Liquid purification or separation – Processes – Ion exchange or selective sorption
Reexamination Certificate
1999-11-16
2001-05-22
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
Processes
Ion exchange or selective sorption
C210S087000, C210S140000, C210S143000, C210S541000, C210S662000, C210S670000, C210S739000
Reexamination Certificate
active
06235200
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to rechargeable water conditioning apparatus (such as a general-purpose water softener, a water softener forming part of some larger apparatus, or a water filter). The invention also relates to a method of controlling recharging of such a water conditioning apparatus and to a recharging controller for such an apparatus.
BACKGROUND OF THE INVENTION
Such water conditioning apparatus is well known. For example, some forms of domestic water softeners employ a tank containing resin beads having a coating of sodium ions. Hard water from a supply such as the water main is passed through the tank, and the sodium ions on the beads are exchanged with calcium and magnesium ions in the water so as to soften the water. Eventually, the resin beads become exhausted of sodium ions, and it is then necessary to recharging, or regenerate, the apparatus. In a known recharging process, there are five phases: (1) water is passed to a tank containing common salt which dissolves to form brine; (2) the brine is passed into the tank of resin beads where it filters through the beads to recharge them by replacing the calcium and magnesium ions with sodium ions; (3) water is passed through the tank of resin beads to wash away any remaining brine; (4) water is passed through the tank of resin beads in the opposite direction to remove any dirt or sediments; and (5) water is forced through the tank of resin beads in the normal direction to pack the resin beads ready to return to service. In order to avoid interrupting the supply of water to the house, during the last four of these phases, the water softener is bypassed so that water can be supplied to the house directly from the water main. Because the supplied water is not then softened, it is desirable that the recharging process takes place during periods of low, or no, water usage. To deal with this, it is known to control the recharging process of the softener by a timer, and the regeneration sequence is initiated at regular intervals, for example in the early morning when water usage might be assumed to be at its lowest.
One problem with this known form of control is that the time set for initiation of the recharging cycle may not necessarily always be a time when water usage is at its lowest. Another problem is that, in the event of power failure, many less expensive designs of timer will require resetting in order to avoid the recharging cycles occurring at the wrong times, possibly unbeknown to the consumer.
Similar issues arise in relation to other water conditioning apparatus, such as water filters. Such filters may need to be periodically recharged by backwashing to remove deposits. While the recharging operation is being carried out, then either the supply of water to the consumer must be cut off, or the consumer must be supplied with unfiltered water.
A first aspect of the present invention is concerned more particularly with a method of controlling recharging of a water conditioning apparatus, comprising the steps of: detecting water usage by the apparatus; storing for each time slot of a cyclically repeating series of such time slots information about the usage in that time slot; and determining, at least in part, a time for recharging the apparatus in dependence upon the stored information. Such a method is hinted at in patent document GB-A-2,177,232, although it is not apparent from that document how, during normal operation, recharging can actually take place once a determination to recharge has been made.
In the method of GB-A-2,177,232, the duration of each time slot is one hour, and the time slots repeat every four weeks. If there has been no water usage in a particular time slot, then that fact is stored. It appears that recharging is supposed to take place once required and at a time when the stored information for the particular time slot indicates zero usage. To deal with the case where there is never zero usage, it appears that the time slot for which there has been minimum usage is also stored, and that recharging can supposedly also take place once required and when the stored minimum usage time slot occurs.
SUMMARY OF THE INVENTION
The method of the first aspect of the present invention is characterised in that the information which is stored for each time slot (for example of 3 hours duration) of the cyclically repeating series of such time slots (for example over a period of one week) is a value dependent. upon an average of the measured amounts of usage in that time slot and in at least one corresponding such time slot in a previous cycle. The storing of an amount of usage for each time slot, rather than a binary value (“usage” or “no usage”) opens up many possibilities for improving the method. Also, the use of average values for corresponding time slots makes the method less susceptible to vagaries in the water usage in one particular series of the time slots.
In a preferred example of normal operation, when the value for each time slot is updated, the new value may be calculated as the arithmetic mean of the measured amount during the time slot which has just elapsed and the value stored for that time slot. On the other hand, during initialisation (that is, until the time slots start repeating,) the value stored in each time slot may simply be the measured amount for that time slot.
In addition to determining a time for recharging the apparatus, the method may also determine different types of recharging process (for example a full recharging or a partial recharging) in dependence upon different conditions.
The method may further comprise the step of detecting a parameter from which a requirement to recharge the apparatus can be determined or predicted. For example, the total amount of water used since the previous discharge may be measured, and on the basis of this (and preferably also on a preset indication of the hardness of the water) and a predetermined value, a requirement value can be calculated, having a value of, say, 0% when the apparatus has just been recharged and a value of, say, 100% when it is predicted that the apparatus has no conditioning capacity remaining.
In one example of operation, in the determining step, the current time slot is determined to be such a time for recharging the apparatus if both (a) the stored value for the current time slot is a minimum compared with that for adjacent time slots and (b) the requirement parameter is in a first predetermined requirement range, for example greater than 75%. In this case, a full recharge may be initiated. Thus, a full recharge can be carried out at what can be predicted to be a good time based on historical usage.
In another alternative or additional example of operation, in the determining step, the current time slot is determined to be such a time for recharging the apparatus if both (a) the stored value for the current time slot is the minimum of the stored values for all of the time slots and (b) the requirement parameter is in a second predetermined requirement range, for example greater than 75%. In this case, also, a full recharge may be initiated. Thus, a full recharge can be carried out at what can be predicted to be the best, or a good, time of the week, based on historical usage.
In a further alternative or additional example of operation, in the determining step, the current time slot is determined to be such a time for recharging the apparatus if both (a) the measured water usage for the current time slot is less than a first predetermined usage value or even zero and (b) the requirement parameter is in a third predetermined requirement range, for example less than 90%. In this case, a partial recharge may be initiated. Thus, if the need to recharge the apparatus is becoming critical, despite the options for a full recharge mentioned above, a time of low or zero usage may be chosen for a partial (and therefore temporally short) recharge, irrespective of the historical usage.
In yet a further alternative or additional example of operation, in the determining step, the current time is determined
Drodge Joseph W.
Waterside PLC
Wolf Greenfield & Sacks P.C.
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