Hot-air cooking appliance with speed-servo motor

Abstract

The invention relates to a hot-air cooking appliance, in particular a hot-air fryer-type cooking appliance, comprising: a cooking chamber for receiving food to be cooked or heated; a heating element (8) arranged to generate heat; -air circulation means comprising a ventilator (12) and a motor (13) arranged to drive the ventilator (12) and arranged to generate a flow of air in contact with the heating element (8) in order to generate a flow of hot air in the direction of the cooking chamber, characterized in that the motor (13) is arranged to drive the ventilator (12) and to generate a flow of hot air in contact with the heating element (8). The cooking appliance further comprises:-measuring means (14) arranged to generate a signal related to the speed of a motor (13) driving the ventilator; -processing means (15) arranged to: o receive a signal (V) generated by the measuring means (14) relating to a speed measurement; o processing the signal (V) to determine the rotational speed of the electric machine (13); o generating a command (C) to the motor (13) in order to servo the motor at a speed; o transmitting a command (C) to the motor (13).

Description

Technical Field

[0001] This invention relates to cooking equipment, and more particularly to a hot air fryer-type cooking equipment that allows food cooking to be performed using very little or no oil. Background Technology

[0002] A hot air cooking device is known to include: a cooking chamber for receiving food to be cooked or heated; a heating element arranged to generate heat; a ventilator arranged to generate an airflow in contact with the heating element to produce a hot airflow; and a motor for driving the ventilator to rotate. The hot airflow is then directed towards the cooking chamber to cook or heat the food.

[0003] However, it has been found that the speed of a ventilator is not constant and may evolve depending on the air temperature in the ventilator's environment. In fact, hot air is less dense than cold air, and as the temperature in the ventilator's environment increases, the load applied to the ventilator blades decreases and the ventilator's speed increases.

[0004] The speed of the ventilator in this type of hot air cooking equipment can also vary depending on the frequency or voltage of the power grid supplying power to the ventilator's drive motor. Therefore, for the same ambient temperature, the ventilator speed will be faster in countries with a power grid frequency of 60 Hz than in countries with a power grid frequency of 50 Hz.

[0005] These speed variations in the ventilator can cause problems when executing certain cooking recipes.

[0006] In fact, for some cooking methods (such as cakes), too fast an airflow can cause the surface of the prepared food to dry or burn before the inside is cooked. For other foods, such as French fries, very hot and very strong airflow is needed to fry them as quickly as possible. Summary of the Invention

[0007] The present invention aims to overcome all or part of these disadvantages.

[0008] The technical problem upon which this invention is based is to provide a hot air cooking device comprising a ventilator whose speed is constant and independent of the load applied to the ventilator and the frequency or voltage of the power grid supplying power to the cooking device. Another object of this invention is to adapt the speed of the ventilator to the recipe to be prepared by the cooking device.

[0009] Therefore, the present invention relates to a hot air cooking device, particularly a hot air fryer type cooking device, comprising: - A cooking cavity for storing food to be cooked or heated; - A heating element, the heating element being arranged to generate heat; - An air circulation device, comprising a ventilator and a motor, the motor being arranged to drive the ventilator and to generate an airflow in contact with the heating element to produce a hot airflow toward the cooking cavity. The cooking device is characterized in that it further includes: - A measuring device arranged to generate a signal related to the speed of the motor driving the ventilator; - Processing device, said processing device being arranged as follows: o Receives speed measurement-related signals generated by the measuring device; o Process the signal to determine the rotational speed of the motor; o Generates commands to be sent to the motor in order to servo the motor at a speed; o Transmit the command to the motor.

[0010] This setup allows for the elimination of speed variations in the ventilator, especially those caused by changes in load that may be applied to it. It also allows the cooking equipment to offer different rotational speeds for the ventilator and thus increases the likelihood of the cooking equipment executing recipes.

[0011] According to one embodiment, the measuring device for measuring the speed of the motor includes an optical sensor, a magnetic sensor, or a measuring device for measuring the current in the coil of the motor.

[0012] According to one embodiment, the motor is AC, and the processing device includes a triac (SCR) for servoing the motor at speed.

[0013] The three-terminal bidirectional thyristor switching element is a power electronic component that allows the present invention to be implemented at a lower cost.

[0014] According to one embodiment, the motor is DC type, and the processing device implements pilot control via pulse width modulation.

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

[0016] This type of motor allows for a wide range of speed variations.

[0017] According to one embodiment, the processing device is arranged to interrupt power supply to the heating element when, during the execution of a recipe procedure, the processing device receives a measurement speed signal indicating that the speed change exceeds a predetermined threshold.

[0018] This setting allows for enhanced safety of the cooking equipment, especially when the measuring speed is too low, or even stops, or too high.

[0019] According to one embodiment, the processing device is arranged to servo the ventilator at the same speed, regardless of the frequency of the power supply network of the electric cooking equipment.

[0020] This setup allows the same cooking equipment to be manufactured and exported to different countries with different power grid frequencies.

[0021] According to one embodiment, the hot air cooking appliance includes a user interface for selecting recipe programs, and the processing device is arranged to access a database of recipe programs that can be executed by the hot air cooking appliance.

[0022] The database can be directly integrated into the device or it can be located on a remote server and accessed from a remote connection between the hot air cooking device and the server.

[0023] The present invention also relates to a method for using a hot air cooking device according to any one of the foregoing features, comprising the following steps: - Establish a database of recipe programs that can be executed by the hot air cooking equipment; - Select a recipe program on the user interface associated with the cooking appliance; - Determine the rotational speed of the ventilator to be applied from the database according to the selected formula procedure; - To determine the speed of the servo motor.

[0024] This setting allows for more precise adjustment of the cooking parameters used to execute the recipe.

[0025] According to one embodiment of the method, the user selects a recipe program for making yogurt, or a food dehydration recipe program, or a sous-vide cooking program, and the processing device servos the motor at a speed between 120 rpm and 500 rpm.

[0026] This setting allows recipes that have not been easily executed using this type of hot air cooking equipment until now.

[0027] According to one embodiment of the method, the user selects a recipe program that requires multiple rotational speeds of the ventilator to execute, and the processing device servos the motor at a first speed determined by the selected recipe program, and then the processing device servos the motor at a second speed determined to be different from the first speed.

[0028] This setting further allows the cooking device to generate new recipes while facilitating the execution of these new recipes. Attached Figure Description

[0029] The objects, aspects, and advantages of the present invention will be better understood by referring to the following description of specific embodiments of the invention, given by way of non-limiting example, in which: Figure 1 This is a perspective view showing a cross-section of an example of a hot air fryer-type cooking appliance; Figure 2 This is a perspective view showing a preferred design of the basket for a hot air fryer-type cooking appliance; Figure 3 This is a schematic diagram of the operation of the hot air cooking device according to the present invention; Figure 4 This is a flowchart illustrating an embodiment of a method for using a hot air cooking device according to the present invention. Detailed Implementation

[0030] In the following description, the cooking apparatus is exemplified by a hot air fryer, which differs from existing hot air fryer designs that may also include the basic features of the subject matter of this invention, which will be described in detail below.

[0031] Reference Figure 1The air fryer-type cooking appliance 1 includes a shell 2, which includes an outer wall 3. The outer wall 3 is equipped with a rear wall 3a, which is opposite to the front surface 1a of the air fryer-type cooking appliance 1. The front surface 1a allows a reservoir 4 and a basket 5 to be inserted into a cooking chamber 6 in a drawer-like manner. The cooking chamber 6 is arranged inside the shell 2. The reservoir 4 and the basket 5 are operated by means of a handle 7. The handle 7 allows not only individual operation of the basket 5 to place it in or remove it from the reservoir 4, but also simultaneous operation of the reservoir 4 and the basket 5 to simultaneously insert them into and remove them from the cooking chamber 6 in a drawer-like manner. A heating element 8 is arranged inside the shell 2, above the cooking chamber 6. An air circulation device 9 allows fresh air to be drawn in through an air inlet 10, which is arranged on the rear wall 3a; this fresh air is directed toward the heating element 8 for heating, and then, once heated, is directed toward the cooking chamber 6. The hot air enters the reservoir 4 and then passes through the lower part of the basket 5 into the basket 5. The hot air is then compressed to the outside of the air fryer-type cooking appliance 1 through the air outlet 11, which is disposed on the rear wall 3a. The air circulation device 9 includes a ventilator 12 and a motor 13, the ventilator 12 allowing air to be delivered from the air inlet 10 to the air outlet 11, and the motor 13 being arranged to drive the ventilator to rotate. These general features are known in currently commercially available air fryer-type cooking appliances, and therefore will not be described in detail; those skilled in the art can refer, for example, to the air fryer-type cooking appliance developed by the applicant, such as the one named EASY FRY. ® Hot air cooking equipment for sale.

[0032] Reference Figure 3 The hot air cooking device 1 also includes a measuring device 14 arranged to generate a signal V related to the speed of the motor 13 driving the ventilator 12, and a processing device 15 arranged to: - Receive a signal V related to the speed measurement measured by the measuring device 14 used to measure the speed of motor 13; - The signal V is processed by generating a command C to be sent to motor 13 in order to servo motor 13 at speed; - Transmit the instruction C to motor 13.

[0033] The measuring device 14 used to measure the speed of motor 13 includes, for example, an optical sensor or a magnetic sensor.

[0034] In the case of an optical sensor, the sensor will generate a signal V that counts the passage and / or interruption of the beam from the blade, and the processing device 15 will deduce the speed of the ventilator 12 and thus the speed of the motor 13 by counting the number of passages and / or interruptions of the beam.

[0035] In the case of a magnetic sensor, such as a Hall effect sensor, a signal V will be generated that counts the passage of a magnet integrated with one of the blades of the ventilator 12, and the processing device 15 will thereby deduce the speed of the ventilator 12 and thus the speed of the motor 13.

[0036] Motor 13 can be brushless so that different speed ranges can be offered, from low speeds typically between 150 rpm and 300 rpm to high speeds typically between 300 rpm and 3000 rpm.

[0037] In this case, it is also possible that the measuring device 14 used to measure the speed of the motor 13 generates a signal V related to the current induced in the stator of the motor 13 when the rotor magnet passes by, so as to allow the processing device 15 to directly determine the speed of the motor 13.

[0038] Once the processing device 15 determines the speed, it will generate a command C to be sent to the motor 13 in order to servo the motor 13 at the speed.

[0039] Motor 13 can be either AC or DC.

[0040] In the case of an AC motor, the processing device 15 includes a three-terminal bidirectional thyristor switch element for servoing the speed of the motor 13.

[0041] The three-terminal bidirectional thyristor switch element installed in the voltage regulator can be used to change the power supply of motor 13 by changing the holding current of the motor's power supply current. In order to obtain a stable rotational speed of the motor, the voltage regulator needs to supply electrical power to the motor, which corresponds to the speed of the motor when it is working at full load, that is, at the start of cooking.

[0042] The power can be further adjusted to ensure that the power is the same regardless of the power grid frequency, especially for cooking equipment 1 that can operate at both 50Hz and 60Hz frequencies.

[0043] Then, the voltage regulator will adjust the electrical power to supply electrical power to the motor 13, which corresponds to the speed at which the motor 13 operates at full load, so as to operate at the 50Hz mains power frequency.

[0044] Therefore, switching to a 60Hz power supply network will not interfere with the rotational speed of the motor 13 driving the ventilator 12, nor will it interfere with the load reduction during the temperature rise period of cooking.

[0045] Starting from the maximum rotational speed of motor 13, the voltage regulator is designed to reduce the electrical power supplied to motor 13 and thus its speed to meet the requirements of the formulation process.

[0046] In the case of a DC motor, the processing device 15 implements pilot control via pulse width modulation.

[0047] The same applies to the three-terminal bidirectional thyristor switching element installed in the voltage regulator, which can adjust the duty cycle controlled by the pilot via pulse width modulation to provide the same power to motor 13, corresponding to the speed at which motor 13 operates at full load, so as to operate at the 50Hz mains power frequency.

[0048] Starting from the maximum rotational speed of motor 13, the reduction in duty cycle allows for a reduction in the electrical power supplied to motor 13 and thus a reduction in its speed to meet the requirements of the formulation process.

[0049] It can also be specified that when the processing device 15 receives a speed measurement-related signal V indicating that the speed change exceeds a predetermined threshold during the execution of the recipe procedure, the processing device 15 interrupts the power supply to the heating element 8.

[0050] Such a speed variation, which can reach 20% to 100% of the threshold, could be a consequence of a malfunction, especially one caused by friction or mechanical locking of the blades of ventilator 12. Power to heating element 8 should then be interrupted to avoid the risk of burning the cooked food.

[0051] The present invention also relates to a method for using the hot air cooking device 1 as described above.

[0052] The first step of this method is to set up a recipe database that can be executed by the hot air cooking device 1; The database can be accessed locally and recorded directly or remotely in the memory of the cooking device 1, and can be accessed via communication devices, especially wireless networks, with the processing device 15 interacting with these communication devices.

[0053] The second step is to select a recipe program on the user interface associated with the cooking appliance 1. This user interface can be located directly on the cooking appliance 1 or on a remote terminal that can communicate with the processing device 15 of the cooking appliance 1.

[0054] The third step is to determine the rotational speed of the ventilator to be applied from the database based on the selected recipe program. For each recipe program in the database, at least one rotational speed of the motor 13 driving the ventilator 12 is associated. Typically, this speed can be the maximum rotational speed applied to the motor so as not to take into account load variations and different frequencies of the power supply network; however, this speed may be lower than this maximum speed for some recipe programs, especially those for making yogurt, or food dehydration recipe programs or sous-vide cooking programs.

[0055] These speeds can be, for example, between 120 rpm and 500 rpm.

[0056] The fourth step is to determine the speed of the servo motor 13.

[0057] Some formulation procedures may also require the use of multiple rotation speeds of the ventilator to perform these formulation procedures.

[0058] Once the user selects this recipe program, the processing device 15 serves the motor 13 at a first speed determined by the selected recipe program, and then the processing device 15 serves the motor 13 at a second speed determined differently from the first speed.

[0059] The moment when the motor should switch from its first determined speed to its second determined speed can be given directly by the recipe program recorded in the database, or it can be determined by the processing device based on the execution conditions recorded in the database.

[0060] Of course, the present invention is by no means limited to the embodiments described and shown only by way of example. Modifications can be made without departing from the scope of protection of the present invention, particularly from the viewpoint of the construction of various elements or by substituting technical equivalents.

Claims

1. A hot air cooking device (1), particularly a hot air fryer type cooking device, comprising: - Cooking cavity (6), the cooking cavity (6) is used to store food to be cooked or heated; - Heating element (8), said heating element (8) is arranged to generate heat; - An air circulation device (9) comprising a ventilator (12) and a motor (13) arranged to drive the ventilator (12) and to generate an airflow in contact with the heating element (8) to generate a hot airflow toward the cooking cavity (6). The cooking device (1) is characterized in that it further includes: - A measuring device (14) arranged to generate a signal related to the speed of the motor (13) driving the ventilator; - Processing device (15), said processing device (15) being arranged as follows: o Receives a speed measurement-related signal (V) generated by the measuring device (14); o Process the signal (V) to determine the rotational speed of the motor (13); o Generates a command (C) to be sent to the motor (13) in order to servo the motor at a speed; o Transmit the instruction (C) to the motor (13).

2. The hot air cooking device (1) according to claim 1, wherein, The measuring device (14) for measuring the speed of the motor (13) includes an optical sensor, a magnetic sensor, or a measuring device for measuring the current in the coil of the motor.

3. The hot air cooking apparatus (1) according to any one of claims 1 or 2, wherein, The motor (13) is AC type, and the processing device (15) includes a three-terminal bidirectional thyristor switch element for servoing the motor (13) at speed.

4. The hot air cooking apparatus (1) according to any one of claims 1 or 2, wherein, The motor (13) is DC type, and the processing device (15) implements pilot control via pulse width modulation.

5. The hot air cooking apparatus (1) according to any one of claims 1 to 4, wherein, The motor (13) is a brushless type.

6. The hot air cooking apparatus (1) according to any one of claims 1 to 5, wherein, The processing device (15) is arranged to interrupt the power supply to the heating element (8) when it receives a measurement speed measurement signal indicating that the speed change exceeds a predetermined threshold during the execution of the recipe procedure.

7. The hot air cooking apparatus (1) according to any one of claims 1 to 6, wherein, The processing device (15) is arranged to servo the ventilator (12) at the same speed, regardless of the frequency of the power supply network of the electric cooking appliance (1).

8. The cooking apparatus according to any one of claims 1 to 7, comprising a user interface for selecting a recipe program, and the processing device (15) being arranged to access a database of recipe programs (RPx) that can be executed by the hot air cooking apparatus.

9. A method for using the hot air cooking apparatus (1) according to claim 8, comprising the following steps: - Set up a database (DB) of recipe programs (RPx) that can be executed by the hot air cooking equipment (1); - Select a recipe program (RPx) on the user interface (UI) associated with the cooking appliance (1); - Determine the rotational speed of the ventilator (12) to be applied from the database (DB) according to the selected formulation procedure (RPx); - Servo the motor (13) at the determined speed.

10. The method of use according to claim 9, wherein: - Users can choose a recipe program (RPx) for making yogurt, or a food dehydration recipe program or a sous-vide cooking program; - The processing device (15) servos the motor (13) at a speed between 120 rpm and 500 rpm.

11. The method of use according to claim 9, wherein: - The user selects a recipe procedure (RPx) that requires multiple rotational speeds of the ventilator (12) to execute; and - The processing device (15) servos the motor (13) at a first speed determined by the selected recipe program; then - The processing device (15) servos the motor at a determined second speed, which is different from the first speed.

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