WO2007115850A1

WO2007115850A1 - An exhaust gas plant for internal combustion engines

Info

Publication number: WO2007115850A1
Application number: PCT/EP2007/051323
Authority: WO
Inventors: Giorgio Girondi
Original assignee: Ufi Filters S.P.A.
Priority date: 2006-04-07
Filing date: 2007-02-12
Publication date: 2007-10-18
Also published as: ITRE20060047A1; ATE447096T1; EP2004963A1; DE602007003001D1; EP2004963B1

Abstract

An exhaust gas plant for internal combustion engines, comprising an exhaust evacuation line (7) of the exhaust gases, an antiparticulate filter (1) located so as to intercept the exhaust evacuation line (7), an auxiliary branch (63) connected to the exhaust evacuation line (7) for by-passing the antiparticulate filter (1), diverter means for deviating (64), for selectively deviating the exhaust gas internally of the auxiliary branch (63), and a control system which commands the diverter means for deviating (64) in accordance with a geographical location of a vehicle to which the exhaust gas plant is associated.

Description

AN EXHAUST GAS PLANT FOR INTERNAL COMBUSTION ENGINES

TECHNICAL FIELD

The invention relates to an exhaust gas plant for internal combustion engines, typically for diesel engines.

More in particular, the invention relates to an exhaust gas plant comprising at least an anti-particulate filter; the plant traps the particulate matter that passes through conventional gas treatment devices located upstream of the filter.

BACKGROUND ART

As is known, one of the main sources of pollution in diesel engines for vehicle traction, usually for buses or automobiles, is the emission into the atmosphere, via exhaust gases, of particulate matter, i.e. a mixture of powders and non-combusted sooty particles, metal oxides and the like, which remain suspended in the air.

To eliminate emission of particulate into the atmosphere, recent years have seen a constant evolution in diesel engines for transport, which, thanks to sophisticated injection systems designed to improve diesel combustion, has led to a drop in particulate production.

Also, passive-type anti-particulate filters have been developed and realised, and are available both as standard equipment and as accessories. These are installed in the terminal tract of the exhaust line, and are designed to trap the particulate and prevent its subsequent release into the atmosphere.

Generally these anti-particulate filters are rather delicate and can be damaged when crossed by exhaust gases and/or gas pressures that are above predetermined critical levels. Owing to this aspect of fragility, exhaust plants that are equipped with a passive anti-particulate filter usually comprise an auxiliary branch which bypasses the filter proper, as well as means for deviating the exhaust gas flow internally of the auxiliary branch when the temperature and/or the pressure of the gases upstream of the means for deviating exceed these predetermined critical limit levels.

Also because of the fragility thereof, passive anti-particulate filters cannot be regenerated on board the vehicle, but have to be dismounted each time they become clogged up, and replaced.

A particularly relevant drawback of the known filters is that they clog up rather rapidly, requiring frequent maintenance operations and resulting in long inactive periods for the vehicles they are fitted on. The applicant has however observed that the use of an anti-particulate filter is necessary especially when the vehicle is used in an urban context, where the use of low gears, frequent accelerations and numerous stops lead to a generally worse combustion of the diesel fuel and therefore to a greater particulate percentage in the exhaust gas; furthermore, the pollution caused in urban contexts is more damaging because of the large number of vehicles in circulation and the high population density.

Conversely, in a non-urban context, the need to filter the exhaust gas is less evident, due both to the smaller quantity of non-combusted particles issuing from the engines and to the lower overall concentration of pollutants and inhabitants in non-urban areas. The aim of the present invention is to provide an exhaust gas plant for internal combustion engines which enables selective use of the anti- particulate filter only when needed, effectively increasing the working life thereof and thus obviating the above-described drawback in the prior art. A further aim of the invention is to attain the above-mentioned aim with a simple, rational and economical solution. DISCLOSURE OF INVENTION

In a general sense the above aims are attained by an exhaust gas plant for internal combustion engines which comprises an exhaust evacuation line for the exhaust gases, an anti-particulate filter intercepting the exhaust evacuation line, an auxiliary branch connected to the evacuation line for bypassing the anti-particulate filter, and means for selectively deviating the exhaust gas into the auxiliary branch. According to the invention, the exhaust gas plant comprises a control system which controls the means for deviating according to the geographical location of the vehicle to which the exhaust gas plant is associated. In more detail, the control system commands the means for deviating in such a way that the flow of the exhaust gas is made to pass exclusively into the anti-particulate filter during urban driving, where the particulate is at its most harmful; while the exhaust gas is made to pass exclusively into the auxiliary by-pass branch during non-urban driving. In this way, exploitation of the anti-particulate filter is efficiently rationalised and the working life thereof consequently increased.

In a preferred embodiment of the invention, the control system comprises a remote device, external and independent of the vehicle, which is destined to interact with an on-board device located on the vehicle itself for detecting the geographical location thereof, for example a technology of the "telepass", citypass" or satellite navigation type, or the like.

Alternatively, the control system can simply comprise a control device of the means for deviating, which is manually activatable by the driver.

BRIEF DESCRIPTION OF DRAWINGS

Further characteristics and advantages of the invention will emerge from the following description, provided by way of non-limiting example with the aid of the accompanying figures of the drawings, in which:

- figure 1 is a schematic view of the exhaust gas plant of the invention;

- figures 2 and 3 illustrate, in longitudinal section, the diverter manifold of figure 1 , shown respectively during operation in an urban zone and during operation in a non-urban zone.

BEST MODE FOR CARRYING OUT THE INVENTION The exhaust gas plant 6 of the present invention comprises a usual exhaust evacuation line 7 for guiding the exhaust gas issuing from an internal combustion engine 8, typically a diesel engine, towards the outside environment.

The exhaust evacuation line 7 is generally intercepted by a plurality of devices for treatment of the exhaust gas, in particular by a catalytic converter - A -

9 and a silencer 10, both of which are crossed in series by the flow of the exhaust gas.

Normally the silencer 10 is located downstream of the catalytic converter 9, with respect to the outflow direction of the exhaust gas. The exhaust evacuation line 7 further comprises a three-way exhaust diverter manifold 60, provided with an inlet duct 61 for the exhaust gas, from which a first outlet terminal 62 and a second outlet terminal 63 branch off. The diverter manifold 60 is located in the terminal tract of the exhaust evacuation line 7, downstream of the catalytic converter 9 and the silencer 10, with respect to the outflow direction of the exhaust gas, or is integrated with the silencer 10 itself.

The first terminal 62 of the manifold 60 is intercepted by a passive filter 1 , which filters the exhaust gas and retains the particulate allowed to pass through the upstream devices, and in particular particulate rated less than PM10, i.e. classifiable as fine particles.

The second terminal 63 is substantially an auxiliary branch which by-passes the passive filter 1 , preventing the exhaust gases from flowing there-through. In the illustrated embodiment, the second terminal 63 terminates directly in the atmosphere, i.e. reaches the outside without being intercepted by any other exhaust gas treatment device.

According to the invention, the exhaust manifold 60 comprises diverter means for selectively deviating the exhaust gas towards the first terminal 62 or the second terminal 63. As illustrated in figures 2 and 3, the diverter means comprise a diverter valve afforded directly internally of the body of the exhaust manifold 60.

The diverter valve is essentially constituted by a butterfly obturator 64 pivoted to the inside of the manifold 60, to which it is mechanically connected by actuator means of known type, for example an electric motor which selectively moves the butterfly obturator 64 between a first and a second work position.

In the first work position the butterfly obturator 64 completely closes the second terminal 63 and opens the first terminal 62 (see figure 2), so that the exhaust gas crosses only the antiparticulate filter 1 ; while in the second work position the obturator 64 opens the second terminal 63 and completely closes the first terminal 62 (see figure 3), sending the entire exhaust gas flow into the atmosphere. According to the invention, the displacements of the butterfly obturator 64 are controlled by a special control system (not illustrated) which detects the geographical location of the vehicle on which the exhaust gas plant 6 is installed, and consequently commands the means for actuating the diverter valve. In more detail, the control system is configured in such a way as to arrange the butterfly obturator 64 in the first work position when the vehicle is in an urban zone, and to arrange the obturator 64 in the second work position when the vehicle is outside an urban zone. In a preferred embodiment of the invention, the control system of the diverter valve comprises a remote device, external and independent of the vehicle, which interacts by means of radio signals or other electronic signals with an on-board device located on the vehicle itself, to reveal the geographical location of the vehicle. Preferably the remote device emits the above-mentioned signals, which are captured and received by the on-board device.

In particular, the remote device can be associated to a fixed station, located for example along a main arterial road for entrance to or exit from a densely- populated centre; the device could be recognisable by a "telepass" or "citypass" type system on-board a vehicle passing by the fixed station. Alternatively, the remote device and the on-board device could be part of a satellite localisation device of the vehicle, which satellite localisation device might include a map of the area the vehicle is travelling in; the device could be of the type known as "sat-nav" appliances. Finally, a simpler but effective application of the invention is where the control system of the diverter valve comprises a manual command organ, for example a button located internally of the cabin of the vehicle, which is manually activatable by the driver. In this case, on entering an urban centre, the vehicle driver can manually commute the diverter valve into the position in which the exhaust gases are forced to pass through the filter 1 ; while on exiting the urban centre, the driver can commute the valve into the position in which the exhaust gases pass through the auxiliary branch 63, directly towards the atmosphere.

Preferably the diverter valve control system, of whatever type, is completed by special sensors (not illustrated) which are designed to detect the pressure and/or the temperature of the exhaust gases upstream of the manifold 60. In this way, the control system causes the butterfly obturator 64 to move into the second work position, i.e. into the position in which it prevents passage of the exhaust gases into the filter 1 , whenever the temperature and/or the pressure of the exhaust gas is above a predetermined threshold limit; this is independent of the geographical position of the vehicle. The threshold limit values include a safety limit, in the sense that they prevent the antiparticulate filter 1 from being subject to internal pressures and/or temperatures which are too high and which might lead to damage to the filter 1.

Obviously an expert in the sector might bring numerous modifications to the exhaust gas plant 6 of the invention, without its forsaking the ambit for which protection is sought and claimed in the following claims.

Claims

1. An exhaust gas plant for internal combustion engines, comprising an exhaust evacuation line (7) of the exhaust gases, an antiparticulate filter (1 ) located so as to intercept the exhaust evacuation line (7), an auxiliary branch (63) connected to the exhaust evacuation line (7) for by-passing the antiparticulate filter (1 ), and diverter means for deviating (64), for selectively deviating the exhaust gas internally of the auxiliary branch (63), characterised in that it comprises a control system which commands the diverter means for deviating (64) in accordance with a geographical location of a vehicle to which the exhaust gas plant is associated.

2. The plant of claim 1 , characterised in that the control system comprises a remote device, external and independent of the vehicle, which interacts with an on-board device located on the vehicle, in order to detect the geographical location thereof.

3. The plant of claim 2, characterised in that the remote device is associated to a fixed station, and can detect a passage of the vehicle in proximity of the fixed station.

4. The plant of claim 2, characterised in that the remote device and the onboard device are part of a satellite system for geographical localisation.

5. The plant of claim 2, characterised in that the remote device emits signals which are received by the on-board device.

6. The plant of claim 2, characterised in that the remove device and the onboard device interact by means of electronic signals.

7. The plant of claim 2, characterised in that the remote device and the onboard device interact by means of radio signals.

8. The plant of claim 1 , characterised in that the control system comprises a manually-activatable device which commands the diverter means for deviating (64).

9. The plant of claim 1 , characterised in that the control system of the diverter means for deviating (64) is configured in such a way that the diverter means for deviating (64) allow passage of the exhaust gas exclusively through the antiparticulate filter (1 ) when the vehicle is travelling in an urban zone, and allow passage of the exhaust gas exclusively through the auxiliary branch

(63) when the vehicle is travelling outside an urban zone.

10. The plant of claim 1 , characterised in that it comprises means for detecting for detecting a pressure and/or a temperature of the exhaust gas upstream of the antiparticulate filter (1 ), which means for detecting are connected to the control system so that the control system can command the diverter means for deviating (64) in order to prevent passage of the exhaust gas through the antiparticulate filter (1 ) when a limit value of pressure and/or of temperature of the exhaust gas is exceeded.

11. The plant of claim 1 , characterised in that the diverter means for deviating

(64) comprise at least a diverter valve located at a tract of the exhaust evacuation line (7) from which the auxiliary branch (63) is derived.

12. The plant of claim 1 1 , characterised in that the diverter valve comprises an obturator (64) which occupies a first work position in which the obturator (64) closes the auxiliary line (63) and a second work position in which the obturator (64) closes a tract (62) of the exhaust evacuation line (7) leading to the antiparticulate filter (1 ).