JPH051785U - Overwound Limit Switch Mechanism in Electric Hoist - Google Patents

Abstract

(57) [Summary] [Purpose] It is an object of the present invention to provide an overwinding limit switch mechanism for an electric hoist that can easily perform recovery work while ensuring sufficient safety. [Structure] The working limit switch 10 that operates near the hoisting top dead center of the hoisting motor 4 to stop the hoisting motor 4 and the working limit switch 10 that accompanies the hoisting operation operate to shut off the power supply. In addition to the emergency limit switch 11 for stopping the entire electric hoist 1 including the hoisting motor 4, it operates after the operation of the service limit switch 10 associated with the hoisting operation and before the operation of the emergency limit switch 11. Another emergency limit switch 16 for stopping the hoisting motor 4 is provided, and the normal limit switch 1
This is to improve the workability of the recovery work when 0 does not operate due to a failure or the like.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an overwinding limit switch mechanism for an electric hoist and is useful as a safety device for an electric hoist.

[0002]

[Prior Art]

 As shown in FIG. 3, an electric hoist 1 is driven by a traverse motor 2 to travel along a rail 3, and a hoisting motor 4 is driven to wind and unwind a wire rope 5 to lift and lower a hook 6. Is. Such control of traveling and lifting is performed by pressing each operation switch of the operation push button 9 connected to the hoist body 8 via the cable 7. Further, the hoist body 8 is provided with a control box for accommodating each component of the control sequence circuit.

Various types of sequence circuits for the electric hoist 1 have been proposed in the past. As one of them, in addition to the normal limit switch that operates near the winding-up dead center of the winding operation, Some are equipped with an emergency limit switch. The normal limit switch and the emergency limit switch are both for the purpose of preventing overwinding performed in the winding operation, but the normal limit switch operates at a relatively early point in time associated with the winding operation. While the current supply to the hoisting motor 4 is cut off, the emergency limit switch operates at a relatively late time associated with the hoisting operation, cutting off the power supply of the electric hoist 1 and turning on the electric motor including the hoisting motor 4. The entire operation of the hoist 1 is stopped.

FIG. 4 is a structural diagram showing a conventional overwinding limit switch mechanism having two types of limit switches, a normal type and an emergency type, housed in a control box as described above. As shown in the figure, the service limit switch 10 and the emergency limit switch 11 are housed and fixed in the control box 12, and the working limit switch cam 13 and the emergency limit switch lever, which are the operating members. It is operated by 14.

More specifically, the service limit switch cam 13 and the emergency limit switch lever 14 are fixed to a rod 15 which is supported in the control box 12 so as to be vertically movable. The rod 15 ascends (at the time of winding) and descends (at the time of winding) near the top dead center via a lever arm (not shown) connected to its lower end. Thus, with the lowering of the rod 15 during the hoisting operation, the service limit switch cam 13 is first formed at the lower part of the service limit switch cam 13 and the diameter of the service limit switch cam 13 is gradually reduced downward. By making contact with the actuator 10a, the actuator 10a is rotated counterclockwise to operate the service limit switch 10.

Normally, the operation of the service limit switch 10 deactivates an electromagnetic relay (not shown) that supplies a current to the hoisting motor 4, and its contact is opened to interrupt the supply of the current to the hoisting motor 4. To be done. As a result, the hoisting motor 4 is stopped, and at that time, the hoisting operation is stopped.

On the other hand, if the rod 15 is further lowered for some reason, the tip of the emergency limit switch lever 14 pushes down the actuator 11a of the emergency limit switch 11 to move the emergency limit switch 11 into position. To operate. As a result, the power source of the electric hoist 1 is cut off, and the whole operation of the electric hoist 1 including the hoisting motor 4 is stopped.

As described above, when the hoisting motor 4 is stopped, the stopped state of the hoisting motor 4 is maintained by the braking force of a hoisting brake (not shown) that is integrally incorporated in the hoisting motor 4. The safety of the work is ensured by preventing the hanging luggage from falling.

[0009]

In the overwound limit switch mechanism according to the prior art having the above-mentioned configuration, when the normal limit switch 10 fails to operate due to a failure or the like, the emergency limit switch 11 Works. This is good from a safety point of view, but in this case the power supply is cut off, so there is the problem that it takes time to recover, especially when luggage is suspended.

That is, when the emergency limit switch 11 operates, the operation push button 9 cannot be operated to provide any effective treatment for restoration, and therefore, for restoration, an operator must remove the hoist body 8 from the operator. It is necessary to ascend to the place and manually release the hoisting brake to release the hoisting motor 4 from braking.

By the way, since the service limit switch 10 is frequently used, it easily breaks down, and when the hoisting speed is high, the emergency limit switch 11 may be operated by inertia.

The present invention has been made in view of the above-described conventional art, and an object thereof is to provide an overwinding limit switch mechanism in an electric hoist that can easily perform recovery work while ensuring sufficient safety.

[0013]

[Means for Solving the Problems]

 The configuration of the present invention that achieves the above object is

[0014] The working limit switch and the first emergency limit switch that cut off the supply of current to the hoisting motor to stop the hoisting motions associated with the driving of the hoisting motor, and the power source of the electric hoist are cut off. Second emergency limit switch for stopping the overall operation of the electric hoist including the hoisting motor, a rod that moves up and down in the axial direction in association with the driving of the hoisting motor, and a rod integrally with the rod. It is fixed to this rod so that it can move up and down, and during the hoisting operation by the drive of the hoisting motor, it moves up and down integrally with the first operating member that operates the service limit switch at the specified operating point. It is fixed to the rod, and during the hoisting operation by the drive of the hoisting motor, the first emergency limit switch is activated after passing the operating point of the service limit switch. The second operating member to be moved is fixed to this rod so as to move up and down integrally with the rod, and during the hoisting operation by the drive of the hoisting motor, the second operating member is passed after the operating point of the first emergency limit switch. And a third operating member for operating the emergency limit switch.

[0015]

[Action]

 According to the present invention having the above-mentioned configuration, even if the service limit switch does not operate due to a failure or the like, the operation of the first emergency limit switch can prevent overwinding. Further, in this case, since the supply of current to the hoisting motor is merely cut off, the normal operating condition can be easily restored by operating the operation push button of the electric hoist.

[0016]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the same parts as those of the prior art are denoted by the same reference numerals, and overlapping description will be omitted.

As shown in FIG. 1, the overwound limit switch mechanism according to the present embodiment is an emergency limit switch 16 as a first emergency limit switch and a second operating member for operating the emergency limit switch 16. The cam 17 for the emergency limit switch is added. Further, in the present embodiment, the first operating member is constituted by the common limit switch cam 13, the third operating member is similarly constituted by the emergency limit switch lever 14, and the second emergency limit switch is constituted by the emergency limit switch. Each is composed of a switch 11.

The emergency limit switch 16 shuts off the supply of current to the hoisting motor 4 by its operation similarly to the normal limit switch 10, and is arranged in the control box 12 below the normal limit switch 10. It is fixed. The emergency limit switch cam 17 has the same shape as the normal limit switch cam 13, that is, a cam having a tapered surface 17a. The emergency limit switch cam 17 is provided in the rod 15 in correspondence with the position of the emergency limit switch 16. It is fixed below. Thus, with the lowering of the rod 15, the normal limit switch 10, the emergency limit switch 16 and the emergency limit switch 11 are sequentially operated.

FIG. 2 is a sequence circuit diagram of an electric hoist having the overwinding limit switch mechanism according to the above embodiment. As shown in the figure, the service limit switch 10 and the emergency limit switch 16 are connected in series to deactivate the electromagnetic relay M C1 by their respective operations. The deenergization of the electromagnetic relay MC1 opens the a contacts mc1-1 and mc1-2, the operation of the hoisting motor 4 is stopped, and the braking force of the hoisting brake 18 acts on the hoisting motor 4. It keeps the stopped state.

On the other hand, the electromagnetic relay MC1 is urged by pressing the raising switch 9a of the operation push button 9 under the condition that the normal limit switch 10 and the emergency limit switches 11 and 16 are not operated, and its contact points mc1-1 and mc1-1. Close mc1-2. As a result, the braking force of the hoisting brake 18 is released, and the hoisting motor 4 performs the hoisting operation. Further, the electromagnetic relay MC2 is urged by pressing the lowering switch 9b of the operation push button 9 on condition that the emergency limit switch 11 is not operated, and closes its contacts mc2-1 and mc2-2. As a result, the braking force of the hoisting brake 18 is released, and the hoisting motor 4 performs the hoisting operation.

In the figure, 9 is a three-phase power source, and 20 is a rectifier.

In the above embodiment, when the a-contacts mc1-1 and mc1-2 are closed by the bias of the electromagnetic relay MC1 and the hoisting motor 4 performs the hoisting operation, the vicinity of the hoisting top dead center is reached. The service limit switch cam 13 operates the service limit switch 10 as the rod 15 is lowered. As a result, the electromagnetic relay MC1 is deenergized to open the a-contacts mc1-1 and mc1-2, and the hoisting motor 4 is stopped and held in that state.

On the other hand, when the service limit switch 10 does not operate due to a failure or the like, and when the rod 15 further descends due to inertia, the emergency limit switch 16 operates next. As a result, a state similar to that when the above-mentioned regular limit switch 10 operates is obtained.

As described above, when the normal limit switch 10 and the emergency limit switch 16 are operated, the lowering switch 9b is operated to cause the hoisting motor 4 to perform the lowering operation. Rises to reset the emergency limit switch 16 and the service limit switch 10. Thus, the electric hoist 1 can be put into a normal use state.

It should be noted that when the emergency limit switch 16 operates, it is easy to configure the display means to indicate this, and in this case, there is an effect that an abnormal state can be easily notified. ..

[0026]

[Effect of the device]

 According to the present invention, as described in detail with reference to the above embodiments, the winding operation is stopped by the first emergency limit switch even if the service limit switch fails, which is effective. Not only is it possible to prevent overwinding, but it is also possible to easily restore the normal use of the electric hoist. Therefore, the predetermined work by the electric hoist can be efficiently performed.

[Brief description of drawings]

FIG. 1 is a structural diagram showing an overwind limit switch mechanism according to an embodiment of the present invention.

FIG. 2 is a sequence circuit diagram of an electric hoist having the overwinding limit switch mechanism according to the embodiment.

FIG. 3 is an overall structural diagram showing an example of an electric hoist.

FIG. 4 is a structural diagram showing a conventional overwinding limit switch mechanism applied to an electric hoist.

[Explanation of symbols]

 1 Electric Hoist 4 Hoisting Motor 10 Service Limit Switch 11 Emergency Limit Switch 13 Service Limit Switch Cam 14 Service Limit Switch Lever 15 Rod 16 Service Limit Switch 17 Service Limit Switch Cam 19 Three-phase Power Supply

Claims (1)

[Claims for utility model registration] [Claim 1] A working limit switch and a first emergency limit for cutting off the supply of electric current to the hoisting motor and stopping the hoisting operation accompanying the driving of the hoisting motor. A switch, a second emergency limit switch that shuts off the electric hoist's power supply to stop the entire operation of the electric hoist including the hoisting motor, and moves up and down along its axial direction as the hoisting motor is driven. And a first operating member that is fixed to the rod so as to move up and down integrally with the rod, and that operates the service limit switch at a predetermined operating point during the hoisting operation by driving the hoisting motor,
A second operating member that is fixed to the rod so as to move up and down integrally with the rod and that operates the first emergency limit switch after passing through the operating point of the service limit switch during the winding operation by driving the hoisting motor. And is fixed to this rod so as to move up and down together with the rod, and during the hoisting operation by the drive of the hoisting motor, the second emergency limit switch is operated after passing the operating point of the first emergency limit switch. An over-wound limit switch mechanism in an electric hoist, comprising: