JP2021004005A - Ladder frame for vehicle - Google Patents

Abstract

To reduce lateral bending stress that may occur in a specific part of a side member.SOLUTION: A ladder frame for a vehicle comprises: left and right side members 2; a cross member 6 coupling the left and right side members; and left and right reinforcement plates 11 extending from a position further forward than the cross member to a rearward position and respectively fixed to the left and right side members without being fixed to the cross member. The left and right side members respectively have laterally disposed flange portions 15H, and the left and right reinforcement plates each are superposed on and fixed to the respective flange portions. The left and right reinforcement plates respectively have, in longitudinal central portions thereof, projections 30 projecting toward inside in a vehicle width direction.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a rudder frame for a vehicle.

A ladder-shaped ladder frame is known as a frame used for vehicles such as trucks. The rudder frame includes left and right side members and a plurality of cross members connecting the left and right side members. Further, among the plurality of cross members, there is a center cross member that connects the left and right side members at a position between the front wheels and the rear wheels of the vehicle.

JP-A-2015-168270

According to the research results of the present inventor, it has been found that when the vehicle turns, a lateral bending stress that exceeds the permissible upper limit value is generated at a specific location of the side member near the joint portion of the center cross member. It is desirable to take some measures against such lateral bending stress to reduce the lateral bending stress.

Therefore, the present disclosure was devised in view of such circumstances, and an object thereof is to provide a rudder frame for a vehicle capable of reducing lateral bending stress generated at a specific position of a side member.

According to one aspect of the present disclosure
With the left and right side members,
A cross member that connects the left and right side members,
The left and right reinforcing plates extending from the position in front of the cross member to the position behind the cross member and fixed to the left and right side members without being fixed to the cross member.
With
The left and right side members have flange portions arranged sideways.
The left and right reinforcing plates are overlapped and fixed to the flange portion.
The left and right reinforcing plates are provided with a vehicle ladder frame characterized by having a projecting portion projecting inward in the vehicle width direction at a central portion in the longitudinal direction thereof.

Preferably, the cross member is a center cross member that connects the left and right side members at a position between the front wheels and the rear wheels of the vehicle, and the portion of the protruding portion on the front side of the center of the center cross member is rearward. It is formed longer than the side part.

Preferably, the protrusion has a shape that is asymmetrical with respect to the center of the center cross member.

Preferably, the protrusion has a trapezoidal shape that is asymmetrical in the front-rear direction.

Preferably, the vehicle rudder frame is configured to be applied to a rear two-axle vehicle.

According to the present disclosure, it is possible to reduce the lateral bending stress generated at a specific position of the side member.

It is a schematic plan view of the rudder frame for a vehicle which concerns on embodiment of this disclosure. It is an enlarged view of the part II of FIG. FIG. 3 is a sectional view taken along line III-III of FIG. FIG. 1 is a sectional view taken along line IV-IV of FIG. It is a VV cross-sectional view of FIG.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be noted that the present disclosure is not limited to the following embodiments.

FIG. 1 is a schematic plan view of a vehicle ladder frame according to the embodiment of the present disclosure. The vehicle to which the rudder frame 1 of the present embodiment is applied is a truck, and in particular, a relatively large rear two-axle truck. The rudder frame 1 of the present embodiment is configured to be applied to a rear two-axle vehicle. The front, rear, left, right, up and down directions of the vehicle are as shown in the figure. Reference numeral C1 indicates the center of the vehicle and the rudder frame 1 in the vehicle width direction.

The type and use of the vehicle are not particularly limited. For example, the vehicle may be a normal truck that is not a rear two-axle type or an SUV (Sport Utility Vehicle).

The rudder frame 1 includes left and right side members 2L and 2R, and a plurality of cross members connecting these side members 2L and 2R. There are four cross members in this embodiment. One is a front end cross member 3 that connects the front ends of the side members 2L and 2R. The other is a rear end cross member 4 that connects the rear ends of the side members 2L and 2R. The other is a trunnion cross member 5 to which a trunnion suspension (not shown) that supports the rear wheels 8 of the vehicle is attached. The other is a center cross member 6 arranged at a position between the front wheels 7 and the rear wheels 8. The center cross member 6 is arranged in front of the trunnion cross member 5 and behind the front end cross member 3. The front end cross member 3 is arranged at a position in front of the front wheel 7.

The rear wheel 8 includes a front rear wheel 8F and a rear rear wheel 8R. Two front rear wheels 8F and two rear rear wheels 8R are provided on each of the left and right sides. The front wheels 7 form steering wheels, one on each of the left and right wheels.

The trunnion cross member 5 is fixed to the left and right side members 2L and 2R via the left and right gusset plates 9L and 9R. That is, trapezoidal left and right gusset plates 9L and 9R are fixed to the left and right side members 2L and 2R, respectively, and both left and right ends of the trunnion cross member 5 are fixed to these gusset plates 9L and 9R.

The fixing of each fixing portion is performed by rivets (not shown). However, the fixing method is not limited to this, and other fixing methods (welding, bolting, etc.) may be adopted as an alternative or additionally. This point is the same at the fixed points described later.

The center cross member 6 has a relatively complicated shape as described later. The center cross member 6 is located at a position relatively distant from the front end cross member 3 and the front wheel 7. As a result, a relatively large opening 10 partitioned by these and the left and right side members 2L and 2R is formed between the center cross member 6 and the front end cross member 3. The center cross member 6 has a shape in which the inside in the vehicle width direction is narrowed from the outside in a plan view as shown.

In particular, in the present embodiment, the left and right reinforcing plates 11L and 11R are fixed at the fixed portion of the center cross member 6 on the left and right side members 2L and 2R and in the vicinity thereof, respectively, which is a feature of the present embodiment. .. Hereinafter, the left and right reinforcing plates 11L and 11R are collectively referred to as the reinforcing plate 11.

2 is an enlarged view of part II of FIG. 1, FIG. 3 is a sectional view taken along line III-III of FIG. 1, FIG. 4 is a sectional view taken along line IV-IV of FIG. 1, and FIG. 5 is a sectional view taken along line V-V of FIG.

Since the rudder frame 1 has a symmetrical configuration, only the configuration on the right side will be illustrated and described below, and the description on the left side will be omitted. Further, the right side member, the gusset plate and the reinforcing plate are basically collectively referred to by reference numerals 2, 9 and 11, respectively.

As shown in FIGS. 3 and 4, the side member 2 is formed of channel steel having a cross section that opens inward (left side) in the vehicle width direction. The side member 2 is a web that connects the upper and lower flange portions 15H and 15L arranged horizontally or horizontally and the outer (right side) edges of the flange portions 15H and 15L in the vehicle width direction arranged vertically or vertically. It has a portion 16 integrally.

The upper and lower corner reinforcing plates 17H and 17L are overlapped and fixed to the inner surface and the upper and lower corners of the side member 2, respectively. These corner reinforcing plates 17H and 17L have an L-shaped cross section, and extend forward and backward longer than the above-mentioned reinforcing plate 11.

As shown in FIGS. 2, 3 and 5, the center cross member 6 extends in the vehicle width direction and is fixed to the left and right side members 2 (2L, 2R) at both left and right ends thereof. Reference numeral C2 indicates a center cross member center C2 which is centered in the front-rear direction of the center cross member 6 and is orthogonal to the rudder frame center C1 (also shown in FIG. 1). The center cross member 6 of the present embodiment is formed by superimposing and fixing the upper center cross member 18H and the lower center cross member 18L to each other.

The upper center cross member 18H has a horizontal flat plate-shaped end 19. The upper center cross member 18H is fixed to the side member 2 by superimposing and fixing the end portion 19 on the lower surface of the lateral portion 20H of the upper corner reinforcing plate 17H. The upper center cross member 18H is gradually deformed so as to exhibit a hat-shaped cross-sectional shape from the end portion 19 toward the inside in the vehicle width direction. The upper end height H1 of the upper center cross member 18H in the vehicle width direction is only slightly higher than the upper end height H2 of the end portion 19, but the lower end height H3 is the end portion. The lower end height of 19 is made considerably lower than H4. (H1-H2) <(H4-H3).

As shown in FIGS. 2 and 5, the width of the upper center cross member 18H in the front-rear direction gradually decreases from the end 19 toward the inside in the vehicle width direction. The upper center cross member 18H is formed so as to be symmetrical with respect to the center cross member center C2.

The lower center cross member 18L exhibits a hat-shaped cross-sectional shape over the entire length in the vehicle width direction. The lower center cross member 18L is fixed to the side member 2 by superimposing and fixing the end portion 21 of the lower center cross member 18L in the vehicle width direction on the upper surface of the horizontal portion 20L of the lower corner reinforcing plate 17L. To The lower center cross member 18L is gradually inclined upward from the end portion 21 toward the inside in the vehicle width direction, and then becomes horizontal at the central portion 22. The horizontal central portion 22 is overlapped and fixed to the central portion 23 of the similarly horizontal upper center cross member 18H from below. At this time, as shown in FIG. 5, the upward convex portion 24 of the lower center cross member 18L is accommodated in the upward convex portion 25 of the upper center cross member 18H with a gap.

As shown in FIG. 5, the width of the lower center cross member 18L in the front-rear direction also gradually decreases from the end 21 toward the inside in the vehicle width direction. The lower center cross member 18L is also formed so as to be symmetrical with respect to the center cross member center C2.

As shown in FIGS. 2 to 4, the reinforcing plate 11 extends in the vehicle length direction, that is, in the front-rear direction from a position in front of the center cross member 6 to a position behind. The reinforcing plate 11 is overlapped and fixed on the flange portion of the side member 2, and specifically, the reinforcing plate 11 is overlapped and fixed on the upper surface of the upper flange portion 15H. However, the reinforcing plate 11 is not fixed to the center cross member 6. The reinforcing plate 11 has a protruding portion 30 projecting inward in the vehicle width direction at a central portion in the longitudinal direction thereof. The division line a in FIG. 2 indicates a boundary line between the main body portion 31 which is the base portion of the reinforcing plate 11 and the protruding portion 30. While the main body 31 is fixed to the upper flange portion 15H of the side member 2, the protruding portion 30 protrudes from the main body 31 in a non-contact state with the center cross member 6.

The main body 31 of the reinforcing plate 11 is formed in a rectangular shape having four corners chamfered long in the vehicle length direction. The width of the main body 31 in the vehicle width direction is substantially equal to the width of the upper flange portion 15H. However, the main body 31 is located slightly inside the upper flange portion 15H in the vehicle width direction, and the edge portion 34 inside the vehicle width direction of the main body 31 is slightly projected from the upper flange portion 15H inward in the vehicle width direction. ing. The main body 31 is positioned so as to be offset forward with respect to the center cross member center C2, and the length L1 from the center cross member center C2 to the front end 32 is from the length L2 from the center cross member center C2 to the rear end 33. Be lengthened.

The protruding portion 30 has a trapezoidal shape or a substantially trapezoidal shape that is long in the vehicle length direction in a plan view as shown in FIG. The lower base 35 of the protrusion 30 is connected to the main body 31 on the section line a, and the upper base 36 of the protrusion 30 is separated from the lower base 35 in parallel. The front legs 37 and the rear legs 38 of the protrusions 30 are tilted symmetrically in the front-rear direction. However, the inclination angle θ1 of the front leg 37 with respect to the rudder frame center C1 direction, that is, the front-rear direction is smaller than the inclination angle θ2 of the rear leg 38. The front leg 37 and the rear leg 38 are each smoothly curved so that the central portion is slightly recessed.

Of the protruding portions 30, the portion 30F on the front side of the center cross member center C2 is formed longer than the portion 30R on the rear side. The protruding portion 30 has a shape (specifically, a trapezoidal shape) that is asymmetrical with respect to the center cross member center C2. As a result, the length L3 from the center cross member center C2 to the front end 39 of the protrusion 30 is made longer than the length L4 from the center cross member center C2 to the rear end 40 of the protrusion 30. The front end 39 is the intersection of the lower base 35 and the front leg 37, and the rear end 40 is the intersection of the lower base 35 and the rear leg 38. The center cross member center C2 is located on the rear end of the upper base 36.

As shown in FIG. 3, the protruding portion 30 is positioned above the upper center cross member 18H, and is neither contacted nor fixed to the upper center cross member 18H.

As shown in FIG. 2, the rear end portion of the main body portion 31 overlaps with the front end portion of the right gusset plate 9R, whereby the rigidity in the front-rear direction is improved. The left and right gusset plates 9L and 9R are fixed to the lower surface of the upper flange portion 15H immediately after the upper corner reinforcing plate 17H.

As shown in FIGS. 3 to 5, another reinforcing plate 41 is also fixed to the lower surface of the lower flange portion 15L of the side member 2.

Next, the action and effect of this embodiment will be described. First, the problem of the ladder frame according to the comparative example without the reinforcing plate 11 will be described.

As shown in FIG. 1, for example, it is assumed that the vehicle turns to the left at an extremely low speed. Then, the vehicle tries to turn around the center position B of the eight rear wheels 8. The frictional force between the rear wheel 8 and the road surface acts as resistance to this turning. Therefore, a bending moment in the direction of arrow A centered on the center position B is added to the rudder frame. The center position B is located at the intersection of the trunnion cross member 5 and the rudder frame center C1.

At this time, according to the research results of the present inventor, it was found that a lateral bending stress higher than the allowable upper limit value is generated at a specific portion of the side member 2 near the joint portion of the center cross member 6.

Specifically, as shown by reference numeral P in FIGS. 1 and 2, an edge portion on the inner side in the vehicle width direction of the upper flange portion 15H of the side member 2 near the front end of the end portion 19 of the upper center cross member 18H ( It was found that in the so-called edge portion), high lateral bending stress as indicated by the arrow Q is concentratedly generated in the upper flange portion 15H.

Therefore, in the present embodiment, the reinforcing plate 11 is provided in order to reduce the lateral bending stress. According to the structure of the present embodiment, not only the bending rigidity of the upper flange portion 15H can be improved by providing the reinforcing plate 11, but also the protrusion 30 of the reinforcing plate 11 imparts tension facing the lateral bending stress Q. it can. Therefore, the bending rigidity of the upper flange portion 15H can be effectively improved with the minimum configuration. Then, the lateral bending stress Q generated at the specific portion P of the upper flange portion 15H can be reduced to the allowable upper limit value or less.

Further, the specific portion P is located in front of the center cross member center C2, and the protruding portion 30 is formed so that the portion 30F on the front side of the center cross member center C2 is longer than the portion 30R on the rear side. Has been done. The front portion 30F extends to the front of the specific portion P. As a result, the lateral bending stress Q generated at the specific location P can be dispersed, and the lateral bending stress Q at the specific location P can be suitably reduced.

Further, the protruding portion 30 has a shape that is asymmetrical with respect to the center C2 of the center cross member, and specifically, has a trapezoidal shape that is asymmetrical in the front-rear direction. As a result, the front-rear balance of the rigidity given to the upper flange portion 15H and thus the side member 2 after the addition of the reinforcing plate 11 can be optimized, and the side member 2 can be bent as evenly as possible when the vehicle turns.

That is, if the protruding portion 30 has a symmetrical shape in the front-rear direction, the bending rigidity of the rear portion of the center cross member center C2 is higher than the bending rigidity of the front portion in the configuration of the entire side member including the reinforcing plate 11 and the like. As a result of being too rigid and the rear side portion becoming difficult to bend, there is a risk that bending stress will be concentrated on the front side portion. According to the present embodiment, by making the protruding portion 30 asymmetrical in the front-rear direction, the bending rigidity of the rear side portion is intentionally lowered, and the bending rigidity of the front side portion is realized by that amount, and the front side portion is extremely bent. It can be suppressed. In the present embodiment, by adding the reinforcing plate 11, the cross-sectional coefficient of the side member 2 can be increased so as to be effective in the lateral bending direction, and the rigidity balance can be optimized.

Since the reinforcing plate 11 is not fixed to the center cross member 6, it is possible to suppress an excessive increase in the bending rigidity of the side member 2 due to the fixing, which is also advantageous for optimizing the rigidity balance and evenly bending the side member 2. is there.

For comparison, a reinforcing plate having only the main body 31 without the protruding portion 30 was also tested, but the lateral bending stress Q at the specific portion P could not be reduced to the allowable upper limit value or less. Therefore, it was confirmed that the reinforcing plate 11 of the present embodiment is advantageous.

Since the same reinforcing plate 11L is provided on the left side, the same effect can be obtained even when the vehicle turns to the right.

Although the embodiments of the present disclosure have been described in detail above, various other embodiments and modifications of the present disclosure can be considered.

(1) For example, a similar reinforcing plate 11 having a protruding portion 30 may be provided as an alternative or additionally to the lower flange portion 15L of the side member 2.

(2) The protruding portion 30 may have a front-rear asymmetric shape other than the trapezoidal shape, and may be, for example, a front-rear asymmetric rectangle whose front side portion is longer than the rear side portion.

(3) If necessary, the reinforcing plate according to the present disclosure may be applied to a joint portion of a cross member other than the center cross member, and is generated at a specific location of the side member when the vehicle is not turning. It may be configured to reduce the lateral bending stress.

The embodiments of the present disclosure are not limited to the above-described embodiments, and all modifications, applications, and equivalents included in the ideas of the present disclosure defined by the scope of claims are included in the present disclosure. Therefore, this disclosure should not be construed in a limited way and can be applied to any other technique that belongs within the scope of the ideas of this disclosure.

1 Ladder frame 2, 2L, 2R Side member 6 Center cross member 11, 11L, 11R Reinforcing plate 15H Upper flange part 30 Protruding part 30F Front part 30R Rear part C2 Center cross member center

Claims (5)

With the left and right side members,
A cross member that connects the left and right side members,
The left and right reinforcing plates extending from the position in front of the cross member to the position behind the cross member and fixed to the left and right side members without being fixed to the cross member.
With
The left and right side members have flange portions arranged sideways.
The left and right reinforcing plates are overlapped and fixed to the flange portion.
A rudder frame for a vehicle, wherein the left and right reinforcing plates have a protruding portion projecting inward in the vehicle width direction at a central portion in the longitudinal direction thereof. The cross member is a center cross member that connects the left and right side members at a position between the front wheels and the rear wheels of the vehicle.
The vehicle ladder frame according to claim 1, wherein a portion of the protruding portion on the front side of the center of the center cross member is formed longer than the portion on the rear side. The vehicle ladder frame according to claim 2, wherein the protruding portion has a shape that is asymmetrical with respect to the center of the center cross member. The vehicle ladder frame according to claim 3, wherein the protruding portion has a trapezoidal shape that is asymmetrical in the front-rear direction. The vehicle ladder frame according to any one of claims 2 to 4, which is configured to be applied to a rear two-axle vehicle.

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