High-frequency heating device

1. A hookah comprising a heating device, a heating cup for accommodating tobacco material, and a smoke filter; the heating device comprising a housing, a thermal insulation cup, a first thermal insulator, a second thermal insulator, and a magnetic induction coil; wherein:

the housing has an L shape in a cross section, and comprises a first arm, and a second arm;

the first arm comprises a first cavity, and the second arm comprises a second cavity;

the magnetic induction coil and the heating cup are disposed in the first cavity;

the thermal insulation cup is sleeved on the heating cup, and is disposed between the magnetic induction coil and the heating cup;

each of the first thermal insulator and the second thermal insulator comprises an annular surface;

the first thermal insulator and the second thermal insulator are disposed on two ends of the thermal insulation cup, respectively;

the heating cup comprises glass and a metal conductor inlaid in the glass; and

the smoke filter is directly connected with the heating cup.

2. The hookah of claim 1 , wherein the heating device further comprises a variable-frequency power source and a battery; wherein the variable-frequency power source and the battery are disposed in the second cavity; the battery comprises an output end soldered on an input end of the variable-frequency power source; an output end of the variable-frequency power source is soldered on the magnetic induction coil; in a power on state, the variable-frequency power source outputs an alternating current and thus the magnetic induction coil produces an induced magnetic field.

3. The hookah of claim 2 , wherein the heating device further comprises a temperature difference sensor, wherein the temperature difference sensor is soldered on the variable-frequency power source and is in the vicinity of a top opening of the thermal insulation cup to sense a temperature of an airflow entering the thermal insulation cup, thus controlling the variable-frequency power source whether or not to enter an automatic heating mode.

4. The hookah of claim 3 , wherein the heating device further comprises a thermistor, wherein the thermistor is soldered on the variable-frequency power source and is located in the thermal insulation cup for over-temperature protection; when a working temperature of the heating device reaches 600 degrees Fahrenheit, no current is output from the variable-frequency power source, and the heating device stops working.

5. The hookah of claim 3 , wherein the heating cup comprises a top end provided with an air inlet through which air enters the heating cup.

6. The hookah of claim 5 , wherein in the power on state, an eddy current is produced in the metal conductor in an induction magnetic field of the magnetic induction coil whereby the metal conductor is heated up, and then the heat is transferred to the heating cup through heat transfer to heat the tobacco material in the heating cup to produce smoke; in a smoking process, the air enters the heating cup via the air inlet, and the temperature difference sensor senses a temperature change in the heating cup and controls the variable-frequency power source to work in an automatic heating mode; the smoke produced in the heating cup is driven by the air to enter the smoke filter where the smoke is filtered by water and then flows out of an exit of the smoke filter for user's inhaling.