WO2022075927A1

WO2022075927A1 - Control method for an oven

Info

Publication number: WO2022075927A1
Application number: PCT/TR2020/050919
Authority: WO
Inventors: Fatih ZUNGOR; Burhaneddin EMRE; Gozde AKPAK; Buse SEVIM
Original assignee: Mamur Teknoloji Sistemleri San. A.S.
Priority date: 2020-10-06
Filing date: 2020-10-06
Publication date: 2022-04-14
Also published as: EP4226090A1

Abstract

The invention relates to an oven control method comprising the process steps of measurement of a current temperature (Ta) of the inner chamber (8) during the cooking operation by a temperature sensor (26) disposed in the muffle (10), and generating a door open signal in the open position of the door (7) when the control unit (20) detects that the current temperature (tç) falls below the minimum temperature (Tmin) during a current cycle time (Ta) shorter than the previous recorded cycle time (tö) that is read from an associated memory module in a signal transmission manner.

Description

CONTROL METHOD FOR AN OVEN

TECHNICAL FIELD

The invention relates to an oven operation control method and an oven control method and device for detecting the opening and closing of the oven door, especially during cooking.

STATE OF THE ART

During the operation of the oven, the opening of the muffle surrounding a cooking chamber of the oven is covered by a door hinged to a housing. During the cooking, the user can intervene in the process by opening the door before the cooking is completed for various reasons. During the cooking process, information regarding the status of the door (open or closed) is provided to the control device for safety issues or time calculation, etc. In order to achieve this, the door is equipped with a mechanical switch, magnetic sensor, optical sensor and an open or closed signal is fed to the control unit.

EP1394472B1 discloses the operation method of a cooking appliance. There is a second time period following to the first time period. In this control range, the cooking temperature is again set to the point where a second control interval. When the cooking chamber door is opened during the second time period, the cooking chamber temperature time curve makes a descent angle greater than the registered descent angle of the control device as the temperature of the chamber decreases. The control means cuts the period prematurely before its current end. Thus, the controller makes a readjustment to the switches.

BRIEF DESCRIPTION OF THE INVENTION

The object of the invention is to provide a simple detection of the open or closed status of the oven door during the cooking process.

In order to achieve the aforementioned object, the present invention relates to an oven control method comprising the process step of switching on and off a heating element driven by a control unit provided in the housing, creating cascading cycles between a minimum control temperature and a maximum control temperature that define a temperature band to provide a predetermined reference temperature value in the cooking chamber in a cooking operation in an housing that delimits a cooking chamber and comprises a heat-insulating muffle with at least one heating element and a door hinged to the housing to openly cover the intake of the muffle, with the door in the closed position. The control method further comprises the process step of measurement of a current temperature of the inner chamber during the cooking operation by a temperature sensor located in the muffle and generating a door open signal in the open position of the door when the control unit detects that the current temperature falls below the minimum temperature during a current cycle time shorter than the previous recorded cycle time that is read from an associated memory module in a signal transmission manner. The current temperature drops below the minimum temperature sooner than the previous cycle time, allowing the the control unit to detect that the door is opened without the need for additional equipment. The door open signal can initiate a predetermined algorithm in the control unit or can only be stored in the memory module as data to be used for a later operation.

A preferred embodiment of the invention comprises the process step of activating the heating element continuously during an initial heating period until it reaches the temperature band of the inner chamber when the cooking operation starts. In this case, it is possible for the inner chamber limited by the cavity to reach the reference temperature as soon as possible. Thus, preheating is completed in a short time when the cooking operation in the oven is started.

A preferred embodiment of the invention comprises the process steps of activating and deactivating the heating element for a sample cycle such that the reference temperature in the inner chamber is maintained in a learning phase, and comparison of the sample cycle time with the subsequent cycle time by the control unit and saving the sample cycle time as the previous cycle time in the memory module if both time periods are equal to one another within a predetermined tolerance. In this case, the current cycle time to be referred by the control unit when generating the door open signal is reliably obtained by sampling.

A preferred embodiment of the invention comprises the process step of comparing the previous cycle time with any preceding sample cycle time and preserving the previous cycle time in the memory module if both time periods are equal to one another within a predetermined tolerance. In one possible embodiment, the control unit is capable of performing sample cycle time verification by sequentially comparing two preceding cycle times to determine the sample cycle time with full accuracy. Thus, the door open signal can be obtained with great precision, even in cases where the current cycle time is slightly different in percentage from the sample cycle time. A preferred embodiment of the invention comprises the process step of saving the door open status information to the memory module by the control unit in case of detecting such signal, measuring the current temperature if there is a door open signal and generating a door close signal if the maximum control temperature is exceeded. This makes it possible to obtain not only the door open signal, but also the close signal with the same simple device. A preferred embodiment of the invention comprises the process step of recording the door close status information in the memory unit when the door close signal is generated by the control unit. The door close signal can start a predetermined algorithm in the control unit or can only be stored in the memory module as data to be used for a later operation. In a possible embodiment of the invention, the control unit can calculate the time difference between the door open and close signals and activate a heat compensation algorithm accordingly. In one possible embodiment of the invention, the door close signal may end the countdown when an alarm algorithm counts down to a predetermined time by activating the door open signal.

In a preferred embodiment of the invention, the minimum control temperature and the maximum control temperature are provided constant during the current cycle in accordance with the reference temperature. Therefore, the bandwidth for the sample cycle can be simply calculated by the control unit by simply determining the maximum and minimum temperatures, respectively, as 5% above and below the current temperature.

A preferred embodiment of the invention comprises the process step of activating an alarm unit in case a door open signal is detected by a controller of the control unit for a predetermined period of time. In this case, the alarm unit can warn the user with a sound, image, remotely accessible signal or tactile feedback against prolonged door open status, which will increase the loss of efficiency during the cooking operation.

In a preferred embodiment of the invention, the control unit is equipped with a mechanical thermostat driving the heating element and comprises the process step of adjusting the mechanical thermostat to the reference temperature with a control element outside the housing before the cooking operation. The mechanical thermostat can simply drive the temperature element between the maximum and minimum temperatures for a set reference temperature with a predetermined bandwidth.

A preferred embodiment of the invention comprises an oven with an oven control device that performs any of the above-mentioned control methods. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is the front schematic illustration of an oven with a mechanical thermostat where a representative application of the oven control method of the invention is carried out.

Figure 2 is a temperature/time diagram obtained with the oven control method according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

In this detailed explanation, the subject development of the invention is explained without any limitation and only with reference to examples for a better understanding of the subject.

In Figure 1 , a representative embodiment of a household oven is shown schematically from the front portion. The oven delimits a cooking chamber (8) with a heat-insulated muffle (10) located in an housing (1 ). A heating element (5) and an auxiliary heating element (6) are located in the electrical resistance structure adjacent to the upper and lower walls of the muffle (10), respectively. In the outer portion of the housing (1 ), a door (7) is hinged to the housing (1 ) in such a way that it can be opened, covering the open intake of the muffle (10) from one side. The door (7) is in the form of a panel and there is a panel on the upper portion, on which the rotating control elements (2) are located. A control unit (20) is located on the rear portion of the panel, comprising a mechanical switch (27) that is adjustable to the control element (2). The heating element (5) in the electrical resistance structure is driven by opening and closing the mechanical thermostat (28). On the control unit (20), there is a controller (22) in the integrated circuit structure and a memory module (24) mounted on the same circuit board and connected to provide signal transmission. Furthermore, the control unit (20) is connected to an alarm unit (27) in such a way as to provide signal transmission. A temperature sensor (26) is mounted on the back wall of the muffle (10) in such a way that it detects the temperature of the cooking chamber (8). An electrical cable connects the temperature sensor (26) to the controller (22) of the control unit (20), which is the electronic central processor, providing signal transmission thereof. For the cooking operation, a food (3) is placed on a tray (4) and the door (7) is opened and the tray (4) is inserted into the muffle (10). By rotating the control element (2), the cooking chamber (8) is adjusted to a reference temperature (T _ref ) at which the cooking operation will be performed. The temperature increase in the cooking chamber (8) is initiated in the closed position of the door (7) by transferring the electricity from the mains to the heating element (5) via the mechanical thermostat (28).

In Figure 2, the cooking program is provided as a temperature-time diagram. The cooking operation starts with the mechanical switch (28) energizing the heating element (5). Meanwhile, the mechanical thermostat (28) keeps the heating element (5) continuously operating for an initial heating period (ti) for the temperature of the cooking chamber (8) to reach the reference temperature (T_ret) set by the control element (2) as quickly as possible. Meanwhile, the temperature in the cooking chamber (8) closely exceeds the reference temperature (T_ref). The mechanical thermostat (28) cuts the energy of the heating element (5 ) at the end of the first heating period (t 1 ) and starts the cooking cycle. The temperature sensor (26) provides a valid temperature (T_a) information to the control unit (20) by continuously controlling the temperature of the cooking chamber (8) from the beginning of the cooking process. The memory module (24) contains values for a minimum control temperature (T_min) than the reference temperature (T_ret) and a large maximum control temperature (T_max) corresponding to the reference temperature (T_ret) selected as a tabular value and forming a temperature band (B) gap thereof. The mechanical thermostat (28) maintains the temperature of the cooking chamber (8) by driving the heating element (5) in its open-closed structure, making small fluctuations as per the set reference temperature (T_ref). After the first heating period (ti), a cycle is completed by turning off the heating element (5) at peak value above the reference temperature (T_ret) of this fluctuation during a sample cycle period (ts) and re-energizing it at a low value below the reference temperature (T_ref). Following this, the last cycle before the door (7) opens repeats the temperature cycle of the sample cycle time (t 2 ) described during the previous cycle time (t₀). When the door (7) is opened during the cooking process, a sudden temperature loss occurs by breaking the repeated temperature cycle during the previous cycle time (t₀). In this case, the cooking chamber (8) temperature drops below the minimum control temperature (T_min) value retained in the memory module (24) for the reference temperature (T_ref). In case of falling below the minimum control temperature (T_min) received from the temperature sensor (26) that constantly monitors the cooking chamber (8), the controller (22) first checks for a current cycle time (t₅) and detects that it is less than the previous cycle time (t₀), and generates the door open signal and stores the door open information in the memory module (24) thereof. At the same time, the controller (22) starts a counter and checks by running an algorithm whether the door (7) remains open for a critical period while the cooking operation continues and the heating element (5) is activated. According to this algorithm, the door close information is controlled from the memory module (24), and if this value is negative, it is ensured that the controller (22) activates the alarm unit (27), which is an audio circuit, until a predetermined time, for example 30 seconds. Thus, the user is informed that the door (7) is open, posing a danger and negatively affecting the efficiency during the cooking operation. After the door (7) is closed, the temperature of the cooking chamber (8) rises rapidly, as the heating element (5) is constantly on during the door open state. In this case, when the maximum control temperature (T_max) is exceeded, the door (7) generates a door close signal by comparing the maximum control temperature (T_max) that the controller (22) reads from the memory module (24) relative to the reference temperature (T_ret) with the current temperature (T_a) read by the temperature sensor (26). A secondary control algorithm is the controller's (22) confirmation of the fact that the long cycle time (tu) following the valid cycle time (tg) is greater than the valid cycle time (tg). In this way, the running alarm algorithm is ceased and the cycle continues as before the door (7) is opened. The controller (22), as the processor, compares the previous cycle time (to) with the previous cycle time during the cycle period when the door (7) is not yet opened. Therefore, three cycle times in succession from the previous cycle time (to) are coded to the memory module (24) and compared with each other, and if the time values are close within the measurement tolerance, the previous cycle time (to) value is retained in the memory module (24) in the door open position as a reference against comparison with the current cycle time (t₅) without updating.

REFERENCE NUMBERS

1 Housing 27 Alarm unit

2 Control element 28 Mechanical thermostat

3 Food T _min Minimum control temperature

4 Tray T max Maximum control temperature

5 Heating element T ref Reference temperature

6 Auxiliary heating element T _a Current temperature

7 Door 1 1 Initial heating time

8 Cooking chamber 1 2 Sample cycle time

10 Muffle t o Previous cycle time

20 Control unit 1 ₅ Valid cycle time

22 Controller t _u Long cycle time

24 Memory module B Temperature band

26 Temperature sensor

Claims

7

CLAIMS - An oven control method comprising the process step of switching on and off a heating element (5) driven by a control unit (20) provided in the housing (1 ), creating cascading cycles between a minimum control temperature (T_min) and a maximum control temperature (T_max) that define a temperature band to provide a predetermined reference temperature (T_ret) value in the cooking chamber (8) in a cooking operation in an housing that delimits a cooking chamber (8) and comprises a heat-insulating muffle (10) with at least one heating element (5) and a door (7) hinged to the housing (1 ) to cover the opening of the muffle (10), with the door (7) in the closed position, characterized by further comprising the process step of measurement of a current temperature (T_a) of the inner chamber (8) during the cooking operation by a temperature sensor (26) located in the muffle (10) and generating a door open signal in the open position of the door (7) when the control unit (20) detects that the current temperature (t₅) falls below the minimum temperature (T_min) during a current cycle time (T_a) shorter than the previous recorded cycle time (t₀) that is read from an associated memory module in a signal transmission manner. - A control method according to Claim 1 , wherein the method comprising the process step of activating the heating element (5) uninterruptedly during a first heating period (ti) until it reaches the temperature band (B) of the inner chamber when the cooking operation starts. - A control method according to any one of the preceding claims, wherein the method comprising the process steps of activating and deactivating the heating element (5) for a sample cycle (ts)such that the reference temperature (T_ret) in the inner chamber is maintained in a learning phase, and comparison of the sample cycle time (ts) with the subsequent cycle time (ts) by the control unit and saving the sample cycle time (ts) as the previous cycle time (t₀) in the memory module if both time periods are equal to one another within a predetermined tolerance. - A control method according to Claim 3, wherein the method comprising the process step of comparing the previous cycle time (t₀) with any preceding sample cycle time (ts) and preserving the previous cycle time (t₀) in the memory module if both time periods are equal to one another within a predetermined tolerance. - A control method according to any of the preceding claims, wherein the method comprising process step of saving the door open status information to the memory 8 module (24) by the control unit (20) in case of detecting such signal, measuring the current temperature (T_a) if there is a door open signal and generating a door close signal if the maximum control temperature (T_max) is exceeded.

6- A control method according to Claim 5, wherein the method comprising the process step of recording the door close status information in the memory module (24) when the door close signal is generated by the control unit (20).

7- A control method according to any one of the preceding claims, wherein the minimum control temperature (T_min) and the maximum control temperature (T_max) are provided constant during the current cycle time (t₅) as per the reference temperature (T_ref).

8- A control method according to any one of the preceding claims, wherein the method comprising the process step of activating an alarm unit (9) in case a controller (22) of the control unit (20) detects a door open signal for a predetermined period of time.

9- A control method according to any of the preceding claims, wherein the control unit (20) is equipped with a mechanical thermostat (28) driving the heating element (5) and comprises the process step of adjusting the mechanical thermostat (26) to the reference temperature (T_ret) with a control element (2) outside the housing (1 ) before the cooking operation.

10- An oven with an oven control device performing a control method according to any preceding claim.