WO2024047465A1

WO2024047465A1 - A head for internal combustion engine

Info

Publication number: WO2024047465A1
Application number: PCT/IB2023/058342
Authority: WO
Inventors: Luigi BUOVOLO
Original assignee: Stellantis Europe S.P.A.
Priority date: 2022-08-29
Filing date: 2023-08-22
Publication date: 2024-03-07

Abstract

There is described a head (1) for internal combustion engine, comprising: at least one intake conduit (2) at least one exhaust conduit (3), wherein a combination of at least one intake conduit (2) and at least one exhaust conduit (3) is associable to a corresponding cylinder of an internal combustion engine, an exhaust gas recirculation path (4) extending from an inlet port (EGR_IN) to an outlet port (ECL IN), and configured to be supplied with exhaust gas expelled through said one or more exhaust conduits (3), an exhaust gas recirculation valve (V8) arranged along said exhaust gas recirculation path, and configured to enable and disable (8, 9, 10, 11) a flow of exhaust gas through said exhaust gas recirculation path ( 4 ), wherein the exhaust gas recirculation path (4) extends within said head (1) from said inlet port (EGR_IN) to said outlet port (ECL_IN).

Description

"A head for internal combustion engine"

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TEXT OF THE DESCRIPTION

Field of the Invention

The present invention relates to internal combustion engines . More speci fically, the invention was developed with reference to a high pressure exhaust gas recirculation circuit , commonly known with the acronym HP-EGR (High Pressure EGR) . In the following, for the sake of brevity, sometimes the use will be made of the phrase "HP-EGR circuit" or of the phrase "high pressure EGR circuit" in order to denote said system .

Prior Art

Figures 1 , 2A and 2B (which are identical , and wherein 2A has some components removed in order to show elements which otherwise would not be visible ) annexed to the present description show a head H for an internal combustion engine , having an HP-EGR circuit according to the prior art . The head H comprises a plurality of intake conduits INC, a plurality of exhaust conduits EXC and a high pressure , HP, EGR circuit . In a fashion known in itsel f , one or more conduits INC and one or more conduits EXC are grouped in such a way as to implement a functional association with respective cylinders of the internal combustion engine . In the example of Figure 1 , the association envisages a pair of conduits INC and a pair of conduits EXC for each cylinder . Within head H, in a position between conduits INC and EXC and partially surrounding them, a cooling j acket CD is provided, wherein a fluid flows for cooling the internal combustion engine . Reference HP globally denotes the high pressure EGR circuit , which extends through various components .

An exhaust mani fold EXM i s moreover installed at the outlet sections of the conduits EXC on the side wall of the head H, so as to receive the exhaust gas generated during the operation of the internal combustion engine . The exhaust mani fold EXM comprises a spill section S , which defines a first section of circuit HP, ending with a port EGR_OUT ( the partial passage section of the port is identi fied with the area covered with parallel lines and having a contour in dashed lines ) , through which the exhaust gas spilled from mani fold EDM is sent to an inlet port EGR_IN of an EGR valve unit denoted by reference EVU . The passage of the exhaust gas may take place at a position totally external to head H ( and in this case the ports EGR_OUT and EGR_IN are connected directly) , or it may take place , as in the Figure , at an angle section of head H within a flow channel FC .

The unit EVU is a component which is physically separated from the head H, and it is coupled thereto by means of screws . The unit EVU comprises an actuator EAC which controls a movable apparatus , comprising a stem VS and a valve member V, so as to enable (with or without partiali zation) or to disable the transit of the flow of exhaust gas entering from port EGR_IN towards the inlet into a heat exchanger ECL . Figure 2 globally shows the internal volumes within unit EVU, together with part of the cooling j acket CJ for better clarity . The path defined by arrows with uni formly filled tips identi fies the flow of the exhaust gas spilled from the mani fold EXM so as to recirculate them to the engine intake , while the path defined by arrows with non- filled tips identi fies the flow of cooling liquid circulating in the j acket CJ and operating in a heat exchange relationship with the unit EVU .

As will be observed in Figure 2 , the flow of exhaust gas enters unit EVU through port EGR_IN, transits through the section whereat valve member V is located ( or stops at said section when actuator ACT controls the closing of the passage ) and enters a substantially U-shaped path which flows to a port MV_IN leading to a partialization valve MV. The partialization valve MV is configured in such a way as to decrease, if necessary, the flow of recirculated exhaust gas (i.e., of the exhaust gas which has already passed the valve member) into the heat exchanger ECL, and comprises a flap-shaped movable element MVF rotatable around an axis YE. The end positions of the flap-shaped movable element MVF are respectively shown with a continuous line and with a dotted line.

The first position (continuous line) corresponds to a condition without partialization: all the flow of the exhaust gas which has traversed the valve member V is sent to a port RGI, wherefrom the flow of recirculated gas flows in a conduit towards an inlet port ECL_IN of the exchanger ECL. Inside such exchanger, the flow of exhaust gas follows a further U-shaped path (which is preferably defined by a tube bundle) to reach an outlet port ECL_OUT, wherefrom the exhaust gas is sent to the engine intake (upstream the inlet port of a turbocharger unit, if present) .

The second position (in dotted lines) corresponds to a condition of full partialization: all the flow of the exhaust gas which has traversed valve member V is prevented from transiting through exchanger ECL, and is sent - without being cooled - integrally to the intake of the engine (upstream the inlet port of a turbocharger unit, if present) through a port G_OUT . A part of the port G_OUT may moreover coincide with the port ECL_OUT, as can be seen in Figure 2B, therefore substantially acting as a manifold of the cooled and uncooled fractions of the recirculated exhaust gas flow.

As regards the path of the cooling fluid in the jacket CJ, at the portion of head H wherein the unit EVU is installed, the path branches into two parts, thus defining a first flow entering exchanger ECL through a port C_IN, so as to contact the tube bundle wherein the exhaust gas transits and so as to exit from a port C_OUT , and a second flow which enters the body of the unit EVU for cooling the same , and then returns to the main circuit through a port CJR ( Figure 2A) . The unit EVU moreover comprises an auxiliary inlet port VC_IN and an auxiliary outlet port VC_OUT for the cooling liquid, so as to improve the cooling of stem VS , which may otherwise be subj ected to cogging due to the high temperature of the exhaust gas .

The technical problems of the solutions of the known art , whereof Figures 1 and 2 represent generally valid implementations , are immediately evident from the description provided in the foregoing . The flow paths , both of the exhaust gas and o f the cooling fluid, are relatively complex and transit across several j unctions between physical ly distinct components . Moreover , the current structure of the unit EVU demands the implementation of cooling circuits in the interior thereof , as well as a supply and a discharge speci fic for cooling the stem VS , which further complicate the system .

Obj ect of the Invention

The invention aims at solving the technical problems outlined in the foregoing . Speci fically, the invention aims at simpli fying the structure of the high pressure EGR circuit without af fecting, possibly even improving, the performance thereof with respect to the prior art .

Summary of the Invention

The obj ect of the invention is achieved by means of a head for an internal combustion engine having the features set forth in the claims that follow, which form an integral part of the technical disclosure provided herein with reference to the invention .

Brief Description of the Figures

The invention will now be described with reference to the annexed Figures , which are provided by way of non-limiting example only, wherein :

- Figure 1 , already commented in the foregoing, is a perspective , partially sectional view of a head for an internal combustion engine according to the known art , equipped with a high pressure EGR circuit ,

Figures 2A, 2B, already commented in the foregoing, are perspective non-sectional views of volumes for the passage of fluids in the engine of Figure 1 ,

- Figure 3 is a perspective , partially sectional view of a head for an internal combustion engine according to the invention,

- Figure 4 is a perspective view s imilar to Figure 2 , but referring to the invention .

Detailed Description

Reference number 1 in Figure 3 generally denotes a head for an internal combustion engine according to the invention .

In various embodiments , the head 1 comprises at least one intake conduit 2 and at least one exhaust conduit 3 , wherein - in a way per se known - a combination of at least one intake conduit 2 and at least one exhaust conduit 3 can be associated to a corresponding cylinder of an internal combustion engine . In the embodiment of Figure 3 , the association envisages a pair of conduits 2 and a pair of conduits 3 ( the latter conduits being united at the exit ) for each cylinder of the internal combustion engine .

The head 1 moreover comprises an exhaust gas recirculation path 4 , which extends from an inlet port EGR_IN - which is always represented as a surface having a dashed outline on the section plane of head 1 and filled with oblique lines - to an outlet port ECL_IN ( the same references are used as in the representations of the known art in Figure 1 and Figure 2 ; therefore , the meaning and the functional features thereof are unvaried) , and which is configured for being supplied with exhaust gas expelled through the one or more exhaust conduits 3 . The path 4 comprises an exhaust gas recirculation valve 5 (EGR valve ) which is arranged along the exhaust gas recirculation path 4 and which is configured to enable and disable a flow of exhaust gas through the path 4 . More speci fically, the path 4 comprises an upstream section 6 and a downstream section 7 which are functionally separated by valve 5 , the upstream section extending from the port EGR_IN to the valve 5 and the downstream section extending from the valve 5 to the port ECL_IN . According to the invention, the exhaust gas recirculation path 4 extends within head 1 from the inlet port EGR_IN to the outlet port ECL_IN .

Referring to Figure 3 , the exhaust gas recirculation valve 5 comprises a valve member 8 configured to cooperate with a valve seat 9 (which functionally divides the upstream section 6 from the downstream section 7 ) in order to enable and disable the exhaust gas flow through path 4 , and a valve stem 10 connected to valve member 8 and being controllable by means of an exhaust gas recirculation valve actuator 11 . The valve stem 10 penetrates , at least partially, within the exhaust gas recirculation path 4 , as can be seen in Figure 3 . More speci fically, the valve stem 10 is arranged axially movable along an axis VX within a bushing 12 fixed to the head 1 , so as to define a wall section of path 4 by closing an installation opening on the head 1 , while the actuator 11 is fixed externally to the bushing 12 . The assembly of actuator 11 , stem 10 and valve member 8 (possibly including bushing 12) defines an exhaust gas recirculation valve V8, i.e., an EGR valve. The stem 10 and the valve member 8 define a movable apparatus of the valve V8, which is controlled by means of actuator 11.

Referring to Figure 4 (and partially to Figure 3) the head 1 comprises a cooling jacket 13, which is configured for the transit of a cooling fluid flow through the head. The cooling jacket 13 comprises an internal volume (which can be seen in Figure 4) in heat exchange relationship with the recirculation path 4 and with the volumes of the at least one intake conduit 2 and/or the at least one exhaust conduit 3. To this end, the jacket 13 extends in a position between the intake conduits 2 and the exhaust conduits 3. Preferably, at least the exhaust conduits are in contact with the cooling liquid which flows within jacket 13, due to the higher temperatures.

According to an advantageous aspect of the invention, the internal volume of the cooling jacket 13 surrounds, at least partially, the exhaust gas recirculation path 4. Specifically, Figure 4 shows a preferred embodiment, wherein the volume of jacket 13 extends arch-wise around the portion of path 4 where the bushing 12 is installed, so as to cool the valve stem 10 by conduction through the bushing 12, and surmounts the internal volume of said exhaust gas recirculation path, i.e. the jacket is arranged above the volume of path 4. The surmount of the volume of the flow path 4 is in any case independent from the arch-shaped extension around the seat of bushing 12. In other embodiments, a reversed configuration may be envisaged, wherein the jacket 13 is arranged below the volume of path 4.

The junction between the outlets of the exhaust conduits 3 and the path 4 is implemented by means of an exhaust mani fold 14 , which includes one or more inlet ports 15 (which are always represented as surfaces having a contour in dashed lines on the section plane of head 1 , and a surface covered with oblique lines ) to receive the exhaust gas expelled through the one or more outlet ports 3 , and a spill port EGR_OUT in fluid communication with the inlet port EGR_IN of the exhaust gas recirculation path . In the embodiment shown in Figures 3 and 4 , the exhaust mani fold 14 is a component separate from head 1 , and it is fixed thereto by means of screws . It will be observed that , unlike in head H, the conduit FC is not necessary, because path 4 , including the movable apparatus of valve V8 , is provided within the head from the inlet EGR_IN to the outlet ECL_IN, and therefore it is suf ficient to establish a fluid communication between the mani fold 15 , speci fically the port EGR_OUT , and the port EGR_IN .

However, embodiments are envisaged wherein the exhaust mani fold 14 is provided - in a generally known fashion - in one piece with head 1 . In such embodiments , the cooling j acket 13 generally extends to contact the exhaust mani fold as well , because the latter is made of the same material of head 1 , which also needs cooling .

Moreover, according to an advantageous aspect of the invention (which is valid irrespective of the configuration, in one piece or separated, of the exhaust mani fold 14 ) , the head 1 may integrate the valve MV which has already been described with reference to Figure 2B : the port ECL_IN becomes port MV_IN, and directly downstream the latter the seat is provided for the movable flap/ throttle element MVF and the forked path for the exhaust gas flow, with a branch directed towards the inlet of the heat exchanger ECL and a branch bypassing the exchanger ECL (port G_OUT ) . Advantageously, it is possible to implement the port G_OUT in such a way as to incorporate the port ECL_OUT , in order to unite both recirculated exhaust gas flows - the cooled flow and the uncooled flow - before they are sent to the intake of the engine . Such a partiali zation valve MV therefore comprises an inlet MV_IN corresponding to the outlet port ECL_IN of the exhaust gas recirculation path, a first outlet (which functionally corresponds to the port ECL_IN in Figure 4 ) and a second outlet (which functionally corresponds to the port G_OUT ) , and it comprises the valve element MVF, which is movable between a first operating position, wherein a flow transit is enabled from the inlet to the first outlet , with occlusion of the second outlet , a second operating position, wherein a flow transit is enabled from the inlet to the second outlet , with occlusion of the first outlet, and at least one intermediate position between the first operating position and the second operating position .

When the engine is operating, the exhaust gas generated by combustion is sent to conduits 3 , and they are expelled therefrom into the exhaust mani fold 14 . A part of the exhaust gas flow is spilled and, through the interface between the ports EGR_OUT and EGR_IN, it is sent into path 4 , flowing through the upstream section 6 , then through the downstream section 7 , i f the movable apparatus of valve V8 is controlled in such a way as to separate valve member 8 from seat 9 . In a way known in itsel f , by means of valve V8 it is possible to bring about an occlusion of the port of the downstream section 6 , by driving the valve member 8 to contact seat 9 and thereby preventing the transit of exhaust gas in path 4 , or else to bring about various degrees of partiali zation by controlling the movable apparatus in such a way as to vary the width of the passage lumen between the valve member 8 and the seat 9 , therefore varying the exhaust gas flow through path 4 from the upstream to the downstream section.

As in the instance of Figure 2, in Figure 4 (and partially in Figure 3) the path defined by arrows with dark tips identifies the flow of the exhaust gas spilled from manifold 14 and sent to path 4 for recirculation to the engine intake, while the path defined by arrows with white tips identifies the flow of cooling liquid circulating in the jacket 13 and operating in a heat exchange relationship, i.a., with valve V8.

The exhaust gas flow which follows path 4 is sent to port ECL_IN, wherefrom it enters a heat exchanger similar to exchanger ECL, wherein the exhaust gases are cooled by means of heat exchange with a second fluid, typically the same cooling fluid which flows in jacket 13. In this regard, referring to Figure 4, the cooling fluid circulating in the jacket 13 flows in a volume which surrounds, as much as possible, the path 4 and the seat wherein bushing 12 is installed, so as to cool the portion of head 1 wherein path 4 is arranged and the movable apparatus, without the need for auxiliary cooling ports. The cooling fluid then returns to the main cooling circuit of the engine, while the flow of recirculated and cooled exhaust gas is sent to the engine intake (into the intake manifold downstream of the throttle valve, or upstream of the intake of the turbocharger unit, if present) .

If valve MV is present, and if it is integrally provided in the head 1, the flow entering port MV_IN (previously ECL_IN) is treated as described in the foregoing, i.e., according to needs, it is partly (or wholly) sent to cooling in heat exchanger ECL, and correspondingly partly (or wholly) sent to the bypass of exchanger ECL, without being cooled.

The person skilled in the art will appreciate that head 1 of fers a solution to all technical problems mentioned in the foregoing . Speci fically, manufacturing head 1 is definitely simpler and more economical than manufacturing the head H of the known art . This is clear in a comparison between Figures 2 and 4 : the former clearly shows the need of providing a high number of casting cores for the definition of the internal volumes ( the internal volumes shown correspond to the shape of the cores used during the casting manufacturing process of head H) , while a head 1 having the same features ( i . e . , the same tools to be used for casting) only needs a core for the cooling j acket 13 and one single core for the path 4 and for the valve V8 ; the latter core , anyway, has a much simpler shape than the cores needed for the unit EVU . Moreover, the possibility is given to integrate the path 4 and a substantial part of valve V8 within head 1 , thereby reducing cost and overall dimensions . Moreover, valve V8 does not require any auxiliary cooling circuit for cooling stem 10 , and the head 1 is generally better adapted to be functionally integrated with the exhaust mani fold 14 , especially when the latter is made in one piece with head 1 .

Last , but not least , although the embodiments described herein mainly refer to a high pressure EGR circuit , the head 1 equally lends itsel f to the implementation of a low pressure EGR circuit , while keeping the same advantages ( e . g . , on spark ignition atmospheric engines , i . e . , engines without turbocharging) .

Of course , the implementation details and the embodiments may amply vary with respect to what has been described and illustrated, without departing from the scope of the present invention, as defined by the annexed claims .

Claims

1. A head (1) for internal combustion engine comprising :

- at least one inlet conduit (2) at least one exhaust conduit (3) , wherein a combination of at least one intake conduit (2) and at least one exhaust conduit (3) is associable to a corresponding cylinder of an internal combustion engine,

- an exhaust gas recirculation path (4) extending from an inlet port (EGR_IN) to an outlet port (ECL_IN) and configured to be supplied with exhaust gas expelled through said one or more exhaust conduits (3) ,

- an exhaust gas recirculation valve (V8) arranged along said exhaust gas recirculation path and configured to enable and disable (8, 9, 10, 11) a flow of exhaust gas through said exhaust gas recirculation path (4) , wherein said exhaust gas recirculation path (4) extends within said head (1) from said inlet port (EGR_IN) to said outlet port (ECL_IN) .

2. The head (1) according to claim 1, further comprising a cooling jacket (13) configured for the circulation of a cooling fluid flow, said cooling jacket (13) having an internal volume in heat exchange relationship with said exhaust gas recirculation path (4) and with the volumes of said at least one intake conduit (2) and/or said at least one exhaust conduit (3) .

3. The head (1) according to claim 2, wherein the internal volume of the cooling jacket (13) at least partially surrounds said at least one exhaust gas recirculation path (4) .

4. The head (1) according to claim 3, wherein a portion of the internal volume of said cooling jacket (13) surmounts an internal volume of said exhaust gas recirculation path (4) .

5. The head (1) according to claim 3 or claim 4, wherein said exhaust gas recirculation valve (V8) comprises a valve member (8) configured to cooperate with a valve seat (9) to enable and disable a flow of exhaust gas through said exhaust gas recirculation path (4) and a valve stem (10) connected to said valve member (8) and controllable by means of an exhaust gas recirculation valve actuator (11) , the valve stem (10) penetrating at least partially within the exhaust gas recirculation path (4) .

6. The head (1) according to claim 5, wherein the valve stem (10) is arranged axially movable within a bushing (12) fixed to said head (1) , the bushing (12) being at least partially surrounded by the internal volume of said cooling jacket (13) for a cooling of said valve stem (10) .

7. The head (1) according to claim 1, further comprising an exhaust manifold (14) including one or more inlet ports (14) for receiving exhaust gases expelled through said one or more exhaust conduits (3) and a spill port (EGR_OUT) in fluid communication with the inlet port (EGR_IN) of the exhaust gas recirculation path ( 4 ) .

8. Head (1) according to claim 7, wherein the exhaust manifold (14) is, alternatively:

- a separate component from said head (1) and is fixed thereto, - made in one piece with said head ( 1 ) .

9. Head ( 1 ) according to any one of the preceding claims , wherein a partialisation valve (MV) is arranged at an outlet port (ECL_IN, MV_IN) of the exhaust gas recirculation path, the partialisation valve compri sing an inlet corresponding to the outlet port (ECL_IN, MV_IN) of the exhaust gas recirculation path, a first outlet (ECL_IN) and a second outlet ( G_OUT ) and further comprising a valve element movable between a first operating position in which a flow transit from the inlet to the first outlet is enabled, with occlusion of the second outlet , a second operating position in which a flow transit from the inlet to the second outlet is enabled, with occlusion of the first outlet , and at least one intermediate position between said first operating position and said second operating position .

10 . An internal combustion engine comprising a head ( 10 ) according to any one of the preceding claims .