JP2007276687A - Movable type rear bumper device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a movable type rear bumper device devised capable of easily changing a rear bumper over to a projecting position to the rear side of a vehicle body and to a storing position to the lower side of the vehicle body in travelling. <P>SOLUTION: This movable type rear bumper device is provided with the rear bumper 12 projected and provided on a supporting shaft 10 free to rotate horizontally installed on a rear part of a vehicle body of a dump truck, a driving shaft 30 connected to an air cylinder 20 and a transmission mechanism 40 to transmit the revolution of the driving shaft 30 to the supporting shaft 10. The transmission mechanism is provided with a connecting rod 43 one end of which is pivotally installed on a driven arm 41 projected and provided at the supporting shaft 10 and a bell crank 45 one end of which is connected to the other end of this connecting rod and the other end of which is pivotally installed on an oscillating arm 44 projected and provided at the driving shaft, and a stopper 50 to avoid the upward movement of the rear bumper when the rear bumper is positioned at a dead point impossible to move a pivotally supporting point of the oscillating arm and the bell crank in a travelling state to move to the rear of the vehicle body by force from the rear bumper side and the rear bumper at a vehicle body rear position is applied with a force from below is provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a movable rear bumper device in a dump truck in which, for example, a cargo bed is inclined rearward and a load is discharged from the rear of the cargo bed.

  Conventionally, in a dump truck, when a loading platform, such as earth and sand, is discharged from the rear of the loading platform by tilting the loading platform rearward, the rear bumper is buried in the discharging soil and the like, and there is a risk of deformation, breakage, and the like. Further, when asphalt finisher vehicles are thrown into the asphalt finisher vehicle by a dump truck, if the dump truck is brought close to the asphalt finisher car, the rear bumper becomes a protrusion obstacle, which causes inconvenience in asphalt throwing.

  As means for solving these problems, a method of moving the rear bumper by a drive cylinder is employed. As this movable rear bumper device, as shown in FIG. 5, for example, a rear bumper b is fixed to the tip of an arm a that is swingably suspended on both sides of the rear part of the vehicle body, and one end pivots on the tip of the arm a. The other end portion of the first link c to be attached and the other end portion of the second link d, one end of which is pivotally attached to the vehicle body side, are pivotally attached via a pin e and can be swung to the vehicle body side. There is known a rear bumper device in which a drive piston g of a drive cylinder f attached to the vehicle is pivotally attached to the second link d via a pin h.

  According to this rear bumper device, the rear bumper b can be switched and moved between the protruding position on the rear side of the vehicle body and the retracted position on the lower side of the vehicle body by driving the drive cylinder f. In FIG. 5, symbol i is a stopper provided on the vehicle body side and engaged with the second link d.

As another movable rear bumper device, there is also known a structure in which a rear bumper is fixed to a moving means, for example, a drive piston of a hydraulic cylinder, and the rear bumper is movable in the front-rear direction of the vehicle body by driving the hydraulic cylinder (for example, Patent Document 1).
Japanese Utility Model Publication No. 5-32164 (Scope of Claim for Utility Model Registration, FIG. 1)

  However, the conventional rear bumper device shown in FIG. 5 has a structure in which a link mechanism for operating the rear bumper and a cylinder for driving the link mechanism are provided on both sides of the vehicle. There was a problem that work was troublesome. Further, since the impact force at the time of collision is received by the link, it is necessary to make the link mechanism robust, and there is a problem that the weight of the vehicle body increases.

  Further, since the rear bumper is moved by driving the cylinder in the one disclosed in Japanese Utility Model Publication No. 5-32164, the structure can be simplified as compared with the case where a link mechanism is provided. In addition, since the cylinder receives the impact force at the time of collision, the cylinder needs to have a robust structure, and there is a problem that the weight of the vehicle body increases. In addition, since the cylinder is disposed in a limited space on both sides of the rear part of the vehicle body, there is a problem that the movement of the rear bumper cannot be secured sufficiently.

  The present invention has been made in view of the above circumstances so that one reciprocating drive means can easily switch the rear bumper between a projecting position to the rear side of the vehicle body when traveling and a retracted position to the lower side of the vehicle body when raising and lowering the loading platform. An object of the present invention is to provide a movable rear bumper device.

  In order to achieve the above object, a movable rear bumper device of the present invention includes a support shaft that is rotatably mounted on the rear part of a vehicle body of a dump truck, a vehicle body rear side projecting from the support shaft via a bracket, and A rear bumper movable to the lower side of the vehicle body, a rotatable drive shaft coupled to the reciprocating drive means, and the drive shaft for moving the rear bumper to a rear side position of the vehicle during traveling and a retracted position below the vehicle body A transmission mechanism that transmits the rotation of the connecting rod to the support shaft, the transmission mechanism including a connecting rod having one end pivotally attached to a driven arm protruding from the supporting shaft, and the other end of the connecting rod. And a bell crank pivotally attached to a swinging arm projecting from the drive shaft, and the rear bumper is located at the rear of the vehicle body. When the pivot point of the swing arm and bell crank is located at the dead center where it cannot move due to the force from the rear bumper side, and the rear bumper at the rear of the vehicle body receives a force from below when traveling, the rear bumper A stopper is provided to prevent the upper part from moving upward (Claim 1).

  In the present invention, the bell crank straddles the top of the drive shaft, the other end of the bell crank is positioned on the traveling front side of the vehicle body, and the bell crank and the rocker in a traveling state in which the rear bumper moves to the rear of the vehicle body. The pivot point with the moving arm can be configured to be positioned below the axis of the drive shaft.

  Further, the reciprocating means is formed by an air cylinder having a telescopic drive piston, and an air tank is connected to a port communicating with a chamber defined by the drive piston in the air cylinder via a three-position switching means. It can be set as a structure (Claim 3).

  According to the first and second aspects of the present invention, the rear bumper can be stored on the lower side of the vehicle body via the transmission mechanism by one reciprocating means and can be protruded on the rear side of the vehicle body. Also, during normal driving, the pivoting point of the swing arm and bell crank projecting on the drive shaft is positioned at the dead point where it cannot move due to the force from the rear bumper side in the state of projecting to the rear side of the vehicle body. The impact force at the time of collision can be received by the support shaft, and no load acts on the reciprocating drive means. Further, for the force applied downward on the upper part of the rear bumper, a force that causes the rear bumper to further protrude toward the rear of the vehicle body acts because the pivotal support point of the swing arm and the bell crank is at the dead center position. In addition, against the force applied upward from the lower part of the rear bumper, the stopper prevents the rear bumper from moving upward.

  According to the third aspect of the present invention, the reciprocating means is formed by an air cylinder having a telescopic drive piston, and the three-position switching means is connected to a port communicating with the chamber defined by the drive piston in the air cylinder. By connecting the air tank through the air source, it is possible to switch the protrusion and storage movement of the rear bumper in a short time by the air source and to maintain the protrusion state.

  As described in detail above, since the movable rear bumper device of the present invention is configured as described above, the following excellent effects can be obtained.

  (1) According to the first aspect of the present invention, the rear bumper can be stored on the lower side of the vehicle body via the transmission mechanism by one reciprocating means and can be protruded on the rear side of the vehicle body. The rear bumper can be retracted and the rearward projecting to the rear side of the vehicle can be easily switched according to the case where the load of the vehicle is tilted and the load is discharged or the vehicle is traveling. Also, during normal driving, the pivoting point of the swing arm and bell crank projecting on the drive shaft is positioned at the dead point where it cannot move due to the force from the rear bumper side in the state of projecting to the rear side of the vehicle body. The impact force at the time of the collision can be received by the support shaft, and the influence on the reciprocating drive means by the impact force at the time of the collision can be eliminated. In addition, for the downward force applied to the upper part of the rear bumper, the force that causes the rear bumper to protrude further toward the rear side of the vehicle acts due to the relationship between the pivot point of the swing arm and the bell crank at the dead center position. Since the stopper prevents the upward movement of the rear bumper with respect to the force applied upward, the strength of the rear bumper can be maintained.

  (2) According to the invention described in claim 2, the bell crank constituting the transmission mechanism straddles the upper portion of the drive shaft, the other end of the bell crank is positioned on the traveling front side of the vehicle body, and the rear bumper is disposed on the rear side of the vehicle body. In addition to the above (1), the structure of the transmission mechanism is further simplified by configuring the pivot point of the bell crank and the swinging arm to be located below the axis of the drive shaft in the traveling state in which In addition, since the force that causes the rear bumper to protrude rearwardly more reliably acts against the downward force applied to the upper portion of the rear bumper, the strength of the rear bumper can be further improved.

  (3) According to the invention described in claim 3, since the protrusion and storage movement of the rear bumper can be switched in a short time by the air source and the protruding state can be maintained, the above (1), (2) In addition, the position of the rear bumper can be changed quickly and reliably.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing an example of a movable rear bumper device according to the present invention, FIG. 2 is a schematic side view showing a main portion of the movable bumper device, and FIG. 3 is a main portion of the movable bumper device. It is a schematic plan view which shows.

  The movable rear bumper device includes a support shaft 10 that is rotatably mounted on the rear portion of the vehicle body of the dump truck 1, and a vehicle body rear portion that protrudes from the support shaft 10 via a bracket 11 at both ends of the support shaft 10. A rear bumper 12 movable to the side and the vehicle body lower side, a rotatable drive shaft 30 connected to a drive piston 21 (hereinafter referred to as a piston rod 21) of an air cylinder 20 as reciprocating drive means, and a rear bumper 12 traveling It is mainly composed of a position at the rear side of the vehicle body at the time and a transmission mechanism 40 that transmits the rotation of the drive shaft 30 to the support shaft 10 so as to move to the retracted position below the vehicle body.

  The support shaft 10 is horizontally supported by a pair of left and right mounting brackets 14 fixed to the left and right end portions of the rear end portion of the chassis frame 2 by, for example, fixing bolts 13. In this case, a sleeve 15 is fixed in a mounting hole 14 a provided in the mounting bracket 14 by welding or the like, for example, and the support shaft 10 is rotatably supported in the sleeve 15. Further, a bracket 11 is fixed to the sleeve 16 by, for example, welding or the like, at an outer end portion of the sleeve 15 in the support shaft 10, and the sleeve 16 and the support shaft 10 are fixed to each other via a pin 17. A rear bumper 12 is fixed to the rear projecting portion of the vehicle body 11.

  The transmission mechanism 40 has a connecting rod 43 whose one end is pivotally connected to a driven arm 41 protruding from the support shaft 10 via a pin 42a, one end connected to the other end of the connecting rod 43, and the other end connected to the connecting rod 43. A bell crank 45 pivotally attached to a swing arm 44 projecting from the drive shaft 30 via a pin 42b. In this case, the bell crank 45 is formed in a substantially square shape in a side view and is disposed so as to straddle the upper part of the drive shaft 30, and the swing arm 44 in a state in which the rear bumper 12 is located at the rear of the vehicle body. The pivot point P1 of the bell crank 45 is located at the dead point where it cannot move due to the force F1 from the rear bumper side. That is, as shown in FIG. 2, the pivot point P <b> 1 is located below the axial center point P <b> 2 of the drive shaft 30 in a state where the rear bumper 12 is located behind the vehicle body.

  Note that both ends of the drive shaft 30 are rotatably supported by a bearing bracket 31 fixed to the chassis frame 2 (see FIG. 3). The piston rod 21 of the air cylinder 20 is pivotally attached to the distal end portion of the drive transmission arm 32 projecting from the drive shaft 30 via a pin 42c. The transmission mechanism 40 is disposed at the center position of the vehicle body.

  Further, on the vehicle body side, for example, the chassis frame 2, a stopper 50 is provided that prevents the rear bumper 12 from moving upward when the rear bumper 12 located at the rear of the vehicle body receives a force F3 from below during traveling ( (See FIG. 2). In this case, the stopper 50 is fixed to the mounting bracket 14 by welding or the like, and the rear surface (front side surface in the traveling direction) of the bracket 11 is engaged with the stopper 50.

  On the other hand, the air cylinder 20 is connected to ports 23a and 23b communicating with chambers 22a and 22b defined by the piston rod 21 via a four-port three-position switching valve 24 (hereinafter referred to as a switching valve 24) which is a three-position switching means. Connected to the air tank 25. In this case, as shown in FIG. 1, the switching valve 24 has a first port 24 a communicating with the port 23 a of the air cylinder 20 via the first conduit 26 a and a second port 24 b of the air cylinder 20. A second port 24b communicating with the pipe line 26b, a third port 24c connected to the air tank 25 via a supply pipe line 27, and a fourth port 24d opened to the atmosphere are provided. Further, the switching valve 24 includes a storage position portion 28a having a flow path that communicates the first port 24a and the third port 24c, and a flow path that communicates the second port 24b and the fourth port 24d. The travel position portion 28b (neutral position portion) that makes the first to fourth ports 24a to 24d intermittent, the flow path that connects the first port 24a and the fourth port 24d, and the second port 24b The return position portion 28c having a flow path that communicates with the third port 24c is formed to be switchable. The switching valve 24 configured as described above is switched by operation of a switching switch (not shown) in the cab of the dump truck 1. Note that the changeover switch may be interlocked with the tilting of the loading platform.

  In the movable rear bumper device configured as described above, during normal traveling, the switching valve 24 is moved to the traveling position portion 28b (neutral position portion) as shown in FIGS. In a state where air is enclosed in the chambers 22a and 22b of the air cylinder 20, the pivot point P1 of the bell crank 45 and the swing arm 44 of the transmission mechanism 40 is positioned at a dead center where it cannot move due to the force F1 from the rear bumper side. is doing. That is, the pivot point P1 is located below the axial point P2 of the drive shaft 30. Thereby, the rear bumper 12 can receive a load by the support shaft 10 without moving around the support shaft 10 by the force F1 from the rear. Therefore, the air cylinder 20 is not affected by the impact force at the time of collision.

  When the switching valve 24 is switched to the storage position portion 28a, air is supplied from the air tank 25 into the chamber 22a of the air cylinder 20 through the supply conduit 27 and the first conduit 26a, while in the chamber 22b. The air is discharged to the atmosphere side through the second conduit 26b, and the piston rod 21 extends (moves in the right direction in FIG. 4) as shown in FIG. 4B. Then, the drive shaft 30 rotates in the clockwise direction in FIG. 4 via the drive transmission arm 32 pivotally attached to the piston rod 21, and the swing arm 44 rotates, and the bell crank pivotally attached to the swing arm 44. Similarly, the follower arm 41 and the support shaft 10 are rotated clockwise via the connecting rod 43 and the connecting rod 43 to move the rear bumper 12 to the retracted position below the chassis frame 2.

  In order to switch the rear bumper 12 from the retracted position to the traveling position, the switching valve 24 is switched to the return position portion 28c, the rear bumper 12 is moved to the rear position of the vehicle body, and then the switching valve 24 is moved to the traveling position portion 28b (neutral position). Switching to the position portion).

It is a schematic structure figure showing an example of a movable rear bumper device concerning this invention. It is a schematic side view which shows the principal part of the said movable bumper apparatus. It is a schematic plan view which shows the principal part of the said movable bumper apparatus. It is a schematic side view which shows the switching operation | movement of the said movable bumper apparatus. It is a schematic block diagram which shows an example of the conventional movable rear bumper apparatus.

Explanation of symbols

1 dump truck 10 support shaft 11 bracket 12 rear bumper 20 air cylinder (reciprocating drive means)
21 Piston rod (drive piston)
22a, 22b Chamber 24 4 port 3 position switching valve (3 position switching means)
28a Storage position part 28b Traveling position part (neutral position part)
28c Return position portion 30 Drive shaft 32 Drive transmission arm 40 Transmission mechanism 41 Driven arm 43 Connecting rod 44 Swing arm 45 Bell crank 50 Stopper P1 Pivot point P2 Axis point of drive shaft

Claims (3)

A support shaft that is rotatably mounted horizontally at the rear of the body of the dump truck;
A rear bumper that protrudes from the support shaft via a bracket and is movable toward the vehicle rear side and the vehicle body lower side;
A rotatable drive shaft coupled to the reciprocating drive means;
A transmission mechanism for transmitting the rotation of the drive shaft to the support shaft in order to move the rear bumper to a rear position of the vehicle body during traveling and a storage position below the vehicle body;
The transmission mechanism includes a connecting rod having one end pivotally attached to a follower arm protruding from the support shaft, and a swing having one end connected to the other end of the connecting rod and the other end protruding from the drive shaft. A bell crank pivotally attached to the moving arm,
The pivot point of the swing arm and bell crank in the state where the rear bumper is located at the rear of the vehicle body is located at the dead point where it cannot move due to the force from the rear bumper side,
And, when the rear bumper located at the vehicle body rear position during traveling receives a force from below, a stopper is provided to prevent the rear bumper from moving upward.
A movable rear bumper device characterized by that. The movable rear bumper device according to claim 1,
The bell crank straddles the upper part of the drive shaft, the other end of the bell crank is located on the traveling front side of the vehicle body, and the bell crank and the swing arm are in a traveling state in which the rear bumper is moved to the rear of the vehicle body. A movable rear bumper device, wherein the pivot point is located below the axis of the drive shaft. The movable rear bumper device according to claim 1 or 2,
The reciprocating means is formed by an air cylinder having a retractable drive piston, and an air tank is connected to a port communicating with a chamber defined by the drive piston in the air cylinder via a three-position switching means. A movable rear bumper device characterized by that.

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