Patent Application
20180372037
The present invention relates to systems for recirculating blow-by gases into an intake duct of an internal combustion engine, in particular of a motor-vehicle engine. The invention relates, in particular, to a system for recirculating blow-by gases of a known type, comprising:
In internal combustion engines, the blow-by gases that trawl through the clearance between pistons and cylinders of the engine, passing from the cylinders to the engine crankcase, are recirculated to the engine intake after the oil is separated and carried into the crankcase of the engine, which is mixed with the blow-by gases in the form of vapor and/or droplets. The task of the separator device is to allow recirculation of the blow-by gases into the air supply system to the engine, while preventing liquid particles from entering the intake system. Separator devices of the type indicated above are described and illustrated, for example, in the documents EP 2 390 477 A1 and EP 2 653 678 A1, owned by the same Applicant.
When a motor-vehicle equipped with a blow-by gas recirculation system of the above-mentioned type is used at temperatures close to or less than 0° C., there may be ice accumulations around said second end of said tubular element or snorkel, through which the clean blow-by gases are recirculated into the intake duct of the engine. Ice formation is caused by the presence of moisture (water) in the flow of air fed into the intake duct of the engine and/or in the blow-by gas flow. The amount of ice is correlated to the moisture content, the temperature of the air and of the blow-by gases, as well as to the pressure and velocity of the flows of air and gases. If the amount of ice is excessive, it may possibly partially or completely block the passage for recirculating blow-by gases, resulting in a decline in engine performance and with the risk, in extreme cases, of damage to the engine.
A system as set forth in the preamble of claim 1 is known from EP 2 245 279 A1. Similar solutions are known from US 2011/120397 A1, JP 2012 215137 A, CN 105 370 454 A and WO 2017/075390 A1.
The object of the present invention is that of efficiently overcoming the aforesaid drawback, at the same time using simple and inexpensive means.
In view of achieving the aforesaid object, the present invention relates to a system for recirculating blow-by gases having all the characteristics indicated in claim 1. In a preferred embodiment, the saw-like toothed profile includes a plurality of pointed tooth protruding axially and defining between them a plurality of compartments with pointed bottoms.
Thanks to the aforesaid characteristics, the recirculation system according to the present invention is able to easily and efficiently overcome the risk of ice formations, which would undermine the correct functioning of the system.
The irregular profile of the annular end surface of the aforesaid tubular element, through which the clean blow-by gases recirculate into the intake duct of the engine, creates discontinuities in the ice formations, which cause these formations to weaken, with the result that they are drastically limited or even completely blocked.
Another advantage of the aforesaid irregular profile of the annular end surface of the tubular element for recirculating the blow-by gases lies in the fact that this uneven profile creates turbulence in the flows of air and blow-by gases, resulting in improved mixing of these flows. Moreover, the irregular profile allows improvement of the field of fluid-dynamic motion within the ducts, thus increasing the depression in the confluence area of the blow-by gases into the intake air flow, resulting in an increase in the suction effect to which the blow-by gases are subjected.
The shape (height and width), the number, and the position of the teeth of the aforesaid irregular profile are chosen according to each specific application. The same applies to the diameter, the height, and the inclination of the portion of said tubular element or snorkel that protrudes inside the main duct portion in which the intake air flows.
Studies and investigations by the Applicant have shown that it is preferable, in any case, that the height/width ratio of each tooth of the irregular profile is between 0.2 and 5, and that the ratio between the width of each tooth of the aforesaid irregular profile and the inner diameter of the aforesaid tubular element or snorkel is between 5 and 50. It is also preferable that the height of each tooth of the irregular profile is between 0.1 and 10 mm.
Further characteristics and advantages of the invention will become apparent from the description that follows with reference to the attached drawings, provided purely by way of non-limiting example, wherein:
With reference to
An intake manifold 5 is associated with the cylinder head 2, which receives the air flow passing through an air intake duct 6, and feeds this air flow to the cylinders of the engine (not shown in the drawing). The cylinder head 2 is also associated with an exhaust manifold 7, through which the exhaust gases leaving the engine cylinders are conveyed into a duct 8 for the exhaust gases, which conducts the gases to an exhaust gas treatment device (not visible in the drawing). In the case of the illustrated example, a turbine 9 is provided in the exhaust gas duct 8 for driving a supercharger compressor 10, interposed in the intake duct 6, upstream of the intake manifold 5. Of course, these components are illustrated herein with reference to a particular embodiment, since it is evident that the invention is applicable to any type of engine, even non-supercharged engines. Still according to a conventional technique, in the air intake duct 6, upstream of the compressor 10, an air filter 11 and a butterfly valve 12 are interposed. The specific configuration of these components, as well as the butterfly valve control system, are not described or illustrated here, since they can be produced in any known way.
Still with reference to
The outlet 13B of the clean blow-by gases is connected to the air intake duct 6 by means of a blow-by gas recirculation duct 14, which flows into the intake duct 6 by means of a T-connector member, indicated in its entirety by 15.
With reference to
The axis 16 of the tubular element or snorkel 15B is generally essentially transverse to the axis 17 of the main duct portion 15A. In the illustrated example, the axes 16, 17 are orthogonal to each other and reciprocally incident. However, it is also possible to provide the axes 16, 17 wherein they form an angle other than 90°. Still in the case of the example illustrated in
In
One important characteristic of the present invention lies in the fact that the aforesaid annular end surface 18 of the tubular element or snorkel 15B has an irregular profile, which in the illustrated embodiment is formed of a plurality of pointed teeth 19, projecting axially and defining between them compartments with pointed bottoms 20.
As discussed above, the irregular profile defined by the teeth 19 creates an anti-ice function, as it completely or partially prevents the formation of ice caused by the freezing of water particles contained in the air flow A and/or the flow of blow-by gases B at low temperatures. The teeth 19 create discontinuities in the ice formations, thus weakening these formations or preventing them altogether.
Another advantage deriving from the irregular profile of the annular end surface 18 lies in the fact that it gives rise to a turbulence in the flows A and B of air and blow-by gases, which improves the mixing of these flows while, at the same time, optimizing the field of fluid-dynamic motion so as to increase the local depression and the resulting suction effect to which the blow-by gases are subjected.
The height H and the width W (
Studies and investigations of the Applicant have shown that it is particularly preferable if the H/W ratio between the height and width of each tooth 19 is between 0.2 and 5, and that the ratio between the inner diameter D of the tubular element or snorkel 15B and the width W of each tooth 19 is between 5 and 50. Furthermore, the height H of each tooth 19 is preferably between 0.1 and 10 mm.
The constructive design of the T-connector member 15 can, of course, be made in any preferred manner. In particular, the tubular element or snorkel 15B can be formed of a separate body with respect to the main duct portion 15A, which is inserted through an opening formed in the wall of the main duct portion and welded to said wall. Alternatively, the two elements 15A, 15B can also be produced in a single body. Additionally, the T-connector member can be made by a separate element with respect to other components or can be integrated, as a whole or in part, into other components, for example, in an inlet connection of the compressor 10.
More generally, without prejudice to the principle of the invention, the details of construction and the embodiments may vary widely with respect to those described and illustrated, without departing from the scope of the present invention, as defined in the attached claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 17177057.1 | Jun 2017 | EP | regional |
