High-toughness weather-resistant torsion rod for automobile seat and safety belt

Abstract

The utility model discloses a kind of high toughness weatherable torsion bar for car seat and safety belt, it is integrally-formed rod structure, it includes first engagement portion, first shaft section, second engagement portion, second shaft section and third engagement portion in sequence along axial direction.The first shaft section is equipped with the first fillet transition structure between second engagement portion, and second engagement portion and second shaft section between and second shaft section and third engagement portion between are equipped with the second fillet transition structure.Outside diameter of first engagement portion is equal to first shaft section outer diameter, second engagement portion outer diameter is equal to third engagement portion outer diameter and greater than second shaft section outer diameter, and second shaft section outer diameter is greater than first shaft section outer diameter.The utility model is matched with specific fillet transition by optimizing stepped shaft diameter design, effectively improves stress distribution, significantly improves anti-fatigue performance and reliability, improves weathering toughness performance.

Description

Technical Field

[0001] This utility model belongs to the field of torsion bar technology, specifically relating to a high-strength, tough, and weather-resistant torsion bar for use in car seats and seat belts. Background Technology

[0002] Car seats and seat belts typically feature adjustment mechanisms to accommodate different seating positions. Torsion bars, as a key torque transmission component, are widely used in these mechanisms. Their working principle involves storing or releasing energy through the elastic torsion of the torsion bar, thereby adjusting and locking the backrest angle.

[0003] Existing torsion bars typically employ a multi-component assembly structure, where components such as the meshing sleeve and shaft segment are machined separately and then joined together through welding or press fitting. This modular structure has several inherent drawbacks: First, the connection points (such as welds or press-fit surfaces) are prone to stress concentration under repeated torsional loads, leading to decreased fatigue strength and a risk of premature fracture. Second, the assembly of multiple components inevitably introduces cumulative errors, affecting the overall precision and smoothness of the transmission system. Third, the manufacturing process is relatively complex and costly.

[0004] Therefore, based on some of the situations in the prior art described above, this application has made further designs and improvements. Utility Model Content

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution.

[0006] A high-strength, weather-resistant torsion bar for automotive seats and seat belts is disclosed. The torsion bar is a one-piece molded rod structure, which fundamentally eliminates weld seams or mating interfaces caused by multi-component assembly, significantly improving the overall structural strength and consistency of the product. The torsion bar includes, along its axial direction, a first engaging portion, a first shaft segment, a second engaging portion, a second shaft segment, and a third engaging portion. The first and third engaging portions are spline or gear structures for transmitting torque. A first rounded corner transition structure is provided between the first shaft segment and the second engaging portion. Second rounded corner transition structures are provided between the second engaging portion and the second shaft segment, and between the second shaft segment and the third engaging portion. The specialized design of the first and second rounded corner transition structures smoothly smooths the cross-sectional changes at the connection points between different shaft segments and engaging portions, effectively dispersing and reducing stress concentration, thereby significantly improving the fatigue resistance and service life of the torsion bar under repeated torsional loads.

[0007] In this design, the outer diameter of the first engaging part is equal to the outer diameter of the first shaft segment, the outer diameter of the second engaging part is equal to the outer diameter of the third engaging part and greater than the outer diameter of the second shaft segment, and the outer diameter D of the second shaft segment is greater than the outer diameter d of the first shaft segment. This segmented diameter design achieves a gradient distribution of torsional stiffness, optimizes the torque transmission path, and makes the seat adjustment process smoother and more reliable.

[0008] In a preferred embodiment of the torsion bar, the ratio d / D of the outer diameter d of the first shaft segment and the outer diameter D of the second shaft segment is 0.62 to 0.65. This ratio range ensures that the torsion bar provides sufficient restoring torque to reliably lock the seat angle while also having a good adjustable feel. This avoids the problems of difficult operation due to excessive stiffness in certain areas or loose adjustment due to excessive softness, thereby improving the overall performance and user experience of the seat adjustment system.

[0009] In a preferred embodiment of the torsion bar, the second engaging portion has a positioning portion on the side axially close to the first shaft segment. The outer diameter of the positioning portion is equal to the outer diameter of the second engaging portion. The positioning portion has a first groove and a second groove for positioning. The first groove and the second groove provide a clear and reliable reference for the axial and circumferential positioning of the torsion bar in the seat adjustment mechanism assembly. This structure facilitates quick and accurate installation and positioning during assembly, effectively preventing misinstallation or misalignment, ensuring precise engagement between the engaging portion and the corresponding gear or sleeve, and improving assembly efficiency and quality stability.

[0010] As a preferred embodiment of the torsion bar, the torsion bar is made by cold heading of carbon steel and subsequent stress-relieving annealing, which improves the fatigue resistance of the torsion bar.

[0011] In a preferred embodiment of the torsion bar, the radius of the first rounded transition structure is 1 ± 0.3 mm. This dimension ensures a sufficiently large transition arc to adequately reduce stress concentration, further enhancing the structural reliability of this critical component.

[0012] In a preferred embodiment of the torsion bar, the radius of the second rounded transition structure is 0.5 ± 0.1 mm. This dimension is suitable for connection areas requiring compact design, such as the second engagement section, the second shaft section, and the third engagement section. It can reduce stress concentration within a limited space while ensuring that the effective working length of each functional section (especially the engagement section) is not affected.

[0013] Compared with the prior art, this application has the following beneficial technical effects: through the one-piece molded multi-segment rod structure, the specially set rounded corner transition and the segmented diameter design, stress concentration is significantly reduced and the torque transmission path is optimized, thereby greatly improving the fatigue strength and service life of the torsion bar. Attached Figure Description

[0014] Figure 1 This is a front view of a torsion bar.

[0015] Figure 2 for Figure 1 Sectional view at point AA.

[0016] Figure 3 This is the left view of the torsion bar.

[0017] Figure 4 This is the right view of the torsion bar.

[0018] The following is an explanation of the reference numerals in the attached figures:

[0019] 10. First meshing part;

[0020] 20. First axle segment;

[0021] 30. Second engagement part; 31. First rounded corner transition structure; 32. Positioning part; 33. First groove; 34. Second groove;

[0022] 40. Second axle segment;

[0023] 50. Third meshing part; 51. Second rounded corner transition structure. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0025] In the following embodiments, the same or similar reference numerals denote the same or similar components or components with the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0026] In the description of this utility model, it should be understood that the terms such as center, longitudinal, transverse, length, width, thickness, upper, lower, front, back, left, right, vertical, horizontal, top, bottom, inner, outer, clockwise, and counterclockwise, indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description; therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features shown. In the description of this utility model, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," etc., should be interpreted broadly, and those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0027] Reference Figures 1 to 4This invention provides a high-strength, weather-resistant torsion bar for automotive seats and seat belts. The torsion bar is integrally formed using a cold-forging process, and its material is preferably SWRCH series cold-forging carbon steel, such as SWRCH6A steel, which has good formability and comprehensive mechanical properties. Viewed along the axial direction of the torsion bar (i.e., the direction of its central axis extension), its structure sequentially includes: a first engaging part 10, a first shaft segment 20, a second engaging part 30, a second shaft segment 40, and a third engaging part 50. The first engaging part 10 and the third engaging part 50 are functional parts for cooperating with gears or sleeves in the seat adjustment mechanism to transmit torque; their specific construction can be a spline structure with multiple teeth or a gear structure. The second engaging part 30 is an external spline structure for connecting to the unlocking handle, and can also be a gear structure.

[0028] Specifically, the torsion bar is manufactured using low-carbon alloy steel wire, which is cold-forged into a single piece. The blank is then subjected to stress-relief annealing at 490℃±10℃ for 70 minutes±10 minutes. After annealing, the spline teeth, shaft section, and fillets are precision machined. Following machining, the workpiece undergoes hydrogen embrittlement treatment at 200℃ for 2–4 hours to eliminate the risk of hydrogen embrittlement. Finally, inspection confirms that the burr height of all parts of the finished product is no greater than 0.1mm, ensuring safe and reliable assembly and use.

[0029] At the structural connection, a first rounded transition structure 31 is machined between the first shaft segment 20 and the second meshing portion 30. Second rounded transition structures 51 are machined between the second meshing portion 30 and the second shaft segment 40, and between the second shaft segment 40 and the third meshing portion 50. These rounded transition structures are used to smooth cross-sectional changes and alleviate stress concentration. As a preferred embodiment, the radius of the first rounded transition structure 31 is set to 1 ± 0.3 mm, and the radius of the second rounded transition structure 51 is set to 0.5 ± 0.1 mm.

[0030] Wherein, the outer diameter of the first engaging part 10 is equal to the outer diameter d of the first shaft segment 20 connected to it, the outer diameter of the second engaging part 30 is equal to the outer diameter of the third engaging part 50, and this outer diameter value is greater than the outer diameter D of the second shaft segment 40, which is designed to be greater than the outer diameter d of the first shaft segment 20. Preferably, the ratio d / D of the outer diameter d of the first shaft segment 20 to the outer diameter D of the second shaft segment 40 is controlled in the range of 0.62 to 0.65, for example 0.63 or 0.64. This ratio can better balance torsional stiffness and elasticity.

[0031] Furthermore, a positioning part 32 is integrally formed at one end of the second engaging portion 30 near the first shaft segment 20. The outer diameter of the positioning part 32 is consistent with the outer diameter of the second engaging portion 30. At least two grooves, namely a first groove 33 and a second groove 34, are machined on the circumferential surface of the positioning part 32. These grooves can be used to cooperate with components such as snap rings and positioning pins during assembly to achieve axial and circumferential positioning of the torsion bar in the assembly, preventing rotation and movement.

[0032] The working principle and assembly process of this utility model are briefly described below:

[0033] In the automotive seat angle adjuster, the two engaging ends of the torsion bar mesh with corresponding transmission components. When the seat back angle needs to be adjusted, the torque acting on the torsion bar causes it to elastically twist. Due to its integrated structure and optimized diameter gradient design, supplemented by rounded corners of a specific radius, the stress distribution throughout the bar is more uniform, greatly improving fatigue resistance. The groove on the positioning part 32 engages with the snap-fit ​​on the outer casing, ensuring accurate installation of the torsion bar and reliable operation.

[0034] It should be noted that the specific dimensions, materials, and number of grooves described above are merely examples and are not intended to limit the scope of protection of this utility model. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this utility model should be considered to fall within the protection scope of the claims of this utility model.

[0035] The scope of protection of this utility model includes, but is not limited to, the above embodiments. The scope of protection of this utility model is defined by the claims. Any substitutions, modifications, or improvements to this technology that are easily conceived by those skilled in the art shall fall within the scope of protection of this utility model.

Claims

1. A high-strength, weather-resistant torsion bar for automobile seats and seat belts, characterized in that, The torsion bar is a one-piece rod-shaped structure, which includes, along the axial direction, a first meshing part (10), a first shaft segment (20), a second meshing part (30), a second shaft segment (40), and a third meshing part (50); the first meshing part (10) and the third meshing part (50) are spline structures or gear structures for transmitting torque; a first rounded corner transition structure (31) is provided between the first shaft segment (20) and the second meshing part (30); a second rounded corner transition structure (51) is provided between the second meshing part (30) and the second shaft segment (40) and between the second shaft segment (40) and the third meshing part (50). Wherein, the outer diameter of the first meshing part (10) is equal to the outer diameter of the first shaft segment (20), the outer diameter of the second meshing part (30) is equal to the outer diameter of the third meshing part (50) and is greater than the outer diameter of the second shaft segment (40), and the outer diameter D of the second shaft segment (40) is greater than the outer diameter d of the first shaft segment (20).

2. A high-strength, tough, weather-resistant torsion bar for automobile seats and seat belts according to claim 1, characterized in that, The ratio of the outer diameter d of the first shaft segment (20) to the outer diameter D of the second shaft segment (40) is 0.62 to 0.

65.

3. A high-strength, tough, weather-resistant torsion bar for automobile seats and seat belts according to claim 1, characterized in that, The second engagement part (30) has a positioning part (32) on the side close to the first shaft section (20) along the axial direction. The outer diameter of the positioning part (32) is equal to the outer diameter of the second engagement part (30). The positioning part (32) has a first groove (33) and a second groove (34) for positioning.

4. A high-strength, tough, weather-resistant torsion bar for automobile seats and seat belts according to claim 1, characterized in that, The torsion bar is made by cold heading of carbon steel and subsequent stress-relief annealing.

5. A high-strength, tough, weather-resistant torsion bar for automobile seats and seat belts according to claim 1, characterized in that, The radius of the first rounded transition structure (31) is 1 ± 0.3 mm.

6. A high-strength, tough, weather-resistant torsion bar for automobile seats and seat belts according to claim 1, characterized in that, The radius of the second rounded transition structure (51) is 0.5±0.1mm.

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