WO2017174254A1

WO2017174254A1 - Internal combustion engine having integrated water extraction

Info

Publication number: WO2017174254A1
Application number: PCT/EP2017/053988
Authority: WO
Inventors: Julian HAGENLOCH; Gautam ETHIRAJ; Martin Frohnmaier; Ingmar Burak; Peter Schenk
Original assignee: Robert Bosch Gmbh
Priority date: 2016-04-06
Filing date: 2017-02-22
Publication date: 2017-10-12
Also published as: DE102016205666A1

Abstract

The invention relates to an internal combustion engine, comprising an intake duct (4), an exhaust gas duct (5), an exhaust gas return line (20) that leads from the exhaust gas duct (5) to the intake duct (4) in order to supply exhaust gas to the intake duct (4), a heat exchanger (21) arranged in the exhaust gas return line (20) in order to cool returned exhaust gas, and a water injection assembly (10) having at least one water injector (11), a water tank (14) and a water supply line (15) that connects the water tank with the heat exchanger (21), wherein the heat exchanger (21) is configured to cool the exhaust gas returned to the intake duct (4) in such a way that water vapour present in the exhaust gas is condensed and can be supplied to the water tank (14) by means of the water supply line (15).

Description

Description title

Internal combustion engine with integrated water extraction. 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.

To reduce a tendency to knock and to reduce high levels

Exhaust gas temperatures have recently been made proposals at

Internal combustion engines perform a water injection. 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, especially due to its chemical composition, and may be too

cause 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. To cool the recirculated exhaust gas is in the

Exhaust return disposed a heat exchanger, which transfers heat from the exhaust gas to a cooling medium. Furthermore, the

Internal combustion engine, a water injection assembly 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. Of the

Heat exchanger in the exhaust gas return line is set up, the

Cooling the intake manifold recirculated exhaust gas so that water vapor contained in the exhaust gas can be condensed on the heat exchanger and fed by means of the water supply to the water tank. 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

Flow direction of the exhaust gas in front of the turbine. This will be a

High pressure exhaust gas recirculation possible. The exhaust gas recirculation opens Intake tract preferred 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 returned.

More preferably, a water treatment device is arranged in the water supply from the heat exchanger to the water tank. This can, for example, an activated carbon filter preferably in conjunction with a

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. This is a simple and inexpensive ventilation of the

Water tanks 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 to

Water tank is supplied, preferably a purification of the water is performed.

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

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

Figure 3 is 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

Hereinafter, an internal combustion engine 1 according to a preferred embodiment of the invention will be described in detail with reference to FIG.

As can be seen from FIG. 1, the internal combustion engine 1 comprises a

Engine block 2 with four cylinders 3. Air is fed via an intake and an intake air cooler 40 to the cylinders 3. Reference numeral 9 denotes a throttle valve.

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

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

The internal combustion engine 1 further comprises an exhaust gas recirculation. Here, an exhaust gas return line 20 goes from the exhaust tract 5 back to the intake tract 4. As shown in Figure 1, the exhaust gas return line 20 branches off in the flow direction of the exhaust gas to the turbine 6 and in particular after the catalyst 8. This has the advantage that certain components from the exhaust gas, in particular pollutants, can be converted into less hazardous components by the catalyst 8. The exhaust gas return line 20 opens in the intake tract 4 in the flow direction in front of the compressor 7.

As further seen in Figure 1, is in the exhaust gas return line 20 a

Heat exchanger 21 is arranged. The heat exchanger 21 serves to cool the recirculated exhaust gas. Reference numeral 22 denotes a return line shut-off valve 22.

According to the invention now in the heat exchanger 21, the temperature of the recirculated exhaust gas to a temperature below a

Condensation point of water cooled. As a result, water condenses in the heat exchanger 21. This water is fed via a water supply line 15 to a water tank 14. The heat exchanger 21 is thus as

Condensing device formed.

The internal combustion engine 1 includes a water injection assembly 10, which in addition to the water tank 14 and the water supply 15 also

Water injectors 1 1 includes. The water injectors 1 1 inject water directly into the combustion chambers in the cylinders 3 a. The water is pumped from the water tank 14 by means of a pump 13 to a rail 12, to which all water injectors 1 1 are connected. In this case, the water can be passed through a filter 18 to damage the

To avoid water injectors by particles or the like. A pressure in the water line in the flow direction after the pump 13 is detected by means of a pressure sensor 17.

In the water supply line 15 is still a check valve 16 is arranged to, if the water tank 14 is completely filled with water to close the water supply line 15 so that no more water is supplied into the water tank 14. Furthermore, in the water supply 15, a water treatment device 23 is further arranged to eliminate harmful components, which could damage the water injection assembly 10.

It should be noted that the treatment device 23 in the water supply 15, e.g. Activated carbon comprises to treat the recovered from the recirculated exhaust condensate.

Thus, according to the invention from a recirculated exhaust gas, which is recycled in the exhaust system 5 to an intake manifold 4, water for the

Water injection assembly 10 are obtained. As a result, water can be continuously recovered from the recirculated exhaust gas for the water injection arrangement during operation of the internal combustion engine 1, so that a manual refilling of water into the water tank 14 is not necessary.

Since in the embodiment shown in Figure 1, the exhaust gas recirculation follows in the direction of flow of the intake before the compressor 7, this is a low-pressure exhaust gas recirculation. The arrangement of the shut-off valve 16 in the water supply line 15, it is possible that in suitable operating points, in particular at a relatively low

Exhaust gas pressure, the recovered condensate water can be passed or flushed by means of an overpressure from the exhaust gas return line 20 into the water tank 14.

If necessary, the water in the water treatment device 23 is e.g. by filtration, distillation, supply of chemical treatment substances or any combination of such processes.

Figure 2 shows an internal combustion engine 1 according to a second

Embodiment of the invention. Unlike the first

Embodiment, in the second embodiment, the exhaust gas return line 20 is arranged such that the exhaust gas return line 20 in the exhaust tract 5 in

Flow direction of the exhaust gas is branched off in front of the turbine 6. The recirculated exhaust gas is fed back into the intake tract 4 after the compressor 7. In particular, as can be seen from FIG. 2, in this exemplary embodiment the recirculated exhaust gas is fed in the direction of flow of the intake air into the intake tract 4 downstream of the throttle valve 9. Consequently This is a high-pressure exhaust gas recirculation in this embodiment. Otherwise, this embodiment corresponds to the first embodiment, so that reference may be made to the description given there.

FIG. 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, that is, the

Exhaust return line 20 branches in the exhaust tract 5 to the turbine 6 and

in particular after the catalyst 8 and is fed into the intake tract 4 in front of the compressor 7. It is in the third embodiment in the

Water supply 15 no shut-off valve arranged. Instead, a ventilation duct 19 is provided between the water tank 14 and the intake tract 4. By this tank ventilation pressure equalization is made possible to avoid that exhaust gas is sucked into the water tank 14. A

Water drainage via the water supply line 15 takes place from

Heat exchanger 21 by gravity into the water tank 14th

As set forth in all exemplary embodiments, a targeted cooling of the exhaust gas below the dew point of water can thus be made possible by using a heat exchanger 21 in the exhaust gas return line 20, so that a water condensate can be obtained from the recirculated exhaust gas, which can be used for the water injection arrangement 10. In this case, the exhaust gas is preferably branched off from the exhaust gas tract 5 downstream of the catalytic converter 8, so that as few harmful components as possible are contained in the exhaust gas, in particular in order to avoid excessive corrosion of the components.

Claims

claims

1 . 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) for introducing exhaust gas into the intake tract (4), a heat exchanger (21) disposed in the exhaust gas return line (20) for cooling recirculated exhaust gas, a water injection assembly (10) comprising at least one water injector (1 1), a water tank (14) and a

Water supply (15), which the water tank with the

Heat exchanger (21) connects,

wherein the heat exchanger (21) is arranged to cool the exhaust gas recirculated to the intake tract (4) in such a way that water vapor present in the exhaust gas condenses and can be supplied to the water tank (14) by means of the water supply line (15).

2. Internal combustion engine according to claim 1, further comprising a

Exhaust gas turbocharger with a turbine (6) and a compressor (7), wherein the turbine (6) in the exhaust tract (5) is arranged and the compressor (7) in the intake tract (4) is arranged.

3. Internal combustion engine according to claim 2, characterized in that the exhaust gas return line (20) branches off in the exhaust gas tract (5) in the flow direction of the exhaust gas before the turbine (6) and in the intake tract (4) after a

Throttle valve (9) opens.

4. 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 (8), branches off and into the intake tract (4) before the compressor (4). 7) opens. Internal combustion engine according to one of the preceding claims, characterized in that in the water supply line (15) has a

Processing device (23) is arranged for the water.

Internal combustion engine according to claim 4 or 5, further comprising a ventilation duct (19) which connects the water tank (14) with the intake duct (4).

A method for obtaining 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) in an intake (20) is supplied and by means of a heat exchanger (21) to a temperature below a dew point is cooled by water to recover water condensate from the recirculated exhaust gas and a water injection assembly (10) supply.

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 (8) is removed.

A method according to claim 7, characterized in that the exhaust gas from the exhaust gas tract (5) is removed in the flow direction of the exhaust gas upstream of a turbine of an exhaust gas turbocharger.

A method according to claim 7 or 8 or 9, characterized in that the recirculated exhaust gas is fed into the intake tract (4) of the internal combustion engine before or after a compressor.