FROM MOTOR VEHICLES

DESCRIPTION

Field of the Invention

The present invention refers to a device and related method for the reduction of polluting emissions in exhaust gases from motor vehicles, in particular for the abatement of the particulates present in these emissions, which hence find application in the field of exhaust systems for internal combustion engines.

State of the Art

The whole world is currently experiencing a period of profound environmental crisis mainly due to the needs that modern life imposes on us, to the increased consumption and consequent industrial production, to the thoughtless use of heating means and to the increase of vehicular traffic. This latter factor in particular has a decisive weight in the disastrous environmental situation in which so many cities currently are. Also under the pressure of public opinion and of the associations newly formed in recent years for the protection of environment, there is now a plethora of initiatives from international organizations to local governments aimed at limiting the damages caused by pollution and especially at reducing their causes for the future. Unfortunately, these initiatives usually result in mild remedies such as alternating use of motor vehicles, having purely palliative and apparent effects, while cities continue to be plagued by serious air pollution problems with more than harmful consequences on people's health.

Pollution due to vehicular traffic, in particular, produces pollutants of various types depending on the type of vehicle and fuel for its supply; in general, it can be said, however, that all motor vehicles, whether fueled by diesel, petrol or liquid propane gas, emit nitrogen oxides NOx and particulates in their exhaust gases, as well as other pollutants characteristic of the different types of fuel. Exhaust gases also contribute to the increase in the amount of CO2 present in the atmosphere that is no longer balanced by forests; this gaseous emission is the greenhouse gas that is most responsible for global warming and for rarefaction of the ozone layer surrounding the earth. Particulate matter or PM is among all pollutants in exhaust emissions from internal combustion engines, the one considered to have a greater negative effect on air quality in the cities. This term usually indicates the set of substances, liquid and solid, suspended in the air and made of metals, silica, carbon particles, etc. having a diameter varying between a few nanometres up to 500 micrometres and beyond. Particularly dangerous to people's health is the particulate fraction known as PM10, consisting of particles of diameter less than 10 micrometres that, because of such small size, once inhaled by people, may arrive in the deep airways depending on their size, and even reach the alveolar walls of the lungs, with more or less harmful effects on the respiratory and cardiovascular systems, up to determine the onset of tumours and other serious diseases.

The particulate is dispersed in the air in greater quantities by the exhausts of diesel engines, more and more common among circulating vehicles thanks to reasons of economic savings on the price of fuel, completely unfounded but well rooted in the population. In an attempt to limit the emission of particulate matter, it has become compulsory to install filters that are in fact called anti-particulate filters. Unfortunately, these devices have not proved up to expectations: anti-particulate filters, in particular, are subject to blockages due to the accumulation of particulates that is created over time during the filter operation, with disastrous consequences on the efficiency of filtering but also on the functioning of the engine that is no longer able to correctly emit the exhaust gases. To solve this problem, several systems have been proposed to date for removal of particulates accumulated in the filter, with different methods, known as filter regeneration methods. One of these methods consists, for example, in increasing temperature of the exhaust gases for enough time to generate the combustion of particulates on the filter; this elimination of the particulate by combustion can be facilitated by adding to the fuel products having the effect of lowering the auto-ignition temperature of the particulates. These methods have however already shown their failure: it is in fact known that, in addition to an increase in fuel consumption, the increase in temperature of the exhaust gas also causes conditions that wear the filter itself and may damage it until it breaks.

For the above said reasons the problem of polluting emissions from motor vehicles' exhausts, and in particular the problem of particulates and CO2 emissions, is strongly felt but unfortunately it remains unsolved to date the technical problem of providing a truly effective device in reducing such emissions, which does not involve the drawbacks and limits illustrated above for the known devices.

Summary of the Invention

Scope of the present invention is to provide a device for the abatement of polluting emissions in the exhaust gases of vehicles, particularly useful for reducing particulates and carbon dioxide present in the above said emissions, having a high efficacy of abatement thus contributing to the reduction of atmospheric pollution due to vehicular traffic.

A further scope of the invention is to provide a device of the above said type that may be easily installed in the exhaust system of any kind of vehicles without causing drawbacks in the operations of the engine and in the exhaust system, and without increasing the fuel consumptions.

Still a further scope of the present invention is to provide a device of the above said type that achieve an easy placement inside a vehicle, in particular in the rear luggage compartment while maintaining a large useful space, and which is applicable to all types of motor vehicles, including hybrid vehicles.

Still a further scope of the invention is to provide a device of the above said type that eliminates, or at least significantly reduces, the technical drawbacks highlighted above for the state of the art, in particular a device that is able to accumulate in its inside the noxious emissions and can be easily regenerated maintaining over time a high activity in emissions abatement.

Still a further scope of the present invention is to provide a method efficacious for the abatement of noxious emissions in the exhaust gases of motor vehicles, comprising treating the gases coming from the exhaust system of the vehicles before their entering in atmosphere without the drawbacks highlighted above for the state of the art.

These scopes are achieved by the device and the method according to the present invention, whose essential characteristics are defined in the respective independent claims here attached.

Further important characteristics are included in the dependent claims.

Brief description of the drawings The features and advantages of the device of the invention will be evident from the following exemplary, non-limiting description of an embodiment thereof, with reference to the attached drawings wherein:

- Figure 1 shows a schematic side view of a preferred embodiment of the device of this invention;

- Figure 2 shows an exploded view of the inner components of the device of this invention of Figure 1 ;

- Figure 3 shows a view in detail of a particular embodiment of the perforated element in the device of this invention.

Detailed Description of the Invention

With reference to the figures, and in particular for the moment to the Figure 1 , a device 1 of the invention in an embodiment thereof comprises a tight container 2, that may be advantageously of a substantially cylindrical shape, a pipe E for the inlet of the emissions to be treated coming from the exhaust system of a motor vehicle, in fluid communication with the container 2, and an outlet duct U for the treated gases to go out, always in communication with the container 2.

The container 2 comprises inside a duct 3 upperly connected to the inlet pipe E of the exhaust gases, rising centrally from the bottom of the container 2 in position substantially perpendicular to the container's base. From this duct 3 perforated elements 4, for instance of substantially parallelepiped shape, branch out radially, in communication with the inside of the duct 3. The duct 3 also has a function of supporting the array of perforated elements 4. In the container 2 there is moreover comprised an absorbing solution in such amount as to maintain the perforated elements 4 completely immersed in such solution, also when the vehicle is moving. Advantageously, the absorbing solution's level with stationary vehicle exceeds, for example, of 5-10 cm the height of the elements 4, so as to ensure their complete immersion of the solution even in the event of liquid fluctuations due, for example, to the movement of the vehicle. Thanks to this configuration, the exhaust gas to be treated, entered in the duct 3, is forced to go out through the perforated elements 4 directly inside the absorbing solution; therefore, in the present description, the perforated elements 4 are sometimes collectively indicated, taken as a whole, with the term "bubbler". The container 2 can be advantageously provided with a side duct 21 , easily accessible from the outside, for pouring fresh absorbing solution in the container 2 in case of necessity; preferably, the duct 21 is provided with at least a transparent portion with notches for measuring the solution's volume inside the container, which allow to verify at any time if the solution's level is correct or if on the contrary some fresh solution is to be added.

In the present invention by "absorbing solution" any liquid substance or solution is meant, which is suitable for the abatement of the noxious substances present in the exhaust gases, in particular of the particulate matters and of the carbon dioxide; preferably by "absorbing solution" a concentrated aqueous solution of ethylene glycol is meant, and more preferably an ethylene glycol aqueous solution 50%. These aqueous solutions of ethylene glycol have been widely used also in the automotive industry, in particular as an anti-freezing liquid additive in combustion engines, in fuels and in the tanks for liquids to wash car glasses. As a matter of fact, ethylene glycol generates a cryoscopic lowering and an ebullioscopic raising of water, that respectively make this solution solidify at -38°C and boil at +108°C, therefore the solution remains liquid in a very wide range of temperatures, to also include temperatures in the most extreme weather conditions, from which derives the use as anti-freezing additive or as cooling liquid for radiators in combustion engines. The aqueous solution of ethylene glycol according to the invention can moreover comprise further agents useful for the abatement of the noxious substances in exhaust gases, for instance one or more oxidising agents.

According to the present invention, for each pair of adjacent perforated elements 4, a separation wall 5 is arranged inside the container 2, between said two adjacent perforated elements 4, so as to stabilise the absorbing solution inside the container 2 and to control the horizontal displacement of the liquid during the vehicle's movement in the acceleration and deceleration phases; preferably, the perforated elements 4 are equidistant among each other, as well as the separation walls 5 are. According to a preferred embodiment of the invention, the device 1 comprises eight perforated elements 4 and eight separation walls 5, alternating and at the same distance from each other. According to a particular embodiment of the present invention, both the perforated elements 4 and the separation walls 5 occupy in length all the space available inside the container 2, so as to maximize both the perforated surface for bubbling the gas to be treated inside the solution and the stabilizing effect due to the separation walls 5. Typically, the separation walls 5 are arranged in a radial pattern just like the perforated elements 4, alternating with them.

According to a preferred embodiment of the present device, the elements 4 have the holes positioned on their only surface facing the bottom of the container 2; as a matter of fact, in this way, the gas comes out from the gas bubbler towards the bottom of the container and the residence time of the gas bubbles in contact with the absorbing solution is thus maximised. This can be appreciated in particular from the Figure 3, wherein the numeral 41 indicates the perforated surface of the element 4. Still with reference to the Figure 3, a particular embodiment is illustrated wherein the element has such an inner structure that the gas entering the duct 3 through an inlet hole 43 is directed towards the perforated surface 41 through a curved duct 42.

According to a preferred embodiment of the invention, the holes in elements 4 of the gas bubbler have moreover such dimensions that the gas flow exiting from them towards the solution is finely divided creating micro-bubbles, and typically these holes have a diameter comprised between 0,7 and 5,0 mm, and preferably equal to about 3,5 mm. This preferred feature of the present device allows maximising the efficiency in the treatment of the gas in the absorbing solution all other conditions being the same, thanks to a wider contact surface between the gas bubbles and the solution itself; and moreover, allows an easier ascent of the gas bubbles inside the container facilitating their escape.

The microbubbles of treated gas inside the absorbing solution therefore go upwards inside the container 2, where is present at least a flange 6, at least partially microperforated, parallel to the bottom of the container and of equal diameter, placed above the array of perforated elements 4 and also immersed in the absorbing solution; the microbubbles generated by the bubbling inside the solution, going up in the container 2, so cross this flange 6 where they are further decomposed in order to optimize their "capture" by the absorbing solution. According to a particularly preferred embodiment of the present invention, the container 2 comprises more than a flange 6, for example three flanges 6, parallel among each other, parallel to the bottom of the container and with respect to the array of perforated elements 4, said flanges 6 having microperforated areas arranged in a staggered way to each other, so that the gas bubbles ascending in the container 2 are forced to stay more time in contact with the absorbing solution. Such an embodiment of the present device is illustrated in Figure 2, where it is represented a configuration with three parallel flanges 6, where for example the lower flange can be completely microperforated while the intermediate and the upper flange can have only part of their surface microperforated, preferably such microperforated parts being staggered with respect to each other.

Once passed through the one or more flanges 6, the gas bubbles exiting the surface of the absorbing solution go out from the container through a dedicated hole on the ceiling of the container, which put it into communication with a duct U for the outlet of the gas towards outside. From the duct U the gas can be directly led to the outside of the vehicle for entry into the air or it can be further filtered.

According to a particular embodiment of the present invention, the container 2 may also comprise, in the part above the absorbing solution, at least an anti-particulate filter 7 for the PM10 particulate capture, through which the gas microbubbles are forced to pass before reaching the outlet hole.

Alternatively, or preferably in addition to the anti-particulate filter, the container 2 of the invention may involve the presence, always in the part above the absorbing solution, of one or more passthrough chambers 8, permeable to the gas going up towards the outlet duct U of the container but such as to create a containment of the absorbing solution in case it rise towards the outlet of the container due to vertical displacements of the absorbent liquid during upward movement or downhill of the motor vehicle. Such chambers 8, as well as the filter 7, are preferably easily removable, in order to, for example, wear checks and filter substitutions once it has reached saturation.

According to a preferred embodiment of the present invention, from the inlet pipe E the exhaust gas to be treated is conveyed into a heat exchanger 9 before getting to the duct 3, said heat exchanger being adapted for cooling the exhaust gases to be treated, preferably for bringing their temperature to values close to the room temperature.

According to a preferred embodiment of the invention, the device 1 may further comprise a tank 10 provided in the inside with a special filter for collecting the condensate in order to collect the absorbing solution dragged by the gas bubbles going upwards towards the outlet. When present, this additional tank 10 is provided with pipes for transferring the liquid condensate back inside the container 2 so that it may be used again for the treatment of exhaust gases.

The present device may further comprise a system for the regeneration of the absorbing solution that has accumulated particulate matter from the treatment of the exhaust emissions. This system comprises for example a pipe 1 1 for the withdrawal, at the bottom of the container 2, of the absorbing solution to be regenerated. Through this pipe the solution to be regenerated is conveyed, possibly with the assistance of an electric or mechanical pump 12, to a special filter 13 suitable for the depuration of the solution from the accumulated particulate. Advantageously, also this filter 13 can be easily replaced from the outside once saturated. The so-regenerated solution, through a dedicated pipeline 14, can be transferred back inside the container 2. In this system one or more valves can assist and control the input onto the filter of the solution to be regenerated as well as the inflow into the container 2 of the regenerated solution.

According to a particularly preferred embodiment of the invention a filter 15, which is for example an activated carbon filter, preferably removable, is placed on the path of the outgoing gases in correspondence of the duct U, as illustrated in Figure 1.

It is understood that in the figures herein particular embodiments of the invention are illustrated, while the invention is to be understood as extended to other forms described herein or in any case included in the scope of the invention as defined by the claims. For example, in Figure 1 an embodiment of the present device is illustrated comprising the system of regeneration and recover of the absorbing solution, the heat exchanger 9, as well as the filter 15 for the outgoing gases; however, it is understood that the present invention also refers to embodiments in which said elements are present individually in combination with the above described structure of the container 2.

The device of the invention can be made in shapes and size different from those illustrated in the figures herein, depending on the vehicle where it is to be installed. The installation may comprise the use of one or more special valves at the vehicle's muffler terminal for the purpose of diverting the exhaust gases inside the device of this invention before letting them escape from the exhaust pipe. This valve, or system of valves, is typically calibrated on the vehicle's speed in order to start operating and to determine the flow amount of the exhaust gases diverted into the container on the basis of the vehicle's speed. For instance, for a city route of the vehicle, with speed ranging from 0 to 50 Km/hour, the valve can be completely open thus diverting the whole flow of the exhaust gases from the muffler to the device for treatment in the bubbler; on extra-urban routes, when the vehicle's speed exceeds 50 Km/h, a partial opening of the valve can be envisaged to treat only a part of the exhaust gas, such part being variable with the speed held by the vehicle.

According to a preferred embodiment of the present device, it further comprises sensor means suitable for detecting the level and/or the saturation degree of the absorbing solution inside the container 2 and for signalling these data to an electronic control unit connected to the car dashboard and to its fault warning system. Thanks to these sensor means; the driver may be informed in real time when the solution and/or the external filter require a maintenance service. Further sensor means can be included in the present device for the detection of the saturation degree of the anti- particulate filter 7 and/or of the filter 13 for the regeneration of the absorbing solution, whenever present. Also in this case the detected data may be signalled, by means of a dedicated electronic system, on the dashboard of the vehicle.

The present device can further comprise sensor means for measuring the temperature inside the container 2, by means of a probe installed that is able to detect the temperature inside the container.

In experiments, it was observed that the device of the invention has a high efficiency in the abatement of harmful substances, and in particular of the particulate matters, without requiring for example increased temperature but working under normal pressure and temperature conditions. The present device does not have therefore any influence on the operation of the engine or more in general of the vehicle, or a negative effect on the fuel consumption, as it was on the contrary observed for certain known devices. Apart from the abatement of the particulate matters, the present absorbing solution is also capable of capturing up to 50% of the CO2 emitted by the exhaust system of the vehicle.

The present device is moreover useful for reducing the noxious substances in the exhaust gases of motor vehicles that use any fuel such as methane, liquid propane gas, petrol or diesel; and it is particularly useful for diesel-powered vehicles where the particulate matter is predominant in emissions. The present device is also useful for use in hybrid vehicles, which can combine an electric motor with a traditional petrol or diesel engine.

A first important advantage of the present device with respect to those mentioned above for the prior art is represented by the fact that the particular inner structure of the device allows it to be installed on motor vehicles and to be used during the vehicle's operation and movement under any conditions, without any risks of spills of the absorbing solution outside of the container.

Its compact structure makes possible the installation on vehicles without creating particular encumbrance or weight, in particular it is advantageously possible to insert the present device in the rear luggage compartment of the vehicle below the luggage compartment, to occupy the place that was usually occupied by the spare wheel, nowadays generally no longer present on the vehicle.

A further important advantage of the device and method of the invention is represented by the fact that the absorbing solution used can be an aqueous solution and in general the solutes of possible use, in particular ethylene glycol, that are non- polluting products, completely safe for the environment. The present device, therefore, contrary to other devices used in the field to reduce harmful emissions from motor vehicle exhausts, not only effectively reduces the emission of pollutants into the atmosphere, but it does not introduce other pollutants into the environment.

Still a further advantage of the present device and method is represented by the fact that the absorbing solution can be continuously regenerated inside the exhaust system of the vehicle where it is installed, in an easy, environmental-friendly way, the accumulated particulate residues being collectable on an external filter, which can be easily replaced once saturated. The present invention has been described up to here with reference to preferred embodiments thereof. It should be understood that there may be other embodiments deriving from the same inventive core, all covered by the scope of protection of the claims provided hereinafter.