CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2020-0038812, filed Mar. 31, 2020, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a torsion beam of a coupled torsion beam axle that satisfies durability performance without increasing a weight of a component through structural improvement of the torsion beam.

Description of Related Art

A suspension of a vehicle is an apparatus that prevents damage to a vehicle body or cargo and improves riding comfort by connecting an axle and the vehicle body to prevent vibration or shock received from a road surface from being directly transmitted to the vehicle body when driving, and is classified into a front suspension and a rear suspension.

As a rear suspension for light and semi-medium-sized passenger cars, a coupled torsion beam axle (CTBA) that exhibits relatively high driving stability compared to low unit cost and mass is used.

When pitching occurs in the vehicle body while driving, the coupled torsion beam axle absorbs the pitching through a torsional elastic force of a member.

Furthermore, when the vehicle is turning driving, a displacement difference between the left and right wheels occurs according to a roll behavior of the vehicle, and a torsion bar, which is an intermediate member of the axle, is twisted, improving roll rigidity. As a result, the coupled torsion beam axle is configured to secure turning stability.

A high performance vehicle may secure fast responsiveness in terms of handling due to high roll rigidity characteristics, and in small and medium-sized high performance vehicles, a high rigidity coupled torsion beam axle is essential because a coupled torsion beam axle is applied to the rear wheel.

However, the high rigidity coupled torsion beam axle has a problem in that the durability/strength performance deteriorates as an input load increases, and has a side effect of increasing the weight of the components when the components are increased to increase the rigidity. Accordingly, there is a demand for a lightweight, high rigidity, coupled torsion beam axle structure which may satisfy durability performance without significantly increasing the weight of the components.

The information included in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and may 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.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing a torsion beam of a coupled torsion beam axle that satisfies durability performance without increasing a weight of a component 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 external beam having a first cross-section in which an external protrusion of a middle end portion of the external beam is formed to protrude toward upward in a longitudinal direction of the external beam, and external skirt portions are vertically extended along the longitudinal direction at both end portions of the external protrusion; and an internal beam having a second cross-section in which an internal protrusion of a middle end portion in the internal beam is inserted into the external beam to face the external protrusion of the external beam, and internal skirt portions are extended in a vertical direction at both end portions of the internal protrusion, and each external surface of the internal skirt portions and each internal surface of the external skirt portions are surface-bonded in a mutually matched state, wherein a gap is formed between an external surface of the internal protrusion and an internal surface of the external protrusion to form a closed cross-section.

A welding bonding may be linearly performed along an end portion of the internal skirt portion and the internal surface of the external skirt portion contacting with the end portion of the internal skirt portion, and the external surface of the internal skirt portion and the internal surface of the external skirt portion may be partially welding-bonded in a longitudinal direction thereof.

The external surface of the internal skirt portion and the internal surface of the external skirt portion may be welding-bonded at regular intervals in the longitudinal direction of the internal skirt portion and the external skirt portion.

The external surface of the internal skirt portion and the internal surface of the external skirt portion may be welding-bonded at regular intervals in upper and lower portions in the longitudinal direction of the internal skirt portion and the external skirt portion, and are bonded so that welded positions of the upper and lower portions are staggered with each other.

The external surface of the internal skirt portion and the internal surface of the external skirt portion may be welding-bonded in the longitudinal direction of the internal skirt portion and the external skirt portion, and may be bonded so that a welded range of a center portion of the torsion beam is longer than other welded ranges of both sides of the center portion of the torsion beam.

The external surface of the internal skirt portion and the internal surface of the external skirt portion may be welding-bonded in the longitudinal direction of the internal skirt portion and the external skirt portion, and may not be welded at the center portion of the torsion beam, but be welded only at both sides of the center portion of the torsion beam.

The gap may be formed by offsetting a cross section of the internal protrusion into a shape corresponding to a cross section of the external protrusion.

The gap may be formed between the entire external surface section of the internal protrusion and the entire internal surface section of the external protrusion.

A front surface of the external surface of the internal skirt portion may be in surface-contact with the internal surface of the external skirt portion.

A concave inflection portion in which a direction of bending thereof changes toward an internal side of the internal beam may be formed at a point where the external surface of the internal protrusion and the external surface of the internal skirt portion are connected.

The same cross-sectional section formed by maintaining the same shape of the closed cross-section may be formed at the center portion of the external beam and the internal beam, and variable cross-sectional sections formed by varying the shape of the closed cross-section may be formed at both sides of the same cross-sectional section.

The variable cross-sectional sections may include: a first variable section configured so that one side thereof is connected to a side portion of the same cross-sectional section, and the upper end portion of the internal beam is gradually inclined downward to gradually increase a vertical height of the closed cross-section, and a second variable section configured so that one side thereof is connected to the other side of the first variable section, the upper end portion of the external beam and the upper end portion of the internal beam are formed in a horizontal cross-sectional shape having a width of a predetermined length or more, and the other side thereof is connected to the side surfaces of the trailing arms.

The end portions of the external beam and the internal beam may be formed in a shape surrounding a portion of the side surfaces of the trailing arms, an upper end portion of the end portion of the external beam may be bonded to the upper surfaces of the trailing arms, and an upper end portion of the end portion of the internal beam may be bonded to bottom surfaces of the trailing arms.

A jig hole may be formed in a variable cross-sectional section adjacent to the same cross-sectional section of the upper end portion of the external beam.

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

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

