DE102019203102A1 - Spray equipment and process - Google Patents

Abstract

The invention relates to a spray device (1) for dispensing liquids, in particular for agricultural purposes, with at least one spray nozzle (4) for spraying out the liquid and with at least one mixing device (15) which has at least one mixing chamber (16) Mixing chamber (16) at least one first inlet (20, 21) for a carrier liquid (TF), at least two second inlets (17-19) for different active substances (A, B, C) and at least one outlet connected to the spray nozzle (4) (22) open, each of the inlets (17-21) being assigned an actuatable valve (23-27). A device (28) is provided which, when used as intended, switches the valves (23-27) in a pulse-width-modulated manner in such a way that a constant volume flow results regardless of the actuation of the valves (23-27).

Description

The invention relates to a spray device for dispensing liquids, in particular for agricultural purposes, with at least one spray nozzle for spraying out the liquid and with at least one mixing device which has at least one mixing chamber, the mixing chamber at least one first inlet for a carrier liquid and at least two second inlets for an active substance agent and at least one outlet connected to the at least one spray nozzle, and wherein each of the inlets is assigned an actuatable valve.

The invention also relates to a method for operating such a spray device.

State of the art

In today's agricultural plant protection measures, the spray mixture consisting of at least one active substance, in particular an active substance liquid, such as, for example, pesticides, and a carrier liquid, in particular water, must be premixed before the actual application on a field. At the end of the application, the tank providing the respective agent must generally be completely emptied and cleaned in the field. It is therefore hardly possible to react to the nature of the field and to the actual local need for pesticides. The complete mixed spray liquid is therefore fully applied to the field.

Systems are also known in which active substance liquids are carried undiluted in their own tank and are only mixed with the carrier liquid when required when they are applied to the field. For this mixing process, it is necessary to be able to dose the active substance liquid with the carrier liquid as required. This metering process is also referred to as direct feed and requires a complex construction of a spray device, which must provide the necessary valves and the like for this.

Spray devices of the type mentioned are, for example, from the laid-open specification WO 00/59321 known. This discloses a spray device with a mixing device which has an actuatable valve for each inlet.

Disclosure of the invention

The spray device according to the invention with the features of claim 1 has the advantage that a rapid and situation-appropriate plant protection measure can be carried out, whereby it is ensured that the total application rate or the volume flow supplied to the at least one spray nozzle remains constant regardless of the number of active substances, in particular active substance liquids, added . This ensures optimal application of the pesticides in a field. According to the invention, it is provided for this purpose that the spray device has a device which, when used as intended, switches the valves in a pulse-width-modulated manner in such a way that a constant volume flow results in the process regardless of the actuation of the valves. The invention therefore provides that the valves are switched in a pulse-width-modulated manner. This means that the valves for setting a volume flow are not controlled in such a way that they set a flow cross-section between a maximum possible flow cross-section and a closed position to set the volume flow, but in such a way that they provide a desired volume flow by means of pulsed opening and closing over time. For this purpose, the respective valve is switched on, i.e. opened, at least once within a switching cycle. The duty cycle within the switching cycle determines the average volume flow set. If the valve is switched on for the entire duration (100%) of the switching cycle, the result is a maximum volume flow. For example, if the valve is switched on for only 50% of the duration of the switching cycle, the volume flow is halved. This pulse-width-modulated circuit, which is not to be confused with a pulse-width-modulated control of an actuator of the respective valve, in which the flow cross-section of the respective valve is influenced by a pulse-width-modulated current, results in a desired volume flow through the respective valve on average over time, with a pulse-width-modulated Switching of all valves of the spray device or the mixing device ensures that an overall constant volume flow results, which is fed through the outlet of the spray nozzle. The pulse-width-modulated operation makes it possible to adjust the concentration of each individual active substance liquid and also of the carrier liquid at the outlet, even if the ratio of carrier liquid to active substance liquid is constant in the fluid-carrying supply lines. In this way, the composition can be used with a constant volume flow and thus also a constant spray pattern the applied liquid or spray liquid can be continuously controlled. In the event that only one active ingredient has to be applied, for example a fungicide, it is possible to load the active ingredient-carrying lines with the individual active ingredient and thus achieve an adjustment of the concentration without pulse-width-modulated operation of the individual valves.

In particular, the device is designed to vary a switching frequency, a switch-on duration and / or switch-on time of the valves within a switching cycle when used as intended. This makes it possible to switch the valves in synchronism or at different times, and / or to operate them with the same or different switching frequencies. As a result, different switch-on times are possible, by means of which the volume flow through the respective valve can be adjusted over time. The volume flow is increased in particular by increasing the duty cycle. In order to maintain the total volume flow at the outlet, the volume flow of at least one other valve of the mixing device is reduced when the volume flow of one valve is increased.

According to a preferred development of the invention it is provided that the valves assigned to the inlets are each designed in the same way. This results in a large number of identical parts, which ensures simple assembly and inexpensive provision of the spray device. In addition, this ensures that, due to the same design of the valves, the valves each have the same flow resistance and also provide the same flow cross-sections.

Each of the valves is preferably assigned an electrically adjustable and electrically operating actuator, in particular an electromagnetic or electromotive actuator, which is designed to operate or switch the respective valve. This ensures simple activation and implementation of the control device. The device has in particular a control unit, preferably a microprocessor, which takes over the control of the actuators, depending on a requested plant protection measure or a requested mixing ratio.

Furthermore, it is preferably provided that a pump device for conveying the respective liquid is connected upstream of each valve, the pump devices being designed to provide the same conveying pressure in each case. This is not intended to mean that a separate pump device must be connected upstream of each valve. Rather, this is intended to mean that a common pump device can also be connected upstream of several valves. However, it is important that a pump device is connected upstream of each valve, whether jointly or alone, in order to provide the desired delivery pressure to the respective valve. In particular, a pump device is thus connected upstream of the valves with a common supply line. In particular, it is provided that the pump devices are designed in the same way. Ensuring the same delivery pressure ensures that the valves each provide the same flow volume. This applies both to the inlets of the active substance liquid and to the at least one inlet for the carrier liquid. As a result, the total volume flow is retained if, for example, one valve is closed and another valve is opened.

Furthermore, it is preferably provided that the mixing device has three second inlets for three different active substance liquids. The mixing device thus has a total of at least four inlets. This allows different switching combinations to be achieved, in which one or more active substance liquids are mixed with the carrier liquid and a switchover between active substance liquids can take place without the total volume flow that flows through the drain being changed.

According to a particularly preferred development of the invention it is provided that the mixing device has two first inlets for the carrier liquid. Because there are also two first inlets for the carrier liquid, it is also possible to dose the carrier liquid by switching the two valves assigned to the first inlets on and off. This increases the number of variants of the mixing device, with the output volume flow remaining the same.

The method according to the invention with the features of claim 7 provides that the valves of the mixing device are switched pulse-width-modulated in such a way that a constant volume flow is supplied to one or more spray nozzles through the process regardless of the actuation of the valves. This results in the advantages already mentioned.

According to a preferred further invention, at least two valves are switched in synchronism with one another or offset in time. In particular, a time-shifted switching ensures that Pressure peaks in the total volume flow are minimized. By switching the valves at the same time or in unison, an advantageous mixing, for example of different carrier liquids, is achieved.

Furthermore, it is advantageously provided that at least two of the valves are switched with the same or different frequencies. By selecting the switching frequency, the volume flow through the respective valve, that is to say the respective individual volume flow, can advantageously be set in such a way that a constant total volume flow results at the outlet.

It is also advantageously provided that at least two of the valves are switched with the same or different switch-on times within a switching cycle. This relates to the so-called duty cycle by which the volume of liquid flowing through the valve within the switching cycle is specified, as already mentioned above.

Furthermore, it is provided according to a preferred embodiment that in each switching cycle, in particular with at least five valves present, three valves are opened or switched on at the same time. This ensures that a total volume flow that is as constant as possible is achieved during the application phase or a spraying process.

Furthermore, it is preferably provided that at least one of the valves is or remains switched on beyond a switching cycle. In particular, for this purpose, the switching sequence of the valves is changed from one switching cycle to the next switching cycle in such a way that one of the valves can remain switched on beyond the switch-on cycle, ie from one switching cycle into the following switching cycle. This reduces the number of switching operations for the valve concerned and increases its service life. This is preferably carried out alternately for all valves of the mixing device in order to optimize the service life of the spray device as a whole.

Furthermore, it is preferably provided that the valves are switched in such a way that when the difference in the switch-on duration of the two valves for active substances that have the longest switch-on duration, scaled to the switching cycle duration, is shorter than the switch-on time of a valve for carrier liquid switched within the same switching cycle , this valve for carrier liquid is not switched in this switching cycle. The idea behind this is to reduce switching cycles that are of no consequence for the total volume flow. In the above-mentioned case, it is assumed that the valve for the carrier liquid would have to be closed again due to the short switch-on period before it was fully opened in order to ensure the short switch-on period. As a result, the actually released flow volume through the valve for carrier liquid would be very small. Failure to switch this valve then leads in this case to only a slight impairment of the total volume, which is negligible because the flow volume remains almost constant.

Furthermore, it is preferably provided that the switch-on time of the valve with the longest switch-on duration within a switching cycle is selected such that the valve is centered in time or is set for volume flow averaging.

Furthermore, it is preferably provided that, particularly at high driving speeds, the valves are switched as evenly as possible, so that the same time interval exists between the switching duration of the current switching cycle and the switching duration of the previous cycle and the following cycle.

Furthermore, it is preferred to count how often which valve is switched in order to preferably control the valves as a function of the detected switching numbers in such a way that they have at least approximately the same switching number within a predeterminable time span. In particular, the counting of the switching cycles or the number of switching operations can take place before the actual method is carried out if the circuit diagram for the valves is calculated as a function of the desired plant protection measure. In particular, the switch-on durations, switch-on times and frequencies are then adapted or corrected in such a way that all valves are switched as often as possible.

• 1 eine vorteilhafte Spritzeinrichtung in einer vereinfachten Darstellung,
• 2 eine schematische Detailansicht der Spritzeinrichtung,
• 3 eine schematische Darstellung einer vorteilhaften Mischeinrichtung der Spritzeinrichtung,
• 4 ein Diagramm zur Erläuterung eines vorteilhaften Verfahrens zum Betreiben der Spritzeinrichtung.

Further advantages and preferred features and combinations of features emerge in particular from what has been described above and from the claims. The invention will be explained in more detail below with reference to the drawing. To show

• 1 an advantageous spray device in a simplified representation,
• 2 a schematic detailed view of the spray device,
• 3 a schematic representation of an advantageous mixing device of the spray device,
• 4th a diagram to explain an advantageous method for operating the spray device.

1 shows a simplified representation of a spray device 1 who have a vehicle trained as a tractor 2 has, which has a spray system 3 , having a variety of spray nozzles 4th carries, the spray nozzles 4th via a cross member 5 are arranged distributed next to each other. The vehicle 2 pulls the cross member 5 and the spray nozzles 4th behind you so that the spray nozzles are above a floor 6th to apply pesticides to the soil and any plants on it. The vehicle 2 also contributes several tanks 7th , 8th , 9 and 10 , being in the tanks 7th 8th and 9 a liquid active ingredient A, B or C is kept in stock, and in the tank C a carrier liquid TF, in particular in the form of water. The tanks 7th to 10 are with the spray nozzles 4th connected by one or more mixing devices, which will be discussed in more detail below. Each tank has a pumping device to convey the respective liquid 11 , 12 , 13 and 14th assigned, by means of which the respective liquid can be removed and fed to the mixing device described below. While in the following embodiment three different agent tanks 7th , 8th and 9 shown and described, it is understood, however, that the spray device 1 can also have more or fewer drug agent tanks.

2 shows a simplified detailed view of the spray device 1 in which the four tanks 7th , 8th , 9 and 10 , the associated pump devices 11 to 14th as well as two of the spray nozzles 4th are shown. The spray nozzles 4th is a mixing device 15th upstream, each with the pump devices 11 , 12 , 13 and 14th are connected by appropriate fluid lines. So that each is the mixing device 15th can be acted upon by the respective liquid, the mixing device 15th is designed to set a desired mixing ratio of the individual liquids with one another and the respective spray nozzle 4th feed.

The through the mixing device 15th The spray liquor to be made available consists of the carrier liquid and a plant protection agent, for example A, B or C, or a combination of these. The composition of the spray liquor is typically in the range from 25 to 200 parts by volume of carrier liquid to a proportion of the plant protection agent by volume for liquid and solid plant protection agents in the range of 50 to 20,000 parts by mass of carrier liquid to a proportion by mass of plant protection agents. Of course, other values are also possible. In that the mixing device 15th the respective spray nozzle 4th is connected upstream, there is the advantage that the individual liquids are only mixed shortly before the spray nozzle, so that on the one hand each spray nozzle can deliver an individual composition of the spray liquid, and on the other hand the volume that is obtained from the spray after application of a pesticide Lines of the spray device 1 would have to be removed, in order to keep their components clean, is kept particularly low.

While in the present case the mixing devices 15th directly from a spray nozzle 4th are connected upstream, it is provided according to a further exemplary embodiment that in each case a partial width, that is to say a predetermined number of spray nozzles arranged next to one another 4th , just a mixer 15th is upstream, so that the section of spray nozzles 4th the same spray mixture is applied to the field. It can also be provided that the mixing device 15th the tanks 7th , 8th , 9 , 10 or their pump device 11 to 14th is immediately downstream in order to produce the desired spray liquid at an early stage and all spray nozzles 4th the spray device 1 feed. Each spray nozzle is also used for individual nozzle switching 4th optionally equipped with a simple switching valve, which enables activation and deactivation of the respective spray nozzle.

In the case of a typical application of pesticides with a carrier liquid, it is necessary to keep the total amount used, in particular the amount of carrier liquid, constant. For example, when switching from one plant protection product to a combination of several plant protection products, the total amount applied per spray nozzle should be 4th or remain constant per area to be sprayed. Due to the advantageous design of the spray device 1 It is now possible to supply a constant volume flow to the respective spray nozzle, regardless of which combination of pesticides and carrier liquid is selected and whether this combination is changed during operation.

For this purpose it is provided that the pump devices 11 to 14th are designed to provide the same volume flow and / or the same fluid pressure, so that the pump devices 11 to 14th results in a constant or equal volume flow for all liquids. This also ensures that an optimal droplet size for the crop protection agent application at the respective spray nozzle 4th is adjustable.

3 shows the mixing device in a schematic representation 15th . This has a mixing chamber 16 in which the different liquids can be mixed together. The mixing chamber 16 has several inlets for this purpose 17th to 21st and one to at least one of the spray nozzles 4th leading expiration 22nd .

The inlets 17th to 21st is one valve each 23 , 24 , 25th , 26th and 27 assigned, which is the flow cross-section of the respective inlet 17th to 21st can close or release. These are the valves 23 to 27 designed to be electrically controllable. In particular, the valves 23 to 27 one actuator each 23 ' , 24 ' , 25 ' , 26 ' and 27 ' for moving an adjustable valve element which can be moved against the force of a return spring. The valves 23 to 27 are in the 3 drawn simplified. The valve 23 is between the pump device 11 and the mixing chamber 16 switched, the valve 24 between the pump device 12 and the mixing chamber 16 , the valve 25th between the pump device 13 and the mixing chamber 16 and the valves 26th and 27 are each between the pump device 14th and the mixing chamber 16 switched. Through the valves 26th , 27 is thus the carrier liquid or the volume flow of the carrier liquid into the mixing chamber 16 adjustable while using the valves 23 , 24 and 25th the active ingredient liquids A, B and C are adjustable. The active substance liquids are expediently already pre-diluted with the carrier liquid in the tank 7th , 8th , 9 stored or provided via a suitable premix system.

Here are the valves 23 to 27 formed identically, and by controlling the actuators 23 ' to 27 ' by a control unit of a facility 28 the individual volume flows are combined with one another in such a way that at the outlet 22nd there is always a constant volume flow Q _tot .

In the first column of the following table, different combinations of crop protection agents A, B and C with the carrier liquid TF or corresponding switching combinations for achieving the volume flow Q _total are listed. The five columns behind it show the basic switch positions of the individual valves 23 to 27 shown. "ON" stands for a completely open valve and "OFF" for a completely closed valve: Valve 23 Valve 24 Valve 25 Valve 26 Valve 27 A + TF ON OUT OUT ON ON B + TF OUT ON OUT ON ON C + TF OUT OUT ON ON ON A + B + TF ON ON OUT ON OUT A + C + TF ON OUT ON ON OUT C + B + TF OUT ON ON ON OUT A + B + C + TF ON ON ON OUT OUT

A switching combination 26 = ON and valve 27 = OFF can alternatively be displayed using the switching combination valve 26 = OFF and valve 27 = ON.

The hydraulic resistance of the individual valves 23 to 27 are also the same due to their similar training. Thus, for the switching combinations shown in the table, one third of the total volume flow Q _{tot flows} through the respective open valves. For an application, the volume flow Q _tot is typically through a spray nozzle 4th , given. Furthermore, the concentration C ₂ , i.e. the volume of the respective component divided by the total volume in a reference element (a constant density and molar mass is assumed), of the individual pesticides A, B, C is also specified. So that the target concentration for the individual switching combinations is maintained, the plant protection agents A, B, C are diluted to a concentration C ₁ by means of the carrier liquid TF. The respective concentration C ₁ for the circuit diagram shown in the above table corresponds to three times the final concentration C ₂ .

If, for example, the total volume flow Q _{tot is set} at 3 l / min and the concentrations of the individual pesticides A, B, C are set as follows: C _2A = 0.01, C _2B = 0.02 and C _2C = 0.001, then for the individual switching combinations in the table above the following volume flows by concentrations Ci: Q _tot in l / min C _2A C _2B C _2C Q _VA in l / min Q _VB in l / min Q _VC in l / min Q _VTF1 in l / min Q _VTF2 in l / min C _1A C _1B C _1C A + TF 3 0.01 0 0 1 0 0 1 1 0.03 - - B + TF 3 0 0.02 0 0 1 0 1 1 - 0.06 - C + TF 3 0 0 0.001 0 0 1 1 1 - - 0.003 A + B + TF 3 0.01 0.02 0 1 1 0 1 0 0.03 0.06 - A + C + TF 3 0.01 0 0.001 1 0 1 1 0 0.03 - 0.003 C + B + TF 3 0 0.02 0.001 0 1 1 1 0 - 0.06 0.003 A + B + C + TF 3 0.01 0.02 0.001 1 1 1 0 0 0.03 0.06 0.003

The individual volume flow of the respective valve is used here 23 to 27 by pulse-width modulated switching of the valves 23 to 27 set. For the pulse width modulated switching, the valves are actuated by the actuators 23 ' to 27 ' switched at a specified frequency, duty cycle and / or specified switch-on time. There are the actuators 23 ' to 27 ' For example, designed as electromagnetic actuators, which allow rapid opening and closing of the valves 23 to 27 allow. Through the pulse-width modulated switching of the valves 23 to 27 ensures that a constant amount of spray liquid is discharged. Due to the advantageous design, the droplet size or the droplet size spectrum also remains the same, even if a choice is made or a change is made between the plant protection agents. This will be discussed in more detail below.

4th shows a diagram on the basis of which the pulse-width-modulated switching of the valves 23 to 27 is shown as an example within a switching cycle (100%). For this purpose, the switching position of the respective valve is between closed (0) and fully or fully open (1) over the time of the switching cycle ( 100 %) shown.

In the 4th The characteristic curve KA shown here shows the switching profile of the valve assigned to the active substance liquid A. 23 , the characteristic curve KB of the valve assigned to the active substance liquid B in the switching curve 24 , the characteristic curve KC the switching curve of the switching valve assigned to the active substance liquid C. 25th , KTF 1 the switching curve of the first valve assigned to the carrier liquid 26th and KTF 2 the switching curve of the second valve, which is also assigned to the carrier liquid 27 . The respective duty cycle is measured from the beginning of the opening process up to the final closing process. 4th shows the time sequence of the pulse-width modulated switching for different switch-on times (DC), the application of three active substance liquids.

• Zunächst wird ein Gesamtvolumenstrom, also die auszubringende Gesamtvolumenmenge festgelegt. Diese wird beispielsweise in Abhängigkeit von der gewählten Pflanzenschutzmaßnahme vorgegeben. Die vom Anwender vorgegebene Aufwandsmenge führt zu einem Sollvolumenstrom von beispielsweise 1 l/min für ein einzelnes Ventil. Anschließend werden die einzelnen Ventile wie zuvor beschrieben pulsweitmoduliert geschaltet. Der dabei über jedes einzelne aktivierte Ventil 23 bis 27 fließende Volumenstrom ist dabei gleich und gegenüber einem dauerhaft geöffneten Ventil reduziert. Dabei können die Ventile 23 bis 27 im Gleichtakt geschaltet werden oder zeitig zueinander versetzt. Es ist auch möglich, dass die Ventile in unterschiedlicher Frequenz betrieben werden. Beispielsweise können die Ventile mit einer Frequenz von 10 bis 50 Hz und einer Einschaltdauer (DC = Duty Cycle) von 50 % betrieben werden. So ergibt sich als Beispiel:

$$\begin{array}{l}{\text{Q}}_{\text{ges}}=1\text{ l/min}\text{, Zusammensetzung: A}+\text{B}+\text{TF}{\text{, Volumenströme: Q}}_{\text{VA}}=1/3\text{ l/min bei}\\ \text{DC}=50\text{\%};{\text{ Q}}_{\text{VB}}=1/3\text{ l/min bei DC}=50\text{\%};{\text{ Q}}_{\text{VC}}={\text{ 0 l/min; Q}}_{\text{VTF1}}=1/3\text{ l/min bei}\\ \text{DC}=50\text{\%};{\text{ Q}}_{\text{VTF2}}=\text{ 0 l/min;}\end{array}$$

The pulse-width-modulated circuit, in which the switch-on duration can be shorter than the switching cycle, as shown in the figure, makes it possible to measure the time-averaged volume flow through the respective valve 23 to 27 to reduce. This makes it possible to maintain the concentration C ₂ despite the specified concentration C _1x at the inlet of the associated valve 25th at the outlet of the valve 25th to change, based on the total volume. An exemplary operating procedure for the individual valves 23 to 27 can be implemented as follows:

• First, a total volume flow, i.e. the total volume to be applied, is determined. This is specified, for example, depending on the crop protection measure selected. The amount of effort specified by the user leads to a target volume flow of, for example, 1 l / min for a single valve. The individual valves are then switched with pulse width modulation as described above. This is done via each individual activated valve 23 to 27 The flowing volume flow is the same and is reduced compared to a permanently open valve. The valves 23 to 27 switched in the same mode or offset in time. It is also possible that the valves are operated at different frequencies. For example, the valves can be operated with a frequency of 10 to 50 Hz and a duty cycle (DC = Duty Cycle) of 50%. As an example:

$$\begin{array}{l}{\text{Q}}_{\text{total}}=1\text{l / min}\text{, Composition: A}+\text{B.}+\text{TF}{\text{, Volume flows: Q}}_{\text{VA}}=1/3\text{l / min at}\\ \text{DC}=50\text{\%};{\text{Q}}_{\text{VB}}=1/3\text{l / min at DC}=50\text{\%};{\text{Q}}_{\text{VC}}={\text{0 l / min; Q}}_{\text{VTF1}}=1/3\text{l / min at}\\ \text{DC}=50\text{\%};{\text{Q}}_{\text{VTF2}}=\text{0 l / min;}\end{array}$$

In the event that the concentration of an active ingredient is to be changed, for example the concentration of active ingredient A by 50%, it is important that the total volume flow Q _tot averaged over the switching cycle does not change or only changes slightly. For this purpose, it is provided in the present case to increase the volume flow of the active substance, the concentration of which is to be increased, by increasing the duty cycle to DC. At the same time, the volume flow of the other active ingredients or carrier liquids is adapted, in particular reduced.

Example for increasing the active ingredient concentration of A by 50%: $$\begin{array}{l}{\text{Q}}_{\text{total}}=1\text{l / min}\text{, Composition: A}+\text{B.}+\text{TF}{\text{, Volume flows: Q}}_{\text{VA}}=3/\mathrm{6th}\text{l / min at}\\ \text{DC}=75\text{\%};{\text{Q}}_{\text{VB}}=1/3\text{l / min at DC}=50\text{\%};{\text{Q}}_{\text{VC}}={\text{0 l / min; Q}}_{\text{VTF1}}=1/\mathrm{6th}\text{l / min at}\\ \text{DC}=\mathrm{25th}\text{\%};{\text{Q}}_{\text{VTF2}}=\text{0 l / min;}\end{array}$$

Example for reducing the active ingredient concentration of A by 50%: $$\begin{array}{l}{\text{Q}}_{\text{total}}=1\text{l / min}\text{, Composition: A}+\text{B.}+\text{TF}{\text{, Volume flows: Q}}_{\text{VA}}=1/\mathrm{6th}\text{l / min at}\\ \text{DC}=\mathrm{25th}\text{\%};{\text{Q}}_{\text{VB}}=1/3\text{l / min at DC}=50\text{\%};{\text{Q}}_{\text{VC}}={\text{0 l / min; Q}}_{\text{VTF1}}=\text{3}/\mathrm{6th}\text{l / min at}\\ \text{DC}=75\text{\%};{\text{Q}}_{\text{VTF2}}=\text{0 l / min;}\end{array}$$

As a possible alternative, carrier liquid TF can also be fed through the second valve 27 to be dosed: $\begin{array}{l}\text{Exemplary distribution of the TF volume flows}:{\text{Q}}_{\text{VA}}=1/\mathrm{6th}\text{l / min at DC}=\mathrm{25th}\%;{\text{Q}}_{\text{VB}}\\ =1/3\text{l / min at DC = 50\%};{\text{Q}}_{\text{VC}}=0\text{l / min};{\text{Q}}_{\text{VTF1}}=1/3\text{l / min at DC}=50\%;{\text{Q}}_{\text{VTF2}}=1/\mathrm{6th}\\ \text{l / min at DC}=\mathrm{25th}\%;\end{array}$

It is also conceivable to divide the carrier liquid through the valves 26th and 27 to control or influence the switching cycles of the two valves 26th , 27 over the service life of the spray device 1 are roughly the same. This can lead to failures due to too high a number of switching cycles of individual carrier fluid valves 26th , 27 be prevented.

• So ist gemäß einem weiteren Ausführungsbeispiel vorgesehen, dass zu jeder Zeit möglichst gleichzeitig drei der Ventile 23 bis 27 geöffnet sind. Dazu werden zu Beginn eines Schaltzyklus vorteilhafterweise alle Ventile 23 bis 25, die Wirkstoffflüssigkeiten zugeordnet sind, geöffnet, während die Trägerflüssigkeits-Ventile 26, 27 geschlossen bleiben. Wenn nun ein Ventil der Ventile 23 bis 25 geschlossen wird, dann wird eins der Trägerflüssigkeits-Ventile geöffnet, hierbei beispielsweise das Ventil 26. Wird das zweite Ventil der Wirkstoffflüssigkeits-Ventile 23 bis 25 geschlossen, so wird das zweite Trägerflüssigkeits-Ventil 27 geöffnet. Wir das dritte Ventil Wirkstoffflüssigkeits-Ventile 23 bis 25 geschlossen, so werden auch die beiden Ventile 26 und 27 geschlossen und die Ausbringung von Pflanzenschutzmittel beendet.

So that the total volume flow is as constant as possible, the timing of the valve switching within a switching cycle / interval is optimized as follows, even if the valves are operated at the same frequency:

• Thus, according to a further exemplary embodiment, provision is made that three of the valves at any time, if possible, simultaneously 23 to 27 are open. For this purpose, all valves are advantageously at the beginning of a switching cycle 23 to 25th , the active substance liquids are assigned, open while the carrier liquid valves 26th , 27 stay closed. If now a valve of the valves 23 to 25th is closed, then one of the carrier liquid valves is opened, here for example the valve 26th . Becomes the second valve of the drug fluid valves 23 to 25th closed, the second carrier fluid valve is closed 27 open. We the third valve drug liquid valves 23 to 25th the two valves are closed 26th and 27 closed and the application of pesticides ended.

If, according to a further exemplary embodiment, only two of the valves 23 to 25th are opened during a switching cycle, they are preferably opened at the same time at the beginning of the cycle, and at the same time one of the valves that are assigned to the carrier liquid. When the first of the two active substance liquid valves is closed 23 to 25th then becomes the next carrier fluid valve 27 open. When the second active substance liquid valve is closed, both carrier liquid valves become again 26th , 27 also closed at the same time.

In a further embodiment in which only one active substance liquid valve 23 to 25th is opened during a switching cycle, both carrier fluid valves are opened at the same time 26th , 27 open, so that three valves are open again. Becomes the drug fluid valve 23 to 25th closed again, the valves assigned to the carrier liquid are also closed 26th and 27 closed.

The advantage of this method is that pressure fluctuations at the spray nozzles 4th be avoided. This also ensures that every valve 23 to 27 is only opened and closed a maximum of once per switching cycle. The carrier fluid valve is always optimal here 26th , 27 selected, in combination with the open active substance liquid valve 23 to 25th enables the best system properties, such as the smallest possible mixing flow path, the highest possible mixing quality or the lowest possible pressure differences caused by the geometry of the mixing valve at the valve outlets of the individual inlets.

Alternatively, with only two active substance liquids, such as A and B, the total volume flow is kept constant in that two valves are always open at the same time instead of three valves. For this purpose, the concentration of the active ingredient liquid only needs to be premixed in twice the target concentration for the correct dosage on the field. Both active substance liquid valves then switched 23 to 25th , in this case 23 and 24 , are opened again at the same time at the beginning of the switching cycle. With different switch-on times (DC) of the valves 23 and 24 is used for the phase in which only one of the valves 23 , 24 is open, then only one of the carrier liquid valves 26th , 27 additionally open.

If two or more active substance liquids are actively applied per switching cycle, it is possible that the two longest switch-on times of the switched valves only differ by a few percent from one another. Due to the usual switching time for valves, the carrier fluid valve that is open for this purpose would be 27 must be closed again before it is even fully opened. To reduce the power requirement and to reduce switching cycles, and thus also to extend the service life of the valves concerned, it is therefore preferable to calculate before the start of the switching cycle whether the difference between the two longest switch-on times of the active ingredient valves at the given switching frequency and cycle duration 23 to 25th scaled to the cycle duration is shorter than the switching time for the present carrier fluid valve 26th , 27 , or a certain proportion thereof, for example 50%. If this is the case, the carrier fluid valve concerned is activated 26th , 27 not switched or opened in this switching cycle. This results in a short period of time in which the volume flow is only around two thirds of the set volume flow. However, due to the short duration, this reduced volume flow is negligible.

Alternatively, the duty cycle of the valve that has been open the longest 23 to 25th so shifted relative to the switch-on times on the time axis within a cycle that the period of time in which at the beginning of the cycle only this valve and a carrier liquid valve 26th , 27 is open is as long as the length of time that this valve and one of the carrier liquid valves towards the end of the cycle 26th , 27 are open (centering).

Another option is to adjust the switching cycles of one or more active substance liquid valves 23 to 25th such that the total error in the application rate for each of the valves 23 to 25th is minimal and at the same time conclude the switch-on times flush at the end of the switching cycle. For example, the switching cycle of the valve that is open the second longest can be used for this purpose 23 to 25th extended by half the difference and the switch-on cycle of the valve that has been open the longest 23 to 25th can be shortened by half the difference. This ensures a constant total volume flow.

In order to avoid streaking at high driving speeds and low switching frequencies, switching times are distributed within a switching cycle in such a way that, especially when the switching times of individual valves change over time, the time interval between the current switching cycle and the start of the switch-on time in the following switching cycle is as close as possible to the time interval is between the current switch-on time and the end of the switching process of the previous switching cycle. If the limits for the individual switching cycles disappear and valves limit over cycles that cannot be opened, the valves with a shorter switching duration are effectively operated with a slightly increased switching frequency, which also influences the switching process. The formation of stripes for each individual active ingredient is therefore reliably prevented.

The service life of the valves is optional 23 to 27 maximized. For this purpose, the individual switching times of a switching cycle are shifted in such a way that there is always at least one valve, in particular one valve assigned to the carrier fluid 26th , 27 , remains open beyond the limit between two switching cycles. In addition to this, this can also be done with the inclusion of the active substance liquid valves 23 to 25th are implemented whereby the sequence of the selected valves is changed with each cycle, so that the advantage for all valves, especially for the active substance liquid valves 23 to 25th results. This effectively saves one valve switching of one of the valves in each switching cycle, whereby the service life of all valves is increased by at least 20% on average, when switching all 5 valves per switching cycle by reducing to 4 valve switching per cycle. This also reduces the probability of failure.

It is also conceivable to correct a deviation of the amount of liquid dispensed from the expected amount of liquid due to flow resistance, knowing the volume flows for all individual combinations from the second table shown above, with the aid of a characteristic field, to correct the switching times so that at the end the exact correct volume amount is applied for each switching per switching cycle.

It is also possible to use the mixing device as a whole 15th to adapt the flowing volume flow, for example when cornering, to adapt an application rate to the relative speed of the nozzles above the ground, which changes as a result of the journey.

The pulse-width modulated switching of the valves 23 to 27 preferably takes place during the entire operation. Alternatively, the pulse-width-modulated switching takes place only temporarily, which results in the advantage that valves can also be used which are designed for a smaller number of switching cycles.

If only one or two active substance liquids are applied, an initial constellation can also be adapted without a pulse-width modulated operation of the individual valves by switching the active substance-carrying lines on or off, provided they carry the same active substance.

If active ingredient is previously added to the carrier liquid in the container for carrier liquid, then it is also possible that nothing more needs to be added from the individual active ingredient tanks. In such a case, all directions can be served 15th leading lines carry spray liquid with the same composition. Through the 5 Valves 23 to 27 it is then possible to calculate the spray liquid volume flow and thus the amount of active ingredient used in 5 To vary levels without having to adjust the delivery pressure. In this case, however, it is advantageous if, when the spray liquid volume flow is adjusted, the matching spray nozzle is selected by an in particular automatic nozzle changing device in order to maintain the spray characteristics.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 00/59321 [0005]

Claims (14)

Spray device (1) for dispensing liquids, in particular for agricultural purposes, with at least one spray nozzle (4) for spraying out the liquid and with at least one mixing device (15) which has at least one mixing chamber (16), the mixing chamber (16) at least one first inlet (20, 21) for a carrier liquid (TF), at least two second inlets (17-19) for different active substances (A, B, C) and at least one outlet (22) connected to the spray nozzle (4) open , each of the inlets (17-21) being assigned an actuatable valve (23-27), characterized by a device (28) which, when used as intended, switches the valves (23-27) with pulse width modulation in such a way that the sequence is independent the actuation of the valves (23-27) results in a constant volume flow. Spray device after Claim 1 , characterized in that the device (28) is designed to vary a switching frequency, a switch-on duration and / or a switch-on time of the valves (23-27) based on a switching cycle when used as intended. Spray device after Claim 1 , characterized in that the valves (23-27) assigned to the inlets (17-21) are each designed the same. Spray device according to one of the preceding claims, characterized in that each valve (23-27) is preceded by a pump device (11-14) for conveying the respective liquid, the pump devices (11-14) each being designed to provide the same conveying pressure . Spray device according to one of the preceding claims, characterized in that the mixing device (15) has three second inlets (17-19) for three different, in particular prediluted, active substance liquids (A, B, C). Spray device according to one of the preceding claims, characterized in that the mixing device (15) has two first inlets (20, 21) for the carrier liquid (TF). Method for operating a spray device according to one of the Claims 1 to 6th , characterized in that the valves (23-27) are switched with pulse width modulation in such a way that the same volume flow is always fed to one or more spray nozzles (4) through the outlet (22). Procedure according to Claim 7 , characterized in that at least two valves (23-27) are switched in synchronism or staggered in time to one another. Method according to one of the preceding claims, characterized in that at least two of the valves (23-27) are switched with the same or different frequencies. Method according to one of the preceding claims, characterized in that at least two of the valves (23-27) are switched within a switching cycle with the same or different switch-on times. Method according to one of the preceding claims, characterized in that three valves (23-27) are opened simultaneously in each switching cycle. Method according to one of the preceding claims, characterized in that at least one of the valves (23-27) is switched on beyond a switching cycle. Method according to one of the preceding claims, characterized in that the valves (23-27) are switched in such a way that when the difference in the on-time (DC), the two valves (23-25) for active substances (A, B, C ), which have the longest switch-on time (DC), scaled to the switching cycle time, is shorter than the switch-on time of a valve (26, 27) for carrier liquid that is switched within the same switching cycle, this valve (26, 27) for carrier fluid is not switched in this switching cycle. Method according to one of the preceding claims, characterized in that the valves (23-27) are switched in such a way that they have at least approximately the same switching numbers within a predeterminable time span.

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