Drum roaster for roasting beans

Abstract

The invention relates to a drum roaster (2) for roasting beans, comprising a housing assembly (4) in which a roasting drum (12) for receiving the beans is rotatably mounted. A drive device for rotating the roasting drum (12) and a heating assembly (20) for heating the beans at least using hot air are provided, wherein the heating assembly (20) has at least one electric heating element (14), which is arranged in a heating tube (13) upstream of the roasting drum (12) when viewed in the flow direction of the hot air, for heating supply air and a vacuum fan (18), which is arranged downstream of the roasting drum (12) when viewed in the flow direction of the hot air, for suctioning the hot air out of the roasting drum (12). The heating assembly (20) has a supply air fan (16) which is arranged upstream of the electric heating element (14) when viewed in the flow direction of the supply air.

Description

[0001] DESCRIPTION

[0002] Drum roaster for roasting beans

[0003] The invention relates to a drum roaster for roasting beans, comprising a housing arrangement in which a roasting drum for receiving the beans is rotatably mounted, wherein a drive device for rotating the roasting drum and a heating arrangement for heating the beans at least by means of heating air are provided, wherein the heating arrangement has at least one electric heating element arranged in front of the roasting drum in a heating tube, as seen in the flow direction of the heating air, for heating supply air and a vacuum fan arranged behind the roasting drum, as seen in the flow direction of the heating air, for sucking the heating air out of the roasting drum.

[0004] Such drum roasters are well known in the art and are used primarily as so-called small, shop, or store roasters in smaller roasteries, shops, or cafes. An example of this is the drum roaster described in German utility model DE 20 2017 002 951 Ul. This uses an electric heating element, such as an electric hot air generator with ceramic heating elements, whose hot air is drawn into the roasting drum by a vacuum fan. With an electric heating element with a vacuum fan, the hot air generation is highly dependent on the ambient conditions. This can cause the vacuum conditions in the roasting drum to fluctuate considerably, which can lead to undesirable roasting results.It should be noted that in the field of household roasters (see, for example, EP 2 179 665 A1, roasting quantity 0.5 kg - 2 kg), it is known to arrange a fan in front of an electric heating element to feed heated air into a roasting drum. However, in this case, the heated air is even more difficult to control than in the above-mentioned embodiment with a vacuum fan.

[0005] The object of the invention is therefore to avoid the above-mentioned disadvantage in a simple and cost-effective manner.

[0006] This object is achieved according to the invention in that the heating arrangement comprises an air supply fan, which is arranged upstream of the electric heating element in the direction of air flow. This ensures a uniform air flow into the roasting drum in a particularly simple and cost-effective manner. The roasting process is very easy for the user to control. Furthermore, reliable cooling of the electric heating element is ensured in all operating situations. The air supply fan is advantageously designed as a side-channel fan.

[0007] A particularly simple and cost-effective electric heating element, which is also easy to cool, is designed as a ceramic heating element. In this case, channels are provided in a ceramic element in which heating rods are arranged. The supply air flows through these channels.

[0008] A preferred embodiment provides a control device, at least for the heating arrangement, which controls at least the heating process. A particularly advantageous embodiment is characterized by the provision of a collecting tank on the electric heating element for the supply air conveyed by the supply air fan. This collecting tank essentially serves to calm the supply air flow. By providing a pressure switch that is fluidically connected to the heating pipe, a minimum flow through the electric heating element can be ensured.

[0009] Particularly advantageously, a frequency converter is provided to control the supply air fan. This enables energy-efficient operation and simple speed control with a constant air flow of the supply air fan.

[0010] The inclusion of a temperature sensor in the heating tube allows for easy temperature monitoring of the electric heating element. If the temperature of the electric heating element becomes too high, the temperature sensor detects a safety shutdown of the electric heating element.

[0011] In a particularly advantageous embodiment, a safety temperature limiter is provided in the heating tube, which switches off the heating element in the event of overheating and can generate an error message.

[0012] In a particularly advantageous embodiment, the electric heating element has a clocked voltage supply as the first control circuit. This allows for simple regulation of the heating energy and, consequently, simple control of the roasting process. A semiconductor contactor with a PWM signal at the input can be provided for the clocked voltage supply, which signal can be determined by a PID controller, wherein a comparison of a heating air target temperature to the actual heating air temperature is made at the input of the PID controller.

[0013] electric heating element.

[0014] For a recipe temperature setting in an automatic roasting process, a second control loop can be provided, in which a comparison of a recipe target temperature with the recipe actual temperature takes place at the input of a PID controller. The roasting, heating air, and / or exhaust air temperatures can advantageously be considered as the recipe temperature.

[0015] The invention is explained in more detail with reference to a drawing, in which: Figure 1 shows a partially sectioned side view of a drum roaster according to the invention,

[0016] Figure 2 shows a detailed view of an electric heating element and a supply air fan fluidically connected to it,

[0017] Figure 3 is a schematic view of a first control loop, and Figure 4 is a schematic view of a second control loop.

[0018] Figure 1 shows a typical drum roaster 2 as a shop roaster. The drum roaster 2 has a housing assembly 4, which essentially comprises a drum housing part 6 and a base housing part 8. For the sake of clarity, the base housing part 8 is shown open, i.e. without any cladding panels. The drum housing part 6 is placed on the base housing part 8, wherein the base housing part 8 has a collecting container 10 for roasted beans. In and on the drum housing part 6, in a known manner, there is a roasting drum 12, which is shown here partially in section, as well as a drive device (not shown) for rotating the roasting drum 12 and an electric heating element 14 arranged in a heating tube 13, which is shown here only schematically, partially in section, for heating the hot air to be fed into or to the roasting drum 12, which is designed as a heating ceramic element.The heating tube 13 with the electric heating element 14, together with an air supply fan 16 and a vacuum fan 18, forms a heating arrangement 20, which ensures the supply of supply air as heated air into the roasting drum 12 and the removal as exhaust air through a known cyclone 22 and is controlled by a control device 23. Heat is transferred to the beans through direct contact with the heated air by convection and via the roasting drum 12 by conduction. A display 24 arranged on the drum housing part 6 serves as an input and display panel for the user.

[0019] Furthermore, the view shows a bean inlet hopper 26, a sampler assembly 28, and a bean outlet assembly 30, which also includes the collecting container 10. Below the collecting container 10, there is a mixing drive device 32 for a mixing device (not shown) rotatably mounted in the collecting container 10, and a cooling air blower 34 for supplying cooling air to the collecting container 10.

[0020] As already mentioned above, an air supply fan 16 is provided for supplying the supply air, which is arranged upstream of the electric heating element 14 in the direction of supply air flow. Between the air supply fan 16 and the heating pipe 13 with the electric heating element 14, a collecting tank 36 is also provided on the heating pipe 13, which calms the supply air flow. A pressure switch 38 is fluidically connected to the heating pipe 13 and monitors the pressure in the heating pipe 13, thereby ensuring a minimum flow and thus reliable cooling of the electric heating element 14. A frequency converter (not shown) for controlling the air supply fan 16 enables energy-efficient operation and simple speed control. A temperature sensor 40 is provided here to monitor the hot air temperature in the heating pipe 13; this sensor extends into the heating pipe 13 and monitors the temperature.In addition, a safety limiter 42 is provided on the heating tube 13, which immediately shuts off the electric heating element 14 if a limit temperature is exceeded. The pressure switch 38, the temperature sensor 40, and the safety limiter 42 are connected to the control device 23 in addition to the heating arrangement 20. To ensure simple regulation of the heating energy by the electric heating element 14, a pulsed voltage supply is provided, which forms a first control circuit 44 (see Figure 3). A second control circuit 46 is provided for setting a recipe temperature during automatic roasting and is described in connection with Figure 4.

[0021] Figure 2 now shows the heating pipe 13 with the upstream collecting tank 36 and the supply air fan 16 in detail. The pressure switch 38, the temperature sensor 40 and the safety limiter 42 are also clearly visible here.

[0022] Figure 3 shows a schematic view of the first control circuit 44 for the clocked voltage supply to the electric heating element 14, which is stored in the control device 23. A roasting process stored in the control device 23 specifies a percentage of the maximum heating output, which is converted in a block 48 into a recipe target temperature 50 in °C and compared with an actual recipe temperature 52. A difference value 53 serves as the input signal of a PID controller 54 of the electric heating element 14 and is fed as a PWM signal to a semiconductor contactor 56. This then generates the clocked voltage supply to the heating element 14, whose actual temperature, here the actual recipe temperature 52, is monitored by the temperature sensor 40.

[0023] Figure 4 shows a schematic view of the second control loop 46 for a recipe temperature setting during automatic roasting. A roasting process stored in the control device 23 selects a recipe target temperature 60 from a recipe in a block 58, which is compared with a recipe actual temperature 62. A difference value 64 serves as the input signal of a PID controller 66, which controls the heating arrangement 20. The recipe actual temperature 62 is also determined here by the

[0024] Temperature sensor 40 monitors the temperature. The roasting, heating air, and / or exhaust air temperatures can serve as the recipe target or actual temperature.

Claims

PROBAT AG PATENT CLAIMS 1. Drum roaster (2) for roasting beans, comprising a housing arrangement (4) in which a roasting drum (12) for receiving the beans is rotatably mounted, wherein a drive device for rotating the roasting drum (12) and a heating arrangement (20) for heating the beans at least by means of heated air are provided, wherein the heating arrangement (20) has at least one electric heating element (14) arranged in a heating tube (13) upstream of the roasting drum (12) as seen in the direction of flow of the heated air for heating supply air and a vacuum blower (18) arranged downstream of the roasting drum (12) as seen in the direction of flow of the heated air for sucking the heated air out of the roasting drum (12), characterized in that the heating arrangement (20) has a supply air blower (16) which is arranged upstream of the electric heating element (14) as seen in the direction of flow of the supplied air.

2. Drum roaster (2) according to claim 1, characterized in that a control device (23) is provided at least for the heating arrangement (20).

3. Drum roaster (2) according to claim 1 or 2, characterized in that the electric heating element (14) is designed as a heating ceramic element.

4. Drum roaster (2) according to one of claims 1 - 3, characterized in that on the electric heating element (14) a A collecting container (36) is provided for the supply air conveyed by the supply air blower (16). Drum roaster (2) according to one of claims 2-4, characterized in that a pressure switch (38) is provided which is fluidically connected to the heating tube (13). Drum roaster (2) according to one of the preceding claims, characterized in that a frequency converter is provided for controlling the supply air blower (16). Drum roaster (2) according to one of claims 2-6, characterized in that a temperature sensor (40) is provided in the heating tube (13). Drum roaster (2) according to one of claims 2-7, characterized in that a safety temperature limiter (42) is provided in the heating tube (13). Drum roaster (2) according to one of claims 2-8, characterized in that the electric heating element (14) has a clocked voltage supply as a first control circuit (44).Drum roaster (2) according to claim 9, characterized in that a semiconductor contactor with a PWM signal at the input is provided for the clocked voltage supply, which signal can be determined by a PID controller, wherein a comparison of a heating air target temperature to the heating air actual temperature in the electric heating element takes place at the input of the PID controller. Drum roaster (2) according to claim 7 or 8, characterized in that a second control circuit (46) is provided for setting a recipe temperature during automatic roasting, in which a comparison of a recipe target temperature with the recipe actual temperature takes place at the input of a PID controller. Drum roaster (2) according to claim 9, characterized in that the roasting, heating air, and / or exhaust air temperature is to be considered as the recipe temperature.

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