JP2018161981A - Front sub-frame structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a front sub-frame structure that hinders vibration (low frequency vibration) of a cross member body, is able to improve feeling of rigidity as well as arm support rigidity in a vehicle width direction, and is able to enhance steering stability.SOLUTION: A front sub-frame A comprises a cross member body 20 having a front support part 27 for right and left suspension arms 10. In respective parts of the right and left suspension arms 10, which are offset further forward and downward than the support center of the front support part 27, coupling parts 28 for a reinforcement member are provided. A reinforcement member 29 for coupling the right and left coupling parts 28 straight in a vehicle width direction is provided.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a front subframe structure in a horizontally mounted engine and a front wheel drive type automobile.

Generally, the front sub-frame includes a cross member main body that supports a lower arm as a left and right suspension arm and attaches a power train to an upper portion thereof.
Since the powertrain is heavy, it is required to be placed in the center of the vehicle longitudinal direction as much as possible in consideration of the reduction of the moment of inertia of the vehicle, while the position to support the front wheels is specified, and the lower arm Ideally, the lower arm support portion is provided on the cross member main body at a position substantially next to the knuckle support portion in the vehicle width direction.

  For this reason, the position where the power train is disposed and the lower arm support portion are usually offset in the vehicle front-rear direction, and vibrations transmitted from the wheels in the lateral direction (low frequency vibrations of about 300 Hz) are road noise. In order to suppress transmission to the chamber, a structure is employed in which a reinforcing member that connects the left and right lower arm support portions in the vehicle width direction is attached to the cross member body.

  Patent Document 1 discloses a configuration in which a reinforcing member for connecting left and right lower arm support portions in the vehicle width direction is provided on a cross member body.

  However, in the conventional structure disclosed in Patent Document 1, a reinforcing effect is obtained because the vehicle width direction intermediate portion of the reinforcing member is bent in the front-rear direction so as to be located slightly in front of the vehicle with respect to both ends thereof. There was also room for improvement in terms of improving the arm support rigidity in the vehicle width direction.

JP 2006-112976 A

  Therefore, the present invention suppresses vibration (low frequency vibration) of the cross member main body, improves the rigidity feeling, improves the arm support rigidity in the vehicle width direction, and improves the maneuverability. The purpose is to provide a structure.

  A front subframe structure according to the present invention is a front subframe structure in a horizontally mounted engine and front wheel drive type automobile, and the front subframe includes a cross member main body having front support portions of left and right suspension arms. In addition, a connecting portion for a reinforcing member is provided in a portion offset forward and downward from the support center of the front support portion of the left and right suspension arms, and the left and right connection portions are connected in a straight line in the vehicle width direction. The reinforcing member to be provided is provided.

  According to the above configuration, the left and right connecting portions are linearly connected in the vehicle width direction with the reinforcing member described above, so low frequency vibration of about 300 Hz of the cross member main body is suppressed and road noise is transmitted to the vehicle interior. In addition to being able to suppress this, it is possible to improve the rigidity feeling, improve the arm support rigidity in the vehicle width direction, and improve the operability.

  In one embodiment of the present invention, the front subframe includes a cross member main body provided with a front support portion of the suspension arm and a connecting portion for the reinforcing member, and a vehicle from the left and right front ends of the cross member main body. And a side member extending forward.

  According to the said structure, the support rigidity of a side member can also be improved with the above-mentioned reinforcement member.

  In one embodiment of the present invention, the rear end portion of the reinforcing member is widened rearward to form a connecting portion of the suspension arm to the support bracket, and the front edge of the reinforcing member is formed in a straight line extending in the vehicle width direction. It has been done.

  According to the said structure, the further improvement of a feeling of rigidity and the further suppression of a low frequency vibration can be aimed at.

  According to the present invention, the vibration (low frequency vibration) of the cross member main body is suppressed, the rigidity feeling is improved, the arm support rigidity in the vehicle width direction can be improved, and the maneuverability can be improved. .

The perspective view which shows the front sub-frame structure of this invention Plan view of front subframe structure Bottom view of front subframe structure Side view of front subframe structure Front view of front subframe structure An enlarged plan view showing the cross member main body and its peripheral structure BB sectional view of FIG. An enlarged plan view showing a related structure of the side member, the crash can, the front cross member, and the extension part

  A horizontal engine and front-wheel drive aiming to improve the sense of rigidity by suppressing the vibration (low frequency vibration) of the cross member body and improving the arm support rigidity in the vehicle width direction. The front subframe has a cross member main body having front support portions for left and right suspension arms, and is located forward of the support center of the front support portions for the left and right suspension arms. In addition, the connecting portion for the reinforcing member is provided at the portion offset downward, and the reinforcing member for connecting the left and right connecting portions linearly in the vehicle width direction is provided.

An embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view of the front subframe structure, FIG. 2 is a plan view of FIG. 1, FIG. 3 is a bottom view of FIG. 1, and FIG. 4 is a left side view of FIG. 5 is a front view of FIG.

  1 to 5, in the front subframe structure of a horizontally mounted engine and front wheel drive type automobile, the front subframe A is provided at the lower part of the engine room at the front of the vehicle. The cross member main body 20 is composed of a plurality of members that support the left and right lower arms 10 as the left and right suspension arms (only the lower arm 10 on the left side of the vehicle is shown in the drawing), and the left and right front portions of the cross member main body 20. A pair of left and right side members 30, 30 extending in front of the vehicle (specifically, front side members, so-called extensions) and front end portions of the pair of left and right side members 30, 30 are connected to each other in the vehicle width direction. The front cross member 40 is provided.

  A sub-crash can 43 is attached to the front end portion of the side member 30 via a set plate 41 and a mounting plate 42, and extends in the vehicle width direction to the front end portions of the pair of left and right sub-crash cans 43, 43. A lower bumper reinforcement 44 is provided as a bumper reinforcement.

  A vehicle body attachment portion 45 (so-called pillar portion) extending in the vertical direction is provided at the front end portion of the side member 30 and immediately after the set plate 41. The vehicle body attachment portion 45 has an attachment member 46 extending upward. The vehicle body attachment portion 45 and the attachment member 46 described above are for attaching the side member 30 to a lower portion of a front side frame (not shown) that is a vehicle body. It is a member.

6 is an enlarged plan view showing the cross member main body and its peripheral structure, and FIG. 7 is a cross-sectional view taken along the line BB of FIG.
As shown in FIGS. 4 to 6, the lower arm 10 includes a knuckle support portion 11 located on the outer side in the vehicle width direction, and a front lower arm bush 12 serving as a vehicle body side mounting portion located on the inner front side in the vehicle width direction. And a lower arm bush 13 on the rear side as a vehicle body side mounting portion located on the inner rear side in the vehicle width direction.

  As shown in FIGS. 1 to 4 and 6, the cross member body 20 described above extends from the upper panel 21, the front lower panel 22, the rear lower panel 23, and the left and right sides of the upper panel 21 to the front of the vehicle. And an upper panel 24.

  Both the above-described extended upper panel 24 and the front lower panel 22 form an extended portion 25 extending forward from the upper panel 21 and the rear lower panel 23, and the above-described pair of left and right side members 30, 30. The rear end portion is connected and fixed to the front end portions of the pair of left and right extending portions 25, 25.

  As shown in FIGS. 1 to 4 and 6, both the upper panel 21 and the rear lower panel 23 project the rear side of the lower arm 10 so as to protrude outward in the vehicle width direction from the left and right rear portions of the cross member body 20. A rear support portion 26 that supports the lower arm bush 13 is formed.

  As shown in FIG. 6, an arm support bracket 27 that supports the lower arm bush 12 on the front side of the lower arm 10 is attached to the extended portion 25, and the lower arm bush 12 is supported by the arm support bracket 27. Yes.

  The arm support bracket 27 described above constitutes a front support portion of the suspension arm (lower arm 10). The support center of the front support portion, that is, the front and rear direction of the lower arm bush 12 supported by the arm support bracket 27 and the vehicle. A connecting portion 28 for a reinforcing member (for brace described later) is provided at a portion offset forward and downward from the center in the width direction.

  6 and 7, a line connecting the support centers of the left and right front support portions is indicated by a line L1. As shown in FIG. 6, the connecting portion 28 is positioned forward with respect to the line L1, and as shown in FIG. 7, the connecting portion 28 is positioned below with respect to the line L1.

  A brace 29 is provided as a reinforcing member that linearly connects the left and right connecting portions 28, 28 in the vehicle width direction. The brace 29 is linear when viewed from the front as shown in FIG. 5, and is also linear when viewed from the top as shown in FIG. Further, as the brace 29, a plate-like member having no bead is used. As shown in FIG. 7, in this embodiment, an attachment member such as a bolt 47 and a nut 48 is used. Both ends in the vehicle width direction are fastened and fixed to the connecting portion 28 described above, whereby a brace 29 is installed between the left and right connecting portions 28 and 28 in the vehicle width direction.

  Due to the above-described installation structure of the brace 29, a space S1 is formed between the front edge of the upper panel 21 and the front edge of the rear lower panel 23 and the rear edge of the brace 29, as shown in FIG.

  In this way, by connecting the left and right connecting portions 28, 28 in a straight line shape in the vehicle width direction with the brace 29, the front subframe A, especially the low frequency vibration of about 300 Hz of the cross member body 20 is suppressed, and the rigid In addition to improving the sensation, the lower arm support rigidity in the vehicle width direction is improved to improve the operability.

As shown in FIGS. 1, 2, 3, and 6, a plurality of under cover attachment portions 29 a and 29 a that extend stepwise from the front edge in the vehicle width direction intermediate portion of the brace 29 described above to the front of the vehicle are integrally formed. The torsional load from the under cover (not shown) is difficult to enter the brace 29, and the under cover mounting portion 29a can be attached to the under cover while the brace 29 increases the rigidity in the vehicle width direction. is there.
Specifically, the above-described under cover attaching portion 29a is formed on the brace 29 via two ridge lines X1 and X2, as shown in FIG.

Moreover, as shown in FIGS. 1-4, by providing the side member 30 extended from the left-right front end of the cross member main body 20, specifically, the vehicle front from the front end of the extension part 25, it is the above-mentioned. The brace 29 is configured to improve the support rigidity of the side member 30.
Here, the front sub-frame A described above has a perimeter frame structure composed of the elements 20, 25, 30, and 40.

As shown in FIGS. 3 and 6, the rear end portion of the brace 29 where the bolt 47 and the nut 48 are fastened is widened rearward to form a coupling portion 29 b for the arm support bracket 27. 29b, the front lower panel 22 and the arm support bracket 27 are fastened and fixed by a connecting member 49 such as a bolt or a nut, while the front edge 29c of the brace 29 is provided with an under cover attaching portion 29a. Except for this, it is formed in a straight line extending straight in the vehicle width direction.
As a result, the rigidity is improved and the low-frequency vibration is further suppressed.

  As shown in FIG. 6, the vehicle front-rear direction between the support center of the front support portion of the lower arm 10 (that is, the center in the front-rear direction and the vehicle width direction of the lower arm bush 12 supported by the arm support bracket 27) and the knuckle support portion 11. Are substantially the same, thereby improving the wheel support rigidity, and the position of the brace 29 in the vehicle longitudinal direction is located forward of the position of the knuckle support portion 11 in the vehicle longitudinal direction. By forming the space portion S1, the low-frequency vibration is reduced.

  3, 4, and 5, the front lower edge of the cross member main body 20, specifically, the front edge of the rear lower panel 23 is formed in a substantially horizontal shape. Even if it is not curved in the vertical direction as in a front-view sub-frame, the above brace 29 ensures the reinforcing effect and increases the rigidity.

  Further, as shown in FIGS. 1, 2, and 4 to 6, a plurality of stabilizer mounting brackets 50 are fastened and fixed to the upper panel 21 of the cross member main body 20, and FIGS. As shown in FIG. 5, a tower portion 51 (so-called “horn member”) extending upward from the extended upper panel 24 is provided at the base portion (that is, the rear portion) of the extended upper panel 24 of the cross member main body 20. The tower 51 is a member for attaching the cross member main body 20 to the lower portion of the front side frame (not shown).

  FIG. 8 is an enlarged plan view showing a related structure of a side member, a crash can (sub-crash can), a front cross member, and an extended portion.

As shown in FIG. 1 to FIG. 3 and FIG. 8, an extended portion 52 for preventing small overlap collision is provided that protrudes outward in the vehicle width direction from the front end portion of the side member 30.
As shown in the plan view of FIG. 8, the extended portion 52 is formed such that the side surface 52a on the outer side in the vehicle width direction is inclined inward in the vehicle width direction toward the rear of the vehicle body in a plan view of the vehicle. That is, the extended portion 52 is bonded and fixed to the front end portion of the side member 30 and the back surface of the set plate 41, and the amount of protrusion of the front end of the extended portion 52 outward in the vehicle width direction is outward of the rear end in the vehicle width direction. The side surface 52a is formed on the slant surface.

  As shown in FIG. 8, the center part in the front-rear direction of the front cross member 40 is disposed behind the vehicle body attachment part 45 and ahead of the rear end 52 b of the extension part 52. Further, both end portions of the front cross member 40 in the vehicle width direction are widened forward of the vehicle to form widened portions 40a and 40a.

  As shown in FIG. 8, when the center of rigidity when the above-described widened portions 40a and 40a are not present in the front cross member 40 is a line L2, if the widened portions 40a and 40a widened in front of the vehicle are formed, the rigidity is increased. The center is a line L3 and approaches the attachment member 46 (the rotation center of the extension portion 52 at the time of a small overlap collision) in the vehicle body attachment portion 45 in the vehicle longitudinal direction.

  As shown in the figure, an auxiliary machine 53 such as a heat exchanger is disposed in front of the front cross member 40, and the above-mentioned widened portions 40 a and 40 a are arranged in a vehicle more than the auxiliary machine 53 of the front cross member 40. It is formed by widening the width direction outer side part ahead of the vehicle. Further, as shown in FIG. 8, a power train 54 having a horizontally mounted engine is disposed behind the above-described front cross member 40.

  In this way, the front cross member 40 is disposed rearward of the vehicle body mounting portion 45, the center of rigidity of the front cross member 40 is projected from the line L2 to the line L3, and is brought close to the rotation center (see the mounting member 46). It is configured to reduce the obstruction of the side member 30 from being bent inward in the vehicle width direction by the extension portion 52, and to improve both the collision performance and the layout flexibility of the auxiliary machine 53. It is.

  That is, during a small overlap collision, when a collision load is input from the vehicle width direction end portion of the bumper reinforcement 44 to the extension portion 52 via the set plate 41, the collision load is rearward via the extension portion 52. When the load is transmitted to the side member 30, the load of the side member 30 is urged in the direction of rotation about the vehicle body mounting portion 45 (particularly, the vehicle body mounting member 46). 8, the side member 30 bends inward in the vehicle width direction, pushes the power train 54 with the side member 30, and the front part of the vehicle is A moment to move in the lateral direction is generated.

  In this case, if the front cross member is largely displaced rearward from the center of rotation (see the vehicle body mounting member 46), the front cross member inhibits the side member 30 from bending inward in the vehicle width direction. In the embodiment, since the center of rigidity of the front cross member 40 is projected forward from the line L2 to the line L3, it is possible to reduce the obstruction of the side member 30 from being bent inward in the vehicle width direction by the front cross member 40. It is something that can be done.

  As shown in FIG. 8, an auxiliary machine 53 such as a heat exchanger is disposed in front of the front cross member 40, and a vehicle width direction outer side portion of the front cross member 40 is widened forward of the vehicle. Since the widened portion 40a is formed, the layout is further improved. In particular, an auxiliary machine 53 such as a heat exchanger is arranged as far back as possible to make the arrangement compact, and at the time of a light collision. It is also possible to secure a load absorbing space at.

  Further, as shown in FIGS. 2 and 8, a lower bumper reinforcement 44 extending in the vehicle width direction is provided at the front end portion of the pair of left and right side members 30, 30 via the sub-crash cans 43, 43. A space S2 in the vehicle front-rear direction is provided between the front surface of the extension portion 52 and the rear surface of the lower bumper reinforcement 44 and outside the sub-crash can 43 in the vehicle width direction. Thereby, the collision load urged to the end portion in the vehicle width direction of the lower bumper reinforcement 44 is reliably transmitted to the sub-crash can 43 in a substantially straight line in the front-rear direction, and the sub-crash can 43 is crushed, After that, when a load is transmitted to the extension part 52, the side member 30 is promoted to bend and deformed so that both the absorption of the collision load by the sub-crash can 43 and the occurrence of the folding of the side member 30 are compatible. It is.

  In addition, as shown in FIG. 8, a concave bent portion extending inward in the vehicle width direction and extending in the up-down direction of the side member 30 is provided at a portion spaced rearward from the rear end 52 b in the extended portion 52 of the side member 30. The promotion part 31 is provided, and the above-described power train 54 is provided inside the bending promotion part 31 in the vehicle width direction. Thereby, when the side member 30 is bent and deformed, the side member 30 is bent and deformed inward in the vehicle width direction, causing interference with the power train 54 and generating a lateral movement moment that moves the front portion of the vehicle in the lateral direction. Thus, the vehicle front portion is configured to move laterally in a direction to escape from the collision object.

  As shown in FIG. 4, the front end portion and the extension portion 52 of the side member 30 described above are substantially horizontal, and the side member 30 is formed such that the rear portion bends downward from the rear end 52 b of the extension portion 52. Yes. By constructing the above-mentioned extension part 52 substantially horizontally, the twist of the rotational moment at the extension part 52 is suppressed.

  In short, the front sub-frame structure of the above embodiment avoids the auxiliary machine 53 and disposes the front cross member 40 behind the vehicle body mounting member 46 of the vehicle body mounting portion 45, while maintaining the rigidity center of the front cross member 40 ( The front cross member 40 does not hinder the bending of the side member 30.

Here, when the rear end 52b of the extended portion 52 extends rearward to the bend promoting portion 31 as indicated by a virtual line β in FIG. 8, the inner side in the vehicle width direction when the side member 30 is bent. In this embodiment, the rear end 52b of the expansion portion 52 is separated from the bending promoting portion 31 in the forward direction.
In the figure, arrow F indicates the front of the vehicle, arrow R indicates the rear of the vehicle, arrow IN indicates the inward in the vehicle width direction, arrow OUT indicates the outward in the vehicle width direction, and arrow UP indicates the upper side of the vehicle. Indicates.

  As described above, the front subframe structure of the above embodiment is a horizontal engine and a front subframe structure in a front-wheel drive type automobile, and the front subframe A includes left and right suspension arms (see the lower arm 10). A cross member body 20 having a front support portion (see arm support bracket 27) is provided, and is offset forward and downward from the support center of the front support portion (arm support bracket 27) of the left and right suspension arms (lower arm 10). The connecting portion 28 for the reinforcing member is provided in the part, and the reinforcing member (see the brace 29) for connecting the left and right connecting portions 28 linearly in the vehicle width direction is provided (FIG. 1, FIG. 1). (See FIG. 6).

  According to this configuration, the left and right connecting portions 28 and 28 are linearly connected in the vehicle width direction by the above-described reinforcing member (brace 29), so that low frequency vibration of about 300 Hz of the cross member main body 20 is suppressed. The road noise can be prevented from being transmitted to the passenger compartment, the rigidity can be improved, the arm support rigidity in the vehicle width direction can be improved, and the operability can be improved.

  In one embodiment of the present invention, the front subframe A is provided with a front support portion (arm support bracket 27) of the suspension arm (lower arm 10) and a connecting portion 28 for the reinforcing member. A cross member main body 20 and a side member 30 extending forward from the left and right front ends of the cross member main body 20 are provided (see FIGS. 1 and 6).

  According to this structure, the support rigidity of the side member 30 can also be improved by the above-mentioned reinforcing member (brace 29).

  Furthermore, in one embodiment of the present invention, the rear end portion of the reinforcing member (brace 29) is widened rearward to form a coupling portion 29b for the suspension arm (lower arm 10) to the support bracket (arm support bracket 27). The front edge 29c of the reinforcing member (brace 29) is formed in a straight line extending in the vehicle width direction (see FIGS. 3 and 6).

  According to this configuration, it is possible to further improve the rigidity and further suppress low-frequency vibration.

In the correspondence between the configuration of the present invention and the above-described embodiment,
The suspension arm of the present invention corresponds to the lower arm 10 of the embodiment,
Similarly,
The front support portion corresponds to the arm support bracket 27,
The reinforcement member corresponds to the brace 29,
The present invention is not limited to the configuration of the above-described embodiment.

  For example, in the above embodiment, as shown in FIG. 4, the cross member body 20 is divided into the upper panel 21, the extended upper panel 24, the front lower panel 22, and the rear lower panel 23. And an extended upper panel 24 and a lower panel in which the front and rear lower panels 22 and 23 are integrally formed.

  As described above, the present invention is useful for a front subframe structure in a horizontally mounted engine and a front-wheel drive type automobile.

A ... Front subframe 10 ... Lower arm (suspension arm)
20 ... Cross member main body 27 ... Arm support bracket (front support part)
28 ... Connecting part 29 ... Brace (reinforcing member)
29b ... coupling part 30 ... side member

Claims (3)

A front subframe structure in a horizontally mounted engine and a front wheel drive type automobile,
The front subframe includes a cross member body having front support portions of left and right suspension arms,
A connecting portion for a reinforcing member is provided at a portion offset forward and downward from the support center of the front support portion of the left and right suspension arms,
A front sub-frame structure characterized in that a reinforcing member for linearly connecting the left and right connecting portions in the vehicle width direction is provided. The front sub-frame includes a cross member main body provided with a front support portion of the suspension arm and a connecting portion for the reinforcing member,
The front sub-frame structure according to claim 1, further comprising a side member extending forward from the left and right front ends of the cross member main body. The rear end portion of the reinforcing member is widened rearward to form a coupling portion for the suspension arm support bracket,
The front subframe structure according to claim 1 or 2, wherein the front edge of the reinforcing member is formed in a straight line extending in the vehicle width direction.

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