DE2014633A1 - Electronic mixture dosing system - Google Patents

Description

E. 9826
23.3.1970 Sk / Sz

Attachment to
Patent application

ROBERT? BOSCH GMBH, 7 Stuttgart 1, Breitscheidstrasse -4-

Electronic mixture dosing system

The invention relates to an electronically controlled or a regulated system for metering the mixture in gasoline engines.

Such mixture metering systems have the main task of the concentration of unburned or incompletely burned Components in the exhaust gases from internal combustion engines j to belittle. Systems are known which completely supply fuel in coasting mode above idle speed prevent, but there are other operating states of the Internal combustion engines that require exhaust gas decontamination and is also possible. ■ ■

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109842/0819

Z0U633

Robert Bosch. GmbH · R. 9826 Sk / Sz

Stuttgart

A well-known process for exhaust gas detoxification is post-combustion the exhaust gases in a special reactor. However, this method increases gasoline consumption, and also the reactor is expensive. The invention is therefore based on the object by means of electronic control or regulation the excess air ratio λ in as many operating states as possible adjust the internal combustion engine so that optimally detoxified exhaust gases result.

The excess air ratio λ is a measure of the composition of the fuel-air mixture. It is defined in such a way that \ = 1 for a stoichiometric mixture.

The toxic components of the exhaust gases are particularly unburned Hydrocarbons, carbon monoxide and nitrogen oxides are removed.

A particularly effective solution is obtained if, according to the invention, an electronic function generator is present, depending on the operating parameters of the engine, the fuel metering controls or regulates that in each Operating condition of the engine certain, predetermined values of the Excess air ratio λ can be achieved.

Further details and useful developments are shown below with reference to in the drawing and Described and explained embodiments explained with diagrams.

Show it:

1 shows in a diagram the dependence of the CH and NO concentration on X and on the ignition time,

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Fig. 2 in a diagram the dependence of the CH and CO concentration from the spark duration,

Fig. 3, Λ, -5 and 10 block diagrams of four exemplary embodiments,

6 shows the circuit diagram of the electronic function generator for the third embodiment,

7, 8, 9 are diagrams to explain the mode of operation of the electronic function generator shown in FIG. 6, jjl

In Fig. 1, the emission of toxic exhaust gases is a function of the excess air figure λ is shown. The curves 40, 41 and apply to nitrogen oxides with ignition at 25 °, 35 and 50 before top dead center. Curves 43, 44 and 45 apply to unburned hydrocarbons at. Ignition 25 °, 35 ° and before top dead center. The concentration of CO is not recorded. Like that of hydrocarbons, it also sinks increasing excess air number, but does not increase again ^ when λ> 1.2.

Accordingly, it is most convenient to operate the internal combustion engine, having ■ Λ a Luf tüberschußzahl of about 1.2. For larger Itu £ tüberschuß misfire may occur so that the concentration of hydrocarbons unverbraimter again increases sharply, as shown in FIG. 1. In addition, it must be taken into account that the maximum output of the motor is achieved at X = 0.9.

A sensible compromise between the requirements on the one hand high engine performance and, on the other hand, favorable exhaust gas composition is possible according to the invention in the following way: A fuel-poor mixture is set in the range those driving conditions that are preferred in city traffic

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Robert Bosch GmbH ■ R. 9826 Sk / Sz

Stuttgart

come where exhaust gas is detoxified as well as possible, but not the maximum power of the engine is required; a fuel-rich mixture becomes in those operating conditions which require high engine power, but do not place particular emphasis on the purity of the exhaust gases must be, so especially in overland traffic.

As a criterion to distinguish between the two groups of operating states is the Fahrge- ™ according to the invention speed used.

The first embodiment shown in Fig. 5 is for an internal combustion engine operating with gasoline injection is provided. However, it can also be used for carburetor engines without significant changes.

An accelerator pedal 15 actuates a throttle valve 12 of the internal combustion engine, which is otherwise not shown, which is mounted in the intake pipe 11 and thus controls the air flow to the cylinders. This air supply is either with a heated temperature sensor 15, which is cooled by the air flow, or measured with a baffle plate 15a. To convert this Measured values in electrical signals of suitable amplitude, an air flow actual value transmitter 16 or 16a is provided, the output of which is connected to a first input of an electronic function generator. The opening angle of the throttle valve 12 becomes measured with a throttle valve angle transmitter 14, the output of which is at a second input of the electronic function transmitter 19 is connected. At a third input of the function generator 19, a multivibrator 18 is connected, the pulses at a frequency proportional to the engine speed. The input of the multivibrator 18 is to the primary winding 17 connected to an ignition coil, not shown.

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The only output of the function generator 19 is at a first Input of a differential amplifier 20 connected. This Differential amplifier belongs to a servo adjustment device, which also contains an electromagnetic actuator 21 and a metering throttle actual value transmitter 23 and for Setting the metering throttle 22 is used.

The function generator 19 gives a setpoint value for the fuel inflow to the injectors. This setpoint value is transferred from the differential amplifier 20 to that coming from the actual value transmitter 23 Actual value compared. If the target value is greater than the actual value, the metering throttle 22 is of the electromagnetic Actuator further open.

The function generator 19 is designed so that it emits an output signal that depends on the air flow through the intake manifold. The speed and the throttle position are controlled by the Multivibrator 18 and the actual value transmitter .16 given as correction signals to two further inputs of the function transmitter 19.

The fuel is metered in such a way that there is a suitable excess air ratio in all operating states of the engine λ is reached.

In the z _f wide embodiment, which is shown in Fig. 4, the function generator for both the metering of the fuel as well as the combustion air ensures.

It is an electronic function generator 25 with two outputs intended. The first output is connected to the input of the first differential amplifier 20 which, as in the exemplary embodiment according to FIG. 3, serves to control the metering throttle 22.

109842/0819

Robert Bosch GmbH R.- 9826 Sk / Sz

Stuttgart

The second output of the function generator is connected to the input of a second differential amplifier 26 connected, which has a second electromagnetic actuator 27 controls the throttle valve 12. To one of the three entrances of the Function sensor 25 are the throttle valve angle sensor 14, an accelerator pedal sensor 24 and the multivibrator 18 are connected.

If necessary, at two further inputs of the function generator 25 an actual value transmitter 28 for the air temperature and / or an actual value transmitter 29 for the air pressure is connected will.

In this second exemplary embodiment Both the metering throttle 22 and the throttle valve 12 are controlled via setpoint / actual value comparison circuits.

The function generator 25 receives its input size from the Accelerator pedal angle transmitter 24, 'the multivibrator 18 and the throttle valve angle transmitter 14. In a further development of the invention, the above-mentioned can be connected to further inputs of the function generator 25 further actual value transducers 28 and 29 are connected, the correction signals depending on the air temperature and release from the air pressure.

From Fig. 1 it can be seen that the nitrogen oxide concentration at \ = 1.2 is still quite high and could be reduced both by increasing the excess air ratio λ and by a later ignition point. The misfiring, which cause the strong increase in the hydrocarbon concentration in the case of larger excess air numbers, can be combated according to FIG. 2 by increasing the spark duration. In Fig. 2 is the dependence of the hydrocarbon. Substance concentration represented by the spark duration. Turn 46

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Robert Bosch GMBH . -E. 9326 Sk / Sz

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applies to λ = 0.8; 4? for λ = 0.9; 48 for λ = 1.0; 4-9 for λ = 1.1 And 50 for λ = 1.2.

The third embodiment shown in Fig. 5 has the properties of the first two exemplary embodiments and also has means to increase the spark duration to * at least 2 milliseconds or more and devices for adjusting the ignition timing. The devices for air and fuel metering are designed so that the internal combustion engine very low fuel mixtures with partial load operation Air excess numbers up to λ = 1.4- are maintained. Extending the spark duration to over 2 milliseconds results in Fig. 1 for the hydrocarbon concentrate! on the course according to curve 43a or 44a or 4-5a, so that an optimal exhaust gas detoxification is achieved.

The third embodiment according to FIG. 5 contains a function generator 32 with four inputs and three outputs. The accelerator pedal angle sensor 24, the multivibrator 18, a cooling water temperature sensor 33 and an air pressure actual value sensor 34 are connected to the four inputs. At a first exit the radio transmitter 32 is connected to a fuel control system 35, that to regulate the fuel flow to the Injection nozzles 30 is used. At a second output of the function generator 32, a throttle valve control amplifier 36 is connected, which controls the throttle valve 12 via an actuator 37 can adjust. At a third output of the function generator 32, an ignition timing adjuster 38 is connected. Whose The output is connected to the ignition system 39.

To keep the drawing as clear as possible, is only in the control device for the throttle valve, a return line 37a is shown, which enables a comparison between

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Setpoint and actual value enabled. Such return lines for the setpoint / actual value comparison can also be made with the fuel ■ Control system 35 and. provided in the ignition timing adjuster 38 be.

Fig. 6 shows the circuit diagram of the Fuhktionsgebers 32, which is provided for the third embodiment, in a bit simplified form without the cooling water temperature transmitter 33 and without the air pressure actual value transmitter 34

The output signals of the function generator 32 are shown in FIGS. 7, 8 and 9. Fig. 7 shows the dependency of the throttle valve position ar »on the accelerator pedal position <χρ · Fig. 8 shows the dependence of the fuel quantity q required for each piston stroke of the internal combustion engine on the speed η and on the accelerator pedal position αρ · In the individual curves, the accelerator pedal position ap and the associated desired air tube number λ is written. 9 shows the dependence of the pre-ignition a _z on the speed η and the accelerator pedal position ctp

The one in Fig. ' 6 contains the function generator shown as the most important Components a multiplier stage 48, a first Regelver- ™ stronger 55> a second control amplifier 61 and three Zener diodes 45, 47 and 57.

The accelerator pedal angle sensor 24 is a potentiometer or inductive Voltage divider formed, at the upper terminal 40 of which a positive DC voltage ILq is applied. From the center tap of the potentiometer 24 passes the positive DC voltage signal firstly via a resistor 43 and a second output terminal 44 to throttle valve control amplifier 36, secondly via a resistor 46 to a first input of the multiplier stage 48, thirdly via a resistor 53 to the

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Robert Bosch GMBH . . -. . ■, R. 9826 Sk / Sz _y Stuttgart; '

Input of the first control amplifier 55 and fourth via one Resistor 59 to the input of the second control amplifier 61.

The first Zener diode 45 limits the output signal of the potentiometer 24 and thus generates the kink in the curve nacii 7.

The multiplier 48 supplies through a resistor 50 and the first output terminal 51 the control signal for the fuel Control system 35 · This control signal is given by the family of curves in FIG. So that the curves for η-? Ό are not to the coordinate origin, but converge towards point A, the first input of the multiplier 48 is via a resistor 49 is supplied with a negative DC voltage IL-. A second input of the multiplier 48, the output signal of the multivibrator 18 is fed, which the Speed actual value.

For large accelerator pedal angles, the curves in the fuel map should bend, as shown in FIG. 8. The second Zener diode 4 ¹ ^ is provided for this.

While for setting the provided per piston stroke Fuel quantity the signals for actual speed value and accelerator pedal angle are multiplied with each other, these two signals are used to adjust the ignition timing at the input of the first control amplifier 55 is added so that the in Fig. 9 show parallel straight lines. The actual speed value is supplied via a resistor 52 and the accelerator pedal angle via a resistor 53.

The via a resistor 56 and a third Zener diode 57 counter-coupled first control amplifier 55 shifts the ignition

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Point in time towards ever earlier values, the higher the speed n. And the harder the accelerator pedal is depressed, but only until the accelerator pedal has reached half of its full deflection. The kinking of the straight line in FIG. 9 for high speeds is caused by the third Zener diode 57. If the accelerator pedal is depressed further than half of its full deflection, according to FIG. 9 the ignition point must be shifted back to later values. The second control amplifier 61 is provided for this. The accelerator pedal angle is fed to its input via a resistor 59 and a negative DC voltage U ^ _{2 via a resistor 60.} Because of the negative feedback via the resistor 62 and the diode 6j5, no signal appears at its output as long as the sum signal at its input has a negative value when the accelerator pedal angle is small. As soon as the input signal of the amplifier 61 becomes positive, it emits a negative output signal which is proportional to the position of the accelerator pedal. By a suitable choice of the resistor 54 · the same with z. B. double size but negative at the input of the amplifier 55 effective. The ignition point is thus shifted to later values as the accelerator pedal angle increases.

The following are the characteristics of the third embodiment again briefly summarized. The concentration of harmful constituents in the exhaust gases is determined by two basic ones Measures reduced. First, the internal combustion engine is operated with excess air to remove the hydrocarbon and to reduce carbon monoxide concentration. Second, the nitrogen oxide concentration is increased by lowering the maximum combustion temperature reduced. This is achieved by making the excess air very large (λ = 1 »4 ·). The one with it Possible combustion misfires are avoided in that, on the one hand, the spark duration is extended to a few milliseconds

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Robert Bosch GmbH ■ Rv 9826 Sk / Sz

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and on the other hand the ignition point in the direction of advance ignition is moved. Means are provided to reverse these emission control measures if by the Internal combustion engine a high performance is required * In the third The driving speed is provided as a criterion for this embodiment. Another criterion could be also has a kick-down contact as with automatic transmissions provide: The measures for exhaust gas decontamination are reversed made when the accelerator pedal is fully depressed to the stop.

The third embodiment described is a good one Compromise solution. It enables a good exhaust gas detoxification and can still be produced at a price that is significantly below, the price of exhaust gas decontamination systems with post-combustion reactors lies. ,

The exhaust gas decontamination can be done with the help of electronic mixture dosing systems to be pushed even further. Appropriate measures, however, an increase in the electronic Costs with them, are explained in more detail below with reference to a fourth exemplary embodiment.

For the incomplete combustion of the fuel in the Internal combustion engine is there except for too small an excess of air and misfires, especially in injection engines, there is a third reason: some of the fuel is still in the liquid Physical state in the form of small droplets in the cylinder .

In the case of manifold injection systems, you can determine the proportion of fuel which enters the cylinder in the liquid state; by reducing the pre-storage time

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Stuttgart

heightened, d. H. the time between injection into the intake manifold and opening of the intake valve. In the fourth embodiment means for changing the injection time are therefore provided.

Furthermore, means for exhaust gas recirculation are in the fourth exemplary embodiment into the intake pipe and to control this exhaust gas recirculation. The exhaust gas recirculation is the The concentration of nitrogen oxides in the exhaust gases is reduced as the mixture calorific value and thus the maximum combustion temperature is decreased. The same effect is achieved by increasing the excess air ratio to λ «1.4, But exhaust gas recirculation offers another advantage: The hot exhaust gases preheat the mixture in the intake pipe, thereby also the droplet-shaped portion of the fuel and thus the hydrocarbon content in the exhaust gases is reduced.

However, it is necessary to pre-cool the recirculated exhaust gases, otherwise the mixture in the intake pipe will be heated up too much and may already be ignited there.

In contrast to the first three exemplary embodiments, it is indicated in the fourth exemplary embodiment that, in addition, nor means for measuring the nitrogen oxide and hydrocarbon concentration can be provided in the exhaust pipe.

This fourth embodiment is shown schematically in FIG. An air temperature sensor 77 , the accelerator pedal angle sensor 24, the multivibrator 18, the cooling water temperature sensor 33, the air pressure actual value sensor 34 and an exhaust gas actual value sensor 75 are connected to six inputs of an electronic function generator 70. The fuel control system 35, a are connected to five outputs of the electronic function generator 70

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Einspritzzeitpunktvers plate 76, the throttle valve control amplifier 36, an exhaust gas recirculation controller 75 and the ignition point vers part he 39 connected.

The input of the exhaust gas actual value transmitter 75 is with a measuring device 74 connected to the measurement of nitric oxide and Hydrocarbon concentration is used. In an exhaust gas recirculation line 71 from the exhaust pipe, not shown leading to the intake pipe 11 is an exhaust gas recirculation throttle valve 72 attached, which is actuated by the exhaust gas recirculation controller 73 will. At the injection timing adjuster 76 are .die Injectors 30 connected. The other components are same as in the third embodiment j they are there already described.

In the fourth embodiment shown in FIG the injection valves 30 are actuated electromagnetically, namely by the injection timing adjuster 76 by electrical pulses which have a constant length and whose Deployment time is adjusted. The amount of fuel per stroke is regulated in the fuel control system 35 by a throttle.

In a variant of the fourth exemplary embodiment, not shown, the fuel control system 35 can together with the Injection timing adjuster 76 to an electronic assembly be summarized. The injection valves 30 are actuated electromagnetically by pulses, their length and the timing of which can be varied. The amount of fuel per stroke is in this case by varying the injection duration set.

Only the volume of the sucked in air can be determined from the speed and throttle valve position. For the exact setting of the

1098U / 0819

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Robert Bosch GmbH 'R. 9826 Sk / Sz

Stuttgart

Excess air ratio λ must be the mass of the sucked in Air know. Pur the electronic determination of the mass the air pressure actual value transmitter 34 and the air temperature transmitter 77 intended.

Instead of throttle position, air pressure and air temperature the air mass per stroke can also be obtained from the pressure in the intake manifold and the temperature can be determined.

In the fourth exemplary embodiment, the excess air ratio is only increased to about 1.1 to 1.2. The mixture calorific value is then further reduced by exhaust gas recirculation.

The measuring device 74 is either in the exhaust line or as shown in Fig. 10 in the exhaust gas recirculation line appropriate. It is used to measure the nitrogen oxide and hydrocarbon concentration. In the function generator 70 is a control device built in, which when passing through one or more specific points of the 'map of FIG. 1 a "comparison between the nominal value to be expected according to FIG. 1 and the actual value reported by the actual exhaust gas value transmitter 75 and if the actual value deviates from the setpoint, the setting of the function generator is corrected. This can in particular the influence of long-term drifts in the system can be eliminated.

The cooling water temperature sensor 33 is provided so that the function generator 70 is fuel-rich when the engine is cold Mixture, so a small excess air number λ can set.

The characteristic properties of the invention, namely fuel metering, air metering, ignition timing adjustment, Injection timing adjustment, extension of spark duration,

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Exhaust gas recirculation and measurement of nitrogen oxide and hydrocarbons of fkonz en tr a ti on can be incorporated in any combination in the examples. In particular, show the first three described embodiments that one is too special economical solutions with already good detoxification properties comes when only part of the proposed measures are implemented. The proposed solutions allow a detoxification of the exhaust gases without the maximum The engine power must be reduced. -

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Claims (18)

20U633 - 16 - Robert Bosch GmbH 'R. 9826 Sk / Sz Stuttgart Expectations Electronically controlled or regulated system for mixture metering in gasoline engines, characterized in that that an electronic puncture transmitter is available, the depending on the operating parameters of the engine, the fuel metering controls or regulates that in • In each operating state of the engine, certain, predetermined values of the excess air ratio λ can be achieved. 2. System for mixture dosing according to claim 1, characterized in that that the excess air number is chosen so that only when operating at full load and when operating with Mixtures that are reasonably rich in fuel at low speed and low load, but low in fuel in the rest of the range Mixtures can be adjusted. 3. System for mixture metering according to claim 1 or 2, characterized in that the electronic function generator, the fuel metering depending on the Controls or regulates the accelerator pedal position, the engine speed and the air flow in the intake system. 4. System for mixture dosing according to claim 5, characterized in that that in order to measure the air throughput - 17 109842/0819 20U633 Robert Bosch GmbH ■ · ■ - · E. 9826 Sk / Sz Stuttgart Suction system a. Orifice plate 'is used and that the The deflection values of this baffle plate are determined electronically and the electronic function transmitter are fed. - 5. System for mixture dosing according to claim 3 »characterized in that that for measuring the air flow in the intake system a heated, temperature-dependent resistor is attached in the intake air flow, its resistance value is a measure of the air throughput, and that this resistance value is used as an input variable in the electronic Function generator is introduced. . 6. System for mixture dosing according to claim 1 or 2, characterized characterized in that the electronic function generator the setting of the throttle valve and thus the air flow controls or regulates depending on the accelerator pedal position and the speed. 7. System for mixture metering according to one of claims 1 up to 6, characterized in that the air temperature, the air pressure and the engine temperature can be entered. - 18 109 8 42/0819. 20U633 Robert Bosch GmbHR. 9826 Sk / Sz Stuttgart 8. System for mixture dosing according to one of claims 1 to 7, characterized in that the fuel metering from the electronic function generator through a fuel metering throttle is controllable or adjustable. 9. System for mixture metering according to one of claims 1 to 7, characterized in that the fuel metering from the electronic function generator through variation the opening time of the injection valves can be controlled or regulated. 10. System for mixture dosing according to one of claims 1 to 9j, characterized in that the electronic Function generator the ignition timing as a function of adjusted to the operating parameters of the engine. 11. System for mixture dosing according to one of claims 1 to 8 and 10, characterized in that as an interlocking for fuel metering, for the throttle valve and for the ignition timing adjustment magnetic or hydraulic or pneumatic controlled with a solenoid valve Adjusters, preferably with actual value feedback, can be used. 12. System for mixture dosing according to one of claims 1 to 11, characterized in that the electronic - 19 109842/0819 • - 19 - ■■■ / ' Robert Bosch GmbH ■ ·. R * 9826 Sk / Sz Stuttgart Function transmitter the injection time as a function of controls or regulates the operating parameters of the engine. 13. System for mixture dosing according to one of claims 1 to 12, characterized in that one by an exhaust gas recirculation throttle controllable exhaust gas recirculation is provided and that the electronic Fuhktionsgeber the Exhaust gas recirculation throttle controls or regulates depending on the operating parameters of the engine. 14. System for mixture metering according to one of claims 1 to 13, characterized in that a control device is connected, which forms an actual value by measuring the nitrogen oxide or hydrocarbon content in the exhaust gases and when passing through one or more map points that for the optimal nitrogen oxide and hydrocarbon content adjusts the map to one or more specified setpoints. 15. System for mixture metering according to one of claims 1 to 14, characterized in that means for extending the spark duration, preferably to at least 0.002 seconds are provided. 16. System for mixture metering according to one of claims 1 to 15, characterized in that the electronic 109842/0819 20U633 Robert Bosch GmbH E. 9826 Sk / Sz Stuttgart Puncture transducer the excess air ratio as a function of the engine speed and the intake manifold pressure controls or regulates. 17. System for mixture metering according to one of claims 1 to 15, characterized in that the electronic Function generator depending on the excess air number controls or regulates the engine speed and the throttle valve position. 18. System for mixture dosing according to one of claims 1 to 17, characterized in that the map for lowest exhaust emission when exceeding a certain speed, z. B. 50 km / h, in the map for optimal performance or optimal fuel economy is switched. 109842/0819 Empty