Grain separator with separating device and seed drill with grain separator

Description

[0001] The invention relates to a grain singulation device according to the preamble of claim 1 and a seed drill according to the preamble of claim 14.

[0002] Such a seed drill with a seed singulation device is described in the unpublished German application with application number 102019130231. This seed singulation device comprises, in a manner known per se, a metering chamber with a singulation disc arranged therein, having seed intake openings. A singulation airflow generated by a blower can be supplied to the metering chamber via at least one supply channel, so that seeds can be singulated by the singulation disc based on the resulting pressure difference. The seeds to be singulated are fed to the seed singulation device via a conveying channel in the form of a seed-air mixture generated by a blower and a storage container.To separate the grains from the grain-air mixture and deliver them to the singulation disc via a seed chute from the separation unit to the metering chamber for singulation, a separation unit is integrated into the conveying channel. The separation of the grains from the grain-air mixture also results in an exhaust air stream, which is routed to the grain singulation device for singulation via an exhaust air duct separate from the supply channel.

[0003] In this seed singulation device, the exhaust air duct is routed from the separator to the outside in a complex manner. To redirect the exhaust airflow to the desired point within the seed singulation device, an additional hose is required. This hose is exposed to harsh environmental conditions during the operation of the seed drill in the field and must also be reliably sealed to ensure the proper functioning of the seed singulation device. Tests have shown that this

[0004] The grain singulation device therefore requires increased maintenance.

[0005] Another grain singulation device is known from WO 2013 / 180619 A1. This describes an agricultural tool comprising a device for feeding granular material such as seeds, fertilizer or pesticide, comprising at least two metering devices.

[0006] EP 3 586 586 A1 describes a seed supply system comprising a metering device with a seed reservoir which is subjected to a metering pressure which lies within a desired pressure range.

[0007] WO 2011 / 056123 A1 describes a sowing method on a seed drill with at least one seed hopper for seed grains or the like and several tools for introducing the seed grains into the soil, wherein the seed drill has a pneumatic means in the form of at least one pressure source, such as a blower, for transporting the seed grains from the seed hopper to the tools.

[0008] From the unpublished EP 3 704 923 A1, a singulation device arranged in a housing of a seed drill is known, in which a partial flow of a pressurized airflow, which serves to transport seeds, enters the interior of the housing via a bypass channel.

[0009] Therefore, there is a need for grain singulation devices with improved exhaust air management and seed drills with such grain singulation devices.

[0010] This problem is solved according to the invention by a grain singulation device according to claim 1 and a seed drill according to claim 14.

[0011] Accordingly, the grain singulation device comprises a metering chamber and a metering disc arranged therein, at least one supply channel for directing a singulation airflow generated by a blower into the metering chamber for singulating grains by means of the singulation disc, a conveying channel for feeding the grains in the form of a grain-air mixture generated by a blower and a storage container, and a separation device associated with the conveying channel to separate the grains from the grain-air mixture and to make them available to the singulation disc for singulation via a seed chute, and to direct the resulting exhaust airflow to the grain singulation device for singulation of the grains via an exhaust air channel separate from the supply channel.

[0012] According to the invention, the exhaust air duct has an outlet opening for the outlet of the exhaust air stream and extends from the separating device through the seed shaft, so that the outlet opening opens into the metering chamber.

[0013] The invention takes advantage of the fact that, thanks to the inventive routing through the seed hopper, the exhaust air duct is advantageously protected from external environmental influences both during operation and in transport or storage positions. Maintenance requirements are thus significantly reduced. Furthermore, the separation device can be designed to be considerably more robust and airtight as a result of this measure, since a complex routing of the exhaust air duct to the outside is no longer necessary. This also contributes to the operational reliability of the seed singulation device. An additional hose, as previously required, is therefore no longer necessary, since the exhaust air duct is integrated into the seed hopper according to the invention. The blower for generating the singulation airflow and the blower for generating the seed-air mixture can advantageously be two separate blowers. Alternatively, it is conceivable to use only a single blower.

[0014] In an advantageous embodiment of the grain singulation device according to the invention, the exhaust air duct is formed as part of the seed hopper by means of a separating element. The separating element preferably extends from the separating device to the outlet opening, so that it is configured to separate the exhaust air stream from the grains separated by the separating device, in particular pneumatically. The exhaust air duct is thus integrated into the seed hopper; that is, the exhaust air duct is at least partially formed by the walls of the seed hopper and separated from the rest of the seed hopper by the separating element.

[0015] In a further advantageous embodiment of the invention, the separating element is designed as a flat component, in particular as a separating plate. This advantageously makes ideal use of the available installation space and, in particular, prevents undercuts in which deposits can form or where particles can accumulate from the outside.

[0016] The grain singulation device according to the invention is further advantageously developed in that the supply channel has an inlet opening for the singulation airflow into the metering chamber, and that the inlet opening of the supply channel and the outlet opening of the exhaust air channel are at least approximately the same distance from the singulation disc, in particular from a plane extending radially through the singulation disc. Investigations have shown that, as a result of this arrangement, the exhaust airflow and the singulation airflow complement each other in a surprisingly advantageous manner for singulating the grains. Furthermore, this measure results in particularly favorable pressure conditions in the supply channel and the exhaust air channel.

[0017] To prevent the blowing off of singulated grains adhering to the singulation disc, a further advantageous embodiment of the invention provides that the inlet opening of the supply channel is arranged such that the flow of the singulation air stream from the inlet opening does not intersect a plane extending radially through the singulation disc. The inlet opening thus points away from the singulation disc or is at least approximately parallel to it. Furthermore, this measure reduces pneumatic turbulence in the metering chamber.

[0018] To further reduce pneumatic turbulence in the metering chamber, in a further advantageous embodiment the outlet opening of the exhaust air duct is arranged such that the exhaust air stream from the outlet opening does not intersect a plane extending radially through the singulation disc. The outlet opening thus points away from the singulation disc or is at least approximately parallel to it, so that particles adhering to the singulation disc are not captured by the exhaust air stream and blown off the disc. Preferably, the outlet opening is arranged such that the direction of the exhaust air stream intersects at least approximately the central axis of the singulation disc.

[0019] In a further advantageous embodiment of the grain singulation device according to the invention, the separation device comprises an element that is at least partially air-permeable for separating the grain-air mixture into grains and exhaust air, which is preferably designed as a sieve element. The air-permeable element is particularly preferably cylindrical. In particular, the element that is at least partially air-permeable can be a tubular sieve element.

[0020] In a further particularly advantageous embodiment of the grain singulation device according to the invention, the conveying channel has a conveying outlet from which the grain-air mixture is transferred, in particular to the separating device. The conveying outlet is located at a distance of less than twice the diameter of the conveying channel from the air-permeable element in the direction of gravity. When the grain singulation device is used as intended, the separating device is arranged above the metering chamber, so that the separated grains can be supplied to the singulation disc, in particular by gravity, through the seed chute and a shut-off valve. In intended use, the conveying channel is preferably fed to the separating device from above, so that the grains enter the separating device by gravity and cannot cause blockages in the conveying channel.

[0021] To ensure that the at least partially air-permeable element is at all times at least partially free of seeds and thus remains air-permeable, in a further advantageous embodiment the conveying outlet is arranged at least partially below the air-permeable element in the direction of gravity. The at least partially air-permeable element thus remains at least approximately free of seeds above the conveying outlet. Advantageously, this prevents at least approximately no pneumatic back pressure from building up on the separated seeds in the seed hopper, thus preventing bridging and blockages.

[0022] To facilitate the cleaning, maintenance and replacement of the at least partially air-permeable element, a further advantageous embodiment of the grain singulation device according to the invention provides that the at least partially air-permeable element can be removed without tools from a, preferably positive-locking, attachment on the separation device.

[0023] In a further advantageous embodiment of the grain singulation device, the exhaust air duct connects directly to the at least partially air-permeable element. The exhaust air flow is thus transferred to the exhaust air duct with virtually no leakage, allowing the largest possible volume of air to be used for singulating the grains. The efficiency of the grain singulation device is therefore advantageously increased.

[0024] To facilitate user control of the separating device, a further advantageous embodiment of the grain singulation device according to the invention provides that the separating device has a viewing window for visual inspection of the at least partially air-permeable element. The grains to be singulated are regularly coated with a so-called pickling agent, which can detach from the grains during operation and clog the separating device, in particular the at least partially air-permeable element. This measure makes it easier for the user to avoid malfunctions. The separating device can be designed in two parts, preferably an upper and a lower part. The viewing window can be arranged on the upper side, preferably in the upper part, of the separating device, so that the user can view it particularly easily and conveniently from above.Preferably, the top part is made of transparent material so that the entire top part can serve as a viewing window.

[0025] In a further advantageous embodiment of the grain singulation device according to the invention, the conveying channel has a conveying outlet from which the grain-air mixture is transferred, in particular to the separating device. The conveying outlet is located at a distance from the lower edge of the separating device and / or the seed hopper that is at most four times the diameter of the conveying channel. Preferably, the distance between the conveying outlet and the lower edge of the separating device and / or the seed hopper is less than four times the diameter of the conveying channel. The separating device thus has a particularly compact design. Furthermore, as a result of this measure, the pneumatic pressure and the pressure exerted by the weight of the grains themselves on the separated grains in the seed hopper are reduced, which advantageously prevents bridging and blockages.

[0026] The problem is further solved by a seed drill with at least one blower, at least one hopper for granular material, and at least one grain singulation device, wherein the at least one blower is configured to generate at least one singulation airflow and / or at least one grain-air mixture flow with grains stored in the hopper. According to the invention, the at least one grain singulation device is designed according to at least one of the preceding embodiments. For the advantages and further developments of the invention, reference is made to the embodiments of the grain singulation device.

[0027] Preferably, the seed drill has a plurality of seed singulation devices, wherein the seed drill comprises a corresponding plurality of supply channels and conveying channels to supply each seed singulation device with a singulation airflow and a seed-air mixture flow. It is conceivable that the seed drill supplies at least two seed singulation devices with a single conveying channel between at least one of the at least two seed singulation devices and the hopper containing the blower, wherein the seed-air mixture flow from the seed singulation device connected to the conveying channel can be at least partially transferred to the at least one further seed singulation device by means of an intermediate conveying channel. The intermediate conveying channel can be designed as a Y-shaped intermediate piece or comprise such an intermediate piece.It is also conceivable that the seed drill has separate conveying channels and / or supply channels for each seed singulation device. The seed drill can have a blower to generate the singulation air streams and the seed-air mixing streams, or it can provide the singulation air streams and seed-air mixing streams by means of separate blowers. The hopper can have a metering device for the controlled dispensing of the quantity of seeds into the at least one conveying channel. The seed drill can have a distribution unit for the seed-air mixing stream, to which at least one blower and at least one hopper are connected, and from which a plurality of conveying channels extend to the seed singulation devices. The seed drill can have two or more hoppers; at least one hopper can be used for storing fertilizer.

[0028] Further details of the invention can be found in the description of the example and the drawings. The drawings show Fig. 1 a schematic seed drill with a grain singulation device according to the invention, Fig. 2 a grain singulation device according to the invention in perspective detail view, Fig. 3 the grain singulation device in sectional view, and Fig. 4 a further embodiment of a grain singulation device in sectional view.

[0029] A seed drill 1 according to the invention is shown in a schematic view in Fig. 1The seed drill 1 comprises a blower 2, a hopper 3 for granular material (in this case, seed to be singulated), and a plurality of seed singulation devices 4, of which only three of the plurality of seed singulation devices 4 are shown by way of example. The blower 2 is configured to generate a singulation airflow 5 and a seed-air mixture 6, which divides into several seed-air mixtures 6, with seed grains stored in the hopper 3. In an alternative embodiment, not shown, it is conceivable that separate blowers 2 are provided for generating the singulation airflow 5 and the seed-air mixture 6. From the blower 2 and the storage container 3, a singulation air stream 5 and a grain-air mixing stream 6 are supplied to each of the individual grain singulation devices 4, so that seed grains and a singulation air stream 5 are available for the grain singulation devices 4 to work on.

[0030] The grain singulation devices 4 operate as follows: The grain singulation device 4, as shown in Fig. 2The unit shown has a metering chamber 7 with a singulation disc 8 arranged therein. The singulation airflow 5 generated by the blower 2 can be supplied to the metering chamber 7 via a supply channel 9. The singulation airflow 5 ensures, in a manner known per se, that seeds adhere to the singulation disc 8 at regular intervals and are thus singulated. A conveying channel 10 is provided to supply the seed singulation device 4 with seeds for singulation. The seeds are fed via the conveying channel 10 in the form of the seed-air mixture 6 generated by the blower 2 and the storage container 3.A separation device 13 is provided in order to separate the seeds from the grain-air mixture 6 and to make them available to the singulation disc 8 via a seed chute 11 for singulation, and to also direct the resulting exhaust air flow 15 to singulation via an exhaust air duct 12 separate from the supply duct 9.

[0031] How Fig. 3As shown, the exhaust air duct 12 has an outlet opening 14 for the discharge of the exhaust air stream 15 into the metering chamber 7. The exhaust air duct 12 also extends from the separator device 13 through the seed hopper 11, so that the outlet opening 14 opens directly into the metering chamber 7. The exhaust air duct 12 is thus integrated into the seed hopper 11, which has the advantage that it is not exposed to the ambient conditions and is therefore more durable. A separating element 16 is provided to integrate the exhaust air duct 12 into the seed hopper 11. The exhaust air duct 12 is formed as part of the seed hopper 11 by means of the separating element 16, which is designed as a flat separating plate, insofar as the exhaust air duct 12 is at least partially formed by the walls of the seed hopper 11.The separating element 16 extends from the separating device 13 to the outlet opening 14, so that it is designed to pneumatically separate the exhaust air stream 15 from the grains separated by means of the separating device 13.

[0032] The supply channel 9 has an inlet opening 17 for the outlet of the singulation airflow 5 into the metering chamber 7. In order to create particularly favorable pressure conditions between the exhaust airflow 15 and the singulation airflow 5, it is provided that the inlet opening 17 of the supply channel 9 and the outlet opening 14 of the exhaust air channel 12 have at least approximately the same distance A to the singulation disc 8 or to a plane E that extends radially through the singulation disc 8.

[0033] To prevent isolated grains already adhering to the singulation disc 8 from being blown off again, the outlet opening 14 is arranged such that the flow of the exhaust air stream 15 from the outlet opening 14 does not intersect with the plane E. Fig. 3 As shown, the outlet opening 14 is oriented such that the exhaust air stream 15 is introduced into the metering chamber 7 at least approximately parallel to the singulation disc 8. In this grain singulation device 4, the exhaust air stream 15 is designed to intersect the central axis of the singulation disc 8. In an embodiment not shown, it would be conceivable for the outlet opening 14 to point away from the singulation disc 8. Furthermore, the inlet opening 17 of the supply channel 9 is arranged such that the flow of the singulation air stream 5 from the inlet opening 17 does not intersect the plane E, which extends radially through the singulation disc 8.

[0034] As the Fig. 2 and 3As further shown, the separating device 13 has an element designed as a cylindrical sieve element 18 that is at least partially air-permeable. This sieve element 18 is designed to separate the grain-air mixture 6 into grains and exhaust air stream 15. The sieve element 18 is arranged at least approximately transversely, preferably obliquely, in the separating device 13 and is designed such that the seeds to be separated cannot pass through it and thus enter the seed hopper 11 by gravity. The exhaust air stream 15 resulting from the separation, however, can pass through the sieve element 18 and enter the exhaust air duct 12 immediately adjacent to the sieve element 18.To ensure that the sieve element 18 is not completely covered by seeds, thus preventing or even blocking the passage of the exhaust air stream 15, the conveying channel 10 is provided with a conveying outlet 19, from which the seed-air mixture is transferred to the separating device 13. This outlet is located at least partially below the sieve element 18 in the direction of gravity. This allows the exhaust air stream 15 to be reliably discharged through the exhaust air channel 12 at all times, advantageously preventing at least nearly any back pressure acting on the seeds in the seed hopper 11. The conveying outlet 19 is positioned at a smaller vertical distance from the central axis of the singulation disc 8 than at least parts of the sieve element 18.In a further embodiment, not shown, the conveying opening 19 is arranged in the direction of gravity at a distance of less than twice the diameter of the conveying channel 10 from the sieve element 18. This distance measures upwards from the sieve element 18 against the direction of gravity to the conveying opening 19, so that the separation device 13 is also compact in this embodiment, which is not shown.

[0035] When used as intended, the seed singulation device 4 is typically arranged such that the separating unit 13 is located above the metering chamber 7. The separated seeds can thus be conveyed by gravity through the seed chute 11 and a shut-off valve 20 to the singulation disc 8. The conveying channel 10 is typically fed to the separating unit 13 from above, so that the seeds cannot come to rest in the conveying channel 10 within the seed-air mixture.

[0036] In this grain singulation device 4, the conveying opening 19 is arranged such that it has a distance B from the lower edge of the separating device 13 and the upper edge of the seed chute 11, which is at most four times the diameter of the conveying channel 10. Preferably, the diameter corresponds to the clear opening from which the grain-air mixture is transferred to the separating device 13, in particular the diameter of the conveying opening 19. It is especially preferred that the distance B is at most twice the diameter of the conveying channel 10.

[0037] The conveying channel 10 further comprises a Y-shaped intermediate piece 21 at its connection to the separating device 13. Alternatively or additionally, the conveying outlet 19 has a distance C from the Y-shaped intermediate piece 21 of the conveying channel 10, which corresponds to a maximum of twice the diameter of the conveying channel 10. Preferably, the diameter corresponds to the clear width of the opening from which the grain-air mixture stream is transferred to the separating device 13, in particular, the diameter of the conveying outlet 19. The Y-shaped intermediate piece 21 can be used to direct a portion of the grain-air mixture stream 6 supplied to a grain singulation device 4 to another grain singulation device 4. Thus, at least two grain singulation devices 4 can be connected in series and supplied with the grain-air mixture stream 6 from a single conveying channel 10.In an embodiment not shown, the intermediate piece 21 can be designed in an L-shape instead of a Y-shape, so that only a single grain singulation device 4 can be supplied with grain-air mixing stream 6 by means of the intermediate piece 21.

[0038] Particularly preferably, alternatively or additionally, the intermediate piece 21 has a distance D from the lower edge of the separating device and / or the seed chute 11, which is less than six times the diameter of the conveying channel 10. In particular, the diameter corresponds to the diameter of the conveying outlet 19.

[0039] To enable simple and quick maintenance on the one hand, and reliable functional testing on the other, the sieve element 18 is designed to be removable without tools from a positive-locking attachment on the separation device 13, and the separation device 13 has a viewing window for visual inspection of the sieve element 18. In an embodiment of the grain singulation device 4 (not shown), it is conceivable that the grain singulation device 4 incorporates only one of these measures to ensure trouble-free operation.

[0040] In this grain singulation device 4, the separating unit 13 is designed in at least two parts, comprising an upper part 13A and a lower part 13B. The upper part 13A in this grain singulation device 4 is made of a transparent material, so that the entire upper part 13A can serve as a viewing window. Alternatively, in an embodiment not shown, it is conceivable that the separating unit 13 is partially made of a transparent material or has a cutout for it, thus creating a viewing window. Preferably, the viewing window is arranged on the upper side of the separating unit 13, so that a user can easily check the sieve element 18 for blockage from above. The viewing window is designed such that the sieve element 18 is visible.

[0041] Another alternative embodiment of a grain singulation device 4 is described in Fig. 4shown in a sectional view. Compared to the grain singulation device 4 described above, this grain singulation device 4 has a closing plate 22 instead of the separating element 16 designed as a divider plate. Instead of grains being separated from the grain-air mixture 6 supplied via the conveying channel 10 by means of the separating device 13, this grain singulation device 4 is configured to provide grains to the singulation disc 8 for singulation via a seed hopper (not shown) which can be connected to the seed chute 11. With otherwise identical components, this grain singulation device 4 is thus configured by means of the closing plate 22 to be operated with the seed hopper, which discharges the grains to be singulated into the seed chute 11 under the influence of gravity. The grains to be singulated consequently pass through the seed chute 11 and the shut-off valve 20 to the singulation disc 8.The singulation airflow 5 into the metering chamber 7 causes the seeds to adhere to the singulation disc 8 and thus be singulated. The exhaust air duct 12 is closed by means of the sealing plate 22 between the metering chamber 7 and the seed hopper 11, so that the seed hopper 11 serves only to supply seeds to the singulation disc 8. From a manufacturing perspective, this embodiment has the advantage that, by replacing the separating element 16 with the sealing plate 22, an otherwise identical seed singulation device 4 can be converted for operation with a seed hopper instead of a conveying channel 10 with an associated separating device 13. Furthermore, seed singulation devices 4 can be easily converted for use with a separating device 13 or a seed hopper by replacing the separating element 16 with the sealing plate 22.

[0042] The closing plate 22 can preferably be inserted into the grain singulation device 4 in a way that allows for manual removal. The separating element 16 can preferably be removed manually. Alternatively, it is conceivable that the separating element 16 and the closing plate 22 are one and the same component, which can be pivoted between a first position as a separating element 16 to form the exhaust air duct 12 and a second position to close the exhaust air duct 12. The grain singulation device 4 can have an interface to which the separating element 16 and the closing plate 22 can be attached. The interface can be located in the seed hopper 11. The separating element 16 and / or the closing plate 22 can be fastened in the grain singulation device 4 by means of a quick-release connection. Alternatively, it is conceivable that the separating element 16 and the closing plate 22 are the same component, which is pivotably arranged at the interface. Reference symbol list

[0043] 1 Seed drill 2 Blower 3 Hopper 4 Singulation device 5 Singulation airflow 6 Grain-air mixing flow 7 Metering chamber 8 Singulation disc 9 Supply duct 10 Conveyor duct 11 Seed chute 12 Exhaust duct 13 Separation device 13A Top part 13B Bottom part 14 Outlet opening 15 Exhaust air flow 16 Separating element 17 Inlet opening A Distance E Level 18 Sieve element 19 Conveyor outlet 20 Shut-off gate B Distance C Distance 21 Intermediate piece D Distance 22 Closing plate

Claims

1. Grain singling apparatus (4) comprising - a metering chamber (7) and a singling disk (8) arranged therein; - at least one supply duct (9) for feeding a singling air flow (5) generated by a fan (2) into the metering chamber (7) for singling grains by means of the singling disk (8); - a conveying duct (10) for supplying the grains in the form of a mixed grain / air flow (6) generated by a fan (2) and a storage container (3); - a separating device (13), which is associated with the conveying duct (10), for separating the grains from the mixed grain / air flow (6) and proving them via a seed chute (11) to the singling disk (8) for singling, and feeding the resulting exhaust air flow (15) via an exhaust air duct (12) separate from the supply duct (9) to the grain singling apparatus (4) for singling the grains, the exhaust air duct (12) having a discharge opening (14) for outflow of the exhaust air flow (15), characterized in that the exhaust air duct (12) extends from the separating device (13) through the seed chute (11), so that the discharge opening (14) opens into the metering chamber (7).

2. Grain singling apparatus (4) according to claim 1, characterized in that the exhaust air duct (12) is formed as part of the seed chute (11) by means of a separating element (16).

3. Grain singling apparatus (4) according to claim 2, characterized in that the separating element (16) is designed as a planar component, in particular as a separating plate.

4. Grain singling apparatus (4) according to at least one of the preceding claims, characterized in that the supply duct (9) has a feed opening (17) for outflow of the singling air flow (5) into the metering chamber (7), in that the feed opening (17) of the supply duct (9) and the discharge opening (14) of the exhaust air duct (12) are at approximately the same distance (A) from the singling disk (8), in particular from a plane (E) which extends radially through the singling disk (8).

5. Grain singling apparatus (4) according to at least one of the preceding claims, characterized in that the feed opening (17) of the supply duct (9) is arranged such that a flow of the singling air flow (5) from the feed opening (17) has no point of intersection with a plane (E) which extends radially through the singling disk (8).

6. Grain singling apparatus (4) according to at least one of the preceding claims, characterized in that the discharge opening (14) of the exhaust air duct (12) is arranged such that a flow of the exhaust air flow (15) from the discharge opening (14) has no point of intersection with a plane (E) which extends radially through the singling disk (8).

7. Grain singling apparatus (4) according to at least one of the preceding claims, characterized in that the separating device (13) has an at least partially air-permeable element (18) for separating the mixed grain / air flow (6) into grains and exhaust air flow (15), which element is preferably designed as a sieve element (18), particularly preferably as a cylindrical sieve element.

8. Grain singling apparatus (4) according to claim 7, characterized in that the conveying duct (10) has a conveying outlet (19) from which the mixed grain / air flow (6) is transferred in particular to the separating device (13),in that the conveying outlet (19) is at a distance of less than twice a diameter of the conveying duct (10) from the air-permeable element (18) in the direction of gravity.

9. Grain singling apparatus (4) according to claim 8, characterized in that the conveying outlet (19) is arranged at least partially below the air-permeable element (18) in the direction of gravity.

10. Grain singling apparatus (4) according to at least one of claims 7 to 9, characterized in that the at least partially air-permeable element (18) can be removed without tools from a preferably form-fitting fastening on the separating device (13).

11. Grain singling apparatus (4) according to at least one of claims 7 to 10, characterized in that the exhaust air duct (12) is directly connected to the at least partially air-permeable element (18).

12. Grain singling apparatus (4) according to at least one of claims 7 to 11, characterized in that the separating device (13) has a viewing window for visual inspection of the at least partially air-permeable element (18).

13. Grain singling apparatus (4) according to at least one of the preceding claims, characterized in that the conveying duct (10) has a conveying outlet (19) from which the mixed grain / air flow (6) is transferred in particular to the separating device (13), in that the conveying outlet (19) is at a distance (B) from the lower edge of the separating device (13) and / or from the seed chute (11) that corresponds to at most four times the diameter of the conveying duct (10).

14. Seed drill (1) comprising at least one fan (2), at least one storage container (3) for granular material, and at least one grain singling apparatus (4), the at least one fan (2) being designed to generate at least one singling air flow (5) and / or at least one mixed grain / air flow (6) with grains stored in the storage container (3),characterized in that the at least one grain singling apparatus (4) is designed according to at least one of claims 1 to 13.