FR2641327A1 - METHOD AND DEVICE FOR CONTROLLING A SAFETY STOP MEMBER IN INTERNAL COMBUSTION ENGINES, IN PARTICULAR DIESEL ENGINES - Google Patents

Abstract

Method and device for controlling a safety shut-off member in internal combustion engines, in particular diesel engines. Method characterized in that in the service station, and while the engine is running, the control step "ELAB control" is called when a service personnel presses the diagnostic button, and that by actuation of this diagnostic button, the ELAB is energized and the stopping of the engine is interpreted as an indication that the ELAB safety shutdown device is working correctly and that a diagnostic button is provided to be actuated by the personnel. 'maintenance in the maintenance station, button through which the "ELAB check" check step is carried out.

Description

"Method and device for controlling a safety shut-off device in

combustion engines

  internal, including diesel engines. "

  The invention starts from a method for controlling a safety device (redundant) in the form of an electromagnetic shut-off valve (ELAB) in internal combustion engines, in particular diesel engines, whose control system of the The amount of fuel is controlled by a diesel electronic control unit (EDC), the supply of fuel to the engine being interrupted by the safety stop device when a fault occurs. The invention also relates to a device for the implementation

  process of the invention.

  To ensure the electronic regulation of

  operation of internal combustion engines with

  ignition, ie diesel engines, to implement electric control systems controlled by electrical signals (DEOS 35 31 198), in which case instead of mechanical fuel metering and control systems a central control unit (SG) provides the necessary control signals. While mechanical fuel metering systems are reliable for diesel engines because of their operational safety, they are due to the circumstances, less able to account for the large number of different operating conditions. and

environmental influences.

  The implementation of electronic components in combination with a diesel electronic control (EDC) also makes it desirable also provisions concerning safety, control and emergency response, when the different constituent groups considered per se already offer opportunities for the detection of defects, and possibly for the elimination of defects. It is thus known, in the case of conventional line pumps and distribution pumps for diesel injection, in EDC (Electronic Diesel Control) applications to provide an electrical stop device in the form of an electromagnetic shut-off valve, abbreviated hereinafter as ELAB. In the case of faults in the control unit (SG), in the case of defective indicators, in the event of disturbances of faults in the cable or in the injection pump, this valve interrupts the supply of fuel

  diesel and thus allows a controlled shutdown of the engine.

  As this electrical stop device allows the emergency stop, in the event of dangerous operating conditions possibly occurring, such as "spontaneous accelerations" or "run-ups" of the diesel engine, the safety of the system depends on preponderant way, of

  operation of this electrical stop device.

  For this reason, continuous monitoring of the operation of ELAB during the lifetime of the

  concerned vehicle is desirable.

  The usual constitution of a fuel injection pump known for diesel engines (DE-OS 29 45 484) can then be such that a pump piston disposed in the case of the fuel injection pump, is aminated reciprocating movement, in which case fuel from the internal space, constituting the suction chamber, of the injection pump housing, reaches the piston pump. From there, the fuel arrives according to the quantities regulated in the pipelines of

  discharge leading to the cylinder of the diesel engine.

  In the connecting pipe between the suction chamber and the pump piston supply, the above-mentioned safety valve (ELAB) is arranged which interrupts the supply of fuel from the suction chamber to the piston of the pump. the pump, when certain safety conditions are exceeded. In this case, however, there is the problem that the ELAB and all other components considered, is part of the fuel metering device and stops the engine when its operation is controlled separately. This therefore excludes the possibility of checking by a test on its ability to operate, the ELAB for example controlled in time, that is to say at predetermined time intervals in normal operation of the motor vehicle, and this for reasons of safe operation because this control could

result in a motor stop.

  On the other hand, a fault on the ELAB may not be detected by the driver, because when the power supply is cut off, not only is the ELAB possibly defective deprived of power, but also the power supply in tension

2641327 7

  for the fuel quantity control system

  and the other components, is cut off.

  The purpose of the invention is therefore to transfer the control of the ELAB to the station where the maintenance is carried out, in any case, and to take in this station the provisions which guarantee that this control is also included. specifically in the works

  maintenance and is performed by the specialist fitter.

  For this purpose, the invention provides a method characterized in that in the maintenance station, and while the engine is running, the control step "ELAB control" is called when a maintenance staff presses the key. diagnosis, and that, by pressing this diagnostic key for a longer preset period of time (T> TO), or by a short key operation, with a hold function triggered automatically afterwards, the ELAB is excited and stopping the engine is interpreted as an indication of the correct functioning of the organ

safety stop ELAB.

  The invention also provides, for the implementation of the method, a device characterized in that there is provided a diagnostic key to be operated by the maintenance personnel in the maintenance station, key through which, l step of

  control "ELAB control" is realized.

  The method according to the invention, or the device according to the invention, having the characteristics indicated above, make it possible to achieve the object of the invention and have the advantage that for the control in the station of maintenance, no additional equipment is required in practice, and that the test step for the operation of the ELAB can be placed at the end of the diagnostic process, stopping the engine

  then taking place via ELAB.

  Thanks to this deliberate execution of the control step of the ELAB during diagnosis in the vehicle maintenance station, a definite relationship is established between the control of the ELAB in the course of the test (action) and the reaction that is necessarily expected from the internal combustion engine (reaction). As, moreover, an interrogation with regard to a constant rotational speed during no-load operation is simultaneously possible, it results in an increase in availability. Moreover, it is certain that the realization of the "ELAB test" step does not take place unintentionally. The diagnostic request link must, in order to trigger the ELAB test, receive a preset voltage, for example the supply voltage of 12 volts. A sustained short circuit of the diagnostic link can therefore cause the ELAB not to react. In addition, this defect may be identified

  later during subsequent maintenance operations.

  Another advantage lies in the fact that the possibility of an unintentional interruption of the actuation of the diagnostic key, thanks to which the test function of the ELAB is performed, does not necessarily lead to an interpretation. wrong, because the running of the test function can be carried out in the software part, for example of the control device, so that the control step of the ELAB can be released by the maintenance personnel. as the last fault to control for the realization, and then, when the manual operation expected of the corresponding diagnostic key, this control step is, after its external initialization, also maintained automatically and can be performed until stopping (waiting) the engine by a corresponding program sequence in the control unit, regardless of whether the service person interrupts the operation of the key. The reason why, in this case, it is necessary to allow a certain amount of time to lapse is that, after the reaction of the ELAB, a predefined period of time elapses until fuel is drawn into the area of the injection pump in such a way that the motor then stops by lack of fuel (when the ELAB safety shut-off valve is closed). A period of time between 20 and 30 seconds, up to approximately 1 minute maximum, must be applied in this case for the duration

the button is pressed.

  In this way, the control of the ELAB can be transferred to the maintenance station and to ensure a correct operation of the test function. This is advantageous, because in case of ELAB defect, we should, anyway

call for service.

  Advantageous additions and improvements of the invention are possible in that, according to another characteristic of the invention, the method is characterized in that, when a diagnostic interface exists, the diagnostic procedure is expanded by the introduction of another control step concerning the control function of the ELAB, so that by actuation of the diagnostic key, after calling the control step "ELAB check", the defectiveness of the ELAB can be observed in the course of the diagnosis over a longer period of time and the judgment of the

engine following.

  According to another characteristic of the invention, the device is characterized in that by actuating the diagnostic key while the engine is running, the ELAB is controlled with a defined supply voltage to interrupt the power supply.

in fuel.

  An exemplary embodiment of the invention is shown in the accompanying drawings and will be shown

  in more detail in the description below.

  FIG. 1 schematizes, in the form of block diagrams, the basic constitution of the control unit of the diesel electronic control system, in its part of interest for the present invention, and it also shows its association with the system. setting the amount of

fuel, -

  FIG. 2 shows, in the form of a functional diagram, a sub-program for carrying out the test function of ELAB by

  actuation of a diagnostic key.

  To allow a better understanding, a simple embodiment, with respect to the material part, is shown in the drawing. But attention is drawn to the fact that the discrete switching stages shown in the drawing, do not limit the invention, but serve only to illustrate the basic functional effect of the invention and to indicate the special functional sequences in its possible form of realization (Hardware). It goes without saying that the different building blocks can be made using an analog technique, digital or also using a hybrid technique, or that they can also, preferably, be assembled totally or partially, they can include appropriate parts digital systems controlled by programs, for example microprocessors, microcomputers, digital or analog circuits, etc., which can, in particular, also be deposited under

  form of stored program sequences.

  The control apparatus of the EDC system is designated 10, the fuel quantity control system (pump), controlled by the control apparatus 10, is designated 11. The control apparatus 10 receives indications of as regards the rotational speed n from a rotational speed indicator 12, indications as regards the position of the accelerator pedal, from the accelerator pedal position indicator 13, and where desired, an indication of brake actuation (brake indicator), start-up information, and fuel temperature information supplied to the injection pump, together with signaling signals from the engine. other detectors, which need not be clarified here, for example with regard to the cooling water, the battery voltage. The control unit 10 controls, via a terminal stage indicated diagrammatically 10a, the adjustment system 14 of the magnet in the fuel injection pump of the fuel quantity adjustment system 11, a Position repeater 15 being further indicated. The electromagnetic safety shut-off valve ELAB associated with the fuel quantity control system, or the fuel injection pump, is designated 16 and is controlled via a control link 16a, also by the control device 10, for example as shown in the drawing, via an OR member 17, to which are applied, from a safety logic circuit 19 inside the 10, signals causing the ELAB to switch off (corresponding to the interruption of the fuel supply), these signals being able to result from a plurality of operating states detected by the

safety logic circuit.

  In contrast to this, the control of the ELAB is effected via an additional test function based on the present invention, this function being based on the fact that a control of the ELAB is carried out as a maintenance service, the vehicle preferably having a diagnostic interface (but this is not a necessary precondition), which is then used so that during maintenance in the service In the case of maintenance, an engine stop via the ELAB is carried out in an additional test step, the ELAB being suitably controlled by means of a diagnostic button. For this purpose, no additional equipment is required, as this test step may be included in the output of the

fault diagnosis.

  In the simplest case, it is then, for vehicles that have the aforementioned diagnostic interface, the call of the test step by a first actuation of the diagnostic key, in which case, an output of normal defect having previously occurred with the engine stopped or running, is not necessary for the

the test function of ELAB.

  It then follows, through the diagnostic device, the invitation to perform the step "control ELAB". For this purpose, it is necessary: 1. to start the engine 2. to activate the diagnostic button for a longer time, for example 20 to 30 seconds, and at most 1 minute, when the engine does not stop 3. if the engine also does not stop after this period of time, so if this has not happened after about 1 minute, the ELAB or the ELAB control is then defective. This is the basic procedure which, as it is conceived, must also be carried out for vehicles that do not have a diagnostic interface. In this case, a diagnostic key 20 for the "ELAB control" function can be provided at a suitable location, for example in the engine compartment, this key being pressed by the maintenance personnel during a period of time. longer time, either during the call of the "ELAB control" step, or during the normal course of maintenance operations, and this until the engine stops. If within the period of time indicated above, the engine does not stop, it should be concluded that there is a fault in the ELAB or its control, its diagnostic key 20 applying, in this case (ie without diagnostic interface) to ELAB 16 an appropriate control voltage via the OR element 17,

  as indicated by the arrow 18.

  If there is provided a diagnostic interface which is schematically shown and designated 21 in FIG. 1, the diagnostic key 20 is a natural part of the diagnostic device and the maintenance staff is working in the usual way, in which case at the same time. During the diagnosis, the "ELAB control" step is also called as one of the control steps by pressing the diagnostic key, and the progress of the control step is then carried out as previously mentioned. . It is then possible to carry out the control step by incorporating control of the test function of the ELAB as a routine into a test program, during diagnosis at the maintenance service, in which case the The computer for the diagnosis, including the performance of the ELAB test function, may be provided at any location, also in the control unit 10, in the diagnostic apparatus, or at

another location.

  The functional diagram shown in FIG. 2 shows one of the possibilities allowing the maintenance personnel, during the diagnosis in the maintenance department, to let the control step of the ELAB proceed by pressing the

diagnosis (external manipulation).

  In this case of the deliberate performance of the inspection step by the maintenance personnel, the maintenance staff is asked, in a manner appropriate, to carry out the ELAB control step. This is done by a (new) depression of the diagnostic key, which is only of short duration, because the program can ensure an appropriate "hold" of the ELAB control signal, in which case, after the flow of a maximum time (T> TO) the result is then obtained, namely that if the engine is stopped, the ELAB is in order, or despite the control of the ELAB function through the actuation of the diagnostic key, the motor

continues to turn.

  All the features described or

  represented in the description, the claims

  Hereinafter and the drawings, may be considered important for the invention whether considered individually or in any combination.

Claims (4)

  1. A method for controlling a safety shutdown device (redundant) in the form of an electromagnetic shut-off valve (ELAB) in internal combustion engines, especially diesel engines, whose control system the quantity of fuel is controlled by a diesel electronic control unit (EDC), the supply of fuel to the engine being interrupted by the safety shutoff device when a fault occurs, characterized in that in the maintenance station, and while the engine is running, the check step "ELAB check" is called when a maintenance person presses the diagnostic key, and that by pressing this diagnostic key for a period of time longer preset time (T> TO), or by short-time operation of the key with a hold function automatically triggered afterwards, the ELAB is energized and the motor stop is interpreted as an indication. noting the correct operation of the ELAB safety shut-off device. 2. A method according to claim 1, characterized in that, when there is a diagnostic interface, the diagnostic process is expanded by the introduction of another control step concerning the control function of the ELAB, of by pressing the diagnostics key, after calling the check step, "ELAB check", the malfunction of the ELAB can be detected in the diagnostic flow over a longer period of time and the shutdown of the engine following it.  3. Device for controlling a safety shutdown device (redundant) in the form of an electromagnetic shut-off valve (ELAB) in internal combustion engines, especially diesel engines, including the quantity control system of fuel is solicited by a diesel electronic control (EDC), the safety stop device interrupting the fuel supply of the engine when disturbances or defects appear, device provided for the implementation   method according to any of claims 1   or 2, characterized in that there is provided a diagnosis key to be operated by the maintenance personnel in the maintenance station, key through which the control step "ELAB check" is performed. 4.- Device according to claim 3, characterized in that by actuating the diagnostic key, while the engine is running, the ELAB is controlled with a supply voltage defined for   stop the fuel supply.