Method for monitoring a crop flow, and harvester

Abstract

A method for monitoring a crop flow in a direction of conveyance for crops of a harvester, and harvester having a direction of conveyance for crops and comprising a device for monitoring a crop flow in the direction of conveyance.

Description

[0001] Method for monitoring a crop flow and harvesting machine

[0002] Description

[0003] The application relates to a method for monitoring a crop flow in a conveyor device for crop of a harvesting machine and to a harvesting machine.

[0004] In the combine harvester, a uniform intake of crop is the basis for a uniform crop flow in the threshing units and thus for optimal utilization of the harvester.

[0005] EP 3 714 674 A1 describes a system and method for controlling a combine harvester. The method comprises the steps of receiving grain flow sensor signals from a plurality of grain flow sensors, determining a current load on a walker section based on the received grain flow sensor signals, and adjusting an aggressiveness setting of a threshing and separating section of the combine harvester based on the current load. The grain flow sensors are provided below and adjacent to a crop transfer surface of the walker section of the combine harvester and are distributed along a length of the walker section.

[0006] Sudden changes in harvesting conditions in the field, as well as foreign objects or soil ingestion by the header, can disrupt crop flow. In combine harvesting, the most common method for detecting crop flow disturbances in the header is for the operator to observe the crop flow. The trend toward ever-increasing working widths and ever-increasing forward speeds makes this task more difficult for the operator.

[0007] One object may be to improve crop flow monitoring. This object is achieved by a method according to claim 1 and by a harvesting machine according to claim 10. Embodiments are described in the subclaims.

[0008] In the method for monitoring a crop flow in a conveyor device for crops of a harvesting machine, an electrical or dielectric conductivity of the crop flow of the conveyed crop is measured using at least one conductivity sensor in the conveyor device, and a signal representing the measured conductivity is generated. The signal is analyzed using an evaluation device, wherein the crop flow is evaluated based on a development of at least one of the following signal properties: noise frequency, noise amplitude, and baseline signal. The baseline signal corresponds to an average electrical conductivity of the crop flow. The currently measured conductivity varies greatly due to movement, which is referred to as noise. Noise amplitude and noise frequency also vary within certain limits.A change in noise amplitude and noise frequency within the meaning of the application occurs as soon as a predetermined threshold value of the change is reached.

[0009] The method for monitoring the crop flow advantageously allows for the automatic detection of crop flow disturbances and offers the following benefits. Firstly, the workload is reduced for the harvester driver, as they do not have to constantly concentrate on monitoring the crop flow across the entire working width in difficult harvesting conditions. This increases comfort and counteracts driver fatigue. Secondly, the early detection of crop flow disturbances provides the opportunity to counteract the disturbance. In the case of soil accumulation, for example, the cutting height can be adjusted at short notice to prevent the crop from accumulating and to allow the accumulation to dissipate. Crop flow disturbances are detected earlier and are less severe. Ultimately, the harvester downtime is reduced.Detecting pulsating crop flow by varying the straw length makes it possible to automatically adjust the cutting table length on so-called Vario headers. This ensures a more even crop flow and better machine utilization. According to one embodiment, the following sensors can be used to detect crop flow disturbances. The working width of the header is divided into segments. Each segment is monitored by a sensor. All signals from the sensors in the segments are fed to a central evaluation unit and evaluated. For example, conductivity sensors are used, which are in contact with the crop flow. The cutting table is suitable for placing the sensors, whereby the crop flow is guided over the sensors. The conductivity sensors can be based on methods for measuring electrical conductivity, dielectric conductivity, or capacitive conductivity.

[0010] The conductivity of the crop is largely determined by its water content. The electrical conductivity and dielectric constant of water are significantly higher than that of dry biomass. Furthermore, the conductivity measurement is also influenced by the density of the material being measured, as well as the distance of the material from the sensor, or the contact with the sensor. Changes in the density of the material are, in turn, determined by the amount of crop and the compression of the crop. Density and sensor contact change with high dynamics in the crop flow. It is to be expected that the signal from a conductivity sensor is composed of a base signal level and a noise component.

[0011] According to a further embodiment, a reduction in the noise frequency indicates a reduced flow velocity of the crop stream.

[0012] According to a further embodiment, if the noise amplitude decreases while the base signal increases, it is concluded that there is a higher water content in the crop flow, wherein in particular if a limit value of the reduction in the noise amplitude and / or the increase in the base signal is reached, it is concluded that there is an accumulation of soil in the conveying device.

[0013] According to a further embodiment, the conductivity of the crop flow of the conveyed crop is measured with a plurality of conductivity sensors spaced apart from one another, wherein a signal representing the measured conductivity is generated for each conductivity sensor and wherein the signals are analyzed and compared with one another using the evaluation device.

[0014] According to a further embodiment, a first part of the plurality of conductivity sensors is arranged on the conveying device and a second part of the plurality of conductivity sensors is arranged on other crop processing and / or conveying components of the harvesting machine.

[0015] According to a further embodiment, if at least one of the properties of noise frequency, noise amplitude and base signal of a first signal deviates from at least two second signals, it is concluded that there is an irregularity in the crop flow in the region of the sensor that generates the first signal.

[0016] According to a further embodiment, at least one throughput signal which characterizes a throughput of crop material through the conveying device, such as a driving speed of the harvesting machine or a cutting performance, is taken into account in the analysis of the at least one signal.

[0017] According to a further embodiment, a conductivity of the crop flow of the conveyed crop is measured with a multi-dimensional array of conductivity sensors in the conveying device, wherein in particular a recording of a signal of the conductivity sensor at a first measuring point is compared with the respective signal of the conductivity sensor at one or more second measuring points, and wherein if the recording matches the signal of the conductivity sensor of one of the second measuring points, a direction and / or a speed of the crop flow between the first measuring point and the second measuring point is determined.

[0018] According to a further embodiment, the speed of the crop flow between the first measuring point and the second measuring point is determined by relating a distance between the first measuring point and the second measuring point to a time between the recording at the first measuring point and the detection of the recording at the second measuring point. The harvesting machine with a conveyor device for crop material and with a device for monitoring a crop flow in the conveyor device, with which the object is achieved, has at least one conductivity sensor for generating a signal on the conveyor device that represents a conductivity of a crop flow of the conveyed crop material, wherein the device for monitoring the crop flow has an evaluation device for analyzing the signal.

[0019] According to one embodiment, the conveying device is assigned to a cutting unit of the harvesting machine, wherein the conveying device has a cutting table, and wherein the at least one conductivity sensor is arranged on the cutting table. The conductivity sensor can be arranged, in particular, on a fall-back edge or retaining device of the cutting table.

[0020] According to one embodiment, it is provided that the retaining device has an extension, wherein the extension is arranged approximately parallel to a surface of the cutting table, and wherein the conductivity sensor is arranged on the extension.

[0021] According to one embodiment, a plurality of conductivity sensors are arranged on the cutting table, wherein the conductivity sensors are spaced apart from one another, wherein each of the conductivity sensors generates a signal representing the conductivity of the crop flow, and wherein the evaluation device compares the signals with one another. At least some of the conductivity sensors can be distributed along a width of the cutting unit. At least some of the conductivity sensors can be distributed along a conveying direction of the crop flow through the conveying device.

[0022] Alternatively, the conveying device can be assigned to a separating device of the harvester, for example. At least one conductivity sensor can be arranged in a separating rotor, and at least one further conductivity sensor behind the separating rotor, at the entrance to a straw chopper. If crop material accumulates in the straw chopper, the evaluation device detects this using the method described above via the changed noise behavior of the second conductivity sensor. A crop flow disturbance is detected, and it is advantageous to react before the separating rotor also becomes clogged. Monitoring using conductivity sensors has the advantage of being fast and sensitive.

[0023] The method and the harvesting machine are explained below with reference to the attached drawings, wherein features of the method are also applicable to the harvesting machine and wherein features of the harvesting machine are also applicable to the method.

[0024] Figure 1 shows an embodiment of a harvesting machine according to the invention in a schematic representation.

[0025] Figure 2 shows a conveyor device with a conductivity sensor of the harvesting machine according to Figure 1 in a sectional view;

[0026] Figure 3 shows a recorded signal of a conductivity sensor in a diagram;

[0027] Figures 4 and 5 show diagrams to explain a conductivity measurement of a crop stream in the conveyor device.

[0028] Figure 1 schematically shows an embodiment of a harvesting machine 20 according to the invention, only a part of the harvesting machine 20 being shown. A direction of travel 16 of the harvesting machine 20 is indicated by an arrow. The harvesting machine 20 has a conveying device 21 for crop 18 and a device 22 for monitoring a crop flow in the conveying device 21. At least one conductivity sensor 23 is arranged on the conveying device 21 to generate a signal representing a conductivity of a crop flow of the conveyed crop 18. An evaluation device 24 is provided for analyzing the signal in the device 22 for monitoring the crop flow. The conveying device 21 can be assigned to a cutting unit 6 of the harvesting machine 29, the cutting unit 6 having a cutting table 5 and the at least one conductivity sensor 23 being arranged on the cutting table 5.In the illustrated embodiment, the conveying device 21 comprises a screw conveyor 26. Alternatively, conveyor belts (not shown) can be provided. The conductivity sensor 23 can be arranged on a retaining device 7 of the cutting table 5, which is explained in more detail with reference to Figure 2.

[0029] Figure 2 shows a detail of the conveying device 21 of the harvesting machine 20 according to Figure 1 in a schematic sectional view. The retaining device 7 prevents crop 18 from falling from the cutting table 5 and has the shape of a dam. The retaining device 7 is also referred to as a fall-back edge 7. The cross-section of the retaining device 7 visible in the illustration can be triangular, for example. The retaining device 7 can have an extension 8 parallel to a surface of the cutting table 5, wherein the conductivity sensor 23 can be arranged on the extension 8. A corresponding sensor installation space 9 on the extension 8 of the retaining device 7 is shown schematically. An alternative or additional sensor installation space 9' can be arranged on an end face of the retaining device 7, i.e., at the front in the direction of travel 16 of the harvesting machine 20.Conventional cutting units and Vario cutting units generally provide both installation spaces 9 and 9'. Belt cutting units, depending on their design, only provide installation space 9', since conveyor belts run behind the fall-back edge 7. Due to the crop 18 falling onto the conveyor belts, straw mat formation and congestion on the cutting table 5 are unlikely to occur. Thus, for these cutting units, only monitoring of soil heaving and crop flow blockages on the cutting system is relevant, which can be detected by the conductivity sensors 23 in the installation space 9. A plurality of conductivity sensors 23 can be arranged on the cutting table 5, wherein the conductivity sensors 23 are spaced apart from one another, wherein each of the conductivity sensors transmits a signal 3, 4 (Fig.

[0030] 3), which represents the conductivity of the crop flow, and wherein the evaluation device 24 (Figure 1) compares the signals 3, 4 with each other. At least some of the conductivity sensors 23 can be distributed along a width of the cutting table 5 (orthogonal to the plane of the drawing and the direction of travel 16). At least some of the conductivity sensors 23 can be arranged along a conveying direction 17 (Figure

[0031] 4) of the crop flow through the conveyor device 21, wherein the conveying direction 17 in the illustrated cutting table 5 is orthogonal to the plane of the drawing and the direction of travel 16. The conductivity sensors 23 are arranged on the cutting table 5 below the crop layer 18. The installation space 9 is created when the drop-back edge 7 is extended in the direction of crop flow in the area of ​​the measuring point. The extension 8 creates a plane parallel to the crop layer 18, which provides the installation space 9 for the placement of the conductivity sensor 23. The installation space 9, which is raised relative to the cutting table 5 and arranged parallel, establishes good contact with the crop 18 in the area where the lower stalk halves fall onto the cutting table 5. During normal harvesting, the crop layer 18 is most homogeneous in this area. The drop-back edge 7 is located directly behind the cutting unit 6.If soil pushes over the cutting unit 6, the soil must push further over the fall-back edge 7 to reach the center of the cutting table 5. The front side of the cutting edge 7 is therefore well suited as an installation space 9' for conductivity sensors 23, with which soil accumulations can be detected at an early stage. The installation space 9' is also suitable for measuring straw accumulations, but due to the angled arrangement, the contact of the crop is subject to greater scatter, which increases the noise component. A method for monitoring the crop flow in the conveyor device 21 for the crop 18 is described below. An electrical conductivity of the crop flow of the conveyed crop 18 is measured using the at least one conductivity sensor 23 in the conveyor device 21. The conductivity sensor 23 generates a signal 3, 4 that represents the measured conductivity, which is analyzed using the evaluation device 24.The crop flow is evaluated based on a development of at least one of the following properties of the signal 3, 4: noise frequency, noise amplitude and fundamental signal.

[0032] Figure 3 shows an example of a recorded signal from conductivity sensor 23 in a diagram. Time is plotted on the abscissa 1, while the ordinate represents the signal curve over time. A base level 3 of signal 3, 4 is formed from the moisture content and the quantity of crop. These variables change relatively slowly. A noise component 4 of signal 3, 4 changes relatively quickly due to the high dynamics of sensor contact and the density of crop 18. Depending on the material at the measuring point, the noise amplitude of signal 3, 4 will be higher or lower. Depending on the crop and harvesting situation, the amplitudes of noise component 4 will be significantly higher than the amplitudes of base signal 3. It is to be expected that the rate of change of noise component 4 will be the same as the crop flow velocity.The faster the crop layer 18 flows over one of the conductivity sensors 23, the faster the change in the noise component 4. The frequency of the noise component 4 therefore depends on the crop flow speed. To detect disturbances in the crop flow, for example, the noise frequencies of the segments of the cutting unit 6 can be compared with one another. If the noise frequency drops in one of the segments, e.g. due to the formation of a mat of crop 18, this indicates that the crop flow has come to a standstill in this segment. If accumulations of soil occur at conductivity sensors 23, the basic signal 3 increases significantly with a simultaneous significant decrease in the noise component 4. The reason for this is the higher density, the higher water content and the greater homogeneity of soil compared to straw. This means that accumulations of soil can be detected separately from straw mats.To improve comparability of frequency changes during throughput fluctuations, the forward speed of the harvester 20 can be integrated into the evaluation in addition to the noise frequency comparison. This makes it easier to differentiate frequency changes across a large portion of the cutting unit 6's sections from widespread crop flow disturbances. Furthermore, harvesting situations occur in which the working width of the cutting unit 6 is not fully utilized. In these cases, it is advisable to include the signal from a section control in the evaluation. The section control signal can be provided manually by the driver or by automatic systems such as GPS and optical systems.

[0033] Figures 4 and 5 each show diagrams to explain the conductivity measurement of the crop flow in the conveyor device 21. Within a sensor installation space 9, 9', conductivity sensors 23 can be installed at individual or multiple measuring points. The sensor installation space 9, 9' is schematically shown as a plane spanned by the direction of travel 16 of the harvesting machine 20 and a conveying direction 17 of the crop 18 in the conveyor device 21. Figure 4 shows a sensor installation space 9 or 9' with a single measuring point 10. Figure 5 shows a sensor installation space 9 with multiple measuring points 13, 13', 14, 14'. The measuring points 13 and 13' are located on a front axle 11, viewed in the direction of travel 16. A rear axle 12 is located behind it. The axes 11, 12 can be inclined by an angle 15 relative to the conveying direction 17.On the cutting table 5, the crop flow 18 initially enters in the direction of travel 16 and is then redirected into the conveying direction 17. Assuming that the crop layer 18 does not mix or circulate within the sensor installation space 9, the moisture measurement of the crop layer 18 at one of the measuring points 13, 13', 14, 14' generates a reproducible signal amplitude. If the temporal progression of the signal amplitudes between the measuring points 13, 13', 14, 14' within the sensor installation space 9 is compared, temporally offset correlations in the signal progression 3, 4 of two measuring points result, depending on the deflection of the crop flow. Possible correlation pairings are:

[0034] • Measuring point 13 as the first measuring point and measuring point 14' as the second measuring point;

[0035] • Measuring point 13' as the first measuring point and measuring point 14 as the second measuring point;

[0036] • Measuring point 13 as the first measuring point and measuring point 13' as the second measuring point;

[0037] • Measuring point 14' as the first measuring point and measuring point 14 as the second measuring point;

[0038] • Measuring point 13 as the first measuring point and measuring point 14 as the second measuring point.

[0039] The crop flow velocity can be determined using the known distance and time offset of the correlating signals 3 and 4. This allows for a more accurate and precise comparison between fluctuations in individual sections and the forward speed of the harvester 20. Influences on the alignment of the cutting unit segments, such as throughput fluctuations, are reduced.

[0040] The process can be applied, for example, to an agricultural harvesting attachment, particularly a combine harvester header. The following process steps can be performed:

[0041] - separating the crop 18 from the field,

[0042] - Picking up the crop 18 by the cutting table 5,

[0043] - Diverting the crop 18 from the direction of travel 16 into the conveying direction 17 for further conveying the crop 18 into the harvesting machine 20,

[0044] - Further conveying of the collected crop 18, whereby the conveying direction 17 can then also correspond to the direction of travel 16. The harvesting header is characterized in that at least two conductivity sensors 23 are mounted across the working width of the header, which are networked with the central evaluation device 24. The evaluation device 24 can be configured to detect irregularities and disturbances in the crop flow during the collection, deflection, and further conveying of the crop. The application for monitoring the crop flow in the conveying device 21 assigned to the cutting unit 5 is described here. Additionally or alternatively, it is possible to use the described method to monitor blockages in the harvesting machine 20. This expands the application possibilities of the sensor technology while using the same hardware. For example, a conductivity sensor 23 can be arranged in a separation rotor.Another conductivity sensor 23 can be located behind the separator rotor at the entrance to a straw chopper. If crop material accumulates in the chopper, the evaluation unit detects this via the changed noise behavior of the second conductivity sensor 23. A crop flow disturbance is detected, and action can be taken before the separator rotor also becomes clogged.

[0045] The conductivity sensors 23 can operate according to the principle of electrical conductivity measurement, dielectric conductivity measurement, or capacitive conductivity measurement. The connection between the conductivity sensors 23 and the evaluation device 24 can be established via analog signals or a digital bus system. The evaluation unit 24 can be arranged separately from the conductivity sensors 23 or integrated into one or more of the conductivity sensors 23.

[0046] The procedure for detecting crop flow disturbances in a harvesting header may comprise the following steps:

[0047] - Harvesting 18;

[0048] - guiding the crop flow 18 over the conductivity sensors 23;

[0049] - Generating the conductivity signal 3, 4;

[0050] - combining at least two conductivity signals 3, 4 in the evaluation device 24;

[0051] - Comparison of the signal curves 3, 4 with each other over a period of time and / or comparison of the signal curves 3, 4 with characteristic values;

[0052] - Detection of crop flow disturbances via signal comparison;

[0053] - Generation and output of signals to indicate crop flow disturbances by the evaluation device 24. The output signal of the conductivity sensor 23 depends on the crop density, crop moisture content, and contact between the crop and the conductivity sensor 23, as well as on the density, moisture content, and sensor contact with foreign material (e.g., soil). The material density is influenced by the amount of material and material compression. The moisture content and quantity of the crop are subject to a relatively slow drift. The crop contact with the conductivity sensor 23 and the density of the crop 18 are subject to relatively rapid changes due to fluctuations in the crop layer. Due to these signal influences, the base signal 3 is superimposed by a noise component 4. The rate of change of the noise component 4 changes proportionally with the crop flow rate.The comparison of at least two signals from the conductivity sensors 23 can be performed based on the rate of change of the noise component within a time period. If the rate of change of a conductivity sensor 23 decreases compared to other conductivity sensors 23, a lower crop flow velocity is present at this measuring point. Foreign material such as soil has a higher conductivity and a more constant density. Soil at one of the conductivity sensors 23 generates a higher base signal and a lower noise component compared to the crop. Soil accumulations at a conductivity sensor 23 can be detected by comparing the sensor signal 3, 4 with characteristic values ​​over a time period.The signal evaluation can include a driving speed signal, whereby a change in driving speed has a proportional effect on the rate of change of the noise component 4 and thus can be more accurately determined for crop flow disturbances in all sections. The evaluation can also take into account a throughput-dependent signal, e.g. a cutting performance, in order to compensate for the influence of crop density on the noise component 4 of the conductivity sensors 23. The evaluation can take into account a signal for the number of active sections of a multi-section cutting unit, which is used to exclude sections of the cutting unit that are not in the crop from the evaluation of crop flow disturbances. The section signal can be entered manually by the machine operator or provided automatically by a GPS system or optical field monitoring.The evaluation can take into account a headland signal, which indicates whether the header is in the raised state. This signal is used to perform a zero-point calibration and thus compensate for influences caused by contamination of the conductivity sensors 23. The signal values ​​of the zero-point calibration can be used to evaluate which of the header sections are not in the crop and are excluded from the evaluation.

[0054] Soil build-up in the header trough can occur if the header is not guided correctly over the ground. Rigid headers have sensing arms that detect the soil contour for soil guidance. The transverse slope and height of the header are adjusted using the sensing arms. If there are mounds of earth, waves in the soil contour or furrows in the field that are not detected by the sensing arms, soil can get into the header trough through contact with the ground. Another reason for soil build-up in the header is when the header is harvested close to the ground, for example in laid grain. Torn out plant roots and straw residue can get in front of the header's skids and push up soil. Fingers or ear lifters wrapped in straw can also push up the soil. The pushed-up soil enters the header via a straw mat and settles there.

[0055] Soil accumulation in the header results in reduced friction between the crop and the header trough. Furthermore, a barrier forms for the crop. The crop can no longer be conveyed through the header and accumulates in or in front of the header. At the point of blockage, no new crop can be taken into the header. As the harvester continues to move, more crop is usually flattened and pushed under the header.

[0056] The machine operator often notices soil buildup relatively late. For one thing, the soil buildup occurs under a straw mat and is not immediately visible. For another, it usually occurs in parts of the header that the driver cannot observe all of them at the same time. Blockages caused by soil buildup are often only noticed when no more material is being drawn into the header at that point. To eliminate the crop flow obstruction, harvesting must be stopped and the material removed by hand. The later a soil buildup is noticed, the more material has to be removed, which increases downtime. Crop flow obstructions can also be caused by tough straw or green growth such as burdock wrapping around fingers or ear lifters and blocking the way for further crop into the knife bar or header trough.As a result, additional material is pushed up or flattened by the cutting unit and directed beneath the cutting unit. It is possible that, once a large heap of crop has formed, the blockage will clear itself, and the resulting heap will be fed into the machine. If this process is repeated at the same or a different section of the cutting unit, the harvester will experience an uneven and pulsating crop flow, which can cause blockages in the threshing system. If the blockage does not clear itself, the driver must interrupt harvesting and clear it immediately upon detection.

[0057] Uneven growing conditions in the field can cause plant height and therefore straw length to vary. With conventional or Vario headers, the cutting height or table length must be adjusted to the straw length. In addition, the reel, as a conveying element, must also be adjusted to the straw length. This ensures that the crop falls onto the cutting table at the correct distance from the intake auger, where it is picked up by the auger and transported further. If the straw length becomes shorter, the crop falls onto the cutting table too far in front of the intake auger and is not drawn in by the auger. More and more crop collects on the cutting table and forms a straw mat. When the mat is large enough, the material is pushed to the intake auger either by the reel or by crop in front of the mat.The accumulation and sudden conveying of a buildup of crop creates a pulse-like crop flow that prevents the harvester from working optimally and increases the risk of blockages in the harvester. If the straw is longer, the straw falls onto the intake auger with the middle of the stalk. If the crop is pushed from the front, the stalk stands up on the cutting table and the crop can form a mat. The upright stalks are either drawn into the auger upside down with the cut side first, or they fall sideways and are kinked or conveyed across the auger. This causes an uneven crop flow. In addition, crops drawn in upside down are less effective at threshing in the threshing drum and require a different setting of the threshing components.

[0058] List of reference symbols

[0059] 1 Abscissa, time axis

[0060] 2 Ordinate, signal strength

[0061] 3 Basic signal

[0062] 4 Noise component of the signal

[0063] 5 Cutting table

[0064] 6 cutting unit

[0065] 7 Retaining device, fall-back edge

[0066] 8 Extension of the restraint device

[0067] 9 Sensor installation space on the extension of the restraint device

[0068] 9' 'Sensor installation space on the front side of the restraint device

[0069] 10 Single measuring point

[0070] 11 Front axle

[0071] 12 Rear axle

[0072] 13 measuring point

[0073] 13' measuring point

[0074] 14 measuring point

[0075] 14' measuring point

[0076] 15 Axis angle

[0077] 16 Direction of travel

[0078] 17 Conveying direction

[0079] 18 harvest

[0080] 20 harvester

[0081] 21 Conveyor device

[0082] 22 Device for monitoring a crop flow

[0083] 23 Conductivity sensor

[0084] 24 Evaluation device

[0085] 26 screw conveyor

Claims

Claims 1. Method for monitoring a crop flow in a conveying device (21) for crop (18) of a harvesting machine (1), wherein an electrical conductivity or dielectric conductivity of the crop flow of the conveyed crop is measured with at least one conductivity sensor (23) in the conveying device and a signal (3, 4) representing the measured conductivity is generated and wherein the signal is analyzed with an evaluation device (24), wherein the crop flow is evaluated on the basis of a development of at least one of the following properties of the signal: noise frequency, noise amplitude and background signal.

2. Method according to claim 1, characterized in that a reduction in the noise frequency indicates a reduced flow velocity of the crop flow.

3. Method according to one of the preceding claims, characterized in that a reduction in the noise amplitude with a simultaneous increase in the basic signal indicates a higher water content in the crop flow, wherein, in particular, upon reaching a limit value of the reduction in the noise amplitude and / or the increase in the basic signal, an accumulation of soil in the conveying device (21) is inferred.

4. Method according to one of the preceding claims, characterized in that the conductivity of the harvested crop flow of the conveyed crop is measured with a plurality of mutually spaced conductivity sensors (23). A signal (3, 4) representing the measured conductivity is generated for each conductivity sensor, and the signals are analyzed and compared with each other by the evaluation device (24). A method according to claim 4, characterized in that a first part of the plurality of conductivity sensors (23) is arranged on the conveying device (21) and that a second part of the plurality of conductivity sensors (23) is arranged on other crop-processing and / or conveying components of the harvesting machine (1). A method according to one of the preceding claims 4 or 5, characterized in that if at least one of the properties noise frequency, noise amplitude, and fundamental signal of a first signal deviates from at least two second signals, an irregularity in the crop flow is inferred in the area of ​​the conductivity sensor (23) that generates the first signal.Method according to one of the preceding claims, characterized in that at least one throughput signal, which characterizes a throughput of harvested crop (18) through the conveying device (21 ), such as a driving speed of the harvesting machine (1 ) or a cutting performance, is taken into account in the analysis of the at least one signal (3, 4).A method according to one of the preceding claims, characterized in that the conductivity of the crop flow of the conveyed crop (18) is measured with a multidimensional field of conductivity sensors (23) in the conveying device (21), wherein in particular a recording of a signal from the conductivity sensor at a first measuring point is compared with the respective signal of the conductivity sensor(s) at one or more second measuring points, and wherein, if the recording matches the signal of one of the second measuring points, a direction and / or a speed of the crop flow between the first measuring point and the second measuring point is determined. The method according to claim 8, characterized in that the velocity of the crop flow between the first measuring point and the second measuring point is determined by relating a distance between the first measuring point and the second measuring point to a time between the recording at the first measuring point and the detection of the recording at the second measuring point. The harvesting machine (20) comprises a conveying device (21) for crop (18) and a device (22) for monitoring a crop flow in the conveying device, wherein at least one conductivity sensor (23) for generating a signal (3, 4) representing an electrical or dielectric conductivity of a crop flow of the conveyed crop is arranged on the conveying device, and wherein the device for monitoring the crop flow comprises an evaluation device (24) for analyzing the signal.Harvesting machine according to claim 10, characterized in that the conveying device (21) is associated with a cutting unit (6) of the harvesting machine (20), wherein the conveying device has a cutting table (5) and wherein the at least one conductivity sensor (23) is arranged on the cutting table. Harvesting machine according to claim 11, characterized in that the conductivity sensor (23) is arranged on a retaining device (7) of the cutting table (5). Harvesting machine according to claim 12, characterized in that the retaining device (7) has an extension (8) parallel to a surface of the cutting table (5), wherein the conductivity sensor (23) is arranged on the extension. Harvesting machine according to any one of the preceding claims 10 to 13, characterized in that a plurality of conductivity sensors (23) are arranged on the cutting table (5), wherein the conductivity sensors are oriented relative to one another. are spaced apart, each conductivity sensor generating a signal (3, 4) representing the conductivity of the crop flow, and the evaluation device (24) comparing the signals. Harvesting machine according to claim 14, characterized in that at least a portion of the conductivity sensors (23) are arranged distributed along a width of the cutting table (5) and / or that at least a portion of the conductivity sensors are arranged distributed along a conveying direction (17) of the crop flow through the conveying device (21).

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