Hot air cooking appliance with a speed-controlled motor

Abstract

The present invention relates to a hot air cooking apparatus, in particular of the type hot air fryer comprising: a cooking chamber intended to receive food to be cooked or heated, a heating element (8) arranged to produce heat, an air circulation device comprising a fan (12) and a motor (13) arranged to drive the fan (12), and arranged to generate an airflow coming into contact with the heating element (8) so as to produce a hot airflow towards the cooking chamber, characterized in that the cooking apparatus further comprises: measuring means (14) arranged to generate a signal correlated to the speed of the motor (13) driving the fan, processing means (15) arranged to: receive a signal (V) correlated to the speed measurement generated by the measuring means (14); process this signal (V) to determine a rotation speed of the motor (13);generate a command (C) to the motor (13) in order to control the motor's speed; transmit said command (C) to the motor (13). Figure for the abbreviation: Fig. 3;

Description

Title of the invention: Hot air cooking appliance with a speed-controlled motor Technical field

[0001] The present invention relates to cooking appliances, more precisely to hot air fryer type cooking appliances allowing food to be cooked using very little oil, or even no oil at all. State of the art

[0002] Hot air cooking appliances are known comprising a cooking chamber intended to receive food to be cooked or heated, a heating element arranged to produce heat and a fan arranged to generate a flow of air coming into contact with the heating element so as to produce a flow of hot air and a motor for rotating the fan. This flow of hot air is then directed towards the cooking chamber in order to cook or heat the food.

[0003] However, it was found that the fan speed was not constant and could change depending on the air temperature in the fan environment. Indeed, since hot air is less dense than cold air, when the temperature increases in the fan environment then the load applied to the fan blades decreases and the fan speed increases.

[0004] The fan speed of such a hot air cooking appliance may also vary depending on the frequency or voltage of the electrical network supplying the fan drive motor of the electrical appliance. Thus, for the same temperature in the environment of the fan, the fan speed will be faster in countries where the electrical network frequency is 60 Hz than in countries where the electrical network frequency is 50 Hz.

[0005] These variations in fan speed can cause problems when preparing certain culinary recipes.

[0006] Indeed, for certain cooking methods (cakes for example), too fast an air flow can dry out or burn the surface of the food preparation before the inside is cooked. For other foods, for example fries, a very hot and very powerful air flow is required to sear as quickly as possible. Summary of the invention

[0007] The present invention aims to remedy all or part of these drawbacks.

[0008] The technical problem underlying the invention consists in proposing a hot air cooking appliance comprising a fan whose speed is constant independently of the load applied to the fan and independently of the frequency or voltage of the electrical network supplying the cooking appliance. Another aim of the invention is to be able to adapt the speed of the fan according to the recipe to be prepared by the cooking appliance.

[0009] To this end, the invention relates to a hot air cooking appliance, in particular of the hot air fryer type, comprising: - a cooking chamber intended to receive food to be cooked or heated, - a heating element arranged to produce heat, - an air circulation device comprising a fan and a motor arranged to drive the fan, and arranged to generate a flow of air coming into contact with the heating element so as to produce a flow of hot air towards the cooking chamber, characterized in that the cooking appliance further comprises: - measuring means arranged to generate a signal correlated to the speed of the motor driving the fan, - processing means arranged for: • receive a signal correlated to the speed measurement generated by the measuring means; • process this signal to determine a motor rotation speed; • generate a command to the motor in order to control the motor speed, • transmit said command to the motor.

[0010] This arrangement makes it possible to eliminate variations in fan speed, in particular due to variations in load that may be applied to the fan. This also allows the cooking appliance to offer different fan rotation speeds and thus increase the possibilities for producing recipes using the cooking appliance.

[0011] According to one embodiment, the means for measuring the speed of the motor comprise an optical sensor, a magnetic sensor or means for measuring the current in the winding of the motor.

[0012] According to one embodiment, the motor is of the AC type and the processing means comprise a triac for controlling the speed of the motor.

[0013] The triac is a power electronic component allowing the invention to be implemented at lower cost.

[0014] According to one embodiment, the motor is of the DC type and the processing means carry out control by pulse width modulation.

[0015] According to one embodiment, the motor is of the brushless type.

[0016] This type of motor allows for large speed variation ranges.

[0017] According to one embodiment, the processing means are arranged to in-

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[0026] interrupting the power supply to the heating element when, during the execution of a recipe program, the processing means receive a measured speed measurement signal indicating a speed variation going beyond a predetermined threshold. This arrangement makes it possible to increase the operational safety of the cooking appliance, particularly when the measured speed is too low, even when stopped, or too high. According to one embodiment, the processing means are arranged to control the fan at the same speed regardless of the frequency of the electrical network supplying the electric cooking appliance. This arrangement makes it possible to manufacture the same cooking appliance and export it to different countries that do not have the same electricity supply frequency. The present invention also relates to a method of using a hot air cooking appliance according to one of the preceding characteristics, comprising the following steps: - have a database of recipe programs that can be carried out by the hot air cooking appliance, - select a recipe program on a user interface linked to the cooking appliance, - determine, from the database, a fan rotation speed to be applied according to the selected recipe program, - control the motor at the determined speed. This arrangement allows you to more precisely adjust the cooking parameters for making the recipe. According to one implementation of the method, the user selects a recipe program for making yogurts, or a recipe program for dehydrating food or a low-temperature cooking program, and the processing means control the motor at a speed of between 120 and 500 revolutions per minute. This arrangement allows you to create recipes that were previously not easily possible with this type of hot air cooking appliance. According to one implementation of the method, the user selects a recipe program requiring a plurality of fan rotation speeds for its implementation, and the processing means control the motor at a first speed determined by the selected recipe program, then control the motor at a second determined speed different from the first speed. This arrangement further allows the cooking appliance to offer new recipes while making them easier to make. Brief description of the figures

[0027] The aims, aspects and advantages of the present invention will be better understood from the description given below of a particular embodiment of the invention presented by way of non-limiting example, with reference to the appended drawings in which:

[0028] [Fig. 1] is a perspective view showing in section an example of a hot air fryer type cooking appliance;

[0029] [Fig.2] is a perspective view showing a preferred design of a basket of a hot air fryer type cooking appliance;

[0030] [Fig. 3] is a block diagram of the operation of the hot air cooking appliance according to the invention;

[0031] [Fig.4] is a flowchart illustrating the implementation of a method of using a hot air cooking appliance according to the invention.

[0032] In the remainder of the description, the cooking appliance consists of an example of a hot air fryer, other designs of hot air fryers existing and also being able to include the essential characteristics which are the subject of the present invention which will be detailed below.

[0033] With regard to [Fig.l], the cooking appliance 1 of the hot air fryer type comprises a shell 2 comprising an outer wall 3 provided with a rear wall 3a opposite a front face 1a of this cooking appliance 1 of the hot air fryer type. This front face 1a allows the insertion of a tank 4 and a basket 5, in the manner of a drawer, into a cooking chamber 6 arranged inside the shell 2, the tank 4 and the basket 5 being manipulated by means of a handling handle 7. This handling handle 7 not only allows the basket 5 to be manipulated alone to place it in the tank 4 or remove it from said tank 4, but also to fix the basket 5 in position in the tank 4 so as to simultaneously manipulate the tank 4 with the basket 5 for their simultaneous insertion into the cooking chamber 6 and their removal from said cooking chamber 6, in the manner of a drawer.A heating element 8 is arranged inside the shell 2, above the cooking chamber 6. An air circulation device 9 makes it possible to draw in fresh air through an air inlet 10 which is arranged on the rear wall 3a; this fresh air is conveyed to the heating element 8 in order to be heated and then, once heated, to the cooking chamber 6. This hot air enters the tank 4 then into the basket 5 by passing through the underside of the basket 5. The hot air is then discharged outside the cooking appliance 1 of the hot air fryer type, through an air outlet 11 arranged on the rear wall 3a. The air circulation device 9 comprises a fan 12 making it possible to convey the air from the air inlet 10 to the . air outlet 11 as well as a motor 13 arranged to drive the fan in rotation. These general characteristics are known on hot air fryer type cooking appliances currently on the market, reasons why they will not be detailed; those skilled in the art may, for example, refer to the hot air cooking appliances developed by the applicant, for example those marketed under the name EASY FR Y®.

[0034] With reference to [Fig. 3], the hot air cooking appliance 1 further comprises measuring means 14 arranged to generate a signal V correlated to the speed of the motor 13 driving the fan 12, and processing means 15 arranged to: - receive the signal V correlated to the speed measurement measured by the measuring means 14 of the speed of the motor 13; - process this signal V by generating a command C to the motor 13 so as to control the speed of the motor 13; - transmit said command C to motor 13.

[0035] The means 14 for measuring the speed of the motor 13 comprise, for example, an optical sensor or a magnetic sensor.

[0036] In the case of an optical sensor, the sensor will generate a signal V which will count the passage and / or interruption of a light beam by the blades and the processing means 15, by counting the number of passages and / or interruptions of the light beam, will deduce the speed of the fan 12 and therefore the speed of the motor 13.

[0037] In the case of a magnetic sensor, the sensor, for example of the Hall effect type, will generate a signal V which will record the passage of a magnet secured to one of the blades of the fan 12 and the processing means 15 will deduce the speed of the fan 12 and therefore the speed of the motor 13.

[0038] The motor 13 may be of the brushless type so as to be able to offer different speed ranges from low speeds typically between 150 rpm and 300 rpm and high speeds, typically from 300 rpm up to 3000 rpm.

[0039] In this case it is also possible for the means 14 for measuring the speed of the motor 13 to generate signals V in relation to the currents induced in the stator of the motor 13 when the rotor magnets pass through to enable the processing means 15 to directly determine the speed of the motor 13.

[0040] Once the speed has been determined by the processing means 15, the processing means 15 will generate a command C intended for the motor 13 so as to control the speed of the motor 13.

[0041] The motor 13 can be of the AC type or of the DC type.

[0042] In the case of an AC type motor, the processing means 15 comprise a triac to control motor 13 in speed.

[0043] The triac mounted as a dimmer can be used to vary the power supply to the motor 13 by varying the holding current of the motor power supply current. In order to obtain a stable motor rotation speed, the dimmer must then deliver an electrical power to the electric motor which corresponds to the speed at which the motor operates at full load, i.e. at the start of cooking.

[0044] This electrical power can be further adjusted so that it is the same regardless of the power supply frequency of the electrical network, in particular for cooking appliances 1 which can operate at a frequency of either 50 Hz or 60 Hz.

[0045] The dimmer will then adjust the electrical power to deliver an electrical power to the motor 13 which corresponds to the speed at which the motor 13 operates at full load for operation on a power supply frequency of the electrical network of 50 Hz.

[0046] Thus, a switch to a connection to a 60 Hz power supply network will not disturb the rotation speed of the motor 13 driving the fan 12, nor will the reduction in load during the rise in temperature during cooking.

[0047] From this maximum rotation speed of the motor 13, the configuration of the dimmer makes it possible to reduce the electrical power sent to the motor 13 and therefore its speed for the needs of a recipe program.

[0048] In the case of a DC type motor, the processing means 15 carry out control by pulse width modulation.

[0049] As for a triac mounted as a dimmer, the duty cycle of the pulse width modulation control can be adjusted to deliver the same power to the motor 13 which corresponds to the speed at which the motor 13 operates at full load for operation on a power supply frequency of the electrical network of 50 Hz.

[0050] From this maximum rotation speed of the motor 13, a reduction in the duty cycle makes it possible to reduce the electrical power sent to the motor 13 and therefore its speed for the needs of a recipe program.

[0051] It may also be provided that when, during the execution of a recipe program, the processing means 15 receive a signal V correlated to the speed measurement indicating a speed variation going beyond a predetermined threshold, then the processing means 15 interrupt the electrical supply to the heating element 8.

[0052] This variation in speed, which can reach a threshold ranging from 20% to 100%, may be the consequence of a malfunction, in particular which may be due to friction or mechanical blocking of the blades of the fan 12. The electrical power supply of the heating element 8 is then interrupted so as not to risk burning the culinary preparation.

[0053] The present invention also relates to a method of using a hot air cooking appliance 1 as described above.

[0054] A first step of this method consists of having a database of recipes that can be produced by the hot air cooking appliance 1;

[0055] This database can be accessible locally and recorded directly in a memory of the cooking appliance 1 or remotely and accessible via communication means, in particular a wireless network, with which the processing means 15 interact.

[0056] The second step consists of selecting a recipe program on a user interface linked to the cooking appliance 1. This user interface can be directly on the cooking appliance 1 or can be on a remote terminal capable of communicating with the processing means 15 of the cooking appliance 1.

[0057] The third step consists of determining, from the database, a rotation speed of the fan to be applied according to the selected recipe program. For each recipe program in the database, at least one rotation speed of the motor 13 driving the fan 12 is associated. Conventionally, this speed may be the maximum rotation speed applied to the motor to ignore load variations and different frequencies of the power supply network, but this speed may also be lower than this maximum speed for certain recipe programs, in particular for making yogurts, or a food dehydration recipe program or a low-temperature cooking program.

[0058] These speeds can for example be between 120 and 500 revolutions per minute.

[0059] The fourth step will consist of controlling the motor 13 to the determined speed.

[0060] Certain recipe programs may also require the use of a plurality of fan rotation speeds for their implementation.

[0061] Once such a recipe program has been selected by the user, the processing means 15 control the motor 13 to a first speed determined by the selected recipe program, then the processing means 15 control the motor 13 to a second determined speed different from the first speed.

[0062] The moment at which the motor must change from its first determined speed to its second determined speed can be given directly by the recipe program recorded in the database or can be determined by the processing means as a function of a condition to be achieved recorded in the database.

[0063] Of course, the invention is in no way limited to the embodiment described and illustrated which has been given only as an example. Modifications remain possible, in particular from the point of view of the constitution of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

Claims

1. Hot air cooking appliance (1), in particular of the hot air fryer type, comprising: - a cooking chamber (6) intended to receive food to be cooked or heated, - a heating element (8) arranged to produce heat, - an air circulation device (9) comprising a fan (12) and a motor (13) arranged to drive the fan (12), and arranged to generate a flow of air coming into contact with the heating element (8) so as to produce a flow of hot air towards the cooking chamber (6), characterized in that the cooking appliance (1) further comprises: - measuring means (14) arranged to generate a signal correlated to the speed of the motor (13) driving the fan, - processing means (15) arranged to: • receive a signal (V) correlated to the speed measurement generated by the measuring means (14);• process this signal (V) to determine a rotation speed of the motor (13); • generate a command (C) to the motor (13) so as to control the motor in speed, • transmit said command (C) to the motor (13).;

2. Hot air cooking appliance (1) according to claim 1, wherein the means (14) for measuring the speed of the motor (13) comprise an optical sensor, a magnetic sensor or means for measuring the current in the winding of the motor.

3. Hot air cooking appliance (1) according to one of claims 1 or 2 in which the motor (13) is of the AC type and the processing means (15) comprise a triac for controlling the speed of the motor (13).

4. Hot air cooking appliance (1) according to one of claims 1 or 2 in which the motor (13) is of the DC type and the processing means (15) carry out control by pulse width modulation.

5. Hot air cooking appliance (1) according to one of claims 1 to 4 in which the motor (13) is of the brushless type.

6. Hot air cooking appliance (1) according to one of claims 1 to 5, in which the processing means (15) are arranged to interrupt the electrical supply to the heating element (8) when, during the execution of a recipe program, the processing means (15) receive a measured speed measurement signal indicating a speed variation going beyond a predetermined threshold.

7. Hot air cooking appliance (1) according to one of claims 1 to 6, in which the processing means (15) are arranged to control the fan (12) at the same speed regardless of the frequency of the electrical network supplying the electric cooking appliance (1).

8. Method for using a hot air cooking appliance (1) according to one of claims 1 to 7, comprising the following steps: - Having a database (DB) of recipe programs (RPx) that can be carried out by the hot air cooking appliance (1), - Selecting a recipe program (RPx) on a user interface (UI) linked to the cooking appliance (1), - Determining, from the database (DB), a rotation speed of the fan (12) to be applied according to the selected recipe program (RPx), - Ensuring the motor (13) at the determined speed.

9. Method of use according to claim 8, during which: - the user selects a recipe program (RPx) for making yogurts, or a recipe program for dehydrating food or a low-temperature cooking program, - the processing means (15) control the motor (13) at a speed of between 120 and 500 revolutions per minute.

10. Method of use according to claim 8, during which: - the user selects a recipe program (RPx) requiring a plurality of rotation speeds of the fan (12) for its realization, and the processing means (15) control the motor (13) at a first speed determined by the selected recipe program, then the processing means (15) control the motor to a second determined speed different from the first speed.

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