FIELD OF THE INVENTION

The present invention relates to the process and method of manufacturing a turbocharger, more particularly, it relates to an improved process and method of manufacturing a variable turbine geometry (VTG) cartridge with negligible rejection rate.

BACKGROUND OF THE INVENTION

Turbocharger is a turbine driven forced induction device used in combination with internal combustion engine for increasing the power output of the engine. Turbocharger delivers compressed air to the intake of the internal combustion engine to be mixed with fuel and burned in the engine allowing more fuel to be combusted, thus boosting the power output of the engine without increasing the engine weight. Major use of turbochargers includes Passenger Car, Commercial vehicles, train, aircraft, construction equipment engines, industrial and marine applications. To meet the global emission norms and performance expectations, various designs of turbochargers have been introduced in the market by the global-Turbo manufacturers.

A Variable Turbine Geometry (VTG) Turbocharger is one such design which was developed to meet the desired requirements of the industry that works with both diesel and gasoline engines. In general, process of assembling the parts of VTG for manufacturing the cartridges comprises of: welding of plurality of vanes and levers on to the vane ring; welding the plurality of adjuster pin on the adjusting ring; loading the adjusting ring on to the vane ring, this resulting sub assembly is termed as vane ring assembly; welding a plurality of minimum flow stop pin to the assembly; combining the vane ring assembly with pre guide blade ring and discs to form the VTG cartridge; and subjecting the entire cartridge assembly to minimum flow check process. After the checking process around 6% of the VTG cartridges are rejected for defective setting and improper performance. Even after subjecting the defective cartridge assemblies for rework to correct the min flow values the rejection rate is not eliminated. Therefore, there is a need in art for an improved process for the production of VTG cartridges with nil rejection rate due to improper performance during the minimum flow check process.

IN5115/DELNP/2009 discloses a method for manufacturing a variable-vane cartridge mechanism for a turbocharger comprising of a nozzle ring, an insert that engages a turbine housing bore, and a plurality of spacers. Holes larger in diameter than the spacers are formed in the nozzle ring and a nozzle portion of the insert, such that the spacers fit loosely in the holes. A locating fixture is engaged with the nozzle ring and insert for precisely locating these parts radially with respect to each other; the spacers can move within the holes as needed to allow the positions of the parts to be adjusted. Once located relative to each other, the nozzle ring and insert are fixed in the desired relative positions by affixing the spacers to them, such as by welding.

IN1102/KOL/2005 provides a turbocharger of variable turbine geometry, comprising: a vane bearing ring assembly including a vane bearing ring and a disk which can-be fixed to the vane bearing ring for creating a flow channel; and at least one support pin which is connected with a first end to the vane bearing ring and which is welded with a second end to the disk which comprises recesses for the support pin end to be welded, the recesses being surrounded by a heat throttle.

US9308576 discloses a method of manufacturing a turbocharger with variable turbine geometry having a turbine housing with a feed duct for exhaust gases; a turbine rotor which is rotatably mounted in the turbine housing; and a guide grate which surrounds the turbine rotor radially at the outside, which has a blade bearing ring, which has a multiplicity of guide blades, which have in each case one blade shaft mounted in the blade bearing ring, which has an adjusting ring operatively connected to the guide blades via associated blade levers fastened to the blade shafts at one of the ends thereof, each blade lever having at the other end a lever head which can be placed in engagement with an associated engagement recess of the adjusting ring, and which has a stop at least for setting the minimum through flow through the nozzle cross sections formed by the guide blades. The stop is formed as a setting pin which is fastened by means of an automated butt welding process, the position of the setting pin being determined from a previously carried out throughflow measurement with similar guide grates. US14396118 discloses an exhaust-gas turbocharger having a turbine, which has a turbine wheel surrounded by an intake duct, and having a VTG cartridge, which has a washer and a vane bearing ring, which delimit the intake duct, and which has a plurality of vanes, which are arranged in the intake duct and are mounted in the vane bearing ring by way of rotatable vane shafts, which are connected to vane levers, the lever heads of which engage into associated grooves in a unison ring, which surrounds the vane bearing ring on the outside, and which has a radial bearing between the vane bearing ring and the unison ring, wherein the radial bearing has at least one pin, which is fixed on the vane bearing ring and onto which a rolling roller is placed, against which an inner wall region of the unison ring bears. US12279702 provides a blade bearing ring assembly of a turbocharger with a variable turbine geometry, Wherein the said turbocharger comprises a blade bearing ring assembly with a blade bearing ring and a disc, which can be fixed to the blade bearing ring to create a flow channel and also comprises at least one bearing pin, one first end of which is connected to the blade bearing ring and the second end of which is connected to the disc. Both ends of the bearing pin are butt welded to the blade bearing ring and the disc.

All of the above said methods of manufacturing or assembling of a turbocharger cartridges boast a challenge to the manufacturer in terms of attaining a lower rejection rate in the production line. The high rejection rate of around 6 % during VTG cartridges production is due the non-precise positioning of the minimum flow stopping pins. The present invention eliminates the said problem by determining the precise position of the setting pin from a realtime through flow measurement carried out on the actual VTG cartridge. The present invention by adopting the said method produces VTG cartridges with near zero rejection rate. Further the present invention eliminates the need of secondary welding on the assembled VTG cartridge and also eliminates the need of reworking on the defective cartridges. OBJECTIVE OF THE INVENTION

The main objective of the present invention is to provide an improved process and method for manufacturing a Variable Turbine Geometry (VTG) Turbocharger with minimum rejection rate. Another objective of the present invention is to reduce the rejection rate to 0% by employing optimized process steps for the VTG cartridge assembly process.

It is still another objective of the present invention is to eliminate the secondary welding of the assembled cartridges. BRIEF DESCRIPTION OF DRAWING:

Figure 1 depicts the Variable Turbine Geometry (VTG) Turbocharger cartridge assembly.

Figure 2 shows the cartridge with radial maximum flow direction.

Figure 3 shows the cartridge with radial minimum flow direction.

Figure 4 depicts the cartridge positioned in a turbine. Figure 5 shows the process steps in positioning the pins on the cartridge.

While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

SUMMARY

The present invention provides an improved process method of manufacturing of a variable turbine geometry (VTG) turbocharger cartridges (100) with near zero rejection rate, comprising of: an adjuster ring (101 ); an adjuster pin (201 ) fastened on the adjuster ring (101); a vane bearing ring (103) with plurality of vanes (104) and levers (106) operatively connected to the adjuster ring (101), resulting in a vane ring assembly; a pre-guide blade ring assembly (108) added to the said vane ring assembly to form the assembled VTG cartridge; and at least a set of stopper pins (107a, 107b) for setting a minimum through flow through nozzle cross sections formed by the vanes, wherein the position of setting the stopper pins (107a, 107b) is being determined from the real-time minimum through flow measurement on the actual VTG cartridge assembly; a plurality of stop pins (107a, 107b) is fastened on the vane bearing ring (103) oriented with the servo drives, at the determined position and angle; and finally subjecting the fully assembled VTG cartridges with welded stop pins (107a, 107b) to final minimum flow check process, to guarantee the minimum through flow measurement is within the specified limit, resulting in near zero rejection rate in the production line. The present invention produces VTG cartridges with near zero rejection rate, thereby eliminating the need of secondary welding on the assembled VTG cartridge. The said method saves enormous amount of time and effort associated with the rework of the rejected cartridges. Further the present invention, increases the productivity and minimizes the losses incurred due to the rejection of defective VTG cartridge. DETAILED DESCRIPTION OF THE INVENTION:

The present invention as embodied by an improved method of manufacturing a variable turbine geometry cartridge, succinctly fulfils the above-mentioned need(s) in the art. The present invention has objective(s) arising as a result of the above-mentioned need(s), said objective(s) being enumerated below. In as much as the objective(s) of the present invention are enumerated, it will be obvious to a person skilled in the art that, the enumerated objective(s) are not exhaustive of the present invention in its entirety, and are enclosed solely for the purpose of illustration. Further, the present invention encloses within its scope and purview, any structural alternative(s) and/or any functional equivalent(s) even though, such structural alternative(s) and/or any functional equivalent(s) are not mentioned explicitly herein or elsewhere, in the present disclosure. The present invention therefore encompasses also, any improvisation(s)/modification(s) applied to the structural alternative(s)/functional alternative(s) within its scope and purview. The present invention may be embodied in other specific form(s) without departing from the spirit or essential attributes thereof.

Throughout this specification, the use of the word "comprise" and variations such as "comprises" and "comprising" may imply the inclusion of an element or elements not specifically recited.

The present invention provides an improved process method of manufacturing of a variable turbine geometry (VTG) turbocharger cartridges (100) with near zero rejection rate, comprising of: an adjuster ring (101), with a plurality of recess (102) and grooves (111); an adjuster pin (201) fastened at appropriate location on the adjuster ring (101 ); a vane bearing ring (103) with plurality of vanes (104) and levers (106) operatively connected to the adjuster ring (101), wherein the said assembly is the vane ring assembly, wherein one end of each of the vanes (104) is provided with a blade shaft (105) mounted in the vane bearing ring (103), wherein first end of the lever (106) is fastened at a plurality of recess (102) at the adjuster ring (101) by means of a lever head (109) and the second end of the lever (106) is affixed to the said blade shaft (105) by means of an appropriate aperture (110); at-least a drive hole (202) on the said vane bearing ring (103) to engage at-least a servo drive; a pre-guide blade ring assembly (108) added to the said vane ring assembly to form the assembled VTG cartridge; and at least a set of stopper pins (107a, 107b) for setting the minimum through flow through nozzle cross sections formed by the vanes, wherein the position of setting the stopper pins (107a, 107b) is being determined from the real-time minimum flow measurement on the actual VTG cartridge assembly.

In the preferred embodiment, wherein the said adjuster pin (201) is fastened to the adjuster ring (101 ) by means of a capacitor discharge welding process.

In the preferred embodiment, wherein the said first end and the second end of the plurality of levers (106) are fastened to the plurality of recess (102) on the adjuster ring (101 ) and blade shaft (105) respectively by means of a plasma welding process.

In an embodiment of the present invention, Fig 5 shows the process of determining the position and angle of the stopper pins (107a, 107b) on the assembled VTG cartridge, comprises of :a) subjecting the assembled VTG cartridge with the servo drive to minimum flow test measurement on the flow test rig, wherein the said vahes (104) are set to operate in close condition direction and the adjuster ring (101) is made to end the rotating movement (301) at the required minimum flow set value through CNC servo drive; b) deriving the position and angle of plurality of the stopper pins (107a, 107b) for the minimum flow with servo drive engaged onto the said drive hole (202); c) uploading the identified setting position of the stopper pins to the process control station; d) positioning the assembled VTG cartridge oriented with the servo drives for fastening the plurality of stoppers pins (107a, 107b); e) fastening the plurality of stopper pins (107a , 107b) on the vane bearing ring (103) oriented with the servo drives on the said drive hole (202), at the determined position and angle in precision with the measured minimum through flow value.

In the preferred embodiment of the present invention, wherein the stopper pins (107a, 107b) are fastened on the vane bearing ring (103) by means of capacitor discharge welding process.

In an embodiment of the present invention, the full assembled VTG cartridge with welded stopper pins is passed through the minimum flow check process, wherein the vanes(104) are operated to close condition direction and the adjuster ring (101) made to end the rotating movement (301) at stopper pins (107a, 107b) and the minimum through flow is measured. If the min through flow value is within the specified limit, the VTG cartridge assembly is passed as accepted.

In the present invention, the said stopper pins (107a, 107b) are welded in the identified position determined through the actual minimum through flow measurement of the VTG cartridge assembly, thus the cartridge assembly pass through the minimum flow check process without any rejection. This eliminates the need of secondary welding on the assembled VGT cartridge. By achieving 0% rejection rate, the said improved method of manufacturing VTG cartridge saves enormous amount of time and effort associated with the rework and other deviations of the rejected VTG cartridges. Further the present invention, increases the productivity and minimizes the losses incurred due to the rejection of the defective VTG cartridge.