JP2018030478A - Vehicle exterior noise reduction structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle exterior noise reduction structure which enables simplification of a structure of a noise insulation cover for reducing vehicle exterior noise caused by driving of an engine.SOLUTION: A cab-over type vehicle 10 includes: a pair of left and right side frames 12; an engine 15 located between the pair of left and right side frames 12; a flexible pipe 21 which is located between the engine 15 and the one side frame 12R, forms a part of an exhaust passage 20 of the engine 15, and absorbs vibration transmitted from the engine 15; and a noise insulation cover 30 which shields noise caused by driving of the engine 15. The noise insulation cover 30 extends in a fore and aft direction of the vehicle 10 at the outer side of the vehicle 10 relative to the one side frame 12R and overlaps with an oil pan 17 of the engine 15 and the flexible pipe 21 in a width direction of the vehicle 10 at an area below the one side frame 12R.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle exterior noise reduction structure that reduces vehicle exterior noise associated with engine driving in a cab-over type vehicle.

  In a cab-over type vehicle such as a truck, a vehicle body frame is configured by a pair of left and right side frames and a cross member spanned between the pair of left and right side frames, and an engine disposed inside the pair of left and right side frames. A cab is mounted above the.

  In such a cab-over type vehicle, noise due to vibration of an oil pan or the like is generated as the engine is driven. Such noise propagates to the side of the vehicle and becomes external noise that is felt by people outside the vehicle. Therefore, Patent Document 1 discloses that the engine is covered from below with an undercover having a concave housing portion that houses an oil pan in order to reduce noise outside the vehicle.

JP 2000-73781 A

  By the way, the noise outside the vehicle due to the driving of the engine includes noise due to vibration of a flexible pipe constituting a part of the exhaust passage. The flexible pipe vibrates by absorbing vibrations transmitted through the exhaust passage and by being influenced by exhaust. For this reason, if the engine and the flexible pipe are covered with the under cover as in Patent Document 1, the structure of the cover becomes complicated. Therefore, it is required to reduce the noise outside the vehicle with a soundproof cover having a simple structure.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle exterior noise reduction structure that can reduce vehicle exterior noise that accompanies driving an engine with a simple soundproof cover.

  A vehicle exterior noise reduction structure that solves the above problem is located between a pair of left and right side frames, an engine located between the pair of left and right side frames, and one of the engine and the pair of left and right side frames, A flexible pipe that constitutes a part of the exhaust passage of the engine and absorbs vibrations transmitted through the exhaust passage; and a soundproof cover that reduces outside noise caused by driving of the engine. The vehicle extends in the front-rear direction of the vehicle outside the side frame and overlaps the oil pan of the engine and the flexible pipe below the one side frame in the width direction of the vehicle. .

  According to the above configuration, the soundproof cover overlaps the oil pan and the flexible pipe, which are noise generation sources, in the width direction of the vehicle. Therefore, the noise generated in the oil pan or the flexible pipe and propagated to the side of the vehicle through the space below the one side frame can be effectively shielded by the soundproof cover. Thereby, the noise outside a vehicle accompanying the drive of an engine can be reduced. In addition, the space outside the vehicle relative to the one side frame has fewer parts, wiring, and the like than the space inside the pair of left and right side frames, so that the degree of freedom regarding the shape of the soundproof cover is high. Therefore, the soundproof cover that overlaps the oil pan and the flexible pipe in the width direction of the vehicle can be formed with a simple structure. That is, according to the said structure, the noise outside a vehicle accompanying the drive of an engine can be reduced with the soundproof cover of a simple structure.

  In the above exterior noise reduction structure, the soundproof cover is connected to the front wall portion, the rear wall portion located on the rear side of the vehicle with respect to the front wall portion, the front wall portion, and the rear wall portion. It is good to have the offset wall part which offsets the said rear wall part with respect to the wall part in the width direction of the said vehicle.

  According to the said structure, the rigidity of a soundproof cover can be improved because the front wall part and the rear wall part are offset in the width direction of a vehicle. Thereby, since the natural frequency of the soundproof cover is increased, the soundproof cover is less likely to resonate with respect to the vibration of the vehicle.

In the above exterior noise reduction structure, it is preferable that the soundproof cover has a lower end wall portion extending from a lower end edge of the rear wall portion to the inside of the vehicle.
According to the above configuration, since the soundproof cover has the lower end wall portion, it is possible to reduce the diffracted sound that goes around from the lower end portion of the soundproof cover to the outside of the vehicle. Thereby, the noise outside the vehicle can be further reduced.

  In the exterior noise reduction structure, the soundproof cover includes a first region facing the oil pan in the width direction of the vehicle, a second region facing the flexible pipe in the width direction of the vehicle, and the first region. And an inspection port formed in a region different from the second region, and a sound absorbing material attached to a surface facing the inside of the vehicle and covering at least part of the first region or at least part of the second region It is preferable to have.

  According to the above configuration, (a) at least part of the first region, (b) at least part of the second region, (c) at least part of both the first region and the second region, Any of (c) is covered with a sound absorbing material. Thereby, since the reflected sound reflected in the 1st field or the 2nd field is reduced, the outside noise resulting from this reflected sound can be reduced. In addition, since the inspection port is formed in a region different from the first region and the second region, it is possible to improve the workability of the inspection while reducing the increase in vehicle exterior noise caused by the formation of the inspection port. .

In the above exterior noise reduction structure, it is preferable that the soundproof cover has a rear end wall portion extending from the rear end edge of the rear wall portion to the inside of the vehicle.
According to the above configuration, since the soundproof cover has the rear end wall portion, it is possible to reduce the diffracted sound of the noise propagating obliquely rearward of the vehicle.

  In the above exterior noise reduction structure, the soundproof cover includes a thick member connected to the one side frame via a bracket, and the oil pan connected to the thick member in the width direction of the vehicle. And it is preferable to have the thin member which overlaps with the said flexible pipe as a structural member.

  According to the said structure, weight reduction of a soundproof cover can be achieved, improving the rigidity of the part to which the bracket of a soundproof cover is connected.

The perspective view which shows the perspective structure of one Embodiment of a noise reduction structure outside a vehicle. The side view which shows an example of the side structure of the vehicle in the soundproof cover vicinity. The perspective view which abbreviate | omits a part of member and shows an example of the perspective structure of a soundproof cover. The top view which shows an example of the soundproof cover seen from the inner side of the vehicle. The schematic diagram which shows typically the test method of an acceleration running noise test. The graph which shows an example of the result of an acceleration running noise test.

With reference to FIGS. 1-6, one Embodiment of a noise reduction structure outside a vehicle is demonstrated.
As shown in FIG. 1, a body frame of a cab-over type vehicle 10 includes a pair of left and right side frames 12 that extend in the front-rear direction of the vehicle 10 along the width direction (left-right direction) of the vehicle 10 and the pair of left and right side frames. 12 and a plurality of cross members (not shown) spanned by 12. Inside the pair of left and right side frames 12, an engine 15 and an exhaust passage 20 of the engine 15 are disposed. In FIG. 1, only the right side frame 12R, which is one side frame, is shown, and only a part of the members of the engine 15 and the exhaust passage 20 are shown.

  The engine 15 is connected to each of the pair of left and right side frames 12 via brackets and the like (not shown), and is positioned at the approximate center in the width direction of the vehicle 10. The engine 15 includes a bottom forming member 16 that forms the bottom of the engine 15, and the bottom forming member 16 is located in a region below the pair of left and right side frames 12. The bottom forming member 16 has an oil pan 17 that is a part storing oil supplied to various parts of the engine 15 at a part near the rear of the vehicle 10. Since the oil pan 17 is less rigid than the other parts of the bottom forming member 16, it is likely to vibrate. Due to such vibration, the oil pan 17 generates noise as the engine 15 is driven.

  The exhaust passage 20 is connected to the exhaust manifold of the engine 15, and extends toward the lower side of the vehicle 10 on the side frame 12 </ b> R side and then curves toward the rear of the vehicle 10. A region below the frame 12 extends rearward of the vehicle 10. A flexible pipe 21 is disposed in a portion extending rearward of the vehicle 10. The flexible pipe 21 is located below the engine 15 and on the rear side of the vehicle 10, absorbs vibration from the engine 15 that transmits the exhaust passage 20, and also discharges high-speed exhaust discharged from the engine 15. Vibrates by flowing in. Such vibration causes the flexible pipe 21 to generate noise as the engine 15 is driven.

  A leaf spring 23 constituting a leaf suspension is connected to each of the pair of left and right side frames 12. The leaf spring 23 has an end connected to a spring bracket 24 fixed to the side frame 12 via a shackle 25, and extends below the side frame 12 along the front-rear direction of the vehicle 10. ing. The leaf spring 23 is connected at its central portion to a front axle (not shown).

  A soundproof cover 30 is attached to the side frame 12R. The soundproof cover 30 is located outside the vehicle 10 with respect to the side frame 12R and the leaf spring 23 and in a region inside the vehicle 10 with respect to the front tire 26. The soundproof cover 30 is attached to the side frame 12R via a pair of front brackets 31, 32 and a rear bracket 33. The soundproof cover 30 is attached to the side frame 12R by being fastened to the brackets 31 to 33 connected to the side frame 12R by fastening members. As shown in FIG. 2, the soundproof cover 30 extends in the front-rear direction of the vehicle 10 like a curtain hanging from the side frame 12 </ b> R, and its front end portion is in front of the vehicle 10 than the oil pan 17, and thereafter The end portion is located behind the vehicle 10 with respect to the flexible pipe 21. The soundproof cover 30 overlaps the oil pan 17 and the flexible pipe 21 so as to cover almost the entire oil pan 17 and the flexible pipe 21 in a side view of the vehicle 10 from the side frame 12R side. The soundproof cover 30 that overlaps the oil pan 17 and the flexible pipe 21 has an area of 80% or more, more preferably 90% or more of the projected area of the oil pan 17 and the flexible pipe 21 in the width direction of the vehicle 10. Opposite.

  The soundproof cover 30 includes a front wall portion 35 to which the pair of front brackets 31 and 32 are fastened, a rear wall portion 36 to which the rear bracket 33 is fastened, and the rear wall portion 36 to the front wall portion 35. And an offset wall portion 37 that is located on the outer side of the vehicle 10 at the rear side of the vehicle 10. The soundproof cover 30 includes a lower end wall portion 38 extending from the lower end edge of the rear wall portion 36 toward the inside of the vehicle 10, that is, toward the noise generation source side, and a rear end of the rear wall portion 36 toward the inner side of the vehicle 10. And a rear end wall portion 39 extending from the edge. Each wall portion constitutes an upper end portion of the soundproof cover 30 and the first component member 40 to which the brackets 31 to 33 are fastened. The oil pan 17 and the first component member 40 are joined to the first component member 40 in the width direction of the vehicle 10. It is formed by the second component member 50 that overlaps the flexible pipe 21. Each of the first component member 40 and the second component member 50 is formed, for example, by pressing a steel plate.

  As shown in FIGS. 2 and 3, the first component member 40 is a thick member formed of a steel plate having a larger plate thickness than the second component member 50, and has a higher rigidity than the second component member 50. Have. The first component member 40 has a first front wall portion 41 to which the pair of front brackets 31 and 32 are fastened, a first rear wall portion 42 to which the rear bracket 33 is fastened, and the first front wall portion 41. And a first offset wall 43 that offsets the first rear wall 42 to the outside of the vehicle 10. Further, the first rear wall portion 44 extends from the rear edge of the first rear wall portion 42 toward the inside of the vehicle 10. A pair of front side fastening holes 45 and 46 for fastening the soundproof cover 30 to the front side brackets 31 and 32 are formed in the first front wall portion 41 side by side in the front-rear direction of the vehicle 10. These front side fastening holes 45 and 46 have a long hole shape in which the major axis direction is set in the front-rear direction of the vehicle 10. The first rear wall portion 42 is formed with a pair of rear side fastening holes 47 and 48 for fastening the soundproof cover 30 to the rear side bracket 33 side by side in the front-rear direction of the vehicle 10.

  The second component member 50 is a thin member formed of a steel plate having a thickness smaller than that of the first component member 40, and has a lower rigidity than the first component member 40. The second component member 50 includes a second front wall portion 51 joined to the first front wall portion 41, a second rear wall portion 52 joined to the first rear wall portion 42, and a second front wall portion 51. On the other hand, the second rear wall 52 is offset to the outside of the vehicle 10 and has a second offset wall 53 having a shape following the first offset wall 43.

  The second component member 50 includes a second rear end wall portion 54 that extends from the rear end edge of the second rear wall portion 52 toward the inside of the vehicle 10 that is a noise generation source side, and a noise generation source side. A lower inclined wall 55 that extends from the lower end edge of the second rear wall portion 52 toward the inside of the vehicle 10 and constitutes the lower end wall portion 38 is provided. The lower inclined wall 55 is inclined with respect to the second rear wall portion 52 so that the angle between the lower inclined wall 55 and the second rear wall portion 52 becomes an obtuse angle and overlaps the flexible pipe 21, and the tip portion thereof is the first one. 2 Located on the outside of the vehicle 10 with respect to the front wall portion 51. A bent piece 56 extending upward is formed at the rear end portion of the lower inclined wall 55, and the bent piece 56 is joined to the second rear end wall portion 54.

  The first component member 40 and the second component member 50 are joined by welding, the front wall portion 35 is configured by the first and second front wall portions 41, 51, and the first and second rear wall portions 42, The rear wall portion 36 is constituted by 52, and the offset wall portion 37 is constituted by the first and second offset wall portions 43, 53. Further, the first and second rear end wall portions 44 and 54 constitute a rear end wall portion 39.

  The soundproof cover 30 includes a connecting member 60 that constitutes a connecting wall portion that connects the front end portion of the lower end wall portion 38 and the lower end portion of the offset wall portion 37. The connecting member 60 is formed in a substantially L-shape, and has a rear side joining part 60R joined to the front end part of the lower end wall part 38 and a front side joining part 60F joined to the lower end part of the offset wall part 37. doing.

  The soundproof cover 30 has a first reinforcing plate 65 joined to the outside of the vehicle 10 with respect to the first rear wall portion 42 of the first component member 40. The first reinforcing plate 65 increases the mechanical strength of the part by thickening the part to which the rear bracket 33 is fastened. The first reinforcing plate 65 is joined to the first component member 40 by welding.

  The soundproof cover 30 has an inspection port 68 in the rear wall portion 36. The inspection port 68 is formed at a position that does not overlap the oil pan 17 and the flexible pipe 21 in the width direction of the vehicle 10. The inspection port 68 is formed across the first component member 40 and the second component member 50, and is used, for example, when maintenance is performed on the shackle 25 that supports the leaf spring 23 or the like. The soundproof cover 30 may have an open / close door that can open and close the inspection port 68.

  As shown in FIG. 4, the soundproof cover 30 has a front sound absorbing material 71 and a rear sound absorbing material 72 on a surface facing the inside of the vehicle 10. The front sound absorbing material 71 is attached to the second front wall portion 51 of the second component member 50, and the rear sound absorbing material 72 is a second rear wall portion 52 and a second offset wall of the second component member 50. It is attached to the part 53. These sound absorbing materials 71 and 72 are attached so as to cover a part of the first region 73 facing the oil pan 17 and a part of the second region 74 facing the flexible pipe 21. Each of the sound absorbing materials 71 and 72 can be made of, for example, glass wool or rock wool, and is attached to the second component member 50 by a clip or the like (not shown).

The operation of the vehicle exterior noise reduction structure having the above-described configuration will be described.
The soundproof cover 30 overlaps the oil pan 17 and the flexible pipe 21 that are the sources of outside vehicle noise in the width direction of the vehicle 10. Therefore, among the noises generated from these generation sources, it is possible to effectively shield the noise propagating to the side of the vehicle 10 through the space below the side frame 12R.

  In addition, in the space inside the pair of left and right side frames 12, the engine 15 and the exhaust passage 20 described above, as well as many components, piping, wiring, and the like are arranged. The soundproof cover disposed in such a space inevitably has a complicated shape because it is necessary to shield the noise described above while avoiding interference with components, piping, and wiring. Such a soundproof cover tends to increase in weight and cost. In this regard, the above-described soundproof cover 30 is disposed in a space outside the vehicle 10 with respect to the side frame 12R. Since the space outside the vehicle 10 relative to the side frame 12R has fewer parts, piping, wiring, and the like than the space inside the pair of left and right side frames 12, the degree of freedom regarding the shape of the soundproof cover is high. Therefore, the soundproof cover 30 that overlaps the oil pan 17 and the flexible pipe 21 in the width direction of the vehicle 10 can be formed with a simple structure.

With reference to FIG. 5 and FIG. 6, the accelerated running noise test performed with respect to the soundproof cover 30 mentioned above is demonstrated.
As shown in FIG. 5, in the accelerated running noise test, 20 m from the entry point a located on the linear reference line L to the escape point b is set as the measurement section, and the intermediate point between the entry point a and the escape point b. A microphone was installed at a height of 1.2 m above the ground at a measurement point d that was 7.5 m away from c to the side of the reference line L. The target vehicle traveling at a predetermined speed was entered from the entry point a, and the noise level when the vehicle was driven along the reference line L to the escape point b was measured with a microphone.

  FIG. 6 shows an example of the result of the accelerated running noise test. The test result shown in FIG. 6 shows the worst case of the noise level measured on the side frame 12R side. In FIG. 6, the embodiment shown by the dotted line shows the test result of the vehicle with the soundproof cover 30 attached, and the comparative example shown by the solid line shows the test result of the vehicle attached with the conventional soundproof cover that covers the engine 15 from below the vehicle. Show. The vehicle used in the test is the same vehicle in both the example and the comparative example.

  As shown in FIG. 6, it was recognized that the noise level of the example is equivalent to that of the comparative example. That is, although the soundproof cover 30 of the example has a simpler structure than the soundproof cover of the comparative example, it was recognized that the noise outside the vehicle was reduced at the same level as the soundproof cover of the comparative example.

According to the outside noise reduction structure of the above embodiment, the following effects can be obtained.
(1) The soundproof cover 30 is disposed in a space outside the vehicle 10 relative to the side frame 12 </ b> R, and overlaps the oil pan 17 and the flexible pipe 21 in the width direction of the vehicle 10. Thereby, the soundproof cover 30 for reducing the noise outside the vehicle can have a simple structure.

  (2) Since the soundproof cover 30 is not configured to cover the oil pan 17 from below the vehicle 10, it is unlikely to become an obstacle when performing various maintenance such as draining the engine oil or replacing the oil filter. That is, the above-described soundproof cover 30 does not significantly reduce the maintenance workability of the engine 15.

(3) Since the soundproof cover 30 is not configured to cover the oil pan 17 from below the vehicle 10, the heat dissipation of the oil pan 17 can be enhanced.
(4) The soundproof cover 30 has an offset wall portion 37 that offsets the rear wall portion 36 to the outside of the vehicle 10 with respect to the front wall portion 35. Such an offset wall 37 can increase the rigidity of the soundproof cover 30. Thereby, since the natural frequency of the soundproof cover 30 is increased, the soundproof cover 30 is less likely to resonate with the vibration of the vehicle 10.

  (5) In addition, the offset wall portion 37 is inclined so that the portion on the rear side of the vehicle 10 is positioned outside the vehicle 10. Therefore, an increase in air resistance due to such an offset wall portion 37 can be suppressed.

  (6) The soundproof cover 30 includes a lower end wall portion 38 that extends from the lower end edge of the second rear wall portion 52 toward the inside of the vehicle 10 on the noise generation source side with respect to the soundproof cover 30. Thereby, it is possible to reduce the diffracted sound that travels from the lower end of the soundproof cover 30 to the outside of the vehicle 10 and propagates to the side of the vehicle 10. As a result, noise outside the vehicle can be further reduced.

  (7) The offset wall portion 37 and the lower end wall portion 38 are connected by the connecting member 60. Thereby, the rigidity of the soundproof cover 30 can be further increased. As a result, the soundproof cover 30 is less likely to resonate with the vibration of the vehicle 10.

  (8) The soundproof cover 30 has a rear end wall portion 39 that extends from the rear end edge of the rear wall portion 36 toward the inside of the vehicle 10 on the noise generation source side with respect to the soundproof cover 30. As a result, it is possible to reduce the diffracted sound that travels from the rear end of the soundproof cover 30 to the outside of the vehicle 10 and propagates obliquely rearward of the vehicle 10. As a result, noise outside the vehicle can be further reduced. In addition, it is preferable that the angle between this rear end wall part 39 and the rear wall part 36 is an obtuse angle.

  (9) Since the soundproof cover 30 is covered with the sound absorbing materials 71 and 72, a part of the first region 73 and a part of the second region 74, Noise outside the vehicle due to the reflected sound reflected by a part of the second region 74 can be reduced. Further, since the inspection port 68 is formed in a region different from the first region 73 and the second region 74, it is possible to improve the workability of the inspection while suppressing an increase in vehicle exterior noise caused by the inspection port 68. it can.

  (10) The soundproof cover 30 includes a thick first constituent member 40 to which the various brackets 31 to 33 are connected, and a thin second constituent member 50 that overlaps the oil pan 17 and the flexible pipe 21 in the width direction of the vehicle 10. It is constituted by. Thereby, since the soundproof cover 30 is composed of a plurality of members having different natural frequencies, the soundproof cover 30 is further less likely to resonate with respect to the vibration of the vehicle 10. Moreover, the weight of the soundproof cover 30 can be reduced while increasing the mechanical strength of the portion to which the brackets 31 to 33 are connected.

  (11) The soundproof cover 30 is connected to the side frame 12R via the brackets 31 to 33. Therefore, the soundproof cover 30 can be applied to a plurality of types of vehicles by changing the shapes of the brackets 31 to 33.

  (12) In the soundproof cover 30, the rear wall 36 is offset from the front wall 35 to the outside of the vehicle 10. It is located far away. Therefore, a mechanical load larger than that of the fastening portions of the front brackets 31 and 32 acts on the fastening portion of the rear bracket 33 along with the vibration of the vehicle. In this regard, in the soundproof cover 30, the fastening portion of the rear bracket 33 is reinforced by the first reinforcing plate 65. Thereby, the mechanical load which acts on the fastening part of the rear side bracket 33 can be disperse | distributed effectively.

  (13) In the soundproof cover 30, sound absorbing materials 71 and 72 that cover a part of the first region 73 and a part of the second region 74 are attached to the inside of the vehicle 10. Thereby, the vibration of the soundproof cover 30 based on the noise emitted from the oil pan 17 and the flexible pipe 21 can be suppressed.

In addition, the said embodiment can also be suitably changed and implemented as follows.
In the soundproof cover 30, the front wall portion 35, the rear wall portion 36, and the offset wall portion 37 are not limited to the configuration formed by the first component member 40 and the second component member 50, and the lower end wall portion 38 and It may be formed of one member including the rear end wall portion 39.

  -The lower end wall part 38 should just have the wall part extended inside the vehicle 10 from the lower end edge of the 2nd rear wall part 52, and the angle between the 2nd rear wall parts 52 becomes an obtuse angle. It is not restricted to what inclines with respect to the 2nd rear wall part 52. FIG. For example, the lower end wall portion 38 may have a flange shape having a lower end inward wall extending from the lower end edge of the second rear wall portion 52 to the inside of the vehicle 10 and a lower end outward wall extending toward the outside of the vehicle 10. Good.

  The rear end wall portion 39 only needs to have a wall portion that extends from the rear end edge of the second rear wall portion 52 to the inside of the vehicle 10. Therefore, the rear end wall portion 39 has, for example, a flange shape having a rear end inward wall extending from the rear end edge of the second rear wall portion 52 to the inside of the vehicle 10 and a rear end outward wall extending toward the outside of the vehicle 10. You may have.

  The soundproof cover 30 only needs to have a configuration that overlaps the oil pan 17 and the flexible pipe 21 below the side frame 12R in the width direction of the vehicle 10. Therefore, the soundproof cover 30 may have a configuration in which at least one of the rear end wall portion 39 and the lower end wall portion 38 is omitted. Further, the soundproof cover 30 may have a configuration in which the connecting member 60 is omitted. The soundproof cover 30 may have a front lower end wall portion that extends from the lower end edge of the front wall portion 35 toward the inside of the vehicle 10, and extends from the front end edge of the front wall portion 35 toward the inside of the vehicle 10. It may have a front end wall portion extending in the direction.

The offset wall portion 37 may be configured to offset the rear wall portion 36 to the inside of the vehicle 10 with respect to the front wall portion 35.
The soundproof cover 30 is not limited to the configuration in which the rear wall portion 36 is offset with respect to the front wall portion 35, and may have, for example, a flat plate shape. Further, the soundproof cover 30 is not limited to a metal member, and may be formed of a resin member. In such a configuration, the lower end wall portion 38 extends from the lower end edge of the soundproof cover 30 to the inside of the vehicle 10, and the rear end wall portion 39 extends from the rear end edge of the soundproof cover 30 to the inside of the vehicle 10.

The soundproof cover 30 may be attached not only to the side frame 12R but also to the opposite side frame 12.
The soundproof cover 30 may have a configuration in which at least one of the first reinforcing plate 65, the inspection port 68, and the sound absorbing materials 71 and 72 is omitted. Moreover, the inspection port 68 should just be formed in the area | region different from the 1st area | region 73 and the 2nd area | region 74, for example, may be formed in the offset wall part 37. FIG. The soundproof cover 30 may have one or more sound absorbing materials, and the sound absorbing material may cover only a part of the first region 73 or may cover only a part of the second region 74. There may be.

-The 1st component member 40 and the 2nd component member 50 are not restricted to the structure joined by welding, For example, the structure fastened by a fastening member may be sufficient.
The soundproof cover 30 is not limited to the configuration connected to the side frame 12R via the brackets 31, 32, 33, and may be directly connected to the side frame 12R.

Next, a technical idea grasped from the above-described embodiment will be added.
(Appendix 1)
The offset wall portion offsets the rear wall portion to the outside of the vehicle with respect to the front wall portion, and the soundproof cover is a connecting wall portion that connects the lower end wall portion and the offset wall portion. The exterior noise reduction structure according to claim 3.
According to the above configuration, the rigidity of the soundproof cover can be further increased. As a result, the soundproof cover is less likely to resonate with respect to vehicle vibration.

  DESCRIPTION OF SYMBOLS 10 ... Vehicle, 12 and 12R ... Side frame, 15 ... Engine, 16 ... Bottom part forming member, 17 ... Oil pan, 20 ... Exhaust passage, 21 ... Flexible pipe, 23 ... Leaf spring, 24 ... Spring bracket, 25 ... Shackle, 26 ... Front tire, 30 ... Soundproof cover, 31, 32 ... Front bracket, 33 ... Rear bracket, 35 ... Front wall, 36 ... Rear wall, 37 ... Offset wall, 38 ... Lower end wall, 39 ... Rear End wall part 40 ... first component member 41 ... first front wall part 42 ... first rear wall part 43 ... first offset wall part 44 ... first rear end wall part 45,46 ... front side fastening Holes, 47, 48 ... rear side fastening holes, 50 ... second constituent member, 51 ... second front wall part, 52 ... second rear wall part, 53 ... second offset wall part, 54 ... second rear end wall part 55 ... Lower inclined wall, 56 ... Bending piece, 6 ... connecting member, 60F ... front side joining part, 60R ... rear side joining part, 65 ... first reinforcing plate, 68 ... inspection port, 71 ... front side sound absorbing material, 72 ... rear side sound absorbing material, 73 ... first region, 74 ... Second area.

Claims (6)

A pair of left and right side frames;
An engine located between the pair of left and right side frames;
A flexible pipe that is located between the engine and one of the pair of left and right side frames, and that forms a part of the exhaust passage of the engine and absorbs vibrations transmitted through the exhaust passage;
A soundproof cover for reducing outside noise caused by driving of the engine,
The soundproof cover extends in the front-rear direction of the vehicle on the outside of the vehicle with respect to the one side frame, and the one side with respect to the oil pan and the flexible pipe of the engine in the width direction of the vehicle. External noise reduction structure that overlaps under the frame. The soundproof cover includes a front wall portion, a rear wall portion located on the rear side of the vehicle with respect to the front wall portion, and the front wall portion and the rear wall portion. The vehicle exterior noise reduction structure according to claim 1, further comprising an offset wall portion that offsets the wall portion in a width direction of the vehicle. The exterior noise reduction structure according to claim 2, wherein the soundproof cover has a lower end wall portion that extends from a lower end edge of the rear wall portion to the inside of the vehicle. The exterior noise reduction structure according to claim 2, wherein the soundproof cover has a rear end wall portion that extends from a rear end edge of the rear wall portion to the inside of the vehicle. The soundproof cover is
A first region facing the oil pan in the width direction of the vehicle;
A second region facing the flexible pipe in the width direction of the vehicle;
An inspection port formed in a region different from the first region and the second region;
The vehicle exterior noise reduction according to any one of claims 1 to 4, further comprising: a sound absorbing material attached to a surface facing the inside of the vehicle and covering at least a part of the first region or at least a part of the second region. Construction. The soundproof cover is
A thick member connected to the one side frame via a bracket;
The exterior noise reduction structure according to any one of claims 1 to 5, further comprising as a constituent member a thin member that is connected to the thick member and overlaps the oil pan and the flexible pipe in a width direction of the vehicle.