Method for the energy-saving, continuous measuring of a quality of a liquid and measuring device for carrying out the method

1 . A method for energy-saving, continuous measuring of a quality of a liquid using a measuring device having a sensor for detecting a measurement variable in the liquid, wherein:

S 1 ) the measuring device is arranged relative to the liquid and the sensor detects the measurement variable in the liquid;

S 2 ) the sensor is alternatingly activated for a duration of a switch-on phase and deactivated for a duration of a switch-off phase;

S 3 ) a switch-on phase in a steady state of the sensor is defined as a defined switch-on phase and a measurement value is detected as a comparison measurement value by the sensor during the defined switch-on phase when a value of the measurement variable differs by at most a predetermined difference from a value of the measurement variable during a previous switch-on phase;

S 4 ) a reference measurement is carried out to detect a reference measurement value representing a reference quality of the liquid;

S 5 ) during further switch-on phases following the defined switch-on phase, the sensor continuously detects measurement values in the liquid as operating measurement values representing operating qualities of the liquid;

S 6 ) a calculation rule assigns the comparison measurement value to correspond to the reference measurement value; and

S 7 ) a final measurement value representing a final quality of the liquid is determined based on the calculation rule and each of the operating measurement values; wherein

in order to carry out the reference measurement

S 4 b ) the defined switch-on phase or a switch-on phase between the defined switch-on phase and the further switch-on phases for detecting the operating measurement values is extended compared to the preceding switch-on phases, and during the extended switch-on phase the reference measurement value is detected using the sensor.

2 . The method according to claim 1 , wherein the sensor is periodically activated and deactivated at least temporarily.

3 . The method according to claim 1 , wherein

S 3 a ) a switch-on phase is defined as the defined switch-on phase at least when a determined number of previous switch-on phases follow an extended switch-off phase that is longer than the duration of the switch-off phase or follow a first-time activation of the sensor.

4 . The method according to claim 1 , wherein

S 3 b ) a switch-on phase is defined at least by the following as the defined switch-on phase:

detecting measurement values with the sensor in a plurality of consecutive switch-on phases;

comparing the most recently detected measurement value with the previously detected measurement value; and

in the case of a deviation of the two compared measurement values from each other which deviation falls below a predefined threshold value, defining the switch-on phase for the last measurement value as the defined switch-on phase.

5 . The method according to claim 1 , wherein the comparison measurement value and/or the operating measurement value are detected by measuring the comparison measurement value and/or the operating measurement value at a determined target point in time within the switch-on phase.

6 . The method according to claim 5 , wherein the determined target point is an end of the switch-on phase.

7 . The method according to claim 1 , wherein the comparison measurement value and/or the operating measurement value are detected by:

measuring with the sensor at a plurality of points in time within the switch-on phase associated with the comparison measurement value and/or operating measurement value in order to obtain a plurality of sampled values;

calculating a measurement value progression approximated to the sampled values within the switch-on phase;

measuring at what actual point in time the comparison measurement value and/or operating measurement value intended for the measurement at a defined target point in time was actually measured; and

in the event of a deviation of the actual point in time from the target point in time, calculating the comparison measurement value and/or operating measurement value at the target point in time by means of the approximated measurement value progression.

8 . The method according to claim 1 , wherein

the calculation rule assigns the comparison measurement value to correspond to the reference measurement value so as to determine a constant factor, which is formed from a quotient between the comparison measurement value and the reference measurement value, and

the final measurement value is determined for each of the operating measurement values by dividing each of the operating measurement values by the calculated constant factor.

9 . The method according to claim 1 , wherein

S 8 ) the steps S 2 ) to S 7 ) are carried out again if a plurality of operating measurement values compared with one another or a plurality of final measurement values compared with one another deviate from one another by more than a predefined threshold value.

10 . The method according to claim 1 , wherein

S 9 ) at least the steps S 2 ), S 3 ) and S 5 ) to S 7 ) are carried out again if the duration of the switch-on phase and/or the duration of the switch-off phase has been changed by more than a predefined threshold value.

11 . The method according to claim 1 , wherein

S 10 ) a liquid pump of the measuring device, which liquid pump conducts the liquid over the sensor, is already activated before the sensor, for example, is activated one minute to two minutes before step S 2 ), and is activated before the sensor for a period of time sufficient to supply the liquid to the sensor.

12 . The method according to claim 1 , wherein a sensor for measuring the concentration of a disinfectant, for measuring a chlorine concentration, or for measuring a pH value, is used as the sensor.

13 . A measuring device for the energy-saving continuous measurement of a quality of a liquid comprising at least one sensor, an electric power storage means and a controller, wherein the controller is configured to carry out a method according to claim 1 .

14 . The measuring device according to claim 13 , wherein the sensor is configured to measure the concentration of a disinfectant, to measure a chlorine concentration, or to measure a pH value.