Ultrasonic cleaning apparatus and method

Abstract

An ultrasonic cleaning apparatus and method, the ultrasonic cleaning apparatus (10) comprising a tank (12) for in use receiving a cleaning liquid and for receiving an item to be cleaned in a cleaning region (16) thereof, a transducer (21) arranged, when driven, to direct ultrasonic pressure waves into cleaning liquid received in the tank (12) and a controller (30) arranged in use to drive the transducer (21), a gas introducer (40) arranged to in use provide a supply of gas into cleaning liquid in the tank so that macroscopic bubbles of gas are produced wherein the gas introducer (40) provides a plurality of bubble sources distributed below the cleaning region of the tank. The apparatus further comprises an assembly arranged in use to enable movement of the item to be cleaned in the cleaning region.

Claims

1. An ultrasonic cleaning apparatus comprising: a tank for in use receiving a cleaning liquid and for receiving an item to be cleaned in a cleaning region thereof; a transducer arranged, when driven, to direct ultrasonic pressure waves into cleaning liquid received in the tank; a controller arranged in use to drive the transducer; and a gas introducer comprising a plurality of spaced apart conduits arranged around an inner diameter of the tank and extending inwardly therein, the plurality of spaced apart conduits configured to supply convergent gas streams into cleaning liquid in the tank so that macroscopic bubbles of gas are produced in the tank; wherein the ultrasonic cleaning apparatus comprises an assembly arranged to in use enable movement of the item to be cleaned in the cleaning region, wherein the apparatus comprises a liquid conduit arranged to in use deliver liquid towards the assembly to urge the assembly to move to further facilitate cleaning of the item.

2. The ultrasonic cleaning apparatus according to claim 1, wherein the ultrasonic cleaning apparatus comprises a liquid introducer arranged to in use provide a supply of fluid into the cleaning liquid in the tank so that a jet of fluid is produced.

3. The ultrasonic cleaning apparatus according to claim 2, wherein the liquid introducer comprises a jet-forming outlet at an end region thereof, wherein the jet-forming outlet is arranged to in use deliver fluid towards a region at or above the gas introducer.

4. The ultrasonic cleaning apparatus according to claim 1, wherein the ultrasonic cleaning apparatus comprises a drying gas introducer arranged to in use provide a supply of gas into the tank so that drying gas flow is produced.

5. The ultrasonic cleaning apparatus according to claim 4, wherein the drying gas introducer further comprises a tank lid comprising a fan.

6. The ultrasonic cleaning apparatus according to claim 1, wherein the gas introducer comprises a plurality of perforated pipes arranged around the inner diameter of the tank, each perforated pipe having a gas introduction conduit and a bubble forming outlet positioned at an end region of the gas introduction conduit.

7. The ultrasonic cleaning apparatus according to claim 6, wherein the gas introduction conduit is arranged to in use deliver gas across the cleaning region.

8. The ultrasonic cleaning apparatus according to claim 1, wherein the assembly is provided for actuation from within the tank.

9. The ultrasonic cleaning apparatus according to claim 1, wherein the assembly is arranged in use to be rotatable about a vertical axis.

10. A method of operating an ultrasonic cleaning apparatus, the ultrasonic cleaning apparatus comprising: a tank for receiving a cleaning liquid and for receiving an item to be cleaned in a cleaning region thereof; a transducer arranged, when driven, to direct ultrasonic pressure waves into cleaning liquid received in the tank; a controller arranged to drive the transducer; and a gas introducer comprising a plurality of spaced apart conduits arranged around an inner diameter of the tank and extending inwardly therein, the plurality of spaced apart conduits configured to supply convergent gas streams into cleaning liquid in the tank so that macroscopic bubbles of gas are produced in the tank; the method comprising: receiving cleaning liquid and the item to be cleaned in the cleaning region of the tank; driving the transducer to direct ultrasonic pressure waves into the cleaning liquid in the tank; and providing a supply of gas into cleaning liquid in the tank so that macroscopic bubbles of gas are produced from the plurality of spaced apart conduits arranged around the inner diameter in the tank, wherein the ultrasonic cleaning apparatus comprises an assembly arranged to in use enable movement of the item to be cleaned in the cleaning region, the method comprising providing movement of the item to be cleaned, wherein the apparatus comprises a liquid conduit arranged to in use deliver liquid towards the assembly to urge the assembly to move to further facilitate cleaning of the item.

11. The method of operating the ultrasonic cleaning apparatus according to claim 10, wherein the ultrasonic cleaning apparatus comprises a liquid introducer arranged to provide a supply of fluid into the cleaning liquid in the tank so that a jet of fluid is produced, and the method further comprising providing the jet of fluid from the liquid introducer.

12. The method of operating the ultrasonic cleaning apparatus according to claim 10, wherein the ultrasonic cleaning apparatus comprises a drying gas introducer arranged to provide a supply of gas into the tank so that drying gas flow is produced, and the method further comprising draining the tank and providing a supply of gas into the tank so that the drying gas flow is produced.

Description

BRIEF INTRODUCTION TO THE DRAWINGS

(1) For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which:

(2) FIG. 1 shows a schematic plan view of an ultrasonic cleaning apparatus according to an example embodiment;

(3) FIG. 2 shows a schematic side view of the ultrasonic cleaning apparatus of FIG. 1;

(4) FIG. 1A shows a schematic plan view of an ultrasonic cleaning apparatus according to another example embodiment;

(5) FIG. 2A shows a schematic side view of the ultrasonic cleaning apparatus of FIG. 1A;

(6) FIG. 3 shows a schematic plan view of an ultrasonic cleaning apparatus according to yet another example embodiment;

(7) FIG. 4 shows a schematic side view of the ultrasonic cleaning apparatus of FIG. 3;

(8) FIG. 5 shows a schematic plan view of an ultrasonic cleaning apparatus according to yet another example embodiment;

(9) FIG. 6 shows a schematic side view of the ultrasonic cleaning apparatus of FIG. 5;

(10) FIG. 7 shows a method of operating ultrasonic cleaning apparatus according to an example embodiment; and

(11) FIG. 8 shows a method of operating ultrasonic cleaning apparatus according to another example embodiment.

DESCRIPTION OF EXAMPLE EMBODIMENTS

(12) Referring now to FIGS. 1 and 2 there is shown a schematic overview of an ultrasonic cleaning apparatus 10 in accordance with an example embodiment. The ultrasonic cleaning apparatus 10 comprises a tank 12 which in use receives a cleaning liquid 14 and an item to be cleaned. The tank 12 comprises a cleaning region 16 to receive the item to be cleaned, for example a surgical instrument. The cleaning region 16 is suitably dimensioned to receive mesh racks loaded with surgical instruments for cleaning.

(13) The ultrasonic cleaning apparatus of FIGS. 1 and 2 further includes a plurality of transducers 21 arranged, when driven, to direct ultrasonic pressure waves into the tank 12. In the example embodiments of FIGS. 1 and 2 transducers 21 are illustrated on some of the side wall portions of the tank 12, but it is to be understood that this is for illustration only, and other example embodiments may be provided with a symmetrical arrangement of transducers around the cleaning region 16, such as with transducers 21 provided on each of the side walls of the tank 12. The transducers 21 are operatively coupled to a controller 30, which is supplied with power and is arranged in use to drive the transducers 21 so that they emit ultrasonic pressure waves into the tank 12.

(14) The transducers 21 are arranged in use to direct ultrasonic pressure waves into an overlapping volume in the tank 12, in the cleaning region. In this way the spread of ultrasonic pressure waves in the tank 12 can be given an effective distribution.

(15) FIG. 1 shows an example of how the transducers from the first and second pluralities of transducers 21 are coupled to frequency generators in a controller 30. Referring to FIG. 1, the plurality of transducers is arranged with the transducers grouped into first and second groups, and the controller 30 is arranged to drive transducers of the first group at a first frequency and to drive transducers of the second group at a second frequency, the second frequency being different from the first.

(16) The controller 30 uses a signal generator 31 to produce a drive signal for the transducers 21 that is characterised by a centre frequency, a sweep range about the centre frequency and a sweep rate. In the example embodiment shown, each generator is a 500 W generator. The controller 30 is arranged in use to control the signal generators 31 to switch between operation modes and output characteristics according to a cleaning cycle set in a programmable logic controller 32. In example embodiments, the sequential switching causes different combinations of primary and secondary operation for the first and second frequency generators to occur over time, for example in sequence.

(17) The controller 30 further comprises a pump controller 34 and an air pump 33. The pump controller 34, air pump 33 and conduits 40 together comprise a gas introducer that provides a supply of air into the cleaning liquid 14 in the tank 12 so that macroscopic bubbles of gas are produced. The conduits 40 are arranged to provide a plurality of bubble sources distributed below the cleaning region 16 of the tank 12. In other embodiments a compressed air container may be used in place of the pump and controller, with appropriate modifications to selectively release and interrupt the supply of gas as required. Although the bubble produced are described as macroscopic, in order to distinguish from the microscopic cavitations provided by the application of ultrasound, the size of the bubble may be controlled to enable better contact with the cleaning liquid, for example by the use of thimble-like porous diffusers (not shown) provided at the end of some or all of the conduits.

(18) FIGS. 1A and 2A show another example embodiment. In FIGS. 1A and 2A reference numerals preceded by an additional number 1 are used to illustrate corresponding integers to those integers shown in FIGS. 1 and 2. In the embodiment of FIGS. 1A and 2A the tank 112 is in the form of a trough, and the items to be cleaned are print rollers R. The conduits 140 comprises perforated pipes, which when supplied with air from the air pump 133 produce macroscopic bubbles distributed along their length.

(19) FIGS. 3 and 4 show another example embodiment. In FIGS. 3 and 4 reference numerals are used to illustrate corresponding integers to those integers shown in FIGS. 1 and 2. It will be appreciated that the various changes and modifications, illustrated and described, of FIGS. 3 and 4 when compared with FIGS. 1 and 2, may also be made to the example embodiment of FIGS. 1 and 2, without departing from the scope of the invention, as disclosed in this document.

(20) The ultrasonic cleaning apparatus 10 further comprises an assembly 80, arranged in the cleaning region 16, to receive surgical instruments for cleaning. In the example embodiment shown the assembly 80 comprises a mesh rack 88 suitably dimensioned to receive surgical instruments for cleaning, and in other example embodiments may comprise a stack of racks 88, each rack suitably dimensioned to receive surgical instruments for cleaning. The assembly 80 comprises a rotor 81 that includes a plurality of blades 82 arranged about a drum 84. The assembly 80 still further comprises a shaft 86 arranged on, and projecting upwardly from the bottom wall of the tank 12. The shaft 86 may be mechanically fixed, welded, adhered or magnetically attached or otherwise secured to the bottom wall of the tank 12. The drum 84 is arranged to rotate about a vertical axis defined by the shaft 86. The shaft 86 may present a generally horizontal bearing surface, or mounting surface for a bearing at an upper end thereof, and may also provide a central feature, for example a pin or recess to centre the rotor 81 thereon and to enable, the rotor to turn freely thereon. The contact between the shaft 86 and the rotor 81 may be provided by a rolling contact bearing at their interface for example, in such a way that the rotor 81 rests on the bearing to move. In example embodiments a bearing between the shaft 86 and rotor 81 is provided in an arrangement so that the rotor 81, and optionally also the bearing to may be readily removed from the shaft 86, and from the tank 12 for example to enable periodic maintenance or replacement, or in the case of the assembly 80 to enable items to be loaded onto the rack 88 or removed therefrom outside of the tank 12.

(21) A conduit 40 is arranged to further in use deliver bubbles towards one or more of the blades 82. These bubbles in use impinge on the blades 82 and tend to rotate the assembly 80 about the axis of the shaft 86. A plurality of conduits 40 may be arranged to each in use deliver bubbles towards one or more blades 82. The induced rotation of the assembly 80 may be continuous or intermittent and may be controllable by the controller 30 supplying signals to start and stop the supply of bubbles through the conduits 40. In this embodiment the conduit 40 comprises part of the gas introducer described above.

(22) The assembly 80 is intended to minimise locations in the tank that, retain, entrain or otherwise retain dirt that may reduce the effectiveness of the clean from one cleaning operation in the tank to the next. Further, the arrangement of the assembly 80 in the cleaning region 16 means that the assembly 80 is itself in use cleaned. For example, in cleaning surgical instruments before sterilisation, there may be various types of biological material on the instruments, in different sized clumps, that are removed by cleaning from the surface which is being cleaned but this biological material may be transferred to and retained in the tank by a rack, mount, support or holder for the surgical instruments. The arrangement of the assembly 80 minimizes the transfer and retention of the biological material and thus dirt is effectively removed from surfaces in the tank so as to guarantee that the cleaning process can be performed effectively.

(23) In the embodiments of FIGS. 3 and 4, blades 82 are illustrated on the underside of the assembly 80, but it is to be understood that this is by way of example only, and other example embodiments may be provided, such as with a blade provided on a side of the assembly 80 or above the assembly 80 or on one or more of the underside, a side and above the assembly 80. In the example embodiments of FIGS. 3 and 4, the gas introducer is arranged such that bubbles delivered therefrom exit in a generally horizontal initial direction, to send bubbles in a lateral direction, sideways towards the blades 82, but it is to be understood that this is for illustration only. In other example embodiments the gas introducer may be provided, such as with a gas introducer provided in the tank 12 and arranged to in use deliver bubbles below one or more blades 82 that are angled with reference to rising of bubbles in the tank, in order to thereby urge the assembly 80 to rotate by reaction force as the bubbles rise.

(24) By providing movement as described a more effective clean can be obtained, since the items to be cleaned pass through different areas in the tank and thereby do not remain in any one spot in the cleaning region where relatively weak ultrasonic activity is provided. As set out above, ultrasonic cleaning apparatus according to example embodiments are arranged to provide movement of the items to be cleaned in use, thereby increasing effectiveness of the clean across the whole surface of the item to be cleaned. Providing movement of the items to be cleaned in use also reduces surface erosion or other damage across the whole surface of the item to be cleaned.

(25) FIGS. 5 and 6 show yet another example embodiment. In FIGS. 5 and 6 reference numerals are used to illustrate corresponding integers to those integers shown in FIGS. 1 and 2. It will be appreciated that the various changes and modifications, illustrated and described, of FIGS. 5 and 6 when compared with FIGS. 1 and 2, may also be made to the example embodiment of FIGS. 3 and 4, without departing from the present disclosure. It will be appreciated that the various changes and modifications, illustrated and described, of FIGS. 3 and 4 when compared with FIGS. 1A and 2A, may also be made to the example embodiment of FIGS. 1A and 2A, without departing from the scope of the invention, as disclosed in this document.

(26) The controller 30 further comprises a liquid pump controller 35 and a liquid pump 36. The liquid pump controller 35, liquid pump 36 and conduits 50 together comprise a liquid introducer that provides a supply of liquid into the cleaning liquid 14 in the tank 12 so that jets of liquid are produced. The liquid conduits 50 are arranged to provide a plurality of liquid jet sources arranged at a plurality of depths to in use deliver liquid towards the cleaning region 16 of the tank 12 and towards the macroscopic bubbles of gas. The outlet of drain 60 is connectable to the liquid introducer such that the cleaning liquid 14 is circulated by the liquid introducer.

(27) In yet another example embodiment (not shown), the example embodiment of FIGS. 5 and 6 comprises a liquid introducer in which the liquid introducer serves as a fluid introducer to supply both cleaning fluid and gas. The controller further comprises a fluid pump, controller and a fluid pump. The fluid pump controller, fluid pump and conduits together comprise a fluid introducer that provides a supply of fluid into the cleaning liquid 14 in the tank 12 so that jets of fluid are produced which are a mixture of cleaning liquid and bubbles of gas. The gas in this example embodiment comprises air. The fluid conduits are arranged to provide a plurality of fluid jet sources arranged at a plurality of depths to in use deliver fluid towards the cleaning region 16 of the tank 12 and towards the macroscopic bubbles of gas as they rise through the cleaning region and to further agitate the cleaning fluid in the cleaning region. The outlet of drain 60 is connectable to the fluid introducer such that the cleaning liquid 14 is circulated by the fluid introducer.

(28) As set out above, ultrasonic cleaners according to example embodiments can provide physical agitation of the cleaning liquid to aid dirt removal, and the introduction of gas bubbles increases the amount of gas dissolved in the cleaning liquid, thereby increasing the effect of the ultrasonic cavitation. Use of one gas introducer to cause the movement/agitation and increase the amount of dissolved gas offers a way to improve cleaning without unnecessary complication. Providing the bubbles below the cleaning region, their effect is maximised in the region of interest as they rise up and pass over and around items to be cleaned. Providing the liquid jets further increases the physical agitation of the cleaning liquid to aid dirt removal. Providing the liquid jets to disrupt the bubbles further increases the effect of ultrasonic cavitation. By use of suitable cleaning liquids it is possible to give a good cleaning effect on items contaminated with different types of biological dirt and also on delicate items, for example items of medical or surgical equipment or print rollers, without causing significant surface erosion or other damage.

(29) It will be appreciated that the various changes and modifications, illustrated and described, of FIGS. 3 and 4 when compared with FIGS. 5 and 6, may also be made to the example embodiment of FIGS. 5 and 6, without departing from the present disclosure. In particular, a liquid conduit 50 may be arranged to further in use deliver liquid towards or below one or more blades 82, which are arranged in use to thereby rotate the assembly 80 about the vertical axis of the shaft 86.

(30) The ultrasonic cleaning apparatus 10 further comprises a removeable tank lid 70, that comprises a fan controller 71, a fan 72, drying gas inlet 73 and drying gas outlets 74. The fan controller 71, a fan 72, drying gas inlet 73 and drying gas outlets 74 together comprise a drying gas introducer that provides a supply of drying air into the tank 12 as a means of drying. The conduits 74 are arranged to provide a plurality of drying gas sources distributed below the cleaning region 16 of the tank 12.

(31) FIG. 7 shows a method of operating ultrasonic cleaning apparatus according to an example embodiment. At S11, cleaning liquid is received in the tank and an item to be cleaned is received in the cleaning region of the tank. At S12, the transducers are driven to direct ultrasonic pressure waves into the cleaning liquid received in the tank. At S13, a supply of gas is provided into the cleaning liquid received in the tank so that macroscopic bubbles are produced such that a plurality of bubble sources are distributed below the cleaning region of the tank. At S14, a supply of fluid is provided into the cleaning liquid received in the tank so that a jet of fluid is produced to agitate the cleaning liquid and the bubbles produced in the cleaning liquid received in the tank, although in certain example embodiments this step may be optionally omitted. The fluid comprises a mixture of cleaning liquid and air. At S15, the tank is drained of cleaning liquid. At S16, a supply of gas is provided in the tank to produce a drying gas flow, although again this step being optionally omitted in certain example embodiments, independently of the optional performance of step S14. It will be understood that in the cleaning process the order of steps relating to driving of the transducers, supply of gas for bubble formation and the provision of jets of cleaning liquid can be varied, for example to commence simultaneously, or in other sequential order as appropriate.

(32) FIG. 8 shows a method of operating ultrasonic cleaning apparatus according to another example embodiment. In FIG. 8, like reference numerals are used to illustrate corresponding steps to those steps shown in FIG. 7. At S11, cleaning liquid is received in the tank and an item to be cleaned is received in an assembly in the cleaning region of the tank. At S12, the transducers are driven to direct ultrasonic pressure waves into the cleaning liquid received in the tank. At S13, a supply of gas is provided into the cleaning liquid received in the tank so that macroscopic bubbles are produced such that a plurality of bubble sources are distributed below the cleaning region of the tank and such that the assembly tends to move. At S14, a supply of fluid is provided into the cleaning liquid received in the tank so that a jet of fluid is produced to agitate the cleaning liquid and the bubbles produced in the cleaning liquid received in the tank and so that the assembly tends to move, although in certain example embodiments this step may be optionally omitted. The fluid comprises a mixture of cleaning liquid and air. At S17, movement of the item to be cleaned is provided by the movement of the assembly. At S15, the tank is drained of cleaning liquid. At S16, a supply of gas is provided in the tank to produce a drying gas flow, although again this step being optionally omitted in certain example embodiments, independently of the optional performance of step S14. It will be understood that in the cleaning process the order of steps relating to driving of the transducers, supply of gas for bubble formation and the provision of jets of cleaning liquid can be varied, for example to commence simultaneously, or in other sequential order as appropriate.

(33) As set out above, ultrasonic cleaners according to example embodiments can provide in situ drying, thereby reducing the risk of contamination and/or damage after cleaning.

(34) Although a few preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, and as may also be defined in any appended claims.

(35) Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

(36) All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

(37) Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

(38) The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.