JP4362814B2 - Loading platform fixing structure - Google Patents

Description

  The present invention relates to a structure for fixing a cargo bed to a frame side member extending in the front-rear direction of a vehicle body.

  A cab (hereinafter, referred to as a cab) supported on a front portion of a frame side member (hereinafter referred to as a side member) and a loading platform supported on a rear portion of the side member, and a driver's seat in the cab In a freight vehicle (hereinafter referred to as a cab overtrack) whose position is generally in front of the engine, 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 side member. It absorbs by striking the barrier and effectively deforming, and thereby a living space (hereinafter referred to as a cab living space) is secured in the upper cab, and safety is maintained.

  A vertical joist extending along the side member 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 side member 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 straddles the side member and the vertical joist is provided. The loading platform stopper is fastened and fixed to the side member and the vertical joist with a bolt, and complements the fixing with the U bolt in the longitudinal direction of the vehicle body (see, for example, Patent Document 1).

JP 2002-264838 A

  In order to secure a living space for the cab during a frontal collision with the barrier of the cab overtrack, the distance between the moving carrier and the barrier surface should be maintained as much as possible so that the cab is not crushed by the carrier that moves forward. Is required.

  Here, the load acting between the side member and the loading platform side in the case of a frontal collision (total weight on the loading platform side x acceleration) is the same even in the same collision state (equal speed at the time of the collision) Depends on the total weight of the load on the loading platform. That is, the load is the smallest in an empty state where there is no load, and the load is greatest in a full load state where the load is loaded up to the upper limit of the loadable weight. Therefore, by setting the coupling strength between the vertical joists and the side members in accordance with the full loading state, it is possible to secure a living space while suppressing the forward movement of the loading platform.

  However, if the joint strength between the vertical joists and the side members is set on the basis of the full loading state, the amount of crushing deformation at the front end of the side member at the time of a frontal collision becomes excessive, and as a result, it becomes difficult to secure the cab living space.

  The present invention has been made in view of the above circumstances, and effectively suppresses the forward movement of the cargo bed at the time of a frontal collision regardless of the loading state of the cab overtrack, and even when the cargo bed movement occurs. The object of the present invention is to provide a loading platform fixing structure that can effectively absorb the kinetic energy of the loading platform and secure a cab living space.

In order to achieve the above object, the loading platform fixing structure according to the present invention includes a precompression spring unit. A vertical joist is fixed to the bottom of the loading platform. The precompression spring unit includes a spring, a spring case, a rear spring holder plate, and a spring shaft, and is disposed between the cargo bed and the frame side member. The spring case has a box shape, has an opening on the front surface thereof, and is fixed to the upper surface of the side member. The rear spring holder plate is accommodated in the spring case and is movable in the vehicle front-rear direction. The spring shaft has a front end portion fixed to the vertical joist and a rear end portion fixed to the rear spring holder plate, and extends in the vehicle front-rear direction while being inserted through the opening. The spring is accommodated between the front surface portion and the rear spring holder plate in a state where the spring is compressed in the vehicle front-rear direction so that the urging force in the extending direction acts on the front surface portion and the rear holder plate. When the vertical joist moves relative to the frame side member toward the front of the vehicle, a compressive force acts on the spring.

In the above configuration, when the cab supported in front of the frame side member collides with the barrier surface, the frame side member decelerates, and a load (inertial force) on the loading platform acts on the spring of the precompression spring unit.

  At this time, until the magnitude of the load acting on the spring reaches the biasing force of the spring potentially generated by the pre-compression (hereinafter referred to as the potential biasing force of the spring), the spring is compressed and elastically deformed. Instead, the relative movement of the frame side member in the forward direction on the loading platform side is prevented by the spring. Therefore, in such a state, the kinetic energy on the loading platform side is absorbed mainly by the crushing deformation of the front end of the frame side member.

  When the magnitude of the load acting on the spring exceeds the potential biasing force of the spring, the forward movement of the loading platform side relative to the frame side member starts, and the spring is compressed and elastically deformed. Therefore, in this state, the kinetic energy on the loading platform side is absorbed mainly by the crushing deformation of the front end of the frame side member and the elastic deformation of the spring.

  For example, when the loaded weight is small as in an empty state and the load generated at the time of collision is smaller than the potential biasing force of the spring, the relative movement of the frame side member to the front of the loading platform side is prevented by the spring, and the frame is mainly used. The kinetic energy on the loading platform side can be absorbed by the crushing deformation of the front end of the side member.

  On the other hand, when the load weight is large and the load generated at the time of collision is larger than the potential biasing force of the spring as in the full loading state, the movement of the loading platform side is prevented by the spring immediately after the collision, and then the loading platform side The movement starts, the spring is compressed and elastically deformed, and the kinetic energy on the loading platform side can be absorbed mainly by the crushing deformation of the front end of the frame side member and the elastic deformation of the spring.

  In this way, regardless of the loading state of the cab overtrack, the forward movement of the loading platform at the time of a frontal collision is effectively suppressed, and even when the loading platform movement occurs, the kinetic energy on the loading platform side is reduced by the compression elastic deformation of the spring. It can be absorbed effectively, and a cab living space can be secured.

  Also, by changing the spring constant and pre-compression amount of the pre-compression spring unit, the magnitude of the load at the start of movement on the loading platform side, the amount of kinetic energy that can be absorbed by the elastic deformation of the spring after the start of movement, etc. Load characteristics can be set freely. Therefore, it is possible to efficiently absorb energy by providing a precompression spring unit having optimum characteristics for a cab overtrack having a different vehicle body structure and loadable weight.

  In the structure where the vertical joist is fixed to the lower part of the loading platform and the vertical joist is connected to the frame side member by the U bolt, when the loading platform side moves relative to the frame side member toward the front of the vehicle, the U bolt tilts toward the front of the vehicle. To do. For this reason, the U-bolt on the loading platform side and the pre-compression spring unit may be coupled by a coupling member so that a compression force acts on the spring by the tilting of the U-bolt toward the front of the vehicle.

  In the said structure, a precompression spring unit can be functioned using the U volt | bolt generally used for the fixing structure of a loading platform.

  The spring of the precompression spring unit may be a hollow spring formed of a tubular body.

  In the above configuration, after the hollow spring is compressed and elastically deformed by the movement of the loading platform side, when the loading platform side further moves, the hollow spring itself, which is a tubular body, is crushed and plastically deformed to absorb the kinetic energy on the loading platform side. Therefore, the amount of kinetic energy that can be absorbed is increased, and the cab living space can be secured more satisfactorily.

  Further, the amount of kinetic energy that can be absorbed by plastic deformation can be freely set by changing the tube thickness or material of the hollow spring. Accordingly, it is possible to provide more efficient energy absorption by providing a precompression spring unit having optimum characteristics for a cab overtrack having a different vehicle body structure and loadable weight.

  The precompression spring unit may be provided with a spring shaft that compresses the spring by moving forward of the vehicle, and the spring shaft may be connected to the loading platform side.

  In the above configuration, since the kinetic energy can be absorbed by the deformation of the spring shaft after the deformation of the spring is completed, the amount of kinetic energy that can be absorbed further increases.

  As described above, according to the present invention, regardless of the loading state of the cab overtrack, the forward movement of the loading platform at the time of a frontal collision is effectively suppressed, and even if the loading platform movement occurs, the kinetic energy of the loading platform has been reduced. Can be effectively absorbed, and the amount of movement of the carrier can be kept small, and a cab living space can be secured.

  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 perspective view schematically showing the main part of the present embodiment, and FIG. 4 is a precompression spring unit. FIG. 5 is a sectional view of a hollow spring, FIG. 6 is a schematic side view of a cab overtrack at the time of a frontal collision, and FIG. 7 is a side view schematically showing the inside of a precompression spring unit. (B) represents the time of elastic deformation, and (c) represents the time of plastic deformation. The arrow FR in the figure indicates the front of the vehicle. The front-rear direction is the front-rear direction of the vehicle unless otherwise specified.

  As shown in FIG. 1, the cab overtrack 1 is supported from below by a chassis frame side member (hereinafter referred to as a side member) 3 that extends in the front-rear direction on both sides in the vehicle width direction, and a front portion of the side member 3. A cab 5 (hereinafter referred to as a cab) 5 and a loading platform 7 supported on the rear part of the side member 3 from below.

  The loading platform 7 includes a front iron plate 9 disposed in the vehicle width direction behind the cab 5 with an appropriate gap, and a side plate 11 extending oppositely from both ends of the front iron plate 9 in the vehicle width direction. A rear gate 13 that connects the rear ends of the rear plate 11 at the rear of the vehicle body so as to be openable and closable; and a bottom plate 15 that forms a bottom surface of a rectangular housing space defined by the front iron plate 9, the upper plate 11, and the rear gate 13. ing. A vertical joist 17 extending in the front-rear direction on both sides in the vehicle width direction is fixed to the lower surface of the bottom plate 15.

  As shown in FIG. 3, the vertical joists 17 are bent in opposite directions from the bottom wall 19, side walls 21, 23 extending opposite to each other upward from both ends of the bottom wall 19, and upper ends of both side walls 21, 23. And an inverted hat-shaped cross section having flanges 25 and 27 extending in the direction. Both flanges 25 and 27 are fixed to the lower surface of the bottom plate 15 of the loading platform 7, thereby forming a closed cross section between the vertical joists 17 and the bottom plate 15.

  The side member 3 has a substantially U-shaped cross section including a side wall 29 and an upper wall 31 and a lower wall 33 that extend from the upper and lower ends of the side wall 29 so as to face each other in the vehicle width direction. The vertical joists 17 are placed on the side members 3 with their bottom walls 19 in contact with the upper walls 31 of the side members 3, and are connected and fixed on the side members 3 by U bolts 37. The side members 3 on both sides in the vehicle width direction are connected by chassis frame cross members (hereinafter referred to as cross members) 35.

  As shown in FIGS. 2 and 3, bolt insertion holes 41 are respectively formed at the upper ends of both side walls 21 and 23 of the vertical joist 17. The U-bolt 37 includes side bar portions 45 and 47 that are bent downward from both ends of the bottom bar portion 43 inserted into the hole 41 and the bottom bar portion 43 projecting outside the both side walls 21 and 23 of the vertical joists 17. And. The distal ends of the side bar portions 45 and 47 are inserted through the fixing plate 49 and screwed into the nut 51. By tightening the nut 51, the vertical joist 17 is fastened and fixed to the side member 3 between the fixing plate 49 and the bottom bar portion 43 of the U bolt 37.

  As shown in FIG. 3, a precompression spring unit 71 is fixed to the side member 3. As shown in FIGS. 4 and 7A, the precompression spring unit 71 includes a coiled hollow spring 73, a substantially rectangular box-shaped spring case 75, a front spring holder plate 77, and a rear spring holder plate. 79, a spring shaft 81, front and rear spring holding nuts 83 and 85, and a connecting nut 87.

  The spring case 75 has two openings 75a and 75b and two side openings 75c that are opposed to each other. The hollow spring 73, the front spring holder plate 77, the rear spring holder plate 79, and the spring shaft 81 are accommodated in the spring case 75 from the side opening 75c. The front spring holder plate 77 is disposed so as to close the front opening 75a from the inside, and the rear spring holder plate 79 is disposed so as to close the rear opening 75b from the inside. The frame-shaped portions that define the front and rear openings 75a and 75b abut against the front and rear spring holder plates 77 and 79, respectively, and both spring holder plates 77 and 79 define the front and rear openings 75a and 75b. The movement to the outside of the spring case 75 is prevented. The distance between the inner surfaces of the spring holder plates 77 and 79 in a state where the front and rear spring holder plates 77 and 79 are in contact with the frame portions of the front and rear openings 75a and 75b, respectively. It becomes the front and back length.

  The natural length of the hollow spring 73 is set to be longer than the longitudinal length inside the spring case 75 (hereinafter referred to as the spring case length), and is accommodated between the spring holder plates 77 and 79 in a pre-compressed state. . Shaft insertion holes 77a and 79a are formed in the spring holder plates 77 and 79, respectively.

  The front end portion 81a and the rear end portion 81b of the spring shaft 81 are respectively formed with screw portions. The spring shaft 81 passes between the shaft insertion holes 77 a and 79 a through the coil inner diameter portion of the hollow spring 73 in a state where the hollow spring 73 and the spring holder plates 77 and 79 are accommodated in the spring case 75. In this state, spring holding nuts 83 and 85 are screwed into the front end portion 81a and the rear end portion 81b of the spring shaft 81 protruding from the spring holder plates 77 and 79, respectively.

  In the pre-compression spring unit 71 assembled as described above, the hollow spring 73 is compressed so that an urging force in the extending direction acts, and both spring holder plates 77 and 79 are moved toward the outside of the spring case 75. Always pressing.

  As shown in FIG. 5, the hollow spring 73 is formed in a coil shape by a tubular body (for example, a metal tube) having a hollow portion 73a therein.

  As shown in FIG. 3, fixed flange portions 89 and 91 extending in the front-rear direction are formed on the front and rear edges of the side opening 75 c of the spring case 75. The fixing flange portions 89 and 91 are fastened and fixed to the side wall 29 in a state of being in surface contact with the inner surface of the side wall 29 of the side member 3. Accordingly, the precompression spring unit 71 is fixed to the side member 3, and the side opening 75 c of the spring case 75 is closed by the side wall 29 of the side member 3 in this state. That is, the periphery of the hollow spring 73 is covered with the spring case 75 and the side wall 29, and the hollow spring 73 is restricted so as to be deformed only in the axial direction.

  The precompression spring unit 71 is arranged behind the U-bolt 37 in the vehicle. In the present embodiment, the cross member 35 disposed behind the U bolt 37 is disposed further rearward.

  The front end portion 81a of the spring shaft 81 protruding from the spring holder plates 77 and 79 to the outside of the spring case 75 and the bottom bar portion 43 of the U bolt 37 are connected by a wire 93 as a connecting member. A connecting nut 87 is screwed to the front side (outside) of the spring holding nut 83 at the front end portion 81 a of the spring shaft 81, and one end of the wire 93 is connected to the spring shaft 81 between the spring holding nut 83 and the connecting nut 87. It is wound and held between both nuts 83 and 87. The other end of the wire 93 is housed and fixed in a groove (not shown) formed in the bottom bar portion 43.

  When a force for moving the frame side member 3 relative to the front of the vehicle acts on the vertical joist 17 (loading platform 7 side), the U-bolt 37 tilts toward the front of the vehicle, and the rod bottom portion 43 tends to move toward the front of the vehicle. As a result, a tensile force acting forward of the vehicle acts on the spring shaft 81 via the wire 93, and a compressive force acts on the hollow spring 73.

  The end of the cross member 35 has a notch 35a that allows movement of the spring shaft 81 and a wire insertion hole (not shown) that allows insertion and movement of the wire 93 on the upper wall 31 of the side member 3. Wire insertion holes (not shown) that allow insertion and movement of the wires 93 are formed.

  Next, regarding the operation of the present embodiment, the fixing structure of the present embodiment by the pre-compression spring unit 71 and the general fixing structure by the loading platform stopper member 53 (shown by a two-dot chain line in FIGS. 1 and 2) are compared. To explain.

  The loading platform stopper member 53 is disposed on the vertical joists 17 and the side walls 21 and 29 on the outer side of the side members 3 so that the upper end of the loading platform stopper member 53 is inclined forward of the vehicle body. Bolt insertion holes (not shown) are formed at predetermined positions of the vertical joists 17 and the side walls 21 and 29 outside the side members 3, and welds corresponding to the bolt insertion holes are formed on the inner surfaces of the side walls 21 and 29. A nut (not shown) is welded. A bolt insertion hole (not shown) having an inner diameter substantially equal to or slightly larger than the outer diameter of the threaded portion of the bolt 61 is formed in the lower portion 57 of the loading platform stopper member 53. The upper portion 59 of the platform stopper member 53 has a long hole shape having a width substantially equal to or slightly larger than the outer diameter of the threaded portion of the bolt 65 and extending in substantially the same direction as the tilt direction of the platform stopper member 53. Bolt insertion holes 67 are formed. The upper portion 59 and the lower portion 57 of the loading platform stopper member 53 are fastened to the vertical joists 17 and the side walls 21 and 29 of the side members 3 by bolts 65 and 61 that are inserted into the bolt insertion holes 67 and 63 and screwed into the weld nuts, respectively. And fixed. Since the upper bolt insertion hole 67 has a long hole shape, when the side member 3 and the vertical joist 17 are assembled, the relative positions of the bolt insertion hole and the weld nut are shifted from the design positions between the side walls 21 and 29. So-called assembly errors are absorbed.

  First, the case of the fixing structure of this embodiment will be described.

  As shown in FIG. 6, when the cab 5 collides head-on with the barrier surface 95, the side member 3 starts to decelerate. And while the front-end part of the side member 3 is crushed, the load (inertial force) by the side of the loading platform 7 acts as a tensile force on the hollow spring 73 of the precompression spring unit 71 via the U bolt 37 and the wire 93.

  At this time, until the magnitude of the load acting on the hollow spring 73 reaches the urging force of the hollow spring 73 that is potentially generated by pre-compression (hereinafter, referred to as the latent urging force of the hollow spring 73), As shown in FIG. 7A, the hollow spring 73 maintains its initial state without undergoing compressive elastic deformation, and the hollow spring 73 prevents the vertical joist 17 (loading platform 7 side) from moving forward relative to the side member 3. Is done. Therefore, in this state, the kinetic energy on the loading platform 3 side is absorbed mainly by the crushing deformation of the front end of the side member 3. The potential biasing force of the hollow spring 73 can be obtained from the spring constant k × pre-compression amount x of the hollow spring 73.

  When the magnitude of the load acting on the hollow spring 73 exceeds the potential biasing force of the hollow spring 73, the relative movement of the side member 3 toward the front of the loading platform 7 starts, and as shown in FIG. The shaft 81 is pulled forward, and the hollow spring 73 is compressed and elastically deformed. At this time, as indicated by a region A in FIG. 8, the displacement on the loading platform 7 side (the displacement of the spring shaft 81) increases substantially linearly as the load increases. Accordingly, in such a state, the kinetic energy on the loading platform 7 side is absorbed mainly by the crushing deformation of the front end of the side member 3 and the elastic deformation of the hollow spring 73. In addition, if it exists in this elastic deformation area | region, after a load is removed, the hollow spring 73 will return to an initial state, and the loading platform 7 will return to an original state.

  After the hollow spring 73 is compressed and elastically deformed, when the loading platform 7 side further moves, as shown in FIG. 7C, the hollow spring 73 itself, which is a tubular body, is crushed and plastically deformed, and the kinetic energy on the loading platform 7 side. To further absorb. At this time, as indicated by a region B in FIG. 8, the displacement on the loading platform 7 side (displacement of the spring shaft 81) increases as the load increases. Therefore, the kinetic energy that can be absorbed is increased, and the cab living space can be further ensured.

  If the load carrier 7 side further moves after the hollow spring 73 is plastically deformed, the spring shaft 81 is deformed, and finally the precompression spring unit 71 is broken due to breakage or the like. As shown in the region C of FIG. 8, the deformation behavior of the spring shaft 81 is such that the displacement on the loading platform 7 side increases almost linearly as the load increases in the initial stage, and finally breaks (the breaking point is Indicated in FIG. 8 by D). Therefore, the kinetic energy that can be absorbed is further increased, and the cab living space can be further ensured.

  Thus, according to the precompression spring unit 71 of the present embodiment, for example, when the load weight is small as in an empty state and the load generated at the time of collision is smaller than the potential biasing force of the hollow spring 73, the side member 3 is prevented by the hollow spring 73, and the kinetic energy on the loading platform 7 side can be absorbed mainly by the crushing deformation of the front end of the side member 3.

  On the contrary, when the load weight is large as in the full load state and the load generated at the time of collision is larger than the potential biasing force of the hollow spring 73, the movement on the loading platform 7 side is prevented by the hollow spring 73 immediately after the collision, Thereafter, movement on the loading platform 7 side starts. Then, according to the magnitude of the load, the side member progresses in a stepwise manner from the deformation of the spring shaft 81 to the break through the elastic deformation of the compressed hollow spring 73 to the plastic deformation of the hollow spring 73 being crushed. 3, and the deformation of the precompression spring unit 71 including the hollow spring 73 and the spring shaft 81 can sufficiently absorb the kinetic energy on the loading platform 7 side.

  On the other hand, in the fixed structure using the rigid body connection using the platform stopper member 53, when a forward load is applied from the platform 7 side to the platform stopper member 53 due to a collision, the bolt 65 first has a bolt insertion hole 67 having a long hole shape. A so-called shift occurs in the relative movement (region P in FIG. 9). Then, the loading platform stopper member 53 expands and deforms (region Q in FIG. 9), and finally the loading platform stopper 53 breaks (the breaking point is indicated by R in FIG. 9). Therefore, the amount of kinetic energy that can be absorbed by the platform stopper member 53 is smaller than that of the pre-compression spring unit 71 of the present embodiment, and when the loaded weight is large and the load generated at the time of the collision is large as in the fully loaded state, the collision There is a possibility that the loading platform 7 side may move forward at an early stage, which is disadvantageous for securing the cab living space. In such a rigid body connection, once the displacement occurs on the loading platform 7 side, the initial state is not restored.

  As described above, according to the present embodiment using the elastic connection, the amount of energy absorption can be remarkably increased as compared with the rigid body connection using the cargo bed stopper member 53, and an appropriate energy can be obtained according to the loaded weight. Absorption can be performed. Accordingly, regardless of the loading state of the cab overtrack 1, the forward movement of the loading platform 7 side at the time of a frontal collision is effectively suppressed, and even if the loading platform 7 moves, the deformation of the hollow spring 73 causes the loading platform 7 side. Thus, the amount of movement on the loading platform 7 side can be kept small, and the cab living space can be secured.

  Further, by changing the spring constant, pre-compression amount, etc. of the hollow spring 73 of the pre-compression spring unit 71, the magnitude of the load at the start of movement on the loading platform side and the kinetic energy that can be absorbed by the elastic deformation of the spring after the start of movement. Load characteristics such as quantity can be set freely. The spring constant can be changed by changing the diameter of the material of the hollow spring 73 or the winding diameter or tube thickness when the coil is wound into a coil shape, and the precompression amount is changed by changing the spring natural length or the spring case length. be able to. Furthermore, by changing the tube thickness or material of the hollow spring 73, the amount of kinetic energy that can be absorbed by plastic deformation can be freely set. Therefore, it is possible to efficiently absorb energy by providing a precompression spring unit having optimum characteristics for a cab overtrack having a different vehicle body structure and loadable weight.

  Moreover, the pre-compression spring unit 71 can be made to function using the U bolt 37 generally used for the fixing structure of the loading platform 7, and versatility is high.

  In this embodiment, the hollow spring 73 is used, but a solid spring may be used. In this case, energy absorption due to plastic deformation of the spring itself cannot be expected, but energy absorption can be increased by energy absorption due to elastic deformation as compared with the rigid body connection using the cargo bed stopper member 53, and a cab living space is secured. can do.

  Further, although the precompression spring unit 71 is provided in place of the cargo bed stopper member 53, both the cargo bed stopper member 53 and the precompression spring unit 71 may be provided.

  Further, it is preferable that the same number of pre-compression spring units 71 be provided on the side members 3 on both sides in the vehicle width direction of the vehicle.

  Further, the precompression spring unit 71 may be directly connected to the vertical joist 17 without using the wire 93, for example, as shown in FIG. In the structure of FIG. 10, the vertical joist 17 is formed shorter than the loading platform 7 and the side member 3 at the rear end portion of the vehicle, whereby the precompression spring unit 71 is placed between the loading platform 7 and the side member 3. A housing space is defined. The fixing flange portions 89 and 91 of the spring case 75 are fastened and fixed to the upper wall 31 while being in surface contact with the upper surface of the upper wall 31 of the side member 3. Thereby, the precompression spring unit 71 is fixed to the side member 3, and the side opening 75 c of the spring case 75 is closed by the upper wall 31 of the side member 3 in this state. The upper surface of the spring case 75 is in surface contact with the lower surface of the bottom plate 15 of the loading platform 7 and supports the loading platform 7 from below. The vertical joist 17 has a rear end vertical wall 99 at the rear end portion thereof, and an insertion hole (not shown) for the spring shaft 81 is formed in the rear end vertical wall 99. The front end portion 81 a of the spring shaft 81 is inserted through the insertion useful hole of the rear end vertical wall 99, and the rear end vertical wall 99 is fastened and held between the spring holding nut 83 and the connecting nut 87.

  In the above configuration, since the forward load on the loading platform 7 side is directly input to the precompression spring unit 71, the kinetic energy absorption by the precompression spring unit 71 can be performed more stably. In addition, since a connecting member such as the wire 93 is not required, the structure can be simplified.

It is a model side view of the cab overtrack concerning this embodiment. It is the II section enlarged view of FIG. It is a perspective view which shows typically the principal part of this embodiment. It is a disassembled perspective view of a precompression spring unit. It is sectional drawing of a hollow spring. It is a model side view of the cab overtrack at the time of front collision. It is a side view which shows typically the inside of a precompression spring unit, (a) represents the initial state, (b) represents the time of elastic deformation, and (c) represents the time of plastic deformation. It is a graph which shows the relationship between the load and the displacement to the front of the loading platform side at the time of frontal collision at the time of using the precompression spring unit of this embodiment. It is a graph which shows the relationship between the load and the displacement to the front of the loading platform side at the time of frontal collision at the time of using the loading platform stopper member which is a comparison object. It is a principal part side view which shows the modification of this embodiment.

Explanation of symbols

1 Cab over track 3 Side member (frame side member)
5 Cab 7 Loading platform 17 Vertical joist 37 U bolt 71 Precompression spring unit 73 Hollow spring 73
75 Spring case 75
77, 79 Spring holder plate 81 Spring shaft 93 Wire (connection member)

Claims (4)

A loading platform fixing structure for connecting the loading platform side to the frame side member,
A vertical joist is fixed to the bottom of the loading platform,
A precompression spring unit comprising a spring, a spring case, a rear spring holder plate, and a spring shaft is disposed between the cargo bed and the frame side member;
The spring case is box-shaped, has an opening on the front surface thereof, and is fixed to the upper surface of the side member,
The rear spring holder plate is accommodated in the spring case and is movable in the vehicle front-rear direction.
The spring shaft has a front end fixed to the vertical joist and a rear end fixed to the rear spring holder plate, and extends in the vehicle front-rear direction in a state of being inserted through the opening.
The spring is compressed between the front surface portion and the rear spring holder plate in a state where the spring is compressed in the vehicle front-rear direction so that an urging force in the extension direction acts on the front surface portion and the rear holder plate. Housed in
When the vertical joist moves relative to the frame side member toward the front of the vehicle, a compressive force acts on the spring. A loading platform fixing structure for connecting the loading platform side to the frame side member,
A vertical joist is fixed to the bottom of the loading platform,
The vertical joists are connected to the frame side members by U-bolts,
A pre-compression spring unit having a spring compressed so that an urging force in an extending direction acts on the frame side member;
The U bolt, the precompression spring unit, and the pre-compression spring unit so that a compression force acts on the spring by tilting the U bolt forward of the vehicle when the cargo bed side moves relative to the frame side member forward of the vehicle. The cargo bed fixing structure, wherein the two are connected by a connecting member. The loading platform fixing structure according to claim 2,
The pre-compression spring unit has a spring shaft that compresses the spring by moving forward of the vehicle,
The loading structure of the loading platform, wherein the spring shaft is connected to the loading platform side . A fixing structure of a cargo bed according to any one of claims 1 to 3,
The loading platform fixing structure , wherein the spring is a hollow spring formed of a tubular body .

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