Control system for automatic coffee brewing machines

• US 4,155,291 A
• Filed: 08/30/1978
• Issued: 05/22/1979
• Est. Priority Date: 08/30/1978
• Status: Expired due to Term

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: General Electric Company
• Inventors: Ryckman, William D. Jr., Kemp, Charles L.
• Primary Examiner(s): Jenkins, Robert W.
• Application Number:
  US05/938,030
• Time in Patent Office: 265 Days
• Field of Search: 99/280, 99/281, 99/282, 99/283, 99/288, 99/300, 99/307, 219/441, 219/446, 219/296
• US Class Current: 99/282
• CPC Class Codes: A47J 31/0573 with flow through heaters flow through heaters as part of a water boiling vessel in a beverage making machine A47J31/542
• CPC Class Codes: A47J 31/54 Water boiling vessels in beverage making machines

Abstract

An automatic coffee brewing machine is provided with a heater for heating the pump apparatus for forcing water therethrough, thermostatic switch means associated with the pump apparatus for sensing the completion of the brewing cycle, and circuit means including the switch means effective upon completion of the brewing cycle for changing the power output of the heater from the high level required for brewing operation to a much lower level required to prevent reinitiation of the brewing cycle. A heating unit for a carafe holding brewed coffee has heating means associated with the circuit means for producing heat both during and after the brewing cycle, the heat produced during the brewing cycle being greater than that produced after the brewing cycle.

Claims

1. In an automatic coffee brewing machine of the type having a container for receiving cold water at the start of a brewing operation, a carafe for receiving brewed coffee at the end of the brewing operation, a pump assembly for forcing water between the container and the carafe, and a warming unit for receiving the carafe for keeping coffee therein hot, an improved heating and control system comprising:

a first heater in heat transfer relation with the pump assembly for heating water therein, second and third heaters for supplying heat to the warming unit,

thermostatic switch means in heat transfer relation with said pump assembly for sensing the temperature of said pump assembly, said switch means having a closed position and an open position and being actuated to said closed position whenever the sensed temperature is below a first predetermined level and being actuated to said open position whenever the sensed temperature is above a second higher predetermined level,

circuit means for interconnecting said first, second and third heaters and said switch means across a source of electric power such that at least a circuit consisting of said first and second heaters is connected in series across the source when said switch means is in its closed position and such that only a circuit consisting of said first and third heaters is connected in series across the source when said switch means is in its open position, the resistances of said first, second and third heaters being selected such that during the brewing operation the heat produced by said first heater is sufficient to pump water through the pump assembly without actuating said switch means to its open position and the heat produced by said second and third heaters is sufficient to heat said carafe and maintain coffee therein warm, and such that upon completion of the brewing operation the heat produced by said first heater is sufficient to heat the pump assembly to a temperature above the second predetermined level and thereby activate said switch means to its open position; and

the resistances of said first and third heaters being selected such that when the switch means has been actuated to its open position the heat produced by said first heater is sufficient to maintain said switch means in and the heat produced by said third heater is sufficient to maintain the carafe and coffee therein warm,

whereby said first heater prevents the machine from recycling following completion of the brewing operation.

2. A heating and control system as defined by claim 1 in which the resistance of said third heater is substantially greater than the resistance of said first heater and in which the resistance of said first heater is substantially greater than the resistance of said second heater.

3. A heating and control system as defined by claim 2 in which the resistance of said first, second and third heaters are selected such that the heat produced by said second and third heaters when said switch means is actuated to its closed position is greater than the heat produced by said third heater when said switch means is actuated to its open position.