JP3039207B2 - Underframe for vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chassis frame for vehicles such as trucks.

[0002]

[Definition] In this specification, the term "equivalent center of gravity" is defined as follows with respect to a plurality of rivets for fixing both ends of the cross member in the vehicle width direction to the side rails. That is, in FIG. 19, the rivet _R 1 of 2 or more arbitrary _{number, R} 2 ... _R 1 ... each _G 1 a modulus of transverse elasticity of _{R n,} G
₂ ... G ₁ ... G _n and the cross-sectional area of each rivet are a ₁ ,
_{a 2 ... a 1 ... a n} , further each _X 1 and X and Y coordinates of each _{rivet, X} 2 ... _X 1 ... _{X n} and _{Y 1, Y} 2 ... _{Y 1}
... when a Y _n, X-coordinate Xg and Y coordinates Yg equivalent center of gravity G is represented by the respective following equations (1) and (2).

[0003]

(Equation 1)

[0004]

(Equation 2)

[0005]

2. Description of the Related Art An ordinary truck is composed of a pair of left and right side rails extending in the front-rear direction of a vehicle body, each having a groove shape in cross section, and a plurality of rivets attached to the side rails at both ends arranged in a vehicle width direction. The cross member includes a plurality of fixed cross members. The cross members include a member having a groove-shaped cross section, a member having an I-shaped cross section, and V-shaped portions extending at both ends connected to the side rails. An alligator-type cross member having an open connection portion or the like is appropriately employed.

When a vehicle such as a truck travels on extremely rough roads or irregular terrain, a large torsional load acts on the chassis frame, and a large stress is generated on the cross member, particularly near the joint with the side rail. And problems such as cracks are likely to occur. Conventionally, in order to prevent breakage of the cross member at the joint with the side rail, a method of interposing and reinforcing a necessary number of reinforcing members such as stiffeners at the joint has conventionally been adopted. However, this method has a drawback that the weight and manufacturing cost of the chassis frame cannot be avoided.

Accordingly, the present applicant has previously proposed Japanese Patent Application No. 314392 in 1988, "Vehicle Undercarriage Frame" (hereinafter referred to as an already proposed invention). According to the invention, the cross member is fastened to a side rail extending in the vehicle front-rear direction with a plurality of rivets at both ends of a cross member extending in the vehicle width direction. the longitudinal direction of the vehicle body width at the position P _B of the equivalent center of gravity near the longitudinal center plane of the plurality of rivets and the distance X _B have distance to Kurumahaba direction from the Y _B, a distance X _a from longitudinal center plane of the vehicle = _X B / 2 to the longitudinal direction of the vehicle body width at the position _{P a} had distance and _{Y a,} when further the distance to the equivalent center of gravity and _{L G} from the center ^{_{plane, (Y B / Y a)}} 2 = 1 .5-
A 2.5, and is characterized in that the shape of the outer portion free edge between said P _A and P _B are comprises a planar shape forming a concave-curved the L _G of curvature greater than the above It has been confirmed that there is an advantage that the weight and manufacturing cost of the chassis frame can be effectively reduced as compared with the chassis frame reinforced based on the conventional method.

[0008] the cross member of the chassis frame in the invention of the previously proposed, outer portions that constitute the vehicle width direction end portion or the P _A and concave curve shape that is flared toward the Kurumahaba outwardly between the P _B inner portion free edge of the central portion except for the portion of the free end edge, but comprises a straight flat shape of the constant width Y _a, then further research overlapped results, added to the planar shape of the cross member It has been found that the weight of the cross member can be further reduced without deteriorating the durability and reliability of the chassis frame, and the manufacturing cost can be reduced accordingly.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and by making additional improvements to the underframe according to the above-mentioned proposed invention, the weight and manufacturing cost of the underframe are further increased. It is intended to achieve a reduction in the amount.

[0010]

In order to achieve the above object, according to the present invention, both ends of a cross member extending in a vehicle width direction are fastened to side rails extending in a vehicle longitudinal direction by a plurality of rivets. in what is formed by, the cross member, the longitudinal direction of the vehicle body width at the position P _B of the equivalent center of gravity near the longitudinal center plane of the plurality of rivets and the distance X _B have distance to Kurumahaba direction from the vehicle Y _B and then, the longitudinal direction of the vehicle body width at the position P _a and the distance X _{a =} X B / ₂ from the longitudinal center plane Kurumahaba direction have distance of the vehicle and Y _a,
Also, when the distance from the vehicle longitudinal center plane to the equivalent center of gravity was ^{_{L G, (Y B / Y}} A) 2 = 1.5~2.
5 is a, and the P _A and the outer shape of the free end edge includes a concave-curved plane shape of the L _G greater curvature, further inside the inner from the outer free edge between P _B The flat shape of the free edge is smoothly connected to the outer free edge, and the width Y _{O at the} center plane in the vehicle longitudinal direction is equal to the width Y.
_A vehicle chassis frame characterized by being formed by a curve smaller than _A is proposed.

[0011]

According to the present invention, the plane shape of the outer free edge near the both ends in the vehicle width direction of the cross member in the chassis frame is changed to a radius of curvature expanding outward in the vehicle width direction in the same manner as in the above-mentioned proposed invention. In the proposed invention, the plane shape of the free edge of the central portion of the cross member, which has been linear, is smoothly connected to the outer free edge of the concave curve. In addition, since the width at the center plane in the front-rear direction of the vehicle is formed by a curve smaller than the width of the connection portion with the outer free edge, it is possible to further reduce the weight without impairing the durability and reliability of the chassis frame. Become.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. First, in the first embodiment of the present invention shown in FIGS. 1 and 2, reference numeral 10 in the drawings generally indicates a chassis frame of a vehicle such as a truck, and the chassis frame extends in the vehicle longitudinal direction. A side rail 12 having a pair of left and right cross-sectional shapes forming a groove shape, and a cross arranged in the vehicle width direction and having both end portions fastened to the web 12w of the side rail by a number of rivets 14 to form a groove shape. It has a member 16.

The cross member 16 has a mounting flange 16f 'which is formed by extending the upper and lower flanges 16f outward in the vehicle width direction and bending the mounting member 16b in the vertical direction. 14 is fixed to the web 12w of the side rail. The number of rivets 14, since it is arranged on the side rail web 12w, and the equivalent center of gravity G, the distance L _G between the longitudinal center plane Y-O of the vehicle, substantially cross member 16 It is equal to one half of the total length in the vehicle width direction, that is, the X direction.

Upper and lower flanges 16 of the cross member 16
The planar shape of the free edge of f, as shown, the inner free edge to Kurumahaba medial position P _A on both sides from the longitudinal center plane Y-O is, arcs, ellipses, parabolas other relatively molded by the inner curved portion 16fa curvature radius consists of a large curve, the outer free end edge from said position P _a to the position P _B near the Kurumahaba outward ends, concave curve which is expanded toward the Kurumahaba outwardly , And the outer curved portion 16fb is formed by the center plane YO.
At a distance L _G having a larger radius of curvature, and the position P _A between the equivalent center of gravity G, it is smoothly connected to the inner curved portion 16fa and the outer curved portion 16Fb.

[0015] The position P _B is set in the vicinity of the equivalent center of gravity G (including of course the center of gravity position G) with respect Kurumahaba direction,
The longitudinal direction of the vehicle body width at the position _{P B} is _{Y B,} also the distance _{X B} from the center plane Y-O distance _{X A} position _{P B} from before and after the position _{P A} direction center plane Y-O 1/2, is set to bisection point of the straight line OP _B in FIG. 1 in other words. Also, the width of the longitudinal direction of the vehicle body at the position P _A is Y
_A, the width in the center plane Y-O a _{Y O,} a _Y A> _{Y O} as shown.

[0016] Then, the front-rear direction of the width _{Y A} and _{Y B} at both end positions _{P A} and _{P B} of the outer curved portion 16Fb,
Respectively ^{_{(Y B / Y A) 2}} = and 2.0 the relationship is formed to stand, also the width _{Y O} in the longitudinal direction at the center or center plane Y-O of the inner curved portion 16Fa, the undercarriage frame 10 The dimension is determined to be large enough to withstand the longitudinal shear force generated in the cross member 12 based on the set torsional load set in consideration of the maximum torsional load acting during actual running.

The planar shape of the free edge, an outer curved portion 16fb which flares outwardly facing forming a shallow concave curve shape of L _G of curvature greater than the Kurumahaba opposite end portions as described above, the inner central portion The torsion test was performed on the underframe 10 having the cross member 16 including the curved portion 16fa, and the stress generated at the free edges of the upper and lower flanges 16f was measured. In the vicinity, the generated stress is sufficiently small, and since the outer curved portion 16fb and the inner curved portion 16fa are smoothly connected to each other, there is no problem that stress concentration occurs at the connecting portion, and the shear force mainly in the front-rear direction is reduced. regard the inner curved portion 16fa of the cross member central portion in question, sufficiently smaller set than width Y _a of width Y _O position X _a on the longitudinal center plane Y-O It was confirmed that there was no problem in strength even if it was set. As a result, the safety of the vehicle against rough roads and rough terrain is high, the durability and the reliability are excellent, and the width of the cross member 16 at the center in the width direction of the vehicle at the free end is constant. compared to the present invention already proposed that the linear values Y _a, by width Y _O on longitudinal center plane Y-O is the above Y _a smaller inner curved portion 16Fa, the width Y _a and Y _O The weight of the cross member 16 can be reduced by about several percent by an amount corresponding to the difference, and the advantage that the manufacturing cost can be reduced correspondingly is obtained.

Further, an outer curved portion 1 comprising a concave curve which is expanded outwardly of the upper and lower flanges 16f of the cross member 16 is provided.
Results The width _{Y B} of the outer tested while varying relative inward width _{Y A} of 6Fb, the ^{_{(Y B / Y A) 2}} = 2 is optimal, this value is 2.5 or more When the stress reduction effect reaches a peak, there is a problem that the weight is increased. On the other hand, when the above value is 1.5 or less, the stress reduction effect is not sufficient, and there is a problem that anxiety about durability and reliability increases. is there.

FIG. 3 shows that the web 16w of the cross member 16 extends outward in the vehicle width direction and is bent in the front-rear direction to form a mounting flange 16w '.
This shows a second embodiment of the present invention in which w 'is fastened to the web 12w of the side rail 12 by a number of rivets 14, and the outer and inner free edges of the cross member 16 have substantially the same planar shape as that of FIG. Is the same as Further, the width Y of the outer curved portion 16fb formed of a concave curve which is expanded outward at both end portions in the vehicle width direction of the upper and lower flanges 16f of the cross member.
_A and _{Y B,} as the first embodiment ^{_{(Y B / Y A) 2}} =
It is set in the range of 1.5 to 2.5. Also in the second embodiment, the maximum stress of the upper and lower flanges 16f of the cross member can be reduced in the same manner as in the first embodiment, and the plane shape of the inner free edge at the center of the cross member is defined by the inner curved portion 16fa. By doing so, it was confirmed that weight and manufacturing cost could be reduced.

Next, FIGS. 4 and 5 show a third embodiment of the present invention. In this embodiment, both ends of the upper and lower flanges 16f of the upper and lower flanges 16f of the cross member 16 having a groove-shaped cross section are fastened to the corresponding upper and lower flanges 12f of the side rail 12 by a number of rivets 14.

Upper and lower flanges 16 of the cross member 16
As in the first embodiment, the outer and inner free edges of f are smoothly connected to the outer curved portion 16fb, which is a concave curve that expands outward at both ends in the vehicle width direction, and the outer curved portion 16fb. It is formed by an inner curved portion 16fa composed of a curve such as an arc, an ellipse, a parabola, and a hyperbola.

The outer curved portion 16f of the cross member 16
b, the position P _B of the equivalent center of gravity G is substantially equidistant X _B of the number of rivet 14 from the longitudinal center plane Y-O of the vehicle
The width Y of the upper and lower flanges 16f in the longitudinal direction of the vehicle body
And _B, between the longitudinal direction of the vehicle body width _{Y A} at the distance _X A _{= X} B / 2 becomes bisecting position _{P A} from the center plane Y-O,
(Y _B / Y _A ) ² = 1.5 to 2.5, preferably 2, so that the relationship of 2 is satisfied, and the distance LG between the center plane YO and the equivalent center of gravity _G = has a _{X B} larger radius of curvature. In the above inner curved portion 16Fa, width Y _O on longitudinal center plane Y-O of the vehicle is set to be smaller than the width Y _A vehicle body longitudinal direction of the both end portions.

FIGS. 6 and 7 show a fourth embodiment of the present invention. In this embodiment, the upper and lower flanges 16f of the cross member 16 having a groove-shaped cross section are fixed to the corresponding upper and lower flanges 18f of the gusset 18 having the groove-shaped cross section by a plurality of rivets 14,
The gusset 18 has its web 18w fixed to a web 12w of an adjacent side rail by a plurality of rivets 20.

The upper and lower flanges 16 of the cross member 16
The outer and inner free edges of f are smoothly connected to the outer line portion 16fb, which is a concave curve that expands outward at both ends in the vehicle width direction, and the outer curve portion 16fb, as in the first embodiment. And an inner curved portion 16fa formed of a curved line such as an arc, an ellipse, a parabola, or a hyperbola.

Outer curved portion 16fb of the cross member
Has a width Y _B vehicle longitudinal direction of the upper and lower flanges 16f from longitudinal center plane Y-O at the position P _B of the equivalent center of gravity G is substantially equidistant X _B of the plurality of rivets 14 of the vehicle,
Between the distance _X A _{= X} B / vehicle longitudinal direction in the two becomes bisecting position _{P A} width _{Y A} from the center plane _Y-O, (Y _B
/ Y _A ) ² = 1.5 to 2.5, preferably 2, so that the relationship of 2 is satisfied, and the distance L _G = X _B between the center plane YO and the equivalent center of gravity G It has a large radius of curvature. In the inner curved portion 16fa,
To width Y _A vehicle body longitudinal direction of the both end portions is set so as width Y _O on longitudinal center plane Y-O of the vehicle is reduced.

Regarding the third embodiment and the fourth embodiment,
When the maximum stress generated in the upper and lower flanges 16f of the cross member 16 was examined by performing a torsional test, the stress generated in each part could be sufficiently reduced as in the first embodiment. It has been confirmed that weight and manufacturing cost can be reduced by setting the planar shape of the free edge to the inside curved portion 16fa.

FIGS. 8 and 9 show a fifth embodiment of the present invention. In this embodiment, an I-shaped cross section composed of upper and lower flanges 16f and a vertical web 16w connecting the central portions of the upper and lower flanges is shown. A cross member 16 is used. The cross member 16 has a mounting flange 16f 'similar to that shown in FIG. 2 formed by extending the upper and lower flanges 16f outward in the vehicle width direction and bending the same in the vertical direction to the web 12w of the side rail 12 by a plurality of rivets 14. It is fixed.

Upper and lower flanges 16 of the cross member 16
f is an outer curved portion 16f formed of a concave curve that expands outward at both ends in the vehicle width direction at both ends in the vehicle width direction.
b and an arc smoothly connected to the outer curved portion 16fb,
Inner curved part 16 composed of curves such as ellipse, parabola and hyperbola
fa.

Outer curved portion 16fb of the cross member
Is located slightly closer to the center plane YO than the plurality of equivalent centers of gravity G from the center plane YO in the front-rear direction of the vehicle.
Flange distance from -O is at the position _{P B} of _{X B} 16
The longitudinal direction of the vehicle body width of f and _{Y B,} when the longitudinal direction of the vehicle body width of the flange 16f at the distance _X A _{= X} B / 2 only distance only position _{P A} from the center plane Y-O was _{Y A,} Y
Between the _B and ^{_{Y A (Y B / Y A}} ) 2 = 1.5~2.5,
Preferably, a relationship L2 is established, and a distance L between the center plane YO and the equivalent center of gravity G is formed.
It is formed to have a radius of curvature larger than _G.
On the other hand, the inner curved portion 16fa is connected to the outer curved portion 16fa.
to width Y _A vehicle body longitudinal direction of the end portions to be connected to fb, width Y _O in the center plane Y-O is set small.

As described above, the planar shape of the free end edge of the upper and lower flanges 16f near the joint with the side rail 12 includes an outer curved portion 16fb formed of a concave curve having a large radius of curvature that is expanded outward, and 16fa inside curved part
Chassis frame 10 having a cross member 16 comprising
And a chassis frame having a normal I-shaped cross member having substantially the same width in the front-rear direction of the upper and lower flanges 16f over the entire length in the vehicle width direction. When the generated stress at the free edges of the upper and lower flanges 16f was examined, the former generated stress was significantly smaller than the latter, so that the durability and reliability were excellent, and the outer curved portion 16f was excellent.
The stress does not concentrate on the connecting portion between the fb and the curved portion 16fa.
Width Y _O both end portions of the width Y _A from sufficiently small curved portion 16 at
It was confirmed that the weight and the manufacturing cost can be reduced by using fa.

FIG. 10 shows a sixth embodiment of the present invention. In this embodiment, a cross member 16 having an I-shaped cross section having the same planar shape as that of the fifth embodiment is provided with upper and lower flanges 16.
f are fastened to the upper and lower flanges 12f of the side rails 12 by a plurality of rivets 14, respectively.

The upper and lower flanges 16 of the cross member 16
The front free and rear free edges of the vehicle body f have an outer curved portion 16fb formed of a concave curve that expands outward toward the outside in the vehicle width direction.
And an inner curved portion 16f composed of a curve such as an arc, an ellipse, a parabola, or a hyperbola which is smoothly connected to the outer curved portion 16fb.
a.

[0033] The outer curved portion 16fb, the flange 1 from longitudinal center plane Y-O of the vehicle at a position _{P B} of the equivalent center of gravity G is substantially equidistant _{X B} of the plurality of rivets 14
A width _{Y B} longitudinal direction of 6f, between the longitudinal direction of the vehicle body width _{Y A} at the distance _X A _{= X} B / 2 becomes bisecting position _{P A} from the center plane _{Y-O, (Y} B / Y _A ) ² = 1.5-2.
5, and is preferably formed to have a distance L _G larger radius of curvature between 2 the relationship is set to stand by, and the center plane Y-O equivalent center of gravity G. The inner curved portion 16fa is connected to the outer curved portion 1
To the longitudinal direction of the width _{Y A} of both end portions to be connected to 6Fb,
Width Y _O of the center plane Y-O is set small.

FIG. 11 shows a seventh embodiment of the present invention. In this embodiment, an I-shaped substrate having substantially the same planar shape as the sixth embodiment is used.
The cross member 16 having the mold cross section has its upper and lower flanges 16f.
The gusset 18 is fixed to the corresponding upper and lower flanges 18f of the gusset 18 having a groove shape in cross section by a plurality of rivets 14, respectively. The gusset 18 is fixed to the web 12w of the adjacent side rail by a plurality of rivets 20. ing.

The upper and lower flanges 16 of the cross member 16
The front free and rear free edges of the vehicle body f have an outer curved portion 16fb formed of a concave curve that expands outward toward the outside in the vehicle width direction.
And an inner curved part 1 composed of an arbitrary curve such as an arc, an ellipse, a parabola, and a hyperbola smoothly connected to the outer curved part 16fb.
6fa.

The flange at the position _{P B} of the outer curved portion 16fb the equivalent center of gravity G is substantially equidistant _{X B} of the plurality of rivets 14 from longitudinal center plane Y-O of the vehicle 1
A width _{Y B} longitudinal direction of 6f, between the longitudinal direction of the vehicle body width _{Y A} at the distance _X A _{= X} B / 2 becomes bisecting position _{P A} from the center plane _{Y-O, (Y} B / Y _A ) ² = 1.5-2.
5, preferably set such that the relationship of 2 holds,
And the distance LG between the center plane YO and the equivalent center of gravity _G =
It is formed to have a X _B larger radius of curvature. The inner curved portion 16fa is connected to the outer curved portion 16f.
to the longitudinal direction of the width Y _A of both end portions to be connected to b, the width Y _O of the center plane Y-O is set small.

Regarding the sixth embodiment and the seventh embodiment,
When the stress generated in the cross member 16 was examined by performing a torsional test, the maximum stress was sufficiently low, and the stress was not concentrated on the connecting portion between the outer curved portion 16fb and the inner curved portion 16fa, as in the above-described embodiments. Therefore, it has been confirmed that the durability and reliability are excellent, and that the weight can be reduced by forming the central portion of the cross member as the inside curved portion 16fa as shown in the figure, and the manufacturing cost can be reduced correspondingly. .

Next, FIG. 12 shows the fifth to seventh embodiments.
14 shows a modification of the cross member 16 having the I-shaped cross section in the embodiment. As shown in the drawing, members 16a and 16b each having a groove shape in cross section are back-to-back, and both webs 16w are integrally connected by a plurality of rivets 22 to form an I-shaped cross member. When this assembly type cross member 16 was applied to the fifth to seventh embodiments, substantially the same effects as those described above were obtained in each embodiment.

FIGS. 13 and 14 show an eighth embodiment of the present invention. In this embodiment, an upper member 16u has a hat-shaped cross-section for most of the entire length except both ends in the vehicle width direction.
And a lower member 161 having a hat-shaped cross-section for the majority of the entire length except for both ends in the vehicle width direction, and integrally joined by a large number of rivets 24, and both ends of the upper member 16u and the lower member 161. An alligator type cross member 16 having a V-shaped connecting portion is used. The V-shaped connecting portion includes an upper member 16u and a lower member 161.
The mounting flanges 16u 'and 161' are formed by bending the end portions of the side rails in the vertical direction, and these mounting flanges 16u 'and 161' are fastened to the web 12w of the side rail 12 by a number of rivets 14. .

As shown in FIG. 13, the plan shape of the free edge of the cross member 16 extending in the vehicle width direction at the front and rear of the vehicle body is widened outward near both ends in the vehicle width direction. The outer curved portion 16fb is formed by an open concave curve, and the inner curved portion 16fa is formed by an arbitrary curve such as an arc, an ellipse, a parabola, and a hyperbola that is smoothly connected to the outer curved portion 16fb.

[0041] The outer curved portion 16fb is located a distance X _B had distance from longitudinal center plane Y-O from the equivalent center of gravity G is substantially coincident with the center plane Y-O of the plurality of rivets 14 of the vehicle the longitudinal direction of the vehicle body width in P _B and _{Y B,} when the longitudinal direction of the vehicle body width at the distance _X a _{= X} B / 2 only distance only position _{P a} from the center plane Y-O was _{Y a,} Y
Between the _B and ^{_{Y A (Y B / Y A}} ) 2 = 1.5~2.5,
Preferably 2 the relationship is satisfied, and the planar shape of the outer free edge of the cross member between P _A and P _B,
Distance L _G = X _B between center plane YO and equivalent center of gravity G
It is formed so as to form a concave curve having a larger radius of curvature. Also the inner curved portion 16fa, compared longitudinal width Y _A of both end portions to be connected to the outer curved portion 16Fb, width Y _O of the center plane Y-O is set small.

FIGS. 15 and 16 show a ninth embodiment of the present invention. In this embodiment, the vehicle width direction ends of the upper member 16u and the lower member 161 of the alligator-type cross member 16 having substantially the same planar shape as the eighth embodiment are respectively attached to the side rails 12 by a plurality of rivets 14.
Are fastened to the upper and lower flanges 12f.

As in the above embodiments, the cross member 16
The outwardly curved outer curved portion 16fb formed at both end portions in the vehicle width direction of the vehicle has a front-rear center plane YO of the vehicle.
The width of the vehicle body longitudinal direction and _{Y B} of the equivalent center of gravity G is substantially the same distance _{P B} of the rivet 14 group from the distance from the center plane _{Y-O X A = X B} / 2 only distance only position _{P A}
When the longitudinal direction of the vehicle body width was _{Y A} in, _(Y B /
Y _A) ² = 1.5 to 2.5, preferably is formed to 2 the relationship is established, and from the distance _L G = _{X B} between the center plane Y-O equivalent center of gravity G It is formed to have a large radius of curvature. Also, cross member 1
Inner curved portion 16fa of Kurumahaba center section of 6 to the longitudinal direction of the width Y _A of both end portions to be connected to the outer curved portion 16Fb, an arc as the width Y _O on the center plane Y-O is reduced , An ellipse, a parabola, a hyperbola, and other appropriate curves having a large radius of curvature.

FIGS. 17 and 18 show a tenth embodiment of the present invention. In this embodiment, the upper member 1 of an alligator-type cross member 16 having substantially the same planar shape as the ninth embodiment is shown.
6u and the end in the vehicle width direction of the lower member 161 are respectively fixed to the corresponding upper and lower flanges 18f of the gusset 18 having a groove-shaped cross-sectional shape by a plurality of rivets 14, and the gusset 18 is adjacent to the web 18w. It is fixed to the web 12 w of the side rail 12 by a number of rivets 20.

As in the above embodiments, the cross member 16
The outwardly curved outer curved portion 16fb formed in the outer portion in the vehicle width direction of the vehicle is formed with a front-rear center plane YO of the vehicle.
The width of the vehicle body longitudinal direction and _{Y B} of the equivalent center of gravity G is substantially the same distance _{P B} of the rivet 14 group from the distance from the center plane _{Y-O X A = X B} / 2 only distance only position _{P A}
When the longitudinal direction of the vehicle body width was _{Y A} in, _(Y B /
Y _A) ² = 1.5 to 2.5, preferably is formed to 2 the relationship is established, and from the distance _L G = _{X B} between the center plane Y-O equivalent center of gravity G It is formed so as to form a concave curve having a large radius of curvature. Also, an inner curved portion 16f at the center of the cross member 16 in the vehicle width direction.
a, compared longitudinal width Y _A of both end portions to be connected to the outer curved portion 16Fb, an arc as the width Y _O in the center plane Y-O is reduced, ellipse, parabola, hyperbolic, etc. curvature radius larger It is formed by an appropriate curve.

With respect to the ninth and tenth embodiments, the torsional test was performed to examine the generated stress of each part of the cross member 16. As a result, the generated stress was also found in the vicinity of the joint with the side rail 12 where the maximum stress normally occurs. The outer curved portion 16fb and the inner curved portion 16fa, respectively.
Are smoothly connected to each other, so that there is no problem that stress concentration occurs at the connection portion, and furthermore, the inner curved portion 16f at the center portion of the cross member where shear force in the front-rear direction is a problem.
regard a, the width _{Y O} on longitudinal center plane Y-O position X
It confirmed the absence of strength problem be set smaller than Y _A in _A. As a result, safety against rough roads and rough terrain travel is high, durability and reliability are excellent, and the weight of the cross member 16 can be effectively reduced, and the manufacturing cost is correspondingly reduced. There are advantages that can be.

The alligator type cross member 16
The upper member 16u and the lower member 161 extend over the entire length of the cross member, and the intermediate portion except for the V-shaped connecting portions at both ends in the vehicle width direction has a closed cross-sectional structure, and therefore has relatively high torsional rigidity. The lower member 16
1 is disposed only at both end portions of the upper member 16u to form a V-shaped connecting portion, and the alligator-type cross member having a relatively low torsional rigidity having an intermediate portion having an open cross-sectional structure including only the upper member 16u is also provided. There are the same advantages as above.

[0048]

As described above, the underframe for a vehicle according to the present invention is provided on the side rails extending in the longitudinal direction of the vehicle body.
The cross member extending in the vehicle width direction is fastened with a plurality of rivets at both ends thereof, wherein the cross member is separated from a center plane in the front-rear direction of the vehicle by a distance X in the vehicle width direction.
Position P near the equivalent center of gravity of the plurality of rivets separated by _B
The longitudinal direction of the vehicle body width and Y _B of _B, and the longitudinal direction of the vehicle body width at the position P _A and the distance X _{A =} X B / ₂ from the longitudinal center plane Kurumahaba direction have distance of the vehicle and Y _A, also, when the distance from the vehicle longitudinal center plane to the equivalent center of gravity was ^{_{L G, (Y B / Y}} a) a 2 = 1.5 to 2.5, and between the _{P a} and _{P B} the shape of the outer free end edge includes a concave-curved plane shape of the L _G of curvature greater than between, more planar shape of the inner free edge of inwardly from the outer free edge, in the outer free edge width Y _O in the vehicle longitudinal center plane characterized in that it is formed by the width Y _a smaller curve with a smooth connection, thereby improving the durability and reliability of the undercarriage frame such as a truck vehicle, Lower weight and lower manufacturing costs There are advantages that can be done.

[Brief description of the drawings]

FIG. 1 is a partial plan view of a chassis frame showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a sectional view similar to FIG. 2 showing a second embodiment of the present invention.

FIG. 4 is a partial plan view of a chassis frame showing a third embodiment of the present invention.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

FIG. 6 is a partial plan view of a chassis frame showing a fourth embodiment of the present invention.

FIG. 7 is a sectional view taken along the line VII-VII in FIG. 6;

FIG. 8 is a partial plan view of a chassis frame showing a fifth embodiment of the present invention.

9 is a cross-sectional view of the cross member 16 in FIG.

FIG. 10 is a partial plan view of a chassis frame showing a sixth embodiment of the present invention.

FIG. 11 is a partial plan view of an underframe showing a seventh embodiment of the present invention.

FIG. 12 is a cross-sectional view showing a modification of a cross member having an I-shaped cross section.

FIG. 13 is a partial plan view of an underframe showing an eighth embodiment of the present invention.

14 is a sectional view taken along the line XIV-XIV in FIG.

FIG. 15 is a partial plan view of a chassis frame showing a ninth embodiment of the present invention.

FIG. 16 is a sectional view taken along the line XVI-XVI in FIG.

FIG. 17 is a partial plan view of an underframe showing a tenth embodiment of the present invention.

FIG. 18 is a sectional view taken along the line XVIII-XVIII in FIG. 17;

FIG. 19 is a diagram illustrating an equivalent center of gravity G of a number of rivets.

[Explanation of symbols]

10 ... chassis frame, 12 ... side rail, 14 ... rivet, 16 ... cross member, 18 ... gusset

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B62D 21/02

Claims (1)

(57) [Claims] 1. A vehicle comprising: a side rail extending in the vehicle longitudinal direction; and a cross member extending in the vehicle width direction fastened to both ends by a plurality of rivets. the longitudinal direction of the vehicle body width at the position P _B of the equivalent near the center of gravity of the plurality of rivets distance X _B from the center plane Kurumahaba direction had distance and Y _B, distance Kurumahaba direction from longitudinal center plane of the vehicle the width of the vehicle body longitudinal direction and _{Y a} in the _{X a} = X B / 2 and the have distance position _{P a,}
Also, when the distance from the vehicle longitudinal center plane to the equivalent center of gravity was ^{_{L G, (Y B / Y}} A) 2 = 1.5~2.
5 is a, and the P _A and the outer shape of the free end edge includes a concave-curved plane shape of the L _G greater curvature, further inside the inner from the outer free edge between P _B the planar shape of the free end edge, width Y _O in the vehicle longitudinal center plane with smoothly connected to the outer free edge is above Y _a
A chassis frame for a vehicle, characterized by being formed by a smaller curve.