Apparatus and system for heating an exhaust stream of an internal combustion engine

Abstract

This utility model relates to a device for heating the exhaust gas flow (A) of an internal combustion engine, comprising: a pipe (1) that guides the exhaust gas flow (A) and has a pipe axis (Ra); a pipe joint (2) connected to the pipe (1) at an acute angle α, the pipe joint (2) having a pipe joint sleeve (2.1) arranged around a central axis (Ms), wherein the pipe (1) and the pipe joint (2) together form a channel (K) for the exhaust gas flow (A), and a burner (3) is provided on the pipe joint (2). To avoid local overheating caused by the burner (3), a combustion chamber (3.1) for the burner (3) is arranged at the end face inside the pipe joint (2), and a gap (5) for guiding the exhaust gas flow (A) is formed between the combustion chamber (3.1) and the pipe joint sleeve (2.1) of the pipe joint (2) around the circumferential direction of the combustion chamber (3.1).

Description

Technical Field

[0001] This utility model relates to a device for heating exhaust gas from an internal combustion engine, comprising: a pipe for conveying exhaust gas, the pipe having a pipe axis; and a pipe joint laterally connected to the pipe at a certain angle, the pipe joint having an outer pipe joint sleeve arranged around a central axis, wherein the pipe and the pipe joint together form a channel for exhaust gas flow, and a burner is disposed on the pipe joint. Unlike an intake pipe or exhaust pipe, the pipe joint typically has only one open end and is not used for conveying or discharging exhaust gas from the internal combustion engine. The burner is arranged at the closed end of the pipe joint. Background Technology

[0002] Patent document DE19720381A1 describes a burner having a combustion chamber connected to a passive fitting for an exhaust pipe. A catalyst is arranged between the combustion chamber and the fitting. According to patent document US5,339,630A1, the combustion chamber is arranged in a housing for accommodating the catalyst, and the burner is fixedly connected to the front end of the housing. An intake pipe for exhaust gases is connected to the housing at an acute angle. Utility Model Content

[0003] The purpose of this invention is to design and arrange a device for heating exhaust gas, so as to achieve the optimal distribution of heat in the exhaust gas flow while avoiding local overheating.

[0004] According to this invention, this objective is achieved by: a combustion chamber for a burner is arranged inside the pipe joint, and a gap for guiding exhaust gas flow is formed between the combustion chamber and the pipe joint sheath along the circumferential direction surrounding the combustion chamber. Preferably, the combustion chamber is arranged at the front end of the pipe joint. Particularly preferably, the combustion chamber is arranged at the closed end of the pipe joint.

[0005] This gap allows the exhaust gas, which is cooler than the combustion gases, to flow around the combustion chamber, achieving a uniform distribution of cooled exhaust gas and simultaneously cooling the pipe fitting sleeve. At the same time, the exhaust gas flow also cools the combustion chamber. The gap preferably extends along the entire length of the combustion chamber (i.e., the length along the central axis of the pipe fitting). According to different embodiments, this gap extends at least 80% of the length of the combustion chamber. The exhaust gas flow forms an exhaust gas cooling sleeve around the combustion chamber. The inner end of the pipe fitting refers to the end where the opening of the pipe fitting is closed along its central axis. An end cap or receiving seat is arranged at the opening of the pipe fitting, and the combustion chamber is fixedly connected to the end cap or receiving seat inside the channel. Other components of the burner (e.g., delivery lines, nozzles, intake pipes, etc.) are also fixedly connected to the end cap or receiving seat outside the channel. The shape of the pipe fitting sleeve relative to the central axis can be cylindrical, conical, or other rotationally symmetrical with respect to the central axis.

[0006] Regarding the geometry of the gap, it is advantageous that the combustion chamber is configured as a shell arranged coaxially with the pipe fitting. Depending on the different shapes of the combustion chamber and the pipe fitting sheath, their coaxial arrangement relative to the central axis can create different flows within the gap. The width of the gap along the central axis can be a constant or a variable. A constant gap width is particularly easy to achieve when both the pipe fitting and the combustion chamber have rotationally symmetrical geometries relative to the central axis and are similar in shape.

[0007] Considering the ease of modification of the device, it is preferable to design the pipeline as a single-wall structure and / or a single-piece structure. Unlike air-gap isolated pipelines, the local overheating problem of single-wall pipelines is more critical; therefore, according to this invention, exhaust gas is used for cooling.

[0008] For flow geometry, it is advantageous that the angle α between the central axis of the fitting and the pipe axis is acute, and preferably between 30° and 90°, or between 30° and 60°, or between 30° and 45°. The sharper or smaller the angle, the more parallel the gap between the combustion chamber and the fitting extends along the main flow direction of the exhaust gas through the pipe. When the angle is less than 45°, the exhaust gas can flow through almost the entire gap region located downstream of the combustion chamber (along the flow direction).

[0009] To improve flow around the combustion chamber, it may be advantageous to include a deflecting element in the channel and / or duct for deflecting the exhaust gas flow. This deflecting element causes the exhaust gas flow to be deflected, at least partially, from a flow direction extending parallel to the duct axis toward the combustion chamber by at least 15° or between 15° and 60° relative to the duct axis. The deflection angle depends on various factors, such as the incoming flow angle of the deflecting element, the exhaust gas mass flow rate, and the position of the deflecting element in the duct. The deflecting element deflects the exhaust gas flow from a flow direction along the duct axis to a direction approximately perpendicular to the central axis of the duct fitting. Therefore, the exhaust gas flow direction is also approximately perpendicular to the direction of extension of the combustion chamber in the duct fitting. The combustion chamber has a substantially cylindrical outer surface arranged coaxially with the central axis of the duct fitting, a structure that allows the exhaust gas flow perpendicularly impacting the combustion chamber to flow around the combustion chamber into the entire gap between the combustion chamber and the duct fitting.

[0010] Advantageously, the deflector element is constructed as a raised structure and arranged inside the pipe sheath. This raised structure is formed by deforming the pipe sheath or arranged and / or attached to the inside of the pipe sheath as a separate component. Viewed from the flow direction, the cross-section of the raised structure is arc-shaped, with its corresponding ends smoothly connecting to the internal geometry of the pipe. The maximum point of the raised structure is located opposite the combustion chamber along the circumferential direction around the pipe axis. This raised structure deflects most of the exhaust gas flow towards the pipe axis.

[0011] As an alternative to the raised structure, it is advantageous to construct the deflecting element as a geometry of one or more baffles arranged in the channel and attached to the inside of the pipe sheath or the combustion chamber as a separate component. For example, such a baffle can be inserted and installed in the pipe together with the combustion chamber. Using such a baffle eliminates the need for pipe deformation. The baffle can be installed in any conventional pipe with fittings in a separate assembly step, or simultaneously with the assembly of the combustion chamber.

[0012] Optimal exhaust gas distribution can be achieved when the deflector element is positioned at a location that minimizes the flow cross-section of the passage relative to the duct axis and opposite the combustion chamber. Within the combustion chamber region, the exhaust gas can diffuse away from the deflector element toward the combustion chamber. If the deflector element is positioned too close to the upstream end of the duct (along the airflow direction), the exhaust gas flow cross-section will be insufficient to meet the requirements.

[0013] To optimize exhaust gas flow around the combustion chamber, it is advantageous for the gap width to vary along the circumference of the combustion chamber, and / or for the minimum gap width to be 1 / 12 to 1 / 4 of the pipe diameter. When the geometry and position of the deflector element are optimal, the gap width can be reduced to a minimum while ensuring a sufficiently large exhaust gas mass flow rate around the combustion chamber, thereby preventing localized overheating. Attached Figure Description

[0014] Other advantages and details of this invention are set forth in the claims and description and are illustrated in the accompanying drawings. In the drawings:

[0015] Figure 1 A cross-sectional view of a device with a raised structure (German: Höcker) is shown;

[0016] Figure 2 A schematic diagram of the principle of the baffle plate attached to the combustion chamber is shown. Detailed Implementation

[0017] exist Figure 1The diagram shows a single-walled pipe 1 with a pipe axis Ra, in which exhaust gas A flows in through an inlet opening 1.2 and flows out through an exhaust opening 1.3. A pipe sleeve 1.1 forms part of a passage K for the exhaust gas A. A pipe fitting 2 is connected to the pipe 1, and the pipe fitting 2 has a central axis Ms that intersects the pipe axis Ra at an angle of approximately 40°. The pipe fitting 2 is defined radially relative to the central axis Ms by a surrounding pipe fitting sleeve 2.1.

[0018] At the end of the pipe connector 2 opposite to the pipe 1, a burner 3 is arranged on a receiving seat 2.2 designed as an end cap. The burner 3 has a combustion chamber 3.1 and an injector 3.2. The pipe connector 2 is not used to supply or discharge exhaust gas to or from the internal combustion engine. The pipe connector 2 is only used to supply combustion gases, and consequently also to supply exhaust gases from the burner 3, and is only used to accommodate the burner 3 with the combustion chamber 3.1 and the injector 3.2, while also supplying fuel. Fuel is supplied to the injector 3.2, while the exhaust gas from the burner 3 is fed into the exhaust gas flow of the internal combustion engine through the pipe connector 2. According to this invention, fuel is not supplied to the exhaust gas flow of the internal combustion engine through the pipe connector 2.

[0019] The combustion chamber 3.1 is completely disposed inside the pipe fitting and extends into the pipe fitting 2 from its end. The combustion chamber 3.1 has a cylindrical outer surface arranged substantially coaxially with the central axis Ms, which maintains a distance from the pipe fitting sleeve 2.1 along the entire circumference of the combustion chamber 3.1. This distance is radial relative to the central axis Ms. Due to this distance, a gap 5 with a width Bs is formed between the combustion chamber 3.1 and the pipe fitting sleeve 2.1. In this embodiment, the width Bs is approximately 1 / 6 of the diameter Dr of the pipe 1.

[0020] Due to the acute angle α formed when the pipe joint 2 connects to the pipe 1, the gap 5 between the combustion chamber 3.1 and the pipe joint 2 forms a corresponding angle α relative to the main flow direction of the exhaust gas flowing through the pipe 1. This geometry, in principle, ensures that exhaust gas flow A is formed within the gap 5.

[0021] To ensure a larger proportion of the exhaust gas flow A flows through gap 5, a raised deflector element 4 is provided opposite the combustion chamber 3.1. Deflector element 4 is formed by deforming the single-walled pipe 1 inwards towards the channel K. Deflector element 4 reduces the flow cross-section Dk of channel K in the region where combustion chamber 3.1 is located. Simultaneously, deflector element 4 deflects the exhaust gas flow A from a flow direction parallel to the pipe axis Ra toward combustion chamber 3.1. The exhaust gas flow A is partially deflected to such an extent that it impacts combustion chamber 3.1 approximately perpendicular to the central axis Ms of pipe joint 2. Due to the formed gap 5, the correspondingly deflected and perpendicularly impacting exhaust gas flow A flows in a circumferential direction around combustion chamber 3.1. In this way, the heat released by combustion chamber 3.1 is distributed around combustion chamber 3.1 and within exhaust gas flow A itself.

[0022] The sheath generated by the exhaust gas flow A around the combustion chamber 3.1 flows along the central axis M and extends beyond the combustion chamber 3.1, converging the flame downstream of the combustion chamber 3.1 and guiding it further into the duct 1. In this way, the inner wall of the duct 1 is isolated from the burner flame.

[0023] according to Figure 2 The deflecting element 4 is designed as a guide plate and is fixed to the combustion chamber 3.1 by the mounting element 4.1. This guide plate also has a guiding function, deflecting the exhaust gas flow A from a direction parallel to the pipe axis Ra to a direction perpendicular to the combustion chamber 3.1. With the help of the gap 5 formed, the exhaust gas flow A, after being deflected, vertically impacts the combustion chamber 3.1 and flows circumferentially around the combustion chamber 3.1. During this process, the exhaust gas flow carries away the heat dissipated by the combustion chamber 3.1.

Claims

1. An apparatus for heating exhaust gas (A) from an internal combustion engine, the apparatus comprising: a) A duct (1) for guiding the exhaust gas flow (A), the duct (1) having a duct axis (Ra) and a diameter (Dr); b) An outer pipe fitting sleeve (2.1) which surrounds the pipe fitting (2) connected to the pipe (1) at an angle α around the central axis (Ms). The pipe (1) and the pipe fitting (2) together form a channel (K) for the exhaust gas flow (A). c) Burner (3), said burner (3) is disposed on the pipe joint (2); d) A combustion chamber (3.1) for the burner (3), the combustion chamber (3.1) being arranged inside the pipe fitting (2), wherein a gap (5) for guiding the exhaust gas flow (A) is formed between the combustion chamber (3.1) and the pipe fitting sleeve (2.1) of the pipe fitting (2) along the circumferential direction surrounding the combustion chamber (3.1); and e) A deflecting element (4) disposed in the channel (K) and / or on the pipe (1) for deflecting the exhaust gas flow (A). The minimum value of the width (Bs) of the gap (5) is 1 / 12 to 1 / 4 of the diameter (Dr) of the pipe (1).

2. The apparatus of claim 1, wherein, The combustion chamber (3.1) is constructed as a housing arranged coaxially with the pipe joint (2).

3. The apparatus according to claim 1, wherein, The deflection element (4) enables the exhaust gas flow (A) to be deflected at least partially from the flow direction extending parallel to the duct axis (Ra) toward the combustion chamber (3.1) by at least 15° or between 15° and 60° relative to the duct axis (Ra).

4. The apparatus of claim 1, wherein, The deflection element (4) is formed as a raised structure arranged inside the pipe sleeve (1.1), wherein the raised structure is formed by deforming the pipe sleeve (1.1) of the pipe (1), or is constructed as a separate component and attached to the inside of the pipe sleeve (1.1).

5. The apparatus of claim 3 or 4, wherein, The deflection element (4) is configured as a geometry of one or more guide vanes arranged in the channel (K), and is attached as a separate component to the inside of the pipe sheath (1.1) or the combustion chamber (3.1).

6. The apparatus of claim 3 or 4, wherein, The deflection element (4) is positioned at a location (P) opposite the combustion chamber (3.1) relative to the pipe axis (Ra) to minimize the flow cross section (Dk) of the channel (K).

7. The apparatus of claim 3, wherein, The deflection element (4) is configured as a geometry of one or more guide vanes arranged in the channel (K) and is attached as a separate component to the inside of the pipe sheath (1.1) or the combustion chamber (3.1). The deflection element (4) is arranged at a position (P) opposite to the combustion chamber (3.1) relative to the pipe axis (Ra) to minimize the flow cross section (Dk) of the channel (K).

8. The apparatus of claim 1, wherein, The width (Bs) of the gap (5) varies along the circumference of the combustion chamber.

9. A system comprising the device according to any one of the preceding claims and an exhaust system or a portion thereof of a motor vehicle.

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