Method and device for seed singulation by means of differential pressure

Abstract

Blowing the process air (38) successively through an injection nozzle (28) and a receiving nozzle (30) into a diffusor (32) that opens out in the seed store area (4), wherein between the injection nozzle (28) and the receiving nozzle (30) there is an opening (34) which leads towards the negative-pressure chamber (10) and through which air (46) from the negative-pressure chamber (10) is drawn into the air stream of the process air (38), produces a particularly effective and energy-efficient system for generating a differential pressure (P3 - P2), which can be used for the seed singulation.

Description

[0001] Method and device for seed singulation by means of differential pressure

[0002] The present invention relates to a method and a device for seed singulation by means of differential pressure.

[0003] The document US 6,142,086 describes a device for seed singulation with a rotating drum, on the inside of which a negative pressure is created and which has a number of holes on its outer shell. Due to the negative pressure acting in the area of ​​the holes, seed grains located in a seed storage area adjacent to the drum adhere to the drum. In this system, a blower generates an overpressure, which is present in the seed storage area on the outside of the drum. At the same time, air is sucked out of the interior of the drum via a vacuum line opening into the interior of the drum, creating a negative pressure there. If a negative pressure is created inside the drum in this way, considerable volumes of air must be moved, which is associated with considerable effort.The pressure equalization between the overpressure and the underpressure side of the drum also results in considerable losses of process air, which require oversized fans for the actual process and an increased.

[0004] Requires energy expenditure. A device for seed singulation is also known from US Pat. No. 4,915,258. A first chamber, subjected to a negative pressure, is covered by a rotating, driven disc, on the surface of which there are a number of holes. A seed storage area is formed in a second chamber, located on the opposite side of the disc. The seed grains held there adhere to the holes in the disc only due to the vacuum in the chamber, because no special pressure is built up in the seed storage area by an air supply fan. Although this eliminates the need for a separate pressure fan, there is no air flow to assist the removal of the individual grains when the seed is discharged into the downpipe.In order to ensure that the seeds adhere reliably to the disc, a significant negative pressure must be created on the side of the disc facing away from the seed storage area.

[0005] The document DE 2 401 306 A1 discloses a rotating wheel for seed singulation with a number of radially projecting tubes in which a vacuum is created by an air stream guided past the inner ends by means of a Bernoulli effect in order to suck in a grain at the outer ends of the tubes and take it from a grain supply.

[0006] There is no pressure chamber. Overall, with the devices known from the state of the art, considerable effort must be made to generate a negative pressure in the vacuum chamber sufficient for reliable grain singulation. If a particular overpressure is to be generated in the seed storage area, an additional blower is required, which generates additional process air losses and causes increased energy consumption. The known air systems also require a considerable amount of space in the machine that could be better used for other purposes. The comparatively high air throughput of the known air systems also creates a risk of contamination of the machine components via the process air and environmental pollution from moving dust particles and / or particles of pesticides that may be contaminated with the seed.

[0007] It is the object of the present invention to reduce the disadvantages of the seed singulation methods known from the prior art and the devices used for the methods.

[0008] The problem is solved for a seed singling method with the features of claim 1 and for a device for seed singling with the features of claim 8.

[0009] According to the invention, a method for seed singulation by means of differential pressure is provided for at least one seed singulation device, in which a singulation element having seed receiving holes at least co-forms a, in particular rotating, vacuum chamber, wherein the

[0010] The outer side facing away from the vacuum chamber receives seed in a seed storage area by generating an internal pressure in the vacuum chamber which is lower than the external pressure on the outside thereof, which sucks the seed at the seed receiving holes until it is released into a seed outlet, and wherein the internal pressure in the vacuum chamber of the at least one seed singling device is generated by means of a differential pressure generating device in the form of at least one jet pump.

[0011] The differential pressure acts via the singulating element, enabling the seeds to be singulated. A jet pump is a pump in which a pumping effect is generated by a fluid jet, for example, air or process air. The fluid jet can suck in, accelerate, and compress or convey another medium, such as air in a vacuum chamber, through momentum exchange. The differential pressure generating device in the form of the jet pump can be connected to a vacuum chamber via a suction line and / or a pressure line or the diffuser to an outside surface in order to generate a pressure difference across a singulating element.

[0012] By using a differential pressure generation device in the form of a jet pump, a particularly powerful and energy-efficient system is created for generating a differential pressure that can be used for seed singulation. The amount of air required to feed the injection nozzle is comparatively low compared to previously known systems. Using the Bernoulli effect, the volume of process air can be increased with additional air along the flow path. The process air is sucked out of the vacuum chamber. By sucking the additional air volume from the vacuum chamber in addition to the process air, the exhaust air sucked out there using the Bernoulli effect creates a negative pressure. The negative pressure is created exactly where it is needed for seed singulation.The air flowing from the seed storage area, for example, through the seed intake holes into the vacuum chamber, is drawn directly back into the process air as recirculated air and then returned to the seed storage area. This increases the pressure gradient between these areas accordingly. Finally, the efficiently increased air volume is blown into the seed storage area via a diffuser, creating a pressure increase precisely there, if desired. The supplied process air essentially corresponds to the air or shot air exiting through an outlet opening of the singulating device along with the singulated seed.

[0013] Due to this multiple increase in efficiency, namely at several points in the air system of a seed singulation system, it is possible to make the fans smaller and thus reduce the drive power required. The cross-sections of the hoses for the air supply, i.e. the pressure lines, can be selected smaller and thus more cost-effectively. The inventive design of the method and device for seed singulation results in a comparatively high differential pressure with comparatively low operating expenditure when the seed intake holes are essentially closed by seed. This differential pressure can be effectively used to suck in the seed. The overpressure that can be built up in the seed storage area can also be used to support seed application.

[0014] The increased efficiency of the air system allows the seed singulation system to operate with a lower air flow rate. This reduces the flow speed of the recirculating air drawn in from the area surrounding the seed drill, thus reducing the risk of dirt particles suspended in the recirculating air being sucked into the seed singulation system components, which can impair the quality of the seed singulation. The air system can be used for all types of seeds.

[0015] Preferably, the differential pressure generating device in the form of a jet pump is fluidly connected to several seed singulating devices, in particular their vacuum chambers. The jet pump generates an internal pressure in the vacuum chambers that is lower than the external pressure on their exterior. A jet pump or

[0016] The differential pressure generating device can be connected to one or more seed singulating devices via one or more suction lines and / or pressure lines. At least one negative pressure can be generated via the suction line in, in particular, at least one negative pressure chamber. This enables seed singulation.

[0017] In a further preferred embodiment of the method, in the differential pressure generation device in the form of a jet pump, process air provided by a process air flow generator flows through an injection nozzle and is directed to a collecting nozzle with a diffuser. In the process air flow direction, between one end of the injection nozzle and one beginning of the collecting nozzle, there is at least one opening that is fluidly connected to the interior of the at least one vacuum chamber. Thus, air from the vacuum chamber is drawn along with the process air and thereby expelled from the vacuum chamber. This allows a differential pressure to develop between the interior of the vacuum chamber and its exterior.

[0018] For the seed singulation process, a differential pressure is generated. The differential pressure acts on seed receiving holes formed on a singulation element. The singulation element, through a particularly rotating vacuum chamber, at least co-creates a low-pressure region, for example, by forming a side wall of the vacuum chamber. The outer side of the singulation element, facing away from the interior of the vacuum chamber, receives seed in a seed storage area during a rotating movement. An internal pressure is generated in the vacuum chamber that is lower than the external pressure on its exterior, via which the grains held in the seed storage area are sucked into the seed receiving holes.The seed intake holes are shaped and sized to suit the specific grains to be separated, so that a single grain is sucked in and held at each seed intake hole, but cannot be sucked through the hole. The grains adhering to the seed intake holes are carried along in the direction of rotation by the rotating movement of the singling element until they reach a discharge point, from where they are discharged into a seed outlet.

[0019] The internal pressure in the vacuum chamber, which is lower than the external pressure, is created by injecting process air through an injection nozzle extending into the interior of the vacuum chamber. The air flow from this air is then directed out of the vacuum chamber again by a collecting nozzle with a diffuser. In the direction of the process air flow, there is at least one opening between the end of the injection nozzle and the beginning of the collecting nozzle. Through this opening, air from the interior of the vacuum chamber is sucked along with the process air in the manner of a jet pump and thus transported out of the vacuum chamber. The air flow blown into the interior of the vacuum chamber by the injection nozzle is generated by one or more process air flow generators, for example blowers, side channel blowers or compressors, whereby the air is sucked in from the ambient air and forced into a line that opens into the injection nozzle.The process air flow generator can be arranged away from the components of the seed singulation system at a different location on a seed drill equipped with the seed singulation system according to the invention. However, multiple process air flow generators can also be provided, for example one side channel compressor per row of the seed drill in question or one for every two or four rows, etc. This allows the required line lengths to be kept short and pressure losses to be reduced. The injection nozzle and the collecting nozzle make use of the Bernoulli effect in their function. The injection nozzle has a cross-sectional constriction upstream of the outlet opening as seen in the direction of process air flow in order to influence the flow of process air as it passes between the closed space inside the injection nozzle and the free space downstream of the outlet opening of the injection nozzle as seen in the direction of process air flow.At the narrowest point of the injection nozzle, the dynamic pressure or back pressure is maximum and the hydrostatic pressure minimum. The speed of the process air flowing through the injection nozzle increases in proportion to the cross-sections as it flows into the narrower part because, according to the law of continuity, the same mass flows through the entire pipe per unit time. In the area of ​​the outlet opening, the process air flows out of the injection nozzle at a high flow velocity and reduced pressure. Due to the reduced pressure in the air flow of the process air in the area of ​​the outlet opening of the injection nozzle, air in the vacuum chamber is sucked into the air flow flowing out of the injection nozzle through the opening located between the end of the injection nozzle and the beginning of the collecting nozzle, similar to a Venturi nozzle, and entrained.The air sucked out of the vacuum chamber reduces the internal pressure in the vacuum chamber, so that a differential pressure develops between the inside of the vacuum chamber and its outside.

[0020] To ensure that the air flow of the process air flowing over the injection nozzle does not

[0021] vacuum chamber and thereby equalizes the differential pressure again, the air flow is directed back out of the vacuum chamber by the collecting nozzle with diffuser behind the opening as seen in the direction of flow of the process air. The collecting nozzle also has a nozzle section with a cross-sectional constriction in order to influence the flow of the process air in the direction of flow of the process air. As a result of the air flowing into the air flow in the area of ​​the opening from the vacuum chamber, the flow velocity of the process air in this area has slowed down again and the hydrostatic pressure has decreased. In order to accelerate the flow velocity of the process air again, a cross-sectional constriction is formed in the collecting nozzle, at the narrowest point of which the dynamic pressure or the back pressure is at a maximum and the hydrostatic pressure in the collecting nozzle is at a minimum.Here, too, the velocity of the process air flowing through the injection nozzle increases in proportion to the cross-sections as it enters the narrower section, because according to the law of continuity, the same mass flows through the entire pipe per unit time. In this way, the process air flow, enriched with the air drawn from the vacuum chamber, is directed out of the vacuum chamber via the collecting nozzle, maintaining the reduced internal pressure in the vacuum chamber.

[0022] The diffuser slows the flow velocity of the process air in this flow section, thereby increasing the hydrostatic pressure in the process air. The flow deceleration is achieved by a continuous or discontinuous expansion of the flow cross-section in the direction of flow of the process air through the diffuser. The diffuser can be directly connected to the cross-sectional constriction of the collecting nozzle, thereby achieving an advantageous, space-saving arrangement of the components. When the diffuser opens into the seed storage area, the pressure energy generated by the diffuser increases the hydrostatic pressure prevailing in the seed storage area.

[0023] A pressure increase in the seed storage area generated by the process air in turn increases the differential pressure that results in the area of ​​the seed receiving holes in the singling element due to the difference in the hydrostatic pressure of the air in the vacuum chamber and in the seed storage area.

[0024] At the beginning of singulation, a slightly higher initial inlet pressure must be provided, as more air flows back into the vacuum chamber through unclosed seed intake holes. However, with closed holes, the pressure requirement decreases, and the process air output required during stationary operation is low.

[0025] The components of the seed singulation system can be arranged in a housing. In addition to the components of the seed singulation system, the housing preferably also encloses the seed storage area. The seed storage area is preferably located on the seed-receiving side of the singulation element. An increased pressure in the seed storage area can be easily maintained if the seed singulation device is surrounded by an at least substantially closed housing. The housing preferably comprises the vacuum chamber, the seed storage area, and the singulation element. The housing must have an opening so that process air can be guided from the outside into the seed storage area. Furthermore, the housing must have a seed outlet through which the singulated grains can be discharged into the seed line, a seed tube, or a discharge line. The housing can also be open or pressure-tight.

[0026] The pressure conditions in the seed singulation system can be easily adjusted and coordinated through appropriate design, dimensioning, and coordination of the performance of the injection nozzle, the collecting nozzle, and the diffuser. Suitable sizes can be selected for the diameters of the line sections of the injection nozzle, the collecting nozzle, and the diffuser, as well as for the size of the cross-sectional constrictions in the injection nozzle and the collecting nozzle. The injection nozzle, the collecting nozzle, and the diffuser can be arranged at suitable distances from one another. The shape, arrangement, and size of the opening between the injection nozzle and the collecting nozzle is designed so that a sufficiently large amount of air is extracted from the vacuum chamber. The opening can, in particular, be designed in the form of an annular gap in order to ensure the inflow of air from the vacuum chamber to the process air as evenly as possible and with the lowest possible flow resistance.The injection nozzle and the collecting nozzle can also be connected. The opening can be formed by holes in the transition area. The design and dimensioning of the fan used to supply the process air to the injection nozzle also influences the pressure conditions in the seed singulation system.

[0027] The pressure of the process air supplied to the injection nozzle, as well as the delivery volume of the blower, can be optionally designed to be variable in order to influence the differential pressure during seed singulation and the amount of air used for seed singulation. The factors influencing the respective pressures within the seed singulation system can be adjustable or variable, such as the corresponding line cross-sections, cross-section constrictions, spacing of the components from one another, and the like. The components of the seed singulation system can be designed and adjusted to achieve a high pressure differential in the seed singulation system. However, optimization can also be aimed at minimizing the amount of air escaping from the seed singulation system. High grain velocities are not always beneficial for seed placement.By using a lower overpressure or even just atmospheric pressure in the seed storage area, the seed ejection speeds can be reduced. With a lower pressure in the seed storage area, the effort required to seal the housing surrounding the seed singulation device can also be reduced. Due to the variability of the singulation pressure, the seed singulation system according to the invention can be used in various seed drills, for example, both in seed drills that have a catching roller in the seed placement area in the soil and in seed drills that do not have a catching roller in the placement area.

[0028] The increased efficiency of the air system can be used to select smaller dimensions for the injection nozzle, the collecting nozzle, and the diffuser. This also allows for a smaller singulation element and thus the overall size of the sowing unit.

[0029] By successively blowing the process air through an injection nozzle and a collection nozzle into a diffuser opening in the seed storage area, with an opening to the vacuum chamber between the injection nozzle and the collection nozzle, through which air from the vacuum chamber is drawn into the process air stream, a particularly powerful and energy-efficient system is created for generating a differential pressure that can be used for grain singulation. The amount of air required to feed the injection nozzle is comparatively small compared to previously known systems because the Bernoulli effect allows the air volume of the process air to be increased along the flow path with additional air drawn from the vacuum chamber.By extracting the additional air volume from the vacuum chamber in addition to the process air, the exhaust air extracted there using the Bernoulli effect creates a negative pressure precisely where it is needed for seed singulation. The air flowing from the seed storage area, for example via the seed intake holes, into the vacuum chamber is sucked back into the process air as recirculated air and returned to the seed storage area. This correspondingly increases the pressure gradient between these areas. Finally, the efficiently increased air volume is blown into the seed storage area via a diffuser, creating an increase in pressure precisely there, if desired. Due to this multiple increase in efficiency, namely at several points in the air system of a seed singulation system, it is possible to make the fans smaller and thus reduce the drive power required.The cross-sections of the hoses for the air supply, i.e., the pressure lines, can be made smaller and thus more cost-effective. The inventive design of the method and device for seed singulation allows for a comparatively high differential pressure to be generated with relatively low operating costs when the seed intake holes are essentially blocked by seed. This differential pressure can be effectively used to suck in the seed. The overpressure that can be built up in the seed storage area can also be used to support seed application.

[0030] The increased efficiency of the air system allows the seed singulation system to operate with a lower air throughput. This reduces the flow speeds of the circulating air drawn in from the surroundings of the seed drill, and thus also reduces the risk of dirt particles suspended in the circulating air being sucked into the components of the seed singulation system, which could impair the quality of the seed singulation. The air system can be used for all seeds. The device according to the invention for at least one seed singulation system has at least one singulation element having seed receiving holes, which at least co-forms a, in particular rotatable, vacuum chamber. The device has a seed storage area on an outer side of the singulation element facing away from the interior of the vacuum chamber.The device further comprises a differential pressure generating device, in particular with a process air flow generator, wherein the differential pressure generating device is designed in the form of a jet pump. The jet pump is configured such that it is fluidly connected to the interior of at least one vacuum chamber of the at least one seed singling device and generates an internal pressure in the vacuum chamber that is lower than the external pressure on the outside. The differential pressure device in the form of a jet pump can generate the pressure difference required for seed singling across the singling element in an efficient and space-saving manner.

[0031] In a preferred embodiment, the differential pressure generating device in the form of a jet pump is fluidically connected to a plurality of seed singulating devices, in particular their vacuum chambers, each for generating a lower internal pressure than the outer sides thereof. This enables efficient generation of a pressure difference for seed singulation in a plurality of seed singulating devices. Several seed singulating devices can be arranged in groups, each with a

[0032] Differential pressure generating device in the form of a jet pump.

[0033] Preferably, the vacuum chamber is arranged in a housing of the seed singulating device and / or the differential pressure generating device is arranged at least partially inside and / or outside the housing. The differential pressure generating device in the form of a jet pump can be arranged at a distance from a housing of a seed singulating device and connected to it, for example, via a suction line and / or pressure line to generate a differential pressure. The differential pressure generating device can be arranged, at least partially, directly on the seed singulating device and / or the housing. For example, the diffuser can be connected directly to the housing, thereby saving lines, in particular a pressure line to the housing, and allowing optimal use of available installation space.

[0034] In a further preferred embodiment, the differential pressure generating device, which is arranged in particular outside the housing, has an injection nozzle connected to the process air flow generator and a collecting nozzle with a diffuser. In this case, in the flow direction of the process air, between an end of the injection nozzle and a beginning of the collecting nozzle, there is at least one opening which is fluidically connected to the interior of at least one vacuum chamber, in particular via a line. As a result, air from the interior of the vacuum chamber is sucked along with the process air and is thereby transported out of the vacuum chamber. Thus, a

[0035] A differential pressure is created between the vacuum chamber and its exterior. The opening can be connected to the vacuum chamber, for example, via a suction line. The generated differential pressure acts on the singulating element, allowing the seed to be singulated.

[0036] The device uses at least one singling element that has seed receiving holes and at least co-forms a, in particular rotatable, vacuum chamber. The device has a seed storage area on an outer side of the singling element facing away from the interior of the vacuum chamber. Furthermore, the device has a differential pressure generating device with a process air flow generator. The differential pressure generating device has an injection nozzle extending into the interior of the vacuum chamber and connected externally to the process air flow generator, as well as a collecting nozzle with a diffuser.The injection nozzle and the collecting nozzle with diffuser are arranged such that, in the direction of flow of the process air, the end of the injection nozzle and the beginning of the collecting nozzle face each other inside the vacuum chamber, with at least one opening being located between the end of the injection nozzle and the beginning of the collecting nozzle through which air from the interior of the vacuum chamber is sucked along with the process air and thereby conveyed out of the vacuum chamber, so that a differential pressure develops between the interior of the vacuum chamber and its exterior. The diffuser can be connected via a pressure line or directly to at least one housing or at least one seed singulating device, in particular to its seed storage area and / or the exterior. The opening can be connected to the interior of at least one vacuum chamber via a suction line.

[0037] The vacuum chamber can be housed in a housing, particularly a rotating one. The housing protects the seed singulation system from external interference. The housing creates defined conditions for trouble-free operation. The housing can be open or almost completely closed. Thus, the design of the housing allows the device to operate both as a positive pressure and negative pressure singulation system, while the differential pressure can remain constant.

[0038] According to one embodiment of the invention, the diffuser in the housing outside the vacuum chamber applies a positive pressure relative to the ambient pressure. Particularly in a virtually sealed housing, the pressure prevailing therein can be increased by the process air blown out by the diffuser.

[0039] The beginning of the collecting nozzle can have a funnel-shaped inlet area into which the end of the injection nozzle extends. The funnel-shaped inlet area directs the process air exiting the injection nozzle in the direction of the cross-sectional constriction of the collecting nozzle. At the same time, the wall of the funnel-shaped inlet area, in its extension direction, ensures good integration of the air flowing in from the vacuum chamber into the air flow of the process air. Since the incoming air is guided along the extension direction of the wall, it is moved converging towards the process air following the funnel shape. The respective air flows are thus guided in approximately the same direction. Turbulence and crossflows in the converging area are thus largely avoided. The funnel shape also creates a flow path along whose length the air flows to be converged can mix with each other.The air supplied from the vacuum chamber can thus be integrated into the process air flow without significant performance losses.

[0040] The collecting nozzle can be permanently connected to the vacuum chamber. To achieve a high differential pressure, it is desirable to create the highest possible negative pressure in the vacuum chamber. If the collecting nozzle were not permanently connected to the vacuum chamber, air from outside, particularly from an overpressure area, could flow into the vacuum chamber in the transition area between the outside of the collecting nozzle and the adjacent components of the vacuum chamber, thereby reducing the negative pressure prevailing in the vacuum chamber. The pressure difference achievable with the device, with otherwise identical components, would then be smaller, and the efficiency of the separation system would also be reduced. To prevent an inflow of air from the transition area from the collecting nozzle to the vacuum chamber, the transition area between the injection nozzle and the adjacent wall of the vacuum chamber would have to be extensively sealed if the connection were not permanent.This would require increased construction and assembly effort, and could lead to increased wear in this area. This can be avoided if the collecting nozzle is firmly connected to the vacuum chamber. The fixed connection can be designed to be gas-tight, for example by means of closed walls, abutment surfaces, and edges in the transition area. However, the collecting nozzle and the adjacent components of the vacuum chamber can also be formed in a single molded part, which is manufactured, for example, as a one-piece molded part in a tool using an injection molding process, thus avoiding joints that are not gas-tight.Several molded parts can also be connected to each other in a gas-tight manner in the respective joint area, for example, by means of gas-tight seals between the components, a gas-tight adhesive bond, or a gas-tight filler such as silicone or acrylic, which is applied to the joints in the joint area of ​​the components after their assembly. Gas-tight connections are considerably easier to achieve with fixed connections between components than with connections that allow relative movement between components.

[0041] The vacuum chamber can be cylindrical. The cylindrical shape results in uniform flow conditions inside the vacuum chamber, a constant circumferential shape during rotation of the vacuum chamber, and good integration into the shape of a housing. Bearing a cylindrical component is also inexpensive and simple. With this basic shape, the rotation axis can correspond to the main axis of inertia, thereby preventing imbalance and increased wear of the bearings and

[0042] Drives should be avoided.

[0043] The injection nozzle and the collecting nozzle can be arranged on opposite ends of the vacuum chamber. This allows both components to be mounted individually, for example, one of the components is connected to the vacuum chamber by a rotational bearing, and the other component is connected to a rotational bearing. Such an arrangement also makes it possible to design the opening area without struts, supports, webs, and the like that would disrupt the airflow.

[0044] The air mass flow conveyed in the circuit between the pressure side of the separating element and the vacuum chamber depends primarily on the length of the free jet between the injection nozzle and the collecting nozzle. If the injection nozzle is kept constant, the entire variance can be generated via the collecting nozzle, which can be connected to the separating element.

[0045] According to one embodiment of the invention, the distance between the injection nozzle and the collecting nozzle is adjustable using an adjusting device. By changing the distance between the injection nozzle and the collecting nozzle, the negative pressure in the vacuum chamber can be specifically changed and set to a desired value while maintaining a constant process air flow. The adjustment can be made, for example, using a screw thread in which the injection nozzle and / or the collecting nozzle are held. The injection nozzle and / or the collecting nozzle can be held in a desired position using a lock nut. The singling element can have the seed receiving holes in a front side of the cylindrical vacuum chamber designed as a sowing disc. The seed can rest on the side of the sowing disc in the seed singling area and can be easily carried along by the seed receiving holes.The radius of the seeding disc still leaves enough space for the diffuser, through which the process air can flow into the seed storage area. The collecting nozzle with the diffuser can be permanently connected to the seeding disc and can also be exchangeable with it. In the direction of rotation of the seeding disc, the collected seeds can be released from the seed receiving holes in an area remote from the seed singulation area and delivered to a seed outlet.

[0046] The singulating element can be designed as a seeding drum with seed receiving holes in the outer surface of the cylindrical vacuum chamber. Several rings of seed receiving holes can be arranged next to each other on the outer surface across the width of the seeding drum. With a cylindrical shape of the singulating element and the equal spacing of the seed receiving holes in the individual rings, several seed outlets can be supplied with singled seeds evenly and at the same working rate using one singulating device.

[0047] According to one embodiment of the invention, the singling element is designed as a seed disc and / or a seed drum shell and is a replaceable part of the vacuum chamber. With an replaceable seed disc and / or a replaceable seed drum shell, the seed singling device can be adapted to different seeds by simply exchanging these components. With different seed discs or seed drum shells, the seed receiving holes can be of different sizes and have a different geometry, they can be formed in a different position, the number of seed receiving holes can differ, and / or the length and / or shape of the injection nozzle and / or the collecting nozzle and / or the diffuser can vary.

[0048] The seed storage area can be formed in a housing enclosing the vacuum chamber. The housing provides defined spatial arrangements of the components relative to one another. The interior of the housing is protected against external influences such as wind, rain, stones, dirt, and the like. The housing can seal the seed storage area against pressure losses, and / or the pressure conditions and air flows within the housing can be specifically controlled and influenced via corresponding openings in the housing. If the housing is opened at least essentially only via a seed outlet, the overpressure in the housing can be used to shoot the separated seeds into the seed outlet with the escaping compressed air.

[0049] The injection nozzle can be permanently connected to the housing.

[0050] Mounting the injection nozzle on the housing, the injection nozzle can be mounted with a simple

[0051] A hose can be connected to a process air flow generator. The injection nozzle can be easily mounted on the housing in a gas-tight manner. The outer casing of the seed singulation device is robust and resistant to external influences.

[0052] The vacuum chamber can rotate around the injection nozzle. The injection nozzle essentially forms a shaft on which the vacuum chamber rotates. This arrangement results in defined geometric relationships for the flow of process air through the vacuum chamber, the flow of air within the vacuum chamber, and the inflow of air from the vacuum chamber into the process air. The rotary bearing of the vacuum chamber on the injection nozzle is structurally unproblematic. The bearing is well protected against external influences inside the housing.

[0053] According to one embodiment of the invention, the seed storage area is filled in a controlled manner via a seed feed line. In order to be able to separate seeds from a seed supply, it is a necessary but also sufficient condition that the seed supply is filled to such an extent that a sufficient number of seeds are available for separation and transport at the seed receiving holes formed on the singling element. If the seed supply is too low, it is possible that individual seed receiving holes will not be filled with seeds, which leads to gaps in the deposited seed row. However, too high a fill level is also disadvantageous because it can hinder the separation of individual seeds. With controlled filling, as much seed as is required for reliable seed singulation can be fed in continuously or intermittently. This can preferably be achieved with a conveying air stream.Suitable sensors, such as light barriers, ultrasonic sensors, or capacitive sensors, can be used to measure the seed level. Driven slides, cell wheels, and the like can be used to open and close the feeder.

[0054] The pressure in the seed intake area of ​​the housing can be additionally adjustable using an overpressure control. An overpressure situation with excessive hydrostatic pressure in the seed storage area can be prevented by an overpressure control, for example, using a pressure relief valve. If the hydrostatic pressure in the seed storage area exceeds a threshold, the pressure relief valve opens. The pressure relief valve can be adjusted to various thresholds.

[0055] According to one embodiment of the invention, the compressed air discharged from the overpressure control is recirculated into the seed supply line. The excess compressed air is thus still used to transport the seed.

[0056] According to one embodiment of the invention, a seed supply line opens into the seed storage area of ​​the housing, with the seed supply line in particular having a check valve. New seed can be supplied to the seed storage area via the seed supply line to replace seed that has been separated and deposited in the soil. The supply can be continuous, timed, controlled by sensors, or in response to a specific operating signal.

[0057] The check valve allows the supply of seed to the seed storage area, but pressure losses in the seed storage area via the seed supply line are avoided if no seed is supplied to the seed storage area for a time.

[0058] According to one embodiment of the invention, a pressure relief valve is arranged on the housing for the targeted adjustment of the pressure on the seed intake side and / or in the seed discharge area and / or in the area of ​​the seed outlet(s), wherein the pressure relief valve is connected to the seed supply line. The pressure relief valve enables the setting of a desired value for the pressure in the seed storage area on the seed intake side of the singulating element. If the preselected pressure is exceeded, the pressure relief valve opens so that the preselected value for the pressure in the seed storage area is reached again. The pressure relief valve closes again when the preselected value is reached. A pressure relief valve is also advantageous when fresh seed is blown into the seed storage area with air.During the period in which fresh seed is being blown into the seed storage area, the pressure relief valve can open to prevent an undesirable increase in pressure in the seed storage area. Besides or in addition to regulating the pressure in the seed storage area, the pressure relief valve can also be used to set a desired pressure in the seed discharge area and / or in the area of ​​the seed outlet(s). In the seed discharge area, the separated kernels should detach from the singulating element and fall into the seed outlet. If there is an overpressure in the housing in the seed storage area compared to the ambient air outside the housing, an air flow can develop in the seed outlet, the speed of which depends on the pressure gradient between the overpressure inside the housing and the pressure in the ambient air.The air flowing through the seed outlet can be used to accelerate the seeds detaching from the singulating element, causing them to fall into the seed furrow at a higher speed. The pressure control inside the housing with the pressure relief valve makes it possible to influence the velocity at which the singulated seeds move toward the seed furrow.

[0059] By connecting the pressure relief valve to the seed supply line, an overpressure situation in the seed storage area is avoided when the new seed is blown into the seed storage area.

[0060] Further features of the invention emerge from the claims, the figures, and the description of the figures. All features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures, can be used not only in the respective specified combination, but also in other combinations or even on their own.

[0061] The invention will now be explained in more detail using a preferred embodiment and with reference to the accompanying drawings.

[0062] They show:

[0063] Fig. 1 : a schematic sectional view of a

[0064] Seed singulating device with an almost completely closed housing,

[0065] Fig. 2: a modification of the embodiment shown in Figure 1 with an open housing,

[0066] Fig. 3: a schematic cross-sectional view of an embodiment in which the

[0067] Singling element is designed as a sowing drum,

[0068] Fig. 4: a schematic longitudinal sectional view of the device shown in Figure 3

[0069] Execution along line IV-IV in Figure 3,

[0070] Fig. 5: a schematic sectional view of a

[0071] Seed singulating device with an almost completely closed housing and a pressure relief valve, Fig. 6: a modification of the one shown in Figure 5

[0072] Seed singulating device,

[0073] Fig. 7: a schematic view of a seed singulating device in which the seed feed line has a non-return valve,

[0074] Fig. 8: a schematic sectional view of a

[0075] Seed singulating device with a differential pressure generating device arranged outside the housing, and

[0076] Fig. 9: a schematic representation of a

[0077] Differential pressure generating device connected to two seed singling devices for generating a differential pressure each.

[0078] The illustrations essentially represent specific embodiments. However, the invention is not limited to the illustrated embodiments, but can be modified by those skilled in the art to adapt it to a specific application.

[0079] Where useful, corresponding components are designated by identical reference numerals in all figures. For the sake of clarity, however, not all components that occur multiple times are always provided with reference numerals. Figure 1 shows a schematic sectional view of a seed singling device. The seed singling device has a housing 2 with a seed storage area 4 in which the seed 6 is held for singling the kernels 8. The seed storage area 4 is located in the housing 2, which also encloses the vacuum chamber 10. The vacuum chamber 10 is also located within the housing 2. In the exemplary embodiment, the vacuum chamber has a cylindrical shape. The seed storage area 4 and the vacuum chamber 10 are separated from one another by a singling element 12.In the embodiment shown in Figure 1, the singulating element 12 is designed as a seed disc 14 in which a number of seed receiving holes 16 are located. The seed disc 14 at least partly forms the rotatable vacuum chamber 10, since it forms a wall of the vacuum chamber 10 on one side. The seed receiving holes 16 can be arranged in a circle in the same disc 14. On the outer side 18 of the seed disc 14, the grains 8 of the seed 6 are positioned in the seed receiving area S for collection.

[0080] The following relationship applies to the pressure conditions within the seed singulation device:

[0081] P1 > P3 > P2 Here, pressure P1 represents the pressure at the inlet of the injection nozzle 28, pressure P2 the pressure inside the vacuum chamber 10 and pressure P3 the pressure inside the seed storage area 4. In the embodiment shown in Figure 1, the housing 2 is closed so that pressure P3 can build up in the seed storage area as an overpressure, also in relation to the pressure PO in the ambient air. The pressure conditions apply both in the case of overpressure singulation and underpressure singulation. In the case of underpressure singulation, pressure PO as the ambient pressure outside the housing 2 is in any case greater than pressure P2 in the vacuum chamber 10, whereas in the case of overpressure singulation the pressure P2 in the vacuum chamber 10 can be less than, equal to or greater than pressure PO in the ambient area outside the housing 2.

[0082] Since an overpressure P3 prevails on the outer side 18 of the sowing disc 14 in relation to the negative pressure P2 in the vacuum chamber 10, the grains 8 in the area of ​​the seed receiving holes 16 are carried along by the air flowing through them and pressed into the seed receiving holes 16 and held there by the negative pressure P2. During a rotational movement of the sowing disc 14, the grains 8 adhering to the seed receiving holes 16 are carried along in the direction of rotation, lifted out of the seed 6 and thus separated. When the pressure difference at the seed receiving holes 16 is eliminated, the grains 8 can fall into the seed outlet 26. In order to maintain the pressure P3 in the seed storage area 4 and the

[0083] To create pressure P2, the injection nozzle 28 opens into the vacuum chamber 10. In

[0084] Process air flow direction D of the process air 38 is followed by the collecting nozzle 30 with the diffuser 32. The process air 38 exiting at the end 42 of the injection nozzle 28 and the cross-sectional constriction 36 formed therein flows into the collecting nozzle 30 and is guided back out of the vacuum chamber 10 via the diffuser 32. The beginning 44 of the collecting nozzle 30 has a funnel-shaped inlet area 40 into which the end 42 of the injection nozzle 28 extends. The collecting nozzle 30 also has a cross-sectional constriction 36 which acts in the same way as the cross-sectional constriction 36 in the injection nozzle 28. In the process air flow direction D, there is at least one opening 34 between the end 42 of the injection nozzle 28 and the beginning 44 of the collecting nozzle 30, through which air 46 is sucked in from the interior of the vacuum chamber 10 along with the process air 38 and thereby conveyed out of the vacuum chamber 10.As a result, a differential pressure P3 - P2 forms between the interior of the vacuum chamber 10 and its exterior 18. The diffuser 32 creates an overpressure P3 in the housing 2 outside the vacuum chamber 10 compared to the ambient pressure PO and the pressure P2 in the vacuum chamber 10.

[0085] In the embodiment shown in Figure 1, the collecting nozzle 30 is firmly connected to the vacuum chamber 10. The injection nozzle 28 is firmly connected to the housing 2 in the embodiment shown. The vacuum chamber 10 rotates around the injection nozzle 28. The injection nozzle 28 and the collecting nozzle 30 are arranged on opposite end faces of the vacuum chamber 10. The distance between the injection nozzle 28 and the collecting nozzle 30 can be adjusted using an adjusting device. The injection nozzle 28, the collecting nozzle 30, the diffuser 32, and the opening 34 together form a differential pressure generating device 48, which sucks the air 46 out of the vacuum chamber 10 and injects it, together with the process air 38, into the seed storage area 4. To generate the air flow of the process air 38, a blower is used as the process air flow generator 50.

[0086] Figure 2 differs from the embodiment shown in Figure 1 in that the housing 2 is open at the top above the seed storage area 4. The embodiment shown here is suitable for pure vacuum singulation, since no overpressure can build up in the seed storage area 4 compared to the ambient pressure PO. Nevertheless, the pressure P2 in the vacuum chamber 10 is reduced compared to the pressure P3 in the seed storage area 4 via the differential pressure generation device 48 by sucking out the air 46 there through the opening 34.

[0087] In the embodiment shown in Figure 3, the singulating element 12 is designed as a sowing drum 20. In this embodiment, the sowing drum 20 again rotates around the injection nozzle 28. The collecting nozzle 30 with the diffuser 32 are fixedly connected to the sowing drum 20 and rotate with it. The seed receiving holes 16 are in this case formed in a ring-shaped circumferential manner in the outer surface 24 of the sowing drum casing 22 of the cylindrical vacuum chamber 10. When the sowing drum 20 rotates, it takes the grains 8 from the seed storage area 4 and conveys them into the inlet area of ​​the seed outlets 26. There, the vacuum to the seed receiving holes 16 is interrupted, so that the grains 8 fall out of the seed receiving holes 16 and reach the seed outlets 26, from where they can be conveyed into the sowing furrow. The Fig.Figure 4 shows a schematic longitudinal sectional view of the embodiment shown in Figure 3 along the line IV-IV in Figure 3, which illustrates in more detail the above-described entrainment of the grains 8.

[0088] Fig. 5, in a schematic sectional view, shows an embodiment of a seed singulating device with a nearly completely closed housing 2 and a pressure relief valve 58, which is a component of an overpressure control 54. A pressure relief valve 58 is arranged on the housing 2 for the targeted adjustment of the pressure P3 on the seed intake side and / or in the seed discharge area and / or in the area of ​​the seed outlet(s) 26(s). The overpressure control 54 measures the pressure P3 within the seed storage area 4 using a corresponding sensor. If the sensor detects that a set threshold value is exceeded, the overpressure control 54 opens the pressure relief valve 58 so that the overpressure can escape from the interior of the housing 2 according to the arrow shown in Figure 5.The pressure relief valve 58 can also be connected to the seed feed line 52 via a supply line 56 in order to support the pneumatic conveying of the grains 8 there with the air blown out via the pressure relief valve 58. The supplied seed 6 is conveyed via the seed feed line 52 into the seed storage area 4. In the illustrated embodiment, an additional process air flow generator 50 is present in the seed feed line 52 to convey the grains 8 of the seed 6 to be conveyed into the seed storage area 4. The grains 8 are fed to the seed feed line 52 via the metering device 62. If a pressure P3 in the seed storage area 4 is generated via the additional process air flow generator 50 which is above a threshold value, the overpressure control 54 can open the pressure relief valve 58 again.

[0089] Fig. 6 shows a modification of the seed singulating device shown in Figure 5. The air that conveys the grains 8 in the seed feed line 52 is not generated by an additional process air flow generator 50, but rather by the process air 38, which is blown into the seed feed line 52 via a corresponding feed line 64. To ensure that the seed storage area 4 continues to be supplied with compressed air from the differential pressure generating device 48, openings 34 are also located between the diffuser 32 and the feed line 64, through which process air can flow into the seed storage area 4 and build up an overpressure there. However, the pressure supply to the seed storage area 4 can also be provided solely via the feed line 64 / 52, which also opens into the seed storage area 4.

[0090] Fig. 7 shows a schematic view of a seed singulating device in which the seed feed line 52 has a check valve 60, here in the form of a check flap. The seed feed line 52 can be closed via the check valve 60 when no seed 6 is being conveyed through it into the seed storage area 4. The housing 2 remains almost completely closed via the check valve 60, so that when the check valve 60 is closed, the pressure P3 can build up in the seed storage area 4. When the grains 8 conveyed through the seed feed line 52 are conveyed with an air stream, the check valve 60 can pivot into the position indicated by the dashed lines. Any excess pressure in the seed storage area 4 can be compensated via the pressure relief valve 58.The check valve 60 can be designed such that it automatically moves into the closed position when no grains 8 are fed through the seed feed line 52.

[0091] A schematic sectional view of a seed singulating device 66 with a differential pressure generating device 48 in the form of a jet pump arranged outside the housing 2 is shown in Fig. 8. The process air 38 provided by the process air flow generator (not shown) flows through the injection nozzle 28, past the opening 34 to the collecting nozzle 30 with the diffuser 32. The opening 34 is connected via a suction line 70 to the interior of the vacuum chamber 10, so that the process air 38 sucks the air 46 out of the vacuum chamber 10 and there a negative pressure P2 is generated relative to the outside 18 for singulating the seed. The pressure P2 essentially also acts in the suction line 70, which connects the opening 34 to the vacuum chamber 10. The diffuser 32 is directly attached to the housing 2 in a region of the outside

[0092] 18. It is also conceivable to connect the jet pump 48, in particular the diffuser 32, to the seed singulating device 66 and the outer side 18 via a pressure line (not shown). This allows the process air 38 and the air 46 to flow to the outer side 18 and build up a pressure P3 there, in particular within the seed receiving area S. The supplied process air 38 essentially corresponds to the amount of air exiting through the seed outlet 26, i.e., the so-called shot air.

[0093] This has the advantage that essentially no additional air volume is required to generate the differential pressure and thus singulate the seed beyond the shot air, thus making the seed singulation method and device highly efficient. Furthermore, this allows for smaller cross-sections to be used for the air-carrying lines 70, thus requiring less installation space, which is particularly advantageous for large working widths.

[0094] Fig. 9 shows a schematic representation of a differential pressure generating device 48 in the form of a jet pump, which is connected to two seed singulating devices 66 for generating a differential pressure each. Via the process air flow generator 50, process air 38 is directed through the injection nozzle 28 past the opening 34 to the collecting nozzle 30 with the diffuser 32. The opening 34 is connected via suction lines 70 to two seed singulating devices 66 and their vacuum chambers 10.

[0095] As a result, air 46 is sucked out of the two vacuum chambers 10 by the differential pressure generation device 48, whereby a negative pressure P2 is generated there relative to their outer sides 18 for seed singulation. The process air 38 and the air 46 flow from the diffuser 32 through pressure lines 68 to the respective outer sides 18 of the two seed singulation devices 66, whereby a pressure P3 is generated there in each case. The pressure P3 in the outer sides 18 is in each case greater than the pressure P2 in the vacuum chambers 10, whereby a pressure difference is built up across the respective singulation elements 12 in the form of seed discs 14. The process air 38 supplied to the seed singulation devices 66 essentially corresponds to the amount of air which exits as so-called shot air together with the seed through the seed outlets 26.

[0096] List of reference symbols

[0097] Housing

[0098] Seed storage area

[0099] seeds

[0100] grains

[0101] vacuum chamber

[0102] Separation element

[0103] Seeding disc

[0104] Seed receiving holes

[0105] outside

[0106] Seeding drum

[0107] Seeding drum casing

[0108] lateral surface

[0109] Seed outlet

[0110] Injection nozzle

[0111] Collecting nozzle

[0112] diffuser

[0113] opening

[0114] Cross-sectional narrowing

[0115] Process ventilates

[0116] Entrance area 42 end

[0117] 44 Beginning

[0118] 46 Air

[0119] 48 Differential pressure generating device

[0120] 50 process air flow generators

[0121] 52 Seed supply line

[0122] 54 Overpressure control

[0123] 56 Feed

[0124] 58 Pressure relief valve

[0125] 60 check valve

[0126] 62 Dosing device

[0127] 64 supply line

[0128] 66 Seed singulating device

[0129] 68 pressure line

[0130] 70 suction line

[0131] PO pressure in the vicinity of the seed singulation device

[0132] P1 Pressure inside the injection nozzle

[0133] P2 pressure inside the vacuum chamber

[0134] P3 Pressure within the seed storage area

[0135] D Process air flow direction

[0136] S Seed intake area

Claims

Patent claims 1. A method for seed singulation by means of differential pressure for at least one seed singulation device (66), in which a singulation element (12) having seed receiving holes (16) at least co-forms a, in particular rotating, vacuum chamber (10), wherein the outer side (18) facing away from the interior of the vacuum chamber (10) receives seed (6) in a seed storage area (4) by generating an internal pressure (P2) in the vacuum chamber (10) which is lower than the external pressure on its outer side (18), which sucks the seed (6) at the seed receiving holes (16) until it is discharged into a seed outlet (26), and wherein the internal pressure (P2) in the vacuum chamber (10) of the at least one seed singulation device (66) is generated by means of a differential pressure generating device (48) in the form of at least one jet pump, 2. Method according to claim 1, characterized in that the differential pressure generating device (48) in the form of a jet pump is fluidically connected to a plurality of seed singling devices (66), in particular their vacuum chambers (10), and generates an internal pressure (P2) in the vacuum chambers (10) which is lower than the external pressure on their outside (18).

3. Method according to claim 1 or 2, characterized in that in the differential pressure generating device (48) in the form of a jet pump, process air (38) provided by a process air flow generator (50) flows through an injection nozzle (28) and is guided to a collecting nozzle (30) with a diffuser (32), wherein in the process air flow direction (D) between an end (42) of the injection nozzle (28) and a beginning (44) of the collecting nozzle (30) there is at least one opening (34) which is fluidically connected to the interior of the at least one vacuum chamber (10), so that air (46) from the vacuum chamber (10) is sucked along with the process air (38) and is thereby conveyed out of the vacuum chamber (10), so that a differential pressure (P3 - P2) is formed between the interior of the vacuum chamber (10) and its outside (18).

4. Method according to one of the preceding claims, characterized in that in the singulating element (12) having seed receiving holes (16) at least co-forms a, in particular rotating, vacuum chamber (10), wherein the outer side (18) facing away from the interior of the vacuum chamber (10) receives seed (6) in a seed storage area (4) by generating in the vacuum chamber (10) an internal pressure (P2) which is lower than the external pressure on its outer side (18), which sucks the seed (6) at the seed receiving holes (16) until it is discharged into a seed outlet (26), and wherein the internal pressure (P2) in the vacuum chamber (10) is generated by means of an injection nozzle (28) extending into the interior of the vacuum chamber (10). Process air (38) is blown in, the air flow of which is guided back out of the vacuum chamber (10) by a collecting nozzle (30) with a diffuser (32), wherein in the process air flow direction (D) there is at least one opening (34) between the end (42) of the injection nozzle (28) and the beginning (44) of the collecting nozzle (30), through which opening air (46) from the interior of the vacuum chamber (10) is sucked along with the process air (38) and thereby conveyed out of the vacuum chamber (10), so that a differential pressure (P3 - P2) is formed between the interior of the vacuum chamber (10) and its outside (18).

5. Method according to claim 4, characterized in that the diffuser (32) in the housing (2) outside the vacuum chamber (10) produces an overpressure (P3) compared to the ambient pressure (PO).

6. Method according to one of the preceding claims, characterized in that the seed storage area (4) is filled in a controlled manner via a seed supply line (52), wherein in particular the pressure (P3) in the seed receiving area (S) of the housing (2) can be additionally adjusted by means of an overpressure control (54).

7. Method according to claim 6, characterized in that the compressed air discharged from the overpressure control (54) is used through a feed (56) into the seed feed line (52).

8. Device for at least one seed singling device (66), with at least one singling element (12) having seed receiving holes (16), which at least partly forms a, in particular rotatable, vacuum chamber (10), with a seed storage area (4) on an outer side (18) facing away from the interior of the vacuum chamber (10) and with a differential pressure generating device (48), in particular with a process air flow generator (50), wherein the differential pressure generating device (48) is in the form of a jet pump and is designed such that it is fluidically connected to the interior of at least one vacuum chamber (10) of the at least one seed singling device (66) and generates an internal pressure (P2) in the vacuum chamber (10) which is lower than the external pressure on the outer side (18).

9. Device according to claim 8, characterized in that the differential pressure generating device (48) in the form of a jet pump is fluidically connected to a plurality of seed singling devices (66), in particular their vacuum chambers (10), each for generating an internal pressure (P2) which is lower than the outer sides (18) of the latter.

10. Device according to claim 8 or 9, characterized in that the vacuum chamber (10) is arranged in a housing (2) of the seed singling device (66) and / or the Differential pressure generating device (48) is arranged at least partially inside and / or outside the housing (2). B_is arranged and / or at least partially forms the housing 11. Device according to one of claims 8 to 10, characterized in that the differential pressure generating device (48), which is arranged in particular outside the housing (2), has an injection nozzle (28) connected to the process air flow generator (50) and a collecting nozzle (30) with a diffuser (32), wherein in the flow direction (D) of the process air (38) there is at least one opening (34) between an end (42) of the injection nozzle (28) and a beginning (44) of the collecting nozzle (30), which opening is fluidically connected to the interior of at least one vacuum chamber (10), in particular via a line, whereby air (46) is sucked in from the interior of the vacuum chamber (10) along with the process air (38) and is thereby conveyed out of the vacuum chamber (10), so that a differential pressure (P3 - P2) is formed between the interior of the vacuum chamber (10) and its outside (18).

12. Device according to one of claims 8 to 11, characterized in that the differential pressure generating device (48) has an injection nozzle (28) extending into the interior of the vacuum chamber (10) and connected from the outside to the process air flow generator (50) and a collecting nozzle (30) with diffuser (32), which are arranged in such a way that in the flow direction (D) of the process air (38) the end (42) of the The injection nozzle (28) and the beginning (44) of the collecting nozzle (30) are located facing each other in the interior of the vacuum chamber (10), wherein between the end (42) of the injection nozzle (28) and the beginning (44) of the collecting nozzle (30) there is at least one opening (34) through which air (46) is sucked in from the interior of the vacuum chamber (10) together with the process air (38) and is thereby conveyed out of the vacuum chamber (10), so that a differential pressure (P3 - P2) is formed between the interior of the vacuum chamber (10) and its outside (18).

13. Device according to one of claims 8 to 12, characterized in that the distance between the injection nozzle (28) and the collecting nozzle (30) is adjustable with an adjusting device.

14. Device according to one of claims 8 to 13, characterized in that the singling element (12) is designed as a sowing disc (14) and / or a sowing drum casing (22) and is a replaceable part of the vacuum chamber (10).

15. Device according to one of claims 8 to 14, characterized in that a seed supply line (52) in the seed storage area (4) of the housing (2), wherein in particular the seed supply line (52) is a check valve (60).

16. Device according to one of claims 8 to 15, characterized in that a pressure relief valve (58) is arranged on the housing (2) for the targeted adjustment of the pressure (P3) on the seed intake side and / or in the seed discharge area and / or in the area of the seed outlet(s) (26) / - outlets (26), wherein in particular the Pressure relief valve (58) is connected to the seed supply line (52).

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