Patent Description:
<CIT> discloses an example of such an apparatus.

<CIT> relates to a valve assembly for a fluid dispenser, which includes a housing having at least a first opening and a second opening, a valve member fitted in the housing, the valve member being rotatable about an axis and comprising a first channel, extending along said axis and communicating with the first opening in the housing, and at least two outlet channels radially extending from the first channel to the circumference of the valve member, wherein each of the radially extending outlet channels can be brought in register with the second opening by rotating the valve member.

<CIT> relates to a method of homogenizing a liquid, in particular a colorant for paint, in a container, comprising the steps of withdrawing liquid from the container at a first flow speed (SI) and then returning the liquid to the container at a second flow speed (S2), higher than the first flow speed (SI).

In colorant dispensers for paint, purging, i.e. dispensing a small amount of colorant to clean the dispense opening and thus reduce the risk of so-called mistints resulting from nozzle blockage e.g. caused by colorant drying in the dispense opening, is a common and effective practice, as for example is disclosed in <CIT>. However, purging implies waste of colorant.

It is an object of the present invention to provide effective cleaning of the dispense opening and yet reduce or prevent such waste.

The invention relates to an apparatus according to claim <NUM>.

In an embodiment, each one of the assemblies comprises at least one further dispense opening, e.g., having a diameter different from the diameter of the first dispense opening, e.g. smaller to allow more accurate dispensing or larger to allow faster dispensing, and wherein the controller is arranged to operate the pump and the valve to purge liquid from the pump to the container via the at least one further dispense opening, preferably via all dispense openings in succession. In another embodiment, the valve, in a first position, connects the container to the pump and, in a second or further position, connects the pump to the at least one dispense opening.

In a further embodiment, the valve comprises a rotatable valve member, e.g. a valve ball, cylinder or disc, and the dispense opening or openings is respectively are defined in the valve member, e.g. as a channel or channels that extends respectively extend radially or axially in the valve member. Thus, the liquid is dispensed directly from the valve member, e.g. through a larger opening in the valve, e.g. in the housing of the valve, preferably preventing the liquid from contacting the larger opening.

With the present invention the dispense opening can be cleaned by the purging with colorant itself and yet, because the purged colorant is returned to the container, waste is reduced or prevented altogether.

In a refinement, the openings are all located within <NUM>°, preferably within <NUM>°, of rotation of the valve member from each other. Thus, total rotation required to purge all openings is limited and operation facilitated.

The controller can be, e.g., positioned at a dispense position and coupled with the other parts when these are at the dispense position.

According to the invention, in a position of the valve, at least the pump is closed and the controller is arranged to establish, preferably by measuring the compressibility or expandability of the medium e.g. by measuring resistance in or stroke of the pump, whether and, if so, to what extent the medium contains air. In a refinement, in a position of the valve, all suction and dispense openings and routes are closed.

If the liquid inside the pump allows more compression or expansion than the liquid as such, this is an indication that the liquid contains air. The liquid may contain air as a result of e.g. production or mixing of the liquid or of an empty container, refilling of a container, or a leaking seal in the assembly. The degree of displacement provides an indication of the root cause. Pump condition and/or container filling status can be registered and communicated to the operator and/or service representative e.g. by means of signals and/or a log.

In a further embodiment, the valve comprises a variable opening and/or a plurality of different openings and the controller is arranged to establish whether flow resistance in the liquid over the opening. This can be achieved e.g. by accurately controlling the valve and/or shaping the openings, e.g. oval, diamond or oblong, to vary overlap between internal openings and/or providing two or more channels having different diameters and/or different effective cross-sections and thus set flow resistance.

This provides a means for determining the condition of the liquid, e.g. by measuring flow resistance from the control of motor driving the pump, e.g., at different openings or overlaps. Overlap and/or shape and/or surface and/or length (in flow direction) of the opening will affect the shear in the liquid and, e.g., for shear thinning and/or shear thickening liquids this will provide information whether a certain viscosity yield value is still present, which can serve as an indication of the condition of the liquid.

Measurements of (parameters indicative of) compressibility, expandability or flow resistance can be performed automatically, e.g. periodically and/or outside business hours, and a signal generated to inform an operator or service representative.

In another embodiment, the controller is arranged to purge the dispense opening (s) and perform said measurements automatically, e.g. periodically and/or outside business hours.

In a further embodiment, the pump is a positive displacement pump, preferably a reciprocating pump, preferably a piston pump.

The apparatus of the invention can be used for dispensing a liquid, in particular a colorant for paint, from the assemblies, comprising the steps of withdrawing liquid from the container and dispense the liquid from the dispense opening, and characterised by purging liquid from the pump to the container via the dispense opening. In an embodiment, the assembly comprises a further dispense opening, wherein liquid is purged from the pump to the container via the further dispense opening.

In another embodiment, the pump is closed by means of the valve and the degree of compressibility or expandability of the liquid in the pump is established.

Optionally, use of the apparatus comprises varying an opening, e.g. between the pump and the container, generating a flow of the liquid through different openings and establishing flow resistance in the liquid over the different openings.

Within the framework of the present invention the term "liquid" is defined as any flowable material that comprises a liquid phase and thus includes suspensions and emulsions. Colorants often contain a high density of pigments or particles suspended in (instable) liquid binder/solvent solutions.

The disclosed invention will be further explained with reference to the accompanying drawings in which presently preferred embodiments of the invention are shown schematically.

<FIG> illustrates the main parts of an example of an apparatus <NUM> for dispensing colorants or dyes. This particular dispensing apparatus includes a turntable <NUM> rotatable about a vertical axis by means of a drive (not shown) in order to rotate the turntable <NUM> between discrete positions. On the turntable <NUM>, there are mounted a plurality of assemblies <NUM>, each comprising a container <NUM> for holding a liquid, pump <NUM>, and a valve <NUM>. Further details of the said apparatus and turntable are disclosed in <CIT>.

<FIG> show cross-sections of the pump <NUM> and valve <NUM>. The pump <NUM> is a piston pump and includes a piston rod 5A provided with a piston 5B, disposed within a cylinder 5C of the pump <NUM>, and an upper flange 5D. The flange 5D can be engaged by a controller <NUM> comprising an actuator (not shown) adapted to move the piston rod 5A and the piston 5B upwards during an intake stroke and downwards during a dispense stroke and an actuator (not shown) to operate the valve <NUM>.

The controller <NUM> and actuators are stationary and arranged to position one of the assemblies <NUM> in line with the actuators in order to enable actuating the pump <NUM> and the valve <NUM>. The cylinder 5C is mounted in the top part of a pump housing <NUM>, which defines a cavity <NUM> and further includes an inlet channel <NUM> that is separated from the cavity <NUM> and adapted to be in fluid communication with a container <NUM> as shown in <FIG>.

A valve housing <NUM>, comprising a cover 12A, is attached to the lower part of the pump housing <NUM> by means of respective flanges <NUM>, <NUM>. A valve member, in this example a ball <NUM>, is fitted in the housing <NUM> by means of two annular bearings 16A, 16B made of, e.g., a polymeric material, such as PTFE (Teflon). The valve member <NUM> is provided with a lever <NUM> with which it can be rotated about an axis A by means of the corresponding actuator. The valve housing <NUM> further defines a cavity <NUM> limited at its upper part by a first opening <NUM>, through which the cavity <NUM> communicates with the cavity <NUM> of the pump housing <NUM>. The valve housing <NUM> further includes a second opening <NUM> in its bottom part and a third opening <NUM> which communicates with the inlet channel <NUM> in the pump housing <NUM>. The valve member <NUM> includes a first channel <NUM>, extending along the axis A and communicating with the first opening <NUM> in the housing <NUM>. It further includes at least two dispense openings, in this example in the form of outlet channels <NUM>, <NUM>, and an inlet channel <NUM>, all radially extending from the first channel <NUM> to the circumference of the valve member <NUM>. In this particular embodiment, the diameter of one of the outlet channels <NUM> is smaller than that of the other <NUM> and the diameter of both outlet channels <NUM>, <NUM> is smaller than that of the inlet channel <NUM>. Further, both of these diameters are smaller than the diameter of the outlet opening <NUM> in the housing <NUM> and the central axes of channels <NUM>-<NUM> are all located on the same sectional plane through the valve member <NUM> and are respectively, e.g., <NUM> and <NUM> apart.

<FIG> show the intake position of the valve member, where the inlet channel <NUM> of the valve member <NUM> is in registry with the third opening <NUM> of the valve housing <NUM> and thus with the inlet channel <NUM>. In other words, the container communicates with the cavity <NUM> in the pump housing <NUM> and the cylinder <NUM>. In this position, the cavity <NUM> and cylinder <NUM> now can be filled with a desired amount of the liquid from the container by moving the piston <NUM> upwards over a desired or predetermined length. It is noted that, in this position, the inlet channel <NUM> temporarily serves as an outlet channel.

As soon as an appropriate amount of liquid is taken in, the valve member <NUM> can be rotated to the desired dispensing position, i.e., until the desired dispense channel <NUM>, <NUM> is in register with the opening <NUM> in the housing and the piston <NUM> can be moved downwards to dispense a desired or predetermined amount from the said opening <NUM>. If this amount of liquid is relatively small and/or the dosage should be precise, the relatively narrow output channel <NUM> is appropriate and, if this amount is relatively large and/or should be dispensed rapidly, the relatively wide output channel <NUM> is appropriate. Thus, the valve assembly enables the tailored and, if need be, precise and/or rapid dispensing of viscous liquids, without having to exchange the valve assembly or components of the valve assembly.

During purging, shown in <FIG>, the valve member <NUM> is rotated until the desired dispense channel - the larger diameter channel in <FIG> and the smaller diameter channel in <FIG> - to be purged is in register with the third opening <NUM> in the housing <NUM>, which communicates with container <NUM>. In these positions, the piston <NUM> is moved downwards to purge a predetermined amount of liquid through the dispense channel back to the container <NUM>.

<FIG> shows a further embodiment of a valve according to the present invention in seven positions. In this embodiment, the radial dispense channels <NUM>, <NUM> are <NUM>° apart and the intake channel <NUM> is positioned in between the dispense channels. The positions are, in succession, intake or return of liquid via the intake channel <NUM>, purging the larger diameter dispense channel <NUM> by returning liquid to the container, purging the smaller diameter dispense channel <NUM> by returning liquid to the container, closing the pump from all suction and dispense openings and routes fluid, dispensing via the smaller diameter dispense channel <NUM>, dispensing via the larger diameter dispense channel <NUM>, and dispensing via the intake channel <NUM>.

Claim 1:
Apparatus (<NUM>) for dispensing colorants for paint, comprising a plurality of assemblies (<NUM>), each assembly comprising a container (<NUM>) for holding a liquid, a pump (<NUM>), a valve (<NUM>), at least one dispense opening (<NUM>, <NUM>), and comprising a controller (<NUM>) arranged to operate the pump (<NUM>) and the valve (<NUM>) to withdraw liquid from the container (<NUM>) and to dispense liquid via the dispense opening (<NUM>, <NUM>) and to operate the pump (<NUM>) and the valve (<NUM>) to purge liquid from the pump (<NUM>) to the container (<NUM>) via the dispense opening (<NUM>, <NUM>), characterized in that the valve (<NUM>), in a further position, closes at least the pump (<NUM>), wherein the controller (<NUM>) is arranged to establish whether the liquid inside the pump (<NUM>) is compressible or expandable.