Patent Publication Number: US-2013234057-A1

Title: Valve For An Agricultural Spraying Machine

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation of international patent application PCT/EP2011/067831, filed on Oct. 12, 2011 designating the U.S., which international patent application has been published in German language and claims priority from German patent application DE 10 2010 051 580.9, filed on Nov. 8, 2010. The entire contents of these priority applications are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The disclosure relates to a valve for an agricultural spraying machine, said valve being able to control a flow rate of a spray medium in accordance with a valve position and comprising an electrically operated actuator for setting the valve position. 
     In agriculture, the reliability of individual apparatus components plays a major role. During operation, for example in a field, all apparatus components are subjected to strong mechanical vibrations. The apparatus components have to be robust with respect to such mechanical vibrations in order to ensure a long service life. This is necessary since repairs either cannot be carried out at the site of operation of the agricultural machines or can only be carried out there with difficulty. In cases of serious faults, the operation therefore often has to be stopped completely for repair purposes. 
     For the spraying of fields with a spray medium, spraying machines are used, which have a multiplicity of spray nozzles. The respective spray medium is dispensed over the field by means of the spray nozzles. For example, the spray medium may be a pesticide or fertilizer. The spray nozzles are typically arranged on a boom of the spraying machine. This boom is very wide, and therefore the greatest possible area can be sprayed in a short period of time. As a result, a high number of spray nozzles are required simultaneously and are arranged uniformly along the boom. The spraying machine comprises both the boom and an agricultural machine. The boom is fastened directly to the agricultural machine or is located on a trailer, which is pulled by the agricultural machine. 
     The valves are typically operated by means of pneumatic or hydraulic controllers. These provide a high level of robustness with respect to mechanical vibrations. One disadvantage is the need for supply lines, which, compared to electrical lines, require a very large amount of installation space. In addition, a device for generating pressure and also a pressure accumulator have to be provided, which require further installation space and generate additional costs during production of the spraying machine. Furthermore, control on a pneumatic and hydraulic basis is relatively slow compared to electrical actuators, and therefore the versatility of the activation is limited compared to electrical actuators. A further disadvantage is that the spray nozzles can only be controlled in large groups, since individual activation can only be implemented in a very complex manner. 
     Due to the use of GPS systems in agricultural machinery, the spray nozzles can be controlled automatically. A method of this type is known for example from EP 0 761 084 A1. An on-board computer of the spraying machine detects and stores the positions of the spraying machine during operation. At the same time, the amount of spray medium and the area of ground in which it is distributed are detected. If, during operation, the boom projects again into an area of ground that has already been sprayed, the on-board computer then automatically switches off the corresponding spray nozzles. An area of ground is thus prevented from receiving too much spray medium. 
     An option for electrically controlling the spray nozzles on the boom provides the advantage here that said nozzles can be controlled very quickly. It is thus possible to set very quickly along the boom whether the spray medium is dispensed, and, if so, to what extent. Areas of land that have already been sprayed are thus prevented from being sprayed again in a very efficient and accurate manner when the spraying machine turns or avoids an obstacle. In addition, valves with electrical actuators can be activated individually in a very simple manner, thus resulting in a very accurate control. 
     A nozzle module that is fastened to a boom is disclosed in DE 10 2004 011 737 A1. The nozzle module has a supply line, which leads to a controllable valve. The valve is connected on the output side to one or more spray nozzles. To this end, the valve can be pneumatically or electrically activated in order to convey the spray medium from a supply line to the spray nozzle, and to then spray said spray medium there. 
     U.S. Pat. No. 5,772,114 mentions an electrical system for activating spray nozzles. However, it is also described that the pneumatic system would be preferable since air supply lines are more robust than electrical lines. 
     EP 2 153 710 A2 describes a use of electrically activatable control valves in a field sprayer. These are used to control the flow rate to the spray nozzles in accordance with the speed of the agricultural machine. To this end, a few electrical control valves are used, which each control a respective sub-breadth of the boom as a whole, comprising a multiplicity of spray nozzles. 
     In order to achieve accurate activation of the spray nozzles, a correspondingly large number of individually activatable valves are required. The use of a large number of valves with electrical actuators leads to a very large power demand. This is particularly the case if all valves are to be activated at the same time. In the case of wide booms with a particularly large number of valves, this may lead to an overload of the on-board system in the agricultural machine. 
     U.S. Pat. No. 4,813,604 indicates this problem. It is proposed to initially activate only one half of the valves at the same time and to then activate the second half. However, this has the disadvantage that the valves can only be activated in accordance with the current state of control of the valves. In other words, the possibilities for activating the valves are limited and the speed of the activation is thus reduced. 
     A further aspect with the use of valves with electrical actuators is that the valves are to be designed typically as opening valves, that is to say the valves are automatically closed without assistance. In the event of a fault, an uncontrollable leakage of the spray medium can thus be reliably prevented. 
     The German utility model DE 1 813 813 U and German patent application DE 10 2004 011 737 A1 therefore propose valves that are then automatically closed by means of a compression spring when not opened by an external application of energy. However, the use of such a spring in an electrically operated valve leads to the fact that additional electrical energy has to be applied when opening the valves in order to overcome the force of the spring. 
     SUMMARY OF THE INVENTION 
     It is therefore an object to specify a valve that ensures a robust and reliable use in the agricultural field, wherein the valve is to be controllable very quickly. 
     According to a first aspect, there is provided a valve for an agricultural spraying machine, said valve being configured to control a flow rate of a spray medium in accordance with a valve position, wherein the valve comprises: 
     an electric motor for setting the valve position; an electrical energy store, which provides electrical energy for operating the electric motor; 
     a control and evaluation unit, which is configured to charge the electrical energy store and to control the electric motor; 
     a power source for supplying the control and evaluation unit and the motor with electrical current; and a microcontroller that detects a motor current that is supplied to the electric motor; 
     wherein the control and evaluation unit is configured to control the electric motor to generate a periodic movement with a defined number of movement strokes and a defined amplitude if it is identified on the basis of the detected motor current that the valve is soiled or gridlocked, and 
     wherein the electrical energy store has a capacity that ensures at least two such movement strokes for shaking free the valve if it is soiled or gridlocked. 
     According to a further aspect, there is provided a valve for an agricultural spraying machine, said valve being configured to control a flow rate of a spray medium in accordance with a valve position, wherein the valve comprises: 
     an electrically operated actuator for setting the valve position; an electrical energy store, which provides electrical energy for operating the actuator; 
     a control and evaluation unit, which is configured to charge the electrical energy store and to control the actuator; 
     wherein the electrical energy store has a capacity that ensures at least two switching operations of the valve, and wherein the control and evaluation unit is configured to control the actuator to generate a periodic movement with a defined number of movement strokes and a defined amplitude. 
     According to a still further aspect, there is provided a valve for an agricultural spraying machine, said valve being configured to control a flow rate of a spray medium in accordance with a valve position, wherein the valve comprises: 
     an electrically operated actuator for setting the valve position; an electrical energy store, which provides electrical energy for operating the actuator; 
     a control and evaluation unit, which is configured to charge the electrical energy store and to control the actuator; 
     wherein the control and evaluation unit is configured to charge the electrical energy store over a charging period that is considerably longer than a discharging period upon an activation of the actuator. 
     The new valve therefore has an energy store, which provides the electrical energy, in order to actuate the actuator. Energy from the electrical energy store is thus provided immediately for the actuator as required and does not have to be drawn directly from the power supply. Peak current values in the power supply can therefore be prevented. Once the valve has been activated, the energy store is recharged from the power supply, preferably over a charging period that is considerably longer than the discharging period upon activation of the actuator. For this purpose, a much lower current can be drawn from the power supply than would be required with direct operation of the valve via the power supply. The magnitude of the necessary current consumption for each energy store for the charging process can additionally be adapted in accordance with an available charging time. The maximum possible charging time is given from the moment at which the valve has to be ready for use once again. The minimum necessary charging time is determined by the physical properties of the energy store. On the whole, the current consumption for a multiplicity of the presented valves on a boom can thus be minimized. 
     In a refinement, the current consumption can be set to a value less than or equal to 0.5 amps, preferably less than or equal to 0.2 amps, and more preferably to less than or equal to 0.1 amps. The on-board power supply system of the spraying machine can thus be used as a power supply, without any risk of overload. Furthermore, the use of the energy store provides the advantage that an emergency shutdown is ensured at any moment during operation of the valve. 
     This results in the advantages that the activation, as a whole, of the valves is very robust with respect to external influences since a readiness for operation of the individual valves irrespective of the momentary state of the power supply is provided and ensured. In addition, the valves can be switched very quickly and reliably when the energy store is charged. 
     The capacity of the energy store is such that the actuator can perform at least one complete switching process without an external energy feed. The energy store preferable has a capacity that ensures at least two and preferably at least three switching processes. A particularly robust operation is thus ensured, since a switching process can be repeated without recharging. This is advantageous, for example in order to shake free a soiled and stiff valve. 
     In a refinement, two or more energy stores are used in order to ensure the readiness for operation of the valve. As a result, the capacity of the individual energy stores may be lower compared to a single energy store, which has an advantageous effect on the installation space requirements. In addition, the redundancy ensures greater reliability. 
     Here, an agricultural spraying machine is understood in particular to mean an agricultural machine that has a boom with a multiplicity of spray nozzles. The boom is preferably arranged directly on the agricultural machine or is arranged on a trailer, which is pulled by the agricultural machine. 
     The boom preferably has a multiplicity of nozzle modules. Each nozzle module comprises a spray nozzle holder, a valve and a spray nozzle. The spray module may also have a group of spray nozzles, which are controlled jointly by the valve. Here, the spray nozzles of a common nozzle module spray a common ground area, at least in part, with the spray medium. The use of the nozzle module has the advantage of a very compact design. For a repair or maintenance, the entire nozzle module can be replaced very quickly and easily. 
     A multiplicity of nozzle modules and therefore of valves may be used along the boom and can be controlled individually very easily and quickly by the electrical actuator. A particularly accurate metering of the spray medium over a field is thus enabled, since not only can entire portions of spray nozzles of the boom be switched on or switched off, but the nozzle modules along the boom can be controlled with the accuracy of the spacing of the nozzle modules. 
     In a refinement, the energy store is an electrical capacitor. 
     The energy store may be designed as an electronic component in the form of a capacitor. The advantage in this case is that capacitors only require a small amount of installation space and, at the same time, provide a high storage capacity. Furthermore, capacitors are available in a wide range of embodiments for industrial purposes, which leads to a cost-effective design of the valve. In addition, capacitors are very robust with respect to environmental influences, which increases the robustness of the valve with respect to environmental influences. Furthermore, capacitors provide the advantage that they can be charged very quickly, for example compared to chemical energy stores. On the whole, a very robust, compact and cost-effective design of the valve can thus be implemented by the use of capacitors as energy stores. 
     In a further refinement, the valve has a switchable electrical bypass, which can connect a power supply to the actuator. 
     The valve may include a switchable, electrical bypass line (the bypass), which bypasses the energy store. By connecting the bypass, the actuator can be connected directly to the power supply. At the same time, the energy store is preferably isolated from the power supply. The power supply can thus operate the actuator, without simultaneously having to charge the energy store. The current consumption of the valve is thus limited to a necessary minimum. Furthermore, it is advantageous for protection of the energy store if the actuator is simultaneously disconnected from the energy store. 
     The bypass is connected in particular when the energy store is not sufficiently charged or has a defect. The bypass is preferably controlled by a switchable diode. 
     In a further refinement, the actuator is an electric motor. 
     The use of the electric motor has the advantage that it can place the valve in a specific position and can then hold it in this position. It is particularly advantageous that the electric motor does not require any additional current as it holds this position, as is the case for example with a solenoid valve with a return spring. 
     In addition, a particularly accurate activation and therefore particularly accurate metering of the dispensed volume of spray medium can be achieved as a result of the use of the electric motor. The electric motor may be designed as a stepper motor. These have the advantage that they convert control signals particularly reliably, quickly and very accurately. 
     In a further refinement, the electric motor drives a spindle, which has a thread. The thread of the spindle cooperates with a mating thread of the valve lifter. By rotating the spindle, the valve lifter can be moved perpendicularly to the direction of rotation. The position of the valve lifter and therefore the flow rate can thus be set very accurately by the electric motor. 
     In a further refinement, a control and evaluation unit is provided, which is designed to charge the electrical energy store. 
     The charging of the energy store is in this case controlled by the control and evaluation unit. This contains electronic components, such as ICs, which detect a charged state of the energy store and charge said energy store as required. By setting the required amount of current, the control and evaluation unit prevents the on-board power supply system from being overloaded. The charged state of the energy store is preferably monitored permanently by the control and evaluation unit, and the charging is terminated in accordance with the charged state. The control and evaluation unit thus simultaneously forms an overcharge protection. 
     In a still further refinement, the bypass and/or the actuator is/are also controlled by the control and evaluation unit. On the whole, a particularly more compact and modular design of the valve can thus be achieved. 
     In a further refinement, the valve has a valve housing, wherein the control and evaluation unit is arranged in the valve housing. To this end, the valve housing preferably has a separate installation space, in which the control and evaluation unit is arranged. For example, this may be a side flange with a cover. It is advantageous in this case if the control and evaluation unit is particularly well protected against environmental influences. In addition, the control and evaluation unit in the separate installation space can be reached particularly well for maintenance and repair purposes. 
     In particularly preferred refinements, the installation space is impervious to dirt and is watertight. The control and evaluation unit is thus protected particularly well against environmental influences. This leads to a further improvement of the robustness of the valve. 
     A further advantage is that the control and evaluation unit is located in the vicinity of the actuator. Supply and control lines from the control and evaluation unit to the actuator can thus be very short. An energy loss between the control and evaluation unit and the actuator is thereby minimized, such that power can additionally be saved. Furthermore, a susceptibility to faults, for example as a result of mechanical damage of supply lines or control lines to the actuator, is minimized due to the vicinity. On the whole, a particularly more reliable use of the valve is thus ensured. 
     In a further refinement, the control and evaluation unit comprises the energy store. This provides the advantage that the control and evaluation unit can be produced jointly with the energy store in one production process, such that cost-effective production is achieved. In addition, there is the additional advantage that a modular design of the valve is achieved. For example, all relevant control components can be replaced at the same time and in a simple manner by one module in the event of a repair. 
     In a further refinement, the control and evaluation unit is designed to determine the valve position. The valve position is preferably determined on the basis of an electrical current, which is received by the actuator. The valve is firstly initialized in the event of start-up. The initialization brings the valve lifter into a defined starting position. This can be achieved for example by complete closing or opening of the valve. A relative movement of the valve lifter can be established on the basis of the electrical current. Mechanical constraints, for example a thread pitch of the spindle, are to be taken into account in accordance with the specific embodiment of the valve. The valve position can then be determined on the basis of the starting position and the relative movement. 
     One advantage is that limit switches for the valve lifter can be omitted. Limit switches are typically used to monitor the end positions of the valve lifter. They are then closed by the valve lifter when said valve lifter reaches one of the end positions. Components and additional signal lines can thus be saved as a result of the determination of the valve position by means of the control and evaluation unit, which enables economical production. In addition, possible fault sources are thus overcome, and therefore a valve that is more robust is provided. 
     A further advantage is that, on the basis of the valve position, it is possible to ascertain the flow rate of spray medium through the valve. A flowmeter on the valve can thus be replaced. The information concerning the flow rate can thus be monitored by the control and evaluation unit or by an external operating unit. The determination of the flow rate enables an even more precise delivery of spray medium for each area of ground. In particular, it is made possible in conjunction with a GPS system to store not only the areas of ground that have already been sprayed, but also the amount of spray medium sprayed into the respective areas of ground. A homogenous delivery of spray medium can thus also be set over the boom. In addition, the flow rate can be output to the operating unit for a user of the spraying machine. 
     In a further refinement, the control and evaluation unit comprises a fault detector, which is designed to check the power supply of the valve. The control and evaluation unit thus monitors the power supply of the valve, for example from the on-board power supply system. A fault in the power supply can then be detected in particular when a sharp fall in current is detected within the power supply or a cable break is identified as a result of a resistance measurement. 
     If the fault detector detects a fault, the valve is thus closed, preferably automatically, by the control and evaluation unit. This prevents an uncontrolled leakage of the spray liquid. The closure is then also ensured by the energy store if the power supply fails completely. The valve is thus formed as an opening valve by the control and evaluation unit. In other words, the valve is automatically always closed if no power supply is provided. The valve is advantageously designed without a return spring (that is to say springlessly). Its function is then implemented by the fault detector. Power is thus saved during operation of the valve. 
     In a further refinement, the control and evaluation unit reopens the valve after an automatic closure if the fault detector no longer identifies the fault. A lasting impairment of the operation due to sporadically incorrectly identified faults is thus prevented. 
     In a further refinement, the control and evaluation unit comprises a flicker control. The actuator is then controlled by means of the flicker control if required. The flicker control controls the actuator in such a way that it performs a periodic movement with a defined number of movement strokes and a defined amplitude. Due to the periodic movement, the valve lifter can be shaken free. This preferably occurs automatically as soon as the control and evaluation unit has identified a functional fault, in particular if the valve lifter is stuck or stiff. The control and evaluation unit can identify the sticking or the stiffness of the valve lifter for example on the basis of the current consumption of the actuator. If this is unusually high, a defect of this type is to be assumed and the control and evaluation unit activates the flicker control. 
     With use of an electric motor as the actuator, the electric motor is thus rotated back and forth. This rotates the spindle, whereby the valve lifter is moved up and down. The flicker control thus enables the valve lifter to be shaken free. The control and evaluation unit is preferably designed to perform at least three switching cycles, that is to say six movement strokes, of the valve lifter within the scope of flicker operation. 
     The capacity of the energy store is therefore preferably designed such that at least the three switching cycles, that is to say six switching movements, of the actuator are ensured. It is thus ensured that even a very stiff or heavily stuck valve lifter can be shaken free. In addition, sufficient electrical energy is thus provided for the valve to then be closed again, without the need for an external power supply. 
     In a further refinement , the control and evaluation unit has a BUS interface. The control and evaluation unit may thus have a separate control connection in the form of a BUS interface. The power supply of the valve can therefore be isolated from a control signal guide. This has the advantage that, with use of a multiplicity of valves, supply and control lines can be saved. 
     In a particularly simple and cost-effective embodiment, the valve is supplied with current and also controlled via two electrical lines. For this purpose, voltage pulses can be sent through the electrical lines. The desired direction of rotation and also the duration of rotation can be determined by the control and evaluation unit on the basis of the flank directions and the pulse length of the voltage pulses. In addition, it is conceivable in the control and evaluation unit to use electronic circuits, which can be addressed with an address via the electrical lines in accordance with the principle of a series interface and can then be activated accordingly. 
     In a further refinement, the BUS interface is a CAN BUS interface. The use of a CAN BUS provides the advantage that the amount of electrical lines to the valves can be highly reduced. Specifically, no cable harness has to be laid from the on-board power supply system of the agricultural machine to the individual valves. The valves can be connected in parallel to a common supply line for the supply with current. At the same time, they can be activated via a common control line. 
     A further advantage is that the CAN BUS is capable of being woken up. Here, “capable of being woken up” means that the valve can be operated in a power-saving mode until the valve is actually operated in order to change the valve position. Power can thus be saved very effectively. 
     Furthermore, it is conceivable to use an ISO BUS according to ISO 11783 as a BUS interface. An ISO BUS is widespread in agricultural engineering, and the valves can therefore be integrated easily into existing systems. 
     The design of a system of valves can be highly simplified by the use of the BUS interface. Costs during production can thus be reduced and the reliability can thus be increased. 
     In a further refinement, a diagnosis arrangement is provided, which is designed to check the readiness for operation of the control and evaluation unit. The diagnosis arrangement then monitors the control and evaluation unit. This can occur by means of a permanent monitoring during operation and/or by means of an initial check during start-up of the control and evaluation unit. The readiness for operation of each valve is thus checked during start-up of the spraying machine, and reliable and robust operation is thus ensured. 
     Alternatively or additionally, the diagnosis arrangement checks the position, clearance and readiness for operation of the actuator. In preferred refinements, the diagnosis arrangement also checks the voltage of the power supply and the operability of the energy store. Here, it is advantageous that the readiness for operation of the entire valve is checked regularly and that fault-free operation can thus be ensured. 
     In a further refinement, a display unit is provided. Said display unit may be designed as an LED. The LED is activated by the control and evaluation unit and for example can indicate the readiness for operation of the valve by illumination or non-illumination. Alternatively or additionally, fault codes can also be output by flashing signals. 
     In an alternative or additional refinement, it is conceivable for the control and evaluation unit to output a feedback to an external display unit (such as the operating unit). The output can be made for example via the BUS interface. In particular, the valve that is currently open, closed or defective can thus be indicated to a user. 
     It is advantageous that faulty valves can be identified immediately. Furthermore, with use of the fault code, the user can immediately identify which fault is present. The user can thus take appropriate countermeasures with confidence. 
     In a still further refinement, the control and evaluation unit comprises a data memory, which stores data detected from the valve. For example, these data may be the number of switching cycles made, a current temperature of the actuator, an applied voltage across the valve, an applied current across the valve and/or a number of faults. The data store provides the possibility of a more detailed evaluation in the event of a fault, and therefore maintenance measures can be carried out easily and quickly. In addition, it is conceivable that, in the event of a fault, the content of the data memory is output to the operating unit, and therefore a diagnosis can be made directly by the user. 
     It goes without saying that the features mentioned above and those yet to be explained hereinafter can be used not only in the respective combination specified, but also in other combinations or in isolation, without departing from the scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the invention are illustrated in the drawing and will be explained in greater detail in the following description. In the drawing: 
         FIG. 1  shows a rear view of a schematic illustration of a spraying machine, 
         FIG. 2  shows a perspective illustration of a preferred exemplary embodiment of the new valve, 
         FIG. 3  shows the valve from  FIG. 2  with an opened side flange, 
         FIG. 4  shows a plan view of the valve from  FIG. 2 , 
         FIG. 5  shows a side view of the valve from  FIG. 2 , 
         FIG. 6  shows a sectional view of the valve from  FIG. 2 , 
         FIG. 7  shows an enlarged illustration of a detail of the sectional view from  FIG. 6 , 
         FIG. 8  shows a replacement circuit diagram of a preferred exemplary embodiment of a control and evaluation unit, 
         FIG. 9  shows a first flow diagram of a first part of a presented method, 
         FIG. 10  shows a second flow diagram of a second part of the presented method, 
         FIG. 11  shows a third flow diagram of a third part of the presented method, and 
         FIG. 12  shows a fourth flow diagram of a fourth part of the presented method. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  shows an agricultural spraying machine, which is denoted in its entirety by the reference numeral  10 . It consists of an agricultural machine  12  in the form of a tractor, to which a boom  14  is fastened. The boom  14  has five sections  16 . These can be pivoted relative to one another in order to fold in the boom  14  for transport. A tank  18  is arranged on the boom and contains a spray liquid  20 . Spray nozzles  22  are distributed along the entire boom  14 . The spray nozzles  22  are connected to the tank  18  via tube lines so that the spray liquid  20  can be conveyed to the spray nozzles  22 . The tube lines are not illustrated. The spray nozzles  22  are used to dispense the spray liquid  20  as spray jets  24  onto the ground  26 . The spray nozzles  22  can be activated individually by a multiplicity of the valves according to the invention. 
     As is shown by way of example in  FIG. 1 , only the outer six spray nozzles  22  are in operation in each case. Merely areas of ground  28  and  28 ′ are therefore sprayed with the spray liquid  20 . Due to the possibility of being able to activate each spray nozzle  22  individually, the ground  26  can be sprayed particularly exactly with the necessary amount of spray liquid  20 . In particularly preferred exemplary embodiments, the agricultural machine  12  is equipped with a GPS receiver and an on-board computer. The GPS receiver and the on-board computer track the movements of the spraying machine  10  and store the areas of ground already sprayed. If the boom  14  pivots over an area of ground  28 ,  28 ′ that has already been sprayed, the on-board computer then automatically switches off the corresponding spray nozzles  22 . Multiple spraying of the areas of ground  28 ,  28 ′ is thus prevented. 
     An exemplary embodiment of a valve  30  is illustrated in various views in  FIGS. 1 to 7 . During operation, the valve  30  is part of a nozzle module (not illustrated). The nozzle module comprises a spray nozzle holder. The spray nozzle holder has connections for a spray medium line, the spray nozzle  22  and the valve  30 . The spray medium  20  is guided from the spray medium line, through the spray nozzle holder, to the valve  30 . The valve  30  then controls the flow rate to the spray nozzle  22 . The spray medium  20  is dispensed at the spray nozzle  22 . 
     To connect the valve  30  to the spray nozzle holder, a coupling  32  is provided. The coupling  32  is connected to a valve housing  34 , which has a cover  36 . The cover  36  is fastened by four screws  38 . The valve housing  34  encapsulates a motor arranged therein and protects said motor against environmental influences. In addition, the valve housing  34  has a side flange  40 , which can be opened via a cover  42 . The cover  42  is fastened by six screws  44 . The side flange  40  is shown in an exploded illustration in  FIG. 3 . A control and evaluation unit  46  is arranged inside the side flange  40 . The control and evaluation unit  46  is designed as a printed circuit board, on which a multiplicity of electronic components is arranged. In preferred exemplary embodiments, seals are assigned to the cover  36  and the cover  42  and seal the valve housing  34  so as to be largely watertight and impervious to dirt. 
       FIG. 7  shows an enlargement of the sectional illustration A-A from  FIG. 6 . The coupling  32  comprises an opening  48 , which is connected during use of the valve  30  to the spray nozzle holder. In order to produce a liquid-tight connection, two O-rings  50  and  52  are provided, which are arranged concentrically to one another. The O-ring  52  is held by an intermediate bushing  54 , which separates an inlet region  56  from an outlet region  58 . The outlet region  58  is cylindrical in this case. It is surrounded radially by the inlet region  56 . The O-ring  50  seals the valve  30  to the exterior. A spacer sleeve  60  is arranged in the intermediate bushing  54 . The spacer sleeve  60  is recessed laterally in part so that, within the valve  30 , spray liquid  20  can reach into the outlet region  58  from the inlet region  56 . 
     The coupling  32  is connected in a liquid-tight manner via an O-ring  62  to a guide part  64 . The guide part  64  guides a valve lifter  66 . The valve lifter  66  is arranged concentrically in its longitudinal extent with the inlet region  56  and the outlet region  58 . A further O-ring  68  is arranged around the valve lifter  66  and prevents the spray liquid  20  from crossing into the guide part  64  along the valve lifter  66 . This O-ring  68  is supported between the guide part  64  and a supporting ring  70 . A guide block  72  is arranged on the valve lifter  66  and is interlockingly connected to the valve lifter  66 . The guide block  72  is guided in a guide groove  74  of the guide part  64 . The guide block  72  and the guide groove  74  thus define a direction of movement  76  of the valve lifter  66  along its longitudinal extent. At the same time, they prevent a rotation of the valve lifter  66  within the valve  30 . 
     Retaining recesses  80  are provided in the guide part  64  and are designed to receive a retaining clip  81 . Said clip is plugged through openings in the valve housing  34  and then engages in the retaining recesses  80 . The guide part  64  is thus interlockingly connected to the valve housing  34 . Secure retention is achieved by this type of connection, although the valve can nevertheless be disassembled very quickly. 
     The guide part  64  is connected in a liquid-tight manner via a further O-ring  78  to the valve housing  34 . A motor  82  is arranged inside the valve housing  34 . A spindle  84  is located between the motor  82  and the valve lifter  66 . The spindle  84  has a thread on the side of the valve lifter  66 . The thread of the spindle  84  meshes in a region  86  with a corresponding mating thread of the valve lifter  66 . By rotating the spindle  84 , the valve lifter  66  can be moved along the directions of movement  76 , that is to say in the direction of its longitudinal extent. For this purpose, the spindle  84  is arranged in a stationary manner in the direction of movement  76  and is mounted rotatably by a ball bearing  88 . For rotation of the spindle  84 , it has a groove  90  on the side of the motor  82 . A drive shaft  92  of the motor  82  engages in this groove  90 . The drive shaft  92  is flattened laterally for this purpose, so that the spindle  84  can rotate by means of an interlocking connection. 
     The motor  82  can be operated very accurately in two directions of rotation. If the motor  82  is operated, it then rotates the spindle  84  with the drive shaft  92 . Due to the thread of the spindle  84  and of the valve lifter  66 , the valve lifter  66  is displaced along the direction of movement  76 . The valve lifter  66  is illustrated here in a valve position that fully closes the valve  30 . By actuation of the motor  82 , the valve lifter  66  can be moved from the illustrated valve position only in the direction of the motor  82 . The valve  30  is thus opened and the spray liquid  20  flows from the inlet region  56  into the outlet region  58 . Due to the geometric embodiment of the tip of the valve lifter  66  in the outlet region  58 , the valve is not limited to discrete opening or closing. The desired flow rate of spray liquid  20  is defined in accordance with the valve position of the valve lifter. 
     A replacement circuit diagram of the preferred exemplary embodiment of the control and evaluation unit  46  is illustrated in  FIG. 8 . Reference numeral  94  denotes a constant power source, which is fed from the on-board power supply system of the spraying machine. It constitutes a power supply for the valve  30 . In addition, it limits a supply current for the control and evaluation unit  46  to a fixed maximum value. In particularly preferred exemplary embodiments, this maximum value is 100 mA. The positive pole of the constant power source  94  is connected to the control and evaluation unit  46  in order to supply said unit and the motor  82  with electrical current. 
     The control and evaluation unit  46  comprises a DC/DC converter  98 , which converts the variable input voltage from the on-board power supply system to a defined constant direct voltage, which is suitable for the operation of the components of the control and evaluation unit  46 . The on-board power supply system preferably supplies an electrical voltage in the range of 12 or 24 volts, which is converted in the DC/DC converter  98  to 5 volts. The DC/DC converter  98  enables the adaptation of the valve  30  to a wide operating voltage range so that the valve  30  can be operated with different electrical voltages. It also ensures an optimal adaptation of the voltage to the motor characteristics. This leads to high efficiency and therefore to an energy saving. 
     A capacitor  100  and a voltmeter  102  are connected parallel to the DC/DC converter  98 . The capacitor  100  is used to balance voltage fluctuations of the constant power source  94 . The voltmeter  102  measures a voltage U 1 , which is applied to the constant power source  94 . Furthermore, an output voltage U 2  of the DC/DC converter  98  is measured by a further voltmeter  104 . 
     An energy controller  106  is operated by the output power of the DC/DC converter  98 . The energy controller  106  controls the charging of the energy stores  108 . It is connected to ground  96  for a required operating voltage. The energy stores  108  are designed in the illustrated exemplary embodiment as capacitors  108 , in particular as electrochemical double-layer capacitors (“supercapacitors”). For the charging of the capacitors  108 , the energy controller  106  first determines the charged state of said capacitors. It then charges the capacitors  108  when their charged state falls below a predefined minimum level. If the capacitors  108  are fully charged, the charging process is stopped, and an overcharging is thus prevented. 
     The stored electrical energy is conveyed as required from the capacitors  108 , via a coil  110  and an ammeter  112 , to the motor  82 . A quenching circuit is provided parallel to the motor  82  and ammeter  112 . Said circuit consists of a capacitor  114  and a diode  116 . 
     A further DC/DC converter  118  is additionally operated by means of the electrical energy from the capacitors  108 . The DC/DC converter  118  controls the applied voltage to a value with which a microcontroller  120  can be operated. The voltage may be, for example, converted to 3 V. The microcontroller  120  is connected to ground  96  for a required operating voltage. 
     The microcontroller  120  is used as an input and output device of the control and evaluation unit  46 . It is also used as a control and regulation device for the motor  82 . In order to monitor the motor  82 , an interface  122  is provided. A motor current I determined by the ammeter  112  is detected via the interface  122 . The control and evaluation unit  46  determines the valve position on the basis of the electrical motor current I, which is received by the motor  82 . An angle of rotation of the motor  82  is established in accordance with the motor current I and known motor characteristics. The angle of rotation is then converted together with the pitch of the thread for the movement of the valve lifter  66  into a relative axial displacement of the valve lifter  66 . This axial displacement then describes the change from the original position of the valve lifter  66  into the new position of the valve lifter  66 . The absolute valve position can then be determined on the basis of the relative axial displacement in conjunction with the starting position. 
     Furthermore, it is monitored on the basis of the motor current I whether the motor  82  is loaded beyond the magnitude to be expected. In this case, the control and evaluation unit  46  draws conclusions as to whether an end position of the valve lifter  66  is reached or whether the valve lifter  66  is stuck or stiff. 
     Furthermore, a temperature of the motor  82  is measured via an interface  124 . The control and evaluation unit  46  monitors the state of the motor  82  on the basis of the temperature in order to additionally prevent the overload of the motor  82 . 
     Control signals are sent from the control and evaluation unit  46  to the motor  82  via an interface  126 . The control signals are provided in the form of a voltage, of which the polarity defines the direction of rotation. Alternatively, the control signals may also be produced in the form of a pulse-width modulation. 
     Furthermore, the microcontroller  120  detects the voltage U 1  of the ammeter  112  via an interface  128 . In addition, the voltage U 2  detected by the voltmeter  104  is forwarded via an interface  130  to the microcontroller  120 . The microcontroller  120  can determine fluctuations in the voltage supply and can identify faults in the power supply of the constant power source  94  on the basis of the voltages U 1  and U 2 . 
     The microcontroller  120  controls the energy controller  106  at a signal input  134  via a further interface  132 . In addition, the energy reserves present in the energy stores  108  may also detected by the microcontroller  120 , and therefore a readiness for operation of the valve  30  is detected and ensured by the microcontroller  120 . 
     The microcontroller  120  also provides a flicker control  136 . The flicker control  136  generates periodic alternating movements of the motor  82  so that it shakes free the valve lifter  66 . Specifically, a quick succession of movements back and forth is generated so that locks or frictional resistances can be overcome. The flicker control  136  is then used by the microcontroller  120  if it is identified on the basis of the detected motor current I that the valve is heavily soiled or gridlocked. 
     In addition, the microcontroller  120  comprises a diagnosis arrangement  138 . When the operation of the valve  30  is started, the diagnosis arrangement  138  checks whether the electrical components of the valve  30  are ready for operation. Preferably, the readiness for operation in particular of the motor  82 , the constant power source  94 , the energy controller  106  and the microcontroller  120  is checked. 
     Furthermore, the microcontroller  120  comprises a data store  140 , in which data concerning the operation of the valve  46  are stored. These data are stored for diagnosis and maintenance purposes. They contain information regarding the performed switching cycles of the valve  30 , the temperature of the motor  82 , the applied voltage and the applied voltage across the valve  30  and also a number of faults present. 
     In addition, the microcontroller  120  has a fault detector  142 . The fault detector  142  monitors the power supply of the valve  30 . In the event of a fault, for example with a sharp fall in current as a result of a cable break, the fault detector  142  activates the motor  82  via the interface  126 . The motor  82  is activated here in such a way that it brings the valve lifter  66  into a closed position. The valve  30  is thus designed in terms of control as an opening valve. In other words, the valve  30  is designed such that, in the event of a fault or in the case of faulty actuation, it is automatically closed. Due to the fault detector  142 , a closing spring is replaced compared to conventional valves. The omission of the closing spring means that much less electrical energy is required to open the valve  30  compared to conventional valves. 
     The energy stores  108  are designed in terms of their capacity such that the flicker control  136  and the fault detector  142  can be used at any time. Said energy stores provide enough electrical energy such that at least three switching cycles can be carried out. With a sudden drop in current, it is thus ensured that the valve lifter  66  can be shaken free and that the valve  30  can be reliably closed. Operation that is more reliable and more robust is thus ensured. 
     Furthermore, the microcontroller  120  comprises a BUS interface  144 , which serves as an input and output unit for the control and evaluation unit  46 . In preferred exemplary embodiments, an external operating unit communicates bidirectionally via the BUS interface  144  with the valve  30 . Different operating modes in the microcontroller  120  can be set very easily from the operating unit via the BUS interface  144 . For example, a user is able to choose manually between a normal operating mode or the flicker operating mode. In addition, a feedback is implemented from the control and evaluation unit  46  to the operating unit for an output to the user. The feedback contains information regarding the readiness for operation, the operating state and faults of the valve. For example, it may also contain the data from the data memory. Furthermore, the transmission of information concerning the valve position or the flow rate of spray medium  20  in the valve  30  is conceivable. 
     The BUS interface  144  is designed as a CAN BUS interface. It has the advantage that only a few control lines have to be used for all valves  30  of the spraying machine  10 . In addition, the CAN BUS is capable of being woken up. Here, “capable of being woken up” means that the valve  30  can be operated in a power-saving mode until the valve  30  is actually operated in order to change the valve position. In alternative exemplary embodiments, an ISO BUS or a series interface can also be used as a BUS interface  144 . 
     By means of the BUS interface  144 , the use of the microcontroller  120  enables a reliable and robust control of the valve  30  with simultaneous saving of electrical lines. 
     In addition, the control and evaluation unit  46  comprises a display unit in the form of an LED  146 . The LED  146  is attached to the valve  30  so as to be visible from the outside. It is used to indicate the readiness for operation of the valve  30 . In addition, a flashing code is emitted when a fault is identified by the fault detector  136  or the diagnosis arrangement  138 . A user can thus identify immediately which valve  30  is defective at the boom  14 . At the same time, he can immediately identify which defect is present specifically. 
     Furthermore, a bypass  148  is provided within the control and evaluation unit  46  in this preferred exemplary embodiment. The bypass  148  bypasses the energy store  108 . It can supply both the microcontroller  120  and the motor  82  directly with electrical energy from the DC/DC converter  98 . The bypass  148  comprises a capacitor  150 , which forms a DC decoupling from the on-board power supply system. Within the bypass  148 , two switchable diodes  152  and  152 ′ are provided, which can be controlled by the microcontroller  120 . As soon as the microcontroller  120  identifies a fault of the energy stores  108 , the diodes  152  and  152 ′ are switched accordingly. The diode  152  then releases the bypass line around the energy store  108  in order to supply current to the motor  82  and the microcontroller. By contrast, the diode  152 ′ blocks the energy feed from the bypass line to the capacitors  108  so that the total electrical energy is available for the motor  82 . In addition, the diode  152 ′ protects the energy controller  106  against the energy feed from the bypass line. In preferred embodiments, the energy controller  106  is designed as a charging IC. This is protected by the diode  152 ′, since a voltage with incorrect polarization would otherwise be applied when the bypass  148  is open. This could lead to a defect within the charging IC. The diode  152 ′ can also be designed as a “normal” diode, which allows the current flow in one direction and blocks it in the other direction. 
     Alternatively, it is conceivable for the diode  152  to be a pin diode. The pin diode can be connected by means of a relatively strong energy pulse, and therefore no additional control line is required. 
     In a further alternative, it is conceivable for the energy controller  106  to switch the switchable diodes  150  and/or  152 ′. This has the advantage that the energy controller  106  is not fed by the energy supply from the bypass  148 . A particularly reliable connection of the bypass  148  is thus ensured when there is a defect of the energy store  108 . 
     The bypass  148  is then also used when it is identified that the energy stores  108  are insufficiently charged for a requested operation. Then, the microcontroller  120  switches the switchable diodes  152  and  152 ′, likewise in the above-described manner. 
     The bypass  148  thus ensures a direct access to the valve  30 , even when there is a fault at the energy stores  108 . A defective valve  30  can thus initially continue to be used, and the operation of the spraying machine  10  does not have to be interrupted due to a defective valve  30 . 
     Furthermore, the switchable diodes  152  and  152 ′ are then switched back when the energy supply is stored again by the energy stores  108 . This means that the bypass  148  is then closed again when the energy stores  108  are charged again and are ready for operation. 
     A number of flow diagrams are illustrated in  FIGS. 9 to 12  and, on the whole, describe a first exemplary embodiment of the presented method. 
       FIG. 9  describes a starting procedure in the event of start-up of the valve  30 . In a step  154 , the operating voltage is applied to the valve  30 . A step  156  follows, in which the energy stores  108  are precharged in order to ensure stable operation of the control and evaluation unit  46 . The stores are precharged until it is identified in a step  158  that the input voltage at the control and evaluation unit  46  is greater than a minimum operating voltage. In a particularly preferred exemplary embodiment, the control and evaluation unit  46  is operated with an on-board power supply voltage of 12 volts. In this case, the stores are precharged in step  156  until a voltage that is greater than  5  volts is detected in step  158 . 
     Once this has taken place, an initialization is carried out in step  160 . The initialization is described in detail on the basis of  FIG. 10 . After successful initialization, an output of the initialization is checked for a fault signal in a step  162 . If there is no fault signal, the energy stores  108  are then fully charged in a step  164 . 
     The charged state of the energy stores  108  is then checked in a further step  166 . If complete charging has not yet been achieved, step  164  is then repeated until complete charging is achieved. The valve  30  then passes into an operating mode in step  168 . The operating mode will be described in detail on the basis of  FIG. 12 . 
     If, in step  162 , a fault signal is identified, a fault treatment is thus performed in step  170 . The fault treatment is described in detail on the basis of  FIG. 11 . Once the fault treatment has been performed, there is a return to step  158  so that complete charging is checked once again and the system is initialized again. 
       FIG. 10  shows the initialization in step  160  in detail. The initialization starts in step  172 , which is followed by a check of the CAN BUS in step  174 . In a step  176 , an output of the step  174  is evaluated. If a CAN BUS is present, it is initialized as an input and output unit in a step  178 . It is then checked in step  180  whether the CAN BUS functions without fault. 
     If the output of step  180  is positive, there is then an end position check of the valve lifter  66  in step  182 . It is thus ensured that the valve lifter  66  is moved out of a defined starting position during operation. An absolute position of the valve lifter  66  and therefore the valve position can thus be determined at any moment on the basis of the movement changes, which are detected via the current consumption of the motor  82 . Furthermore, it is thus ensured that all valves  30  of the boom  14  are closed during the switch-on procedure. If, in a step  184 , it is identified that the valve  30  is closed, the initialization is then terminated in a step  186  and the method from  FIG. 9  is carried out. 
     If, in step  176 , no CAN BUS is identified, a check is then carried out in a step  188  for alternative BUS systems, such as an ISO BUS or 3Wire. Step  190  evaluates an output of the check from step  188 . If an alternative BUS system was identified, this is thus initialized in step  178  and is subsequently treated correspondingly to the CAN BUS. If, in step  190 , no further BUS system is identified, a fault signal is thus output in a step  192  and the initialization is terminated in step  194 . The method is then continued in  FIG. 9 , wherein the fault treatment in step  170  is performed due to the fault signal. 
     If, in step  180  of  FIG. 10 , a fault is identified during initialization from step  178 , a fault signal is also output here in a step  196  and the initialization is terminated in step  198 . The method is also then continued here in  FIG. 9 , wherein the fault treatment due to the fault signal is performed in step  170 . 
     If it has been identified on the basis of the end position check in step  182  that the valve  30  is not closed, step  184  thus triggers a fault protocol. The fault protocol is carried out in step  200  and stores all data from the microcontroller  120 . In addition, the fault is output as a flashing code via the display unit  146 . 
       FIG. 11  shows the fault treatment from step  170  of  FIG. 9  in detail. The fault treatment is started in a block  202 . Faults are first read out from the data memory  140  in a step  204 . The read-out data are checked in a step  206 . If no data are present, the fault treatment is thus terminated in a step  208 . The method is then continued in  FIG. 9 , wherein it is then continued in step  164  for lack of a fault notification. 
     If, in step  206 , fault data are identified, the flicker control  136  is thus actuated in a step  210  and the valve lifter  66  is shaken free. In a step  212 , it is then checked whether the process of shaking free the valve lifter was successful. If so, the fault treatment is terminated in step  208  and the method is continued in  FIG. 9  in step  158 . 
     If the process of shaking free the valve lifter was not successful, the end positions of the valve lifter  66  are adopted in a step  214 . In step  216 , it is then checked whether the end positions were successfully adopted. If so, the fault treatment is terminated in step  208  and the method is continued in  FIG. 9  in step  158 . 
     If the end positions were not successfully adopted, a fault signal is thus output in step  218  and the fault treatment is terminated in step  220 . 
       FIG. 12  shows the step  168  from  FIG. 9  in detail. Step  168  includes the operating mode of the valve  30 . The operating mode is started in a step  222 . In a step  224 , the voltage of the constant power source  94  is then detected. In step  226 , the value of the detected voltage is then checked. If the voltage is equal to the desired supply voltage, a transition is then made to the next step  228 . Preferably, the desired voltage is the voltage of the on-board power supply system with 12 V. 
     In step  228 , the temperature of the motor  82  is detected via the interface  124 . The temperature is then evaluated in step  230 . If the temperature corresponds to the desired default settings, the valve  30  can thus be opened in accordance with a control request. This occurs in a step  232 . If, in step  230 , it is identified that the temperature does not correspond to the requested specifications, the operating mode is restarted and continued in step  224 . 
     A further check of the voltage of the constant power source  94  is made in step  234 , when the valve  30  is to be closed. If the desired voltage is applied, the valve is thus closed in step  236 . 
     The entire method can then be terminated in step  238 . 
     If the check of the voltage of the constant power source  94  in step  226  indicates that the voltage is not equal to the desired voltage, an emergency shutdown is triggered in step  240 . A fault signal is then output in step  242  and the operation of the valve  30  is then terminated in step  244 . 
     The procedure is similar with an incorrect voltage in step  234 . Here, an emergency shutdown is likewise triggered in the step  240 ′. This is followed by the output of a fault signal  242 ′. The operation of the valve  30  is then terminated in the step  244 ′. 
     On the whole, the operating mode is performed as a cycle, provided there is no emergency shutdown. The cycle begins after step  236  and returns the method back to step  224 .