CROSS-REFERENCE TO RELATED APPLICATIONS:

The present application claims priority to U.S. Provisional Patent Application No. 61/243,231 , filed on September 17, 2009, the disclosure of which is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION:

Conventionally, systems for the controlled injection of fluid to ink flows include an injection pump, also known as a metering pump or a solvent pump. Commercial units, for example, use either air-operated or electrically operated pumps. The pump is controlled by a pump controller, which is, in turn, driven by the output of a sensor in the ink line or sump, where such sensor measures viscosity, pH or other ink property. In addition to the pump, overhead stirrers are typically used in the ink sump to blend any injected make-up fluid with the ink.

This complex apparatus has a large physical size, and a significant cost associated with it. Moreover, because each station on a printing press requires a make-up system, such a make-up pump and mixer needs to be provided for each press color station.

Finally, if an existing press does not have such apparatus, to add the make-up pump and mixer for each of its color stations is a costly, and cumbersome task. However, without it, such an existing press cannot be used with inks that require the controlled injection of make-up fluid on press.

Instead, what is needed in the art is a small footprint, disposable, low-cost method for fluid injection that can be added to any existing press, thus solving the problems of the prior art. SUMMARY OF THE INVENTION:

Systems and methods for the injection of make-up fluid into a printing press without the need of an injection pump or a mechanism for stirring in the injected fluid are presented. In exemplary embodiments of the present invention, make- up fluid can be injected into any type of ink being circulated by an ink pump to a press color station under continuous operation for the purpose of maintaining the ink in a state of constant, or within a certain defined range of, rheology and surface tension. In exemplary embodiments of the present invention, the makeup fluid can be stored in a reservoir, and the output of the reservoir provided with a valve. Downstream of the valve can be a make-up fluid injection nozzle, arranged to inject make-up fluid into an ink line. The make-up fluid flow can be, for example, gravity-assisted, or for example, can be injected into the ink line, or both. In exemplary embodiments of the present invention, a partial vacuum can be created in the ink line, and the make-up fluid injected at a region of negative pressure associated with the partial vacuum. In exemplary embodiments of the present invention, the valve can be a proportional solenoid valve, and can be automatically controlled by a controller, where the controller is driven by a signal coming from a sensor provided in an ink line or sump. In exemplary embodiments of the present invention, the sensor can measure the pH, viscosity, water content, impedance or conductivity of the ink, for example, and the controller can be set to open the valve as make-up fluid is needed. Thus, in exemplary embodiments of the present invention (i) a separate make-up fluid pump can be obviated and/or (ii) a mechanical ink mixer can be removed, by exploiting the negative pressure in the ink intake line generated by the existing ink pump and the turbulence that follows the sudden increase in pressure following a constriction in the ink feed line. The inventive apparatus thus involves a small and portable device that can be used as an add-on to existing presses, regardless of size, or, for example, can be provided with new presses. In exemplary embodiments of the present invention, a portion of the ink inlet line containing the make-up fluid nozzle can be sold as a removable disposable part. Additionally, for example, such a disposable apparatus could be sold together with a prefilled bag of make-up fluid, as a single disposable kit.

BRIEF DESCRIPTION OF THE DRAWINGS:

Fig. 1 depicts an exemplary gravity-fed, vacuum-assisted, make-up fluid injection system for a pumped ink according to an exemplary embodiment of the present invention; Fig. 2 depicts a generic diagram of an exemplary ejector to illustrate the essentials of inline mixing according to an exemplary embodiment of the present invention; and

Fig. 3 depicts an exemplary pump inlet line (horizontal line region) at a lower pressure than a pump outlet (diagonal line region) due to a constriction between them according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION:

As noted, conventional injection systems for ink maintenance all include a pump mechanism for the make-up fluid governed by the output of a sensor. This invention replaces this pump with a simple valve and utilizes the draw of the ink feed pump to pull in the make-up fluid as a result of the existing negative pressure provided by the ink pump. Depending on the position of fluid injection, commercial injection systems also include mixers to blend the injected liquid with the ink. In another exemplary embodiment, this invention replaces this mixing operation by injecting the make-up fluid directly into the ink flow where by combination of constrictions followed by expansions, sufficient mixing occurs. The inventive device's simplicity preferably with no moving parts is technically easier to control and maintain, is lower cost, and has a smaller footprint (physical size) than current commercial units. These advantages become more significant when they are utilized in multiple print stations. Since each ink station requires a make-up system, eliminating the make-up pump and the mixer is a considerable savings in capital and space. Fluid injection control can be, for example, as simple as a shutoff valve or clamp and a narrow inside diameter needle inserted into the ink feed line in front of the ink pump.

Thus, the design and use of a simple apparatus for injection of make-up fluid into any type of ink being circulated by an ink pump to a press color station under continuous operation is described for the purpose of maintaining the ink in a constant rheological and surface tension state. The present invention obviates the need for a make-up fluid pump by exploiting a negative pressure in the ink intake line that is generated by the existing ink pump to both incorporate the make-up fluid and cause it to mix with the ink, thus allowing removal of a mechanical ink mixer as well.

Described herein is an apparatus for the injection of make-up fluid into a pumped ink during the operation of the press. In its simplest form, it can be comprised of an atmospheric pressure make-up liquid reservoir, a connecting tube in which is installed an on/off valve, and a narrow diameter needle that is inserted into the feed line to the ink pump. In its most complex form, it can comprise a valve whose rate of delivery from the make-up fluid reservoir is controlled by the output of at least one sensor in either the ink reservoir (sump) or in the ink return line. The invention is based upon the recognition that the negative pressure in the ink feed line ahead (upstream) of the ink pump can draw in a flow of liquid from a narrow diameter delivery line inserted into the ink pump feed line. Previously, such devices required a sensor-driven make-up fluid pump, either air driven or electrical. The construction of the injector can also provide mixing. By forcing the ink flow following injection through a constriction (converging nozzle) followed by an expansion (diverging diffuser), mixing of the two flows occurs. It is noted that the notion of fluid injectors with no moving parts dates back to 1858 and H. Giffard, as provided in S. L. Kneass, Practice and Theory of the Injector, John Wiley and Sons (originally printed in 1894, reprinted in 2007 by Kessinger). As provided therein, the flow of one liquid can impart velocity to droplets of a second, and a series of velocity increases by flow constriction followed by velocity drops by flow expansion can serve to mix both flows. However, to date, no application of this technology to the delivery of controlled composition ink to a press is known. Control of ink composition by viscosity or pH feedback to a pump that injects a fluid into a printing ink is widely employed to assure optimum ink rheology. In gravure or flexographic printing, this fluid is most commonly a volatile solvent. In single-fluid lithography, it is commonly fountain solution in water. This fluid injection function is often combined with an ink pumping station to give a package that is comprised of an ink reservoir (sump), an ink pump, a make-up fluid reservoir, a make-up fluid pump, the make-up fluid pump electronics, a solenoid valve, a sensor, the sensor's electronics, a check valve, and a mixer. All-combined, the unit occupies nearly six square feet of floor space (footprint) which must be repeated as many times as there are ink stations on the press. The cost of such an installation is a considerable investment for the printer or the ink supplier.

The present invention addresses the cost and the footprint of such a device by elimination of the make-up fluid pump and/or its electronics and/or the mixer. The opportunity to do so comes from the realization that the ink pump creates a vacuum that can be used to draw liquid through a narrow feed line inserted into the pump intake line. It is even possible that in some circumstances the valve may be a simple on/off function and the make-up flow be controlled by the inside diameter of the make-up fluid feed line inserted into the ink pump intake line. Fig. 1 depicts an example of a gravity-fed, vacuum-assisted, make-up fluid injection system for a pumped ink according to an exemplary embodiment of the present invention. With reference thereto, make-up fluid resides in fluid reservoir 100, and a flow meter 1 15 inputs a flow rate to a controller 120, which controls the flow of the make-up fluid out of the reservoir and into the printing press. Controller 120 also receives a signal from a viscosity, pH, conductivity, dielectric, or other sensor (meter), placed upstream from the fluid injection needle (not shown in Fig. 1 , but would be to the left of Fluid Injection needle 140 in the ink intake line, or, for example, in the ink sump). Controller 120 operates a solenoid valve 125, which can be, for example, either simple or proportional. A check valve 130 prevents ink backing up to the valve. A fluid injection needle 140 is placed in the intake line to ink pump 150 which feeds ink to the press.

The fluid reservoir is preferably at atmospheric pressure, either from a vent in a hard container or by use of a collapsible container (similar in function to a hospital IV bag). In the ink pump intake, the ink will preferably be at less than atmospheric pressure so that a pressure differential will exist (a partial vacuum). This vacuum will assist fluid flow through a narrow orifice such as a stainless steel tube inserted into the ink intake line. Shear forces can then mix the ink and the makeup fluid either in the pump, and/or in a doctor bladed chamber that feeds the engraved cylinder of a flexographic or gravure press, and/or in a roller train of a lithographic press. If additional mixing is required, this can optionally be achieved by the well known static mixers that separate and blend fluid flows. Such static mixers can, for example, be inserted into the ink feed line after the injector and either before or after the ink pump.

In exemplary embodiments of the present invention, mixing can also occur due to the principles governing an aspirator, as next described with reference to Fig. 2. Fig. 2, a generic diagram of an exemplary ejector, shows an exemplary embodiment of the present invention where such mixing is accomplished. With reference thereto, Fig. 2 illustrates the essentials of (i) the inline mixing that occurs following a draw of make-up fluid 210 from a make-up nozzle 220 due to the negative pressure provided by the flowing ink, (ii) the constriction and rise in pressure that occurs either in the ink pump (peristaltic) or by other constriction in the ink line, and (iii) the pressure drop caused by expansion following the ink pump or by an increase in hose diameter or other means. In exemplary embodiments of the present invention the constriction can be placed, for example, either ahead, or following, the ink pump.

Continuing with reference to Fig. 2, make-up fluid 210 can, for example, be drawn into the ink flow through the make-up fluid nozzle 220. The negative pressure created by the flowing ink thus assists the make-up liquid flow, and thus eliminating the need for a pressure head on the make-up fluid, such as, for example, provided by gravity as in the exemplary embodiment of Fig. 1 . In exemplary embodiments of the present invention, either as a part of the pumping operation (peristaltic), or inserted into the ink flow following injection, there can be, for example, a constriction where the velocity rises, such as the converging inlet nozzle 240. Following this point the velocity falls at a diverging outlet 270. Such sudden rising and lowering of velocity causes turbulence which can mix the fluid by shearing forces, as discussed, for example, in U.S. Patent Nos. 4,860,959 and 4,186,772, and illustrated in Fig. 3.

Fig. 3 depicts an exemplary pump inlet line (the region at the left covered in horizontal lines) at a lower pressure than a pump outlet (the region at the right covered in diagonal lines). The constriction 315 imparts a localized increase in the negative pressure in the inlet line (i.e., in the white (non-hatched) region in between the horizontal line and diagonal line regions). Thus, there is a pressure decrease 310 leading up to the constriction 315, and a pressure increase 320 following it. Using the partial vacuum created by the constriction shown in Fig. 3, in exemplary embodiments of the present invention a make-up fluid nozzle can be placed anywhere in the lower pressure horizontal line region 310 where a partial vacuum already exists, or, for example, for an even larger vacuum it can be placed in the constricted (non-hatched) region 315. Due to the partial vacuum, the make-up fluid will thus be drawn into the ink flow 350, again without the need for a make-up injection pump or stirrers. In exemplary embodiments of the present invention an increase in vacuum caused by the constriction can be implemented where the make-up fluid is viscous or an ink pump does not generate enough partial vacuum to draw the make-up fluid without assistance. The partial vacuum can be increased, for example, by increasing the constriction 315, or by placing the injection nozzle into region 315, for example.

In exemplary embodiments of the present invention, the make-up nozzle 220 (or the fluid injection needle 140 in Fig. 1 ) can have a diameter that narrows at its distal end, so as to so as to inject the make-up fluid into the ink intake line. So as to further facilitate mixing of the make-up fluid into the ink, such a nozzle or needle can have, for example, a diameter somewhat less than, for example, that of the ink intake line itself, as shown, for example, in Figs. 2 and 3. For example, the nozzle can have a distal diameter that is, for example, less than 1 /10 ^th that of the ink intake line. Or, as may be appropriate, even smaller distal diameters may be appropriate, such as less than 1 /15 ^th , or even less than 1/20 ^th of the diameter of the ink intake line. In general such sizing depends upon a number of factors, and can be optimized for various presses. Such factors can include, for example, the ink pump rate the size of the ink intake line, the viscosity of the ink and the makeup fluid, the vacuum created, and the flow of makeup fluid that is required to compensate a variable evaporation rate.

In exemplary embodiments of the present invention, as shown in Fig. 1 , a proportional type solenoid valve (for example, 0% voltage, no flow; 100% voltage, maximum flow; 50% voltage, half flow) can, for example, be included to receive a voltage signal indirectly from a sensor that resides in the ink return line or sump. Such a voltage signal can be used, for example, to open or close the valve. This signal can be, for example, generated by the sensor's electronics according to the upper and lower limit set points on the sensor, and can, for example, be used by a programmable logic controller ("PLC"), or other such controller, to create the proper voltage for the solenoid.

In exemplary embodiments of the present invention, as a further refinement, a flow meter output could optionally be used to ramp up the flow as demand increases. Thus, in such exemplary embodiments, a control algorithm would also specify a flow rate designed to keep up with the loss of make-up fluid, and the controller would thus control both the valve 125 and such a flow meter 1 15, as shown in Fig. 1 . Alternatively, for example, a simple open/closed valve can be employed with an adjustable needle valve located downstream to control the flow rate of the make-up liquid. And most simply, the flow can be either on or off and the rate can be set by the inside diameter of the make-up fluid line inserted into the ink feed pump intake line. In exemplary embodiments of the present invention, as shown in the embodiment of Fig. 1 , a check valve can complete the unit, preventing ink backflow into the fluid make-up line.

Besides a PLC, in exemplary embodiments of the present invention other types of controllers can be used as well. In exemplary embodiments of the present invention, a controller can automatically set the flow rate, or, for example, an operator can set and maintain the water flow by use of a manual value. In exemplary embodiments of the present invention such an automatic valve can be proportional or operate in a simple on/off configuration. In exemplary embodiments of the present invention the manual valve can be adjustable, on/off, or a pinch valve similar to the type used in IV bags.

In exemplary embodiments of the present invention, each line can, for example, have its own fluid, or a single fluid reservoir can service more than one make-up line through a manifold system. The savings of omitting, for example, six or more pumps and six or more mixers (such as, for example, is needed in a printing press having color stations for CMYK and two spot colors), the convenience of a collapsible container and gravity feed, and the ability to add this system to any current ink pumping station is a considerable advantage vs. current installations, which have larger footprint and may require air lines for operation.

It is noted that where the make-up nozzle (or fluid injection needle) empties into an ink line, after running on-press for a significant time period, the nozzle, given its small diameter, may become clogged with make-up fluid or ink and thus would need to be cleaned prior to another use. Such a cleaning task may be undesirable for printing press operators (multiplied by, for example, six stations) , and the costs of a small section of ink line with a make-up fluid nozzle provided therein is small. Thus, in exemplary embodiments of the present invention, a portion of the ink inlet line containing the make-up fluid nozzle can be sold as a removable disposable part. This would be the portion of ink line at the far left of Fig. 2, with the make-up nozzle. Additionally, for example, such a disposable apparatus could be sold together with a prefilled bag of make-up fluid, as a single disposable kit. Once the make-up fluid is used up, the bag, length of pipe and make-up nozzle can be discarded, and a new kit can be installed in the ink inlet line. The remaining components, such as a sensor, controller, flow meter, etc. can be permanent, for example, and located outside of the disposable line of pipe or tube.

The present invention has been described in detail, including various exemplary embodiments thereof. However, it will be appreciated that those skilled in the art, upon consideration of the present disclosure, may make modifications and/or improvements on this invention that fall within the scope and spirit of the invention