ES2779034T3 - Device and / or conduit for detecting fuel supplied to an internal combustion engine - Google Patents

Abstract

Arrangement of a device for detecting at least one parameter of a fuel or mixtures thereof supplied to an internal combustion engine, comprising sensor means (1, 1 ') to be in contact at least partially with the fuel or mixtures thereof, the sensor means (1, 1 ') being externally associated with a conduit (2) of the type "fuel conduit", "common conduit" and the like, to supply the fuel or mixtures thereof to the engine, the means being sensors (1, 1 ') housed in a seat of a body or fitting comprising a coupling or tubular outlet element (80) downstream associated or connected to an inlet (3b) of the fuel conduit (2), and why The arrangement comprises fixing or support means (86, 86 ', 86' ', 86' '', 86IV, 86V, 86VI 88, 89) to mechanically fix and / or support the sensor means (1, 1 ') or its housing seat (50, 60, 90, 90 ') or the fitting (52, 52' 62, 62 ', 62' ', 62' '', 62IV, 62 V, 62VI, 92, 92 ') over the fuel conduit (2), substantially adjacent to the fuel conduit in connection with at least two distinct or separate points, one in a substantially intermediate or terminal position of the conduit, and another in at least one point substantially located in a terminal or opposite or intermediate position of the fuel conduit, so that the conduit (2) and the sensor (1) will behave substantially as a rigid part.

Description

DESCRIPTION

Device and / or conduit for detecting fuel supplied to an internal combustion engine

The present invention refers, in general, to a device for detecting characteristics of a liquid, such as the type of at least one liquid and / or the percentage of mixing of different fluids and / or the presence and / or concentration of some elements in a fluid, such as a liquid fuel supplied to internal combustion engines, for example, gasoline, diesel, ethanol, and so on. Preferably, the present invention relates to a detection device equipped with suitable means, in particular of the hydraulic and / or mechanical type, for its connection or mounting in a conduit for a ustible or combustible liquid, in particular a conduit associated or associable with valves or injectors of internal combustion engines, such as the so-called "fuel rail". In general, the connection or mounting means allow removal of the device, for example, for maintenance or replacement of the device or the associated conduit.

In current internal combustion engines, which run on either gasoline or diesel or other fuels, there is a growing need to check the characteristics of the fuel supplied to the engine, so that the car's control system can make the necessary changes. in engine operation.

This is done by modifying the injection parameters of the fuel mixture, when these are controlled electronically (eg according to so-called "engine mapping").

Another need that is strongly perceived is the detection of the quality of the fuel, which can have such a concentration of impurities or other compounds, especially water, that it can cause problems in the operation of the engine, or it can contain mixtures of different fuels. .

This is particularly important in so-called flex engines, that is, engines capable of running on different types of fuel, such as ethanol and gasoline, gas and gasoline, and so on. Various types of sensors are known in the art, the operation of which is based on the detection of different physical parameters, for example, optical, electrical, magnetic or the like.

One of the important aspects related to the sensors considered here is their position on the engine; in fact, it is not always possible to find the necessary space, and this affects the type of measurement that will be carried out.

For example, if the sensor is arranged near the tank of a motor vehicle, the difference in density between the different fuels, or between the latter and any amount of water that they may contain, can cause false readings due to stratification of liquids that have a different density.

In practice, in such situations the sensor will detect the concentration of the liquid layer in which it is immersed, although without taking into account any other liquid that constitutes different layers (upper or lower).

For this and other reasons, it is preferable to arrange the sensors in the fuel circuit of the combustion engine, that is, downstream of the tank; Some examples of possible sensor arrangements are described in German patent application DE 103 09720, where the sensor is incorporated in the injector of a diesel engine, or along a fuel passage, as disclosed by For example, in US Patent No. 6,885,199.

These solutions are intended for injection engines, both the normal ones (that work on diesel or gasoline) and the aforementioned flexible ones, which comprise one injector per cylinder.

It can be easily understood that the solution in which the sensor is associated with an injector may be difficult to implement in multi-cylinder engines, for example, with four or more cylinders, or with a plurality of sensors.

In fact, in such a case, each sensor will provide indications about the fuel being injected into the respective cylinder, and therefore the engine control system (typically an electronic control unit) will have to process readings that they may be different from each other.

If, on the one hand, this allows, in principle, to achieve a precise adjustment of the injection, on the other hand, it can make the injection management process more complex; therefore, in some applications, such as low cost motor vehicles, it may not be economically feasible to use one sensor per cylinder.

Furthermore, the sensor incorporated in the injector must necessarily be small, and this can make such a sensor difficult and expensive to manufacture.

Finally, installing the sensor near the engine can cause major reading errors, since the The sensor can be overheated, for example, by a fuel heater such as that described in EP2108809 and WO2011055295 of the present applicant.

Therefore, solutions such as that described in the aforementioned US patent (US 6,885,199), in which a sensor is mounted along a conduit, can be rendered ineffective by the presence of such a heater.

It is worth mentioning that sensors with different configurations also have different transfer functions, and therefore, dedicated systems (instruments, software, etc.) are required for their control, depending on each case, resulting in higher costs.

In this context, trade-offs are available where the sensor is inserted into the rail supplying fuel to the injectors or cylinders, referred to as the “fuel rail” for gasoline engines or "common rail" for diesel engines.

However, this can be a limiting factor, not only because proximity to fuel heaters can affect sensor performance, but also because, if a sensor is placed in the "fuel rail" or "fuel rail" common ”, it will be difficult to find enough space to also add a heater.

The present invention seeks to overcome the aforementioned drawbacks of prior art sensors.

In other words, the technical problem underlying the invention is to provide a device for detecting the characteristics of a liquid, in particular, but not limited to, a fuel or mixtures thereof for internal combustion engines, which allows a reliable detection in a simple manner, that is, substantially without modifying the manner in which fuel is supplied to the engine.

Another problem is to provide a device to detect the characteristics of a liquid, in particular, without limitation, a fuel or mixtures thereof for internal combustion engines, which can be included in systems equipped with fuel heaters, in particular heaters associated with the fuel line.

The idea to solve the aforementioned problem is to detect the characteristics of the fuel that flows in the "fuel line" or "common line" at a point external to it, preferably in the vicinity of said "fuel line" or "common line. ”.

Preferably, at that point the fuel is at substantially the same pressure level as the "fuel rail" or "common rail", which can range from a few bars for flexible engines (eg 1.5-3.50 bars) to many hundreds of bars for diesel engines.

The detection of the characteristics of the fuel flowing in the fuel rail is independent of the number of cylinders: in practice, the sensor being used does not have to be changed for each application that has a different number of cylinders.

Furthermore, the fuel within the conduit has stable and uniform pressure characteristics, thereby ensuring accurate and reliable detections.

The pressure variations in the liquid can be due to a lower level of fuel in the tank or to the opening of the engine valves: a pressure higher than atmospheric makes the variations less relevant in percentage terms.

The aforementioned technical problem is solved with a detection device having the characteristics set out in the attached claims.

The invention also relates to a fuel line that can be associated with a sensor according to the invention or a fuel line of the "fuel line" or "common line" type, which has the characteristics set out in the appended claims.

Said characteristics, their effects and the advantages of the present invention will become more apparent from the following description of a few examples of an embodiment thereof as shown in the attached drawings, which are provided by way of explanatory and non-limiting example, where:

Figure 1 is a perspective view of an embodiment of a sensor that can be used in the device according to the invention;

Figures 2 and 3 are exploded perspective views, from two respective points of view, of the sensor of Figure 1;

Figure 4 is a perspective view of a first example of a device not according to the invention, applied to one end of a fuel supply conduit;

figure 5 is a partially sectional view of the device of figure 4;

Figure 6 is an exploded view of the device and conduit of Figure 4;

Figures 7 and 8 show a perspective view and an exploded view of the device according to the invention; Figures 9 and 10 show a perspective view and a partially sectional view of a variant of the device according to the invention;

Figure 11 is an exploded view of the device of Figure 9 and the associated fuel conduit in which the first has been applied;

the groups of figures 12, 13, 14 and 15, 16, 17 illustrate other respective variants of the device according to the present invention;

Figures 18, 19 and 20 show three other respective embodiments of the device according to the invention; Figures 21, 22 are a perspective view and an exploded view of a connection fitting not forming part of the invention;

Figure 23 is an exploded view of another fitting that does not form part of the invention;

Figure 24 illustrates in detail a component of the device according to the invention, such as a sensor as described herein, in an idle condition;

Figure 25 illustrates the piezoelectric bending element component of Figure 24 energized by an electrical potential difference;

Figure 26 illustrates a circuit capable of measuring the characteristics of a liquid in which the component or sensor of Figures 24 and 25 is immersed.

figure 27 shows an acoustic variant of the sensor of figure 1;

figure 28 shows an optical variant of the sensor of figure 1;

figure 29 shows an electrical variant of the sensor of figure 1;

Figures 30, 30a; 31, 31a show other respective variants of the sensor of figure 1.

With reference to the above-listed drawings, particularly Figures 7 to 20, a device according to the invention is designated collectively as D and comprises one or more sensors 1, which are also referred to as sensor means, said device being embedded sensor, at least partially, in an operating condition, by a fluid flowing in a fuel supply conduit 2 corresponding to an internal combustion engine.

The conduit 2 is of the "fuel conduit" type, that is, a conduit comprising a fuel inlet 3a, which, in the example of Figures 4, 5, is located at one end 2a, and a plurality of outlets 4, which lead to the injectors (not shown in the drawings) of an internal combustion engine of the flexible type that runs on different fuels, such as gasoline and ethanol, or the like.

As can be seen in the drawings, the dry part of the sensor 1 comprises a housing 5 for the circuit components, which is closed by a cover 6; the external part of the sensor is also connected to the electrical power supply and to the engine management network of the motorized vehicle in which the device is installed, by means of a three-pole electrical connector 7.

The housing 5 of the sensor 1 is shaped such that it contains at least one detection and / or control circuit, such as an electronic board 9, which carries out at least the function of processing the signals obtained or transmitted from the element. sensor 14 through terminals 12, 13 to which it is connected, and then sending the detected data in the form of electrical signals to one or more of the terminals 11 of connector 7; in this example, said electrical signals are generated by deformation of a so-called piezoelectric bending element 14 (see Figures 26 and 27).

Said housing 5 associated with sensor 1 is preferably adapted to also contain an insulating element 10, in particular a suitable material to surround or at least partially cover said electronic board 9, such as a polymer or a resin, for example, poured in the housing and / or on the circuit or board 9 and then cured or hardened; said insulating element is adapted, in particular, to protect said circuit or board 9 against external agents or contaminants.

As also shown in Figures 26 and 27, the sensor comprises an element 14 adapted to vibrate when properly energized, such as a sheet associated with a piezoelectric layer (also called a "bending element" (from English, "bender ”)), Which is made to vibrate by means of electrical signals at preset frequencies, in order to be able to detect properties of the fuel, such as viscosity, density or the like, for example, by detecting variations in vibration induced by the fluid or fuel with which the sheet or bending element comes into contact.

For detection, the piezoelectric bending element 14 must be immersed in and / or immersed by the liquid fuel and must be energized by means of an alternating voltage that causes it to vibrate at a certain resonance frequency. Figure 28 shows an example of a circuit and / or plate 9 associated with the bending element 14, in particular adapted to control the resonant frequency of the latter.

The piezoelectric bending element 14 comprises one or more piezoelectric layers polarized in thickness 14a and 14b, separated by a dielectric, constrained together and integrated at one end with the casing 5 through holes 111 compatible with fixing means (not shown in drawings) included in said casing 5; this assembly, when supplied electrically, produces a bending deformation.

Terminals 12 and 13 are associated, respectively, to the two opposite surfaces of piezoelectric bending element 14, by soldering or the like.

The inner (wet) part of the sensor also comprises, in addition to the piezoelectric bending element 14, which is inserted and held in position by means of an opening 15 in front of the housing 5, a notch 16a around the opening 15 The notch houses a sealing gasket 16, which prevents leakage of the liquid present in the conduit 2, for example, gasoline or ethanol.

The sensor comprises two terminals 12 and 13, consisting of filiform conductors obtained by means of cylindrical bars made of copper or other suitable electrically conductive material, and having free curved ends 12b, 13b; In the operating condition of the sensor, these curved ends 12b, 13b are directly in contact with the piezoelectric bending element 14.

The base ends 12a, 13a of the internal terminals 12, 13 plug into suitable seats 21 of the plate 9.

The seats 21 are also used as clamps to provide electrical contact between the terminals 12, 13 and the circuit associated with the plate 9; therefore, in order to ensure correct contact, at the base ends 12a, 13a there are, in this example, insulating rings 19 and anti-extraction rings 20.

A few models of piezoelectric bender elements are commercially available that can be applied to the present invention (for example, those manufactured by the American company Sinoceramics).

The piezoelectric layers 14a, 14b of the bending element 14 are connected to the control circuit 9 by means of the terminals 12 and 13.

The output voltage of the bending element 14, or its resonance frequency, is monitored in order to detect changes in the viscosity of the fluid.

The viscosity of the fluid can be determined as a function of the damping of the vibrations of the bending element, or the variation of the vibration frequency of the bending element, or, more generally, of the frequency response of the bending element.

Referring to the diagram shown in figure 26, it is shown that it is possible to apply a voltage to the bending element through the terminals 12 and 13, with an amplitude and a frequency optimized to make it vibrate.

In this way, the structure of the bending element is subjected to bending cycles as a function of the supply voltage, which will preferably be that of fundamental resonance. Said structure and / or frequency can be optimized according to the type of fluid to be measured.

The diagram of figure 26 shows an electronic arrangement comprising a drive stage 103 of the bending element 14 and a detection stage 101, 102, 103 of the bending element 14, which may also together constitute a feedback loop 100 to properly cause the bending element to oscillate at its resonance frequency; said detection stage and / or feedback loop 100 comprises an alternating voltage meter 101, an analog / digital converter 102 and a microcontroller 103. The alternating voltage meter 101 is used to monitor the output signal of the bending element and output to a data that will be proportional to the frequency and the amplitude of the voltage detected.

This continuous data stream is then sent to the microcontroller 103, which can process it using suitable calculation algorithms and / or on the basis of predefined data tables, and / or can transform it, for example by linearizing it.

In order to be able to drive the bender element to its natural resonant frequency in a given environment, the phase of the feedback signal can preferably be advanced (or retarded) by approximately 90 °.

This function is carried out by the microprocessor 103 based on the reading taken by the alternating voltage meter 101.

The microcontroller closes the feedback loop 100 by suitably controlling the energizing signal from the bending element such that optimum resonance is maintained, and, based on the received measurements, can determine the viscosity of the fluid.

The resonant frequency depends on the physical dimensions of the bending element and the material with which it is made: for specific automotive applications, it will probably be necessary to operate at frequencies higher than the typical ones generated by the vehicle: therefore, it can be to recommend, in particular, the manufacture, by using MEMS techniques, of a miniaturized bending element operating at high frequencies. A MEMS bending element can be made of silicon or alumina, and conductive and piezoelectric elements can be made by screen printing or using typical microelectronic techniques, such as thermal evaporation, sputtering and CVD for the active layers.

As an alternative, it is possible to achieve the same function using a piezoelectric element associated with a piezoresistive element, where the piezoelectric element is used to force the vibration, and said piezoresistive element is used as a sensor element to measure the amplitude and phase of the vibration. .

Said piezoresistive element can be of the type by screen printing or by position; for example, it can be done by depositing piezoresistive ink on a suitable insulating or insulating substrate or support.

It is important to note that the installation of the bending element considerably affects its viscosity reading sensitivity, which can be significantly increased by creating suitable constraints in the form of fixed walls located at a suitable distance from the vibrating element. In fact, the propagation of the probes generated by the shear stress, which, in turn, depends on the viscosity of the medium, is extremely limited: therefore, the variation of the damping of the bending element can only be measured if the element The bender is suitably housed within a receptacle designed to maintain a small distance between the stationary and vibrating parts. Through the use of MEMS technologies, it is possible to manufacture both the vibration elements and the fixed elements in a single piece, with micrometric tolerances and at a low cost.

The output voltage or resonant frequency is monitored in order to determine changes in viscosity.

The electrical signal obtained by applying an alternating potential difference to the terminals 12, 13, and, therefore, to the piezoelectric bending element 14 or to any other sensor elements, makes it possible to obtain an indication of the characteristics of the liquid fuel in the conduit. two.

For example, the presence of additives in varying percentages in gasoline (for example, antiknock additives, solvents, etc.) or of water in ethanol, will produce changes in the physical properties of the liquid, such as viscosity, density, speed , etc.

As will be explained in more detail hereinafter, the properties of the liquid that can be detected through the present invention may differ, however, depending on the type of sensor being used, which need not necessarily be , a piezoelectric bending element; therefore, the detections carried out can be electrical (inductive, resistive, capacitive, etc.), acoustic, optical or even combinations of one or more of these variants, or any other suitable sensor for this purpose.

The sensor can detect said changes in the physical properties of the liquid, preferably as a function of a variation in the voltage and / or electric current that circulates in the circuit associated with the plate 9, which, when properly processed, it can provide an indication of the composition and / or other characteristics of the fuel.

The main embodiment of the device D according to the invention comprises a fitting or body 52 of the sensor 1 described so far.

The use of conduit 52 also allows the sensor 1 to be advantageously moved further away from the engine (not shown in the drawings) or any other heat source, in order to improve the stability of the readings. To this end, also in the event that heat is propagated to the sensor under conditions of static fuel flow, some parts of the sensor 1 and / or device D can be advantageously adapted to dissipate heat, that is, they can be realized with a thermally conductive material, such as a suitable metallic or polymeric or thermoplastic material, for example, loaded with thermally conductive particles, etcetera; said parts of the sensor 1 can be, for example, the housing 5 and / or the body or fitting 52 and / or hydraulic connection means fixed to the fuel pipe 2 and / or mechanical fixing and / or support means fixed to the pipe Fuel 2, as will be described further below.

With reference to the group of Figures 4 to 6, the device shown therein, which does not form part of the invention, comprises the body or hydraulic fitting 52 that has a plurality of openings or seats or pathways, where an inlet 53 is connected to a fuel supply conduit or to the distribution side of a fuel supply pump (not shown in the drawings) by means of a coupling 54; fitting 52 also comprises a seat 50 having an aperture housing sensor 1, and an outlet 52b that communicates downstream with a fuel conduit 2 of the fuel conduit type.

Inlet coupling 54 may be integrated with connecting port 52, eg, co-molded or molded with the plastic fitting.

In this way, the fuel, which, in flexible combustion engines, is at a pressure greater than 2.5 bar, or several hundred bars in diesel engines, flows into the fitting 52 and, after having passed through it , enters conduit 2; said fuel flow comes into contact with or embeds sensor 1 and / or said sensor element or bending element 14, preferably axially with respect to sensor 1 or substantially parallel to said sensor element 14.

To fix the sensor 1 to the fuel conduit 2, the fitting 52 has a male thread 56 adapted to be coupled to a threaded ring nut 57 associated or associable to the conduit or "fuel conduit" 2, and rotatably constrained with an end or head of an axially hollow adapter insert 58 (also referred to as attachment or support means), the opposite end or threaded stem of which is engaged or interconnected with a corresponding thread at the end of conduit 2 (visible in Figures 5 and 6).

Like the inlet fitting 54, the insert 56 can also be integrated with the fitting 52, for example it can be co-molded or molded with the plastic fitting.

Furthermore, in the fitting 52 a slot 52a is also provided in a notch 17 of the housing 5 of the sensor 1, so that the latter is fixed to the fitting 52 by means of the teeth of the clip 8 which engages one of the slots 17, 52a; in this way, said fixing means 8 make it possible to fix and / or integrate said body 52 and said casing 5 with each other.

Sensor 1 and / or body 52 can therefore be firmly mounted outside of the fuel line or "fuel line" 2, even in the presence of high pressures in the fuel line, such as those required by injection engines. or diesel.

In practice, this solution makes it possible to mount the device of the invention in existing tubes or conduits without having to make any changes to them.

The hydraulic tightness of the system is guaranteed by means of a set of gaskets 59a, 59b, 59c adapted to prevent leaks of the pressurized fuel. Also, between the fitting 52 and the sensor 1 there is an O-ring 15a, similar to the seals located between the fitting 52 and the coupling 54, and / or interposed between the fittings 52 and 58, and / or interposed between the fuel conduit 2 and fitting 58.

To facilitate the installation of the gasket 15a, the sensor 1 comprises a seat 15b capable of firmly receiving the gasket 15a; said seat 15b is located near notch 17.

When device D is in operation, a flow of fuel enters through inlet 53 of connection fitting 52 and runs through seat 50, thus embedding bending element 14 in a direction predominantly parallel to the axis of the latter. Finally, said fuel flow reaches conduit 2, passing through outlet 52b and dividing between outlets 4 before entering the engine (not shown in the drawings).

Figures 4, 5, 6 represent solutions suitable for application to one end of the fuel line 2 of the "fuel line" or "common line" type.

However, this is not always possible because, for example, the available space could be insufficient: in fact, it must be taken into account that these fuel lines are located in the vicinity of the cylinder head, where, usually, injectors and other components are also present, and therefore it is not certain that there is sufficient space to apply the device of the invention at the end of the conduit 2 or that said application will be advantageous.

In such circumstances, the device of the invention can be arranged in a radial position or adjacent to an intermediate or terminal region of the fuel conduit 2.

Under these conditions, the sensor must be firmly supported to be able to withstand high stresses resulting, for example, from vibrations transmitted by the engine and / or produced by the vehicle, or arising from the pressures involved in the fuel supply system. , as mentioned above.

Preferably, the sensor should be supported without the need for changes to the environment in which the fuel line is arranged, i.e. the engine compartment, or to the engine components housed in the compartment thereof.

To meet these requirements, according to this variant of the invention, the sensor is supported in connection with at least two points of the fuel line, in order to obtain conditions of stability and rigidity sufficient to withstand the stresses derived from the high pressure of the fluid flowing in it, as well as the aforementioned vibrations and / or shocks of the vehicle

In other words, under these conditions the duct 2 acts directly as a support element for the sensor 1 to which it is coupled, particularly in at least two different and / or separate points, preferably in substantially opposite positions or with at least a point located substantially in a terminal position, possibly with at least one point located in a substantially intermediate position, with respect to the sensor and / or the hydraulic fitting 62 thereof, such that the conduit 2 and the sensor 1 behave substantially like a rigid piece.

In particular, according to the invention, advantage is taken of the hydraulic connection between the sensor 1 and the duct 2, which will thus have two functions, that is, the hydraulic function and the function of supporting the sensor and / or the associated fitting.

In this way it is possible to maintain a sufficient distance between said fixing points of the sensor 1, and / or the hydraulic connection 62 associated with it, and the fuel line 2, since the hydraulic connection can be configured in the most appropriate way to the desired purpose, as will be explained in detail later.

The sensor 1 and / or the three-way fitting associated with it is supported in connection with two different points of the fuel duct 2, mechanically at one point and mechanically-hydraulically at the other point, since, as mentioned above, The invention takes advantage of the hydraulic connection between sensor 1 and / or the associated three-way fitting.

Figures 7 and 8 represent a possible embodiment of the invention that incorporates these situations.

In this embodiment, the sensor 1 is housed in a seat 60 of a body or fitting 62, analogous or similar to the body 52, 52 'of the previously described embodiments, although said fitting 62 may have a slightly greater length and / or a different way.

For this reason, in the fitting 62 there is also a groove 62a which corresponds to the notch 17 of the sensor 1, so that the latter can be fixed to the fitting 62 by means of the teeth of the clip 8 as already described.

In order to guarantee hydraulic tightness, between the fitting 62 and the sensor 1 there is, also in this variant, a seal 15a.

An inlet 63 of fitting 62 is connected upstream to the distribution side of the fuel supply system and / or associated pump (not shown in the drawings) through an inlet tubular element or coupling 64; the fitting 62 is connected downstream to a coupling or tubular outlet element 80 associated with or connected to an inlet 3b of the fuel conduit 2.

In this embodiment, the coupling 80 is attached to the inlet 3b and the fitting 62. More specifically, the coupling 80 and the inlet 3b of conduit 2 are connected to each other by means of threaded couplings. respective, such as a male threaded insert 83 surmounted by a nut 84 integral with said coupling 80; furthermore, said threaded insert 83 is positioned at one end of said coupling 80, and nut 84 is coaxial with said threaded insert 83, to facilitate connection of said coupling 80 to inlet 3b, which is equipped with a respective female threaded coupling . Regarding the connection between the coupling 62 and the coupling 80, it is implemented through hydraulic connection means comprising quick couplings 70, 80; coupling 70 comprises a circular structure 72 comprising a push button 73 and integrating elastic elements, said structure interconnecting with an annular element 85 included in coupling 80. In addition, coupling 70 also comprises a set of gaskets 71 that guarantee a proper seal between fitting 62 and coupling 80 when fuel is flowing into it. The seal assembly 71 comprises two rubber O-rings 71a, between which there is a metallic O-ring 71b, the O-rings being positioned around a centering ring 71c; said centering ring comprises a central projection 71d that allows its correct positioning, preventing said ring 71c from sliding inside the fitting 62. Around that part of the ring 71c that protrudes outside the fitting 62, the coupling 70 is positioned; said positioning is simplified by the presence of a housing seat 68 at the outlet of the fitting 62, compatible with the coupling 70. This seat 68 allows the push button 73 to be pressed also when the coupling 70 is in an operating condition. During assembly, this seat 68 can be elastically deformed in order to facilitate the positioning of the coupling 70 around the centering ring 71c.

The fitting 62 is held in position by means of a clamp 86; said clamp 86 is formed by two L-shaped parts 86a, 86b, each of which comprises, respectively, a horizontal part 86d, 86e; said horizontal portions 86d, 86e are slidably coupled to a base guide 87 (also referred to as fixing or support means) associated with the fuel conduit 2. The guide 87 comprises two opposite guides 87d, 87e compatible, respectively, with horizontal parts 86d, 86e to provide a quick connection; said guides 87d, 87e have a linear shape and are obtained in respective compatible reliefs 87a and 87b included in the guide 87. This solution makes it possible to adjust the position of the fitting 62 with respect to the duct 2, preferably in a direction parallel to the axis of the duct 2 .

As can be easily understood, in this variant of the invention the sensor 1 is supported, together with the fitting 62, at two points of the fuel duct 2, that is, by the inlet 3b through the coupling 80 and by the reliefs 87 by means of clamp 86.

In this way, the same assembly conditions of the sensor 1 with respect to the fuel flow can be achieved as those of the previous examples, while guaranteeing, at the same time, the necessary stability of the sensor 1 to withstand the large stresses transmitted by the engine and / or produced by the vehicle, as well as those caused by the pressure of the fuel that is supplied to the engine.

Advantageously, this result is achieved by taking advantage of the hydraulic connection between the sensor 1 and the associated fitting 62, thanks to the coupling tube 80 which, in addition to the normal hydraulic function, also has the mechanical function, together with the clamp 86, of support. connector 62 with sensor 1.

In this context, it should be noted that the 90-degree shape of the coupling tube 80 represents an advantageous and effective feature, since its vertical part constitutes de facto an upright that supports the horizontal part of the coupling 80, which is connected at one end to the fitting 62.

The latter is supported at the other end by the clamp 86, thus being rigidly fixed to the fuel duct 2 to withstand the stresses induced by the aforementioned vibrations of the engine or vehicle.

Similar considerations apply to the variant illustrated in Figures 9 and 11, wherein the duct 2 comprises an inlet 3b 'positioned at one end of the duct 2 and radially with respect to the latter.

In this variant, the sensor 1 is inserted into a fitting 62 'that has the same function as the fitting 62 of the previous embodiment; said fitting is kept integral with conduit 2 by means of a clamp 86 'having an S-type shape, to limit the space occupied inside the compartment of an engine (not shown in the drawings).

The clamp 86 'comprises a fixing eye 88 at its lower end, while, at the opposite end, it is coupled to the fitting 62' by welding, gluing, or the like; said fixing eye 88 is compatible with a fixing hole 89 comprised in duct 2, so that duct 2 and clamp 86 'can be made to form a single piece with each other by means of a bolt or fixing means similar (not shown in the drawings), thus fixed, the fitting 62 'to the conduit 2, possibly only by changing the length of said bolt.

Such a solution makes it possible to use a bolt or similar fixing means, typically already used to fix the conduit 2, also to fix the clamp 86 'of the fitting 62 and / or the sensor 1.

Preferably, the clamp 86 'also comprises a positioning and / or anti-rotation element 141, located in the vicinity of said fixing eye 88, which is coupled to a respective seat 142 located near the fixing hole 89 of conduit 2. Said positioning and / or anti-rotation element 141 and said seat 142 are substantially complementary to each other, that is, they correspond precisely; in particular, this is useful for centering the eyelet hole 88 with the fixing hole 89, thus making said bolt easy to install, and / or to avoid any angular movement of the fitting 62 with respect to the fuel duct 2 , which guarantees more solidity and a more secure retention of the parts, and also avoids any anomalous tension on the fuel coupling.

As mentioned, this variant also uses a coupling 80 with suitable sealing means. However, in this case, the coupling 80 is positioned in a manner opposite to the previously described variant, that is, it is made to be integral with the fitting 62 ', thus requiring a female thread 65 at the outlet of the fitting 62 ', which will engage a respective male thread of the fitting 80.

The other end of the coupling 80 creates a quick connection by means of the annular mounting element 85, which connects to a quick coupling 81 provided at the inlet 3b 'of conduit 2.

Inside the conduit 3b ', the quick coupling 81 comprises two rubber O-rings 81a, a metal O-ring 81b between the two rubber O-rings 81a, and a centering ring 81c; the O-rings 81a, 81b are positioned below the centering ring 81c, while, on the top of the latter, a support ring 81d is mounted, compatible with the edge of the inlet 3b '. That part of the quick coupling 81 that is external to the conduit 3b 'comprises a reducer of diameter 81e compatible with the support ring 81d, a spacer 81 f that fits into the reducer of diameter 81e, and a hollow cylindrical support 81g compatible in the part bottom with spacer 81f and, on top, with a click-fit connector 81h compatible with coupling 80.

The click-fit connector 81h comprises a push button 81 i which, when depressed, elastically modifies a constriction mechanism (not shown in the drawings) located within the click-fit connector 81h; said restraint mechanism engages annular element 85, thus allowing quick coupling 81 to constrict with coupling 80.

This solution allows the assembly of sensor 1 - fitting 62 'to be mounted with a substantially vertical movement, until the quick coupling 81 reaches its retention position, plus a slight lateral movement to achieve that said positioning and / or anti-rotation element 141 engages respective seat 142 and eyelet 88 to approximate hole 89; finally, the installation can be completed by fixing the clamp 86 'and the duct 2 together by using a bolt (not shown in the drawings) or the like, after having aligned the fixing eye 88 and the fixing hole 89.

The variant shown in Figures 12 to 14 is interesting in relation to its use in gasoline engines, where the pressure in the duct 2 is relatively low when compared to that found in a direct injection diesel engine.

In this case, a 62 '' fitting similar to that of the previous variant is used. The only differences reside in the fact that the fitting 62 '' comprises a preferably corrugated end 66 that can be coupled to a tubular element 80 ', in particular made of elastomeric material, through the use of a connecting cable 82, being the latter capable of providing a stable coupling between the two components, in particular by compression.

Likewise, the tubular element 80 'is coupled to an inlet 3b' ', also preferably corrugated like the end 66, thus making it possible to use another connecting cable 82 in order to fix the connection between the coupling 80' and said entry 3b ''; said inlet 3b '' is positioned at one end of duct 2 and radially with respect to the latter.

Said coupling 80 'can be suitably made with elastomeric material or plastic or the like, thus making serial production economically advantageous.

Just as with the fitting 62 'described above, the fitting 62' 'is also held integral with the duct 2 by means of a clamp 86' ', which, in this variant, has a substantially straight shape and is coupled to the duct 2 in the same way as the clamp 86 'already described, that is, through the fixing eye 88 and the fixing hole 89, and possibly also through said positioning and / or anti-rotation means 141, 142.

Figures 15 to 17 show another variant of the invention, which differs from the previous one in the fixing means and in the positioning of an inlet 3b '' 'included in the duct 2. In this variant, the inlet 3b' ' 'is located in the middle of the duct 2, as in the second variant described above.

Sensor 1, when in operating condition, is installed within a 62 '''fitting, which it has two retention slots 67 at its outlet.

The latter make it possible to firmly position a clip 8 "'so that it interferes with the annular element 85 comprised in the coupling 80, thereby retaining the latter, stably connecting it to the fitting 62"'.

To ensure proper sealing, suitable sealing elements 59d, such as O-rings or the like, are provided in the coupling 80.

Regarding the connection with the inlet 3b '' ', this variant adopts the same solution already used in the second variant described above.

As in the previous variant, the fitting 62 '' 'is kept integral with the conduit 2 by means of a clamp 86' '', which is identical to the clamp 86 '' described above.

The connection takes place in a direction substantially parallel to the axis of the conduit 2, inserting the coupling 80 into the fitting 62 '' ', and, possibly, making an angular movement around the axis of said connection to couple a positioning element and / or anti-rotation 141 in its seat 142.

It is evident that this variant is advantageous provided that the space available around the duct 2 only allows an installation movement to be carried out parallel to the axis of the duct 2, with the possible addition of said slight angular movement.

Figure 18 shows another variant that uses a fixing clamp 86IV that is independent of a fitting 62IV; Said fitting 62IV is similar to fitting 52 'described in the first variant, although it is longer and comprises a mounting positioner 123.

Preferably, mounting positioner 123 has a parallelepiped shape with rounded corners, and is positioned near the intersection between the different conduits, with its axis of symmetry parallel to that of input coupling 64.

The fixing clamp 86IV has an elongated U-shape, and comprises two housing seats 121, 122 and an opening 124, which are compatible, respectively, with the fitting 62IV, the conduit 2, and the mounting positioner 123. Said seat 121 and said opening 124 are located substantially on the curved portion of the U-shaped bracket, while the seat 122 is located substantially on an intermediate portion of the bracket 86IV.

In the operating condition, the fixing clamp 86IV circumscribes both the fitting 62IV and the conduit 2, thereby keeping them mutually integral. Preferably, the assembly of clamp 86IV - fitting 62IV-duct 2 is held firmly together by means of a quick coupling screw 91, which can tighten the end portion of the U by properly fixing the housing seats 121, 122 around the fitting 62IV and duct 2.

Before mounting bracket 86IV, screw 91 is already installed in bracket 86IV; said screw 91 comprises a ball-head end which, after mounting the clamp 86IV, is snapped into a suitable interconnecting seat obtained as one piece with the clamp. Said interconnecting seat comprises interconnecting teeth that yield elastically during said forced insertion, to hold the spherical end of screw 91. Finally, screw 91 is screwed substantially into a wall of clamp 86IV to pull the opposite end of the shaped clamp. of U, that is, the one with which the spherical head has been interconnected.

In this variant, the connection means between fitting 62IV and conduit 2 comprise a coupling 80, the threaded insert 83 of which is coupled to fitting 62IV, while the other end is coupled to an inlet 3bIV positioned in the center of conduit 2 and radially with respect to the latter; said inlet 3bIV comprises a quick coupling 70 to ensure a firm connection with coupling 80. Figure 19 illustrates a seventh variant of the invention, which turns out to be particularly advantageous when duct 2 comprises one or more blind inlets 3c ', that is, that are not in fluid communication with the conduit 2, arranged radially with respect to the conduit 2. In fact, this variant advantageously allows one of these blind inlets 3c 'to be used to fix on it a fitting 62V similar to the fitting 62IV used in the previously described variant.

To this end, the fitting 62V comprises a fixing clamp 86V made in one piece with said fitting 62V and located below it; said clamp 86V comprises, in its part furthest from the conduit 62V, a plug 86c compatible with one of the blind inlets 3c 'of the conduit 2. It should be noted that, advantageously, no sealing means are required for the plug 86c, since no there is fuel flowing into the blind inlet 3c '.

Also in this variant, the connection between fitting 62V and conduit 2 is made through coupling 80, whose threaded insert 83 is coupled to the fitting 62V, while the other end is coupled to the inlet 3c (where fuel flows) of the conduit 2; This connection is made firm by using a clip 8V similar to the clip 8 '''used in the fifth variant, which, by tightening the conduit 3c, retains a part of the coupling 80 therein.

In this variant, the conduit 3c in which fuel flows is positioned approximately in the center of the conduit 2, although this should not be considered as a limiting element, since those skilled in the art can place the inlet 3c in the most suitable position to along duct 2 in order to optimize the occupied space.

Finally, to facilitate the positioning and maintenance of the clip 8 '' 'in an operating condition, the inlet 3c comprises a suitable seat or openings in the terminal part of said inlet 3c (the one furthest from the conduit 2).

As in the previous variants, also in this case sealing means are provided to prevent any fuel leakage from the connections between the various parts.

Figure 20 illustrates a last variant of the invention, which uses a 62VI fitting that contains the sensor 1 and which is similar to the 62V fitting used in the previous case. This variant differs in the means used to fix the fitting 62VI to the conduit 2. In fact, the fitting 62VI comprises a clamp 86VI made as a single piece with said fitting 62VI (as in the previous variant) and positioned below it.

Clamp 86VI differs from clamp 86 of the second variant shown in figure 7, in the way in which it is connected to conduit 2: in particular, conduit 2 comprises a click-fit or gasket-type snap guide 131, which can be attached to clamp 86VI with a downward motion.

To this end, the clamp 86VI comprises two opposing engagement teeth 86VIb compatible with the engagement seats 131a comprised in the guide 131.

When the fitting 62VI is positioned in conduit 2, the coupling teeth 86VIb undergo elastic deformation until they interconnect with the respective coupling seats 131a, whereby the required lateral sliding movement is not necessary, for example, by the second variant. Furthermore, said gasket-type guide 131 offers the same advantages as guide 86, since it allows the fitting 62VI to be precisely positioned by exerting a movement perpendicular, radial, or possibly parallel in a slidable manner to the axis of conduit 2.

The clamp 86VI comprises a pair of locking tabs 86VIa, which facilitate the positioning process and / or prevent, during installation, the clamp 86VI from penetrating too far into the joint 131, thus complicating the assembly process. in case there is little space available, for example inside an engine compartment of a small car.

Regarding the hydraulic connection means between the fitting 62VI and the conduit 2, this variant uses the same means as the sixth variant, that is, the coupling 80 and the quick coupling 70 positioned in an inlet 3bVI, the latter being equal to entry 3bIV

Figures 21 and 22 illustrate a fitting 92 that does not form part of the invention, and that comprises, in turn, an inlet 93, an inlet duct 93a and an outlet duct 93b, axial or aligned with each other, wherein said outlet conduit 93b is applied directly to an inlet 3d of conduit 2.

This can be used, advantageously, when a sensor 1 ', similar to the sensor 1 described in the previous variants, must be arranged above and in parallel with respect to the conduit 2 for reasons of clearance, or when it is necessary to reduce the tortuosity of the path fuel in order to improve a metering process. Optionally, it is possible to use a connector (a quick connector or a nozzle or the like, or a threaded or bayonet connector), or a soldered joint, to connect the fitting 92 to the 3d inlet.

The configuration of the fitting 92 and the dimensions of the parts to be connected, as well as the proximity to the conduit 2, make it possible, in this case, to support the fitting 92 without any clamp 86, although one can nevertheless be used.

It should be noted that sensor 1 'is slightly different from sensor 1 previously described, since it does not have control and measurement circuitry. In fact, in this variant the control and measurement circuitry must be located remote from the sensor 1 '. This is interesting when said control circuitry is comprised in another electronic circuit of the vehicle, such as an electronic engine management circuit or control unit, which results in obvious economic advantages.

Therefore, the housing 5 and the electrical connector 7 are replaced by a base or housing 95 connected to the element bender 14, from which the electrical conductors or wires 94 extend.

The base 95 is coupled to the seat 90 of the fitting 92, with which it is aligned by means of a positioning rib 96 that will interconnect in a homologous recess 97 present in the fitting 92, thus providing means that guarantee precise positioning to the sensor 1 'with respect to fitting 92.

Preferably, the sensor 1 'is fixed and maintained in its position through suitable fixing means, such as screws (not shown in the drawings) inserted in the pairs of holes 98, 99 provided in the fitting 92 and in the base 95 although, alternatively, other fixing means may be used, such as a quick coupling, a bayonet coupling, a thread or a weld.

Figure 23 is similar to the corresponding one just described, the only difference being the arrangement of sensor 1 ', which, in this case, is positioned substantially perpendicular to conduit 2; Such an arrangement can be interesting when a part of the duct 2 ', which includes the inlet 3b, is only accessible from a direction perpendicular to said duct 2.

The fitting 92 'comprises a fuel inlet 93' and a seat 90 'that houses the sensor 1', which have the same functions as the inlet 93 and seat 90 previously described, but are positioned in a different way. In fact, the inlet 93 'has its axis parallel to that of the duct 2, while the axis of the seat 90' is perpendicular to the axis of said duct 2, thus making it possible to position the sensor 1 'in such a way that is substantially perpendicular to conduit 2, which results in the aforementioned advantages.

The connection between the fitting 92 'and the conduit 2 is made in a similar way to that described for the previous variant, that is, a connector can be used (a quick connector or a nozzle or the like, or a threaded bayonet connector) or a welded joint.

As mentioned above, the present invention is not only applicable to the "bending element" sensors that have been considered so far, but also to other types of sensors, provided that they are suitable for detecting properties of the combustible fluid. as previously explained.

Thus, for example, Figures 27 and 28 show, respectively, an acoustic sensor 1 'and an optical sensor 1' '.

In the first case shown, the sensor 1 'comprises a transceiver 112 for acoustic waves, such as ultrasound waves or sounds, whose shape and / or coupling are similar to those of the "bending element" sensor of the previous examples; therefore, said sensor 1 'comprises or is associated with a fitting body (5, 62, 62' ......) adapted to be connected and / or fixed to the fuel conduit 2 in a completely similar way to already described, to which we refer for brevity reasons.

Substantially, the waves emitted with a pre-established frequency by the transceiver 112 are reflected by the combustible fluid and are then received by the same transceiver, to which is associated an electronic board known per se (not shown in figure 27 because it is similar to the one already described).

Next, the acoustic signal reflected by the fluid is processed in order to provide information on the density and / or viscosity of the combustible fluid, as well as on its speed and the like; For this purpose, the speed of propagation of sound in the medium, the Doppler effect, and so on, can be used.

In the second case shown in figure 28, on the other hand, sensor 1 '' is an optical sensor and comprises a photocell 114 and a light source 115 optically coupled to the first and positioned at the end of a support arm 113.

The latter can be used, advantageously, to supply power to the source 115, which can be of any type suitable for operating in the combustible fluid, for example an LED. Sensor 1 '' makes it possible to detect the properties of the fuel circulating in duct 2, such as density, or the presence of gas bubbles or phases of water emulsified in the fuel, using, in this case, optical parameters, such as refraction and reflection of light rays by the combustible fluid.

Also in this case, the shape of the sensor 1 '' is similar to that used in the other embodiments, comprising or being associated with a fitting body (5, 62, 62 '...), so that it can be apply to a fuel line 2 according to the previous teachings, to which we refer to avoid inopportune repetitions.

More generally, it can be stated that, in the present invention, any sensor comprising at least one active element, such as an electrode or an arm as the arm, can be advantageously used. of support 113, extending in the fuel conduit 2 or in the fitting body 52, 52 ', 62 and so on, as mentioned above.

Thus, for example, figure 29 shows a sensor 1 '' 'comprising a pair of axial electrodes 124, 125, the first of which has a tubular shape and is external to the second, which consists of a rod or wire. conductive metallic; in the outer electrode 124 there are holes or openings 130 for the passage of the combustible fluid, whose electrical properties, such as resistivity, capacity, etc., can be detected according to the prior art (in fact, axial sensors are known, for example, from US 4,806,847, where they are nevertheless used for tanks, or in any case not in fuel lines).

Similar considerations apply to the variants shown in Figures 32, 32a and 33, 33a, which deal with a sensor 1'v associated with a fitting body (62 ') and / or a fuel line 2 according to a solution similar to that of Figures 9, 10 and 12; Also in this case, for brevity reasons we refer to the previous explanation with a view to obtaining more details. What should be added to the above description is that, in this case, the sensor 1'v comprises a pair of projecting elements 134 and 135, which, in a preferred embodiment, consist of two electrodes, but which can be probes. or other suitable elements to detect properties of the combustible fluid.

As shown in the drawings, the sensor 1'v is housed in the fitting 62 ', in one case (Figures 30, 30a) in the seat 60 at the end of the fitting 62', which is aligned along a longitudinal axis of the fitting 62 'with the initial part of the coupling 80 connected to the same fitting, while, in the other case, the position of the inlet 63 and of the seat 60 with the sensor 1'v is reversed, that is, the seat 60 is orthogonal or it is inclined with respect to said longitudinal axis.

The latter can also be considered as the axis of the fuel outlet portion of the fitting body 62 ', to which the initial portion of the coupling 80 is connected.

Finally, numerous combinations of the individual characteristics of the different variants can be devised in order to create additional variants, even different from those illustrated herein by way of example, allowing those skilled in the art to meet specific design requirements. , although without departing from the teachings of the present patent application.

In one possible combination, the fixing or support means can be reversed; In other words, the parts associated with the sensor 1, 1 'or with the fitting 52, 52' 62, 62 ', 62' ', 62' '', 62IV, 62V, 62VI, 92, 92 'can be associated with conduit 2 , or vice versa.

All possible variants that are apparent to those skilled in the art will continue to be included within the scope of the following claims.

Claims (16)

1. Arrangement of a device for detecting at least one parameter of a fuel or mixtures thereof supplied to an internal combustion engine, comprising sensor means (1, 1 ') to be in contact at least partially with the fuel or mixtures thereof, the sensor means (1, 1 ') being externally associated to a conduit (2) of the type "fuel conduit", "common conduit" and the like, to supply the fuel or mixtures thereof to the engine, being the sensor means (1, 1 ') housed in a seat of a body or fitting comprising a coupling or tubular outlet element (80) downstream associated or connected to an inlet (3b) of the fuel conduit (2), and because the arrangement comprises fixing or support means (86, 86 ', 86' ', 86' '', 86IV, 86V, 86VI 88, 89) to mechanically fix and / or support the sensor means (1, 1 ' ) or its housing seat (50, 60, 90, 90 ') or the fitting (52, 52' 62, 62 ', 62' ', 62' '', 62IV, 62V, 62VI, 92, 92 ') over the fuel conduit (2), substantially adjacent to the fuel conduit in connection with at least two distinct or separate points, one in a substantially intermediate or terminal position of the conduit, and another in at least one point substantially located in a terminal or opposite or intermediate position of the fuel conduit, so that the conduit (2) and the sensor (1) will behave substantially as a rigid part. Arrangement according to claim 1, in which the sensor means (1, 1 ') are located totally or mainly outside the conduit (2), and in which said sensor means (1, 1') are arranged according to the minus one of the following alternatives: - adjacent to or next to the duct (2), extending predominantly parallel to the axis thereof; - adjacent or next to the conduit (2), predominantly extending radially with respect to the axis of said conduit (2). Arrangement according to claim 1 or 2, in which the sensor means (1, 1 ') are associated with or integrated in a housing (5, 95) or a fitting (52, 52' 62, 62 ', 62' ' , 62 '' ', 62IV, 62V, 62VI, 92, 92') in fluid communication with said conduit (2) to supply the fuel or mixtures thereof. Arrangement according to claim 3, in which the sensor means (1, 1 ') or the housing (5, 95) or the fitting (52, 52', 62, 62 ', 62 ", 62"' ' , 62IV, 62V, 62VI, 92, 92 ') are removably associated or fixed to the fuel duct (2), in particular at one end thereof or in an adjacent, parallel or radial position with respect to it. Arrangement according to claim 3 or 4, in which a fuel path is defined in the fitting (52, 52 ', 62, 62', 62 ", 62" '', 62IV, 62V, 62VI, 92, 92 ') extending between at least one inlet (53, 54, 63, 64, 93, 93') and one outlet (56, 56 ', 58, 80, 80'), in which a seat (50 , 60, 90, 90 ') to house the sensor means (1, 1') is located at least partially along said path or in an intermediate position. Arrangement according to any of the preceding claims, in which said coupling or tubular outlet element (80) and said fixing or support means (86, 86 ', 86 ", 86" ", 86IV, 86V, 86VI , 88, 89) connect the sensor means (1, 1 ') to the fuel conduit (2) in correspondence with at least two different locations thereof. Arrangement according to claim 6, in which the fixing or support means (86, 86 ', 86' ', 86' '', 86IV, 86V, 86VI, 88, 89) comprise a clamp (86, 86 ' , 86 '', 86 '' ', 86IV, 86V, 86VI). Arrangement according to claim 6 or 7, in which the fixing or support means (86, 86 ', 86' ', 86' '', 86IV, 86V, 86VI, 88, 89), or at least one part of them can be removably attached to the fuel conduit (2). Arrangement according to any one of the preceding claims, wherein the fixing or support means (86, 86 ', 86 ", 86"' ', 86IV, 86V, 86VI, 88, 89) for mechanically fixing and / or support the sensor means (1, 1 ') or its housing seat (50, 60, 90, 90') or the fitting (52, 52 ', 62, 62', 62 '', 62 '' ', 62IV, 62V, 62VI, 92, 92 ') comprise a quick coupling (70, 81) that substantially allows installation through a single insertion movement, in particular along an axis substantially parallel or perpendicular to that of the conduit (2) , said quick coupling (70, 81) being arranged in at least one of the following positions: - at an inlet (3a, 3b, 3b ', 3b' ', 3b' '', 3bIV, 3bVI, 3c, 3d) of the duct (2), - at the outlet of the fitting (62) or in an intermediate part of the fitting (62). Arrangement according to claim 9, in which the quick coupling is of the type designed for hydraulic lines. Arrangement according to any of claims 3 to 10, comprising a coupling (80, 80 ') for connection to the fuel line (2), the ends of which are respectively coupled to the fitting (62, 62', 62 '', 62 '' ', 62IV, 62V, 62VI) and to the fuel line (2), preferably in a removable manner. Arrangement according to any of the preceding claims, in which the sensor means (1, 1 ') are of one or more of the following types: electrical, piezoelectric, vibrating, magnetic, electromagnetic, optical, acoustic, resistive, capacitive , inductive. Arrangement according to claim 12, in which the sensor means (1, 1 ') comprise a piezoelectric element or bending element (14), in particular adapted to detect variations in fuel viscosity, or the sensor means (1, 1 ') comprise an acoustic sensor, such as an ultrasound transmitter / receiver (112), in particular adapted to detect variations in the speed of sound propagation in the fuel, or the sensor means (1, 1') comprise an optical sensor (114, 115), such as an optical receiver (114) and a light source or transmitter (115), in particular adapted to detect variations in fuel turbidity. Arrangement according to any of claims 5 to 13, comprising at least one element (8) that cooperates with the sensor means (1, 1 ') to fix the latter in the respective housing seat (50, 60, 90 , 90 ') or on the fitting (52, 52', 62, 62 ', 62' ', 62' '', 62IV, 62V, 62VI, 92, 92 '), such as a clip or hook or weld or a tail. A conduit (2) for supplying fuel to an internal combustion engine, comprising an arrangement according to any one of claims 1 to 14, and including at least one fuel inlet (3a, 3b, 3b ', 3b' ' , 3b '' ', 3bIV, 3bVI, 3c, 3d) and a plurality of fuel outlets (4), characterized in that it comprises or is associated with coupling means (3a, 3b, 3b', 3b '', 3b '' ', 3bIV, 3bVI, 3c, 3d, 8, 58, 70, 80, 80', 81, 82, 86, 86 ', 86' ', 86' '', 86IV, 86V, 86VI, 87) provided of an external sensor (1, 1 '), such as hydraulic or fluid coupling means (3a, 3b, 3b', 3b '', 3b '' ', 3bIV, 3bVI, 3c, 3d, 58, 70, 80, 80 ', 81), preferably also comprising fixing or support means (8, 58, 82, 86, 86', 86 '', 86 '' ', 86IV, 86V, 86VI, 87) for a device of fuel detection (D). Duct according to claim 15, in which the fixing or support means (86, 86 ', 86 ", 86"' ', 86IV, 86V, 86VI, 88, 89) comprise one or more of the following alternatives: - a quick coupling (70, 81) that substantially allows installation through a single insertion movement, in particular along an axis substantially parallel or perpendicular to that of the duct (2), - a thread (58) arranged at one end of the conduit; - plastic material molded into one end of the duct; - a clamp (86, 86 ', 86' ', 86' '', 86IV, 86V, 86VI).