Fluid dispense pump with drip prevention mechanism and method for controlling same
First Claim
1. A material dispensing pump comprising:
- a feed screw including a cylindrical neck portion and a helical feed path defined between a major diameter and a minor diameter of the feed screw;
the feed screw being driven in a first direction of rotation during a dispensing operation of material to be dispensed;
a feed screw housing having a cavity, the feed screw extending through the cavity, the feed screw housing having an inlet port and an outlet port in communication with the cavity, the helical feed path being substantially sealed from ambient air between the inlet port and the outlet port by an O-ring positioned about the neck between the neck and the feed screw housing and a threaded spanner nut that applies pressure in a direction along a longitudinal axis of the feed screw that compresses the O-ring about the neck to substantially seal the helical path from ambient air;
a pressure unit for applying positive pressure to cause material to be presented to the inlet port at a desired rate during a dispensing operation such that the material flows through the helical feed path toward the outlet port; and
a material suspension unit for placing the material in the substantially sealed helical feed path in suspension by applying negative pressure to the material following the dispensing operation.
1 Assignment
0 Petitions
Accused Products
Abstract
A material dispensing pump includes a drip prevention system and method so as to avoid undesired dripping of the dispensed fluid. In one example, the fluid path is sealed. Positive pressure is applied to the fluid during a dispensing operation to present the fluid to the auger-style pump at a desired rate. Between dispensing operations, or when dispensing is completed, the fluid is placed in suspension, for example by applying a negative pressure, thereby preventing the fluid from being inadvertently released at the dispense tip. In addition, following a dispensing operation, the pump dispensing controller can be programmed to reverse the rotation of the feed screw, in order to draw the material in a reverse direction and to further suspend the fluid.
216 Citations
100 Claims
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1. A material dispensing pump comprising:
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a feed screw including a cylindrical neck portion and a helical feed path defined between a major diameter and a minor diameter of the feed screw;
the feed screw being driven in a first direction of rotation during a dispensing operation of material to be dispensed;a feed screw housing having a cavity, the feed screw extending through the cavity, the feed screw housing having an inlet port and an outlet port in communication with the cavity, the helical feed path being substantially sealed from ambient air between the inlet port and the outlet port by an O-ring positioned about the neck between the neck and the feed screw housing and a threaded spanner nut that applies pressure in a direction along a longitudinal axis of the feed screw that compresses the O-ring about the neck to substantially seal the helical path from ambient air; a pressure unit for applying positive pressure to cause material to be presented to the inlet port at a desired rate during a dispensing operation such that the material flows through the helical feed path toward the outlet port; and a material suspension unit for placing the material in the substantially sealed helical feed path in suspension by applying negative pressure to the material following the dispensing operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for dispensing material comprising:
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during a dispensing operation of material to be dispensed; driving a feed screw including a cylindrical neck portion and a helical feed path in a first direction of rotation, the feed screw being disposed in a cavity of a feed screw housing such that the helical feed path is substantially sealed from ambient air by positioning an O-ring about the neck between the neck and the feed screw housing and by applying pressure in a direction along a longitudinal axis of the feed screw that compresses the O-ring about the neck to substantially seal the helical path from ambient air; and applying positive pressure to the material to cause material to be presented to the helical feed path at a desired rate; and following the dispensing operation, placing the material in the substantially sealed helical feed path in suspension by applying negative pressure to the material. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A material dispensing pump comprising:
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a feed screw including a cylindrical neck portion and a helical feed path defined between a major diameter and a minor diameter of the feed screw;
the feed screw being driven in a first direction of rotation during a dispensing operation of material to be dispensed;a feed screw housing having a cavity, the feed screw extending through the cavity, the feed screw housing having an inlet port and an outlet port in communication with the cavity, the helical feed path being substantially sealed from ambient air between the inlet port and the outlet port by an O-ring positioned about the neck between the neck and the feed screw housing, the O-ring being under pressure in a direction along a longitudinal axis of the feed screw that compresses the O-ring about the neck to substantially seal the helical path from ambient air; a pressure unit for applying positive pressure to cause material to be presented to the inlet port at a desired rate during a dispensing operation such that the material flows through the helical feed path toward the outlet port; a material reservoir in communication with the inlet port, the material reservoir containing the material to be dispensed during the dispensing operation, wherein the material reservoir comprises a syringe, and wherein the positive pressure is applied to the material in the syringe; and a material suspension unit for placing the material in the substantially sealed helical feed path in suspension by applying negative pressure to the material following the dispensing operation, wherein the negative pressure comprises a vacuum provided by the pressure unit and drawn on the material in the syringe. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A method for dispensing material comprising:
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during a dispensing operation of material to be dispensed; driving a feed screw including a cylindrical neck portion and a helical feed path in a first direction of rotation, the feed screw being disposed in a cavity of a feed screw housing such that the helical feed path is substantially sealed from ambient air by positioning an O-ring about the neck between the neck and the feed screw housing and by applying pressure to the O-ring in a direction along a longitudinal axis of the feed screw that compresses the O-ring about the neck to substantially seal the helical path from ambient air; applying positive pressure to the material to cause material to be presented to the substantially sealed helical feed path at a desired rate; and providing the material from a material reservoir in communication with the helical feed path, wherein the material reservoir comprises a syringe, and wherein the positive pressure is applied to the material in the syringe; and following the dispensing operation, placing the material in the substantially sealed helical feed path in suspension by applying negative pressure to the material, wherein the negative pressure comprises a vacuum drawn on the material in the syringe. - View Dependent Claims (37, 38, 39, 40, 41, 42, 43)
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44. A material dispensing pump comprising:
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a feed screw including a cylindrical neck and a helical feed path defined between a major diameter and a minor diameter of the feed screw;
the feed screw being driven in a first direction of rotation during a dispensing operation of material to be dispensed;a feed screw housing having a cavity, the feed screw extending through the cavity, the feed screw housing having an inlet port and an outlet port in communication with the cavity, the helical feed path being substantially sealed from ambient air between the inlet port and the outlet port; a pressure unit for applying positive pressure to cause material to be presented to the inlet port at a desired rate during a dispensing operation such that the material flows through the helical feed path toward the outlet port; a material suspension unit for placing the material in suspension following the dispensing operation; an O-ring about the neck of the feed screw between the neck and the feed screw housing; and a threaded nut that applies pressure in a direction along a longitudinal axis of the feed screw that compresses the O-ring about the neck of the feed screw in order to substantially seal the helical feed path from ambient air between the inlet port and the outlet port. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60)
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61. A material dispensing pump comprising:
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a feed screw including a cylindrical neck portion and a helical feed path defined between a major diameter and a minor diameter of the feed screw; a feed screw housing having a cavity, the feed screw extending through the cavity, the feed screw housing having an inlet port and an outlet port in communication with the cavity, the helical feed path being substantially sealed from ambient air between the inlet port and the outlet port by an O-ring positioned about the neck between the neck and the feed screw housing, the O-ring being under pressure in a direction along a longitudinal axis of the feed screw that compresses the O-ring about the neck to substantially seal the helical path from ambient air; a pressure unit for applying positive pressure to cause material to be presented to the inlet port at a desired rate during a dispensing operation of material to be dispensed such that the material flows through the helical feed path toward the outlet port; a material suspension unit for placing the material in the substantially sealed helical feed path in suspension by applying negative pressure to the material following the dispensing operation; and a closed-loop servo motor coupled to the feed screw for driving the feed screw in a first direction of rotation during the dispensing operation and for driving the feed screw in a second direction of rotation opposite the first direction following the dispensing operation. - View Dependent Claims (62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72)
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73. A method for dispensing material comprising:
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during a dispensing operation of material to be dispensed; driving a feed screw including a cylindrical neck and a helical feed path in a first direction of rotation, the feed screw being disposed in a cavity of a feed screw housing such that the helical feed path is substantially sealed from ambient air by positioning an O-ring about the neck of the feed screw between the neck and the feed screw housing, and compressing the O-ring by applying pressure along a longitudinal axis of the feed screw to the O-ring using a threaded nut; and applying positive pressure to the material to cause material to be presented to the helical feed path at a desired rate; and following the dispensing operation, placing the material in suspension. - View Dependent Claims (74, 75, 76, 77, 78, 79, 80, 81, 82, 83)
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84. A method for dispensing material comprising:
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during a dispensing operation of material to be dispensed; driving a feed screw including a helical feed path in a first direction of rotation, the feed screw being disposed in a cavity of a feed screw housing such that the helical feed path is substantially sealed from ambient air by positioning an O-ring about the neck between the neck and the feed screw housing and applying pressure in a direction along a longitudinal axis of the feed screw that compresses the O-ring to substantially seal the helical path from ambient air; and applying positive pressure to the material to cause material to be presented to the helical feed path at a desired rate; and following the dispensing operation, placing the material in the substantially sealed helical feed path in suspension by applying negative pressure to the material and by driving the feed screw in a second direction of rotation opposite the first direction. - View Dependent Claims (85, 86, 87, 88, 89, 90, 91, 92)
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93. A cartridge for a material dispensing pump comprising:
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a feed screw including a cylindrical neck and a helical feed path defined between a major diameter and a minor diameter of the feed screw; a cartridge housing having a cavity, the feed screw extending through the cavity, the cartridge housing having an inlet port and an outlet port in communication with the cavity; an O-ring positioned about the neck between the neck of the feed screw and the cartridge housing that substantially seals the helical feed path from ambient air between the inlet port and the outlet port of the cartridge housing; a threaded nut that applies pressure in a direction along a longitudinal axis of the feed screw that compresses the O-ring about the neck of the feed screw. - View Dependent Claims (94, 95, 96, 97, 98, 99, 100)
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Specification