Spraying system comprising a nozzle holder having a vibration sensor

Abstract

The present invention relates to a spraying system for an agricultural sprayer, comprising a spray boom having a nozzle holder (5) comprising a body (50) housing an inlet pipe for the product to be sprayed configured to be supplied with the product to be sprayed, a nozzle (1) of said product comprising an outlet orifice of said product and configured to be supplied with product by the inlet pipe and to convey said product to said outlet orifice, vibration sensor (2); said boom being configured to spray product by said nozzle (1); said sensor (2) being configured to measure the vibrations of the body (50), said spraying system further comprising a calculation unit configured to compare the measurement of the vibrations with a reference signal to determine the state of obstruction of said nozzle (1). Abstract figure: Figure 1

Description

Title of the invention: Spraying system comprising a nozzle holder comprising a vibration sensor Technical field

[0001] The present invention relates to the field of agricultural spraying systems. More specifically, the invention relates to a spray boom, comprising at least one spray nozzle and a vibration sensor measuring the vibration of a fluid passing through said nozzle. STATE OF THE ART

[0002] An agricultural spray boom generally comprises nozzle holders distributed uniformly over the entire length of the spray boom, for spraying plant protection product on rows of plants, in liquid form or liquid fertilizer for example. In particular, such a known spray boom is designed to spray liquid on the field.

[0003] As is known, a spray bar thus comprises a plurality of nozzles spaced apart from each other, said spacing being fixed and the nozzles allowing double or even triple coverage of the surface sprayed by the liquid. A known spray bar allows spraying of the entire field, rather than spraying in a line.

[0004] The sprayed plant protection product has a certain viscosity as well as a mass of suspended deposit during spraying. Thus, the spray nozzles can, during spraying, become totally or partially blocked, preventing spraying, or at least its homogeneity, by preventing the spraying of certain areas of the rows of plants or by inducing restricted spraying.

[0005] Furthermore, the risk of at least partial obstruction of the spray nozzles causes significant stress for the user who must check throughout the spraying that the spray nozzles are functioning correctly in order to guarantee good spraying, in particular by turning around frequently to observe the spraying state of the nozzles in order to quickly detect any obstructed spray nozzle.

[0006] The invention aims to resolve the aforementioned drawbacks of the prior art, in particular by proposing a spray bar comprising at least one nozzle holder making it possible to measure the condition of the nozzles, i.e. whether they are spraying correctly or whether they are obstructed, at least partially, and to warn the user when this is the case. PRESENTATION OF THE INVENTION

[0007] More specifically, the invention relates to a spraying system for an agricultural sprayer, comprising a spray boom having a main conduit and at least one nozzle holder connected to the main conduit. The nozzle holder comprises a body housing an inlet conduit for the product to be sprayed, configured to be supplied with product to be sprayed by said main conduit. The nozzle holder comprises at least one first nozzle for spraying said product, comprising at least one outlet orifice for said product and configured to be supplied with product by the product inlet conduit and to convey said product to said outlet orifice. The nozzle holder comprises at least one vibration sensor and housed in said body or connected to said first nozzle. Said spray boom is configured to spray product through said first spray nozzle, said vibration sensor being configured to measure the vibrations of the body.Said spraying system further comprises a calculation unit configured to compare the measurement of the vibrations of the body or of the first nozzle to a reference signal to determine the state of obstruction of said nozzle.

[0008] The product to be sprayed is conveyed from the main conduit to the nozzle outlet via the nozzle holder inlet pipe. When the spray nozzle that sprays the product is partially obstructed, disturbances are generated in the product flow, causing vibrations in the nozzle holder body. The vibration sensor then makes it possible to measure the vibrations generated in the body and compare them to a reference signal. When the vibrations generated are greater than the reference signal, the nozzle is partially blocked. When the vibrations tend towards zero, the nozzle is completely blocked. The spraying system therefore makes it possible to inform the user of the nozzle blockage status without having to constantly turn towards the nozzles and check whether each nozzle is correctly spraying the plant protection product.

[0009] Advantageously, the vibration sensor is a piezoelectric sensor.

[0010] Advantageously, the vibration sensor is housed in the body of the nozzle holder, at surroundings of the outlet orifice of said nozzle.

[0011] This location as close as possible to the nozzle outlet orifice allows the most precise measurement possible of the vibrations of the body and in particular of the noise generated by the exit of the product to be sprayed through the nozzle outlet orifice.

[0012] Advantageously, the vibration sensor is further configured to transform the vibration measurement into an electrical signal.

[0013] Advantageously, the vibration sensor is further configured to transform the electrical signal into a differential signal.

[0014] Advantageously, said vibration sensor is configured to send the signal, possibly differential, to the calculation unit which is configured to compare said signal to a predetermined threshold signal.

[0015] Advantageously, the nozzle holder comprises a plurality of spray nozzles, the vibration sensor being configured to measure the vibrations of the body of each of the nozzles and to determine the state of obstruction of each of the nozzles.

[0016] Advantageously, the nozzle holder comprises a plurality of spray nozzles, a vibration sensor being connected to each of the nozzles and being configured to measure the vibrations of each of the nozzles and determine their state of obstruction.

[0017] Advantageously, the spraying system comprises a vibration amplification device located upstream of the outlet orifice of the spray nozzle, said amplification device being configured to amplify the vibrations of the body or the nozzle.

[0018] Such amplifier devices make it possible to increase the vibrations of the body when the spray nozzle becomes clogged. Thus, the measurement by the vibration sensor is more certain.

[0019] According to a first variant, the amplification device comprises propellers comprising blades configured to rotate in the product to be sprayed, so as to disturb the flow of product to be sprayed passing through the nozzle.

[0020] Thus, the flow of liquid passing through the nozzle vibrates more than if it had not been disturbed and therefore generates more vibration and therefore noise. The sensor therefore measures greater vibrations.

[0021] According to a second variant, the amplification device comprises protrusions projecting from the walls of the body, in the direction of the product to be sprayed which passes through it and configured to disturb said product.

[0022] The protrusions are configured to deflect the flowing spray material in several directions and thus to disturb it so as to increase the vibrations in the body and thus increase the noise generated.

[0023] Advantageously, the spraying system further comprises a second sensor configured to measure the surrounding noise of the spraying system, so that the measurement made by the vibration sensor can be compared to the measurement made by said second sensor.

[0024] According to another aspect of the invention, it relates to a method for detecting the obstruction of at least one nozzle of a spraying system as previously described, comprising at least the following steps: • a step consisting of passing the product to be sprayed through an orifice of said nozzle; • a step of measuring the vibrations of the nozzle body using a vibration sensor; • a step consisting of transforming the vibration measurement into a signal electric; • an optional step consisting of transforming said amplified electrical signal into a differential signal, by means of a card integrated into said vibration sensor; • a step consisting of transporting said electrical signal, where appropriate transformed into a differential signal, to a calculation unit of the spraying system; • a step consisting of comparing said electrical signal, where appropriate transformed into a differential signal, transported to a reference signal.

[0025] The method according to the invention may further comprise a step for measuring the surrounding noise, before or after the step of passing the product to be sprayed through an orifice of the nozzle, the measurement of the surrounding noise being filtered from the measurement of the vibrations of the body of the nozzle.

[0026] Advantageously, a step consisting of amplifying the electrical signal is inserted between said step consisting of transforming the measurement of the vibrations into an electrical signal and said step consisting of transforming said amplified electrical signal into a differential signal, by means of a card integrated into said vibration sensor.

[0027] According to a first embodiment, the reference signal is a predetermined threshold value pre-recorded in said calculation unit.

[0028] When the measured noise is greater than the predetermined threshold value, then the nozzle is partially obstructed. When the measured noise tends towards zero, the nozzle is completely obstructed.

[0029] According to a second embodiment, the reference signal corresponds to a calibrated threshold signal at the start of said at least one spray nozzle.

[0030] In this embodiment, the noise measured by the sensor is compared to a calibrated threshold signal. When the measured noise is greater than the calibrated threshold signal, then the nozzle is partially obstructed. When the measured noise tends towards zero, the nozzle is completely obstructed.

[0031] According to a third embodiment, the spray bar comprises a plurality of spray nozzles and in which the reference signal corresponds to an average of the electrical signals, where appropriate transformed into differential signals, transported from the other spray nozzles.

[0032] In this embodiment, the noise measured by the sensor is compared to an average of the noise generated by the other nozzles of the spray bar. When the measured noise is higher than the average of the other nozzles, then the nozzle is partially obstructed. When the measured noise tends towards zero, the nozzle is completely obstructed. PRESENTATION OF THE FIGURES

[0033] The invention will be better understood on reading the following description, given solely by way of example, and referring to the appended drawings given by way of non-limiting examples, in which identical references are given to similar objects and in which:

[0034] [Fig.l] is a schematic perspective representation of a nozzle holder according to the invention, comprising a main conduit to which the body of the nozzle holder comprising four spray nozzles and at least one vibration sensor is connected;

[0035] [Fig.2] is a left-hand schematic representation of the nozzle holder of [Fig.l] with a cover removed from the nozzle holder body, revealing the vibration sensor circuit board; and

[0036] [Fig. 3] is a flowchart illustrating the method for detecting the obstruction of at least one nozzle of the nozzle holder of the spray bar of [Fig. 1].

[0037] It should be noted that the figures set out the invention in detail to enable the invention to be implemented; although not limiting, said figures serve in particular to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0038] The invention relates to a system for spraying a plant protection product for an agricultural sprayer. In particular, the product to be sprayed is in the form of a liquid or liquid fertilizer with a certain viscosity. A mass of suspended deposit may form during spraying.

[0039] The spraying system, as shown in Figures 1 and 2, comprises a spray bar.

[0040] The spray boom is configured to spray phytosanitary product on rows of vegetation.

[0041] The spray bar comprises a main conduit 4 and at least one nozzle holder 5 connected to the main conduit 4.

[0042] The nozzle holder 5 comprises a body 50 housing an inlet pipe for the phytosanitary product to be sprayed. The inlet pipe is configured to be supplied with product by the main pipe 4.

[0043] The nozzle holder 5 further comprises at least one first nozzle 1, advantageously a plurality of nozzles 1, comprising a product outlet orifice and configured to be supplied with product via the product inlet pipe and to convey it to the outlet orifice.

[0044] With reference to [Fig.l], the nozzle holder 5 here comprises four spray nozzles 1.

[0045] The nozzle holder 5 comprises at least one vibration sensor 2. The vibration sensor 2 is housed in the body 50 of the nozzle holder 5.

[0046] The nozzle holder 5 comprising a plurality of nozzles 1 may comprise a sensor at level of each orifice of each of the nozzles.

[0047] The vibration sensor 2 comprises at least one electronic card 3. The electronic card 3 is housed in the body 50 of the nozzle holder 5.

[0048] According to a variant not shown, the electronic card can be offset from the body 50 of the nozzle holder 5.

[0049] In particular, the body 50 of the nozzle holder 5 has a chamber 51, the side walls of which delimit an opening. Through said opening is introduced the sensor 2, which is connected to the body 50. The chamber 51 is closed by a cover 52, visible in [Fig.l]. In [Fig.2], the cover 52 has been removed, so as to make the sensor 2 visible.

[0050] The sensor 2 is configured to measure the vibrations of the body 50.

[0051] In particular, the sensor 2, housed in the body 50 and more precisely in the chamber 51, is located near the outlet orifice of the nozzles 1 of the nozzle holder 5.

[0052] According to a variant, the sensor 2 is housed at the junction between the spray bar and the nozzle holder 5 in order to have only one sensor 2 for a plurality of nozzles 1.

[0053] This location as close as possible to the outlet orifice of the nozzles allows the most precise measurement possible of the vibrations of the body 50 and in particular of the noise generated by the exit of the product to be sprayed through the outlet orifice of the nozzle 1.

[0054] The greater the vibrations of the body 50 measured, the greater the noise generated by the exit of the product to be sprayed through the outlet orifice of the nozzle 1.

[0055] When the nozzle 1 is partially obstructed, the vibrations of the body 50 are significant and the noise generated is also significant.

[0056] When the nozzle 1 is completely obstructed, the vibrations of the body 50 cease, and no more noise is then generated.

[0057] The vibration sensor 2 can further be configured to transform the vibration measurement into an electrical signal, if necessary to amplify said electrical signal, and optionally to transform it into a differential signal.

[0058] Advantageously, the sensor 2 is a piezoelectric sensor.

[0059] The spraying system further comprises a calculation unit configured to compare the measurement of the vibrations of the body 50 with a reference signal to determine the obstruction state of the spray nozzle 1.

[0060] The sensor 2 configured to measure the vibrations of the body 50 makes it possible, by means of the calculation unit, to determine the obstruction state of each of the nozzles 1 when the nozzle holder 5 comprises a plurality of nozzles such as the example shown in the figures.

[0061] The vibration sensor 2 being configured to measure the vibrations of the body 50 of each of the nozzles 1 and to determine the obstruction state of each of the nozzles 1.

[0062] In particular, the vibration sensor 2 is configured to send the electrical signal, where appropriate transformed into a differential signal, to the calculation unit, itself configured to compare said transported differential signal to a predetermined threshold signal.

[0063] According to a particular embodiment of the invention, the spraying system further comprises a second sensor configured to measure the ambient noise of the spraying system. The measurement made by the vibration sensor 2 can then be compared to the measurement made by the second sensor, so as to allow a precise measurement of the vibration of the body 50 of the nozzle holder 5. In particular, the measurement of the second sensor makes it possible to detect only the ambient noise, and therefore to filter it from the measurement of the first sensor 2, so as to have only the measurement of the vibrations of the body 50. To this end, the measurement of the ambient noise is for example deduced from the measurement of the vibrations of the body 50 of each of the nozzles 1.According to one embodiment, in this case, the measurement carried out by the second sensor can be carried out even before the spraying system is started, that is to say before the product to be sprayed passes through the orifice of the nozzle 1 or nozzles 1.

[0064] The second sensor is arranged on the spraying system, in particular on the spraying boom, in particular in a location remote from the first sensor, so as to capture the surrounding noises of the spraying boom, such as the noise of the engine of the agricultural machine for example, but without capturing the noises generated by the spraying of the phytosanitary product by the spraying nozzles.

[0065] Advantageously, the second sensor is a piezoelectric sensor.

[0066] For example, the second sensor is configured to measure the signal corresponding to the noise generated by a PWM coil controlling the opening and closing of the nozzles 1 and / or to measure the signal corresponding to the noise generated by a motorization device of a multi-nozzle nozzle holder carrying a set of nozzles 1.

[0067] According to one embodiment of the invention, the spraying system comprises a noise amplification device. The vibration amplification device is configured to amplify the vibrations of the body 50 and in particular the noise generated by the output of the product to be sprayed through the outlet orifice of the nozzle 1.

[0068] The amplification device is arranged in the body 50 of the nozzle holder 5. In particular, the amplification device is located upstream of the outlet orifice of the nozzle 1.

[0069] It can, according to a variant, be arranged at the junction between the spray bar and the nozzle holder 5 in order to have only one amplifier device for a plurality of nozzles 1.

[0070] The amplification device may for example comprise propellers whose blades are configured to rotate in the product to be sprayed, so as to disturb the flow. of liquid passing through nozzle 1. Thus, the liquid passing through nozzle 1 vibrates more than if it had not been disturbed and therefore generates more noise. Sensor 2 therefore measures greater vibrations.

[0071] The amplification device may also comprise propellers of which at least a portion of the blades is helical. The blades are configured to rotate in the product to be sprayed, so as to disturb the flow of liquid passing through the nozzle 1. Thus, the liquid passing through the nozzle 1 vibrates more than if it had not been disturbed and therefore generates more noise. The sensor 2 therefore measures greater vibrations.

[0072] The amplification device may also comprise protrusions projecting from the walls of the body 50, in the direction of the product to be sprayed which passes through it. The protrusions are configured to deflect the flowing product in several directions and therefore to disturb it so as to increase the vibrations in the body 50 and thus increase the noise generated.

[0073] The amplification device may also comprise a vibrating reed corresponding to a blade configured to vibrate, a static mixer, a flexible membrane or any other means making it possible to obtain the same effect.

[0074] In particular, such amplifier devices make it possible to increase the vibrations of the body 50 when the spray nozzle 1 becomes blocked.

[0075] The invention also relates to a method for detecting the obstruction of at least one nozzle 1 of the spraying system as previously described.

[0076] With reference to [Fig. 3], the detection method comprises a step 100 consisting of passing the product to be sprayed through the outlet orifice of the nozzle 1.

[0077] In particular, the product to be sprayed is conveyed into the main conduit 4 ( [Fig.l]), then into the nozzle holder 5, through the body 50 of the nozzle holder 5, towards the spray nozzle or nozzles 1, then through the spray nozzle or nozzles 1 towards their outlet orifice, to then be sprayed through the outlet orifice towards the outside.

[0078] The method then comprises a step 200 consisting of measuring the vibrations of the body 50 of the nozzle 1 or nozzles 1, by means of the vibration sensor 2.

[0079] Then, the method comprises a step 300 consisting of transforming the measurement of the vibrations of the body 50 from step 200 into an electrical signal.

[0080] The method then comprises an optional step 400 consisting of amplifying the electrical signal generated in step 300. This step is implemented in a preferred embodiment of the method according to the invention.

[0081] In the particular embodiment according to which the spraying system comprises a second sensor for measuring the surrounding noise, the detection method may comprise a step 101, during which the second sensor measures the surrounding noise. In particular, step 101 may be implemented prior to step 100, i.e. even before the spraying system is started, in other words before the product to be sprayed passes through the orifice of the nozzle 1 or nozzles 1. Alternatively, the measurement by the vibration sensor 2 and the measurement of the ambient noise by the second sensor can, for example, be carried out at the same time. The measurement of the ambient noise is used to filter the ambient noise from the measurement carried out by the vibration sensor 2. In this case, the second sensor is preferably arranged at a point in the spraying system, in particular on the spray bar, remote from the vibration sensor 2.

[0082] An optional step 500 consists of transforming said amplified electrical signal into a differential signal, by means of the electronic card 3 integrated into the vibration sensor 2. The transformation of the electrical signal into a differential signal makes it possible to improve the efficiency of the method. This step is however optional.

[0083] A step 600 consists of transporting the electrical signal, if necessary transformed into a differential signal, to the calculation unit of the spraying system.

[0084] A step 700 consists of comparing said electrical signal, where appropriate transformed into a differential signal, transported to a reference signal.

[0085] According to a first embodiment, the reference signal is a predetermined threshold value pre-recorded in said calculation unit.

[0086] In this embodiment, the noise measured by the sensor 2 is compared to a predetermined threshold value. When the measured noise is greater than the predetermined threshold value, then the nozzle 1 is partially obstructed. When the measured noise tends towards zero, the nozzle 1 is completely obstructed.

[0087] According to a second embodiment, the reference signal corresponds to a calibrated threshold signal at the start of the spray nozzle 1.

[0088] In this embodiment, the noise measured by the sensor 2 is compared to a calibrated threshold signal. When the measured noise is greater than the calibrated threshold signal, then the nozzle 1 is partially obstructed. When the measured noise tends towards zero, the nozzle 1 is completely obstructed.

[0089] According to a third embodiment, the reference signal corresponds to an average of the electrical signals, where appropriate transformed into differential signals, transported from the other spray nozzles 1.

[0090] In this embodiment, the noise measured by the sensor 2 is compared to an average of the noise generated by the other nozzles 1 of the spray bar. When the measured noise is higher than the average of the other nozzles, then the nozzle 1 is partially obstructed. When the measured noise tends towards zero, the nozzle 1 is completely obstructed.

[0091] More generally, the reference signal, pre-recorded or not in the system, may depend on spraying parameters, including the speed of movement of the system. spraying, the flow rate of sprayed product, or the pressure of the product to be sprayed circulating in the spray bar of the spraying system. Thus, the calculation unit can be configured to automatically adjust the reference signal taken into account, so as to adapt it to the spraying parameters or to one of the spraying parameters. For example, if the speed or the flow rate of sprayed product or the pressure of the product to be sprayed circulating in the spray bar of the spraying system changes, then the reference signal changes accordingly.

[0092] According to the invention, the detection of the obstruction of a nozzle 1 makes it possible to generate a signal intended for the user in order to warn him of the potential blockage of one or more spray nozzles. Indeed, the suspicion of the blockage of at least one nozzle 1 can take the form of an audible or luminous signal for example.

[0093] It will also be noted that the invention is not limited to the embodiments described above. It will indeed appear to those skilled in the art that various modifications can be made to the embodiment described above, in light of the teaching which has just been disclosed to them.

[0094] In the detailed presentation of the invention which is made above, the terms used must not be interpreted as limiting the invention to the embodiment set out in the present description, but must be interpreted to include all equivalents whose prediction is within the reach of a person skilled in the art by applying his general knowledge to the implementation of the teaching which has just been disclosed to him.

Claims

Claims

1. Spraying system for an agricultural sprayer, comprising a spray boom having a main duct (4) and at least one nozzle holder (5) connected to the main duct (4), the nozzle holder (5) comprising: • a body (50) housing an inlet duct for the product to be sprayed configured to be supplied with product to be sprayed by said main duct (4); • at least one first nozzle (1) for spraying said product comprising at least one outlet orifice for said product and configured to be supplied with product by the product inlet duct and to convey said product to said outlet orifice; • at least one vibration sensor (2) and housed in said body (50) or connected to said nozzle (1); said spray boom being configured to spray product by said first spray nozzle (1);said vibration sensor (2) being configured to measure the vibrations of the body (50), said spraying system further comprising a calculation unit configured to compare the measurement of the vibrations of the body (50) or of the nozzle (1) with a reference signal to determine the state of obstruction of said nozzle (1).;

2. A spraying system according to claim 1, wherein the vibration sensor (2) is a piezoelectric sensor.

3. Spraying system according to one of claims 1 to 2, in which the vibration sensor (2) is housed in the body (50) of the nozzle holder (5), near the outlet orifice of said nozzle (1).

4. A spraying system according to any one of claims 1 to 3, wherein the vibration sensor (2) is further configured to transform the vibration measurement into an electrical signal.

5. A spraying system according to claim 4, wherein the vibration sensor (2) is further configured to transform the electrical signal into a differential signal.

6. A spraying system according to claim 5, wherein said vibration sensor (2) is configured to send the differential signal to the computing unit which is configured to compare said differential signal to a predetermined threshold signal.

7. A spraying system according to any one of claims 1 to 6, wherein the nozzle holder (5) comprises a plurality of spray nozzles (1), the vibration sensor (2) being configured to measure the vibrations of the body (50) of each of the nozzles (1) and to determine the clogging state of each of the nozzles (1).

8. A spraying system according to any one of claims 1 to 6, wherein the nozzle holder (5) comprises a plurality of spray nozzles (1), a vibration sensor (2) being connected to each of the nozzles (1) and being configured to measure the vibrations of each of the nozzles and determine their clogging status.

9. A spraying system according to any one of claims 1 to 8, comprising a vibration amplification device located upstream of the outlet orifice of the spray nozzle (1), said amplification device being configured to amplify the vibrations of the body (50) or of the nozzle (1).

10. A spraying system according to claim 9, wherein the amplification device comprises propellers comprising blades configured to rotate in the product to be sprayed, so as to disturb the flow of product to be sprayed passing through the nozzle (1).

11. Spraying system according to claim 9, in which the amplification device comprises protrusions projecting from the walls of the body (50), in the direction of the product to be sprayed which passes through it and configured to disturb said product.

12. Spraying system according to one of claims 1 to 11, further comprising a second sensor configured to measure the surrounding noise of the spraying system, so that the measurement made by the vibration sensor (2) can be compared to the measurement made by said second sensor.

13. Method for detecting the obstruction of at least one nozzle (1) of a spraying system according to one of claims 1 to 12, comprising at least the following steps: • a step (100) consisting of passing the product to be sprayed through an orifice of said nozzle (1); • a step (200) consisting of measuring the vibrations of the body (50) of the nozzle (1) by means of a vibration sensor (2); • a step (300) consisting of transforming the measurement of the vibrations into an electrical signal; • an optional step (500) consisting of transforming said amplified electrical signal into a differential signal, by means of a card (3) integrated into said vibration sensor (2); • a step (600) consisting of transporting said electrical signal, where appropriate transformed into a differential signal, to a calculation unit of the spraying system; • a step (700) consisting of comparing said electrical signal, where appropriate transformed into a differential signal, transported to a reference signal.

14. Detection method according to claim 13, comprising a step (101) of measuring the surrounding noise, in particular prior to the step (100) of passing the product to be sprayed through an orifice of said nozzle (1), the measurement of the surrounding noise being filtered from the measurement of the vibrations of the body (50) of the nozzle (1).

15. A detection method according to claim 13 or 14, wherein a step (400) of amplifying the electrical signal is interposed between said step (300) of transforming the vibration measurement into an electrical signal and said step (500) of transforming said amplified electrical signal into a differential signal, by means of a card (3) integrated into said vibration sensor (2).

16. Detection method according to one of claims 13 to 15, in which the reference signal is a predetermined threshold value pre-recorded in said calculation unit.

17. Detection method according to one of claims 13 to 15, in which the reference signal corresponds to a threshold signal calibrated at the start of said at least one spray nozzle (1).

18. Detection method according to claim one of claims 13 to 15, in which the spray bar comprises a plurality of spray nozzles (1) and in which the reference signal corresponds to an average of the electrical signals, where appropriate transformed into differential signals, transported from the other spray nozzles (1).

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