JPH0790795B2 - Undercarriage frame for vehicle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a chassis frame for a vehicle 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. A chassis frame composed of individual cross members is provided, and a front axle and a rear axle are attached to the chassis frame via suspension devices, and a cab, an engine, a luggage carrier, etc. are mounted.

The cross member may be a member having a groove-shaped cross section, a member having an I-shape, or a so-called alligator-type cross member having V-shaped expansion portions at both ends connected to the side rails. Has been adopted.

(Problems to be Solved by the Invention) When a vehicle such as a truck travels at high speed on a bad road having severe unevenness in an overloaded state, a large torsional load acts on the vehicle body frame, and the cross member, especially the side member, acts on the cross member. Large stress is generated near the joint with the rail. A typical configuration of the side rail and cross member connecting portions in the conventional chassis frame will be described with reference to FIG. 18. In the figure, reference numeral 10 generally indicates a chassis frame, and the chassis frame includes left and right extending in the front-rear direction of the vehicle body. The pair of side rails 12 has a groove-shaped cross section. (Only the left side rail is shown in the figure) A gusset 14 having a groove-shaped cross-section is inserted into the side rail 12, and the gusset 14 has its web 14w attached to the web 12w of the side rail by a large number of rivets. It is fixed by 20. 16 is a cross member having a groove-shaped cross section, and the upper and lower flanges 16
The width Y ₀ of f in the vehicle front-rear direction (the y direction in the drawing) is substantially the same over the entire length in the vehicle width direction (the x direction in the drawing), and both ends of the f and bottom flanges of the gusset 14 are connected to each other.
It is fixed to 14w by many rivets 18.

The chassis frame 10 including the cross member 16 was subjected to a torsion test to examine the stress generated at the free edge of the cross member flange 16f, and the result shown by the dotted line S ₁ in FIG. 17 was obtained. In FIG. 17, the vertical axis represents the generated stress σkgf / mm ² , and the horizontal axis represents the vertical plane that passes through the center line of the cross member 16 in the vehicle front-rear direction, in other words, the distance x from the vehicle symmetry plane, x ₁ is the intersection with the gusset 14 above,
Further, x ₂ indicates the outer ends of the cross member 16 in the vehicle width direction, respectively. Flange 16f, as shown by curve S ₁ above
The stress generated at the edge of the vehicle gradually increases as it moves away from the vehicle symmetry plane outward in the vehicle width direction, and the point of intersection with the gusset 14 x ₁
The maximum value is reached, and then it decreases rapidly toward the outer edge x ₂ in the vehicle width direction, but large stress occurs near the intersection x ₁ with the gusset 14, and defects such as cracks are likely to occur at this portion. It was confirmed.

An object of the present invention is to reduce the stress generated in the vicinity of the joint with the side rail in the cross member of the chassis frame, effectively avoid the damage of the cross member, and improve the durability and reliability of the chassis frame. It is what

(Definition) In the present specification, the term "equivalent center of gravity" is defined as follows with respect to a plurality of rivets that fix both ends of the cross member in the vehicle width direction to the side rails with or without gussets. It is a thing.

That is, in FIG. 6, an arbitrary number (two or more) of rivets R ₁ , R
₂ ... R _i ... R _n the lateral elastic modulus of G ₁ , G ₂ ... G _i ... G _n , and the cross-sectional area of each rivet a ₁ , a ₂ ... a _i ... a _n , and x of each rivet.
Assuming that the coordinates and the y coordinate are x ₁ , x ₂ … x _i … x _n and y ₁ , y ₂ … y _i , respectively, the x coordinate x _g and the y coordinate y _g of the equivalent center of gravity G are respectively expressed as follows. Be done.

(Means for Solving the Problems) A chassis frame for a vehicle according to the present invention was created to achieve the above object, and is a web of a side rail that extends in the vehicle front-rear direction and has a groove-shaped cross section. In a structure in which both ends of a cross member extending in the vehicle width direction are fastened with a plurality of rivets, the cross member is
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 and the distance X _B have distance from the vehicle symmetry plane Kurumahaba direction and Y _B, a distance X _A in the Kurumahaba direction from the vehicle plane of symmetry = X _B
Assuming that the width in the front-rear direction of the vehicle body at a position P _A at a distance of / 2 is Y _A , (Y _B / Y _A ) ² = 1.5 to 2.5, and the above P _A and P
_It is characterized in that the shape of the free edge between _B and _B has a planar shape that linearly expands outward in the vehicle width direction.

(Operation) According to the present invention, the plane shape near the connecting end of the cross member with the side rail is changed to the special shape described above, that is, the width Y _B in the vehicle body front-rear direction at the position X _B near the equivalent gravity center position of the plurality of rivets.
And the width Y _A in the vehicle front-rear direction at the bisecting position X _A between the vehicle symmetry plane and the position X _B (Y _B / Y _A ) ² = 1.5 to 2.
5 and the shape in which the width in the vehicle front-rear direction at each intermediate position from the position X _A to Y _B changes linearly from Y _A to Y _B , the side of the cross member is The maximum stress generated in the vicinity of the rail joints is greatly reduced, and the both end portions of the cross member in the vehicle width direction are fastened to the side rail webs by rivets to improve the durability and overall durability of the chassis frame. The reliability can be improved.

EXAMPLES Examples of the present invention will be specifically described below with reference to the accompanying drawings. (Note that members or portions substantially the same as or corresponding to those of the conventional configuration described with reference to FIG. 18 are denoted by the same reference numerals, and duplicate description will be omitted.) First, FIG. In the first embodiment of the invention shown in FIGS. 3 and 4,
The cross member 16 has a vertical flange 16f formed by extending its upper and lower flanges 16f outward in the vehicle width direction and bending them at right angles.
The vertical flange 16f 'is fixed to the web 12w of the side rail 12 by a plurality of rivets 18. Since the plurality of rivets 18 are arranged on the web 12w of the side rail 12, their equivalent center of gravity G and the vehicle symmetry plane yO are shown.
The distance l _G / 2 between and is substantially equal to one half of the total length of the cross member 16 in the vehicle width direction, that is, the x direction.

As shown in the figure, the plane shape of the cross member 16, that is, the shape of the upper and lower flanges 16f is such that the front-rear width of the vehicle body is substantially equal to Y _A from the vehicle symmetry plane yO to the intermediate position P _A in the vehicle width direction. The width in the front-rear direction of the vehicle body is linearly enlarged to Y _B from the position P _A to a position P _B near the outer end in the vehicle width direction. More specifically, 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) in the vehicle width direction, and the intermediate position P _A has a distance X _A from the vehicle symmetry plane yO. 1/2 of the distance X _B from the vehicle symmetry plane yO of _B, and is set to bisection point of the straight line OP _B in Figure 1 in other words.
The widths Y _A and Y _B at the positions P _A and P _B are formed so that the relationship (Y _B / Y _A ) ² = 2 holds.

Undercarriage frame including the cross member 16 having the above shape
No. 10 was subjected to a torsion test under the same conditions as the conventional chassis frame shown in Fig. 18, and the upper and lower flanges of the cross member were
When the stress generated at the free edge of 16f was measured,
As shown by the solid line S ₂ in Fig. 7, the maximum stress generated near the joint with the side rail 12 is sufficiently reduced, and therefore the safety is high against running on a bad road in an overloaded state. It was confirmed that durability and reliability can be remarkably improved.
Further, FIG. 4 shows that when the cross member 16 is joined to the web 12w of the side rail 12 by the rivet 18, a vertical flange 16w 'is formed on the web 16w of the cross member 16 and the vertical flange 16w' is formed on the side rail. First combined with web 12w
Although this is a modification of the embodiment, even with this configuration, the maximum stress of the cross member flange 16f can be reduced substantially similarly to the case of FIG.

The width Y of the cross member flange 16f in the front-rear direction of the vehicle body
_When Y _B was variously changed with respect to _A , the above (Y _B / Y _A ) ² = 2 was optimal, and when this value was 2.5 or more, the stress reduction effect peaked out and the weight increase to the people. However, it was confirmed that when the above value was 1.5 or less, the stress reducing effect was not sufficient and the anxiety about strength increased. Further, vertical flanges at both ends of the cross member 16 in the vehicle width direction
By fastening the 16f 'or 16w' to the web 12w, which has a relatively small generated stress, by the rivet 18, instead of the upper and lower flanges of the side rail 12, which has an essentially large generated stress,
The durability of the side rails 12 has been improved, and the above-mentioned cross members 16
Combined with the stress reduction effect of 1., there is an advantage that the durability and reliability of the entire chassis frame can be greatly improved.

Next, FIGS. 2 and 5 show a second 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 having the same plane shape as the first embodiment are fixed to the corresponding flanges 14f of the gusset 14 having the groove-shaped cross section by a plurality of rivets 18. The above gusset 14
The web 14w is fixed to the adjacent side rail web 12w by rivets 20. A width Y _B of the flange 16f in the vehicle front-rear direction at a position P _B substantially equidistant from the vehicle symmetry plane yO to the equivalent center of gravity G of the plurality of rivets 18 and X _B ;
(Y _B / Y _A ) ² = 1.5 ~ between the width Y _{A in the} longitudinal direction of the vehicle body at the bisecting position P _{A where} the distance X _A = X _B / 2 from the vehicle symmetry plane y O
The dimensions of each part are determined so that the relationship of 2.5, preferably 2, is established.

When a stress test was conducted on the free edge of the cross member flange 16f by conducting a torsion test on the second embodiment described above, results similar to the curve S ₂ in FIG. 17 were obtained, and the joint with the side rail 12 was obtained. It was confirmed that the maximum stress generated in the flange 16f in the vicinity can be effectively reduced as compared with the conventional case.

FIG. 7 shows a third embodiment of the present invention. In this embodiment, a cross member 16 having an I-shaped cross section as shown in FIG. 9 is used. The cross member 16 has vertical flanges 16f, which are formed by extending the upper and lower flanges 16f outwardly and bending them in the vertical direction, and fixed to the webs 12w of the side rails by a plurality of rivets 18 in the same manner as in FIG. .

The cross member 16 has an equivalent center of gravity G of the rivets 18.
The width in the vehicle front-rear direction of the flange 16f at the position P _{B, which} is located slightly closer to the vehicle symmetry plane yO and whose distance from the symmetry plane yO is X _B , is Y _B, and the distance from the vehicle symmetry plane yO is X _A = X when the longitudinal direction of the vehicle body width of the flange 16f and the Y _a in the _B / 2 only distance only position _{P a, (Y B / Y} a) between the Y _B and Y _a 2 ⁼ 1.5 to 2.
5, preferably, the relationship of 2 is established, and the flange 16f is formed to have a planar shape in which it linearly expands between P _A and P _B.

As described above, a chassis frame having a cross member 16 having a planar shape in which the vicinity of the joint with the side rail 12 is linearly expanded outward, and a normal width in the vehicle front-rear direction is substantially equal over the entire length. A chassis frame having a cross member having an I-shaped cross section was subjected to a torsion test under substantially the same conditions, and the stresses generated at the free edges of the upper and lower flanges 16f of the cross member were compared with each other. Similarly, it was confirmed that the maximum stress was remarkably reduced as compared with the conventional one having the same kind of cross member, and therefore the durability and reliability could be effectively improved.

Further, FIG. 8 shows a fourth embodiment of the present invention. In this embodiment, a cross member 16 having an I-shaped cross section having the same plane shape as that of the third embodiment has a groove-shaped cross section in which the upper and lower flanges 16f are provided. Each gusset 14 has its corresponding flange 14f secured to each by a plurality of rivets 18, and the gusset 14 has its web 14w secured to a web 12w of an adjacent side rail by a rivet 20. The width Y _B of the flange 16f in the longitudinal direction of the vehicle body at a position P _B substantially equidistant from the plane of symmetry yO of the vehicle and the equivalent center of gravity G of the plurality of rivets 18 and X _B ;
(Y _B / Y _A ) ² = 1.5 ~ between the width Y _{A in the} longitudinal direction of the vehicle body at the bisecting position P _{A where} the distance X _A = X _B / 2 from the vehicle symmetry plane y O
The dimensions of each part are determined so that the relationship of 2.5, preferably 2, is established.

A torsion test was conducted on the above-mentioned fourth embodiment to check the stress generated at the free edge of the cross member flange 16f.
When the width of 6f in the front-rear direction of the vehicle body is substantially equal over the entire length in the vehicle width direction, and compared with the stress generated at the flange free end edge of the cross member having a normal I-shaped cross section, the curve S _{2 in} FIG.
A result similar to S ₁ was obtained, and in the fourth embodiment,
It has been found that the maximum stresses generated are significantly reduced, and thus improved durability and reliability are effectively achieved. Further, instead of the cross member 16 having a so-called integral I-shaped cross-section as shown in FIG. 9, members 16a and 16b having a groove-shaped cross-section as shown in FIG. 10 are placed back to back. It was confirmed that substantially the same effect can be obtained also in the assembled cross member 16 in which the I-shaped cross section is formed by integrally connecting the rivets 22 with each other.

FIG. 11 shows a fifth embodiment of the present invention.
As shown in FIG. 13, an upper member 16u, which has a hat-shaped cross-section for most of its entire length excluding both ends, and a lower member 16l, which is a flat plate, are integrally connected by a large number of rivets 24. , With the closed cross-section structure for almost the entire length excluding both ends,
At both end portions, an alligator type cross member 16 is used in which the upper member 16u and the lower member 16l are expanded in a V shape and mounting flanges 16u 'and 16l' are formed at the respective tips. The cross member 16 is fixed to the side rail 12 by fastening the mounting flanges 16u 'and 16l' to the side rail web 12w with a plurality of rivets 18.
(Note that the lower member 16l of the cross member 16 is replaced by the upper member 16u.
Similarly, a member having a hud-shaped cross section may be formed, and both members may be faced to each other and integrally coupled by a rivet 24 to form the cross member 16. ) The cross member 16 has an equivalent center of gravity G of the plurality of rivets 18.
Position the distance X _B had distance substantially matched vehicle symmetry plane yO and
Let Y _B be the width in the front-rear direction of the vehicle body at P _B,
When the distance X _A = X _B / 2 only the longitudinal direction of the vehicle body width in distance only position P _A and a Y _A from yO, between the Y _B and Y _A (Y _B / Y _A)
= 1.5 to 2.5, preferably 2, and the plane shape of the cross member is linearly expanded and formed into a V shape between P _A and P _B.

Under substantially the same conditions, the chassis frame including the cross member 16 having a planar shape as described above and the chassis frame including the normal alligator-type cross member having substantially the same width in the longitudinal direction of the vehicle body over the entire length thereof. A stress test was conducted on the front and rear edges of the cross member by performing a twisting test with, and in the same manner as in the case of the groove-shaped cross member and the I-shaped cross member, the maximum stress is higher in the present embodiment than in the conventional one. Was significantly reduced, and therefore, improvement in durability and reliability was achieved.

12 and 14 show the ninth embodiment of the present invention, and FIG. 6 shows the ninth embodiment of the present invention. In this embodiment, the upper member of the alligator type cross member 16 having the same plane shape as that of the fifth embodiment.
16u and the lower member 16l end portions in the vehicle width direction are fixed to corresponding flanges 14f of a gusset 14 having a groove-shaped cross section by a plurality of rivets 18, and the gusset 14 has its webs 14w adjacent to side rails. Is fixed to the web 12w of the same by rivets 20. The cross member 16 is
From the vehicle symmetry plane yO, the width in the vehicle front-rear direction at the position P _B substantially equidistant to the equivalent center of gravity G of the plurality of rivets 18 and X _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 vehicle plane of symmetry yO was Y _A, Y _B
And Y _A are formed so that the relation (Y _B / Y _A ) ² = 1.5 to 2.5, preferably 2, holds.

When a stress test was conducted on the front and rear end edges of the cross member by conducting a torsion test on the sixth embodiment, the maximum stress generated near the joint with the side rail 12 was larger than that of the prior art as in the fifth embodiment. It is recognized that Further, in the alligator-type cross member 16 shown in FIGS. 13 and 14, the upper member 16u and the lower member 16l extend along the entire length of the cross member, and the V-shaped members at both ends in the vehicle width direction are provided. It has a relatively high torsional rigidity with a closed cross section formed in the middle part except the part.
As shown in Figure 15, the lower member 16l is replaced by the upper member 16u.
In the alligator-type cross member 16 having a relatively low torsional rigidity, the V-shaped joint is fixed to only the end of the cross member, and thus the middle portion of the cross member is composed of only the upper member 16u having an open cross section. Also, substantially the same effect can be obtained.

Next, in a seventh embodiment of the present invention shown in FIG. 16, two cross members 16 having the same groove type cross section as the first and second embodiments are arranged side by side with a gap C in the vehicle front-rear direction. The gap C is, for example, 30 mm to 80 mm. Each cross member 16 has its upper and lower flanges 16f, and a plurality of rivets 18 on the upper and lower flanges 14f of a common gusset 14 having a groove-shaped cross section.
The gusset 14 has its web 14w fixed to the side rail web 12w by a large number of rivets 20.

Also in this embodiment, by configuring each cross member 16 in the same manner as in the second embodiment shown in FIG. 2, the maximum stress generated at the free edge of each cross member flange 16f can be reduced respectively. Therefore, damage to the cross member can be effectively prevented and its durability and reliability can be improved. Even when the two cross members 16 arranged side by side are fastened to the web 12w of the side rail 12 by a plurality of rivets 18, as in the first embodiment shown in FIG.
By forming the cross-sectional shape of each cross member 16 substantially in the same manner as in FIG. 1, the same effect as in the first embodiment can be obtained.

In all of the above-mentioned embodiments, even if the cross member 16 is bent in the vertical direction in order to avoid interference with the differential, the propeller shaft, etc., the effects and advantages of the present invention are substantially unchanged.

(Advantages of the Invention) As described above, the vehicle undercarriage frame according to the present invention has a cross member that extends in the vehicle width direction on a web of a side rail that extends in the vehicle front-rear direction and has a groove-shaped cross section. Where the both ends of the rivet are fastened together by a plurality of rivets, the cross member is located in the vicinity of the equivalent center of gravity of the plurality of rivets at a distance X _B from the vehicle symmetry plane in the vehicle width direction.
When the width in the front-rear direction of the vehicle body at P _B is Y _B, and the width in the front-rear direction of the vehicle body at a position P _A at a distance X _A = X _B / 2 in the vehicle width direction from the above vehicle symmetry plane is Y _A , (Y _B / Y _A ) ² = 1.5 to 2.
5, and the shape of the free edge between P _A and P _B has a planar shape that linearly expands outward in the vehicle width direction. In particular, the stress generated in the cross member during high-speed running on bad roads in an overloaded state can be effectively reduced and damage can be prevented, and both ends of the cross member in the width direction of the vehicle can be attached to the side rail web. Since the side rails can be prevented from being damaged by fastening, there is an advantage that the durability and the reliability of the chassis frame can be improved together.

[Brief description of drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention, FIG. 2 is a plan view showing a second embodiment of the present invention, and FIG. 3 is a III of FIG.
-A sectional view taken along the line III in the direction of the arrow, Fig. 4 is a similar sectional view showing a modification of Fig. 3, and Fig. 5 is V- in Fig. 2.
A sectional view taken along the line V in the direction of the arrow, FIG. 6 is a diagram for explaining the equivalent center of gravity of a plurality of rivets, and FIG. 7 is a third view of the present invention.
FIG. 8 is a plan view showing an embodiment, FIG. 8 is a plan view showing a fourth embodiment of the present invention, FIG. 9 is a cross-sectional view of a cross member in the third and fourth embodiments, and FIG. 10 is shown in FIG. FIG. 11 is a sectional view showing a modified example of the cross member, FIG.
FIG. 12 is a plan view showing an embodiment, FIG. 12 is a plan view showing a sixth embodiment of the present invention, FIG. 13 is a sectional view taken along the line XIII-XIII in FIG. FIG. 12 is a cross-sectional view taken along the line XIV-XIV in the direction of the arrow, FIG. 15 is a partial side view showing a modification of the alligator-type cross member 16 in FIGS. 13 and 14, and FIG. 16 is the present invention. FIG. 17 is a plan view showing the seventh embodiment of
The drawing is a diagram showing the stress generation mode of the cross member 16 in the first embodiment in comparison with the conventional device shown in FIG.
FIG. 18 is a partial plan view showing a typical configuration of a conventional chassis frame. 10 ... Chassis frame, 12 ... Side rail, 16 ... Cross member, 18 ... Rivet, G ... Rivets Equivalent center of gravity of 18 groups.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Hanakiuchi 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Kunio Hara 5-33-8 Shiba, Minato-ku, Tokyo Within Mitsubishi Motors Corporation (56) References: 60-124381 (JP, U), 62-153182 (JP, U)

Claims (1)

[Claims] 1. A structure in which both ends of a cross member extending in the vehicle width direction are fastened to a web of a side rail extending in the vehicle body direction and having a groove-shaped cross section by a plurality of rivets, respectively. said cross member, and the width of the vehicle body front-rear direction Y _B at the position P _B of the equivalent near the center of gravity of the plurality of rivets and the distance X _B have distance to Kurumahaba direction from the vehicle plane of symmetry, Kurumahaba from the vehicle plane of symmetry Position at a distance of X _A = X _B / 2 in the direction
When the width in the front-rear direction of P _A is Y _A (Y _B / Y _A )
² = 1.5 to 2.5, and the shape of the free edge between P _A and P _B has a planar shape that linearly expands outward in the vehicle width direction. Vehicle chassis frame