Patent Description:
Hookahs originated in India and are mainly popular in Arab countries. Referring to <FIG>, a hookah generally includes a hookah bowl <NUM> for containing shredded tobacco <NUM> or tobacco paste, a hookah bottle <NUM> for containing filtered water, and a hookah pipe <NUM> formed at a side wall of the hookah bottle <NUM>. The hookah bowl <NUM> is provided with an air pipe <NUM> at the bottom, and a filtering pipe <NUM> is communicated with the air pipe <NUM> and the filtered water in the hookah bottle <NUM>, respectively. When in use, filtered water <NUM> with a certain amount is filled in the hookah bottle <NUM>, and the hookah bowl <NUM> is then placed on the hookah bottle <NUM>, with the air pipe <NUM> is inserted into the filtering pipe <NUM>. A silicone sealing gasket <NUM> is arranged between the hookah bowl <NUM> and the upper part of the hookah bottle <NUM>. Next, the shredded tobacco <NUM> is placed in the hookah bowl <NUM>, and the opening of the hookah bowl <NUM> is wrapped with a small piece of tin foil where some air holes are poked, and then burning charcoal is placed on the tin foil. A smoking pipe <NUM> is inserted into hookah pipe <NUM> and can be sucked on for smoking the hookah. Specifically, the shredded tobacco <NUM> is heated and burnt due to the burning charcoal, when the smoking pipe <NUM> is sucked on, air enters the hookah bowl <NUM> via the air holes on the tin foil, and then is filtered in the filtered water <NUM>, and finally enters user's mouth.

However, such a traditional hookah heating manner is complicated, and furthermore the temperature of the charcoal is uncontrollable. On the other hand, harmful gas or smokes will be produced due to charcoal burning, which is harmful to human body after inhalation, and also leads to contaminant to the environment or brings fire hazard.

For these issues, Chinese patent <CIT> discloses an electrically heated hookah bowl. A metal tube is directly arranged at the bottom of the hookah bowl, on which a coil is wound. When in use, the coil is energized to heat the metal tube, thereby heating and burning the shredded tobacco. However, it's difficult to clean the hookah bowl with such a structure, to cause smoke stains accumulated in the bowl. Meanwhile, the heating efficiency is low since the heating source is configured at the bottom of the bowl, and it's difficult for the air to uniformly enter the shredded tobacco to lead to bad uniformity of the tobacco burning, especially during the initial smoking.

Chinese patent application <CIT> discloses a hookah electronic charcoal, which uses high thermal conductivity ceramics to replace the hookah charcoal. When in use, on one hand, the air holes in the foil will be blocked, causing it difficult for air to enter the hookah bowl, which limits the smoking amount; on the other hand, the foil is firstly heated through the thermal conductivity, and then the shredded tobacco is heated, which results in a poor heating efficiency. For this, a bulky transformer will possibly be required to enhance the power to increase the heating efficiency. International publication <CIT> discloses a device including a chamber intended for receiving smoking tobacco, means of heating said tobacco, and means for evacuating smoke produced when the tobacco is heated, as well as electricity supply means, which permit the production of an alternating current, as well as induction means suitable for producing an electromagnetic field by the action of the alternating current supplied by the electricity supply means, the induction means being suitable for producing an increase in the temperature of the heating means.

Therefore, there is an urgent need for an improved hookah heating device to solve the above problems.

The purposes of the present invention are to provide an electromagnetic heater for heating hookah and an electromagnetic heating device for hookah, to increase the heating efficiency, the safety and the reliability.

As a first aspect of the present invention, as defined in claim <NUM>, an electromagnetic heater for heating hookah includes a shell and an electromagnetic heating body installed in the shell, the shell includes a heat-insulating base plate, and the electromagnetic heating body includes an excitation coil and a drive circuit, the excitation coil is in a shape of a sheet and formed by spiraling a wire outward from a center, the excitation coil is configured to face the heat-insulating base plate and send out a high-frequency AC signal by which an eddy current effect is produced on an electromagnetic induction element to the heat-insulating base plate, under a control of the drive circuit.

According to the invention, a plurality of support legs for supporting the shell are protruded on the heat-insulating base plate, the support legs are supported on a hookah bowl, and an air inlet is formed between the heat-insulating base plate and the hookah bowl and communicated with the hookah bowl.

Preferably, the support legs are configured near an outer edge of the heat-insulating base plate and distributed around a center of the heat-insulating base plate, and a heating area is defined on the heat-insulating base plate.

Preferably, an outer protruding portion is protruded from a middle of the heat-insulating base plate, and a backside of the outer protruding portion is recessed to accommodate the excitation coil.

Specifically, the outer protruding portion has a horizontal plate lower than ends of the support legs, the support legs are configured near an outer edge of the heat-insulating base plate and distributed around a center of the heat-insulating base plate, and the outer protruding portion is inserted into the hookah bowl when the support legs are supported on the hookah bowl.

More specifically, multiple guide bumps are provided along a periphery of the outer protruding portion, the guide bumps and the support legs are arranged in a staggered manner; a distance between an outer side of each guide bump and a center of the heat-insulating base plate is greater than or equal to that between an inner side of each support leg and the center of the heat-insulating base plate, and is less than that between an outer side of each support leg and the center of the heat-insulating base plate, and an outer end of each guide bump is inclined to form a guide wall.

Preferably, the heater further includes a heat-resistant cover removable from the hookah bowl, wherein an upper surface of the heat-resistant cover is recessed to form an accommodating cavity, a bottom wall of the accommodating cavity is provided with a through hole, a middle of the heat-insulating base plate is provided with an outer protruding portion that is engaged with the accommodating cavity, the shell is movably supported on the heat-resistant cover, the outer protruding portion is inserted into the accommodating cavity, and an air inlet is formed between the heat-resistant cover and the heat-insulating base plate to communicate with external environment and the through hole, respectively.

Preferably, the electromagnetic heating body further comprises a control unit for controlling operations of the drive circuit and a power supply unit for supplying power to the drive circuit; the shell comprises a top shell, a bottom shell, and an isolation cover installed between the top shell and the bottom shell, a first chamber for installing the control unit and the power supply unit is formed between the top shell and the isolation cover, and a second chamber for installing the excitation coil is formed between the isolation cover and the bottom shell, and the first chamber is isolated from the second chamber by the isolation cover; the heat-insulating base plate forms a bottom wall of the top shell, and a middle of the isolation cover is recessed toward the second chamber to form an isolation cavity, a side of the isolation cover opposite to the isolation cavity is provided with an inner protruding portion, and the excitation coil is installed between the inner protruding portion and the heat-insulating base plate.

Preferably, a radial length of a cross section of a wire of the excitation coil is greater than a thickness length in a centerline direction of the wire. In such a way, the energy is saved, and the heating efficiency is high, which facilitates the eddy current induction on the electromagnetic induction element.

As a second aspect of the present invention, as defined in claim <NUM>, an electromagnetic heating device for hookah includes an electromagnetic heater and an electromagnetic induction element, wherein the electromagnetic induction element is installed at a hookah bowl, the electromagnetic heater comprises a shell and an electromagnetic heating body installed in the shell, the shell comprises a heat-insulating base plate, the electromagnetic heater is installed above the hookah bowl, and the heat-insulating base plate is faced against an opening of the hookah bowl; the electromagnetic heating body comprises an excitation coil and a drive circuit, the excitation coil is in a shape of a sheet and formed by spiraling a wire outward from a center, the excitation coil is configured to face the heat-insulating base plate and send out a high-frequency AC signal by which an eddy current effect is produced on the electromagnetic induction element to the heat-insulating base plate, under a control of the drive circuit.

Preferably, the electromagnetic induction element is a tin foil wrapped on a rim of the hookah bowl or a metal sheet installed on the rim of the hookah bowl or an electromagnetic induction sheet disposed in the hookah bowl, the tin foil or the metal sheet has a plurality of air holes, and the electromagnetic induction element is configured to heat tobacco in the hookah bowl to generate smoke.

Preferably, the electromagnetic induction element is installed on a rim of the hookah bowl and provided with a recess for holding tobacco, a plurality of air holes are provided at a bottom of the recess to communicate with the hookah bowl, and the electromagnetic induction element is configured to heat the tobacco in the hookah bowl to generate smoke which enters to the hookah bowl then into a hookah bottle via the air holes.

Preferably, the electromagnetic induction element is movably supported on the opening of the hookah bowl where is provided with a plurality of air holes, the electromagnetic heater is movably arranged on the electromagnetic induction element and provided with a plurality of air inlets to communicate with the external environment and the air holes respectively; and the electromagnetic induction element is configured to heat tobacco in the hookah bowl to generate smoke. In the present invention, the electromagnetic output part (namely the electromagnetic heater) and the electromagnetic induction part (namely the electromagnetic induction part) are two independent parts, which are detachably connected or completely independent. The magnetic induction parts may be removed separately for cleaning, which is convenient for cleaning and easy to replace. Furthermore, the electromagnetic induction element of the present invention is directly movable and supported on the hookah bowl, and there is no need to use additional element such as a sealing cover to seal the hookah bowl, which is convenient to use.

Preferably, the electromagnetic induction elements are tinplate stamping sheets, stainless steel sheets or stainless iron sheets.

Preferably, a periphery of the heat-insulating base plate is provided with a plurality of support legs, and the support legs are supported on a periphery of the electromagnetic induction element, and the air inlets are formed between two adjacent support legs.

Preferably, a peripheral edge of the electromagnetic induction element is supported on a rim of the opening of the hookah bowl to close the opening, a middle of the electromagnetic induction element is recessed downward to form a heating portion which is inserted into the hookah bowl, the air holes are formed on the heating portion; a heating chamber is defined between the heat-insulating base plate and the heating portion, and the air inlets are formed between the heat-insulating base plate and the electromagnetic induction element, one end of the heating chamber is connected to the air inlets, and another end of the heating chamber is connected to the air holes; when smokes, external air enters the heating chamber through the air inlets and is heated by the electromagnetic induction element in the heating chamber and then enters the hookah bowl from the air holes.

In comparison with the prior arts, an electromagnetic heater is proposed for heating tobacco products (shredded tobacco, tobacco paste, etc.). When in use, a tin foil may be wrapped on a hookah bowl in a traditional way as an electromagnetic induction element, or an electromagnetic induction element is supported on or disposed in the hookah bowl, and an electromagnetic heater is configured on the hookah bowl and is energized to the excitation coil to cause the electromagnetic induction element to produce an eddy current effect, so that the electromagnetic induction element is heated up to burn the tobacco products. On the one hand, the electromagnetic induction element is heated by the electromagnetic heater, which has high heating efficiency and requires small power for the power supply. On the other hand, the excitation coil is in the shape of a sheet and is formed by spiraling a wire outward from a center, which promotes an eddy current effect produced on an electromagnetic induction element to heat efficiently. Without additional thermal conductive components. Moreover, the electromagnetic induction element is heated by receiving high-frequency electromagnetic signal from the electromagnetic heater, no additional physical circuit is connected, which greatly improves the stability and reliability of the system.

In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. The same reference numbers in different figures represent the same parts.

Referring to <FIG> and <FIG>, an electromagnetic heating device for hookah of the invention includes an electromagnetic heater <NUM> and an electromagnetic induction element <NUM>. Specifically, the electromagnetic induction element <NUM> is configured to install on a hookah bowl <NUM> of a hookah and contact with tobacco <NUM> (such as tobacco shred or tobacco paste) in the hookah bowl <NUM>. The electromagnetic heater <NUM> includes an excitation coil <NUM> and a drive circuit <NUM> which is configured to drive the excitation coil <NUM> to emit a high-frequency AC signal to produce eddy current effect on the electromagnetic induction element <NUM>.

Referring to <FIG>, the electromagnetic heater <NUM> includes a shell <NUM> and an electromagnetic heating body <NUM> installed in the shell <NUM>. The shell <NUM> includes a heat-insulating base plate <NUM>. The electromagnetic heating body <NUM> includes the excitation coil <NUM> and the drive circuit <NUM>. Specifically, the excitation coil <NUM> is in a sheet form and formed by gradually spiraling a wire outward from a center, in a plane, and an end of the excitation coil <NUM> is extended towards the heat-insulating base plate <NUM>. The excitation coil <NUM> is configured to emit a high-frequency AC signal by which an eddy current effect is produced on the electromagnetic induction element <NUM> to the heat-insulating base plate <NUM>, under a control of the drive circuit <NUM>.

In the present embodiment, the electromagnetic induction element <NUM> is movably placed on the hookah bowl <NUM> of the hookah and contact with the tobacco <NUM> (such as tobacco shred or tobacco paste) in the hookah bowl <NUM>. The electromagnetic heater <NUM> is movably placed on the electromagnetic induction element <NUM>, and at least one air hole <NUM> is formed on the electromagnetic induction element <NUM> where is corresponding to the position of the opening of the hookah bowl <NUM>. As discussed, electromagnetic heater <NUM> includes the excitation coil <NUM> and the drive circuit <NUM>, and the excitation coil <NUM> is configured to emit a high-frequency AC signal by which an eddy current effect is produced on the electromagnetic induction element <NUM> to the heat-insulating base plate <NUM>, under the control of the drive circuit <NUM>. Specifically, terms "movably placed" or "movably supported" in the present disclosure mean that, the object may be movable in the lateral direction and may be picked up in the longitudinal direction directly, without moving the hookah bowl <NUM>.

Referring to <FIG>, when the electromagnetic heater <NUM> is movably placed on the electromagnetic induction element <NUM>, at least one air inlet <NUM> is formed between the electromagnetic heater <NUM> and the electromagnetic induction element <NUM>, and the air inlet <NUM> is communicated with the external environment and the air holes <NUM> respectively. Specifically, a plurality of support legs <NUM> for supporting the shell are protruded on the heat-insulating base plate <NUM>, and the support legs are supported above the hookah bowl <NUM>, and furthermore the air inlet <NUM> is formed between the heat-insulating base plate <NUM> and the hookah bowl <NUM> and communicated with the inside of the hookah bowl <NUM>. The support legs <NUM> may be located at an edge position of the heat-insulating base plate <NUM>, or located at the middle position of the heat-insulating base plate <NUM>, if only the heat-insulating base plate <NUM> is suspended above the hookah bowl <NUM>. The electromagnetic induction element <NUM> is a metal sheet supported above the opening of the hookah bowl <NUM>.

Referring to <FIG>, a distance is formed between the electromagnetic induction element <NUM> and the ventilation pipe <NUM> in the hookah bowl <NUM>. When smoking, the drive circuit <NUM> drives the excitation coil <NUM> to send out a high-frequency AC signal to produce an eddy current effect on the electromagnetic induction element <NUM>, so that the electromagnetic induction element <NUM> heats the tobacco <NUM> to generate smoke accordingly. When smokes, air enters the air holes <NUM> from the air inlet <NUM>,and enters the hookah bowl <NUM>, causing the smoke generated in the hookah bowl <NUM> to enter the smoke ventilation pipe <NUM> and into the filtering pipe <NUM>, the smoke is filtered and then is sucked through the pipes <NUM> and <NUM>.

Referring to <FIG> and <FIG>, in this embodiment, the electromagnetic induction element <NUM> mounted on the hookah bowl <NUM> includes a peripheral edge <NUM> and a heating portion recessed in the middle. Specifically, the peripheral edge <NUM> is supported on the rim of the opening of the hookah bowl <NUM> to prevent the smoke from overflowing. The heating portion <NUM> is recessed, thus the electromagnetic induction element <NUM> is in a cover form to cover the opening of the hookah bowl <NUM>. In this embodiment, the heating portion <NUM> is a circular recess, which may be other shapes.

For example, referring to <FIG>, the heating portion 43a is in a shape of ringed recess. In this case, the heating portion 43a may be reached above or beneath the top of the pipe <NUM>.

In this embodiment, the electromagnetic induction element <NUM> may be formed in an integral structure, that is, the peripheral edge <NUM> and a heating portion <NUM>/43a are made of integral materials. Alternatively, the electromagnetic induction element <NUM> may be formed by different materials, and the heating portion 43a also may be formed by different materials, such as that portion facing against the pipe <NUM> is made of non-magnetic and heat-resistant material, such as ceramic.

Specifically, the electromagnetic induction element <NUM> further includes a handle <NUM> extending from the peripheral edge <NUM>, by which the user can remove the electromagnetic induction element <NUM> from the hookah bowl <NUM> via a clamp for example. Preferably, a hole <NUM> may be provided on the handle <NUM> to hang the removed electromagnetic induction element <NUM>.

In this embodiment, the electromagnetic induction element <NUM> is formed by stamping a metal sheet (e.g., a tinplate sheet, a stainless steel sheet, a stainless iron sheet, etc.), and may also be other electromagnetic induction materials or materials mixed with metal.

Referring to <FIG>, a heating chamber <NUM> is defined between the heat-insulating base plate <NUM> and the heating portion <NUM> of the electromagnetic induction element <NUM>. One end of the heating chamber <NUM> is connected to the air inlet <NUM>, and the other end is connected to the air holes <NUM>. When smokes, the external air enters the heating chamber <NUM> through the air holes <NUM>, and is heated by the electromagnetic induction element <NUM> in the heating chamber <NUM> and then enters the hookah bowl <NUM> from the air holes <NUM>. When the electromagnetic heater <NUM> is disposed on the electromagnetic induction element <NUM> and then energized, the electromagnetic induction element <NUM> will generate eddy current effect to produce heat. Therefore, the air in the heating chamber <NUM> will be heated due to the electromagnetic induction element <NUM>, which improves the smoking experience and maintains a sufficient and stable temperature in the bowl <NUM> because warm air enters to the bowl <NUM>, and meanwhile the combustion of the tobacco <NUM> is stable.

In another embodiment, the periphery <NUM> of the electromagnetic induction element <NUM> may has a lower flange which is bent downward to wrap the periphery of the hookah bowl <NUM>, and the handle <NUM> is formed at the end of the lower flange.

Referring to <FIG>, the support legs <NUM> are distributed around a center of the heat-insulating base plate <NUM>, and a heating area corresponding to a position of the excitation coil <NUM> is formed around the support legs <NUM>. Specifically, the support legs <NUM> are arranged near the peripheral edge of the heat-insulating base plate <NUM>.

Referring to <FIG> and <FIG>, an outer protruding portion <NUM> is protruded from the middle of the heat-insulating base plate <NUM>, and a backside of the outer protruding portion <NUM> is recessed to accommodate the excitation coil <NUM>.

Specifically, the outer protruding portion has a horizontal plane lower than ends of the support legs <NUM>, the support legs <NUM> are configured near an outer edge of the heat-insulating base plate <NUM> and distributed around the center of the heat-insulating base plate <NUM>, and the outer protruding portion <NUM> is extended into the hookah bowl <NUM> when the support legs <NUM> are supported on the hookah bowl <NUM>.

In this embodiment, the support legs <NUM> are supported on the peripheral edge <NUM> of the electromagnetic induction element <NUM>, and the outer protruding portion <NUM> inserts into the recess of the heating portion <NUM> to engage with the heating portion <NUM>. Specifically, the radius of the outer protruding portion <NUM> is smaller than that of the heating portion <NUM>, and the distance from the outer protruding portion <NUM> to the end of the support legs <NUM> is smaller than the depth of the heating portion <NUM>.

Referring to <FIG>, multiple guide bumps <NUM> are provided along a periphery of the outer protruding portion <NUM>, the guide bumps <NUM> and the support legs <NUM> are arranged in a staggered manner; a distance between outer sides of the guide bumps <NUM> and the center of the heat-insulating base plate <NUM> is greater than or equal to that between inner sides of the support legs <NUM> and the center of the heat-insulating base plate <NUM>, and is less than that between outer sides of the support legs <NUM> and the center of the heat-insulating base plate <NUM>, and an outer end of each guide bump <NUM> is inclined to form a guide wall (as shown in <FIG>, the guide wall is used for guiding the outer protruding portion <NUM> into the pitch of the heating portion <NUM>).

Specifically, a guide channel is formed between adjacent guide bumps <NUM>, and extended along the centerline direction (longitudinal direction) of the hookah bowl <NUM>. The heating cavity <NUM> is formed between the outer protruding portion <NUM> and the heating portion <NUM>, and multiple guide channels are located above the outer side of the heating chamber <NUM>. In such a way, the air needs to descend from the air inlet for a period of time to enter the heating chamber <NUM> horizontally. The air inlet <NUM> is located above the outside of the heating chamber <NUM>, and the guide channels are extends from top to bottom. In the present embodiment, the guide channels are longitudinal channels from top to bottom, and do not extend axially on the outer protruding portion <NUM>. In other embodiments, the guide channels may be spiral channels spiraling outside the outer protruding portion.

In this embodiment, the bottom of the heating portion <NUM> of the electromagnetic induction element <NUM> is a flat sheet parallel to the opening of the hookah bowl <NUM>, and the position of the bottom shell <NUM> opposite to the heating portion <NUM> is flat, so that the heating chamber <NUM> is flat. Of course, the bottom of the heating portion <NUM> of the electromagnetic induction element <NUM> may be in the shape of a cone, a downwardly inclined triangle, a cone, or a sphere, etc., which is not limited.

Preferably, the electromagnetic heating body <NUM> further includes a control unit <NUM> for controlling operations of the drive circuit <NUM> and a power supply unit for supplying power to the drive circuit <NUM>.

Referring to <FIG>, a circuit block diagram of the electromagnetic heating body <NUM> of the present invention is shown. As illustrated, the power supply unit includes a storage battery <NUM>, a charging management unit <NUM>, a power management unit <NUM>, and a DC interface <NUM>. Specifically, the DC interface <NUM> is connected to the storage battery <NUM> through the charging management unit <NUM>, and the charging management unit <NUM> is configured to manage the charging and discharging of the storage battery <NUM>. The power management unit <NUM> is configured to convert the electrical energy in the storage battery into a corresponding voltage and send it to the drive circuit <NUM> to supply power.

More specifically, the power supply unit also includes an auxiliary power supply <NUM> connected to the power management unit <NUM> through a power supply interface <NUM>, by which the external commercial power is converted into a power supply voltage and sent to the power supply management unit <NUM>. The power management unit <NUM> is configured to convert the power supply voltage into a working power supply voltage for driving the drive circuit <NUM>.

More specifically, the DC interface <NUM> is further connected to the power management unit <NUM> which is configured to convert the electrical energy input from the DC interface <NUM> into a working voltage and send it to the drive circuit <NUM>. The DC interface <NUM> may be a DC power supply interface such as a standard USB interface, a micro USB interface, or a type-c interface. In this embodiment, the storage battery <NUM> is a lithium battery.

Three power input modes such as auxiliary power supply, DC interface power supply, and battery power supply are included in the present embodiment. The control unit <NUM> is connected to the power management unit <NUM> to control the power management unit <NUM> to select the power input mode according to the priority, and the priority from high to low is auxiliary power supply, DC interface power supply, and battery power supply. The power management unit <NUM> is configured to design different topologies according to different input voltages, such as a pass-through mode, a boost mode, a buck mode, and a buck-boost mode.

Referring to <FIG>, a circuit schematic diagram of the electromagnetic heating body <NUM> is shown, which includes three power inputs provided by the power supply unit: an auxiliary power supply VDC, a DC interface power supply VUSB and a battery power supply VBAT. The power management unit <NUM> converts the electric energy input by different power input methods into the voltage required by the drive circuit <NUM>, and the drive circuit <NUM> controls the LC network to output the corresponding high-frequency AC signal under the control of the control unit <NUM>. Specially, the LC network includes a resonant capacitor and a resonant inductor (excitation coil <NUM>) that are in series, and the LC network is configured to send a high-frequency AC signal to the electromagnetic induction element <NUM> to generate an eddy current effect on the element <NUM>, thereby generating heat. Additionally, the electromagnetic heating body <NUM> has a voltage detection circuit <NUM> and a current detection circuit <NUM> for collecting the voltage across the LC network and the current on the excitation coil <NUM> respectively, which are then transmitted to the control unit <NUM>.

When the high-frequency AC signal is sent to the electromagnetic induction element <NUM>, an induced current is generated on the electromagnetic induction element <NUM>. In this disclosure, the resistivity of the electromagnetic induction element <NUM> changes with the temperature, specifically, the resistivity of the electromagnetic induction element <NUM> has a linear change with temperature within a normal temperature range, and the change relationship is expressed as ρ = ρ<NUM>(<NUM>+αt), where ρ and ρ0 represent a resistivity at the current temperature t°C and <NUM>, respectively; α represents a temperature coefficient of the resistivity of the electromagnetic induction element <NUM>, and t represents a temperature value of the electromagnetic induction element. That is to say, the change of the resistance of the electromagnetic induction element <NUM> has a linear relationship with the change of the temperature, expressed as t = (R - R<NUM>) / (R<NUM> * α), where R and R0 represent resistance values at the current temperature t°C and <NUM>, respectively, and α represents a temperature coefficient of the resistivity of the electromagnetic induction element <NUM>. According to the formula, it can be concluded that, when the temperature rises, the resistance of the electromagnetic induction element <NUM> will increase accordingly; thus, the loop current of the LC network is will also decrease, and the power fed back to the drive circuit <NUM> will decrease accordingly. That is to say, the power of the drive circuit where the LC network is located is also reduced, and as known that power has a linear relationship with the temperature of the electromagnetic induction element <NUM>. According to the power calculation formula P=UI, it is obtained that the temperature of the electromagnetic induction element <NUM> can be calculated as long as the power of the drive circuit is calculated. In the memory of the control unit <NUM>, current values, voltage values, power values, temperature coefficients, preset temperature, etc. of the drive circuit are stored. After the entire system starts to work, the control unit <NUM> obtains the current and voltage in the drive circuit detected by the voltage detection circuit <NUM> and the current detection circuit <NUM> and calculates the power of the drive circuit, and then calculates the temperature of the electromagnetic induction element <NUM> according to the temperature coefficients. Once the temperature is greater than the preset temperature, and the control unit <NUM> controls the drive circuit <NUM> to stop outputting the control signal to the LC network, and the electromagnetic induction element <NUM> stops heating. When the temperature of the electromagnetic induction element <NUM> is lower than the preset temperature, the drive circuit <NUM> continues to output a control signal to the LC network, and the electromagnetic induction element <NUM> continues to heat, thereby performing the temperature control.

Preferably, during the temperature control process, the detected temperature of the electromagnetic induction element <NUM> is integrated in real time. An upper limit and a lower limit of the temperature integration are pre-determined. A smoking behavior will be determined to happen once the temperature integration rapidly exceeds the upper limit, then the number of puffs is started to count.

Specifically, the control unit <NUM> includes an MCU, a switch button <NUM> and a detection circuit. A start command can be input by pressing the switch button <NUM>, and the MCU is started upon commands to control the operation of the drive circuit <NUM>. Of course, the MCU is also configured to detect an existence of an electromagnetic induction element through the detection circuit. If yes, the MCU is started; otherwise, the MCU enters a standby state. The detection circuit includes a voltage detection circuit <NUM> and a current detection circuit <NUM>, and the MCU can determine the existence of the electromagnetic induction element via the voltage and current collected by the voltage detection circuit <NUM> and the current detection circuit <NUM>. The MCU, the switch button <NUM>, the detection circuit and the drive circuit <NUM> are all mounted on the circuit board <NUM>.

Referring to <FIG>, in one embodiment, the drive circuit <NUM> is a full-bridge drive circuit, which can greatly improve the work efficiency and save energy.

The drive circuit <NUM> consists of a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3, and a MOS transistor Q4, and forms a main circuit of a high-frequency signal generating circuit with the LC network. The LC network consists of a resonant capacitor C1 and a resonant inductor L1. The resonant inductance L1 is an equivalent inductance of the excitation coil <NUM>, and R is the equivalent resistance of the electromagnetic induction element <NUM>, which is used to receive the high-frequency AC signal sent by the inductance L1 to generate heat. Specifically, the LC network is a series resonant network, and the resonant frequency is: <MAT>. When the control unit <NUM> controls the drive circuit <NUM> to cause the frequency of the driving signal f=f0, resonance will be generated on the circuit. The time sequence follows: for positive half-cycle, the current flows as below: VCC->Q1->C1->L1->Q4->GND; for negative-half cycle, the current flows as below: VCC->Q2->L1->C1->Q3 -> GND.

Referring to <FIG>, in another embodiment, the drive circuit <NUM> may be a half-bridge drive circuit.

Specifically, the drive circuit <NUM> consists of a MOS transistor Q5 and a MOS transistor Q6, and forms a main circuit of a high-frequency signal generating circuit with the LC network. The LC network consists of a resonant capacitor C1 and a resonant inductor L1. The resonant inductance L1 is an equivalent inductance of the excitation coil <NUM>, and R is the equivalent resistance of the electromagnetic induction element <NUM>, which is used to receive the high-frequency AC signal sent by the inductance L1 to generate heat. Specifically, the LC network is a series resonant network, and the resonant frequency is: <MAT>. When the control unit <NUM> controls the drive circuit <NUM> to cause the frequency of the driving signal f=f0, resonance will be generated on the circuit. The time sequence follows: for positive half-cycle, the current flows as below: VCC -> Q1->C1->L1->GND; for negative half-cycle, the current flows as below: L1 ->C1->L1->Q2->GND.

Referring to <FIG>, in one more embodiment, the drive circuit <NUM> is an amplifier circuit of Class E.

Specifically, the drive circuit consists of MOS transistor Q7, a capacitor C2 and a high-frequency choke coil L0, and forms a main circuit of a high-frequency signal generating circuit with a LC network. The LC network consists of a resonant capacitor C1 and a resonant inductor L1. The resonant inductance L1 is an equivalent inductance of the excitation coil <NUM>, and R is the equivalent resistance of the electromagnetic induction element <NUM>, which is used to receive the high-frequency AC signal sent by the inductance L1 to generate heat. Specifically, the LC network is a series resonant network, and the resonant frequency is: <MAT>. When the control unit <NUM> controls the drive circuit <NUM> to cause the frequency of the driving signal f=f0, resonance will be generated on the circuit.

Referring to <FIG> and <FIG>, the shell <NUM> includes a top shell <NUM>, a bottom shell <NUM>, and an isolation cover <NUM> installed between the top shell <NUM> and the bottom shell <NUM>, a first chamber <NUM> for installing the control unit <NUM> and the power supply unit is formed between the top shell <NUM> and the isolation cover <NUM>, and a second chamber <NUM> for installing the excitation coil <NUM> is formed between the isolation cover <NUM> and the bottom shell <NUM>, and the first chamber <NUM> is isolated from the second chamber <NUM> by the isolation cover <NUM>, and the bottom wall of the bottom shell <NUM> is formed from a part of the heat-insulating base plate <NUM>. Due to the isolation cover <NUM>, the control power supply part and the electromagnetic generating part (namely the excitation coil <NUM>) of the electromagnetic heating body <NUM> can be effectively isolated, thereby reducing the thermal influence and electromagnetic influence between the control power supply part and the electromagnetic generating part (excitation coil <NUM>).

Referring to <FIG> and <FIG>, the middle of the isolation cover <NUM> is recessed toward the second chamber <NUM> to form an isolation chamber <NUM>, different from the first chamber <NUM>, the isolation cover <NUM> is provided with an inner protruding portion <NUM> at a backside of the isolation cavity <NUM>, and the excitation coil <NUM> is installed between the inner protruding portion <NUM> and the heat-insulating base plate <NUM>.

Referring to <FIG>, the exciting coil <NUM> is installed on the inner protruding portion, with a space is formed between the exciting coil <NUM> and the heat-insulating base plate <NUM>.

In this embodiment, the edge of the isolation cover <NUM> is provided with several installation positions by which the isolation cover <NUM> is installed on the top shell <NUM>. The top shell <NUM> is assembled with the bottom shell <NUM> by installation components. During the assembly, the control unit <NUM> and the power supply unit are firstly installed in the top shell <NUM>, and then the isolation cover <NUM> is installed on the top shell <NUM> to close the first chamber <NUM>, and then the excitation coil <NUM> is mounted on the inner protruding portion <NUM> of the isolation cover <NUM>, and finally the bottom shell <NUM> is mounted on the top shell <NUM> to close the second chamber <NUM>.

Referring to <FIG> and <FIG>, the bottom shell <NUM> includes a ring-shaped fixing frame <NUM> and the heat-insulating base plate <NUM> engaged with the ring-shaped fixing frame <NUM>. Referring to <FIG>, the heat-insulating base plate <NUM> is made of ceramic. Of course, the heat-insulating base plate <NUM> can be made of other non-magnetic and non-metal heat insulating materials, such as mica.

In this embodiment, the heat-insulating base plate <NUM> is made of the same material as an integral structure. In one embodiment, those parts of the heat-insulating base plate <NUM> contacting with the element <NUM>, namely the support legs <NUM> are made of high-temperature resistant materials, other parts of the heat-insulating base plate <NUM> have lower requirements for high temperature resistance.

Referring to <FIG>, a handle <NUM> for holding is formed on the shell <NUM>.

Referring to <FIG> and <FIG>, an electromagnetic shielding sheet <NUM> is provided on a side of the excitation coil <NUM> away from the heat-insulating base plate <NUM>, and the excitation coil <NUM> is mounted on the electromagnetic shielding sheet <NUM>. Due to the electromagnetic shielding sheet <NUM>, the control power supply in the first chamber <NUM> will not be affected by the electromagnetic field of the excitation coil <NUM>. Specifically, the electromagnetic shielding sheet <NUM> can be made of a material with high magnetic permeability, in order to shield the eddy current phenomenon generated by other metal parts.

Referring to <FIG>, the electromagnetic shielding sheet <NUM> is provided with a groove <NUM> formed from the edge to the center thereof, a first end of the excitation coil <NUM> is spiraled from the edge to the center, then extended along the groove <NUM> to lead out a second end.

As shown in <FIG>, a radial length of the cross section of the wire <NUM> of the excitation coil <NUM> (namely the length in the width direction) is greater than a thickness length in the centerline direction of the wire <NUM>(namely the length in the thickness direction), and the thickness surface of the wire <NUM> is opposite to the heat-insulating base plate <NUM>.

Preferably, referring to <FIG>, the wire <NUM> of the excitation coil <NUM> is flat (the cross section can be rectangular, oval, etc.), and its flat surface is opposite to the heat insulating base plate <NUM>. Alternatively, the cross section of the wire <NUM> of the excitation coil <NUM> may also be triangle, trapezoid, circular or square. The wire <NUM> of the excitation coil <NUM> may be one or more conductors wrapped with an insulating layer.

In the above-mentioned embodiments, the heat-insulating base plate <NUM> of the electromagnetic heater <NUM> is indirectly supported on the hookah bowl <NUM> through the electromagnetic induction element <NUM>, and the heat-insulating base plate <NUM> is engaged with the electromagnetic induction element <NUM> in a concave-convex matching to limit the position in the radial direction to prevent disengagement.

In the above-mentioned embodiments, the electromagnetic induction element <NUM> is covered on the hookah bowl <NUM>, and the hookah bowl <NUM> is communicated with the air of the external environment via the air holes <NUM>.

Specifically, the electromagnetic heater <NUM> is movably supported on the electromagnetic induction element <NUM>. Different from the above embodiments, the electromagnetic induction element <NUM> may be directly and detachably connected to the electromagnetic heater <NUM>, in an engagement manner or screw connection manner.

In the above embodiment, a distance is formed between the heat-insulating base plate <NUM> of the electromagnetic heater <NUM> and the heating portion <NUM> of the electromagnetic induction element <NUM> to define a flat heating cavity <NUM>. Different from the above embodiments, the element <NUM> and/or the bottom of the heat-insulating base plate <NUM> is provided with one or more channels (not shown) connected to the air holes <NUM>. One end of a channel is connected to the air inlet <NUM>, and the other end is connected to one or more air holes <NUM>. In such a manner, the air inlet <NUM> is communicated with the air holes <NUM> via the channels, without a heating cavity.

Referring to <FIG>, different from the above-mentioned embodiments, the electromagnetic induction element <NUM> in the second embodiment is a tin foil wrapped on the rim of the hookah bowl <NUM>, with multiple air holes are formed on the tin foil. The heat-insulating base plate <NUM> of the electromagnetic heater <NUM> is directly supported on the rim of the opening of the hookah bowl <NUM>, and the outer protruding portion <NUM> of the heat-insulating base plate <NUM> is matched with the rim of the opening of the hookah bowl <NUM> (specifically the guide bumps <NUM> are pressed against the inner rim of the hookah bowl <NUM>), to prevent the heat-insulating base plate <NUM> sliding out of the hookah bowl <NUM> in the radial direction.

Referring to <FIG>, different from the above-mentioned embodiments, the electromagnetic heater in the third embodiment further includes a heat-resistant cover <NUM> removable from the hookah bowl <NUM>. An upper surface of the heat-resistant cover <NUM> is recessed to form an accommodating cavity <NUM>, a bottom wall of the accommodating cavity <NUM> is provided with a through hole <NUM>, a center of the heat-insulating base plate <NUM> is provided with an outer protruding portion <NUM> that is matched with the accommodating cavity <NUM>, the shell <NUM> is movably supported on the heat-resistant cover <NUM>, the outer protruding portion <NUM> is extended into the accommodating cavity <NUM>, and an air inlet is formed between the heat-resistant cover <NUM> and the heat-insulating base plate <NUM> to communicate with external environment, and the air inlet is communicates with the through hole <NUM>.

In this embodiment, the heat-resistant cover <NUM> is made of ceramic, and also can be made of other non-magnetically insulating and non-metallic materials, as long as it has good heat-resisting performance.

In this embodiment, the heat-insulating base plate <NUM> is movably supported on the heat-resistant cover <NUM>. In another embodiment, the heat-insulating base plate <NUM> may be connected to the heat-resistant cover <NUM> via fixed connection, engagement connection or other connections. Preferably, the heat-resistant cover <NUM> is provided with a channel formed from the edge to the center to communicate with the air hole <NUM> and the air inlet, respectively.

In other embodiments, the heat-insulating base plate <NUM> may be in a form of a cover to directly support and cover the hookah bowl <NUM>, and an air passage communicating with the outside is opened at a corresponding position of the hookah bowl <NUM>.

In other embodiments, the depth of the accommodating cavity <NUM> of the heat-resistant cover <NUM> is greater than the distance from the support legs <NUM> to the outer protruding portion <NUM>, so that a thermal insulation chamber can be formed between the outer protruding portion <NUM> and the accommodating cavity <NUM> when the heat-insulating base plate <NUM> is supported on the heat-resistant cover <NUM>.

In the present embodiment of <FIG>, the electromagnetic induction element 40b is a metal sheet or metal ring freely placed in the hookah bowl <NUM>, which is a disposable appliance or a non-long-term appliance that can be used several times.

Optionally, the electromagnetic induction element 40b may be provided with several holes to facilitate the tobacco product burning, when the electromagnetic induction element 40b has large area.

Referring to <FIG>, different from the above embodiments, the electromagnetic induction element 40b in the fourth embodiment is installed on the rim of the hookah bowl <NUM> and provided with a recess 43b for holding tobacco <NUM>, and an air hole <NUM> is provided at a bottom of the recess 43b to communicate with the inside of the hookah bowl <NUM>. Air enters the recess 43b to facilitate the burning of the tobacco <NUM>, and then the smoke enters the hookah bowl <NUM> via the air holes <NUM> to enter the hookah <NUM> via the ventilation pipe <NUM>.

Specifically, a space is formed between the electromagnetic induction element 40b and the ventilation pipe <NUM> in the hookah bowl <NUM>. The recess 43b is also served as a heating portion 43b of the electromagnetic induction element 40b.

Preferably, the heat-insulating base plate <NUM> of the electromagnetic heater <NUM> is supported on the electromagnetic induction element 40b, and air inlets are formed between the electromagnetic induction elemen40b and the outside (namely between the adjacent support legs <NUM>), and the air inlets are also communicated with the recess 43b. The heating portion 43b is matched with the outer protruding portion <NUM>.

In order to prevent the smoke from overflowing, the heat-insulating base plate <NUM> of the electromagnetic heater <NUM> is supported on the electromagnetic induction element 40b and also covers the recess 43b.

Referring to <FIG>, different from the above embodiments, the electromagnetic induction element 40c in the fifth embodiment is provided with a recess 43c for holding tobacco <NUM>, the recess 43c is a ring shape, and an air hole <NUM> is provided at a bottom of the recess 43c to communicate with the inside of the hookah bowl <NUM>. Air enters the recess 43c to facilitate the burning of the tobacco <NUM>, and then the smoke enters the hookah bowl <NUM> via the air holes <NUM> to enter the hookah <NUM> via the ventilation pipe <NUM>.

Specifically, a space is formed between the electromagnetic induction element 40c and the ventilation pipe <NUM> in the hookah bowl <NUM>. The recess 43b is also served as a heating portion of the electromagnetic induction element 40c.

Preferably, the heat-insulating base plate <NUM> of the electromagnetic heater <NUM> is supported on the electromagnetic induction element 40c, and air inlets are formed between the electromagnetic induction element 40c and the outside (namely between the adjacent support legs <NUM>), and the air inlets are also communicated with the recess 43c.

In order to prevent the smoke from overflowing, the heat-insulating base plate <NUM> of the electromagnetic heater <NUM> is supported on the electromagnetic induction element 40c and further covers the recess 43c.

Preferably, the electromagnetic induction element 40c may be formed in an integral structure, that is, the peripheral edge and the heating portion 43c are made of integral materials. Alternatively, the electromagnetic induction element 40c may be formed by different materials, and the heating portion 43c also may be formed by different materials, such as that portion facing against the pipe <NUM> is made of non-magnetic and heat-resistant material, such as ceramic.

Alternatively, the electromagnetic heater <NUM> in the first embodiment can be directly supported on the hookah bowl <NUM>, and the electromagnetic induction element <NUM> can be freely placed inside the hookah bowl <NUM>, so that the electromagnetic induction element <NUM> can be heated by the electromagnetic heater <NUM>. Further, the heat-insulating base plate <NUM> of the electromagnetic heater <NUM> covers on the hookah bowl <NUM>, and at least one air inlet <NUM> is formed therebetween.

Claim 1:
An electromagnetic heater (<NUM>) for heating I a hookah, comprising a shell (<NUM>) and an electromagnetic heating body (<NUM>) installed in the shell (<NUM>), the shell (<NUM>) comprising a heat-insulating base plate (<NUM>), and the electromagnetic heating body (<NUM>) comprising an excitation coil (<NUM>) and a drive circuit (<NUM>) the excitation coil (<NUM>) being in a shape of a sheet (<NUM>) and formed by spiraling a wire (<NUM>) outward from a center, the excitation coil (<NUM>) being configured to face the heat-insulating base plate (<NUM>) and send out a high-frequency AC signal by which an eddy current effect is produced on an electromagnetic induction element (<NUM>) adjacent to the heat-insulating base plate (<NUM>), under a control of the drive circuit (<NUM>);
characterized in that, a plurality of support legs (<NUM>) for supporting the shell (<NUM>) are protruded on the heat-insulating base plate (<NUM>), the support legs (<NUM>) are configured to be supported on a hookah bowl (<NUM>), and an air inlet (<NUM>) is formed between the heat-insulating base plate (<NUM>) and the hookah bowl (<NUM>) and communicated with the hookah bowl (<NUM>).