Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
  • F02M35/10—Air intakes; Induction systems
  • F02M35/10006—Air intakes; Induction systems characterised by the position of elements of the air intake system in direction of the air intake flow, i.e. between ambient air inlet and supply to the combustion chamber
  • F02M35/10019—Means upstream of the fuel injection system, carburettor or plenum chamber
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
  • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
  • F02M35/10—Air intakes; Induction systems
  • F02M35/10209—Fluid connections to the air intake system; their arrangement of pipes, valves or the like
  • F02M35/10222—Exhaust gas recirculation [EGR]; Positive crankcase ventilation [PCV]; Additional air admission, lubricant or fuel vapour admission

Definitions

• the present invention relates to the technical sector of diesel engines provided with a recirculation system of the exhaust gases, and more in particular relates to an air suction and exhaust gases recirculation system for a diesel engine as defined in the preamble of claim 1.
• Exhaust Gas Recirculation is one of the systems used in engines, in particular in diesel engines, to limit the emission of Nitrogen Oxides (NOx) caused by the oxidation of atmospheric nitrogen as a result of the high temperatures and pressures present inside the combustion chamber during functioning.
• NOx Nitrogen Oxides
• EGR valve which by varying the cross-section of transit of the exhaust gases recirculation duct regulates the quantity of exhaust gas recirculated.
• the actuation of the EGR valve is generally controlled by the engine electronic control unit according to specific functioning algorithms.
• a first expedient of the prior art to increase the quantity in mass of the exhaust gases recirculated consists of using an air-water heat exchanger on the EGR branch between the hot branch (exhaust) and cold branch (suction) , which is suitable for cooling the exhaust gas before the quantity of exhaust gas to be recirculated is supplied to the suction system of the engine.
• a second expedient of the prior art to increase the quantity of exhaust gas recirculated consists typically of providing, in addition to the aforementioned heat exchanger, an electronically controlled throttle valve which may be placed either in the exhaust system to regulate the back-pressure to the exhaust of the engine, or in the suction system, to regulate the negative suction pressure of the engine.
• throttle valve has however some drawbacks.
• the use of the throttle valve entails a greater cost and a greater complexity of the exhaust gases recirculation system, in that it requires for example a dedicated HW resource (driver) inside the control unit needed to control it and a dedicated SW module for the actuation and diagnosis of the throttle valve actuator, including a "fault reaction" strategy.
• malfunctioning of the valve may prejudice the correct quantity of recirculated gas required and consequently lead to non-compliance with the limits imposed as regards the emission of Nitrogen Oxides or, in the worst case, to the engine stopping.
• the throttle valve is an electro-mechanical actuator, it may in fact suffer from electric problems, (disconnection of wires, incorrect power supply voltage, problems on the position sensor, problems of the electric motor etc, ) and mechanical problems ( wear, seizing, sticking etc) .
• One purpose of the present invention is to make available a suction and exhaust gases recirculation system for a diesel engine which is able to overcome or at least partially reduce the drawbacks discussed above with reference to the prior art.
• one purpose of the present invention is to make available a suction and exhaust gases recirculation system for a diesel engine which is simpler than the systems of the prior art and which at the same time which gives a general performance in relation to the emissions of Nitrogen Oxide and to fuel consumption which is substantially unvaried or in any case comparable to that of the aforesaid prior systems.
• the present invention also relates to a diesel engine and a motorised vehicle as defined respectively in the appended claims 15 and 16.
• FIG. 1 is a plan view showing a partial schematic and high level representation of an air suction and exhaust gases recirculation system according to a currently preferred embodiment, said system being shown coupled to a cylinder and an exhaust manifold of a diesel engine ;
• FIG. 2 shows a graphic representation of the functioning of a regulation device of the system in Fig.l depending on some of the functioning parameters of the engine ;
• FIG. 3 is perspective view showing a diesel engine according to a currently preferred embodiment in which the air suction and exhaust gases recirculation system in Fig.l is implemented;
• FIG. 4 is partial perspective view showing an air suction and exhaust gases recirculation system according to a currently preferred embodiment which is supplied in the diesel engine in Fig.3;
• FIG. 5 is a perspective view in which some components of the system in Figure 4 are shown and in which some element are shown in cross-section;
• - Fig.6 is a front plan view of an element in Fig.4; and - Fig. 7 is a cross-section view of the element in Fig.6.
• FIG. 1 shows a high level schematic view partially representing an air suction and exhaust gases recirculation system for a diesel engine according to a currently preferred embodiment.
• the system 1, 2 comprises a suction system 1 and an exhaust gas recirculation system 2 or EGR (Exhaust Gas Recirculation) system 2.
• the suction system 1 comprises a suction duct 3, 4 provided to channel air aspirated from the atmosphere to at least one cylinder 5 of the aforesaid diesel engine.
• the suction duct includes an intake manifold 3 and a suction line 4 connected to said intake manifold 3.
• the suction line 4 is positioned upstream of the intake manifold 3.
• the suction line 4 is partially represented in Fig.l in that the other elements of a suction line of a diesel engine, as well as the suction system of such a motor, such as for example the air filter or the so-called “snorkel” that is to say the connection tube used to suck the air from the more sheltered areas, are widely known to the person skilled in the sector.
• the exhaust gas recirculation system 2 is provided to introduce back into the suction duct 3, 4 a part of the exhaust gases coming from an exhaust pipe 6 of the aforesaid engine.
• the exhaust pipe 6 is partially represented in Fig.l in that the other elements of an exhaust pipe of a diesel engine are widely known to the person skilled in the sector.
• Fig.l shows only the exhaust manifold 7 of the exhaust pipe 6.
• the recirculation system 2 comprises a recirculation duct of the exhaust gases 8, 9, 10 which is fitted with an output gate door 11 for the aforesaid part of the exhaust gas to be recirculated.
• the output gate 11 is suitable for communicating with the suction duct.
• the recirculation system 2 comprises a flow regulation device of the exhaust gases 12, or valve 12, which is provided along the recirculation duct 8, 9, 10 to regulate the aforesaid part or quantity of exhaust gases to be introduced back into the suction duct 3, 4.
• the regulation device 12 comprises an EGR valve 12.
• the recirculation duct 8, 9, 10 is operatively positioned between the exhaust manifold 7 and the suction manifold 3.
• the recirculation duct 8, 9, 10 comprises an initial tract 8 fitted with an input gate 13 for the exhaust gases to be recirculated, communicating with the exhaust manifold 7, an intermediate tract 9 and an end tract 10 including the aforesaid output gate 11.
• a heat exchanger 14 is preferably provided between the tracts 8 and 9, in a manner in itself known having the function of cooling the exhaust gases to be introduced back into the intake manifold 3.
• the valve 12 instead is positioned between the tracts 9 and 10 of the recirculation duct.
• the valve 12 is operatively connected to a control unit (not shown) , preferably the control unit of the diesel engine, which is provided to control the valve 12.
• control unit is suitable for controlling the movement of an obturator device 15 so as to regulate the opening/closing of the output cross-section 16 of the tract 9 of the recirculation duct.
• valve 12 is shown in a completely closed valve configuration in which the flow of exhaust gas to be recirculated introduced back into the suction duct is nil.
• the valve 12 assumes a completely open valve configuration in which the flow of exhaust gas to be recirculated introduced back into the suction duct is maximum.
• FIG. 2 a graphic representation of a preferred example of functioning of the valve 12 is shown depending on some of the functioning parameters of the engine.
• the numbers from 0 to 100 indicated on the ordinates show the degree of aperture of the valve 12 in percentage terms.
• degree of aperture is understood as the ratio between the area of the cross-section 16 not obstructed by the obturator 15 and the entire area of the cross-section 16.
• the value 0 on the vertical axis corresponds to the completely closed valve configuration while the value 100 on the ordinates corresponds to the completely open valve configuration.
• control unit is set or programmed to control the valve 12 so as to keep the valve 12 in the completely open valve configuration or in the substantially completely open valve configuration (the "substantially completely open valve configuration" being understood as a valve with a degree of aperture generally comprised between 80% and 100%, and more preferably comprised between 90% and 100%, in which the flow of exhaust gas is substantially maximum) in a range of revs of the crankshaft comprised between approximately 600 revs/min and approximately 1100 revs/min with a quantity of fuel injected of 2mm 3 /stroke/cylinder and approximately 20 mmVstroke/cylinder .
• control unit is set or programmed to control the valve 12 so as to keep the valve 12 in the completely open valve configuration or in the substantially completely open valve configuration in a range of revs of the crankshaft comprised between approximately 600 revs/min and approximately 1500 revs/min and with a quantity of fuel injected comprised between 1 mmVstroke/cylinder and approximately 24 mm 3 /stroke/cylinder .
• control unit is set or programmed to control the valve 12 so as to keep the valve 12 in the completely open valve configuration or in the substantially completely open valve configuration in a range of revs of the crankshaft comprised between approximately 600 revs/min and approximately 3600 revs /min with a quantity of fuel injected comprised between 3mm 3 /stroke/cylinder and 6mm 3 /stroke/cylinder .
• control unit is set or programmed to control the valve 12 so as to keep the valve 12 in the completely open valve configuration in a range of revs of the crankshaft comprised between approximately 600 revs/min and approximately 3600 revs /min with a quantity of fuel injected comprised between 1 mmVstroke/cylinder and approximately 12 mm 3 /stroke/cylinder .
• valve 12 for example with reference to Fig.2 advantageously permits the reduction to a minimum, compared to the systems of the prior art discussed above in which the valve does not remain completely open in the functioning ranges of the engine indicated above with reference to the valve 12, of the transitory effects caused by the inertia of the regulation system with the positive effects of a greater reintroduction of recirculated gases and a consequent greater reduction of pollutant emissions .
• the intake manifold 3 comprises an input cross-section 17 (section A-A) to permit the input into the intake manifold of the air coming from the suction line 4.
• the suction duct 3, 4 comprises a duct cross-section 18 situated upstream or at most, at the output gate 11 of the exhaust gases to be recirculated.
• the input cross-section 17 has a first fluid transit area and the duct cross-section 18 has a second fluid transit area.
• the second fluid transit area is an invariant and reduced area compared to the first fluid transit area. In other words the numerical value of the second fluid transit area is less than the numerical value of the first fluid transit area.
• the expression “invariant area” is understood to mean an area having a predefined geometry and dimensions invariant over time and which in particular is not associated to any device suitable for selectively modifying such area, such as for example and not limited to a throttle valve. It is to be noted moreover that the expressions “upstream” and “downstream” used to describe elements of a duct are understood to refer to the main direction of the flow of fluid in the duct in question.
• the expressions "upstream” and “downstream” refer respectively to the direction of the flow of aspirated air indicated by the arrow Al in the case of the suction duct 3, 4, to the direction of the flow of exhaust gases indicated by the arrow Bl in the case of the exhaust pipe 7, and to the direction of the flow of exhaust gases to be recirculated indicated by the arrow CI in the case of the recirculation duct 8, 9, 10.
• cross-section referred to a duct is normally used to indicate a through cross-section of a fluid which is arranged transversally and more in particular orthogonally to the longitudinal axis of the duct or to the main direction of the flow of fluid in the duct .
• the duct cross-section 18 may be situated in any part of the suction duct as long as upstream of the output gate 11 of the exhaust gases to be recirculated.
• the duct cross-section 18 may be situated in the suction line 4 in a part of such line situated further upstream than in the representation in Fig.l.
• the output gate 11 for the exhaust gases to be recirculated may also be positioned on the suction line 4, rather than on the intake manifold 3, as long as the duct cross- section 18 is still situated upstream or at most, at the output gate 11.
• the duct cross-section 18 may be situated in the intake manifold 3 downstream of the input cross-section 17 (but upstream of the output gate 11) .
• the duct cross-section 18 may be also situated so as to be exactly adjacent to the input cross-section 17 of the intake manifold.
• the duct cross-section 18 is situated in an input portion 19 of the intake manifold 3 or in an output portion 20 of the suction line 4.
• the input portion 19 comprises the input cross-section 17.
• the output portion 20 is connected, preferably in a detachable manner, to the input portion 19.
• the output portion 20 may also be connected in a non-detachable manner to the input portion 19, for example welding the portions 19, 20 to each other.
• the input portion 19 generally corresponds to a portion of the intake manifold comprised between the input cross-section 17 and the output gate door 11 of the exhaust gases to be recirculated.
• the input portion 19 has a length, measured along the suction duct axis, which is comprised between several millimetres and little more than ten centimetres, for example comprised between approximately 2-3mm and approximately 14 cm.
• the output portion 20 is an end portion of the suction line 4.
• the output portion has a length, measured along the suction duct axis, which is comprised between Omm and approximately 400mm, and preferably comprised between 0 and 200mm.
• FIG.3 shows a diesel engine according to a preferred embodiment which has been generally indicated by reference numeral 30.
• the air suction and exhaust gases recirculation system 1, 2 shown in Fig.l has been implemented in the engine 30.
• the engine 30 is preferably an aspirated diesel engine, and more preferably an aspirated diesel engine with a so- called "common rail" system.
• the engine 30 is a two cylinder engine.
• teachings of the present invention may clearly be applied to an engine having any number of cylinders.
• the engine 30 has an engine size of approximately 1000 cubic centimetres and a nominal power comprised between approximately 15 kW and 19.5 kW at a speed of rotation of the crankshaft equal to 3600 revs/min.
• the engine 30 is suitable to be installed on a motorised vehicle such as for example a light transport vehicle having for example a maximum load of 1.5 tons such as for example a vehicle sold as a light transport vehicle with a maximum load of 1.5 tons.
• FIG. 4 shows two output cross-sections 32, 33 of the intake manifold 3 provided to permit the entrance of a mixture of air and recirculated exhaust gases, each in a respective cylinder of the engine 30.
• Figure 5 shows a part of the system 1, 2 in Fig.4 shown partially in cross-section.
• Fig. 5 shows the manifold 3, the valve 12, and the tract 10 of the recirculation duct of the exhaust gases.
• Fig.5 both a part 31, 34 of the suction duct 4 and a part of the intake manifold 3 at the input section 17 are shown in cross-section.
• the part 31, 34 is part of the output portion 20 of the suction line 4.
• the suction duct comprises a choke member 34 or orifice plate 34.
• the orifice plate 34 is provided with an orifice 35 which defines a choke of the suction duct 3, 4.
• the orifice 35 defines the second fluid transit area of the duct cross-section 18.
• the orifice plate 34 is provided to determine an increase of the predefined pressure drop in the suction duct (compared to the case in which no orifice plate is present in the suction duct) in general upstream of the output gate 11 for the exhaust gases to be recirculated, so as to determine an increase of the predefined negative pressure in the suction duct, and more preferably in the intake manifold 3, suitable to increase the flow of exhaust gases to be recirculated in the suction duct.
• the aforesaid increase is then achieved, increasing the pressure difference between the output gate 11 and the input gate 13 of the recirculation duct 8, 9, 10.
• the duct cross-section 18 is conveniently arranged substantially adjacent to the input cross- section 17 of the intake manifold.
• the orifice plate 34 may however be positioned so that the duct cross-section 18 is situated at a distance from the output cross-section 32 of the intake manifold (Fig.l and Fig.4) which is preferably comprised between 110mm and 540mm. It is to be observed that such distance is measured along the axis of the suction duct.
• the output cross-section 32 is the output cross-section of the intake manifold 3 associated to the cylinder of the engine 30 which is closest to the duct cross-section 18.
• the orifice plate 34 is coupled, for example welded, to one end of the aforesaid member 31.
• the member 31 is preferably an adaptor tube 31 to which a flexible hose (not shown) of the suction line is destined to be fitted, such as a flexible rubber hose, which is preferably connected to the air filter of the engine 30.
• the adaptor tube 31 comprises a constant cross-section tract upstream of the orifice plate 34.
• Figures 6 and 7 respectively show a front view and a transversal cross-section view of the orifice plate 34.
• the orifice 35 comprises a constant cross- section orifice tract 37 and an increasing cross-section orifice tract from upstream to downstream 38.
• the increasing cross-section orifice tract 38 has an end cross-section of maximum area 39 and the percentage ratio between said maximum area and the area of a cross-section of said constant cross-section orifice tract 37 is comprised between 125% and 130%.
• the constant cross-section tract 37 is a cylindrical tract and the increasing cross-section tract 38 is a truncated cone tract.
• the cylindrical tract 37 has a nominal diameter of 31mm while the cross-section of maximum area has a nominal diameter of 35mm.
• the percentage ratio between the area of the constant cross-section orifice tract 37 and the area of the cross-section of the constant cross-section tract of adaptor tube 31 is preferably comprised between 25% and 45% and more preferably comprised between 30% and 35%. It is to be observed that in general the aforesaid orifice 35 preferably has a circular cross-section. However such cross-section may in general be of another shape, for example elliptical, at most square. Moreover such cross- section may also be asymmetrical or off centre in relation to the axis of the suction duct as long as the ratios between the areas mentioned above preferably remain .
• a "Venturi tube" portion of the suction duct could be used as long as the output gate 11 is positioned at the duct cross-section 18 of the aforementioned Venturi tube.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Exhaust-Gas Circulating Devices (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=48145601

Family Applications (1)

Country Status (7)

Family Cites Families (7)

• 2013
  • 2013-02-22 IT IT000103A patent/ITRM20130103A1/it unknown
• 2014
  • 2014-02-11 ES ES14703610.7T patent/ES2670527T3/es active Active
  • 2014-02-11 EP EP14703610.7A patent/EP2959154B1/de active Active
  • 2014-02-11 WO PCT/EP2014/052651 patent/WO2014128026A1/en active Application Filing
  • 2014-02-11 CN CN201480010192.2A patent/CN105074190B/zh not_active Expired - Fee Related
  • 2014-02-20 TW TW103105595A patent/TWI606176B/zh not_active IP Right Cessation
  • 2014-02-24 AR ARP140100569A patent/AR094865A1/es active IP Right Grant

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