JPH09104591A - Overwind preventing device for motor-driven hoist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform miniaturization of a device while ensuring performance as the overwind preventing device, improve general purpose usability by utilizing an article on the market, and improve maintainability and reduce cost when a part is replaced. SOLUTION: A shaft 4 is inserted by utilizing a square hole in the central part of a lever 3, and a spring for returning back to a neutral position is provided in the inside of the shaft 4 and a drum with groove 2. A switch on the market is used as an overwind preventing switch, the switch is provided in the periphery of the drum with groove 2, and a tip end part of the lever 3 of the switch is set up in the groove. In a shape of a groove part of the drum with groove 2, first a contact of the switch for an operation circuit is interrupted, next a contact of the switch for a power circuit is interrupted in accordance with a rolling angle amount of the shaft 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric hoist,
In particular, it relates to an overwinding prevention device at the time of upper and lower limits of an electric hoist.

[0002]

2. Description of the Related Art Conventionally, in an electric hoist such as an electric chain block, a push button switch hung from a hoisting body through a cable is operated to control an electromagnetic contactor to rotate the electric motor to reduce the speed. Winding the chain through the section
It is being unwound. In addition, an overwinding prevention device to prevent overwinding at the upper and lower limits of the electric hoisting machine is equipped with a lever at the chain lifting part of the hoisting body, and when the chain reaches the upper limit or the lower limit, a stopper or The lifting device pushes up to rotate the shaft in the center of the lever, and the integrated switch connected to the shaft is operated to shut off the operating circuit and operating circuit, stopping the hoisting or unwinding operation. There is. Similarly, it has a lever and a shaft in the center part, a steel ball integrated type switch part is provided at the chain entrance and exit part of the chain elevating part, the steel ball is pushed in by the turning angle of the lever, and the switch opening and closing operation is performed. There are methods such as control. Here, the overwinding prevention device may be of a double cutoff type that first cuts off the operation circuit and surely cuts off the power circuit by increasing the turning amount even if the operation circuit is not cut off. Desirably, the overwinding prevention device needs to be a mechanical type that can reliably break the circuit also in terms of reliability. In addition, the operation circuit was cut off so that the hoisting operation was possible when the hoisting operation was stopped, and conversely, the hoisting operation was possible when the hoisting operation was stopped. These controls will be described below with reference to FIGS. 4 to 8. First, when the hoisting command button 10A of the push button switch 10 is pressed, electric power is supplied from the hoisting operation circuit switch 1A to the hoisting coil 13A of the electromagnetic contactor 13, and the hoisting contact 13 of the electromagnetic contactor 13 is supplied.
C is closed, power is supplied to the electric motor 11 and the brake 12 via the power circuit switch 1C, the brake 12 is opened, and the winding operation is started. When the operation is performed up to the upper limit in this state, the lower hanger 18 first pushes up the chain guide 5 and the lever 3, and the turning angle of the lever 3 causes the shaft 4 in the central portion of the lever 3 to turn. By this turning operation, the cam inside the switch portion 1 integrated with the shaft 4 is turned, the hoisting operation circuit switch 1A is opened, and the power supply to the hoisting coil 13A of the electromagnetic contactor 13 is cut off. As a result, the hoisting contact 13C of the electromagnetic contactor 13 is opened, power supply to the electric motor 11 and the brake 12 is cut off, and the hoisting operation is stopped. Here, if it should not stop due to a failure or the like, the amount of turning angle of the lever 3 and the shaft 4 increases, and the power circuit is surely shut off by opening the power circuit switch 1C. Similarly,
In the case of the unwinding operation, the unwinding command button 10B is pressed to supply power to the unwinding coil 13B from the unwinding operation circuit switch 1B, the unwinding contact 13D is closed, and the electric motor 11 and the power circuit switch 1C are connected. Electric power is supplied to the brake 12 to start the lowering operation. If it does not stop, the turning angle of the lever 3 and the shaft 4 increases, and the power circuit is cut off by opening the power circuit switch 1C. Similarly in the case shown in FIG. 6, the steel ball 8 is pushed by the turning angle of the lever 3, and the same effect as described above is obtained by the turning angle amount and the pushing depth.

[0003]

Even a general electric chain block of the prior art is currently used most often, so there is no particular problem. However, in the conventional overwinding prevention device, the switch part is not provided. Since it is an integrated structure that is integrally molded, it must be replaced with a unit when parts are replaced,
The device was large in size and was not versatile. In addition, it is necessary to reduce the price as well.

[0004]

The lever is the same as the conventional one, and a shaft is inserted through a square hole in the central portion of the lever, and a spring for returning to a neutral position is provided inside the shaft and the grooved drum. A commercially available switch is used as the switch for preventing overwinding, a switch is provided around the grooved drum, and the lever tip of this switch is installed in the groove. In addition, the shape of the groove part of the grooved drum is configured so that the contact of the micro switch for the operation circuit is interrupted first, and then the contact of the switch for the power circuit is interrupted, depending on the turning amount of the lever and shaft. To do.

According to the present invention described in the above-mentioned means, the size of the device can be reduced while ensuring the performance as the overwinding preventing device, and further, the versatility can be improved by using a commercially available product, and the parts can be replaced. It is possible to improve maintainability and reduce costs.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Taking the case where the present invention is applied to an electric chain block as an example, a description will be given based on an embodiment shown in the drawings. FIG. 1 is a structural explanatory view according to the present invention, and FIG. 2 is a neutral according to the present invention. FIG. 3 is a structural diagram of a position return spring portion, FIG. 3 is an operation explanatory diagram according to the present invention, FIG. 4 is an external view of an electric chain block, and FIG.
Is an operation explanatory view of the lever portion, and FIG. 8 is an electric circuit diagram of the electric chain block.

A method of operation and a circuit configuration will be described with reference to FIGS. 4, 9 is a cable for transmitting signals to the electric chain block, 10 is a push button switch for hoisting and lowering operations, 10A and 10B are hoisting command buttons, hoisting command buttons,
11 is an electric motor, 12 is a brake, 13 is an electromagnetic contactor, 1
3A to 13D are hoisting and lowering coils of the electromagnetic contactor 13, hoisting and lowering contacts, 14 is a transformer, 15 is a speed reduction unit for decelerating the rotation of the electric motor 11, and 16 is an electromagnetic contactor 13 or the like. The control unit, 17 is a chain, and 18 is a hanging device that is connected to the chain 17 to wind and lower the load.

In the operation of the electric chain block, in the case of a hoisting operation, when the hoisting command button 10A is pushed, power is supplied to the hoisting coil 13A via the hoisting operation circuit switch 1A, and the hoisting contact is closed, and the power circuit is closed. The power circuit of the electric motor 11 and the brake 12 is configured from the switch 1C for electric power, and the brake 12 is opened at the same time when the electric power is supplied to the electric motor 11,
The electric motor 11 starts rotating. The rotation of the electric motor 11 is reduced to a predetermined rotation speed by the reduction unit 16, and the chain 17,
The lower suspension 18 is rolled up. The same applies to the case of the lowering operation, and the chain 1 is pressed by pressing the lowering command button 10B.
7. Lower the lower hanging device 18. In addition, if the upper or lower limit is reached during the hoisting or lowering operation, there is a risk of dropping the luggage or damage to the equipment, so it is necessary to stop the operation when it reaches the upper or lower limit for emergency and prevent overwinding. .

The overwinding prevention device will be described below with reference to FIGS. 1, 2, 3 and 7. 1 is an overwinding prevention switch using a commercially available switch, 1A to 1C are hoisting operation circuit switches, lowering operation circuit switches, power circuit switches, 2 is for opening and closing the overwinding prevention switch 1. Grooved drum, 3 is a lever for turning at upper and lower limits of winding up / down, 4 is a shaft for transmitting a turning angle of the lever 3 to the grooved drum 2, 5 is a chain guide, 6 is a grooved drum 2 A mounting screw for connecting the shaft 4 and the shaft 4 is a neutral position return spring for returning the shaft 4 and the lever 3 from the grooved drum 2 to the neutral position at the time of operations other than the upper and lower limits. When the hoisting or hoisting operation is performed and the upper limit or the lower limit is reached, when the upper limit is reached, the lower hanger 18 is pushed up, and when the lower limit is reached, the chain guide 5 is pushed up by the stopper provided at the chain end portion, and the lever 3 is accordingly pushed by the shaft 4. A turning angle is performed around the square hole. This turning amount is transmitted via the shaft 4 to the grooved drum 2 connected by the mounting screw 6, and the overwinding prevention switch 1 is shut off according to the turning amount and turning direction to stop the operation. Here, the operation shown in FIG. 3 will be described. Groove drum 2 for hoisting operation
Turns counterclockwise, the lever tip of the hoisting operation circuit switch 1A is pushed by the inclination of, and the b contact of the hoisting operation circuit switch 1A is cut off. At this time, the lowering operation circuit switch 1B is not cut off to enable the lowering operation. Even if the overwinding prevention device is not cut off due to a contact failure or the like due to excessive use, the pair of inclinations of the power circuit switch 1C is increased due to the increase in the turning amount of the grooved drum 2. The b contact is surely cut off to stop the power supply to the electric motor 11 and the brake 12. In the case of the lowering operation as well, the lowering operation circuit switch 1B and the power circuit switch 1C are interrupted at any time by a pair of inclinations depending on the amount of clockwise rotation of the grooved drum 2. Further, when the overwinding prevention device operates, it is necessary to enable the following operation. Therefore, as shown in FIG. 2, a neutral position return spring 7 is provided on the outer circumference of the shaft 4 inside the grooved drum 2 to wind it up.・ The spring force returns to the neutral position regardless of the direction of winding.

[0010]

According to the present invention, the following effects can be obtained while ensuring the performance as a conventional overwinding prevention device.

That is, a commercially available switch and a grooved drum are used, and a neutral position return spring is installed inside the drum, so that the apparatus can be downsized, and the maintainability at the time of parts replacement is improved and the cost is reduced. Achieve commercialization aimed at commercialization.

[Brief description of the drawings]

1 is an illustration of a structure according to the present invention.

FIG. 2 is an explanatory view of a neutral position return spring portion according to the present invention.

FIG. 3 is an explanatory diagram of an operation according to the present invention.

FIG. 4 is a side view of the electric chain block.

FIG. 5 is a side view of a conventional overwinding prevention device.

FIG. 6 is a side view of a conventional overwinding prevention device.

FIG. 7 is an explanatory diagram of a lever operation.

FIG. 8 is an electric circuit diagram of the electric chain block.

[Explanation of symbols]

1 ... Overwinding prevention switch, 1A ... Hoisting operation switch,
1B ... Unwinding operation switch, 1C ... Power circuit switch, 2 ... Grooved drum, 3 ... Lever, 4 ... Shaft, 5
… Chain guide, 6… Mounting screws.

Claims (3)

[Claims] 1. An upper / lower limit overwinding prevention device for an electric hoist, wherein displacement of overwinding operation is detected as a turning angle amount by a cylindrical member via a shaft, and a groove provided in the cylindrical member is used. An electric hoist having an overwinding prevention device, characterized in that a switch provided on the outer periphery thereof is configured to be operated. 2. The overwinding prevention device according to claim 1, wherein an elastic body for maintaining a neutral position other than the upper and lower limits is provided inside the cylindrical member. 3. The overwinding prevention device according to claim 1, wherein the groove of the cylindrical member is formed so as to operate the switch in multiple stages according to the turning angle.