JP2009196613A - Front sub frame of automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a front sub frame of an automobile in which excess torsion and deformation are suppressed to improve traveling stability of a vehicle. <P>SOLUTION: The front sub frame 1 is provided with a front cross member 2 extending in a vehicle width direction, a left and right pair of side members 3 extending from both ends of the front cross member 2 in the vehicle width direction toward a rear of the vehicle, and a rear cross member 4 with first connection parts 41 on both ends to be respectively connected with a rear end of each side member 3. The rear end of the left and right pair of the side members 3 is respectively connected with the first connection parts 41 on both ends of the rear cross member 4 and second connection parts 51 on both ends of a reinforcing member 5 arranged in a vicinity of the rear cross member 3 in parallel to extend in the vehicle width direction that form a double structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a front subframe of an automobile, and more particularly, to a front subframe of an automobile that improves the running stability of the vehicle.

  FIG. 11 shows an example of a front subframe 100 of an automobile. This front subframe 100 is described in, for example, Patent Document 1.

  The front subframe 100 supports a relay rod in a steering device having a pitman arm, supports a rack housing in a rack and pinion type steering device, and rotates a base end portion of a front suspension arm. Connected freely.

  The front subframe 100 includes a pair of left and right side members 101, a front cross member 102 that connects the front end portions of the side members 101 to each other, and a rear cross member 103. The front end portion and the rear end of each side member 101 are provided. It is attached to the main frame (not shown) of the vehicle using a total of four attachment holes 104 provided in the section.

  The pair of left and right side members 101 in the front subframe 100 are formed of aluminum or an aluminum alloy, and the front and rear cross members 102 and 103 are formed of an extruded material of aluminum or aluminum alloy, and the front and rear cross members at the time of casting. It is manufactured by casting both ends of 102 and 103 into a pair of left and right side members 101.

JP-A-11-222152

  By the way, the front subframe 100 of the automobile described in Patent Document 1 is set to have rigidity lower than that of the main frame of the vehicle body or the front side frame included in the main frame, so that a frontal collision, a front side collision, etc. The impact energy of the primary collision is absorbed by axial compression, bending deformation, etc., deformation of the main frame or the front side frame included in the main frame, and collision between the vehicle interior structure and the passenger in the vehicle interior (secondary collision) It is designed to be able to exhibit an energy absorption function that relaxes.

  However, in the front subframe 100, which is structurally weaker than the main frame or the main side frame, when the vehicle is cornering, braking, or accelerating, the suspension is not illustrated through a suspension arm of a front suspension device. Excessive torsion and distortion occur when various external forces to be loaded and a steering reaction force when a steering wheel (not shown) is steered are loaded as loads.

  As described above, if excessive twisting or distortion occurs in the front subframe 100 during driving of the automobile, the ground contact of the left and right front tires becomes unstable, and the running stability of the vehicle decreases. For this reason, there is a concern that subtle “deviations” may occur in the behavior of the vehicle and the driving feeling of the driver, adversely affecting proper driving.

  Moreover, in the overhang structure in which the rear end portions of the pair of left and right side members 101 protrude rearward from the rear cross member 103 as in the front subframe 100 of the automobile described in Patent Document 1, the overhang portion The rigidity becomes lower than other parts, which causes excessive twisting and distortion.

  Therefore, as shown in FIG. 12, a front cross member 102 extending in the vehicle width direction, a pair of left and right side members 101 extending from both ends of the front cross member 102 in the vehicle width direction, and each side member 101 And a rear cross member 103 that connects the rear end portions to each other, and a front subframe 100 of an automobile that eliminates an overhang structure in which the rear end portions of the pair of left and right side members 101 protrude greatly rearward from the rear cross member 103. Can be considered.

  However, even in the front subframe 100 shown in FIG. 12, in a structure in which high rigidity is left only to the rear cross member 103, it is a fact that a desired high rigidity is expected at the rear end of each side member 101. It was difficult. Therefore, during vehicle cornering, braking, or acceleration, various external forces applied via the suspension arm of the front suspension device (not shown) and steering reaction force when steering a steering wheel (not shown) are performed. Excessive torsion and distortion occur due to the load.

  That is, in the conventional front subframe 100 shown in FIGS. 11 and 12, various external forces applied through the suspension arm and steering reaction during steering wheel steering during cornering, braking, or acceleration of the vehicle. Due to the force and the like, excessive torsion and distortion occur, the ground contact of the left and right front tires becomes unstable, and the running stability of the vehicle is lowered.

  The present invention solves such a problem, and an object of the present invention is to provide a front subframe of an automobile that suppresses excessive twisting and distortion and improves running stability of the vehicle. It is in.

In order to achieve the above object, a front subframe of an automobile according to the present invention supports a relay rod or a rack housing of a steering device, a base end portion of a front suspension arm is rotatably connected, and a plurality of A front cross member that extends in the vehicle width direction, a pair of left and right side members that extend from the both ends of the front cross member in the vehicle width direction, and each side member. In a front subframe of an automobile provided with a rear cross member that connects rear end portions of the rear end portions to each other by first connecting portions at both ends,
The rear end portions of the pair of left and right side members are a first connection portion at both ends of the rear cross member and a second connection of both ends of the reinforcing member extending in the vehicle width direction disposed in close proximity to and parallel to the rear cross member. It is characterized by being connected to each other in a double structure with the part.

  As described above, the rear end portions of the pair of left and right side members are connected to the first connecting portions at both ends of the rear cross member and the both ends of the reinforcing members extending in the vehicle width direction disposed in parallel to the rear cross member. By being connected to each other in a double structure with the second connecting portion, the rear end portion of each side member is reinforced by both the rear cross member and the reinforcing member. Thereby, the rigidity of each side member rear end part which has been insufficient with the reinforcement entrusted only to the rear cross member can be compensated and greatly improved. As a result, the rigidity of the entire front subframe against torsion and distortion is enhanced, and various external forces are applied to the front subframe as loads through the suspension arm during vehicle cornering, braking or acceleration, and steering. Even if a steering reaction force during wheel steering is applied to the front subframe as a load, excessive torsion and distortion of the front subframe are suppressed. Therefore, the grounding stability of the left and right front tires can be increased, and the running stability of the vehicle can be improved.

  In the front subframe of the automobile according to the present invention, the reinforcing member includes a main body portion extending in the vehicle width direction and a pair of left and right second connecting portions fixed to both end portions of the main body portion. The portion is fixed to the front surface of the main body portion and extends to the front of the vehicle, the connection plate and a base portion fixed to both end surfaces in the vehicle width direction of the main body portion, and the base portion extending upward from the base portion in the vehicle width direction. A connecting tool having a mounting portion extending outward, and a plurality of the connecting plates are interposed between the lower surface of the rear end of each side member and the upper surface of each first connecting portion of the rear cross member. It is characterized in that it is fastened to the rear end of each side member by a bolt and nut, and the attachment part of each connector is fastened to the main frame of the vehicle by a main frame attachment bolt.

  According to this, the connection plate in each 2nd connection part of a reinforcement member is interposed between the lower surface of the rear-end part of each side member, and the upper surface of each 1st connection part of a rear cross member by several bolts and nuts. By being fastened to the rear end of each side member, the rear end of each side member is connected to each other with a robust double structure, so that the rigidity of the rear end of each side member is reliably increased. Can do.

  In addition, the connecting portion of each connector is fastened to the main frame of the vehicle with higher rigidity than the front subframe by bolts, so that the reinforcing force of the reinforcing member is further increased, and the front subframe is twisted or distorted. The rigidity against can be further increased.

  The main body portion of the reinforcing member in the front subframe of the automobile according to the present invention is made of a high-rigidity hollow steel material, and each of the connection plates and the connection tools is made of a high-rigidity steel plate.

  Thus, in the main body part constituting the reinforcing member, each connecting plate and each connecting tool, the main body part having the largest occupied volume is made of high-rigidity hollow steel material, so that the reinforcing member has high rigidity. However, the weight can be reduced and the weight of the vehicle body can be reduced. In addition, each connecting plate and each connecting tool is made of a high-rigidity steel plate, thereby increasing the connection strength to each other member such as the rear end of each side member and the main frame of the vehicle, and the rear end of each side member by the reinforcing member. This can contribute to improving the rigidity of the part.

  ADVANTAGE OF THE INVENTION According to this invention, the excessive twist and distortion of the front sub-frame of a motor vehicle can be suppressed, and the running stability of a vehicle can be improved.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of an embodiment in which a rear cross member and a reinforcing member of an automobile front subframe according to the present invention are disassembled, as viewed from the front side, and FIG. 2 is an enlarged bottom view of a left end portion of the rear cross member. FIG. 3 is an enlarged bottom view of the left end portion of the reinforcing member, and FIG. 4 is a view taken along arrow VI-VI in FIG. The arrows “front and rear”, “left”, “right”, “upper”, and “lower” shown in FIGS. 1 to 4 indicate directions viewed from the driver, and each figure will be described according to this direction.

  1 to 4, a front subframe 1 of an automobile includes a front cross member 2 extending in the vehicle width direction and a pair of left and right side members 3 extending from the both ends of the front cross member 2 in the vehicle width direction to the rear of the vehicle. And a rear cross member 4 for connecting the rear end portions of the side members 3 to each other, and a reinforcing member 5 extending in the vehicle width direction.

  The front subframe 1 supports a relay rod when the steering device (not shown) includes a pitman arm, and supports a rack housing when the rack and pinion type is used, and a base end of a front suspension arm (not shown). The main frame mounting bolts 7a, 7b, and 7c are inserted from below into a plurality of bolt insertion holes (plural mounting portions) 6a, 6b, and 6c provided in the side members 3 so that the portions are rotatably connected. The front sub-frame 1 is attached to the lower side of the floor surface of the main frame of the vehicle by screwing these tip portions into screw holes provided in the main frame of the vehicle described later.

  The rear cross member 4 is composed of a main body portion 40 extending in the vehicle width direction and a pair of left and right first connecting portions 41 fixed to both ends of the main body portion 40 by welding. As shown in FIG. 2, each first connecting portion 41 is made of a stainless steel pipe (however, since the pair of first connecting portions 41 are symmetrical, the left first connecting portion 41 is shown in FIG. The first connecting portion 41 on the right side is not shown), and is formed of a substantially L-shaped steel plate or stainless steel plate that is pressed into a downward shape, and is bent obliquely downward at the outer peripheral edge thereof. Reinforcing ribs 41a are formed, the first bolt insertion hole 41b is slightly rearward at a position close to the main body 40, and the second bolt insertion hole is at a position spaced from the main body 40 outward in the vehicle width direction. 41c penetrates each Together are made, the third bolt insertion hole 41d is formed through at a position spaced forwardly from the second bolt insertion holes 41c.

  The reinforcing member 5 includes a main body portion 50 extending in the vehicle width direction, and a pair of left and right second connecting portions 51 fixed to both ends of the main body portion 50 by welding. The main body portion 50 is a steel pipe or stainless steel having a square cross section. As shown in FIG. 3, each second connecting portion 51 is made of a steel pipe (however, since the pair of second connecting portions 51 is symmetrical, the left second connecting portion 51 is shown in FIG. The right-side second connecting portion 51 is not shown), a substantially chevron-shaped connecting plate 52 that is fixed to the front surface 50a of the main body portion 50a by welding and extends forward of the vehicle, the connecting plate 52, and the main body portion. 50, both ends of the vehicle in the vehicle width direction are fixed to each other by welding, and the connection plate 52 is made of a pressed flat steel plate or stainless steel plate. Welded to 50 vehicle width direction end faces Therefore, it has a base 53a that is fixed and extends upward, and a mounting portion 53b that extends outward from the base 53a in the vehicle width direction, and is constituted by a steel plate or a stainless steel plate that is press-processed or combined with press and welding. Has been.

  Corresponding to the first bolt insertion hole 41b of the first connection part 41 shown in FIG. 2, a first bolt insertion hole 52a is formed through the connection plate 52 of the second connection part 51 as shown in FIG. In addition, corresponding to the second bolt insertion hole 41c of the first connecting portion 41 shown in FIG. 2, a second bolt insertion hole 52b is formed through the connecting plate 52 of the second connecting portion 51 as shown in FIG. A third bolt insertion hole 53c is formed through the attachment portion 53b of the connector 53. As shown in FIGS. 1, 3, 4, and 5, each connecting plate 51 has a tapered shape in which the inner diameter is gradually reduced from the lower side to the upper side by a combined process of shearing and bending by pressing. A large-diameter hole 52c is provided. By providing such a tapered and large-diameter hole 52c, each connecting plate 51 can be reduced in weight without reducing its rigidity. As a result, the reinforcing member 5 is reduced in weight while maintaining a predetermined rigidity, thereby contributing to a reduction in the weight of the vehicle body.

  Next, a procedure for connecting the rear cross member 4 and the reinforcing member 5 to the rear end portion of each side member 3 in the front subframe 1 will be described.

  First, as shown in FIG. 5, a pair of left and right first connecting portions 41 of the rear cross member 4 (however, the left first connecting portion 41 is shown in FIG. 5 and the right first connecting portion 41 is not shown). A pair of left and right second connecting portions 51 of the reinforcing member 5 (note that the left second connecting portion 51 is shown in FIG. 5 and the right second connecting portion 51 is not shown). The main body part 50 of the reinforcing member 5 is brought close to and parallel to the rear side of the main body part 40 of the rear cross member 4, and the first bolt insertion hole 41b of the first connection part 41 and the second connection part are overlapped. The first bolt insertion hole 52 a of the part 51 is communicated, and the second bolt insertion hole 41 c of the first connection part 41 and the second bolt insertion hole 52 b of the second connection part 51 are communicated. Further, the connecting tool 53 of the second connecting portion 51 is exposed to the outside in the vehicle width direction than the first connecting portion 41.

  As shown in FIG. 6, each side member 3 has a bottom bolt 8 joined in advance as a welding bolt on the lower surface thereof by, for example, upset welding, and this bottom bolt 8 is connected to the second connecting portion 51. The first bolt insertion hole 52 a and the first bolt insertion hole 41 b of the first connection portion 41 are inserted, and nuts 9 are screwed to the front end portions of the first bolt insertion holes 52 a and the second connection portions 51 and the first connection to the side members 3. The part 41 is fastened.

  Moreover, as shown in FIG. 7, the bolt insertion which provided the 2nd bolt insertion hole 41c of the 1st connection part 41 and the 2nd bolt insertion hole 52b of the connection board 52 in the 2nd connection part 51 in each side member 3. As shown in FIG. 6e is connected to the lower side, and the fastening bolt 10 is inserted into the connected bolt insertion holes 41c, 52b, and 6e from the lower side, and the tip portion thereof is slightly exposed above each side member 3, and the nut 11 is provided here. The second connecting portion 51 and the first connecting portion 41 are fastened to each side member 3 by screwing, and a thickness equal to the thickness of the connecting plate 52 in the second connecting portion 51 is formed on the upper surface of the first connecting portion 41. The washer 12 that functions as a spacer is placed, the center hole 12a is communicated with the third bolt insertion hole 41d of the first connecting portion 41, and the center hole 12a and the third bolt insertion hole 41d of the washer 12 are further provided. Each side The bolts 6f provided on the lumbar 3 communicate with each other under the bolt insertion holes 6f. The fastening bolts 13 are inserted into the bolt insertion holes 41d, the center holes 12a, and the bolt insertion holes 6f from the lower side, and the tip portions of the side members 3 are connected. The nut 11 is screwed here, and the washer 12 and the first connecting portion 41 are fastened to each side member 3.

  Further, as shown in FIG. 8, the third bolt insertion hole 53 c formed in the attachment portion 53 b of the connector 53 in the second connection portion 51 is communicated with the lower side of the bolt insertion 6 c provided in each side member 3. The main frame mounting bolt 7c is inserted from below into the connected bolt insertion holes 53c, 6c, and the male screw portion at the tip thereof is screwed into the screw hole 15c provided in the main frame 15 of the vehicle to connect the connector 53 to the vehicle. The main frame 15 is fastened. As a result, as shown in FIG. 9, the rear end portions of the pair of left and right side members 3 in the front subframe 1 are disposed in parallel with both ends of the rear cross member 4 in the vehicle width direction and in close proximity to the rear cross member 4. The reinforcing members 5 extending in the vehicle width direction are connected to each other in a double structure with both ends in the vehicle width direction.

  As shown in FIGS. 1 and 10, the bolt insertion holes 6 a provided in each side member 3 communicate with each other below the screw holes 15 a provided in the main frame 15 of the vehicle, and are provided in each side member 3. The bolt insertion hole 6b is communicated with the lower side of the screw hole 15b provided in the main frame 15 of the vehicle, and the main frame mounting bolt 7a is inserted into the communicated bolt insertion hole 6a and the screw hole 15a from the lower side. Is screwed into the screw hole 15a, and the main frame mounting bolt 7b is inserted into the communicating bolt insertion hole 6b and screw hole 15b from the lower side, and the male screw part at the tip is screwed into the screw hole 15b. Thus, the front sub-frame 1 is attached to the lower side of the floor surface of the main frame 15 of the vehicle.

  As described above, the rear end portions of the pair of left and right side members 3 in the front subframe 1 are close to and parallel to the first connecting portions 41 at both ends in the vehicle width direction of the rear cross member 4 and the rear cross member 4. Reinforced members 5 that extend in the vehicle width direction are connected to each other in a double structure with the second connection portions 51 at both ends in the vehicle width direction, so that the rear end portions of the side members 3 are rear cross members. 4 and the reinforcing member 5 are reinforced. Therefore, the rigidity of the rear end portion of each side member 3 that is insufficient with the reinforcement only by the rear cross member 4 can be compensated and greatly improved. As a result, the rigidity of the entire front subframe 1 against torsion and distortion is enhanced, and various external forces are applied as loads to the front subframe 1 through suspension arms (not shown) during cornering, braking or acceleration of the vehicle. Even when a steering reaction force or the like during steering of a steering wheel (not shown) is applied to the front subframe 1 as a load, excessive twisting or distortion of the front subframe 1 is suppressed. Therefore, the ground contact stability of the left and right front tires can be increased, and the running stability of the vehicle can be improved.

  Further, a plurality of connecting plates 52 in each second connecting portion 51 of the reinforcing member 5 are interposed between the lower surface of the rear end portion of each side member 3 and the upper surface of each first connecting portion 41 of the rear cross member 4. By being fastened to the rear end of each side member 3 with bolts, nuts 10, 11, 13, and 14, the rear end of each side member 3 is connected to each other in a robust double structure. The rigidity of the rear end portion of each side member 3 can be reliably increased.

  Further, the attachment portion 53b of each connector 53 in each second connection portion 51 is screwed and fastened to the screw hole 15c of the main frame 15 of the vehicle having higher rigidity than the front subframe 1 by the main frame attachment bolt 7c. As a result, the reinforcing force of the reinforcing member 5 is further increased, and the rigidity of the front subframe 1 against twisting and distortion can be further increased.

  Further, in the main body 50 constituting the reinforcing member 5, each connecting plate 52 and each connecting tool 53, the main body 50 having the largest occupied volume is configured by a high-rigidity hollow steel material made of a steel pipe or a stainless steel pipe having a square cross section. Thus, the reinforcing member 5 can achieve weight reduction and contribute to reduction of the vehicle body weight while having high rigidity. Each connecting plate 52 is made of a press-processed flat steel plate or a high-rigidity steel plate made of stainless steel plate, and each connecting tool 53 is made of a press-processed or combined steel plate or stainless steel plate made of press and welding. By being constituted by the high-rigidity steel plate, the connection strength to the other members such as the rear end portions of the side members 3 and the main frame 15 of the vehicle is increased, and the rear end portions of the side members 3 by the reinforcing members 5 are increased. It can contribute to the improvement of rigidity.

It is the perspective view which looked at one Embodiment which decomposed | disassembled the rear part cross member and reinforcement member of the front sub-frame of the motor vehicle based on this invention from the front side. It is an enlarged bottom view of the left end part of a rear cross member. It is an enlarged bottom view of the left end part of a reinforcement member. It is a VI-VI arrow line view of FIG. It is an enlarged bottom view of the state which piled up the left end part of the reinforcement member on the upper side of the left end part of a rear cross member. It is an expanded vertical sectional view of the state which fastened the 1st connecting part and the 2nd connecting part to the side member using the 1st bolt penetration hole. The first connecting part and the second connecting part are fastened to the side member using the second bolt insertion hole, and the first connecting part is fastened to the side member using the third bolt insertion hole and the washer. It is an enlarged vertical sectional view. It is an expanded longitudinal cross-sectional view of the state which fastened the connector in the 2nd connection part to the main frame. It is the perspective view which looked at one Embodiment of the assembly state of the front sub-frame of the car concerning the present invention from the front side. It is an enlarged vertical sectional view of a state where the front subframe is bolted to the main frame. It is a perspective view of the 1st prior art example. It is a perspective view of the 2nd conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front sub-frame 2 Front part cross member 3 Left-right paired side member 4 Rear part cross member 41 1st connection part 5 Reinforcement member 50 Main body part 51 2nd connection part 52 Connection plate 53 Connection tool 53a Base part 53b of connection tool Mounting part 6a-6c Bolt insertion hole (plural mounting parts)
7a to 7c Main frame mounting bolts 8 Snail bolts (welding bolts for fastening)
9 Nut 10 Fastening bolt 11 Nut 12 Washer 13 Fastening bolt 14 Nut 15 Vehicle main frame

Claims (3)

Before supporting the relay rod or rack housing of the steering device, the base end of the front suspension arm is pivotably connected, and is attached to the main frame of the vehicle by a plurality of attachments, and before extending in the vehicle width direction A cross member, a pair of left and right side members extending from the both ends in the vehicle width direction of the front cross member to the rear of the vehicle, and a rear cross member that connects the rear end portions of the side members to each other at the first connecting portions at both ends. In the front subframe of a car equipped with
The rear end portions of the pair of left and right side members are a first connection portion at both ends of the rear cross member and a second connection of both ends of the reinforcing member extending in the vehicle width direction disposed in close proximity to and parallel to the rear cross member. A front subframe of an automobile characterized by being connected to each other in a double structure with a part. In the front sub-frame of the automobile according to claim 1,
The reinforcing member includes a main body portion extending in the vehicle width direction and a pair of left and right second connecting portions fixed to both ends of the main body portion, and the second connecting portion is fixed to the front surface of the main body portion. A connecting tool having a connecting plate extending forward of the vehicle, a base portion fixed to both end surfaces in the vehicle width direction of the connecting plate and the main body portion, and an attaching portion extending outward in the vehicle width direction from the base portion. And each connecting plate is interposed between the lower surface of the rear end portion of each side member and the upper surface of each first connecting portion of the rear cross member, and the rear end of each side member by a plurality of bolts and nuts. A front sub-frame of an automobile, wherein the front sub-frame of the automobile is fastened to a main part of the vehicle by a main frame mounting bolt. In the front subframe of the automobile according to claim 2,
The body part of the reinforcing member is made of a high-rigidity hollow steel material, and each of the connection plates and the connection tools is made of a high-rigidity steel plate.

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