Body structure for vehicle

Abstract

To facilitate mounting of a mass damper and reduce an area of a hollow closed cross-section of a cylindrical frame for storing the mass damper.SOLUTION: In a vehicle body structure including a mass damper 30 that is housed in a cylindrical frame 24 and reduces vibration of the frame 24, the mass damper 30 is formed in a band plate shape and housed along a length direction of the frame 24; a center portion in the length direction of the mass damper 30 composes a band-plate-shaped weight portion 31; both end parts of the mass damper 30 in the length direction compose fixed flange portions 37, which are fixed to an inner wall surface of the frame 24; and a pair of elastically deformable portions 34 are provided between the weight portion 31 and the fixed flange portions 37 of the mass damper 30.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a vehicle body structure having a mass damper that is housed within a cylindrical frame and reduces vibration of the frame. [Background technology]

[0002] A conventional technology relating to a vehicle body structure is described in Patent Document 1. As shown in the vertical cross-sectional view of FIG. 7, the vehicle body structure described in Patent Document 1 includes a front header 110, which is a cylindrical frame constituting the front end of a roof portion 100 of the vehicle. The front header 110 is configured to extend in the vehicle width direction and supports an upper edge 102u of a windshield 102. Therefore, when the vehicle is traveling, vibrations of the engine, transmission, etc. are transmitted from the windshield 102, etc. to the front header 110. As a result, the vibration level increases in the part of the front header 110 that is lighter than the windshield 102, and a low-frequency muffled sound is generated in the cab R.

[0003] In order to improve this point, in the body structure of the vehicle, as shown in Fig. 7, a mass damper 105 of a predetermined weight is attached in a front header 110 so as to be capable of vertical vibration. Here, the mass damper 105 is composed of a mass 106 which is a block-shaped mass body, and a bolt and nut 115 which fixes the rear end of the mass 106 to an inner panel 114 of the front header 110. A step portion 114d is formed in the inner panel 114 of the front header 110 to which the mass damper 105 is fixed. Then, the rear end of the mass 106 is fixed to the inner panel 114 on the high surface side (rear side) of the step portion 114d, and a gap is formed between the inner panel 114 on the low surface side (front side) of the step portion 114d and the lower surface of the mass 106.

[0004] When vibrations are transmitted from the windshield 102 to the front header 110 while the vehicle is running, the inner panel 114 on the high side (rear side) of the step portion 114d elastically deforms, allowing the mass 106 to vibrate up and down. In this way, since the mass damper 105 of a predetermined weight is mounted in the front header 110 in a state in which it can vibrate up and down, the vibration level of the front header 110 decreases, making it possible to reduce muffled noise in the cab R. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-309386 A Summary of the Invention [Problem to be solved by the invention]

[0006] The mass damper 105 used in the body structure of the vehicle described above is configured to use a mass 106, which is a block-shaped mass body, as shown in Fig. 7. For this reason, the area of ​​the hollow closed cross section of the front header 110 needs to be large so that the mass 106 can be stored in a state in which it can vibrate up and down. As a result, the front header 110 needs to be formed into a large cylindrical shape. In addition, the rear end of the mass damper 105 is fixed to the inner panel 114 of the front header 110 by bolts and nuts 115, and a step portion 114d needs to be formed in the inner panel 114, so that installation of the mass damper 105 is also time-consuming.

[0007] The present invention has been made to solve the above-mentioned problems, and the problem that the present invention aims to solve is to make it easier to install a mass damper and to reduce the area of ​​the hollow closed cross-section of a cylindrical frame that houses the mass damper. [Means for solving the problem]

[0008] The above-mentioned problems are solved by the following inventions. A first invention is a vehicle body structure including a mass damper that is housed in a cylindrical frame and reduces vibration of the frame, the mass damper is formed in a band-like shape and is housed along the length of the frame, a central portion of the mass damper in the length direction constitutes a band-like weight portion, both ends of the mass damper in the length direction constitute fixed flange portions that are fixed to an inner wall surface of the frame, and a pair of elastic deformation portions that are capable of elastic deformation are provided between the weight portion and the fixed flange portion of the mass damper.

[0009] According to the present invention, the mass damper is formed in a band-like shape and is housed in the frame along the length direction, and the fixing flanges at both ends of the mass damper are fixed to the inner wall of the frame. Therefore, when the frame vibrates while the vehicle is traveling, the pair of elastic deformation parts elastically deform, causing the weight part at the center of the mass damper to vibrate in the plate thickness direction. This reduces the vibration level of the frame and reduces the booming sound in the cab. In this way, when attaching the mass damper, it is no longer necessary to process a step part or the like on the inner wall of the frame as in the conventional method, and therefore the mass damper can be easily attached. In addition, since the mass damper is formed in a band-like shape and housed in the frame along the length direction, the area of ​​the hollow closed cross section of the cylindrical frame can be made smaller than that of a conventional block-shaped mass damper.

[0010] According to the second aspect of the present invention, the weight portion, the elastic deformation portion, and the fixed flange portion of the mass damper are integrally formed from the same material, which makes it easier to manufacture the mass damper.

[0011] According to the third aspect of the present invention, the weight portion, the elastic deformation portion, and the fixed flange portion of the mass damper are formed to have equal thicknesses, which makes it possible to form the mass damper by press molding.

[0012] According to a fourth aspect of the present invention, the elastic deformation portion of the mass damper is provided with a plurality of cutout portions, and the cutout portions make the width dimension of the elastic deformation portion smaller than the width dimension of other portions, thereby making the elastic deformation portion more easily elastically deformable than other portions. In other words, the weight portion, elastic deformation portion, and fixed flange portion of the mass damper are formed from the same material, and the actual width dimension of the elastic deformation portion is reduced to make it easier to elastically deform, thereby reducing costs compared to when the elastic deformation portion is formed from a different material.

[0013] According to the fifth aspect of the present invention, the elastic deformation portion of the mass damper has cutout portions alternately formed on one end side and the other end side in the width direction. That is, the elastic deformation portion can be formed into a substantially S-shape in plan view, so that the length and width dimensions of the elastic deformation portion can be suitably adjusted.

[0014] According to the sixth invention, the frame is a front header that forms the front end of the roof portion of the vehicle and supports the upper edge of the windshield, and the mass damper is formed from a steel plate and a fixing flange portion of the mass damper is spot welded to the inner wall surface of the front header. Effect of the Invention

[0015] According to the present invention, the mass damper can be easily attached, and the area of ​​the hollow closed cross section of the cylindrical frame that houses the mass damper can be reduced. [Brief description of the drawings]

[0016] [Figure 1] 1 is a perspective view of a vehicle equipped with a body structure according to a first embodiment of the present invention, viewed from above, front left. [Diagram 2] FIG. 2 is a plan view of a roof portion of a vehicle equipped with the body structure. [Diagram 3] 3 is a vertical cross-sectional view (a vertical cross-sectional view taken along the line III-III in FIG. 2 ) illustrating a relationship between a front header of a roof portion that constitutes the body structure and a mass damper. [Figure 4] FIG. 2 is a perspective view of the mass damper as viewed from above and in the front left; [Diagram 5] FIG. 4 is a plan view showing the relationship between the mass damper and a front header of the roof portion. [Figure 6] 1 is a graph showing the function of a mass damper. [Figure 7] FIG. 1 is a vertical cross-sectional view showing a body structure of a conventional vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] [Embodiment 1] Hereinafter, a vehicle body structure according to a first embodiment of the present invention will be described with reference to Fig. 1 to Fig. 6. The vehicle body structure according to this embodiment uses a mass damper to reduce vibrations of the front header of the roof of the vehicle, thereby reducing booming noise in the cab. Here, front, rear, left, right, top, bottom, and bottom in the drawings correspond to front, rear, left, right, top, and bottom of the vehicle.

[0018] <Overview of the front part of the vehicle body 10> As shown in Fig. 1, front door openings 13 that are opened and closed by front doors 12 are provided on both the left and right sides of the driver's cab R of a vehicle body 10. Left and right front pillars 14 are erected at the front end positions of the left and right front door openings 13, and the left and right sides of the front end portion of a roof portion 20 are supported by these front pillars 14. The front pillars 14 include a pillar support portion 14x covered by a fender panel 19, and a pillar main body portion 14m that protrudes upward from the fender panel 19 and forms a window frame.

[0019] 1 and 2, the roof section 20 of the vehicle body 10 is provided with a front header 24, which is a cylindrical frame extending in the left-right direction at the front end position. The roof section 20 is also provided with roof side rails 25, which are cylindrical frames extending in the front-rear direction of the vehicle on both left and right sides. The roof side rails 25 are provided on extensions of the pillar main body portion 14m of the front pillar 14. In addition, a plurality of frames (not shown) extending in the left-right direction are provided at equal intervals in the front-rear direction of the vehicle between the left and right roof side rails 25.

[0020] 1 and 2, the entire roof section 20 surrounded by the front header 24 and the roof side rails 25 is covered by a roof panel 22. The roof panel 22 is formed with a plurality of beads 22r (four in the figure) extending in the front-to-rear direction of the vehicle in order to ensure the strength of the roof panel 22. In addition, the windshield 18 is attached to the vehicle body 10 at a position surrounded by the front header 24 of the roof section 20 and the pillar main body portions 14m of the left and right front pillars 14.

[0021] <About Front Header 24> 3, the front header 24 of the roof portion 20 is composed of a header upper panel 241 having a flat inverted U-shaped cross section and a header lower panel 242 having a flat U-shaped groove-shaped cross section. The header upper panel 241 and the header lower panel 242 are formed with front flange portions 241f, 242f and rear flange portions 241b, 242b, respectively. The front flange portion 241f and the rear flange portion 241b of the header upper panel 241 are aligned and joined with the front flange portion 242f and the rear flange portion 242b of the header lower panel 242, respectively, to form the front header 24 into a cylindrical shape.

[0022] As shown in Fig. 3, the front end flange portion 22f of the roof panel 22 is joined in an overlapping state to the front flange portions 241f, 242f of the front header 24. The upper end edge 18u of the windshield 18 is fixed in an overlapping state from above to the front end flange portion 22f of the roof panel 22. In addition, as shown in Figs. 3 to 5, a mass damper 30 is stored in the front header 24, and both longitudinal ends of the mass damper are attached to the header lower panel 242.

[0023] <About Mass Damper 30> The mass damper 30 is a weight member that reduces vibrations of the front header 24 while the vehicle is running, thereby reducing muffled noise in the driver's cab R. As shown in Figs. 4 and 5, the mass damper 30 is a strip-shaped steel plate member that is attached to the center portion in the longitudinal direction of the front header 24, and is stored along the longitudinal direction of the front header 24.

[0024] 4, a strip-shaped weight portion 31 is provided at the center in the longitudinal direction of the mass damper 30. The weight portion 31 is a portion that vibrates up and down (in the plate thickness direction) as a weight for the mass damper 30, and has an escape hole 31n formed in the left end portion to avoid interference with a protrusion (not shown) of the header lower panel 242.

[0025] One end side (left side) and the other end side (right side) in the longitudinal direction of the weight portion 31 of the mass damper 30 are connected to left and right central step portions 32, respectively. In addition, left and right elastic deformation portions 34 are provided on the longitudinal outer sides of the left and right central step portions 32. The central step portion 32 is bent and formed between the weight portion 31 and the elastic deformation portion 34 into a substantially Z-shaped cross section. As a result, the weight portion 31 is held at a position higher than the elastic deformation portion 34 by the height of the central step portion 32.

[0026] The elastic deformation portion 34 of the mass damper 30 is a portion that supports the weight portion 31 in a state in which it can vibrate up and down, and is configured to be capable of elastic deformation when the weight portion 31 vibrates up and down. The elastic deformation portion 34 is formed with the same width dimension as the weight portion 31, and has substantially U-shaped notches 34c formed alternately on one end side and the other end side in the width direction. These notches 34c form the elastic deformation portion 34 into a substantially S-shape in plan view. In other words, the elastic deformation portion 34 is configured so that its actual width dimension is sufficiently smaller than that of other portions such as the weight portion 31, and as a result, its strength is lower than that of other portions, enabling it to be elastically deformed.

[0027] Left and right end step portions 35 are provided on the outer sides in the longitudinal direction of the left and right elastic deformation portions 34, and left and right fixed flange portions 37 are provided on the outer sides in the longitudinal direction of the left and right end step portions 35. The end step portions 35 are bent and formed into a substantially Z-shaped cross section between the elastic deformation portions 34 and the fixed flange portions 37. As a result, the elastic deformation portions 34 are held at a position higher than the fixed flange portions 37 by the height of the end step portions 35. The fixed flange portions 37 form both ends of the mass damper 30 in the longitudinal direction, and are fixed to the bottom surface of the header lower panel 242 of the front header 24 by spot welding.

[0028] As described above, the elastic deformation portion 34 is held at a position higher than the fixed flange portion 37 by the height of the end side step portion 35, and the weight portion 31 is held at a position higher than the elastic deformation portion 34 by the height of the center side step portion 32. Therefore, the weight portion 31 of the mass damper 30 is held at a position higher than the fixed flange portion 37 by the height of the center side step portion 32 and the end side step portion 35. As a result, the weight portion 31 of the mass damper 30 is disposed at the center in the height direction of the internal space of the front header 24, as shown in Fig. 3. That is, a space is secured inside the front header 24 that allows the weight portion 31 of the mass damper 30 to vibrate up and down.

[0029] The mass damper 30 is formed, for example, by press-molding a steel plate having a thickness of 3.2 mm. That is, the weight portion 31, the central step portion 32, the elastic deformation portion 34, the end step portions 35, and the fixed flange portion 37 that constitute the mass damper 30 are integrally molded. Here, the length dimension L and the width dimension W of the mass damper 30 are set, for example, to L = approximately 600 mm and W = approximately 60 mm, and the weight M of the mass damper 30 is set, for example, to M = approximately 750 g.

[0030] <Installation of Mass Damper 30> The mass damper 30 is attached to the front header 24 before the front header 24 is assembled. That is, as shown in FIG. 5, the mass damper 30 is positioned at a predetermined central position of the header lower panel 242 along the length direction of the header lower panel 242. Then, the fixing flange portions 37 at the left and right ends of the mass damper 30 are spot welded to the header lower panel 242. Next, the front flange portion 241f and the rear flange portion 241b of the header upper panel 241 of the front header 24 are aligned with the front flange portion 242f and the rear flange portion 242b of the header lower panel 242, respectively, and are spot welded. As a result, the front header 24 is formed into a cylindrical shape extending in the vehicle width direction, and in this state, the mass damper 30 is housed in the front header 24, completing the attachment of the mass damper 30.

[0031] <How Mass Damper 30 Works> When the vehicle is running, vibrations from the engine, transmission, etc. are transmitted from the windshield 18 etc. to the front header 24. This causes the vibration level to increase in the parts of the front header 24 that are lighter than the windshield 18. When the front header 24 vibrates, the elastic deformation portions 34 on the left and right sides of the mass damper 30 elastically deform, causing the weight portion 31 to vibrate in the vertical direction (plate thickness direction). This reduces the vibration level of the front header 24, making it possible to reduce muffled noise inside the cab R.

[0032] In Fig. 6, the horizontal axis represents vibration frequency (Hz) and the vertical axis represents the sound pressure level of the muffled noise (dB). Here, dotted line II is a graph in the case where a front header 24 without a mass damper 30 is used, and solid line I is a graph in the case where a front header 24 with a mass damper 30 is used. As shown in Fig. 6, by attaching a mass damper 30 to the front header 24, it is possible to effectively reduce the muffled noise around 45 Hz that is unpleasant to the driver.

[0033] <Advantages of the body structure of the vehicle according to this embodiment> According to the vehicle body structure of this embodiment, the mass damper 30 is formed in a strip shape and is stored along the length direction of the front header 24 (frame), and the left and right fixing flange parts 37 of the mass damper 30 are fixed to the inner wall part of the front header 24. Therefore, when the front header 24 vibrates while the vehicle is traveling, the left and right elastic deformation parts 34 elastically deform, causing the weight part 31 at the center of the mass damper 30 to vibrate in the vertical direction (plate thickness direction). This reduces the vibration level of the front header 24, and reduces the muffled sound in the cab R. In this way, when attaching the mass damper 30, it is no longer necessary to process a step part or the like on the inner wall part of the front header 24 as in the conventional case, and therefore the mass damper 30 can be easily attached. In addition, since the mass damper 30 is formed in a strip shape and stored along the length direction of the front header 24, the area of ​​the hollow closed cross section of the front header 24 can be made smaller than that of a conventional block-shaped mass damper.

[0034] Moreover, the weight portion 31, the elastic deformation portion 34, and the fixed flange portion 37 of the mass damper 30 are integrally formed from the same material (steel plate). Furthermore, the weight portion 31, the elastic deformation portion 34, and the fixed flange portion 37 of the mass damper 30 are formed with the same wall thickness. This allows the mass damper 30 to be press-formed, making the mass damper 30 easy to manufacture. Furthermore, the elastic deformation portion 34 of the mass damper 30 has cutout portions 34c formed alternately at one end side and the other end side in the width direction. That is, the actual width dimension of the elastic deformation portion 34 is reduced to make the elastic deformation portion 34 easy to elastically deform, so that costs can be reduced compared to when the elastic deformation portion 34 is formed from a different material. Furthermore, since the elastic deformation portion 34 can be formed into a substantially S-shaped planar shape, the length dimension and width dimension of the elastic deformation portion 34 can be well adjusted.

[0035] <Example of change> Here, the present invention is not limited to the above embodiment, and modifications are possible within the scope of the present invention. For example, in the present embodiment, an example is shown in which the elastic deformation portion 34 is provided by forming the notches 34c alternately at one end side and the other end side in the width direction of the band-shaped mass damper 30. However, instead of forming the elastic deformation portion 34 by the notches 34c, it is also possible to form the elastic deformation portion 34 by processing the band-shaped folded portion. Also, in the present embodiment, an example is shown in which the mass damper 30 is formed by press-molding a steel plate. However, for example, it is also possible to use a resin having a weight approximately equal to that of the steel plate and mold the mass damper by injection molding. It is also possible to insert a steel plate or the like into a weight portion forming portion in a molding die and mold the mass damper by injection molding of the resin. Furthermore, although an example is shown in which the mass damper 30 is attached to the front header 24 of the roof portion 20, the mass damper 30 can also be attached to the roof side rail 25 of the roof portion 20 or the like. [Explanation of symbols]

[0036] 18. Windshield 20 Roof section 24····Front header (frame) 241···Header upper panel 242···Header lower panel 30 Mass damper 31 Weight section 34 Elastic deformation part 34c...Notch 37 Fixed flange R... Driver's cab

Claims

1. A vehicle body structure including a mass damper housed in a cylindrical frame to reduce vibration of the frame, The mass damper is formed in a band shape and is stored along a longitudinal direction of the frame, a central portion of the mass damper in a longitudinal direction constitutes a band-shaped weight portion, and both ends of the mass damper in a longitudinal direction constitute fixed flange portions fixed to an inner wall surface of the frame, A vehicle body structure, wherein a pair of elastically deformable portions capable of elastic deformation are provided between the weight portion and the fixed flange portion of the mass damper.

2. 2. A vehicle body structure according to claim 1, A vehicle body structure in which the weight portion of the mass damper, the elastic deformation portion, and the fixed flange portion are integrally molded from the same material.

3. A vehicle body structure according to claim 2, A vehicle body structure, wherein the weight portion of the mass damper, the elastic deformation portion, and the fixed flange portion are formed with equal thickness dimensions.

4. A vehicle body structure according to claim 3, the elastic deformation portion of the mass damper includes a plurality of cutout portions, A vehicle body structure in which the cutout portion makes the width dimension of the elastically deforming portion smaller than the width dimension of other parts, thereby making the elastically deforming portion more susceptible to elastic deformation than other parts.

5. A vehicle body structure according to claim 4, A vehicle body structure, wherein the cutout portions are formed alternately on one end side and the other end side in the width direction of the elastic deformation portion of the mass damper.

6. A vehicle body structure according to any one of claims 2 to 5, The frame is a front header that constitutes a front end portion of a roof portion of a vehicle and supports an upper edge of a windshield, The mass damper is formed of a steel plate, and a fixing flange portion of the mass damper is spot welded to the inner wall surface of the front header.

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