JP6052605B2 - Body front structure - Google Patents

Description

  The present disclosure relates to a vehicle body front portion structure including a pair of subframes that connect a vehicle body front end portion and a suspension cross member in a vehicle front-rear direction.

Conventionally, a method for suppressing vibration generated in a vehicle by providing a dynamic damper that resonates with the vibration of the vehicle is known.
For example, Patent Document 1 discloses a high-pressure tank support structure in which a high-pressure tank filled with gaseous fuel of a fuel cell vehicle is configured as a dynamic damper mass.
Patent Document 2 discloses a lower-floor component support structure in which a cross member for supporting lower-floor components such as a transmission is configured as a mass body of a dynamic damper.

Japanese Patent No. 4857306 Japanese Patent No. 4720304

  However, Patent Document 1 described above is configured by using a high-pressure tank filled with a gaseous fuel such as hydrogen as a mass body of a dynamic damper, and cannot be applied to a vehicle that does not include the high-pressure tank. Also in Patent Document 2 described above, when forming a space for storing a part under the floor by raising a part of the floor of the vehicle body, a support member (cross member) for supporting the part under the floor stored therein Is configured as a mass body of a dynamic damper, and cannot be applied to a vehicle that does not include such a lower-floor component support structure.

  At least one embodiment of the present invention has been made in view of the above-described problems, and the object thereof is a simple configuration using existing parts without using a new heavy article, An object of the present invention is to provide a vehicle body front structure that can effectively suppress vibration transmitted from a suspension cross member to a vehicle body.

In order to achieve the above-described object, at least one embodiment of the vehicle body front structure of the present invention is provided.
A front end cross member extending in the vehicle width direction at the front end of the vehicle;
A suspension cross member that is positioned on the vehicle rear side with respect to the front end cross member, extends in the vehicle width direction, and supports a suspension arm member;
A pair of sub-frames extending in the front-rear direction of the vehicle, the front ends of which are respectively connected to the front-end cross members;
A pair of bracket members that respectively connect the rear end portions of the pair of subframes and the suspension cross member;
Each of the pair of bracket members is
Including a flat plate-like connecting portion provided protruding from the suspension cross member;
The connecting portion is connected to one rear end portion of the pair of subframes with a flat plate surface oriented in the vertical direction.

In the vehicle body front structure, a connecting portion connected to the subframe is provided so as to protrude from the suspension cross member, and is connected to the rear end portion of the subframe with its flat plate surface oriented in the vertical direction. For this reason, the bracket member including the connecting portion functions as a spring element that is elastically deformed with the vibration in the vertical direction of the vehicle. That is, the subframe and the bracket member can be configured as a dynamic damper having the subframe as a mass body and the bracket member as a spring element.
Thus, according to the vehicle body front structure, vibration transmitted from the suspension cross member to the vehicle body side can be suppressed by using the existing subframe without using a new heavy object. it can.

Further, in one embodiment of the present invention, each of the pair of bracket members further includes an extension wall portion that protrudes from the suspension cross member in the vehicle width direction, and the flat plate-like connecting portion includes The extension wall portion is provided to extend forward and is fastened to a rear end portion of one of the pair of subframes by a fastening member.
According to such a configuration, the connecting portion can be provided so as to protrude from the suspension cross member with a simple configuration. And since a connection part and the rear-end part of a sub-frame are fastened by a fastening member, it is excellent also in assembly property.

In one embodiment of the present invention, each of the pair of bracket members further includes a vertical wall-shaped side wall part, and a flange part provided to extend from a lower edge part of the side wall part, The side wall portion and the suspension cross member are joined by welding in a state where the flange portion is disposed on the flange portion formed at the front edge portion of the suspension cross member.
According to such a structure, a bracket member and a suspension cross member can be firmly connected by welding in a side wall part. At this time, since the flange portion of the bracket member can be welded in a state of being disposed on the flange portion of the suspension cross member, the welding workability is excellent.

In addition, at least one embodiment of the vehicle body front structure of the present invention,
A front end cross member extending in the vehicle width direction at the front end of the vehicle;
A suspension cross member that is positioned on the vehicle rear side with respect to the front end cross member, extends in the vehicle width direction, and supports a suspension arm member;
A pair of sub-frames extending in the front-rear direction of the vehicle, the front ends of which are respectively connected to the front-end cross members;
A pair of bracket members that respectively connect the rear end portions of the pair of subframes and the suspension cross member;
Each of the pair of bracket members is configured as a spring element that is elastically deformed with vibration in the vertical direction of the vehicle, and each of the pair of subframes is a dynamic damper that suppresses vibration in the vertical direction of the vehicle. It is configured to function as a mass body.

  In the vehicle body structure, the bracket member that connects the suspension cross member and the sub frame is configured as a spring element that is elastically deformed in accordance with vibrations in the vertical direction of the vehicle, so that each of the pair of sub frames can be It is configured to function as a mass body of a dynamic damper that suppresses vibration in the direction. Thereby, the vibration transmitted from the suspension cross member to the vehicle body side can be reduced by using the subframe which is an existing part without using a new heavy object.

In an embodiment of the present invention, the resonance frequency of the dynamic damper composed of the pair of bracket members and the pair of subframes is configured to be equal to the resonance frequency of the suspension cross member.
If comprised in this way, the vibration of 120 Hz vicinity which tends to be a problem generally with road noise can be suppressed.

  According to at least one embodiment of the present invention, the subframe and the bracket member can be configured as a dynamic damper having the subframe as a mass body and the bracket member as a spring element, so that a new heavy object is not used. By using the subframe which is an existing part, vibration transmitted from the suspension cross member to the vehicle body side can be effectively suppressed.

In the vehicle body front part structure according to one embodiment, it is a perspective view of a vehicle body front part viewed from below. 1 is a plan view of a lower structure of a vehicle body front portion viewed from above in a vehicle body front structure according to an embodiment. In the vehicle body front part structure according to one embodiment, it is an enlarged perspective view showing a connecting portion between a rear end portion of a subframe and one end portion of a suspension cross member. It is the perspective view which showed the bracket member concerning one Embodiment. In the vehicle body front part structure concerning other embodiment, it is the perspective view which expanded and showed the connection location of the rear-end part of a sub-frame, and the one end part of a suspension cross member. It is the perspective view which showed the bracket member concerning other embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
However, the scope of the present invention is not limited to the following embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the following embodiments are not merely intended to limit the scope of the present invention, but are merely illustrative examples.

  FIG. 1 is a perspective view of a front part of a vehicle body viewed from below. FIG. 2 is a plan view of the lower structure of the front part of the vehicle body as viewed from above. In FIG. 2, the direction indicated by the arrow X is the front-rear direction of the vehicle, and the direction indicated by the arrow Y is the vehicle width direction (vehicle width direction).

  As shown in FIGS. 1 and 2, the vehicle body front structure 10 includes a front end cross member 14 extending in the vehicle width direction, and a suspension cross member 20 positioned on the vehicle rear side with respect to the front end cross member 14. A pair of left and right subframes 21 and 22 extending in the longitudinal direction of the vehicle and a pair of left and right suspension arm members 35 and 36 supported by the suspension cross member 20 are provided.

  The front end cross member 14 extends in the vehicle width direction below the bumper beam 13 at the front end portion of the vehicle, and both end portions thereof are fixed to the left and right side members 11 and 12 via brackets 23, respectively.

  The sub frames 21 and 22 are long plate-like members extending in the front-rear direction of the vehicle between the front end cross member 14 and the suspension cross member 20. The sub-frames 21 and 22 are fixed to a bracket 23 whose front end portions 21 a and 22 a located in front of the vehicle are connected to the front-end cross member 14. Further, rear end portions 21b and 22b located at the rear of the vehicle are fixed to the suspension cross member 20 via bracket members 55 and 56, respectively. A traction support member 24 for fixing the traction rope when the vehicle is towed is fixed in the vicinity of the connection portion of the bracket 23 with the sub frames 21 and 22.

  The suspension cross member 20 is connected to the side members 11 and 12 of the vehicle body by a pair of support members 30 and 31 extending above the vehicle. In addition, suspension arm members (lower arms) 35 and 36 forming a part of the front suspension are provided at both left and right ends of the suspension cross member 20.

  The suspension cross member 20 includes a cross member main body 20a extending in the vehicle width direction of the vehicle, and a front arm support portion 40 and a rear arm support portion 41 integrally extending at both left and right ends of the cross member main body 20a. Is provided. The front arm support portion 40 extends obliquely outward and forward in the vehicle width direction. The rear arm support portion 41 extends outward and obliquely rearward in the vehicle width direction.

  The sub-frames 21 and 22 described above are connected to both ends of the suspension cross member 20 via bracket members 55 and 56, respectively. The bracket members 55 and 56 are joined to the front arm support portion 40 of the suspension cross member 20 and the bush mounting members 50 and 51 fixed to the front arm support portion 40 by welding, respectively.

  FIG. 3 is an enlarged perspective view showing a connection portion between the rear end portion of the subframe and one end portion of the suspension cross member. FIG. 4 is a perspective view showing the bracket member. In addition, the structure of the connection location of the sub-frames 21 and 22 and the suspension cross member 20 is the same at one end and the other end. For this reason, in the following description, the connection part of the sub-frame 21 and the one end part of the suspension cross member 20 is demonstrated to an example.

  As shown in FIG. 3, a bush mounting member 50 is joined to the front arm support portion 40 of the suspension cross member 20 by welding. Reference numerals W1 and W2 indicate the welding points. The bush mounting member 50 is connected to the suspension arm member 35. The suspension arm member 35 is supported by the bush mounting member 50, the front arm support portion 40, and the rear arm support portion 41 so as to be rotatable in the vertical direction. A knuckle member is provided at each of the distal end portions 35a and 36a of the suspension arm members 35 and 36, and a front wheel 45 shown in FIG. 1 is supported via the knuckle member. As a result, the vertical vibration caused by the road noise is transmitted from the front wheel 45 to the vehicle body via the suspension cross member 20.

  As shown in FIG. 4, the bracket members 55 and 56 include a front wall portion 71 in which a circular opening 90 is formed in the center portion, and a side wall portion 74 that is located on the inner side in the vehicle width direction with respect to the front wall portion 71. The upper wall part 72 positioned on the upper side of the front wall part 71, the extension wall part 73 positioned on the outer side in the vehicle width direction with respect to the front wall part 71, the connecting part 70 positioned in front of the extension wall part 73, etc. Is included.

  The front wall portion 71 is disposed with a gap in front of the bush mounting member 50 fixed to the front arm support portion 40. Between the front wall portion 71 and the bush mounting member 50, the head of the rotating shaft 64 connected to the suspension arm member 35 is located. Then, a rotation tool (not shown) is inserted from the opening 90 and the rotation shaft 64 is rotated, whereby the vertical rotation position of the suspension arm member 35 is adjusted.

  The extension wall portion 73 has a wall shape standing obliquely with respect to the horizontal direction, extends from the front wall portion 71 to the outside in the vehicle width direction, and protrudes from the suspension cross member 20. The suspension arm member 35 is disposed in front of the suspension arm member 35 so as to be separated from the suspension arm member 35 by a predetermined gap G.

The connecting portion 70 is formed in a flat plate shape, and is provided to extend forward from the lower edge portion of the extension wall portion 73 in a state where the flat plate surface 70a is oriented in the vertical direction. That is, the connecting portion 70 extends toward the vehicle front side in a state of protruding from the suspension cross member 20. Further, through holes 86, 86 are formed in the flat plate surface 70a. Then, a fastening member 85 such as a bolt is inserted into the through holes 86 and 86 and tightened with a nut or the like, so that the connecting portion 70 and the rear end portion 21b of the subframe 21 are connected.
According to such a configuration, the connecting portion 70 is provided so as to protrude from the suspension cross member 20 with a simple configuration. Moreover, since the connecting portion 70 and the rear end portion 21b of the subframe 21 are fastened by the fastening member 85, the assemblability is excellent.

The upper wall portion 72 extends from the upper edge portion of the front wall portion 71 to the vehicle rear side, and is disposed above the bush mounting member 50.
The side wall portion 74 is formed in a vertical wall shape, and extends from the front wall portion 71 along the front surface of the front arm support portion 40. The side wall 74 is formed with a vertically long opening 96 for avoiding interference with the welded portion W2 of the bush mounting member 50 described above.

  A flange portion 75 extends from the lower edge portion of the front wall portion 71 and the side wall portion 74. The flange portion 75 is provided orthogonal to the vertical wall-shaped front wall portion 71 and the side wall portion 74 and extends toward the vehicle front side. And it is formed so that it may continue to the connecting part 70 mentioned above.

And the upper wall part 72 and the side wall part 74 of the bracket member 55 are joined to the suspension cross member 20 side by welding in the 1st welding part W3 and the 2nd welding part W4, respectively. The first welding portion W <b> 3 is provided at an edge 72 a on the vehicle rear side of the upper wall portion 72 and is welded to the bush mounting member 50. The second welded portion W4 is provided at the vehicle inner end edge 74a of the side wall portion 74, and is welded to the front surface of the cross member main body 20a. At this time, the welding of the second welding portion W4 is performed in a state where the flange portion 75 of the bracket member 55 is disposed on the flange portion 20b formed on the front edge portion of the suspension cross member 20.
According to such a configuration, the bracket member 55 and the suspension cross member 20 are firmly connected to each other at the side wall portion 74 by welding. At this time, welding can be performed in a state where the flange portion of the bracket member 55 is disposed on the flange portion 20b of the suspension cross member 20, and the welding workability is excellent.

In the vehicle body front structure 10 according to the present embodiment configured as described above, the connecting portions 70 of the bracket members 55 and 56 connected to the sub frames 21 and 22 are provided so as to protrude from the suspension cross member 20 as described above. The flat plate surface 70a is connected to the rear end portions 21b and 22b of the subframes 21 and 22 with, for example, a fastening member 85 in a state in which the flat plate surface 70a is oriented in the vertical direction. For this reason, the bracket members 55 and 56 including the connecting portion 70 function as spring elements that are elastically deformed with the vibration in the vertical direction of the vehicle. That is, the subframes 21 and 22 and the bracket members 55 and 56 can be configured as dynamic dampers using the subframes 21 and 22 as mass bodies and the bracket members 55 and 56 as spring elements.
According to the vehicle body front part structure 10 of the present embodiment as described above, it is transmitted from the suspension cross member 20 to the vehicle body side by using the existing subframes 21 and 22 without using a new heavy object. Vibration can be suppressed.

In this case, it is preferable that the resonance frequency of the dynamic damper including the pair of bracket members 55 and 56 and the pair of subframes 21 and 22 is equal to the resonance frequency of the suspension cross member. .
If comprised in this way, the vibration of the frequency band vicinity which tends to be a problem generally with road noise can be suppressed.

The resonance frequency of the dynamic damper including the pair of bracket members 55 and 56 and the pair of sub frames 21 and 22 is adjusted by appropriately changing the shape, thickness, material, and the like of the bracket members 55 and 56. can do.
For example, as shown in FIG. 5 and FIG. 6, the resonance frequency of the dynamic damper can be adjusted by forming a shape in which a part 72A of the upper wall portion 72 of the bracket member 55 is notched in the embodiment described above. Can do. Further, as shown in FIGS. 5 and 6, the resonance frequency of the dynamic damper can also be adjusted by extending the side wall portion 74 with respect to the above-described embodiment. Further, the resonance frequency of the dynamic damper can be adjusted by changing the thickness and Young's modulus without changing the shapes of the bracket members 55 and 56.

  As mentioned above, although the preferable form of this invention was demonstrated, this invention is not limited to said form, A various change in the range which does not deviate from the objective of this invention is possible.

  At least one embodiment of the present invention can be applied to an automobile including a vehicle body front portion structure having a pair of subframes that connect a vehicle body front end portion and a suspension cross member in the vehicle front-rear direction.

DESCRIPTION OF SYMBOLS 10 Vehicle body front structure 11, 12 Side member 13 Bumper beam 14 Front end cross member 20 Suspension cross member 20a Cross member main body 20b Collar part 21 Subframe 21a Front end part 21b Rear end part 23 Bracket 24 Pulling support member 30 Support members 35, 36 Suspension arm members 35a, 36a Front end portion 40 Front arm support portion 41 Rear arm support portion 45 Front wheels 50, 51 Bush mounting members 55, 56 Bracket member 64 Rotating shaft 70 Connecting portion 70a Flat plate surface 71 Front wall portion 72 Upper wall portion 73 Extension Wall part 74 Side wall part 75 Flange part 85 Fastening member 86 Through-hole 90,96 Opening W1-W4 Welding location

Claims (1)

In the body front structure,
A front end cross member extending in the vehicle width direction at the front end of the vehicle;
A suspension cross member that is positioned on the vehicle rear side with respect to the front end cross member, extends in the vehicle width direction, and supports a suspension arm member;
A pair of sub-frames extending in the front-rear direction of the vehicle, the front ends of which are respectively connected to the front-end cross members;
A pair of bracket members that respectively connect the rear end portions of the pair of subframes and the suspension cross member;
Each of the pair of bracket members is configured as a spring element that is elastically deformed with vibration in the vertical direction of the vehicle, and each of the pair of subframes is a dynamic damper that suppresses vibration in the vertical direction of the vehicle. Configured to function as a mass body ,
A vehicle body front part structure configured such that a resonance frequency of a dynamic damper including the pair of bracket members and the pair of subframes is equal to a resonance frequency of the suspension cross member .

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