Method for controlling the operation of a solenoid valve of an agricultural spreading machine

Abstract

The invention relates to a method for controlling the operation of a solenoid valve (10) used to control the flow rate of a spray liquid in an agricultural spreading machine, comprising the steps of: energizing the solenoid valve (10) according to an energizing specification within the framework of a control process, wherein the energizing of the solenoid valve (10) causes a movement of a valve armature (16) of the solenoid valve (10) arranged in a housing (28) of the solenoid valve (10), detecting the operating state of the solenoid valve (10) by means of an electronic data processing device (26) and adjusting the energizing specification for the solenoid valve (10) taking into account the detected operating state of the solenoid valve (10).

Description

[0001] The invention relates to a method for controlling the operation of a solenoid valve of an agricultural spreading machine according to the preamble of patent claim 1 and to a spreading system for spreading spray liquid onto an agricultural area according to the preamble of patent claim 19.

[0002] Agricultural sprayers typically have several solenoid valves that can be used to control the flow rate of the spray liquid. The flow rate control allows the desired amount of spray liquid to be applied to the agricultural field.

[0003] The application rate of the spray fluid can be roughly adjusted by specifying a specific spray pressure, as the application rate and spray pressure can be correlated. However, studies have shown that this is only approximately true, as the pressure of the spray fluid at the spray nozzle varies over time due to the opening and closing of the solenoid valve, which is not constant. Furthermore, the solenoid valve generates a pressure drop that is dependent on the volume flow.

[0004] To apply the intended amount of spray fluid, the pressure of the spray fluid and the duration of time the solenoid valve is actually open must be known. However, the duration of time the solenoid valve is actually open can only be approximately determined from the current flow to the solenoid valve, since the current flow is based on a theoretical valve behavior that deviates from the actual valve behavior.

[0005] In practice, valves with position feedback are also known, which detect the position directly relative to the valve armature. Such valves often have contactless sensors for direct position detection. The disadvantage of these valves is that the relevant sensor positions are determined by the fact that the valve armature and its entire movement path must be within the sensor's detection range, which significantly limits the selection of the sensor position.

[0006] The object underlying the invention is therefore to enable an improved solenoid valve control in which the operating state of the solenoid valve is taken into account more precisely, without the detection range of a sensor used to detect the operating state having to include the valve armature and its movement path.

[0007] The object is achieved by a method of the type mentioned at the outset, wherein, within the scope of the method according to the invention, a change in state at the solenoid valve or at a line connected to the solenoid valve, caused by the movement of the valve armature and by an interaction between the valve armature and the housing, is detected by a measuring device, and the operating state of the solenoid valve is detected by evaluating the change in state at the solenoid valve or at the line connected to the solenoid valve, detected by a sensor.

[0008] The invention takes advantage of the finding that the opening and closing of the solenoid valve and the associated movements of the valve armature and the interaction between the valve armature and the solenoid valve housing result in characteristic changes in the state of the solenoid valve, which can be detected by a sensor using a measuring device and evaluated to determine the operating state, in particular the opening state, of the solenoid valve. The detection range of the measuring device does not necessarily have to include the valve armature and its movement path, allowing for much greater flexibility in the selection of the sensor position.

[0009] The solenoid valve is preferably controlled by pulse-width modulation, in particular pulse-width frequency modulation. The solenoid valve is controlled, for example, at a frequency between 0 and 50 Hz. The solenoid valve is preferably opened by the magnetic force generated by the current flowing through the solenoid valve coil. The solenoid valve is preferably closed by a return spring of the solenoid valve.

[0010] The line connected to the solenoid valve can be a supply line through which spray fluid can be supplied to the solenoid valve. The supply line can be connected to a valve inlet of the solenoid valve and / or open into the solenoid valve.

[0011] The line connected to the solenoid valve can be a drain line through which spray fluid can be discharged from the solenoid valve. The drain line can be connected to a valve outlet of the solenoid valve and / or originate from the solenoid valve.

[0012] In an advantageous development of the method according to the invention, the measuring device comprises a sensor for detecting the change in state of the solenoid valve, wherein the sensor is arranged outside the housing or inside the housing. The sensor can be in contact with the housing or arranged at a distance from the housing. The sensor can be, for example, a motion sensor, in particular an acceleration sensor, a deformation sensor, a force sensor, or an acoustic sensor.

[0013] Alternatively, the measuring device comprises a sensor for detecting the change in state on the line connected to the solenoid valve, wherein the sensor is arranged outside the line connected to the solenoid valve or inside the line connected to the solenoid valve.

[0014] In a preferred embodiment of the method according to the invention, the measuring device detects a pulse acting on the solenoid valve housing when detecting the change in state of the solenoid valve. The pulse is preferably caused by a movement of the valve armature and is caused by an interaction between the housing and the valve armature. The pulse is preferably generated by the valve armature when it reaches an end position. In the end position, the valve armature can strike an end stop or valve seat. The pulse can be a mechanical pulse or can be a shock or vibration of the housing.

[0015] Alternatively, when detecting the change in state on the line connected to the solenoid valve, the measuring device detects a pulse acting on the line connected to the solenoid valve.

[0016] In a preferred embodiment of the method according to the invention, the measuring device comprises a motion sensor or is designed as a motion sensor. The change in state of the solenoid valve caused by the movement of the valve armature and by an interaction between the valve armature and the housing and detected by a sensor is preferably a change in position or orientation or movement of the solenoid valve or a component, in particular the housing, of the solenoid valve. The operating state of the solenoid valve is preferably detected by evaluating the sensor-detected change in position or orientation or movement of the solenoid valve or the component, in particular the housing, of the solenoid valve. The motion sensor can be arranged on the housing of the solenoid valve. The motion sensor can be arranged outside the housing of the solenoid valve or inside the housing of the solenoid valve.The motion sensor can be located directly on the valve armature. The motion sensor can detect, for example, the movement of the solenoid valve housing or the movement of the valve armature. The motion sensor can be located on or in a fastening element connected to the solenoid valve housing, such as a nut. The change in state of the line connected to the solenoid valve caused by the movement of the valve armature and an interaction between the valve armature and the housing, and detected by the sensor, can be a change in position or orientation or movement of the line connected to the solenoid valve.

[0017] In a further development of the method according to the invention, the motion sensor comprises an acceleration sensor or is designed as an acceleration sensor. The change in state of the solenoid valve caused by the movement of the valve armature and by an interaction between the valve armature and the housing and detected by the sensor is preferably a change in speed or acceleration of the solenoid valve or of a component, in particular the housing, of the solenoid valve. The operating state of the solenoid valve is preferably detected by evaluating the sensor-detected change in speed or acceleration of the solenoid valve or of the component, in particular the housing, of the solenoid valve. The acceleration sensor can be arranged on the housing of the solenoid valve. The acceleration sensor can be arranged outside the housing of the solenoid valve or inside the housing of the solenoid valve.The acceleration sensor can be located directly on the valve armature. The acceleration sensor can, for example, detect the acceleration of the solenoid valve housing or the acceleration of the valve armature. The acceleration sensor can be located on or in a fastening element connected to the solenoid valve housing, such as a nut. The change in state of the line connected to the solenoid valve caused by the movement of the valve armature and an interaction between the valve armature and the housing, and detected by the sensor, can be a change in speed or acceleration of the line connected to the solenoid valve.

[0018] In another preferred embodiment of the method according to the invention, the measuring device comprises a deformation sensor or is designed as a deformation sensor. The change in state of the solenoid valve caused by the movement of the valve armature and by an interaction between the valve armature and the housing and detected by a sensor is a deformation of the solenoid valve or a component, in particular the housing, of the solenoid valve. The operating state of the solenoid valve is preferably detected by evaluating the sensor-detected deformation of the solenoid valve or the component, in particular the housing, of the solenoid valve. The deformation sensor can be arranged on the housing of the solenoid valve. The deformation sensor can be arranged outside the housing of the solenoid valve or inside the housing of the solenoid valve. The deformation sensor can be arranged directly on the valve armature.The deformation sensor can, for example, detect the deformation of the solenoid valve housing or the pre-formation of the valve armature. The deformation sensor can comprise one or more strain gauges or be designed as a strain gauge. The deformation sensor can be arranged on or in a fastening element connected to the solenoid valve housing, for example, a nut. The change in state of the line connected to the solenoid valve caused by the movement of the valve armature and an interaction between the valve armature and the housing, and detected by the sensor, can be a deformation of the line connected to the solenoid valve.

[0019] In a further advantageous embodiment of the method, the measuring device comprises a force transducer or is designed as a force transducer. The change in state of the solenoid valve caused by the movement of the valve armature and by an interaction between the valve armature and the housing and detected by a sensor is preferably a change in the mechanical load on the solenoid valve or a component, in particular the housing, of the solenoid valve, or a force acting on the solenoid valve or a component, in particular the housing, of the solenoid valve. The operating state of the solenoid valve is preferably detected by evaluating the sensor-detected force acting on the solenoid valve or the component, in particular the housing, of the solenoid valve. The force transducer can be arranged on the housing of the solenoid valve.The force transducer can be arranged outside the housing of the solenoid valve or inside the housing of the solenoid valve. The force transducer can be arranged directly on the valve armature. The force transducer can, for example, detect a force acting on the housing of the solenoid valve or on the valve armature. The force transducer can comprise one or more piezo elements or be designed as a piezo element. The force transducer can be arranged on or in a fastening member connected to the housing of the solenoid valve, for example a nut. The change in state on the line connected to the solenoid valve caused by the movement of the valve armature and by an interaction between the valve armature and the housing and detected by a sensor can be a force acting on the line connected to the solenoid valve.

[0020] Furthermore, a method according to the invention is preferred in which the measuring device comprises an acoustic sensor or is designed as an acoustic sensor. The change in state of the solenoid valve caused by the movement of the valve armature and by an interaction between the valve armature and the housing and detected by a sensor is a noise on or in the solenoid valve. The operating state of the solenoid valve is preferably detected by evaluating the sensor-detected noises on or in the solenoid valve. The acoustic sensor can be arranged on the housing of the solenoid valve. The acoustic sensor can be arranged outside the housing of the solenoid valve or in the housing of the solenoid valve. The acoustic sensor can be arranged directly on the valve armature. The acoustic sensor can, for example, detect noises inside and / or outside the housing of the solenoid valve.The acoustic sensor can comprise one or more microphones or be designed as a microphone. The acoustic sensor can be arranged on or in a fastening element connected to the housing of the solenoid valve, for example, a nut. The change in state in the line connected to the solenoid valve caused by the movement of the valve armature and an interaction between the valve armature and the housing, and detected by the sensor, can be a noise on or in the line connected to the solenoid valve.

[0021] In another preferred embodiment of the method according to the invention, the measuring device can also comprise a plurality of different sensors. The measuring device can therefore detect movements, in particular accelerations, of the solenoid valve or a component, in particular the housing of the solenoid valve, deformations of the solenoid valve or a component, in particular the housing of the solenoid valve, and / or noises at or in the solenoid valve. The operating state of the solenoid valve is preferably detected by evaluating the sensor-detected movements, in particular accelerations, of the solenoid valve or a component, in particular the housing of the solenoid valve, by evaluating the sensor-detected deformations of the solenoid valve or a component, in particular the housing of the solenoid valve, and / or by evaluating the sensor-detected noises at or in the solenoid valve.

[0022] In another embodiment of the method according to the invention, the electronic data processing device monitors the temporal progression of the state changes when evaluating the sensor-detected change in state at the solenoid valve or at the line connected to the solenoid valve and, based on characteristic segments of the temporal progression of the state changes, determines the operating state of the solenoid valve. The electronic data processing device preferably monitors the temporal progression of the movements, in particular the accelerations, of the solenoid valve or a part of the solenoid valve and / or the temporal progression of the deformations of the solenoid valve or a part of the solenoid valve and / or the temporal progression of the noises at or in the solenoid valve.

[0023] In another preferred embodiment of the method according to the invention, the solenoid valve whose operating state is detected is a reference solenoid valve. The current specification is uniformly adjusted for a plurality of solenoid valves, taking into account the detected operating state of the reference solenoid valve. Assuming that the solenoid valves have very small manufacturing tolerances or flow rate variations, the operating state can be detected for one solenoid valve, and the resulting current adjustment can then be performed for all solenoid valves.

[0024] In an advantageous development of the method according to the invention, the valve armature of the solenoid valve can be moved between a first end position and a second end position by energizing the solenoid valve, and the detection of the operating state of the solenoid valve by means of the electronic data processing device comprises detecting the end position assumption times at which the valve armature of the solenoid valve assumes the first end position and / or the second end position after a movement. The detection of the end position assumption times is preferably carried out by evaluating the sensor-detected state change of the solenoid valve.

[0025] In a further advantageous development of the method according to the invention, the detection of the end position assumption times comprises the detection of first end position assumption times and / or the detection of the second end position assumption times. At the first end position assumption times, the valve armature of the solenoid valve assumes the first end position after a movement and the solenoid valve is open. At the second end position assumption times, the valve armature of the solenoid valve assumes the second end position after a movement and the solenoid valve is closed. The evaluation of the state change at the solenoid valve thus allows the determination of a time at which the solenoid valve assumes the fully open state and the determination of a time at which the solenoid valve assumes the fully closed state.

[0026] The method according to the invention is further advantageously further developed in that the electronic data processing device determines a current supply specification for the solenoid valve that is matched to the detected end position assumption times in order to adapt the current supply specification and determines an actual value of the opening proportion in the switching cycle of the solenoid valve on the basis of the detected end position assumption times in order to determine the current supply specification that is matched to the detected end position assumption times.The actual value of the opening proportion in the switching cycle of the solenoid valve refers to the ratio between the length of time the solenoid valve is actually open within the switching cycle and the actual cycle duration of the solenoid valve's switching cycle, whereby the actual cycle duration of the switching cycle is made up of the length of time the solenoid valve is actually open within the switching cycle and the length of time the solenoid valve is actually closed within the switching cycle. The actual value of the opening proportion in the switching cycle of the solenoid valve can also be referred to as the actual duty cycle. The actual value of the opening proportion in the switching cycle of the solenoid valve specifies the actual flow rate of the spray liquid through the solenoid valve, particularly in the case of central pressure control, so that the actual application rate of the spray liquid depends on the actual value of the opening proportion in the switching cycle of the solenoid valve.

[0027] In another preferred embodiment of the method according to the invention, the electronic data processing device adapts a control value of the opening portion in the switching cycle of the solenoid valve based on the determined actual value of the opening portion in the switching cycle of the solenoid valve in order to achieve a target value of the opening portion in the switching cycle of the solenoid valve in order to determine the current supply specification coordinated with the detected end position assumption times.The control value of the opening portion in the switching cycle of the solenoid valve refers to the ratio between the time period in which the solenoid valve should theoretically be open within a switching cycle according to the current control and the control cycle duration of the solenoid valve's switching cycle. The control cycle duration of the switching cycle is composed of the time period in which the solenoid valve should theoretically be open within the switching cycle according to the current control and the time period in which the solenoid valve should theoretically be closed within the switching cycle according to the current control. The control value of the opening portion in the switching cycle of the solenoid valve can also be referred to as the control duty cycle.The target value of the opening portion in the switching cycle of the solenoid valve refers to the ratio between the time period during which the solenoid valve should be open within a switching cycle and the target cycle duration of the solenoid valve's switching cycle. The target cycle duration of the switching cycle is composed of the time period during which the solenoid valve should be open within the switching cycle and the time period during which the solenoid valve should be closed within the switching cycle. The target value of the opening portion in the switching cycle of the solenoid valve can also be referred to as the target duty cycle.At the start of the control process, the control value of the opening portion in the switching cycle of the solenoid valve preferably corresponds to the setpoint value of the opening portion in the switching cycle of the solenoid valve. By recording the end position assumption times, it is then determined that the control value of the opening portion in the switching cycle of the solenoid valve does not result in the actual value of the opening portion in the switching cycle of the solenoid valve corresponding to the setpoint value of the opening portion in the switching cycle of the solenoid valve, and an adjustment of the control value of the opening portion in the switching cycle of the solenoid valve is necessary. The setpoint value of the opening portion in the switching cycle of the solenoid valve is preferably assigned to an application rate of spray liquid, so that when a specific application rate of spray liquid is set by the machine operator, a setpoint value of the opening portion in the switching cycle of the solenoid valve is defined and can be retrieved or calculated.

[0028] In an advantageous development of the method according to the invention, the current supply specification determined by the electronic data processing device and matched to the detected end position assumption times comprises a modified pull-in current of the solenoid valve, which leads to a modified pull-in duration of the solenoid valve. The pull-in current leads to the movement of the valve armature from one end position in which the solenoid valve is closed to another end position in which the solenoid valve is open. The pull-in duration refers to the time from the application of the supply voltage until the valve armature reaches the end position in which the solenoid valve is open. The modified pull-in current leads, for example, to a shortened pull-in duration or to a longer pull-in duration. The modified pull-in current can refer to a weaker pull-in current or a stronger pull-in current.

[0029] In an advantageous development of the method according to the invention, the current supply specification determined by the electronic data processing device and adjusted to the detected end-position times comprises a modified holding current supply to the solenoid valve, which leads to a modified holding time of the valve armature. The holding current supply leads to the valve armature being held in the end position in which the solenoid valve is open. The holding time refers to the period of time during which the valve armature is held by a holding current in the end position in which the solenoid valve is open. The modified holding current supply leads, for example, to a shortened holding time or to an extended holding time.

[0030] In another preferred embodiment of the method according to the invention, the current supply specification determined by the electronic data processing device and matched to the detected end position assumption times comprises a modified drop-out current supply to the solenoid valve, which leads to a modified drop-out duration of the valve armature. The drop-out current supply leads to the preferably spring-assisted movement of the valve armature from the end position in which the solenoid valve is open to the end position in which the solenoid valve is closed. The drop-out duration refers to the time period from the application of a negative supply voltage until the valve armature reaches the end position in which the solenoid valve is closed. The modified drop-out current supply leads, for example, to a shortened drop-out duration or to a longer drop-out duration. The modified drop-out current supply can refer to a weakened drop-out current supply or an increased drop-out duration.For example, for a specific current supply specification, it can also be provided that the current supply to the solenoid valve is at least temporarily interrupted during the dropout period or that it is supplied with the supply voltage. The supply voltage can be 12 V or 24 V, for example.

[0031] In another preferred embodiment of the method according to the invention, the current supply specification determined by the electronic data processing device and adjusted to the detected end-position times includes a modified pull-in period of the valve armature, during which the pull-in current is applied to the solenoid valve. Increasing the pull-in period ultimately also increases the release time of the valve armature, since the solenoid valve or valve armature is magnetized more strongly due to the increased pull-in period.

[0032] In an advantageous development of the method according to the invention, the current supply specification determined by the electronic data processing device and adjusted to the detected end-position times results in a changed cycle duration of the switching cycle of the solenoid valve. Alternatively, the current supply specification determined by the electronic data processing device and adjusted to the detected end-position times does not result in a changed cycle duration of the switching cycle of the solenoid valve.

[0033] The object underlying the invention is further achieved by a dispensing system of the type mentioned above, wherein the control device of the dispensing system according to the invention is configured to control the operation of the solenoid valves according to one of the embodiments described above. With regard to the advantages and modifications of the dispensing system according to the invention, reference is therefore made to the advantages and modifications of the method according to the invention.

[0034] Preferred embodiments of the invention are explained and described in more detail below with reference to the accompanying drawings. Fig. 1 a closed solenoid valve of a dispensing system according to the invention in a schematic representation; Fig. 2 that in the Fig. 1 depicted solenoid valve in an open state in a schematic representation; Fig. 3 shows a current intensity curve and an acceleration curve during an operation of a solenoid valve controlled according to the invention in a diagrammatic representation; Fig. 4 shows the method steps carried out within the scope of a method according to the invention when adjusting the current supply specification in a schematic flow diagram; and Fig. 5 a solenoid valve including the supply line of another application system according to the invention in a schematic representation; and Fig. 6 a solenoid valve including drain line of another application system according to the invention in a schematic representation.

[0035] The Fig. 1 and Fig. 2 shows a solenoid valve 10 of a spreading system, which can, for example, be part of a field sprayer. The solenoid valve 10 is used to control the flow rate so that a desired amount of spray liquid, for example, crop protection agent, can be applied to an agricultural field.

[0036] The solenoid valve 10 has a valve inlet 12 and a valve outlet 14. The spray liquid to be dispensed enters the solenoid valve 10 via the valve inlet 12. The spray liquid to be dispensed can be discharged from the solenoid valve 10 via the valve outlet 14. The discharged spray liquid is fed to a spray nozzle via line section 28.

[0037] The fluid connection between the valve inlet 12 and the valve outlet 14 can be blocked and released via a valve armature 16. The solenoid valve 10 shown is a normally closed valve, whereby the valve armature 16 can be raised by energizing the solenoid valve 10, thus fluidly connecting the valve inlet 12 to the valve outlet 14.

[0038] The solenoid valve 10 is connected to a control device 24 via a power supply line 22. The control device 24 comprises an electronic data processing device 26 and serves to regulate the operation of the solenoid valve 10. The coil 18 of the solenoid valve 10 is energized via the power supply line 22. Energizing the coil 18 creates a magnetic field that causes the valve armature 16 to move upwards. The valve armature 16 is coupled to a return spring 20, which applies a closing force to the valve armature 16. The return spring 20 moves the valve armature 16 back into the closed position if the coil 18 is not energized or is insufficiently energized.

[0039] The solenoid valve 10 has a housing 28. A measuring device 30 is arranged on the housing 28. The measuring device 30 uses sensors to detect a change in state of the solenoid valve 10 caused by the movement of the valve armature 16 and an interaction between the valve armature 16 and the housing 28, so that the operating state of the solenoid valve 10 can be determined by evaluating the sensor-detected change in state of the solenoid valve 10.

[0040] The measuring device 30 is designed as a motion sensor. The change in state of the solenoid valve 10 caused by the movement of the valve armature 16 and the interaction between the valve armature 16 and the housing 28, and detected by the sensor, is therefore a movement of the housing 28 of the solenoid valve 10. In the illustrated embodiment, the motion sensor is designed as an acceleration sensor. The change in state of the solenoid valve 10 caused by the movement of the valve armature 16 and the interaction between the valve armature 18 and the housing 28, and detected by the sensor, is therefore the acceleration of the housing 28 of the solenoid valve 10.

[0041] In the Fig. 3, the current I flowing through the solenoid valve 10 is plotted against time t. Furthermore, the acceleration a of the housing 28 of the solenoid valve 10 is plotted against time t.

[0042] The current flow Iv shows three characteristic time periods, namely the duration t An , the holding period t H and the decay time t Ab . During the tightening period t An A supply voltage is applied to the solenoid valve 10, so that the applied current increases in a ramp-like manner, whereby the valve armature 16 is moved from the end position in which the valve armature 16 is in the closed state of the solenoid valve 10, to the end position in which the valve armature 16 is in the open state of the solenoid valve 10. The end position times t E1 are therefore within the operating time t An .

[0043] In order to keep the solenoid valve 10 in the open state, during the holding time t HThe current is impressed into the coil 18 of the solenoid valve 10 via a pulse-width modulated voltage signal. As a result, the impressed current decreases over time, whereby the generated magnetic field remains constant throughout the entire holding time t H is always strong enough to keep the valve armature 16 in the open position.

[0044] To close the solenoid valve 10, at the beginning of the drop period t Ab A negative supply voltage is applied, which promotes the rapid dissipation of the magnetic field holding the valve armature 16 and thus the spring-assisted movement of the valve armature 16. The decay time t Ab ends with a final position taking time t E2 in which the valve armature 16 has reached the end position in which the solenoid valve 10 is closed.

[0045] This results in a time period t o , in which the solenoid valve 10 is open, and a time period t g, in which the solenoid valve 10 is closed. This results in an actual cycle time t Z of the switching cycle of the solenoid valve 10, whereby the actual cycle time t Z of the switching cycle from the time period t o , in which the solenoid valve 10 is actually opened within the switching cycle, and the time period t g , in which the solenoid valve 10 is actually closed within the switching cycle.

[0046] To determine the final position times t E1 , t E2 the electronic data processing device 26 monitors the sensor-detected acceleration a of the housing 28 of the solenoid valve 10 and, based on characteristic sections of the acceleration curve over time, detects a v the final position times t E1 , t E2. The measuring device 30 detects the acceleration a of the housing 28 of the solenoid valve 10 at such a high frequency that characteristic sections in the temporal acceleration curve a V can be recognized. The characteristic sections in the temporal acceleration curve a V , from which the final position times t E1 , t E2 can be derived are characteristic curve maxima and curve minima.

[0047] The electronic data processing device 26 calculates from the time period t o , the time period t g and the cycle duration t Z an actual value for the opening portion in the switching cycle of the solenoid valve 10. The actual value of the opening portion in the switching cycle of the solenoid valve 10 concerns the relationship between the time period t o , in which the solenoid valve 10 is actually opened within the switching cycle, and the actual cycle time tZ of the switching cycle of the solenoid valve 10. The actual value of the opening portion in the switching cycle of the solenoid valve 10 can also be referred to as the actual duty cycle.

[0048] The electronic data processing device 26 determines, in order to adapt the current supply specification for the solenoid valve 10, a time t E1 , t E2coordinated current supply specification for the solenoid valve 10, wherein the actual value of the opening portion in the switching cycle of the solenoid valve 10 is calculated to determine this current supply specification for the solenoid valve 10. If the actual value of the opening portion in the switching cycle of the solenoid valve 10 deviates from a target value of the opening portion in the switching cycle of the solenoid valve 10, the electronic data processing device adjusts a control value of the opening portion in the switching cycle of the solenoid valve 10.The control value of the opening portion in the switching cycle of the solenoid valve 10 relates to the ratio between the time period in which the solenoid valve 10 should theoretically be open within a switching cycle according to the current control and a control cycle duration of the switching cycle of the solenoid valve 10. The control cycle duration of the switching cycle is composed of the time period in which the solenoid valve 10 should theoretically be open within the switching cycle according to the current control and the time period in which the solenoid valve 10 should theoretically be closed within the switching cycle according to the current control. The control value of the opening portion in the switching cycle of the solenoid valve 10 can also be referred to as the control duty cycle.The target value of the opening portion in the switching cycle of the solenoid valve 10 relates to the ratio between the time period during which the solenoid valve 10 should be open within the switching cycle and a target cycle duration of the switching cycle of the solenoid valve 10. The target cycle duration of the switching cycle is composed of the time period during which the solenoid valve 10 should be open within the switching cycle and the time period during which the solenoid valve 10 should be closed within the switching cycle. The target value of the opening portion in the switching cycle of the solenoid valve 10 can also be referred to as the target duty cycle.

[0049] The Fig. 4 shows an example of a process flow when adjusting the current supply specification.

[0050] In method step 100, a target duty cycle of the solenoid valve 10 is first defined. The target duty cycle describes the target value of the opening portion in the switching cycle of the solenoid valve 10 and thus relates to the relationship between the period of time during which the solenoid valve 10 should actually be open within a switching cycle and the target cycle duration of the solenoid valve's switching cycle. Since the application rate of the spray liquid is directly dependent on the duty cycle of the solenoid valve 10, the target duty cycle is specified, for example, by the intended application rate of spray liquid. The target duty cycle can be, for example, 60% or 0.6. The solenoid valve 10 should therefore be open for 60% of the switching cycles.

[0051] At the beginning of a control process, a control duty cycle is set, which initially corresponds to the target duty cycle. The control duty cycle is a control value of the opening portion in the switching cycle of solenoid valve 10 and thus relates to the ratio between the time period in which the solenoid valve should theoretically be open within a switching cycle according to the current control, and a control cycle duration of the switching cycle of the solenoid valve. Therefore, in method step 102, a control duty cycle is set that corresponds to the target duty cycle. In the present example, this would be 60% or 0.6.

[0052] In process step 104, the end position times t E1 , t E2of the solenoid valve 10 is recorded and evaluated to determine the actual duty cycle. The actual duty cycle describes the actual opening portion of the switching cycle of the solenoid valve 10 and thus relates to the relationship between the time period in which the solenoid valve 10 is actually open within a switching cycle and the actual cycle duration of the switching cycle of the solenoid valve. To determine the end position times t E1 , t E2 the electronic data processing device 26 monitors the sensor-detected movements of the housing 28 of the solenoid valve 10 and, based on characteristic sections in the temporal acceleration profile a V the final position times t E1 , t E2. For this purpose, the measuring device 30 records the movements of the housing 28 of the solenoid valve 10 at such a high frequency that characteristic sections of the movement can be recognized. The characteristic sections from which the end position times t E1 , t E2 can be derived, can be local maximum values ​​or minimum values. In other embodiments, the characteristic curve sections can also be formed by characteristic curve gradients, both rising and falling. The characteristic curve sections can also refer to specific curve profiles in the temporal movement or acceleration profile. The value obtained over the end position times t E1 , t E2 The actual duty cycle determined can, for example, be 64% or 0.64.

[0053] In the subsequent method step 106, the recorded actual duty cycle is then compared with the target duty cycle. If the actual duty cycle matches the target duty cycle or is at least within a tolerance range, the intended amount of spray liquid is already being applied and an adjustment of the current supply for the solenoid valve 10 is not necessary. In this case, the current actual duty cycle would be determined again in method step 104. If the actual duty cycle deviates from the target duty cycle or is outside a tolerance range, the intended amount of spray liquid is not applied and an adjustment of the current supply for the solenoid valve 10 is necessary. In the present example, the actual duty cycle deviates by 64% or 0.64 from the target duty cycle of 60% or 0.6.

[0054] In method step 108, the control duty cycle, i.e., the control value of the opening portion in the switching cycle of solenoid valve 10, is then adjusted to achieve a change in the actual duty cycle. The adjustment is determined by the data processing device 26 based on the difference between the actual duty cycle and the target duty cycle, as well as an internally stored calculation routine. In the present example, the control duty cycle is set to 56% or 0.56.

[0055] In the method steps 110a, 110b and 110c, of which one, two or all can be carried out, the electronic data processing device 26 then generates a time interval t E1 , t E2 coordinated current supply specification is determined.

[0056] In method step 110a, the electronic data processing device 26 generates a time interval t E1 , tE2 coordinated current specification is determined, which has a changed pull-in current of the solenoid valve 10, which leads to an adapted pull-in time t which changes the actual duty cycle An of the valve armature 16.

[0057] In method step 110b, the electronic data processing device 26 generates a time interval t E1 , t E2 coordinated current specification is determined, which has a changed holding current of the solenoid valve 10, which leads to an adjusted holding time t which changes the actual duty cycle H of the valve armature 16.

[0058] In method step 110c, the electronic data processing device 26 generates a time interval t E1 , t E2coordinated current supply specification is determined, which has a changed drop-out current supply of the solenoid valve 10, which leads to an adapted drop-out time t which changes the actual duty cycle Ab of the valve armature 16.

[0059] Subsequently, in method step 104, the current actual duty cycle is determined again and in method step 106 it is checked whether the adjustment of the control duty cycle has resulted in the actual duty cycle now corresponding to the target duty cycle.

[0060] The Fig. 5 shows a solenoid valve 10 including supply line 32a. The measuring device 30 is arranged on the supply line 32a. A measuring device 30 senses a change in state on the supply line 32a caused by the movement of the valve armature 16 and an interaction between the valve armature 16 and the housing 28. The operating state of the solenoid valve 10 is sensed by evaluating the sensor-detected change in state on the supply line 32a.

[0061] The Fig.6 shows a solenoid valve 10 including a drain line 32b. The measuring device 30 is arranged on the drain line 32b. A measuring device 30 senses a change in state on the drain line 32b caused by the movement of the valve armature 16 and an interaction between the valve armature 16 and the housing 28. The operating state of the solenoid valve 10 is sensed by evaluating the sensor-detected change in state on the drain line 32b. List of reference symbols 10 Solenoid valve 12 valve inlet 14 Valve outlet 16 valve anchors 18 coil 20 return spring 22 Power supply line 24 Control device 26 Data processing facility 28 housings 30 measuring device 32a, 32b lines a acceleration a V Acceleration curve I current I v Current strength curve t Ab Waste duration t An Tightening time t E1 Final position times t E2 Final position times t o Duration t H Holding period t o Duration t Z Cycle duration U voltage U V Voltage curve

Claims

[1] Method for controlling the operation of a solenoid valve (10) of an agricultural spreading machine used to control the flow rate of a spray liquid, comprising the steps: - energizing the solenoid valve (10) according to an energization specification as part of a control process, wherein energizing the solenoid valve (10) causes a movement of a valve armature (16) of the solenoid valve (10) arranged in a housing (28) of the solenoid valve (10); - detecting the operating state of the solenoid valve (10) by means of an electronic data processing device (26); and - adjusting the current supply specification for the solenoid valve (10) taking into account the detected operating state of the solenoid valve (10); characterized bythat a change in state at the solenoid valve (10) or at a line (32a, 32b) connected to the solenoid valve (10) caused by the movement of the valve armature (16) and by an interaction between the valve armature (16) and the housing (28) is detected by a measuring device (30), and the detection of the operating state of the solenoid valve (10) takes place by evaluating the sensor-detected change in state at the solenoid valve (10) or at the line (32a, 32b) connected to the solenoid valve (10). [2] Method according to claim 1, characterized by that the measuring device (30) - a sensor for detecting the change in state of the solenoid valve (10), wherein the sensor is arranged outside the housing (28) or inside the housing (28), or - a sensor for detecting the change in state on the line (32a, 32b) connected to the solenoid valve (10), wherein the sensor is arranged outside the line (32a, 32b) connected to the solenoid valve (10) or inside the line (32a, 32b) connected to the solenoid valve (10). [3] Method according to claim 1 or 2, characterized by that the measuring device (30) - when detecting the change in state of the solenoid valve (10), a pulse acting on the housing (28) of the solenoid valve (10) is detected; or - when detecting the change in state on the line (32a, 32b) connected to the solenoid valve (10), a pulse acting on the line (32a, 32b) connected to the solenoid valve (10) is detected. [4] Method according to one of the preceding claims, characterized by that the measuring device (30) comprises a motion sensor or is designed as a motion sensor and - the change in state of the solenoid valve (10) caused by the movement of the valve armature (16) and caused by an interaction between the valve armature (16) and the housing (28) and detected by a sensor is a change in position or orientation or movement of the solenoid valve (10) or a component, in particular of the housing (28), of the solenoid valve (10); or - the change in state of the line (32a, 32b) connected to the solenoid valve (10) caused by the movement of the valve armature (16) and caused by an interaction between the valve armature (16) and the housing (28) and detected by a sensor is a change in position or orientation or movement of the line (32a, 32b) connected to the solenoid valve (10). [5] Method according to one of the preceding claims, characterized by that the motion sensor comprises an acceleration sensor or is designed as an acceleration sensor and - the change in state of the solenoid valve (10) caused by the movement of the valve armature (16) and caused by an interaction between the valve armature (16) and the housing (28) and detected by a sensor is a change in speed or acceleration of the solenoid valve (10) or a component, in particular of the housing (28), of the solenoid valve (10); or - the change in state on the line (32a, 32b) connected to the solenoid valve (10) caused by the movement of the valve armature (16) and by an interaction between the valve armature (16) and the housing (28) and detected by a sensor is a change in speed or acceleration of the line (32a, 32b) connected to the solenoid valve (10). [6] Method according to one of the preceding claims, characterized by that the measuring device (30) comprises a deformation sensor or is designed as a deformation sensor and - the change in state of the solenoid valve (10) caused by the movement of the valve armature (16) and caused by an interaction between the valve armature (16) and the housing (28) and detected by a sensor is a deformation of the solenoid valve (10) or a component, in particular of the housing (28), of the solenoid valve (10); or - the change in state of the line (32a, 32b) connected to the solenoid valve (10) caused by the movement of the valve armature (16) and by an interaction between the valve armature (16) and the housing (28) and detected by a sensor is a deformation of the line (32a, 32b) connected to the solenoid valve (10). [7] Method according to one of the preceding claims, characterized by that the measuring device (30) comprises a force transducer or is designed as a force transducer and - the change in state of the solenoid valve (10) caused by the movement of the valve armature (16) and caused by an interaction between the valve armature (16) and the housing (28) and detected by a sensor is a force acting on the solenoid valve (10) or a component, in particular the housing (28), of the solenoid valve (10); or - the change in state on the line (32a, 32b) connected to the solenoid valve (10) caused by the movement of the valve armature (16) and by an interaction between the valve armature (16) and the housing (28) and detected by a sensor is a force acting on the line (32a, 32b) connected to the solenoid valve (10). [8] Method according to one of the preceding claims, characterized by that the measuring device (30) comprises an acoustic sensor or is designed as an acoustic sensor and - the change in state of the solenoid valve (10) caused by the movement of the valve armature (16) and by an interaction between the valve armature (16) and the housing (28) and detected by a sensor is a noise on or in the solenoid valve (10); or - the change in state on the line (32a, 32b) connected to the solenoid valve (10) caused by the movement of the valve armature (16) and by an interaction between the valve armature (16) and the housing (28) and detected by a sensor is a noise on or in the line (32a, 32b) connected to the solenoid valve (10). [9] Method according to one of the preceding claims, characterized bythat the electronic data processing device (26) monitors the temporal progression of the state changes when evaluating the sensor-detected state change on the solenoid valve (10) or on the line (32a, 32b) connected to the solenoid valve (10) and records the operating state of the solenoid valve (10) on the basis of characteristic progression sections in the temporal progression of the state changes. [10] Method according to one of the preceding claims, characterized by that the solenoid valve (10) whose operating state is detected is a reference solenoid valve and the current supply specification for a plurality of solenoid valves is uniformly adapted taking into account the detected operating state of the reference solenoid valve. [11] Method according to one of the preceding claims, characterized bythat the valve armature (16) of the solenoid valve (10) is movable between a first end position and a second end position by energizing the solenoid valve (10), and the detection of the operating state of the solenoid valve (10) by means of the electronic data processing device (26) enables the detection of end position times (t E1 , t E2 ), to which the valve armature (16) of the solenoid valve (10) assumes the first end position and / or the second end position after a movement. [12] Method according to claim 11, characterized by that the electronic data processing device (26) for adapting the current supply specification generates a time constant based on the detected end position times (t E1 , t E2 ) coordinated current supply for the solenoid valve (10) is determined and used to determine the recorded end position times (t E1 , t E2 ) coordinated current supply specification based on the recorded end position times (t E1 , tE2 ) determines an actual value of the opening portion in the switching cycle of the solenoid valve (10). [13] Method according to claim 12, characterized by that the electronic data processing device (26) for determining the recorded final position times (t E1 , t E2 ) adjusted current supply specification, a control value of the opening portion in the switching cycle of the solenoid valve (10) is adjusted on the basis of the determined actual value of the opening portion in the switching cycle of the solenoid valve (10) in order to achieve a target value of the opening portion in the switching cycle of the solenoid valve (10). [14] Method according to claim 12 or 13, characterized by that the time of taking the final position (t E1 , t E2 ) coordinated current supply specification comprises a changed pull-in current of the solenoid valve (10), which leads to a changed pull-in time (t An) of the valve armature (16). [15] Method according to one of claims 12 to 14, characterized by that the time of taking the final position (t E1 , t E2 ) comprises a changed holding current of the solenoid valve (10), which leads to a changed holding time (t H ) of the valve armature (16). [16] Method according to one of claims 12 to 15, characterized by that the time of taking the final position (t E1 , t E2 ) coordinated current supply specification comprises a changed drop current supply of the solenoid valve (10), which leads to a changed drop duration (t Ab ) of the valve armature (16). [17] Method according to one of claims 12 to 16, characterized bythat the time of taking the final position (t E1 , t E2 ) adjusted current specification a changed operating time (t An ) of the valve armature (16), during which the pull-in current of the solenoid valve (10) takes place. [18] Method according to one of claims 12 to 17, characterized by that the time of taking the final position (t E1 , t E2 ) coordinated current supply specification leads to a changed cycle duration of the switching cycle of the solenoid valve (10). [19] Application system for applying spray liquid to an agricultural area, with - a plurality of solenoid valves (10) used for flow rate control, each having a valve armature (16) arranged in a housing (28) of the solenoid valve (10), - a control device (24) by means of which the operation of the solenoid valves (10) can be controlled, and - a measuring device (30) which is designed to sensorically detect a change in state at the solenoid valve (10) or at a line (32a, 32b) connected to the solenoid valve (10) caused by the movement of the valve armature (16) and by an interaction between the valve armature (16) and the housing (28); characterized by that the control device (24) is designed to control the operation of the solenoid valves (10) according to one of claims 1 to 18.

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