JPH09255288A - Device for preventing overwinding of electric hoist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damaging caused by clashing between a hoist main body and a hook device, the damaging of the guide plate of a main switch or a tension rod and the deformation of an overwinding preventing lever. SOLUTION: An overwinding preventing lever 11 and the supporting arm section 12a of a press lever 12 for actuating a microswitch 2 following the operation of the lever 11 are pivotally attached to a first supporting shaft 10 between two supporting plates 9 provided in the lower part of a hoist wiring box 1 so as to be rotated. Further, the supporting arm section 16a of a rotary lever 16 having linear and arc-shaped slits in its side part is pivotally attached to a second supporting shaft 15 between the supporting plates 9 so as to be rotated. A rod pin 19 provided in the base part of the overwinding preventing lever 11 is engaged with the slit 18 of the rotary lever 16 so as to be slid, a tension rod 8 for opening/closing the contact point of the main switch 3 is inserted into the hole of the inclined flat plate section 16b of the rotary lever 16 and a specified interval (d) is maintained between the lower end part of the tension rod 8 and the rotary lever 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an overwinding prevention device for an electric hoist.

[0002]

2. Description of the Related Art Conventionally, various overwinding preventive devices have been devised and put into practical use for electric hoists in order to prevent collision between the hook device and the hoist body due to overwinding and cutting of the wire rope. Among them, the micro switch for operating the electromagnetic switch of the hoisting motor that operates by the first step rotation of the overwinding prevention lever and the second step that operates as the fail-safe mechanism by the second step rotation. Japanese Utility Model Publication No. 56-36874 discloses an overwinding preventive device including a hoisting motor independent of the contacts of an electromagnetic switch and a main switch provided between a power source.

The one disclosed in this publication will be briefly described with reference to FIG. That is, as shown in the drawing, a hoisting electric motor (not shown) provided in the hoist body 51 of the electric hoist 50 is driven, and a hook device 56 including a hook 53, a pulley 54, and a pulley case 55 via a wire rope 52. When the pulley 54 of the hook device 56 pushes the flat U-shaped over-winding prevention lever 58 of the over-winding prevention device 57, the micro switch 59 is activated by the swing of the over-winding prevention lever 58, that is, The pressing force of the micro switch 59 is released, the exciting coil (not shown) of the electromagnetic switch (not shown) in the wiring box 60 is demagnetized, the hoisting motor is stopped, and the hook device 56 is stopped at a fixed position.

However, when the contacts of the micro switch 59 and the electromagnetic switch become electrically or mechanically inoperable due to welding or the like, the function of the micro switch 59 is impaired and the hook device 56 is further raised. As shown in FIG. 12, the overwinding prevention lever 58 is swung in the arrow direction.

Due to this swinging, the rod 61 provided on the overwinding prevention lever 58 moves downward and comes into contact with the locking nut 63 provided at the lower end of the tension rod 62 which penetrates the rod 61, and compresses the tension rod 62. Move it downwards against the spring 64, and
The lower contact 66 is displaced downward via 65. As a result, the lower contact 66 is separated from the upper contact 67, the main switch 68 is opened, the hoisting motor is stopped, and the lifting of the hook device 56 is stopped.

[0006]

In the prior art described above, when the overwinding prevention lever is rotated in the first step in normal use, the microswitch operates to demagnetize the exciting coil of the electromagnetic switch. Then, the rotation of the hoisting motor is stopped. In the unlikely event that the contacts of the electromagnetic switch of the hoisting electric motor are welded or mechanically broken, and the contacts cannot be opened at all, the main switch is provided completely separately from the electromagnetic switch series. Since the power supply circuit of the hoisting motor can be surely cut off by the opening operation of (1), the tentative function was achieved as the overwinding prevention device. However, the following problems still remain in this overwinding prevention device.

When the electric hoist is installed, the boxed electric hoist is usually lifted by an upper chain block or the like, unpacked, and attached to the crane girder. At that time, an extension portion of the overwinding prevention lever that engages with the hook device may be erroneously brought into contact with a packaging base or the like, or an external force may be applied to the overwinding prevention lever to rotate the lever more than a prescribed amount.

Further, since the electric hoist and the crane make a traveling motion, the hook device is liable to shake in the unloaded state, and when the hook device is hoisted at the uppermost position, the hook device that hits the over-winding prevention lever is The contact position may be different, and the overwinding prevention lever may be rotated more than the specified amount. In such a case, there have been problems such as damage to a part of the device, damage to the guide plate and the pull rod of the main switch, and deformation of the overwinding prevention lever.

The present invention has been made in order to solve the above-mentioned conventional problems. The microswitch is operated by the first rotation of the overwinding prevention lever, and the main switch is operated by the second rotation of the lever. The switch is operated with a time delay, and when the lever is rotated more than a specified amount, the rotation is absorbed to prevent damage due to the collision between the hoist body and the hook device, and the main switch guide plate. It is an object of the present invention to provide an over-winding prevention device for an electric hoist that avoids damage to the pulling rod and the pull rod and eliminates deformation of the over-winding prevention lever.

[0010]

According to the first aspect of the present invention,
Two support plates are provided below the hoist wiring box containing a micro switch for opening and closing the electromagnetic switch of the hoisting motor and a main switch for connecting and disconnecting the power supply circuit of the hoisting motor, and between the support plates. A first support shaft pivotally mounts an overwinding prevention lever and a support arm part of a push lever which follows the lever and actuates the micro switch, and a second support shaft is provided between the support plates. At the side, a supporting arm portion of a rotary lever having a substantially U-shaped plane having a linear elongated hole portion and an arc-shaped elongated hole portion continuous to the side portion is rotatably pivoted, and the excessive winding is prevented. The rod pin provided at the base end of the lever is slidably engaged with the elongated hole of the rotary lever, and the pull rod for opening and closing the contact of the main switch is attached to the oblique flat plate portion of the rotary lever. Insert it through the hole that was drilled and pull it At the lower end of the head, it is characterized in that by maintaining a predetermined distance between the pivot lever.

As described above, the two sheets of the hoist wiring box, which face each other and are opposed to each other, accommodate the micro switch for opening and closing the electromagnetic switch of the hoisting motor and the main switch for connecting and disconnecting the power supply circuit of the hoisting motor. Between the support plates of
An over-winding prevention lever and a base end portion of a support arm portion of a push lever which follows the first rotation shaft orthogonal to the support plate and provided on one side of the support plate are pivotally attached to the first support shaft. Then, in a normal state, the tip end side of the overwinding prevention lever is lowered by the self-weight of the overwinding prevention lever, and the push lever is urged upward at the base end side to operate the micro switch.

Further, the second supporting shaft, which is orthogonal to the supporting plate and is provided on the other side of the supporting plate, has a linear elongated hole portion and an arcuate elongated hole portion continuous with the linear elongated hole portion on the side support arm portion. A pivoting lever having a substantially U-shape in plan view is rotatably pivotally mounted, and a rod pin provided on a support plate of the overwinding prevention lever is slidably mounted on the oblong hole of the pivoting lever. A pulling rod that is movably engaged and that inserts a tension rod that opens and closes a contact of the main switch into a hole formed in the oblique flat plate portion of the rotating lever, and a locking nut provided at a lower end portion of the pulling rod. , A predetermined distance is maintained between the rotation lever and the overwinding prevention lever when it comes into contact with the hook device and rotates upward by the first step, the push lever has its own weight and the micro switch. Moves downward by the built-in spring of the micro switch It is operated by demagnetizing the excitation coil of the electromagnetic switch and stops the rotation of the hoisting motor.

And by any chance, welding of the contacts of the electromagnetic switch,
If the contacts cannot be opened at all due to a mechanical failure, the second rotation of the overwinding prevention lever pushes down the rotation lever via the rod pin. By forcibly pulling down the pull rod of the main switch, which is provided separately, the power supply circuit of the hoisting motor is surely cut off.

Further, when the overwinding prevention lever is forcedly rotated by an external force or a load shake more than a predetermined value, only the rod pin is moved in the arc-shaped elongated hole portion provided in the rotation lever to absorb the rotation. That is, only the overwinding prevention lever is rotated to avoid the rotation of the rotation lever. This prevents external force from being applied to the pull rod.

According to a second aspect of the present invention, between the two support plates, a push lever for operating the microswitch,
The rotary lever for operating the main switch and the lower end portion of the pull rod are housed so as not to be exposed.

As described above, the push lever for actuating the micro switch, the rotating lever for actuating the main switch, and the lower end portion of the pull rod are housed between the two support plates so as not to be exposed, and the hoist wiring is provided. Even if the packing base accidentally contacts the bottom of the box, it is received by two support plates to ensure protection and prevent damage.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention understood from the description of claim 1, as shown in FIG. 3, a micro switch 2 for opening and closing an electromagnetic switch of a hoisting motor and a power supply circuit of the hoisting motor are provided. Two support plates 9 are provided below the hoist wiring box 1 which houses the main switch 3 to be connected and disconnected.
An overwinding prevention lever 11 and a support arm portion 12a of a push lever 12 that drives the microswitch 2 by following the overwinding prevention lever 11 are pivotally attached to the first support shaft 10 between the support plates 9.

Further, the second support shaft 15 between the support plates 9
Further, the supporting arm portion 16a of the rotary lever 16 having a substantially U-shaped plane and having the linear elongated hole portion 18a and the arcuate elongated hole portion 18b continuous with the linear elongated hole portion 18a is rotatably pivoted. A rod pin 19 provided at the base of the overwinding prevention lever 11 is slidably engaged with an elongated hole 18 of a rotating lever 16. The pull rod 8 for opening and closing the contact of the main switch 3 is inserted into the hole 21 formed in the oblique flat plate portion 16b of the turning lever 16, and the lower end portion of the pull rod 8 is provided between the pull lever 8 and the turning lever 16. The predetermined distance d is maintained.

In the present invention grasped from the description of claim 2, as shown in FIG. 3, between the two support plates 9,
The push lever 12 that operates the micro switch 2, the rotating lever 16 that operates the main switch 3, and the lower end portion of the pull rod 8 are housed so as not to be exposed.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In the figure, in a hoist wiring box (hereinafter referred to simply as a wiring box) 1 of an electric hoist, as shown in FIG. 3, a micro switch (limit switch) 2 for opening and closing an electromagnetic switch for a hoisting motor and a three-phase A main switch 3 for connecting and disconnecting the power source is provided for the two wires between the hoisting motor and the power source.

Further, in FIG. 4, reference numerals 3a and 3b are contacts of the main switch 3, respectively. Upper contact 3a
Is fixed to an upper plate 4 (see FIG. 3) integrated with the wiring box 1 through insulating means, and the lower contactor 3b is fitted to a pair of guide bars 5 and is vertically movable. 6 is also fixed via insulating means.

The guide plate 6 is biased upward by a compression spring 7 fitted on the guide rod 5. Therefore, the contact
3a and 3b always maintain a contact state. That is, the main switch 3 is closed.

A pull rod 8 is vertically provided at the center of the guide plate 6, and the pull rod 8 penetrates the wiring box 1 and extends downward.

On the other hand, in the lower part of the wiring box 1, two support plates 9 and 9 facing each other in the vertical direction are welded in parallel. As shown in FIGS. 2 to 4, on one side between the support plates 9 and 9, support plates 11a and 11a at the base of the overwinding prevention lever 11 and the support plates are provided on the first support shaft 10. Part 11a
The support arms 12a, 12a of the push lever 12 provided on the base end portion 11b side of the are pivotably attached.

The push lever 12 is formed in a substantially U-shape in plan view, and has a flat plate portion 12b and a supporting arm portion continuously provided therewith.
It is composed of 12a and 12a. In FIGS. 1 and 4, the reference numeral 13 is a pin for preventing the first support shaft 10 from coming off.

The tip side (the right side in FIG. 3) of the overwinding prevention lever 11 is a hook device of an electric hoist (reference numeral in FIG. 11).
56), and the base end portion 11b of the overwinding prevention lever 11 is in contact with the lower surface of the flat plate portion 12b of the push lever 12. The upper surface of the flat plate portion 12b of the push lever 12 is in contact with the micro switch 2.

Therefore, the push lever 12 is always urged upward by the weight of the overwinding prevention lever 11, and the contact of the micro switch 2 is closed. In addition, the rotation restriction of the push lever 12 in the upper direction is as shown in FIG.
Push lever to stopper 14 provided on the back of wiring box 1.
The flat plate portion 12b of the twelve is contacted, and the downward rotation restriction is performed by the contact of the support arm portion 12a of the push lever 12 with the upper surface of the second support shaft 15 described later.

Further, as shown in FIGS. 2 to 4, a second support shaft 15 is provided on the other side of the support plates 9 and 9, and the second support shaft 15 is supported on a side portion. A rotation lever 16 having an arm portion 16a is pivotally attached so as to be rotatable. The rotating lever 16 is formed in a substantially U-shape in a plane, and has an inclined flat plate portion 16
It is composed of b and supporting arm portions 16a, 16a provided continuously to the b portion. Incidentally, in FIG. 1 and FIG.
What is indicated by is a pine needle pin for preventing the second support shaft 15 from coming off.

As shown in FIG. 6, elongated holes 18 are provided on the side surfaces of the support arm portions 16a, 16a of the rotary lever 16, and the elongated holes 18 are a linear elongated hole portion 18a and a continuous elongated hole portion 18a. It is formed by the arc-shaped elongated hole portion 18b that is provided. The radius R of the arc-shaped elongated hole portion 18b is the
It is formed with a radius of rotation about the first support shaft 10 when the rotating lever 16 rotates downward until the contact of the main switch 3 is opened.

As shown in FIG. 5, a rod pin 19 provided near the base end portion 11b between the support plate portions 11a of the overwinding prevention lever 11 is slidably engaged with the elongated hole 18, as shown in FIG. .
In FIGS. 3 and 5, the reference numeral 20 is a pull-out prevention pine needle pin that also serves to position the rod pin 19.

Then, as shown in FIGS. 2 to 4, the pulling rod 8 for opening and closing the contact of the main switch 3 is inserted into the hole 21 formed in the oblique flat plate portion 16b of the rotating lever 16,
At the lower end of the pull rod 8, as shown in FIG. 3, a predetermined distance d is maintained between the pull rod 8 and the turning lever 16, and a locking nut 22 is fixed. The hole 21 is formed in a long hole shape so as not to interfere with the pull rod 8 when the rotating lever 16 rotates (see FIG. 2).

The operation of the overwinding prevention device having the above structure will be described with reference to FIGS. 3 and 7 to 10. In a normal state, as shown in FIG. 3, the push lever 12 is constantly urged upward by the self-weight of the overwinding prevention lever 11, and the contact of the micro switch 2 is closed. Has been.

The turning lever 16 is an overwinding prevention lever.
A rod pin 19 provided on the support plate portion 11a of 11 is biased upward, and a distance d is maintained between the diagonal flat plate portion 16b of the rotating lever 16 and the locking nut 22.

Next, the hook device comes into contact with the tip end side of the overwinding prevention lever 11 to rotate the overwinding prevention lever 11 counterclockwise by the first step as shown by the arrow in FIG. If you do, the push lever 12 that follows the overwinding prevention lever 11,
By its own weight and a spring built into the micro switch 2, it rotates downward until it abuts on the upper surface of the second support shaft 15,
The micro switch 2 operates (projects) to demagnetize the exciting coil of the electromagnetic switch and stop the rotation of the hoisting motor.

In this case, the rotary lever 16 is also attached to the rod pin 19
Although it rotates a little downward by the rotation lever 16, there is still a gap d2 between the slanting flat plate portion 16b of the rotation lever 16 and the locking nut 22, and the pull rod 8 is not applied with a downward external force.

Next, in the unlikely event that the contacts of the electromagnetic switch of the hoisting motor are welded or mechanically broken, the contacts cannot be opened at all, as shown in FIG. The lever 11 rotates counterclockwise as indicated by the arrow, the rotation lever 16 is pushed down by the rod pin 19, and the inclined flat plate portion 16b of the rotation lever 16 is provided at the lower end portion of the pull rod 8. The state where it comes into contact with the stop nut 22 is reached.

When the overwinding prevention lever 11 is further rotated counterclockwise, as shown in FIG.
As a result, the turning lever 16 is forcibly pushed down, and the pull rod 8 of the main switch 3 is forcibly pulled down. As a result, the contacts of the main switch 3, which is provided separately from the series of electromagnetic switches, are opened, and the power supply circuit of the hoisting motor is reliably cut off. Up to this point, the rod pin 19 has slid in the linear elongated hole portion 18a provided in the rotating lever 16.

Further, when the overwinding prevention lever 11 is forcibly rotated beyond the specified value due to an external force, a shake of load, or the like,
As shown in FIG. 10, the rod pin 19 moves to the arc-shaped oblong hole portion 18b provided in the rotation lever 16. Then, since the arc-shaped elongated hole portion 18b is formed with the radius of rotation R about the first support shaft 10, the rod pin 19 has the arc-shaped elongated hole portion 18b.
As it moves while sliding b, the rotating lever 16 does not operate and no external force is applied to the pull rod 8.

Moreover, since the rotary lever 16 forms one side of the slide link mechanism composed of the second support shaft 15, the first support shaft 10 and the rod pin 19, the rotary lever 16 does not return to its original position. The angle continues to be maintained, and the contact of the main switch 3 remains open. When the overwinding prevention lever 11 rotates clockwise and returns to the original state, the rotation lever 16 and the push lever 12 automatically return to their original states.

[0040]

According to the first aspect of the invention, when the overwinding prevention lever is rotated in the first step, the exciting coil of the electromagnetic switch is demagnetized to stop the rotation of the hoisting motor, and the second step is rotated. In the case of turning, the power supply circuit of the hoisting motor can be surely cut off, and the function as the overwinding preventing device can be sufficiently fulfilled.

Further, when the overwinding prevention lever is forcibly rotated more than the specified value due to an external force, a shake of load, etc., the rotation of the overwinding prevention lever is caused by the arc-shaped elongated hole portion provided in the rotation lever. It is absorbed and no external force is applied to the pull rod. Therefore, the guide plate of the main switch and the pull rod can be prevented from being damaged.

Since the flat plate portion of the rotating lever that abuts the pull rod is formed obliquely, the pull rod is converted into a linear motion by the rotational movement of the overwinding prevention lever.
No excessive force is applied and no bending force acts on the tension rod.

According to the second aspect of the present invention, since the externally exposed portion of the overwinding prevention device is housed between the two support plates, damage can be avoided even if it is accidentally brought into contact with the packing base or the like. You can

[Brief description of drawings]

FIG. 1 is a front view showing one embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

3 is a cross-sectional view taken along the line BB of FIG.

FIG. 4 is a sectional view taken along line CC of FIG. 3;

FIG. 5 is a sectional view taken along the line DD of FIG. 3;

FIG. 6 is a front view of the rotating lever shown in FIG.

FIG. 7 is an operation sequence explanatory diagram of the overwinding prevention device of the present invention,
It is a figure which shows the place which the overwinding prevention lever rotated.

FIG. 8 is an operation sequence explanatory diagram of the overwinding prevention device of the present invention,
FIG. 8 is a view showing a state where the overwinding prevention lever of FIG. 7 is further rotated.

FIG. 9 is an operation sequence explanatory diagram of the overwinding prevention device of the present invention,
FIG. 9 is a view showing a state where the overwinding prevention lever of FIG. 8 is further rotated.

FIG. 10 is an operation sequence explanatory diagram of the overwinding prevention device of the present invention, and is a view showing a state where the overwinding prevention lever of FIG. 9 is further rotated.

FIG. 11 is a front view showing a general configuration of a conventional electric hoist.

FIG. 12 is a partial sectional front view showing a main part of a conventional overwinding prevention device for an electric hoist.

[Explanation of symbols]

 1 Hoist wiring box 2 Micro switch 3 Main switch 8 Tensile rod 9 Support plate 10 First support shaft 11 Overwinding prevention lever 12 Push lever 12a Support arm part 15 Second support shaft 16 Rotating lever 16a Support arm part 16b Oblique flat plate part 18 oblong hole 18a straight oblong hole 18b arcuate oblong hole 19 rod pin 21 hole d spacing

Claims (2)

[Claims] 1. A hoist wiring box containing a micro switch for opening and closing an electromagnetic switch of a hoisting motor and a main switch for connecting and disconnecting a power supply circuit of the hoisting motor is provided with two support plates below the hoist wiring box. An overwinding prevention lever and a support arm portion of a push lever that drives the microswitch by following this are rotatably pivotally attached to a first support shaft between the support plates, and further, between the support plates. The second support shaft is rotatably pivoted with a support arm portion of a rotary lever having a substantially U-shaped plane in which a linear elongated hole portion and an arcuate elongated hole portion continuous with the linear elongated hole portion are provided on a side portion. A rod pin provided at the base end of the overwinding prevention lever is slidably engaged with the elongated hole of the rotation lever, and a pull rod for opening and closing the contact of the main switch is attached to the rotation lever diagonally. Insert into the hole drilled in the flat plate, An electric hoist overwound preventing device, characterized in that a predetermined gap is maintained between the lower end of the pull rod and the rotary lever. 2. A push lever for activating a micro switch, a rotating lever for activating a main switch, and a lower end portion of a pull rod are housed between two support plates so as not to be exposed. Item 1. An electric hoist overwinding prevention device according to Item 1.