AU2003204168B2 - An electrolytic chlorinator device - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: WATERMAID PTY LIMITED Andrew Edward Romer Address for Service: Invention Title: Details of Basic Application(s): HODGKINSON OLD McINNES Patent Trade Mark Attorneys Levels 3 and 4, 20 Alfred Street MILSONS POINT NSW 2061 AN ELECTROLYTIC CHLORINATOR

DEVICE

Australian Provisional Patent Application No. PS2715 filed 31 May 2002 The following statement is a full description of this invention, including the best method of performing it known to us: 2972G 00 c,1 FIELD OF THE INVENTION The present invention relates to electrolytic chlorinators such as those used in swimming ;pools, air conditioning units, and the like and, in particular, to the cleaning of the electrodes of same.

00 BACKGROUND ART Swimming pool chlorinators had been in use for many years and consist essentially of an anode and a cathode and a power supply to supply an electric potential between the anode and cathode with the anode being positive with respect to the cathode. The anode is typically made of any metal, usual titanium which is then provided with an exterior layer of platinum which is plated or baked onto the titanium or other metal. In addition to platinum, indium, ruthenium, etc can be used. The cathode is normally fabricated from pure titanium of grade 2 quality or better (that is it has essentially no iron and low oxygen in the titanium).

The anode attracts negative ions in the swimming pool water including chloride ions.

Thus the water in the immediate vicinity of the anode is very acidic. For this reason the anode is coated with platinum which is a very expensive material. The cathode attracts positive ions including calcium, silicates and magnesium carbonates. These build up on the cathode and form a deposit which progressively reduces the efficiency of the electrolytic cell formed by the anode and cathode. One way of cleaning the cathode is to wash the cell with diluted acid which dissolves the deposits on the cathode.

It is also known to clean the cathode by reversing the polarity of the voltage applied between the cathode and anode. This has the effect that calcium deposits etc on the cathode try to go back into solution and are thereby dissipated. However, with the conventional titanium cathode and platinum anode arrangement (which costs approximately A$350) it is known that only 30-100 reversals of polarity are sufficient to destroy the working life of the expensive platinum anode. This is as a result of the platinum breaking away from the underlying metal at the metal/platinum interface.

2972G 00 SIt is also known to provide a more expensive type of reversible polarity electrodes which cost approximately A$600 but which permit from 2000-3000 reversals to be carried out before the electrodes suffer damage. This equates to a usable life of approximately two years.

0Thus at present a consumer has a choice between a relatively inexpensive electrode which will last in excess of 10 years and the burden of repeated cleaning of same, or a relatively expensive electrode which will only last approximately 2 years but does not have the burden of needing to be repeatedly cleaned.

GENESIS OF THE INVENTION The genesis of the present invention is a desire to provide an arrangement whereby inexpensive electrodes may be automatically cleaned by reversed polarity without substantially reducing the operating life.

SUMMARY OF THE INVENTION According to a first aspect of the present invention there is disclosed a dual mode electrolytic chlorinator device to maintain clean electrodes, said device comprising an anode, a cathode and at least one auxiliary electrode having a primary function unrelated to electrode cleaning, a base load power supply connected to said anode and cathode to supply a potential difference thereto with said anode being positive with respect to said cathode, a cleaning cycle power supply connected to said cathode and said auxiliary electrode to supply a potential difference thereto with said cathode being positive with respect to said auxiliary electrode, a time activated switching means connected to said cleaning cycle power supply to activate same for a small fraction of the time that said base load power supply is activated and wherein said cleaning cycle power supply includes a polarity reversing switch means operable to reverse the polarity of the potential difference supplied to said cathode and auxiliary electrode to thereby maintain said auxiliary electrode substantially clean.

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N According to a second aspect of the present invention there is disclosed a method of operating a dual mode electrolytic pool chlorinator device to maintain clean electodes, said device comprising an anode, a cathode, an auxiliary electrode having a primary function unrelated to electrode cleaning and a source of electric potential, said method comprising the steps of:- Si) applying a potential to said anode and cathode during a base load period during which said anode is positive with respect to said cathode, ii) applying a potential to said cathode and said auxiliary electrode during a cleaning cycle period which is a small fraction of said base load period during which said cathode is positive with respect to said auxiliary electrode, and iii) reversing the polarity of said cathode with respect to said auxiliary electrode to maintain said auxiliary electrode substantially clean.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will now be described with reference to the drawings in which: Fig. 1 is a schematic perspective view of the electrodes of a swimming pool chlorinator device, Fig. 2 is a circuit diagram showing the switching of the electrode polarities utilising relay technology, Fig. 3 is a timing diagram applicable to the operation of the circuit of Fig. 2, and Fig. 4 is a FET realisation of the circuit of Fig. 2.

DETAILED DESCRIPTION As seen in Fig. 1, the inexpensive electrode system used in an electrolytic chlorinator such as a swimming pool chlorinator device 1 consists of a central cylindrical cathode 2 which is surrounded by a cylindrical anode 3. A gas sensing electrode 4, typically fabricated from a small piece of titanium metal is provided adjacent the cathode 2 and anode 3 and at the top of the pipe or other body (not illustrated) which contains the cathode 2 and anode 3 and the swimming pool water. The cathode 2, anode 3 and gas sensing electrode 4 are supplied by a power supply 2972G 00 In known fashion a small current is run between the gas sensing electrode 4 and either one, or both, of the cathode 2 and anode 3. This current indicates that there is liquid adjacent the cathode 2 and anode 3 and thus the pump of the swimming pool is functioning correctly. If the pump were to stop, for example, then gas would build up 00 around the gas sensing electrode 4 and interrupt the small current. The power supply 5 is

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arranged to be switched off if the small current from the gas sensing electrode 4 stops Sflowing, thereby indicating the possibility of a dangerous buildup of gas.

S 10 Turning now to Fig. 2, in accordance with a first embodiment of the present invention, the power supply 5 is modified so as to enable a reverse polarity cleaning cycle to take place utilising the cathode 2 and the gas sensing electrode 4. As seen in Fig. 2 a first switch S 1 is provided with four contacts of which two are normally closed contacts S IA and SID and two are normally open contacts S1B and S1C. All four contacts are operable together. A second switch S2 is provided having two contacts each of which is single pole double throw.

Fig. 3 illustrates the timing of the operation the switches S 1 and S2. The duty cycle is that the base operation of the electrolytic cell operates for, say, one hour and at the last, say, five minutes of that hour the switch S 1 is operated. For the last, say, 5-30 seconds of that five minutes the switch S2 is operated.

The operation of switch S 1 disconnects the gas sensing electrode 4 from the regular power supply 5 and instead connects the electrode 4 via contacts S2B and S 1C to a negative polarity represented by the negative terminal of a battery in Fig. 2.

Simultaneously, the cathode 2 is connected via contacts S2A and SIB to a positive polarity represented by the positive terminal of the battery in Fig. 2. Thus, a reverse polarity current flows between electrode 4 and cathode 2 which cleans the cathode 2.

At the same time, reverse polarity current is depositing material on the negative terminal which is the gas sensing electrode 4. Therefore, if the above described cleaning process 2972G 00 N were to continue indefinitely, the gas sensing electrode 4 would become increasingly inoperative and thereby shut down the power supply 5. In order to prevent this build up on the electrode 4, the switch S2 is operated just at the end of the cleaning cycle and functions to reverse the polarities applied to cathode 2 and electrode 4. That is, reverse polarity cleaning is applied for, say, 5-30 seconds to the electrode 4. This has proved 0sufficient to maintain the electrode 4 in a satisfactorily clean state.

Fig. 4 illustrates a solid state embodiment utilising four FET devices which together with two NAND gates create the logic required to carry out the function of switches S 1 and S2.

The foregoing describes only some embodiments of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope of the present invention. For example, although in Fig. 2 the anode 3 is disconnected during the cleaning cycle by contact S 1D, it is not necessary that the anode 3 be so disconnected.

Furthermore, although the preferred voltage applied between the electrode 4 and cathode 2 is approximately 10 volts resulting in a current of typically 100 mA, a different magnitude of voltage and current can be used, if desired.

In addition, although the gas sensing electrode 4 is present in the conventional low cost electrode structure, it is possible to use an alternative electrode as the auxiliary electrode which becomes the negative electrode during the cleaning of the cathode 2. Naturally, utilising the existing gas sensing electrode 4 represents a convenient solution. Such an auxiliary electrode can be provided with a larger surface area than the gas sensing electrode 4 in which case the time of reverse polarity cleaning is able to be reduced.

Although the above arrangement describes cylindrical electrodes which can be fabricated from sheet or mesh material, the electrodes can also be of other shapes such as flat sheets, discs, etc. Furthermore, the time of operation of the cleaning cycle and the polarity 2972G 00 r reversal within the cleaning cycle can vary depending upon the nature of the deposited scale or the content of the water. Similarly, the magnitude of the voltage and current used in the cleaning action can be varied if desired. In general, a larger current results in a quicker cleaning action. Similarly, larger electrode surface areas result in more even distribution of cleaning.

00 The term "comprising" (and grammatical variations thereof) as used herein is used in the Sinclusive sense of "having" or "including" and not in the exclusive sense of "consisting only of'.

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Claims (9)

1. A dual mode electrolytic chlorinator device to maintain clean electrodes, said device comprising an anode, a cathode and at least one auxiliary electrode having a primary function unrelated to electrode cleaning, a base load power supply connected to said anode and cathode to supply a potential difference thereto with said anode being 0positive with respect to said cathode, a cleaning cycle power supply connected to said cathode and said auxiliary electrode to supply a potential difference thereto with said cathode being positive with respect to said auxiliary electrode, a time activated switching means connected to said cleaning cycle power supply to activate same for a small fraction of the time that said base load power supply is activated and wherein said cleaning cycle power supply includes a polarity reversing switch means operable to reverse the polarity of the potential difference supplied to said cathode and auxiliary electrode to thereby maintain said auxiliary electrode substantially clean.

2. The device as defined in claim 1 wherein said time activated switching means is connected to said polarity reversing switch means to operate same for a small fraction of the time said cleaning cycle power supply is activated.

3. The device as defined in claim 1 or 2 wherein said auxiliary electrode comprises a gas sensing electrode.

4. The device as defined in any one of claims 1 to 3 wherein said time activated switching means is connected to said anode and disconnects said anode during activation of said cleaning cycle power supply.

An electrolytic chlorinator device substantially as herein described with reference to the drawings.

6. A method of operating a dual mode electrolytic pool chlorinator device to maintain clean electodes, said device comprising an anode, a cathode, an auxiliary electrode having a primary function unrelated to electrode cleaning and a source of electric potential, said method comprising the steps of:- i) applying a potential to said anode and cathode during a base load period during which said anode is positive with respect to said cathode, 2972G 00 ii) applying a potential to said cathode and said auxiliary electrode during a 3~ cleaning cycle period which is a small fraction of said base load period during which said cathode is positive with respect to said auxiliary electrode, and iii) reversing the polarity of said cathode with respect to said auxiliary electrode to maintain said auxiliary electrode substantially clean. 00

7. The method as defined in claim 6 including the step of: iv) using said auxiliary electrode as a gas sensing electrode.

8. The method as described in claim 6 or 7 including the further step of:- v) disconnecting said anode during the cleaning cycle period. S 10

9. A method of operating an electrolytic chlorinator device, said method being substantially as herein described with reference to the drawings. Dated this 22nd day of July 2008 WATERMAID PTY LIMITED BY: FRASER OLD SOHN Patent Attorneys for the Applicant 2972G