Exhaust system for an internal combustion engine

Abstract

Exhaust system for an internal combustion engine with at least one exhaust gas-carrying pipe (1) and a connection nozzle (3) arranged on the pipe (1) for applying exhaust gas pressure to a sensor (6) arranged near the pipe for dynamically measuring the pressure in the pipe (1), wherein the connection nozzle (3) is designed with a device for reducing the exposure of a component coupled to the sensor (6) to the exhaust gas pressure line to heat from the exhaust gas, characterized in that: - the device has a first connection section of the connection piece (3) and a second connection section of the connection piece (3); - the first connecting section extends away from the pipe (1) and in a direction upwards towards the pressure sensor (6); - the first connecting nozzle section has a transition area (10) at its upper end area that connects the first connecting nozzle section to the second connecting nozzle section; - the second connecting section extends from the transition area (10) towards the pipeline (1) and has a shorter longitudinal extent than the first connecting section; - the second connection section has a larger transverse extent than the first connection section and is arranged coaxially or at an angle to the first connection section and an air gap is formed between the connection sections for thermal insulation of the second connection section, to the outer circumference of which an elastic connecting hose (4) is attached, which connects the sensor (6) to the second connection section in a pressure-tight manner.

Description

[0001] The present invention relates to an exhaust system for an internal combustion engine with at least one exhaust gas-carrying pipeline and a connection nozzle arranged on the pipeline for applying exhaust gas pressure to a sensor arranged near the pipeline for dynamic measurement of the pressure in the pipeline.

[0002] Exhaust systems of combustion engines can be equipped with sensors that, for example, measure the composition of the exhaust gases. A sensor may also be included to measure the pressure upstream of a particulate filter integrated into the exhaust system. If the particulate filter becomes too loaded with soot particles, a regeneration process is initiated, depending on the measured pressure. This process burns off the soot particles in a controlled manner to reduce the back pressure in the exhaust system back to a predetermined value.

[0003] To measure the pressure, a pressure sensor positioned at a distance from an exhaust system pipe can be used. This sensor is mounted on the body of a vehicle equipped with an internal combustion engine. For static pressure measurement, the pressure upstream of the particulate filter is transmitted to the pressure sensor via a connecting hose attached to a fitting on the pipe. The connecting hose is elastic and can compensate for operational changes in the length and shape of the pipe.

[0004] In this case, a cost-effective component can be used as the connecting hose. This component is decoupled from the high temperatures of the pipeline by using a metallic connector with a large longitudinal extension. This reduces the heat from the pipeline, which is transferred to the connecting hose via conduction through the connector, due to cooling of the connector by airflow and heat radiation along its length. Static pressure measurement can therefore utilize long pressure lines to mitigate the problem of heat exposure of the flexible connecting hose.

[0005] Long pressure lines are a disadvantage in dynamic pressure measurements, where dynamically changing pressures are measured at short intervals, because they can introduce transit-time errors. Furthermore, if a long, flexible connecting hose is used to transmit the pressure between the point where the pressure is taken and the point where it is measured—in an exhaust system, this would be a branch of the pipeline and a pressure sensor located at a distance from it—the pressure measurement signal can be distorted by movements of the connecting hose.

[0006] Dynamic pressure measurement is used, for example, in an Active Noise Control system, in which noises disturbing to the user of a vehicle are dampened by actively bombarding the vehicle interior with sound waves that are phase-shifted relative to the disturbing noises, which are intended to cancel out the sound waves perceived by the user as disturbing noises.

[0007] For this purpose, microphones are placed inside the vehicle to detect background noise and supply the control electronics with input signals.

[0008] An exhaust system can also include an actuator for applying out-of-phase sound waves to the combustion noise of the internal combustion engine. These waves can be used to cancel or dampen the engine's noise emissions. For this purpose, the sound waves to be dampened must be measured and fed into a control loop. This highly dynamic control loop requires pressure input signals to provide phase-shifted sound waves to the actuator. A long pressure measurement line is unsuitable for this purpose, as the resulting propagation delays would negatively impact the control loop's response speed.

[0009] If dynamic pressure measurements of the pressure prevailing in an exhaust system are to be carried out, a suitable pressure sensor must be applied close to the exhaust system pipeline to avoid the signal distortions described above, largely avoiding a body-fixed connection of the sensor.

[0010] For this purpose, the pressure sensor can be attached, for example, to a silencer or actuator of the exhaust system, or to an actuator already present in the exhaust system. Since the exhaust system experiences changes in length due to temperature, the pressure line from the pipe to the pressure sensor must be designed to be flexible.

[0011] The limited installation space available in the underbody area of ​​a vehicle for integrating the exhaust system with a pressure sensor arranged for dynamic pressure measurement means that a metallic connection fitting for receiving an elastic pressure line can only be very short, so that it can hardly dissipate heat between its branch on the pipeline and the point of connection of the elastic pressure line on the connection fitting.

[0012] As a result, the thermal stress on the elastic pressure line at the point of its connection to the fitting is very high and quickly exceeds the specification-related permissible limits for an elastic pressure line, which may be a silicone elastomer hose, especially during high-temperature driving, i.e., driving the vehicle with high engine load.

[0013] Based on DE 198 54 095 A1, an exhaust system with an exhaust pipe for directing the exhaust gas to a catalyst has become known, which quickly reaches its start-up temperature, since an air gap insulation of the exhaust pipe ensures that the exhaust gas releases little heat to the environment on its way to the catalyst.

[0014] Based on DE 10 2011 086 798 A1, a metering module with air gap insulation has become known, which is intended for introducing a reducing agent into the exhaust tract of an internal combustion engine and the air gap insulation serves to cool the metering module by convection.

[0015] Based on EP 2 607 640 A1, which originates from the applicant, an actuator arrangement for an active exhaust system has become known, which in Fig. Figure 7 shows a cooling channel arranged around a sensor for cooling the sensor.

[0016] DE 201 19 312 U1 discloses a pressure sensor. DE 10 2006 053 804 A1 discloses an exhaust aftertreatment device for treating exhaust gases in the exhaust system of an internal combustion engine. DE 101 57 402 A1 discloses a pressure sensor. DE 39 42 298 A1 discloses a device for measuring a first operating characteristic of an internal combustion engine by means of a sensor located in the exhaust system. DE 198 56 366 C1 discloses a device for treating exhaust gases from an internal combustion engine operating with excess air.

[0017] Based on this, the present invention aims to provide an exhaust system for an internal combustion engine that enables a dynamic measurement of the pressure prevailing in the exhaust system.

[0018] The invention, in order to solve this problem, comprises the features specified in claim 1. Advantageous embodiments thereof are described in the further claims.

[0019] The invention provides an exhaust system for an internal combustion engine with at least one exhaust gas-carrying pipeline and a connection nozzle arranged on the pipeline for applying exhaust gas pressure to a sensor arranged near the pipeline for dynamically measuring the pressure in the pipeline, wherein the connection nozzle is equipped with a device for reducing the exposure of a component coupled to the sensor for the exhaust gas pressure line to heat from the exhaust gas.

[0020] In other words, the invention provides an exhaust system with at least a single-flow pipe, the cross-section of which can be arbitrarily designed, and a connection nozzle arranged on the pipe, the cross-section of which can also be arbitrarily designed, and through which the exhaust pressure prevailing in the exhaust system can propagate towards the pressure measuring sensor arranged near the pipe, in order to enable a dynamic measurement of the exhaust pressure prevailing in the pipe.

[0021] The device comprises a first connection section and a second connection section. The first connection section extends away from the pipeline and upwards towards the pressure sensor. At its upper end, the first connection section has a transition section that connects it to the second connection section. The second connection section extends from this transition section towards the pipeline and is shorter than the first connection section.The second connection section has a larger transverse extent than the first connection section and is arranged coaxially or at an angle to the first connection section, and an air gap is formed between the connection sections for thermal insulation of the second connection section, to the outer circumference of which an elastic connecting hose is attached, which connects the sensor to the second connection section in a pressure-tight manner.

[0022] The connection fitting is connected to the pressure sensor via a component in the form of an elastic connecting hose, which is connected to the pressure sensor either directly or via an intermediate fluid line. The device provided on the connection fitting, designed to reduce the heat exposure of the component to the exhaust gas, cools the connection fitting itself, not the sensor as in the document described above. This ensures that the elastic connecting hose, as an example, is not subjected to a temperature profile exceeding its specifications at its point of attachment to the connection fitting.

[0023] The device is designed to have a first connecting section extending away from the pipeline and a second connecting section extending towards the pipeline. This creates a configuration where the connecting section has two parts: the first part, viewed from the point where the connecting section branches off from the pipeline, extends away from the pipeline, and the second part extends back towards the pipeline.

[0024] Such a configuration allows the formation of a connection fitting corresponding to an elongated connection fitting in terms of longitudinal extension, without requiring the installation space needed to accommodate an elongated connection fitting.

[0025] The second section is designed to have a shorter length than the first, meaning it does not extend back to the pipeline. This type of connection allows heat to dissipate along its length, thus providing a location for attaching a flexible connecting hose in the second section. This hose experiences a heat load at this point that is largely equivalent to that at the end of a known elongated connection, but without requiring the same amount of space.

[0026] The second section has a larger transverse extent than the first connection section and is arranged coaxially or at an angle to the first connection section, with an air gap formed between the two sections. This air gap ensures thermal insulation between the two connection sections, allowing the second connection section, which has larger external dimensions and surrounds the first connection section at least along part of its longitudinal extent, to maintain a significantly lower temperature than the first connection section. The second section can surround the first section coaxially or at an angle to it, for example, forming an expanding pipe section that surrounds the first connection section.

[0027] If the elastic connecting hose is attached to the second connection section, it is exposed to a significantly lower temperature load than would be the case if it were attached to the end of the first connection section. Furthermore, when the vehicle is driven with the exhaust system according to the invention, turbulence occurs in the air gap between the two connection sections, promoting heat dissipation in the area of ​​the air gap and thus actively cooling the second connection section by the air gap.

[0028] The transition area between the two connection nozzle sections can be designed as a ring in a top view, so that the first connection nozzle section transitions radially inside into the transition area and the transition area transitions radially outside into the second connection nozzle section.

[0029] According to a further development of the invention, the second connection section is designed on its outer circumference to accommodate the aforementioned elastic connecting element, for example, an elastic connecting hose, which connects the sensor to the second connection section in a pressure-tight manner. For this purpose, the second connection section can have at least one radial extension over which the elastic connecting hose is pushed, causing it to expand radially. This allows the pressure-tight connection between the connecting hose and the connection section to be achieved without the need for additional fastening means.

[0030] The first and / or second connection section is preferably made of a metallic material, for example the same material as the exhaust system piping, so that the second connection section receives appropriate cooling via the turbulence in the air gap generated when the vehicle is driven.

[0031] In addition to the previously described possibility of air gap insulation and the correspondingly designed connection sections, a further development of the invention provides that the device also includes a finned tube which is arranged in the area between a branch of the pipeline and the pressure sensor. The finned tube has a large surface area on its outer circumference relative to its longitudinal extent, so that a location distal to the branch on the finned tube for attaching the sensor directly to the finned tube or an elastic connecting hose connected to the sensor has a significantly lower temperature level than the branch itself. Thus, in the case of a direct sensor placement on the finned tube, the sensor inlet, and in the case of a connecting hose on the finned tube, the connecting hose itself, experience a significantly reduced heat load.

[0032] In general, according to the invention, the connecting nozzle and / or a connection point formed on the lamellar tube for the elastic connecting hose has a closed profile and is in particular circular in shape.

[0033] According to a further development of the invention, the connection fitting on the pipeline is also arranged in such a way that condensate flows from the connection fitting into the pipeline. Such a configuration has the advantage that condensate present in the exhaust system, which enters the connection fitting, flows back into the pipeline, and that at low temperatures, ice cannot form and clog the connection fitting, the finned tube, the connecting hose, or the pressure sensor inlet.

[0034] According to a further development of the invention, the connecting piece can also be chamfered in the area of ​​the end section of the second connecting piece section, wherein the chamfered end section has a shorter area in the longitudinal direction of a vehicle equipped with the exhaust system located at the front and thus intensive air turbulence occurs in the area of ​​the air gap between the two connecting piece sections when the vehicle is driving, thereby further improving the cooling of the second connecting piece section.

[0035] The invention will be explained in more detail below with reference to the drawing. This shows: Fig. 1 a schematic representation of a known pipe-adjacent arrangement of a pressure measuring sensor; Fig. 2 a schematic representation similar Fig. 1, which, however, shows an embodiment according to the invention; Fig. 3 a representation similar Fig. 2, which shows the connection nozzle with the connecting hose separated from it; Fig. 4 a representation similar Fig. 3, which shows a second embodiment according to the invention; Fig. 5 a schematic representation of a third embodiment according to the invention; and Fig. 6 a representation similar Fig. 5, which shows a fourth embodiment.

[0036] Fig. Figure 1 of the drawing shows a schematic representation of a known exhaust system with a pressure sensor arranged close to the pipeline for the dynamic measurement of the pressure prevailing in the pipeline.

[0037] A silencer or actuator 2 is arranged on a pipe 1 in which the exhaust gas flows in the direction of the arrow. This actuator serves to reduce the noise emission of an internal combustion engine (not shown in detail). The silencer or actuator 2 has a housing that can be used to mount the pressure sensor described below. The exhaust system can also include the aforementioned actuator, which is used to dampen the noise emissions of the internal combustion engine and also has a housing to which the pressure sensor can be attached.

[0038] Pipeline 1 has a connection fitting 3 to which an elastic connecting hose 4 is attached and secured by a fastening element, such as a spring washer or a hose clamp. At the other end of the connecting hose 4, another fastening element 5 is provided, which seals the connecting hose 4 pressure-tight to the inlet of a pressure sensor 6.

[0039] The pressure sensor 6 can be detachably attached to the housing of the silencer or actuator 2 by means of a mounting component 7. In this way, a pipe-close arrangement of the pressure sensor 6 can be realized, but with significant disadvantages that render such a known arrangement unsuitable for practical use.

[0040] At the point where the connecting hose 4 is attached to the connection nozzle 3, a temperature T1 can be measured in the known arrangement that reaches values ​​of up to 320 °C during actual operation of the internal combustion engine. Such temperature values ​​are far beyond the specification range of connecting hoses suitable for series production, which are typically made of silicone elastomer and are usually approved for upper temperature ranges of 200 °C.

[0041] At the other end of the connection nozzle 3, temperatures T2 of approximately 180 °C are present; the coverage area between the location where the temperature T1 is measured and the location where the temperature T2 is measured is required for the secure and pressure-tight connection of the connecting hose 4 to the connection nozzle 4, and therefore cannot be shortened.

[0042] Fig. Figure 2 of the drawing shows an embodiment of an exhaust system according to the invention. A silencer or actuator 2 is arranged on the pipe 1, from which a connecting piece 3 branches off, to which a connecting hose 4 is arranged, which connects the connecting piece 3 in a pressure-tight manner to an inlet of a pressure measuring sensor 6, which is fixed to the silencer or actuator 2 by means of a retaining component 7.

[0043] For further explanation of this embodiment, see Fig. Reference is made to Figure 3 of the drawing. This shows the connection fitting 3 with a first connection fitting section and a second connection fitting section. The first connection fitting section extends largely vertically from the pipeline 1 upwards towards the pressure measuring sensor 6 and has a transition area 10 at its upper end, which connects the first connection fitting section to the second connection fitting section.

[0044] The second connecting section extends from the transition area 10 towards the pipeline 1, but has a shorter longitudinal extent and larger outer dimensions than the first connecting section. In the illustrated embodiment, both connecting sections are circular tubes; therefore, the second connecting section has a larger outer diameter than the first.

[0045] In this way, an air gap 11 is formed radially outside the first connection nozzle section and radially inside the second connection nozzle section, which serves for the thermal insulation of the second connection nozzle section, to which the in Fig. The connecting hose 4 shown in the drawing can be attached.

[0046] Temperature measurements under otherwise unchanged temperature measurement conditions at continuous full engine load have shown that the contact area between the connection nozzle 3 and the connecting hose 4, where the highest temperatures prevail, is the transition area 10 between the two connection nozzle sections, where maximum temperatures of 160 °C occur. These temperatures can be accommodated with a cost-effective silicone elastomer hose.

[0047] Fig. Figure 4 shows a schematic representation of a second embodiment according to the invention, which differs from the one in Figure 4. Fig. 2 and Fig. The embodiment shown in Figure 3 differs in that the end section 12 near the pipe is chamfered. This configuration results in strong turbulence in the air gap 11 when the vehicle (not shown) equipped with the exhaust system according to the invention is driven in the opposite direction to the direction of the exhaust flow indicated by the arrow in the pipe 1. This turbulence further reduces the measured temperature T2. In this way, the use of connecting hoses made of even more cost-effective materials is possible.

[0048] Fig. Figure 5 of the drawing shows a further embodiment of an exhaust system according to the present invention. In this embodiment, a finned tube 13 is connected to a short connecting piece 3, and the connecting hose 4 can be attached to the end section 14 of the finned tube opposite the connecting piece 3. The connecting hose 4 connects the pipeline 1 to the pressure sensor 6 (not shown in detail here) in a pressure-tight manner.

[0049] The lamellar tube 13 can be arranged on the underbody of the vehicle (not shown in detail) in such a way that it is cooled by the airflow prevailing in the area of ​​the underbody when the vehicle is in motion.

[0050] Finally, it shows Fig. 6 of the drawing shows a further embodiment, which differs from the one in Fig.The embodiment shown in section 5 of the drawing differs in that the pressure measuring sensor 6 can be fixed directly to the end section 14 of the finned tube 13 without the need for an intermediate connecting hose.

[0051] The invention enables the integration of a pressure sensor close to the exhaust system of a vehicle's internal combustion engine, without requiring significant installation space. By designing the exhaust system in such a way that the connection nozzle required for the pressure sensor is cooled, it is possible to manufacture a cost-effective, elastic connecting hose for a pressure-tight connection between the pipe and the pressure sensor, without having to resort to special materials that are too expensive for mass production and are suitable for high-temperature resistant applications.

[0052] The design of the connection fitting with two sections results in a long connection fitting without requiring the installation space needed for a conventional long connection fitting. By incorporating a finned tube into the exhaust system between the connection fitting and the pressure sensor, the heat load on the connecting hose located between the pressure sensor and the finned tube can be further reduced. Additionally, the finned tube also reduces the heat load on the pressure sensor itself.

[0053] With regard to features of the invention not explained in detail above, explicit reference is made to the claims and the drawing. Reference symbol list 1 pipeline 2 silencers, actuator 3 connection spigots 4 connecting hoses 5 Fastening element 6 pressure sensor 7 Mounting component 8 first connection section 9 second connection section 10 Transition area 11 Air gap space 12 Final section 13 lamellar tube 14 Final Section

Claims

[1] Exhaust system for an internal combustion engine with at least one exhaust gas-carrying pipe (1) and a connection nozzle (3) arranged on the pipe (1) for applying exhaust gas pressure to a sensor (6) arranged near the pipe for dynamically measuring the pressure in the pipe (1), wherein the connection nozzle (3) is designed with a device for reducing the exposure of a component coupled to the sensor (6) to heat from the exhaust gas to the connection nozzle connected to the exhaust gas pressure line, characterized by , that: - the device has a first connection section of the connection piece (3) and a second connection section of the connection piece (3); - the first connecting section extends away from the pipe (1) and in a direction upwards towards the pressure sensor (6); - the first connecting nozzle section has a transition area (10) at its upper end area that connects the first connecting nozzle section to the second connecting nozzle section; - the second connecting section extends from the transition area (10) towards the pipeline (1) and has a shorter longitudinal extent than the first connecting section; - the second connection section has a larger transverse extent than the first connection section and is arranged coaxially or at an angle to the first connection section and an air gap is formed between the connection sections for thermal insulation of the second connection section, to the outer circumference of which an elastic connecting hose (4) is attached, which connects the sensor (6) to the second connection section in a pressure-tight manner. [2] Exhaust system according to claim 1, characterized by, that in the transition area (10) between the two connecting nozzle sections (8, 9) a connecting section is arranged which is ring-shaped in a top view. [3] Exhaust system according to claim 1 or 2, characterized by , that the first (8) and / or second (9) connecting nozzle section is made of a metallic material. [4] Exhaust system according to one of the preceding claims, characterized by , that the connecting piece (3) has a closed profile in cross-section. [5] Exhaust system according to one of the preceding claims, characterized by , that the connection nozzle (3) on the pipeline (1) is arranged in such a way that condensate flows from the connection nozzle (3) into the pipeline (1). [6] Exhaust system according to one of the preceding claims, characterized by, that the connecting piece (3) has a chamfered end section (12), the shorter area of ​​which is located at the front in the longitudinal direction of a vehicle equipped with the exhaust system.

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