Roasting equipment

Abstract

We provide a roasting device that employs a hot air method and can roast several kilograms of coffee beans at once. [Solution] A roasting apparatus comprising: a cylindrical body made of carbon material constituting a roasting chamber for roasting coffee beans; a blower supplying an airflow to raise the coffee beans from the bottom of the roasting chamber; a first heater for heating the air from the blower; and a second heater for heating the peripheral wall of the cylindrical body, wherein the cylindrical body is fixed upright, and the cross-sectional area (S1) of the upper part of the roasting chamber is larger than the area (S2) of the bottom. The inner wall surface of the roasting chamber may be inclined such that the cross-sectional area increases along the height direction from the bottom, or it may be composed of a combination of a tapered section whose inner diameter increases upward in the height direction from the bottom and a cylindrical section fixed at the maximum inner diameter of the tapered section.

Description

Technical Field

[0001] The present invention relates to a hot air roasting apparatus for coffee beans.

Background Art

[0002] As a small-scale roasting apparatus for coffee beans used in homes or cafes, a small roasting apparatus in which coffee beans are stirred in hot air is generally used. Such a roasting apparatus incorporates a hot air fluidized bed chamber, and heated air is fed in with sufficient force to lift the coffee beans within the fluidized bed chamber. As the beans tumble and circulate within this fluidized bed, heat is transferred to the beans, thereby roasting them.

[0003] As such a roasting apparatus, for example, in Japanese Patent No. 4847622 (Patent Document 1), a roasting apparatus is proposed that uses a combination of a blower and an electric heater as hot air generating means, and injects the generated hot air into a roasting chamber (roasting container) through a nozzle. In this document, the roasting chamber is fixed, and the beans in the roasting chamber are circulated by the hot air flow. By constructing the roasting chamber with heat-resistant glass, the state of the beans in the roasting chamber can be observed.

[0004] Also, in Japanese Patent No. 6679302 (Patent Document 2), it is proposed to arrange an infrared sensor outside a glass roasting container and detect the temperature of the roasting object itself by receiving infrared rays from the roasting object, and control the temperature of the heating means (heater).

[0005] Furthermore, in Japanese Patent Application Laid-Open No. 2022-537527 (Patent Document 3), in a roasting apparatus including a chamber, an air flow driver, and an electric heater disposed below a bottom opening of the chamber, a conduit for propelling a hot air flow from the heater to the bottom opening of the roasting chamber is provided, the conduit includes a local transverse constriction that reduces the cross-section of the conduit to a minimum cross-section, and at least one temperature probe is disposed at the minimum cross-section of the conduit. A roasting apparatus is proposed. Here, the air driver is a motor-driven fan, and the generated airflow is configured to heat and agitate the beans as it rises. A heater is operable to heat the airflow generated by the airflow driver. In a specific embodiment, the heater is positioned between the fan and the bottom opening of the chamber and is heated before the airflow enters the chamber, thereby lifting the beans. (0044) The constricted section forces various heterogeneous flows to mix, resulting in the airflow having the same temperature in all other sections of the constricted section. Consequently, the constricted section homogenizes the airflow, and the airflow and temperature measured by the probe in the constricted section accurately reflect the temperature of the hot air flow supplied to the bottom of the chamber, and can be reliably used in the heating control feedback loop (

[0051] ). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 4847622 [Patent Document 2] Patent No. 6679302 [Patent Document 3] Special table number 2022-537527 [Patent Document 4] Japanese Patent Publication No. 2025-036818 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The hot air heating method proposed in Patent Documents 1-3 controls the temperature inside the roasting chamber by controlling the heater temperature. The roasting chamber is made of a glass container with low thermal conductivity, and furthermore, the beans are stirred by a heated airflow. Therefore, in terms of energy costs to generate enough hot air for heating and stirring during roasting, this method is limited to roasting equipment that roasts enough beans for a few cups, such as in homes or cafes.

[0008] This invention was made in view of the above circumstances, and its purpose is to provide a technology that can be applied to roasting equipment that employs a hot air method and is capable of roasting several kilograms of coffee beans at once. [Means for solving the problem]

[0009] The inventors of this invention have conducted various studies on a roasting apparatus that can heat and stir coffee beans using hot air. In conventional hot-air roasting equipment, which blows hot air from the bottom of the roasting chamber, scaling up the system results in insufficient agitation of the beans by the airflow, leading to a decrease in the homogeneity of the roasted beans. The inventors have discovered that a tornado flow can be generated by hot air from the bottom and air blown from the sides to agitate coffee beans, and have filed a patent application (Patent Document 4). However, the amount of energy required to generate a tornado flow sufficient for agitation is large, posing a challenge in terms of energy cost.

[0010] The inventors, after further investigation, arrived at the present invention. Specifically, the roasting apparatus of the present invention has the following characteristics. [1] A cylindrical body made of carbon material that constitutes a roasting chamber for roasting coffee beans; A roasting apparatus comprising: a blower that supplies an airflow to raise the coffee beans from the bottom of the roasting chamber; a first heater that heats the air from the blower; and a second heater that heats the peripheral wall of the cylindrical body, The cylindrical body is fixed upright, and the roasting apparatus has a cross-sectional area (S1) at the top of the roasting chamber that is larger than the area (S2) at the bottom.

[0011] [2] The roasting apparatus according to embodiment 1, wherein the inner wall surface of the roasting chamber is inclined such that the cross-sectional area increases along the height direction from the bottom surface. [3] The roasting apparatus according to embodiment 1, wherein the roasting chamber is composed of a combination of a tapered section whose inner diameter increases from the bottom upward in the height direction and a cylindrical section fixed at the maximum inner diameter of the tapered section.

[0012] [4] The roasting apparatus according to embodiment 1 or 2, wherein the second heater is attached to the peripheral wall of the cylindrical body. [5] The roasting apparatus according to embodiment 4, wherein the second heater is a stick-type heater and is housed in the periphery wall of the roasting chamber along the height direction of the roasting chamber. [6] The roasting apparatus according to any one of embodiments 1 to 5, wherein the upper end of the roasting chamber is provided with a powder separation means for separating the coffee bean dust generated by roasting. [7] The roasting apparatus according to embodiment 1, wherein the second heater is a band heater installed so as to cover the outer surface of the cylindrical body. [8] The roasting apparatus according to embodiment 1, wherein the normal airflow of the blower can be controlled to decrease from the initial stage of roasting to the later stage of roasting. [Effects of the Invention]

[0013] According to the roasting apparatus of the present invention, when the cross-sectional area above the roasting chamber through which the hot air passes increases, the pressure of the hot air that raises the coffee beans decreases, causing a lateral flow, and thus the coffee beans circulate. Moreover, since the perimeter wall of the roasting chamber is made of a carbon material with excellent thermal conductivity, the beans can be exposed to far-infrared rays by coming into contact with the perimeter wall as they move from top to bottom. By using far-infrared exposure and hot air together, roasting is performed efficiently, and since far-infrared rays can directly heat the inside of the multilayer structure of the coffee beans, even when roasting large quantities of coffee beans exceeding 1 kg, the variation in roasting degree between batches is kept small. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram showing the configuration of one embodiment (Embodiment 1) of the roasting chamber used in the roasting apparatus of the present invention, where (A) is a top view and (B) is a cross-sectional view. [Figure 2] This is a schematic diagram showing the configuration of another embodiment of the roasting chamber used in the roasting apparatus of the present invention, where (A) is a top view and (B) is a cross-sectional view. [Figure 3]It is a schematic diagram showing the configuration of another embodiment of the roasting chamber used in the roasting apparatus of the present invention, (A) is a top view, and (B) is a cross-sectional view. [Figure 4] It is a schematic diagram showing the configuration of an example of a cartridge type heater. [Figure 5] It is a block diagram showing the configuration of an embodiment of a roasting apparatus provided with the roasting section of the embodiment shown in FIG. 1. [Figure 6] It is a schematic diagram showing the configurations of Roasting Chambers No. 1 to No. 4 evaluated in the examples. [Figure 7] It is a (A) top schematic view and (B) cross-sectional schematic view showing the configuration of Roasting Chamber No. 5 used in the examples. [Figure 8] It is a longitudinal cross-sectional view schematically showing the configuration of Embodiment 2. [Figure 9] It is a graph showing the time-dependent changes in the heating temperatures of the first and second heaters, and the temperatures of the cylindrical body and the coffee beans in Embodiment 1. [Figure 10] It is a graph showing the time-dependent changes in the heating temperatures of the first and second heaters, and the temperatures of the cylindrical body and the coffee beans in Embodiment 2.

Mode for Carrying Out the Invention

[0015] The roasting apparatus of the present invention includes a cylindrical body made of a carbon material that constitutes a roasting chamber for roasting coffee beans; a blower that supplies an upward airflow for raising the coffee beans from the bottom of the roasting chamber; a first heater that heats the air from the blower; and a second heater that heats the peripheral wall of the cylindrical body, and the cylindrical body is fixedly erected, and the cross-sectional area (S1) of the upper part of the roasting chamber is larger than the cross-sectional area (S2) of the bottom.

[0016] (Embodiment 1) First, the roasting chamber, which is the main body of the roasting apparatus of the present invention, will be described based on FIGS. 1 to 3.

[0017] The roasting chamber used in the roasting apparatus of the present invention is composed of a cylindrical body made of carbon material, and is erected and fixed in the height direction of the cylindrical body, with the inside of the cylindrical body serving as the roasting chamber. Airflow sent out from a blower is blown in from the bottom surface of the cylindrical body, creating an upward airflow that circulates the coffee beans inside the roasting chamber.

[0018] The type of carbon material used to construct the cylindrical body is not particularly limited, but the bulk density should be 1.2 to 2.2 g / cm³. 3 Preferably, 1.3 to 2.0 g / cm³ 3 , more preferably 1.5 to 1.9 g / cm³ 3 It is preferable that the material be composed of carbon material. Furthermore, the thermal conductivity at 25°C is preferably 60 W / m·K or higher, preferably 80 W / m·K or higher, and more preferably 100 W / m·K or higher, with an upper limit of usually 200 W / m·K or lower.

[0019] Examples of such carbon materials include graphite, carbon fiber reinforced carbon composites (CC composites), glassy carbon (non-graphitized carbon obtained by carbonizing thermosetting resins such as phenolic resins), and porous carbon (porous carbon graphite). Of these, graphite and CC composites are preferred, and graphite is more preferred. As for graphite, natural graphite, artificial graphite, charcoal, pitch, and carbides of synthetic resins can be used. Furthermore, the inner and outer walls of the cylindrical body may be coated as needed with ceramic coatings such as alumina, silica, or zirconia, glass coatings, glassy carbon coatings, polysiloxane-based heat-resistant coatings, or pyrolytic carbon graphite coatings.

[0020] The shape of the cylindrical body is such that the cross-sectional area (S1) is larger than the area (S2) of the bottom surface of the roasting chamber. The cross-sectional area S1 can be any cross-section from the middle to the top of the cylindrical body in the height direction. Air blown in through the small area (S2) bottom surface passes through the large area (S1) cross-sectional area, causing the airflow to spread towards the wall surface of the cylindrical body which is the roasting chamber, and the rising air pressure decreases. As a result, the coffee beans pushed up by the rising airflow are transported to the wall surface of the cylindrical body and descend along the wall surface. In other words, circulation of coffee beans within the roasting chamber is achieved. The shape of the cylindrical body is such that the cross-sectional area of ​​the roasting chamber increases uniformly from the bottom surface upwards (when any two points are m and n (m is above n), the cross-sectional area S m ≥S n It is preferable that the following conditions be met.

[0021] The shape of the cylindrical body and the roasting chamber inside the cylindrical body only needs to satisfy the above requirements. Typical forms of the cylindrical body and roasting chamber are shown in Figures 1 to 3. The cylindrical body and roasting chamber can be manufactured by cutting a block of artificial graphite, which has been pre-formed into the desired shape, to the specified dimensions. If composed of CC composite, the necessary processing may be performed after thermosetting the composite material, or the necessary processing may be performed in a semi-cured state, followed by complete curing to impart the desired shape.

[0022] In the embodiment shown in Figure 1, the roasting chamber, which is formed by the internal structure of the cylindrical body 1, is composed of a combination of a tapered section 1a that expands in diameter from the bottom surface (area S2, inner diameter D2) upwards to the inner diameter D1 of a cross-section with area S1, and a cylindrical section 1b whose inner diameter is constant at D1. The cylindrical section 1b and the tapered section 1a may be formed by machining the inside of the cylindrical body, or the tapered section 1a and the cylindrical section 1b may be formed separately and joined together integrally. A cylindrical section may be further provided below the tapered section 1a, or a tapered section may be further provided above the cylindrical section 1b, or there may be no cylindrical section and multiple tapered sections with different angles may be provided, and the longitudinal cross-sectional contour of the tapered section (including the taper described later) may be curved.

[0023] Furthermore, it is preferable that the tapered portion 1b be at least 1 / 3 of the cylindrical body. That is, it is preferable that the ratio of the height t of the tapered portion 1b to the height T of the cylindrical body 1 be at least 1 / 3 of T. If the ratio of the tapered portion 1b is too small, the circulation of the coffee beans, as described later, will be reduced, and the far-infrared effect will be insufficient. There is no particular upper limit set for the tapered portion 1b; it may be 2 / 3 or less of the cylindrical body, or 40-60% of the cylindrical body, etc.

[0024] Furthermore, in the embodiment shown in Figure 2, the inside of the cylindrical body 2 made of carbon material is tapered, with the inner diameter increasing from the bottom surface to the top surface. The bottom surface of the inside of the cylindrical body 2 (roasting chamber 2A) has an inner diameter D2 and an area S2, while the upper end surface of the roasting chamber has an inner diameter D1 which is larger than the inner diameter D2 and an area S1 which is larger than the area S2.

[0025] Areas S1 and S2 are not particularly limited, but preferably the area ratio of S2 to S1 (S2 / S1) is 1.3 to 10, more preferably 1.5 to 3. As a result, as shown by the arrows in Figures 1 to 3, the rising airflow blown in through the bottom surface of the roasting chamber (area S2) passes through the large area (S1), causing the air pressure to decrease and the upward force on the beans to decrease, thereby creating a circulating flow that causes the lifted beans to descend.

[0026] The angle of the tapered section or taper (vertical cross-sectional contour) with respect to the horizontal direction (upper surface of the holding plate 20) is set appropriately through hot air pressure simulation, testing, etc., but can be, for example, 95-120°, 97-110°, or 99-103°. Note that the smaller the angle with respect to the horizontal direction, the lower the average thickness of the cylindrical body can be, thereby reducing the weight of the cylindrical body and improving thermal efficiency, but the stirring effect will be reduced, so this should be taken into consideration when setting the angle.

[0027] On the bottom surface of the cylindrical body that forms the bottom of the roasting chamber, a holding plate 20 is attached, which has a number of holes sized such that an air flow blown in from the bottom surface can pass through, but coffee beans cannot pass through. The holding plate 20 is pivotally supported on the wall surfaces of the cylindrical bodies 1 and 2 so that it can be in a horizontal state (see FIG. 1) during roasting and can be moved to a tilted state in which the roasted product can fall after roasting. The constituent material of such a holding plate 20 is not particularly limited. It may be made of the same material (carbon material) as the cylindrical body 1 (or 2) that constitutes the roasting chamber 1A (or 2A), or it may be made of metal for ease of processing such as the attachment and removal of the cylindrical body 1 and the opening 31.

[0028] An inlet 30, which serves as an air inlet for blowing the air flow from the blower into the roasting chamber 1A, is connected to the bottom surface of the carbon material cylindrical body 1 that constitutes the roasting chamber 1A.

[0029] An outlet 31 for taking out the roasted beans is provided in the inlet 30, and a door that can be opened and closed is attached to the outlet 31 for taking out the roasted product transferred from the roasting chamber.

[0030] The inlet 30 may be made of a carbon material similar to the cylindrical body, or preferably made of a metal such as iron or SUS from the viewpoints of ease of processing such as the attachment of the cylindrical body 1 and the outlet 31 and strength.

[0031] The shape of the carbon material cylindrical body that constitutes the roasting chamber was a cylindrical body in the forms shown in FIGS. 1 and 2, but the shape of the roasting chamber used in the present invention is not limited to this. For example, in the form shown in FIG. 3, the cross-section is substantially semi-circular. From the radius L2 of the substantially semi-circular shape at the lower end to the radius L1 of the substantially semi-circular shape at the upper end, it has a taper that expands so as to satisfy the relationship S2 < S1 between the area S2 of the bottom surface and the area S1 of the upper end surface of the roasting chamber 3A inside the cylindrical body 3 with a semi-circular cross-section. In FIG. 3, the same reference numerals as in FIGS. 1 and 2 denote the same members, and the reference numerals with dashes denote the same functional members that differ only in shape.

[0032] Furthermore, the cylindrical body may be a rectangular prism, and the shape of the roasting chamber inside may be a triangle or trapezoid with a cross-section in the height direction. It is preferable that the cross-sectional shape of the roasting chamber be circular, as this ensures a constant distance from the inner surface of the cylindrical body, allowing the coffee beans to receive the effects of far-infrared rays more stably.

[0033] The cylindrical carbon material body that constitutes the roasting chamber is equipped with a second heater for heating the air inside the roasting chamber. The second heater may be attached to the wall surface of the cylindrical body that constitutes the roasting chamber, or electrodes may be attached so that the entire cylindrical carbon material body generates heat. In this embodiment, a rod-shaped heater is embedded in the peripheral wall that constitutes the cylindrical body.

[0034] The peripheral walls of the cylindrical bodies 1, 2, and 3 shown in Figures 1, 2, and 3 have through-holes 10 and 11 running through them along the height direction of the cylindrical bodies 1, 2, and 3. These through-holes 10 and 11 serve as housings for the second heater, which is a stick-type heater. There are six through-holes 10 and 11 that serve as housings for the stick-type heater, spaced equally apart in the circumferential direction.

[0035] The thickness of the walls of the cylindrical bodies 1, 2, and 3 (the walls of the cylindrical parts) is not particularly limited, but in this embodiment, it is usually 20 to 50 mm, preferably 20 to 30 mm. If it is too thin, it will be difficult to drill through holes 10 and 11 that will serve as the housings for the stick-type heaters. On the other hand, if it is too thick, the amount of heat required for heating will increase, so from an energy-saving standpoint, it is sufficient to have a thickness that is necessary and sufficient to provide the heater housings.

[0036] In the configurations shown in Figures 1, 2, and 3, six through-holes for housing stick-type heaters were provided on the peripheral wall surface, but the roasting chamber used in the present invention is not limited to this. Any number of heaters is sufficient to heat the entire cylindrical body made of carbon material almost uniformly and to emit far-infrared rays from the entire cylindrical body made of carbon material, and can be appropriately selected depending on the size and type of stick-type heater used.

[0037] The stick-type heater is not particularly limited, but for example, a cartridge-type heater 12 as shown in Figure 4 can be used.

[0038] The cartridge heater 12 shown in Figure 4 consists of a cylindrical heating element 12a, which generates heat when an electric current is applied (for example, a nichrome wire), inserted into a cylindrical outer tube 12b, with lead wires 12c extending outwards to supply power to the heating element. The lead wires 12c are brought out onto the upper surface of the cylindrical body 1.

[0039] Next, the roasting apparatus of the present invention will be described with reference to Figure 5. Figure 5 shows the configuration of one embodiment of a roasting apparatus equipped with the roasting chamber shown in Figure 1.

[0040] The roasting apparatus shown in Figure 5 comprises: a cylindrical body 1 made of carbon material with a roasting chamber 1A having the configuration shown in Figure 1; a blower 32 that generates an airflow to be blown into the roasting chamber 1A; a first heater 33 that heats the airflow; a stick-type second heater 12 embedded in the peripheral wall of the cylindrical body made of carbon material for heating the cylindrical body; an inlet 30 connected to the bottom of the roasting chamber 1A that serves as an inlet for blowing hot air to roast and circulate the coffee beans; and a separation means 40 connected to the upper end of the roasting chamber for collecting residue (mainly chaff) generated during roasting.

[0041] The airflow path from the blower 32 to the port 30a of the inlet 30 is equipped with a first heater (hot air generating heater) 33 for heating the airflow from the blower 32 and an airflow control valve 34 for adjusting the amount of air being blown in. The hot air generating heater 33 is preferably equipped with a temperature control means (temperature control controller: not shown). The temperature control means is preferably electrically or electronically connected to a temperature sensor (not shown) attached to the cylindrical body 1.

[0042] Furthermore, the roasting chamber may be equipped with a collection unit 36 ​​for collecting the roasted beans discharged from the roasted bean outlet 31 of the inlet, and may also be equipped with a suction device 35 for cooling the roasted beans collected in the collection unit 36. The blower 32 for supplying air to the roasting chamber 1A may also be used as a suction device for cooling the roasted beans. In this case, for example, a three-way switching valve that selectively switches to cool the roasted products may be placed between the blower 32 and the first heater 33, so that air is supplied to the hot air generating heater 33 side during roasting, and after roasting is finished, the heat from the collection unit 36 ​​side is sucked in and discharged.

[0043] The top surface of the cylindrical body 1 is closed by a lid 21. The lid 21 that closes the top surface of the cylindrical body 1 has an exhaust duct and an exhaust port 21a for discharging dust and roasting residue generated during roasting.

[0044] The separation means 40 is connected to an exhaust port 21a opened in the center of the lid 21 that closes the top surface of the roasting chamber, and includes a cyclone 42 for separating powder (chaff) mixed in the exhaust flow discharged from the exhaust port 21a, and a cock 44 for adjusting the exhaust flow rate and whether or not to exhaust. An intake fan that sends the exhaust flow to the cyclone 42 may be installed between the cyclone 42 and the cock 44.

[0045] The hopper 41 for supplying coffee beans to the roasting chamber may be attached to the lid 21, or it may be configured to be attached only when necessary. Furthermore, the cock 44 may be a lever that selectively switches between a supply passage communicating with the hopper 41 and an intake passage connected to the cyclone 42.

[0046] The lid 21 closes the top of the roasting chamber 1A, but a section corresponding to the heater housing 10 is left open, allowing lead wires 12c for heating the second heater (stick-type heater) housed in the heater housing 10 to be pulled out.

[0047] [How to use the roasting machine] Next, we will explain a method for roasting coffee beans using a roasting apparatus (Figure 5) equipped with a roasting chamber as shown in Figure 1. First, as shown in Figure 5, the cylindrical body 1 is heated by energizing the cartridge-type heater 12 with the holding plate 20 set in a horizontal position. Once the cylindrical body 1 has heated up to a predetermined temperature, the green coffee beans are supplied from the hopper 41 to the roasting chamber 1A.

[0048] A predetermined amount of green coffee beans is added, and the blower 32 and the first heater 33 are activated to blow hot air into the roasting chamber 1A. The amount of green beans can be set to 2 / 3 or less, 60% or less, of the volume of the roasting chamber 1A, taking into account the expansion of the coffee beans during roasting.

[0049] Hot air from the blower 32 passes through the inlet 30 and is blown into the roasting chamber 1A as an updraft from the bottom. Inside the roasting chamber 1A, the coffee beans are blown upwards by the incoming hot air (updraft). On the other hand, when the hot air passes through an area S1 that is larger than the cross-sectional area S2 of the inlet, the upward pressure of the updraft decreases and it spreads radially. The coffee beans are carried by the radially spread airflow to the peripheral wall surface of the cylindrical body 1. Then, by colliding with the peripheral wall surface, they descend along the peripheral wall surface of the cylindrical body. As they descend, they come into contact with the carbon material cylindrical body 1, so the beans receive far-infrared radiation from the heated carbon material.

[0050] Far-infrared rays, absorbed by coffee beans which are bulky, multi-layered masses, cause molecular vibrations (thermal effects) that allow them to heat to the core without excessively heating the surface. Therefore, by using both hot air and far-infrared heating, heating can be done efficiently, and the difference in heat energy received can be minimized, whether the amount of coffee beans is small or exceeding 1 kg. This helps to suppress variations in the degree of roasting of coffee beans roasted within the same batch.

[0051] Roasting conditions such as heating time (roasting time) and airflow (normal airflow) are set appropriately according to the configuration of the roasting apparatus and the type of product being roasted, including the type of coffee beans, the type of carbon material of the cylindrical body 1 that makes up the roasting chamber 1A, and the size of the cylindrical body 1.

[0052] By operating the cyclone 42 during roasting, air from the roasting chamber 1A is drawn in, and the cyclone 42 collects the green bean residue. This separates and removes chaff and other materials generated during roasting, thus reducing the effort required to clean the cylindrical body 1 after roasting and shortening the roasting interval. Furthermore, the degree to which the valve 44 is opened or closed allows for adjustment of the airflow rate and airflow force during roasting.

[0053] Once roasting is complete, the door of the inlet 30's outlet 31 is opened, and the holding plate 20 is tilted to allow the roasted beans in the roasting chamber to fall into the collection unit 36. The suction device 35 is then activated to cool the roasted beans by sucking out the heat from the collection unit 36.

[0054] In the roasting apparatus of the present invention having the above configuration, the roasting chamber 1A is configured so that the rising airflow is emitted upwards, allowing the coffee beans to circulate within the roasting chamber 1A. Furthermore, as the coffee beans descend, they are also heated by far-infrared rays from the cylindrical body 1 made of carbon material that constitutes the roasting chamber 1A, thus enabling efficient heating.

[0055] Therefore, conventionally, achieving sufficient roasting using only hot air required a large amount of energy for generating the hot air, which tended to hinder energy conservation. In this invention, the cylindrical body constituting the roasting chamber is also directly heated by the second heater, which prevents the air inside the roasting chamber from cooling down and also allows for efficient heating of the coffee beans to the inside using far-infrared rays. As a result, it becomes possible to roast coffee beans in quantities ranging from several hundred grams to several kilograms, which are the roasting units used by roasting bean manufacturers, at a practical level, not only for home or cafe use.

[0056] [Examples] The energy required to generate the updraft and circulating airflow necessary for bean agitation was compared based on the shape of the roasting chamber. The structures of roasting chambers No. 1 to No. 4 used are shown in Figure 6. No. 5 is a cylindrical body with the structure shown in Figure 7 in order to generate a tornado flow. Roasting chamber No. 5 shown in Figure 7 has four main passages 52 that penetrate the circumferential wall of the cylindrical body in the height direction of the cylinder, and communication holes 53 that are drilled radially in communication with each main passage. By blowing the airflow from the main passages 52 out through the communication holes 53, a tornado flow can be formed inside the roasting chamber. For No. 5, a larger blower capable of supplying a greater volume of air than those used in Nos. 1 to 4 was employed to generate a tornado flow.

[0057] The airflow and pressure inside the inlet duct were measured when roasting 5 kg of beans. The energy required for roasting was calculated by converting the amount of heat (joules) needed to heat the first heater, assuming a room temperature (20°C) and a roasting temperature (250°C), into electrical power (watts). Furthermore, a viewing window was created in the peripheral wall of a cylindrical body made of carbon material to observe the state of the beans during roasting (stirring condition). These results are shown in Table 1.

[0058] [Table 1]

[0059] In No. 3, by changing the position of the holding plate 20", the area S2 at the bottom of the roasting chamber and the cross-sectional area S1 at the top are equal. As a result, the rising airflow from the blower alone was not sufficient to agitate the beans during roasting. Even increasing the airflow pressure did not prevent the beans from accumulating at the bottom of the roasting chamber, making it difficult to circulate the beans within the chamber.

[0060] In No. 4, the holding plate 20" was set at an angle, making the area S2 of the air inlet larger than the cross-sectional area S1 of the upper part of the roasting chamber, which prevented sufficient stirring of the beans by circulation.

[0061] Roasting chamber No. 5 was able to circulate the beans within the chamber by generating a tornado flow, but generating this tornado flow required a larger blower than those used in chambers No. 1-4, requiring more than three times the energy needed for updrafts alone. Therefore, applying this to a roasting apparatus for commercial-grade beans (at least 1 kg or more) was unsuitable from an economic and energy standpoint.

[0062] In this regard, the roasting apparatus of the present invention, which is equipped with roasting chambers No. 1 and No. 2 in which the cross-sectional area S1 above the roasting chamber is larger than the area S2 below, was able to circulate the beans with the same amount of energy as cylindrical roasting chambers (No. 3, 4). In particular, in No. 1 (S2 = 0.5 × S1 and t = 0.5 × T), the amount of energy required was reduced to about half compared to cylindrical roasting chambers.

[0063] (Embodiment 2) This embodiment differs from Embodiment 1 in that, as shown in Figure 8, the second heater is a band heater 62 installed to cover (enclose) the outer surface of the cylindrical body 6. This embodiment also includes a cylindrical body temperature sensor 65 and a coffee bean temperature sensor 66. The cylindrical body temperature sensor 65 can detect the temperature of the inner wall surface of the cylindrical body, and the coffee bean temperature sensor 66 can detect the temperature of coffee beans in contact with the sensor. Other configurations common to Embodiment 1 are omitted from this description.

[0064] The airflow (normal airflow) of the blower can be controlled to decrease (lower airflow force) from the initial to the later stages of roasting. Coffee beans in the initial stages of roasting contain a lot of moisture and therefore have a high density, while coffee beans in the later stages of roasting have lost moisture and also expand due to cracking, resulting in a lower density. For this reason, if the airflow is always the same, the coffee beans in the initial stages of roasting may not be sufficiently agitated, or in the later stages of roasting, they may be blown above the top surface of the cylindrical container (slammed against the lid on top). By controlling the airflow as described above, the beans can be raised and agitated to the same height level, ensuring a uniform far-infrared effect. Airflow control can be performed using a program, for example, and can be adjusted according to the type of coffee beans, the amount added, and the desired roast level. Furthermore, a sensor may be provided to monitor the internal conditions of the cylindrical container, and the airflow may be changed based on the sensor signal. The sensor can detect temperature, humidity, coffee bean speed, odor, etc. In this embodiment, two temperature sensors 65 and 66 are provided.

[0065] In Embodiment 1 described above, the wall thickness of the cylindrical body (cylindrical portion) was 20 to 50 mm. However, in this embodiment, by using a band heater 62 that tightly covers the outer surface of the cylindrical body as the second heater, it becomes unnecessary to drill through holes 10 and 11 that serve as the housing for the stick-type heater, and the thickness can be reduced accordingly. The wall thickness of the cylindrical body (cylindrical portion) ((D4-D3) / 2 in Figure 8) only needs to be sufficient to maintain adequate strength, and can be 5 to 20 mm, 8 to 15 mm, etc. This reduces the amount of heat required to heat the cylindrical body and the weight of the cylindrical body. The band heater 62 is an example of a heater that tightly covers the outer surface of the cylindrical body, and other heaters may be used. The band heater 62 can be one that includes a heating element such as a nichrome wire, an insulator such as ceramic or mica, and an outer casing such as stainless steel.

[0066] Figures 9 and 10 show graphs illustrating the time-dependent changes in the heating temperatures of the first and second heaters, as well as the temperatures of the cylindrical body and coffee beans. Both cylindrical bodies were made by carving out black soot, and the dimensions (mm) and angles (°) of each part are as shown in Table 2 below. The angle is the angle between the tapered contour line in the longitudinal section and the upper surface of the retaining plate. The cylindrical body heights T1-10 are due to subtracting the thickness of the retaining plate. Other dimensions include the height T2 of the band heater 62, which is 290 mm, and the outer diameter D5 of the band heater, which is 310 mm. Table 3 shows the relationship between the temperature range of the hot air during roasting and the normal airflow rate.

[0067] [Table 2]

[0068] [Table 3]

[0069] As can be seen from Figure 9 of Embodiment 1 and Figure 10 of Embodiment 2, in Embodiment 1, which uses a stick-type heater as the second heater, the heating temperature of the second heater needed to be about 180-190°C higher to achieve the same surface temperature as the cylindrical body compared to Embodiment 2, which uses a band heater. As a result, the total output was 5400W in Embodiment 1 and 4000W in Embodiment 2. In addition, the weight of the product was significantly reduced to about 21kg in Embodiment 1 and about 7kg in Embodiment 2. Furthermore, visual inspection of the roasted beans revealed almost no color unevenness in either embodiment, although Embodiment 2 showed slightly less color unevenness.

[0070] Furthermore, when the cylindrical inner surface was heated by the second heater, the temperature distribution was measured using thermography. In Embodiment 1, the temperature was high near the stick heater and slightly lower in the intermediate region, showing an uneven distribution. However, in Embodiment 2, there was no unevenness in the temperature distribution.

[0071] Furthermore, by using programmatic control of the hot air volume (normal air volume) as shown in Table 3, it was possible to maintain a nearly constant coffee bean lift height from the initial to the final stages of roasting.

[0072] It should be noted that all disclosed embodiments are illustrative and can be modified as appropriate. For example, heaters other than stick-type heaters and band heaters may be used, and additional or alternative sensors may be provided. The size can also be modified as appropriate depending on the application (household, retail, manufacturing, etc.). [Industrial applicability]

[0073] The roasting apparatus of the present invention comprises a first heater that generates hot air and a second heater that directly heats the roasting chamber, and further utilizes the far-infrared effect from a cylindrical body made of carbon material that constitutes the roasting chamber. Therefore, it is possible to roast several hundred grams to several kilograms of coffee beans, which are the roasting units used by roasting manufacturers, at once at a practically acceptable energy cost.

[0074] By using hot air to agitate the beans and heating them by far-infrared rays as they come into contact with the cylindrical body wall made of carbon material during the bean circulation process, the roasting apparatus of the present invention can heat hundreds of grams to several kilograms, or even more, of coffee beans in a single batch to a nearly uniform degree. Therefore, the roasting apparatus of the present invention is useful not only for home and cafe use, but also for commercial use by various roasting manufacturers of all sizes, from small to large. [Explanation of symbols]

[0075] 1, 2, 3, 6 Carbon material cylindrical body 1A, 2A, 3A roasting room 10, 11, 11' Heater housing (through hole) 12. Stick-type heater (second heater) 20, 20' retaining plate 21 Lid 30, 30' inlet 31. Roasted Beans Dispenser 32 Blower 33 Heating means (first heater) 34. Airflow adjustment means (airflow adjustment valve) 35 Suction machine 36 Collection Department 40 Separation means 41 Hopper 42 Cyclone 50. Tubular body made of carbon material 51 Heater housing 52 Main passage (through passage) 53 Sub-channel (communication hole) 62 Band Heater 65 Cylindrical temperature sensor 66 Coffee Bean Temperature Sensor

Claims

1. A roasting apparatus comprising: a cylindrical body made of carbon material constituting a roasting chamber for roasting coffee beans; a blower supplying an airflow to raise the coffee beans from the bottom of the roasting chamber; a first heater for heating the air from the blower; and a second heater for heating the peripheral wall of the cylindrical body, The cylindrical body is erected and fixed, and the cross-sectional area (S) of the upper part of the roasting chamber １ ) is the area of ​​the bottom surface (S ２ A roasting device larger than ).

2. The roasting apparatus according to claim 1, wherein the inner wall surface of the roasting chamber is inclined such that the cross-sectional area increases along the height direction from the bottom surface.

3. The roasting apparatus according to claim 1, wherein the roasting chamber is configured as a combination of a tapered section whose inner diameter increases from the bottom upward in the height direction and a cylindrical section fixed at the maximum inner diameter of the tapered section.

4. The roasting apparatus according to claim 1, wherein the second heater is attached to the peripheral wall of the cylindrical body.

5. The roasting apparatus according to claim 4, wherein the second heater is a stick-type heater housed in the periphery wall of the roasting chamber along the height direction of the roasting chamber.

6. The roasting apparatus according to claim 1, wherein the upper end of the roasting chamber is provided with a powder separation means for separating the coffee bean dust generated by roasting.

7. The roasting apparatus according to claim 1, wherein the second heater is a band heater installed so as to cover the outer surface of the cylindrical body.

8. The roasting apparatus according to claim 1, wherein the normal airflow of the blower can be controlled to decrease from the initial stage of roasting to the later stage of roasting.

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