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 flow of hot air 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 rotational 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 apparatus with a speed-controlled motor technical field

[0001] The present invention relates to cooking appliances, more specifically to hot air fryer type cooking appliances which allow 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 to comprise a cooking chamber for holding food to be cooked or heated, a heating element arranged to produce heat, and a fan arranged to generate an airflow that comes into contact with the heating element so as to produce a hot airflow, and a motor for rotating the fan. This hot airflow is then directed towards the cooking chamber to cook or heat the food.

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

[0004] The fan speed of such a hot air cooking appliance can also vary depending on the frequency or voltage of the electrical network supplying the fan drive motor. Thus, for the same temperature in the fan's environment, the fan speed will be higher 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 in the execution of certain culinary recipes.

[0006] Indeed, for certain types of cooking (cakes, for example), too rapid an airflow can dry out or burn the surface of the food before the inside is cooked. For other foods, such as French fries, a very hot and powerful airflow is needed to sear them 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 of proposing a hot air cooking device comprising a fan whose speed is constant regardless of the load applied to the fan and regardless of the frequency or voltage of the electrical network supplying the cooking appliance. Another objective of the invention is to be able to adapt the fan speed according to the recipe to be prepared by the cooking appliance.

[0009] To this end, the invention relates to a hot air cooking apparatus, in particular of the hot air fryer type, comprising: - a cooking chamber intended to hold 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 an airflow 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 devices arranged to generate a signal correlated to the speed of the motor driving the fan, - processing facilities arranged for: • receive a signal correlated to the speed measurement generated by the means of measure; • process this signal to determine a motor rotation speed; • generate a command to the motor in order to control the motor's speed, • transmit said command to the motor.

[0010] This arrangement eliminates variations in fan speed, particularly those caused by load variations that may be applied to the fan. It also allows the cooking appliance to offer different fan rotation speeds, thus increasing the range of recipes that can be prepared using the cooking appliance.

[0011] According to one embodiment, the means for measuring the speed of the motor include 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 include a triac to control the motor speed.

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

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

[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 interrupt the power supply to the heating element when, during the execution of a recipe program, the processing means receive a measured speed signal indicating a speed variation exceeding a predetermined threshold.

[0018] This provision makes it possible to strengthen the operational safety of the cooking appliance, in particular when the measured speed is too low, or even stopped, or too high.

[0019] According to one embodiment, the processing means are arranged to control the fan at the same speed regardless of the frequency of the electrical power supply network of the electric cooking appliance.

[0020] This provision makes it possible to manufacture the same cooking appliance and to export it to different countries that do not have the same frequency of supply of the electrical network.

[0021] 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: - to have a database of recipe programs that can be prepared using 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 apply according to the selected recipe program, - control the motor to the determined speed.

[0022] This provision allows for more precise adjustment of the cooking parameters for the preparation of the recipe.

[0023] According to one embodiment of the process, the user selects a recipe program for making yogurt, or a food dehydration recipe program or a low-temperature cooking program, and the processing means control the motor at a speed between 120 and 500 revolutions per minute.

[0024] This arrangement makes it possible to make recipes that were previously not easily achievable with this type of hot air cooking appliance.

[0025] According to one embodiment of the method, the user selects a recipe program requiring a plurality of fan rotation speeds for its execution, and the processing means control the motor to a first speed determined by the selected recipe program, then control the motor to a second determined speed different from the first speed.

[0026] This feature allows the cooking appliance to offer even more new recipes while making them easier to prepare. Brief description of the figures

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

[0028] Fig. 1 is a perspective view showing in cross-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 for an air fryer type cooking appliance;

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

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

[0032] In the following description, the cooking apparatus consists of an example of a hot air fryer, other designs of hot air fryers exist and may also include the essential characteristics of the present invention which will be detailed below.

[0033] With regard to [Fig. 1], the air fryer-type cooking appliance 1 comprises a shell 2 having an outer wall 3 with a rear wall 3a opposite a front face la of this air fryer-type cooking appliance 1. This front face la allows the insertion of a bowl 4 and a basket 5, in the manner of a drawer, into a cooking chamber 6 arranged inside the shell 2, the bowl 4 and the basket 5 being handled by means of a handling handle 7. This handling handle 7 allows not only the basket 5 to be handled alone to place it in the bowl 4 or to remove it from said bowl 4, but also to secure the basket 5 in position in the bowl 4 so as to simultaneously handle the bowl 4 and 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 draws in fresh air through an air inlet 10 located on the rear wall 3a; this fresh air is directed to the heating element 8 to be heated and then, once heated, to the cooking chamber 6. This hot air enters the tank 4 and then the basket 5 via the underside of the basket 5. The hot air is then expelled from the air fryer 1 through an air outlet 11 located on the rear wall 3a. The air circulation device 9. includes a fan 12 for conveying air from the air inlet 10 to the air outlet 11 and 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, for which reason they will not be detailed; the person 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 apparatus 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 for the motor 13 in order to control the speed of the motor 13; - transmit said command C to motor 13.

[0035] The means for measuring the speed of the motor 13 14 include, 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 count the passage of a magnet attached 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 can 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 that the means of measuring the speed of the motor 13 14 generate signals V in relation to the currents induced in the stator of the motor 13 as the rotor magnets pass by to allow the processing means 15 to directly determine the speed of the motor 13.

[0040] Once the speed is determined by the processing means 15, the processing means 15 will generate a command C for the motor 13 in order to control the motor 13 in speed.

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

[0042] In the case of an AC type motor, the processing means 15 include a triac for controlling the speed of the motor 13.

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

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

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

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

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

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

[0049] As with 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 an electrical supply frequency 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 can 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 exceeding a predetermined threshold, then the processing means 15 interrupt the power supply to the heating element 8.

[0052] This speed variation, which can reach a threshold ranging from 20% to 100%, can be the result of a malfunction, in particular due to friction or mechanical blockage of the fan blades 12. The electrical supply to the heating element 8 is then interrupted in order to avoid the risk of burning the food 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 in this process consists of having a database of recipes that can be made by the hot air cooking device 1;

[0055] This database can be accessed locally and recorded directly in a memory of the cooking appliance 1 or remotely and accessed via means of communication, in particular 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 that can communicate with the processing means 15 of the cooking appliance 1.

[0057] The third step consists of determining, from the database, a fan rotation speed 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 can be the maximum rotation speed applied to the motor to disregard load variations and different frequencies of the power supply network, but this speed can also be lower than this maximum speed for certain recipe programs, in particular for making yogurt, 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 at the determined speed.

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

[0061] Once such a recipe program has been selected by the user, 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 13 at a second determined speed different from the first speed.

[0062] The moment at which the motor must switch from its first determined speed to its second determined speed can be directly given by the recipe program stored in the database or can be determined by the processing methods based on 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 by way of example. Modifications remain possible, particularly with regard to the composition of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

Demands

1. Hot air cooking apparatus (1), in particular of the type hot air fryer 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 an airflow coming into contact with the heating element (8) so as to produce a hot airflow towards the cooking chamber (6), the cooking apparatus (1) further comprising: - 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's speed, • transmit said command (C) to the motor (13), the cooking appliance being characterized in that the processing means (15) are arranged to interrupt the power supply to the heating element (8) when, during the execution of a recipe program, the processing means (15) receive a measured speed signal indicating a speed variation exceeding a predetermined threshold.

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

3. Hot air cooking apparatus (1) according to any one of claims 1 or 2 wherein the motor (13) is of the AC type and the processing means (15) include a triac for controlling the speed of the motor (13).

4. Hot air cooking apparatus (1) according to any one of claims 1 or 2 wherein the motor (13) is of the DC type and the processing means (15) achieve pulse width modulation control.

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

6. Hot air cooking appliance (1) according to any one of claims 1 to 5, wherein the processing means (15) are arranged to control the fan (12) at the same speed regardless of the frequency of the electrical supply network of the electric cooking appliance (1).

7. Method of using a hot air cooking appliance (1) in particular of the type hot air fryer 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 an airflow coming into contact with the heating element (8) so as to produce a hot airflow towards the cooking chamber (6), the cooking appliance (1) further comprising: - 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 speed, • transmit said command (C) to the motor (13), said process comprising the following steps: - Having a database (DB) of recipe programs (RPx) that can be carried out by the hot air cooking device (1), - Selecting a recipe program (RPx) on a user interface (UI) linked to the cooking device (1), - Determining, from the database (DB), a fan (12) rotation speed to be applied according to the selected recipe program (RPx), - Controlling the motor (13) to the determined speed.

8. A method of use according to claim 7, wherein: - the user selects a recipe program (RPx) for making yogurt, or a food dehydration recipe program or a low temperature cooking program, - the processing means (15) control the motor (13) at a speed between 120 and 500 revolutions per minute.

9. A method of use according to claim 7, wherein: - the user selects a recipe program (RPx) requiring a plurality of fan (12) rotation speeds for its execution, and - 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 to a second determined speed different from the first speed.

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