Control device for hoisting machine and hoisting machine

Abstract

To provide a control device for a hoisting machine that achieves both safety and functionality of the hoisting machine without using a reversed-phase inversion relay.SOLUTION: A control device 10 for a hoisting machine comprises a main circuit 31 to which a power source 102 and an electric motor 1 are connected, an operation circuit 32 to which an operation input device 5 is connected, a power source ON / OFF electromagnetic contactor 21 having a main contact 210 provided in the main contact 31 and a coil 212 and a sub contact 211 provided in the operation circuit 32, and an overhoisting prevention device 22 connected to the operation circuit 32 and that stops electric power supply to the electric motor 1 when a load hook reaches an upper limit position or a lower limit position. When an 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 overhoisting prevention device 22 operates 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 open, and the electric power supply to the electric motor 1 is stopped.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[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 motor are connected in positive phase, and supplies phase-reversed power to the motor when the power supply and motor are connected in negative phase. This allows the motor to operate in the same way as when connected in positive phase, even when the power supply and 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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-20495 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[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, and is equipped with a power on / off 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 cuts 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 drive 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] A hoist according to an embodiment includes 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. The hoist further includes a power supply electromagnetic contactor configured to bring the electric motor into a drivable state according to an 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 driving of the electric motor. When the first switch is operated and the coil is energized, the first contact and the second contact are closed, and the second circuit forms a self-holding circuit that maintains an energized state. When the overwind prevention device operates during driving of the electric motor, the self-holding circuit formed by the second circuit is released, the first contact and the second contact are opened, and energization of the electric motor is stopped.

Effects of the Invention

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

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0011] Hereinafter, the winch according to an embodiment of the present invention will be described in detail with reference to the drawings. Hereinafter, an electric chain block will be used as an example of the winch for explanation, but the winch is not limited to the electric chain block.

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

[0013] The winch 100 includes a winch main body 101, an electric motor 1, a speed reducer 2, an electromagnetic brake 3, an upper sling 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 winch main body 101 has a rectangular parallelepiped shape and includes a central housing 101a, a motor housing 101b, and a speed reducer housing 101c. The central housing 101a is provided at the central portion in the longitudinal direction of the winch main body 101. The motor housing 101b is provided on one side of the central housing 101a in the longitudinal direction of the winch main body 101. The speed reducer housing 101c is provided on the other side of the central housing 101a in the longitudinal direction of the winch main body 101.

[0015] The upper sling 4 is attached to the surface 101d on one side of the central housing 101a. The winch 100 is used in a state of being suspended by this upper sling 4. The chain bucket 6 is attached to the surface 101e on the other side of the central housing 101a. The chain bucket 6 is a chain container that houses one end side 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] Inside the central housing 101a, a rotating shaft is provided that extends along the longitudinal direction of the hoisting machine body 101 and is rotatably supported, and a sprocket 7 is provided on this rotating shaft. A chain 9 is looped around the sprocket 7. At the other end of the chain 9, a load hook 8 is provided. A load, that is, a suspended load, can be hooked onto this load hook 8.

[0017] Inside the motor housing 101b, an electric motor 1 for rotationally driving the sprocket 7 and a control device 10 for controlling the operations of the electric motor 1 and the electromagnetic brake 3 are arranged. 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 backward) by the electric power supplied from the power source 102. The rotor of the electric motor 1 is connected to the main shaft.

[0018] Inside the speed reducer housing 101c, a speed reducer 2 and an electromagnetic brake 3 are arranged. The speed reducer 2 is composed of a plurality of gears, etc., and is connected to the main shaft of the electric motor 1. The speed 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 composed of a coil, etc., and operates using the electromagnetic force generated by energization to brake the electric motor 1.

[0019] The operation input device 5 receives an operation for instructing the operation of the electric motor 1 performed by the user. The operation input device 5 is connected to the control device 10 provided inside the hoisting machine 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 upward operation switch 52, and a downward operation switch 53.

[0020] The on operation switch 50 is an a contact that is operated by the user when power supply to the electric motor 1 is performed to make the electric motor 1 drivable. The off operation switch 51 is a b contact that is operated by the user when ending the drivable state of the electric motor 1.

[0021] The upward operation switch 52 is an a-contact that is operated by the user when the load hook 8 is to be wound up in the upward direction. 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 winding direction. When the load hook 8 moves in the winding 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 and the sprocket 7 rotates 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 unwound 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 includes a low-voltage transformer 20, a power supply on / off electromagnetic contactor 21, an over-winding 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 motor 1 and the power supply 102. The operation circuit 32 is a circuit 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 power of the power supply 102 is supplied to the operation circuit 32 after its voltage is reduced by the low-voltage transformer 20. 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 supply on / off electromagnetic contactor 21> The power supply on / off electromagnetic contactor 21 is provided to make the motor 1 drivable in response to the pressing operation of the on-operation switch 50, which is the first switch. The power supply 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 connects or disconnects the power supply 102 and the motor 1 by opening and closing.

[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 connects or disconnects the operation circuit 32 of the operation input device 5 by opening and closing. Specifically, the sub-contact 211 is provided in series with the upward over-winding prevention device 221 and the downward over-winding prevention device 222, which will be described later, on the path 32b connected to 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 the path 32a connected to the on-operation switch 50 and is connected to one end of the secondary side of the low-voltage transformer 20.

[0027] <Over-winding 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 an operation circuit 32 which is a second circuit. The upward overwinding prevention device 221 is a first limit switch that operates, for example, when a lever swings in a predetermined direction by contacting a load hook 8 that has been wound upward and reached the upper limit position. The upward overwinding prevention device 221 is provided on a path 32b on the operation circuit 32 and a path 32d connected to an upward operation switch 52.

[0028] The downward overwinding prevention device 222 is a second limit switch that operates, for example, when a lever swings in a predetermined direction by contacting one end side of a chain 9 when a load hook 8 wound downward reaches the lower limit position. The downward overwinding prevention device 222 is provided on a path 32b on the operation circuit 32 and a path 32c connected to a downward operation switch 53. That is, in the path 32b, the upward overwinding prevention device 221, the downward overwinding prevention device 222, and a sub-contact 211 which is a second contact of an electromagnetic contactor 21 for power on / off are connected in series.

[0029] When the overwinding prevention device 22 operates, the operation circuit 32 is opened. As will be described in detail later, with the opening of the operation circuit 32, the power supply to the motor 1 is cut off, and the drive of the motor 1 is forcibly stopped. That is, when the load hook 8 reaches the upper limit position or the lower limit position by the drive of the motor 1, the overwinding prevention device 22 stops the power supply to the 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 have 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 winding prevention device 221 on the path 32d and is 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 winding prevention device 222 on the path 32c and is connected to the other end of the secondary side of the low-voltage transformer 20. Note that the upward winding prevention device 221 may not be connected on the path 32d, and the downward winding prevention device 222 may not be connected on the 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 input operation switch 50 at the start of the 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 auxiliary contact 211 are closed. As a result, the operation circuit 32 forms a self-holding circuit that maintains the state of being energized by the power supply 102 via the low-voltage transformer 20. That is, even when the input operation switch 50 is not being pressed, the operation circuit 32 remains energized. At this time, the electric motor 1 is in a drivable state where it can be energized, and when the upward operation switch 52 or the downward operation switch 53 is pressed by the user, the electric motor 1 is energized and the hoist 100 is driven.

[0032] When the upward operation switch 52 is pressed in the drivable state, the coil 234 of the upward electromagnetic contactor 231 is energized and the contact 233 is closed. As a result, the electric motor 1 is energized and the electromagnetic brake 3 is released, and the electric motor 1 performs the above-described forward rotation. As a result, the load hook 8 is wound upward.

[0033] When the load hook 8 is wound upward and reaches the upper limit position, the upward winding prevention device 221 operates. That is, the contact of the upward winding prevention device 221, which is the first limit switch, opens, and the self-holding circuit formed in the operation circuit 32 is released. For this reason, the energization to the coil 212 of the power cut-off electromagnetic contactor 21 is cut off. As a result, the main contact 210 and the auxiliary contact 211 of the power cut-off electromagnetic contactor 21 open, and the energization to the motor 1 is stopped. As a result, the load hook 8 is prevented from being wound upward beyond the upper limit position.

[0034] When the downward operation switch 53 is pressed during the drivable state, the coil 234 of the downward electromagnetic contactor 232 is energized, and the contact 233 closes. As a result, the motor 1 is energized and the electromagnetic brake 3 is released, and the motor 1 performs the reverse rotation described above. As a result, the load hook 8 is wound downward.

[0035] When the load hook 8 is wound downward and reaches the lower limit position, the downward winding prevention device 222 operates. That is, the contact of the downward winding prevention device 222, which is the second limit switch, opens, and the self-holding circuit formed in the operation circuit 32 is released. For this reason, the energization to the coil 212 of the power cut-off electromagnetic contactor 21 is cut off. As a result, the main contact 210 and the auxiliary contact 211 of the power cut-off electromagnetic contactor 21 open, and the energization to the motor 1 is stopped. As a result, the load hook 8 is prevented from being wound downward beyond the lower limit position.

[0036] Next, after the load hook 8 reaches the above upper limit position or lower limit position and the winding prevention device 22 operates, the operations performed by the user and the operations of the hoisting machine 100 will be described. After the winding prevention device 22 operates, the upward operation switch 52 or the downward operation switch 53 is pressed while the input operation switch 50 is continuously pressed by the user. Specifically, when the load hook 8 reaches the upper limit position and the upward winding prevention device 221 is operating (the contact is open), the downward operation switch 53 for winding the load hook 8 downward is pressed while the input operation switch 50 is continuously pressed.

[0037] While the ON switch 50 is being pressed in the above operation, 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 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 rotation described above. That is, the electric motor 1 drives the load hook 8 in the direction of lowering the load hook 8. 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 the direction of moving 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 lower limit position and the downward winding prevention device 222 is operating (contacts are open), with the input operation switch 50 being continuously pressed, the upward operation switch 52 for winding up the load hook 8 upward is pressed. Also in this case, while the input operation switch 50 is being pressed, the coil 212 of the power on / off electromagnetic contactor 21 is energized, and due to the energization of the coil 212, the main contact 210 and the auxiliary contact 211 are closed. 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, the motor 1 is energized and the electromagnetic brake 3 is released, and the motor 1 performs the above-described forward rotation. Consequently, the load hook 8 is wound up upward. In other words, after the downward winding prevention device 222, which is the second limit switch, is opened, when the upward operation switch 52, which is the second switch, is operated while the input operation switch 50, which is the first switch, is being operated, the motor 1 is driven in the direction to move the load hook 8 downward.

[0041] When the load hook 8 is positioned above the lower limit position by being wound up upward, the operation of the downward winding prevention device 222 is released, and it becomes a non-operating state where the contacts are closed. As a result, the operation circuit 32 forms a self-holding circuit. That is, without continuously pressing the input operation switch 50, by pressing the upward operation switch 52 or the downward operation switch 53, the load hook 8 can be wound up or down. In other words, by pressing the upward operation switch 52 while the input operation switch 50 is continuously pressed, it becomes possible to temporarily operate the load hook 8.

[0042] As described above, when the anti-overwinding device 22 is inoperative, when the input operation switch 50, which is the first switch, is pressed, the state where the auxiliary contact 211 is closed is maintained, and the operation circuit 32 forms a self-holding circuit. On the other hand, after the anti-overwinding device 22 is activated, the operation circuit 32 does not form a self-holding circuit, and the auxiliary contact 211 is closed only while the input operation switch 50, which is the first switch, is being pressed. Then, when the up-direction operation switch 52 or the down-direction operation switch 53 is operated while the input operation switch 50 is being operated and the motor 1 is driven, and then the anti-overwinding device 22 becomes inoperative, the auxiliary contact 211 is closed and the operation circuit 32 forms a self-holding circuit again.

[0043] When the load hook 8 is in a state where it can move between the upper limit position and the lower limit position, that is, when the operation circuit 32 forms a self-holding circuit, if the cut-off operation switch 51 is pressed, the operation of the hoist 100 stops. In this case, when the cut-off operation switch 51 is pressed, the auxiliary contact 211 opens, and the power supply to the coil 212 of the power supply cut-off electromagnetic contactor 21 is cut off. When the power supply to the coil 212 of the power supply cut-off electromagnetic contactor 21 is cut off, the main contact 210 of the power supply cut-off electromagnetic contactor 21 opens, and the power supply to the motor 1 is stopped.

[0044] When the hoist 100 is installed, as shown in FIGS. 1 and 2, the load hook 8 is often wound up to a position close to the upper limit position. Therefore, when using the hoist 100 for the first time after installation, after the input operation switch 50 is pressed to form a self-holding circuit, the down-direction operation switch 53 is often pressed, and the load hook 8 is wound downwards. At this time, if the hoist 100 is reversely connected to the power supply 102, even though the down-direction operation switch 53 for winding down is being pressed, the motor 1 rotates forward, and the load hook 8 is wound upwards.

[0045] However, when the load hook 8 is hoisted and reaches the upper and lower positions, as described above, the upward overwind prevention device 221 operates. As a result, the main contact 210 and the auxiliary contact 211 of the electromagnetic contactor 21 for power supply on / off open, the power supply to the motor 1 is cut off, the self-holding circuit formed in the operation circuit 32 is released, and the load hook 8 is suppressed from being hoisted above the upper limit position. Therefore, even when the hoisting machine 100 is reversely connected, overwinding of the load hook 8 can be suppressed.

[0046] In addition, even though the user presses the downward operation switch 53 intending to lower the load hook 8, since the load hook 8 is hoisted, the user can recognize that the hoisting machine 100 is reversely connected. In this case, the user corrects the misconnection between the motor 1 and the power supply 102 to be a normal connection and then uses the hoisting machine 100. Therefore, there is no need to incorporate a complicated 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 operational 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, an electromagnetic contactor 21 for power supply on / off, and an overwind prevention device 22 connected to the operation circuit 32. The electromagnetic contactor 21 for power supply on / off has a main contact 210 provided in the main circuit 31, an auxiliary contact 211 and a coil 212 provided in the operation circuit 32.

[0048] FIG. 4 is a connection diagram showing a control configuration of a winch in a comparative example different from the present embodiment. In the comparative example shown in FIG. 4, the same reference numerals are given to the configurations that are the same as or substantially the same as those of the present embodiment shown in FIGS. 1 to 3. The control device 10A of the winch in the comparative example includes a low-voltage transformer 20, an overwind 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 have the power-on / off electromagnetic contactor 21 of the embodiment. Further, the operation input device 5A connected to the control device 10A has an upward operation switch 52 and a downward 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 motor 1. The reverse-phase prevention device 40 detects whether the connection between the power supply 102 and the control device 10A is in the normal phase or the reverse phase. In the case of the normal phase, it closes the contact 41 provided in the operation circuit 321, and in the case of the reverse phase, it opens the contact 41. When the contact 41 is closed, the motor 1 can be driven in response to the pressing operation of the upward operation switch 52 or the downward operation switch 53. However, since the operation input device 5A does not have the input operation switch 50 and the cut operation switch 51 of the embodiment, the operation circuit 321 does not form a self-holding circuit.

[0050] Further, the overwind prevention device 22A includes an upward overwind prevention device 221A and a downward overwind prevention device 222A. The upward overwind 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 overwind 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 respective limit switches 223 and 225 of the upward overwind prevention device 221A and the downward overwind prevention device 222A in the main circuit 31 have larger contacts than the limit switches 224 and 226 provided in the operation circuit 321 because the current flowing through the main circuit 31 is larger than the current flowing through the operation circuit 321.

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

[0052] After the connection in the positive phase is detected and the contact point 41 is closed, when the downward operation switch 53 is operated, the coil 234 that constitutes the downward electromagnetic contactor 232 of the electromagnetic contactor 23 is energized, and the contact point 233 of the downward electromagnetic contactor 232 provided in the main circuit 31 is closed. As a result, the motor 1 is energized via the limit switch 225 of the downward winding prevention device 222A. At this time, the electromagnetic brake 3 is also energized, the electromagnetic brake 3 is released, and the motor 1 is driven in the 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 winding prevention device 221A open, and the energization of the motor 1 is stopped. Also, 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 winding prevention device 222A open, and the energization of the motor 1 is stopped.

[0054] For the comparative example that performs the above configuration and operation, the control device 10 of the present embodiment does not include the reverse phase prevention device 40 and the contact point 41, but includes the power supply on / off electromagnetic contactor 21. Then, when the input operation switch 50, which is the first switch, is operated and the coil 212 is energized, the main contact point 210 and the auxiliary contact point 211 are closed, and the operation circuit 32 forms a self-holding circuit. When the winding prevention device 22 operates during the driving of the motor 1, the self-holding circuit formed by the operation circuit 32 is released, the main contact point 210 and the auxiliary contact point 211 open, and the energization of the motor 1 is stopped.

[0055] As a result, since the reverse-phase prevention device 40 is not provided, when it is connected in reverse phase, the electric motor 1 is driven, but overwinding and underwinding are suppressed by the overwind prevention device 22. For this reason, without providing the reverse-phase prevention device 40, failures of the hoist 100, dropping of the suspended load, etc. are suppressed, and safety is ensured.

[0056] Also, although the structure of the reverse-phase prevention device 40 is complex, it is an unnecessary configuration after the reverse connection of the hoist 100 is corrected to a normal connection or when the hoist 100 has been connected in normal phase since the installation. Since the control device 10 of the present embodiment does not include the reverse-phase prevention device 40 that becomes unnecessary when connected in normal phase, the manufacture of the control device 10 and the hoist 100 including the control device 10 can be simplified, contributing to reduction of the manufacturing cost.

[0057] Also, the overwind prevention device 22 of the present 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 supply on-off electromagnetic contactor 21 opens, stopping the power supply to the electric motor 1. Therefore, it is not necessary to provide the limit switch constituting the overwind prevention device 22 in the main circuit 31. For this reason, unlike the case of being provided in the main circuit 31 like the limit switch of the comparative example, measures such as increasing the size of the limit switch of the overwind prevention device 22 according to the current supplied to the electric motor 1 are not necessary.

[0058] Also, when the overwind prevention device 22 is inoperative, the auxiliary contact 211 of the power supply on-off electromagnetic contactor 21 closes, and the operation circuit 32 forms a self-holding circuit. For this reason, by the user pressing the upward operation switch 52 or the downward operation switch 53, the load hook 8 can be wound up or down, and the function as the hoist 100 can be exhibited.

[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 electric 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 electric 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] When the upward operation switch 52 or the downward operation switch 53 is operated while the input operation switch 50 is being pressed, and after the motor 1 is driven and the overwind prevention device 22 becomes inoperative, the auxiliary contact 211 closes and the operation circuit 32 forms a self-holding circuit. As a result, the hoist 100 can be made capable of being wound up or down again according to the operation of the user.

[0064] The present invention is not limited to the content described in the above embodiments. Other aspects conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. For example, the hoist is not limited to an electric chain block, and may be a hoist in which a wire as a load rope is wound around a drum as a rotating body.

Explanation of Reference Numerals

[0065] 1 Motor, 5 Operation input device, 8 Load hook, 10 Control device, 21 Power supply on / off electromagnetic contactor, 22 Overwind prevention device, 31 Main circuit, 32 Operation circuit, 50 Input operation switch, 51 Cut operation switch, 52 Upward operation switch, 53 Downward operation switch, 100 Hoist, 101 Hoist body, 102 Power supply, 210 Main contact, 211 Auxiliary contact, 212 Coil, 221 Upward overwind prevention device, 222 Downward overwind prevention device

Claims

1. a first circuit to which a power source and an electric motor are connected; a second circuit to which an operation input device for receiving an operation for instructing the operation of the electric motor is connected; a first contact provided in the first circuit for connecting or disconnecting 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 for connecting or disconnecting the operation input device to / from the second circuit by opening and closing, and a power supply on / off electromagnetic contactor for enabling the electric motor to be driven in response to an operation of a first switch of the operation input device; a winding prevention device connected to the second circuit for stopping energization of the electric motor when a load hook for hooking a load reaches an upper limit position or a lower limit position by driving of the electric 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; a control device for a hoist, wherein when the winding prevention device operates during driving of the electric motor, the self-holding circuit formed by the second circuit is released, the first contact and the second contact are opened, and energization of the electric motor is stopped.

2. In the control device for a hoist according to Claim 1, the first switch is a self-return type switch, when the winding prevention device is not operating, when the first switch is operated, the state in which the second contact is closed is maintained, after the winding prevention device operates during driving of the electric motor, the second contact is closed only while the first switch is being operated, a control device for a hoist.

3. In the control device for a hoist according to Claim 2, the winding prevention device has 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, the first limit switch, the second limit switch, and the second contact are connected in series in the second circuit, a control device for a hoist.

4. In the control device for a hoist according to Claim 3, the operation input device has a second switch for instructing driving of the electric motor so that the load hook moves upward and a third switch for instructing driving of the electric motor so that the load hook moves downward. After the first limit switch is opened, if the third switch is operated while the first switch is in an operated state, the motor is driven in a direction to move the load hook downward, A control device for a hoist, wherein after the second limit switch is opened, if the second switch is operated while the first switch is in an operated state, the motor is driven in a direction to move the load hook upward.

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

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, 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 for connecting or disconnecting 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 for connecting or disconnecting the operation input device from the second circuit by opening and closing. A power-on / off electromagnetic contactor that enables the motor to be driven in response to an operation of a first switch included in the operation input device, An anti-overwinding device connected to the second circuit and stopping energization of the motor when a load hook that hooks a suspended 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 close, and the second circuit forms a self-holding circuit that maintains an energized state, A hoist in which when the anti-overwinding 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 open, and the energization of the motor is stopped.

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