FR2755185A1 - DEVICE FOR CONTROLLING THE OPERATION OF A DIESEL ENGINE IN PARTICULAR OF A MOTOR VEHICLE - Google Patents

Abstract

This device for controlling the operation of a diesel engine, in particular of a motor vehicle, is characterized in that it comprises: - means (2, 5, 6, 7, 8) for recording the amplitude of the vibrations of the engine during certain phases of its operating cycle, - means (9, 10) for establishing characteristic information (IC) of engine operation, by dividing the amplitude of these vibrations by a reference value, and - means (11, 12, 13) for analyzing this characteristic information (IC) of the operation of the engine in order to determine therefrom information for checking the operation of the latter.

Description

The present invention relates to a device for controlling the operation

a diesel engine, in particular

of a motor vehicle.

  It is known that the torque that a diesel engine provides depends mainly on the amount of fuel that is injected into it. However, a bad

  control of this quantity injected or the moment to

  which it is injected, can seriously damage the engine. Such a defect can be caused for example by a leaky injector on a single cylinder of the engine, which is particularly difficult to detect by the system.

injection management.

  In particular, it has developed in the state of the art, an injection system for diesel engine by injectors common supply, called "COMMON RAIL", with which the different injectors of the engine are

  powered by a constant fuel pressure.

  However, in such a system, it is extremely

  it is difficult to detect any defect in

  example of an injector, which may

  relatively large engine damage,

even the case of it.

  The object of the invention is therefore to solve these problems by proposing a device for controlling the operation of a diesel engine, particularly a motor vehicle, which is simple and reliable and which makes it possible, for example, to detect an injector fault with a reaction time adapted to the severity of this defect for the

engine.

  For this purpose, the subject of the invention is a

  control system for the operation of a diesel engine, especially a motor vehicle, characterized in that it comprises:

  means for measuring the amplitude of the vibra-

  the engine during certain phases of its operating cycle, means for establishing a characteristic information of the operation of the engine, by dividing the amplitude of these vibrations by a reference value, and this characteristic information of the operation of the engine to determine a function control information

of it.

  Advantageously, the survey means comprise

  nent: - a vibration sensor of the engine, - means for processing the output signal of this sensor,

  - means of establishing temporary windows

  of the amplitude of vibrations, corresponding to

  coupling said operating phases of the engine and referenced on its operating cycle, - recognition means for each survey time window, the corresponding cylinder of the engine, and means for correcting the amplitude of the vibrations recorded to take account of the distance

separating the cylinders from the sensor.

  The invention will be better understood when reading

  the following description, given solely for the purpose of

  for example, and with reference to the accompanying drawings, in which: - Figure 1 shows a block diagram illustrating the general structure of a control device according to the invention - Figure 2 shows a block diagram

  illustrating the different ways in which the

  such a device, and - Figures 3, 4 and 5 represent different graphs illustrating the determination of a protection curve of an engine, used in a control device.

control according to the invention.

  1 is shown in FIG.

  the structure of a function control device.

  a diesel engine, particularly a motor vehicle. In this figure, the diesel engine is designated

  by the general reference 1 and the device according to

  vention comprises a vibration sensor, designated by the general reference 2, implanted in any place

  of the vehicle engine, to measure the amplitude of the vibra-

  during its operation.

  The output of this sensor is connected to a unit

  of information processing consisting of any calculation

  appropriate carrier, designated for example by the general reference 3 and associated with data storage means designated by the general reference 4, which will be described

in more detail later.

  As will be described in more detail later, these different means make it possible to analyze

  the operation of the engine to determine an information

  control of the operation of it.

  It should be noted that the information processing unit

  3 and the data storage means 4 may for example be integrated in a control computer

  the main function of the engine or in a calculation

  dedicated to this function.

  The vibration sensor designated by the reference

  2 can, for its part, be a conventional type of sensor enabling the vibrations of the

  motor and constituted, for example, by an acceleration sensor

  rométrie. We have illustrated in Figure 2, the different

  means for processing the output signal of such a sensor.

  In this figure 2, the sensor is always

  designated by the general reference 2 and the exit of that

  it is connected to signal processing means,

  designated by general reference 5.

  These processing means comprise, for example, amplification, filtering,

  rectification and / or integration, of conventional type.

  The output of these processing means 5 is connected to means designated by the general reference 6, making it possible to establish time windows for recording the amplitude of the vibrations, corresponding to certain phases of operation of the motor and referenced on its

operating cycle.

  Indeed, these means make it possible to note, for certain operating ranges of each cylinder of the

  motor, the amplitude of the corresponding vibrations.

  These vibrations may, for example, be rele-

  in a range extending from x degrees to the top dead center (TDC) or to the corresponding top dead center

of this cylinder.

  This increases the sensitivity of the arrangement

  by increasing the signal-to-noise ratio by sampling. As shown in Figure 2, it

  in this scheme, means are also

  by general reference 7, allowing recognition of

  for each measurement time window, the corresponding cylinder of the engine, these means 7 receiving at the input, for example, information of speed and load of

engine operation.

  The output of these recognition means 7 is connected, on the one hand, to means 8 for correcting the amplitude of the vibrations recorded to take into account the distance separating each cylinder from the sensor, these means 8 also receiving the output of the means 6 and on the other hand, computing means designated by the general reference 9, which will be described

more in detail later.

  The correction means 8 make it possible to compensate

  the signal level dispersions between cylinders, related to their different distances from the sensor, a gain correction being applied specifically to the amplitude of the vibrations of each cylinder of the engine

by these correction means.

  The output of these correction means 8 is connected to the calculation means 9 mentioned above but also to means for setting values of

  reference, designated by reference numeral 10 in this figure.

  In fact, the calculation means 9 are adapted

  to establish a characteristic information IC of the function

  the motor, dividing the amplitude of the vibra-

  associated with each cylinder of the engine by a reference value also associated with each cylinder thereof. In the exemplary embodiment described in this figure, the reference value associated with each cylinder of the engine, is delivered by the means 10 which allow

  calculate the lowest moving average of the ampli-

  study of the vibrations recorded for each cylinder, during

  previous cycles of engine operation.

  It is then conceivable that, at the output of the calculation means 9, there is available a characteristic information IC of the operation of the engine associated with each cylinder and

  obtained by dividing the amplitude of the vibrations corres-

  by a corresponding reference value.

  This characteristic information of the functioning

  the engine is then transmitted to test equipment.

  lysis designated by the general reference 11 in this figure, to determine a control information of the operation of the engine. In particular, these means of analysis include

  comparison means designated by the general reference

  12, receiving as input the characteristic information IC of the operation of the engine and the operating speed and load information thereof, these means 12 being adapted to compare the characteristic information IC with a safety threshold which will be

  described in more detail later, and in the event of

  read the maximum permitted number of revolutions of the engine in corresponding data storage means

  constituted, for example, by the storage means

  given by the general reference 4 in FIG.

  These comparison means 12 then deliver two pieces of information to control means designated by the general reference 13 in this figure, namely a safety threshold overrun information and a maximum allowable revolution number information of the engine, to allow these means 13 for controlling a cut of at least the corresponding cylinder of the engine, when the characteristic information always exceeds the safety threshold and the maximum permissible engine speed is reached, in order to avoid any degradation thereof . It is then conceivable that the analysis means process two pieces of information, namely an exceeding of the safety threshold on a cylinder being analyzed and the maximum permissible number of revolutions of the engine to determine whether or not a cut in this cylinder or possibly the engine. The safety threshold and the maximum permissible number of revolutions of the motor can, as indicated above, be stored in data storage means which comprise, for different speeds and operating loads of the engine, a protection curve of that it is possible to determine the maximum permissible engine revolutions according to the characteristic information of the engine operation and established on the basis of a predetermined breakage curve of the engine.

  motor, as illustrated in Figures 3 to 5.

  Indeed, it is possible, as illustrated in FIG. 3, to establish and report on a graph, a zone of engine failure by monitoring PTM parameters directly representative of the engine behavior, such as,

  for example, pressure and temperature.

  From this engine break zone, it is possible, for a given speed and load, to establish an acceptable operating characteristic signal such as that illustrated in FIG. 4, taking a certain margin of safety with respect to the break zone. of

  engine. It can be seen that, beyond the illus-

  in this figure 4, the risks of engine failure

are not acceptable.

  From this engine crash limit curve, it is possible to establish a protection curve of the engine, as shown in Figure 5, this protection curve representing the maximum permissible engine speed in use. some information

  IC characteristic of the operation thereof.

  The security threshold may correspond to the

  horizontal symptom of this protection curve as

this is illustrated.

  In fact, these different information are

  established following engine tests during the development

  of the latter, these tests making it possible to determine the limits of the engine with respect to the signal level

from the vibration sensor.

  It is conceivable then that the device according to

  The invention has a number of advantages insofar as it ensures an optimal and immediate protection of the cylinder or the motor, in the event of a malfunction, for example of the injection system.

  this one, with a reduced level of false detection.

  tions. Of course, different embodiments of

  this device can be envisaged.

Claims (7)

  1. Device for controlling the operation of a   diesel engine, in particular of a motor vehicle,   characterized in that it includes: - means (2, 5, 6, 7, 8) for measuring the amplitude of the vibrations of the engine during certain phases of its operating cycle, - means (9, 10) establishing a characteristic information (IC) of the operation of the engine, by dividing the amplitude of these vibrations by a reference value, and - means (11, 12, 13) for analyzing this characteristic information (IC ) of the operation of the engine, to determine a control information of the operation of it.   2. Control device according to claim 1, characterized in that the reading means comprise: a sensor (2) of vibrations of the engine, means (5) for processing the output signal of this sensor, (6) establishment of time windows for recording the amplitude of the vibrations, corresponding to said phases of operation of the engine and referenced on its operating cycle, means (7) for recognizing for each time window of reading, the corresponding cylinder of the motor, and - means (8) for correcting the amplitude of the vibrations recorded to take account of the distance separating the cylinders from the sensor.   3. Control device according to claim 1 or 2, characterized in that the reference value is delivered by calculation means (10) of the lowest sliding average of the amplitude of the vibrations recorded.   for each cylinder, in previous cycles of operation engine.   4. Control device according to any one   of the preceding claims, characterized in that the   means (11) for analyzing the characteristic information (IC) of the operation of the engine receive information on the speed and operating load of the engine and comprise means (12) for comparison, for the   given regime and load, information characteris-   that (IC) of the operation of the engine with a safety threshold for, in case of exceeding, read a maximum number of laps allowed of the engine in corresponding data storage means (4) and means (13) of cut-off at least the corresponding cylinder of the engine,   when the characteristic information (IC) always exceeds   days the security threshold and that the number of rounds   maximum allowed motor is reached.   5. Control device according to claim 4, characterized in that the breaking means (13) are adapted to cut the motor 6. Control device according to claim 4 or 5, characterized in that the data storage means (4) comprise, for different modes and   engine operating loads, a protection curve,   the engine, to determine the number of   maximum permitted engine revolutions according to the information   characteristic of the operation of the latter and established on the basis of a predetermined curve of   engine obtained by engine tests.   7. Control device according to claim 6, characterized in that the safety threshold corresponds to   to the horizontal asymptote of the protection curve.