FR2744765A1 - METHOD AND DEVICE FOR CONTROLLING AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

Method for controlling an internal combustion engine with high pressure injection, in particular an internal combustion engine equipped with a common rail system (130), the fuel being transferred by at least one pump (125) from a low pressure zone to a high pressure zone and from there it is injected in a metered manner by injectors (131) into the internal combustion engine, the pressure in the high pressure zone being detected by a pressure sensor (141) and being adjusted by means of pressure regulating means (135), characterized in that in the event of detection of a fault, the pressure regulating means (135) is controlled to drop the pressure in the area high pressure at a value no longer allowing an injection.

Description

State of the art.

  The invention relates to a method for controlling an internal combustion engine with high pressure injection, no-

  an internal combustion engine fitted with a common rail system, the fuel being transferred by at least one pump from a low pressure zone to a high pressure zone and,

  from there, it is injected in a metered manner by injectors into the internal combustion engine, the pressure in the high pressure zone being detected by a pressure sensor and re-adjusting with the aid of a regulation means. pressure.

  The invention also relates to a device for

  high-pressure injection internal combustion engine control

  sion, in particular an internal combustion engine fitted with a

  common rail system, comprising at least one transfer pump

  fuel from at least one low pressure zone to one zone

  high pressure, injectors supplying fuel for

  dosed to the internal combustion engine, a pressure sensor

  fuel pressure sensing in the high pressure zone and a pressure regulating means for setting

process work.

  According to the methods and devices for controlling internal combustion engines, the fuel is transferred by

  a pump from the tank, and through fuel lines

  rant, towards the injectors. In the case of internal combustion engines with high pressure injection, in particular internal combustion engines with uncontrolled ignition, downstream of the fuel transfer pump, there is another pump which provides a very high pressure for the area high pressure of the fuel supply system. The high pressure zone communicates

  with the injectors. In addition, a regulating valve is provided.

  pressure lation to adjust the pressure in the

high pressure area.

Subject of the invention.

  The object of the present invention is to develop a method and a device for controlling a combustion engine.

  internal allowing rapid shutdown of the internal combustion engine

dull in the event of a defect.

Advantages of the invention.

  To this end, the invention relates to a method of the type defined above, characterized in that in the event of detection

  If there is a fault, the pressure regulating means is controlled to drop the pressure in the high pressure zone to a value

  no longer allowing an injection.

  The invention also relates to an installation for implementing this method, characterized in that in the event of a recognized fault, the pressure regulating means is controlled so that the pressure in the high pressure zone drops

  to a value no longer allowing injection.

  According to other advantageous characteristics of the process:

  - in the event of a recognized fault, in addition, the injectors are com-

ordered not to inject anymore.

  -a fault is detected, especially when there is a leak.

  -for certain operating states we check the suitability

  during operation of the pressure regulating means.

  - verification is done in push mode.

  - for verification the control means of

  pressure to produce a pressure drop.

  - it is considered that the pressure regulating means is suitable

  to operate if the pressure drops by a predetermined value

born.

Drawings.

  The invention will be described below in more detail

  detailed using an exemplary embodiment shown diagram

  matically in the accompanying drawings in which:

  - Figure 1 shows a block diagram of the arrangement

  sitive according to the invention, - Figure 2 shows a flowchart of the method of the invention.

  Description of the exemplary embodiment.

  FIG. 1 shows the components of a fuel supply system of an internal combustion engine with high pressure injection, necessary for understanding the invention. The system represented is usually called

"common rail" system.

  The reference 100 designates a fuel tank.

  This tank is connected via a first filter to an adjustable supply pump 110 with, downstream thereof, a second filter 115. The fuel having passed through the second filter 115 arrives via a line with a valve. 120. The connecting pipe between the filter 115 and the valve 120 is connected to the tank 100 by a low pressure limiting valve 140. The valve 120 is connected by a high pressure pump 125 to a rail 130. The rail is connected to the various injectors 131 through fuel lines. A pressure regulating valve 135 connects the rail 130 to the reservoir of

  fuel 110. The pressure regulating valve 135 consists of

  driven by an electromagnetic coil 136.

  The area between the outlet of the high pump

  125 pressure and the inlet of the pressure regulating valve

  sion 135 is called the high pressure zone. In this area, the fuel is always at high pressure. Usually for

  internal combustion engine systems with spark ignition

  dice, pressures of the order of 30 to 100 bars are reached; in the case of internal combustion engines with uncontrolled ignition, pressures of 1000 to 2000 bars are reached. The pressure in

  the high pressure zone is detected by a sensor 141.

  The injectors 131 and the coil 136 of the pressure regulating valve 135 receive control signals from a control installation 200. The control installation

  processes the signals from the various sensors 210.

  The control system includes a first circuit

  control circuit 215 for the injectors 131, and a second circuit

  control circuit 220 for coil 136 of pressure control valve 135. The first and second control

  receive command signals from a function command

230.

  This installation works as follows:

  Vante: The fuel from the tank is transferred by the upstream pump 110 through the filters 105 and 115. At the outlet of the upstream pump 110, the fuel is at a pressure of approximately 3 bars. If the pressure in the low pressure area of the fuel system reaches a determined pressure, the valve 120

  opens and the inlet of the high pressure pump 125 receives a certain pressure. This pressure depends on the construction of the valve 120. Usually, the valve 120 is designed so that at a pressure of approximately 1 bar it releases communication with the high pressure pump 125.

  When the pressure in the low pressure zone

  turns an unacceptable level, the low pressure limiting valve 140 opens and releases the connection between the outlet of the upstream pump 110 and the tank 100. The valve 120 and the low pressure limiting valve 140 maintain the pressure in the low pressure zone at a level between 1 and 3 bars. The high pressure pump 125 transfers the fuel from the low pressure zone to the high pressure zone. The high pressure pump 125 establishes in the rail 130 a very high pressure. This pressure is of the order of magnitude from 1000 to 2000 bars. The injectors 131 can then dose the fuel at high pressure into the various cylinders of the internal combustion engine. Usually, the injectors are made to allow metered supply only if the pressure in the high pressure zone exceeds a minimum value. Below a certain pressure level, injection is no longer possible.25 Using the sensor 141, the pressure is measured in the rail or in the entire high pressure zone. Using the pressure regulating valve 135, which is controlled by the electromagnetic coil 136, the pressure in the high pressure zone is adjusted. Depending on the voltage applied to the coil

  136 or the current flowing through the coil 136, the pressure relief valve

  pressure control 135 opens for different pressure values. As upstream pumps 110, fuel pumps are usually used, electric, controlled by a motor with

  direct current or common DC motors

  you. For higher flow rates, necessary in particular on utility vehicles, it is possible to use several upstream pumps connected in parallel. In this case, because of their greater reliability, and their greater diffusion, we use

  preferably switched DC motors.

  In normal operation, the function control-

  nement 230 calculates the signals intended for the first installation

  control 215 according to the output signals of the

  different sensors 210. This first installation of

  command 215 controls the injectors 131 as a function of these

  so that they inject a predetermined amount of

fuel at a given time.

  In addition, this function control provides the second control installation with a signal such that the pressure regulating valve 135 receives a voltage to open the valve when a determined pressure prevails in the high pressure zone. This control signal regulates the prevailing pressure

in the high pressure area.

  When the operating command 230 finds a fault, which can for example be recognized by the use of the various sensor signals 210, this command transmits a signal to the first and to the second command to shut down the internal combustion engine. The signal applied to the first control installation 215 is such that the injectors do not

  provide more fuel to the internal combustion engine.

  The control signal for the second control system 220 is such that the pressure control valve opens

  completely to drop the pressure in the high pressure area as quickly as possible.

  It is particularly advantageous if the valve

  pressure regulator 135 is performed so that in function

  normal operation, without current, the pressure in the high pressure zone is lowered to a holding pressure of approximately 140 bars and that in the event of a fault it is nevertheless lowered to a level of 0 bar. This can for example be done by designing the pressure regulating valve 135 so that, by reversing the polarity of the voltage or by an additional control line, it is controlled to cause the pressure to drop to level 0 in the high pressure zone. The fall

  pressure in the high pressure zone to pro-

  ches de O bar results in very rapid engine shutdown

internal combustion.

  It is particularly advantageous in this process that the cut is made by two independent paths. On the one hand, this cut is made by a first path which ends the injection by the injectors 131. If this measure were not sufficient to shut down the internal combustion engine because the injectors would be defective and would continue to supply fuel from permanently, then the control of the pressure regulating valve would act by the second

  way to drop the pressure in the high area near

  so that there is no more injection or that it is no longer possible. Although the shutdown is designed redundantly, it does not require any additional line or any other component such as other shut-off valves.

  This procedure greatly reduces the time

  stop when the engine stops in the event of a fault since there is no longer any residual quantity in the high pressure area which would be under pressure and could be injected. In addition, the operation of this stop installation is verified during the operation of the engine. This is done for example in thrust mode (forced inertia). At this moment the pressure cut-off is briefly activated and the cut-off function is checked by

  sensing the pressure in the high pressure area.

  The method according to the invention is represented in FIG. 2 by a flow chart. In a first step 300, the presence of a fault is checked. This fault detection can be done by any methods. One can for example check the output signal of the pressure sensor 141 for

  know if the pressure takes on unacceptable values.

  If in step 300 a fault is detected, a fault bit F is set. This setting of the fault bit

  F can also be provided by another control unit.

  The fault bit F is set to the state when any vehicle control unit determines that the internal combustion engine must be shut down. This is for example the case if different faults are detected in the injection system, such as for example a permanent injection because of an injector which would remain attached, or even if external faults are signaled to the control unit . The interrogation 310 which follows verifies that the fault bit F is set to the state. If so, then the injectors are controlled in step 320 to prohibit fueling. Furthermore, in step 330, the electromagnetic coil of the pressure regulating valve 135 is controlled to allow for a rapid decrease in pressure. The pressure regulating valve is controlled so that the pressure decreases to a level such that there is no more injection. There is no need for this

  pressure decreases to atmospheric pressure

  than. The pressure drop in the common rail results in

  quence no longer allow injection and thus stop the internal combustion engine. Thus, the high pressure pump 125

  also no longer transfers fuel. An additional shutdown of the high pressure pump 125 or an interruption of the fuel flow to the high pressure pump 125 is not necessary.

  According to a simplified embodiment, only

  use only one of the two means in steps 320 and 330.

  The means used in step 330, consisting in controlling the

  electromagnetic coil of the pressure regulating valve

  sion 135 to allow a rapid decrease in pressure, sufficient to stop the internal combustion engine. The second means improves security in the event of possible faults at the level

  of the pressure regulating valve 135.

  It is particularly advantageous that the invention does not require additional components or lines of

  output from the control unit. For switching off in the event of

  must, we use means that are also necessary in

normal running.

  When the interrogation 310 finds that the fault bit F has not been set, we usually go to step 300. According to a preferred embodiment, there is then an interrogation 340 which checks whether is in

  push mode. If not, we go back to step 300.

  When the interrogation 340 finds a mode of operation in which there is usually no

  injection, it controls the verification of the high pressure regulating valve 135. Such an operating mode is, for example, that of the thrust mode. To check the suitability for operation, in the following step 350, a level is detected.

  old pressure calf PA. Then, in step 360, the electromagnetic coil 136 of the high pressure regulating valve 135 is controlled so that the pressure drops. Then in step 370, a new pressure is detected.

  their pressure PN. In step 380, the difference is determined.

  PD reference between the new PN value and the old PA value.

  The following query 390 checks whether the difference in pres-

  sion PD is greater than a threshold S. In the affirmative, the installation is considered to be operating correctly and we return to step 300. If not, in step

  395 there is emission of a fault signal indicating that the

  pure relief does not work properly.

  According to the invention, in thrust mode, it is checked that the pressure, when the pressure limiting valve is operated, drops from a predetermined value S to

during a given time.

Claims (7)

R E V E N D I C A T I 0 N S   1) Method for controlling an internal combustion engine   high pressure jection, in particular of an internal combustion engine equipped with a common rail system (130), the fuel being transferred by at least one pump (125) from a low pressure zone to a high pressure zone and, from there, it is injected in a metered manner by injectors (131) into the internal combustion engine, the pressure in the high pressure zone being detected by a pressure sensor (141) and adjusted using pressure regulating means (135), characterized in that   in the event of a fault detection, the pressure regulation means   sion (135) is controlled to drop the pressure in the   high pressure zone at a value no longer allowing injection tion.   2) Method according to claim 1, characterized in that in the event of a recognized fault, in addition, the injectors (131) are ordered to stop injecting.   3) Process according to any one of the preceding claims. tes, characterized in that   a fault is detected, especially when there is a leak.   4) Process according to any one of the preceding claims.   tes, characterized in that for certain operating states, the suitability for   operation of the pressure regulating means (135).    ) Method according to claim 4, characterized in that   verification is done in push mode.   6) Method according to any one of claims 4 or 5,   characterized in that for verification the control means of the   pressure to produce a pressure drop.   7) Method according to claim 6, characterized in that it is considered that the pressure regulation means (135) is   able to operate if the pressure drops by a predefined value.   8) Control device for internal combustion engine   high pressure connection, in particular of an internal combustion engine   dull equipped with a common rail system (130), comprising at least one pump (125) transferring the fuel from at least one low pressure zone to a high pressure zone, injectors (131) supplying the fuel in metered manner to the internal combustion engine, a pressure sensor (141) detecting the fuel pressure in the high pressure zone and means   pressure regulator (135) for the implementation of the   assigned according to claim 1, characterized in that in the event of a recognized fault, the pressure regulating means (135) is controlled so that the pressure in the high zone   pressure drops to a value no longer allowing injection.