WO2007116160A1

WO2007116160A1 - Cylinder head comprising a water core having a degassing part and method of producing such a cylinder head

Info

Publication number: WO2007116160A1
Application number: PCT/FR2007/050893
Authority: WO
Inventors: Olivier Beisbardt; Bernard Camilleri
Original assignee: Renault S.A.S
Priority date: 2006-04-06
Filing date: 2007-03-08
Publication date: 2007-10-18
Also published as: FR2899501A1; FR2899501B1; EP2002098A1

Abstract

The present invention relates to a cylinder head for an internal-combustion engine comprising a water core and method of producing such a cylinder head comprising the steps of making a mould pattern (7) to form a water core for the cylinder head (10), this water core pattern comprising a main part (8, 9) and a protruding part (6); positioning the pattern (7) of the cylinder head water core on a cylinder head wall (20) core, the protruding part resting on part of the cylinder head wall core; then, after closure of the cylinder head wall core, injecting metal into the cylinder head wall core; and destroying the water core pattern and evacuating the material constituting the water core pattern, the protruding part of the water core pattern generating a protruding part corresponding to the water core. The invention provides a step of fitting a degassing system (51, 52) connected to the corresponding protruding part of the water core.

Description

HEAD COMPRISING A WATER CORE PROVIDED WITH A DEGASSING PART AND PROCESS FOR PRODUCING SAID HEAD

TECHNICAL FIELD TO WHICH THE INVENTION RELATES The present invention generally relates to cylinder heads of internal combustion engines.

It relates more particularly to an internal combustion engine cylinder head comprising a water core and a method of manufacturing such a cylinder head. TECHNOLOGICAL BACKGROUND

Currently, engines have a very high power density. Their designs are becoming ever closer to the strength limits of materials, so even the slightest failure of the cooling system of these engines can have serious consequences. In particular, in such engines, the central zone of the cylinder head located near the combustion chamber and exhaust ducts can reach or exceed 230 ° C, which requires a powerful cooling system.

Cooling systems generally used include a water core consisting of channels for circulating coolant in the cylinder head to cool the areas of the cylinder head with great thermal stress and around the elements interacting with the cylinder head such as the valves and the cylinder head. fuel injector.

There are two types of water core, on the one hand, the so-called longitudinal water cores and, on the other hand, those with transverse circulation, with respect to the axis of the cylinder head. The axis of the cylinder head is defined as being the axis passing through the centers of the heads of the cylinders. A longitudinal circulation water core is configured to circulate the coolant in the cylinder head in a direction substantially parallel to the cylinder head axis, and a cross-flow water core is configured to circulate the coolant. in the cylinder head in a direction substantially transverse to the axis of the cylinder head.

A first problem stems from the fact that air bubbles remain stuck in the upper part of the water core of the cylinder head. In the absence of evacuation of these bubbles, that is to say degassing, the walls of the parts of the cylinder head in which these air bubbles accumulate are not cooled by the coolant.

For cooling systems using a water core with longitudinal circulation, there is provided a water outlet housing associated with the cylinder head located at a sufficiently high position to be able to recover the air bubbles and proceed to degassing the core. 'water. But, for cooling systems using a cross-flow water core, the coolant, coming from the cylinder block located below the cylinder head, passes through the water core transversely to the axis of the cylinder head and return to the cylinder block. The water outlet housing is then associated with the cylinder block and is located at a position too low to recover the air bubbles and allow the degassing of the water core.

To solve this first problem, it is known to pierce the cylinder head in the upper part of the water core, that is to say where will accumulate air bubbles. However, this solution requires an additional drilling step which increases the manufacturing costs of the cylinder head. In addition, the drilling operation is complicated because it must preserve the integrity of the different parts of the cylinder head and engine elements around the water core. A second problem is related to the realization of the water core of the cylinder head. The water core is obtained by molding by producing a positive circulation channels of the cylinder head. This positive water core then comes to rely on a core of walls of the cylinder head to generate the cylinder head with the corresponding water core. However, for reasons of space in the cylinder head around the water core to be made, the upper part of the positive water core can be connected only on one side to the lower part of the positive core of water. water. The upper part of the positive water core then rests on one side in the vacuum which makes the positive of the water core unstable. This instability may lead to a bad arrangement of the positive water core in the core walls and thus a bad configuration of the water core generated in the cylinder head.

OBJECT OF THE INVENTION

The object of the present invention is to facilitate the degassing of the water core of the cylinder head and to improve the accuracy of the configuration of this water core in the cylinder head. For this purpose, it is proposed according to the invention a method of manufacturing a cylinder head of an internal combustion engine which comprises the following steps:

- producing a mold positive for forming a water core of the cylinder head, the positive water core comprising a main portion and a protruding portion,

- Positive positioning of the water core of the cylinder head on a core wall of the cylinder head, the protruding portion being supported on a portion of the core wall of the cylinder head,

- after closing the core of the cylinder head walls, injecting metal into the core of the walls of the cylinder head,

- Destruction of the positive water core and evacuation of the material constituting the positive water core, the protruding portion of the positive water core generating a corresponding protruding portion of the water core,

- Establishment of a degassing system associated with the corresponding protruding portion of the water core.

The protuberant portion of the positive water core which rests on a portion of the core wall of the cylinder head allows, on the one hand, to ensure the stability of the positive water core in the core wall of the cylinder head. The water core generated by the metal injection, then the destruction of the positive water core, then has the desired configuration in the cylinder head. On the other hand, the protruding portion of the positive water core generates, after destruction, a chamber having an opening in the cylinder head that allows to set up a degassing system. The protuberant portion thus serves as a bearing or support of the positive water core and allows, once the water core is formed, the evacuation of air bubbles through the chamber that this protruding portion generates.

Thus, the method of manufacturing the cylinder head facilitates the degassing of the water core of the cylinder head and improve the accuracy of the configuration of the water core in the cylinder head.

According to a first advantageous characteristic of the invention, said positive is produced such that said protruding part is the highest part of the positive of the water core, in a configuration of this positive corresponding to a normal configuration of use of the engine.

The high position of the protruding portion of the positive allows, during the production of the cylinder head and after destruction of the positive water core, to generate a chamber that is the highest part of the water core. The air bubbles accumulate in this room and can be evacuated through the degassing system.

According to another advantageous characteristic of the invention, the evacuation of material constituting the positive of the water core is carried out by the corresponding protruding part of the water core.

The protruding part thus makes it possible, not only to stabilize the positive of the water core and to set up a simplified degassing system in the cylinder head, but also to generate a chamber having an opening opening out of the cylinder head through which the material constituting the positive of the water core can be evacuated.

The invention also relates to an internal combustion engine cylinder head water positive for molding such a cylinder head, having a main portion and a protruding bearing portion, wherein the protuberant portion of the positive is the portion the highest of the positive, in a positive configuration corresponding to a normal configuration of use of the engine.

When molding the yoke, the protruding portion of the positive water core may be supported on a portion of the core wall of the cylinder head to provide stability of the positive water core in the wall core of the cylinder head. cylinder head. In addition, the high position of the protruding portion of the positive core can be used to set up in the corresponding part of the water core of the cylinder head a degassing system.

The invention finally relates to an internal combustion engine cylinder head, within which is formed a water core having a main portion and a protruding portion, wherein a degassing system is associated with said protruding portion.

The protruding portion of the water core is a chamber that allows to set up a degassing system. In addition, the protruding portion of the water core is formed from a corresponding protruding solid portion of the positive water core that can be used in the manufacture of the positive water core support portion yoke. on the wall core of the cylinder head. Thus, the cylinder head according to the invention makes it possible to facilitate the degassing of the water core of the cylinder head and to improve the accuracy of the configuration of this water core in the cylinder head.

According to a first advantageous characteristic of the cylinder head according to the invention, the protruding part of the water core is the highest part of the water core, in a normal configuration of use of the engine.

Thanks to the high position of the protruding part of the water core, the air bubbles accumulate in the chamber formed by this protruding part and can be evacuated through the degassing system. According to another advantageous characteristic of the invention, the main part of the water core comprising a lower part and an upper part, the lower part is connected to a first portion of the upper part and the protruding part is connected to a second portion. from the top of the water core. The lower, upper, and protruding portions of the water core originate from the corresponding lower, upper, and protruding portions of the positive water core. Thus, when producing the cylinder head by molding, the protruding portion associated with the upper part of the positive water core ensures the stability of the upper part of the water core in the core of walls of the cylinder head . The upper part of the positive water core has several bearing portions, direct and indirect, which allow to accurately position this upper part, and therefore the positive whole water core, in the core of walls of the cylinder head .

According to another advantageous characteristic of the invention, the first portion and the second portion of the upper portion of the water core are substantially distributed on either side of the center of the upper part of the water core.

Thus, still during molding, the upper part of the positive water core being supported on diametrically opposite portions, the seat of this upper part of the positive water core, and therefore the positive water core whole, in the wall core of the cylinder head is improved.

According to another advantageous characteristic of the invention, the degassing system comprises a closure cap of the protruding portion corresponding water core and a degassing screw implanted in the closure cap.

Thus, the degassing system can be easily set up thanks to the chamber generated by the corresponding protruding portion of the water core and avoids drilling the upper part of the water core.

According to another advantageous characteristic of the invention, the degassing screw is located in the upper part of the closure plug.

Thus, the implantation of the degassing screw in the upper part of the closure plug makes it possible to evacuate the air bubbles that accumulate in the upper part of the chamber formed by the protruding portion of the water core.

According to another advantageous characteristic of the invention, the lower part of the cylinder head constituting the upper part of several aligned cylinders of the engine to which the cylinder head belongs, the water core of the cylinder head is arranged in such a way that the circulation of water in the water core is made in a direction generally transverse to the direction of the axis passing through the centers of the cylinders.

Thanks to the method according to the invention, the transverse circulation type water cores benefit from a simplified degassing system and a more precise configuration of the water core in the cylinder head. DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The following description with reference to the accompanying drawings of an embodiment, given by way of non-limiting example, will make it clear what the invention consists of and how it can be achieved.

In the accompanying drawings: - Figure 1 is an overall perspective view of the positive of a water core of a cylinder head;

FIG. 2 is an overall perspective view of the positive of the water core of FIG. 1 from another angle;

- Figure 3 is an overall perspective view of the positive water core positioned in a core wall of the cylinder head;

- Figure 4 is a view of a portion of the cylinder head equipped with a degassing system.

Figures 1 to 4 illustrate the implementation of a method of manufacturing a cylinder head 10 of an internal combustion engine of a motor vehicle. This manufacturing method comprises firstly a step of producing a positive 7 of a water core of the cylinder head 10 which is intended to be positioned in a core of walls 20 of the cylinder head 10. When it is referred to the positive 7 of the water core, it is a solid element which comprises solid parts, here in resinated sand, whereas when one refers to the water core itself, it is a hollow volume consisting of circulation channels of the cylinder head 10 in which is intended to circulate the coolant, here water, and which have been generated by the solid parts of the positive 7 of the nucleus of water as described below. For ease of understanding and reading, the parts of the water core positive and the water core channels that correspond to these parts have the same reference.

The positive 7 of the water core is made by means of a mold of resinated sand and has a main part and a protruding part 6. The main part of the positive 7 of the water core comprises a lower part 9 and a upper part 8.

The lower portion 9 of the positive 7 of the water core of the cylinder head has inlet portions 91, 92, 93. In particular, the inlet portion 91 is extended by a lower peripheral portion 97 and the inlet portion 93 is extended by a lower peripheral portion 99 opposite, while the inlet portion 92 is extended by a lower central portion 98 to be positioned between exhaust valves 12,13 (see Figure 3) and close to A fuel injector 15. The lower peripheral portions 97, 99 extend and join to form a lower peripheral portion 96 for surrounding intake valves 11, 14 (see Figure 3). Two outlet portions 94, 95 opposite the inlet portions 91, 92, 93 relative to the center of the lower portion of the positive 7 of the water core are connected to the lower peripheral portion 96.

The lower central portion 98 is then extended by a central connecting portion 89, between the lower portion 9 and the upper portion 8 of the positive water core, opening on an upper central portion 72 surrounding the fuel injector 15 and passing between the exhaust valves 12, 13. This upper central portion 72 is extended by a portion 74 intended to be positioned between the intake valves 1 1, 14. On either side of the upper central portion 72 and part 74 of extension, there are provided peripheral portions 71, 73, connected to connecting portions 87, 88 between the lower portion 9 and the upper portion 8 of the positive 7 of the water core.

The protruding portion 6 is connected to the upper portion 8 of the positive 7 of the water core. More precisely, as represented in FIGS. 1 and 2, the lower part 9 carries a first portion P1 of the upper part 8 and the protruding part 6 is connected to a second portion P2 of the upper part 8 of the water core so as to to ensure the seating of the positive 7 of the water core in the wall core 20 of the cylinder head 10. Here, the protruding portion 6 is connected to a second portion P2 located as far as possible from the first portion P1, taking into account of the bulk around the upper part 8 of the water core. Thus, in FIG. 1, the protruding portion 6 is located angularly at 90 ° to the first portion P1 relative to the mean center of the upper portion 8 of the positive 7 water core. Preferably, in the absence of congestion problem in the cylinder head 10 around the water core, the first portion P1 and the second portion P2 of the upper portion 8 of the positive water core are substantially distributed on both sides. other from the center of the upper part 8 of the positive 7 of the water core to allow optimizing the seat of the upper part 8 of the positive 7 of the water core in the wall core 20 of the cylinder head 10.

The protruding portion 6 is of substantially cylindrical shape. In the drawing of Figure 1, we note that this protruding part 6 forms a bend. This elbow is made here so that the protruding portion 6 can bypass the various motor elements integrated in the cylinder head 10. Of course, in the absence of congestion problem in the cylinder head 10, the protruding portion 6 may be straight and / or of any shape.

Once the positive 7 of the water core of the cylinder head 10 is produced, this positive 7 of the water core is placed in position on or in the wall core 20 (or mold) of the cylinder head 10 (see FIG. 3). The lower part of the cylinder head 10 constitutes the heads of several cylinders aligned along an axis which is called the axis of the cylinder head. The lower central portion 98 is intended to be oriented substantially transversely to the axis of the yoke to be molded in the wall core 20. A portion 61 of the protruding portion 6 is supported on a portion of the wall core 20 of the cylinder head 10, and opens out of the wall core 20 of the cylinder head 10. Alternatively, the protruding portion 6 can be positioned in such a way that it is flush with this core of walls 20. The protruding part 6 is associated with the main part of the positive 7 of the water core and positioned in the wall core 20 of the yoke 10 so as to generate, during the destruction of the positive of the water core, a chamber which is, in a normal configuration of use of the vehicle, the highest hollow part of the water core. A normal configuration of use of the vehicle here corresponds to a position of the vehicle resting on a horizontal surface. For such a configuration, the engine, and thus the cylinder head, is mounted in the vehicle by being inclined by about 8 degrees relative to the horizontal surface, so that the chamber generated by the protruding part 6 is the hollow part of the vehicle. higher of the water core. The wall core 20 of the cylinder head 10 is then closed and metal is injected into the wall core 20 of the cylinder head 10.

Once the metal has taken the desired shape in the wall core 20 of the yoke 10, the positive 7 of the water core is destroyed, which generates the water core described above. In particular, the protruding portion 6 of the positive water core generates a chamber, also called corresponding protruding part of the water core, which has an opening opening out of the cylinder head. Then the material is removed, here resinated sand constituting the positive 7 of the water core. This evacuation is here performed by the chamber generated by the protruding portion 6 of the positive water core. The resinated sand parts of the positive 7 of the water core thus leave room in the cylinder head 10 for coolant circulation channels which form the water core of the cylinder head. In particular, the walls of the chamber generated by the protruding portion 6 of the positive water core are defined by the metal that has been injected around the protruding portion 6. In addition, the wall generated from the upper portion of the core The water forms a roof with a slope of the order of 8 degrees in the normal detailed configuration of use above.

Finally, as shown in FIG. 4, a degassing system 51, 52 associated with the chamber generated by said part is set up. protruding 6. The degassing system 51, 52 here comprises a closure cap 51 of the chamber generated by said protruding portion 6 and a degassing screw 52 implanted in the closure cap 51. The degassing screw 52 is located in the upper part of the closure cap 51. It is also possible to machine the opening of the chamber generated by the protruding portion to obtain a precisely defined opening, that is to say precise dimensions. The opening after machining can be conical or cylindrical. A precisely defined opening thus makes it possible to improve the accuracy of the installation of the degassing system and the seal between the cylinder head and the degassing system.

In operation, the water core of the cylinder head 10 and the degassing system 51, 52 are used in the following manner.

The water core is here designed so that the circulation of water in this water core is made in a direction substantially transverse to the direction of the axis of the cylinder head 10.

The pressurized water, from the cylinder block located under the cylinder head, enters the water core of the cylinder head through the inlet channels 91, 92, 93. In particular, the water from the inlet channel 91 is directed into the lower peripheral channel 97 and water from the inlet channel 93 is directed into the opposed lower peripheral channel 99 to cool the lower portion of the cylinder head surrounding the exhaust valves 12, 13, while the water from the inlet channel 92 is directed into the lower central channel 98 to cool the portion of the cylinder head near the fuel injector 15. The lower peripheral channels 97 and 99 are of smaller section than the central channel lower 98, so the water circulates mainly through this lower central channel 98 oriented substantially transversely to the axis of the cylinder head 10. The water is then guided in the central connecting channel 89 and fills the upper central channel 72 which allows and cooling the upper central part of the cylinder head surrounding the fuel injector and passing between the exhaust valves 12, 13. Then, the water passes through the channel 74 which extends the upper central channel 72 passing between the valves. 1 1, 14 and is also distributed in the peripheral channels 71, 73 of the upper part of the water core to descend into the cylinder block via the connection channels 87, 88 and the output channels 94, 95 connected to the peripheral lower channel 96. Thus, the water enters the side of the cylinder head 10 which receives the exhaust valves 12, 13 and leaves the opposite side with respect to the axis of the cylinder head, near the intake valves 1 1, 14.

During the circulation of the water in this water core, the air bubbles reach the upper part of the water core and slide, according to the arrow shown in Figure 1, on the inclined wall of the upper part of the water core. water core to accumulate in the chamber generated by the protruding portion 6. The bleed screw 52 can then be unscrewed periodically to evacuate the air bubbles. Of course, the water core, and its operation, detailed above for a cylinder is generalizable to several cylinders.

The present invention is not limited to the embodiment described and shown, but the art can apply any variant within his mind.

Claims

1. A method of manufacturing a cylinder head (10) of an internal combustion engine characterized in that it comprises the following steps:

- Making a mold positive (7) for the formation of a water core of the cylinder head (10), the positive (7) of the water core comprising a main part

(8,9) and a protruding portion (6),

- positioning the positive (7) of the water core of the cylinder head (10) on a core of walls (20) of the cylinder head (10), the protruding portion (6) being supported on a portion of the core of walls (20) of the cylinder head (10), - after closing the wall core (20) of the cylinder head (10), injecting metal into the wall core (20) of the cylinder head (10),

- Destruction of the positive (7) of the water core and evacuation of the material constituting the positive (7) of the water core, the protruding portion (6) of the positive (7) of the water core generating a corresponding protruding portion water core,

- Establishment of a degassing system (51, 52) associated with the corresponding protruding portion of the water core.

2. Method according to the preceding claim, characterized in that said positive is carried out so that said protruding portion (6) is the highest part of the positive (7) of the water core, in a configuration of this positive. corresponding to a normal configuration of use of the engine.

3. Method according to one of the preceding claims, characterized in that the evacuation of material constituting the positive (7) of the water core is formed by the corresponding protruding portion (6) of the water core.

4. An internal combustion engine cylinder head core positive for molding such a cylinder head, having a main part (8,9) and a protruding bearing part (6), characterized in that the part protruding (6) of the positive (7) is the highest part of the positive, in a positive configuration corresponding to a normal configuration of use of the engine.

5. Molded cylinder head of an internal combustion engine, within which is formed a water core comprising a main part (8, 9) and a protruding part (6), characterized in that said protruding part (6) opens out of the cylinder head (10) by an opening which is derived from the casting of the cylinder head (10) and which is closed by a closure plug (51) associated with a degassing system (52).

6. Cylinder head according to the preceding claim, characterized in that the protruding portion (6) of the water core is the highest part of the water core, in a normal configuration of use of the engine.

7. Cylinder head according to the preceding claim, characterized in that the main part (8,9) of the water core having a lower portion (9) and an upper portion (8), the lower portion (9) is connected to a first portion (P1) of the upper portion (8) and the protruding portion (6) is connected to a second portion (P2) of the upper portion (8) of the water core.

8. Cylinder head according to the preceding claim, characterized in that the first portion (P1) and the second portion (P2) of the upper part (8) of the water core are substantially distributed on either side of the center of the upper part (8) of the water core.

9. Cylinder head according to one of claims 5 to 8, characterized in that the degassing system (51, 52) comprises a degassing screw (52) located in the closure cap (51).

10. Cylinder head according to the preceding claim taken in dependence on claim 6, characterized in that the degassing screw (52) is located in the upper part of the closure plug (51).

1 1. Cylinder head according to one of claims 5 to 10, characterized in that the lower part of the cylinder head (10) constituting the upper part of several aligned cylinders of the engine to which the cylinder head belongs, the water core of the cylinder head is arranged such that the circulation of water in the water core is made in a direction generally transverse to the direction of the axis passing through the centers of the cylinders.