EP2898213A1

EP2898213A1 - Device for measuring an amount of fluid injected by an injector

Info

Publication number: EP2898213A1
Application number: EP13779621.5A
Authority: EP
Inventors: François SCHMIDT
Original assignee: EFS SA
Current assignee: EFS SA
Priority date: 2012-09-19
Filing date: 2013-09-18
Publication date: 2015-07-29
Also published as: FR2995640B1; JP2015529777A; FR2995640A1; WO2014044967A1; CN104641103A

Abstract

The invention relates to a device (1) for measuring an amount of fluid injected by an injector, which comprises: a measurement chamber (2), into which the fluid is injected; a device (3) for injecting the fluid into said measurement chamber (2); and at least one pressure sensor (4) placed in said measurement chamber (2) and suitable for measuring the pressure in said measurement chamber (2). Said device is characterized in that the measurement chamber (2) has a generally ellipsoidal shape, particularly a rotationally ellipsoidal shape, having first and second focal points (F1, F2). Said casing is also characterized in that the injection device (3) comprises an injection opening (32) provided on the first focal point (F1) of said measurement chamber (2) and in that the pressure sensor (4) is provided on the second focal point (F2) of said measurement chamber (2). The present invention is useful in the field of fuel injection systems for heat engines.

Description

Device for measuring a quantity of fluid injected by an injector

The present invention relates to a device for measuring a quantity of fluid injected by an injector.

The present invention relates more particularly to a device for measuring a quantity of fluid injected intermittently or blow by blow by an injector.

The measuring device finds particular application in fuel injection systems, used in combustion engines, in the form of a device for measuring a quantity of fuel injected. However, the present invention is not limited to such application in thermal engines, but may find applications in other areas of fluid quantity measurement, in liquid or gaseous form.

In the field of fuel injection systems, it is known, in particular from document FR 2 795 139 A1, to use a measuring device comprising a measuring chamber into which the fluid is injected, a device for injecting the fluid. in the measuring chamber, a pressure sensor and a temperature sensor arranged in the measuring chamber and adapted to respectively measure the pressure and the temperature prevailing in this measuring chamber.

In other words, it is customary to use a closed measuring chamber, in which the fluid is injected, and in which at least the pressure variation is measured and, in addition, the temperature.

However, the Applicant has observed that a difficulty in the measurement of pressure variations lies in the fact that the measurement chamber is the seat of pressure waves which limit the precision when one seeks to measure such pressure variations for small ones. quantities of fluid injected into the measuring chamber intermittently or piecemeal (in the form of pulses) as is the case in fuel injection systems. In other words, the essential problem of these extremely transient pressure measurements is that pressure waves reflected in the measuring chamber make the measurement extremely difficult and inaccurate.

The present invention aims to improve the accuracy of the measurement of the pressure variation in the measuring chamber by attenuating the disturbing pressure waves.

For this purpose, it proposes a device for measuring a quantity of fluid injected by an injector comprising a measurement chamber in which is injected the fluid, a device for injecting the fluid into said measuring chamber, at least one pressure sensor disposed in said measuring chamber and adapted to measure the pressure in said measuring chamber, said device being remarkable in that that the measuring chamber has a generally ellipsoidal shape, in particular of the ellipsoidal type of revolution, having a first and a second foci, in that the injection device comprises an injection orifice positioned on the first focus of said measuring chamber , and in that the pressure sensor is positioned on the second focus of said measuring chamber.

For an ellipsoid with two foci, the path length between the two foci after a single reflection on the envelope of the ellipsoid is constant regardless of the location of the reflection point on the envelope.

Thus, inside the ellipsoidal measuring chamber with two foci (and therefore non-spherical), the pressure wave paths between the starting point (injection orifice located at the first focus) and the measuring point (sensor pressure located on the second focus) all have the same length after a first reflection on the inner wall of the measuring chamber. Thus, the fluid is injected at the first focus of the ellipsoid and the pressure measurements are made at the second focus. In this way, the pressure waves will propagate between their source (injection orifice located at the first focus) and their arrival (pressure sensor located on the second focus) along paths of the same length and therefore with equivalent delays after a first reflection on the inner wall of the measuring chamber, thus limiting the harmful effect of the pressure waves and improving the accuracy of the measurement.

According to one feature, the device further comprises a temperature sensor disposed in the measuring chamber and adapted to measure the temperature in said measuring chamber, and this temperature sensor is also positioned on the second focus of said measuring chamber, adjacent to the pressure sensor.

In this way, the accuracy of the temperature measurement is also increased by the location of this temperature sensor on the second focus.

According to another characteristic, the device further comprises a device for emptying the measuring chamber having a drain orifice also positioned on the second focus of said measuring chamber, adjacent the pressure sensor. In this way, the fluid is drained directly at the point of measurement and output pressure waves, improving the accuracy of the measurement by limiting the creation of disruptive waves.

A focus certainly constitutes a specific point location, and it is clear that the location of the injection port, the pressure sensor, the temperature sensor and / or the drain orifice on the home concerned means a location on the home even in the immediate vicinity of the punctual focus.

In a particular embodiment, the device further comprises first and second hollow supports sealingly traversing the measuring chamber and having free ends positioned respectively on the first and second foci of said measuring chamber and supporting respectively the orifice of injection and the pressure sensor.

Such supports make it possible to hold the pressure sensor and the injection orifice in place on the respective foci, with the injection duct of the injection device extending at least partly inside the first support. and with the connections of the pressure sensor (for an electrical connection with a control and / or supply system) arranged at least partly within the second support.

Advantageously, the second support also supports at its free end the temperature sensor and / or the drain orifice, thus making it possible to take advantage of the second support to position the pressure sensor with the temperature sensor on the second focus. / or the drain port, the second support for accommodating within it the links of the temperature sensor (for an electrical connection with a control system and / or supply) and / or the drain line.

In a particular embodiment, the device comprises seals interposed between the supports and the measuring chamber, preferably of the fluid seal type.

These seals disposed on the passageways of the supports through the measuring chamber are advantageously made so as to avoid transmitting the vibrations from the outside towards the inside of the measuring chamber.

The use of fluid seals is particularly advantageous for reducing the vibrations that could transmit the supports, and in particular the first support which partially supports the injection device which, in the case a fuel injector, is a real shock generator; such vibrations being sources of disturbance for the measurement of the pressure by the pressure sensor, and therefore for the accuracy of the measurement. However, such fluid seals can eliminate any rigid mechanical contact between the supports and the measuring chamber.

According to a possibility of the invention, the device further comprises a screen disposed inside the measuring chamber and interposed between the two homes on the virtual line directly connecting the two homes between them.

In this way, this screen makes it possible to eliminate the pressure waves flowing directly between the two foci in order to favor only those that have made at least a first reflection on the internal walls of the measurement chamber.

Preferably, this screen is made of a material absorbing pressure waves, or is covered with a coating made of such a material, in order to cope with a rapid attenuation of these direct pressure waves.

Advantageously, the screen is held suspended between the two homes with one or more links fixed on the measuring chamber and on the screen.

According to another possibility of the invention, the device furthermore comprises an external enclosure inside which the measurement chamber is kept suspended, without direct contact between the external enclosure and the measurement chamber, with one or more links fixed on the measuring chamber and on the outer enclosure, preferably flexible links, elastic or shock absorbers.

Hanging the measuring chamber inside an external chamber has several advantages: the measuring chamber is thus decoupled from external influences and in particular from shocks and vibrations, and the design of the measuring chamber is simplified because it is the outer enclosure that will withstand the static pressure of the fluid, which pressure can typically rise up to 200 bar in applications with fuel injection systems for a heat engine.

In addition, it is advantageous to provide a safety valve in the external enclosure, calibrated slightly above the maximum operating pressure, for example at 220 bar for the 200 bars mentioned above, in order to discharge the external enclosure by case of overpressure. In this configuration with external speaker, it is interesting to note that:

- If the aforementioned joints are of the fluid seal type, the balance between the measuring chamber and the outer enclosure is automatically leaked at these joints; in practice, these fluid seals perform a low-pass filtering on the pressure in the measuring chamber and then take into account and the rapidly varying pressure in the measuring chamber and the slower-varying pressure in the outer enclosure;

- if the aforementioned joints are of the solid seal type made from a tight and flexible material, it is preferable to provide a safety valve in the measuring chamber, to allow a safety discharge from the measuring chamber to the external enclosure in case of overpressure.

According to another advantageous characteristic of the invention, the device further comprises a system for regulating the pressure inside the external enclosure.

In a simplified and less expensive embodiment, the device does not include this external enclosure and, in this case, the measurement chamber is in direct contact with the environment and with the fluid injection system which constitutes a source of shocks and of vibrations. In addition, the measuring chamber must be designed to withstand the static pressure of the fluid which, as a reminder, can rise up to 200 bar with the fuel injection systems. It is also preferable, in this simplified version, to provide a safety valve in the measuring chamber, to allow a safety discharge of the measuring chamber to the outside in case of overpressure.

Advantageously, it is conceivable to provide a Helmholtz resonator which opens on a wall of the measurement chamber to attenuate the waves. Note that the use of such a Helmholtz resonator in a measurement chamber could also be considered with measuring chambers having shapes other than the ellipsoidal shape.

The use of such a Helmholtz resonator is relatively effective for at least the resonance frequency of the resonator, so that a significant improvement of the attenuation of the waves can be obtained by employing several Helmholtz resonators which have frequencies of different resonance, so as to be able to attenuate the main disturbing frequencies within the measuring chamber.

The advantage of using one or more Helmholtz resonators compared to a posteriori digital processing on the measurements carried out by the pressure sensor, lies in the fact that the resonance frequency of the resonator moves as the frequencies that one seeks. attenuating in the measuring chamber when the density and compressibility of the liquid vary; these variations occurring continuously due to changes in temperature, pressure and, in the longer term, aeration and / or aging of the fluid. Thus, the Helmholtz resonator adapts itself to the inherent characteristics of the fluid.

The invention also relates to a device according to the invention which constitutes a device for measuring a quantity of fuel injected by an injector used in a heat engine.

Thus, the invention also relates to the use of such a device as a device for measuring a quantity of fuel injected by an injector used in a heat engine.

Other characteristics and advantages of the present invention will appear on reading the following detailed description of two nonlimiting exemplary embodiments, with reference to the appended figures in which:

- Figure 1 is a schematic view of a first measuring device according to the invention;

FIG. 2 is a schematic view of a second measuring device according to the invention; and

- Figure 3 is a schematic view of a third measuring device according to the invention.

The present invention will be described with reference to FIGS. 1 to 3 which respectively disclose a first, a second and a third embodiment of the invention and, unless explicitly or implicitly indicated, organs, parts, devices or structural or functional elements. identical or similar will be designated by identical references in Figures 1 to 3.

With reference to FIGS. 1 to 3, a measuring device 1 according to the invention, designed for measuring a quantity of fluid injected by an injector, comprises: a measurement chamber 2 in which the fluid is injected, said measurement chamber 2 being delimited by a wall which internally defines a closed space;

a device 3 for injecting the fluid into the measurement chamber 2, the injection device 3 being supported by a first support 30 and comprising an injection conduit 31 which terminates in an injection orifice 32 located at the inside the measuring chamber 2;

a pressure sensor 4 disposed inside the measuring chamber 2 and supported by a second support 40;

a temperature sensor 5 disposed inside the measurement chamber 2 and supported by this second support 40;

a device 6 for emptying the measuring chamber 2, for fluidizing this measuring chamber 2, this emptying device 6 being supported by this second support 40 and comprising a draining duct 61 which starts with a drain orifice 62 located inside measuring chamber 2;

a control system 7 of the measurement, in particular of the electronic controller type.

The measurement chamber 2 has a generally ellipsoidal shape, in other words its wall is in the form of a non-spherical ellipsoid, and it has first and second foci F1, F2. In a particular embodiment, the measuring chamber 2 has a general shape of ellipsoid of revolution. This measuring chamber 2 has in its wall two so-called through holes, for example threaded holes, for the sealed passage of the supports 30, 40.

The injection device 3 comprises:

a regulating device 33, in particular of the actuator type, making it possible to regulate the flow rate and the pressure of the fluid entering via an inlet conduit 34 of the fluid;

- The inlet duct 34 at the input of the control device 33; and

the injection duct 31 at the outlet of the regulation device 33, which ends with the injection orifice 32.

The regulation device 33 is controlled either by the control system 7 (as visible in FIGS. 1 and 2 with the link 71), or by an external control system.

The emptying device 6 comprises: a regulating device 63, in particular of the actuator type, making it possible to regulate the flow rate and the pressure of the fluid leaving the drain conduit 61;

the emptying duct 61 at the inlet of the regulation device 63, which starts with the emptying orifice 62; and

an outlet duct 64 at the output of the regulation device 63.

The regulation device 63 is controlled either by the control system 7 (as visible in FIGS. 1 and 2 with the link 72), or by an external control system.

The first support 30 consists of a hollow tube which passes through the wall of the measuring chamber 2 in a sealed manner, and inside which the injection duct 31 is arranged in part. This first support 30 has a free end 35 positioned on the first focus F1 of the measuring chamber 2. The injection orifice 32 opens sealingly on this free end 35: this free end 35 is closed to prevent a return of fluid within the first hollow support. Thus, the injection port 32 is positioned on this first focus F1.

The second support 40 consists of a hollow tube which passes sealingly through the wall of the measuring chamber 2, and inside which the drain duct 61 is partly arranged. This second support 40 has a free end 45 positioned on the second focus F2 of the measuring chamber 2. The emptying orifice 62 opens sealingly on this free end 45: this free end 45 is closed to prevent a return of fluid inside the second hollow support 40. Thus, the emptying orifice 62 is positioned on this second focus F2. In addition, the pressure sensors 4 and temperature 5 are also mounted on this free end 45, so that these two sensors 4, 5 are also positioned on the second focus F2.

The sensors 4, 5 are connected to the control system 7, via respective links 74, 75, to ensure both the supply of the sensors 4, 5 and the transmission of the measurement data to the control system 7 .

The device 1 further comprises seals 37, 47 interposed between the supports 30, 40 and the wall of the measuring chamber 2, at the through holes for these supports 30, 40. These seals 37, 47 can be of the fluid seal type, made in particular by applying a fluid joint paste, in particular in the case where the through holes are threaded with the supports 30, 40 which are screwed into these through holes. In alternatively, these seals are of the solid seal type, that is to say made of a tight and flexible material.

As can be seen in FIGS. 1 to 3, the device 1 further comprises a screen 8 disposed inside the measuring chamber 2 and interposed between the two foci F1, F2, on the virtual line directly connecting the two foci F1, F2 between them. This screen has the function of eliminating the pressure waves from the first focus F1 and going directly to the second focus F2 without reflecting on the wall of the measurement chamber 2, to favor the waves that perform at least one first reflection on this wall.

This screen 8 may be made entirely or with a coating of material absorbing the pressure waves, and it is held suspended between the two foci F1, F2 with at least one link 80 fixed on the wall of the measuring chamber 2 and on the screen 8. This or these links 80 may be rigid link type, for example steel, or flexible link type, elastic or shock absorber. The screen 8 has limited dimensions so as not to disturb the pressure waves which carry out at least one reflection in the measuring chamber 2, with for example dimensions less than 40%, or even 30%, of the spacing between the two outbreaks F1, F2. In general, this screen 8 does not come into direct contact with the wall of the measuring chamber 2.

In the first and third embodiments of Figures 1 and 3, the measuring device 1 further comprises an outer enclosure 9 inside which is held suspended measurement chamber 2, without direct contact between the outer enclosure 9 and the measuring chamber 2, with several links 90 fixed on the measuring chamber 2 and on the outer enclosure 9.

The main purpose of this external enclosure 9 is to isolate the measurement chamber 2 from external influences and in particular shocks and vibrations. Thus, these links 90 are preferably flexible links, elastic or dampers, which are configured to damp the vibrations and shocks received by the outer enclosure 9 while preventing the measuring chamber 2 from bumping against the outer enclosure 9 .

In this first embodiment, the device 1 further comprises a regulation system 91 of the pressure inside the outer enclosure 9, which integrates: a regulating device 92, in particular of the actuator type, making it possible to regulate the fluid pressure in the outer enclosure 9 via a control duct 93 which opens inside the outer enclosure 9;

a fluid inlet duct 94 at the inlet of the regulation device 92; and a fluid outlet duct 95 at the outlet of the regulation device 92.

The control device 92 is controlled either by the control system 7 (as visible in FIGS. 1 and 2 with the link 73), or by an external control system.

This regulation system 91 further comprises a pressure sensor 96 and, optionally, a temperature sensor 97 disposed in the outer enclosure 9 and adapted to respectively measure the pressure and the temperature prevailing in this outer enclosure 9; these sensors 96, 97 being in connection with the control system 7, via respective links 76, 77, to ensure both the supply of the sensors 96, 97 and the transmission of measurement data to the control system 7 .

In this first embodiment, the supports 30, 40 also pass in a sealed manner to the external enclosure 9.

It is also conceivable to provide a safety valve (not shown) in the outer enclosure 9 and / or a safety valve (not shown) in the measuring chamber 2, to allow a safety discharge to the outside of the chamber. external enclosure 9 and / or measuring chamber 2 in case of overpressure.

As illustrated in Figure 3, it is also conceivable to provide one or more Helmholtz resonators 100 which opens on the wall of the measuring chamber 2, to attenuate the pressure waves; the use of such a Helmholtz resonator 100 being conceivable with or without the external enclosure 9.

The or each Helmholtz resonator 100 comprises a closed cavity 101 of volume V which communicates with the inside of the measuring chamber 2 via a tube 102 of length L and of section S, otherwise called the neck of the resonator. where the aforementioned dimensions are small in front of the wavelength of the pressure waves that it is desired to dampen.

Concerning the control system 7, the latter makes it possible to carry out the measurement and to control and control the measurement conditions, it is connected with the outside, such as for example an operator or a control system. or automation at a higher level. The control system 7 thus receives instructions, it optionally controls the regulating devices 33, 63, 92, receives the measurement data from the sensors 4, 5 and possibly 96, 97, and calculates measurement results (quantity of fluid injected) and supplies them externally.

Of course the implementation example mentioned above is not limiting and further improvements and details can be made to the measuring device according to the invention, without departing from the scope of the invention where other security features could for example be added to the device.

Claims

1. Device (1) for measuring a quantity of fluid injected by an injector comprising a measuring chamber (2) in which the fluid is injected, a device for injecting (3) the fluid into said measuring chamber (2), at least one pressure sensor (4) disposed in said measuring chamber (2) and adapted to measure the pressure in said measuring chamber (2), said device being characterized in that the measuring chamber (2) has a general ellipsoidal shape, in particular of the ellipsoidal type of revolution, having a first and a second focus (F1, F2), in that the injection device (3) comprises an injection orifice (32) positioned on the first focus ( F1) of said measuring chamber (2), and in that the pressure sensor (4) is positioned on the second focus (F2) of said measuring chamber (2).

2. Device (1) according to claim 1, further comprising a temperature sensor (5) disposed in the measuring chamber (2) and adapted to measure the temperature in said measuring chamber (2), and wherein said temperature sensor (5) is also positioned on the second focus (F2) of said measuring chamber (2), adjacent to the pressure sensor (4).

3. Device (1) according to claims 1 or 2, further comprising a draining device (6) of the measuring chamber (2) having a drain hole (62) also positioned on the second focus (F2) of said measuring chamber (2), adjacent to the pressure sensor (4).

4. Device (1) according to any one of claims 1 to 3, further comprising first and second hollow supports (30, 40) sealingly traversing said measuring chamber (2) and having free ends (35). , 45) respectively positioned on the first and second foci (F1, F2) of said measuring chamber (2) and respectively supporting the injection port (32) and the pressure sensor (4).

5. Device (1) according to claims 2, 3 and 4, wherein the second support (40) also supports at its free end (45) the temperature sensor (5) and / or the drain orifice (62). .

6. Device (1) according to claims 4 or 5, comprising seals (47, 57) interposed between the supports (30, 40) and the measuring chamber (2), preferably of the fluid seal type.

7. Device (1) according to any one of the preceding claims, further comprising a screen (8) disposed inside the measuring chamber (2) and interposed between the two foci (F1, F2), on the virtual line directly connecting the two homes (F1, F2) between them.

8. Device (1) according to claim 7, wherein the screen (8) is held suspended between the two homes (F1, F2) with one or more links

(80) fixed on the measuring chamber (2) and on the screen (8).

9. Device (1) according to any one of the preceding claims, further comprising an outer enclosure (9) inside which the measurement chamber (2) is held suspended, without direct contact between the external enclosure ( 9) and the measuring chamber (2), with one or more links (90) fixed on the measuring chamber (2) and on the outer enclosure (9), preferably flexible links, elastic or dampers.

10. Device (1) according to claim 9, further comprising a control system (91) of the pressure inside the outer enclosure (9).

1 1. Device (1) according to any one of the preceding claims, further comprising at least one Helmholtz resonator (100) which opens on a wall of the measuring chamber (2).

12. Device (1) according to any one of the preceding claims, wherein said device is a device for measuring a quantity of fuel injected by an injector used in a heat engine.