Item transport device and item storage device

Abstract

To provide an article conveyance device which can detect the weight of an article more accurately, and which is less likely to cause the collapse of cargo.SOLUTION: In an article conveyance device which lifts a holding member from a position below with respect to an article placed being hollow, which scrapes the article by the holding member, and which moves the article conveyance device by rotating travelling wheels, a lifting mechanism uses a motor as power, and no-load time current information and on-load time current information are acquired. The no-load time current information is the information related to a current value supplied to the motor in a specific increase region in the period from the lifting start of the holding member to the contact with the article. The on-load time current information is the information related to a current value supplied to the motor in a specific increase region from the holding member coming into contact with the article till reaching the increase limit. The article conveyance device includes travel speed setting means which sets the rotation speed of the travelling wheels based on the no-load time current information and the on-load time current information.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an article transport device that transports articles, and also to an article storage device that allows articles to be moved inside. [Background technology]

[0002] 2. Description of the Related Art Article storage devices having a function for moving articles are known. The article storage device disclosed in Patent Document 1 includes a platform member on which a plurality of articles are placed, and an article moving device (article transport device) that moves the articles by itself. The platform member has two or more rows of placement members on which articles are placed and a running path. The article moving device has a running wheel that rotates by power, a holding member that holds an article, and a lifting mechanism that raises and lowers the holding member. The article moving device is inserted between the mounting members and can move along the running path by rotating the running wheels. When the holding member is lowered, the holding member sinks below the upper end of the mounting member, and when the holding member is raised, the holding member protrudes above the upper end of the mounting member. After the article moving device is moved under the article, the holding member is raised to scoop up the article with the holding member, the running wheels are rotated to move the article moving device, and the holding member is lowered to move the article to another position on the platform member.

[0003] Here, if the item placed on the item transport device is heavy and the acceleration of the item transport device at the beginning of its travel is large, the movement of the item may not be able to keep up with the movement of the item transport device, causing the item to shift backward. Furthermore, if the article transport device is suddenly stopped while carrying a heavy article, the article may not be able to follow the stopping of the article transport device and may end up shifting forward due to inertia. In the article moving device disclosed in Patent Document 1, when the article is heavy, the moving speed of the article moving device is slowed down to prevent the article from slipping on the holding member.

[0004] The article moving device disclosed in Patent Document 1 detects the current supplied to the motor when lifting the holding member, and detects the weight of the article based on the strength of the current. If the article is light, the moving speed of the article moving device is increased to improve moving efficiency. If the article is heavy, the moving speed of the article moving device is decreased to prevent the article from slipping on the holding member. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-109868 Summary of the Invention [Problem to be solved by the invention]

[0006] The article transport device disclosed in Patent Document 1 has a concern that the weight of an article may be erroneously detected due to the influence of the outside air temperature, the duration of operation, and the like. For example, when the outside temperature is low and the machine is stopped for a long time, such as immediately after work starts in winter, the temperature of the grease inside the machine is low and the viscosity of the grease is high. Therefore, when the lifting mechanism is driven under these conditions, the current flowing through the motor becomes higher than usual. Therefore, under conditions where the outside temperature is low and the stop time is long, the weight of the article may be detected as being heavier than it actually is.

[0007] SUMMARY OF THE INVENTION The present invention focuses on the above-mentioned problems of the prior art, and aims to provide an article transport device that can detect the weight of an article more accurately and is less likely to cause the load to collapse. [Means for solving the problem]

[0008] An aspect for solving the above-mentioned problems is an item transport device having a running wheel that rotates by power, a holding member that holds an item, and a lifting mechanism that raises and lowers the holding member, in which the holding member is raised from a lower position relative to an item placed in midair, the holding member scoops up the item, and the running wheel is rotated to move it, the item transport device being characterized in that the lifting mechanism is powered by a motor, and acquires no-load current information and loaded current information, the no-load current information being information related to the current value supplied to the motor in a specific ascending region from when the holding member starts to rise until it comes into contact with the item, and the loaded current information being information related to the current value supplied to the motor in a specific ascending region from when the holding member comes into contact with the item until it reaches its ascending limit, and the item transport device has a running speed setting means that sets the rotational speed of the running wheel based on the no-load current information and the loaded current information.

[0009] In this embodiment of the article transport device, the holding member is raised from a position below an article placed in midair and the article is scooped up by the holding member. Therefore, the weight of the article is not applied to the motor from the time the holding member starts to rise until it comes into contact with the article. In contrast, the weight of the article is applied to the motor from the time the holding member comes into contact with the article until it reaches its upper limit. On the other hand, regardless of whether an object is present or not, the motor is subjected to loads due to grease and friction within the device. The article transport device of the present invention detects not only loaded current information but also unloaded current information, and corrects the loaded current information, thereby enabling more accurate weight detection. The above-mentioned "period from when the holding member starts to rise until it comes into contact with the article" refers to the range of ascent when no article load is applied. The "specific no-load ascent region" is a specific range within the "range of ascent when no article load is applied," and is part or all of the "range of ascent when no article load is applied." The "period from when the holding member comes into contact with the article until it reaches its ascent limit" refers to the range of ascent when an article load is applied. The "specific loaded ascent region" is a specific range within the "range of ascent when an article load is applied," and is part or all of the "range of ascent when an article load is applied." The travel speed setting means may be provided inside the main body portion in which the holding member and the lifting mechanism are provided, or may be provided externally.

[0010] In the above aspect, it is desirable to obtain information relating to the weight of the article from the no-load current information and the loaded current information, and to set the rotation speed of the running wheels to a low value when the weight of the article is heavy.

[0011] In each of the above aspects, it is desirable to obtain information related to the weight of the item from the no-load current information and the loaded current information, and when the weight of the item is heavy, the deceleration rate when the running speed change means stops the rotation of the running wheels is low and the running wheels are stopped slowly.

[0012] In each of the above aspects, it is desirable that the no-load current information includes information related to the integrated value of the current in a specific rising region or an approximation thereof, and that the loaded current information includes the integrated value of the current in a specific rising region or an approximation thereof.

[0013] In each of the above aspects, it is desirable to obtain information relating to the weight of the article from the ratio of the no-load current information to the loaded current information.

[0014] In the above-described aspect, it is desirable that information relating to the weight of the item can be transmitted to the outside.

[0015] In each of the above aspects, it is desirable to obtain information related to the rotation speed of the motor, and to define a specific increase region depending on the rotation speed of the motor.

[0016] An embodiment of the item storage device comprises a platform member on which a plurality of items are placed, and an item transport device as described above, wherein the platform member has two or more rows of mounting members on which items are placed, and a running path; the item transport device is inserted permanently or temporarily between the mounting members, and can travel on the running path by rotating the running wheels; when the holding members are lowered, they sink below the upper ends of the mounting members, and when the holding members are raised, they protrude above the upper ends of the mounting members; and after moving the item transport device under the items, the holding members can be raised to scoop up the items with the holding members, the running wheels can be rotated to move the item transport device, and the holding members can be lowered to move the items to another position on the platform member. [Effects of the Invention]

[0017] The article transport device of the present invention can detect the weight of articles more accurately, making it less likely for the load to collapse. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view of an article storage device according to an embodiment of the present invention. [Figure 2] 2 is a perspective view showing a part of a stand member of the article storage device of FIG. 1. FIG. [Figure 3] FIG. [Figure 4] 1A and 1B are cross-sectional views of an article transport device, in which FIG. 1A shows a state in which a holding member is raised, and FIG. 1B shows a state in which the holding member is lowered. [Figure 5] FIG. 2 is a block diagram of a control device for the article transport device. [Figure 6] 10(a) to 10(d) are explanatory views showing a process of lifting a holding member of an article transport device. [Figure 7] 10 is a flowchart of a series of operations of the article transport device. [Figure 8] 10 is a graph showing the relationship between the rotation speed (number of pulses) of the lifting motor and the current supplied when the same item is placed on a tray, the tray is placed in midair by the mounting member of the stand member, and the holding member is raised from a lower position to scoop up the tray with the holding member, where (a) shows the relationship under normal conditions, and (b) shows the relationship immediately after work begins. [Figure 9] 10 is a graph showing the relationship between the number of pulses of the lifting motor and the current supplied when the holding member is raised from a lower position relative to a tray placed in midair by the mounting member of the stand member and the tray is scooped up by the holding member, where (a) shows the case when the tray is light in weight, (b) shows the case when the tray is medium in weight, and (c) shows the case when the tray is heavy. [Figure 10] 10(a) to 10(h) are explanatory diagrams showing a series of operations when moving a tray. [Figure 11] FIG. 10 is a diagram showing a mechanism of a lifting mechanism employed in another embodiment of the present invention. [Figure 12] FIG. 10 is a diagram showing a mechanism of a lifting mechanism employed in still another embodiment of the present invention. [Figure 13] FIG. 10 is a diagram showing a mechanism of a lifting mechanism employed in still another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Further embodiments of the present invention will be described below. The article storage device 1 of this embodiment has a stand member 2, an operating device 5, and a plurality of article transport devices 6. As shown in FIG. 1, the stand member 2 is a kind of shelf, and has elongated storage sections 3 arranged in four rows and four stages. The article transport device 6 is located in each of the storage sections 3 of the platform member 2 and travels within each of the storage sections 3 as will be described later. 6 and 10, the contents 57 are placed on a tray 8 and housed in the stand member 2. In this embodiment, the tray 8 and the contents 57 are the articles to be placed on the stand member 2.

[0020] The mount member 2 is a structure in which a pair of mounting members 10a, 10b are arranged parallel to each other at a certain distance. As shown in Fig. 2, the mount member 2 is a structure made up of multiple upright columns 4a and support plates 4b fixed to the columns 4a in a horizontal position.

[0021] In the mount member 2, two mounting members 10a, 10b are fixed as a set to the support column 4a. Each of the mounting members 10a, 10b is a member that is disposed on a support plate 4b and protrudes from above the support plate 4b. The pair of mounting members 10a, 10b are provided in parallel with each other at a distance that can ensure a space 28 for the article transport device 6 to travel and also allows the tray 8 to be placed thereon.

[0022] The mounting members 10a and 10b are specifically long channel steel or C-shaped steel, and have an upper surface plate 11, a lower surface plate 12, and a connecting plate 13 based on the posture shown in Fig. 2, and are steel materials with a concave cross-sectional shape with three sides surrounded by these three and one open side. Furthermore, the mounting members 10a and 10b can have various cross-sectional shapes other than a concave shape. The lower surface plate 12 constitutes the running path. The mounting members 10a and 10b are arranged so that the recesses face each other. The mounting members 10a and 10b extend in the direction in which the tray 8 moves.

[0023] Next, a description will be given of the article transport device 6. The article transport device 6 is made up of a main body 30 and a holding member 31 as shown in FIG. The main body 30 has a lifting member 35, a running member 36, a storage battery (not shown), and a control device 38 housed within a main body case 33. As shown in Fig. 3, the main body case 33 is a low box with an open top and a substantially square planar shape.

[0024] The lifting member 35 constitutes a lifting mechanism that lifts and lowers the holding member 31. As shown in FIG. 3, the lifting member 35 is composed of a pair of rack members 40a and 40b, a roller 41 incorporating a lifting motor, and a driven member 43. As shown in FIG. 4, the rack members 40a, 40b are members having a certain length, and have rack teeth 46 formed on the upper surface at the center in the longitudinal direction. Furthermore, raised portions 51 are provided at both longitudinal ends. The raised portions 51 are formed with inclined surfaces 47 and plateau portions 48 that are continuous with the inclined surfaces 47. The inclined surfaces 47 and plateau portions 48 of the raised portions 51 function as cams.

[0025] The motorized lifting roller 41 has a motor 22 and a reducer 23 built into a cylindrical case 50 (roller). The motorized lifting roller 41 rotates the outer case 50 by driving the motor 22. Gears 52a and 52b are attached to the case 50. In this embodiment, the motor 22 (hereinafter referred to as the lifting motor 22) built into the lifting motor-equipped roller 41 is a DC motor. More specifically, it is a brushless motor with a built-in Hall element. The current value and rotation speed of the lifting motor 22 change depending on the load. That is, when the load is large, the current consumption of the lift motor 22 increases. Also, when the load is large, the rotation speed of the lift motor 22 decreases and the rise in the rotation speed is delayed. The lift motor 22 also has a function of outputting pulses according to the number of revolutions.

[0026] When the lifting motor-incorporating roller 41 is driven, the gears 52a and 52b on the lifting motor-incorporating roller 41 side rotate, and the rack members 40a and 40b engaged with the gears 52a and 52b move linearly. The rollers 53 of the driven member 43 are placed on the raised portions 51 of the rack members 40a and 40b, so that the mounting positions of the rollers 53 change when the rack members 40a and 40b are moved linearly, and the rollers 53, which act as cam followers, move up and down, thereby raising and lowering the driven member 43. That is, as shown in FIG. 4(b), when the roller 53 is in contact with the base of the inclined surface 47 of the raised portion 51, the roller 53 is in the lower position and the driven member 43 is lowered. On the other hand, as shown in FIG. 4(a), when the roller 53 is in contact with the plateau 48 of the raised portion 51, the roller 53 is in the upper position and the driven member 43 is raised. As described above, when the lifting motor-incorporating roller 41 is driven, the rack members 40a and 40b move linearly, and the driven member 43 moves up and down. Limit switches (not shown) that regulate the lower limit position and the lift limit of the driven member 43 are provided near the rack members 40a and 40b.

[0027] As shown in FIG. 3, the traveling member 36 is composed of a traveling motor 60, axles 61 and 62, and a belt 65. The traveling motor 60 is a type of geared motor, and has a motor and a reducer (neither of which are shown) housed inside a cylindrical case 66, with a rotating shaft 67 protruding from one end of the case 66. A gear 68 is attached to the rotating shaft 67. When the traveling motor 60 is rotated, the four wheels 69 provided on the main body case 33 rotate synchronously.

[0028] The holding member 31 is placed on the main body case 33. Since the holding member 31 is simply placed on the main body case 33, the holding member 31 has a degree of freedom relative to the main body case 33 and moves up and down in accordance with the movement of the driven member 43.

[0029] The control device 38 has a built-in transmitter and receiver for wireless communication. The transmitter and receiver transmit and receive signals between the control device 38 and the external operating device 5 (FIG. 1).

[0030] The control device 38 also stores a program that realizes the weight measuring means. The control device 38 also has a current value measuring means that detects the current supplied to the lift motor 22 when lifting the holding member 31, and a rotation speed detecting means that detects the rotation speed of the lift motor 22 when lifting the holding member 31. As described above, the lift motor 22 has the function of outputting pulses according to the rotation speed, and the rotation speed detecting means detects the rotation speed of the lift motor 22 from the origin by integrating the pulses. In other words, the pulses are information related to the rotation speed of the lift motor 22.

[0031] Furthermore, the control device 38 has no-load current integrating means, loaded current integrating means, and weight calculating means for calculating or estimating the weight of the tray 8 (more precisely, the total weight of the tray 8 and the contents 57 thereon, i.e., the weight of the articles) based on these. The control device 38 also has speed setting means. In addition, the control device 38 has braking timing changing means and braking force changing means, which will be described later. The control device 38 also includes a drive motor control circuit that controls the drive motor 60 .

[0032] As described above, one article transport device 6 is provided in each storage section 3 of the stand member 2. As shown in Figure 6, the article transport device 6 is installed in the space 28 sandwiched between the connecting plates 13 of the mounting members 10a and 10b of the stand member 2, and each wheel 69 of the article transport device 6 is placed on the upper surface of the lower plate 12. The lower surface plate 12 constitutes a running path for the platform member 2, and each wheel 69 of the article transport device 6 is in contact with the running path (lower surface plate 12). Therefore, when the travel motor 60 is started to rotate the wheels 69, the article transport device 6 moves linearly in the elongated space 28 surrounded by the mounting members 10a, 10b of the platform member 2.

[0033] Furthermore, when the lifting members 35 of the article transport device 6 are lowered, the holding members 31 are lowered below the upper plates 11 of the mounting members 10a and 10b, as shown in Figure 6(a). Therefore, even if a tray 8 is placed on the mounting members 10a and 10b as shown in Figure 6(a), the holding members 31 of the article transport device 6 do not come into contact with the tray 8. Therefore, the bottom of the tray 8 remains in contact with the upper plates 11 of the mounting members 10a and 10b, and the tray 8 is placed in the air by the mounting members 10a and 10b.

[0034] On the other hand, when the lifting motor 22 is driven to lift the lifting member 35, the holding member 31 rises above the upper surface plates 11 of the mounting members 10a and 10b as shown in FIGS. 6(c) and 6(d). 6(c) and 6(d), if a tray 8 is placed on the upper surface plate 11, the holding member 31 is raised from a position below the tray (article) 8 placed in the air, and the tray 8 is scooped up from the placement members 10a and 10b by the holding member 31 of the article transport device 6. As a result, the tray 8 is separated from the upper surface plate 11 of the placement members 10a and 10b.

[0035] The relationship between the ascending step of the holding member 31 and the tray 8 is as follows. The holding member 31 moves up and down within a range from the lower limit position in FIG. 6(a) to the upper limit position in FIG. 6(d). Therefore, the range from the lower limit position in FIG. 6(a) to the upper limit position in FIG. 6(d) is the rising region. 6(a), the holding member 31 waits at the lowest position. At this time, the holding member 31 is not in contact with the tray 8. When the lifting motor 22 is driven to lift the holding member 31, the holding member 31 comes into contact with the tray 8 as shown in FIG. 6(b). 6(a) to the time when the lifting motor 22 comes into contact with the tray 8 (item 8), the load of the tray 8 (item 8) is not applied to the lifting motor 22. Therefore, the lifting motor 22 is driven in a no-load state with respect to the load based on the load of the item (tray 8).

[0036] After the holding member 31 comes into contact with the tray 8 as shown in Fig. 6(b), if the holding member 31 is further raised, the tray 8 is lifted as shown in Fig. 6(c). Then, as shown in Fig. 6(d), the tray 8 is further lifted and the holding member 31 reaches the upper limit position, at which point the lifting motor 22 stops. After the holding member 31 comes into contact with the tray 8, until the holding member 31 reaches the upper limit position, the weight of the tray (article) 8 is applied to the lifting motor 22. Therefore, the lifting motor 22 is driven in a loaded state with respect to the load based on the weight of the article (tray 8).

[0037] The control device 38 has a built-in CPU, and a computer program for realizing the weight measuring means is written in the CPU. The weight measuring means is provided with computer programs that constitute a current value measuring means, a rotational speed detecting means, a no-load current integrating means, a loaded current integrating means, and a weight calculating means. The speed setting means, the braking timing setting means, and the braking force setting means are also realized by the CPU.

[0038] The control device 38 receives as input the value of the current supplied to the lift motor 22 and consumed by the lift motor 22. The value of the current supplied to the lift motor 22 is then detected by a current value measuring means. Furthermore, a signal from a Hall element (not shown) of the lift motor 22 is input to the control device 38. Then, the pulses output from the lift motor 22 are counted. In this embodiment, the height of the holding member 31 is monitored by the integrated number of pulses output from the lifting motor 22. That is, a pulse signal originating from the Hall element is input to the control device 38, and the height of the holding member 31 is indirectly detected based on the integrated value of the number of pulses. For example, at the lowest position, the integrated value of pulses is 0. At a height where the integrated value of pulses is close to NA, the holding member 31 comes into contact with the tray 8. Hereinafter, the integrated value of pulses will be simply referred to as the number of pulses.

[0039] In this embodiment, a pulse number a corresponding to a position slightly higher than the lower limit position and a pulse number b which is greater than the pulse number a and less than NA, at which the holding member 31 contacts the tray 8, are set. The period between pulse number a and pulse number b is a part of the ascending region, and is a section in which the lift motor 22 is driven in a no-load state with respect to the load based on the weight of the article (tray 8). Also, during this period, the influence of the inrush current of the lift motor 22 is small, and the current value is stable.

[0040] Furthermore, in this embodiment, the number of pulses at which the holding member 31 contacts the tray 8 is set to be a pulse number c that is greater than NA, and a pulse number d that is greater than the pulse number c and smaller than the pulse number corresponding to the upper limit position. The period between pulse number c and pulse number d is a part of the ascending region, and is a section in which the lift motor 22 is driven under load in relation to the load based on the weight of the articles (tray 8). Also, during this period, the influence of overcurrent caused by the lift motor 22 being forcibly stopped is small, and the current value is stable.

[0041] The no-load current integrating means calculates the integrated value of the current supplied to the lift motor 22 between the pulse number a and the pulse number b. The no-load current integrating means may calculate an approximation of the integrated value. The load current integrating means calculates the integrated value of the current supplied to the lift motor 22 between the pulse number c and the pulse number d. The load current integrating means may calculate an approximation of the integrated value.

[0042] The weight calculation means calculates the weight of the item from the integrated value or an approximation of the current calculated by the no-load current integration means and the integrated value or an approximation of the current calculated by the loaded current integration means. Specifically, a value G related to the weight is calculated based on the following formula 1: f(x) is a formula showing the change in the current value.

[0043]

number

[0044] The measurement accuracy of the weight measuring means does not need to be high, and it may be sufficient to classify the weight into several levels such as "lightweight," "medium weight," and "heavy."

[0045] As described above, the weight measuring means calculates the weight of the item from the integrated value of the current calculated by the no-load current integrating means and the integrated value of the current calculated by the loaded current integrating means. Here, in a loaded state, there is a correlation between the integrated value of the current supplied to the lifting motor 22 when lifting the holding member 31 and the weight of the tray 8, which is an item placed on the holding member 31. For example, if the weight of the tray 8 is heavy, the current supplied to the lifting motor 22 increases. Here, if the weight of the tray 8 is heavy, the rotation speed of the lifting motor 22 decreases, which increases the time required to lift the holding member 31, and the amount of current per unit time does not necessarily directly reflect the weight of the tray 8. In contrast, the integrated value of the current more accurately reflects the weight of the tray 8. However, under conditions where the outside temperature is low and the stoppage time is long, such as immediately after work starts in winter, the viscosity of the grease inside the device is high, and the power consumed by friction, etc. is added to the current related to the weight. Therefore, when the holding member 31 is raised under these conditions, the current value flowing through the lifting motor 22 becomes higher than usual, and the integrated value of the current also becomes large.

[0046] In this embodiment, the integrated value of the current calculated by the loaded current integrating means is corrected by the integrated value of the current calculated by the no-load current integrating means, thereby determining the weight of the article more accurately. That is, the integrated value of the current calculated by the no-load current integration means varies depending on the frictional resistance of the device and the like. Specifically, under conditions where the outside temperature is low and the stop time is long, such as immediately after work starts in winter, the integrated value becomes large. Therefore, the value G obtained by dividing the integrated value of the current calculated by the loaded current integrating means by the integrated value of the current calculated by the no-load current integrating means corresponds to the weight of the item. That is, when G is large, the weight of the item is large, and when G is small, the weight of the item is small.

[0047] The graph shown in Figure 8 is a graph showing the relationship between the number of pulses of the lifting motor 22 and the current supplied when the same contents 57 are placed on the tray 8, the tray 8 is placed in midair by the mounting members 10a and 10b of the stand member 2, the holding member 31 is raised from a lower position, and the tray 8 is scooped up by the holding member 31, where (a) shows the relationship under normal conditions, and (b) shows the relationship immediately after work begins.

[0048] As is clear from comparing the two graphs in Figure 8, the current values immediately after work starts are generally inflated compared to the current values during normal operation. Therefore, the area corresponding to the integrated value during load operation, which is the subject of integration, is larger immediately after work starts than during normal operation. Similarly, the area corresponding to the integrated value during no load operation, which is the subject of integration, is larger immediately after work starts than during normal operation. Therefore, the value G obtained by dividing the integrated value under load by the integrated value under no load is not significantly different from that under normal conditions, even immediately after the start of work. The measurement result of the weight measuring means is transmitted to the operating device 5 by the transmitter.

[0049] Next, the steps for detecting the weight of an article by raising the holding member 31 of the article transport device will be described with reference to the flowchart of FIG. In this embodiment, in step 1, the process waits for an instruction to lift the holding member 31. When an instruction to lift the holding member 31 is received, the process proceeds from step 1 to step 2, and the lifting motor 22 is driven. As a result, the holding member 31 rises. During this time, the rotation speed detection means of the control device 38 monitors the number of pulses of the lifting motor 22. In other words, it monitors the height of the holding member 31. Then, in step 3, it waits until the number of pulses reaches a. The height at which the number of pulses corresponds to a is the height at which the holding member 31 leaves the lower limit position.

[0050] When the number of pulses reaches a, the process proceeds from step 3 to step 4, and the no-load current integrating means starts integrating the current value supplied to the lift motor 22. The current value continues to be accumulated until the number of pulses of the lifting motor 22 reaches b. The height corresponding to the number of pulses b is the height immediately before the holding member 31 comes into contact with the tray 8. When the number of pulses output from the lift motor 22 reaches b, the process proceeds from step 5 to step 6, and measurement of the current value is temporarily stopped.

[0051] The holding member 31 continues to rise and comes into contact with the tray 8. From this point, the weight of the tray 8 is applied to the lifting motor 22, causing the amount of current to increase. Then, in step 7, it waits until the number of pulses reaches c. The height corresponding to the number of pulses c is the height immediately after the holding member 31 exceeds the height of the upper surface plate 11 of the mounting members 10a and 10b.

[0052] When the number of pulses reaches c, the process proceeds from step 7 to step 8, where the load current integrating means starts integrating the current value supplied to the lift motor 22. The current value continues to be accumulated until the number of pulses of the lifting motor 22 reaches d. The height corresponding to the number of pulses d is the height just before the upper limit position of the holding member 31. When the number of pulses of the lift motor 22 reaches d, the process proceeds from step 9 to step 10, and measurement of the current value is temporarily stopped.

[0053] The holding member 31 continues to rise and reaches the upper limit. In step 11, when it is confirmed that the holding member 31 has reached the upper limit, the lifting motor 22 is stopped.

[0054] Next, the weight of the item is calculated based on the integrated value when loaded and the integrated value when unloaded. Specifically, the weight of the item is determined by the value G obtained by dividing the integrated value when loaded by the integrated value when unloaded.

[0055] Then, the process proceeds to step 14, where a conveying speed, braking timing and braking force appropriate for the weight of the article are set. That is, the control device 38 has a speed determining means, a braking force setting means and a braking timing setting means. The speed determination means functions as a traveling speed change means that changes the rotation speed of the wheels (traveling wheels) 69 depending on conditions, and determines the rotation speed of the wheels (traveling wheels) 69. More specifically, it determines the rotation speed of the motor built into the traveling motor 60. In this embodiment, the speed determination means determines the rotation speed of the traveling motor 60 based on the measurement result of the weight measurement means. The braking force setting means changes the braking force of the wheels (traveling wheels) 69 depending on the conditions. The braking timing change means is a function that stops the article transport device 6 near an existing article, and changes the timing at which braking begins.

[0056] In this embodiment, the rotation speed of the travel motor 60 is divided into three stages, and when the weight of the tray 8 is light, the travel motor 60 rotates at high speed to move the item transport device 6 at high speed. When the weight of the tray 8 is light, the item transport device 6 is moved at high speed, and then strongly braked to a relatively sudden stop.

[0057] On the other hand, if the weight of the tray 8 is medium, the travel motor 60 is rotated at a medium speed, and the article transport device 6 is moved at a medium speed. Also, if the weight of the tray 8 is medium, the article transport device 6 is moved at a medium speed, and then a medium amount of braking is applied to stop the article transport device 6 relatively slowly.

[0058] When the weight of the tray 8 is heavy, the travel motor 60 is rotated at a low speed to move the article transport device 6 at a low speed. When the weight of the tray 8 is heavy, the article transport device 6 is moved at a low speed, and then a weak brake is applied to stop the article transport device 6 relatively slowly. In this manner, in this embodiment, the acceleration, travel speed during cruising, braking strength and braking timing of the article transport device 6 are changed based on the measurement results of the weight measuring means.

[0059] Next, a series of operations of the item storage device 1 of this embodiment will be described. In this embodiment, a tray 8a on which contents 57 are placed by a forklift, crane, elevator, etc. (not shown) is placed at the starting end of the elongated storage section 3 of the stand member 2 as shown in Figure 10(a). 10(a) illustrates a state in which another tray 8b has been previously accommodated in the storage section 3. The previously accommodated tray 8b has an item 57 placed on it. The previously accommodated tray 8b is located at the back of the elongated storage section 3.

[0060] In the article storage device 1 of this embodiment, the article transport device 6 arranged in the storage section 3 is caused to travel so that the article transport device 6 slides under the newly stored tray 8a. Specifically, with the holding member 31 lowered, the travel motor 60 is started to travel the article transport device 6 until the article transport device 6 slides under the tray 8a as shown in FIG. 10(b).

[0061] Then, the lifting motor 22 is started to lift the holding member 31. Here, the article transport device 6 is located below the tray 8a, and the tray 8a is located in a hollow position above the holding member 31, so that the holding member 31 lifts up the tray 8a. In this embodiment, the current value measuring means detects the current supplied to the lifting motor 22 when the tray 8a is lifted by raising the holding member 31. Then, the weight measuring means calculates the weight of the tray 8 based on the integrated value of the current value detected by the current value measuring means.

[0062] For example, when the weight of the tray 8a is light, the integrated value of the current supplied to the lifting motor 22 detected by the current value measuring means is small as shown in FIG. 9(a). The value G obtained by dividing the integrated value of the current calculated by the loaded current integrating means by the integrated value of the current calculated by the no-load current integrating means is small. If the value G obtained by dividing the integrated value of the current calculated by the loaded current integrating means by the integrated value of the current calculated by the no-load current integrating means is small, it is determined that the weight of the tray 8 is light.

[0063] On the other hand, when the weight of the tray 8a is medium, the integrated value of the current supplied to the lifting motor 22 detected by the current value measuring means is medium as shown in FIG. 9(b). On the other hand, the integrated value of the current calculated by the no-load current integration means is not significantly different from that when the weight of the article is light as shown in FIG. 9(a). Therefore, when the weight of tray 8a is medium, the value G obtained by dividing the integrated value of the current calculated by the loaded current integrating means by the integrated value of the current calculated by the no-load current integrating means is medium.When the value G obtained by dividing the integrated value of the current calculated by the loaded current integrating means by the integrated value of the current calculated by the no-load current integrating means is medium, the weight of tray 8 is determined to be medium.

[0064] When the weight of the tray 8a is heavy, the integrated value of the current supplied to the lifting motor 22 detected by the current value measuring means becomes large as shown in FIG. 9(c). On the other hand, the integrated value of the current calculated by the no-load current integration means is not significantly different from that when the weight of the article is light as shown in FIG. 9(a). Therefore, if the weight of tray 8a is large, the value G obtained by dividing the integrated value of the current calculated by the loaded current integrating means by the integrated value of the current calculated by the no-load current integrating means becomes large. If the value G obtained by dividing the integrated value of the current calculated by the loaded current integrating means by the integrated value of the current calculated by the no-load current integrating means is large, it is determined that the weight of tray 8 is large.

[0065] Returning to the explanation of Figure 10, as described above, the item transport device 6 is placed under the tray 8a (Figure 10b), and the lifting motor 22 is started to raise the holding member 31, thereby scooping up the tray 8a from the placement members 10a and 10b as shown in Figure 10(c). Then, power is applied to the travel motor 60 to rotate the wheels (travel wheels) 69, and the article transport device 6 travels with the tray 8a still placed on the holding member 31, as shown in Figures 10(d) to (f). When the article transport device 6 approaches the preceding tray 8b, the travel motor 60 is braked, as shown in Figure 10(g), and the article transport device 6 stops next to the preceding tray 8b.

[0066] In this embodiment, the travel pattern of the article transport device 6 is changed based on the measurement results of the weight measurement means.

[0067] That is, when the tray 8 is light, the article transport device 6 is started with relatively rapid acceleration, and the article transport device 6 is caused to travel at high speed. Then, just before the preceding tray 8b, the travel motor 60 is braked, and the article transport device 6 is stopped next to the preceding tray 8b. That is, when the tray 8 is light, the speed determining means selects a running pattern of sudden start, high speed running, or sudden stop, and the running motor 60 is driven in accordance with this running pattern.

[0068] If the weight of the tray 8 is medium, the article transport device 6 is started with medium acceleration and travels at a medium speed. Then, the travel motor 60 is braked slightly ahead of the preceding tray 8b, and the article transport device 6 is stopped next to the preceding tray 8b. That is, when the weight of the tray 8 is medium, the speed determining means selects a running pattern of medium starting, medium speed running, and medium-moderate braking, and the running motor 60 is driven in accordance with this running pattern.

[0069] If the weight of the tray 8 is heavy, the article transport device 6 is started with gentle acceleration and then travels at a low speed. Then, the travel motor 60 is braked well in front of the preceding tray 8b, and the article transport device 6 is stopped next to the preceding tray 8b. That is, when the tray 8 is heavy, the speed determining means determines the running pattern of slow start, slow running, slow stop. A running pattern is selected, and the running motor 60 is driven in accordance with this running pattern. That is, when the tray 8 is heavy, the speed, acceleration rate and deceleration rate during cruising are all reduced.

[0070] According to one of the travel patterns, article transport device 6 is run with tray 8a remaining on holding member 31, and article transport device 6 is stopped next to tray 8b, which has been stored first, as shown in Figure 10(g). After that, as shown in Figure 10(h), lifting motor 22 is started to lower holding member 31, and tray 8a is transferred from holding member 31 to placement members 10a, 10b. That is, the holding member 31 is lowered below the placement members 10a and 10b, and the holding member 31 is separated from the tray 8a. Thereafter, the article transport device 6 is caused to travel and heads toward transporting a new tray 8.

[0071] In the embodiment described above, a lifting mechanism is employed in which the linear motion of rack members 40a, 40b is converted into vertical motion by a cam, thereby raising and lowering holding member 31. This configuration is recommended as it allows the overall height of article transport apparatus 6 to be kept low. However, the present invention is not limited to this configuration, and the holding member 31 may be raised and lowered by a cam or screw of another structure. For example, a lifting mechanism may be employed in which a cam 75 as shown in FIG. 11 is rotated by a motor and a part of the cam 75 is brought into direct contact with the holding member 31 to lift and lower the holding member 31.

[0072] Alternatively, as shown in Fig. 12, an elevating mechanism 77 may be used in which an elevating rod 76 is raised and lowered, and the holding member 31 is raised and lowered by the elevating rod 76. In the elevating mechanism 77 shown in Fig. 12, a screw 74 is formed on the elevating rod 76, and the screw 74 of the elevating rod 76 engages with an internally threaded member 78. A gear is formed on the outer periphery of the internally threaded member 78. Meanwhile, a gear 98 is also attached to the elevating motor 79, and the gear 98 is rotated by the elevating motor 79. The gear 98 on the elevating motor 79 side engages with the gear on the outer periphery of the internally threaded member 78. The female screw member 78 is fixed so as not to be able to move up and down, and the lifting rod 76 is supported so as not to be able to rotate. In the lifting mechanism 77 shown in FIG. 12, the female screw member 78 is rotated by the lifting motor 79, and the lifting rod 76 engaged with the female screw member 78 is raised and lowered, thereby raising and lowering the holding member 31.

[0073] 13, a lifting mechanism may be used in which a rack 96 is formed on a lifting rod 95 and a pinion 99 rotated by a motor 97 is engaged to lift the holding member 31.

[0074] In the above embodiment, the article transport device 6 moves only in a linear direction, but it may also have a function of moving in the X and Y directions.

[0075] In the above-described embodiment, the weight of the articles (the total of the contents 57 and the tray 8) is divided into three levels: "light," "medium," and "heavy," but it may also be divided into two levels. It may also be divided into more levels. It may also be divided into no levels. In the embodiment described above, the running speed of the item conveying device 6 is increased when the weight of the item is "light," but when the weight of the item is extremely light and the contents are prone to rolling or slipping, it is desirable to slow down the running speed of the item conveying device 6.

[0076] In the embodiment described above, pulse numbers a and b are set, and the current value in the no-load state is accumulated only in the region between pulse numbers a and b, but the current value in the entire no-load state may also be accumulated. Similarly, pulse numbers c and d are set, and the current value in the loaded state is integrated only in the region between pulse numbers c and d, but the current value in the entire loaded state may also be integrated.

[0077] In the embodiment described above, pulses based on the signal from the Hall element are obtained as information related to the rotation speed of the lift motor 22, and the height of the holding member 31 is monitored based on the rotation speed of the motor. The information related to the rotation speed of the lift motor 22 is not limited to the signal from the Hall element. For example, a rotary encoder may be attached to the motor, and the information related to the rotation speed of the lift motor 22 may be obtained by the rotary encoder. Furthermore, the height of the holding member 31 may be detected regardless of the number of rotations of the motor. For example, the height of the holding member 31 may be detected by a limit switch, an optical sensor, or the like.

[0078] In the embodiment described above, the weight of the item is determined by the value G obtained by dividing the integrated value of the current calculated by the loaded current integrating means by the integrated value of the current calculated by the no-load current integrating means. However, the weight of the item may also be determined by subtracting the integrated value of the current calculated by the no-load current integrating means from the integrated value of the current calculated by the loaded current integrating means. [Explanation of symbols]

[0079] 1 Article storage device 2 Mounting members 6. Item transport device 8 trays 10a, 10b Mounting member 12 Bottom plate (traveling path) 22, 79 Lifting motor 31 Retaining member 35 Lifting member 38 Control Device 57 Contents 69 Wheels (running wheels)

Claims

1. An article transport device having a running wheel that rotates by power, a holding member that holds an article, and a lifting mechanism that lifts and lowers the holding member, An article transport device that lifts a holding member from a lower position relative to an article placed in the air, scoops up the article with the holding member, and rotates a running wheel to move the article, The lifting mechanism is powered by a motor, Acquire no-load current information and load current information; the no-load current information is information relating to a current value supplied to the motor in a specific ascending region from when the holding member starts to ascend until when the holding member comes into contact with the article, the load current information is information relating to a current value supplied to the motor in a specific lift region from when the holding member contacts the article to when the holding member reaches its lift limit, a running speed setting means for setting the rotation speed of the running wheels based on the no-load current information and the loaded current information; The no-load current information is a no-load current integrated value, which is an integrated value of current, The on-load current information is an on-load current integrated value, which is an integrated value of current, and The rotation speed of the running wheels is set as follows: A value obtained by dividing the integrated current value under load by the integrated current value under no load, or The value obtained by subtracting the integrated current value when no load is applied from the integrated current value when loaded An article transport device characterized in that the weight of an article is determined based on the above.

2. 2. An article transport device according to claim 1, wherein information relating to the weight of an article is obtained from no-load current information and loaded current information, and the rotation speed of the running wheels is set low when the weight of the article is heavy.

3. An article transport device as described in claim 1 or 2, characterized in that information related to the weight of the article is obtained from no-load current information and loaded current information, and when the weight of the article is heavy, the deceleration rate when the running speed change means stops the rotation of the running wheels is low, and the running wheels are stopped slowly.

4. 4. The article transport device according to claim 1, wherein information relating to the weight of the article can be transmitted to an external device.

5. 5. An article transport device according to claim 1, wherein information relating to the rotation speed of the motor is acquired, and a specific rising region is determined depending on the rotation speed of the motor.

6. a platform member on which a plurality of articles are placed, and the article transport device according to any one of claims 1 to 5, the platform member has two or more rows of placement members on which articles are placed and a running path; The article transport device is adapted to be placed between the mounting members either permanently or temporarily, and is capable of traveling along the travel path by rotating the running wheels, and when the holding member is lowered, the holding member sinks below the upper end of the mounting member, and when the holding member is raised, the holding member protrudes above the upper end of the mounting member, This article storage device is characterized in that it is possible to move an article transport device under an article, then raise a holding member to scoop up the article with the holding member, rotate a running wheel to move the article transport device, and lower the holding member to move the article to another position on a platform member.

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