Electronic thermostat for liquid heating apparatus

• US 7,263,283 B2
• Filed: 11/07/2003
• Issued: 08/28/2007
• Est. Priority Date: 11/08/2002
• Status: Expired due to Fees

• Current Assignee: Bunn-O-Matic Corporation
• Original Assignee: Bunn-O-Matic Corporation
• Inventors: Knepler, John T.
• Primary Examiner(s): Leung; Philip H.
• Assistant Examiner(s): PATEL, VINOD D
• Application Number:
  US10/534,195
• Publication Number:
  US 20050271372A1
• Time in Patent Office: 1,390 Days
• Field of Search: 392/498, 392441-442, 392/448.14, 392/497, 398/448.16, 219/482, 219/488, 219/491
• US Class Current: 392/498
• CPC Class Codes: A47J 31/56 having water-level controls; having temperature controls
• CPC Class Codes: G05D 23/1909 whose output amplitude can only take two discrete values
• CPC Class Codes: H05B 1/0269 For heating of fluids

Abstract

An electronic thermostat (20) has a mechanical switch (22) and a solid-state switch (24). The electronic thermostat (20) is suitable for use in a liquid heating apparatus, such as a coffee maker or any other apparatus that dispenses heated beverages. In an illustrative embodiment, the electronic thermostat (20) has a controller (36) and a temperature sensor (34).

Claims

1. An electronic thermostat of a heated beverage dispenser having a container in which liquid is contained and a heater that is operable by electrical power to heat the liquid, the electronic thermostat comprising:

a mechanical switch through which electrical power is applied to the heater to increase a temperature of the liquid from an initial temperature toward a target temperature;

a solid-state switch in parallel with the mechanical switch through which electrical power is applied to the heater to maintain the temperature of the liquid at substantially the target temperature; and

a controller, wherein the controller is programmed to implement a partial or complete proportional-integral-derivative algorithm for controllably heating liquid to produce a beverage, the controller being coupled to the mechanical switch and the solid-state switch.

2. The electronic thermostat of claim 1 further comprising a temperature sensor that senses the temperature of the liquid in the container and provides feedback to the controller.

3. The electronic thermostat of claim 1 further comprising a sensor that senses the level of the liquid in the container and provides feedback to the controller.

4. A method of heating a beverage dispenser, the method comprising:

operating a mechanical switch to a closed circuit mode to apply power to a heater to heat the liquid from an initial temperature toward a target temperature, then opening the mechanical switch; and

operating a solid-state switch to a closed circuit mode to apply power to the heater to maintain the liquid substantially at the target temperature;

wherein the mechanical switch in parallel with the solid-state switch and are controlled by, and coupled to a controller and wherein the controller is programmed to implement a partial or complete proportional-integral-derivative algorithm for controllably heating liquid to produce a beverage.

5. The apparatus of claim 4 wherein the target temperature is approximately 200 degrees Fahrenheit.

6. The apparatus of claim 4 wherein the liquid is maintained at a temperature in the range of 180-210 degrees Fahrenheit.

7. A beverage brewing apparatus comprising, an electronic thermostat, a heated beverage dispenser having a container in which liquid is contained and a heater that is operable by electrical power to heat the liquid, the electronic thermostat comprising:

a mechanical switch through which electrical power is applied to the heater to increase a temperature of the liquid from an initial temperature toward a target temperature;

a solid-state switch in parallel with the mechanical switch through which electrical power is applied to the heater to maintain the temperature of the liquid at substantially the target temperature; and

a controller, wherein the controller is programmed to implement a partial or complete proportional-integral-derivative algorithm for controllably heating a liquid to produce a beverage, the controller being coupled to the mechanical switch and the solid-state switch.

8. A method of heating a liquid in a heated beverage dispenser, the method comprising:

operating a mechanical switch to apply power to a heater to heat the liquid from an initial temperature toward a target temperature;

operating a solid-state switch in parallel with the mechanical switch to apply power to the heater to maintain the liquid substantially at the target temperature; and

the mechanical switch and the solid-state switch being controlled by, and coupled to a controller, wherein the controller is programmed to implement a partial or complete proportional-integral-derivative algorithm for controllably heating liquid to produce a beverage.

9. An electronic thermostat kit in combination with a heated beverage dispenser having a container in which liquid is contained and a heater that is operable by electrical power to heat the liquid, the electronic thermostat kit comprising:

a mechanical switch through which electrical power is applied to the heater to increase a temperature of the liquid from an initial temperature toward a target temperature;

a solid-state switch in parallel with the mechanical switch through which electrical power is applied to the heater to maintain the temperature of the liquid at substantially the target temperature; and

a controller, wherein the controller is programmed to implement a partial or complete proportional-integral-derivative algorithm for controllably heating liquid to produce a beverage, the controller being coupled to the mechanical switch and the solid-state switch.

10. An electronic thermostat in combination with a heated beverage dispenser having a container in which liquid is contained and a temperature modifier that is operable by electrical power to at least one of heat or cool the liquid, the electronic thermostat comprising:

a mechanical switch through which electrical power is applied to the temperature modifier to change a temperature of the liquid from an initial temperature toward a target temperature;

a solid-switch in parallel with the mechanical switch through which electrical power is applied to the temperature modifier to maintain the temperature of the liquid at substantially the target temperature; and

a controller, wherein the controller is programmed to implement a partial or complete proportional-integral-derivative algorithm for controllably heating liquid to produce a beverage, the controller being coupled to the mechanical switch and the solid-state switch.

11. A liquid beverage heating apparatus comprising;

a container for the liquid beverage;

a heater inside the container, the heater being operable by electrical power to heat the liquid in the container;

an electronic thermostat comprising;

a mechanical switch through which electrical power is applied to the heater to increase a temperature of the liquid from an initial temperature toward a target temperature;

a solid-state switch in parallel with the mechanical switch through which electrical power is applied to the heater to maintain the temperature of the liquid at substantially the target temperature; and

a controller, wherein the controller is programmed to implement a partial or complete proportional-integral-derivative algorithm for controllably heating liquid to produce a beverage, the controller being coupled to the mechanical switch and the solid-state switch.

12. The apparatus of claim 11, further comprising;

anti-arcing measuring device for closing the mechanical switch to prevent arcing between the contacts of the mechanical switch.

13. The apparatus of claim 12, wherein the anti-arcing measuring device includes means closing the solid-state switch briefly before applying electrical power to the heater by closing the mechanical switch.

14. The apparatus of claim 11, wherein the mechanical switch is of lower resistance than the solid-state switch.

15. The apparatus of claim 11 further comprising a temperature sensor that senses the temperature of the liquid in the container and provides feedback to the controller.

16. The electronic thermostat of claim 11 further comprising a sensor that senses the level of the liquid in the container and provides feedback to the controller.

17. The apparatus of claim 11, wherein the target temperature is approximately 200 degrees Fahrenheit.

18. The apparatus of claim 11, wherein the liquid is maintained at a temperature in the range of 180-210 degrees Fahrenheit.