EP4051886B1

EP4051886B1 - An exhaust pipe for exhaust gas of an internal combustion engine of a vehicle

Info

Publication number: EP4051886B1
Application number: EP20800739.3A
Authority: EP
Inventors: Franciscus Thomas Everardus JANSSEN; Jemil Gael ZNAIEN; Nils GOETELEN
Original assignee: DAF Trucks NV
Current assignee: DAF Trucks NV
Priority date: 2019-10-29
Filing date: 2020-10-27
Publication date: 2023-10-18
Anticipated expiration: 2040-10-27
Also published as: WO2021086177A1; EP4051886C0; EP4051886A1; NL2024114B1

Description

The invention relates to an exhaust pipe for exhaust gas of an internal combustion engine of a vehicle, said vehicle having a bottom, said exhaust pipe having an exhaust gas passage for passing exhaust gas, said exhaust pipe having a circular inlet opening, in use, capable of being in exhaust receiving communication with an exhaust system of the vehicle; an outlet opening for discharging exhaust gas into the surroundings external to the vehicle, and a curved exhaust pipe section positioned between the circular inlet opening and the outlet opening, wherein an inner surface of a first annular portion of the curved exhaust pipe section gradually changes from a convex circular section to an indented concavely curved section in a direction from the inlet opening towards the outlet opening, for - in use - creating turbulence or a vortex in the exhaust gas flowing through the curved exhaust pipe section of the exhaust gas passage, wherein the curved exhaust pipe section comprises a curved inside pipe section and a curved outside pipe section, the curved inside pipe section having a smaller radius of curvature than the curved outside pipe section.
Such an exhaust pipe for a vehicle is known from WO2017116326A1 . The exhaust pipe known from WO2017116326A1 comprises an inner pipe in flow communication with the combustion engine, an outlet enclosure having a semi-closed structure leading to an exhaust gases outlet plane which is oriented to extend parallel to the road surface on which the vehicle moves (and thus parallel to the bottom of the vehicle) and a connection element joining the inner pipe and the outlet enclosure while creating air intake gaps for intaking environmental air contributing to the temperature drop of the exhaust gas streams. The outlet enclosure comprises a curved exhaust pipe section having a curved inside pipe section and a curved outside pipe section, the curved inside pipe section having a smaller radius of curvature than the curved outside pipe section. The outlet enclosure has a first lobe and a second lobe separated by an inwardly projecting and downwardly expanding deflection portion which is arranged in the curved outside pipe section. This deflection portion is structured to directly face and receive gas streams coming from the inlet pipe in the manner that, due to an asymmetry of the first and second lobes with respect to each other, separate vortices are created to cool the temperature of the exhaust gases. Thus, in the exhaust pipe known from WO2017116326A1 the air from the environment mixes with the exhaust gas, whereby the temperature of the exhaust gas, in particular at an exhaust gas outlet or an outlet region of the exhaust pipe, can be reduced. However, there is a constant desire in the field to improve the reduction of temperature of exhaust gas, in particular during burning off soot of a soot filter. This burning off process usually takes place under driving conditions of the vehicle, however in some cases this burning off process is performed or has to be finished during a stand still operation. During the stand still operation however the ambient air flow around the exhaust pipe to cool down the exhaust gasses to an acceptable low level might be insufficient even when the known exhaust pipe is used.
It is thus an object of the present invention to provide an alternative exhaust pipe for exhaust gas of an internal combustion engine of a vehicle with which the temperature of exhaust gases can be reduced sufficiently even in a stand still operation.
In order to achieve this object the invention provides an exhaust pipe for exhaust gas of an internal combustion engine of a vehicle, said vehicle having a bottom, said exhaust pipe having an exhaust gas passage for passing exhaust gas, said exhaust pipe having a circular inlet opening, in use, capable of being in exhaust receiving communication with an exhaust system of the vehicle; an outlet opening for discharging exhaust gas into the surroundings external to the vehicle, and a curved exhaust pipe section positioned between the circular inlet opening and the outlet opening, wherein an inner surface of a first annular portion of the curved exhaust pipe section gradually changes from a convex circular section to an indented concavely curved section in a direction from the inlet opening towards the outlet opening, for - in use - creating turbulence or a vortex in the exhaust gas flowing through the curved exhaust pipe section of the exhaust gas passage, wherein the curved exhaust pipe section comprises a curved inside pipe section and a curved outside pipe section, the curved inside pipe section having a smaller radius of curvature than the curved outside pipe section, characterized in that the first annular portion of the curved exhaust pipe section of which the inner surface gradually changes from a convex circular section to an indented concavely curved section in a direction from the inlet opening towards the outlet opening is positioned on the curved inside pipe section. It has appeared that by providing the first annular portion of the curved exhaust pipe section on the curved inside pipe section a strong turbulence is created in the exhaust gas flow which is efficient in reducing the temperature of the exhaust gases discharged from the exhaust pipe even in a stand still operation.
In a further embodiment of an exhaust pipe for exhaust gas of an internal combustion engine of a vehicle according to the invention an inner surface of at least one second annular portion of the curved outside pipe section gradually changes from a circular section to a planar section in a direction from the inlet opening towards the outlet opening. By further providing the inner surface of at least one second annular portion with a gradually change in shape from a circular section to a planar section in a direction from the inlet opening towards the outlet opening the turbulence created in the exhaust gas flow is increased thereby still further improving reduction of the temperature of the exhaust gases discharged from the exhaust pipe. It has appeared that reduction of the temperature of the exhaust gases discharged from the exhaust pipe is sufficient in most operational circumstances when at the outlet opening the inner surface of the outlet opening comprises the indented concavely curved section, and three planar sections, the indented concavely curved section and the planar sections being connected by convexly curved sections.
In a still further embodiment of an exhaust pipe for exhaust gas of an internal combustion engine of a vehicle according to the invention the outlet opening defines an outlet plane, which outlet plane extends transverse to the bottom of the vehicle, and the exhaust pipe comprises a downwardly directed exhaust deflection portion extending from a top of the outlet opening for directing exhaust gases away from the bottom of the vehicle. As a result of the downwardly directed exhaust deflection portion the exhaust gases can be directed away from the bottom of the vehicle, thereby preventing that hot exhaust gases come into contact with components of the vehicle.
The invention will be further explained with reference to the Figures, in which non-limiting exemplary embodiments of a according to the invention are shown:

Figure 1 schematically shows an embodiment of an exhaust pipe for exhaust gas of an internal combustion engine of a vehicle according to the invention in a side perspective view;
Figure 2 schematically shows a cross section of a part of the exhaust pipe for exhaust gas of an internal combustion engine of a vehicle shown in Fig. 1;
Figure 3 schematically shows the embodiment of an exhaust pipe for exhaust gas of an internal combustion engine of a vehicle of Fig 1 in an end perspective view;
Figure 4 schematically shows the embodiment of an exhaust pipe for exhaust gas of an internal combustion engine of a vehicle of Fig 1 in an perspective view shown along the line IV-IV of Fig. 1; and
Figure 5 schematically shows the gradual change from a convex circular section to an indented concavely curved section in a direction from the inlet opening towards the outlet opening of the curved exhaust pipe section of the embodiment of the exhaust pipe shown in Fig. 1.

In Figure 1 an embodiment of an exhaust pipe 1 for exhaust gas of an internal combustion engine of a vehicle according to the invention is schematically shown in a side perspective view. The exhaust pipe 1 has an inner surface 1A and an exhaust gas passage 2 (see Fig. 2) for passing exhaust gas enclosed by the inner surface 1A of the exhaust pipe 1. The exhaust gas passage 2 extends from a circular inlet opening 3 of the exhaust pipe 1 to an outlet opening 4 for discharging exhaust gas into the surroundings external to the vehicle. The circular inlet opening 3 is, in use, capable of being in exhaust receiving communication with an exhaust system of the vehicle.
A curved exhaust pipe section 5 is positioned between the circular inlet opening 3 and the outlet opening 4. The curved exhaust pipe section 5 comprises a curved inside pipe section 6 and a curved outside pipe section 7. As is e.g. clearly shown in Fig. 2 the curved inside pipe section 6 has a smaller radius of curvature than the curved outside pipe section 7.
The curved exhaust pipe section 5 comprises a first annular portion 6A forming a part of the annular circumference of the curved exhaust pipe section 5. As seen from outside of the exhaust pipe the inner surface of the first annular portion 6A of the curved exhaust pipe section 5 gradually changes from a convex circular section at a location 6A1 near the inlet opening 3 to an indented concavely curved section at a location 6A2 which latter location 6A2 is positioned further from the inlet opening 3 than the location 6A1 in a direction from the inlet opening 3 towards the outlet opening 4 as is schematically indicated in Figures 3 and 5, in which the indented concavely curved section is indicated by the reference numeral 6B. According to the invention the first annular portion 6A of the curved exhaust pipe section 5 is positioned on the curved inside pipe section 6. As a result of the change from a convex circular section to an indented concavely curved section in the exhaust gas flowing through the curved exhaust pipe section 5 of the exhaust gas passage 2 a turbulence or vortex is created which is efficient in reducing the temperature of the exhaust gases discharged from the exhaust pipe even in a stand still operation.
In the embodiments shown in the Figures the cross-section of the curved exhaust pipe section 5 is further configured such that an inner surface of at least one second annular portion of the curved outside pipe section 7 gradually changes from a circular convex section to a planar section 6C in a direction from the inlet opening 3 towards the outlet opening 4. Such a planar section 6C is indicated in Figs. 1, 3 and 4. The planer shape of the section 6C is clearly visible in the Figures 3 and 4 near the outlet opening 4, however the change of the circular sectional shape to a planar shape starts in the curved exhaust pipe section 5.
In the embodiments shown in Figures 1, 3 and 4 the exhaust pipe 1 for exhaust gas of an internal combustion engine of a vehicle according to claim 3 the change of the internal shape of the exhaust pipe starting in the curved exhaust pipe section 5 is such that at the outlet opening 4 the inner surface of the outlet opening 4 comprises the indented concavely curved section 6B, and three planar sections 6C, 6D, 6E, wherein the indented concavely curved section 6B and the planar sections 6C, 6D, 6E are connected by convexly curved sections 8A, 8B, 8C, 8D. It has appeared that by using the embodiment shown in these Figures the created turbulence in the exhaust gas flow as a result of the change of inner shape of the exhaust gas passage from a circular cross-section near the inlet opening 3 to the shape with three planar sections 6C, 6D, 6E and an indented concave section 6B connected by convex curved section (8A-8D) as clearly shown in Fig. 4 ensures a sufficient reduction of the temperature of the exhaust gases discharged from the exhaust pipe 1. The change of internal shape of the exhaust pipe 1 takes place at the curved exhaust pipe section 5 and preferably is completed at a distance spaced from the outlet opening 4.
In Figs. 1, 3 and 4 it is shown that the exhaust pipe 1 comprises a downwardly directed exhaust deflection portion 9 extending from a top 10 of the outlet opening 4. As a result of the downwardly directed exhaust deflection portion 9 the exhaust gases can be directed away from the bottom of the vehicle (not shown but with regard to the Figures positioned above the exhaust pipe 1), which bottom of the vehicle extends parallel to the road surface on which the vehicle moves, thereby preventing that hot exhaust gases come into contact with components of the vehicle.

Claims

An exhaust pipe (1) for exhaust gas of an internal combustion engine of a vehicle, said vehicle having a bottom, said exhaust pipe (1) having an exhaust gas passage (2) for passing exhaust gas, said exhaust pipe (1) having a circular inlet opening (3), in use, capable of being in exhaust receiving communication with an exhaust system of the vehicle; an outlet opening (4) for discharging exhaust gas into the surroundings external to the vehicle, and a curved exhaust pipe section (5) positioned between the circular inlet opening (3) and the outlet opening (4), wherein an inner surface of a first annular portion (6A) of the curved exhaust pipe section (5) gradually changes from a convex circular section to an indented concavely curved section (6B) in a direction from the inlet opening (3) towards the outlet opening (4), for - in use - creating turbulence or a vortex in the exhaust gas flowing through the curved exhaust pipe section (5) of the exhaust gas passage (2), wherein the curved exhaust pipe section (5) comprises a curved inside pipe section (6) and a curved outside pipe section (7), the curved inside pipe section (6) having a smaller radius of curvature than the curved outside pipe section (7), characterized in that the first annular portion (6A) of the curved exhaust pipe section (5) of which the inner surface gradually changes from a convex circular section to an indented concavely curved section (6B) in a direction from the inlet opening towards the outlet opening (4) is positioned on the curved inside pipe section (6).
An exhaust pipe (1) for exhaust gas of an internal combustion engine of a vehicle according to claim 1, characterized in that an inner surface of at least one second annular portion of the curved outside pipe section (7) gradually changes from a circular section to a planar section in a direction from the inlet opening towards the outlet opening (4).
An exhaust pipe (1) for exhaust gas of an internal combustion engine of a vehicle according to claim 2, characterized in that at the outlet opening (4) the inner surface of the outlet opening (4) comprises the indented concavely curved section (6B), and three planar sections (6C, 6D, 6E), the indented concavely curved section (6B) and the planar sections (6C, 6D, 6E) being connected by convexly curved sections (8A-8D).
Use of the exhaust pipe (1) according to any one of the preceding claims mounted to a vehicle, characterized in that the outlet opening (4) defines an outlet plane, which outlet plane extends transverse to the bottom of the vehicle, and in that the exhaust pipe (1) comprises a downwardly directed exhaust deflection portion (9) extending from a top (10) of the outlet opening (4) for directing exhaust gases away from the bottom of the vehicle.