FR2725245A1 - FUEL SUPPLY DEVICE FOR A MOTOR VEHICLE WITH PRESSURE REGULATION - Google Patents

Abstract

A fuel feed device for an internal combustion engine, including a pump (10) designed to draw fuel from a tank (12) and an element (30) responsive to the pressure in a non-bypass feed line (16) connected to the discharge side of the pump (10) for controlling the actuation of the pump (10). Said device includes a pressure-reducing regulator (40) arranged in series on the non-bypass feed line (16) connected to the discharge side of the pump (10), upstream from the site (14) where the fuel is used.

Description

 The present invention relates to the field of fuel supply devices for internal combustion engines on motor vehicles.

 As shown diagrammatically in the appended FIG. 1, the conventional fuel supply systems of internal combustion engines include a pump 10 which takes the fuel from a tank 12, and directs this fuel towards the zone of use, that is to say generally towards the injectors 14, via a supply pipe 16. The excess fuel is returned to the tank 12 using a return pipe 18. The pump 10 generally comprises an upstream filter 11. In addition a downstream filter 13 is generally placed at the outlet of the pump 10, on the supply pipe 16.

 This conventional arrangement, known as a loop, shown in FIG. 1, has the drawback of leading to a heating of the fuel passing through the zone of use 14 and brought back to the tank 12 by the return duct. In addition, it requires a significant permanent flow of fuel at the outlet of the pump 10, therefore a non-negligible consumption of electric current.

 To avoid this heating of the fuel and consequently decrease the emissions of fuel vapors accumulated in the tank 12, it has been proposed, as shown diagrammatically in FIG. 2, so-called dead-end supply systems, in which the back 18 is deleted. In this case, as shown diagrammatically in FIG. 2, a pressure regulator 20 working in bypass is preferably integrated on the supply line 16. This pressure regulator 20 ensures the return of the excess fuel, towards the reservoir 12. This pressure regulator 20 has its inlet connected to the supply line 16, generally downstream of the filter 13, by a bypass duct 15. The outlet of the regulator 20 opens into the reservoir 12.

 However, such systems are not entirely satisfactory. Indeed, such systems also require a significant permanent flow of fuel at the outlet of the pump, therefore a significant consumption of electric current. In addition, these systems in which the pump 10 operates continuously are noisy and require pumps having a long service life.

As shown diagrammatically in FIG. 3, other dead-end supply systems have also been proposed which do not include a duct 15 or a pressure regulator in bypass, but in which the electrical supply to the pump 10 is controlled by a sensor 22 sensitive to the pressure prevailing in the supply line 16 connected to the outlet of the pump. The module 24 supplying the pump 10, controlled by the sensor 29, is designed to impose a pressure at the outlet of the pump 10 equal to the operating pressure required at the injectors 14. Systems in accordance with FIG. 3 are described for example in documents US-A-5237975, EP-A-0024645, EP-A-0423636,
EP-A-0289210 and WGA-88/01344. This solution certainly has the advantage of reducing the amount of fuel passing through the pump as well as the amount of fuel passing through the filter. However, it is not entirely satisfactory. On the one hand, it requires a high cost sensor 22 because of the required measurement precision. On the other hand, it does not always lead to satisfactory pressure regulation.

 The present invention now aims to improve the known fuel supply devices.

 This object is achieved according to the present invention by means of a fuel supply device for an internal combustion engine comprising a pump designed to draw fuel from a tank and a pressure-sensitive element prevailing in a supply line without connected bypass. at the pump outlet and suitable for controlling the commissioning of the pump, characterized in that it comprises a pressure regulator placed in series on the supply line without branch connected to the pump outlet, upstream of the fuel use site.

 Other characteristics, aims and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawings, given by way of nonlimiting examples and in which - FIGS. 1 to 3 previously described illustrate the state of the art, - Figures 4 and 5 show schematically, in the form of functional blocks two alternative embodiments of a supply system according to the present invention, - Figure 6 shows a schematic view in longitudinal section of a pressure sensor capable of being used in the context of the present invention, and - Figure 7 shows a schematic view in longitudinal section of a pressure regulator capable of being used in the context of the present invention.

 We see in Figures 4 and 5 attached, an assembly comprising a fuel tank 12, a pump 10 associated with an upstream filter 11, and a supply line 16 connected to the outlet of the pump 10 and designed to direct fuel to a site 14 of use, for example an injector manifold.

 It will be noted on examining FIGS. 4 and 5 that according to the invention, the system further comprises a sensor 30 sensitive to the pressure prevailing in the supply line 16 and a regulator regulator 40 placed in series on the supply line. supply 16, upstream of the site of use 14.

 The pressure sensor 30 is connected to a control module 50 which controls the pump 10 itself.

 The fuel tank 12 and the pump 10, preferably electric, can be the subject of numerous variants. These will therefore not be described in more detail below.

 The pressure sensor 30 is preferably formed of a simple pressure switch.

 FIG. 6 appended shows a preferred embodiment of such a pressure switch 30.

 The contactor illustrated in this FIG. 6 comprises a housing 3 1 divided into two chambers 32, 33 by a deformable membrane 34 urged on one side by a calibrated spring 35, and on the other by the pressure of the fuel to be measured prevailing in the supply line 16.

 The sensor 30 also comprises two electrical contacts 36, 37 whose connection state depends on the position of the diaphragm 34, therefore on the fuel pressure prevailing in the supply line 16.

 For this, one of the contacts 36 is for example secured to the housing 31 while the second contact 37 is secured to the membrane 34.

 More precisely, according to the nonlimiting embodiment shown in FIG. 6, a first chamber 32, preferably sealed, houses the spring 35 and the two electrical contacts 36, 37. The second chamber 33 is provided with a nozzle 38 allowing to put said chamber 33 in communication with the supply line 16.

 The operation of such a pressure switch 30 is simple: the state of electrical connection between the contacts 36, 37 switches when the fuel pressure in the chamber 33, therefore the pressure in the supply line 16, crosses a threshold.

 More specifically, according to the preferred embodiment shown in Figure 6, the electrical contacts 36 and 37 are adapted to be connected, which corresponds to a switch in the closed state, when the fuel pressure in the supply line 16 is less than a predetermined threshold.

 Of course, a reverse arrangement can be adopted, that is to say that a configuration of separate electrical contacts 36, 37 can be provided when the fuel pressure in the chamber 33 is below the aforementioned threshold, subject to adapting consequently, the control module interposed between the pressure sensor 30 and the pump 10.

 The supply line 16 is a line without branching, or dead end, connected to the outlet of the pump 10; that is to say that the supply line 16 does not include any bypass making it possible to bring excess fuel back to the tank 12.

 The regulator regulator 40 is, as indicated previously, placed in series on the supply line 16 between the pump 10 and the site of use of fuel 14.

 The regulator regulator 40 can be the subject of different embodiments.

 Illustrated in Figure 7, a preferred embodiment.

 We see in this figure 7, a regulator regulator 40 comprising a housing 41 divided into two chambers 42, 43 by a deformable membrane 44 sensitive to pressure.

 More specifically, a first chamber 42 houses a calibrated spring 45 which urges the membrane 44.

 The second chamber 43 has an inlet 46 formed on a nozzle 47 and at least one outlet 48. In addition, the inlet 46 is controlled by a valve 49. This valve 49 has a movable element 51 linked to the membrane 44 and which cooperates with a seat 52 linked to the housing 41.

 The membrane 44 is biased on one side by the calibrated spring 45 and on the side order by the fuel pressure prevailing in the chamber 43.

 The valve 49 provided on the inlet 46 opens when the pressure in the chamber 43 is less than the calibration force of the spring 45 and on the contrary the valve 49 closes when the pressure in the chamber 43 becomes greater than the calibration of the spring 45.

 Thus, the pressure regulator 40 makes it possible to obtain a constant pressure in the chamber 43.

 The nozzle 47 which forms the inlet 46 is connected to the part of the supply conduit 16 coming from the pump 10. The outlet 48 is in turn directed towards the site of use 14 by any suitable connection.

 Of course, it is necessary to provide sealing elements at the connections between the end piece 47 forming the inlet 46 and the supply line 16 on the one hand, and between the outlets 48 and the piping going to the use site 14, for example an injector manifold, on the other hand.

 In FIGS. 4 and 5 appended, a control module for the pump 10 is shown diagrammatically under the reference 50.

 The setting pressure of the pressure sensor 30 is greater than the operating pressure required at the outlet of the pressure reducing sensor 40.

 Preferably, the setting pressure of the pressure sensor 30, which corresponds to the pressure required in the supply line 16 is at least 200 mbar higher than the pressure required at the site of use 14 which also corresponds to the pressure of the regulator regulator 40.

 The system preferably comprises, and in a manner known per se, a filter 13 on the supply line 16. The filter 13 can be located downstream of the pressure sensor 30 as illustrated in FIG. 4, or upstream of this pressure sensor 30 as illustrated in FIG. 5, which makes it possible to compensate for the possible and variable pressure drop of the filter 13 (by clogging), without increasing the pressure difference necessary for the proper functioning of the pressure reducing regulator 40 ..

 Insofar as the filter 13 is traversed only by the fuel used, its size can be reduced compared to the known prior arrangements.

 This can facilitate in particular the incorporation of the filter 13 into the reservoir 12 as shown diagrammatically in FIG. 5, or even on a base linked to a wall of this reservoir 12.

 In fact, the pressure sensor 30 and / or the filter 13 can each be placed either inside the tank 12, or outside the tank 12, or even on a wall of the latter.

 Preferably, the regulator regulator 40 is located at the site of use, or preferably on the injector rail.

 Insofar as the pressure reducer 40 located near the site of use 14 directly defines the pressure of use, it is possible to use supply conduits 16 of smaller sections than in conventional systems, without fear of harmful influences. caused by possible online pressure drops.

 It will be noted that according to the invention, the pump 10 is also traversed only by the fuel actually used. The current consumption of the pump therefore remains low. In addition, the lifespan of the pump is extended compared to the known prior arrangements comprising a bypass on the supply line 16.

 Preferably the pressure sensor delivers all or nothing information, calibrated by a pressure threshold, directly on the power stage controlling the pump 10, this pressure threshold being chosen slightly higher than the pressure of use of the fuel by the engine. as previously stated.

 The chamber 42 housing the calibration spring 45 of the regulator expander 40, can be a closed chamber as illustrated in FIG. 7, or an open chamber allowing this chamber 42 to be placed at a reference pressure, for example atmospheric pressure or else the pressure of the intake manifold.

 In a manner known per se, the drawing assembly comprising the pump 10 can be equipped with a fuel gauging system.

 The invention also relates to tanks equipped with the aforementioned supply system.

 Of course the present invention is not limited to the particular embodiments which have just been described but extends to any variant in accordance with its spirit.

 According to another advantageous characteristic of the present invention, the all-or-nothing information, calibrated with respect to a pressure threshold, coming from the pressure sensor 30, is applied to the engine control computer 60, as illustrated in FIGS. 4 and 5.

 This computer 60 can also integrate the aforementioned pump control module 50.

 Thus the computer 60 can use the information from the sensor 30 to establish the diagnosis of the fuel supply system.

 This diagnostic is carried out according to strategies for monitoring the pressure in the fuel system (monitoring the pressure build-up time after switching on, maintaining the fuel pressure after an engine shutdown phase, constant pressure or maintained within a predetermined range ).

 This diagnostic function can also be used alone, however, preferably the fuel circuit pressure information from the pressure sensor 30 is also used to control the fuel pump 10 and allow savings in electrical energy consumption as indicated above. This architecture not only allows a gain in the number of sensors used, but it also makes it possible, by integrating the piloting function of the fuel pump 10 into the engine control system 60, to reduce the cost of the complete system (a single control electronics 60, a single source of information), and to obtain more complete control strategies (additional corrections possible thanks to new information) and simpler diagnosis (reaction recognized following a request from the piloting function).

 The use of information from the pressure sensor 30 makes it possible to diagnose the fuel supply system by the engine control system (leaks on the injection components 14, proper functioning of the components).

 It also makes it possible to fulfill the new depollution standards which impose a severity of the pollutants emitted, as well as a diagnosis of all the actuators involved in the preparation of the mixture.

Claims (16)

 1. An internal combustion engine fuel supply device comprising a pump (10) designed to draw fuel from a tank (12) and a pressure-sensitive element (30) prevailing in a supply line (16) without bypass connected to the pump output (10) and adapted to control the commissioning of the pump (10), characterized in that it comprises a pressure regulator (40) placed in series on the supply line without bypass (16) connected to the outlet of the pump (10), upstream of the fuel use site (14).  2. Device according to claim 1, characterized in that the pressure-sensitive element (30) is a pressure switch.  3. Device according to one of claims 1 or 2, characterized in that the pressure switch (30) delivers an all-or-nothing electrical signal, calibrated with respect to a pressure threshold, on the power stage of a electric pump (10).  4. Device according to one of claims 1 to 3, characterized in that the tilting threshold of the pressure-sensitive element (30) is greater than the pressure required to use the fuel.  5. Device according to one of claims 1 to 4, characterized in that the tilting threshold of the pressure-sensitive element (30) is at least 200 mbar higher than the pressure required to use the fuel .  6. Device according to one of claims 1 to 5, characterized in that the element (30) sensitive to pressure is formed by a pressure switch comprising a housing (31) divided into two chambers (32, 33) by a membrane (34) subjected on one side to a calibrated spring (35) and on the other side to the pressure prevailing in the supply line (16), and moreover comprising two electrical contacts (36, 37) whose state of electrical connection depends on the fuel pressure applied to the membrane (34).  7. Device according to claim 6, characterized in that the pressure switch (30) forms a closed electrical switch for an input fuel pressure below the setting threshold.  8. Device according to one of claims 1 to 7, characterized in that the pressure reducer (40) comprises a housing (41) divided into two chambers (42, 43) by a membrane (44) sensitive to pressure, one of the chambers having at least one inlet (46) controlled by a valve (49) and one outlet (48).  9. Device according to claim 8, characterized in that the pressure reducer (40) has a closed chamber (42) which houses a calibrated spring (45).  10. Device according to claim 8, characterized in that the holder regulator (40) has a chamber (42) which houses a calibrated spring (45) and which has an opening making it possible to connect this chamber (42) to a pressure of reference, for example atmospheric pressure or the pressure of an intake manifold.  11. Device according to one of claims 1 to 10, characterized in that the regulator regulator (40) is located near the site of use (14), advantageously on a rail of injectors.  12. Device according to one of claims 1 to 11, characterized in that it comprises a filter (13) located upstream of the element (30) sensitive to the pressure on the pipe (16) connected to the outlet of the pump (10).  13. Device according to one of claims 1 to 12, characterized in that the information from the pressure-sensitive element (30) is applied to an engine control computer (60) for diagnostic purposes. fuel supply system.  14. Device according to claim 13, characterized in that the engine control computer (60) integrates the module (50) for controlling the pump (10).  15. Device according to one of claims 13 or 14, characterized in that the engine control computer (60) establishes a diagnosis from information from the element (30) sensitive to pressure on the basis of l at least one of the following parameters: pressure build-up time after switching on, maintenance of the fuel pressure after an engine shutdown phase, constant pressure or maintenance within a predetermined range.  16. Tank equipped with a supply device according to one of claims 1 to 15.