Article lift device and article transport vehicle provided with article lift device

A fixing device that fixes a lower end portion of a suspension belt to a holding portion is provided with a shaft-like portion with an axial direction aligned with a horizontal direction; a fixing portion where the lower end portion of the suspension belt is fixed is provided on an outer circumferential surface of the shaft-like portion; a region of the outer circumferential surface on one side of a virtual vertical surface that runs through an axial center of the shaft-like portion is defined as a first region and a region of the outer circumferential surface on the other side of the virtual vertical surface is defined as a second region; the fixing portion is provided in the first region; and the suspension belt extending from the fixing portion is disposed running through a lowest portion of the outer circumferential surface and running along the second region and upward.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2020-172122 filed Oct. 12, 2020, the disclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an article lift device that raises and lowers an article-holding holding portion with the holding portion being in a suspended state, and an article transport vehicle provided with such an article lift device.

2. Description of the Related Art

An example of such an article lift device is described in JP 2019-185499 (Patent Document 1). The reference signs in brackets used in the description of the related art are those of Patent Document 1.

As illustrated in FIG. 2 of Patent Document 1, the article lift device described in Patent Document 1 is provided with a ceiling transport vehicle (V) that travels on a track (2) provided in a ceiling region. In the article lift device, a holding portion (18a) that holds an article (W) is suspended by a suspension member (18b) constituted by a wire, a belt, or the like. The suspension member (18b) can be wound up or fed out to raise and lower the holding portion (18a). The suspension member (18b) is configured to be wound up or fed out by a lift driving portion (20) located in an upper portion, and the holding portion (18a) is fixed to a lower portion.

SUMMARY OF THE INVENTION

A belt (hereinafter referred to as a suspension belt) is often used as the suspension member (18b). However, such suspension belts may experience deflection or twisting when the stress acting in the extension direction of the suspension belt is non-uniform in the width direction. In particular, if a lower end portion of the suspension belt is not appropriately fixed to the holding portion (18a), a non-uniform stress is likely to act on the suspension belt. On this matter, Patent Document 1 gives no specifics about the structure for fixing together the suspension member (18b) and the holding portion (18a).

In light of the foregoing, there is a need for technology that enables a suspension belt to be appropriately fixed to a holding portion.

An article lift device according to the present disclosure includes:

a holding portion that holds an article;

a lift device that raises and lowers the holding portion with the holding portion being suspended by a suspension belt; and

a fixing device that fixes a lower end portion of the suspension belt to the holding portion, wherein

the fixing device includes a shaft-like portion with an axial direction aligned with a horizontal direction and a connection portion that connects the shaft-like portion and the holding portion together;

the connection portion connects the shaft-like portion and the holding portion together in a manner so that an outer circumferential surface of the shaft-like portion is separated from the holding portion;

a fixing portion where the lower end portion of the suspension belt is fixed is provided on the outer circumferential surface;

in an axial direction view along the axial direction, a region of the outer circumferential surface on one side of a virtual vertical surface running through an axial center of the shaft-like portion is defined as a first region and a region of the outer circumferential surface on the other side of the virtual vertical surface is defined as a second region;

the fixing portion is provided in the first region; and

the suspension belt extending from the fixing portion is disposed running through a lowest portion of the outer circumferential surface and running along the second region and upward.

According to the present configuration, the suspension belt is fixed in the first region of the outer circumferential surface of the shaft-like portion. Also, the suspension belt extending from the fixing portion is disposed running through a lowest portion of the outer circumferential surface and running along the second region and upward. Thus, the tensile load acting on the suspension belt as a result of supporting the weight of the holding portion can press the suspension belt against the lower portion of the outer circumferential surface of the shaft-like portion. Accordingly, the suspension belt can be brought into contact with the outer circumferential surface in the second region from the lowest portion of the outer circumferential surface of the shaft-like portion. Also, the position where the suspension belt extending upward separates from the outer circumferential surface in the second region is easily set at a height at or near the axial center of the shaft-like portion. Thus, according to the present configuration, the suspension belt can be brought into contact with the outer circumferential surface of the shaft-like portion in a relatively large area. Because of this, the contact pressure between the suspension belt and the outer circumferential surface of the shaft-like portion can be made substantially uniform in the width direction of the suspension belt. Thus, according to the present configuration, it is difficult for the stress acting in the extension direction of the suspension belt to be non-uniform in the width direction of the suspension belt, which makes it less likely for the suspension belt to experience deflection or twisting.

Other advantages of the technology according to the present disclosure will be made clear from the description of the exemplary and non-limiting embodiments described below with reference to the drawings.

DETAILED DESCRIPTION OF PREFFERED EMBODIMENTS

An article lift device and an article transport vehicle provided with an article lift device according to an embodiment will now be described using an example of the article transport vehicle being used in an article transport facility.

As illustrated inFIGS.1and2, an article transport facility100is provided with an article transport vehicle V for transporting an article8, a rail Ra constituting a travel path R for the article transport vehicle V, and a transfer section9where the article8is transferred between article transport vehicles V.

A support base92that supports the article8is provided at the transfer section9. In the present embodiment, the support base92is disposed adjacent to a processing device91that processes the article8. Also, the article transport vehicle V transports the article8before it is processed by the processing device91from a non-illustrated transportation starting point to the support base92and transports the article8after it is processed by the processing device91from the support base92to a non-illustrated transportation destination. In the present embodiment, the article8is a container for storing a processing object to be processed by the processing device91. The phrase “process the article8” mentioned above means processing of a processing object stored in the article8. For example, the article8may be a front opening unified pod (FOUP), i.e., a wafer storage container for storing wafers, or may be a reticle storage container (i.e., reticle pod) for storing reticles. In a case where the article8is a FOUP, the processing object is a wafer. In a case where the article8is a reticle pod, the processing object is a reticle. Note that the transfer section9is not limited to this configuration, and, for example, the transfer section9may be a support base disposed adjacent to a stocker for housing the article8, a buffer for temporarily holding the article8, or the like.

The article transport vehicle V is provided with an article lift device4that raises and lowers the article8and a travel portion1that is connected to the article lift device4and that travels along a specific travel path R. The article lift device4is provided with a holding portion41that holds the article8and a lift device42that raises and lowers the holding portion41with the holding portion41being suspended by a suspension belt421. The lift device42is provided with the suspension belt421that suspends the holding portion41and a lift motor M42that drives the suspension belt421and raises and lowers the holding portion41between a raised position and a lowered position. Also, the article transport vehicle V is provided with a housing portion2that houses the holding portion41when the holding portion41is at the raised position and a cover3that covers the housing portion2. Note that, at the lowered position, the holding portion41is disposed at a height corresponding to the support base92of the transfer section9.

The travel portion1is provided with a travel wheel10that rolls on the rail Ra and a travel motor M1that drives the travel wheel10. In the illustrated example, a plurality of the travel wheels10are provided on the article transport vehicle V. The travel motor M1drives at least one of the plurality of travel wheels10and generates a propulsion force to make the article transport vehicle V travel.

The cover3is supported in a suspended state by the travel portion1. In the article transport vehicle V according to the present embodiment, the travel portion1is disposed above the rail Ra and the cover3is disposed below the rail Ra. In the present example, the cover3covers the upper side of the housing portion2and both sides of the housing portion2in the travel direction of the travel portion1.

As described above, the article lift device4is provided with the holding portion41for holding the article8and the lift device42for raising and lowering the holding portion41.

As illustrated inFIGS.2and3, the holding portion41is provided with a pair of gripping claws411and a gripping motor (not illustrated) that makes the pair of gripping claws411come together or separate. Also, the holding portion41is configured to switch between a gripping state in which the pair of gripping claws411grip the article8and a grip release state in which the gripping state is released by the pair of gripping claws411being brought together or separated via the driving the gripping motor. In other words, in the present example, the holding portion41is configured to hold the article8(a flange portion of the FOUP in the illustrated example) by the pair of gripping claws411gripping the article8.

In the present embodiment, the holding portion41is provided with a base portion410where devices are placed and a casing412that covers the devices placed on the base portion410. The pair of gripping claws411are disposed projecting downward through the base portion410. Note that inFIGS.2and3, various devices, such as a structure and gripping motor that makes the pair of gripping claws411come together or separate as described above, are omitted.

As illustrated inFIG.2, the lift device42is provided with a pulley420, the suspension belt421wound around the pulley420, and the lift motor M42that rotates the pulley420and drives the suspension belt421. The suspension belt421is wound around the pulley420at the upper portion and fixed to the holding portion41at the lower portion. The lift device42rotates the pulley420in the forward direction via driving of the lift motor M42to wind up the suspension belt421and raise the holding portion41and the article8held by the holding portion41. Also, the lift device42rotates the pulley420in the reverse direction via driving of the lift motor M42to feed out the suspension belt421and lower the holding portion41and the article8held by the holding portion41. By the lift device42raising and lowering the article8held by the holding portion41, the article8can be transferred between the support bases92(transfer sections9) disposed below the housing portion2.

As illustrated inFIGS.2to4, the article lift device4is provided with a fixing device43for fixing a lower end portion421dof the suspension belt421to the holding portion41. In the present embodiment, the lower end portion421dof the suspension belt421is fixed to the base portion410of the holding portion41by the fixing device43. Note that the lower end portion421dof the suspension belt421indicates the portion of the suspension belt421ranging from the lowest end to a certain distance toward the center in the longitudinal direction. In other words, the lower end portion421dof the suspension belt421is not to be interpreted as one point at the lower end of the suspension belt421. In the present embodiment, the lower end portion421dincludes at least the portion that comes into contact with a shaft-like portion430, described below, of the fixing device43.

As illustrated inFIGS.2and3, in the present example, the article lift device4is provided with a plurality of units that include the pulley420, the suspension belt421, and the fixing device43. In the illustrated example, the article lift device4is provided with three of these units. Each unit has a similar structure, and the positional relationship between the units is set to allow the holding portion41to be maintained in a horizontal orientation.

As illustrated inFIGS.4to7, the fixing device43is provided with the shaft-like portion430with an axial direction L aligned with the horizontal direction and a connection portion431that connects the shaft-like portion430and the holding portion41together. When the holding portion41is in an ideal horizontal orientation, the shaft-like portion430is disposed with the axial direction L parallel with the horizontal direction. However, the axial direction L of the shaft-like portion430being “aligned with the horizontal direction” is not limited to meaning strictly parallel with the horizontal direction and includes in its meaning being roughly parallel with the horizontal direction. In other words, the axial direction L of the shaft-like portion430may be a direction that is inclined with respect to the horizontal direction within a specific tolerance range. Here, “inclined within a specific tolerance range” includes in its meaning being inclined due to a manufacturing error. Also, for example, in a case such as where the holding portion41is inclined with respect to the horizontal direction, the axial direction L of the shaft-like portion430may also be inclined with respect to the horizontal direction, but this inclination is also included within the predetermined tolerance range.

In the present embodiment, a pair of the connection portions431are provided projecting upward from the base portion410of the holding portion41. The two end portions of a shaft S are supported by the pair of connection portions431. Here, the shaft S is supported with its axis aligned with the horizontal direction. In the present example, the portion of the shaft S disposed between the pair of connection portions431corresponds to the shaft-like portion430.

The connection portions431connect the shaft-like portion430and the holding portion41together in a manner so that an outer circumferential surface430F of the shaft-like portion430is separated from the holding portion41. In the present embodiment, the pair of connection portions431support the shaft-like portion430(the shaft S) at a position above and separated from the base portion410. In this manner, the outer circumferential surface430F of the shaft-like portion430is disposed at a position above and separated from the base portion410.

In the present embodiment, the shaft-like portion430is provided with a cover portion430C. The cover portion430C is provided covering the outer circumferential surface of the shaft S at a region in the axial direction L of the shaft S. The cover portion430C is disposed between the shaft S and the suspension belt421in the radial direction. As illustrated inFIG.7, the shape of the cover portion430C is formed to conform to the outer circumferential surface of the shaft S. In the present embodiment, the outer circumferential surface of the cover portion430C corresponds to the outer circumferential surface430F of the shaft-like portion430.

As illustrated inFIG.5, in the present embodiment, the shaft-like portion430is provided with a positioning portion430efor positioning the suspension belt421in the axial direction L. In the present example, by cutting a region in the axial direction L and the circumferential direction of the cylindrical shaft S into a planar shape, as illustrated inFIG.4, a step portion is formed on both sides of the planar region in the axial direction L. This step portion corresponds to the positioning portion430e. Here, the step portion includes a pair of step surfaces facing one another in the axial direction L on either side of the planar region. Also, a region of the extension direction of the suspension belt421is disposed between these pairs of step surfaces. In this manner, the suspension belt421is disposed sandwiched by the pair of step surfaces in the axial direction L. This allows the suspension belt421to be positioned in the axial direction L with respect to the shaft-like portion430.

Here, as illustrated inFIG.7, when viewing the outer circumferential surface430F of the shaft-like portion430in the axial direction L along the axial direction L, the region of the outer circumferential surface430F on one side of an axial center Ax of the shaft-like portion430in the horizontal direction is defined as a first region F1and the other region in the horizontal direction is defined as a second region F2. In other words, in a case where the outer circumferential surface430F is divided along a virtual vertical surface AxF running through the axial center Ax of the shaft-like portion430, one of the divided regions is the first region F1and the other divided region is the second region F2.

A fixing portion430awhere the lower end portion421dof the suspension belt421is fixed is provided on the outer circumferential surface430F. The fixing portion430ais provided in the first region F1. Also, the suspension belt421extending from the fixing portion430ais disposed running through a lowest portion430dof the outer circumferential surface430F and running along the second region F2and upward. In the present embodiment, a guide portion430bfor guiding the suspension belt421to the pulley420(seeFIG.2and the like) side is provided in the second region F2of the outer circumferential surface430F. In other words, in the present embodiment, the fixing portion430ais provided on one side (the first region F1) of the virtual vertical surface AxF of the outer circumferential surface430F and the guide portion430bis provided on the other side (the second region F2). In the present example, the guide portion430bcorresponds to the surface of the outer circumferential surface430F is the second region F2.

As illustrated inFIG.6, in the present embodiment, the fixing portion430ais formed in a planar shape with a dimension (referred to as an axial direction dimension La) in the axial direction L equal to or greater than a belt width421W of the suspension belt421(see alsoFIG.7). Thus, because the fixing portion430aand the suspension belt421are brought into contact flat against one another, the suspension belt421can be easily fixed at the fixing portion430aappropriately. In the illustrated example, the belt width421W and the axial direction dimension La of the fixing portion430aare substantially the same size. Also, in the present example, the planar region forming the fixing portion430ais the same as the planar region for forming the pair of step surfaces forming the positioning portion430edescribed above.

As illustrated inFIG.7, in the present embodiment, the portion of the outer circumferential surface430F other than the fixing portion430ais formed in a cylindrical surface shape. In the present example, a portion of the first region F1of the outer circumferential surface430F corresponds to the fixing portion430aformed in a planar shape. In other words, the first region F1of the outer circumferential surface430F includes a planar portion and a cylindrical surface portion. Also, the lowest portion430dand the second region F2(the guide portion430b) of the outer circumferential surface430F are formed in a cylindrical surface shape continuous with one another. In the present embodiment, the outer circumferential surface430F of the shaft-like portion430, i.e., the outer circumferential surface430F of the cover portion430C in this example, is formed with a portion of the cylindrical surface flattened and the external shape of the cross-section orthogonal to the axial direction L formed in a D shape.

In the present embodiment, the suspension belt421is fastened to the fixing portion430aof the outer circumferential surface430F by a fastening member433. The fastening member433is provided with a bolt433ascrewed into the shaft-like portion430(the shaft S) from the radially outward side while extending through the suspension belt421in the thickness direction and a pressing plate433bdisposed between the head of the bolt433aand the suspension belt421. A female thread into which the bolt433ais screwed is formed in the section corresponding to the shaft-like portion430(the shaft5). The pressing plate433bpresses the suspension belt421against the fixing portion430a(the shaft-like portion430) from the radially outward side as the bolt433ais screwed into the shaft-like portion430. In other words, the suspension belt421is sandwiched between the pressing plate433band the fixing portion430ain the radial direction and fixed. In the present example, the pressing plate433bhas a dimension in the axial direction L that corresponds to the axial direction dimension La of the fixing portion430aand the belt width421W of the suspension belt421(seeFIGS.5and6). Accordingly, at the fixing portion430aof the outer circumferential surface430F, the contact pressure between the suspension belt421and the outer circumferential surface430F of the shaft-like portion430can be easily made uniform in the width direction of the suspension belt421.

As illustrated inFIG.7, in the present embodiment, the fixing portion430ais disposed including a portion at the same height as the axial center Ax of the shaft-like portion430. In other words, the fixing portion430ais disposed intersecting a virtual horizontal plane including the axial center Ax of the shaft-like portion430. In this manner, the fixing portion430acan be disposed at a position relatively far from the lowest portion430dof the outer circumferential surface430F of the shaft-like portion430. This allows a large contact area between the outer circumferential surface430F and the suspension belt421at the lowest portion430dregion to be ensured, which makes the contact pressure between the suspension belt421and the outer circumferential surface430F easy to make uniform in the width direction of the suspension belt421.

Also, inFIGS.4to6, in the present embodiment, the fixing device43is provided with a position changing portion432that rotates the shaft-like portion430about the axial center Ax to change the position of the fixing portion430ain the circumferential direction of the shaft-like portion430. By operating the position changing portion432in this manner, the position of the fixing portion430ain the circumferential direction of the shaft-like portion430can be adjusted. Accordingly, the portion of the suspension belt421extending from the fixing portion430acan be easily adjusted to a state of being uniform with the outer circumferential surface430F of the shaft-like portion430.

As illustrated inFIGS.5and6, in the present embodiment, the position changing portion432is configured with a so-called double nut configuration. To explain further, the shaft S is provided with a large diameter portion S1disposed between the pair of connection portions431and a small diameter portion S2formed with a smaller diameter than the large diameter portion S1disposed on each side of the large diameter portion S1in the axial direction L. Also, a cylindrical bolt432bis disposed covering the outer circumference of the small diameter portion S2, and the small diameter portion S2and the cylindrical bolt432bengage in the circumferential direction via a key432kand integrally rotate. Also, the cylindrical bolt432bis configured to be able to move in the axial direction L relative to the small diameter portion S2. A first female thread portion Fs1that engages with a male thread portion Ms of the cylindrical bolt432bis formed at a portion of the connection portion431where the small diameter portion S2(the shaft S) extends through. Also, a nut432nis disposed adjacent to the connection portion431in the axial direction L. A second female thread portion Fs2that engages with the male thread portion Ms of the cylindrical bolt432bis formed in the inner circumferential surface of the nut432n.

In this manner, the cylindrical bolt432bis restricted from moving in the circumferential direction relative to the small diameter portion S2but can move in the axial direction L. Thus, even with the cylindrical bolt432band the first female thread portion Fs1engaged together, by moving the position in the axial direction L of the cylindrical bolt432brelative to the small diameter portion S2, the shaft S can be rotated without moving the position in the axial direction L of the large diameter portion S1relative to the connection portion431. Accordingly, with the nut432nloosened, the shaft-like portion430can be rotated about the axial center Ax to change the position of the fixing portion430ain the circumferential direction. Also, by tightening the nut432n, the shaft S can be prevented from rotating.

Here, a comparative example of the present configuration is illustrated inFIG.8. In the configuration of the comparative example, the fixing position of a lower end portion200dof a suspension belt200corresponds to a lowest portion201dof a shaft-like portion201. As illustrated inFIG.8, with such a configuration, due to the rigidity or other characteristic of the suspension belt200, the suspension belt200may extend not conforming to an outer circumferential surface201F and being separated from the outer circumferential surface201F. In other words, compared to the present configuration illustrated inFIG.7, in the comparative example illustrated inFIG.8, the position (referred to as a separation position P) where the suspension belt200separates from the outer circumferential surface201F is at or near the lowest portion201dof the outer circumferential surface201F, and thus the area where the suspension belt200comes into contact with the outer circumferential surface201F of the shaft-like portion201is small. Accordingly, in the comparative example, the suspension belt200cannot be disposed conforming to the outer circumferential surface201F of the shaft-like portion201, and the suspension belt200cannot be appropriately fixed. Thus, stress acting in the extension direction of the suspension belt200is likely to act in a non-uniform manner in the width direction of the suspension belt200, causing deflection or twisting in the suspension belt200.

However, in the present configuration, as illustrated inFIG.7, the suspension belt421is fixed in the first region F1of the outer circumferential surface430F of the shaft-like portion430. Also, the suspension belt421extending from the fixing portion430ais disposed running through a lowest portion430dof the outer circumferential surface430F and running along the second region F2and upward. Accordingly, the suspension belt421can be brought into contact with the outer circumferential surface430F in the second region F2from the lowest portion430dof the outer circumferential surface430F of the shaft-like portion430. Also, the separation position P where the suspension belt421extending upward separates from the outer circumferential surface430F in the second region F2is easily set at a height at or near the axial center Ax of the shaft-like portion430. Accordingly, the suspension belt421can be brought into contact with the outer circumferential surface430F of the shaft-like portion430in a relatively large area. Because of this, the contact pressure between the suspension belt421and the outer circumferential surface430F of the shaft-like portion430can be made substantially uniform in the width direction of the suspension belt421. This makes it difficult for the stress acting in the extension direction of the suspension belt421to be non-uniform in the width direction of the suspension belt421, which makes it less likely for the suspension belt421to experience deflection or twisting. Accordingly, the width direction of the suspension belt421can be easily aligned with the horizontal direction, or in other words, the extension direction of the suspension belt421can be easily aligned with the vertical direction. This makes it easy to adjust the length of the suspension belt421. As in the present example, with a configuration in which the holding portion41is suspended by a plurality (three) of the suspension belts421, the length of each one of the plurality of suspension belts421can be easily adjusted. This also makes it easy to adjust the levelness of the suspended holding portion41.

Other Embodiments

Next, an article lift device according to other embodiments will be described.

1. In the embodiment described above, the fixing portion430ais formed in a planar shape. However, the fixing portion430ais not limited to this example and may be formed in a cylindrical surface shape, for example. In this case, all of the outer circumferential surface430F including the first region F1and the second region F2may be formed in a cylindrical surface shape.

2. In the embodiment described above, the outer circumferential surface430F of the shaft-like portion430is formed with a portion of the cylindrical surface flattened and the external shape of the cross-section orthogonal to the axial direction L formed in a D shape. However, the external shape is not limited to this example, and the external shape of the cross-section orthogonal to the axial direction L of the outer circumferential surface430F may be formed in a circular shape, an elliptical shape, a polygonal shape, or the like. Note that in a case where the external shape of the cross-section orthogonal to the axial direction L of the outer circumferential surface430F is a polygonal shape, a polygonal shape with many corners resembling a circular shape is preferable.

3. In the embodiment described above, the fixing portion430ais disposed including a portion at the same height as the axial center Ax of the shaft-like portion430. However, the fixing portion430ais not limited to this example, and the fixing portion430ais only required to be disposed in the first region F1of the outer circumferential surface430F and may not include a portion at the same height as the axial center Ax of the shaft-like portion430. In this case, the fixing portion430a, in the first region F1, is preferably disposed at a position higher than the axial center Ax of the shaft-like portion430, but may be disposed at a position lower than the axial center Ax.

4. In the embodiment described above, the shaft-like portion430is provided with the cover portion430C, and the outer circumferential surface of the cover portion430C corresponds to the outer circumferential surface430F of the shaft-like portion430. However, the shaft-like portion430is not limited to this example and may not be provided with the cover portion430C. In this case, the outer circumferential surface of the portion of the shaft S corresponding to the shaft-like portion430corresponds to the outer circumferential surface430F of the shaft-like portion430.

5. In the embodiment described above, the fixing device43is provided with a position changing portion432that rotates the shaft-like portion430about the axial center Ax to change the position of the fixing portion430ain the circumferential direction of the shaft-like portion430. However, the fixing device43is not limited to this example and may not be provided with the position changing portion432.

6. In the embodiment described above, the article lift device4is provided on the article transport vehicle V. However, the article lift device4described above can be used in various devices for raising and lowering the article8and is not limited to being used in the article transport vehicle V. The article lift device4can be used in a lifter for raising and lowering transportation, for example.

7. Note that the configurations described in the embodiments described above can be used in combination with configurations described in other embodiments as long as inconsistencies are avoided. Also, regarding the other configurations, the embodiments described in the present specification are merely examples in all aspects. Accordingly, various modifications within the range of the present disclosure can be made as appropriate.

Supplement

The article lift device and the article transport vehicle described above will be described below.

An article lift device according to the present disclosure includes:

a holding portion that holds an article;

a lift device that raises and lowers the holding portion with the holding portion being suspended by a suspension belt; and

a fixing device that fixes a lower end portion of the suspension belt to the holding portion, wherein

the fixing device includes a shaft-like portion with an axial direction aligned with a horizontal direction and a connection portion that connects the shaft-like portion and the holding portion together;

the connection portion connects the shaft-like portion and the holding portion together in a manner so that an outer circumferential surface of the shaft-like portion is separated from the holding portion;

a fixing portion where the lower end portion of the suspension belt is fixed is provided on the outer circumferential surface;

in an axial direction view along the axial direction, a region of the outer circumferential surface on one side of a virtual vertical surface running through an axial center of the shaft-like portion is defined as a first region and a region of the outer circumferential surface on the other side of the virtual vertical surface is defined as a second region;

the fixing portion is provided in the first region; and

the suspension belt extending from the fixing portion is disposed running through a lowest portion of the outer circumferential surface and running along the second region and upward.

According to the present configuration, the suspension belt is fixed in the first region of the outer circumferential surface of the shaft-like portion. Also, the suspension belt extending from the fixing portion is disposed running through the lowest portion of the outer circumferential surface and running along the second region and upward. Thus, the tensile load acting on the suspension belt as a result of supporting the weight of the holding portion can press the suspension belt against the lower portion of the outer circumferential surface of the shaft-like portion. Accordingly, the suspension belt can be brought into contact with the outer circumferential surface in the second region from the lowest portion of the outer circumferential surface of the shaft-like portion. Also, the position where the suspension belt extending upward separates from the outer circumferential surface in the second region is easily set at a height at or near the axial center of the shaft-like portion. Thus, according to the present configuration, the suspension belt can be brought into contact with the outer circumferential surface of the shaft-like portion in a relatively large area. Because of this, the contact pressure between the suspension belt and the outer circumferential surface of the shaft-like portion can be made substantially uniform in the width direction of the suspension belt. Thus, according to the present configuration, it is difficult for the stress acting in the extension direction of the suspension belt to be non-uniform in the width direction of the suspension belt, which makes it less likely for the suspension belt to experience deflection or twisting.

Preferably, the fixing portion is formed in a planar shape with a dimension in the axial direction equal to or greater than a belt width of the suspension belt; and a portion of the outer circumferential surface other than the fixing portion is formed in a cylindrical surface shape.

According to the present configuration, because the fixing portion and the suspension belt can be brought into contact flat against one another, the suspension belt can be easily fixed at the fixing portion appropriately. Also, because the portion of the outer circumferential surface other than the fixing portion is formed in a cylindrical surface shape, the suspension belt extending from the fixing portion is easily disposed in a uniform state with the outer circumferential surface. Thus, the contact pressure between the suspension belt and the outer circumferential surface of the shaft-like portion is easier to be made substantially uniform.

Also, preferably, the fixing portion is disposed including a portion at the same height as the axial center.

According to the present configuration, the fixing portion can be disposed at a position relatively far from the lowest portion of the outer circumferential surface of the shaft-like portion. This allows a large contact area between the outer circumferential surface of the shaft-like portion and the suspension belt at the lowest portion region to be ensured, which makes the contact pressure between the suspension belt and the outer circumferential surface of the shaft-like portion easy to approximate uniform in the width direction of the suspension belt. Accordingly, the suspension belt is even less likely to experience deflection and twisting.

Also, preferably, the fixing device is provided with a position changing portion that rotates the shaft-like portion about the axial center and changes a position of the fixing portion in a circumferential direction of the shaft-like portion.

According to the present configuration, by operating the position changing portion in this manner, the position of the fixing portion in the circumferential direction of the shaft-like portion can be adjusted. Accordingly, the portion of the suspension belt extending from the fixing portion can be easily made in a uniform state with the outer circumferential surface of the shaft-like portion.

An article transport vehicle according to the present disclosure includes:

the article lift device according to the configuration described above;

a travel portion connected to the article lift device that travels along a specific travel path; and

a housing portion that houses the holding portion when the holding portion is at a raised position.

According to the present configuration, the article lift device can be suitably used in an article transport vehicle for transferring an article via raising and lowering.

INDUSTRIAL APPLICABILITY

The technology according to the present disclosure can be applied to an article lift device that raises and lowers an article-holding holding portion with the holding portion being in a suspended state, and an article transport vehicle provided with such an article lift device.

REFERENCE SIGNS LIST

V Article transport vehicle

4Article lift device

421W Belt width

421dLower end portion

432Position changing portion

R Travel path

Ax Axial center

L Axial direction

La Axial direction dimension