FR2767561A1 - METHOD AND DEVICE FOR CONTROLLING AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

Method and device for controlling an internal combustion engine characterized in that the regulating system is made linear and the regulating apparatus predefines a quantity which corresponds to the fuel flow which is necessary for the pressurization and / or the drop pressure.

Description

State of the art The invention relates to a method and a device

  for controlling an internal combustion engine, in particular an internal combustion engine with a common rail system, method in which a preset value is predefined by

  pressure in a pressure accumulator and it is understood

  against a real value, so that, starting from this comparison, an adjustment device predefines a

  quantity used to form a control signal for an or-

adjustment gane.

  Document DE 195 482 78 discloses a method and a device for controlling an internal combustion engine. In this document, a method and a device for regulating the pressure in a system are described.

  common rail which is used in the case of a combustion engine

  internal tion. In the case of this system, the large-

  adjustment date for the pressure adjustment valve

  directly by means of a usual adjustment device

  portable-integral PI. As the adjustment system is form-

  non-linear, the design of the adjustment device

is complicated.

  OBJECT OF THE INVENTION The object of the invention is to provide a simple adjustment structure in the case of a device and a method used to control an internal combustion engine. This problem is solved by the fact that the adjustment system is made linear and the adjustment device predefines a quantity which corresponds to the fuel flow rate which is necessary for setting

  pressure and / or pressure drop.

Advantages of the invention

  We simplify the design of the parameters of

  adjustment by making the adjustment system linear.

  According to other characteristics of the invention:

  - the adjustment device predefines a setting flow

if we.

  - you can predefine an adjustment variable to supply

  an adjuster according to the size which corresponds

  pond to the fuel flow required to pressurize

and or when the pressure drops.

  - the variable of adjustment can be predefined according to other quantities such as a delivery flow, a dosing flow and / or the pressure. - the dosing flow can be predefined starting from the flow

  of fuel to be injected into the internal combustion engine

  dull. - the delivery rate can be preset at least in

starting from the speed of rotation.

  - the pressurization flow can be predefined by starting

an adjustment deviation.

  the adjustment system is made linear and the adjustment device predefines a quantity which corresponds to the fuel flow which is necessary for pressurization and / or

pressure drop.

Drawings

  The invention will be described below in more detail.

  tail from several embodiments shown in the accompanying drawings in which:

  - Figure 1 shows a block diagram of the device se-

  lon the invention, - Figure 2 shows a schematic representation of the pressure adjustment valve, - Figure 3 shows a characteristic field and, - Figure 4 shows a block diagram of the structure

adjustment.

  Description of the exemplary embodiments

  FIG. 1 shows the parts cons-

  necessary for understanding the invention, a fuel supply system for a combustion engine

  internal with high pressure injection. The system represents

  This is usually referred to as a common rail system. We have designated by the reference 100 a reservoir of

  fuel. This is linked by means of a first wire-

  tre 105 and a transfer pump 110 with a second filtration means 115. From the second filtration means 115 the fuel arrives via a pipe to a valve 120. The connection pipe which is located between the filtration means 115 and the valve 120 is connected by means of a low pressure limiting valve 145 with the tank 100. The valve 120 is connected by means of a

  high pressure pump 125 with a rail 130. The rail is also

  if designated as a pressure accumulator and is in contact via fuel lines with different injectors 131. By means of a pressure adjustment valve 135, it is possible to connect the rail 130 with the fuel tank 110 The pressure adjustment valve 135 can

  be controlled by means of a coil 136.

  The pipes between the outlet of the high pump

  125 pressure and the inlet of the pressure adjustment valve

  sion 135 are designated as the high pressure area. In this area, the fuel is under high pressure. The pressure in the high pressure zone is detected by means of a sensor 140. The lines between the tank 100 and the high pressure pump 125 are designated as the zone to

low pressure.

  The system works as follows. The fuel which is in the tank is transferred by the prior delivery pump 110 through the filtration means 105 and 115. On the outlet side of the prior delivery pump 110 the fuel is supplied under a pressure which is between 1 and 3 bars approximately. When the pressure in the low pressure zone of the fuel system has reached a value which can be defined beforehand, the valve 120 opens and the inlet of the high pressure pump

  125 is supplied with a determined pressure. This pres-

  sion depends on the realization of the valve 120. Usual-

  the valve 120 has a configuration such that it releases the connection with the high pressure pump 125 at a pressure

about 1 bar.

  If pressure rises in the low pressure area

  at unacceptable high values, the limit valve

  The low-pressure valve 145 then opens and releases the connection between the outlet of the prior delivery pump 110 and the tank 100. By means of the valve 120 and the low-pressure limiting valve 145, the pressure is maintained in

  the low pressure zone at values between approx.

ron 1 and 3 bars.

  The high pressure pump 125 transfers the fuel

  rant from the low pressure area to the high pressure area

  if we. The high pressure pump 125 establishes in the rail 130 a very high pressure. Usually we get in

  systems for internal combustion engine with ignition

  external similar pressure values ranging from around

  bars up to 100 bars and in the case of combustion engines

  tion with controlled ignition, pressure values ranging from around 1000 bars up to 2000 bars. Via the injectors 131 the fuel can be brought in metered manner under a high

  pressure at the different cylinders of the internal combustion engine

  dull. By means of the sensor 140, the pressure in the rail or in the entire high pressure zone is detected. Thanks to

  of the pressure control valve 135, which can be com-

  mandated by a coil 136, the pressure can be adjusted in the high pressure zone. Depending on the voltage applied to the coil 136 or the current passing through the coil

  136, the pressure adjustment valve 135 opens at different times.

pressure values.

  As a back-up pump, electric fuel pumps are usually used with a direct current motor (DC motor) or a current motor.

  continuous with collector (EC motor). For delivery rates-

  which are particularly necessary in the

  In the case of utility motor vehicles, one can also use

  ser several pre-discharge pumps mounted in parallel

  rally. In this case, collector motors (EC motor) are preferably used because of their longer service life.

  and their greater availability.

  To set the pressure P in the high zone

  pressure, other regulating members can also be used.

  These are for example an electric pre-delivery pump.

  alable 110 whose flow can be adjusted or a high pump

  pressure 125 which can be controlled. In addition, one can pre-

  see also for the pressure adjustment valve 135, a pressure limiting valve which for a predefined pressure value releases the connection between the high pressure zone and the low pressure zone.

  In what follows, Q designates the flow rates or the variations in quantities. These are the quantities of fluid that flow during a specified time interval. From the high pressure pump 125, the delivery flow QP in the rail 130 is transferred in a determined time interval. The control flow QDRV is discharged into the low pressure zone via the pressure control valve. pressure 135. The setting flow

  QR pressure is available for pressurization. Of the-

  dosing bit IQ arrives at injectors 131 via injections

  131. The QI flow rate consists of the quantity of fuel injected QK, the leakage flow rate and an injection control flow rate. The leak rate and the

  control return to the low pressure area again.

  The injected flow arrives in the combustion chambers of the

internal combustion engine.

  In FIG. 2, the pressure relief valve is shown.

  pressure setting and the rail 130 schematically

  than. The pressure in the rail is designated by the letter P, by I the intensity in the coil of the valve for adjusting the

  pressure and by X the position of the armature.

  A ball 200 is pressed by a frame 210 on the seat of the valve. The coil 220 which is traversed by the intensity I, exerts a force on the armature. In addition, a spring 230 is provided, which presses the ball 200 into the valve seat. The force exerted on the armature and in this way on the ball, with which it is pressed in

  the valve seat is determined by the different sizes

  deurs. On the one hand, it is the magnetic force FM which is a function of the intensity I, which passes through the coil and of the position X of the armature. A pressure force FP acts

  against these forces, pressure force FP which can be represented

  felt as a function F of the pressure P in the rail 130 and of the position X of the armature or as a function F of the

  QDRV setting flow and armature X position.

  In the stationary state, the force which

  this results in two quantities. The other quantities are re-

  frozen accordingly. By the force exerted on the armature we have: The force of the armature can be represented as a function of the intensity I and of the position X of the armature as the force FAl. In addition, the armature force can be represented as the force FA2 as a function of the pressure P and the position X of the armature. Also, we can represent

  this armature force as the FA3 force as a function of the

  QDRV setting bit and armature X position.

  These forces are shown on line 3 as characteristic curves. The force FA1 has been plotted as a family of characteristic curve curves with solid lines giving the intensity I as a function of the position X of the armature. The force FA2 has been represented by dashed lines giving as a family of parameters with the parameter of the pressure P. The force of the armature FA3 has been brought as family of parameters in the form of a family of dashed curves with the flow parameter

QDRV setting.

  In the stationary state we have the following relation:

QDRV = QP - IQ

  In the non-stationary case, that is to say during the pressurization or during the fall of the pressure one has the following relation:

QDRV = QP - IQ - QR

  The QR pressurization flow leads to the

pressure in the rail.

  The time ends of the magnetic circuit and the armature are so small that we have permanently

  FAl = FA2 = FA3. By means of the family of characteristic curves

  The figures shown in Figure 3 can be used to determine the QR pressurization flow. The force of the armature FA and the position X of the armature are unequivocally determined by the pressure in the rail P and the intensity I in the coil which actuates the armature. In this way, we have the characteristic curve FA3 and in this way the QDRV bit rate. We have the following relation:

QR = QP - QI - QDRV

  the adjustment flow QDRV is a function of the pressure P and of the intensity I. The pressurization flow QR is a function of the difference between the delivery flow and the metering flow QP - QI of the pressure P and of intensity I. This function represents the non-linear operating mode of the adjustment system according to the invention,

  upstream of this function a characteristic field in three di-

  mensions so that mounting one behind the other

produce a linear relation.

  A corresponding adjustment structure is shown.

  laying down in Figure 4 and designated by the reference 400

  the pressure regulator itself. The one-

  ci delivers a QR adjustment variable to a character field

  tick 410. The characteristic field actuates the adjustment system 436 with a signal I. This means that the coil 136

  is dependent on the adjustment difference between the value of

  sign PS and the actual value P with an intensity I. As another input quantity, the output signal P from the pressure sensor 140 as well as the output signal from a combination point 415 arrive at the characteristic field. On the first input from the point of combination 415 is the quantity QP and on the second entry is with a negative sign the quantity QI. The quantity QP is provided by a prior definition QP 420 and the quantity

  IQ by the prior definition QI 430.

  The adjustment deviation which is formed by the combination point 440 is brought to the adjustment device 400 as an input signal. On an input of the combination point 440 there is with a negative sign the effective value P of the

  press, on the second entry is with a po- sign

  the PS setpoint value of a preset value

  setpoint 450. The characteristic field supplies the pressure adjustment valve with an intensity I.

  This device then operates as follows:

  boasts. The predefined QP calculates from the rotational speed N and a constant KI the discharge flow QP

  which corresponds to the discharge power of the se-

according to the formula:

QP = K1 * N

  The preset QI 430 calculates the data rate

  wise IQ from the fuel flow to inject QK, from

  injector control flow more than one leakage flow se-

according to the formula

IQ = QK + A + QK

  In this case, it is assumed that the sum of the control flow and the leakage flow constitutes a fixed percentage A of the fuel flow QK to be injected. To calculate the dosing flow QI, we increase by a determined percentage A

  the injection rate QK, percentage A which corresponds to the

  control bit and leak rate. The characteristic field 410 is supplied with the difference of these two signals QP and QI. In addition, the characteristic field is supplied with the pressure signal P.

  The pressure setting device 400 preset

  nit as a function of the adjustment difference between the con-

  sign PS and the actual value P a quantity, which corresponds to the fuel flow necessary for pressurization and / or pressure drop. This quantity is designated as

  being the flow QR1 which is necessary for the pressurization.

  In the characteristic field 410, the intensity I is deposited as a function of the current pressure P. of the discharge flow QP and of the dosing flow QI, intensity I which is necessary to supply in the case of the operating parameters given the flow QRI desired for pressurizing the adjusting device. In this case, the characteristic field retains the function fL according to the following equation: I = fL (QR1, QP-QI, P) With the corresponding intensity I, the adjustment system 436 is supplied. Depending on the intensity I which flows through the sum 136 of the valve for adjusting the

  pressure, pressure P in the rail and discharge flow

  Likewise QP, and the dosing flow QI, we establish according to the

  following function the effective flow QR2.

Q R2 = fS (QP - QI, I,

  The functional relationship fS of the quantities above

  above is non-linear. If we put the function fL in

  upstream of this function, we thus have QR1 equal to QR2. We elect

  in this way undermines the non-reality of the system.

  The pressurization flow QR is then used as an adjustment variable for the pressure adjustment circuit. The adjustment system is made linear by the characteristic field 410. With the pressurization flow

  QR as an adjustment variable, we obtain a

  linear alignment; it is above all a device

  integration. When pressurized, the quantity con-

  titrated by the pressurizing flow QR takes negative values.

R E V E N D I C AT I ON S

  1) Method for controlling an internal combustion engine, in particular an internal combustion engine with a common rail system, method in which a preset value is predefined by a pressure in a pressure accumulator and

  we compare it to a real value, so that

  both from this comparison an adjustment device predefines a quantity used to form a control signal for an adjustment member, characterized in that

  the adjustment system is made linear and the adjustment device

  glage predefines a quantity which corresponds to the flow of

  burant which is necessary for pressurization and / or

pressure drop.

  2) Method according to claim 1, characterized in that the adjustment device predefines a pressurizing flow (QR).

  3) Method according to one of the preceding claims,

  characterized in that a control variable can be predefined to supply

  an adjuster according to the size which corresponds

  pond to the fuel flow required to pressurize

and or when the pressure drops.

  4) Method according to one of the preceding claims,

  characterized in that the control variable can be predefined as a function of other quantities such as a delivery rate (QR), a

  dosing flow (QI) and / or pressure (P).

   ) Method according to claim 4, characterized in that the dosing flow (QI) can be predefined starting from

  fuel flow (QK) to be injected into the combustion engine

internal tion.

  6) Method according to claim 4, characterized in that the delivery rate (QP) can be predefined at least in

  starting from the speed of rotation (N).

  7) Method according to one of the preceding claims,

  characterized in that the pressurizing flow can be predefined starting from

an adjustment deviation.

  8) Device for controlling an internal combustion engine

  dull, in particular an internal combustion engine with a common rail system, device in which a preset value for a pressure in a pressure accumulator is predefined and compared with an actual value of such

  so that starting from this comparison a re-

  setting predefines a quantity used to form a control signal for an adjusting member, characterized in that

  the adjustment system is made linear and the adjustment device

  glage predefines a quantity which corresponds to the flow of

  burant which is necessary for pressurization and / or

pressure drop.