FR2747428A1 - METHOD AND DEVICE FOR CONTROLLING AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

Method and device for controlling an internal combustion engine, characterized in that a pressure signal depending on the pressure in the low pressure zone is preset and in that the fault signal and the pressure signal are reprocessed to detect defects .

Description

State of the art

  The invention relates to a method and a device

  tif for controlling an internal combustion engine in which the fuel is transferred by at least one pump from a low pressure zone to a high pressure zone and from there the fuel can be metered by means of the injectors of the internal combustion engine, so that we can

predefine a fault signal.

  Such a method and such a device is known from DE-OS 1 95 20 300. In this document there is described a method and a device for controlling an engine.

  internal combustion engines, with which the fuel is

  at least one pump from a low pressure zone in a high pressure zone and from there can be determined by means of

  injectors of the internal combustion engine. Such

  Positives are usually referred to as "Common-Rail" systems. This device comprises a first means

  which prepares a fault signal in the event that it occurs

  a fault in the high pressure zone. To detect a fault the device controls the fuel pressure

  in the high pressure zone. If the pressure falls

  under a predetermined value, it is thus detected that there is

failure.

  This lowering of the pressure in the high pressure zone does not necessarily arise on a fault in the high pressure zone, but can also be based on a

  fault in the low pressure zone.

  Object of the invention The object of the invention is, in the case of a method and a

  device for controlling an internal combustion engine

  dull type of the type mentioned at the beginning, to distinguish between defects in the low pressure zone and in the high pressure zone. This problem is solved by virtue of the fact that a pump characterized in that a pressure signal which is a function of the pressure in the low pressure zone is predefined and in that

  that the fault signal and the pressure signal are

  processed to detect defects.

  Advantages of the invention With the device according to the invention, it is possible to distinguish clearly between defects in

  the low pressure zone and in the high pressure zone.

  For example, it is possible to safely detect an empty tank or other disturbances on the

  low pressure. It is safe to avoid incorrect diagnoses

  1 <) roned in the high pressure zone.

  According to other features of the invention - a defect in the high pressure zone is then recognized only when the fault signal exists and

  when the pressure signal takes predefined values

  ble; - no fault is detected when the pressure

  in the low pressure zone is smaller than a range

their threshold;

  the pressure signal takes a first

  their when the pressure in the low pressure zone is greater than a threshold value; a fault is recognized in the high pressure zone only when the fault signal exists and when the pressure signal takes its second value; - after a disconnection due to a fault in the high pressure zone a new start of the internal combustion engine takes place only when the pressure in the

  Low pressure area is smaller than a threshold value.

  The invention also relates to a device 3 for implementing the method for controlling an engine

  internal combustion engine, in which the fuel is transferred

  by at least one pump of a low pressure zone in a high pressure zone and from there, the fuel can be metered by means of the injectors of the internal combustion engine so that a fault signal can be predefined,

  characterized in that second means are provided which

  define a pressure signal depending on the pressure in the low pressure zone and in that means are provided which reprocess the fault signal and the pressure signal to detect faults. Drawings The present invention will be described hereinafter in more detail from several embodiments shown in the drawings in which: - Figure 1 shows a block diagram of the device according to the invention and - Figure 2 shows a schematic diagram of the mode of

operation according to the invention.

  Description of the embodiments

  FIG. 1 shows the elements of an embodiment of a feed system of

  fuel with high pressure injection. The system

  presented is usually referred to as a system

"Common-Rail".

  Reference 100 has been designated a fuel tank. This is connected by means of a first filtering means 105 with a transfer pump 110 preferably adjustable and with a second filtering means 115. The fuel arrives from the second filtering means 115

  through a 120 valve line.

  connection between the filtering means 115 and the valve

  connected via a limit valve

  The valve 120 is connected via a pump 3 (high pressure 125 with a rail 130). The rail is in contact with the tank 100.

  through fuel lines with different

  injector 131. It can be connected by means of a valve

  setting the pressure 135 the rail 130 to the tank of car-

  110. The pressure regulating valve 135 may

  be controlled by means of a coil 136.

  The area between the output of the high pres-

  125 and the inlet of the pressure control valve is designated as the high pressure zone. In this

  zone the fuel is under high pressure. Usual-

  In the case of systems with internally ignited internal combustion engines, pressure values of 30 to 100 bar are obtained, and in the case of self-igniting internal combustion engines, values of the pressure of 30 to 100 bar are obtained. 100 to 2000 bars. Pressure

  in the high pressure zone is detected by means of a

tector 140.

  The area between the fuel tank

  and the high pressure pump 125, particularly the area between the supply pressure pump 110 and the high pressure pump 125 is designated as the low pressure zone. In this low pressure zone a second pressure detector 170 has been arranged, which prepares a PN signal, which is a measure of the fuel pressure in the low pressure zone. In the example embodiment

  the simplest is only a manometer

  that, which prepares a first signal value below a PS threshold value for the pressure and prepares a

  second signal value above the threshold value.

  The position shown in Figure 1 is only one possible mounting location. The detector 170 may also be disposed between the valve 120 and the high pressure pump 125. The pressure detector 170 is

  preferably arranged between the feed pressure pump

  110 and the high pressure pump 125 and / or between a not shown shut-off valve and the high pressure pump 125. The sensor 170 is mounted as close as possible.

  as possible from the high pressure pump 125.

  The injectors 131 and the valve 136 of the pressure control valve 135 solicited by a control by control signals. The retirement order

  signals from different detectors 160.

  This device operates in the following way: the fuel which is in the tank, is transferred by the supply pressure pump 110 through the filtering means 105 and 115. On the output side of the

  feed pressure pump 110 the fuel is fed

  under a pressure of between 1 bar and

  Viron 3 bars. When the pressure in the low pressure zone of the fuel system has reached a predefined value, the valve 120 opens and the inlet of the high pressure pump

  is fed by a determined pressure. This pressure

  sion depends on the realization of the valve 120. Usually

  the valve 120 is constructed in such a way that it releases the connection to the high pressure pump when

the pressure is about 1 bar.

  If the pressure increases in the low pressure zone to a high value in an unauthorized manner, the low pressure limiting valve 140 opens and releases the connection between the outlet of the feed pressure pump 110 and the tank 100. By means of the valve 120 and the valve for limiting the low pressure to

  values between about 1 and 3 bar.

  The high pressure pump 125 transfers the fuel

  low pressure zone in the high pressure zone.

  The high pressure pump 125 establishes in the rail 130 a very high pressure. This pressure is included

  in an order of magnitude of 1000 to 2000 bar. Via the in-

  jectors 131 the fuel can be dosed under high pressure.

  for the different cylinders of the internal combustion engine. Usually the injector is so constituted that a dosage is only possible when the pressure in the high pressure zone is above a minimum value. Below a determined value

  pressure no injection is no longer possible.

  By means of the detector 140 the pres-

  in the rail or in the entire high pressure zone. By means of the pressure control valve 135, which can

  be controlled by a coil 136, it is possible to adjust the pressure

  in the high pressure zone. Depending on the voltage

  applied to the coil 136 or the intensity passing through

  to the coil 136 the pressure control valve 135

  opens at different values of the pressure.

  As the supply pressure pump 110 electric fuel pumps are usually used

  with a DC motor (DC motor) or with a motor

  electrically commutated DC motor (EC motor).

  For higher transfer rates, which are required

  particularly in the case of commercial motor vehicles, it is also possible to use

  power supply connected in parallel. In this case we use

  reads EC engines preferably because of their duration

  higher life and higher availability.

  The control 150 calculates, starting from the output signals of the various detectors 160, signals for soliciting the injectors 131, which are controlled by

  a predefined amount of fuel is injected

at a predefined time.

  In addition it forms a signal, such as the valve

  pressure regulator 135 is actuated with a

  as it opens in the high pressure zone

  when the pressure reaches a defined value. We can

  apply the pressure in the high pressure zone using

control signal.

  If the command 150 detects that a defect is

  has occurred, a defect can for example be detected by exploiting

  both the signal PH at the pressure detector 140 in the high pressure zone and / or different detector signals, a fault relation is then introduced. For example, a motor disconnection is

internal combustion.

  In Figure 2 there is shown a subprotocol

  control program in the form of functional diagrams.

  In the partial figure 2a there is shown a sub-

  control program of the low pressure zone. At the

  When the 200 routine starts, the subprogram starts. This subroutine is

  for example activated at fixed times or after the

  during a given angular zone. He is particularly

  advantageous that the activation takes place after a

  fault detection in the high pressure zone.

  By interrogation 210 which follows it is checked whether the pressure PN in the low pressure zone is smaller than a threshold value PS. If this is the case, the sequence 220 is set to zero an NF indicator. If, during the interrogation 210, it is detected that the pressure is greater than the threshold value PS, the indicator NF is then set to 1 on the sequence 225. As a result of the sequences 220 and 225, respectively, the sequence 230

back to the program.

  In Figure 2b there is shown a sub-

  program to control the high pressure area. At the

  this sub-program starts at the beginning of

  following derogation 245, it is checked whether there is a fault in the high pressure zone. For this we exploit for example

  the pressure PH in the high pressure zone. If there is a

  HF must be set to 1. If during the interrogation 245 it is detected that there is no fault, then the sequence 255 returns to the main program. Similarly following sequence 250 takes place at the 255 sequence the return to the

main program.

  In the partial figure 2c there is shown a

  sub-program, which preferably takes place during the

  rage of the internal combustion engine. Following the start

  The sequence 260 follows the interrogation 265 in which it is checked whether the HF error memory is set to 1. If this is not the case, then the normal course of the program follows the sequence 280. defects is set, that is to say, if it occurred during the previous operation of the internal combustion engine a defect in the high pressure zone, then 270 is entered interrogation. interrogation 270 it is checked whether the memory is set to 1. If this is not the case, the sequence 280 also follows. If the NF memory is

  set to 1, the program ends at sequence 275.

  The program ends at sequence 275, when the pressure PN in the low pressure zone is greater than the set value. If the pressure is lower than the threshold value PS, then there is

  no fault in the high-pressure zone, but the

  was based on a fault in the low pressure zone and it is then possible to have normal operation

of the internal combustion engine.

  If a disconnection has occurred due to a fault in the high pressure zone, then a new start of the internal combustion engine occurs if the pressure in the low pressure zone, when a fault occurs, is smaller. than a threshold value. In the event of an emergency disconnection in the event of a fault, it is

  possible to have a renewed start of the combustion engine

  tion, when the defect was in the zone

  low pressure. This is the case, for example, when the

  was emptied. In case of defects however in the

  high pressure zone a renewed start is not possible

corn.

  It is particularly advantageous that the con-

  check whether the pressure in the lower zone

  is greater than a PS threshold value, takes place

  after a fault detection in the high pressure zone.

  This means that the interrogation 210 of FIG.

  connects to the sequence 250 in the partial figure 2b.

  This particular configuration is represented on the

  partial gure 2d. The corresponding blocks are designated by corresponding references. If a fault in the high pressure zone is detected at the sequence 245, and it is found during the interrogation 210 that the pressure PN in the low pressure zone is greater than a threshold value PS the sequence 290 is recognized as having a fault in the high pressure zone and corresponding measurements are introduced, such as emergency disconnection. In the other cases, that is to say when during the interrogation 245 one does not detect a fault, or during the interrogation 210 one detects that the pressure in the low pressure zone is smaller than the value of threshold, the

  back to the main program takes place at the 255 sequence.

  A fault in the high pressure zone is only recognized when there is no fault in the low pressure zone. Thanks to this mode of operation it is possible to avoid emergency disconnections, which are caused by defects in the low pressure zone. The disadvantage with respect to the previous embodiment is, however,

  that emergency disconnection is slightly delayed.

Claims (6)

R E V E N D I C A T IONS   1) Method for controlling an internal combustion engine   in which the fuel is transferred by at least one pump from a low pressure zone into a high pressure zone and from there the fuel can be metered by means of the injectors of the internal combustion engine, so that a fuel can be predefined. fault signal, characterized in that a pressure signal depending on the pressure in the low pressure zone is predefined and in that the fault signal and the pressure signal are reprocessed to detect faults.   2) Method according to claim 1, characterized in that a defect is then recognized in the high pressure zone only when the fault signal exists and when the signal of   pressure takes predefined values.   3) Method according to one of the preceding claims,   characterized in that a fault is not detected when the pressure in the zone   Low pressure is smaller than a threshold value.   4) Method according to one of the preceding claims,   characterized in that the pressure signal takes a first value, when the pressure in the low pressure zone is greater than threshold value.    Method according to one of the preceding claims,   characterized in that a fault is recognized in the high pressure zone only when the fault signal exists and when the pressure takes its second value.   6) Method according to one of the preceding claims,   characterized in that after a disconnection due to a fault in the high pressure zone a new start of the internal combustion engine takes place only when the pressure in the low zone   pressure is smaller than a threshold value.   7) Device for implementing the method for comparing   an internal combustion engine, in which the car-   burant is transferred by at least one pump from a low pressure zone into a high pressure zone and from there the fuel can be metered by means of the injectors of the internal combustion engine so that a fault signal can be predefined, characterized in that second means are provided which predefine a pressure signal depending on the pressure in the lower zone   pressure and that means are provided for   the fault signal and the pressure signal to de- detect faults.