DE19841568A1 - Automatic regeneration of washing up machine water softener - Google Patents

Abstract

A process to determine the optimum regeneration point for a programme-controlled domestic water softener using the electrical conductivity (L) of the rinsing fluid as detected by a sensor. The electrical conductivity (L) is measured both before and after the softener. The difference (delta L) is registered and compared with previous values of delta L from earlier treatment cycles. Initiation of the regeneration cycle is dependent upon the value of delta L detected.

Description

The invention relates to a method for determining the time of regeneration of a water Softening device, in particular for water-bearing program-controlled household appliances te, where the conductivity value determined by sensors is used to determine the hardness of the rinsing liquid Liquid is used. The invention also relates to an arrangement for implementation of the procedure.

Softening devices for the production of soft water from hard used or fresh water water, such as city or well water, are well known. Softeners are also known treatment facilities whose softeners work according to the ion exchange process, whereby the exhausted softeners must be regenerated with a salt brine. Such regenerable Ent Hardening devices are used both in central domestic water softening and esp especially with water-bearing household appliances such as dishwashers or washing machines machines used. The water softeners used in dishwashers are in the form of so-called monoblock softeners, each with an integrated salt container. To the The salt container of the softening device is usually a so-called water pocket for loading Upstream storage of retrievable amounts of regeneration water for regeneration brine treatment. The capacity of the softener is generally for a fresh or raw water hardness of up to 70 ° dH. designed. The soft water that can be removed from the softener for dishwashing is active nerated softener only has a low degree of hardness (e.g. 1 ° dH.), whereby 0 ° dH. achievable is. If the softener is exhausted, it is regenerated, with calcium ions in the ion exchanger be exchanged for sodium ions. So that soft water is available at all times, is regenerated at the end of a washing program, for example in dishwashers riert, whereby an amount of brine adjusted to the hardness of the raw water through the Softener is pressed. The ion exchange takes place here. The respective regeneration on End of a wash program, possibly for one or more further wash cycles A course of sufficient soft water hardness causes an increased consumption of salt. Furthermore is With this method it is necessary to set a hardness setting when setting up the device according to the local hot water hardness.

It is also known to measure and measure the amount of water used to wash dishes depending on the hardness of the fresh water supplied at a predetermined water level automatically initiate the regeneration process. This method be however, does not take into account fluctuations in the degree of hardness, so that here too much under certain circumstances Salt is consumed. Likewise, the machine must turn to the local domestic hot water hardness can be adjusted.

In machine dishwashing, it is also known that at low water hardness the The rinsing liquid used for dishwashing increases the risk of damage to the glass. This is in the we significant from a degree of hardness lower than 1 ° dH. (German hardship) the case. It is therefore it is also desirable to reduce the soft water produced to a certain minimum degree of hardness in order to reduce the attack on the glass to a minimum. Again, only so much salt should be used used for regeneration than is absolutely necessary.

It is also known in the case of water-bearing household appliances, the present degree of hardness of the Fresh water for the machine by means of a conductivity measurement in the water circuit assigned conductance sensors to determine and from it, for example, dosing instructions for the to derive the detergent to be used. To determine when to regenerate a softener processing device, however, such a method cannot be used. It is known that Frisch Water with great hardness usually also has a high conductivity and fresh water with less Hardness has a correspondingly lower conductance, and the conductance also depends on the Water temperature is dependent. This is the case with water softening in the dishwasher however, in such a way that, starting from very hard water, the inherently high conductance is maintained Water softening in the device changes towards the top. On the other hand, the low conductance will be if the water hardness is low, it is also increased by a small amount if the water is further softened. This behavior of conductivity can be there can be explained by that through the exchange of calcium ions by sodium ions the Leit value is increased.

The invention is based on the object of a simple method for exact determination to create the regeneration time regardless of fluctuating fresh water hardness, with which the regeneration is automatically set without having to adjust the system or the household appliance must be made to the local fresh water hardness, with Re generate the salt consumption is limited to the minimum and a minimum water hardness can be approved for a reduced glass attack.

According to the invention, this object is achieved by the method specified in claim 1 features resolved. Advantageous refinements and developments of the method result ben emerge from the following subclaims, the arrangement for performing the Method in claims 6 and 7 is characterized.

The advantages that can be achieved with the invention are in particular that there is no hardness It is necessary to use the existing fresh or service water when installing the device is, and that fluctuating network water hardnesses are automatically taken into account, where also the salt consumption as well as the glass attack by the heated rinsing liquid on a mini mum remains limited.

The invention is based on a method known per se for determining rain rierzeitpunktes a water softening device, especially for water-bearing rech nergesteuerte household appliances, the hardness of the washing liquid being determined by the egg The conductivity of the liquid determined by a sensor is used. Control such by program Erable dishwashers are well known in the literature and in practice. One can Softening device are used, which works according to the ion exchange process and in the manner of a monoblock softener with an integrated salt container within the dishwasher machine is trained. The monoblock softener, or in particular the salt container, is one So-called. Water pocket upstream in a manner known per se, which can be retrieved for storage rer regeneration water quantities for the purpose of processing brine depending on the raw water hardness of the fresh water supplied. The softener also supplies soft water a raw water hardness of up to 70 ° dH. One in each of the water-bearing program sections Washing program uses a certain amount of softened fresh or raw water as the washing liquid ability to clean the dishes directly from the outlet of the water softener into the rinsing container of the Dishwasher introduced. The time to regenerate the water softener is from depending on the monitored degree of exhaustion of the softening resin. The inventive The method is based on the knowledge that fresh water with great hardness has a greater lead worth than less hard fresh water.

In the water circuit of a known softening device is in front of and behind the softener a conductivity sensor is arranged, the sensors being connected to a memory the program control retrievable related comparison device and / or Control device are switched on. The comparison or control device takes action nerierzeitpunkt back to the program control of the household appliance.

According to the invention, the conductance is measured before and after the softener and a Conductance difference determined. However, since the conductance of the water is basically dependent on the water temperature is dependent, known temperature corrections, for example temperature compensations used.

A comparison with the measured conductance values and conductance difference values previously stored in the preferably non-volatile memory of the program control from a previous wash program or water-carrying wash program section is used to automatically determine and prompt when the softener is to be regenerated. It must be generated again if:
the conductance difference (ΔL) is equal to zero and the conductance (L) is greater than a predetermined limit value or the difference (ΔL) is not equal to zero and tends towards zero.
In this case, a conductivity value of, for example, equal to or greater than 0.8 mS / cm could be considered appropriate as the predetermined limit value from which the softener is to be regenerated in the event of a conductivity difference of zero.

The output conductance values and / or L-differences to be used for the calculation or comparison Limits can be made using diagrams of softener runs, starting from low Water hardness (e.g. 0 ° dH.) To the highest water hardness (e.g. 70 ° dH.) For city water or Determine or derive well water and store it in the memory in tabular form. Included a conductance in S / cm, mS / cm or in µS / cm is used. Also temperature-dependent Conductance values and their compensation coefficients can be saved.

The regeneration time is determined by a conductance difference threshold, which z. B. 0.2 ΔL _{according to Reg.} (E.g. measured in mS / cm).

The following measured values are made available by the conductivity sensors in front of and behind the softener:

• 1.) Absolute conductance (L), for example in µS / cm
• 2.) Conductance difference (ΔL), before and after the softener
• 3.) Gradient of the conductance difference (ΔL).

When the dishwasher is delivered, there is always some salt in the salt container of the water softening device and the water softener has not yet been run over. The following is recognized at the water inlet:

• a) ΔL (conductance difference) e.g. = 0 and conductance (L) as limit value, for example <0.8 mS / cm.

Naturally soft water flows, regeneration is not necessary

• b) ΔL = 0 and L large is ambiguous as a snapshot
  • b1) either: run over softener regenerate
  • b2) or: Softened soft water in the network does not regenerate

Decision b1) or b2) by .DELTA.L before

this state.

For example, if ΔL was not equal to 0 and approaching 0; then b1) Regenerate If ΔL was always 0, i.e. ϑΔL = 0; then b2) no regeneration

The exact regeneration time is determined by the ΔL threshold mentioned at the beginning, which is, for example, ΔL = 0.2 ΔL _{according to Reg} . The regeneration time could also be set with a smaller threshold value of, for example, 0.1 (ΔL _{after Reg.).} The regeneration takes place in a manner known per se, but very salt-saving due to the automatic determination of the correct point in time.

To ensure the low water hardness in order to reduce the attack on the glass, a Bypass can be arranged. This bypass bypasses the softener and doses the soft water water to harder fresh water in the rinsing container, so that the desired hardness is also set can. The cross-section of the bypass can be either constant or adjustable.

It is advantageous that hardness adjustments are no longer required when setting up the device fluctuating network water hardness are automatically taken into account and also recognized is that with soft fresh water through a house water that may be connected upstream of the device softening a regeneration of the device softener does not have to take place.

Claims (7)

1. A method and arrangement for determining the regeneration time of a water softening device, in particular for water-bearing program-controlled household appliances, the conductivity of the liquid determined by sensors being used to determine the hardness of the rinsing liquid, characterized in that the conductivity (L) is measured before and after the softener a difference in conductance (ΔL) is determined from this,
that by a comparison with the conductance values (L) and conductance difference values (ΔL) stored in a memory of the program control from previous measurements, a regeneration of the softener is initiated. 2. The method according to claim 1, characterized, that the regeneration is initiated when the conductance difference (ΔL) is equal to zero and the Conductance (L) is greater than a defined limit value or the difference (ΔL) is not equal to zero and strives towards zero. 3. The method according to claim 1 and 2, characterized, that the predetermined conductance (L), from which at a conductance difference (ΔL) of zero the Ent harder to regenerate, equal to or greater than the specified limit. 4. The method according to one or more of claims 1 to 3, characterized in that the regeneration time by a conductance difference of z. B. 0.1 (ΔL _{according to Reg.} ) Is set. 5. The method according to one or more of claims 1 to 4, characterized, that the memory for storing the conductance values (L) and conductance difference values (ΔL) a previous wash cycle is a non-volatile memory. 6. Arrangement for performing the method according to claim 1 and one or more of claims 2 to 5, with a softening device consisting of one by one Salt solution regenerable ion exchanger as a softener, characterized, that in the water circuit of the softening device in front of and behind the softener Conductance sensor is arranged, and with a ste can be called up in connection with the memory existing comparison device, which at the time of regeneration on the program control of the household appliance. 7. Arrangement for performing the method according to claim 6, characterized, that to ensure a minimum water hardness in order to reduce the attack on the glass Softener bypassed bypass with constant or adjustable cross-section provided is.