DE102016205666A1 - Internal combustion engine with integrated water extraction - Google Patents

Abstract

The invention relates to an internal combustion engine, comprising an intake tract (4), an exhaust tract (5), an exhaust gas return line (20) leading from the exhaust tract (5) to the intake tract (4) to supply exhaust gas into the intake tract (4), a heat exchanger (21) disposed in the exhaust gas recirculation line (20) for cooling recirculated exhaust gas, a water injection device (10) comprising at least one water injector (11), a water tank (14) and a water supply line (15) connecting the water tank with the water tank Heat exchanger (21) connects, wherein the heat exchanger (21) is arranged to cool the recirculated to the intake (4) exhaust gas so condensed in the exhaust water vapor and by means of the water supply (15) to the water tank (14) can be fed.

Description

State of the art

The present invention relates to an internal combustion engine with an integrated water extraction for a water injection system of the internal combustion engine and a method for recovering water from exhaust gas.

In order to reduce a tendency to knock and to reduce high exhaust gas temperatures proposals have recently been made to perform a water injection in internal combustion engines. The water can either be injected directly into a combustion chamber of the internal combustion engine or into an intake tract of the internal combustion engine. In order to install such water injection systems in series in vehicles, it must be ensured that there is sufficient water in the water tank. In this case, it would be desirable if a user of the vehicle is not forced to automatically fill water, for example via a refill pipe, into the water tank. Furthermore, it is known to carry out an exhaust gas recirculation in internal combustion engines. In this case, a portion of the exhaust gas is returned back into the intake and mixed with the fresh air. This increases a proportion of inert gas in the fuel gas, which in particular throttle losses can be reduced in partial load ranges of the internal combustion engine. It is known that a cooling of the exhaust gas is carried out in the exhaust gas return line. However, care has been taken here that the cooling is not such that condensate can form and accumulate in the exhaust gas recirculation system. Such a condensate is highly corrosive, in particular due to its chemical composition and can lead to corresponding damage to the exhaust gas recirculation system.

Disclosure of the invention

The internal combustion engine according to the invention with the features of claim 1 comprises an intake and an exhaust tract and an exhaust gas return. The exhaust gas recirculation leads from the exhaust tract to the intake tract to recirculate exhaust gas into the intake tract. In order to cool the recirculated exhaust gas, a heat exchanger is arranged in the exhaust gas return line, which transfers heat from the exhaust gas to a cooling medium. Furthermore, the internal combustion engine comprises a water injection arrangement with at least one water injector, a water tank and a water supply line. The water supply connects the heat exchanger with the water tank. The heat exchanger in the exhaust gas return line is set up to cool the exhaust gas recirculated to the intake tract in such a way that water vapor contained in the exhaust gas condenses on the heat exchanger and can be guided to the water tank by means of the water supply line. Thus, in contrast to the prior art, the heat exchanger in the exhaust gas return line is set up such that water can condense here and can be used for the water injection arrangement. As a result, sufficient water can be recovered from the recirculated exhaust gas during operation of the internal combustion engine, so that manual refilling by a user of the internal combustion engine is not necessary. In this case, the inventive idea can be implemented very easily and inexpensively, if the internal combustion engine is designed anyway for exhaust gas recirculation. In this case, only a cooling of the recirculated exhaust gas must be provided, such that the temperature at the heat exchanger is selected such that water can condense in the recirculated exhaust gas and can be removed. Thus, the heat exchanger in the exhaust gas return line is a condensation device for recovering water.

The dependent claims show preferred developments of the invention. More preferably, the internal combustion engine comprises an exhaust gas turbocharger with a turbine and a compressor, wherein the turbine is arranged in the exhaust tract, in particular in order to drive the compressor.

Particularly preferably, the exhaust gas return line branches off in the exhaust gas tract in the flow direction of the exhaust gas in front of the turbine. As a result, a high-pressure exhaust gas recirculation is possible. The exhaust gas recirculation flows in the intake tract preferably in the direction of flow of the intake tract to a throttle valve.

Alternatively, the exhaust gas return line branches off in the direction of flow of the exhaust gas in the exhaust gas tract downstream of the turbine, in particular downstream of a catalytic converter. As a result, a low-pressure exhaust gas return line is realized. The diversion after the catalyst also has the advantage that purified exhaust gas can be recycled.

More preferably, a water treatment device is arranged in the water supply from the heat exchanger to the water tank. This can be, for example, an activated carbon filter preferably in conjunction with an ion exchanger to avoid harmful pH values in the condensate. As a result, especially harmful components in the recovered water can be filtered out.

According to a further preferred embodiment of the present invention, a ventilation line is provided, which connects the water tank with the intake. As a result, a simple and inexpensive ventilation of the water tank is possible.

Furthermore, the present invention relates to a method for obtaining water from an exhaust gas of an internal combustion engine, wherein the exhaust gas is passed from an exhaust tract via an exhaust gas return line in an intake. By means of a heat exchanger, the recirculated exhaust gas in the exhaust gas return line is cooled to a temperature below a condensation temperature of water, so that water is condensed from the exhaust gas and then fed to a water tank. Before the water is supplied to the water tank, cleaning of the water is preferably carried out.

drawing

Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. The same or functionally identical parts are denoted by the same reference numerals. In the drawing is:

1 a schematic representation of an internal combustion engine with a water extraction device according to a first embodiment of the invention,

2 a schematic representation of an internal combustion engine with a water extraction device according to a second embodiment of the invention, and

3 a schematic representation of an internal combustion engine with a water extraction device according to a third embodiment of the invention.

Embodiments of the invention

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

How out 1 can be seen, includes the internal combustion engine 1 an engine block 2 with four cylinders 3 , Air is supplied via an intake manifold and an intake air cooler 40 to the cylinders 3 guided. The reference number 9 denotes a throttle valve.

In the intake tract 4 is still a compressor 7 intended. The compressor 7 is in the flow direction of the intake tract 4 in front of the intake air cooler 40 arranged.

Exhaust gas is from the cylinders 3 in an exhaust tract 5 guided. In the exhaust tract 5 is a turbine 6 and a catalyst 8th arranged. The arrows in the intake tract 4 or in the exhaust tract 5 denote the flow direction of the respective gases.

The internal combustion engine 1 further includes exhaust gas recirculation. This is an exhaust gas return line 20 from the exhaust tract 5 back to the intake tract 4 , As in 1 shown, branches the exhaust gas return line 20 doing so in the flow direction of the exhaust gas to the turbine 6 and especially after the catalyst 8th from.

This has the advantage that through the catalyst 8th Certain components of the exhaust gas, especially pollutants, can be converted into less hazardous components.

The exhaust gas return line 20 discharges in the intake tract 4 in the flow direction in front of the compressor 7 ,

How farther 1 it is apparent in the exhaust gas return line 20 a heat exchanger 21 arranged. The heat exchanger 21 serves to cool the recirculated exhaust gas. The reference number 22 denotes a return line shut-off valve 22 ,

According to the invention is now in the heat exchanger 21 cooled the temperature of the recirculated exhaust gas to a temperature below a condensation point of water. As a result, water condenses in the heat exchanger 21 , This water is supplied via a water supply 15 to a water tank 14 guided. The heat exchanger 21 is thus formed as a condensation device.

The internal combustion engine 1 includes a water injection assembly 10 , which is next to the water tank 14 and the water supply 15 also water injectors 11 includes. The water injectors 11 Water splashes directly into the combustion chambers in the cylinders 3 one. The water gets out of the water tank 14 by means of a pump 13 to a rail 12 on which all water injectors 11 connected, pumped. Here, the water can pass through a filter 18 be passed to avoid damage to the water injectors by particles or the like. A pressure in the water pipe in the direction of flow after the pump 13 is by means of a pressure sensor 17 detected.

In the water supply 15 is still a shut-off valve 16 arranged to, if the water tank 14 completely filled with water, the water supply 15 to close, so that no more water in the water tank 14 is supplied.

Furthermore, in the water supply 15 Further, a water treatment device 23 arranged to harmful components containing the water injection assembly 10 could damage, eliminate.

It should be noted that the processing device 23 in the water supply 15 For example, activated carbon comprises to treat the recovered from the recirculated exhaust condensate.

Thus, according to the invention from a recirculated exhaust gas, which in the exhaust system 5 to an intake tract 4 is recycled, water for the water injection assembly 10 be won. This can be continuously during operation of the internal combustion engine 1 Water is recovered from the recirculated exhaust gas for the water injection assembly, allowing a manual refilling of water into the water tank 14 is not necessary.

Since at the in 1 shown embodiment, the exhaust gas recirculation in the direction of flow of the intake system in front of the compressor 7 follows, this is a low-pressure exhaust gas recirculation. By the arrangement of the shut-off valve 16 in the water supply 15 it is possible that in suitable operating points, in particular at a relatively low exhaust pressure, the condensate water obtained with the aid of an excess pressure from the exhaust gas return line 20 in the water tank 14 can be directed or rinsed.

If necessary, the water in the water treatment device 23 For example, by filtering, distillation, supply of chemical treatment substances or any combination of such methods, processed.

2 shows an internal combustion engine 1 according to a second embodiment of the invention. In contrast to the first embodiment, the exhaust gas return line is in the second embodiment 20 arranged such that the exhaust gas return 20 in the exhaust tract 5 in the flow direction of the exhaust gas in front of the turbine 6 is branched off. The recirculated exhaust gas is thereby in the intake 4 after the compressor 7 fed again. In particular, as is out 2 it can be seen, in this embodiment, the recirculated exhaust gas in the flow direction of the intake air in the intake 4 after the throttle 9 fed. Thus, this embodiment is a high-pressure exhaust gas recirculation. Otherwise, this embodiment corresponds to the first embodiment, so that reference may be made to the description given there.

3 shows an internal combustion engine 1 according to a third embodiment of the invention. The exhaust gas return line 20 is arranged according to the first embodiment, ie, the exhaust gas return line 20 branches in the exhaust tract 5 after the turbine 6 and especially after the catalyst 8th off and gets into the intake tract 4 in front of the compressor 7 fed. It is in the third embodiment in the water supply 15 no shut-off valve arranged. Instead, between the water tank 14 and the intake tract 4 a ventilation duct 19 intended. Through this tank ventilation, a pressure equalization is made possible to avoid exhaust gas in the water tank 14 is sucked. A water drainage via the water supply 15 takes place from the heat exchanger 21 by gravity into the water tank 14 ,

As stated in all embodiments, can thus by using a heat exchanger 21 in the exhaust gas return line 20 a targeted cooling of the exhaust gas below the dew point of water are made possible, so that from the recirculated exhaust gas, a water condensate can be obtained, which for the water injection assembly 10 is usable. The exhaust gas is preferably from the exhaust gas tract 5 after the catalyst 8th diverted, so that as few harmful components are contained in the exhaust gas, in particular to avoid excessive corrosion of the components.

Claims (10)

Internal combustion engine, comprising: - an intake tract ( 4 ), - an exhaust tract ( 5 ), - an exhaust gas return line ( 20 ), which from the exhaust tract ( 5 ) to the intake tract ( 4 ) leads to exhaust gas in the intake tract ( 4 ), - a heat exchanger ( 21 ), which in the exhaust gas return line ( 20 ) is arranged to cool recirculated exhaust gas, - a water injection assembly ( 10 ) comprising at least one water injector ( 11 ), a water tank ( 14 ) and a water supply ( 15 ), which the water tank with the heat exchanger ( 21 ), - wherein the heat exchanger ( 21 ), which is connected to the intake tract ( 4 ) cooled exhaust gas so condensed that present in the exhaust water vapor and by means of the water supply ( 15 ) to the water tank ( 14 ) can be fed. Internal combustion engine according to claim 1, further comprising an exhaust gas turbocharger with a turbine ( 6 ) and a compressor ( 7 ), whereby the turbine ( 6 ) in the exhaust tract ( 5 ) is arranged and the compressor ( 7 ) in the intake tract ( 4 ) is arranged. Internal combustion engine according to claim 2, characterized in that the exhaust gas return line ( 20 ) in the exhaust tract ( 5 ) in the flow direction of the exhaust gas before the turbine ( 6 ) branches off and in the intake tract ( 4 ) after a throttle valve ( 9 ) opens. Internal combustion engine according to claim 2, characterized in that the exhaust gas return line ( 20 ) in the exhaust tract ( 5 ) in the flow direction of the exhaust gas after the turbine, and in particular after a catalyst ( 8th ), branches off and into the intake tract ( 4 ) in front of the compressor ( 7 ) opens. Internal combustion engine according to one of the preceding claims, characterized in that in the water supply line ( 15 ) a processing device ( 23 ) is arranged for the water. Internal combustion engine according to claim 4 or 5, further comprising a ventilation line ( 19 ), which the water tank ( 14 ) with the intake tract ( 4 ) connects. A method for recovering water from a recirculated exhaust gas of an internal combustion engine, wherein the exhaust gas from an exhaust tract ( 5 ) of the internal combustion engine via an exhaust gas return line ( 20 ) into an intake tract ( 20 ) and by means of a heat exchanger ( 21 ) is cooled to a temperature below a dew point of water to recover water condensate from the recirculated exhaust gas and a water injection assembly ( 10 ). A method according to claim 7, characterized in that the exhaust gas from the exhaust gas tract ( 5 ) in the flow direction of the exhaust gas after a catalyst ( 8th ) is taken. A method according to claim 7, characterized in that the exhaust gas from the exhaust gas tract ( 5 ) is taken in the flow direction of the exhaust gas before a turbine of an exhaust gas turbocharger. A method according to claim 7 or 8 or 9, characterized in that the recirculated exhaust gas in the intake tract ( 4 ) is supplied to the internal combustion engine before or after a compressor.

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