Control system and method of controlling a dishwashing machine

A control system for a conveyor-type dishwasher having a plurality of sequentially arranged work stations, each of said stations having means for performing an operation on ware items located therein such as washing, rinsing, drying and the like, a conveyor for carrying the ware items into said dishwasher, past each of said stations, and out of said dishwasher whereby each of the ware items has defined therefor a leading edge and a trailing edge, and a reference point defined adjacent said conveyor near the entrance for ware to said dishwasher, said control system comprising:

• means for defining a series of zones of equal size arranged sequentially along said conveyor in the direction of travel of the ware for movement with said conveyor;
• means for providing a count value having an initial count value and for increasing said value incrementally upon movement of each of said zones past said reference point to produce a changing count value;
• the distance along said conveyor from said reference point to the entrance to one of said stations being defined as a first integer number of said zones, and the distance along said conveyor from said reference point to the exit of said one station being defined as a second integer number of said zones;
• sensor means for sensing the presence of a leading edge and a trailing edge of a ware item as said ware item is moved past said reference point;
• and
• control means responsive to said sensor means and said count means for, upon sensing the presence of said leading edge, adding said first number to the current value of said count to produce a first start value and storing said first start value upon sensing the presence of said trailing edge, adding said second number to the current value of said count to produce a first stop value and storing said first stop value, and in the event an additonal stop value has been previously stored whose value is greater than or equal to said first start value but less than said first stop value, eliminating said additional stop value;
• said control means further being constructed to control the operation performing means at said one station such that upon the current value of said count becoming equal to said start value, operation within said one station is commenced, and upon the current value of said count becoming equal to said first first stop value, operation within said one station is halted.

A method of controlling a conveyor-type dishwasher having a plurality of sequentially arranged work stations for performing operations on ware items located therein comprising washing, rinsing, drying operations and a conveyor for carrying the ware items into said dishwasher, past each of said stations, and out of said dishwasher, whereby each of the ware items has defined thereon a leading edge and a trailing edge, the method comprising the steps of:

• defining a reference point along said conveyor near the entrance for ware to said dishwasher;
• defining a series of zones of equal size arranged sequentially along said conveyor in the direction of travel of the ware for movement with said conveyor;
• providing a count having an initial value and increasing said value incrementally for movement of each zone from said reference point to produce a changing current value;
• determining, as a first number of said zones, the distance from said reference point to the entrance to one of said stations, and as a second number of said zones, the distance from said reference point to the exit from said one station;
• sensing to detect the presence of a leading edge and a trailing edge of a ware item ware items as said ware item is moved past said reference point;
• upon detecting the presence of said ledging edge, adding said first number to the current value of said count to produce a start value, and storing said start value, upon detecting the presence of said trailing edge, adding said second number to the current value of said count to produce a first stop value and storing said first stop value and, in the event an additional stop value has been previously stored whose value is greater than or equal to said start value but less than said first stop value, eliminating said additional stop value;
• upon the current value of said count becoming equal to said first start value, commencing operation within said one station;
• and
• upon the current value of said count becoming equal to said stop value, halting operation within said one station.