FR2667651A1 - CONTROL SYSTEM FOR A SELF-IGNITION INTERNAL COMBUSTION ENGINE. - Google Patents

Abstract

a) Control system for a self-igniting internal combustion engine. b) The invention is characterized in that a set point value (RW) for the second control device (130) is corrected as a function of a signal indicating the start of injection and a signal indicating the quantity of injected fuel (QK). c) The invention applies to injection pumps of self-igniting vehicle engines.

Description

Control system for a combustion engine

internal self-ignition ".

  The invention relates to a control system for a self-igniting internal combustion engine, with a first control device, which determines the beginning of the fuel injection, and a second device which determines the quantity of fuel to be injected, a set value for the first control device being delivered according to different operating parameters at least to a characteristic field Such a control system is known from the German patent application

  put in the public inspection 3,522,414 (USA 4,619,233).

  In this document, there is described a control system for an internal combustion engine, in which the instant of the fuel injection is determined by a first control unit and the quantity of fuel to be injected by a second control unit. With regard to the first control unit, this is called a reciprocating spool. In this system, a movement of the first control unit also acts on the amount of fuel. control signal for the second control unit, which determines the quantity of fuel to be injected, is corrected by a correction factor This correction factor depends on the speed of rotation and the actual position of the first unit

  control (of the reciprocating drawer).

  Such a correction, by means of a factor depending only on the speed of rotation and the actual position of the drawer, is not sufficient to

  a precise adjustment of the quantity to be injected.

  In the device described above, there are inaccuracies with regard to the amount of fuel When a fine adjustment of the control unit influencing the amount of fuel to be injected, there is a quantity of fuel

  variable depending on the drawer setting.

  It is desirable to be able to adjust in a completely independent way the two sizes: the beginning of the injection and the amount of fuel It turned out that it was not possible to have a sufficient correction with a correction factor that only takes into account the speed of rotation and the position of the drawer. By means of a system according to the state of the art, the quantity of fuel to be injected can not be regulated completely independently of the beginning of the injection. It follows inaccuracies.

  in the amount of fuel to be injected.

  The object of the invention is to improve a control system of the type mentioned at the beginning, so as to obtain a fuel dosage as exact as possible, and is characterized in that a set value for the second control device is corrected according to a signal indicating the start of the injection and a signal

  indicating the amount of fuel.

  Our device guarantees a constant injection quantity for a predetermined fixed set value of the quantity to be injected for each speed of rotation and each position of the drawer that we want We obtain taking into consideration all the factors that influence the quantity of fuel by means of a multidimensional pump characteristic field The characteristic field is used to correct the nominal value of the normal path depending on the position of the spool, the speed of rotation and the position of the spindle. of

  command or value of the quantity to be injected.

  Thus, it is for example possible to maintain constant, independently of the start of the injection, the torque delivered by the engine at

internal combustion.

  According to another improvement of the invention, the signal indicating the amount of fuel depends on the wish of the driver and / or the desired rotation torque and corrected according to a

  signal indicating the beginning of the injection.

  According to another improvement of the invention, the signal indicating the quantity of fuel is delivered at least at a characteristic field as a function of the speed of rotation of a signal indicating the beginning of the injection and the

desired torque.

  According to another improvement of the invention, a set value for the second control device is delivered at least to a characteristic field as a function of the speed of rotation, a signal indicating the beginning of the injection, and of a

  signal indicating the amount of fuel.

  According to another improvement of the invention, the characteristic field takes into account the fact that the set value for the second control unit must be corrected according to the signal indicating the start of the injection, the speed of rotation and the duration of the injection. According to another improvement of the invention, the setpoint value for the position of the first control device or a signal, which indicates the effective position of the first control device, serves as a signal indicating the start of the injection. According to another improvement of the invention, the set value for the position of the first control device depends at least on the desired amount of fuel and the speed of rotation. According to another improvement of the invention, it is for the first device of

  controls a reciprocating drawer.

  According to another improvement of the invention, it is for the second control device a device moving the control rod. According to another improvement of the invention, the characteristic field consists of at least three characteristic fields, each for a fixed injection start, a set value for the second control device being determined from these three characteristic fields by

interpolation.

  According to another improvement of the invention, the set value for a start of the average injection is delivered to a characteristic field and difference values are delivered to other characteristic fields or are delivered in the other characteristic fields for

  the beginnings of injection large and small.

  The invention will be described below with the aid of the embodiments shown in the drawings. Figure 1 shows a rough diagram

  by blocks of the control system according to the invention.

  Figure 2 shows the curve of the quantity of fuel discharged as a function of the angle

of cam.

  Figures 3a and 3b show diagrams for clarifying the method according to the invention. In what follows, the system according to the invention will be described as an example of a reciprocating spool pump. However, the system according to the invention is not limited to the use of a reciprocating spool pump. The system can also be used in other high-pressure fuel pumps, where the start of the injection and the amount of fuel can be adjusted.

  inject independently of one another.

  FIG. 1 shows the block diagram of the metering system according to the invention. A control device, in the following designated as the first control unit determining the start of the discharge or the beginning of the injection and a second control device, in which the following designated as second control unit determining the amount of fuel to be injected, are each adjusted by means of a control circuit An internal combustion engine 10 receives the

  fuel required for combustion through

  of a high pressure fuel pump.

  In doing so, a sensor 30 records each start of fuel injection, i.e. the start of the injection or the beginning of the delivery of the fuel pump. It is also possible for a sensor to detect the actual position of the fuel pump. 'a first

control unit 80.

  A sensor 40 records a signal, which corresponds to the amount of fuel supplied to the internal combustion engine 10. This is usually the position of the control rod.

normal) RW 1.

  In other types of pumps, it is also conceivable that a signal, such as the duration of the injection or other signals, which represents a

  measuring the quantity to be injected, are used.

  Different sensors 50 record the state of operation of the internal combustion engine 10 There is thus provided a sensor, which records the speed

  rotation N of the internal combustion engine.

  The output signal of the sensor 30, via a subtraction point 60, reaches a first regulator 70, which acts on the first control unit 80 This first control unit 80 triggers the start of the fuel metering At the second input of the point subtraction 60 is the SBS output signal of a characteristic field 90, which provides a set value for the start of the injection This characteristic field 90 receives from a calculation unit 100 signals relating to the rotational speed and the amount of fuel

desired QK.

  The sensor 40 records the actual control path (effective control path value) RWI of the control rod This signal reaches a subtraction point 110 Depending on the output signal of the subtraction point 110 a second regulator 120 determines a signal for a second control unit 130, which acts on the quantity of fuel supplied to the internal combustion engine In this embodiment, it is this control unit that moves the rod correspondingly

control.

  At the second input of the subtraction point 110 is an output signal of a characteristic field 140, which provides a set value for the control rod position. This characteristic field 140 for the control path

  receives different signals from the computing unit 100.

  For example, a signal which indicates the speed of rotation and a signal which indicates the desired quantity of fuel QK The output signal of the first regulator 70 or the output signal of the characteristic field 90 reaches the characteristic field 140. The calculation unit 100 comprises, inter alia, a motor characteristic field 170A which also receives the output signal of the characteristic field 90 or the output signal of the first controller 70 Signals which indicate the desired torque MD and the speed of rotation N

  reach the characteristic field 170.

  The calculating unit 100 retrieves different signals For some these are signals, which are taken with the help of sensors on the internal combustion engine, for the rest they are signals of other sensors 160 for example for the temperature air, air pressure or the temperature of the fuel A device 150 delivers a signal, which indicates the wish of the driver, in the simplest case it is the value detector of the accelerator pedal. The operating mode of the control system is as follows: The calculation unit 100 calculates according to various parameters, such as the wishes of the driver, the desired torque, the external constraints of the environment, as well as different operating parameters of the internal combustion engine the

  desired amount of fuel QK.

  It is advantageous in this respect for the computing unit to retract a signal with respect to the engine torque desired. In this case, it is necessary to have the engine's characteristic field, which provides the fuel quantity. to inject QK according to different values as per

example the rotation torque.

  The signal QK which corresponds to the desired fuel quantity, as well as the signal of the speed of rotation N arrive for one, at the characteristic field 90 for the beginning of the injection and / or the other, at the characteristic field 140 for the journey

control.

  In some cases, it is advantageous

  to install a regulation of the torque.

  This is for example the case when for an operating point of the engine different values of

  Injection start setpoint can be provided.

  An operating point of the motor is then defined by a constant torque and a constant speed of rotation. Depending on the desired torque, the speed of rotation N and the beginning of the injection, the characteristic field 170 of the motor provides a value for the quantity of fuel to be injected. QK It is then particularly advantageous to choose a value for the quantity of fuel to be injected from the characteristic field 170 of the engine as a function of a comparison between the

  desired torque and effective torque.

  From the characteristic field 90 for the beginning of the injection, a set point value of the start of the injection SBI is chosen. This value is compared with the point of subtraction 60 with the starting setpoint value of the effective injection SBI. As a function of the comparison between the set point and the actual value for the start of the injection, the first regulator 70 calculates a control signal for the first control unit 80. The first regulator contains for this purpose a characteristic field for large opening stroke This field delivers a value, which indicates the position of the first unit

control.

  The characteristic field sends, to the second regulator 120 as a function of the rotational speed and the desired fuel quantity, a set value RW for the control path. This path is compared to the subtraction point 110 with the actual control path RWI recorded. by the sensor 40 Depending on the results of this comparison the second regulator 120 produces a signal This signal

  adjusts the control unit accordingly.

  The first control unit 80 determines the start of the injection of the fuel pump and the second control unit 130 determines the duration of the injection of the fuel pump. The two control units 80, 130 can be designed as pure control units, that is to say that the control unit takes the position provided by the output signal of the controller On the other hand, it is advantageous that each regulator supply the current passing through the unit A control unit sensor records the current flowing through the control unit A control unit controller compares this current to a set value for the control unit current supplied by each controller and calculates a new control current based on this comparison. For the first control unit, it is particularly advantageous for the first controller to give a set value for the position of the control unit. A first control regulator adjusts the actual position of the first control unit.

  command on the set value provided.

  Such a control system works satisfactorily only if the offset of the start of the injection has no influence on the quantity injected. If this is not the case, this influence must be taken into account. the influence of the start of the injection on the quantity of fuel injected and taken into consideration by sending a signal which indicates the beginning of the injection, to the characteristic field 140 for the

control path.

  It is thus possible to send to the characteristic field 140 a signal which indicates the position of the first control unit. Such a signal is, for example, the output signal of the first controller. If the installation comprises a first control regulator, which regulates the position of the first control unit. first control unit on a given position by the first regulator 70, it is also possible to use the effective value -or the setpoint value of this first control regulator. If this is not the case, the output signal of the first is extracted. regulator 70 This signal corresponds to the value of

  setpoint of the first control regulator.

  It is particularly advantageous if the output signal of the characteristic field 90 for the set value of the start of the injection is extracted for correction. This solution has the advantage that it is not necessary to have a feedback signal of

  the position of the control unit.

  In addition, such a control system works satisfactorily only if the offset of the start of the injection has no influence on the rotational torque delivered by the internal combustion engine. If this is not the case, it This influence must be taken into account. According to the invention, the influence of the beginning of the injection on the rotational torque is taken into consideration, by sending a signal, which indicates the beginning of the injection, to the characteristic field 170 for the quantity of fuel to be injected QK It is then particularly advantageous during this correction to extract for correction the output signal of the characteristic field 90 for

  the set value of the start of the injection.

  FIG. 2 shows the need for correction of the control path as a function of the beginning of the injection. In FIG. 2, the axis of the x is taken to be the angle of rotation of the cam NW and on FIG. y-axis the amount of fuel injected QK For two different injection starts, two assays were taken at different lengths At the same time, the amount of fuel injected was plotted. SBA injection and a dosage for the beginning of the SBB injection with the duration D1 and a dosage with the duration D 2 The dosage corresponding to the duration D 2 is then greater than one

  factor 2 that the dosage corresponding to the duration Dl.

  If the dosing corresponding to the discharge time D1 occurs at the beginning of the injection SB 1, then a quantity Q Al is obtained. At the beginning of the injection SBB, on the other hand, a quantity QB 1 is obtained. The quantity discharged QB 1 is then larger by a given factor Fl (in this example a factor

  of 1,2) that the amount repressed QA 1.

  If a dosage corresponding to the duration D 2 occurs at the beginning of the injection SBA, a quantity of discharge QA 2 is obtained. For the determination at the beginning of the injection SBB, on the other hand, a reprocessed quantity QB 2 is obtained. In this case, the quantity repressed QB 2

  is greater by a factor F 2 than the quantity QA 2.

  Depending on the discharge time and the control path (position of the control rod), different factors are thus obtained for the ratio between the amount of discharge QB (dosage at the beginning of the injection SBB) and the quantity of discharge QA. (dosing at the start of the SBA injection) If the set point correction for the control rod position only depends on the start of the discharge and the rotation speed as in the state of the art, we obtain then false values This correction must, according to the invention, also depend also on the duration of the injection, or a signal that represents a measure of the duration of the fuel dosage For such a signal, we can consider the duration the duration of the injection, the set value of the control path RW, the set value of the quantities to be injected, the actual value of the control path RWI or the difference between

  the beginning of the injection and the end of the injection.

  For carrying out the correction, the control path as a function of the start of the injection and the quantity injected, different possibilities according to the invention are provided, which are shown in FIG. 3. Simple and advantageous In the characteristic field 140, the command path setpoint is defined as a function of the desired injected quantity, the rotation speed, and a signal indicating the start of the injection. For example, it is possible to use the actual value or the setpoint value of the controller for the position of the first control unit or the control unit. current of the control unit For the rest, we can think of using the

  output signal of the first controller 70.

  If none of these signals are available, it is also possible to extract another suitable substitution quantity. In the systems controlled by a solenoid valve, it is for example thinkable.

  to extract the instant of the switching of the electro-

  valve. This characteristic field assumes that the set value RW for the second control unit 130 can be corrected, depending on the start of the injection, the speed of rotation and the speed of rotation.

  the set value of the quantity to be injected.

  With this condition of proceeding, it is possible to have a complete correction of the influence of the beginning of the injection on the quantity of fuel injected. The four-dimensional characteristic field 140 represents the inversion of the hydraulic properties of the pump. , that is, the characteristic field of the amount discharged For the characteristic field of the quantity discharged, the quantity injected should be a function of the effective value of the control path, the speed of rotation and the start of the discharge For the characteristic field of the pump, the setpoint of the control path is a function of the desired fuel quantity, the speed of rotation and the start of the discharge This procedure ensures a constant quantity of injection for a desired fixed quantity, fuel data for each speed of rotation and each start of discharge that we want It is necessary to consider the influence of the fuel temperature on the quantity discharged for example by an enlargement of the characteristic field of a certain dimension. This characteristic field must take into account the fact that the set point must be corrected for a quantity of fuel at

  inject QK according to the beginning of the injection.

  Figure 3b shows in detail the construction of the characteristic field. Since the characteristic fields are generally constructed in three dimensions, but as here a four-dimensional characteristic field is necessary, several characteristic fields have been drawn side by side. In this way, it is possible to use simpler and more economical memory elements. The various characteristic fields 310, 320 and 330 are each represented by a constant injection start. The calculation of each command path setpoint value in FIG. function of the start of the injection SB takes place inside a calculation stage 300 by

interpolation.

  A first embodiment project is shown in FIG. 3c. For this embodiment, three characteristic fields were needed. They correspond to a characteristic field for each abutment of the control unit of the beginning of the injection and a field characteristic for an average position of the control unit of the start of the injection On the characteristic field 310, the reference value of the control path RW (G) was shown for the starting value of the largest injection possible SBG On the characteristic field 320, the control path setpoint RW (M) is drawn for an average injection start value SBM and on the characteristic field 330 the control path setpoint RW (K) is drawn for the smallest injection start value possible. In a first step 350, this start of the injection SB is recorded. On the one hand, it is possible to use the start of the delivery of the pump or the actual start of the injection and, on the other hand, it is also possible to extract the measured position. of the first control unit, the set point for the start of the injection or the setpoint

  current for the controller of the control unit.

  At the recording of the beginning of the injection is associated a decision stage 360, which controls if the start of the injection SB is greater than a threshold value. This interrogation determines whether the start of the injection is larger or smaller than the average start of the SBM injection If this is the case, a calculation is performed according to the following formula:

  RW = RW (M) + (RW (G) RW (M)) * (SBX-SBM) / (SBG-SBM)

  In this formula RW designates the desired control path setpoint value for the start of the actual injection SBX. This control path setpoint value RW is calculated by the calculation unit 300 according to the formula above and issued as

calculation is done in block 370.

  If it results from the interrogation 360 that the start of the injection is smaller than the threshold value, then a corresponding calculation is made in block 380 according to the following formula

  RW = RW (K) + (RW (M) RW (K)) * (SBX SBK) / (SBM SBK)

  In a second embodiment in a characteristic field 320 the control path RW (M) is established as a function of the rotational speed and the quantity of fuel for an average injection start value. For the remainder on the characteristic field 310 DRW (K) characteristic field values are set for smaller injection start values, and on the characteristic field 330 DRW (G) difference field characteristic values are set for larger values. start of the injection according to the speed of rotation and

the amount of fuel.

  The calculation is also done as

  represented in FIG. 3c in blocks 370 and 380.

  For small values of beginning of the injection, one uses the formula:

  RW = RW (M) + DRW (K) * (SBM SBX) / (SBM SBK)

  For large values of the beginning of the injection, we use the formula

  RW RW (M) + DRW (G) * (SBM SBM) / (SBG SBM)

  In this case the magnitude of the control path (RW) only needs to be replaced by the magnitude of the quantity of fuel to be injected QK and the quantity of fuel to be used.

  inject QK by the magnitude of the rotational torque MD.

  By this way of proceeding, it is possible to have a complete correction of the influence of the beginning of the injection on the rotational torque delivered. For the characteristic field of engine 170, the quantity of fuel to be injected QK represents a function of desired torque, speed of rotation and start of injection This procedure ensures a constant torque for the speed of rotation and the start of the injection.

we want.

  The process is particularly advantageously used in fuel pumps in which the start of the injection can be adjusted independently of the amount of fuel discharged. This is for example the case in reciprocating spool pumps. of pumps, there is provided a first control device for the position of the slide and a second control device for the control rod The control rod determines the amount of fuel to be injectedThe position of the slide determines the start of

injection.

  In such a system, it is particularly advantageous to use the setpoint value or the actual value for the slide position in place of the start of the injection for the correction. This value can simply be derived from the output signal of the characteristic field. 90 It is therefore not necessary to have other sensors The system also has a higher reliability in relation to the device in which the start of the injection is recorded by means of a separate sensor. In another configuration, it is expected that the actual position of the drawer is recorded. This signal is sent to the characteristic field 140 for the command path setpoint or to the characteristic field 170 of the motor. However, this device has the disadvantage that the sensor may be defective It has in relation to the use of the setpoint the advantage that one has a very exact signal in this

  which concerns the beginning of the injection.

  But it can also be used in fuel pumps in which the start of the injection and the end of the injection are determined by means of solenoid valves In these systems, the moment of engagement or the moment triggering of a solenoid valve determines the beginning

  or the end of the discharge of the fuel pump.

  When switching to such systems, the system described here is correspondingly established and the signals

  correspondents can or should be applied.

Claims (2)

  1) A control system for a self-igniting internal combustion engine, with a first controller (80), which determines the commencement of fuel injection, and a second device (130), which determines the amount of fuel to be ignited. injecting (QK) a setpoint value (SBS) for the first control device (80) being outputted according to different operating parameters at least to a characteristic field (90), characterized in that a setpoint value (RW) for the second controller (130) is corrected according to a signal indicating the start of the injection and a signal indicating the amount of fuel (QK).   Control system for an internal combustion engine according to claim 1, characterized in that the signal (QK) indicating the amount of fuel depends on the desired conductor and / or torque (MD) and corrected in accordance with a signal indicating the beginning of the injection. A control system for an internal combustion engine according to claim 1 or 2, characterized in that the signal (QK) indicating the fuel quantity is supplied to at least one characteristic field (170) as a function of the rotational speed. a signal indicating the start of the injection   and the desired rotation torque (MD).   40) Control system for an internal combustion engine according to any one of   Claims 1 to 3, characterized in that, a   setpoint (RW) for the second controller (130) is outputted at least one characteristic field (140) as a function of the rotation speed, a signal indicating the start of the injection, and a signal indicating the amount of fuel (QK).   ) Control system for an internal combustion engine according to any one of   Claims 1 to 4, characterized in that the field   characteristic (140) takes into account that the set value (RW) for the second control unit (130) must be corrected according to the signal indicating the start of the injection, the   speed of rotation and the duration of the injection.   ) Control system for an internal combustion engine, according to any one of   Claims 1 to 5, characterized in that the value   set point (SBS) for the position of the first controller or a signal, which indicates the actual position of the first controller,   serves as a signal indicating the start of the injection.   ) Control system for an internal combustion engine according to any one of   Claims 1 to 6, characterized in that the value   set point (SBS) for the position of the first controller depends at least on the quantity   desired fuel and rotational speed.   80) Control system for an internal combustion engine according to any one of   Claims 1 to 7, characterized in that it is   for the first control device a drawer to reciprocating motion.   90) Control system for a motor   combustion according to any one of claims 1   8, characterized in that it is for the second control device of a device displacing the control rod.   10) Control system for a motor   combustion according to any one of claims 1   at 9, characterized in that the characteristic field (140) consists of at least three characteristic fields, each for a fixed injection start, a set value for the second control device being determined from   these three characteristic fields by interpolation.   1) Control system for an internal combustion engine according to any one of   Claims 1 to 10, characterized in that the value   set point for a start of the average injection is delivered to a characteristic field and difference values are delivered to other characteristic fields or are delivered in the other characteristic fields for injection start big and small.