Control device for hoisting machine and hoisting machine

Abstract

This control device 10 for a hoisting machine comprises: a main circuit 31 to which a power supply 102 and an electric motor 1 are connected, an operation circuit 32 to which an operation input device 5 is connected, a power-on / off electromagnetic contactor 21 having a main contact 210 provided in the main circuit 31, and a coil 212 and a sub-contact 211 provided in the operation circuit 32; and an overwinding prevention device 22 which is connected to the operation circuit 32 and is configured to stop energization to the electric motor 1 when the load hook reaches an upper limit position or a lower limit position. When the ON-operation switch 50 is operated, the main contact 210 provided in the main circuit 31 and the sub-contact 211 provided in the operation circuit 32 are closed, and the operation circuit 32 forms a self-holding circuit. When the overwinding prevention device 22 is operated during driving of the electric motor 1, the self-holding circuit formed by the operation circuit 32 is released, the main contact 210 and the sub-contact 211 are opened, and energization to the electric motor 1 is stopped.

Description

Hoist control device and hoist

[0001] The present invention relates to a control device for a hoist and a hoist.

[0002] Conventionally, hoists using three-phase induction motors have been known. If such hoists are mistakenly connected to a power source in the wrong phase during installation, the direction of rotation of the motor will be reversed relative to the desired direction, resulting in reversed hoisting and lowering operations.

[0003] To prevent these problems, Patent Document 1 discloses a hoist equipped with a negative-phase reversing relay. This negative-phase reversing relay detects a negative-phase connection and supplies power to the motor as is when the power supply and the motor are connected in positive phase, and supplies phase-reversed power to the motor when the power supply and the motor are connected in negative phase. This allows the motor to operate in the same way as when the power supply is connected in positive phase, even when the power supply and the motor are connected in negative phase. Furthermore, the hoist disclosed in Patent Document 1 has a device that performs hoisting operations during hoisting and lowering operations during lowering, even if the contacts of the electromagnetic switch on the power supply side are welded during a negative-phase connection, thereby improving safety during a negative-phase connection.

[0004] Japanese Patent Application Publication No. 9-20495

[0005] However, the negative-phase reversing relay has a complex structure and becomes unnecessary after a hoisting machine that is connected to a power supply in the negative phase is reconnected to the positive phase, or when the hoisting machine is connected in the positive phase during installation.

[0006] The present invention aims to achieve both safety and functionality of a hoisting machine without using a negative-phase reversing relay.

[0007] A control device for a hoisting machine in one embodiment includes a first circuit connecting a power source and an electric motor, a second circuit connected to an operation input device that receives operations to instruct operation of the electric motor, a first contact provided in the first circuit and opening and closing to connect or disconnect the power source and the electric motor, a coil provided in the second circuit, and a second contact provided in the second circuit and opening and closing to connect or disconnect the operation input device to the second circuit, the power source being an electromagnetic contactor that puts the electric motor into a drivable state in response to operation of a first switch provided in the operation input device, and an overwinding prevention device connected to the second circuit and cutting off current to the electric motor when a load hook that hooks a load reaches an upper limit position or a lower limit position due to operation of the electric motor. When the first switch is operated and the coil is energized, the first contact and the second contact close, and the second circuit forms a self-holding circuit that maintains the energized state. When the overwinding prevention device is activated while the motor is running, the self-holding circuit formed by the second circuit is released, the first contact and the second contact open, and power to the motor is stopped.

[0008] In one embodiment, the hoisting machine includes an electric motor driven by power supplied from a power source, an operation input device that receives an operation commanding operation of the electric motor, and a control device that controls driving of the electric motor in accordance with the operation received by the operation input device. The control device includes a first circuit connecting the power source and the electric motor, a second circuit to which the operation input device is connected, a first contact provided in the first circuit and opening and closing to connect or disconnect the power source and the electric motor, a coil provided in the second circuit, and a second contact provided in the second circuit and opening and closing to connect or disconnect the operation input device to the second circuit, and a power on / off electromagnetic contactor that puts the electric motor into a drivable state in accordance with operation of a first switch provided in the operation input device, and an overwinding prevention device connected to the second circuit and that stops power supply to the electric motor when a load hook that hooks a load by driving the electric motor reaches an upper limit position or a lower limit position. When the first switch is operated to energize the coil, the first and second contacts close, and the second circuit forms a self-holding circuit that maintains the energized state. When the overwinding prevention device operates while the motor is running, the self-holding circuit formed by the second circuit is released, the first and second contacts open, and the supply of electricity to the motor is stopped.

[0009] According to the present invention, it is possible to achieve both safety and functionality of the hoist.

[0010] It is an appearance side view of the hoisting machine of the embodiment. It is a front appearance view of the hoisting machine. It is a connection diagram showing the control configuration of the hoisting machine. It is a connection diagram showing the control configuration of the hoisting machine of a modified example.

[0011] Hereinafter, a hoist according to an embodiment of the present invention will be described in detail with reference to the drawings. In the following, an electric chain hoist will be used as an example of the hoist, but the hoist is not limited to an electric chain hoist.

[0012] <Overall Configuration> Fig. 1 is an external side view of a hoist 100 according to an embodiment, and Fig. 2 is an external front view of the hoist 100 according to an embodiment. Fig. 3 is a connection diagram showing the control configuration of the hoist 100 according to an embodiment.

[0013] The hoist 100 comprises a hoist main body 101, an electric motor 1, a reducer 2, an electromagnetic brake 3, an upper hoisting device 4, an operation input device 5, a chain bucket 6, a sprocket 7, a load hook 8, a chain 9, and a control device 10.

[0014] The hoist body 101 is rectangular parallelepiped and includes a central housing 101a, a motor housing 101b, and a reducer housing 101c. The central housing 101a is located in the longitudinal center of the hoist body 101. The motor housing 101b is located on one side of the central housing 101a in the longitudinal direction of the hoist body 101. The reducer housing 101c is located on the other side of the central housing 101a in the longitudinal direction of the hoist body 101.

[0015] An upper hoisting device 4 is attached to a surface 101d on one side of the central housing 101a. The hoisting machine 100 is used while suspended by this upper hoisting device 4. A chain bucket 6 is attached to a surface 101e on the other side of the central housing 101a. The chain bucket 6 is a chain accommodating device that accommodates one end of the chain 9. In the following description, the surface 101d side of the central housing 101a may be referred to as the upper side, and the surface 101e side may be referred to as the lower side.

[0016] A rotatably supported rotary shaft is provided inside the central housing 101a, extending along the longitudinal direction of the hoist body 101, and a sprocket 7 is provided on this rotary shaft. A chain 9 is hung on the sprocket 7. A load hook 8 is provided on the other end of the chain 9. A load, i.e., a suspended load, can be hooked onto this load hook 8.

[0017] The motor housing 101b houses the electric motor 1 for driving the sprocket 7 to rotate, and a control device 10 for controlling the operation of the electric motor 1 and the electromagnetic brake 3. The electric motor 1 is a three-phase induction motor (three-phase motor) having a rotor, a stator, etc., and is connected to a power source (three-phase AC power source) 102 via a cable 12. The electric motor 1 is driven (rotates forward or reverse) by the power supplied from the power source 102. The rotor of the electric motor 1 is connected to a main shaft.

[0018] The reducer housing 101c houses a reducer 2 and an electromagnetic brake 3. The reducer 2 is made up of a plurality of gears and is connected to the main shaft of the electric motor 1. The reducer 2 reduces the rotation of the main shaft of the electric motor 1 and transmits it to the sprocket 7. The electromagnetic brake 3 is attached to the electric motor 1. The electromagnetic brake 3 is made up of a coil and is actuated by electromagnetic force generated when current is passed through it to brake the electric motor 1.

[0019] The operation input device 5 accepts operations performed by a user to instruct the operation of the electric motor 1. The operation input device 5 is connected to a control device 10 provided inside the hoist main body 101 via a cable 11. The operation input device 5 is provided with an on operation switch 50, an off operation switch 51, an up operation switch 52, and a down operation switch 53.

[0020] The ON switch 50 is an a-contact that is operated by the user when power is supplied to the electric motor 1 to put the electric motor 1 into a drivable state. The OFF switch 51 is a b-contact that is operated by the user when the drivable state of the electric motor 1 is to be ended.

[0021] The upward operation switch 52 is an a-contact that is operated by the user when the load hook 8 is to be hoisted upward. When the upward operation switch 52 is pressed down, the electric motor 1 is driven in the forward direction, causing the sprocket 7 to rotate forward. The forward rotation of the sprocket 7 causes the load hook 8 to move upward, i.e., in the hoisting direction. When the load hook 8 moves in the hoisting direction, one end of the chain 9 enters the chain bucket 6. In other words, the upward operation switch 52, which is the second switch, is a switch that instructs the electric motor 1 to be driven so that the load hook 8 moves upward.

[0022] The downward operation switch 53 is an a-contact that is operated by the user when lowering the load hook 8 downward. When the downward operation switch 53 is pressed down, the electric motor 1 is driven in reverse, causing the sprocket 7 to rotate in reverse. The reverse rotation of the sprocket 7 causes the load hook 8 to move downward, i.e., in the lowering direction. When the load hook 8 moves in the lowering direction, the chain 9 is paid out from the chain bucket 6. In other words, the downward operation switch 53, which is the third switch, is a switch that instructs the electric motor 1 to be driven so that the load hook 8 moves downward.

[0023] The above-mentioned ON switch 50, OFF switch 51, up switch 52, and down switch 53 are self-resetting switches. In the following description, the ON switch 50 may be referred to as the first switch, the up switch 52 as the second switch, and the down switch 53 as the third switch.

[0024] <Control device 10> As shown in Fig. 3, the control device 10 has a low-voltage transformer 20, a power ON / OFF electromagnetic contactor 21, an overwinding prevention device 22, an electromagnetic contactor 23, a main circuit 31, and an operation circuit 32. The main circuit 31 is a circuit that connects the electric motor 1 and a power source 102. The operation circuit 32 is a circuit that is connected to the operation input device 5. The operation circuit 32 is connected to the main circuit 31 via the low-voltage transformer 20. The voltage of the power source 102 is reduced by the low-voltage transformer 20 and supplied to the operation circuit 32. In the following description, the main circuit 31 may be referred to as the first circuit, and the operation circuit 32 may be referred to as the second circuit.

[0025] <Power ON / OFF Electromagnetic Contactor 21> The power ON / OFF electromagnetic contactor 21 is provided to place the electric motor 1 in a state in which it can be driven in response to the depression of the ON switch 50, which is the first switch. The power ON / OFF electromagnetic contactor 21 has a main contact 210, a sub-contact 211, and a coil 212. The main contact 210 is provided in the main circuit 31, which is the first circuit. The main contact 210 is a switch that opens and closes to connect or disconnect the power source 102 and the electric motor 1.

[0026] The sub-contact 211 and the coil 212 are provided in the operation circuit 32, which is the second circuit. The sub-contact 211 is a switch that opens and closes to connect or disconnect the operation input device 5 to the operation circuit 32. Specifically, the sub-contact 211 is provided in series with an upward overwinding prevention device 221 and a downward overwinding prevention device 222, which will be described later, on a path 32b that connects the ON operation switch 50 and the OFF operation switch 51, and is connected to one end of the secondary side of the low-voltage transformer 20. The coil 212 is provided on a path 32a that connects the ON operation switch 50 and the OFF operation switch 51, and is connected to one end of the secondary side of the low-voltage transformer 20.

[0027] <Overwinding prevention device 22> The overwinding prevention device 22 is composed of an upward overwinding prevention device 221 and a downward overwinding prevention device 222. The upward overwinding prevention device 221 and the downward overwinding prevention device 222 are connected to the operation circuit 32, which is the second circuit. The upward overwinding prevention device 221 is a first limit switch that is activated, for example, by a lever swinging in a predetermined direction when it comes into contact with the load hook 8 that has been wound upward and reached its upper limit position. The upward overwinding prevention device 221 is provided on a path 32b on the operation circuit 32 and on a path 32d connected to the upward operation switch 52.

[0028] The downward overwinding prevention device 222 is a second limit switch that is activated, for example, by a lever swinging in a predetermined direction when it comes into contact with one end of the chain 9 when the load hook 8, which has been lowered downward, reaches its lowest position. The downward overwinding prevention device 222 is provided on a path 32b on the operation circuit 32 and on a path 32c connected to the downward operation switch 53. That is, on path 32b, the upward overwinding prevention device 221, the downward overwinding prevention device 222, and the auxiliary contact 211, which is the second contact of the power ON / OFF electromagnetic contactor 21, are connected in series.

[0029] When the overwinding prevention device 22 is activated, the operating circuit 32 is opened. As will be described in detail later, opening of the operating circuit 32 cuts off the power supply to the electric motor 1, forcibly stopping the drive of the electric motor 1. In other words, the overwinding prevention device 22 stops the power supply to the electric motor 1 when the load hook 8 reaches the upper limit position or the lower limit position due to the drive of the electric motor 1. In other words, the load hook 8 can move up or down between the lower limit position and the upper limit position.

[0030] <Electromagnetic Contactor 23> The electromagnetic contactor 23 includes an upward electromagnetic contactor 231 and a downward electromagnetic contactor 232. The upward electromagnetic contactor 231 and the downward electromagnetic contactor 232 each include a contact 233 and a coil 234. The contact 233 is provided in the main circuit 31, and the coil 234 is provided in the operation circuit 32. The coil 234 of the upward electromagnetic contactor 231 is provided in series with the upward overwinding prevention device 221 on path 32d and connected to the other end of the secondary side of the low-voltage transformer 20. The coil 234 of the downward electromagnetic contactor 232 is provided in series with the downward overwinding prevention device 222 on path 32c and connected to the other end of the secondary side of the low-voltage transformer 20. Note that the upward overwinding prevention device 221 does not necessarily have to be connected to path 32d, and the downward overwinding prevention device 222 does not necessarily have to be connected to path 32c.

[0031] <Operation of the control device 10> The operation of the control device 10 having the above configuration will be described. When the user presses the ON operation switch 50 to start operation of the hoist 100, the coil 212 of the power ON / OFF electromagnetic contactor 21 is energized. When the coil 212 is energized, the main contact 210 and the sub-contact 211 are closed. As a result, the operation circuit 32 forms a self-holding circuit that maintains a state in which it is energized by the power source 102 via the low-voltage transformer 20. In other words, even when the ON operation switch 50 is not pressed, the operation circuit 32 maintains a state in which it is energized. At this time, the electric motor 1 is in a state in which it can be energized and driven, and when the user presses the up operation switch 52 or the down operation switch 53, the electric motor 1 is energized and the hoist 100 is driven.

[0032] When the upward operation switch 52 is pressed while the motor is in the drivable state, the coil 234 of the upward electromagnetic contactor 231 is energized and the contact 233 is closed. This energizes the motor 1, releases the electromagnetic brake 3, and the motor 1 rotates forward as described above. As a result, the load hook 8 is reeled in upward.

[0033] When the load hook 8 is wound upward and reaches the upper limit position, the upward overwinding prevention device 221 is activated. That is, the contacts of the upward overwinding prevention device 221, which is the first limit switch, open, and the self-holding circuit formed in the operation circuit 32 is released. As a result, current is cut off to the coil 212 of the power ON / OFF electromagnetic contactor 21. This opens the main contact 210 and the sub-contact 211 of the power ON / OFF electromagnetic contactor 21, and current to the electric motor 1 is stopped. As a result, the load hook 8 is prevented from being wound upward above the upper limit position.

[0034] When the downward operation switch 53 is pressed while the motor is in the drivable state, the coil 234 of the downward electromagnetic contactor 232 is energized and the contact 233 is closed. This energizes the motor 1, releases the electromagnetic brake 3, and causes the motor 1 to rotate in the reverse direction as described above. As a result, the load hook 8 is reeled down.

[0035] When the load hook 8 is lowered downward and reaches the lower limit position, the downward overwinding prevention device 222 is activated. That is, the contacts of the downward overwinding prevention device 222, which is the second limit switch, open, and the self-holding circuit formed in the operation circuit 32 is released. This cuts off the power to the coil 212 of the power ON / OFF electromagnetic contactor 21. This opens the main contact 210 and the sub-contact 211 of the power ON / OFF electromagnetic contactor 21, and stops the power to the electric motor 1. As a result, the load hook 8 is prevented from being lowered below the lower limit position.

[0036] Next, the operations performed by the user after the load hook 8 reaches the upper limit position or the lower limit position and the over-winding prevention device 22 is activated will be described, as well as the operation of the hoist 100. After the over-winding prevention device 22 is activated, the user continues to press the ON operation switch 50, and then presses the up operation switch 52 or the down operation switch 53. Specifically, when the load hook 8 reaches the upper limit position and the upward over-winding prevention device 221 is activated (the contacts are open), the user continues to press the ON operation switch 50, and then presses the down operation switch 53 to lower the load hook 8 downward.

[0037] While the ON switch 50 is pressed down as described above, the coil 212 of the power ON / OFF electromagnetic contactor 21 is energized, and the energization of the coil 212 closes the main contact 210 and the sub-contact 211. When the downward operation switch 53 is pressed down in this state, the coil 234 of the downward electromagnetic contactor 232 on the path 32c is energized, and the contact 233 is closed. This energizes the electric motor 1, releases the electromagnetic brake 3, and drives the electric motor 1 in the reverse direction described above. That is, the electric motor 1 drives the load hook 8 downward. In other words, after the upward overwinding prevention device 221, which is the first limit switch, is opened, if the downward operation switch 53, which is the third switch, is operated while the ON switch 50, which is the first switch, is still operated, the electric motor 1 drives in a direction that moves the load hook 8 downward.

[0038] When the load hook 8 is lowered downward and reaches a position lower than the upper limit position, the upward overwinding prevention device 221 is deactivated and the contacts are closed (deactivated). As a result, the operation circuit 32 forms a self-holding circuit. Therefore, the load hook 8 can be wound up or lowered by pressing the upward operation switch 52 or the downward operation switch 53 without continuously pressing the on operation switch 50. In other words, the load hook 8 can be temporarily operated by pressing the downward operation switch 53 while the on operation switch 50 is continuously pressed.

[0039] When the load hook 8 reaches the lowest position and the downward overwinding prevention device 222 is activated (the contacts are open), the upward operation switch 52 for winding the load hook 8 upward is pressed while the on operation switch 50 is continuously pressed. In this case, too, while the on operation switch 50 is being pressed, the coil 212 of the power on / off electromagnetic contactor 21 is energized, and the energization of the coil 212 closes the main contact 210 and the sub-contact 211. When the upward operation switch 52 is pressed in this state, the coil 234 of the upward electromagnetic contactor 231 on the path 32d is energized, and the contact 233 is closed.

[0040] As a result, current is applied to the electric motor 1, the electromagnetic brake 3 is released, and the electric motor 1 rotates in the forward direction as described above. As a result, the load hook 8 is hoisted upward. In other words, after the downward over-winding prevention device 222 (second limit switch) opens, if the upward operation switch 52 (second switch) is operated while the on operation switch 50 (first switch) is still operated, the electric motor 1 is driven in a direction that moves the load hook 8 downward.

[0041] When the load hook 8 is positioned above the lower limit position due to upward winding, the downward overwinding prevention device 222 is deactivated and the contacts are closed, resulting in an inactive state. As a result, the operation circuit 32 forms a self-holding circuit. That is, the load hook 8 can be wound up or lowered by pressing the up-direction operation switch 52 or the down-direction operation switch 53 without continuously pressing the on-operation switch 50. In other words, the load hook 8 can be temporarily operated by pressing the up-direction operation switch 52 while the on-operation switch 50 is continuously pressed.

[0042] As described above, when the overwinding prevention device 22 is inactive, if the first switch, the ON operation switch 50, is pressed down, the sub-contact 211 is maintained in a closed state, and the operation circuit 32 forms a self-holding circuit. In contrast, after the overwinding prevention device 22 is activated, the operation circuit 32 does not form a self-holding circuit, and the sub-contact 211 is closed only while the first switch, the ON operation switch 50, is pressed down. Then, if the motor 1 is driven by operating the up-direction operation switch 52 or the down-direction operation switch 53 while the ON operation switch 50 is in an operated state, and then the overwinding prevention device 22 is deactivated, the sub-contact 211 is closed, and the operation circuit 32 again forms a self-holding circuit.

[0043] When the load hook 8 is in a state where it can move between the upper limit position and the lower limit position, i.e., when the operation circuit 32 forms a self-holding circuit, pressing down the off-operation switch 51 stops the operation of the hoist 100. In this case, pressing down the off-operation switch 51 opens the auxiliary contact 211, and cuts off the power to the coil 212 of the power on / off electromagnetic contactor 21. Cutting off the power to the coil 212 of the power on / off electromagnetic contactor 21 opens the main contact 210 of the power on / off electromagnetic contactor 21, and cuts off the power to the electric motor 1.

[0044] When the hoist 100 is installed, the load hook 8 is often wound up to a position close to the upper limit position, as shown in Figures 1 and 2. For this reason, when the hoist 100 is used for the first time after installation, the on-operation switch 50 is pressed to form a self-holding circuit, and then the down-operation switch 53 is pressed, and the load hook 8 is often wound down. At this time, if the hoist 100 is connected in reverse phase to the power source 102, the electric motor 1 rotates forward, and the load hook 8 is wound up upward, even though the down-operation switch 53 for lowering has been pressed down.

[0045] However, when the load hook 8 is wound up and reaches the upper limit position, the upward overwinding prevention device 221 is activated as described above. This opens the main contact 210 and the sub-contact 211 of the power ON / OFF electromagnetic contactor 21, cutting off the power supply to the electric motor 1 and disabling the self-holding circuit formed in the operation circuit 32, preventing the load hook 8 from being wound up above the upper limit position. Therefore, even when the hoisting machine 100 is connected in reverse phase, it is possible to prevent the load hook 8 from being overwinded.

[0046] Furthermore, even though the user pressed down the downward operation switch 53 intending to lower the load hook 8, the load hook 8 was actually hoisted up, which allows the user to recognize that the hoisting machine 100 is in a reverse phase connection. In this case, the user corrects the incorrect wiring between the electric motor 1 and the power supply 102 to a positive phase connection before using the hoisting machine 100. Therefore, there is no need to incorporate a complex structure such as a reverse phase reversal relay into the control device 10.

[0047] According to the above-described embodiment, at least one of the following advantageous effects can be obtained: (1) The control device 10 of the embodiment includes a main circuit 31, which is a first circuit, an operation circuit 32, which is a second circuit, a power ON / OFF electromagnetic contactor 21, and an overwinding prevention device 22 connected to the operation circuit 32. The power ON / OFF electromagnetic contactor 21 has a main contact 210 provided in the main circuit 31, and an auxiliary contact 211 and a coil 212 provided in the operation circuit 32.

[0048] FIG. 4 is a connection diagram showing the control configuration of a comparative hoist that differs from the present embodiment. In the comparative example shown in FIG. 4, components that are the same as or substantially the same as those of the present embodiment shown in FIGS. 1 to 3 are assigned the same reference numerals. A control device 10A for a hoist in the comparative example includes a low-voltage transformer 20, an overwinding prevention device 22A, an electromagnetic contactor 23A, a main circuit 31, an operation circuit 321, and a reverse-phase prevention device 40. However, the control device 10A does not include the power-on / off electromagnetic contactor 21 of the embodiment. An operation input device 5A connected to the control device 10A includes an up-direction operation switch 52 and a down-direction operation switch 53.

[0049] The reverse phase prevention device 40 is connected to the main circuit 31 that connects the power supply 102 and the electric motor 1. The reverse phase prevention device 40 detects whether the connection between the power supply 102 and the control device 10A is positive or negative phase, and closes a contact 41 provided in the operation circuit 321 if the phase is positive, and opens the contact 41 if the phase is negative. When the contact 41 is closed, the electric motor 1 can be driven in response to pressing of the up operation switch 52 or the down operation switch 53. However, since the operation input device 5A does not have the on operation switch 50 and the off operation switch 51 of the embodiment, the operation circuit 321 does not form a self-holding circuit.

[0050] Moreover, the overwinding prevention device 22A has an upward overwinding prevention device 221A and a downward overwinding prevention device 222A. The upward overwinding prevention device 221A is composed of a limit switch 223 provided in the main circuit 31 and a limit switch 224 provided in the operation circuit 321. The downward overwinding prevention device 222A is composed of a limit switch 225 provided in the main circuit 31 and a limit switch 226 provided in the operation circuit 321. The limit switches 223, 225 that the upward overwinding prevention device 221A and the downward overwinding prevention device 222A have in the main circuit 31 have larger contacts than the limit switches 224, 226 provided in the operation circuit 321 because the current flowing in the main circuit 31 is larger than the current flowing in the operation circuit 321.

[0051] When the upward operation switch 52 is operated after the connection of the positive phase is detected and the contact 41 is closed, the coil 234 constituting the upward electromagnetic contactor 231 of the electromagnetic contactor 23 is energized, and the contact 233 of the upward electromagnetic contactor 231 provided in the main circuit 31 is closed. As a result, the electric motor 1 is energized via the limit switch 223 of the upward overwinding prevention device 221A. At this time, the electromagnetic brake 3 is also energized, the electromagnetic brake 3 is released, and the electric motor 1 is driven in the forward direction.

[0052] When downward operation switch 53 is operated after the connection of the positive phase is detected and contact 41 is closed, coil 234 constituting downward electromagnetic contactor 232 of electromagnetic contactor 23 is energized, and contact 233 of downward electromagnetic contactor 232 provided in main circuit 31 is closed. As a result, electric motor 1 is energized via limit switch 225 of downward overwinding prevention device 222A. At this time, electromagnetic brake 3 is also energized, electromagnetic brake 3 is released, and electric motor 1 is driven in reverse rotation.

[0053] When the load hook 8 reaches the upper limit position due to the forward rotation of the motor 1, the limit switches 223 and 224 of the upward overwinding prevention device 221A open, and power to the motor 1 is cut off. When the load hook 8 reaches the lower limit position due to the reverse rotation of the motor 1, the limit switches 225 and 226 of the downward overwinding prevention device 222A open, and power to the motor 1 is cut off.

[0054] In contrast to the comparative example having the above-described configuration and operation, the control device 10 of this embodiment does not have the reverse phase prevention device 40 or the contact 41, but has the power ON / OFF electromagnetic contactor 21. When the first switch, the ON operation switch 50, is operated to energize the coil 212, the main contact 210 and the sub-contact 211 close, and the operation circuit 32 forms a self-holding circuit. When the overwinding prevention device 22 operates while the electric motor 1 is running, the self-holding circuit formed by the operation circuit 32 is released, the main contact 210 and the sub-contact 211 open, and the supply of electricity to the electric motor 1 is stopped.

[0055] As a result, since the reverse phase prevention device 40 is not provided, when the reverse phase is connected, the electric motor 1 will drive, but excessive hoisting or excessive lowering is prevented by the over-hoisting prevention device 22. Therefore, without providing the reverse phase prevention device 40, breakdown of the hoisting machine 100, dropping of the suspended load, etc. are prevented, and safety is ensured.

[0056] Furthermore, although the reverse phase prevention device 40 has a complex structure, it is an unnecessary configuration after correcting the reverse phase connection of the hoisting machine 100 to a positive phase connection, or when the hoisting machine 100 has been in a positive phase connection since installation. The control device 10 of this embodiment does not include the reverse phase prevention device 40, which becomes unnecessary in the case of a positive phase connection, and therefore simplifies the manufacture of the control device 10 and the hoisting machine 100 including the control device 10, which can contribute to reducing manufacturing costs.

[0057] Moreover, the overwinding prevention device 22 in this embodiment is a limit switch provided in the operation circuit 32. When the operation circuit 32 releases the self-holding circuit, the main contact 210 of the power ON / OFF electromagnetic contactor 21 opens, thereby stopping the flow of current to the electric motor 1, eliminating the need to provide the limit switch constituting the overwinding prevention device 22 in the main circuit 31. Therefore, unlike the limit switch of the comparative example which is provided in the main circuit 31, measures such as increasing the size of the limit switch of the overwinding prevention device 22 depending on the current flowing through the electric motor 1 are not required.

[0058] Furthermore, when the over-winding prevention device 22 is not activated, the sub-contact 211 of the power ON / OFF electromagnetic contactor 21 is closed, causing the operation circuit 32 to form a self-holding circuit. Therefore, by the user pressing the up operation switch 52 or the down operation switch 53, the load hook 8 can be hoisted up or down, allowing the hoist 100 to function as a hoist.

[0059] (2) The first switch, the ON switch 50, is a self-resetting switch. When the overwinding prevention device 22 is not activated, the sub-contact 211 is maintained in a closed state when the ON switch 50 is operated. This allows the load hook 8 to be moved in the hoisting or lowering direction in response to the pressing of the up-direction operation switch 52 or the down-direction operation switch 53.

[0060] Furthermore, after the overwinding prevention device 22 is activated while the motor 1 is running, the sub-contact 211 is closed only while the on-operation switch 50 is being operated. In other words, the operation circuit 32 no longer forms a self-holding circuit. This prevents the user from accidentally touching the up-operation switch 52 or the down-operation switch 53, which would otherwise cause the motor 1 to start, thereby ensuring safety.

[0061] (3) The upward overwinding prevention device 221, which is the first limit switch of the overwinding prevention device 22, and the downward overwinding prevention device 222, which is the second limit switch, and the sub-contact 211 of the power ON / OFF electromagnetic contactor 21 are connected in series to the second circuit, the operating circuit 32. As a result, when the load hook 8 reaches the upper limit position or the lower limit position, the current to the coil 212 is stopped and the main contact 210 and the sub-contact 211 are opened, so that the current to the electric motor 1 can be reliably stopped.

[0062] (4) After the upward overwinding prevention device 221 opens, if the third switch, the downward operation switch 53, is pressed while the ON operation switch 50 is pressed, the electric motor 1 drives in a direction that moves the load hook 8 downward. Also, after the downward overwinding prevention device 222 opens, if the second switch, the upward operation switch 52, is pressed while the ON operation switch 50 is pressed, the electric motor 1 drives in a direction that moves the load hook 8 upward. This makes it possible to temporarily make the hoist 100, which has been made inoperable by the overwinding prevention device 22, operable.

[0063] (5) When the up operation switch 52 or the down operation switch 53 is operated while the on operation switch 50 is pressed down, the motor 1 is driven, and then the overwinding prevention device 22 is deactivated, the auxiliary contact 211 is closed and the operation circuit 32 forms a self-holding circuit. This allows the hoist 100 to be again in a state where it can be hoisted up or down in response to the user's operation.

[0064] The present invention is not limited to the details described in the above embodiment. Other embodiments conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention. For example, the hoist is not limited to an electric chain hoist, and may be a hoist in which a wire serving as a cargo cable is wound around a drum serving as a rotating body.

[0065] 1 Electric motor, 5 Operation input device, 8 Load hook, 10 Control device, 21 Power on / off electromagnetic contactor, 22 Overwinding prevention device, 31 Main circuit, 32 Operation circuit, 50 On operation switch, 51 Off operation switch, 52 Upward operation switch, 53 Downward operation switch, 100 Hoist, 101 Hoist body, 102 Power supply, 210 Main contact, 211 Sub-contact, 212 Coil, 221 Upward overwinding prevention device, 222 Downward overwinding prevention device

Claims

1. A control device for a hoist, comprising: a first circuit to which a power source and a motor are connected; a second circuit to which an operation input device for receiving an operation for instructing the operation of the motor is connected; a first contact provided in the first circuit for connecting or disconnecting the power source and the motor by opening and closing; a coil provided in the second circuit; and a second contact provided in the second circuit for connecting or disconnecting the operation input device from the second circuit by opening and closing. An electromagnetic contactor for power supply on / off that can drive the motor in response to an operation of a first switch of the operation input device; and an overwind prevention device connected to the second circuit for stopping energization of the motor when a load hook for hooking a load reaches an upper limit position or a lower limit position by driving the motor. When the first switch is operated and the coil is energized, the first contact and the second contact are closed to form a self-holding circuit in which the second circuit maintains an energized state. When the overwind prevention device operates during the driving of the motor, the self-holding circuit formed by the second circuit is released, the first contact and the second contact are opened, and the energization of the motor is stopped.

2. The control device for a hoist according to claim 1, wherein the first switch is a self-return type switch, and when the overwind prevention device is not operating, when the first switch is operated, the state where the second contact is closed is maintained, and after the overwind prevention device operates during the driving of the motor, the second contact is closed only while the first switch is being operated.

3. The control device for a hoist according to claim 2, wherein the overwind prevention device includes a first limit switch that opens when the load hook reaches the upper limit position and a second limit switch that opens when the load hook reaches the lower limit position, and the first limit switch, the second limit switch, and the second contact are connected in series in the second circuit.

4. In the control device for a winch according to claim 3, the operation input device includes a second switch for instructing the drive of the electric motor so that the load hook moves upward, and a third switch for instructing the drive of the electric motor so that the load hook moves downward. When the third switch is operated while the first switch is in an operated state after the first limit switch is opened, the electric motor is driven in a direction to move the load hook downward. When the second switch is operated while the first switch is in an operated state after the second limit switch is opened, the electric motor is driven in a direction to move the load hook upward. A control device for a winch.

5. In the control device for a winch according to claim 4, when the anti-overwinding device becomes inoperative after the electric motor is driven by operating the second switch or the third switch while the first switch is in an operated state, the second contact closes and the second circuit forms a self-holding circuit. A control device for a winch.

6. An electric motor driven by electric power supplied from a power source, an operation input device that receives an operation for instructing the operation of the electric motor, and a control device that controls the driving of the electric motor according to the operation received by the operation input device. The control device includes a first circuit to which the power source and the electric motor are connected, a second circuit to which the operation input device is connected, a first contact provided in the first circuit and configured to connect or disconnect the power source and the electric motor by opening and closing, a coil provided in the second circuit, and a second contact provided in the second circuit and configured to connect or disconnect the operation input device from the second circuit by opening and closing. An electromagnetic contactor for turning on and off the power supply that enables the electric motor to be driven according to the operation of a first switch included in the operation input device, and an overwind prevention device connected to the second circuit and configured to stop energization of the electric motor when a load hook that hooks a suspended load reaches an upper limit position or a lower limit position due to the driving of the electric motor. When the first switch is operated and the coil is energized, the first contact and the second contact close to form a self-holding circuit that keeps the second circuit energized. When the overwind prevention device operates during the driving of the electric motor, the self-holding circuit formed by the second circuit is released, the first contact and the second contact open, and the energization of the electric motor is stopped. A hoist.

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