Spray apparatus

Abstract

The present disclosure relates to spray apparatus primarily for use in agriculture, for example to apply fertilisers, crop treatments and other agricultural chemicals. The spray apparatus comprises a first fluid line for a first fluid and a plurality of spray nozzles which are arranged along the first fluid line and which comprise: an inlet for receiving the first fluid from the first fluid line; and an outlet for spraying output fluid. The apparatus further comprises multiple injection valves each of which is arranged to control flow of a second fluid from a second fluid source to at least one target nozzle of the plurality of spray nozzles; and a controller for independently controlling each of the injection valves to control flow of the second fluid to the at least one target spray nozzle whereby the apparatus is configured for spot spraying.

Description

SPRAY APPARATUS

[0001] The present disclosure relates to spray apparatus primarily for use in agriculture, for example to apply fertilisers, crop treatments and other agricultural chemicals.Background

[0002] Conventionally, an agricultural sprayer comprises a spray boom which is formed from folding sections and which has spray nozzles arranged along its length such as that described in W02008 / 149054. The nozzles may be arranged into groups which can be switched on and off by the operator or by a global positioning system (GPS) to accommodate changes in working width influenced by field shapes. Although different field shapes may be accommodated, conventional spraying technology takes a blanket approach to crop protection and typically treats an entire area of each field to make sure that no target areas are missed. This may lead to significant amounts of agricultural chemicals being applied to areas where they are not needed.

[0003] Spot spraying of target areas may be used to avoid this problem. However, it may be difficult to accurately predict how much chemical is needed for the target areas. Mixing too much chemical will lead to a disposal problem and mixing too little chemical will mean that all the target areas cannot be sprayed. The agricultural sprayer may comprise a chemical injection system, but the present applicant has recognised that known systems are not ideally suited to the requirements of spot spraying because they are typically unable to respond quickly enough. As an example, for an agricultural sprayer moving at approximately 10kph there is a reaction time of approximately 0.5 seconds from spotting a weed to spraying the weed. When the agricultural sprayer is moving more quickly, as is typical in Australia or the USA, the reaction time is even shorter.

[0004] The present applicant has recognised the need for an alternative solution which offers a targeted application of chemicals.Summary

[0005] According to a first aspect of the present disclosure, there is provided a spray apparatus as set out in independent claim 1 and a spray nozzle assembly for use in thespray apparatus as set out in the second independent claim. Further features are shown in the dependent claims.

[0006] We also describe a spray apparatus comprising: a first fluid line for a first fluid; a plurality of spray nozzles which are arranged along the first fluid line and which comprise: an inlet for receiving the first fluid from the first fluid line; and an outlet for spraying output fluid; multiple injection valves each of which is arranged to control flow of a second fluid from a second fluid source to at least one target nozzle of the plurality of spray nozzles; and a controller for independently controlling each of the injection valves to control flow of the second fluid to the at least one target spray nozzle whereby the output fluid from the at least one target spray nozzle comprises at least the second fluid.

[0007] The at least one target spray nozzle may typically output a mixture of the first and second fluids whereby the spray apparatus is configured for spot spraying. Regardless of the output from the at least one target spray nozzle, each of the other spray nozzles may continue to deliver the first fluid. In this way, a target (area or crop) may be sprayed with a mixture of the first and second fluids and outside the target, only the first fluid is sprayed. In other words, at least the first fluid is sprayed when the spray apparatus is in use.

[0008] The first fluid may be different from the second fluid. For example, the first fluid may be a base fluid and the second fluid may be a different chemical. The first fluid may be a more dilute solution of the second fluid. The first and second fluids may be a fertiliser, a weed killer or another agricultural chemical. The first and second fluids may be liquids or gases. The spray apparatus may comprise a second fluid source for the second fluid. Alternatively, the second fluid source may be external to the spray apparatus, for example, the second fluid may be air and this may be drawn from ambient air (i.e. atmospheric air) around the spray apparatus. Air (or gas) may be used to atomize the first fluid.

[0009] When the second fluid source is part of the apparatus, the second fluid source may be a tank which is connected to a second fluid line. This arrangement is similar to that for the first fluid. Alternatively, the second fluid source may comprise multiple containers each of which are connected to a respective injection valve. The sprayapparatus may comprise multiple injection lines for connecting the injection valves to the second fluid source. Each of the multiple injection lines may connect to a single spray nozzle. In other words, there may be the same number of injection lines, and hence injection valves, as nozzles. Alternatively, each injection line may connect the second fluid source to a group of spray nozzles.

[0010] Each spray nozzle may comprise a mixing chamber between the inlet and the outlet whereby the first fluid can flow into the mixing chamber. Thus, we also describe a spray apparatus comprising: a first fluid line for a first fluid; a plurality of spray nozzles which are arranged along the first fluid line and which comprise an inlet for receiving the first fluid from the first fluid line; an outlet for spraying output fluid; and a mixing chamber between the inlet and the outlet. It will be appreciated that in use the first fluid may flow through the inlet, into the mixing chamber and then out through the outlet. The spray apparatus further comprises multiple injection valves each of which is arranged to control flow of a second fluid from a second fluid source to the mixing chamber of at least one target nozzle of the plurality of spray nozzles; and a controller for independently controlling each of the injection valves to control flow of the second fluid to the mixing chamber of the at least one target spray nozzle. In use, when an injection valve is controlled to allow flow of the second fluid, the output fluid from the at least one target spray nozzle comprises a mix of the first and second fluids. It will be appreciated that when an injection valve is controlled so that there is no flow of the second fluid, the output fluid from the at least one target spray nozzle comprises the first fluid only.

[0011] Each injection valve is arranged to pump and / or meter the second fluid to the mixing chamber. Thus, the first and second fluids may be mixed in the mixing chamber before being output from the outlet. The valve may comprise a first body and a second body which is fluidly and mechanically connected to the first body, wherein the first body comprises the inlet (which may be termed a first inlet) for receiving the first fluid from the first fluid line and the outlet (which may be termed a first outlet) for spraying output fluid; and wherein the second body comprises an inlet (which may be termed a second inlet) for receiving the second fluid from the second fluid source and an outlet (which may be termed a second outlet) to the first body wherein the first fluid or a mixture of the first and second fluids may flow back into the first body and out the first outlet. The mixing chamber may be housed in the first body or the second body. The mixing chamber may be closer to the outlet than the inlet. The first body may be termed a first body section orfirst body part and the terms may be used interchangeably. Similarly, the second body may be termed a second body section or second body part.

[0012] The injection valve may be a pulse width modulation (PWM) valve. Such a PWM valve typically comprises a plunger which may be mounted within a valve chamber. The valve chamber may be termed the second body (and the terms may be used interchangeably). The plunger may be moveable between a first (typically closed) position and a second (typically open) position. In the first position, flow of the second fluid is prevented and in the second position, there is flow of the second fluid from the second fluid source to the mixing chamber. The plunger may be moved using an electric field / solenoid, compressed air and / or a spring as is known in the art. In this arrangement, each injection valve may be integrated or combined with the spray nozzle, e.g. to form a spray nozzle assembly.

[0013] In one arrangement, the plunger may divide the valve chamber into a first compartment adjacent a first end of the plunger and a second compartment at the opposite end of the plunger wherein a size of each of the first and second compartments is dependent on the location of the plunger in the valve chamber. For example, in the first position, the size of the first compartment is small relative to the size of the second compartment and in the second position, the size of the second compartment is small relative to the size of the first compartment. The first compartment may be for receiving the first fluid and the second compartment may be for receiving the second fluid. In this way, the first and second fluid may be kept separate from each other within the valve chamber.

[0014] The apparatus may further comprise a connecting line fluidly connecting the second fluid source directly or indirectly to the mixing chamber for the second fluid to flow from the second fluid source into the mixing chamber. When the second compartment is for receiving the second fluid, the connecting line may fluidly connect the compartment to the mixing chamber for the second fluid to flow from the second compartment into the mixing chamber. There may be an injection line which connects the second compartment to the second fluid source. In other words, the second fluid source is connected to the mixing chamber via the injection line, the second compartment and the connecting line. Movement of the plunger from the first to the second position may draw the second fluid into the second compartment through the injection line. Movement of the plunger from the second to the first position may pushthe second fluid along the connecting line from the second compartment to the mixing chamber. The connecting line may be external to the injection valve. Where the connecting line is external to the injection valve (e.g., in the form of pipework), the connecting line leads more directly to the mixing chamber (bypassing the first compartment). The connecting line may further comprise a non-return valve whereby the second fluid flows only from the second compartment to the mixing chamber and there is no flow of the second fluid from the mixing chamber to the second compartment.

[0015] In an alternative arrangement, the connecting line may pass through the plunger. In other words, where the connecting line passes through the plunger, the connecting line may lead to the mixing chamber, for example via the first compartment when there are first and second compartments or direct to the mixing chamber from an injection line connected to the second fluid source when the first compartment is the mixing chamber. In this direct arrangement, the second fluid source is connected to the mixing chamber via the injection line and the connecting line only. The plunger may be mounted within a channel within a solenoid which controls movement of the plunger. In this way, the connecting line is internally mounted within the valve assembly. The mixing chamber may be within the second body in this arrangement.

[0016] In both the internal and external arrangements of the connecting line, the injection valve may comprise a valve chamber and a plunger which is moveable between a first and a second position and which divides the valve chamber into a first compartment adjacent a first end of the plunger and a second compartment at the opposite end of the plunger and wherein a size of each of the first and second compartments is dependent on the location of the plunger in the valve chamber. In the first position, the second compartment has maximum volume and in the second position, the second compartment has minimum volume. Movement of the plunger from the second to the first position may draw the second fluid into the second compartment and / or the connecting line. Movement of the plunger from the second to first position may pump the second fluid from the second compartment and / or the connecting line to the mixing chamber. Particularly in the arrangement having an internal connecting line, the first compartment may also form the mixing chamber.

[0017] In these arrangements, the PWM valve may control flow of the second fluid into the mixing chamber. The PWM valve, more specifically its plunger, may be consideredto be acting as a pump or a metering device. The amount of the second fluid which is drawn into the second compartment and / or the mixing chamber may be adjusted or regulated by the stroke (i.e., length of movement) of the plunger. Thus, the controller may be further configured to control movement of the plunger to regulate flow of the second fluid into and / or out from the second compartment and / or the mixing chamber. For example, for a fixed frequency for the PWM, an open time period for which the plunger directed to the second (open) position and a closed time period for which the plunger is directed to the first (closed) position may be varied in order to control the rate of flow (in the present case, the rate of flow of the first and / or second fluid). The rate of flow may also be controlled by varying the frequency of the PWM. In the case of frequency variation, the amount of fluid pumped by the plunger acting as a pump is expected to change in proportion to the variation in the frequency. For example, it will be appreciated that increasing frequency would cause the plunger to move between the first and second positions more frequently, thereby increasing the amount of fluid pumped.

[0018] The controller may adjust the open time period and the closed time period by adjusting the on / off signal which is applied to the injection valve to control the flow of the second fluid. Alternatively, or additionally, the controller may adjust the frequency of the on / off signal which corresponds to the open / closed time period. For example, by simultaneously adjusting both the open / closed time periods and the frequency of the on / off signal, the ratio between the first fluid and the second fluid may be adjusted. Alternatively, or additionally, the flow into or out of the second compartment and / or mixing chamber may be regulated in other ways, e.g., by providing one or more orifices (pump input and / or output orifices) and adjusting second fluid pressure. The connecting line may comprise at least one non-return valve to control flow of the second fluid into / from the second compartment / mixing chamber. The at least one non-return valve may be within the connecting line, particularly when the connecting line is internal.

[0019] As described above, the injection valve may control flow of the second fluid into the mixing chamber. Additionally, the injection valve may control flow of the first fluid through the spray nozzle into the mixing chamber, for example using the first compartment and second compartment arrangement or using the mixing chamber and second compartment arrangement. In the first position of the plunger, flow of the first fluid through the nozzle may be completely prevented / blocked. Thus, the first fluid maybe prevented from flowing into the first compartment or into the mixing chamber depending on the arrangement. In the first position of the plunger, there may also be no flow of the second fluid into the mixing chamber which may also be prevented by the position of the plunger or another mechanism as described above. In the second position, there may be flow of the first fluid through the first compartment to the mixing chamber or direct into the mixing chamber when there is no first compartment which is separate from the mixing chamber. In the second position of the plunger, there may also be flow of the second fluid into the mixing chamber. In other words, the first position is an “off’ position and the second position is an “on” position. The controller may be further configured to control movement of the plunger to regulate flow of the first fluid into and / or out from the first compartment / mixing chamber. The amount of the first fluid which is drawn into the first compartment / mixing chamber may be adjusted or regulated by the stroke (i.e., length of movement) of the plunger.

[0020] The plunger may be formed from a single, integral piece / component. Alternatively, the plunger may comprise at least two separate pieces / components. By using at least two separate pieces, the two separate pieces may be controlled to move separately from one another. For example, a first piece may be moveable to control the fluid flow from the mixing chamber to the spray nozzle and a second piece may be moveable to pump / meter the second fluid into the mixing chamber. The first piece may be arranged to move more quickly than the second piece.

[0021] In an integrated arrangement which also uses injection lines, the injection line may be indirectly connected to the mixing chamber, for example via the injection valve and / or via the first fluid line. In an arrangement in which the injection line is indirectly connected to the mixing chamber via the injection valve, the injection valve may be adjacent the spray nozzle.

[0022] As an alternative to the integrated injection valve and nozzle, the injection valve may be positioned closer to the source of the second fluid than the nozzle. For example, when there is a second fluid line which is connected to a spray nozzle via an injection line, the injection valve may be positioned at an end of the injection line which is close to the second fluid line so as to control flow of the second fluid from the second fluid line into the injection line. In such an arrangement, the injection valve may be a switch to turn the flow of second fluid into the injection line on or off. Alternatively, the injection valve may be a regulating valve, e.g., a pulse width modulation valve as described above. Ineither alternative, there may be a separate valve to control flow of the first fluid through the nozzle. The injection valve may comprise a regulator to regulate flow of the second fluid into the mixing chamber. The regulator may be a second PWM valve.

[0023] As mentioned above, the spray apparatus may be for spot spraying. The controller may be configured to receive an input based on detected data; select the target at least one spray nozzle based on the input; and control each of the injection valves which are connected to the selected target spray nozzles. The detected data is one of: imaging data; geographical location data; and coordinate data relative to a reference location. The use of a PWM valve may be helpful to speed up the reaction time from spotting a weed to spraying the weed. The reaction time may be below approximately 0.5 seconds.

[0024] The adapted nozzle and PWM valve which are described above may be used in other applications than spot spraying. Thus, according to another aspect of the present techniques, there may be a spray nozzle assembly as set out in the independent claim.

[0025] We also describe a spray nozzle assembly comprising a spray nozzle which is connectable to a first fluid line of a spray apparatus and comprises: an inlet for receiving a first fluid from the first fluid line; an outlet for spraying output fluid; and a mixing chamber between the inlet and the outlet; and the spray nozzle assembly further comprises a pulse width modulation valve which is adjacent the spray nozzle and which is configured to control flow of a second fluid from a second fluid source to the spray nozzle. The PWM valve may comprise: a valve chamber; and a plunger which is located within the valve chamber and defines separate first and second compartments within the valve chamber wherein the location of the plunger within the valve chamber defines a size of each of the first and second compartments to control flow of both the first and second fluids into the mixing chamber.

[0026] Features of the spray apparatus which are described above also apply to the spray nozzle assembly. The spray nozzle assembly may further comprise an injection line connecting the second compartment to a source of the second fluid, and wherein the plunger is moveable between a first and second position whereby, in use, movement of the plunger from the first to the second position, draws the second fluid through the injection line into the second compartment and movement of the plunger from the second to first position pumps the second fluid from the second compartment to the mixingchamber. Alternatively, the plunger may be moveable between a first and second position whereby, in use, movement of the plunger from the first to the second position, draws ambient air into the second compartment and movement of the plunger from the second to first position pumps the air from the second compartment to the mixing chamber. In other words, there is no injection line in this arrangement.

[0027] The first compartment may be connectable to the mixing chamber to provide a fluid path for the first fluid to flow to the mixing chamber and the second compartment may be connected to the mixing chamber via an external connecting line to provide a fluid path for the second fluid to flow to the mixing chamber. Alternatively, the first compartment may be the mixing chamber and the second compartment may be connected to the mixing chamber via an internal connecting line to provide a fluid path for the second fluid to flow through the plunger to the mixing chamber. The injection line may be also be termed a connecting line.Brief Description of the Drawings

[0028] Examples of the present disclosure will now be described with reference to the accompanying drawings, in which:

[0029] Figure 1 is a schematic view of spray apparatus according to the present disclosure;

[0030] Figure 2a is a first arrangement for connecting first and second fluid lines to a nozzle such as those shown in the spray apparatus of Figure 1;

[0031] Figure 2b is a schematic diagram showing one method for regulating the flow of the second fluid in the nozzle of Figure 2a;

[0032] Figure 3 is an alternative arrangement for connecting first and second fluid lines to a nozzle such as those shown in the spray apparatus of Figure 1;

[0033] Figure 4 is a perspective view of a nozzle that may be used in the arrangement shown in Figure 3;

[0034] Figure 5a is a side view of a nozzle that may be used in the arrangement shown in Figure 3;

[0035] Figure 5b is a cross-sectional view along line AA of Figure 5a, and

[0036] Figures 6a and 6b are cross-sectional views of an alternative nozzle in the open and closed positions respectively.Detailed Description

[0037] Generally, the present techniques describe a spray apparatus primarily for use in agriculture, for example to apply fertilisers, crop treatments and other agricultural chemicals. The spray apparatus comprises a first fluid line for a first fluid and a plurality of spray nozzles which are arranged along the first fluid line and which comprise: an inlet for receiving the first fluid from the first fluid line; and an outlet for spraying output fluid. The apparatus further comprises multiple injection valves each of which is arranged to control flow of a second fluid from a second fluid source to at least one target nozzle of the plurality of spray nozzles and a controller for independently controlling each of the injection valves to control flow of the second fluid to the at least one target spray nozzle, more specifically to the mixing chamber whereby the apparatus is configured for spot spraying of a mix of the first and second fluids.

[0038] Figure 1 shows an agricultural crop sprayer (or spray apparatus - the terms may be used interchangeably), of the kind that can be tractor mounted or towed by a tractor. Such a spray apparatus typically comprises a spray boom (not shown) which is formed from folding sections and which has a plurality of spray nozzles 50 arranged at regular intervals along its length. The spray nozzles may also be termed spray nozzle assemblies and the terms may be used interchangeably. The nozzles 50 may be any suitable nozzle, for example an atomising spray nozzle. As is known in the art, atomisation may be achieved by the structure of the nozzle itself and also by the introduction of air into the nozzle.

[0039] Like the sprayer shown in W02008 / 149054, the spray apparatus of Figure 1 comprises a first fluid line 12 in the form of pipe-work which is connected to each spray nozzle 50 to supply each spray nozzle 50 with a first fluid. The first fluid may be stored in a tank 30 and may be pumped through the first fluid line 12 using a pump 32. Optionally, the first fluid line 12 may also be connected to a filling hopper 36 which may be used to introduce additional chemical(s) into the first fluid line to mix with the first fluidfrom the tank 30. The first fluid line may also optionally comprise a control valve 34 to control flow of the first fluid back into the tank 30. In other words, the first fluid may flow from the tank 30 to the nozzles 50 and back to the tank 30. Thus, the first fluid line may also be termed a first fluid path or a first circulation path and the terms may be used interchangeably. The first fluid may be a diluted chemical or mix of chemicals, e.g., weed killer, crop treatment or fertiliser.

[0040] In contrast to the arrangement of W02008 / 149054, the spray apparatus of Figure 1 also comprises a second fluid line 52 in the form of pipe-work which is connected to each spray nozzle 50 to supply each spray nozzle 50 with a second chemical fluid. The first fluid may be stored in a second tank 40 and may be pumped through the second fluid line 52 using a pump (not shown). A control valve 42 may be used to control flow of any second fluid which is not dispensed from the nozzles 50 back into the second tank 40. Thus, the second fluid line may also be termed a second fluid path or a second circulation path and the terms may be used interchangeably. The second fluid may be different from the first fluid. For example, the first fluid may be a base mix which is generally to be applied and the second fluid may be a different, additional chemical which is only to be applied to specific areas. Alternatively, the first and second fluids may be the same or differently diluted variations of the same chemical. For example, the second fluid may be a more concentrated version of the first fluid. Both the first fluid and the second fluid are typically under pressure in their respective fluid lines.

[0041] The spray apparatus of Figure 1 also comprises a controller 60 which controls the flow of the second fluid to each nozzle 50. Advances in application techniques now include visual systems, global positioning systems or other sensors (not shown) that can identify targets to be sprayed. These targets may include target crops or areas in fields in which crops are to be planted. When the controller 60 identifies one or more targets to which the second fluid is to be applied, for example after receiving appropriate data from the visual system, GPS system or sensors, the controller 60 determines which set of spray nozzles are to receive the second fluid so that the spray apparatus can precisely apply the second fluid to the or each identified target.

[0042] The controller 60 may then control delivery of the second fluid to the set of spray nozzles and this controlled delivery may be termed spot spraying. The set of spray nozzles may comprise some or all of the plurality of spray nozzles but is typically a relatively small sub-set (say two to ten nozzles). As described in more detail below, thereare various mechanisms for controlling delivery of the second fluid to the set of nozzles 50 and the mechanisms may comprise multiple valves which are independently controllable from each other, and which are independent from any valves controlling the flow of the first fluid in the first fluid line.

[0043] Figure 2a shows one arrangement for controlling delivery of the second fluid to one or more nozzles 50 which is mounted on the first fluid line 12 to receive the first fluid and deliver it from a nozzle outlet in a spray pattern 58. An injection line 54 connects the second fluid line 52 to an additional port on the nozzle 50. Flow from the second fluid line 52 into the injection line is controlled by an injection path valve 56. The injection line may also be termed an injection flow path. Each injection path valve 56 is opened or closed on receipt of a signal from the controller. Each injection path valve 56 is communicatively connected to the controller using any suitable means, including wireless or wired connections. The injection path valve may be any suitable valve.

[0044] It will be appreciated that the second fluid line needs to be maintained at a suitable differential pressure to the first fluid line to allow the second fluid to flow when the controller sends a signal to open the injection path valve. When the injection path valve 56 is a simple open / close valve, there may be a need for an additional mechanism to regulate the flow of the second fluid. Any suitable regulation mechanism may be used, e.g., an orifice and / or a venturi. Alternatively, a valve such as a pulse width modulation valve may be used to control the flow of the second fluid to each targeted nozzle.

[0045] A schematic example of a regulation mechanism which may be incorporated in the spray nozzle is shown in Figure 2b. The regulation mechanism comprises a venturi 64. First fluid flows through the body of spray nozzle as indicated by arrow A. The venturi comprises a section of pipework with reduced diameter compared to the rest of the pipework in the body of the spray nozzle through which the first fluid flows. The section of pipework of reduced diameter comprises a small hole through which the second fluid can flow into the nozzle as indicated by arrow B.

[0046] The fluid velocity must increase through the constriction to satisfy the question of continuity whilst its pressure must decrease due to conservation of energy and according to Bernoulli’s principle. The reverse is also true. In other words, as the first fluid passes into the narrowed section, the speed of the first fluid increases and as the first fluid passes into the following wider section, the speed of the first fluid decreases and thesecond fluid is drawn into the nozzle through the small hole. Accordingly, a mixture of the first and second fluid is then presented to the spray nozzle outlet and is output as shown by pattern 58.

[0047] Figure 3 shows an alternative arrangement for controlling delivery of the second fluid to one or more nozzles 150 which is mounted on the first fluid line 12 to receive the first fluid and deliver it from a nozzle outlet in a spray pattern 58. An injection line 154 connects the second fluid line 52 to a valve chamber in the nozzle 150. A connecting flow path / line 156 connects the valve chamber to a mixing chamber in the nozzle 150 so that the second fluid is mixed with the first fluid before delivering the mixture from the nozzle output. As explained in more detail below, flow from the second fluid line 52 into the injection line 154 is controlled by the nozzle itself. Alternatively, the injection line 154 may connect the second fluid line 52 to the first fluid line adjacent (upstream with respect to fluid flow) to the given spray nozzle 150 which is to be supplied by said injection line 154.

[0048] Figure 4 is a schematic perspective view of a nozzle assembly 150 which may be used in the arrangement of Figure 3. For simplicity, the injection line is omitted but the connecting flow path 156 is shown. The nozzle assembly 150 is an adaptation of a pulse width modulation (PWM) nozzle 150. The nozzle assembly 150 comprises a connector 158 for connecting the nozzle assembly 150 to the first fluid line, a nozzle outlet 14 through which the first fluid (a mixture of first and second fluids, or the second fluid) is dispensed, a first body 160 through which the first fluid flows from the connector 158 to the nozzle outlet 14 and a second body 162 which houses the pulse width modulation valve. As explained above, the connecting flow path 156 connects a valve chamber in the second body 162 to a mixing chamber in the first body 160. The connector 158 provides a mechanical and fluid connection to the first fluid line and comprises an inlet through which the first fluid flows into the nozzle.

[0049] Figures 5a and 5b show more detail of the nozzle assembly 150 of Figure 4 and thus the same reference numbers are used. Figure 5b is a cross-section along line AA of Figure 5a. As shown in Figure 5b, the second body 162 houses a PWM valve comprising a plunger 174 mounted in the valve chamber. The location of the plunger 174 within the valve chamber is controlled using standard techniques, e.g., spring biasing to bias the plunger in an “off” position and a mechanism, e.g. a solenoid / electric field / compressed air system / other mechanism, to move the plunger to an “on” position.The plunger 174 divides the valve chamber into a first compartment 184 which abuts a first end of the plunger and a second compartment 182 at the opposite end of the plunger. The size of each of the first and second compartments varies depending on the location of the plunger in the valve chamber. In the “on” position, the first compartment 184 has a greater volume than in the second “off” position and similarly, the second compartment 182 has a greater volume in the second “off” position than in the first “on” position.

[0050] The first body 160 comprises a first channel 170 through which the first fluid can flow from the first fluid line 12 through the first body 160 into the first compartment of the valve chamber of the second body 162 and a second channel 172 through which the first fluid can flow from the valve chamber of the second body 162 into the mixing chamber 180 of the first body 160. The injection line 154 connects the second fluid line 52 to the second compartment of the valve chamber. The connecting line 152 (e.g. pipework) connects the second compartment of the valve chamber to the mixing chamber 180 of the first body. In this arrangement, the connecting line 152 is shown as an external connecting line. However, it will be appreciated that the connecting flow path 156 provided by the connecting line 152 may also be internal to the nozzle assembly, for example through the plunger 174 (as detailed below in the example shown in Figures 6a and 6b). The connecting line may further comprise a non-return valve (shown in Figure 5b where the connecting line 152 and the injection line 154 connect to the nozzle assembly 150) whereby the second fluid flows only from the second compartment to the mixing chamber and there is no flow of the second fluid from the mixing chamber to the second compartment.

[0051] The plunger 174 is biased, for example using a spring, to prevent the first fluid flowing through the first body. In other words, the plunger 174 is biased in a first “off” position in which the first compartment 184 has no volume for receiving the first fluid. In this first position, the second compartment 182 has maximum volume and movement to the first position draws (sucks) the second fluid from the injection line 154 to fill the second compartment ready for use. In other words, the plunger 174 is acting as a pump.

[0052] The amount of the second fluid which is drawn into the second compartment may be adjusted or regulated by the stroke (i.e. length of movement) of the plunger 174. Alternatively, or additionally, the flow into the second compartment may be regulated in other ways, e.g. by providing an orifice which connects the injection line 154 to the second body and by adjusting pressure in the injection line 154 and / or second fluid line52 to regulate flow of the second fluid through the orifice into the second compartment. Such an orifice may be termed a pump input orifice.

[0053] Once activated, the plunger 174 moves to a second “on” position in which the first compartment has a maximum volume to permit flow of the first fluid and simultaneously, any second fluid which is in the second compartment is forced through the connecting line 152 to the mixing chamber. Flow of the second fluid into the mixing chamber may be regulated by stroke of the plunger 174. Alternatively, or additionally, the flow into the mixing chamber may be regulated in the same way as the flow into the second compartment. In other words, an orifice may be used to connect the connecting line 152 to the mixing chamber and the pressure of the second fluid may be adjusted to control or regulate the flow through the connecting line 152. Such an orifice may be termed a pump output orifice. In the mixing chamber, both the first and second fluids mix and are then sprayed through the nozzle outlet 14.

[0054] There may also be provided a shut-off valve (not shown) which, in a closed state, prevents the second fluid from reaching the second compartment through the injection line 154. On the other hand, in an open state, the shut-off valve permits the flow of the second fluid into the second compartment responsive to the plunger 174, as described. Accordingly, when the shut-off valve is in the closed state, the stroke of the plunger 174 may not draw any of the second fluid and only the first fluid may be sprayed from the nozzle outlet 14. For example, the controller 60 controls the shut-off valve.

[0055] In some examples, a particular scheme for controlling the plunger 174 may be used when the shut-off valve is in the closed state. For example, the plunger 174 may be moved and held slightly open (slightly away from the closed position) so that pressure in the first fluid line causes the first fluid to be sprayed from the spray nozzle. However, in this case, due to a lack of movement of the plunger 174 back and forth (in other words, there is no stroke applied to the plunger 174), there is substantially no pumping to draw the second fluid. When the shut-off valve is closed, such operation may, for example, advantageously avoid cavitation issues.

[0056] When used in a standard system, a PWM nozzle may be switched “on” and “off” many times per second to allow chemical application rates to be changed by varying the “on” time (open time period - in which the plunger is moved to the second position) in relation to the “off” time (closed time period - in which the plunger is moved to the firstposition). Additionally, as is known in the art, chemical application rates may be changed by varying the pressure at the spray nozzle outlet. This also changes the droplet size which is not always advisable. These techniques can also be used in the present system to allow both application pressure and application rate to be adjusted at each nozzle independently from the other nozzles. For example, the pulsing of the plunger 174 between the first and second positions can be used to pump the second fluid into the spray stream for the first fluid before it leaves the spray nozzle, therefore achieving almost instantaneous application of the second fluid.

[0057] In some examples, the PWM valve comprising the plunger 174 may be controlled by varying the frequency of switching between the “on” signal and the “off’ signal. In some examples, the frequency may be varied as an alternative to varying the “on” time in relation to the “off” time. In some examples, the frequency may be varied in addition to varying the “on” time in relation to the “off” time. In some examples, the frequency may be varied contemporaneously with varying the “on” time in relation to the “off” time. For example, by simultaneously adjusting both the “on” time in relation to the “off” times and the frequency, the ratio between the first fluid and the second fluid may be adjusted. Advantageously, using both the frequency and the relative on / off time periods as variables may provide for changes in ratio between the first and second fluids, as desired, without any additional stroke control schemes or other flow control features. Although, it should be noted that other such feature may still be optionally included.

[0058] Referring again to Figure 2b, in some examples, the venturi 64 may be provided between the second fluid line 52 and the nozzle assembly 150 (for example, somewhere along the 154). In some examples, the venturi 64 may be provided along the connecting line 152 before the second fluid reaches and mixes with the first fluid.

[0059] Figures 6a and 6b show an alternative nozzle assembly 250 to the one shown in Figures 4, 5a and 5b. Both Figures 6a and 6b are cross-sections along a line AA which is in a similar orientation to the line AA of Figure 5a. In the arrangement of Figures 6a and 6b, the connecting line of Figure 5b which is shown as external to the nozzle assembly is replaced with an internal connecting line 252 through the nozzle assembly 250. There are resulting changes to other components of the nozzle assembly, for example, the mixing chamber, in which the first and second fluids are mixed before dispensing from the nozzle, is in the valve chamber of the second body rather than inthe first body. In both arrangements, the mixing chamber is close to the outlet of the nozzle, specifically closer to the outlet rather than the inlet of the nozzle. Some features are unchanged, and the same reference number has been retained for the unchanged features.

[0060] The alternative nozzle assembly 250 of Figures 6a and 6b is also an adaptation of a pulse width modulation (PWM) nozzle. The nozzle assembly 250 comprises a connector 158 for connecting the nozzle assembly 250 to the first fluid line, a nozzle outlet 14 through which the fluid is dispensed, a first body 160 through which the first fluid flows from the connector 158 to the nozzle outlet 14 and a second body 262 which houses the pulse width modulation valve. The connector 158 provides a mechanical and fluid connection to the first fluid line and comprises a first inlet through which the first fluid flows into the nozzle. Similarly, as explained in more detail below, the connecting line 252 provides a mechanical and fluid connection from the second body 262 to the second fluid line. The second body 262 (and hence the connecting line) comprises a second inlet through which the second fluid flows into the nozzle.

[0061] As previously, the PWM valve is housed within the second body 262 and comprises a solenoid 276 and plunger 274 for controlling delivery of the second fluid. In contrast to the arrangement above, the solenoid 276 has a channel running centrally through the solenoid 276 and the plunger 274 is mounted within the channel. As above, the location of the plunger 274 within the channel is controlled using standard techniques. Like the previous arrangement, the plunger 274 may be considered to divide the valve chamber into a first compartment which is adjacent a first end of the plunger and a second compartment 282 at the opposite end of the plunger. In this arrangement, the second compartment 282 is also within the channel in the solenoid and the first compartment acts as the mixing chamber 280.

[0062] The connecting line 252 for connecting the nozzle to the second fluid line (not shown) comprises a channel running through the plunger 274. The connecting line 252 may optionally comprise a non-return valve 290 whereby the second fluid flows only from the second fluid line to the mixing chamber 280 and there is no flow of the second fluid from the mixing chamber back out to the second fluid line. As before, pulsing of the plunger 274 between first and second positions can be used to pump the second fluid into the spray stream for the first fluid before it leaves the spray nozzle. The frequency and the relative on / off time periods as variables may provide for changes in ratio betweenthe first and second fluids, as desired, without any additional stroke control schemes or other flow control features.

[0063] Figure 6a shows the PWM valve in an open arrangement in which both the first and the second fluid can flow through the nozzle assembly so that a mixture of the first and second fluids can be used to target a weed or crop. As described above, the first body 160 comprises a first channel 170 through which the first fluid can flow from the first fluid line through the first body 160. In this arrangement, the first fluid flows into the mixing chamber 280 of the second body 162. The second fluid flows from the second fluid line through the connecting line 252 (which passes through both the solenoid 276 and the plunger 274 within the solenoid 276) to the mixing chamber 280. There is a second channel 272 through which the mixture of first and second fluid flows from the mixing chamber 280 to the nozzle outlet 14.

[0064] As shown in Figure 6a, a second end of the plunger 274 is aligned with the end of the channel through the solenoid 276. In other words, the plunger 274 is located in an “on” position in which the second fluid can flow into the mixing chamber 280. In this example, there is an optional insert valve 284 which is housed within the second body 262 adjacent the first body 160. The insert valve 284 comprises a first channel which connects the first channel 170 of the first body 160 to the mixing chamber 280 and a second channel which connects the mixing chamber 280 to the second channel 272 of the first body. When the plunger 274 is in an “on” position, fluid can flow from the mixing chamber 280 to the nozzle outlet 14. The fluid can be the first fluid only or a mixture of the first and second fluid when the controller controls the PWM valve to allow flow of the second fluid.

[0065] Figure 6b shows the PWM valve in a closed or off arrangement in which neither fluid can flow through the nozzle assembly. As shown in Figure 6b, the plunger 274 is located in an “off” position in which the second fluid cannot flow into the mixing chamber 280. The position of the plunger 274 also blocks the outlet from the mixing chamber 280 towards the nozzle outlet 14, thus preventing any fluid flow through the second channel 272 to the nozzle outlet 14. In this arrangement, the second end of the plunger 274 is adjacent the optional insert valve 284 and may more specifically be located in a valve seat in the optional insert valve 284. The plunger 274 may be biased, for example using a spring, in this “off” position. In other words, the plunger 274 is biased in a first “off”position in which there is no first or second fluid flow through the nozzle. Once activated, i.e. when switching from the “off’ to the ”on” position, the plunger 274 moves to the second “on” position in which the mixing chamber has a maximum volume to permit mixing of the first and second fluids and subsequent discharge of the mixed fluids through the second channel 272 and out through the nozzle outlet 14. In the “off” position, the second compartment 282 has maximum volume. In other words, in the “on” position, the mixing chamber (first compartment) has a greater volume than in the second “off” position and similarly, the second compartment has a greater volume in the first “on” position than in the second “off” position.

[0066] In this arrangement, the PWM valve may be configured to pump the second fluid into the mixing chamber as described above. However, as shown in Figures 6a and 6b, the plunger 274 may be adapted, e.g. by using flats or similar components, to allow fluid to pass either side of the plunger 274. In this way, the fluid in the valve chamber is in balance. In other words, the second compartment 282 may not be used to pump the second fluid.

[0067] Figures 6a and 6b show an optional switch mechanism 286 which may additionally be used to control the flow of the second fluid through the connecting line 252 through the plunger 274 into the mixing chamber 280. This may be particularly useful when the PWM valve in the valve chamber is not used to pump the second fluid. The switch mechanism 286 may comprise a second PWM valve which is used to pump / meter second fluid flow into the mixing chamber 280 when the first PWM valve is in an “open” position as shown in Figure 6a. There may be a non-return valve 292 within the switch mechanism 286, for example within the solenoid when a PWM valve is used as the switch mechanism. When the non-return valve 292 is open, there is flow through the second fluid line into the mixing chamber but the non-return valve prevents flow from the mixing chamber to the second fluid line. This second non-return valve may be termed a shut-off valve. The switch mechanism 286 may be “on” (i.e. the valve may be “open”) when the plunger is in the “on” position. In other words, the switch mechanism may be “on” for the duration of the time that that second fluid is needed.

[0068] When the switching mechanism is “on”, the second fluid may flow from the connecting line 252 to the mixing chamber 280. This flow of second fluid may occur as a result of pressure difference, when the fluid in the mixing chamber is at lower pressure than the fluid within the second fluid line. This may be referred to as metering the secondfluid into the mixing chamber 252. Volume of the second fluid into the mixing chamber could be adjusted by orifice size and pressure difference between the first and second fluids. Alternatively, or simultaneously, any second fluid which is in the connecting line 252 may be forced (pumped) to the mixing chamber by the movement of the plunger 274 from the first “off’ position to the second “on” position. By contrast, movement from the second to the first position may draw (suck) the second fluid from the second fluid line into the connecting line 252 ready for use. In this way, the volume of the second fluid which is injected into the mixing chamber may be adjustable by the frequency of the plunger movement. As another alternative the second PWM valve may comprise a plunger which divides a valve chamber into a first and second compartment so that the plunger movement draws the second fluid from the second fluid source into the second compartment and then pushes the second fluid into the first compartment as described above. The first and second compartments may be separated by seals, e.g. along a smaller part of the plunger, so that the fluid is kept separate within these compartments. The first compartment is connected to the first PWM valve to provide the second fluid into the PWM valve when required. The second compartment may be adjacent the nonreturn valve.

[0069] In each of the arrangements shown above, there is an individual injection line connecting each nozzle separately to the second fluid line 52 and one or more valves may be used to control flow in the individual injection lines. It will be appreciated that there may be fewer injection lines with each injection line connecting the second fluid line 52 to a group of nozzles, for example a small number of nozzles such as three, four or five nozzles.

[0070] An adapted PWM nozzle described in Figures 5a and 5b or Figures 6a and 6b may also be used to pump other fluids such as high-pressure air for a twin fluid nozzle such as that described in W02008 / 149054. In such an adaptation, the connecting line is connected between the second compartment and a location which atomises the first fluid as it exits the nozzle through the nozzle outlet. As explained in W02008 / 149054, the high-pressure air must be reduced to low pressure (typically 0 to 2 bar) for the atomisation and this may be done using any suitable technique, for example a restrictor such as that shown in Figure 2b. Alternatively, the injection valve may draw ambient air from around the valve into the second compartment.

[0071] In the arrangements described above, the at least one target spray nozzle may typically output a mixture of the first and second fluids and the other spray nozzles which are not targeted continue to output the first fluid. In this way, the spray apparatus is configured for spot spraying using the at least one target spray nozzle. It will be appreciated that the arrangements described above may be adapted so that the at least one target spray nozzle may output only the second fluid. In other words, the flow of the first fluid to the at least one target spray nozzle may be stopped when the second fluid is being output, e.g. to target a weed with a very concentrated fluid. The flow of the second fluid through the at least one target nozzle may then be stopped again when normal spraying of only the first fluid is desired.

[0072] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0073] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0074] In the above description, various specific examples are described. The invention is not restricted to the details of the foregoing example(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. A spray apparatus comprising: a first fluid line for a first fluid; a plurality of spray nozzles which are arranged along the first fluid line and which comprise: an inlet for receiving the first fluid from the first fluid line; an outlet for spraying output fluid; and a mixing chamber between the inlet and the outlet; multiple injection valves each of which is arranged to control flow of a second fluid from a second fluid source to the mixing chamber of at least one target nozzle of the plurality of spray nozzles; and a controller for independently controlling each of the injection valves to control flow of the second fluid to the mixing chamber of the at least one target spray nozzle whereby, when an injection valve is controlled to allow flow of the second fluid, the output fluid from the at least one target spray nozzle comprises a mix of the first and second fluids.

2. The apparatus according to claim 1 , wherein the injection valve is a pulse width modulation valve.

3. The apparatus of claim 1 or claim 2, wherein the at least one target nozzle further comprises a connecting line which connects the second fluid source to the mixing chamber of the at least one target spray nozzle.

4. The apparatus of claim 3, wherein the injection valve comprises a valve chamber and a plunger which is moveable between a first and a second position, whereby in the first position flow of the second fluid to the mixing chamber is prevented and in the second position, there is flow of the second fluid to the mixing chamber.

5. The apparatus of claim 3, wherein the plunger divides the valve chamber into a first compartment adjacent a first end of the plunger and a second compartment at the opposite end of the plunger andwherein a size of each of the first and second compartments is dependent on the location of the plunger in the valve chamber and whereby, in use, movement of the plunger from the first to the second position, draws the second fluid into the second compartment and movement of the plunger from the second to first position pumps the second fluid from the second compartment to the mixing chamber of the at least one target spray nozzle.

6. The apparatus of claim 5, wherein the controller is configured to control movement of the plunger to regulate the flow of the second fluid into and / or out from the second compartment.

7. The apparatus of claim 5 or claim 6, further comprising one or more regulators to regulate flow of the second fluid into and / or out from the second compartment.

8. The apparatus of any one of claims 4 to 7, wherein the connecting line is external to the valve chamber.9 The apparatus of claim 4, wherein the connecting line passes through the plunger.

10. The apparatus of claim 9, further comprising at least one non-return valve in the connecting line to control flow of the second fluid into the mixing chamber.

11. The apparatus of any one of claims 4 to 10, wherein the controller is configured to control movement of the plunger to regulate the flow of the first fluid.

12. The apparatus of any one of claims 3 to 11 , wherein each injection valve is integrated with a respective spray nozzle.

13. The apparatus of any one of claims 1 to 11 , wherein the injection valve is positioned close to a source of the second fluid.

14. The apparatus according to any one of the preceding claims, wherein each of the multiple injection valves connects to a single spray nozzle.

15. The apparatus according to any one of the preceding claims, wherein the first fluid is different from the second fluid.

16. The apparatus according to claim 15, wherein the second fluid is air and each injection valve is arranged to draw air into the injection valve and then to pump the air to at least one nozzle.

17. The apparatus according to claim 15, wherein the spray apparatus further comprises a second fluid source for the second fluid; and multiple injection lines, wherein each injection line connects at least one injection valve to the second fluid source.

18. The apparatus according to claim 17, wherein the second fluid source comprises a second fluid line which is connected to each of the multiple injection lines.

19. The apparatus according to any one of the preceding claims wherein the controller is configured to: receive an input based on detected data; select the target at least one spray nozzle based on the input; and control each of the injection valves which are connected to the selected target spray nozzles.

20. The apparatus according to claim 19, wherein: the detected data is one of: imaging data; geographical location data; and coordinate data relative to a reference location.

21. A spray nozzle assembly for use in the spray apparatus of any one of claims 1 to 20, wherein the spray nozzle assembly comprises: a spray nozzle which is connectable to a first fluid line of a spray apparatus and comprises: an inlet for receiving a first fluid from the first fluid line; an outlet for spraying output fluid; anda mixing chamber between the inlet and the outlet; and a pulse width modulation valve which is adjacent the spray nozzle and which is configured to control flow of a second fluid to the spray nozzle, wherein the PWM valve comprises: a valve chamber; and a plunger which is located within the valve chamber r; and which is moveable between a first and a second position, whereby in the first position flow of the second fluid to the mixing chamber is prevented and in the second position, there is flow of the second fluid to the mixing chamber. whereby when the pulse width modulation valve is controlled to allow flow of the second fluid, the output fluid from the outlet of the spray nozzle comprises a mix of the first and second fluids.

22. The spray nozzle assembly according to claim 21 , wherein the plunger defines separate first and second compartments within the valve chamber and wherein the location of the plunger in the first and second positions defines a size of each of the first and second compartments to control flow of both the first and second fluids into the mixing chamber.

23. The spray nozzle assembly according to claim 22, wherein the plunger is moveable between a first and second position and whereby, in use, movement of the plunger from the first to the second position, draws ambient air into the second compartment and movement of the plunger from the second to first position pumps the air from the second compartment to the mixing chamber.

24. The spray nozzle assembly according to claim 22, further comprising an injection line connecting the second compartment to a source of the second fluid, and wherein the plunger is moveable between a first and second position whereby, in use, movement of the plunger from the first to the second position, draws the second fluid through the injection line into the second compartment and movement of the plunger from the second to first position pumps the second fluid from the second compartment to the mixing chamber.

25. The spray nozzle assembly according to claim 24, wherein the first compartment is connected to the mixing chamber to provide a fluid path for the first fluid to flow to the mixing chamber and the second compartment is connected to the mixing chamber via an external connecting line to provide a fluid path for the second fluid to flow to the mixing chamber.

26. The spray nozzle assembly according to claim 21 , further comprising an internal connecting line to provide a fluid path for the second fluid to flow through the plunger to the mixing chamber.

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