Material distribution system for a spreading machine, spreading machine and method for distributing spreading material

Abstract

A material distribution system (12) for an agricultural spreading machine (10) is disclosed, with a main distribution unit (20) for generating a plurality of conveying air streams (50) charged with spreading material (48), a plurality of dosing systems (28) which are each configured to be operated pneumatically by means of a dosing air stream (52) and to dose the spreading material (48) conveyed into the dosing system (28) via one of the conveying air streams (50), and with one or more blowers (36, 40), which are configured to generate the conveying air having a conveying air pressure (pF) for the conveying air streams (50) and to generate the dosing air having a dosing air pressure (pD) for the dosing air streams (52).

Description

[0001]Material distribution system for a spreading machine, spreading machine and method for distributing spreading material Description The invention relates to a material distribution system according to the preamble of patent claim 1, a spreading machine according to the preamble of patent claim 10 and a method for distributing spreading material according to the preamble of patent claim 11. Material distribution systems of modern agricultural spreading machines can be designed as so-called nursing systems, in which a main distribution unit is used to generate several conveying air flows loaded with spreading material. The conveying air flows are then fed to several material receiving units of the spreading machine, wherein the material receiving units can each be assigned to a dosing system or be part of a dosing system.The application material received via the material receiving units is then dosed in dosing systems so that the dosed application material can be deposited onto the agricultural field via depositing devices. The dosing systems can be operated pneumatically with a dosing air flow. Corresponding material distribution systems typically have one or more blowers to provide the conveying air for the conveying air flows and the dosing air for the dosing air flows. The conveying air pressure of the conveying air flows and the dosing air pressure of the dosing air flows typically differ from one another during operation of the material distribution system. It is known from document EP 3 987 904 A1 that the appropriate pressure differences between the conveying air pressure and the dosing air pressure depend on the type of material being distributed.Consequently, it is advantageous to generate conveying air flows and dosing air flows in which the conveying air pressure and the dosing air pressure have a constant pressure difference specific to the material being distributed. P22-047 However, maintaining a constant pressure difference specific to the material being distributed between the conveying air pressure and the dosing air pressure leads to problems in some operating situations of the material distribution system. In this context, for example, the emptying of a storage container for the application material or the emptying of the dosing systems can be mentioned. In both situations, maintaining a predetermined pressure difference between the conveying air pressure and the dosing air pressure can lead to a blockage in the dosing systems, which can impair or even interrupt the dosing process. The object underlying the invention is therefore to enable needs-based adaptation of the air pressure control in pneumatic material distribution systems.The object is achieved by a material distribution system of the type mentioned above, wherein the material distribution system according to the invention has a control device configured to adjust the conveying air pressure during a discharge process in several different operating modes of the material distribution system in a mode-specific manner depending on the metering air pressure. The control device is preferably configured to adjust the conveying air pressure during the discharge process in the respective operating modes of the material distribution system in such a way that a predetermined mode-specific pressure difference to the metering air pressure is maintained in the respective operating modes. The mode-specific pressure differences maintained in the respective operating modes differ from one another.For example, the control device can be configured to set a first pressure difference between the conveying air pressure and the metering air pressure in a first operating situation during the application process and to set a second pressure difference between the conveying air pressure and the metering air pressure in a second operating situation during the application process. The metering air pressure serves as a reference variable in each of the multiple operating modes. The metering air pressure can change for various reasons P22-047 during the application process, for example because energy is to be saved, because temporary changes in the application material are detected, or because the metering systems of the material distribution system need to be emptied. The metering air pressure can be specified by operator inputs. Alternatively, the control device can determine a default value for a metering air pressure to be maintained.In the different operating modes, different mode-specific pressure differences between the metering air pressure and the conveying air pressure can be advantageous. Preferably, several mode-specific pressure differences are assigned to a distribution material and / or a distribution material type. The application material can be, for example, granular or grainy application material, such as seed. The material distribution system can have a line system for the conveying air flows, via which the application material is conveyed from the main distribution unit to the metering systems. The adjustment of the conveying air pressure in the respective operating modes of the material distribution system is preferably carried out within the framework of a closed-loop control system, so that the control device can be designed as a closed-loop control device.In a preferred development, the material distribution system according to the invention can be operated in a continuous operating mode, in which application material is supplied to the dosing systems from the main distribution unit, and in an emptying mode, in which the supply of application material to the dosing systems from the main distribution unit is reduced or interrupted compared to the continuous operating mode. The control device is preferably configured to adjust the conveying air pressure such that different mode-specific pressure differences to the dosing pressure are maintained in the continuous operating mode and in the emptying mode. The control device is preferably configured to adjust the conveying air pressure such that a predetermined continuous operating pressure difference to the dosing air pressure is maintained in the continuous operating mode and a predetermined emptying pressure difference to the dosing air pressure is maintained in the emptying mode.In continuous operation mode, the P22-047 application material is conveyed essentially continuously from the main distribution unit to the dosing systems. In emptying mode, the conveyance of the application material from the main distribution unit to the dosing systems is reduced or interrupted, for example due to a completely empty storage container or due to a flow-related interruption in the conveyance of the application material from the main distribution unit to the dosing systems. In a preferred embodiment, the material distribution system according to the invention has at least one conveying air pressure sensor which is designed to determine the conveying air pressure. The conveying air pressure sensor can be arranged upstream of the main distribution unit or downstream of the main distribution unit in the flow direction of the conveying air. The conveying air pressure sensor can also be arranged in the main distribution unit.The material distribution system can comprise a plurality of conveying air pressure sensors, for example, two conveying air pressure sensors, wherein the determined conveying air pressure can be an average value from the sensor values ​​of the conveying air pressure sensors. The conveying air pressure can be monitored by the control device or taken into account as part of a control routine when setting the conveying air pressure. The material distribution system can further comprise at least one metering air pressure sensor configured to determine the metering air pressure. The metering air pressure sensor is preferably arranged upstream of the metering system in the direction of flow of the metering air. The metering air pressure sensor can also be arranged in a metering system. The metering air pressure sensor can also be arranged downstream of the metering system in the direction of flow of the metering air.The material distribution system can comprise a plurality of metering air pressure sensors, for example, two metering air pressure sensors, wherein the determined metering air pressure can be an average value from the sensor values ​​of the metering air pressure sensors. In a further preferred embodiment of the material distribution system according to the invention, the metering systems each comprise a pneumatic separating device, which is configured to be operated by means of a metering air flow and to separate grains of the application material. The metering air pressure sensor can be arranged in a separating device P22-047 of the metering system. Furthermore, the metering air pressure sensor can be arranged upstream or downstream of a separating device of a metering system in the flow direction of the metering air.In a preferred embodiment of the material distribution system according to the invention, the dosing systems each have a material receiving unit configured to receive the application material provided via the conveying air flow and to temporarily store it before being introduced into the singulating device. The material receiving units are preferably configured to interrupt the conveying air supply to the respective dosing system when a specific fill level of temporarily stored application material is reached. Furthermore, a material distribution system according to the invention is advantageous in which the one or more blowers comprise a conveying air blower for generating the conveying air, wherein the control device is configured to control the conveying air blower to adjust the conveying air pressure as a function of the dosing air pressure.The control device is preferably configured to adjust the conveying air pressure via the fan speed of the conveying air fan. Alternatively or additionally, the conveying air pressure can also be adjusted via one or more air pressure control valves between the conveying fan and the main distribution unit or in the main distribution unit. Alternatively or additionally, the conveying air pressure can also be adjusted by setting the maximum supply air volume on the conveying air fan, for example, by adjusting the opening state of an air supply opening. The opening state of the air supply opening can be adjusted, for example, using one or more diaphragm bodies, such as louvres.Furthermore, a material distribution system according to the invention is preferred in which the metering system serves to meter seed and the material distribution system comprises a pneumatic fertilizer conveying device, wherein the conveying air blower is configured to provide conveying air to the fertilizer conveying device for conveying the fertilizer. The conveying air blower thus serves to provide the conveying air for the conveying air flows and to provide the conveying air for conveying the fertilizer. P22-047 In another preferred embodiment of the material distribution system according to the invention, the one or more blowers have a metering air blower for generating the metering air, wherein the control device is configured to control the metering air blower to adjust the metering air pressure.The control device is preferably configured to adjust the conveying air pressure such that a predetermined pressure difference to the metering air pressure is maintained. The pressure difference can be specified by the operator or by the control device. In a preferred development of the material distribution system according to the invention, the main distribution unit can be filled with application material from a storage container, and the fill level of application material in the main distribution unit can be changed and monitored by means of a fill level sensor. The control device can be configured to adjust the conveying air pressure such that, above a critical fill level of application material in the main distribution unit and when the critical fill level of application material in the main distribution unit is reached or below, different fill level-dependent pressure differences to the metering air pressure are maintained.The operating modes of the material distribution system can be assigned to a fill level or a fill level range of application material in the main distribution unit. The control device therefore ensures that the pressure difference to be maintained between the conveying air pressure and the metering air pressure is adjusted if the fill level of application material in the main distribution unit falls below the critical fill level. The fill level sensor can be an empty detector. The critical fill level can also affect the complete emptying of the main distribution unit. The fill level can fall if the main distribution unit is fed with too little application material or if the feeding of application material is interrupted, for example, because the storage hopper is completely empty. When the critical fill level is detected, a small pressure difference is set between the metering air pressure and the conveying air pressure, so that the conveying air pressure is reduced.In this way, it is avoided that P22-047 application material temporarily stored in the material receiving units of the dosing systems is forced into the singling devices, which would interrupt or impair singling due to a blockage of the singling device. Furthermore, a material distribution system according to the invention is preferred in which the one or more blowers comprise a common conveying and dosing blower for generating the conveying air and the dosing air, wherein the control device is configured to divide an air distribution device connected to the conveying and dosing blower for dividing the air flow generated by the conveying and dosing blower into a main conveying air flow and a main dosing air flow. The main conveying air flow is fed to the main distribution unit, so that no separate conveying air blower is required.The main metering air flow is split and then fed to the metering systems, eliminating the need for a separate metering air blower. The air distribution device can have a flap control. The conveying and metering blower can also be configured to generate transport air for conveying another application material, such as fertilizer. In this case, the air distribution device is configured, for example, to divide the air flow generated by the conveying and metering blower into the main conveying air flow, the main metering air flow, and a main transport air flow. The air distribution device can be used, for example, to specify or adjust the free flow cross-sections for the respective flows. The air distribution device can be operated by an electric motor, for example, via one or more electric motors, in particular electric linear motors.In a further preferred embodiment of the material distribution system according to the invention, the control device is designed to set a predetermined pressure difference between the metering air pressure and the conveying air pressure via the fan speed of the conveying and metering fan and / or the free flow cross-section for the main conveying air flow in the air distribution device and / or the free flow cross-section for the main metering air flow in the air distribution device. The free P22-047 flow cross-section for the main conveying air flow and the free flow cross-section for the main metering air flow can preferably be set independently of one another in the air distribution device. In a further preferred embodiment, the material distribution system according to the invention has a plurality of depositing devices which are designed to deposit the application material metered by the metering systems onto the agricultural land.The deposition devices each have at least one curved deposition line configured to guide the metered application material along a curved material guide path toward the agricultural area. The curved deposition line is preferably a curved discharge tube, wherein the curvature of the deposition line causes the application material guided through the deposition line to come into contact with the inner wall of the deposition line, thus ensuring compliance with the material guide path. Furthermore, a material distribution system according to the invention is preferred in which a catch element is arranged behind each of the deposition devices in the direction of travel to catch the application material delivered toward the agricultural area. The catch elements can be, for example, catch rollers.The placement lines and the intercepting elements are preferably aligned with one another in such a way that the spreading material emerging from the placement line is intercepted and immobilized between the soil of the agricultural area and the intercepting element. The use of intercepting elements ensures precise placement of the spreading material on the agricultural area, even with overpressure dosing systems, for example, dosing systems with overpressure singulation, in which high material velocities develop within the placement line. Furthermore, a material distribution system according to the invention is advantageous in which the placement depth of the spreading material is adjustable and the control device is configured to adjust the dosing air pressure depending on the set placement depth.The placement depth of the spreading material can be adjusted, for example, using a depth control device for shares of the P22-047 material distribution system. At shallow sowing depths, it is advantageous to reduce the metered air pressure, since otherwise the air velocity in the placement line becomes too high and the metered spreading material can no longer be reliably intercepted by the intercepting element. The object underlying the invention is further achieved by a spreading machine of the type mentioned above, wherein the material distribution system of the spreading machine according to the invention is designed according to one of the embodiments described above. With regard to the advantages and modifications of the spreading machine according to the invention, reference is first made to the advantages and modifications of the material distribution system according to the invention.The spreading machine can be a seed drill, a fertilizer spreading machine, or a machine for the combined spreading of seed and fertilizer. The spreading machine can be, for example, a mounted machine or a self-propelled machine. If the spreading machine is a mounted machine, the spreading machine can be designed as a towed or mounted machine. The object underlying the invention is further achieved by a method of the type mentioned above, wherein the delivery pressure within the scope of the method according to the invention is adjusted mode-specifically depending on the metering air pressure during a spreading process in several different operating modes of the material distribution system by means of a control device of the material distribution system.The control device preferably adjusts the conveying air pressure during the application process in the respective operating modes such that a mode-specific, predetermined pressure difference to the metering air pressure is maintained in the respective operating modes. The mode-specific pressure differences differ from one another. In a preferred embodiment of the method according to the invention, the material distribution system is operated in a continuous operating mode, in which application material is supplied to the metering systems from the main distribution unit. P22-047 Furthermore, the material distribution system is operated in an emptying mode, in which the supply of application material to the metering systems from the main distribution unit is reduced or interrupted compared to the continuous operating mode.The control device preferably sets the conveying air pressure such that, in continuous operation mode and emptying mode, different mode-specific pressure differences to the metering air pressure are maintained. Preferred embodiments of the invention are explained and described in more detail below with reference to the accompanying drawings. These show: Fig. 1 shows a spreading machine according to the invention in a schematic representation; Fig. 2 shows a material distribution system according to the invention in a schematic representation; Fig. 3 shows another material distribution system according to the invention in a schematic representation; Fig. 4 shows a metering system of a material distribution system according to the invention in a schematic sectional representation; Fig. 5 shows a region of a main distribution unit of a material distribution system according to the invention in a perspective view from below; and Fig.6 Changes in the conveying air pressure and the metering air pressure during the implementation of the method according to the invention. Fig. 1 shows a spreading machine 10 designed as a large-area seed drill, by means of which seed and fertilizer can be applied simultaneously to an agricultural field. The spreading machine 10 comprises a material distribution system 12 for distributing the spreading material within the machine. P22-047 The spreading machine 10 comprises a machine frame 14 on which two storage containers 16, 18 are arranged. The storage container 16 serves to store seed. The storage container 18 serves to store fertilizer, wherein the storage container 18 comprises two container units in which different types of fertilizer can be carried. Below the storage container 16 there is a main distribution unit 20 of the material distribution system 12. The main distribution unit 20 serves to generate several conveying air flows loaded with seed.The conveying air flows are fed to spreading units 24 of the spreading machine 10 via spreading lines 22. For the sake of clarity, only one spreading line 22 is shown, which supplies two spreading units 24 via a T-shaped distributor piece; of course, the remaining spreading units 24 are also supplied via similar spreading lines 22. The spreading units 24 each comprise a seed coulter 26, by means of which a placement furrow for the seed is created in the soil of the agricultural area. Furthermore, the spreading units 24 each comprise a metering system 28, wherein the metering systems 28 are each operated pneumatically with a metering air flow. The metering systems 28 serve to meter the seed conveyed into the metering system 28 via the conveying air flows. The spreading units 24 further comprise depositing devices 30, via which the metered seed is deposited into the deposit furrows created by the seed coulters 26.The application units 24 further comprise fertilizer coulters 32, which serve to create a fertilizer placement furrow. The fertilizer carried in the storage hopper 18 is conveyed to the application units 24 via a fertilizer conveyor 34, from where it is deposited into the placement furrows created by the fertilizer coulters 32. The material distribution system 12 comprises a blower 36, which serves to generate the conveying air for the conveying air flows. The blower 36 is connected to the main distribution unit 20 of the material distribution system 12 via a main conveying air line 38. The blower 36 also serves to generate transport air for conveying the fertilizer to the application units 24. The material distribution system 12 of the application machine 10 also includes a blower 40, which serves to generate the metering air for the metering air flows. The metering systems 28 of the application units 24 can be pneumatically operated using the metering air flows.The material distribution system 12 further comprises a control device 84, which is configured to adjust the conveying air pressure of the conveying air during the application process in several different operating modes of the material distribution system 12 in a mode-specific manner depending on the metering air pressure of the metering air. The control device 84 adjusts the conveying air pressure in the respective operating modes of the material distribution system 12 such that a predetermined mode-specific pressure difference to the metering air pressure is maintained in the respective operating modes, wherein the metering air pressure serves as a reference variable in the respective operating modes. Fig. 2 shows a material distribution system 12 for an agricultural spreading machine 10. The material distribution system 12 comprises a blower 36, which generates a main conveying air flow 46. The main conveying air flow 46 is fed to the main distribution unit 20 via a main conveying air line.The main conveying air line is connected to the air inlet 66 of the main distribution unit 20. Excess air can be discharged into the environment via the adjustable air outlet 72. A storage container 16 for the spreading material 48 is located above the main distribution unit 20. The spreading material 48 can be, for example, seed. The main distribution unit 20 has a material inlet opening 68, through which the spreading material 48 falls into the main distribution unit 20 under the influence of gravity. Within the main distribution unit 20, several conveying air streams 50 loaded with the spreading material 48 are generated, which are discharged from the main distribution unit 20 via the outlets 70. The conveying air flows 50 loaded with application material 48 are fed via application lines to several dosing systems 28, wherein one dosing system 28 is shown as an example in Fig. 2 P22-047.The dosing system 28 is pneumatically operated by a dosing air flow 52 generated by the blower 40 and serves to dose the spreading material 48 conveyed into the dosing system 28 via the conveying air flow 50 before it is deposited on the agricultural land. The dosing system 28 comprises a material receiving unit 42 and a singling device 44. The material receiving unit 42 is configured to receive the spreading material 48 provided via the conveying air flow 50 and to temporarily store it before it is introduced into the singling device 44. Furthermore, the material receiving unit 42 is configured to interrupt the conveying air flow 50 to the dosing system 28 when a specific fill level of temporarily stored spreading material 48 is reached. The separating device 44 is a pneumatically operated separating device which operates according to the principle of overpressure separation.The singling device 44 is configured to be operated by means of the metering air flow 52 and to singulate grains of the application material 48. The material distribution system 12 further comprises a control device 84, which is configured to adjust the conveying air pressure of the conveying air for the conveying air flows 50 during a spreading process in several different operating modes of the material distribution system 12 in a mode-specific manner depending on the metering air pressure of the metering air for the metering air flows 52. The material distribution system 12 can be operated in a continuous operating mode and in an emptying mode. In the continuous operating mode, application material 48 is supplied to the metering systems 28 from the main distribution unit 20. In the emptying mode, the supply of application material 48 to the dosing systems 28 from the main distribution unit 20 is reduced or interrupted compared to the continuous operation mode.The control device 84 adjusts the conveying air pressure such that, in continuous operation mode and emptying mode, different mode-specific pressure differences to the metering air pressure are maintained. The P22-047 control device adjusts the conveying air pressure such that, in continuous operation mode, a predetermined continuous operation pressure difference to the metering air pressure is maintained, and in emptying mode, a predetermined emptying pressure difference to the metering air pressure is maintained. Fig. 3 shows an alternative embodiment of the material distribution system 12, in which the outlets 70 of the main distribution unit 20 are initially connected to a flow divider 54, wherein the flow divider 54 divides the conveying air flow 50 loaded with application material 48, so that two metering systems 28 can be supplied via one outlet 70 on the main distribution unit 20. The blower 40 provides the dosing air flows 52 for the dosing systems 28.The blower 36 further generates another main conveying air flow 64, via which fertilizer can be transported to the application units 24 of the application machine 10. Fig. 4 shows a dosing system 28 of a material distribution system 12. The dosing system 28 comprises a material receiving unit 42 and a singling device 44. The conveying air flow 50 loaded with application material 48 is introduced into the material receiving unit 42 via the inlet nozzle 56. The material receiving unit 42 serves to receive and temporarily store the application material 48 conveyed via the conveying air flow 50. The singling device 44 is a pneumatic singling device that operates according to the principle of overpressure singling. The singling device 44 comprises a singling disc 60, wherein the singling disc 60 has a plurality of grain receiving pockets for receiving and dispensing singulated grains.In alternative embodiments, the singulating device 44 can, for example, also have a singulating drum instead of a singulating disc. The metering air flow 52 for operating the singulating device 44 enters the metering system 28 via the inlet connection 58. The metered application material 48 in the form of separated seeds is then discharged from the metering system 28 via the P22-047 outlet connection 62 and fed to a depositing device 30. The depositing device 30 has a curved depositing line and is configured to deposit the application material 28 metered by the metering system 28 onto the agricultural land. The metering system 28 includes a metering air pressure sensor 78 configured to determine the metering air pressure of the metering air of the metering air flow 52.In alternative embodiments, the dosing air pressure sensor 78 can also be arranged upstream of the dosing system 28 in the flow direction of the dosing air. Fig. 5 shows the housing 82 of a main distribution unit 20. The main distribution unit 20 comprises a conveying air pressure sensor 76, which is configured to determine the conveying air pressure. In other embodiments, the conveying air pressure sensor 76 can also be arranged upstream of the main distribution unit 20 or downstream of the main distribution unit 20 in the flow direction of the conveying air. The main distribution unit 20 can be filled with application material 48 from a storage container 16, wherein the fill level of application material 48 in the main distribution unit 20 can be monitored by means of a fill level sensor 74.The control device 84 is configured to adjust the conveying air pressure of the conveying air such that, above a critical fill level of application material 48 in the main distribution unit 20 and when the critical fill level of application material 48 in the main distribution unit 20 is reached or below, different fill level-dependent pressure differences to the metering air pressure are maintained. Furthermore, the housing 82 of the main distribution unit 20 comprises emptying flaps 80a and 80d, via which the main distribution unit 20 can be emptied, for example, after completion of a spreading process. Fig. 6 shows, by way of example, the pressure curves of the conveying air pressure pF and the metering air pressure pD during a spreading process using a material distribution system 12.Until time t1, the material distribution system 12 is operated in a first operating mode, in which the control device P22-047 84 sets the conveying air pressure pF such that a mode-specific pD serves as the reference variable. The metering air pressure pD changes slightly until time t1, for example because the application machine temporarily detects changes in the application material 48 and these require adjustment of the metering air pressure pD. At time t1, a second operating mode of the material distribution system 12 is set, wherein the control device 84 sets a lower metering air pressure than the conveying air pressure pF in the second operating mode of the material distribution system 12. The setting of the new mode-specific time t2 is completed.For example, the control device 84 has a limit to be observed by comparing it with the remaining area of ​​the agricultural land still to be worked, which results in the material receiving units 42 of the dosing systems 28 being completely emptied at the end of the spreading process.P22-047 Reference number 10 Spreading machine 12 Material distribution system 14 Machine frame 16 Reservoir 18 Reservoir 20 Main distribution unit 22 Spreading lines 24 Spreading units 26 Seed coulters 28 Metering systems 30 Depositing devices 32 Fertilizer coulter 34 Fertilizer conveying device 36 Blower 38 Main conveying air line 40 Blower 42 Material receiving unit 44 Separating device 46 Main conveying air flow 48 Spreading material 50 Conveying air flow 52 Metering air flow 54 Flow divider 56 Inlet nozzle 58 Inlet nozzle 60 Separating disc 62 Outlet nozzle 64 Main conveying air flow 66 Air inlet 68 Material inlet opening 70 Outlets P22-047 72 Air outlet 74 Level sensor 76 Conveying air pressure sensor 78 Dosing air pressure sensor 80a-80d Emptying flaps 82 Housing 84 Control device pF Conveying air pressure pD Dosing air pressure t1, t2 Times p1, p2 Pressure differences P22-047.

Claims

Claims 1. Material distribution system (12) for an agricultural spreading machine (10), comprising - a main distribution unit (20) for generating a plurality of conveying air flows (50) loaded with spreading material (48); - a plurality of metering systems (28), each of which is configured to be pneumatically operated by means of a metering air flow (52) and to meter the spreading material (48) conveyed into the metering system (28) via one of the conveying air flows (50); and - one or more fans (36, 40) configured to generate the conveying air, which has a conveying air pressure (pF), for the conveying air flows (50) and the metering air, which has a metering air pressure (pD), for the metering air flows (52); characterized by a control device (84) configured toto adjust the conveying air pressure (pF) during a spreading process in several different operating modes of the material distribution system (12) in a mode-specific manner depending on the dosing air pressure (pD).

2. Material distribution system (12) according to claim 1, characterized in that the material distribution system (12) is operable in a continuous operation mode, in which application material (48) is supplied to the dosing systems (28) from the main distribution unit (20), and in an emptying mode, in which the supply of application material (48) to the dosing systems (28) from the main distribution unit (20) is reduced or interrupted compared to the continuous operation mode, wherein the control device (84) is configured to adjust the conveying air pressure (pF) such that, in the continuous operation mode and the emptying mode, different mode-specific pressure differences (p1, p2) to the dosing air pressure (pD) are maintained. P22-047, 3. The material distribution system (12) according to claim 1 or 2, characterized by - at least one conveying air pressure sensor (76) configured to determine the conveying air pressure (pF); and / or - at least one metering air pressure sensor (78) configured to determine the metering air pressure (pD).

4. The material distribution system (12) according to any one of the preceding claims, characterized in that the one or more blowers (36, 40) comprise a conveying air blower (36) for generating the conveying air, wherein the control device (84) is configured to control the conveying air blower (36) to adjust the conveying air pressure (pF) as a function of the metering air pressure (pD). 5.Material distribution system (12) according to claim 4, characterized in that the metering systems (28) serve for metering seed, and the material distribution system (12) comprises a pneumatic fertilizer conveying device (34), wherein the conveying air blower (36) is configured to provide conveying air to the fertilizer conveying device (34) for conveying the fertilizer. 6.Material distribution system (12) according to one of the preceding claims, characterized in that the main distribution unit (20) can be filled with application material (48) from a storage container (16) and the fill level of application material (48) in the main distribution unit (20) can be changed and monitored by means of a fill level sensor (74), wherein the control device (84) is designed to adjust the conveying air pressure (pF) in such a way that above a critical fill level of application material (48) in the main distribution unit (20) and when reaching or below the critical fill level of application material (48) in the main distribution unit (20), different fill level-dependent pressure differences (p1, p2) to the metering air pressure (pD) are maintained.

7. Material distribution system (12) according to one of the preceding claims, characterized by a plurality of depositing devices (30) configured to deposit the spreading material (48) metered by the metering systems (28) onto the agricultural area, wherein the depositing devices (30) each have at least one curved depositing line configured to guide the metered spreading material (48) along a curved material guide path toward the agricultural area.

8. Material distribution system (12) according to claim 7, characterized in that a respective intercepting element for intercepting the spreading material (48) delivered toward the agricultural area is arranged behind the depositing devices (30) in the direction of travel. 9.Material distribution system (12) according to one of the preceding claims, characterized in that the placement depth of the spreading material (48) is adjustable and the control device (84) is configured to adjust the metering air pressure (pD) depending on the set placement depth.

10. Spreading machine (10) for spreading spreading material (48) on an agricultural area, comprising - a storage container (16) for the spreading material (48); - a plurality of spreading units, and - a material distribution system (12) for distributing the spreading material (48) from the storage container (16) to the plurality of spreading units; characterized in that the material distribution system (12) is designed according to one of the preceding claims.

11. A method for distributing spreading material (48) from a storage container (16) to a plurality of spreading units of a spreading machine (10) by means of a material distribution system (12), in particular a material distribution system (12) according to one of claims 1 to 9, comprising the steps of: - generating a plurality of conveying air flows (50) loaded with spreading material (48) by means of a main distribution unit (20) of the material distribution system (12); - supplying conveying air flows (50) loaded with spreading material (48) to pneumatically operated dosing systems (28) of the material distribution system (12); - dosing the spreading material (48) conveyed to the dosing systems (28) via the conveying air flows (50) by means of the dosing systems;and - generating the conveying air having a conveying air pressure (pF) for the conveying air flows (50) and the dosing air having a metering air pressure (pD) for the metering air flows (52) by means of one or more blowers (36, 40) of the material distribution system (12); characterized in that the conveying air pressure (pF) is adjusted during a discharge process in several different operating modes of the material distribution system (12) by means of a control device (84) of the material distribution system (12) in a mode-specific manner as a function of the metering air pressure (pD).

12. The method according to claim 10, characterized by the following steps: - operating the material distribution system (12) in a continuous operation mode in which application material (48) is supplied to the dosing systems (28) from the main distribution unit (20), and - operating the material distribution system (12) in an emptying mode in which the supply of application material; (48) to the dosing systems (28) from the main distribution unit (20) is reduced or interrupted compared to the continuous operation mode, wherein the control device (84) sets the conveying air pressure (pF) in such a way that in the continuous operation mode and in the emptying mode, different mode-specific pressure differences (p1, p2) to the dosing air pressure (pD) are maintained.

Images