FR2814203A1 - INJECTION DEVICE AND METHOD FOR IMPLEMENTING SUCH A DEVICE - Google Patents

Abstract

This injection device comprises a pump (2), serving to convey the fuel, a valve (6) which can be controlled, arranged after, downstream, of the pump (2) and serving to adjust the pressure. fuel, and a control or regulation unit (9) connected on the output side to the valve (6) and serving to control the valve (6) .The control or regulation unit (9) is connected to the input side to at least one sensor (11, 12, 13), in order to control the valve (6) as a function of a measured quantity (PMESS, n) reproducing the operating behavior of the injection device and / or of the engine to internal combustion.

Description

The invention relates to an injection device for a combustion engine.

  internal combustion engine, comprising a pump for conveying the fuel, a controllable valve arranged further downstream of the pump and for adjusting the fuel pressure, and a control or regulating unit connected on the output side to the valve and serving to control the valve. The invention also relates to a method of setting

  of such an injection device.

  Common rail injection devices comprise, for the accumulation of fuel under pressure, a pressure accumulator (in English: common rail, meaning common rail) from which the injectors associated with the different chambers engine combustion are fueled. The fuel is conveyed to the pressure accumulator by means of a high-pressure pump which is connected to the pressure accumulator via a controllable valve, the valve, which is disposed between the high pressure pump and the pressure accumulator, allowing adjustment of the fuel pressure prevailing in the pressure accumulator. Thus, the valve can for example derive a portion of the fuel flow discharged by the high pressure pump and return it to the low pressure zone of the injection device when the desired fuel pressure is reached or crossed upwards. By cons, in the case of a crossing down the desired pressure of fuel in the pressure accumulator, the valve disposed between the high pressure pump and the pressure accumulator can continue to send to the accumulator of pressure all the fuel flow discharged by the high pressure pump, so that the desired fuel pressure is reached again as quickly as possible in the pressure accumulator. Thus, the valve disposed between the high pressure pump and the pressure accumulator allows an adjustment of the fuel pressure prevailing in the pressure accumulator, in such a way that this valve is controlled by a control unit of a way corresponding to the fuel mass

to be injected.

  However, a disadvantage of these known injection devices lies in the fact that the fuel pressure in the pressure accumulator

  is not satisfactorily regulated.

  Therefore, the object of the invention is to improve the known injection device described above to such an extent that the pressure of fuel prevailing in the pressure accumulator coincides

  always as best as possible with the desired fuel pressure.

  For this purpose, the subject of the invention is an injection device, for an internal combustion engine, of the generic type defined in the introduction, characterized in that the control or regulation unit is connected on the input side to at least one sensor, in order to control the valve according to a measurement quantity reproducing the operating behavior

  of the injection device and / or the internal combustion engine.

  For the same purpose, the invention also relates to a method of implementing such an injection device, characterized in that it comprises the following operations consisting of detecting a measurement quantity reproducing the operating behavior of the device. internal combustion engine and / or the injection device, calculating the mass of fuel to be delivered by the pump, depending on the measurement quantity, and controlling the valve according to the mass of fuel to be

sent by means of the pump.

  The invention corresponds to the general technical teaching consisting in carrying out the control of the valve, arranged between the high-pressure pump and the pressure accumulator, as a function of a measurement quantity. Accordingly, the control or regulating unit for controlling the valve is connected on the input side to at least one sensor which detects a measurement quantity reproducing the behavior of the valve.

  operation of the engine and / or the injection device.

  Thus, for example, the control or regulation unit can be connected on the input side to a pressure sensor detecting the fuel pressure in the pressure accumulator, to a rotation speed sensor measuring the rotational speed. an engine shaft and / or a temperature sensor which measures the temperature of the fuel and / or the pressure accumulator. However, instead of the measurement variables indicated above, it is also possible to call upon

  other quantities of measurement to control the valve.

  The term control or regulation unit must be understood in a general manner within the scope of the invention and encompasses commands without feedback, as well as regulations in which the output signal

  is subject to feedback for regulatory purposes.

  However, in the preferred embodiment of the invention, the control or regulation unit comprises two regulators with different dynamic behavior -3 different. This offers the advantage that the control and regulating unit can react on the one hand in a precise way and

  on the other hand in a fast way to modified boundary conditions.

  The injection device according to the invention may also have one or more of the following features: the control or regulating unit is connected on the input side to a pressure sensor which measures the fuel pressure in a pressure accumulator disposed downstream of the pump, the control and control unit is connected on the input side to a rotational speed sensor which measures the rotational speed of a shaft of the internal combustion engine; The control or regulating unit is connected on the input side to a temperature sensor which measures the fuel temperature; the control or regulation unit comprises two regulators having different dynamic control behaviors, in order to be able to react on the one hand in a precise manner and on the other hand in a fast manner to modified boundary conditions, when controlling the valve, - the regulator presenting the dynamometer The largest control unit comprises a calculation unit which calculates the target fuel mass in the pressure accumulator from a predetermined set fuel pressure and the temperature measured by the temperature sensor. having the highest control dynamics has a calculation unit which is connected on the input side to the rotational speed sensor and calculates the target fuel pressure from the measured rotational speed and the injected fuel mass; the regulator having the greatest regulation dynamics comprises a calculation unit which calculates the theoretical mass of fuel in the pressure accumulator from the prefixed fuel mass and the mass of fuel delivered by the pump; regulator having the greatest regulation dynamics comprises a comparison unit or a subtractor that compares the mass a reference fuel to the calculated theoretical fuel mass, - the regulator having the highest control dynamics has a dead time element to account for the idle time of the valve, the regulator having the weakest control dynamic has a calculation unit which is connected on the input side to the temperature sensor and the pressure sensor and calculates the mass of fuel in the pressure accumulator from the measured fuel pressure and the temperature measured, - the regulator having the lowest regulation dynamics comprises a comparison unit or a subtractor that compares the fuel mass in the pressure accumulator, calculated from the

  measurement values, to the theoretical fuel mass.

  The method of implementation according to the invention may also have one or more of the following features: the mass of fuel to be discharged by the pump is regulated, the mass of fuel to be discharged by the pump is regulated by means of two regulators having different dynamic control behaviors, - the mass of fuel to be discharged by the pump is regulated according to the speed of rotation, of the fuel temperature, the injected fuel mass and / or the fuel pressure, - the fuel pressure in the pressure accumulator is measured, the fuel mass to be discharged by the pump being determined as a function of the deviation of the measured fuel pressure from a predetermined set fuel pressure; - the fuel temperature is measured and the fuel mass to be measured; efoulée by the pump is determined according to the

  measured fuel temperature and measured fuel pressure.

  Other advantageous developments of the invention will emerge from the

  description of its preferred embodiment which is made hereinafter in

  look at the drawings. FIG. 1 shows an injection device according to the invention, in FIG. 2, in the form of a block diagram, the unit for controlling or regulating the injection device represented in FIG. 1 and, in FIGS. 3a and 3b, in the form of a flow chart, the method of setting

  implementation of the injection device shown in Figure 1.

  The injection device shown in FIG. 1 as a preferred embodiment of the invention comprises, for conveying the fuel from a fuel tank 1, a low pressure pump 2 which is driven by a shaft 3 of the internal combustion engine. However, as an alternative to this type of drive, the low pressure pump 2 can

  also be driven by a separate electric motor.

  On the output side, the low pressure pump is connected to a low pressure regulator 4 which, when a prefixed fuel pressure is, in the low pressure zone of the injection device, crossed upwards or beyond, derives part of the fuel flow discharged by the low pressure pump 2 and returns to the fuel tank 1. On the other hand, when the predetermined fuel pressure is, in the low-pressure zone of the injection device, crossed down, the regulator low pressure 4 causes a blockage, so that no part of the fuel from the low pressure zone is returned to the fuel tank 1, which should cause a rapid rise in fuel pressure in this low-pressure zone pressure of the injection device. On the downstream side, the low pressure pump 2 is connected to a high pressure pump 5 which produces the injection pressure necessary for the injection of the fuel into the combustion chambers of the engine and is connected on the output side to a pressure accumulator 8 (in English: common rail, meaning common rail) by means of a bypass valve 6 and a check valve 7. All the injectors of the engine are supplied with fuel from the accumulator 8, the connections of input to injectors not being

  represented here only schematically.

  The non-return valve 7 serves to prevent fuel reflux from the pressure accumulator 8 towards the bypass valve 6. Contrary to this, the bypass valve 6 serves to control the fuel pressure prevailing in the pressure accumulator 8. If the fuel pressure prevailing in the accumulator 8 passes, for example, down the desired fuel pressure, the bypass valve 6 directs the entire fuel flow, discharged by the high pressure pump 5 , in the pressure accumulator 8 by passing through the check valve 7, so that the fuel pressure in the accumulator 8 increases relatively quickly. On the other hand, if the fuel pressure prevailing in the accumulator 8 passes upwards or exceeds the desired fuel pressure, the bypass valve 6 completely or partially directs the flow of fuel, delivered by the high-pressure pump 5, into the low-pressure zone of the injection device, so that the fuel pressure in

  the battery 8 decreases again quickly.

  The control of the bypass valve 6 is effected by means of a control or regulation unit 9 which is connected on the input side to the electronic engine control ECU (of the "electronic control unit", meaning the control unit electronics), the electronic engine control for example the injectors of the injection device, this

  which is shown only schematically in the drawings.

  In addition, the control or control unit 9 is connected to a pressure sensor 1 1 which detects the pressure of fuel PMESS prevailing

in the pressure accumulator 8.

  Furthermore, the control or control unit 9 is connected to a rotational speed sensor 12 which measures the speed of rotation of the shaft.

of motor 3.

  Finally, there is further provided a temperature sensor 13 which measures the temperature TF of the fuel in the pressure accumulator 8 and transmits

  the measured value at the control or control unit 9.

  The method of implementation of the control unit 9 is explained below, with reference to the detailed representation of the control or control unit 9 which is shown in FIG. 2, as well as to the flowchart

shown in Figures 3a and 3b.

  Essentially, the control or control unit 9 consists of two regulators 14, 15, the regulator 15 having a dynamic behavior or a dynamic regulation which is slow and has to regulate as accurately as possible the pressure of fuel in the accumulator 8, while the regulator 14 serves as a pilot control and therefore has a dynamic behavior or dynamic control that is fast, in order to be able to adjust as quickly as possible the amount repressed to boundary conditions

changed.

  The regulation process of the regulator 15 is essentially presented in FIG. 3a, while the regulation process of the regulator

  14 is essentially in Figure 3b.

  We will first describe below the regulatory behavior of the

regulator 14.

  On the input side, the regulator 14 comprises two calculation units 16, 17 which receive from the rotational speed sensor 12 the rotation speed n and -7- of the electronic engine control 10 the injected fuel mass mINJ and calculates the value PSOLL1 or PSOLL2 set point of the fuel pressure according to these two measured values, the two setpoints PSOLL1 and PSOLL2 corresponding to different types of engine operation. Therefore, in order to select the desired setpoint corresponding to the current operating mode of the motor, a controllable switching element 18 is arranged which is arranged after the two calculation units 16, 17. and which selects the output signal of one of these two calculation units 16, 17, the switching element 18 being controlled by the motor electronic control

  via an ECU2 command line.

  On the output side, the switching element 18 is connected to another switching element 19 which optionally selects the calculated setpoint value PSOLL1 or PSOLL2 or a setpoint value PSOLL, prefixed TEST serving for test purposes, the control of the switching element 19 being effected by means of the motor electronic control 10 via a control line ECU1. It is therefore the desired set point value for the fuel pressure prevailing in the pressure accumulator 8 which

  appears at the output of the switching element.

  This PSOLL setpoint value is then sent to a calculation unit 20 which is connected on the input side to the temperature sensor 13 and calculates, according to the PSOLL set point of the fuel pressure and the fuel temperature TF, the msoLL setpoint of the mass of fuel that should be in the pressure accumulator. This mSOLL setpoint value is then sent to a subtractor 21 which subtracts from this msOLL setpoint value a theoretical calculated real value mCALC. The difference obtained in this way is then sent to an adder 22 which adds to it the mass of fuel to be injected mlNJ, so that the difference Am between the msoLL setpoint of the mass of the mass appears at the output of the adder 22. fuel and the calculated actual theoretical value mCALC of the fuel mass addition made the

fuel mass injected mINJ.

  The regulator 14 further comprises a calculation unit 23 which, from the value Am, of the mass of fuel to be injected mINJ and the mass of fuel mpUMP delivered by the high pressure pump 5 to the pressure accumulator 8, calculates the theoretical true value mCALc of the mass of fuel in the accumulator 8. This theoretical calculated value is then further sent to a correction unit 24 to take account of the ECU sampling. The mCALc signal is then again sent to another correction element 25 which takes into account the dead time of the bypass valve 6. This is the theoretical calculated mass mCALc found in the accumulator 8 which appears at the output of the correction element 25. The following is now described the control behavior of the

  regulator 15, with particular reference to the flowchart of FIG. 3b.

  The regulator 15 comprises on the input side a calculation unit 26 which, based on the temperature TF of the fuel and the fuel pressure PMESS measured by the pressure sensor 11, calculates the mass of fuel mMESS which is in the accumulator of This measurement value mMESs is then sent to a subtracter 27 which calculates the difference between the calculated theoretical mass value mCALC and the mass value.

mMESs resulting from the measurement.

  On the output side, the subtractor 27 is connected to an average value forming element 28 (MV) which, from the difference calculated by means of the subtractor 27, calculates the moving average value over the range of a time step. of the motor. The signal subjected to the average value formation is then sent by a proportional-integral regulator 29 (PI) which defines the control behavior and provides on the output side a control variable which is joined in an adder 30 to the magnitude calculated by the regulator 14, so that it is the mass of fuel mpuMP to be repressed by the

  high pressure pump 5 which appears at the outlet of the adder 30.

  On the output side, the adder 30 is connected to a converter 31 which conveniently controls the bypass valve 6 as a function of

  the mpuMp fuel mass applied on the input side.

  The invention is not limited to the preferred embodiment described above. On the contrary, it is possible to imagine a number of variations and modifications that use the concept according to

  The invention and thus also enter the protection framework.

  BACKGROUND 1. Injection device for an internal combustion engine, comprising: a pump (2) for the conveyance of fuel, a valve (6) which can be controlled, arranged subsequently, downstream of the engine, pump (2) and for controlling the fuel pressure, and a control or regulating unit (9) connected on the output side to the valve (6) and for controlling the valve (6), characterized in that the the control or regulating unit (9) is connected on the input side to at least one sensor (i 1, i 2, i 3), in order to control the valve (6) as a function of a measurement quantity (PMESS, n) reproducing the operating behavior of the injection device

  and / or internal combustion engine.

  Injection device according to Claim 1, characterized in that the control or regulating unit (9) is connected on the inlet side to a pressure sensor (11) which measures the fuel pressure in a

  pressure accumulator (8) disposed subsequently downstream of the pump (2).

  3. Injection device according to any one of claims i

  and 2, characterized in that the control and regulating unit (9) is connected on the input side to a rotational speed sensor (12) which measures the

  speed of rotation of a shaft (3) of the internal combustion engine.

  4. Injection device according to any one of claims i

  at 3, characterized in that the control or regulating unit (9) is connected on the input side to a temperature sensor (13) which measures the

fuel temperature.

  5. Injection device according to any one of claims i

  to 4, characterized in that the control or regulating unit (9) comprises two regulators (14, 15) having different control dynamics, in order to react on the one hand in a precise manner and on the other hand part of a fast way to boundary conditions

  modified, when controlling the valve (6).

  Injection device according to claims 4 and 5, characterized

  in that the regulator (14) having the highest control dynamics comprises a calculation unit (20) which calculates the target fuel mass (msOLL) in the pressure accumulator (8) from a pressure setpoint fuel (PsoLL) and temperature (TF)

  measured by the temperature sensor (13).

  Injection device according to claims 3 and 6, characterized

  in that the regulator (14) exhibiting the highest dynamics ie regulation comprises a calculation unit (16, i7) which is connected on the input side to the speed sensor (12) and calculates the target fuel pressure ( PsoLL) from the rotational speed (n) measured and the

  injected fuel mass (mINJ).

  8. Injection device according to claim 7, characterized in that the regulator (14) having the largest control dynamics comprises a calculation unit (23) which calculates the theoretical mass of fuel (mCALC) in pressure accumulator (8) from prefixed fuel mass (mINJ) and fuel mass (mpuMp)

pumped back.

  9. Injection device according to claim 8, characterized in that the regulator (i4) having the greatest control dynamics comprises a comparison unit or a subtractor (21) which compares the target fuel mass (msOLL). to the theoretical fuel mass

(mCALC) calculated.

  10. Injection device according to any one of the claims

  6 to 9, characterized in that the regulator (14) having the largest control dynamic has a dead time element (25) in order to

  take into account the dead time of the valve (6).

  ii. Injection device according to claims 2, 4 and 5 catches

  together, characterized in that the regulator (15) having the lowest regulation dynamics comprises a calculation unit (26) which is connected on the input side to the temperature sensor (13) and to the pressure sensor (1i) and calculates the mass of fuel (mMEss) in the pressure accumulator (8) from the measured fuel pressure (PMESS) and the

measured temperature (TF).

  Injection device according to Claim 11, characterized in that the regulator (15) exhibiting the weakest control dynamics comprises a comparison unit or a subtracter (27) which compares the fuel mass (mMEss) in i pressure accumulator (8), calculated at

  from measurement values to the theoretical fuel mass (mCALC).

  13. Method of implementing an injection device according to one

  any of claims i to i2, characterized in that it comprises the

following operations consisting of:

- 11 -

  - detecting a measurement quantity reproducing the operating behavior of the internal combustion engine and / or the injection device, - calculating the mass of fuel to be sent by the pump (2), depending on the measurement quantity , and - to control the valve (6) according to the mass of fuel

  to be sent by means of the pump (2).

  14. A method according to claim 13, characterized in that the mass of fuel to be discharged by the pump (2) is regulated. Method according to Claim 14, characterized in that the mass of fuel to be discharged by the pump (2) is regulated by means of two regulators (14, 15) having

  different regulatory dynamics.

  16. Process according to any one of claims 14 and 15,

  characterized in that the mass of fuel to be discharged by the pump (2) is regulated as a function of the rotational speed, the fuel temperature, the injected fuel mass and / or the

fuel pressure.

  17. The process of any one of claims 13 to 16,

  characterized in that the fuel pressure in the pressure accumulator (8) is measured, the mass of fuel to be discharged by the pump (2) being determined according to the difference of the fuel pressure

  measured with respect to a predetermined set fuel pressure.

  18. A process according to any one of claims 13 to 17,

  characterized in that the temperature of the fuel is measured and the mass of fuel to be discharged by the pump (2) is determined as a function of the measured temperature of the fuel and the pressure of the fuel.

measured fuel.