Lifting device, transport cart

Abstract

To provide a lifting / lowering device designed to reduce the height of a stage in a lifting / lowering direction while reducing buckling of a push chain.SOLUTION: A lifting / lowering device includes a push chain (10), a stage (12), a guide (14), and a sprocket (16). The push chain has a first straight rod portion (10A) along a first direction (D1), a second straight rod portion (10B) along a second direction (D2), and a first bent portion (10C) between the first straight rod portion and the second straight rod portion. A stage is formed on the first straight rod portion and is lifted / lowered along the first direction. The sprocket is engaged with the push chain on a side of the second straight rod portion with respect to the first bent portion.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lifting device including a push chain, and a transport vehicle equipped with the lifting device. [Background technology]

[0002] Patent Document 1 discloses a transport cart that is used in an automobile production line for assembling parts onto a vehicle body and has the function of transporting and lifting a vehicle body. In Patent Document 1, an interlocking chain is used to lift and lower a support part that supports the vehicle body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-30304 A Summary of the Invention [Problem to be solved by the invention]

[0004] From the viewpoint of reducing costs and simplifying the device, it is possible to replace the interlocking chains of Patent Document 1 with a single push chain. However, in this case, in order to reduce buckling of the push chain, it is necessary to provide a push chain guide with a certain height in the lifting direction of the support part, which leads to an increase in the size of the lifting mechanism in the lifting direction of the support part.

[0005] Therefore, in a transport cart equipped with the above-mentioned lifting mechanism, the height of the floor on which a worker stands who works on the vehicle body raised and lowered by the lifting mechanism increases. In order to reduce the height of the floor while maintaining the height of the lifting mechanism in the lifting direction, it is necessary to complicate the structure of the lifting mechanism or the floor, and there is a possibility that the distance that the lifting mechanism can raise and lower will be shortened. [Means for solving the problem]

[0006] A lifting device according to one embodiment of the present invention has a first straight rod portion along a first direction, a second straight rod portion along a second direction different from the first direction, and a first bent portion between the first straight rod portion and the second straight rod portion, and is equipped with a push chain that moves back and forth in the first direction and the second direction, a stage formed on the first straight rod portion and raised and lowered along the first direction by the forward and backward movement of the push chain, a guide that guides the forward and backward movement of the push chain at least at the first bent portion, and a sprocket that engages with the push chain on the side of the second straight rod portion closer to the first bent portion and drives the forward and backward movement of the push chain. Effect of the Invention

[0007] According to one aspect of the present invention, it is possible to design a lifting device that reduces the height of the lifting device in the lifting direction of the stage while reducing buckling of the push chain. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic enlarged view of a portion of a side surface of a lifting device according to a first embodiment of the present invention. [Diagram 2] 1 is a schematic side view of a transport platform vehicle according to a first embodiment of the present invention. [Diagram 3] 1 is a schematic side view of a lifting device according to a first embodiment of the present invention. [Figure 4] FIG. 11 is a schematic side view of a lifting device according to a comparative example. [Diagram 5] 13 is a schematic enlarged view of a portion of a side surface of a lifting device according to a comparative example. FIG. [Figure 6] FIG. 6 is a schematic side view of a lifting device according to a second embodiment of the present invention. [Figure 7] 10 is a schematic enlarged view of a portion of a side surface of a lifting device according to a second embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Embodiment 1] <Transport cart> 2 is a schematic side view for explaining the overall configuration of the transport vehicle according to this embodiment. In this embodiment, a transport vehicle having a function of transporting and lifting a vehicle body, which is used in a line for assembling parts to a vehicle body in an automobile production line, is taken as an example for explanation. However, the transport vehicle in this specification is not limited to this, and there is no particular restriction on the object to be transported and lifted, and a transport vehicle that transports and lifts the object may be realized by appropriately changing the member supporting the object.

[0010] As shown in Fig. 2, the transporting cart 2 according to this embodiment includes a lifting device 4, a floor 6, and wheels 8. The lifting device 4 is a device that supports, for example, a car body X shown in Fig. 2 and lifts and lowers it along a lifting direction DE by a method described later. The floor 6 is a platform on which a worker Y stands to perform work such as assembling parts on the car body X supported by the lifting device 4. The wheels 8 are, for example, wheels attached to the lower side of the floor 6 and driven to rotate by a drive unit (not shown) to move the floor 6 along the transporting direction DC. Note that the wheels 8 are not limited to the drive wheels described above, and may be driven wheels that rotate when the transporting cart 2 itself is pushed or pulled by an external force.

[0011] In this embodiment, the angle that the lifting direction DE forms with the vertical direction is smaller than the angle that the transport direction DC forms with the vertical direction. For example, the lifting direction DE is substantially the same as the vertical direction, and therefore the lifting device 4 lifts and lowers the car body X in a substantially vertical direction. In addition, the transport direction DC may be, for example, parallel to the ground surface that the wheels 8 contact, or may be substantially the same as the horizontal direction that is perpendicular to the vertical direction.

[0012] Furthermore, the wheels 8 may be formed on rails (not shown), in which case the conveying direction DC may be substantially the same as the extending direction of the rails, in other words, the transporting cart 2 may move along the rails. On the other hand, the wheels 8 may be formed on the lower end of a wheel support column 8A extending substantially vertically, and the wheels 8 may rotate around the wheel support column 8A. In this case, the transporting cart 2 may move freely on a certain flat surface such as the ground.

[0013] For example, as shown in FIG. 2, the lifting device 4 is supported on the lower side of the floor 6 by a floor support column 6A extending from below the floor 6. In other words, the lifting device 4 and the floor 6 are formed integrally. Therefore, when the floor 6 moves in the conveying direction DC by the rotation of the wheels 8, the lifting device 4 also moves in the conveying direction DC, and the vehicle body X supported by the lifting device 4 also moves in the conveying direction DC. Therefore, the transporting cart 2 can move both the vehicle body X supported by the lifting device 4 and the worker Y on the floor 6 in the conveying direction DC, while lifting and lowering the vehicle body X in the lifting and lowering direction DE by the lifting device 4. Therefore, the transporting cart 2 can transport the vehicle body X in the conveying direction DC, lift and lower the vehicle body X in the lifting and lowering direction DE, and allow the worker Y on the floor 6 to work on the vehicle body X.

[0014] The lifting and lowering of the vehicle body X by the lifting device 4 and the transportation of the vehicle body X by the rotational drive of the wheels 8 may be realized through control of the lifting device 4 by a control unit (not shown) and control of the drive unit of the wheels 8. The transporting cart 2 may be equipped with the above-mentioned control unit. Alternatively, the control unit may control each unit of the transporting cart 2 by transmitting control contents to the transporting cart 2 by a communication means (not shown).

[0015] <Overview of the lifting device> Next, the lifting device 4 provided in the transport cart 2 according to this embodiment will be described in more detail with reference to Fig. 3. Fig. 3 is a schematic side view for explaining the overall configuration of the lifting device 4 according to this embodiment and the lifting operation of the lifting device 4. Note that in Fig. 3, in order to illustrate each part of the lifting device 4 in more detail, some members of the lifting device 4, such as a link mechanism 24 and a link rail 26 described later, may be illustrated in a see-through manner.

[0016] 3 shows an ascending state 4U in which the lifting device 4 supports the vehicle body X above the lifting direction DE, and a descending state 4D in which the lifting device 4 supports the vehicle body X below the ascending state 4U in the lifting direction DE. Furthermore, FIG 3 shows an intermediate state 4M in which the lifting device 4 supports the vehicle body X between the ascending state 4U and the descending state 4D.

[0017] As shown in each drawing in FIG. 3, the lifting device 4 includes a push chain 10, a stage 12, a guide 14, a sprocket 16, a case 18, a chain support portion 20, a base portion 22, a link mechanism 24, and a link rail 26.

[0018] <Push Chain> Each part of the lifting device 4 will be described in more detail with reference to Fig. 1 together with Fig. 3. Fig. 1 is a schematic enlarged view showing some members of the lifting device 4 in an area A shown in an intermediate state 4M in Fig. 3. In particular, Fig. 1 is a schematic enlarged view showing only the push chain 10, the guide 14, the sprocket 16, and the chain support part 20 of the lifting device 4 around the guide 14 and the sprocket 16.

[0019] The push chain 10 is a roller chain that can be bent in only one direction from a state where it is aligned in a substantially straight line. For example, as shown in Figure 1, the push chain 10 is a roller chain in which multiple plates 30 are connected to both ends of multiple pins 28, and rollers 32 are fitted rotatably around each pin 28.

[0020] In particular, the plates 30 include an outer plate 30A and an inner plate 30B located on the inside of the outer plate 30 in the extension direction of the pin 28, and the outer plates 30A and the inner plates 30B are alternately connected to the pin 28. Here, each plate 30 includes an arched portion 30S and a rectangular portion 30R, and each plate 30 is connected with the sides on which the arched portion 30S and the rectangular portion 30R are formed aligned.

[0021] For example, at least one of the outer plate 30A and the inner plate 30B is formed to be rotatable with respect to the pin 28. Therefore, the push chain 10 is flexible in a direction perpendicular to both the longitudinal direction of the pin 28 and the connection direction of the push chain 10. However, due to interference between the rectangular portions 30R of the adjacent outer plates 30A or the rectangular portions 30R of the adjacent inner plates 30B, the push chain 10 is restricted from bending toward the rectangular portions 30R from a state in which the push chains 10 are aligned substantially in a straight line. In other words, the push chain 10 only bends toward the arched portion 30S from a state in which the push chains 10 are aligned substantially in a straight line.

[0022] In this embodiment, as shown in Figures 1 and 3, the push chain 10 includes a first straight rod portion 10A, a second straight rod portion 10B, and a first bent portion 10C between the first straight rod portion 10A and the second straight rod portion 10B. Here, in this specification, the "straight rod portion" of the push chain 10 refers to a portion where further bending toward the rectangular portion 30R is restricted. Also, in this specification, the "bent portion" of the push chain 10 refers to a portion including the plates 30 that are bent in the direction of the arched portion 30S from a state where the rectangular portions 30R are in contact with each other.

[0023] The first straight rod portion 10A is aligned along a first direction D1 shown in Fig. 1 and Fig. 3, and the second straight rod portion 10B is aligned along a second direction D2 shown in Fig. 1 and Fig. 3. In particular, the angle formed by the first direction D1 with the vertical direction is smaller than that formed by the second direction D2. As will be described in detail later, the push chain 10 moves forward and backward in the connecting direction as it is driven by the sprocket 16. Therefore, the push chain 10 moves forward and backward in the first direction D1 and the second direction D2. In particular, the first straight rod portion 10A moves forward and backward in the first direction D1, and the second straight rod portion 10B moves forward and backward along the second direction D2.

[0024] The push chain 10 according to this embodiment is not limited to the structure shown in Fig. 1. For example, the push chain 10 according to this embodiment can be any conventional push chain that is bent by a guide (described later) to form the first straight rod portion 10A and the second straight rod portion 10B.

[0025] <Stage> The stage 12 is a support part that supports the car body X, and is formed on the first straight rod part 10A, and is formed on the end part of the first straight rod part 10A opposite to the first bent part 10C via, for example, a fastener 12F such as a bolt and a nut. Therefore, the stage 12 rises and falls along the first direction D1 together with the car body X as the first straight rod part 10A advances and retreats along the first direction D1. Therefore, the lifting direction DE in which the transporting cart 2 raises and lowers the car body X is substantially the same as the first direction D1 in which the first straight rod part 10A advances and retreats. Since the angle that the first direction D1 makes with the vertical direction is smaller than that of the second direction D2, the lifting device 4 can be configured to be more suitable as a lifting mechanism for the transporting cart 2 when the first direction D1 is the lifting direction DE.

[0026] Therefore, as the push chain 10 moves from the first straight rod portion 10A side to the second straight rod portion 10B side, the stage 12 is pulled by the push chain 10 and descends downward in the first direction D1. For example, when the push chain 10 of the lifting device 4 in the raised state 4U moves from the first straight rod portion 10A side to the second straight rod portion 10B side, the movement of the push chain 10 and the descent of the stage 12 cause the lifting device 4 to transition to the lowered state 4D via the intermediate state 4M.

[0027] Furthermore, as the push chain 10 moves from the second straight rod portion 10B side to the first straight rod portion 10A side, the first straight rod portion 10A of the push chain 10 moves from above the guide 14 described below to further above it. Here, bending of the first straight rod portion 10A toward the rectangular portion 30R side is restricted, and bending toward the arched portion 30S side is also restricted by the link mechanism 24 described below. For this reason, the first straight rod portion 10A continues to move further above the guide 14 without bending, pushing up the stage 12.

[0028] Therefore, as the push chain 10 moves from the second straight rod portion 10B side to the first straight rod portion 10A side, the stage 12 is pushed out by the push chain 10 and rises upward in the first direction D1. For example, when the push chain 10 of the lifting device 4 in the lowered state 4D moves from the second straight rod portion 10B side to the first straight rod portion 10A side, as the push chain 10 moves and the stage 12 rises, the lifting device 4 transitions to the upper state 4U via the intermediate state 4M.

[0029] For example, an opening having a shape substantially the same as or larger than that of the stage 12 may be formed in the floor 6, and the stage 12 may pass through the opening and rise upward in the lifting direction DE. In addition, when the lifting device 4 is in the lowered state 4D, the upper surface of the stage 12 may be positioned on substantially the same plane as the upper surface of the floor 6.

[0030] <Guide> The guide 14 is a guide that guides the push chain 10 in the forward and backward directions in at least a part of the first straight rod portion 10A and at least a part of the first bent portion 10C. As shown in Fig. 1, the guide 14 includes a set of curved surface portions 34 that are curved toward the arched portion 30S side, and a set of flat surface portions 36 that are aligned along the first direction D1. The curved surface portions 34 sandwich and support the rollers 32 included in the first bent portion 10C of the push chain 10, and the flat surface portions 36 sandwich and support the rollers 32 included in the first straight rod portion 10A.

[0031] For example, the guide 14 includes a first guide 14A having one of the curved surface portion 34 and the flat surface portion 36, and a second guide 14B having the other of the curved surface portion 34 and the flat surface portion 36. In the first guide 14A and the second guide 14B, the curved surface portion 34 and the flat surface portion 36 may be formed continuously.

[0032] For example, when the push chain 10 moves toward the first straight rod portion 10A, the roller 32 located on the first bent portion 10C side of the second straight rod portion 10B is supported by the curved surface portion 34. Here, as the roller 32 is pressed by the curved surface portion 34 curved toward the arched portion 30S, the portion of the push chain 10 abutting against the curved surface portion 34 is bent toward the arched portion 30S to become the first bent portion 10C.

[0033] Furthermore, when the push chain 10 moves toward the first straight rod portion 10A, the roller 32 located on the first straight rod portion 10A side of the first bent portion 10C is clamped by the flat portion 36. Here, the portion of the push chain 10 where the roller 32 is clamped by the flat portion 36 along the first direction D1 is corrected in the direction along the first direction D1 to become the first straight rod portion 10A.

[0034] The guide 14 guides the moving direction of the push chain 10 by a set of curved surface portion 34 and flat surface portion 36 that sandwich and support the rollers 32 of the push chain 10. Therefore, the guide 14 can guide the push chain 10 without having a complex mechanism such as a rail that restrains the push chain 10. Therefore, the lifting device 4 according to this embodiment can simplify the guide 14.

[0035] For example, if the distance between adjacent pins 28 is the chain pitch CP, the distance R1 over which the flat portion 36 along the first direction D1 supports the push chain 10 is at least twice the chain pitch CP. As a result, the orientation of the first straight rod portion 10A in the first direction D1 is corrected by the flat portion 36 by a length at least twice the chain pitch CP. In this case, the guide 14 can reduce bending of the first straight rod portion 10A that leaves the flat portion 36 toward the arched portion 30S.

[0036] <Sprocket> The sprocket 16 has a structure in which, for example, a plurality of teeth 38T are formed around the periphery of a disk portion 38. The sprocket 16 rotates around the center of the disk portion 38 by a power unit (not shown). Furthermore, the teeth 38T of the sprocket 16 are inserted between the plurality of rollers 32 of the push chain 10, whereby the sprocket 16 engages with the push chain 10.

[0037] As a result, the sprocket 16 rotates around the center of the disk portion 38 while engaged with the push chain 10, causing the teeth 38T to push the rollers 32 and move the push chain 10 back and forth. Therefore, the sprocket 16 moves the push chain 10 back and forth, and in turn raises and lowers the stage 12 formed on the first straight rod portion 10A along the first direction D1.

[0038] The sprocket 16 engages with the push chain 10 on the second straight bar portion 10B side rather than the first bent portion 10C. In particular, in this embodiment, the sprocket 16 only engages with the second straight bar portion 10B. Therefore, the winding angle of the push chain 10 around the sprocket 16 is smaller than when the sprocket 16 engages with the first bent portion 10C. Therefore, with the above configuration, the lifting device 4 achieves a reduction in speed unevenness in the forward and backward movement of the push chain 10.

[0039] Furthermore, the sprocket 16 engages with the push chain 10 from above the push chain 10 in the first direction D1. Therefore, the dimension formed by the guide 14 and the sprocket 16 in the first direction D1 is the distance from the lower end of the guide 14 to the upper end of each of the guide 14 and the sprocket 16 that is located above the first direction D1. Therefore, compared to the case where the sprocket 16 engages with the push chain 10 from below the push chain 10 in the first direction D1, the dimension of the entire lifting device 4 in the first direction D1 can be reduced.

[0040] <Case and chain support> The case 18 is a storage section for storing a portion of the push chain 10, and as shown in FIG. 3, includes a set of curved sections 40 curved toward the arch-shaped section 30S, and a set of flat sections 42 extending along the second direction D2.

[0041] For example, as the push chain 10 continues to move further toward the second straight rod portion 10B, the roller 32 located at the end of the second straight rod portion 10B facing the case 18 is clamped by the curved portion 40. Here, as the roller 32 is clamped by the curved portion 40 that is curved toward the arched portion 30S, the portion of the push chain 10 that abuts against the curved portion 40 is bent toward the arched portion 30S. As a result, for example, as shown in the downward state 4D in FIG. 3, the push chain 10 forms a second bent portion 10D located on the opposite side of the second straight rod portion 10B from the first straight rod portion 10A.

[0042] Furthermore, as the push chain 10 continues to move further toward the second bent portion 10D, the roller 32 located at the end of the second bent portion 10D opposite the second straight rod portion 10B is supported by the flat portion 42. Here, the portion of the push chain 10 where the roller 32 is supported by the flat portion 42 along the second direction D2 is corrected in the direction along the second direction D2. As a result, for example, as shown in the downward state 4D in FIG. 4, the push chain 10 forms a third straight rod portion 10E located on the opposite side of the second bent portion 10D from the first straight rod portion 10A.

[0043] In particular, the third straight rod part 10E is aligned along a third direction that forms an angle with the second direction D2 that is smaller than the angle with the first direction D1. For example, the third straight rod part 10E may be aligned along the second direction D2 like the second straight rod part 10B, as shown in the downward state D4 in Fig. 4. In this case, the third straight rod part 10E moves parallel to the second straight rod part 10B and in the opposite direction to the second straight rod part 10B.

[0044] 3, a portion of the push chain 10 is stored in the case 18 in a bent state at the second bent portion 10D. Therefore, the lifting device 4 including the push chain 10 having the second bent portion 10D and the third straight rod portion 10E can reduce the dimension in a direction perpendicular to the lifting direction of the lifting device 4. Therefore, even when the push chain 10 is extended to extend the lifting distance of the stage 12 in the first direction D1, the lifting device 4 can reduce an increase in the dimension in the direction perpendicular to the lifting direction of the lifting device 4.

[0045] 1, the chain support part 20 has a flat part 44 that contacts the roller 32 of the second straight rod part 10B and supports the second straight rod part 10B. For example, the flat part 44 of the chain support part 20 may be formed continuously with the end part of the curved part 34 of the guide 14 on the second straight rod part 10B side and the curved part 40 of the case 18.

[0046] <Base and link mechanism> The base 22 has a generally flush upper surface that supports at least the guide 14, the case 18, and the chain support 20, and is formed below the stage 12 in the first direction D1. For example, the transport cart 2 includes the base 22 below the lifting direction DE of the floor 6. As shown in FIG. 2, the floor 6 may be formed integrally with the lifting device 4 by supporting the base 22 via floor support columns 6A.

[0047] Link mechanism 24 includes, for example, a first link beam 46 and a second link beam 48 that intersect with each other, and a link shaft 50 that rotatably constrains first link beam 46 and second link beam 48 with respect to each other. First link beam 46 is rotatably constrained to a first fixed shaft 12A formed on the lower surface of stage 12 and a first sliding shaft 22A formed on the upper surface of base 22. Second link beam 48 is rotatably constrained to a second sliding shaft 12B formed on the lower surface of stage 12 and a second fixed shaft 22B formed on the upper surface of base 22.

[0048] The link rails 26 are formed on the lower surface of the stage 12 and the upper surface of the base 22. The link rails 26 on the lower surface of the stage 12 restrain the second slide shaft 12B so as to be movable in the second direction D2. Moreover, the link rails 26 on the upper surface of the base 22 restrain the first slide shaft 22A so as to be movable in the second direction D2.

[0049] The first slide shaft 22A and the second slide shaft 12B move on the link rail 26 in the second direction D2 as the stage 12 moves up and down. Meanwhile, the first link beam 46 and the second link beam 48 are constrained in the second direction D2 by the first fixed shaft 12A and the second fixed shaft 22B, regardless of the advance and retreat of the push chain 10. Therefore, the first link beam 46 and the second link beam 48 of the link mechanism 24 rotate about their respective shafts as the push chain 10 moves up and down, and raise and lower the stage 12 while constraining it relative to the base 22.

[0050] In particular, the link mechanism 24 moves the stage 12 up and down only in the first direction D1 while restraining the stage 12 in the second direction D2 relative to the base 22. As a result, the stage 12 moves up and down only along the first direction D1 with almost no movement in the second direction D2. In addition, by restraining the stage 12 in the second direction D2, the link mechanism 24 reduces bending of the first straight rod portion 10A of the push chain 10.

[0051] For example, the lifting device 4 may include a plurality of link mechanisms 24. For example, in Figures 2, 3, etc., another link mechanism 24 may be formed on the nearer side of the illustrated link mechanism 24 toward the paper surface. In this case, Figures 2, 3, etc. illustrate each part of the lifting device 4 through the nearer link mechanism 24 and link rails 26, etc.

[0052] 1, the heights in the first direction D1 from the lower end to the upper end of the guide 14 and from the lower end of the chain support part 20 to the upper end of the sprocket 16 are defined as height H14 and height H16, respectively. Here, the guide 14 and the chain support part 20 are disposed on the upper surface of the base part 22, which is substantially flush with one another. Therefore, low heights H14 and height H16 respectively indicate that the heights of the guide 14 and the sprocket 16 in the first direction D1 in the lifting device 4 are low.

[0053] As is clear from FIG. 1, the height H16 is lower than the height H14. In other words, the height of the sprocket 16 in the first direction D1 according to this embodiment is equal to or less than the height of the guide 14 in the first direction D1. Therefore, the sprocket 16 can reduce the dimension of the entire lifting device 4 in the first direction D1. However, as is clear from the lowered state 4D in FIG. 3, the diameter of the sprocket 16 can be increased without increasing the dimension of the entire lifting device 4 in the first direction D1 as long as it does not abut against the lower surface of the stage 12 in the most lowered state. The large diameter of the sprocket 16 can reduce the torque required to drive the sprocket 16. When the diameter of the sprocket 16 is increased, the power unit that drives the sprocket 16 may also be increased to the extent that it does not abut against the lower surface of the stage 12.

[0054] 3, the height from the bottom end to the top end of the case 18 in the first direction D1 is defined as height H18. Here, the case 18 is also disposed on the top surface of the base 22, which is substantially flush with the case 18. Therefore, a low height H18 means that the height of the case 18 in the first direction D1 in the lifting device 4 is low.

[0055] 3, height H18 is lower than height H14. In other words, in this embodiment, the height of the upper surface of case 18 in first direction D1 is lower than the height of the upper surface of guide 14. Therefore, case 18 can reduce the dimension of the entire lifting device 4 in the first direction D1.

[0056] <Lifting device according to comparative example> The effects of the lifting device 4 according to this embodiment will be described in comparison with a lifting device according to a comparative embodiment. First, the lifting device according to the comparative embodiment will be described with reference to Figs. 4 and 5. Fig. 4 is a schematic side view for explaining the overall configuration of the lifting device 4A according to the comparative embodiment and the lifting operation of the lifting device 4A. Fig. 5 is a schematic enlarged view of region B shown in Fig. 4, showing only the push chain 10, the guide 14C, the sprocket 16, and the chain support portion 20 of the lifting device 4A.

[0057] The lifting device 4A of the comparative embodiment differs from the lifting device 4 of this embodiment only in that it has a guide 14C instead of guide 14, the sprocket 16 engages with the first bent portion 10C, and it does not have a case 18.

[0058] 5, in the comparative embodiment, only the first guide 14A has a curved portion 34 and a flat portion 36, and the second guide 14B has only a flat portion 36 that faces the flat portion 36 of the first guide 14A. Also, in the comparative embodiment, the sprocket 16 engages with the first bent portion 10C, and in particular, the roller 32 of the first bent portion 10C is supported by the curved portion 34 of the first guide 14A and the sprocket 16.

[0059] In the comparative embodiment, the sprocket 16 engages with the first bent portion 10C, so that the first straight rod portion 10A guided by the guide 14C approaches the sprocket 16. For this reason, in the comparative embodiment, the position where the second guide 14B is formed needs to be moved above the sprocket 16 so that the second guide 14B, which has the flat portion 36 that supports the roller 32 of the first straight rod portion 10A, does not interfere with the sprocket 16.

[0060] As described above, in order to sufficiently reduce buckling of the first straight rod portion 10A, the distance R1 along the first direction D1 of the flat portion 36 that supports the rollers 32 of the first straight rod portion 10A needs to be at least twice the chain pitch CP. For this reason, while moving the second guide 14B above the sprocket 16, the height of the guide 14C in the first direction D1 increases in order to ensure the distance R1 along the first direction D1 of the flat portion 36.

[0061] 5, the height from the lower end to the upper end of the guide 14C in the first direction D1 is defined as height H14C. Here, the guide 14C is also disposed on the upper surface of the base 22, which is substantially flush with the guide 14C. Therefore, a low height H14C means that the height of the guide 14C in the first direction D1 in the lifting device 4A is low.

[0062] In the comparative embodiment, as described above, the position where the flat portion 36 of the guide 14C is formed is moved upward in the first direction D1 of the lifting device 4A. Therefore, the height H14C is higher than the height H14. In other words, the height in the first direction D1 of the guide 14C according to the comparative embodiment is higher than the height in the first direction D1 of the guide 14 according to the embodiment.

[0063] Therefore, the lifting device 4A according to the comparative embodiment has an increased height in the first direction D1 as an entire device. Accordingly, the lifting device 4A according to the comparative embodiment becomes larger in size in the first direction D1, and the lifting distance of the stage 12 is shortened by the increase in the height of the guide 14C in the first direction D1.

[0064] For example, when the transporting cart 2 is equipped with the lifting device 4A according to the comparative embodiment, the height of the floor 6 of the transporting cart 2 in the lifting direction DE increases by an amount corresponding to an increase in the height of the lifting device 4A in the first direction D1, which increases the burden on the worker Y who ascends and descends the floor 6. In addition, as the height of the floor 6 of the transporting cart 2 in the lifting direction DE increases, the space on the floor 6 for assembling parts to the vehicle body X, etc. is reduced.

[0065] In order to configure the transport cart 2 equipped with the lifting device 4A without increasing the height of the floor 6, it is necessary to protrude upward only the portion of the stage 12 that overlaps with the guide 14C in a plan view. For this reason, the lifting device 4A according to the comparative embodiment requires a complex design to realize a low floor of the floor 6.

[0066] Furthermore, since the lifting device 4A according to the comparative embodiment does not include the case 18, the second bent portion 10D and the third straight rod portion 10E are not formed in the push chain 10. Therefore, the lifting device 4A needs to make all of the push chain 10 that moves onto the chain support portion 20 as the stage 12 descends into the second straight rod portion 10B.

[0067] Therefore, in the lifting device 4A, the distance in the second direction D2 of the chain support part 20 required to align all the second straight rod parts 10B on the chain support part 20 when the stage 12 is located at the lower end is extended. Therefore, the lifting device 4A also extends the length of the chain support part 20 required with the extension of the push chain 10, so the dimension of the entire device in the second direction D2 becomes huge.

[0068] <Effects of the lifting device according to this embodiment> In the lifting device 4 according to this embodiment, the sprocket 16 engages with the push chain 10 on the second straight rod portion 10B side of the first bent portion 10C. Therefore, in the lifting device 4, the distance between the sprocket 16 and the first straight rod portion 10A is increased, and interference between the sprocket 16 and the second guide 14B forming the flat portion 36 that supports the rollers 32 of the first straight rod portion 10A is reduced.

[0069] Therefore, the lifting device 4 has improved freedom in the position of the second guide 14B that forms the flat surface portion 36, and can be designed to reduce the height of the guide 14 in the first direction D1. For example, by ensuring a sufficient distance between the sprocket 16 and the first straight rod portion 10A, the second guide 14B according to this embodiment can have the flat surface portion 36 that is continuous with the curved surface portion 34.

[0070] Therefore, with the above configuration, the lifting device 4 according to this embodiment can reduce the height of the guide 14 in the first direction D1 without requiring a complex design, and can therefore reduce the height of the entire device in the first direction D1. The transporting cart 2 equipped with the lifting device 4 according to this embodiment can achieve a low floor of the floor section 6 without requiring a complex design. Therefore, the transporting cart 2 simplifies the structure of the transporting cart 2, reduces the burden on the worker Y when ascending and descending the floor section 6, and can ensure a larger space above the floor section 6.

[0071] Furthermore, the lifting device 4 according to this embodiment can store a part of the push chain 10 that moves onto the chain support part 20 as the stage 12 descends as the second bent part 10D and the third straight rod part 10E in the case 18. Therefore, compared to the lifting device 4A according to the comparative embodiment, the lifting device 4 according to this embodiment reduces the extension of the length of the chain support part 20 that is required as the push chain 10 extends, and therefore reduces the enlargement of the dimensions of the entire device in the second direction D2. As described above, when considering that the lifting device 4 according to this embodiment can reduce the height of the entire device in the first direction D1, the lifting device 4 can reduce the dimensions in both the lifting direction and the directions different from the lifting direction.

[0072] In addition, the lifting device 4 may be configured to push and pull the push chain 10 by a separate power unit at the end of the push chain 10 instead of the sprocket 16. Here, in the lifting device 4 according to this embodiment, the push chain 10 is bent at the second bent portion 10D, and the third straight rod portion 10E is positioned above the second straight rod portion 10B. Therefore, for example, the lifting device 4 may be configured to push and pull the push chain 10 by the power unit at the end of the push chain 10, which means that the end of the third straight rod portion 10E is pushed and pulled by the power unit. In this configuration, the power unit must also be positioned above the second straight rod portion 10B, which increases the height of the entire device in the first direction D1.

[0073] The lifting device 4 according to this embodiment includes a sprocket 16 that engages with the second straight rod portion 10B to drive the forward and backward movement of the push chain 10. Therefore, compared to a configuration in which the push chain 10 is pushed and pulled by the above-mentioned power portion at the end of the push chain 10, the lifting device 4 according to this embodiment can reduce an increase in the height of the entire device in the first direction D1.

[0074] [Embodiment 2] <Lifting device according to another embodiment> Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0075] The transporting cart 2 according to this embodiment differs from the transporting cart 2 according to the previous embodiment in configuration only in that it includes a lifting device 52 instead of the lifting device 4. The lifting device 52 according to this embodiment will be described in detail with reference to Figs. 6 and 7.

[0076] Fig. 6 is a schematic side view for explaining the overall configuration of the lifting device 52 according to this embodiment and the lifting operation of the lifting device 52. In Fig. 6, some members of the lifting device 4 may be shown in a see-through manner, as in Fig. 3. In Fig. 6, the lifting device 52 is shown in an elevated state 52U, an intermediate state 52M, and a lowered state 52D, as in Fig. 3. Fig. 7 is a schematic enlarged view of the region C shown in Fig. 6, showing only the push chain 10, the guide 14, the sprocket 16, and the case 54, which will be described later, of the lifting device 4.

[0077] Compared to the lifting device 4 according to the previous embodiment, the lifting device 52 according to this embodiment has a case 54 instead of the case 18, and does not have the chain support portion 20. The case 54 stores the second straight rod portion 10B in addition to the second bent portion 10D and the third straight rod portion 10E described above. Therefore, the case 54 further has a pair of flat portions 56 that support the rollers 32 of the second straight rod portion 10B.

[0078] Also, compared to the case 18, the case 54 has a set of flat portions 42 that sandwich the rollers 32 of the third straight rod portion 10E, but has only one curved portion 40, and does not sandwich the rollers 32 of the second bent portion 10D by the set of curved portions 40. Instead, in the lifting device 52 according to this embodiment, the sprocket 16 engages with the second bent portion 10D. Therefore, the rollers 32 of the second bent portion 10D are sandwiched between the curved portion 40 of the case 54 and the sprocket 16.

[0079] Since the sprocket 16 engages with the second bent portion 10D, the wrap angle of the push chain 10 around the sprocket 16 in this embodiment is increased compared to the wrap angle of the push chain 10 around the sprocket 16 in the previous embodiment. Therefore, in this embodiment, the number of teeth 38T that engage with the push chain 10 is increased compared to the previous embodiment.

[0080] As a result, the lifting device 52 can more efficiently transmit the force for rotating the push chain 10 to the force for moving the push chain 10 back and forth, reducing misalignment between the push chain 10 and the sprocket 16. Furthermore, the lifting device 52 can more efficiently maintain the sprocket 16 not to rotate in response to the force that rotates the sprocket 16 transmitted from the push chain 10 due to the load of the vehicle body X or the like on the stage 12. Therefore, the lifting device 52 can increase the load capacity of the stage 12.

[0081] Except for the above points, the lifting device 52 according to this embodiment has the same configuration as the lifting device 4 according to the previous embodiment. Therefore, in the lifting device 52 according to this embodiment, like the lifting device 4 according to the previous embodiment, the sprocket 16 engages with the push chain 10 on the side of the second straight rod portion 10B rather than the first bent portion 10C.

[0082] Therefore, for the same reasons as those described for the lifting device 4 according to the previous embodiment, the lifting device 52 according to this embodiment can be designed to reduce the height of the entire device in the first direction D1 without requiring a complex design. The transport cart 2 equipped with the lifting device 52 according to this embodiment simplifies the structure of the transport cart 2, reduces the burden on the worker Y when ascending and descending the floor part 6, and also ensures a larger space above the floor part 6.

[0083] 7, the height from the bottom end to the top end of the case 54 in the first direction D1 is defined as height H54. Here, the case 54 is also disposed on the upper surface of the base 22, which is substantially flush with the case 54. Therefore, a low height H54 means that the height of the case 54 in the first direction D1 in the lifting device 4 is low.

[0084] 7, the height H54 is higher than the height H14, which is the height of the guide 14 in the first direction D1. Here, for example, by designing the bendable angle of the push chain 10 to be larger and by reducing the diameter of the sprocket 16, the height of the case 54 in the first direction D1 can be designed to be lower. Therefore, for example, by making the height H54 lower than the height H14, the height of the entire lifting device 4 in the first direction D1 can be reduced.

[0085] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0086] 2 Transport cart 4, 52 Lifting device 6 Floor 10 Push Chain 10A 1st straight rod section 10B 2nd straight bar part 10C 1st bending part 10D 2nd bending part 10E 3rd straight rod section 12 Stages 14 Guide 16 Sprockets 18, 54 cases

Claims

1. a push chain having a first straight rod portion along a first direction, a second straight rod portion along a second direction different from the first direction, and a first bent portion between the first straight rod portion and the second straight rod portion, the push chain moving forward and backward in the first direction and the second direction; a stage formed on the first straight rod portion and raised and lowered along the first direction by the forward and backward movement of the push chain; a guide that guides the advancement and retreat of the push chain in at least a portion of the first straight rod portion and at least a portion of the first bent portion; a sprocket that engages with the push chain only on the side of the second straight rod portion relative to the first bent portion in the connection direction of the push chain, and drives the forward and backward movement of the push chain.

2. 2. The lifting device according to claim 1, wherein the sprocket engages with the push chain from a side closer to the stage than the push chain.

3. The lifting device according to claim 1 or 2, wherein the first direction forms an angle with a vertical direction smaller than an angle with the second direction.

4. The lifting device according to any one of claims 1 to 3, wherein a length along the first direction of a portion of the guide that clamps the first straight rod portion is at least twice the chain pitch of the push chain.

5. The lifting device according to any one of claims 1 to 4, wherein the guide has a pair of curved portions that sandwich the first bent portion, and a pair of flat portions that sandwich the first straight rod portion and extend along the first direction.

6. The lifting device according to claim 1 , wherein a height of the sprocket in the first direction is equal to or less than a height of the guide in the first direction.

7. Further comprising a case for accommodating at least the second straight rod portion, The lifting device according to claim 1 , wherein a height of the case in the first direction is equal to or less than a height of the guide in the first direction.

8. The lifting device according to any one of claims 1 to 7, wherein the push chain further includes a third straight rod portion located on the opposite side of the first straight rod portion from the second straight rod portion in the connection direction of the push chain and extending along a third direction in which the angle it forms with the second direction is smaller than the angle it forms with the first direction, and a second bent portion located between the second straight rod portion and the third straight rod portion in the connection direction of the push chain.

9. The lifting device according to claim 1 , wherein the sprocket engages only with the second straight rod portion.

10. 9. The lifting apparatus of claim 8, wherein the sprocket engages only the second bend.

11. The lifting device according to any one of claims 1 to 10, The transport vehicle has an angle that the first direction forms with the vertical direction smaller than an angle that the transport direction forms with the vertical direction.

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