METHOD FOR INDIVIDUALLY MANUFACTURING A SUBASSEMBLY OF EXHAUST LINE COMPONENTS USING A TEMPLATE

Abstract

The invention relates to a method for individually manufacturing a sub-assembly (34) of components of a motor vehicle exhaust system at a manufacturing station, characterized in that only the sub-assembly (34) is delivered pre-assembled to the manufacturing station, at least one jig (36) being pre-mounted on the pre-assembled sub-assembly (34) to replace any missing supplementary reference elements of the sub-assembly (34) in order to allow the correct positioning of the sub-assembly (34) on the processing station without modifying the positioning means (33) of said station relative to a "complete" operating mode in which the station receives a complete assembly. The invention also relates to a jig for implementing the method.

Description

DOMAINE TECHNIQUE DE L'INVENTION

[0001] The present invention relates to a method for individually manufacturing a subset of elements of a motor vehicle exhaust line on a manufacturing station. ARRIERE PLAN TECHNIQUE DE L'INVENTION

[0002] The invention relates more particularly to a method for individually manufacturing a subset of elements of a motor vehicle exhaust line on a manufacturing station, the subset being intended to be connected to other elements to form an assembly of the exhaust line, at least one complementary element of the assembly not being part of said subset, in a first mode of use called "complete" of the manufacturing station, all the elements of the assembly are delivered pre-assembled on the manufacturing station, at least one complementary element, called reference element, forming a geometric reference enabling positioning means of the station to position the assembly relative to tools of the station.

[0003] Generally, a vehicle's exhaust system consists of several components connected to form a complete assembly. One such assembly is, for example, a section of the vehicle's exhaust system. This assembly includes a pipe that guides the exhaust gases from an inlet to an outlet.

[0004] The various components of this assembly are joined by welding on a manufacturing station, in this case a welding station. Such a manufacturing station is used in an assembly line production process. It is equipped with tools, in this case welding tools, carried by robotic arms that allow the components to be joined quickly and automatically.

[0005] Such an exhaust system assembly comprises several elements, the simplest of which are in the form of tubular pipes.

[0006] Modern exhaust systems also include several components with specific functions. For example, some components are equipped with exhaust gas treatment devices, such as particulate filters. As another example, in current vehicles, it is common practice to mix intake air with exhaust gases to reduce the production of pollutants during combustion. To achieve this, a component includes a recirculation valve designed to divert a portion of the exhaust gases into a recirculation circuit.

[0007] Such an exhaust system assembly most often features bends to adapt the geometry of the exhaust system assembly to the vehicle configuration.

[0008] In addition, some components of the exhaust line have an asymmetrical shape relative to the axis of gas flow in the duct.

[0009] Due to this particular geometry and the asymmetrical shape of each component, the entire exhaust system must be positioned very precisely in the manufacturing station to allow for precise welding of the various elements together.

[0010] To this end, the manufacturing station is equipped with positioning systems, such as those for orienting the assembly geometrically. These positioning systems use certain elements as geometric references. This allows the fastening tools to be automatically controlled to weld each assembly in series without operator intervention.

[0011] Furthermore, certain exhaust system sub-assemblies are designed to be individually replaced in the exhaust system of a used vehicle, for example, following normal wear and tear or a vehicle accident. For this reason, these sub-assemblies must be capable of being individually mass-produced for individual delivery as spare parts.

[0012] However, subassembly production cannot be carried out directly on the manufacturing station used to produce the complete exhaust system. This is because the subassembly typically lacks all the reference elements needed to correctly position it on the manufacturing station's positioning devices. Therefore, new positioning devices adapted to the specific subassembly must be designed.

[0013] However, such a design is expensive and time-consuming.

[0014] It was also proposed to modify the existing positioning methods to adapt them to the sub-assembly to be produced.

[0015] But again, such a design is expensive and time-consuming. Furthermore, positioning methods must be planned for each sub-assembly that might be produced.

[0016] Such solutions are all the less profitable as very few sub-assemblies are manufactured individually to form spare parts compared to the number of assemblies manufactured in series.

[0017] Such a manufacturing station is used in an assembly line manufacturing process. It is equipped with tools, in this case welding tools, carried by robotic arms that allow the elements to be quickly and automatically joined together.

[0018] Such an exhaust system assembly comprises several elements, the simplest of which are in the form of tubular pipes.

[0019] Modern exhaust systems also include several components with specific functions. For example, some components are equipped with exhaust gas treatment devices, such as particulate filters. As another example, in current vehicles, it is common practice to mix intake air with exhaust gases to reduce the production of pollutants during combustion. To achieve this, a component includes a recirculation valve designed to divert a portion of the exhaust gases into a recirculation circuit.

[0020] Such an exhaust system assembly most often features bends to adapt the geometry of the exhaust system assembly to the vehicle configuration.

[0021] In addition, some components of the exhaust line have an asymmetrical shape relative to the axis of gas flow in the duct.

[0022] Due to this particular geometry and the asymmetrical shape of each component, the entire exhaust system must be positioned very precisely in the manufacturing station to allow for precise welding of the various elements together.

[0023] To this end, the manufacturing station is equipped with positioning systems, such as those for orienting the assembly geometrically. These positioning systems use certain elements as geometric references. This allows the fastening tools to be automatically controlled to weld each assembly in series without operator intervention.

[0024] Document DE19549751 discloses a method and assembly station for the assembly and welding of vehicle exhaust systems, in which the entirety of several sub-assemblies is delivered pre-assembled to the manufacturing station, in a "complete" mode of use. BREF RESUME DE L'INVENTION

[0025] The present invention proposes a method of the type described above, allowing the manufacturing station to be reused without major modification, characterized in that, in a second mode of use called "partial" of the manufacturing station, only the sub-assembly is delivered pre-assembled to the manufacturing station, at least one jig being previously mounted on the pre-assembled sub-assembly to replace at least the missing complementary reference elements of the sub-assembly in order to allow the correct positioning of the sub-assembly on the processing station without modifying the positioning means of said station with respect to the "complete" mode of use.

[0026] According to other characteristics of the process: The jig is formed by an assembly of components fixed together, with all missing complementary elements being replaced by components of identical external shape; each jig is reusable for the manufacture of several identical sub-assemblies.

[0027] The invention also relates to a template for implementing the process carried out according to the teachings of the invention, characterized in that it comprises at least one component which is identical to the so-called "series" element used to manufacture an exhaust line assembly in the "complete" mode of use of the station.

[0028] According to other characteristics of the template: The jig includes at least one so-called "reinforced" component which has an external shape identical to the corresponding element used on the exhaust system assembly, but which has a more rigid internal structure; a complementary element of the assembly is formed by a tubular pipe, this tubular pipe being replaced by a component formed by a thicker-walled tubular pipe in the jig; the jig is intended to be fixed by axially fitting one of the jig's connecting ends with an end pipe of the sub-assembly; the jig is equipped with a tenon which is arranged at its axial connecting end, the tenon being intended to be inserted in a removable manner with a tight fit into the end pipe of the sub-assembly; the tenon includes a part for fixing with the connecting end of the jig;The fixing part is formed by a sleeve into which the connecting end of the template is inserted and fixed; the fixing part is formed by a dowel which is press-fitted into an axial hole in the connecting end of the template.

[0029] The invention also relates to a manufacturing station for at least a subset of elements of a motor vehicle exhaust line comprising tools for manufacturing said exhaust line and at least one jig. BREVE DESCRIPTION DES FIGURES

[0030] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the attached drawings in which: there figure 1 is a perspective view that represents an initial example of a set of elements forming part of an escapement line; the figure 2 is a perspective view that represents a set of elements positioned in a manufacturing station by positioning means; the figure 3 is an exploded perspective view that represents a subset of the whole of the figure 1 as well as a template made according to the principles of the invention; the figure 4 is an axial cross-sectional view that represents a temporary fixing tenon of the template of the figure 3 on the sub-assembly, the tenon being made according to a first embodiment of the invention; the figure 5 is a perspective view that represents a temporary fixing tenon of the template of the figure 3 on the sub-assembly, the tenon being made according to a second embodiment of the invention; the figure 6 is a view similar to that of the figure 1 which represents a second example of a set of piping components; the figure 7 is a view similar to that of the figure 3 which represents a subset of the whole of the figure 6 as well as two templates made according to the teachings of the invention. DESCRIPTION DETAILLEE DES FIGURES

[0031] In the following description, elements with an identical structure or analogous functions will be designated by the same reference.

[0032] In the following description, we will adopt an axial orientation directed locally along the axis of each element from upstream to downstream, according to the direction of flow of the exhaust gases intended to be evacuated by the exhaust line.

[0033] We represented at the figure 1 a set of 10 elements for an exhaust line (not shown) of a motor vehicle.

[0034] This assembly 10 comprises an exhaust duct delimited by a first upstream end 12 and by a second downstream end 14. The assembly 10 consists of an assembly of elements which will now be described from upstream to downstream.

[0035] A first element consists of a mounting flange 16, for example, on an exhaust manifold (not shown). This flange 16 is mounted at one upstream end of a second element formed by a flexible section 18. The flexible section 18 is itself connected to a third element formed by a rigid inlet pipe 20. The inlet pipe 20 supplies a fourth element, which is a pollution control device, here a particulate filter 22. An outlet of the particulate filter 22 is then connected to a fifth element formed by a rigid outlet pipe 24.

[0036] The outlet pipe 24 is connected to a series of several elements formed by rigid tubular pipes 26, hereafter referred to as intermediate pipes 26. These intermediate tubular pipes 26 form bends 28 of predetermined inclination. Each bend 28 extends in a plane that may differ from the other bends 28. A downstream end of the series of intermediate tubular pipes 26 is connected to an inlet port of an element formed by an exhaust silencer 30. An outlet port of the silencer 30 is connected to elements formed by a final series of tubular pipes 32 that terminate at the downstream port 14 of the exhaust pipe.

[0037] All these elements are connected in series to each other to form a single exhaust duct.

[0038] During production, such an assembly is delivered pre-assembled to a manufacturing station, for example, a welding station. This welding station includes at least one tool (not shown), in this case, a welding tool. The welding tool is carried by a robotic arm (not shown) which is automatically controlled by a welding program adapted to the geometry of assembly 10. For the automated welding to be sufficiently precise, it is preferable that the assembly 10 to be welded be positioned very accurately.

[0039] For this purpose, the welding station includes means 33 for positioning the assembly 10, as illustrated in the figure 2 These positioning devices use certain elements, called reference elements, as a geometric reference to precisely position and orient assembly 10 relative to the welding tool. Such positioning devices are designed specifically for the configuration of assembly 10.

[0040] The positioning means are for example formed by fixed supports equipped with means 35 for gripping the reference elements.

[0041] The manufacturing station can thus be used in a so-called "complete" operating mode to automatically weld all the elements of the set 10 together.

[0042] Furthermore, for the manufacture of spare parts, it sometimes happens that only a sub-assembly 34 of this assembly 10 needs to be manufactured. For example, in the event of a failure of the particulate filter 22, the entire assembly 10 will not be replaced. As shown in the figure 3 , only a sub-assembly 34 will be replaced, consisting of the fixing flange 16, the flexible section 18, the rigid inlet pipe 20, the particle filter 22 and the rigid outlet pipe 24.

[0043] It is advantageous to be able to fix the elements of this sub-assembly 34 using said welding station in a so-called "partial operating" mode using the same positioning means 33 as assembly 10.

[0044] However, set 10 includes elements, called "complementary elements", which are not part of subset 34. In the example shown in the figure 3 , the complementary elements are formed by the downstream rigid pipes 26 and their elbows 28, by the silencer 30 and by the last series of pipes 32.

[0045] However, some of these additional elements also serve as reference points for the welding station's positioning means. As a result, subassembly 34 cannot be correctly positioned on the positioning means 33. In the example shown in the figure 1 The additional reference elements here are formed by the 26 intermediate rigid pipes.

[0046] The invention proposes to deliver the pre-assembled sub-assembly 34 to the manufacturing station, at least one template 36 being previously mounted on the pre-assembled sub-assembly 34 to replace at least the missing complementary reference elements of the sub-assembly 34 in order to allow the correct positioning of the sub-assembly 34 on the manufacturing station without modifying the positioning means 33 of said station 34 with respect to its "complete" operating mode.

[0047] The robotic arm is then controlled by a program adapted to the fixing of the elements of sub-assembly 34. Thus, the robotic arm does not perform the welding operations of the additional elements replaced by the template 36.

[0048] As depicted in the figure 3 , the supplementary reference elements are replaced by a template 36 formed of components with an external shape identical to the corresponding supplementary reference elements.

[0049] In the example of the figure 2 , subassembly 34 is an upstream end section of assembly 10. A single template 36 is used to replace the missing downstream part to allow the positioning of subassembly 34.

[0050] Template 36 is reusable for the manufacture of several identical sub-assemblies 34.

[0051] The jig 36 is made up of an assembly of components whose external shape corresponds to that of the original elements they replace. These components are fixed to each other prior to the use of the jig 36. Thus, the jig 36 can be handled as a single element that is quickly and easily mounted on the sub-assembly 34.

[0052] However, some components replaced by those of template 36 are fragile and at risk of damage during repeated handling. Therefore, these fragile components are replaced on template 36 with so-called "reinforced" components. These reinforced components have an external shape identical to the corresponding component used on the exhaust system assembly 10, but this reinforced component has a different internal structure.

[0053] In the example shown in the figure 3 Each component 38 of the template corresponds to an intermediate tubular conduit 26. Each component 38 is made from a tubular conduit with a wall thicker than the corresponding intermediate tubular conduit 26 of the assembly 10. Thus, the template 36 can be handled with a reduced risk of deformation of the components 38 constituting it.

[0054] According to an unshown embodiment of the invention, other less fragile and more complex elements to reproduce are replaced by identical components on jig 36. At least one component of jig 36 is thus formed by a so-called "standard" element that is identical to the one used to manufacture the corresponding exhaust line assembly 10. For example, an exhaust gas recirculation valve present on the original assembly 10 can be reproduced by a standard element in jig 36 mounted on subassembly 34.

[0055] The template 36 is designed to be fixed by axially inserting a free connecting end 40 of the template 36 into a free end conduit 42 of the subassembly 34. For this purpose, the free connecting end of the template 34 is equipped with an axial tenon 44 arranged at its connecting end 40. The tenon 44 is designed to be inserted in a removable manner with a tight fit into the end conduit of the subassembly 34 to allow for its temporary fixing while the elements of the subassembly 34 are being welded together.

[0056] The tenon 44 is designed so that the template 36 is mounted on the subassembly 34 with sufficient precision to allow the template to optimally position the subassembly 34 on the positioning means 33.

[0057] The tenon 44 has a fixing part 46 with the connecting end 40 of the template 36.

[0058] According to a first embodiment which is represented in the figure 4 The tenon 44 fixing portion 46 is formed by an axial dowel which is fixed to the connecting end 40 of the template 36 by press fitting. For this purpose, the connecting end 40 of the template 36 is equipped with an axial orifice (not shown) which receives the dowel 46. The dowel 46 has an axial cylindrical shape which is extended axially by the tenon 44 so that the tenon 44 protrudes axially from the template 36 after the dowel 46 is fitted.

[0059] The tenon 44 has a free axial end with a generally conical shape to facilitate its axial insertion into the end opening of the subassembly 34. The tenon 44 has a radial dimension sufficient to allow the template 36 to be held fixed to the subassembly 34 by friction between the tenon 44 and an internal wall of the conduit during the welding operation in the welding station. However, the radial dimension of the tenon 44 allows the template 36 to be removed easily enough after the welding operation so as not to damage the subassembly 34.

[0060] This effect is obtained for example by equipping the tenon 44 with flats 48 which reduce the friction surface between the tenon 44 and the internal wall of the conduit of the subassembly.

[0061] According to a second embodiment of the invention, which is represented in the figure 5 The tenon 44 fixing part 46 is formed by a sleeve which is intended to be fitted with the connecting end 40 of the template 36. To allow a solid fixing between the template 36 and the sleeve 46, a threaded hole 50 is provided radially through a cylindrical wall of the sleeve 46. A clamping screw is intended to be screwed into this threaded hole 50 to secure the sleeve 46 to the template 36 by tightening the screw against a wall of the template 36, or by inserting one end of the screw into a corresponding hole in the template 36.

[0062] During the production of a subassembly 34, the elements constituting the subassembly 34 are assembled by interlocking. Then the template 36 is temporarily fixed to the subassembly 34 by removablely inserting the tenon 44 into the end hole of the subassembly 34.

[0063] The module formed by subassembly 34 and jig 36 is then positioned on the welding station's positioning means 33. The welding arm is then controlled to weld the elements of subassembly 34 together using a suitable control program.

[0064] At the end of the welding operation, the sub-assembly 34 and the template 36 are removed from the positioning means 33, then the template 36 is removed, by unclipping, from the sub-assembly 34 thus fixed.

[0065] According to a variant of the invention which is represented in the figure 6 The assembly 10 does not include a particulate filter, but an exhaust gas recirculation valve 52 which is arranged on an intermediate portion of the assembly 10. The recirculation valve 52 is connected to an upstream pipe 54, on the one hand, and to a downstream pipe 56, on the other hand.

[0066] The intermediate situation of subassembly 34 comprising the upstream pipe 54, the recirculation valve 52 and the downstream pipe 56 requires the use of two templates 36A, 36B. An upstream template 36A is connected to an upstream free end of subassembly 34 via a tenon 44A, while a downstream template 36B is connected to a downstream free end of subassembly 34 via a tenon 44B.

[0067] In this example, the upstream template 36A is made up of an assembly of components identical to the standard elements of the original set 10, while the downstream template 36B is made up of an assembly of "reinforced" components.

[0068] The process carried out according to the teachings of the invention thus makes it possible to manufacture sub-assemblies 34 with the same means of production as the complete assembly 10.

[0069] In addition, the 36, 36A, 36B templates used to implement this process are advantageously manufactured from standard parts to reduce manufacturing costs.

[0070] In addition, some components of the jig are made of "reinforced" elements to allow their repeated use during the mass production of sub-assemblies 34 by reusing the same jig.

[0071] Furthermore, the same positioning devices are used for the production of complete assemblies and for the individual production of sub-assemblies. By avoiding the manufacture of specific positioning devices for each sub-assembly, material storage space and maintenance time are saved.

Claims

1. Method for individually manufacturing a subassembly (34) of motor vehicle exhaust line elements on a production work station, the subassembly (34) being intended to be connected to other elements to form an exhaust line assembly (10), at least one complementary element of the assembly (10) not forming part of the said subassembly (34), in a first mode of use of the manufacturing work station, referred to as "complete", all the elements of the assembly (10) are delivered to the manufacturing work station preassembled, at least one complementary element, referred to as reference element, forming a geometric reference to allow positioning means (33) belonging to the work station to position the assembly (10) with respect to tools of the work station, in a second mode of use of the manufacturing work station referred to as "partial", only the subassembly (34) is delivered to the manufacturing work station, preassembled, characterized in that at least one jig (36) is premounted on the preassembled subassembly (34) to replace at least the complementary reference elements missing from the subassembly (34) so that the subassembly (34) can be correctly positioned on the processing work station without modifying the positioning means (33) of the said work station by comparison with the "complete" mode of use.

2. Method according to the preceding claim, characterized in that the jig (36) is formed by an assembly of components fixed together, all the missing complementary elements being replaced by components (38) of identical exterior shape.

3. Method according to either one of the preceding claims, characterized in that each jig (36) is reused for the manufacture of several identical subassemblies (34).

4. Jig (36) for implementing the method according to any one of the preceding claims, characterized in that it comprises at least one component (38) which is identical to a "series-production" pipework element used to manufacture an exhaust line assembly in a "complete" mode of use of the work station.

5. Jig (36) according to the preceding claim, characterized in that it comprises at least one so-called "reinforced" component which has an exterior shape identical to the corresponding element used on the exhaust line assembly (10) but which has a more rigid internal structure.

6. Jig (36) according to the preceding claim, characterized in that a complementary element of the assembly is formed by a tubular pipe (26), this tubular pipe (26) being replaced by a component (38) formed by a tubular pipe with greater wall thickness in the jig (36).

7. Jig (36) according to any one of the preceding claims, characterized in that it is intended to be fixed by axial insertion of a connection end (40) of the jig (36) into an end pipe of the subassembly (34) .

8. Jig (36) according to the preceding claim, characterized in that the jig (36) is equipped with a tenon (44) which is arranged at its axial connection end (40), the tenon (44) being intended to be plugged removably in with a snug fit into the end pipe of the subassembly (34).

9. Jig (36) according to the preceding claim, characterized in that the tenon (44) comprises a part (46) for fixing to the connection end (40) of the jig (36).

10. Jig (36) according to the preceding claim, characterized in that the fixing part (46) is formed by a sleeve into which the connection end (40) of the jig (36) is inserted and secured.

11. Jig (36) according to Claim 9, characterized in that the fixing part (46) is formed by a peg which is driven forcibly into an axial orifice at the connection end (40) of the jig (36).

12. Work station for manufacturing at least one subassembly (34) of motor vehicle exhaust line elements, characterized in that it comprises tools for manufacturing the said exhaust line and at least one jig according to one of Claims 4 to 11.