JPH0813665B2 - Truck underframe - Google Patents

Description

TECHNICAL FIELD The present invention relates to a chassis frame of a truck.

(Terms) In this specification, the term "equivalent center of gravity" has the following meaning with respect to a plurality of rivets or bolts for fastening both ends of the cross member in the vehicle width direction to the gusset. That is, in FIG. 9 of the accompanying drawings, an arbitrary number n (however, n ≧ 2)
Of rivets or bolts R ₁ , R ₂ … R _i … R _n-1 , R _n are the transverse elastic modulus of G ₁ , G ₂ … G _i … G _n-1 , G _n , respectively Let the husbands a ₁ , a ₂ ... a _i ... a _n-1 , a _n , and the coordinate vector of each rivet or bolt be ₁ , ₂ ... _i ... _n-1 , _n , the coordinate vector of the equivalent center of gravity g _g is represented by the following equation. That is (Prior Art) An ordinary truck has a pair of left and right side rails each having a groove-shaped cross section and extending in the front-rear direction of a vehicle body, and a plurality of 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 cap, an engine, a luggage carrier, etc. are mounted.

As the cross member, a member having a groove-shaped cross section, a member having an I shape, and a so-called alligator type cross member having V-shaped expansion portions formed at both end portions coupled to the side rails are appropriately adopted. Further, these cross members are often connected to the side rails at their both ends via gussets.

(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 shear stress is generated in the rivet or bolt that fastens both ends of the cross member to the gusset.

A typical structure of the connecting portion of the cross member and the gusset in the conventional chassis frame will be described with reference to FIG. 10. In the figure, reference numeral 10 generally indicates a chassis frame, and the chassis frame is a longitudinal direction of the vehicle body. A pair of left and right side rails 12 extending in the shape of a groove and having a groove-shaped cross section, and a cross member 14 extending in the vehicle width direction and having a groove-shaped cross section. The cross member 14 has the upper flange and the lower flange 14f at the ends in the vehicle width direction, the corresponding upper and lower flanges 16f of the gusset 16 having a groove-shaped cross section.
A plurality of (4 in the case shown) rivets 18 or bolts of substantially the same effect.
16 is loaded into the side rail 12 and its web 16w
Side rails 12 with multiple rivets 20 or bolts
It is fastened to the web 12w.

In a typical chassis frame 10, the distance from the equivalent center of gravity g of the bolt group of the rivet 18, or substantially the same effect to the center line of each rivet 18 or bolts expressed in r _i, the minimum value of r _i
When r _min and the maximum value are r _max , the value of r _min / r _max is about 0.3.
Rivets or bolts in the range of ~ 0.45 and often of the same diameter and material are placed. In the case shown, 4
The individual rivets 18 or bolts are arranged in an L shape, and the variation of the distance r _i from the equivalent center of gravity g is large, and r _min / r _max is about
It is a low value of 0.3 and the average value of r _i is also small.

As an example, a cross member 1 made of 6 mm thick steel plate
4 and gusset 16 made of 8 mm thick steel plate with a diameter of 13 mm
The rivet 18 is fastened by the four rivets 18 and the web 16w of the gusset 16 is joined to the web 12w of the side rail 12 made of a steel plate having a thickness of 8 mm by the rivet 20 having a diameter of 13 mm. FIG. 11 shows the result of the torsion test performed on the chassis frame arranged in such an L shape so that r _min / r _max = 0.3. In the torsion test, the rear portions of the left and right side rails 12 of the chassis frame, that is, the rear shackle pin bracket portions of the rear suspension springs are fixed, and the rear shackle pin bracket attachment portions of the front suspension springs have the same left and right directions but opposite directions. A force of (upward on one side and downward on the other side) is applied to repeatedly generate torsional displacement with a torsion angle of 4 ° in the chassis frame, and the maximum shear stress τ (kg / mm ² ) of the rivet group and the rivet and cross member are Endurance of each rivet (○ in the figure) and crossmember endurance (△ in the figure) until it breaks
This is a survey of N.

As is clear from the curve S indicating the maximum shear stress shown by the dotted line in the figure, in the conventional rivet arrangement shown in FIG. 11 where r _min / r _max = 0.3, the maximum shear stress τ is about 18 kg / mm. ^The number of rivets has reached ^2, and the number of rivets N is extremely low. The rivet or bolt breaks early or is adjacent to the rivet or bolt due to long-term operation under extremely severe driving conditions as described above. It was confirmed that defects such as cracks were likely to occur in the plate member of the cross member 14 or the gusset 16 that was formed. (Note that in the above test example, the thickness of the gusset 16 is greater than the thickness of the cross member 14, so the cross member 14 is damaged.
16 damage may occur, and in order to prevent damage to the rivet or bolt group, or damage to the side rail or cross member plate material that cooperates with these, it is necessary to add several layers to the parts that are conventionally unsatisfactory in strength as necessary. In addition, measures such as increasing the number of rivets or bolts to be used by interposing a reinforcing plate are conventionally taken.However, this leads to an increase in vehicle weight, a reduction in effective load capacity, and a reduction in fuel consumption. There was a drawback that caused disadvantages such as deterioration.

The present invention relates to an undercarriage frame in which both ends of a cross member are connected to side rails through gussets, and by reducing shear stress generated in rivets or bolts for fastening the crossmember to the gusset, durability of the undercarriage frame is reduced. It is intended to improve the reliability and reliability and at the same time achieve the weight reduction.

(Means for Solving the Problems) A chassis frame of a truck according to the present invention was created in order to achieve the above-mentioned object, and has a pair of left and right sides that have a groove-shaped cross section and extend in the vehicle front-rear direction. Rails,
A gusset fixed to the side rail by a plurality of rivets or bolts inserted inside the side rail,
A rivet or bolt group for fastening the cross member to the gusset, the cross member having a cross member secured to the gusset by a plurality of rivets or bolts, the both ends extending in the vehicle width direction. the distance from the equivalent center of gravity to the center line of the rivet or bolt and r ₁ of, when the minimum value of the r ₁ and r _min, the maximum value r _max, 0.5
The rivets or bolts are arranged so as to satisfy ≦ r _min / r _max ≦ 1, the distance from the vehicle center plane of the equivalent center of gravity to lg / 2, and the rivet or bolt group in the vehicle width direction. At least _one of the maximum separation distance x ₁ and the maximum separation distance y _{1 in} the longitudinal direction of the vehicle body is characterized by being set to 1.15 lg or more.

(Operation) According to the present invention, a plurality of rivets or bolts for fastening both ends of the cross member to the gusset are arranged with a small distance difference from the equivalent center of gravity as described above, and a vehicle of the rivet or bolt group. At least one of the maximum separation distance in the width direction and the maximum separation distance in the vehicle front-rear direction, or both,
When the distance from the vehicle center plane to the equivalent center of gravity is lg / 2, by setting it to 0.15lg or more, the load due to the torsion of the chassis frame is carried by each rivet or bolt more evenly than in the conventional arrangement. Therefore, the maximum shear stress is correspondingly reduced.

(Embodiment) An embodiment of the present invention will be specifically described below with reference to FIGS. 1 to 8. (Note that members and portions that are substantially the same as or correspond to those of the conventional configuration described with reference to FIG. 10 are denoted by the same reference numerals, and duplicate description will be omitted.) First, the first
In the first embodiment of the present invention shown in FIGS. 2 and 3, the cross member 14 having a groove-shaped cross-section has four rivets 18 (or four ends) on both ends of the upper flange 14f and the lower flange 14f. Bolts) which are fastened to the corresponding upper and lower flanges 16f of the groove type gusset 16 respectively, and the gusset 16 has its web 16w attached to the side rails by a large number of rivets 20 (or bolts of the same effect).
It is fastened to 12 webs 12w.

In the illustrated case, the distances r _i from the equivalent center of gravity g of the rivet group 18 to the center line of each rivet are all equal, and therefore the ratio of the minimum value r _min and the maximum value r _{max of} r _i , that is r _min / r _max = Each rivet is arranged so as to be 1. Further, compared with the conventional configuration of FIG. 10, the dimension of the upper flange and the lower flange 16f of the gusset 16 in the vehicle width direction, that is, the x direction in the figure is formed to be considerably large, and the maximum separation in the x direction of the rivet 18 group is made. The distance (indicated by x ₁ in the figure) is large enough that the average distance r _im (equal distance in this case) from the center of gravity to the center of each rivet is large enough. The maximum separation distance x ₁ of the rivets 18 in the x direction is 0.15lg when the distance from the center plane of the chassis frame 10 in the vehicle front-rear direction, that is, the vehicle symmetry plane yO to the equivalent center of gravity g is lg / 2. The above is set, that is, x ₁ ≧ 0.15 lg, and thus the average distance r _im is arranged to be sufficiently larger than in the past.

With respect to the chassis frame 10 having the above structure, a torsion test was conducted under substantially the same conditions as those of the conventional chassis frame shown in FIG. 10, and the maximum shear stress of the rivet 18 group and the number of times of durability of the cross member 14 and the gusset 16 were determined. When I looked it up,
As shown by the dotted curve S in FIG. 11, the maximum shear stress τ is reduced to about 12 kg / cm ² , and the durability number N of the rivet 18 and the cross member 14 is remarkably increased as compared with the conventional one, and thus the severeness is severe. It has been confirmed that the safety is extremely high under various running conditions, the durability and the reliability are effectively improved, and at the same time, the weight reduction can be achieved. In the above configuration,
When the same test was conducted by changing the arrangement of the rivet 18 and sequentially changing it from r _min / r _max = 0.5 to 0.9, the maximum shear stress τ and the durability number N of the rivet 18 and the cross member 14
The results shown in FIG. 11 were obtained for each of the above, and it was confirmed that each of them was superior to the conventional chassis frame. The above results show that the rivet or bolt group is 0.5 ≤ r _min /
By arranging so that r _max ≦ 1 is satisfied, the variation in the magnitude of the shearing force acting on the rivets or bolts in the above group is reduced, and the maximum separation distance x in the vehicle width direction of the rivet or bolt group x By setting ₁ to 0.15 lg or more, it is determined that the average value becomes small until the variation in shearing force is small as described above.

Next, in the second embodiment of the present invention shown in FIG. 3, a plurality of rivets 18 (four in the illustrated case) are provided at both ends in the vehicle width direction of the upper flange and the lower flange 14f of the groove type cross member 14.
(Or a bolt of the same effect) for the upper and lower flanges of the gusset 16.
Fastened to 16f, the gusset 16 webber 16w side rail
The basic structure in which a large number of rivets 20 (or bolts having the same effect) are fastened to the twelve webs 12w is essentially the same as that of the first embodiment. The difference from the first embodiment is that the connecting portions at both ends of the upper flange and the lower flange 14f of the cross member are enlarged in the vehicle longitudinal direction, that is, in the y direction in the figure,
Upper flange and lower flange 16f of gusset 16
Is at the point of being enlarged in the y direction. Four rivets 18 for fastening the flanges 14f and 16f are arranged spread in the y-direction, the maximum distance is y _1, and the distance from the equivalent center of gravity g of the rivet 18 group to the center line of the rivet r _i is the ratio rr _min / r _max of the maximum value r _min and a maximum value r _max of,
In the case shown, it is about 0.8. Similar to the first embodiment, the separation distance y ₁ is 0.15 lg or more, where lg / 2 is the distance from the center plane of the chassis frame 10 in the longitudinal direction of the vehicle body, that is, the vehicle symmetry plane yO to the equivalent center of gravity g. It is set so that y ₁ ≦ 0.15lg, and each rivet 18 has an average distance r from the equivalent center of gravity g.
_im is arranged so as to be sufficiently larger than the conventional configuration shown in FIG.

The chassis frame 10 having the above structure was subjected to the same torsion test as in the first embodiment, and r _min / r in FIG.
_The maximum shear stress τ corresponding to _max = 0.8 and the durability number N of the rivet 18 and the cross member 14 are obtained, and r _min / r _max is
As a result of performing the same torsion test with various changes in the range of 0.5 to 1.0, the same results as the maximum shear stress and the number of durability of the first embodiment shown in FIG. 11 were obtained over the whole. . Therefore, it has been confirmed that the rivet arrangement in the second embodiment can effectively improve the durability and reliability of the chassis frame and reduce the weight of the chassis frame. The result is that, as in the first embodiment, the rivet or bolt group is arranged so as to satisfy 0.5 ≦ r _min / r _max ≦ 1. the variation in size is reduced, further the maximum distance y ₁ in the longitudinal direction of the vehicle body of the rivet or bolt group
By setting it to 0.15 lg or more, it is judged that it is based on the fact that the average value becomes small while the variation in shearing force remains small as described above.

Further, in the third embodiment of the present invention shown in FIGS. 4 and 5, two groove-shaped cross-section members are abutted back to back at the web portion and integrally formed by rivets 22 or the like. The I-shaped cross-member 14 is used,
The cross member has its upper and lower flanges.
Both end portions of 14f in the vehicle width direction are attached to the upper flange 16f of the gusset extending in the vehicle width direction in the same manner as in the first embodiment by a plurality of (four in the illustrated case) rivets 18 (or bolts of the same effect). The same gusset 16 has its webber 16w
Is fastened to the web 12w of the side rail 12 by a large number of rivets 20. The distances r _i from the equivalent center of gravity g of the rivet 18 group to the center line of each rivet are all equal, and therefore the ratio r _min / r _max of the maximum value r _min and the maximum value r _{max of} r _i is 1
And the maximum separation distance x ₁ of the rivet group in the x direction
Is set to x ₁ ≧ 0.15lg as in the first embodiment.

The chassis frame 10 having the above-mentioned structure and the conventional chassis frame in which the rivet 18 having the same structure is arranged in the range of r _min / r _max = 0.3 to 0.45 are subjected to the torsion test in the manner described above, and the rivet 18 group The maximum shear stress τ and the number of times the rivet and cross member 14 were durable were examined.
The results obtained are approximately similar to the maximum shear stress and the number of times of endurance N shown in the figure, and the arrangement of the rivet 18 in FIG.
_{The same} was true when the value was changed within the range of _min / r _max = 0.5 to 0.9.

Although not shown, the upper and lower flanges 16f at both ends of the I-shaped cross member 14 in the vehicle width direction are arranged in the vehicle longitudinal direction, that is, in the same manner as in the second embodiment.
When the group of rivets 18 was enlarged in the same direction and the rivets 18 were widely distributed in the y direction as in the same example, the same torsion test was conducted. As a result, a result approximately similar to that of the second example was obtained. .

It should be noted that, instead of the cross member 14 having the I-shaped cross section shown in FIG. 5, the I-type formed by welding the upper and lower flanges 14f and the web 14w as shown in FIG. It was confirmed that the same effect as described above can be obtained even when the cross member 14 having a cross section is used.

Further, in the fourth embodiment of the present invention shown in FIGS. 7 and 8, an upper member 14u and a lower member 14l having a hat-shaped cross-section for most of the entire length except both ends in the vehicle width direction are provided. Are integrally connected by a large number of rivets 24, and the entire length excluding both ends has a closed cross-section structure.
An alligator type cross member 14 is used in which u and the lower portion 14l are expanded in a V shape and mounting flanges 14u 'and 14l' are formed at the respective tips. The cross member 14 has the mounting flanges 14u 'and 14l' fastened to the corresponding upper and lower flanges 16f of the gusset 16 by a plurality of rivets 18 (or four bolts in the figure). The gusset 16 has its web 16w fixed to the web 12w of the side rail 12 by a large number of rivets 20 (or bolts of the same effect).

The mounting flanges 14u 'and 14l', and the upper and lower flanges 16f of the gusset are in the vehicle width direction and the vehicle front-rear direction, that is, the x-direction and the y-direction, as compared with the case of the chassis frame having the conventional arigate type cross member. Both and / or at least one of them is enlarged. The ratio of the minimum value r _min and the maximum value r _max of the distance r _i from the equivalent center of gravity g of the four rivets 18 to the center line of each rivet is set within the range of 0.5 or more and 1 or less, as in the above-mentioned embodiments. (R _min / r _max = 0.95 in the case shown). Further, the separation distance x _{1 of the} rivet group 18 in the x direction and the separation distance y _{1 in the} y direction are
If at least one or both of the above is lg / 2, the distance from the center plane yO in the vehicle front-rear direction to the equivalent center of gravity g is 0.15lg
Above, that is, x ₁ ≧ 0.15lg or (and) y ₁ ≧ 0.15lg, and each rivet 18 has an average distance from the equivalent center of gravity g.
r _im is arranged so that it is sufficiently larger than the previous configuration.

Regarding the undercarriage frame 10 having the above structure and a conventional undercarriage frame having an alligator type cross member and rivet groups for fastening the cross member to the gusset are arranged in a range of r _min / r _max = 0.3 to 0.45 The same torsion test was carried out and the maximum shear stress in the rivet group and the durability times of the rivets and cross members were examined.
The results obtained are approximately the same as those shown in Fig. 11, and the maximum shear stress is effectively reduced by the rivet arrangement of this embodiment, the durability and reliability of the chassis frame are significantly improved from the conventional one, and the weight can be reduced. Was confirmed. The lower member 14l of the cross member is fixed only to both ends of the upper member 14u in the vehicle width direction to form a V-shaped joint portion. Therefore, the middle portion of the cross member 14 has an open cross-section upper member 14u.
Even in a cross member that is composed of only the above and has a relatively low torsional rigidity, by disposing the group of rivets 18 in the same manner as described above, substantially the same effect can be obtained for the reason substantially similar to each of the above embodiments. It was confirmed that

In each of the above-described embodiments, four rivets 18 (or bolts having substantially the same effect) for fastening the upper and lower flanges 14f of the cross member 14 to the corresponding upper and lower flanges 16f of the gusset 16 are arranged. But of course 5
One or more rivets or bolts can be used.

(Advantages of the Invention) As described above, a chassis frame of a truck 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 body front-rear direction, and is mounted inside the side rails. A gusset fixed to the side rail by a plurality of rivets or bolts, and a cross member extending in the vehicle width direction and having both ends fixed to the gusset by a plurality of rivets or bolts. , The distance from the equivalent center of gravity of the rivet or bolt group fastening the cross member to the gusset to the center line of each rivet or bolt is r _1, and the minimum value of r ₁ is r _min and the maximum value is r _min . when the _max, is the rivet or bolt arranged so as to satisfy _{0.5 ≦ r min / r max ≦} 1, further the distance from the vehicle center plane of the equivalent center of gravity and lg / 2, and the rivet Maximum distance in Kurumahaba direction of the bolt group
At least _one of x ₁ and the maximum longitudinal distance y _{1 in} the vehicle front-rear direction is set to 1.15 lg or more, and gussets are formed at both ends of the cross member due to twisting of the chassis frame generated while the truck is running. It is industrially advantageous because the maximum shear stress generated in the rivet or the bolt to be fastened can be effectively reduced, the durability and reliability of the chassis frame can be improved, and the weight reduction can be achieved.

[Brief description of drawings]

1 is a plan view showing a first embodiment of the present invention, FIG. 2 is a partial sectional view taken along the line II-II of FIG. 1 and viewed in the direction of the arrow, and FIG. 3 is a second embodiment of the present invention. Fig. 4 is a plan view showing an example, Fig. 4 is a plan view showing a third embodiment of the present invention, Fig. 5 is a cross-sectional view of the cross member 14 in Fig. 4, and Fig. 6 is a cross member of the third embodiment. FIG. 7 is a cross-sectional view showing a modified example, FIG. 7 is a plan view showing a fourth embodiment of the present invention, and FIG. 8 is a seventh VIII-VI.
Fig. 9 is a partial sectional view taken along line II in the direction of the arrow, Fig. 9 is a diagram for explaining the equivalent center of gravity of a plurality of rivets, and Fig. 10 is a plan view similar to Fig. 1 showing an example of a conventional chassis frame. , 11th
The figure shows the maximum shear stress occurring in the rivet group in the first embodiment and the number of times the rivet and the cross member are durable, in comparison with the maximum shear stress and the number of durability of the rivet group in the conventional chassis frame shown in FIG. FIG. 10 …… chassis frame, 12 …… side rails, 14 …… cross members, 16 …… gussets, 18 …… rivets.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Toshiharu Matsui 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Yoshiaki Tachibana 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Automobile Industry Co., Ltd. (72) Inventor Mikikazu Kobayashi 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Kunio Hara 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Kogyo Co., Ltd. (56) Bibliography Sho 63-1655 (JP, Y2)

Claims (1)

[Claims] 1. A pair of left and right side rails each having a groove-shaped cross section and extending in the front-rear direction of a vehicle body, and a gusset inserted inside the side rails and fixed to the side rails by a plurality of rivets or bolts. A rivet or bolt group for fastening the cross member to the gusset, the cross member having a cross member secured to the gusset by a plurality of rivets or bolts, the both ends extending in the vehicle width direction. Let r ₁ be the distance from the equivalent center of gravity to the center line of each rivet or bolt, and set the minimum value of r ₁ to r _1.
When r _min and the maximum value are r _max , the rivets or bolts are arranged so as to satisfy 0.5 ≦ r _min / r _max ≦ 1, and the distance of the equivalent center of gravity from the vehicle center plane is lg / 2. And at least _one of the maximum separation distance x _{1 in the} vehicle width direction of the rivet or bolt group and the maximum separation distance y _{1 in} the vehicle front-rear direction is set to 0.15 lg or more.