DE102018209135A1 - Internal combustion engine with water injection and method for operating an internal combustion engine - Google Patents

Abstract

The present invention relates to an internal combustion engine having a water injection system (2) and a fuel injection system (3), comprising a fuel injector (32), which is arranged directly on a combustion chamber (10), and a water injector (22), which at a suction region (8 ) of the internal combustion engine is arranged to inject water into the suction region (8), wherein the fuel injector is arranged to inject only fuel directly into the combustion chamber or to be connected to the water injection system (2) to a fuel-water mixture in the combustion chamber inject. Furthermore, the invention relates to a method for operating an internal combustion engine.

Description

State of the art

The present invention relates to an internal combustion engine with a water injection system and a method for operating an internal combustion engine with water injection.

Internal combustion engines with water injection systems are known from the prior art in various configurations. By injecting water, it is possible here to achieve a reduction in a tendency to knock and a reduction in exhaust gas temperatures. Usually known are separate water injection systems, which allow water injection. Here is, for example, from the DE 102015208476 A1 an internal combustion engine with a water injection system, in which a water injector injects water in the direction of an inlet valve of the internal combustion engine in a suction region. The water injector is in this case arranged in particular on an inlet channel for supplying combustion air into a combustion chamber. In order to achieve an increase in an amount of water injectable per combustion cycle, it is further preferred to provide two water injectors per cylinder. This system has proven itself in principle, but it would be desirable to have other alternative water injection systems.

Disclosure of the invention

The internal combustion engine according to the invention with the features of claim 1 has the advantage that, in comparison with known water injection systems in particular a saving of injected water is possible. This is inventively achieved in that the internal combustion engine comprises a water injection system and a fuel injection system, wherein a fuel injector is arranged directly on a combustion chamber. As a result, a direct injection can be realized. The water injection system further includes a separate water injector disposed at a suction region of the internal combustion engine to inject water into the suction region. The fuel injector is now configured to either inject only fuel directly into the combustion chamber or to be connected to the water injection system to also inject mixture of fuel and water directly into the combustion chamber. The mixture is in this case an emulsion of fuel and water, whereby a higher efficiency in the water injection is made possible by the direct injection of water into the combustion chamber, so that a total of water can be saved. Thus, a fuel-water emulsion injection can be combined directly into a combustion chamber with intake manifold water injection.

The dependent claims show preferred developments of the invention.

Preferably, the water injection system has a water pipe connecting a water tank to the water injector. Here, a branched from the water line water connection line is provided, wherein a metering valve is arranged in the water connection line to provide a connection to the fuel injection system or to prevent. As a result, water can be supplied to the fuel injection system when the metering valve is open, and thus a fuel-water emulsion can be injected directly into the combustion chamber via the fuel injector.

Preferably, the fuel injection system comprises a fuel pump to supply fuel to the fuel injector, wherein the water connection line opens at the fuel pump and thus can supply water to the fuel pump. Thus, a good mixing of fuel and water when supplying water to the fuel pump is achieved.

More preferably, the internal combustion engine comprises a control unit which is set up to open and close the metering valve. The control unit preferably opens the metering valve when a knocking of the internal combustion engine is detected or the risk of knocking is detected.

The fuel pump is preferably a high pressure pump to provide a high pressure level for injection via the fuel injector.

More preferably, the control unit is set up to both open the water injector when a water requirement of the internal combustion engine and at the same time to open the metering valve. As a result, a very short response time of the water injection is possible because water can be supplied into the combustion chamber immediately by the water injection into the intake manifold, so that a period of time in which the fed into the fuel circuit water reaches the fuel injector, can be bridged. Due to the hydraulic volume in the fuel injection system from the point at which the water is supplied to the fuel injection system to the fuel injector, this process can take several seconds.

The internal combustion engine is preferably an Otto internal combustion engine.

Furthermore, the present invention relates to a method for operating an internal combustion engine, in particular an Otto internal combustion engine. In the method according to the invention, in this case a fuel-water mixture can be injected by means of a fuel injector directly into a combustion chamber of the internal combustion engine and also water can be injected by means of a water injector in a suction region of the internal combustion engine. The fuel injector is further configured to also inject only fuel directly into the combustion chamber. Thus, a combination of a port injection of water and a direct injection of water in the form of a fuel-water emulsion can be made possible in the combustion chamber, wherein an existing fuel injector is also available for the water injection.

The method according to the invention is preferably configured in such a way that, when water is required, water is first injected into the suction region of the internal combustion engine by means of the water injector. In this way, a time span can be bridged, in which the water is supplied from a water feed point in the fuel injection system to the fuel injector.

With a water requirement of the internal combustion engine, it is also preferable for water to be injected simultaneously through the water injector into the intake region of the internal combustion engine as well as through direct injection of a fuel-water mixture by means of the fuel injector directly into the combustion chamber of the internal combustion engine. In this way, in particular a large amount of water can be supplied into the combustion chamber, wherein for the injection of water in the separate water injector in addition, the fuel injector can be used.

More preferably, injection of water by means of the water injector is terminated when it is determined that an amount of injected water injected through the fuel-water mixture via the fuel injector is sufficient. As a result, a high water consumption can be avoided because a higher efficiency is made possible by the direct water injection into the combustion chamber.

Further preferably, after a shutdown of the internal combustion engine, a water pump is operated by reversing a conveying direction of the water pump in order to lead water from the water line back into a water tank. As a result, in particular damage can be avoided by freezing the water in the water injection system.

list of figures

• 1 eine schematische Ansicht einer Brennkraftmaschine gemäß einem bevorzugten Ausführungsbeispiel der Erfindung, und
• 2 eine schematische Schnittansicht eines Teils der Brennkraftmaschine von 1.

Hereinafter, a preferred embodiment of the invention will be described in detail with reference to the accompanying drawings. In the drawing is:

• 1 a schematic view of an internal combustion engine according to a preferred embodiment of the invention, and
• 2 a schematic sectional view of a part of the internal combustion engine of 1 ,

Preferred embodiment of the invention

The following is with reference to the 1 and 2 an internal combustion engine 1 and a method for operating an internal combustion engine according to a preferred embodiment of the invention described in detail.

The internal combustion engine 1 This embodiment is an Otto internal combustion engine with a water injection system 2 and a fuel injection system 3 , The fuel injection system 3 is a direct injection system, ie fuel is directly into a combustion chamber 10 injected. The fuel injection system 3 includes a fuel tank 30 , a high-pressure fuel pump 31 , a low-pressure fuel pump 35 and a fuel line 33 connecting the fuel tank with a fuel rail 34 combines. How out 1 can be seen, go from the fuel rail 34 short connecting lines 34a to fuel injectors 32 , which is directly at the combustion chamber 10 are arranged. The reference number 33a denotes a pipe section of the fuel pipe 33 that of the high pressure fuel pump 31 to the fuel rail 34 leads.

The water injection system 2 includes a water tank 20 and a water pump 21 , A water pipe 23 connects the water tank 20 with a water trail 24 , From the water trail 24 go connecting pipes to water injectors 21 from.

How out 1 is apparent, are the water injectors 22 while at a suction area 8th arranged the internal combustion engine for sucking combustion air. The position of the water injectors 22 is here immediately adjacent to intake valves 7 at the combustion chambers 10 the internal combustion engine. Thus, low-pressure water injection into a suction region of the internal combustion engine can be enabled.

The high pressure fuel pump 31 is via a camshaft 6 actuates and brings the fuel in the line section 33a to a high fuel pressure level, to direct injection into the combustion chamber 10 to enable.

2 shows again in detail the arrangement of the water injector 22 at the suction area 8th in the flow direction through the suction area after a throttle valve 11 and immediately adjacent to an inlet valve 7 the internal combustion engine. An outlet valve is denoted by the reference numeral 9 characterized.

How farther 1 is apparent, is a water connection line 25 provided the water injection system 2 with the fuel injection system 3 combines. In the water connection line 25 is a metering valve 4 arranged.

How out 1 it can be seen, is the metering valve 4 a 2/2-way valve and has a first position, in which a connection between the water injection system 2 and fuel injection system 3 is interrupted and a second position in which a connection between water injection system 2 and fuel injection system 3 is made. In 1 is the first, interrupted position of the metering valve 4 shown.

The water connection line 25 connects the water pipe 23 with the high pressure fuel pump 31 , This ensures that at an intake stroke of the high-pressure fuel pump 31 and a connecting position of the metering valve 4 Water from the water pipe 23 is sucked and brought to an equal level of pressure, as the fuel to be injected. This is in the line section 33a the fuel line 33 a fuel-water mixture in the form of an emulsion, which is the fuel rail 34 to be led. Here is then a distribution to the fuel injectors 32 so that they inject the fuel-water mixture directly into the combustion chamber.

Thus, in the internal combustion engine 1 Water on the one hand into a suction area 8th be injected on the other hand, in the form of a fuel-water mixture directly into the combustion chamber 10 be injected. Thus, fuel-water direct injection can be combined with intake manifold water injection.

The metering valve 4 is by means of a control unit 5 activated, which in dependence of a water requirement of the internal combustion engine, the metering valve 4 into closed or open position. The control unit 5 also controls the water injectors 22 at what for clarity in 1 not shown.

As in the invention, the injection of water immediately before the intake valves 7 can be done individually per combustion chamber 10 the engine, a corresponding water demand on the water injectors 22 be injected. Thus, in particular, water can be injected precisely via the water injectors for each combustion cycle.

Furthermore, according to the invention via the fuel injector 32 Water also in the form of the fuel-water emulsion directly into the combustion chamber 10 be injected. This has the advantage that the water can be introduced here with a higher efficiency in the combustion chamber, so that a water consumption of the internal combustion engine can be reduced. However, since after opening the metering valve 4 it takes a short period of time, in particular several seconds, until that by means of the high-pressure fuel pump 31 generated fuel-water mixture reaches up to the fuel injectors, during this period water can always through the water injectors 22 also be injected individually for each cylinder. The time until the fuel-water mixture reaches the fuel injectors 32 depends on the hydraulic volume of the fuel rail and the line section 33a between high-pressure fuel pump and fuel rail 34 from.

Once then water along with the fuel through the fuel injector 32 in the combustion chamber 10 can inject a lot of injected water through the water injectors 22 be reduced or be completely adjusted depending on the water demand of the engine.

Thus, the internal combustion engine 1 via the water injection system 2 Immediately inject water into the suction area of the internal combustion engine and at the same time the metering valve 4 open to water via the high pressure fuel pump 31 in the fuel injection system 3 contribute. Once then the fuel water emulsion the fuel injectors 32 achieved, the injected amount of water can through the water injectors 22 be reduced or adjusted. If the water requirement of the internal combustion engine can no longer be covered by the fuel-water emulsion, additional water can be added via the water injectors 22 in the suction area 8th the internal combustion engine are injected.

When the internal combustion engine 1 is turned off, the fuel-water emulsion from the fuel injection system 3 discharged. Furthermore, the water injection system 2 emptied to freeze the water in the injection system at temperatures below the freezing point of water 2 to avoid. Here, the water, for example by means of conveying direction reversal of the water pump 21 back to the water tank 20 be encouraged.

Thus, the internal combustion engine 1 combine a Wassersaugrohreinspritzung with a direct water injection, wherein for the direct water injection next to the metering valve 4 and the water connection line 25 no further components are necessary. As a result, the entire system can be provided and operated very inexpensively. Also, the amount of water needed in operation can be significantly reduced compared to a pure intake manifold water injection.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102015208476 A1 [0002]

Claims (11)

An internal combustion engine having a water injection system (2) and a fuel injection system (3), comprising: - A fuel injector (32) which is arranged directly on a combustion chamber (10), and a water injector (22) which is arranged on a suction region (8) of the internal combustion engine in order to inject water into the suction region (8), - wherein the fuel injector is arranged to inject only fuel directly into the combustion chamber or to be connected to the water injection system (2) to inject a fuel-water mixture into the combustion chamber. Internal combustion engine after Claim 1 wherein the water injection system comprises a water pipe (23) connecting a water tank (20) to the water injector (22) and comprising a water connection pipe (25) branching from the water pipe (23), a metering valve (4) in the water Connecting line (25) is arranged to supply water into the fuel injection system (3). Internal combustion engine according to one of the preceding claims, wherein the fuel injection system (3) comprises a fuel pump (31) which supplies fuel to the fuel injector (32), wherein the water connection line (25) connects the water line (23) with the fuel pump (31). Internal combustion engine after Claim 2 or 3 , further comprising a control unit (5), which is arranged to actuate the metering valve (4). Internal combustion engine according to one of Claims 3 or 4 wherein the fuel pump (31) is a high pressure fuel pump. Internal combustion engine after Claim 4 or 5 , wherein the control unit (5) is arranged to open the water injectors (22) and at the same time the metering valve (4) when the water requirement of the internal combustion engine. Method for operating an internal combustion engine (1), wherein water can be injected by means of a water injector (22) in a suction region (8) of the internal combustion engine and wherein a fuel-water mixture by means of a fuel injector (32) injected directly into a combustion chamber (10) can be. Method according to Claim 7 , In a water requirement of the internal combustion engine water is injected immediately by means of the water injectors (22) in the suction region (8) of the internal combustion engine. Method according to Claim 8 wherein at a water demand of the internal combustion engine water is simultaneously injected by means of the water injector (22) and by means of the fuel injector (32) in the form of a fuel-water mixture. Method according to one of Claims 7 to 9 wherein an injection of water by means of the water injector (22) is terminated when an amount of injected water injected by the fuel injector (32) through the fuel-water mixture is sufficient. Method according to one of Claims 7 to 10 , After switching off the internal combustion engine, a water pump (21) by reversing the conveying direction of the water pump in the water pipe (23) located in a water tank (20) is emptied.

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