Rear door closing gear of cargo box of dump truck

Abstract

To provide a rear door closing gear of the cargo box of a dump truck which can enhance a loaded article's discharge performance and prevent a rear door with the rear opening part of the cargo box left open from damaging when the cargo box is tilted to unloading the loaded article of the dump truck.SOLUTION: This rear door closing gear comprises a rear door 7 for opening and closing the rear door opening part 5a of a cargo box 5 tiltable with respect to a chassis 2 and a closing mechanism 8 of the rear door 7. The rear door 7 has an upper door 71 and a lower door 72, where the upper end part of the upper door 71 is attached to be rotatable around the axis in a vehicle width direction with respect to the rear opening part 5a, and where the upper end part of the lower door 72 is attached to be rotatable around the axis in the vehicle width direction with respect to the lower end part of the upper door 71. The closing mechanism 8 is so constituted as to increase the opening angle of the lower door 72 with respect to the upper door 71 as the opening angle of the upper door 71 increases with respect to the rear opening part 5a.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a rear door opening / closing device for a loading box of a dump vehicle, which includes a rear door for opening and closing a rear opening of a loading box tiltable with respect to a vehicle body, and an opening / closing mechanism for the rear door.

Background Art

[0002] Conventionally, a dump vehicle including a loading box (loading platform) tiltable with respect to a vehicle body and a rear door (gate) for opening and closing a rear opening of the loading box is known (see, for example, Patent Document 1). In a conventional dump vehicle, the rear door is formed as a single piece. The rear door is attached to the rear end portion of the loading box by an upper hinge. When the loading box is in a horizontal state, the rear door is in a position closing the rear opening. On the other hand, when the loading box is in an inclined state, the rear door is opened downward about the upper hinge by the action of gravity. Thereby, the rear opening is opened. When the loading box loaded with the load is inclined, the load is unloaded from the rear opening to the ground.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional dump truck such as Patent Document 1, when the load is unloaded and the load is piled up on the ground and forms a lump of load, the opened rear door is likely to come into contact with this lump of load. When this contact occurs, there are problems that all the load cannot be discharged from the load box or the rear door is damaged. Therefore, conventionally, during unloading, it has been required to limit the dump angle or take time to unload so as not to contact the lump of load on the ground that has been unloaded first. In particular, when unloading the load in a dump truck equipped with a load box and a rear door having a large dimension in the height direction, it is necessary to incline the load box greatly in order to finish unloading as soon as possible, and the above problems occur more significantly.

[0005] FIG. 8 is a side view showing an image in which the rear door 700 is deformed during unloading in a conventional dump truck 100. As shown in FIG. 8, the conventional dump truck 100 includes a load box 500 that is tiltable with respect to the vehicle body 200, and a rear door 700 that opens and closes the rear opening 500a of the load box 500. The load box 500 has a larger dimension in the height direction compared to a normal dump truck for transporting earth and sand. The rear door 700 is formed of a single piece. The rear door 700 is attached to the rear end portion of the load box 500 by an upper hinge 700a. Since the rear door 700 is formed in accordance with the height dimension of the load box 500, it has a large dimension in the height direction. In the conventional dump truck 100 equipped with such a rear door 700, during unloading of the load L, the lower part of the rear door 700 is buried in the lump of the load L on the ground G that has been unloaded first. When this happens, a large load is applied to the rear door 700 by the load L, and the rear door 700 is greatly curved. The load L remaining inside the load box 500 is not discharged smoothly. In the worst case, the rear door 700 may buckle and the rear door 700 may be damaged.

[0006] The present invention has been made in consideration of the above circumstances, and an object thereof is to provide a rear door opening / closing device for a load box of a dump truck that can improve the dischargeability of the load when the load box is inclined to unload the load of the dump truck and prevent the rear door that opens the rear opening of the load box from being damaged.

Means for Solving the Problem

[0007] The invention disclosed in this specification is configured as follows in order to solve the above problems. That is, the first invention includes a rear door that opens and closes a rear opening of a load box that is tiltable with respect to a vehicle body, and an opening / closing mechanism for the rear door. The rear door has an upper door and a lower door. The upper end of the upper door is rotatably attached around an axial center in the vehicle width direction with respect to the rear opening. The upper end of the lower door is rotatably attached around an axial center in the vehicle width direction with respect to the lower end of the upper door. The opening / closing mechanism is configured to increase the opening angle of the lower door with respect to the upper door as the opening angle of the upper door with respect to the rear opening increases. Further, the opening / closing mechanism includes an interlocking wire for interlocking the movement of the upper door with respect to the rear opening and the movement of the lower door with respect to the upper door, and a pulley for bending the interlocking wire. The pulley has a first pulley provided on the upper door and a second pulley provided on the upper door so as to be positioned below the first pulley. Both ends of the interlocking wire are attached to an upper end fixing portion of the load box and a lower end fixing portion of the lower door. The interlocking wire is configured to start from the upper end fixing portion, be passed over the first pulley and the second pulley in this order, and reach the lower end fixing portion.

[0008] According to the first invention, the rear door has an upper door and a lower door. Further, the opening and closing mechanism is configured to increase the opening angle of the lower door with respect to the upper door as the opening angle of the upper door with respect to the rear opening of the load box increases. Thereby, when the upper door of the load box is tilted to unload the loaded goods, the lower door can be flipped upward and backward with respect to the upper door. That is, compared with the conventional single-piece rear door, the position of the lower part of the rear door can be moved further backward and upward. Thereby, during unloading, the rear door can be prevented from contacting the pile of loaded goods on the ground that has been unloaded first. As a result, all the loaded goods can be discharged from the load box in a short time. In addition, it is possible to prevent the rear door from being damaged by contact with the pile of loaded goods on the ground. Further, even in a dump truck equipped with a load box having a large dimension in the height direction, a sufficient dump angle can be ensured.

[0009] Further, since the opening and closing mechanism includes an interlocking wire for interlocking the movement of the upper door with respect to the rear opening and the movement of the lower door with respect to the upper door, and a pulley for bending the interlocking wire, a configuration for interlocking the upper door and the lower door can be realized with a simple configuration and low cost.

[0010] The pulley has a first pulley and a second pulley, and the interlocking wire is configured to start from the upper end fixing portion, be hung over the first pulley and the second pulley in this order, and reach the lower end fixing portion. Thereby, when the upper door opens with respect to the rear opening due to the action of gravity applied to the rear door, the movement is transmitted to the lower door, and the lower door can be flipped upward and backward with respect to the upper door. Thereby, gravity can be effectively utilized not only for the operation of the upper door but also for the operation of the lower door.

Effect of the Invention

[0011] According to the rear door opening and closing device of the load box of the dump truck according to the present invention, when the load box is tilted to unload the loaded goods of the dump truck, the dischargeability of the loaded goods can be improved, and it is possible to prevent the rear door that has opened the rear opening of the load box from being damaged.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0014] FIG. 1 is a side view of a dump truck 1 equipped with a rear door opening / closing device E according to an embodiment of the present invention. FIG. 2 is a side view of the dump truck 1 showing the inside of the loading box 5 with the load L loaded. As shown in FIGS. 1 and 2, the dump truck 1 of the present embodiment includes a vehicle body 2, a loading box 5 tiltable with respect to the vehicle body 2, and a rear door opening / closing device E. The vehicle body 2 includes a chassis frame 2a extending in the longitudinal direction of the vehicle and a cab 2b provided at the front part on the chassis frame 2a. A sub-frame 3 extending in the longitudinal direction of the vehicle is attached to the chassis frame 2a behind the cab 2b. At the rear end of the sub-frame 3, the loading box 5 is tiltably attached by a dump hinge 6. In the present embodiment, the tilting of the loading box 5 is performed by driving a hoist-type tilting device 4 (see FIG. 7) interposed between the loading box 5 and the sub-frame 3. The hoist-type tilting device 4 is composed of a hydraulic cylinder, a plurality of link members, and the like.

[0015] As shown in FIG. 2, the loading box 5 has a bottom wall portion 52, a front wall portion 53, a pair of side wall portions 54, 54 in the vehicle width direction, and a loading box bottom frame 51. The loading box bottom frame 51 is attached to the bottom surface of the bottom wall portion 52 so as to extend from the front end to the rear end of the loading box 5. The loading box bottom frame 51 is connected to the sub-frame 3 and the dump hinge 6. The upper end of the loading box 5 is open, and the load L can be loaded from above the loading box 5. Note that a lid that can be opened and closed may be provided at the upper end of the loading box 5. The rear end of the loading box 5 is open, and a rear opening 5a is formed by the rear ends of the bottom wall portion 52 and the pair of side wall portions 54, 54. The loading box 5 of the present embodiment is set to have a larger dimension in the height direction compared to that for transporting earth and sand. The loading box 5 of the present embodiment is for transporting light specific gravity materials such as industrial waste and construction waste. A dump truck 1 equipped with such a loading box 5 is generally called by names such as a deep tilt dump or an earth and sand prohibited dump.

[0016] Figure 3 is a front view of the rear door opening / closing device E. Figure 4 is an enlarged view of the main part of Figure 3. Figure 5 is an enlarged side view of the main part showing the rear door opening / closing device E and its peripheral part in Figure 1. As shown in Figures 3 to 5, the rear door opening / closing device E includes a rear door 7 and a pair of opening / closing mechanisms 8, 8 in the vehicle width direction. The rear door 7 is formed in a substantially rectangular shape as a whole. The rear door 7 opens and closes the rear opening 5a of the cargo box 5. Since the dimension in the height direction of the cargo box 5 is set large, the dimension in the height direction of the rear door 7 is also formed large.

[0017] The rear door 7 has a substantially rectangular upper door 71 and a substantially rectangular lower door 72. The area of the main surface of the upper door 71 is larger than the area of the main surface of the lower door 72. Therefore, also in terms of weight, the upper door 71 is larger than the lower door 72. An upper hinge 71a is provided at the upper end of the upper door 71. By this upper hinge 71a, the upper door 71 is rotatably attached to the rear opening 5a about the vehicle width direction axis. The upper end of the lower door 72 is rotatably attached to the lower end of the upper door 71 about the vehicle width direction axis by a hinge 73.

[0018] The opening / closing mechanism 8 includes an interlocking wire 81 for interlocking the movement of the upper door 71 with respect to the rear opening 5a and the movement of the lower door 72 with respect to the upper door 71, and a pulley 82 for bending the interlocking wire 81. Both ends of the interlocking wire 81 are attached to an upper end fixing portion 85 and a lower end fixing portion 86. The upper end fixing portion 85 is provided at the rear end and upper position of the side wall portion 54. The upper end fixing portion 85 is provided on the outer surface of the side wall portion 54. The lower end fixing portion 86 is provided on a protruding member 84. This protruding member 84 is provided on the outer surface of the lower door 72 so as to protrude rearward of the vehicle from the substantially central height position in the vertical direction of the lower door 72.

[0019] The pulley 82 has a first pulley 821 provided on the upper door 71 and a second pulley 822 provided on the upper door 71 so as to be positioned below the first pulley 821. Also, in the closed state where the rear door 7 closes the rear opening 5a, as shown in FIG. 5, the first pulley 821 is disposed at a position higher than the upper end fixing portion 85. Further, in the closed state, the second pulley 822 is disposed at a position lower than the upper end fixing portion 85. Further, in the closed state, the first pulley 821 and the second pulley 822 are disposed at positions higher than the lower end fixing portion 86.

[0020] As shown in FIG. 4, the first pulley 821 has a pulley body 821a and a body fixing portion 821b. The body fixing portion 821b is attached to the outer surface (rear side of the vehicle) of the upper door 71 and at a position at the end in the vehicle width direction. The body fixing portion 821b supports the pulley body 821a so as to be rotatable about the vehicle width direction axis. Further, the body fixing portion 821b supports the pulley body 821a so that the pulley body 821a projects further outward from the end in the vehicle width direction of the upper door 71.

[0021] The second pulley 822 has a pulley body 822a and a body fixing portion 822b. The body fixing portion 822b is attached to the outer surface (rear side of the vehicle) of the upper door 71 and at a position at the end in the vehicle width direction. The body fixing portion 822b supports the pulley body 822a so as to be rotatable about the vehicle width direction axis. Further, the body fixing portion 822b supports the pulley body 822a so that the pulley body 822a projects further outward from the end in the vehicle width direction of the upper door 71.

[0022] As shown in Fig. 5, the interlocking wire 81 is configured to start from the upper end fixing portion 85, be passed over the first pulley 821 and the second pulley 822 in this order, and reach the lower end fixing portion 86 of the lower door 72. The interlocking wire 81 is bent with respect to the first pulley 821 so as to have a vertex at an obliquely upper position toward the rear of the vehicle. The interlocking wire 81 is bent with respect to the second pulley 822 so as to have a vertex at the front position of the vehicle. As shown in Fig. 4, the interlocking wire 81 is disposed so as to protrude further outward from the end in the vehicle width direction of the rear door 7 as a whole.

[0023] Fig. 6 is an enlarged side view of the main part showing the state in which the loading box 5 is tilted and the rear door opening / closing device E is operated to open from the state of Fig. 5. As shown in Fig. 6, when the loading box 5 is tilted for unloading, when a locking device (not shown) that has fixed the rear door 7 in the closed state is released, the upper door 71 opens with respect to the rear opening 5a due to the action of gravity applied to the rear door 7. Then, the opening / closing mechanism 8 transmits the movement of the upper door 71 to the lower door 72 by the interlocking wire 81, so that the lower door 72 is flipped upward to the rear with respect to the upper door 71. The opening / closing mechanism 8 increases the opening angle of the lower door 72 with respect to the upper door 71 as the opening angle of the upper door 71 with respect to the rear opening 5a increases.

[0024] Fig. 7 is a side view of the dump truck 1 in which the loading box 5 is tilted and the rear door opening / closing device E is operated to open. As shown in Fig. 7, in the dump truck 1 equipped with the rear door opening / closing device E of the present embodiment, when unloading the load L from the loading box 5, since the lower door 72 is flipped upward to the rear with respect to the upper door 71, even if the loading box 5 is tilted greatly, a sufficient distance can be ensured between the lower end of the rear door 7 and the ground G. Therefore, a clearance space A shown by a two-dot chain line is generated in Fig. 7. The load L is unloaded onto the ground G by also using the clearance space A. Because of this clearance space A, the discharge of the load L is not hindered. Also, the rear door 7 does not contact the mass of the load L on the ground G.

[0025] As described above, the dump truck 1 according to the present embodiment includes a rear door 7 that opens and closes a rear opening 5a of a loading box 5 that is tiltable with respect to a vehicle body 2, and an opening / closing mechanism 8 for the rear door 7. The rear door 7 has an upper door 71 and a lower door 72. The upper end of the upper door 71 is rotatably attached to the rear opening 5a about an axial center in the vehicle width direction. The upper end of the lower door 72 is rotatably attached to the lower end of the upper door 71 about an axial center in the vehicle width direction. The opening / closing mechanism 8 is configured to increase the opening angle of the lower door 72 with respect to the upper door 71 as the opening angle of the upper door 71 with respect to the rear opening 5a increases.

[0026] According to the above configuration, when the loading box 5 is tilted to unload the load L, the lower door 72 can be flipped upward with respect to the upper door 71. That is, compared with the conventional single-piece rear door 700, the position of the lower part of the rear door 7 can be moved further rearward and upward. As a result, during unloading, the rear door 7 can be prevented from contacting the mass of the load L on the ground G that has been unloaded first. As a result, all the load L can be discharged from the loading box 5 in a short time. In addition, it is possible to prevent the rear door 7 from being damaged due to contact with the mass of the load L on the ground G. Further, although it is a dump truck 1 provided with a loading box 5 having a large dimension in the height direction, a sufficient dump angle (loading box tilt angle) can be ensured.

[0027] In the above embodiment, the opening / closing mechanism 8 includes an interlocking wire 81 for interlocking the movement of the upper door 71 with respect to the rear opening 5a and the movement of the lower door 72 with respect to the upper door 71, and a pulley 82 for bending the interlocking wire 81.

[0028] According to the above configuration, a configuration for interlocking the upper door 71 and the lower door 72 can be realized with a simple configuration and low cost.

[0029] In the above-described embodiment, the pulley 82 has a first pulley 821 provided on the upper door 71 and a second pulley 822 provided on the upper door 71 so as to be positioned below the first pulley 821. Both ends of the interlocking wire 81 are attached to the upper end fixing portion 85 of the load box 5 and the lower end fixing portion 86 of the lower door 72. The interlocking wire 81 is configured to start from the upper end fixing portion 85, be passed over the first pulley 821 and the second pulley 822 in this order, and reach the lower end fixing portion 86.

[0030] According to the above configuration, when the upper door 71 opens with respect to the rear opening 5a due to the action of the gravity applied to the rear door 7, the movement is transmitted to the lower door 72, and the lower door 72 can be bounced backward with respect to the upper door 71. As a result, the gravity can be effectively utilized not only for the operation of the upper door 71 but also for the operation of the lower door 72.

[0031] In the above-described embodiment, a pair of opening / closing mechanisms 8 are provided at both ends in the vehicle width direction of the rear door 7. According to this configuration, the upper door 71 and the lower door 72 can be surely interlocked and opened in a well-balanced manner.

[0032] The embodiments disclosed this time are illustrative in all respects and are not a basis for a limiting interpretation. The technical scope of the present invention is not construed only by the above-described embodiments, but is defined based on the description in the claims. Further, the technical scope of the present invention includes all modifications within the meaning and scope equivalent to the claims.

Explanation of Reference Numerals

[0033] 1 Dump truck 2 Chassis 5 Load box 5a Rear opening 7 Rear door 8 Opening / closing mechanism 71 Upper door 72 Lower door 81 Interlocking wire 82 Pulley 85 Upper end fixing portion 86 Lower end fixing portion 821 First pulley 822 Second pulley

Claims

【Claim 1】 A rear door that opens and closes a rear opening of a load box that is tiltable with respect to the vehicle body, and an opening / closing mechanism for the rear door, wherein the rear door has an upper door and a lower door, the upper end of the upper door is rotatably attached to the rear opening about an axial center in the vehicle width direction, the upper end of the lower door is rotatably attached to the lower end of the upper door about an axial center in the vehicle width direction, the opening / closing mechanism is configured to increase the opening angle of the lower door with respect to the upper door as the opening angle of the upper door with respect to the rear opening increases, furthermore, the opening / closing mechanism includes an interlocking wire for interlocking the movement of the upper door with respect to the rear opening and the movement of the lower door with respect to the upper door, and a pulley for bending the interlocking wire, the pulley has a first pulley provided on the upper door and a second pulley provided on the upper door so as to be positioned below the first pulley, both ends of the interlocking wire are attached to an upper end fixing portion of the load box and a lower end fixing portion of the lower door, the interlocking wire is configured to start from the upper end fixing portion, be passed over the first pulley and the second pulley in this order, and reach the lower end fixing portion, A rear door opening / closing device for a load box of a dump vehicle, characterized by the above.

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