Vehicle underfloor structure

Abstract

To provide a vehicle underfloor structure capable of improving silencing performance of a silencer without enlarging the silencer, and easily securing an arrangement space of the silencer.SOLUTION: In the vehicle underfloor structure, a fuel tank 8 and a muffler 9 are arranged below a floor panel 5. The muffler 9 is positioned in front of the fuel tank 8, and is arranged so that the longitudinal direction is directed in the vehicle width direction, and a clearance S through which traveling air flows is formed between the muffler 9 and the floor panel 5.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle underfloor structure. [Background technology]

[0002] BACKGROUND ART Conventionally, a vehicle underbody structure in which a silencer and a sub-silencer are disposed below a floor panel is known (see Patent Document 1).

[0003] In a conventional vehicle underfloor structure, the silencer is disposed behind the battery, with its longitudinal direction oriented in the vehicle width direction.

[0004] The sub-silencer is located on the right side of the battery, with its longitudinal direction facing the front-to-rear direction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-39452 Summary of the Invention [Problem to be solved by the invention]

[0006] One known method for improving the noise reduction performance of a muffler is to increase its capacity (volume), but in conventional vehicle undercarriage structures, a large battery is located below the floor panel, limiting the space available for arranging the muffler and sub-muffler.

[0007] As a result, if the capacity of the silencer or sub-silencer is increased, the silencer or sub-silencer will become larger, which may make it difficult to secure the space to place the silencer or sub-silencer.

[0008] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a vehicle underfloor structure that can improve the noise mitigating performance of a silencer without increasing the size of the silencer, and can easily ensure space for arranging the silencer. [Means for solving the problem]

[0009] The present invention is a vehicle underfloor structure in which a fuel tank and a silencer are arranged below the vehicle underfloor, and the silencer is located forward of the fuel tank and arranged so that its longitudinal direction faces the vehicle width direction, and a gap is formed between the silencer and the underfloor through which running wind can flow. [Effects of the Invention]

[0010] As described above, according to the present invention, the silencing performance of the silencer can be improved without increasing the size of the silencer, and the space for arranging the silencer can be easily secured. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a bottom view of a hybrid vehicle having a vehicle underfloor structure according to an embodiment of the present invention. [Figure 2] FIG. 2 is a vertical cross-sectional view of a vehicle underfloor structure according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] A vehicle underfloor structure according to one embodiment of the present invention is a vehicle underfloor structure in which a fuel tank and a silencer are arranged below the underfloor of the vehicle, the silencer being positioned forward of the fuel tank and arranged so that its longitudinal direction faces the vehicle width direction, and a gap is formed between the silencer and the underfloor through which wind can flow when the vehicle is running.

[0013] As a result, the vehicle underfloor structure according to one embodiment of the present invention can improve the silencing performance of the silencer without increasing the size of the silencer, and can easily ensure space for arranging the silencer. [Example]

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a vehicle underfloor structure according to the present invention will be described with reference to the drawings. 1 and 2 are diagrams showing a vehicle underfloor structure according to one embodiment of the present invention.

[0015] In Figures 1 and 2, the up / down, front / rear, left / right directions are based on the internal combustion engine installed in a vehicle, and the front / rear direction of the vehicle is the front-rear direction, the left / right direction of the vehicle (vehicle width direction) is the left / right direction, and the up / down direction of the vehicle (vehicle height direction) is the up / down direction.

[0016] First, the configuration will be described. 1, a hybrid vehicle 1 as a vehicle can be driven by an internal combustion engine 2, a first motor generator 3, and a second motor generator (not shown). The hybrid vehicle 1 of this embodiment can be driven in, for example, a series hybrid mode.

[0017] Specifically, the series hybrid mode is a state in which the internal combustion engine 2 and the drive wheels (not shown) are not mechanically connected, and the first motor generator 3 generates electricity using the power of the internal combustion engine 2, while the second motor generator uses the power supplied from the first motor generator 3 to perform motor driving.

[0018] The hybrid vehicle 1 has a left side member 4L and a right side member 4R that are spaced apart in the vehicle width direction and extend in the front-rear direction, and a floor panel 5 that is connected to the left side member 4L and the right side member 4R.

[0019] 2, the upper part of the floor panel 5 constitutes the vehicle interior 6, and a front seat (not shown) is provided in front of the floor panel 5. A rear seat (not shown) is provided above the floor panel 5 and behind the front seat. The floor panel 5 of this embodiment constitutes the underfloor space.

[0020] The hybrid vehicle 1 is provided with a battery pack (not shown), an inverter (not shown), and the like.

[0021] When driving in motor mode, the internal combustion engine 2 and the first motor generator 3 are stopped compared to when driving in series hybrid mode, and the second motor generator functions as an electric motor driven by power supplied only from the battery via an inverter, and also functions as a generator that generates regenerative electricity using the rotational force (reverse driving force) input from the drive wheels.

[0022] Under the control of an ECU (not shown), the inverter converts DC power supplied from the battery pack into three-phase AC power to supply to the second motor generator, and converts three-phase AC power generated by the second motor generator into DC power to charge the battery pack. The battery pack is formed of a secondary battery such as a lithium-ion battery.

[0023] As shown in FIG. 1, one end and the other end of a cross member 7 are connected to the left side member 4L and the right side member 4R below the floor panel 5, respectively, and the cross member 7 extends in the vehicle width direction.

[0024] A fuel tank 8 for storing fuel is disposed below the floor panel 5 and behind the cross member 7, and a silencer 9 is disposed below the floor panel 5 and in front of the cross member 7.

[0025] One end of fuel pipes 8A and 8B is connected to the fuel tank 8, and the other end of the fuel pipes 8A and 8B is connected to a delivery pipe (not shown). The delivery pipe distributes the fuel introduced from the fuel pipes 8A and 8B to injection nozzles (not shown) provided in each of a plurality of cylinders (not shown).

[0026] The silencer 9 is formed in a cylindrical shape and extends in the vehicle width direction. That is, the silencer 9 has a central axis 9L in the longitudinal direction, and is disposed horizontally so that the longitudinal direction faces the vehicle width direction and the short side faces the front-rear direction.

[0027] As shown in FIG. 2, when the hybrid vehicle 1 is viewed from the vehicle width direction, the silencer 9 is formed in an elliptical shape so that it is longer in the front-to-rear direction than in the up-to-down direction, and is gently curved from the front end 9f toward the upper end 9a, and also gently curved from the front end 9f toward the lower end 9b.

[0028] As shown in FIG. 1, the downstream end of an upstream exhaust pipe 10 is connected to the right end of the silencer 9, and the upstream exhaust pipe 10 curves from the right end of the silencer 9 and extends forward toward the internal combustion engine 2.

[0029] Exhaust gas discharged from the internal combustion engine 2 is introduced into the upstream exhaust pipe 10 , and the exhaust gas introduced from the internal combustion engine 2 is introduced into the muffler 9 from the downstream end of the upstream exhaust pipe 10 .

[0030] The upstream end of a downstream exhaust pipe 11 is connected to the right end of the silencer 9, and the downstream exhaust pipe 11 curves from the right end of the silencer 9 and extends rearward.

[0031] The exhaust gas discharged from the muffler 9 is introduced into the downstream exhaust pipe 11, which then discharges the exhaust gas into the atmosphere.

[0032] Here, upstream and downstream refer to the upstream and downstream directions of the exhaust gas flow, with the upstream exhaust pipe 10 located upstream of the downstream exhaust pipe 11, and the downstream exhaust pipe 11 located downstream of the upstream exhaust pipe 10.

[0033] As shown in FIG. 2, the floor panel 5 has, from the front side to the rear side, a front floor panel portion 5A, a middle floor panel portion 5B, and a rear floor panel portion 5C.

[0034] The front floor panel portion 5A is located forward of the silencer 9 and extends in the front-to-rear direction so as to be located at a height position between the upper end 9a and the lower end 9b of the silencer 9. In Figure 2, an imaginary line L1 passing parallel to the upper end 9a of the silencer 9 and an imaginary line L2 passing parallel to the lower end 9b are shown by imaginary lines.

[0035] Further, the front floor panel portion 5A is located at a height substantially equal to the horizontal axis 9H of the silencer 9 that crosses the central axis 9L in the longitudinal direction of the silencer 9 in the horizontal direction.

[0036] The middle floor panel portion 5B extends from the rear end portion 5a of the front floor panel portion 5A above the silencer 9 and covers the silencer 9 from above.

[0037] The rear floor panel portion 5C extends upward from the rear end portion 5b of the intermediate floor panel portion 5B and then extends rearward in the front-to-rear direction. In other words, the intermediate floor panel portion 5B is located higher than the front floor panel portion 5A, and the rear floor panel portion 5C is located higher than the intermediate floor panel portion 5B.

[0038] The rear floor panel portion 5C covers the fuel tank 8 from above, so that the lower portion of the fuel tank 8 faces the silencer 9 in the front-to-rear direction.

[0039] The gap S between the intermediate floor panel portion 5B and the silencer 9 is formed so that the imaginary straight line L connecting the longitudinal center axis 9L of the silencer 9 and the intermediate floor panel portion 5B becomes shorter as it moves from the front end portion 5c of the intermediate floor panel portion 5B upward of the silencer 9. The front end portion 5c of the intermediate floor panel portion 5B and the rear end portion 5a of the front floor panel portion 5A are in the same position.

[0040] In detail, the gap S between the intermediate floor panel portion 5B and the silencer 9 is defined as the distance from the point where the imaginary straight line L connecting the longitudinal center axis 9L of the silencer 9 and the intermediate floor panel portion 5B intersects with the surface of the silencer 9 to the intermediate floor panel portion 5B, and is formed so that it becomes shorter as it moves from the front end portion 5c of the intermediate floor panel portion 5B toward the top of the silencer 9.

[0041] In other words, the gap S between the intermediate floor panel portion 5B and the silencer 9 becomes shorter as it moves from the front of the silencer 9 to the top of the silencer 9, and a gap S through which the running wind flows is formed between the silencer 9 and the intermediate floor panel portion 5B.

[0042] In this embodiment, the front floor panel portion 5A constitutes the front underfloor portion, and the middle floor panel portion 5B constitutes the rear underfloor portion.

[0043] Next, the effects of the vehicle underfloor structure of this embodiment will be described. According to the vehicle underfloor structure of this embodiment, a fuel tank 8 and a silencer 9 are disposed below the floor panel 5 .

[0044] The silencer 9 is located forward of the fuel tank 8 and is arranged so that its longitudinal direction faces the vehicle width direction. The silencer 9 is arranged below and spaced apart from the intermediate floor panel portion 5B, and a gap S through which the airflow flows is formed between the silencer 9 and the intermediate floor panel portion 5B.

[0045] As a result, the traveling wind W (see FIG. 2) flowing from the front of the hybrid vehicle 1 to the silencer 9 is not blocked by the large fuel tank 8, which has a larger volume than the silencer 9. As a result, a larger amount of the traveling wind W can be directed efficiently at the silencer 9.

[0046] The muffler 9 has the characteristic that the lower the internal exhaust gas temperature is, the more efficiently it can muffle noise by suppressing volume expansion. Therefore, by arranging the muffler 9 in a location where it can be efficiently cooled by the running wind W, the muffler 9 can be prevented from becoming larger while improving its muffling performance.

[0047] In this way, the vehicle underfloor structure of this embodiment can improve the silencing performance of the silencer 9 without increasing the size of the silencer 9, and can easily ensure the space for arranging the silencer 9.

[0048] Furthermore, according to the vehicle underfloor structure of this embodiment, the traveling wind W can be directed efficiently at the muffler 9 even when the vehicle speed of the hybrid vehicle 1 is low, so that when traveling at low speeds in series hybrid mode, even if the internal combustion engine 2 rotates at high speeds to charge the battery using the second motor generator, the rise in exhaust gas temperature can be suppressed and muffler performance can be improved.

[0049] Furthermore, according to the vehicle under-floor structure of this embodiment, by arranging the muffler 9 so that its longitudinal direction faces the vehicle width direction, it is possible to extend the length of the exhaust pipe including the upstream exhaust pipe 10 from the internal combustion engine 2 to the muffler 9. This makes it possible to increase the back pressure of the muffler 9, thereby more effectively improving the muffling performance.

[0050] Furthermore, according to the vehicle underfloor structure of this embodiment, the floor panel 5 has a front floor panel portion 5A located forward of the silencer 9, and the front floor panel portion 5A extends in the fore-and-aft direction so as to be located at a height position between the upper end 9a and lower end 9b of the silencer 9.

[0051] This allows the traveling wind W flowing along the underside of the front floor panel portion 5A to hit the front surface of the silencer 9 more effectively, cooling the silencer 9 more effectively and improving the noise absorbing performance of the silencer 9 more effectively.

[0052] Furthermore, since the silencer 9 is formed in an elliptical shape so that it is longer in the front-to-rear direction than it is in the up-and-down direction, the traveling wind W that hits the front surface of the silencer 9 is divided into traveling winds W1 and W2 that flow from the front end 9f to the upper end 9a and lower end 9b of the silencer 9. This allows the upper and lower surfaces of the silencer 9 to be cooled by the traveling winds W1 and W2, and the cooling performance of the silencer 9 can be improved more effectively.

[0053] Furthermore, according to the vehicle underfloor structure of this embodiment, the floor panel 5 has a middle floor panel portion 5B that extends above the silencer 9 from the rear end portion 5a of the front floor panel portion 5A.

[0054] In addition, the gap S between the intermediate floor panel portion 5B and the silencer 9 is formed so that the imaginary straight line L connecting the longitudinal center axis 9L of the silencer 9 and the intermediate floor panel portion 5B becomes shorter as it moves from the front end portion 5c of the intermediate floor panel portion 5B toward above the silencer 9.

[0055] As a result, a larger amount of traveling wind W1 is taken into the intermediate floor panel portion 5B from between the front end portion 5c of the intermediate floor panel portion 5B and the silencer 9 (shown as gap S1 in FIG. 2) ahead of the silencer 9, and then the flow velocity of the traveling wind W1 can be increased by gap S2 between the upper surface of the silencer 9 and the intermediate floor panel portion 5B, which is narrower than the gap between the front end portion 5c of the intermediate floor panel portion 5B and the silencer 9. Note that gap S includes gap S1 and gap S2.

[0056] Therefore, the cooling performance of the silencer 9 can be improved more effectively by the traveling wind W1 having a high flow rate, and the noise absorbing performance of the silencer 9 can be improved more effectively.

[0057] In this embodiment, a hybrid vehicle is used as an example of the vehicle, but the vehicle is not limited to a hybrid vehicle.

[0058] While an embodiment of the present invention has been disclosed, it will be apparent to those skilled in the art that modifications may be made without departing from the scope of the invention, and all such modifications and equivalents are intended to be encompassed by the following claims. [Explanation of symbols]

[0059] 1 Hybrid vehicle (vehicle) 5 Floor panel (under the floor) 5A Front floor panel (front floor lower part) 5B Middle floor panel section (rear floor lower section) 8. Fuel Tank 9 Silencer 9a Upper end (upper end of silencer) 9b Lower end (lower end of silencer) 9L Central axis (longitudinal central axis of silencer) L Imaginary line (imaginary line connecting the longitudinal center axis of the silencer and the rear underfloor) S Gap (gap between the silencer and underfloor)

Claims

1. A vehicle underfloor structure in which a fuel tank and a silencer are disposed below the underfloor of a vehicle, The silencer is located forward of the fuel tank and is disposed so that its longitudinal direction faces the vehicle width direction, A vehicle underfloor structure, wherein a gap through which airflow flows is formed between the muffler and the underfloor.

2. the underfloor section includes a front underfloor section located forward of the silencer, 2. The vehicle under-floor structure according to claim 1, wherein the front under-floor portion extends in the front-rear direction so as to be located at a height position between an upper end and a lower end of the silencer.

3. the underfloor section includes a rear underfloor section extending from a rear end of the front underfloor section to above the silencer, 3. The vehicle underfloor structure according to claim 2, characterized in that the gap between the rear underfloor and the muffler is formed so that an imaginary line connecting the longitudinal center axis of the muffler and the rear underfloor becomes shorter as it moves from the front end of the rear underfloor to above the muffler.

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