JPS5935834B2 - Overload prevention device - Google Patents

Description

[Detailed Description of the Invention] [Field of Invention Technology] The present invention relates to a loading machine, such as a hoist or an electric hoist, which performs cargo handling work by connecting a load to a wire rope wound around a winding drum. This invention relates to improvements to overload prevention devices.

[Prior art]

Generally, the starting torque of the electric motor that drives the hoisting machine is several times higher than the rated torque, so if you make a mistake in estimating the load and hoisting a load that exceeds the rated load, it may cause wire rope breakage or damage to the aircraft. Premature damage could occur.

In order to prevent such a situation from occurring, overload prevention devices have conventionally been installed on hoisting machines, electric hoists, and the like.

First, an electric hoist equipped with an overload prevention device will be explained with reference to FIG.

In the figure, 1 is a support frame, 2 is a suppressor box connected to this support frame 1, 3 is a push button switch that controls the controller of this controller box 2, and 4 is a deceleration device for a hoisting motor (not shown). (
A winding drum 5 is connected to the winding drum 4 through a winding drum 4 (not shown), and one end thereof is fixed to the winding drum 4 and is wound around the wire, and the other end is connected to an equalizer 6 connected to the support frame 1. Rope 1 is a hook block that is suspended by this wire rope 5 and moves up and down with the movement of the wire rope 5,
A load is suspended on the hook 8.

9 is a limit switch for preventing swirling coupled to the support frame 1; 10 is an overload prevention device installed at an appropriate location between the hook block 7 of the wire rope 5 and the equalizer 6; 11 is the above-mentioned This is an alarm device consisting of a buzzer, a lamp, etc. connected to the controller 2, and is driven by the overload prevention device 10.

Next, a conventional overload prevention device used in electric hoists and the like will be explained with reference to FIG.

In the figure, 12 is the casing 1 of the overload prevention device 10.
3 is one groove wheel coupled to this casing 12; 14;
15 is the other groove wheel connected to the casing 12, 15 is the shaft connected to the casing 12, and 16 is the shaft 15.
The lever 1T is rotatably supported on the lever 16 of C.
A groove wheel is connected to one end with a pin 18, 19 is a projection member connected to the other end of the lever 16, 20 is an elastic support connected to the casing 12, and the projection member 1
A through-hole 20a into which the holder 9 is loosely fitted is provided.

Reference numeral 21 denotes an elasticity adjustment member screwed onto a male screw 19a carved in the projection member 19, and 22 a predetermined spring that loosely fits into the projection member 19 and between the elastic body receiver 20 and the adjustment member 21. 23 is a microswitch coupled to the casing 12; 24 is a movement regulating member coupled to the casing 12; and the lever 16 is connected to the elastic body 22. Due to the elasticity of the lever 16, the movement of the lever 16 is restricted so that the contacts of the microswitch 23 are not pressed with more than necessary force.

Reference numeral 5 denotes a wire rope whose one end is connected to the equalizer 6 and whose other end is wound around the winding drum 4 and suspends the hook block 7 on which the load is suspended. As shown in the figure, until the rated load is reached, it is held between the groove wheels 13, 14 and 17, and due to the elasticity of the elastic body 22, a predetermined pressing force is applied between the groove wheels 13, 14, and 17. It is pressed and bent into a dogleg shape.

The elastic body 22 is set so as not to be displaced within the range of the tension applied to the wire rope 5 until the load suspended on the hook block 7 reaches the rated load.

Further, the microswitch 23 is configured to close when the lever 16 is pressed and open when the lever 16 is not pressed.

Further, the microswitch 23 is connected to the operating circuit of the hoisting motor, and cuts off the operating circuit when opened.
Alternatively, a warning device such as a buzzer or a lamp is activated.

Next, the operation of the device configured as described above will be explained.

When a load below the rated load is suspended on the hook 8 of the hook block 7 and the hoisting motor is rotated to hoist or lower the load, the tension applied to the wire rope 5 is below the rated load, and therefore the groove wheel Since the component of the tension that presses the lever 17 is also less than the rated value, the lever 16 comes into contact with the movement regulating member 24 due to the elasticity of the elastic body 22, and the microswitch 2
3 is pressed, the hoisting motor continues to rotate, and the alarm device does not operate.

If the load exceeds the rating, wire rope 5
The tension applied to the groove wheel 17 is also greater than the rated tension, and the lever 16 rotates about the shaft 15 as a fulcrum against the elasticity of the elastic body 22 due to a component of the tension applied to the groove wheel 17.

Therefore, the pressing force of the lever 16 against the microswitch 23 is removed, and the microswitch 23 is opened to stop the hoisting motor and activate the alarm device, thereby preventing overload on the wire rope 5 and the machine body. ing.

As described above, the conventional overload prevention device uses wire rope 5.
Because the wire rope is held and pressed by three groove wheels 13, 14, and 17, and because the lever mechanism receives a component of the tension applied to the wire rope 5, the device has the disadvantage of being large. .

For this reason, when this device was used in an electric hoist, there was a drawback that the head could not be made smaller.

Furthermore, since the wire rope 5 is supported at three points, the wire rope 5 bends in a dogleg shape, causing the wire rope 5 to become deformed, resulting in a drawback that the tension applied to the wire rope 5 cannot be detected with high precision.

In addition, the number of parts is large, and the groove wheel 13 is attached to the casing 12.
°14, shaft 15, movement regulating member 24, elastic body receiver 20,
It is necessary to connect the microswitch 23, which has the drawback of increasing the number of man-hours and cost in addition to the large number of parts mentioned above.

[Summary of the invention]

This invention was made in an attempt to eliminate such drawbacks of the conventional device, and includes a rope supporting tension and a bent through hole, and the rope is inserted into the through hole and supported by the rope. an elastic body having one end connected to the support member and formed into an arc shape so as to bend the rope, the radius of curvature changing according to changes in the tension applied to the rope, and the other end of the elastic body a guide member coupled to the guide member to guide the rope along the elastic body; a first lever having one end rotatably connected to the other end of the elastic body and the other end extending toward substantially one end of the elastic body; , a switch coupled to the other end of the first lever and having an actuating body for opening/closing operation; a switch coupled to one end of the elastic body and engaged with the actuating body based on a change in the radius of curvature of the elastic body; By providing a second lever that opens and closes the switch by changing the actuating body according to a change in the relative position between the switch and one end of the elastic body, it is possible to prevent unloading in a small, inexpensive and highly accurate manner. The purpose is to provide equipment.

[Embodiments of the invention]

Next, an embodiment of the present invention will be described with reference to FIGS. 3 and 4.

In the figure, reference numeral 25 denotes an arc-shaped elastic body made of an arc-shaped plate spring, and a plurality of through holes (not shown) are provided at both ends of the elastic body in the longitudinal direction.

Reference numeral 26 denotes a supporting member having a bent through hole 26a passing through the wire rope 5, which will be described later, and a threaded portion 26b passing through the through hole 12a of the casing 12. As shown in FIG.
0 and a nut 41, it is supported by the casing 12.

Note that a gap is provided between the casing 12 and the washer 40, and the support member 26 is rotatably supported by the casing 12 by this gap.

5 has one end connected to the equalizer 6, and the supporting member 2
6, a wire rope 27 that abuts the protruding end surface of the arcuate elastic body 25, the other end of which is wound around the winding drum 4 and suspends the hook block 7 on which the load is suspended;
28 is a fastening member consisting of a bolt and a nut that connects the support member 26 and the arc-shaped elastic body 25, and the wire rope 5 is connected to one end of the arc-shaped elastic body 25 through the support member 26. It is designed to be tightly attached to.

Reference numeral 29 is a fastening member consisting of a metal 30 and a nut 31 that can be slidably connected to the wire rope 5, and is connected to the other end of the arc-shaped elastic body 25 to constitute a guide member; 32 is a guide groove whose one end is connected to the nut; 28 is one connecting member that is connected to one end of the arc-shaped elastic body 25 to constitute a second lever, and has a rotatable shaft portion 32a at the other end 23C, and a through hole in the center. 32b.

Reference numeral 33 designates the other connecting member whose one end is connected to the other end of the arc-shaped elastic body 25 by the nut 31 to constitute a first lever, and has a rotatable shaft portion 33a at the other end. There is.

34 has one end portion 34b loosely fitted into the rotating portion 33a, and the rotating portion 32-3. - a switch coupling member adapted to be able to slide around the shaft 38 loosely fitted into the switch coupling member 34; 23 a control means comprising a microswitch coupled to the switch coupling member 34; 35 a through hole 3 of the one support member 32;
An actuating body 36 that penetrates through 2b and comes into contact with and presses the microswitch 23 is an adjusting member made of a nut screwed to one end of the actuating body 35. The protrusion length is adjustable.

Note that the radius of curvature of the arc-shaped elastic body 25 changes depending on the tension applied to the wire rope 5, but it is designed so that the pressing force of the actuating body 35 against the microswitch 23 does not disappear when the load is less than the rated load. It is adjusted by the adjustment member 36.

Further, the microswitch 23 is configured to close when pressed by the operating body 35, and to open when not pressed.

Further, the microswitch 23 is connected to the operating circuit of the hoisting motor, and cuts off the operating circuit when opened.
Alternatively, a warning device such as a buzzer or lamp is activated.

Next, the operation of the device configured as described above will be explained.

When a load less than the rated load is suspended on the hook 8 of the hook block 1 and the hoisting motor is driven to hoist or lower the load, the tension applied to the wire rope 5 is less than the rated value, and therefore the arc shape Since the change in the radius of curvature of the elastic body 25 is small, the operating body 35 contacts and presses the microswitch 23, the hoisting motor continues to rotate, and the alarm device does not operate.

When the load is higher than the rated load, the tension applied to the wire rope 5 is also higher than the rated tension, and the arc-shaped elastic body 2
The radius of curvature of 5 changes so that it becomes a dog.

When the radius of curvature of the arc-shaped elastic body 25 becomes dog, the connecting member 3
2 and 33 in the opening direction, the pressing force of the operating body 35 against the microswitch 23 is removed, and the microswitch 23 is opened to cut off the operating circuit of the hoisting motor or operate the alarm device. .

The adjustment member 36° is used to adjust the contact state between the actuating body 35 and the microswitch 23.

Although this embodiment has been described as an overload prevention device for an air hoist, the same effect can be achieved even if the device is used as an overload prevention device for a fixed main rope of a rope crane, for example.

Further, by adjusting the adjustment member 36, the contact state between the actuating body 35 and the microswitch 23 can be adjusted, and the electric motor serving as the drive source can be stopped as necessary not only in the case of overload but also in the case of light load. You can also do it.

Furthermore, in the above description, the support member 26 is supported by the casing 12, but the casing 12 covers the device and does not necessarily need to be provided in applications that do not require dustproofing or rainproofing. [Effects of the Invention] As described above, the present invention has a rope that supports tension and a bent through hole, into which the rope is inserted,
a support member supported by the rope; an elastic body having one end connected to the support member and formed into an arc shape so as to bend the rope, and whose radius of curvature changes according to the degree of tension applied to the rope; The inner part 7 is connected to the other end of the elastic body to make the rope run along the elastic body, one end is rotatably connected to the other end of the elastic body, and the other end extends to approximately one end of the elastic body. a switch connected to the other end of the first lever and having an actuating body for opening/closing; a switch connected to one end of the elastic body and engaged with the actuating body; A second lever is provided that displaces the actuating body in response to a change in the relative position between the switch and one end of the elastic body based on a change in the radius of curvature to open and close the switch, so that the second lever is coupled to the casing. The parts serve as supporting members, which not only reduces the cost of joining and processing, but also reduces the number of parts, further reduces size and cost, and provides a highly accurate device.

[Brief explanation of the drawing]

FIG. 1 is a side view of an electric hoist equipped with an overload prevention device, FIG. 2 is a front view of a conventional overload prevention device, FIG. 3 is a front view showing an embodiment of the present invention, and FIG. 4 is a front view of an electric hoist equipped with an overload prevention device. I in Figure 3
It is a sectional view taken along the V-IV line. In the figure, 1 is a support frame, 2 is a control box, 3 is a push button switch,
4 is a winding drum, 5 is a wire rope, 6 is an equalizer, 7 is a hook block, 8 is a hook, 9 is a swirl prevention limit inch, 10 is an overload prevention device, 111 is a warning device, 12
23 is a casing, 23 is a microswitch, 25 is an arc-shaped elastic body, 26 is a support member, 27, 28, 30, 31 is a fastening member, 29 is a guide groove wheel, 32, 33 is a connecting member, 3
2a and 33a are shafts, 34 is a switch coupling member, 35 is an operating body, 36 is an adjustment member, and 38 is a shaft. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A rope supporting tension, having a bent through hole, into which the rope is inserted, a support member supported by the rope, one end of which is coupled to the support member, and the rope can be bent. an elastic body that is formed in an arc shape and whose radius of curvature changes according to changes in the tension applied to the rope;
A guide member is connected to the other end of the elastic body and guides the rope along the elastic body, one end is rotatably connected to the other end of the elastic body, and the other end extends to substantially one end of the elastic body. a switch that is connected to the other end of the first lever and has an actuating body for opening/closing; a switch that is connected to one end of the elastic body and has a curvature of the elastic body; An overload prevention device comprising a second lever that changes the actuating body to open and close the switch in accordance with a change in the relative position between the switch and one end of the elastic body based on a change in radius.