JP2005104317A - A-form suspension arm for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an A-form suspension arm for a vehicle structured without using a bushing pressure fit member (for example, cylindrical) to be attached fast to the tip of each arm (for example, by welding). <P>SOLUTION: The A-form suspension arm for the vehicle is formed by subjecting a plate member to press working, and at its two forefront parts, through holes are provided for pressure fit of a bushing in such a way as penetrating the two confronting surfaces of the cross-section. The shape of the cross-section is designed so as to generate a residual compression stress of a size to cancel the tensile stress predicted to be generated in the suspension arm while the vehicle is running (caused by application of a front-rear G due to the braking force and/or driving force) when the bushing is fitted by pressure into the through holes. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention generally relates to a so-called A-shaped arm mainly used as an upper arm in a double wishbone type vehicle suspension, and more particularly, to an A-shaped suspension arm formed from a plate-like member by pressing.

Conventionally, an A-type suspension arm for a vehicle formed by pressing so as to have a substantially U-shaped cross section from a plate-like member is known (for example, see Patent Document 1).
JP-A-8-318722

  In the conventional A-type suspension arm described in Patent Document 1, a cylindrical member for press-fitting a bush into each arm tip is fixed by welding.

  The present invention eliminates the welding process at the time of manufacture, and reduces the weight of the suspension arm and reduces the cost, so that it is unnecessary to attach a member for press-fitting the bush as described above. The main purpose is to provide

  A first aspect of the present invention for achieving the above object is an A-type suspension arm for a vehicle formed by pressing a plate-like member, and two surfaces facing in cross section at both arm tip portions. This is an A-type suspension arm for a vehicle provided with a through-hole for press-fitting a bush so as to penetrate through.

  In this embodiment, the “transverse section” refers to a cross section when cut along a plane perpendicular to the arm longitudinal direction.

  According to this aspect, the hole for press-fitting the bush is provided in the arm main body formed by press working, so that the member (for example, cylindrical) for press-fitting the bush is fixed to the tip of the arm (for example, by welding). There is no need.

  In this aspect, the cross-sectional shape of the A-type suspension arm is determined when the bush is press-fitted into the through-hole while the vehicle is running (by applying a longitudinal force G due to braking force or driving force). It is preferable to design the residual compressive stress so as to cancel out the tensile stress that is predicted to occur because the fatigue strength of the arm can be improved without increasing the plate thickness or weight.

  The residual compressive stress is, for example, the shape of the cross section is not the same as the center axis of the through hole provided in the two opposite surfaces when the A-type suspension arm is molded, and the bush Can be applied by designing so as to be matched by press-fitting into the through hole.

  In this case, the central axes of the through holes respectively provided on the two opposite surfaces may be designed to 1) intersect when the A-shaped suspension arm is molded, or 2) You may design so that it may shift | deviate in parallel (for example, the central axis of the side which wants to generate | occur | produce a residual compressive stress is shifted | deviated to the said one direction side).

  ADVANTAGE OF THE INVENTION According to this invention, the A-type suspension arm for vehicles made into the structure which does not require the bush press-fitting member (for example, cylindrical) fixed to each front-end | tip part of an arm (for example by welding) can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings. Since the basic concept of the double wishbone type vehicle suspension, the main hardware configuration and the operating principle, and how the A-shaped arm is used therein are known to those skilled in the art. Detailed explanation is omitted.

  First, an A-type suspension arm according to an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a perspective view schematically showing an appearance of a vehicle-type A suspension arm 100 according to the present embodiment. The A-shaped arm 100 is formed by pressing a plate-like member and has a substantially U-shaped cross section. Both tip portions of the substantially U-shaped cross section are bent inward, that is, in a direction approaching each other, in order to increase rigidity.

  The A-shaped arm 100 is provided with a hole 101 to which a ball joint (not shown) serving as a fulcrum for arm swinging when mounted on a vehicle is attached.

  A hole 102 for press-fitting a bush is formed at the tip of both arms of the A-shaped arm 100. The bush press-fitting hole 102 is formed by punching four holes in a plate-like member and then pressing it into a substantially U-shape.

  A flange 103 is formed on the inner side (four locations) of the bush press-fitting hole 102 over the entire circumference of the hole 102. The inner peripheral surface of the flange 103 is pressed from the outer peripheral surface of the press-fitted bush and supports this.

  FIG. 2 is a top view showing an outline of the vehicle A-type suspension arm 100 according to this embodiment. As shown in the drawing, the left direction in the drawing is the vehicle front direction when assembled to the vehicle, and the right direction is the vehicle rear direction. Further, the illustrated arm shape is merely an example, and those skilled in the art can appropriately design it.

In the figure, F ₁ represents a force (G) applied to the A-shaped arm 100 (fulcrum) by the braking force during traveling of the vehicle, and F ₂ is applied to the A-shaped arm 100 (fulcrum) by the driving force during traveling of the vehicle. Represents force (G). An arrow A represents a bush press-fitting direction into the bush press-fitting hole 102.

  FIG. 3 is a partial longitudinal sectional view of one arm tip portion surrounded by a circle B in FIG. 2 when the bush 301 is press-fitted into the A-shaped arm 100.

  As shown in the figure, the bush 301 is provided with a step whose outer diameter changes at a longitudinal position that does not come into contact with the flange 103 when press-fitted, and the outer diameter at the front end side in the press-fitting direction is designed to be slightly smaller. . In addition, the bush press-fit hole 102 is designed such that the inner diameter Φ1 on the side inserted first is larger than the inner diameter Φ2 on the side inserted later (Φ1> Φ2).

  A substantially half of the rear end side of the bush 301 in the longitudinal direction has an outer diameter having an appropriate press-fitting allowance with Φ1 of the bush press-fitting hole 102, and an approximately half of the front end side has an appropriate press-fitting allowance with Φ2. Has an outer diameter. Therefore, even if the substantially half of the front end side of the bush 301 passes through the bush press-fitting hole 102 having the inner diameter Φ1 before the substantially half of the rear end side, the flange 103 is not excessively pressed by the bush 301, and the rear end side substantially An appropriate press-fitting allowance relationship between the half and the inner diameter Φ1 is maintained.

  Next, the distortion (stress) predicted to occur in the A-arm 100 during traveling of the vehicle will be described with reference to FIGS. 4 is a partially enlarged view of one arm tip portion surrounded by a circle B in FIG.

4 shows a compressive strain b which is expected to occur when the braking force F ₁ in FIG. 2 is applied to the A-arm 100, c and tensile strain a, the d show schematically. As shown in the figure, since the A-shaped arm 100 has a certain thickness, the direction of the stress generated outside and inside the plate is reversed.

Further, FIG. 5 (a) and (b), schematically the direction and magnitude of the distortion a~d caused when the braking force F ₁ and the driving force F ₂ in FIG. 2 is applied to the A-arm 100, respectively Shown in As shown in the figure, if the direction of the applied force is reversed, the direction of distortion generated is also reversed. Further, since the braking force F ₁ and the driving force F ₂ are generally larger than the braking force F ₁ (F ₁ > F ₂ ), the average stress is higher when the braking force F ₁ is applied. . Further, in the same region, a larger stress is generated in the plate having a smaller R than the outside of the plate.

Since in general a large influence on fatigue strength better tensile than the compressive strain strain, in order to improve the fatigue strength of the A-arm 100, the largest tensile strain when braking force F ₁ is applied It can be seen that the portion a in FIG. Therefore, in this embodiment, it grants advance actively residual strain of the compression side to the portion of the a, reduce the average strain when braking force F ₁ is exerted during travel.

  A specific method will be described with reference to FIG. 6 shows the C tip of FIG. 2 for the tip of one arm of the A-shaped arm 100, FIG. 6 (a) shows the state before the bush press-fitting, and FIG. 6 (b) shows the state after the bush press-fitting.

  As shown in FIG. 6 (a), when the A-shaped arm 100 according to the present embodiment is formed from a plate-like member, the two opposite faces are opened downward, particularly in the cross section of the arm tip portion. So that it is pressed. In other words, the opposing surfaces where the bush press-fit holes 102 are provided are tilted so that the central axes of the bush press-fit holes 102 that form a pair intersect each other before the bush press-fit.

  When the bush 301 is press-fitted into the A-shaped arm 100 formed in such a shape from the direction A, as shown in FIG. 6 (b), the opposite faces on which the bush press-fitting holes 102 are provided are perpendicular to each other in the press-fitted state. The central axis of the bush press-fit hole 102 is also aligned. Due to this press-fitting, in the state where the bush 301 is press-fitted, a compressive residual stress is generated in a portion indicated by a 'in FIG.

Thus bushing mounted at pre-granted residual compressive strain a a 'reduces this cancel each other and the tensile may be caused by the braking force F ₁ in the vehicle traveling strain a (see FIG. 4).

  Therefore, according to the present embodiment, by providing the bush press-fitting hole 102 in the A-shaped arm 100 itself, a bush press-fitting member (for example, cylindrical) fixed to the tip of the arm (for example, by welding) becomes unnecessary. At the same time, the fatigue strength of the A-arm 100 against tensile strain that may occur during vehicle travel can be increased.

In this embodiment, in FIG. 6 (a), for convenience, the opposing both surfaces where the bush press-fitting holes 102 are provided are shown to be opened to the left and right at substantially the same angle from the vertical center line, but this is only an example. _First , the opening angle can be arbitrarily set based on the magnitude of the tensile stress caused by the predicted braking force F1, the ease of manufacturing and bushing pressurization, and the left and right may not be symmetrical. It is preferred that the angle be sufficient to provide a residual compressive stress sufficient to counteract the maximum tensile stress expected to occur during vehicle travel.

  2 to 4, the cross-sectional shape opened downward in FIG. 6A is not shown for convenience, and in FIG. 6B, the bush shown in FIG. 3 as an example. The detailed shape of 301 is omitted for convenience.

  Next, an A-shaped arm according to another embodiment of the present invention will be described. The A-shaped arm according to the present embodiment has substantially the same shape as that of the first embodiment, and is provided with the bush press-fit hole 102 in the A-shaped arm 100 itself, however, as shown in FIG. Due to the cross-sectional shape different from that, residual compressive strain is applied to a place where tensile strain is expected to occur during vehicle travel.

  FIG. 7 shows the cross-sectional shape according to the present embodiment, which is an alternative to the cross-section of the A-shaped arm shown in FIG. 6, as seen from the C view of FIG. 2, and FIG. FIG. 7B shows a state after the bush press-fitting.

  In the present embodiment, as shown in FIG. 7A, the cross-sectional shape at the tip of one arm of the A-shaped arm 100 is such that both opposing surfaces provided with the bush press-fitting holes 102 are substantially parallel in the vertical direction. However, the central axis of the bush press-fitting hole 102 is shifted in parallel. More specifically, the central axis on the side where compression strain is to be applied in advance is shifted downward.

  When the bush 301 is press-fitted into the A-shaped arm 100 formed in such a shape from the direction A, as shown in FIG. 7B, the center axis of the bush press-fit hole 102 coincides with the press-fitted state, and the embodiment As in the case of No. 1, a residual stress on the compression side is generated in the portion indicated by a ′ in FIG.

Thus bushing mounted at pre-granted residual compressive strain a a 'reduces this cancel each other and the tensile may be caused by the braking force F ₁ in the vehicle traveling strain a (see FIG. 4).

  Therefore, according to the present embodiment, by providing the bush press-fitting hole 102 in the A-shaped arm 100 itself, a bush press-fitting member (for example, cylindrical) fixed to the tip of the arm (for example, by welding) becomes unnecessary. At the same time, the fatigue strength of the A-arm 100 against tensile strain that may occur during vehicle travel can be increased.

  The best mode for carrying out the present invention has been described by giving two embodiments. However, as will be apparent to those skilled in the art, the first and second embodiments are merely examples, and the present invention is not limited to other embodiments. It is also possible to implement this.

  For example, in Examples 1 and 2 above, the shape when the tip of the arm is viewed in the horizontal direction (view C in FIG. 2) is an initial shape devised so that residual compressive strain is generated at a desired location by bushing. However, the direction of the residual compressive strain given in advance is not limited to the cases of FIGS. For example, the shape when the arm tip is viewed from above as shown in FIG. 2 may be an initial shape such that the center line of the bush press-fit hole intersects, or the center line of the bush press-fit hole is shifted in parallel. An initial shape may be used.

  Also, the shapes of the A-shaped arms shown in the attached drawings are all shown schematically for explaining the features of the present invention, and the present invention is not limited to these shapes. According to the present invention, 1) a bushing press-fitting hole is provided in an A-shaped arm itself formed by press working, and 2) a residual compressive strain is applied in advance so as to cancel a tensile strain that is expected to occur during traveling of the vehicle. Any type of A-shaped arm can be used.

  Further, in the above two embodiments, for convenience, the shape of the A-type suspension arm has been described by focusing on one tip portion. However, as will be apparent to those skilled in the art, the above embodiment is also applied to the other tip portion. It is clear that the shapes described in 1 and 2 are applied as they are after mirror inversion.

  The A-type suspension arm according to the present invention can be used as an upper arm in a double wishbone type vehicle suspension. The type, appearance, weight, size, running performance, etc. of the vehicle to be mounted are not limited.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view schematically showing an external appearance of a vehicle type A suspension arm according to an embodiment of the present invention. It is a top view which shows the outline of the A-type suspension arm for vehicles which concerns on one Example of this invention. It is a fragmentary longitudinal cross-sectional view which shows roughly the one front-end | tip part of the A-type suspension arm for vehicles which concerns on one Example of this invention of the state in which the bush was press-fitted. It is the elements on larger scale which show schematically one front-end | tip part of the A-type suspension arm for vehicles which concerns on one Example of this invention which showed typically the distortion which may arise during vehicle travel. (A) It is a graph which shows roughly the magnitude | size of the distortion which may arise by the braking force during vehicle driving | running | working in each place shown in FIG. (B) It is a graph which shows roughly the magnitude | size of the distortion which may arise by the driving force during vehicle driving | running | working in each place shown in FIG. (A) It is the schematic which shows the C view of FIG. 2 of the A-type suspension arm for vehicles which concerns on one Example of this invention before a bush is press-fitted. (B) It is the schematic which shows the C view of FIG. 2 of the A-type suspension arm for vehicles which concerns on one Example of this invention after a bush is press-fitted. (A) It is the schematic which shows the C view of FIG. 2 of the A-type suspension arm for vehicles which concerns on another one Example of this invention before a bush is press-fitted. (B) It is the schematic which shows the C view of FIG. 2 of the A-type suspension arm for vehicles which concerns on another one Example of this invention after the bush was press-fitted.

Explanation of symbols

100 A-type suspension arm 101 Ball join mounting hole 102 Bush press-fit hole 103 Flange 301 Bush

Claims (6)

An A-type suspension arm for a vehicle formed by pressing a plate-shaped member,
An A-type suspension arm for a vehicle, characterized in that a through-hole for press-fitting a bush is provided at both arm tip portions so as to penetrate two surfaces facing each other in a cross section. The A-type suspension arm for a vehicle according to claim 1,
The cross-sectional shape is designed so that when the bush is press-fitted into the through-hole, residual compressive stress is generated that counteracts the tensile stress expected to occur in the A-type suspension arm during vehicle travel. An A-type suspension arm for a vehicle. An A-type suspension arm for a vehicle according to claim 2,
The shape of the cross section is not the same as the center axis of the through hole provided on the two opposite surfaces when the A-shaped suspension arm is molded, and the bush is press-fitted into the through hole. A type suspension arm for a vehicle, which is designed so as to be matched with each other. An A-type suspension arm for a vehicle according to claim 3,
The vehicle-shaped A-type suspension arm is characterized in that the shape of the cross section is designed so that the central axis intersects when the A-type suspension arm is molded. An A-type suspension arm for a vehicle according to claim 3,
The vehicle A-type suspension arm is characterized in that the cross-sectional shape is designed so that the central axis is shifted in parallel when the A-type suspension arm is molded. The vehicle-type A suspension arm according to claim 5,
An A-type suspension arm for a vehicle, wherein a central axis of the central axis on which a residual compressive stress is to be generated is shifted to the one direction side.

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