Exhaust pipe, combustion engine machine, and motor vehicle

Abstract

An exhaust pipe for the exhaust tract of a combustion machine, which has an inlet opening for an air connection, is characterized by an inner pipe section which is surrounded by an outer pipe section in order to form an annular channel that is closed at one end and at the other end is open toward the inner volume of the exhaust pipe, wherein the inlet opening for the air connection opens into the outer pipe section. By means of such an exhaust pipe, advantageous mixing of air supplied via the air connection into the exhaust gas flowing within the exhaust pipe can be achieved with a simple design, which can be attributed in particular to the complete introduction of the air in combination with the flow direction that is present along the longitudinal axis of the annular channel and the exhaust pipe.

Claims

1. An exhaust pipe for the exhaust tract of an internal combustion engine, the exhaust pipe having: an inlet opening configured for attachment to an air connection, and an inner pipe section that is surrounded by an outer pipe section to form an annular channel that is closed at one end and at the other end is open toward an inner volume of the exhaust pipe, wherein the inlet opening for the air connection is integrated into the outer pipe section, at least one flow guiding element for generating a swirl flow of the exhaust gas situated within the inner pipe section, wherein the at least one flow guiding element is in the form of a baffle plate that is oriented obliquely with respect to a longitudinal axis of the exhaust pipe, wherein the at least one flow guiding element is designed in the form of a deformed section of a pipe casing of the inner pipe section, wherein the pipe casing section has a triangular shape, and wherein a forming edge of the at least one flow guiding element extends helically with respect to a longitudinal axis of the inner pipe section, from a longitudinal opening that is introduced into the pipe casing and extends in a longitudinal direction of the inner pipe section.

2. The exhaust pipe according to claim 1, further comprising a first pipe section and a second pipe section, wherein an end section of the first pipe section is inserted into an end section of the second pipe section so that the two end sections form the inner pipe section and the outer pipe section.

3. The exhaust pipe according to claim 2, wherein the closed end of the annular channel is formed by a radially inwardly extending end edge of the second pipe section.

4. The exhaust pipe according to claim 3, wherein the radially inwardly extending end edge is designed as a deformed end piece of the second pipe section by plastic deformation of said end piece.

5. The exhaust pipe according to claim 1, wherein the inner pipe section adjoining one side of the at least one flow guiding element forms a through opening, wherein the inner pipe section is situated downstream with respect to a flow direction of the exhaust gas of the flow guiding element.

6. A combustion machine having the internal combustion engine and the exhaust tract for discharging exhaust gas from the internal combustion engine, wherein the air connection for introducing air into the exhaust tract is integrated into the exhaust tract, wherein the exhaust tract includes an exhaust pipe according to claim 1.

7. The combustion machine according to claim 6, further comprising a particulate filter integrated into the exhaust tract downstream from the air connection.

8. The combustion machine according to claim 6, further comprising an exhaust gas catalytic converter integrated into the exhaust tract upstream from the air connection.

9. The combustion machine according to claim 6, wherein the internal combustion engine has a spark ignition design.

10. A motor vehicle having a combustion machine according to claim 6.

11. The motor vehicle according to claim 10, further comprising a particulate filter situated beneath an underbody of the motor vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is explained in greater detail below with reference to exemplary embodiments that are illustrated in the drawings, which show the following:

(2) FIG. 1: shows a simplified illustration of a motor vehicle according to the invention;

(3) FIG. 2: shows a schematic illustration of a combustion machine according to the invention; and

(4) FIG. 3: shows a partial longitudinal section of an exhaust pipe according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows a motor vehicle according to the invention with a combustion machine 10 according to the invention.

(6) The combustion machine 10 according to FIG. 2 may include an internal combustion engine 12, in particular a gasoline engine, that forms a plurality of cylinders 14. The cylinders 14, together with pistons that are guided up and down and a cylinder head (not illustrated in either case), delimit combustion chambers in which fresh gas (primarily air) together with fuel is combusted, as the result of which the pistons are cyclically moved up and down. This movement of the pistons is transmitted in a known manner to a crankshaft, not illustrated, which is thus rotationally driven.

(7) The fresh gas is supplied to the internal combustion engine 12 via a fresh gas tract, and for this purpose is drawn in from the surroundings via an intake opening 16, purified in an air filter 18, and subsequently led into a compressor 20 which is part of an exhaust gas turbocharger. The fresh gas is compressed by means of the compressor 20, subsequently cooled in a charge air cooler 22, and with optional control by means of a throttle valve 24, supplied to the combustion chambers.

(8) The drive of the compressor 20 is provided by means of a turbine 26 that is integrated into an exhaust tract of the combustion machine and is likewise part of the exhaust gas turbocharger. Exhaust gas that is produced during the combustion of the fuel-fresh gas mixture in the combustion chambers of the internal combustion engine 12 is discharged from the internal combustion engine 12 via the exhaust tract, and initially flows through an exhaust gas catalytic converter 28 in the form of a 3-way catalytic converter, then through the turbine 26, and then through an exhaust pipe 30 according to the invention and into a particulate filter 32, and after flowing through a muffler (not illustrated) the exhaust gas is released to the environment. Due to the arrangement of the exhaust gas catalytic converter 28 close to the engine and due to the arrangement downstream from the turbine 26, on account of the limited installation space that is present in an engine compartment of the motor vehicle, it may be necessary to situate the particulate filter 32 beneath an underbody 80 of the motor vehicle (see FIG. 1).

(9) Flow through the turbine 26 results, in a known manner, in a rotating drive of a turbine impeller, which in turn is rotatably fixedly connected to a compressor impeller of the compressor 20 via a shaft 34. The rotating drive of the turbine impeller is thus transmitted to the compressor impeller. To limit the pressure buildup in the fresh gas tract during operation of the internal combustion engine 12 at high rotational speeds and high loads, the turbine 26 may be bypassed in a known manner by means of a so-called wastegate 36. Additionally or alternatively, a turbine with variable turbine geometry (VTG) may be used.

(10) The particulate filter 32 is used to filter particles, in particular soot particles, from the exhaust gas. This may result in the particulate filter 32 becoming clogged in the course of operation, which requires regeneration of the particulate filter 32 to prevent the exhaust gas back pressure created by the particulate filter 32 from becoming impermissibly high. For such regeneration, engine-internal measures are implemented during operation of the internal combustion engine 12, on the one hand to set relatively high exhaust gas temperatures, and on the other hand to increase the proportion of unburned hydrocarbons in the exhaust gas. The aim is to oxidize (post-combust) unburned hydrocarbons in combination with oxygen that is supplied to the exhaust gas shortly before reaching the particulate filter 32 in order to increase the temperature of the exhaust gas in the particulate filter 32, which has already cooled fairly substantially due to the relatively large distance of the particulate filter 32 from the internal combustion engine 12, to the extent that the desired oxidation of the soot particles in the particulate filter 32, and thus the regeneration of the particulate filter 32, can take place.

(11) The oxygen provided for this purpose, as a component of air, is supplied to the exhaust gas via an air connection 42 that is integrated into an exhaust pipe 30 according to the invention. The air is led over a connecting line 38, which diverges from the fresh gas tract downstream from the air filter 18, and via the air connection 42 opens into an inlet opening 40 in the exhaust pipe 30. Conveying of this air is assisted or brought about by means of a conveying device 44. The exhaust pipe 30 represents a section of the exhaust tract that is situated a relatively short distance upstream from the particulate filter 32.

(12) Such an exhaust pipe 30 may have the structural design illustrated in FIG. 3. This exhaust pipe 30 according to FIG. 3 includes a first pipe section 46, which has a constant inner and outer diameter over the longitudinal extension, and a second pipe section 48, which likewise has a constant inner and outer diameter over the longitudinal extension. The two pipe sections 46, 48 have a curved design. An end section 52 of the first pipe section 46, in the direction along its longitudinal axis 50 and in a coaxial configuration, is inserted into an end section 54 of the second pipe section 48. This end section 52 of the first pipe section 46 represents an inner pipe section 56, and the end section 54 of the second pipe section 48 represents an outer pipe section 58, of the exhaust pipe 30. An annular channel 60 is formed between the two end sections 52, 54 or pipe sections 56, 58, since the inner diameter of the second pipe section 48 is larger, by a defined extent, than the outer diameter of the first pipe section 46.

(13) This annular channel 60 is formed on the end situated upstream from the (flow) direction provided for the flow of the exhaust gas 62, and is thus closed with respect to the surroundings. For this purpose, it is provided that a bent end piece 64 of the second pipe section 48 forms a radially inwardly extending end edge 66, which on the inner side contacts the outer side of the first pipe section 46 and is sealingly connected, for example soldered, welded, or adhesively bonded, thereto. In contrast, the annular channel 60 is open on the end situated downstream from the flow direction of the exhaust gas 62, and thus within the exhaust pipe 30, as the result of which air 68 that is supplied to the exhaust pipe 30 via the air connection 42 that is connected to the inlet opening 40 may be initially completely distributed within the annular channel 60, and from there may flow into the section of the second pipe section 48 downstream from the annular channel 60 with a flow direction that basically corresponds to the flow direction of the exhaust gas 62, and at that location the air 68 is mixed with the exhaust gas 62 that has flowed from the first pipe section 46 into the second pipe section 48, and may be supplied to the particulate filter 32 as an exhaust gas-air mixture 70.

(14) To achieve particularly advantageous intermixing of the air 68 with the exhaust gas 62, the inner pipe section 56 on the end situated downstream from the flow direction of the exhaust gas 62 forms a plurality of flow guiding elements 72 in the form of baffle plates oriented obliquely with respect to the longitudinal axis 50 of the exhaust pipe 30. These flow guiding elements 74 bring about swirl of the exhaust gas stream that flows through or around them, thus improving the mixing with the air 68 that is supplied on the edge side.

(15) The flow guiding elements 72 are distributed over the circumference of the inner pipe section 56 with an identical orientation and a uniform division. These flow guiding elements have been produced by introducing longitudinal openings 74, extending in the longitudinal axial direction with a uniform division and a defined length, in the form of separation cuts into the pipe casing formed by the end section 52 of the first pipe section 46. In each case a triangular section of this pipe casing has then been bent inwardly along a forming edge 76 that extends obliquely or helically about the longitudinal axis 50, wherein this forming edge 76, starting from the closed end of the associated longitudinal opening 74, extends to the end of the inner pipe section 56 or the end section 52 of the first pipe section 46 at which the longitudinal opening 74 runs out.

(16) Due to this type of design of the flow guiding elements 72, through openings 78 are at the same time formed in the pipe casing of the inner pipe section 56, in the slipstream of the flow guiding elements (with respect to the flow of the exhaust gas 62). As a result of these through openings 78, the air supplied to the exhaust pipe 30 may also partially flow into the stream of the exhaust gas 62 in directions extending obliquely with respect to that section of the longitudinal axis 50, and with swirl that is produced by the flow guiding elements 72, which likewise has a positive effect on the intermixing of the air 68 with the exhaust gas 62.

LIST OF REFERENCE NUMERALS

(17) 10 combustion machine 12 internal combustion engine 14 cylinder 16 intake opening 18 air filter 20 compressor 22 charge air cooler 24 throttle valve 26 turbine 28 exhaust gas catalytic converter 30 exhaust pipe 32 particulate filter 34 shaft 36 wastegate 38 connecting line 40 inlet opening in the exhaust pipe 42 air connection 44 conveying device 46 first pipe section 48 second pipe section 50 longitudinal axis of the first pipe section/second pipe section/exhaust pipe 52 end section of the first pipe section 54 end section of the second pipe section 56 inner pipe section 58 outer pipe section 60 annular channel 62 exhaust gas 64 end piece of the second pipe section 66 end edge of the second pipe section 68 air 70 exhaust gas-air mixture 72 flow guiding element 74 longitudinal opening 76 forming edge 78 through opening 80 underbody of the motor vehicle