JP2006027358A - Cab-back cross member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cab-back cross member capable of securing an in-the-cab surviving space by suppressing positively the forward movement of the cargo bed of a cab-over-engine truck at a head-on collision. <P>SOLUTION: The cab-back cross member 17 has a body 10 and two counter-sleeves 11, and is installed between the cab having a driver seat and the rear body 4 positioned behind the cab and attached to a chassis frame 2 provided extending under the cab and the rear body 4. The body 10 of the cab-back cross member has bottom parts 10a in two places to be coupled with the chassis frame 2. The counter-sleeves 11 are secured to parts near the two bottoms 10a of the body 10 of cab-back cross member, where the center of gravity of the whole cab-back cross member 17 is positioned below the center of gravity of the single body of the cross member body 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cab back cross member that is disposed between a cab and a loading platform and to which a chassis frame is attached.

  A cab supported by the front part of the chassis frame (hereinafter referred to as a cab) and a loading platform supported by the rear part of the chassis frame are provided, and the seating position of the driver in the cab is located generally in front of the engine. In a freight vehicle (hereinafter referred to as a cab overtrack), the kinetic energy at the time of a frontal collision with a rigid wall (hereinafter referred to as a barrier) is mainly due to the front end of a strong chassis frame striking the barrier and effectively deforming. Thus, a living space (hereinafter referred to as cab living space) is secured in the upper cab, and safety is maintained.

  A vertical joist extending in the vehicle front-rear direction is fixed to the bottom surface of the loading platform disposed behind the cab. The vertical joists are mounted on the upper surface of the chassis frame and fixed by U-bolts. Moreover, since there is a possibility that the fixing in the longitudinal direction of the vehicle body may be insufficient with only the U bolt, a loading platform stopper that spans the chassis frame and the vertical joist is provided. The loading platform stopper is fastened and fixed to the chassis frame and the vertical joist with bolts, and complements the fixing with the U bolts in the longitudinal direction of the vehicle body.

JP 2002-264838 A

  In the conventional structure described above, in order to secure a cab living space at the time of a frontal collision with the barrier, it is required to maintain the distance between the cab moving forward and the barrier surface as much as possible.

  However, the fixed strength of the loading platform with respect to the chassis frame is generally set assuming that a load of a predetermined weight is loaded on the loading platform, so that the loading load is loaded to the upper limit of the allowable weight on the loading platform. When a frontal collision occurs, it is difficult to completely suppress the forward movement of the loading platform.

  In order to eliminate such inconvenience, a cab back cross member that protrudes upward from the chassis frame is provided between the cab and the loading platform, and the loading platform that moves forward in the event of a collision is brought into contact with the cab back cross member, It is also possible to regulate the movement of the loading platform by the bending rigidity.

  However, in the structure where the lower end of the cab back cross member is simply connected to the chassis frame by fastening bolts, etc., the load at the time of collision tends to concentrate on the connection part (bolt etc.) between the cab back cross member and the chassis frame. The joint portion is easily damaged due to the shear failure of the bolt, and it is difficult to effectively prevent the movement of the cargo bed using the bending rigidity of the cab back cross member.

  Further, when the cab back cross member has two lower ends spaced apart in the vehicle width direction and these two lower ends are coupled to the chassis frame, the cab back cross member is in a cantilever state, and The weight of the upper part away from the chassis frame naturally increases. For this reason, the natural frequency that vibrates before and after the vehicle becomes a relatively low value, which may adversely affect the vehicle vibration characteristics.

  The present invention has been made in view of the above circumstances, and can effectively utilize energy absorption due to frame deformation for deceleration of the loading platform in the event of a frontal collision of a cab overtrack, and more reliably secure a cab living space. An object of the present invention is to provide a cab back cross member that can be used.

  In order to achieve the above object, the present invention provides a cab back cross member that is disposed between a cab having a driver's seat and a loading platform located behind the cab, and is attached to a chassis frame that extends below the cab and loading platform. The cab back cross member main body and at least two counter sleeves are provided.

  The cab back cross member main body has at least two lower ends coupled to the chassis frame. The two counter sleeves are respectively fixed in the vicinity of two lower ends of the cab back cross member main body, and the entire center of gravity of the cab back cross member is positioned below the single center of gravity of the cab back cross member main body.

  When the cab supported in front of the chassis frame collides with the barrier surface, the chassis frame decelerates, and the loading platform starts moving forward and hits against the cab back cross member and presses. Since the cab back cross member is located at the front lower side of the loading platform, the impact force from the loading platform acts on the upper portion of the cab back cross member main body. At the moment of the collision (the moment when the load from the loading platform is input to the cab back cross member), the impact force acts to translate the cab back cross member forward and at the same time cause rotation around the center of gravity. However, since the lower end portion of the cab back cross member main body is coupled to the chassis frame, the coupling portion between the cab back cross member main body and the chassis frame is an impact center (rotation center) for the translation and rotational motion of the cab back cross member. ), An excessive impact force acts on the joint portion, resulting in breakage or the like. Here, when the position where the impact force acts and the center of gravity are close to each other, it is difficult to bring the coupling portion and the center of impact close to each other.

  On the other hand, in the above configuration, the counter sleeve is fixed in the vicinity of the lower end of the cab back cross member main body, and the centroid of the cab back cross member is lower than the single centroid of the cab back cross member main body by the counter sleeve. Located in. Further, the center of gravity of the entire cab back cross member can be set to a desired position depending on the weight of the counter sleeve and the fixed position. Accordingly, the position where the impact force acts and the center of gravity can be set to a desired distance, the coupling portion and the impact center can be brought close to or coincide with each other, and the impact force acting on the coupling portion can be significantly reduced. Accordingly, it is possible to reliably prevent the joint portion between the cab back cross member and the chassis frame from being damaged, and to effectively prevent the movement of the cargo bed using the bending rigidity of the cab back cross member.

  Thus, according to the above configuration, the bending deformation of the cab back cross member main body and the frame deformation energy of the chassis frame can be effectively utilized for the deceleration of the loading platform, and the forward movement of the loading platform with respect to the cab is suppressed, And a cab living space can be ensured reliably.

  In addition, although the cab back cross member is in a cantilever state, the center of gravity of the entire cab back cross member can be positioned downward, so that the natural frequency that vibrates in the longitudinal direction of the vehicle becomes a relatively high value, and the vehicle vibration The influence on the characteristics can be suppressed to an extremely small level.

  Further, the chassis frame may include two frame members that are arranged at intervals in the vehicle width direction and extend along the vehicle front-rear direction. The cab back cross member main body is formed of a pipe-like member, and the two lower ends may be coupled to the two frame members, respectively, so that the two frame members may be connected.

  In the above configuration, since the frame members are connected by the cab back cross member main body, the rigidity of the frame member is improved. Further, since the cab back cross member main body is formed of a pipe-like member, the collision energy can be absorbed even by the deformation of the cab back cross member main body.

  Further, the counter sleeve may be disposed at a position where the cab back cross member main body interferes with the chassis frame when the cab back cross member main body is pressed forward by the loading platform and restricts the tilt of the cab back cross member main body downward in the front of the vehicle. Good. Thereby, a part of the load at the time of collision acts on the chassis frame via the counter sleeve, so that the concentration of the load on the coupling portion between the cab back cross member and the chassis frame is further eased. Therefore, it is possible to further reliably prevent the coupling portion between the cab back cross member and the chassis frame from being damaged, and to effectively prevent the movement of the cargo bed using the bending rigidity of the cab back cross member.

  According to the present invention, in the event of a frontal collision of a vehicle, it is possible to reliably prevent damage to the joint portion between the cab back cross member and the chassis frame, and to effectively use the deformation energy of the cab cross member for deceleration of the loading platform. Can do. Therefore, the forward movement of the loading platform with respect to the cab is suppressed, the cab is prevented from being crushed from the rear, and the cab living space can be reliably ensured.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a schematic side view of a cab overtrack according to the present embodiment, FIG. 2 is an enlarged view of a portion II in FIG. 1, FIG. 3 is a sectional view taken along line III-III in FIG. FIG. 5 is an enlarged view of a main part of FIG. 4, and FIG. 6 is a side view of FIG.

  As shown in FIG. 1, the cab overtrack 1 includes a chassis frame (frame member) 2 extending in the front-rear direction on both sides in the vehicle width direction, a cab 3 supported from below on a front portion of the chassis frame 2, and a chassis. And a loading platform 4 supported from below at the rear of the frame 2.

  The loading platform 4 includes a front iron plate 6 disposed in the vehicle width direction behind the cab 3 through an appropriate gap, and a tilt plate 7 extending opposite to the rear from both ends of the front iron plate 6 in the vehicle width direction, A rear gate 8 that connects the rear ends of the rear plate 7 at the rear of the vehicle body so as to be openable and closable; A vertical joist 5 that is fixed to the lower surface of the vehicle and extends in the front-rear direction on both sides in the vehicle width direction.

  As shown in FIG. 3, the vertical joists 5 are bent in opposite directions from the bottom wall 30, side walls 31, 32 extending opposite to each other upward from both ends of the bottom wall 30, and the upper ends of both side walls 31, 32. And has an inverted hat-shaped cross section with flanges 33 and 34 extending in the direction of the angle. Both flanges 33 and 34 are fixed to the lower surface of the bottom plate 9 of the loading platform 4, thereby forming a closed cross section between the vertical joists 5 and the bottom plate 9.

  The chassis frame 2 has a substantially rectangular shape including a bottom wall 20, side walls 21 and 22 that extend upward from both ends of the bottom wall 20, and an upper wall 23 that connects upper ends of both side walls 21 and 22. Has a closed cross section. The vertical joist 5 is placed on the chassis frame 2 with its bottom wall 30 in contact with the upper wall 23 of the chassis frame 2, and is connected and fixed on the chassis frame 2 by U bolts 40.

  As shown in FIGS. 2 and 3, bolt insertion holes 35 are respectively formed at the upper ends of the side walls 31 and 32 of the vertical joist 5. The U-bolt 40 is a side bar that is bent downward from both ends of the bottom bar portion 41 inserted into the bolt insertion hole 35 and the bottom bar portion 41 protruding outside the both side walls 31, 32 of the vertical joist 5. Parts 42 and 43. The distal ends of the side bar portions 42 and 43 are inserted into the fixing plate 44 and screwed into the nut 45. By tightening the nut 45, the vertical joist 5 is fastened and fixed to the chassis frame 2 between the fixing plate 44 and the bottom bar portion 41 of the U bolt 40. Further, as shown in FIG. 2, the vertical joist 5 and the chassis frame 2 are connected by a stopper member 46. The stopper member 46 is fastened and fixed to the vertical joists 5 and the chassis frame 2 by bolts 47 and nuts (not shown), respectively.

  As shown in FIGS. 4 to 6, the cab back cross member 17 has a cab back cross member main body 10 and two counter sleeves 11, and is arranged between the cab 3 (shown in FIG. 1) and the loading platform 4. The mounting frame 12 is coupled to the chassis frame 2.

  The cab back cross member main body 10 is composed of a pipe-like member bent in a substantially U shape, and the inner width between two opposite lower end portions (both end portions) 10a of the cab back cross member main body 10 is two. It is set approximately equal to the distance along the vehicle width direction of the outer surface of the chassis frame 2.

  The mounting bracket 12 has a substantially plate shape, and a concave portion along the outer surface shape of the cab back cross member main body 10 is bent and formed at an intermediate portion thereof. Bolt insertion holes (not shown) are respectively formed at predetermined positions on the side walls of the mounting bracket 12 and the chassis frame 2. The cab back cross member main body 10 has bolts 13 inserted into the bolt insertion holes of the mounting bracket 12 and the chassis frame 2 with the lower end portion 10a sandwiched between the recess of the mounting bracket 12 and the outer surface of the chassis frame 2. Then, the nuts 14 are screwed and tightened to the respective bolts 13 to be fastened and fixed to the chassis frame 2.

  The two counter sleeves 11 are respectively fixed near the upper portion of the lower end portion 10a of the cab back cross member main body 10 and approach the upper wall 23 (shown in FIG. 5) of the chassis frame 2. The counter sleeve 11 has a substantially cylindrical shape and has an inner diameter portion slightly larger than the outer diameter of the cab back cross member main body 10. Bolt insertion holes (not shown) for the sleeve fixing bolts 15 are formed in the peripheral wall of the counter sleeve 11. Above the lower end portion 10 a of the cab back cross member main body 10, a bolt hole (not shown) through which a sleeve fixing bolt 15 for fixing the counter sleeve 11 is inserted has a direction in which the cab back cross member main body 10 extends ( A plurality are formed along the vertical direction in the figure. By selecting one bolt hole from the plurality of bolt holes, the counter sleeve 11 can be fixed at a desired position of the cab back cross member main body 10. The counter sleeve 11 is inserted into the cab back cross member main body 10 in advance, and the sleeve fixing bolt 15 is passed through the bolt holes of the counter sleeve 11 and the cab back cross member main body 10 and is fixed by tightening the nut 16. .

  Next, an appropriate fixing position of the counter sleeve 11 with respect to the cab back cross member main body 10 will be described with reference to FIG. FIG. 7A is a schematic view of the cab back cross member 17 according to the present embodiment, and FIG. 7B does not have the counter sleeve 11 used for comparison with the cab back cross member 17 ( It is a schematic diagram of the cab back cross member 18 which consists only of the cab back cross member main body 10). In the figure, F is an impact force acting on the cab back cross members 17 and 18 from the load carrier 4, P is a load input point of the load carrier load on which the impact force F acts, G is the center of gravity of the entire cab back cross members 17 and 18, O Is the attachment point of the cab back cross members 17 and 18 (the position of the upper bolt of the bolts 13 shown in FIG. 5), ω is the rotational angular velocity, x is the distance between G and P, and h is the distance between G and O. Each is shown.

  When the cab over track 1 collides head-on with the barrier surface, the kinetic energy is absorbed mainly by effectively deforming the front end of the strong chassis frame 2. At that time, the forward movement of the loading platform 4 is suppressed by the U bolt 40 (shown in FIG. 1), the stopper member 46 (shown in FIG. 1), and the cab back cross member 17. At the moment when the load of the loading platform 4 is applied, an impact force F from the loading platform 4 acts on the cab back cross member 17.

  Since the cab back cross member 17 is located at the front lower side of the loading platform 4 (shown in FIG. 4), the loading platform load input point P at which the impact force F acts is as shown in FIG. 7A. Located at the top of 17. The impact force F acts to cause the cab back cross member 17 to translate forward and to rotate around the center of gravity G. However, since the cab back cross member 17 is coupled to the chassis frame 2 (shown in FIG. 5) by bolts 13 (shown in FIG. 5), the coupling portion (attachment point) between the cab back cross member 17 and the chassis frame 2 is attached. If O) is greatly deviated from the impact center (rotation center) with respect to the translational and rotational motion of the cab back cross member 17, an excessive impact force acts on the attachment point O, which may cause breakage or the like. Therefore, in order to reduce the impact force acting on the attachment point O, it is preferable that the attachment point O and the impact center are close to each other, and it is more preferable that the two coincide. That is, an appropriate fixing position of the counter sleeve 11 with respect to the cab back cross member main body 10 is a position where the center of impact is brought close to the attachment point O, and an optimal fixing position is a position where both coincide.

  Next, conditions for matching the impact center with the attachment point O will be described.

The relationship of the following equation (1) is established among the overall mass M of the cab back cross member 17 including the counter sleeve 11, the translational speed V _G of the center of gravity G, and the impact force F due to the load carrier inertial force.

M × V _G = F (1)
Moreover, the overall moment of inertia I _G of the cab back cross member 17 comprising a counter sleeve 11, and the rotational angular velocity omega, and the distance x between the bed load input point P and the center of gravity G, between the impact force F, the following The relationship of Formula (2) is materialized.

I _G × ω = x × F (2)
Furthermore, the translational velocity V _O of the attachment point O, and the translational speed V _G of the center of gravity G, the distance h between the center of gravity G and the mounting point O, between the rotation angular velocity ω, the relation of the following equation (3) To establish.

V _O = V _G −h × ω (3)
The following equation (4) is derived from the above equations (1) to (3).

V _O = F × (1 / M−h × x / I _G ) (4)
Here, when an impact center and the attachment point O coincides, for a V O _{= 0,} the following equation from the above equation (4) Relationship (5) is derived.

x = I _G / (M × h) (5)
Therefore, by setting the position of the center of gravity G so that the above formula (5) is established, the center of impact and the attachment point O can be matched, and based on this, an appropriate fixing position of the counter sleeve 11 is determined. Is done.

  Next, the cab back cross member 17 (shown in FIG. 7A) according to the present embodiment having the counter sleeve 11 and the cab back cross member 18 not having the counter sleeve 11 (shown in FIG. 7B). And will be described.

  As shown in FIG. 7B, in the case of the cab back cross member 18 without the counter sleeve 11, the position of the center of gravity G is determined depending on the cab back cross member main body 10, and the position can be freely set. Can not do it. Further, since the center of gravity G is located in the upper part close to the loading platform load input point P, the value of x is small and the value of h is large. As described above, when the center of gravity G is close to the loading platform load input point P, it is difficult to make the attachment point O and the impact center close to or coincide with each other based on the above formula (5). Impact force will act.

  On the other hand, in the case of the cab back cross member 17 of the present embodiment having the counter sleeve 11, the position of the center of gravity G is determined according to the weight and the fixed position of the counter sleeve 11, so that the weight and the fixed position are changed. By doing so, the position of the center of gravity G can be set freely. Further, since the center of gravity G is located away from the loading platform load input point P as compared with the case of FIG. 7B, the value of x is large and the value of h is small. For this reason, the attachment point O and the impact center can be brought close to or coincident with each other based on the above formula (5). Therefore, the impact force acting on the attachment point O can be remarkably reduced, the breakage of the connecting portion (bolt 13) between the cab back cross member 17 and the chassis frame 2 is surely prevented, and the cab back cross member main body 10 is The movement of the loading platform 4 can be effectively prevented using the bending rigidity.

  Further, as shown in FIG. 8, each counter sleeve 11 is close to the upper wall 23 of the chassis frame 2, so that when the cab back cross member body 10 is pressed forward by the loading platform 4, the chassis Interference with the upper wall 23 of the frame 2 prevents the cab back cross member main body 10 from tilting downward in the front of the vehicle.

  On the other hand, as shown in FIG. 9, in the cab back cross member 18 that does not have the counter sleeve 11, the load at the time of collision is concentrated on the connecting portion (bolt 13 or the like) between the cab back cross member 18 and the chassis frame 2. Therefore, it is difficult to effectively prevent the movement of the loading platform 4 using the bending rigidity of the cab back cross member 18.

  As described above, according to the present embodiment, a part of the load at the time of the collision acts on the chassis frame 2 via the counter sleeve 11, so that the load applied to the coupling portion between the cab back cross member 17 and the chassis frame 2. Concentration is further eased. Further, the deformation of the chassis frame 2 due to the load from the counter sleeve 11 also contributes to the absorption of impact energy. Therefore, it is possible to further reliably prevent the joint portion between the cab back cross member 17 and the chassis frame 2 from being damaged and to effectively prevent the movement of the loading platform 4 by using the bending rigidity of the cab back cross member 17.

  Although the cab back cross member 17 supported by the chassis frame 2 is in a cantilever state, the center of gravity of the cab back cross member 17 is located downward by providing the counter sleeve 11, so that the cab back cross member 17 vibrates in the longitudinal direction of the vehicle. Therefore, the natural frequency is relatively high, and the influence on the vehicle vibration characteristics can be suppressed to a very small value.

  Further, since the two chassis frames 2 that are arranged at intervals in the vehicle width direction and extend along the vehicle front-rear direction are connected by the cab back cross member 17, the rigidity of the chassis frame 2 is improved. Moreover, since the cab back cross member main body 10 is formed of a pipe-like member, the collision energy can be absorbed even when the cab back cross member main body 10 is crushed and deformed.

  As described above, according to the present embodiment, at the time of a frontal collision of the vehicle, the joint portion between the cab back cross member 17 and the chassis frame 2 is reliably prevented from being damaged, and the deformation energy of the cab back cross member 17 is reduced. Can be effectively utilized for the deceleration of the loading platform 4. Therefore, the forward movement of the loading platform 4 with respect to the cab 3 is suppressed, the cab 3 is prevented from being crushed from the rear, and the cab living space is reliably ensured.

  The counter sleeve 11 only needs to have a desired hardness and weight. For example, the counter sleeve 11 can be formed of metal, hard resin, or the like, but the material is not limited thereto.

It is a model side view of the cab overtrack of this embodiment. It is the II section enlarged view of FIG. It is the III-III sectional view taken on the line of FIG. It is a principal part perspective view of the cab overtrack provided with the cab back cross member. It is a principal part enlarged view of FIG. FIG. 5 is a side view of FIG. 4. It is a schematic diagram of a cab back cross member, (a) shows the case where it has a counter sleeve, (b) shows the case where it does not have a counter sleeve. FIG. 5 is a side view of a main part showing a state at the time of a collision of a cab overtrack provided with the cab back cross member of FIG. 4. It is a principal part side view which shows the state at the time of the collision of the cab overtrack provided with the cab back cross member which does not have a counter sleeve.

Explanation of symbols

1 Cab over track 2 Chassis frame (frame member)
3 Cab 4 Loading platform 5 Vertical joist 6 Standing iron plate 7 Trailing plate 8 Rear gate 9 Bottom plate 10 Cab back cross member body 11 Counter sleeve 12 Mounting bracket 13 Bolt 14 Nut 15 Sleeve fixing bolt 16 Nut 17 Cab back cross member 18 With counter sleeve No cab back cross member 20 Bottom wall 21, 22 Side wall 23 Top wall 30 Bottom wall 31, 32 Side wall 33, 34 Flange 35 Bolt insertion hole 40 U bolt 41 Bottom rod portion 42, 43 Side rod portion 44 Fixing plate 45 Nut 46 Stopper member

Claims (2)

A cab back cross member disposed between a cab having a driver's seat and a loading platform located behind the cab and attached to the cab and a chassis frame extending below the loading platform;
A cab back cross member body having at least two lower ends coupled to the chassis frame;
The cab back cross member main body is fixed in the vicinity of the two lower ends of the cab back cross member main body, and the entire center of gravity of the cab back cross member main body is positioned below the single center of gravity of the cab back cross member main body. A cab back cross member characterized by comprising a counter sleeve. The cab back cross member according to claim 1,
The chassis frame includes two frame members that are arranged at intervals in the vehicle width direction and extend along the vehicle front-rear direction.
The cab back cross member main body is formed of a pipe-shaped member, and the two lower end portions are coupled to the two frame members to connect the two frame members. Back cross member.

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