CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This PCT Patent Application claims the benefit of U.S. Provisional Patent Application Serial Number 63/107,058 filed on October 29, 2020 entitled “Twist Axle Assembly,” the entire disclosure of the application being considered part of the disclosure of this application and hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The present invention relates a twist axle assembly and a method of assembling same. More particularly, the present invention relates to a twist axle assembly that includes a flanged portion and method of assembling the flanged portion from a material transition zone.

2. Related Art

[0002] This section provides background information related to the present disclosure which is not necessarily prior art.

[0003] A twist beam rear axle suspension assembly, also known as a torsion beam axle, is a type of automobile suspension system including a pair of trailing arms, each of which is coupled with a wheel of a vehicle, and a twist beam which extends transversely between the trailing arms. During operation of the vehicle, the twist beam deforms in a twisting movement when one of the wheels moves relative to another, such as during vehicle body roll or when one of the wheels encounters, for example, a pothole or an obstacle in a road. The twisting movement of the twist beam absorbs this movement to make the ride more comfortable for occupants in the vehicle body.

[0004] In general, it is desirable to provide the twist beam with a pair of regions with a relatively increased stiffness at the ends of the twist beam and a relatively reduced stiffness in the longitudinal middle region of the twist beam. One approach to providing the twist beam with a middle region of reduced stiffness and end regions of increased stiffness is to form the twist beam of a tube and crush or otherwise deform the tube into a U or V shape in the middle region. However, this process is difficult to uniformly implement and may require one or more post-shaping heat treating operations that increase the cost of the resulting twist beam. Another approach is to stamp the twist beam to its shape and then to weld brackets to the longitudinal ends. Under this approach, the welded brackets provide the increased stiffness in the end portions.

[0005] Accordingly, there is a continuing desire to further develop twist beam construction and operation such that regions of the twist beam have desirable material properties, such as, reducing or eliminating fatigue to welds and trim edges.

SUMMARY OF THE INVENTION

[0006] The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent embodiments do not depart from the spirit and scope of the invention as set forth in the appended claims. This section provides a general summary of the disclosure and is not to be interpreted as a complete and comprehensive listing of all of the objects, aspects, features and advantages associated with the present disclosure. [0007] According to one aspect of the disclosure, a twist axle assembly for a vehicle is provided. The twist axle assembly comprises a twist beam extending along a lateral direction and having a top surface, a bottom surface, a rear surface, and a front surface. The twist beam includes a pair of end portions laterally spaced by a pair of transition zones and a middle portion located between the transition zones. An opening is formed in the middle portion and the transition zones that is outlined by a rim having opposing edges and each of the opposing edges includes a flanged portion.

[0008] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The drawings described herein are for illustrative purposes only of selected embodiments and are not intended to limit the scope of the present disclosure. The inventive concepts associated with the present disclosure will be more readily understood by reference to the following description in combination with the accompanying drawings wherein:

[0010] Figure 1 A is a top perspective view of a first exemplary embodiment of a twist axle assembly including a twist beam;

[0011] Figure IB is a top perspective view of the twist beam from Figure 1 A detached from a pair of trailing arms;

[0012] Figure 2A a bottom perspective view of the first exemplary embodiment of a twist axle assembly;

[0013] Figure 2B is a bottom perspective view of the twist beam from Figure 2A detached from the pair of trailing arms; [0014] Figure 3A is a front view of the first exemplary embodiment of a twist axle assembly;

[0015] Figure 3B is a front view of the twist beam from Figure 3A detached from the pair of trailing arms;

[0016] Figure 4A is a rear view of the first exemplary embodiment of a twist axle assembly;

[0017] Figure 4B is a rear view of the twist beam from Figure 4A detached from the pair of trailing arms;

[0018] Figure 5 A is a top view of the first exemplary embodiment of a twist axle assembly;

[0019] Figure 5B is a top view of the twist beam from Figure 5 A detached from the pair of trailing arms;

[0020] Figure 6A is a bottom view of the first exemplary embodiment of a twist axle assembly;

[0021] Figure 6B is a bottom view of the twist beam from Figure 6A detached from the pair of trailing arms;

[0022] Figure 7A is a left side view of the first exemplary embodiment of a twist axle assembly;

[0023] Figure 7B is a left side view of the twist beam from Figure 7A detached from the pair of trailing arms;

[0024] Figure 8A is a right side view of the first exemplary embodiment of a twist axle assembly;

[0025] Figure 8B is a right side view of the twist beam from Figure 8A detached from the pair of trailing arms; [0026] Figure 9A is a cross-section taken along a middle portion of the first exemplary embodiment of a twist axle assembly;

[0027] Figure 9B is a cross-section taken along a transition zone of the first exemplary embodiment of a twist axle assembly;

[0028] Figure 10 is a cross-section taken along a transition zone of a second exemplary embodiment of a twist axle assembly;

[0029] Figure 11 is a cross-section taken along a transition zone of a third exemplary embodiment of a twist axle assembly; and

[0030] Figure 12 is a flow chart of a method of forming a twist axle assembly in accordance with each embodiment.

DESCRIPTION OF THE ENABLING EMBODIMENT

[0031] Example embodiments will now be described more fully with reference to the accompanying drawings. In general, the subject embodiments are directed to a twist axle assembly that includes a flanged portion and a method of assembling the flanged portion from a material transition zone. However, the example embodiments are only provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0032] Referring to the Figures, wherein like numerals indicate corresponding parts throughout the views, a first exemplary embodiment of an improved twist axle assembly 20 for a vehicle suspension system is generally shown in Figures 1 A through 9B. With reference to Figures 1 A through 2B, the twist axle assembly 20 includes a pair of trailing arms 22 and a twist beam 24 (also known as a cross-member) that extends in a lateral direction (which, in use, corresponds with a lateral direction of a vehicle) between the trailing arms 22. The trailing arms 22 are configured for attachment with opposing wheels of the vehicle, and in use, the trailing arms 22 pivot relative to one another in response to the vehicle rolling while cornering at speed or in response to the wheels encountering an object, such as a pot hole. The twist beam 24 resists the relative rotation of the trailing arms 22 to reduce roll and generally improve the performance of the vehicle’s dynamics.

[0033] The twist beam 24 extends in a first direction between opposite ends and includes a pair of opposing end portions 26 that are spaced by a middle portion 28 and a pair of transition zones 29. The pair of opposing transition zones 29 (Figure IB) are located on opposite sides of the middle portion 28 spacing the middle portion 28 from the oppositely located end portions 26. The exemplary twist beam 24 is generally symmetrical in shape about a lateral midpoint MP of the twist beam 24. The end portions 26 of the twist beam 24 are connected with the trailing arms 22 for allowing the trailing arms 22 to rotate relative to one another during operation of the vehicle. The trailing arms 22 could have any suitable shapes or configurations. Both the twist beam 24 and the trailing arms 22 are preferably made of metal (such as, for example, steel, steel alloy, aluminum, aluminum alloys, magnesium, magnesium alloys, etc.). The end portions 26, the middle portion 28, and the transition zones 29 of the twist beam 24 are defined by at least one sidewall 30 that may be formed of a single piece of shaped material that includes a pair of opposing edges 31, 33 that are brought into close proximity when the twist beam 24 is formed. The sidewall 30 includes mating surface 32, such as U-shaped recesses, formed therein that overlay similar mating surfaces on the trailing arms 22 for establishing a gloved connection with the trailing arms 22. Specifically, the trailing arms 22 are slid into the mating surface

32 (e.g., U-shaped recesses) on the end portions 26, and then these two components are connected together (for example, through MIG welding, TIG welding, laser welding, etc.).p [0034] As best illustrated in Figures 3A and 4A, the twist beam 24 may include a variable width along its length to vary a torsional stiffness of the twist beam 24 between the front surface 34 (Figures 3A and 3B) and the rear surface 36 (Figures 4A and 4B). For example, a similar shape is disclosed in PCT Published Patent Application WO 2016- 061078 Al published April 21, 2016 and PCT Published Patent Application WO 2016- 133753 Al published August 25, 2016, which are both incorporated herein in entirety. Specifically, at least part of the middle portion 28 around the midpoint MP of the twist beam 24, has a first width Wi, and a portion of each of the end portions 26 has a second width W2 that is greater than the first width Wi. The twist beam 24 transitions gradually from the lesser first width Wi of the middle portion 28 to the greater second widths W2 of the end portions 26 for gradually increasing the torsional stiffness of the twist beam 24 from the middle portion 28 to the end portions 26. The twist beam 24 may further include a similar shape between the top surface 38 (Figures 5 A and 5B) and the bottom surface 40 (Figures 6A and 6B). This shape is advantageous because, during use, the majority of the twisting of the twist beam 24 occurs in the middle portion 28 with the lower torsional stiffness, thereby improving the durability of the weld joints between the twist beam 24 and the trailing arms 22 by protecting the weld joints from damage that could occur from twisting in the end portions 26.

[0035] As shown best in the left-side view (Figure 7B) and the right-side view (Figure 8B), the end portions 26 of the twist beam 24 have a closed (or nearly closed) geometrical profile, and the middle portion 28 and transition zones 29 have an open, and uncrushed, geometrical profile (Figures 2A and 2B). The end portions 26 may have generally trapezoidal cross-section with rounded comers. More specifically, the sidewall 30 defines the front surface 34, the rear surface 36, the top surface 38, and the bottom surface 40. In one example arrangement, the bottom surface 40 of the middle portion 28 and transition zones 29 define the open geometrical configuration. For example, the sidewall 30 is rolled with the opposing edges 31, 33 located on the bottom surface 40 and outlining a rim 44 that defines an opening 46 (Figure 9A). At least one flanged portion 42 extends from the bottom surface 40 to the opposing edges 31, 33. The cross-section of the midpoint MP through regions of the transition zone 29 may thus be generally U-shaped (Figures 7B, 8B, 9A, and 9B).

[0036] As best illustrated in Figures 6 A and 6B, the rim 44 includes a straight section 52 located on the middle portion 28 wherein the opposing edges 31, 33 are parallel and opposing in the lateral direction. The rim 44 further includes widened sections 54 on either side of the straight section 52 wherein the opposing edges 31, 33 diverge from the straight section 52 in the front-rear direction and re-converge in the front-rear direction as the rim 44 approaches the end portions 26 and terminate at opposite rim ends 56. The rim ends 56 may include a rounded profile wherein the opposing edges 31, 33 re-converge into close proximity and run parallel in the lateral direction to the terminal ends of end portions 26. A small space 58 (Figure 9B) may be located between the opposing edges 31, 33 in the end portions 26. Alternatively, the opposing edges 31, 33 may be connected at end portions 26. The twist beam 24 may further be provided with holes 60, or openings, that are spaced from one another in the lateral direction to further reduce the torsional stiffness of the middle portion 28 in comparison to the end portions 26 and thereby further protect the weld joints between the twist beam 24 and the trailing arms 22. The openings 60 may be located on the top surface 38. [0037] Figure 7A is a right-side view and Figure 7B is a left-side view of the trailing arms 22. Each trailing arm 22 includes a body attachment segment 62 for connection to a body of an automobile and a wheel attachment segment 64 for connection to a spindle or hub of an automobile. As best illustrated in Figures 7B and 8B, it should be appreciated in view of a vertical midline VM that the right end of the twist beam 24 (Figure 7B) that connects to the right trailing arm 22 is slightly angled from the VM and the left end of the twist beam 24 (Figure 8B) that connects to the left trailing arm 22 is slightly angled from the VM equally or oppositely to the right end. With continued reference to Figures 7B and 8B, the flanged portion 42 extends from opposing sides of the rim 44 in the transition zones 29 and may also be at least partially located on the middle portion 28. More particularly, the flanged portion 42 on the opposing edge 31 near the front surface 34 extends from the opening 46 away from the bottom surface 40 towards the front surface 34 and the flanged portion 42 on the opposing edge 33 near the rear surface 36 extends symmetrically from the bottom surface 40 towards the rear surface 26.

[0038] Additional details of the flanged portion 42 according to a first embodiment are best illustrated in the isometric cross-section of the twist beam 24 presented in Figures 9 A and 9B. The flanged portion 42 extends from rounded comers between the side surfaces (front surface 34 and rear surface 36) and the bottom surface 40. The rounded comers are defined by a first radius R1 and the flanged portion 42 extends from the rounded comers to a rounded portion 68 defining a second radius R2. The first radius R1 and the second radius R2 are oppositely located so that the rounded comers and the rounded portion 68 together form a general S-shape. The first radius R1 may be smaller, equal, or larger than the second radius R2. Similarly, the radians or degrees of the rounded comers may be less, equal, or more than the radians or degrees of the rounded portion 68. The flanged portion 42 may further include a straight portion 70 which extends from the rounded portion 68 to the opposing edges 31, 33 and forms part of the general S-shape. In some embodiments, the opposing edges 31, 33 are orientated parallel to the bottom surface 40 on the straight section 52 and/or widening sections 54 and form a twist 72 portion on the flanged portion 42 that bends until the opposing edges 31, 33 become perpendicular to the bottom surface 40 on the rim ends 56.

[0039] As illustrated in Figure 9 A, the radius Rl, the radius R2, the radians of the rounded comer, and/or the radians of the rounded portion 68 may increase or decrease in the direction of end portions 26 (Figure 9B) within the transition zone 29 and/or portions of the middle portion 28. Moreover, the straight portion 70 (extending from the bottom surface 40) of the flanged portion 42 may become lager, extending further from the bottom surface 40, within the transition zone 29. As best illustrated in Figure 4B, the flanged portion 42 bows outwardly from the middle portion 28 and becomes larger to an apex 74 (the furthest portion of the flanged portion 42 from the bottom surface 40) as it approaches the end portions 26 within the transition zone 29. After the apex 74, the flanged portion 42 may then bow back inwardly at a greater rate than it bows outwardly.

[0040] With reference now to Figure 10, a second embodiment of the twist beam 124 is illustrated. The second embodiment may include all the features, shapes, and constructions of the other embodiments that do not directly conflict with the modified structure. The twist beam 124 of the second embodiment includes a flanged portion 142 that includes a rounded portion 168 defining a radius R3 that merges with and at least partially carries over to an adjacent rounded comer 144 around an opening 146 defined by a pair of edges 131(opposing edge 33 not shown). The flanged portion 142 may further include a straight portion 170 that extends further into the opening 146 from the rounded portion 168. The straight portion 170 tapers towards the bottom side 40 as it extends towards an end portion 126 and may be bowed in similar regions as that described in reference to the first embodiment. The flanged portion 142 may also extend from at least part of a middle portion (not shown) of the twist beam 124.

[0041] With reference now to Figure 11, a third embodiment of the twist beam 124 is illustrated. The third embodiment may include all the features, shapes, and constructions of the other embodiments that do not directly conflict with the modified structure. The twist beam 224 of the third embodiment includes a flanged portion 242 that includes a rounded portion 268 extending radially outwardly from one of the surfaces, for example, either a front surface 234 or a rear surface (not shown) to increase the width of an opening 246. The rounded portion 268 defines a radius R4 and it leads to a straight portion 270 that twist until the opposing edges 231 (opposing edge 33 not shown) face each other. The edges 231 outline a rim 244 which defines the opening 246 and further defines rounded comers 244 that merge near end portions (not shown).

[0042] The torsional stiffness of the twist beam 24, 124, 224 of the various embodiments described herein may therefore transition gradually from a minimum torsional stiffness at an approximate midpoint MP to a maximum torsional stiffness at the end portions 26. In some embodiments, twist beam 24, 124, 224 may be configured such that the torsional stiffness changes at a constant rate from the minimum torsional stiffness to the maximum torsional stiffness. The flange portions 42, 142, 242 and transition zones 29, 129, 229 are configured to reinforce the cross-section and improve the fatigue performance on the edges 31, 33, 131, 231 which may be trimmed to shape during the formation of the twist beam 24, 124, 224. The open section middle portion 28 is configured to allow the twist beam 24, 124, 224 to be torsion-flexible in case of twist events while keeping the bending stiffness of the twist beam 24, 124, 224 on a high level to maintain wheel toe and camber stiffness. The end portions 26 of the twist beam 24, 124, 224 are configured as a closed section beam allowing maximum rigidity in order to protect the welded joint of the mating surface 32 to the trailing arms 22 from fatigue damage. The various rounded portions defined by radii Rl, R2, R3, and R4 reinforce the open cross section of the middle portion 28, 128, 228 and transition zones 29, 129, 229. The regions of the flange portions 42, 142, 242, such as straight sections 70, 170, 270 extending from the rounded portions defined by radii Rl, R2, R3, and R4 space the radii and the opposing edges 31, 33, 131, 231 (“trim edges”) in order to protect the trim edge from fatigue damage. The flange portions 42, 142, 242 including radii Rl, R2, R3, and R4 may gradually disappear when continuing towards to the closed or semi-closed end portions 26. The openings 46, 146, 246 may further provide material savings costs and a reduction in weight.

[0043] Another aspect of the present invention provides a method 300 of making a twist axle assembly for use in a vehicle suspension system. At 302, the method 300 includes providing a pair of trailing arms. At 304, the method 300 continues with stamping a workpiece (such as a generally planar blank) into a twist beam with a pair of end portions, a middle portion, and at least one transition portion having the features and shapes described herein. At 306, the step 304 may further include forming a flanged portion having characteristics having the features and shapes described herein. At 308, the step 304 may further include forming the twist beam into a generally hour-glass shaped with the middle portion having a first width which is generally smaller than a width of the end portions. At 310, the step 304 may further include forming the twist beam in a configuration in which a torsional stiffness of the twist beam gradually increases from the middle portion to the end portions. At 312, the method proceeds with forming an opening between opposing edges that widens from a middle portion and converges near end portions At 314, the method proceeds with attaching the end portions of the twist beam with the trailing arms, for example, via MIG welding, TIG welding, or laser welding. [0044] It should be appreciated that the foregoing description of the embodiments has been provided for purposes of illustration. In other words, the subject disclosure it is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varies in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of disclosure.