Lift mechanism for unmanned transport vehicle and unmanned transport vehicle equipped with the lift mechanism

Abstract

To achieve a lower center of gravity by simplifying the structure of an unmanned transport vehicle, and reduce the load on the drive source when the platform is raised to its highest position, thereby making the drive source more compact.SOLUTION: A lift mechanism 4 is configured to raise and lower a platform 3 on which an object to be transported is placed, relative to a vehicle chassis 2 of an unmanned transport vehicle 1. The lift mechanism 4 includes a drive motor 40, a rotatable rotary shaft 43 drivingly connected to the drive motor 40, a first link member 45 having one end fixed to the rotary shaft 43 and rotatable together with the rotary shaft 43, and a second link member 46 having one end rotatably connected to the other end of the first link member 45 via a connecting shaft 47 and the other end rotatably connected to the platform 3. As the first link member 45 rotates, the second link member 46 rotates around the connecting shaft 47, and the other end of the second link member 46 moves up and down, thereby raising and lowering the platform 3.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to an automated guided vehicle equipped with a lift mechanism for raising and lowering a platform on which an object is to be carried, relative to a vehicle chassis, and more particularly to an improvement in the structure of the lift mechanism. [Background technology]

[0002] Known examples of automated guided vehicles that transport objects autonomously include AGVs (Automatic Guided Vehicles), AMRs (Autonomous Mobile Robots), and AIVs (Autonomous Intelligent Vehicles). AGVs are generally unmanned vehicles that travel guided by magnetism emitted by magnetic tapes or the like laid on the floor, while AMRs and AIVs are generally vehicles that can travel autonomously based on route information created by the robot itself.

[0003] Among such automated guided vehicles, those equipped with a lift mechanism (elevation mechanism) for raising and lowering a platform on which an article is placed relative to the vehicle chassis are in practical use.

[0004] For example, JP 2023-107186 A describes a mechanism in which a connecting shaft member (83) and a right and left screw (77) are rotated by driving a rotary motor (90) via pulleys (87, 88) and a belt (89) of a power transmission mechanism (86), and thereby a pair of nuts (76, 76) that are screwed into the right and left screw (77) move toward or away from each other, thereby operating a pantograph-like arm mechanism, thereby raising and lowering a connection mechanism (100) relative to a base (11) (see paragraphs

[0096] to

[0097] ,

[0117] ,

[0120] to

[0121] ,

[0126] to

[0127] , and Figures 11 to 16). In addition, in the device described in the same publication, when the left-right screw (77) and the connecting shaft member (83) are raised and lowered by the operation of the pantograph-shaped arm mechanism, the support arm (81) rotates around the axis of the connecting shaft member (83) (paragraphs

[0123] ,

[0129] , Figures 17 to 19). Summary of the Invention [Problem to be solved by the invention]

[0005] In the lift mechanism described in the above publication, in addition to the rotary motor (90), power transmission mechanism (86), and arm mechanism, the lift mechanism further requires a right and left screw (77), a connecting shaft member (83), nuts (76, 76), and a support arm (81), resulting in a complex structure. In addition, when the lift mechanism is used to raise the vehicle, the right and left screw (77), nuts (76, 76), and pulley (88) move upward (see Figures 17 to 19), which causes the center of gravity of the entire automatic guided vehicle to move upward, which is a drawback.

[0006] The present invention has been made in consideration of the conventional situation, and the problem which the present invention aims to solve is to provide a lift mechanism for an unmanned guided vehicle which can simplify the structure, achieve a lower center of gravity for the unmanned guided vehicle, and reduce the load on the drive source when the loading platform is at the highest position, thereby enabling the drive source to be made smaller. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a lift mechanism for raising and lowering a platform on which an object to be transported is placed relative to a vehicle chassis in an unmanned guided vehicle, the lift mechanism comprising: a drive source; a rotatable shaft drivingly connected to the drive source; a first link member having one end fixed to the rotating shaft and rotatable together with the rotating shaft; and a second link member having one end rotatably connected to the other end of the first link member via a connecting shaft and having the other end rotatably connected to the platform; and as the first link member rotates, the second link member rotates around the connecting shaft and the other end of the second link member moves in the vertical direction, thereby raising and lowering the platform.

[0008] In the present invention, when the mounting table is raised or lowered, the rotary shaft is rotated by the driving source, and the first link member having one end fixed to the rotary shaft rotates together with the rotary shaft, and then the second link member having one end connected to the other end of the first link member via a connecting shaft rotates about the connecting shaft, whereby the other end of the second link member moves up and down, raising and lowering the mounting table.

[0009] According to the present invention, the lift mechanism for raising and lowering the mounting table is composed of a drive source, a rotating shaft, and first and second link members, and therefore the structure can be simplified. In this case, when the mounting table is raised, the first link member rotates due to the rotation of the rotating shaft, and the second link member rotates around the connecting shaft, and the other end of the second link member moves to an upper position. Therefore, when the mounting table is raised, the center of gravity of the automated guided vehicle does not shift significantly to an upper position, and the center of gravity of the automated guided vehicle can be lowered, and a large upward pushing force can be generated on the mounting table when the mounting table is raised to the highest position, thereby reducing the load on the drive source and making the drive source smaller.

[0010] In the present invention, the rotating shaft and the connecting shaft are vertically aligned at the uppermost position of the mounting table (i.e., the most elevated position (top dead center)). In this case, a very large pushing-up force can be applied to the mounting table from the other end of the second link member, so that the load on the drive source can be further reduced and the drive source can be made even smaller.

[0011] In the present invention, the first and second link members are provided on both the left and right sides of the chassis, respectively.

[0012] In the present invention, the first and second link members are provided at the front or rear of the chassis, and at the front or rear of the chassis, there are provided a rotatable third link member that is drivingly connected to the first link member via a connecting rod, and a fourth link member having one end rotatably connected to the other end of the third link member and the other end rotatably connected to the mounting base.

[0013] In this case, when the mounting table is raised or lowered, when the rotating shaft is rotated by the driving source, the first link member having one end fixed to the rotating shaft rotates together with the rotating shaft, and the third link member rotates via the connecting rod. Then, the second link member having one end connected to the other end of the first link member via a connecting shaft rotates about the connecting shaft, and the fourth link member having one end rotatably connected to the other end of the third link member rotates. As a result, the other ends of the second and fourth link members move up and down, thereby raising and lowering the mounting table.

[0014] In the present invention, the third and fourth link members are provided on both the left and right sides of the chassis, respectively.

[0015] In the present invention, a guide portion for guiding the lifting and lowering of the platform is provided between the chassis and the platform.

[0016] The automated guided vehicle according to the present invention includes the lift mechanism.

[0017] In the present invention, the unmanned guided vehicle has front and rear wheels arranged at the front and rear of the chassis, and drive wheels for running arranged in the fore-and-aft center of the chassis, and the drive source, rotating shaft, and first and second link members are arranged between the drive wheels and the front wheels or rear wheels.

[0018] In this case, the drive wheels for running are positioned in the fore-and-aft center of the chassis, thereby improving the weight balance, and thus improving not only the static balance but also the dynamic balance during turning, thereby enabling turning operations to be performed smoothly.

[0019] In the present invention, the drive source, the rotating shaft, the first link member and the connecting shaft are disposed below the upper surface of the chassis, thereby ensuring a low center of gravity and a low floor for the automated guided vehicle. Effect of the Invention

[0020] As described above, according to the present invention, it is possible to simplify the structure, to achieve a lower center of gravity for the automatic guided vehicle, and to reduce the load on the drive source when the mounting platform is raised to the maximum position, thereby enabling the drive source to be made smaller. [Brief description of the drawings]

[0021] [Figure 1] 1 is an overall perspective view of an automated guided vehicle (AMR) employing a lift mechanism according to an embodiment of the present invention, as viewed from above on the front side; [Diagram 2] FIG. 2 is an overall perspective view of the automatic guided vehicle (FIG. 1) as viewed from above on the rear side. [Diagram 3] FIG. 2 is an overall perspective view of the automatic guided vehicle (FIG. 1) as viewed from above on the side. [Figure 4] FIG. 2 is a side view of the automated guided vehicle (FIG. 1). [Diagram 5] FIG. 2 is an overall perspective view of the automatic guided vehicle (FIG. 1) as viewed from below on the side. [Figure 6] FIG. 2 is a bottom view of the automated guided vehicle (FIG. 1). [Figure 7] FIG. 2 is a perspective view showing an overall configuration of a lift mechanism of the automatic guided vehicle (FIG. 1). [Figure 8] FIG. 8 is a partially enlarged view of the lift mechanism (FIG. 7). [Figure 9] FIG. 8 is a side view of the lift mechanism (FIG. 7). [Figure 10] FIG. 8 is a side view, partially cut away, of the lift mechanism (FIG. 7). [Figure 11] FIG. 11 is a side view of the lift mechanism (FIG. 7) corresponding to FIG. 10, showing the state in which the mounting table has reached the top dead center after being raised to the uppermost position. [Figure 12] FIG. 11 is a side view of the lift mechanism (FIG. 7) corresponding to FIG. 10, showing a state in which the mounting table is in the middle of rising. [Figure 13] FIG. 11 is a side view of the lift mechanism (FIG. 7) corresponding to FIG. 10, showing the state in which the mounting table has reached the bottom dead center after being lowered to the lowest position. [Figure 14] FIG. 14 is a schematic diagram of the lift mechanism (FIG. 7) and corresponds to FIG. 13. [Figure 15]FIG. 13 is a schematic diagram of the lift mechanism (FIG. 7) and corresponds to FIG. 12. [Figure 16] FIG. 12 is a schematic diagram of the lift mechanism (FIG. 7) and corresponds to FIG. 11. [Figure 17] 8 is a diagram for explaining a force acting on the mounting table from an upper link in the lift mechanism (FIG. 7). FIG. [Figure 18] 13 is a diagram for explaining a force acting on a mounting table from a single rotating cam as a comparative example. FIG. [Figure 19] 1 is a graph showing the relationship between the lift force and stroke (lift amount) on the mounting table in a lift mechanism according to the present invention (product of the present invention), in comparison with a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Figures 1 to 17 and 19 are diagrams for explaining a lift mechanism according to an embodiment of the present invention, where Figures 1 to 6 are diagrams showing an automated guided vehicle equipped with the lift mechanism, Figures 7 to 13 are diagrams for explaining the lift mechanism, Figures 14 to 16 are diagrams showing the lift mechanism and its operation, Figure 17 is a diagram for explaining the force acting on the platform from the upper link of the lift mechanism, and Figure 19 is a graph showing the relationship between the lift force on the platform and the stroke (lift amount). Figure 18 is a diagram for explaining the force acting on the platform from a single rotating cam as a comparative example of the present invention, and corresponds to Figure 17. For ease of explanation, in Fig. 4 (side view), the right side (same in Fig. 5 and Fig. 6) is referred to as the front (front side), the left side (same in Fig. 5 and Fig. 6) is referred to as the rear (rear side), the left and right directions are referred to as the front-rear direction, the top is referred to as the top (upper side), the bottom is referred to as the bottom (lower side), and the direction perpendicular to the plane of the drawing is referred to as the left-right direction (width direction). Note that an automated guided vehicle can travel (run) in either the forward or backward direction.

[0023] Here, an autonomous mobile robot (AMR) will be described as an example of an autonomous guided vehicle, but the present invention can be similarly applied to an automatic guided vehicle (AGV), an autonomous intelligent vehicle (AIV), and other autonomous guided vehicles.

[0024] As shown in Figures 1 to 6, the automated guided vehicle 1 includes a chassis 2 and a platform 3 that is movable in the vertical direction (i.e., can be raised and lowered) relative to the chassis 2 and on which an object to be transported (not shown) is placed.

[0025] In addition to the lift mechanism 4 according to this embodiment (described in detail later), the chassis 2 has a pair of left and right front wheels 10 and rear wheels 11 (see Figs. 4 to 6) rotatably supported on the front and rear sides of the chassis 2, a pair of left and right drive wheels 12 for traveling rotatably provided in the center of the chassis 2 in the front-rear direction, and a travel motor 13 (see Figs. 4 to 6) for driving each of the drive wheels 12. The drive wheels 12 and the travel motor 13 have an integrated structure. The lift mechanism 4 is disposed between the rear wheels 11 and the drive wheels 12. A control box 18 for controlling the drive of the lift mechanism 4 and the like is provided between the front wheels 10 and the drive wheels 12. A battery 15 for the travel motor 13 is provided on the side of the lift mechanism 4 between the rear wheels 11 and the drive wheels 12. In addition, a safety laser scanner 16 for detecting people and obstacles and an emergency stop button 17 for emergency stopping the automatic guided vehicle 1 while traveling are provided at the front and rear ends of the chassis 2.

[0026] Next, the configuration of the lift mechanism 4 will be described in detail with reference to FIGS. As shown in Figs. 7 and 8, the lift mechanism 4 has a drive motor 40 as a drive source. Here, a brushless motor is used as the drive motor 40, but various other motors may be used. The drive motor 40 is a geared motor including a reduction gear unit 41. A gear 42 is attached to the output shaft of the drive motor 40. Meanwhile, a rotating shaft 43 extending in the left-right direction (the chassis width direction) is disposed on the chassis 2. In this example, the rotating shaft 43 is extended from one side to the other side of the chassis 2 at the rear side of the chassis 2, and is supported by the chassis 2 so as to be freely rotatable. A gear 44 meshing with the gear 42 is fixed to the rotating shaft 43.

[0027] With this configuration, the rotational force of the drive motor 40 is transmitted to the rotating shaft 43 via the gears 42 and 44 (i.e., the rotating shaft 43 is drivingly connected to the drive motor 40). The gear 42 may be mounted so as to slip around the mounting shaft when excessive torque acts from the gear 44 side. This is to prevent damage to the reduction gear unit 41 including the gear 42 when excessive rotational force (overload) acts from the rotating shaft 43 side due to overloading of the mounting table 3, etc.

[0028] As shown in Figures 9 and 10, a first link member (or a first cam member) 45 is fixed to the left and right ends of the rotation shaft 43 of the lift mechanism 4. Although Figures 9 and 10 show the link mechanism 4 on the right side (the right side when facing the front) of the chassis 2, the left link mechanism 4 is similar, and only the right link mechanism 4 will be described here.

[0029] In this example, the first link member 45 is a link member (or cam member) having a polygonal shape when viewed from the front, and one end (the central part in this example) of the first link member 45 is fixed to the shaft end of the rotating shaft 43 by a key or the like. This allows the first link member 45 to rotate together with the rotating shaft 43. One end of a second link member 46 having a rectangular shape extending in the longitudinal direction is rotatably connected to the other end (the upper end in the examples of Figs. 9 and 10) of the first link member 45 via a connecting shaft 47. The other end of the second link member 46 is rotatably connected to, for example, the lower surface (or side surface) of the mounting table 3. A bracket member 48 having, for example, a U-shape is attached to the lower surface (or side surface) of the mounting table 3, and the other end of the second link member 46 is rotatably connected to the bracket member 48 by a pin 49 that passes through the bracket member 48 and the other end. With this configuration, when the first link member 45 rotates, the second link member 46 rotates around the connecting shaft 47, while the other end of the second link member 46 moves up and down.

[0030] A short rotating shaft 43' is rotatably supported on both the left and right sides of the front side of the chassis 2 (see Figs. 7 and 8). A third link member (or a third cam member) 45' having a shape similar to that of the first link member 45 on the rear side is provided on each rotating shaft 43', and the shaft end of the rotating shaft 43' is fixed to one end (the center part in this example) of the third link member 45' by a key or the like. One end of a rectangular fourth link member 46' extending in the longitudinal direction is rotatably connected to the other end (the upper end in the examples of Figs. 9 and 10) of the third link member 45' via a connecting shaft 47'. The other end of the fourth link member 46' is rotatably connected to, for example, the lower surface (or side surface) of the mounting table 3, similar to the second link member 46 on the rear side. A U-shaped bracket member 48', for example, is attached to the underside (or side) of the stand 3, and the other end of the fourth link member 46' is rotatably connected to the bracket member 48' by a pin 49' that passes through the bracket member 48' and the other end.

[0031] The front third link member 45' is connected to the rear first link member 45 via a connecting rod 50 extending in the front-rear direction (see Figs. 7 and 8). The front end of the connecting rod 50 is connected to the third link member 45' so as to be rotatable about a connecting shaft 51' connecting the front ends, and the rear end of the connecting rod 50 is connected to the first link member 45 so as to be rotatable about a connecting shaft 51 connecting the rear ends. With this configuration, the rotation of the first link member 45 causes the connecting rod 50 to rotate around the rotation shaft 43 and swing in the front-rear direction, thereby rotating the third link member 45'.

[0032] Also, guide parts 55, 55' for guiding the lifting and lowering of the mounting platform 3 are provided on both the left and right sides of the front and rear ends of the chassis 2, respectively (see Figs. 7 to 10). The guide part 55 is arranged on both the left and right sides of the rear end of the chassis 2, and the guide part 55' is arranged on both the left and right sides of the front end of the chassis 2. The guide part 55 is arranged between the chassis 2 and the mounting platform 3, and has a guide body 55a fixed to the chassis 2 side, and a piston 55b provided so as to be able to protrude and retract from the guide body 55a (i.e., be extendable and retractable), and the tip of which is connected to the lower surface (or side) of the mounting platform 3. Similarly, the guide part 55' is arranged between the chassis 2 and the mounting platform 3, and has a guide body 55'a fixed to the chassis 2 side, and a piston 55'b provided so as to be able to protrude and retract from the guide body 55'a (i.e., be extendable and retractable), and the tip of which is connected to the lower surface (or side) of the mounting platform 3.

[0033] 9 and 10, the rotating shaft 43, the first link member 45, and the connecting shaft 47 are disposed below the upper surface 2A of the chassis 2, thereby realizing a low center of gravity of the automated guided vehicle 1. Similarly, the rotating shaft 43', the third link member 45', and the connecting shaft 47' are also disposed below the upper surface 2A of the chassis 2, thereby realizing a low center of gravity of the automated guided vehicle 1.

[0034] 9 and 10 show a state in which the mounting table 3 has reached the uppermost position (i.e., the most elevated position (top dead center)), and at this time, as shown in each figure, the rotating shaft 43 and the connecting shaft 47 are aligned in the vertical direction (i.e., arranged in a straight line in the vertical direction). Similarly, at this time, the rotating shaft 43' and the connecting shaft 47 are also aligned in the vertical direction (i.e., arranged in a straight line in the vertical direction). More preferably, at this time, the second link member 46 and the fourth link member 46' are arranged in a direction perpendicular to the mounting table 3 extending in the horizontal direction.

[0035] Next, the effects of this embodiment will be described with reference to FIGS. Here, Fig. 11 to Fig. 13 are side views (right side views in the traveling direction of the chassis 2) of the lift mechanism 4 (Fig. 7), Fig. 11 shows the state where the platform has reached the highest position (top dead center), Fig. 12 shows the state where the platform is in the middle of rising, and Fig. 13 shows the state where the platform has reached the lowest position (i.e., the lowest position (i.e., bottom dead center)). Also, Fig. 14 to Fig. 16 are schematic diagrams of Fig. 13, Fig. 12, and Fig. 11, respectively, and in each figure, for convenience of illustration, the connecting rod 50 is omitted.

[0036] First, as shown in Fig. 13 and Fig. 14, when the mounting table 3 is at the lowermost position (bottom dead center), the rotation of the rotary shaft 43 by the drive motor 40 causes the connecting shaft 47 to be located below the rotary shaft 43, and the linear region (Fig. 13) from the rotary shaft 43 to the connecting shaft 47 in the first link member 45 (Fig. 14) or the first link member 45 intersects at an acute angle with the second link member 46. Also, at this time, the rotation of the rotary shaft 43 causes the connecting rod 50 (Fig. 13) to move rearward (leftward in Fig. 13), causing the connecting shaft 47' to be located below the rotary shaft 43', and the linear region (Fig. 13) from the rotary shaft 43' to the connecting shaft 47' in the third link member 45' (Fig. 14) or the third link member 45' intersects at an acute angle with the fourth link member 46'. The second link member 46 and the fourth link member 46' abut against the mounting base 3 via pins 49, 49' (see Figure 14) or via bracket members 48, 48' to which the pins 49, 49' are respectively connected (see Figure 12) (the same applies to Figures 11, 12, 15 and 16).

[0037] 13 and 14, the first link member 45 rotates together with the rotating shaft 43 due to the rotation of the rotating shaft 43 by the drive motor 40, and the state transitions to the state shown in Fig. 12 and 15. At this time, the connecting shaft 47 is disposed above the rotating shaft 43, and the connecting rod 50 (Fig. 12) moves forward (to the right in Fig. 12) due to the rotation of the rotating shaft 43, so that the connecting shaft 47' is also disposed above the rotating shaft 43'. As a result, the second link member 46 and the fourth link member 46' move upward while rotating around the connecting shafts 47, 47', and as a result, the mounting table 3 moves upward.

[0038] 12 and 15, the first link member 45 further rotates together with the rotating shaft 43 due to the rotation of the rotating shaft 43 by the drive motor 40, and transitions to the state shown in Figures 11 and 16. At this time, the connecting shaft 47 moves further upward relative to the rotating shaft 43 and is located directly above the rotating shaft 43. At this time, the connecting rod 50 (Figure 11) moves forward (to the right in Figure 11) due to the rotation of the rotating shaft 43, and the connecting shaft 47' moves further upward relative to the rotating shaft 43' and is located directly above the rotating shaft 43'.

[0039] As a result, the second link member 46 and the fourth link member 46' move further upward while rotating around the connecting shafts 47, 47', so that the first link member 45 and the second link member 46 are vertically arranged in a straight line, and the third link member 45' and the fourth link member 46' are vertically arranged in a straight line. At this time, the pin 49, the connecting shaft 47 and the rotating shaft 43 are vertically arranged in a straight line, and similarly, the pin 49', the connecting shaft 47' and the rotating shaft 43' are vertically arranged in a straight line. As a result, the mounting table 3 moves further upward and reaches the highest position (top dead center).

[0040] Here, Figure 17 shows a state in which the lift mechanism is in the middle of transitioning from Figure 15 to Figure 16. The forces acting on each part at this time will be considered. 17, a perpendicular line P is drawn through the center O of the rotating shaft 43 and perpendicular to the mounting table 3 (the perpendicular line P passes through the center B of the pin 49). The center of the connecting shaft 47 is designated as A, and the angle (∠AOB) that the first link member 45 makes with the perpendicular line P is designated as α. The first link member 45 rotates counterclockwise around the center O of the rotating shaft 43 (in the figure, an arc 47A indicated by a dashed line indicates the rotation circle of the center A of the connecting shaft 47). If the force in the tangential direction of the rotation circle 47A acting on the connecting shaft 47 (tangential force, i.e., rotational force) is designated as F and the force in the normal direction of the rotation circle 47A (normal force) is designated as F1, then a resultant force F2 of the tangential force F and the normal force F1 acts along the arrangement direction of the second link member 46. For the sake of simplicity, an example will be taken in which the first link member 45 and the second link member 46 have the same length.

[0041] Since △OAB is an isosceles triangle, ∠ABO=α, and ∠BAO=180°-2α Therefore, the angle that the resultant force F2 makes with the tangential force F is 90°-2α. If we express the resultant force F2 using the tangential force F, we get F2×cos(90°-2α)=F Therefore, F2×sin2α=F Therefore, F2 = F / sin2α … (1) It becomes.

[0042] On the other hand, the resultant force F2 acts in an oblique direction on the mounting table 3. When the force F2 is decomposed into a direction perpendicular to the mounting table 3 and a direction parallel to the mounting table 3, the perpendicular component F P corresponds to the pushing force that pushes the table 3 upward. P The angle it makes with force F2 is α. Push-up force F P Expressing this using force F2, we get F P =F2 × cosα …(2) Substituting equation (1) into equation (2), we get F P =(F / sin2α)×cosα …(3) Here, sin2α=2sinαcosα, so Equation (3) is F P =(F / 2sinαcosα)×cosα=F / 2sinα …(4) This can be expressed as:

[0043] As the first link member 45 further rotates counterclockwise around the center O of the rotating shaft 43 from the state shown in Figure 17, the angle α gradually becomes smaller, and when the connecting shaft 47 moves to a position directly above the rotating shaft 43 (see Figures 10 and 16), the angle α becomes 0. In formula (4), When α→0, sinα→0, so 1 / sinα→∞, so F P →It becomes ∞.

[0044] Therefore, the pushing force F P The smaller the angle α, the larger the lifting force F P becomes ∞. As a result, when the mounting table 3 is raised to the top, the load on the driving motor 40 can be reduced (as a result, the current consumption can be reduced), and the driving motor 40 can be made smaller.

[0045] Fig. 18 is a comparative example of Fig. 17, and in Fig. 18, the same reference numerals as in Fig. 17 indicate the same or corresponding parts. In Fig. 18, a rotational force acts around a pin 100 arranged at one end of a rotating cam 101, so that the rotating cam 101 can rotate around a center O of the pin 100, and a pin 102 arranged at the other end of the rotating cam 101 abuts against the mounting table 3. That is, the mechanism in Fig. 18 is composed of a single rotating cam 101, unlike the mechanism in Fig. 17.

[0046] 18, a perpendicular line P is drawn through the center O of the pin 100 and perpendicular to the table 3, and the angle between the rotating cam 101 and the perpendicular line P is θ. The rotating cam 101 rotates counterclockwise around the center O (in the figure, the arc 102A shown by the dashed line indicates the rotation circle of the center A of the pin 102). At this time, the force (push-up force) acting from the pin 102 in the direction perpendicular to the table 3 is F.P Then, the force F acting on the pin 102 in the tangential direction of the rotation circle 102A (tangential force, i.e., rotational force) is F P × sinθ. On the other hand, if the distance between the center A of the pin 102 and the center O of the pin 100 when the pin 102 is disposed on the perpendicular line P is L1, and the distance between the center A of the pin 102 and the center O of the pin 100 when the rotating cam 101 is disposed at an angle θ with respect to the perpendicular line P is L2, then For the moment of force around the center O, F×L1=F P ×sinθ×L2…(5) holds true. Here, for the sake of simplicity, the case where L1=L2 is taken as an example. In this case, from equation (5), F=F P ×sinθ Therefore, F P =F / sinθ …(6) It becomes

[0047] In the formula (6), When θ→0, sinθ→0, so 1 / sinθ→∞, so F P →It becomes ∞. For this reason, even in the comparative example, the pushing-up force F P In theory, when the angle θ is 0, it becomes infinity.

[0048] Next, FIG. 19 shows the lift force (push-up force) F applied to the table 3 in the present lift mechanism (the present invention) and the comparative example. P 1 is a graph showing the relationship between the input torque (motor torque) and the stroke (lift amount). The figure shows an example of an input torque (motor torque) of 54 [Nm] and a total stroke of 40 [mm]. In the figure, the bottom dead center of the mounting table 3 is when the stroke is 0 [mm], and the top dead center is when the stroke is 40 [mm].

[0049] As can be seen from the figure, in the case of the present invention, at the top dead center (stroke 40 [mm]), theoretically, the pushing force F Pis ∞, and in the comparative example as well, at the top dead center (stroke 40 [mm]), theoretically, the pushing force F P In addition, in the case of the present invention, the pushing force F is larger than that of the comparative example in the entire range up to the top dead center. P That is, when the stroke is less than 40 mm, the rotation angle (movement amount) of the link mechanism is larger than that of the comparative example under the same stroke, and therefore the present invention can obtain a larger lifting force.

[0050] For example, by preventing the platform from coming into contact with the transported object (luggage) when the stroke is in the range of 0 to 30 mm, and by having the platform come into contact with the transported object and lift and transport it when the stroke is in the range of 30 to 40 mm, it becomes possible to lift and transport the object only when the lifting force is increasing and only when the lifting force is very large, thereby further reducing the load on the drive motor (resulting in a further reduction in current consumption) and making the drive motor even smaller.

[0051] As described above, in the present invention, the pushing-up force F P Not only can a maximum force of ∞ be obtained as a force, but also a high lifting force can be obtained at the stroke position where the transported object is pushed up.

[0052] As described above, according to this embodiment, the lift mechanism 4 for raising and lowering the mounting table 3 is composed of the drive motor 40, the rotary shaft 43, and the first and second link members 45 and 46, and therefore the structure can be simplified. Moreover, when the mounting table 3 is raised, the first link member 45 rotates due to the rotation of the rotary shaft 43, and the second link member 46 rotates about the connecting shaft 47, and the other end of the second link member 46 moves to an upper position. Therefore, when the mounting table 3 is raised, the center of gravity of the automatic guided vehicle 1 is not significantly displaced to an upper position, and the center of gravity of the automatic guided vehicle 1 can be lowered, and a large lifting force can be generated on the mounting table 3 when the mounting table 3 is raised to the highest position, thereby reducing the load on the drive motor 40 and making the drive motor 40 smaller.

[0053] Furthermore, since the first and third link members 45, 45' are disposed at four positions on the front, rear, left and right of the chassis 2, the unmanned guided vehicle 1 can withstand unbalanced loads acting from the front, rear, left and right directions. This makes it possible to prevent the unmanned guided vehicle 1 from tilting due to various unbalanced loads, so accurate positioning of the platform 3 with respect to the transported object is not necessary, and the object can be transported without collapse even with rough positioning.

[0054] Also, since there is no need to place the drive motor 40 of the lift mechanism 4 in the center of the chassis, but can be placed at the end of the chassis 1, the space at the end of the chassis can be used effectively. Meanwhile, since the travel motor 13 for driving each drive wheel 12 can be placed at the center of the chassis, not only the weight balance (static balance) of the automated guided vehicle 1 can be improved, but also the turning balance (dynamic balance), enabling smooth turning operations. Furthermore, since the drive motor 40 is placed under the chassis 2, the automated guided vehicle 1 can have a lower center of gravity and a lower floor.

[0055] Although the preferred embodiment of the present invention has been described above, the application of the present invention is not limited to this, and the present invention includes various modified examples. Some examples of the modified examples are given below.

[0056] [First Modification] In the above embodiment, the rotating shaft 43 of the lift mechanism 4 and the first and second link members 45, 46 are disposed on the rear side of the chassis 2 (more specifically, between the drive wheels 12 and the rear wheels 11 (see FIG. 5)), and the third and fourth link members 45', 46' are disposed on the front side of the chassis 2 (more specifically, between the drive wheels 12 and the front wheels 10 (see FIG. 5)), but the application of the present invention is not limited to this. The first and second link members 45, 46 may be disposed on the front side of the chassis 2, and the third and fourth link members 45', 46' may be disposed on the rear side of the chassis 2.

[0057] [Second Modification] In the above embodiment, the first link member 45 and the third link member 45' are each formed in a polygonal shape, but the first link member 45 and the third link member 45' may have any other appropriate shape.

[0058] [Third Modification] 9 to 13 of the embodiment, the second and fourth link members 46, 46' are longer in the longitudinal direction than the first and third link members 45, 45', respectively, but the application of the present invention is not limited to this. As shown in Figs. 14 to 16, the second and fourth link members 46, 46' may have the same length as the first and third link members 45, 45', respectively. Alternatively, the first and third link members 45, 45' may be longer in the longitudinal direction than the second and fourth link members 46, 46', respectively (not shown).

[0059] [Fourth Modification] In the above embodiment, the rotational force of the first link member 45 is transmitted to the third link member 45' via the connecting rod 50, but the application of the present invention is not limited to this. For example, gears and timing pulleys may be attached to the rotating shafts 43 and 43', respectively, and chains and timing belts may be wound around these gears and timing pulleys, respectively.

[0060] [Fifth Modification] In the above embodiment, an example is shown in which the guide portion 55 for guiding the lifting and lowering of the mounting table 3 is provided, but the guide portion 55 may be omitted.

[0061] [Other Modifications] The above-described embodiments and modifications should be considered in all respects as merely illustrative of the present invention, and are not limiting. Those skilled in the art to which the present invention pertains may, without departing from the spirit and essential characteristics of the present invention, construct various modifications and other embodiments that incorporate the principles of the present invention when considering the teachings above, even if not expressly described herein. [Industrial Applicability]

[0062] As described above, the present invention is useful for a lift mechanism of an automated guided vehicle, and is suitable for a lift mechanism that simplifies the structure, realizes a lower center of gravity for the automated guided vehicle, and reduces the load on the drive source when the loading platform is at the highest position, thereby making the drive source smaller. [Explanation of symbols]

[0063] 1: Automated guided vehicle 2: Chassis 2A: Top surface 3: Placement table 4: Lift mechanism 40: Drive motor (drive source) 43: Rotation axis 45: First link member 46: Second link member 47: Connection shaft 45': Third link member 46': Fourth link member 47': Connection shaft 50: Connecting rod 10: Front wheel 11: Rear wheel 12: Drive wheels [Prior art documents] [Patent documents]

[0064] [Patent Document 1] JP 2023-107186 A (see paragraph

[0037] and FIG. 4)

Claims

1. A lift mechanism for raising and lowering a platform on which an object is to be carried with respect to a vehicle chassis in an automated guided vehicle, The lift mechanism is A driving source; A rotatable rotation shaft drivingly connected to the drive source; a first link member having one end fixed to the rotation shaft and rotatable together with the rotation shaft; a second link member having one end rotatably connected to the other end of the first link member via a connecting shaft and having the other end rotatably connected to the mounting table; Equipped with As the first link member rotates, the second link member rotates about the connecting shaft, and the other end of the second link member moves in a vertical direction, thereby lifting and lowering the mounting table. A lift mechanism for an automated guided vehicle.

2. In claim 1, When the mounting table is at the highest raised position, the rotating shaft and the connecting shaft are aligned in the vertical direction. A lift mechanism for an automated guided vehicle.

3. In claim 1, The first and second link members are provided on both left and right sides of the chassis, respectively. A lift mechanism for an automated guided vehicle.

4. In claim 1, the first and second link members are provided on the front or rear side of the chassis, A rotatable third link member is provided on the rear or front side of the chassis, the third link member being drivably connected to the first link member via a connecting rod, and a fourth link member is provided on one end of the fourth link member rotatably connected to the other end of the third link member and on the other end of the fourth link member rotatably connected to the stand. A lift mechanism for an automated guided vehicle.

5. In claim 4, The third and fourth link members are provided on both left and right sides of the chassis, respectively. A lift mechanism for an automated guided vehicle.

6. In claim 1, A guide portion for guiding the raising and lowering of the stand is provided between the vehicle chassis and the stand. A lift mechanism for an automated guided vehicle.

7. An automated guided vehicle comprising the lift mechanism according to claim 1.

8. In claim 7, the automated guided vehicle has front and rear wheels disposed at the front and rear of the chassis, and a drive wheel for running disposed at a center portion of the chassis in the front-rear direction, The driving source, the rotating shaft, and the first and second link members are disposed between the driving wheels and the front wheels or the rear wheels. An unmanned transport vehicle characterized by the above.

9. In claim 8, the driving source, the rotating shaft, the first link member and the connecting shaft are disposed below an upper surface of the chassis; An unmanned transport vehicle characterized by the above.

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