Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M65/00—Testing fuel-injection apparatus, e.g. testing injection timing ; Cleaning of fuel-injection apparatus
  • F02M65/001—Measuring fuel delivery of a fuel injector

Definitions

• the present invention relates to a device for instantaneously analyzing the injection rate blow by blow supplied by an injection system used in a heat engine.
• the injection systems concerned are also those found on vehicles equipped with a diesel engine, a petrol engine, an engine running on LPG (liquefied petroleum gas), or any other type of engine.
• Injection systems typically include one or more injection pumps responsible for putting fuel under pressure which can currently range from 100 to 2,500 bar, one or more pressurized fuel tanks, one or even several injectors per cylinder of the engine to be supplied and a control system, more and more often electronic, responsible for controlling the value of the masses or volumes of fuel injected as a function of the engine's environmental conditions, the characteristics of the fuel and the requirements of driving the engine .
• Measuring devices have been designed to allow manufacturers of injection systems and heat engines to carry out the development of the injectors as well as the adjustments and conformity checks during manufacture and during installation for end use.
• the known measuring devices are used in conjunction with a specific test bench whose role is essentially to ensure the rotation of an injection pump and the fixing of the various elements of the injection system under test. These devices cannot be used on an injection combustion engine in nominal operation.
• the measurements are Often do this by using a fluid other than the fuel for the injection of which the injection system is designed. This fluid is chosen to have hydraulic characteristics close to those of fuel but with a higher flash point temperature in order to minimize the risk of fire and explosion.
• the term fuel will also be used to designate the fluid used to carry out flow measurements.
• the measuring device includes a mechanical section as well as an electronic section.
• the mechanical section includes a fastening system for receiving one or more injectors, a measuring cell per injector for developing an electrical image of the quantity of fluid injected and a fluid evacuation system.
• the electronic section generally has the form of a box equipped with various means of interface with the operator such as a screen and a keyboard as well as other external processing systems.
• the electronic section processes an electrical signal supplied by the mechanical section, controls and controls various elements of service contributing to the measurement process.
• the basic technique used for the production of these measuring devices is based on the measurement of the displacement of a piston sliding in a jacket, the assembly delimiting a deformable measurement volume in which the injected fuel is directed. Any amount of fuel added to this volume causes displacement of the piston which can be easily converted into an electrical signal by the use of one of the many types of sensor available for this use. It is a volume measurement. Conversion to mass measurement is done by calculation using the value of the fuel density. To ensure an accurate calculation, the fuel temperature is measured in the measurement volume.
• the known measuring devices therefore make it possible either to know precisely the quantity of fuel injected by an injector or to know the shape of the flow curve as a function of time. There is not yet a measuring device making it possible to know both precisely the values of the volumes injected and the times / angles of injection.
• the present invention therefore aims to provide such a measuring device which therefore makes it possible to carry out these two different measurements at the same time.
• the device which it offers is a device for measuring a quantity of fuel injected by an injector used in a heat engine comprising a first measurement chamber into which the fuel is injected, a pressure sensor and a sensor. temperature measuring respectively the pressure and the temperature prevailing in the first measurement chamber as well as means making it possible to at least partially drain this measurement chamber, an electronic section controlling the system and analyzing information received by the sensors.
• this device comprises downstream of the first measurement chamber a second measurement chamber into which the fuel drained is sent out of the first measurement chamber, and the volume of the second measurement chamber is variable according to the displacement a piston whose displacement is measured using a displacement sensor.
• an injection is carried out.
• This causes an increase in pressure in the first measurement chamber, linked to the quantity of fluid injected, the characteristics of the fluid, the environmental conditions, in particular the temperature, the initial pressure and the volume of the chamber.
• the fluid that has been injected is discharged to the second measurement chamber.
• the pressure in the first measurement chamber is thus brought back to its initial value and this first chamber is ready to receive a second injection.
• the fluid which arrives in the second measurement chamber increases the volume of this chamber by pushing the piston. This displacement is measured and, knowing the diameter of the piston, part of the electronic section calculates the exact volume of fluid. This measurement allows the electronic section to calibrate, at all times, very exactly, the measurements that are made by the first measurement chamber.
• the first measurement chamber therefore makes it possible to supply the "shape" of the injection with precision, while the second allows the quantity of fuel injected to be measured.
• the processing carried out by the electronic section makes it possible to compensate for the defects of each of the measurements by the qualities of the other.
• the mechanical design of the device is more robust than the devices of the existing prior art. In particular, it is not necessary to use a pressure balancing device in the second measurement chamber. The back pressure is directly provided by the injection pressure in the first cell by playing on its emptying. The piston can then be simply returned by a spring.
• the constraints in the second measurement chamber being significantly less than in a chamber of the same type of the prior art, this chamber resists much better and wears out much less quickly.
• a rapid solenoid valve controlled by a part of the electronic section and a spillway are arranged between the two measurement chambers to partially empty the first measurement chamber after an injection until it finds in the first measurement chamber the pressure prevailing therein before this injection.
• the electronic section advantageously includes a compensation device making it possible to take into account any pressure difference in the first measurement chamber after two successive empties.
• a rapid drain solenoid valve is advantageously provided downstream of the second measurement chamber. .
• the piston can be prestressed for example by a spring towards the second measurement chamber.
• the piston moves in a cylinder with a smooth wall and has an annular groove open towards the wall of the cylinder.
• This groove makes it possible to trap any gas or fluid leaks while preventing these leaks from disturbing the measurement. It also makes it possible to lighten the piston. It also makes it possible to limit the surface area of the piston which must be run in and paired. Finally, it increases the flexibility of the piston, which makes it less difficult to slide it in the cylinder.
• the piston displacement sensor used is for example an inductive sensor, but any other type of sensor can be used here. It is also possible, for example, to use an optical sensor, of the interferometric type. Such a sensor is more precise, linear and does not add any moving mass to the mass of the piston. On the other hand, its cost is higher and its implementation more delicate.
• the measuring device can advantageously include a cooling system for cooling the injector, the first measuring chamber, the piston and the piston displacement sensor.
• a cooling system for cooling the injector, the first measuring chamber, the piston and the piston displacement sensor.
• the single figure very schematically shows the mechanical part of a device for measuring the quantity of fuel injected by an injector according to the invention.
• the single figure represents an injector 2 mounted on an injector support 4.
• This injector 2 comprises an injection nozzle 6 which is located in a first measurement chamber 8.
• This measurement chamber is a chamber of constant volume. It is filled with a fluid which has hydraulic characteristics close to those of a fuel but with a flash point temperature much higher than a fuel in order to minimize the risk of fire and explosion.
• This fluid is also the fluid which is used in the injector 2.
• a reservoir 10 of this fluid is provided in the device shown in the drawing.
• the first measurement chamber 8 has several inputs and several outputs. It firstly has a filling inlet 1 2, a purge outlet 14, a rapid drain outlet 1 6, and an outlet 18 to a second measurement chamber 20.
• fluid is pumped into the reservoir 10 using a pump 22 actuated by a motor 24.
• a fast filling solenoid valve 26 is mounted between the pump 22 and the inlet of filling 12 in order to control the filling of the first measurement chamber 8.
• a solenoid valve 28 is also provided at the outlet 14 for purging.
• a rapid emptying solenoid valve 30 is provided for the emptying of the chamber 8. It can be noted here that the rapid drain outlet 1 6 is advantageously placed at a low point of the first measurement chamber 8, while the purge outlet 14 is placed at a high point of this chamber 8.
• a drain solenoid valve 32 and an adjustable pressure relief valve 34 are disposed between the first measurement chamber 8 and the second measurement chamber 20.
• the second measurement chamber 20 has a variable volume. It is produced in a cylinder 36 in which a piston 38 moves.
• This piston 38 has a bottom 40 and a skirt 42.
• the bottom 42 is curved and forms a wall closing the measurement chamber 20.
• a spring 44 comes to bear on the bottom 40, on the side opposite to the measurement chamber 20. It is equally possible to have a piston with a convex, convex or concave bottom, as well as a piston with a flat bottom.
• the displacement of the measurement piston 38 is provided by a displacement sensor 46, engaged by a contact point 48 with the face of the bottom 40 opposite the measurement chamber 20.
• This displacement sensor 46 is for example an inductive sensor.
• the second measurement chamber 20 also includes a drain channel 50, the opening and closing of which are controlled by a drain solenoid valve 52 associated with an overflow valve 54.
• the drained fluid returns to the reservoir 10.
• the wall of the cylinder 36 along from which the piston 38 moves is a smooth wall. This cylinder may or may not be lined.
• the skirt 42 has on its outer face an annular groove 56. This groove extends over substantially half the height of the piston 38 and is centered relative to the height of the latter. Two annular guide surfaces 58 are thus produced.
• This mechanical device described above is associated with an electronic device not shown here and which receives information from two temperature sensors 60, each chamber being equipped with a quick response temperature sensor 60 as well as a pressure sensor. 62 located at the level of the first measurement chamber 8.
• a cooling system is also provided in the measuring device.
• the cooling fluid is the same as that which is injected at the level of the injector 2. Downstream of the pump 22, there is a heat exchanger 64. The same reservoir 10 therefore serves for the injected fluid and for the cooling.
• This cooling fluid is sent to the injector support 4 and then around the first measurement chamber 8, at the displacement sensor 46 and at the piston 38.
• An annular chamber 66 surrounds the displacement sensor 46 and comprises a cooling fluid supply channel and a channel for the return of this fluid to the reservoir 10.
• a groove 68 is provided in the injector support 4 to allow the circulation of the coolant around it. This groove 36 is supplied with coolant through a pipe and the coolant, after leaving the groove 36, passes into an annular chamber 70 situated around the first measurement chamber 8 before returning to the reservoir 10.
• the annular groove 56 of the piston 38 is also supplied with cooling fluid.
• a supply channel is provided for this purpose in the cylinder 36.
• Another channel is also provided for the return of the coolant to the reservoir 10. This return channel is advantageously offset in height with respect to the feed channel and is preferably located above the latter diametrically opposite to the latter.
• the first measurement chamber is firstly filled with fluid pumped into the reservoir 10 using the pump 22 and by opening the solenoid valve 26. Once the chamber is filled, it is purged using the solenoid valve 28 to ensure that no air bubbles or other gases are inside it. To fill the second measurement chamber, it is possible, during this filling, to open the solenoid valve 32 to the second measurement chamber 20.
• fluid is injected through the injector 2 into the first measurement chamber 8 until a pressure is obtained above the set pressure.
• the drain solenoid valve 32 and the overflow valve 34 the pressure in the first measurement chamber is reduced to the set pressure.
• the actual measurement can then begin.
• the injector 2 then injects fluid into the first measurement chamber 8. Thanks to the sensors, in particular the pressure sensor 62, it is thus possible to determine the curve of flow rate of injected fluid as a function of time. This injection in fact causes an increase in the pressure in the first measurement chamber. When the pressure in this chamber no longer increases, we deduce that the injection is finished.
• the solenoid valve 32 then opens and remains open until the pressure in the first measurement chamber substantially regains the initial set pressure.
• the overflow valve 34 makes it possible to maintain this residual set pressure in the first measurement chamber 8.
• the fluid which leaves the first measurement chamber 8 is sent to the second measurement chamber 20.
• the volume of this second measurement chamber 20 increases therefore, which causes a displacement of the piston 38.
• the displacement sensor 46 measures this displacement of the piston 38, and by knowing by means of the temperature sensor 60 the temperature of the fluid being in the chamber 20, it is possible to determine the quantity of fluid which has been introduced into the second measurement chamber 20.
• the main data are the initial pressure in the first measurement chamber, the final pressure in this chamber, and the pressure difference during injection, as well as the displacement of the piston 38.
• Using a method of so-called "crossed matrix" treatment we then obtain the results of the measurement. These results are obtained already before a second injection. Indeed, during the first injection the fluid is injected into the first measurement chamber. Then the fluid is transferred to the second measurement chamber 20. A second injection can then take place in the first measurement chamber 8. The results are obtained as soon as the transfer from the first measurement chamber 8, to the second measurement chamber 20 is finished, ie just before the second injection.
• the second measurement chamber is drained by means of the solenoid valve 52.
• the second overflow valve 54 makes it possible to maintain in the second measurement chamber 20 a second set pressure.
• the relationship between the increase in pressure and the volume injected is not linear. It depends in particular on the characteristics of the fluid, the temperature and the pressure. This pressure varies during the injection, and this phenomenon is used for the measurement.
• the calibration is carried out by injecting small volumes, but not too small in order to maintain a precision on the measurement, 10 mm 3 for example for a measurement scale of 200 mm 3 .
• Several injections are carried out successively, starting the injection at different pressures, chosen to cover the entire range of pressures encountered during nominal operation. Each injection is precisely measured by the second chamber 20. A series of correspondence points between a starting pressure in the chamber, a small variation in pressure due to the injection and the volume injected is obtained, at the nominal temperature of the measurements with the actual test fluid, in its current state.
• the calculation unit stores, periodically, a table of values making it possible to linearize and correct in real time the subsequent measurements.
• the advantage of this procedure is that it does not use any external device.
• the exploration of the different starting pressures is done simply by accumulating a few injections without opening the transfer solenoid valve to the second chamber which has the effect of gradually increasing the pressure in the first chamber 8 to the surroundings of each desired value to store a linearization curve.
• This calibration method is given by way of example and other methods can be envisaged here.
• This measuring device makes it possible to precisely obtain the quantity of fluid injected by the injector and also provides precisely the flow curve as a function of time.
• An electronic compensation device is provided to take account of a possible imperfection in the emptying phase of the first measurement chamber 8 and to provide precise measurement results even if the final pressure in this chamber, after emptying, is not not strictly equal to the nominal initial pressure.
• the system is capable of accounting for relatively large variations in this parameter. This compensation function is important because, among other factors, the response times for closing and opening the solenoid valve are not absolutely stable or predictable, even if their average value is taken into account by the system in the control sequence of this solenoid valve.
• the displacement of the piston measured by the displacement sensor 46 makes it possible, knowing the exact diameter of the piston, to calculate the volume injected. This measurement allows the electronic section to calibrate, at all times, very exactly the measurements that are made by the first cell.
• the groove 56 made in the piston provides several advantages. First of all, it traps any gas or fluid leaks, preventing them from disturbing the measurement. It also makes it possible to lighten the piston and therefore to limit the undesirable effects due to its mechanical inertia. Finally, it makes it possible to reduce the surface of the piston which must be perfectly run in and matched with the internal surface of the cylinder by limiting this guide surface to two rings located at the ends of the piston.
• the piston in particular at the level of its skirt, has a greater flexibility than that of the pistons used in the devices of the prior art thanks to the thinning of the skirt. All this is achieved without making it more difficult to produce the piston and, in addition, making it possible to reduce the stresses which hamper the sliding of the piston 38 in the cylinder 36.
• this system it is unnecessary to provide a counter pressure on the measuring piston using pressurized nitrogen. We This avoids any risk of leakage of this gas.
• the volume and mass of fuel injected at the injector 2 are measured at stabilized temperature. This brings reliability and precision to the measurement made.
• the processing carried out by the electronic section brings together the information obtained at the level of the two measurement chambers and makes it possible to compensate for the faults of each with the qualities of the other.
• the results provided to the operator or to external connected data processing systems are completely preprocessed by the electronic section and include all compensations.
• this measuring device is much more robust than in the systems of the prior art.
• it is no longer necessary to use the pressure balancing device in the first measurement chamber.
• This back pressure is provided directly by the injection pressure in this chamber by playing on its emptying.
• the second piston measurement chamber no longer needs to be particularly "rapid” since it is filled by the solenoid drain valve of the first measurement chamber, the operation of which is controlled. It no longer requires working with a back pressure and a simple spring is therefore sufficient to ensure its return.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Measuring Volume Flow (AREA)
• Fuel-Injection Apparatus (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
• Output Control And Ontrol Of Special Type Engine (AREA)
• Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)

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• 1999
  • 1999-06-18 FR FR9907982A patent/FR2795139B1/fr not_active Expired - Fee Related
• 2000
  • 2000-06-15 EP EP00949547A patent/EP1187987B1/de not_active Expired - Lifetime
  • 2000-06-15 ES ES00949547T patent/ES2237440T3/es not_active Expired - Lifetime
  • 2000-06-15 WO PCT/FR2000/001660 patent/WO2000079125A1/fr active IP Right Grant
  • 2000-06-15 DE DE60018928T patent/DE60018928T2/de not_active Expired - Lifetime
  • 2000-06-15 AT AT00949547T patent/ATE291694T1/de not_active IP Right Cessation
  • 2000-06-15 US US09/980,393 patent/US6755076B1/en not_active Expired - Lifetime
  • 2000-06-15 JP JP2001505451A patent/JP2003502578A/ja active Pending

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