Vehicle body fastening part structure

Abstract

To enable stability of welding quality to be maintained without deteriorating rigidity of a fastening part between a vehicle body frame and a subframe even when a nut is coupled to the vehicle body frame by spot-welding.SOLUTION: A vehicle body fastening part structure includes: a vehicle body frame; a subframe attached to the vehicle body frame; a welding pipe nut coupled to the vehicle body frame; and a bolt fastening the subframe to the welding pipe nut. The welding pipe nut includes: a pipe portion inserted into the vehicle body frame from the outside; a coupling flange portion formed at a base of the pipe portion and coupled to the outer surface of the vehicle body frame by spot-welding; and a boss portion disposed in a protruding manner on the surface of the coupling flange portion facing the pipe portion. A seating surface is disposed at an end surface of the boss portion, and the subframe is fastened in contact with the seating surface.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present invention relates to a vehicle body fastening structure. [Background technology]

[0002] If the rigidity of the fastening parts is improved when fastening the subframe to the vehicle frame, for example when the subframe is a suspension cross member, the input from the road surface that the suspension receives can be transmitted smoothly to the vehicle body, thereby improving delays in steering response, etc.

[0003] Conventionally, for example, the mounting portion of a suspension cross member is abutted against the underside of the vehicle body frame and fastened by a bolt to a nut welded to the vehicle body frame. In many cases, this nut is welded to the surface of the vehicle body frame opposite the mounting portion of the suspension cross member. In many cases, a spot welding nut is used as the nut.

[0004] When spot welding a spot welding nut to a vehicle frame, the joining surface of the spot welding nut and the vehicle frame are sandwiched between electrodes, and the joining portion is melted by heat generated by electrical resistance. When the melted portion is cooled, a nugget is formed, and this nugget joins the joining surface of the spot welding nut to the vehicle frame.

[0005] A depression (dent) is formed due to thermal deformation at the portion of the vehicle frame and the spot welding nut where the electrode is pressed. A slightly raised indentation is then formed around this depression. When the mounting portion of the suspension cross member is abutted against the vehicle frame and fastened with a bolt, this mounting portion is pressed against the indentation portion formed on the vehicle frame. Because the indentation portion is raised from the vehicle frame, the mounting portion is fastened in a state where it rides up on the indentation portion.

[0006] If the mounting part is fastened while resting on the indentation, the mounting part will be floating apart from the joint surface of the vehicle frame, reducing the fastening rigidity. If the mounting part of the suspension cross member is twisted due to the suspension stroke or vibration of the power unit (engine, electric motor), stress in the twisting direction (direction perpendicular to the center line) will be easily concentrated at the fastening part between the mounting part and the indentation.

[0007] The height of the indentation varies from spot weld to spot weld. If the height of the indentation is high, the rigidity of the fastening part is further reduced, which leads to reduced handling stability, ride comfort, and steering response.

[0008] For example, Patent Document 1 (Japanese Patent No. 6337342) discloses a technique in which a pipe nut is inserted from below into a through hole drilled in a vehicle body frame so that a flange portion formed at the base end is brought into contact with the underside of the vehicle body frame, and the outer periphery of this flange portion is joined by arc welding.

[0009] The technique disclosed in this document allows almost the entire surface of the flange portion formed at the base of the pipe nut to be joined to the vehicle frame, thereby improving the rigidity of the fastening portion. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 6337342 Summary of the Invention [Problem to be solved by the invention]

[0011] However, in the technology disclosed in Patent Document 1, the flange portion formed on the pipe nut is joined to the vehicle frame by arc welding, but arc welding has a problem in that the welding quality is less stable than spot welding.

[0012] Furthermore, arc welding generates spatter during welding. This flange portion has a seating surface against which the mounting portion of the suspension cross member abuts. Therefore, during arc welding, it is necessary to protect this seating surface with a masking material to prevent spatter from adhering. In order to protect the seating surface of the flange portion with a masking material, a separate process of attaching and detaching the masking material is required before and after the arc welding process. The technology disclosed in Patent Document 1 requires a separate process of attaching and detaching the masking material, which increases the number of work steps and causes a disadvantage of reducing production efficiency.

[0013] The present invention aims to provide a vehicle body fastening structure that not only maintains stability of welding quality but also has good productivity without reducing the rigidity of the fastening portion between the vehicle body frame and a subframe even when nuts are joined to the vehicle body frame by spot welding. [Means for solving the problem]

[0014] The present invention relates to a vehicle body fastening structure comprising a vehicle body frame provided on a vehicle body, a subframe having an attachment portion attached to the vehicle body frame, a welding pipe nut connected to the vehicle body frame, and a bolt fastening the attachment portion of the subframe to the welding pipe nut, wherein the welding pipe nut has a pipe portion that is inserted into the body frame from the outside and has a female thread portion screwed into it, and a connecting flange portion formed at a base of the pipe portion and connected to an outer surface of the vehicle body frame, and the mounting portion of the subframe is fastened to the welding pipe nut by a bolt screwed into the female thread portion, the connecting flange portion is connected to the outer surface of the vehicle body frame by spot welding, a boss portion protrudes from a surface of the connecting flange portion that faces the pipe portion across the connecting flange portion, a seat surface is provided on an end surface of the boss portion, and the mounting portion of the subframe abuts against the seat surface and is fastened by the bolt. Effect of the Invention

[0015] According to the present invention, a connecting flange formed at the base of a pipe part provided on a weld pipe nut is connected to the outer surface of a body frame by spot welding, a boss is provided on the surface of the connecting flange opposite the pipe part, a seat is provided with a mounting part of a subframe that abuts against the boss to provide a seat, and the mounting part is fastened to the seat by a bolt, so that the mounting part can be fastened by abutting the surface of the seat without being affected by the indentation formed by spot welding. As a result, the rigidity of the fastening part between the body frame and the subframe is not reduced, the stability of the welding quality can be maintained, and good productivity can be obtained. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is an exploded perspective view of a vehicle front frame and a suspension cross member according to a first embodiment; [Diagram 2] FIG. 2 is a front view of the main part of the front frame of the vehicle. [Diagram 3] FIG. 13 is a perspective view showing a state in which a spot welding pipe nut and a separator are joined to a front side frame in the first embodiment; [Figure 4] Enlarged view of part IV in Fig. 3 [Diagram 5] FIG. 4 is a perspective view showing a state in which the separator is removed from FIG. 3. [Figure 6] Enlarged view of part VI in Fig. 5 [Figure 7] FIG. [Figure 8] FIG. 2 is a perspective view of the spot welding pipe nut from diagonally above. [Figure 9] FIG. 2 is a perspective view of the spot welding pipe nut from diagonally below. [Figure 10] XX cross-sectional view of FIG. 8 [Figure 11] XI-XI cross-sectional view of FIG. 4 [Figure 12] 11, XII-XII cross-sectional view [Figure 13] 3 according to a second embodiment. [Figure 14] 13, XIV-XIV cross-sectional view [Figure 15] 14, XV-XV cross-sectional view DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. [First embodiment] A first embodiment of the present invention is shown in Figs. 1 to 12. Reference numeral 1 in Figs. 1 and 2 denotes the front body of a vehicle. A power unit room 2 is provided in this front body 1. This power unit room 2 is separated from a cabin 3 at the rear by a toe board 4. In the following description, when "joined" is mentioned, the joining method is assumed to be welding using spot welding, unless otherwise specified. In the drawings, spot welding symbols are attached only to spot welding points indicating characteristic parts, and spot welding symbols are omitted for other spot welding points.

[0018] The power unit room 2 is divided into left and right sides by a front wheel apron 5. A pair of left and right front side frames (hereinafter referred to as "side frames") 6 serving as a vehicle body frame are arranged inside the front wheel apron 5. The side frames 6 extend in the front-rear direction of the vehicle body. The side frames 6 extending rearward are joined to the toe board 4 midway.

[0019] A strut tower 7 is formed at the rear of the front wheel apron 5. A strut-type suspension (hereinafter simply referred to as "suspension") 7 is housed in this strut tower 7. A strut support portion 7a is formed at the top of the strut tower 7. The top of this suspension 8 is supported by the strut support portion 7a via a strut upper mount 8a.

[0020] Further, a suspension cross member (hereinafter referred to as "suspension cross member") 9 serving as a subframe is disposed below the power unit room 2. This suspension cross member 9 is disposed at a position that is substantially aligned with the suspension 8 in the vehicle width direction. The periphery of this suspension cross member 9 is bent downward. Both sides of this suspension cross member 9 in the vehicle width direction are inclined upward. Flat mounting portions 9a are formed on both ends of this suspension cross member 9 in the vehicle width direction. Reinforcements 10 are joined to the back surface of the mounting portions 9a. Although not shown, a power unit such as an engine or an electric motor is supported by this suspension cross member 9 via a power unit mount or the like.

[0021] Arm support parts 9c are provided on the underside of both ends of the suspension chrome member 9 in the vehicle width direction to protrude therefrom. A base part of a suspension lower arm (hereinafter simply referred to as "lower arm") 11 is supported on the arm support part 9c so as to be swingable up and down. The lower part of the suspension 8 is supported on the tip side of the lower arm 11, and a wheel hub (not shown) to which the front wheel FH is fixed is supported so as to be rotatable.

[0022] As shown in Figures 1 to 6, the left and right side frames 6 have an inner frame 12 and an outer frame 13. The inner frame 12 is disposed on the inside in the vehicle width direction, and the outer frame 13 is disposed on the outside in the vehicle width direction. Note that, for convenience, the outer frame 13 of the left side frame 6 is partially omitted in Figure 1.

[0023] The inner frame 12 is formed with a hat-shaped cross section. The outer frame 13 is formed with a hat-shaped cross section that is shallower than the inner frame 12. The opening sides of both frames 12, 13 face each other, and flange portions 12a, 13a formed on the top and bottom are joined to form a closed cross section.

[0024] The rear portions of the left and right side frames 6 have kick sections that gradually decrease in height toward the rear, and these kick sections are joined to the toe board 4. Furthermore, the lower portion of the front wheel apron 5 is joined to the outer surface of the outer frame 13 in the vehicle width direction.

[0025] Mounting portions 9 a formed on both sides of the suspension chrome member 9 in the vehicle width direction are in contact with lower surfaces 12 b of inner frames 12 which are components of the side frames 6 .

[0026] As shown in Fig. 1, a bolt insertion hole 9b is formed in the mounting portion 9a of the suspension chrome member 9. Two bolt insertion holes 9b are formed at a predetermined distance apart in the front-rear direction of the vehicle body. A pipe nut insertion hole 12c is formed in the lower surface 12b of the inner frame 12 corresponding to the bolt insertion hole 9b.

[0027] As shown in Figures 11 and 12, a pipe section 14a of a spot-welding pipe nut 14 is inserted into this pipe nut insertion hole 12c from the outside (from below in the figures), and this pipe section 14a protrudes into the inner frame 12. As shown in Figures 8 and 9, the spot-welding pipe nut 14 has a coupling flange section 14b formed at the base of the pipe section 14a. Furthermore, the spot-welding pipe nut 14 has a boss section 14c protruding from the bottom surface of the coupling flange section 14b.

[0028] The connecting flange portion 14b is formed in a rectangular shape with a predetermined plate thickness. The longitudinal direction of this connecting flange portion 14b extends in the front-rear direction of the vehicle body along the outer surface of the lower side surface 12b of the inner frame 12. The boss portion 14c is formed in an annular shape. The axis of the pipe portion 14a and the center of the boss portion 14c are disposed at the center of the connecting flange portion 14b. A seat surface 14d is provided on the end surface of this boss portion 14c. The mounting portion 9a of the suschrome member 9 abuts against this seat surface 14d.

[0029] As shown in Fig. 10, a bolt insertion hole 14e is drilled through the pipe portion 14a, the connecting flange portion 14b, and the boss portion 14c of the spot welding pipe nut 14. A female thread portion 14f is screwed into the middle of the bolt insertion hole 14e. As shown in Fig. 5 and Fig. 6, the connecting flange portion 14b of the spot welding pipe nut 14 and a flange portion 15b of a separator 15 (described later) are connected in a triple-layer configuration with the lower surface 12b of the inner frame 12 sandwiched therebetween.

[0030] The pipe portion 14a of the spot welding pipe nut 14 is surrounded by a separator 15. As shown in Fig. 7, the separator 15 is made of a metal plate bent into a groove shape in a plan view. The opening side of the separator 15 faces the inner surface 12d in the vehicle width direction of the inner frame 12 (hereinafter referred to as the "frame inner surface"). As shown in Fig. 12, the inner width between the side surfaces 15a of the separator 15 in the vehicle front-rear direction is formed to be the same as or slightly wider than the diameter of the pipe portion 14a.

[0031] Also, a flange portion 15b is formed by bending outward from the upper edge, rear edge, and lower edge of the side surface 15a. This flange portion 15b is joined to the upper side surface 12e, the frame inner surface 12d, and the lower side surface 12b of the inner frame 12. The joining flange portion 14b of the spot welding pipe nut 14 faces the lower surface of this flange portion 15b in the vehicle width direction, sandwiching the lower side surface 12b of the inner frame 12 therebetween. The four corners of the joining flange portion 14b are joined to the lower side surface 12b of the inner frame 12 and the separator 15 in a state where the three sheets are overlapped.

[0032] As shown in Fig. 12, the flange portion 15b of the separator 15 is formed to have approximately the same width as the connecting flange portion 14b formed on the spot-welding pipe nut 14. The outer surface of the separator 15 in the vehicle width direction is in contact with or close to the inner surface of the outer frame 13. The pipe portion 14a provided on the spot-welding pipe nut 14 is sandwiched and connected to the inner surface of the separator 15 in the vehicle front-rear direction and supported. Therefore, even if the pipe portion 14a is subjected to vibrations in the vehicle front-rear direction from the suspension member 9, it is suppressed from falling in the same direction.

[0033] As shown in Figures 11 and 12, the mounting portion 9a of the suschrome member 9 is in contact with the seat surface 14d formed on the boss portion 14c of the spot welding pipe nut 14. The reinforcement 10 connected to the back surface of the mounting portion 9a has a bolt insertion hole 10a formed therein, which penetrates into the bolt insertion hole 9b formed in the mounting portion 9a. Furthermore, a support bracket 18 is in contact with the back surface of the reinforcement 10 via a collar 17. The support bracket 18 has a bolt insertion hole 18a formed therein, which penetrates into the bolt insertion hole 17a formed in the collar 17.

[0034] The suschrome member 9, the reinforcement 10, the collar 17, and the support bracket 18 are integrated in advance. The bolt insertion holes 9b, 10a, 17a, and 18a drilled in the respective parts 9, 10, 17, and 18 are arranged coaxially. In the following description, the bolt insertion holes 9b, 10a, 17a, and 18a in the respective parts 9, 10, 17, and 18 are collectively referred to as through hole A for convenience. In addition, the support bracket 18 holds both ends of a stabilizer extending to the left and right in the vehicle width direction, for example.

[0035] Also, the mounting portion 9a formed on the suscro member 9 is in contact with the seat surface 14d of the spot-welding pipe nut 14. A bolt (hereinafter referred to as a "suscro bolt") 19 that fastens the suscro member 9 from below is inserted into a through hole A drilled in the mounting portion 9a. A threaded portion 19a of the suscro bolt 19 is screwed into a female threaded portion 14f that is screwed into the spot-welding pipe nut 14. The suscro member 9 is fixed to the side frame 6 by fastening the suscro bolt 19.

[0036] In this configuration, the connecting flange portion 14b formed at the base of the spot welding pipe nut 14 abuts against the lower surface 12b of the inner frame 12 and the four corners are connected to the lower surface 12b by spot welding, which not only improves productivity but also maintains stable welding quality for each product. Furthermore, since the connecting flange portion 14b is formed in a rectangular shape that is long in the front-rear direction along the lower surface 12b of the inner frame 12, the connecting flange portion 14b can be fixed to the lower surface 12b of the inner frame 12 over a wide area.

[0037] As a result, even if vibrations in the fore-and-aft direction of the vehicle body are transmitted to spot-welded pipe nut 14 from suspention member 9 during driving, the stress caused by the vibrations can be dispersed over a wide area toward inner frame 12. Because the stress caused by the vibrations is dispersed over a wide area toward inner frame 12, stress concentration on spot-welded pipe nut 14 is avoided. By avoiding stress concentration on spot-welded pipe nut 14, the rigidity of spot-welded pipe nut 14 can be relatively increased.

[0038] Furthermore, this connecting flange portion 14b is connected in a triple-layer configuration to the lower surface 12b of the inner frame 12 and the flange portion 15b of the separator 15 that is in contact with the upper surface of the lower surface 12b. Therefore, even if vibrations from the suschrome member 9 are transmitted to the spot-welded pipe nut 14 during driving, the stress generated by the vibrations can be widely dispersed toward the inner frame 12 and the separator 15. As a result, the rigidity of the spot-welded pipe nut 14 can be increased.

[0039] A boss portion 14c is protruded from the bottom surface of the flange portion 14b of the spot welding pipe nut 14, and a seat surface 14d is formed on the bottom surface of this boss portion 14c. The mounting portion 9a of the suschrome member 9 abuts against this seat surface 14d. When the flange portion 14b is joined to the lower surface 12b of the inner frame 12 by spot welding, a slightly raised indentation is formed around the portion where the electrode is pressed. The mounting portion 9a abuts against the seat surface 14d of the boss portion 14c protruding from the flange portion 14b.

[0040] Therefore, the mounting portion 9a can be brought into face contact with the seat surface 14d without being affected by indentations caused by spot welding. As a result, the mounting portion 9a of the suschrome member 9 can be fastened and fixed to the side frame 6 via the suschrome bolt 19 with high rigidity.

[0041] Furthermore, the flange portion 14b is joined to the inner frame 12 by spot welding. Since spot welding is less likely to cause spatter, it is not necessary to cover the seat surface 14d with a masking material. As a result, the process of attaching and detaching the masking material can be omitted, improving productivity.

[0042] Also, for example, in the production process, if it is found that the seating surface 14d and the mounting portion 9a of the suschrome member 9 are inclined at an angle θ and the surface precision is not satisfactory, the inclination of the angle θ can be easily corrected by cutting or grinding the seating surface 14d of the boss portion 14c using a machining center or the like, thereby reducing the product defect rate.

[0043] Incidentally, it is known that when the mounting portion 9a of the SUSC member 9 is fastened to the pipe nut for spot welding 14 with the SUSC bolt 19, the fastening force (surface pressure) acts on the mounting portion 9a within the range of the influence cone. As shown by the dashed line in Fig. 10, the influence cone is a cone drawn with a half apex angle (e.g., 45°) determined by the material of the pipe nut for spot welding 14, from the effective diameter near the start of threading in the female thread portion 14f screwed into the pipe nut for spot welding 14 toward the seat surface 14d.

[0044] According to the theory of the influence cone, the stress generated in the female thread portion 14f during bolt tightening occurs in a range that spreads in a cone shape with a half apex angle. Therefore, on the bearing surface 14d, the tightening force of the SUSC bolt 19 is difficult to transmit to the area beyond the bottom diameter Db of the influence cone. For example, compared to the bottom diameter Df when the bearing surface is formed on the connecting flange portion 14b, the bottom diameter Df of the bearing surface 14d set on the boss portion 14c is wider by the height from the connecting flange portion 14b. As a result, compared to the case where the connecting flange portion 14b is used as the bearing surface, by using the bottom surface of the boss portion 14c as the bearing surface 14d, the contact area for generating surface pressure between the mounting portion 9a is wider. The tightening rigidity at the contact surface can be increased accordingly. [Second embodiment] A second embodiment of the present invention is shown in Figures 13 to 15. Components similar to those in the first embodiment are given the same reference numerals and descriptions thereof will be simplified or omitted.

[0045] In the first embodiment, the joining flange portion 14b of the spot welding pipe nut 14 is joined to the lower surface 12b of the inner frame 12 and the flange portion 15b of the separator 15 in a triple-layered configuration.

[0046] In contrast, the separator 15 of this embodiment has a cut bottom. The flange portion 15b of the separator 15 is not connected to the lower surface 12b of the inner frame 12, but is connected only to the frame inner surface 12d and the upper surface 12e. The other configurations are the same as those of the first embodiment, so the description will be omitted.

[0047] Depending on the vehicle model, the configuration can be simplified by using the separator 15 as in this embodiment. In addition, during spot welding, the joining flange portion 14b of the spot welding pipe nut 14 and the lower surface 12b of the inner frame 12 are joined by overlapping two sheets.

[0048] The thickness of the two-ply plate between the joint flange portion 14b and the lower surface 12b of the inner frame 12 is thinner than the thickness of the three-ply plate in the first embodiment. Therefore, it is not necessary to increase the welding pressure or welding current compared to spot welding with three-ply plates, making manufacturing easier.

[0049] Incidentally, the present invention is not limited to the above-described embodiment. For example, the body frame is not limited to the side frame 6, and the subframe is not limited to the suspension chrome member 9. [Explanation of symbols]

[0050] 1…Front of the vehicle, 2...Power unit room, 3…cabin, 4…Toe board, 5…Front wheel apron, 6…Front side frame, 7…Strut tower, 7a…Strut support part, 8…Suspension, 8a…Strut upper mount, 9…Suspension cross member, 9a…Mounting part, 9b, 10a, 17a, 18a...Bolt insertion holes, 9c…Arm support part, 10…Reinforcement, 11...Lower arm, 12…Inner frame, 12a, 13a...flange portion, 12b...lower side, 12c...Pipe nut insertion hole, 12d…Inner surface in the vehicle width direction (inner surface of the frame), 12e...Top side, 13…Outer frame, 14...Spot welding pipe nut, 14a…Pipe section, 14b...connecting flange portion, 14c…Boss section, 14d…seat, 14f…Female thread, 15…Separator, 15a...side, 15b...flange portion, 17…Color, 18...Support bracket, 19…Suspension bolt, 19a...Threaded portion, Db,Df…bottom diameter, FH…Front wheel θ…Angle

Claims

1. A vehicle body frame provided on the vehicle body; a subframe having a mounting portion that is attached to the vehicle body frame; A welding pipe nut that is connected to the vehicle body frame; a bolt for fastening the mounting portion of the subframe to the welding pipe nut; Equipped with The weld pipe nut is a pipe portion that is inserted into the vehicle body frame from the outside and has a female thread portion screwed therein; a connecting flange portion formed at a base of the pipe portion and connected to an outer surface of the vehicle body frame; having In a vehicle body fastening structure in which the mounting portion of the subframe is fastened to the weld pipe nut by the bolt screwed into the female thread portion, the connecting flange portion is connected to an outer surface of the vehicle body frame by spot welding, a boss portion is provided on a surface of the connecting flange portion facing the pipe portion with the connecting flange portion interposed therebetween, A seat surface is provided on an end surface of the boss portion, The mounting portion of the subframe is abutted against the seat surface and fastened by the bolts. A vehicle body fastening structure.

2. A separator is provided to cover the pipe portion of the weld pipe nut, A flange portion formed on the separator is joined to the subframe.

2. The vehicle body fastening structure according to claim 1.

3. The joining flange portion of the weld pipe nut is joined by spot welding to the flange portion formed on the separator with the subframe sandwiched therebetween.

3. The vehicle body fastening structure according to claim 2.

4. The connecting flange portion is formed in a rectangular shape, and the longitudinal direction extends along the vehicle body frame.

2. The vehicle body fastening structure according to claim 1.

5. the vehicle body frame is a front side frame provided on the left and right sides of a front portion of the vehicle body in a vehicle width direction, The subframe is a suspension cross member.

5. The vehicle body fastening structure according to claim 1, wherein the vehicle body fastening structure is a fastening structure for a vehicle body.

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