Spray nozzle, and also spray boom provided therewith

Spray nozzle for a spray boom to be fixed to a crop protection machine or the like. The spray nozzle is fixed on a supply line for spraying a fluid. The spray nozzle consists of a spray nozzle holder and a spray nozzle head. The passage of the inflow aperture to the outflow channel is regulated by means of an electromagnetic coil. Each spray nozzle holder can be controlled individually in a very accurate manner by means of such an electromagnetic shut-off valve situated in the spray nozzle holder. Connection between electric coil and spray nozzle holder is achieved by means of a connecting piece.

BACKGROUND OF THE INVENTION
 The present invention relates to a spray nozzle for spraying liquids.
 Such a spray nozzle is generally known in the prior art. It is used on, for
 example, a spray boom. European Patent Application 0,373,034 describes a
 method for applying a certain pattern to the ground by a series of
 electrically operable spray nozzles. Various other control means for
 controlling the passage of a fluid such as nutrients and crop protection
 products are known in the prior art. The simplest design is a manually
 operated, electrical or pneumatic valve which is fitted in the spray boom.
 It controls all or a number of spray nozzles. Environmental considerations
 and the waste involved mean that this is no longer the optimum solution.
 For the fact is that after such a valve has been taken into the
 switched-off position the downstream spray nozzles can still drip.
 Besides, with this design it is not possible to control the spray nozzles
 separately, which can be important if a piece of land extends at an angle
 relative to the direction of movement of the spray boom.
 A first proposal for overcoming this problem is to fit a pneumatic
 piston-cylinder in the spray nozzle holder. In this case the piston
 operates a diaphragm which in the unexcited state provides for a shut-off
 in the passage from the supply line to the spray nozzle head in the spray
 nozzle holder. This means that it is possible in principle to control each
 spray nozzle head separately. However, there are at least two
 disadvantages involved in such a construction. First, the control by means
 of a diaphragm is relatively sluggish, which is of minor importance if
 large quantities of fluid have to be sprayed, but if very small quantities
 have to be dispensed for a short period, it does play an important role.
 Besides, an extremely large number of components is necessary for separate
 control. For such separate control will in the first instance be on the
 basis of electrical signals, which electrical signals have to be converted
 into pneumatic signals. Moreover, a separate compressor has to be fitted
 on the crop protection machine, or has to be present elsewhere.
 SUMMARY OF THE INVENTION
 The object of the present invention is to avoid these disadvantages and to
 provide a spray nozzle which can be driven electrically, but in the case
 of which a spray nozzle can also be produced in a simple manner, using
 existing components as far as possible. In other words, an electrically
 operable spray nozzle can be the characterizing part of claim 1.
 The invention can be achieved by combining existing spray nozzles which are
 suitable for hydraulic use with an electric coil, and interposing a
 connecting piece. In an advantageous embodiment, said connecting piece can
 be provided with a pipe section which abuts the outflow aperture in a
 sealing manner at the position of that common face, and which is connected
 to the valve chamber.
 In an embodiment in which large quantities of fluid have to be displaced,
 the outflow aperture can comprise a main and auxiliary outflow channel. In
 such a case the electromagnetic valve acts as the control valve, i.e. by
 operation of this valve a further valve, and in particular a diaphragm
 valve, is controlled.
 The embodiments described above are embodiments which in the unexcited
 state of the electromagnetic coil provide a shut-off. Of course, it is
 possible to design the device the other way round, i.e. in the unexcited
 state the passage to the spray nozzle head is opened.
 With the construction described above, it is no longer necessary to
 incorporate valves in the supply line, and it is also possible to control
 the spray nozzles individually. Furthermore, the time during which the
 various spray nozzles are active can be varied over a spray boom. This can
 be important if, for example, in the case of a piece of land to be treated
 the direction of movement of the spray boom is at an angle relative to the
 boundary of the piece of land. Another exemplary application is that in
 which the conditions over the entire area of the piece of land concerned
 are not the same, i.e. at certain points fluid has to be applied and at
 other points less or no fluid at all has to be applied. The above can also
 depend on the crops present in that place, and can be regulated by means
 of sensors, possibly combined with GPS and D-GPS and a control system
 fitted specially for the purpose.
 With the current techniques it is possible to use extremely low-capacity
 electromagnetic coils. A value of 4, 5 or 8 watts has been found possible,
 so that the total power consumption of a spray boom with several dozen
 spray nozzles is relatively low.
 The invention also relates to a spray boom provided with the spray nozzles
 described above.
 It is possible to incorporate a return line or continuous recirculation
 line for fluid in the above spray boom.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 FIG. 1 shows a tractor 1 which is provided near the rear side with a bearer
 2 on which a spray boom 3 is fixed, in the usual manner. The crop
 protection machine consists of a container 7a for fluid, which is conveyed
 by way of a supply line 7 to various spray nozzles 5, 6. In this case
 spray nozzle 6 is a so-called edge nozzle, i.e. the spray profile does not
 extend beyond the end limit of spray boom 3. Spray boom 3 is suspended
 from a cable 4 or the like. It is not shown in FIG. 1 that a return line
 may be present for conveying fluid from the supply line 7 back to
 container 7a, in order in this way to avoid effects of air during starting
 and the like and to improve bringing to concentration or flushing. Tractor
 1 also has a control 9 which is connected by means of cables (not shown)
 to the spray nozzles 5 and 6.
 FIG. 2 shows a first exemplary embodiment of a spray nozzle. The spray
 nozzle indicated by 5 is fixed on supply line 7. Said spray nozzle
 consists of a spray nozzle holder 8, which is provided with an inlet 10
 projecting slightly into supply line 7. The seal is achieved by part 11.
 Spray nozzle head 12 is fixed on holder 8. It should be understood that
 any type of spray nozzle head can be used. Moreover, instead of the spray
 nozzle holder/spray nozzle head described here, it is also possible to use
 a device consisting of a number of spray nozzle heads which are fitted by
 means of a revolver-type construction on the spray nozzle holder, so that
 the correct spray nozzle head can be selected depending on the conditions
 in which spraying has to be carried out and the fluid which has to be
 sprayed.
 The spray nozzle holder 8 and spray nozzle head 12 are conventional,
 commercially available components. Spray nozzle holder 8 is provided with
 a flange 27 for the accommodation of a connecting piece 13. Spray nozzle
 holder 8 and connecting piece 13 can be fixed to each other by means of a
 union nut 14. An armature housing 17 is screwed into connecting piece 13,
 over which armature housing a coil 15 is pushed. Coil 15 consists of a
 winding 16 which is electrically connected to control 9. Inside armature
 housing 17 is an armature 19 which can move to and fro. A spring 18 is
 present, which spring drives said armature to the left in the unexcited
 state. Armature 19 is provided with a sealing face 20 at the free end.
 Spray nozzle holder 8 is provided with an inflow channel 23, which by way
 of a number of supply channels 24 fitted in a circle opens out into a
 valve chamber 25. From there, a centrally situated outflow aperture 26
 extends through a pipe section 29, which outflow aperture opens out into
 outflow channel 22 which is in communication with spray nozzle head 12.
 Seal 20 of armature 19 is designed to interact with the valve seat 21.
 On excitation of coil 15, armature 17 will move to the right and the fluid
 can flow unimpeded out of supply line 7 to spray nozzle head 12. If
 closure is desired, particularly rapid closure of aperture 26 can be
 obtained by no longer exciting the coil. No subsequent dripping is found.
 Coil 15 can have a relatively low power consumption in the excited state,
 such as 4, 5 or 8 watts. All kinds of spray patterns can be achieved by
 means of the control. In particular, any desired pattern can be achieved
 near the end of the spray boom by interaction of the edge spray nozzle 6
 with the adjacent spray nozzle 5. Furthermore, selective spraying is
 possible, and the number of components is relatively small. In particular,
 owing to the extremely high switching speed, spraying per plant is now
 achievable, i.e. the spray does not fall between two plants.
 FIG. 3 shows a variant of the construction shown in FIG. 2. This spray
 nozzle is indicated in its entirety by 30. The spray nozzle holder is
 indicated by 8, as in FIG. 2, because it is largely identical. Differences
 exist only as regards the control section and the connecting piece 28.
 This embodiment is designed in such a way that in the normal unexcited
 state of winding 16 a free passage opening is present between supply line
 7 and spray nozzle head 12.
 This is achieved by the fact that armature 32 is provided with a ring 33
 which is immovably connected thereto and is under the influence of a
 spring 31. In the unexcited state, armature 32 will be moved to the left,
 as shown in FIG. 3, and valve chamber 34 will be opened, thereby providing
 a communication by way of bypass line 35 between inflow channel 23 and
 outflow channel 22. In this construction also, use can be made of existing
 spray nozzle holders and spray nozzle heads respectively.
 FIG. 4 shows a construction which is suitable in particular for dispensing
 large quantities of fluid. This spray nozzle is indicated in its entirety
 by 40 and consists of a spray nozzle holder 39. A relatively large union
 nut 41 is fitted on the connecting piece thereof, for the accommodation of
 connecting piece 36. Apart from coil 16, a diaphragm 45 loaded by a spring
 46 is also present, shutting off the main aperture between inflow channel
 43 and outflow channel 44. Inflow channel 43 is connected to a calibrated
 control channel 47, which by way of inlet channel 48 and valve chamber 49
 is in communication with main outflow channel 52 with larger passage. In
 the manner shown in FIG. 1, an electromagnetic coil is present, consisting
 of winding 16, spring 18 and armature 19. In the unexcited state,
 auxiliary outflow channel is closed. This is caused by the fact that
 spring 18 drives armature 19 into the closed position. Owing to the small
 surface of armature 19 which is exposed to the fluid pressure acting in
 supply line 7, it is possible with a relatively light spring to ensure
 closure of the plunger even at higher pressures. Diaphragm 45 is kept
 closed by the combined action of the fluid pressure and spring 46. If
 excitation is then provided, fluid will move through the auxiliary flow
 channel to spray nozzle head 12. Owing to the fact that the aperture of
 the calibrated control channel 47 is smaller than the aperture of the
 auxiliary outflow channel 52, fluid will be discharged at a more rapid
 rate than its rate of inflow. This causes the pressure at the right-hand
 side of the diaphragm 45 to drop, and the diaphragm can open against the
 action of spring 46. The surface exposed to the pressure in the supply
 line consequently increases further, and the valve will remain opened so
 long as armature 19 makes discharge of fluid possible, with the result
 that spray nozzle head 12 will spray the medium.
 It is, of course, clear that the construction shown in FIG. 3, which in the
 unexcited state is opened, can also be used for the construction shown
 with reference to FIG. 4.
 Although the invention is described above with reference to a preferred
 embodiment, it will be understood that numerous variants thereof are
 possible without going beyond the scope of the present application.
 As indicated above, it is possible to achieve an embodiment of the spray
 nozzle holder which is particularly suitable for electromagnetic
 operation, in which case then new moulds for the injection moulding work
 are necessary.
 These and other proposals are considered to lie within the scope of the
 appended claims.