JPH04349080A - Under-body structure of car - Google Patents

Abstract

PURPOSE:To compatibly provide the original function to work as a tunnel member and a function to allow the load affected part to shrink in the event of frontal collision of a car. CONSTITUTION:A tunnel member 11 is set over the left and the right under-part of the tunnel part 8a of a car. That area of this tunnel member 11 which mates with the under-side of a propeller shaft 4 is configured with a plurality of frame parts 11b, 11c divided to the front and rear, and these frame parts 11b, 11c are arranged with a level difference. This secures the function to suppress deformation of the tunnel part 8a in the direction of opening, and it is possible to admit downward movement by folding the frame parts 11b, 11c with a time difference with the propeller shaft 4 which moves downward with the load due to frontal collision.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lower body structure of a vehicle, and more particularly to a tunnel member provided in a tunnel portion of a floor panel.

0002

[Prior Art] Conventionally, for example, Japanese Patent Application Laid-Open No. 56-280
In FR (front engine/rear drive) vehicles such as those shown in Publication No. 53, the driving force from the engine mounted at the front of the vehicle body is transferred to a differential gear located between the left and right rear wheels. A propeller shaft is provided for transmission. In order to accommodate the propeller shaft, the floor panel constituting the floor surface of the vehicle compartment has a substantially U-shaped cross-sectional shape that bulges upward at the center in the vehicle width direction and opens downward. A tunnel portion is formed. In addition, in order to restrict the deformation of the lower end of this tunnel part in the opening direction (outward in the vehicle width direction) and to ensure a predetermined cross-sectional shape of this tunnel part, a tunnel member is installed between the lower end part of the tunnel part. There are some that have been constructed.

[0003] On the other hand, a plurality of universal joints are interposed in the propeller shaft, making it possible to transmit driving force even if the relative position between the engine and the differential gear changes. In the event of a frontal collision of a vehicle, when the frontal collision load acts on the engine and causes the engine to move rearward, the propeller shaft moves the universal joint to the corner point due to this movement. By moving the frontal collision force downward, the front collision load is prevented from being transmitted to the differential gear.

0004

[Problems to be Solved by the Invention] However, in a vehicle equipped with a tunnel member as described above, this tunnel member has high rigidity in order to restrict deformation of the tunnel portion, and therefore, the front of the vehicle as described above has a high rigidity. There has been a problem in that when the propeller shaft moves downward due to an accident, the propeller shaft may come into contact with the tunnel member and its downward movement may be restricted. However, forming the tunnel member with a material with low rigidity is
This is not preferable because the original function of the tunnel member, which is to suppress deformation of the tunnel portion in the opening direction, will be impaired.

The present invention has been made in view of these points, and it is an object of the present invention to obtain a tunnel member that is capable of achieving both the original function of the tunnel member and the reduction operation of the load-affected part in the event of a frontal collision of a vehicle. With the goal.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention has a structure that allows the tunnel member to bend downward while ensuring a sufficient cross-sectional area. Specifically, the present invention assumes a lower body structure of a vehicle in which a floor panel is provided with a tunnel portion that bulges upward and extends in the longitudinal direction of the vehicle body, and a propeller shaft is disposed within the tunnel portion. . Then, a tunnel member is constructed between the left and right lower portions of the tunnel portion,
A portion of the tunnel member corresponding to the lower side of the propeller shaft is constituted by a plurality of frame portions divided in the front-rear direction, and each of the frame portions is arranged with a step in the vertical direction. It was structured like this.

[0007]

[Operation] With the above structure, in the present invention, when the propeller shaft moves downward due to the frontal collision load in the event of a frontal collision of the vehicle, the propeller shaft abuts each frame portion in turn, with a time difference. Move downward while bending each frame part downward one by one. In other words, since the rigidity of each frame part is lowered one by one, the propeller shaft can be easily moved downward. In addition, since the original function of a tunnel member, which is to suppress deformation in the opening direction of the tunnel section, is governed by the total cross-sectional area of the longitudinal sections of each frame section, the Even if the cross-sectional area is small, the total cross-sectional area can be secured to an extent that sufficiently suppresses deformation of the tunnel portion in the opening direction.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the vehicle 1 of this example is a so-called FR vehicle with a front engine and rear drive.
The engine 2 includes a propeller shaft 4 extending rearward from a transmission 3 disposed on the rear side of the engine 2, and the propeller shaft 4 is connected to a differential gear 5 disposed between left and right rear wheels (not shown). Additionally, universal joints 6 and 7 are interposed at two locations near the front and rear ends of the propeller shaft 4, and these universal joints 6 and 7 connect the transmission 3 and differential gear 5 when the vehicle is running. The driving force of the engine 2 is transmitted to the differential gear 5 even if the relative position with respect to the engine 2 changes. Also, vehicle 1
In the event of a frontal collision, when the frontal collision load acts on the engine 2 and transmission 3 and causes them to move rearward, the propeller shaft 4 bends from the universal joints 6 and 7 and moves downward. However, the amount of rearward movement of the engine 2 and transmission 3 is converted into downward movement, so that the frontal collision load is not transmitted to the differential gear 5 or the rear wheels.

As shown in FIG. 3, a floor panel 8 forming the floor surface of the vehicle compartment has an upwardly extending portion in the vehicle interior direction in the center portion in the vehicle width direction to accommodate the propeller shaft 4. A tunnel portion 8a is provided which has a substantially U-shaped cross section that bulges out and opens downward. Further, a power plant frame 9 is disposed within this tunnel portion 8a. This power plant frame 9 is made of a plate bent into a substantially U-shape when viewed from the front so as to cover the upper, lower and left sides of the propeller shaft 4, and the front end is connected to the transmission 3 and the rear end is connected to the differential. gear 5
The bending rigidity of the tunnel portion 8a is improved by being connected to the tunnel portions 8a, respectively. Furthermore, an exhaust pipe 10 is disposed below the propeller shaft 4 within this tunnel portion 8a. In addition, in FIG. 2, 10a
is a catalytic converter, and 10b is a muffler.

Next, the structure around the rear end of this vehicle will be explained. As shown in FIG. 4, a trunk room 13 is formed at the rear end of the vehicle by a trunk floor panel 8b, which is the rear part of the floor panel 8. The trunk floor panel 8b has a spare tire accommodating portion 8c formed by recessing the right side portion of the vehicle body downward, and a fuel tank 14 is disposed below the spare tire accommodating portion 8c. Further, on the front side of the spare tire storage portion 8c, a cross member 15 having a substantially hat-shaped cross section that is open upward is provided on the back surface of the trunk floor panel 8b, and extends in the vehicle width direction between the cross member 15 and the trunk floor panel 8b. It has a closed cross-section structure. On the other hand, a cross member 16 having a substantially hat-shaped cross section and opening toward the rear of the vehicle body is disposed below the rear end of the trunk floor panel 8b, and this cross member 16 has a substantially hat-shaped cross section that opens toward the rear of the vehicle body. A closed cross-sectional structure extending in the vehicle width direction is formed between the rear end panel 13a and the rear end panel 13a that constitutes the rear wall of the frame 13. Further, a rear center frame 17 is attached to the back surface of the trunk floor panel 8b on the left side of the spare tire storage portion 8c. The rear center frame 17 has its front end joined to the rear end surface of the cross member 15, and its rear end joined to the upper surface of the cross member 16, respectively. The rear center frame 17 has a substantially hat-shaped cross section with its front and rear ends open upward, and is connected to the lower surface of the trunk floor panel 8b, while the side of the spare tire storage section 8c is connected to the lower surface of the trunk floor panel 8b. The portion located on the side is cut out along the shape of the spare tire storage portion 8c, and is formed into a substantially L-shaped cross section as shown in FIG. They are respectively joined to the side surfaces of the vertical wall forming the portion 8c. As a result, the rear center frame 17 and the trunk floor panel 8b form a closed cross-sectional structure extending in the longitudinal direction of the vehicle body. Further, at the rear end of the rear center frame 17, a reinforcing gusset 18 with a U-shaped cross section that opens upward is installed extending from the lower surface of the cross member 16 to the lower surface of the rear center frame 17. Rigidity around the rear end of the rear center frame 17 is ensured. With this configuration, in the event of a rear collision of the vehicle, the rear collision load is input from the cross member 16 to the rear center frame 17, the rear center frame 17 absorbs the load, and the rear collision load is transferred to the fuel tank 14.
It is designed to suppress the impact on the inside of the vehicle. Further, in FIG. 4, 19 is a pair of left and right rear side frames, and 20 is a wheel house.

[0011]The feature of this embodiment is the tunnel member 11 installed between the left and right lower ends of the tunnel portion 8a. This tunnel member 11 is constructed by casting aluminum, and is shown in FIGS. 3 and 7.
As shown in FIG. 2, the tunnel portion 8a is bolted to support brackets 12, 12 joined to the lower left and right ends of the tunnel portion 8a, and the mounting portions 11a, 11a at both left and right ends, and the mounting portions 11
The first and second frame portions 11 formed between a and 11a
b, 11c. As shown in FIGS. 8 and 9, the mounting portion 11a has bolt holes 11d and 11d provided at two locations, front and rear, respectively.
Bolts B, B (see FIG. 7) are inserted into the support brackets 11d, so that the support brackets 12, 12, that is, are constructed between the left and right lower ends of the tunnel portion 8a. On the other hand, the first and second frame portions 11b and 11c have their left and right ends continuous with the mounting portion 11a, and are arranged in parallel with each other with a predetermined interval between them. and the first one located on the front side.
As shown in FIGS. 1 and 7, the frame material 11b is inclined obliquely upward from the vehicle body as it goes inward in the vehicle width direction from the front ends of the left and right mounting portions 11a, 11a, and its central portion extends horizontally. It has a generally elliptical cross section and is arranged in a straight line. On the other hand, the second frame material 11c located on the rear side is
The left and right mounting portions 11a, 11a are inclined diagonally downward from the rear end of the vehicle body as they go inward in the vehicle width direction, and the central portion thereof extends horizontally, and the first frame portion 11
It has a substantially elliptical cross section similar to that shown in b. In other words,
These first and second frame members 11b and 11c have a predetermined dimension in the longitudinal direction of the vehicle body, and have a slight step in the vertical direction so that they are partially overlapped when viewed from the front as shown in FIG. It is placed in a suitable position. The function of the tunnel member 11, which is the rigidity required to suppress the outward deformation of the tunnel portion 8a in the vehicle width direction, that is, the opening of the tunnel portion 8a, is controlled by the area of the longitudinal section of the tunnel member 11. In the above-mentioned structure, the total area of the vertical cross section of the first frame part 11b and the second frame part 11c is sufficiently secured to ensure deformation of the tunnel part 8a in the vehicle width direction. This is to prevent

[0012] Next, the operation of the above-mentioned structure at the time of a frontal collision of the vehicle will be explained. During a frontal collision of the vehicle, when the frontal collision load acts on the engine 2 and transmission 3 and causes the engine 2 and transmission 3 to move rearward, this movement causes the propeller shaft 4 to move between the universal joints 6 and 3. Move downward using 7 as the breaking point. As the propeller shaft 4 moves downward, the power plant frame 9 and exhaust pipe 10 are bent downward. And these are tunnel member 1
When it reaches the first arrangement position, it first comes into contact with the first frame part 11b located on the upper side. Since the first frame portion 11b has a small cross-sectional area, each deformable member 4, 10 moves downward while being bent. and,
Each of the deformable members 4 and 10 deforms further downward, and the second frame
When it reaches the position where the frame portion 11c is disposed, it comes into contact with the second frame portion 11c. Then, this second frame portion 11
Like the first frame portion 11b, the cross section c is also small, so it is bent downward. With such an operation, the front collision load is not transmitted to the differential gear 5 or the rear wheels, and the load-affected area can be reduced.

As described above, according to the configuration of this example, although the total cross-sectional area of the longitudinal cross-section of the tunnel member 11 is ensured large, the respective frame portions 11b and 11c are easy to break. While reliably preventing the tunnel portion 8a from deforming outward in the vehicle width direction, this load-affected portion can be reduced in the event of a frontal collision of the vehicle. Furthermore, since the first and second frame portions 11b and 11c are disposed at positions such that they partially overlap when viewed from the front, the height of the tunnel member 11 as a whole can be set small, and therefore, Since the height of the tunnel member 11 above the road surface can be set high, there is no concern that the tunnel member 11 will interfere with the road surface, and is highly practical.

Although the tunnel member 11 of this example has two frame parts, the first and second frame parts 11b and 11c, the present invention is not limited to this, and the present invention is not limited to this. The vehicle may be provided with frame portions, and may be arranged so as to be spaced from each other in the longitudinal direction of the vehicle body and to have a step in the vertical direction.

[0015]

As described above, according to the present invention, the tunnel member is provided with a plurality of frame sections, and each frame section is arranged with a step in the vertical direction. ,
Suppression of deformation in the opening direction of the tunnel section, which is controlled by the cross-sectional area of the longitudinal section of the tunnel member, is achieved by suppressing deformation in the opening direction of the tunnel section, even if the cross-sectional area of each frame section is small. In addition, in the event of a frontal collision of the vehicle, the propeller shaft moving downward contacts each frame part in turn with a time difference, causing each frame part to be sufficiently suppressed. Since the propeller shafts are moved downward while being bent one by one, the downward movement of the propeller shaft can be facilitated. In other words, it is possible to simultaneously suppress the deformation of the tunnel portion in the opening direction, which is the original function of the tunnel member, which could not be achieved in the past, and reduce the load-affected portion in the event of a frontal collision of the vehicle. Moreover, since each frame part is divided into front and back parts, the height of the tunnel member as a whole can be reduced by arranging the parts so that they partially overlap when viewed from the front.

[Brief explanation of drawings]

FIG. 1 is a side view showing a drive system of a vehicle.

FIG. 2 is a perspective view of the vehicle seen from below.

FIG. 3 is a sectional view taken along line III-III in FIG. 1;

FIG. 4 is a partially omitted perspective view showing the structure of the rear part of the vehicle body.

FIG. 5 is a sectional view taken along line V-V in FIG. 4;

FIG. 6 is a sectional view taken along line VI-VI in FIG. 4;

FIG. 7 is a longitudinal side view showing the vicinity of the tunnel member.

FIG. 8 is a plan view of the tunnel member.

FIG. 9 is a front view of the tunnel member.

[Explanation of symbols]

1 Vehicle 4 Propeller shaft 8 Floor panel 8a Tunnel section 11 Tunnel member 11b First frame part 11c Second frame part

Claims (1)

[Claims] 1. A lower body structure for a vehicle, wherein a floor panel is provided with a tunnel portion that bulges upward and extends in the longitudinal direction of the vehicle body, and a propeller shaft is disposed within the tunnel portion. A tunnel member is installed between the left and right lower portions of the propeller shaft, and the tunnel member is composed of a plurality of frame portions in which the portion corresponding to the lower side of the propeller shaft is divided in the front and back direction. 1. A lower body structure for a vehicle, wherein each frame portion is arranged with a step in the vertical direction.