RU237460U1 - Induction heater for hookah mixtures - Google Patents

Abstract

This utility model relates to smoking devices with electric heating elements designed for the automatic heating of hookah mixtures. The primary objective of the utility model is to increase the heating rate and reliability of the heater compared to resistive heaters. The claimed induction heater comprises an inductor and a conductor consisting of a set of metal plates stacked on top of one another. The plates are made of magnetic and non-magnetic metals with holes for air flow, ensuring convection of the bowl and hookah mixture. The magnetic metal plates are heated by eddy currents and transfer heat to the non-magnetic metal plates through conduction and radiation. Heat from the non-magnetic plates is transferred to the hookah mixture and the hookah bowl through convection, conduction, and radiation. This design enables high heating rates of the hookah mixture, a lower operating temperature of the heater, increased reliability and safety of the device, and improved flavor and vapor production stability.

Description

Field of technology

The utility model relates to the field of smoking devices with electric heating elements and can be used to modernize a classic hookah with the ability to automatically heat and maintain a set temperature of a hookah smoking mixture placed inside the hookah bowl.

State of the art

Hookah heating devices using electric heating elements maintain the desired mixture temperature in automatic or semi-automatic mode. In semi-automatic mode, the devices only control the heater power without adjusting the temperature, while in fully automatic mode, the heater power is adjusted based on feedback from one or more temperature sensors.

The closest analogue to the solution under consideration is a device for heating hookah tobacco, disclosed in patent RU 2801448 C1 dated April 14, 2022. This known device contains two separate heaters located at some distance from each other inside a flat-bottomed metal cylinder and utilizes resistive heating using nichrome wire. To ensure the required heating of the bowl containing the hookah smoking mixture, the lower heater transfers heat through conduction, while the upper heater generates convective heating of the mixture.

To achieve the required convection heating level, the upper heater must be heated to a temperature of 500-800°C. The temperature of the outer surface of the metal disc in the area of the lower heater, which contacts the bowl, is approximately 200-230°C, while the temperature of the lower heater wire can reach 300-400°C. Due to the high inertia of the lower heater, it is difficult to ensure the required rate of heat transfer to the disc's surface, leading to significant temperature fluctuations when the user inhales and making it difficult to maintain the required heat level in the hookah mixture. High operating temperatures also accelerate wear on resistive heaters, shortening their lifespan.

Another well-known device is the Nevo Pure (https://aeon-shisha.com/en/nevo-pure-hmd, first saved on web.archive.org on September 23, 2023), which is installed on a hookah bowl to automatically heat the mixture. The device is equipped with a power regulator and a temperature sensor, allowing it to automatically adjust the heater power based on the sensor's readings. However, a drawback of this device is the long heating time of the hookah mixture, approximately 20 minutes, which is significantly longer than traditional heating with hookah charcoal, which takes approximately 7 minutes. Furthermore, the device also uses nichrome wire as a heater, which reduces its reliability and service life.

Disclosure of the essence of the utility model

The claimed utility model is aimed at solving the main technical problem - increasing the heating speed and reliability of the heater for hookah smoking mixtures.

The technical result of this utility model is to ensure high speed and low inertia for heating the hookah mixture in the hookah bowl, as well as to reduce the heater's operating temperature compared to resistive heating. This increases the heater's reliability and improves hookah safety.

This technical result is achieved through the use of induction heating via an inductor and a conductor consisting of a set of metal plates stacked on top of each other. The conductor's operating temperature is maintained in the range of 210-240°C, significantly reducing the risk of overheating and increasing reliability compared to resistive heaters. The heating rate, measured by a temperature sensor installed in contact with the conductor, is 1°C per second when the operating temperature reaches 180°C.

This is achieved by the Eddy currents generated in the conductor by the inductor's alternating magnetic field, which rapidly heat the conductor, which in turn transfers heat to the hookah bowl. Heat is transferred from magnetic metal plates to non-magnetic metal plates (for example, from stainless steel to aluminum), and then to the bowl, providing thermal conductivity. Additionally, air passes through the holes in the conductor when inhaled, heating it and transferring heat to the hookah mixture, providing convective heating of the bowl and the hookah smoking mixture.

This achieves optimal heating parameters for the hookah mixture, resulting in stable vapor and a rich flavor superior to traditional heating methods using coal or a resistive heater. Using simple induction heating without the proposed conductor design with its stacked plates and holes is unable to achieve a similar result.

Brief description of the drawings

The utility model is illustrated by drawings.

Fig. 1 shows the design of a device mounted on a hookah, which includes the claimed utility model:

1.1 Upper block

1.2 Hookah bowl

1.3 Lower block

1.4 Logical on-off button

1.5 Battery

1.6 Thread adapter

Fig. 2 shows the functional diagram of the induction heating system for hookah mixtures:

2.1 24V Battery

2.2 Battery Management Board (BMS)

2.3 Power Management Board

2.4 Input for external power supply

2.5 Step-down voltage converter from 24 V to 15 V

2.6 Step-down voltage converter from 24 V to 3.3 V

2.7 Voltage inverter

2.8 Inverter Drivers

2.9 Microcontroller

2.10 Logical power button

2.11 LC circuit board

2.12 Inductor and conductor

2.13 Temperature sensor

2.14 Temperature sensor ADC

In fig. Figure 3 shows the design of the inductor and conductor:

3.1 Conductor consisting of 5 plates

3.2 Thermal shield

3.3 Inductor and guide housing

3.4 Ferrites

3.5 Cover for fixing ferrites, temperature sensor and conductor

3.6 Heater outer casing

3.7 Upper heater cover

Implementation of a utility model

The utility model illustrates an induction heater of the ISMO Ring device, designed for upgrading a hookah to add the ability to automatically heat the smoking mixture in the hookah bowl and maintain a set temperature.

An example of the device implementation is shown in Fig. 1. The device is installed on threaded hookahs in place of the hookah plate using an adapter (1.6). The adapter thread sizes are: 16×1, 16×1.5, 18×1.5 mm. The device itself consists of two global blocks - the upper (1.1) and lower (1.3).

The lower block housing (1.3) contains the mounting thread (1.6), battery (1.5, 2.1), battery control board (2.2), microcontroller (2.9), control button (1.4, 2.10), voltage inverter (2.7), inverter drivers (8), power converters (2.5, 2.6), power controller board (2.3), input for external power supply (2.4), temperature sensor ADC (14).

In the upper block of the housing there is an LC circuit board (2.11), to which an inductor with a conductor attached through fasteners (2.12) is connected, and a temperature sensor (2.13) is also installed.

The top block (1.1) is removable for easy maintenance of the hookah bowl (1.2). The top block (1.1) and bottom block (1.3) are connected via guides and magnets, and spring-loaded pogo-pin contacts can be used as contacts for connecting the power outputs.

The general functional diagram of the electronic units of the device is shown in Fig. 2. The device operates as follows:

When voltage is present from a power supply unit (2.4) or battery (2.1) connected to connector (2.4) and the logical on/off button (1.4, 2.10) is held down, a signal is sent to the device's microcontroller (2.9), which may also be equipped with a WiFi and/or Bluetooth module to enable device control via a user interface application on the user's smartphone or computer. If the device was previously off, a power-on command is issued. In this case, the microcontroller generates a control signal for the unit's inverter (2.7), which converts the direct voltage and current from the battery or power supply unit into high-frequency alternating voltage and current. This is achieved using phase-correct pulse-width modulation (PWM) on two channels. A full-bridge circuit consisting of four MOSFET transistors, implemented as an H-bridge, can be used as a voltage inverter. On the central jumper of the bridge there are contact outputs leading to the LC circuit board (2.11) of the heater.

When the transistors are turned on, the signal from the microcontroller (2.9) is sent to the drivers (2.8), which turn on the transistors of the inverter bridge (2.7). The control signal must always turn on only two transistors located diagonally across the H-bridge (not in series with each other), otherwise a short circuit will occur. The PWM duty cycle cannot exceed 50%, otherwise the control signals will cross and cause a short circuit. In practice, the duty cycle cannot exceed 48-49% due to the physical delay required to charge and discharge the transistor capacitances when the channel is turned on and off.

The resulting AC voltage is transmitted via a conductor to the LC circuit board (2.11), which contains film capacitors and inductor connection contacts (2.12). The inductor and capacitors can be connected in series or parallel, allowing for the use of series or parallel resonance, depending on the needs. Resonance reduces the internal resistance of circuit elements created by the inductance and capacitance of the components and increases the useful power of the device. To achieve resonance, the AC frequency in the LC circuit (2.11, 2.12) must match the resonant frequency, which depends on the inductance of the inductor coil and the capacitance of the film capacitors. The AC oscillation frequency is set by the PWM duty cycle using the microcontroller (2.9).

An induction heater consisting of an inductor coil (3.3) and a conductor (3.1) is mounted in the upper unit of the device (1.1) using fasteners. An example of the heater design is shown in Fig. 3.

The inductor coil is located next to the LC circuit board (2.11) and connected to its contacts. The inductor coil can be made of copper or aluminum, and the conductor itself can be solid, stranded, or Litz wire—a multi-stranded wire where each strand is insulated from the others.

The coil may be laid in a spiral shape within a guide housing to maintain its shape (3.3). The coil guides may be made of heat-resistant dielectric materials, such as high-temperature polymer resin, clay, or ceramic. The guides may be provided with openings for placing a temperature sensor near the conductor fastening elements (3.1).

A heat-shielding dielectric plate made of ceramic, fluoroplastic, or mica can be placed between the inductor coil guide housing (3.3) and the conductor (3.1), or an air gap of up to 10 mm can be used. The shield is used to reduce heating of the inductor coil and housing (3.3) from heat emanating from the conductor (3.1).

The conductor (3.1) is assembled from a set of plates, ranging from 1 to 10. For example, it can be made from 5 flat round plates with a diameter of 80 mm, each 1 mm thick. Two of the plates can be made of magnetic stainless steel for heating by eddy currents generated by the alternating magnetic field of the inductor (3.3) when an alternating current passes through it. The remaining plates are made of food-grade aluminum and placed under the magnetic stainless steel plates. The ends of the plates and the bottom of the aluminum outlet plate can be coated with Teflon to prevent the hookah smoking mixture from burning upon contact with the conductor. The plates should be cut out in the form of petals, straight rays, or holes to allow air to pass through during purging and to ensure the required level of mixture convection in the hookah bowl. The shape and size of the holes affect the final convection of the system.

Ferrites (3.4) can also be placed in the inductor guides to increase the magnetic field efficiency when using induction heating. The inductor can then be covered with a retaining cap (3.5), which can also accommodate a temperature sensor clamp (2.13). The entire heater can then be stored in a common aluminum housing (3.6) and covered with a stainless steel or aluminum cap (3.7), behind which the LC circuit board (2.11) can be installed.

When installing the heater on the hookah, you must ensure that the bottom plate of the conductor is in contact with the edge of the bowl in which the hookah smoking mixture is placed.

When the inverter circuit is powered by 24 V, the total capacitance of the film capacitors is 4.5 μF and the inductance of the inductor coil is 5 μH, the following operating parameters can be obtained:

Power consumption is approximately 320 watts at maximum heating power and a PWM duty cycle of 48%. Heating from 25°C to 200°C takes 4 minutes 35 seconds, and the hookah reaches its operating temperature in 7 minutes 50 seconds, comparable to using coal. Furthermore, carbon monoxide and ash generated by smoldering coal are completely eliminated from the smoking process. This design ensures high heating speed, low inertia, and reliable operation of the heater, ensuring optimal parameters for stable and high-quality vapor production and the flavor characteristics of the hookah mixture.

Claims (10)

1. An induction heater for hookah mixtures comprising an inductor in the form of a conductive coil and a conductor located within a magnetic field created by the inductor when alternating current passes through it, characterized in that the conductor consists of a set of metal plates laid one on top of the other, wherein the plates are made of magnetic and non-magnetic metals, cutouts are made in the plates for the passage of air at the moment of inhalation of the hookah mixture through the mouthpiece, the plates made of magnetic metal are located in the region of the alternating magnetic field of the inductor and are heated due to the resulting Foucault currents, the plates made of non-magnetic metal are heated through thermal conductivity and radiation from the plates made of magnetic metal, the heated conductor transfers heat to the hookah mixture and the hookah bowl by convection of hot air passing through the holes in the conductor when the user inhales through the mouthpiece, radiation from the heated conductor and thermal conductivity between the conductor and the hookah bowl, as well as between hookah mixture and conductor upon their contact. 2. An induction heater according to paragraph 1, characterized in that the conductor plates may have the shape of a circle or a polygon, while their dimensions may vary: thickness from 0.5 to 8 mm, diameter of the circumscribed circle - from 60 to 90 mm. 3. An induction heater according to paragraph 1, characterized in that the conductor plates can be made of magnetic and non-magnetic metals and alloys, including food-grade aluminum of the AK, AD, A grades and magnetic steels AISI 430, AISI 409, 08X13. 4. An induction heater according to claim 1, characterized in that the number of conductor plates varies from two to ten, and at least one plate is made of magnetic metal. 5. An induction heater according to claim 1, characterized in that the cutouts in the conductor plates are made in the form of petals, notches, round holes or rectangular holes. 6. An induction heater according to paragraph 1, characterized in that the inductor is made in a shape and dimensions corresponding to the dimensions and shape of the conductor plates, and can be made of copper, aluminum or other current-conducting metals and alloys. 7. An induction heater according to paragraph 1, characterized in that the ends of all plates and the plane of the output lower plate of the conductor are coated with a ceramic or Teflon material or by an oxidation method to improve heat transfer and protect against burning of the hookah mixture. 8. An induction heater according to paragraph 1, characterized in that the conductor plates can be provided with mounting holes for fixation. 9. An induction heater according to paragraph 1, characterized in that the conductor plates are located under the inductor and heat is transferred to the hookah mixture from top to bottom. 10. An induction heater according to paragraph 1, characterized in that a heat shield with a thickness of 1 to 7 mm, made of fluoroplastic, mica, ceramics, heat-resistant glass, can be installed between the conductor and the inductor, or an air gap of up to 7 mm can be left.