AU684550B2 - An electrolysis apparatus, and a power supply and cell therefor - Google Patents

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT (Original) APPLICATION NO:

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RELATED ART: too..: 0 0 *o *a NAME OF APPLICANT: ACTUAL INVENTOR(S): ADDRESS FOR SERVICE; INVENTION TITLE: NEWBAH PTY LTD TERENCE MICHAEL HUNTER KELVIN LORD AND COMPANY, Patent Trade Mark Attorneys, of 4 Douro Place, West Perth, Western Australia, 6005, AUSTRALIA.

"AN ELECTROLYSIS APPARATUS, AND A POWER SUPPLY AND CELL THEREFOR" DETAILS OF ASSOCIATED PROVISIONAL APPLICATION NO'S: PM 2081 filed 29.10.93 The following Statement is a full description of this invention including the best method of performing it known to me/us: a u The present invention relates to an electrolysis apparatus. In particular, the present invention relates to an electrolysis apparatus for the chlorination of salt water swimming pools.

Traditionally, chlorinators for salt water swimming pools have consisted of a power supply providing a constant electrical potential between a pair of electrodes comprising a cell immersed in the salt water to be chlorinated. However, if the salt content of the water is high, large currents can be drawn by the cell, wearing the electrodes faster and possibly damaging them. Additionally, large currents may overload the power supply, causing failure of the chlorinator.

Further, deposits are known to accumulate on the cathodic electrode, reducing the efficiency of the cell. Such deposits require periodic cleaning of the cell electrodes in an S: acidic solution, an onerous and undesirable task.

oeeoe o If the deposits are not cleaned from the cathodic electrode, the deposits can accumulate until they contact the anodic electrode. When this occurs, the resulting overload can 15 damage both the cell and the power supply.

Prior art chlorinators have approached the problem of accumulation of deposits by periodically reversing the polarity of the constant electrical potential applied to the cell.

However, the reversal of polarity of the constant electrical potential produces very high surge currents at the instant of reversal Thus, prior art chlorinators have had to employ 20 such methods as decreasing the electrical potential in a series of steps, then reversing the polarity and then increasing the electrical potential in a second series of steps. This has the disadvantage of lowering the efficiency of the cell and does not entirely eliminate surge currents.

There is additionally an inherent problem with controlled electrical potential chlorinators in that the rate of production of chlorine is very dependent upon the amount of salt in the water. Thus, the efficiency of the cell is variable, making it difficult to determine how long the chlorinator needs to be in operation to maintain the desired level of chlorine. Further, ii the salinity is too low, wear on the cell increases, whilst if the salinity is too high, the chlorinator may be overloaded.

According to a first aspect of the present invention there is provided a power supply for a salt water chlorinator comprising a current control means, a timer means and a polarity reversal means, wherein the current control means produces a controlled electrical current, the controlled electrical current having a polarity which is periodically reversed by the polarity reversal means at a time interval determined by the timer means.

According to a second aspect of the present invention there is provided a salt water chlorinator comprising a power supply according to the first aspect of the present invention and a cell for a salt water chlorinator comprising a first and a second electrode capable of connection to a power supply and at least one additional electrode arranged between the first and second electrodes, the power supply being connected to the cell to deliver a controlled electrical current to the cell.

Preferably, the number of additional electrodes is preferably between 1 and 11 inclusive.

.The present invention will now be described, by way of exanmple, with reference to the 15 accompanying drawings, in which: Figure 1 is a block diagram of a power supply in accordance with the present invention; Figure 2 shows examples of waveforms generated by the power supply of Figure 1; Figure 3 shows a cross-sectional view ofa cell in accordance with the present invention, and 20 Figure 4 shows a perspective view, partially broken away, of the cell shown in Figure 3.

Shown in Figure 1 of the accompanying drawings is a power supply 10 comprising a transformer 12, a controller 14 and a rectifier means 16. The transformer 12 is of known type and produces an output AC voltage. The output AC voltage of the transformer 12 is connected to the controller 14 and the rectifier means 16.

The power supply 10 is typically for use in a salt water chlorinator comprising a pump, a cell and a filter.

Connected to the controller 14 is a meter 18, an indicator 20 and a gas detector 22, The controller 14 connects to the rectifier means 16 through the gas detector 22. A current sensor 23 is connected to the rectifier means 16. The current sensor 23 is also connected to a load 26, a fault detector 24 and the controller 14. The load 26 is connected to the fault detector 24. The fault detector 24 is connected to the indicator The pump (not shown) of the salt water chlorinator is connected to the power supply such that whenever power is applied to the transformer 12 the pump is activated.

The controller 14 comprises in part a delay timer which delays activation of the rectifier means 16 for a specified time, for example 20 30 seconds. When the power supply is used in the salt water chlorinator, the delay from the delay timer allows the pump, the cell and the filter to prime prior to the application of power to the cell.

Additionally, the controller 14 further comprises a timing means and a current control means. The current control means produces an output which is used to control the operation of the rectifier means 16. The output of the current control means is also used .:o.oi to provide a signal to the meter 18.

The meter 18 is of known type and forms a display based on the signal received from the 15 controller 14. From the display of the meter 18, a user is able to ascertain the quantity of current being produced by the power supply The controller 14 also provides a signal to enable or disable the indicator A signal is received by the controller 14 from the current sensor 23. The signal is representative of the current produced by the rectifier means 16.

The current control means of the controller 14 uses a predetermined value corresponding to a desired current level and the signal from the current sensor 23 in a feedback loop to determine whether to modify the signal sent to the rectifier means 16 so as to increase or decrease the current produced by the rectifier means 16, If the gas detector 22 indicates that there is a gas build up in the load 26, the gas detector 22 will disable the rectifier means 16, by preventing the signal from the controller 14 reaching the rectifier means 16.

The timing mea.ns of the controller 14 determines the time interval between polarity reversal of the current produced by the rectifier means 16. When the timer means indicates that a polarity reversal is called for, the current control means alters the signal sent to the rectifier means 16, whereby the rectifier means 16 reverses the polarity of the current produced. Since the current produced by the rectifier means 16 is controlled, surge currents are eliminated which may otherwise damage the load 26 or the power supply as further described hereinafter.

The rectifier means 16 comprises, for each secondary winding of the transformer 12, a triac and a trigger means. Each trigger means typically comprises an optocoupler. The or each optocoupler receives the signal produced by the current control means anid activates or deactivates the or each triac accordingly. By altering at which point in a cycle of the output AC voltage produced by the transformer 12 the or each optocoupler activates the or each triac, the current control means can vary the current produced by the rectifier means 16. Thus, the controller 14 and the rectifier means 16 produce a phase controlled current.

Reversal of the polarity of the current produced by the rectifier means 16 is achieved by 15 the current control means altering the signal such that the or each optocoupler act;vates the or each triac in a part of the cycle of the output AC voltage produced by the L tnsformer 12 which is of opposite polarity to that presently used, The current sensor 23 monitors the current produced by the rectifier means 16 which is applied to the load 26. The signal generated by the current sensor 23 is proportional to 20 the magnitude of the cu.=nt produced by the rectifier means 16 and is output to both the controller 14 and the fault detector 24.

0".i The fault detector 24 receives signals from the current sensor 23 and the load 26 and determines from them any fault condition. Thus, when gas build up is detected in the load 26, or if the salinity of the water is too low or too high, the fault detector 24 will produce a signal to be sent to the indicator 20, The salinity of the water can be inferred from the amount of current produced by the rectifier means 16, corresponding to the signal produced by the current sensor 23.

The indicator 20 receives signals from the controller 14 and the fault detector 24 and I produces a display such that the user can determine the existence of any faults. The indicator 20 can be of any convenient type, for example LED's.

The load 26 is typically an electrolytic cell immersed in a salt water solution, for example the cell of the salt water chlorinator.

In use, power is supplied to the transformer 12 which provides power to the controller 14 and the rectifier means 16. After a timed delay, typically of between 20 and 30 seconds, the controller 14 activates the rectifier means 16 which thereby produces a current.

The current is delivered to the loa 26 via the current sensor 23. The current sensor 23 provides a signal to the controller 14, I: allowing the controller 14 to regulate the current produced by the rectifier means 16 and keep the current produced at the desired level, The desired level of current is selectable by the user via a control means, such as a potentiometer.

The meter 18 and indicator 20 provide displays to allow the user to ascertain the status of the power supply 10 as previously described.

15 When polarity reversal occurs, the change has effect immediately; there are no intermediate steps or gradual reductions. Thus, there is only a minimal loss of power to the load 26. Since the current from the power supply 1U is controlled, surge currents such as would otherwise be present under polarity reversal in a chlorinator are eliminated.

Thus, the power supply 10 acts to prevent damage both to itself and the load 26.

20 As shown in Figure 2 are waveforms A-I which may be generated by the power supply The horizontal axis of each waveform is time, with dashed vertical lines indicating a single momen in time. The waveform shown in Figure 2 corresponds to a power supply of the present invention adapted for use with a transformer having a centre tap secondary winding. Further, two opto couplers (opto coupler 1 and opto coupler 2) and two triacs (triac 1 and triac 2) are used in the power supply.

Waveforms A and B show the AC output of the secondary winding of the transformer.

The dashed vertical lines separate the time axis into half cycles of the AC output of the transformer, labelled 1 to 8. Waveform A is of opposite polarity to waveform B due to the centre tapping of the transformer. Waveform A is input to triac 1 and waveform B is input to triac 2.

Waveforms C and L, ,w the control signals generated by the controller 14 and input to the opto couplers. Waveform C is input to opto coupler 1 and waveform D is input to opto coupler 2.

Waveforms E and F show the gate current of the triacs. Waveform E shows the gate currents of triac 1 and waveform F shows the gate current of triac 2. It should be noted that the current flowing into the gate of the triacs, triac 1 and triac 2, is always positive, and therefore, the waveforms E and F shown in Figure 2 are merely representative, and are not referenced to grout d.

Waveforms G and H represent the output oftriac 1 and triac 2 respectively.

Waveforms I represents the .:ell current, being the sum of waveforms G and H.

As can be seen from Figure 2, the opto couplers are each connected to both triacs.

Therefore, opto coupler 1 is capable of triggering triac 1 or triac 2, and opto coupler 2 15 is equally capable of triggering triac 1 or triac 2. Whether triac 1 or triac 2 is triggered depends upon the phase of the transformer output input to the triac. Opto coupler 1 is connected to triac 1 and triac 2 such that triac 1 or triac 2 will only trigger if the current Sinput from the transformer to the triac has a positive polarity. Further, opto coupler 2 is connected to triac 1 and triac 2 such that the triac 1 and triac 2 will only trigger if the 20 input from the transformer to the triac has a negative polarity.

Consequently, as can be seen in Figure 2, waveform C can be used to control opto coupler 88 1 to provide a phase controlled cell current having a positive polarity, and waveform D can be used to control opto coupler 2 to produce a phase controlled cell current having a negative polarity.

Further, the cell current can be controlled by varying the width of the control pulse sent to the opto couplers. As can be seen in waveforms C and D by reducing the width of the control signal, the quantity of current produced can be varied. It should be noted that to achieve effective control, a shortened control pulse should always occur at the end of a I- 1 half cycle, as shown in waveforms C and D, This is because once a triac has triggered, it remains active until the input from the transformer changes polarity.

Further, it should be noted that rne of the control signals shown in waveforms C and D cross any of the vertical lines delineating the half cycle time intervals. This is because a control signal present when the waveforms A and B change polarity may incorrectly trigger a triac, and may also incorrectly trigger triac 1 and triac 2 into opposite polarities, thereby damaging the triacs. Therefore, the control signals shown in waveforms C and D always end shortly before and always commence shortly after each vertical line, or the beginning of each half cycle.

Shown in Figures 3 and 4 of the drawings is an electrolytic cell 40 comprising a casing 42, a first electrode 44, a seond electrode 46 and additional electrodes 48. Attached to each of the electrodes 44 and 46 is a connector 50. The connectors 50 are designed to be connected to a power supply, typically creating an electrical potential difference between the electrodes 44 and 46. The electrodes 44 and 46 are held in place in the casing 42 by 15 a pair of grooves 52 formed in the casing 42. The electrodes 44 and 46 are arranged substantially parallel and located adjacent opposed sides of the casing 42.

too*. Disposed between the electrodes 44 and 46 are the additional electrodes 48. Each additional electrode 48 has a first side 54 and a second side 56. The side 54 faces the a, electrode 46 and the side 56 faces the electrode 44. Preferably the additional electrodes 48 are spaced equally between the electrodes 44 and 46 and arranged substantially parallel therewith. Each additional electrode 48 is held in place by a groove 58 in the casing 42, :The additional electrodes 48 provide an increased surface area for the electrolysis process a9 to occur. For the same electrical current, an increased amount of chlorine is electrolysed in salt water. The cell 40 can therefore be used to increase the efficiency of a chlorinator for a salt water pool without consuming additional power, The electrodes 44, 46 and 48 are preferably in the form of a plate.

However, other arrangements are possible. For example, the electrodes 44,46 and 48 may be in the form of concentric cylinders through which water flows. The outer cylinder and II-- the innermost cylinder would be the electrodes 44 and 46, with the additional electrodes 48 disposed therebetween.

In use, the cell 40 would be installed in known manner as part of the pumping mechanism in a salt water pool. Water flows through the casing 42 past the electrodes 44, 46 and 48.

As water flows past the electrodes 44, 46 and 48, power supplied to the electrodes 44 and 46 via connectors 50 result in a flow of ions between the electrodes 44, 46 and 48.

However, ions only need to flow to the nearest electrode of the correct polarity. The sides 54 of the electrodes 48 have the same polarity as the electrode 44. The sides 56 of the additional electrodes 48 have the same polarity as the electrode 46.

In the cell 40 shown in Figures 3 and 4, there are effectively five pairs of anodes and cathodes. Tiierefore, the cell 40 shown in Figures 3 and 4 produces up to five times as o* a much chlorine as a cell which omitted the additional electrodes 48.

If the cell 40 is connected as the load 26 of the power supply 10, a chlorinator according to the present invention is produced. The chlorinator combines the advantages of both the se'"e 15 cell 40 and the power supply The power supply 10 of the present invention allows controlled regulation of the rate of chlorine production by varying the current produced. In addition, polarity reversal of the

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current from the power supply 10 provides a mechanism for self cleaning of the cell obviating the need for cleaning the electrodes of the cell 40 in acid to remove deposits thereon.

Modifications and variations such as would be apparent to a skilled addressee are deemed S* within the scope of the present invention,

Claims (10)

1. A power supply for supplying current to a cell of a salt water chlorinator, comprising a timer means, a polarity reversal means and a current control means, the current control means producing an electrical current which is controlled so as to remain substantially constant in average magnitude and the said controlled electrical current having a polarity which is periodically reversed by the polarity reversal means at a time interval determined by the timer means.

2. A power supply according to claim 1, wherein the power supply further comprises a delay means, which delay means prevents production of the controlled electrical current for a predetermined time interval after activation of the power supply.

3. A power supply according to wither one of claims 1 or 2, wherein the controlled electrical current is a phase controlled direct current electrical current.

4. A power supply according to any one of the preceding claims, wherein control of the electrical current is achieved by adjusting a duty cycle which determines which portion of a cycle of an alternating current electrical potential input to the current control means is used to produce the electrical current, A power supply according to claim 4, wherein a feedback loop controls adjustment of the duty cycle.

6. A power supply according to either of claims 4 or 5, wherein the duty cycle is 2V' arranged such that the portion of the cycle of the alternating current electrical potential is of constant polarity. S 7. A power supply according to claim 6, wherein the polarity reversal means reverses :.the polarity of the electrical current by adjusting the duty cycle such that the polarity of the portion of the cycle of the alternating current electrical potential is reversed. .02'S 8. A power supply substantially as described herein, with reference to the Figures 1 4,.t and 2 of the accompanying drawings, 9, A salt water chlorinator comprising a power supply according to any one of the preceding claims and a cell comprising a first and a second electrode capable of connection to the power supply and at least one additional electrode arranged between the first and second electrodes. A salt water chlorinator according to claim 9, wherein the first and second electrodes are disposed on opposing sides of the cell substantially parallel to one another.

11. A salt water chlorinator according to claim 10 wherein the or each additional electrode is arranged substantially parallel with the first and second electrodes.

12. A salt water chlorinator according to any on of claims 9 to 11, wherein the additional electrodes are arranged at regular intervals between the first and second electrodes.

13. A salt water chlorinator according to any one of claims 9 to 12, wherein the number of additional electrodes is between 1 and 11 inclusive.

14. A salt water chlorinator according tor any one of claims 9 to 13, wherein the electrodes are in the form of a plate.

15. A salt water chlorinator according to any one of claims 9 to 13, wherein the electrodes are in the form of a mesh. 15 16. A salt water chlorinator substantially as described herein, with reference to Figures 1 to 4 of the accompanying drawings. C DATED OCTOBER 25 1994 NEWBAH PTY LTD 20 By their Patent Attorneys KELVIN LORD AND COMPANY PERTH, WESTERN AUSTRALIA S 05 I ABSTRACT A power supply for a salt water chlorinator comprising a current control means, a timer means and a polarity of reversal means produces a phase controlled DC current and periodically reverses the polarity of the DC current. A delay timer is also disclosed which delays production of the DC current for a predetermined time after the power supply is activated. The DC current is adjustable in magnitude by the user. Also, a cell for a salt water chlorinator is disclosed. The cell comprises first and second electrodes connected to a power supply and a number of additional electrodes arranged at regular intervals between the first and second electrodes. The additional electrodes increase the efficiency of the cell without increasing the power consumed. S *S