WO2005105338A2

WO2005105338A2 - Cylinder block, moulding method and engine comprising one such cylinder block

Info

Publication number: WO2005105338A2
Application number: PCT/FR2005/001088
Authority: WO
Inventors: Cyril Peronnet; Alain Guffroy
Original assignee: Peugeot Citroën Automobiles Sa.
Priority date: 2004-04-30
Filing date: 2005-04-29
Publication date: 2005-11-10
Also published as: FR2869556A1; WO2005105338A3; EP1781434A2; ATE528088T1; FR2869556B1; EP1781434B1; ES2371082T3

Abstract

The invention relates to a cylinder block (1) for an internal combustion engine, consisting of: an upper part (2) comprising a plurality of cylindrical bores (3) which are aligned along a longitudinal axis and a water sleeve (3) which surrounds the bores; and a lower part (4) such as a skirt, which defines a space for a crankshaft mechanism. The inventive cylinder block (1) comprises two longitudinal faces which are disposed on either side of the line of cylindrical bores (3) and at least one of said faces is equipped with at least one shell assembly, said shell assembly forming chambers which are not connected to one another and comprising an outer common wall which extends continuously along part of the length of one longitudinal face. The invention also relates to an internal combustion engine comprising one such cylinder block, as well as a moulding method for producing such cylinder blocks.

Description

Cylinder block, molding process and engine comprising such a cylinder block

The invention relates to a cylinder block of an internal combustion engine as well as to an engine comprising such a cylinder block. The invention also relates to a molding process for the production of cylinder blocks according to the invention.

The invention relates more particularly to a cylinder block comprising, an upper part comprising a plurality of cylindrical bores aligned in a longitudinal direction, a water envelope surrounding them, and a lower part, such as a skirt, delimiting a volume for a crankshaft mechanism.

The combustion noises radiated by an internal combustion engine are a function of this combustion (which is the excitation phenomenon) and of the dynamic response (vibrations) of the Powerplant to this excitation.

The engines are subjected to increasingly severe pollution standards which are very restrictive for the development of combustion. As a result, the potential for reducing combustion noise by developing the combustion itself is increasingly reduced. For this reason, it is known to propose modifications to the architecture of the engine to better control its acoustic radiation. The known solutions are however not very satisfactory in terms of reduction of the noise generated by the engine and / or involve complex architectural modifications often incompatible with large-scale production. An object of the present invention is to overcome all or part of the drawbacks of the prior art noted above.

To this end, the cylinder block according to the invention, furthermore in accordance with the generic definition given in the preamble above, is essentially characterized in that at least one of the two longitudinal faces of the cylinder block comprises at minus a first set of boxes forming non-chambers communicating with each other and having a common external wall extending without discontinuity over part of the length of a longitudinal face.

Each set or row of boxes constitutes a longitudinal reinforcement line. Furthermore, the vertical spaces delimiting the partitions of the boxes form a series of vertical reinforcements.

Preferably, the boxes have a thickness of between 15 and 30 mm approximately. The area covered by each set of boxes extends over a length of at least two thirds, and preferably at least three quarters, of the length of the longitudinal face of the casing, and each set of boxes has a height of between 3 and approximately 20% of the height of the longitudinal faces.

In a particularly preferred arrangement, the casing comprises at least two rows of boxes (i.e. 4 sets), a first row being for example located substantially at the transition between the bores intended to receive the pistons and the lower part of the cylinder block (or skirt) delimiting the volume for the crankshaft mechanism and a second row preferably located approximately halfway up the lower part of the cylinder block.

A particularly simple means of carrying out the invention consists in modifying the central core used for molding the casing to form a series of protrusions which will delimit the volumes of the boxes. Under these conditions, boxes are advantageously obtained whose interior spaces communicate locally with the interior volume of the cylinder block, but without the boxes communicating with each other.

The invention also relates to an internal combustion engine comprising a cylinder block conforming to any one of the preceding characteristics.

Other particularities and advantages will appear on reading the description below, made with reference to the figures in which:

- Figure 1 is a perspective view of a cylinder block according to the invention, cut transversely along a plane passing through the cylinder bore; - Figure 2 shows a side view of the cylinder block of Figure 1, on the exhaust side; - Figure 3 shows a side view of the cylinder block of Figure 1, on the intake side;

FIGS. 4 and 5 respectively represent perspective views of the longitudinal faces of the cylinder block of FIGS. 1 to 3,

FIG. 6 is a schematic view of an exemplary arrangement of a one-piece foundry core adapted to allow the molding of the cylinder block of FIGS. 1 to 5,

FIG. 1 illustrates a cylinder block 1 of an internal combustion engine according to a preferred embodiment of the invention.

Conventionally, the cylinder block 1 - of a generally essentially rectangular shape - comprises an upper part 2 comprising a plurality of vertical cylindrical bores 3 which are aligned in a longitudinal direction. The bores 3 delimit the cylinders of the engine intended to receive pistons. A water jacket 4 is provided in the upper part so as to surround the bores 3.

The cylinder block 1 also comprises a lower part 5, such as a skirt, and delimiting a volume for a crankshaft mechanism (not shown).

Preferably, the upper 2 and lower 5 parts are made of a metallic material and are molded in one piece. By considering this cylinder block as a parallelepiped, it is delimited vertically by an upper face intended to receive a cylinder head (not shown) and by a lower face intended to receive an oil pan for example. Likewise, it is delimited laterally by two longitudinal faces situated on either side of the alignment of the cylindrical bores 3 and two transverse faces. The longitudinal faces are sometimes called respectively "intake face" and "exhaust face", with reference to the path of the fresh and burnt gases with respect to the cylinders.

In the embodiment of the invention shown in Figure 1, each of the longitudinal faces of the cylinder block 1 has two lines 6, 7 of longitudinal reinforcement. Each reinforcement line is in fact constituted by the juxtaposition of a series of boxes having a common external wall, but with a series of vertical walls which form partitions.

In a very particularly preferred variant of the invention, the thickness of this external wall is between 4 and 5 mm approximately. The interior chamber defined by a box is typically between 15 and 30 mm.

The distance between two adjacent rows (for example between the row situated on the upper part and the row situated in the lower part) can be between 4 and 80 mm for example. In addition, each row has a width of, for example, between 3 and 20% approximately of the height of the longitudinal faces (width of, for example, between 30 and 80 mm).

Each row of boxes is preferably parallel to the direction of alignment of the cylindrical bores 3. More specifically, the reinforcing assemblies 6, 7 are preferably parallel to the upper and lower faces of the cylinder block 1.

Even if each row is partitioned, the external wall is continuous so that each assembly extends without discontinuity over substantially the entire length of the longitudinal faces of the cylinder block 1. However, the reinforcement assemblies can extend continuously over two thirds, and preferably at least three quarters, of the length of the longitudinal face. In this case, the longitudinal reinforcement rows are preferably centered on the middle part of the longitudinal face.

In the case shown here, the cylinder block is provided with two times two rows of reinforcement, with a first row 6 located substantially halfway up the lower part 4 of the cylinder block. This gives better transverse rigidity to the skirts, thus improving their bending behavior.

Furthermore, a second reinforcing row 7 is preferably arranged substantially at the transition between the upper 2 and lower 4 parts of the cylinder block 1. That is to say that the first reinforcing line 15 is located at the connection between the barrels (cylinders 3) and the engine skirt. This longitudinal reinforcement line 7 allows better joining between the upper 2 and lower 3 parts of the cylinder block 1 and improves the behavior thereof when subjected to torsional forces.

The invention thus allows a structural reinforcement of the cylinder block 1 and a reduction of the noises radiated by the engine when it is subjected to torsional and / or bending forces. In particular, when the cylinder block 1 is subjected to vibrational excitations of between 800 and 3000 Hz, the noise generated by the vibration of the block 1 is reduced from 2 to 3dB compared to known cylinder blocks. The attenuation of noise is particularly important around the frequencies between 2500 and 2700 Hz as well as between 1000 and 1800 Hz. In the example of embodiment proposed in FIG. 2, a third row of reinforcement 8 is provided.

The partitions delimiting two consecutive boxes of the same row also constitute vertical reinforcement lines arranged regularly along the longitudinal faces of the cylinder block. These reinforcement lines are oriented from bottom to top on the cylinder block.

These vertical partitions participate in stiffening the cylinder block which is thus menu of a mesh practically forming a dimension of reinforcement lines.

FIG. 3 illustrates a molding process which can advantageously be implemented for the production of cylinder blocks according to the invention. According to the embodiment illustrated very schematically in this Figure 3, four arrangements of cylinder blocks are arranged in an aligned manner in a mold. More precisely, the arrangements of nuclei are associated in pairs. The arrangements of each pair are joined face down against face down - that is to say that there are two clusters of two cylinder blocks joined to their base.

For the reinforcement according to the invention, each core is provided with a series of protrusions.

Between two protrusions are thus formed partitions, without longitudinal communication between the boxes delimited by these partitions. On the other hand, as these growths are attached by isthmus to the central core so that the interior chamber of each box communicates with the interior space of each cylinder.

As regards the embodiment also providing for a row of boxes approximately halfway up the barrel (case of FIG. 2), it is also necessary to provide protuberances on the core used for the water envelopes, as represented by example in FIG. 4 where the protuberances 8 ′ correspond to the boxes 8 of FIG. 2, and in which we recognize in particular the core elements 3 ′ corresponding to the cylinders 3.

Claims

1. Cylinder block (1) of an internal combustion engine comprising an upper part (2) comprising a plurality of cylindrical bores (3) aligned in a longitudinal direction and a water envelope (4) surrounding them, a part lower (5) such as a skirt and delimiting a volume for a crankshaft mechanism, the cylinder block (1) comprising two longitudinal faces located on either side of the alignment of the cylindrical bores (3), characterized in that at least one of the two longitudinal faces of the cylinder block comprises at least a first set of boxes forming non-communicating chambers with each other and having a common external wall extending without discontinuity over part of the length of a longitudinal face.

2. cylinder block (1) according to claim 1, characterized in that the boxes have a thickness of between approximately 15 and approximately 30 mm.

3. cylinder block (1) according to any one of the preceding claims, characterized in that a set of boxes extends over at least two thirds, and preferably at least three quarters, of the length of the longitudinal face .

4. cylinder block (1) according to any one of the preceding claims, characterized in that the height of a set of boxes is between 3 and 20% of the height of a longitudinal face.

5. cylinder block (1) according to any one of the preceding claims, characterized in that one of the sets of boxes is located substantially at the transition between the upper (2) and lower (4) parts of the cylinder block (1).

6. cylinder block (1) according to any one of the preceding claims, characterized in that one of the sets of boxes is located substantially halfway up the lower part (4) of the cylinder block (1).

7. cylinder block (1) according to any one of the preceding claims, characterized in that one of the sets of boxes is located substantially halfway up the upper part (2) of the cylinder block (1).

8. cylinder block (1) according to any one of the preceding claims, characterized in that the interior chamber of at least one box communicates at least locally with the interior volume of the cylinder block.

9. Internal combustion engine characterized in that it comprises a cylinder block according to any one of the preceding claims.

10. A method of molding at least one cylinder block of an internal combustion engine, comprising arranging an arrangement of a plurality of cores in a mold and pouring a metal into the mold, said cores of the arrangement comprising a central core (7) defining a lower part of cylinder block such as a skirt defining a volume for a crankshaft mechanism, an upper part of cylinder block defining a plurality of cylinders (3) aligned in a longitudinal direction, l arrangement comprising two longitudinal outer faces delimiting respectively two longitudinal walls of the cylinder block and situated respectively on either side of the alignment of the cylinders (3), characterized in that the central core is provided with a series of outgrowths delimited a reinforcement line consisting of a series of communicating boxes inside the cylinder block and not communicating with each other.

11.