GB2473279A

GB2473279A - Intake system for a charged internal combustion engine comprising a baffle

Info

Publication number: GB2473279A
Application number: GB0915645A
Authority: GB
Inventors: Arndt Roman Doehler; Bernhard Marin
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2009-09-08
Filing date: 2009-09-08
Publication date: 2011-03-09
Anticipated expiration: 2029-09-08
Also published as: GB0915645D0; GB2473279B

Abstract

An intake system 1 of a charged internal combustion engine comprising an intake manifold 7 in communication with at least one combustion chamber 2, where the combustion chamber comprises an intake port 6 and an exhaust port 11, a fuel injection valve 14 with a fuel injection tip 15 within the intake manifold and a baffle 16 in the intake manifold or the intake port to direct the gas or fuel. The baffle may be positioned downstream or upstream from the fuel injection valve tip to produce a reduction in pre-ignition events in the cylinder. The baffle may also be positioned radially at an inner side of the intake manifold, cylinder head or intake port. The baffle can be fixed or is adjustable to occupy a variable cross-sectional area of the intake manifold or intake port, where the baffle may be rotatable. Preferably the baffle comprises a plate with at least one through hole.

Description

Intake system of an internal conibustion engine, internal corn-bustion engine and vehicle comprising the intake system The application relates to an intake system of an internal combustion engine, an internal combustion engine and a vehicle comprising the intake system.

An internal combustion engine, for example of an automotive vehicle, typically includes a plurality of variable volume combustion chambers each provided by a cylinder including a cylinder head and a piston reciprocating within the cylinder.

The engine also includes an intake manifold through which gas such as fresh air can enter the combustion chambers. The entry of the air into the combustion chamber and the exit of the ex-haust gases out of the combustion chamber are controlled by means of at least one intake valve and an exhaust valve, re-spectively.

Fuel can be directly injected into the combustion chamber by one or more fuel injection valves positioned in the cylinder head. Alternatively, the fuel may be injected into the intake manifold or intake port of the cylinder head.

In all arrangements of the fuel injection valve, it is desir- able to properly control the combustion of the air-fuel mix- ture in the combustion chamber so as to increase the perform-ance of the engine and reduce emissions. Furthermore, it is also desirable to prevent, or at least reduce, uncontrolled combustion phenomena such as engine knock and pre-ignition since this uncontrolled combustion can produce extremely high pressures within the cylinder which may cause damage to the piston. The term pre-ignition describes an uncontrolled corn-bustion defined by the start of combustion before the ignition point. Pre-ignition can lead to knocking combustion cycles or to cycles without knock, but, nevertheless, with high peak pressures.

DE 10 2006 006102 Al discloses an intake system for a turbo-charged direct injection engine. Each cylinder of the engine is provided with two intake ports which each include an ad-justable baffle in order to produce a turbulent gas flow. The turbulent gas from the two intake ports is mixed with fuel which is injected directly into the combustion chamber in or-der to provide an improved air-fuel mixture and improve the combustion process.

However, it is also desirable to improve the combustion behav-iour in charged internal combustion engines, such as turbocharged and supercharged internal combustion engines in which the fuel injection valve is positioned in the intake manifold.

The present application provides an intake system of a charged internal combustion engine which comprises an intake manifold, a fuel injection valve and a baffle to direct gas and fuel.

The intake manifold is in flow communication with at least one variable volume combustion chamber defined by a piston recip-rocating within a cylinder comprising a cylinder head. The cylinder further comprises an intake port through which gas and fuel can enter the combustion chamber from the intake manifold and an exhaust port through which exhaust gases can exit the combustion chamber. The fuel injection valve has a fuel injection tip which is arranged in the intake manifold or the intake port of the cylinder head. The baffle is arranged in the intake manifold or in the intake port of the cylinder head and is arranged so as to direct the flow of gas or gas and fuel.

The application provides two embodiments of an intake system of a charged internal combustion engine which differ in the position of the baffle. In the first embodiment, the baffle is arranged in the intake manifold and in a second embodiment the baffle is arranged in the intake port of the cylinder head.

The baffle may be arranged upstream or downstream of the tip of the fuel injection valve or at the same position as the tip of the fuel injection valve, i.e. neither upstream nor down-stream.

If the baffle is arranged upstream of the tip of the fuel in-jection valve, the baffle is arranged so as to direct the flow of charged gas and, due to the flow of the gas also, indi-rectly, the fuel, from the intake manifold into the cylinder.

The gas may solely comprise fresh air or may comprise a mix- ture of fresh air and exhaust gas recirculated from the ex-haust system. If the baffle is arranged downstream of the tip of the fuel injection valve, the baffle is arranged so as to direct the flow of a mixture of the charged gas and fuel from the intake manifold into the cylinder.

The position of the baffle in the intake manifold or in the intake port of the cylinder head leads to a reduction in un-controlled combustion events in the variable volume combustion chamber. Therefore, the maximum pressure arising in the vari-able volume combustion chamber due to uncontrolled combustion may also be reduced. By reducing the peak pressure and/or the number of uncontrolled combustion events, damage to the cylin- der and, in particular, the piston can be avoided. Further-more, these effects can be achieved by the use of the baffle without the additional use of additional sensors, actuators and control systems. The intake system of the present applica- tion is simpler to produce and more cost-effective than sys-tems with these additional features.

The reduction or even elimination of uncontrolled combustion phenomena leads to an increase in the lifetime of the engine and can lead to an improvement in the performance of the en- gine. Furthermore, by reducing the cyclical combustion varia-tion, the peak loading of the exhaust treatment system can be reduced.

In a further embodiment, each cylinder comprises a single in-take port.

In an embodiment, the position of the baffle is optimised in relation to its distance from the tip of the fuel injection valve in order to produce desirable effects. The baffle may be positioned upstream or downstream from the fuel injection valve at a distance selected to produce a significant reduc- tion of 50% or even more in the pre-ignition rate of combus-tion in the cylinder over that measured for the same intake system without the baffle. In this context, downstream refers to the general direction of flow of gas and fuel through the intake manifold.

In an embodiment, the baffle is positioned 0 to 3 centimetres upstream of the tip of the fuel injection valve or, prefera-bly, upstream of the tip of the fuel injection valve and within a distance of 3 centimetres upstream of the tip of the fuel injection valve.

In an embodiment, the baffle is positioned 0 to 3 centimetres downstream of the tip of the fuel injection valve or, prefera-bly, downstream of the tip of the fuel injection valve and within a distance of 3 centimetres downstream of the tip of the fuel injection valve.

In an embodiment, the baffle is positioned directly underneath the tip of the fuel injection valve.

The baffle may be positioned radially at an inner side of the intake manifold or at the inner side of the intake port of the cylinder head. The baffle may be fixedly attached to the inner side of the intake manifold or the cylinder head by, for exam-ple, welding. The baffle may be made of a plastic, metal or alloy such as steel.

The first embodiment, the baffle is fixed. In this sense, fixed is used to describe a baffle whose cross-sectional area is fixed. The baffle itself is solid and inflexible.

In an alternative embodiment, the baffle is adjustable so as to be able to occupy a variable cross-sectional area of the intake manifold or intake port of the cylinder head. The baf-fle may be rotatable about an axis and may have the form of a

flap, for example.

The cross-sectional area of the fixed baffle may be selected so that it occupies from 20% to 60% of the cross-sectional area of the intake manifold. In case of an adjustable baffle, the size of the baffle in combination with its adjustable range can be selected so that it can occupy between 25 to 60% of the cross-sectional area of the intake manifold depending upon how it is adjusted.

Both types of baffle, that is a fixed baffle and an adjustable baffle, may have the form of a plate whose thickness extends parallel or at a defined angle in the range 00 to 90° to the general direction of flow of gas and fuel through the intake manifold or the intake port of the cylinder head. In a further embodiment, the baffle has the form of a ramp which is so formed that it occupies an increased portion of the cross- section area of the intake manifold or intake port of the cyl-inder head in the general direction of flow of gas and fuel.

In a further embodiment, the baffle further comprises at least one through-hole. The through-hole may be arranged to redirect the flow of gas and/or fuel in the intake manifold. The through-holes may be arranged to extend generally parallel to the general direction of flow of the gas and fuel through the intake manifold.

The invention also provides an internal combustion engine com-prising the intake system of one of the previous embodiments and a charger arranged to deliver charged gas to the intake manifold. The charger may be an exhaust gas driven turbo- charger or may be a mechanically driven supercharger. The com- bustion engine may be a spark ignition engine or a self igrii- tion engine such as a HCCI (Homogeneous Charge Compression Ig-nition) engine.

The application also provides a vehicle comprising the inter- nal combustion engine and a supercharger or a turbocharger ac-cording to one of the embodiments described above.

The baffle is arranged in the intake manifold or in the intake port of the cylinder head so as to influence the movement of the gas/fuel mixture with the aim of achieving one or more of the following effects: narrowing the cross-sectional area of the flow, increasing the flow rate, the swirl rate and tumble level of the incoming air or air/fuel mixture flow; decreasing the droplet size of the fuel introduced into the intake manifold and combustion chamber; homogenizing the air/fuel distribution particularly in the combustion chamber; reducing cyclical variations of combustion; avoiding or at least reducing uncontrolled combustion and ran-domly occurring combustion peak pressures such as megaknock and pre-ignition, and reducing the concentration, in particular, of the carbon diox-ide, carbon monoxide and hydrocarbons in the exhaust gases.

B

Furthermore, by avoiding uncontrolled combustion and reducing undesirably high combustion peak pressures, it is possible to increase the performance level of the charged engine. This ef-fect enables downsizing, that is a reduction in the effective fuel consumption. By controlling the combustion peak pres-sures, the components carrying the engine can be made lighter and/or the lifetime of the engine can be increased.

By minimising or at least reducing the cyclical combustion variation, the load peak is on the exhaust treatment system can be reduced so that meeting future stricter exhaust emis-sions norms may become easier. By avoiding the use of active diagnosis components (European onboard diagnosis/onboard diag-nosis components), sensors for displaying the situation can be avoided saving additional product and development costs. The robustness of the whole system is increased.

Embodiments will now be described with reference to the accom-panying drawings.

Figure la illustrates a schematic view of an intake system of a charged internal combustion engine according to a first embodiment, Figure lb illustrates a schematic view of an intake system of a charged internal combustion engine according to a second embodiment, Figure 2a illustrates a baffle positioned in the intake mani-fold of the intake system of figure 1, Figure 2billustrates a baffle according to a third embodiment which may be positioned in the intake manifold of figure 1, Figure 3 illustrates a baffle according to a fourth embodi-ment which may be positioned in the intake manifold of figure 1, Figure 4 illustrates a graph showing a reduction in the preignition rate achieved by use of the baffle ac-cording to the application, Figure 5 illustrates a graph showing the reduction of soot achieved by use of the baffle according to the ap-plication, Figure 6 illustrates a graph showing the improved combustion stability achieved by use of the baffle according to the application, Figure 7 illustrates the improved spray preparation achieved by use of the baffle according to the application, Figure 8 illustrates an intake system of a charged internal combustion engine comprising a baffle according to a fifth embodiment, and Figure 9 illustrates the intake system of a charged internal combustion engine comprising a baffle according to a sixth embodiment.

Figure 1a illustrates a schematic view of an intake system 1 of a charged internal combustion engine according to a first embodiment.

Figure la illustrates one of a plurality of variable volume combustion chambers 2 of the internal combustion engine, each of which is defined by a piston 3 reciprocating within a cyl- inder 4 comprising a cylinder head 5. The variable volume com- bustion chamber 2 is connected by an intake port 6 to an in-take manifold 7 through which gas, indicated with arrow 8, and fuel, indicated with arrow 9, can enter the combustion chamber 2. In further non-illustrated embodiments, two or more intake ports are provided.

The variable volume combustion chamber 2 further comprises an intake valve 10 to close and open the intake port 6 and an ex-haust port 11 and outtake valve 12 through which exhaust gases can exit the combustion chamber 2 as is indicated with the ar-row 13.

The intake system further comprises a fuel injection valve 14 including a fuel injection tip 15 which is arranged in the in-take manifold 7. In further non-illustrated embodiments, the fuel injection tip is arranged so as to inject fuel into the intake port of the cylinder head.

Fresh air or a mixture of fresh air and recirculated exhaust gas is supplied by a non-illustrated charger, which in this embodiment is an exhaust driven turbocharger, to the intake manifold 7. Fuel is injected into the intake manifold 7 and into the charged gas flow by the fuel injection valve 14 which is also arranged in the intake manifold 7. The air and fuel mixture flows into the combustion chamber 2 where it is ig-nited by spark plug 25.

According to the present application, the intake system 1 fur- ther includes a baffle 16 which, in this embodiment, is ar-ranged in the intake manifold 7 and further arranged to direct the gas from the charger and fuel from the fuel injection tip into the combustion chamber 2. The baffle 16 is arranged slightly upstream of the fuel injection valve tip 15. In one embodiment, the baffle is arranged around 1 cm upstream of the fuel injection valve tip 15.

The baffle 16 has the form of a solid inflexible plate which is fixedly attached to an inner surface 17 of the intake mani-fold 7. The baffle 16 is arranged at a preselected distance upstream of the fuel injection valve tip 15. Both the area of the baffle 16, the consequent reduction in the cross-sectional area of the intake manifold 7 at the position of the baffle 16 and the distance of the baffle 16 from the fuel injection valve tip 15 are selected so as to produce one or more of the following technical effects: narrowing the cross-sectional area of the flow, increasing the flow velocity, the swirl rate and tumble level of the incoming air/fuel mixture flow, decreasing the droplet size of the fuel introduced into the intake manifold and combustion chamber, homogenizing the air/fuel distribution particularly in the combustion chamber, reducing cyclical variations of combus-tion, avoiding or at least reducing uncontrolled combustion and randomly occurring combustion peak pressures such as megaknock and pre-ignition, and reducing the concentration, in particular, of the carbon dioxide, carbon monoxide and/or hy-drocarbons in the exhaust gases.

Figure lb illustrates a schematic view of an intake system 1 of a charged internal combustion engine according to a second embodiment. The intake system of the second embodiment differs from that of the first embodiment illustrated in Figure la in the position of the baffle 16 relative to the fuel injection valve tip 15. In the second embodiment, the baffle 16 is posi-tioned downstream of the fuel injection valve tip 15 rather than upstream as in the first embodiment. In this particular embodiment, the baffle 16 is positioned in the intake port 6 rather than in the intake manifold 7.

Figure 2a illustrates a plan view along the line A-A of the baffle 16 of figure lb. Figure 2a illustrates that the baffle 16 has a generally rectangular form and extends from the lower surface 17 towards the centre of the intake port 6 of the cyl-inder head 5 and also extends across the entire width of the intake port 6 in the lower portion. In this embodiment, the baffle 16 occupies a significant portion, for example, ap-proximately 40%, of the cross-sectional area of the intake port 6 of the cylinder head 5 at this position. The baffle 16 of the first embodiment may also be arranged in the intake manifold 7 as is illustrated in Figure la.

Figure 2b illustrates a baffle 16' according to a third em-bodiment. The baffle 16' comprises two separate pieces 26, 27 which each have a generally rectangular form. Each piece 26, 27 extends inwardly from two opposing side walls 19, 20 of the intake manifold 7 in a common plane so that each piece 26, 27 extends from the lower inner surface to the upper inner sur- face of the intake manifold 7 in the two opposing edge re-gions. The two pieces 26, 27 may be arranged symmetrically about the centre line of the intake manifold. The baffle 16' of the third embodiment may also be positioned in the intake port of the cylinder head.

Figure 3 illustrates a baffle 18 according to a fourth embodi- ment. The baffle 18 also has the form of a generally rectangu-lar plate which is positioned in the intake manifold 7 and fits between the two opposing side walls 19, 20 and lower sur-face 17 of the intake manifold 7 as in the first embodiment.

The baffle 18 according to the fourth embodiment differs form the baffle 16 of first embodiment in that it further comprises a through-hole 21 positioned in approximately the centre of the baffle 18 and extending generally parallel with the flow direction of the gas and fuel through the intake manifold 7.

The through-hole 21 serves to redirect the flow of the gas and fuel.

In further non-illustrated embodiments, the baffle includes two or more through-holes which may or may not be uniformly distributed across the baffle and which may or may not have the same diameters. The through-hole or through-holes are not necessarily circular but can have other shapes in plan view such as square, rectangular and hexagonal.

The baffle 18 and the non-illustrated baffles may be arranged upstream or downstream or in line, i.e. neither upstream nor downstream, of the fuel injection valve tip. The baffle 18 and the non-illustrated baffles may be arranged in either the in-take manifold or in the intake port of the cylinder head.

Some technical effects of the baffle according to the present application are illustrated in the graphs of figures 4 to 7.

Figure 4 illustrates a graph of the reduction in the pre-ignition rate as a function of the air/fuel ratio X (lambda) for two types of fuel, RON 98 and RON 91, with and without the baffle according to the application. This graph illustrates that the pre-ignition rate is reduced by use of the baffle ac-cording to the application. Reductions of over 50% and even over 90% can be achieved.

Figure 5 illustrates a graph of the reduction of soot (filter smoke number FSN) as a function of the air/fuel ratio (lambda) for fuel type RON 98. Figure 5 illustrates that the amount of soot in the emissions can be reduced by around 80% or even more by use of the baffle according to the applica-tion.

Figure 6 illustrates a graph of the coefficient of covariation (COV) of the in-cylinder pressure as a function of the igni-tion point measured from the Top Dead Centre of the combustion cycle. Figure 6 illustrates that the combustion stability can be improved, as illustrated by a reduction in the COV value, by use of the baffle according to the application.

Figure 7 illustrates views of an intake port of the cylinder head without a baffle according to the present application and an intake port of the cylinder head with a baffle according to the present application. Figure 7 illustrates an air/fuel mix- ture entering the intake port of the cylinder head and illus- trates that the droplet size of the fuel can be reduced lead- ing to improved spray preparation by use of the baffle accord-ing to the application.

Figure 8 illustrates an intake system 1' of a charged internal engine according to a fifth embodiment. The intake system 1' also comprises a baffle 22. The intake system 1' of the fifth embodiment differs from the intake system 1 of the embodiments illustrated in figure la and figure lb in the position of the baffle 22. In the fifth embodiment, the baffle 22 is posi- tioned at the cylinder head 5 and, in particular, is posi-tioned so as to occupy a portion of the intake port 6 of the cylinder head. The baffle 22 may have the form of a partial ring which extends from a portion of an inner side of the in-take port 6 of the cylinder head 5.

Figure 9 illustrates the intake system 1'' of a charged inter-nal combustion according to a sixth embodiment. The intake system 1'' also includes a baffle 23 positioned in the intake manifold 7. The baffle 23 differs from the baffle 16 of figure la and figure lb in that its position is adjustable. In par-ticular, the baffle 23 is rotatable about an axis 24 which lies generally perpendicular to the flow of the gas and fuel.

By rotating the baffle 23 about this axis 24, the baffle 23 is able to occupy differing proportions of the cross-sectional area of the intake manifold 7.

At one extreme, the baffle 23 may lie flush with the inner surface 17 of the intake manifold 7 and occupy little or no of the cross-sectional area intake manifold 7. At the other ex-treme, the baffle 23 may be rotated about the axis 24 so that it rises into the intake manifold 7 and may occupy up to 50% or even a higher proportion of the cross-sectional area of the intake manifold 7.