JP2010241259A - Vehicle suspension arm - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle suspension arm showing a high durability even if a tailored blank manufactured through welding of plate members having a different thickness from each other is used as a material therefor. <P>SOLUTION: Welding portions 44 kept in a linear state before forming a suspension arm 16 are formed at the suspension arm in such a way that they are positioned at the other of upper and lower locations of both ends in one of upper and lower portions of a central part in a longitudinal direction in regard to a reference plane including a turning axis of each of a vehicle body bearing 30 and a wheel bearing 32 where a compressive stress and a tensile stress are scarcely generated. Accordingly, the welding portions can be positioned at the reference plane or near the reference plane, so that a stress generated at the welding portions having a reduced fatigue strength becomes relatively low and a durability of the suspension arm becomes high. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle suspension arm using a tailored blank material.

  In general, as described in the following patent document, a suspension arm used in a vehicle suspension apparatus is manufactured by using a plate material such as a steel plate as a material and press-molding the plate material. The suspension arm connects the vehicle body and the wheel, and swings with the wheel relative to the vehicle body. Therefore, the suspension arm must be lightweight and strong enough to withstand a large external force. However, since the same strength is not required in all portions of the suspension arm, the entire suspension arm does not have to be made of a plate material having a uniform thickness. The tailored blank material is a single plate material, but has a thick portion and a thin portion, and by using the tailored blank material, the plate thickness is thick at a portion requiring strength. It is possible to manufacture the suspension arm so that the plate thickness is reduced at a portion where the strength is not so required. Therefore, the suspension arm can be light and yet have the necessary strength. Also in the following patent documents, a tailored blank material is used as a material for a suspension arm.

JP 2005-152975 A Japanese Utility Model Publication No. 6-61513

  A tailored blank is generally manufactured by joining a plurality of butted plates together by welding. In the portion where the tailored blank material is welded, there is a possibility that the fatigue strength is reduced due to the influence of heat. If the fatigue strength of the joint portion is lower than that of other portions, the durability of the suspension arm may be impaired. In view of such a situation, an object of the present invention is to provide a highly durable suspension arm while a tailored blank material is used as a material.

  In order to solve the above problems, the suspension arm for a vehicle is arranged such that (A) a first plate member whose both sides extending in the longitudinal direction form a straight line, and (B) a first plate member sandwiched between the first plate member in the width direction, Each is butt-joined to the first plate member by welding, and a tailored blank member made of a pair of second plate members having different thicknesses from the first plate member is used. The arm part formed in a boat shape whose center part is wider than both end parts, one is provided at one end part in the longitudinal direction of the arm part, and the other is provided at the other end part. A suspension arm for a vehicle having a pair of bearing portions that define a dynamic axis, wherein a butt joint line between each of the pair of second plate members and the first plate member is a pair of bearing portions. Two pivot axes defined by With respect to the plane containing, on one of the upper and lower at the central portion in the longitudinal direction, so as to be positioned on the other of the upper and lower both ends, the arm portion is formed.

  When the tailored blank material having a straight butt joint line is formed into a suspension arm having a boat shape whose center in the longitudinal direction is wider than both ends, the butt joint line is deformed from a straight line to a curved line. . On the other hand, in the suspension arm, which will be described in detail later, a compressive stress and a tensile stress are present at a portion located on a plane including the two rotation axes of the arm portion (hereinafter sometimes referred to as “reference plane”). It hardly occurs. In the vehicle suspension arm of the present invention, the curved butt joint line is positioned above or below the reference plane. Therefore, since the butt joint line can be positioned at or near the reference plane, only a relatively small stress can be generated at the butt joint. Therefore, according to the suspension arm of the present invention, although the tailored blank material is used as the material of the suspension arm, the stress generated in the butt joint where the fatigue strength is reduced is relatively small, and the suspension arm has high durability. Can be realized.

It is the schematic of the suspension apparatus comprised including the suspension arm which is an Example of this invention. It is an external view of the suspension arm of an Example. It is a figure for demonstrating the process until the suspension arm of an Example is manufactured from a tailored blank material.

  Hereinafter, as an embodiment for carrying out the present invention, an embodiment of the present invention will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments, and can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

  FIG. 1 is an external view of a vehicle suspension apparatus 10 provided for a rear wheel that is a non-drive wheel. The suspension device 10 is an independent suspension type and is a double wishbone type. The wheel 12 is rotatably held by the axle carrier 14. The axle carrier 14 is rotatably held at one end of each suspension arm such as the lower arm 16, the upper arm 18, and the trailing arm 20. The other end of each suspension arm 16, 18, 20 is rotatably held by the vehicle body. Therefore, the wheel 12 and the axle carrier 14 can swing with respect to the vehicle body. One end of each component of the suspension spring 22, the shock absorber 24, and the torsion bar 26 is attached to the lower arm 16. These parts perform their functions depending on the operation of the lower arm 16 caused by the swinging of the wheels 12 and the axle carrier 14. Incidentally, the lower arm 16 is a suspension arm as an embodiment of the present invention.

  FIG. 2 shows an external view of the lower arm 16. 2A is a plan view and FIG. 2B is a side view. The lower arm 16 includes an arm portion 28, a vehicle body side bearing portion 30, and a wheel side bearing portion 32. In order to allow one end of the suspension spring 22 to be attached to the arm portion 28, the arm portion 28 is formed in a boat shape having a central portion in the longitudinal direction wider than both end portions and opening upward. Further, flanges 34a and 34b are formed along the edge of the opening.

  The lower arm 16 is rotatable with respect to the vehicle body at the vehicle body side bearing portion 30, and is rotatable with respect to the axle carrier 14 at the wheel side bearing portion 32. That is, the wheel 12 and the axle carrier 14 can be swung with respect to the vehicle body by a pair of bearing portions constituted by the vehicle body side bearing portion 30 and the wheel side bearing portion 32. The rotation axes of the vehicle body side bearing portion 30 and the wheel side bearing portion 32 are parallel to each other. Note that a plane including these rotation axes is referred to as a reference plane.

  The lower arm 16 uses a tailored blank 38 as a material. FIG. 3A shows a first plate member and a pair of second plate members that constitute the tailored blank member 38. The pair of second plate members is the thick plate member 40, and the first plate member is the thin plate member 42. They are all carbon steel sheets. Further, the plate thickness of the thick plate member 40 is larger than the plate thickness of the thin plate member 42. In the width direction of the tailored blank material 38, the thin plate material 42 is disposed at the center. The pair of thick plate members 40 are abutted against the thin plate member 42 on both sides extending in the longitudinal direction thereof, and are joined by laser welding. This welded portion is referred to as a welded portion 44. The welded portion 44 is located on the butt joint line in the tailored blank material 38. As shown in FIG. 3B, the butt joint line has a linear shape because it is easy to cut the plate material and align the plate materials.

  The tailored blank material 38 is formed into a predetermined shape by drawing, and then the excess portion is cut off to produce the arm portion 28. In FIG.3 (b), the external shape of the part which remains as the arm part 28 among the tailored blank materials 38, ie, the arm part 28 before drawing, is typically shown by the virtual line (two-dot chain line). . The arm portion 28 is further drilled, and thereafter, the vehicle body side bearing portion 30 and the wheel side bearing portion 32 are welded to both end portions, and the lower arm 16 shown in FIG. 3C is completed.

  The strength required for the lower arm 16 varies depending on the portion of the lower arm 16. Therefore, the dimensions of the thick plate member 40 and the thin plate member 42 are determined in advance so that the thick plate member 40 and the thin plate member 42 are arranged at appropriate portions according to the required strength. In the lower arm 16, since the flange portions 34a and 34b require high strength, the thick plate material 40 is disposed on the flange portions 34a and 34b. Moreover, since high intensity | strength is not required in parts other than a flange part, the thin plate material 42 is arrange | positioned in the part. The lower arm 16 configured as described above has a necessary strength while being lightweight.

  As shown in FIG. 2 (b), the welded portion 44, that is, the butt joint line, is deformed into a curve below the reference plane at the center and above the reference plane at both ends. . Below, generation | occurrence | production of the stress in the welding part 44 deform | transformed into such a curve is demonstrated.

  When the vehicle travels, the lower arm 16 swings around the vehicle body side bearing portion 30. That is, an external force that swings the lower arm 16 is applied to the lower arm 16. On the other hand, an external force in the opposite direction acts on the arm portion 28 from the suspension spring 22, the shock absorber 24, and the torsion bar 26. For example, as shown in FIG. 2B, when an upward external force is applied from the wheel 12 to the vehicle-side bearing portion 32 with the vehicle body-side bearing portion 30 as a fulcrum, the arm portion 28 receives from the suspension spring 22 or the like. Opposing external force acts. As a result, a bending force acts on the lower arm 16, and due to the bending force, stress in the compression direction is generated on the upper portion of the lower arm 16 in parallel with the reference plane, while on the lower surface of the lower arm 16. Generates a stress in the tensile direction parallel to the reference plane. When a downward external force is applied to the vehicle-side bearing portion 32, conversely, tensile stress is generated in the upper part of the lower arm 16 in parallel with the reference plane, and in the lower part of the lower arm 16 in parallel with the reference plane. Compressive stress is generated. However, in either case, the stress in the compression direction and the tensile direction hardly occur on the reference plane. As described above, when a bending force acts on the lower arm 16, the compressive stress and the tensile stress hardly occur in the reference plane, but increase as the distance from the reference plane increases.

  Considering that such compressive stress and tensile stress are generated in the lower arm 16, if the welded portion 44 having a reduced fatigue strength is disposed in a portion where the stress is large, the durability of the suspension arm 16 is impaired. End up. In the lower arm 16, the welding portion 44 is positioned above the reference plane in the vicinity of the vehicle body side bearing portion 30 and the wheel side bearing portion 32, and the center between the vehicle body side bearing portion 30 and the wheel side bearing portion 32. In the section, the dimensions of the thick plate material 40 and the thin plate material 42 are determined in advance so as to form a curved line positioned below the reference plane. Accordingly, since the welded portion 44 can be positioned on the reference plane where almost no compressive stress and tensile stress are generated, and in the vicinity thereof, the stress generated in the welded portion 44 having a reduced fatigue strength is relatively small. It becomes. As a result, the lower arm 16 has high durability while the tailored blank material is used as a material.

  The suspension arm has been used with its upper part opened, but it can also be used as a suspension arm that opens downward. That is, the suspension arm manufactured in the same manner as described above can be used upside down. In that case, the welded portion is positioned upward in the central portion in the longitudinal direction and downward in both end portions. Even in that case, since the welded portion can be positioned at or near the reference plane, the stress generated in the welded portion becomes relatively small.

  In the above suspension arm, a tailored blank material in which a thin plate material is arranged at the center and a pair of thick plate materials on both sides thereof is used. It is also possible to use a blank material. Even in such a case, the arm portion is formed so that the butt joint line is positioned at one of the upper side and the lower side at the center portion in the longitudinal direction of the suspension arm and at the other of the upper side and the lower side at both ends. For example, the stress generated in the welded portion becomes relatively small.

  16: Lower arm 28: Arm part 30: Car body side bearing part 32: Wheel side bearing part 34a, 34b: Flange part 38: Tailored blank material 40: Thick plate material 42: Thin plate material 44: Welded part

Claims (1)

A first plate member in which both sides extending in the longitudinal direction form a straight line and a first plate member arranged in the width direction with the first plate member sandwiched therebetween, and each butt-joined to the first plate member by welding. And a tailored blank material made of a pair of second plate members having different thicknesses, and the tailored blank material is formed into a boat shape having a center portion in the longitudinal direction wider than both ends. When,
A suspension arm for a vehicle comprising a pair of bearing portions, one of which is provided at one end in the longitudinal direction of the arm portion and the other at the other end, each defining a rotation axis parallel to each other;
A butt joint line between each of the pair of second plate members and the first plate member is in a longitudinal direction with respect to a plane including two rotation axes defined by each of the pair of bearing portions. A suspension arm for a vehicle, wherein the arm portion is formed so as to be positioned at one of the upper side and the lower side at a central portion and at the other side of the upper side and the lower side at both end portions.

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