Dishwashing Machine With Heating Control

Abstract

A dishwashing machine for commercial use to clean items cyclically has at least one tank for holding a dishwashing liquid, as well as at least one heating apparatus for heating the dishwashing liquid, and at least one temperature sensor for detecting the temperature of the dishwashing liquid. The dishwashing machine also has a controller being designed in order to control heating of the dishwashing liquid in at least one program step in a dishwashing program, with the heating being carried out at least until a predetermined intended temperature is reached. In this case, before or during an initial heating phase, a start temperature of the dishwashing liquid is detected, the minimum heating duration being determined from the start temperature. The heating process is then carried out accordingly with this minimum duration.

1 . A dishwashing machine for commercial use to clean items to be cleaned in a dishwashing chamber cyclically, the dishwashing machine comprising at least one tank for holding a dishwashing liquid, at least one heating apparatus for heating the dishwashing liquid, at least one temperature sensor for detecting the temperature of the dishwashing liquid, and a controller operable to control heating of the dishwashing liquid in at least one program step in a dishwashing program, with the heating being continued at least until a predetermined intended temperature is reached, wherein, before or during an initial heating phase, a start temperature is detected, the minimum heating duration being determined from the start temperature and the heating is carried out accordingly using this minimum duration. 
     
     
         2 . The dishwashing machine as claimed in  claim 1 , wherein the controller is operable to detect a temperature of the dishwashing liquid once again after the minimum duration has elapsed, and in order to carry out a decision step, in which case, if the temperature is below the intended temperature or is below the intended temperature by more than a tolerance threshold, the heating is extended, and in which case, if the temperature has reached or exceeded the intended temperature, the heating is ended. 
     
     
         3 . The dishwashing machine as claimed in  claim 2 , wherein the controller is operable to carry out the temperature detection and the decision step once again if the temperature in the respective preceding decision step was below the intended temperature, or was below the intended temperature by more than a tolerance threshold. 
     
     
         4 . The dishwashing machine as claimed in  claim 1 , wherein the controller is operable to determine the minimum duration analytically or semi-empirically, with the amount of liquid in the dishwashing liquid to be heated, the thermal capacity of the dishwashing liquid to be heated, the temperature difference between the intended temperature and the start temperature, and the heating power of the heating apparatus being sensed and used as initial variables in this determination process. 
     
     
         5 . The dishwashing machine as claimed in  claim 4 , wherein the controller applies a correction value as a further initial variable, the correction value being designed in order to take account of any thermal loss from the dishwashing liquid during the heating process. 
     
     
         6 . The dishwashing machine as claimed in  claim 5 , wherein the correction variable is a temperature-dependent correction variable. 
     
     
         7 . The dishwashing machine as claimed in  claim 4 , wherein the correction variable comprises at least one of the following variables: a correction factor, a correction function; a correction characteristic. 
     
     
         8 . The dishwashing machine as claimed in  claim 5 , wherein the correction variable is stored in an electronic data memory. 
     
     
         9 . The dishwashing machine as claimed in  claim 1 , further comprising a circulation device for initial cleaning of the items to be cleared, and at least one final washing tank. 
     
     
         10 . The dishwashing machine as claimed in  claim 9 , wherein the at least one program step comprises a circulation step, and wherein the heating process is continued at least until the predetermined intended temperature in the washing tank is reached. 
     
     
         11 . The dishwashing machine as claimed in  claim 10 , wherein the controller detects the start temperature with a predetermined start delay with respect to the start of the circulation step. 
     
     
         12 . The dishwashing machine as claimed in  claim 11 , wherein the delay is in the range between 5 and 60 seconds, and preferably in the range between 10 and 20 seconds. 
     
     
         13 . The dishwashing machine as claimed in  claim 10 , wherein the controller is operable to continue the circulation step at least for a predetermined action time after the intended temperature has been reached. 
     
     
         14 . The dishwashing machine as claimed in  claim 9 , wherein the controller is operable to control heating a final washing liquid in the final washing tank during a circulation step. 
     
     
         15 . The dishwashing machine as claimed in  claim 14 , wherein the controller is operable to define the duration of the circulation step in accordance with the specific minimum duration of the heating of the final washing liquid. 
     
     
         16 . The dishwashing machine as claimed in  claim 15 , wherein the controller lengthens the duration of the circulation step in the decision step when the temperature of the final washing liquid ( 138 ) is below the intended temperature or is below the intended temperature by more than a tolerance threshold. 
     
     
         17 . The dishwashing machine as claimed in  claim 9 , further comprising a pressure increasing pump for increasing the pressure of the final washing liquid during the final washing process and/or a fresh water connection for supplying pressurized fresh water to the final washing tank in order to increase the pressure during the final washing process. 
     
     
         18 . A method for controlling a dishwashing machine for commercial use, the method comprising heating dishwashing liquid in at least one tank in at least one program step in a dishwashing program, continuing the heating process at least until a predetermined intended temperature is reached, detecting a start temperature before or during an initial heating phase, determining the minimum heating duration from the start temperature, and heating the dishwashing liquid during this minimum duration. 
     
     
         19 . The method as claimed in  claim 18 , further comprising again detecting the temperature of the dishwashing liquid after the minimum duration has elapsed and step being carried out, in which case, if the temperature is below the intended temperature or is below the intended temperature by more than a tolerance threshold, extending the heating, or if the temperature has reached or exceeded the intended temperature, ending the heating. 
     
     
         20 . The method as claimed in  claim 19 , with the temperature detection and the process of carrying out the decision step being carried out repeatedly if the temperature in the respective preceding decision step was below the intended temperature, was below the intended temperature, or was below the intended temperature by more than a tolerance threshold.