Fryer temperature control system
AssigneePremark FEG L.L.C.
InventorsRichard W. Cartwright, Joseph A. Lang, Jr., Raymond M. Lepore
Life of this patent
Estimating the term…
Abstract
An oil fryer control system simultaneously controlling oil temperature and cooking time. A proportional, integral and derivative temperature control is used to maintain the oil temperature below and above a predetermined set point temperature. In addition, a cooking time control varies the cooking time within a predetermined range of temperature error as a function of a stored time-temperature relationship. The invention provides the capability of cooking different products having different cooking parameters in the same or different oil vats.
Claims22
A fryer comprised of at least one vat of oil for cooking a product, a heating means for heating the oil and a fryer control comprising:
- a. means for storing at least one set of cooking data for a product, said cooking data defining a predetermined oil temperature and a predetermined cooking time;
- b. means for producing an oil temperature signal representing a current oil temperature;
- c. means responsive to the oil temperature signal and the cooking data for providing a temperature error signal as a function of the difference between the current oil temperature and the predetermined oil temperature;
- d. means responsive to the temperature error signal for producing a heater control signal representing a desired duty cycle of the heater, said heater control signal being determined as a function of a current temperature error signal, a sum of a predetermined number of successive temperature error signals and a sum of changes between the successive temperature error signals;
- e. means for storing a cooking time control function relating a change in cooking time to temperature error within a predetermined range of temperature error greater than and less than the predetermined oil temperature;
- f. means responsive to the temperature error signal and the cooking time control function for providing a cooking time clock signal having a frequency varying proportion to the temperature error signal;
- and
- g. means responsive to the predetermined cooking time for counting the predetermined cooking time, said counting means being responsive to the cooking time clock signal whereby the counting means counts the predetermined cooking time at a frequency varying as a function of the temperature error signal.
A method for operating an oil fryer having at least one vat of oil, an oil heater, temperature sensing means producing a signal as a function of oil temperature and a fryer control for controlling oil temperature and cooking time of a product in the fryer, the method comprising the steps of:
- a. storing selectable cooking data for products to be cooked, said selectable cooking data for a first product including a predetermined oil temperature and a predetermined cooking time, said predetermined cooking time representing a predetermined number of increments;
- b. sampling the signal produced by the temperature sensing means to determine a current oil temperature;
- c. detecting selection of selectable cooking data for the first product;
- d. determining a temperature error in response to the current oil temperature and the predetermined oil temperature;
- e. calculating a desired duty cycle of the oil heater as a function of the temperature error, a sum of a predetermined number of successive temperature errors and a sum of changes between the successive temperature errors;
- f. applying power to the oil heater for a period of time defined by the desired duty cycle thereby causing the current oil temperature to be approximately equal to the predetermined oil temperature;
- and
- g. generating a cooking cycle in response to detecting selection of the selectable cooking data for the first product, said cooking cycle having a duration proportional to the predetermined cooking time and the temperature error, and during said cooking cycle
- i) producing a clock signal having a frequency dependent on the temperature error,
- ii) counting the increments of the predetermined cooking time in response to the clock signal, and
- iii) producing a cooking done signal in response to counting the predetermined number of increments of the predetermined cooking time.
A method for operating an oil fryer having at least one vat of oil, an oil heater, temperature sensing means producing a signal as a function of oil temperature and a fryer control for controlling oil temperature and cooking time of a product in the fryer, the method comprising the steps of:
- a. storing selectable cooking data for products to be cooked, said selectable cooking data for a first product including a predetermined oil temperature and a predetermined cooking time, said predetermined cooking time representing a predetermined number of increments;
- b. generating first time intervals and during each of said first time intervals sampling the signal produced by the temperature sensing means to determine a current oil temperature;
- c. detecting selection of selectable cooking data for the first product;
- d. generating second time intervals and during each of said second time intervals
- i. determining a temperature error in response to the current oil temperature and the predetermined oil temperature;
- and
- ii. calculating a desired duty cycle of the oil heater as a function of the temperature error, a sum of a predetermined number of successive temperature errors and a sum of changes between the successive temperature errors;
- e. applying power to the oil heater for a period of time defined by the desired duty cycle thereby causing the current oil temperature to be approximately equal to the predetermined oil temperature;
- and
- f. generating a cooking cycle in response to detecting selection of the selectable cooking data for the first product, said third time intervals having a duration proportional to the predetermined cooking time and the temperature error, and during each of said third time intervals
- i) producing a clock signal having a frequency dependent on the temperature error,
- ii) counting the increments of the predetermined cooking time in response to the clock signal, and
- iii) producing a cooking done signal in response to counting the predetermined number of the increments of the predetermined cooking time.
Dependencies are inferred from the claim text.