Heating device for exhaust system of internal combustion engine

Abstract

A heating device (6) for an exhaust system (1) of an internal combustion engine (2), the heating device (6) having a tubular body (12) with a combustion chamber (7) inside, a fuel injector (9) designed to inject fuel into the combustion chamber (7), at least one inlet opening (18) connectable to a fan (8) to receive an air flow directed to the combustion chamber (7), a feed channel (21) receiving air from the inlet opening (18), surrounding an end portion of the fuel injector (9) and ending with a nozzle (22) arranged around the injection tip of the fuel injector (9), and a spark plug (10) mounted through a side wall (16) of the tubular body (12). The feed channel (219) is delimited on the outside by an outer tubular body (24). The fuel injector (9) is configured to inject at least a portion of the fuel onto the outer tubular body (24) which has a through hole (33) through which the nozzle tip of the fuel injector (9) directly aims the electrodes (31, 32) of the spark plug (10) to emit fuel.

Description

[0001] Cross-references to related applications

[0002] This patent application claims priority to Italian patent application No. 102021000001880, filed on January 29, 2021, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This invention relates to a heating device for the exhaust system of an internal combustion engine. Background Technology

[0004] The exhaust system of an internal combustion engine includes an exhaust pipe along which at least one device for treating the exhaust gases from the engine is installed; specifically, a catalytic converter (oxidation catalytic converter or reduction catalytic converter) is always present, to which a particulate filter can be added. For it to function (i.e., for catalytic conversion to take place), the catalytic converter needs to operate at relatively high temperatures (modern catalytic converters even operate at temperatures approaching 800°C), because only after reaching the operating temperature will the chemical reactions that convert unburned hydrocarbons, nitrogen oxides, and carbon monoxide into carbon dioxide, water, and nitrogen occur.

[0005] During the cold start phase (i.e., when the internal combustion engine is restarted after being shut down for an extended period, allowing the different components of the engine to reach ambient temperature), the temperature of the catalytic converter remains significantly below its operating temperature for a relatively long time (even a few minutes during winter and while the engine is idling or running very slowly in urban conditions). Therefore, during the cold start phase, i.e., the time before the catalytic converter reaches its operating temperature, emissions are very high because the catalytic converter's purification effect is close to zero, or at least negligible.

[0006] To accelerate the attainment of the catalytic converter's operating temperature, patent documents EP0631039A1, WO2012139801A1, US8006487B2, US2011289906A1, EP0590699A1, and JP2005180371A1 suggest installing a heating device along the exhaust pipe. This heating device generates a (very) hot airflow by burning fuel, which flows through the catalytic converter. Specifically, the heating device includes a combustion chamber connected at its outlet to the exhaust pipe (immediately upstream of the catalytic converter) and at its inlet to a fan that generates an airflow through the combustion chamber; within the combustion chamber are also a fuel injector that injects fuel mixed with air, and a spark plug that periodically generates a spark to ignite the air-fuel mixture, thereby achieving combustion of heated air.

[0007] In known heating devices, fuel does not always burn completely under all operating conditions, and therefore unburned fuel may reach the exhaust pipe and burn within it (especially when a large amount of fuel is injected to generate a large amount of heat), resulting in localized, sudden, unexpected, and undesirable temperature increases. Summary of the Invention

[0008] The object of the present invention is to provide a heating device for the exhaust system of an internal combustion engine, which allows for complete combustion of fuel (i.e., does not introduce unburned fuel into the exhaust pipe), and is also simple and economical to manufacture.

[0009] According to the present invention, a heating device for an internal combustion engine exhaust system is provided, the heating device comprising:

[0010] A tubular body, the interior of which contains a combustion chamber;

[0011] A fuel injector, which is mounted through the bottom wall of a tubular body to inject fuel into the combustion chamber;

[0012] At least one inlet opening is provided, which can be connected to a fan to receive an airflow that is directed to the combustion chamber and mixed with fuel.

[0013] The feed passage receives air from the inlet opening, surrounds the end portion of the fuel injector, and terminates at a nozzle arranged around the injection tip of the fuel injector; and

[0014] A spark plug, which is mounted through the sidewall of a tubular body to trigger the combustion of an air-fuel mixture and has electrodes;

[0015] The feed channel is defined on the outside by an outer tubular body (with the inner surface of the feed channel) and on the inside by an inner tubular body that surrounds and contains the fuel injector.

[0016] The heating device is characterized by:

[0017] The fuel injector is configured to inject at least a portion of the fuel onto the outer tubular body; and

[0018] The outer tubular body has a through hole through which the nozzle tip of the fuel injector directly targets the spark plug electrode to release fuel.

[0019] The appended claims describe preferred embodiments of the invention and form part of the specification.

[0020] Brief description of the attached figures

[0021] The invention will now be described with reference to the accompanying drawings, which illustrate some non-limiting embodiments of the invention, wherein:

[0022] · Figure 1 This is a schematic partial view of an internal combustion engine exhaust system equipped with a heating device according to the present invention;

[0023] · Figure 2 yes Figure 1 A schematic longitudinal sectional view of the heating device, with components removed for clarity;

[0024] · Figure 3 yes Figure 2 A magnified view of the details;

[0025] · Figure 4 yes Figure 2 A magnified view showing different embodiments;

[0026] · Figure 5 and Figure 6 It is by Figure 1 Two schematic diagrams of alternative embodiments of fuel jets produced by the fuel injector of the heating device;

[0027] · Figure 7 yes Figure 1 Schematic diagram of the spark plug for the heating device;

[0028] · Figure 8 yes Figure 5 A schematic diagram of the spark plug electrode highlights the possible directions of the fuel jet injected by the fuel injector.

[0029] · Figure 9 and Figure 10 yes Figure 7 A schematic diagram of an alternative embodiment of the spark plug electrode highlights the possible direction of the fuel jet injected by the fuel injector; and

[0030] · Figure 11 According to further embodiments Figure 2 A magnified view of the details.

[0031] Preferred embodiments of the present invention

[0032] exist Figure 1 In the text, the number 1 represents the exhaust system of the internal combustion engine 2 as a whole.

[0033] The exhaust system 1 includes an exhaust pipe 3 that begins at the exhaust manifold of the internal combustion engine 2 and ends at a muffler 4, from which exhaust gases are released into the atmosphere. At least one device 5 for treating the exhaust gases from the internal combustion engine is installed along the exhaust pipe 3; specifically, a catalytic converter (oxidation catalytic converter or reduction catalytic converter) is always present, to which a particulate filter can be added. For it to function (i.e., for catalytic conversion to take place), the catalytic converter needs to operate at relatively high temperatures (modern catalytic converters even operate at temperatures approaching 800°C), because only after reaching the operating temperature will the chemical reactions that convert unburned hydrocarbons, nitrogen oxides, and carbon monoxide into carbon dioxide, water, and nitrogen occur.

[0034] In order to accelerate the heating of the processing unit 5, that is, to allow the processing unit 5 to reach its operating temperature more quickly, the exhaust system 1 includes a heating device 6, which generates a (very) hot airflow by burning fuel, which flows through the processing unit 5.

[0035] The heating device 6 includes a combustion chamber 7, which is connected at its outlet to an exhaust duct 3 (immediately upstream of the processing device 5) and at its inlet to a fan 8 (i.e., an air pump) that generates an airflow through the combustion chamber 7. The combustion chamber 7 also contains a fuel injector 9 that injects fuel mixed with air, and a spark plug 10 that periodically generates a spark to ignite the air-fuel mixture, thereby achieving combustion of heated air. The combustion chamber 7 of the heating device 6 terminates at an outlet duct 11, which leads to the exhaust duct 3 (immediately upstream of the processing device 5).

[0036] according to Figure 2 The heating device 6 includes a tubular body 12 having a longitudinal axis 13 (e.g., having a cylindrical shape and a circular or elliptical cross-section); the tubular body 12 is defined at both ends by two opposing bottom walls 14 and 15 and laterally by side walls 16 connecting the two bottom walls 14 and 15 to each other. The bottom wall 14 has a central perforation to accommodate a fuel injector 9, which is coaxially mounted to the tubular body 12 (i.e., coaxial with the longitudinal axis 13); in other words, the fuel injector 9 is mounted through the bottom wall 14 of the tubular body 12 to inject fuel into the combustion chamber 7.

[0037] Similarly, the bottom wall 15 has a central perforation for fitting onto the outlet pipe 11, which ends at the exhaust pipe 3; that is, the bottom wall 15 has an outlet opening 17 to expel hot air from the combustion chamber 7, and the outlet pipe 11 begins at the combustion chamber 7.

[0038] according to Figure 2 At least a portion of the inlet opening 18 is obtained through the tubular body 12, the inlet opening 18 being connected to the inlet pipe 19. Figure 1(As shown) is connected to fan 8 to receive airflow, which is directed to combustion chamber 7 and mixed with fuel injected by fuel injector 9. Preferably, air flows into inlet opening 18 in a tangentially oriented (relative to tubular body 12) airflow, that is, inlet duct 19 is tangentially oriented (relative to tubular body 12).

[0039] according to Figure 1 The illustrated possible, but non-limiting, embodiment includes a check valve 20 in the region of inlet opening 18, which allows air to flow only into combustion chamber 7 (i.e., into tubular body 12). Preferably, check valve 20 is passive (i.e., does not include an electric, hydraulic, or pneumatic actuator to generate motion), is pressure-controlled, and only opens when the pressure upstream of check valve 20 is higher than the pressure downstream of check valve 20. The function of check valve 20 is to prevent exhaust gas backflow when heating device 6 is not in use (i.e., when fan 8 is off) until it flows out of inlet opening 18, thus being released into the atmosphere without passing through treatment device 5. Alternatively, check valve 20 may be installed along outlet duct 11, for example, in the region of outlet opening 17; in this case, check valve 20 only allows air to flow from combustion chamber 7 (from tubular body 12) to exhaust duct 3, i.e., it prevents exhaust gas from flowing from exhaust duct 3 into combustion chamber 7 (into tubular body 12).

[0040] according to Figure 2 The heating device 6 includes a feed channel 21 that receives air from an inlet opening 18, surrounds the end portion of the fuel injector 9 and ends at a nozzle 22, which is arranged around the injection point of the fuel injector 9 (i.e. around the nozzle tip of the fuel injector 9 from which fuel flows out).

[0041] The spark plug 10 is installed through the side wall 16 of the tubular body 12 to trigger the combustion of the air-fuel mixture, which is obtained by mixing air and fuel. Air flows into the tubular body 12 from the inlet opening 18 and is introduced into the combustion chamber 7 by the nozzle 22 of the feed passage 21, while fuel is injected into the combustion chamber 7 by the fuel injector 9. In particular, the side wall 16 of the tubular body 12 has a through hole that is radially (i.e., perpendicular to the longitudinal axis 13) and internally accommodates (screwed into) the spark plug 10 (which is obviously radially oriented).

[0042] The heating device 6 includes a static mixer 23 (i.e., no moving parts) having an annular shape, arranged along the feed channel 21 and around the fuel injector 9 and configured to generate turbulence, particularly vortex motion, in the air flowing toward the nozzle 22.

[0043] According to the preferred but non-limiting embodiment shown in the accompanying drawings, downstream of the static mixer 23, the feed channel 21 has a gradually decreasing cross-sectional area to accommodate increases in air velocity. Specifically, downstream of the static mixer 23, the feed channel 21 has an initial portion with a constant cross-sectional area, an intermediate portion with a gradually decreasing cross-sectional area, and an end portion with a constant cross-sectional area up to the nozzle 22.

[0044] The feed channel 21 is defined on the outside by an outer tubular body 24 (at least partially conical) and on the inside by an inner tubular body 25 (at least partially conical), the inner tubular body 25 surrounding the fuel injector 9 and containing the fuel injector 9 (i.e., a container serving as the end part of the fuel injector 9) on the inside. That is, the feed channel 21 is defined between the inner tubular body 25 and the outer tubular body 24. Specifically, the two tubular bodies 24 and 25 alternate between conical portions (i.e., a converging shape with gradually decreasing dimensions) and cylindrical portions (i.e., a shape with constant dimensions); preferably, the end part of the inner tubular body 25 has a converging taper (i.e., its dimensions gradually decrease towards the nozzle 22), while the end part of the outer tubular body 24 has a cylindrical shape.

[0045] According to a preferred embodiment, air flows into the feed passage 21 in a tangentially oriented airflow to have vortex motion (which is subsequently enhanced by the action of the static mixer 23), which helps it mix with the fuel injected by the fuel injector 9; in other words, introducing combustion air into the combustion chamber 7 through a duct tangentially oriented to the combustion chamber 7 allows the combustion air flow to have circumferential motion (which is further enhanced by the presence of the static mixer 23) to optimize the mixing of air and fuel in the combustion chamber 7.

[0046] according to Figure 3 The fuel injector 9 is configured to inject at least 80% (and preferably at least 90%-95%) of the fuel onto the inner surface 26 of the feed passage 21; that is, instead of directly directing the fuel to the outside of the feed passage 21, the fuel injector 9 directs the fuel to the inner surface 26 of the feed passage 21, such that the fuel flowing out of the fuel injector 9 initially impacts the inner surface 26 before flowing out of the feed passage 21 through the nozzle 22. The impact of the fuel on the inner surface 26 allows the fuel droplets emitted by the fuel injector 9 to be atomized in a very efficient manner, and by doing so, the mixing of the fuel with the air flowing along the feed passage 21 is significantly improved; the improved mixing between the air and the fuel ensures ideal combustion of the fuel, and in particular complete combustion, thereby preventing partially unburned fuel from flowing out of the combustion chamber 7.

[0047] According to a preferred embodiment, the fuel injector 9 is configured to emit a fuel jet 27 with a hollow, conical shape at its center, i.e., having an annular cross-section, wherein fuel accumulates at the periphery; specifically, according to Figure 3 In the illustrated embodiment, the outer surface of the fuel jet 27 has an opening angle α of approximately 70° (e.g., in the range of 65° to 75°), and the inner surface of the fuel jet 27 has an opening angle β of approximately 50° (e.g., in the range of 45° to 55°). In other words, the fuel injector 9 produces a fuel jet 27 having a conical shape (the apex of the cone is near the ejection nozzle) and a hole at the center (i.e., a region without fuel), which also has a conical shape (the apex of the cone is near the ejection nozzle); therefore, the fuel jet 27 produced by the fuel injector 9 has a conical shell shape due to the presence of the central hole, i.e., a conical shape with an internally hollow interior.

[0048] It should be noted that when we say that the fuel jet 27 produced by the fuel injector 9 has a conical shell shape (i.e., a cone shape with a hollow interior), we mean that most of the fuel flowing out of the fuel injector 9 diffuses within the space of the conical shell, while a very small (residual) portion of the fuel flowing out of the fuel injector 9 can diffuse in a different manner. Furthermore, depending on how the fuel outlet opening is constructed, the fuel jet 27 flowing out of the fuel injector 9 can have a more symmetrical distribution around the longitudinal axis 13 (e.g., ...). Figure 5 (as shown) or a less asymmetrical distribution around the longitudinal axis 13 (as shown) Figure 6 (As shown). In particular, when the fuel injector 9 is of the "vortex" type, the fuel jet 27 flowing out of the fuel injector 9 has Figure 5 The configuration shown, when the fuel injector 9 is of the "orifice" type, the fuel jet 27 flowing out of the fuel injector 9 has Figure 6 The construction shown, ( Figure 6 The image shows a "multi-hole" fuel injector 9 with six exhaust ports, but the number of exhaust ports can vary.

[0049] According to a preferred embodiment, the fuel injector 9 is "vortex" type, that is, it imparts a rotating vortex motion to the injected fuel (i.e., a vortex motion in which the fuel rotates around the longitudinal axis 13 of the tubular body 12).

[0050] As described above, the feed channel 21 is defined on the outside by an outer tubular body 24 (having an inner surface 26 of the feed channel 21) and on the inside by an inner tubular body 25 that surrounds and contains the fuel injector 9.

[0051] according to Figure 3The outer tubular body 24 includes a tapered portion 28 that decreases in size toward the nozzle 22; furthermore, according to the preferred embodiment shown in the figures, the outer tubular body 24 also includes a cylindrical portion 29 disposed downstream of the tapered portion 28 and ending at the nozzle 22. According to different embodiments not shown herein, the outer tubular body 24 does not have the cylindrical portion 29 and therefore includes only the tapered portion 28. According to another embodiment not shown herein, the cylindrical portion 29 may be replaced by another tapered portion having a smaller taper (converging) than the tapered portion 28.

[0052] In the embodiment shown in the accompanying drawings, the fuel injector 9 is configured to inject at least a portion of the fuel onto the cylindrical portion 29 (or further conical portion) of the outer tubular body 24; specifically, the fuel injector 9 is configured to inject the largest portion (almost all) of the fuel onto the cylindrical portion 29 (or further conical portion) of the outer tubular body 24. According to different embodiments, the fuel injector 9 is configured to inject at least a portion of the fuel onto the cylindrical portion 29 (or further conical portion) of the outer tubular body 24 and at least a portion of the fuel onto the conical portion 28 of the outer tubular body 24; for example, the fuel injector 9 is configured to inject approximately half of the fuel onto the conical portion 28 of the outer tubular body 24 and approximately half of the fuel onto the cylindrical portion 29 (or further conical portion) of the outer tubular body 24. According to another embodiment, the fuel injector 9 is configured to inject at least a portion of the fuel onto the conical portion 28 of the outer tubular body 24; in particular, the fuel injector 9 is configured to inject the largest portion (almost all) of the fuel onto the conical portion 28 of the outer tubular body 24.

[0053] according to Figure 2 The axial distance X (measured along the longitudinal axis 13 of the tubular body 12) between the nozzle tip of the fuel injector 9 from which fuel flows (i.e., the injection point of the fuel injector 9) and the longitudinal axis 30 of the spark plug 10 is 33%-100% of the inner diameter D of the tubular body 12 (i.e., the diameter D of the combustion chamber 7); preferably, the axial distance X is 50% to 100% of the inner diameter D of the tubular body 12, and particularly, the axial distance X is 60% to 90% of the inner diameter D of the tubular body 12. It should be noted that the tubular body 12 preferably has a circular cross-section, and therefore, it is undoubtedly necessary to measure the inner diameter D of the tubular body 12 to evaluate the axial distance X; conversely, if the tubular body 12 has an elliptical cross-section, the larger dimension will be considered as the diameter D of the tubular body 12 to evaluate the axial distance X.

[0054] according to Figure 7 and Figure 8 Spark plug 10 has a single internal electrode 31 and a single external electrode 32; according to Figure 9 and Figure 10 The variant shown has a single internal electrode 31 and two external electrodes 32. Figure 9 ) or a single internal electrode 31 and four external electrodes 32 ( Figure 10 According to another variation not shown in this article, there may be three external electrodes 32.

[0055] according to Figure 4 The outer tubular body 24 has a through-hole 33 (i.e., a slit) through which the nozzle tip of the fuel injector 9 (i.e., the injection point of the fuel injector 9) through which fuel flows directly aims at the electrodes 31 and 32 of the spark plug 10. Due to the presence of the through-hole 33, a limited portion 34 of the fuel jet 27 emitted by the fuel injector 9 does not impact the outer tubular body 24, but instead passes through it until it directly reaches the electrodes 31 and 32 of the spark plug 10. In other words, due to the presence of the through-hole 33, the limited portion 34 of the fuel jet 27 directly “wets” the electrodes 31 and 32 of the spark plug 10, thereby creating a localized fuel surplus (i.e., a locally richer mixture) around the electrodes 31 and 32 of the spark plug 10. This facilitates flame ignition and thus supports faster flame propagation to the rest of the mixture.

[0056] according to Figure 4 The through hole 33 is slit-shaped, meaning that the circumferential dimension is greater than the axial dimension; preferably, the angle of the circumferential surface of the through hole 33 is in the range of 30° to 60°.

[0057] according to Figure 8 , 9 In spark plug 10, the outer electrode 32 (or multiple outer electrodes 32) is oriented to not obstruct (cut off) the movement of the fuel jet 27 toward the inner electrode 31 within a limited portion 34; that is, the outer electrode 32 (or multiple outer electrodes 32) of spark plug 10 is oriented to not shield (screen) the inner electrode 31 from the limited portion 34 of the fuel jet 27. As a result, the spark generated between the two electrodes 31 and 32 is thermally shielded (screened) by the outer electrode 32 relative to the limited portion 34 of the fuel jet 27. Figure 8 and Figure 9 The portion 34 of the fuel jet 27 with the correct orientation relative to the electrode 32 (i.e., not shielded by the electrode 32) is shown, as well as the portion 34 of the fuel jet 27 with the incorrect orientation relative to the electrode 32 (i.e., shielded by the electrode 32), and for this reason, this portion is "deprecated" by the symbol "X".

[0058] exist Figure 3 and Figure 4In the illustrated embodiment, the fuel jet 27 emitted by the fuel injector 9 is perfectly symmetrical with respect to the longitudinal axis 13 of the tubular body 12 (and the fuel injector 9); that is, the longitudinal axis 13 of the tubular body 12 coincides with the central axis of symmetry 35 of the fuel jet 27. On the other hand, in Figure 11 In the illustrated embodiment, the fuel jet 27 emitted by the fuel injector 9 is asymmetrical with respect to the longitudinal axis 13 of the tubular body 12 (and the fuel injector 9), and therefore, the fuel jet 27 is inclined toward the electrodes 31 and 32 of the spark plug 10; that is, the central axis of symmetry 35 of the fuel jet 27 forms a non-zero angle γ with the longitudinal axis 13 of the tubular body 12. According to a preferred embodiment, the central axis of symmetry 35 of the fuel jet 27 is inclined toward the electrodes 31 and 32 of the spark plug 10, thereby forming an angle γ with the longitudinal axis 13 of the tubular body 12, the width of which ranges from 5° to 20°, and is preferably equal to approximately 13° to 15°. Inclining the fuel jet 27 toward the electrodes 31 and 32 of the spark plug 10 allows for localized fuel excess (i.e., a richer localized mixture) around the electrodes 31 and 32 of the spark plug 10, which facilitates flame ignition and thus supports faster flame propagation to the rest of the mixture.

[0059] According to a preferred embodiment, the heating device 6 includes a control unit 36 ​​( Figure 1 (Illustrated in the diagram) It is configured to control the overall operation of the heating device 6, that is, to coordinate the control of the fan 8, the injector 9 and the spark plug 10 in order to achieve the desired goal as efficiently and effectively as possible (i.e., to rapidly heat the processing device 5 without damaging the processing device 5 due to excessive temperature).

[0060] according to Figure 1 In the illustrated possible embodiment, the heating device 6 includes a temperature sensor 37 arranged along the outlet pipe 11 to measure the temperature of the hot air flowing through the outlet pipe 11; alternatively, the heating device 6 includes a temperature sensor 38 arranged along the exhaust pipe 3 downstream of the branch point of the outlet pipe 11 (and upstream of the processing device 5) to measure the temperature of the mixture of exhaust gas and hot air flowing through the exhaust pipe 3. Typically, only one of the two temperature sensors 37 and 38 is used, although both temperature sensors 37 and 38 may be present even in special applications. The control unit 36 ​​uses the readings from the temperature sensor 37 or 38 to control (if necessary, via feedback control) combustion in the combustion chamber 7 to rapidly heat the processing device 5 without damaging it due to excessive temperature.

[0061] The embodiments described herein can be combined with each other without exceeding the scope of protection of this invention.

[0062] The heating device 6 described above has many advantages.

[0063] First, thanks to the ideal mixing between the combustion air introduced by the nozzle 22 of the feed channel 21 and the fuel injected by the fuel injector 9, the heating device 6 ensures that the fuel is completely burned under all operating conditions (especially when a large amount of fuel is injected to generate a large amount of heat) (i.e., no unburned fuel is introduced into the exhaust pipe 3).

[0064] Furthermore, the heating device 6 described above has high thermal power relative to its overall size; that is, even though it is relatively small, the heating device 6 generates high thermal power.

[0065] Finally, the heating device 6 described above is simple and economical to manufacture because it consists of several components with uncomplicated shapes that are easy to connect with standard welds and joints.

[0066] List of reference numerals

[0067] 1. Exhaust System

[0068] 2. Internal Combustion Engine

[0069] 3. Exhaust pipe

[0070] 4. Muffler

[0071] 5. Processing device

[0072] 6. Heating device

[0073] 7 Combustion Chamber

[0074] 8 fans

[0075] 9. Fuel Injectors

[0076] 10 Spark plugs

[0077] 11. Export Pipeline

[0078] 12 Tubular body

[0079] 13. Longitudinal axis

[0080] 14 bottom wall

[0081] 15 bottom wall

[0082] 16 Sidewalls

[0083] 17. Exit opening

[0084] 18. Entrance opening

[0085] 19. Inlet pipe

[0086] 20 Check valve

[0087] 21 Feeding Channel

[0088] 22 nozzles

[0089] 23 Static Mixer

[0090] 24. Outer tubular body

[0091] 25 Inner tubular body

[0092] 26 Inner Surface

[0093] 27 Fuel jet

[0094] 28. Conical section

[0095] 29. Cylindrical section

[0096] 30 Longitudinal axis

[0097] 31 Internal Electrode

[0098] 32 External Electrode

[0099] 33 Through Hole

[0100] Part 34

[0101] 35. Axis of symmetry

[0102] 36 Control Unit

[0103] 37 Temperature sensor

[0104] 38 Temperature Sensor

[0105] α angle

[0106] β angle

[0107] γ angle

[0108] X distance

[0109] D diameter

Claims

1. A heating device (6) for an exhaust system (1) of an internal combustion engine (2); said heating device (6) comprising: A tubular body (12) having a combustion chamber (7) inside; Fuel injector (9), which is mounted through the bottom wall (14) of the tubular body (12) to inject fuel into the combustion chamber (7); At least one inlet opening (18) is available for connection to a fan (8) to receive an airflow that is directed to the combustion chamber (7) and mixed with the fuel. The feed channel (21) receives air from the inlet opening (18), surrounds the end portion of the fuel injector (9) and ends with a nozzle (22), which is arranged around the injection tip of the fuel injector (9); and Spark plug (10), which is mounted through the sidewall (16) of the tubular body (12) to trigger the combustion of the air-fuel mixture and has electrodes; The feed passage (21) is defined on the outside by an outer tubular body (24) having an inner surface (26) of the feed passage (21), and on the inside by an inner tubular body (25) surrounding the fuel injector (9) and containing the fuel injector (9) on the inside. The heating device (6) is characterized in that: The fuel injector (9) is configured to inject at least a portion of the fuel onto the outer tubular body (24); and The outer tubular body (24) has a through hole (33), through which the nozzle tip of the fuel injector (9) directly contacts the electrode of the spark plug (10) to release the fuel.

2. The heating device (6) according to claim 1, wherein, A limited portion (34) of the fuel jet (27) emitted by the fuel injector (9) during use and through the through hole (33) does not strike the outer tubular body (24), but instead passes through the outer tubular body (24) and directly reaches the electrode of the spark plug (10).

3. The heating device (6) according to claim 1, wherein, The through hole (33) is slit-shaped and its circumferential dimension is greater than its axial dimension.

4. The heating device (6) according to claim 1, wherein, The circumferential dimension of the through hole (33) ranges from 30° to 60°.

5. The heating device (6) according to claim 2, wherein: The spark plug (10) has an inner electrode (31) and at least one outer electrode (32); and The outer electrode (32) is oriented to move toward the inner electrode (31) without obstructing the movement of the limited portion (34) of the fuel jet (27) toward the inner electrode (31).

6. The heating device (6) according to claim 2, wherein: The spark plug (10) has an inner electrode (31) and at least one outer electrode (32); and The outer electrode (32) is oriented to not shield the inner electrode (31) from the limited portion (34) of the fuel jet (27).

7. The heating device (6) according to claim 1, wherein, The fuel injector (9) is configured to emit a fuel jet (27) with a hollow cone shape at the center, i.e., with an annular cross-section.

8. The heating device (6) according to claim 7, wherein, The outer surface of the fuel jet (27) has an opening angle (α) of 70° and the inner surface of the fuel jet (27) has an opening angle (β) of 50°.

9. The heating device (6) according to claim 1, wherein, The fuel jet (27) ejected by the fuel injector (9) is asymmetrical with respect to the longitudinal axis (13) of the tubular body (12), causing the fuel jet (27) to tilt toward the electrode of the spark plug (10).

10. The heating device (6) according to claim 9, wherein, The central axis of symmetry (35) of the fuel jet (27) forms a non-zero angle (γ) with the longitudinal axis (13) of the tubular body (12).

11. The heating device (6) according to claim 10, wherein, The angle (γ) between the central axis of symmetry (35) of the fuel jet (27) and the longitudinal axis (13) of the tubular body (12) is 5° to 20°.

12. The heating device (6) according to claim 1, wherein, The fuel injector is configured to inject at least 80% of the fuel onto the inner surface (26) of the feed channel (21).

13. The heating device (6) according to claim 1, wherein, The fuel injector (9) is vortex-shaped and imparts a rotating vortex motion to the fuel.

14. The heating device (6) according to claim 1, wherein, The heating device (6) includes a static mixer (23) which is annular, arranged around the fuel injector (9) along the feed channel (21) and configured to generate turbulence in the air flowing toward the nozzle (22).

15. The heating device (6) according to claim 1, wherein, The heating device (6) includes a static mixer (23) which is annular, arranged around the fuel injector (9) along the feed channel (21) and configured to generate vortex motion in the air flowing toward the nozzle (22).

16. An exhaust system (1) for an internal combustion engine (2); said exhaust system (1) comprising: Exhaust pipe (3), which starts from the exhaust manifold of the internal combustion engine (2) and ends at the muffler (4), from which exhaust gas is released into the atmosphere; Exhaust gas treatment device (5), said exhaust gas treatment device (5) being arranged along said exhaust pipe (3); and According to claim 1, the heating device (6) is connected to the exhaust pipe (3) upstream of the exhaust gas treatment device (5) via an outlet pipe (11) from the exhaust pipe (3), and is designed to generate a hot airflow by burning fuel.

17. The system according to claim 16, wherein, The heating device includes: Temperature sensors (37, 38) are arranged along the outlet pipe (11) or along the exhaust pipe (3) downstream of a branch point of the outlet pipe (11); and The control unit (36) also regulates combustion in the heating device (6) based on measurements provided by the temperature sensors (37, 38).

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