JP2006281953A - Front under-frame for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a front under-frame for a vehicle with sufficiently improved the mounting rigidity of a suspension lower arm against a load input from a vehicle width direction without causing front under-frame interfere with a vehicle body structure disposed on a lower side of a suspension cross member. <P>SOLUTION: The front under-frame 30 is constituted by extending a pair of left and right front arm parts 32 having end parts to which each of the suspension cross member 7 and a front connecting part 16 of the suspension lower arm 15 is connected by making the vicinity of a fixed part 31 fixed at the center part of the suspension cross member 7 as a starting point, and extending a pair of left and right rear arm parts 33 having end parts to which each of rear connecting parts 17 of the suspension lower arm 15 is connected to an oblique rear side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention particularly relates to a vehicle front underframe that is effective in improving the rigidity of a front suspension mounting portion.

  In general, the left and right suspension lower arms constituting the front suspension at the front part of the vehicle body are brackets or the like at two positions on the left and right side frames or a vehicle body member such as a suspension cross member installed between the side frames. It is connected through.

By the way, it is known that the mounting rigidity of the suspension lower arm to the vehicle body greatly contributes to the steering stability and vibration damping performance of the vehicle. For this reason, conventionally, various proposals have been made for the front underframe for stiffening the attachment portion of the suspension lower arm. For example, in Patent Document 1, a sub frame (front under frame) in which a main part is configured by a left and right vertical frame and a horizontal frame installed on these is connected to the lower side of the left and right side frames via a support bracket, A technique in which a suspension lower arm is attached between the side frame and the vertical frame is disclosed.
JP 2000-0131056 A

  However, in the technique disclosed in Patent Document 1 described above, since the horizontal frame is installed between the vertical frames far ahead of the mounting position of the suspension lower arm, the suspension lower arm is attached to the load input in the vehicle width direction. It may be difficult to ensure sufficient rigidity with the lateral frame of the front underframe. Further, if the horizontal frame is to be installed between the left and right vertical frames at the position where the suspension lower arm is mounted, the vehicle body structure such as the exhaust pipe is disposed below the suspension cross member. The problem of interference occurs.

  Furthermore, since the suspension lower arm is connected to the vehicle body member at two positions in the front and rear, it is difficult to sufficiently improve the rigidity of the mounting portion of the suspension lower arm with only the horizontal frame.

  The present invention has been made in view of the above circumstances, and the suspension lower arm has sufficient mounting rigidity for load input from the vehicle width direction without causing interference with the vehicle body structure disposed below the suspension cross member. It is an object of the present invention to provide a vehicle front underframe that can be improved.

  The present invention includes a fixing portion that is installed between left and right side frames extending in the front-rear direction and fixed to a central portion of a suspension cross member that supports left and right suspension lower arms extending in the front-rear direction, and a vicinity of the fixing portion. A pair of left and right front arm portions that extend in the vehicle width direction and respectively connect the front connection portion of the suspension lower arm together with the suspension cross member at the end portion, and an end portion that extends obliquely rearward from the vicinity of the fixed portion And a pair of left and right rear arm portions respectively connecting the rear connection portions of the suspension lower arm.

  According to the vehicle front underframe of the present invention, the suspension lower arm mounting rigidity is sufficient even for load input from the vehicle width direction without causing interference with the vehicle body structure disposed below the suspension cross member. Can be stiffened.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings relate to an embodiment of the present invention, FIG. 1 is a bottom view showing the main part of the front skeleton structure of the vehicle body, FIG. 2 is a front view showing the main part of the front skeleton structure of the vehicle body, and FIG. FIG. 4 is a perspective view of a front underframe, FIG. 5 is an explanatory view showing a simulation result of a load transmission path, and FIG. 6 is a main portion taken along the line II of FIG. 7 is a cross-sectional view of a main part taken along line II-II in FIG. 1, FIG. 8 is a cross-sectional view of a main part showing a modification of FIG. 7, and FIG. 9 is a cross-sectional view of a main part showing a modification of FIG. FIG. 10 is a cross-sectional view of the principal part showing a modification of FIG. 7, FIGS. 11 and 12 are explanatory views showing a reinforcing structure of a bracket connected to the front connecting part of the suspension lower arm, and FIG. 13 is connected to the rear connecting part of the suspension lower arm. It is explanatory drawing which shows the structure of a bracket.

  1-3, the code | symbol 1 shows vehicle bodies, such as a motor vehicle. Side sills 5 are respectively disposed on the left and right side portions of the vehicle body 1, and side frames 6 are connected to front end portions of the side sills 5. A suspension cross member 7 is installed between the left and right side frames 6. 1, reference numeral 8 indicates an engine mounted on the suspension cross member 7, and reference numeral 9 indicates an exhaust pipe (vehicle body structure) extending from the engine 8 and disposed below the suspension cross member 7. .

  Further, in the vicinity of the connecting portion with the side frame 6, the front portion of the suspension lower arm 15 is pivotally supported on the suspension cross member 7 via a front bracket 20 protruding from the lower surface of the suspension cross member 7. . More specifically, as shown in FIGS. 3 and 6, the front bracket 20 has a bifurcated structure including a pair of support plates 20a opposed to the vehicle body 1 in the front-rear direction, and the suspension lower arm is interposed between the support plates 20a. Fifteen front connecting portions 16 are interposed. The front portion of the suspension lower arm 15 is swingable in the vertical direction of the vehicle body 1 by fastening bolts 22a and nuts 22b as fastening members that penetrate the support plate 20a and the front connecting portion 16 in the longitudinal direction of the vehicle body 1. Is pivotally supported.

  On the other hand, in the vicinity of the connecting portion with the side sill 5, the rear portion of the suspension lower arm 15 is pivotally supported on the side frame 6 via a rear bracket 25 protruding from the lower surface of the side frame 6. More specifically, as shown in FIGS. 3 and 7, a bolt 26a as a fastening member is suspended from the rear bracket 25, and the rear connecting portion 17 of the suspension lower arm 15 is passed through the bolt 26a. Yes. Further, a support plate 27 fixed to the side sill 5 is passed through the bolt 26a, and the rear portion of the suspension lower arm 15 is swung in the turning direction of the vehicle body 1 by fastening the bolt 26a and the nut 26b protruding from the support plate 27. It is pivotally supported.

  In such a front structure of the vehicle body 1, the left and right suspension lower arms 15 are further stiffened by the front underframe 30.

  The front underframe 30 includes a fixed portion 31 fixed to the center of the lower surface of the suspension cross member 7, and extends in the vehicle width direction starting from the vicinity of the fixed portion 31, and the front connecting portion 16 of the suspension lower arm 15 at the end. And a pair of left and right rear arm portions 33 extending obliquely rearward from the vicinity of the fixed portion 31 and connected to the rear connecting portion 17 of the suspension lower arm 15 at the end.

  If it demonstrates concretely, the fixing | fixed part 31 will be fixed to the suspension cross member 7 by the bolt fastening of two places of right and left, for example.

  Each front arm part 32 is comprised by the hollow sheet metal member extended in the vehicle width direction, respectively with respect to the fixing | fixed part 31, for example (refer FIG.1, 4). Further, each front arm portion 32 is configured such that a plurality of midway portions are bent to form a gap 35 that allows piping of the exhaust pipe 9 below the suspension cross member 7 (see FIG. 2).

  In addition, the bracket 36 formed at the end of each front arm portion 32 has a bifurcated structure including a pair of support plates 36a facing in the front-rear direction of the vehicle body 1 (see FIGS. 4 and 6). These support plates 36a sandwich the front bracket 20 (support plate 20a) and the front connecting portion 16 and are integrally fastened by bolts 22a and nuts 22b, so that the end portion of the front arm portion 32 is a suspension lower arm. It is connected to 15 front connecting portions 16.

  On the other hand, each rear arm portion 33 is constituted by, for example, a hollow sheet metal member that extends while being expanded obliquely rearward of the vehicle body 1 with respect to the fixed portion 31 (see FIGS. 1 and 4). Further, each rear arm portion 33 is bent at a plurality of locations in the middle thereof to form a gap 40 that allows piping of the exhaust pipe 9 below the suspension cross member 7 (see FIG. 3).

  Moreover, the bracket 41 formed at the end of each rear arm portion 33 has a bifurcated structure including a pair of support plates 41a facing the vertical direction of the vehicle body 1 (see FIG. 7). These support plates 41a are interposed between the rear bracket 25 and the rear connection portion 17 and between the rear connection portion 17 and the support plate 27, and are integrally fastened by bolts 26a and nuts 26b. The end portion of the rear arm portion 33 is connected to the rear connecting portion 17 of the suspension lower arm 15.

  Here, FIG. 5 shows an analysis model in which the plate member 100 is fixed to a rigid member at each fixing point 101 corresponding to each front connecting part 16, each rear connecting part 17, and each fixing part 31 on the vehicle body 1. For example, it is a simulation result showing a path through which a load input from a fixed point 101 corresponding to the right front connecting portion 16 is transmitted on the plate member 100. Although not shown, a simulation is performed when a load is input from the fixed point 101 corresponding to each of the connecting portions 16 and 17 using the same analysis model. In this embodiment, in order to efficiently realize load transmission between the left and right sides of the vehicle body 1, the extending direction of the arms 32 and 33 of the front underframe 30 is a load transmission path that can be derived from the simulation results. It is set in a general direction.

  According to such a form, a pair of left and right front arm portions 32 to which the front connecting portion 16 of the suspension lower arm 15 is connected to the end portion from the vicinity of the fixing portion 31 fixed to the central portion of the suspension cross member 7. And a pair of left and right rear arm portions 33 to which the rear connecting portion 17 of the suspension lower arm 15 is connected to each other to form a front under frame 30, thereby being arranged below the suspension cross member 7. The attachment rigidity of the suspension lower arm 15 can be sufficiently improved even when a load is input from the vehicle width direction without causing interference with the vehicle body structure provided. That is, the front under frame 30 is configured to relay the load input from the suspension lower arm 15 between the left and right sides of the vehicle body 1 through the fixed portion 31, and thus the length of the individual arm portions 32 and 33 is configured to be short. Even when the escape portions for the exhaust pipe 9 and the like are formed in the arm portions 32 and 33, the strength of the arm portions 32 and 33 can be sufficiently ensured.

  In this case, the end of each arm part 32, 33 is used by using a fastening member (bolt 22a and nut 22b or bolt 26a and nut 26a) for connecting the connection parts 16 and 17 of the suspension lower arm 15 and the brackets 20 and 25. By adopting a configuration in which the portion is integrally fastened with the connecting portions 16 and 17, an increase in the number of parts when stiffening with the front underframe 30 can be effectively suppressed.

  Here, for example, as shown in FIG. 8, the bracket 41 may be connected to the rear connecting portion 17 on the lower surface side of the support plate 27. With this configuration, it is possible to improve the assembling workability particularly when the front underframe 30 is retrofitted with an option or the like.

  At that time, for example, as shown in FIG. 9, the bracket 41 can be integrated with the support plate 27. By comprising in this way, the increase in the number of parts at the time of stiffening the attachment rigidity of the suspension lower arm 15 with the front under frame 30 can be suppressed effectively.

  Further, for example, as shown in FIG. 10, when the attachment rigidity of the suspension lower arm 15 is sufficiently improved by the front underframe 30, the support plate 27 can be omitted.

  Further, for example, in the configuration shown in FIG. 8 or 10, the bolt insertion hole 41 b that opens in the bracket 41 can be configured as a long hole that includes a release portion 41 c in front of the vehicle body 1 (FIG. 13 ( a), see (b)). With this configuration, at the time of a vehicle collision, the front under frame 30 can be easily detached from the vehicle body 1, and the suspension lower arm 15 can be removed without sacrificing the crushable zone set at the front of the vehicle body 1. Mounting rigidity can be stiffened.

  In order to improve the strength of the bracket 36 itself, ribs 36b may be formed on the edge of the support plate 36a as shown in FIGS. 11A and 11B, for example. ), (B), a bead 36c may be formed on the support plate 36a.

Bottom view showing the main part of the front skeleton structure of the car body Front view showing the main part of the front skeleton structure of the vehicle body Left side view showing the main part of the front skeleton structure of the car body Front underframe perspective view Explanatory drawing showing simulation results of load transmission path Sectional drawing of the principal part which follows the II line | wire of FIG. Fig. 1 is a cross-sectional view of an essential part taken along line II-II in Fig. Sectional drawing of the principal part showing a modification of FIG. Sectional drawing of the principal part showing a modification of FIG. Sectional drawing of the principal part showing a modification of FIG. Explanatory drawing which shows the reinforcement structure of the bracket connected with the front connection part of a suspension lower arm Explanatory drawing which shows the reinforcement structure of the bracket connected with the front connection part of a suspension lower arm Explanatory drawing which shows the structure of the bracket connected with the rear connection part of a suspension lower arm

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Car body 6 ... Side frame 7 ... Suspension cross member 9 ... Exhaust pipe (vehicle body structure)
DESCRIPTION OF SYMBOLS 15 ... Suspension lower arm 16 ... Front connection part 17 ... Rear connection part 22a ... Bolt (fastening member)
22b Nut (fastening member)
26a ... Bolt (fastening member)
26b ... Nut (fastening member)
30 ... Front underframe 31 ... Fixed part 32 ... Front arm part 33 ... Rear arm part
Agent Patent Attorney Susumu Ito

Claims (3)

A fixed portion that is installed between the left and right side frames extending in the front-rear direction, and fixed to the center of the suspension cross member that supports the left and right suspension lower arms extending in the front-rear direction;
A pair of left and right front arm portions that extend in the vehicle width direction starting from the vicinity of the fixed portion and respectively connect the front connecting portion of the suspension lower arm together with the suspension cross member at the end portion;
A vehicular front underframe comprising a pair of left and right rear arm portions extending obliquely rearward from the vicinity of the fixed portion and connecting the rear connecting portions of the suspension lower arm at the ends.   2. The vehicle front underframe according to claim 1, wherein each of the arms has a relief shape with respect to a vehicle body structure disposed below the suspension cross member. Using a fastening member that connects the front connecting portion of the suspension lower arm to the suspension cross member, the end of the front arm portion is fastened integrally with the front connecting portion,
The end part of the said lower arm part was fastened integrally with the said rear connection part using the fastening member which connects the rear connection part of the said suspension lower arm to a vehicle body, The Claim 1 or Claim 2 characterized by the above-mentioned. Front underframe for vehicles.

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