The present invention relates to a device for removing
pollutants contained in exhaust gases of internal-combustion engines.
As it is known, the pollutants contained in the exhaust
gases of internal-combustion engines are substantially constituted by carbon monoxide
(CO), unburned hydrocarbons (HC), and nitrogen oxides (NO and NO2).
These pollutants are the result of an incomplete combustion
of the mixture of air and fuel (CO and HC) or are inevitable products of the reactions
that occur in the combustion environment (NO and NO2).
Their concentrations depend on many functional parameters
of the engines, including in particular the dosage of the mixture of air and fuel
and the spark advance; the values of these parameters influence in different and
often contrasting ways the noxious emissions, the performance and efficiency of
Many methods and devices are known which are used to remove
noxious emissions and reduce their concentrations; they include the adoption of
particular shapes of the combustion chambers and of the intake ducts which allow
to reach values which are a compromise between the parameters that ensure reduction
of noxious emissions and those which ensure high performance.
Another method that is commonly used to at least partially
reduce noxious emissions is the recirculation of part of the exhaust gases to the
intake of the engine.
Systems for removing noxious emissions are also known which
treat the exhaust gases allowing reactions for complete oxidation of carbon monoxide
(CO) and hydrocarbons (HC) to carbon dioxide (CO2) and water (H2O)
and for reduction of nitrogen oxides (NO and NO2) to nitrogen (N2);
such systems include injection of secondary oxidizing air into the gas exhaust manifold
or catalysis of said reactions.
Catalysis is performed by means of devices known as catalytic
converters, including in particular dual-catalyst converters, i.e. converters which
allow both oxidation of CO and HC and reduction of NO and NO2.
A generic catalytic converter is a muffler which is inserted
in the exhaust manifold and contains a bed on the surface whereof a porous refractory
material is deposited; in turn, such material is impregnated with substances which
catalyze the reactions, e.g. platinum, palladium and rhodium.
Contact between the exhaust gases and the catalytic substances
triggers the reactions for oxidation and reduction of the noxious emissions.
Other removal devices, such as air filters, materials which
selectively adsorb pollutants, additions of substances which facilitate the reduction
of noxious emissions to fuels, or the like are commonly used together with catalytic
FR 1.506.696, issued to M. Michel, Jean, Charles Puisais,
discloses an air cleaner comprising a main tubular body which defines a liquid reservoir
and which is provided with an upper air inlet and a lower drain-plug. Inside the
main body there are two coaxial tubular bodies which are one partially inside the
other so as to define an annular duct. The internal tubular body is at a lower level
and extends in the liquid; the external tubular body extends upwards and defines
an expansion chamber which is provided, at the uppermost end, with a cup on which
a cleaned air outlet is defined. Upstream the air outlet there is a filter. The
air to be cleaned collides against the liquid in which it leaves some of its impurities
and then enters in the annular duct defined between the two tubular bodies; a depression
is thus generated inside the external tubular body where the liquid nebulizes. The
liquid drops collide each other merging together and entrapping the air impurities
and then fall down in the liquid reservoir. The cleaned air flows through the filter
which retains the remaining liquid drops, then the dried cleaned air flows out from
the correspondent outlet.
These conventional methods and devices, however, are not
devoid of drawbacks, including the fact that they do not allow to remove simultaneously
and completely all the different types of noxious emission, that their operating
efficiency depends on the gas treatment time, on the operating temperature and on
particular values of the dosage of the mixture of air and fuel.
For this last reason, they are active only after a significant
period of time has elapsed from engine startup and they require the installation
of particular control and adjustment systems, which increase the complexity of the
structure of such engines.
Moreover, catalytic converters require the adoption of
particular fuels having a controlled content of lead, which poisons them and undermines
their operating effectiveness.
The aim of the present invention is to eliminate the above-noted
drawbacks of the prior art, by providing a device for removing pollutants contained
in exhaust gases of internal-combustion engines which allows to eliminate effectively
and simultaneously all noxious emissions, is active with any kind of fuel, does
not require the installation of particular devices for controlling and adjusting
the operating parameters of the engine, and ensures reduction of noxious emissions
regardless of the time for which they are treated and of the operating temperature.
Within the scope of this aim, an object of the present
invention is to provide a device having a structure which is simple, relatively
easy to provide in practice, safe in use, effective in operation, and relatively
low in cost.
This aim and this and other objects which will become better
apparent hereinafter are achieved by the present device for removing pollutants
contained in exhaust gases of internal-combustion engines, as claimed in claim 1.
Further characteristics and advantages of the present invention
will become better apparent from the detailed description of a preferred but not
exclusive embodiment of a device for removing pollutants contained in exhaust gases
of internal-combustion engines, illustrated only by way of non-limitative example
in the accompanying drawing, wherein the only figure illustrates a schematic view
of a device according to the invention.
With reference to the figure, the reference numeral 1 generally
designates a device for removing pollutants contained in exhaust gases of internal-combustion
engines according to the invention.
The device 1 comprises at least one conveyance duct 2 for
the exhaust gases to be treated, which leads into a tank 3 containing a gas scrubbing
liquid L which is advantageously constituted by water.
Conveyance means are interposed between the conveyance
duct 2 and the tank 3 and are constituted by a fan 4 which is partially immersed
in the liquid L and is turned by transmission means of the belt type 5.
The fan 4 forces the exhaust gases of the engine into the
container 3 of the liquid L.
The conveyance duct 2 is further connected to an auxiliary
air intake duct 6.
A nebulization chamber 7 is arranged above the tank 3 and
communicates with the free surface of the liquid L; the heat of the exhaust gases
arriving from the engine is such as to heat the liquid until it boils and the steam
generated at the free surface, together with the gases that flow through it, enters
the nebulization chamber 7.
Inside the nebulization chamber 7 first screen means are
provided being constituted by walls 8 arranged on staggered planes which are substantially
perpendicular to the flow of the steam and gases.
The steam and gases strike the walls 8, mixing intimately
with each other and forming a dense mist.
A film of condensed liquid forms against the walls 8 and
retains the pollutants, flowing back into the tank 3.
The steam and gases are conveyed into a first lower expansion
chamber 9a and a second upper expansion chamber 9b, which are connected one another
and are arranged in series above the nebulization chamber 7.
The expansion chamber 9a is connected downward of the nebulization
chamber 7, while the upper expansion chamber 9b is connected to at least one duct
10 for the outflow of the treated gases and the steam that has not condensed.
Conveniently, the upper expansion chamber 9b is provided
with second screen means, constituted by second walls 11, and with a drainage duct
12 which discharges the condensate that forms against the walls 11 into a collection
The conveyance duct 2 is provided with a flow control valve
14 which opens when the engine is started, connecting the conveyance duct 2 to the
tank 3, and closes when the engine stops, interrupting the connection between the
conveyance duct 2 and the tank 3.
In this manner, part of the liquid L and part of the steam
are prevented from flowing back towards the engine, causing damage to the cylinders.
In order to reduce engine noise, conventional silencers
15 are provided which are arranged at the auxiliary duct 6.
The lower chamber 9a is provided with plugs 16 for replenishing
the liquid L.
Means 17 for collecting the pollutants retained by the
liquid L are located on the bottom of the tank 3 and are constituted by a tray which
is provided with closure means 18 of the gate-valve type or the like, adapted to
prevent the passage of the liquid during the cleaning and/or maintenance of said
The operation of the invention is as follows: when the
engine is started, the valve 14 opens the conveyance duct 2 and the fan 4 is turned
by the belts 5; in this manner, the exhaust gases of the engine are forced into
the liquid L contained in the tank 3.
After an initial transient period, the heat of the exhaust
gases flowing through the liquid L is such that the liquid boils.
The steam released from the free surface of the liquid
L, together with the gases that flow through it, enters the nebulization chamber
7, where it repeatedly strikes the walls 8; this causes an intimate mixing of the
steam and the gases.
The steam retains the pollutants and the condensation that
forms on the walls 8 flows back towards collection means 17.
After passing through the expansion chambers 9a and 9b,
the residual steam and the treated gases are discharged externally by way of the
outflow duct 10.
The collection means 17 are provided with a gate valve
18, which is open during the operation of the device 1 and is closed when it is
necessary to remove the impurities that have deposited in the collection means 17.
In practice it has been found that the described invention
achieves the intended aim and objects.
Where technical features mentioned in any claim are followed
by reference signs, those reference signs have been included for the sole purpose
of increasing the intelligibility of the claims and accordingly, such reference
signs do not have any limiting effect on the interpretation of each element identified
by way of example by such reference signs.