JP2007309386A - Vibration damping structure for body structural member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide vibration damping structure for a body structural member, which prevents or effectively suppresses the resonance of the body structural member with specific frequency vibration without increasing the number of component items. <P>SOLUTION: A gravity position G of a mass 50 is offset from a position of fastening the mass 5 to a stepped portion 42. The mass 50 is thereby vibrated around a fastening part of a mounting portion 52 to the stepped portion 42 with the vibration of a vehicle approximately in the vertical direction when travelling. In this way, the vibration damping structure is substantially constructed as a mass damper, but substantially functioned as a dynamic damper. Even when the mass of the mass 50 is smaller than in the case of using the mass damper, the same effect is obtained as in the case of providing the mass damper. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a damping structure for a vehicle body structural member for reducing vibrations of various members constituting the vehicle body.

As a vehicle body damping structure, for example, as disclosed in Patent Document 1 below, a vehicle body structure member (referred to as a body predetermined portion in Patent Document 1), an example of which is a front header. ) Has a configuration to install a mass damper. By adding the mass of the mass constituting the mass damper to the mass of the vehicle body structural member, the mass of the entire vehicle body structural member is changed, and the inherent frequency of the vehicle body structural member is shifted. Thereby, for example, resonance of the vehicle body structural member with respect to vibration of a specific frequency that is a main factor of abnormal noise is prevented or effectively suppressed.
JP-A-11-325170

  However, in order to prevent or effectively suppress the resonance of the vehicle body structural member with respect to specific vibration with such a mass damper, a mass with a large mass must be attached to the vehicle body structural member. On the other hand, for example, when the dynamic damper is provided on the vehicle body structural member, the resonance of the vehicle body structural member with respect to the vibration of a specific frequency can be prevented or effectively suppressed even if the mass of the mass is small. However, in the configuration in which the dynamic damper is provided, an elastic member such as a spring must be provided between the mass and the vehicle body structural member. For this reason, the number of parts increases and the cost increases.

  In view of the above facts, the present invention has an object to obtain a damping structure for a vehicle body structural member that can prevent or effectively suppress resonance of the vehicle body structural member with respect to vibration of a specific frequency without increasing the number of parts. is there.

  A vibration damping structure for a vehicle body structural member according to a first aspect of the present invention includes a mass body whose center of gravity is offset from a fixed position with respect to the vehicle body structural member.

  In the vibration damping structure for a vehicle body structural member according to the first aspect of the present invention, the position of the center of gravity of the mass body fixed to the vehicle body structural member is offset with respect to the fixed position with the vehicle body structural member (that is, The position of the center of gravity of the mass body is separated from the position where the mass body is fixed to the vehicle body structural member). For this reason, the center of gravity of the mass body vibrates around the fixed position with the vehicle body structural member. The vibration of the mass body cancels the vibration of the vehicle body structural member, and the resonance of the vehicle body structural member with respect to the vibration of a specific frequency is prevented or effectively suppressed.

  That is, the present invention does not include any special elastic means, but the mass body constitutes a so-called “dynamic damper”. For this reason, adding mass to the vehicle body structural member, that is, by providing a mass damper, the mass of the mass body is far less than the configuration that prevents or suppresses resonance of the vehicle body structural member with respect to vibration of a specific frequency. Can be small.

  A vibration damping structure for a vehicle body structural member according to a second aspect of the present invention is the vibration damping structure for a vehicle body structural member according to the first aspect, wherein the mass body is fixed to the vehicle body structural member in a state where the mass body is fixed to the vehicle body structural member. The mass body includes a support body that is separated from the vehicle body structural member on the position of the center of gravity with respect to the position.

  In the vibration damping structure for a vehicle body structural member according to the second aspect of the present invention, the mass body is supported by the support so that the mass body is separated from the vehicle body structural member on the center of gravity position side of the mass body. For this reason, when the mass body vibrates at the center of gravity position, the vehicle body structural member does not interfere with the mass body. As described above, the mass body can vibrate without being interfered with the vehicle body structural member, so that the resonance of the vehicle body structural member with respect to the vibration of a specific frequency is reliably prevented or effectively suppressed.

  A vibration damping structure for a vehicle body structural member according to a third aspect of the present invention is the vibration damping structure for a vehicle body structural member according to the second aspect, wherein the mass body, the vehicle body structural member, and the mass body are fixed to the vehicle body structural member. The supporting body is integrally provided on any one of the fixing means.

  In the vibration damping structure for a vehicle body structural member according to the third aspect of the present invention, since the support body is provided integrally with any one of the mass body, the vehicle body structural member, and the fixing means, In addition, the mass body can be separated from the vehicle body structural member without increasing the number of parts.

  As described above, the vehicle body structural member damping structure according to the first aspect of the present invention is much smaller than the configuration in which the mass damper is provided without providing an elastic member such as a spring or rubber. The mass body of the mass can prevent or effectively suppress the resonance of the vehicle body structural member with respect to the vibration of a specific frequency.

  In the vibration damping structure for a vehicle body structural member according to the second aspect of the present invention, since the mass body can vibrate without being interfered with the vehicle body structural member by providing the support body, the vehicle body against vibration at a specific frequency is provided. The resonance of the structural member can be reliably prevented or effectively suppressed.

  In the vibration damping structure for a vehicle body structural member according to the third aspect of the present invention, the mass body can be separated from the vehicle body structural member without substantially increasing the number of parts, and by providing the support body An increase in cost can be prevented or effectively suppressed.

    <Configuration of First Embodiment>

  FIG. 1 is an enlarged cross-sectional view of the vicinity of a front end portion of a vehicle roof 10 to which a vehicle body structural member damping structure according to a first embodiment of the present invention is applied. In each of the drawings including FIG. 1, the arrow FR indicates the front of the vehicle and the arrow UP indicates the upper side of the vehicle. As shown in FIG. 1, a front header 14 as a vehicle body structural member is provided on the lower side in the vicinity of the front end portion of the roof panel 12 constituting the roof 10 (in the direction opposite to the arrow UP in FIG. 1). . The front header 14 includes a header outer panel 16. The header outer panel 16 includes an upper wall 18. The upper wall 18 is formed in a flat plate shape whose longitudinal direction is substantially along the vehicle left-right direction and whose width direction is substantially along the vehicle front-rear direction.

  A vertical wall 20 extends from one end (front end) in the width direction of the upper wall 18 substantially toward the vehicle lower side. A flange 22 extends from the end of the vertical wall 20 opposite to the upper wall 18 toward the front side of the vehicle. The flange 22 overlaps with a flange 24 provided integrally with the flange 22 on the front end side of the roof panel 12. On the other hand, the vertical wall 26 extends from the other end (rear end portion) in the width direction of the upper wall 18 toward the vehicle lower side. A flange 28 extends from the end opposite to the upper wall 18 of the vertical wall 26 toward the space between the roof panel 12 and the dome lamp bracket 30 on the substantially vehicle rear side.

  A header inner panel 32 is provided below the header outer panel 16 having the above configuration. The header inner panel 32 includes a bottom wall 34. The bottom wall 34 is formed in a flat plate shape whose longitudinal direction is substantially along the vehicle left-right direction and whose width direction is substantially along the vehicle front-rear direction, and is provided below the top wall 18. A vertical wall 36 extends from one end (front end portion) in the width direction of the bottom wall 34 substantially toward the vehicle upper side. A flange 38 extends from the end of the vertical wall 36 opposite to the bottom wall 34 toward the vehicle front side. The flange 38 overlaps the flange 22 below the flange 22.

  The flange 22 and the flange 38 are integrally coupled by fixing means such as welding or fastening means such as bolts, whereby the header outer panel 16 and the header inner panel 32 are located in front of the intermediate portion in the width direction of the front header 14. And are integrally coupled. Further, the flange 22 and the flange 38 thus coupled are further integrally coupled to the flange 24 by fixing means such as welding or fastening means such as bolts, and the roof panel 12 and the front header 14 are integrally formed. Combined.

  On the other hand, the vertical wall 40 extends substantially upward from the end of the bottom wall 34 opposite to the vertical wall 36. A step portion 42 as a support is formed from the upper end portion of the vertical wall 40 toward the vehicle rear side. The step portion 42 is formed in a flat plate shape whose longitudinal direction is substantially along the vehicle left-right direction and whose width direction is substantially along the vehicle front-rear direction. A vertical wall 44 extends substantially upward from the end of the step portion 42 opposite to the vertical wall 40. A flange 46 extends from the upper end of the vertical wall 44 toward the vehicle rear side.

  The flange 46 overlaps the flange 28 on the lower side of the flange 28, and the flange 46 is integrally coupled to the flange 28 by fixing means such as welding or fastening means such as bolts. Thereby, the header outer panel 16 and the header inner panel 32 are integrally coupled to the rear side of the intermediate portion in the width direction of the front header 14.

  The front header 14 constituted by the header outer panel 16 and the header inner panel 32 having the above-described configuration is formed in a hollow shape with a closed cross section, and both ends in the vehicle lateral direction are welded to a roof side rail (not shown). They are integrally connected by fastening means such as fixing means and bolts.

  Further, as shown in FIG. 1, a mass 50 as a mass body is provided inside the front header 14. The mass 50 includes a block-like or plate-like attachment portion 52. The rear side of the intermediate portion of the attachment portion 52 substantially along the vehicle front-rear direction is placed on the step portion 42. A through hole 54 is formed on the rear end side of the attachment portion 52 so as to penetrate in the thickness direction of the attachment portion 52 (more specifically, the thickness direction of the attachment portion 52 in the same direction as the thickness direction of the step portion 42). Yes. A through hole 56 is formed in the step portion 42 corresponding to the through hole 54. From the lower side of the through hole 56, a bolt 58 constituting a mass fixing means as a fastening member passes through the through hole 54 and further passes through the attachment portion 52.

  The bolt 58 that has penetrated the attachment portion 52 is screwed with a nut 60 provided on the upper surface side of the attachment portion 52, whereby the attachment portion 52 is mechanically connected to the stepped portion 42. A mass body 62 is formed continuously from the end of the mounting portion 52 on the substantially vehicle front side. The mass body 62 is integrally formed with the mounting portion 52 as a mass 50 by the same material as the step portion 42. The mass main body 62 has a dimension in at least one of the vertical direction, the horizontal direction, and the thickness direction larger than that of the attachment portion 52, and therefore, the mass of the mass main body 62 is larger than that of the attachment portion 52. As a result, the center of gravity G of the mass 50 is located closer to the mass main body 62 than the mounting portion 52.

  Further, as shown in FIG. 1, the mounting portion 52 is positioned on the step portion 42 with respect to the intermediate portion in the vehicle front-rear direction, but the front portion is more than the step portion 42 with respect to the intermediate portion in the vehicle front-rear direction. The front side is located above the bottom wall 34. In the mass body 62 that is continuous from the mounting portion 52, a predetermined gap D <b> 1 is formed with respect to the bottom wall 34 between the bottom wall 34 and the top wall 18. The thickness of the mass body 62 is set so that the gaps D1 and D2 are formed with respect to both the upper wall 18 and the bottom wall 34. )

    <Operation and Effect of First Embodiment>

  Next, the operation and effect of the present embodiment will be described.

  In the vehicle to which the present embodiment is applied, for example, a moment around the fastening portion between the mounting portion 52 and the stepped portion 42 is generated in the mass 50 due to the vibration in the vertical direction of the vehicle that occurs when the vehicle travels. The mass 50 (that is, a part of the attachment portion 52 and the mass main body 62) vibrates around the fastening portion between the attachment portion 52 and the step portion 42 on the bottom wall 34 side of the step portion 42.

  In this way, the mass 50 that can vibrate with a predetermined mass is provided in the step portion 42, so that, for example, the low frequency side with respect to the frequency at which the in-vehicle sound increases or the frequency at which the in-vehicle sound increases is interposed between the low frequency. The resonance frequency of the front header 14 is changed to be divided into both the high frequency side and the high frequency side. In this way, by changing the resonance frequency of the front header 14, for example, it is possible to prevent or effectively suppress the generation of abnormal noise caused by the resonance of the front header 14 due to vibration during vehicle travel.

  In this embodiment, the mass is provided in the front header 14 and is structurally the same as the mass damper. However, since the mass 50 can vibrate as described above, a spring or the like is provided. Although not provided, a dynamic damper is substantially constituted. For this reason, the mass of the mass 50 is sufficiently smaller than the mass of the mass (mass body) having a simple mass damper, and the same effect can be obtained, for example, by 1/2 or less. Thereby, it is possible to set the mass 50 that can reduce the cost, contribute to the weight reduction of the vehicle body, and can obtain a sufficient effect in a very limited narrow space inside the front header 14.

  Further, the same effect can be obtained even if a general dynamic damper is provided inside the front header 14, but the general dynamic damper elastically connects the mass and the front header 14 in addition to the mass. Elastic means are required. On the other hand, in the present embodiment, it is only necessary to provide the configuration in which the gravity center position G is separated from the fastening portion between the stepped portion 42 and the mounting portion 52, and the mass 50 may be provided. For this reason, compared with the structure which provides a general dynamic damper in the inside of the front header 14, a number of parts can be decreased and member cost and an assembly man-hour can be reduced.

    <Configuration of Second Embodiment>

  Next, other embodiments of the present invention will be described. In describing each of the following embodiments, the same parts as those in the previous embodiment are basically the same as those in the embodiment described above including the first embodiment. Reference numerals are assigned and detailed description thereof is omitted.

  FIG. 2 is an enlarged cross-sectional view of the vicinity of the front end portion of the vehicle roof 10 to which the vehicle body structural member damping structure according to the second embodiment of the present invention is applied. As shown in this figure, the vehicle to which the present embodiment is applied is provided with a front header 72 as a vehicle body structural member on the lower side of the roof panel 12 instead of the front header 14. The front header 72 includes a header inner panel 74 that replaces the header inner panel 32.

  The header inner panel 74 includes a bottom wall 76 instead of the bottom wall 34. The bottom wall 76 is formed in a flat plate shape whose longitudinal direction is substantially along the vehicle left-right direction and whose width direction is substantially along the vehicle front-rear direction. A vertical wall 36 is formed continuously from one end (front end) in the width direction of the bottom wall 76. On the other hand, a vertical wall 78 is formed continuously from the other end (rear end) in the width direction of the bottom wall 76 toward the upper side of the vehicle, and the flange 46 extends from the upper end of the vertical wall 78. .

  A support portion 80 is formed at the other end in the width direction of the bottom wall 76. The support part 80 includes a cylindrical part 82. The cylindrical portion 82 is formed in a cylindrical shape having an open lower end along the thickness direction of the bottom wall 76, and is provided inside the front header 72. The upper end portion of the cylindrical portion 82 is formed by plastically deforming the bottom wall 76 upward in the thickness direction. The inner diameter dimension of the cylindrical portion 82 is set sufficiently larger than the outer diameter dimension of the head of the bolt 58. The axially upper end of the cylindrical portion 82 is closed by the upper bottom portion 84, and the rear side of the intermediate portion of the mounting portion 52 substantially along the vehicle front-rear direction is placed on the upper bottom portion 84.

  Similar to the state in which the attachment portion 52 is placed on the step portion 42 in the first embodiment, in the state in which the attachment portion 52 is placed on the upper bottom portion 84, the mass main body 62, the bottom wall 76, A predetermined gap D <b> 1 is formed between the mass body 62 and the upper wall 18, and a predetermined gap D <b> 2 is formed between the mass body 62 and the upper wall 18. , That is, the protruding dimension of the support portion 80 with respect to the upper surface of the bottom wall 76 is set.

  The depth dimension of the support portion 80 from the lower opening end of the cylindrical portion 82 to the upper bottom portion 84 is the dimension of the head of the bolt 58 along the axial direction of the bolt 58 (that is, the depth of the head of the bolt 58). (Thickness dimension) or more is set. A through hole 86 corresponding to the through hole 54 is formed in the upper bottom portion 84, and the bolt 58 passes through the through hole 86 and further passes through the through hole 54 and the nut 60 is screwed. The head of the vertical wall 78 is accommodated inside the support portion 80.

    <Operation and Effect of Second Embodiment>

  Next, the operation and effect of the present embodiment will be described.

  In the vehicle to which the present embodiment is applied, for example, a moment centered on the fastening portion between the attachment portion 52 and the upper bottom portion 84 is generated in the mass 50 due to the vibration in the vertical direction of the vehicle that occurs when the vehicle travels. The mass 50 (that is, a part of the attachment portion 52 and the mass main body 62) vibrates around the fastening portion between the attachment portion 52 and the upper bottom portion 84 at the front side of the vehicle substantially from the upper bottom portion 84. As described above, this embodiment also has the same effect as the first embodiment. For this reason, the same effect as the first embodiment can be obtained.

  Further, the present embodiment also has a configuration in which a mass 50 is provided in a front header 72 instead of the front header 14 and a configuration in which the gravity center position G is separated from the fastening portion between the upper bottom portion 84 and the attachment portion 52. However, the configuration is the same as that of the first embodiment in that only the mass 50 is provided. Therefore, the same effect as that of the first embodiment can be obtained also in this point.

  Further, in the present embodiment, the cylindrical portion 82 is provided above the bottom wall 76, and the heads of the bolts 58 disposed inside the cylindrical portion 82 are also positioned above the bottom wall 76. That is, in the present embodiment, since the head of the bolt 58 does not protrude below the bottom wall 76, the front header 72 is assembled to the roof panel 12 or the roof side rail, and other members are assembled to the front header 72. Therefore, the head of the bolt 58 does not get in the way, and the workability of such assembling work can be improved.

    <Configuration of Third Embodiment>

  Next, a third embodiment of the present invention will be described. FIG. 3 shows an enlarged cross-sectional view of the vicinity of the front end portion of the vehicle roof 10 to which the vehicle body structural member damping structure according to the present embodiment is applied. As shown in this figure, a vehicle to which the present embodiment is applied has a front header 92 as a vehicle body structural member that replaces the front header 72 in the first embodiment provided on the lower side of the roof panel 12. Yes. The header inner panel 94 constituting the front header 92 has a bottom wall 96. The bottom wall 96 basically has the same structure as the bottom wall 76, but the support portion 80 is not formed, and the through-hole 56 is formed in the same manner as the step portion 42 in the first embodiment. The configuration is different from the bottom wall 76.

  Inside the front header 92, a mass 98 is provided as a mass body in place of the mass 50. The mass 98 includes a block-shaped mounting portion 100 as a support. A through hole 54 is formed in the mounting portion 100, and a bolt 58 that passes through the through hole 56 of the bottom wall 96 passes through the through hole 54 of the mounting portion 100. In a state where the nut 60 is screwed into the bolt 58 that penetrates the through hole 56, the lower end of the mounting portion 100 is in contact (pressure contact) with the upper surface of the bottom wall 96. A mass main body 102 is provided substantially on the vehicle front side of the mounting portion 100.

  The mass main body 102 is formed in a block shape whose dimension along at least one of the vertical direction, the horizontal direction, and the thickness direction is larger than that of the mounting portion 100, and the mounting portion 100 is above the lower end portion of the mounting portion 100. Are integrally connected to each other. For this reason, the center-of-gravity position G of the entire mass 98 is located substantially on the vehicle front side with respect to the mounting portion 100. Further, as described above, the mass body 102 is integrally connected to the attachment portion 100 above the lower end portion of the attachment portion 100, so that a predetermined gap D1 is provided between the mass body 102 and the bottom wall 96. Is formed. In addition, the thickness of the mass body 102 is set so that a predetermined gap D <b> 2 is formed between the mass body 102 and the upper wall 18.

    <Operation and Effect of Third Embodiment>

  Next, the operation and effect of the present embodiment will be described.

  In the vehicle to which the present embodiment is applied, for example, the mass 98 has a moment around the fastening portion of the mass 98 and the bottom wall 96, that is, the mounting portion 100, with vibration in the vehicle vertical direction that occurs when the vehicle travels. As a result, the mass body 102 vibrates around the attachment portion 100. For this reason, the present embodiment also has the same effect as the first embodiment. Therefore, the present embodiment can provide the same effects as those of the first embodiment.

  In addition, the present embodiment also has a configuration in which a mass 98 is provided on a front header 92 instead of the front header 14, and the center of gravity position G is a fastening portion between the bottom wall 96 and the mass 98 (that is, the attachment portion 100). The configuration is the same as that of the first embodiment in that the mass 98 only needs to be provided. Therefore, the same effect as that of the first embodiment can be obtained also in this point.

  Furthermore, in the present embodiment, a configuration in which the mass body 102 is positioned above the bottom wall 96 (that is, a configuration for forming the gap D1 between the mass body 102 and the bottom wall 96) is replaced with the bottom wall 96. It was formed in the attachment part 100 which is a part of the mass 98 without forming it. For this reason, it is not necessary to apply special processing to the bottom wall 96 in order to position the mass body 102 above the bottom wall 96. For example, this embodiment can be easily applied to a vehicle to which the present invention is not applied. Applicable form.

    <Configuration of Fourth Embodiment>

  Next, a fourth embodiment of the present invention will be described. FIG. 4 shows an enlarged cross-sectional view of the vicinity of the front end portion of the vehicle roof 10 to which the vehicle body structural member damping structure according to the present embodiment is applied. As shown in this figure, the present embodiment has a configuration in which the mass 50 in the first and second embodiments is provided instead of the mass 98 in the third embodiment.

  Further, in the present embodiment, a sleeve 112 as a support is provided between the attachment portion 52 and the bottom wall 96. The sleeve 112 is formed in a cylindrical shape through which the bolt 58 can be passed, and is disposed in a substantially coaxial state with respect to both the through hole 54 of the mounting portion 52 and the through hole 56 of the bottom wall 96. The axial dimension of the sleeve 112 is set to be larger than the length from the lower end surface of the attachment portion 52 along the thickness direction of the mass 50 to the lower end surface of the mass main body 62, and the dimension between the attachment portion 52 and the bottom wall 96 is set. A predetermined gap D <b> 1 is formed between the mass body 62 and the bottom wall 96 by interposing the sleeve 112 therebetween.

    <Operation and Effect of Fourth Embodiment>

  In the present embodiment configured as described above, a mass 50 is provided in place of the mass 98 inside the front header 92 in the third embodiment. Therefore, basically the same operation as the first embodiment can be achieved, and the same effect as the first embodiment can be obtained.

  In this embodiment, the sleeve 112 is provided, and therefore the number of parts increases by the amount of the sleeve 112 provided. However, the configuration in which the mass body 62 is positioned above the bottom wall 96 (that is, the configuration for forming the gap D1 between the mass body 62 and the bottom wall 96) is not required to be formed in the bottom wall 96. Good. For this reason, it is not necessary to apply special processing to the bottom wall 96 in order to position the mass body 62 above the bottom wall 96. For example, this embodiment can be easily applied to a vehicle to which the present invention is not applied. Applicable form.

  In the above-described embodiments, the masses 50 and 98 are attached to the header inner panels 32, 74, and 94 with the bolts 58. However, the masses 50 and 98 may be attached to the header outer panel 16.

    <Configuration of Fifth Embodiment>

  Next, a fifth embodiment of the present invention will be described. FIG. 5 is an enlarged cross-sectional view showing the vicinity of the front end portion of the vehicle roof 10 to which the vehicle body structural member damping structure according to the present embodiment is applied. As shown in this figure, in the present embodiment, the mass 50 and the mass 98 are not arranged inside the front header 92 as in the third and fourth embodiments. A mass 122 as a mass body instead of the mass 98 is provided below the bottom wall 96 (that is, outside the front header 92). The mass 122 includes an attachment portion 124 as a support. The attachment portion 124 is formed in a block shape. The attachment portion 124 is formed with a through hole 126 that penetrates the attachment portion 124 in the thickness direction, and a bolt 58 that penetrates the through hole 56 of the bottom wall 96 from the inside of the front header 92 penetrates the through hole 126. ing.

  The bolt 58 penetrating through the through hole 126 is screwed into a nut 60 provided on the lower surface side of the mounting portion 124, whereby the mass 122 is fastened and fixed to the bottom wall 96. A mass main body 128 is formed continuously from the side surface of the attachment portion 124 on the front side of the vehicle. The mass body 128 has a thickness dimension smaller than that of the attachment portion 124, but a dimension along at least one of the vertical direction and the horizontal direction is larger than that of the attachment portion 124. Is greater than the mass of For this reason, the position of the center of gravity of the mass 122 is located substantially in front of the vehicle with respect to the attachment portion 124.

  In addition, as described above, the thickness dimension of the mass body 128 is smaller than the thickness dimension of the attachment portion 124, and the mass body 128 is continuously formed from the lower side of the middle portion in the thickness direction of the attachment portion 124. Yes. For this reason, a predetermined gap D <b> 3 is formed between the upper surface of the mass body 128 and the lower surface of the bottom wall 96.

    <Operation and Effect of Fifth Embodiment>

  Next, the operation and effect of the present embodiment will be described.

  In the vehicle to which the present embodiment is applied, for example, a moment centering on the fastening portion between the attachment portion 124 and the bottom wall 96 is generated in the mass 122 due to vibrations in the substantially vertical direction of the vehicle that occur when the vehicle travels. The mass 122 vibrates around the fastening portion between the mounting portion 124 and the bottom wall 96 on the substantially vehicle front side of the bottom wall 96. In this way, the mass 122 that can vibrate with a predetermined mass is provided on the bottom wall 96, so that, for example, the low frequency side with respect to the frequency at which the in-vehicle sound increases or the frequency at which the in-vehicle sound increases is sandwiched between low frequencies. The resonance frequency of the front header 92 is changed to be divided into both the high frequency side and the high frequency side. In this way, by changing the resonance frequency of the front header 92, for example, it is possible to prevent or effectively suppress the occurrence of abnormal noise caused by the resonance of the front header 92 due to vibration during vehicle travel.

  In this embodiment, the mass 122 is provided on the front header 92 and is structurally the same as the mass damper. However, since the mass 122 can vibrate as described above, a spring or the like is provided. Although not provided, a dynamic damper is substantially constituted. For this reason, the mass of the mass 122 is sufficiently smaller than the mass of the mass (mass body) having a simple mass damper configuration, and for example, the same effect can be obtained when the mass is 1/2 or less. Thereby, it is possible to set the mass 122 that can reduce the cost, contribute to the weight reduction of the vehicle body, and can obtain a sufficient effect in a very limited narrow space inside the front header 92.

  Further, the same effect can be obtained by providing a general dynamic damper below the bottom wall 96. However, the general dynamic damper elastically connects the mass and the bottom wall 96 in addition to the mass. An elastic means is required. On the other hand, in the present embodiment, it is only necessary to provide the configuration in which the gravity center position G is separated from the fastening portion between the bottom wall 96 and the attachment portion 124, and the mass 122 may be provided. For this reason, compared with the structure which provides a general dynamic damper in the inside of the front header 92, a number of parts can be decreased and member cost and an assembly man-hour can be reduced.

  In each of the above embodiments, the present invention is applied to the front headers 14, 72, 92. However, the present invention is not limited to the front headers 14, 72, 92, and various members constituting the vehicle body. In particular, the effect can be exhibited by applying to a part where a large mass cannot be provided or an elastic member cannot be provided together with the mass.

It is sectional drawing which shows the structure of the principal part of the vehicle to which the damping structure of the vehicle body structural member which concerns on the 1st Embodiment of this invention is applied. It is sectional drawing corresponding to FIG. 1 which shows the structure of the principal part of the vehicle to which the damping structure of the vehicle body structural member which concerns on the 2nd Embodiment of this invention is applied. It is sectional drawing corresponding to FIG. 1 which shows the structure of the principal part of the vehicle to which the damping structure of the vehicle body structural member which concerns on the 3rd Embodiment of this invention is applied. It is sectional drawing corresponding to FIG. 1 which shows the structure of the principal part of the vehicle to which the damping structure of the vehicle body structural member which concerns on the 4th Embodiment of this invention is applied. It is sectional drawing corresponding to FIG. 1 which shows the structure of the principal part of the vehicle to which the damping structure of the vehicle body structural member which concerns on the 5th Embodiment of this invention is applied.

Explanation of symbols

14 Front header (body structural member)
42 Step (support)
50 mass
58 bolts (fixing means)
72 Front header (body structural member)
80 Support (support)
92 Front header (body structural member)
98 Mass (mass body)
100 Mounting part (support)
112 Sleeve (support)
122 Mass (mass body)
G Center of gravity position

Claims (3)

  A vibration damping structure for a vehicle body structural member including a mass body whose center of gravity is offset from a fixed position with the vehicle body structural member.   A support body that separates the mass body from the vehicle body structure member at a position closer to the center of gravity than a position where the mass body is fixed to the vehicle body structure member in a state where the mass body is fixed to the vehicle body structure member. Item 4. A structure for damping a vehicle body structural member according to Item 1.   The said support body is integrally provided in any one of the said mass body, the said vehicle body structural member, and the fixing means which fixes the said mass body to the said vehicle body structural member of Claim 2 characterized by the above-mentioned. Damping structure for car body structural members.

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