Automatic meter proving and calibration system

In a liquid dispensing apparatus including a housing, a mechanical flow measuring means in said housing for producing a flow indicating output signal in response to the passage of liquid therethrough, delivery pulser means responsive to said flow output signal for producing a plurality of output delivery pulses whose number has a predetermined proportional relationship to the volume of said dispensed, and data display means responsive to input pulses for indicating a dispensed volume of liquid in direct proportion to the number of input pulses received, wherein said ratio of output delivery pulses produced to the dispensed volume of said liquid varies over time according to mechanical wear and variations of said measuring means, a method of calibrating said data display means to compensate for said variations in the ratio of output delivery pulses produced to the dispensed volume of liquid, comprising the steps of:

• providing an indicating means within said housing for indicating the initiation of and completion of dispensation of a predetermined calibration volume of liquid, the number of input pulses necessary for said data display means to indicate said predetermined calibration volume being a known constant;
• counting said output delivery pulses during dispensation of liquid beginning with said initiation indication and ending with said completion indication;
• comparing said known constant to the count of output delivery pulses to determine a meter correction factor;
• modifying said plurality of output delivery pulses by said meter correction factor for use as input pulses to said data display means.

A liquid dispenser apparatus comprising:

• manually operable nozzle valve means for controlling dispensing of a liquid;
• pump means for supplying a flow of liquid to said nozzle valve means;
• mechanical flow meter means connected in circuit between said pump means and nozzle valve means for producing a meter output signal which is proportional to a dispensed volume of liquid passing through said flow meter means, said dispensed volume of liquid for a given meter output signal being variable over time due to mechanical wear and variations of said flow meter means;
• delivery pulser means, responsive to said meter output signal of said flow meter means, for producing a plurality of output delivery pulses whose number is directly proportional to said meter output signal;
• value display means, responsive to display input pulses, for displaying a volume value in direct proportion to the number of display input pulses received, said proportion representing a display constant;
• calibration means, including a calibration chamber of a predetermined calibration volume, for indicating dispensation of a volume of liquid substantially equal to said calibration volume;
• counting means, responsive to a signal from said calibration means, for counting the output delivery pulses produced during dispensation of a volume of liquid substantially equal to said calibration volume;
• and
• computer means for automatically computing a calibration factor based upon the number of delivery pulses counter during dispensation of said calibration volume of liquid, said display constant, and the displayed volume value of said dispensed calibration volume, the output delivery pulses produced during dispensation of a volume of liquid being modified by said computed calibration factor to display input pulses for delivery to said value display means, whereby said meter means is automatically compensated for variations in said meter output signal caused by mechanical wear and variations of said flow meter means, and whereby said value display means reflects an accurate value for the volume of liquid dispensed.

A liquid fuel dispensing apparatus comprising:

• a housing;
• liquid volume measuring means in said housing for providing a delivery signal corresponding to a dispensed volume of fuel;
• display means responsive to said delivery signal for displaying a dispensed volume of fuel;
• proving means in said housing for proving the amount of fuel dispensed during a predetermined number of dispensing operations of said apparatus and for providing a correction signal indicative of the difference between said displayed dispensed volume of fuel and the actual volume of dispensed fuel;
• and
• means for calibrating said display means based on said correction signal to cause said display means to indicate the actual volume of dispensed fuel.