Pipe system for a fluid, a method and an apparatus for connecting at least one duct part of a pipe system

A pipe system for a fluid, in particular a gas of an intake system (10) or a turbocharger of an internal combustion engine is disclosed. Also disclosed is a method and an apparatus for connecting at least one duct part (12) of a pipe system (10). The pipe system (10) has at least one blow-molded duct part (12) made of plastic and at least one fitting (18) for connecting the at least one blow-molded duct part (12) with another part (20) of the pipe system (10). The fitting (18) is inserted tight in the at least one blow-molded duct part (12). The at least one blow-molded duct part (12) is shrinked onto the at least one fitting (18).

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 USC 119 of EPO patent application EP 12290322.2 filed Sep. 28, 2012, and which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a pipe system for a fluid, in particular a gas, in particular of an intake system or a turbocharger of an internal combustion engine, in particular of a motor vehicle, having at least one blow-molded duct part made of plastic and at least one fitting for connecting the at least one blow-molded duct part with another part of the pipe system, whereby the fitting is inserted tight in the at least one blow-molded duct part.

The present invention relates further to a method for connecting at least one duct part of a pipe system for a fluid, in particular a gas, in particular of an intake system or a turbocharger of an internal combustion engine, in particular of a motor vehicle, with another part of the pipe system by use of at least one fitting, whereby the at least one duct part is made of plastic by a blow molding process and the at least one fitting is inserted tight in the at least one blow-molded duct part.

Additionally, the present invention relates to an apparatus for connecting at least one duct part of a pipe system for a fluid, in particular a gas, in particular of an intake system or a turbocharger of an internal combustion engine, in particular of a motor vehicle, with another part of the pipe system by use of at least one fitting, having an extruder for extruding a plastic material in a blowing mold for blow molding the at least one duct part and having a device for inserting the at least one fitting tight in the at least one blow-molded duct part.

BACKGROUND OF THE INVENTION

An air intake system of an internal combustion engine known from the market has a first blow-molded duct part made of plastic. A second duct part has a nipple for connection with the first duct part. The nipple of the second duct part is inserted in a connection end of the first duct part. The connection between the first duct part and the second duct part is fixed tightly by welding.

It is an object of the invention to provide a pipe system, a method and an apparatus for connecting at least one duct part of the pipe system of the above-mentioned kind, in which the connection may be realized easily directly inside the mold without external ejection process and the connection is reliable and tight.

SUMMARY OF THE INVENTION

The object is achieved by that, the at least one blow-molded duct part is shrinked mounted onto the at least one fitting.

According to the present invention, the at least one fitting is inserted in the at least one blow-molded duct part while the duct part is plasticized. Due to the shrinking a non-positive connection between the at least one blow-molded duct part and the at least one fitting may be realized which may be actuated by adherence. The at least one fitting is a male part. It may be a nipple or a pipe socket. The at least one fitting may be connected to a second duct part. A connecting end of the second duct part may be formed as a fitting. An external diameter of the at least one fitting, in particular the connecting end of the second duct part, can correspond to an internal diameter of the connection end of the at least one blow-molded duct part.

Preferably the external diameter of the at least one fitting may be between 15 mm and 70 mm. The internal diameter of the connection end of the at least one blow-molded duct part may be between 15 mm and 70 mm. The shape of the duct part may be circular or oval.

Preferably a wall thickness of the at least one fitting may be between 2 mm and 4 mm. A wall thickness of the at least one blow-molded duct part may be between 2 mm and 4 mm. The at least one fitting may be inserted in the at least one blow-molded duct part before the plasticized material of the blow-molded duct part is cooled down. During the cooling the at least one blow-molded duct part shrinks onto the at least one fitting, so a tight connection can be realized. Additional tools in particular for welding are not necessary. Advantageously the at least one fitting may be inserted during the blowing phase of the at least one blow-molded duct part. Preferably a radial outer surface of the at least one fitting may be graded in axial direction. So during the shrinkage the shape of the pipe wall of the at least one blow-molded duct part adapts to the outline of the radial outer circumferential side of the at least one fitting. In this way a positive locking connection between the at least one blow-molded duct part and the at least one fitting may be realized. The positive locking connection may be realized alternatively or additionally to the non-positive connection. In particular the radial outer surface of the at least one fitting may be sawtoothed, so the stability of the positive locking connection is further increased. In particular, the pipe system may be part of a turbo link, an air connection or a connection of a filter. Further, the pipe system may be part of a so-called Christmas tree configuration. A Christmas tree can be an assembly of valves, spools and fittings.

According to a favorable embodiment of the invention, the at least one blow-molded duct part may be connected to the at least one fitting by material engagement. The material engagement may be realized by fusing the materials of the at least one blow-molded duct part and the at least one fitting together. The fusion of the materials may be caused by the contact of the plasticized material of the at least one blow-molded duct part with the material of the at least one fitting. The fusion may be improved by the surface compression load due to the shrinking of the at least one blow-molded duct part. The tightness of the connection may be further increased by the material engagement. The material engagement may be realized additionally or alternatively to the non-positive connection or the positive locking connection.

Advantageously, the at least one fitting may be made of plastic. Preferably it may be made of polyamide. Polyamide is a thermoplastic which easy may be plasticized by heating. It hardens when it cools down. In particular the at least one fitting may be made of polyamide, which is chemically strengthened with 15% glass fiber. Preferably the at least one fitting may be made of a strengthened polyamide from Caprolactam, in particular known as “PA 6 15% GF”, or a polyamide known as “PA 666 15% GF”. Preferably, an external surface of the at least one plastic fitting may be plasticized before inserting in the at least one blow-molded duct part. For plasticizing the fitting may be heated. After inserting the fitting, the plasticized material of its surface can fuse with the plasticized material of the internal surface of the blow-molded duct part. So the material engagement between the at least one fitting and the at least one blow-molded duct part may be realized by chemical adhesion.

Advantageously, the at least one blow-molded duct part may be made of polyamide. Preferably the at least one blow-molded duct part may be made of polyamide, which is chemically strengthened with 15% glass fiber, known as “PA 6 15% GF” or “PA 666 15% GF”. Polyamide easy may be plasticized by heating. Plasticized polyamide may be hardened by cooling down. Plasticized polyamide can realize a material engagement with the radial outer surface of the at least one fitting.

According to a further favorable embodiment of the invention, the at least one blow-molded duct part and the at least one fitting may be made of different materials. The materials can differ in thermal conductivity and/or temperature resistance and/or electrical conductivity and/or mechanical stability and/or flexibility. In this way the at least one blow-molded duct part and the at least one fitting may be optimized for their function each. In particular the at least one fitting may be made of a rigid material. The at least one fitting may be made of a rigid plastic or a metal. The at least one blow-molded duct part may be made of a flexible material.

According to a further favorable embodiment of the invention, a gasket may be placed between the at least one blow-molded duct part and the at least one fitting. In this way the fluid seal tightness of the connection can be increased further.

The object is further achieved by the method in that, the plastic material for realizing the at least one blow-molded duct part is plasticized by heating and formed in a blowing mold, the plasticized at least one blow-molded duct part is shrinked onto the at least one fitting, the plasticized at least one blow-molded duct part is cooled down.

All features and advantages of the above-mentioned inventive pipe system apply analogous to the inventive method and its favorable embodiments.

Advantageously, the plasticized plastic material may be extruded. Therefore a method of suction extruding by use of an extruder may be performed. The extruded plastic material may be blow-molded by use of the blowing mold. Extruding and blow molding can happen during just several seconds. Scraps of the blow-molded duct part may be cut off. Then the plasticized at least one blow-molded duct part may be moved to the at least one fitting. Advantageously, the blowing mold with the blow-molded duct part may be moved to the at least one fitting. The at least one fitting may be strongly inserted in the plasticized at least one blow-molded duct part. Therefore the at least one fitting may be mounted on a lifter which may be positioned by an actuator. During the insertion of the at least one fitting, the at least one blow-molded duct part can still be placed within the blowing mold. After the insertion of the at least one fitting, the at least one blow-molded duct part may be cooled down. During the down cooling, the at least one blow-molded duct part can shrink tight on the at least one fitting. In this way, the at least one duct part is blow-molded on the at least one fitting, effectively.

According to a favorable embodiment of the invention, the at least one fitting may be heated before the plasticized at least one duct part is shrinked onto the at least one fitting. In this way the at least one fitting and the at least one duct part may be connected by material engagement. Advantageously, the at least one fitting may be made of plastic. Thus the plastic material of the at least one duct part and the material of the at least one fitting can fuse. So a material engagement between the at least one fitting and the at least one blow-molded duct part may be realized by chemical adhesion.

The object is further achieved by the apparatus by a cutting device for trimming the at least one blow-molded duct part, a driver for moving the blowing mold to the device for inserting the at least one fitting, whereby the device for inserting the at least one fitting has means for pushing the at least one fitting into the at least one duct part. The device for inserting the at least one fitting can also have heating means for heating the at least one fitting before pushing it into the at least one duct part. The extruder may be a suction extruder. All features and advantages of the above-mentioned inventive pipe system and the above-mentioned inventive method apply analogous to the inventive apparatus and its favorable embodiments.

In the drawings, equal or similar elements are referred to by equal reference numerals. The drawings are merely schematic representations, not intended to portray specific parameters of the invention. Moreover, the drawings are intended to depict only typical embodiments of the invention and therefore should not be considered as limiting the scope of the invention Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.

DETAILED DESCRIPTION

InFIG. 1a detail of an air intake system10of an internal combustion engine of a motor vehicle is depicted. The air intake system10has a first duct part12. The first duct part12is shown in a longitudinal section. The first duct part12is blow-molded of poly-amide. The polyamide is chemically strengthened with 15% glass fiber. Preferably so-called “PA6 15% GF” or “PA666 15% GF” can be used. An internal diameter of the first duct part12at its shown connection end16varies between 15 mm and 70 mm, preferably between 47 mm and 52 mm. The internal diameter is indicated inFIG. 1with a double arrow14. A wall thickness of the first duct part12is between 2 mm and 4 mm, preferably 3 mm.

The air intake system10further has a fitting18for connecting the first duct part12with a second duct part20of the air intake system10. The fitting18is a tube section. InFIG. 1it is shown in a side view. The fitting18is inserted tightly in the connection end16of the first duct part12. The first duct part12is shrinked onto the fitting18. The first duct part12is connected to the fitting18by a combination of material engagement, non-positive connection and positive locking connection.

The fitting18is made of plastic. It is connected in one piece to the second duct part20. The first duct part12and the fitting18are made of different materials. The radial outer circumferential side of the fitting18is sawtoothed in axial direction. An imaginary axis of the fitting18is indicated with a broken line22. The shape of the pipe wall of the first duct part12is adapted to the radial outer circumferential side of the fitting18. In this way the positive locking connection between the first duct part12and the fitting18is realized. An external diameter of the fitting18corresponds to the internal diameter14of the connection end16of the first duct part12. It is between 35 mm and 70 mm. Preferably it is between 47 mm and 52 mm. A wall thickness of the fitting18is between 2 mm and 4 mm, preferably 3 mm. Due to the tight shrinking of the first duct part12, the nonpositive connection by actuation by adherence is realized.

InFIGS. 2 and 3an apparatus24for connecting the first duct part12with the second duct part20by use of the fitting18is shown in two different production steps.

The apparatus24has an extruder26for extruding polyamide to a parison which is formed in a blowing mold28to the first duct part12. Further the apparatus24has a suction housing30, into which a leading end of the parison is sucked for forming the parison to the first duct part12. The suction housing30is placed on the opposite side of the extruder26. It has an opening31. In a state of extruding and blow molding of the first duct part12, the opening31is connected with an outlet opening32of the blowing mold28. The state of the apparatus24of extruding and blow molding of the first duct part12is shown inFIG. 2. The extruder26and the suction housing30are fixed relative to another.

Between the blowing mold28and the suction housing30a blade36for trimming the first duct part12is mounted on the suction housing30. The blade36is movable parallel to a surface of the blowing mold28, which abuts on the suction housing30. InFIG. 2a moving direction of the blade36is indicated with an arrow38.

The blowing mold28is movable in direction of an arrow34relative to the extruder26and the suction housing30toward a device for inserting40the fitting18tight in connection end16of the first duct part12. Therefore the apparatus24has a driver42for moving the blowing mold28toward the device for inserting14. A housing44of the device for inserting40is affixed to the suction housing30by a bridge46. At a further favorable contrary embodiment, the blowing mold28is fixed and the fitting apparatus is moved.

The housing44has a cylindrical interior48, in which the second duct part20with the fitting18can be placed. At a front side of the interior48the housing44has an assembling opening50. In the state of inserting the fitting18, the assembling opening50is coaxial to the outlet opening32of the blowing mold28. The state of inserting the fitting18of the apparatus24is shown inFIG. 3.

On the side opposite to the assembling opening50, the housing44has an actuator opening52. The actuator opening52is coaxial to the assembling opening50. A piston54of an actuator56leads through the actuator opening52. The piston54is movable in the interior48. A moving direction of the piston54is axial to the interior48. InFIG. 3, the moving direction is indicated with an arrow58.

Near the assembling opening50, a cylindrical heating element60is placed at the radial inner circumferential side of the housing44. Preferably the heating element60is electrically operated.

An exemplary method for connecting the first duct part12with the second duct part20by use of the fitting18is described with the help ofFIGS. 2 and 3.

The apparatus24is in its state of extruding as shown inFIG. 2. The extruder26is provided with the polyamide for the first duct part12. The pre-casted second duct part20with the fitting18is placed in the interior48of the housing44of the device for inserting40. The fitting18is coaxial to the assembling opening50. The free end of the fitting18points to the assembling opening50. The second duct part20is mounted on the free end of the piston54. The fitting18is placed inside the heating element60.

The polyamide is heated and plasticized within the extruder26. The plasticized polyamide is extruded with the extruder26and blown to the parison in the blowing mold28. The parison is sucked with its leading end into the suction housing30. So the parison is sucked into the blowing mold28and formed to the first duct part12.

The blade36is moved in direction38to cut off the scrap62of the leading end of the first duct part12which is within the suction housing30. So the first duct part12is trimmed.

The blowing mold28together with the first duct part12is moved in direction34toward the device for inserting40. As it is shown inFIG. 3, the leading end, which realizes the connection end16of the first duct part12, then is coaxial to the fitting18in the interior48of the housing44.

The fitting18is heated by the heating element60. The radial outer surface of the fitting18so is plasticized.

The piston54is moved by the actuator56in moving direction58toward the assembling opening50, so that the fitting18is pushed in the still plasticized connection end16of the first duct part12.

The plasticized first duct part12is cooled down. For this the blowing mold28can be cooled down. Thereby the plasticized first duct part12is shrinked onto the fitting18. During the shrinkage of the first duct part12the shape of its pipe wall adapts to the profile of the radial outer circumferential side of the fitting18. The plasticized material on the radial outer circumferential side of the fitting18fuses with the plasticized material of the first duct part12for realizing the material engagement. The first duct part12and the second duct part20are connected tight by use of the fitting18.

After the connection of the first duct part12with the fitting18is firm, the blowing mold28is removed from the housing44. The blowing mold28is opened and the first duct part12with the fitting18and the second duct part20are removed.

The invention is not limited to an air intake system10of an internal combustion engine of a motor vehicle. The invention can also be applied for other kinds of pipe systems for fluids. For example it can be used for a turbocharger of an internal combustion engine. The invention can be applied for pipe systems for other gases or liquids, for example oil, fuel or water. The invention is further applicable to other kinds of internal combustion engines, for example to industrial engines.

The air intake system10can have more than one blow-molded first duct part12. The air intake system10can have more than one fitting18.

Instead of being connected with the second duct part20, the first duct part12can also be connected with another part of the air intake system10, for example with a housing of an air filter or a so-called Christmas tree.

The internal diameter14of the connection end16of the first duct part12can be less than 35 mm or more than 70 mm. Accordingly, the external diameter of the fitting18can be less than 35 mm or more than 70 mm.

The wall thickness of the first duct part12can be less than 2 mm or more than 4 mm. The wall thickness of the fitting18can be less than 2 mm or more than 4 mm.

Instead of being sawtoothed the radial outer circumferential side of the fitting18can be graded in axial direction in a different way. For example it can be wavy. The radial outer circumferential side of the fitting18can also be straight in axial direction.

The connection between the first duct part12and the fitting18can be realized by material engagement or non-positive connection, in particular actuation by adherence, or positive locking connection or a combination of those connection types.

The first duct part12also can be made of polyamide which is strengthened with more or less than 15% glass fiber. Also polyamide without glass fiber can be used. The first duct part12can also be made of another kind of plastic material.

The fitting18can also be made of polyamide. The polyamide also can be chemically strengthened with 15% glass fiber, for example so-called “PA6 15% GF” or “PA666 15% GF”. Also polyamide with more or less than 15% glass fiber or without glass fiber can be used. The fitting18also can be made of a material different from plastic. For example it can be made of metal.

The first duct part12and the fitting18can also be made of the same material.

A gasket can be placed between the first duct part12and the fitting18.

Instead of one cylindrical heating element60also multiple heating elements can be placed at the radial inner circumferential side of the housing44.

The order of the procedural steps of the exemplary method for connecting the first duct part12with the fitting18can be different.

Also an alternative method for connecting the duct parts12and20by use of the fitting18can be applied, which differs from the described exemplary method.

The first duct part12can be shrinked onto the fitting18without heating the fitting18beforehand.

The first duct part12can be connected with the fitting18by use of an apparatus different from the exemplary described apparatus24.