Roasting Equipment

Abstract

The present invention relates to an apparatus (10) for roasting coffee beans, comprising a roasting chamber (1) having a bottom opening (11), an air driver (2) configured to drive an air flow into the roasting chamber through the bottom opening of the chamber, an electric heater (3) arranged below the bottom opening of the chamber and configured to heat the air flow to be driven into the bottom opening of the roasting chamber, and a conduit (6) for driving the hot air flow from the heater (3) to the bottom opening of the roasting chamber (11), the conduit (6) including a localized transverse constriction (61), and at least one temperature probe arranged in the localized transverse constriction (61) of the conduit.

Description

[Technical field]

[0001] The present invention relates to an apparatus for roasting coffee beans with heated air, which is particularly suitable for use at home or in shops and cafes. [Background technology]

[0002] Small scale roasting of coffee beans in homes or shops and cafes is usually carried out using small devices in which the coffee beans are agitated in hot air. One type of device uses a rotating perforated drum into which the coffee beans are placed and tumbled while heat is applied.

[0003] Another type of device uses fluidized bed technology, implementing a hot air fluidized bed chamber. In such a chamber, heated air is forced through a screen or perforated plate beneath the coffee beans with enough force to lift the beans. Heat is transferred to the beans as they tumble and flow through this fluidized bed.

[0004] This technology, derived from industrial roasters described in U.S. Pat. No. 3,964,175, has been adapted for small domestic devices such as those described in U.S. Pat. Nos. 4,484,064, 4,494,314, 4,631,838, 5,269,072, and 5,564,331.

[0005] Roasters can use different types of heaters, such as gas burners or electric heaters. For small roasters, electric heaters, such as heating resistances, are usually preferred.

[0006] Most roasters implementing fluidized bed technology have the same configuration of main elements: roasting chamber, heater, and air driver. Very generally and obviously, these elements are stacked along a vertical axis, with the air driver located at the lowest position, above it the electrical resistor, and above the electrical resistor the roasting chamber.

[0007] Roasting is performed by applying a specific heat vs. time curve to the coffee beans (called the roast profile). The control of this roast profile is performed via control of the heater power and / or the air driver power, and usually this control is obtained by monitoring the temperature with a temperature sensor (process control by feedback loop). Ideally, this sensor is placed inside the roasting chamber to measure the temperature of the beans themselves. Furthermore, preferably in small roasters, the hot air fluidized bed chamber is removable from the device for manual introduction and removal of the beans as well as for cleaning operations. In such removable chambers, it is not recommended to place a temperature probe inside the chamber, and usually in that configuration it is preferred to place the temperature sensor below the removable chamber, for example inside the duct that leads the hot air to the chamber. However, it has been observed that in this configuration the measurements are not very accurate, with the effect that the lack of accurate information in the temperature feedback loop results in a less than optimal roast.

[0008] The object of the present invention is to solve that problem. Summary of the Invention

[0009] According to a first aspect of the present invention, there is provided an apparatus for roasting coffee beans, the apparatus comprising: a roasting chamber having a bottom opening; an air driver configured to drive an air flow into the roasting chamber through a bottom opening of the chamber; an electric heater arranged below the bottom opening of the roasting chamber and configured to heat the airflow that is propelled into the bottom opening of the chamber; the apparatus includes a conduit for propelling hot air from the heater to a bottom opening of the roasting chamber; the conduit includes a localized transverse constriction that reduces a cross-section of the conduit to a minimum cross-sectional area; At least one temperature probe is positioned at the smallest cross-section of the local transverse constriction of the conduit.

[0010] The roasting apparatus comprises a roasting chamber having a bottom opening and usually a top opening, the roasting chamber being designed such that a fluidized bed of hot air can be created when hot air is introduced through the bottom opening.

[0011] Typically, the bottom opening includes a grid to retain the beans within the chamber while allowing hot air to pass through the chamber.

[0012] The top opening allows the evacuation of smoke and particles produced during the roasting operation, and also allows the loading of the beans to be roasted and the removal of the roasted beans at the end of the roasting operation, for this last operation the roasting chamber being removable from the housing of the device.

[0013] The apparatus includes an air driver configured to propel an air flow inside the roasting chamber through a bottom opening of the chamber, typically an air blower or fan designed to blow air upwards into the roasting chamber.

[0014] The apparatus includes an electric heater disposed below a bottom opening of the chamber and configured to heat the flowing air before it is introduced inside the roasting chamber.

[0015] Typically, the heater is located directly below the bottom opening of the chamber to limit heat loss during the hot air transfer from the heater to the roasting chamber. This location of the heater also provides good temperature regulation during the roasting process in the roasting chamber. Indeed, any temperature change of the heater directly affects the temperature inside the roasting chamber.

[0016] Additionally, the apparatus comprises a conduit, pipe, channel or tube for driving the hot air flow from the heater to the bottom opening of the roasting chamber, the conduit thus guiding the hot air flow from the heater to the bottom opening of the chamber.

[0017] The conduit includes a localized transverse constriction that reduces a cross-section of the conduit to a minimum cross-sectional area, and at least one temperature probe is disposed at the localized transverse constriction of the conduit at the minimum cross-sectional area of ​​the conduit.

[0018] This local transverse constriction reduces the hydraulic diameter of the conduit along a short length of the conduit, the airflow passing through this reduction is more homogenized than upstream, and as a result, the temperature measured at this location is more accurate and reliable.

[0019] Generally, the apparatus comprises a controller configured to control the apparatus, the controller adapted to control the electric heater and / or the air driver based on a temperature of the air flow measured by at least one temperature probe.

[0020] The hot air flow introduced into the roasting chamber can be more accurately and reliably measured, improving the control of the electric heater and / or air driver via a feedback loop to perfectly apply the predefined roast profile curve to the beans, thus providing a repeatable and consistent roast.

[0021] At least two temperature probes can be arranged in the plane of the smallest cross section, each probe being arranged at a different radial position. The presence of several probes measuring temperature at different points in the plane of the smallest cross section allows for verification of the homogeneity of the hot air flow.

[0022] In a preferred embodiment, the minimum cross-sectional hydraulic diameter may be between 15 and 25 mm.

[0023] Within such ranges the risk of different air flows at different temperatures is minimized.

[0024] By hydraulic diameter is meant the diameter of a conduit having a circular cross section which is the same cross sectional area as a conduit having a cross section of a different shape.

[0025] Preferably, the design of the constriction comprises a gradual reduction in the cross-section of the conduit to a minimum cross-section and a gradual expansion in the cross-section of the conduit from said minimum cross-section.

[0026] The constriction therefore includes progressively converging and progressively diverging regions. In addition to the effect of homogenizing the air flow at the smallest cross section, this design accelerates the speed of the hot air flow downstream of the constriction. As a result, the hot air can be introduced into the roasting chamber at high speed, with the accompanying effect that a fluidized bed of air is formed and the coffee beans can be stirred, even if they are dense, such as moist green beans. The beans are energetically impacted by the hot air flow at the bottom opening of the chamber and are thrown upwards, allowing other beans to be placed at the bottom. As a result, the beans are instead placed at the bottom of the chamber, which ensures a homogenized roasting of all the beans and avoids overheating of some beans.

[0027] Preferably, the minimum cross-sectional hydraulic diameter

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[0028] Generally, the conduit has the same hydraulic diameter and the same shape upstream and downstream of the smallest cross-sectional area.

[0029] Preferably, the bottom of the roasting chamber is located above the smallest cross-section by a distance d, the distance d being between 2 and 3 times the hydraulic diameter of the smallest cross-section.

[0030] Since the bottom of the roasting chamber supports the coffee beans introduced inside the chamber, this distance allows the creation of an increased velocity hot air flow at the bottom opening of the chamber to agitate the beans.

[0031] In one embodiment, the conduit may include a static mixer, the static mixer being located upstream of the constriction.

[0032] The static mixer is configured to disrupt the hot air flow and mix various potential zones of air exhibiting different temperatures downstream of the heater. A constriction can then homogenize the temperature and pressure of the mixed flow before delivering homogenized hot air to the roasting chamber.

[0033] The static mixer may be designed to create turbulence, rotation or swirl of the hot air.

[0034] Any type of air static mixer can be used. The static mixer can be designed in the side wall of the conduit, for example as a hollow groove in the side wall, and can take the form of a spiral or screw thread. The static mixer can include fins extending from the side wall of the conduit through the cross section of the conduit.

[0035] As mentioned above, preferably the roasting chamber is removably mounted to the housing, and a bottom opening of the roasting chamber cooperates with the hot air outlet end of the conduit when the roasting chamber is mounted to the housing of the apparatus.

[0036] The above aspects of the invention may be combined in any suitable combination. Moreover, various features herein may be combined with one or more of the above aspects to provide combinations other than those specifically shown and described. Further objects and advantageous features of the invention will become apparent from the claims, detailed description, and accompanying drawings. [Brief description of the drawings]

[0037] Preferred embodiments of the invention will now be further described, by way of example only, with reference to the accompanying schematic drawings, in which: [Figure 1] FIG. 1 is a schematic diagram of a roasting device according to the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a hot air flow generating unit of the apparatus of FIG. 1. [Diagram 3] 1 shows a schematic vertical and cross-sectional view of the conduit and the bottom of the roasting chamber in a device according to the invention; [Figure 4] FIG. 2 is a block diagram of a control system of the device according to FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Roasting Equipment 1 shows an exemplary side view of a roasting apparatus 10. Functionally, the roasting apparatus 10 is operable to roast coffee beans held in a chamber 1 by a hot air current introduced inside the chamber 1. On a first level, the apparatus comprises a housing 4, a roasting unit, and a control system 80. These components will now be described in turn.

[0039] Roasting unit of roasting equipment The roasting unit is operable to receive and roast coffee beans.

[0040] The roasting unit typically comprises, on the second level of the roasting apparatus 10, a chamber 1, an airflow driver 2 and a heater 3, which will be described in turn.

[0041] The chamber 1 is configured to receive and hold coffee beans introduced by an operator. In a preferred embodiment, the chamber 1 is removable from the housing 4. The chamber comprises: For the introduction or removal of coffee beans, or Once the chamber is removed, it can be cleaned and maintained, or To clean the vertical housing part 43 behind the chamber, It can be placed next to the roasting device.

[0042] The bottom opening 11 of the chamber is configured to allow air to pass through and may in particular comprise a perforated plate onto which the beans can be placed and through which air can flow upwards. The chamber 1 comprises a handle to enable the user to remove the chamber from the housing and to hold it outside the housing.

[0043] A chaff collector (not shown) is in flow communication with chamber 1 for receiving husks (chaff) which progressively separate from the beans and which, due to their low density, are blown into the chaff collector.

[0044] The air driver 2 is operable to generate an air flow (dotted arrow) in the direction of the bottom of the chamber. The generated flow is configured to heat, stir and lift the beans, resulting in homogeneous heating of the beans. In particular, the air flow driver may be a fan driven by a motor. An air inlet 42 may be provided at the base of the housing to supply air inside the housing, and the air flow driver may blow this air upwards through the passage 5 to the air outlet holes 41 in the direction of the chamber 1, as indicated by the dotted arrow.

[0045] The heater 3 is operable to heat the airflow generated by the airflow driver 2. In the particular embodiment shown, the heater is located between the fan 2 and the bottom opening 11 of the chamber, so that the airflow is heated before it enters the chamber 1, lifting the beans. The heater 3 is usually located directly below the air outlet holes 41, typically by a maximum of 10 cm, to better control the heating and avoid heat loss.

[0046] The heater 3 is operable to apply a roast profile to the beans, the roast profile being defined as a curve of temperature against time.

[0047] When the chamber is mounted in the housing, the bottom of the chamber is tightly connected to the air outlet hole 41, preventing the hot air flow from leaking at the connection.

[0048] The top opening 12 of the chamber is connected to a smoke and particle exhaust system (not shown).

[0049] Figure 2 shows more precisely the hot air flow generating unit of Figure 1, in particular the conduit or pipe 6 which drives the hot air flow from the heater to the bottom opening 11 of the roasting chamber. This conduit 6 includes a local transverse constriction 61, in which one temperature probe 7 is placed.

[0050] Passing through this constriction, the hot air stream is homogenized and the temperature measured by the probe 7 provides exactly the temperature of the hot air further supplied to the bottom 11 of the roasting chamber. It is shown diagrammatically how large the part of the passage 5 where the air stream contacts the heater 3 may be, this part may contain several air streams, each heated by different parts of the heater and more or less close to the side of the passage 5. These streams are treated differently and although they may have the same range of temperatures, temperature probes placed at different radial positions of the cross section of the passage 5 will measure different temperatures. If the information monitored to control the heater and / or air driver in a feedback loop to apply a particular roast profile (temperature vs. time curve) is temperature, this temperature difference is not acceptable and leads to inconsistent roasts.

[0051] As indicated by the arrows in the region of the constriction, the constriction forces the different non-homogeneous flows to mix, so that the air flow at all other cross sections of the constriction has the same temperature. As a result, the constriction homogenizes the air flow, and the air flow and temperature measured by probe 7 at the constriction accurately reflects the temperature of the hot air flow supplied to the bottom 11 of the chamber and can be reliably used in a feedback loop for heating control.

[0052] FIG. 3 provides more details regarding the constriction 61 of the conduit 6 by a vertical cross-section along the vertical plane BB and a cross-section along the horizontal plane AA which intersects the smallest cross-section of the conduit at the constriction 61 .

[0053] A conduit 6 directs the hot air flow F, which has just come into contact with the heater, to the bottom opening 11 of the roasting chamber. The roasting chamber 1 contains coffee beans 16. The beans are held inside the chamber by a grid or sieve, through which the hot air therefore passes freely.

[0054] The conduit 6 comprises a constriction 61, the upstream diameter D of the conduit decreasing to a relatively small diameter through a reduction 61a.

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[0055] Preferably, through this gradual reduction 61a, the hydraulic diameter D of the conduit upstream of the constriction 61 is reduced to a minimum cross-sectional hydraulic diameter

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[0056] As shown in the cross-sectional view, at least one probe (here two) is positioned in the constriction to measure the temperature of the air passing through the constriction. Because the cross-section is small, the measured temperature is uniform regardless of the radial position within the cross-section of the probe. Preferably, the smallest cross-sectional hydraulic diameter of the constriction is 10 mm.

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[0057] The conduit 6 can be manufactured with this particular internal design of the constriction, or alternatively, an insert can be placed and attached inside a straight conduit.

[0058] The constriction is limited to a localized area. Downstream of the smallest cross-section the conduit typically presents the same cross-section as upstream of the smallest cross-section. Preferably, the constriction includes a gradual opening 61b. The longitudinal length of the gradual reduction 61a may be approximately 15mm, and similarly the gradual opening 61b may be approximately 15mm.

[0059] In addition to the gradual opening 61b downstream of the constriction, the velocity of the air flow F downstream of the constriction increases. This increased air velocity is particularly useful when the air flow impacts the coffee beans 16 in the roasting chamber, since it exerts a sufficient force on the beans to lift them, even if they are dense, such as green beans. The beans are separated from each other and the beans located at the lowest position of the chamber are replaced, limiting the risk of tipping them over. This effect is enhanced if the constriction 61 is not far from the bottom 11 of the chamber. Preferably, the bottom 11 of the roasting chamber is located above the minimum cross-section by a distance d, which distance d is equal to the hydraulic diameter of the minimum cross-section.

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[0060] In addition, even if some turbulence occurs in the air flow downstream of the constriction, the short distance between the constriction 61 and the bottom 11 does not result in a change in the temperature measured by the probe(s) and the feedback loop is reliable.

[0061] Roasting Equipment Control System 1 and 4, a control system 80 is discussed, wherein the control system 80 is operable to control the components of the apparatus for roasting coffee beans. The control system 80 typically comprises at a second level of the roasting apparatus: a user interface 17, a processing unit 8, a temperature probe 7, a power supply 14, a memory unit 9, sensors 18, optionally a communication interface 13 for remote connection, optionally a code reader 15.

[0062] The user interface 17 includes hardware that allows a user to interface with the processing unit 8 by way of user interface signals. More specifically, the user interface receives commands from a user, which the processing unit 8 forwards as inputs to. The commands may be, for example, instructions to carry out a roasting process and / or to adjust operating parameters of the roasting apparatus 10 and / or to power the roasting apparatus 10 on or off. The processing unit 8 may also output feedback to the user interface 17 as part of the roasting process, for example to indicate that a roasting process has been started, or that parameters associated with the process have been selected or evolved during the process, or to generate an alarm.

[0063] In certain embodiments, the user interface may be used to provide an identification of the coffee beans introduced inside the chamber by a user, either by manual input, such as selecting an identification type in a pre-selected coffee bean list, or by inputting a digital reference of the coffee, for example read from a coffee bean package.

[0064] The user interface hardware may include any suitable device(s), for example the hardware includes one or more of the following: a joystick button, a button such as a knob or push button, a joystick, an LED, a graphic or text LCD, a graphic screen with touch sensitive buttons and / or screen edge buttons. The user interface 20 may be formed as one unit or as multiple separate units.

[0065] Part of the user interface may also be on a mobile app if the apparatus is provided with a communications interface 13, as described below, through which inputs and outputs can then be transmitted to the mobile device.

[0066] The sensors 18 are operable to provide input signals to the processing unit 8 to monitor the roasting process and / or the condition of the roasting apparatus. The input signals can be analog or digital signals. The sensors 18 typically include one or more of a bean level sensor associated with the chamber 1, an air flow sensor, a position sensor associated with the chamber and / or a chaff collector.

[0067] Similarly, the temperature probe 7 provides an input signal to the processing unit 8 for monitoring the roasting process at the local transverse constriction 61.

[0068] A code reader 15 may be provided which may be operable to read a code on the coffee bean packaging and automatically provide an input which is an identifier of the coffee beans introduced into the chamber 1 .

[0069] The processing unit 8 typically comprises memory and input / output system components that are usually configured as an integrated circuit such as a microprocessor or microcontroller. The processing unit 8 may comprise other suitable integrated circuits such as, for example, ASICs, programmable logic devices such as PALs, CPLDs, FPGAs, PSoCs, analog integrated circuits such as systems on chips (SoCs), controllers, etc. For such devices, where appropriate, the above program code may be considered as or may additionally include programmed logic. The processing unit 8 may also comprise one or more of the above integrated circuits. The latter example is one in which several integrated circuits are arranged to communicate with each other in a modular manner, e.g. a slave integrated circuit for controlling the user interface 17 communicates with a master integrated circuit for controlling the roasting unit 10.

[0070] The power supply 14 is operable to provide electrical energy to the above-mentioned controlled components and the processing unit 8. The power supply 14 may include various means such as a battery or a unit for receiving and regulating mains power. The power supply 14 may be operatively connected to a part of the user interface 17 for powering the roasting apparatus 10 on and off.

[0071] The processing unit 8 typically comprises a memory unit 9 for storing instructions as program code and optionally data. To this end, the memory unit typically comprises a non-volatile memory, e.g. EPROM, EEPROM or Flash, for storing program code as instructions and operating parameters, and a volatile memory (RAM) for storing temporary data. The memory unit may comprise a separate and / or integrated memory (e.g. on a semiconductor die). For programmable logic devices, the instructions may be stored as programmed logic.

[0072] The instructions stored in the memory unit 9 may ideally be thought of as comprising a coffee bean roasting program.

[0073] The coffee bean roasting program may use the signal of the temperature sensor 7 to control the air flow driver 2 and / or the heater 3.

[0074] The processing unit 8 is Receives input from temperature sensor 7; processing the inputs in accordance with roasting program code (or programmed logic) stored in the memory unit 9 (or eventually input from an external source such as the communications interface 13); It is operable to provide an output that is a roasting process according to a roast recipe. More specifically, the output includes the operation of at least the heater 3 and the airflow driver 2.

[0075] The temperature measured by the temperature probe 7 is used in a feedback loop to adapt the power of the heater 3 and / or the power of the air driver 2 in order to apply a predetermined roast profile to the beans.

[0076] Depending on the type of control applied to the roaster, the heater 3 may be supplied with one predetermined power, meaning that the heater temperature is constant, and the power of the air driver 2 may then be controlled based on the temperature monitored by the probe 7 to vary the contact time of the air flow through the heater during its travel.

[0077] Alternatively, the air driver 2 can be supplied with one predetermined power, meaning that the flow rate is constant, and the power of the heater 2 can then be controlled based on the temperature monitored by the probe 7 to heat more or less air as it passes through the heater.

[0078] In a final alternative, both the heater 3 and the air driver 2 can be controlled based on the monitoring of temperature by the probe 7 .

[0079] While the invention has been described with reference to the above illustrated embodiments, it will be understood that the invention as claimed is in no way limited to these illustrated embodiments.

[0080] Variations and modifications can be made without departing from the scope of the invention as defined in the claims. Furthermore, where known equivalents exist to specific features, such equivalents are incorporated as if specifically referred to herein.

[0081] As used herein, the terms "comprises," "comprising," and similar terms should not be construed in an exclusive or exhaustive sense. In other words, they are intended to mean "including, but not limited to." [Explanation of symbols]

[0082] 1 Roasting chamber 11 Bottom opening 12 Top opening 2 Air Driver 3 Heater 4. Housing 41 Air outlet hole 42 Air inlet 43 Vertical section 5 Air passage 6 Duct 61 Stenosis 61a Reduced section 61b opening 7 Temperature Probes 8. Control System 80 Processing Units 10 Roasting Equipment 13 Communication Interface 14 Power supply 15 Code Reader 16 Coffee Beans 17 User Interface 18 Sensors

Claims

1. An apparatus (10) for roasting coffee beans, comprising: A roasting chamber (1) having a bottom opening (11); an air driver (2) configured to drive an air flow inside the roasting chamber through the bottom opening of the chamber; an electric heater (3) arranged below the bottom opening of the chamber and configured to heat the airflow that is propelled into the bottom opening of the roasting chamber; The device comprises a conduit (6) for driving a hot air current from the heater (3) to the bottom opening (11) of the roasting chamber, the conduit (6) comprises a local transverse constriction (61) which reduces the cross section of the conduit to a minimum cross section; At least two temperature probes (7) are positioned at the smallest cross-section of the conduit to measure the temperature of the air flow passing through the local transverse constriction, each probe being positioned at a different radial position.

2. 2. The apparatus according to claim 1, comprising a controller (8) configured to control the apparatus, the controller being adapted to control the electric heater (3) and / or the air driver (2) based on the temperature of the air flow measured by the at least two temperature probes (7).

3. the hydraulic diameter of the smallest cross-sectional area of ​​the localized transverse constriction [0010] The device according to claim 1 or 2, wherein the distance is between 15 and 25 mm.

4. 4. The device according to claim 1, wherein the design of the constriction comprises a gradual narrowing (61a) of the cross-section of the conduit to the smallest cross-section and a gradual opening (61b) of the cross-section of the conduit from the smallest cross-section.

5. said minimum cross-sectional hydraulic diameter [0025] is between 1 / 3 and 2 / 3 of the hydraulic diameter (D) of the conduit upstream of the constriction.

6. The bottom opening (11) of the roasting chamber is located above the minimum cross-section by a distance d, said distance d being equal to the hydraulic diameter of the minimum cross-section. [0030] The device according to any one of claims 1 to 5, wherein the ion exchange rate is 2 to 3 times higher than the ion exchange rate.

7. The device according to any one of the preceding claims, wherein the conduit (6) is provided with a static mixer, the static mixer being arranged upstream of the constriction.

8. 8. Apparatus according to any one of claims 1 to 7, wherein the roasting chamber is removably mounted in a housing (4), and the bottom opening (11) of the roasting chamber cooperates with a hot air outlet end of the conduit when the roasting chamber is mounted in the housing (4) of the roasting apparatus.

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