DE2008350A1 - Fuel injection system for internal combustion engines with direct or indirect injection - Google Patents

Description

Fuel injection system for internal combustion engines with direct or indirect injection

Addendum to patent ....... (patent application P 15 76 280.8-13)

In the main patent (patent application P 15 76 28O.8-I3)

an electronic injection control system has been described which comprises at least two semiconductor elements, such as transistors or bistable multivibrator having thyristors to control the beginning and the end of the injection, the Beginning is triggered by a pulse fed to the control electrode of one of the semiconductor elements, which is triggered by one of the rotation of the motor stems from the pulse generator or pick-up controlled by the motor and the end is controlled by a second pulse, the after one not immediately from the rotation of the engine

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dependent time period from a multiple independent inputs having timing element. The timer has a Double base diode, the emitter of which is connected to a resistor and a capacitor, the latter via the said resistor is charged to a certain controllable potential, while the two bases of the double base diode are connected to a different potential, so that the triggering of the second signal takes place when the both potentials are the same except for a certain factor.

In a preferred embodiment of the fuel injection system of the main patent (patent application

P 15 76 28O.8-I35) a sawtooth generator is provided which has a double base diode, a resistor and a low value adjustable capacitor and at the end of each Relaxation oscillation period gives a pulse to the base of a transistor that is part of a monostable or is a bistable multivibrator, which is intended to generate signals with a constant peak value, but with a dependent from the basic control parameters to generate variable frequency, these signals for charging the capacitor of the timer serve.

The setting of the ripple oscillation period of the sawtooth generator is done with the help of an adjustable one Capacitor of low capacitance, so that it is possible to achieve mean relaxation oscillation frequencies of ICr Hz.

The adjustable capacitor according to the main patent

(Patent application P 15 76 280.8-13) consists of two or more concentrically arranged, by insulating Intermediate layers separate axially displaceable tubes that allow a linear relationship between

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this shift and the duration of the injection.

However, it has been found that the frequency of the sawtooth generator in certain cases it is not high enough to allow sufficient fineness of the regulation of the injection duration as a function of the various parameters of the operating conditions or the operating state of the engine. In addition, there are relatively large displacements of the one in the adjustable condenser made of concentric tubes Electrode of the capacitor relative to the other necessary, which is not always easy to achieve.

The object of the present invention is to overcome these disadvantages to avoid. According to the invention, this object is based on a fuel injection system with a beginning and the end of the injection control bistable multivibrator, the start of the injection triggered by a pulse that of the bistable multivibrator of one of the Rotation of the motor controlled pulse generator is fed and the end of the injection is controlled by a second pulse which comes from a timing element that has several independent inputs that adjust the injection duration depending on the basic control parameter and on

Allow correction parameters, according to the main patent

(Patent application P 15 76 280.8-I3) achieved in that the Timing element has a high-frequency sawtooth generator, the output pulses of which are fed to a pulse shaping device are generated, the square-wave signals, the frequency of which is the same as that of the sawtooth generator, but their duration as a function can be varied by parameters of the operating conditions or the operating state of the engine and that in an integration device be integrated, the one the end, the

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Injection effecting pulse emits when the integration gives a predetermined value.

There is preferably a connection between the sawtooth generator and the bistable flip-flop which controls the injection provided so that the sawtooth generator can be triggered with the pulse causing the start of the injection and with the impulse causing the end of the injection can be blocked.

Alternatively, between the Impulsformervorrichtung for the high frequency pulses and the integration means for integrating the square wave signals an electronic gate of the type "üT be provided, which is opened by the injection K- controlling, flip-flop with the start of injection causing pulse and with which the End of the injection effecting pulse is closed, the sawtooth generator and the pulse shaper device are continuously switched on and the permanently generated square-wave signals of the integration device are only fed when the electronic gate is open.

Other developments of the invention are set out in the subclaims 4 to 7 included.

In the following the invention is explained in more detail with reference to schematic drawings of exemplary embodiments.

It shows

Fig. 1 is a simplified block diagram of the invention Contraption;

Figure 2 is a simplified block diagram of another

Embodiment of the device according to the invention;

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Pig. j5 shows a circuit diagram according to the embodiment according to Pig. 1, in which the circuit of the timing element is shown in detail;

4 shows a modified embodiment of one of the Elements of the timer;

5 shows a schematic representation partly in section, an adjustable capacitor used in the timer.

From these figures it can be seen that the opening of the electromagnetic injection nozzles 7 * 8, 9 * 10 is controlled by an electrical square-wave signal, the duration of which determines the amount injected and that of a bistable flip-flop 12 via a distributor 18, which is necessary because the bistable flip-flop 12 is intended to control more than one injection nozzle, is supplied. The bistable flip-flop 12 is triggered by pulses that are supplied by a pickup or pulse generator 17 controlled by the rotation of the motor, not shown, and in the embodiment according to FIG The pulses supplied to the sawtooth generator 29 are fed to a pulse shaping device J> 0 , which converts them into square-wave pulses with the same frequency but adjustable duration, the adjustable duration depending on the basic control parameters of the control system supplied by a consumer or a measuring device 20. These square-wave signals are fed to an integration device 31, which emits a signal which causes the end of the injection and blocks the bistable multivibrator 12. This signal causing the end of the injection is generated when the integration of the square-wave signals emitted by the pulse shaping device 30 reaches a predetermined variable value which is determined by the

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auxiliary or correction parameters supplied by the consumers or measuring devices 21 to 25 depends. In the case of an in A motor vehicle used with a controlled ignition engine can be the basic control parameter of the regulation of the negative pressure be in the suction line or in the suction lines from a consumer or a measuring device 20, preferably a pressure sensor. The correction according to the ambient atmospheric pressure is made by a consumer or a measuring device 21, preferably a pressure sensor, determined and the engine temperature is determined by the measuring device 22, preferably a temperature sensor, the temperature of the intake air through the measuring device 2j5 * preferably a temperature sensor, the speed of actuation of the opening of the throttle valve in the intake line controlling accelerator pedal by the measuring device 24 and the speed of the engine by the speed measuring device 2i> established. This results in a duration of the injection output by the bistable flip-flop 12 controlling square-wave signal, which corresponds exactly to the current requirements of the motor.

In the exemplary embodiment according to FIG. 2, the sawtooth generator 29 and the pulse shaper device 30 continuously fed by the voltage source as soon as the contact or ignition key is operated, for example, and the square-wave signals constant frequency, but adjustable duration, the integration device 31 via an electronic

i'l /)

Gate circuit 'or an electronic gate of the "· Β ¥" type 32 'supplied, which is operated synchronously with the rotation of the motor by the bistable flip-flop 12 every time the latter receives a signal causing the start of an injection. With this embodiment one can avoid the random deviations or avoid irregularities that can occur,

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every time the sawtooth generator 29 is triggered. With In addition, this system allows only one Sawtooth generator 29 and a single, controlled by a single measuring device 20 pulse shaper device ^ O zu use to any number of bistable flip-flops 12 a signal causing the end of the injection to deliver. This benefit is especially valuable when the Speed of a multi-cylinder engine is so high that the injections the duration of the various cylinders of the engine overlap. In this case you can have several Provide bistable flip-flops 12 with their integration devices 51 which work together with certain groups of cylinders, wherein the injection duration by a single one of a sawtooth generator 29 and a pulse shaper device 30 existing assembly is determined.

In Fig. 5 is an electronic circuit diagram of the entire Control device according to FIG. 1 shown. The sawtooth generator 29, the pulse shaper device 30 and the integration device 31 is shown in detail. The pulse generator 17, not shown in Fig. 3, transmits its positive Signal for triggering the injection via the capacitor 700 and the diode 702 to the known bistable multivibrator 12, with a diode 701 for discharging the Capacitor 700 and a resistor 703 for deriving the Trip signal to ground are provided. The sawtooth generator 29 is via a resistor 141, which has resistors and 144 forms a voltage divider from the flip-flop 12 fed from. From the connection point between the resistors 141 and 143 there is a connection via a Resistor 142 to one terminal of a capacitor 145, whose other terminal is connected to ground, this connection point between the resistors 14l and 143 at the same time the output S of the pulses from the sawtooth generator 29

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represents. Form three transistors T 146, T 147 and T 148 a cascade circuit, wherein the emitter of the transistor T 146 with the connection point between the resistor 142 and the capacitor 3.45 is connected, while its base is connected to the connection point between the resistors 143 and 144 and is connected to the collector of transistor T 147 and its collector to the base of transistor T 147 connected is. The transistor T 148 is with its base with the emitter of the transistor T 147, with its collector with the connection point S between the resistors l4l and l43 and connected to its emitter to ground. The exit S of the sawtooth generator 29 is via a diode 149 and a capacitor 151 to the input E in the present case a monostable multivibrator of a special type having pulse shaping device 30 connected, wherein a resistor 150 between ground and the connection point between the Diode 149 and capacitor 15I is provided to the Discharge capacitor 151 after the passage of the signal '.

The pulse shaping device 30 comprises essentially Transistors T I58, T 159 and T I60 that are cascaded form, the base of the transistor T 158 by means of one consisting of resistors I62 and I6j5, on the one hand with the voltage source supplying the supply voltage Va and on the other hand connected to ground voltage divider is held at a certain potential while the emitter this transistor T 158 is connected to the voltage source via a resistor I56. In addition, there is a connection between the base of transistor T 158 and the Collector of transistor T 159 and between the collector of transistor T 158 and the base of transistor T 159 provided, the emitter of the latter to the base of transistor T 160 and through a resistor 16I to ground

0 0 98 Ul / 10 95

is connected and the emitter of the transistor T l60 is connected to ground, while its collector is connected via a resistor • l64 to the voltage source and at the same time represents the output S of the pulse shaping device JQ .

The duration of the square-wave signal obtained at the output S of the pulse shaping device 30 is determined by the value of the resistor 156 and the capacitance of an adjustable capacitor 157, the latter being connected on the one hand to ground and on the other hand to the connection point between the resistor 156 and the emitter of the transistor T I58. It is triggered by a transistor T 153 * whose base is connected to the input E of the pulse shaping device J> 0, which is connected to ground via a resistor 152, and whose emitter is connected to ground and. the collector of which is connected on the one hand to the voltage source via a resistor 154 and on the other hand to the emitter of the transistor T 158 via a diode 155.

The integration device 3I comprises a double base diode T 805, the second base of which is connected via a resistor 804 to a point 80I, to which a voltage is applied which is determined as a function of the auxiliary values determined by means of the measuring devices 21, 22, 27), 24 and 25. or correction parameters can be changed, the emitter of this double base diode T being connected to ground via a resistor 802, a capacitor 806 and a diode 807 and to the output S of the pulse shaping device j50 via a diode II7. The signal causing the end of the injection is fed to the bistable multivibrator 12 via a connection branching off from the connection point between the diode 807 and the capacitor 806 via a resistor 854. .

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The puncture of the device is described below. When the bistable multivibrator 12 is triggered, the capacitor 145 charges through the resistors l4l and i42 on. During this time, the transistors T 146, T 147 and T 148 not conductive, since the potential at the emitter of transistor T 146 is even lower than the potential, that of the one consisting of the resistors 14l, 143 and 144 Voltage divider is placed at its base. At the moment when the voltage of the capacitor 145 becomes a little higher than that applied to the base of transistor T 146, this becomes conductive, causing transistors T 147 and T 148 also become conductive. This has the effect that the voltage at the base of the transistor T 146 is practically zero is achieved, whereby a rapid discharge of the capacitor 145 is achieved. In addition, the transistor T 148 the voltage of the point S is reduced to zero, which allows very high oscillation frequencies even with relatively high frequencies to achieve high values of the capacitor l45. As soon the capacitor 145 is completely discharged, the transistors T 146, T 147 and T 148 are again non-conductive, and the cycle begins again. You therefore have a positive voltage at the output S of the sawtooth generator 29, each time is briefly returned to zero when the transistors T 146, T 147 and T 148 are conductive. So it will be every time this Voltage rises again to the value Va of the supply voltage, a positive pulse via the diode 149 and the capacitor 151 the base of the transistor T 153 of the pulse shaping device 30 supplied, whereby this transistor T 153 becomes conductive. Now, however, the transistors T I58, T 159 and T 160 are normally conductive as long as the transistor T 153 is not conductive, since the current through the resistor 156 is sufficient to make them to keep in this state. When the transistor T 153 becomes conductive, the applied to the emitter of the transistor T 158 falls

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Potential to a value which is approximately equal to zero and the holding current is thus suppressed. Hence the Transistors T I58, T I59 and T 160 not conductive, so that the adjustable capacitor 157 is on the. resistance 156 begins to charge as soon as transistor T 153 stops being conductive. Because of this, the rate at the emitter increases of the transistor T 158 applied voltage again and the latter is determined by the values of the resistor I56 and the adjustable capacitor 157 dependent tent again. While the A positive square wave signal appears on capacitor 157 Output S of the pulse former device 30, the same Frequency as the sawtooth generator 29 has its duration However, due to the adjustability of the capacitance of the capacitor 157 is adjustable.

These square-wave signals are then fed to the integration device: 31 and charge the capacitor 806. When this capacitor 806 reaches a voltage which, apart from a certain factor / I inherent to the circuit, is equal to the voltage applied to the double base diode T 805 via the point 8:01: 1st, the latter suddenly becomes conductive due to an avalanche discharge, and the capacitor 806 is discharged. This has the effect that a negative pulse is applied to the bistable multivibrator 12, which blocks it and thus controls the end of the injection.

It can be shown that with the circuit described the square-wave signal emitted by the bistable multivibrator 12 it has the following duration

• ^R 802 · ^C 806

If one now uses an adjustable capacitor 157 of the type shown in Fig. provides the type shown, which a fixed part 157a and a guided in a support 157c movable part 157b, the duration of the square-wave signal is a linear puncture of the distance £ between the two parts 157a and 157b of the adjustable capacitor 157:

T = ^(R 14l + ^R 142) ^C 1445 * ^R 802 ' ^C 8O6

^R I56 * ^A * e

802 · ^c 806

^R I56 · ^A · ^s
considering that

c- - A ä

^C I57 "'e

is. It is

A is a proportionality factor

S is the size of the surfaces of the parts

157a and 157b and
£ the distance between the two parts.

The movable part 157b can be connected to a vacuum unit which communicates with the intake pipe of the engine stands and the displacements of the membrane of the vacuum unit can be extremely small, whereby the construction the vacuum unit is simplified.

In Fig. 4 is a modification of the pulse shaping device 30 shown. If one wishes, square-wave pulses of a relatively long duration using small capacitances it is necessary to adjust the value of resistor I56 raise. In this case, unloading or tilting of the

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Device appear at the wrong time. To avoid this, one sees an additional transistor T I65, its base with the output S and its emitter with ground and its collector via a resistor 166 with the voltage source and via a diode I67 to the emitter of the transistor T 158 is connected. This transistor T I65 is conductive for the entire duration of the square wave signal, so that its collector. tor is practically at zero potential and therefore the transistor T 158 cannot feed via the diode 167. The transistor T I65, on the other hand, is non-conductive during the time while the transistor T 158 is in the conductive state and holds the latter above resistance 166, which can be very weak can, in this state.

All information and characteristics disclosed in the documents are claimed as essential to the invention, insofar as they are individually or in combination new compared to the state of the art,

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Claims (7)

Claims Fuel injection system for internal combustion engines with airekter or indirect injection, which has a beginning and Has the end of the injection controlling bistable multivibrator, the start of the injection triggered by a pulse which is fed to the bistable multivibrator from a pulse generator controlled by the rotation of the motor "and the end of the injection by a second pulse is controlled, which comes from a timer that has several independent inputs that have a setting allow the injection duration depending on the basic control parameters and correction parameters, according to the main patent (Patent application P 15 76 200.8-13), thereby characterized in that the timing element has a high-frequency sawtooth generator (29) whose output pulses fed to a pulse shaping device (j50), generates the square-wave signals, the frequency of which is the same as that of the sawtooth generator (29), but their duration is dependent of parameters of the operating conditions or the loading ) The operating state of the engine can be varied and which are integrated in an integration device (J> \) which emits a pulse that causes the end of the injection when the integration results in a predetermined value. 2. Fuel injection system according to claim 1, characterized characterized in that between the sawtooth generator (29) and the bistable flip-flop which controls the injection (12) a connection is provided so that this sawtooth generator (29) with the start of the injection causing pulse can be triggered and with the pulse causing the end of the injection can be blocked. 009842/1095 ^{3 · Fuel injection system according to claim 1, characterized in that an electronic gate (32) of type 11} JST is provided between the pulse shaping device (30) for the high-frequency pulses and the integration device (31) for integrating the square-wave signals, which gate controls the injection , bistable flip-flop (12) is opened with the pulse causing the start of the injection and closed with the pulse causing the end of the injection, the sawtooth generator (29) and the pulse shaper device (30) are continuously switched on and the square-wave signals permanently generated by the latter Integration device (3I) can only be supplied when the electronic gate (32) is open. 4. Fuel injection system according to one of the preceding Claims, characterized in that the Sawtooth generator (29) one with its one connection to ground and one with its other connection to the emitter first transistor (T 146) and two resistors (14l, 142) connected to the input of the sawtooth generator (29) Has capacitor (145), the base of the first transistor (T 146) via a resistor (143) to the connection point between the resistors (141, 142) and via a further resistor (144) is connected to ground, and wherein a second transistor (T 147) is provided, the collector of which to the base of the first transistor (T 146) and its base to the collector of the first. Transistor (T 146) connected while the emitter of the second transistor (T 147) is connected to the base of a third transistor (T 148), the collector of which is connected to the connection point of the resistors (l4l, l42 and 143) and its emitter is connected to ground. 5 · fuel injection systems according to one of claims 1 to 3, by g «" indicates that the pulse shaper 42/1095 device (30) a monostable multivibrator with three one Cascade circuit forming transistors (T I58, T 159 and T. 160), the first transistor (T I58) with its base with the center tap of a voltage divider (162, 163), with its emitter via a resistor (156) with the voltage source and with its collector with the base of the second transistor (T 159) is connected, the collector of which is connected to the base of the first transistor (T 158) and the emitter of which is connected to the base of the third transistor (T I60) and to ground via a resistor (I6I), and the third transistor (T I60) further with its collector via a resistor (164) with the voltage source and with its emitter is connected to ground, and that the pulse shaping device (j5O) has a fourth transistor (T 153), its base via a resistor (lt> 2) with ground, its emitter is connected directly to ground and its collector is connected directly to the voltage source via a resistor (154) is, the collector also with the connection point between a resistor (I56), the emitter of the transistor (T I58) and an adjustable capacitor (157) connected to its other connection to ground connected is. 6. fuel injection system according to claim 5, characterized characterized in that the adjustable capacitor (157) has two parallel metallic plates (157a, 157b) one of which (157a) is fixed and the other (157b) is axially displaceable to approach or move away from the first to remove this, the displacement of the displaceable plate (157b) by means of a pick-up or measuring device in Depending on the basic control parameters of the motor is controlled. 0098A2 / 1095 7. Fuel injection system according to claim 5 »thereby characterized in that the pulse shaping device has an additional transistor (T I65) which intended .ist, discharges or tilting of the pulse shaping device (30) at the wrong time and the one with its emitter with ground, with its base with the collector of the third transistor (T I60) and with its collector on the one hand via a resistor (I6.6) to the voltage source and on the other hand is connected to the emitter of the first transistor (T I68) via a diode (I07). 00 98 427 10.95