DE3043326A1 - STARTING DEVICE FOR ELECTRONIC INJECTION SYSTEMS, ESPECIALLY FOR DIESEL ENGINES - Google Patents

Description

304332a

Title:

Starteinri.ch.tung for electronic injection systems, especially for diesel engines

Field of application of the invention:

The invention relates to a device for regulating the fuel injection quantity for starting conditions in electronic injection systems of internal combustion engines, in particular of Diesel engines. The device is based on a special class of electronic injection systems, the following Features:

- There is a multiplier arranged, one of the rotational speed of the crankshaft and one of the Load position-dependent voltage multiplied to a product voltage,

- In a comparison device, this is the injection time determining impulse if one taken from the crankshaft is the same, over the injection range of the angle of rotation depending on the voltage falling in the direction of rotation, triggered by the product voltage and a reference voltage and finished.

The principle of the predetermined type of electronic injection systems is described in DD-P 120 508.

Characteristic of the prior art

An injection system of the type described above and to be developed further by the invention is in DD-P 120 508 and

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126 669 described and thus previously known. The concerns of the Starting process are not taken into account in the explanations described.

It is also known from DE-OS 2 728 414 for electronically controlled fuel injection systems for internal combustion engines to provide a starting device with external ignition. This starting device extends the excitation of the electromagnetic Injection valves as a function of the coolant temperature of the internal combustion engine. The prolonged excitement is reduced depending on the time or speed. The amount of start enrichment is in a lower one Temperature range is preferably constant and is reduced with increasing temperature.

It is also previously known from DE-OS 2,743,991 electronically controlled injection systems, preferably for internal combustion engines with external ignition, a special starting circuit to be provided.

During the start circuit, which becomes effective through the start process or other parameters typical for the start, there is a large change in the amount of fuel as a function of on the temperature through a correspondingly strong extension of the time of the injection pulses. If the starting conditions are no longer applicable the start circuit becomes ineffective, and it is regulated according to a normal operating state. Here the temperature dependency of the injection quantity is severely restricted according to its actual influence on the motor operation.

A special switch is provided for changing between the start and operating status, and the alternate effective circuit arrangements for determining the Injection time switches on or off.

The starting devices described above meet the conditions not in the case of a diesel engine with regard to the variation of the injection position at combustion TDC. Likewise will the implementation of starting devices on different types of electronic injection systems is described.

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Aim of the invention:

With the present invention one of the engine temperature dependent control behavior similar to the previously known injection system for externally ignited internal combustion engines in a Injection system of the basic type mentioned at the beginning can be achieved, which is still specifically tailored to the engine requirements of the diesel engine is adapted during the starting phase.

Statement on the essence of the invention:

The invention is based on the object of providing a device for an electronic injection system as described at the beginning to regulate the fuel injection in the starting area, at the engine temperature and depending on the engine speed Injection is determined with respect to duration and position to TDC in the range below the idle speed, contrary to that other control behavior of the injection system, a temperature-dependent advanced start of injection and a temperature of the engine and its speed-dependent injection end is realized

According to the invention, the above-described object is achieved by that the input of the comparison device is preceded by a changeover switch, the first input of which with a per se known temperature voltage transmitter of the internal combustion engine is connected and at its second input directly or indirectly the output of the multiplier is connected, by means of a rotational speed detector for the motor speed controlled changeover switch in the range below the idle speed of the temperature voltage transmitter and above the idle speed range, the output of the multiplier with the input of the comparison device is connected and that the comparison device is followed by a limiting device, which from the output of the Comparison device taken injection pulse when exceeding the maximum permissible injection time or the

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maximum permissible fuel injection quantity of the internal combustion engine to be fed breaks off.

By, the solution described above is achieved that at rotational speeds below the idle range, the start of injection is completely temperature-dependent, with the Injection takes place earlier before top dead center, the lower the temperature of the internal combustion engine is. Farther the result is that the end of injection approaches top dead center with increasing rotational speed, i.e. a small amount before top dead center · This advantageous behavior is achieved by everyone The voltage associated with the temperature of the engine, which triggers the start of injection, and a limiting device, which is connected downstream of the comparison device of the injection system and the maximum injection pulse duration is limited to a constant time.

The limiting device is advantageously designed as follows:

It consists of one at the output of the comparison device connected timing element and an AND element connected equally to its input, the output of the Timing element em is connected to another input of the AND element and the injection pulse can be removed at the output of the AND element and the time constant of the timing element of the maximum permissible injection time or maximum permissible injection quantity corresponds to the internal combustion engine to be fed. According to the invention, in adaptation of the rotational speed detector to the already existing elements of the electronic injection system be implemented as follows: - A disc with pulse marks is arranged on the crankshaft or camshaft of the internal combustion engine, starting with from a constant starting position in one detected by a measuring time at the lowest idle speed There are a number of pulse marks in the area.

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- A transducer is assigned to this disk, a measuring time generator triggered by a signal from the initial position is connected to one input of an AND element; the sensor is connected to this AND element at its other input connected.

The following function groups are also available:

- a resettable binary counter, the input of which is at the output of the AND element is connected and to which a decoding circuit known per se is assigned, which is used when the counter is set of the programmed number emits a signal that is applied to the control input of the changeover switch.

In a further embodiment of the rotational speed detector, the Rucksetζimpuls for the binary counter is from the output of the Detachable measuring time generator, the trailing edge of the measuring time pulse triggers.

According to the invention, an interrupter switch can be arranged between the changeover switch and the output of the multiplier its switching path at hazardous pressure and / or temperature conditions on the internal combustion engine is open.

This circuit breaker effectively protects the motor when the temperature is too high or the lubricant pressure is too low. By disconnecting the multiplier from the comparison device, the motor can only be below the The no-load range is operated and only receives a temperature-dependent voltage, although it continues to run allows but does not allow a load operation for the engine. The temperature voltage transmitter expediently gives one Voltage from that of the injection time for the at the lowest Temperature corresponds to the required injection quantity at the lowest idle speed.

In an expedient embodiment, the temperature voltage transmitter depending on several temperatures at the motor, form the voltage it delivers.

With the latter requirement, certain valences individual thermal engine states can be taken into account in a functionally advantageous manner.

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30A3326

Embodiment:

An exemplary embodiment of the invention is to be explained with the aid of a drawing. It shows:

1 shows the basic circuit diagram of the device according to the invention for regulating the fuel injection quantity for starting conditions in connection with the control modules the type of injection system characterized at the outset.

2 shows a basic circuit diagram for the rotational speed detector adapted to the type of injection system, in which it is used.

3a-c shows the voltage diagram for IU over the injection range of 40 ° with temperature-dependent voltages U _x J ¹ ; U _x J "and an injection pulse duration limited to 4 ms, this for n _k = 500 rpm (Fig. 3a), for n _k = 300 rpm (Fig. 3b), for n _fc = 100 rpm ( Fig. 3c) of the crankshaft.

Furthermore, there are those resulting from the various voltage values of U. * and from the speeds Injection pulses 1 ^, different duration and position in Injection area shown.

Fig. 4 · a diagram for the engine temperature and Engine speed below the idle range dependent injection pulse duration t-g.

5 shows an Ira pulse plan for the device according to the invention after reaching the lowest idle speed nj-jj together with the non-equidistant pulse mark sequence I ₂ ^ i and the measuring time t _m

Construction:

In Fig. 1 is the device according to the invention for regulating the fuel injection quantity for starting conditions in connection with the electronic injection system of the above described genus. Below are the

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a

3QA3326

individual assemblies and their properties.

The pickup and pulse shaper 10 is assigned to the disk 110. This transducer 10 generates a voltage JSβ which is generated when the tooth 11 passes. The voltage IL3 of the transducer 10 corresponding to the sawtooth 11 starts with the highest voltage - initial voltage U _A and decreases linearly over the injection area λ to 0 - final voltage TJ α _e - «The voltage U ^ always has a reference value of 100 between its initial U / j _a and final voltage U / j on · The saw tooth 11 on the disk 110 extends over the injection area ß _y this is dimensioned so that at the highest crankshaft speed n ^ g ^ and maximum injection quantity V ™ ^ the injection duration t- before or after can end the top dead center.

The former 12 forms a rectangular pulse from the voltage ΙΤλ, which extends over the injection area β and is called the injection area pulse Ia

A transmitter 25 generates an increasing voltage U ₀ ^ as the accelerator pedal position increases. The load position for the internal combustion engine can be set by means of this transmitter 25. The voltage U ₀ ^ generated by it rises from a reference value O, the accelerator pedal is not actuated, to a reference value 10, at this reference value the highest load for the internal combustion engine is regulated

A disk 210, which sits on the crankshaft, is assigned to the pickup and pulse shaper 20. The pickup and pulse shaper 20 converts the pulse marks 21 on the disk 210 into square pulses I ₂ ^ with a constant width, the width of the square pulses must be less than the narrowest pulse train at the highest speed. The pulse marks 21 are arranged in a non-equidistant sequence on the disk 210 and correspond in their distribution to the injection quantity limiting characteristic _{curve VjJ 1119x of} the internal combustion engine. The voltage converter 22 converts incoming pulses I ₂ ^ in a _{constant measuring time t m into a number z m of} the detected number

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Pulses I ₂ ^ corresponding analog Winkelgesctiwindigkeitsspannung U -J _51, in the voltage converter 22 is formed with each received pulse Ί-2Λ a higher voltage, this is built up step-like and reaches the end of the measuring time t a certain value, which represents the angular velocity voltage TJ. At the crankshaft speed n ^ = O, its reference value is also O.

The voltage converter 22 is after each conversion process Can be set to O via its reset input R, as a zero setting pulse the leading edge L · of the injection area pulse acts L ·. Its output 22A is connected to the input of the memory.

The measuring time generator 23 generates the pulse I with the constant measuring time t. This measuring time t must be less than the time for one revolution of the crankshaft at the highest nominal speed. The measuring time generator 23 can be triggered via its input E, the back flank I ^ _{e of} the injection range pulse Ϊλ having a triggering effect. The gate 24 lets the pulses I ₂ ^ reach its output as long as the pulse I is present.

The memory 50, an analog value memory, holds the voltage IT present at its input 50E. _llf- when the measuring time pulse I is not present at its input H. When the measuring time pulse I is applied to the input H, the storage is interrupted, since during this time new storage takes place. The multiplier 30 multiplies the reference values of the voltages U. and IL ^ - ^, which are at its inputs 30E1 and 30E2, to a product voltage U which is present at its output 30A and, under normal operating conditions, at the input 40E3 of a comparison device 40. The multiplier 30 thus realizes the basic formula s =, ν. t. At a given time t, in the present Pall the injection pulse duration t- ,, required by the foot lever, the injection pulse angle ^ _E results from the following formula:

t _E

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In a comparison unit 40, the product voltage U formed by the multiplier 30 is compared with the voltage Πλ and plotted thereon. The multiplication of the reference values of the voltages U, and U must lead to a true statement when comparing with the reference value u through the associated angle » _E. The comparison device 40 forms the injection pulse Lg in all operating ranges, except in the area below the idle range. The inputs 40E1, 40E2 and 40E3 of the comparison device 40 are assigned a reference voltage TJ, the sawtooth voltage U / 3 and the product voltage TJ. If the sawtooth voltage IL3 and the product voltage TJ are equal, the injection pulse Ig is triggered, which can be removed from the output 40A.

If the sawtooth TJ ^ and reference voltage U, the injection pulse L ™ is terminated.

In a reference voltage generator 60, a reference voltage becomes TJ, generated · In the present application this however, it must always be constant 0, since it is irrelevant for start conditions.

To implement the starting conditions for the injection in diesel engines, a changeover switch 41 is arranged between the multiplier 30 and the comparison device 40, which below the lowest idle speed nr ^ - a temperature voltage transmitter 26 for temperature-dependent voltages - * ■ üi or U1; U1 ^M ; U1 ^tft - to the input 40E3 of the comparison device 40 turns on. Start conditions exist when the engine speed is below the idle speed range, which is limited by a lowest and a highest idle speed.

The changeover switch 41 is in turn from a rotational speed detector 28 controlled. The output 40A of the comparison device 40 is followed by a limiting device 45, the pulses emitted by the comparison device 40 when a maximum injection pulse duration is exceeded tjpax limited.

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The limiting device 45 has a timing element 42, the time constant of which is the maximum permissible injection pulse duration t-ronax of the diesel engine to be fed and its input 4-2E is connected to the output 40A of the comparison device 40. At the output 42A of the timing element 42, the input 43E2 of an AND element 43 is connected, the input of which is 43E1 is also connected to the output 40A of the comparison device 40. At the output 43A of the AND gate 43 are the injection pulses 1 ™ removable.

Furthermore, between the multiplier 30 and the Comparison device 40 next to the changeover switch 41, an interrupter switch 27 must be switched on. This breaker switch 27 is opened in the case of the internal combustion engine endangering lubricating oil pressure or engine temperatures.

Interconnection of the assemblies described above in accordance with the basic circuit diagram according to FIGS. 1 and 2.

The voltage ϋΛ generated by the sawtooth 11 in the transducer and pulse shaper 10 passes from the output 10A of the transducer and pulse shaper 10 to the input 10E2 of the comparison device 40 and to the input 12E of the shaper 12 for the injection area pulse I β . From the output 12A of the former 12 the injection area pulse Ιλ arrives at the input 23E of the measuring time generator 23 and to the clearing input 22R of the angular velocity voltage converter 22. The output 23A of the measuring time generator 23 is connected to the input 24E2 of the gate 24 and to the control input 5OH of the memory 50.

The output of the pickup and pulse shaper 20 for the Pulse marks 21 are connected to input 24E1 of gate 24. The output 24A of the gate 24 is at the input 22E of the angular velocity voltage converter 22. The output 22A of the angular velocity voltage converter 22 is connected to the input 50E of the memory 50. Of the Output 5OA of memory 50 is connected to input 3OE2 of the Multiplier 30 connected at input 30E1 of the multi

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Plierers 30 is the output 25A of the foot pedal transmitter 25 at · The output 3OA of the multiplier 30 is at the Interrupter holder 27, which is used in the case of non-motorized. Temperature- and lubrication conditions is open. The two inputs of a switch 41 are on the one hand with a Temperature voltage transmitter 26 and on the other hand with the breaker switch 27, while the output 4-1A of this switch 41 is connected to the input 40E3 of the comparison device 4-0. The switch 41 is from Rotational speed detector 28 controlled in such a way that it n- ^ the below the minimum idle speed Temperature voltage transmitter 26 connects to the input 40E3 of the comparison device 40. Above the aforementioned When the interrupter switch 27 is closed, the speed is output 30A of the multiplier 30 via the changeover switch 41 the comparison device.40 is connected. Furthermore, the reference voltage generator 60 is with his Output 6OA is connected to input 40E1 and the pulse shaper 10 is connected to input E2 of the comparison device. The output 40A of the comparison device 40 is followed by a limiting device 45, at its output no longer injection pulse I-g than with the duration t- ^ max can appear

In i "ig. 2 there is a generic type described at the beginning Circuit for the rotational speed detector 28, which builds up electronic injection systems, is shown The pulses 121 detected during the measuring time t become the Input 281E1 of an AND element 281 is supplied, with a pulse being applied to input 281E2 when the binary counter 29 is the predetermined number η during and after the measuring time t still has not achieved. The input 281E1 of the AND gate 281 is connected to the output 24A of the gate 24.

The binary counter 29 with its stages 291; 292; 293; 294 is to the AND gate 281 via the output 281A with its counting input 29IE and is connected via its reset input

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29R from the leading edge of the measuring time pulse I to zero posed.

Via a signal at the counting level outputs 293; 294 · connected AND gate 282, the final number η for recognizing the minimum idling speed n _{LK is} detected.

The AND gate 282 in turn controls the changeover switch 41 when the final number η is reached in the measuring time t and at the same time blocks the AND gate 281 for further pulses 121.

In the above-mentioned state, the switch 41 connects the multiplier 30 to the input 40E3 of the comparison device 40.

The pulse schedule for the aforementioned circuit of the rotational speed detector 28 is shown in FIG. 5.

Functionality:

In general, the mode of operation of the type of injection system of the type defined at the beginning is described in DD-P 120 508, then the concerns of the limitation of the injection quantity over the entire operating range and Abregeibbereich the highest rated speed in the documents DD-P 126 669 and 132 992 are set out.

The device according to the invention for regulating fuel injection should be below the idle range are described below:

It is characteristic of the operation below the idle range that no voltage dependent on the rotational speed of the internal combustion engine is present at input 40E3 of the comparison device 40, but a voltage U i dependent solely on the original engine temperature is connected. The effect of this is - see FIGS. 3a to 3c, all of which are shown in a time-proportional representation, that each temperature-dependent voltage U _x , ¹ ; U ^, "is assigned a specific start of injection that is independent of the crankshaft rotational speed. This is achieved by the fact that when the voltage

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and the temperature-dependent voltage XL · the injection pulse IE in the same angular position at every speed of rotation is triggered.

The individual crankshaft rotational speeds differ with engine temperatures through the constant maximum injection pulse duration t ~ the angular position of the injection end. It can be seen that with increasing rotational speed and increasing temperature the

End of injection at an injection pulse duration of t, -, ^.

is always later and thus moves closer to top dead center until the injection pulse duration t ~ is limited by the reference voltage U and then duration is shorter than

These relationships can be seen in Fig. 4, in which the effects of temperature and rotational speed of the motor on the size of the injection pulse duration t _E are shown.

The above-described behavior of the device for regulating the fuel injection quantity for starting conditions results from the primary influencing of the overall system in the low speed and temperature range by the limiting device 45 and also from the dependence of the start of injection on the engine temperature-dependent voltage U ₁ .

As the engine temperature approaches normal conditions the voltage IL becomes lower, which means that the end of injection is already through at a lower speed the reference voltage IL is determined; see Fig. 3b, compare IL "and Ir ™» ·

In FIGS. 3a-3c, the pulses Ιττ-ι »'-% 1" ^^ ^ - ^e "which occur in the injection system are shown as temperature-dependent voltages IL _t and IL _n , which means

4OA = pulse at output 4OA of comparison device 40

42A = pulse at output 42A of timing element 42 43A = pulse at output 43A of AND element 43, At the same time also injection pulse 1 ™

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The particular advantage of the device according to the invention also results from the arrangement of the limiting device 45 at the output of the computer assembly. All errors in determining the injection time that result in longer injection times than the maximum injection time "fc ^ g ^" or technical defects that have the same effect as mentioned above only result in an injection pulse of the duration tg _{ma; x: in all operating states} themselves.

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Claims (7)

Invention claims: Π J Device for regulating the fuel injection quantity for starting conditions in electronic injection systems of internal combustion engines, in which a multiplier is arranged which multiplies a voltage dependent on the rotational speed of the crankshaft and a voltage dependent on the load position to form a product voltage the pulse determining the injection time is triggered or terminated with the product voltage or a reference voltage if a voltage taken from the crankshaft and falling over the injection range depending on the angle of rotation depending on the direction of rotation is equal, characterized in that the input (4OE3) of the comparator (40) a changeover switch (4-1) is connected upstream, the first input (41E1) of which with a per se known temperature voltage transmitter (26) of the internal combustion engine is connected and at its second input (41E2) directly or indirectly the output (30A) of the multiplier (30) is connected, whereby by means of a rotation speed detector (28) for the motor rotation speed controlled changeover switch (4-1) in the range below the idle speed of the temperature voltage transmitter (26) and above the idle speed range the output (3OA) of the multiplier (30) with the Input (4ΌΕ3) of the comparison device (40) connected is and that the comparison device (40) is followed by a limiting device (45) which the from Output (40A) of the comparison device (40) taken injection pulse (t ™) when the maximum is exceeded permissible injection time (t ™ max) or the maximum permissible Injection quantity of the internal combustion engine to be fed breaks off. -16- 130035/0378 2. Iinric titung nacti point 1,
characterized, that the limiting device (4-5) consists of one at the output (4-OA) the comparison device (40) connected Timing element (4-2) and an equally connected TJETD element (4-3) with its input (4-3E1) and where the output (4-2A) of the timer (4-2) at the other input (4-3E2) of the AND element (4-3) is connected and at the output (4-3A) of the AND element (4-3) the injection?: Impuls (Lg) can be removed and the time constant (tk) of the timing element (4-2) of the maximum permissible injection time (t ^ niax) or corresponds to the maximum permissible injection quantity of the internal combustion engine to be fed. 3. Establishment according to point 1,
characterized, that the rotational speed detector (28) is formed from the following functional groups contained in the injection system: - A disc (210) with pulse marks (121) is on the Arranged crankshaft or camshaft of the internal combustion engine, starting from a constant starting position (A) in one of a measuring time (tm) at the lowest idle speed (n- ^) detected area a number (n) of pulse marks (121) are present, τ of the disk (210) is assigned to the transducer (20), a measuring time generator (23) triggered by a signal of the starting position (A) is at one input of a AND gate (24 ·) is connected to the AND gate (24-) the sensor (20) is connected to its other input, The following function groups are also available: - A resettable binary counter (29), the one per se known decoding is associated with the Counter of the number (n) emits a signal that on -17-130035 / 0378 Control input (4-1S) of the changeover switch (41) is applied, the output of the AND element (24) being connected to the input of the binary counter (29). 4. Setup according to point 3 »
characterized, that the reset pulse for the binary counter (29) from the output of the measuring time generator (23) is removable, whereby the trailing edge of the measuring time pulse (Im) triggers 5. Establishment according to point 1,
characterized, that between the changeover switch (41) and the output (3OA) of the multiplier (30) an interrupter switch (27) is arranged, the switching path in the case of hazardous pressure and / or temperature conditions on the internal combustion engine is open. 6. Establishment according to point 1,
characterized, that the temperature voltage transmitter (26) has a voltage (U ^) outputs that of the injection time (tE) for the injection quantity required at the lowest temperature at the lowest Idle speed (πτττ) corresponds to 7. Establishment according to point 1,
characterized, that the voltage (U ^) in the temperature voltage transmitter (26) is formed depending on several temperatures » 5 pages of drawings 130035/0378