Lifting device

Abstract

To a lifting device capable of changing the maximum loading weight and an elevation height by a partial component change, capable of performing a maintenance without causing oil leakages due to a long-term deterioration, etc., and capable of being manufactured at low cost without using hydraulic or water pressure.SOLUTION: A lifting device has: a driving unit consisting of a driving shaft, a driving motor, a pinion gear, a roller shaft arranged in one of vertical directions with respect to the driving shaft, an upper roller and a lower roller incorporated in the driving shaft and the roller shaft, and a shaft fixing plate; a rack post and a guide post for clamping the upper roller and the lower roller; a table frame fixed to the shaft fixing plate; and a table member fixed to the table frame. The lifting device is provided so that a rack is formed on the rack post, the pinion gear rotates while meshing with the rack by the driving motor, and the table member fixed to the table frame is raised and lowered as the upper roller and the lower roller are raised and lowered along the rack post and the guide post.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a lifting device for lifting and lowering a load. [Background technology]

[0002] Conventionally, as a lifting device used for lifting and unloading cargo, etc., a lifting device is known in which a rack and a pinion gear are meshed and a loading platform is raised and lowered by rotating the pinion gear with a drive motor, as shown in the following patent document.

[0003] Other known lifting devices include hydraulic cylinder type and water pressure cylinder type, which move a piston in a cylinder and raise or lower a load by the generated pressure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-135695 Summary of the Invention [Problem to be solved by the invention]

[0005] The maximum load weight and maximum height limit for each lifting device differ depending on the purpose of use, and when designed, the structure and components are determined so that it can lift and lower loads up to the specified load weight. In other words, a lifting device cannot lift or lower loads that exceed the specified maximum load weight, and if you want to lift or lower a load that exceeds the specified maximum load weight for that lifting device, a fundamental design change is required.

[0006] In particular, hydraulic cylinder and water pressure cylinder lifting devices require a large number of parts, such as pumps, valves, tanks, and piping, in addition to the cylinder, resulting in a problem of high manufacturing costs.

[0007] Furthermore, hydraulic cylinder and water pressure cylinder type lifting devices tend to leak oil or water due to deterioration over time, making maintenance of these devices a complicated task for workers.

[0008] The present invention has been proposed to address these circumstances, and aims to provide a lifting device that allows the maximum load capacity and lifting height to be easily changed by simply changing some parts, that allows for easy maintenance without causing oil or water leaks due to aging or other factors, and that can be manufactured inexpensively without using hydraulic or water pressure in its configuration. [Means for solving the problem]

[0009] In order to solve such problems, the lifting device according to the present invention is an elevator having a drive unit including a drive motor connected to a drive shaft and rotating the drive shaft, a pinion gear fixed to the drive shaft, a roller shaft disposed either above or below the drive shaft in the vertical direction, upper and lower rollers incorporated into the drive shaft and the roller shaft, and a shaft fixing plate supporting the drive motor, the drive shaft, and the roller shaft, a rack support and a guide support attached to a main frame and sandwiching the upper and lower rollers, a table frame fixed to the shaft fixing plate, and a table member fixed to the table frame and having a loading surface on which loads are placed. The lowering device is characterized in that a rack that meshes with the pinion gear is formed along the longitudinal direction on the rack support, the outer diameters of the upper roller and the lower roller are such that the rack and the pinion gear can mesh properly when the upper roller and the lower roller are clamped between the rack support and the guide support, and the pinion gear fixed to the drive shaft rotates while meshing with the rack when driven by the drive motor, and the upper roller and the lower roller rise and fall along the rack support and the guide support, thereby raising and lowering a table frame fixed to the shaft fixing plate and raising and lowering a table member fixed to the table frame. [Effects of the Invention]

[0010] Due to these characteristics, the lifting device of the present invention makes it possible to easily change the maximum load weight and lifting height by simply changing some of the parts, and also makes it possible to easily perform maintenance without causing oil or water leaks due to deterioration over time, and to manufacture it inexpensively without using hydraulics or water pressure in its structure. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a front view of a lifting device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a top view of a main frame of the lifting device according to the embodiment of the present invention. [Figure 3] FIG. 2 is a side view of a drive unit of the lifting device according to the embodiment of the present invention. [Figure 4] FIG. 2 is a cross-sectional top view of a drive unit of the lifting device according to the embodiment of the present invention. [Figure 5] FIG. 2 is a top view of a table frame of the lifting device according to the embodiment of the present invention. [Figure 6] FIG. 2 is a top view of a table member of the lifting device according to the embodiment of the present invention. [Figure 7] 1A and 1B are diagrams illustrating an example of an operation of the lifting device according to the embodiment of the present invention; [Figure 8] 10 is a diagram showing the state where the platform of the lifting device according to the embodiment of the present invention is installed on uneven ground. FIG. [Figure 9] 4 is an example of a moment acting on the lifting device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same reference numerals denote parts having the same functions, and duplicated descriptions in the drawings will be omitted as appropriate.

[0013] [Configuration of lifting device 1] 1 to 6 show the configuration of a lifting device 1 according to an embodiment of the present invention. As shown in Fig. 1, the lifting device 1 is made up of a main frame 10, rack support columns 20, guide support columns 30, a drive unit 40, a table frame 80, and a table member 90. In Fig. 1, the rack 21, lower rollers 50, upper rollers 60, etc., which are hidden by a shaft fixing plate 70 of the drive unit 40, are shown by dashed lines. The lifting device 1 is a device for lifting and lowering a table member 90 on which a load such as cargo is placed, for example, to lift and unload heavy objects that are difficult to lift and unload manually.

[0014] [Mainframe 10] As shown in FIG. 2, the main frame 10 is U-shaped, enclosed on three sides and open on one side (the X direction in the figure). In the following description, the direction toward the open side of the U-shape (the X direction in the figure) is referred to as the front direction, the direction opposite the open side (the direction opposite the X direction in the figure) is referred to as the rear direction, and the remaining two sides (the Y direction in the figure and the direction opposite the Y direction) are referred to as the left and right directions. Of the three sides of the U-shaped main frame 10, two sides parallel to the X direction in the figure are provided with mounting plates 13 for mounting rack posts 20 and guide posts 30, which will be described later. The mounting plates 13 are provided near the center of each of the two sides in the longitudinal direction. In addition, wheels 14 are provided at both ends of each of the two sides parallel to the X direction in the figure (see FIG. 1), making the main frame 10 a movable frame. When the lifting device 1 is used to lift or lower a load, the wheels 14 are locked by wheel stoppers (not shown).

[0015] Of the three sides of the U-shaped main frame 10, one side parallel to the Y direction in the figure, which faces the opening, can be separated at the center section 12A. In other words, the U-shaped main frame 10 is formed by connecting two L-shaped frames. Because the main frame 10 can be separated at the center section 12A into two L-shaped frames, the rack support 20, guide support 30, drive unit 40, and table frame 80 can be assembled separately for each of the two L-shaped frames, making the assembly of the lifting device 1 easier than with a main frame that is not separated.

[0016] Furthermore, the main frame 10 formed by connecting two L-shaped frames is less expensive than a non-separable main frame 10, and the use of a separable main frame 10 can reduce the manufacturing cost of the lifting device 1.

[0017] In the following description, of the three sides of the main frame 10, the two sides parallel to the X direction in the drawing on which the mounting plates 13 are provided are referred to as parallel sides 11, and the side parallel to the Y direction in the drawing, which can be divided at the center portion 12A, is referred to as divided side 12. Furthermore, the rack support posts 20, guide support posts 30, drive unit 40, etc. are provided on each of the two parallel sides 11, but unless otherwise specified, only one of them will be described below.

[0018] [Rack support 20 and guide support 30] As shown in FIG. 1 , the rack pillar 20 and the guide pillar 30 are attached to the mounting plate 13 of the main frame 10 side by side along the longitudinal direction of the parallel side 11 so that the longitudinal direction of the pillars is the vertical direction (the Z direction in the figure). A rack 21 is formed on the rack pillar 20 and extends along the longitudinal direction of the rack pillar 20, and a pinion gear 51 fixed to a drive shaft 71 (described later) meshes with the rack 21 of the rack pillar 20 to form a so-called rack and pinion. The meshing between the rack 21 and the pinion gear 51 will be described later. A lower roller 50 and an upper roller 60 positioned vertically above the lower roller 50 are provided between the rack pillar 20 and the guide pillar 30, and the guide pillar 30 is attached to the mounting plate 13 of the main frame 10 with the lower roller 50 and upper roller 60 sandwiched between the rack pillar 20 and the guide pillar 30. The rack support 20 is attached to the mounting plate 13 of the main frame 10 so that the rack 21 formed on the rack support 20 faces the guide support 30 .

[0019] Furthermore, the rack posts 20 and guide posts 30 attached to each of the two mounting plates 13 are attached so as to be symmetrical in the left-right direction for each of the two mounting plates 13. That is, when viewed from the opening side of the U-shaped main frame 10, if the rack post 20 is attached to the back side of the right mounting plate 13 and the guide post 30 is attached to the front side, then the rack post 20 is also attached to the back side of the left mounting plate 13 and the guide post 30 is attached to the front side.

[0020] The rack support 20 and the guide support 30 are fixed at the bottom by screwing them to the mounting plate 13 of the main frame 10, and at the top they are fixed to each other by screwing the guide upper plate 32 of the guide support 30 to the rack upper plate 22 extending from the rack support 20 toward the guide support 30.

[0021] Furthermore, the rack support 20 and the guide support 30 are attached so as to be positioned approximately at the center of the width in the front-to-rear direction (X direction in the figures) of the loading surface 91 of the table member 90, which will be described later. To be precise, it is desirable to position the rack support 20 and the guide support 30 so that the shaft centers 50C and 60C (see FIGS. 3 and 4) of the lower roller 50 and the upper roller 60, which are sandwiched between the rack support 20 and the guide support 30, are approximately at the center of the width in the front-to-rear direction (X direction in the figures) of the loading surface 91. By positioning the rack support 20 and the guide support 30 in this manner, the balance is best for the moment when an object is placed on the loading surface 91 of the table member 90, and the durability of the lifting device 1 can be improved. A specific explanation of the moment will be given later.

[0022] [Drive unit 40] The drive unit 40 will be described using Figures 3 and 4. Figure 3 is a side view of the drive unit 40, and Figure 4 is a top view of a cross section of the drive unit 40 taken at the height of the shaft center 50C in the illustrated Z direction of the lower roller 50 in the side view of the drive unit 40 in Figure 3. The drive unit 40 is made up of a drive motor 41, a drive shaft 71, a roller shaft 72, a lower roller 50, an upper roller 60, and two shaft fixing plates 70.

[0023] A power source is connected to the drive motor 41, which drives a motor (not shown) inside the drive motor 41 to rotate the drive shaft 71. One end of the drive shaft 71 is connected to a motor inside the drive motor 41, and the other end protrudes from the drive motor 41. A pinion gear 51 is fixed to the portion of the drive shaft 71 that protrudes from the drive motor 41, and when the drive motor 41 is driven to rotate the drive shaft 71, the pinion gear 51 rotates integrally with the drive shaft 71.

[0024] The lower roller 50 and the upper roller 60 are cylindrical in shape, axially penetrating the center of the bottom surface, and two rollers are provided on each of the drive shaft 71 and the roller shaft 72, which is disposed vertically above the drive shaft 71. The lower roller 50 and the upper roller 60 are disposed vertically one above the other, with the outer diameter 50A of the lower roller 50 and the outer diameter 60A of the upper roller 60 sandwiched between the rack support 20 and the guide support 30.

[0025] 4, the two lower rollers 50 and the two upper rollers 60 are respectively provided on the drive shaft 71 and the roller shaft 72 so that a width B between the ends of the lower rollers 50 and the upper rollers 60 opposite to the side where the other lower roller 50 and upper roller 60 are provided is wider than a width A of the rack support 20 and the guide support 30 in the axial direction (the Y direction in the figure), and the lower rollers 50 and the upper rollers 60 have flanges 52 formed at one end in the axial direction. The two lower rollers 50 and the two upper rollers 60 are provided on the drive shaft 71 and the roller shaft 72 so that the flanges 52 face away from the other lower roller 50 and upper roller 60. When the rack support 20 and the guide support 30 sandwich the lower rollers 50 and the upper roller 60, the rack support 20 and the guide support 30 fit between the flanges 52 of the two lower rollers 50 and the upper rollers 60. The flanges 52 come into contact with the rack support 20 and the guide support 30, thereby preventing the lower roller 50 and the upper roller 60 from being displaced in the axial direction (Y direction in the drawing).

[0026] The pinion gear 51 that meshes with the rack 21 formed on the rack support 20 is fixed to the drive shaft 71, and the lower rollers 50 are provided on both sides of the pinion gear 51 in the Y direction in the figure. Because the rack support 20 and the guide support 30 sandwich the outer diameter 50A of the lower roller 50, the degree of meshing between the rack 21 and the pinion gear 51 is determined by the size of the outer diameter 50A of the lower roller 50. The outer diameter 50A is set to a size that allows the rack 21 and pinion gear 51 to mesh appropriately.

[0027] As shown in FIG. 3 , the shaft fixing plates 70 are disposed on both sides of the lower roller 50 and the upper roller 60 in the axial direction (the Y direction in the figure). The drive shaft 71 passes through the shaft center 50C of the lower roller 50, and the roller shaft 72 passes through the shaft center 60C of the upper roller 60. The shaft fixing plate 70 supports the drive shaft 71 and the roller shaft 72. One end of the drive shaft 71 is supported by the shaft fixing plate 70, and the other end passes through the shaft fixing plate 70 and is connected to the drive motor 41. Because one end of the drive shaft 71 and the portion through which the shaft fixing plate 70 passes are supported by the shaft fixing plate 70, the drive motor 41, to which the other end of the drive shaft 71 is connected, is also indirectly supported by the shaft fixing plate 70 via the drive shaft 71. The roller shaft 72 is supported by the shaft fixing plate 70 at both ends. Because the drive shaft 71 is rotationally driven by the drive motor 41, the shaft fixing plate 70 supports one end of the drive shaft 71 so as not to interfere with the rotation of the drive shaft 71. On the other hand, the roller shaft 72 is fixed to the shaft fixing plate 70 so as not to rotate.

[0028] Furthermore, the shaft inner diameters 50B, 60B of the lower roller 50 and the upper roller 60 are not fixed to the drive shaft 71 and roller shaft 72, and when the drive motor 41 is driven to raise and lower the lower roller 50 and upper roller 60, they are arranged so that they can rotate freely relative to the drive shaft 71 and roller shaft 72 via the bearings 73.

[0029] The drive motor 41 is disposed outside the shaft fixing plate 70 in the left-right direction (Y direction in the figure). In other words, the drive motor 41 does not protrude toward the table member 90 side, but protrudes outward in the left-right direction (Y direction in the figure) relative to the table member 90. By disposing it in this manner, the drive motor 41 (drive unit 40) does not protrude toward the table member 90 side, and does not interfere with the loading and unloading of loads. Furthermore, because the drive motor 41 is provided on the outside, maintenance of the drive unit 40 including the drive motor 41 can be easily performed.

[0030] [Table Frame 80] As shown in FIG. 5, the table frame 80 is housed within the U-shaped main frame 10 in a plan view. The table frame 80 is composed of a vertical column member 81 (see FIG. 1), a frame member 82, and a horizontal column member 83. Specifically, the table frame 80 is composed of left and right vertical column members 81A and 81B that rise in the Z direction and are fixed to the shaft fixing plate 70 of the drive unit 40, left and right frame members 82A and 82B that are provided at the lower ends of the vertical column members 81A and 81B and extend in the X direction, and a horizontal column member 83 that extends in the Y direction between the frame members 82A and 82B and connects the two left and right frame members 82A and 82B. The vertical column member 81 is fixed to the shaft fixing plate 70 of the drive unit 40, and the table frame 80 rises and falls integrally with the shaft fixing plate 70 as the drive unit 40 rises and falls. A table member 90, which will be described later, is placed on and fixed to the horizontal column member 83.

[0031] The horizontal pillar member 83 extending in the Y direction in the drawing can be separated into horizontal pillar members 83A and 83B at the central portion 83C, similar to the dividing edge 12 of the main frame 10. Therefore, when assembling the lifting device 1, the table frame 80 can also be assembled in the same manner as the rack pillars 20, guide pillars 30, drive unit 40, etc.

[0032] The table frame 80, which is formed by connecting two frames like the main frame 10, is less expensive than a non-divisible table frame 80, and the use of a divisible table frame 80 can reduce the manufacturing cost of the lifting device 1.

[0033] [Table member 90] As shown in FIG. 6 , the table member 90 is composed of a loading surface 91, a boarding plate 92, a stopper plate 94, and a projection plate 93. The table member 90 is attached with the loading surface 91 fixed to the horizontal pillar member 83 of the table frame 80. An object to be raised or lowered by the lifting device 1 is placed on the loading surface 91 of the table member 90. The boarding plate 92 and the stopper plate 94 are provided at the front end of the loading surface 91, and the projection plate 93 is provided at the rear end. The loading surface 91, the boarding plate 92, the stopper plate 94, and the projection plate 93 are connected to the loading surface 91 via respective rotation shafts 92A, 93A, and 94A and bearing plates 95, and the boarding plate 92, the stopper plate 94, and the projection plate 93 can move up and down (in the Z direction and the opposite side to the Z direction in the figure) around the respective rotation shafts 92A, 93A, and 94A.

[0034] [Loading and unloading operations] 7(a) and 7(b), an example of the operation of the lifting device 1 when using the lifting device 1 to unload a load onto the bed of a truck T will be described. As shown in FIG. 7(a), the boarding plate 92 and the extending plate 93 move up and down (in the Z direction and the opposite side to the Z direction in the figure) around rotation shafts 92A and 93A. When placing a load on the table member 90 from the height of the ground G, as shown in FIG. 7(a), the table member 90 is lowered until the lower surface of the table frame 80 is at a height where it contacts the ground G, and the boarding plate 92 is extended forward. The boarding plate 92 and the extending plate 93 are thinner than the loading surface 91, and the boarding plate 92 is connected to the loading surface 91 via the rotation shaft 92A at the height of the upper surface of the loading surface 91, so that the boarding plate 92 is extended forward at a downward incline by the height of the loading surface 91 and the table frame 80.

[0035] Furthermore, as shown in Figure 8, even if the place where the load is to be placed is uneven ground, the boarding plate 92 can be extended by adjusting the height to suit the uneven ground. Figure 8 shows an example of the movement of the boarding plate 92 when a load that is lower than the contact surface between the table frame 80 and the ground G is to be placed on the loading surface 91. The boarding plate 92 is extended forward and inclined further downward than shown in Figure 7(a), and is extended so that the height of the tip of the boarding plate 92 is lower than the contact surface between the table frame 80 and the ground G. With the boarding plate 92 movable in this way, the load can be stably placed on the loading surface 91 even on uneven ground such as that shown in Figure 8.

[0036] After the load is loaded onto the loading surface 91 via the boarding plate 92, the boarding plate 92 is folded at about 90 degrees in the same manner as the boarding plate 93, as shown in FIG. 7(b), and the table member 90 is raised to match the height of the bed of the truck T. Once the table member 90 has been raised, the folded boarding plate 93 is extended onto the bed of the truck T, and the load is lowered from the loading surface 91 onto the bed of the truck T via the boarding plate 93. In this way, it is possible to lift heavy objects that are difficult to lift manually. Conversely, when unloading objects from the bed of the truck T onto the ground G, the procedure described above can be performed in reverse. When storing or moving the lifting device, the boarding plate 92 can be folded at about 90 degrees to make the lifting device more compact in the front-to-rear direction.

[0037] A stopper plate 94 is provided behind the boarding plate 92 and in front of the loading surface 91 to prevent the load from falling forward from the loading surface, further preventing the load from falling off. As shown in FIG. 7(b), the stopper plate 94 is connected to the loading surface 91 via a rotation shaft 94A and can move around the rotation shaft 94A. A switching arm 96 that rotates the rotation shaft 94A is attached to one end of the longitudinal direction (the Y direction in the figure) of the rotation shaft 94A (see FIG. 6). The switching arm 96 is attached so as to extend obliquely downward relative to the loading surface 91 when the table member 90 is raised above the ground surface G as shown in FIG. 7(b). The switching arm 96 is also provided with a spring member 97 that applies torque to the switching arm 96 by elastic force in a direction that causes the rotation shaft 94A to rise up and the stopper plate 94. One end of the spring member 97 is connected to the switching arm 96, and the other end is connected to the frame member 82. When the table member 90 is raised above the ground surface G as shown in FIG. 7(b), the elastic force of the spring member 97 acts on the switching arm 96 to rotate the rotation shaft 94A in a direction that raises the stopper plate 94. On the other hand, when the table member 90 descends, the switching arm 96 comes into contact with the ground surface G, and as the table member 90 descends, the switching arm 96 is pushed by the ground surface G from the state shown in FIG. 7(b) and rotates upward, and as the switching arm 96 rotates, the rotation shaft 94A rotates and the stopper plate 94 falls down. Then, when the table member 90 descends and is in contact with the ground surface G, the stopper plate 94 falls down completely and becomes flush with the loading surface 91 as shown in FIG. 7(a). When the table member 90 rises again above the ground surface G, the switching arm 96 rotates downward due to the elastic force of the spring member 97, the rotation shaft 94A rotates, and the stopper plate 94 rises up again. In this way, when a load is placed on the table member 90 on the ground surface G, the stopper plate 94 is flush with the loading surface and does not interfere with the loading, and when the table member 90 moves away from the ground surface G, it stands up to prevent the load from falling off.When the table member 90 is raised above the ground surface G as shown in Figure 7(b), the elastic force of the spring member 97 acts to rotate the rotation axis 94A of the switching arm 96 in the direction in which the stopper plate 94 rises, but a rotation stopper (not shown) is provided to prevent the force of the spring member 97 from rotating it beyond the state shown in Figure 7(b), for example.

[0038] The platform 93 is folded at about 90 degrees when a load is being loaded, and by restricting extension, the platform 93 is prevented from falling off. In the example shown, a handle 85 is provided on the table frame 80, and one end of a chain 86 is connected to the platform 93, with the other end fixed to the handle 85, thereby restricting extension of the platform 93. The example shown is merely an example, and other restricting means may be provided to restrict extension of the platform 93.

[0039] [About Moments] Using Figure 9, we will explain the moment when an object is placed on the loading surface 91 of the table member 90. In the example shown in Figure 9, the object is placed near the end of the loading surface 91 of the table member 90 in the X direction. At this time, the relationship between the moment and the force acting on the fulcrum can be expressed by the following equations (1) and (2). M=W*L1 (1) F=(W*L1) / L2 (2)

[0040] M is the moment that tends to rotate the table member 90 as shown by the arrow, W is the weight of the load, and L1 is the arm length from the fulcrum axis of the table member 90 to the center of gravity of the load. As shown in equation (1), the moment M that rotates the table member 90 depends on the weight W of the load and the arm length L1 from the fulcrum axis to the center of gravity of the load. Furthermore, F is the force acting on the fulcrum of the table member 90, and L2 is the distance between the two fulcrums (the lower roller 50 and the upper roller 60). As shown in equation (2), the longer the distance L2 between the two fulcrums (the lower roller 50 and the upper roller 60), the smaller the force F acting on the fulcrum. In the lifting device 1, the force F acting on the fulcrum is supported by the left and right rack supports 20 and guide supports 30, so the table member 90 does not rotate.

[0041] From equations (1) and (2), when the weight W of the load is fixed, in order to reduce the load on the lifting device 1 due to the moment, it is important to reduce the length L1 of the arm and to increase the distance L2 between the two fulcrums (the lower roller 50 and the upper roller 60).

[0042] As described above, it is desirable to arrange the lower roller 50 and the upper roller 60 sandwiched between the rack support 20 and the guide support 30 so that their centers are approximately at the center of the front-to-rear width of the table member 90. For example, if the centers of the lower roller 50 and the upper roller 60 are arranged near one end of the front-to-rear width of the loading surface 91 of the table member 90, when an object is placed near the other end of the loading surface 91 of the table member 90, the arm length L1 becomes approximately the length of the front-to-rear width of the loading surface 91, and the moment M acting on the table member 90 becomes approximately twice as large as when the centers of the lower roller 50 and the upper roller 60 are arranged so that they are approximately at the center of the front-to-rear width of the table member 90. Arranging the centers of the lower roller 50 and the upper roller 60 so that they are approximately at the center of the front-to-rear width of the table member 90 provides the best balance when an object is loaded on the loading surface 91, and such an arrangement is desirable in order to improve the stability of the lifting device 1.

[0043] Furthermore, when placing an object on the loading surface 91 during use of the lifting device 1, it is often the case that the object is placed near the center of the loading surface 91, or that the width of the loading surface 91 in the front-to-rear direction (X direction in the figure) is large (the center of gravity of the object is close to the center of the loading surface 91). In this case, when the centers of the lower roller 50 and the upper roller 60 are positioned so as to be approximately at the center of the front-to-rear width of the table member 90, the arm length L1 tends to become shorter, and as the arm length L1 becomes shorter, the moment M becomes smaller, so the force F acting on the rack support 20 and the guide support 30 becomes smaller, and the stability of the lifting device 1 can be improved.

[0044] Furthermore, with regard to the positional relationship between the lower rollers 50 and the upper rollers 60, which are arranged one above the other in the vertical direction, the longer the distance between the lower rollers 50 and the upper rollers 60, the greater the stability of the lifting device 1. When a load is placed as shown in Figure 9, i.e., when the values of W and L1 in equation (2) are fixed, the longer the distance between the lower rollers 50 and the upper rollers 60, i.e., the larger the value of L2, the smaller the force F acting on the rack support columns 20 and the guide support columns 30, thereby increasing the stability of the lifting device 1. The lower rollers 50 and the upper rollers 60 are arranged at a distance that is greater than or equal to a predetermined distance so that the lifting device 1 will not be damaged by moment M based on the intended use, i.e., the conditions of the load to be lifted or lowered by the lifting device 1, and so that the force F acting on the rack support columns 20 and the guide support columns 30 is equal to or less than a predetermined value.

[0045] As described above, the drive shaft 71 and roller shaft 72 are fixed to the shaft fixing plate 70, with the drive shaft 71 passing through the shaft center 50C of the lower roller 50 and the roller shaft 72 passing through the shaft center 60C of the upper roller 60. In other words, the vertical positional relationship between the lower roller 50 and the upper roller 60 is determined by the vertical positions at which the drive shaft 71 and the roller shaft 72 are fixed on the shaft fixing plate 70. By extending the shaft fixing plate 70 in the vertical direction, the distance between the lower roller 50 and the upper roller 60 can be increased, resulting in a lifting device 1 that does not lack stability even when lifting or lowering a heavy load.

[0046] In the lifting device 1, the upper limit of the lifting of the table member 90 is the height at which the upper rollers 60 contact the rack upper plate 22, and the lower limit is the height at which the lower rollers 50 contact the main frame 10 or the height at which the underside of the table frame 80 contacts the ground surface G. In other words, if the shaft fixing plate 70 is extended excessively relative to the height of the rack support 20 and the guide support 30, thereby increasing the distance between the lower rollers 50 and the upper rollers 60, the lifting range of the table member 90 will be limited by the distance between the lower rollers 50 and the upper rollers 60. For this reason, it is desirable that the vertical positional relationship between the lower rollers 50 and the upper rollers 60, i.e., the vertical positional relationship between the drive shaft 71 and the roller shaft 72, be arranged so that L2 is as long as possible within the range that ensures the required lifting range of the table member 90, based on the intended use of the lifting device 1.

[0047] When lifting or lowering a load using the lifting device 1, the load is placed on a table member 90 that is placed on and fixed to a horizontal pillar member 83, and the load is lifted or lowered. At this time, the table member 90 and the horizontal pillar member 83 may bend downward (opposite the Z direction in the figure) due to the weight of the load, causing the meshing between the racks 21 of the left and right rack supports 20 and the pinion gears 51 of the drive units 40 that are fixed to the left and right vertical pillar members 81A, 81B to tilt, resulting in uneven contact between the racks 21 and the pinion gears 51, which may reduce durability and strength. To address this problem, in the lifting device 1 of this embodiment, the horizontal pillar member 83 of the table frame 80 is configured to connect and integrate the left and right horizontal pillar members 83A and 83B at a central portion 83C, thereby suppressing deflection of the table member 90 and preventing poor meshing between the racks 21 and the pinion gears 51.

[0048] In this embodiment, an example has been described in which a load is unloaded from the ground G onto the bed of a truck T, but it is also possible to use it as a multi-story parking lot, for example, by expanding the loading surface 91 of the table member 90. By using a rack and pinion mechanism for the lifting method, the maximum lift height can be changed simply by extending the lengths of the rack support 20 and the guide support 30, and weight can be adjusted by extending the shaft fixing plate 70, widening the distance between the lower roller 50 and the upper roller 60, and changing the output capacity of the drive motor 41. In this way, specifications can be easily changed to suit different applications by changing some of the parts of the lifting device 1.

[0049] In this embodiment, the drive shaft 71 is disposed vertically below the roller shaft 72, but the drive shaft 71 may be disposed vertically above or below the roller shaft 72. When the drive shaft 71 is disposed vertically above the roller shaft 72, the upper roller 60 is provided on the drive shaft 71, and the lower roller 50 is provided on the roller shaft 72.

[0050] In this embodiment, the values of the outer diameters 50A and 60A of the lower roller 50 and the upper roller 60 are not particularly set, but the larger the outer diameters 50A and 60A, the fewer rotations required for lifting and lowering, which can reduce the power consumption of the drive motor 41. Therefore, it is desirable that the outer diameters 50A and 60A of the lower roller 50 and the upper roller 60 be as large as possible within the range in which they can be sandwiched and supported by the rack support 20 and the guide support 30. However, since the size of the outer diameters 50A and 60A affects the degree of meshing between the rack 21 and the pinion gear 51, the size must be determined taking into consideration the components of the rack 21 and the pinion gear 51.

[0051] The embodiments of the present invention have been described above in detail with reference to the drawings, but the specific configuration is not limited to the described embodiments, and the present invention also includes design changes and the like within the scope of the gist of the present invention. [Explanation of symbols]

[0052] 1: Lifting device, 10: Main frame, 11: Parallel side, 12: Divided side, 12A: Central part, 13: Mounting plate, 14: Wheel, 20: rack support, 21: rack, 22: rack upper plate, 30: guide support, 32: guide upper plate, 40: drive unit, 41: drive motor, 50: Lower roller, 51: Pinion gear, 60: Upper roller, 50A, 60A: outer diameter, 50B, 60B: shaft inner diameter, 50C, 60C: shaft center, 70: shaft fixing plate, 71: drive shaft, 72: roller shaft, 73: bearing, 80: table frame, 81, 81A, 81B: vertical column members, 82, 82A, 82B: frame members, 83, 83A, 83B: horizontal column members, 83C: central part, 90: table member, 91: loading surface, 92: boarding board, 93: boarding board, 94: stopper plate, 92A, 93A, 94A: rotating shaft, 95: bearing plate, 96: Switching arm, 97: Spring member, A, B: Width, G: Ground, T: Track

Claims

1. a drive motor connected to the drive shaft for rotating the drive shaft; a pinion gear fixed to the drive shaft; a roller shaft disposed vertically above or below the drive shaft; an upper roller and a lower roller mounted on the drive shaft and the roller shaft; a drive unit including the drive motor, a shaft fixing plate supporting the drive shaft and the roller shaft; a rack support and a guide support attached to a main frame while sandwiching the upper roller and the lower roller; a table frame fixed to the shaft fixing plate; a table member fixed to the table frame and having a loading surface on which an object is loaded, The rack support has: A rack that meshes with the pinion gear is formed along the longitudinal direction, The outer diameters of the upper roller and the lower roller are the upper roller and the lower roller are sized to allow the rack and the pinion gear to mesh appropriately when they are sandwiched between the rack support and the guide support, When the drive motor is driven, the pinion gear fixed to the drive shaft rotates while meshing with the rack, and the upper roller and the lower roller move up and down along the rack support and the guide support, thereby raising and lowering the table frame fixed to the shaft fixing plate and raising and lowering the table member fixed to the table frame.

2. The drive shaft and the roller shaft are The lifting device according to claim 1, wherein the lifting devices are arranged at least a predetermined distance apart in the vertical direction.

3. The table member is The vehicle has a boarding plate and an exit plate connected to the front and rear ends by a rotating shaft, The boarding board and the boarding outboard are The lifting device according to claim 1, which is capable of moving up and down around the rotation shaft.

4. The projection plate is When the table member is raised or lowered, it is folded at an angle of approximately 90 degrees.

4. The lifting device according to claim 3, further comprising a restricting means for restricting extension of the projection plate from a state in which the projection plate is folded at approximately 90 degrees.

5. The mainframe includes:

2. The lifting device according to claim 1, wherein the lifting device has a U-shape with three sides enclosed by four sides and one open, and the side opposite the opening can be separated at the center.

6. The drive motor is 2. The lifting device according to claim 1, wherein the shaft fixing plate is disposed so as to protrude outward from the table member.

7. The table member is a stopper plate is provided that rises upward from the loading surface and prevents the load from falling off the loading surface; The stopper plate is It can move around a rotation axis, At one end of the rotation shaft in the longitudinal direction, A switching arm that rotates the rotation shaft is attached to extend obliquely downward relative to the loading surface, The switching arm has: a spring member is provided to apply a torque to the rotation shaft to raise the stopper plate upward; The switching arm is When the table member descends, it is pushed by the ground surface and rotates upward, rotating the rotation shaft and causing the stopper plate to fall down.

2. The lifting device according to claim 1, wherein when the table member is raised, the table member rotates downward by the elastic force of the spring member, causing the rotation shaft to rotate and the stopper plate to rise.

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