EP2798272A1

EP2798272A1 - Oven with infrared sensor

Info

Publication number: EP2798272A1
Application number: EP12808270.8A
Authority: EP
Inventors: Ahmet Ferit Cosan
Original assignee: Arcelik AS
Current assignee: Arcelik AS
Priority date: 2011-12-26
Filing date: 2012-11-26
Publication date: 2014-11-05
Anticipated expiration: 2032-11-26
Also published as: WO2013098003A1; EP2798272B1

Abstract

The present invention relates to an oven (1) comprising an exterior body (2), a cooking cavity (3) wherein the cooking process is performed, a control unit (4), a door (5), an outer panel (6) forming the outer surface of the door (5) facing the user and produced from glass, an inner panel (7) having an air gap between the outer panel (6) and itself, forming the inner surface of the door (5) facing the cooking cavity (3), a front panel (8) located at the upper side of the door (5) and that protects the control unit (4), a fan (10) and an infrared sensor (13) that detects the infrared rays emitted from the foodstuff being cooked in the cooking cavity (3) to determine the outer surface temperature thereof and that has a converging lens (11) and a thermopile array (12). An opening is located at the upper side of the door and the infrared sensor is placed to the front panel with its lens facing the opening.

Description

OVEN WITH INFRARED SENSOR

The present invention relates to an oven comprising an infrared sensor detecting infrared rays emitted from the foodstuff being cooked.
In the state of the art, infrared temperature sensors that provide the surface temperature to be detected without contacting the foodstuff being cooked are used in ovens. The infrared temperature sensor detects the infrared rays emitted from the foodstuff being cooked and determines the temperature, and the control unit regulates the cooking process parameters according to the data received from the infrared temperature sensor. The infrared temperature sensor is composed of a lens converging (focusing) infrared rays emitted from the foodstuff being cooked and a thermopile array that converts the temperature data received by means of the converged infrared rays to electrical voltage and transmits it to the control unit. Since the infrared temperature sensors detect the infrared rays emitted from the heating materials, no obstruct must be between them and the foodstuffs the surface temperature of which is desired to be measured, and the foodstuff being cooked must be in the field of view of the infrared temperature sensor. The most suitable position that comes to mind for measuring the surface temperature of the foodstuff being cooked in any position in the oven is the top wall of the cooking cavity. By being placed into a window opened for example in the top wall of the cooking cavity, the infrared temperature sensor can easily see the foodstuff; however, the temperature of the cooking cavity may reach 280 degrees in known programs and 500 degrees in pyrolytic ovens. It is not possible for an infrared temperature sensor disposed at the top wall of the oven to endure such high temperatures. One possible solution for protection against high temperatures is to place a glass material that both provides heat insulation and conducts infrared rays between the infrared temperature sensor and the cooking cavity; however, cost of such a material is very high.
In the Japanese Patent No. JP2721827, a temperature estimating unit is described, comprising an infrared temperature sensor, providing the foodstuffs to be cooked at the desired temperature.
In the United States Patent No. US6158329, a cooking device is described, comprising a sensor module that is placed into the ventilating duct connected to the cooking chamber and that measures the infrared radiation in the cooking chamber.
In the Japanese Patent No. JP3829274, a microwave oven is described, comprising an infrared sensor that measures the surface temperature of the foodstuffs being cooked.
In the Japanese Patent No. JP3812346, a cooking device is described, comprising an infrared sensor that sees the foodstuff through a hole arranged at the ceiling of the cooking chamber.
The aim of the present invention is the realization of an oven comprising an infrared sensor that is not affected by the high temperatures in the cooking cavity.
The door of the oven realized in order to attain the aim of the present invention, explicated in the first claim and the respective claims thereof is composed of an outer panel forming the outer surface thereof and produced from glass, and an inner panel located at the inner side thereof and produced from glass. An opening is arranged at the upper side of the door and an infrared sensor facing the opening is placed to the front panel. The infrared sensor detects the infrared rays that are emitted from the foodstuff in the cooking cavity to reach the door and that pass through the opening by reflecting from between the outer panel and the inner panel, and provides the surface temperature of the foodstuff being cooked to be determined.
The infrared sensor is placed into the front panel at the upper side of the door, in alignment with the door and the part of the infrared sensor where the thermopile array is located remains inside the front panel. The end of the infrared sensor where the lens converging the rays is located extends from the lower surface of the front panel towards the opening in the vertical direction.
In an embodiment of the present invention, the infrared sensor is placed inside the front panel in the vicinity of the control unit and the present cooling system provides both the control unit and the infrared sensor to be cooled. Moreover, the length of the cables providing communication between the infrared sensor and the control unit are kept short, thus providing ease of connection and immunity against electromagnetic interferences.
In another embodiment of the present invention, a hole is arranged on the inner panel, that provides the infrared rays emitted from the cooking cavity to be transmitted into the door.
In another embodiment of the present invention, a reflector that is flat, concave or convex is placed between the outer panel and the inner panel of the door, the infrared rays emitted from the cooking cavity are provided to be effectively reflected towards the opening from the inside of the door.
In another embodiment of the present invention, the motor of the cooling fan can be operated at variable speed; the control unit decides that the amount of humidity increases in the steady state where the temperature stops increasing and the temperature oscillates around a constant value by monitoring the temperature data received from the infrared sensor, thus increases the fan speed and the problem of vapor particles sticking to the lens of the infrared sensor and blocking its view is eliminated.
In the oven of the present invention, being placed into the control panel, the infrared sensor is not subjected to high temperatures and is cooled by the fan together with the control unit.
The oven realized in order to attain the aim of the present invention is illustrated in the attached figures, where:
Figure 1 - is the schematic view of an oven.
The elements illustrated in the figures are numbered as follows:

Oven
Exterior body
Cooking cavity
Control unit
Door
Outer panel
Inner panel
Front panel
Ventilating duct
Fan
Lens
Thermopile array
Infrared sensor
Opening
Hole
Reflector

The oven (1) comprises an exterior body (2), a cooking cavity (3) wherein the cooking process is performed, a control unit (4) that regulates the cooking process parameters, a door (5) providing access into the cooking cavity (3), an outer panel (6) forming the outer surface of the door (5) facing the user and produced from glass, an inner panel (7) having an air gap between the outer panel (6) and itself, forming the inner surface of the door (5) facing the cooking cavity (3) and produced from glass, a front panel (8) located at the upper side of the door (5) and that protects the control unit (4), a ventilating duct (9) located above the cooking cavity (3), a fan (10) placed into the ventilating duct (9), sucks air through the ventilating holes on the exterior body (2), discharging it from the ventilating duct (9), thus providing the cooling of the control unit (4) and the discharging of the humid air and an infrared sensor (13) that detects the infrared rays (shown in the figure with dashed lines) emitted from the foodstuff being cooked in the cooking cavity (3) to determine the surface temperature thereof and that has a converging lens (11) that converges the infrared rays to a single point and a thermopile array (12) that converts the radiation data received into electrical voltage.
The oven (1) of the present invention comprises an opening (14) located at the upper side of the door (5) and between the outer panel (6) and the inner panel (7) and the infrared sensor (13) that is placed to the front panel (8), with its lens (11) facing the opening (14) and that detects the infrared rays reflected from between the outer panel (6) and the inner panel (7) and passing through the opening (14).
The infrared sensor (13) is placed to the front panel (8) in alignment with the door (5). The part of the infrared sensor (13) where the thermopile array (12) is located remains inside the front panel (8). The end of the infrared sensor (13) where the lens (11) thereof is located extends from the lower surface of the front panel (8) towards the opening (14) in the vertical direction so that the opening (14) remains in the field of view. The infrared sensor (13) placed to the front panel (8) is not affected by the high temperatures in the cooking cavity (3).
During the cooking process, the infrared rays emitted from the foodstuff and reaching the door (5) are reflected from between the outer panel (6) and the inner panel (7), pass through the opening (14) and are detected by the infrared sensor (13). The thermopile array (12) converts the infrared radiation data to electrical voltage and transmits it to the control unit (4). The control unit (4) determines the temperature of the foodstuff being cooked by evaluating the voltage signals received from the thermopile array (12) and regulates the cooking process parameters.
In an embodiment of the present invention, the infrared sensor (13) is placed into the front panel (8) near the control unit (4). Thus, the infrared sensor (13) is cooled by the fan (10) together with the electronic elements present in the control unit (4) and the front panel (8). Moreover, the length of the cables between the infrared sensor (13) and the control unit (4) shortens, thus providing ease of connection.
In an embodiment of the present invention, the oven (1) comprises a hole (15) that is arranged on the inner panel (7) and that transmits the infrared rays emitted from the foodstuff being cooked into the door (5), between the outer panel (6) and the inner panel (7). During the cooking process, the infrared rays emitted from the foodstuff enter between the outer panel (6) and the inner panel (7) from the hole (15), reach the opening (14) and are detected by the infrared sensor (13).
In another embodiment of the present invention, the oven (1) comprises a reflector (16) that is located between the outer panel (6) and the inner panel (7) and that reflects the infrared rays entering through the hole (15) to the opening (14).
In a version of this embodiment, the surface of the reflector (16) that reflects the infrared rays entering through the hole (15) to the opening (14) is concave.
In a version of this embodiment, the surface of the reflector (16) that reflects the infrared rays entering through the hole (15) to the opening (14) is convex.
In another embodiment of the present invention, the motor driving the fan (10) is of variable-speed type, and the control unit (4) decides that the amount of humidity increases in the cooking cavity (3) in the steady state where the temperature stops increasing and the temperature oscillates around a constant value by monitoring the temperature data received from the infrared sensor (13) and thus increases the fan (10) speed until the end of the cooking process. Thus, the moisture increasing in the cooking cavity (3) is provided to be quickly discharged to the outer environment, the vapor particles in the humid air are prevented from sticking to the lens (11) of the infrared sensor (13) close to the ventilating duct (9) and the infrared sensor (13) is prevented from making inaccurate measurements.
In the oven (1) of the present invention, the infrared sensor (13) detects the temperature of the foodstuff in the cooking cavity (3) without being subjected to high temperatures. By placing the infrared sensor (13) to the front panel (8) at the position close to the control unit (4), the length of the cables needed for communicating with the control unit (4) are kept at minimum and immunity against electromagnetic interferences is provided. Moreover, the infrared sensor (13) in the front panel (8) benefits from the cooling provided by the fan (10) for the control unit (4).
It is to be understood that the present invention is not limited by the embodiments disclosed above and a person skilled in the art can easily introduce different embodiments. These should be considered within the scope of the protection disclosed by the claims of the present invention.

Claims

An oven (1) comprising an exterior body (2), a cooking cavity (3) wherein the cooking process is performed, a control unit (4), a door (5), an outer panel (6) forming the outer surface of the door (5) facing the user, an inner panel (7) having an air gap between the outer panel (6) and itself, forming the inner surface of the door (5) facing the cooking cavity (3), a front panel (8) located at the upper side of the door (5) and that protects the control unit (4), a fan (10) and an infrared sensor (13) that detects the infrared rays emitted from the foodstuff being cooked in the cooking cavity (3) to determine the surface temperature thereof and that has a converging lens (11) and a thermopile array (12), characterized in that an opening (14) located at the upper side of the door (5) and between the outer panel (6) and the inner panel (7) and the infrared sensor (13) that is placed to the front panel (8), with its lens (11) facing the opening (14) and that detects the infrared rays emitted from the foodstuff being cooked and reflected from between the outer panel (6) and the inner panel (7) and passing through the opening (14).
An oven (1) as in Claim 1, characterized in that the infrared sensor (13) placed to the front panel (8) in alignment with the door (5), of which the part where the thermopile array (12) is located remains inside the front panel (8) and of which the end where the lens (11) thereof is located extends from the lower surface of the front panel (8) towards the opening (14) in the vertical direction so that the opening (14) remains in the field of view of the lens (11).
An oven (1) as in Claim 1 or 2, characterized in that the infrared sensor (13) that is placed into the front panel (8) near the control unit (4).
An oven (1) as in any one of the above claims, characterized in that a hole (15) that is arranged on the inner panel (7) and that transmits the infrared rays emitted from the foodstuff being cooked into the door (5).
An oven (1) as in Claim 4, characterized in that a reflector (16) that is located between the outer panel (6) and the inner panel (7) and that reflects the infrared rays entering through the hole (15) to the opening (14).
An oven (1) as in Claim 5, characterized in that a reflector (16), of which the surface reflecting the infrared rays entering through the hole (15) to the opening (14) is concave.
An oven (1) as in Claim 5, characterized in that a reflector (16), of which the surface reflecting the infrared rays entering through the hole (15) to the opening (14) is convex.
An oven (1) as in any one of the above claims, characterized in that the control unit (4) that decides that the amount of humidity increases in the cooking cavity (3) in the steady state where the temperature stops increasing and the temperature oscillates around a constant value by monitoring the temperature data received from the infrared sensor (13) and thus increases the fan (10) speed until the end of the cooking process.