Sous-vide cooker

Abstract

A sous-vide cooker is disclosed. The sous-vide cooker comprises a cooking chamber, a heating system, and a housing that houses the cooking chamber and the heating system. The cooking chamber comprises a chamber body, a multi-function lid, a passive water circulator and, optionally, a rack for holding food items during the cooking process. The heating system comprises a heating unit, one or more temperature sensors, a proportional-integral-derivative (PID) controller, and a control panel. The PID controller is calibrated. The sous-vide cooker maintains a constant water temperature within tolerances.

1 - 20 . (canceled) 
     
     
         21 . A sous-vide cooker for use with fluid, comprising:
 a chamber body having a bottom interior surface;   a heating unit;   one or more temperature sensors not in direct contact with any fluid inside the chamber body;   a proportional-integral-derivative (PID) controller; and   a control panel;   wherein said PID controller uses a temperature correction algorithm that implements a temperature conversion factor so that the temperatures measured by the one or more temperature sensors reflect actual fluid temperature in the chamber body, and wherein the heating unit heats the chamber body and the PID controller controls the temperature using the one or more temperature sensors and the heating unit.   
     
     
         22 . The sous-vide cooker of  claim 21 , further comprising a passive fluid circulator. 
     
     
         23 . The sous-vide cooker of  claim 22 , wherein the passive fluid circulator comprises a plate with a plurality of holes in the plate. 
     
     
         24 . The sous-vide cooker of  claim 22 , wherein the passive fluid circulator is located near the bottom interior surface of the chamber body. 
     
     
         25 . The sous-vide cooker of  claim 21 , further comprising a wire handle that is removably placed in the chamber body to facilitate removal of food items from the chamber body. 
     
     
         26 . The sous-vide cooker of  claim 21 , wherein when the chamber body is filled with fluid, the heating unit provides a fluid temperature in the range from about 5° C. above ambient temperature to about 95° C. with an accuracy of about 0.5° C. 
     
     
         27 . The sous-vide cooker of  claim 21 , wherein the heating unit comprises a flat heating plate or heating pad that is in contact with the chamber body. 
     
     
         28 . The sous-vide cooker of  claim 21 , wherein the one or more temperature sensors are attached to a lower portion of an exterior surface of the chamber body. 
     
     
         29 . The sous-vide cooker of  claim 21 , wherein there are two or more temperature sensors which are vertically spaced on the outside of the chamber body. 
     
     
         30 . The sous-vide cooker of  claim 21 , wherein the PID controller and the control panel are located in a thermally isolated control chamber to prevent overheating. 
     
     
         31 . The sous-vide cooker of  claim 21 , wherein said PID controller is programmed to perform the following calibration functions:
 allowing three temperature settings to be entered: temperature setting A, temperature setting B, and temperature setting C;   when the chamber body is filled with fluid, setting temperature setting A;   when a reference thermometer measures fluid temperature in the chamber body to obtain a first measured temperature after setting temperature A is reached on a PID display, allowing the difference between the setting temperature A and the first measured temperature as adjustment value A to be entered;   setting temperature setting B;   when the reference thermometer measures fluid temperature in the chamber body to obtain a second measured temperature after setting temperature B is reached on the PID display, allowing the difference between the setting temperature B and the second measured temperature as adjustment value B to be entered;   setting temperature setting C;   when the reference thermometer measures fluid temperature in the chamber body to obtain a third measured temperature after setting temperature C is reached on the PID display, allowing the difference between the setting temperature C and the third measured temperature as adjustment value C to be entered; and   storing, in memory, the adjustment values A, B and C.   
     
     
         32 . The sous-vide cooker of  claim 31 , wherein a setting temperature is maintained by said PID controller which is programmed to perform the following functions:
 obtaining a measured temperature in the chamber body using the one or more temperature sensors;   calculating the actual fluid temperature in the chamber body using a temperature offset subprogram using the stored adjustment value A, adjustment value B, and adjustment value C;   calculating a difference E (k)  between the setting temperature and the calculated actual temperature; and   calculating a control value U(k) for the heating unit.   
     
     
         33 . The sous-vide cooker of  claim 32 , wherein the PID controller contains a buzzer subprogram that provides an audio signal to the user if overheating is detected or if a set cooking time is reached. 
     
     
         34 . A control apparatus for a sous-vide cooker, the sous-vide cooker having a heating unit, one or more temperature sensors, and a chamber body for holding fluid, the apparatus comprising:
 a control panel; and   a proportional-integral-derivative (PID) controller comprising:
 a microprocessor; 
 a memory; and 
 a temperature correction algorithm; 
   wherein said PID controller is programmed to use the temperature correction algorithm to implement a temperature conversion factor so that the temperatures measured by the one or more temperature sensors reflect actual fluid temperature in the chamber body, and wherein the heating unit heats the chamber body and the PID controller controls the temperature using the one or more temperature sensors and the heating unit.   
     
     
         35 . The control apparatus of  claim 34 , wherein said PID controller is programmed to perform the following calibration functions:
 allowing three temperature settings to be entered: temperature setting A, temperature setting B, and temperature setting C;   when the chamber body is filled with fluid, setting temperature setting A;   when a reference thermometer measures fluid temperature in the chamber body to obtain a first measured temperature after setting temperature A is reached on a PID display, allowing the difference between the setting temperature A and the first measured temperature as adjustment value A to be entered;   setting temperature setting B;   when the reference thermometer measures fluid temperature in the chamber body to obtain a second measured temperature after setting temperature B is reached on the PID display, allowing the difference between the setting temperature B and the second measured temperature as adjustment value B to be entered;   setting temperature setting C;   when the reference thermometer measures fluid temperature in the chamber body to obtain a third measured temperature after setting temperature C is reached on the PID display, allowing the difference between the setting temperature C and the third measured temperature as adjustment value C to be entered; and   storing, in memory, the adjustment values A, B and C.   
     
     
         36 . The control apparatus of  claim 35 , wherein a setting temperature is maintained by said PID controller which is programmed to perform the following functions:
 obtaining a measured temperature in the chamber body using the one or more temperature sensors;   calculating the actual fluid temperature in the chamber body using a temperature offset subprogram using the stored adjustment value A, adjustment value B, and adjustment value C;   calculating a difference E (k)  between the setting temperature and the calculated actual temperature; and   calculating a control value U(k) for the heating unit.   
     
     
         37 . The control apparatus of  claim 36 , wherein the PID controller contains a buzzer subprogram that provides an audio signal to the user if overheating is detected or if a set cooking time is reached.