JPH02274671A - Under carriage frame for vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a chassis frame for a vehicle such as a truck.

(Terminology) In this specification, the term "equivalent center of gravity" has the following meaning in relation to a side rail that is fastened together by a plurality of rivets or bolts that connect both ends of the cross member in the vehicle width direction. be. That is, in FIG. 8 of the attached drawings, the side rails R, R2...Ro...Rn-1 are connected by an arbitrary number of rivets or bolts (n≧2).
, Rn are respectively G1. G2...Gi...
G, G, the cross-sectional area of each rivet or bolt -I
n Husband a1e R2...ai...'n-1"n, the coordinate vector of each rivet or bolt is rl + r2...
When ri...rn-1"n, the coordinate vector rg of the equivalent center of gravity I is expressed by the following equation. That is, rg positive, Gl air r 1/, no, GHa i (prior art) normal The truck consists of a pair of left and right side rails that have a groove-shaped cross-section and extend in the longitudinal direction of the vehicle body, and a plurality of cross members that are arranged in the vehicle width direction and have both ends fixed to the side rails. The vehicle is equipped with a chassis frame, and a front axle and a rear axle are attached to the chassis frame via respective suspension devices, and the cab, engine,
Loading platforms etc. are installed.

Inner stiffeners with a groove-shaped cross section that closely adhere to the inner surface of the side rails and extend in the longitudinal direction of the vehicle body are often installed in the side rails of parts such as the rear axle, which are subject to particularly large loads. It is fixed to the side rail with bolts. In addition, the above-mentioned cross member may appropriately include a member having a groove-shaped cross-section, a member having an IW shape, and a so-called alligator-type cross member in which a figure-7-shaped widening portion is formed at both end portions connected to the side rail. Both end portions of the cross members, which are adopted and placed in the high-load portions, are connected to the side rails by rivets or gels via the stiffeners.

(Problem to be Solved by the Invention) When a vehicle such as a truck is used under extremely harsh conditions, such as when a loaded vehicle is traveling at high speed on a rough road with severe unevenness, the undercarriage frame is subject to large torsions. When a load is applied, a large shear stress is generated in the side rail due to the rivets or bolts that fasten both ends of the cross member to the inner stiffener.

A typical configuration of a connecting portion between a cross member and an inner stiffener in a conventional chassis frame will be explained with reference to FIG. 9. In the figure, reference numeral 10 generally indicates the chassis frame, and the chassis frame The vehicle includes a pair of left and right side rails 12 that extend in the front-rear direction and have a groove-shaped cross section, and a cross member 14 that extends in the width direction of the vehicle and has a groove-shaped cross section. An inner stiffener 16 having a groove-shaped cross section is inserted into the side rail 12 so as to be in close contact with the inner surface of the side rail, and extends in the longitudinal direction of the vehicle body, and extends above the cross member 14. The ends of the flange and the lower 7 flange 14f in the vehicle width direction are connected to the corresponding upper 7 flange and the lower flange 16f of the inner stiffener 16 by four rivets or bolts 18 arranged in a cross-section in the illustration. The three rivets or bolts 18 that are fixed and arranged in the longitudinal direction of the vehicle body among the side rails 18 by the four rivets or bolts are collinear with the upper flange and the lower flange 12f of the side rail 12. ing.

In a normal chassis frame 10, each rivet 18 is
The distance to the center line of (or Pol 1) is expressed as ri, and r
The minimum value of r-, the maximum value 1
1 mi
When n is rmax, the value of rmin/'max is in the range of approximately 0.3 to 0.45, and in many cases, rivets or bolts of the same diameter and material are arranged. In the illustrated case, four rivets 18 or bolts are arranged in an L-shape, and the distance ri from the equivalent center of gravity g varies widely;
rrrlin/rmax is a low value of about 0.3 and ri
The average value of is also small.

As an example, cross member 1 made of a steel plate with a thickness of 6
4 and an inner stiffener 16 made of 8m thick steel plate.
are fastened together with four rivets 18 having a diameter of IQmR, and the flange 16f of the inner stiffener 16 other than the cross member connecting part is connected to the 7 flange 12f of the side rail 12 made of a steel plate with a thickness of 8 strips. diameter 10
mm, and the rivets 18 are arranged in an L-shape as shown in the figure.
FIG. 10 shows the results of a torsion test performed on the chassis frame arranged so that /r = 0.3. The above torsion test was carried out by fixing the rear portions of the left and right side rails 12 of the chassis frame, that is, the rear shirt shackle pin brackets (m) of the rear suspension springs, and fixing the rear shackle pin brackets (m) of the rear suspension springs to the rear shackle pin bracket mounting portions of the front suspension springs. Forces in opposite directions (one upward and the other downward) are applied to the undercarriage frame to repeatedly cause torsional displacement with a torsional angle of 4°, and the maximum shear stress δ (kl?) of the above rivet group is applied. /1111), as well as the number of repeated failures of the rivet (marked Q in the figure) and the number of repeated failures of the cross member (marked with M in the figure).

As is clear from the curve S indicating the maximum shear stress indicated by the dotted line in the same figure, in the conventional rivet arrangement shown in FIG. The number of rivet failure cycles N is extremely low, and the rivet or bolt may break early or the rivet or bolt may break due to long-term operation under extremely severe running conditions as mentioned above. It was confirmed that defects such as cracks were likely to occur in the adjacent plate materials of the cross member 14 and inner stiffener 16.

Further, when trying to prevent damage to the rivets or bolt group, or damage to the plates of the cross member 14 and inner stiffener 16 that cooperate with these rivets or bolts.

Conventionally, countermeasures such as adding multiple reinforcing plates and increasing the number of rivets or bolts used have been taken as needed in areas where strength is uncertain, but this is a waste of time. Furthermore, the vehicle has disadvantages such as an increase in vehicle weight, a decrease in effective load capacity, and deterioration in fuel efficiency.

The present invention provides an undercarriage frame in which both ends of a cross member are connected to the side rails by rivets or bolts via inner stiffeners, by reducing shear stress occurring in the rivets or bolts. The purpose is to improve the durability and reliability of the chassis frame and at the same time achieve weight reduction.

(Means for Solving the Problems) A vehicle chassis frame according to the present invention has been devised to achieve the above object, and has a groove-shaped cross section and a pair of left and right frames extending in the rear direction of the vehicle body. A side rail, an inner stiffener having a groove-shaped cross section that is inserted tightly inside the side rail and fixed to the side rail with a plurality of rivets or bolts, and is arranged to extend in the width direction of the vehicle. and a crossmen/J whose both ends are fixed to the inner stiffener with a plurality of rivets or bolts, each of which has an equivalent center of gravity of the group of rivets or bolts that fastens the crossmen/J to the inner stiffener. The distance to the center line of the rivet or bolt is ri, and the minimum value of ri is rmin.

When the maximum value is rmax, 0.5≦rmin/r
The rivet or bolt is arranged so as to satisfy max≦1.

(Function) According to the present invention, by arranging the plurality of rivets or bolts that fasten both ends of the cross member to the side rails via the inner stiffeners so that the difference in distance from the equivalent center of gravity is small as described above, As a result, the load due to the torsion of the undercarriage frame is carried evenly on each rivet or bolt (as compared to conventional arrangements), so that the maximum shear stress is correspondingly reduced.

(Example) Examples of the present invention will be specifically described below with reference to FIGS. 1 to 7. (Incidentally, the same reference numerals and parts are given to the members and parts that are substantially the same as or corresponding to the conventional structure explained with reference to FIG. 9, and redundant explanation will be omitted.) In the first embodiment of the present invention shown in FIGS. 1 and 2, a cross member 4 having a groove-shaped cross section has an upper flange and a lower flange 14f.
are fastened to the corresponding upper and lower flanges 16f of the groove-shaped inner stiffener 16 by four glue pets 18 (or equivalent bolts), and two of the rivets 18 are connected to the side rail 12. The flanges 12f are collinear. In addition, the inner stiffener 16 is attached to the side rail 12 by using a plurality of screw propellers 20 (or bolts with the same effect) to connect the upper 7 flange and the lower flange 16f to the parts other than the joint part with the cross member. Upper 7 langes and lower flange 12f
It has been concluded.

In the case of this embodiment, the distances ri from the equivalent center of gravity I of the 18 groups of rivets to the center line of each rivet are all equal, so the ratio of the minimum value rmin and the maximum value rmax of ri, rm
Each rivet is arranged so that i n/'max = ". Also, compared to the conventional configuration shown in FIG.
The dimension in the Y direction in the figure is formed to be considerably large, and two rivets 18 are arranged in this part, and as a result, the average distance rim from the equivalent center of gravity I to the center line of each rivet 18
(in this case, equidistant) is formed so that it is sufficiently large. The maximum separation distance y1 of the group of rivets 18 in the Y direction is the width y in the Y direction of the upper and lower flanges 14f of the cross member at the 1 position of the equivalent center of gravity.

is equal to or larger than 1/2 of y, "L 0
．． 5y.

is set to . In the figure, 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 J is indicated as tg/2. ) The undercarriage frame 10 having the above configuration was subjected to a torsion test under substantially the same conditions as the conventional undercarriage frame shown in FIG. When we investigated the durability, as shown by the dotted curve S in Figure 10, the maximum shear stress δ was approximately 12 kF! /mn, and the number of repeated failures N of the rivet 18 and cross member 14 is significantly increased compared to the conventional one.Therefore, safety under severe running conditions is significantly higher, and durability and reliability are effectively improved. It was confirmed that weight reduction could be achieved at the same time. In addition, in the above configuration, the rivet 1
8, rm i n/rmax = 0,
When similar tests were carried out by changing the values sequentially from 5 to 0.9, the results shown in Figure 10 were obtained for the maximum shear stress δ and the number of repeated failures N of the rivet 18 and cross member 14, respectively. It was also recognized that this was superior to the conventional chassis frame mentioned above.

Next, in the second embodiment of the present invention shown in FIGS. 3 and 4, two groove-shaped cross-section members are brought into contact with each other back to back at the web portion and are integrally connected by a rivet 22 or the like. A cross member 14 having a D-shaped cross section is used, and the Talos member has both end portions of the upper flange and lower flange 14f in the vehicle width direction extending long in the longitudinal direction of the vehicle body, that is, in the Y direction, just as in the first embodiment. A plurality of (four in the illustrated case) rivets 18 (or bolts with the same effect) are fastened to the upper and lower flanges 16f of the inner stiffener 16, and two of these rivets 18 are fastened to the upper and lower flanges 16f of the side rail 12. The lower flanges 12f are fastened and fixed together. Furthermore, the inner stiffener 16
, the upper flange and lower flange 16f are connected with a plurality of rivets 2 even in parts other than the joint with the cross member.
0 (or equivalent bolts) to the corresponding upper and lower flanks 12f of the side rail 12. The distances ri from the equivalent center of gravity g of the 18 groups of rivets to the center scarlet of each rivet are all equal, so rl
The ratio of the minimum value rmin n and the maximum value rmax rmin/
rmax is 1, and the maximum separation distance y1 of the same rivet group in the Y direction is equal to the width yo in the Y direction of the upper and lower seven flange 14f of the cross member 14 at the position of the equivalent center of gravity g, just as in the first embodiment. On the other hand, y, ≧o, sy
o.

It has the same configuration as the above-described vehicle chassis frame 10, but the rivet 18 is rmj n /rma! = 0.3~
A torsion test was conducted as described above on a conventional chassis frame arranged in the range of 0.45, and the rivet 1
When we investigated the maximum shear stress δ and the number of repeated failures of the rivet and cross member 4 in Group 8, we obtained results that were approximately similar to the maximum shear stress and the number of durability N shown in Figure 10, and furthermore, The arrangement of rivet 18 is rmXn/
The results were approximately the same when rmax was varied within the range of 0.5 to 0.9.

Incidentally, instead of the cross member 4 having a D-shaped cross section as shown in FIG. Even when using the holy section cross member 4,
It was confirmed that the same effects as above can be achieved.

Furthermore, in the third embodiment of the present invention shown in FIGS. 6 and 7, an upper member 14u and a lower member 144 each have a hat-shaped cross-sectional shape over most of their entire length, excluding both ends in the vehicle width direction. are integrally connected by a large number of rivets 24, and almost the entire length except for both ends has a closed cross-sectional structure, and at both ends, the upper member 14u and the lower part 14t are expanded into a figure 7 shape and are attached to the tip of the husband. An Alidata type cross member 14 is used which defines mounting flanges 14u' and 146'. The cross member 14 has the above-mentioned mounting flan 14u'
and 14t', a plurality (four in the illustrated case) of glue pets 18 ( In addition, the inner stiffener 16 connects the part other than the cross-menu N attachment part to the flange 12 of the side rail 12.
It is fixed to f by a plurality of rivets 20 (or equivalent I).

An upper flange and a lower flange 16 of the inner stiffener 16 that fasten the mounting flanges 14u' and 144'.
f is larger in the longitudinal direction of the vehicle body, that is, in the Y direction, as in each of the embodiments described above, than in the case of a conventional chassis frame equipped with an Alidata type cross member. The ratio between the minimum value 'min and the maximum value rmax of the distance from the equivalent center of gravity l of the four rivets 18 to the center line of each rivet is in the range of 0.5 or more and 1 or less, as in each of the above embodiments. (in the illustrated case, rIn, n/rmax=0.78). Further, the separation distance y1 of the group of rivets 18 in the Y direction is arranged such that y1≧o, syo with respect to the width y in the Y direction of the cross member 4 at the position of the equivalent center of gravity I, and The average distance rim of each rivet 18 from the equivalent center of gravity is sufficiently larger than in the previous configuration.

The chassis frame 10 having the above configuration and the rivet group that includes the Alidata type cross member and fastens the cross member to the inner stiffener are rm i n"rmax = 0.
The same torsion υ test as described above was conducted on a conventional chassis frame arranged in the range of 3 to 0.45, and the maximum shear stress in the rivet group, as well as the number of repeated failures of the rivet and cross member, were investigated. A result roughly approximated to that shown in FIG. 10 was obtained, and the rivet arrangement of this example effectively reduced the maximum shear stress, significantly improved the durability and reliability of the undercarriage frame compared to the conventional one, and also reduced the weight. It has been confirmed that you can get it. The lower member 14t of the cross member is fixed only to both end portions of the upper member 14u in the vehicle width direction to form a figure-7 joint, and therefore the middle portion of the cross member 14 is fixed only to the upper member 16u of the open cross section. It has been confirmed that the same effect can be achieved by arranging 18 groups of rivets in the same manner as described above even in a cross member having a relatively low torsional rigidity.

In each of the above embodiments, the upper and lower flanges 14f of the cross member 14 are fastened to the corresponding upper and lower flanges 16f of the inner stiffener 16.
8 (or substantially equivalent bolts), although it is of course possible to use five or more rivets or bolts.

(Effects of the Invention) As described above, the vehicle undercarriage frame according to the present invention has a pair of left and right side rails that have a groove-shaped cross-section and extend in the longitudinal direction of the vehicle body, and a pair of side rails that are in close contact with the inside of the same side rails. an inner stiffener having a groove-shaped cross-section and fixed to the side rail by a plurality of rivets or bolts;
A cross member is provided extending in the vehicle width direction and has both ends fixed to the inner stiffener with a plurality of rivets or bolts, and the cross member is fastened to the inner stiffener. The distance from the equivalent center of gravity of the rivet or bolt group to the center line of each rivet or yN silt is rl, and the same r.

When the minimum value of 1 is rmax and the maximum value of 1 is rmax, 0.
The above-mentioned rivets or bolts are arranged so as to satisfy 5≦1n rmin/rmax≦1, and both ends of the cross member are fastened to the inner stiffener by the torsion of the chassis frame that occurs while the truck is running. This has the advantage that the maximum shear stress occurring in the rivets or bolts can be effectively reduced, the durability and reliability of the chassis frame can be improved, and the weight can be reduced.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention, FIG. 2 is a partial sectional view taken along the line ■-■ in FIG. 1 in the direction of the arrow, and FIG. A plan view showing the embodiment, FIG. 4 is the third
A sectional view of the cross member 14 in the figure, FIG. 5 is a sectional view showing a modification of the cross member in the second embodiment,
Fig. 6 is a plan view showing a third embodiment of the present invention, Fig. 7 is a partial sectional view taken along the line ■-■ in Fig. 6 in the direction of the arrow, and Fig. 8 is the equivalent center of gravity of a plurality of rivets. Diagram explaining, No. 9
The figure is a plan view similar to Figure 1 showing an example of a conventional chassis frame, and Figure 10 shows the maximum shear stress occurring in the 18 groups of rivets in the first embodiment and the number of repeated failures of the rivets and cross member. FIG. 2 is a diagram illustrating the maximum shear stress and the number of repeated failures of the rivet group in the conventional undercarriage frame shown in the figure, and the comparison I-. 10... Chassis frame, 12... Side rail, 1
4...Cross member, 16...Inner stiffener,
18...Rivet. Fig. 1 Fig. 2 Off Fig. Fang 9 Fig. Fang 8 Fig. 10

Claims (1)

[Claims] A pair of left and right side rails that have a groove-shaped cross-section and extend in the front-rear direction of the vehicle body, and a groove-shaped cross-sectional shape that is inserted tightly inside the side rails and fixed to the side rails with multiple rivets or bolts. and a cross member extending in the vehicle width direction and having both ends fixed to the inner stiffener with a plurality of rivets or bolts, the cross member is attached to the inner stiffener. The distance from the equivalent center of gravity of the group of rivets or bolts fastened to the stiffener to the center line of each rivet or bolt is r_i, and the minimum value of r_i is r_m.
_i_n, when the maximum value is r_m_a_x, 0.5
A vehicle chassis frame, wherein the rivet or bolt is arranged so as to satisfy ≦r_m_i_n/r_m_a_x≦1.