JPH0790798B2 - Chassis frame with packing box - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a chassis frame of a vehicle including a luggage box such as a truck.

(Prior Art) An ordinary truck includes a pair of left and right side rails extending in the front-rear direction of the vehicle body and having groove-shaped cross-sections, and a plurality of side rails arranged in the vehicle width direction and having both ends fixed to the side rails. An undercarriage frame composed of individual cross members is provided, and a luggage box is mounted on the undercarriage frame via an intermediate member such as a vertical joist or a subframe, and is attached to the side rail by a fixing means such as a U bolt. It is tightened.

A member having a groove-shaped or I-shaped cross section is widely used for the cross member. In either case, the upper flange and the lower flange of the cross member are substantially related to the plate thickness and the width in the vehicle front-rear direction. It is customary to have substantially equal shapes.

(Problems to be solved by the invention) When a vehicle such as a truck is used under severe conditions such as traveling at a high speed on a rough road having severe unevenness, a large torsion load acts on the chassis frame, A large stress may be generated in the cross member, especially near the joint with the side rail.

A chassis in which a pair of left and right side rails 10 each having a groove-shaped cross section as shown in the conceptual side view of FIG. 11 are fastened to both ends of a cross member 12 having a groove-shaped cross section by rivets or bolts. When a torsion test was performed on the frame 14, when the chassis frame 14 alone was used, the cross member
The upper and lower flanges 12u and 12l of the twelve are subjected to vehicle front-rear shearing forces having substantially equal magnitudes as indicated by arrows Su and Sl in the figure, respectively, which are shown in the conceptual side view of FIG. As described above, when the luggage box 18 is mounted on the undercarriage frame 14 via the vertical joist or the subframe 16 and is tightly fixed to the side rail 10 by the fixing means 20 such as a U bolt, the arrow Su in the drawing indicates It has been found that a shear force in the vehicle body front-rear direction, which is much larger than that of the upper flange 12u, acts on the lower flange 12l, as indicated by'and Sl '. This test result shows that in an ordinary truck undercarriage frame in which the packing box 18 is mounted on the undercarriage frame 14, the plate thicknesses of the upper flange 12u and the lower flange 12l of the cross member 12 and the width in the vehicle front-rear direction are substantially equal. Conventional cross member 12
Lacks rationality in material distribution, if the lower flange
Given that 12l has the necessary and sufficient strength, it is an indication that the upper flange 12u was of excessive quality in strength, leading to a corresponding increase in weight.

In view of the above circumstances, the present invention determines the plate thicknesses of the upper and lower flanges and the width in the vehicle front-rear direction so as to adapt to the difference in shear force in the vehicle front-rear direction acting on the upper flange and the lower flange of the cross member. The purpose of the present invention is to reduce the weight of the cross member and thus the weight of the chassis frame.

(Means for Solving the Problems) A chassis frame with a luggage box according to the present invention was created to achieve the above-mentioned object, and has a pair of left and right extending in the vehicle front-rear direction with a groove-shaped cross section. An undercarriage frame including a siderail and a cross member having a groove shape or an I-shaped cross section and arranged in the vehicle width direction and having both ends thereof fastened to the siderail by rivets or bolts, and the undercarriage frame. In a case comprising a luggage box mounted on the side rail and fastened to the side rail by a fixing means such as a U-bolt, the upper flange and the lower flange near the end of the cross member adjacent to the side rail are upward. Let the flange thickness and the vehicle front-rear direction width be t _u and b _u , the lower flange plate thickness and the vehicle front-rear direction width be t _l and b _l , and Z _u = t _u b ² _u / 6, Z _l = and t _l b ² _l / 6 When, 1.2 ≦ Z _l
It is characterized in that it is formed in a shape that satisfies / Z _u ≤5.

(Operation) According to the present invention, the upper flange and the lower flange of the cross member are formed in a shape that satisfies the above expression, and the upper flange is formed to be lighter than the lower flange. Therefore, it is possible to remove the excess weight of the upper flange while ensuring the plate thickness and the width in the vehicle front-rear direction that are necessary and sufficient for the lower flange in terms of strength.

(Embodiment) An embodiment of the present invention will be specifically described below with reference to FIGS. 1 to 10. First, in the first embodiment of the present invention shown in FIGS. 1 to 3, the chassis frame 14 includes a pair of left and right side rails extending in the vehicle front-rear direction and having a groove-shaped cross section.
10 and a large number of rivets 22 on the same rail 10w
Alternatively, groove-shaped gussets 24 fixed by bolts of substantially the same effect, and upper flanges 24u and lower flanges 24l of the same gussets are respectively provided with corresponding end portions in the vehicle width direction of upper flanges 12u and lower flanges 12l. Multiple rivets 26
Alternatively, it is composed of a groove-shaped cross-section member 12 fastened by bolts of substantially the same effect.

The cross member, as clearly shown in the perspective view of FIG.
The thickness of the 12 upper flanges 12u is t _u , and the width in the vehicle front-rear direction is b _u.
Also, assuming that the plate thickness of the lower flange 12l is t _l and the width in the vehicle front-rear direction is b _l , the section coefficients of the upper flange and the lower flange in the vehicle front-rear direction are Z _u = t _u b ² _u / 6, Z _{l, respectively.} = t when the ^{_{l b 2 l / 6, 1.2}} ≦ Z l / Z u ≦ 5 the upper and lower flanges so as to satisfy 12u and 12l are formed. As already described with respect to the chassis frame with the packing box in FIG. 12, the lower flange of the cross member 12 when the chassis frame 14 is twisted.
The vehicle front-rear shear force S _l ′ acting on 12l is larger than the vehicle front-rear shear force S _u ′ acting on the upper flange 12u, but the respective magnitudes are the torsional rigidity of the chassis frame 14 itself and the packing box. 18 torsional rigidity, chassis frame 14 and packing box
18 Since there are various differences depending on the constraint conditions between each other, the above Z _l / Z _u
The value of is appropriately determined within the above range according to the characteristics of each vehicle. The ^{_{Z l = t l b 2 l}} / 6 of the lower flange 12l the shearing force S _l 'and necessary and sufficient to adapt to, whereas S _l'
Z _{u of the} upper flange 12u on which a smaller shear force S _u ′ acts
= T _u b ² _u / 6 has a value commensurate with the small shearing force S _u ′, so that the cross member 12, in comparison with the conventional structure in which the strengths of the upper flange and the lower flange are substantially equal to each other,
As a result, there is an advantage that the weight of the chassis frame 14 can be reduced. The rationale for the value of Z _l / Z _u above 1.2 is 1.2.
If less than, the effect of weight reduction is small compared to the conventional cross member in which the plate thickness of the upper and lower flanges and the width in the vehicle front-rear direction are substantially equal, while the value of Z _l / Z _u is set to 5 or less Chassis frame 14 with various torsional rigidity in the practical range
It is based on the result of the investigation of the combination of the cargo bed 18 and the cargo bed 18. Becomes the Z _l / Z _u> 5, when vertical bending load is applied to the cross member, the upper and lower only bending buckling strength difference between the two flanges is increased, and to obtain the strength necessary to upper flange of the cross member Then, since the lower flange becomes large, there arises a problem that the weight increases, and the practicality becomes poor.

In the illustrated embodiment, the upper flanges 12u and 12l have the same plate thickness t _u and the entire length in the vehicle width direction of the cross member 12.
Although it is formed with t _l and widths b _u and b _l, the flange width near the vehicle front-rear direction center plane O-O of the chassis frame 14 is smaller than the flange widths b _u and b _l adjacent to the side rails 10. As a result, the weight can be further reduced.
That is, as shown in FIG. 2, the equivalent center of gravity g of the rivet 26 or the bolt group of the same effect that fastens both ends of the lower flange 12l of the cross member 12 to the corresponding lower flange 24l of the gusset 24 (details will be described later). , And the distance in the vehicle width direction between the left and right equivalent centers of gravity g is lg, the plate thickness and width of the lower flange 12l in the range of 0.2lg to 0.45lg from the center plane O-O are required. and the ^{_{Z l = t l b l 2}} /6 with strength,
The remaining central portion may have a smaller flange width. This also applies to the upper flange 12u.

Explaining the meaning of the equivalent center of gravity,
In FIG. 10, the transverse elastic moduli of arbitrary numbers (two or more) of rivets or bolts R ₁ , R ₂ ... R _i ... R _n-1 , R _n are respectively G ₁ , G ₂ ... G _i
… G _n-1 , G _n , the cross-sectional area of each rivet or bolt is a ₁ , a _{2 respectively}
… A _i … a _n-1 , a _n , and coordinate vector of each rivet or bolt
_{When 1} , _2, ... _i ... _n-1 , _n , the coordinate vector _g of the equivalent center of gravity _g is It is represented by.

Next, a second embodiment of the present invention shown in FIGS. 4 and 5 will be described. In this embodiment, an upper flange 12u having a plate thickness t _u of the cross member 12 and a width b _{u in the} vehicle body front-rear direction, which is similar to that of the first embodiment, corresponds to the upper flange 1 of the side rail 10.
The lower flange 12l, which is fastened to the 0u by a plurality of rivets 26 or bolts having substantially the same effect, and which has a plate thickness t _l and a width b _{l in the} vehicle front-rear direction, is a corresponding lower flange 1 of the side rail 10.
It is fastened to the 0l by a plurality of rivets 26 or bolts of substantially the same effect.

Like the first embodiment, the ratio of the ^{_{Z u = t u b u 2}} /6 and ^{_{Z l = t l b l 2}} /6 in the upper flange 12u and lower flange 12l, 1.2
≦ Z _l / Z _u ≦ 5 is selected, and the shear force S _u ′ in the vehicle longitudinal direction acting on the upper flange and the lower flange is
By adapting to S _l ′, it is possible to reduce the weight of the cross member 12 while ensuring the strength thereof, and thus to reduce the weight of the chassis frame 14. In FIG. 6, both ends of the upper flange 12 and the lower flange 12l of the cross member 12 having a groove-shaped cross section are extended in the vehicle width direction and bent in the vertical direction, and the bent flange portions 12u 'and 12l' are provided with a plurality of rivets. 26 or a modified example of the second embodiment fastened to the web 10w of the side rail 10 by a bolt having the same effect, and in this case also, the ratio of Z _u and Z _{l in} the upper and lower flanges 12u and 12l is 1.2. By appropriately selecting within the range of 5 or less, the same weight reduction effect can be achieved.

Further, FIGS. 7 and 8 show a third embodiment of the present invention, in which the webs of two groove-shaped members are abutted back-to-back and integrally joined by a large number of rivets 28. A cross member 12 having an I-shaped cross section is formed, and both ends of the upper flange 12u and the lower flange 12l of the cross member are attached to the corresponding upper flange 10u and lower flange 10l of the side rail 10 by a plurality of rivets 26, respectively. It has been concluded.

Let the upper flange 12u of the cross member 12 have a plate thickness t _u , the vehicle front-rear direction width be b _u , the lower flange 12l plate thickness t _{l be} the vehicle front-rear direction width b _l, and Z _u = t _u b ² _u Ratio of / 6 and Z _l = t _l b ² _l / 6 Z _l / Z
_By appropriately selecting _u in the range of 1.2 or more and 5 or less according to the torsional rigidity of the luggage box 18 and chassis frame 14, etc.,
The weight of the cross member 12 can be reduced while ensuring the necessary and sufficient strength. Further, instead of the cross member 12 shown in FIG. 8, as shown in FIG.
It is possible to use a cross member 12 having an I-shaped cross section formed by fixing the plate material forming the upper flange 12u, the plate material forming the lower flange 12l, and the plate material forming the web 12w by welding. Can have substantially the same effect.

Furthermore, when fixing both ends of the cross member 12 shown in FIGS. 8 and 9 to the side rails 10, the same gusset as in the first embodiment can be used, and the upper flange of the cross member 12 can be used. 12u and the lower flange 12l are extended in the width direction of the vehicle and bent in the same manner as in Fig. 6, and the side rail
It is fixed to the web 10w of 10 by rivets, or the web 12w of the cross member 12 is similarly extended in the vehicle width direction and bent in the vehicle front-rear direction to form a mounting flange, and the mounting flange is attached to the side rail web 10w. It can be fixed with rivets. Then, in all of these modified examples, it is possible to achieve a weight reduction effect that is substantially the same as that of the third embodiment.

Still further, in the above-mentioned second and third embodiments, and their modifications, the side rails 10 of the cross member 12 are provided.
Upper flange 12u and lower flange 12l adjacent to
It is substantially the same as in the first embodiment that the weight of the cross member 12 can be further reduced by reducing the flange width in the vicinity of the center plane O-O with respect to the flange width.

(Effects of the Invention) As described above, the chassis frame with load according to the present invention has a pair of left and right side rails having a groove-shaped cross section and extending in the vehicle front-rear direction, and a groove shape or an I-shape cross section. None An undercarriage frame which is arranged in the width direction of the vehicle and has a cross member whose both ends are fastened to the side rails with rivets or bolts; In a case where the side rail is provided with a packing box tightened, the upper flange and the lower flange near the end of the cross member adjacent to the side rail have a plate thickness of the upper flange and a width in the vehicle front-rear direction of t _u. and b _u, the thickness and the longitudinal direction of the vehicle width of the lower flange and t _l and b _l, and ^{_{Z u = t u b u 2}} /6, Z l = t l b l 2/6
Is characterized by being formed in a shape that satisfies 1.2 ≦ Z _l / Z _n ≦ 5, and by making the shape of the cross member in the chassis frame with a luggage box an appropriate shape according to the acting force, The weight of the chassis frame can be reduced, which is industrially beneficial.

[Brief description of drawings]

FIG. 1 is a plan view showing the first embodiment of the present invention (center plane O-
Left side of O) and bottom view (right side of center plane OO), FIG. 2 is a perspective view showing the cross member 12 in FIG. 1 extracted, and FIG. 3 is a line III-III of FIG. FIG. 4 is a partial sectional view taken along the arrow direction, FIG. 4 is a plan view (left side of the center plane OO) and a bottom view (right side of the center plane OO) showing the second embodiment of the present invention, and FIG. FIG. 6 is a partial sectional view taken along the line VV of FIG. 4 as seen in the direction of the arrow, FIG. 6 is a partial sectional view similar to FIG. 5 showing a modification of the second embodiment, and FIG. A plan view (left side of the center plane OO) and a bottom view (right side of the center plane OO) showing a third embodiment of the invention, FIG. 8 is a sectional view taken along line VIII-VIII of FIG. FIG. 9 is a sectional view similar to FIG. 8 showing a modified example of the cross member 12 in FIG. 7, FIG. 10 is a diagram explaining the equivalent center g of the rivet or bolt group, and FIG. If FIG. 12 is a conceptual side view showing a mode of shearing force acting on the upper flange and the lower flange of the cross member, and FIG. 12 is a conceptual side view similar to FIG. 11 when the chassis frame with a luggage box is twisted. 10 …… Side rails, 12 …… Cross members, 14 …… Car frame, 18 …… Packing boxes, 20 …… Fixing means such as U bolts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akinori Oikawa 5-3-8 Shiba, Minato-ku, Tokyo Within Mitsubishi Motors Corporation (72) Kunio Hara 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Automotive Industry Co., Ltd.

Claims (1)

[Claims] 1. A pair of left and right side rails having a groove-shaped cross section and extending in the vehicle front-rear direction, and a groove-shaped or I-shaped cross section.
An undercarriage frame having a mold and having cross members which are arranged in the vehicle width direction and whose both ends are fastened to the side rails with rivets or bolts, and a fixing means such as a U bolt mounted on the undercarriage frame. The upper flange and the lower flange in the vicinity of the end of the cross member adjacent to the side rail have a thickness of the upper flange and a width in the vehicle front-rear direction. t _u and b _u , the thickness of the lower flange and the width in the vehicle front-rear direction are t _l and b _l , and Z _u = t _u b ²
Undercarriage frame with packing box, characterized in that it has a shape satisfying 1.2 ≦ Z _l / Z _u ≦ 5 when _u / 6, Z _l = t _lb ² _l / 6