DE102024120929A1 - Method and device for seed singulation by means of differential pressure - Google Patents

Abstract

The present invention relates to a method and a device for seed singulation by means of differential pressure. By blowing the process air (38) successively through an injection nozzle (28) and a collecting nozzle (30) into a diffuser (32) opening into the seed storage area (4), with an opening (34) to the vacuum chamber (10) being present between the injection nozzle (28) and the collecting nozzle (30), through which air (46) from the vacuum chamber (10) is sucked into the air flow of the process air (38), a particularly powerful and energy-efficient system is created for generating a differential pressure (P3 - P2) that can be used for seed singulation.

Description

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

The publication US 6,142,086 describes a device for seed singulation with a rotating drum, on the inside of which a negative pressure is generated and which has a number of holes on its outer casing. The negative pressure acting in the area of the holes causes seeds to adhere to the drum in a seed storage area adjacent to the drum. In this system, a blower generates an overpressure that is present in the seed storage area on the outside of the drum, and at the same time air is sucked out of the inside of the drum via a vacuum line that opens into the interior of the drum, so that a negative pressure is created there. If a negative pressure is generated inside the drum in this way, considerable volumes of air must be moved, which is associated with a corresponding amount of effort. The pressure equalization between the positive pressure and negative pressure sides of the drum also results in considerable losses of process air, which require oversized blowers and increased energy consumption for the actual process.

From the Scripture US 4,915,258 A device for separating seeds is also known. A first chamber, which is subjected to a negative pressure, is covered by a rotating, driven disk, on the surface of which there are a number of holes. A seed storage area is formed in a second chamber, which is located on the opposite side of the disk. The seeds held there only adhere to the holes in the disk due to the vacuum in the chamber, because no special pressure is built up in the seed storage area by an air supply fan. This means that a separate pressure fan is not required, but when the seeds are released into the downpipe there is no air flow to support the removal of the respective seeds. In order to ensure that the seeds adhere reliably to the disk, a considerable negative pressure must be generated on the side of the disk facing away from the seed storage area.

The writing DE 2 401 306 A1 discloses a rotating wheel for seed singulation with a number of tubes extending in a radial direction, in which a negative pressure is generated by an air stream guided past the inner ends by means of a Bernoulli effect in order to suck in a grain at each of the outer ends of the tubes and take it away from a grain supply. There is no pressure chamber.

Overall, the devices known from the state of the art require a considerable amount of effort to generate a sufficient negative pressure in the vacuum chamber for reliable grain separation. 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 pollution of the environment through moving dust particles and/or particles of pesticides with which the seed may be mixed.

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.

The object is achieved for a seed singling method with the features of claim 1 and for a device for seed singling with the features of claim 8.

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 outside facing away from the interior of 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 its outside, 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 singulation device is generated by means of a differential pressure generating device in the form of at least one jet pump.

The differential pressure acts on the singling element, which enables 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 be pulsated exchange, another medium, for example air in a vacuum chamber, can be sucked in, accelerated and compressed or conveyed. The differential pressure generating device in the form of the jet pump can be connected via a suction line to a vacuum chamber and/or a pressure line or the diffuser to an outside in order to generate a pressure difference via a separating element.

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 small compared to previously known systems. The Bernoulli effect can be used to increase the volume of process air along the flow path with additional air. The process air is sucked out of the vacuum chamber. By sucking the additional volume of air in addition to the process air out of the vacuum chamber, the exhaust air sucked out there using the Bernoulli effect creates a vacuum. The vacuum is created exactly where it is needed for seed singulation. The air flowing from the seed storage area into the vacuum chamber via the seed receiving holes, for example, is sucked directly back into the process air as recirculated air and 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, which, if desired, creates a pressure increase precisely there. The process air supplied essentially corresponds to the air or shot air exiting through an outlet opening of the singling device together with the singulated seed. Due to this multiple increase in efficiency, namely at several points in the air system of a seed singling device, it is possible to make the blowers smaller and reduce the drive power required for this. The cross-sections of the hoses for the air supply, i.e. the pressure lines, can be chosen to be smaller and thus more cost-effective. The inventive design of the method and device for seed singling creates a comparatively high differential pressure with a comparatively low operating effort when the seed receiving holes are essentially closed off by seed, which can be used effectively 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.

The increased efficiency of the air system means that the seed singulation system can operate with a lower air throughput volume. This reduces the flow speed of the circulating air drawn in from the area around the seed drill, and also reduces the risk of dirt particles floating in the circulating air being sucked into the components of the seed singulation system, which can impair the quality of the seed singulation. The air system can be used for all types of seed.

Preferably, the differential pressure generating device in the form of a jet pump is fluidically connected to several seed singling 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 outside. A jet pump or differential pressure generating device can be connected to one or more seed singling devices via one or more suction lines and/or pressure lines. At least one negative pressure can be generated in, in particular at least one vacuum chamber via the suction line. This makes it possible to singulate the seed.

In a further preferred embodiment of the method, in the differential pressure generating device in the form of a jet pump, process air provided by a process air flow generator flows through an injection nozzle and is guided to a collecting nozzle with a diffuser. In the process air flow direction, there is at least one opening between one end of the injection nozzle and one beginning of the collecting nozzle, which is fluidically connected to the interior of the at least one vacuum chamber. Air from the vacuum chamber is thus sucked in with the process air and thereby transported out of the vacuum chamber. This allows a differential pressure to form between the interior of the vacuum chamber and its outside.

A differential pressure is generated for the method for seed singulation. The differential pressure acts on seed receiving holes that are formed on a singulation element. The singulation element at least co-forms a low-pressure area through a, in particular rotating, vacuum chamber, for example by forming a side wall of the vacuum chamber. The outside of the singulation element facing away from the interior of the vacuum chamber receives seed in a seed storage area during a rotating movement by generating an internal pressure in the vacuum chamber that is lower than the external pressure on its outside, via which the seeds in the seed storage area are The grains held in the storage area are sucked into the seed receiving holes. The seed receiving holes have a shape and size that is suitable for the grains to be separated, so that a single grain is sucked into and held at a seed receiving hole, but cannot be sucked through the seed receiving hole. The grains adhering to the seed receiving holes are carried along in the direction of rotation during the rotating movement of the singling element until they reach a delivery point and are released from there into a seed outlet.

The internal pressure in the vacuum chamber, which is lower than the external pressure, is generated by blowing in process air via an injection nozzle extending into the interior of the vacuum chamber, the air flow of which is then guided out of the vacuum chamber by a collecting nozzle with a diffuser, with at least one opening in the direction of the process air flow between the end of the injection nozzle and the beginning of the collecting nozzle, through which air is sucked in with the process air from the interior of the vacuum chamber in the manner of a jet pump and is thereby 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 pressed 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 at another location on a sowing machine equipped with the seed singulation according to the invention. However, several process air flow generators can also be provided, for example one side channel compressor per row of the sowing machine 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 in front of the outlet opening in the direction of flow of the process air in order to influence the flow of the process air as it passes between the closed space inside the injection nozzle and the free space behind the outlet opening of the injection nozzle in the direction of flow of the process air. At the narrowest point of the injection nozzle, the dynamic pressure or the back pressure is maximum and the hydrostatic pressure is 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 speed and a 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 in and carried along into the air flowing out of the injection nozzle through the opening located between the end of the injection nozzle and the beginning of the collecting nozzle, like a Venturi nozzle. The air sucked out of the vacuum chamber reduces the internal pressure in the vacuum chamber, so that a differential pressure is created between the inside of the vacuum chamber and its outside.

To ensure that the air flow of the process air flowing over the injection nozzle does not remain in the vacuum chamber and thereby equalizes the differential pressure again, the air flow is directed back out of the vacuum chamber behind the opening by the collecting nozzle with diffuser 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 as seen 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 reduced. 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 maximum and the hydrostatic pressure in the collecting nozzle is minimum. Here too, the speed of the process air flowing through the injection nozzle increases in proportion to the cross-sections when flowing into the narrower part in the direction of flow, because according to the law of continuity, the same mass flows through the entire pipe per unit time. In this way, the air flow of the process air enriched with the air sucked in from the vacuum chamber is guided out of the vacuum chamber via the collecting nozzle and the reduced internal pressure in the vacuum chamber is maintained.

The flow velocity of the process air in this flow section is slowed down again via the diffuser and the hydrostatic pressure in the process air is increased again, so that the kinetic energy present in the process air is converted into pressure energy. The deceleration of the flow is achieved by a continuous or discontinuous expansion of the flow cross-section in the flow direction of the process air by the diffuser. The diffuser can be connected directly to the cross-sectional constriction of the collecting nozzle, which results in 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.

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.

At the beginning of singulation, a slightly higher initial inlet pressure must be provided, as more air flows back into the vacuum chamber through seed intake holes that are not yet closed. However, with closed holes the pressure requirement drops and the process air output required in stationary operation is low.

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 side of the singulation element that receives the seed. An increased pressure in the seed storage area can be easily maintained if the device for seed singulation is surrounded by an at least essentially 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 the 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 or a sowing tube or a discharge line. The housing can also be open or pressure-sealed.

The pressure conditions in the seed singulation system can be easily adjusted and coordinated by appropriate design and 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 sucked out of the vacuum chamber. The opening can be designed in particular in the form of an annular gap in order to make 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 to one another. The opening can be formed by holes in the transition area. The design and dimensioning of the blower used to supply the process air to the injection nozzle also has an influence on the pressure conditions in the seed singulation system.

The pressure of the process air that is fed to the injection nozzle and the delivery volume of the blower can optionally be designed to be variable in order to influence the differential pressure during seed singulation and the amount of air used for seed singulation. The influencing factors that affect the respective pressures within the seed singulation can be adjustable or variable, such as the corresponding line cross-sections, cross-section constrictions, distances between the components, and the like. The components of the seed singulation can be designed and adjusted in such a way that a high pressure difference is achieved in the seed singulation. However, optimization can also be aimed at the smallest possible amount of air flowing out of the seed singulation. High shot speeds of the grains are not always helpful when depositing them. The shot speeds of the grains can be reduced by a lower overpressure or even just an atmospheric pressure in the seed storage area. With a lower pressure in the seed storage area, the effort required to seal the housing surrounding the seed singulation can also be lower. Due to the variability of the singulation pressure, the system for seed singulation according to the invention can be used in various seed drills, for example in seed drills that have a catch roller in the seed deposit area in the soil, as well as in seed drills that do not have a catch roller in the deposit area.

The higher efficiency of the air system can be used to select smaller dimensions for the injection nozzle, the collecting nozzle and the diffuser. This also makes it possible to reduce the singulation element and thus the size of the sowing unit as a whole.

By blowing the process air successively through an injection nozzle and a collecting nozzle into a diffuser that opens into the seed storage area, with an opening between the injection nozzle and the collecting nozzle leading to the vacuum chamber through which air from the vacuum chamber is sucked into the air flow of the process air, a particularly powerful and energy-efficient system is created for generating a differential pressure that can be used for grain separation. 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 that is sucked out of the vacuum chamber. By sucking the additional air volume in addition to the process air straight out of the vacuum chamber, the exhaust air sucked out there using the Bernoulli effect creates a vacuum exactly where it is needed for seed separation. The air flowing from the seed storage area via the seed receiving holes into the vacuum chamber, for example, is sucked back into the process air as circulating air and transported back 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, which, if desired, creates an increase in pressure precisely there. 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 blowers smaller and reduce the drive power required for this. The cross-sections of the hoses for the air supply, i.e. the pressure lines, can be chosen to be smaller and thus more cost-effective. The inventive design of the method and the device for seed singulation creates a comparatively high differential pressure with comparatively low operating expenditure when the seed receiving holes are essentially closed off by seed, which can be used effectively 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.

The increased efficiency of the air system means that the seed singulation system can operate with a lower air throughput volume. This reduces the flow speed of the circulating air drawn in from the area around the seed drill, and also reduces the risk of dirt particles floating in the circulating air being sucked into the components of the seed singulation system, which can impair the quality of the seed singulation. The air system can be used for all types of seed.

The device according to the invention for at least one seed singling device has at least one singling element having seed receiving holes, which at least forms a vacuum chamber, in particular a rotatable one. The device has a seed storage area on an outside of the singling element facing away from the interior of the vacuum chamber. The device also has 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 designed in such a way that it is fluidically 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 a pressure difference required for seed singling across the singling element in an efficient and space-saving manner.

In a preferred embodiment, the differential pressure generating device in the form of a jet pump is fluidically connected to several seed singling devices, in particular their vacuum chambers, each for generating an internal pressure that is lower than that on their outside. This enables efficient generation of a pressure difference for seed singling in a plurality of seed singling devices. In this case, several seed singling devices can be connected in groups to a differential pressure generating device in the form of a jet pump.

Preferably, the vacuum chamber is arranged in a housing of the seed singling 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 singling device and can be 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 singling device and/or the housing. For example, the diffuser can be connected directly to the housing, whereby lines, in particular a pressure line to the housing, saved and existing installation space can be used optimally.

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 one end of the injection nozzle and one 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 in along with the process air and is thereby transported out of the vacuum chamber. A differential pressure is thus formed between the interior of the vacuum chamber and its outside. The opening can be connected to the vacuum chamber via a suction line, for example. The differential pressure generated acts via the singling element, whereby the seed can be singulated.

At least one singling element is used for the device, which has seed receiving holes and which at least forms a, in particular rotatable, vacuum chamber. The device has a seed storage area on an outside of the singling element facing away from the interior of the vacuum chamber. The device also has a differential pressure generating device with a process air flow generator, wherein the differential pressure generating device has an injection nozzle extending into the interior of the vacuum chamber and connected from the outside to the process air flow generator, and a collecting nozzle with a diffuser. The injection nozzle and the collecting nozzle with diffuser are arranged in such a way that, in the flow direction 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 between the end of the injection nozzle and the beginning of the collecting nozzle through which air from the inside of the vacuum chamber is sucked in with the process air and thereby transported out of the vacuum chamber, so that a differential pressure is formed between the inside of the vacuum chamber and its outside. 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 outside. The opening can be connected via a suction line to the inside of at least one vacuum chamber.

The vacuum chamber can be designed in a housing, in particular a rotating one. In the housing, the seed singulation is protected against disruptive influences from outside. The housing creates defined conditions in which trouble-free operation is possible. The housing can be open or almost completely closed. The design of the housing allows the device to be operated both as a positive pressure and negative pressure singulation, whereby the differential pressure can remain constant.

According to one embodiment of the invention, the diffuser in the housing outside the vacuum chamber applies an excess pressure compared to the ambient pressure. In particular, in a nearly sealed housing, the pressure prevailing therein can be increased by the process air blown out by the diffuser.

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 guides 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 ensures that the air flowing in from the vacuum chamber is well integrated into the air flow of the process air. Since the inflowing air is guided along the 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 cross flows in the merging area are thus largely avoided. The funnel shape also results in a flow path along the length of which the air flows to be merged can mix with one another. The air supplied from the vacuum chamber can therefore be integrated into the process air flow without major performance losses.

The collecting nozzle can be firmly connected to the vacuum chamber. For a high differential pressure, it is desirable to generate as high a negative pressure as possible in the vacuum chamber. If the collecting nozzle were not firmly connected to the vacuum chamber, air from outside, in particular 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 that can be achieved with the device with otherwise identical components would thus be smaller and the efficiency of the separation system would also be reduced. worse. In order to prevent air from flowing in 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 was not permanent. This would result in increased construction and assembly costs and increased wear could occur in this area. This can be avoided if the collecting nozzle is permanently connected to the vacuum chamber. The permanent connection can be designed to be gas-tight, for example by means of closed walls, abutment surfaces and edges in the transition area. 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, thereby avoiding joints that are not gas-tight. Several molded parts can also be connected to one another in a gas-tight manner in the respective abutment area, for example by means of gas-tight seals between the components, a gas-tight adhesive connection or a gas-tight filler such as silicone or acrylic, which is applied to joints in the abutment area of the components after they have been assembled. With fixed connections between components, gas-tight connections are considerably easier to implement than with connections that allow relative movement between components.

The vacuum chamber can be designed in a cylindrical shape. The cylindrical shape results in uniform flow conditions inside the vacuum chamber, a constant circumferential shape when the vacuum chamber rotates, and easy installation in the shape of a housing. The bearing of a cylindrical component is also inexpensive and simple. With this basic shape, the axis of rotation can correspond to the main axis of inertia, which prevents imbalances and increased wear on the bearings and drives.

The injection nozzle and the collecting nozzle can be arranged on the opposite ends of the vacuum chamber. Both components can thus be mounted individually, for example one of the components is connected to the vacuum chamber in a rotationally fixed manner and the other component is connected to a pivot bearing. Such an arrangement also makes it possible to design the area of the opening without struts, supports, webs and the like that would disrupt the air flow.

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.

According to one embodiment of the invention, the distance between the injection nozzle and the collecting nozzle can be adjusted using an adjustment device. By changing the distance between the injection nozzle and the collecting nozzle, the negative pressure in the negative pressure 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 be placed on the side of the sowing disc in the seed singling area and can easily be taken along with the seed receiving holes. There is still enough space over the radius of the sowing disc for the diffuser through which the process air can flow into the seed storage area. The collecting nozzle with the diffuser can be firmly connected to the sowing disc and can also be exchanged with it. In the direction of rotation of the sowing disc, the grains taken along can be released from the seed receiving holes in an area away from the seed singling area and delivered to a seed outlet.

The singling element can be designed as a sowing drum and have the seed receiving holes in the outer surface of the cylindrical vacuum chamber. Several rings of seed receiving holes can be formed next to each other on the outer surface across the width of the sowing drum. If the singling element is cylindrical and the seed receiving holes in the individual rings are the same distance apart, several seed outlets can be fed with singled seeds evenly and in the same working cycle using a singling device.

According to one embodiment of the invention, the singling element is designed as a seeding disc and/or a seeding drum casing and is a replaceable part of the vacuum chamber. With a replaceable seeding disc and/or a replaceable seeding drum casing, the seed singling device can be adapted to different seeds by simply exchanging these components. Depending on the type of seed disc or seed drum casing, the seed receiving holes may be of different sizes and have a different geometry, they may be in a different position, the number of seed receiving holes may differ and/or the length and/or shape of the injection nozzle and/or the collecting nozzle and/or the diffuser may vary.

The seed storage area can be formed in a housing that encloses the vacuum chamber. The housing provides a defined spatial arrangement of the components to one another. The interior of the housing is protected against external disruptive 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 excess pressure in the housing can be used to shoot the isolated grains into the seed outlet with the outflowing compressed air.

The injection nozzle can be permanently connected to the housing. By permanently mounting the injection nozzle on the housing, the injection nozzle can be connected to a process air flow generator using a simple hose. The permanent mounting of the injection nozzle on the housing can easily be made gas-tight. The outer casing of the seed singulation device is robust and insensitive to external influences.

The vacuum chamber can rotate around the injection nozzle. The injection nozzle practically forms a shaft on which the vacuum chamber rotates. This arrangement results in defined geometric conditions 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.

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 separating element. If the seed supply is too low, it is possible that individual seed receiving holes are not filled with seeds, which leads to gaps in the seed row that has been deposited. But a level that is too high is also disadvantageous because it can hinder the separation of individual seeds. With controlled filling, as much seed as is required for reliable functioning of the seed separation can be fed in continuously or in cycles. This can preferably be done with a conveying air flow. Suitable sensors such as a light barrier, ultrasonic or capacitive sensors can be used to measure the level of the seed supply. Driven slides, cell wheels and the like can be used to open and close the feeder.

The pressure in the seed intake area of the housing can be additionally adjustable using an overpressure control. An overpressure situation with too high a hydrostatic pressure in the seed storage area can be avoided using an overpressure control, for example using a pressure relief valve. If the hydrostatic pressure in the seed storage area exceeds a threshold value, the pressure relief valve opens. The pressure relief valve can be adjustable to different threshold values.

According to one embodiment of the invention, the compressed air discharged from the overpressure control is used by feeding it back into the seed feed line. In this way, the excess compressed air is still used to transport the seed.

According to one embodiment of the invention, a seed feed line opens into the seed storage area of the housing, whereby the seed feed line in particular has a non-return valve. New seed can be fed into the seed storage area via the seed feed line in order to replace seed that has been separated and deposited in the soil. The feed can be continuous, timed, controlled by sensors or in response to a respective operating signal.

The check valve allows seed to be fed into the seed storage area, but pressure losses in the seed storage area via the seed supply line are avoided if no seed is fed to the seed storage area for a time.

According to one embodiment of the invention, a pressure relief valve is provided 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) arranged, wherein in particular 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 blown into the seed storage area, the pressure relief valve can open in order to avoid 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 delivery area and/or in the area of the seed outlet(s). In the seed delivery area, the separated grains should detach from the singling 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 occur 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 grains detaching from the singling element so that they fall into the sowing furrow at an increased speed. By regulating the pressure inside the housing with the pressure relief valve, it is thus possible to influence the shot speed at which the separated grains move in the direction of the sowing furrow.

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.

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 combination specified in each case, but also in other combinations or on their own.

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

• 1: eine schematische Schnittansicht einer Saatgutvereinzelungsvorrichtung mit einem nahezu vollständig geschlossenen Gehäuse,
• 2: eine Abwandlung der in 1 gezeigten Ausführung mit einem offenen Gehäuse,
• 3: eine schematische Querschnittansicht einer Ausführung, in der das Vereinzelungselement als Sätrommel ausgebildet ist,
• 4: eine schematische Längsschnittansicht der in 3 gezeigten Ausführung entlang der Linie IV-IV in 3,
• 5: eine schematische Schnittansicht einer Saatgutvereinzelungsvorrichtung mit einem nahezu vollständig geschlossenen Gehäuse und einem Druckbegrenzungsventil,
• 6: eine Abwandlung der in 5 gezeigten Saatgutvereinzelungsvorrichtung,
• 7: eine schematische Ansicht einer Saatgutvereinzelungsvorrichtung, bei der die Saatgutzuleitung eine Rückschlagklappe aufweist,
• 8: eine schematische Schnittansicht einer Saatgutvereinzelungsvorrichtung mit einer außerhalb des Gehäuses angeordneten Differenzdruckerzeugungseinrichtung, und
• 9: eine schematische Darstellung einer Differenzdruckerzeugungseinrichtung, die mit zwei Saatgutvereinzelungsvorrichtungen zur Erzeugung jeweils eines Differenzdruckes verbunden ist.

They show:

• 1 : a schematic sectional view of a seed singulating device with an almost completely closed housing,
• 2 : a variation of the 1 shown version with an open housing,
• 3 : a schematic cross-sectional view of an embodiment in which the singling element is designed as a sowing drum,
• 4 : a schematic longitudinal sectional view of the 3 shown version along the line IV-IV in 3 ,
• 5 : a schematic sectional view of a seed singulating device with an almost completely closed housing and a pressure relief valve,
• 6 : a variation of the 5 shown seed singulation device,
• 7 : a schematic view of a seed singulating device in which the seed supply line has a non-return valve,
• 8 : a schematic sectional view of a seed singulating device with a differential pressure generating device arranged outside the housing, and
• 9 : a schematic representation of a differential pressure generating device which is connected to two seed singulating devices for generating a differential pressure each.

The illustrations essentially represent concrete embodiments. The invention is not limited to the embodiments shown, but can be modified in a skilled manner in order to adapt it to a specific application.

Where appropriate, corresponding components are designated with identical reference numbers in all figures. However, for reasons of clarity, if components occur more than once, not all of them are always provided with reference numbers.

In 1 a schematic sectional view of a seed singling device is shown. The seed singling device has a housing 2 with a seed storage area 4 in which the seed 6 is kept for singling the grains 8. The seed storage area 4 is located is 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 separating element 12. In the 1 In the embodiment shown, the singling element 12 is designed as a sowing disk 14 in which there are a number of seed receiving holes 16. The sowing disk 14 at least 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 disk 14. The grains 8 of the seed 6 are available for collection in the seed receiving area S on the outside 18 of the sowing disk 14.

The following ratio applies to the pressure conditions within the seed singulation device: $$\text{P1}>\text{P3}>\text{P2}$$

The pressure P1 represents the pressure at the inlet of the injection nozzle 28, the pressure P2 represents the pressure within the vacuum chamber 10 and the pressure P3 represents the pressure within the seed storage area 4. 1 In the embodiment shown, the housing 2 is designed to be closed, so that the pressure P3 can build up in the seed storage area as an overpressure in relation to the pressure P0 in the ambient air. The pressure conditions apply both in the case of overpressure singulation and underpressure singulation. In the case of underpressure singulation, the pressure P0 as the ambient pressure outside the housing 2 is in any case greater than the pressure P2 in the underpressure chamber 10, while the pressure P2 in the underpressure chamber 10 in the case of overpressure singulation can be less than, equal to or greater than the pressure P0 in the ambient area outside the housing 2.

Since there is an overpressure P3 on the outside 18 of the sowing disk 14 in relation to the negative pressure P2 in the negative pressure 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. When the sowing disk 14 rotates, 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 create the pressure P3 in the seed storage area 4 and the pressure P2 in the vacuum chamber 10, the injection nozzle 28 opens into the vacuum chamber 10. In the process air flow direction D of the process air 38, the collecting nozzle 30 with the diffuser 32 is connected. 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 out of the vacuum chamber 10 again 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, 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 inside of the vacuum chamber 10 with the process air 38 and thereby conveyed out of the vacuum chamber 10. This creates a differential pressure P3 - P2 between the inside of the vacuum chamber 10 and its outside 18. The diffuser 32 creates an overpressure P3 in the housing 2 outside the vacuum chamber 10 compared to the ambient pressure P0 and the pressure P2 in the vacuum chamber 10.

In the 1 In the embodiment shown, 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 the 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 blows it into the seed storage area 4 together with the process air 38. In order to generate the air flow of the process air 38, a blower is used as a process air flow generator 50.

The 2 differs from that in the 1 shown embodiment in that the housing 2 is open on the top above the seed storage area 4. The embodiment shown here is suitable for pure vacuum singulation, since no overpressure can be built up in the seed storage area 4 compared to the pressure P0 in the environment. Nevertheless, the pressure P2 in the vacuum chamber 10 is increased compared to the pressure P3 in the seed storage area via the differential pressure generating device 48. 4 by sucking out the air 46 through the opening 34.

In the 3 In the embodiment shown, the singling element 12 is designed as a sowing drum 20. In this embodiment, the sowing drum 20 rotates again around the injection nozzle 28. The collecting nozzle 30 with the diffuser 32 are firmly connected to the sowing drum 20 and rotate with it. The seed receiving holes 16 are in this case formed in a ring-shaped manner in the outer surface 24 of the sowing drum shell 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 negative pressure 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 and can be conveyed from there into the sowing furrow. The 4 shows a schematic longitudinal sectional view of the 3 shown version along the line IV-IV in 3 , which further illustrates the entrainment of the grains 8 described above.

The 5 in a schematic sectional view shows an embodiment of a seed singling device with an almost completely closed housing 2 and a pressure relief valve 58, which is part of an overpressure control 54. A pressure relief valve 58 is arranged on the housing 2 for the targeted setting 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 or the seed outlets 26. The overpressure control 54 measures the pressure P3 within the seed storage area 4 with a corresponding sensor. If the sensor detects that a set threshold value has been exceeded, the overpressure control 54 opens the pressure relief valve 58 so that the overpressure is adjusted according to the 5 can escape from the interior of the housing 2 via the arrow shown. The pressure relief valve 58 can also be connected to the seed feed line 52 via a feed line 56 in order to support the pneumatic conveying of the grains 8 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 embodiment shown, an additional process air flow generator 50 is present in the seed feed line 52 in order to convey the grains 8 of the seed 6 to be fed 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 is generated in the seed storage area 4 via the additional process air flow generator 50 that is above a threshold value, the overpressure control 54 can open the pressure relief valve 58 again.

The 6 shows a modification of the 5 shown seed singling device. The air that transports the grains 8 in the seed feed line 52 is not generated by an additional process air flow generator 50, but with the process air 38, which is blown into the seed feed line 52 via a corresponding feed line 64. So that the seed storage area 4 continues to be supplied with compressed air from the differential pressure generating device 48, there are also openings 34 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. The pressure supply to the seed storage area 4 can also be carried out solely via the feed line 64/52, which also opens into the seed storage area 4.

The 7 shows a schematic view of a seed singling 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 if 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 be built up in the seed storage area 4. If the grains 8 conveyed through the seed feed line 52 are conveyed with an air stream, the check valve 60 can swing open into the position indicated in dashed lines. Any excess pressure in the seed storage area 4 can be compensated for 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.

A schematic sectional view of a seed singling device 66 with a differential pressure generating device 48 in the form of a jet pump arranged outside the housing 2 is shown in 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 to the interior of the vacuum chamber 10 via a suction line 70, so that the air 46 is sucked out of the vacuum chamber 10 by the process air 38 and a negative pressure P2 is generated there with respect to the outside 18 for the separation of seeds. The pressure P2 also acts essentially in the Suction line 70, which connects the opening 34 with the vacuum chamber 10.

The diffuser 32 is arranged directly on the housing 2 in an area of the outer side 18. It is also conceivable to connect the jet pump 48, in particular the diffuser 32, to the seed singling 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 process air 38 supplied essentially corresponds to the amount of air that exits through the seed outlet 26, i.e. the so-called shot air.

This has the advantage that essentially no additional air volume is required to generate the differential pressure and thus to separate the seed beyond the shot air, which means that the method and device for separating the seed are highly efficient. In addition, this enables smaller line cross-sections to be used for the air-carrying lines 70, which means that less installation space is required, which is particularly advantageous with large working widths.

In 9 is a schematic representation of a differential pressure generating device 48 in the form of a jet pump, which is connected to two seed singling devices 66 for generating a differential pressure. Process air 38 is guided via the process air flow generator 50 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 singling devices 66 or their vacuum chambers 10.

As a result, air 46 is sucked out of the two vacuum chambers 10 by the differential pressure generating device 48, whereby a vacuum P2 is generated there in relation 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 disks 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.

list of reference symbols

2

Housing

4

seed storage area

6

seeds

8

grains

10

vacuum chamber

12

separation element

14

sowing disc

16

seed holes

18

outside

20

seeding drum

22

seed drum casing

24

lateral surface

26

seed outlet

28

injection nozzle

30

collecting nozzle

32

diffuser

34

opening

36

narrowing of the cross-section

38

process air

40

entrance area

42

End

44

Beginning

46

Air

48

differential pressure generating device

50

process air flow generator

52

seed supply line

54

overpressure control

56

feeding

58

pressure relief valve

60

check valve

62

dosing device

64

supply line

66

seed singulation device

68

pressure line

70

suction line

P0

Pressure in the vicinity of the seed singulation device

P1

pressure inside the injection nozzle

P2

pressure inside the vacuum chamber

P3

pressure within the seed storage area

D

process air flow direction

S

seed intake area

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• US 6,142,086 [0002]
• US 4,915,258 [0003]
• DE 2 401 306 A1 [0004]

Claims (16)

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, procedure 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). procedure 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 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). Method according to one of the preceding claims, characterized in that a separating 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) is generated by blowing in process air (38) via an injection nozzle (28) extending into the interior of the vacuum chamber (10), the air flow of which is collected by a collecting nozzle (30) with a diffuser (32) is led out of the vacuum chamber (10) again, 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 air (46) is sucked in from the interior of the vacuum chamber (10) together 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). procedure 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 (P0). 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). procedure 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). Device for at least one seed singling device (66), with at least one singling element (12) having seed receiving holes (16), which at least co-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 outside (18). device according to claim 8 , characterized in that the differential pressure generator The supply 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 that on their outer sides (18). device according to claim 8 or 9 , characterized in that the vacuum chamber (10) is arranged in a housing (2) of the seed singulating 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 Device according to one of the Claims 8 until 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 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) 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). Device according to one of the Claims 8 until 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 a 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 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) with the process air (38) and is thereby conveyed out of the vacuum chamber (10), so that between the interior of the vacuum chamber (10) and on the outside (18) of which a differential pressure (P3 - P2) is formed. Device according to one of the Claims 8 until 12 , characterized in that the distance between the injection nozzle (28) and the collecting nozzle (30) is adjustable by means of an adjusting device. Device according to one of the Claims 8 until 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). Device according to one of the Claims 8 until 14 , characterized in that a seed supply line (52) opens into the seed storage area (4) of the housing (2), wherein in particular the seed supply line (52) has a check valve (60). Device according to one of the Claims 8 until 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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