1. Technical Field
A recirculation system is disclosed for multiple fluid dispensing and formulation machines wherein the fluids being dispensed have limited amounts of volatile organic compounds (VOCs) and therefore have the propensity to become non-homogeneous and clog the dispense valves. The recirculation system prevents the settling out of heavier materials such as pigments of a colorant or tint, improves the dispense accuracy and reduces the maintenance of the multiple fluid dispensing machines.
2. Description of the Related Art
Systems for dispensing a plurality of different fluids into a container are known. For example, systems for dispensing paint base materials and colorants into a paint container are known. These paint systems may use twenty or more different colorants to formulate a paint mixture. Each colorant is contained in a separate canister or package and may include its own dispensing pump. The colorants and the respective pumps may be disposed on a turntable or along one or more stationary horizontal rows. In a turntable system, the turntable is rotated so that the colorant to be dispensed is moved to a position above the container being filled. In designs using one or more horizontal rows, the container may be moved laterally to the appropriate colorant/pump or the colorants may be dispensed through a manifold.
In paint dispensing applications, precision is essential as the color formulations or paint formulations require the addition of precise amounts of tints or colorants so the chosen color of paint does not vary from container to container. One way in which the precision of a paint dispensing systems is compromised is a non-uniform condition of a colorant or tint caused by a settling out of heavier components of the colorant slurry during storage in the canister and prior to dispensing or between dispenses. Specifically, the actual pigments of colorant slurries tend to be heavier than the remaining components, such as the solvent. As these heavier materials gather or collect towards the bottom of the canister under the force of gravity, the colorant slurry has a non-uniform concentration from the bottom of the canister to the top of the canister. As a result, the heavier pigment materials may be dispensed in a higher concentration when the canister is relatively full and at a lower concentration when the canister is close to being empty. The non-uniformity of the colorant slurry leads to inaccuracies in the final paint formulation.
As a result, there is a need for an improved paint colorant or tint canister for use in automated paint dispensing machines that avoids this problem. Further, the above problems are exacerbated by European and California regulations that are becoming increasingly hostile to the use of volatile organic components (VOCs) in paints and paint colorants. VOCs are very effective solvents at maintaining colorants, pigments and other heavier materials in a uniform slurry. The elimination or restriction of VOCs reduces the time it takes for heavier materials to settle out of a slurry that needs to be uniform for accuracy purposes. For example, low-VOC or no-VOC paint pigments require frequent recirculation to ensure that the final formulation is accurately dispensed.
In satisfaction of the aforenoted needs, a dispenser for dispensing multiple fluids is disclosed. The dispenser comprises a table coupled to a table motor for rotating the table between at least two positions including a dispense position and a recirculation position. A plurality of canisters, a plurality of pumps, a plurality of pump motors, a plurality of valve assemblies, a plurality of dispense ports and a controller also form part of the disclosed dispenser. Each canister is in communication with its assigned pump. Each pump is in communication with an inlet of its assigned valve assembly. Each pump is also linked to its assigned pump motor. The table is coupled to the plurality of valve assemblies. In the dispense position, the table moves each valve assembly to provide communication between its assigned canister and its assigned dispense port. In the recirculation position, the table moves each valve assembly to provide communication between its respective pump and its respective canister. The controller is linked to the table motor and each pump motor for selectively dispensing fluids when the table and valve assemblies are in the dispense position and for circulating fluids back to their respective canisters when the table and valve assemblies are in the recirculation position.
In a refinement, the controller selectively controls activation of the pump motors so that, in the dispense position, a single fluid may be dispensed if the controller activates only a single pump motor. In contrast, multiple fluids may be dispensed if the controller activates multiple pump motors at a given time.
In a refinement, recirculation may be carried out on a periodic or continuous basis.
In a refinement, each valve assembly comprises a valve housing comprising an inlet in communication with its respective pump and a recirculation outlet in communication with its respective canister. Each valve housing accommodates a valve body that comprises a first end connected to a handle and a second end comprising a dispense passageway that provides communication between the inlet of its associated valve assembly and its associated dispense port when the table and valve assemblies are in the dispense position. The valve body further comprises a recirculation slot that provides communication between the inlet and the recirculation outlet of its respective valve housing when the table and valve assemblies are in the recirculation position.
In another refinement, each handle is connected to a shaft. Each shaft is received in a slot disposed in the table. Rotation of the table between the dispense and recirculation positions cause each shaft and handle to move the valve body between dispense and recirculation positions.
In another refinement, the dispenser also comprises a first sensor linked to the controller for sensing when the table is in the dispense position. In such a refinement, the first sensor may be linked to the controller.
In another refinement, the dispenser may comprise a second sensor for sensing when the table is in the recirculation position. In such a refinement, the second sensor may be linked to the controller.
In another refinement, the table may comprise a plurality of radial slots. Each slot may accommodate a shaft connected to a valve assembly so that rotation of the table between the dispense and recirculation positions causes each shaft to move its respective valve assembly between the dispense and recirculation positions.
One disclosed dispenser for dispensing multiple fluids comprises a table coupled to a table motor for rotating the table between at least two positions including a dispense position and a recirculation position. The dispenser also comprises a plurality of canisters, a plurality of pumps, a plurality of pump motors, a plurality of valve assemblies, a plurality of dispense ports and a controller linked to at least the table motor and each pump motor. Each canister is in communication with its assigned pump. Each pump is in communication with an inlet of its assigned valve assembly. Each pump is also linked to its assigned pump motor. The table is coupled to the plurality of valve assemblies. Each valve assembly comprises a valve housing comprising an inlet in communication with its respective pump and a recirculation outlet in communication with its respective canister. Each valve housing accommodates a valve body comprising a first end connected to a handle and a second end comprising a dispense passageway that provides communication between the inlet of its associated valve assembly and its associated dispense port when the table and valve assemblies are in the dispense position. The valve body further comprises a recirculation slot that provides communication between the inlet and the recirculation outlet of its respective valve housing when the table and valve assemblies are in the recirculation position.
In a refinement, the table is coupled to each valve assembly and, in the dispense position, the table has moved each valve assembly to provide communication between its assigned canister and its assigned dispense port. In the recirculation position, the table has moved each valve assembly to provide communication between its respective pump and its respective canister.
In a refinement, the controller selectively controls activation of the pump motors. For example, in the dispense position, the controller may activate only a single pump so that only a single fluid is dispensed at a given time. In contrast, the controller may activate multiple pump motors so that multiple fluids are dispensed simultaneously.
In a refinement, each handle of each valve assembly is connected to a shaft. Each shaft is received in a radial slot disposed in the table. Rotation of the table between the dispense and recirculation positions causes each shaft and handle to move each valve body between the dispense and recirculation positions.
Sensors may be employed for communicating to the controller when the table is in the dispense position or when the table is in the recirculation position.
A valve assembly is also disclosed which comprises a dispense port and a valve housing comprising an inlet in communication with a pump and a recirculation outlet in communication with a canister. The valve housing also accommodates a valve body comprising a first end connected to a handle and a second end comprising a dispense passageway that provides communication between the inlet of the valve assembly and the dispense port when the valve body is in a dispense position. The valve body further comprises a recirculation slot that provides communication between the inlet and recirculation outlet of the valve housing when the valve body is in the recirculation position.
In a refinement, the recirculation slot extends axially along the valve body to provide communication between the inlet and recirculation outlet of the valve housing when the valve body is in the recirculation position.
In a refinement, the dispense passageway extends trans-axially through the valve body.
Other advantages and features will be apparent from the following detailed description when read in conjunction with the attached drawings.
For a more complete understanding of the disclosed methods and apparatuses, reference should be made to the embodiment illustrated in greater detail on the accompanying drawings, wherein:
It should be understood that the drawings are not necessarily to scale and that the disclosed embodiments are sometimes illustrated diagrammatically and in partial views. In certain instances, details which are not necessary for an understanding of the disclosed methods and apparatuses or which render other details difficult to perceive may have been omitted. It should be understood, of course, that this disclosure is not limited to the particular embodiments illustrated herein.
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One particularly problematic family of colorants is yellow iron oxide colorants. Recirculation of the colorant slurries is one way of minimizing the separation of the materials within the colorant slurry and maintaining homogenization. Further, the recirculation can have the beneficial effect on a thick fluid, such as shear thinning The disclosed dispenser 10 is particularly useful for these types of material and similar materials.
While only certain embodiments have been set forth, alternatives and modifications will be apparent from the above description to those skilled in the art. These and other alternatives are considered equivalents and within the spirit and scope of this disclosure and the appended claims.
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Number | Date | Country | |
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20110290823 A1 | Dec 2011 | US |