JP2009298186A - Underfloor structure for rear part of automobile body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To strengthen the rigidity of a connection position of left and right rear side members of a vehicle and a suspension arm and its periphery without receiving influence of a service hole provided in a floor. <P>SOLUTION: In the underfloor structure of the vehicle body rear part for the automobile, the service hole 20 is formed on a floor panel 2a just above a fuel pump 50 of a fuel tank 5 installed below it and a front end of the suspension arm 4 is connected to left and right rear side members 3 at both left and right sides of the service hole 20. Cross members 6A, 6B linearly laid between the left and right rear side members 3 are provided on a lower surface of the floor panel 2a at front and rear positions of the service hole 20, and a vertical brace 7 laid between both cross members 6A, 6B is installed between the front and rear cross members 6A, 6B at both left and right side positions of the service hole 20. The connection position of the rear side member 3 and the vertical brace 7 are connected by a lateral brace 8 in a vehicle width direction respectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an underfloor structure at the rear of a vehicle body of an automobile, in particular, an underfloor structure in which a suspension arm of a rear suspension is connected to the left and right rear side members, and the rigidity of the rear of the vehicle body in which a fuel tank is installed between the left and right connection positions. About.

  As shown in FIG. 4, conventionally, a pair of left and right rear side members 3, 3 extending rearwardly along the lower surface of the floor panel 2 from the rear ends of the left and right rockers 1, 1, respectively, below the floor at the rear of the vehicle body. The front ends of the rear suspension suspension arms 4 and 4 that support the rear wheels R and R are connected to the front portions of the rear side members 3 and 3, and a fuel is provided between the front ends of the left and right rear side members below the floor at the rear of the vehicle body. There is a structure in which a tank 5 is installed and a service hole 20 penetrating a floor panel is formed for maintenance of the fuel pump 50 at a position directly above the fuel pump 50 provided on the upper surface of the fuel tank 5.

By the way, inputs such as vibrations from the rear wheels R and R act on the connecting positions T and T between the rear side members 3 and 3 and the suspension arms 4 and 4 when the vehicle travels. In particular, when the vehicle turns a curve, when the left and right vibration inputs act on both the connecting positions T and T, and the distance between the both connecting positions T and T changes, the running stability of the vehicle decreases.
For this reason, in order to reinforce the rigidity of the left and right connecting positions T and T and the periphery thereof, as shown in Patent Document 1, a cross member is provided between the vicinity of the connecting positions T and T of the left and right rear side members in the vehicle width direction. It is being constructed.
JP-A-6-24353

However, as shown in FIG. 4, in a vehicle in which the service hole 20 is installed between the connection positions T, T between the left and right rear side members 3, 3 and the suspension arms 4, 4, the cross member 9 is connected to the left and right connection positions. The cross member 9 cannot be bridged in a straight line between them, and the cross member 9 has a substantially angled bent shape in plan view, avoiding the service hole 20. However, the bent cross member 9 has a problem in that the left and right vibration inputs acting on the connecting positions T and T cannot be effectively suppressed, and both ends must be thickened.
Therefore, the present invention provides the rigidity of the connection position and its periphery, particularly the rigidity in the left-right direction, without interfering with workability in the service hole formed in the floor between the connection positions of the left and right rear side members and the suspension arm. An object of the present invention is to provide an underfloor structure at the rear of the vehicle body that can be strengthened and improves the running stability of the vehicle.

In the present invention, a fuel tank is installed on the lower surface of the floor panel under the floor at the rear of the vehicle body, a service hole penetrating the floor panel is formed at a position directly above the fuel pump of the fuel tank, and left and right of the floor panel The left and right rear side members extending back and forth along the side edges are connected to the front ends of the left and right suspension arms of the rear suspension at the left and right sides of the fuel tank. The front and rear cross members are provided in a straight line between the left and right rear side members along the lower surface of the floor panel, and the front and rear cross members are provided on the lower surface of the floor panel at both the left and right positions of the service hole. Install a pair of left and right vertical braces across the cross members And a vertical brace of the suspension arm connecting position and the right and left rear side members, respectively, allowed to linking the lateral braces in the vehicle width direction along the lower surface of the floor panel (claim 1).
According to this, with respect to the vibration input acting on the connection position of the rear side member and the suspension arm, the vertical brace laid between the front and rear cross members and the horizontal brace connected to the connection position are supported. The rigidity at the connection position and its periphery is enhanced.

Corresponding to the left and right rear side members and the front and rear cross members that form a closed cross section with the floor panel, the left and right vertical braces and the left and right horizontal braces are formed in reverse hat shapes, respectively, and the closed cross section is formed with the floor panel. (Claim 2).
By making the vertical brace and the horizontal brace have a closed cross-sectional structure, it is optimal for strengthening the rigidity of the connection position between the rear side member and the suspension arm and its periphery.

On the lower surface of the left and right rear side members, left and right side walls of the rear side member are extended downward, and a support bracket having a pair of left and right vertical walls facing each other with a space therebetween is installed. The front end of the suspension arm is connected and supported by a support shaft that penetrates both vertical walls horizontally, and the lower edge of the vertical wall on the inside of the support bracket and the lower surface of the horizontal brace are supported by a reinforcing plate. It connects (Claim 3).
By supporting the support bracket that protrudes downward from the rear side member and supports the suspension arm with a reinforcing plate from the inside of the vehicle, the rigidity of the support bracket against vibration input can be enhanced.

The vertical brace is provided at a position where a leg portion of a rear seat installed on the upper surface of the floor panel is connected to the floor panel, and the rear seat connecting position of the floor panel is reinforced by the vertical brace.
There is no need to provide a dedicated reinforcing member for reinforcing the connecting position of the floor panel to the leg portion of the rear seat.

An embodiment in which the present invention is applied to an underfloor structure at the rear of a vehicle body of a van type vehicle having a luggage compartment formed at the rear of the passenger compartment will be described.
As shown in FIG. 1, a pair of left and right rear side members 3, 3 extending rearward along the lower surface of the floor panel 2 from the inside of the rear end of the left and right rockers 1, 1 are provided below the floor at the rear of the vehicle body. It is. Cross members 6A and 6B are installed between the front ends of the rear side members 3 and 3 and between the intermediate positions in the vehicle width direction.
Both rear side members 3 and 3 are provided with support brackets 40 and 40 at their front ends, to which the front ends of a pair of left and right suspension arms 4 of the rear suspension for supporting the rear wheels R and R are connected.

As shown in FIGS. 1 and 2, the left and right rear side members 3, 3 are formed by connecting the tapered outer sides of the front ends along the side surfaces of the rear ends of the rockers 1, 1. The rear side members 3, 3 extend from the coupling position with the rockers 1, 1 in an obliquely upward direction and are provided at a position one step higher than the rockers 1, 1.
Corresponding to the rear side members 3 and 3 that are one step higher, in the floor panel 2, the panel rear portion 2a that forms the cargo compartment is made one step higher than the panel front portion 2b that forms the passenger compartment, and the panel rear portion 2a and the panel front portion 2b An inclined step 2c is formed between the two.
The rear side members 3 and 3 have a reverse hat shape in cross section, and the upper edge flanges on both the left and right sides are coupled to the lower surface of the floor panel 2 to form a closed cross section with the floor panel 2.

  A fuel tank 5 is installed at a lower position on the front side of the panel rear portion 2 a of the floor panel 2. In addition, a service hole 20 for maintenance of the fuel pump 50 is formed in the panel rear portion 2a so as to pass through substantially the center in the vehicle width direction of the panel rear portion 2a corresponding to the fuel pump 50 provided in the center of the upper surface of the fuel tank 5. It is formed. The service hole 20 is positioned between the front and rear cross members 6A and 6B to match the connection position of the left and right rear side members 3 and 3 and the suspension arms 4 and 4. Normally, the service hole 20 is closed with a cover 21.

  The front and rear cross members 6A and 6B are set at the front and rear positions of the service hole 20. The front cross member 6A is installed along the boundary between the panel rear portion 2a and the stepped portion 2c, has a substantially L-shaped cross section, and the front edge and the rear upper edge are the lower surface side of the stepped portion 2c and the lower surface of the panel rear portion 2a, respectively. Connected to the side to form a closed section. The cross member 6B on the rear side has an inverted hat shape in cross section, and the upper edge flanges on both sides are coupled to the lower surface of the panel rear portion 2a to form a closed cross section with the panel rear portion 2a. The left and right ends of the cross members 6A and 6B are respectively coupled to the side surfaces of the left and right rear side members 3 and 3 on the vehicle inner side.

  A rear seat S is installed above the front side of the panel rear portion 2a. The rear seat S connects the lower end of the front leg S1 provided at the front end of the seat cushion to the panel front portion 2c so as to be able to tilt in the front-rear direction, and a latch mechanism S2 serving as a leg provided at the rear end of the seat cushion. The panel rear part 2a is detachably engaged with the panel. The rear seat S is disengaged from the panel rear portion 2a by the latch mechanism S2, and can be retracted forward about the base end of the front leg S1 and stored in the panel front portion 2c side.

The connection position of the rear side member 3 and the suspension arm 4 and the surrounding underfloor structure will be described with reference to FIGS. 1 to 3, particularly FIGS. 2 and 3. The underfloor structure is a left-right symmetrical structure, and the structure on one side will be mainly described.
The support bracket 40 for connecting the suspension arm 4 to the rear side member 3 is a press-molded product made of a metal plate, and left and right vertical walls 41 facing each other at intervals so as to extend the left and right side surfaces of the rear side member 3 downward. 42 and a front wall connecting the front ends of both vertical walls 41 and 42 have a substantially U-shaped horizontal cross section that opens rearward, and is fixed to the lower surface of the rear side member 3 so as to protrude downward. The vertical wall 42 on the vehicle outer side of the support bracket 40 is superimposed on the side surface on the vehicle inner side of the rocker 1 lower than the rear side member 3.

  The support bracket 40 pivotally supports a vibration isolating member 45 provided at the front end of the suspension arm 4 by a support shaft 44 that extends horizontally between the left and right vertical walls 41 and 42 in a vertical direction. It is connected so that it can swing. The suspension arm 4 is made of a thick metal pipe and supports the rear wheel R at the rear end.

  On the lower surface of the panel rear portion 2a of the floor panel 2, a vertical brace 7 is installed at a position near the service hole 20 so as to bridge between the front and rear cross members 6A and 6B. The vertical brace 7 is formed in an inverted hat shape in cross section, and the left and right upper edge flanges are coupled to the lower surface of the panel rear portion 2a to form a closed cross section with the panel rear portion 2a. Terminals before and after the vertical brace 7 are respectively coupled to the rear surface of the front cross member 6A and the front surface of the rear cross member 6B.

  The vertical brace 7 is installed at a position corresponding to the latch mechanism S2 of the rear seat S, and a striker 23 is bolted to the upper surface of the panel rear portion 2a at a position directly above the vertical brace 7, The latch mechanism S2 is detachably engaged.

  Further, a horizontal brace 8 is bridged between the connecting position of the rear side member 3 and the suspension arm 4 and the vertical brace 7 in the vehicle width direction on the lower surface of the panel rear portion 2a. Similar to the vertical brace 7, the horizontal brace 8 has an inverted hat shape in cross section, and the front and rear upper edge flanges are coupled to the lower surface of the panel rear portion 2a to form a closed cross section structure with the panel rear portion 2a. A terminal on the inner side of the lateral brace 8 is connected to a front and rear intermediate position on the outer side surface of the vertical brace. The end of the lateral brace 8 on the vehicle outer side is enlarged in height and width in accordance with the height of the rear side member and the front / rear width of the support bracket 40. The upper wall 41 is integrally coupled to the upper portion of the vertical wall 41.

  Further, the lateral brace 8 is provided with a reinforcing plate 80 that connects this to the support bracket 40. The reinforcing plate 80 is made of a metal plate having a shallow cross-sectional hat shape. One end is bolted to the lower end of the vertical wall 41 of the support bracket 40, and the other end is bolted to an intermediate position on the lower surface of the horizontal brace 8. And the horizontal brace 8 are connected in an inclined manner.

  According to the present embodiment, the left and right rear side members 3 are connected by linear front and rear cross members 6A and 6B at the front and rear positions of the service hole 20, and the cross members 6A and 6B are The left and right vertical braces 7 are connected to the suspension arms 4 of the left and right rear side members 3 by the horizontal braces 8 respectively, so that the suspension arms 4 of the left and right rear side members 3 are connected to each other. The rigidity in the left-right direction around the connecting position and the periphery thereof is greatly enhanced. Therefore, even when the vehicle turns sharply, the running stability is ensured without changing the distance between the connection positions of the left and right rear side members 3 with the suspension arm 4.

In the structure in which the front end of the suspension arm 4 is connected to the support bracket 40 provided on the lower side of the rear side member 3, the vertical wall 41 on the vehicle interior side of the support bracket 40 and the horizontal brace 8 are connected by the reinforcing plate 80. The rigidity of the connecting portion of the rear side member 3 to the suspension arm 4 and the periphery thereof is sufficiently ensured.
Further, since the front and rear cross members 6A and 6B and the left and right vertical braces 7 are positioned so as to surround the service hole 20 of the floor panel 2 and do not cross the service hole 20, workability in the service hole 20 is not hindered.
Further, since the vertical brace 7 is provided at the connection position with the floor panel of the rear seat, the connection position is reinforced, and there is no need to provide a dedicated member for reinforcing the connection position.

It is a schematic plan view which shows the underfloor structure of the vehicle body rear part of this invention. It is sectional drawing which follows the II-II line of FIG. It is sectional drawing which follows the III-III line of FIG. It is a schematic plan view of the conventional underfloor structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rocker 2 Floor panel 2a Panel rear part 20 Service hole 3 Rear side member 4 Suspension arm 40 Support bracket 41, 42 Vertical wall 44 Support shaft 5 Fuel tank 50 Fuel pump 6A, 6B Cross member 7 Vertical brace 8 Horizontal brace 80 Reinforcement plate S Rear seat S2 Latch mechanism (leg)

Claims (4)

A fuel tank is installed on the lower surface of the floor panel under the floor at the rear of the vehicle body. A service hole that penetrates the floor panel is formed immediately above the fuel pump of the fuel tank, and along the left and right side edges of the floor panel. In the underfloor structure at the rear of the vehicle body of the automobile, the left and right rear side members that extend back and forth are connected to the front ends of the left and right suspension arms of the rear suspension at the left and right positions of the fuel tank.
Front and rear cross members are provided at the front and rear positions of the service hole along the lower surface of the floor panel in a straight line between the left and right rear side members. A pair of left and right vertical braces are installed at the position along the lower surface of the floor panel between the cross members, and the connection position of the left and right rear side members with the suspension arm and the left and right vertical braces, respectively, An underfloor structure at the rear of a vehicle body, characterized by being connected by a lateral brace in the vehicle width direction along the lower surface of the floor panel.   Corresponding to the left and right rear side members and the front and rear cross members that form a closed cross section with the floor panel, the left and right vertical braces and the left and right horizontal braces are formed in reverse hat shapes, respectively, and the closed cross section is formed with the floor panel. The underfloor structure of the rear part of the vehicle body of the automobile according to claim 1 formed. On the lower surface of the left and right rear side members, left and right side walls of the rear side member are extended downward, and a support bracket having a pair of left and right vertical walls facing each other with a space therebetween is installed. The front end of the suspension arm is connected and supported by a support shaft that penetrates both vertical walls horizontally.
The underfloor structure of the rear part of the vehicle body of an automobile according to claim 2, wherein a lower edge of a vertical wall inside the support bracket and a lower surface of the horizontal brace are connected by a reinforcing plate.   4. The automobile according to claim 1, wherein the vertical brace is provided at a position where a leg portion of a rear seat installed on the upper surface of the floor panel is connected to the floor panel, and the rear seat connecting position of the floor panel is reinforced by the vertical brace. Underfloor structure at the rear of the car body.

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