WO2023016695A1

WO2023016695A1 - Secondary air line for an exhaust tract of an internal combustion engine, having diodic valve loops

Info

Publication number: WO2023016695A1
Application number: PCT/EP2022/067785
Authority: WO
Inventors: Jeremy Weckering; Martin Heinrich; Stefan Schreiner; Alexander Zankl
Original assignee: Psa Automobiles Sa
Priority date: 2021-08-08
Filing date: 2022-06-28
Publication date: 2023-02-16
Also published as: DE102021208623A1

Abstract

Disclosed is a secondary air line (10) for a section (13) of an exhaust tract (17) of an internal combustion engine (19), comprising a main line (14) with main flow axes (151, 152, 153, 154) arranged at an angle to one another and with diodic valve loops (16), which have an inlet (11) and which extends in a fluid conducting manner from the main line (14), and an outlet (12), which is inclined at an exit angle (W12) with respect to the main flow axes (151, 152, 153, 154) and is connected to the main line (14) in a fluid conducting manner, wherein the inlet (11) and the outlet (12) are connected to one another in a fluid conducting manner inside the diodic valve loops (16).

Description

Title: SECONDARY AIR LINE FOR AN EXHAUST SYSTEM OF A

INTERNAL COMBUSTION ENGINE, HAVING DIODIC VALVE LOOPS

technical field

The disclosure relates to a secondary air line for an exhaust system of an internal combustion engine. A secondary air line that is used before or when an air-fuel mixture is enriched to blow in secondary air to reduce starting emissions can act as a resonator after the secondary air supply has been switched off, which can lead to resonance effects with undesired increases or decreases in temperature, pressure or Velocity curves in the secondary air duct itself and/or in the exhaust system close to the engine.

This can impair the function or energy efficiency of other components, e.g. turbochargers. This may require the use of additional components. This includes, for example, shut-off valves and the associated control concepts.

DE 10 2010 050 098 A1 relates to a heat exchanger with a hydrostatic flow valve. A flow valve without moving parts in use as a heat exchanger is disclosed. The flow valve uses dead water zones and cross-sectional changes in these zones for hydrostatic compensation of the pressure differences of the fluid flowing through in the different temperature zones.

Description

According to an object of the present disclosure, a secondary air line is to be specified with which the disadvantages mentioned above can be eliminated.

This object is achieved with a secondary air line according to claim 1. The dependent claims form advantageous developments of the disclosure. The dependent claims can be combined with one another in a technologically meaningful manner. The description, in particular in connection with the figures, additionally characterizes and specifies the disclosure. Accordingly, a secondary air line is provided for a section of an exhaust tract of an internal combustion engine, having a main line with main flow axes arranged at an angle to one another and with diode valve loops, which have an inlet which extends fluid-conducting from the main line, and an outlet which is inclined by an outlet angle with respect to the main flow axes. which is fluidly connected to the main line, the inlet and the outlet being fluidly connected to one another within the diode valve loops.

The main flow axes are arranged at an angle to one another, where the angle can be shallow. The use of a few diode valve loops represents a solution to reduce the undesirable flow or thermodynamic side effects in internal combustion engines, which does not affect the main function of the secondary duct. In addition, it does not require any moving components or additional control elements. Rule and control elements are robust with the prevailing temperature and pressure fluctuations in the exhaust system and are accordingly expensive. It is therefore advantageous if no regulating and control elements are necessary in the exhaust system.

A secondary air line is a structure that is designed to create a fluid-conducting connection between a secondary air fan and an exhaust tract of an internal combustion engine. A secondary air fan conveys air into the exhaust tract at operating points of the internal combustion engine in which it is operated with a rich mixture, so that remaining hydrocarbons in the catalytic converter can be oxidized. There are also solutions in which secondary air flows through a heating grid upstream of the catalytic converter in order to heat the catalytic converter.

The inlet is a position in the secondary air line at which the respective diode valve loop branches off in a fluid-conducting manner. The inlet can have the same cross-section as the main line. The inlet extends from the main line at an angle that is as flat as possible or without a change in direction, i.e. in a straight line. The main line bends by 20° to 40° at each valve loop.

The drain is a position in the secondary air line where a diode valve loop opens back into the main line. The drain can have the same cross-section as the main line.

Said section, in which the valve loops are arranged, is part of the secondary air line. There can be several sections, each with a diode valve loop be provided. The diode valve loops can also be staggered on opposite sides of the straight or curved main line. This is not shown in the exemplary embodiments.

The main line is the part of the secondary air line that provides a fluid-conducting connection between the secondary air pump and the exhaust tract. Air flows with a lower flow resistance from the secondary air pump to the exhaust tract and with a higher flow resistance from the exhaust tract to the secondary air pump. If no air is conveyed by the secondary air pump, not much exhaust gas can get into the secondary air line, since the flow resistance is higher in this direction. In addition, vibrations in the secondary air line are quickly reduced, since the increased flow resistance has a dampening effect. The secondary air pump is often located in the engine compartment next to the internal combustion engine. The secondary air line extends from the secondary air line to a portion of the exhaust tract downstream from the exhaust valves and upstream from the catalytic converter.

During operation of the secondary air pump, air flows along the main flow axes in the direction of the exhaust tract.

The diode valve loop is a loop integrated into the secondary air line, simply constructed and working without active components, which facilitates flow along the main flow axis in one direction and impedes it in the opposite direction.

In one embodiment, it is provided that a fluid-conducting extension of the inflow of the valve loop is continued along the main flow axes.

In one embodiment, a cross section of the valve loops is as large as a cross section of the main line, but at least 90% as large. This has proven advantageous over alternative designs. Valve loops with significantly smaller cross sections were tested in experiments. In this case, however, the cross section of the main line had to be enlarged in the area of the valve loop in order to achieve a low flow resistance in a conveying direction of the secondary air line. This increased cross-section means that the flow resistance is also reduced in the opposite direction to the conveying direction. Therefore, it has proven that the cross section of the valve loops corresponds to the cross section of the main line.

In one embodiment it is provided that a maximum of three diode valve loops are arranged in a secondary air line. Additional valve loops can be provided but this does not significantly increase the effect. Three valve loops have proven themselves in tests.

Measurements with the secondary air pump stopped show that a maximum flow speed of the fluid from the secondary air duct into the exhaust tract is reduced by 4% with three valve loops compared to two valve loops. This effect occurs almost constantly over an entire measured engine speed. The maximum flow rate of the fluid changes by more than 30% with two diode valve loops compared to a secondary air line without valve loops. Therefore, no major change is to be expected from the fourth valve loop.

In one embodiment, however, it is provided that a maximum of four diode valve loops are arranged in a secondary air line. As mentioned above, three valve loops may be sufficient in some applications and operating points of the internal combustion engine. With certain engine concepts, it can nevertheless be useful to provide a fourth valve loop. Although each additional valve loop increases the flow resistance against the flow direction, it also causes an increase in the flow resistance in the actual flow direction during operation of the secondary air pump. A favorable compromise can be achieved with four valve loops.

In one embodiment it is provided that three diode valve loops are arranged on an outside of a curved section, which the secondary air line describes between a secondary air pump and the exhaust tract, and a fourth diode valve loop is arranged on an inside of the curved section. The damping effect of this fourth valve loop in one direction can be increased by arranging the fourth "opposite" of the first three valve loops on the secondary air line, i.e. on the other side of the main line. The fourth main flow axis is also arranged at an angle to the third main flow axis, but is oriented in the opposite direction. That is, the first three main flow axes are angularly offset from one another in a clockwise direction and the fourth main flow axis is arranged at an angle counterclockwise with respect to the third main flow axis. The first three main flow axes describe a curved section. A curved section is understood to be a line section that describes a 30° to 120° curve in one plane. As already mentioned, the effect of the fourth valve loop can be increased by arranging it offset on the secondary air line.

In one embodiment it is provided that on the inside of the arcuate section arranged fourth diode valve loop is arranged on a curved section, wherein a course of the curved section is curved in the opposite direction to a course of the curved section.

In one embodiment, the valve loops are arranged in one plane. The secondary air line is usually made of a flexible material, in particular plastic. The valve loops lie in one plane when the secondary air line lies on one surface. In an installation position ready for operation, the secondary air line can be placed around components such as wheel housings and the like and be curved simply because an outlet connection of the secondary air pump is offset from an inlet connection of the exhaust gas tract.

In one application of the secondary air line, it is provided that the section into which the secondary air line opens is arranged upstream of a turbocharger, viewed in the direction of flow of exhaust gas from the internal combustion engine. Having the secondary air duct open into the exhaust tract upstream of the turbocharger potentially increases the amount of energy (heat and momentum) introduced into the turbocharger since the secondary air duct with diode valve loops has less of a tendency to absorb kinetic energy in the exhaust gas than a secondary air duct without diode valve loops. Accordingly, the amount of energy that can be absorbed at the turbine and delivered to a compressor increases.

The exhaust tract connects an outlet of an internal combustion engine to the environment in a fluid-conducting manner. Valves, bypasses, coolers, oxidation catalytic converters, turbines, 3-way catalytic converters, waste gates, SCR catalytic converters, EGR components and the like can be arranged in the exhaust gas tract. The internal combustion engine can be an Otto engine, in which additional fuel is injected during the warm-up phase, with a stoichiometric ratio being produced at the 3-way catalytic converter by blowing secondary air into the exhaust tract.

Brief description of the characters

The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. Show it:

1 : shows a schematic of a level of a section of an exhaust tract into which a secondary air line with valve loops opens; Fig. 2: Schematic representation of a level of a section of an exhaust tract into which a secondary air line with valve loops opens, with a secondary air pump which directs a gas, in particular air from the environment, into the exhaust tract through the secondary air line, with downstream from a position at which the secondary air line opens into the exhaust tract, a catalytic converter is arranged;

Fig. 3: Schematic representation of a level of a section of an exhaust tract into which a secondary air line with valve loops opens, with a secondary air pump that directs a gas, usually air from the environment, into the exhaust tract through the secondary air line, with downstream from a position at which the secondary air line opens into the exhaust tract, a turbine of an exhaust gas turbocharger is arranged; and

4: A comparison of a torque curve of an internal combustion engine with a secondary air line with diode valve loops and without diode valve loops.

The following description is merely illustrative in nature. For purposes of clarity, the same reference numbers will be used throughout the drawings to designate similar elements.

FIG. 1 shows a partially schematic secondary air line 10 for a section 13 of an exhaust tract 17 of an internal combustion engine, not shown in FIG. A main line 14 is provided with a first, second and third main flow axis 151, 152, 153 and three diode valve loops 16, which have an inlet 11 and an outlet 12 inclined by an outlet angle W12. The main line 14 can have a round cross section Q14 with Openings where the valve loops 16 are arranged. A cross section Q16 of the valve loops preferably corresponds to at least 90% of the cross section Q14 of the main line 14.

The main flow axes 151, 152, 153 intersect at each inlet 11. The inlet 11 extends in the direction of the main flow axes 151, 152, 153, 154 continued. The inlet 11 and the outlet 12 are fluidly connected to one another within the diode valve loop 16 . A fluid flowing through the valve loops is deflected around a curve of approximately 180°. Here, the fluid experiences a loss of momentum. Therefore, a flow resistance from the exhaust tract 17 to the secondary air pump 23 (see FIG. 2) is greater than in the opposite direction.

As stated, three diode valve loops 16 are provided in the first exemplary embodiment, which can be combined with the second and third exemplary embodiments. This are arranged on an arch section 22 . As a result, exhaust gas that flows from the exhaust tract 17 into the secondary air line 10 is faced with a greater flow resistance than with a straight main line, the exhaust gas is pushed into the valve loops 16 according to its mass inertia and the reversal of direction around the curve is associated with a loss of momentum. At each valve loop 16, the secondary air line 10 describes a curve around a shallow angle of between 10° and 40°.

Figure 2 shows a partially schematic second embodiment of a secondary air line 10 for a section 13 of an exhaust tract of an internal combustion engine 19. Also provided in the second embodiment is a main line 14 with a main flow axis 15 and at least one diode valve loop 16, which has an inlet 11 and a Outflow 12 which is inclined at an exit angle W12. The inflow 11 and the outflow 12 are fluidly connected to one another within the diode valve loop 16. The inlet 11 is branched off from the main line 14 in a fluid-conducting manner and the outlet 12 opens back into the main line 14 in a fluid-conducting manner.

As also described in connection with FIG. 1, three valve loops 16 are provided on the outside of the curved section in the exemplary embodiment shown in FIG. Furthermore, a further valve loop 161 is provided opposite. This is arranged on the opposite side of the main line 14 . By way of example, a catalytic converter 27 is arranged downstream of the section of the exhaust gas tract 17 .

In the exemplary embodiment shown in FIG. 3, what was said in connection with FIGS. 1 applies. Where applicable, specifically in relation to the fourth valve loop 161, what was said in connection with FIG. 2 also applies. Thus, in the third embodiment, three valve loops 16 are provided on the arcuate portion 22 on the outer circumference of the arcuate portion 22 and one valve loop 161 is provided on the inside of the arcuate portion 22. A catalytic converter, not shown, may be arranged downstream of the turbocharger 20 in the third embodiment.

The secondary air line 10 opens in the direction of flow 18 of exhaust gas from the internal combustion engine 19 upstream of a turbocharger 20 into the exhaust tract 17.

The main line 14 is the part of the secondary air line 10 that provides a fluid-conducting connection between the secondary air pump 23 and the exhaust tract 17 . Air flows with a low flow resistance from the secondary air pump to the exhaust tract 17 and with a higher flow resistance from the exhaust tract 17 to the secondary air pump 23. If no air is conveyed by the secondary air pump 23, not much can Exhaust gas get into the secondary air line 10, since the flow resistance is higher in this direction. In addition, vibrations in the secondary air line 10 are rapidly reduced since the increased flow resistance has a damping effect. As a result, a quantity of heat is also obtained in the exhaust tract 17, so that the energy that can be converted into charge pressure in the turbocharger 20 is correspondingly higher.

Furthermore, it is shown that the diode valve loop 161 arranged on the inside 24 of the arcuate section 22 is arranged on a curve section 25 , the curve section 25 running in the opposite direction to the curve section 22 . The valve loops 16 are arranged in a plane 26 in the exemplary embodiment shown, but there may be deviations from this in the operational installation position due to the installation space.

FIG. 4 shows a comparative dynamic curve of a torque over a time t as a step response of an internal combustion engine to a sudden setpoint increase. A curve 162 was measured in an internal combustion engine with diode valve loops according to FIGS. Another curve 163 was recorded on an internal combustion engine without diode valve loops. It can be seen that after some time the torque of the internal combustion engine with diode valve loops corresponding to curve 162 is significantly higher than the torque of the internal combustion engine without diode valve loops.

Although at least one exemplary embodiment has been presented in the foregoing description as well as the description of the figures, it should be recognized that a large number of variations exist. Furthermore, it should be appreciated that the embodiment(s) are only examples and are not intended to limit the scope, applicability, or precise configuration in any way. Rather, the description and description of the figures provide useful guidance for those skilled in the art for implementing at least one embodiment, it being understood that various changes in form and function of the described features may be made without departing from the scope of the claims and their equivalents . Reference list:

10 secondary air line

11 inflow

12 expiration

13 section

14 main line

151 main flow axis

152 main flow axis

153 main flow axis

154 main flow axis

16 valve loop

17 exhaust tract

19 internal combustion engine

20 turbocharger

21 outside

22 arc section

23 secondary air pump

24 inside

25 curve section

26 level

27 catalyst

161 valve loop

162 history

163 history Q14 cross section

Q16 cross section t time

M internal combustion engine

W12 angle

W151 angle

W152 angle

W153 angle

Claims

patent claims

1. Secondary air line (10) for a section (13) of an exhaust tract (17) of an internal combustion engine (19), having a main line (14) with main flow axes (151, 152, 153, 154) arranged at an angle to one another and with diode valve loops (16) , which have an inlet (11) which extends fluidly from the main line (14) and an outlet (12) which is inclined relative to the main flow axes (151, 152, 153, 154) by an exit angle (W12) and which is fluidly connected to the The main line (14) is connected, the inlet (11) and the outlet (12) within the diode valve loops (16, 161) being fluidly connected to one another.

2. Secondary air line (10) according to claim 1, wherein a fluid-conducting extension of the inlet (11) of the valve loop (16, 161) along the main flow axes (151, 152, 153, 154) is continued.

3. Secondary air line according to claim 1 and/or 2, wherein a cross section (Q16) of the valve loops (16, 161) is at least 90% as large, in particular the same size as a cross section (Q14) of the main line (14).

4. Secondary air line (10) according to one or more of the preceding claims, wherein a maximum of three diode valve loops (16) are arranged in a secondary air line (10).

5. Secondary air line (10) according to one or more of the preceding claims, wherein a maximum of four diode valve loops (16, 161) are arranged in a secondary air line (10).

6. Secondary air line (10) according to one or more of the preceding claims, wherein three diode valve loops (16) on an outer side (21) of a curved section (22) which the secondary air line (10) has between a secondary air pump (23) and the exhaust tract (17 ) describes, are arranged and wherein a fourth diode valve loop (161) is arranged on an inner side (24) of the arcuate section (22).

7. Secondary air line (10) according to claim 6, wherein the fourth diode valve loop (161) arranged on the inside (24) of the curved section (22) is arranged on a curve section (25), with a curve of the curve section (25) being opposite to a Course of the arcuate section (22) is curved.

8. secondary air line (10) according to one or more of the preceding claims, wherein the valve loops (16) are arranged in one plane (26).

9. Exhaust system of an internal combustion engine (19) for a motor vehicle, having a secondary air line (10) according to one of claims 1 to 8.

10. Secondary air line (10) according to one or more of the preceding claims, wherein the section (13) into which the secondary air line (10) opens, viewed in the flow direction (18) of exhaust gas from the internal combustion engine (19) upstream of a turbocharger ( 20) is arranged.