阅读说明：本技术 耦合式扭力梁车桥的扭力梁 (Torsion beam of coupling type torsion beam axle ) 是由 宋志恩 姜熙坤 姜文远 于 2020-10-14 设计创作，主要内容包括：本发明涉及一种耦合式扭力梁车桥的扭力梁,其可以包括：外梁,所述外梁具有其中所述外梁的端部部分的中间部的外突出部形成为在所述外梁的纵向方向上朝向上方突出的第一截面,并且外裙部在所述外突出部的两个端部部分处沿着纵向方向竖直延伸；以及内梁,其具有其中所述内梁中的端部部分的中间部的内突出部插入到所述外梁中以面对所述外梁的所述外突出部的第二截面,并且内裙部在所述内突出部的两个端部部分处竖直延伸,并且所述内裙部的每个外表面和所述外裙部的每个内表面以相互匹配的状态表面结合。在所述内突出部的外表面与所述外突出部的内表面之间形成有间隙,以形成闭合截面。(The invention relates to a torsion beam of a coupled torsion beam axle, which can comprise: an outer beam having a first section in which an outer protrusion of an intermediate portion of an end portion of the outer beam is formed to protrude upward in a longitudinal direction of the outer beam, and an outer skirt extends vertically in the longitudinal direction at both end portions of the outer protrusion; and an inner beam having a second section in which an inner protrusion of a middle portion of an end portion in the inner beam is inserted into the outer beam to face the outer protrusion of the outer beam, and an inner skirt vertically extends at both end portions of the inner protrusion, and each outer surface of the inner skirt and each inner surface of the outer skirt are surface-bonded in a mutually matched state. A gap is formed between an outer surface of the inner protrusion and an inner surface of the outer protrusion to form a closed cross-section.)

1. A torsion beam of a coupled torsion beam axle, the torsion beam comprising:

an outer beam having a first cross section in which an outer protrusion of an intermediate portion of an end portion of the outer beam is formed as a first cross section protruding upward in a longitudinal direction of the outer beam, and an outer skirt extends vertically in the longitudinal direction at a first end portion and a second end portion of the outer protrusion; and

an inner beam having a second cross section in which an inner protrusion of a middle portion of an end portion in the inner beam is inserted into the outer beam to face the outer protrusion of the outer beam, and an inner skirt vertically extends at first and second end portions of the inner protrusion, each outer surface of the inner skirt and each inner surface of the outer skirt being surface-bonded in a mutually mated state,

wherein a gap is formed between an outer surface of the inner protrusion and an inner surface of the outer protrusion to form a closed cross-section between the outer surface of the inner protrusion and the inner surface of the outer protrusion.

2. The torsion beam of the coupled torsion beam axle according to claim 1, wherein the weld-bonding is performed linearly along each end portion of the inner skirt and each inner surface of the outer skirt that contacts each end portion of the inner skirt.

3. The torsion beam of the coupled torsion beam axle of claim 1, wherein each outer surface of the inner skirt and each inner surface of the outer skirt are locally welded in a longitudinal direction.

4. The torsion beam of the coupled torsion beam axle according to claim 3, wherein each outer surface of the inner skirt and each inner surface of the outer skirt are welded at predetermined intervals in a longitudinal direction of the inner skirt and the outer skirt.

5. The torsion beam of the coupled torsion beam axle according to claim 3, wherein each outer surface of the inner skirt and each inner surface of the outer skirt are welded to upper and lower portions of the outer skirt and the inner skirt at predetermined intervals in a longitudinal direction of the inner skirt and a longitudinal direction of the outer skirt, and joined such that welding positions of the upper and lower portions are offset from each other.

6. The torsion beam of the coupled torsion beam axle of claim 5, wherein upper and lower portions of the outer skirt and the inner skirt are joined in a zigzag order in the upper and lower portions.

7. The torsion beam of the coupled torsion beam axle according to claim 3, wherein each outer surface of the inner skirt and each inner surface of the outer skirt are welded in a longitudinal direction of the inner skirt and the outer skirt, and are combined such that a welding range of a center portion of the torsion beam is longer than other welding ranges on first and second end sides of the center portion of the torsion beam.

8. The torsion beam of the coupled torsion beam axle according to claim 3, wherein each outer surface of the inner skirt and each inner surface of the outer skirt are welded in a longitudinal direction of the inner skirt and the outer skirt, and are not welded at a center portion of the torsion beam but are welded at first and second end sides of the center portion of the torsion beam.

9. The torsion beam of the coupled torsion beam axle of claim 1, wherein the gap is formed by offsetting a cross-section of the inner protrusion to a shape corresponding to a cross-section of the outer protrusion.

10. The torsion beam of the coupled torsion beam axle of claim 1, wherein the gap is formed between an entire outer surface portion of the inner protrusion and an entire inner surface portion of the outer protrusion.

11. The torsion beam of the coupled torsion beam axle of claim 1, wherein a front surface of each outer surface of the inner skirt is in contact with each inner surface of the outer skirt.

12. The torsion beam of the coupled torsion beam axle according to claim 1, wherein a concave curvature whose curvature direction changes toward the inner side of the inner beam is formed at a position where an outer surface of the inner protrusion is connected with each outer surface of the inner skirt.

13. The torsion beam of the coupled torsion beam axle of claim 1,

wherein the outer beam and the inner beam are formed at their central portions with the same section portion formed by maintaining a closed section of the same shape,

variable cross-sectional portions formed by changing the shape of a closed cross-section are formed at the first end side and the second end side of the same cross-sectional portion.

14. The torsion beam of the coupled torsion beam axle of claim 13, wherein the variable cross-section portion comprises:

a first variable portion, wherein a first side of the first variable portion is connected to a side of the same section portion, and an upper end portion of the inner beam is inclined downward to increase a vertical height of the closed section;

a second variable portion, wherein a first side of the second variable portion is connected to a second side of the first variable portion, an upper end portion of the outer beam and an upper end portion of the inner beam are formed in a horizontal sectional shape having a width of a predetermined length or more, and the second side of the second variable portion is connected to a side surface of the trailing arm.

15. The torsion beam of the coupled torsion beam axle of claim 14,

wherein end portions of the outer beam and the inner beam are formed in a shape surrounding a part of side surfaces of the trailing arms,

an upper end portion of the outer beam is joined to an upper surface of the trailing arm,

an upper end portion of the inner beam is joined to a bottom surface of the trailing arm.

16. The torsion beam of the coupled torsion beam axle according to claim 13, wherein a clamp hole is formed in the variable cross-sectional portion adjacent to the same cross-sectional portion of the upper end portion of the outer beam.

17. The torsion beam of the coupled torsion beam axle according to claim 16, wherein a receiving surface is formed on an upper end portion of the inner beam facing the clamp hole in a direction perpendicular to an axial direction of the clamp hole.

Technical Field

The present invention relates to a torsion beam of a coupled torsion beam axle (coupled torsion beam axle), which satisfies durability performance without increasing the weight of components by structural improvement of the torsion beam.

Background

A suspension of a vehicle is a device that prevents damage to a vehicle body or goods and improves ride comfort by connecting an axle and the vehicle body to prevent vibration or impact received from a road surface from being directly transmitted to the vehicle body while driving, and is divided into a front suspension and a rear suspension.

As rear suspensions for light and medium-sized passenger vehicles, Coupled Torsion Beam Axles (CTBA) are used, which exhibit high driving stability compared to lower unit cost and mass.

When the vehicle body pitches (pitching) during traveling, the coupled torsion beam axle absorbs the pitching by the torsional elasticity of the members.

Further, when the vehicle is running in a curve, a displacement difference is generated between the left and right wheels according to the roll characteristic of the vehicle, and the torsion bar as the intermediate member of the axle is twisted, thereby improving the roll rigidity. Thus, the coupled torsion beam axle is configured to ensure rotational stability.

High-performance vehicles can ensure a rapid response capability in terms of handling because of their high roll stiffness characteristics, and high-stiffness coupled torsion beam axles are indispensable in medium-and small-sized high-performance vehicles because they are applied to the rear wheels.

However, the high stiffness coupled torsion beam axle has the following problems: as the input load increases, the durability/strength performance decreases, and a side effect of increasing the weight of the component is generated when the component is added to increase the rigidity. Accordingly, there is a need for a lightweight, high stiffness coupled torsion beam axle structure that can meet durability performance without significantly increasing the weight of the components.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Disclosure of Invention

Various aspects of the present invention are directed to provide a torsion beam of a coupled torsion beam axle, which satisfies durability performance without increasing the weight of components through structural improvement of the torsion beam.

According to various exemplary embodiments of the present invention, a torsion beam of a coupled torsion beam axle includes: an outer beam having a first cross section in which an outer protrusion of an intermediate portion of an end portion of the outer beam is formed to protrude upward in a longitudinal direction of the outer beam, and outer skirts vertically extend in the longitudinal direction at both end portions of the outer protrusion; and an inner beam having a second section in which an inner protrusion of a middle portion of an end portion in the inner beam is inserted into the outer beam to face the outer protrusion of the outer beam, and inner skirts extend in a vertical direction at both end portions of the inner protrusion, and each outer surface of the inner skirts and each inner surface of the outer skirts are surface-bonded in a state of being matched with each other, wherein a gap is formed between the outer surface of the inner protrusion and the inner surface of the outer protrusion to form a closed section.

The welding may be linearly performed along the end portion of the inner skirt and the inner surface of the outer skirt contacting the end portion of the inner skirt, and the outer surface of the inner skirt and the inner surface of the outer skirt may be partially welded in the longitudinal direction thereof.

The outer surface of the inner skirt and the inner surface of the outer skirt may be weld-bonded at regular intervals in the longitudinal direction of the inner skirt and the outer skirt.

The outer surface of the inner skirt and the inner surface of the outer skirt may be weld-bonded to the upper and lower portions at regular intervals in the longitudinal direction of the inner and outer skirts, and bonded such that the welding positions of the upper and lower portions are staggered from each other.

The outer surface of the inner skirt and the inner surface of the outer skirt may be weld-joined in the longitudinal direction of the inner skirt and the outer skirt, and may be joined such that a welding range of a central portion of the torsion beam is longer than other welding ranges of both sides of the central portion of the torsion beam.

The outer surface of the inner skirt and the inner surface of the outer skirt may be weld-bonded in the longitudinal direction of the inner skirt and the outer skirt, and may not be welded at the central portion of the torsion beam but only at both sides of the central portion of the torsion beam.

The gap may be formed by offsetting a cross section of the inner protrusion to a shape corresponding to a cross section of the outer protrusion.

The gap may be formed between the entire outer surface portion of the inner protrusion and the entire inner surface portion of the outer protrusion.

A front surface of the outer surface of the inner skirt may be in surface contact with an inner surface of the outer skirt.

A concave curvature whose curvature direction changes toward the inner side of the inner beam may be formed at a position where the outer surface of the inner protrusion and the outer surface of the inner skirt are connected.

An identical section portion formed by maintaining a closed section of the same shape may be formed at central portions of the outer and inner sills, and variable section portions formed by varying the shape of the closed section may be formed at both sides of the identical section portion.

The variable cross-section portion may include: a first variable portion configured such that one side of the first variable portion is connected to a side of the same section portion, and an upper end portion of the inner beam is gradually inclined downward to gradually increase a vertical height of the closed section; and a second variable portion configured such that one side of the second variable portion is connected to the other side of the first variable portion, an upper end portion of the outer beam and an upper end portion of the inner beam are formed in a horizontal sectional shape having a width of a predetermined length or more, and the other side of the second variable portion is connected to a side surface of the trailing arm.

The end portions of the outer beam and the inner beam may be formed in a shape surrounding a portion of the side surface of the trailing arm, the upper end portion of the outer beam may be coupled with the upper surface of the trailing arm, and the upper end portion of the inner beam is coupled with the bottom surface of the trailing arm.

A jig hole may be formed in the variable sectional portion adjacent to the same sectional portion of the upper end portion of the outer beam.

A receiving surface may be formed on an upper end portion of the inner beam facing the jig hole in a direction perpendicular to an axial direction of the jig hole.

Other features and advantages of the methods and apparatus of the present invention will be more particularly apparent from or elucidated with reference to the drawings described herein, and subsequently, described in conjunction with the accompanying drawings, which serve to explain certain principles of the invention.

Drawings

Fig. 1 is a view exemplarily illustrating the shape of a coupled torsion beam axle according to various exemplary embodiments of the present invention.

Fig. 2 is a view separately showing the shapes of an outer beam and an inner beam according to various exemplary embodiments of the present invention.

Fig. 3 is a view exemplarily showing a sectional shape in which an outer beam and an inner beam are coupled to each other according to various exemplary embodiments of the present invention.

Fig. 4, 5, 6, and 7 are views illustrating examples of different patterns of portions where an outer beam and an inner beam are coupled according to various exemplary embodiments of the present invention.

Fig. 8 is a view for describing a state in which the shape of a closed section formed between an outer beam and an inner beam is changed, according to various exemplary embodiments of the present invention.

It should be understood that the drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the invention disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes, will be determined in part by the particular application and environment of use contemplated.

In the drawings, like or equivalent elements of the invention are designated by reference numerals throughout the several views of the drawings.

Detailed Description

Reference will now be made in detail to various embodiments of the invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in conjunction with the exemplary embodiments, it will be understood that this description is not intended to limit the invention to those exemplary embodiments. On the other hand, the invention is intended to cover not only these exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

Exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Fig. 1 is a view exemplarily illustrating a coupled torsion beam axle according to various exemplary embodiments of the present invention.

Referring to fig. 1, a torsion beam 1 is formed in a "U" shaped cross section that opens downward such that both end portions of the torsion beam 1 are configured to be disposed in the left-right direction of a vehicle body, a pair of trailing arms 2 are coupled to both end portions of the torsion beam 1, respectively, and both end portions of the trailing arms 2 are configured to be disposed in the front-rear direction of the vehicle body.

Further, although not shown in fig. 1, a rear wheel is coupled to the outside of the rear end portion of the trailing arm 2, and a lower end portion of the shock absorber is coupled to the inside of the rear end portion of the trailing arm 2.

Meanwhile, the torsion beam 1 of the coupled torsion beam axle of the present invention is configured to include an outer beam 10 and an inner beam 20.

Fig. 2 is a view respectively showing shapes of an outer beam 10 and an inner beam 20 according to various exemplary embodiments of the present invention, and fig. 3 is a view exemplarily showing a sectional shape in which the outer beam 10 and the inner beam 20 according to various exemplary embodiments of the present invention are coupled to each other.

Referring to fig. 2 and 3, first, the outer beam 10 is formed in a sectional shape in which an outer protrusion 12 of a middle portion of an end portion thereof is protruded upward in a longitudinal direction of the outer beam, and the outer skirt 14 extends longitudinally in a vertical direction at both end portions of the outer protrusion 12.

For example, the outer protrusion 12 is formed in a cup shape in which an upper end portion thereof is horizontal and both horizontal end portions are inclined downward in an outward direction thereof, and in a sectional structure in which the outer skirt 14 is formed in a straight line in a downward direction at front and rear end portions of the outer protrusion 12.

Further, the inner beam 20 is formed in a sectional shape in which an inner protrusion 22 of a middle portion of an end portion thereof is inserted into the outer beam 10 to face the outer protrusion 12, and inner skirts 24 extend in a vertical direction at both end portions of the inner protrusion 22. Thus, the outer surface of the inner skirt 24 and the inner surface of the outer skirt 14 are surface-bonded in a mutually mated state.

For example, the inner protrusion 22 is also formed in a cup shape protruding upward in cross section, and is formed in a structure in which the inner skirt 24 is formed in a straight line in the downward direction at the front end portion and the rear end portion of the inner protrusion 22.

A gap g is formed between the outer surface of the inner protrusion 22 and the inner surface of the outer protrusion 12 to form a space of a closed section between the outer beam 10 and the inner beam 20.

That is, the outer and inner girders 10 and 20 are provided by press-forming a plate material, respectively, and the inner protrusion 22 of the inner girder 20 is coupled in such a manner as to be fitted in the outer protrusion 12 of the outer girder 10.

However, a gap g is formed along the outer surface of the inner protrusion 22 and the inner surface of the outer protrusion 12 to form a space of a closed section between the outer beam 10 and the inner beam 20. In addition, the outer surface of the inner skirt 24 is coupled to the inner surface of the outer skirt in a surface contact state, thereby increasing a coupling area between the outer girder 10 and the inner girder 20.

Therefore, by implementing the closed cross-sectional structure on the section of the beam where torsion occurs, it is possible to enhance the rigidity of the torsion beam 1 to ensure the same high roll rigidity as the multi-link mechanism, and further, by increasing the coupling area between the outer beam 10 and the inner beam 20, it is possible to ensure the durability of the torsion beam 1.

Further, since the structure that increases durability and rigidity is not due to a structure that increases weight such as increasing the torsion beam 1 or increasing the thickness of the torsion beam 1, lightweight design of the CTBA is also possible.

In addition, the inner and outer girders 20 and 10 may be coupled by linear weld coupling W1, or may be coupled together with linear weld coupling W1 by using a plug weld coupling W2 method.

Referring to fig. 3, the weld joint W1 is made linearly along the end portion of the inner skirt 24 and the inner surface of the outer skirt 14 that is in contact with the end portion of the inner skirt 24.

Further, the outer surface of the inner skirt 24 and the inner surface of the outer skirt 14 may be applied with a pattern in the longitudinal direction, and a local weld bond W2 may be additionally performed.

Since the outer and inner beams 10 and 20 are press-formed, welding can be performed in a state where surface matching between the outer skirt 14 and the inner skirt 24 cannot be properly performed due to press-forming tolerance, depending on manufacturing conditions.

In this case, in addition to the linear welding, the plug welding that is partially bonded is added to ensure the surface matching between the outer skirt 14 and the inner skirt 24, and therefore, the quality of the welded portion can be ensured, and since the vertical length of the outer skirt 14 and the inner skirt 24 is increased to form the welded surface, additional rigidity can be ensured.

Fig. 4, 5, 6, and 7 are views illustrating examples of different patterns of plug welds at portions where the outer and inner beams 10 and 20 are combined according to various exemplary embodiments of the present invention, and the presence, location, and length of the plug welds may be variously set according to weak points of target stiffness and durability.

Fig. 4 is a view for explaining a first example of plug welding, and the inner skirt portion 24 and the outer skirt portion 14 are welded and joined at equal intervals W2 in the longitudinal direction of the inner skirt portion 24 and the outer skirt portion 14.

This may be the basic plug welding method of the outer beam 10 and the inner beam 20.

Fig. 5 is a view for explaining a second example of plug welding, and the inner skirt 24 and the outer skirt 14 are weld-bonded W2 at equal intervals in the upper and lower portions in the longitudinal direction of the inner skirt 24 and the outer skirt 14, and may be bonded in such a manner that the welding positions of the upper portion and the lower portion are shifted from each other.

This is a type for increasing the rigidity of the torsion beam 1, when the lengths of the outer skirt and the inner skirt 24 in the vertical direction are increased and the contact area thereof is increased, by forming the form of the zigzag welding at the upper and lower positions of the outer skirt and the inner skirt 24, the surface contact between the outer skirt and the inner skirt 24 can be formed more reliably, and the rigidity of the torsion beam 1 can be further increased by increasing the amount of material to secure the contact area.

Fig. 6 is a diagram for explaining a third example of plug welding, and the inner skirt 24 and the outer skirt 14 are weld-joined W2 in the longitudinal direction of the inner skirt 24 and the outer skirt 14, and may be joined such that the welding range of the central portion is longer than the other welding ranges on both sides of the central portion of the torsion beam.

Since the torsion of the torsion beam 1 due to torsion becomes excessive when the wheel stroke is large, the present invention reinforces a portion where the durability may be weakened by configuring the center portion of the torsion beam 1 to have a large torsion resistance.

Fig. 7 is a view for explaining a fourth example of plug welding, and the inner skirt 24 and the outer skirt 14 are weld-bonded W2 in the longitudinal direction of the inner skirt 24 and the outer skirt 14, and it is possible to perform no welding at the central portion of the torsion beam and to perform the weld-bonding W2 only at both sides of the central portion of the torsion beam.

That is, the degree of deformation caused by the plug welding heat differs according to the thickness of the torsion beam 1. In the case of reducing the weight of the torsion beam 1 by molding the inner and outer beams 20 and 10 using a thin plate material, since welding is not performed at the central portion of the torsion beam 1, thermal deformation can be minimized.

Meanwhile, as shown in fig. 3, according to various exemplary embodiments of the present invention, the gap g may be formed by offsetting the cross section of the inner protrusion 22 into a shape corresponding to the cross section of the outer protrusion 12.

Here, the gap g is formed between the entire outer surface portion of the inner protrusion 22 and the entire inner surface portion of the outer protrusion 12, and this may be applied to the middle portions (the same cross section will be described later) of the outer and inner rails 10 and 20 based on the left-right direction of the vehicle body.

That is, in the case where the torsion beam 1 is twisted, since the deformation of the center portion is the largest, the roll rigidity can be improved by adjusting the offset amount of the gap g formed at the center portion of the torsion beam.

Further, a structure is formed in which the front surface of the outer surface of the inner skirt 24 is brought into face contact with the inner surface of the outer skirt.

That is, by securing the vertical length of the inner skirt 24 as long as possible while forming the vertical length of the outer skirt 14 to cover the length of the inner skirt 24 to increase the bonding area, when torsion of the torsion beam 1 occurs, a phenomenon of torsional stress concentration is prevented, thereby improving durability of the torsion beam 1.

Meanwhile, according to various exemplary embodiments of the present invention, a concave curved portion R whose curved direction changes toward the inner side of the inner beam 20 may be formed at a position where the outer surface of the inner protrusion 22 is connected with the outer surface of the inner skirt 24.

For example, an upper end portion of the bent portion R is connected to a lower end portion of the inner protrusion 22, a lower end portion of the bent portion R is connected to an upper end portion of the inner skirt 24, and an intermediate portion of the bent portion R is formed in a shape turned inside in toward the inside of the inner beam 20.

That is, in the case where the bent portion R is not formed at the portion where the inner protrusion 22 and the inner skirt 24 are connected, the gap g formed between the portion where the inner protrusion 22 and the inner skirt 24 are connected and the inner surface of the outer beam 10 is narrowed, and thus, not only is there a limitation in securing the rigidity of the corresponding portion, but also the coating performance is deteriorated.

Therefore, according to various exemplary embodiments of the present invention, since the bent portion R is formed at the position where the inner protrusion 22 and the inner skirt 24 are connected, the gap g between the bent portion R and the inner surface of the outer beam 10 is increased to additionally secure the rigidity of the torsion beam 1 and secure the paint fluidity, thereby improving the coating performance.

In an exemplary embodiment of the present invention, the curved portion R may be formed to have a predetermined curvature.

Meanwhile, fig. 8 is a view for describing a state in which the shape of a closed section formed between the outer and inner girders 10 and 20 is changed, according to various exemplary embodiments of the present invention.

Referring to fig. 8, the same section portion L1 formed by maintaining a closed section of the same shape is formed at the center portions of the outer and inner rails 10 and 20 formed in the left-right direction of the vehicle body, and variable section portions formed by changing the shape of the closed section are formed at both sides of the same section portion L1.

That is, when torsion occurs in the torsion beam 1, the central portion, which is most likely to be deformed, is formed to maintain the same sectional shape as the closed sectional structure, and the variable section of the closed sectional structure is formed to improve the bondability with the trailing arm 2 at both sides of the central portion of the torsion beam.

The variable section portion is a first variable portion L2 and a second variable portion L3, the first variable portion L2 is configured such that one side thereof is connected to a side of the same section portion L1, and the upper end portion of the inner beam 20 is gradually inclined downward to gradually increase the vertical height of the closed section.

The second variable portion L3 is configured such that one side thereof is connected to the other side of the first variable portion L2, the upper end portion of the outer beam 10 and the upper end portion of the inner beam 20 are formed in a horizontal sectional shape having a width of a predetermined length or more, and the other side is connected to the side surface of the trailing arm 2.

Further, in the case of the second variable portion L3, the end portions of the outer beam 10 and the inner beam 20 are formed in a shape surrounding a part of the side surface of the trailing arm 2, and the upper end portion of the outer beam 10 is joined with the upper surface of the trailing arm 2.

Further, the upper end portion of the inner beam 20 is joined to the bottom surface of the trailing arm 2.

That is, the same section portion L1 is the maximum torsion point of the torsion beam 1, and the torsional rigidity of the torsion beam 1 is ensured by keeping the shape and area of the closed section between the inner beam 20 and the outer beam 10 the same.

However, in the first variable portion L2, the lengths of the upper and lower portions of the closed sectional shape may be increased such that the end portions of the inner and outer beams 20 and 10 surround the side circumferences of the trailing arms 2, and also the front-rear direction widths thereof are increased. For this reason, in the first variable portion L2, the length of the lower end portion of the outer skirt 14 may be formed to extend downward while performing the upward molding of the upper end portion of the outer protrusion 12, and the length of the lower end portion of the inner skirt 24 may be formed to extend downward while performing the downward molding of the upper end portion of the inner protrusion 22.

Further, since the inner and outer sills 20 and 10 in the second variable portion L3 have a wider horizontal sectional shape of the upper end portion than the inner and outer sills 20 and 10 in the first variable portion L2, the area bonded to the upper and lower surfaces of the trailing arm 2 is widened, thereby improving the welding firmness with the trailing arm 2.

Further, according to various exemplary embodiments of the present invention, the jig hole 16 may be formed in the variable cross-sectional portion adjacent to the same cross-sectional portion L1 of the upper end portion of the outer beam 10, and the jig hole 16 may be formed at a position where the first variable portion L2 starts in the same cross-sectional portion L1.

Further, a receiving surface 26 may be formed on an upper end portion of the inner beam 20 facing the jig hole 16 in a direction perpendicular to the axial direction of the jig hole 16.

Therefore, not only the fixing during the welding but also the gap between the outer and inner beams 10 and 20 can be measured through the jig hole 16.

However, when torsion of the torsion beam 1 occurs, deformation is the largest in the same cross-sectional portion L1, and therefore, when the jig hole 16 is located in the same cross-sectional portion L1, a durability crack may occur in the jig hole 16. Therefore, by forming the jig hole 16 while avoiding the same cross-sectional portion L1, it is possible to measure the gap between the outer beam 10 and the inner beam 20 while preventing the torsion beam 1 from being broken.

Therefore, according to various exemplary embodiments of the present invention, by forming a wide closed section structure on a section of the torsion beam 1 where torsion occurs, it is possible to increase the rigidity of the CTBA to ensure the same high roll rigidity as the multi-link mechanism, and further, by increasing the coupling area between the outer beam 10 and the inner beam 20, it is possible to ensure the manufacturability and durability of the torsion beam 1.

Further, since the structure having increased durability and rigidity is not realized due to the structure having increased weight such as adding the torsion beam 1 or increasing the thickness of the torsion beam 1, lightweight design of the CTBA is also possible.

For convenience in explanation and accurate definition in the appended claims, the terms "above", "below", "inner", "outer", "upper", "lower", "upward", "downward", "front", "rear", "back", "inside", "outside", "inward", "outward", "inner", "outer", "forward" and "rearward" are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. It will be further understood that the term "connected," or derivatives thereof, refers to both direct and indirect connections.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. The foregoing description is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable others skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the following claims and their equivalents.