DE102015213954A1 - Condensate recovery from an exhaust system of an internal combustion engine - Google Patents

Abstract

The invention relates to a device for condensate extraction from an exhaust system of an internal combustion engine, in particular for water production for a water injection system of an internal combustion engine of a motor vehicle, as well as an exhaust system with such a device and a muffler. The device has a condenser for condensing water vapor present in the exhaust gas of the internal combustion engine into liquid water, an exhaust gas removal device provided in the exhaust gas flow direction in front of a silencer of the exhaust system in an exhaust line of the exhaust system for branching off an exhaust gas partial flow from the exhaust system and for feeding the diverted exhaust gas partial flow into the condenser, and an exhaust gas inlet device provided in the exhaust gas flow direction downstream of the muffler in the exhaust gas line for returning exhaust gas from the branched exhaust gas partial flow into the exhaust gas after its passage through the condenser. In this case, the device for condensate recovery forms an exhaust gas bypass to remove the partial exhaust gas flow from the exhaust line to lead him to condensate bypassing the muffler through the arranged outside the muffler capacitor and return it in the exhaust gas flow direction behind the muffler back into the exhaust system. Thus, an efficient condensate recovery from an exhaust system of an internal combustion engine can be achieved.

Description

The present invention relates to the recovery of condensate from an exhaust system of an internal combustion engine, in particular for the production of water for a water injection system of an internal combustion engine of a motor vehicle. Specifically, the invention relates to a device for condensate extraction from an exhaust system of an internal combustion engine and an exhaust system with a silencer and such a device for condensate recovery.

For internal combustion engines, especially for internal combustion engines of motor vehicles, it is known to increase performance and reduce harmful emissions in the exhaust gas, the fuel-air mixture for operating the engine with water and inject it into the combustion chamber. By injecting water into the intake system or directly into the cylinder, the temperature of the compressed air can be lowered. A charge air cooler usually used for air cooling can only lower the air by a limited temperature delta. The injection of water, however, creates additional evaporation cold, so that the temperature can be further reduced. The then compressed in the cylinder air mixture then has correspondingly also a much lower temperature than without water injection and the compression work can thus be reduced. In particular, in this way the ignition timing can be clearly advanced in a gasoline engine, which can lead to an increase in performance. As an additional effect, a lowering of the exhaust gas temperature occurs. Especially in supercharged high-performance engines, the exhaust gas temperatures are a limiting element, because turbos and catalytic converters may only be loaded up to a certain limit temperature. To protect them without water injection, under full load the fuel-air mixture may be partially enriched with fuel to lower the exhaust gas temperatures so that fuel is used to cool the exhaust gas. Water injection offers an alternative to this, in which turbocharged engines do not need to be greased as described under full load and water is used instead of additional fuel to limit exhaust gas temperatures. Due to the lower temperatures, it is also possible to reduce the pollutant concentration, in particular the nitrogen oxide concentration, in the exhaust gas.

The water required for the water injection must either be carried in the vehicle by means of a corresponding water tank or preferably generated while driving. For this purpose, it is known that to win water from the exhaust gas of the internal combustion engine by means of condensation.

Thus, in the international published patent application WO 01/92710 A1 describes a method and a device for recovering water from an exhaust system, wherein the required amount of water is obtained from the exhaust gas of an internal combustion engine by means of a condensation device which has an average condensation efficiency of at least 25%, preferably at least 50%, over the entire operating range of the internal combustion engine that provision of additional water can be avoided. Here, according to a described embodiment in the exhaust line between a catalyst and a muffler, a condensation device is arranged with a condensate collection through which flows from the exhaust gas coming from catalyst and condensed with the aforementioned condensation efficiency of the water content therein to be supplied to a water injection system for the internal combustion engine.

In the German Offenlegungsschrift DE 10 2012 207 903 A1 is a device for recovering water from an exhaust system of an internal combustion engine, in particular for a water injection insert for the internal combustion engine described. In this case, a cooled by means of cooling water condenser for condensing contained in the exhaust gas of the engine water vapor to liquid water is arranged in the exhaust system. The water is collected in a collecting container of a water injection system of the internal combustion engine, wherein the condenser is arranged in a silencer, in particular in a rear silencer of the exhaust system. Specifically, a muffler is described in which the inflowing exhaust gas stream is divided into a main path leading through a condenser and a bypass passing by it as a secondary path in order to avoid boiling of the cooling water at high exhaust gas flow rates and to protect the exhaust gas condenser.

The invention has for its object to further improve the condensate recovery from an exhaust system of an internal combustion engine, in particular for water production for a water injection system of an internal combustion engine of a motor vehicle, in particular with regard to the efficiency of condensate recovery.

A solution to this problem is achieved according to the teaching of the independent claims by a device according to claim 1 for condensate extraction from an exhaust system of an internal combustion engine and an exhaust system according to claim 15 with a muffler and such a device for condensate recovery.

Various embodiments and development of the invention are the subject of the dependent claims.

A first aspect of the invention relates to a device for condensate extraction from an exhaust system of an internal combustion engine, in particular for water production for a water injection system of an internal combustion engine of a motor vehicle. The device has a condenser for condensing water vapor present in the exhaust gas of the internal combustion engine into liquid water. Furthermore, it has an exhaust gas removal device provided in the exhaust gas flow direction in front of a silencer of the exhaust system in an exhaust line of the exhaust system for branching off a partial exhaust gas stream from the exhaust system and for feeding the branched partial exhaust gas stream into the condenser. In addition, a arranged in the exhaust gas flow direction downstream of the muffler in the exhaust system exhaust inlet device for returning exhaust gas of the branched exhaust gas partial stream is provided in the exhaust gas after its passage through the capacitor. In this case, the device for condensate recovery forms an exhaust gas bypass to remove the partial exhaust gas flow from the exhaust line to lead him to condensate bypassing the muffler through the arranged outside the muffler capacitor and return it in the exhaust gas flow direction behind the muffler back into the exhaust system.

A "condenser" in the sense of the invention means a device in which a substance is converted from the gaseous state of matter into the liquid state of matter. In particular, at least one component of a gas, in particular water vapor in the exhaust gas of an internal combustion engine, can be cooled to such an extent that the component of the gas at least partially changes into the liquid state of matter. The liquefied substance is called "condensate".

Under "water" in the context of the invention, in addition to pure water in particular also to understand that which is part of a condensate of exhaust gas of an internal combustion engine and impurities, in particular exhaust-specific impurities.

Under "exhaust gas flow direction" in the context of the invention, the flow direction of the exhaust gas of an internal combustion engine by an associated exhaust system to understand when it flows from the internal combustion engine coming through the exhaust system to its output port, which may be given in particular by one or more tailpipes.

"Exhaust line" within the meaning of the invention is the part of an exhaust system of an internal combustion engine to understand, by which the exhaust gas of the internal combustion engine is passed from this to the output port of the exhaust system. The exhaust gas system may in particular comprise pipelines, silencers and emission protection devices, such as a catalytic converter or exhaust gas filter.

An "exhaust gas removal device" in the sense of the invention is to be understood as a device for the exhaust gas line which, during operation of the exhaust system, diverts a portion of the exhaust gas from the gas flow by means of the exhaust gas removal device as a partial exhaust gas stream and leads it into the condenser , Accordingly, the exhaust gas removal device acts as a branch for dividing the exhaust gas stream into at least two separate exhaust gas streams at least temporarily, wherein the partial exhaust gas stream, which is conducted to the condenser, serves to recover condensate from the exhaust gas.

An "exhaust gas inlet device" in the sense of the invention is to be understood as a device for the exhaust gas line which leads into an exhaust gas line of an internal combustion engine and serves to recirculate exhaust gas from a partial exhaust gas stream previously branched off from the exhaust gas line into the exhaust gas line.

An "exhaust gas bypass" in the sense of the invention is an exhaust gas path in the exhaust system of an internal combustion engine which branches off from an exhaust system of an internal combustion engine to bypass at least one element of the exhaust system, in particular a silencer, and which is then returned to the exhaust system in that the exhaust gas guided through the exhaust path does not flow through the at least one bypassed element.

Thus, only the portion required for condensate extraction exhaust stream is diverted from the exhaust stream in the exhaust line without this is passed through the muffler, whereby on the one hand the device for condensate extraction can be performed independently of the muffler, and on the other by the arrangement of the capacitor in Exhaust gas flow direction before the muffler, a substantial thermal decoupling of the capacitor can be achieved by the muffler. In this way it is possible to increase the efficiency of the condensate recovery, because neither the entire heat-carrying exhaust gas flow is passed through the condenser, nor the effect of the condenser is reduced by thermal interaction with the exhaust gases heated by the muffler. Another advantage is that the muffler for implementing the Condensate recovery does not have to be modified. On the contrary, even retrofitting or replacement of the device for condensate recovery is possible without the need to change or replace the muffler.

Hereinafter, preferred embodiments of the apparatus for condensate recovery and their developments are described, each of which, as far as it is not mutually exclusive alternatives, can also be combined.

According to a first preferred embodiment, the exhaust gas removal device is configured such that a back pressure arises during operation of the exhaust gas system by the exhaust gas flowing into the exhaust gas line. For this purpose, the exhaust gas extraction device may in particular have an inlet mouth section, which engages in the exhaust gas line feeding the exhaust gas. The inlet opening section preferably has a cross-section which tapers in the direction of the partial exhaust gas branching off into the exhaust gas bypass, preferably in the form of a funnel. In this way, the generation of a negative pressure in the exhaust gas bypass is promoted with an associated suction effect.

Also, in a preferred embodiment of this embodiment, the cross section of the inlet opening section in the further course of the exhaust gas bypass be increased again, so that there is a relaxation of the exhaust gas with a concomitant cooling of the exhaust gas and the inlet mouth section thus acts as a nozzle, which continues the condensation promotes.

According to a further preferred embodiment, the exhaust gas inlet device is configured such that a negative pressure occurs in the exhaust gas bypass during operation of the exhaust gas system due to the exhaust gas flowing in the exhaust gas line. This can be done, in particular, using the law of Bernoulli known from fluid mechanics, according to which an increase in the velocity of a flowing fluid is accompanied by a pressure drop (this law is also used in the known suction jet or water-jet pumps). In accordance with a preferred variant of this embodiment based on this law, the exhaust gas inlet device has an orifice section whose line cross-section increases toward the outlet into the exhaust gas line, preferably in funnel shape. In this case, the mouth section extends into the exhaust gas system in such a way that its line cross section is thereby tapered. This results in the operation of the exhaust system to an increase in the velocity of the exhaust stream in the exhaust line and an associated pressure drop at the mouth of the exhaust inlet device. Thus, a negative pressure in the exhaust gas bypass is generated or promoted, which leads to the located at the other end of the exhaust gas bypass exhaust gas sampling device to suck the exhaust gas from the exhaust gas into the exhaust gas bypass, so that the supply of exhaust gas is conveyed to the condenser.

According to a further preferred embodiment, the device for condensate extraction further comprises an actuator for adjusting the exhaust gas flow rate in the exhaust gas bypass. The actuator may in particular be arranged on the exhaust gas extraction device. By means of the actuator, it is possible to regulate the amount of exhaust gas supplied to the condenser so that on the one hand, the condenser does not overheat, whereby the condensation would be difficult or even prevented, and on the other hand enough exhaust gas is passed into the exhaust gas bypass to the, in particular one Water injection system to win the internal combustion engine required amount of condensate. In a preferred embodiment of the invention, the actuator can be controlled by means of a control or regulating device, so that the position of the actuator can be adjusted as a function of one or more parameters. These parameters may in particular characterize an operating state of the internal combustion engine, a water injection system for the internal combustion engine, the exhaust system or the device for condensate recovery or the level of a water reservoir. In particular, the temperature of the exhaust gas in the exhaust line, the internal combustion engine or its cooling water, the speed of the internal combustion engine, the outside temperature or the water injection rate of the water injection system may be such suitable parameters. In a preferred development of this embodiment, the control or regulating device is configured to determine the exhaust gas rate in the exhaust gas line (ie exhaust gas mass per time) via the charge exchange, in particular on the basis of speed and degree of charging or load. In this case, in particular, the exhaust-gas temperature at the exhaust-gas outlet of the exhaust-gas system can also be determined at least roughly (eg to approximately 70 °). The control device may be further configured to determine the performance data of the radiator. Taking into account the outside temperature as a further parameter and optionally also the vehicle speed, the control device can then model based determine an optimal value or range of exhaust gas rate at which the condenser can efficiently cool the exhaust gas, without this passes through the dew point, ie without that the condensation essentially comes to a standstill. For this purpose, according to preferred variants, in particular with regard to an optimization of the condensate or water yield in the condensation, the following model principles Determination of the optimum value or value range for the exhaust gas rate is used:
In the first model, the exhaust gas rate, ie the exhaust gas mass flow is determined, from which also the pressure at the exhaust gas sampling device, ie at the bypass inlet, and the negative pressure at the exhaust gas inlet device, ie at the bypass outlet can be calculated. Likewise, the temperature at the cooler, from which it must be cooled, can be determined from this. In the second model, the cooling capacity is determined, which is achievable under the given environmental conditions, which include in particular the outside temperature and the vehicle speed (air inflow). If the maps calculated from the two models are then adjusted, it is possible to prevent too high temperatures in the condenser via a corresponding control or regulation of the exhaust gas rate in the bypass.

According to a further preferred embodiment, at least the surfaces of the exhaust gas bypass intended for contact with the condensate to be recovered are formed from a (chemically) corrosion-resistant material. These surfaces come into contact with the exhaust gas itself, the liquid water obtained by condensation and also possibly contained therein also liquefied impurities. The condensate may in particular be acidic and thus be particularly corrosive with respect to unprotected metal surfaces. With the help of the corrosion-resistant material, corrosion and thus damage to the apparatus for condensate extraction can be avoided, but in any case be delayed. Suitable corrosion-resistant materials are, in particular, zinc, aluminum, titanium, stainless steel or corrosion-resistant nickel-base alloys, in particular with chromium addition (for example the material "Inconel" from Special Metals Corporation). The corrosion-resistant material may in particular be present only on the surfaces exposed to the exhaust gas and the condensate. Alternatively, the apparatus for condensate recovery or individual components thereof may be formed entirely of such a material. Any mixtures or combinations of these two alternatives are possible.

According to a further preferred embodiment, the device for condensate extraction further comprises a heat insulating element for arrangement between the muffler and the condenser. The heat insulating element may in particular be a heat shield. Preferably, the heat insulation element between the muffler and a cooling loop of the capacitor, particularly preferably also disposed between the muffler and a collecting container for recovered condensate. Appropriately, the heat insulating element is at least one side, preferably separated on both sides by an air gap from the muffler, or the device for condensate recovery. In this way, the thermal insulation between the muffler and the apparatus for condensate recovery and thus the efficiency of the condensate recovery can be further improved.

A "cooling loop" in the sense of the invention means a fluid line which is adapted to cool by means of physical, in particular thermal interaction with its surroundings and / or by means of radiation a fluid present in the fluid line. The cooling loop can take any suitable forms and in particular have one or more curved sections. As a result, the fluid line can preferably also have a plurality of loop sections lying next to one another.

According to a further preferred embodiment, the condensate recovery device further comprises a condensate collecting vessel arranged in the exhaust gas bypass. In this case, the condenser has a cooling loop for cooling at least part of the partial exhaust gas flow. The cooling loop has a lower end connected to the receptacle and an upper end connected to the exhaust gas inlet device or the exhaust gas inlet device. The cooling loop is formed at least between its lower end and its upper end so that in the cooling loop by means of the cooling liquid condensate recovered from the partial exhaust gas flow can drain into the collecting container due to gravity. In this way, the condensate obtained in the cooling loop by cooling the exhaust gas can automatically, and without the need for an active condensate conveying device, such as a pump, get into the collecting container automatically.

According to a first preferred embodiment of this embodiment, the upper end of the cooling loop is connected to the exhaust gas removal device, and the cooling loop is arranged in Teilabgasstromrichtung before the collecting container, so that the recovered liquid condensate can drain in the direction of the partial exhaust gas flow into the collecting container. In this way, the initially high temperature of the exhaust gas can be used to overcome a difference in height between the inlet mouth of the exhaust gas removal device and the beginning of the cooling loop. Another advantage is that the condensate formed during the cooling can flow in the flow direction of the partial exhaust gas flow in the cooling loop to the collecting container, so that the exhaust gas flow further promotes the drain, but at least does not hinder. For this purpose, the exhaust gas removal device According to a preferred variant of a riser, which connects the entrance mouth of the exhaust gas removal device on the exhaust line to the upper end of the cooling loop and can ascend in the hot exhaust gas before it enters the cooling loop. Particularly preferably, the riser is substantially rectilinear.

According to a second alternative development of this embodiment, however, the upper end of the cooling loop is connected to the exhaust gas inlet device and the cooling loop is arranged in Teilabgasstromrichtung after the collecting container, so that the recovered liquid condensate can drain contrary to the direction of the partial exhaust gas flow into the collecting container. This second development is particularly advantageous if, in addition to the condensate recovery in the condenser, a collection of condensate to be accomplished, which has collected in the exhaust gas flow direction before the muffler in the exhaust system. Particularly in the case of motor vehicles, driving profiles, which in the meantime frequently occur during everyday driving, in which condensation deposits occur in the exhaust system of the exhaust system of the internal combustion engine of the vehicle. This may in particular be the case when the exhaust system is still cold or when it can not be heated by suitable environmental conditions above a certain temperature (dew point for water vapor in the exhaust gas). Low outside temperatures or cooling air currents can further promote this. Even long service lives or short distances are conditions under which condensation can easily settle in the exhaust system.

According to a preferred variant of this development, the collecting container is arranged on the exhaust gas removal device or is a part of this. It has a fluid inlet, by means of which it can be connected to a section of the exhaust system of the exhaust system which is located upstream of the muffler, preferably in the exhaust gas flow direction, such that a fluid stored there is in the exhaust gas flow direction, due to gravity or an acceleration component directed counter to the exhaust gas flow direction a movement of the exhaust system, can flow through the liquid inlet from the exhaust line into the collecting container. Especially in a motor vehicle, the acceleration component may be caused by its accelerated movement. In this case, the liquid inlet can preferably simultaneously serve as an exhaust gas inlet opening of the exhaust gas removal device. Furthermore, with regard to the best possible sound damping, it may also be advantageous in the exhaust gas bypass if the fluid inlet has at least one fluid-permeable, sound-damping acoustic element. The acoustic element may in particular have a perforated metal sheet which at least partially covers the exhaust gas inlet opening of the exhaust gas sampling device, wherein the perforation is designed such that it is permeable to both exhaust gas and exhaust gas condensate or water.

According to a further preferred embodiment, the condensate recovery device further comprises at least one of the following cooling boosting devices to aid in the recovery of condensate: cooling fins, in particular at the cooling loop, at the catch tank, or at both; or one or more louvers for selectively directing air currents to the condensate recovery device, in particular the cooling loop or the receiver, or both. By means of the cooling fins, the cooling surface available for cooling, in particular air cooling, of the condenser or its cooling loop and optionally the collecting container is increased, so that a stronger or more efficient cooling and thus improved condensate extraction is made possible. On the other hand, with air cooling, an air flow, in the case of vehicles, in particular the airstream, is specifically directed to the elements to be cooled of the device for condensate extraction via the air guiding devices, which may be air baffles in particular. This in turn promotes a stronger or more efficient cooling and thus condensate recovery.

According to a further preferred embodiment, the device for condensate extraction further comprises a liquid extraction device for removing liquid from the collecting container. In this case, the liquid sampling device is controlled in response to a control signal, in particular activated and deactivated, which depends on at least one of the following parameters: the filling state of the collecting container, the filling of a to be fed from the collecting container storage tank; the operating state of the internal combustion engine, in particular its load state; the operating state of the exhaust system, in particular its temperature or exhaust gas pressure; from an acceleration of the exhaust system. In this way, it is advantageously possible to make the removal of liquid, ie, depending on the embodiment of condensate from the condenser and / or from the exhaust line, from the collecting container only if enough liquid is present, or to adapt the removal amount to the consumption of the liquid , Or schedule the withdrawals so that the liquid distribution in the collecting container at a given acceleration and the associated forces for liquid removal is particularly favorable. The latter can be achieved, for example, in which a liquid extraction hose or tube to a rear end of the collecting container is arranged so that at a forward acceleration of the liquid level in the rear part of the collecting container increases, which is particularly favorable for a particular bubble-free liquid removal at this point.

A second aspect of the invention relates to an exhaust system for an internal combustion engine, in particular for an internal combustion engine of a motor vehicle. The exhaust system has an exhaust line with at least one silencer and a device for condensate extraction according to the first aspect of the invention.

Therefore, what has already been stated above for the condensate recovery device according to the first aspect of the invention applies equally to the exhaust gas system according to the second aspect of the invention.

According to a preferred embodiment of the exhaust system, this is provided for an internal combustion engine of a motor vehicle and the condenser, in particular a cooling loop of the condenser, is arranged in the exhaust system relative to the muffler so that when driving forward of a motor vehicle equipped with the exhaust system of the wind first on the condenser meets before hitting the muffler. This can be accomplished, in particular, by arranging the muffler in the exhaust system closer to an end orifice of the exhaust system, in particular to one or more tailpipes, than the condenser. So comes the latter when installing the exhaust system in a vehicle closer to its front to lie down than the muffler. In this way, the cooling in the condenser is not adversely affected by the waste heat of the exhaust gas heated by the exhaust gas, which promotes the efficiency of the cooling and thus the condensate recovery.

According to a further preferred embodiment, the exhaust system is designed as underfloor exhaust system of a motor vehicle, wherein the cooling of the capacitor, optionally also a collecting container for the condensate obtained by means of air cooling by the driving wind.

According to a further preferred embodiment, the cooling of the condenser can take place at least partially by means of a liquid cooling circuit, in particular by integrating a corresponding heat exchanger provided for cooling the exhaust gas or the condenser into the condenser.

According to a further preferred embodiment, in which the exhaust system is designed as an exhaust system of a motor vehicle, located in the exhaust gas flow direction upstream of the exhaust gas removal device region of the exhaust line is formed so that it has at least a portion which is lower than an exhaust gas inlet opening of the muffler. In this way, a condensed in the exhaust system during or after a trip condensate in this section can collect, with a flow into the muffler is made difficult by the lower layer. In this way, on the one hand by unwanted noise generated by liquid entry in the muffler limit or even avoid. On the other hand, if the condensate recovery device is provided with a liquid inlet to a collecting container as described above, the condensate collected in the section can flow into it and thus likewise contribute to condensate extraction.

Further advantages, features and possible applications of the present invention will become apparent from the following detailed description taken in conjunction with the figures.

It shows

1 schematically in a front side view (seen from an associated internal combustion engine) of an exhaust system with a muffler and a device for condensate recovery, according to a first preferred embodiment of the invention, in which the directions of the exhaust gas flow and the condensate flow in the condenser coincide;

2 schematically in a front side view (of an associated internal combustion engine from an exhaust system with a muffler and a device for condensate recovery, according to a second preferred embodiment of the invention, in which the directions of the exhaust gas flow and the condensate flow in the condenser in opposite directions;

3 schematically a detailed end view of an exhaust system according to the principle of 2 in accordance with a preferred embodiment of the invention;

4 schematically a detailed front side view (of an internal combustion engine) of the exhaust system 3 ;

5 schematically a preferred embodiment of the exhaust system 4 with cooling fins on the condenser on the collecting container; and

6 schematically condensate storage system for combination with the device for Condensate recovery, according to a preferred embodiment of the invention.

Hereinafter, the same reference numerals for the same or corresponding features used throughout.

First, it will open 1 Reference is made to an exhaust system 1 is shown according to a first preferred embodiment of the invention. The exhaust system 1 has a silencer 2 on, in particular, be a rear muffler and can be arranged in the exhaust system of an internal combustion engine. Furthermore, the exhaust system 1 a multi-component device for condensate recovery. Between the internal combustion engine and the muffler extends an exhaust line, which is an internal combustion engine side exhaust pipe 3 with an inlet opening 4 for coming from the engine exhaust gas. In particular, one or more further mufflers, as well as other elements of an exhaust system, in particular a catalyst or exhaust gas filter, can be found in the exhaust gas system. At the exit of the muffler 2 at least one output-side exhaust pipe is arranged, in the illustrated example of a dual-flow exhaust system 1 are two each formed as tailpipes output side exhaust pipes 5a and 5b available. The condensate recovery device has an exhaust gas removal device 6 on which at an upper side of the exhaust pipe 3 attaches to divert exhaust gas from it. Preferably, the exhaust gas removal device 6 an actuator in order to adjust the gas withdrawal rate of the branched gas variable. The exhaust gas removal device 6 thus acts as a branch or switch, which is the exhaust gas coming from the engine in a through the muffler 2 separating main exhaust gas stream and the branched partial exhaust gas stream.

To the exhaust gas removal device 6 joins a riser, which in a down in several loops, acting as a capacitor cooling loop 11 merges into a, preferably arranged at the level of the underside of the muffler, collecting container 8th for condensate opens. At an upper end of the collection container 8th begins a connection line 7 , which initially also rises and after the muffler in one of (optionally in both) tailpipes 5a respectively. 5b by means of an exhaust gas inlet device 12 empties. Thus, between the exhaust gas removal device 6 at the exhaust pipe 3 and the exhaust inlet device 12 at the tailpipe 5a respectively. 5b (not shown) formed a continuous exhaust passage, which acts as a bypass to exhaust gas on the muffler 2 over into the tailpipe (s) 5a respectively. 5b to lead.

The cooling loop 11 is coolable, in particular by means of an air flow, as occurs when driving a motor vehicle, so that the water vapor present in the exhaust gas passed through it at least partially condenses to liquid water when it is cooled below its dew point. In addition to water, this condensate can also contain additional substances as impurities, in particular further exhaust gas constituents. As the individual sections of the cooling loop 11 represent a downwardly extending, angled ramp, the liquid condensate obtained by cooling by gravity along the cooling loop into the receptacle 8th Expire and be collected there. The uncondensed exhaust gas of the partial exhaust gas flow passes through the entire bypass of the exhaust gas extraction device 6 over the cooling loop 11 , the collection container 8th and the connecting pipe 7 to the exhaust inlet device 12 in the tailpipe 5a respectively. 5b without losing the muffler 2 to go through. Accordingly, in this embodiment, the directions of the partial exhaust gas flow and the condensate flow in the condenser are the same. To remove the condensate obtained from the collecting container 8th is a suction device 9 with a subsequent sales hose 10 provided over which the condensate can be sucked.

In 2 is an alternative exhaust system 1 represented according to a second preferred embodiment of the invention. The structure of this exhaust system 1 mostly agrees with that 1 match. The main difference, however, is the arrangement of the cooling loop 11 as well as the connection line 7 , In 2 begins the connection line 7 on the exhaust gas removal device 6 at the exhaust pipe 3 and runs, preferably substantially rectilinear and sloping, to the collecting container 8th , The cooling loop 11 of the capacitor starts at the collecting tank 8th above the mouth of the connecting pipe 7 and rises, preferably in several turns, at an angle until after a falling portion in one or both of the tailpipes 5a respectively. 5b by means of an exhaust gas inlet device 12 empties. In the cooling loop 11 In turn, condensate can separate out of the exhaust gas when cooled, which due to the oblique course of the cooling loop due to gravity to the collecting container 8th drain and can collect there (the same applies accordingly to condensate, which may be in the connecting line 7 Accordingly, in this embodiment, the directions of the partial exhaust gas flow and the condensate flow in the cooling loop 11 in opposite directions.

In 3 schematically is a detailed end view of an exhaust system 1 according to the principle 2 shown. On the right side is the coming from the engine exhaust pipe 3 to see the exhaust line, which in increasing angle to the muffler 2 leads and flows into these. At the exit of the muffler 2 is one of the tailpipes 5a to see. The exhaust gas removal device 6 is formed as a funnel shape, whose opening at the rising angle portion of the exhaust pipe 3 so attaches that one in the exhaust pipe 3 liquid accumulated in front of the funnel 17 must cross a threshold to get into the funnel. At the pointed end of the funnel of the exhaust gas removal device 6 closes a collecting container 8th for condensate, so that a liquid entering the funnel is forced into the collection container due to gravity 8th expire and can be collected there. Accordingly, if there is a tilting or acceleration of the exhaust system or the liquid level of the liquid 17 so high that it exceeds the threshold, then the liquid can 17 in the collection container 8th arrive (see arrow) and be collected there. This is particularly advantageous when the exhaust system 1 Part of an exhaust system of a motor vehicle. Then condensate, which has collected in the exhaust system, collected with appropriate acceleration or uphill drive of the vehicle and thus as a recyclable liquid, in particular for water injection into the internal combustion engine, can be obtained. The exhaust gas removal device may be to the exhaust pipe 3 with a condensate-permeable but sound-absorbing acoustic element 15 , in particular with a perforated sheet, be provided to attenuate unwanted noise, which otherwise fails, in particular by the bypass to the tailpipes 5a respectively. 5b and from there to the environment could propagate.

According to the already related to 2 explained construction principle, closes at the top of the collection container 8th a capacitor with a cooling loop 11 on, in the one about the exhaust gas removal device 6 from the exhaust pipe 3 diverted partial exhaust gas flow is guided upward and thereby cooled. When cooling below the dew point of water thereby water-containing condensate is deposited, which gravitationally on the inclined portions of the cooling loop 11 down into the collection container 8th runs and there as condensed condensate 16 is available for further use.

After passing through the cooling loop 11 the remaining partial exhaust gas flow becomes an exhaust gas inlet device 12 at the tailpipe 5a where it is reunited with the main exhaust gas stream, which was previously the muffler 2 has gone through. The exhaust inlet device 12 points to one in the tailpipe 5a extending funnel-shaped mouth opening, wherein the funnel in the direction of the partial exhaust gas flow to the mouth of the tailpipe 5a opens and thus at this point the cross section of the tailpipe 5a reduced. In this way, the law of Bernoulli comes into play, according to which forms at the mouth of the funnel, a negative pressure, which in the at the exhaust inlet device 12 propagating bypass and thus generates a suction effect, due to which the partial exhaust gas flow through the between the exhaust gas removal device 6 and the exhaust inlet device 12 and over the cooling loop 11 extending bypass is pulled. Preferred is a corresponding dimensioning of the exhaust gas removal device 6 and / or the exhaust inlet device 12 and the intermediate bypass or via an optional actuator, such as the exhaust gas removal device 6 , the amount of gas of the partial exhaust gas flow determined so that during normal operation, on the one hand enough exhaust gas flows through the bypass, so that a sufficient amount of condensate can be deposited in the cooling loop, and on the other hand, the amount of heat transported by the partial exhaust gas flow is not so high that they the condensation process of Cooling loop significantly negatively affected due to excessive heat input. Here, a dynamic control or regulation of the partial exhaust gas flow by means of said actuator is possible to situationally, in particular depending on the temperature, to control or regulate the strength of the partial exhaust gas flow.

For at least extensive thermal decoupling of the muffler 2 on the one hand and the capacitor, in particular the cooling loop 11 , as well as the collection container 8th On the other hand, there is a heat insulating member in between 14 by means of spacers 13 on the muffler 2 appropriate. The heat insulation element 14 is on both sides by an air gap from the muffler 2 or the capacitor is disconnected. It may be formed in particular as a shielding plate.

In 4 is the exhaust system 1 out 3 shown again, but this time again in a front side view of the engine.

In 5 is a preferred development of in 3 and 4 shown exhaust system shown. Here, to increase the cooling capacity of the condenser cooling fins 18a and 18b in the area of the cooling loop 11 and the collection container 8th provided to increase the effective cooling area of the capacitor. Alternatively, the cooling fins may also selectively only on the cooling loop 11 or at the collecting container 8th be provided. Otherwise corresponds to the exhaust system 1 out 5 already in connection with the 3 and 4 described exhaust system.

In 6 a condensate storage system for combination with the apparatus for condensate recovery is shown, which is an extension of the exhaust system according to the invention 1 can be. Accordingly, one or more components thereof, preferably all components of the exhaust system 1 be. The condensate storage system is with the collecting container 8th connected to the device for condensate recovery, so that from the collecting container 8th There existing condensate can be removed, in particular via suction. Accordingly, this connection can in particular by means of a suction 19 take place, which can be preferably designed as a pipe or hose.

For conveying the condensate from the collecting container 8th is the exhaust pipe 19 with a pump 21 connected, in turn, with a storage tank 22 connected to the extracted condensate in the storage tank 22 to pump. In the connection between the intake manifold 19 and the pump 21 and / or the connection between the pump 21 and the storage tank 22 can be a filter 20a respectively. 20b for cleaning the container 8th be removed condensate. The filter may preferably be replaceable. It is also conceivable that it contains one or more sacrificial elements that allow neutralization of acids contained in the condensate. By contrast, measures to remove limescale from the condensate are normally not required due to the preceding condensation, although not excluded. The collection container 8th can be a level sensor 26 exhibit. Likewise, the storage tank 22 a level sensor 23 exhibit. In this way, the levels that can be measured with it can be used individually or together in each case in order to accomplish an adapted operation of the condensate storage system. In particular, the condensate storage system based on the measured levels can be operated so that the pump is activated only when in the collection container 8th condensate collected or that a removal of condensate from the storage tank 22 , For example, by another pump (not shown) only takes place when it is at least partially filled.

The storage tank 22 can optionally have a filler neck 24 by means of which it can be refueled with a liquid, in particular water. This can be advantageous in particular when the condensate provided by the apparatus for condensate extraction is at least temporarily insufficient or, for example, eliminated due to a defect. Finally, the storage tank 22 another overflow device 25 on, by means of the filled storage tank 22 superfluous condensate or water and also from the pump 21 sucked exhaust fumes can be derived.

While previously described at least one exemplary embodiment, it should be understood that a large number of variations exist. It should also be understood that the described exemplary embodiments are nonlimiting examples only and are not intended to thereby limit the scope, applicability, or configuration of the devices and methods described herein. Rather, the foregoing description will provide those skilled in the art with guidance for implementing at least one example embodiment, it being understood that various changes in the operation and arrangement of the elements described in an exemplary embodiment may be made without departing from the scope of the appended claims deviated from, and its legal equivalents.

LIST OF REFERENCE NUMBERS

1

exhaust system

2

Silencer, in particular rear silencer

3

Engine side exhaust pipe

4

Inlet opening of the engine exhaust pipe

5a, b

Output side left and right exhaust pipe, in particular tailpipe

6

Exhaust gas sampling device, in particular with actuator

7

connecting line

8th

receptacle

9

Suction device for collected liquid

10

suction hose

11

cooling loop

12

Exhaust inlet device, in particular also liquid inlet

13

spacer

14

Heat insulation element, in particular shielding plate

15

Sound-absorbing acoustic element, in particular perforated sheet metal

16

Collected condensate, in particular from cooling loop and exhaust pipe

17

Condensate collected in the engine exhaust pipe

18a, b

Cooling fins for condenser / cooling loop or collecting container

19

suction

20a, b

filter

21

pump

22

storage tank

23

Level sensor for storage tank

24

Filler neck for storage tank

25

Overflow device for storage tank

26

Level sensor for collecting container

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

• WO 01/92710 A1 [0004]
• DE 102012207903 A1 [0005]

Claims (15)

Device for collecting condensate from an exhaust system of an internal combustion engine, in particular for obtaining water for a water injection system of an internal combustion engine of a motor vehicle, comprising: a condenser ( 11 ) for condensing water vapor present in the exhaust gas of the internal combustion engine into liquid water; one in exhaust gas flow direction in front of a silencer ( 2 ) of the exhaust system in an exhaust line ( 3 ) the exhaust system provided exhaust gas sampling device ( 6 ) for diverting a partial exhaust gas flow from the exhaust system and for supplying the diverted partial exhaust gas flow into the condenser ( 11 ); one in exhaust gas flow direction after the muffler ( 2 ) in the exhaust gas line ( 5a , b) provided exhaust gas inlet device ( 12 ) for the return of exhaust gas of the branched exhaust partial flow into the exhaust gas after its passage through the capacitor ( 11 ); wherein the condensate recovery device is an exhaust gas bypass ( 6 . 7 . 8th . 11 . 12 ) forms to the exhaust gas partial flow from the exhaust line ( 3 ) to remove it for condensate extraction, bypassing the muffler ( 2 ) through the outside of the muffler ( 2 ) arranged capacitor ( 11 ) and guide it in the exhaust gas flow direction behind the silencer ( 2 ) back into the exhaust system ( 5a , b) return. Condensate recovery device according to claim 1, wherein the exhaust gas extraction device ( 6 ) is configured so that at her during operation of the exhaust system by the in the exhaust line ( 3 ) flowing exhaust gas creates a back pressure. Condensate recovery device according to one of the preceding claims, wherein the exhaust gas inlet device ( 12 ) is configured so that at her during operation of the exhaust system by the in the exhaust line ( 5a , b) inflowing exhaust gas a negative pressure in the exhaust gas bypass ( 6 . 7 . 8th . 11 . 12 ) occurs. A condensate recovery apparatus according to any one of the preceding claims, further comprising an exhaust flow rate adjusting actuator in the exhaust gas bypass ( 6 . 7 . 8th . 11 . 12 ). Condensate recovery device according to one of the preceding claims, wherein at least the surfaces of the exhaust gas bypass provided for contact with the condensate to be recovered ( 6 . 7 . 8th . 11 . 12 ) are formed of a corrosion resistant material. A condensate recovery apparatus according to any one of the preceding claims, further comprising a heat insulating member (10). 14 ) for the arrangement between the silencer ( 2 ) and the capacitor ( 11 ). Condensate recovery apparatus according to any one of the preceding claims, further comprising one in the exhaust gas bypass ( 6 . 7 . 8th . 11 . 12 ) arranged collecting container ( 8th ) for condensate; wherein the capacitor is a cooling loop ( 11 ) for cooling at least part of the partial exhaust stream, and the cooling loop ( 11 ) with the collecting container ( 8th ) and a lower end connected to the exhaust gas sampling device ( 6 ) or the exhaust gas inlet device ( 12 ) has connected upper end; and the cooling loop ( 11 ) is formed at least between its lower end and its upper end so that in the cooling loop ( 11 ) obtained by the cooling of the partial exhaust gas liquid condensate due to gravity in the collecting container ( 8th ) can expire. Condensate recovery apparatus according to claim 7, wherein the upper end of the cooling loop ( 11 ) with the exhaust gas sampling device ( 6 ), and the cooling loop ( 11 ) in Teilabgasstromrichtung before the collecting container ( 8th ) is arranged so that the recovered liquid condensate in the direction of the partial exhaust gas flow into the collecting container ( 8th ) can expire. Condensate recovery apparatus according to claim 8, wherein the upper end of the cooling loop ( 11 ) with the exhaust gas inlet device ( 12 ) and the cooling loop ( 11 ) in Teilabgasstromrichtung after the collecting container ( 8th ) is arranged so that the recovered liquid condensate counter to the direction of the partial exhaust gas flow into the collecting container ( 8th ) can expire. Condensate recovery device according to claim 9, wherein the collecting container ( 8th ) at the exhaust gas sampling point ( 6 ) is arranged or is part of this and has a liquid inlet, by means of which it is arranged in front of the muffler in the direction of the exhaust gas ( 6 ), preferably in the exhaust gas flow direction rising, section of the exhaust line ( 3 ) of the exhaust system is connectable so that there is a stored liquid ( 17 ) in the exhaust gas flow direction, due to gravity or an acceleration component directed counter to the exhaust gas flow direction of movement of the exhaust gas system, through the liquid inlet from the exhaust gas line (US Pat. 3 ) in the collecting container ( 8th ) can flow. Condensate recovery device according to claim 10, wherein the liquid inlet at the same time as an exhaust gas inlet opening of the exhaust gas sampling device ( 6 ) serves. Condensate recovery device according to claim 10 or 11, wherein the liquid inlet comprises at least one fluid-permeable, sound-damping acoustic element ( 15 ) having. Condensate recovery apparatus according to any one of claims 7 to 12, further comprising at least one of the following cooling enhancement devices for promoting condensate recovery: cooling fins ( 18a , b), in particular on the cooling loop ( 11 ), at the collecting container ( 8th ), or at both; one or more louvers for selectively directing air flows to the condensate recovery device, in particular to the cooling loop ( 11 ) or the collecting container ( 8th ), or both. A condensate recovery apparatus according to any one of claims 7 to 13, further comprising a liquid sampling apparatus (10). 19 to 21 ) for removing liquid from the collecting container ( 8th ); the liquid extraction device ( 19 to 21 ) is controllable in dependence on a control signal which depends on at least one of the following parameters: - on the filling state of the collecting container ( 8th ) or a value calculated according to a model thereof; - the filling state of a storage tank to be fed from the collecting container ( 22 ); - The operating condition of the internal combustion engine, in particular its load condition; - The operating condition of the exhaust system, in particular its temperature or exhaust pressure; - of an acceleration of the exhaust system. Exhaust system for an internal combustion engine, in particular for an internal combustion engine of a motor vehicle, comprising: an exhaust gas system (US Pat. 3 . 2 . 5a , b) with at least one silencer ( 2 ); and a device for condensate extraction ( 11 ) according to one of the preceding claims, in particular for obtaining water for a water injection system of the internal combustion engine.

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