Upper and lower limit detection devices and methods for electric chain pulleys

Abstract

An upper and lower limit detection device and method for detecting the upper and lower limits of a cargo spreader in an electric chain trolley are provided, which can easily and quickly detect when the cargo spreader (hook) of the electric chain trolley reaches the lower limit without the need for a limit switch for lower limit detection. In an electric chain trolley (1) equipped with a motor (10), a friction clutch (11), an electromagnetic brake (12), a reduction gear mechanism (13), a lifting pulley (2), a lifting chain (3), and a cargo spreader (6), the upper limit detection limit switch (18) is used to detect when the cargo spreader (6) reaches the upper limit. The electric OLL (overload limiter) determines that the stop (8) abuts against the chain guide (4A), causing the friction clutch (11) to be dragged by the rotational force of the motor (10), and the power consumption of the motor (10) becomes above a specified value, thereby detecting when the lower limit is reached.

Description

Technical Field

[0001] This invention relates to an electric chain trolley for lifting (raising) and lowering (lowering) heavy objects (hereinafter referred to as "cargo"), and more particularly to an upper and lower limit detection device and method for an electric chain trolley that can reliably detect when the cargo lifting device (hook, etc.) suspending the cargo reaches its lower limit, unlike existing limit switches which are complex in structure and require adjustment after installation. Background Technology

[0002] Traditionally, electric chain trolleys are equipped with two limit switches: one for detecting when the load spreader mounted on the lifting chain reaches its upper limit, and another for detecting when it reaches its lower limit. When the load spreader reaches either the upper or lower limit, the power supply to the running motor is cut off, stopping the motor and preventing it from burning out. Additionally, a friction clutch is included in the drive force transmission path to prevent overloading of the mechanical system.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Published Patent No. 57-9356 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In electric chain hoists, there is a method where a limit switch for lower limit detection detects the arrival of the load-bearing device at the load-bearing end of the chain (used to prevent detachment) by detecting the end metal piece of the chain (installed on the unloaded side) at the unloaded end of the chain, thus stopping the motor. Typically, this lower limit detection limit switch is located near the chain guide on the main body, which guides the chain, and reliably detects the arrival of the end metal piece. However, the construction and arrangement of the components are constrained, leading to a large size issue. Furthermore, the limit switch consists of numerous components such as a limit rod, switch body, wires, and gaskets, resulting in a large number of parts and high cost. Additionally, after installing each component, it requires a complex operation to verify and adjust its functionality as a lower limit detection limit switch. In addition, in electric chain trolleys using friction clutches, although the friction clutch engages when the lifting hook or other lifting device reaches its lower limit to prevent overload of the mechanical system, the friction clutch continues to be dragged until operation is stopped, which increases its heat generation and has the potential to shorten the lifespan of the friction clutch.

[0008] The present invention was made in view of the above-mentioned problems, and its object is to provide an upper and lower limit detection device and method for an electric chain trolley: an electric OLL (overload limiter) is installed on the electric chain trolley, and in view of the situation that the power consumed by the motor increases when the lifting device such as the hook reaches the lower limit and the friction clutch is engaged, the electric OLL detects the power consumption and stops the motor.

[0009] Methods for solving problems

[0010] The upper and lower limit detection device for the cargo spreader of the electric chain trolley of the present invention is characterized in that the electric chain trolley includes an electric motor, a rotational force transmission mechanism that rotates through the electric motor, a rotational mechanism that rotates through the rotational force transmission mechanism, and a lifting chain wound around the rotational mechanism for lifting and lowering. The upper and lower limit detection device for the cargo spreader of the electric chain trolley includes an upper limit detection mechanism for detecting when the cargo spreader installed at the load-side end of the lifting chain reaches the upper limit, and a friction clutch (overload protection joint) is provided in the rotational force transmission mechanism. During lifting, the upper limit detection mechanism detects that the cargo spreader has reached the upper limit. On the other hand, during lowering, an electric OLL determines that the power consumption of the electric motor has become above a predetermined value due to the action of the friction clutch, thereby detecting that the cargo spreader has reached the lower limit.

[0011] Furthermore, the upper and lower limit detection device for the cargo lifting device of the electric chain trolley of the present invention is characterized in that, in the above-mentioned upper and lower limit detection device for the cargo lifting device of the electric chain trolley, the determination threshold of the electric type OLL when lowering the cargo lifting device is set to a value that is smaller than the determination threshold of the electric type OLL when raising the cargo lifting device and larger than the power consumption when the cargo lifting device is lowered without load.

[0012] Furthermore, the upper and lower limit detection device for the cargo lifting device of the electric chain trolley of the present invention is characterized in that, in the above-mentioned upper and lower limit detection device for the cargo lifting device of the electric chain trolley, the upper limit detection mechanism is a limit switch.

[0013] Furthermore, the upper and lower limit detection method for the cargo spreader of the electric chain trolley of the present invention is characterized in that the electric chain trolley includes an electric motor, a rotational force transmission mechanism that rotates through the electric motor, a rotational mechanism that rotates through the rotational force transmission mechanism, and a lifting chain wound around the rotational mechanism for lifting and lowering. The upper and lower limit detection method for the cargo spreader of the electric chain trolley includes the following steps: using an upper limit detection mechanism provided on the electric chain trolley, detecting that the cargo spreader installed at the load-side end of the lifting chain has reached the upper limit; and using an electric OLL to determine that the power consumption of the electric motor has become above a predetermined value due to the operation of the friction clutch (overload protection joint) provided on the rotational force transmission mechanism, thereby detecting that the cargo spreader has reached the lower limit.

[0014] Invention Effects

[0015] According to the present invention, the upper limit detection mechanism of the cargo spreader is used to detect when the cargo spreader reaches the upper limit. The electric OLL determines and detects that the friction clutch actuates when the cargo spreader reaches the lower limit, causing the motor to consume power from regenerative operation. Thus, the lower limit detection of the cargo spreader is performed. Therefore, the following beneficial effects can be obtained: in the lower limit detection of the cargo spreader, there is no need to use a lower limit detection mechanism with a large number of parts such as limit switches, and the lower limit of the cargo spreader can be detected simply by changing the software of the microcomputer of the electric chain trolley. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the electric chain trolley 1.

[0017] Figure 2 This is a diagram showing the approximate configuration of the limit switch 18 used for detecting the upper limit.

[0018] Figure 3 This is a graph showing the change in the power consumption of the electric motor relative to the load when the electric chain trolley 1 lifts goods.

[0019] Figure 4 This is a graph showing the change in power consumption of the electric motor relative to the load when the electric chain trolley 1 lowers the goods.

[0020] Figure 5 This is a diagram showing the changes in power consumption of the three-phase AC motor 10 from the moment it starts.

[0021] Figure 6 This is a diagram showing the changes in current consumption of the three-phase AC motor 10 from the moment it starts.

[0022] Figure 7 This is a diagram illustrating an example of the configuration of a control device for an electric chain pulley equipped with a three-phase AC motor 10.

[0023] Figure 8 This diagram illustrates an example of the configuration of a control device for an electric chain pulley equipped with a single-phase AC motor 50.

[0024] Figure 9 This is the motion control flowchart for the electric chain trolley 1.

[0025] Figure 10 This is a flowchart of the limit switch determination and processing.

[0026] Figure 11 This is the OLL decision processing flowchart. Detailed Implementation

[0027] The embodiments of the present invention will now be described in detail. Figure 1 This is a schematic diagram of the electric chain trolley 1 of the present invention. The electric chain trolley 1 includes an AC motor (here, a three-phase induction motor) 10 for lifting and lowering goods, a friction clutch (overload protection torque transmission mechanism) 11, an electromagnetic brake 27, a reduction gear mechanism 13, an SSR power circuit 121, a control unit 25, and other components and equipment. These components and equipment are adjusted to perform their respective functions and are appropriately arranged within the device housing 4. 2 is a lifting pulley (rotation mechanism) arranged within the device housing 4, on which a lifting chain 3 for lifting and lowering goods (not shown) is wound.

[0028] If the AC motor 10 is started and its rotor rotates in the forward direction (the direction of lifting the goods), its rotational force is transmitted to the rotating shaft of the lifting pulley 2 via the friction clutch 11 and the reduction gear mechanism 13 (that is, the friction clutch 11, the reduction gear mechanism 13, etc. are rotational force transmission mechanisms), and the lifting pulley 2 rotates in the forward direction. The lifting chain 3 moves in the direction of lifting the goods, that is, in the direction of the upward movement of the hook 6, which serves as a cargo lifting device, due to the rotation of the lifting pulley 2. Furthermore, here, the hook 6 is mounted on the lower end (load-side end) of the lifting chain 3 via the connecting member 5 in a manner that allows it to rotate freely on a plane orthogonal to the vertical direction of the lifting chain 3. A stop (end metal part) 8 is installed at the other end (unload-side end) of the lifting chain 3. The stop 8 prevents the lifting chain 3 from falling off the body by engaging with the lower surface of the chain guide hole 4b of the chain guide 4A provided at the bottom of the device housing 4 when the chain is excessively lowered. 18 is a limit switch for detecting when hook 6 has reached its upper limit (hereinafter referred to as "upper limit switch").

[0029] Furthermore, this section describes an example of using a contact-type upper limit switch 18 to detect when the hook (cargo spreader) 6 reaches its upper limit. However, the upper limit detection mechanism for detecting when the hook 6 reaches its upper limit is not limited to this. Various sensors that detect when the hook 6 reaches its upper limit in a non-contact manner, such as magnetic sensors, can also be used.

[0030] Furthermore, the padding rubber 5a attached to the upper surface of the aforementioned connecting component 5 also functions as a buffer component to cushion the impact between the hook 6 and the lower surface of the surrounding portion of the chain guide hole 4a located at the bottom of the device housing 4 when the heavy chain 3 is excessively lifted. It also functions to push up the lower end 18d of the lever portion 18a of the upper limit switch 18. That is, as... Figure 2 As shown, the front end of the rod 18a of the upper limit switch 18 is bent into a U-shape. The lower end 18d of this bent portion abuts against the padding rubber 5a of the connecting member 5 and is pushed up. As a result, the drive protrusion 18c of the limit switch body 18b is pushed up, and the limit switch body 18b becomes closed. In addition, a bucket 7 is installed below the device housing 4 of the electric chain trolley 1 to accommodate the unloaded side of the lifting chain 3 (the side opposite to the side where the hook 6 is installed). That is, when the hook 6 rises, the lifting chain 3 is continuously accommodated in the bucket 7, and when the hook 6 descends, the lifting chain 3 is continuously released from the bucket 7.

[0031] The electric chain trolley 1 includes an operation unit 19 for operating the device. This operation unit 19 includes a lift button switch 19a, a lower button switch 19b, and an emergency stop button switch 19c. Pressing the lift button switch 19a sends a lift signal SU to the control unit 25, and pressing the lower button switch 19b sends a lower signal SD to the control unit 25. When lifting goods (not shown) using the electric chain trolley 1, the goods are first attached to the hook 6, which serves as a lifting device, and then the lift button switch 19a on the operation unit 19 is pressed. This sends a lift signal SU from the operation unit 19 to the control unit 25. Upon receiving the lift signal SU, the control unit 25 outputs a control signal S2 to the SSR (solid-state relay) operating circuit 121, supplying three-phase AC power in the phase sequence required to rotate the rotor of the AC motor 10. As a result, the AC motor 10 rotates forward, and its rotational force is transmitted to the lifting pulley 2 through the friction clutch 11 and the reduction gear mechanism 13. The lifting pulley 2 rotates in the direction that causes the hook 6 to rise.

[0032] Furthermore, if the hook 6 rises to its upper limit, the rubber pad 5a on the upper surface of the connecting component 5 abuts against the lower end 18d of the rod 18a, pushing it upward and pressing the drive protrusion 18c upward. If this causes the switch body 18b to activate (normally closed contact opens), an upper limit detection signal S1 is output to the control unit 25, notifying the hook 6 that it has reached its upper limit. Upon receiving the upper limit detection signal S1, the control unit 25 outputs a control signal S2 to the SSR power circuit 121, cutting off the power supplied to the AC motor 10, causing the AC motor 10 to stop, and cutting off the current supplied to the electromagnetic brake 27, thus mechanically restricting the rotation of the rotor shaft of the AC motor 10.

[0033] Alternatively, the limit switch used in the detection of the upper limit of the hook 6 of the electric chain trolley 1 as described above can be used as a limit switch to detect when the hook 6 reaches the lower limit when lowering the goods. However, as mentioned above, the limit switch has a large number of parts, and its installation and adjustment are complicated. Therefore, the limit switch is only used for detecting the upper limit of the hook 6. In detecting the lower limit of the hook 6, the determination is made by an electric OLL.

[0034] Figure 3 , Figure 4 These are graphs showing the change in power consumption of the electric motor relative to the load of the electric chain trolley 1. Figure 3 This indicates the status of the goods being picked up. Figure 4 This indicates the situation of goods being released. In the case of goods being retrieved, such as... Figure 3 As shown, the power consumption of the AC motor increases proportionally with the increase of the load from a predetermined value (power consumption when lifting without load) S1, but reaches its peak at point A when the friction clutch 11 actuates. In contrast, when lowering goods, as... Figure 4 As shown, the power consumption of the AC motor decreases inversely with the increase of load from the specified value (power consumption when no load is applied) S2. The load value becomes zero at the specified value S3. After that, the AC motor 10 acts as a generator to produce regenerative power.

[0035] As described above, when the electric chain trolley 1 is lowering goods, the greater the weight of the goods, the more negatively the power consumption of the AC motor 10 increases (regenerative power increases). Therefore, the electric OLL does not operate according to the weight of the goods. Thus, when the hook 6 reaches its lower limit, or when the lifting chain 3 gets stuck in the chain bucket 7 and collides with the chain guide 4A, causing the friction clutch 11 to engage, the power consumption of the AC motor 10 becomes positive and increases. The electric OLL detects this situation, indicating that the hook 6 has reached its lower limit (cannot be lowered further), and stops the AC motor 10. The determination setting for the electric OLL during lowering is different from that during lifting. That is, as explained below, the determination time and threshold for lowering are different. Figure 4 In this context, the OLL decision threshold M1 is set to be lower than the value indicated by the upward movement. Figure 3 The value of the OLL judgment threshold M2 is greater than the power consumption S2 during no-load lowering. The reason for setting the value of the OLL judgment threshold M1 in this way is that: if the power consumption during normal lowering operation is higher than the power consumption S2 during no-load lowering, which has the highest power consumption, it means that the hook 6 has reached the lower limit or the lifting chain 3 is stuck in the chain bucket 7 and collides with the chain guide 4A, etc. (that is, it cannot be lowered further). Therefore, the AC motor 10 is stopped early without waiting for the value to reach the value of the OLL judgment threshold M2.

[0036] Figure 5 , Figure 6 It means Figure 1 The diagram shows the changes in power consumption and current of the AC motor 10 of the electric chain trolley 1 from the moment it starts and lowers. Here, the AC motor 10 is a three-phase 200V motor. Figure 5 The diagram shows the measurement of power consumption of the AC motor 10 when it rotates in the direction of unloading goods and reaches its lower limit at point A, causing the friction clutch 11 to engage. Figure 6 The diagram shows the measurement of the current (actual value). Figure 5 In the middle, at point A (when hook 6 reaches its lower limit), friction clutch 11 engages, and AC motor 10 switches from self-regenerating operation to power (electricity consumption) operation. It is also known that... Figure 6 In the middle, at point B (at the intersection with...) Figure 5 At the same time point as point A (when hook 6 reaches its lower limit), even if friction clutch 11 is activated, the current will not be as... Figure 5 It changes like the changes in electricity.

[0037] Figure 7This diagram illustrates an example of the configuration of a control device for an electric chain trolley equipped with a three-phase AC motor. Here, an example is described using a three-phase AC motor (here, a three-phase induction motor) 10 for lifting and lowering goods. This electric chain trolley control device includes a control board 120, on which five contactless switching elements 121-1 to 121-5 constituting an SSR operating circuit (three-phase contactless assembly) 121 are mounted. Here, contactless switching elements 121-1 to 121-3 are used to rotate the three-phase AC motor 10 in the forward direction, i.e., in the direction of lifting goods (raising the goods), while contactless switching elements 121-4, 121-2, and 121-5 are used to rotate the three-phase AC motor 10 in the reverse direction, i.e., in the direction of lowering goods (lowering the goods).

[0038] In addition, the control board 120 is provided with three supply terminals Rt, St, and Tt for supplying three-phase AC power from the three-phase AC power supply 100 to its input side, and three output terminals Ut, Vt, and Wt for outputting three-phase AC power controlled by the control board 120 to the three-phase AC motor 10. Moreover, a contactless switch element 121-1 is arranged between the supply terminal Rt and the output terminal Ut via patterned wiring 122-1, a contactless switch element 121-2 is arranged between the supply terminal St and the output terminal Vt via patterned wiring 122-2, and a contactless switch element 121-3 is arranged between the supply terminal Tt and the output terminal Wt via patterned wiring 122-3, forming three power lines for supplying three-phase AC current to the three-phase AC motor 110 to generate a rotating magnetic field that causes its rotor (not shown) to rotate forward.

[0039] Furthermore, a contactless switching element 121-4 is arranged between the supply terminal Rt and the output terminal Wt via patterned wiring 122-4, and a contactless switching element 121-5 is arranged between the supply terminal Tt and the output terminal Ut via patterned wiring 122-5. Using the contactless switching element 121-4 and patterned wiring 122-4, the contactless switching element 121-5 and patterned wiring 122-5, and the aforementioned contactless switching element 121-2 and patterned wiring 122-2, three energizing lines are respectively formed to supply three-phase alternating current to the three-phase AC motor 10, generating a rotating magnetic field for reversing its rotor.

[0040] In addition, a current sensor 128S for detecting the S-phase current supplied to the V-phase winding of the three-phase AC motor 10 is disposed between the supply terminal St and the contactless switching element 121-2 via patterned wiring 122-2. A current sensor 128T for detecting the T-phase current supplied to the W-phase winding or U-phase winding of the three-phase AC motor 10 is disposed between the supply terminal Tt and the contactless switching element 121-3 via patterned wiring 122-3.

[0041] Furthermore, a control unit 25, including a microcomputer and various circuits, is mounted on the aforementioned control board 120. The phase-to-phase AC voltage (phase-to-phase voltage) input to the control unit 25, which is fed to the supply terminals St and Tt, is input via patterned wirings 122-6 and 122-7. Additionally, the detection current values ​​IS and IT detected by current sensors 128S and 128T are also input to the control unit 25. The control unit 25 calculates power consumption, power smoothing, etc., based on the input voltage and current values, and further performs an OLL determination based on power consumption. Furthermore, leads 111-1 and 111-2, which are connected to the windings of the U-phase and V-phase of the stator of the three-phase AC motor 10, are connected to the output terminals Ut and Vt of the control board 120. Moreover, lead 111-3, which is connected to the winding of the W-phase of the stator of the three-phase AC motor 10, is connected to the output terminal Wt of the control board 120 via a full-wave rectifier circuit 26.

[0042] Additionally, 27 is an electromagnetic brake, whose excitation coil 27a is connected to the output terminal of the full-wave rectifier circuit 26. If the AC current from the output terminal Wt of the control board 120 is converted into DC by the full-wave rectifier circuit 26 and flows as the brake current through the excitation coil 27a, the electromagnetic brake 27 is released, and the rotor of the three-phase AC motor 10 becomes unrestricted.

[0043] 19 is the operating section of the control device for this electric chain trolley, which includes an emergency stop button switch 19c, a lift button switch 19a, and a lower button switch 19b. If, for example, the lift button switch 19a of the operating section 19 is pressed while the three-phase AC power supply (commercial three-phase power supply) 100 is connected via the supply terminals Rt, St, and Tt of the control board 120, a lift signal SU is output to the control unit 25. The control unit 25 processes this signal and controls the conduction of the contactless switching elements 121-1, 121-2, and 121-3 of the SSR operating circuit 121, supplying a three-phase current to the stator windings of the three-phase AC motor 10 to generate a rotating magnetic field that causes its rotor to rotate in the direction of lifting the goods. Simultaneously, a brake current is supplied to the excitation coil 27a of the electromagnetic brake 27 via the full-wave rectifier circuit 26, releasing the electromagnetic brake 27. As a result, the rotor of the three-phase AC motor 10 rotates in the direction of lifting the goods, thus lifting the goods (raising them upwards).

[0044] In addition, when the goods reach the designated position, by stopping the pressing of the lifting button switch 19a, the input of the lifting signal SU to the control unit 25 is stopped. Through the processing of the control unit 25, the contactless switch elements 121-1, 121-2, and 121-3 are disconnected (turned off), the power supply to the three-phase AC motor 10 is stopped, and the input of brake current to the excitation coil 27a of the electromagnetic brake 27 is stopped. The electromagnetic brake 27 is mechanically activated, and the rotor of the three-phase AC motor 10 stops (is restricted).

[0045] If the lowering button switch 19b of the operation unit 19 is pressed, a lowering signal SD is output to the control unit 25. The control unit 25 processes this signal and controls the conduction of the contactless switching elements 121-4, 121-2, and 121-5 of the three-phase contactless assembly 121, supplying a three-phase current to the three-phase AC motor 10 to generate a rotating magnetic field that causes its rotor to rotate in the direction of lowering the goods. Simultaneously, a brake current is supplied to the excitation coil 27a of the electromagnetic brake 27 via the full-wave rectifier circuit 26, releasing the electromagnetic brake 27. As a result, the rotor of the three-phase AC motor 10 rotates, lowering the goods (causing them to descend).

[0046] After the goods arrive at the designated location, by stopping the pressing of the lowering push-button switch 19b, the input of the lowering signal SD to the control unit 25 is stopped. Through the processing of the control unit 25, the contactless switching elements 121-4, 121-2, and 121-5 are disconnected, stopping the power supply to the three-phase AC motor 10. At the same time, the input of brake current to the excitation coil 27a of the electromagnetic brake 27 is stopped, the electromagnetic brake 27 is mechanically activated, and the rotor of the three-phase AC motor 10 stops (is restricted).

[0047] Figure 8 This diagram illustrates an example of the configuration of a control device for an electric chain trolley equipped with a single-phase AC motor (in this case, a single-phase induction motor) 50 for loading and unloading goods. Figure 8 In the middle, the control board 120 itself is with Figure 7 The control board 120 of the control device for the electric chain trolley shown has the same structure. That is, a contactless switch element 121-1 is arranged between the supply terminal Rt and the output terminal Ut via patterned wiring 122-1, a contactless switch element 121-2 is arranged between the supply terminal St and the output terminal Vt via patterned wiring 122-2, a contactless switch element 121-3 is arranged between the supply terminal Tt and the output terminal Wt via patterned wiring 122-3, a contact switch element 121-4 is arranged between the supply terminal Rt and the output terminal Wt via patterned wiring 122-4, and a contactless switch element 121-5 is arranged between the supply terminal Tt and the output terminal Ut via patterned wiring 122-5.

[0048] exist Figure 8 In this configuration, two connecting lines (external wiring) 61 and 62 are added to the input side of the control board 120, which is configured with supply terminals Rt, St, and Tt. The first connecting line 61 connects to supply terminals Rt and St, electrically integrating them (short-circuiting), and uses one end as a single-phase AC power supply terminal SP1 connected to one terminal of the single-phase AC power supply (commercial single-phase power supply) 200. The second connecting line 62 is electrically connected to supply terminal Tt, with one end serving as a single-phase supply terminal SP2 connected to the other terminal of the single-phase AC power supply (commercial single-phase power supply) 200, and the other end connected to the phase-advancing capacitor 65.

[0049] A single-phase AC motor 50 is configured on the output side of the control board 120, which is configured with output terminals Ut, Vt, and Wt. This single-phase AC motor 50 has a main winding 51 and an auxiliary winding 52. One end U of the main winding 51 is connected to the output terminal Ut of the control board 120 via lead 66-1, and the other end V of the main winding 51 is connected to the midpoint of the full-wave rectifier circuit 26 via lead 66-2. The output terminal of the full-wave rectifier circuit 26 is connected to one end of the excitation coil 27a of the electromagnetic brake 27, and the other end of the excitation coil 27a is connected to the output terminal Wt of the control board 120 via the full-wave rectifier circuit 26. One end Y of the auxiliary winding 52 is connected to the output terminal Vt of the control board 120 via lead 66-3, and the other end X of the auxiliary winding 52 is connected to one end of the leading capacitor 65 via lead 66-4.

[0050] exist Figure 8 The control device for the electric chain trolley shown also includes... Figure 7 Similarly, it includes an operation unit 19 and a control unit 25, including an emergency stop button switch 19c, a lift button switch 19a, and a lower button switch 19b. Furthermore, when a single-phase AC power supply 200 is connected between single-phase AC power supply terminals SP1 and SP2, and the single-phase AC power supply 200 is on, pressing, for example, the lift button switch 19a on the operation unit 19 outputs a lift signal SU to the control unit 25; pressing the lower button switch 19b outputs a lower signal SD to the control unit 25. Additionally, the contactless switching elements 121-1, 121-2, 121-3, 121-4, and 121-5 are switched on and off via control signals from the control unit 25, causing the rotor of the single-phase AC motor to rotate in the direction of lifting or lowering the goods. These points are equivalent to... Figure 7 The control device used in the electric chain trolley shown is the same.

[0051] Next, use Figures 9-11 This describes an example of the control unit 25 of the electric chain trolley 1. Figure 9This is a flowchart of the motion control of the electric chain trolley 1 based on the control unit 25.

[0052] As shown in the figure, the control unit 25 first measures the voltage and current values ​​(steps 1-1 and 1-2). Then, it calculates the power value (electrical power value) based on the measured voltage and current values ​​(steps 1-3).

[0053] Next, two smoothed power values ​​(smoothed power values) are calculated based on the power value (steps 1-4). Here, the smoothed power value is the power value that smooths the power value that fluctuates up and down at a predetermined period when lifting and lowering the lifting chain 3. One of the two smoothed power values ​​is the smoothed power value X1 that smooths the AC power of the three-phase AC power supply 100. The other is the smoothed power value X2 that smooths the up and down fluctuation of the power value caused by the load change due to the polygonal shape of the lifting pulley 2 during lifting, with the period of its change. The smoothed power value X1 is used when lowering without applying a load from the lifting chain 3, and the smoothed power value X2 is used when lifting with a load from the lifting chain 3. That is, the smoothed power value X1 is the power value smoothed with half a cycle of the AC cycle of the three-phase AC power supply 100 (1 / 120 second at 60Hz), and the smoothed power value X2 is the smoothed power value based on the changing period of the lifting pulley 2.

[0054] Next, proceed to steps 1-5 to perform limit switch determination processing. The limit switch determination processing determines whether the lifting chain 3 has been lifted, causing the padding rubber 5a of the connecting component 5 to abut against the upper limit switch 18, and performs this processing.

[0055] Figure 10 This is a diagram illustrating the processing flow of the limit switch determination process described above. As shown in the diagram, the control unit 25 first determines whether the current operating mode is lifting or lowering. If it is lowering, since the connecting part 5 will not come into contact with the upper limit switch 18, the limit switch determination process is skipped (step 2-1, "No").

[0056] On the other hand, while the movement is in progress, the process moves from "Yes" in step 2-1 to step 2-2 to determine whether the upper limit switch 18 is already engaged. Furthermore, if it is determined that the upper limit switch 18 is already engaged, the process moves to step 2-3, where an error "upper limit" is stored (set) in the control unit 25. Simultaneously, the control unit 25 cuts off the power supply to the AC motor 10. This cutoff is reset, for example, by pressing the lowering button switch 19b or the emergency stop button switch 19c of the operation unit 19. Additionally, if it is determined in step 2-2 that the upper limit switch 18 is not engaged ("No" in step 2-2), step 2-3 is skipped, and the process ends.

[0057] Next, return Figure 9 The control unit 25 performs OLL determination processing (steps 1-6). When the lifting chain 3 is being lifted or lowered, if a load exceeding a specified value is applied to the AC motor 10, the OLL determination processing detects this situation and performs processing such as stopping the AC motor 10.

[0058] Figure 11 This is a diagram illustrating the processing flow of the aforementioned OLL determination process. As shown in the diagram, in step 3-1, the control unit 25 first determines whether the current operating mode is "lifting", "lowering", or "other (stopped)". Moreover, when the condition in step 3-1 is "other", since neither lifting nor lowering is being performed, there is no need to perform the OLL determination process, so this OLL determination process is skipped.

[0059] Next, if the current operating mode is "lifting" in step 3-1, proceed to step 3-2 to determine the... Figure 9 The smoothed power value X2 calculated in steps 1-4 is checked against the predetermined judgment threshold M2. If the smoothed power value X2 exceeds the predetermined judgment threshold M2, an overload is detected ("Yes" in step 3-2), and an error "OLL" is stored in the control unit 25 (an error flag is set). Simultaneously, the control unit 25 cuts off the power supply to the AC motor 10 (step 3-3). For example, an overload occurs when the hook 6 is suspending a load exceeding its rated load (see [reference]). Figure 3 On the other hand, if the smoothed power value X2 does not exceed the specified judgment threshold M2 in step 3-2, it is determined that it is not an overload (No in step 3-2), step 3-3 is skipped, and the process ends.

[0060] Next, if the current operating mode is "lowering" in step 3-1, proceed to step 3-4 to determine the... Figure 9 The smoothing power value X1 calculated in steps 1-4 shown above is checked against the specified OLL judgment threshold M1. If it exceeds this threshold, it is determined to be at the lower limit (cannot be lowered) ("Yes" in steps 3-4), and stored as an error "lower limit" in the control unit 25 (error flag set). Simultaneously, the control unit 25 cuts off the power supply to the AC motor 10 (step 3-5). As described above, for example, when the stop member 8 engages with the lower surface of the chain guide hole 4b of the chain guide member 4A located at the bottom of the device housing 4 due to excessive chain lowering, or when the lifting chain 3 is stuck in the chain bucket 7 and collides with the chain guide member 4A, causing the friction clutch 11 to actuate, an overload occurs (see reference). Figure 5Furthermore, the OLL determination threshold M1 during the lowering phase is set to be lower than the OLL determination threshold M2 during the raising phase, and greater than the power consumption S2 during the no-load lowering phase, as described above. On the other hand, in step 3-4, if the smoothed power value X1 does not exceed the predetermined OLL determination threshold M1, it is determined that it is not an overload (No in step 3-4), step 3-5 is skipped, and the process ends.

[0061] Next, move to Figure 9 Steps 1-7, as shown, perform motor control processing corresponding to the pressed state and error state of the button switches. That is, based on the error flag state and the signals from the various button switches 19a-19c of the operation unit 19, lifting and lowering control are executed. If no error flag is set, normal operation can continue. If an error flag is set, operation can be controlled according to the type of error flag. Error flags are broadly categorized into resettable and non-resettable operations. For example, if the error "OLL" is set, operation on the lifting button switch 19a is not accepted (non-resettable), and the error is cleared (reset) by pressing the emergency stop button switch 19c or the lowering button switch 19b. Similarly, if the error "lower limit" is set, operation on the lowering button switch 19b is not accepted (non-resettable), and the error is cleared (reset) by pressing the emergency stop button switch 19c or the lifting button switch 19a.

[0062] Then, through the above motor control process, if operation continues, proceed to step 1-1 and continue operating; if operation stops, stop operating (step 1-8).

[0063] As explained above, the upper and lower limit detection device or method for the hook (cargo lifting device) 6 of the electric chain trolley 1 according to this embodiment detects that the hook 6 has reached the upper limit when it is lifted, using the upper limit detection limit switch (upper limit detection mechanism) 18. On the other hand, when it is lowered, the electric OLL determines that the power consumption of the AC motor 10 has become a predetermined value or higher due to the action of the friction clutch 11, thereby detecting that the hook 6 has reached the lower limit. Therefore, in the detection of the lower limit of the hook 6, it is not necessary to use a lower limit detection mechanism with a large number of parts such as limit switches, and the lower limit of the hook 6 can be detected simply by changing the software of the microcomputer provided by the electric chain trolley 1.

[0064] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the technical concept described in the claims, specification and drawings.

[0065] Explanation of reference numerals in the attached figures

[0066] 1 Electric chain pulley

[0067] 2 lifting pulleys (rotating mechanism)

[0068] 3 lifting chains (traction mechanism)

[0069] 4. Device casing

[0070] 4A chain guide

[0071] 5 connecting parts

[0072] 6. Lifting hooks (cargo lifting tools)

[0073] 7 chain buckets

[0074] 8 stop parts

[0075] 10. Three-phase AC motors (electric motors, AC motors, three-phase induction motors)

[0076] 11. Friction clutch (clutch with overload protection mechanism)

[0077] 13. Reduction Gear Mechanism

[0078] 18 Limit switch for reaching the upper limit (upper limit detection mechanism, upper limit switch) 19 Operation section

[0079] 25 Control Department

[0080] 26 Full-Wave Rectifier Circuit

[0081] 27 Electromagnetic brake

[0082] 27a excitation coil

[0083] 50 Single-phase AC motor (electric motor, single-phase induction motor)

[0084] 100V three-phase AC power supply (commercial three-phase power supply)

[0085] 120 control board

[0086] 121SSR Power Circuit (Three-phase contactless assembly)

[0087] 121-1~121-5 Contactless Switching Elements

[0088] 200V single-phase AC power supply (commercial single-phase power supply)

[0089] M1 OLL decision threshold (during deployment)

[0090] M2 OLL decision threshold (when raised)

Claims

1. A device for detecting the upper and lower limits of a cargo lifting device for an electric chain trolley, characterized in that, The electric chain trolley includes an electric motor, a rotational force transmission mechanism that rotates via the electric motor, a rotational mechanism that rotates via the rotational force transmission mechanism, and a lifting chain wound around the rotational mechanism for lifting and lowering goods, thereby lifting or lowering goods engaged with a cargo spreader installed at the load-side end of the lifting chain. The upper and lower limit detection device of the cargo spreader of the electric chain trolley includes an upper limit detection mechanism for detecting when the cargo spreader reaches its upper limit, and a friction clutch is included in the rotational force transmission mechanism. During the lifting process, the upper limit detection mechanism detects that the cargo spreader has reached its upper limit. Conversely, during the lowering process, an electric OLL determines that the power consumption of the motor has exceeded a predetermined value due to the operation of the friction clutch, thereby detecting that the cargo spreader has reached its lower limit. The threshold for determining the electric OLL when lowering the cargo spreader is set to a value that is smaller than the threshold for determining the electric OLL when raising the cargo spreader and larger than the power consumption when the cargo spreader is lowered without load.

2. The upper and lower limit detection device for the cargo lifting device of the electric chain trolley as described in claim 1, characterized in that, The upper limit detection mechanism is a limit switch.

3. A method for detecting the upper and lower limits of the cargo lifting device of an electric chain trolley, characterized in that, Prepare an electric chain trolley, which includes an electric motor, a rotational force transmission mechanism that rotates via the electric motor, a rotational mechanism that rotates via the rotational force transmission mechanism, and a lifting chain wound around the rotational mechanism for lifting and lowering goods, so as to lift or lower goods that are engaged with a cargo spreader installed at the load-side end of the lifting chain. The method for detecting the upper and lower limits of the cargo spreading device of the electric chain trolley includes the following steps: The upper limit detection mechanism installed on the electric chain trolley is used to detect when the cargo spreader reaches its upper limit. as well as The electric OLL (Optical Linear Lift) determines that the power consumption of the motor has exceeded a predetermined value due to the action of the friction clutch in the rotational force transmission mechanism, thereby detecting that the cargo spreader has reached its lower limit. The threshold for determining the electric OLL when lowering the cargo spreader is set to a value that is smaller than the threshold for determining the electric OLL when raising the cargo spreader and larger than the power consumption when the cargo spreader is lowered without load.

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