Welding structure of warm-up catalytic converter

A welding structure for a warm-up catalytic converter (WCC) of a vehicle includes a flange of a turbine housing connected to a front cone of the WCC which reduces an exhaust gas emitted from an engine. A through hole is formed in the flange, through which the exhaust gas flows. An extending portion, which extends in a direction in which the exhaust gas flows from the through hole, is formed and surface-contacts the front cone. The front cone is welded to the extending portion to connect the flange to the front cone.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Korean Patent Application No. 10-2014-0147454, filed on Oct. 28, 2014, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a welding structure of a warm-up catalytic converter (WCC), and more particularly, to a welding structure of a WCC in which a front cone of the WCC is welded to a flange of a turbine housing.

BACKGROUND

A warm-up catalytic converter (WCC)of a vehicle purifies exhaust gas emitted from a vehicle engine has an inlet portion welded to a turbine housing.

As illustrated inFIGS. 1 and 3, a flange101of a turbine housing is welded to inlet portions of front cones102and102′ of a WCC, such that exhaust gas emitted from a turbine of the turbocharger enters the WCC.

A method for welding the front cones102and102′ to the flange101can be divided into an inner peripheral welding method as illustrated inFIGS. 1 and 2and an outer peripheral welding method as illustrated inFIGS. 3 and 4.

The inner peripheral welding method fixes the front cone102to the flange101by inserting the inlet portion of the front cone102into a through hole formed in the flange101and then welding the front cone102to the flange101within the through hole. The inner peripheral welding method is made when an interval G1between the flange101and an outer peripheral surface of the front cone102is narrow, and thus, a welding tool may not enter into the interval therebetween. As a result, the exhaust system can be minimized A catalyst may be activated in the early stage by improving dynamic stiffness, improvement in noise, vibration, and harshness (NVH), and shortening an exhaust passage due to the small size of the exhaust system. However, as a welded portion103is directly exposed to a high-temperature exhaust gas, contraction and expansion stress may apply to the flange101, thus decreasing durability against thermal fatigue.

In the outer peripheral welding method, the inlet portion of the front cone102′ is inserted into the through hole of the flange101and then welding is applied at which an outer peripheral surface of the front cone102′ meets the flange101. The outer peripheral welding method can reduce an exposure temperature and disperse the contraction and expansion stress due to the welded portion103formed at outside the exhaust passage, but may reduce a catalyst capacity and may deteriorate the dynamic stiffness and the NVH due to an increase in sizes of the exhaust passage and the front cone102′.

SUMMARY

An aspect of the present inventive concept provides a welding structure for a WCC of a vehicle capable of dispersing a stress concentration of a welded portion and increasing durability against thermal fatigue by welding a front cone of the catalytic converter to a flange of a turbine housing in a state in which the flange surface-contacts the welded portion of the front cone.

Another aspect of the present inventive concept provides a welding structure for a WCC of a vehicle capable of improving weldabiltiy by making a thickness of a welded portion of a front cone in an inner circumference of the front cone thinner than a thickness of a main body of a flange.

Still another aspect of the present inventive concept provides a welding structure for a WCC of a vehicle capable of minimizing an exposure to a high-temperature exhaust gas due to a welded portion of a front cone formed in back of a portion extending from the flange.

Other objects and advantages of the present disclosure can be understood by the following description, and become apparent with reference to the embodiments of the present inventive concept. In addition, it is obvious to those skilled in the art to which the present invention pertains that the objects and advantages of the present invention can be realized by the means as claimed and combinations thereof.

In accordance with an embodiment of the present inventive concept, a welding structure for a warm-up catalytic converter (WCC) of a vehicle includes a flange of a turbine housing connected to a front cone of the WCC which reduces an exhaust gas emitted from an engine. A through hole is formed in the flange, through which the exhaust gas flows. An extending portion, which extends in a direction in which the exhaust gas flows from the through hole, is formed and surface-contacts the front cone. The front cone is welded to the extending portion to connect the flange to the front cone.

The extending portion may include an inner peripheral extending portion which extends from the through hole and contacts an inner peripheral surface of the front cone. The inner peripheral extending portion may be welded to the front cone.

An end of the inner peripheral extending portion may be welded to the inner peripheral surface of the front cone.

An end of an outer peripheral surface of the front cone may be welded to the flange.

A thickness of the inner peripheral extending part may be thinner than that of the flange.

The extending portion may further include an outer peripheral extending portion which extends from the through hole and contacts an outer peripheral surface of the front cone. The outer peripheral extending portion may be welded to the front cone.

An end of the outer peripheral extending portion may be welded to the outer peripheral surface of the front cone.

A thickness of the outer peripheral extending part may be formed to be thinner than that of the flange.

The front cone may be formed of a stainless steel material.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Hereinafter, a welding structure for a WCC of a vehicle in accordance with exemplary embodiments of the present inventive concept will be described in detail with reference to the accompanying drawings.

As illustrated in detail inFIGS. 5 to 7, in a welding structure of an inlet portion of a WCC of a vehicle in accordance with an exemplary embodiment of the present inventive concept, a flange11is mounted to a turbine housing10and connected to a front cone12of a WCC which reduces exhaust gas emitted from an engine. A through hole11cis formed in the flange11to make the exhaust gas flow therethrough. An extending portion extends in a direction in which the exhaust gas flows at which the through hole11cof the flange11is formed and surface-contacts the front cone12which is welded to the extending portion to connect the flange11to the front cone12.

The through hole11cis a passage formed in the flange11to emit the exhaust gas from the turbine housing side therethrough. An inner peripheral extending portion11aextends in a direction in which the exhaust gas flows from the through hole11c, that is, in a connection direction of the front cone12. The inner peripheral extending portion11aextends in a direction in which the exhaust gas flows from the through hole11cof the flange11, that is, to the front cone12by a predefined length, and contacts an inner peripheral surface of the front cone12, that is, an inside circumference.

The front cone12is inserted into an outside of the inner peripheral extending portion11a, and thus, the flange11and the front cone12overlap each other by the extending length of the inner peripheral extending portion11a.

The flange11and the front cone12are fixed to each other by welding. That is, the inner peripheral extending portion11aof the flange11and the inner peripheral surface of the front cone12are welded to each other. In this case, the inner peripheral surface of the front cone12is welded to an end of the inner peripheral extending portion11a. Referring toFIGS. 6 and 7, the inner peripheral surface of the front cone12is welded to the inner peripheral extending portion11a at the end of the inner peripheral extending portion11ato form an inner welding portion13a.

A thickness of the inner peripheral extending portion11amay be thinner than that of the flange11.

An outer peripheral surface of the front cone12is directly welded to a main body of the flange11at an end thereof. The outer peripheral surface of the front cone12is welded to the main body of the flange11to form an outer welding portion13b.

Here, a material of the front cone12may be stainless steel which is lighter and higher durability and workability than the commonly used cast steel material.

As described above, when the inner peripheral surface of the front cone12is welded to the end of the inner peripheral extending portion11awhich extends from the flange11to the inner peripheral surface of the front cone12, as illustrated inFIG. 6, the inner welding portion13ais formed at a lower portion of the front cone12in the flow direction of the exhaust gas, and therefore, exposure to a high-temperature exhaust gas can be minimized

Further, the thickness of the inner peripheral extending portion11ais thinner than that of the flange11, and therefore, weldabiltiy is excellent and the durability of the welded portion is improved.

FIG. 7illustrates a thermal stress distribution at the connection portion of the flange11and the front cone12. There, the inner peripheral surface of the front cone12is applied with the thermal expansion stress from the inner peripheral extending portion11aand the inner welding portion13aand is applied with the thermal contraction stress from the outer welding portion13b. The thermal expansion stress is dispersed at the inner peripheral surface of the front cone12as much as the extending length of the inner peripheral extending portion11a, and therefore, durability against thermal fatigue increases.

FIGS. 8 to 10illustrate a welding structure of an inlet portion of a WCC of a vehicle in accordance with another exemplary embodiment of the present inventive concept.

In accordance with another exemplary embodiment of the present inventive concept, in addition to the components of the foregoing exemplary embodiment, an outer peripheral extending portion11b, which extends from the flange11and contacts the outer peripheral surface of the front cone12, is additionally formed.

The outer peripheral extending portion11bis formed in a direction in which the exhaust gas flows from the flange11, that is, the same direction as the inner peripheral extending portion11a.

Likewise the inner peripheral extending portion11a, the outer peripheral extending portion11bhas a thickness thinner than that of the flange11.

The front cone12is inserted between the inner peripheral extending portion11aand the outer peripheral extending portion11b, and the front cone12is welded to the inner peripheral extending portion11aand the outer peripheral extending portion11b. That is, as illustrated in an inner peripheral surface and an outer peripheral surface of the front cone12are each welded to ends of the inner peripheral extending portion11aand the outer peripheral extending portion11b.

In accordance with another exemplary embodiment of the present inventive concept, the ends of the inner peripheral extending portion11aand the outer peripheral extending portion11bwhich extend from the flange11to the inner peripheral surface and the outer peripheral surface of the front cone12are each welded to the inner peripheral surface and the outer peripheral surface of the front cone12. Therefore, the inner welding portion13aand the outer welding portion13bare formed at a downstream in the flow direction of the exhaust gas, thereby minimizing exposure to the exhaust gas. Further, the thickness of the outer peripheral extending portion11bis thinner than that of the flange11, and therefore, weldabiltiy is excellent and durability of the welded portion is improved.

FIG. 10illustrates a thermal stress distribution at the connection portion of the flange11and the front cone12. Here, the inner peripheral surface of the front cone12is applied with thermal expansion stress through the overall length of the inner peripheral extending part11aand the inner welding part13a, and the outer welding part13band the outer peripheral surface of the front cone12is applied with thermal contraction stress from the outer welding portion13b, thereby increasing durability against thermal fatigue.

According to the welding structure of the inlet portion of the WCC in accordance with the exemplary embodiments of the present inventive concept as described above, it is possible to increase durability against thermal fatigue by delivering the thermal stress generated at the time of thermal expansion of the flange due to the flow of a high-temperature exhaust gas from the inner peripheral extending portion and the outer peripheral extending portion to the front cone, by welding the front cone to the inner peripheral extending portion and the outer peripheral extending portion in which the front cone of the WCC and the flange of the turbine housing surface-contact the peripheral extending portion and the outer peripheral extending portion which extend from the flange.

Further, it is possible to improve weldability of the welded portion by making the thickness of the inner peripheral extending portion and the outer peripheral extending portion thinner than that of the flange, thereby increasing durability of the welded portion.

In addition, it is possible to minimize exposure of the welded portion to the high-temperature exhaust gas when the high-temperature exhaust gas flows due to the inner peripheral extending portion formed at a lower portion of the inner peripheral extending portion.

The foregoing exemplary embodiments are only examples to allow a person having ordinary skill in the art to which the present invention pertains to easily practice the present disclosure. Accordingly, the present disclosure is not limited to the foregoing exemplary embodiments and the accompanying drawings, and therefore, a scope of the present disclosure is not limited to the foregoing exemplary embodiments. Accordingly, it will be apparent to those skilled in the art that substitutions, modifications, and variations can be made without departing from the spirit and scope of the disclosure as defined by the appended claims and can also belong to the scope of the present disclosure.