FR2630501A1 - METHOD AND DEVICE FOR CONTROLLING THE FUEL SUPPLY FOR AN INTERNAL COMBUSTION ENGINE INVOLVING A VEHICLE - Google Patents

Abstract

The invention relates to a method and a device for controlling the supply of fuel for an internal combustion engine driving a vehicle, wherein the amount of fuel is limited in higher load ranges. In order that the emission of harmful substances is kept as low as possible while still allowing maximum power to be reached when the resistance is increased during operation, the limitation of the quantity of fuel injected is gradually removed below a predetermined limit value aG for the acceleration of the vehicle, this value being obtained, as a function of the running speed v of the vehicle and of the rotational speed n of the engine, from a family of characteristic curves 26.

Description

The present invention relates to a method for controlling the supply of

  fuel for an internal combustion engine driving a vehicle, wherein the amount of fuel is limited in higher load ranges. According to the German patent application DE-OS 36 38 474, it is known a method of the aforementioned type, according to which a measuring device placed in the exhaust pipe of the engine transmits a signal corresponding to the degree of harmfulness of the exhaust gases. exhaust to an electronic control unit by which, when the engine is operating at full load, the quantity of fuel to be injected is limited so that a predetermined limit value for the ejection of soot particles is not exceeded, while that simultaneously we have

  always of an optimal capacity of power.

  So that the harmfulness of the exhaust gases can not also reach an excessive value during unstable operation of the engine, it has been proposed in the German patent application DE-OS 32 04 804 to take into account, when selecting the minimum value for fuel injection, among other things also of the variation

  the speed of rotation of the motor over time.

  Both methods, however, have the disadvantage that in the case. of an increase of the resistance in progress to be overcome, as for example during strong uphill of the road, the engine can not reach the maximum power which it would be possible to obtain without a limitation of the quantity

injection at full load.

  The object of the invention is therefore to improve a process of the type defined in the first paragraph, by means of which the emission of harmful substances can be kept as low as possible but, however, when an increase in resistance is obtained. the engine can still

reach its maximum power.

  The aforementioned problem is solved according to the invention in that the limitation of the fuel quantity is suppressed below a value

  predetermined limit for acceleration of the vehicle.

  The method according to the invention provides that, during the normal operation of the vehicle, there is constantly a limitation of the amount of fuel in the field of full speed, which allows to minimize the emission of substances

  harmful substances which increase precisely in a suprapropor

  for high loads. However, when, due to an increase in resistance during operation, for example in climbs or in the case of heavy loads, even in case of full speed operation, the power supplied by the engine is no longer sufficient, this limitation of the quantity of fuel is suppressed. The driver does not, however, have any influence on this deletion because it is controlled exclusively according to the acceleration. In this way, an intentional release of the maximum amount of fuel with low resistance to gait is excluded, that is, when sufficient power is available even when

  a limitation of the quantity at full speed.

  The permanent limitation of the power of the engine at full speed in a normal operating condition leads, during a start-up process and because of a decrease in the start-up slip,

  precisely to a decrease in tire wear.

  At the same time, when starting at full speed, we obtain an improvement in walking comfort because the maximum power, now reduced, inevitably also causes a decrease in jolts

  acceleration when starting from the stop.

  Of course, fuel economy is also achieved by limiting the amount to full speed. According to another particularity of the process

  according to the invention, the limit value for accelerating

  vehicle is determined according to the speed of the vehicle and the speed of rotation

  the engine from a family of characteristic curves.

  c; this gives an optimal adaptation of the

  their acceleration limit, determining the suppression of the power limitation, the running speed of the vehicle at each given moment and the speed

  rotation of the engine at the given moment.

  The method according to the invention is implemented by means of a device comprising an electronic control unit, which receives a signal corresponding to the predetermination of the charge at each given instant and which produces a control value signal. for actuating an adjusting device

  determining the amount of fuel supply.

  According to the particularities of this device: the control unit also receives, for determining the acceleration of the vehicle at each given instant, a signal corresponding to the speed

  of the vehicle at the given moment, or a signal corresponding to

  spanning at the speed of rotation of the engine at the moment

  given; a family of characteristic curves, func-

  the speed of the vehicle and the speed of rotation of the engine is recorded in a memory of fixed values of the control unit in order to determine the corresponding limit value of the acceleration of the vehicle; and the adjusting value signal controls the adjusting device such that, for the full load of the engine and for a vehicle acceleration which is less than the limit value determined respectively from the family of characteristic curves, the maximum quantity

  fuel is supplied to the engine.

  - The electronic control unit is connected, by means of an electrical signal transmission conductor to a contactor actuated by depressing the accelerator pedal fully, to the downshift contactor, which can

  be operated from the accelerator pedal.

  - The signal corresponding to the speed of the vehicle at the given moment is captured by means of a sensor mounted on a wheel of the vehicle and is transmitted, via a transmission cable of measured values to the vehicle. electronic unit

control.

  Other features and advantages of the invention will be highlighted, in the following

  of the description, given by way of nonlimiting example

  with reference to the accompanying drawings in which: Figure 1 shows a block diagram of an embodiment of a device for implementing the method according to the invention and Figure 2 shows the mode of operation of the unit control unit designated 10 in Figure 1. Figure 1 shows a diesel engine 1 driving a vehicle not shown; on the engine is provided an injection pump 2 driven by

  him and having a speed regulator 3.

  On the speed regulator 3, there is provided an actuating lever 4, which is connected via a linkage 5 to a pedal

  accelerator 6 can be actuated by the driver.

  To simplify the drawing, this linkage 5 has

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  not been completely represented. The degree of charge of the engine, selected by the driver, is transmitted via the accelerator pedal 6

  that is, via the actuating lever 4.

  For this purpose, in a known manner, taking into account the rotational speed n of the engine, a regulating rod 7, mounted on the injection pump 2 and whose position represents a measurement of the amount of injection of fuel, is moved between a minimum position and a stop position at full speed A or B. A possible displacement only to the stop position & full speed A, that is to say a limitation of the injection amount at full speed, is provided according to the invention in normal operation while a movement into the position B shown in broken lines is possible when the vehicle must overcome an increase in resistance to walking. The determination of the resistance of walking

  to overcome is effected by means of accelerating

  each vehicle at each point in the full market. For this purpose, there is provided on the throttle pedal stop a contactor actuated by depression of this pedal at the bottom, that is to say what is called a contacteurderétrogradation 8, which transmits its position, by the intermediate of a measurement value transmission conductor 9, to an electronic control unit 10. This control unit 10 further receives, via a sensor 11 and a driver 12 for transmitting values of measuring, a signal representing the rotational speed of a driving wheel 13, and therefore also a signal corresponding to the running speed v of the vehicle, and through the sensor 14 and the transmission of measurement values, a signal representing the current speed of rotation n of the

  engine. Depending on the signals applied to it.

  the control unit 10 produces a setting value signal which controls via the conductor 16 an adjusting device 17 installed on the injection pump 2 for the purpose of moving the stopper at full speed between the position A ( quantity limited at full speed) and the B position (maximum amount at full speed) in the manner highlighted on

Figure 2.

  The control is engaged when starting the engine (Figure 2). In the input block 18 is carried the transmission of the position of the derogating contactor 8 at the given time. When it is not actuated (bypass block 19), no full speed facility is made from the pedal of accelerator 6 so the function

  order is returned to its starting point 20.

  In the case where the downshift switch 8 is not actuated, the full thrust stop of the control rod 7 is always in the position A limiting the amount of fuel injection. When a full-power condition exists (bypass block

  19), the following block 21

  acceleration of the vehicle at the given moment. This is achieved by means of a clock integrated in the control unit 10 and ensuring that respectively always at the beginning and at the end of a predetermined time interval Tm, the speed v of the vehicle at this instantrespectif is read (block 22 and bypass block 23) and is stored (block 24). By establishing the difference between these two speeds vm and vm_1 and dividing by the time interval Tm, the acceleration a of the vehicle (block 24) is obtained at the given instant. After the determination of the value a, it is determined in the block 25, from a family of characteristic curves 26 recorded in a memory of fixed values of the control unit 10, and also as a function of the speed v of the vehicle at the given instant and the speed of rotation n of the engine at the given instant, which was also defined beforehand in the block 22, a limit value aG for the acceleration of the vehicle, limit value below which the limitation of the injection quantity at full speed is eliminated. Obviously, the corresponding limit value aG can also be calculated from a predetermined function in relation to the aforementioned parameters. In the shunt block 27, there is now a query to determine whether the acceleration a of the vehicle at the given instant is greater than or equal to the limit value aG. If not, that is, when the acceleration a of the vehicle is less than the limit value aG because of an increase in the resistance to the gait, it occurs through the output block

  28, a corresponding command of the operating device

  17, so that the stop full speed is transferred to the position B, that is to say in the position allowing the maximum amount of fuel injection. The full speed stop remains in this position B as long as there is a negative answer to the question of whether the downshift switch 8 is still actuated (input block 29 and bypass block 30) or, in the case where the downshift switch is closed, up to

  What is established is an acceleration that is superior to

  re or equal to the limit value aG (block 27). When the downshift switch 8 is open (block 30), the control function is transferred directly to the point 31 and then the actuating device 17 passes the full thrust stop back to the position A, that is to say say in the position determining the quantity at full speed (output block

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  32. When the downshift switch 8 is still closed (block 30), it occurs initially, to be able to constantly obtain the acceleration

  a (block 21) at each given instant, a return to the block of

  22 for a new introduction of v and n. When the acceleration a of the vehicle at the given moment is greater than or equal to the limit value aG (bypass block 27), the full speed stop remains in position A or else it is transferred to this position A in the case o it was still in position B. Then there is a return to the starting point 20 for a new introduction of

  the state of the downshift contactor 8 at each given instant.

  Since the limit value aG is determined both as a function of the vehicle running speed or the speed of rotation of the wheels and the speed of rotation of the motor, the corresponding transmission ratio of the gearbox is automatically taken into account. of speed for the determination of the limit value because the ratio between the speed of rotation of the wheels and the speed of rotation of the engine provides a direct indication of the transmission ratio precisely adopted. Instead of sensing the speed of rotation n of the motor (block 22, FIG. 2), it is obviously possible in this respect to transmit 'directly

  to the control unit the transmission ratio specified-

  selected by means of an appropriate measuring sensor which is installed on the selector lever or

  shifting of the vehicle.

  According to another particularity of the invention, one can also consider successively determining several acceleration values at given times for

  deduce the average value and to order in correspon-

  the actuator 17 (Figure 1).

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  It is then possible to prevent for example an immediate and undesirable reaction of the actuating device to a measurement value accidentally leaving the

measurement tolerances.

  The control also provides that, in the event of failure of a measuring sensor, the injection quantity at full speed is constantly limited until

  restoration of the correct functioning of this sensor.

  This ensures an emergency march with little emission of harmful substances. The failure of a sensor can be signaled via a

  pilot lamp installed on the dashboard of the vehicle.

  The invention is not limited exclusively to a suppression of the power limitation under full power conditions, but it is also

  possible to remove the power limitation when

  a predetermined limit value is reached in the full speed condition. In this respect, it is possible to use, in place of a downshift switch, also a suitable sensor which detects the travel of the accelerator pedal or the operating lever and whose measurement signals are applied to the control unit, which finally ensures, when the predetermined limit value is reached in the load range envisaged, the removal of the limitation of the fuel injection amount. Naturally, in this case, it is naturally also possible to suppress the power limitation only when a corresponding limit value of the acceleration of the vehicle has already been reached.

exceeded by default.

  To obtain an additional improvement in walking comfort, it is also conceivable to provide for a gradual limitation of the injection quantity at full speed by making sure that the maximum speed stop can take, depending on the operating condition, any position between the positions A and B. In the case where there is provided on each wheel of the vehicle a sensor detecting its speed of rotation, the method according to the invention can be

  used without significant increase in the cost of adapting

  control also for regulation

from skating to training.

  Of course, the present invention is not limited to the embodiments described and shown; it is capable of numerous variants accessible to those skilled in the art, depending on the applications envisaged and without departing from

his mind.

he

Claims (5)

  A method of controlling the supply of fuel for an internal combustion engine driving a vehicle, wherein the fuel quantity is limited in higher load ranges, characterized in that the limitation of the fuel quantity is suppressed below a predetermined limit value (aG) for acceleration of the vehicle.   2. Method according to claim 1, characterized in that the limit value (aG) for the acceleration of the vehicle is determined as a function of the running speed (v) of the vehicle and the speed of rotation (n) of the engine. partir.d'une   family of characteristic curves (26).   3. Device for implementation   method according to one of claims 1 and 2, comprising   an electronic control unit, which receives a signal corresponding to the prediction of the charge at each given instant and which produces a setting value signal for the actuation of an adjusting device determining the fuel supply amount, characterized in the control unit (10) furthermore receives, for determining the acceleration (a) of the vehicle at each given instant, a signal corresponding to the speed (v) of the vehicle at the given moment or a   signal corresponding to the speed of rotation (n) of the   at the given moment, in that a family of characteristic curves   the speed of the vehicle and the rotational speed of the motor, is stored in a memory of fixed values of the control unit (10) in order to determine the corresponding limit value ( aG) of the acceleration of the vehicle, and in that the adjustment value signal controls the adjusting device (17) so that for full load of the engine (1) and for acceleration of the vehicle (a) which is less than the limit value (aG) respectively determined from the family of characteristic curves (26); the maximum amount of fuel is provided to the engine.   Device according to Claim 3, characterized in that the electronic control unit (10) is connected by means of an electrical signal transmission conductor (9) to a downshift contactor (8) which can be actuated   from the accelerator pedal (6).   5. Device according to one of the claims   3 and 4, characterized in that the signal corresponding to the speed (vi of the vehicle at the given moment is captured by means of a sensor (11) mounted on a wheel (13) of the vehicle and is transmitted by via a driver (12) for transmitting   measurement, to the electronic control unit (10).