DE102005034462A1 - Automotive internal combustion engine exhaust system with low-pressure zone co-located with ambient air inlet - Google Patents

Abstract

An automotive internal combustion engine has an exhaust system with a low-pressure zone in the vicinity of an ambient air inlet and sucks in cooling air. Also claimed are a particle filter, catalytic converter, silencer, exhaust pipe and exhaust gas tail pipe.

Description

The The invention relates to an exhaust system and a particle filter, a catalyst, a silencer, an exhaust pipe and an exhaust pipe for an exhaust system according to the Topics of the independent Claims.

When operating internal combustion engines in vehicles hot exhaust gases are generated, which usually reach the environment with high temperature. Various measures are known to reduce the temperature of the exhaust gases. For example, it has already been proposed to direct fresh air to an exhaust manifold via an air duct ( DE 101 47 624 A1 ). Alternatively, it has been proposed to additionally inject fresh air into the exhaust gas flow ( DE 198 47 477 A1 ), for which a separate exhaust gas cooling unit is provided ( DE 102 54 727 A1 ). Alternatively, it is known that a separate exhaust gas heat exchanger in the underfloor region is supplied with fresh air ( DE 101 25 989 A1 ).

Out the generic US-A-5,421,154 is an emission control system with an exhaust passage known by the exhaust gas of an internal combustion engine on a flow path dischargeable is, with the exhaust gas for cooling Fresh air can be supplied is. In this case, the internal combustion engine is a device with flame burner downstream, in the fresh air on the one hand for the combustion of Pollutants in the exhaust sucked with a fan, on the other hand for cooling the combustion exhaust gases of the flame burner at various points supplied to the device becomes.

Of the Invention is based on the object, an exhaust system with simple and space-saving design specify, in which the exhaust gas with reduced Temperature gets into the environment. Furthermore, a particle filter, a catalyst, a silencer, an exhaust pipe and an exhaust pipe for such exhaust system be created.

The The object is achieved by the Characteristics of the independent claims solved.

at an exhaust system according to the invention, in particular an exhaust gas purification system, with an exhaust passage, through the exhaust gas an internal combustion engine can be discharged into the environment on a flow path, is the exhaust gas for cooling Fresh air can be supplied, wherein the exhaust passage is structurally designed so that in the flow path of the exhaust gas by its flow a negative pressure range for sucking fresh air can be formed. For fresh air supply are no additional components such as fans and the like necessary; the suction can be done without active additional components simply accomplished and is purely passive. simultaneously a sufficient lowering of the exhaust gas temperature is achieved. Thereby can be a fire hazard and a risk of damage objects or injury to persons due to effluent gases. For suction, a suitable breakthrough is provided, preferably also as a flow pump-like Structure, in particular as Venturi nozzle, may be formed. Furthermore, the exhaust tract adjacent components in the vehicle against excessive temperature protected, which is a cheaper Material choice for allows these components. The effort for Thermal protection measures can be reduced. An intervention in a motor control or a Use of additional coolants can be omitted.

Cheap designs and advantages of the invention are the description and the other claims remove.

Does the Exhaust duct at least partially in and / or on a housing, which over a Breakthrough to a flow channel on a silencer and / or a cleaning stage and / or an exhaust tailpipe is, can a large-scale exhaust duct available made, which further cooling by convection on housing exterior surfaces at allowed simultaneously low exhaust gas velocity. Furthermore, can at the breakthrough a pipe, an exhaust pipe or the like, connect. A low exhaust gas velocity advantageously only causes one low dust uptake at the outlet of the exhaust gas from the exhaust system as well as a reduced heat accumulation on the road or a footprint of the vehicle, which the risk of fire is reduced. Through a large exit surface can a further reduction in the flow rate of the exhaust gas achieved and the convection effect can be improved. The cleaning stage For example, a particulate filter and / or a catalyst be. The breakthrough is preferably formed as large as possible. An exhaust gas cooling according to the invention can take place on a single component or also on several components, those in the flow path of the exhaust gas in the exhaust system are connected in series. Conveniently, is the breakthrough in the output range of the respective component intended.

Preferably, the housing is arranged with the exhaust duct as a trough-shaped body over the opening. As a result, a low overall height can be achieved with a large cross-section. It can alternatively or additionally vorgese hen that the housing is connected as a line, in particular exhaust pipe, pipe or channel to the opening.

In an advantageous development of the exhaust duct between envelopes of a multi-walled silencer, in particular a double-shell silencer arranged. Exhaust and Fresh air can specifically enter the space between the envelopes. existing Space can be used without making additional installations of components to have to. At the same time all Exterior surfaces of the silencer as convection surfaces be used.

One Vacuum range can be constructively created in a simple manner, when the flow path through a cross-sectional constriction in the exhaust duct leads and / or the flow path in the exhaust duct a change of direction experiences.

Preferably is adjacent to the vacuum area an opening for the intake of fresh air intended. This can be fed through a fresh air duct and / or be sucked through perforations. The opening is usefully upstream the negative pressure area, i. seen in the flow direction in front of the Low pressure area, arranged and preferably formed over a large area. This can a sufficient amount of fresh air for mixing with the Be sucked exhaust.

In a cheap one Design is the opening in the area of the silencer and / or the cleaning stage arranged. Alternatively or additionally the opening be arranged in the region of the exhaust pipe.

In In a preferred development, the exhaust gas channel at least in some areas a convection surface on. In particular special because of its large convection surface and after the mixing section in connection with the fresh air supply is this another way to lower the exhaust gas temperature. Convection surfaces are preferably provided on all outer surfaces.

is the flowpath in the mounted state on a side facing a lane the exhaust duct arranged, in particular in a lower area the silencer, a naturally very good ventilated Room, which allows efficient cooling by convection.

kick in the assembled state of the exhaust system in a vehicle, the exhaust gas from the exhaust duct at a shallow angle to an underbody of the Vehicle out, may additionally to the reduction of the flow velocity through a large-scale exhaust duct and a large-area outlet cross-section a further reduction of the dust upset and the risk of fire be achieved by the exiting exhaust.

Farther is an inventive silencer for an exhaust system equipped with a vacuum area as a mixing point for exhaust and fresh air.

One Particulate filter according to the invention for an exhaust system has a negative pressure area as a mixing point for exhaust gas and fresh air.

Further is in a catalyst according to the invention for one Exhaust system a negative pressure range as a mixing point for exhaust gas and fresh air provided.

Further is in an exhaust pipe according to the invention for one Exhaust system a negative pressure range as a mixing point for exhaust gas and fresh air provided.

Additionally or alternatively, an exhaust gas end pipe according to the invention preferably comprises at least approximately a flow pump type Structure, preferably a structure that in the manner of a Venturi nozzle in the outer sheath of the exhaust end pipe is arranged. If necessary, also at the exhaust pipe a housing, as described above, be provided or not. Farther the preferred embodiment of the exhaust tailpipe with the other, be combined or described embodiments above as a single measure be provided. Particularly advantageous is the preferred exhaust tailpipe for vehicles with diesel engines with exhaust aftertreatment, for example diesel particulate filters, Oxidation catalyst, SCR catalyst (SCR = selective catalytic reduction), which are known have at times very high exhaust gas outlet temperatures. Just Commercial vehicles often have, after the unit of rear silencer and exhaust aftertreatment, a very short tailpipe, through which the exhaust gas directly into the environment is directed. By introducing Venturi nozzles or powerheads in the exhaust pipe, the hot exhaust gas is bypassed ambient air added. Conveniently, The circumference of the exhaust end pipe has embossed slots which are venturi-like are formed and have a pointing into the interior of the exhaust pipe end imprint. In an advantageous embodiment, two diametrically opposite, relatively large Venturi nozzles on the circumference the exhaust end pipe is formed. Alternatively, a plurality of smaller Venturi nozzle, for example, eight Venturi nozzles, be evenly distributed on the circumference of the exhaust pipe.

In the following the invention is based on egg Nes described in the drawing embodiment explained. The drawing, the description and the claims contain numerous features in combination, which the person skilled in the art expediently also individually consider and summarize meaningful further combinations.

there show in a schematic representation:

1a , b; an exhaust tract of an internal combustion engine having a preferred exhaust system (a), variants of embodiment (b),

2 a side view of a preferred muffler with a housing with Frischluftansaugung

3 a plan view of the underside of the muffler 2 , and

4a , b; a preferred embodiment of a Abgasendrohrs with large Venturi nozzles (a) and circumferentially regularly distributed small Venturi nozzles (b).

In the figures are the same or substantially the same elements numbered with the same reference numerals.

The 1a . 1b show a rough schematic representation of an exhaust tract of an internal combustion engine 10 , As exemplified in 1a can be seen, an exhaust system, in particular a preferred emission control system, connected in series, a cleaning stage 11 as well as a silencer 12 on, in an exhaust pipe consisting of sections 14 . 15 . 33 are integrated. Although in the 1a . 1b For clarity, a single-flow exhaust system is shown, it is understood that the illustrated exhaust system, optionally in sections, can also be designed with two or more flooding.

A fuel-air mixture is supplied via a feed 13 in a known manner of the internal combustion engine 10 supplied there ignited and the exhaust gas via the line 14 to the cleaning stage 11 and then over the line 15 to the muffler 12 as well as via an exhaust pipe 33 to an exhaust tailpipe 35 passed, from which the exhaust finally exits. The cleaning stage 11 may comprise one or more catalysts and additionally or alternatively one or more particulate filters, in particular a soot particle filter. At the exit area of the cleaning stage 11 and the silencer 12 is a mixing point according to the invention 28 provided, is mixed at the fresh air with the hot exhaust gas. Of course, only the cleaning stage 11 or just the silencer 12 such a mixing point 28 exhibit. At the exhaust end pipe 35 is a flow pump-like structure 37 provided, is mixed with the fresh air with exhaust gas.

1b shows further possible embodiments of the embodiment in 1a , A preferred exhaust system has a silencer 12 on, before, in or after a cleaning step 11 in an exhaust pipe 14 . 15 . 33 can be integrated. A fuel-air mixture is supplied via a feed 13 in a known manner of the internal combustion engine 10 supplied there ignited and the exhaust gas via the line 14 to the muffler 12 or to the cleaning stage 11 with integrated silencer 12 and then over the line 15 passed, in which a muffler 12 can be arranged. The exhaust gas may be from the purification stage 11 and / or from the muffler 12 and / or out of the line 15 and / or the line 33 leak in the inventive manner cooled. The cleaning stage 11 may comprise one or more catalysts, alternatively or additionally one or more particulate filters, in particular a soot particle filter, and / or a silencer 12 , At the exit area of the cleaning stage 11 and / or the muffler 12 and / or on the line 15 and / or on the line 33 is a mixing point according to the invention 28 provided, is mixed at the fresh air with the hot exhaust gas. Of course, only the cleaning stage 11 or just the silencer 12 or just the line 15 or just the line 33 such a mixing point 28 exhibit. Again, a preferred exhaust tailpipe 35 with a flow pump-like structure 37 be provided.

A side view of a preferred silencer 12 with a housing 27 with fresh air intake with an exhaust duct 20 is in 2 exemplified. Accordingly, an inventive embodiment of a cleaning stage 11 ( 1a ) or the like. Alternatively or additionally, the principle can also be in one line 15 or a line 33 ( 1b ) be realized. Through the exhaust duct 20 is exhaust gas of an internal combustion engine 10 on a flow path 26 leachable, the exhaust gas for cooling at a mixing point 28 Fresh air can be supplied by the negative pressure in the exhaust duct 20 is sucked. The flow path 26 of the exhaust gas is through a series of consecutive arrows in the exhaust duct 20 indicated. The fresh air is through an arrow 31 marked and through an opening 30 in a housing 27 in the exhaust duct 20 introduced. To the opening 30 may be outside a fresh air duct or baffle 34 connect to suck in fresh air. The fresh air duct, the baffle 34 and / or the housing 27 can through open ends, perforations of all kinds the fresh air through the in a negative pressure Area 21 suck in previously generated vacuum.

The negative pressure forms after a spoiler edge 32 , caused by a cross-sectional constriction 22 in the flow path 26 , which in the exemplary embodiment by a slope 24 caused. Of course, other suitable measures for cross-sectional constriction or vacuum generation can be used.

The exhaust duct 20 runs in the housing designed as a flat, trough-shaped body 27 which is about a breakthrough 19 in a flow channel on an outer wall 29 of the muffler 12 is arranged. The exhaust gas passes through the large-area breakthrough 19 from the silencer interior into the housing 27 ,

Alternatively or additionally, it may be provided that the exhaust gas from the silencer interior in the line 13 and / or in the line 33 depending on where or at which point the silencer is located 12 is specifically arranged in the exhaust system. Of course, the exhaust duct 20 in his case 27 also alternatively or additionally in a cleaning stage 11 and / or in a pipe 15 and / or in a pipe 33 be arranged.

The exhaust gas flows in the mounted state of the muffler 12 in a vehicle at a shallow angle from the exhaust duct 20 a roadway or to an underbody of the vehicle, so that the least possible Staubaufwirbelungen in the outlet region of the exhaust gas and / or a reduced risk of fire is expected.

Of course, the exhaust gas alternatively or additionally from a cleaning stage 11 and / or a line 15 and / or a line 33 escape.

As in 3 It can be seen that a bottom view of the preferred muffler 12 from the 2 points to which the individual elements are explained is the opening 30 formed over a large area. All exterior surfaces of the housing 27 act as convection surfaces and improve the heat dissipation from the exhaust gas in addition to cooling by the intake fresh air. The exhaust duct 20 is in the mounted state on a side facing the roadway of the muffler 12 arranged so that the flow path 26 in a well-ventilated area and a heat removal via convection is particularly efficient. It can be seen that the case 27 is formed wide, so that the outlet cross section for the exhaust gas is relatively large (indicated by an arrow in arrow) and its flow rate is correspondingly low. As a result, a dust upset and / or a fire hazard in the exit area can be further reduced.

Furthermore, all outer surfaces of the housing 27 usable as convection surface.

4a and 4b represent a particularly preferred embodiment of the invention with reference to an exhaust tailpipe 35 that's on his outer coat 36 Indentations, the flow-pump-like structures designed as Venturi nozzles 37 Act. Exhaust gas, which is symbolized by an arrow flows in the figure left into the exhaust pipe 35 and is at the two diametrically opposed venturi nozzle-like structures 37 mixed with fresh air ( 4a ). The cooled mixture leaves the tailpipe 35 on the right side of the figure.

Alternatively, a plurality of preferably as Venturi nozzle flow pump-like structures 37 in the outer jacket 36 of the exhaust end pipe 35 be distributed. The distribution is preferably symmetrical, and the flow pump-like structures 37 can be circumferentially and axially offset from each other ( 4b ). The flow pump-like structures 37 can be made smaller in larger numbers than if only one or two flow pump-like structures 37 are provided.

Instead of invariable impressions with a fixed cross-sectional constriction to form the flow pump-like structures 37 can be provided variable cross-sectional constrictions. For this purpose, for example, in 2 illustrated slope 24 be made movable or adjustable. In this way, the formation of a variable opening width of the openings in the exhaust pipe 35 or in the case 27 allows. Advantageously, for example, the slope 24 power assisted pivotally perform. This makes it possible to adapt the generated negative pressure to the load point of the internal combustion engine or the exhaust gas flow rate. For example, via a tension or compression spring, a servomotor, a pressure cylinder or the like, the slope 24 be made adjustable depending on the engine operating point. In this way, sufficient negative pressure can be generated even at low load points with comparatively low exhaust gas flows in order to suck in sufficient fresh air for an effective cooling effect. By reducing the cross-sectional constriction at high load points by adjusting the slopes 24 An undesirable high exhaust back pressure can be avoided at these operating points.

Claims (23)

Exhaust system with an exhaust duct ( 20 ), by the exhaust gas of an internal combustion engine ( 10 ) on a flow path ( 26 ) can be discharged, wherein the exhaust gas for cooling fresh air can be supplied, characterized in that the exhaust duct ( 20 ) is structurally designed so that in the flow path ( 26 ) of the exhaust gas by the flow of a negative pressure range ( 21 ) can be formed for the intake of fresh air. Exhaust system according to claim 1, characterized in that the exhaust duct ( 20 ) at least partially in and / or on a housing ( 27 ) which passes over a breakthrough ( 19 ) in a flow channel on a silencer ( 12 ) and / or a cleaning stage ( 11 ) and / or an exhaust pipe ( 15 . 33 ) is arranged. Exhaust system according to claim 2, characterized in that the housing ( 27 ) as a trough-shaped body above the breakthrough ( 19 ) is arranged. Exhaust system according to claim 2 or 3, characterized in that the housing ( 27 ) as pipe, pipe and / or duct ( 15 . 33 ) to the breakthrough ( 19 ) connected. Exhaust system according to one of claims 2 to 4, characterized in that the exhaust duct ( 20 ) between casings of a multi-walled silencer ( 12 ) is arranged. Exhaust system according to one of the preceding claims, characterized in that the flow path ( 26 ) by a cross-sectional constriction ( 22 ) in the exhaust duct ( 20 ) leads. Exhaust system according to one of the preceding claims, characterized in that the flow path ( 26 ) in the exhaust duct ( 20 ) is changeable in its direction. Exhaust system according to one of the preceding claims, characterized in that adjacent to the negative pressure region ( 21 ) an opening ( 30 ) is provided for the intake of fresh air. Exhaust system according to claim 8, characterized in that to the opening ( 30 ) adjoins a fresh air channel. Exhaust system according to claim 8 or 9, characterized in that the opening ( 30 ) is formed by perforations. Exhaust system according to one of claims 8 to 10, characterized in that the opening ( 30 ) upstream of the negative pressure area ( 21 ) is arranged. Exhaust system according to one of claims 8 to 11, characterized in that the opening ( 30 ) is formed over a large area. Exhaust system according to one of claims 8 to 12, characterized in that the opening ( 30 ) in the area of the muffler ( 12 ) and / or the cleaning stage ( 11 ) is arranged. Exhaust system according to one of claims 8 to 13, characterized in that the opening ( 30 ) in the area of a line ( 15 . 33 ) is arranged. Exhaust system according to one of claims 9 to 14, characterized in that the exhaust duct ( 20 ) has at least partially one or more convection surfaces on outer surfaces. Exhaust system according to one of the preceding claims, characterized in that the exhaust duct ( 20 ) in the mounted state on a side facing the road surface of the muffler ( 12 ) and / or the cleaning stage ( 11 ) is arranged. Exhaust system according to one of the preceding claims, characterized in that in the mounted state in a vehicle, the exhaust gas from the exhaust duct ( 20 ) exits at a shallow angle to an underbody of the vehicle. Exhaust system according to one of the preceding claims, characterized in that the negative pressure region ( 21 ) by one or more flow pump-like structures ( 37 ), preferably venturi nozzle-like structures, can be produced. Exhaust pipe for an exhaust system according to one of the preceding claims, having a negative pressure region ( 21 ) as a mixing point ( 28 ) for exhaust and fresh air. Silencer for an exhaust system according to one of Claims 1 to 18, having a negative pressure region ( 21 ) as a mixing point ( 28 ) for exhaust and fresh air. Particulate filter for an exhaust system according to one of Claims 1 to 18, having a negative pressure region ( 21 ) as a mixing point ( 28 ) for exhaust and fresh air. Catalyst for an exhaust system according to one of Claims 1 to 18, having a negative pressure region ( 21 ) as a mixing point ( 28 ) for exhaust and fresh air. Exhaust end pipe for an exhaust system according to one of claims 1 to 18, having a negative pressure region ( 21 ) as a mixing point ( 28 ) for exhaust gas and fresh air, wherein circumferentially at least one flow pump-like structure ( 37 ), preferably one Venturi nozzle-like structure is arranged.