Lifting devices and work vehicles

Abstract

To provide a lifting device which has a simple structure and excellent maintainability, and has less trouble, and a work vehicle having the same.SOLUTION: A lifting device 1 includes a lifting table 2, a support member 3 for supporting the lifting table 2, a guide part 4 for liftably guiding the support member 3, and a lifting power transmission mechanism 9. The guide part 4 includes an expandable slide rail 5 and a guide part 6 for grounding. The slide rail 5 has a lower slide member 51, and an upper slide member 53 which brings the position of a lower end of the lower slide member 51 to a lower limit position. An upper end of the upper slide member 53 is configured so as to be liftable between the inside of a cargo box and the upper side of the ceiling wall of the cargo box. The guide part 6 for grounding is mounted on the upper slide member 53 so as to liftably guide the support member 3. The guide part 6 for grounding is configured so as to liftably guide the support member 3 between the inside of the cargo box and a ground surface G.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a lifting device capable of loading and unloading a transported object between the upper surface of the ceiling wall of a vehicle load box and the ground, and a work vehicle equipped with the same.

Background Art

[0002] Conventionally, various disaster prevention vehicles have been devised for rescue activities in fires, shipwrecks, and other accidents. Among disaster prevention vehicles, there are some that carry ladders and boats on the upper surface of the ceiling wall of the vehicle load box and travel. Loading and unloading ladders and boats between the upper surface of the ceiling wall of the vehicle load box and the ground is a difficult task without a device for labor-saving in cargo handling. Therefore, it is conceivable to attach a lifting platform that can be lifted and lowered between the upper surface of the ceiling wall and the ground to the rear of the vehicle load box, and place a transported object such as a boat on this lifting platform and lift and lower it (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a gate plate vertical lifting device for a truck including outer columns located on the left and right of the rear end of a truck cargo loading part, an intermediate column that slides inside the outer columns, a slider that slides inside the outer columns and the intermediate column, and a gate plate attached to the slider. The lifting device of this Patent Document 1 has a drive source, a first string body that connects the outer column and the intermediate column, a second string body that connects the outer column, the intermediate column, and the slider, and a plurality of wheels that support the first and second string bodies and perform direction conversion. This structure can increase the height of the support column only when necessary by combining three cylinders of the outer column, the intermediate column, and the slider.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the lifting device described in Patent Document 1 had many components inside the outer column, including an intermediate column, a slider, a first string-like body, a second string-like body, and multiple wheels. This made it difficult to determine the condition inside the outer column, resulting in poor maintainability. Furthermore, the lifting device described in Patent Document 1 had a structure in which tension was constantly applied to the first string-like body and the second string-like body in order to maintain the position of the intermediate column and the slider. When the vehicle was running, the first string-like body, the second string-like body, and the multiple wheels were subjected to loads due to driving vibrations. This resulted in a problem in that the first string-like body, the second string-like body, and the multiple wheels were prone to failure.

[0006] This invention was made in consideration of the above circumstances, and its purpose is to provide a lifting device and a work vehicle equipped therewith that have a simple structure, excellent maintainability, and few malfunctions. [Means for solving the problem]

[0007] To solve the above-mentioned problems, the invention disclosed herein is configured as follows. In other words, the first invention is a lifting device comprising: a lifting platform on which a transported object is placed; a support member that supports the lifting platform so as to be able to rotate up and down; a guide section that guides the support member so as to be able to move up and down; and a lifting power transmission mechanism that transmits a driving force for lifting to the support member, wherein the guide section includes an extendable slide rail and a grounding guide section, the slide rail has a lower slide member whose lower end is fixed to the lower part of the vehicle cargo box, and an upper slide member that sets the position of the lower end of the lower slide member to its lower limit position and is able to move up and down relative to the lower slide member, the upper end of the upper slide member is configured to move up and down between the inside of the vehicle cargo box and the top of the ceiling wall of the vehicle cargo box, the grounding guide section is attached to the upper slide member so as to set the position of the upper end of the upper slide member to the upper limit position of the support member and guide the support member so as to be able to move up and down, and the grounding guide section is configured to guide the support member so as to be able to move up and down between the inside of the vehicle cargo box and the ground.

[0008] According to the first invention, the guide section that guides the support member of the lifting platform to move up and down is composed of a slide rail that does not move below the bottom of the vehicle cargo box and a grounding guide section. The upper slide member of the slide rail and the grounding guide section guide the support member from inside the vehicle cargo box to above the ceiling wall of the vehicle cargo box. Furthermore, only the grounding guide section of the guide section guides the support member to move up and down between the inside of the vehicle cargo box and the ground. As a result, the support member is guided by the guide section from the ground to a position above the ceiling wall of the vehicle cargo box. With this guide structure, compared to conventional lifting devices in which many parts were provided inside the outer column, the support member and guide section can be configured to be exposed. As a result, it is easier for workers to determine the condition of each part during maintenance, so the lifting device of the first invention has excellent maintainability.

[0009] Furthermore, when the vehicle is in motion, the lifting platform is retracted so that its base is positioned below the vehicle's cargo box, thereby maintaining the slide rail in its most contracted state. This ensures that the weight of the support members is applied to the lifting power transmission mechanism during vehicle operation, while the weight of the slide rail is not. As a result, the load on the lifting power transmission mechanism can be reduced compared to conventional lifting devices that required maintaining the height of the intermediate column and slider during vehicle operation, making the lifting device less prone to failure.

[0010] The second invention further comprises, in the first invention, a ceiling cover that is openably and closably attached to the opening in the ceiling wall of the vehicle cargo box, wherein the ceiling cover is configured to open to a position where it does not contact the upper sliding member when the upper sliding member passes through the opening and is positioned above the ceiling wall, and the ceiling cover is configured to close to cover the upper sliding member when the upper sliding member is positioned inside the vehicle cargo box.

[0011] According to the second invention, when the vehicle is in motion, the ceiling cover covers the upper part of the upper sliding member, thereby preventing the slide rail, grounding guide section, and support member from being exposed to wind and rain. Furthermore, since the ceiling cover is configured to open in a position that does not come into contact with the upper sliding member, the slide rail, including the upper sliding member, will not be damaged by opening and closing the ceiling cover. As a result, the second invention makes the lifting device even less prone to malfunction.

[0012] The third invention is characterized in that, in the second invention, the lifting power transmission mechanism includes a lifting cylinder having a cylinder tube fixed to the vehicle cargo box so as to be in line with the extension and retraction direction of the slide rail and a cylinder rod that is movable up and down relative to the cylinder tube, a rotating body attached to the tip of the cylinder rod via a mounting member and rotatable about a horizontal axis, and a wrap-around transmission body wrapped around the rotating body, with one end attached to the support member and the other end fixed to a fixing part of the vehicle cargo box.

[0013] According to the third invention, the support member can be raised and lowered with a simple configuration.

[0014] The fourth invention is characterized in that, in the third invention, the rotating body is configured to move to a position that protrudes above the ceiling wall from the opening when the upper sliding member is raised to its upper limit position, a contact roller is attached to the mounting member for contacting the lower surface of the ceiling wall, and the contact roller is configured to contact the ceiling cover and push up the ceiling cover before the upper sliding member and the rotating body interfere with the ceiling wall when the upper sliding member is raised.

[0015] According to the fourth invention, the driving force for extending the lifting cylinder is transmitted to the ceiling cover via the mounting member and the contact roller. This eliminates the need for a separate actuator to open and close the ceiling cover, thus simplifying the structure of the lifting device. Furthermore, the contact roller prevents the ceiling cover from hitting the upper sliding member and the rotating body, thereby suppressing failures of the lifting power transmission mechanism and the guide section.

[0016] The fifth invention is a work vehicle equipped with a lifting device according to any one of the first to fourth inventions.

[0017] According to the fifth invention, a work vehicle can be made that has a simple structure, is easy to maintain, and has few breakdowns.

Advantages of the Invention

[0018] According to the lifting device and the work vehicle according to the present invention, the structure is simple, the maintainability is excellent, and the occurrence of failures can be reduced.

Brief Description of the Drawings

[0019] [Figure 1] It is a side view of a work vehicle equipped with a lifting device according to an embodiment of the present invention. [Figure 2] It is a side view of a work vehicle showing that the lifting platform of the lifting device of this embodiment can move up and down between a ground position and a ceiling position. [Figure 3] It is a plan view of a work vehicle equipped with the lifting device of this embodiment. [Figure 4] It is a side view of the main part of the lifting device showing the movement of the horizontal holding member. [Figure 5] It is a side view of the main part of the lifting device showing the movement of the rotating cylinder. [Figure 6] It is a side view of the main part of the lifting device showing the state where the lifting platform is at the loading box floor position. [Figure 7] It is an enlarged view of the area E in FIG. 6. [Figure 8] It is a cross-sectional view taken along the line F-F in FIG. 7. [Figure 9] It is a side view of the main part of the lifting device showing the state where the lifting platform is at the ground position. [Figure 10] It is a side view of the main part of the lifting power transmission mechanism showing the rotating body and its periphery. [Figure 11] It is a side view of the main part of the lifting device showing the state where the lifting platform is at the ceiling position. [Figure 12] It is an enlarged view of the area H in FIG. 11. [Figure 13] It is a hydraulic circuit diagram of the lifting device of this embodiment.

Modes for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0021] Figure 1 is a side view of a work vehicle 100 equipped with a lifting device 1 according to one embodiment of the present invention. Figure 2 is a side view of the work vehicle 100 showing that the lifting platform 2 of the lifting device 1 of this embodiment can move up and down between the ground position and the ceiling position. Figure 3 is a top view of the work vehicle 100 equipped with the lifting device 1 of this embodiment.

[0022] The work vehicle 100 is used as a disaster prevention vehicle for rescue operations in the event of fires, water accidents, etc. As shown in Figures 1 to 3, the work vehicle 100 is equipped with a cab 101 at the front of the vehicle. The work vehicle 100 is equipped with a cargo box 110 behind the cab 101. Various equipment and materials for rescue operations are stored inside the cargo box 110. In addition, a seating area for rescue personnel is provided inside the cargo box 110.

[0023] Side doors 111 are provided on the sides of the cargo box 110. A double-opening rear door 112 is provided on the rear of the cargo box 110. These side doors 111 and rear door 112 are used for the entry and exit of rescue personnel and for loading and unloading of equipment. An air conditioner 115 is installed at the front of the ceiling wall 113 of the cargo box 110. The rear door 112 is a double-opening type that can be rotated in the direction of arrow B, as shown in Figure 3. On the other hand, the upper surface of the ceiling wall 113 of the cargo box 110, behind the position of the air conditioner 115, is a space for loading long and large transport items such as ladders 201 and boats 202.

[0024] As shown in Figures 1 to 3, a lifting device 1 is provided at the rear of the cargo box 110. The lifting device 1 is equipped with a lifting platform 2 that can lift and lower not only various materials and equipment, but also large transport items such as ladders 201 and boats 202. The lifting platform 2 can be adjusted to three different height positions: a ground position where it is in contact with the ground G, a cargo box floor position which is the height of the cargo box 110's floor surface, and a ceiling position which is the height of the cargo box 110's ceiling wall 113. The lifting platform 2 can also be in two states: an upright state as shown in Figure 1 and a horizontal state as shown in Figure 2. When the lifting platform 2 is in the upright state, it can be completely stored inside the cargo box 110. When the lifting platform 2 is in the upright state and stored inside the cargo box 110, the rear door 112 can be closed.

[0025] Figure 4 is a side view of the main part of the lifting device 1 showing the movement of the horizontal holding member 26. Figure 5 is a side view of the main part of the lifting device 1 showing the movement of the rotating cylinder 7. Figure 6 is a side view of the main part of the lifting device 1 showing the state in which the lifting platform 2 is at the floor level of the cargo box.

[0026] As shown in Figures 4 to 6, the lifting device 1 comprises a pair of left and right support members 3 that support the lifting platform 2 so that it can rotate up and down, a pair of left and right guide parts 4 that guide the support members 3 so that they can move up and down, and a pair of left and right lifting power transmission mechanisms 9 that transmit the driving force for lifting to the support members 3. The guide parts 4, the support members 3, and the lifting power transmission mechanisms 9 are provided at the rear end of the cargo box 110 and on the left and right side walls inside the cargo box 110.

[0027] The support member 3 is a plate-shaped member that extends generally in a straight line in the vertical direction. At the lower end of the support member 3, a lifting platform mounting portion 31 is provided so as to protrude toward the rear of the vehicle, for rotatably attaching the base end of the lifting platform 2. Also at the lower end of the support member 3, a transmission body mounting portion 32 is provided so as to protrude toward the front of the vehicle. Furthermore, at the upper end of the support member 3, an upper end projection portion 33 is provided so as to protrude toward the rear of the vehicle. A pair of support members 3 are provided, one on the left and one on the right, to support both the left and right ends (both ends in the vehicle width direction) of the lifting platform 2.

[0028] As shown in Figure 4, the lifting platform 2 can assume two states, a horizontal state and an upright state, by rotatably attaching its base end to the support member mounting portion 21 of the support member 3. A horizontal holding member mounting portion 22 is provided at the tip of the lifting platform 2. An extension base portion 25 is inserted into the tip opening 24 of the lifting platform 2. The extension base portion 25 can be extended and retracted in the direction of arrow D in Figure 4. When the extension base portion 25 is extended from the tip opening 24, the upper surfaces of the lifting platform 2 and the extension base portion 25 become the surface for placing the transported object. Since the area of ​​the transported object placement surface is increased, it becomes possible to stably place long boats 202 and the like.

[0029] The lifting platform 2 and the support member 3 are connected not only by the support member mounting portion 21, but also by the horizontal holding member 26. A pair of horizontal holding members 26 are provided on the left and right sides of the lifting platform 2. The horizontal holding members 26 maintain the horizontal position of the lifting platform 2 by restricting the tip of the lifting platform 2 from rotating downward from the horizontal position when the lifting platform 2 is in a horizontal position. The horizontal holding member 26 has a rod-shaped first link member 26a and a second link member 26b. The first link member 26a and the second link member 26b are connected at an intermediate connecting portion 26c. The end of the first link member 26a opposite to the intermediate connecting portion 26c is connected to the upper end projection 33 of the support member 3. The end of the second link member 26b opposite to the intermediate connecting portion 26c is connected to the horizontal holding member mounting portion 22 of the lifting platform 2.

[0030] When the lifting platform is in a horizontal position, the horizontal holding member 26 is positioned in a straight line and inclined downward from the upper end projection 33 of the support member 3 toward the horizontal holding member mounting portion 22 of the lifting platform 2. The horizontal holding member 26 is designed to fold with the intermediate connecting portion 26c as the lifting platform 2 rotates upward from a horizontal position. When the lifting platform 2 is in an upright position, the first link member 26a and the second link member 26b of the horizontal holding member 26 generally overlap when viewed from the left-right direction (vehicle width direction). When the lifting platform 2 is in an upright position, the first link member 26a and the second link member 26b are positioned to extend in the vertical direction.

[0031] As shown in Figure 5, the lifting platform 2 and the support member 3 are also connected to each other by a rotating cylinder 7. A pair of rotating cylinders 7 are provided on the left and right sides of the lifting platform 2. The rotating cylinders 7 provide the lifting platform 2 with a driving force to rotate it vertically relative to the support member 3. The upper end of the rotating cylinder 7 is attached to the upper end projection 33 of the support member 3. The lower end of the rotating cylinder 7 is attached to the rotating cylinder mounting part 23 of the lifting platform 2, which is located between the support member mounting part 21 and the horizontal holding member mounting part 22. When the rotating cylinder 7 extends or retracts, the lower end of the rotating cylinder 7 moves along the circle C in Figure 5. In this embodiment, the size of the rotating cylinder 7 is set so that the lifting platform 2 is in an upright position when the rotating cylinder 7 is most retracted.

[0032] Figure 7 is an enlarged view of area E in Figure 6. Figure 8 is a cross-sectional view along the FF line in Figure 7. As shown in Figures 6 and 7, the guide section 4 that guides the support member 3 to move up and down includes an extendable slide rail 5 and a grounding guide section 6. The slide rail 5 has a lower slide member 51 fixed to the mounting column 114 of the cargo box 110, an intermediate slide member 52 that can move up and down relative to the lower slide member 51, and an upper slide member 53 that can move up and down relative to the lower slide member 51 and the intermediate slide member 52. As shown in Figure 8, the lower slide member 51 and the upper slide member 53 have an I-shaped cross-section. The lower slide member 51 and the upper slide member 53 are long, plate-like and have almost the same shape.

[0033] The intermediate slide member 52 has an H-shaped cross-section. The length of the intermediate slide member 52 is the same as that of the lower slide member 51 and the upper slide member 53. The lower slide member 51 is fitted into a recess formed on the back surface of the intermediate slide member 52 (the surface facing the inner side wall of the cargo box 110). The upper slide member 53 is fitted into a recess formed on the front surface of the intermediate slide member 52. A steel ball 54 is interposed between the intermediate slide member 52 and the lower slide member 51. Similarly, a steel ball 54 is interposed between the intermediate slide member 52 and the upper slide member 53.

[0034] Figure 9 is a side view of the main part of the lifting device 1 showing the lifting platform 2 in the ground position. Figure 11 is a side view of the main part of the lifting device 1 showing the lifting platform 2 in the ceiling position. As shown in Figures 6 and 9, when the lifting platform 2 is at the cargo box floor position or the ground position, the slide rail 5 is in its most retracted state. In the most retracted state of the slide rail 5, the lower slide member 51, the intermediate slide member 52, and the upper slide member 53 overlap from the lower end to the upper end when viewed from the left-right direction (vehicle width direction). In this state, the downward movement of the intermediate slide member 52 relative to the lower slide member 51 is restricted within the slide rail 5. Also, the downward movement of the upper slide member 53 relative to the intermediate slide member 52 is restricted within the slide rail 5. That is, the upper slide member 53 and the intermediate slide member 52 set the lower end of the lower slide member 51 to its lower limit position.

[0035] On the other hand, as shown in Figure 11, when the lifting platform 2 is at the ceiling position, the slide rail 5 is in its most extended state. In the most extended state of the slide rail 5, the upper part of the lower slide member 51 and the lower part of the intermediate slide member 52 overlap, and the upper part of the intermediate slide member 52 and the lower part of the upper slide member 53 overlap. In this state, the upward movement of the intermediate slide member 52 relative to the lower slide member 51 is restricted within the slide rail 5. Also, the upward movement of the upper slide member 53 relative to the intermediate slide member 52 is restricted within the slide rail 5. As described above, the slide rail 5 expands and contracts between its most retracted state and its most extended state. As a result, the upper end of the upper slide member 53 of the slide rail 5 is configured to move up and down between the inside of the cargo box 110 and the top of the ceiling wall 113 of the cargo box 110.

[0036] The grounding guide section 6 is attached to the upper slide member 53 so as to position the upper end of the upper slide member 53 at the upper limit of the support member 3's upward movement and to guide the support member 3 so as to be able to move up and down. Specifically, the grounding guide section 6 has a plurality of guide rollers 64 attached to the support member 3 and a guide groove 62 provided in the upper slide member 53 into which the guide rollers 64 are fitted.

[0037] As shown in Figure 4, multiple guide rollers 64 are mounted on the support member 3 in a straight line in the vertical direction. Two guide rollers 64 are mounted at three locations: the upper end of the support member 3, the lower end, and slightly below the midpoint between the upper and lower parts of the support member 3. In addition, one guide roller 64 is mounted between the midpoint slightly below the midpoint of the support member 3 and the lower end of the support member 3. As shown in Figure 8, these guide rollers 64 are mounted on the support member 3 so as to face the upper slide member 53. Each guide roller 64 is fixed using roller mounting screws 65 and spacers 66.

[0038] The guide groove 62 is formed from the lower end to the upper end of the upper slide member 53. The guide groove 62 is linear in the vertical direction. The guide groove 62 is formed by a first guide groove member 61A and a second guide groove member 61B, which are linear plate members. The first guide groove member 61A and the second guide groove member 61B are each fixed to the upper slide member 53. A slit with a width approximately equal to the diameter of the guide roller 64 is provided between the first guide groove member 61A and the second guide groove member 61B. This slit becomes the guide groove 62.

[0039] A first retaining plate 63A is attached to the first guide groove member 61A. A second retaining plate 63B is attached to the second guide groove member 61B. A retaining slit is formed between the first retaining plate 63A and the second retaining plate 63B. The retaining slit is formed in a straight line along the guide groove 62. However, the width of the retaining slit is set to be slightly smaller than the diameter of the guide roller 64. This prevents the guide roller 64, which is fitted into the guide groove 62, from falling out of the guide groove 62.

[0040] As shown in Figure 7, the upper end of the guide groove 62 is blocked by a movement restricting member 67. The movement restricting member 67 is a rectangular plate. The movement restricting member 67 is attached to the upper end surfaces of the first guide groove member 61A and the second guide groove member 61B by a restricting member mounting screw 68. As the support member 3 is raised relative to the upper slide member 53 (guide groove 62), the uppermost guide roller 64 among the multiple guide rollers 64 attached to the support member 3 comes into contact with the movement restricting member 67. When the uppermost guide roller 64 attached to the support member 3 comes into contact with the movement restricting member 67, the support member 3 can no longer be raised relative to the upper slide member 53.

[0041] Unlike its upper end, the lower end of the guide groove 62 opens downwards. Therefore, as shown in Figure 9, when the support member 3 is lowered relative to the upper slide member 53 (guide groove 62), the lower guide roller 64 of the support member 3 disengages from the guide groove 62. In this embodiment, a total of seven guide rollers 64 are attached to the support member 3. When the lifting platform 2 is in the ground position, three of the seven guide rollers 64 are configured to disengage from the guide groove 62. In this state, the four guide rollers 64 restrict the support member 3 from tilting in the front-rear direction. Also, in this state, the guide rollers 64 are positioned at the lower end of the upper slide member 53 (guide groove 62). Therefore, the support member 3 is effectively restricted from tilting in the front-rear direction. With the above configuration, the grounding guide section 6 is configured to guide the support member 3 so that it can move up and down between the inside of the cargo box 110 and the ground G.

[0042] Figure 10 is a side view of the main part of the lifting power transmission mechanism 9, showing the rotating body 93 and its surroundings. As shown in Figures 6 and 10, the lifting power transmission mechanism 9 includes a lifting cylinder 91, a rotating body 93 consisting of a sprocket, and a winding transmission body 94 consisting of a chain. A pair of lifting power transmission mechanisms 9 are provided on the left and right sides of the lifting platform 2. The lifting cylinder 91 has a cylinder tube 91a fixed to the inner side wall of the cargo box 110 so as to be in the direction of extension and retraction of the slide rail 5, and a cylinder rod 91b that can move up and down relative to the cylinder tube 91a. The lifting cylinder 91 is located on the vehicle front side of the slide rail 5.

[0043] The rotating body 93, which consists of a sprocket, is attached to the tip of the cylinder rod 91b via a first mounting member 92. The first mounting member 92 is a U-shaped member that supports both ends of the rotation axis of the rotating body 93. The first mounting member 92 supports the rotating body 93 so that it can rotate freely around its horizontal axis (around the axis in the vehicle width direction).

[0044] The chain-wrapped transmission unit 94 is wrapped around the rotating body 93. One end of the chain-wrapped transmission unit 94 is attached to the transmission unit mounting portion 32 of the support member 3. The other end of the chain-wrapped transmission unit 94 is fixed to the fixing portion 97 of the cargo box 110. The fixing portion 97 is located at the upper end of the cylinder tube 91a. The fixing portion 97 is located on the vehicle front side of the rotating body 93. The transmission unit mounting portion 32 is located on the vehicle rear side of the rotating body 93. The chain-wrapped transmission unit 94 extends upward from the fixing portion 97 and is folded back by being wrapped around the rotating body 93. Then, the chain-wrapped transmission unit 94 extends downward from the rotating body 93 and connects to the transmission unit mounting portion 32.

[0045] As shown in Figures 1 to 3, the ceiling wall 113 of the cargo box 110 is provided with rectangular openings 113a at positions opposite to the rotating body 93 and guide section 4 of the lifting power transmission mechanism 9. Since the lifting power transmission mechanism 9 and guide section 4 are provided in pairs on the left and right sides of the cargo box 110, there are pairs of openings 113a on the left and right sides of the ceiling wall 113 of the cargo box 110. A ceiling cover 8 is attached to each opening 113a so as to be able to open and close the opening 113a. The ceiling cover 8 is part of the lifting device 1. The ceiling cover 8 has a hinge section (not shown) on the front edge of the opening 113a on the vehicle side. The ceiling cover 8 is rotatable vertically around this hinge section (direction of arrow A in Figure 2).

[0046] As shown in Figure 11, when the lifting platform 2 is at the ceiling position, the lifting cylinder 91 extends to its maximum extent. At this ceiling position of the lifting platform 2, the rotating body 93 at the tip of the cylinder rod 91b passes through the opening 113a from inside the cargo box 110 and reaches a position above the ceiling wall 113. Also at the ceiling position of the lifting platform 2, the upper end of the upper sliding member 53 of the slide rail 5 passes through the opening 113a from inside the cargo box 110 and reaches a position above the ceiling wall 113. The height position of the upper end of the upper sliding member 53 is higher than the height position of the rotating body 93.

[0047] At the ceiling position of the lifting platform 2, the slide rail 5 extends to its maximum extent. That is, the intermediate slide member 52 rises relative to the lower slide member 51, and the upper slide member 53 rises relative to the intermediate slide member 52. The slide rail 5 itself does not have a mechanism for extension or retraction. The driving force for extending the slide rail 5 is the upward force provided to the support member 3 by the lifting power transmission mechanism 9.

[0048] Figure 12 is an enlarged view of area H in Figure 11. As shown in Figures 11 and 12, when the lifting cylinder 91 of the lifting power transmission mechanism 9 extends, the winding transmission body 94 pulls up the transmission body mounting portion 32 of the support member 3. This causes the support member 3 to rise. As the winding transmission body 94 raises the support member 3 relative to the upper slide member 53 (guide groove 62), the uppermost guide roller 64 among the multiple guide rollers 64 attached to the support member 3 comes into contact with the movement restricting member 67. As the winding transmission body 94 raises the support member 3 further, with the guide roller 64 engaged with the movement restricting member 67, the support member 3 pulls the upper slide member 53 upward. When the upper slide member 53 is pulled upward, it rises from the fully retracted state of the slide rail 5 to the upper limit position of the upper slide member 53 relative to the intermediate slide member 52. When the support member 3 is raised further from the upper slide member 53's upper limit relative to the intermediate slide member 52, the upper slide member 53 pulls up the intermediate slide member 52. This action extends the slide rail 5.

[0049] When the lifting platform 2 is at the ceiling position, the upper end of the upper sliding member 53 is above the ceiling wall 113. When the lifting platform 2 is at the ceiling position, the support member 3 is above the ceiling wall 113 from its upper end to near its lower end.

[0050] The ceiling cover 8 is configured to open to a position where it does not contact the upper sliding member 53 when the rotating body 93 and the upper sliding member 53 pass through the opening 113a and are positioned above the ceiling wall 113. Furthermore, the ceiling cover 8 is configured to close by covering the upper sliding member 53 when the upper sliding member 53 is located inside the cargo box 110. In this embodiment, no dedicated actuator is provided for opening and closing the ceiling cover 8. The driving force of the lifting cylinder 91 of the lifting power transmission mechanism 9 is used for opening and closing the ceiling cover 8.

[0051] Let me explain in detail. The rotating body 93 is configured to move to a position where it protrudes above the ceiling wall 113 from the opening 113a when the upper sliding member 53 has risen to its upper limit position. This is utilized. As shown in Figures 2, 10, and 11, the rotating body 93 is attached to the tip of the cylinder rod 91b of the lifting cylinder 91 via a first mounting member 92. A plate-shaped second mounting member 95 is attached to this first mounting member 92. Two contact rollers 96 are attached to the second mounting member 95 for contacting the lower surface of the ceiling wall 113. The contact rollers 96 are configured to contact the ceiling wall 113 and push up the ceiling cover 8 when the upper sliding member 53 rises, before the upper sliding member 53 and the rotating body 93 interfere with the ceiling wall 113.

[0052] Figure 13 is a hydraulic circuit diagram of the lifting device 1 of this embodiment. As shown in Figure 13, the lifting device 1 includes a hydraulic pump 191, an electric motor 192 that drives the hydraulic pump 191, a hydraulic oil tank 193, a pair of lifting cylinders 91 and a pair of rotating cylinders 7 that are driven by the hydraulic oil supplied from the hydraulic pump 191, and a control valve unit 194 for controlling the extension and retraction of the lifting cylinders 91 and the rotating cylinders 7.

[0053] A main supply channel 199a and a main return channel 199b are connected between the hydraulic oil tank 193 and the control valve unit 194. A hydraulic pump 191 is located in the middle of the main supply channel 199a. A lifting cylinder head side channel 199c and a lifting cylinder rod side channel 199d are connected between the lifting cylinder 91 and the control valve unit 194.

[0054] The lifting cylinder head side passage 199c extends from the control valve unit 194 in a single passage, and then splits into two passages through the flow divider valve 195. The lifting cylinder head side passage 199c is then connected to the cylinder head chamber of the lifting cylinder 91. The flow divider valve 195 ensures that hydraulic fluid is supplied evenly to the cylinder head chambers of the pair of lifting cylinders 91. This configuration ensures that the operation of extending the lifting cylinders 91 and raising the lifting platform 2 is smooth. In addition, a pilot check valve 198 is provided between the lifting cylinder 91 and the flow divider valve 195 in the lifting cylinder head side passage 199c.

[0055] The lifting cylinder rod side flow path 199d is formed when the flow paths extending from the cylinder rod chambers of the pair of lifting cylinders 91 merge into a single flow path, and then connect to the control valve unit 194. A first flow control valve 196 is provided in the middle of the lifting cylinder rod side flow path 199d. This first flow control valve 196 adjusts the contraction speed of the lifting cylinder 91. In other words, the first flow control valve 196 adjusts the descent speed of the lifting platform 2.

[0056] Furthermore, in the lifting cylinder rod side flow path 199d, a pilot flow path 199g is branched off between the first flow control valve 196 and the control valve unit 194. The pilot flow path 199g is connected to the pilot check valve 198. The pilot flow path 199g and the pilot check valve 198 ensure that the pilot check valve 198 opens only when the control valve unit 194 switches to controlling the retraction operation of the lifting cylinder 91. This allows the pilot check valve 198 to suppress unintended retraction of the lifting cylinder 91. In other words, the pilot check valve 198 can suppress unintended lowering of the lifting platform 2.

[0057] Furthermore, a rotating cylinder head-side passage 199e and a rotating cylinder rod-side passage 199f are connected between the rotating cylinder 7 and the control valve unit 194. A second flow rate control valve 197 is provided in the middle of the rotating cylinder rod-side passage 199f. This second flow rate control valve 197 adjusts the extension speed of the rotating cylinder 7. In other words, the second flow rate control valve 197 adjusts the downward rotation speed of the lifting platform 2.

[0058] As described above, the lifting device 1 according to this embodiment comprises a lifting platform 2 on which transported goods are placed, a support member 3 that supports the lifting platform 2 so as to be able to rotate up and down, a guide section 4 that guides the support member 3 so as to be able to move up and down, and a lifting power transmission mechanism 9 that transmits a driving force for lifting to the support member 3. The guide section 4 includes an extendable slide rail 5 and a grounding guide section 6. The slide rail 5 has a lower slide member 51 whose lower end is fixed to the lower part of the cargo box 110, and an upper slide member 53 that sets the position of the lower end of the lower slide member 51 to its lower limit position and is able to move up and down relative to the lower slide member 51. The upper end of the upper slide member 53 is configured to move up and down between the inside of the cargo box 110 and above the ceiling wall 113 of the cargo box 110. The grounding guide section 6 is attached to the upper slide member 53 so as to set the position of the upper end of the upper slide member 53 to the upper limit position of the support member 3 and to guide the support member 3 so as to be able to move up and down. The grounding guide section 6 is configured to guide the support member 3 so that it can move up and down between the inside of the cargo box 110 and the ground G.

[0059] According to the above configuration, the guide section 4 that guides the support member 3 of the lifting platform 2 to move up and down is composed of a slide rail 5 that does not move below the lower part of the cargo box 110 and a grounding guide section 6. The upper slide member 53 of the slide rail 5 and the grounding guide section 6 guide the support member 3 from inside the cargo box 110 to above the ceiling wall 113 of the cargo box 110. In addition, only the grounding guide section 6 of the guide section 4 guides the support member 3 to move up and down between the inside of the cargo box 110 and the ground G. As a result, the support member 3 is guided by the guide section 4 from the ground G to a position above the ceiling wall 113 of the cargo box 110. With this guide structure, compared to conventional lifting devices in which many parts were provided inside the outer column, each part of the support member 3 and the guide section 4 can be exposed when viewed from inside the cargo box 110. As a result, the lifting device 1 has excellent maintainability as it is easier for workers to determine the condition of each part during maintenance.

[0060] Furthermore, when the vehicle is in motion, the lifting platform 2 is retracted so that its base is positioned below the cargo box 110, thereby maintaining the slide rail 5 in its most contracted state. This allows the lifting power transmission mechanism 9 to be subjected to the weight of the support member 3 while the weight of the slide rail 5 is not applied during vehicle operation. As a result, the load on the lifting power transmission mechanism 9 can be reduced compared to conventional lifting devices that required maintaining the height positions of the intermediate column and slider during vehicle operation. Consequently, the lifting device 1 is less prone to malfunction.

[0061] Furthermore, the lifting device 1 of this embodiment includes a ceiling cover 8 that can be opened and closed and attached to the opening 113a of the ceiling wall 113 of the cargo box 110. The ceiling cover 8 is configured to open to a position where it does not come into contact with the upper sliding member 53 when the upper sliding member 53 has passed through the opening 113a and is located above the ceiling wall 113. The ceiling cover 8 is configured to close to cover the upper sliding member 53 when the upper sliding member 53 is located inside the cargo box 110.

[0062] With the above configuration, when the vehicle is in motion, the ceiling cover 8 covers the upper part of the upper sliding member 53, thereby preventing the slide rail 5, the grounding guide portion 6, and the support member 3 from being exposed to wind and rain. Furthermore, since the ceiling cover 8 is configured to open in a position that does not come into contact with the upper sliding member 53, the slide rail 5, including the upper sliding member 53, will not be damaged by opening and closing the ceiling cover 8. As a result, malfunctions are even less likely to occur.

[0063] Furthermore, in this embodiment, the lifting power transmission mechanism 9 includes a lifting cylinder 91 having a cylinder tube 91a fixed to the cargo box 110 along the extension and retraction direction of the slide rail 5 and a cylinder rod 91b that can move up and down relative to the cylinder tube 91a; a rotating body 93 attached to the tip of the cylinder rod 91b via a first mounting member 92 and a second mounting member 95 and rotatable around a horizontal axis; and a winding transmission body 94 wrapped around the rotating body 93, with one end attached to the support member 3 and the other end fixed to the fixing part 97 of the cargo box 110. With this configuration, the support member 3 can be raised and lowered with a simple configuration.

[0064] Furthermore, in this embodiment, the rotating body 93 is configured to move to a position where it protrudes above the ceiling wall 113 from the opening 113a when the upper sliding member 53 rises to its upper limit position. A contact roller 96 is attached to the second mounting member 95 for contacting the lower surface of the ceiling wall 113. The contact roller 96 is configured to contact the ceiling cover 8 and push up the ceiling cover 8 before the upper sliding member 53 and the rotating body 93 interfere with the ceiling wall 113 when the upper sliding member 53 rises.

[0065] According to the above configuration, the driving force to extend the lifting cylinder 91 is transmitted to the ceiling cover 8 via the first mounting member 92, the second mounting member 95, and the contact roller 96. This eliminates the need to provide a separate actuator for opening and closing the ceiling cover 8, thus simplifying the structure of the lifting device 1. In addition, the contact roller 96 prevents the ceiling cover 8 from hitting the upper sliding member 53 and the rotating body 93, thereby suppressing failures of the lifting power transmission mechanism 9 and the guide section 4.

[0066] The embodiments disclosed herein are illustrative in all respects and are not intended to be restrictive. The technical scope of the present invention is not construed solely by the embodiments described above, but is defined by the claims. Furthermore, the technical scope of the present invention includes all modifications within the meaning and scope of equivalents to the claims.

[0067] For example, in the above embodiment, the winding transmission 94 consisted of a chain, and the rotating body 93 consisted of a sprocket. The present invention is not limited to this. A wire may be used as the winding transmission, and a sheave may be used as the rotating body.

[0068] Furthermore, in the above embodiment, the slide rail 5 was configured such that a total of three members—a lower slide member 51, an intermediate slide member 52, and an upper slide member 53—could move up and down relative to each other. The present invention is not limited to this. For example, the slide rail may have multiple intermediate slide members. Alternatively, the slide rail may have only a lower slide member and an upper slide member, without any intermediate slide members. [Explanation of Symbols]

[0069] 1. Lifting device 2 Elevator 3. Support member 4 Guide section 5 slide rails 6. Grounding guide section 8 Ceiling cover 9. Lifting power transmission mechanism 51 Lower sliding member 52 Intermediate sliding member 53 Upper sliding member 62 Guide grooves 64 Guide Rollers 91 Lifting Cylinder 91a Cylinder tube 91b Cylinder rod 92 First mounting member 93. Solids of revolution 94. Winding transmission 95 Second mounting member 96 Contact roller 97 Fixed part 100 work vehicles 110 Packing box 113 Ceiling and Wall 113a opening G Ground

Claims

1. A work vehicle equipped with a lifting device having a lifting platform on which transported goods are placed, a support member that supports the lifting platform so as to be able to rotate up and down, a guide part that guides the support member so as to be able to move up and down, and a lifting power transmission mechanism that transmits a driving force for lifting to the support member, The guide section includes an extendable slide rail and a grounding guide section. The slide rail comprises a lower slide member whose lower end is fixed to the lower part of the vehicle's cargo box, and an upper slide member whose lower end is positioned at the lower limit of the lower slide member and which is vertically movable relative to the lower slide member. The upper end of the upper sliding member is configured to move up and down between the inside of the vehicle cargo box and above the ceiling wall of the vehicle cargo box. The grounding guide portion is attached to the upper slide member so as to position the upper end of the upper slide member at the upper limit position of the support member and to guide the support member so as to be able to move up and down. The grounding guide portion is configured to guide the support member so that it can move up and down between the inside of the vehicle's cargo box and the ground. A work vehicle characterized by the following features.

2. The vehicle's cargo box is further equipped with a ceiling cover that can be opened and closed and attached to the opening in the ceiling wall of the vehicle's cargo box, The ceiling cover is configured to open to a position where it does not come into contact with the upper sliding member when the upper sliding member passes through the opening and is positioned above the ceiling wall. The ceiling cover is configured to cover and close the upper part of the upper sliding member when the upper sliding member is located inside the vehicle's cargo box. The work vehicle according to feature 1.

3. The aforementioned lifting power transmission mechanism is A lifting cylinder having a cylinder tube fixed to the vehicle cargo box so as to be aligned with the extension and retraction direction of the slide rail, and a cylinder rod that is movable up and down relative to the cylinder tube, A rotating body is attached to the tip of the cylinder rod via a mounting member and is rotatable around a horizontal axis, The system includes a winding transmission body that is wrapped around the rotating body, with one end attached to the support member and the other end fixed to the fixing part of the vehicle's cargo box, The work vehicle according to feature 2.

4. The rotating body is configured to move to a position where it protrudes above the ceiling wall from the opening when the upper sliding member is raised to its upper limit position. The mounting member is fitted with a contact roller for contacting the lower surface of the ceiling wall. The contact roller is configured to contact the ceiling cover and push up the ceiling cover before the upper sliding member and the rotating body interfere with the ceiling wall when the upper sliding member rises. The work vehicle according to feature 3.

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