Vehicle torsion beam

Abstract

To provide a torsion beam that ensures appropriate torsional rigidity and bending strength while allowing easy cross-sectional design and formation of each portion.SOLUTION: In a torsion beam having a closed cross-sectional structure that connects left and right trailing arms of a vehicle body, the closed cross section is formed of a circular and / or elliptical cross section, and a beam central portion located at a center in a vehicle body left-right direction is configured such that a circumferential length of the closed cross section gradually increases toward end portions.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a torsion beam of a torsion beam suspension for a vehicle. [Background technology]

[0002] Patent Document 1 describes a torsion beam suspension, which is one type of vehicle suspension. This suspension includes trailing arms on the left and right sides of the vehicle body that support the wheels, and a torsion beam that connects the two trailing arms. The trailing arms have a joint at their base end that is rotatably connected to the vehicle body, and a wheel support unit attached to the other end. The end of the torsion beam is connected to the trailing arm.

[0003] Torsion beams must have appropriate torsional rigidity from the perspective of controlling the vehicle's posture when it rolls. On the other hand, because the ends of the torsion beam are connected to the trailing arm, it is necessary to ensure the connection strength while also ensuring fatigue stress. For this reason, torsion beams with a cylindrical, closed cross-section structure are generally used.

[0004] Recently, beams have been made more flexible by giving the central cross-sectional shape an approximately V-shape or an approximately U-shape. Specifically, the cross-sectional shape is changed so that the distance between the upper and lower walls in the cross section gradually increases from the central part to both ends of the beam, that is, the cross-sectional area and perimeter gradually increase, thereby achieving both torsional rigidity and bending strength of the beam.

[0005] In particular, Patent Document 1 discloses a torsion beam structure in which, in order to achieve both further optimization of torsional rigidity and ensuring bending strength, increasing circumferential portions are provided at both ends of the torsion beam, with the circumferential length increasing toward the beam ends, and the cross section is gradually changed so that the width of the increasing circumferential portions in the fore-and-aft direction of the vehicle body gradually increases toward the beam ends, and the rate of increase also increases toward the ends. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6893637 Summary of the Invention [Problem to be solved by the invention]

[0007] However, designing a roughly V-shaped or U-shaped cross-sectional shape for each longitudinal portion of a torsion beam that can optimize the torsional rigidity and ensure bending strength requires complex cross-sectional design and analytical verification for each design. Even if an optimal cross-sectional shape could be designed for each portion, it would be difficult to precisely realize the optimal cross-sectional shape for each portion by plastic processing such as press forming from a steel pipe, and there are problems such as the increased cost and man-hours required for each forming mold.

[0008] Therefore, an object of the present invention is to provide a torsion beam that ensures appropriate torsional rigidity and bending strength while allowing easy setting and formation of the cross-sections of each portion. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the present invention provides a torsion beam with a closed cross-section structure that connects the trailing arms on the left and right sides of the vehicle body, in which the closed cross-section is composed of a circular and / or elliptical cross-section, and the perimeter of the closed cross-section gradually increases from the central part of the beam located in the center of the vehicle body in the left-right direction toward the ends. [Effects of the Invention]

[0010] According to the present invention, by setting the optimum perimeter of the circle or ellipse at each portion of the torsion beam, it becomes easy to set and manufacture a torsion beam that has both appropriate torsional rigidity and bending strength. [Brief explanation of the drawings]

[0011] [Figure 1]1 is a perspective view of a torsion beam suspension using a torsion beam according to a first embodiment of the present invention. FIG. [Figure 2] 1A and 1B are a front view and a top view of a torsion beam according to a first embodiment of the present invention. [Figure 3] 1 is a comparison table illustrating cross-section setting methods according to the present invention and the prior art. [Figure 4] 10A and 10B are a front view and a top view of a torsion beam according to a second embodiment of the present invention. [Figure 5] 10A and 10B are a front view and a top view of a torsion beam according to a third embodiment of the present invention. [Figure 6] 10A and 10B are a front view and a top view of a torsion beam according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] A preferred embodiment of the present invention will be described below with reference to Figures 1 to 6. In this embodiment, the traveling direction of the vehicle is represented as Fr, the horizontal direction perpendicular to the traveling direction is represented as lateral, particularly the right side, as RH, and the vertical direction perpendicular to the traveling direction is represented as upward, as H.

[0013] (First embodiment) FIG. 1 is a perspective view showing a torsion beam suspension 1 using a torsion beam 5 according to a first embodiment of the present invention. Trailing arms 2 are firmly connected to both ends of the torsion beam 5 by welding or other means. Attached to one end (base end) of each trailing arm 2 is a joint 3, which is a connecting part for rotatably connecting the trailing arm 2 to a vehicle and is made up of a pivot and a rubber bushing. Attached to the other end of each trailing arm 2 is a wheel support 4 for rotatably supporting a wheel.

[0014] 2 shows a torsion beam 5 according to a first embodiment of the present invention, with (b) a front view as seen from the vehicle longitudinal direction and (a) a top view as seen from above the vehicle. The central portion of the torsion beam 5 is indicated as W0. In the top view (a), the torsion beam 5 extends linearly in the vehicle width direction (RH) and curves upward in the vehicle height direction (H) so that its axis 6 reaches its highest point at the central portion W0. The vehicle width direction is sometimes referred to as the vehicle left-right direction.

[0015] The cross-sectional shapes of each portion are also shown at the bottom of the front view (b) of Figure 2. From the central portion 0 toward the ends in the vehicle width direction, the W1 portion, W2 portion, and W3 portion are located in that order. The cross section at the central portion W0 is a circular cross section with a diameter (φ) A, the W1 portion is a circular cross section with a diameter B, the W2 portion is a circular cross section with a diameter C, and the W3 portion (connection portion) is a circular cross section with a diameter D. In other words, the torsion beam 5 has a closed cross-sectional structure with a circular closed cross section, and while the same circular cross-sectional shape is maintained from W0 to W3, the diameter, i.e., the perimeter, gradually increases. A complex, approximately V-shaped or approximately U-shaped cross section, as in prior art, is not used.

[0016] Here, the ease of cross-section setting and manufacturing of the present invention will be explained using Figure 3. Figure 3 is a comparison table explaining the cross-section setting methods of the present invention and the prior art, with the left column showing parameters (length, angle, etc.) that must be observed when setting a cross-section in the prior art, and the right column showing parameters that must be observed when setting a cross-section in the present invention.

[0017] For example, the cross section at W0 in the prior art (left column) is a roughly V-shaped cross section that opens downward and is formed from a closed cross-section member. The cross-sectional shape indicates parameters (●) that indicate the length and curvature of the straight and curved lines that make up the wall surface. In other words, nine parameters must be set to define the cross section at W0. The number of possible combinations is infinite, and changing one parameter affects the shape of the entire cross section, i.e., the cross-sectional properties (section modulus). Therefore, setting the parameters requires a huge amount of work and repeated characteristic verification. Furthermore, since the cross section is gradually changed at each of the sections from W0 to W3, the cross-sectional configuration parameters for each section must also be set.

[0018] Therefore, setting the cross-sectional configuration parameters of the entire torsion beam according to the prior art requires a huge number of provisional settings and repeated analysis to verify the characteristics, which requires a huge amount of work. Furthermore, even if the parameters for each cross section can be set, accurately forming the set cross section of each part through plastic processing requires a huge number of processing trials and modifications to the processing method and equipment.

[0019] In contrast, in the cross-section setting of the present invention shown in the right column, the parameter (▲) that needs to be determined is only the perimeter (= diameter) if the cross section is circular from W0 to W3. Even for an elliptical cross section, only two parameters, the major axis and the minor axis, are required. Note that in the present invention, a circular cross section is not limited to a strict perfect circle, and as long as it achieves the desired cross-sectional characteristic values, a slight diameter error (irregularity) due to the indexing angle can be tolerated. In other words, it is sufficient if the cross section is approximately circular within a certain diameter error range. Similarly, it is sufficient for an elliptical cross section to be approximately elliptical.

[0020] As described above, by simply setting one or two parameters for each cross section, it is now possible to easily design and form a torsion beam in which the closed cross section is composed of a circular and / or elliptical cross section and the perimeter of the closed cross section gradually increases from the center of the beam to the ends. Furthermore, a cylindrical body with such a gradually changing circular and / or elliptical cross section can be formed using the existing UO method, in which a plate is molded onto a mandrel. Alternatively, a hydroforming method can be applied, in which hydraulic pressure is applied inside a pipe to mold it onto an outer mold, resulting in a three-dimensional cylindrical body. Both methods also allow for the creation of a torsion beam with a gradually changing thickness in the axial direction using materials with different thicknesses (such as tailored blanks). Furthermore, using a circular or elliptical cross section instead of an approximately V- or U-shaped cross section can result in a relatively lighter body and reduced design and manufacturing costs.

[0021] (Second embodiment) 4A and 4B are a front view (b) of a torsion beam 7 according to a second embodiment of the present invention as seen from the longitudinal direction of the vehicle, and a top view (a) of the torsion beam 7 as seen from above the vehicle. Unlike the first embodiment, the central portion W0 of the torsion beam 7 is not displaced in the vehicle height direction (H). In other words, the torsion beam 7 is generally straight, and its axis 8 is linear. In this way, if there is no particular need to curve the axis of the torsion beam upward and / or in the longitudinal direction, and only the characteristic setting by the cross-sectional transition is required, the axis of the torsion beam may be linear.

[0022] The cases where it is necessary to curve the axis of the torsion beam upward and / or in the front-to-rear direction include when it is desired to adjust the overall bending deformation characteristics by curving the torsion beam, when it is desired to avoid interference with surrounding structures or parts, etc. According to the present invention, since the torsion beam is configured with a circular or elliptical cross section, it is easier to set and shape the characteristics when curvature is added compared to a cross-sectional shape that is approximately V-shaped or approximately U-shaped.

[0023] (Third embodiment) FIG. 5 shows a torsion beam 9 according to a third embodiment of the present invention, with (b) a front view as seen from the longitudinal direction of the vehicle and (a) a top view as seen from above the vehicle. The central portion W0 of the torsion beam 9 is displaced toward the front (Fr) of the vehicle in addition to being displaced in the vehicle height direction (H) as in the first embodiment. In other words, the torsion beam 9 is an entirely curved tube, and its axis 10 forms a curve that is convex in the vehicle height direction (H) and the vehicle front (Fr). According to the present invention, the torsion beam 9 can be formed and arranged (mounted on the vehicle) in three dimensions as described above.

[0024] (Fourth embodiment) FIG. 6 shows a torsion beam 11 according to a fourth embodiment of the present invention, with (b) a front view as seen from the longitudinal direction of the vehicle and (a) a top view as seen from above the vehicle. The torsion beam 11 has a linear axis 12, as in the second embodiment, but the cross section gradually changes from a circle to an ellipse between W2 and W3. The elliptical cross section at W3 has a major axis D1 and a minor axis D2. The major axis D1 allows for a longer joint area with the trailing arm 2, contributing to improved joint strength. Furthermore, the elliptical cross section can create anisotropy in deformation, improving the flexibility in designing the deformation characteristics of the entire torsion beam.

[0025] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and modifications that do not deviate from the spirit of the present invention are also included in the present invention. [Explanation of symbols]

[0026] 1 Torsion beam suspension 2 Trailing Arm 3 Joint 4 Wheel support part 5, 7, 9, 11 Torsion beam 6, 8, 10, 12 axes

Claims

1. A torsion beam with a closed cross-section structure that connects the left and right trailing arms of a vehicle body, the closed cross section comprises a circular and / or elliptical cross section; A torsion beam for a vehicle, characterized in that the circumferential length of the closed cross section gradually increases from a central portion of the beam located in the center of the vehicle body in the left-right direction toward the ends.

2. In claim 1, A torsion beam for a vehicle, wherein an axis passing through the center of the closed cross section is curved in the longitudinal direction of the vehicle and / or upward of the vehicle.

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