Adhesive dispensing device having optimized reservoir and capacitive level sensor

Patent metadata

Field	Value
Publication number	US-10099243-B2
Application number	US-201614991952-A
Country	US
Kind code	B2
Filing date	Jan 10, 2016
Priority date	Sep 20, 2012
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

An adhesive dispensing device includes a heater unit for melting adhesive, a fill system communicating with a receiving space for feeding the heater unit, and a reservoir for receiving melted adhesive from the heater unit. The dispensing device also includes a capacitive level sensor located along a sidewall of the receiving space such that the level of adhesive in the receiving space can be detected by sensing the difference in dielectric capacitance where the adhesive is located compared to where air acts as the dielectric. The size of the driven electrode produces a broader sensing window capable of generating multiple control signals corresponding to different fill levels of adhesive. The receiving space and reservoir are minimized in size so that adhesive is not held at elevated temperatures long enough to char or degrade.

First claim

What is claimed is:

1. An adhesive dispensing device, comprising:
a melt subassembly including a heater unit adapted to melt and heat an adhesive, a receiving space positioned to receive unmelted adhesive and deliver the adhesive into said heater unit, a reservoir for receiving the adhesive from said heater unit, and a pump for directing the adhesive from said reservoir to an outlet, said receiving space and reservoir defining a collective storage volume and said heater unit defining a surface area in contact with the adhesive; and
a control subassembly including a controller configured to operate said pump and said heater unit to dispense adhesive through said outlet,
a relation of the collective storage volume of said receiving space and said reservoir to the surface area of said heater unit being less than 1 cubic inch of volume to 1 square inch of surface area.

2. The adhesive dispensing device of claim 1 , wherein the relation of the collective storage volume to the surface area of said heater unit is about 0.7 cubic inches of volume to 1 square inch of surface area.

3. The adhesive dispensing device of claim 1 , wherein said control subassembly is adapted to actuate supply of unmelted adhesive to said receiving space as melted adhesive is pumped from said reservoir, and wherein the unmelted adhesive delivered to said receiving space defines a round pellet shape that is configured to be melted at the heater unit.

4. The adhesive dispensing device of claim 3 , wherein said receiving space is at least partially defined by a sidewall, and a level sensor having an electrically driven electrode is mounted along said sidewall such that a fill level of adhesive in said receiving space is detected by a change in dielectric capacitance from said electrically driven electrode to a ground at least partially defined at said sidewall.

5. The adhesive dispensing device of claim 3 , wherein said melt subassembly further comprises:
a cyclonic separator unit configured to receive pellets of adhesive in an air flow and reduce the velocity of the air flow and the pellets of adhesive before depositing the pellets of adhesive into said receiving space.

6. The adhesive dispensing device of claim 1 ,
wherein the reservoir defines an open top end and a bottom end opposite the open top end, wherein the reservoir is operatively coupled to said heater unit, the pump is located at least partially within a heated housing, and said heated housing heats said pump and adhesive within said pump during startup and regular operation of the adhesive dispensing device,
the melt subassembly further including a manifold in fluid communication with said reservoir and said pump, said manifold including at least one conduit that extends from the bottom end of the reservoir to the pump, wherein the conduit is configured to deliver adhesive from the reservoir to the pump, and said pump is in fluid communication with said reservoir to receive the heated and melted adhesive from said reservoir through the conduit.

7. The adhesive dispensing device of claim 6 , wherein said manifold includes at least one outlet configured to receive adhesive that is removed from said reservoir by said pump.

8. The adhesive dispensing device of claim 7 , wherein said manifold defines said heated housing such that said manifold at least partially surrounds said pump and supplies heat energy to said pump.

9. The adhesive dispensing device of claim 8 , wherein said reservoir directly abuts said manifold so that said reservoir provides heat energy by conduction into said manifold for heating said pump.

10. The adhesive dispensing device of claim 9 , wherein said manifold is integrally formed as a unitary piece with said reservoir, thereby enabling the conduction of heat energy from said reservoir to said manifold and said pump.

11. The adhesive dispensing device of claim 8 , wherein the melt subassembly further comprises an insulating external housing at least partially surrounding said heater unit, said reservoir, and said manifold collectively in order to encourage conduction of heat energy to said pump.

12. The adhesive dispensing device of claim 1 ,
wherein the receiving space is defined by at least one sidewall and a top wall having an inlet aperture and the reservoir defines an open top end and a bottom end opposite the open top end,
the melt subassembly further compromising:
a fluid level sensor for measuring a fill level of the adhesive within said receiving space to determine when said receiving space needs to be refilled with adhesive; and
a manifold defining a conduit that extends from the bottom end of the reservoir to the pump, wherein the conduit is configured to deliver adhesive from the reservoir to the pump, said receiving space, said heater unit, said reservoir, and said manifold are positioned above and/or below one another in a common vertical plane, and said pump is vertically-oriented and is centered along another vertical plane spaced from and parallel to the common vertical plane.

13. The adhesive dispensing device of claim 12 , further comprising a cyclonic separator unit coupled to said receiving space, said cyclonic separator unit including an elongate pipe including a top end and a bottom end, said top end communicating with a tangential inlet pipe such that a flow of air and adhesive pellets flows from said tangential inlet pipe to spiral downwardly in said elongate pipe toward said bottom end and said inlet aperture of said receiving space, thereby decelerating the adhesive pellets before delivery into said receiving space.

14. The adhesive dispensing device of claim 1 , wherein said pump is located at least partially within a heated housing, wherein said heated housing heats said pump and adhesive within said pump during startup and regular operation of the melt subassembly.

15. The adhesive dispensing device of claim 12 , wherein said pump is located at least partially within a heated housing, wherein said heated housing heats said pump and adhesive within said pump during startup and regular operation of the heater unit.

16. The adhesive dispensing device of claim 1 ,
wherein the collective storage volume of said receiving space and said reservoir is less than 2 liters.

Assignees

• Nordson Corp

Inventors

• Clark Justin A
• Clark Steven
• Estelle Peter W
• Owen Jeffrey E
• Woodlief Robert J
• Jeter David R

Classifications

• A61B1/044

  for absorption imaging · CPC title

• B05C11/1042 Primary

  provided with means for heating or cooling the liquid or other fluent material in the supplying means upstream of the applying apparatus · CPC title

• G01F23/26

  by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields · CPC title

• G01F23/268

  mounting arrangements of probes · CPC title

• G01F23/263

  by measuring variations in capacitance of capacitors · CPC title