JP7779287B2 - Pallet lifting device, transport device - Google Patents

Description

This disclosure relates to a pallet lifting device that raises and lowers pallets loaded with cargo, and a conveying device that is equipped with the pallet lifting device and that transports cargo by transporting pallets.

Patent Document 1 describes a conveying device that conveys carts (pallets) along guide rails, and describes a descending path section and an ascending path section for transporting carts between a conveying path section and a return path section located above and below each other.

JP 2015-193480 A

When a conveying device is equipped with a mechanism for raising and lowering pallets, such as the ascending path section described in Patent Document 1, the mechanism cannot load pallets until it returns to a position where it can receive the pallets after raising and lowering the pallets. For this reason, the conveying device requires time to transport multiple pallets up and down.

A pallet lifting device according to one aspect of the present disclosure is a pallet lifting device that raises or lowers a pallet fed at a first height to a second height before feeding it out. The device includes a plurality of support parts for supporting and raising or lowering the pallet, each of which has an arm that extends in a direction perpendicular to a first axis, which is a horizontal axis, and rotates around the first axis located in the center of the arm's longitudinal direction, and a pair of rollers provided on both ends of the arm, and each of the rollers is configured so that the roller axis is perpendicular to a second axis along the longitudinal direction of the arm and parallel to the first axis, allowing the roller to assume a first position for supporting the pallet.

A pallet lifting device that can simultaneously support a fed pallet and deliver other pallets that have been lifted or lowered.

1 is an enlarged perspective view of a conveying device according to a first embodiment of the present disclosure, and an enlarged perspective view of a support portion. FIG. 1A and 1B are a schematic perspective view, a schematic plan view, and a schematic side view of a conveying device according to a first embodiment of the present disclosure. FIG. 10 is an enlarged perspective view of a support portion in which one of the rollers according to the first embodiment of the present disclosure is in a second position. 2A and 2B are a schematic side view and a schematic plan view of a portion of a support part according to the first embodiment of the present disclosure. 10 is a schematic diagram of a part of a support portion and a part of an auxiliary roller guide showing how the roller according to the first embodiment of the present disclosure transitions from a first position to a second position. FIG. 10 is a schematic diagram of a part of the support portion and a part of the auxiliary roller guide showing the transition of the roller from the second position to the first position according to the first embodiment of the present disclosure. FIG. 10 is a side view of a part of the process of the transport unit, return unit, and pallet lifting device in the transfer of a pallet between the transport section or return section and the pallet lifting device according to the first embodiment of the present disclosure. FIG. 2 is a schematic side view of each drive roller and each pallet, illustrating the positional relationship between each drive roller and each pallet of the pallet lifting device according to the first embodiment of the present disclosure. FIG. 1 is an enlarged perspective view of a pallet lifting device showing an example in which a plurality of support parts are connected by a belt according to the first embodiment of the present disclosure. FIG. FIG. 10 is an enlarged perspective view of a support part according to a second embodiment of the present disclosure. FIG. 10 is an enlarged side view of one of the support parts and a portion of the pallet when the pallet is being supported and raised and lowered by a pallet lifting device according to a second embodiment of the present disclosure. 10A and 10B are enlarged perspective views of a conveying device and a support portion according to a third embodiment of the present disclosure; FIG. 10 is an enlarged side view of a portion of a pallet lifting device and a pallet in a state in which the pallet is being supported and lifted by the pallet lifting device according to a third embodiment of the present disclosure.

[Embodiment 1]
<Transportation equipment: Overview>
In this embodiment, a conveying device that conveys cargo by conveying a pallet loaded with cargo along a fixed route will be described. In particular, the conveying device according to this embodiment is a conveying device that loads a vehicle body such as an automobile on a pallet and conveys the vehicle body. The conveying device according to this embodiment will be described with reference to FIG. 2.

Figure 2 shows a schematic perspective view 202, a schematic plan view 204, and a schematic side view 206 of the conveying device 2 according to this embodiment. Figure 2 also shows the vehicle body X that is conveyed by the conveying device 2. Note that the schematic plan view 204 and the schematic side view 206 show enlarged views of the vicinity of the descending section 10 and the ascending section 12, which will be described later, and omit a portion of the conveying device 2 that is shown in its entirety in the schematic perspective view 202.

The conveying device 2 includes a pallet 4, a conveying section 6, a return section 8, a lowering section 10, and an ascending section 12. The conveying device 2 conveys the pallet 4 along a fixed path using the conveying section 6, the return section 8, the lowering section 10, and the ascending section 12. The conveying device 2 also conveys the vehicle body X by using the conveying section 6 to transport the pallet 4 carrying the vehicle body X, using a method described below.

<Transportation device: pallet>
The pallet 4 is, for example, a plate-like member having a plurality of treads fitted into openings in a frame body. For example, the pallet 4 may be configured so that the vehicle body X is held by a jig attached to the frame body, and a worker or the like can move onto the treads to perform work such as assembling parts to the vehicle body X.

<Transportation device: transport unit>
The conveying unit 6 conveys the pallet 4 in the conveying direction DT along a conveying path 6W extending in the conveying direction DT. The conveying device 2 loads the vehicle body X on the pallet 4 and conveys the pallet 4 in the conveying direction DT using the conveying unit 6, thereby conveying the vehicle body X in the conveying direction DT. The conveying unit 6 includes, for example, a plurality of conveying units 6U arranged in the conveying direction DT. The conveying unit 6 transports the pallet 4 in the conveying direction DT by repeatedly transferring the pallet 4 from one conveying unit 6U to an adjacent conveying unit 6U in the conveying direction DT.

A vehicle body X transported by an input device (not shown) is loaded onto a pallet 4 located at the start of the conveying path 6W. A vehicle body X is removed from the pallet 4 located at the end of the conveying path 6W by an unloading device (not shown). A pallet 4 without a vehicle body X is transported to the start of the conveying path 6W using a method described below. The conveying device 2 may, for example, sequentially transport pallets 4 loaded with vehicle bodies X at the start of the conveying path 6W using the conveying unit 6. Using this method, the conveying device 2 may simultaneously transport multiple vehicle bodies X using the conveying unit 6. As described above, a worker may transfer onto the pallet 4 being transported by the conveying unit 6, and the worker may perform work such as assembling parts onto the transported vehicle body X.

<Conveyor device: Return section>
The return unit 8 transports the pallets 4 in the return direction DR along a return path 8W that extends in the return direction DR, which is the opposite direction to the conveying direction DT. For example, the return path 8W is located below the conveying path 6W, and at least a portion of it overlaps with the conveying path 6W in a plan view. Therefore, one of the conveying unit 6 and the return unit 8 transports the pallets 4 at a first height, and the other of the conveying unit 6 and the return unit 8 transports the pallets 4 at a second height.

The conveying device 2 transports the pallets 4 upstream along the return path 8W by using the return section 8 to transport the pallets 4 in the return direction DR. The return section 8, for example, includes multiple return units 8U arranged in the return direction DR. The return section 8 transports the pallets 4 in the return direction DR by repeatedly transferring the pallets 4 from one return unit 8U to an adjacent return unit 8U in the return direction DR.

<Conveyor device: descending section, ascending section>
The lowering unit 10 lowers the pallet 4 that has been transported to the end of the transport path 6W, and transfers the pallet 4 from the end of the transport path 6W to the start of the return path 8W. The ascending unit 12 raises the pallet 4 that has been transported to the end of the return path 8W, and transfers the pallet 4 from the end of the return path 8W to the start of the transport path 6W. In this way, the transport device 2 circulates the pallets 4 using the transport unit 6, the return unit 8, the lowering unit 10, and the ascending unit 12.

The descending section 10 includes a pallet lifting device 24 adjacent to the transport unit 6U located at the end of the transport path 6W and the return unit 8U located at the start of the return path 8W. The ascending section 12 also includes a pallet lifting device 24 adjacent to the transport unit 6U located at the start of the transport path 6W and the return unit 8U located at the end of the return path 8W. The descending section 10 and the ascending section 12 may be equipped with pallet lifting devices 24 of the same configuration, except for the method of controlling the attitude of the rollers 42, which will be described later.

<Transportation device: transport unit and return unit>
The conveying section 6, the returning section 8, and the pallet lifting device 24 will be described in more detail with reference to Fig. 1. Fig. 1 shows an enlarged perspective view 102 of a portion of the conveying device 2 and an enlarged perspective view 104 of a support section 32, which is part of the pallet lifting device 24 and will be described later.

The enlarged perspective view 102 is an enlarged perspective view showing, in particular, the pallet lifting device 24 provided in the ascending section 12 of the conveying device 2, and the transport unit 6U and return unit 8U adjacent to the pallet lifting device 24. Each of the conveying section 6 and the return section 8 may be provided with multiple transport units 6U and return units 8U having the same configuration as the transport unit 6U and return unit 8U shown in the enlarged perspective view 102. The descending section 10 may also be provided with a pallet lifting device 24 having the same configuration as the pallet lifting device 24 shown in the enlarged perspective view 102.

The transport unit 6U of the transport section 6 has rails 26, rollers 28, and a friction drive unit 30. The rails 26 are arranged along the transport direction DT. The transport unit 6U has two rails 26 arranged at a distance from each other in a direction perpendicular to the transport direction DT and the up-down direction. A plurality of rollers 28 are formed on each rail 26 along the transport direction DT. The rollers 28 are arranged on each rail 26 so that the rollers 28 of the two rails 26 face each other.

A friction drive unit 30 is disposed on each of the two rails 26. Each friction drive unit 30 has a drive roller 30R with a vertical rotation axis. The two drive rollers 30R are disposed so that the pallet 4 being transported is located between them. In particular, the two drive rollers 30R are disposed so that they sandwich the pallet 4 from the sides and rub against each other's side surfaces.

The rollers 28 are rotatably constrained to a rotation axis extending in a direction perpendicular to the conveying direction DT and the vertical direction. The conveying unit 6U supports the pallet 4 on the rollers 28 by placing the pallet 4 on each of the rollers 28 on the two rails 26.

In this state, the friction drive unit 30 of the transport unit 6U rotates the two drive rollers 30R around their rotation axes while clamping the pallet 4 between them. As a result, the friction drive unit 30 sends the pallet 4 clamped between the two drive rollers 30R in the transport direction DT. Here, friction between each roller 28 and the pallet 4 it supports causes each roller 28 to rotate around its rotation axis. In this way, the transport unit 6U transports the pallet 4 supported by the rollers 28 along the transport path 6W in the transport direction DT.

The return unit 8U of the return section 8 is located below the transport unit 6U and has the same configuration as the transport unit 6U, except that the rotation direction of each drive roller 30R is opposite. Therefore, the return unit 8U transports the pallet 4 supported by the rollers 28 in the return direction DR along the return path 8W. The transport unit 6U and the return unit 8U may be formed as a single unit by fixing their rails 26 to each other.

<Pallet lifting device: Overview>
As shown in enlarged perspective view 102, pallet lifting device 24 includes a plurality of support portions 32 and a plurality of friction drive units 30. The friction drive units 30 included in pallet lifting device 24 may be the same as the friction drive units 30 included in transport unit 6U and return unit 8U.

The pallet lifting device 24 provided in the lowering section 10 lowers the pallet 4 sent from the conveying section 6 and sends it to the return section 8. The pallet lifting device 24 provided in the ascending section 12 raises the pallet 4 sent from the return section 8 and sends it to the conveying section 6. In other words, the pallet lifting device 24 is a device that raises or lowers the pallet 4 sent at a first height to a second height and then sends it out.

In particular, the pallet lifting device 24 supports and raises and lowers the pallets 4 sent from the conveying section 6 or the return section 8 using multiple support sections 32, and sends them out to the conveying section 6 or the return section 8. The reception of the pallets 4 sent from the conveying section 6 or the return section 8 and the sending out of the pallets 4 to the conveying section 6 or the return section 8 are performed by the friction drive unit 30.

The friction drive unit 30 provided in the pallet lifting device 24 drives the pallet 4 by, for example, rotating the two drive rollers 30R included in the friction drive unit 30 while the pallet 4 is sandwiched between them, as described above.

In particular, in this embodiment, the friction drive unit 30 provided in the pallet lifting device 24 includes a drive roller 30R as a first drive roller that drives the pallet 4 fed from either the conveying section 6 or the return section 8. The friction drive unit 30 provided in the pallet lifting device 24 also includes a drive roller 30R as a second drive roller that drives the pallet 4 fed from the other of the conveying section 6 or the return section 8.

The pallet lifting device 24 has multiple pairs of support parts 32 that face each other in a direction perpendicular to the transport direction DT of the pallet 4 and the up-down direction. Furthermore, the multiple pairs of support parts 32 are aligned in approximately the same direction as the transport direction DT of the pallet 4. The pairs of support parts 32 are arranged so that the sides of the rollers 42, which will be described later, face each other. Each support part 32 is arranged so that, in a plan view, the pallet 4 fed into the pallet lifting device 24 by the method described later overlaps only the rollers 42 and roller shafts 44, which will be described later.

Hereinafter, unless otherwise specified, the pallet lifting device 24 in this embodiment refers to the pallet lifting device 24 provided in the lifting section 12.

<Pallet lifting device: Support part: Overview>
The support portion 32 will be described in more detail with reference to an enlarged perspective view 104 of the support portion 32. Note that in order to more simply and clearly describe each part of the support portion 32, some of the members included in the support portion 32 may be omitted in the drawings including FIG.

The support unit 32 has a shaft 34 extending along a first horizontal axis, a shaft bearing 36 that constrains the shaft 34 so that it can rotate around its longitudinal axis, and a shaft drive unit 38 that has a motor or the like that drives the rotation of the shaft 34. The shaft 34 extends in a direction perpendicular to the conveying direction DT and the vertical direction. The shaft bearing 36 is fixed, for example, via bolts 36B or the like to a base (not shown) that is fixed to the ground. As a result, the shaft 34 is driven by the shaft drive unit 38 and can rotate in a direction perpendicular to the conveying direction DT and the vertical direction, while its position is fixed relative to the ground.

<Pallet lifting device: support part: arm and roller>
Furthermore, the support unit 32 has an arm 40 fixed to the end of the shaft 34 on the conveying path 6W side, and a pair of rollers 42 provided on both ends of the arm 40. In this embodiment, the support unit 32 has a pair of roller shafts 44 which are rotation axes of the rollers 42, and roller shaft support units 46 on which the roller shafts 44 are formed and which are formed on both ends of the arm 40.

The arm 40 extends in both the direction of extension of the shaft 34 and the direction perpendicular to it. Therefore, the shaft 34 is located at the longitudinal center of the arm 40, and the arm 40 rotates around the extension direction of the shaft 34 as the shaft 34 rotates. Note that the enlarged oblique view 104 shows the support part 32 in a state in which the arm 40 extends in the vertical direction.

Each roller 42 is constrained to be rotatable around a roller axis 44. Each roller axis 44 is perpendicular to a second axis along the longitudinal direction of the arm 40. Each roller axis support 46 is constrained to the arm 40 so as to be rotatable around the longitudinal direction of the arm 40. Therefore, the roller axis 44 of each roller 42 is rotatable around the arm 40, and therefore each roller 42 is also rotatable around the arm 40.

In this embodiment, each roller 42 is a driven roller that rotates around its roller shaft 44 due to an external force. For example, each roller 42 rotates around its roller shaft 44 due to friction with the pallet 4, which is transported using a method described below. Note that while some of the rollers 42 may be drive rollers, from the perspective of reducing the number of drive units required to rotate the rollers 42, all of the rollers 42 may be driven rollers.

For example, the support unit 32 has two rollers 42: roller 42A that rotates around roller shaft 44A and roller 42B that rotates around roller shaft 44B. In particular, the enlarged perspective view 104 shows the support unit 32 in a state where roller 42A is located at the upper end of the arm 40 and roller 42B is located at the lower end of the arm 40. The support unit 32 also has two roller shaft support units 46: roller shaft support unit 46A where roller shaft 44A is formed, and roller shaft support unit 46B where roller shaft 44B is formed.

As the arm 40 rotates around the shaft 34, the two rollers 42 revolve around the first axis, in other words, around the longitudinal extension of the shaft 34. For example, in this embodiment, the support unit 32 shown in the enlarged oblique view 104 rotates the shaft 34 counterclockwise when viewed in the direction from the rollers 42 to the shaft 34 using the shaft drive unit 38. As a result, the two rollers 42 revolve counterclockwise around the first axis when viewed in the direction from the rollers 42 to the shaft 34.

<Pallet lifting device: support part: roller position>
Here, the enlarged perspective view 104 shows the state in which the two rollers 42 are in the first position. When the rollers 42 are in the first position, the roller axes 44 of the rollers 42 are parallel to the first axis, in other words, parallel to the extension direction of the shaft 34. The rollers 42 in the first position always maintain the first position regardless of the rotation of the arm 40 around the shaft 34, unless they rotate around the extension direction of the arm 40.

Furthermore, each roller 42 can assume a second position in which the roller shaft 44 rotates together with the roller shaft support portion 46 from the first position around the second axis, in other words, around the extension direction of the arm 40. The rollers 42 in the second position will be described in detail with reference to Figure 3. Figure 3 is another enlarged perspective view of the support portion 32, showing the support portion 32 from the same direction as the enlarged perspective view 104.

Figure 3 shows the support portion 32 in a state in which the arm 40 has rotated around the shaft 34 from a state in which it extends vertically. Therefore, of the two rollers 42, roller 42A has moved downward from the state shown in Figure 1, and roller 42B has moved upward from the state shown in Figure 1. Furthermore, as the roller shaft support portion 46A rotates around the arm 40, roller 42A shown in Figure 3 assumes a second position in which the roller shaft 44A has rotated around the arm 40, while roller 42B maintains its first position. In particular, in this embodiment, roller 42A in the second position is positioned higher on the opposite side than on the arm 40 side. The second position of roller 42A may be a position in which the roller shaft 44A has rotated about the arm 40 by approximately 90 degrees from the first position.

<Pallet lifting device: support part: auxiliary roller>
The change in the position of the roller 42 according to this embodiment is realized by an auxiliary roller 48 and an auxiliary roller guide (not shown in FIGS. 1 and 3) that the support portion 32 has.

The auxiliary rollers 48 include a first auxiliary roller 50 and a second auxiliary roller 52, which are constrained by the roller shaft support parts 46 so as to be rotatable around the extension direction of the arm 40. Therefore, as the roller shaft support parts 46 rotate around the arm 40, the first auxiliary roller 50 and the second auxiliary roller 52 revolve around the arm 40 in conjunction with the roller shaft 44. The first auxiliary roller 50 may be formed directly on the roller shaft support part 46, and the second auxiliary roller 52 may be formed on the roller shaft support part 46 via the auxiliary roller support part 48S.

In particular, the roller shaft support portion 46A is formed with a first auxiliary roller 50A and a second auxiliary roller 52A, and the roller shaft support portion 46B is formed with a first auxiliary roller 50B and a second auxiliary roller 52B. As a result, the first auxiliary roller 50A and the second auxiliary roller 52A revolve around the arm 40 together with the roller 42A, and the first auxiliary roller 50B and the second auxiliary roller 52B revolve around the arm 40 together with the roller 42B. In the enlarged oblique view 104, the first auxiliary roller 50B is shown with a dotted line to indicate that it is located behind the roller 42B in the drawing.

<Pallet lifting device: Support part: Auxiliary roller guide>
The auxiliary roller guide guides the auxiliary roller 48 to alternately change the position of the roller 42 between the first position and the second position as the arm 40 rotates around the shaft 34. The specific configuration of the auxiliary roller guide will be described in further detail with reference to FIG. 4 . FIG. 4 shows a schematic side view 402 and a schematic plan view 404 of a support unit 32, illustrating an extracted portion of the support unit 32. In particular, the schematic side view 402 and the schematic plan view 404 illustrate an extracted portion of the shaft 34, the arm 40, the roller 42, the roller shaft support unit 46, the auxiliary roller 48, and the auxiliary roller guide 54 of the support unit 32. The schematic side view 402 illustrates a portion of the support unit 32 as viewed from the arm 40 side in the extension direction of the shaft 34.

The auxiliary roller guide 54 includes a first guide portion 56, a second guide portion 58, a third guide portion 60, a fourth guide portion 62, a first guide support portion 64, and a second guide support portion 66.

The first guide portion 56, second guide portion 58, third guide portion 60, and fourth guide portion 62 are plate-shaped members whose surfaces rub against the outer circumferential surface of the auxiliary roller 48 as the arm 40 rotates around the shaft 34, as described below. In particular, when viewed from the arm 40 side in the extension direction of the shaft 34, the first guide portion 56, second guide portion 58, third guide portion 60, and fourth guide portion 62 are positioned so as to overlap with the path trajectory traversed by the outer circumferential surface of the auxiliary roller 48 when the arm 40 rotates around the shaft 34. For example, the first guide portion 56, second guide portion 58, third guide portion 60, and fourth guide portion 62 have their longitudinal direction in the circumferential direction centered on the shaft 34.

The first guide portion 56 and the second guide portion 58 are fixed to the first guide support portion 64, and the third guide portion 60 and the fourth guide portion 62 are fixed to the second guide support portion 66. The first guide support portion 64 and the second guide support portion 66 are fixed in position relative to the ground. Therefore, the positions of the first guide portion 56, the second guide portion 58, the third guide portion 60, and the fourth guide portion 62 are fixed regardless of rotation of the arm 40 around the shaft 34.

The first guide portion 56 has a first protrusion 68 at its upper longitudinal end that protrudes in the direction from the shaft 34 toward the arm 40. The second guide portion 58 has a second protrusion 70 at its lower longitudinal end that protrudes in the direction from the arm 40 toward the shaft 34.

<Pallet lifting device: support part: guiding roller from first position to second position>
The change of the roller 42 between the first position and the second position via the guidance of the auxiliary roller 48 by the auxiliary roller guide 54 will be described with reference to Figures 5 and 6. Figure 5 is a schematic diagram showing the state in which the roller 42A changes from the first position to the second position, and Figure 6 is a schematic diagram showing the state in which the roller 42A changes from the second position to the first position. Both the schematic diagrams shown in Figures 5 and 6 are schematic diagrams of the roller 42A and the vicinity of the roller 42A viewed in the direction from the roller 42A toward the roller shaft support portion 46A in the longitudinal direction of the roller shaft 44A.

Schematic diagram 502 shows a state in which the extension direction of arm 40 shown in Figure 4 is approximately aligned with the vertical direction, and roller 42A is in the first position. Due to rotation of shaft 34, roller 42A moves leftward as viewed in schematic diagram 502. Here, the first protrusion 68 of first guide portion 56 is positioned on the path of first auxiliary roller 50A, which moves in conjunction with the movement of roller 42A due to rotation of shaft 34.

Schematic diagram 504 shows the state in which the shaft 34 has rotated from the state shown in schematic diagram 502. As shown in schematic diagram 504, as the shaft 34 rotates and the roller 42A moves, the first auxiliary roller 50A comes into contact with the first protrusion 68.

Schematic diagram 506 shows a state in which the shaft 34 has rotated further from the state shown in schematic diagram 504. As the shaft 34 rotates further from the state in which the first auxiliary roller 50A and the first protrusion 68 are in contact, the end of the arm 40 on the roller 42A side continues to move, while the movement of the first auxiliary roller 50A is prevented by the first protrusion 68. As a result, as shown in schematic diagram 506, the first auxiliary roller 50A is pushed by the first protrusion 68, and as a result, the roller shaft support 46A rotates around the arm 40. As a result, the roller shaft 44A and roller 42A rotate around the arm 40 together with the roller shaft support 46A.

Schematic diagram 508 shows the state in which the shaft 34 has rotated further from the state shown in schematic diagram 506. As shown in schematic diagram 508, when the shaft 34 rotates until the first auxiliary roller 50A passes over the first protrusion 68, the outer surface of the first auxiliary roller 50A rubs against the side surface of the first guide portion 56, causing the first auxiliary roller 50A to begin rotating on its own axis.

Furthermore, as shown in schematic diagram 508, when the shaft 34 rotates until the first auxiliary roller 50A passes over the first protrusion 68, the roller shaft support portion 46A rotates around the arm 40 to a position where the longitudinal direction of the roller shaft 44A is perpendicular to the longitudinal direction of the shaft 34. As a result, the posture of the roller 42A changes from the first posture shown in schematic diagram 502 to the second posture shown in schematic diagram 508.

While the roller 42A is in the second position, the outer surface of the second auxiliary roller 52A rubs against the side surface of the second guide portion 58, causing the second auxiliary roller 52A to rotate. While the outer surface of the second auxiliary roller 52A rubs against the second guide portion 58, the position of the roller 42A is maintained in the second position.

<Pallet lifting device: support part: guiding roller from second position to first position>
Schematic diagram 602 shows a state in which the shaft 34 has further rotated from the state shown in schematic diagram 508. As the shaft 34 continues to rotate from the state shown in schematic diagram 508, the second auxiliary roller 52A moves to the end of the second guide portion 58 on the side of the third guide portion 60. Here, the second protrusion 70 of the third guide portion 60 is positioned on the path of the second auxiliary roller 52A.

Schematic diagram 604 shows the state in which the shaft 34 has rotated from the state shown in schematic diagram 602. As shown in schematic diagram 604, as the shaft 34 rotates and the roller 42A moves, the second auxiliary roller 52A moves away from the second guide portion 58 and comes into contact with the second protrusion 70.

Schematic diagram 606 shows a state in which the shaft 34 has rotated further from the state shown in schematic diagram 604. As the shaft 34 rotates further from the state in which the second auxiliary roller 52A and the second protrusion 70 are in contact, the end of the arm 40 on the roller 42A side continues to move, while the movement of the second auxiliary roller 52A is prevented by the second protrusion 70. As a result, as shown in schematic diagram 606, the second auxiliary roller 52A is pushed by the second protrusion 70, and as a result, the roller shaft support 46A rotates around the arm 40. As a result, the roller shaft 44A and roller 42A rotate around the arm 40 together with the roller shaft support 46A.

Schematic diagram 608 shows a state in which the shaft 34 has rotated further from the state shown in schematic diagram 606, and in particular, a state in which the shaft 34 has rotated to a position in which the arm 40 again extends substantially in the vertical direction. As shown in schematic diagram 608, when the shaft 34 has rotated until the second auxiliary roller 52A passes over the second protrusion 70, the outer peripheral surface of the second auxiliary roller 52A rubs against the side surface of the third guide portion 60, causing the second auxiliary roller 52A to begin rotating on its own axis.

Furthermore, as shown in schematic diagram 608, when the shaft 34 rotates until the second auxiliary roller 52A passes over the second protrusion 70, the roller shaft support portion 46A rotates around the arm 40 to a position where the longitudinal direction of the roller shaft 44A is parallel to the longitudinal direction of the shaft 34. As a result, the posture of the roller 42A changes from the second posture shown in schematic diagram 602 to the first posture shown in schematic diagram 608.

<Pallet lifting device: Support part: Additional information on roller posture control>
If the shaft 34 rotates further from the state shown in schematic diagram 608, the second auxiliary roller 52A continues to rub against the side surface of the third guide portion 60, and the first auxiliary roller 50A rubs against the side surface of the fourth guide portion 62. As a result, the roller shaft support portion 46A is sandwiched between the third guide portion 60 and the fourth guide portion 62 via the first auxiliary roller 50A and the second auxiliary roller 52A, and rotation around the arm 40 is fixed. Therefore, if the shaft 34 rotates further from the state shown in schematic diagram 608, the position of the roller 42A is maintained in the first position until the roller 42A reaches the position shown in schematic diagram 502.

When roller 42A is in the state shown in schematic diagram 502, roller 42B is in the state shown in schematic diagram 608. Therefore, while roller 42A changes from the state shown in schematic diagram 502 to the state shown in schematic diagram 608, in other words, while the posture of roller 42A changes from the first posture to the second posture and then from the second posture to the first posture, roller 42B is maintained in the first posture. Furthermore, while roller 42A changes from the state shown in schematic diagram 608 to the state shown in schematic diagram 502, the posture of roller 42B changes from the first posture to the second posture and then from the second posture to the first posture.

As a result, the respective postures of rollers 42A and 42B alternate between the first posture and the second posture as shaft 34 rotates. In particular, in the support section 32 of the pallet lifting device 24 provided in the ascending section 12, as described above, as shaft 34 rotates, the posture of the descending roller 42 changes from the first posture to the second posture and then back to the first posture, while the posture of the ascending roller 42 is maintained in the first posture.

<Pallet delivery by conveyor>
The transfer of the pallet 4 between the conveying section 6 and the return section 8 by the pallet lifting device 24 will be described in detail with reference to Figure 7. Figure 7 is an enlarged side view of the conveying section 6, the return section 8, and a portion of the pallet lifting device 24 when the pallet lifting device 24 provided in the ascending section 12 moves the pallet 4 from the return section 8 to the conveying section 6.

In particular, the side view of each process in Figure 7 is an enlarged view of the adjacent transport unit 6U and return unit 8U and pallet lifting device 24 viewed in the direction DC shown in the enlarged oblique view 102, in other words, from one side to the other of two rails 26 described below. In the cross-sectional view of each process in Figure 7, the pallet 4 being transported is shown with a dotted line, and the components further back than the pallet 4 toward the page are shown through the pallet 4.

For example, as shown in process side view 702 in Figure 7, assume that the return section 8 transports the pallet 4 to the return unit 8U adjacent to the ascending section 12, in other words, the end of the return path 8W. At this point, the pallet lifting device 24 controls the rotation of the shaft 34 so that the longitudinal direction of the arms 40 of each support section 32 is approximately aligned with the up-down direction. In this case, the height of the upper end of roller 42A is approximately aligned with the height of the upper end of roller 28 of transport unit 6U, and the height of the upper end of roller 42B is approximately aligned with the height of the upper end of roller 28 of return unit 8U.

As a result, the return unit 8U can transport the pallet 4 from the return unit 8U onto the rollers 42B by sending out the pallet 4 using the friction drive unit 30. As a result, as shown in process cross-sectional view 704 in Figure 7, the conveying device 2 moves the pallet 4 from the return section 8 toward the pallet lifting device 24.

As shown in process cross-sectional diagram 704, at least one set of friction drive units 30 provided in the pallet lifting device 24 is positioned so that the drive rollers 30R provided therein can laterally clamp the pallet 4 sent from the return unit 8U. Therefore, the friction drive unit 30 may further drive the pallet 4 sent from the return unit 8U so that the entire pallet 4 leaves the return section 8 and moves to the support section 32 of the pallet lifting device 24. Alternatively, the friction drive unit 30 may stop the rotation of the drive rollers 30R and stop the movement of the pallet 4 so that the pallet 4 sent from the return unit 8U comes to rest on the support section 32.

As shown in process side view 706, the conveying device 2 moves the pallet 4 from the rollers 28 of the return unit 8U onto the rollers 42B of the support section 32, thereby completing the transfer of the pallet 4 from the return section 8 to the pallet lifting device 24.

The pallet lifting device 24 then rotates the shafts 34 of each support 32, as shown in process side view 708, to raise the rollers 42B and the pallet 4 on rollers 42B. While rollers 42B are raised, rollers 42A are lowered, as shown in process side view 708.

Here, the posture of the descending roller 42 changes from the first posture to the second posture due to the guidance of the auxiliary roller 48 by the auxiliary roller guide 54 described above. In particular, in the second posture, the roller shaft 44A is oriented perpendicular to the extension direction of the shaft 34, and the roller 42A is positioned above the roller shaft support portion 46A. Therefore, interference between the roller 42A and the pallet 4 is avoided even while the pallet 4 on the roller 42B is rising. In other words, the second posture of the roller 42A is a posture in which the roller 42A retreats from the pallet 4 on the roller 42B.

As shown in process side view 710, the pallet lifting device 24 rotates the shafts 34 of each support section 32 until the extension direction of the shafts 34 is approximately aligned with the vertical direction. In this case, the height of the upper end of roller 42B is approximately aligned with the height of the upper end of roller 28 of transport unit 6U, and the height of the upper end of roller 42A is approximately aligned with the height of the upper end of roller 28 of return unit 8U. As a result, the pallet 4 rises from above roller 42B until it can be transported onto roller 28 of transport unit 6U.

In this embodiment, as shown in the process side view 710, another pallet 4 may be transported to the return unit 8U on the ascending section 12 side before the pallet 4 has been completely raised. The transport of the other pallet 4 in the return unit 8U may be stopped just before the ascending section 12 until the pallet 4 has been completely raised.

After the pallet 4 has been raised, as shown in process cross-sectional view 712 of Figure 7, each friction drive unit 30 clamps the pallet 4 on roller 42B from the side with drive roller 30R, and rotates drive roller 30R to send it onto roller 28 of transport unit 6U. This causes the transport device 2 to move the pallet 4 from the pallet lifting device 24 toward the transport section 6.

Furthermore, simultaneously with the movement of a pallet 4 from the pallet lifting device 24 to the conveying section 6, as shown in process cross-sectional view 712 of Figure 7, each friction drive unit 30 sends another pallet 4 on the rollers 28 of the return unit 8U onto rollers 42A. As a result, the conveying device 2 moves a pallet 4 from the pallet lifting device 24 toward the conveying section 6, while also moving another pallet 4 from the return section 8 toward the pallet lifting device 24. As a result, the conveying device 2 can simultaneously transfer a pallet 4 from the pallet lifting device 24 to the conveying section 6 using the drive roller 30R, and transfer another pallet 4 from the return section 8 to the pallet lifting device 24 using the other drive roller 30R.

Then, by executing the above method with rollers 42A and 42B interchanged, the pallet lifting device 24 lifts the other pallet 4. By repeatedly executing the same method, the conveying device 2 sequentially transfers pallets 4 from the return section 8 to the conveying section 6 via the pallet lifting device 24.

<Operation of the friction drive unit during pallet transfer>
The operation of the friction drive unit 30 provided in the pallet lifting device 24 while the pallet 4 is being transferred from the return section 8 to the conveying section 6 will be described with reference to Figure 8. Figure 8 is a schematic side view of each drive roller 30R and each pallet 4, showing the positional relationship between each drive roller 30R of the friction drive unit 30 provided in the pallet lifting device 24 and each pallet 4. In particular, schematic side view 802 is a schematic side view while the transfer of the pallet 4 from the return section 8 to the pallet lifting device 24 and the transfer of the pallet 4 from the pallet lifting device 24 to the conveying section 6 are being performed simultaneously. Furthermore, schematic side view 804 is a schematic side view while the pallet lifting device 24 is raising the pallet 4 on roller 42B.

As shown in the schematic side view 802, when transferring pallets 4 between the conveying section 6 or return section 8 and the pallet lifting device 24, the friction drive unit 30 of the pallet lifting device 24 causes the drive rollers 30R to clamp each pallet 4 from the side. In other words, the drive rollers 30R provided in the pallet lifting device 24 clamp the pallet 4 from the side while it is being transported. In the above case, in the direction perpendicular to the conveying direction DT of the pallet 4 and the up-and-down direction, the distance from the drive roller 30R on one end to the drive roller 30R on the other end is approximately the same as the distance from one end to the other end of the pallet 4.

On the other hand, as shown in the schematic side view 802, when the pallet 4 is raised by the pallet lifting device 24, the friction drive unit 30 of the pallet lifting device 24 retracts the drive roller 30R from the pallet 4. In other words, the drive roller 30R provided in the pallet lifting device 24 is separated from the pallet 4 while the pallet 4 is being raised or lowered, in other words, while the arm 40 rotates around the shaft 34.

In particular, the friction drive unit 30 moves the drive roller 30R away from the pallet 4 in a direction perpendicular to the conveying direction DT and the up-down direction of the pallet 4. In the above case, the distance from the drive roller 30R on one end to the drive roller 30R on the other end in the direction perpendicular to the conveying direction DT and the up-down direction of the pallet 4 is longer than the distance from one end to the other end of the pallet 4.

As a result, the friction drive unit 30 provided in the pallet lifting device 24 can transfer the pallet 4 between the conveying section 6 or return section 8 and the pallet lifting device 24 while reducing interference between the pallet 4 and the drive roller 30R.

<Linkage of shaft rotation>
In this embodiment, the case where the shafts 34 of the support parts 32 all rotate counterclockwise when viewed from the rollers 42 to the shafts 34 has been described, but this is not limiting. For example, the shafts 34 of the support parts 32 may rotate clockwise when viewed from the rollers 42 to the shafts 34.

Among the multiple support parts 32 included in one pallet lifting device 24, the height of the upper rollers 42 and the height of the lower rollers 42 may be approximately the same, regardless of the rotation of the shafts 34 of each support part 32. This reduces the tilt of the pallet 4 supported by the multiple support parts 32 of the pallet lifting device 24. In particular, the rotation of the shafts 34 of the multiple support parts 32 included in one pallet lifting device 24 may be linked, in other words, the rotation of the arms 40 may be linked.

An example of a method for interlocking the rotation of the shafts 34 of multiple support parts 32 will be described with reference to Figure 9. Figure 9 is a schematic perspective view showing two support parts 32 of the support parts 32 of the pallet lifting device 24 that are aligned in the conveying direction DT of the pallet 4.

The pallet lifting device 24 may further include a belt 72 stretched over the shafts 34 of two support members 32 aligned in the conveying direction DT of the pallet 4. The belt 72 may also be stretched over the shafts 34 of the other two support members 32 that face the two support members 32 shown in FIG. 9 in a direction perpendicular to the conveying direction DT of the pallet 4 and the vertical direction.

The belt 72 couples the rotation of the arms 40 between the two support sections 32 by transmitting the rotation of the shaft 34. This allows the pallet lifting device 24 to rotate the arms 40 of both support sections 32 simply by driving the rotation of the shaft 34 of one of the two support sections 32.

<Additional Notes>
As described above, in all of the support parts 32 of the pallet lifting devices 24 provided in the ascending section 12, the position of the rollers 42 that descend as the shafts 34 rotate changes from the first position to the second position and then returns to the first position again. Also, as described above, in all of the support parts 32 of the pallet lifting devices 24 provided in the ascending section 12, the position of the rollers 42 that ascend as the shafts 34 rotate is maintained in the first position.

In contrast, in each of the support parts 32 of the pallet lifting device 24 provided in the descending unit 10, the position of the roller 42 that rises as the shaft 34 rotates changes from the first position to the second position and then back to the first position. Furthermore, in each of the support parts 32 of the pallet lifting device 24 provided in the descending unit 10, the position of the roller 42 that falls as the shaft 34 rotates is maintained in the first position. This support part 32 may be achieved by appropriately changing the position of each guide part of the auxiliary roller guide 54.

For this reason, the transfer of the pallet 4 from the conveying section 6 to the return section 8 by the pallet lifting device 24 provided in the lowering section 10 is achieved in the same manner as described above. For example, the conveying device 2 moves the pallet 4 from the conveying section 6 to the pallet lifting device 24, lowers the pallet 4 by the pallet lifting device 24, and moves the pallet 4 from the pallet lifting device 24 to the return section 8, thereby transferring the pallet 4 from the conveying section 6 to the return section 8.

As described above, the conveying device 2 circulates the pallets 4 by transferring them between the conveying section 6, the descending section 10, the returning section 8, and the ascending section 12 in that order. The conveying device 2 circulates multiple pallets 4 while sequentially conveying multiple vehicle bodies X by placing a vehicle body X on each of the multiple pallets 4 located in the conveying section 6.

In this embodiment, the shaft 34 and arm 40 of the support unit 32 of the pallet lifting device 24 both rotate in one direction, but this is not limited to this, and the shaft drive unit 38 may be capable of reversing the direction of rotation of the shaft 34. For example, the support unit 32 may raise and lower the pallet 4 by repeatedly rotating the arm 40 halfway in one direction and then halfway in the opposite direction from a state in which the arm 40 extends vertically. In this case, the rotation of the roller shaft support unit 46 around the arm 40 may be achieved by another drive unit such as a motor, and the support unit 32 may appropriately change the position of each roller 42 between the first position and the second position.

[Embodiment 2]
<Flexible Roller>
Other embodiments of the present disclosure will be described below. For ease of explanation, in the following embodiments, components having the same functions as those described in the previous embodiment will be denoted by the same reference numerals, and their descriptions will not be repeated.

The conveying device 2 according to this embodiment has the same configuration as the conveying device 2 according to the previous embodiment, except that the pallet lifting device 24 has a support portion 74 instead of the support portion 32. The support portion 74 according to this embodiment will be described with reference to Figure 10. Figure 10 is an enlarged perspective view of the support portion 74.

Compared to the support part 32 of the previous embodiment, the support part 74 of this embodiment includes a roller 76, a roller shaft 78, and a roller shaft support part 80 instead of the roller 42, roller shaft 44, and roller shaft support part 46, respectively.

The rollers 76 are formed on both ends of the arm 40 and revolve around the shaft 34 as the shaft 34 rotates. The roller shafts 78 are formed on the roller shaft support portions 80, and the rollers 76 rotate around the roller shafts 78. In this embodiment, the roller shaft support portions 80 are fixed to the arm 40. Therefore, unless an external force, as described below, is applied to the rollers 76 and roller shafts 78, the roller shafts 78 always extend in a direction substantially parallel to the extension direction of the shaft 34.

The rollers 76 and roller shafts 78 according to this embodiment are both flexible and elastic. In particular, when a force perpendicular to the extension direction of the shaft 34 is applied to the rollers 76 and roller shafts 78, they bend from a state in which they are extended substantially parallel to the extension direction of the shaft 34, around the roller shaft support portion 80. On the other hand, when the force is released, the rollers 76 and roller shafts 78 return to a state in which they are extended substantially parallel to the extension direction of the shaft 34. Note that the rollers 76 and roller shafts 78 do not have to be restored to a state in which they are extended completely parallel to the extension direction of the shaft 34; they only need to be restored to a degree that does not interfere with the rotation of the rollers 76 around the roller shafts 78. The rollers 76 and roller shafts 78 may have a longer axial length than the rollers 42 and roller shafts 44.

The support portion 74 has, for example, two rollers 76: roller 76A that rotates around roller axle 78A and roller 76B that rotates around roller axle 78B. In particular, Figure 10 shows the support portion 74 in a state in which roller 76A is located at the upper end of the arm 40 and roller 76B is located at the lower end of the arm 40. The support portion 74 also has two roller axle support portions 80: roller axle support portion 80A where roller axle 78A is formed, and roller axle support portion 80B where roller axle 78B is formed.

Apart from the above, the support section 74 according to this embodiment has the same configuration as the support section 32 according to the previous embodiment. Therefore, in the pallet lifting device 24 according to this embodiment, each roller 76 of the support section 74 can also take the first position for supporting the pallet 4.

The raising and lowering of a pallet 4 by the pallet lifting device 24 according to this embodiment will be described with reference to Figure 11. Figure 11 is an enlarged side view of one of the support portions 74 and a portion of the pallet 4 when the pallet 4 is being supported and raised and lowered by the pallet lifting device 24. In particular, Figure 11 shows one of the support portions 74 and a portion of the pallet 4 as viewed in the return direction DR.

In this embodiment, the transport of the pallet 4 from the conveying section 6 or the return section 8 to the pallet lifting device 24 is achieved in the same manner as in the previous embodiment. In particular, the enlarged side view 1102 in Figure 11 shows the state in which the pallet 4 has been transported from above roller 28 of the return section 8 to above roller 76B of the support section 74, with the extension direction of the arm 40 in the vertical direction and roller 76B below roller 76A.

In this embodiment, the rollers 76 and roller shafts 78 may be flexible as described above, but may also have sufficient rigidity to prevent them from bending under a force equivalent to the weight of the pallet 4. For example, the rollers 76 and roller shafts 78 may have sufficient rigidity to support the pallet 4 when it is loaded on the rollers 76.

When a pallet 4 is loaded on roller 76B, which is located below roller 76A, and shaft 34 and arm 40 rotate, the pallet 4 and roller 76B rise, while roller 76A descends. As shaft 34 and arm 40 continue to rotate, roller 76A comes into contact with the pallet 4 on roller 76B.

As a result, roller 76A is pushed up by pallet 4 on roller 76B on the side opposite arm 40. As a result, roller 76A bends upward together with roller shaft 78A, as shown in enlarged side view 1104.

Continuing rotation of the shaft 34 and arm 40 releases roller 76A from contact with the pallet 4 on roller 76B. As a result, roller 76A and roller shaft 78A are restored to the first position, extending in approximately the same direction as the extension direction of shaft 34, as shown in enlarged side view 1106.

When raising and lowering the pallet 4 in this embodiment, the shaft 34 and arm 40 rotate until the extension direction of the arm 40 is vertical and roller 76B is positioned above roller 76A. This completes the lifting of the pallet 4 on roller 76B, as shown in enlarged side view 1106. In this embodiment, the transport of the pallet 4 from the pallet lifting device 24 to the conveying section 6 or return section 8 is achieved in the same manner as in the previous embodiment. In particular, as shown in enlarged side view 1106 in Figure 11, the pallet 4 on roller 76B that has completed the lifting is transported from roller 76B of the support section 74 to roller 28 of the conveying section 6.

As shown in enlarged side view 1106, when the lifting of pallet 4 on roller 76B is complete, roller 76A has returned to the first position. Therefore, the conveying device 2 according to this embodiment can at that point convey another pallet 4 on roller 28 of the return section 8 to roller 76A of the support section 74. In other words, the conveying device 2 according to this embodiment can simultaneously convey a pallet 4 from the pallet lifting device 24 to the conveying section 6 and another pallet 4 from the return section 8 to the pallet lifting device 24.

In this embodiment, the transfer of pallets 4 from the conveying section 6 to the return section 8 by the pallet lifting device 24 provided in the descending section 10 is achieved in a manner similar to that described above. As described above, the conveying device 2 according to this embodiment circulates pallets 4 by transferring pallets 4 in the following order: conveying section 6, descending section 10, return section 8, and ascending section 12.

[Embodiment 3]
<Rollers that go around the pallet>
A further embodiment of the present disclosure will now be described with reference to Figure 12. Figure 12 shows an enlarged perspective view 1202 of a portion of the transport device 2 and an enlarged perspective view 1204 of a support portion 82, which is part of the pallet lifting device 24 and will be described later.

Compared to the conveying device 2 of embodiment 1, the conveying device 2 of this embodiment has a pallet lifting device 24 equipped with a support portion 82 instead of the support portion 32, as shown in enlarged oblique view 1202. Furthermore, the pallet lifting device 24 of this embodiment has the support portion 82 closer to the end of the conveying direction DT than the friction drive unit 30. Except for the above, the conveying device 2 of this embodiment has the same configuration as the conveying device 2 of embodiment 1.

The support part 82 according to this embodiment has the same configuration as the support part 32 according to the first embodiment, except that it includes the roller shaft support part 80 according to the previous embodiment instead of the roller shaft support part 46, as shown in the enlarged oblique view 1204. In other words, the support part 82 according to this embodiment has the same configuration as the support part 32 according to the first embodiment, except that the roller 42 is always in the first position regardless of the rotation of the arm 40 around the shaft 34.

Note that the support portion 82 has, for example, two rollers 42: roller 42A that rotates around roller shaft 44A and roller 42B that rotates around roller shaft 44B. In particular, the enlarged oblique view 1204 shows the support portion 82 in a state in which roller 42A is located at the upper end of the arm 40 and roller 42B is located at the lower end of the arm 40. Furthermore, the support portion 82 has, as two roller shaft support portions 80, roller shaft support portion 80A where roller shaft 44A is formed and roller shaft support portion 80B where roller shaft 44B is formed.

The raising and lowering of the pallet 4 by the pallet lifting device 24 according to this embodiment will be described with reference to Figure 13. Figure 13 is an enlarged side view of a portion of the pallet lifting device 24 and the pallet 4 when the pallet 4 is being supported and raised and lowered by the pallet lifting device 24.

In particular, Figure 13 shows two support members 74 of the pallet lifting device 24 as viewed in a direction perpendicular to the conveying direction DT and the up-down direction. In Figure 13, the pallet 4 is shown with a dotted line, and the components further back than the pallet 4 are shown transparently. Also, to clearly illustrate the entire pallet 4, the scale of the pallet 4 in the conveying direction DT in Figure 13 has been reduced so that the entire pallet 4 fits within each view of Figure 13.

In this embodiment, the transport of the pallet 4 from the conveying section 6 or return section 8 to the pallet lifting device 24 is achieved using the same method as in the previous embodiments. In particular, the enlarged side view 1302 in Figure 13 shows the state in which the pallet 4 has been transported from above roller 28 of the return section 8 to above roller 42B of the support section 82, with the extension direction of the arm 40 in the vertical direction and roller 42B below roller 42A.

As described above, the pallet lifting device 24 according to this embodiment has the support parts 82 located closer to the end in the conveying direction DT than the friction drive unit 30. Therefore, each support part 82 of the pallet lifting device 24 according to this embodiment supports the pallet 4 by supporting the end of the pallet 4 in the conveying direction DT with the rollers 42B.

When a pallet 4 is loaded on roller 42B, which is located below roller 42A, and the shaft 34 and arm 40 rotate, the pallet 4 and roller 42B rise, while roller 42A descends. In this embodiment, as shown in enlarged side view 1304, the arm 40 of each support unit 82 rotates so that the roller 42B supporting the pallet 4 moves toward the center of the pallet 4 in the conveying direction DT. For example, as shown in enlarged side view 1304, the arm 40 of the support unit 82 on the left side of the page rotates counterclockwise, while the arm 40 of the support unit 82 on the right side of the page rotates clockwise.

As a result, in this embodiment, as shown in the enlarged side view 1304, the rollers 42A of each support portion 82 descend while passing further around the periphery of the pallet 4 than the end of the pallet 4 in the conveying direction DT. As a result, the rollers 42A of each support portion 82 descend while maintaining the first posture by moving around the pallet 4.

When raising and lowering the pallet 4 in this embodiment, the shaft 34 and arm 40 rotate until the extension direction of the arm 40 is vertical and roller 42B is positioned above roller 42A. This completes the lifting of the pallet 4 on roller 42B, as shown in enlarged side view 1306. In this embodiment, the transport of the pallet 4 from the pallet lifting device 24 to the conveying section 6 or return section 8 is achieved in the same manner as in the previously described embodiments. In particular, as shown in enlarged side view 1306 in Figure 13, the pallet 4 on roller 42B that has completed the lifting is transported from roller 42B of the support section 82 to roller 28 of the conveying section 6.

As shown in each diagram in Figure 13, the roller 42A remains in the first position regardless of the rotation of the arm 40. Therefore, the conveying device 2 according to this embodiment can convey another pallet 4 on the roller 28 of the return section 8 onto the roller 42A once the lifting of the pallet 4 on the roller 42B of the support section 82 is complete. In other words, the conveying device 2 according to this embodiment can simultaneously convey a pallet 4 from the pallet lifting device 24 to the conveying section 6 and another pallet 4 from the return section 8 to the pallet lifting device 24.

In this embodiment, the transfer of pallets 4 from the conveying section 6 to the return section 8 by the pallet lifting device 24 provided in the descending section 10 is achieved in a manner similar to that described above. As described above, the conveying device 2 according to this embodiment circulates pallets 4 by transferring pallets 4 in the following order: conveying section 6, descending section 10, return section 8, and ascending section 12.

<Summary>
(1) A pallet lifting device according to aspect 1 of the present disclosure is a pallet lifting device that raises or lowers a pallet fed at a first height to a second height before feeding it out, and includes a plurality of support parts for supporting and raising or lowering the pallet, each of which has an arm extending in a direction perpendicular to a first axis, which is a horizontal axis, and which rotates around the first axis located in the center of the arm's longitudinal direction, and a pair of rollers provided at both ends of the arm, and each of the rollers is configured so that the roller axis is perpendicular to a second axis along the longitudinal direction of the arm and parallel to the first axis, such that the roller can assume a first position for supporting the pallet.

With the above configuration, the pallet lifting mechanism can remove a pallet from one roller and load another pallet onto the other roller by placing both of a pair of rollers in the first position. Therefore, the pallet lifting device can remove a pallet that has been lifted and load another pallet without requiring time to load another pallet after removing the lifted pallet. After removing the pallet and loading another pallet, it can then move on to lifting and lowering the other pallet. Therefore, the pallet lifting device can lift and lower multiple pallets in a shorter time.

(2) In the pallet lifting device according to aspect 2 of the present disclosure, the roller shaft of each of the rollers in aspect 1 above is rotatable around the second shaft, and the roller shaft rotates around the second shaft from the first position, allowing the roller to assume a second position in which it retracts from the pallet.

With the above configuration, even when the pallet lifting mechanism rotates the arm to raise or lower a pallet while the pallet is loaded on one roller, interference between the other roller and the pallet can be reduced by switching the position of the other roller to the second position. This allows the pallet lifting mechanism to efficiently raise and lower the pallet regardless of the position of the support part relative to the pallet being raised or lowered.

(3) In a pallet lifting device according to aspect 3 of the present disclosure, as in aspect 2 above, each of the support parts has an auxiliary roller that revolves around the second axis in conjunction with the roller axis of each of the rollers, and an auxiliary roller guide that guides the auxiliary roller and alternately changes the position of the roller between the first position and the second position as the arm rotates.

With the above configuration, the pallet lifting mechanism can switch the roller position between the first position and the second position simply by rotating the arm. Therefore, the pallet lifting device does not need to have a separate drive unit for changing the roller position, and the support unit can be realized with a simpler configuration.

(4) In the pallet lifting device according to aspect 4 of the present disclosure, in aspect 2 or 3 above, the roller in the second position is positioned higher on the opposite side than on the arm side.

With the above configuration, the pallet lifting mechanism can reduce the likelihood of the roller being positioned lower than the lower end of the arm when the roller is in the second position. Therefore, the pallet lifting device can reduce interference between the ground and the roller even when the support part is positioned lower from the ground. By positioning the support part lower from the ground, the pallet lifting device can reduce the overall height of the device; in other words, the height at which the pallet is loaded and unloaded is reduced.

Reducing the height of a pallet lifting device means that the height at which pallets are transported can be lowered in a transport device equipped with the pallet lifting device. When a transport device transports a pallet loaded with an object such as a vehicle body, and a worker transfers onto the transported pallet to work on the object, lowering the height at which the pallet is transported reduces the burden on the worker getting on and off the pallet.

(5) In the pallet lifting device according to aspect 5 of the present disclosure, as in aspect 1 above, while the arm rotates around the first axis with the pallet loaded on one of the pair of rollers formed on the arm, the other of the pair of rollers bends as it comes into contact with the pallet and returns to its original position as it is released from contact with the pallet.

With the above configuration, even when the pallet comes into contact with the rollers, the pallet lifting mechanism deforms the rollers to avoid the pallet, and then returns to its original shape when the contact with the pallet is released, allowing another pallet to be loaded onto the rollers. Therefore, the pallet lifting device eliminates the need for a mechanism to rotate the rollers around the arms, and allows pallets to be raised and lowered efficiently regardless of the position of the support part relative to the pallet being raised or lowered.

(6) In a pallet lifting device according to aspect 6 of the present disclosure, in aspect 1 above, each of the rollers is in the first position regardless of rotation of the arm about the first axis, and while the arm rotates about the first axis with the pallet loaded on one of the pair of rollers formed on the arm, the other of the pair of rollers moves around the pallet.

With the above configuration, the pallet lifting mechanism can raise and lower the pallet while the rollers avoid the pallet, while keeping the rollers in the first position. Therefore, the pallet lifting device eliminates the need for a mechanism to rotate the rollers around the arms, and enables efficient lifting and lowering of the pallet while minimizing a decrease in roller rigidity.

(7) The pallet lifting device according to aspect 7 of the present disclosure is any one of aspects 1 to 6 above, further comprising a first drive roller that transports the pallet at the first height and a second drive roller that transports the pallet at the second height.

With the above configuration, the pallet lifting mechanism allows the drive rollers to transport pallets being loaded or unloaded, and also allows the loaded pallet to stop at a specified position.

(8) The pallet lifting device according to aspect 8 of the present disclosure is the same as in aspect 7 above, except that it includes a first drive roller that transports the pallet at the first height and a second drive roller that transports the pallet at the second height.

With the above configuration, the pallet lifting mechanism can more efficiently remove a pallet and simultaneously load another pallet, making it possible to lift and lower multiple pallets in a shorter time.

(9) In a pallet lifting device according to aspect 9 of the present disclosure, in aspect 7 or 8 above, the first drive roller and the second drive roller each hold the pallet from the sides while the pallet is being transported, but move away from the pallet while the arm rotates around the first axis.

With the above configuration, the pallet lifting mechanism can reduce interference between the pallet and the drive roller.

(10) In the pallet lifting device according to aspect 10 of the present disclosure, in any of aspects 7 to 9 above, at least one of the rollers is a driven roller.

With the above configuration, the pallet lifting mechanism enables pallet transport while reducing the number of drive units required to rotate the rollers.

(11) In the pallet lifting device according to aspect 11 of the present disclosure, in any of aspects 1 to 10 above, each of the arms rotates in only one direction around the first axis.

With the above configuration, the pallet lifting mechanism does not require mechanisms for switching the rotation direction of the arm, allowing for a simpler support structure.

(12) In a pallet lifting device according to aspect 12 of the present disclosure, in any of aspects 1 to 11 above, each support part has a shaft formed in the longitudinal center of the arm and extending along the first axis, and is equipped with a belt that is stretched between the shafts of the multiple support parts and links the rotation of the multiple arms.

With the above configuration, the pallet lifting mechanism reduces the number of drive units that rotate the arms while enabling the arms to rotate in unison between multiple support units.

(13) A conveying device according to aspect 13 of the present disclosure is a conveying device comprising: a conveying unit that conveys a pallet in the conveying direction along a conveying path located at the first height; a return unit that conveys the pallet in the opposite direction to the conveying direction along a return path located below the conveying path and at the second height; a descending unit that transfers the pallet from the conveying path to the return path; and an ascending unit that transfers the pallet from the return path to the conveying path, wherein at least one of the descending unit and the ascending unit is equipped with a pallet lifting device according to any one of aspects 1 to 12 above.

With the above configuration, the conveying device can circulate multiple pallets in a shorter time, reducing the time required to transport multiple objects.

(14) A conveying device according to aspect 14 of the present disclosure is the same as that of aspect 13 above, except that both the lowering section and the ascending section are equipped with the pallet lifting device.

With the above configuration, the conveying device can circulate multiple pallets in an even shorter time, further reducing the time required to transport multiple objects.

This disclosure 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 this disclosure.

2 Conveying device 4 Pallet 6 Conveying section 8 Returning section 10 Descending section 12 Ascending section 24 Pallet lifting device 30R Driving roller 32 Supporting section 34 Shaft 40 Arm 42 Roller 44 Roller shaft 48 Auxiliary roller 54 Auxiliary roller guide 72 Belt

Claims (14)

A pallet lifting device that raises or lowers a pallet fed at a first height to a second height and then feeds the pallet out,
a plurality of support parts for supporting and elevating the pallet;
Each of the support portions is
an arm extending in a direction perpendicular to a first axis, which is a horizontal axis, and rotating around the first axis located at the center of the arm in its longitudinal direction;
a pair of rollers provided at both ends of the arm;
Each of the rollers is
The roller axis is perpendicular to the second axis along the longitudinal direction of the arm,
A pallet lifting device, wherein the rollers are configured to be able to take a first position for supporting the pallet, with the roller axes being parallel to the first axis. Each of the rollers is
The roller shaft is rotatable around the second shaft,
2. The pallet lifting device according to claim 1, wherein the device is configured to be capable of assuming a second position in which the roller shaft rotates around the second shaft from the first position and the roller retreats from the pallet. Each of the support portions is
3. A pallet lifting device as described in claim 2, further comprising: an auxiliary roller that revolves around the second axis in conjunction with the roller axis of each of the rollers; and an auxiliary roller guide that guides the auxiliary roller and alternately changes the position of the roller between the first position and the second position as the arm rotates. A pallet lifting device as described in claim 2, wherein the roller in the second position is positioned higher on the opposite side than on the arm side. A pallet lifting device as described in claim 1, wherein, while the arm rotates around the first axis with the pallet loaded on one of the pair of rollers formed on the arm, the other of the pair of rollers bends upon contact with the pallet and returns to its original position upon release from contact with the pallet. each of the rollers is in the first position regardless of rotation of the arm about the first axis;
A pallet lifting device as described in claim 1, wherein while the arm rotates around the first axis with the pallet loaded on one of the pair of rollers formed on the arm, the other of the pair of rollers moves around the pallet. A pallet lifting device according to any one of claims 1 to 6, comprising a first drive roller that transports the pallet at the first height and a second drive roller that transports the pallet at the second height. A pallet lifting device as described in claim 7, wherein the first drive roller can transport the pallet and the second drive roller can transport another pallet simultaneously. A pallet lifting device as described in claim 7, wherein the first drive roller and the second drive roller each clamp the pallet from the sides while the pallet is being transported, but move away from the pallet while the arm rotates around the first axis. A pallet lifting device as described in claim 7, wherein at least one of the rollers is a driven roller. A pallet lifting device as described in any one of claims 1 to 6, wherein each of the arms rotates in only one direction around the first axis. Each of the support portions has a shaft formed at the center of the arm in the longitudinal direction and extending along the first axis,
7. A pallet lifting device according to claim 1, further comprising a belt that is stretched between the shafts of the plurality of support parts and links the rotation of the plurality of arms. a conveying unit that conveys a pallet in a conveying direction along a conveying path located at the first height;
a return unit that transports the pallet in a direction opposite to the transport direction along a return path located below the transport path and at the second height;
a descending section that transfers the pallet from the conveying path to the return path;
a lifting section that transfers the pallet from the return path to the conveying path,
A conveying device, wherein at least one of the descending section and the ascending section is provided with the pallet lifting device according to any one of claims 1 to 6. The conveying device described in claim 13, wherein both the descending section and the ascending section are equipped with the pallet lifting device.