JPH02151581A - Under carriage frame for truck - Google Patents

Abstract

PURPOSE:To contrive the reduction of number of part items, simplification of structure, lightness of weight and the cost down or the like by using a member of groove type section with relatively large torsional rigidity only for a pair of front and rear cross members in a rear suspension mounting part. CONSTITUTION:In an under carriage frame, a pair of right and left side rails 12 are respectively connected to each other by many cross members 18 to 22. Here the paired front and rear intermediate cross members 22 are arranged in a rear suspension mounting location, and two or more gussets 26 of groove type sectional shape are respectively inserted in the side rail 12 in the vicinity of an end part of the intermediate cross member 22. And each gusset 26 secures to its each upper and lower flange 26f each upper and lower flange 22f of each intermediate cross member 22 by a rivet 32 or the like. While the two or more intermediate cross members 18, 22, arranged more in the front, are formed in an alligator type by respectively securing hat type sectional upper and lower members 18u, 20u.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an undercarriage frame for trucks, particularly trucks having a single rear axle supported by leaf springs.

(Prior Art) Most conventional trucks have a pair of left and right side rails each extending in the longitudinal direction of the vehicle body and each having a groove-shaped cross section, and side rails arranged at intervals in the longitudinal direction of the vehicle body and extending in the width direction of the vehicle body. The vehicle chassis frame includes a plurality of extending cross members, each of which has both ends secured to the side rails with bolts or rivets. For the above-mentioned cross member, members with a groove-shaped cross-section, members with a single-shaped cross-section, and so-called alligator-shaped members in which both end portions fixed to the side rails expand into a figure-7 shape are appropriately adopted. The ends of these cross members are often fixed to the upper and lower flanges of the side rails.

(Problem to be solved by the invention) In the case of trucks, depending on the conditions of the region in which they are operated, the conditions are extremely harsh, such as carrying cargo many times the set maximum load capacity and driving at high speeds on rough roads with many uneven surfaces. May be used below. Naturally, in this type of vehicle, the chassis frame undergoes extremely large bends in the vertical direction during operation.
Due to torsional and lateral bending loads, as well as their combined loads, there is a higher risk of cracks occurring in the undercarriage frame, especially the important side rails, compared to similar vehicles operating under normal conditions. . According to the research conducted by the present inventors, the above-mentioned damage to the chassis frame occurs at the top and bottom of the side rail.
This often occurs when the end of the cross member is fixed to the lunge and a member with a closed cross section with high torsional rigidity is used as the cross member.
It was observed that this phenomenon is likely to occur at the joints with other parts.

Conventionally, countermeasures have been taken to prevent damage to the chassis frame, particularly the side rails, such as attaching multiple reinforcing plates or L-shaped reinforcing materials to the damaged parts or dangerous parts where damage is feared. However, there were problems such as a complicated structure, an increase in the number of parts, an increase in manufacturing cost, and an increase in weight.

The present invention eliminates the drawbacks of the conventional chassis frame described above, has a simple structure, has a small number of parts, is lightweight, and is inexpensive.
Moreover, it is an object of the present invention to provide a new vehicle chassis frame that can effectively withstand high-speed driving on rough roads while being overloaded.

(Means for Solving the Problems) A truck chassis frame according to the present invention has been devised to achieve the above object, and has a pair of left and right cross sections extending in the longitudinal direction of the vehicle body, each of which has a groove-shaped cross section. A side rail and a plurality of cross members arranged at intervals in the longitudinal direction of the vehicle body and extending in the width direction of the vehicle, each having both ends attached to the side rail with bolts or rivets. Of the intermediate cross members excluding the cross members at the front and rear ends of the side rails, the intermediate cross members other than the rear suspension john attachment parts are alligator-shaped members with low torsional rigidity that have both ends fixed to the side rail webs. A set of front and rear cross members of the rear suspension mounting portion are inserted into the inner side of the side rail and fixed to the web, and have a groove-shaped cross section that also serves as a reinforcing plate for the suspension leaf spring bracket. The large size forming the set is formed from a groove-shaped member to which the upper and lower flanges are respectively fixed.

(Function) According to the present invention, among the intermediate cross members 9 excluding the cross members at the front and rear ends of the side rails, a pair of front and rear cross members disposed at the rear suspension joist mounting portions that bear most of the vehicle weight are included. The cross members are formed by open cross-section dovetail members having low torsional stiffness, and the ends of these cross members are connected to the webs of the side rails rather than to the 7 langes. By reducing the torsional rigidity of these cross members, the amount of force transmitted between them and the cross members that restrains the smooth deformation of the side rails is reduced, and the strength margin at the joint between the two is increased, which is effective. Damage will be avoided.

On the other hand, the front and rear cross members of the rear suspension mounting area, which bear most of the weight of the vehicle, are made of groove-shaped cross-section members that have relatively higher torsional rigidity than the other intermediate cross members mentioned above in order to withstand large loads. In the Talosmenpa, each of the upper and lower seven flange is fixed to the corresponding upper and lower flanges of the set. Further, the web of the large-sized set is fixed to the web of the adjacent side rail, and also serves as a reinforcing plate for the suspension leaf spring bracket. Place the upper and lower flanges of the groove-shaped cross members on the side rail at 7.
By fixing the large gusset to the upper and lower flanges of the large gusset instead of the lunges, and fixing the same large gusset to the web of the side rail, the side rail flange part, where relatively large stress is generated due to vertical bending load and torsional load, can be fixed. Breakage is effectively avoided, and the load transmitted from the rear suspension john is smoothly transmitted to the side rails and cross member.

(Example) Examples of the present invention will be specifically described below with reference to the accompanying drawings. The reference numeral 10 in the figure generally indicates a truck chassis frame, and the frame includes a pair of left and right side rails 12 extending in the longitudinal direction of the vehicle body and each having a groove-shaped cross section, and a pair of side rails 12 arranged at the front and rear ends of the side rails 12. It includes a leading end cross member 14, a trailing end cross member 16, and four intermediate cross members 18, 20, 22 and 24.

Among the intermediate cross members 18 to 24, the two rear cross members 22 and 24 are arranged at the rear suspension mounting position. 4, which is an enlarged side view of FIG. 3 and a sectional view taken along the IV-IV line and the V-V line of the same figure.
As shown in FIG.
Large gussets 26 and 28 having a groove-shaped cross section are inserted into the side rail 12 near the ends of the webs 26w and 24, respectively.
is fixed to the web 12w of the side rail 12 by bolts or rivets 30. In addition, the above gusset 2
The upper and lower flanges 22f and 24f of the K cross members 22 and 24 are fixed to each other by bolts or rivets 32, respectively. Further, on the outside of the side rail web 12w to which the gussets 26 and 28 are attached, there is a main spring front bracket 36 that pivotally supports the front end eye of the main leaf spring 34, which is shown by a dashed line in FIG. A main spring rear plastic bracket 40 that pivotally supports the rear end centerpiece via a shackle link 38, and a sub-spring front bracket 44 and a rear bracket 46 that support both ends of the sub-leaf spring 42 are attached, respectively. Platan) 36.44 and rear Platan) 40.4
6 is fixed to the side rail nib 12w and the gusset 26.
and 28 connect the cross members 22 and 24 to the side rail 1
2 as well as each of the above-mentioned brecs) 36, 44.

Side rail web 12 at 40 and 46 attachment parts
It also serves as a reinforcing member for w. Further, an axle housing 48 of the rear axle is attached to the main leaf spring 34 and the sub-leaf spring 42 using well-known fixing means such as U-bolts.

The intermediate cross members 8 and 2o disposed in front of the intermediate cross members 22 and 24 have substantially the same structure, and are viewed in the direction of the arrow in FIG. As shown in FIG. 7, each upper member 18u has a hat-shaped cross section.

20u, and a lower member 1st having the same hat-shaped cross section, which is fixed to the end of the upper member with a rivet or the like.

This is a so-called alidata type cross member composed of 20t. The upper members 18u, 20u and the lower member 18
The ends of t and 20/= each expand into a 7-shape as shown in the figure, and have upper 7 flange 18uf provided at the tip of each.
20uf and lower flange 18tf.

20tf are each fixed to the web 12w of the side rail 12 with bolts or rivets. These intermediate cross members i8 and 20 are members with an open cross section that opens downward, and are designed and layered to have relatively smaller torsional rigidity than the cross members 22 and 24 of the rear suspension mounting portion.

Finally, the cross members 14 and 16 at the front and rear ends are different from the intermediate cross members 18, 20, 22, and 24, and even if a crack or the like occurs at the joint with the side rail 12, the cross members 14 and 16 at the front and rear ends will be damaged by the chassis frame. 10 is not the main cause of serious accidents such as bending into a "〈" shape, so detailed illustrations and explanations of the structure will be omitted. As shown schematically, the front end cross member 14
is a member with a groove-shaped cross section, and its upper and lower seven flanges are fixed to the upper and lower flanges of the side rail 12 with bolts, rivets, etc. using an appropriate set as in the past, and the rear end The cross member 16 is also constituted by a member having a groove-shaped cross section, and its upper and lower seven flanges are bolted or riveted to the corresponding upper and lower flanges of the gusset, which has a groove-shaped cross section, similarly to the cross members 22 and 24. It is fixed by etc. Further, in FIGS. 1 and 2, reference numerals 50 and 52 indicate the side rail 1.
It is a reinforcing material with a normal L-shaped cross section inserted inside the 2, and serves to reinforce the mounting part of the front suspension (not shown) and the expanded part of the side rail.
Further, the center line labeled 54 is the center line of the front axle. Furthermore, in addition to the cross members 14 to 24 described above, brackets for engine mounts, brackets for supporting center bearings, etc. are installed between the left and right side rails 12. The illustration is omitted because the influence on the figure is small.

When a truck equipped with the chassis frame of the above configuration is overloaded and runs at high speed on a rough road, extremely large vertical bending loads, torsional loads, and lateral bending loads act on the chassis frame in combination. However, since the intermediate cross members 18 and 20 are formed of alligator-type members with low rigidity in the open cross section, the amount of force transmitted between the cross members 18 and 20 that restrains the smooth deformation of the side rail 12 is small. The side rail Also, the occurrence of defects such as cracks in the joints of the cross members is effectively prevented. In addition, a pair of cross members 22 and 24 at the front and rear of the rear suspension 4 suspension mounting area
is relative to the other intermediate cross member 18°20 in order to withstand the large load transmitted from the leaf springs 34 and 42 for rear wheel suspension via the side rail 12 and large gussets 26 and 28. It is made up of a member with a groove-shaped cross section that has high rigidity, and its upper and lower flanges have 22 pieces.

24f are secured to corresponding upper and lower flanges 26f and 28fK of large gussets 26 and 28, and these gussets 26 and 28 have their respective webs 26w and 28w secured to the adjacent web 12w of the side rail, and the leaf springs 34 and Since the spring bracket 36° supporting the spring bracket 42 also serves as a reinforcing member for the side rail at the mounting portion of the 44 and 40.46, the large load mentioned above is smoothly and effortlessly transmitted to the side rail 12, effectively reducing stress concentration side rail 1.
This prevents defects such as cracks from occurring at the joints between the cross members 2 and the cross members 22 and 24.

Furthermore, in the chassis frame 10 having the above configuration, the side rail 12 has a connecting member for the cross member and a side rail, compared to a conventional side rail in which reinforcing plates, L-shaped reinforcing members, etc. are attached in multiple layers. It has a simple structure in which large gussets 26 and 28 which also serve as reinforcing members are attached, and the number of parts is small, so it has the advantage of being able to reduce manufacturing costs and weight.

In the above embodiment, two intermediate cross members other than the part where the rear suspension is attached are arranged, but the number of intermediate cross members of the same type installed may vary depending on the dimensions of the chassis frame 10, especially the length in the longitudinal direction of the vehicle body. It will be increased or decreased as appropriate.

(Effects of the Invention) As shown diagonally above, the truck chassis frame according to the present invention has a pair of left and right side rails extending in the longitudinal direction of the vehicle body each having a groove-shaped cross section, and a spaced apart from each other in the longitudinal direction of the vehicle body. A cross member is provided with a plurality of cross members that extend in the width direction of the vehicle and are fixed at both ends to the side rail with bolts or rivets, excluding the cross members at the front and rear ends of the side rail. Among the intermediate cross members, the intermediate cross member other than the rear suspension mounting portion is formed of an alligator-shaped member with an open cross section and low torsional rigidity fixed to the web of the side rail at both ends, and is attached to the rear suspension. A pair of cross members at the front and rear of the mounting part are inserted into the inside of the side rail and fixed to the web, and a large set of upper and lower flanges with a groove-shaped cross section that also serves as a reinforcing plate for the suspension leaf spring bracket. The present invention is characterized in that the seven upper and lower lunges are formed from fixed groove-shaped members, and provides a low-cost chassis frame that is simple in structure, has a small number of parts, is lightweight, and has excellent durability and reliability. There are benefits to be gained.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view showing an embodiment of the chassis frame of the present invention, FIG. 2 is a side view of the chassis frame shown in FIG. 1, and FIG. 3 is an enlarged side view of the rear suspension layered portion of the chassis frame. Figure 4 is a sectional view taken along line ■-■ in Figure 3, Figure 5 is a sectional view taken along line V-V in Figure 3, and Figure 6 is a sectional view taken along line V-V in Figure 3.
The figure shows intermediate cross members 18 and 20 of the chassis frame.
FIG. 7 is an enlarged front view of the connecting portion between the side rail 12 and the side rail 12, and FIG. 7 is a cross-sectional view taken along the line ■-■ in FIG. 6 in the direction of the arrow. 10... Chassis frame; 12... Side rail;
18.20, 22 and 24... intermediate cross member; 2
6 and 28...gusset. O6 Fang 7

Claims (1)

[Claims] A pair of left and right side rails each extending in the longitudinal direction of the vehicle and each having a groove-shaped cross-section; Or, in a vehicle equipped with a plurality of cross members fixed by rivets, of the intermediate cross members excluding the cross members at the front and rear ends of the side rail, the intermediate cross members other than the rear suspension mounting portion have both ends attached to the side rail. It is formed by an alligator-shaped member with an open cross section and low torsional rigidity fixed to the web, and a pair of front and rear cross members of the rear suspension mounting portion are inserted inside the side rail and fixed to the web to provide suspension. This truck chassis frame is characterized in that the upper and lower flanges of the husband are fixed to the upper and lower flanges of a large gusset having a groove-shaped cross section that also serves as a reinforcing plate for a leaf spring bracket.