EP2404051B1 - Dual material device, casing and vehicle provided with said device, and method for making said device - Google Patents

Description

The invention relates to a two-component device comprising an insert and a part. The invention also relates to a housing and a vehicle equipped with this device and a method of manufacturing this device.

Known two-component devices comprise an insert, a part made of a material different from the insert, this insert and this part being assembled by molding one around the other, the interface between the insert and the part defining at least one joint plane, and a bore for receiving a pin, formed in this device and passing through the joint plane, this bore having an inlet chamfer for guiding the pin to a fitting section of this pin.

Typically, these known devices are found in motor vehicle combustion engine housings. Indeed, a crankcase of a motor is divided into two parts respectively called "crankcase" and "crankcase cap" or "crankcase". For example, the cap housing includes cast iron inserts forming bearings for the crankshaft. Each insert is embedded in an aluminum part that forms the frame of the hat housing. This assembly of the insert and the aluminum part is obtained by molding the aluminum around the insert.

However, the cast iron has metallurgical characteristics that are different from those of the aluminum part. For example, cast iron and aluminum do not have the same melting point,

Thus, although the insert is firmly adhered to the aluminum part, cast iron and aluminum do not mix during the manufacture of the cap. There is therefore an interface between the insert and the aluminum part which defines one or more joint planes between the materials of these elements.

In addition, several bores for receiving centering pins are formed in the cap housing. These pins make it possible to precisely dispose the cylinder block on the hatch cover. These bores cross the join plane.

Such a device is for example known from DE 102005031038 or DE 100 40 476 C1

It is in this context that it was found that when mounting the motor, the machine for mounting the centering pins in the bores frequently encountered problems. For example, it happens that the pressure of fitting of the pin in the bore is too high, which defaults this machine. In addition, the pinning of the hat and cylinder housings is sometimes bad, which can damage the engine.

The invention aims to remedy these problems by providing an improved device to facilitate the fitting of the pin in the bore.

It therefore relates to a two-component device in which the input chamfer extends beyond the joint plane.

It has been found that at the joint plane, since the insert does not mix with the workpiece during molding, a shoulder of material is formed which projects into the bore. This shoulder flu the introduction of the pin inside the bore. This explains the fault of the mounting machine and the damage to some casings.

The entry chamfer allows a slight lateral movement of the pin during its introduction into the bore. This lateral movement allows to guide and correctly position the pin before tightening in the fitting section. For this purpose, the input chamfer has a diameter strictly greater than the fitting section in which the pin is clamped and therefore to the diameter of the pin.

In the above device, the input chamfer extends beyond the join plane. Thus, in the joint plane, the diameter of the bore is strictly greater than the diameter of the pin to be introduced. Under these conditions, even if there is a slight shoulder protruding inside the bore at the joint plane, it does not prevent the passage of the pin because the deflection lateral is sufficient. Therefore, in the above device, galling of the pin when introduced into the bore is avoided. Defects of the mounting machine and damage to the engine equipped with this device are also reduced or eliminated.

• ▪ la plus grande largeur transversale de la section d'emmanchement dans un plan parallèle au plan de jointure est strictement inférieure à la plus grande largeur transversale du chanfrein d'entrée dans le plan de jointure ;
• ▪ la différence entre les plus grandes largeurs transversales de la section d'emmanchement et du chanfrein d'entrée est au moins supérieure à 0,05 mm et de préférence supérieure à 0,5 mm ;
• ▪ l'insert et la pièce sont réalisés dans des métaux différents ;
• ▪ l'insert est réalisé en fonte et la pièce en aluminium ;
• ▪ le dispositif comprend aussi la goupille serrée dans l'alésage, cette goupille étant réalisée dans un matériau dont la dureté est inférieure ou égale à la dureté d'au moins l'un des matériaux utilisés pour réaliser l'insert et la pièce ;
• ▪ l'insert forme un palier pour un vilebrequin d'un moteur à combustion et la pièce forme une partie d'un carter de ce moteur à combustion.

The embodiments of this device may include one or more of the following features:

• The greatest transverse width of the fitting section in a plane parallel to the joint plane is strictly less than the largest transverse width of the chamfer entering the joining plane;
• The difference between the largest transverse widths of the fitting section and the input chamfer is at least greater than 0.05 mm and preferably greater than 0.5 mm;
• ▪ the insert and the part are made of different metals;
• ▪ the insert is made of cast iron and the aluminum part;
• ▪ the device also comprises the pin clamped in the bore, this pin being made of a material whose hardness is less than or equal to the hardness of at least one of the materials used to make the insert and the workpiece;
• ▪ The insert forms a bearing for a crankshaft of a combustion engine and the part forms part of a crankcase of the combustion engine.

The invention also relates to a casing of a combustion engine of a vehicle equipped with the device above.

The invention also relates to a vehicle comprising this housing.

Finally, the subject of the invention is also a method of manufacturing this two-material device comprising the machining of an input chamfer so that this input chamfer extends beyond the joining plane.

• La figure 1 est une illustration schématique et en coupe d'un véhicule équipé d'un carter de moteur à combustion,
• la figure 2 est une illustration schématique et en coupe d'un alésage réalisé dans le carter de la figure 1 pour recevoir une goupille de centrage,
• la figure 3 est un agrandissement d'un détail de la figure 2,
• la figure 4 est une illustration schématique et en perspective d'un carter chapeau du carter de la figure 1, et
• la figure 5 est un organigramme d'un procédé de fabrication et de montage du carter de la figure 1.

The invention will be better understood on reading the description which follows, given solely by way of nonlimiting example and with reference to the drawings in which:

• The figure 1 is a schematic and sectional illustration of a vehicle equipped with a combustion engine casing,
• FIG. 2 is a diagrammatic sectional illustration of a bore made in the casing of the figure 1 to receive a centering pin,
• FIG. 3 is an enlargement of a detail of FIG.
• the figure 4 is a schematic and perspective illustration of a crankcase hat figure 1 , and
• the figure 5 is a flowchart of a process for the manufacture and assembly of the housing of the figure 1 .

The figure 1 represents a vehicle 2 equipped with a casing 4 of a combustion engine. The vehicle 2 is shown schematically by a dotted rectangle. This vehicle 2 is for example a motor vehicle such as a car.

The casing 4 comprises an upper part 6 called "cylinder block" and a lower part 8 called "casing cap". These upper and lower parts are joined to one another at a substantially horizontal assembly plane 10 in the figure 1 .

The cylinder block is conventional and will not be described here in more detail.

The cap housing 8 comprises an insert 12 embedded without any degree of freedom in a shell 14. The insert 12 forms a bearing of a crankshaft of the combustion engine to be received in the housing 4. For example, the upper part of the insert 12 defines a face 16 in the form of a semicircle. This face 16 is intended to receive the crankshaft rotationally. To limit the wear of this face 16, the insert 12 is made of a very hard material such as cast iron.

Here, the insert 12 is traversed vertically by two fixing holes 18 and 20. These holes 18 and 20, when the cap and cylinder housings are assembled, extend beyond the assembly plane 10 inside the cylinder block 6. The ends of these holes 18 and 20 located inside the housing cylinder 6 are threaded. Indeed, these holes 18 and 20 are intended to receive screws fixing the cap housing on the cylinder block.

The shell 14 is made of a less hard material than that used to make the insert 12. For example, the shell 14 is made of aluminum. To fix the insert 12 in the shell 14, it is inserted during the molding of the shell 14. Since the material of the shell 14 has metallurgical characteristics different from those of the material used to make the insert 12, the materials of the shell 14 and the insert 12 do not mix. For example, the materials of the insert 12 and the shell 14 have different melting points.

Once cooled, there is an interface 24 between these two materials.

On the figure 1 two bores 26, 28 are also visible. These bores 26 and 28 are hollowed vertically first in the shell 14 and then in the insert 12 to end in the cylinder block 6. These bores 26, 28 extend along respective vertical axes 30, 32.

For example, the bores 26 and 28 are identical and only the bore 26 will be described here in detail.

The bore 26 extends from bottom to top. It therefore has an opening 34 through which must be introduced the centering pin located at the bottom. Then, going up from this opening 34, the bore 26 has a chamfer 36 input which is extended by a fitting section 38. The chamfer 36 is designed to guide the pin introduced and to align the axis of this pin on the axis 30 before its introduction into the section 38. For this purpose, the inner diameter of the chamfer 36 decreases progressively from the diameter of the opening 34 up to the diameter of section 38. For example, the diameter of the chamfer 36 decreases in steps.

The section 38 is intended to retain by clamping the pin introduced into the bore 26. For this purpose, the diameter of the section 38 is chosen to allow a force fit of the pin. For example, the diameter of the section 38 is equal to the diameter of the pin to be introduced.

Here, the bore 26 passes through the interface 24 between the shell 14 and the insert 12 at a joint plane 40.

Here, this plane 40 is perpendicular to the axis 30.

An area E surrounding this plane 40 is shown in more detail in FIG.

The chamfer 36 extends, upward, beyond the plane 40. Thus, in the plane 40, the chamfer 36 has an inner diameter Φ ₁ strictly greater than the inner diameter Φ ₂ of the section 38. For example, the diameter Φ ₂ is equal to the diameter of the pin intended to be introduced into the bore 26.

A zone F surrounding the intersection of the chamfer 36 with the insert 12 at the plane 40 is shown in enlarged form in FIG.

Because of the difference of the materials forming the shell 14 and the insert 12, at least one of these materials forms a shoulder 44 (Figure 3) projecting inside the bore 26. For example, here, it is the insert 12 which forms the shoulder 44.

This shoulder 44 protrudes a few hundredths or a few tenths of a millimeter inside the bore 26. However, here, the difference between the diameters Φ ₁ and Φ ₂ is chosen sufficiently large that the shoulder 44 can not not cause seizing of the pin during its insertion into the bore 26. The difference between the diameters Φ ₁ and Φ ₂ is chosen greater than 0.05 mm and preferably greater than 0.5 mm. Thus, even if a shoulder 44 is formed, it is set back relative to the section 38 and therefore does not interfere with the introduction of the pin in this section.

Here, the hardness of the material of the insert 12 is greater than or equal to the hardness of the material used to make the pin to be introduced.

The figure 4 represents the hat cover 8 in perspective. This perspective view shows that the cap housing 8 has several inserts identical to the insert 12.

The manufacture and assembly of the casing 4 will now be described in more detail with regard to the method of the figure 5 .

Initially, it starts with a stage 50 of manufacture of the cap housing 8. This phase 50 comprises a step 52 during which the aluminum is cast around the insert 12 in a mold to form the shell 14 on which is rigidly fixed insert 12. During this molding step, it is assumed that an air film is present between the insert 12 and the shell 14, which prevents a perfect seal of the insert 12 on the shell 14.

Then, during a step 54, the cylinder block 6 is assembled above the cap housing 8 and joined to one another via the assembly plane 10.

In this position, during a step 56, the holes 18, 20 and the bores 24 and 26 are machined.

In particular, during step 56, the input chamfer 36 and the section 38 are made such that the input chamfer extends beyond the plane 40.

Then, once the different machining operations have been performed, a phase 60 of the motor assembly is carried out.

In a step 62, after installing the crankshaft, the cylinder block 6 is centered on the cap housing 8 using, for example, centering pins. Then, during a step 64, centering pins are introduced into the bores 26 and 28 until their ends are fitted inside the sections 38. Therefore, these centering pins are held tight to the inside. inside the bores 26 and 28.

Finally, during a step 66, screws are inserted into the holes 18 and 20 to finalize the assembly of the cylinder and cap housings.

Many other embodiments are possible. For example, the cross section of the bores and centering pins is not necessarily circular. For example, they may be cylindrical but with a director different from a circle.

What has been described here in the particular case of a bimaterial hatch also applies to any two-material device. It is also not necessary that the materials of this device are cast iron and aluminum. It may for example be two other metals with different metallurgical characteristics. What has just been described also applies to two-material devices in which at least one or both of these materials is not a metal.

Claims (10)

1. A dual material device including an insert (12), a part (14) made of a material different than that of the insert, this insert and this part being assembled by moulding one around the other, the interface between the insert and the part defining at least one joint plane (40), and a bore (26, 28) for receiving a pin, formed in this device and passing through the joint plane, this bore having an inlet chamfer (36) for guiding the pin up to a fitting section (38) of this pin, characterized in that the inlet chamfer (36) extends beyond the joint plane (40).
2. The device according to claim 1, in which the greatest transverse width of the fitting section (38) in a plane parallel to the joint plane is strictly less than the greatest transverse width of the inlet chamfer (36) in the joint plane.
3. The device according to claim 2, in which the difference between the greatest transverse widths of the fitting section and of the inlet chamfer is at least greater than 0.05 mm and preferably greater than 0.5 mm.
4. The device according to any one of the preceding claims, in which the insert (12) and the part (14) are made of different metals.
5. The device according to claim 4, in which the insert (12) is made of cast iron and the part (14) is made of aluminium.
6. The device according to any one of the preceding claims, in which the device also includes the pin fitted tightly in the bore, this pin being made of a material having a hardness which is less than or equal to the hardness of at least one of the materials used to make the insert (12) and the part (14).
7. The device according to any one of the preceding claims, in which the insert (12) forms a bearing for a crankshaft of an internal combustion engine and the part (14) forms a portion of a casing of this internal combustion engine.
8. A casing (4) of an internal combustion engine of a vehicle, characterized in that it comprises a device according to any one of the preceding claims.
9. A vehicle (2), characterized in that it includes a casing according to claim 8.
10. A method for manufacture of a device according to any one of claims 1 to 7, characterized in that this method includes the machining (56) of the inlet chamfer such that this inlet chamfer extends beyond the joint plane.

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