Metering system and metering method of agricultural spreader

Abstract

The invention relates to a metering system (10) for an agricultural spreader (100), comprising: an equipment assembly (16) comprising at least one airflow generator (18, 20, 42) for generating a conveying airflow (FLS) and a metering airflow (DLS) flowing in a conveying direction; a metering device (26, 26a, 26b) configured to meter the spread material with a sub-metering gas flow generated by the metering gas flow (DLS); and a spreading system (22), by means of which the spread material can be conveyed from the storage container (12, 14) to the metering device (26, 26a, 26b).

Description

[0001] The present invention relates to a metering system for an agricultural spreader according to the preamble of claim 1, and a method for metering spread materials according to the preamble of claim 11.

[0002] Conventional metering systems typically include a device assembly with at least one airflow generator. This assembly generates a conveying airflow and a metering airflow along the conveying direction. The metering device then uses a portion of the metering airflow generated by the metering airflow to meter the material to be spread. The spread material is conveyed from a storage container to the metering device via the conveying airflow.

[0003] In known metering systems, especially when metering fine seeds such as rapeseed, there is a risk that if the conveying airflow weakens or disappears, the spread material may flow in the opposite direction to the airflow, and consequently towards the airflow generator. This backflow of spread material can damage the airflow generator. Furthermore, there is a risk that the spread material may be accidentally expelled from the airflow generator, thus falling uncontrollably onto the farmland.

[0004] If the conveying airflow is generated hydraulically through the tractor's hydraulic system, under certain operating conditions (e.g., when hydraulically lifting the spreader's implement carrier), sufficient hydraulic power may not be provided to generate adequate conveying airflow, which could cause material to flow back through the metering airflow.

[0005] Therefore, the objective of this invention is to prevent the spread material from unexpectedly flowing back in the opposite direction to the conveying direction when the conveying airflow weakens or disappears.

[0006] The above-mentioned metering system can solve this technical problem. The metering system of the present invention includes an anti-backflow device. With the aid of the anti-backflow device, when the conveying airflow weakens or disappears, the spreading material located in the spreading system can be prevented from entering the airflow generator of the equipment component by one or more metering airflows flowing in the opposite direction to the conveying direction.

[0007] This anti-backflow device effectively prevents the spread material from flowing back and damaging the airflow generator, while also preventing accidental discharge of the spread material from the airflow generator. A weakening or disappearance of the conveying airflow may stem from interruptions or limitations in the airflow generation process, or from malfunctions (such as pipeline failures or leaks). Especially during the start-up and shutdown switching of the airflow generator, the conveying airflow may weaken or disappear, while the metering airflow continues to be actively generated. Under normal operating conditions, the partial conveying airflow generated by the conveying airflow and the partial metering airflow generated by the metering airflow merge within the metering device, allowing the spread material to be transported towards the farmland using the merged airflow. For example, the airflow generator can be configured as a blower.

[0008] In a preferred embodiment of the metering system of the present invention, the anti-backflow device includes at least one movable or deformable shut-off valve; by means of this shut-off valve, the free flow cross section within the anti-backflow device can be partially or completely closed. Preferably, the anti-backflow device is a passive component and cannot be controlled by an electronic control device. The anti-backflow device may include one or more pivotable shut-off valves. At least one movable shut-off valve is preferably rotatable within the flow cross section. For example, when the shut-off valve is fully open, its direction is parallel to the flow direction. The shut-off valve may be a disc-shaped element. The shut-off valve may be a central shut-off valve. The shut-off valve may be a single-eccentric, double-eccentric, or triple-eccentric shut-off valve. The anti-backflow device may include one or more limiting elements for the one or more shut-off valves. The shut-off valve may be made of an elastically deformable material, in which case the opening and closing of the free flow cross section is achieved by the deformation of the shut-off valve. For example, the anti-backflow device may be configured as a check valve.

[0009] In another preferred embodiment of the metering system of the present invention, the anti-backflow device is configured to be driven by airflow passing through it. When airflow passes through the anti-backflow device in the conveying direction, the anti-backflow device is preferably in an open state; in this state, airflow containing the spread material can flow through the anti-backflow device. When airflow flows through or rushes towards the anti-backflow device in the opposite direction to the conveying direction, the anti-backflow device is in a closed state; in this state, the spread material cannot flow through or pass through the anti-backflow device. In the closed state, the anti-backflow device can be configured to either prevent airflow from passing through or allow airflow to still pass through it (especially in cases of height restriction), thereby creating high flow resistance in the opposite direction to the conveying direction. The anti-backflow device may include a blocking device (especially a blocking valve), the flow resistance of which depends on the conveying direction; therefore, the blocking device is preferably driven only by airflow passing through it. For example, such a blocking device may have low flow resistance in the flow direction, allowing the conveying airflow to flow through with almost no loss; while in the opposite direction of flow, the blocking device may have high flow resistance, thereby preventing the airflow containing the spread material from passing through.

[0010] In another preferred embodiment of the metering system described in this invention, the anti-backflow device includes an active controllable actuator for turning the device on and / or off. The actuator may include a controllable actuating element and may be an electrically, pneumatically, or hydraulically driven actuator. In this embodiment, the anti-backflow device may also function as an active controllable throttling device for regulating airflow along the conveying direction and against the conveying direction.

[0011] In another preferred embodiment of the metering system of the present invention, the spreading system includes a main spreading unit; spreading material and conveying airflow can be introduced into the main spreading unit, and the main spreading unit is configured to distribute the spreading material into multiple streams of conveying airflow generated by the conveying airflow. The main spreading unit preferably includes at least one inlet for conveying airflow and multiple outlets for distributing the conveying airflow. Furthermore, the main spreading unit preferably includes an inlet for spreading material. The main spreading unit is preferably located below the spreading material storage container so that the spreading material can enter the main spreading unit through the inlet under gravity.

[0012] In another preferred embodiment of the metering system of the present invention, the equipment component includes a conveying airflow generator for generating conveying airflow and a metering airflow generator for generating metering airflow. An anti-backflow device is preferably disposed between the conveying airflow generator of the equipment component and the main spreading unit of the spreading system. The conveying airflow generator is preferably a conveying fan, and the metering airflow generator is preferably a metering fan.

[0013] Furthermore, the present invention preferably provides a metering system in which an anti-backflow device is disposed between the main dispensing unit of the dispensing system and the metering device. In this case, the individual dispensing airflows can be further divided into multiple (e.g., two) dispensing airflows by a diversion device. The diversion device can be, for example, a Y-type connector, and the anti-backflow device can be integrated within the diversion device.

[0014] Furthermore, the metering system of the present invention has an advantageous aspect: the equipment components include an airflow generator for generating a main airflow, and an airflow diverter for generating a conveying airflow and a metering airflow from the main airflow. The airflow diverter may include one or more switches or baffles for dividing the main airflow into a conveying airflow and a metering airflow. In this case, the following situation may occur: at a specific switch or baffle position, a strong metering airflow is generated, while the conveying airflow weakens or disappears, which may cause material to flow back in the opposite direction to the conveying direction. To address this situation, an anti-backflow device can be used to prevent the spread material in the spreading system from entering the airflow generator of the equipment components.

[0015] In another preferred embodiment of the metering system of the present invention, the anti-backflow device may be disposed between the airflow distributor of the equipment component and the main spreading unit of the spreading system, or between the airflow generator of the equipment component and the airflow distributor of the equipment component. If the anti-backflow device is disposed between the airflow distributor of the equipment component and the main spreading unit of the spreading system, the material backflow will not enter the airflow distributor of the equipment component, and thus will not enter the airflow generator. If the anti-backflow device is disposed between the airflow generator of the equipment component and the airflow distributor of the equipment component, when material backflow occurs, the spreading material may enter the airflow distributor of the equipment component, but cannot enter the airflow generator of the equipment component.

[0016] Furthermore, the present invention preferably provides a metering system in which the metering device is configured to operate under overpressure. This metering device may include a rotary-driven metering rotor, which may be a metering disc or a metering drum. Alternatively, the metering device may be a separation device operating under overpressure, which may include a rotary-driven separation disc or a separation drum.

[0017] The objective of this invention is further addressed by a method of the type mentioned at the beginning. Within the scope of the method described in this invention, when the conveying airflow weakens or disappears, backflow prevention devices of the metering system are used to prevent the spreading material located within the spreading system from entering the airflow generator of the equipment components through one or more separate metering airflows flowing in the opposite direction to the conveying direction. For example, the method described in this invention can be implemented using the metering system in any of the above embodiments. Therefore, regarding the advantages and variations of the method described in this invention, reference can first be made to the advantages and variations of the metering system described in this invention.

[0018] In a preferred embodiment of the method described in this invention, the anti-backflow device is driven by airflow passing through it. The closed state of the anti-backflow device preferably depends on the flow direction of the airflow passing through or towards it. Alternatively or supplementary, the actuator of the anti-backflow device can be actively controlled to enable and / or disable the device.

[0019] In another preferred embodiment of the method described in this invention, the spreading material and conveying airflow are introduced into the main spreading unit of the spreading system, which distributes the spreading material into multiple conveying airflows generated by the conveying airflow. Preferably, backflow of the spreading material is prevented by means of an anti-backflow device disposed between the conveying airflow generator of the equipment assembly and the main spreading unit of the spreading system. Alternatively, backflow of the spreading material is prevented by means of an anti-backflow device disposed between the main spreading unit of the spreading system and the metering device.

[0020] The method of the present invention also has an advantageous improvement: the equipment component includes an airflow generator for generating a main airflow, and a conveying airflow and a metering airflow are generated from the main airflow by means of an airflow splitter. Backflow of the spread material is prevented by means of an anti-backflow device, which is preferably located between the airflow splitter of the equipment component and the main spreading unit of the spreading system. Alternatively, backflow of the spread material is prevented by means of an anti-backflow device located between the airflow generator and the airflow splitter of the equipment component.

[0021] The preferred embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. The drawings show:

[0022] Figure 1A schematic diagram of a spreader employing the metering system according to the present invention;

[0023] Figure 2 A schematic diagram of the metering system according to the present invention;

[0024] Figure 3 A schematic diagram of another metering system according to the present invention;

[0025] Figure 4 A schematic diagram of yet another metering system according to the present invention;

[0026] Figure 5 A schematic diagram of another metering system according to the present invention;

[0027] Figure 6 A schematic diagram of the main dispensing unit of the metering system according to the present invention, wherein the main dispensing unit includes an anti-backflow device;

[0028] Figure 7 A schematic diagram of the backflow prevention device of the metering system according to the present invention in the open state;

[0029] Figure 8 Figure 7 The diagram shows the anti-backflow device in the off state.

[0030] Figure 1 An agricultural spreader 100 is shown, which can spread two different spreading materials, such as seeds and fertilizer, onto farmland.

[0031] The agricultural spreader 100 is a hook-and-loop type, which can be attached to a towing vehicle (such as a tractor) via a tow bar. The tow bar is connected to the main frame 102 of the spreader 100. The main frame 102 carries the storage containers 12 and 14 of the spreader 100's metering system 10. The storage containers 12 and 14 can be used to hold the spread material to be applied to the farmland. For example, storage container 12 can be filled with granular fertilizer. For example, storage container 14 can be filled with seeds.

[0032] The main frame 102 is connected to the implement support frame 104 of the spreader 100. Multiple spreading devices are arranged side-by-side on the implement support frame 104, through which the spreading material loaded in the storage containers 12 and 14 can be spread onto the farmland according to a metering method. The spreading devices can be, for example, seeding furrow openers and fertilizer furrow openers, wherein the seeding furrow openers and fertilizer furrow openers can be, for example, disc furrow openers or toothed furrow openers.

[0033] The metering system 10 of the spreader 100 includes an equipment assembly 16, which comprises a conveying airflow generator 18 and a metering airflow generator 20. The conveying airflow generator 18 generates a conveying airflow FLS flowing in the conveying direction; the metering airflow generator 20 generates a metering airflow DLS. A plurality of metering devices 26 are also provided on the implement carrier 104, which are used to meter the spread material using sub-metering airflows DLS generated by the metering airflow DLS. The metering system 10 of the spreader 100 also includes a spreading system 22, by which the spread material is conveyed from one of the storage containers 12, 14 to the metering device 26 via the conveying airflow FLS.

[0034] The spreading system 22 includes a main spreading unit 24 disposed below the storage containers 12 and 14. The spreading material loaded in the storage containers 12 and 14 enters the main spreading unit 24 under gravity. A conveying airflow (FLS) generated by the conveying airflow generator 18 is also supplied to the main spreading unit 24 via the conveying air line 28. The main spreading unit 24 is configured to distribute the spreading material into multiple conveying airflows (FLTS) generated by the conveying airflow.

[0035] When metering fine seeds such as rapeseed, there is a risk that if the conveying airflow weakens or disappears, the spread material may flow back towards the conveying airflow generator 18 in the opposite direction to the conveying direction under the influence of the metering airflow. This backflowing spread material may damage the conveying airflow generator 18; furthermore, the spread material may be accidentally discharged from the conveying airflow generator 18, ultimately falling uncontrollably onto the farmland. To prevent this, the metering system 10 includes an anti-backflow device 32. When the conveying airflow FLS weakens or disappears, this anti-backflow device 32 prevents the spread material located in the spreading system 22 from entering the conveying airflow generator 18 of the equipment assembly 16 by one or more streams of metering airflow flowing in the opposite direction to the conveying direction. The anti-backflow device 32 effectively prevents the spread material from flowing back and damaging the conveying airflow generator 18, while also preventing the spread material from being accidentally discharged from the conveying airflow generator 18.

[0036] The metering system 10 also includes a control device 30, which contains electronic data processing equipment. The metering process performed by the metering system 10 can be adjusted via the control device 30. The anti-backflow device 32 can be configured as either a passive, uncontrollable component or an active, controllable component. If the anti-backflow device 32 is an active, controllable component, control commands can be sent via the electronic control device 30 to control the on / off state of the gas delivery line 28; if the anti-backflow device 32 is a passive, uncontrollable component, its opening state can depend, for example, on the direction of airflow or the direction of inflow.

[0037] Figure 2 The metering system 10 is shown, in which the conveying airflow generator 18 of the equipment component 16 generates a conveying airflow FLS. The conveying airflow FLS enters the anti-backflow device 32 through the pipe section 28a of the conveying air line 28, and then enters the main spreading unit 24 of the spreading system 22 through the pipe section 28b from the anti-backflow device 32. The conveying airflow FLS flows through the anti-backflow device 32 in the conveying direction, wherein the anti-backflow device 32 is configured to not block the airflow when it flows in the conveying direction.

[0038] The main distribution unit 24 is provided with an air inlet for the conveying airflow FLS. In addition, the main distribution unit 24 includes an upper feed inlet for the distributed material. Inside the main distribution unit 24, the conveying airflow FLS is divided into multiple sub-conveyor airflows FLTS; for illustration purposes, only one sub-conveyor airflow FLTS is shown in the figure. The sub-conveyor airflow FLTS flowing out of the main distribution unit 24 carries the distributed material, forming a material flow MS. The sub-conveyor airflow carrying the distributed material is further divided by the diverter 36, forming sub-conveyor airflows FLTS1 and FLTS2, and material flows MS1 and MS2. Sub-conveyor airflow FLTS1 is delivered to the metering device 26a, and sub-conveyor airflow FLTS2 is delivered to the metering device 26b.

[0039] Metering devices 26a and 26b are pneumatically driven. To achieve pneumatic drive for metering devices 26a and 26b, the metering airflow generator 20 in equipment assembly 16 generates a metering airflow DLS. The metering airflow DLS is delivered to a metering airflow splitter 38, which divides the metering airflow DLS into multiple sub-metering airflows DLTS. Subsequently, each sub-metering airflow DLTS is delivered to its corresponding metering device 26a or 26b, enabling each metering device 26a or 26b to operate using the delivered sub-metering airflow DLTS.

[0040] Metering devices 26a and 26b can be, for example, overpressure driven separation devices. In this case, the dispensing material is seeds, which are separated within metering devices 26a and 26b by overpressure. The separate conveying airflow (FLTS) and separate metering airflow (DLTS) delivered to each metering device 26a and 26b converge within the metering devices 26a and 26b and are used to guide the metered dispensing material toward the farmland. The outlets of metering devices 26a and 26b can be connected to a discharge channel, through which the metered dispensing material is discharged toward the farmland.

[0041] If the conveying airflow FLS weakens or is interrupted, the distributed material can be conveyed towards the conveying airflow generator 18 via the main distribution unit 24 in the opposite direction to the conveying direction under the action of the metering airflow DLTS. In this case, the anti-backflow device 32 installed between pipe sections 28a and 28b of the conveying air pipeline 28 can prevent the distributed material from entering the conveying airflow generator 18, thereby effectively avoiding damage to the conveying airflow generator 18 due to the entry of the distributed material. In addition, it can also prevent the distributed material from entering the farmland in an uncontrolled manner through the conveying airflow generator 18.

[0042] Figure 3 The metering system 10 is shown, wherein an anti-backflow device 32 is disposed between the main spreading unit 24 and the metering devices 26a and 26b. In this configuration, multiple anti-backflow devices 32 are required to completely prevent material from flowing back in the direction toward the conveying airflow generator 18.

[0043] exist Figure 4 In the metering system 10 shown, the delivery airflow FLS and the metering airflow DLS are generated by the airflow generator 42 of the equipment assembly 16. The airflow generator 42 generates the main airflow HLS, which is sent to the airflow splitter 40 of the equipment assembly 16 through the main air line 34. The airflow splitter 40 divides the main airflow HLS into the metering airflow DLS and the delivery airflow FLS.

[0044] In this structure, the anti-backflow device 32 is disposed between the airflow diverter 40 and the main spreading unit 24 to prevent the spreading material located in the spreading system 22 from entering the airflow diverter 40 and the airflow generator 42.

[0045] exist Figure 5 In the metering system 10 shown, the anti-backflow device 32 is disposed between pipe sections 34a and 34b of the main air pipe 34. Therefore, the anti-backflow device 32, located between the airflow splitter 40 and the airflow generator 42, prevents the spread material in the spreading system 22 from entering the airflow generator 42. It is conceivable that, in embodiments not shown, the anti-backflow device 32 may be integrated into the airflow splitter 40, or may perform both functions as a single component, or the anti-backflow device 32 may be part of the airflow generator 42.

[0046] Figure 6 The gas delivery line 28 leading to the main dispensing unit 24 is shown, and the gas delivery line 28 is equipped with an anti-backflow device 32.

[0047] Figure 7 and Figure 8As shown, the anti-backflow device 32 includes a pipe section 44, within which two movable shut-off valves 46a and 46b are provided. These two movable shut-off valves 46a and 46b can close the free flow section within the anti-backflow device 32. Therefore, in this embodiment, the anti-backflow device 32 is a passive component and cannot be controlled by an electronic control device. The shut-off valves 46a and 46b can pivot and rotate within the flow section.

[0048] Figure 7 The backflow prevention device 32 is shown to be in the open position. In the open position, the pivotable shut-off valves 46a and 46b are oriented parallel to the flow direction.

[0049] Figure 8 In this process, the airflow flows through or rushes towards the anti-backflow device 32 in the opposite direction to the conveying direction, causing the shut-off valves 46a and 46b to essentially completely block the free flow section. The pipe section 44 is equipped with limiting elements 48a and 48b for the shut-off valves 46a and 46b. These limiting elements 48a and 48b ensure that when the airflow flows in the opposite direction to the conveying direction, the shut-off valves 46a and 46b remain in the closed position shown in the figure.

[0050] Therefore, the shut-off valves 46a and 46b are driven solely by the airflow passing through the anti-backflow device 32, and the specific driving method depends on the direction of air delivery. Alternatively, it is conceivable to use at least one actuator to drive the shut-off valves 46a and 46b.

[0051] Furthermore, in an embodiment not shown, the shut-off valves 46a and 46b can be replaced with other types of shut-off devices. The flow resistance of this shut-off device depends on the conveying direction; therefore, it is preferably actuated only by the airflow passing through it. This characteristic can be achieved by the following technical means: the shut-off device has low flow resistance in the flow direction, allowing the conveying airflow to flow through at least almost without loss; while in the opposite direction, the shut-off device has high flow resistance, thereby preventing the airflow containing the spread material from passing through.

[0052] The blocking device may include at least one diaphragm, a partial spherical shell, an eccentric baffle, a sheet, or a grid.

[0053] Explanation of reference numerals in the attached figures

[0054] 10. Metering System

[0055] 12 Storage Containers

[0056] 14 Storage Containers

[0057] 16 Equipment Components

[0058] 18. Conveyor airflow generator

[0059] 20 Metering airflow generator

[0060] 22 Dispensing System

[0061] 24 Main Dispensing Units

[0062] Measuring devices 26, 26a, 26b

[0063] 28 Gas delivery pipeline

[0064] Pipeline sections 28a and 28b

[0065] 30 Control device

[0066] 32 Anti-backflow device

[0067] 34 Main gas pipeline

[0068] Pipeline sections 34a and 34b

[0069] 36 Diverter

[0070] 38. Metering airflow splitter

[0071] 40 Airflow Diverter

[0072] 42. Airflow generator

[0073] 44 pipe sections

[0074] 46a, 46b shut-off valves

[0075] 48a, 48b limiting components

[0076] 100 Spreader

[0077] 102 Main Frame

[0078] 104 Agricultural implement support frame

[0079] DLS metering airflow

[0080] DLTS Flow Measurement

[0081] FLS delivery airflow

[0082] FLTS, FLTS1, and FLTS2 are used to separate the airflow.

[0083] MS, MS1, MS2 material flow

[0084] HLS Main airflow

Claims

1. A metering system (10) for an agricultural spreader (100), comprising: The equipment component (16) includes at least one airflow generator (18, 20, 42) for generating a delivery airflow (FLS) and a metering airflow (DLS), the delivery airflow (FLS) flowing in the delivery direction; Metering devices (26, 26a, 26b) configured to meter spread material using a sub-metering airflow (DLTS) generated by the metering airflow (DLS); and The spreading system (22) enables the spreading material to be conveyed from the storage containers (12, 14) to the metering devices (26, 26a, 26b) via the conveying airflow (FLS); The metering system is characterized by including an anti-backflow device (32), which, when the conveying airflow (FLS) weakens or disappears, can prevent the spreading material located in the spreading system (22) from entering the airflow generator (18, 20, 42) of the equipment assembly (16) by means of one or more sub-metering airflows flowing in the opposite direction to the conveying direction.

2. The metering system (10) according to claim 1, characterized in that, The backflow prevention device (32) includes at least one movable or deformable blocking valve (46a, 46b), which can partially or completely close the free flow section within the backflow prevention device (32).

3. The metering system (10) according to claim 1 or 2, characterized in that, The anti-backflow device (32) is configured to be driven by the airflow flowing through it.

4. The metering system (10) according to any one of the preceding claims, characterized in that, The backflow prevention device (32) includes an active controllable actuator for opening and / or closing the backflow prevention device (32).

5. The metering system (10) according to any one of the preceding claims, characterized in that, The spreading system (22) includes a main spreading unit (24), the spreading material and the conveying airflow (FLS) can be introduced into the main spreading unit, and the main spreading unit is configured to distribute the spreading material into multiple conveying airflows (FLTS, FLTS1, FLTS2) generated by the conveying airflow.

6. The metering system (10) according to claim 5, characterized in that, The device component (16) includes a delivery airflow generator (18) for generating the delivery airflow (FLS) and a metering airflow generator (20) for generating the metering airflow (DLS). The anti-backflow device (32) is disposed between the conveying airflow generator (18) of the equipment assembly (16) and the main spreading unit (24) of the spreading system (22).

7. The metering system (10) according to claim 5, characterized in that, The anti-backflow device (32) is disposed between the main spreading unit (24) and the metering device (26, 26a, 26b) of the spreading system (22).

8. The metering system (10) according to claim 5, characterized in that, The device assembly (16) includes an airflow generator (42) for generating a main airflow (HLS) and an airflow splitter (40) for generating the delivery airflow (FLS) and the metering airflow (DLS) from the main airflow (HLS).

9. The metering system (10) according to claim 8, characterized in that, The anti-backflow device (32) is located between the airflow splitter (40) of the equipment assembly (16) and the main spreading unit (24) of the spreading system (22), or between the airflow generator (42) of the equipment assembly (16) and the airflow splitter (40) of the equipment assembly (16).

10. The metering system (10) according to any one of the preceding claims, characterized in that, The metering devices (26, 26a, 26b) are configured to operate under overpressure conditions.

11. A method for metering spread material using a metering system (10) of an agricultural spreader (100), particularly using a metering system (10) according to any one of the preceding claims, comprising the following steps: The metering system (10) generates a delivery airflow (FLS) and a metering airflow (DLS) by means of a device component (16) including at least one airflow generator (18, 20, 42), the delivery airflow (FLS) flowing in the delivery direction; The metering device (26, 26a, 26b) of the metering system (10) uses the sub-metering airflow (DLTS) generated by the metering airflow (DLS) to meter the spread material; and The spreading material is transported from the storage containers (12, 14) to the metering device (26, 26a, 26b) by means of the spreading system (22) of the metering system (10) and the conveying airflow (FLS); Its characteristics include the following steps: When the conveying airflow (FLS) weakens or disappears, the backflow prevention device (32) of the metering system (10) prevents the spreading material located in the spreading system (22) from entering the airflow generator (18, 20, 42) of the equipment assembly (16) by means of one or more sub-metering airflows flowing in the opposite direction to the conveying direction.

12. The method according to claim 11, characterized in that: The backflow prevention device (32) is driven by the airflow passing through it; and / or The actuator of the backflow prevention device (32) is actively controlled to open and / or close the backflow prevention device (32).

13. The method according to claim 11 or 12, characterized in that, The spreading material and the conveying airflow (FLS) are introduced into the main spreading unit (24) of the spreading system (22), and the main spreading unit distributes the spreading material into multiple conveying airflows (FLTS, FLTS1, FLTS2) generated by the conveying airflow (FLS). The backflow prevention device (32) is used to prevent the spread material from flowing back. Between the conveying airflow generator (18) of the device assembly (16) and the main spreading unit (24) of the spreading system (22); or Between the main spreading unit (24) of the spreading system (22) and the metering device (26, 26a, 26b).

14. The method according to claim 11 or 12, characterized in that, The device component (16) includes an airflow generator (42) for generating a main airflow (HLS), and generates the delivery airflow (FLS) and the metering airflow (DLS) from the main airflow (HLS) by means of an airflow splitter (40). The backflow prevention device (32) is used to prevent the spread material from flowing back. The backflow prevention device (32) is as follows: Between the airflow splitter (40) of the device assembly (16) and the main spreading unit (24) of the spreading system (22); or Between the airflow generator (42) and the airflow splitter (40) of the device assembly (16).

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