predeterminedly desired pressure levels, and precisely metered or predetermined volumes of the hot melt adhesive material, and the pressure levels and precisely metered or predetermined volumes of such dispensed hot melt adhesive materials could be attained and maintained such that the precisely metered or predetermined volumes of hot melt adhesive material can in fact be dispensed onto predetermined substrate locations.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, and more particularly toFIGS. 3-5thereof, a new and improved hot melt adhesive metering pump assembly and integral reservoir tank structure, constructed in accordance with the teachings and principles of the present invention, is illustrated so as to show the cooperative parts thereof, and is generally indicated by the reference character510. More particularly, it is seen that the new and improved hot melt adhesive metering pump assembly and integral reservoir tank structure, constructed in accordance with the principles and teachings of the present invention, is seen to comprise an axially elongated drive gear manifold512wherein a plurality of manifold pump drive gears, only one of which is shown at514withinFIG. 5, are disposed internally within the axially elongated drive gear manifold512. The plurality of manifold pump drive gears514are mounted in an axially spaced manner upon a common drive shaft516which extends axially through the drive gear manifold512, and a plurality of rotary, gear-type metering pump assemblies518are mounted in an axially spaced manner upon an upper side surface portion520of the axially elongated drive gear manifold512. As can best be seen fromFIG. 4, each one of the rotary, gear-type metering pump assemblies518is substantially identical to the rotary, gear-type metering pump assembly310as disclosed withinFIG. 2except for the fact that the rotary, gear-type metering pump assembly310ofFIG. 2has effectively been rotated 90° in the clockwise direction so as to effectively define the rotary, gear-type metering pump assembly518. Accordingly, it is to be appreciated that, as was the case with the rotary, gear-type metering pump assembly310, each one of the rotary, gear-type metering pump assemblies518comprises a sandwiched housing structure which includes a central or intermediate plate522upon or within which a plurality of gears524,526,528are rotatably mounted in a substantially coplanar manner upon axially oriented shafts530.

More particularly, gear member524comprises a pump driven gear, gear member526comprises a pump drive gear that is operatively enmeshed with the pump driven gear524, and gear member528comprises a pump idler gear which is operatively enmeshed with the pump drive gear526. In view of the fact that each one of the rotary, gear-type metering pump assemblies518as disclosed withinFIG. 4is substantially identical to the rotary, gear-type metering pump assembly310as disclosed withinFIG. 2, a detailed description of the rotary, gear-type metering pump assembly518will be omitted herefrom for brevity purposes except for any description that is of course pertinent for the purposes of disclosure and understanding of the new and improved hot melt adhesive metering pump assembly and integral reservoir tank structure510which has been constructed in accordance with the principles and teachings of the present invention. Accordingly, it can be further appreciated that, as was the case with the rotary, gear-type metering pump assembly310as disclosed withinFIG. 2, the plurality of rotary, gear-type metering pump assemblies518, as mounted atop the axially elongated drive gear manifold512, are axially spaced predetermined distances from each other such that the pump driven gears524of the plurality of rotary, gear-type metering pump assemblies518can be respectively disposed in enmeshed engagement with the axially spaced manifold pump drive gears514disposed within the axially elongated drive gear manifold512. It is further seen that the axes532,534,536of the pump driven gear524, the pump drive gear526, and the pump idler gear528are disposed parallel and adjacent to the upper side surface portion520of the axially elongated drive gear manifold512.

Still further, as can be appreciated fromFIGS. 3 and 5, the axially oriented common drive shaft516is adapted to be driven by means of a suitable drive motor and gearbox assembly, and through means of a suitable coupling mechanism, not shown but fully disclosed and illustrated within the aforenoted patent to McGuffey, and a plurality of gear pump, torque-overload release clutch mechanisms, which are also not shown but are likewise fully disclosed within the aforenoted patent to McGuffey, are mounted upon the common, axially oriented drive shaft516at predetermined axially spaced positions thereof so as to respectively drivingly engage the plurality of pump drive gears514. More particularly, as is disclosed within the aforenoted patent to McGuffey, the axially oriented drive shaft516is provided with a plurality of key members which are fixedly mounted thereon at predetermined axially spaced positions for respectively operatively engaging a plurality of keyways which are defined within each one of the gear pump, torque-overload release clutch mechanisms so as to effectively define a drive connection therebetween. The provision of the rotary drive shaft516, the key members, the gear pump, torque-overload release clutch mechanisms, and the manifold pump drive gears514within the axially elongated drive gear manifold512enables any one of the plurality of rotary, gear-type pump assemblies518to be independently engaged with, and disengaged from, its respective one of the plurality of manifold pump drive gears514without adversely affecting the operation of the other ones of the rotary, gear-type pump assemblies518.

Continuing further, and with reference continuing to be made toFIGS. 3-5, a reservoir tank538, which may store a supply of hot melt adhesive material therein so as to effectively serve as an adhesive supply unit (ASU) for the plurality of rotary, gear-type metering pump assemblies518, or alternatively, may additionally comprise melting apparatus for also melting solid adhesive material, has a base portion540which is integrally connected to one side of the axially elongated drive gear manifold512. The base portion540of the reservoir tank538is provided with a plurality of outlet ports542within which a plurality of outlet port hose connections, not shown, are adapted to be installed such that a plurality of suitable conveyance hoses, schematically illustrated at544, are adapted to be connected in order to transmit, transport, or convey the precisely metered liquid or hot melt adhesive material to suitable applicator head or dispensing mechanisms. It is further sent that the liquid or hot melt adhesive material, to be dispensed through the plurality of outlet port hose connections544, is initially introduced into, or supplied to, the axially elongated drive gear manifold512, from the reservoir tank538, through means of a liquid inlet supply port546, which is formed within the base portion540of the reservoir tank538, and a fluid passageway548which fluidically interconnects the inlet support port546to each one of a plurality of liquid supply cavities552which are defined within the axially elongated drive gear manifold512and which annularly surround each one of the manifold pump drive gears514, as can best be seen inFIG. 5. Each one of the liquid supply cavities552is, in turn, respectively fluidically connected to a liquid accumulator cavity, not illustrated for clarity purposes, which is located adjacent to the enmeshed interface defined between each one of the manifold pump drive gears514and a respective one of the pump driven gears524.

As has been previously described in connection with the rotary, gear-type pump assembly310disclosed withinFIG. 2, and as can best be seen fromFIG. 4, while a first arcuate portion of each one of the pump driven gears524is drivingly enmeshed with a respective one of the pump drive gears526, a second arcuate portion of each pump driven gear524projects radially outwardly through an end face553of the central or intermediate plate522of each one of the rotary, gear-type pump assemblies518so as to be drivingly enmeshed with a respective one of the manifold pump drive gears514. Accordingly, as the drive motor and gearbox assembly, not shown, causes rotation of the axially oriented common drive shaft516, and therefore each manifold pump drive gear514in, for example, the counterclockwise direction, the pump driven gear524of each one of the gear pump assemblies518is driven in the clockwise direction, the pump drive gear526is driven in the counterclockwise direction, and the pump idler gear528is driven in the clockwise direction. As can additionally be best seen fromFIG. 4, the diametrical extent of the cutout region554defined within the central or intermediate plate522of each one of the gear pump assemblies518is substantially larger than the diametrical extent of the pump driven gear524of each one of the gear pump assemblies518. Accordingly, when the liquid, which is to be pumped through each one of the gear pump assemblies518, and ultimately dispensed from a respective one of the outlet port hose connections544, is supplied to each one of the liquid supply cavities552and each liquid accumulator cavity, not designated by a reference character for clarity purposes, oppositely oriented liquid flow paths556,558are effectively defined between the inner peripheral wall of the cutout region554and the outer periphery of the pump driven gear524despite the fact that the pump driven gear524is being driven in the clockwise direction. Subsequently, the liquid portions, originally flowing along the flow paths556,558, are respectively entrained by means of the pump drive gear526and the pump idler gear528and are conducted toward a common liquid inlet cavity560which is effectively formed at the interface defined between the cutout regions562,564formed within the central or intermediate plate522as may best be appreciated fromFIG. 4.

With reference therefore now being additionally made again toFIG. 5, in conjunction with each one of the aforenoted common liquid inlet cavities560which are effectively formed at the interfaces defined between the cutout regions562,564formed within each one of the central or intermediate plates522of each one of the gear pump assemblies518, a liquid outlet cavity, not illustrated but disclosed within the aforenoted patent to McGuffey, is formed within one of the side plates566of each one of the gear pump assemblies518so as to be in fluidic communication with its respective one of the common liquid inlet cavities560. A pump outlet port568is defined within a lower portion of the side plate566of each one of the gear pump assemblies518, as best seen inFIG. 5, and a fluid passageway570, internally defined within the side plate566, fluidically connects the liquid outlet cavity, not shown, to the pump outlet port568. As can be further appreciated fromFIG. 5, once a metered flow of the hot melt adhesive material is outputted through means of the pump outlet port568of each one of the gear pump assemblies518, the hot melt adhesive material is conducted through a first, relatively small, substantially vertically oriented fluid passageway572, which extends vertically within the axially elongated drive gear manifold512, and a second fluid passageway574which extends horizontally within the axially elongated drive gear manifold512so as to be fluidically connected to a respective one of the outlet ports542.

Thus, it may be seen that in accordance with the present invention, there has been provided a new and improved hot melt adhesive metering pump assembly and integral reservoir tank structure for supplying predetermined or precisely metered volumes of hot melt adhesive material toward applicator head or dispensing nozzle structures. The new and improved hot melt adhesive metering pump assembly and integral reservoir tank structure comprises an axially elongated drive gear manifold upon which a hot melt adhesive metering pump assembly, comprising a plurality of rotary, gear-type metering pumps, are fixedly disposed within a linear array, and a reservoir tank is integrally connected to a side wall portion of the drive gear manifold. The integral reservoir tank effectively serves as a built-in adhesive supply unit (ASU) for the hot melt adhesive metering pump assembly, and the plurality of rotary, gear-type metering pumps are arranged in a compact, longitudinally spaced manner upon the drive gear manifold such that the rotational axes of the plurality of rotary, gear-type metering pumps are disposed parallel and adjacent to one side of the drive gear manifold.

All of the driven gears of the plurality of rotary, gear-type metering pumps are respectively driven by manifold pump drive gears which are rotatably mounted upon a common motor-driven rotary drive shaft rotatably disposed within the drive gear manifold, and a first side wall member of a base portion of the reservoir tank is integrally connected to a side wall portion of the drive gear manifold, while a second side wall member of the base portion of the reservoir tank is provided with a plurality of hose connections to which hot melt adhesive delivery hoses are to be connected so as to respectively conduct or convey the precisely metered amounts of the hot melt adhesive material, outputted by means of the plurality of rotary, gear-type metering pumps mounted upon the drive gear manifold, toward the applicator heads or dispensing nozzles. In this manner, the plurality of rotary, gear-type metering pumps can output predeterminedly desired pressure levels, and precisely metered or predetermined volumes of the hot melt adhesive material, and the pressure levels and precisely metered or predetermined volumes of such dispensed hot melt adhesive materials can be attained and maintained such that the precisely metered or predetermined volumes of hot melt adhesive material can in fact be dispensed onto predetermined substrate locations.