FR2487916A1 - ELECTRONICALLY CONTROLLED FUEL INJECTION PLANT WITH VARIABLE REGULATOR FEATURE - Google Patents

Abstract

THIS ELECTRONICALLY CONTROLLED FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES IS DESIGNED SO THAT THE INJECTION DURATIONS ARE VARIABLE IN ORDER TO PROPORTION THE QUANTITY INJECTED. THE CIRCUIT FOR THE FORMATION OF THE VOLTAGE VARIATION OF INJECTED QUANTITY 300 INCLUDES A COMPARATOR DEVICE 330, A BISTABLE SWITCHING DEVICE 326, A GATE 324 FOR THE PULSES FROM THE PULSE GENERATOR DISK, AND A COMPONENT FOR THE FORMATION OF THE VARIATION OF VOLTAGE OF DECREASING QUANTITY OF ADJUSTMENT 327, WHICH CAN BE SWITCHED BY THE BISTABLE SWITCHING DEVICE 326 AND TO THE INPUT 327E1) TO WHICH IS CONNECTED THE OUTPUT 322A OF THE COMPONENT 322, WHILE THE INPUT 50E OF THE ANALOGUE MEMORY IS ITS 327A OUTPUT.

Description

The invention relates to a car injection installation

  electronically controlled burant for internal combustion engines

  ne, installation in which the duration of the injection is variable in order to proportion the quantity injected and in which it is planned, to place the appropriate pulses which control the injection in coincidence with the position of the crankshaft of the internal combustion engine, the following electronic components: Circuits to form respectively - an injection range pulse, - a voltage which decreases in the injection range according to the angle of rotation of the crankshaft, - a quantity voltage injected according to the signals

  input device and the rotation speed of the city

  brequin in a constant measurement period, determined by a measurement time generator triggered by the trailing edge of the injection range pulse, a component being provided

  to form a voltage variation from a number of im-

  pulses detected in a time interval from a pulse generator disc on the crankshaft,

- a reference voltage.

  In addition, there is mounted, following the circuit forming the quantity injected voltage, an analog memory which is also controlled by the measurement time generator and

  which retains the amount injected voltage.

  In a comparator device, to which are connected directly or indirectly,. input side, the outputs of

  circuits forming the voltage which decreases in the injection range

  tion, the quantity injected voltage and the reference voltage, and at the output of which the injection duration pulse is available, the injection pulse is assigned to the instantaneous position of the crankshaft of the engine

internal combustion.

  Already known from the German Democratic Patent ng 126,609, an electronic injection system of the kind defined in the preamble. Its basic structure is shown in fig. 1 illustrating the embodiment of this document. Fig. 2 of the cited patent is the corresponding block diagram. In the case of this injection installation, the voltage of quantity injected is formed by multiplication from a voltage proportional to the speed of rotation and corrected and from a voltage proportional to the load and, consequently, it is called voltage-product. We obtain

  the regulation characteristic of a two-stage regulator.

  On the other hand, we already know in principle, from German Democratic Patent No. 120 508, how to obtain,

  in injection systems, the position of the angle of

  jection by the comparison of an injected quantity voltage and an injection angle voltage. Under these conditions, we also know how, by additive logic côiabiảison of correction and displacement voltages with the voltage of quantity injected - in this case a product-tension - and / or with the reference voltage, obtain a displacement of l 'injection angle or take into account time constants,

  for example the response time for ordering injectors.

  From the basic structure of an information installation

  jection of the genre defined in the preamble, the purpose of the invention

  tion is to achieve a variable regulator characteristic

corn.

  By modifying the circuit, we have solved the problem.

  consisting of me, in an injection facility of the kind

  defined in the preamble, to obtain the functional characteristic

  operation of a variable regulator. By means of a device

  input, a working speed of the motor is selected beforehand

  lable and, in case of deviations in the engine speed

  towards higher speeds, corresponding work points

  on the decreasing adjustment characteristic

  health, while in the case of engine rotation speeds which deviate from the set number of revolutions towards lower speeds, work points are automatically placed on the

  full load limitation feature.

  According to the invention, this problem is solved by the fact

  that the circuit intended to form the variable voltage of quan-

  injected unit comprises the following components: - a second comparator device to which are connected in

  permanently, from the input side, the instant signal of a component

  intended to form the decreasing adjustment voltage variation and the output of an input device,

  - a bistable switching device, the second of which

  trée is connected to the output of the comparator device and the first input of which is connected to the formatter, the rear flank of the injection pulse producing the trigger, - a door for the pulses coming from the generator disc

  door, which is connected directly or indirectly

  at the output of the bistable switching device and the output of which is connected to the input of the component intended to form the voltage variation of the quantity of full load, - a component for the formation of the voltage variation of the quantity of decreasing adjustment , which can be switched by the bistable switch device and to the input of which is connected the output of the component forming the voltage variation of the full load quantity, while its output

  is connected to the analog memory input.

  In order to act on the plot of the decreasing adjustment characteristics, the component forming the variation of decreasing adjustment voltage can be controlled as a function of signals from the input device or other signals depending on the state.

engine operation.

  The aforementioned component is advantageously produced under the

  form of a discharge circuit with controlled discharge constant

  goddess. According to one development, it is possible to give the decreasing adjustment characteristics of different slopes by inserting, between the output of the bistable switching device and the input of the door, a delay circuit whose delay time is adjustable by means of the signals from the input device connected to its control input or by means of other signals depending on the operating state

of the motor.

  In order to be able to carry out in a manner known per se a

  injection setting, also with this installation

  Injection with a characteristic of a regulator which is the reference voltage and applied with the value ro, in a manner known per se, to an input of the dioposi: ti :: com'i aa; eur while it is connected, to another input, the output of an adder whose first input receives the voltage which decreases over the extent of the injection range, and whose

  second input receives the displacement voltage.

  In a manner known per se, there is provided a displacement tension generator which forms the displacement tension from the speed of rotation of the crankshaft and / or other

  engine parameters or vehicle operating parameters

  cule. However, an injection setting is also possible.

  sible in another way known per se, by the fact that it is connected to the comparator device, at one of its inputs, the output of the displacement voltage generator, while it is connected, to its third input , the output of an adder whose first input receives the displacement voltage and whose second input receives the quantity injected voltage. In this embodiment also, the displacement tension is formed in a manner known per se, in the displacement tension generator, from the rotation speed of the crankshaft and / or other parameters of the engine.

  or vehicle operating parameters.

  In order to be able to further develop a corrective voltage

  tion in the injection system produced according to the invention

  tion, it is connected in a manner known per se to the comparator device, at its second input, the output of an adder and, at its third input, the output of another adder,

  the entries of the first mentioned adder received

  on the one hand the voltage which decreases in the injection range

  tion and, on the other hand, the correction voltage, while the inputs of the second adder receive on the one hand the voltage

  quantity injected and, on the other hand, the correction voltage.

  In a manner known per se, the voltage generator of cor-

  rection forms the correction voltage depending on the

  engine speed and / or other engine parameters

  tor. He can also train it according to parameters of

vehicle operation.

  Examples of embodiment of the invention will be described

  below with reference to the accompanying drawings.

  Fig. 1 illustrates the basic structure of the circuits

an injection system.

  Fig. 2 represents a circuit for the formation of the

amount injected voltage.

  Fig. 3 shows another modified circuit for the

  formation of the amount injected voltage.

  Fig. 4 is a graphic representation of voltages and pulses on different lines in the injection installation.

  Fig. 5 is a schematic representation of a character

  setting teristics which can be obtained with the circuit

  for the formation of the voltages of the quantity injected.

  Figs. 6 and 7 represent modifications to the basic structure of the injection installation circuits

  for the application of a displacement voltage.

  Fig. 8 represents another modification of the structure

  basic circuit layout for applying voltage

displacement and correction.

  In fig. 1 is shown the basic structure of the circuits of the injection installation of the type under consideration, which

  must be improved according to the invention.

  On the crankshaft of the internal combustion engine are mounted one or more discs 110, 210 bearing marks

  of pulses 11, 21. In the present case, the disc 210 pre-

  feels a succession of impulse marks 21, except in

  a range f in which the injection pulse is triggered

  its position within the limits of this range being varied

  corn. In circuit 10, the elevation 11 of the disc 110 is converted into a silk tooth tension P which decreases in

  the direction of rotation. This voltage U has a characteristic

  tick which descends continuously during the course of the injection range, i.e. it starts with the

  maximum tension - initial tension Uia - and lowers linearly-

  over the entire extent of the injection range P towards zero

  - final tension U (e. The former 12 forms, from the tension

  sion U, a rectangular pulse that spans the entire

  injection range and is called the injection range pulse

  tion Ip. The output 10A of circuit 10 is connected to the input E2 of the comparator device 40. The measurement time generator 23 can be triggered by its input 23E, the trailing edge of the injection range pulse I producing the effect triggering. The measurement time generator 23 produces

  a pulse In of duration tm which is called measurement period.

  The measurement period tm must be shorter than the time necessary for a complete rotation of the crankshaft at maximum rated speed. Preferably, the measurement period tm has a duration such that the measurement period pulse Im moles to the next injection range pulse I in the event of the nominal rotation speed being exceeded. Just now

  determined by the measurement time generator 23 and on

  requested by input 50E2, the signal present at input 50E1 is

  supported in analog memory 50 to be reactivated

  read by taking over during the next cycle. The analog memory 50 is connected by its output 50A to the input 40E3 of the comparator device 40. The circuit 300 is the circuit

  intended to form the variation of voltage of quantity injected.

  The comparator device 40 forms the injection pulse IE. The inputs 40El, 40E2, 40E3 of the comparator device 40

  receive a reference voltage Ub, the angle angle voltage of

  jection Ut and a voltage of quantity injected EMU. When the

  injection angle voltage U and the quantity voltage injected

  tee UE are equal, the IE injection pulse is triggered; 0l it is terminated when the injection angle voltage U and

  the reference voltage Ub are equal.

  The reference voltage Ub is produced in a generator

of reference voltage 60.

  In fig. 2 shows the circuit for the formation of the variation in voltage of the quantity injected 300, with the components which form part thereof. The entrances to door 324 are

  connected to the output of sensor 20 and to that of a device

  switching device 326, consisting of a bistable multivibrator.

  The output 324A of the gate 324 is connected to the input 322E of a component 322 forming the variation in voltage of the quantity of full charge, produced in the form of a circuit with charging diodes

in itself known.

  To the component 322 is added a component 327 for the formation of the voltage variation of decreasing adjustment quantity, the input of this being connected to the output 322A of the component 322. The component 327 contains a discharge path which can be connected to the output 326A by the input 327E2 and which can be controlled by the input device 325 with regard to the discharge constant, by means of the input 327E3. Component 327 is connected, from the output side, to input 50E of memory 50 and to an input 330E1 of a second comparator device 330, to the other input 330E2 from which the output signal of the input device is applied 325. The bistable switching device 326 is connected, by its first input 326E1, to the output 121A of the former 121,

  the rear edge of the injection range pulse I (e pro-

  invoking its triggering and, consequently, the appearance of a

output signal at its output 326A.

  The second input 326E2 of the switching device 326 is connected to the output 330A of the second comparator device 330. According to a variant of the circuit 300, illustrated in FIG. 3, a controlled delay circuit 323 is interposed in addition, by its input 328E1 and its output 328à, between output 326 A and input 324E, input 328E1 being connected to output 326A and output 328A being connected h input 324E2o input 328E2

and connected to output 325A.

  To come to the operating mode of. device, we will consider in particular below the mormatik of the voltage voltage of quantity injected into the circuit 500 The treatment of the voltage from j ^ ject to party

  from analog memory 50 until the pulse is triggered

  corresponding injection time of duration tE is described in

  details in German Democratic Patent No. 120,508.

  At each revolution, the circuit 300 establishes a voltage which corresponds, as a function of the comparison of the actual and set rotation speeds, to the characteristic of

  full load or with decreasing adjustment characteristics.

  From this voltage variation, by means of the analog memory 50 and of the measurement time generator 23, the voltage of quantity injected UE which is applied to

  the input 40E3 of the comparator device 40.

  When the crankshaft rotates at a speed that is

  below the set speed predetermined by the device

  positive input 325, the following signal flow occurs: the pulses I21 pass gate 324 through the input

  324E1 thereof and form, in component 322, a varia-

  tion of voltage which corresponds to the characteristic of quantity injected at full load. Without being influenced by the component 327, this voltage variation reaches the output 300A -C, from there to the input 5EO of the analog memory 50. At each revolution is carried out, by the measurement time pulse Im at

  input 50E2, the order of taking charge of the value of

  correct sion i in analog memory-50, value which is then applied, by output 50 1 of this memory, to

  the input 40E3 of the comparator device 40.

  When the engine speed exceeds the speed

  set point introduced by means of the input device 325,

  the second comparator device 330 launches, when the

  Sement, a signal which arrives, via its output 330A, at the input 326E2 of the bistable switching device 326. The output 3261 of the latter is thus switched and there is a blocking of the gate 324 at the input 324E2 of which is connected to output 326. By blocking the door 324, further formation of the voltage variation is pocketed in the component 322 which is preferably produced in the form of a charging diode circuit. The output signal modified at the output 326 activates, by its input 327E2, the component 327 for the formation of the voltage variation of decreasing adjustment quantity. Component 327 constitutes a discharge circuit which can be inserted by its input 327B2 and which can be adjusted, as far as its discharge constant is concerned,

  by its input 327E3. In cooperation with exit 322A from.

  component 322, an adjustable discharge time constant can

be obtained.

  The modification of the discharge constant by the input 327E3 is carried out by means of the input device 325, a

  corresponding discharge constant and therefore a varia-

  correspon- ding setting quantity voltage setting

  dante being associated with each preset speed setting

  (see in this regard fig. 5, zone III, decreasing adjustment characteristics a to a "'. If the discharge constant must be kept constant for all the set target speeds, which is also possible, it is necessary '' establishes, for all set speeds, similar decreasing adjustment characteristics, simply shifted parallel in

the characteristic area.

  From the voltage value applied to output 322A and, consequently, to input 327E1, component 327 forms, by reduction of this value, a voltage variation which

  determines, using analog memory 50 and the general

  measurement time sensor 23, the quantity voltage injected EMU

  which corresponds each time to a point on one of the characteristics

  decreasing adjustment ticks associated with the preselected speed of rotation, for example a, a '. This association is made by the input device 325, the output of which is connected to the input 327E3 of the component 327. The processes

  corresponding to each situation of rotation speed effected

  tive are repeated at each engine revolution. To this end, the bistable switching device 326 is influenced at its

  input 32631 through the trailing edge of the input range pulse

  jection I p -, so that the pulses I21 can

go through door 324.

  The patterns of the pulses corresponding to the processes described are shown in FIG. 4, and this in the case where the set target speed has been exceeded. The variant of the circuit 300 shown in FIG. 3 comprises the adjustable delay circuit 328, intended to influence the variation of

  decreasing setting amount voltage. In case of use

  tion of such a circuit, it is only at the expiration of a time

  delay set by means of input 328E2 under the

  dance of the input device 325, that the passage of the pulses I21 through the gate 324 is blocked, that is to say that the blocking occurs with delay. Since immediately

  after exceeding the set target speed, the com-

  posing 327 is activated by means of its input 327E2 by the device

  bistable switching positive 326, the effects of the components overlap during the delay time

  322 and 327, resulting in a smoother start of the setting

  croissant. Functionally, there occurs in component 322 a rise in voltage by pulses I21, but

  at the same time, it intervenes permanently, by means of the

  sant 327, a discharge and, consequently, a decrease in the

tension established.

  In order to be able to introduce, in addition to the duration tE of the injection pulse, a constant displacement over time, so as to shift the injection angle NEZ within the limits of the injection range (according to the requirements of the engine, a complement

  of the basic structure of the circuits of the injection system

  tion is possible according to fig. 6. the desired displacement is effected by a displacement voltage Uv, by which the due voltage is lowered by level with respect to the reference voltage Ub, that is to say throughout the injection range The displacement voltage Uv is therefore permanently subtracted

  of the voltage U (>. This is done in the adder 13.

  The displacement voltage Ut is produced in the generator

  displacement tension 14 as a function of the speed of the crankshaft

  quin nk and it is applied with the voltage U / to the addi-

holder 13.

  A displacement of the injection of a displacement time t v

  can also be obtained in another way by modification

  tion of the reference voltage Ub (see fig. 7 in this regard).

  The displacement voltage Uv coming from the displacement voltage generator 14 is additively combined, by means of an adder 15, at equal quantities with the voltage of

  Ub reference on the one hand and with the quantity tension injected

  tee U on the other hand. Thus, the level of the voltages Ub and UEM is modified in the same way with respect to the voltage U In practical operation, it also appears that it

  there is a difference in time between the course of the

  injection time and the duration of the injection pulse.

  This difference results from the conditions that exist inside

  inductivity in a DC circuit,

  as well as mechanical processes in the magnetic valve.

  The relationship between the duration tE of the injection pulse and the duration tEZ of the injection is defined by the equation tEz = tE + tke

  tk representing a correction time.

  It is desirable that the correction time tk remains small compared to the duration tE of the injection pulse. Compared to the rotation of the crankshaft, the injection time tEZ extends over the entire extent of the angle d 'injection Ez' equi is the sum of the injection implantation r r and a correction angle ok To take this into account, it is necessary to deduce the tlea sion of quantity injected UE of the voltage of correction Uk, since the injection time tEZ is made up of the duration tE of the injection pulse depending on the quantity of the quantity dez.ndan of the Cs, dquantit ijec6ée CUEm and the correctlor time; ko this subtraction operation in the adder 150 (-see fig. 8). But at the same time, in relation to the anugles, 's Ik' YEZ which are established in an interdependent manner at very high rotational speeds, the sawtooth tension U must also be corrected, in order to always obtain a

  constant end of the injection time topo Gela is-

  performed by subtracting the correction voltage Uk from the

  sawtooth tension Uo in the adder 130. At the addi-

  tensioner 150 is applied on the one hand the EMU voltage from

  analog memory 50 and, on the other hand, it receives the voltage

  correction voltage Uk from the correction voltage generator 16. At the output of the adder 150 appears the difference in voltages UEM minus Uk which must be applied to the comparator device 40. Thus, the correction voltage Uk is introduced subtractively, as well in tension

  sawtooth Up than in tension product Up.

  p The schematic diagram in fig. 8 makes possible a displacement and a correction at the same time. Indeed, in

  the adder 130, the voltage Ub can be modified additi-

  vement, both by the displacement voltage Uv and by the correction voltage Uk, before being applied to the device

comparator 40.

  A detailed description of the effect of the

  modifications shown in fig. 6 to 8 in the patent

  of Democratic Germany n2 120 508, description therein

  given using representations of pulses and voltages.

  According to a development of the invention, the formation of the displacement voltage Uv and / or of the correction voltage Uk can be influenced by operating parameters of the vehicle, for example the voltage on board the latter. It is thus possible to compensate for voltage oscillations in the vehicle network, with the influence that they exert on

  the dynamic behavior of the electromagnetic valves of

  jection. It is also possible to arrange for the pressure in the fuel tank to influence said voltage, in order to ensure an accurate metering of the quantities.

injected.

Claims (12)

  1. Electro- controlled fuel injection system   nique for internal combustion engines, with which the duration of the injection is variable in order to proportion the quantity injected and in which it is planned, to place the appropriate pulses of injection control in coincidence with the position of the crankshaft of the internal combustion engine, the following electronic components: Circuits to form respectively: - an injection range pulse, - a voltage which decreases in the injection range as a function of the angle of rotation of the crankshaft, - a voltage of quantity injected as a function of the signals of a data input device and of the speed of rotation of the crankshaft, in a constant measurement period, determined by a measurement time generator triggered by the trailing edge of the pulse injection range, a component being provided to form a voltage variation from a number of pulses detected in a time interval and coming from an imaging disc drives mounted on the crankshaft, - a reference voltage; and an analog memory which is mounted following the circuit   forming the amount injected voltage, is also controlled   given by the measurement time generator and retains the voltage of the quantity injected,   as well as a comparator device to which are directly connected   directly or indirectly, on the input side, the outputs of the circuits forming the voltage which decreases in the injection range, the quantity voltage injected and the reference voltage, and at   the output of which the injection duration pulse is available   tion, characterized in that the circuit for the formation of the variation in voltage of the quantity injected (300) comprises the following components: - a second comparator device (330) to which the instantaneous signal d is permanently connected, on the input side a component (327) intended to form the variation of decreasing adjustment voltage and the output (325A) of a data input device (325), - a bistable switching device (326), of which the second input ( 326E2) is connected to the output (330A) of the comparator device (330) and the first input (326E1) of which is connected to the pulse former (12), the rear flank of the injection range pulse causing tripping of this device, - a door (324) for the pulses (I21) coming from the disc   pulse generator (210), door which is connected directly   directly or indirectly at the output (326A) of the bistable switching device (326) and whose output (324A) is connected to the input (322E) of the component (322) forming the voltage variation of full load quantity, - a component for forming the voltage variation of decreasing control quantity (327), which can be switched   by the bistable switching device (326) and at the   inlet (327E1) from which the output (322A) of the component is connected   sant (322), while the input (50E) of the analog memory   that (50) is connected to its output (327A).   2. Electro- controlled fuel injection system   A device according to claim 1, characterized in that the component (327) for the formation of the decreasing adjustment voltage variation can be controlled depending on signals from the data input device (325) or others   signals depending on the operating state of the engine.   3. Electro- controlled fuel injection system   picnic according to claim 2, characterized in that the Com-   setting (327) for the formation of the decreasing adjustment voltage variation is a discharge circuit known per se adjustable discharge constant.   4. Electronically controlled fuel injection installation according to claim 1, characterized in that it is interposed between the output (326A) of the bistable switching device (326) and the input (324E2) of the door (324) to the delay circuit including the delay time. and adjustable using signals from the data input device (325) tuned to its control input (528E2) and / or other signals depending on   the operating condition of the engine.   5. Fuel injection system with electronic control   A connector according to claim 1, characterized in that it is applied in a manner known per se to the input (40E1) of the comparator device (40), a reference voltage of zero value while it is connected, to its input ( 40E2), the output (13A) of an adder (13) to the first input (13E]) dnuq1cl is applied the decreasing voltage (U%) and to the second input (13E2) from which a displacement voltage is applied ( W) 6. electronically controlled fuel injection installation according to claim 5, characterized in that, in a manner known per se, the displacement voltage (UV) can be formed in the displacement voltage generator (l. ) from the speed of rotation of the vi! ebreqin and / or others engine parameters.   7. Electro- controlled fuel injection system   screw according to claim 1, characterized in that, in a manner known per se, it is connected to the comparator device (40), at its input (40E1), the output (14A) of the displacement voltage generator (14), while . that it is connected, at its input (40E3), the output of an adder (15) to the first input (15El) from which the displacement voltage is applied   (Uv) and to the second input (15E2) from which the voltage is applied Injection quantity quantity (EMU). e   8. Electro- controlled fuel injection system   screw according to claim 7, characterized in that, in a manner known per se, the displacement tension (Uv) can be formed in the displacement tension generator (14) from the rotational speed of the crankshaft and / or d 'other engine parameters.   9. Electro- controlled fuel injection system   screw according to claim 1, characterized in that, in a manner known per se, it is connected to the comparator device (40), at its input (40E2), the output (130A) of an adder   (130) and, at its input (40EB3), the output (150A) of an addition-   neur (150), the decreasing voltage (U) on the one hand and a correction voltage (Uk) on the other hand being applied to the inputs (30E1, 30E2) of the adder (130), while the quantity voltage injected (UEM) on the one hand and the correction voltage (U) on the other hand are applied to the inputs (150El, E2) of the adder (150).   10. Electro-controlled fuel injection system   hique according to claim 9, characterized in that, in a manner known per se, the correction voltage (Uk) can be   formed in the correction voltage generator (16) from   shooting of the rotational speed of the crankshaft and / or others engine parameters.   11. Electro- controlled fuel injection system   picnic according to claim 5, characterized in that the tension   displacement voltage (UV) can be formed in the displacement voltage generator (14) also according to other   vehicle operating parameters, for example the voltage   on board, the pressure in the fuel system rant.   12. Electro- controlled fuel injection system   picnic according to claim 8, characterized in that the tension   displacement voltage (UV) can be formed in the displacement voltage generator (14) also according to other   vehicle operating parameters, for example the voltage   on board, the pressure in the fuel system rant.   23. Electro- controlled fuel injection system   pic according to claim 10, characterized in that the correction voltage (Xk) - can also be formed in the correction voltage generator (16) as a function of other operating parameters of the vehicle, for example the voltage   on board, the pressure in the fuel system. -