NOZZLE APPARATUS FOR DISPENSING COLORANT

Abstract

A nozzle apparatus is described in relation to dispensing colorant liquid in a paint tinting system. The nozzle apparatus comprises: a nozzle (12, 13) with a passage (14, 15) for a colorant liquid (16), the passage (14, 15) extending to an outlet for dispensing colorant liquid from the nozzle (12, 13); and an ultrasound transducer (20) for applying ultrasonic vibration to the nozzle (12, 13) and/or to liquid (16) at the nozzle outlet.

Claims

1. A nozzle apparatus for dispensing colorant liquid in a paint tinting system, the nozzle apparatus comprising: a nozzle with a passage for a colorant liquid, the passage extending to an outlet for dispensing colorant liquid from the nozzle; and an ultrasound transducer for applying ultrasonic vibration to the nozzle and/or to liquid at the nozzle outlet.

2. A nozzle apparatus as claimed in claim 1, wherein the nozzle apparatus is arranged such that after a liquid is passed through the nozzle duct and the flow of liquid is stopped then ultrasonic vibration is applied to detach any remaining liquid from the nozzle outlet.

3. A nozzle apparatus as claimed in claim 1 or 2, including a controller for controlling the flow of liquid as well as for controlling the ultrasound transducer, wherein the controller is arranged such that the ultrasonic vibration is applied after a liquid is passed through the nozzle duct and when the flow of liquid has stopped.

4. A nozzle apparatus as claimed in any preceding claim, comprising an ultrasound horn that is separate to the nozzle, wherein the ultrasonic vibration is applied to the liquid at the outlet of the nozzle using the ultrasound horn that is separate to the nozzle, and wherein an end of the ultrasound horn is positioned or positionable adjacent the outlet of the nozzle in order to bring it into contact with any colorant liquid that may be retained at the nozzle outlet.

5. A nozzle apparatus as claimed in any of claims 1 to 3, wherein the ultrasonic vibration is transmitted from the ultrasound transducer through the nozzle and the nozzle acts as an ultrasound amplifier.

6. A nozzle apparatus as claimed in claim 5, wherein the nozzle comprises a titanium alloy or an aluminium alloy.

7. A nozzle apparatus as claimed in claim 5 or 6, wherein the passage has an inlet located at a node in the vibration pattern of the nozzle.

8. A nozzle apparatus as claimed in claim 8, wherein the passage extends in a first passage portion from the outlet at a tip of the nozzle along a centre-line of the nozzle until the node point, and then the passage turns to extend in a second passage portion that is perpendicular to the centre-line and connects to the inlet at the surface of the nozzle.

9. A nozzle apparatus as claimed in any preceding claim, wherein the apparatus is arranged to apply ultrasonic vibrations with a varying amplitude.

10. A nozzle apparatus as claimed in any preceding claim, wherein the ultrasound transducer vibrates at a frequency in the range 20 kHz to 120 kHz, the peak amplitude of the vibration at the ultrasound transducer is in the range 0.1 to 12 um and the peak amplitude of the vibration at applied to the nozzle outlet and/or the liquid at the nozzle outlet is amplified compared to the peak amplitude of the vibration at the ultrasound transducer and is in the range 1 to 120 um.

11. A nozzle apparatus as claimed in any preceding claim, wherein the passage in the nozzle has a diameter of 1-4 mm and optionally, wherein the largest cross-section through the width of the nozzle has a maximum dimension in the range 8-52 mm.

12. A nozzle apparatus as claimed in any preceding claim, wherein the nozzle apparatus is arranged to operate a cleaning cycle including applying ultrasonic vibrations to the nozzle and/or to cleaning liquid in contact with the nozzle, and optionally wherein the nozzle apparatus comprises a reservoir of cleaning liquid as a part of a cleaning system used in the cleaning cycle.

13. A nozzle apparatus as claimed in claim 12, wherein the nozzle apparatus is configured such that during the cleaning cycle the nozzle is dipped into a container of cleaning liquid and ultrasonic vibrations are applied.

14. A nozzle apparatus as claimed in claim 13 or 14, wherein the nozzle apparatus is configured such that during the cleaning cycle a cleaning liquid is passed along the passage of the nozzle and ultrasonic vibrations are applied whilst the cleaning liquid is flowing through the passage and/or after flow of the cleaning liquid is stopped.

15. A paint tinting system including a nozzle apparatus as claimed in any preceding claim.

16. A paint tinting system as claimed in claim 15, comprising: multiple nozzles, wherein each nozzle is coupled to an ultrasound transducer for vibrating the nozzle; and an ultrasound generator arranged to provide an electrical signal to several ultrasound transducers.

17. A method for use of a nozzle apparatus in dispensing colorant liquid, the nozzle apparatus comprising: a nozzle with a passage for a colorant liquid, the passage extending to an outlet for dispensing colorant liquid from the nozzle; and an ultrasound transducer; and the method comprising applying ultrasonic vibration to the nozzle and/or to liquid at the nozzle outlet.

18. A method as claimed in claim 17, the method comprising applying the ultrasonic vibration after a colorant liquid is passed through the nozzle duct and when the flow of colorant liquid has stopped, wherein the ultrasonic vibration is applied for the purpose of detaching any colorant liquid that has been retained at the nozzle outlet.

19. A method as claimed in claim 17 or 18, including cleaning the nozzle by exposing it to a cleaning liquid and using ultrasonic vibration to enhance the effect of the cleaning liquid.

20. A computer programme product for a controller of a nozzle apparatus as claimed in any of claims 1 to 14, wherein the computer programme product comprises instructions that, when executed, will configure the controller to: control dispensing of colorant liquid; and control the ultrasound transducer in order to apply ultrasonic vibrations to the nozzle and/or to liquid at the outlet of the nozzle to detach colorant liquid that has been retained at the nozzle outlet.

Description

[0039] Certain preferred embodiments will now be described by way of example only and with reference to the accompanying drawings, in which

[0040] FIG. 1 shows a nozzle apparatus with a nozzle and a separate ultrasound horn;

[0041] FIG. 2 shows a nozzle apparatus where the nozzle is adapted to also transmit ultrasonic vibrations; and

[0042] FIG. 3 is a cross-section of a nozzle for use in the apparatus of FIG. 2.

[0043] The preferred embodiments relate to nozzles for dispensing colorant in a paint tinting system. Such a system will typically include multiple nozzles that allow for one or more of multiple different colorants to be dispensed into a base paint in order to transform the base paint into a tinted paint with desired colour characteristics. As discussed above, it is important to ensure that the colorant is dispensed accurately and in particular to avoid retention of unknown amounts of colorant at the nozzle tip. It is also important to keep the nozzle tip clean of colorant to avoid problems caused by dried colorant at the nozzle tip and the outlet for colorant liquid, such as blockages and contamination of paint with dried colorant. Thus, it is proposed to clean the nozzle tip after each use of the nozzle to dispense colorant through the use of a nozzle apparatus including the nozzle as well as an ultrasound transducer.

[0044] Two possible implementations for an ultrasound based nozzle cleaning system are shown in FIGS. 1 and 2. In FIG. 1 ultrasound is applied to colorant liquid retained at the nozzle tip by using a separate ultrasound horn that is positioned adjacent the nozzle tip. In FIG. 2 ultrasound is applied via the nozzle itself. Either alternative could be adapted for use in a paint tinting system using multiple nozzles to dispense different types of colorants in order to provide customisable paint colours. For example, they might be implemented in paint tinting systems as sold by Jotun A/S under the trade name Multicolor.

[0045] With reference to FIG. 1, a nozzle 12 has a passage 14 for a colorant liquid 16. The passage 14 extends to an outlet which in this case is at the tip 18 of the nozzle 12. This nozzle 12 may be a generally standard shape and form although it made be adapted by a change of the material in order to withstand ultrasound transmitted into the nozzle by the liquid 16. For example, an aluminium or titanium alloy may be used in place of the usual stainless steel. In use, when flow of the colorant liquid 16 has been stopped then a droplet of the liquid 16 may remain at the tip 18 of the nozzle 12. In order to detach any remaining droplet of colorant liquid 16 an ultrasound horn 20 is placed adjacent to the nozzle tip 18 and this is used to apply vibration to the liquid 16 at ultrasonic frequencies. The ultrasound horn 20 may always be located as shown, or alternatively it may be actuated to move toward and away from the tip 18 so as to avoid any obstacle to colorant liquid 16 being dispensed from the outlet of the nozzle 12 during normal use. The ultrasound horn 20 is coupled to an ultrasound transducer 22 and may vibrate with frequencies and/or amplitudes similar to those discussed below in relation to the embodiment shown in FIG. 2.

[0046] In the alternative arrangement of FIG. 2 an adapted colorant dispensing nozzle 13 is used both to dispense colorant liquid 16 and also to transmit and amplify ultrasonic vibrations to detach unwanted remaining liquid 16 from the outlet at the tip 18 of the nozzle 13. The adapted nozzle 13 includes a passage 15 for a colorant liquid 16, which is adapted with reference to the ultrasonic vibration of the nozzle 13 as explained below. As the adapted nozzle 13 also acts as an ultrasound horn then it is coupled directly to the ultrasound transducer 22 via a bolt 24. The adapted nozzle 13 is also shaped to act as an ultrasound booster. This is shown schematically in FIG. 2, and one example of an adapted nozzle 13 shown to scale is found in FIG. 3, which shows a cross-section of a nozzle 13 that is designed to be attached to an ultrasound transducer 22 and to transmit and amplify ultrasonic vibrations. It has been found that transmitting the vibrations via the nozzle 13 can be more effective at detaching retained droplets of colorant liquid 16 from the tip 18 than using a separate ultrasound horn 20 as in FIG. 1.

[0047] FIG. 3 shows a cross-section of an adapted nozzle 13 that is designed to be attached to an ultrasound transducer 22. The nozzle 13 includes a passage 15 for colorant liquid 16. The passage 15 extends longitudinally along a centreline of the nozzle 13 from an outlet at the tip 18 to a turn point 26 where the passage 15 turns a right angle and then extends radially to an inlet port 28 at the side of the nozzle 13. The port 28 allows for onward connection to tubing or similar for coupling the passage 15 to a source of colorant liquid. The turn point 26, the port 28 and the radial part of the passage 15 are located at a node of the vibrational pattern of the adapted nozzle 13. Thus, they are at all located in a region that experiences minimum (or zero) movement whilst the nozzle 13 is being vibrated. This means that there is no undue movement or stress on the port 28 or the connections at the port 28. It also allows for reductions in stress concentrations in the material of the nozzle 13 arising from vibrational movements of the material around the passage 15. As shown in FIG. 3 the nozzle 13 includes a threaded hole 30 to enable it to be joined to an ultrasound transducer 20 with a bolt 24 in a similar way to the nozzle 13 of the schematic view of FIG. 2.

[0048] During use of the nozzle apparatus a colorant liquid 16 is passed through the passage 14, 15 and dispensed into a base paint. This can be in the context of any suitable paint tinting system. When the flow of colorant liquid 16 is stopped then the ultrasound transducer 20 is activated and ultrasonic vibration is transmitted either as shown in FIG. 1, directly to the liquid 16 at the tip 18 of the nozzle 12, or as shown in FIG. 2, through the adapted nozzle 13 to the tip 18 and hence to any colorant liquid 16 retained at the tip 18. As a result of the ultrasonic vibration any droplet of colorant liquid 16 that is retained at the tip 18 is detached from the tip 18 and falls into the paint.

[0049] This has various advantages. The amount of colorant liquid 16 that can be dispensed can be more accurately known and controlled, since there is no longer any uncertainty about whether or not a droplet of liquid will remain attached to the nozzle tip 18 once the flow of liquid has stopped. Liquid may also detach from within the passage 14, 15 inside the nozzle 12, 13, especially in the case of the adapted nozzle 13 where the whole nozzle 13 is vibrated by the ultrasound transducer. The risk of build-up of dried colorant liquid at the nozzle tip 18 and within the end of the passage 14, 15 is reduced since the colorant liquid is detached, and where the colorant liquid is also detached from the inside of the passage 14, 15 then this benefit arises for some distance within the passage 14, 15 as well.

[0050] The ultrasound vibration can be applied at a frequency suited to the design and size of the nozzle 13 or the ultrasound horn 20. Known types of ultrasound transducer 20 can be used to provide such vibrations. It is expected that frequencies of between 30 kHz to 120 kHz may be used, such as a frequency of about 100 kHz for a smaller sized nozzle, or a frequency of about 55 kHz for a larger sized nozzle. The amplitude of the ultrasound vibration may be about 50 m at the tip 18, amplified from perhaps 5 m at the ultrasound transducer 22. In some examples the amplitude of the vibrations is varied, for example it may be cycled through an amplitude from 30 m to 80 m at the tip 18. As explained above varying amplitude can allow for a single set-up for the nozzle apparatus to be used for colorant liquids of varying properties, such as varying density and or viscosity.

[0051] The ultrasound transducer 22 receives an electrical signal from a suitable ultrasound generator. In the case of a paint tinting system with multiple nozzles 12, 13 then each nozzle 12, 13 can have its own ultrasound transducer 22 with a common ultrasound generator being electrically connected to all of the transducers 22. It will be appreciated that in such a paint tinting system then colorant will be dispensed separately from the various nozzles and thus that the ultrasound can be applied separately and at different times. This means that the ultrasound generator need only ever operate a small number of transducers at any one time, perhaps only a single transducer at a time, and therefore it is efficient to have only a single ultrasound generator for the whole system.

[0052] A paint tinting system using the proposed nozzle apparatus would include a plurality of sources of colorant liquids, each of which may include a reservoir and a pumping system for supplying each colorant liquid 16 to a respective nozzle 12, 13. A metering system of known type could also be included. This metering system can be calibrated with measurements including the use of ultrasound to detach retained colorant liquid 16 from the nozzle top 18, which allows for accurate and repeatable dispensing of colorant liquid 16 even when small quantities are needed. The nozzles and associated liquid distribution systems can be mounted on a carousel or other suitable arrangement for aligning the required nozzle with a container of a base paint for dispensing of colorant into the base paint. Other features of such paint tinting systems as are known in the prior art may also be present.

[0053] In addition to the use of ultrasonic vibration to detach colorant liquid 16 from the nozzle tip 18 the nozzle apparatus may also be arranged to use ultrasound to enhance cleansing of the nozzle 12, 13 during maintenance or as a part of an automated cleaning cycle. With this feature a cleaning liquid may be used, for example this could be water in the case of water soluble/water-based colorant liquids. The nozzle 12, 13, or parts of the nozzle 12, 13 such as the passage 14, 15 or the tip 18 may be placed into contact with the cleaning liquid and ultrasonic vibration may be used to detach any contaminants, such as dried colorant, from surfaces of the nozzle 12, 13.

[0054] Thus, in one example the nozzle 12, 13 can be dipped in to a container of cleaning liquid with the tip 18 submerged. The cleaning liquid can then be vibrated via the ultrasound horn 20, or the nozzle 13 can be vibrated with the tip 18 submerged. This will detach contaminants such as dried colorant or dirt of other types from the tip 18 as well as from the interior of the passage 14, 15 adjacent the tip 18. Another possibility is to flow cleaning liquid through the passage 14, 15 and to subject the nozzle to ultrasound vibration whilst the passage 14, 15 is full of cleaning liquid. It is expected that this may be more effective with vibration of the adapted nozzle 13 rather than with vibration from an external ultrasound horn 20, since the walls of the passage 15 in the adapted nozzle 13 it may be difficult for vibrations to propagate into the passage 14.