[0001]The present invention relates to control arms of automotive suspension.
Background technique
[0002](Also referred to as a suspension arm) control arm is the arm for controlling the movement of the wheels. To mitigate the impact from the road, ride comfort, of course, is an important component to determine the like driving performance and vehicle height.
[0003]With reference to FIG. 15, illustrating the mounting status of the control arm 1 of the type I in the suspension of the automobile. Figure 15 is a state looking down the control arm 1 from the upper body.
[0004]
　As illustrated in FIG. 15, the control arm 1 is an elongate part which connects the vehicle body (body) 2 and the axle (axle) 3. More specifically, the control arm 1, as well as to position the axle 3 in the longitudinal direction or the lateral direction of the body 2 is a part for enabling the vertical movement of the axle 3 relative to the body 2.
[0005]
　Control arm 1 is, for example, mounted rotatably on the body 2 and the axle 3 via the connecting bracket 4 or the connection tube (not shown). Control arm 1, when the axle 3 is displaced in the vertical direction, by the main body portion is torsionally deformed as to pivot relative to the body 2 and the axle 3, to properly and supple control the movement of the tire 5. This improves the grounding of the tire 5, it is possible to improve the steering stability during turning of the vehicle. Further, it is possible to tire 5 to reduce impact body 2 is subjected when over the bump, such as a sidewalk.
[0006]
　The control arm, there is A-arm having an I-type arm (hereinafter "I arms" hereinafter) 1, and A-shaped profile having an I-shaped profile illustrated in Figure 15. Among, I arm 1, since it is suppressed an increase in manufacturing cost because the structure is simple, is employed in many vehicles, vehicle type especially having a link suspension. The main body of the I arm 1 so far, but a round steel bars or steel have been used, large weight is a round bar steel, costly in steel.
[0007]
　As mentioned above, I arm 1 is a critical component for improving the steering stability and ride comfort. In order to ensure the positioning of the axle 3 in the longitudinal direction or the lateral direction of the body 2, the I arm 1 is required to comprise a predetermined tensile strength and compressive strength. Furthermore, in order to supple displace the axle 3 in the vertical direction, the I arm 1, when the torsional stress with the displacement in the vertical direction of the axle 3 is loaded, flexible and good without causing bending deformation It is required to comprise a characteristic causing torsional deformation. Therefore, so far also inventions devised sectional shape of the I arm 1 have been proposed.
[0008]
　For example, a circular cross section of the I-arm (Patent Document 1), cross-sectional W-shape (Patent Document 2), U-shaped cross section (Patent Documents 3 and 4, see FIG. 14 (b)) have been proposed. Furthermore, the stabilizer at the attachment portion automotive lower arm having a lower arm of a motor vehicle which is substantially cross-shaped vehicle body side mounting portion side is disclosed (patent between the wheel-side mounting portion and the vehicle body side attachment portion of the lower arm main body Document 5, and FIG. 13 (b) refer).
CITATION
Patent Document
[0009]
Patent Document 1: JP 2010-76473 JP
Patent Document 2: JP-T 2004-533355 Patent Publication
Patent Document 3: JP 2009-286325 Patent Publication
Patent Document 4: JP-T 2012-509800 Patent Publication
Patent Document 5: JP 2000-142052 JP
Summary of the Invention
Problems that the Invention is to Solve
[0010]
　As described above, examples were devised various cross-sectional shapes of the I arm has been reported, since the additional steering improved stability and ride comfort is recently strongly demanded, it is required to further reduce torsional stiffness.
[0011]
　The present invention has a high buckling strength and a light weight, and torsional rigidity and to provide a control arm having a good torsional deformation performance low.
Means for Solving the Problems
[0012]
　The present inventors have conducted extensive studies and as a result, by adopting a body portion formed by joining the two V-shaped members to each other at the top, has a high buckling strength and a light weight, and the torsional rigidity is low, a good control arm with torsional deformation performance we are obtained.
[0013]
　The present invention is as follows.
[0014]
　(1) a control arm with a pair of attachment portions which are provided apart from each other, and a body portion connecting the pair of mounting portions extending in a first direction,
　said body portion in the first direction in a cross section perpendicular to the first direction in any position,
　the 1V open toward one side in a V-shape in a second direction perpendicular to the first direction from a first apex and said first top shaped member, and
　includes a second has a top portion and a 2V-shaped member opened from the second top in a V-shape toward the other side in the second direction,
　in the cross section, the said first apex and a second apex portion is bonded,
　in a cross section perpendicular to the first direction of the center position in the first direction of the body portion, the opening angle of the first 1V-shaped member and the second 2V-shaped member, It is respectively 150 ° or less
　Control arm.
[0015]
　(2) the first top and the radius of curvature at the second apex are each 1 ~ 10 mm,
　the control arm according to the above (1).
[0016]
　(3) when the interval in the first direction of said pair of mounting portions is L, the total length of the portion between the first top and the second top portion is joined is L / 20 or more,
　the (1) or control arm according to (2).
[0017]
　(4) a distance in the first direction of the pair of attaching portions when is L, the total length of the portion between the first top and the second top portion is joined is less than L,
　the (1 control arm according to any one of) to (3).
[0018]
　(5) the first 1V-shaped member and the second 2V-shaped member, the tensile strength is constituted by 390MPa grade above steel sheet,
　the control arm according to any one of (1) to (4).
[0019]
　(6) the thickness of the steel sheet is 2 ~ 3 mm,
　control arm according to (5).
Effect of the invention
[0020]
　According to the present invention, it has a high buckling strength and a light weight, and torsional rigidity can be obtained a control arm with good torsional deformation performance low.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021]
[1] Figure 1 (a) is a perspective view of a control arm according to an embodiment of the present invention, FIG. 1 (b) is a diagram for explaining the mounting portion.
[2] Figure 2 (a) is a plan view of a control arm according to an embodiment of the present invention, FIG. 2 (b) is a side view.
FIG. 3 is a diagram for explaining the shape of the body portion in the A-A cross section.
FIG. 4 is a main body portion provided in the control arm according to another embodiment of the present invention, is a diagram for explaining the shape in cross section perpendicular to the first direction.
FIG. 5 is an example of a first top joining method of the second apex portion (a: Flare Welding, b: lap welding) is a diagram for explaining the.
FIG. 6 is a graph showing the relationship between the torsional rigidity and the opening angle alpha.
[7] FIG. 7 is a graph showing the relationship between the opening angle α and buckling strength.
[8] FIG. 8 is a diagram for explaining the structure of the control arm of the Comparative Example 1.
[9] FIG. 9 is a diagram for explaining the structure of the control arm of the Comparative Example 2.
[10] FIG 10 is a diagram for explaining the structure of the control arm of the present invention Example 1.
[11] FIG 11 is a graph showing the evaluation results of the torsional rigidity in the third embodiment.
[12] FIG 12 is a graph showing the evaluation results of the buckling strength in the third embodiment.
[13] FIG 13 is a diagram for explaining the structure of the control arm of Comparative Example 3.
[14] FIG 14 is a diagram for explaining the structure of the control arm of the Comparative Example 4.
[15] FIG 15 is an explanatory view illustrating a mounting condition of type I of the control arm in the suspension of the automobile.
DESCRIPTION OF THE INVENTION
[0022]
　Hereinafter, with reference to the accompanying drawings, a description will be given control arm according to an embodiment of the present invention. Note that the control arm, while the longitudinal direction of the vehicle body of the positioning of the axle connecting the vehicle body and the axle of the motor vehicle, is a part for the axle to allow the displacement in the vertical direction relative to the vehicle body.
[0023]
　Figure 1 (a) is a perspective view of the control arm 10 in accordance with an embodiment of the present invention. Control arm 10 includes a main body portion 11, a pair of mounting portions 12. As shown in FIG. 1 (a), a pair of mounting portions 12 are provided away from each other, the main body portion 11, the first direction extending in the direction (X direction shown in FIG. 1 (a)), a pair connecting the mounting portion 12.
[0024]
　1 (b) is a diagram for explaining the mounting portion 12. Mounting portion 12 is a part for connecting the connecting tube or the connecting bracket. In the present embodiment, the attachment portion 12 has a hollow cylindrical shape, as shown in FIG. 1 (b), the main body portion 11 is joined to the outer peripheral surface 12a of the mounting portion 12. In FIG. 1 (b), it shows a joint 11a between the main body portion 11 and the mounting portion 12 by a dotted line.
[0025]
　2 (a) is a plan view of the control arm 10 in accordance with an embodiment of the present invention, FIG. 2 (b) is a side view. Then, FIG. 3, in the first direction of the center of the main body portion 11, for explaining the shape of the body portion 11 in a cross section perpendicular to the first direction (A-A cross section shown in FIG. 2 (a)) it is a diagram of. As shown in FIG. 3, the main body portion 11 includes first 1V-shaped member 13 and the 2V-shaped member 14, in the A-A cross section, has an X-shape.
[0026]
　The 1V-shaped member 13, in the A-A cross section has a first apex 13a, toward the one side in a second direction perpendicular from the first top part 13a in the first direction (Y direction shown in FIG. 3) It has a shape that opens in a V-shape Te. Similarly, the 2V-shaped member 14, in the A-A cross section, having a second apex portion 14a, has a shape opened from the second apex portion 14a into a V-shape toward the other side in the second direction. Then, in the A-A cross section, it is joined to the first top portion 13a and the second apex portion 14a.
[0027]
　Further, in the A-A cross section, the angle α of opening of the 1V-shaped member 13 1 and the opening angle α of the 2V-shaped member 14 2 is set to 150 ° or less, respectively. The main body portion 11 by having the above shape, controller ROHM arm 10 having a light weight and high buckling strength is obtained.
[0028]
　Angle alpha opening 1 and alpha 2 are preferably equal angles. Further, the first 1V-shaped member 13 and the 2V-shaped member 14, in the A-A cross section, extends a third direction perpendicular to the first direction and the second direction (Z direction shown in FIG. 3) and body it is preferable imaginary straight line passing through the center of the parts 11 are axisymmetrically (3 straight line shown by a chain line) as a symmetric axis. By the first 1V-shaped member 13 and the 2V-shaped member 14 has a good symmetry, and deformability torsional buckling strength is further improved.
[0029]
　Incidentally, V-shaped member need not be exactly symmetrical. Symmetry of the V-shaped member, control arm of the present invention is acceptable as long as the effects exerted by not impaired. Asymmetry by variations due to manufacturing conditions, the asymmetry in the case of design change to suit the vehicle body structure is included in the V-shaped member of the present invention. Part 1V-shaped member and the 2V-shaped member, respectively may be used in combination of each other symmetrically, to one or the other may be used in combination of symmetry, each asymmetric to each other it may be used in combination with those of.
[0030]
　The angle alpha opening 1 and alpha 2 are also meant to include 0 °. In this case, although the cross-sectional shape as shown in FIG. 4, even in such a configuration, since the two members are joined at the top, exhibit excellent buckling strength and torsional deformability .
[0031]
　Furthermore, with reference to FIG. 3, the radius of curvature R of the first apex portion 13a and the second apex portion 14a 1 , R 2 is preferably each 1 ~ 10 mm. The radius of curvature is less than 1 mm, there is a possibility that cracks are generated when forming the V-shaped member. On the other hand, the radius of curvature exceeds 10 mm, not become V-shaped. In the present invention, the radius of curvature refers to the value of the radius of curvature of the wall thickness central portion of the first apex portion 13a and the second top 14a.
[0032]
　In the present embodiment, as shown in FIG. 2 (b), in the region including the center position of the main body portion 11, a first top portion 13a and the second apex portion 14a is joined. When welding the first top portion 13a and the second apex portion 14a at the center position of the main body portion 11, when pressing the material in the welding clamp at both ends of the main body portion 11, the 1V-shaped member 13 and the 2V-shaped equally can be added a load to Jo member 14 is preferred because it is possible to stable welding.
[0033]
　For bonding position is not limited to the above example. The first top portion 13a and the second apex portion 14a, only to be joined at any position in the first direction. However, when welding at endmost position, interfere with the welding portion between the main body portion 11 and the mounting portion 12, the welding stability of the interference portion may deteriorate. Therefore, it is preferable to bond the regions away from the top end than 5 mm.
[0034]
　Also, the first top portion 13a and the second apex portion 14a, need not be joined across the entire length of the body portion 11. By the first apex portion 13a and the second apex portion 14a changes the length of the portion is joined, it is possible to adjust the balance between the torsional rigidity and buckling strength of the control arm 10. That is, it is possible to increase the buckling strength by increasing the junction length, whereas, it is possible to reduce the torsional rigidity by reducing.
[0035]
　The interval in the first direction of the pair of mounting portions 12 when the L, the junction length L between the first apex portion 13a and the second apex 14a W , in order to increase the buckling strength is a L / 20 or more it is preferable. Further, the junction length is small, when a large twisting occurs, stress is concentrated on the joint, the joint portion tends to be peeled off. Therefore, the junction length L W is more preferably 6L / 20 or more. On the other hand, the junction length L W , in order to reduce the torsional rigidity, it is preferable to be less than L, and more preferably 12L / 20 or less.
[0036]
　The bonding between the first apex portion 13a and the second apex portion 14a may be not carried out continuously, or may be intermittently performed. When junction is intermittent, the junction length L W is the total length of the portion are joined.
[0037]
　Figure 5 shows an example of a method of joining the first apex portion 13a and the second apex portion 14a (a: Flare Welding, b: lap welding) is a diagram for explaining the. As shown in FIG. 5 (a), may be to flare welded from both sides in the Z direction to form a flared weld 21, as shown in FIG. 5 (b), performed lap welding in the Y direction, overlapping the weld 22 may be formed. Also, flare welds 21 may be formed only on one side of the Z-direction.
[0038]
　It should be noted, does not regard the presence or absence of the supply of the filler wire. However, when supplying filler wire, the cross-sectional area of ​​the main body portion 11 after welding, and thus to increase than before welding. Because it causes an increase in the increase torsional stiffness of the cross-sectional area, the rate of increase in the cross-sectional area before and after welding is preferably suppressed to 10% or less, and more preferably be suppressed to 5% or less.
[0039]
　Method of joining the first apex portion 13a and the second apex portion 14a is not limited to the above example, laser welding, seam welding may be used an adhesive bonding or the like.
[0040]
　The 1V-shaped member 13 and the 2V-shaped member 14, the tensile strength is preferably constructed by 390MPa or higher grade steel sheets. When using a low tensile strength steel sheet, in order to ensure the necessary strength, it is necessary to use a steel plate thickness is large. However, with the thickness increase is undesirable because the further torsional rigidity increases the weight is increased.
[0041]
　If the tensile strength is used 390MPa grade above steel sheet, it is preferable that the thickness is used thin steel sheet 2 ~ 3 mm. Thickness corrosion resistance is insufficient is less than 2 mm, whereas, there is a possibility that can not be reduced enough torsional rigidity at 3mm or more.
[0042]
　The following examples illustrate the present invention more specifically, the present invention is not limited to these examples.
Example 1
[0043]
　In conditions in which the cross-sectional area of the main body portion 11 is constant, the tensile strength of the main body portion 11 is equal, the first 1V-shaped member 13 against the torsional rigidity and buckling strength opening angle alpha 1 and the 2V-shaped member 14 opening angle Arufa 2 the proper range of, was investigated by analysis by computer simulation. In the present embodiment, the opening angle alpha 1 and alpha 2 was equal value (alpha).
[0044]
　The first 1V-shaped member 13 and the 2V-shaped member 14, plate thickness 2.6 mm, the plate width 30 mm, a hot-rolled steel sheet 440MPa grade, using a press molded product of the radius of curvature 4 mm. The first apex portion 13a and the second apex portion 14a of the 1V-shaped member 13 and the 2V-shaped member 14 are joined over the entire length, and a body portion 11 having an X-shaped cross section. Then, we analyzed the study model control arm comprising a body portion 11. Table 1 summarizes the mechanical properties of the hot-rolled steel sheet.
[0045]
[Table 1]

[0046]
　The opening angle α in a first direction of the center of the main body portion 11 by changing the range of 0 ~ 165 °, gives a rotational displacement to the other end while restraining one end of the main portion 11, the torsion It was to evaluate the stiffness and buckling strength. Note that the total length of the main body portion 11 was set to 230 mm.
[0047]
　Open shows the relationship between the angle α and the torsional rigidity in the graph in FIG. 6, shown graphically in Figure 7 the relationship between the opening angle α and buckling strength.
[0048]
　As shown in FIG. 7, the opening angle α is the buckling strength in 90 ° or more was about 55.5KN. Moreover, the opening angle α is buckling strength be less than 90 ° is about 54KN, the opening angle α is the difference was slight as compared with the case of more than 90 °. That is, the buckling strength in the opening angle α is any angle is good.
[0049]
　In contrast, as shown in FIG. 6, the opening angle α is more than 0.99 °, the torsional rigidity exceeds 5N · m / deg, it resulted in greatly increased.
Example 2
[0050]
　In analysis by computer simulation which was performed in Example 2, open the angle α on which is fixed at 90 °, analysis of buckling strength in the case of changing the bonding length between the first apex portion 13a and the second apex portion 14a It was carried out.
[0051]
　According to the results of numerical analysis, but the buckling strength is 55.5kN when joined over the entire length of the body portion 11, it drops to 44kN otherwise joined at all. The larger junction length is effective for the improvement of the buckling strength. However, the bonding length between the first apex portion 13a and the second apex portion 14a, when the entire length of the main body portion 11 is L, if L / 20 or more, can be secured more buckling strength 47KN, practical it was found no problem.
Example 3
[0052]
　8 to 10 are views for explaining the structure of the control arm of the Comparative Examples 1 and 2 and Inventive Example 1. Control arm 31 of Comparative Example 1, the main body portion 23 has a closed section, the control arm 32 of Comparative Example 2, the body portion 24 has an open cross-sectional shape. Further, controller ROHM arm 33 of the present invention Example 1, the main body portion 25 has an X-shaped cross section.
[0053]
　In any of the control arm 31 to 33, the mounting portion 40 with an outer diameter of 54 mm, an inner diameter of 42mm, carbon steel pipe STKM13A for machine structural length 31 mm. Further, the main body portion 25 of the present invention Example 1, was used 440MPa Kyunetsu rolled steel sheet having a thickness of 2.6mm having mechanical properties shown in Table 1 above.
[0054]
　Considering that the tensile strength of the base material is 440MPa class, the strength of the member is such that a 68KN, was adjusted in thickness and total strip width. Specifically, in Comparative Example 1 Total plate width 53 mm, and thickness 2.8 mm, in Comparative Example 2 Total plate width 60 mm, and thickness 2.6 mm, the present invention Example 1, the total plate width 60 mm, thickness 2 It was .6mm. Incidentally, was 16.8mm diameter in Comparative Example 1, the thickness-direction center position. In the present invention, the total plate width is meant the total amount of the plate width of the plate material used to make the above-mentioned member.
[0055]
　In the present invention Example 1, the total length 230 mm, subjected to press molding against steel plate width 30 mm, is bent at a mid-width position, the 1V-shaped member at a substantially V-shaped cross section with a radius of curvature 4mm in thickness center and after producing the first 2V-shaped member was bonded by performing flare welding from both sides. C over the entire length of the arc welding supplies filler wire, assembled main body portion 25. That is, the total bonded length in the first direction is 230 mm. Body portion 25 has a uniform cross-sectional shape over the entire length in the first direction.
[0056]
　Thereafter, butt mounting portion 40 to the main body portion 25 performs an arc welding over the entire circumference X shape, to produce a control arm 33. Back to the control arm, evaluation of torsional rigidity and buckling strength was. The evaluation results are shown graphically in FIGS. 11 and 12.
[0057]
　As shown in FIG. 11, the torsional stiffness is 64N · m / deg in Comparative Example 1, whereas a 15N · m / deg In Comparative Example 2, the present invention Example 1, 5N · m / deg has largely decreased, good torsional deformation performance was obtained.
[0058]
　Further, as shown in FIG. 12, the buckling strength of the present invention Example 1, it can be seen higher than buckling strength of Comparative Example 1 and Comparative Example 2.
[0059]
　Factors buckling strength is high Invention Example 1, the cross-sectional area include increased influence about 5% by supplying the filler wire. However, even without an increase in cross-sectional area, that comparable degree of buckling and Comparative Examples 1 and 2 can be obtained, was confirmed separately.
Example 4
[0060]
　And control arm of the present invention example 1 shown in FIG. 10 used in Example 3, using controller Rohm arm of Comparative Examples 3 and 4 shown in FIGS. 13 and 14 were subjected to further performance evaluation tests. In addition, the total length of each control arm 33 to 35 was 230mm.
[0061]
　In Comparative Example 3, the plate thickness and 2.6 mm, the strength of the member was adjusted so as to 68KN. In Comparative Example 4, the plate thickness 2.0 mm, the strength of the member was adjusted so as to 76KN. For these control arm, torsional rigidity and the evaluation of buckling strength was performed.
[0062]
　The results of the test, the control arm of the Comparative Example 3, the buckling strength is at 55 kN, a is relatively good performance torsional rigidity 7N · m / deg although exhibiting, torsion compared with control arm of the present invention Example 1 It was the result of deformation performance is poor. Also, the integrally molded control arm, unlike the control arm of the present invention Example 1 comprising two members, since it is impossible to change the junction length, to balance and Ductility torsional buckling strength Can not do it.
[0063]
　The control arm of Comparative Example 4, the buckling strength is 50 kN, relatively good but is a large contact area because it is joined parallel bottom together, the torsional rigidity is high as 31N · m / deg became. Control arm of the present invention Example 1, since the curved portions of the two top are joined, the contact area is small and was found to exhibit good torsional deformation performance.
Industrial Applicability
[0064]
　According to the present invention, it has a high buckling strength and a light weight, and torsional rigidity can be obtained a control arm with good torsional deformation performance low. Therefore, by using a control arm according to the present invention, for good steering stability and ride comfort.
DESCRIPTION OF SYMBOLS
[0065]
10 control arm
11 the body portion
12 mounting portion
12a outer peripheral surface
13 a 1V-shaped member
13a first apex
14 a 2V-shaped member
14a second top

WE CLAIM

A control arm having a pair of attachment portions which are provided apart from each other, and a body portion extending in a first direction connecting the pair of mounting portions,
　said body portion, either in the first direction in a cross section perpendicular to the first direction of the position,
　the 1V-shaped member that opens toward one side in a V-shape in a second direction perpendicular to the first direction from a first apex and said first top , and
　the second comprises a first 2V-shaped member opening has a top portion and from said second apex in a V-shape toward the other side in the second direction,
　in the cross section, the said second top portion and the first top Doo is joined,
　in a cross section perpendicular to the first direction of the center position in the first direction of the body portion, the opening angle of the first 1V-shaped member and the second 2V-shaped member, respectively 150 ° is less than or equal to,
　con Roll arm.
[Requested item 2]
　The first top and the radius of curvature at the second apex are each 1 ~ 10 mm,
　the control arm according to claim 1.
[Requested item 3]
　The interval in the first direction of the pair of attaching portions when is L, the total length of the portion between the first top and the second top portion is joined is L / 20 or more,
　according to claim 1 or control arm according to claim 2.
[Requested item 4]
　The interval in the first direction of the pair of attaching portions when is L, the total length of the portion between the first top and the second top portion is joined is less than L,
　claim from claim 1 control arm according to any one of up to three.
[Requested item 5]
　Wherein the 1V-shaped member and the second 2V-shaped member, the tensile strength is constituted by 390MPa grade above steel sheet,
　the control arm according to any one of claims 1 to 4.
[Requested item 6]
　The thickness of the steel sheet is 2 ~ 3 mm,
　the control arm according to claim 5.