EP2659117A1

EP2659117A1 - Method for operating an injection system for an internal combustion engine

Info

Publication number: EP2659117A1
Application number: EP11781529.0A
Authority: EP
Inventors: Andreas Posselt; Marko Lorenz; Andreas Gutscher
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-12-27
Filing date: 2011-11-09
Publication date: 2013-11-06
Also published as: DE102010064184B4; KR20140004111A; CN103282630B; RU2013135114A; CN103282630A; BR112013016312A2; BR112013016312B1; WO2012089389A1; JP5833138B2; KR101869234B1; JP2014501348A; DE102010064184A1; US20130340719A1

Abstract

The invention relates to a method for operating an injection system for an internal combustion engine comprising a combustion chamber, wherein in a first method step a first inlet valve to the combustion chamber is opened, and a first injection valve injects fuel through the opened first inlet valve into the combustion chamber. Furthermore, in the first method step, a second inlet valve to the combustion chamber is opened, and a second injection valve injects fuel into the combustion chamber through the opened second inlet valve. In a second method step, additional fuel is injected by the first injection valve into the combustion chamber through the still open first inlet valve.

Description

Description title

Method for operating an injection system for an internal combustion engine State of the art

The invention relates to a method according to the preamble of claim 1. Furthermore, the invention relates to a computer program and a storage medium.

Such injection systems for internal combustion engines are well known. For example, the document DE 10 2008 044 244 A1 discloses an internal combustion engine having at least one combustion chamber, wherein the combustion chamber has two fuel inlet openings, which can each be closed by an inlet valve. The internal combustion engine also has a fuel injection device which, in association with the at least one combustion chamber, has a first and a separate second injection valve for the metered injection of fuel into at least one intake passage of the combustion chamber. The injectors spray the fuel while atomized in the form of spray cones in the direction of the intake valves.

Furthermore, it is known from the prior art to calculate the fuel quantity required in future by means of load prediction methods and to correspondingly control the injection valve for injecting the calculated amount of fuel into the intake manifold. The injection of the fuel takes place in internal combustion engines with intake manifold injection, however, usually time before the intake stroke. If the throttle valve suddenly opens sharply after the injection, for example because the driver of the motor vehicle requests an increased torque, more air flows into the combustion chamber than was originally assumed in order to calculate the required fuel quantity. Since the injection process is already completed at this time, the amount of fuel can be No longer be adapted to the larger amount of air, so that the air-fuel mixture is emaciated in the combustion chamber and thus there is the danger of a power dip to misfiring. This problem is solved in that a re-injection of additional fuel is carried out while the inlet valve is still open. Such an approach is known for example from the publications DE 103 48 248 A1 and DE 10 2004 004 333 A1. This has the disadvantage, however, that only a very small amount of fuel has to be injected in each cycle during the refilling process in comparison to the first-time injection process. The size of the flow rate of an injection valve, however, at the same time determines the smallest quantity which can still be delivered with a corresponding accuracy. The known from the prior art injection valve, which is usually designed for the injection of larger amounts of fuel, may therefore be connected only for a very short duration, whereby a large relative deviation from the calculated target value of the amount of injected fuel. Furthermore, there is a risk that the injection valve will operate in a non-linear range due to the short switch-on pulse, which further increases the deviation from the setpoint value. A precise post-injection is therefore not possible. Disclosure of the invention

The inventive method for operating an injection system for an internal combustion engine according to the independent claims has the advantage over the prior art that a precise post-injection of further terem fuel is made possible in the combustion chamber. This is achieved by using two separate injection valves for injecting the fuel in the first method step, so that each individual injection valve must be designed for a smaller flow of fuel than if only a single injection valve had to inject the entire fuel quantity in the first method step. This advantageously reduces the smallest amount that can still be injected by the injection valves with high accuracy. Further, at a lower flow rate, the turn-on times for each of the intake valves increase to inject the same amount of fuel, so that in the second process step, a longer turn-on pulse is required to re-inject the additional fuel. In this way, the precision of the

Nachspitzvorgangs significantly increased and the risk that the first Einspritzven- til in the non-linear area works cleared away. The inventive method thus allows a very accurate injection of the required amount of fuel even in dynamic operating conditions, which are caused by large load changes. As a result, the engine power is increased during load changes, for example, from idle to full load or from a small load to a large load. The setting of a nearly optimal air-fuel mixture also favors the mixing and burning through, whereby an improved smoothness and a reduced C0 ₂ emissions are achieved during load changes. The internal combustion engine according to the invention preferably comprises a gasoline engine with intake manifold injection for a motor vehicle, preferably an automobile. The internal combustion engine preferably comprises more than one cylinder, wherein each of the cylinders comprises a combustion chamber with two spark plugs and two intake valves, wherein each intake valve is assigned a separate injection valve in each case.

Advantageous embodiments and modifications of the invention are the dependent claims, as well as the description with reference to the drawings. According to a preferred embodiment of the present invention, it is provided that in the second method step, further fuel is injected into the combustion chamber exclusively from the first injection valve through the still open first inlet valve. The first and the second injection valve are thus preferably controlled separately. The post-injection is then carried out exclusively by the first injection valve, so that the smallest possible

Amount of fuel is injectable. Alternatively, it is provided that, in the second method step, further fuel is also injected from the second injection valve into the combustion chamber through the still open second inlet valve. In this case, the first and second injection valves can be controlled jointly. It is conceivable that, depending on the fuel requirement, a variable connection is made between the two re-injection variants so that the available fuel-cell mass range increases considerably in comparison with the prior art.

According to a preferred embodiment of the present invention, it is provided that in the first method step, the first and the second Essentially, the same amount of fuel is injected. In an advantageous manner, the first and second injection valves are thus of identical construction. The use of these two injectors then causes compared to the prior art, a halving of the possible small dispensing amount. In the "normal" injection phase is due to the same dimensions of the

Injectors advantageously achieved a uniform distribution of the fuel-air mixture in the combustion chamber.

According to a preferred embodiment of the present invention, it is provided that, in the first method step, a smaller amount of fuel is injected from the first injection valve than from the second injection valve. In this alternative embodiment, the first and second injection valves are dimensioned differently. This has the advantage of being even lower

Smallest delivery amount of the first injection valve is achieved. For injection, only the first injection valve is then activated, so that advantageously the smallest amounts of further fuel can be accurately injected. The fuel metering range thereby increases considerably as compared to the prior art. Preferably, in the first method step, the first injection valve injects an amount of fuel which is less than 60 percent, preferably less than 30 percent, more preferably less than 20 percent and most preferably less than 10 percent of the amount of fuel delivered by the second injection valve is injected in the first step. The minimum dispensing amount can thus be reduced to less than 30 percent, preferably less than 15 percent, more preferably less than 10 percent and most preferably less than 5 percent, compared to the prior art.

According to a preferred embodiment of the present invention, it is provided that the fuel is injected from the first injection valve immediately adjacent to the first inlet opening. This has the advantage that the time of flight for the further injected fuel is comparatively low, so that a subsequent injection can be initiated at a very late point in time. According to a preferred embodiment of the present invention, it is provided that in the second method step, the first injection valve is dependent on gation of a Nachspritzsignals for re-injection of the other fuel is controlled. The re-injection signal is generated when, for example, corresponding measurement data detects a lean air-fuel mixture and / or the software of an engine control unit predicts a leaner air-fuel mixture.

According to a preferred embodiment of the present invention, it is provided that the post-spray signal in response to a speed of the internal combustion engine, a throttle setting of the internal combustion engine and / or the signals of a arranged in an exhaust passage of the internal combustion engine lambda sensor, arranged in an intake manifold of the internal combustion engine air mass sensor in the intake manifold arranged pressure sensor and / or a temperature sensor is generated. Advantageously, a determination of a lean air-fuel mixture is possible based on the above data.

Embodiments of the present invention are illustrated in the drawings and explained in more detail in the following description.

Brief description of the drawings

Show it

Figure 1 is a schematic representation of an injection system for an internal combustion engine, which performs a first method step of a method according to an exemplary embodiment of the present invention, and Figure 2 is a schematic representation of an injection system for an internal combustion engine, which is a second method step of a method according to an exemplary embodiment of the present invention performs.

Embodiments of the invention

In the various figures, the same parts are always provided with the same reference numerals and are therefore usually named or mentioned only once in each case. 1 shows a schematic representation of an injection system for an internal combustion engine 1, which performs a first method step of a method according to an exemplary embodiment of the present invention, which comprises a cylinder which comprises a combustion chamber 2 and in which a piston 2 'moves , The wall of the combustion chamber 2 has a first and a second inlet opening 10 ', 20', through which in each case an air-fuel mixture is sucked into the combustion chamber 2 and a first and second outlet opening 30, 31, through which the raw gases of the burned Air-fuel mixture from the combustion chamber 2 in first and second outlet channels 32, 33 are ejected. The internal combustion engine 1 has a first inlet valve 10, which is provided for closing the first inlet opening 10 'and is arranged between a first inlet channel 11 and the combustion chamber 2. The internal combustion engine 1 also has a second inlet valve 20, which is provided for closing the second inlet opening 20 'and is arranged between a second inlet channel 21 and the combustion chamber 2. The first and the second intake duct 1 1, 21 open on a side facing away from the combustion chamber 2 in a common intake manifold, not shown, with fresh air sucked through the intake manifold in the direction of the combustion chamber 2 by a throttle valve (not shown) in the intake manifold. In the first intake passage 1 1, a first injection valve 12 is arranged, which has a first injection port 14 through which a fuel mixture 3 is sprayed through the first intake passage 1 1 in the region of the first inlet port 10 '. Similarly, a separate second injection valve 22 is arranged in the second intake passage 21, which has a single second injection opening 24, through which a fuel mixture 3 is sprayed through the second intake passage 21 into the region of the second intake opening 20 '.

In normal driving operation, a predetermined amount of fuel 3 is injected and atomized into the first and second intake manifolds 11, 12 in each cycle by the first and the second injection valves 12, 22, respectively. This takes place in the context of the first method step, which is shown in FIG. The respective resulting air-fuel mixture passes through the first and second inlet valve 10, 20 into the combustion chamber 2. The amount of fuel 3 to be injected is calculated by means of a prediction method. In dynamic driving mode, the calculated injection quantity does not exactly match the actual air charge, since the calculated time between calculation of the air charge and the actual fuel consumption Injection including flight time a change in the filling, for example, by a sudden load change, may occur. Such a load change can occur if, for example, the driver of the motor vehicle requests an increased torque and the throttle valve thereby suddenly opens. It then flows more air into the combustion chamber 2, as was used in the calculation of the required amount of fuel used. For the calculated and injected amount of fuel thus gets too much air in the cylinder, whereby the air-fuel mixture is emaciated. To remedy this problem, further fuel 3 'is injected into the combustion chamber 2 through the first inlet valve 10, which is still open, in a second method step illustrated with reference to FIG.

FIG. 2 shows a schematic representation of the injection system for an internal combustion engine 1 already illustrated in FIG. 1, the second method step of the method according to the exemplary embodiment of the present invention being schematically illustrated in FIG. In the second method step, a small amount of further fuel 3 'is injected by the first injection valve 12 at a later point in time in order to enrich the leaned air-fuel mixture in the combustion chamber 2 with fuel to a desired optimum ratio. The second injection valve 22 is not in operation at this time. In the case of a post-splash, there is basically the problem that the injector has difficulty with the dosage for the smallest amounts. The size of the flow rate Q _sta t of an injector at the same time also the smallest possible discharge amount, also referred to as the smallest amount Q _min defined. The smallest quantity Q _min is an amount that an injector can just inject with a certain accuracy. In the present internal combustion engine 1, two equal-sized separate injection valves, the first and second injection valve 12, 22, used, so that the flow of both injectors 12, 22 is halved and thus also the smallest amount Q _min for each of the two injectors 12, 22nd halved. The first injection valve 12 is thus used for the precise re-injection of a particularly small amount of further fuel 3 '(indicated only schematically in FIG. 2 by a smaller spray cone). Alternatively, it is conceivable that the first and second injection valves 12, 22 are dimensioned differently, so that the first injection valve 12, for example, has flow Q _sta ti, which is smaller than that

Flow Q _sta t2 of the second injection valve 22 is. In this way, the Nachspritzer finer and tuned to the respective combustion be measured.

Claims

claims

1. A method for operating an injection system for a combustion chamber (2) having an internal combustion engine (1), wherein in a first method step, a first inlet valve (10) to the combustion chamber (2) is opened and from a first injection valve (11) fuel (3) In the first method step, a second inlet valve (20) to the combustion chamber (2) is further opened and from a second injection valve (21) fuel (3) through the open second inlet valve (20) is injected into the combustion chamber (2), characterized in that in a second method step at least from the first injection valve (11) further fuel (3 ') through the still open first inlet valve (10) into the combustion chamber (2 ) is sprayed.

2. The method according to claim 1, characterized in that in the second method step exclusively from the first injection valve (11) further fuel (3) is injected by the still open first inlet valve (10) into the combustion chamber (2).

3. The method according to claim 1, characterized in that in the second step of the second injection valve (11) further fuel (3) is injected by the still open second inlet valve (10) into the combustion chamber (2).

4. The method according to any one of the preceding claims, characterized in that in the first process step of the first and the second injection valve (1 1, 21) substantially the same amount of fuel (3) is injected. Method according to one of claims 1 to 3, characterized in that in the first method step from the first injection valve (11) a smaller amount of fuel (3) than from the second injection valve (21) is injected.

A method according to claim 5, characterized in that in the first method step from the first injection valve (1 1) an amount of fuel (3) is injected, which less than 60 percent, preferably less than 30 percent, more preferably less than 20 percent and most especially Preferably, less than 10 percent of the amount of fuel (3), which is injected from the second injection valve (21) in the first step.

Method according to one of the preceding claims, characterized in that from the first injection valve (11) of the fuel (3) immediately adjacent to the first inlet port (10 ') is injected.

Method according to one of the preceding claims, characterized in that in the second method step, the first injection valve (11) is controlled in response to a Nachspritzsignals for re-injection of the further fuel (3), wherein the Nachspritzsignal is generated when an excessive proportion of air in the air fuel Mixture is calculated and / or detected.

A method according to claim 8, characterized in that the post-spray signal in dependence of a rotational speed of the internal combustion engine (1), a throttle valve setting of the internal combustion engine (1) and / or the signals of a in an exhaust passage of the internal combustion engine (1) arranged lambda sensor, one in one Suction pipe of the internal combustion engine (1) arranged air mass sensor, a pressure sensor arranged in the suction pipe and / or a temperature sensor is generated.

0 computer program, characterized in that it is programmed for use in a method according to one of the preceding claims.

1. Storage medium for a control device of an injection system, characterized in that on the storage medium, a computer program for Application in a method according to one of claims 1 to 9 is stored.