Method and Apparatus for Automated Chinese Stir-Fry Cooking

This invention relates to Chinese cooking and specifically to a method and apparatus that a restaurant might use for automated Chinese stir-fry cooking which does not require the operator to possess knowledge or skills in the art of Chinese stir-fry cooking. This invention incorporates steps including entering and storing recipe data, selection of a recipe from a menu, addition of food and liquid ingredients at the proper intervals, temperature control throughout the cooking process, stirring of the cooking food, and timing of the cooking process, all performed automatically by a computer control system.

Chinese stir-fry cooking is the brisk cooking of small cuts of meats and vegetables in hot oil over intense heat, calling for split-second timing and swift movements in an uninterrupted rhythm. It is the most common method of cooking Chinese food and means literally "toss-cooked". Two elements are crucial to stir-frying. Firstly, thorough organization, in the sense that everything needed is within reach so no interruption will disturb the cooking once it starts; and secondly, vigilance from the chef who must be ready to measure and add ingredients, and adjust timing and volume of heat instantly. Each dish is allowed to cook for only one to four minutes. This cooking process requires considerable skill with the chef judging the progress of the dish by the smell, look and feel of the food and the sound of the cooking. Each order is cooked individually. At the completion of the cooking process, the chef scoops the cooked food onto a serving dish, cleans the cooking pan, and prepares to cook the next order. Because of the required knowledge and skill, many Chinese chefs begin their training at a young age and specialize in a regional style of cooking such as Cantonese or Szechwanese. Virtually all Chinese restaurants are operated by Chinese families who compete for the good chefs. J. B. Bakos, Editor of the trade magazine Restaurant Business, has written: "It is interesting to note that we have not seen the development of a Chinese restaurant chain". One reason for this is that a good Chinese restaurant is dependent on its chef, and a chef's span of control rarely exceeds one restaurant. Were there a way to capture and multiply the knowledge and the skills of a good Chinese chef, a whole new opportunity would be created for expansion in the Chinese restaurant industry.

Accordingly, several objects of this invention are: (1) to provide a method and apparatus by which an operator without Chinese cooking skills or knowledge can cook consistent, superior Chinese stir-fry dishes, (2) to increase the level of productivity over that of even the skilled Chinese chef by allowing the operator of this invention to cook several dishes concurrently, (3) to provide for cooking a wider range of regional stir-fry dishes than is commonly found in the repertoire of the traditional Chinese chef, to include the styles of Canton, Hunan, Peking, Shanghai and Szechwan. Further objects and advantages of this invention will become apparent from a consideration of the drawings and descriptions which follow.

The method and apparatus of this invention include the following interrelated components:

(a) a Chinese stove with gas burner;

(b) a wok with means for rotation about its vertical axis during the cooking process; as used in this description and in the appended claims, the term "wok" means a bowl-shaped cooking pan;

(c) a food tray with a rotatable divider for holding and dispensing food ingredients into the wok in predetermined time sequences;

(d) a spatula with driving means for stirring and tossing the food as it cooks;

(e) a plurality of liquid dispensers for holding and dispensing liquid ingredients into the wok in predetermined quantities and in predetermined time sequences;

(f) a temperature measuring component for measuring the temperature of the wok throughout the cooking process;

(g) a gas valve for controlling a supply of gas to the gas burner;

(h) a computer control system for storing, displaying and processing recipe information, for activating and deactivating the means to rotate the wok, the means to drive the spatula, the means to rotate the rotatable divider of the food tray, for activating and deactivating the plurality of liquid dispensers, for activating and deactivating the gas valve, and for receiving temperature measurements from the temperature measuring component.

The method and apparatus of this invention performs the entire cooking process automatically. The operator selects a recipe from a displayed menu, mounts a corresponding food tray, and presses a "start" key. When the cooking is complete, the operator scoops the food onto a serving dish, replaces the wok and spatula with clean utensils, and is ready to repeat the process for the next order. The computer control system under program instructions heats the wok, adds and stirs the food, times the cooking, measures and adds liquid ingredients and regulates the heat, all according to the recipe selected. The computer control system accommodates a multiplicity of recipes each of which may be individually varied by the person preparing the recipes. New recipes may be added to the computer control system using a straightforward cookbook notation. Furthermore, by operating several of these inventions, a single operator may cook several orders concurrently.

For an illustration of the construction and operation of the preferred embodiment, reference is made to the attached several views wherein identical reference numbers are utilized to refer to identical or equivalent components throughout the several views.

FIG. 1 is a front elevation view of the overall assembly.

FIG. 2 is a side elevation view of the spatula with driving means for stirring and tossing the food as it cooks.

FIG. 3 is a side elevation view of the food tray with rotatable divider for holding and dispensing food ingredients into the wok.

FI. 4 is a side elevation view of the plurality of liquid dispensers for holding and dispensing liquid ingredients into the wok.

FIG. 5 is a side elevation view of the wok with means for rotation about a vertical axis, and the temperature measuring component for measuring the temperature of the wok.

FIG. 6 is a "filled-out" recipe worksheet used for preparing a recipe to be entered into the computer control system.

FIG. 7 and FIG. 8 are program structure flowcharts illustrating the program logic of the computer control system.

FIG. 9 is a schematic diagram of the computer control system interface.

For a description of the construction and utilization of this method and apparatus, reference is made to the attached drawings. This applicant has constructed, tested and extensively experimented with a fully operational prototype of this invention in his kitchen at home.

The construction of the apparatus begins with a conventional Chinese stove 8 of FIG. 1 as used in Chinese restaurants and a wok 9 of FIGS. 1 and 5. In conventional usage of the Chinese stove, the wok is stationary over a gas burner 10. A Chinese chef controls the heat by a manual gas valve 52. The air and gas mixture to the gas burner is adjustable by two air/gas mixture valves 51. In the apparatus of this invention the wok rests on a metal collar 11 rotatably supported over the gas burner. The collar is operably attached to the top of a vertical pipe 12. The vertical pipe passes downward through the center of the gas buner 10, and is rotatably supported beneath the gas burner by a ball bearing pillow block 13. The ball bearing pillow block is operably mounted to the framework 14 of the Chinese stove. A first motor means 15, operably coupled to the vertical pipe, rotates the vertical pipe thereby rotating the collar and the wok. The first motor means is activated and deactivated by signals from a computer control system to be subsequently described.

A food dispensing component illustrated in FIG. 3, is comprised of a food tray 16, a rotatable divider 17 which fits in the food tray and which partitions the food tray into a plurality of compartments 18, a tray arm 19 which projects horizontally over the wok, a first base 20 which supports the tray arm, a tray spindle 21 rotatably mounted vertically on the tray arm over the wok, a second motor means 22 operably mounted on the first base, a first driving means 23 which operably couples the second motor means to the tray spindle. The food tray is comprised of a round pan with bottom means having a hole in the center thereof and a sector-shaped opening thereof 24. The rotatable divider is comprised of a plurality of panels 25 which radiate outward from a hub 26. A keyed mounting ring 27 is operably attached to the bottom of the hub. The tray spindle has a keyed tip matching the keyed mounting ring. The food tray containing the rotatable divider is removably mounted upright on the tray spindle by the operator with the tray spindle fitting through the hole in the bottom means of the food tray and into the keyed mounting ring on the bottom of the hub of the rotatable divider. The second motor means is activated by signals from the computer control system.

When activated, the second motor means rotates the first driving means to rotate the tray spindle thereby turning the rotatable divider. This rotation moves the food ingredients, in the compartment adjacent to the sector-shaped opening in the food tray, over the sector-shaped opening where, by gravity, the food ingredients fall into the wok. The amount of rotation is a predetermined quantity programmed in the computer control system. At the end of the predetermined rotation the computer control system deactivates the second motor means. This allows the food ingredients in each compartment to be dispensed into the wok in a predetermined sequence and in predetermined intervals by signals from the computer control system. A further detail of the food tray is a catch means 28 operably attached to the food tray which engages a stop means 29 operably attached to the tray arm when the food tray with rotatable divider is mounted on the tray spindle. This prevents the food tray from turning when the rotatable divider turns.

The components for stirring the food and liquid ingredients, illustrated in FIG. 2, is comprised of a spatula 30 with a blade 31 and a handle 32, a spatula arm 33, a vertical reciprocating linear motion means 34, a third motor means 35, a second base 36 on which the third motor means is mounted, a second driving means 37 for coupling the third motor means to the vertical reciprocating linear motion means, a cam 38, a rotatable cam rod 39, a cam rod support means 40, a third driving means 41 for coupling the cam to the third motor means. The spatula is removably connected pivotally at the handle to the spatula arm. The spatula arm is operably attached to the vertical reciprocating linear motion means. The vertical reciprocating linear motion means is operably coupled to the second driving means. The second driving means is operably coupled to the third motor means. This coupling converts the rotary motion of the third motor means to a vertical reciprocating linear motion of the spatula arm. On the downward motion of the spatula arm the blade of the spatula sweeps down the inside surface of the wok until reaching just past bottom center of the wok. The blade of the spatula is biased against the inside surface of the wok by a spring means 42 operably attached removably to the handle of the spatula and operably attached to the other end to the spatula arm. When the blade of the spatula reaches just past bottom center of the wok the movement of the spatula arm reverses direction and draws the blade of the spatula back to its initial position at the inside edge of the wok.

As the blade of the spatula is drawn back, the cam, positioned directly beneath the spatula handle, rotates to make contact with the spatula handle. On contact, the cam lifts the spatula up from the inside surface of the wok as the spatula is drawn back. With the wok rotating, the motion of the spatula blade stirs and tosses the food and liquid ingredients from all sides of the wok. Further details of the cam are as follows. The cam is operably mounted perpendicularly to the end of the cam rod. The cam rod is rotatably mounted operably to the cam rod support means. The cam rod is operably attached to the third driving means. The third driving means is operably coupled to the third motor means. The third driving means transmits a counterclockwise rotary motion of the third motor means to clockwise rotary motion of the cam. The motion of the cam is synchronized with the motion of the spatula arm since both the cam and the spatula arm are driven by the same third motor means. The third motor means is activated and deactivated by signals from the computer control system.

The liquid dispensing component illustrated in FIG. 4, is comprised of a plurality of identical liquid dispensers each comprised of a bulk container 1 to hold the liquid, a length of hose 2 operably attached to an outlet means on each bulk container, a pinch valve 3 installed on each length of hose so that the flow of liquid is controlled by the pinch valve; a horizontal rack to support the pinch valves 4, a funnel means 6, a third base 5 to support the horizontal rack and the funnel means, and a fourth base 7 to support the bulk containers. The individual pinch valves are electrically activated (to open) and deactivated (to close) by signals from the computer control system. The pinch valves are operably mounted on the horizontal rack which is operably mounted on the third base. The discharging ends of the hoses converge into the funnel means. The funnel means is mounted on the third base with the spout of the funnel means pointing into the wok. The bulk containers, holding liquid ingredients such as soy sauce, chicken broth, cooking oil and the like, are mounted on the fourth base which is operably attached to the back of the Chinese stove.

When a pinch valve is activated, gravity feed produces a flow of the respective liquid which passes downward through the respective hose through the funnel means and into the wok. The length of time a pinch valve is opened is calculated by the computer control system to dispense a desired quantity of the respective liquid. Through extensive experimentation mathematical equations for flow rates for each liquid have been derived and programmed into the computer control system. These equations allow a recipe specification of one teaspoon of soy sauce, for example, to be converted to a time interval for which the respective pinch valve is to remain open in order to dispense one teaspoon of soy sauce. These equations are shown in lines 4070-4130 of the computer program listing which is subsequently presented. Although gravity feed is employed in this applicant's prototype, it is apparent that pressurization of the liquid containers could be used to increase the flow rates. It is also apparent that food-grade micropumps and corresponding control means could be substituted for the pinch valves to meter precise quantities of the various liquids.

The temperature measuring component, illustrated in FIG. 5, is comprised of a temperature sensor 43 for sensing the temperature of the wok, a digital thermometer 44 with BCD output for converting electrical signals from the temperature sensor to temperature measurements for input to the computer control system, a thermocouple protection tube 45, a sensor support means 46 for supporting the temperature sensor and thermocouple protection tube, and a fifth base 47 for supporting the sensor support means. The thermocouple protection tube is positioned inside the vertical pipe 12. The temperature sensor fits inside the thermocouple protection tube thereby insulating the temperature sensor from the vertical pipe in the region around the intense heat of the gas burner. The temperature sensor and the thermocouple protection tube are operably attached to the sensor support means. The tip of the temperature sensor extends upward through the thermocouple protection tube to touch the bottom surface of the wok. Electrical leads of the temperature sensor extend downward through the thermocouple protection tube and into the sensor support means. The electrical leads emerge from the sensor support means and travel beneath the Chinese stove to the digital thermometer located near the computer control system. The sensor support means fits into a hole in the fifth base. A spring means 42 in the hole of the fifth base biases the sensor support means upwardly thereby biasing the tip of the temperature sensor against the bottom of the wok.

The gas valve component is comprised of a gas valve 48 of FIG. 1, electrically operated, operably installed in the gas burner supply line of the Chinese stove downstream of the supply branch to the pilot light. The gas valve is activated (to open) and deactivated (to close) by signals from the computer control system. In the deactivated position only the pilot light is on. In the activated position a full flow of gas is supplied to the gas burner from the supply source. As a matter of safety, when the computer control system activates the gas valve the computer control system checks for an immediate increase in temperature of the wok. If this temperature increase does not occur within a few seconds the computer control system deactivates the gas valve and displays a message to the operator to check the pilot light.

The computer control system component is comprised of a general purpose digital microcomputer system 50 with a minimum of 16000 bytes of memory, a programming language BASIC, a video display monitor, a data storage means, a data entry keyboard, an electronic interface 49 which by computer generated signals activates and deactivates the means to rotate the wok, the means to drive the spatula, the means to rotate the rotatable divider of the food tray, activates and deactivates the plurality of liquid dispensers, activates and deactivates the gas valve, and receives the temperature measurements from the digital thermometer. A schematic diagram of the electronic interface is shown in FIG. 9. The numbers with slashes on the lines connecting the components in the diagram indicate the number of wires connecting those components. When no number is given one wire may be assumed.

Activation and deactivation of the respective first, second and third motor means, the gas valve and the plurality of pinch valves is achieved by a program instruction in BASIC: "OUT, port, value". This instruction outputs a byte value to a specified computer port and generates a write command. The byte value contains an address of the device to be selected and a bit pattern which indicates whether the device is to be activated or deactivated. When the computer control system interface receives a write command and a valid address from the computer, it decodes the address and routes the 5 low-order bits on the computer data bus to the device decode and select logic. The device decode and select logic decodes the 5 low-order bits and activates or deactivates the selected device. Temperature measurements of the wok are input to the computer control system by a program instruction in BASIC: "INP, port". This instruction inputs a byte value from the specified computer port and generates a read command. Four of these instructions are utilized under program instructions to input a temperature measurement. The first and second INP instructions input a status indicator from the digital thermometer. When the status indicator shows that the temperature measurement is latched on the computer data bus, the third and fourth INP instructions input the low and high order bits of the 15 bit temperature measurement. When the computer control system interface receives a read command and a valid address from the computer, it decodes the address and then reads the temperature status or the temperature measurement respectively from the digital thermometer.

The computer control system is further comprised of program instructions to store and process recipe data, to display a menu to the operator, to accept a selection from the menu, and to activate and deactivate the above components to cook the menu selection. The computer control system interface is constructed using conventional techniques for digital circuit logic and commercially available components. A program structure flowchart is shown in FIGS. 7 and 8. The number in the upper right corner of each box refers to the beginning line number in the computer program for the respective subroutine. Following is the source listing of the entire computer program according to this invention. ##SPC1##

In the utilization and operation of this invention, the bulk containers are filled with one cup to several quarts, depending on the expected number of orders to be prepared, of soy sauce, chicken broth, cooking oil, sherry, liquid corn starch, oyster sauce, sesame oil, etc. In a priming step performed once each day, each normally deactivated pinch valve is briefly activated to allow the respective liquid to flow into the respective hose forcing out the air in the hose between the bulk container and the pinch valve. To do this the operator, prompted by a meassage on the video display monitor, presses a key on the computer keyboard. Next, the operator, prompted by a message on the video display monitor, enters the ambient temperature of the cooking oil. This data is used by the computer control system in calculating the flow rate for the cooking oil since the flow rate is temperature dependent. At the completion of these steps, a menu is presented to the operator on the video display monitor. When an order is to be cooked, the operator selects a corresponding food tray marked with the name of the menu selection ordered and containing the precut food ingredients for that recipe. The operator mounts the food tray on the tray spindle, types the number of the menu selection on the computer keyboard, visually confirms the name of the recipe which is displayed and presses the Y key on the keyboard to start the automatic cooking. The operator is now free to initiate another order on another device of this invention. The computer control system activates the normally deactivated gas valve, igniting the gas burner and heating the wok. Temperature measurements of the wok are continually read from the digital thermometer by the computer control system. When the gas burner has heated the wok to the cooking temperature specified in the recipe the computer control system activates the normally deactivated first motor means which initiates rotation of the wok. The computer control system then activates the corresponding pinch valve to dispense cooking oil in the quantity specified for this recipe. Next, the computer control system activates the normally deactivated third motor means which initiates the stirring action of the spatula. After a few seconds, to allow the cooking oil to heat, the computer control system activates the normally deactivated second motor means to rotate the rotatable divider of the food tray to add the first food ingredient and then deactivates the second motor means. At subsequent precisely timed intervals, specified by the recipe, the computer control system rotates the rotatable divider of the food tray as above to add additional food ingredients. Additionally, the computer control system activates appropriate pinch valves to add liquid ingredients at precisely time intervals and in the precise quantities as specified in the recipe. Throughout the cooking process temperature measurements are checked approximately once every one and a half seconds to insure the proper cooking temperature is being maintained. If the temperature should rise too high, that is, if it reaches the upper limit of an allowable range, the computer control system deactivates the gas valve until the temperature drops to the lower limit of the allowable range, at which time the computer control system again activates the gas valve to turn on the gas burner. The allowable temperature range is plus or minus 3% of the temperature specified in the recipe. For example, a cooking temperature of 350.degree. F. has an allowable range of 340.degree. F. to 360.degree. F. At the completion of the specified cooking time, the computer control system deactivates the first and third motor means which stops the wok rotation and the stirring action of the spatula, and deactivates the gas valve which turns off the gas burner. This signals the operator that the food is done at which time the operator scoops the food onto a dish for serving. The operator then removes the spatula and the wok and replaces them with a clean spatula and wok. The menu is automatically redisplayed on the video display monitor and the apparatus is ready to cook the next order. Although the computer program of this applicant's prototype employs a technique of counting computer cycles of known duration to determine the number of elapsed seconds for timing purposes, it is apparent that a real time clock with appropriate interface means to the computer control system could be used for precise timing control.

The method and apparatus of this invention has extreme versatility for cooking virtually any stir-fry recipe from virtually any Chinese school of cooking. Any desired food ingredients or combination of food ingredients can be added in any chosen sequence at any chosen time interval in the cooking process. Likewise, any liquid ingredient or combination of liquid ingredients can be precisely measured and added in any chosen sequence at any chosen time intervals. Furthermore, the cooking temperature can be repeatedly changed during the cooking process at any chosen time interval. The program instructions of the computer control system are designed to allow easy entry and modification of recipes. The number of recipes that can be stored is limited only by the amount of computer memory available. It is anticipated that a restaurant user of this invention might utilize anywhere from a dozen recipes to 300 or more.

To enter a new recipe the person preparing the recipe first writes the recipe on a recipe worksheet. A sample filled out recipe worksheet is shown in FIG. 6. Using the abbreviations shown at the bottom of the recipe worksheet the person lists the name of the recipe, the initial cooking temperature and then lists the food and liquid ingredients of the recipe in the sequence in which they are to be added. For each food ingredient, the person lists the cooking time desired prior to adding the next ingredient. For each liquid ingredient the person lists the quantity of the liquid ingredient to be added and the desired cooking time prior to adding the next ingredient. The person also lists any changes in cooking temperature desired for the recipe in the sequence desired. This is the essential recipe information that would be described in any Chinese cookbook.

The recipe information is then keyed from the recipe worksheet into the computer program by the person preparing the recipe. Each line is entered as a DATA statement beginning with the next available line number. For example, in the program listing, DATA statements containing recipe information occupy lines 1 to 625. Therefore, a new recipe could be entered beginning at line 626. When all recipe changes or additions have been entered, the person also updates line 1 containing the total number of recipes. If line 1 previously showed "75" recipes and 4 new recipes were entered, this line would be changed to "79". New or revised recipes are permanently stored for immediate or later use.

The components of this invention taken individually are not considered to be the particular novel portion of this invention. The novelty is believed to reside in the combined use of the components to achieve a result not anticipated by the prior art, namely, the ability of an unskilled operator to cook superior Chinese stir-fry food, and to do so with higher productivity and with a larger repetoire of multiregional recipes than the skilled traditional Chinese chef.