JP5230551B2 - Front subframe structure for vehicles - Google Patents

Description

  The present invention relates to a vehicle front subframe structure in which a steering gear box is supported on a front edge portion of a front subframe attached to a front lower surface of a vehicle body, and suspension arms are supported on both left and right side portions of the front subframe.

  Japanese Patent Application Laid-Open Publication No. 2004-228667 discloses a front subframe (front suspension member) made of aluminum die cast in which a front suspension device and a steering gear box are assembled in advance as a subassembly.

Japanese Patent No. 4206840

  By the way, the rack and pinion type steering gear box includes a gear box body that supports the rack bar so as to be slidable in the left and right directions, and a steering torque sensor that protrudes obliquely rearward and upward from one end side in the left and right direction of the gear box body toward the vehicle interior The pinion shaft connected to the pinion meshing with the rack bar is supported by the steering torque sensor. When the gear box body of the steering gear box is fixed along the front edge of the front subframe, the front subframe has a lower surface so that the steering torque sensor can be disposed without interfering with the front edge of the front subframe. An inverted U-shaped opening is formed.

  However, since the suspension arm of the front suspension device is supported in the vicinity of the opening of the front subframe, the front subframe whose rigidity has been reduced by the opening may be deformed by a load input from the suspension arm.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to increase the rigidity of a front sub-frame in which an opening for accommodating a steering torque sensor of a steering gear box is formed.

  In order to achieve the above object, according to the first aspect of the present invention, the steering gear box is supported on the front edge portion of the front subframe attached to the lower surface of the front portion of the vehicle body, and the left and right sides of the front subframe are supported. A vehicle front sub-frame structure that supports suspension arms on both sides, wherein a partially open opening for accommodating a steering torque sensor of the steering gear box is formed on the left and right ends of the front edge, A vehicular front subframe structure is proposed in which an opening portion of the opening is closed by a connecting portion connected to a support portion of the suspension arm.

  According to a second aspect of the present invention, in addition to the structure of the first aspect, the connecting portion is die-cast integrally with the front subframe, and the opening of the front subframe and the support of the suspension arm are formed. The vehicle front sub-frame structure is proposed in which the portions are arranged at substantially the same height, and the connecting portion includes an arc-shaped reinforcing rib at a portion facing the opening.

  The front cross member 13 of the embodiment corresponds to the front edge portion of the present invention, the side member 15 of the embodiment corresponds to the side portion of the present invention, and the mounting bracket 15b of the embodiment of the present invention. Corresponding to the support portion, the lower arm 22 of the embodiment corresponds to the suspension arm of the present invention, and the lower opening 29 of the embodiment corresponds to the opening of the present invention.

  According to the configuration of the first aspect, the steering gear box is supported on the front edge portion of the front subframe, and the suspension arms are supported on the left and right side portions of the front subframe. If the steering torque sensor of the steering gear box is housed in a partially open opening formed at the front edge of the front subframe, the rigidity of the front subframe is lowered by the opening, and there is a risk of deformation when a large load is input from the suspension arm. However, since the opening part of the opening is closed by the connecting part connected to the support part of the suspension arm, it is possible to increase the rigidity of the front subframe near the opening and prevent deformation without increasing the number of parts or weight. it can.

  According to the second aspect of the present invention, since the connecting portion is integrally die-cast with the front subframe, the number of parts can be reduced as compared with the case where the connecting portion is formed of a separate member and coupled to the front subframe. Can do. In addition, since the opening of the front subframe and the support part of the suspension arm are arranged at substantially the same height, the load input to the support part of the suspension arm can be distributed and transmitted to the main body part and the connecting part of the front subframe. In addition, since the arc-shaped reinforcing rib is provided at the portion where the connecting portion faces the opening, the breaking strength of the connecting portion can be increased.

The perspective view which looked at the front sub-frame from diagonally downward. FIG. 2 is a view in the direction of the arrow 2 in FIG. 1 (a bottom view of the front subframe). FIG. 3 is a view in the direction of arrows 3 in FIG. 1 (front view of the front subframe). FIG. 4 is an enlarged view of part 4 of FIG. 2.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 to 4, a front sub-frame 12 is detachably supported on the lower surfaces of a pair of left and right front side frames 11, 11 arranged in the front-rear direction on the left and right sides of the front part of a vehicle body. The front sub-frame 12 is a square frame-shaped member, and includes a front cross member 13 extending in the vehicle width direction, a rear cross member 14 extending in the vehicle width direction behind the front cross member 13, and a front cross member 13. And a pair of left and right side members 15 extending in the front-rear direction on the outer side in the vehicle width direction of the rear cross member 14. The front sub-frame 12 is fastened to the front side frames 11 and 11 by bolts at vehicle body attachment portions 15a provided at four locations, the front portions of the left and right side members 15 and 15 and the middle portion in the front-rear direction.

  In addition to an engine (not shown) and a transmission (not shown), a rack and pinion type steering gear box 16 is fixed to the front subframe 12 with two bolts 31 and 31 on the front surface of the front cross member 13. At the same time, front suspension devices 17 and 17 are supported on both the left and right sides. The steering gear box 16 includes a gear box main body 16a in which a rack bar is slidably supported left and right, a steering torque sensor 16b that protrudes obliquely rearward and upward from the left end (in the case of a left-hand drive vehicle) of the gear box main body 16a, Tie rods 19 and 19 are provided that extend left and right from a rack bar housed in the gear box body 16a and steer the left and right front wheels 18 and 18, respectively. The steering torque sensor 16b accommodates a pinion shaft 16c extending from a pinion meshing with the rack bar, and the pinion shaft 16c is connected to a steering shaft 20 extending toward the vehicle compartment via a cardan joint 21.

  Each front suspension device 17 is of a double wishbone type and includes an A-type lower arm 22 and an A-type upper arm (not shown). The front end of the lower arm 22 is pivotally supported via a rubber bush joint 32 between mounting brackets 15b and 15c formed on the front of the side member 15, and the rear rear side of the lower arm 22 Is pivotally supported on the rear part of the side member 15 via a rubber bush joint 33. The tip of the lower arm 22, the tip of an upper arm (not shown) supported on the side of the front sub-frame 12 on the base end side, and the tip of the tie rod 19 are connected to the knuckle 26 of the front wheel 18 via a ball joint. Pivoted. The end of the stabilizer 27 is connected to the knuckle 26 via a link (not shown) arranged in the vertical direction.

  An upper opening 28 penetrates the side member 15 of the front subframe 12 in the vertical direction, and a lower opening 29 penetrates the connection portion between the front cross member 13 and the side member 15 of the front subframe 12 in the substantially front-rear direction. Since the front subframe 12 made of aluminum die casting is a flat member extending generally in a horizontal plane, the mold for molding the front subframe 12 is divided into upper and lower parts (see the mold dividing line in FIG. 3). Therefore, the upper opening 28 can be formed only by the upper mold and the lower mold without using the core, while the lower opening 29 is formed by using the core that slides in the front-rear direction with respect to the mold.

  The lower opening 29 originally has a shape that is partially opened for the convenience of die splitting when the front subframe 12 is die-cast, but in this embodiment, the opening is a plate that is continuous in an L shape. It is covered with the connection parts 30A and 30B and has a closed cross section. That is, the connecting portion 30 </ b> A extending in the horizontal direction is connected to the front mounting bracket 15 a that extends outward in the left-right direction and supports the front end side front portion of the lower arm 22. Further, the connecting portion 30A extends upward from the outer end in the left-right direction and is interposed between the lower opening 29 and the mounting bracket 15a.

  As clearly shown in FIG. 3, the center of the lower opening 29 and the position at which the front end of the base end side of the lower arm 22 is pivotally supported by the mounting bracket 15b (see bolt hole 15d) in the front view are substantially the same height. . Further, plate-like reinforcing ribs 29a are formed in an arc shape on the portion where the connecting portions 30A and 30B face the lower opening 29, specifically on the lower surface of the lower opening 29 and the outer surface in the vehicle width direction.

  The front subframe 12 is formed with an upper opening 28 'and a lower opening 29' which are not used separately from the upper opening 28 and the lower opening 29 and are symmetrically formed. 12 is used for both a left-hand drive vehicle and a right-hand drive vehicle.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  When the steering gear box 16 is fixed to the front cross member 13 of the front sub-frame 12, a steering torque sensor 16 b that protrudes rearward and upward from the gear box main body 16 a of the steering gear box 16 is provided in the lower opening 29 of the front sub-frame 12. Stored inside. The pinion shaft 16c protruding rearward and upward from the steering torque sensor 16b passes through the lower opening 29, and the steering shaft 20 connected to the upper end of the pinion shaft 16c via the cardan joint 21 moves the upper opening 28 of the side member 15 upward from below. It penetrates and extends into the passenger compartment.

  Part of the load that the front wheel 18 receives from the road surface is transmitted to the side member 15 of the front subframe 12 via the knuckle 26, the lower arm 22 and the bifurcated mounting brackets 15b and 15c of the side member 15, and from there to the front Is transmitted to the cross member 13. At this time, assuming that a lower opening 29 that is partially opened is formed in the connection portion between the side member 15 and the front cross member 13, the rigidity of the front sub-frame 12 is lowered by the lower opening 29 and is easily deformed. There is a problem. However, according to the present embodiment, the open portion of the lower opening 29 is covered with the connecting portions 30A and 30B, so that the lower opening 29 has a closed cross-sectional structure having no open portion, and the connecting portions 30A and 30B are lower arms. 22 is connected to one of the two mounting brackets 15b and 15c, the rigidity in the vicinity of the lower opening 29 is increased, and the deformation of the front sub-frame 12 with respect to the load input from the lower arm 22 is effective. Can be prevented.

  Further, since the center of the lower opening 29 and the position where the base end side front portion of the lower arm 22 is pivotally supported by the mounting bracket 15b (see the bolt hole 15d in FIG. 3) are substantially at the same height, they are input to the mounting bracket 15b. The load is distributed substantially evenly between the upper path of the lower opening 29 (path that does not pass through the connecting portions 30A and 30B) and the lower path of the lower opening 29 (path that passes through the connecting portions 30A and 30B). It can be transmitted to the cross member 13 and part of the load can be shared by the connecting portions 30A and 30B, so that the deformation of the front subframe 12 can be more effectively suppressed. In addition, since the arc-shaped reinforcing ribs 29a are provided in the connecting portions 30A and 30B facing the lower opening 29, the rigidity around the lower opening 29 can be further increased by the reinforcing ribs 29a.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, the connecting portions 30A and 30B are formed integrally with the front subframe 12, but the connecting portions 30A and 30B are formed as separate members from the front subframe 12 and welded or bolted to the front subframe 12. You may combine by fastening.

  In the embodiment, the front subframe 12 is made of aluminum die cast, but may be made of sheet metal press.

12 Front sub-frame 13 Front cross member (front edge)
15 Side member (side)
15b Mounting bracket (support)
16 Steering gear box 16b Steering torque sensor 22 Lower arm (suspension arm)
29 Lower opening (opening)
29a Reinforcing rib 30A connecting part 30B connecting part

Claims (2)

A steering gear box (16) is supported on a front edge portion (13) of a front subframe (12) attached to the lower surface of the front portion of the vehicle body, and suspension arms are provided on both left and right side portions (15) of the front subframe (12). (22) a vehicle front subframe structure for supporting,
A partially open opening (29) for accommodating the steering torque sensor (16b) of the steering gear box (16) is formed on the left and right ends of the front edge (13), and the opening (29) is opened. The vehicle front subframe structure is characterized in that the portion is closed by a connecting portion (30A, 30B) connected to the support portion (15b) of the suspension arm (22).   The connecting portions (30A, 30B) are die-cast integrally with the front subframe (12), and the opening (29) of the front subframe (12) and the support portion (15b) of the suspension arm (22) are formed. 2. The vehicle according to claim 1, wherein the connecting portions (30 </ b> A, 30 </ b> B) are arranged at substantially the same height, and are provided with arc-shaped reinforcing ribs (29 a) in a portion facing the opening (29). Front subframe structure.

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