Drum-type roasting machine for coffee beans

Abstract

The present invention relates to a drum-type roaster (2) for roasting beans, comprising a housing assembly (4) for rotatably supporting a roasting drum (12) containing beans. The roasting drum (12) is also provided with a drive means for rotating the roasting drum (12) and a heating assembly (20) for heating the beans with at least heated air. The heating assembly (20) has at least one electric heating element (14) for heating supply air, which is disposed in a heating pipe (13) upstream of the roasting drum (12) in the direction of heated air flow. A suction fan (18) for exhausting the heated air from the roasting drum (12) is disposed downstream of the roasting drum (12) in the direction of heated air flow. The heating assembly (20) also has a blower fan (16) disposed upstream of the electric heating element (14) in the direction of supply air flow.

Description

Technical Field

[0001] The present invention relates to a drum-type roasting machine for roasting beans, and includes a housing assembly that rotatably supports a roasting drum for containing beans. Further, drive means for rotating the roasting drum and a heating assembly for heating the beans by at least hot air are provided. The heating assembly has at least one electric heating element for heating the supply air. The electric heating element is disposed in a heating pipe upstream of the roasting drum in the direction in which the hot air flows. A suction fan for exhausting the hot air from the roasting drum is disposed downstream of the roasting drum in the direction in which the hot air flows.

Background Art

[0002] Such drum-type roasting machines are well-known in the art and are used particularly as so-called small-scale roasting machines or store roasting machines in small-scale roasting factories, stores, and cafes. As an example of this, there is a drum-type roasting machine described in the German Utility Model No. 202017002951. An electric heating element such as an electric heating air generator having a ceramic heating resistor is provided, and the hot air is sucked into the roasting drum by a suction fan. The generation of hot air by the electric heating element having this suction fan greatly depends on the surrounding conditions. This means that the reduced pressure state in the roasting drum may fluctuate significantly, leading to undesirable roasting results. In the field of home roasting machines (for example, see European Patent No. 2179665, roasting amount 0.5 kg to 2 kg), it is known to arrange a blower with a high discharge pressure on the upstream side of the electric heating element to allow the hot air to flow into the roasting drum. However, this makes the control of the hot air even more difficult than in the above-described embodiment having a suction fan.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An object of the present invention is to avoid the above-mentioned drawbacks in a simple and cost-effective manner.

Means for Solving the Problems

[0004] This objective is achieved by a heating assembly equipped with a blower fan according to the present invention. The blower fan is positioned upstream of the electric heating element in the direction of airflow. This ensures a uniform flow of air supplied to the roasting drum in a particularly simple and cost-effective manner. The roasting process is controllable by the user in a very simple manner. In addition, reliable cooling of the electric heating element is ensured under all operating conditions. The blower fan is preferably configured as a side fan.

[0005] Ceramic heating elements are particularly easy and inexpensive to manufacture and are configured as electric heating elements that can be cooled by a simple method. In this configuration, a flow path is provided in the ceramic element, and a heating rod is placed within it. Supply air flows through the flow path.

[0006] In a preferred embodiment, the system includes at least a control device for the heating assembly, which controls at least the heating process.

[0007] In a preferred embodiment, a collection container for supply air, which is transported by a blower fan, is provided on the electric heating element. This collection container essentially plays a role in smoothing the flow of supply air. By providing a pressure monitor fluid-connected to the heating tube, it is possible to ensure a minimum flow rate passing through the electric heating element.

[0008] It is preferable to provide a frequency converter for controlling the blower fan. This enables energy-efficient operation of the blower fan with a constant airflow and simple speed control.

[0009] A temperature sensor inside the heating tube makes it easy to monitor the temperature of the electric heating element. If the temperature of the electric heating element becomes too high, the temperature sensor will detect this and shut off the electric heating element for safety reasons.

[0010] In a preferred embodiment, a protective temperature limiter is provided inside the heating tube, and if overheating occurs, the heating element can be turned off and an error message can be generated.

[0011] In a preferred embodiment, the electric heating element includes a clock-controlled power supply as a first control circuit. This allows for simple control of the heating energy and, consequently, the roasting process. For this purpose, a semiconductor switch with a PWM signal at its input can be installed in the clock-controlled power supply. This signal can be determined by a PID controller, and the input of the PID controller of the electric heating element compares the set heating air temperature with the actual heating air temperature.

[0012] A second control circuit can be installed during automatic roasting to set the temperature according to the recipe. This second control circuit compares the set recipe temperature with the actual recipe temperature at the input of the PID controller. Preferably, the roasting temperature, heated air temperature, and / or exhaust temperature can be considered as recipe temperatures.

[0013] The present invention will be further described with reference to the drawings. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a partial cross-sectional side view of the drum-type roasting machine according to the present invention. [Figure 2] Figure 2 is a detailed view of an electric heating element and a blower fan fluidly connected to that element. [Figure 3] Figure 3 is a schematic diagram of the first control circuit. [Figure 4] Figure 4 is a schematic diagram of the second control circuit. [Modes for carrying out the invention]

[0015] Figure 1 shows a typical drum-type roaster 2 as a commercial roaster. The drum-type roaster 2 basically has a housing assembly 4 comprising a drum housing section 6 and a base housing section 8. For clarity, the base housing section 8 is open and does not have a cover panel as shown. The drum housing section 6 is positioned on the base housing section 8, and the base housing section 8 includes a container 10 for roasting beans. Inside and on top of the drum housing section 6, a roasting drum 12 (shown here in a partial cross-sectional view), a drive mechanism for rotating the roasting drum 12 (not shown in detail), and a heating element 14 (shown here in a schematic partial cross-sectional view) for heating the heated air supplied to the roasting drum 12 are arranged in known manner. The heating element 14 is configured as a ceramic heating element. The heating tube 13, including the electric heating element 14, together with a blower fan 16 and a suction fan 18, constitutes a heating assembly 20. The heating assembly 20 supplies air to be blown into the roasting drum 12 as heated air, and ensures that exhaust is removed by a cyclone 22 of a known type. This assembly is controlled by a control device 23. Heat transfer to the beans occurs through direct contact by convection of heated air and through conduction via the roasting drum 12. The display 24 located in the drum housing 6 functions here as an input and display panel for the user.

[0016] Furthermore, a bean inlet funnel 26, a sample extraction device 28, and a bean outlet device 30 including a collection container 10 are shown in the figure. Below the collection container 10 are a mixing drive device 32 (not shown in detail) for a mixing device, which is rotatably supported within the collection container 10, and a cooling air fan 34 that supplies cooling air to the collection container 10.

[0017] As already mentioned, a blower fan 16 is provided to supply blown air, and this blower fan 16 is positioned upstream of the electric heating element 14 in the direction of airflow. Furthermore, the heating tube 13 is provided with a collection container 36 between the blower fan 16 and the heating tube 13 containing the electric heating element 14 to stabilize the flow of the blown air. A pressure monitor 38 is fluidly connected to the heating tube 13 and monitors the pressure inside the heating tube 13, thereby ensuring reliable cooling of the electric heating element 14 by maintaining a minimum flow rate. A frequency converter (not shown in detail) that controls the blower fan 16 enables energy-efficient operation and simple speed control.

[0018] A temperature sensor 40 is provided to monitor the temperature of the heated air inside the heating tube 13, and this temperature sensor 40 extends into the heating tube 13 to monitor the temperature. Furthermore, the heating tube 13 is provided with a protection limiter 42 that immediately stops the electric heating element 14 if the temperature limit is exceeded. The pressure monitor 38, temperature sensor 40, and protection limiter 42 are connected to the control device 23 via a heating assembly 20 using control technology. A clock control power supply is provided to easily control the heating energy of the electric heating element 14, and this constitutes the first control circuit 44 (see Figure 3). A second control circuit 46 is provided for recipe-based temperature control during automatic roasting and is illustrated in Figure 4.

[0019] Figure 2 shows the heating tube 13 with the upstream collection container 36 and blower fan 16 in detail. The pressure monitor 38, temperature sensor 40, and protective temperature limiter 42 are also clearly visible here.

[0020] Figure 3 shows a schematic diagram of the first control circuit 44 for the clock control power supply of the electric heating element 14, which is mounted on the control device 23. The roasting process stored in the control device 23 specifies the percentage of maximum heating power. This is converted to a set recipe temperature 50 in °C in block 48 and compared with the actual recipe temperature 52. The difference value 53 functions as the input signal to the PID controller 54 of the electric heating element 14 and is supplied to the semiconductor switch 56 as a PWM signal. Next, a clock power supply is generated for the heating element 14, whose actual temperature (in this case, the actual recipe temperature 52) is monitored by the temperature sensor 40.

[0021] Figure 4 shows a schematic diagram of the second control circuit 46 that sets the recipe temperature during the automatic roasting process. The roasting process stored in the control device 23 selects the recipe set temperature 60 from the recipe in block 58 and compares it with the actual recipe temperature 62. The difference value 64 serves as an input signal for the PID controller 66 that controls the heating assembly 20. The actual recipe temperature 62 is also monitored here by the temperature sensor 40. The roasting, heating air, and / or exhaust temperatures can function as the recipe set point or the actual temperature.

Claims

1. A drum-type roasting machine (2) for roasting beans, comprising a housing assembly (4) that rotatably supports a roasting drum (12) for containing beans, The roasting drum (12) is provided with a drive means for rotating it and a heating assembly (20) for heating the beans with at least heated air. The heating assembly (20) includes at least one electric heating element (14) for heating the supply air and a suction fan (18) for exhausting the heated air from the roasting drum (12), wherein the electric heating element (14) is located in a heating tube (13) upstream of the roasting drum (12) in the direction of the flow of the heated air, and the suction fan (18) is located downstream of the roasting drum (12) in the direction of the flow of the heated air. The heating assembly (20) has a blower fan (16) positioned upstream of the electric heating element (14) in the direction in which the supply air flows, in a drum-type roasting machine (2).

2. The drum-type roaster (2) according to claim 1, wherein at least a control device (23) for the heating assembly (20) is provided.

3. The drum-type roaster (2) according to claim 1, wherein the electric heating element (14) is configured as a ceramic heating element.

4. The drum-type roaster (2) according to claim 1, wherein a collection container (36) for the blown air supplied by the blower fan (16) is provided on the electric heating element (14).

5. The drum-type roaster (2) according to claim 2, wherein a pressure monitor (38) is provided that is fluidly connected to the heating tube (13).

6. The drum-type roaster (2) according to any one of claims 1 to 5, further comprising a frequency converter for controlling the blower fan (16).

7. A drum-type roaster (2) according to any one of claims 2 to 5, wherein a temperature sensor (40) is provided on the heating tube (13).

8. A protective temperature limiter (42) is provided on the heating tube (13) in the drum-type roaster (2) according to any one of claims 2 to 5.

9. The drum-type roaster (2) according to any one of claims 2 to 5, wherein the electric heating element (14) is equipped with a clock-controlled power supply as a first control circuit (44).

10. The drum-type roaster (2) according to claim 9, wherein a semiconductor switch having a PWM signal that can be determined by a PID controller is provided in the input section of the clock control power supply, and the set temperature of the heated air is compared with the actual temperature of the heated air in the electric heating element at the input section of the PID controller.

11. The drum-type roaster (2) according to claim 7 is provided with a second control circuit (46) for setting the temperature used during automatic roasting, and the set temperature is compared with the actual temperature at the input section of the PID controller.

12. The drum roaster (2) according to claim 9, wherein the roasting temperature, heated air temperature and / or exhaust temperature are considered as temperatures used during automatic roasting.

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