EP0638717A2 - Apparatus for controlling the fuel injection and the ignition of a combustion engine - Google Patents

Abstract

A device for controlling the fuel injection and the ignition in an internal combustion engine is described, in which the position of the crankshaft and camshaft is determined in the control module as soon as possible after switching on the internal combustion engine. For this purpose the output signals of a crankshaft and a camshaft sensor are evaluated, the crankshaft sensor detecting at least one reference mark and the camshaft sensor having a sensor disc, which has a marking, which extends over an angle of 180 DEG . The co-ordination between crankshaft and camshaft must be such that the change in the level of the camshaft sensor signal is situated as precisely as possible between two reference marks. It is then possible to produce four marks, which are used to transmit the first injection and ignition signals, it being possible to run additional plausibility checks. <IMAGE>

Description

State of the art

The invention relates to a device for regulating fuel injection and ignition in an internal combustion engine according to the preamble of the main claim.

In multi-cylinder internal combustion engines with electronically controlled injection and ignition, the control unit usually calculates when and how much fuel should be injected per cylinder and when the appropriate ignition timing is. In order that these calculations can be carried out correctly, the respective position of the crankshaft or camshaft of the internal combustion engine must be known. It is therefore common and is described, for example, in EP-A1 0 371 158 that the crankshaft and the camshaft are included one disc each are connected, a single marking is arranged on the surface of the disc connected to the crankshaft, while on the upper surface of the disc connected to the camshaft there is a marking which extends over an angle of 180 °.

The two rotating disks are scanned by suitable fixed sensors, from the chronological sequence of the pulses supplied by the sensors, a clear statement about the position of the crankshaft and camshaft is obtained, depending on which control signals for injection and ignition are generated in the control unit.

In the known device, the injection takes place for the first time as a function of the camshaft sensor signal into the cylinder group, which predominantly has closed intake valves. The injection for the next cylinder group is placed on the level change of the camshaft signal or sequentially after the synchronization.

The known device has the disadvantage that the first injections take place with undefined advance angles and a large number of injections take place at an early point in time when the fuel pressure build-up phase has not yet been completed.

In order to reduce these problems during the starting phase, a device for detecting the position of at least one shaft having a reference mark is therefore described in the as yet unpublished German patent application P 42 30 616. This device is used in an internal combustion engine. In this case, after the ignition and injection have been switched off, an end-of-run detection is carried out, the position of the crankshaft and camshaft being determined and stored by the control unit at a standstill.

When switched on again, the positions determined in this way are immediately available to the control unit, so that the first injections can take place shortly after the start of rotation. In this known device, however, an overrun detection must always be carried out.

Advantages of the invention

The inventive device with the features of claim 1 has the advantage that the position of the crankshaft and camshaft can be determined particularly quickly, so that a very early start of sequential injection is possible. The first injections take place at a defined pre-storage angle and at the latest possible time, so that these injections take place at a largely secure fuel pressure. In addition, reliable phase-correct cylinder detection and ignition output are obtained after a particularly short rotation angle, so that short starting times result.

These advantages are achieved by arranging a phase sensor disk with a 180 ° mark on the camshaft, which is scanned with a satin pickup, while at the same time there is a crankshaft sensor disk with 60-2 markings and a reference mark and the disks are arranged such that the level change of the camshaft sensor disk takes place as precisely as possible between two reference marks.

Further advantages of the invention are achieved by the measures specified in the subclaims.

drawing

The invention is illustrated in the drawing and is explained in more detail in the following description. 1 shows a rough overview of the arrangement of the crankshaft or camshaft together with the associated sensors and the control unit, in which the calculations for regulating the injection and ignition run. In Figure 2 control signals or signals emitted by sensors are plotted over time during the starting phase of an internal combustion engine.

Description of the embodiment

In Figure 1, the components of an internal combustion engine required to explain the invention are shown by way of example, 10 being an encoder disk which is rigidly connected to the crankshaft 11 of the internal combustion engine and has a multiplicity of similar angular marks 12 on its circumference. In addition to these similar angle marks 12, a reference mark 13 is provided, which is realized, for example, by two missing angle marks.

A second encoder disk 14 is connected to the camshaft 15 of the internal combustion engine and has a mark 16 on its circumference which extends over an angle of 180 °. At 17, the connection between the crankshaft and camshaft, which rotates the camshaft at half the crankshaft speed, is symbolically represented.

The two encoder disks 10, 14 are scanned by sensors 18, 19, for example inductive sensors or Hall sensors, for example static Hall sensors, the signals generated when the angular marks pass in the sensors are either processed in the same way and fed to a control unit 20 or only in Control unit 20 is prepared in a suitable manner, preferably square wave signals are formed, the rising edges of which correspond to the start of an angle mark and the falling edges of which correspond to the end of an angle mark. These signals or the time sequences of the individual pulses are evaluated in the control unit.

Regarding the arrangement of the two encoder disks, it should also be noted that it must be carried out in such a way that the encoder disk connected to the camshaft, which in the associated sensor generates a signal with equally large low and high phases, results in a level change between low and High falls as precisely as possible between the reference mark signals supplied by the crankshaft encoder.

The control unit 20 receives, via various inputs, further input variables required for the control or regulation of the internal combustion engine, which are measured by various sensors. Examples of such sensors may be mentioned: a temperature sensor 21, which measures the engine temperature, a throttle valve sensor 22, which registers the position of the throttle valve, a pressure sensor 23, which measures the pressure in the intake pipe or the pressure in a cylinder of the internal combustion engine. Furthermore, an "ignition on" signal is supplied via the input 24, which is supplied by the terminal Kl.15 of the ignition lock when the ignition switch 25 is closed.

On the output side, the control unit, which includes computing or storage means (not shown) and a permanent storage designated 30, provides signals for the ignition and injection, for corresponding components of the internal combustion engine, not specified. These signals are emitted via the outputs 26 and 27 of the control unit 20.

Depending on requirements, further sensors can be used, the signals of which are fed to the control unit, and the control unit 20 can also emit further signals required for regulating the internal combustion engine. It is not absolutely necessary that all of the sensors shown are present.

The control unit 20 is supplied with voltage in the usual way with the aid of a battery 28, which is connected to the control unit 20 via a switch 29 during operation of the internal combustion engine and, in a further embodiment, during a run-on phase after the engine has been switched off.

With the device described in Figure 1, the position of the crankshaft 11 and the camshaft 15 can be detected at any time during operation of the internal combustion engine, since the assignment between the crankshaft and the camshaft is known as well as the assignment between the position of the camshaft and the position of the individual cylinders , After the reference mark has been recognized, synchronization can take place and, after synchronization has taken place, the injection and the ignition can be controlled or regulated in a known manner. Such control or regulation of an internal combustion engine is described for example in DE-OS 39 23 478 and is therefore not explained in detail here.

With the device described in FIG. 1, with the addition according to which the control unit 20 is also supplied with voltage even in a run-on phase, it is also possible to detect the motor position during the run-down, that is to say during the so-called run-on phase. In this follow-up phase, which follows the normal operation of the internal combustion engine, for example described in the above-mentioned laid-open publication, the sensor output signals are still evaluated. The last positions of the crankshaft and camshaft determined in this way are stored in the permanent memory 30 of the control unit 20 and are therefore immediately available when switched on again. The exact procedure for this is described in DE-P 42 30 660 and is therefore not explained in more detail here.

For a 5-cylinder internal combustion engine, the signal or voltage profiles U (t) [V] which are essential for understanding the invention and which were recorded during test runs are plotted over time t in milliseconds in FIG.

The starting conditions are, for example:
Fig 2: Injection pre-storage: 30 ° KW after LWOT Starting position: 48 ° KW before OT1 First injection after: 150 ° KW First ignition after: 480 ° KW Start of ramp-up after: 480 ° KW
Fig 3: Injection pre-storage: 72 ° KW after LWOT Starting position: 60 ° KW before OT3 First injection after: 54 ° KW First ignition after: 348 ° KW Start of ramp-up after: 348 ° KW
Fig 4: Injection pre-storage: 102 ° KW according to LWOT Starting position: 72 ° KW before OT4 First injection after: 96 ° KW First ignition after: 360 ° KW Start of ramp-up after: 360 ° KW
Fig 5: Injection pre-storage: + 6 ° KW before LWOT Starting position: 54 ° KW before OT5 First injection after: 120 ° KW First ignition after: 474 ° KW Start of ramp-up after: 474 ° KW With OT1 to OT 5 the top dead center of cylinders 1 to 5 is designated.

FIG. 2a shows the control signals A, B, C, D and E emitted by the control unit for the injection valves EV1 to EV5, the injections being characterized by the minima. The hatched areas indicate the first injection. The area X denotes a phase during which an intake valve is open. The first firings that take place in the individual associated cylinders are symbolized by an arrow.

In Figure 2b, the upper signal F indicates the course of the output signal of the camshaft sensor or the phase sensor, with this signal a phase change occurs every 360 ° KW with the selected sensor disk. The first edge change is referred to as the M1 mark. The lower signal G shows the course of the ignition signals.

The speed signal H and the output signal J of the crankshaft encoder are plotted in FIG. 2c, indicated for a corresponding encoder disk with a multiplicity of angular marks of the same type and a reference mark represented by two missing angular marks.

At time t1, the start of the internal combustion engine is initiated via the ignition lock 25. The control unit 20 applies voltage to the individual systems or transmitters, and the electric fuel pump relay is actuated, so that the fuel pump begins to deliver the fuel.

At this point in time, the control unit is usually not yet aware of the exact angular position of the crankshaft or camshaft. However, if a run-on detection is carried out as described in German patent application P 42 30 616, the exact angular position is already known at this point in time and the control unit can immediately start calculating the times that are important for the injection.

At time t2, the starter is engaged and the engine begins to turn, the crankshaft sensor emits speed-dependent pulses.

FIGS. 3 to 5 show the same situation as in FIG. 2, but with a different starting position of the engine and thus also with different injection angles.

The reference mark BM can be seen in the output signal of the crankshaft sensor in FIGS. 3c and 5c, it corresponds to a mark designated as mark M2 or M4. In FIG. 4c, the mark M3 is determined by the first edge change of the camshaft sensor signal.

• 1. Mit der Bezugsmarke und dem Pegelwechsel des Phasensignales von Low nach High und von High nach Low ergeben sich über ein Arbeitsspiel von 720°KW die vier Marken M1 bis M4, an denen die Einspritzung synchronisiert beginnt. Entsprechend der Motorposition werden an den Marken die ersten Einspritzungen derart abgesetzt, daß ein schneller und sicherer Start möglich ist. Die ersten Einspritzungen sind in den Figuren 2 bis 5 schraffiert dargestellt.
  Der Zylinder, der mit der ersten Einspritzung an den Marken bedient wird, ist motortemperaturabhängig wählbar. Um einen schnellen Start zu erreichen sind kleine Vorlagerungswinkel und gegebenenfalls sogar Einspritzungen ins offene Einlaßventil erforderlich, sofern eine ungünstige Zündkerzenlage oder sehr große Einspritzzeiten dies nicht verbieten. Gleichzeitig mit der ersten Einspritzung oder kurz danach erfolgt eine zweite Einspritzung in den nächstfolgenden Zylinder.
  Die weiteren Einspritzungen erfolgen sequentiell im nächsten Segment. Diese schließen sich an die Einspritzungen an den Marken derart an, daß fehlende oder doppelte Einspritzungen nicht auftreten.
• 2. Um eine sichere zylinderrichtige Zündausgabe durchzuführen, erfolgt diese erst nach dem Erkennen der Bezugsmarke und des Phasenwechsels. Es wird also geprüft, ob das Phasensignal in Ordnung ist. Die Reihenfolge, in der diese Signale auftreten, ist beliebig. Die genannte Vorgehensweise ist besonders bei 5-Zylinder-Motoren wegen der dort herrschenden Unsymmetrie erforderlich.
• 3. Um eine besonders schnelle Zündausgabe durchzuführen, erfolgt diese nach dem Erkennen des Phasenwechsels oder nach der Bezugsmarke. Eine Überprüfung, daß das Phasensignal in Ordnung ist, erfolgt dann für die ersten Zündungen nicht. Diese Vorgehensweise ist bei 4-, 6-, 8-, 12-Zylindermotoren zulässig.
  Da sich die Zündausgabe an den Pegelwechsel des Phasensignals anschließt, muß die genaue Lage dieser Marke bekannt sein. Die Bestimmung dieser Marke kann durch ein geeignetes Adaptionsverfahren im Start oder Leerlauf erfolgen.
  In Kombination mit einer frühzeitigen Einspritzung mit Vorabspritzern oder einer Einspritzung nach durchgeführter Auslauferkennung, sind besonders schnelle Starts möglich. Vorabspritzer sind dabei Einspritzungen, die vor der Synchronisation in alle Zylinder gleichzeitig erfolgen. Erste sequentielle Einspritzungen, die auch noch vor Drehbeginn erfolgen können, sind nur in Verbindung mit einer Auslauferkennung oder einem Absolutgebersystem möglich, da in diesen beiden Fällen die genaue Motor- bzw. Wellenstellung bereits unmittelbar nach dem Start bekannt sind.
• 4. Mittels der Pegelwechsel des Phasensignales ist auch eine Verstellwinkelerfassung bei einem System mit einer variablen Nockenwellenverstellung möglich oder es ist eine Diagnose bei einer Nockenwellensteuerung möglich.

Based on the arrangement according to FIG. 1 and the signal curves shown in the following figures, it will now be explained how the injection and ignition output takes place at the start using the marks M1 to M4.

• 1. With the reference mark and the level change of the phase signal from low to high and from high to low, the four marks M1 to M4, at which the injection begins synchronized, result over a working cycle of 720 ° KW. According to the motor position The first injections are deposited on the brands in such a way that a quick and safe start is possible. The first injections are shown hatched in FIGS. 2 to 5.
  The cylinder that is operated with the first injection at the brands can be selected depending on the engine temperature. In order to achieve a quick start, small pre-storage angles and possibly even injections into the open intake valve are required, provided an unfavorable spark plug position or very long injection times do not prohibit this. Simultaneously with the first injection or shortly thereafter, a second injection into the next cylinder follows.
  The further injections take place sequentially in the next segment. These follow the injections on the brands in such a way that missing or double injections do not occur.
• 2. In order to carry out a safe cylinder-correct ignition output, this takes place only after the reference mark and the phase change have been recognized. It is therefore checked whether the phase signal is OK. The order in which these signals occur is arbitrary. This procedure is particularly necessary for 5-cylinder engines because of the asymmetry there.
• 3. In order to carry out a particularly rapid ignition output, this takes place after the phase change has been recognized or after the reference mark. A check that the phase signal is OK is then not carried out for the first firings. This procedure is permissible for 4-, 6-, 8-, 12-cylinder engines.
  Since the ignition output follows the level change of the phase signal, the exact location of this mark must be known. This mark can be determined by a suitable adaptation process in the start or idle.
  In combination with an early injection with pre-spraying or an injection after the end-of-run detection, particularly fast starts are possible. Pre-splashes are injections that occur in all cylinders simultaneously before synchronization. The first sequential injections, which can also take place before the start of rotation, are only possible in conjunction with a run-out detection or an absolute encoder system, since in these two cases the exact motor or shaft position is known immediately after the start.
• 4. By changing the level of the phase signal, an adjustment angle detection is also possible in a system with a variable camshaft adjustment, or a diagnosis is possible with a camshaft control.

Claims (8)

Device for controlling the fuel injection and ignition in an internal combustion engine with a computing device in which the angular position of the crankshaft and the camshaft is determined by evaluating the corresponding sensor signals for forming control signals for the injection valves and for triggering ignitions, characterized in that for Determining the position of the camshaft, a disk connected to the camshaft is scanned which has an angle mark extending over 180 °, that a reference mark is present on the crankshaft or a disk assigned to the crankshaft and the crankshaft and the camshaft are assigned to one another in such a way that the level change of the camshaft sensor signal occurs approximately in the middle between two reference marks. Device according to claim 1, characterized in that the computing device is the control device of the internal combustion engine. Device according to one of the preceding claims 1 or 2, characterized in that a mark M1 to M4 is formed from the reference mark of the crankshaft sensor signal and an edge change of the camshaft sensor signal, which are used to form the injection and / or ignition signals. Device according to one of the preceding claims 1 to 3, characterized in that in particular when the engine is started, first injections at the marks (M1 to M4) into certain cylinders, which can be selected as a function of the temperature, take place in such a way that short starting times are achieved. Device according to one of the preceding claims, characterized in that the first ignition outputs take place only when the reference mark and a phase change have been recognized, the sequence of the occurrence of the corresponding signals being disregarded. Device according to one of the preceding claims 1 to 3, characterized in that the first ignition outputs already take place after the detection of a phase change or after the reference mark without prior checks if this is permissible for certain numbers of cylinders. Device according to one of the preceding claims, characterized in that after the synchronization there is a transition to a customary cylinder-specific injection without incorrect or double injections, in particular the so-called SEFI. Device according to one of the preceding claims, characterized in that the control device comprises means which, after switching off the ignition of the internal combustion engine, evaluates the transmitter signal or the transmitter signals until the crankshaft and camshaft come to a standstill and the crank position thus determined - and saves the camshaft at standstill and makes it available when it is switched on again.

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