JPH11208516A - Cab under frame structure of vehicle - Google Patents

Abstract

(57) [Summary] [Problem] A cab under of a vehicle having high welding strength, which has strength enough to withstand an impact force in a collision or the like, can absorb impact energy, can be implemented with a stable quality at a relatively low cost. It is intended to provide a frame structure. SOLUTION: The underframe intermediate portion 1 of a cab underframe 8 including an underframe front portion 3, an underframe intermediate portion 1, and an underframe rear portion 4 is formed by welding a plurality of frame members 2 having a closed cross section. Become. These mating portions are fixed by laser welding or the like. As a result, the middle portion 1 of the underframe has high rigidity, and the front portion 3 of the underframe is relatively low in rigidity. Become.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cab underframe structure of a vehicle suitable for reducing the deformation of a cab underframe by increasing the drag force of the kickup portion in a collision or the like.

[0002]

2. Description of the Related Art As shown in FIG. 7, a cab under frame 8 is provided below a cab 11 of a vehicle. The cab under frame 8 rises (kicks up) from the rear end of the under frame front portion 3a (shown by A) and the under frame front portion 3a disposed substantially horizontally on the front side.
An underframe intermediate portion 1a (indicated by B) and an underframe rear portion 4a (indicated by C) extending substantially horizontally rearward from the rising end of the underframe intermediate portion 1a. The cab under frame 8 is fixed to the lower surface of the floor panel 5 of the cab 11, the front side thereof is connected to the front mount rail 6, and the rear side is fixed to the rear mount rail 7.

As shown in FIG. 12, a large impact force acts on the cab underframe 8 at the time of a vehicle collision or the like. Therefore, in general, the cab underframe 8 of the cab-over vehicle may be bent with the base portion of the underframe intermediate portion 1a as a starting point as shown by a dotted line due to a kicked-up form of the cab undercarriage. May be deformed.

[0004]

In order to prevent the occurrence of the event shown in FIG.
11 is provided on the cab underframe 8. As shown in FIG. FIGS. 8 and 9 show a reinforcement member 9 having a substantially hat-shaped cross section.
Under frame front part 3a and under frame middle part 1
a. 10 and FIG.
In FIG. 1, a reinforcing member 10 formed by combining halved members is put on the middle portion 1a of the underframe and the rear portion 4a of the underframe to reinforce them.

On the other hand, there are various known techniques capable of reducing the deformation of the cab by retaining the strength of the frame and absorbing the impact energy at the time of a vehicle collision or the like. JP-A-5-2294
No. 52 publication. Japanese Unexamined Utility Model Publication No. 7-35252 discloses a “car frame structure” that includes a first intermediate wall connecting the upper wall and the lower wall inside a frame having a closed cross section surrounded by an upper wall, a lower wall, and both side walls. A technique is disclosed in which a frame is provided to connect the both side walls and to provide a second intermediate wall orthogonal to the first intermediate wall to reinforce the frame. With the above structure, it is possible to improve the strength of the frame at the time of collision or the like, and it is possible to improve the effect of being easy to manufacture and to be able to form a light weight.

On the other hand, Japanese Unexamined Patent Publication (Kokai) No. 5-229452 discloses a "vehicle body structure for a front part" in which a bead is provided on at least one of the front side member and the floor underline force at a joint thereof. When a force is applied to the member from the front of the vehicle body, the coupling portion is compressed and deformed to reduce the transmission of impact force to the front floor joined to the floor under reinforce and to reduce the deformation in the passenger compartment. is there.

The prior art shown in FIGS. 8 to 11 and the above-described known art have characteristics in the effect of maintaining the strength of the frame and absorbing the impact energy, respectively, but have the following problems. There is. That is, in any of the above-described prior arts, the joint between the frame and the reinforcing member must be welded. As this welding means, there are spot welding and various welding methods, but spot welding is desirable from the viewpoint of productivity. Therefore, in the prior art, spot welding is often used for welding the joints. However, in spot welding, it is necessary to apply a spot gun to both surfaces of a member to be welded, and in many cases spot welding cannot be performed depending on the shape of the member to be welded. Also,
Since spot welding is not continuous welding, there is a portion that cannot be welded between the spots of spot welding, and there is a possibility that the portion is deformed. On the other hand, it is desirable that the reinforcing means of the frame can be easily manufactured and can be implemented at low cost.

The present invention has been made in view of the above circumstances, and is relatively inexpensive and easy to carry out, and can stably maintain the strength of the frame at the time of impact and reduce deformation. It is an object of the present invention to provide a cab under frame structure.

[0009]

In order to achieve the above object, the present invention provides a structure of a cab underframe welded to the lower surface of a floor panel, wherein the structure is provided with a substantially horizontal underlay. A frame front portion, an underframe intermediate portion rising rearward from the rear end, and an underframe rear portion extending substantially horizontally rearward from the rear end, at least the underframe intermediate portion forms a frame member forming a closed cross section. A cab under frame structure of a vehicle comprising a plurality of welds.
Further, a joint portion between the underframe intermediate portion and the like formed of the frame member and the underframe front portion and the underframe rear portion, and a joint portion between the underframe front portion and the underframe rear portion and the floor panel are fixed by laser welding or the like. And Further, a plurality of the frame members are fixed to each other by laser welding or the like. Further, the frame member is formed of a hollow body having a rectangular cross section and is formed by a hydroforming method or the like.

An intermediate portion of the underframe, on which a large impact force acts upon a collision or the like, is formed by welding a plurality of closed-section frame members. When a plurality of frame members having this closed cross section are welded, an extremely rigid frame can be formed. On the other hand, by welding the joint between the frame and another member using a method capable of continuous welding from one side, such as laser welding, the welding strength is improved, and the shape of the joint is not suitable for spot welding. Even if possible, it can be easily welded from one side. Also, if laser welding is adopted, unlike spot welding,
Since continuous welding can be performed, the joint strength of the joint can be improved. Further, when the closed cross section is, for example, a rectangle, this production is relatively easy, and a stable and high-rigidity product can be produced easily and inexpensively by a hydroforming method or the like.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cab under frame structure for a vehicle according to the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a case in which a frame member of the present invention, which will be described later, is employed only in the underframe intermediate portion 1 of the cab underframe 8. Of course, the entire cab under frame 8 may be formed by the frame member of the present invention.

As shown in FIG. 1, a cab underframe 8 of this embodiment is a three-part type in which an underframe front portion 3, an underframe intermediate portion 1 using the frame member of the present invention, and an underframe rear portion 4 are joined. Consisting of The cab underframe 8 is welded to the lower surface of the floor panel 5, the front end of the underframe front portion 3 is connected to the front mount rail 6, and the underframe rear portion 4 is connected to the rear mount rail 7.

As shown in FIG. 2, the underframe intermediate portion 1 in this embodiment is formed by welding two frame members 2 and 2 having the same shape. As shown, the frame member 2
Is made of a hollow body having a rectangular cross section, and is integrally formed in a shape corresponding to the kick-up shape of the intermediate portion 1 of the underframe. The frame member 2 is formed by a hydroforming method or the like, and a relatively large number of frames having a stable shape can be easily manufactured. Further, the two frame members 2 are integrated with one side thereof in contact with each other, and as an integration method, for example, welding means by laser welding is adopted. By laser welding, continuous bead traces 12 are formed above and below the mating portion of the frame members 2.

As shown in FIG. 1, the front end of the underframe intermediate portion 1 is inserted into and fixed to the front portion 3 of the underframe, and the rear end is inserted and fixed to the rear portion 4 of the underframe. 5 and 6 show the front part 3 of the underframe.
3 shows a schematic structure of an underframe rear portion 4. These have a hat-shaped cross section, and a flange portion 13 and a flange portion 14 are formed at the upper end so as to open outward.

Next, a description will be given of a structure for fixing the underframe intermediate portion 1 composed of the frame members 2 and 2 having the above-described structure to the cab floor panel 5, the underframe front portion 3, the underframe rear portion 4, and the like. As shown in FIGS. 3 and 4, all contact surfaces between these members are formed by a method capable of single-side welding by laser welding or the like. In particular, as shown in the drawing, spot contact welding between the floor panel 5 and the underframe intermediate portion 1 and between the underframe front portion 3 and the underframe rear portion 4 and the side surface of the underframe intermediate portion 1 cannot be performed by spot welding. is there. As shown in FIG. 3, a bead 15 is used for welding the front portion 3 of the under frame (or the rear portion 4 of the under frame) and the side surface of the middle portion 1 of the under frame.
The welding is performed by inclining the welding to improve the welding strength. The underframe front part 3 and the underframe rear part 4 are connected to the floor panel 5 by the flanges 13 and
14 comes into contact with the lower surface of the floor panel 5 and is welded. In this example, laser welding is shown as the welding means, but spot welding may be used.

As described above, by employing the underframe intermediate portion 1 having a relatively high rigidity as the cab underframe 8, the deformation of the frame at the time of collision or the like is reduced.
In addition, by making the underframe front part 3 relatively low rigidity, it is possible to make the front part 3 and the peripheral structure relatively absorb impact energy.

In the above-described embodiment, the frame structure of the frame member 2 is used only in the middle portion 1 of the cab under frame 8.
The whole may be formed by the frame member 2 and may have high rigidity. Further, in this example, the frame member 2 having a rectangular cross-sectional shape is used, but the cross-sectional shape is not limited to this. For example, even if the cross-sectional shape changes continuously, the cross-sectional shape may be changed. Good. Further, in this example, the two frame members 2 and 2 are integrated by laser welding or the like, but the invention is not limited to two.

[0018]

1) According to the cab underframe structure for a vehicle according to the first aspect of the present invention, a plurality of high-rigidity frame members having a cross-sectional structure in which at least the kick-up portion at the intermediate portion of the cab underframe is closed. By forming from welding, deformation at the time of collision or the like can be reduced. 2) According to the cab underframe structure for a vehicle according to the second aspect of the present invention, the welded portion is continuously welded by laser welding or the like at the joint between the middle portion of the underframe and the front portion of the underframe. Can be improved in strength. 3) According to the cab under frame structure for a vehicle according to the third aspect of the present invention, by welding the plurality of frame members by laser welding or the like, the frame members are reliably integrated, and the high rigidity frame is formed. Can be formed. 4) According to the cab under frame structure for a vehicle according to claim 4 of the present invention, the frame member is formed by a hydroforming method or the like, and a frame member having a stable shape and quality can be manufactured at a relatively low cost. And it can be manufactured in large quantities.

[Brief description of the drawings]

FIG. 1 is a side view showing a frame structure using a high-rigid under-frame intermediate portion made of a frame member in a kick-up portion of a cab under frame.

FIG. 2 is a perspective view showing a detailed structure of an intermediate portion of an under frame in FIG. 1;

FIG. 3 is a partial side view showing a connection form between an underframe intermediate portion and an underframe front portion in the present invention.

FIG. 4 is a sectional view taken along line AA in FIG. 3;

FIG. 5 is a perspective view showing a schematic structure of a front portion of an under frame connected to a middle portion of the under frame of the present invention.

FIG. 6 is a perspective view showing a schematic structure of a rear portion of an under frame connected to an intermediate portion of the under frame of the present invention.

FIG. 7 is a cab side view showing a cab under frame disposed below the cab.

FIG. 8 is a side view showing a conventional cab under frame reinforcing structure.

FIG. 9 is an enlarged sectional view taken along line BB of FIG. 8;

FIG. 10 is a side view showing a reinforcement structure of a conventional cab under frame.

FIG. 11 is an enlarged sectional view taken along the line CC of FIG. 10;

FIG. 12 is a side view showing an outline of a deformed state of a conventional cab under frame at the time of collision or the like.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Middle part of underframe 2 Frame member 3 Front part of underframe 4 Rear part of underframe 5 Floor panel 6 Front mount rail 7 Rear mount rail 8 Cab underframe 11 Cab 12 Bead trace 15 Bead trace

Claims (4)

[Claims] 1. A cab underframe structure welded to a lower surface of a floor panel, comprising: a substantially horizontal underframe front portion; a rear frame middle portion rising rearward from a rear end; It consists of an underframe rear part that extends almost horizontally from the rear end,
A cab underframe structure for a vehicle, wherein at least the underframe intermediate portion is formed by welding a plurality of frame members forming a closed cross section. 2. A joint portion between the underframe intermediate portion or the like made of the frame member and the underframe front portion and the underframe rear portion, and a joint portion between the underframe intermediate portion and the underframe rear portion and a floor panel are fixed by laser welding or the like. The cab underframe structure for a vehicle according to claim 1, wherein 3. The cab underframe structure for a vehicle according to claim 1, wherein the plurality of frame members are fixed to each other by laser welding or the like. 4. The cab underframe structure for a vehicle according to claim 1, wherein said frame member is formed of a hollow body having a rectangular cross section and is formed by a hydroforming method or the like. .