Beverage brewing apparatus with constant temperature water reservoir

• US 4,531,046 A
• Filed: 01/10/1983
• Issued: 07/23/1985
• Est. Priority Date: 01/10/1983
• Status: Expired due to Term

• Current Assignee: Bunn-O-Matic Corporation
• Original Assignee: Bunn-O-Matic Corporation
• Inventors: Stover, Kenneth W.
• Primary Examiner(s): Bartis, A.
• Application Number:
  US06/456,735
• Time in Patent Office: 925 Days
• Field of Search: 219/296-299, 219/306-308, 219/283, 219/331, 219/328, 219/523, 99/279-282, 99/288, 99/305, 99/306, 99/304, 99/307
• US Class Current: 392/442
• CPC Class Codes: A47J 31/56 having water-level controls; having temperature controls

Abstract

A beverage brewing apparatus includes a hot water reservoir from which heated water is dispensed in predetermined serving volumes through a beverage filter to a serving beaker. A volume of cold water equal to a predetermined serving volume is admitted to a lower inlet zone of the reservoir, heated by an electric resistance heating element within the reservoir and dispensed in a volume equal to the serving volume from an upper outlet zone of the reservoir coincident with the introduction of cold water into the inlet zone. The reservoir has a volume greater than twice the predetermined serving volume so that a volume of resident heated water is contained in the central brew zone thereof. A temperature sensing element, e.g., thermistor, is disposed within the lumen of a hollow heat conductive tubing extending to a predetermined location in the brew zone at or near the center of the reservoir and produces a temperature control signal continuously indicative only of the temperature of the water in the brew zone. An electronic control circuit varies the duty cycle of the heating element over recurring timing intervals in response to the control signal to maintain the water in the brew zone at a predetermined temperature. The inlet and outlet zones correspond to the lower one-fourth and the upper one-fourth volumes, respectively, of the reservoir.

Claims

1. A beverage brewing apparatus comprising:

a hot water reservoir of predetermined volume;

means including a resistance heating element within said reservoir operable from an applied electric current for heating water in the reservoir;

inlet means for admitting a volume of cold water equal to a predetermined serving volume into an inlet zone at the bottom of said reservoir;

outlet means for discharging a volume of heated water equal to said predetermined serving volume from an outlet zone at the top of said reservoir coincident with the introduction of water by said inlet means into said reservoir;

said reservoir having a volume substantially greater than twice said predetermined serving volume whereby a volume of resident heated water is contained within a central brew zone thereof;

a segment of hollow heat-conductive tubing extending from a location at one end exterior to the reservoir to a predetermined location in said brew zone of said reservoir;

temperature sensing means disposed within the lumen of said tubing segment in thermal communication with said tubing segment at said predetermined location for producing a temperature control signal continuously indicative only of the temperature of the water at said predetermined location in said brew zone, and substantially non-indicative to the temperature of said water in said inlet and outlet zones; and

control circuit means responsive to said control signal for varying the duty cycle of the heating element over recurring timing intervals to maintain said water in said brew zone at a substantially constant predetermined temperature.

2. A beverage brewing apparatus as defined in claim 1 wherein said inlet zone corresponds to approximately the bottom 1/4 volume of said reservoir, and said outlet zone corresponds to approximately the top 1/4 volume of said reservoir.

3. A beverage brewing apparatus as defined in claim 1 wherein said inlet means include a tube extending vertically in said reservoir for conveying cold water to said inlet zone.

4. A beverage brewing apparatus as defined in claim 1 wherein said temperature sensing means comprise a thermistor.