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Patent Searching and Data


Title:
SYSTEM AND METHOD FOR CLEANING A PARTICULATE FILTER
Document Type and Number:
WIPO Patent Application WO/2014/016635
Kind Code:
A1
Abstract:
The system (50) is intended to be arranged upstream from a filter in a flow of gases directed towards said filter for allowing the cleaning thereof. It comprises a rotational actuator (56) rotating a rotating member (51) about an axis (52) parallel to the gas flow direction. The first rotating member has a wall portion (53) is capable of blocking the gas flow towards the filter and comprising openings (54). The total area of the openings is small compared to the wall portion area, for allowing the gases to flow through said openings towards a small part of the filter cross section at a given moment, the openings being arranged in the wall portion so that, following a revolution of the first rotating member, a gas flow has passed through the openings towards substantially the whole cross section of the filter.

Inventors:
VERBO LADISLAF (FR)
Application Number:
PCT/IB2012/001809
Publication Date:
January 30, 2014
Filing Date:
July 26, 2012
Export Citation:
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Assignee:
RENAULT TRUCKS (FR)
VERBO LADISLAF (FR)
International Classes:
F01N3/021; F01N3/023
Foreign References:
JPS63259115A1988-10-26
US20040226290A12004-11-18
JP2003097248A2003-04-03
Other References:
None
Attorney, Agent or Firm:
CABINET GERMAIN & MAUREAU (Lyon Cedex 06, FR)
Download PDF:
Claims:
CLAIMS

1. A system intended to be arranged upstream from a particulate filter (18) of a vehicle (1 ) having an internal combustion engine (4), in a flow (F) of gases directed towards said filter (18) for allowing the cleaning of said filter (18), the system (50) comprising:

a first rotating member (51 ) capable of rotating about a rotational axis (52) which, in use, is substantially parallel to the gas flow direction (F2), the first rotating member (51) having a wall portion (53) which is capable of blocking the gas flow (F) towards the filter (18) and which comprises at least one opening (54), the total area of the opening(s) (54) being small compared to the wall portion area, for allowing the gases to flow through said opening(s) (54) towards a small part of the filter cross section at a given moment, the opening(s) (54) being arranged in the wall portion (53) so that, following a revolution of the first rotating member (51), a gas flow has passed through the opening(s) (54) towards substantially the whole cross section of the filter (18);

a first rotational actuator (56) capable of rotating the first rotating member (51 ) by means of the flow of gases, in a first direction (D1 ).

2. The system according to claim 1 , characterized in that the first rotational actuator (56) comprises at least one blade (57) which is arranged in the gas flow (F), in use, and which is coupled to the first rotating member (51 ). 3. The system according to claim 2, characterized in that the blade(s) (57) is (are) arranged on a shaft (58) which is fastened to the first rotating member (51).

4. The system according to claim 2, characterized in that the blade(s) (57) is (are) arranged directly on the first rotating member (51).

5. The system according to any one of claims 1 to 4, characterized in that at least one opening (54) extends substantially radially, substantially from the rotational axis (52) to the peripheral edge (55) of the first rotating member (51).

6. The system according to any one of claims 1 to 5, characterized in that at least one opening (54) exhibits the shape of a slot.

7. The system according to any one of claims 1 to 6, characterized in that the wall portion (53) of the first rotating member (51 ) comprises four slots (54), each slot (54) extending substantially radially, substantially from the rotational axis (52) to the peripheral edge (55) of the first rotating member (51), the slots (54) being positioned at an angle of about 90° relative to each other.

8. The system according to any one of claims 1 to 7, characterized in that it further includes a second rotating member (68) capable of rotating about the same rotational axis (52) as the first rotating member (51), in a second direction (D2) opposite the first direction (D1), by means of a second rotational actuator (69), the second rotating member (68) being arranged upstream from the first rotating member (51 ) and having a wall portion (70) which is capable of blocking the gas flow (F) towards the filter (18) and which comprises at least one opening (71 ) which, in combination with the opening(s) (54) of the first rotating member (51 ), is arranged to create gas pulses towards the filter (18).

9. The system according to any one of claim 8, characterized in that the second rotational actuator (69) is capable of rotating the second rotating member (68) by means of the flow (F) of gases.

10. The system according to any one of claim 8 or 9, characterized in that the wall portion (70) of the second rotating member (68) comprises two openings (71) which are arranged symmetrically with respect to the rotational axis (52), each opening (70) substantially exhibiting the shape of an angular sector of a disc.

11. The system according to any one of claims 1 to 10, characterized in that it comprises a hollow shaft (58) supporting the first rotating member (51) and the second rotating member (68) when present, the axis of which is substantially coincident with the rotational axis (52), the upstream end (60) of the shaft (58) being at least partially opened, and the downstream end (61) of the shaft (58) being at least partially open so as to be able to blow gas to the central part of the filter cross section which faces the downstream end (61) of the shaft (58). 12. The system according to claim 1 1 , characterized in that the downstream end (61) of the shaft 58 is equipped with a plug (62) having an end wall (63) provided with at least one hole (64) for allowing the gases to flow through said hole(s) (64) towards the filter (18), the total area of the hole(s) (64) being small compared to the area of to the central part of the filter cross section which faces the downstream end (61 ) of the shaft (58), for allowing the gases to flow through said hole(s) (64) towards a small part of the central part of filter cross section at a given moment, the hole(s) (64) being arranged so that, following a revolution of the first rotating member (51), a gas flow has passed through the hole(s) (64) towards substantially the whole cross section of the central part of the filter (18).

13. An arrangement for cleaning a particulate filter (18) of a vehicle (1) having an internal combustion engine (4), the arrangement comprising a particulate filter (18), a device capable of providing or carrying a flow (F) of gases in a flow direction towards said filter (18), and a system (50) according to any one of claims 1 to 12 arranged upstream from the filter (18), in the gas flow (F).

14. An arrangement for cleaning a particulate filter (18) of a vehicle (1) having an internal combustion engine (4), the arrangement comprising a particulate filter (18), a device capable of providing or carrying a flow (F) of gases in a flow direction towards said filter (18), and a system (50) arranged upstream from the filter (18), in the gas flow (F), the system (50) comprising:

- a first rotating member (51 ) capable of rotating about a rotational axis (52) which, in use, is substantially parallel to the gas flow direction (F2), the first rotating member (51) having a substantially transverse wall portion (53) which is capable of blocking the gas flow (F) towards the filter (18) and which comprises at least one opening (54), the total area of the opening(s) (54) being small compared to the wall portion area, for allowing the gases to flow through said opening(s) (54) towards a small part of the filter cross section at a given moment, the opening(s) (54) being arranged so that, following a revolution of the first rotating member (51), a gas flow has passed through the opening(s) (54) towards substantially the whole cross section of the filter (18);

- a first rotational actuator (56) capable of rotating the first rotating member (51) in a first direction (D1).

15. The arrangement according to claim 14, characterized in that the system (50) is according to any one of claims 2 to 12.

16. The arrangement according to any one of claims 13 to 15, characterized in that the device comprises a conduit (13) intended to be connected to the exhaust line of an engine (4). 17. The arrangement according to any one of claims 13 to 15, characterized in that the device comprises a turbine (75).

18. The arrangement according to any one of claims 13 to 17, characterized in that it comprises a muffler (8) intended to be connected to the exhaust line of an engine (4), and in that the filter (18):

is designed to be mounted in an operative position inside said muffler (8) under normal operation of an engine (4) connected to said muffler;

and can be mounted at least partially outside the muffler (8) under cleaning operation in a reverse position as compared with the operative position, thereby freeing up a space into which the system (50) can be removably installed for the cleaning process.

19. The arrangement according to any one of claims 13 to 18, characterized in that the system (50) comprises a housing (65) the cross section of which is substantially identical to the filter cross section or larger than the filter cross section.

20. A method for cleaning a particulate filter (18) of a vehicle (1 ) having an internal combustion engine (4), the method comprising:

- providing a flow of gases (F) directed towards said filter ( 8), over substantially the whole cross section of said filter ( 8); providing a first rotating member (51 ) in the gas flow (F), upstream from said filter (18), the first rotating member (51 ) having a wall portion (53) which is capable of blocking the gas flow (F) towards the filter (18) and which comprises at least one opening (54), the total area of the opening(s) (54) being small compared to the wall portion area of the first rotating member (51 ), for allowing the gases to flow th roug h said opening(s) (54) towards a small part of the filter cross section at a given moment, the opening(s) (54) being arranged so that, following a revolution of the first rotating member (51 ), a gas flow has passed throug h the opening(s) (54) towards substantially the whole cross section of the filter (18);

rotating the first rotating member (51 ) by means of a first rotational actuator (56), about a rotational axis (52) which is substantially parallel to the gas flow direction (F2).

Description:
SYSTEM AND METHOD FOR CLEANING A PARTICULATE FILTER

Field of the invention

The present invention relates to the cleaning of a particulate filter, more specifically a particulate filter of a vehicle having an internal combustion engine.

Technological background

Exhaust gases formed in the combustion of fuel in an internal combustion engine may contain a proportion of undesirable components, in particular organic and inorganic particulate matter. The organic particulate is a complex blend of carbon, hydrogen and oxygen, and is a result of incomplete combustion of the diesel fuel in the cylinder. The inorganic portion of the particulate matter has its source in the additives in the lubrication oil or fuel, and material eroded from the engine surfaces. A large part of these inorganic substances consist of metal oxides of sulphur, for example calcium sulphate.

To reduce air pollution, vehicles are therefore equipped with various after-treatment systems that deal with undesirable substances in exhaust gases.

In particular, there can be typically provided filter, for example a diesel particulate filter, which removes un-burnt particulates contained in the exhaust gases. Such a filter may eventually become clogged with the particulates and needs to be regenerated from time to time.

One way of regenerating the filter is to increase the exhaust gases temperature up to a point where the particulates trapped in the filter are oxidized. Such a regeneration makes it possible to remove the organic portion of the particulate matter, since the organic particulate will fully combust during filter regeneration and thus leave the filter as gaseous C0 2 and H 2 0.

The inorganic portion of the particulate matter, on the other hand, cannot be oxidized inside the filter and converted to gaseous components. Instead it is trapped in the filter as various oxides, commonly termed "ash". To maintain acceptable performance, the ash must be periodically removed from the filter to prevent it from clogging.

One conventional method for cleaning a particulate filter, i.e. for removing the ash, is to remove the filter from the engine arrangement and to use a nozzle blowing a gas towards the exit face of the filter, thus blowing the soot out of the wall in the reverse direction to which it was initially deposited.

This method has proved effective in terms of cleaning, but however it requires a long time. Indeed, the nozzle has to be placed successively next to each of the ends of the channels forming the filter so as to successively clean every channel. Another problem with this solution is that all garages or service facilities may not have suitable equipment for filter cleaning. In this case the vehicle may need to be fitted with a replacement filter to remain in operation while the filter is sent to a regeneration unit for being cleaned

This results in an overall process which is complex, since it requires the management of clean filters and filters to be cleaned. This further involves the risk of breaking components. Moreover, this means a need for a store of a larger number of filters, which are relatively expensive, to be maintained by the garage or haulage company, in order to have access to replacement filters at all times, and thus ensure that every vehicle can be equipped with an operational filter.

It therefore appears that, from several standpoints, there is room for improvement in particulate filter cleaning.

Summary

It is an object of the present invention to provide a system, arrangement and method for cleaning a vehicle particulate filter which can overcome the drawbacks of the prior art, by improving the cleaning efficiency and reducing the time required for the cleaning process.

According to a first aspect of the invention, there is provided a system intended to be arranged upstream from a particulate filter of a vehicle having an internal combustion engine, in a flow of gases directed towards said filter for allowing the cleaning of said filter, the system comprising:

- a first rotating member capable of rotating about a rotational axis which, in use, is substantially parallel to the gas flow direction, the first rotating member having a wall portion which is capable of blocking the gas flow towards the filter and which comprises at least one opening, the total area of the opening(s) being small compared to the wall portion area, for allowing the gases to flow through said opening(s) towards a small part of the filter cross section at a given moment, the opening(s) being arranged in the wall portion so that, following a revolution of the first rotating member, a gas flow has passed through the opening(s) towards substantially the whole cross section of the filter;

- a first rotational actuator capable of rotating the first rotating member by means of the flow of gases, in a first direction.

Thus, by means of the rotating member, the invention makes it possible to direct a flow of gases only towards a small portion of the filter, for example towards a limited number of channels of the filter. As a consequence, even if some portions of the filter have already been unclogged, the other portions of the filter will still be cleaned because the gas flow is forced to pass through them since the other portions are blocked by the wall portion of the first rotating member. Moreover, since the gas flow is concentrated towards a limited portion of the filter, its capacity for unclogging said portion is greatly increased.

At the same time, this selective passage of the gas flow through the filter does not require as much time as the prior art method using a nozzle. Moreover, no complex means for moving the first rotating member are needed as opposed to the means used for moving the nozzle from one portion of the filter to another.

Besides, providing a first rotational actuator which makes use of the flow of gases further improves the system simplicity insofar as no additional energy source is needed for rotating the first rotating member. This is also advantageous in that the system architecture can be simplified.

The system according to the invention is therefore simple, effective and easy to implement.

In practice, the term "small" can mean that the total area of the opening(s) covers less than one third, preferably less than 20%, and more preferably less than 10%, of the wall portion area. Then, one given portion of the filter is briefly subjected to the gas flow when one opening is facing said portion. Of course, the term "upstream" relates to the gas flow direction during the cleaning process, which is generally opposite the exhaust gas flow direction in the operative mode in order to enable the removal of ashes.

According to a second aspect, the invention relates to an arrangement for cleaning a particulate filter of a vehicle having an internal combustion engine, the arrangement comprising a particulate filter, a device capable of providing or carrying a flow of gases in a flow direction towards said filter, and a system arranged upstream from the filter, in the gas flow.

The system can be as previously described.

Alternatively, the system can comprise:

- a first rotating member capable of rotating about a rotational axis which, in use, is substantially parallel to the gas flow direction, the first rotating member having a substantially transverse wall portion which is capable of blocking the gas flow towards the filter and which comprises at least one opening, the total area of the opening(s) being small compared to the wall portion area, for allowing the gases to flow through said opening(s) towards a small part of the filter cross section at a given moment, the opening(s) being arranged so that, following a revolution of the first rotating member, a gas flow has passed through the opening(s) towards substantially the whole cross section of the filter;

- a first rotational actuator capable of rotating the first rotating member in a first direction.

According to a third aspect, the invention relates to a method for cleaning a particulate filter of a vehicle having an internal combustion engine, the method comprising:

- providing a first rotating member in the gas flow, upstream from said filter, the first rotating member having a wall portion which is capable of blocking the gas flow towards the filter and which comprises at least one opening, the total area of the opening(s) being small compared to the wall portion area of the first rotating member, for allowing the gases to flow through said opening(s) towards a small part of the filter cross section at a given moment, the opening(s) being arranged so that, following a revolution of the first rotating member, a gas flow has passed through the opening(s) towards substantially the whole cross section of the filter; - rotating the first rotating member by means of a first rotational actuator, about a rotational axis which is substantially parallel to the gas flow direction.

These and other features and advantages will become apparent upon reading the following description in view of the drawing attached hereto representing, as non-limiting examples, embodiments of the invention.

Brief description of the drawings The following detailed description of several embodiments of the invention is better understood when read in conjunction with the appended drawings, it being however understood that the invention is not limited to the specific embodiments disclosed.

Figure 1 is a side view of a vehicle provided with a muffler containing a particulate filter according to an embodiment of the invention;

Figures 2 and 3 show the muffler of figure 1 in its operative position, respectively in perspective from the outside and in schematic longitudinal cross-section;

Figure 4 is an exploded view of the muffler of figure 1 showing the filter;

Figure 5 is a schematic perspective view of the particulate filter; Figure 6 is a perspective view of the muffler of figure 2 with the filter in the cleaning position;

Figure 7 is similar to figure 6 and further shows a suction means connected to the filter for extracting ash;

Figure 8 is a schematic longitudinal cross-section of the muffler of figure 7;

Figure 9 is a schematic perspective view of a system according to a first embodiment of the invention;

Figure 10 shows a variant of the system of figure 9;

Figure 11 is a perspective and partial view of a shaft pertaining to a system according to one embodiment of the invention;

Figure 12 is a schematic longitudinal cross section of a filter and of the system of figure 9 located upstream from said filter during the cleaning process; Figure 13 is a schematic perspective view of a particulate filter in an arrangement according to the invention, showing the gas flowing only through a portion of the filter during the cleaning process;

Figures 14 and 15 schematically show a system according to a second embodiment of the invention, respectively in perspective and in longitudinal cross-section;

Figure 16 shows an arrangement according to an embodiment of the invention, the arrangement comprising a filter and the system of figure 14. Detailed description of the invention

Figure 1 shows a vehicle 1 comprising a chassis 2 and a driver's cab 3 mounted on the chassis. Underneath the driver's cab 3 is an internal combustion engine 4, which acts on the drive wheels 6 of the commercial vehicle 1 by way of a drive train 5. The internal combustion engine 4 comprises an exhaust gas system 7 which typically includes a filter 18, typically a particulate filter, for retaining the particulate matter contained in exhaust gases and preventing them from being released to the atmosphere.

A possible embodiment of the filter 18 is described in more detail with reference to figure 5.

The filter 18 can comprise a canning 40 of generally cylindrical shape having an axis 41 in which is housed a central filtering part 42. The central filtering part 42 generally comprises a network of longitudinally extending channels 43, each channel 43 having an inlet 44 and an outlet 45 for the exhaust gas. The inlets and outlets are alternately closed by a closing wall 46.

In the operative mode, the exhaust gas flows in a direction F1 from the engine 4 towards a first end 35 of the filter 18, where F1 can be substantially parallel to the filter axis 41 . Then, the gas enters the channels 43 which have an open inlet 44, flows in said channels and pass through the longitudinal walls 47 to other channels 43 which have an open outlet 45 (see arrows in Figure 5) before leaving the filter 18 at the second end 25 thereof. The closing walls 46 as well as longitudinal walls 47 of the filtering part 42 are made of an appropriate filtering material which is able to retain the particles contained in the flowing exhaust gas. Such a kind of filter is often called "wall flow", because the exhaust gases have to go through the walls separating one channel open on one side (on the first or second end of the filter) from another channel open on the other side (respectively on the second or first end of the filter) to go through the filter. This is opposed to "flow-through" kind of filter having channels which are each open at their both ends upstream and downstream of the filter.

The material forming the central filtering part 42 can comprise for example silicon carbide (SiC) and/or metallic foam. Preferably, the central filtering part 42 is unitary, composed of one piece of material.

When the filter 1 8 is to be cleaned, and preferably but not necessarily after the organic portion of the particulate matter has been preliminarily burnt, a gas flow is directed in a direction F2 towards the second end 25 of the filter 18, in order to blow the ash out of the walls 46, 47 in the reverse direction to which it was initially deposited. In figure 5, F2 is depicted as being opposite F1 with respect to the filter 18. However, if, for being cleaned, the filter 18 is placed in a reverse position as compared to its operative position, F1 and F2 can be oriented identically with respect to the components surrounding the filter 18.

In practice, in the operative position, the filter 18 can be included in a muffler. For example, as shown in figure 1 , the exhaust gas system 7 of the internal combustion engine 4 can comprise a first muffler 8 provided with an exhaust after-treatment system including said filter 18, and a second muffler 9 connected to a tailpipe which expels the exhaust gases to the atmosphere. The second muffler and the tailpipe can be located to one side of the chassis, as in this example, or extend upwards behind the driver's cab. The invention may also be used without these components.

The first muffler 8, which is installed in the vehicle 1 adjacent to the internal combustion engine 4 and which is attached to the frame of the chassis 2, can be constructed as shown in Figures 2 to 4.

In the depicted embodiment, the muffler 8 is designed in the form of a drum and comprises a front end wall 11 , a rear end wall 12, and a hollow at least partially cylindrical circumferential outside wall 10, which connects both end walls 11 , 12. The muffler 8 comprises an intake conduit 13 and an exhaust conduit 14, for normal operation. The conduits 13, 14 can be provided in the front end wall 11 and/or on the outside wall 10. The muffler 8 may also comprise an internal separating wall 34 extending throughout the inner space of the muffler, dividing the muffler 8 into two separate internal volumes 15, 16. As shown in figure 3, a first volume 15 can contain a first exhaust purifying means in the form of an oxidizing catalyst 17 located downstream from the intake conduit 13 and upstream from the filter 18, the first end 35 of the filter 18 facing the intake conduit 13 in the operative position of the filter 18. A second volume 16 can contain an exhaust purifying means in the form of a selective catalytic reactor 20, or SCR catalyst, located upstream from the exhaust conduit 14. In an implementation, the first and second volumes 15, 16 can be connected by a substantially U-shaped conduit 19, which extends from a first opening 21 to a second opening 22 in the rear end wall 12 of the muffler 8. The filter 18 is then accessible by removal of the conduit 19.

In an alternative embodiment not shown, the first and second volumes 15, 16 can be enclosed by a first and a second outer walls. In such an arrangement, the muffler comprises a first muffler unit and a second muffler unit that can be mounted remote from each other, and connected by a conduit.

Figure 4 shows an exploded view of a portion of the muffler 8 with the filter 18 and the conduit 19 removed.

In an exemplary embodiment, the first opening 21 in the rear end wall 12 can comprise a tubular outlet with a first flange 23 which is arranged to cooperate with and seal against a circumferential flange 24 located adjacent the second end 25 of the filter 18. In the operative position of the filter 8, the second end 25 of the filter 18 faces the first opening 21.

A first ring shaped seal or O-ring 26 is preferably placed between the flanges 23, 24 to ensure that the connection is gas tight during normal operation. A second ring shaped seal or O-ring 27 is preferably placed between the circumferential flange 24 and a first flange 28 at the inlet end of the conduit 19 for the same purpose. Similarly, a third ring shaped seal or O- ring 29 is preferably placed between a second flange 30 at the outlet end of the conduit 19 and a second flange 31 at the second opening 22 in the rear end wall 12.

First and second circular clamps 32, 33 are arranged to hold the filter 8 in place, while clamping the first and second flanges 28, 30 on the conduit 19 onto the first and second flanges 23, 31 , respectively, on the rear end wall 2. The first and second circular clamps 32, 33 have a substantially U- shaped cross-section, allowing them to be placed over the respective flanges and tightened to seal the connection between the first and second volumes 15, 16 inside the muffler 8. The first clamp 32 is also used for clamping the particulate filter 18 to the first flange 23 of the rear end wall 12 when the filter is in its reversed position. The above-mentioned seals can form integral parts of the sealing surfaces and/or comprise separate, removable seals such as O- rings.

The circumferential flange 24 is preferably shaped so that its outer contact surface will seal against both the first flange 28 of the conduit 19 and against the first flange 23 on the rear end wall 12. This allows the filter 18 to be removed from its operative position in the muffler 8, as indicated in Figures 2 and 3, to be reversed and then mounted onto the first flange 23 on the rear end wall 12 in a filter cleaning position, as indicated in Figures 6 to 8.

Periodically, the filter 18 needs to be cleaned to remove the ash which cannot be burnt. For example, for a long-haul vehicle, such a cleaning may be needed every two years. More precisely, there may be provided a monitoring system capable of measuring a value representing the degree of filter clogging and capable of warning the driver that a cleaning is needed. Such a value can be the back pressure or the pressure drop across the muffler 8 or the filter 18, which can be measured by one or several existing pressure sensors connected to an electronic control unit.

The invention makes provision for an arrangement for cleaning a particulate filter of a vehicle 1 having an internal combustion engine 4. The arrangement comprises, in addition to the particulate filter 8, a device capable of providing or carrying a flow of gases in a flow direction towards said filter 18, and a system 50 according to the invention arranged upstream from the filter, in the gas flow.

Here, the term "upstream" relates to the gas flow direction F2 during the cleaning process, which is generally opposite the exhaust gas flow direction F1 in the operative mode, with respect to the filter, in order to enable the removal of ashes.

The system 50 is intended to enable to successively blow gases towards successive small portions of the filter cross section, for example through a limited number of channels 43, to ensure a more efficient cleaning of the whole filter 18 but without requiring a long cleaning period and complex devices. The various components of the system 50 can essentially be made of metal, for example steel, preferably stainless steel.

A first embodiment of the system 50 according to the invention is depicted in figure 9.

The system 50 comprises a first rotating member 51 capable of rotating about a rotational axis 52 which, in use, is substantially parallel to the gas flow direction F2, i.e. the direction along which the gases are directed towards the filter 18 for cleaning it.

The first rotating member 51 has a wall portion 53 which is capable of blocking the gas flow towards the filter 18. In practice, the wall portion 53 can be substantially transverse, i.e. can have a med ian plane substantially perpendicular to the axis 52, which does not necessarily mean that the first rotating member 51 is plane. Alternatively or in combination, the wall portion 53 can have a cross section which is substantially identical to the filter cross section or larger.

In the illustrated embodiments, the first rotating member 51 exhibits the shape of a disc.

Furthermore, in order to allow a gas to flow towards the filter 18, the wall portion 53 comprises at least one opening 54. According to an important feature of the invention, the total area of the opening(s) 54 is small compared to the wall portion area, for allowing the gases to flow through said opening(s) 54 towards a small part of the filter cross section at a given moment. Moreover, the opening(s) 54 are arranged in the wall portion 53 so that, following a revolution of the first rotating member 51 , a gas flow has passed through the opening(s) 54 towards substantially the whole cross section of the filter 18. A revolution is a complete 360° turn of the first rotating member 51.

In concrete terms, the total area of the opening(s) can cover less than one third, preferably less than 20%, and more preferably less than 10%, of the wall portion area.

In practice, at least one opening 54 can extend substantially radially, substantially from the rotational axis 52 to the peripheral edge 55 of the first rotating member 51 . Alternatively, the first rotating member 51 could comprise several openings which do not extend over the whole distance between the rotational axis 52 and the peripheral edge 55 of the first rotating member 51 but which are radially offset the one relative to the others. For example, at least one opening 54 can exhibit the shape of a slot. More precisely, as in the embodiment shown in figure 9, the wall portion 53 of the first rotating member 51 can comprise four slots 54, each slot 54 extending substantially radially, substantially from the rotational axis 52 to the peripheral edge 55 of the first rotating member 51 , the slots 54 being positioned at an angle of about 90° relative to each other.

In the case where the opening 54 is in the form of slot, its shape can for example be that of rectangle extending along a radius of the filter 18, or in the shape of an angular sector of a disc corresponding to the radius of the filter 18.

The system 50 further comprises a first rotational actuator 56 capable of rotating the first rotating member 51 in a first direction D1 around axis 52.

According to an embodiment, the first rotational actuator 56 is capable of rotating the first rotating member 51 by means of the flow of gases. To that end, in practice, the first rotational actuator 56 can comprise at least one blade 57 which is arranged in the gas flow, in use, and which is coupled to the first rotating member 51.

The blade(s) 57 can be arranged on a shaft 58 which is fastened to the first rotating member 51. More specifically, as shown in Fig ure 9, the blade(s) 57 can be arranged axially at a distance from the wall portion 53 along axis 52, preferably upstream of the wall portion in the flow direction F2. The blades 57 may then be connected to one end of a shaft 58 which extends along axis 52 and which has a second end which is fastened to the first rotating member 51.

In a variant illustrated in figure 10, the blade(s) 57 can be arranged directly on the first rotating member 5 . For example, a blade 57 can be formed of a part of the wall potion 53 extending along one radially extending edge of an opening 54. Such a blade 57 can be simply obtained by a local deformation of the wall portion 53 into a suitable profile. I n the embodiment shown on Figure 10, the blades 57 are to contrary arranged on the upstream surface of wall portion 53 between two openings 54, i.e. on a part of the wall portion 53 which blocks the flow of gases towards the filter 18.

Thereby, the blade(s) 57 can be located upstream from the first rotating member 51 , in the gas flow, either at a distance from the first rotating member 51 (figure 9) or on the face 59 thereof which is subjected to said gas flow (figure 10). In the illustrated embodiments, there are provided four blades 57 substantially regularly arranged around the axis 52. In all cases the blade(s) 57 has a profile analogous to that of a fan blade, more or less sophisticated, with the purpose of imparting a rotational movement around axis 52 when impacted by the flow of gases in the direction F2.

Alternatively, the first rotating member 51 could be rotated by other means, such as an electric motor.

According to an implementation of the invention, the shaft 58 supporting the first rotating member 51 can be hollow and have an axis which is substantially coincident with the rotational axis 52. The upstream end 60 of the shaft 58 is at least partially opened, and for example completely opened.

The downstream end 61 of the shaft 58 is also preferably at least partially open so as to be able to blow gas to the central part of the filter cross section which faces the downstream end 61 of the shaft 58. The downstream end 61 of the shaft 58 can be equipped with a plug 62 having an end wall 63 provided with at least one hole 64 for allowing the gases to flow through said hole(s) 64 towards the filter 18. The total area of the hole(s) 64 is preferably small compared to the area of the central part of the filter cross section which faces the downstream end 61 of the shaft 58, for allowing the gases to flow through said hole(s) 64 towards a small part of the central part of filter cross section at a given moment. Moreover, the hole(s) 64 are arranged so that, following a revolution of the first rotating member 51 , a gas flow has passed through the hole(s) 64 towards substantially the whole cross section of the central part of the filter 8. For example, there may be provided a single hole 64 exhibiting the shape of a slot extending from the axis 52 to the peripheral edge of the plug 62.

This disposition makes it possible to efficiently clean substantially the whole filter 18, including the central part of the filter 18.

The system 50 can comprise a housing 65 including the various components of the system, the housing being for example substantially cylindrical. Bearing members 66 are preferably provided to maintain and guide the shaft 58 and other parts of the system 50 within the housing 65.

In concrete terms, for cleaning the filter 18, and as shown in figure 12, there is provided a flow F of gases directed towards said filter 18, over substantially the whole cross section of said filter 18. The direction F2 of the flow F is preferably substantially parallel to the filter axis 41 , and it is oriented from the filter second end 25 towards the filter first end 35, i.e. opposite the direction F1 of the gas flow during the normal operating mode.

The system 50 according to the invention is placed upstream from the filter 18, with respect to direction F2, preferably close to the second end 25 of the filter 1 8 so that the gas flow path can be better controlled. It is advantageous indeed to have the wall portion 53 arranged as close as possible to the second end 25 of the filter 18 in the cleaning position, preferably less than 20 millimeters, and more preferably less than 5 millimeters. In the cleaning position, the axis 41 of the filter 18 and the axis 52 of the system 50 are preferably coincident.

The first rotating actuator 56 makes the first rotating member 51 rotate about the rotational axis 52, either directly by the action of the gas flow F, or by any other appropriate means such as an electric motor.

As a result, one given portion of the filter cross section is briefly subjected to a gas flow when said portion is facing one of the openings 54, as schematically shown in figure 13. Thus, the gas is concentrated and flows in the corresponding channels 43 of the filter 18, i.e. the channels 43 having an open inlet 44 facing the opening 54 at that moment, and crosses the longitudinal walls 47 of said channel 43 to leave the filter 18 by an open outlet 45. The gas flow direction F2 during the cleaning process being opposite the gas flow direction F1 during the normal operating mode, this allows to unclog said portion of the filter 18.

Since the first rotating member 51 rotates, said portion is then placed behind the wall portion 53 of the first rotating member 51. As a result, the gas cannot flow through said portion, but it flows through another portion in order to unclog it.

Thus, even if some channels 43 of the filter 18 have already been cleaned, the system 50 according to the invention will make it possible to clean the other channels 43. Indeed, since only a limited number of channels 43 are available for the gas flow at a given moment, the gas is forced to flow through said channels. By preventing the gas to flow through channels that have already been cleaned, the invention enables a complete and global cleaning of the whole filter 18, by successive sweeping of the channels.

In practice, numerous revolutions of the first rotating member 51 can be required to achieve a satisfactory cleaning of the filter 18. The cleaning process can be performed for a predetermined number of revolutions or for a period of time estimated to result in a sufficient cleaning of the filter 18. In the case of a first rotating member driven by the flow of gases, for example with the use of blades 57, the rotation speed of first rotating member 51 can be adjusted by selecting the number and the shape of the blade(s) 57, and by adjusting the resistance to rotation of first rotating member 51. In all embodiments, the rotation speed of the first rotating member 51 can for example be in the range of 1 to 100 revolutions per minute.

However, the duration of the total cleaning process is fairly short as it can be in the range of 10-15 minutes, for example, depending on the degree of clogging of the filter 18. The filter cleaning can be undertaken during a maintenance phase of the vehicle 1 , which means that there is no need to schedule a specific operation for said cleaning. The unclogging can thus be realized more easily and more often than i n the prior art, wh ich is advantageous in that a more recently deposited ash is easier to remove. Preliminary burning of the organic particulates does not prove necessary.

Then, the particular matter or ash dislodged from the filter 18 is removed for safe disposal.

To that end, an ash collecting device can be attached to the end of the filter 18 by which the gas leaves the filter (i.e. the first end 35). Examples of such ash collecting devices can range from a filter bag attached to the end of the particulate filter, to a hose connector provided with a hose connected to a suction means for assisting the removal of ash. Extracted ash can be removed from the exhaust gas by means of a suitable gas treating device, such as a water scrubber, a cyclone cleaner, an electrostatic filter, a centrifuged air or water filter, or a similar device.

A second embodiment of the system 50 according to the invention is depicted in figures 14 and 15.

In this embodiment, the system 50 further includes a second rotating member 68 which is capable of rotating about the same rotational axis 52 as the first rotating member 51 , in a second direction D2 opposite the first direction D1 , by means of a second rotational actuator 69. The second rotating member 68 is arranged upstream from the first rotating member 51 , preferably very close to said first rotating member 51 (as shown in figure 5) so that the gas flow path can be better controlled. In the illustrated embodiments, the second rotating member 68 exhibits the shape of a disc. The second rotating member 68 has a wall portion 70 which is capable of blocking the gas flow towards the filter 18 and which comprises at least one opening 71 which, in combination with the opening(s) 54 of the first rotating member 51 , is arranged to create gas pulses towards the filter 18.

Creating gas pulses allows a more efficient cleaning of the filter 8.

The above mentioned way of creating said pulses is advantageous in that there is no need to vary the gas flow.

The second rotational actuator 69 can be capable of rotating the second rotating member 68 by means of the flow of gases. To that end, for example, the second rotational actuator 69 may comprise at least one blade 72 which is arranged in the gas flow, in use, and which is coupled to the second rotating member 68, typically arranged on the second rotating member 68. In the illustrated embodiment, there are provided four blades 72 substantially regularly arranged around the axis 52.

Alternatively, the second rotating member 68 could be rotated by other means, such as an electric motor.

The second rotating member 68 is preferably supported by the shaft 58 as previously described.

For example, the wall portion 70 of the second rotating member 68 can comprise two openings 71 which are arranged symmetrically with respect to the rotational axis 52, each opening 71 substantially exhibiting the shape of an angular sector of a disc, for example a quarter of a disc. The number of openings, 71 , their angular extension, and the relative speed of the first and second rotating members will determine the pulsation frequency of the gas flow through the system. For example, the system can be designed so as to create a pulsation frequency in the range of 0.2 to 50 hertz, preferably in the range of 1 to 10 hertz.

While in figures 14 and 15 the first rotational actuator 56 has been depicted as a part separate from the first rotating member 51 , including four blades 57, this shall not be considered as limitative. In particular, for example, the blades 57 could be arranged on the first rotating member 51 , and/or the first rotating member 51 could be rotated by an electric motor. Similarly, the system 50 does not necessarily include a cylindrical housing 65.

According to an embodiment of the invention, the device capable of providing or carrying a flow of gases towards the filter 18 can comprise a conduit intended to be connected to the exhaust line of an engine. In particular, as in the embodiment shown in figures 6 to 8, the muffler 8 is intended to be connected to the exhaust line of the engine 4, by means of the intake conduit 3, and the filter 18 can be unclogged by the flow of exhaust gases in a reverse direction.

In this embodiment, the filter 18:

- is designed to be mounted in an operative position inside said muffler 8 under normal operation of the engine 4 connected to said muffler 8 (see figures 2 and 3);

- and can be mounted at least partially outside the muffler 8 under cleaning operation in a reverse position as compared with the operative position, thereby freeing up a space into which the system 50 can be removably installed for the cleaning process (see in particular figure 8).

"Reverse position" means that the position of the filter axis 41 remains unchanged with respect to the surrounding elements, but the end of the filter 18 which is exposed to the gas flow is the second end 25 and not the first end 35 as in the operative position.

The cross section of the system housing 65 is then preferably substantially identical to the filter cross section so as to fit in the space where the filter 8 is located in the operative position.

When it is determined that the filter 18 is becoming clogged and a cleaning of the filter is required, the filter 8 is disassembled and removed from the rear end wall 2 of the muffler 8.

Then, the filter 18 is reversed and reassembled in a cleaning position at the rear end wall 2 of the muffler 8. Thus, the first end 35 of the filter 18 normally facing the intake conduit 3 on the front end wall 1 1 is open to the atmosphere. With the U-shaped conduit 1 9 removed and the filter 1 8 mounted onto the rear end wall 12, ail exhaust gas will pass through the first volume 15 as the second volume 16 is bypassed, as shown in figure 8.

The exhaust gas is supplied from the intake conduit 13, flows through the first volume 15, the system 50 according to the invention and the filter 18, and passes through a collecting hose 37. The collecting hose 37 is connected to the first end 35 of the filter 18 by means of a hose connector 36 and to a suction means (not shown) for assisting the removal of ash, as indicated by arrow 38. When the cleaning process is over, the engine 4 is stopped, the filter 18 is returned to its operative position inside the muffler 8, and the vehicle 1 is again operational.

With this embodiment, insofar as there exists several sizes of filters 18, it can be necessary to provide several systems 50 each having substantially the same dimensions or cross section than those of the filter 18, so as to fit in the space where the filter 18 is located in the operative position.

Alternatively, when the system 50 is not located in the muffler 8 for the cleaning process, there may be provided a single system 50 for all the sizes of filters 18. In this case, it can be envisaged that the system 50 comprises a housing the cross section of which is larger than the filter cross section.

According to a further embodiment of the invention, the device capable of providing or carrying a flow of gases towards the filter 18 can comprise a turbine.

For example, in the embodiment of the invention shown in figure 16, the turbine 75 is connected to the system 50 arranged upstream from the filter 8. Then, the filter 18 is not located in the muffler 8 during the cleaning process, and the gases used to clean the filter are not the exhaust gases.

This embodiment enables to provide a standalone arrangement, and does not require the engine of the vehicle to be turned on only for cleaning the filter.

The invention is of course not limited to the embodiments described above as examples, but encompasses all technical equivalents and alternatives of the means described as well as combinations thereof.