Household coffee roaster with improved heating structure

Abstract

The utility model discloses a domestic coffee bean roaster of improved heating structure, and the lower part of fixed stand is fixedly installed in the upper part of middle layer heat insulation frame, and the upper layer mica plate is fixedly installed in the upper part of fixed stand, and the lower layer mica plate is fixedly installed in the lower part of middle layer heat insulation frame, and spiral heating wire is installed around the side of fixed stand and is located between upper layer mica plate and middle layer heat insulation frame, and open type temperature controller and fuse are arranged in lower layer mica plate respectively. Through the middle layer heat insulation frame, the heat of spiral heating wire is blocked and radiated downward, the temperature of lower layer mica plate is reduced to below 150 DEG C, the open type temperature controller can be used, the open type temperature controller is small in size, so it can be installed on the position of lower layer mica plate and close to fuse, to shorten the distance between open type temperature controller and fuse, improve the heat protection, reduce the production cost while improving the heat protection performance, improve the cold air heating uniformity, avoid the hot air backflow, improve the reliability and stability.

Description

Technical Field

[0001] This utility model relates to the field of home coffee roaster technology, and in particular to a home coffee roaster with an improved heating structure. Background Technology

[0002] The aroma and flavor of coffee primarily come from volatile compounds produced during the roasting process. These compounds are the source of coffee's complex flavor profile, including fruity, floral, caramel, and nutty notes. However, they are extremely unstable and gradually evaporate or decompose over time, influenced by oxygen, temperature, and humidity. Therefore, the optimal consumption period for coffee beans is within 1 to 3 months. Furthermore, depending on the coffee bean variety and individual taste preferences, coffee beans are roasted to different degrees—light, medium, dark, and hot—based on roasting temperature and time. With the improvement of living standards, more and more people are choosing to roast coffee beans at home using home coffee roasters.

[0003] Home coffee roasters are small in size. Existing home coffee roasters typically have a heating structure consisting of a metal casing and a heating element inside. A fan blows cool air upwards from the bottom of the metal casing, heats it up in the heating element, and then blows it out from the top of the casing to the coffee bean container. The heating element consists of an upper and lower mica frame, with the heating wire fixed between them. A fuse is located on the bottom of the lower mica frame for easy connection to the heating wire. Since the roasting temperature needs to reach a maximum of 230℃, and the temperature inside the metal casing is even higher, a snap-action thermostat is necessary. However, snap-action thermostats are bulky and cannot be installed on the lower mica frame. Instead, they are installed in the upper part of the metal casing, resulting in a larger distance between the fuse and the snap-action thermostat, reducing thermal protection performance. Furthermore, an additional seal is required between the metal casing and the snap-action thermostat, making the manufacturing process complex and costly.

[0004] In addition, although the metal casing is heat-resistant, its high thermal conductivity can easily heat the external circuit board. To reduce heat loss and lower costs, the metal casing is often small in size, which reduces the internal volume of the metal casing. When the cold air is heated, the volume expands dramatically, and the hot air is prone to backflow. Especially when the temperature control is inaccurate, the hot air backflow blows towards the fan, causing the fan temperature to rise, resulting in poor reliability and stability. It can also cause uneven heating of the cold air, affecting the baking effect. Therefore, it is necessary to improve this. Utility Model Content

[0005] To address the shortcomings of existing technologies, the purpose of this utility model is to provide a home coffee roaster with an improved heating structure, which shortens the distance between the thermostat and the fuse, expands the range of thermostat options, reduces costs, improves the uniformity of cold air heating, prevents hot air backflow, and enhances reliability and stability.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a household coffee roaster with an improved heating structure, comprising a main body and a bean cup movably mounted on the upper part of the main body. The main body contains a heating device and a control device. The heating device includes a heating shell, a heating mechanism, a centrifugal impeller, and a drive motor. The heating mechanism is located inside the heating shell, and the centrifugal impeller is rotatably mounted inside the heating shell and located below the heating mechanism. The drive motor is fixedly mounted on the lower part of the heating shell and is connected to the centrifugal impeller for transmission. The heating mechanism includes an upper mica plate, a middle heat insulation frame, a lower mica plate, a fixed support frame, an open thermostat, a fuse, and at least one spiral heating wire. The spiral heating wire, the open thermostat, and the fuse are connected in series via leads and electrically connected to the control circuit.

[0007] The lower part of the fixed stand is fixedly installed on the upper part of the middle heat insulation frame. The upper mica plate is fixedly installed on the upper part of the fixed stand, and the lower mica plate is fixedly installed on the lower part of the middle heat insulation frame. The spiral heating wire is installed around the side of the fixed stand and is located between the upper mica plate and the middle heat insulation frame. The open-type thermostat and fuse are respectively set on the lower mica plate.

[0008] In a further technical solution, the middle layer insulation frame includes an insulation board and multiple insulation columns. The upper end of each insulation column is fixedly connected to the bottom surface of the insulation board, and the lower end of each insulation column is fixedly connected to the top surface of the lower layer mica board. An insulation gap is formed between the insulation board and the lower layer mica board.

[0009] The heating housing includes an upper heating shell, a lower heating shell, a heating sealing ring, and a heat-insulating mica sheet. The upper edge of the lower heating shell has a flange, and the outer edge of the flange extends outward to form a mounting ring. The lower edge of the upper heating shell is fixedly connected to the mounting ring by screws. The mounting ring is fixedly connected to the main body by screws. The lower part of the inner wall of the upper heating shell has a mounting step. The lower mica sheet is clamped and fixed between the mounting step and the flange. The heat-insulating mica sheet is set on the inner wall of the upper heating shell and is located around the spiral heating wire. The heating sealing ring is set between the outer side of the flange and the inner wall of the upper heating shell. The upper heating shell has a heating cavity inside, and the lower heating shell has an airflow cavity inside. The heating mechanism is set in the heating cavity, and the centrifugal fan is rotated and installed in the airflow cavity. Both the upper and lower heating shells are made of plastic.

[0010] In a further technical solution, the lower mica plate is provided with multiple lower air passage holes that penetrate the lower mica plate at intervals along the circumferential direction, and the upper mica plate is provided with multiple upper air passage holes at intervals along the circumferential direction. The outer diameter of the upper mica plate is smaller than the outer diameter of the lower mica plate, and the spiral heating wire is located above the lower air passage holes and in the middle of the heating cavity along the axial direction.

[0011] The open-type thermostat and fuse are fixedly installed on the bottom surface of the lower mica plate by hollow rivets and are located inside each of the lower air vents. Each hollow rivet is equipped with a sealing plug.

[0012] In a further technical solution, there is an air gap between the outer edge of the centrifugal impeller and the inner wall of the heating lower shell. The lower air passage is located above the air gap. The width 'a' of the lower air passage in the radial direction is less than the maximum width 'b' of the air gap. The width of the air gap is 7-9 mm.

[0013] In a further technical solution, the lower part of the heating shell is provided with a motor mounting slot with the opening facing downward. The drive motor is fixedly installed in the motor mounting slot, and the output shaft of the drive motor passes through the heating shell and is connected to the centrifugal impeller.

[0014] The upper part of the motor mounting slot has multiple motor heat dissipation holes spaced apart along the circumference, which connect to the airflow chambers.

[0015] The lower part of the main body is provided with multiple first air inlets. The outer periphery of the motor mounting slot is provided with multiple second air inlets that connect to the airflow chambers at intervals along the circumferential direction. An air inlet rib is formed between two adjacent second air inlets, which are inclined in the radial direction. A third air inlet is provided through the air inlet rib.

[0016] The upper part of the main body is provided with a connecting card slot, the lower part of the bean cup is connected to the connecting card slot with a snap fastener, the middle part of the connecting card slot is provided with a second air outlet that connects to the inner cavity of the main body, the upper part of the heating shell is provided with a first air outlet that connects to the heating cavity, and the first air outlet and the second air outlet are connected.

[0017] In a further technical solution, an upper sealing ring extends downward from the inner edge of the second air outlet, and an upper connecting ring is provided around the outer periphery of the upper sealing ring. A protective connecting cylinder is formed in the first air outlet, and a lower connecting groove is provided at the upper part of the protective connecting cylinder. The upper connecting ring is inserted into the lower connecting groove, and a connecting sealing ring is provided between the inner wall of the upper sealing ring and the lower connecting groove. The connecting sealing ring is sealed and fitted with the bean cup.

[0018] In a further technical solution, a protective net is installed inside the protective connecting cylinder. The outer edge of the protective net has multiple outwardly protruding limiting protrusions spaced along the circumferential direction. The inner wall of the protective connecting cylinder has multiple limiting grooves spaced along the circumferential direction, which correspond to the limiting protrusions. The limiting protrusions and limiting grooves are matched for limiting. Each limiting groove has a fixing pin installed on its side wall. A protective step is provided at the lower part of the inner wall of the protective connecting cylinder. The protective net is clamped and fixed between each fixing pin and the protective step.

[0019] In a further technical solution, the fixed frame includes multiple mica uprights that are cross-connected and fixed in the middle. A sensing support plate extends upward from the middle of the upper mica upright. The sensing support plate extends out of the upper mica upright towards the bean cup. A temperature sensor is fixedly installed on the upper part of the upper mica upright. The temperature sensor is electrically connected to the control device. The distance between the temperature sensor and the bean cup is 5-8mm.

[0020] In a further technical solution, a wire-passing groove is provided on one side of the flange of the lower heating shell, and a wire-passing hole is provided on the upper heating shell corresponding to the position of the wire-passing groove. The lead wire of the fuse passes downward through the lower mica plate, connects to the open-type thermostat and the fuse, and then passes through the wire-passing groove and the wire-passing hole in sequence to be electrically connected to the control device. The wire-passing groove and / or the wire-passing hole are filled with heat-resistant sealant.

[0021] In a further technical solution, the bean cup includes a baking inner liner, an insulated cup body, and a sealing cup lid. The baking inner liner is fixedly installed inside the insulated cup body, the lower part of the insulated cup body is snapped to the upper part of the main body, and the sealing cup lid is placed on the upper part of the insulated cup body.

[0022] The sealing cup lid includes an upper lid and a lower lid, which are snapped together. The upper lid opens downwards and has an upper annular chip baffle inside. The lower lid has a mounting hole in its center, from which the lower annular chip baffle extends upwards. An annular chip collection groove is formed between the lower annular chip baffle and the inner wall of the lower lid. The lower end of the upper annular chip baffle is inserted into the chip collection groove. An annular filter screen is provided between the upper annular chip baffle and the inner wall of the upper lid. Multiple vent holes are provided on the upper part of the upper lid along the circumferential direction corresponding to the position of the annular filter screen. A first vent gap is formed between the upper annular chip baffle and the lower annular chip baffle. A second vent gap is formed between the upper annular chip baffle and the bottom of the chip collection groove. A third vent gap is formed between the upper annular chip baffle and the inner wall of the lower lid. The first vent gap is connected to the baking liner. The second vent gap is connected to the first vent gap. The third vent gap is connected to each vent hole through the inner cavity of the upper lid.

[0023] The baking liner is located above the heating mechanism. The lower part of the baking liner has multiple baking heating holes, and the upper part of the baking liner protrudes from the upper end of the insulated cup body and is inserted into the mounting hole.

[0024] A side handle is provided on one side of the insulated cup body, and an upper handle is provided on the upper part of the lid body;

[0025] The upper surface of the insulated cup body is provided with two anti-rotation protrusions, and the lower surface of the lower cover is provided with two anti-rotation grooves corresponding to the anti-rotation protrusions. The two anti-rotation protrusions are respectively inserted into the two anti-rotation grooves.

[0026] The advantages of this invention compared to existing technologies are as follows: by using the middle heat insulation frame to block the downward radiation of heat from the spiral heating wire, the temperature of the lower mica plate is reduced to below 150°C, thus enabling the use of an open-type thermostat. The open-type thermostat is smaller in size and can be installed on the lower mica plate close to the fuse, thereby shortening the distance between the open-type thermostat and the fuse and improving thermal protection. Furthermore, the market price of the open-type thermostat is lower than that of the snap-action thermostat, reducing production costs while improving thermal protection performance. The open-type temperature controller and temperature sensor are both located inside the heating shell, eliminating the need for additional openings on the heating shell for sealing. This simplifies the assembly process, improves production efficiency, and reduces production costs. The heating shell is made of high-temperature resistant plastic and insulated with heat-insulating mica sheets. This allows for an increase in the volume of the heating shell, reducing its thermal conductivity and improving its insulation. This not only prevents heat loss from affecting the drive motor and control device, improving reliability and stability, but also reduces energy consumption, resulting in lower production and operating costs. As the heating shell increases in volume, the cold and hot air inside can be mixed more evenly, leading to a more accurate baking temperature curve. A certain distance is maintained between the spiral heating wire and the centrifugal impeller through the insulation gap. Cold air enters the heating chamber only through the lower air passage. When heated and expanding, the large cavity buffers the cold air. The expansion of the heated air relatively reduces the pressure inside the heating shell, ensuring that the pressure inside the heating shell is lower than the air pressure generated by the drive impeller. This prevents localized downward convection of hot air from exchanging with the air in the airflow chamber, avoiding excessively high local temperatures within the heating chamber and preventing hot air backflow, thus protecting the drive motor. The temperature sensor is positioned below and near the bean cup, improving the accuracy of temperature detection inside the bean cup, resulting in more precise temperature control and improved roasting results. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] Figure 1 This is a schematic diagram of the structure of this utility model;

[0029] Figure 2 This is an exploded view of the present invention;

[0030] Figure 3 This is a cross-sectional view of the present invention;

[0031] Figure 4 This is the utility model Figure 3 Enlarged view of part A;

[0032] Figure 5 This is the utility model Figure 3 Enlarged view of part B;

[0033] Figure 6This is a schematic diagram of the heating device of this utility model;

[0034] Figure 7 This is a cross-sectional view of the heating device of this utility model;

[0035] Figure 8 This is an exploded view of the heating device of this utility model;

[0036] Figure 9 This is a bottom view of the heating lower shell of this utility model;

[0037] Figure 10 This is an exploded view of the heating mechanism of this utility model;

[0038] Figure 11 This is a diagram showing the airflow direction during baking according to this utility model.

[0039] In the picture:

[0040] 1 Main unit body, 11 First air inlet, 12 Connecting bracket, 13 Second air outlet, 14 Upper sealing ring, 15 Upper connecting ring, 16 Connecting sealing ring;

[0041] 2. Bean cup, 21. Baking inner liner, 22. Insulated cup body, 221. Side handle, 23. Sealed cup lid, 231. Upper lid, 2311. Upper annular chip baffle, 2312. Vent hole, 2313. Upper handle, 232. Lower lid, 2321. Mounting hole, 2322. Lower annular chip baffle, 2323. Chip collection groove, 233. Annular filter screen, 234. First vent gap, 235. Second vent gap, 236. Third vent gap;

[0042] 3 Heating shell, 31 Heating upper shell, 311 Heating cavity, 312 Mounting step, 313 First air outlet, 314 Protective connecting cylinder, 3141 Lower connecting groove, 3142 Limiting slide groove, 3143 Protective step, 315 Protective net, 3151 Limiting protrusion, 316 Fixing pin, 317 Wire hole, 32 Heating lower shell, 321 Airflow cavity, 322 Flanged edge, 3221 Mounting ring, 3222 Wire groove, 323 Motor mounting groove, 324 Motor heat dissipation hole, 325 Second air inlet, 326 Air inlet rib, 3261 Third air inlet, 327 Heating sealing ring, 328 Heat insulation mica sheet, 33 Centrifugal impeller, 34 Drive motor, 35 Exhaust gap;

[0043] 4 Heating mechanism, 41 Upper mica board, 411 Upper ventilation hole, 42 Middle insulation frame, 421 Insulation board, 422 Insulation support column, 43 Lower mica board, 431 Lower ventilation hole, 44 Fixed frame, 441 Mica support plate, 442 Induction support plate, 45 Open thermostat, 46 Fuse, 47 Spiral heating wire, 48 Insulation gap, 49 Sealing plug;

[0044] 5. Temperature sensor. Detailed Implementation

[0045] The following are merely preferred embodiments of the present invention and do not limit the scope of protection of the present invention.

[0046] A home coffee roaster with an improved heating structure, such as Figures 1 to 11 As shown, the device includes a main body 1 and a bean cup 2 movably mounted on the upper part of the main body 1. The main body 1 contains a heating device and a control device. The heating device includes a heating shell 3, a heating mechanism 4, a centrifugal impeller 33, and a drive motor 34. The heating mechanism 4 is located inside the heating shell 3. The centrifugal impeller 33 is rotatably mounted inside the heating shell 3 and located below the heating mechanism 4. The drive motor 34 is fixedly mounted on the lower part of the heating shell 3 and is connected to the centrifugal impeller 33 for transmission. The heating mechanism 4 includes an upper mica plate 41, a middle insulation frame 42, a lower mica plate 43, a fixed support frame 44, an open-type thermostat 45, a fuse 46, and at least one spiral heating wire 47. The spiral heating wire 47, the open-type thermostat 45, and the fuse 46 are connected in series with the control circuit via leads. Electrically connected, the lower part of the fixed stand 44 is fixedly installed on the upper part of the middle heat insulation frame 42, the upper mica plate 41 is fixedly installed on the upper part of the fixed stand 44, the lower mica plate 43 is fixedly installed on the lower part of the middle heat insulation frame 42, the spiral heating wire 47 is installed around the side of the fixed stand 44 and is located between the upper mica plate 41 and the middle heat insulation frame 42, and the open thermostat 45 and the fuse 46 are respectively set on the lower mica plate 43; the middle heat insulation frame 42 includes a heat insulation plate 421 and a plurality of heat insulation pillars 422, the upper end of each heat insulation pillar 422 is fixedly connected to the bottom surface of the heat insulation plate 421, and the lower end of each heat insulation pillar 422 is fixedly connected to the top surface of the lower mica plate 43, and a heat insulation gap 48 is formed between the heat insulation plate 421 and the lower mica plate 43.

[0047] Traditional home coffee roasters have a heating element 4 consisting of an upper mica plate 41 and a lower mica plate 43, with a spiral heating wire 47 fixed between them. Because the spiral heating wire 47 is close to the lower mica plate 43, the lower mica plate 43 reaches a maximum temperature of over 240°C during roasting. However, the maximum operating temperature of an open-type thermostat 45 is only 160°C. Therefore, traditional home coffee roasters can only use a snap-action thermostat for their heating element 4. The snap-action thermostat is not only expensive and bulky, but also lacks installation space on the lower mica plate 43, requiring installation only through a hole in the heating shell 3. This results in complex assembly processes, high production costs, and the need for additional sealing between the heating shell 3 and the snap-action thermostat. Furthermore, the snap-action thermostat is far from the fuse 46. Because the lower mica plate 43 is close to the spiral heating wire 47, the temperature at the location of the fuse 46 will be higher than the temperature at the location of the snap-action thermostat, easily causing the fuse 46 to melt first and then snap-action. If the snap-action thermostat fails to operate, the snap-action thermostat cannot function stably. Increasing the protection temperature of fuse 46 would make it difficult for fuse 46 to melt, thus failing to provide thermal protection. This invention uses a middle heat insulation frame 42 to block the downward radiation of heat from the spiral heating wire 47, reducing the temperature of the lower mica plate 43 to below 150°C. This allows for the use of an open-type thermostat 45. The open-type thermostat 45 is smaller and can be installed on the lower mica plate 43 close to fuse 46, shortening the distance between the open-type thermostat 45 and fuse 46. When the local maximum temperature inside the heating shell 3 reaches above 250°C, the temperature near the open-type thermostat 45 reaches 150°C, causing the open-type thermostat 45 to cut off first. When the open-type thermostat 45 malfunctions, fuse 46 melts, improving thermal protection. Furthermore, the market price of the open-type thermostat 45 is lower than that of the snap-action thermostat, reducing production costs while improving thermal protection performance. The open-type thermostat 45 is located inside the heating housing, eliminating the need for additional openings on the heating housing 3 for sealing, simplifying the assembly process, improving production efficiency, and reducing production costs.

[0048] Specifically, such as Figures 6 to 8As shown, the heating housing 3 includes an upper heating housing 31, a lower heating housing 32, a heating sealing ring 327, and a heat-insulating mica sheet 328. The lower heating housing 32 has a flange 322 along its upper edge, and a mounting ring 3221 extends outward from the outer edge of the flange 322. The lower edge of the upper heating housing 31 is fixedly connected to the mounting ring 3221 by screws. The mounting ring 3221 is fixedly connected to the main body 1 by screws. An installation step 312 is provided at the lower part of the inner wall of the upper heating housing 31. A lower mica sheet 43 is clamped and fixed between the installation step 312 and the flange 322. The heat-insulating mica sheet 328 is provided with… A heating sealing ring 327 is disposed between the outer side of the flange 322 and the inner wall of the heating upper shell 31 and the spiral heating wire 47. The heating upper shell 31 has a heating chamber 311 inside, and the heating lower shell 32 has an airflow chamber 321 inside. The heating mechanism 4 is disposed in the heating chamber 311, and the centrifugal fan 33 is rotatably mounted in the airflow chamber 321. Both the heating upper shell 31 and the heating lower shell 32 are made of plastic. The heating upper shell 31 is made of high-temperature resistant plastic, specifically high-temperature resistant PPS. Due to the middle heat insulation frame 42 and the heat insulation gap 48, the temperature inside the airflow chamber 321 is below 150℃. Therefore, the heating lower shell 32 does not require high-temperature resistant materials, further reducing production costs.

[0049] Traditional home coffee roasters require openings in the heating shell 3 to install a snap-action thermostat. To ensure structural strength and high-temperature resistance, the heating shell 3 is often made of metal. However, due to the high thermal conductivity of metal, the high temperature of the heating chamber 311 is easily conducted to the main body 1 through the heating shell 3. This not only causes the temperature of the drive motor 34 and control device to rise, but also causes heat loss from the heating chamber 311, leading to unstable operation of the drive motor 34 and control device, increased power consumption, and slow heating speed. To solve this problem, traditional home coffee roasters... While reducing the volume of the heating shell 3 in a coffee roaster can decrease heat loss and dissipation, this also reduces the size of the heating chamber 311. Furthermore, since the heating chamber 311 and the airflow chamber 321 are in the same cavity, the heated air expands dramatically, increasing the pressure within the heating chamber 311 and making it prone to backflow. This can cause the drive motor 34 to be continuously heated, leading to shutdown and inconsistent reliability and stability. Additionally, the small mixing space between cold and hot air results in uneven mixing and inconsistent temperature of the hot air blown onto the bean cup 2. In contrast, the open-type design of this invention... The thermostat 45 is mounted on the lower mica plate 43, eliminating the need for openings in the heating shell 3. Therefore, the heating shell 3 is made of high-temperature resistant plastic and insulated by a heat-insulating mica sheet 328. By increasing the volume of the heating shell 3, the volume of the heating chamber 311 is increased, allowing for more thorough mixing of cold and hot air, preventing localized overheating, and ensuring more uniform mixing. This maintains a constant temperature of the hot air blowing onto the bean cup 2, resulting in a more accurate roasting temperature curve. Furthermore, as the volume of the heating chamber 311 increases, the pressure within it decreases, thus preventing hot air from... The downward flow prevents heating of the drive motor 34, improving stability and reliability. Due to the relatively poor thermal conductivity and high thermal insulation of plastic material compared to metal material, the temperature loss rate of the heating chamber 311 is slow, and the drive motor 34 and control device are not easily heated, resulting in more stable operation, lower energy consumption, and reduced production and operating costs. In addition, for the sealing of the heating shell 3, only the upper heating shell 31 and the lower heating shell 32 need to be fixed by screws and sealed by the heating sealing ring 327. There is no need to seal other holes, simplifying the assembly process and improving production efficiency.

[0050] Specifically, such as Figures 7 to 10As shown, the lower mica plate 43 has multiple lower air passage holes 431 spaced apart along the circumference, and the upper mica plate 41 has multiple upper air passage holes 411 spaced apart along the circumference. The outer diameter of the upper mica plate 41 is smaller than the outer diameter of the lower mica plate 43. The spiral heating wire 47 is located above the lower air passage holes 431 and in the middle of the heating cavity 311 along the axial direction. The open-type thermostat 45 and the fuse 46 are fixedly installed on the bottom surface of the lower mica plate 43 by hollow rivets and are located inside each lower air passage hole 431. Each hollow rivet is provided with a sealing plug 49. In traditional designs, the heating chamber 311 and the airflow chamber 321 are in the same cavity without any separation, which easily leads to turbulence and hot air backflow within the heating shell 3, and can cause localized overheating. In contrast, the lower mica plate 43 of this invention is clamped and fixed between the upper heating shell 31 and the lower heating shell 32. The lower mica plate 43 relatively separates the heating chamber 311 and the airflow chamber 321, which are connected only by lower air passages 431. Each lower air passage 431 is located below the spiral heating wire 47. When cold air enters the heating chamber 311 through the lower air passages 431, it blows directly onto the spiral heating wire 47, is heated, and then blows upwards, minimizing turbulence. To prevent hot air backflow and maintain a relatively low temperature at the center of the heating chamber 311, facilitating electrical connection via lead wires, the lower mica plate 43 requires hollow rivets to connect the heating chamber 311 and the airflow chamber 321 via lead wires. Since the spiral heating wire 47 needs to be electrically connected to the open-type thermostat 45 and fuse 46, hollow rivets are installed. These rivets connect the heating chamber 311 and the airflow chamber 321, and convection can easily occur between them through the lower air passage 431 and the hollow rivets. Therefore, the hollow rivets are sealed with sealing plugs 49 to ensure that the heating chamber 311 and the airflow chamber 321 can only connect through the lower air passage 431, preventing localized downward convection of hot air from exchanging with the air in the airflow chamber 321.

[0051] Specifically, such as Figure 7 As shown, there is an air gap 35 between the outer edge of the centrifugal impeller 33 and the inner wall of the heating lower shell 32. The lower air passage 431 is located above the air gap 35. The radial width 'a' of the lower air passage 431 is less than the maximum width 'b' of the air gap 35, and the width of the air gap 35 is 7-9 mm. Since the cold air generated by the centrifugal impeller 33 is blown upward from the air gap 35, and since the radial width 'a' of the lower air passage 431 is less than the maximum width 'b' of the air gap 35, the air pressure inside the lower air passage 431 is prevented from being too low, further preventing hot air backflow. It also reduces the local high temperature of the heating chamber 311, shortening the temperature difference between the heating chamber 311 and the bean cup 2.

[0052] Specifically, such as Figures 6 to 9As shown, the lower part of the heating lower shell 32 is provided with a downward-facing motor mounting slot 323. The drive motor 34 is fixedly installed in the motor mounting slot 323, and the output shaft of the drive motor 34 passes through the heating lower shell 32 and is connected to the centrifugal impeller 33. The upper part of the motor mounting slot 323 is provided with multiple motor heat dissipation holes 324 that communicate with the airflow chamber 321 at intervals along the circumferential direction. The drive motor 34 is fixedly installed on the heating lower shell 32 through the motor mounting slot 323. The drive motor 34 does not need to be connected to the main body 1, which simplifies the assembly process. The cool air in the airflow chamber 321 can be blown towards the drive motor 34 through the motor heat dissipation holes 324 to dissipate heat from the drive motor 34 and improve the operating stability of the drive motor 34. The lower part of the main body 1 is provided with multiple first air inlets 11. Multiple second air inlets 325, connecting to airflow chambers 321, are spaced apart along the circumferential direction around the motor mounting slot 323. An air inlet rib 326, arranged radially inclined, is formed between adjacent second air inlets 325. A third air inlet rib 326 is provided through the rib 326. A connecting bracket 12 is provided at the upper part of the main body 1. The lower part of the bean cup 2 is snapped into the connecting bracket 12. A second air outlet 13, connecting to the inner cavity of the main body 1, is provided in the middle of the connecting bracket 12. A first air outlet 313, connecting to the heating chamber 311, is provided at the upper part of the heating upper shell 31. The first air outlet 313 is connected to the second air outlet 13. Figure 11 As shown, the centrifugal impeller 33 rotates, and external air first enters the main body 1 through each of the first air inlets 11, and then enters the airflow chamber 321 through the second air inlet 325 and the third air inlet 3261 respectively. After being heated, it is blown into the bean cup 2 through the second air outlet 13. The air intake is increased by the third air inlet 3261, and the inclined arrangement of the second air inlet 325 and the third air inlet 3261 creates a vortex during air intake, increasing the air intake speed and further increasing the air intake volume.

[0053] Specifically, such as Figure 5 As shown, an upper sealing ring 14 extends downward from the inner edge of the second air outlet 13. An upper connecting ring 15 is provided around the upper sealing ring 14. A protective connecting cylinder 314 is formed in the first air outlet 313. A lower connecting groove 3141 is provided on the upper part of the protective connecting cylinder 314. The upper connecting ring 15 is inserted into the lower connecting groove 3141. A connecting sealing ring 16 is provided between the inner wall of the upper sealing ring 14 and the lower connecting groove 3141. The connecting sealing ring 16 is sealed to the bean cup 2. The main unit 1 is connected to the heating shell 3 by inserting the upper connecting ring 15 into the lower connecting groove 3141. The upper and lower end faces of the connecting sealing ring 16 seal the main unit 1 and the heating shell 3. The inner ring of the connecting sealing ring 16 seals the main unit 1 and the bean cup 2. This simplifies the structure, reduces the number of sealing rings, improves the sealing performance, and reduces costs.

[0054] Specifically, such as Figures 6 to 8 As shown, a protective mesh 315 is provided inside the protective connecting cylinder 314. Multiple outwardly protruding limiting protrusions 3151 are spaced at intervals along the outer edge of the protective mesh 315 in the circumferential direction. Multiple limiting grooves 3142, corresponding to the limiting protrusions 3151, are spaced at intervals along the inner wall of the protective connecting cylinder 314 in the circumferential direction. The limiting protrusions 3151 and the limiting grooves 3142 are mutually limiting and engaged. A fixing pin 316 is installed on the side wall of each limiting groove 3142. A protective step 3143 is provided at the lower part of the inner wall of the protective connecting cylinder 314. The protective mesh 315 is clamped and fixed between each fixing pin 316 and the protective step 3143. After disassembling the bean cup 2, the protective mesh 315 blocks the second air outlet 13, preventing impurities from entering the heating shell 3 from the second air outlet 13 and improving safety. During production and assembly, each limiting protrusion 3151 is aligned with each limiting groove 3142, and the protective net 315 is inserted into the protective connecting cylinder 314 until the protective net 315 abuts against the protective step 3143. Finally, the fixing pin 316 is inserted so that the fixing pin 316 extends radially into each limiting groove 3142, thereby clamping and fixing the protective net 315 between each fixing pin 316 and the protective step 3143. The assembly process is simple and the production efficiency is high.

[0055] Specifically, such as Figure 10 As shown, the fixed support frame 44 includes multiple mica plates 441 that are cross-connected and fixed in the middle. A sensing support plate 442 extends upward from the middle of the upper mica plate 441. The sensing support plate 442 extends out of the upper mica plate 41 toward the bean cup 2. A temperature sensor 5 is fixedly installed on the upper part of the upper mica plate 41. The temperature sensor 5 is electrically connected to the control device. The distance between the temperature sensor 5 and the bean cup 2 is 5-8mm. Traditional temperature sensors 5 are fixed to the heating shell 3 by making a hole in it. This results in a relatively long distance between the temperature sensor 5 and the bean cup 2, leading to inaccurate temperature sensing and susceptibility to the temperature of the heating shell 3 itself, causing inaccurate baking temperature control. In this invention, the temperature sensor 5 is positioned below the bean cup 2, and its installation height is increased by the induction support plate 442. This brings the temperature sensor 5 closer to the bean cup 2, shortening the distance between them. Simultaneously, the temperature sensor 5 does not contact the bean cup 2 or the heating shell 3, preventing heat conduction interference and improving the accuracy of temperature detection within the bean cup 2. This results in more precise temperature control and improved baking performance. Furthermore, the lead wire of the temperature sensor 5 passes downwards from the center of the heating mechanism 4, where the temperature is relatively low, minimizing its impact on the lead wire. The temperature sensor 5 is a thin-film temperature sensor.

[0056] Specifically, such as Figures 6 to 8As shown, a wire groove 3222 is provided on one side of the flange 322 of the lower heating shell 32. A wire hole 317 is provided on the upper heating shell 31 at the position corresponding to the wire groove 3222. The lead wire of the fuse 46 passes downward through the lower mica plate 43, connects to the open-type thermostat 45 and the fuse 46, and then passes through the wire groove 3222 and the wire hole 317 in sequence to be electrically connected to the control device. The wire groove 3222 and / or the wire hole 317 are filled with heat-resistant sealant. The lead wire of the temperature sensor 5 passes downward through the center of the heating mechanism 4 and then passes through the wire groove 3222 and the wire hole 317 together with the lead wire of the heating mechanism 4 to be electrically connected to the control device, shortening the wiring distance. The wire groove 3222 and the wire hole 317 are filled and sealed with heat-resistant sealant to improve the sealing performance.

[0057] Specifically, such as Figures 2 to 4As shown, the bean cup 2 includes a baking inner liner 21, an insulated cup body 22, and a sealing lid 23. The baking inner liner 21 is fixedly installed inside the insulated cup body 22. The lower part of the insulated cup body 22 is snapped to the upper part of the main body 1. The sealing lid 23 covers the upper part of the insulated cup body 22. The sealing lid 23 includes an upper lid 231 and a lower lid 232. The upper lid 231 and the lower lid 232 are snapped together. The upper lid 231 opens downwards and has an upper annular chip baffle 2311 inside. The lower lid 232 has a central opening. The mounting hole 2321 has an inner edge extending upwards to form a lower annular chip baffle 2322. An annular chip collection groove 2323 is formed between the lower annular chip baffle 2322 and the inner wall of the lower cover 232. The lower end of the upper annular chip baffle 2311 is inserted into the chip collection groove 2323. An annular filter screen 233 is provided between the upper annular chip baffle 2311 and the inner wall of the upper cover 231. Multiple exhaust holes 2312 are provided circumferentially on the upper part of the upper cover 231 corresponding to the positions of the annular filter screen 233. The upper annular chip baffle 2321... A first exhaust gap 234 is formed between the upper annular chip baffle 2311 and the lower annular chip baffle 2322; a second exhaust gap 235 is formed between the upper annular chip baffle 2311 and the bottom of the chip collection groove 2323; a third exhaust gap 236 is formed between the upper annular chip baffle 2311 and the inner wall of the lower cover 232; the first exhaust gap 234 communicates with the baking inner liner 21; the second exhaust gap 235 communicates with the first exhaust gap 234; and the third exhaust gap 236 communicates with each exhaust hole 2312 through the inner cavity of the upper cover 231. Located above the heating mechanism 4, the lower part of the baking inner liner 21 is provided with multiple baking heating holes. The upper part of the baking inner liner 21 protrudes from the upper end face of the insulated cup body 22 and is inserted into the mounting hole 2321. A side handle 221 is provided on one side of the insulated cup body 22, and an upper handle 2313 is provided on the upper part of the upper cover 231. Two anti-rotation protrusions are provided on the upper end face of the insulated cup body 22, and two anti-rotation grooves corresponding to the anti-rotation protrusions are provided on the lower end face of the lower cover 232. The two anti-rotation protrusions are respectively inserted into the two anti-rotation grooves. The insulated cup body 22 and the sealing cup lid 23 are connected by the anti-rotation protrusions and anti-rotation grooves, which facilitates opening and closing the lid and prevents the sealing cup lid 23 from rotating during baking.

[0058] like Figure 11As shown, during roasting, the insulated cup body 22 of the bean cup 2 is snapped onto the connecting bracket 12 of the main body 1. The bottom of the roasting liner 21 is sealed to the heating shell 3 via the connecting sealing ring 16. The heating mechanism 4 and the drive motor 34 are activated to roast the beans. Hot air enters the roasting liner 21 through the roasting heating hole from the second air outlet 13, and the coffee beans are heated and roasted. During the roasting process, coffee beans produce skins. These skins are blown upwards with the hot air to the first exhaust gap 234, then through the second exhaust gap 235 into the third exhaust gap 236. At this time, the skins are blocked and filtered by the annular filter 233 and fall back into the chip collection groove 2323, while the hot air passes through the annular filter 233 and is discharged through each exhaust hole 2312. After roasting, disassemble the bean cup 2, open the sealing lid 23, and pour out the coffee beans. Since the upper edge of the roasting inner liner 21 is higher than the insulated cup body 22, it facilitates precise pouring of the coffee beans, preventing splashing during pouring, and also increases the contact area with the sealing lid 23. When cleaning the chaff, the chaff collection groove 2323 is exposed by disassembling the upper cover 231, making cleaning easier. The coffee beans and chaff are automatically separated during roasting, making it convenient to use, easy to clean, and with a simple structure and low cost.

[0059] When cooling coffee beans, the heating device is not working, but the drive motor 34 is working and blowing out cold air. The cold air forms a meandering exhaust channel in the sealed cup lid 23 through the first exhaust gap 234, the second exhaust gap 235 and the third exhaust gap 236, thereby increasing the length of the exhaust channel. During cooling, the time and path of the cold air flowing through the sealed cup lid 23 can be extended, thereby increasing the cooling speed of the sealed cup lid 23.

[0060] The above description is only a preferred embodiment of this utility model. For those skilled in the art, there will be changes in the specific implementation method and application scope based on the idea of ​​this utility model. The content of this specification should not be construed as a limitation of this utility model.

Claims

1. A household coffee roaster with an improved heating structure, comprising a main body (1) and a bean cup (2) movably mounted on the upper part of the main body (1), wherein the main body (1) is provided with a heating device and a control device, the heating device comprising a heating shell (3), a heating mechanism (4), a centrifugal impeller (33) and a drive motor (34), the heating mechanism (4) being disposed within the heating shell (3), the centrifugal impeller (33) being rotatably mounted within the heating shell (3) and located below the heating mechanism (4), and the drive motor (34) being fixedly mounted on the lower part of the heating shell (3) and connected to the centrifugal impeller (33) for transmission, characterized in that: The heating mechanism (4) includes an upper mica plate (41), a middle heat insulation frame (42), a lower mica plate (43), a fixed support frame (44), an open thermostat (45), a fuse (46), and at least one spiral heating wire (47). The spiral heating wire (47), the open thermostat (45), and the fuse (46) are connected in series with leads and electrically connected to the control circuit. The lower part of the fixed stand (44) is fixedly installed on the upper part of the middle heat insulation frame (42), the upper mica plate (41) is fixedly installed on the upper part of the fixed stand (44), the lower mica plate (43) is fixedly installed on the lower part of the middle heat insulation frame (42), the spiral heating wire (47) is installed around the side of the fixed stand (44) and is located between the upper mica plate (41) and the middle heat insulation frame (42), and the open thermostat (45) and the fuse (46) are respectively installed on the lower mica plate (43).

2. The household coffee roaster with an improved heating structure according to claim 1, characterized in that: The middle layer heat insulation frame (42) includes a heat insulation board (421) and multiple heat insulation support columns (422). The upper end of each heat insulation support column (422) is fixedly connected to the bottom surface of the heat insulation board (421), and the lower end of each heat insulation support column (422) is fixedly connected to the top surface of the lower layer mica board (43). A heat insulation gap (48) is formed between the heat insulation board (421) and the lower layer mica board (43). The heating shell (3) includes a heating upper shell (31), a heating lower shell (32), a heating sealing ring (327), and a heat-insulating mica sheet (328). The upper edge of the heating lower shell (32) is provided with a flange (322), and the outer edge of the flange (322) extends outward to form a mounting ring (3221). The lower edge of the heating upper shell (31) is fixedly connected to the mounting ring (3221) by screws. The mounting ring (3221) is fixedly connected to the main body (1) by screws. The lower part of the inner wall of the heating upper shell (31) is provided with a mounting step (312), and the lower mica sheet (43) is clamped and fixed to the mounting step (312). Between the flange (322), the heat-insulating mica sheet (328) is disposed on the inner wall of the heating upper shell (31) and located on the periphery of the spiral heating wire (47). The heating sealing ring (327) is disposed between the outer side of the flange (322) and the inner wall of the heating upper shell (31). The heating upper shell (31) is provided with a heating cavity (311) inside, and the heating lower shell (32) is provided with an airflow cavity (321) inside. The heating mechanism (4) is disposed in the heating cavity (311), and the centrifugal fan (33) is rotatably installed in the airflow cavity (321). Both the heating upper shell (31) and the heating lower shell (32) are made of plastic material.

3. A household coffee roaster with an improved heating structure according to claim 2, characterized in that: The lower mica plate (43) is provided with a plurality of lower air passage holes (431) that pass through the lower mica plate (43) at intervals along the circumferential direction. The upper mica plate (41) is provided with a plurality of upper air passage holes (411) at intervals along the circumferential direction. The outer diameter of the upper mica plate (41) is smaller than the outer diameter of the lower mica plate (43). The spiral heating wire (47) is located above the lower air passage holes (431) and is located in the middle of the heating cavity (311) along the axial direction. The open-type thermostat (45) and the fuse (46) are respectively fixedly installed on the bottom surface of the lower mica plate (43) by hollow rivets and located inside each lower air passage (431). Each hollow rivet is provided with a sealing plug (49).

4. A household coffee roaster with an improved heating structure according to claim 3, characterized in that: There is an exhaust gap (35) between the outer edge of the centrifugal impeller (33) and the inner wall of the heating lower shell (32). The lower air passage (431) is located above the exhaust gap (35). The width a of the lower air passage (431) in the radial direction is less than the maximum width b of the exhaust gap (35). The width of the exhaust gap (35) is 7-9 mm.

5. A household coffee roaster with an improved heating structure according to claim 2, characterized in that: The lower part of the heating lower shell (32) is provided with a motor mounting groove (323) with the opening facing downward. The drive motor (34) is fixedly installed in the motor mounting groove (323). The output shaft of the drive motor (34) passes through the heating lower shell (32) and is connected to the centrifugal impeller (33). The upper part of the motor mounting slot (323) is provided with a plurality of motor heat dissipation holes (324) that communicate with the airflow cavity (321) at intervals along the circumferential direction. The lower part of the main body (1) is provided with a plurality of first air inlets (11), and the periphery of the motor mounting slot (323) is provided with a plurality of second air inlets (325) that communicate with the airflow chamber (321) at intervals along the circumferential direction. An air inlet rib (326) is formed between two adjacent second air inlets (325) and is inclined in the radial direction. A third air inlet (3261) is provided through the air inlet rib (326). The upper part of the main body (1) is provided with a connecting card seat (12), the lower part of the bean cup (2) is snapped to the connecting card seat (12), the middle part of the connecting card seat (12) is provided with a second air outlet (13) that communicates with the inner cavity of the main body (1), the upper part of the heating shell (31) is provided with a first air outlet (313) that communicates with the heating cavity (311), and the first air outlet (313) is connected to the second air outlet (13).

6. A household coffee roaster with an improved heating structure according to claim 5, characterized in that: An upper sealing ring (14) extends downward from the inner edge of the second air outlet (13). An upper connecting ring (15) is provided around the upper sealing ring (14). A protective connecting cylinder (314) is formed in the first air outlet (313). A lower connecting groove (3141) is provided on the upper part of the protective connecting cylinder (314). The upper connecting ring (15) is inserted into the lower connecting groove (3141). A connecting sealing ring (16) is provided between the inner walls of the upper sealing ring (14) and the lower connecting groove (3141). The connecting sealing ring (16) is sealed and fitted with the bean cup (2).

7. A household coffee roaster with an improved heating structure according to claim 6, characterized in that: The protective connecting cylinder (314) is provided with a protective net (315). The outer edge of the protective net (315) is provided with a plurality of outwardly protruding limiting protrusions (3151) at intervals along the circumferential direction. The inner wall of the protective connecting cylinder (314) is provided with a plurality of limiting grooves (3142) at intervals along the circumferential direction, which are respectively corresponding to the limiting protrusions (3151). The limiting protrusions (3151) and the limiting grooves (3142) are mutually limiting and cooperating. Each limiting groove (3142) is provided with a fixing pin (316) on its side wall. The lower part of the inner wall of the protective connecting cylinder (314) is provided with a protective step (3143). The protective net (315) is clamped and fixed between each fixing pin (316) and the protective step (3143).

8. A household coffee roaster with an improved heating structure according to claim 1, characterized in that: The fixed support frame (44) includes multiple mica plates (441) that are cross-connected and fixed in the middle. A sensing support plate (442) extends upward from the middle of the upper mica plate (441). The sensing support plate (442) extends out of the upper mica plate (41) toward the bean cup (2). A temperature sensor (5) is fixedly installed on the upper part of the upper mica plate (41). The temperature sensor (5) is electrically connected to the control device. The distance between the temperature sensor (5) and the bean cup (2) is 5-8 mm.

9. A household coffee roaster with an improved heating structure according to claim 2, characterized in that: A wire groove (3222) is provided on one side of the flange (322) of the lower heating shell (32). A wire hole (317) is provided on the upper heating shell (31) corresponding to the wire groove (3222). The lead wire of the fuse (46) passes downward through the lower mica plate (43) to connect the open thermostat (45) and the fuse (46), and then passes through the wire groove (3222) and the wire hole (317) in sequence to be electrically connected to the control device. The wire groove (3222) and / or the wire hole (317) are filled with heat-resistant sealant.

10. A household coffee roaster with an improved heating structure according to any one of claims 1 to 9, characterized in that: The bean cup (2) includes a baking inner liner (21), an insulated cup body (22), and a sealing cup lid (23). The baking inner liner (21) is fixedly installed inside the insulated cup body (22). The lower part of the insulated cup body (22) is snapped to the upper part of the main body (1). The sealing cup lid (23) is placed on the upper part of the insulated cup body (22). The sealing cup lid (23) includes an upper lid body (231) and a lower lid body (232). The upper lid body (231) and the lower lid body (232) are snap-fitted together. The upper lid body (231) opens downwards and is provided with an upper annular chip baffle (2311). The lower lid body (232) has a mounting hole (2321) in the center. The inner edge of the mounting hole (2321) extends upwards to form a lower annular chip baffle (2322). An annular chip collection groove (2323) is formed between the lower annular chip baffle (2322) and the inner wall of the lower lid body (232). The lower end of the upper annular chip baffle (2311) is inserted into the chip collection groove (2323). An annular filter screen (233) is provided between the upper annular chip baffle (2311) and the inner wall of the upper lid body (231). The upper part of the cover (231) is provided with multiple exhaust holes (2312) along the circumferential direction corresponding to the position of the annular filter (233). A first exhaust gap (234) is formed between the upper annular chip baffle (2311) and the lower annular chip baffle (2322). A second exhaust gap (235) is formed between the upper annular chip baffle (2311) and the bottom of the chip collection groove (2323). A third exhaust gap (236) is formed between the upper annular chip baffle (2311) and the inner wall of the lower cover (232). The first exhaust gap (234) is connected to the baking liner (21). The second exhaust gap (235) is connected to the first exhaust gap (234). The third exhaust gap (236) is connected to each exhaust hole (2312) through the inner cavity of the upper cover (231). The baking liner (21) is located above the heating mechanism (4). The lower part of the baking liner (21) is provided with multiple baking heating holes. The upper part of the baking liner (21) protrudes from the upper end face of the heat-insulating cup body (22) and is inserted into the mounting hole (2321). A side handle (221) is provided on one side of the insulated cup body (22), and an upper handle (2313) is provided on the upper part of the upper cover (231); The upper end face of the heat-insulating cup body (22) is provided with two anti-rotation protrusions, and the lower end face of the lower cover (232) is provided with two anti-rotation grooves corresponding to the anti-rotation protrusions. The two anti-rotation protrusions are respectively inserted into the two anti-rotation grooves.

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