Patent Publication Number: US-2022225687-A1

Title: Tobacco evaporator and heating control method

Description:
TECHNICAL FIELD 
     The present application relates to the technical field of electronic smoking devices, in particular to a tobacco evaporator and a heating control method. 
     BACKGROUND 
     At present, there are three ways for tobacco evaporators to heat the substances to be evaporated (such as cut tobacco, cigarette rolls, etc.): the first way is that the smoke bowl adopts thermal conductive materials, wraps a layer of metal heating sheet around the outer wall of the smoke bowl, and transmits the heat to the cut tobacco in the smoke bowl through conduction, so as to achieve the purpose of evaporating the effective components of cut tobacco; the second way is that the smoke bowl is made of ceramic material, a layer of conductive film is printed on the inner or inner wall of the ceramic bowl, and the heat generated after power on is transmitted to cut tobacco through ceramics; the third method belongs to air heating technology, which uses hot air to heat cut tobacco, and the air flow will evenly pass through the cut tobacco in the whole smoke bowl. 
     Among them, the advantage of the second method over the external electric heating film method (i.e. the first method) is that the external electric heating film method is generally made of aluminum or stainless steel to ensure the efficiency of heat conduction; at the same time, because the metal has conductivity, it is generally necessary to wrap a layer of insulating material with high temperature resistance on the metal bowl when wrapping the electric heating film; in this way, although insulation is realized, the efficiency of heat conduction is also weakened. The first method also has the problem of affecting the consistency of product heating speed due to the difference of wrapping tightness of electrothermal film. However, both the first method and the second method adopt the direct heat conduction method. There is a problem of uneven heating in baking cut tobacco, and the baked smoke tastes irritating. For this, the smoke baked by the third method has a soft taste and uniform baking, which is enough to overcome the above defects. Although the problems of taste and uniformity have been improved, the cleaning problem after users use is still a big problem to improve the product experience. Therefore, how to clean the tobacco evaporator used by users has become an urgent problem to be solved in the tobacco industry. 
     SUMMARY 
     By providing a tobacco evaporator, the application solves the technical problem of difficult cleaning of the used tobacco evaporator in the prior art, and realizes the technical effect of convenient and fast cleaning of the tobacco evaporator, keeping the air flow channel clean and the flue gas clean. 
     The embodiment of the present application provides a tobacco evaporator, comprising a body, a smoke circulation channel vertically communicated along the body, and a heating core assembly disposed on the path of the smoke circulation channel, wherein, the heating core assembly comprises a smoke bowl assembly and a preheating assembly connected to the smoke bowl assembly; the smoke bowl assembly comprises a first bowl body and a second bowl body, and the first bowl body and the second bowl body are of an up-down structure or an inner and outer sleeving structure; the second bowl body is elastically fastened to the preheating assembly, and the preheating assembly is used for when cleaning is needed, being detachably taken out of the second bowl body to clean the smoke circulation channel and pushing the preheating assembly into the fastening position in a set direction after cleaning is completed. 
     Preferably, the first bowl body is used for accommodating a substance to be evaporated, the second bowl body is used for accommodating the preheating assembly; the heating core assembly further comprises a clamping portion transversely arranged in the second bowl body, the preheating assembly is elastically fastened to the second bowl body through the clamping portion. 
     Preferably, the tobacco evaporator further comprises a suction nozzle arranged at one end of the body and a vent pipe arranged at another end of the body, the first bowl body and the second bowl body are in an integrated structure; the second bowl body extends with a reduced diameter in a direction away from the first bowl body and abuts against the vent pipe, the clamping portion is transversely arranged in the second bowl body, penetrates the preheating assembly, and abuts against the second bowl body to make the preheating assembly elastically fastened to the second bowl body; when cleaning is needed, the preheating assembly is detachably taken out of the second bowl body and is pushed into the fastening position after cleaning is completed. 
     Preferably, both ends of the clamping portion are provided with elastically stretchable bosses, the preheating assembly is provided with two first openings near an inner diameter of the second bowl body with an abrupt change, the second bowl body is provided with two first grooves at a position corresponding to the two first openings; the elastically stretchable bosses on both ends of the clamping portion penetrate the first opening, and is inserted into the second bowl body, and abuts against a side wall of the first groove to make the preheating assembly elastically fastened to the second bowl body. 
     Preferably, the tobacco evaporator further comprises a suction nozzle arranged on one end of the body, a vent pipe and a support tube arranged on the other end of the body, the first bowl body an d the second bowl body are in an integrated structure; the second bowl body extends with a reduced diameter in a direction away from the first bowl body; one end of the support tube abuts against the body, the other end of the support tube extends to the second bowl body and abuts against a bottom of the second bowl body; one end of the vent pipe abuts against the body, the other end of the vent pipe extends to the preheating assembly and is fixedly connected with a bottom of the preheating assembly; the clamping portion is transversely arranged in the second bowl body, penetrates the preheating assembly, and abuts against the second bowl body to make the preheating assembly elastically fastened to the second bowl body; when cleaning is needed, the preheating assembly is taken out of the second bowl body and is pushed into the fastening position after cleaning is completed. 
     Preferably, both ends of the clamping portion are provided with elastically stretchable bosses, the preheating assembly is provided with two second openings near an inner diameter of the second bowl body with an abrupt change, the second bowl body is provided with two second grooves at a position corresponding to the two second openings; the elastically stretchable bosses on both ends of the clamping portion penetrate the second opening, and is inserted into the second bowl body, and abuts against a side wall of the second groove to make the preheating assembly elastically fastened to the second bowl body. 
     Preferably, the tobacco evaporator further comprises a suction nozzle arranged at one end of the body and a vent pipe arranged at another end of the body, the second bowl body is sleeved on an outer periphery of the first bowl body; the first bowl body is elastically fastened with the second bowl body, the first bowl body is used for accommodating a substance to be evaporated and the preheating assembly; the heating core assembly comprises a clamping portion transversely arranged in the second bowl body, the preheating assembly is elastically fastened with second bowl body through the clamping portion; the clamping portion penetrates and accommodates the preheating assembly and the first bowl body, and abuts against the second bowl body; when cleaning is needed, the preheating assembly is taken out of the second bowl body and is pushed into the fastening position after cleaning is completed. 
     Preferably, both ends of the clamping portion are provided with elastically stretchable bosses, the first bowl body is provided with two fifth openings, the second bowl body is provided with two third grooves at a position corresponding to the two fifth openings; the elastically stretchable bosses on both ends of the clamping portion penetrate the fifth opening, and is inserted into a side wall of the second bowl body, and abuts against a side wall of the third groove to make the preheating assembly elastically fastened to the second bowl body. 
     Preferably, the tobacco evaporator further comprises a flip cover rotatably connected to the body, a rotating shaft is arranged on a bottom of the body, and one end of the flip cover is provided with a hole matched with a clearance of the rotating shaft, so that the flip cover can be turned along the rotating shaft. 
     Preferably, the preheating assembly comprises a preheating assembly housing, thermal conductive materials placed inside the preheating assembly housing and a heating element sleeved outside the second bowl body, an outer wall of the preheating assembly housing is contacted with an inner wall of the second bowl body; the heating element contacted with an outer wall of the second bowl body is used for heating the thermal conductive materials. 
     Preferably, the preheating assembly comprises a preheating assembly housing, a spiral part placed under the preheating assembly housing and abutted against the preheating assembly housing, and a heating element sleeved outside the second bowl body; an outer wall of the spiral part is contacted with an inner wall of the second bowl body; the heating element contacted with an outer wall of the second bowl body is used for heating cold air; the outer wall of the spiral part and the inner wall of the second bowl body form a spiral preheating channel through which the cold air passes to realize the uniform heating of the cold air. 
     Preferably, the tobacco evaporator further comprises a heat insulation for insulating the preheating assembly when the heating element generates heat, the heat insulation comprises an insulation ring sleeved at an upper end of the first bowl body, an insulation sleeve arranged outside the second bowl body and a sealing silica gel connecting the insulation ring and the insulation sleeve; one end of the insulation sleeve is connected with the sealing silica gel, the other end of the insulation sleeve is bent to the vent pipe; the heat insulation forms a closed thermal insulation space with the smoke bowl assembly and the vent pipe, and the thermal insulation space is filled with thermal insulation materials to insulate the tobacco evaporator. 
     On the other hand, the present application provides A tobacco heating control method, wherein, comprises the following steps: 
     S1. a preheating assembly arranged inside a second bowl body and elastically fastened to the second bowl body heating cold air coming into the second bowl body; 
     S2. the heated cold air entering a first bowl body, heating the substance to be evaporated placed in the first bowl body, and evaporating effective components in the substance to be evaporated; 
     S3. when cleaning is needed, the preheating assembly is taken out of the second bowl body and is pushed into a fastening position after cleaning is completed. 
     One or more technical solutions provided in the embodiment of the application have at least the following technical effects or advantages: by designing the air preheating assembly as a detachable component, the user can disassemble the preheating assembly for cleaning; after the preheating assembly is removed from the body, the whole air passage forms a hollow passage through the front and back, without cleaning dead corner, which is convenient for cleaning; at the same time, as a detachable part, the preheating assembly can be replaced with a new one when it is used for a long time, so as to keep the air flow channel clean and the flue gas clean. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       In order to more clearly explain the embodiment of the application or the technical scheme in the prior art, the following will briefly introduce the attached drawings needed to be used in the embodiment or the description of the prior art. It is obvious that the attached drawings in the following description are only the embodiment of the application. For those skilled in the art, without paying creative labor, other drawings can also be obtained from the provided drawings. 
         FIG. 1  is a cross-sectional view of a tobacco evaporator provided in the first embodiment of the present application; 
         FIG. 2  is a cross-sectional view of a heating core assembly provided in the first embodiment of the present application; 
         FIG. 3  is a cross-sectional view of the tobacco evaporator provided in the first embodiment of the present application during cleaning; 
         FIG. 4  is a cross-sectional view of a tobacco evaporator provided in the second embodiment of the present application; 
         FIG. 5  is a cross-sectional view of the tobacco evaporator provided in the second embodiment of the present application during cleaning; 
         FIG. 6  is a cross-sectional view of a tobacco evaporator provided in the third embodiment of the present application; 
         FIG. 7  is a cross-sectional view of the tobacco evaporator provided in the third embodiment of the present application during cleaning; 
         FIG. 8  is a cross-sectional view of a heating core assembly provided in the fourth embodiment of the present application; 
         FIG. 9  is a flowchart of a tobacco heating control method provided in the fifth embodiment of the present application. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     By providing a tobacco evaporator, the embodiment of the application solves the technical problems existing in the prior art, such as the difficulty of cleaning the tobacco evaporator after use. By designing the air preheating assembly into a detachable component, the user can disassemble the preheating assembly for cleaning. After the preheating assembly is removed from the machine body, the whole air channel forms a hollow channel through the front and back, At the same time, as a detachable part, the preheating assembly can be replaced with a new preheating assembly when it is used for a long time, so as to keep the smoke flow channel clean and the smoke clean. 
     In order to better understand the above technical scheme, the above technical scheme will be described in detail below in combination with the drawings of the description and specific embodiments. It should be understood that the embodiments of the application and the specific features in the embodiments are a detailed description of the technical scheme of the application, rather than a limitation of the technical scheme of the application. Without conflict, the embodiments of the present application and the technical features in the embodiments may be combined with each other. 
     The First Embodiment 
     As shown in  FIG. 1 , the embodiment of the present application provides a tobacco evaporator, comprising a body  1 , a smoke circulation channel  10  vertically communicated along the body  1 , and a heating core assembly  20  disposed on the path of the smoke circulation channel  10 . The heating core assembly  20  comprises a smoke bowl assembly  21 , and a preheating assembly  22  connected to the smoke bowl assembly  21 . The smoke bowl assembly  21  comprises a first bowl body  211  and a second bowl body  212 , and the first bowl body  211  and the second bowl body  212  are of an up-down structure. The first bowl body  211  and the second bowl body  212  are in an integrated structure, the first bowl body  211  is used for accommodating a substance to be evaporated, the second bowl body  212  is used for accommodating the preheating assembly  22 . The second bowl body  212  is elastically fastened to the preheating assembly  22 . The substance to be evaporated can be cigarettes, cut tobacco, herbs or volatile drugs. The preheating assembly  22  is used for when cleaning is needed, being detachably taken out of the second bowl body  212  to clean the smoke circulation channel  10  and pushing the preheating assembly  22  into the fastening position in a set direction after cleaning is completed. 
     The tobacco evaporator further comprises a suction nozzle  2  arranged at one end of the body  1  and a vent pipe  11  arranged at another end of the body  1 . The suction nozzle  2  is arranged upper the first bowl body  211  and is used for users to inhale smoke. One end of the vent pipe  11  abuts against the body  1 , the other end abuts against the bottom of the second bowl body  212 . Cold air enters the tobacco evaporator through vent pipe  11 . 
     As can be seen from  FIG. 1 : the second bowl body  212  extends with a reduced diameter in a direction away from the first bowl body  211  and abuts against the vent pipe  11 . The first bowl body  211  is in a rectangular structure, and the second bowl body  212  includes two parts, one part is in a rectangular structure and the other part connected with the first bowl body  211  is in a trapezoidal structure. The heating core assembly  20  further comprises a clamping portion  23 , transversely arranged in the part of the second bowl body  212  which is in a trapezoidal structure. The clamping portion  23  penetrates the preheating assembly  22 , and abuts against the second bowl body  212 . When cleaning is required, the clamping portion  23  and the preheating assembly  22  are taken out from the second bowl body  212  as a whole. After cleaning, the clamping portion  23  and the preheating assembly  22  are pushed into the fastening position as a whole, and the preheating assembly  22  is elastically fastened to the second bowl body  212  through the clamping portion  23 . 
     In addition, the first bowl body  211  is provided with a mesh filter structure  2112  to prevent the material to be evaporated from falling. The mesh filter structure  2112  is arranged at the connection between the first bowl body  211  and the second bowl body  212 , and a plurality of filter holes are distributed on the mesh filter layer structure  2112 . 
     Further, as can be seen from  FIG. 1 , the tobacco evaporator also includes a flip cover  4 , the flip cover  4  is rotatably connected to the body  1  of the tobacco evaporator. A rotating shaft  13  is arranged at the bottom of the body  1 , one end of the flip cover  4  is provided with a hole  41  matched with the gap of the rotating shaft  13 , and the flip cover  4  can be turned along the rotating shaft  13  by sheathing one end of the hole  41  of the flip cover  4  outside the rotating shaft  13 . When it is necessary to clean the tobacco evaporator, rotate the flip cover  4 , pull out the suction nozzle  2 , and take out the preheating assembly  22  from the second bowl body  212 , so that the smoke circulation channel  10  is easy to be cleaned without dead corners. It should be noted that when the flip cover  4  is in the position in  FIG. 1 , the flip cover  4  can fix the preheating assembly  22 . 
     Further, as can be seen from  FIG. 1 , the tobacco evaporator in the embodiment of the application also includes a battery  5 , which is arranged in the body  1  for supplying power to the tobacco evaporator, and the temperature sensor is fixed on the outer wall of the first bowl body  211  by pasting, welding and other methods for measuring the temperature of the first bowl body  211 , that is, measuring the heating temperature of the material to be evaporated and transmitting the temperature signal; a PCB circuit board  7  arranged on the side wall of one end of the battery  5  away from the heating core assembly  20 ; the controller is arranged on the PCB circuit board  7  and electrically connected with the temperature sensor and the preheating assembly  22  respectively, which is used to receive the induced temperature signal and control the preheating assembly  22  to heat the material to be evaporated according to the preset temperature; in the actual heating process, the controller can adjust the power of the preheating assembly  22  according to the temperature signal transmitted by the temperature sensor, so as to adjust the heating temperature and keep the heating temperature at the set temperature; the switch  3  is arranged on the outer wall of the body  1  and connected with the controller and the battery  5  respectively to control the connection between the controller and the battery  5 ; when the switch is pressed, the preheating assembly  22  starts heating; the display screen  6  is used to display the status parameters of the tobacco generator, such as the power of the battery  5 . 
     Combined with  FIG. 2 , both ends of the clamping portion  23  are provided with elastically stretchable bosses, the preheating assembly  22  is provided with two first openings  221  near an inner diameter of the second bowl body  212  with an abrupt change, the second bowl body  212  is provided with two first grooves  2121  at a position corresponding to the two first openings  221 ; the elastically stretchable bosses on both ends of the clamping portion  23  penetrate the first opening  221 , and is inserted into the second bowl body  212 , and abuts against a side wall of the first groove  2121  to make the preheating assembly  22  elastically fastened to the second bowl body  212 . 
     When cleaning is required, the elastically stretchable bosses at both ends of the clamping portion  23  contract under the action of external force, the preheating assembly  22  is separated from the second bowl body  212 , and the preheating assembly  22  is removed from the second bowl body  212  through the first bowl body  211 . After cleaning, push the preheating assembly  22  back into the second bowl body  212 , and the elastically stretchable bosses at both ends of the clamping portion  23  move along the side wall of the second bowl body  212 . When moving to the first groove  2121 , the elastically stretchable bosses at both ends of the clamping portion  23  are inserted into the side wall of the first groove  2121  and butted with the side wall of the first groove  2121  to make the preheating assembly  22  elastically fastened to the second bowl body  212 . 
     Further, it can be seen from  FIG. 2 : the preheating assembly  22  further comprises a preheating assembly housing  224 , thermal conductive materials  225  placed inside the preheating assembly housing  224  and a heating element  226  sleeved outside the second bowl body  212 . The outer wall of the preheating assembly housing  224  is contacted with the inner wall of the second bowl body  212 , the bottom wall of the preheating assembly housing  224  near one end of the vent pipe  22  is provided with a plurality of vent holes  2221  for cold air entry; the heating element  226  contacted with the outer wall of the second bowl body  212  is used to transfer the heat generated by the heating element  226  to the thermal conductive materials  225  through the second bowl body  212  and the preheating assembly housing  224  to heat the thermal conductive materials  225 . The heated thermal conductive materials  225  exchange heat with the cold air entering the preheating assembly  22  to realize that the cold air is heated, wherein the heating element  226  is a heating wire or an electric heating film. 
     Further, the tobacco evaporator further comprises a heat insulation  30  for insulating the preheating assembly  22  when the heating element  226  generates heat. The heat insulation  30  comprises an insulation ring  31  sleeved at an upper end of the first bowl body  211 , an insulation sleeve  32  arranged outside the second bowl body  212 , a sealing silica gel  33  connecting the insulation ring  31  and the insulation sleeve  32 , and the inner wall of the insulation ring  31  is contacted with the outer wall of the first bowl body  212 ; the inner wall of the sealing silica gel  33  is contacted with the first bowl body  211 , the outer wall is connected with the insulation sleeve  32 ; the insulation sleeve  32  maintains a certain distance from both the first bowl body  211  and the second bowl body  212 ; one end of the insulation sleeve  32  is connected with the sealing silica gel  33 , the other end of the insulation sleeve  32  is bent to the vent pipe  11 . The heat insulation  30  forms a closed thermal insulation space with the smoke bowl assembly  21  and the vent pipe  11 , and the thermal insulation space is filled with thermal insulation materials to further insulate the tobacco evaporator and prevent heat loss into the air. As can be seen from  FIG. 2 , a step groove is set at the connection between the sealing silica gel  33  and the insulation sleeve  32  for positioning the insulation sleeve  32  for easy installation. 
     The thermal conductive materials  225  is a material with large heat capacity and good heat conductivity, such as metal, which is convenient for better heat conduction. The clamping portion  23  is an elastic part that can produce deformation, and can be other elastomers such as elastic needle or elastic sheet, which can meet the requirements of detachable use. 
     As shown in  FIG. 3 , when the tobacco evaporator is cleaned, the preheating assembly  22  will be taken out from the second bowl body  212  through the first bowl body  211  in the direction shown in the figure, and the flip cover  4  will be opened to the position shown in  FIG. 3 , so that the smoke circulation channel  10  forms a hollow channel without dead corners inside, which is convenient for cleaning. 
     The Second Embodiment 
     As shown in  FIG. 4 , the difference between the second embodiment and the first embodiment is that the setting position of preheating assembly  22  and the removal direction of preheating assembly  22  during cleaning are different. Specifically, the tobacco evaporator of the second embodiment comprises a support tube  12  for supporting the second bowl body  212 . One end of the support tube  12  abuts against the body  1 , the other end of the support tube  12  extends to the second bowl body  212  and abuts against a bottom of the second bowl body  212 . The second bowl body  212  extends with a reduced diameter in a direction away from the first bowl body  211 . One end of the vent pipe  11  abuts against the body  1 , the other end of the vent pipe  11  extends to the preheating assembly  22  and is fixedly connected with a bottom of the preheating assembly  22 . Preferably, the vent pipe  11  and the bottom of the preheating assembly  22  can be fixedly connected by riveting; during cleaning, the preheating assembly  22  can be taken out from the second bowl body  212  through the setting position of the flip cover  4  by pulling the vent pipe  11 , which is convenient for operation. 
     Further, the clamping portion  23  is transversely arranged in the second bowl body  212 , penetrates the preheating assembly  22 , and abuts against the second bowl body  212 . When cleaning is needed, the preheating assembly  22  is taken out of the second bowl body  212 ; after cleaning, the clamping portion  23  and the preheating assembly  22  are pushed into a fastening position to make the clamping portion  23  elastically fastened to the second bowl body  212 . 
     As can be seen from  FIG. 4 : the preheating assembly  22  is provided with two second openings  222  near an inner diameter of the second bowl body  212  with an abrupt change; the second bowl body  212  is provided with two second grooves  2122  at a position corresponding to the two second openings  222 ; the elastically stretchable bosses on both ends of the clamping portion  23  penetrate the second opening  222 , and is inserted into the second bowl body  212 , and abuts against a side wall of the second groove  2122  to make the preheating assembly  22  elastically fastened to the second bowl body  212 . 
     In combination with  FIG. 5 , when the tobacco evaporator needs to be cleaned, rotate the flip cover  4  to the position in the figure, the elastically stretchable bosses at both ends of the clamping portion  23  contract under the action of external force, the preheating assembly  22  is separated from the second bowl body  212 , and the preheating assembly  22  is taken out from the second bowl body  212  away from the first bowl body  211  to the outside of the body  1  by pulling the vent pipe  11 . After cleaning, push the preheating assembly  22  back into the second bowl body  212 , and the elastically stretchable bosses at both ends of the clamping portion  23  move along the side wall of the second bowl body  212 . When moving to the second groove  2122 , the elastically stretchable bosses at both ends of the clamping portion  23  are inserted into the side wall of the second groove  2122  and butted with the side wall of the second groove  2122 . As can be seen from  FIG. 5 , one end of the vent pipe  11  close to the flip cover  4  is a hollow handle to facilitate the removal of the preheating assembly  22 , and in this embodiment the preheating assembly  22  is taken out from one side of the flip cover. 
     The Third Embodiment 
     The difference between this embodiment and the first two embodiments is that the position of the preheating assembly  22  and the structure of the smoke bowl assembly  21  are different. Specifically, as shown in  FIG. 6 , the second bowl body  212  is sleeved around the first bowl body  211 , the first bowl body  211  is used to contain the material to be evaporated and the preheating assembly  22 , and the first bowl body  211  and the second bowl body  212  can be elastically connected. 
     Further, one end of the second bowl body  212  away from the suction nozzle  2  butts with the vent pipe  11 , the other end of the vent pipe  11  butts with the body  1 ; the clamping portion  23  is placed laterally inside the first bowl body  211 , and the clamping portion  23  passes through the first bowl body  211  and butts with the second bowl body  212 . When cleaning is required, the clamping portion  23  and the first bowl body  211  are taken out from the second bowl body  212 . After cleaning, push the clamping portion  23  and the first bowl body  211  into the fastening position, and hold the clamping portion  23  against the second bowl body  212  to realize the fastening connection between the first bowl body  211  and the second bowl body  212 . 
     Further, it can be seen from  FIG. 6 : both ends of the clamping portion  23  are provided with elastically stretchable bosses; the first bowl body  211  is provided with two fourth openings  2111  near the middle, the second bowl body  212  is provided with two third grooves  2123  at a position corresponding to the two fourth openings  2111 ; the elastically stretchable bosses on both ends of the clamping portion  23  penetrate the fourth opening  2111 , and is inserted into a side wall of the second bowl body  212 , and abuts against a side wall of the third groove  2123  to make the preheating assembly  22  elastically fastened to the second bowl body  212 . 
     When cleaning is required, the elastically stretchable bosses on both ends of the clamping portion  23  contract under the action of external force, the first bowl body  211  is separated from the second bowl body  212 , the first bowl body  211  is taken out to the outside of the body  1 ; after cleaning, the first bowl body  211  is pushed back to the inside of the second bowl body  212 , and the elastically stretchable bosses on both ends of the clamping portion  23  move along the side wall of the second bowl body  212 . When moving to the third groove  2123 , the elastically stretchable bosses on both ends of the clamping portion  23  are inserted into the side wall of the third groove  2123  and butted with the side wall of the third groove  2123 . 
     Referring to  FIG. 7 , when the tobacco evaporator is cleaned, take out the first bowl body  211  containing the substance to be evaporated and the preheating assembly  22  from the second bowl body  212 , and rotate the flip cover  4  to the position shown in the figure, the smoke circulation channel  10  of the tobacco evaporator has no dead corner and is convenient for cleaning. 
     The Fourth Embodiment 
     The difference between this embodiment and the above embodiment is that the structure of the preheating assembly  22  of this embodiment is different from that of the above embodiment. Specifically, it can be seen from  FIG. 8 : the preheating assembly  22  comprises a preheating assembly housing  224 , a spiral part  227  placed under the preheating assembly housing  224  and abutted against the preheating assembly housing  224 , and a heating element  226  sleeved outside the second bowl body  212 ; the bottom wall of the preheating assembly housing  224  close to the vent pipe  11  is provided with an air hole  2222  adapted to the vent pipe  11  for cold air entry; the heating element  226  used for heating cold air contacts with an outer wall of the second bowl body  212  and wraps the whole second bowl body  212 ; an outer wall of the spiral part  227  is contacted with an inner wall of the second bowl body  212 ; the outer wall of the spiral part  227  and the inner wall of the second bowl body  212  form a spiral preheating channel through which the cold air passes to realize the uniform heating of the cold air. Compared with the preheating assembly  22  in the first embodiment, the advantage of this embodiment is that the spiral part  227  in this embodiment is in direct contact with the second bowl body  212 ; the heat transfer medium passes from the heating element  226  to the cold air is less, the heat transfer efficiency is higher, and the cold air is more uniformly heated. 
     The Fifth Embodiment 
     The application further tobacco provides a heating control method comprising the following steps: 
     S1. a preheating assembly  22  arranged inside a second bowl body  212  and elastically fastened to the second bowl body  212  heating cold air coming into the second bowl body  212 . Specifically, the preheating assembly  22  includes thermal conductive materials  225  and a heating element  226  sleeved outside the second bowl body  212 . The heating element  226  is in contact with the outer wall of the second bowl body  212  for transferring the heat generated by the heating element  226  to the thermal conductive materials  225  through the second bowl body  212  to heat the thermal conductive materials  225 . The heated thermal conductive materials  225  exchange heat with the cold air entering the preheating assembly  22  to realize that the cold air is heated, wherein the heating element  226  is a heating wire or an electric heating film. 
     S2. the heated cold air entering a first bowl body  211 , heating the substance to be evaporated placed in the first bowl body  211 , and evaporating effective components in the substance to be evaporated. The first bowl body  211  is provided with a mesh filter structure  2112  to prevent the material to be evaporated from falling, and a plurality of filter holes are distributed on the mesh filter layer structure  2112 . At the same time, a plurality of filter holes can realize the uniform heating of the material to be evaporated and improve the evaporation efficiency of the material to be evaporated. 
     S3. when cleaning is needed, the preheating assembly  22  is taken out of the second bowl body  212  and is pushed into a fastening position after cleaning is completed. Specifically, after the preheating assembly  22  is taken out from the second bowl body  212 , a hollow channel without dead corner is formed in the smoke circulation channel  10  of the tobacco evaporator to facilitate cleaning. 
     By designing the air preheating assembly as a detachable component, the user can disassemble the preheating assembly for cleaning; after the preheating assembly is removed from the body, the whole air passage forms a hollow passage through the front and back, without cleaning dead corner, which is convenient for cleaning; at the same time, as a detachable part, the preheating assembly can be replaced with a new one when it is used for a long time, so as to keep the air flow channel clean and the flue gas clean. 
     Although preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including preferred embodiments and all changes and modifications falling within the scope of the present application. 
     Obviously, those skilled in the art can make various changes and modifications to the application without departing from the spirit and scope of the application. Thus, if these modifications and variants of the application fall within the scope of the claims of the application and its equivalent technology, the application is also intended to include these modifications and variants.