JPH06144287A - Under carriage frame for motor truck - Google Patents

Abstract

PURPOSE:To dissolve or reduce the end lowered state of a load-carrying platform in the overhang part, behind a wheel base, of a cargo truck so as to improve the commercial value of a merchandise by forming the overhang part, behind a wheel base, of an under carriage frame into upward concave curve shape. CONSTITUTION:The overhang part 20, behind a wheel base (a), of an under carriage frame 10 is formed into upward concave curve shape. This results in dissolving or reducing the end lowered state of a load-carrying platform in the overhang part, behind the wheel base, of a cargo truck or the like so as to improve the commercial value of a merchandise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a truck undercarriage frame suitable for use in a truck, particularly a cargo truck having a undercarriage frame extending rearwardly of rear wheels.

[0002]

2. Description of the Related Art A chassis frame that extends long behind a rear wheel,
In other words, in a cargo truck or the like having a chassis frame with a large length of the overhang portion behind the wheel base, when the cargo frame is loaded on the cargo bed because the chassis frame is conventionally formed substantially linearly. The overhang portion elastically deforms and hangs down, so that the loading platform is in a so-called trailing state.

Of course, the undercarriage frame is designed to have sufficient strength for a preset product load amount, and the drooping itself of the rear end portion of the undercarriage frame itself has no problem in strength. However, there is a problem in that the users of the vehicle and other persons concerned feel a sense of anxiety among the people, and the productability is impaired.

[0004]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above circumstances, and the rear end portion of a chassis frame of a cargo truck or the like prevents or reduces the trailing edge of the cargo bed during loading. Both are intended to reduce the amount of droop and to reduce the anxiety of vehicle users, etc., and to improve the marketability.

[0005]

In order to achieve the above object, the present invention provides a chassis frame of a truck, characterized in that an overhang portion at the rear of the wheel base of the chassis frame is formed by curving upwardly. It is a proposal.

[0006]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. First, in FIG. 1 showing a schematic side view of a cargo truck, reference numeral 10 is a chassis frame, 12 is a cab mounted on a front end portion of the chassis frame 10, and 14 is a cab.
Is a front wheel, and 16 and 18 are rear wheels of two rear axles.

The undercarriage frame 10 has an overhang portion 20 extending rearward of the wheel base a over a length αa, and the overhang portion 20 has a concave upward curved shape, and its radius of curvature is R = βa. is there. Since the overhang portion 20 has a concave upward curved shape, the rear wheels of the chassis frame 10 are positioned d above the extension line of the wheel base portion when no load is applied, as illustrated.

An example of a concrete structure of the overhang portion 20 in the chassis frame 10 is shown in FIGS. 3 and 4. In the figure, reference numeral 22 is a pair of left and right side rails extending in the vehicle front-rear direction and each having a groove-shaped cross section, and 24 is a plurality of cross members arranged so as to extend in the vehicle width direction.

The cross member 24 is composed of an upper member 26 having a hat-shaped cross section, and a lower member 30 fixed to both end portions of the upper member 26 in the vehicle width direction by rivets or bolts 28. The upper member 26
A V-shaped widening portion is formed by the vehicle width direction end portion of the vehicle and the lower member 30, and mounting flanges 26f and 30f formed by bending the widening portion in the vertical direction are formed on the web 22w of the side rail 22. It is secured by a number of rivets or bolts 32.

As described above, by constructing the structure in which both ends of the cross member 24 in the vehicle width direction are fixed to the webs 22w of the side rails 22, the overhang portion 20 is formed.
Even if the side rail 22 has a circular arc shape with a radius of curvature R = βa and is curved upward in a concave shape, the cross member 24 can be securely fastened to the side rail 22.

Next, the upward displacement amount d of the overhang portion 20 is expressed by the following mathematical formula 1.

[0012]

[Equation 1]

In FIG. 2, the vertical axis represents the amount of upward displacement d of the above equation (1).
FIG. 4 is a diagram in which the horizontal axis represents the multiplier β of the radius of curvature R = βa. As an example, the wheel base a = 6
300 (mm), length of the overhanging portion 20 αa =
0.67 × 6300≈4200 (mm) in a rear two-axis large cargo truck, when the cargo of the rated weight is loaded on the loading platform mounted on the chassis frame 10, the trailing end amount δ of the rear end of the chassis frame δ _{When o} = 50 (mm), the above-mentioned upward displacement amount d is larger than twice the trailing descent amount δ _o , that is, d>
In order to obtain 2δ _o , β <14, and the upper displacement amount d and the trailing descent amount δ _o are set to be equal to each other, so that the chassis frame 10
When is set to be a linear state, β = 28.
Further, with respect to the above-mentioned trailing descent amount δ _o , the amount of droop from the linear state of the rear end of the chassis frame 10 that is practically allowable is 35
Assuming (mm), β is about 100. Therefore,
In the case of a large cargo truck, the above-mentioned overhang portion 20
In practice, the radius of curvature R is appropriately selected within a range of β = 10 to 100, that is, R = (10 to 100) a.

In the rear overhang portion 20 of the chassis frame 10, since the side rails 22 are curved upward in a concave shape, both end portions of the cross member 24 in the vehicle width direction are vertically flanged as usual. If a structure for fastening to is adopted, a gap is likely to be formed between the upper and lower flanges of the side rail 22 and the corresponding end of the cross member 22, and if it is forcibly tightened so that there is no gap, bolts, rivets, etc. There is a problem that the stress remaining in the fastening member or the plate material around the fastening member becomes large and cracks or the like are likely to occur, but as described above, the cross member 2
By fastening 4 to the webs 22w of the siderails 22, the difficulties mentioned above due to the bending of the siderails 22 can be easily overcome.

Further, in the above embodiment, the cross member 24
Although a so-called alligator-type cross member is exemplified as the above, it is clear that a groove-shaped or I-shaped cross-member can be adopted as the cross-sectional shape, and a gusset is interposed at the joint between the cross-member and the side rail. It is also clear that this can be done. In addition, the method of fastening the cross member and the side rail in the portion other than the rear overhang portion 20 of the chassis frame 10 is arbitrary, but like the overhang portion 20, the web of the side rail is aligned with the cross member in the vehicle width direction. Fastening the ends is preferable from the viewpoint of improving the durability and reliability of the entire chassis frame.

[0016]

As described above, the undercarriage frame of the truck according to the present invention is characterized in that the overhang portion at the rear of the wheelbase of the undercarriage frame is formed by curving upward in a concave shape. By eliminating or reducing the trailing edge of the rear end of the loading platform, there is an advantage that the vehicle user's anxiety can be dispelled and the marketability can be improved.

[Brief description of drawings]

FIG. 1 is a schematic side view of an entire truck showing an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a radius of curvature of a rear overhang portion and an upward displacement amount of a rear end of a chassis frame of the truck shown in FIG.

FIG. 3 is a plan view showing, on an enlarged scale, a part of a rear overhang portion in a chassis frame of the truck shown in FIG.

4 is a front view of the chassis frame shown in FIG. 3. FIG.

[Explanation of symbols]

 10 chassis frame 12 cab 14 front wheels 16 and 18 rear wheels 20 overhang

Claims (1)

[Claims] 1. An undercarriage frame for a truck, wherein an overhang portion behind a wheelbase of the undercarriage frame is formed by curving upward in a concave shape.