Dosing device for granular material with controlled central dosing unit

Description

[0001] The invention relates to a metering device for granular material, in particular for seed. The metering device comprises a storage container for the granular material, a central metering device connected to the storage container, a first pneumatic conveying channel connected to the central metering device for pneumatically conveying granular material to a distribution head, at least one sowing device, and a second pneumatic conveying channel for pneumatically conveying granular material from the distribution head to at least one sowing device.

[0002] Dosing devices of this type are well known. They are used, for example, in agricultural seed drills for conveying and dosing seed to be sown on an agricultural field.

[0003] The sowing device can essentially consist of a seed coulter, which deposits the supplied granular material into the soil. However, seeding devices with associated singling elements are also known. In these devices, the seed fed via the distribution head is first singulated and only then fed to the seed coulter for placement in the soil. Metering devices of the above-mentioned type for precision seed drills are known, for example, from EP 2 298 056 B1 and EP 2 591 656 A1.

[0004] To adjust the amount of granular material added via the central metering device, a calibration test is typically used. Especially for precision seed drills, solutions have also become known that incorporate grain counters at the outlet of the singulating elements and use the measured values ​​of these grain counters to regulate the central metering device. However, this requires the measured values ​​of the grain counters of all seeding devices to be taken into account and converted into a setting for the central metering device.

[0005] A similar sowing device is described in DE 10 2014 115 020 A1. Here, grain-counting sensor devices are provided in feed lines that connect the seed coulters to a central distribution head. The central metering device is adjusted based on the measured values. Another sowing device is known from EP 2 923 545 A1.

[0006] In known systems, setting up the central dosing unit is therefore relatively complex.

[0007] The object of the invention is therefore to provide a dosing device for granular material in which the adjustment of a central dosing device used can be carried out in a simple manner. This object is achieved by a dosing device according to claim 1. Further advantageous embodiments of the invention are specified in the dependent claims.

[0008] According to the invention, the sowing device has at least one air outlet opening that can be at least partially blocked by a buffer of granular material or by a blocking element. A sensor unit is provided with which the pressure (of the flowing air) prevailing in the first pneumatic conveying channel, the second pneumatic conveying channel, and / or the distribution head can be determined. Based on one or more measured values ​​from this sensor unit, the central dosing device can then be regulated or controlled.

[0009] The invention is based on the following principle. The at least one air outlet opening of the sowing device can be closed according to the buffer fill level, which leads to increased flow resistance of the conveying air flow. This, in turn, causes a pressure increase in the conveying air line. This pressure increase can be recorded by the sensor unit. The determined pressure can then be used to control the central dosing device.

[0010] Since the increased pressure also results in a reduced conveying air flow, according to an embodiment not according to the invention, the volume flow can also be determined via the sensor unit as an alternative or in addition to determining the pressure. The determined volume flow can then be used to control the central dosing device.

[0011] The granular material can be seed, but alternatively or additionally it can also be granular fertilizer or granular pesticide. Therefore, although this refers to a seeding device, it can also be suitable for applying granular fertilizer or granular pesticide to an agricultural field.

[0012] The storage container can be a central storage container from which granular material can be conveyed to at least one sowing device. Two or more sowing devices can also be provided. This allows several seed rows to be formed simultaneously.

[0013] The central dosing device can, in particular, be a volumetric central dosing device. The feed rate of the central dosing device can, in particular, depend on its speed. For example, the central dosing device can comprise one or more rotary valves.

[0014] The first pneumatic conveying channel can open, particularly centrally, into the distribution head, which has several outlet lines, each leading to a sowing device. In the distribution head, the first pneumatic conveying channel can thus split into several second pneumatic conveying channels, each leading to one of the sowing devices.

[0015] The at least one sowing device can, in particular, comprise a singling unit, wherein the singling unit in particular comprises a collecting container for granular material. The at least one air outlet opening can, in particular, be provided in the collecting container.

[0016] In particular, a plurality of air outlet openings can be provided, in particular two or more air outlet openings. It is also conceivable to provide a plurality of air outlet openings in the form of an air outlet grille or air outlet screen. The air outlet openings of the air outlet grille or air outlet screen can, in particular, be arranged at regular intervals. In particular, this allows several rows and columns of air outlet openings to be formed.

[0017] The size, in particular the diameter, of the at least one air outlet opening can be adapted to the size of the grains of the granular material. In particular, the size, in particular the diameter, of the at least one air outlet opening can be smaller than the average dimension of a grain of the granular material.

[0018] The at least one air outlet opening can be circular. In this case, the size of the air outlet opening corresponds to the diameter. However, other geometries are also possible. In this case, the largest dimension of the air outlet opening can be used as the size of the air outlet opening.

[0019] The blocking element for blocking the at least one air outlet opening can be a valve, in particular a 2 / 2-way solenoid valve. This allows for simple and efficient control of the air flow through the at least one air outlet opening.

[0020] The metering device can, in particular, be designed such that the position of the blocking element depends on the size of the buffer and / or the quality of the metering by the seeding device. This allows the refilling of the seeding device with granular material to be controlled or regulated as needed.

[0021] To control or regulate the blocking element, the sowing device can include a control element or be connected to a control element. The control element can be, for example, an on-board computer of a seed drill.

[0022] The sowing device can in particular comprise a sensor arrangement with which the size of the buffer and / or a parameter dependent on the size of the buffer can be determined, wherein the blocking element, in particular its position, can be controlled or regulated depending on the specific size of the buffer and / or on the specific parameter.

[0023] The "size" of the buffer can be understood herein as any specification that is proportional to the number of grains of the granular material in the buffer. For example, the size of the buffer can indicate the spatial extent of the buffer in at least one direction. Alternatively or additionally, the size of the buffer can also indicate the mass and / or number of grains of the granular material in the buffer.

[0024] The buffer itself can be defined, in particular, as a reservoir of granular material that is directly or indirectly available to the sowing device for extracting granular material and depositing it on the agricultural field. This buffer can be fed with granular material from the storage container via the first pneumatic conveying channel, the distribution head, and the second pneumatic conveying channel.

[0025] According to the invention, the central dosing device can be regulated or controlled so that a desired pressure is obtained.

[0026] The desired pressure can range from a minimum pressure to a maximum pressure. A minimum pressure occurs when all air outlets of the sowing device are clear, meaning the buffer is essentially empty. A maximum pressure, on the other hand, occurs when all air outlets are closed, meaning the buffer is completely full. In this case, the pressure can also correspond to a purely static pressure, whereas otherwise a combination of dynamic and static components is usually present.

[0027] The regulation or control of the central dosing device can in particular comprise regulation or control of a speed or flow rate of the central dosing device.

[0028] The first pneumatic conveying channel can, in particular, be connected to a blower, wherein the sensor unit is arranged and / or configured such that the pressure in the area between the blower and the central dosing device can be determined. In other words, the blower pressure can be determined.

[0029] Alternatively or additionally, the sensor unit can be arranged and / or designed such that the pressure in the first pneumatic conveying channel can be determined in a region between the central dosing device and the distribution head, i.e. downstream of the central dosing device.

[0030] If the sensor unit is arranged and / or configured such that the pressure and / or volume flow in the second pneumatic conveying channel can be determined, the dosing device can be configured such that measured values ​​from all second conveying channels are taken into account for regulating or controlling the central dosing device. Even if the buffer of one seeding device is completely full, for example, this cannot be used to determine the fill level of the other seeding devices. Reducing the feed rate of the central dosing device based solely on one measured value would then be inappropriate.

[0031] Determining the pressure may also include determining a pressure difference. A pressure gauge (piezoresistive pressure sensor), for example, can be used as a sensor unit for determining the pressure.

[0032] An anemometer (e.g. ultrasonic anemometer) can be used as a sensor unit to determine the volume flow.

[0033] The invention further provides a seed drill comprising a metering device as described above. The metering device may have one or more of the above-mentioned features.

[0034] The invention also provides a method for operating a seed drill comprising a storage container for granular material, a central dosing device connected to the storage container, a first pneumatic conveying channel connected to the central dosing device for pneumatically conveying granular material to a distribution head, at least one sowing device and a second pneumatic conveying channel for pneumatically conveying granular material from the distribution head to at least one sowing device, wherein the sowing device has at least one air outlet opening which can be at least partially blocked by a buffer of granular material or by a blocking element, the method comprising the steps: Determining, by means of a sensor unit, the pressure and / or volume flow prevailing in the first pneumatic conveying channel, the second pneumatic conveying channel, and / or the distribution head; and regulating or controlling the central dosing device based on one or more measured values ​​from the sensor unit. Sensor unit, wherein the central dosing device is regulated or controlled such that a desired pressure is achieved.

[0035] The seed drill and its components may have one or more of the above-mentioned features. Regulating or controlling the central metering device may, in particular, correspond to regulating or controlling the feed rate of the central metering device. This may be achieved, for example, by regulating or controlling the speed of the central metering device.

[0036] The conveying air flow in the first and second pneumatic conveying channels can be provided, in particular, by a blower. The blower can create an overpressure in the pneumatic conveying channels. This overpressure can be maintained at a desired value by the aforementioned control or regulation system.

[0037] Further features and advantages of the invention are explained below with reference to the exemplary figures. Fig. 1 the schematic structure of an exemplary dosing device.

[0038] Fig. 1 This diagram shows the structure of an exemplary metering device for granular material, particularly for seeds. This metering device may be part of an agricultural seed drill (not shown in detail).

[0039] The device comprises a central storage container 1 for the granular material and a central dosing device 2 connected to the storage container 1, which is arranged in the Fig. 1 is only indicated schematically. The central dosing device 2 can, in particular, be a volumetric central dosing device whose feed rate is controlled by the rotational speed.

[0040] Granular material can be introduced into a first pneumatic conveying channel 3 via the central dosing device 2, in which a conveying air flow is provided by means of a blower 4, which conveys the granular material dosed via the central dosing device 2 to a distribution head 5.

[0041] The distribution head 5 has several outlet openings 6. A second pneumatic conveying channel 7 is connected to one of the outlet openings 6, for example, and leads from the distribution head 5 to a sowing device 8. The sowing device 8 is designed in this case as a singulating unit and comprises a storage container 9 in which several air outlet openings 10 are provided. A buffer of granular material can form in this storage container 10. The granular material is fed to the storage container 9 via the first pneumatic conveying channel 3, the distribution head 5, and the second pneumatic conveying channel 7.

[0042] The housing of the sowing device 8 contains a singulating element (not shown in detail here). This element removes granular material from the storage container 9 and singulates it, so that individual seeds are dispensed at an outlet opening 11 of the sowing device in a nearly constant temporal sequence. These dispensed seeds of granular material are guided via a discharge channel 12 to a sowing coulter 13, which deposits the seeds on a landscaped area. In this example, the sowing coulter 13 is designed as a disc coulter. However, it would also be possible to provide a sowing tine here.

[0043] In the illustration of the Fig. 1 only one sowing device 8 is connected to the distribution head 5. However, it is possible that a separate sowing device is connected to each outlet 6 of the distribution head 5, which in particular is arranged in accordance with the Fig. 1 shown sowing device 8.

[0044] The central dosing device 2 doses a constant feed rate per unit of time to the first pneumatic conveying channel 3. The granular material is then conveyed along the first pneumatic conveying channel 3 to the distribution head 5, into which the first conveying channel 3 opens centrally. Within the distribution head 5, the granular material is distributed among the outlet openings 6 and thus among the individual sowing devices 8. Elements can be provided in the distribution head 5 that influence the distribution of the granular material to the outlet openings 6. For example, individual outlets can be partially or completely blocked off, so that smaller quantities of granular material are fed to the respective sowing device via these outlets. In the simplest case, however, the distribution head 5 distributes the granular material fed via the first pneumatic conveying channel 3 evenly among the outlet openings 6.

[0045] The granular material thus fed to the sowing device 8 via the second pneumatic conveying channel 7 then accumulates in the collecting container 9. The higher the buffer fill level in the collecting container 9, the more air outlet openings 10 are blocked by grains. Blocked air outlet openings 10 lead to increased flow resistance of the conveying air flow, as the cross-sectional area decreases. This, in turn, leads to a pressure increase in both the second pneumatic conveying channel 7 and the distribution head 5 and the first pneumatic conveying channel 3.

[0046] Fig. 1 shows several pressure sensors 14, 15, 16, 17, 18 which can be provided alternatively or in any combination.

[0047] For example, a pressure sensor 14 can be provided to determine the air pressure in an area between the blower 4 and the central dosing device 2. A corresponding sensor 15 can be provided downstream of the central dosing device 2 alternatively or additionally. A pressure sensor 16 can also be provided in the area of ​​the distribution head 5 to determine the air pressure in the housing of the distribution head 5. Alternatively or additionally, a pressure sensor 18 can also be provided, which determines the internal pressure in a storage container 1 designed as a pressure tank.

[0048] Finally, a pressure sensor 17 can also be provided in the respective second pneumatic conveying channels 7. However, a pressure sensor 17 in the area of ​​a second pneumatic conveying channel 7 primarily allows conclusions to be drawn about the fill level in the collecting container 9 of the respective sowing device 8. Therefore, the total pressure prevailing in several, in particular all, second pneumatic conveying channels 7 branching off from the distributor head can be used to regulate or control the central dosing device 2. In this respect, each second conveying channel 7 can be provided with a corresponding pressure sensor 17, and the total pressure can be calculated by summing the individual pressures in the pneumatic conveying channels 7.

[0049] Alternatively, or in addition to pressure, it is also possible to determine the volume flow of granular material in the first pneumatic conveying channel 3, the second pneumatic conveying channel 7, and / or the distribution head 5 using one or more volume flow sensors. Alternatively, the air volume flow can be measured, in particular at the position of the sensor 14 upstream of the central dosing device 2. The more air outlet openings 10 are closed, the lower the volume flow.

[0050] It is understood that the invention is not limited to the Fig. 1 The embodiment shown is limited. In particular, different sowing devices are also possible.

Claims

1. Metering device for granular material, in particular seed, comprising: a storage container (1) for the granular material; a central metering means (2) connected to the storage container (1); a first pneumatic conveying channel (3) connected to the central metering means (2) for pneumatically conveying granular material to a distribution head (5); at least one sowing mechanism (8); and a second pneumatic conveying channel (7) for pneumatically conveying granular material from the distribution head (5) to at least one sowing mechanism (8); wherein the sowing mechanism (8) has at least one air outlet opening (10), which can be at least partly blocked by a buffer of granular material or by a blocking element; and a sensor unit (14; 15; 16; 17) is provided for determining the pressure prevailing in the first pneumatic conveying channel (3), in the second pneumatic conveying channel (7) and / or in the distribution head (5); wherein the central metering means (2) is controllable in a closed-loop or open-loop manner based on one or more measured values of the sensor unit (14; 15; 16; 17), wherein the central metering means (2) is controlled in a closed-loop or open-loop manner so that a desired pressure is obtained.

2. Metering device according to any of the preceding claims, wherein the first pneumatic conveying channel (3) is connected to a blower (4) and the sensor unit (14) is arranged and / or designed so that the pressure in the region between the blower (4) and the central metering means (2) can be determined.

3. Metering device according to claim 1, wherein the sensor unit (15) is arranged and / or designed so that the pressure in the first pneumatic conveying channel (3) in the region between the central metering means (2) and the distribution head (5) can be determined.

4. Metering device according to any of the preceding claims, wherein the sowing mechanism (8) has a plurality of air outlet openings (10) in the form of an air outlet grille.

5. Metering device according to any of the preceding claims, wherein the sowing mechanism (8) is a singling mechanism.

6. Seed drill comprising a metering device according to any of claims 1 - 5.

7. Method for operating a seed drill which comprises a storage container (1) for granular material, a central metering means (2) connected to the storage container (1), a first pneumatic conveying channel (3) connected to the central metering means (2) for pneumatically conveying granular material to a distribution head (5), at least one sowing mechanism (8) and a second pneumatic conveying channel (7) for pneumatically conveying granular material from the distribution head (5) to the at least one sowing mechanism (8), wherein the sowing mechanism (8) has at least one air outlet opening (10), which can be at least partly blocked by a buffer of granular material or by a blocking element, the method comprising the steps of: determining, by means of a sensor unit (14; 15; 16; 17), the pressure prevailing in the first pneumatic conveying channel (3), in the second pneumatic conveying channel (7) and / or in the distribution head (5); and closed-loop or open-loop control of the central metering means (2) based on one or more measured values of the sensor unit (14; 15; 16; 17), the central metering means (2) is controlled in a closed-loop or open-loop manner so that a desired pressure is obtained.