JPH0733986Y2 - Vehicle body structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a body structure of a connecting portion between a floor panel and a dash panel.

(Prior Art) Generally, in this type of body structure, as schematically shown in FIG. 5, a front end portion of a floor panel (A) and a lower end portion of a dash panel (B) are connected to each other, and At the binding site of panels (A) and (B), both of these panels (A)
A cross member (C) having a U-shaped cross section which is connected to (B) and extends over substantially the entire length in the vehicle width direction is provided, and the panels (A) (B) and the cross member (C) have a closed cross section. Of the cross member (C)
Attach the support bracket (D) to the middle of the
The support bracket (D) elastically supports the engine.

By the way, in the vehicle having the above-mentioned body structure, as is apparent from FIG. 5, the support point (P) of the engine with respect to the support bracket (D) is located in front of the cross member (C) due to reasons such as assemblability. It is generally offset in the left direction (FIG. 5), so that the skeleton having a closed cross section composed of the cross member and the front end portion of the floor panel is caused by the vibration accompanying the engine driving. The floor bracket (A) oscillates in the torsional direction (direction of arrow X in FIG. 5) through the support bracket, especially in the middle portion in the longitudinal direction, causing a corrugated phenomenon in the floor panel (A), which causes muffled sound in the vehicle interior. .

When the frequency of driving the engine coincides with the natural frequency of the skeleton formed by the cross member and the front end of the floor panel, a so-called resonance phenomenon occurs in which the vibration increases, and the vehicle interior Since the muffled noise becomes very loud, such a resonance phenomenon occurs in the normal engine speed range (for example, 4000 rpm) of the conventional body structure described above.
rpm) often occurs.

The present invention has been developed in view of the above circumstances. The object of the present invention is to make the natural frequency of the skeleton having a closed cross-section composed of the cross member and the floor panel the normal frequency of an engine with an extremely simple structure. It is intended to provide a body structure which can be outside the range of the rotational speed and at the same time can sufficiently enhance the rigidity of the skeleton.

(Means for Solving the Problems) The present invention, however, connects the front end of the floor panel and the lower end of the dash panel, and the upper wall and the lower wall facing each other at the connecting portions of these panels. A cross member extending in the vehicle width direction having a front wall that connects the front ends of the upper wall and the lower wall is assembled, and a skeleton having a space with a closed cross section is formed by the both panels and the cross member. A vehicle in which a support bracket of an engine is bolted to an intermediate portion in the longitudinal direction of the cross member, wherein an upper facing wall and a lower facing wall overlap with an upper wall and a lower wall of the cross member in the closed space, respectively. A front side wall connecting the front end portions of the upper facing wall and the lower facing wall, and left and right side walls connecting the left and right ends of the upper facing wall and the lower facing wall,
A box body having an upper facing wall and a rear side wall connecting the rear ends of the lower facing walls is formed, and the box body is fixed to the middle portion in the longitudinal direction of the cross member in the closed space. The upper and lower walls of the cross member and the upper and lower opposite walls of the box body overlapping the upper and lower walls are provided with bolt insertion holes, and the mounting bracket mounting bolts are inserted into the insertion holes and the bolt insertion ends. A nut is screwed to the portion to fix the support bracket to the cross member.

(Operation) According to the present invention, the vibration from the driving of the engine causes the input from the support bracket of the engine to act on the intermediate portion in the longitudinal direction of the cross member via the bolt, so that the closed space tends to collapse. Also, in the closed space, the box body interposed between the upper and lower walls of the cross member prevents deformation of the upper and lower walls of the cross member and prevents collapse of the closed space. Of the skeleton formed by the floor panel and the cross member, the rigidity of the middle portion in the vehicle width direction where vibration is particularly large is sufficiently increased, so that the vibration of the skeleton is reduced and the natural frequency of the skeleton is determined by the engine. Can be set outside the range of the normal rotation speed, and in the normal rotation range of the engine, resonance of the skeleton due to vibration of the engine can be suppressed.

Embodiment An embodiment of the body structure according to the present invention will be described below with reference to the drawings.

The schematic cross-sectional view of FIG. 1 shows a boundary portion between a vehicle compartment and an engine room in a sedan-type automobile. In the figure, (1) is a dash panel that divides the vehicle room (R1) and the engine room (R2), Reference numeral 2) is a floor panel forming a floor with a passenger compartment (R1), and a sloped wall portion (21) extending obliquely upward is provided at a front end of the floor panel (2).
The free end of 1) is fixed to the lower end of the dash panel (2) by welding.

Further, (3) is a cross member having a substantially U-shaped cross section that extends over substantially the entire length in the vehicle width direction.
As shown in FIG. 3, the lengthwise intermediate portion is bent upward as viewed from the front so that a floor tunnel is formed below the lengthwise intermediate portion of the cross member (3). ing.

The hanging cross member (3) has the upper and lower walls (31) facing each other.
(32) and a front wall (33) that connects the front ends of the upper and lower walls (31) (32), and the rear end of the upper wall (31) is connected to the dash panel (1) and the floor panel (2). ) And the rear end of the lower wall (32) is connected to the front end of the floor panel (2) at the same time, and the cross member (3) and the floor panel (2) are inclined. The wall portion (21) and the wall portion (21) form a skeleton including a space (S1) having a closed cross section that extends over substantially the entire length in the vehicle width direction.

Further, (4) is a support bracket for elastically supporting an engine (not shown) on the vehicle body, and the support bracket (4) is provided with a bolt (41) at a middle portion in the longitudinal direction of the cross member (3). ) And a nut (42).

The engine support point (P) of the support bracket (4) is located in front of the cross member (3) (first position).
Offset to the left in the figure).

In the embodiment shown in the figure, the second configuration
As shown in the figure, it comprises a box-shaped box body (50) having an opening at the rear, and a closing plate (51) for closing the opening of the box body (50). By being fixed by welding to the opening edge of (50), the upper facing wall ((1) overlaps with the inner surfaces of the upper wall (31) and the lower wall (32) of the cross member (3) in the closed space (S1), respectively. 5a) and the lower facing wall (5b),
A front side wall (5c) connecting the front ends of the upper facing wall (5a) and the lower facing wall (5b), and left and right side walls connecting the left and right ends of the upper facing wall (5a) and the lower facing wall (5b). (5d) and a rear side wall (5e) that connects the rear ends of the upper facing wall (5a) and the lower facing wall (5b), and the inside is a closed space (S2) independent of the closed space (S1). ), A rectangular parallelepiped box body (5) is formed, and the box body (5) is fitted to the inner surface of the cross member (3) in the longitudinal direction in the closed space (S1). The box body (5) is fixed to the cross member (3) by welding, and by assembling the box body (5), the cross member (3) and the inclined wall portion (21) of the floor panel (2). The natural frequency of the skeleton (6) composed of
m) is the engine frequency that occurs when the engine is rotating, and the upper and lower walls (31) of the cross member (3)
Bolt insertion holes (6) are provided in the upper and lower opposing walls (5a) and (5b) of the box body (5) which overlaps with (32) and the upper and lower walls (31) and (32).

Then, the mounting bolts (4
1) is inserted into the insertion hole (6) and the bolt (4
The support bracket (4) is fixed to the middle portion in the longitudinal direction of the cross member (3) incorporating the box body (5) by screwing the nut (42) at the insertion end of 1). Of.

Incidentally, (43) in the figure shows a collar inserted through the bolt (41).

In the above body structure, the skeleton (6) vibrates in the direction of the arrow X in FIG. 1 via the support bracket (4) due to the vibration associated with engine driving, and particularly in the middle of the skeleton (6) in the longitudinal direction. Part, ie said support bracket (4)
The mounting part of the box tends to vibrate greatly, and the box body (5) having the closed space (S2) independent of the closed space (S1) is incorporated in the part, and the closed space is Since the (S1) and the closed space (S2) are configured, the rigidity of the middle portion in the length direction of the skeleton (6) is sufficiently enhanced, and thus the middle portion in the length direction of the skeleton (6). The vibration of the part is suppressed.

That is, the vibration from the driving of the engine causes the input from the support bracket (4) to act on the intermediate portion in the longitudinal direction of the cross member via the bolt, thereby causing the closed space (S
Even if 1) is about to collapse, the box body (5) interposed between the upper and lower walls of the cross member (3) in the closed space (S1) prevents the cross member (3) from being deformed. Then, the collapse of the closed space (S1) is prevented.

Further, due to the assembly of the box body (5) to the skeleton (6), the skeleton (6) is kept within the normal engine speed range of the engine.
There is no possibility of resonance. Therefore, the waving phenomenon of the floor panel (2) is also suppressed, and the muffled noise in the passenger compartment is reduced accordingly.

Then, FIG. 4 shows the data obtained by measuring the muffled sound in the passenger compartment. In the figure, the alternate long and short dash line shows the case of the conventional body structure without the reinforcement (5), and the solid line shows the reinforcement ( FIG. 5 shows the case of the above-described embodiment including 5), and as is clear from such data, the automobile having the structure of the embodiment can reduce the muffled noise generated in the vehicle interior. Moreover, it can be seen that, in the related art, the engine rotation speed at which the muffled sound in the vehicle interior becomes high due to the resonance of the skeleton is particularly reduced at around 4000 rpm.

(Effects of the Invention) As described above, according to the present invention, the front end of the floor panel and the lower end of the dash panel are connected to each other, and the upper and lower walls facing each other and the upper wall and A cross member extending in the vehicle width direction having a front wall connecting the front ends of the lower walls is assembled, and a skeleton having a space with a closed cross section is formed by the both panels and the cross member,
In a vehicle in which a support bracket of an engine is bolted to an intermediate portion in the longitudinal direction of the cross member, an upper facing wall and a lower facing wall that overlap with an upper wall and a lower wall of the cross member in the closed space, respectively. A front side wall connecting the front ends of the upper facing wall and the lower facing wall, left and right side walls connecting the left and right ends of the upper facing wall and the lower facing wall, and a rear end of the upper facing wall and the lower facing wall. A box body having a rear side wall to be connected is formed, and the box body is
The support bracket is fixed to the middle portion in the lengthwise direction of the cross member in the closed space, and bolt insertion holes are provided in the upper and lower walls of the cross member and the upper and lower opposite walls of the box body overlapping the upper and lower walls. The mounting bolt of 1 is inserted into the insertion hole, the nut is screwed into the insertion end of the bolt, and the support bracket is fixed to the cross member. Even if the input from the bracket acts on the intermediate portion in the longitudinal direction of the cross member via the bolt to collapse the closed space, it is interposed between the upper and lower walls of the cross member in the closed space. The box body that is present can prevent the cross member from being deformed and prevent the closed space from collapsing, and further, the floor panel. Wherein the rigidity in the vehicle width direction intermediate portion, in particular vibration occurs greatly among the composed skeleton cross member is increased sufficiently, to vibration of the skeleton is reduced,
It is also possible to set the natural frequency of the skeleton outside the range of the normal engine speed of the engine to suppress the resonance of the skeleton due to the vibration of the engine, and thus to suppress the waving phenomenon of the floor panel and The muffled sound can be reduced to that extent.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of a body structure according to the present invention, FIG. 2 is a schematic perspective view showing an exploded cross member and a box body, and FIG. 3 is a schematic front view of the cross member. FIG. 4 is an explanatory view showing a result of measuring the muffled sound in the vehicle compartment, and FIG. 5 is a schematic sectional view showing an example of a conventional body structure. (1) …… Dash panel (2) …… Floor panel (3) …… Cross member (31) …… Upper wall (32) …… Lower wall (4) …… Support bracket (41) …… Bolt (42) ) …… Nut (5) …… Box body (5a) …… Upper facing wall (5b) …… Lower facing wall (5c) …… Front side wall (5d) …… Left and right side walls (5e) …… Rear side wall ( 6) …… Insertion hole

Claims (1)

[Scope of utility model registration request] 1. A front end portion of a floor panel and a lower end portion of a dash panel are connected to each other, and upper and lower walls facing each other and front ends of the upper wall and the lower wall are connected to connecting portions of these panels. A cross member having a front wall and extending in the vehicle width direction is assembled to form a skeleton having a space with a closed cross-section by the both panels and the cross member, and a longitudinal intermediate portion of the cross member. In a vehicle in which a support bracket of an engine is bolted to, an upper facing wall and a lower facing wall that overlap with an upper wall and a lower wall of the cross member in the closed space, and the upper facing wall and the lower facing wall, respectively. A box provided with a front side wall connecting the front ends of the two, left and right side walls connecting the left and right ends of the upper facing wall and the lower facing wall, and a rear side wall connecting the rear ends of the upper facing wall and the lower facing wall. Shape the body Then, the box body is fixed to the middle portion in the longitudinal direction of the cross member in the closed space, while the upper and lower walls of the cross member and the upper and lower opposite walls of the box body overlapping with the upper and lower walls are provided with bolts. An insertion hole is provided, a mounting bolt of the support bracket is inserted into the insertion hole, and a nut is screwed to an insertion end portion of the bolt to fix the support bracket to the cross member. The body structure of the vehicle.