JP2018083511A - Front sub frame structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain engine sound from propagating from an engine room to a passenger compartment.SOLUTION: A front sub frame structure extends in a vehicle width direction behind an engine 1, and supports a lower arms 27 each arranged in a suspension of a front wheel F. The front sub frame structure is provided with an acoustic absorbent 40 along an upper surface 24a of a suspension-cross-member below an exhaust tube 13 extending from the engine 1 to a tunnel part 11 behind the engine. The acoustic absorbent 40 comprises: an acoustic absorbent main body part 41 and a fitting leg part 42 attached to a sub frame 20. The acoustic absorbent 40 is disposed above away from the upper surface 24a of the suspension-cross-member, owing to the fitting leg part 42 protruding downward from the acoustic absorbent main body part 41.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a front subframe structure for a vehicle including a front suspension cross member that supports a suspension of a front wheel.

  When noise emitted from the engine mounted in the engine room configured in the front of the vehicle propagates from the engine room to the vehicle interior, the comfort of passengers (especially drivers) in the vehicle interior is impaired. It is preferable to take a soundproofing measure so as not to propagate to the passenger compartment other than the minimum volume that the occupant can grasp.

  Therefore, the dash panel that separates the engine room from the vehicle compartment, the hood, and sound-insulating materials such as sound-absorbing materials are arranged on the sides of the engine, and the undercover is formed with its own sound-absorbing effect. Covering is conventionally performed.

  For example, the engine-encapsulated structure of a vehicle disclosed in Patent Document 1 is a countermeasure that encapsulates the engine, that is, covers almost the entire circumference of the engine with a cover so that engine noise does not flow into the vehicle interior.

  The engine-encapsulated structure for a vehicle of Patent Document 1 includes an upper cover (111) for shielding the upper side of the engine room, left and right side covers (112) for shielding both left and right sides, and a rear cover for shielding the rear face. (113) and an underbody encapsulating member (120) disposed at the lower part of the engine room, and further on the front side of the engine room. Is an air flap that opens and closes the front inlet.

  However, in general, a space for passing an exhaust pipe and a propeller shaft from the engine to the rear of the vehicle body extends from the engine to the tunnel portion at the rear of the engine room. Even in a configuration in which a member having a soundproof function is arranged around the vehicle, an engine sound intrusion path from the floor panel to the vehicle interior remains.

  In particular, in the case of a configuration that covers the periphery of the engine as in Patent Document 1, the engine sound may leak into the floor tunnel portion intensively through the space extending to the floor tunnel, and may be propagated as noise to the vehicle interior. There was also.

  And, for example, a sub-frame to which a lower arm provided in a front wheel suspension device is attached, like a vehicle adopting a so-called front engine-front drive system (FF system) in which an engine is mounted on the front part of a vehicle to drive a front wheel. In the structure provided, even if the undercover has a sound absorbing function like the underbody encapsulating member (120) of Patent Document 1, it is reflected by the subframe which is a highly rigid member positioned above the undercover. There was a problem that the engine sound to be attenuated by the undercover was difficult to attenuate, and there was room for improvement.

  In addition, because the subframe is equipped with many auxiliary equipment such as a steering gear case and stabilizer, it is difficult to arrange the sound absorbing material, and even if the sound absorbing material is simply arranged on the subframe, mud and snow melting agent remain on the sound absorbing material. However, there is a risk of rust prevention because it tends to be a moist environment.

JP 2013-119384 A

  Therefore, an object of the present invention is to suppress the propagation of engine sound from the engine room to the passenger compartment.

  The present invention is a front subframe structure that extends in the vehicle width direction behind the engine and supports a suspension of a front wheel, and is configured to absorb sound along the upper surface of the subframe below an exhaust pipe that extends from the engine to a rear tunnel portion. The sound absorbing material includes a sound absorbing material main body portion and a subframe mounting portion to be attached to the subframe. The sound absorbing material has the subframe mounting portion downward with respect to the sound absorbing material main body portion. By being protruded, it is spaced apart from the upper surface of the subframe.

  According to the above configuration, the engine sound (powertrain sound) on the upper surface of the subframe is prevented from reverberating and resonating with the tunnel, improving the soundproofing performance, and mud and snow melting agent between the sound absorbing material and the upper surface. It is possible to simultaneously prevent the occurrence of rust caused by remaining.

  As an aspect of the present invention, a steering gear unit is spaced above the upper surface of the sub-frame and extends in the vehicle width direction, and the sound absorbing material is disposed below the steering gear unit. It is preferable that the peripheral part of the lower part is thicker than the lower part of the gear unit.

  According to the above configuration, by increasing the thickness of the peripheral part of the lower part compared to the lower part of the steering gear unit, the uneven shape can be increased together with the steering gear unit above the subframe. Excellent diffusibility can be obtained so that engine sound does not propagate backward.

  Furthermore, according to the above configuration, it is possible to reduce the size of the soundproofing material by thinning the portion overlapping with the steering gear unit having high rigidity (high natural frequency).

  As an aspect of the present invention, a power train including the engine is covered with a heat insulating soundproof material from at least above and behind, and above a cross member extending in the vehicle width direction behind the power train. In addition, a space through which the exhaust pipe passes rearward is provided.

  According to the said structure, while being able to improve the warm air and air resistance by the heat management of a power train, the sealing property of the power train as a sound source can be improved with a sound absorbing material.

  As the heat insulating soundproofing material, for example, at least one of a sound absorbing material formed in a nonwoven fabric shape or a porous shape and a sound insulating material formed of resin, aluminum, or the like can be used.

  According to this invention, propagation of engine sound from the engine room to the passenger compartment can be suppressed.

The longitudinal cross-sectional view which shows the principal part of the vehicle front part provided with the front sub-frame of this embodiment. The top view of the front sub-frame of this embodiment provided with the sound insulation member. FIG. 3 is a perspective cross-sectional view of the vicinity of a suspension cross viewed from the upper front side with respect to the line AA in FIG. 2. FIG. 3 is an essential part cross-sectional view taken along line AA in FIG. 2. Sectional drawing of the principal part of the BB line in FIG. Sectional drawing of the principal part of the CC line | wire in FIG. The perspective view which looked at the sound insulation member from the upper part. The perspective view which looked at the sound insulation member from the lower part. The front view and left view of a sound insulation member. The top view and bottom view of a sound insulation member.

An embodiment of the present invention will be described below with reference to the drawings.
First, the first embodiment will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view of a front portion of a vehicle in which the front subframe of the present embodiment is adopted, and is a vertical cross-sectional view partially showing a main portion of a vehicle width direction central portion of the front portion of the vehicle Is a plan view of the front sub-frame of the present embodiment provided with a sound insulation member, FIG. 3 is a perspective cross-sectional view of the periphery of the suspension cross viewed from the upper front side with respect to the line AA in FIG. 2, and FIG. FIG. 5 is a sectional view showing the end surface of the BB line in FIG. 2, FIG. 6 is a sectional view showing the end surface of the CC line in FIG. 2, and FIG. FIG. 8 is a perspective view of the sound insulation member as viewed from below, FIG. 9 (a) is a front view of the sound insulation member, FIG. 9 (b) is a left side view of the sound insulation member, and FIG. (A) is a top view of a sound insulation member, FIG.10 (b) is a bottom view of a sound insulation member. In FIG. 1, the engine is schematically shown for convenience. In the following description, in the drawings, arrow F indicates the front of the vehicle, arrow R indicates the right side of the vehicle, arrow L indicates the left side of the vehicle, and arrow U indicates the upper side of the vehicle.

  The vehicle V of the present embodiment employs a so-called front engine front drive system (FF system) in which the engine 1 which is an internal combustion engine is mounted on the front portion of the vehicle V and drives the front wheels F, as shown in FIG. In the front part of the vehicle V according to the present embodiment, an engine room E for accommodating a power train PT including the engine 1 and a transmission (not shown) is provided. In the engine room E, the front side of the vehicle V is partitioned by a front grill 2, a front bumper 3, and a shroud panel 4, and the rear side of the vehicle V is partitioned by a dash panel 5 and a cowl panel 6 that extend in the vertical direction.

  Further, the engine room E is partitioned from the outside by a hood 7 that extends horizontally in the upper part of the vehicle and an under cover 8 that also extends in the horizontal direction in the lower part of the vehicle. Further, the side of the engine room E is partitioned by a wheel house and a wheel apron that cover the front wheel F although not shown.

  The under cover 8 is formed in a flat plate shape, and as shown in FIG. 1, the front end portion is fixed to the lower end portion of the front bumper 3 with screws B1 and the like, and the middle portion in the front-rear direction is attached to the front cross member 22 described later. The rear portion is fixed to the center cross member 23 and the rear end is fixed to the suspension cross 24 with screws B1 or the like, so that the rear portion is disposed below the engine room E.

  By mounting the under cover 8 below the engine room E, it is possible to prevent the traveling wind flowing below the vehicle V from flowing into the engine room E when the vehicle is traveling and to improve the aerodynamic characteristics below the vehicle V. Thus, it functions as a sound insulating material that prevents engine sound from leaking from below the vehicle V.

  The dash panel 5 is formed in the vehicle width direction so as to partition the engine room E and the vehicle compartment C in the front-rear direction. That is, a front space separated from the vehicle compartment C by the dash panel 5 is set in the engine room E.

  A floor panel 9 is bonded and fixed to the lower rear end of the dash panel 5. The floor panel 9 extends substantially horizontally toward the rear and constitutes the bottom surface of the passenger compartment C. The floor panel 9 protrudes toward the passenger compartment C at the center in the vehicle width direction of the floor panel 9 and extends in the front-rear direction. A floor tunnel 11 (hereinafter referred to as “tunnel portion 11”) extending to the floor panel 9 is integrally formed with the floor panel 9.

  As shown in FIG. 1, the exhaust system of the engine 1 employs a so-called rear exhaust layout in which an exhaust manifold 12 and a catalyst 14 for reducing NOx are disposed on the rear side of the vehicle V.

  Specifically, an exhaust manifold 12 is connected to a cylinder head of the engine 1 mounted in the engine room E via an exhaust port (not shown), and exhaust gas from the engine 1 is connected to the exhaust manifold 12. An exhaust pipe 13 leading to an exhaust silencer (not shown) at the rear of the vehicle V is connected. The exhaust pipe 13 is disposed in the tunnel portion 11 and extends toward the rear of the vehicle V. The catalyst 14 is provided on the downstream side of the connection portion with the exhaust manifold 12 in the exhaust pipe 13.

  A top cover 15 as an engine cover is disposed above the engine room E and below the bonnet 7. The top cover 15 is a heat insulating soundproof material extending in the front-rear direction from the upper end of the shroud panel 4 to the front end of the cowl panel 6 so as to cover substantially the entire engine 1 from above. The top cover 15 is not limited to the configuration provided as the engine cover on the engine room E side of the vehicle V, and may be configured to be attached to the back surface of the bonnet 7.

  Further, a rear cover 16 is disposed behind the engine room E and on the front side of the dash panel 5 so as to extend downward from the rear portion of the top cover 15. The rear cover 16 is a heat insulating soundproof material that extends rearward so as to close a gap in the front-rear direction between the top cover 15 and the cowl panel 6 and extends downward so as to hang down from the rear end. Both the top cover 15 and the rear cover 16 are formed of a heat-resistant member such as ABS resin so as to have a sound insulation function (sound insulation function) in addition to a heat insulation function.

The center portion of the rear cover 16 in the vehicle width direction extends downward to a position before the rear lower end of the rear cover 16 interferes with the exhaust pipe 13, that is, to a position spaced apart from the exhaust pipe 13.
As described above, the engine room E includes the top cover 15 disposed above, the under cover 8 disposed below, the shroud panel 4 disposed on the front, the rear cover 16 disposed on the rear, and left and right (not shown) disposed on the sides. A wheel house, a wheel apron, and the like cover substantially the entire circumference, and these covers (panels) contribute to preventing the noise of the engine 1 from propagating to the outside, particularly to the passenger compartment C.

  However, as shown in FIG. 1, the space 17 (the engine room E and the tunnel portion 11 communicate with each other below the center of the rear cover 16 in the vehicle width direction, that is, behind the engine room E and in the center of the vehicle width direction. The exhaust pipe 13 extends from the engine room E to the tunnel portion 11 through the space 17. That is, since the engine sound propagates from the engine room E to the tunnel portion 11 through the space 17, an intrusion path of the engine sound from the floor panel 9 into the vehicle compartment C remains behind the engine room E.

  As shown in FIG. 1, a front subframe 20 (hereinafter referred to as “subframe 20”) to which a lower arm of a front wheel suspension device is attached is located behind and above the undercover 8 in the engine room E, that is, below the space 17. Is provided).

  As shown in FIG. 2, the subframe 20 includes a suspension cross member 24 (hereinafter referred to as “suspension cross 24”) as a main body of the subframe 20 that connects a pair of left and right front and rear members 21 and 21 and a rear end of the front and rear member 21 in the vehicle width direction. And a front cross member 22 that connects the front portions of the front and rear members 21 in the vehicle width direction, and is configured as a so-called perimeter formed in a substantially quadrilateral frame shape in plan view. The subframe 20 is attached to a front side frame (not shown) located above via a connecting portion (not shown).

  The front and rear members 21 and the suspension cloth 24 are each formed in a hollow shape by joining an upper panel 20u that constitutes an upper surface and a lower panel 20d that constitutes a lower surface. Among these members, the front / rear member 21 is formed of a cylindrical body having a closed cross section extending in the front / rear direction of the vehicle V.

  Reference numeral 25 in FIG. 2 is an extension frame (sub-crash can) extending from the front end of the front and rear members 21 to the front of the vehicle V via a plate-like flange, and reference numeral 26 is a connection of the front end of the extension frame in the vehicle width direction. Reference numeral 23 denotes a center cross member extending in the vehicle width direction behind the front cross member 22 and in front of the suspension cross 24. In FIG. 1, the sub-bumper beam 26 is not shown.

  As shown in FIGS. 1 to 3, a steering gear unit 30 serving as an auxiliary device that transmits an operation amount of a steering wheel (not shown) to the left and right front wheels F is provided above the subframe 20. Is a steering rack 31 (see FIGS. 1 and 3) extending in the vehicle width direction at a position spaced upward with respect to the suspension cross 24 in the subframe 20, and a pinion 32 (gear box) linked to the steering rack 31 ( 2 and FIG. 3). As shown in FIG. 5, the steering rack 31 is fastened and fixed to the suspension cross upper surface 24a by using bolts B5 and the like via attachment members 33 that extend downward on the left and right sides in the vehicle width direction. The pinion 32 is linked to a steering wheel (not shown) via a steering shaft (not shown).

  Above the sub-frame 20, there are provided only one wheel bump by resistance of torsional rigidity, and a stabilizer 35 (also referred to as a torsion beam) known as an auxiliary machine that suppresses the roll angle when rebounding. An intermediate portion 35 a corresponding to the suspension cross 24 in the vehicle width direction of the stabilizer 35 extends horizontally in the vehicle width direction in parallel with the steering rack 31 at the same height as that of the steering rack 31. As shown in FIG. 2, the left and right ends of the vehicle width direction intermediate portion 35a of the stabilizer 35 are fastened and fixed to the upper surface 24a of the suspension cross 24 by means of bolts B6 or the like via a mounting bracket 37.

  As shown in FIGS. 1 to 5, the sub-frame 20 is provided with a sound absorbing material 40 along the upper surface 24 a of the suspension cloth 24 extending in the vehicle width direction.

  As shown in FIGS. 7 to 9A, 10B, 10A, and 10B, the sound absorbing material 40 includes a sound absorbing material main body 41 and mounting legs 42 attached to the upper surface 24a of the suspension cloth 24. And is formed. In this example, the sound absorbing material 40 includes four mounting legs 42 (42a, 42b, 42c, 42d). Specifically, the sound absorbing material 40 includes a front left mounting leg portion 42a formed on the front side and the left end, a front right mounting leg portion 42b formed on the front side and the right end, and a rear side formed on the left end. It includes a left mounting leg portion 42c and a rear right mounting leg portion 42d formed on the rear side and the right side.

  Of these four mounting legs 42, the rear left mounting leg 42c includes an extended portion 43 extending downward from the sound absorbing material main body 41 and a flat flange portion having an insertion hole 44a formed through the central portion. 44 is formed in a substantially L shape in a longitudinal sectional view.

  Of the four attachment legs 42, the front left attachment leg 42a, the front right attachment leg 42b, and the rear right attachment leg 42d are all stepped first extensions extending downward from the sound absorbing material main body 41. A protruding portion 43a (see FIG. 10A), a flat extending portion 43b extending in a flat shape substantially parallel to the sound absorbing material main body 41, and a second extending downward from the flat extending portion 43b. The extending portion 43c is formed by a flat flange portion 44 having an insertion hole 44a (see FIG. 7) formed through the center portion.

That is, in each of these three attachment legs 42a, 42b, 42d, the flat extension 43b is located in the middle between the sound absorbing material main body 41 and the flange 44 in the vertical direction, and the sound absorbing material main body 41 has a flange. The first extending portion 43a and the second extending portion 43c extend downward in two stages through the flat extending portion 43b until reaching the portion 44.
In other words, each of these three mounting legs 42a, 42b, 42d is arranged in the order of the sound absorbing material main body 41, the flat extension 43b, and the flange 44 in FIG. 8 when the sound absorbing material 40 is viewed from the bottom side. It is arrange | positioned so that it may be located below (from the back side of the paper surface of FIG. 8). That is, the first extending portion 43a is formed in a vertical wall shape (step shape) rising from the sound absorbing material main body portion 41 toward the flat extending portion 43b toward the front side of the sheet of FIG. The extending portion 43c is formed in a vertical wall shape (step shape) rising from the flat extending portion 43b toward the flange portion 44 in the bottom view as viewed from the front side of FIG.

  Of these four mounting legs 42 (42a, 42b, 42c, 42d), the front left mounting leg 42a is positioned at the front and left side of the upper surface 24a of the suspension cloth 24 (see FIGS. 2 and 6). The right mounting leg portion 42b is at the front and right side position of the upper surface 24a of the suspension cloth 24 (see FIG. 3), and the rear left mounting leg portion 42c is at the rear and left side position of the upper surface 24a of the suspension cloth 24 (see FIG. The rear right mounting leg portion 42d is attached to the rear and right side positions of the upper surface 24a of the suspension cloth 24 (see FIGS. 2 and 6) using fasteners B2 and the like that are inserted through the insertion holes 44a, respectively. ing.

  As described above, the sound-absorbing material 40 has at least the sound-absorbing material main body 41 as the suspension cloth 24 in a state where the four attachment legs 42 are attached to the upper surface 24a of the suspension cloth 24, as shown in FIGS. On the other hand, it can be arranged in a state of being separated upward, that is, in a floating state, and a vertical gap S can be ensured between the lower surface of the sound-absorbing material main body 41 and the upper surface 24a of the suspension cloth 24.

  Specifically, the sound absorbing material 40 is in a state in which only the flange portions 44 of the four attachment leg portions 42 are installed on the upper surface 24a of the suspension cloth 24, and all of the sound absorbing material 40 other than the flange portion 44 including the sound absorbing material main body portion 41 are included. The parts are arranged in a state of being separated upward from the upper surface 24 a of the suspension cloth 24.

  As shown in FIGS. 1, 2 to 9A, 9B, the above-described sound absorbing material 40 is integrally formed in a state in which two panels of a sound absorbing panel 45 and a base panel 46 are overlapped. Has been. The sound absorbing panel 45 and the base panel 46 are formed in substantially the same shape in plan view.

  The sound absorbing panel 45 is formed by integral molding with a porous member, in this example, a urethane member, and the base panel 46 is formed with higher rigidity than the sound absorbing panel 45 by a metal plate such as stainless steel or aluminum. ing. As long as the base panel 46 is a member that can support the sound absorbing panel 45 from the lower side, the base panel 46 is not limited to a metal such as stainless steel or aluminum as in this example. Etc. can be formed.

As shown in FIG. 2, the sound absorbing material 40 is arranged in a state of overlapping (overlapping) the steering gear unit 30 and the stabilizer 35 in plan view.
In other words, the steering rack 31 and the stabilizer 35 are both disposed so as to straddle the sound absorbing material 40 in the vehicle width direction. On the other hand, the sound absorbing material 40 is disposed so as to straddle the steering rack 31, the stabilizer 35, and the vehicle V longitudinal direction.

  Of the mounting legs 42 described above, the front right mounting leg 42b, the rear left mounting leg 42c, and the rear right mounting leg 42d are the steering gear unit 30 and the steering gear 30 as auxiliary devices provided above the suspension cross 24. It is formed so as to avoid the rack 31.

  Specifically, among the mounting legs 42, the flange portion 44 of the front right mounting leg 42b is formed so as to enter under the pinion 32 provided in the steering gear unit 30 as an auxiliary machine. As a result, the front right mounting leg portion 42b is located immediately below the pinion 32 and provided at a position overlapping the pinion 32 in plan view (see FIG. 2), but is arranged so as not to interfere with the pinion 32 in the vertical direction. Has been.

  Further, as shown in FIGS. 2, 5, and 6, among the mounting legs 42, the flanges 44 of the rear left mounting leg 42c and the rear right mounting leg 42d are below the stabilizer 35 as an auxiliary machine. It is formed so that it may enter especially. Thus, the rear left mounting leg 42c is provided at a position overlapping the vehicle width direction intermediate part 35a of the stabilizer 35 in plan view (see FIG. 2), and the rear right mounting leg 42d is Although it is provided at a position close to the vehicle width direction intermediate portion 35a in plan view (see the figure), both are arranged so as not to interfere with the stabilizer 35 in the vertical direction.

Further, as shown in FIGS. 7, 8, 9 (a), 10 (a) and 10 (b), the sound absorbing material 40 includes a steering gear unit 30 as an auxiliary machine provided above the suspension cross 24. Escape portions (51, 52, 53, 54) are formed so as to avoid the above.
Specifically, as shown in FIG. 3 and FIG. 4, the sound absorbing material 40 has a downward concave shape that is formed as a relief portion in a concave shape in a portion corresponding to the steering rack 31 in a plan view in the sound absorbing material main body 41. 2 and 5, the left side formed corresponding to the left side mounting member 33 among the left side and right side mounting members 33, 33 to the suspension cross upper surface 24a of the steering rack 31, as shown in FIGS. As shown in FIGS. 6 and 7, the opening 52, the right groove 53 formed corresponding to the pinion 32 provided in the steering gear unit 30, and the rear groove formed corresponding to the propeller shaft (not shown). 54.

  As shown in FIGS. 3, 7, and 8, the lower concave portion 51 connects the first extending portion 43 a and the left opening 52 in the vehicle width direction so as to surround the substantially lower half of the steering rack 31. The sound absorbing material 40 is formed in an intermediate portion in the front-rear direction of the sound absorbing material main body 41 in a substantially semicircular concave shape in the cross-sectional view along the vehicle width direction.

  As shown in FIG. 7, the left opening 52 is formed by penetrating the boundary portion of the sound absorbing material main body 41, the front left mounting leg 42 a and the rear left mounting leg 42 c and its peripheral portion in the thickness direction. is there. The right groove 53 is formed such that the boundary between the front right mounting leg 42b and the rear right mounting leg 42d and its peripheral part are cut out in the vehicle width direction from the right end (see the same figure). The rear groove portion 54 is formed by notching the intermediate portion in the vehicle width direction of the sound-absorbing material main body portion 41 from the rear end to the front (see the same figure).

As shown in FIG. 7, the sound absorbing material 40 is formed with raised portions 55 (55 a, 55 b, 55 c) that protrude above the upper surface of the sound absorbing material main body 41.
The raised portion 55 is formed by thickening a part of the sound absorbing panel 45, and the inside thereof is made solid by urethane forming the sound absorbing panel 45. The raised portion 55 is formed so as to be at least partially adjacent to the lower concave portion 51. Specifically, as shown in FIG. 3 and FIG. 7, the front side of the lower concave portion 51 in the sound absorbing material main body 41 is provided. And a front raised portion 55a extending along the front edge of the lower concave portion 51 at a position on the right side of the vehicle V, and a rear groove portion on the rear side of the lower concave portion 51 of the sound-absorbing material main body portion 41 as shown in FIG. As shown in FIG. 7, it is formed at a position on the rear side of the lower concave portion 51 of the sound absorbing material main body 41 and on the left side of the rear groove portion 54, as shown in FIG. And a left rear raised portion 55c.

  The above-described front subframe 20 of the present embodiment has a front subframe structure that extends in the vehicle width direction behind the engine 1 and supports a lower arm 27 provided in a suspension (not shown) of the front wheel F (see FIGS. 1 and 2). 2) A sound absorbing material 40 is provided along the suspension cross upper surface 24a below the exhaust pipe 13 extending from the engine 1 to the rear tunnel portion 11 (see FIGS. 1 and 2). 41 and a mounting leg portion 42 as a subframe mounting portion to be attached to the subframe 20 (see in particular FIG. 7), and the sound absorbing material 40 has a mounting leg portion 42 projecting downward with respect to the sound absorbing material main body portion 41. As a result, it is disposed away from the suspension cross upper surface 24a (see FIGS. 1 and 3 to 6).

  According to the above configuration, the engine sound (powertrain PT sound) on the suspension cross upper surface 24a is prevented from reverberating and resonating to the tunnel portion 11 to improve the soundproof performance, and between the sound absorbing material 40 and the suspension cross upper surface 24a. It is possible to achieve both prevention of rust due to mud and snow melting agent residue.

  Specifically, the suspension cloth 24 provided in the sub-frame 20 extending in the vehicle width direction has a substantially flat wide upper surface 24a. Conventionally, the engine sound is reflected on the upper surface 24a of the suspension cloth so that the tunnel portion 11 It was easy to propagate backwards. Since the sub-frame 20 is positioned above the under cover 8 (see FIG. 1), the engine sound reflection on the upper surface 24a of the suspension cloth is an insulator (soundproof material) (not shown) on the upper surface of the under cover 8 as in the prior art. Even if it was provided, it could not be prevented.

  On the other hand, in the sub-frame 20 of the present embodiment, the sound absorbing material 40 is provided on the upper surface 24a of the suspension cloth 24, so that the engine sound (power train PT sound) on the suspension cloth upper surface 24a is prevented from reverberating and resonating. Soundproof performance can be improved.

  However, even if a sound absorbing material is simply provided on the upper surface 24a of the suspension cloth 24, if the suspension upper surface 24a is exposed to water, the sound absorption panel having excellent water absorption due to the porous structure absorbs water, so that the water absorption state is maintained for a long time. Is not preferable from the viewpoint of securing the rust prevention property of the suspension cloth 24. Particularly in cold regions, snow melting agents (freezing agents) such as sodium chloride and calcium chloride are often sprayed on the road, so that mud and snow melting agents remain between the sound absorbing material 40 and the upper surface 24a of the suspension cloth 24. There was a risk that the risk of rusting due to aging would become significant.

  Therefore, in the present embodiment, the sound absorbing material main body 41 of the sound absorbing material 40 is floated from the upper surface 24a of the suspension cloth 24 and then attached to the upper surface 24a of the suspension cloth 42 by the attachment legs 42, so that water, salt, mud, etc. are present on the suspension cloth upper surface 24a. Accumulation can be prevented, and the rust prevention property of the suspension cloth 24 can be enhanced. It is possible to achieve both prevention of rust generation due to mud and snow melting agent remaining between the sound absorbing material 40 and the suspension cloth upper surface 24a.

  Furthermore, the sound absorbing material 40 includes a base panel 46 that is more rigid than the sound absorbing panel 45, so that water remaining on the upper surface 24 a of the suspension cloth 24 does not adhere to the sound absorbing material 40 through the gap S between the suspension cloth upper surface 24 a and the sound absorbing material 40. It can be kept at a predetermined height.

  Moreover, in the present embodiment, the mounting leg portion 42 that supports the sound absorbing material main body 41 in a state where it floats from the upper surface 24a of the suspension cloth 24 is arranged such that the front right mounting leg portion 42b enters under the pinion 32, for example. (See FIGS. 3 and 6), the rear left mounting leg portion 42c and the rear right mounting leg portion 42d are disposed so as to enter under the vehicle width direction intermediate portion 35a of the stabilizer 35 (see FIGS. 2, 5, and 6). ) Etc., for example, the mounting leg 42 and the auxiliary devices such as the pinion 32 and the stabilizer 35 are arranged so as to overlap with each other in a plan view, thereby ensuring compactness and not interfering with the auxiliary devices (32, 35). It is provided as follows.

  Furthermore, the sound absorbing material 40 of the present embodiment has a sound absorbing property by having a sound absorbing panel 45 on the entire upper surface of the base panel 46 including the mounting leg portion 42 as well as the sound absorbing material main body 41. To further prevent reflection of the engine sound to the rear, and depending on the location, a raised portion 55 (55a, 55b, 55c) is provided to increase the sound absorption of the engine sound. At the same time, diffusibility can be enhanced.

  As described above, the sound absorbing material 40 according to the present embodiment forms the left opening 52 as the opening and the right groove 53 and the rear groove 54 as the groove in a portion corresponding to the auxiliary equipment such as the steering gear unit 30 and the stabilizer 35. Since the mounting recess 42 is provided so as to form the lower concave portion 51 as the escape portion recessed downward, and to enter the auxiliary machinery (30, 35) as described above, the auxiliary machinery (30 , 35) and covering the upper surface 24a of the suspension cross 24 in a separated state while avoiding interference with the sound, the rearward transmission due to the reflection of the engine sound can be prevented (see FIGS. 3 to 6).

  Since the sound absorbing material 40 is provided on the upper surface 24a of the suspension cloth 24 as in the present embodiment, it is possible to prevent the engine sound from propagating to the tunnel portion 11, and therefore, for example, the engine sound propagated to the tunnel portion 11 Since the floor panel 20d9 does not need to be provided with a soundproof panel such as an insulator, unlike the conventional structure, the vehicle V can be reduced in weight and the vehicle can be reduced. The space of the chamber C can be secured.

  As an aspect of the present invention, the steering gear unit 30 is spaced above the upper surface 24a of the suspension cross 24 and extends in the vehicle width direction, and the sound absorbing material 40 is disposed below the steering gear unit 30, A raised portion 55 (55a, 55b, 55c) is provided as a configuration in which the peripheral portion of the lower concave portion 51 is thicker than the lower concave portion 51 as a lower portion than the steering gear unit 30 ( 1 to 6).

  According to the above configuration, excellent diffusibility can be obtained so that the engine sound does not propagate backward by increasing the uneven shape in cooperation with the steering gear unit 30 above the subframe 20.

  More specifically, for example, the steering rack 31 and the pinion 32 provided in the steering gear unit 30 have high rigidity and high natural frequency, so that they are difficult to resonate with engine sound. Furthermore, since the steering rack 31 has a substantially cylindrical shape extending in the vehicle width direction, it can be said that the outer peripheral surface of the steering rack 31 is less likely to reflect the engine sound to the rear than the flat surface, and the propagating ability of the engine sound to the rear is relatively low.

  In the present embodiment, the upper portion of the steering rack 31 is not covered with the sound absorbing material 40, and the sound absorbing material 40 is provided with a lower concave portion 51 as a relief portion below the steering gear unit 30 and a lower concave portion. A raised portion 55 thicker than the lower concave portion 51 is arranged in a peripheral portion of the lower portion 51.

  As a result, by providing the sound absorbing material 40 in a concavo-convex shape around the periphery of the steering gear unit 30 other than the upper part, the concavo-convex shape can be increased together with the steering rack 31 above the suspension cross 24 in the vehicle width direction. However, it is possible to obtain excellent sound diffusivity utilizing the diffusibility of the engine sound of the substantially circular steering rack 31.

  Further, according to the above configuration, the sound absorbing material 40 is formed by thinning the portion overlapping the highly rigid (high natural frequency) steering gear unit 30, that is, by forming the lower concave portion 51 in the portion corresponding to the steering rack 31. Since it can be made compact, it is possible to achieve both layout properties with auxiliary equipment such as the steering gear unit 30 above the suspension cross 24 while maintaining the sound absorption effect of the engine sound.

  Further, as an aspect of the present invention, the power train PT including the engine 1 is covered with a top cover 15 and a rear cover 16 as heat insulating soundproofing materials (sound absorbing materials or sound insulating materials) at least from above and behind, and A space 17 through which the exhaust pipe 13 passes rearward is provided above the suspension cloth 24 extending in the vehicle width direction behind the power train PT (see FIG. 1).

  According to the above configuration, it is possible to improve the warm air and air resistance by the thermal management of the power train PT, and improve the sealing performance of the power train PT as a sound source in combination with the sound absorbing material 40.

  The present invention is not limited only to the configuration of the above-described embodiment, and many embodiments can be obtained.

  For example, in the embodiment described above, the sound absorbing panel 45 is formed by integrally forming the sound absorbing material main body 41 and the mounting leg portion 42. However, the present invention is not limited to this embodiment. And a mounting leg member as a bracket formed of a separate member, and the mounting leg member is interposed between the upper surface 24a of the suspension cloth 24 and the sound absorbing material main body 41, so that the sound absorbing material main body 41 is attached by the mounting leg member. You may employ | adopt the structure supported in the state which floated with respect to the upper surface 24a of the suspension cloth 24. FIG.

  As the heat insulating and soundproofing material such as the top cover 15 and the rear cover 16, for example, at least one of a sound absorbing material formed in a porous shape and a sound insulating material formed of resin, aluminum, or the like can be used.

  Further, as in the present embodiment, the structure in which the sound absorbing material 40 is disposed on the upper surface 24a of the suspension cloth 24 may be applied to an electric vehicle or a fuel cell vehicle. When applied to an electric vehicle, it is possible to prevent the motor sound from propagating to the vehicle compartment C side. When applied to a fuel cell vehicle, the sound of a blower fan for sending air into the fuel cell is detected. Propagation to the side can be prevented.

DESCRIPTION OF SYMBOLS 1 ... Engine 11 ... Tunnel part 13 ... Exhaust pipe 15 ... Top cover (heat insulation soundproofing material)
16 ... Rear cover (heat insulation and soundproofing material)
20 ... Front subframe (front subframe structure)
24 ... Suspension (cross member)
24a: Suspension upper surface (subframe upper surface)
27: Lower arm 30 of the suspension ... Steering gear unit 40 ... Sound absorbing material 41 ... Sound absorbing material body 42 ... Mounting leg (subframe mounting)
51. Lower concave part (lower part than steering gear unit)
55 ... Bump (thickened peripheral part of the lower part)
55a ... Front side bulge (thickened peripheral part of the lower part)
55b ... Right rear bulge (thickened peripheral part of the lower part)
55c ... Left rear raised part (thickened peripheral part of the lower part)
PT ... Powertrain

  The present invention relates to a front subframe structure for a vehicle including a front suspension cross member that supports a suspension of a front wheel.

  When noise emitted from the engine mounted in the engine room configured in the front of the vehicle propagates from the engine room to the vehicle interior, the comfort of passengers (especially drivers) in the vehicle interior is impaired. It is preferable to take a soundproofing measure so as not to propagate to the passenger compartment other than the minimum volume that the occupant can grasp.

  Therefore, the dash panel that separates the engine room from the vehicle compartment, the hood, and sound-insulating materials such as sound-absorbing materials are arranged on the sides of the engine, and the undercover is formed with its own sound-absorbing effect. Covering is conventionally performed.

  For example, the engine-encapsulated structure of a vehicle disclosed in Patent Document 1 is a countermeasure that encapsulates the engine, that is, covers almost the entire circumference of the engine with a cover so that engine noise does not flow into the vehicle interior.

  The engine-encapsulated structure for a vehicle of Patent Document 1 includes an upper cover (111) for shielding the upper side of the engine room, left and right side covers (112) for shielding both left and right sides, and a rear cover for shielding the rear face. (113) and an underbody encapsulating member (120) disposed at the lower part of the engine room, and further on the front side of the engine room. Is an air flap that opens and closes the front inlet.

  However, in general, a space for passing an exhaust pipe and a propeller shaft from the engine to the rear of the vehicle body extends from the engine to the tunnel portion at the rear of the engine room. Even in a configuration in which a member having a soundproof function is arranged around the vehicle, an engine sound intrusion path from the floor panel to the vehicle interior remains.

  In particular, in the case of a configuration that covers the periphery of the engine as in Patent Document 1, the engine sound may leak into the floor tunnel portion intensively through the space extending to the floor tunnel, and may be propagated as noise to the vehicle interior. There was also.

  And, for example, a sub-frame to which a lower arm provided in a front wheel suspension device is attached, like a vehicle adopting a so-called front engine-front drive system (FF system) in which an engine is mounted on the front part of a vehicle to drive a front wheel. In the structure provided, even if the undercover has a sound absorbing function like the underbody encapsulating member (120) of Patent Document 1, it is reflected by the subframe which is a highly rigid member positioned above the undercover. There was a problem that the engine sound to be attenuated by the undercover was difficult to attenuate, and there was room for improvement.

  In addition, because the subframe is equipped with many auxiliary equipment such as a steering gear case and stabilizer, it is difficult to arrange the sound absorbing material, and even if the sound absorbing material is simply arranged on the subframe, mud and snow melting agent remain on the sound absorbing material. However, there is a risk of rust prevention because it tends to be a moist environment.

JP 2013-119384 A

  Therefore, an object of the present invention is to suppress the propagation of engine sound from the engine room to the passenger compartment.

The present invention is a front subframe structure that extends in the vehicle width direction behind the engine and supports a suspension of a front wheel, and is configured to absorb sound along the upper surface of the subframe below an exhaust pipe that extends from the engine to a rear tunnel portion. The sound absorbing material includes a sound absorbing material main body portion and a subframe mounting portion to be attached to the subframe. The sound absorbing material has the subframe mounting portion downward with respect to the sound absorbing material main body portion. By projecting, the sound-absorbing material main body is disposed away from the upper surface of the subframe , the steering gear unit is spaced above the upper surface of the subframe and extends in the vehicle width direction, sound absorbing material is disposed while avoiding interference with the steering gear unit spaced downward with respect to the steering gear unit, the sound-absorbing Are those near sites flanking compared to lower portion formed in a portion corresponding to the steering gear unit in a plan view in the vehicle front-rear direction of said lower portion is thickened.

According to the above configuration, the engine sound (powertrain sound) on the upper surface of the subframe is prevented from reverberating and resonating with the tunnel, improving the soundproofing performance, and mud and snow melting agent between the sound absorbing material and the upper surface. It is possible to simultaneously prevent the occurrence of rust caused by remaining .

According to the above Symbol configuration, the peripheral portion of the comparison to said lower portion and lower portion than the steering gear unit by thickened, can increase the irregularities with a steering gear unit above the sub-frame, which Therefore, excellent diffusibility can be obtained so that the engine sound does not propagate backward.

  Furthermore, according to the above configuration, it is possible to reduce the size of the soundproofing material by thinning the portion overlapping with the steering gear unit having high rigidity (high natural frequency).

In an embodiment of the present invention, a power train including the engine has been covered at least above the rear in thermal and acoustical insulation material, and said sub-extending Oite vehicle width direction towards after the powertrain A space through which the exhaust pipe passes rearward is provided above the frame .

  According to the said structure, while being able to improve the warm air and air resistance by the heat management of a power train, the sealing property of the power train as a sound source can be improved with a sound absorbing material.

  As the heat insulating soundproofing material, for example, at least one of a sound absorbing material formed in a nonwoven fabric shape or a porous shape and a sound insulating material formed of resin, aluminum, or the like can be used.

  According to this invention, propagation of engine sound from the engine room to the passenger compartment can be suppressed.

The longitudinal cross-sectional view which shows the principal part of the vehicle front part provided with the front sub-frame of this embodiment. The top view of the front sub-frame of this embodiment provided with the sound insulation member. FIG. 3 is a perspective cross-sectional view of the vicinity of a suspension cross viewed from the upper front side with respect to the line AA in FIG. 2. FIG. 3 is an essential part cross-sectional view taken along line AA in FIG. 2. Sectional drawing of the principal part of the BB line in FIG. Sectional drawing of the principal part of the CC line | wire in FIG. The perspective view which looked at the sound insulation member from the upper part. The perspective view which looked at the sound insulation member from the lower part. The front view and left view of a sound insulation member. The top view and bottom view of a sound insulation member.

An embodiment of the present invention will be described below with reference to the drawings.
First, the first embodiment will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view of a front portion of a vehicle in which the front subframe of the present embodiment is adopted, and is a vertical cross-sectional view partially showing a main portion of a vehicle width direction central portion of the front portion of the vehicle Is a plan view of the front sub-frame of the present embodiment provided with a sound insulation member, FIG. 3 is a perspective cross-sectional view of the periphery of the suspension cross viewed from the upper front side with respect to the line AA in FIG. 2, and FIG. FIG. 5 is a sectional view showing the end surface of the BB line in FIG. 2, FIG. 6 is a sectional view showing the end surface of the CC line in FIG. 2, and FIG. FIG. 8 is a perspective view of the sound insulation member as viewed from below, FIG. 9 (a) is a front view of the sound insulation member, FIG. 9 (b) is a left side view of the sound insulation member, and FIG. (A) is a top view of a sound insulation member, FIG.10 (b) is a bottom view of a sound insulation member. In FIG. 1, the engine is schematically shown for convenience. In the following description, in the drawings, arrow F indicates the front of the vehicle, arrow R indicates the right side of the vehicle, arrow L indicates the left side of the vehicle, and arrow U indicates the upper side of the vehicle.

  The vehicle V of the present embodiment employs a so-called front engine front drive system (FF system) in which the engine 1 which is an internal combustion engine is mounted on the front portion of the vehicle V and drives the front wheels F, as shown in FIG. In the front part of the vehicle V according to the present embodiment, an engine room E for accommodating a power train PT including the engine 1 and a transmission (not shown) is provided. In the engine room E, the front side of the vehicle V is partitioned by a front grill 2, a front bumper 3, and a shroud panel 4, and the rear side of the vehicle V is partitioned by a dash panel 5 and a cowl panel 6 that extend in the vertical direction.

  Further, the engine room E is partitioned from the outside by a hood 7 that extends horizontally in the upper part of the vehicle and an under cover 8 that also extends in the horizontal direction in the lower part of the vehicle. Further, the side of the engine room E is partitioned by a wheel house and a wheel apron that cover the front wheel F although not shown.

  The under cover 8 is formed in a flat plate shape, and as shown in FIG. 1, the front end portion is fixed to the lower end portion of the front bumper 3 with screws B1 and the like, and the middle portion in the front-rear direction is attached to the front cross member 22 described later. The rear portion is fixed to the center cross member 23 and the rear end is fixed to the suspension cross 24 with screws B1 or the like, so that the rear portion is disposed below the engine room E.

  By mounting the under cover 8 below the engine room E, it is possible to prevent the traveling wind flowing below the vehicle V from flowing into the engine room E when the vehicle is traveling and to improve the aerodynamic characteristics below the vehicle V. Thus, it functions as a sound insulating material that prevents engine sound from leaking from below the vehicle V.

  The dash panel 5 is formed in the vehicle width direction so as to partition the engine room E and the vehicle compartment C in the front-rear direction. That is, a front space separated from the vehicle compartment C by the dash panel 5 is set in the engine room E.

  A floor panel 9 is bonded and fixed to the lower rear end of the dash panel 5. The floor panel 9 extends substantially horizontally toward the rear and constitutes the bottom surface of the passenger compartment C. The floor panel 9 protrudes toward the passenger compartment C at the center in the vehicle width direction of the floor panel 9 and extends in the front-rear direction. A floor tunnel 11 (hereinafter referred to as “tunnel portion 11”) extending to the floor panel 9 is integrally formed with the floor panel 9.

  As shown in FIG. 1, the exhaust system of the engine 1 employs a so-called rear exhaust layout in which an exhaust manifold 12 and a catalyst 14 for reducing NOx are disposed on the rear side of the vehicle V.

  Specifically, an exhaust manifold 12 is connected to a cylinder head of the engine 1 mounted in the engine room E via an exhaust port (not shown), and exhaust gas from the engine 1 is connected to the exhaust manifold 12. An exhaust pipe 13 leading to an exhaust silencer (not shown) at the rear of the vehicle V is connected. The exhaust pipe 13 is disposed in the tunnel portion 11 and extends toward the rear of the vehicle V. The catalyst 14 is provided on the downstream side of the connection portion with the exhaust manifold 12 in the exhaust pipe 13.

  A top cover 15 as an engine cover is disposed above the engine room E and below the bonnet 7. The top cover 15 is a heat insulating soundproof material extending in the front-rear direction from the upper end of the shroud panel 4 to the front end of the cowl panel 6 so as to cover substantially the entire engine 1 from above. The top cover 15 is not limited to the configuration provided as the engine cover on the engine room E side of the vehicle V, and may be configured to be attached to the back surface of the bonnet 7.

  Further, a rear cover 16 is disposed behind the engine room E and on the front side of the dash panel 5 so as to extend downward from the rear portion of the top cover 15. The rear cover 16 is a heat insulating soundproof material that extends rearward so as to close a gap in the front-rear direction between the top cover 15 and the cowl panel 6 and extends downward so as to hang down from the rear end. Both the top cover 15 and the rear cover 16 are formed of a heat-resistant member such as ABS resin so as to have a sound insulation function (sound insulation function) in addition to a heat insulation function.

The center portion of the rear cover 16 in the vehicle width direction extends downward to a position before the rear lower end of the rear cover 16 interferes with the exhaust pipe 13, that is, to a position spaced apart from the exhaust pipe 13.
As described above, the engine room E includes the top cover 15 disposed above, the under cover 8 disposed below, the shroud panel 4 disposed on the front, the rear cover 16 disposed on the rear, and left and right (not shown) disposed on the sides. A wheel house, a wheel apron, and the like cover substantially the entire circumference, and these covers (panels) contribute to preventing the noise of the engine 1 from propagating to the outside, particularly to the passenger compartment C.

  However, as shown in FIG. 1, the space 17 (the engine room E and the tunnel portion 11 communicate with each other below the center of the rear cover 16 in the vehicle width direction, that is, behind the engine room E and in the center of the vehicle width direction. The exhaust pipe 13 extends from the engine room E to the tunnel portion 11 through the space 17. That is, since the engine sound propagates from the engine room E to the tunnel portion 11 through the space 17, an intrusion path of the engine sound from the floor panel 9 into the vehicle compartment C remains behind the engine room E.

  As shown in FIG. 1, a front subframe 20 (hereinafter referred to as “subframe 20”) to which a lower arm of a front wheel suspension device is attached is located behind and above the undercover 8 in the engine room E, that is, below the space 17. Is provided).

  As shown in FIG. 2, the subframe 20 includes a suspension cross member 24 (hereinafter referred to as “suspension cross 24”) as a main body of the subframe 20 that connects a pair of left and right front and rear members 21 and 21 and a rear end of the front and rear member 21 in the vehicle width direction. And a front cross member 22 that connects the front portions of the front and rear members 21 in the vehicle width direction, and is configured as a so-called perimeter formed in a substantially quadrilateral frame shape in plan view. The subframe 20 is attached to a front side frame (not shown) located above via a connecting portion (not shown).

  The front and rear members 21 and the suspension cloth 24 are each formed in a hollow shape by joining an upper panel 20u that constitutes an upper surface and a lower panel 20d that constitutes a lower surface. Among these members, the front / rear member 21 is formed of a cylindrical body having a closed cross section extending in the front / rear direction of the vehicle V.

  Reference numeral 25 in FIG. 2 is an extension frame (sub-crash can) extending from the front end of the front and rear members 21 to the front of the vehicle V via a plate-like flange, and reference numeral 26 is a connection of the front end of the extension frame in the vehicle width direction. Reference numeral 23 denotes a center cross member extending in the vehicle width direction behind the front cross member 22 and in front of the suspension cross 24. In FIG. 1, the sub-bumper beam 26 is not shown.

As shown in FIGS. 1 to 3, a steering gear unit 30 serving as an auxiliary device that transmits an operation amount of a steering wheel (not shown) to the left and right front wheels F is provided above the subframe 20. Is a steering rack 31 (see FIGS. 1 and 3) extending in the vehicle width direction at a position spaced upward with respect to the suspension cross 24 in the subframe 20, and a pinion 32 (gear box) linked to the steering rack 31 ( 2 and FIG. 3). As shown in FIGS . 2 and 3 , the steering rack 31 is fastened and fixed to the suspension cross upper surface 24a by using bolts B5 and the like via attachment members 33 that extend downward on the left and right sides in the vehicle width direction. . The pinion 32 is linked to a steering wheel (not shown) via a steering shaft (not shown).

  Above the sub-frame 20, there are provided only one wheel bump by resistance of torsional rigidity, and a stabilizer 35 (also referred to as a torsion beam) known as an auxiliary machine that suppresses the roll angle when rebounding. An intermediate portion 35 a corresponding to the suspension cross 24 in the vehicle width direction of the stabilizer 35 extends horizontally in the vehicle width direction in parallel with the steering rack 31 at the same height as that of the steering rack 31. As shown in FIG. 2, the left and right ends of the vehicle width direction intermediate portion 35a of the stabilizer 35 are fastened and fixed to the upper surface 24a of the suspension cross 24 by means of bolts B6 or the like via a mounting bracket 37.

  As shown in FIGS. 1 to 5, the sub-frame 20 is provided with a sound absorbing material 40 along the upper surface 24 a of the suspension cloth 24 extending in the vehicle width direction.

  As shown in FIGS. 7 to 9A, 10B, 10A, and 10B, the sound absorbing material 40 includes a sound absorbing material main body 41 and mounting legs 42 attached to the upper surface 24a of the suspension cloth 24. And is formed. In this example, the sound absorbing material 40 includes four mounting legs 42 (42a, 42b, 42c, 42d). Specifically, the sound absorbing material 40 includes a front left mounting leg portion 42a formed on the front side and the left end, a front right mounting leg portion 42b formed on the front side and the right end, and a rear side formed on the left end. It includes a left mounting leg portion 42c and a rear right mounting leg portion 42d formed on the rear side and the right side.

  Of these four mounting legs 42, the rear left mounting leg 42c includes an extended portion 43 extending downward from the sound absorbing material main body 41 and a flat flange portion having an insertion hole 44a formed through the central portion. 44 is formed in a substantially L shape in a longitudinal sectional view.

  Of the four attachment legs 42, the front left attachment leg 42a, the front right attachment leg 42b, and the rear right attachment leg 42d are all stepped first extensions extending downward from the sound absorbing material main body 41. A protruding portion 43a (see FIG. 10A), a flat extending portion 43b extending in a flat shape substantially parallel to the sound absorbing material main body 41, and a second extending downward from the flat extending portion 43b. The extending portion 43c is formed by a flat flange portion 44 having an insertion hole 44a (see FIG. 7) formed through the center portion.

That is, in each of these three attachment legs 42a, 42b, 42d, the flat extension 43b is located in the middle between the sound absorbing material main body 41 and the flange 44 in the vertical direction, and the sound absorbing material main body 41 has a flange. The first extending portion 43a and the second extending portion 43c extend downward in two stages through the flat extending portion 43b until reaching the portion 44.
In other words, each of these three mounting legs 42a, 42b, 42d is arranged in the order of the sound absorbing material main body 41, the flat extension 43b, and the flange 44 in FIG. 8 when the sound absorbing material 40 is viewed from the bottom side. It is arrange | positioned so that it may be located below (from the back side of the paper surface of FIG. 8). That is, the first extending portion 43a is formed in a vertical wall shape (step shape) rising from the sound absorbing material main body portion 41 toward the flat extending portion 43b toward the front side of the sheet of FIG. The extending portion 43c is formed in a vertical wall shape (step shape) rising from the flat extending portion 43b toward the flange portion 44 in the bottom view as viewed from the front side of FIG.

  Of these four mounting legs 42 (42a, 42b, 42c, 42d), the front left mounting leg 42a is positioned at the front and left side of the upper surface 24a of the suspension cloth 24 (see FIGS. 2 and 6). The right mounting leg portion 42b is at the front and right side position of the upper surface 24a of the suspension cloth 24 (see FIG. 3), and the rear left mounting leg portion 42c is at the rear and left side position of the upper surface 24a of the suspension cloth 24 (see FIG. The rear right mounting leg portion 42d is attached to the rear and right side positions of the upper surface 24a of the suspension cloth 24 (see FIGS. 2 and 6) using fasteners B2 and the like that are inserted through the insertion holes 44a, respectively. ing.

  As described above, the sound-absorbing material 40 has at least the sound-absorbing material main body 41 as the suspension cloth 24 in a state where the four attachment legs 42 are attached to the upper surface 24a of the suspension cloth 24, as shown in FIGS. On the other hand, it can be arranged in a state of being separated upward, that is, in a floating state, and a vertical gap S can be ensured between the lower surface of the sound-absorbing material main body 41 and the upper surface 24a of the suspension cloth 24.

  Specifically, the sound absorbing material 40 is in a state in which only the flange portions 44 of the four attachment leg portions 42 are installed on the upper surface 24a of the suspension cloth 24, and all of the sound absorbing material 40 other than the flange portion 44 including the sound absorbing material main body portion 41 are included. The parts are arranged in a state of being separated upward from the upper surface 24 a of the suspension cloth 24.

  As shown in FIGS. 1, 2 to 9A, 9B, the above-described sound absorbing material 40 is integrally formed in a state in which two panels of a sound absorbing panel 45 and a base panel 46 are overlapped. Has been. The sound absorbing panel 45 and the base panel 46 are formed in substantially the same shape in plan view.

  The sound absorbing panel 45 is formed by integral molding with a porous member, in this example, a urethane member, and the base panel 46 is formed with higher rigidity than the sound absorbing panel 45 by a metal plate such as stainless steel or aluminum. ing. As long as the base panel 46 is a member that can support the sound absorbing panel 45 from the lower side, the base panel 46 is not limited to a metal such as stainless steel or aluminum as in this example. Etc. can be formed.

As shown in FIG. 2, the sound absorbing material 40 is arranged in a state of overlapping (overlapping) the steering gear unit 30 and the stabilizer 35 in plan view.
In other words, the steering rack 31 and the stabilizer 35 are both disposed so as to straddle the sound absorbing material 40 in the vehicle width direction. On the other hand, the sound absorbing material 40 is disposed so as to straddle the steering rack 31, the stabilizer 35, and the vehicle V longitudinal direction.

  Of the mounting legs 42 described above, the front right mounting leg 42b, the rear left mounting leg 42c, and the rear right mounting leg 42d are the steering gear unit 30 and the steering gear 30 as auxiliary devices provided above the suspension cross 24. It is formed so as to avoid the rack 31.

  Specifically, among the mounting legs 42, the flange portion 44 of the front right mounting leg 42b is formed so as to enter under the pinion 32 provided in the steering gear unit 30 as an auxiliary machine. As a result, the front right mounting leg portion 42b is located immediately below the pinion 32 and provided at a position overlapping the pinion 32 in plan view (see FIG. 2), but is arranged so as not to interfere with the pinion 32 in the vertical direction. Has been.

  Further, as shown in FIGS. 2, 5, and 6, among the mounting legs 42, the flanges 44 of the rear left mounting leg 42c and the rear right mounting leg 42d are below the stabilizer 35 as an auxiliary machine. It is formed so that it may enter especially. Thus, the rear left mounting leg 42c is provided at a position overlapping the vehicle width direction intermediate part 35a of the stabilizer 35 in plan view (see FIG. 2), and the rear right mounting leg 42d is Although it is provided at a position close to the vehicle width direction intermediate portion 35a in plan view (see the figure), both are arranged so as not to interfere with the stabilizer 35 in the vertical direction.

Further, as shown in FIGS. 7, 8, 9 (a), 10 (a) and 10 (b), the sound absorbing material 40 includes a steering gear unit 30 as an auxiliary machine provided above the suspension cross 24. Escape portions (51, 52, 53, 54) are formed so as to avoid the above.
Specifically, as shown in FIG. 3 and FIG. 4, the sound absorbing material 40 has a downward concave shape that is formed as a relief portion in a concave shape in a portion corresponding to the steering rack 31 in a plan view in the sound absorbing material main body 41. 2 and 5, the left side formed corresponding to the left side mounting member 33 among the left side and right side mounting members 33, 33 to the suspension cross upper surface 24a of the steering rack 31, as shown in FIGS. As shown in FIGS. 6 and 7, the opening 52, the right groove 53 formed corresponding to the pinion 32 provided in the steering gear unit 30, and the rear groove formed corresponding to the propeller shaft (not shown). 54.

  As shown in FIGS. 3, 7, and 8, the lower concave portion 51 connects the first extending portion 43 a and the left opening 52 in the vehicle width direction so as to surround the substantially lower half of the steering rack 31. The sound absorbing material 40 is formed in an intermediate portion in the front-rear direction of the sound absorbing material main body 41 in a substantially semicircular concave shape in the cross-sectional view along the vehicle width direction.

  As shown in FIG. 7, the left opening 52 is formed by penetrating the boundary portion of the sound absorbing material main body 41, the front left mounting leg 42 a and the rear left mounting leg 42 c and its peripheral portion in the thickness direction. is there. The right groove 53 is formed such that the boundary between the front right mounting leg 42b and the rear right mounting leg 42d and its peripheral part are cut out in the vehicle width direction from the right end (see the same figure). The rear groove portion 54 is formed by notching the intermediate portion in the vehicle width direction of the sound-absorbing material main body portion 41 from the rear end to the front (see the same figure).

As shown in FIG. 7, the sound absorbing material 40 is formed with raised portions 55 (55 a, 55 b, 55 c) that protrude above the upper surface of the sound absorbing material main body 41.
The raised portion 55 is formed by thickening a part of the sound absorbing panel 45, and the inside thereof is made solid by urethane forming the sound absorbing panel 45. The raised portion 55 is formed so as to be at least partially adjacent to the lower concave portion 51. Specifically, as shown in FIG. 3 and FIG. 7, the front side of the lower concave portion 51 in the sound absorbing material main body 41 is provided. And a front raised portion 55a extending along the front edge of the lower concave portion 51 at a position on the right side of the vehicle V, and a rear groove portion on the rear side of the lower concave portion 51 of the sound-absorbing material main body portion 41 as shown in FIG. As shown in FIG. 7, it is formed at a position on the rear side of the lower concave portion 51 of the sound absorbing material main body 41 and on the left side of the rear groove portion 54, as shown in FIG. And a left rear raised portion 55c.

  The above-described front subframe 20 of the present embodiment has a front subframe structure that extends in the vehicle width direction behind the engine 1 and supports a lower arm 27 provided in a suspension (not shown) of the front wheel F (see FIGS. 1 and 2). 2) A sound absorbing material 40 is provided along the suspension cross upper surface 24a below the exhaust pipe 13 extending from the engine 1 to the rear tunnel portion 11 (see FIGS. 1 and 2). 41 and a mounting leg portion 42 as a subframe mounting portion to be attached to the subframe 20 (see in particular FIG. 7), and the sound absorbing material 40 has a mounting leg portion 42 projecting downward with respect to the sound absorbing material main body portion 41. As a result, it is disposed away from the suspension cross upper surface 24a (see FIGS. 1 and 3 to 6).

  According to the above configuration, the engine sound (powertrain PT sound) on the suspension cross upper surface 24a is prevented from reverberating and resonating to the tunnel portion 11 to improve the soundproof performance, and between the sound absorbing material 40 and the suspension cross upper surface 24a. It is possible to achieve both prevention of rust due to mud and snow melting agent residue.

  Specifically, the suspension cloth 24 provided in the sub-frame 20 extending in the vehicle width direction has a substantially flat wide upper surface 24a. Conventionally, the engine sound is reflected on the upper surface 24a of the suspension cloth so that the tunnel portion 11 It was easy to propagate backwards. Since the sub-frame 20 is positioned above the under cover 8 (see FIG. 1), the engine sound reflection on the upper surface 24a of the suspension cloth is an insulator (soundproof material) (not shown) on the upper surface of the under cover 8 as in the prior art. Even if it was provided, it could not be prevented.

  On the other hand, in the sub-frame 20 of the present embodiment, the sound absorbing material 40 is provided on the upper surface 24a of the suspension cloth 24, so that the engine sound (power train PT sound) on the suspension cloth upper surface 24a is prevented from reverberating and resonating. Soundproof performance can be improved.

  However, even if a sound absorbing material is simply provided on the upper surface 24a of the suspension cloth 24, if the suspension upper surface 24a is exposed to water, the sound absorption panel having excellent water absorption due to the porous structure absorbs water, so that the water absorption state is maintained for a long time. Is not preferable from the viewpoint of securing the rust prevention property of the suspension cloth 24. Particularly in cold regions, snow melting agents (freezing agents) such as sodium chloride and calcium chloride are often sprayed on the road, so that mud and snow melting agents remain between the sound absorbing material 40 and the upper surface 24a of the suspension cloth 24. There was a risk that the risk of rusting due to aging would become significant.

  Therefore, in the present embodiment, the sound absorbing material main body 41 of the sound absorbing material 40 is floated from the upper surface 24a of the suspension cloth 24 and then attached to the upper surface 24a of the suspension cloth 42 by the attachment legs 42, so that water, salt, mud, etc. are present on the suspension cloth upper surface 24a. Accumulation can be prevented, and the rust prevention property of the suspension cloth 24 can be enhanced. It is possible to achieve both prevention of rust generation due to mud and snow melting agent remaining between the sound absorbing material 40 and the suspension cloth upper surface 24a.

  Furthermore, the sound absorbing material 40 includes a base panel 46 that is more rigid than the sound absorbing panel 45, so that water remaining on the upper surface 24 a of the suspension cloth 24 does not adhere to the sound absorbing material 40 through the gap S between the suspension cloth upper surface 24 a and the sound absorbing material 40. It can be kept at a predetermined height.

  Moreover, in the present embodiment, the mounting leg portion 42 that supports the sound absorbing material main body 41 in a state where it floats from the upper surface 24a of the suspension cloth 24 is arranged such that the front right mounting leg portion 42b enters under the pinion 32, for example. (See FIGS. 3 and 6), the rear left mounting leg portion 42c and the rear right mounting leg portion 42d are disposed so as to enter under the vehicle width direction intermediate portion 35a of the stabilizer 35 (see FIGS. 2, 5, and 6). ) Etc., for example, the mounting leg 42 and the auxiliary devices such as the pinion 32 and the stabilizer 35 are arranged so as to overlap with each other in a plan view, thereby ensuring compactness and not interfering with the auxiliary devices (32, 35). It is provided as follows.

  Furthermore, the sound absorbing material 40 of the present embodiment has a sound absorbing property by having a sound absorbing panel 45 on the entire upper surface of the base panel 46 including the mounting leg portion 42 as well as the sound absorbing material main body 41. To further prevent reflection of the engine sound to the rear, and depending on the location, a raised portion 55 (55a, 55b, 55c) is provided to increase the sound absorption of the engine sound. At the same time, diffusibility can be enhanced.

  As described above, the sound absorbing material 40 according to the present embodiment forms the left opening 52 as the opening and the right groove 53 and the rear groove 54 as the groove in a portion corresponding to the auxiliary equipment such as the steering gear unit 30 and the stabilizer 35. Since the mounting recess 42 is provided so as to form the lower concave portion 51 as the escape portion recessed downward, and to enter the auxiliary machinery (30, 35) as described above, the auxiliary machinery (30 , 35) and covering the upper surface 24a of the suspension cross 24 in a separated state while avoiding interference with the sound, the rearward transmission due to the reflection of the engine sound can be prevented (see FIGS. 3 to 6).

  Since the sound absorbing material 40 is provided on the upper surface 24a of the suspension cloth 24 as in the present embodiment, it is possible to prevent the engine sound from propagating to the tunnel portion 11, and therefore, for example, the engine sound propagated to the tunnel portion 11 Since the floor panel 20d9 does not need to be provided with a soundproof panel such as an insulator, unlike the conventional structure, the vehicle V can be reduced in weight and the vehicle can be reduced. The space of the chamber C can be secured.

  As an aspect of the present invention, the steering gear unit 30 is spaced above the upper surface 24a of the suspension cross 24 and extends in the vehicle width direction, and the sound absorbing material 40 is disposed below the steering gear unit 30, A raised portion 55 (55a, 55b, 55c) is provided as a configuration in which the peripheral portion of the lower concave portion 51 is thicker than the lower concave portion 51 as a lower portion than the steering gear unit 30 ( 1 to 6).

  According to the above configuration, excellent diffusibility can be obtained so that the engine sound does not propagate backward by increasing the uneven shape in cooperation with the steering gear unit 30 above the subframe 20.

  More specifically, for example, the steering rack 31 and the pinion 32 provided in the steering gear unit 30 have high rigidity and high natural frequency, so that they are difficult to resonate with engine sound. Furthermore, since the steering rack 31 has a substantially cylindrical shape extending in the vehicle width direction, it can be said that the outer peripheral surface of the steering rack 31 is less likely to reflect the engine sound to the rear than the flat surface, and the propagating ability of the engine sound to the rear is relatively low.

  In the present embodiment, the upper portion of the steering rack 31 is not covered with the sound absorbing material 40, and the sound absorbing material 40 is provided with a lower concave portion 51 as a relief portion below the steering gear unit 30 and a lower concave portion. A raised portion 55 thicker than the lower concave portion 51 is arranged in a peripheral portion of the lower portion 51.

  As a result, by providing the sound absorbing material 40 in a concavo-convex shape around the periphery of the steering gear unit 30 other than the upper part, the concavo-convex shape can be increased together with the steering rack 31 above the suspension cross 24 in the vehicle width direction. However, it is possible to obtain excellent sound diffusivity utilizing the diffusibility of the engine sound of the substantially circular steering rack 31.

  Further, according to the above configuration, the sound absorbing material 40 is formed by thinning the portion overlapping the highly rigid (high natural frequency) steering gear unit 30, that is, by forming the lower concave portion 51 in the portion corresponding to the steering rack 31. Since it can be made compact, it is possible to achieve both layout properties with auxiliary equipment such as the steering gear unit 30 above the suspension cross 24 while maintaining the sound absorption effect of the engine sound.

  Further, as an aspect of the present invention, the power train PT including the engine 1 is covered with a top cover 15 and a rear cover 16 as heat insulating soundproofing materials (sound absorbing materials or sound insulating materials) at least from above and behind, and A space 17 through which the exhaust pipe 13 passes rearward is provided above the suspension cloth 24 extending in the vehicle width direction behind the power train PT (see FIG. 1).

  According to the above configuration, it is possible to improve the warm air and air resistance by the thermal management of the power train PT, and improve the sealing performance of the power train PT as a sound source in combination with the sound absorbing material 40.

  The present invention is not limited only to the configuration of the above-described embodiment, and many embodiments can be obtained.

  For example, in the embodiment described above, the sound absorbing panel 45 is formed by integrally forming the sound absorbing material main body 41 and the mounting leg portion 42. However, the present invention is not limited to this embodiment. And a mounting leg member as a bracket formed of a separate member, and the mounting leg member is interposed between the upper surface 24a of the suspension cloth 24 and the sound absorbing material main body 41, so that the sound absorbing material main body 41 is attached by the mounting leg member. You may employ | adopt the structure supported in the state which floated with respect to the upper surface 24a of the suspension cloth 24. FIG.

  As the heat insulating and soundproofing material such as the top cover 15 and the rear cover 16, for example, at least one of a sound absorbing material formed in a porous shape and a sound insulating material formed of resin, aluminum, or the like can be used.

  Further, as in the present embodiment, the structure in which the sound absorbing material 40 is disposed on the upper surface 24a of the suspension cloth 24 may be applied to an electric vehicle or a fuel cell vehicle. When applied to an electric vehicle, it is possible to prevent the motor sound from propagating to the vehicle compartment C side. When applied to a fuel cell vehicle, the sound of a blower fan for sending air into the fuel cell is detected. Propagation to the side can be prevented.

DESCRIPTION OF SYMBOLS 1 ... Engine 11 ... Tunnel part 13 ... Exhaust pipe 15 ... Top cover (heat insulation soundproofing material)
16 ... Rear cover (heat insulation and soundproofing material)
20 ... Front subframe (front subframe structure )
2 4a: Suspension top surface (subframe top surface)
27: Lower arm 30 of the suspension ... Steering gear unit 40 ... Sound absorbing material 41 ... Sound absorbing material body 42 ... Mounting leg (subframe mounting)
51. Lower concave part (lower part than steering gear unit)
55 ... Bump (thickened peripheral part of the lower part)
55a ... Front side bulge (thickened peripheral part of the lower part)
55b ... Right rear bulge (thickened peripheral part of the lower part)
55c ... Left rear raised part (thickened peripheral part of the lower part)
PT ... Powertrain

Claims (3)

A front subframe structure that extends in the vehicle width direction behind the engine and supports the suspension of the front wheels,
Under the exhaust pipe extending from the engine to the rear tunnel, a sound absorbing material is provided along the upper surface of the subframe.
The sound absorbing material includes a sound absorbing material main body portion and a subframe attachment portion attached to the subframe,
The sound absorbing material is a front subframe structure in which the subframe mounting portion protrudes downward from the sound absorbing material main body portion so as to be separated from the upper surface of the subframe. A steering gear unit is spaced above the upper surface of the subframe and extends in the vehicle width direction;
2. The front subframe structure according to claim 1, wherein the sound absorbing material is disposed below the steering gear unit, and a peripheral portion of the lower portion is thicker than the lower portion of the steering gear unit. . The power train including the engine is covered with a heat insulating soundproof material from at least above and from behind, and the exhaust pipe is located behind the cross member extending in the vehicle width direction at the rear of the power train. The front sub-frame structure according to claim 1 or 2, wherein a space for passing through is provided.

Images