DE102015203756B4 - Method and device for adjusting a Zündwinkeleingriffes on an internal combustion engine - Google Patents

Abstract

A method for adjusting an ignition angle intervention on an internal combustion engine, wherein a knocking combustion is detected and due to the knocking combustion of a later, characterized by an ignition angle ignition timing is reacted by a knock control with a predetermined Zündwinkelrückzuggebetrag on the knocking combustion, the ignition to the angle is added, characterized in that at a rapidly changing load profile first occurring knock events are not acted upon by the full Zündwinkelrückzugsbetrag by the predetermined Zündwinkelrückzuggebetrag is reduced upon activation of the knock control.

Description

State of the art

The invention relates to a method for setting a Zündwinkeleingriffes on an internal combustion engine, in which a knocking combustion is detected and due to the knocking combustion, a later, characterized by a firing angle ignition is given, which is reacted with a predetermined Zündwinkelrückzugungsentong the knocking combustion, the Ignition angle is added.

From the DE 43 00 929 C1 Already a knock control with a short time constant and a long time constant is known.

In internal combustion engines, it is common to detect the knocking by means of a knock sensor. This knock sensor is arranged on the internal combustion engine and detects structure-borne sound vibrations of the internal combustion engine, which arise as a result of explosive burns within the cylinder of the internal combustion engine. Such, within the combustion chamber of the internal combustion engine resulting explosive burns are converted into vibrations, which are forwarded to the wall of the engine and perceived there as a structure-borne noise. Excessively high vibrations can damage the internal combustion engine and must therefore be prevented.

For this purpose, a knock detection as part of an engine control unit function evaluates the signals of the knock sensor to detect knocking burns of the internal combustion engine. If a knocking combustion is detected, a later ignition point in the form of a defined ignition angle is specified for the next combustion in order to avoid further knocking burns. This process is called knock control. In the application phase of the knock control, various parameters of the knock detection and knock control are specified. These include the duration and amount of firing retraction in response to the knocking combustion. A determination of such parameters usually takes place on an engine test bench, in which stationary engine conditions are set during the design of the parameters.

In contrast to these stationary conditions on the engine test bench, relatively fast changing load profiles often occur in real driving scenarios of a vehicle. For example, vehicles in urban or interurban traffic are often accelerated for a short time and then operated in relatively low load ranges or there is a change of acceleration and deceleration. The disadvantage here is that a knocking event is detected in the relatively short full load phases, to which the knock control by the ignition angle retreatment by the amount specified during the application responds, although the engine is often operated only for a short time in a range in which a knocking occur can. This has the consequence that a complete compensation of the ignition angle retreat often does not occur.

Disclosure of the invention

The invention has for its object to provide a method in which is responsive to rapidly changing load profiles during the real drive of the motor vehicle by the knock control.

According to the invention the object is achieved in that the predetermined ignition angle retraction amount is reduced upon activation of a knock control. Thus, upon entering the knock control active area in the first knock events that occur, it does not react with the full firing angle retraction amount. As a result, with only a short increase in load and associated knocking, the ignition angle is reset by a smaller amount but sufficient for safe engine operation. This has the advantage that a lesser Zündwinkeleingriff sufficient to prevent knocking of the internal combustion engine during the real drive of the motor vehicle. The lower ignition retraction improves the efficiency and driveability characteristics of the internal combustion engine while driving.

Advantageously, the reduction of the ignition angle retraction amount takes place as a function of the occurrence of a knock signal. This ensures that this measure is only realized when the actual knock event occurs.

In one embodiment, the reduction of the Zündwinkelrückzuggebetrages is withdrawn until after a defined number of knock events, the full Zündwinkelrückzuggebetrag is reached again at each further knock event. Thus, it is ensured that only when the internal combustion engine is operated at the knock limit for a longer time, i. several knock events have occurred, the stationary applied Zündwinkelrückzugbetrag is applied.

In one variant, the reduction of the ignition angle retraction amount takes place on a time-based basis. This ensures that a stationary combustion engine actually realizes the firing angle retractions defined during the application.

In one embodiment, the ignition angle retraction amount is determined as a function of a stationary operating point of the internal combustion engine and considered to be constant for this operating point. Thus, the proposed method is based on a constant ignition angle retraction amount, which was designed under stationary conditions of the internal combustion engine.

Such an ignition angle retraction amount is determined in an application phase of the knock control of the internal combustion engine, taking account of the load and speed of the internal combustion engine.

In a further variant, the ignition angle retraction amount is stored in a map which is the basis of the knock control. The knock control accesses the ignition angle retraction amount corresponding to the respective operating point in order to correspondingly adjust the ignition angle representing the ignition point. A smaller ignition angle retraction amount improves the efficiency and driveability characteristics of the internal combustion engine.

A development of the invention relates to a device for setting a Zündwinkeleingriffes on an internal combustion engine, which receives signals from a structure-borne sound sensor and outputs a function of these signals a later, represented by an ignition angle ignition timing on the engine to which a predetermined Zündwinkelrückzugsbetrag can be added. A device which reacts dynamically to the current load profiles of a real driving scenario of a vehicle comprises means which reduce the predetermined ignition angle retraction amount upon activation of a knock control. Thus, when the first knock events occur, it does not react with the full ignition angle retraction amount. Only when the internal combustion engine is operated at the knock limit for a longer time, the stationary applied ignition angle retraction amount is applied.

Advantageously, the means reduce the ignition angle retraction amount as a function of a knocking event and / or a time-based event.

The invention allows numerous embodiments. One of them will be explained in more detail with reference to the figures shown in the drawing.

• 1 Vorrichtung zur Erfassung von Klopfsignalen in einem Verbrennungsmotor,
• 2 ein Ausführungsbeispiel für das erfindungsgemäße Verfahren.

Show it:

• 1 Device for detecting knock signals in an internal combustion engine,
• 2 an embodiment of the inventive method.

1 shows a device for detecting knock signals with an internal combustion engine. The internal combustion engine 1 has four cylinders in this example 2 . 3 . 4 . 5 on, whose piston not shown, which is in the cylinders 2 . 3 . 4 . 5 move, each with a connecting rod 6 . 7 . 8th . 9 with the crankshaft 10 are connected and drive them due to the pressure changes caused by the combustion. The cylinders 2 . 3 . 4 . 5 are with a suction tube 11 connected by a throttle 12 opposite an air intake pipe 13 is completed. In every cylinder 2 . 3 . 4 . 5 protrudes a nozzle 14 for injection of fuel and an intake valve 15 for the fresh air, resulting in the cylinder 2 . 3 . 4 . 5 forms a fuel-air mixture. In addition, each cylinder has 2 . 3 . 4 . 5 an outlet valve 16 for the exhaust gases that arise during the combustion processes.

At the internal combustion engine 1 is a structure-borne sound sensor 17 arranged, which caused by the combustion and the internal combustion engine 1 transmitted structure-borne sound vibrations detected. The signals of the structure-borne sound sensor 17 be sent to a controller 18 forwarded, which also with one of the crankshaft 10 opposite crankshaft sensor 19 is connected, wherein the control unit 18 the burns the signal of the crankshaft sensor 19 assigns, which presents a crankshaft angle. The control unit 18 includes a microprocessor 20 that with a memory 21 connected is. In the store 21 is a map 22 stored, which depends on the knock strength vir_kr and the rotational speed n of the internal combustion engine 1 emits a retard angle in response to knocking burns.

This in 2 shown map 22 is in an application of the internal combustion engine 1 at stationary conditions of the internal combustion engine 1 determined, wherein the stationary engine conditions are generated on a test bench. In this application, knock detection and knock control parameters such as duration and spark retraction amount are set in response to knocking combustion. On, off the map 22 applied ignition angle retraction amount is speed dependent and constant for a fixed speed. At a constant operating condition of the internal combustion engine 1 is the from the map 22 taken Zündwinkelrückzuggebetrag of, for example, 3 ° for retarding the combustion in the internal combustion engine 1 used to minimize or completely suppress knock events.

How out 2 can be seen, first occurring knock events are not charged with the full ignition angle retraction amount for the retardation of the combustion when the internal combustion engine 1 works in the current motor vehicle due to relatively fast changing load profiles in different operating points. Such an intervention in the stationary ignition angle retreat occurs when the active range of the knock control B_kr is activated, which means that the corresponding bit in a software control is set from 0 to 1. If this is the case, then an applicable reduction amount ZW_red is initialized, which is for example -1.5 °. Now occurs a knocking event B_kl On, the ignition angle retraction amount is reduced by this applied reduction amount of -1.5 °. Thus, the effective ignition angle retraction amount is 3 ° - 1, 5 ° = 1, 5 °. As a result, the full firing angle retraction amount does not respond to the knock event. With each further knocking event, which by the bit B_kl is displayed, the reduction is in the point 23 taken back, for example, the value of 1, 5 ° -0.75 ° = 0.75 °. 3 ° -0.75 ° results in a retardation of the crankshaft angle of 0. With each further knock event, the Zündwinkelrückzuggebetrag is closer to that from the map 22 amount withdrawn from 3 °. At the next knock event, the reduction of the ignition angle retraction amount is made by a further -0.75 °. This is done after each knock event until the ignition angle retraction amount of 3 ° applied in the map is reached, in the described case after two further knock events. This ensures that complete compensation of the ignition angle retraction takes place in each control cycle. The knock associated with the short-term increase in load is retarded at a firing angle by a smaller amount but sufficient for safe engine operation.

Such a procedure also has a positive effect in the event of a possibly existing error detection tendency in the knock control, since the ignition angle retraction engagement is reduced when it enters the active range of the knock control, which thus has no major effect on the engine control.

In addition to the withdrawal of the occurrence of a knock event B_kl can also be a time-based redemption. This ensures that the ignition angle retraction amount determined during the application is reliably realized when the internal combustion engine 1 works in the region of the knocking condition.

Claims (9)

A method for adjusting an ignition angle intervention on an internal combustion engine, wherein a knocking combustion is detected and due to the knocking combustion of a later, characterized by an ignition angle ignition timing is reacted by a knock control with a predetermined Zündwinkelrückzuggebetrag on the knocking combustion, the ignition to the angle is added, characterized in that at a rapidly changing load profile first occurring knock events are not acted upon by the full Zündwinkelrückzugsbetrag by the predetermined Zündwinkelrückzuggebetrag is reduced upon activation of the knock control. Method according to Claim 1 , characterized in that the reduction of the Zündwinkelrückzuggebetrages takes place in dependence of the occurrence of a knock signal. Method according to Claim 2 , characterized in that at each further knock event, the reduction of Zündwinkelrückzuggebetrages is partially withdrawn until after a defined number of knock events, the full Zündwinkelrückzuggebetrag is reached again. Method according to Claim 1 , characterized in that the reduction of the ignition angle retraction amount is time-based. Method according to at least one of the preceding claims, characterized in that the ignition angle retraction amount is determined as a function of a stationary operating point of the internal combustion engine (1) and is considered to be constant for this operating point. Method according to Claim 5 , characterized in that the ignition angle retraction amount in an application phase of the knock control of the internal combustion engine (1) is determined. Method according to Claim 6 , characterized in that the ignition angle retraction amount in a map (23) is stored, which is based on the knock control. Device for setting a Zündwinkeleingriffes on an internal combustion engine, which receives signals from a structure-borne sound sensor (17) and in response to these signals by a knock control a later, characterized by an ignition angle ignition timing on the internal combustion engine (1), to which a predetermined Zündwinkelrückzuggebetrag is added, characterized characterized in that means (20, 21) are provided which do not apply to the full Zündwinkelrückzuggebetrag first occurring at a rapidly changing load profile knock events by reducing the predetermined Zündwinkelrückzuggebetrag upon activation of the knock control. Device after Claim 8 , characterized in that the means (20, 21) the Zündwinkelrückzuggebetrag in dependence of a Reduce the knocking event and / or a time-based event.

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