Electric lifting device and control method for electric lifting device

Abstract

The challenge is to prevent damage to electric lifting devices that move items up and down vertically using a motor. [Solution] An electric lifting device 1 comprises a lifting operation unit 16, a motor unit 11, a position detection unit 13, and a control unit 10. The lifting operation unit 16 lifts and lowers an article 7 by winding it up and unwinding it via a link chain 4 through a locking member 6. The motor unit 11 rotates the lifting operation unit 16. The control unit 10 calculates the current command value to the motor unit 11 when the link chain 4 is unwound. If the calculated current command value exceeds a limit range defined by at least one of predetermined positive / negative values, the control unit 10 controls the motor unit 11 to reverse rotation and then hold the link chain 4.

Description

Technical Field

[0001] The present invention relates to an electric lifting device that is used in manufacturing and assembly equipment in the manufacturing field, transfer equipment in the transportation field, etc., and vertically moves an article up and down by an electric motor.

Background Art

[0002] Conventionally, in factories that assemble industrial products, a cargo handling machine that suspends and vertically moves cargo such as tools, work equipment, products, and semi-finished products having a large weight is used. Among them, a lifting device that generates assistance so that a user can vertically move a heavy cargo to an arbitrary height with a relatively light operating force is known to be one using compressed air and one using an electric motor.

[0003] The one using an air cylinder is mainly an arm type, and since compressed air is required, an air compressor or the like is separately required, and there is also a problem that a safety device when the air supply is cut off is required. Further, when suspending cargos of different weights, the degree of assistance changes due to the weight difference. Therefore, in order to correct this, if the air pressure is manually adjusted each time, the work efficiency decreases. If the cargo weight is registered in a computer and carried out by registration call, the configuration becomes complicated including piping because an electro-pneumatic regulator is used.

[0004] On the other hand, for a lifting device using an electric motor, a suspension type that suspends an article with a rope or a chain is known, and a balance type electric lifting device that winds a rope or a chain around a winding drum and balances the weight by assistance of a motor in the vertical up and down direction and moves up and down with a slight operating force is known.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] In electric lifting devices that use link chains to suspend and raise or lower items, a method has been proposed to solve the problem of link chains becoming entangled in a chain bucket located on the side of the link chain opposite to the side that suspends the item (Patent Document 1). When the link chain is wound up and the item rises, the link chain is stored in this chain bucket. When the item descends, the link chain is unwound from the chain bucket. As the link chain is used, wear progresses, and it may become clumped together instead of being aligned in a straight line, causing jamming. Also, the application of lubricants to prevent wear on the link chain can cause dirt and foreign matter to adhere to the link chain, which can also cause a similar jamming phenomenon. Therefore, there was room for improvement from a control perspective in preventing damage to the electric lifting device due to link chain jamming.

[0007] In view of these problems, the present invention aims to prevent damage to link chain type electric lifting devices used to move heavy objects up and down. [Means for solving the problem]

[0008] The electric lifting device of the present invention aims to achieve the above objectives, An electric lifting device comprising a lifting mechanism, a motor, and a control unit for raising and lowering a suspended article, The lifting mechanism raises and lowers the item by winding it up via a link chain through a locking member and then unwinding it. The motor unit performs rotational drive for the lifting mechanism. The control unit is The system calculates the current command value for the motor unit. If the calculated current command value exceeds a limit range defined by at least one of predetermined positive / negative values, it controls the motor unit to reverse rotation and then holds the link chain.

[0009] The electric lifting device of the present invention aims to achieve the above objectives, An electric lifting device for raising and lowering a suspended article, comprising a lifting operation unit, a motor unit, a weight detection unit, and a control unit, The lifting mechanism raises and lowers the item by winding it up via a link chain through a locking member and then unwinding it. The motor unit performs rotational drive for the lifting mechanism. The weight detection unit detects the weight applied to the lifting mechanism and transmits it to the control unit. The control unit is The motor unit can perform balance control by obtaining a weight value from the weight detection unit and balancing the force applied to the locking member by the lifting / lowering unit with the vertically downward force applied to the locking member, thereby bringing the locking member into a balanced state at any desired position. The system calculates the current command value for the motor unit. If the calculated current command value exceeds a limit range defined by at least one of the predetermined positive / negative values ​​derived from the weight values ​​used for balance control, the system controls the motor unit to reverse rotation and then holds the link chain.

[0010] Furthermore, if the calculated current command value exceeds the limit range, the control unit commands the motor unit to use a predetermined value on the excess side as the command value, and then controls the motor unit to rotate in the reverse direction.

[0011] The control method for the electric lifting device of the present invention, in order to achieve the above objective, A control method for an electric lifting device that raises and lowers a suspended article, comprising a lifting mechanism, a motor, and a control unit, The lifting mechanism raises and lowers the item by winding it up via a link chain through a locking member and then unwinding it. The motor unit performs rotational drive for the lifting mechanism. The control unit is The steps include: calculating the current command value for the motor section, The steps include determining whether the calculated current command value exceeds a limit range defined by at least one of the predetermined upper / lower limits, If the calculated current command value exceeds the limit range, a step of rotating the motor unit in the reverse direction; a step of stopping and holding the rotation of the motor unit; are executed.

[0012] The control method of the electric lifting device of the present invention is to be a control method of an electric lifting device that includes a lifting and lowering operation unit, a motor unit, a weight detection unit, and a control unit and lifts and lowers an object suspended therebelow, The lifting and lowering operation unit winds up an object through a locking member by a link chain and performs lifting and lowering by feeding it out, The motor unit performs rotational driving of the lifting and lowering operation unit, The weight detection unit detects the weight applied to the lifting and lowering operation unit and transmits it to the control unit, The control unit obtains a weight value from the weight detection unit, and can perform balance control to balance the force on the locking member generated by the lifting and lowering operation unit and the vertically downward force applied to the locking member at an arbitrary position by the motor unit, a step of calculating a current command value for the motor unit; a step of determining whether the calculated current command value exceeds a limit range defined by at least one of predetermined upper / lower limit values; When the calculated current command value exceeds the limit range, a step of rotating the motor unit in the reverse direction; a step of stopping and holding the rotation of the motor unit; are executed.

Advantages of the Invention

[0013] According to the present invention, it is possible to prevent damage to the electric lifting device due to jamming of the link chain.

Brief Description of the Drawings

[0014] [Figure 1] It is a perspective configuration diagram of an electric lifting device according to an embodiment of the present invention. [Figure 2] It is a perspective configuration diagram of an electric lifting device according to an embodiment of the present invention with a part omitted. [Figure 3] This is a perspective view diagram showing a part of the electric lifting device according to an embodiment of the present invention, with some parts omitted. [Figure 4] This is a control block diagram of an electric lifting device according to an embodiment of the present invention. [Figure 5] This is an operation flowchart of an electric lifting device according to an embodiment of the present invention. [Figure 6] This is an operation flowchart of an electric lifting device according to an embodiment of the present invention. [Figure 7] This is a schematic diagram illustrating the operation of an electric lifting device according to an embodiment of the present invention. [Figure 8] This is a schematic diagram illustrating the operation of an electric lifting device according to an embodiment of the present invention. [Figure 9] This is a schematic diagram illustrating the operation of an electric lifting device according to an embodiment of the present invention. [Modes for carrying out the invention]

[0015] Hereinafter, an electric lifting device according to an embodiment of the present invention will be described in detail based on the drawings.

[0016] Figure 1 is a perspective view showing the external configuration of an electric lifting device 1 according to an embodiment of the present invention. The electric lifting device 1 comprises a main body 2, a suspension hook 3, a link chain 4, a chain bucket 17, and an operation command unit 9. The main body 2 is covered with a cover that protects the interior from the outside. The suspension hook 3 is a hook for suspending the main body 2 from a structure or the like. The link chain 4 can suspend an article 7 via a locking member 6. The locking member 6 is connected to one end of the link chain 4. The chain bucket 17 houses a portion of the hoisted link chain 4 at the other end (unloaded side) of the link chain 4. The operation command unit 9 provides operation commands for the electric lifting device 1.

[0017] Figure 2 shows a part of the interior of the main body 2 of the electric lifting device 1 according to an embodiment of the present invention, and is a representation that omits a part of the main body 2 shown in Figure 1.

[0018] The motor unit 11 consists of a motor and a transmission attached to the load side of the motor. The motor is, for example, a servo motor. The transmission reduces the rotational speed of the motor to a predetermined speed. The transmission is, for example, a harmonic drive reducer. The harmonic drive reducer consists of a wave generator with an elliptical outer circumference, an elastically deformable flexspline with numerous external teeth formed on its outer circumference and fitted onto the wave generator so that the position in which it is deflected in the circumferential direction changes as the wave generator rotates, and a circular spline on the outer circumference side of the flexspline that has internal teeth that engage with the external teeth of the flexspline. The power is taken out by a rotating output shaft 15 to which the flexspline is connected as a rotational output, and the motor unit 11 rotates to drive the lifting and lowering mechanism 16.

[0019] By using a gearbox with minimal backlash, such as a harmonic drive gearbox, when frequently switching between forward and reverse rotation of the motor to perform assistive operation, it is possible to eliminate the uncontrollable region during switching and achieve a smooth operating feel. The rotating output shaft 15 is a rotating shaft that has been reduced in speed by the gearbox, and is connected to the lifting and lowering mechanism 16, which rotates the lifting and lowering mechanism 16 continuously in forward and reverse directions.

[0020] A suspension hook 3 for suspending the electric lifting device 1 is fixed to the top surface of the main unit 2. This suspension hook 3 is positioned horizontally and close to the center of gravity of the electric lifting device 1.

[0021] The link chain 4 consists of oval rings, each comprising a semi-circular section and a straight section connected to it, which intersect and are linked alternately. One end is connected to the locking member 6, and the other end (unloaded side) is housed in the chain bucket 17.

[0022] The locking member 6 is used to lock and suspend the article 7, and in this embodiment, a hook-shaped locking member connected to the link chain 4 is used. The locking member 6 is not limited to a hook and can be appropriately selected depending on the shape of the article 7 to be locked.

[0023] The lifting mechanism 16 consists of a rotating member that rotates due to power transmission from the motor unit 11 of the drive source, and a link chain 4 connected to the locking member 6. In this embodiment, the rotating member of the lifting mechanism 16 is cylindrical in shape and is connected to the rotating output shaft 15, which extends and retracts the link chain 4. The position where the link chain 4 is wound is approximately vertically below the suspension hook 3 and is located close to the center of gravity of the main device 2. The link chain 4 is fitted into a pocket groove provided in the rotating member and wound around approximately 180 degrees.

[0024] A position detection unit 13, which detects the rotational angle position of the motor, is connected to the motor unit 11 on the non-load side. The position detection unit 13 is, for example, an absolute encoder, which optically detects the rotational angle position of the motor and outputs a position signal. This position detection unit 13 can detect the extension position, i.e., the lifting position, of the locking member 6.

[0025] In this embodiment, the position detection unit 13 is located on the non-load side of the motor unit 11, but it is not limited to this, and may be provided on the rotating output shaft 15, which is the output of the reduction gear, or on the lifting and lowering operating unit 16, or on both. Furthermore, it is not limited to optical type, but may also be magnetic type, capacitive type, etc.

[0026] The weight detection unit 12 is equipped with a strain generating body and strain gauges attached to the strain generating body so as to detect the force transmitted from the link chain 4 wrapped around the lifting and lowering mechanism 16 as a reaction force. The strain gauges are incorporated into a Wheatstone bridge circuit that converts the strain generated in the strain generating body according to the weight into an electrical signal, and the weight detection unit 12 outputs a weight signal. One end of the weight detection unit 12 is connected to a suspension hook 3, and the other end is used to suspend the lifting and lowering mechanism 16, the rotating output shaft 15, the motor unit 11, and the position detection unit 13.

[0027] The weight detection unit 12 is not limited to this; it is sufficient if it can detect the weight applied to the locking member 6. It may also be a rotary torque sensor that detects torque from the twist of a rotating output shaft 15 installed between the reduction gear and the lifting operation unit 16, or a drum-shaped structure installed between the casing of the motor unit 11 and the fixing member of the main unit 2 to detect the reaction force received by the motor unit 11. Alternatively, it may be placed near the locking member 6 in a load cell configuration and transmit the weight signal to the main unit 2 via wired or wireless connection.

[0028] The control unit 10 is located inside the main unit 2 near the lifting mechanism 16. The control unit 10 includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), other storage devices, and input / output devices. The control unit 10 controls the motor unit 11 based on the position signal from the position detection unit 13 and the weight signal from the weight detection unit 12. The electrical components, including the control unit 10, are located inside the main unit 2, which is covered with a cover, so that the electric lifting device 1 can be used in places where it may be exposed to powder or water droplets.

[0029] The operation command unit 9 has, for example, a balance button 21, a holding button 22, an upward button 23, and a downward button 24 as operating means. The operation command unit 9 and the control unit 10 are connected wirelessly using infrared or the like. The operation buttons of the operation command unit 9 consist of a balance button 21 that balances the item 7 suspended from the locking member 6, a holding button 22 that maintains the current position of the locking member 6, an upward button 23 that raises the locking member 6 electrically, and a downward button 24 that lowers the locking member 6 electrically. Each of these operation buttons of the operation command unit 9 informs the operator when it has been pressed by emitting light. Details of the operation will be described later.

[0030] With the above configuration, when an item 7 is suspended from the locking member 6, the weight of the item 7 pulls the link chain 4, causing the weight detection unit 12 to also be pulled downwards via the locking member 6, link chain 4, lifting mechanism 16, rotating output shaft 15, and motor unit 11. The strain-generating part of the weight detection unit 12 deforms, and the control unit 10 calculates the load applied to the lifting mechanism 16 based on the load signal detected by the strain gauge attached to the strain-generating part, and controls the motor unit 11 to assist in balancing the item 7. In other words, the control unit 10 controls the motor unit 11 so that the force applied to the locking member 6 by the lifting mechanism 16 balances the vertically downward force applied to the locking member 6, bringing the locking member 6 and the item 7 into a balanced state at any desired position. Of course, the control unit 10 can raise and lower the item 7 while balancing it by having the operator apply a slight external force in either the up or down direction to the item 7 or the locking member 6, and when the operator stops applying the external force, it can stop the item 7 or the locking member 6 while balancing it at that position.

[0031] Figure 3 is a diagram showing a partially omitted configuration of an electric lifting device according to an embodiment of the present invention. Figure 3 shows details of the parts related to the lifting operation unit 16 and the link chain 4.

[0032] Here, link chain 4a indicates the unloaded side of link chain 4, and link chain 4b indicates the loaded side of link chain 4 to which the locking member 6 is connected. Link chain 4 is wrapped around the body of the lifting mechanism 16 by approximately 180 degrees. Winding and unwinding of link chain 4 is performed by a motor unit 11 connected to a rotating output shaft 15. Chain guides 19b and 19d, located vertically downward from near the starting position where link chain 4a is wrapped around the lifting mechanism 16, guide link chain 4a so that it fits into the chain pocket of the lifting mechanism 16. Similarly, chain guides 19a and 19c, located vertically downward from near the starting position where link chain 4b is wrapped around the lifting mechanism 16, guide link chain 4b so that it fits into the chain pocket of the lifting mechanism 16. Link chain 4b is then stored in the chain bucket 17.

[0033] Figure 4 is a block diagram of the control of an electric lifting device 1 according to an embodiment of the present invention. The electric lifting device 1 is composed of a main unit 2 and an operation command unit 9.

[0034] The control unit 10 of the main unit 2 controls the entire main unit 2. The control unit 10 of the main unit 2 has a storage unit 10f that stores information necessary for controlling the electric lifting device 1. The control unit 10 of the main unit 2 also includes a drive circuit that drives the motor unit 11. The control unit 10 of the main unit 2 receives the weight value applied to the lifting operation unit 16 from the weight detection unit 12, receives the rotation angle position value of the motor unit 11 from the position detection unit 13, and transmits and receives signals with the main unit transmitting / receiving unit 14. The main unit transmitting / receiving unit 14 and the control unit 10 of the main unit 2 are connected by a wire, and transmit and receive signals at high speed with extremely short time intervals. The control unit 10 also includes a weight registration means 10a, a balance control means 10b, a speed control means 10c, a current command value calculation means 10d, and a current command value determination means 10e.

[0035] The main unit's transceiver unit 14 communicates wirelessly with the operation command transceiver unit 25 of the operation command unit 9. The main unit's transceiver unit 14 and the operation command transceiver unit 25 are composed of electronic circuits that perform wireless communication and have a radio wave transmitter and receiver, as well as possibly having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc.

[0036] The operation command control unit 20 controls the entire operation command unit 9. The operation command control unit 20 receives operation commands from each operation means (operation buttons) and transmits the operation command signal to the operation command transmission / reception unit 25. The operation command transmission / reception unit 25 then wirelessly transmits the operation command received from the operation command control unit 20 to the main unit transmission / reception unit 14. This signal containing the command is accompanied by identification information of the operation command unit 9 for pairing with the main unit 2.

[0037] Next, the roles of each operation button, which is an operating means provided in the operation command unit 9, will be explained. Each operation button is, for example, a momentary push switch, which turns ON while pressed and self-resets to OFF when released. When an operator presses the balance button 21, a balance command is transmitted from the operation command unit 9, and the control unit 10 of the main unit 2 receives this and starts balance control. When the control unit 10 of the main unit 2 receives the balance command from the operation command unit 9, the weight detection unit 12 detects the weight value applied to the lifting operation unit 16 and stores the output weight value as a registered value in the weight registration means 10a. After this, the balance control means 10b in the control unit 10 of the main unit 2 receives the weight value (load) applied to the lifting operation unit 16 from the weight detection unit 12, calculates the control value so that it is equal to the registered value stored in the weight registration means 10a, and controls the motor unit 11. In this invention, this control is called balance control, and during the period when the control unit 10 of the main unit 2 is performing balance control, the components below the locking member 6 (locking member 6 and article 7) are in a balanced state. In other words, the control unit 10 of the main unit 2 controls the motor unit 11 by calculating that the tension of the link chain 4 caused by the registered weight and the tension of the link chain 4 caused by the weight detected by the weight detection unit 12 are the same, and this control is balance control. When an operator applies a vertically downward external force to the locking member 6 or article 7 during this balance control, the weight applied to the lifting operation unit 16 increases, so the control unit 10 of the main unit 2 calculates a control value to bring it closer to the registered weight, and further controls the motor unit 11 in the direction of extending the link chain 4, causing the locking member 6 and article 7 to descend. On the other hand, if the operator applies an upward vertical force to the locking member 6 or the item 7 during this balance control, the weight applied to the lifting mechanism 16 decreases. The control unit 10 of the main unit 2 then calculates a control value to bring this value closer to the registered weight and further controls the motor unit 11 in the direction of winding up the link chain 4, causing the locking member 6 and the item 7 to rise. When the operator stops applying the external force, the weight detected by the weight detection unit 12 becomes equal to the registered weight, and the locking member 6 and the item 7 immediately come to a stationary state. This control value includes, for example, acceleration.This balance control operation is performed by the balance control means 10b of the control unit 10.

[0038] On the other hand, when the operator presses the holding button 22, the control unit 10 of the main unit 2 receives the holding command and executes holding control to hold the lifting and lowering mechanism 16 in its current position. The holding control controls the motor unit 11 to maintain the lifting and lowering position of the locking member 6.

[0039] When an operator presses the up button 23 or down button 24, the control unit 10 of the main unit 2 receives this and controls the motor unit 11 to raise or lower the locking member 6. By continuously pressing the up button 23 or down button 24, the operator can continuously raise and lower the locking member 6 using the motor unit 11. Regardless of whether the main unit 2 is in the holding state or the balancing state, when an operator presses the up button 23 or down button 24, it will raise or lower, and when the operator releases the pressed up button 23 or down button 24, it returns to the holding state. This raising and lowering operation is performed by the speed control means 10c of the control unit 10.

[0040] The notification unit 18 is, for example, a light-emitting member or an acoustic member, and notifies the operator of information such as the operating status of the main unit 2 or the occurrence of an error, based on a command from the control unit 10.

[0041] The temperature detection unit 8 is provided near the exterior of the gears of the transmission in the motor unit 11, for example, to detect the temperature of the transmission and output the temperature value to the control unit 10.

[0042] Figure 5 is a flowchart of the operation performed by the control unit 10 of the electric lifting device 1 according to an embodiment of the present invention. When an operator turns on the power to the electric lifting device 1, the control unit 10 executes step S101 to hold the unwinding position of the link chain 4. The operator appropriately presses the up button 23 or down button 24 of the operation command unit 9 to bring the locking member 6 closer to the item 7 placed on a structure or the like, and locks it into the locking part of the item 7.

[0043] When the operator presses the lift button 23 on the operation command unit 9, the control unit 10 recognizes this as a lift command in step S102 and executes step S103, performing the hoisting operation of the link chain 4 to raise the item 7. When the operator has raised the item 7 to a position away from the structure (ground clearance), the operator presses the balance button 21. The control unit 10 then recognizes that the balance button 21 has been pressed in step S104 and proceeds to step S105.

[0044] In step S105, the control unit 10 receives the weight signal detected by the weight detection unit 12, stores it in the storage unit 10f, and proceeds to step S106. In step S106, the control unit 10 performs balance control on the item 7 based on this weight value. If the control unit 10 determines that any of the up button 23, down button 24, or hold button 22 has been pressed, it proceeds to Yes in step S107 or step S108, respectively, and releases the balance control to hold the position. If the balance button 21 is pressed again during balance control, the control unit 10 proceeds to Yes in step S109, receives the weight signal detected by the weight detection unit 12 at the moment the balance button 21 is pressed, stores it in the storage unit 10f and replaces it (step S105), and performs balance control on the item 7 based on the new registered weight value (step S106). If no operation buttons are pressed during balance control, the control unit 10 proceeds to step S109 to No and continues balance control.

[0045] Figure 6 is a flowchart of the control unit 10 of the electric lifting device 1 according to an embodiment of the present invention. Figure 6 shows the control flow related to the current command processing included in the control performed by the control unit 10 to the motor unit 11. This current command processing is performed as needed each time the control unit 10 executes a command to the motor unit 11, and is not necessarily performed in accordance with each step in Figure 5. This current command processing is performed as needed when the control unit 10 performs balance control in step S106 and lifting or lowering control in step S103.

[0046] In step S201, the control unit 10 calculates the current command value to the motor unit 11 based on the current state of the electric lifting device 1, obtains the calculated value, and proceeds to step S202. The current command value is defined, for example, as a positive value for the unwinding direction of the link chain 4 and a negative value for the winding direction of the link chain 4, and is transmitted from the control unit 10 to the motor driver of the motor unit 11. This calculation of the current command value is performed by the current command value calculation means 10d of the control unit 10.

[0047] In step S202, the control unit 10 determines whether to use the registered weight of the item 7 used for balance control to set the limited positive / negative predetermined values ​​(limit values). Whether or not to use this registered weight is determined in advance by the administrator of the electric lifting device 1 and stored in the memory unit 10f of the control unit 10.

[0048] If the control unit 10 determines in step S202 that it will not use the registered weight (No) to set the positive / negative predetermined values ​​(limit values), it proceeds to step S203. In step S203, the control unit 10 reads the positive predetermined value (positive limit value) for the unwinding direction of the link chain 4 and the negative predetermined value (negative limit value) for the winding direction of the link chain 4, and proceeds to step S204. Here, these two are defined as set A. In this case, from step S204 onward, the positive / negative predetermined values ​​(limit values) defined in set A become the limit range of the command value. In this embodiment, both the positive predetermined value (positive limit value) and the negative predetermined value (negative limit value) are used for control, but this is not limited to this; either one alone may be used. This is also true for set B, which uses a positive predetermined value (positive limit value) and a negative predetermined value (negative limit value) based on the registered weight, as described later.

[0049] The predetermined positive and negative values ​​set here are preferably determined by considering the characteristics of the motor in the motor unit 11, the characteristics of the transmission in the motor unit 11, etc. It is particularly preferable to determine them based on the temperature near the transmission of the motor unit 11. The temperature near the transmission of the motor unit 11 can be obtained by the temperature detection unit 8. If the characteristics of the transmission change significantly between the start of use and steady-state operation, it is also preferable to change the predetermined values ​​over time. In particular, if the location where the electric lifting device 1 is used is a cold region, the temperature difference of the transmission is large between the start of use and steady-state operation, and changing the predetermined values ​​is useful.

[0050] If the control unit 10 determines in step S202 to use the registered weight (Yes) to set the positive / negative predetermined values ​​(limit values), it proceeds to step S205. In step S206, the control unit 10 reads the positive predetermined value (positive limit value) for the unwinding direction of the link chain 4 and the negative predetermined value (negative limit value) for the winding direction of the link chain 4, and proceeds to step S204. Here, these two are defined as set B. In this case, from step S204 onward, the positive / negative predetermined values ​​(limit values) defined in set B become the limit range of the command value. These positive predetermined values ​​(positive limit values) and negative predetermined values ​​(negative limit values) are determined by calculation or other means based on the registered weight of the item 7 used for balance control. The predetermined positive / negative values ​​may be determined by calculation using a proportionality constant, or a range table may be created according to the registered weight value and read from it. The predetermined positive / negative values ​​set here are preferably determined by considering the characteristics of the motor in the motor unit 11, the characteristics of the transmission in the motor unit 11, and so on. It is particularly preferable to determine them based on the temperature near the transmission in the motor unit 11. The temperature near the transmission in the motor unit 11 can be obtained by the temperature detection unit 8. If the characteristics of the transmission change significantly between the start of use and steady-state operation, it is also preferable to change the predetermined values ​​over time. In particular, if the location where the electric lifting device 1 is used is a cold region, the temperature difference of the transmission is large between the start of use and steady-state operation, and changing the predetermined values ​​is useful.

[0051] If the control unit 10 determines in step S204 that the calculated value of the current command exceeds a predetermined positive value (Yes), it proceeds to step S207. In step S207, the control unit 10 controls the motor unit 11 using a predetermined positive value as the current command value, and proceeds to step S208. Alternatively, step S207 may be omitted, and the process may proceed directly to step S208. This command to determine the current command value is executed by the current command value determination means 10e of the control unit 10.

[0052] In step S208, the control unit 10 rotates the motor unit 11 in the reverse direction (the link chain 4 in the winding direction) and proceeds to step S209. The reverse rotation of the motor unit 11 may be performed for a predetermined time, or it may be performed by detecting the movement of the motor unit 11 (movement of the link chain 4) with the position detection unit 13. Alternatively, in step S207, the motor unit 11 may be controlled for a predetermined time using a positive predetermined value as the current command value, and then the process may proceed to step S208. In step S204, if the control unit 10 determines that the calculated value of the current command does not exceed a predetermined positive value (No), it proceeds to step S210.

[0053] If the control unit 10 determines in step S210 that the calculated value of the current command exceeds a predetermined negative value (Yes), it proceeds to step S211.

[0054] In step S211, the control unit 10 controls the motor unit 11 using a predetermined negative value as the current command value, and proceeds to step S212. Alternatively, step S211 may be omitted, and the process may proceed directly to step S212. This command to determine the current command value is executed by the current command value determination means 10e of the control unit 10.

[0055] In step S212, the control unit 10 rotates the motor unit 11 in the reverse direction (the link chain 4 is extended), and proceeds to step S209. The reverse rotation of the motor unit 11 may be performed for a predetermined time, or it may be performed by detecting the movement of the motor unit 11 (the movement of the link chain 4) with the position detection unit 13. Alternatively, in step S211, the motor unit 11 may be controlled for a predetermined time using a negative predetermined value as the current command value, and then the process may proceed to step S212.

[0056] If the control unit 10 determines in step S210 that the calculated value of the current command does not exceed a predetermined negative value (No), it proceeds to step S213. In step S213, the control unit 10 executes the current command value as the calculated value, and the current command processing is completed. This command to determine the current command value is executed by the current command value determination means 10e of the control unit 10.

[0057] In step S209, the control unit 10 controls the motor unit 11 to stop and maintain its position, then proceeds to step S214.

[0058] In step S214, the control unit 10 transmits a notification command to the notification unit 18. The notification unit 18 receives the notification command from the control unit 10 and notifies the worker by means of sound, light, or other means. At this time, the control unit 10 assumes that the electric lifting device 1 is in an abnormal state and maintains the link chain 4 in a held state until action is taken by the device manager or other relevant person.

[0059] Here, steps S207, S211, and S213 are performed by the current command value determination means 10e of the control unit 10.

[0060] Furthermore, in this configuration of the electric lifting device 1, even if the tangled portion of the link chain 4 hits the chain guides 19a, 19b, 19c, and 19d and jams, it does not affect the detected load detected by the weight detection unit. Therefore, it is clear that it is possible to distinguish between suspending a heavy object 7 and the link chain 4 being jammed by comparing the load and current.

[0061] Figures 7 to 9 are explanatory diagrams of the operation of the electric lifting device 1 according to an embodiment of the present invention, showing the state when an article 7 is moved from structure 32a to structure 32b. The operation of the electric lifting device 1 according to an embodiment of the present invention will be explained using Figures 7 to 9. The electric lifting device 1 is suspended from a movable block 30. The movable block 30 can move freely horizontally along the rail 31. Therefore, when an operator applies a horizontal external force to the article 7 suspended from the electric lifting device 1, the electric lifting device 1 can move along the rail 31.

[0062] Figure 7 is a schematic diagram of the intermediate steps in moving item 7 from structure 32a to structure 32b. The state in which item 7 is placed on structure 32a is not shown, but the worker can move the main unit 2 to the left in the drawing while balancing item 7 using the procedure described above to reach the state shown in Figure 7. The worker touches item 7 and applies an external force vertically downward, lowering item 7 to a height H1 from the floor surface of structure 32a. In this example, the link chain 4a is aligned between the chain bucket 17 and the lifting mechanism 16, so normal operation is performed.

[0063] Figure 8 is a schematic diagram showing the state when an operator touches the item 7 and applies a vertical downward force, lowering the item 7 to a height H2 from the floor surface of the structure 32a. In this example, entanglement occurs in the link chain 4a between the chain bucket 17 and the lifting mechanism 16. When the operator applies further vertical downward force to the item 7, the entanglement of the link chain 4a reaches the chain guides 19a, 19c, and 19d. This causes a rapid increase in the load on the motor unit 11 via the lifting mechanism 16, and the current command value to the motor unit 11 calculated by the control unit 10 increases to a predetermined value or higher. Therefore, the control unit 10 executes step S204, and then step S205. When the control unit 10 executes step S205, the lifting mechanism 16 rotates in the reverse direction, and the link chain 4 moves a predetermined distance Δh in the hoisting direction (see Figure 9). Then, the control unit 10 executes step S206, which turns on the light source of the notification unit 18, and the electric lifting device 1 stops while holding the link chain 4.

[0064] Figures 7 to 9 illustrate the entanglement of the link chain 4 when it is being unwound, but the execution process of the control unit 10 regarding the entanglement of the link chain 4 when it is being hoisted up is performed in the same manner as shown in Figure 6.

[0065] According to an embodiment of the electric lifting device of the present invention, damage to the electric lifting device due to entanglement of the link chain can be prevented.

[0066] Although the present invention has been described above based on preferred embodiments, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. [Industrial applicability]

[0067] As an example of its application, this invention can be used in electric lifting devices that are suspended from structures or mounted on mobile vehicles. [Explanation of Symbols]

[0068] 1: Electric lifting device 2: Main unit 3: Hanging hook 4: Link Chain 6: Locking member 7: Goods 8: Temperature detection unit 9: Operation command section 10: Control Unit 11: Motor section 12: Weight detection unit 13: Position detection unit 15: Rotating output shaft 16: Lifting mechanism 17: Chain Bucket 18: Hochi Department 19a, 19b, 19c, 19d: Chain guide 20: Operation Command Control Unit 21: Balance Button 22: Hold button 23: Up button 24: Down button 25: Operation command transmission / reception unit 30: Moving Block 31: Rail 32a, 32b: Structure

Claims

1. An electric lifting device comprising a lifting mechanism, a motor, and a control unit for raising and lowering a suspended article, The lifting mechanism raises and lowers the article by winding it up via a link chain through a locking member and then unwinding it. The motor unit rotates the lifting and lowering mechanism, The control unit, An electric lifting device that calculates a current command value for the motor unit, and if the calculated current command value exceeds a limit range defined by at least one predetermined positive / negative value, controls a command to reverse the rotation of the motor unit and then hold the link chain.

2. An electric lifting device for raising and lowering a suspended article, comprising a lifting operation unit, a motor unit, a weight detection unit, and a control unit, The lifting mechanism raises and lowers the article by winding it up via a link chain through a locking member and then unwinding it. The motor unit performs rotational drive of the lifting and lowering mechanism, The weight detection unit detects the weight applied to the lifting mechanism and transmits it to the control unit. The control unit, The motor unit can perform balance control by obtaining a weight value from the weight detection unit and balancing the force applied to the locking member by the lifting operation unit with the vertically downward force applied to the locking member, thereby bringing the locking member into a balanced state at any desired position. An electric lifting device that calculates a current command value for the motor unit, and if the calculated current command value exceeds a limit range defined by at least one of a predetermined positive / negative value determined from a weight value used for balance control, controls a command to reverse the rotation of the motor unit and then hold the link chain.

3. The electric lifting device according to claim 1 or 2, wherein if the calculated current command value exceeds the limit range, the control unit commands the motor unit to use the predetermined value exceeding the limit as the command value, and then controls the motor unit to rotate in the reverse direction.

4. The electric lifting device according to claim 1 or 2, wherein the predetermined value is determined by the temperature obtained from a temperature detection unit provided near the transmission of the motor unit.

5. A control method for an electric lifting device that raises and lowers a suspended article, comprising a lifting mechanism, a motor, and a control unit, The lifting mechanism raises and lowers the article by winding it up via a link chain through a locking member and then unwinding it. The motor unit performs rotational drive of the lifting and lowering mechanism, The control unit, The steps include: calculating the current command value for the motor unit, The steps include determining whether the calculated current command value exceeds a limit range defined by at least one of the predetermined upper and lower limits, If the calculated current command value exceeds the limit range, The steps include: rotating the motor section in the reverse direction, The steps include stopping and holding the rotation of the motor section, A control method for an electric lifting device.

6. A control method for an electric lifting device that lifts and lowers a suspended article, comprising a lifting operation unit, a motor unit, a weight detection unit, and a control unit, The lifting mechanism raises and lowers the article by winding it up via a link chain through a locking member and then unwinding it. The motor unit performs rotational drive of the lifting and lowering mechanism, The weight detection unit detects the weight applied to the lifting mechanism and transmits it to the control unit. The control unit, The motor unit can perform balance control by obtaining a weight value from the weight detection unit and balancing the force applied to the locking member by the lifting operation unit with the vertically downward force applied to the locking member, thereby bringing the locking member into a balanced state at any desired position. The steps include: calculating the current command value for the motor unit, The steps include determining whether the calculated current command value exceeds a limit range defined by at least one of the predetermined upper and lower limits, If the calculated current command value exceeds the limit range, The steps include: rotating the motor section in the reverse direction, The steps include stopping and holding the rotation of the motor section, A control method for an electric lifting device.

7. The control unit, If the calculated current command value exceeds the limit range, A control method for an electric lifting device according to claim 5 or 6, which involves performing the step of commanding the motor unit to the predetermined value that exceeds the limit as a command value, and then performing the step of rotating the motor unit in the reverse direction.

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