JP2013091410A - Vehicle body rear structure of vehicle - Google Patents

Abstract

Even if the separation distance along the vehicle longitudinal direction between a rear bumper and a fuel tank or between a rear bumper and a sub-frame disposed behind the fuel tank is short, it is applied from the rear of the vehicle body. To sufficiently absorb the impact energy and to prevent damage to the fuel tank.
SOLUTION: At a rear portion of a vehicle body 12, two side frames 14 extending in the vehicle longitudinal direction on both sides in the vehicle width direction, a rear cross frame 18 extending in the vehicle width direction, and a rear cross frame 18 are disposed behind. A rear bumper 20 is provided, the fuel tank 22 is disposed in front of the rear cross frame 18 in the longitudinal direction of the vehicle body, and the upstream silencer 32 and the downstream silencer 34 are disposed between the rear cross frame 18 and the rear bumper 20. At the same time, the longitudinal section along the longitudinal direction of the vehicle body is formed in an elliptical shape, and the minor axis T of the elliptical shape is disposed in the longitudinal direction of the vehicle body.
[Selection] Figure 3

Description

  The present invention relates to a vehicle body rear structure in which a fuel tank is disposed at the rear of a vehicle body, and a silencer is disposed laterally along the vehicle width direction behind the fuel tank.

  As a prior art, for example, in Patent Document 1 and Patent Document 2, when a shock is applied from the rear of a vehicle body due to a rear-end collision or the like, a silencer (exhaust silencer) is dropped downward to provide a gap between a rear bumper and a fuel tank. Alternatively, a space (crushing allowance) for absorbing an impact is created between the rear bumper and a rear cross member (horizontal frame member) disposed behind the fuel tank, and the impact is transmitted to the fuel tank. A vehicle body rear structure that reduces fuel consumption and prevents damage to the fuel tank is disclosed.

Japanese Utility Model Publication No. 63-43141 Japanese Utility Model Publication No. 3-26620

  However, in the vehicle body rear structure disclosed in Patent Document 1 and Patent Document 2, for example, a rear cross member (horizontal frame member) disposed between the rear bumper and the fuel tank or at the rear of the rear bumper and the fuel tank. When the separation distance along the longitudinal direction of the vehicle body is set short compared to the conventional case, even if the silencer is dropped downward, the space (crushing allowance) for absorbing the impact is provided. There is a problem that it cannot be produced sufficiently.

  For example, if the distance of the rear overhang is short in relation to the layout at the rear of the vehicle body, the space between the rear bumper and the fuel tank (crushing allowance), or the rear cross member disposed behind the rear bumper and the fuel tank, It is difficult to ensure a sufficient space (crushing allowance). As a result, the crushing allowance for absorbing the impact is reduced, and even if the silencer is dropped downward, the impact energy applied from the rear of the vehicle body cannot be sufficiently absorbed.

  The present invention has been made in view of the above points, and a separation distance along the vehicle body front-rear direction between the rear bumper and the fuel tank or between the rear bumper and the subframe disposed behind the fuel tank. It is an object of the present invention to provide a vehicle body rear structure that can sufficiently absorb impact energy applied from the rear of the vehicle body and reliably prevent damage to the fuel tank even when the vehicle is short.

  In order to achieve the above object, the present invention provides a vehicle body rear structure in which a fuel tank is disposed at the rear of a vehicle body, and a silencer is disposed laterally along the vehicle width direction behind the fuel tank. The silencer is characterized in that a longitudinal section along the longitudinal direction of the vehicle body is formed in an elliptical shape, and the short axis of the elliptical shape is arranged in the longitudinal direction of the vehicle body.

  According to the present invention, the silencer itself is formed, for example, by a rear-end collision, by forming the longitudinal section of the silencer along the longitudinal direction of the vehicle body in an elliptical shape and arranging the short axis thereof in the longitudinal direction of the vehicle body. It can function as an impact energy absorber that sufficiently absorbs impact energy applied from the rear of the vehicle body. As a result, in the present invention, it is possible to prevent impact energy from being applied to the fuel tank disposed in front of the silencer, and to suitably prevent the fuel tank from being damaged.

  That is, the present invention actively uses the silencer as a shock absorber, even when the distance between the rear bumper and the fuel tank, or between the rear bumper and the subframe disposed behind the fuel tank is short. When the silencer is crushed, the impact energy is sufficiently absorbed and the fuel tank can be suitably prevented from being damaged.

  In this case, if the elliptical long axis in the longitudinal section of the silencer is arranged so as to be in the longitudinal direction of the vehicle body, for example, left and right end plates that extend in the longitudinal direction of the vehicle body and are provided on both sides in the vehicle width direction of the silencer Similarly, when the impact energy is transmitted, silencer components such as partition plates that extend in the longitudinal direction of the vehicle body and partition the silencer act to increase the rigidity of the silencer in the direction in which the impact energy is transmitted. In addition, there is a concern that the silencer itself is less likely to be crushed and the impact energy cannot be sufficiently absorbed.

  However, the present invention can reduce the rigidity of the silencer in the direction in which the impact energy is transmitted by arranging the elliptical short axis in the longitudinal section of the silencer in the longitudinal direction of the vehicle body. As a result, the silencer itself can be easily crushed and the impact energy can be sufficiently absorbed, and damage to the fuel tank can be reliably prevented.

  In the present invention, the rear portion of the vehicle body includes two frames extending in the vehicle longitudinal direction on both sides in the vehicle width direction, a subframe connecting the two frames and extending in the vehicle width direction, and behind the two frames. A rear bumper is disposed, the fuel tank is disposed in front of the subframe in a longitudinal direction of the vehicle body, and the silencer is disposed between the subframe and the rear bumper. .

  According to the present invention, for example, when an impact is received from the rear of the vehicle body due to a rear-end collision or the like, the impact energy can be sufficiently absorbed by crushing the silencer, and the subframe has high rigidity compared to other members. Is disposed behind the fuel tank, the fuel tank can be reliably prevented from being damaged.

  Furthermore, the present invention is characterized in that the silencer includes a partition plate that extends in a longitudinal direction of the vehicle body and partitions an internal silencer chamber.

  According to the present invention, it is possible to divide the silencing chamber into, for example, an expansion chamber and a resonance chamber by providing the partition plate, and it is possible to enhance the silencing effect by different attenuation frequencies of the exhaust sound.

  Furthermore, the present invention is characterized in that the silencer comprises a plurality of silencers connected in series in the exhaust gas flow direction.

  According to the present invention, by connecting a plurality of silencers in series in the flow direction of the exhaust gas, the silencing effect can be further enhanced as compared with a single silencer.

  Even when the distance between the rear bumper and the fuel tank or the rear bumper and the sub-frame disposed behind the fuel tank along the vehicle body longitudinal direction is short, the impact energy applied from the rear of the vehicle body Thus, the rear structure of the vehicle body can be obtained which can sufficiently absorb the fuel and reliably prevent the fuel tank from being damaged.

1 is a bottom view of an automobile to which a vehicle body rear structure according to an embodiment of the present invention is applied. It is a perspective view of the vehicle body rear part of the said motor vehicle. It is a longitudinal cross-sectional view along the III-III line of FIG. It is a top view of the vehicle body rear part of the said motor vehicle. It is a partially transparent perspective view of an upstream silencer and a downstream silencer. (A) is the side view which looked at the upstream side silencer and the downstream side silencer from the back of a vehicle body, (b) is the top view which looked at the upstream side silencer and the downstream side silencer from the upper part. (A), (b) is a side view which shows the state where an upstream silencer and a downstream silencer function as an impact energy absorber when impact energy is applied from the rear of a vehicle body by a collision member such as a vehicle. is there.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. 1 is a bottom view of a vehicle to which a vehicle body rear structure according to an embodiment of the present invention is applied, FIG. 2 is a perspective view of the vehicle body rear portion of the vehicle, and FIG. 3 is taken along line III-III in FIG. FIG. 4 is a longitudinal sectional view, and FIG. 4 is a plan view of the rear part of the vehicle body. Note that “front and rear” and “up and down” indicated by arrows in each figure indicate the front and rear direction and vertical direction of the vehicle body, and “left and right” indicate the left and right direction (vehicle width direction) as viewed from the driver's seat. ing.

  As shown in FIG. 1, the rear portion of the vehicle 10 includes a pair of side frames 14 (two frames) extending in the front-rear direction of the vehicle body 12 on the left and right sides in the vehicle width direction, and the center of the vehicle body 12 in the front-rear direction. A middle cross frame 16 that connects the set of side frames 14 slightly rearward and extends in the left-right direction, and a rear that connects the set of side frames 14 in the rear portion of the vehicle body 12 and extends in the left-right direction (vehicle width direction). It has a cross frame (subframe) 18 and a rear bumper 20 supported by an outer panel (not shown) and arranged behind the set of side frames 14.

  Note that the side frame 14, the middle cross frame 16, and the rear cross frame 18 function as a skeleton member constituting the vehicle body 12, and have higher rigidity than other members.

  As shown in FIG. 1 or FIG. 2, at the rear of the vehicle body 12, a fuel tank 22 disposed behind the middle cross frame 16 and in front of the rear cross frame 18 in the front-rear direction of the vehicle body 12, The engine 24 is disposed between the middle cross frame 16 and the rear cross frame 18 and is supported by a mount member (not shown), a transmission mechanism 26, a drive shaft 27, and a plurality of constant velocity joints 28. A rotational driving force transmission device 30 that transmits force to the left and right rear wheels RL and RR is provided. The fuel tank 22 is provided so as to be positioned above the transmission mechanism 26.

  As shown in FIGS. 2 and 4, two silencers including an upstream silencer 32 and a downstream silencer 34 are arranged at the rear portion of the vehicle body 12. The upstream silencer 32 and the downstream silencer 34 are arranged between the rear cross frame 18 and the rear bumper 20 in the front-rear direction of the vehicle body 12 and in the left-right direction (vehicle width direction) behind the fuel tank 22. Along the side.

  In this case, the upstream silencer 32 and the downstream silencer 34 are connected to the converter 24a (see FIG. 1) of the engine 24 via the exhaust pipe 36, and the exhaust gas discharged from the engine 24 is converted into the upstream silencer. 32 and the downstream silencer 34 in this order, and then discharged to the atmosphere via a tail pipe 38 connected to the downstream silencer 34. Note that the exhaust port of the tail pipe 38 is disposed at a substantially central portion in the left-right direction (vehicle width direction) of the vehicle body 12.

  As shown in FIG. 3, the upstream silencer 32 and the downstream silencer 34 have an elliptical longitudinal section along the longitudinal direction of the vehicle body 12, and the elliptical short axis T is the longitudinal direction of the vehicle body. It is arranged to be. This will be described in detail later.

  5 is a partially transparent perspective view of the upstream silencer and the downstream silencer, FIG. 6A is a side view of the upstream silencer and the downstream silencer as seen from the rear of the vehicle body, and FIG. ) Is a plan view of the upstream silencer and the downstream silencer as viewed from above.

  The upstream-side silencer 32 has a pair of end plates 40a and 40b that have the same elliptical shape when viewed from the side and are opposed to each other at a predetermined interval along the flow direction of the exhaust gas, and an elliptical opening. On the other hand, a pair of end plates 40a and 40b are respectively attached to a cylindrical body 44 in which a sound absorbing chamber 42 closed inside and a pair of end plates 40a and 40b are supported. And a tubular body 46 penetrating along the flow direction of the exhaust gas. The tubular body 46 is formed with a plurality of small through holes 48 that allow the flow path in the tubular body 46 to communicate with the sound absorbing chamber 42 in the tubular body 44.

  The sound absorbing chamber 42 in the cylinder 44 is filled with a sound absorbing material (not shown). For example, exhaust gas flowing in the flow path of the tube 46 flows into the sound absorbing chamber 42 through the through small hole 48. For example, the high frequency component of the exhaust sound is absorbed by a sound absorbing material (not shown).

  The downstream-side silencer 34 has a pair of end plates 50a and 50b that have the same elliptical shape when viewed from the side and are opposed to each other at a predetermined interval along the flow direction of the exhaust gas, and the pair of end plates 50a. 50b, a partition plate 56 that is disposed between the pair of end plates 50a, 50b and extends in the front-rear direction of the vehicle body 12, and elliptical openings are formed at both ends along the exhaust gas flow direction. The opening is closed by a pair of end plates 50a and 50b, and includes a cylinder 58 that holds a partition plate 56 disposed substantially at the center. A space (silence chamber) in which the inside of the cylinder 58 is closed is partitioned by a partition plate 56, and an expansion chamber 52 and a resonance chamber 54 are formed with the partition plate 56 interposed therebetween.

  Further, the downstream-side silencer 34 passes through one end plate 50 a adjacent to the upstream-side silencer 32 and the upper side of the partition plate 56 and continues to the tube body 46, and the first end opening faces the expansion chamber 52. A tubular body 60 a, a second tubular body 60 b that is continuous with the tail pipe 38 and that passes through one end plate 50 a close to the upstream silencer 32 and the lower side of the partition plate 56, and has a distal end opening facing the expansion chamber 52. The third tubular body 60c is supported by the partition plate 56 between the first tubular body 60a and the second tubular body 60b, and both end openings face the one and the other end plates 50a and 50b, respectively.

  The third tubular body 60c includes an expansion chamber 52 in which both end openings are not in contact with one and the other end plates 50a and 50b, and are closed by the partition plate 56, the other end plate 50b, and the cylindrical body 58; 56, the resonance chamber 54 closed by the one end plate 50a and the cylindrical body 58 is communicated. The partition plate 56 also functions as a support member that supports the first to third tubular bodies 60a to 60c.

  In this case, the exhaust gas introduced into the expansion chamber 52 via the first tubular body 60a is mainly the second tubular body facing the expansion chamber 52 after the low frequency component of the exhaust sound is attenuated in the expansion chamber 52. 60b and the tail pipe 38 are exhausted to the atmosphere. In the resonance chamber 54 that communicates with the expansion chamber 52 via the third tubular body 60c, for example, specific frequency components such as a high frequency component and a middle frequency component in the exhaust sound that can be heard by the human ear are attenuated. The The specific frequency component is set by the volume of the resonance chamber 54, the length of the pipe line protruding from the partition plate 56 of the third tubular body 60c toward the other end plate 50b, and the like.

  Each end plate 40a, 50b of the upstream-side silencer 32 and the downstream-side silencer 34 is provided with a pair of hanger frames 62 that protrude toward the left and right sides. An elastic body 64 is attached to each hanger frame 62. Each stay 66 fixed to the side frame 14 is attached to the elastic body 64. In this case, the upstream-side silencer 32 and the downstream-side silencer 34 are supported by a pair of side frames 14 disposed on the left and right sides via elastic bodies 64, respectively.

  The vehicle 10 to which the vehicle body rear structure according to the present embodiment is applied is basically configured as described above, and the operation and effect thereof will be described next.

  7A and 7B show a state in which the upstream silencer 32 and the downstream silencer 34 function as an impact energy absorber when impact energy is applied from the rear of the vehicle body by a collision member such as a vehicle. FIG. 7A shows a state before application of impact energy, and FIG. 7B shows a state after application of impact energy.

  The upstream silencer 32 and the downstream silencer 34 are disposed between the rear cross frame 18 and the rear bumper 20 in the front-rear direction of the vehicle body 12, and the longitudinal section along the front-rear direction of the vehicle body 12 has an elliptical shape. It arrange | positions so that the short axis T may become the front-back direction of the vehicle body 12 (refer Fig.7 (a)).

  Therefore, for example, when an impact is received from the rear of the vehicle body 12 due to a vehicle collision or the like, the upstream-side silencer 32 and the downstream-side silencer 34 are directed downward, unlike the prior art (Patent Literature 1 and Patent Literature 2). After falling to the rear cross frame 18 close to the front side of the vehicle body 12 and coming into contact with the rear cross frame 18 without falling, it is sandwiched between the rear cross frame 18 and a collision member such as a vehicle. The impact energy is absorbed by being easily crushed (see FIG. 7B).

  At that time, the upstream silencer 32 and the downstream silencer 34 are arranged so that the longitudinal section along the longitudinal direction of the vehicle body 12 is elliptical and the minor axis T thereof is the longitudinal direction of the vehicle body 12. The rigidity of the pair of end plates 40a, 40b, 50a, 50b and the partition plate 56 constituting the upstream silencer 32 and the downstream silencer 34 can be reduced, and can easily be crushed to sufficiently absorb impact energy. Can do.

  On the other hand, if the elliptical long axes in the longitudinal sections of the upstream silencer 32 and the downstream silencer 34 are arranged so as to be in the front-rear direction of the vehicle body 12, the upstream silencer 32 and the downstream silencer. The rigidity of the pair of end plates 40a, 40b, 50a, 50b and the partition plate 56 constituting the container 34 is increased, and it becomes difficult to be easily crushed and it is difficult to sufficiently absorb the impact energy.

  Thus, in the present embodiment, by causing the upstream silencer 32 and the downstream silencer 34 to function positively as an impact energy absorber that sufficiently absorbs the impact energy applied from the rear of the vehicle body 12, It is possible to prevent impact energy from being applied to the fuel tank 22 disposed in front of the rear cross frame 18 in the front-rear direction of the vehicle body 12, and to appropriately input a large load to the fuel tank 22. .

  In other words, in the present embodiment, the upstream silencer 32 and the downstream silencer 34 are actively used as shock absorbers, and between the rear bumper 20 and the fuel tank 22 or behind the rear bumper 20 and the fuel tank 22. Even when the separation distance from the rear cross frame 18 arranged in the rear is short (when the distance D of the rear overbar hang shown in FIG. 1 is short), the upstream silencer 32 and the downstream silencer 34 are crushed. The impact energy can be sufficiently absorbed, and damage to the fuel tank 22 can be suitably prevented.

  Further, in the present embodiment, for example, when an impact is received from the rear of the vehicle body 12 due to a vehicle collision or the like, the impact energy can be sufficiently absorbed by crushing the upstream silencer 32 and the downstream silencer 34, Since the rear cross frame 18 having high rigidity is disposed behind the fuel tank 22, damage to the fuel tank 22 can be reliably prevented.

  Furthermore, in this embodiment, by providing the partition plate 56 in the downstream silencer 34, the silencer can be divided into, for example, an expansion chamber 52 and a resonance chamber 54, and the exhaust sound attenuation frequency is different. Can enhance the silencing effect.

  Furthermore, in the present embodiment, a plurality of silencers including the upstream silencer 32 and the downstream silencer 34 are connected in series in the flow direction of the exhaust gas, so that compared to a single silencer. The silencing effect can be enhanced.

  In the present embodiment, a plurality of silencers including the upstream silencer 32 and the downstream silencer 34 are described. However, the present invention is not limited to this, and the longitudinal section is formed in an elliptical shape. A single silencer arranged such that its short axis is in the front-rear direction of the vehicle body 12 may be used.

10 Car 12 Car body 14 Side frame (2 frames)
18 Rear cross frame (subframe)
20 Rear bumper 22 Fuel tank 32 Upstream silencer (silencer)
34 Downstream silencer (silencer)
56 Partition plate

Claims (4)

A vehicle body rear structure in which a fuel tank is disposed at the rear of the vehicle body, and a silencer is disposed laterally along the vehicle width direction behind the fuel tank,
A vehicle body rear structure of an automobile, wherein the muffler is arranged such that a longitudinal section along the longitudinal direction of the vehicle body is formed in an elliptical shape, and the short axis of the elliptical shape is in the longitudinal direction of the vehicle body. The vehicle body rear portion includes two frames extending in the vehicle body longitudinal direction on both sides in the vehicle width direction, a sub frame connecting the two frames and extending in the vehicle width direction, and a rear bumper disposed behind the two frames. Is provided,
The fuel tank is disposed in front of the subframe in the longitudinal direction of the vehicle body,
The vehicle body rear structure according to claim 1, wherein the silencer is disposed between the sub-frame and the rear bumper.   The vehicle body rear part structure according to claim 1 or 2, wherein the silencer includes a partition plate extending in a longitudinal direction of the vehicle body and partitioning an internal silencer chamber.   The vehicle body rear part structure according to any one of claims 1 to 3, wherein the silencer includes a plurality of silencers connected in series in a flow direction of exhaust gas.

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