Power train and isolation of the catalytic converter by negative pressure

Abstract

The invention relates to a power train (10) comprising: - a combustion engine which includes at least one cylinder (11), - a turbocharger (20) including a compressor (21) and a turbine (22) mounted on a rotational shaft (23); and - an exhaust gas treatment device (30) which includes a catalyst (31) and a vacuum chamber (32). According to the invention, the compressor (21) produces negative pressure at its inlet by sucking the air from the negative-pressure tube (41), and the fluid connection between the negative-pressure tube (41) and the vacuum chamber (32) makes it possible to create a vacuum in the chamber, which isolates the catalyst (31).

Description

Description Title of the invention: Powertrain and insulation of the catalytic converter by vacuum [Technical field]

[0001] The invention relates to the field of motor vehicles and in particular the field of pollution control of internal combustion engines of the diesel or gasoline type. In particular, the invention relates to a powertrain and a vehicle comprising such a powertrain.

[0002] In particular, the powertrain comprises a heat engine including in particular a turbocharger and an exhaust gas treatment device which is isolated through a vacuum chamber, the vacuum being generated by the venturi effect by a vacuum tube fluidically connected to the compressor of the turbocharger. [Prior art]

[0003] There is a benefit to thermally insulating an exhaust gas treatment device such as a catalytic converter to treat nitrogen oxides commonly known as NOx. Thermally insulating a catalytic converter reduces the heating time of catalytic converters and makes them more efficient more quickly.

[0004] With this in mind, it is known to create a vacuum between the catalytic converter and a casing surrounding the catalytic converter. The vacuum created in the casing thermally insulates the catalytic converter and allows it to heat up more quickly. The vacuum around the catalytic converter also reduces noise pollution from exhaust gases.

[0005] Documents US 6,162,403 and US 6,203,764 which describe in particular a catalytic converter comprising a vacuum chamber created, during the manufacture of the catalytic converter, by the use of a vacuum welding technique.

[0006] However, the design of these catalytic converters including a design vacuum is very expensive and does not allow for the recovery of possible leaks from the catalytic converter.

[0007] Document FR 2 995 352 describes a technical solution for creating and maintaining a vacuum in the vacuum chamber of the catalytic converter using a venturi system connected to the fresh air supply duct of the intake manifold of the engine cylinder(s).

[0008] However, the inventors realized that such a system did not produce a vacuum effective enough to ensure thorough and constant insulation of the catalytic converter during the engine's operating time.

[0009] The invention aims to overcome all of these drawbacks. [Statement of the invention]

[0010] The invention aims to provide a sufficiently efficient and constant depression in the vacuum chamber of the exhaust gas treatment device while controlling the manufacturing costs of the powertrain.

[0011] The invention aims to optimize the efficiency of the exhaust gas treatment device and in particular to improve its heating time, to provide a constant vacuum, but also to reduce noise pollution.

[0012] To this end, the invention relates to a powertrain comprising: a combustion engine which comprises at least one cylinder, a turbocharger comprising a compressor and a turbine mounted on a rotation shaft of the turbocharger, the compressor supplies fresh air to said cylinder while the turbine is fluidically connected to an outlet of said cylinder, the turbine receives and is rotated by the exhaust gases resulting from the combustion, and an exhaust gas treatment device which comprises a catalyst, a vacuum chamber which is configured to thermally insulate the catalyst and means for producing a vacuum, the gas treatment device being fluidically connected to an outlet of the turbine and receives the exhaust gases.

[0013] The invention is characterized in that the vacuum production means comprise a vacuum tube which is fluidically connected, on the one hand, to the vacuum chamber, and on the other hand, to an inlet of the compressor through an air intake mouth which is positioned coaxially with the rotation shaft of the turbocharger, the compressor producing a vacuum at its inlet by sucking air from the vacuum tube, the fluid connection between the vacuum tube and the vacuum chamber then makes it possible to create a vacuum in said chamber which isolates the catalyst.

[0014] The inventors surprisingly discovered that at the turbocharger inlet, the compressor produces a higher vacuum in a coaxial area of ​​the compressor's rotation shaft. The positioning, in this specific area, of the air intake opening of the vacuum tube makes it possible to provide an optimal vacuum in the vacuum chamber which isolates the catalyst. The vacuum produced is obtained by the venturi effect and maintained throughout the operation of the engine by the vacuum produced at the turbocharger inlet, this vacuum being communicated to the vacuum chamber via the vacuum tube.

[0015] In embodiments, the air intake vent may be positioned at a minimum distance of 10 mm from the compressor. This minimum distance helps to avoid that the vacuum tube does not disrupt the normal operation of the compressor.

[0016] In embodiments, the powertrain may include means for positioning the vacuum tube so as to position the air intake opening coaxially with the turbocharger rotation shaft. The positioning means make it possible to maintain the air intake opening in an optimal position to produce the highest vacuum.

[0017] In embodiments, the powertrain may comprise a fresh air supply duct which is fluidically connected to the inlet of the turbocharger, the vacuum tube extending at least partially into the supply duct. The passage of the vacuum tube in the fresh air supply duct makes it possible to limit technical modifications to the powertrain. The vacuum production means are thus integrated at a lower cost into the powertrain.

[0018] In embodiments, the diameter of the vacuum tube may be less than the diameter of the fresh air supply duct.

[0019] In embodiments, the positioning means may comprise spacers that are integral with the internal walls of the supply duct. The spacers make it possible to maintain the vacuum tube and the air intake mouth in a determined position during operation of the engine. It is thus possible to maintain a constant vacuum during operation of the engine within the vacuum chamber.

[0020] In embodiments, the vacuum tube can enter the supply duct through an opening provided in the wall of the supply duct, the powertrain comprising a joining member which ensures at said opening, on the one hand, the fixing of the vacuum tube to the wall of the supply duct, and on the other hand, the sealing of the supply duct. The joining member makes it possible to maintain the optimal operating efficiency of the powertrain while improving the longevity of the assembly between the vacuum tube and the supply duct.

[0021] In embodiments, the joining member may comprise mechanical adjustment means which are configured to fix the vacuum tube to said wall and to adjust the sealing of the supply conduit at the opening.

[0022] In embodiments, the joining member may position and maintain the air intake vent away from the compressor.

[0023] The invention also relates to a vehicle comprising a powertrain according to the invention. [Description of the drawings]

[0024] Other characteristics and advantages of the invention will become apparent from reading the description which follows. This description is purely illustrative and must be read in conjunction with the appended drawings in which:

[0025] [Fig. 1] is a schematic representation of a powertrain according to one embodiment of the invention, the powertrain notably comprising a turbocharger.

[0026] [Fig. 2] is a schematic representation of a vacuum tube positioned at the inlet of a compressor of the turbocharger of the powertrain of Figure 1.

[0027] [Fig. 3] is a schematic representation of the arrangement of the vacuum tube relative to the turbocharger according to one embodiment of the invention and in which the fresh air supply duct has a curved configuration.

[0028] [Fig. 4] is a schematic representation of the arrangement of the vacuum tube relative to the turbocharger according to one embodiment of the invention and in which the fresh air supply duct has a straight configuration.

[0029] [Fig. 5] is a schematic representation of means for positioning an air intake opening of the vacuum tube according to the invention.

[0030] [Fig. 6] is a schematic representation of an embodiment of a cross-section of a connecting member according to the invention which ensures the passage of the vacuum tube into the fresh air supply duct of the cylinder. [Description of embodiments]

[0031] With reference to Figure 1, the invention relates to a powertrain 10 in particular for a land vehicle such as a motor vehicle. The invention also relates to a vehicle comprising this powertrain 10.

[0032] As illustrated in Figure 1, the powertrain 10 comprises a combustion engine which comprises at least one cylinder 11. In the embodiment of Figure 1, the cylinder(s) 11 which are supplied with fresh air by a fresh air manifold 12 and the exhaust gases from the cylinder(s) 11 are recovered at the outlet of the cylinder(s) 11 by an exhaust manifold 13. The exhaust manifold is fluidically connected at the outlet of said cylinder 11 and configured to evacuate the exhaust gases from said cylinder 11.

[0033] As illustrated in Figure 1, the powertrain 10 comprises a turbocharger 20 comprising a compressor 21 and an expansion turbine 22. The compressor 21 and the expansion turbine 22 are mounted on the same rotation shaft 23 of the turbocharger 20. In this example, the compressor 21 supplies fresh air to the cylinder(s) 11 through the fresh air manifold 12. In particular, the powertrain 10 comprises a fresh air supply duct 14 which is fluidly connected, through the compressor 21, to the fresh air manifold 12. In the example of FIGS. 3 and 4, the supply duct 14 is connected to an air intake cone 24 of the turbocharger 20. Here, the intake cone 24 is arranged at the inlet of the compressor 21. The turbine 22 is fluidly connected to an outlet of the cylinder 11 via the exhaust manifold 13. As a result, the turbine 22 receives and is rotated by the exhaust gases from the combustion taking place in the cylinder 11.

[0034] As illustrated in Figure 1, the powertrain 10 also comprises an exhaust gas treatment device 30 which comprises a catalyst 31 and a vacuum chamber 32 which is configured to thermally insulate the catalyst 31. The treatment device 30 is fluidically connected, by a first end, to the outlet of the turbine 22 by an exhaust duct 15. A second end 33 of the treatment device 30 opens into the atmosphere in order to evacuate the exhaust gases after treatment. The invention does not relate to the treatment of the exhaust gases but only to the insulation of the catalyst to optimize its action.

[0035] The powertrain 10 further comprises vacuum production means 40, the gas treatment device 30 being fluidically connected to an outlet of the turbine 22 and receiving the exhaust gases.

[0036] As illustrated in Figures 1 to 4, the vacuum production means 40 comprise a vacuum tube 41. A first end of the vacuum tube 41 is fluidically connected to the vacuum chamber 32. The second end of the vacuum tube 41 is constituted by an air intake mouth 42. Advantageously, the mouth 42 is positioned at the inlet of the compressor 21 coaxially with the rotation shaft 23 of the turbocharger 20. Thus, as illustrated in Figures 2 to 4, the mouth 42 and the rotation shaft 23 of the turbocharger 20 extend along the same axis AA. In these same figures, the mouth 42 opens into the intake cone 24 of the turbocharger 20.

[0037] As illustrated in Figures 3 and 4, the inventors have surprisingly discovered that the area of ​​the intake cone 24 where the greatest depression is located corresponds to an area at the inlet of the compressor 21 which extends around the axis AA which corresponds to the axis along which the rotation shaft 23 of the compressor 21 extends. This depression is materialized by curved lines 25 symbolizing the flow of air sucked in by the compressor 21.

[0038] The compressor 21 produces a vacuum at its inlet by sucking in particular the air from the vacuum tube 41 but also the fresh air which circulates in the fresh air supply duct 14. The fluid connection between the vacuum tube 41 and the vacuum chamber 32 makes it possible to create a vacuum in said chamber, thus isolating the catalyst 31.

[0039] According to one embodiment of the invention, the air intake mouth 42 is positioned at least 10 mm away from the compressor 21.

[0040] According to the embodiments, the power unit 10 which comprises means 50 for positioning the vacuum tube 41 in the intake cone 24 so as to position the air intake mouth 42 coaxially with the rotation shaft 23 of the turbocharger 20 but also to position this mouth 42 at a distance from the compressor according to the invention.

[0041] According to embodiments illustrated in Figures 1, 3 and 4, in order to position the mouth 42 coaxially with the rotation shaft 23 of the turbocharger 20, the vacuum tube 41 extends at least partly into the feed duct 14. Other configurations may be envisaged in accordance with the invention, for example, by using a two-way Y-connector at the intake cone 24, one way for connecting the feed duct 14 to the inlet of the turbocharger 20 and one way for connecting and positioning the vacuum tube 41. It is also possible to modify the intake cone 24 to allow the mouth 42 to be optimally positioned in accordance with an embodiment of the invention. However, these configurations are more expensive than the embodiment described in this document.

[0042] In particular, according to the embodiments illustrated in Figures 3 and 4, the vacuum tube 41 extends partly into the fresh air intake duct 14. For this purpose, the diameter of the vacuum tube 41 is less than the diameter of the fresh air supply duct 14. According to a particular embodiment, the positioning means 50 may comprise spacers 51 which are integral with the vacuum tube 41 and the walls of the supply duct 14. As illustrated in Figures 3 to 5, the positioning means 50 may comprise a ring 52 which encloses the vacuum tube 41. The vacuum tube 41 may be mounted to slide relative to the ring 52 or be integral with the latter. For example, the ring 52 may be welded to the vacuum tube 41. The spacers 51 are integral with the ring 52 and extend, in particular radially, towards a peripheral edge 53.

[0043] In this example, the peripheral edge 53 is annular in order to cooperate with the walls of the supply duct 14 which has a circular cross-section. However, depending on the configuration of the supply duct 14, the peripheral edge 53 may have different shapes. Furthermore, in order to ensure that the mouth 42 is held in the optimal position in accordance with the invention, the peripheral edge 53 may be welded to the inner wall of the supply duct 14.

[0044] According to the embodiments illustrated in Figures 3 and 4, the vacuum tube 41 enters the supply duct 14 through an opening 140 formed in the wall of the supply duct 14. In this configuration, the powertrain 10 may comprise a joining member 60 which ensures, on the one hand, the attachment of the vacuum tube 41 to the wall of the supply duct at the opening 140. The joining member 60 also ensures the sealing of the supply duct 14 at the opening 140.

[0045] According to a particular embodiment, the joining member 60 may comprise mechanical adjustment means configured, on the one hand, to fix the vacuum tube 41 to the wall of the sealing duct 14, and on the other hand, to adjust the sealing of the supply duct 14 in particular at the opening 140.

[0046] For example, as illustrated in Figure 6, the connecting member 60 may comprise a threaded male end piece 61 which is integral with the outer wall of the fresh air supply duct 14. Advantageously, this end piece 61 may have an internal conical sleeve 62 against which a seal 63 made of elastic materials such as silicone or rubber may be pressed. The connecting member 60 may also comprise a threaded nut 64 complementary to the end piece 61. To facilitate the intelligibility of Figure 6, the connecting member 60 is shown unassembled while the vacuum tube 41 passes through the opening 140 and is positioned in the fresh air supply duct 14. The seal 63 and the nut 64 are shown threaded onto the vacuum tube 41 and ready to be assembled to the end piece 61 in order to ensure the sealing of the opening 140 and to ensure the fixing of the vacuum tube 41 on the fresh air supply duct 14.The seal 63, the nut 61 and the conical sleeve 62 can then be considered as mechanical adjustment means.

[0047] Advantageously, the connecting member 60 positions and maintains the air intake vent at a distance from the compressor 21 in accordance with one embodiment of the invention. This mechanical fixing limits the play of the vacuum tube 41 relative to the supply duct 14 and makes it possible to extend the service life of the powertrain 10.

[0048] Figure 3 illustrates a particular embodiment, in which the fresh air supply duct 14 is bent close to the intake cone 24. In this embodiment, the opening 140 is advantageously arranged at the level of the curvature of the supply duct 14. This particular arrangement makes it possible to use a vacuum tube 41 whose section, which enters and extends into the supply duct 14, is straight. The positioning of the mouth 42 is then facilitated during assembly of the powertrain group 10.

[0049] Figure 4 illustrates another embodiment, according to which the fresh air supply duct 14 is straight as it approaches the intake cone 24 of the turbocharger 20. According to this configuration, the vacuum tube 41 comprises a bent section inside the supply duct 14 in order to position the mouth 42 in the axis AA.

Claims

Claims

1. Powertrain (10) comprising: a combustion engine which comprises at least one cylinder (11), a turbocharger (20) comprising a compressor (21) and a turbine (22) mounted on a rotation shaft (23) of the turbocharger (20), the compressor (21) supplies fresh air to said cylinder (11) while the turbine (22) is fluidically connected to an outlet of said cylinder (11), the turbine (22) receives and is rotated by the exhaust gases resulting from the combustion, an exhaust gas treatment device (30) which comprises a catalyst (31), a vacuum chamber (32) which is configured to thermally insulate the catalyst (31) and vacuum production means (40), the gas treatment device (30) being fluidically connected to an outlet of the turbine (22) and receives the exhaust gases, characterized in that the vacuum production means (40) comprise a vacuum tube (41) which is fluidly connected, on the one hand,to the vacuum chamber (40), and on the other hand, to an inlet of the compressor (21) through an air intake mouth (42) which is positioned coaxially with the rotation shaft (23) of the turbocharger (20), the compressor (21) producing a vacuum at its inlet by sucking air from the vacuum tube (41), the fluid connection between the vacuum tube (41) and the vacuum chamber (32) makes it possible to create a vacuum in said chamber which isolates the catalyst (31).,

2. Powertrain (10) according to claim 1, wherein the air intake mouth (42) is positioned at a minimum distance of 10 mm from the compressor (21).

3. Powertrain (10) according to one of claims 1 and 2, which comprises positioning means (50) of the vacuum tube (41) so as to position the air intake mouth (42) coaxially with the rotation shaft (23) of the turbocharger (20).

4. Powertrain (10) according to one of claims 1 to 3, which comprises a fresh air supply duct (14) which is fluidically connected with the inlet of the turbocharger (20), the vacuum tube (41) extending at least partly in the supply duct (14).

5. Powertrain (10) according to claim 4, wherein the diameter of the vacuum tube (41) is less than the diameter of the fresh air supply duct (14).

6. Powertrain (10) according to claims 3 and 4, wherein the positioning means (50) comprise spacers (51) which are integral with the internal walls of the supply duct (14).

7. Powertrain (10) according to one of claims 4 to 6, in which the vacuum tube (41) enters the supply duct (14) through an opening (140) formed in the wall of the supply duct (14), the powertrain (10) comprising a joining member (60) which ensures at said opening (140), on the one hand, the fixing of the vacuum tube (41) to the wall of the supply duct (14), and on the other hand, the sealing of the supply duct (14).

8. Powertrain (10) according to claim 7, wherein the joining member (60) comprises mechanical adjustment means which are configured to fix the vacuum tube (41) on said wall and to adjust the sealing of the supply duct (14) at the opening (140).

9. Powertrain (10) according to claims 2 and 7, wherein the connecting member (60) positions and maintains the air intake mouth (42) at a distance from the compressor (21).

10. Vehicle comprising a powertrain (10) defined according to one of claims 1 to 9.

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