WO2008000568A1

WO2008000568A1 - Method for cylinder-specific knock regulation and corresponding device

Info

Publication number: WO2008000568A1
Application number: PCT/EP2007/055126
Authority: WO
Inventors: Johannes Beer; Rainer Hannbeck Von Hanwehr; Markus Teiner
Original assignee: Siemens Aktiengesellschaft
Priority date: 2006-06-26
Filing date: 2007-05-25
Publication date: 2008-01-03
Also published as: DE102006029279B3

Abstract

According to the invention, cylinder-specific knock regulation of a petrol engine (CE) may be achieved by determining, for each cylinder (CY1 with CYn) of the petrol engine (CE), whether a knocking noise has occurred for each combustion process in the corresponding cylinder (CY1), by means of one or more knock sensors (K1 with Kn). Should a knocking noise for the current combustion process of the corresponding cylinder (CY1) be detected by the one or more knock sensors (K1 with Kn), said cylinder (CY1) with detected knocking noise is charged with a reduced air mass for the next combustion process with relation to the current combustion process during which the knocking noise was detected, by means of a dynamic air charging actuator (ILA1 with ILAn) in the inlet manifold (EK1 with EKn) thereof.

Description

description

Method for cylinder-specific knock control and associated device

In the gasoline engine, a characteristic-wide increase in the internal efficiency by increasing the compression ratio of the respective cylinder is limited by the fact that knocking combustion events can occur in the respective cylinder, especially in the upper load range of the combustion process. Details of this problem are given, for example, on the website of the Institute of Internal Combustion Engines, RWTH Aachen-52056 Aachen at http://www.vka.rwth-aachen.de/sfb_224/Kapitel/kap3_4.htm. For this reason, it is attempted via the engine control of the gasoline engine to operate its cylinder as close to the knock limit. The knock control systems used today use the ignition angle as a control variable. If knocking is detected via the knock sensor of the respective cylinder, the knocking function in the engine control unit regulates the ignition angle cylinder-individually during the next combustion process of the gasoline engine's combustion cycle "late", ie the ignition of the fuel / air mixture in this cylinder is triggered later than in the case without knocking In order to reduce the tendency to knock, the inner combustion efficiency of the gasoline engine is undesirably reduced by the combustion focus shifted in subsequent combustion processes in this cylinder.

The invention has for its object to provide a knock control for a gasoline engine with an internal engine efficiency, compared to the knock control means

Zündwinkelverlegung is improved. This object is achieved by the following method according to the invention: Method for cylinder-specific knock control of a gasoline engine with the following steps:

- For each cylinder of the gasoline engine is determined by means of one or more knock sensors, whether a knocking sound in each combustion process of this cylinder occurs;

if a knocking sound is detected by the one or more knock sensors during the current combustion process of the respective cylinder, this cylinder with detected knocking sound is detected by means of a dynamic knocking sound

Air filling actuator filled in its air inlet duct for the next combustion process of its combustion cycle with a lower air mass than for the current combustion process in which the knocking sound has been detected.

If, therefore, during the current combustion process of the respective cylinder, the one or more knock sensors on the engine block of the gasoline engine detect a knocking sound, and this knocking sound is unambiguously assigned to this cylinder, for example by means of a control device, the cylinder-specific, dynamic air-filling actuator or Actuator in the inlet channel of this cylinder with detected knocking sound before the air inlet valve controlled in such a cylinder-specific manner that for the next combustion process, ie next cycle, or for several subsequent, further combustion processes of this cylinder whose air filling is reduced with respect to the combustion process with knocking. Due to the lower cylinder filling, ie less air mass metering in the combustion chamber of the cylinder in which one or more knocking noises have been detected by the one or more knock sensors for the current combustion process, during the subsequent power stroke or combustion process or during the subsequent combustion processes a reduced compression end temperature during the Compression phase of Combustion cycle of this cylinder causes and thereby largely avoided a knocking combustion or knock tendency. By only in the respective knocking cylinder, the air charge is reduced and thus the knocking combustion is avoided in this for at least one subsequent combustion process, but cylinders that are not knocking continue to be charged with their target filling in the subsequent combustion processes, each cylinder is only with supplied so much air mass that he just does not knock. Through this cylinder-individual

Influencing the air filling of each individual cylinder with the aid of the respectively upstream, associated or specific dynamic air-filling actuator thus optimizes the internal engine efficiency of the gasoline engine as a whole. This makes it possible to set the firing angle for the combustion process of each individual cylinder to be optimal in terms of efficiency, i. It is no longer necessary to lay the firing angle for knock avoidance at a later time of the respective, next combustion process, as was previously the case.

In the context of the invention, the function and mode of action of the respective dynamic air-filling actuator can be effected in an advantageous manner by other cylinder-individual, dynamic Luftmassenzuführ- control devices or air filling plate. In general terms, therefore, a dynamic air filling actuator or air filling plate can be provided, which is cylinder-specific or cylinder-specific sufficiently fast, ie, within the time span of a combustion cycle of the respective cylinder of the internal combustion engine, the filling or metering of air mass, ie a certain amount of air in the Combustion chamber of this cylinder adapted so that knocking no longer occurs in the next power stroke of this cylinder. For example, in a 4-stroke engine corresponds to a combustion cycle substantially 720 ° crankshaft angle. For the cylinder-specific, dynamic air metering for each cylinder, its respective air inlet duct, in particular at least one impulse-loader actuator, can be specifically assigned as an air-filling actuator.

The invention also relates to a device for cylinder-specific knock control of a gasoline engine with the following components:

- For the one or more cylinders of the gasoline engine one or more knock sensors are provided for detecting a possible knocking noise during the respective combustion process of the respective cylinder; in front of the air inlet valve of the respective cylinder, a dynamic air filling actuator is provided in the air inlet duct, with which the cylinder for which the one or more knock sensors have detected a knocking sound for the current combustion process, at the next combustion process, a lower air mass than in the current Combustion cycle is supplied.

Furthermore, the invention relates to a control unit for the cylinder-specific knock control of a gasoline engine with an evaluation unit for evaluating the measurement signals of one or more knock sensors, which are attached to one or more cylinders of the gasoline engine, as to whether a knocking sound has occurred and if this is the case detected knocking sound is assigned to the cylinder with current combustion process, and with a control unit, with which the dynamic air filling actuator, which is associated with the cylinder with detected knocking noise, is controlled so that this cylinder in the next combustion process, a lower air mass as is supplied in the current combustion cycle with knocking sound occurred.

Other developments of the invention are given in the dependent claims.

The invention and its developments are explained below with reference to a single figure.

The figure shows a schematic representation

Embodiment of a gasoline engine CE with a plurality of cylinders CYl with CYn, which are knock controlled by the inventive method, in particular knock control or knock control. In particular, the gasoline engine is designed as a 2-, 4-cylinder, 6-cylinder or 8-cylinder internal combustion engine. For fresh air supply, the gasoline engine CE on a suction pipe SR. At the input end of the suction pipe SR, an air filter LF is provided, through which an air flow LM is sucked into the suction pipe. The distributor end of the suction pipe SR opens into a plurality of individual

Inlet channels EKl with EKn, that is, it is divided into each an inlet channel for each cylinder, so that each cylinder CYl with CYn each have a specific inlet channel EKl is associated with EKn. On each cylinder CYl with CYn an associated air inlet valve LIl with LIn is provided. At this ends the respective associated inlet channel EKl with EKn. The air inlet valves LIl with LIn are preferably opened by the camshaft of the gasoline engine CE expediently in a cylinder-specific manner and closed mechanically. As a result, opening and closing times are controlled or regulated individually for each air inlet valve LI1 with LIn. The camshaft has been omitted in the figure of the drawing simplicity. By means of exhaust valves of the cylinders CY1 with CYn, combustion packages can flow out of their combustion chambers into outlet channels and then into a common exhaust line of an exhaust tract AS. These exhaust valves have been omitted in the figure for the sake of clarity. The control or regulation of the opening and closing times of these exhaust valves again takes place appropriately in a mechanical manner individually, ie specifically for each exhaust valve with the aid of the camshaft of the gasoline engine CE.

In the inlet channel EKl with EKn each cylinder CYl with CYn sits between the distributor end of the common intake manifold SR and the inlet valve LIl with LIn each cylinder CYl with CYn each a pulse loader actuator ILAl with ILAn. These impulse-load actuators ILAl with ILAn serve for the pulse-like air filling of the individual cylinders CY1 with CYn, in that resonant vibration and rocking effects for the air mass flow LM in the intake pipe SR are utilized. The pulse loader actuators ILA1 with ILAn are advantageously opened at those time periods during which a pulse-type air mass flow flows through the respective inlet channel EK1 with EKn. Their control, in particular opening and closing, is carried out by a control unit CU, in particular an engine control unit, via control lines SLl with SLn. These control lines are indicated in phantom in the figure.

The entirety of the cylinders are assigned to one or more knock sensors. Thus, e.g. in a 4-cylinder gasoline engine expediently one to two

Knock sensors be arranged on the engine block. Here in the exemplary embodiment, a separate knock sensor Kl with Kn is attached to each cylinder CY1 with CYn. These knock sensors Kl with Kn are connected to the control unit CU via measuring lines ML1 to MLn. The measuring lines are shown in phantom in the figure. They continuously transmit measurement signals during the combustion cycle of the gasoline engine to the control unit CU. This evaluates the measurement signals and determines whether possibly a knocking sound has occurred during a particular cylinder during the respective combustion process. By combustion cycle of the respective cylinder is meant in particular that in an air intake phase, air is sucked into the cylinder, in a subsequent Compression phase injected fuel and the generated air / fuel mixture is ignited or instead an already prepared air / fuel mixture is introduced into the cylinder (in auto-igniters), then in a working / expansion phase, the compressed

Air / fuel mixture is expanded by burning, wherein the ignition of the air / fuel mixture can take place already in the compression stroke and / or in the expansion stroke, and finally in an exhaust phase, the burned air / fuel mixture is ejected. Generally speaking, the combustion process of a cylinder is that process during which the introduced air / fuel mixture is burned from its ignition timing to its extinction time.

Now detect the one or more knock sensors such as Kl with Kn with n = 4 knocking the current combustion process for a cylinder such as CYl the plurality of cylinders of the gasoline engine during its combustion cycle, then transmit the KnockSensoren such as Kl with Kn measuring signals Ml with Mn the control unit CU. The evaluation unit AE of the control unit CU determines from these measurement signals M1 with Mn whether and, if so, in which cylinder a knocking sound has occurred during the combustion process. In other words, the measurement signals of the plurality of knock sensors in the control unit are evaluated so that an occurring knocking sound can be uniquely assigned to a specific cylinder in an unambiguous manner. The control unit CO of the control unit CU then controls the impulse charger actuator such as ILAl, which is assigned to this cylinder such as CYL specifically with detected knocking noise, so by means of a control signal such as Sl via the associated control line such as SLL or a bus system that for the next combustion process or for the further subsequent combustion processes of this cylinder, the supplied air mass for the cylinder filling relative to the cylinder filling in the current, ie preceding combustion process is reduced. In a similar way be the air chargers actuators, in particular impulse loader actuators ILA2 with ILAn by means of control signals S2 with Sn via the associated control lines SL2 with SLn by the control unit CO of the control unit CU to a throttling, ie reducing or reducing the supplied air mass against the non-knock case for initiates future combustion events when a knock has been previously detected for their associated cylinders CY2 with CYn. In a multi-cylinder engine while the cylinder undergo their work cycles with combustion process in a predetermined order.

Due to the lower air filling of the cylinder for which a knocking sound during the current

Combustion process of its continuous combustion cycle has been detected or detected by means of one or more knock sensors, is introduced in the subsequent combustion process or in the subsequent combustion processes less air mass in the combustion chamber of this cylinder. As a result, in the next combustion process or in the subsequent combustion processes, a reduced compression end temperature is effected and thus a knocking combustion is largely avoided or a tendency to knock is reduced. By only reducing the air charge to the cylinder for the next combustion event or for the next combustion events in which a knocking sound has been detected during the current combustion process of the introduced air / fuel mixture, however, cylinders that do not knock continue with their target filling operated on air / fuel mixture, each cylinder is supplied only with so much air mass that he just does not knock. Consequently, the internal engine efficiency of the gasoline engine as a whole is optimally optimal. Zeckmäßigerweise the air mass, which is supplied to the cylinder for the next combustion process, for which a knocking sound has been detected in the previous combustion process, by at least 5%, in particular between 10% and 20%, compared to the air mass supply in the previous combustion process is reduced.

Here in the embodiment, the knock sensor serves as e.g. Kl with Kn on each cylinder, e.g. CY1 with CYn only the detection of knocking sounds in this cylinder, i. Each cylinder CYl with CYn is assigned a separate, individual knock sensor Kl with Kn for the detection of knocking. If, for example, the knock sensor K1 of the first cylinder CY1 detects a knocking noise in the combustion process of an air / fuel mixture introduced into the combustion space of the first cylinder CY1 for the current combustion process, it transmits a measurement signal to the control unit CU via the measurement line ML1. This then controls via a control line SLl the pulse loader actuator ILAl in the inlet channel EKL such that during the next combustion process of the cylinder CYL less air mass than in the current combustion process is supplied. On the other hand, the remaining cylinders CY2 with CYn whose knock sensors K2 with Kn have detected no knocking noise for them are expediently supplied with an air mass target filling which produces a desired target compression ratio in the respective cylinder, i. There is a regular air filling without reduction measures of the air mass filling instead.

With the help of the pulse loader actuators ILAl with ILAn in the inlet channels EKl with EKn, it is thus possible to cylinder CYl with CYn cylinder-specific, ie cylinder-specific to fill with air for the respective combustion cycle. Those cylinders for which no knocking sound has been detected for the current combustion process of the spark-ignition engine with the aid of the knock sensors are opened by opening as in the conventional manner and closing their individually assigned air charge actuators at appropriate times of the air mass movement LM in the intake manifold SR and adapted to the opening and closing times of the intake valves LIl with LIn targeted by a charging effect with a larger air mass filling. The one cylinder whose knock sensor has detected a knocking sound, in particular, is acted upon by a shortening of the period in which its associated air charge actuator is opened in the next combustion cycle, with a reduced mass air mass, which is less critical to a knocking in the combustion process of this cylinder. Instead of or in addition to opening and closing times, if appropriate, the flow cross-section of the respective actuator for limiting or reducing the air flow rate can be varied accordingly.

Instead of a pulse-loader actuator, it is also possible to provide another dynamic air-filling actuator or air-filling plate, which is sufficiently fast, i.e., cylinder-specific or cylinder-specific. in particular within the period of a combustion cycle of the respective cylinder of the internal combustion engine, the filling or metering of air mass, i. a certain amount of air, in the combustion chamber of this cylinder adapts so that a knock no longer occurs in the next power stroke of this cylinder. In a 4-stroke engine, a combustion cycle corresponds to substantially 720 ° crankshaft angle. In particular, can be provided as Luftbefüllungs- actuator in the air inlet passage of the respective cylinder, a Luftstellelement whose

Flow section is reduced in order to reduce the cylinder air supply to the individual, if for him in the previous combustion process "knocking" has been found.

In addition to the cylinder-specific air filling by means of the air filling actuators, it may also be appropriate be, the air mass flow LM in the intake manifold SR through a throttle valve provided there DK as a central filling plate, which is assigned to all intake ports of the cylinder together, to influence when the knock sensor at least one cylinder has registered a knocking sound during the combustion process. The throttle valve DK is connected via a control line SLD to the control unit CU. For example, the throttle valve DK can be brought into a position in which the air duct of the suction pipe SR is largely open, if an air-loader actuator or multiple air-loader actuators to knock prevention make a reduced admission with air mass of their associated knocking cylinder.

In addition, it may also be appropriate, the

Completely omit throttle valve DK and perform the filling of the combustion chamber of the respective cylinder alone with the help of the cylinder-specific air filling actuators, in particular air-load actuators ILAl with ILAn and the intake valves LIl with LIn.

Characterized in that cylinder-specific or -spezifisch with the aid of each cylinder associated air filling actuator, in particular impulse-load actuator, the amount of air is regulated in the respective cylinder when open

In order to prevent knocking of this cylinder, it can then be subjected to a reduced air mass filling independently of the other cylinders if knocking has been detected with the aid of one or more of the plurality of knock sensors. In contrast, in today's series engines no actuators are used, which allow a cylinder-specific filling control. If knocking is detected in the combustion chamber of a cylinder, so far only the ignition angle of this cylinder is corrected. With heavy knocking of individual cylinders, the air mass supply for all cylinders has hitherto been reduced jointly only by means of a central filling plate, such as a throttle flap. In contrast, the cylinder-individual influencing of the air filling of each cylinder allows a cylinder-specific knock control. By only, ie only in that cylinder with detected head noise whose combustion chamber is filled for the next combustion process with a reduced air mass, the remaining cylinders, for which by means of the knock sensors, however, no knocking sound has been determined, as previously regular with their target filling for a desired , given

Compression ratio are filled, an undesirable reduction in engine performance is largely avoided and optimizes the internal engine efficiency of the gasoline engine.

Claims

claims

1. A method for individual cylinder knock control of a gasoline engine (CE) with the following steps:

- For each cylinder (CYl with CYn) of the gasoline engine (CE) is determined by means of one or more knock sensors (Kl with Kn), whether a knocking sound during each combustion process of this cylinder (CYL) occurs; if a knocking sound is detected by the one or more knock sensors (Kl with Kn) during the current combustion process of the respective cylinder (CY1), this cylinder (CY1) is detected with detected knocking noise by means of a dynamic air filling actuator (ILA1 with ILAn) in its air Inlet channel (EKl with EKn) for the next combustion process of its combustion cycle filled with a lower air mass than for the current combustion process in which the knocking sound has been detected.

2. Method according to claim 1, wherein the dynamic air filling actuators (ILA1 with ILAn) are set with regard to their opening and closing times and / or their flow cross section for the cylinder-specific knock control of the cylinders (CY1 with CYn) by means of a control unit (CU).

3. The method according to any one of the preceding claims, characterized in that the air mass, which is supplied to the cylinder (CYL) for the next combustion, for which a knocking sound has been detected in the previous combustion process by at least 5%, in particular between 10% and 20 %, compared to the air mass feed in the previous combustion process is reduced.

4. The method according to any one of the preceding claims, characterized in that for regulating the air mass supply to each cylinder (CYl with CYn) a throttle valve (DK) in the intake manifold (SR) of the gasoline engine (CE) is additionally changed in position, if for at least one Cylinder (CYL) a knocking sound has been detected with the help of one or more knock sensors (Kl).

5. Device for the cylinder-specific knock control of a gasoline engine (CE), in particular according to one of the preceding claims, with the following components:

for the one or more cylinders (CY1 with CYn) of the

Otto engine (CE) are one or more KnockSensoren (Kl with Kn) for detecting any knocking noise in the respective combustion process of the respective cylinder (CYl provided - in front of the air inlet valve (LIl with LIn) of the respective

Cylinder (CYl with CYn) is in its air inlet channel (EKl with EKn) a dynamic air filling actuator (ILAl with ILAn) provided with the cylinder (CYL), for which the one or more knock sensors (Kl) for the current Combustion detected a knocking sound, the next combustion process, a lower air mass is supplied as in the current combustion cycle.

6. The device according to claim 5, characterized in that a dynamic charge actuator (ILAl with ILAn) in the air inlet duct ((EKl with EKn) of the respective cylinder (CYl with CYn) is provided as a dynamic air filling actuator.

7. Device according to one of claims 5 or 6, characterized in that a control unit (CU) for adjusting the dynamic air filling actuators (ILAl with ILAn) is provided such that only the one cylinder (CYL) is detected with detected knocking noise in the current combustion process for the next combustion process with a reduced air mass, while the remaining cylinder (CY2 with CYn), for which the one or more knock sensors (K2 with Kn) have detected no knocking sound, are each acted upon with their target filling in air mass.

8. Device according to one of claims 5 to 7, characterized in that the air inlet ducts (EKl with EKn) of the cylinder (CYl with CYn), in which the dynamic air filling actuators (ILAl with ILAn) are arranged at the distributor end of the intake manifold (SR ) of the gasoline engine (CE).

9. The device according to claim 8, characterized in that the suction pipe (SR) has a throttle valve (DK), which is additionally brought to influence its total air mass flow (LM) in a changed position when using one or more knock sensors (Kl with Kn ) a knocking sound has been detected during the respective combustion process of the respective cylinder (CY1).

10. Control unit (CU) for the cylinder-specific knock control of a gasoline engine (CE), in particular according to one of claims 1 to 4, with an evaluation unit (AE) for evaluating the measurement signals (Ml with Mn) one or more knock sensors (Kl with Kn), the are attached to one or more cylinders (CY1 to CYn) of the gasoline engine (CE), as to whether a knocking sound has occurred and, if so, that this detected knocking sound is attributed to the cylinder with current combustion and to a control unit (CO ), with which the one dynamic Air filling actuator (ILAl with ILAn), which is assigned to the cylinder (CYL) with detected knocking noise is controlled so that this cylinder (CYL) is supplied during the next combustion process, a lower air mass than in the current combustion cycle with a knocking sound.