JPS60252594A - Preventive device for overwinding of winding machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field of the Invention] The present invention relates to a swirl prevention device suitable for preventing swirling up and down of hoisting machines such as electric chain hoists and electric hoists.

[Prior art]

A hoisting machine such as an electric chain hoist or an electric hoist is equipped with a swirl prevention device that prevents swirling up or down. An example of this will be explained using an electric chain hoist.

FIG. 1 is a diagram showing an electric chain hoist. The electric chain hoist main body 1 is suspended from a suitable ceiling member by an upper hook 2 fixed to two parts. By pressing the hoisting instruction pushbutton switch and the lowering instruction pushbutton switch of the operation box 3, the electric motor of the electric chain hoist main body 1 rotates forward or backward, hoisting or lowering the chain 4, and moving the lower hook 5 up or down. let

When the chain 4 is hoisted too much, the vortex detector 6 detects the vortex, and the detector 6 opens the normal rotation circuit of the motor to stop the hoisting. If the winding is lowered too much, the detector 6 detects the spiral lowering, and the reversing circuit of the motor is opened to stop the winding.

[Problems with conventional technology]

In the electric chain hoist mentioned above, when the hoist is raised or lowered, the detector 6 detects this and stops the motor. It does not stop; the motor continues to rotate due to inertia. Therefore, the supporting portion 5a of the lower hook 5 or the I-flange (not shown) attached to the rear end of the chain 4 may dig into the lever of the detector 6, causing damage to the detector 6. Accidents such as this will occur.

Therefore, on a part of the support part 5a of the lower hook 5 or on two parts of the stopper several times on the rear end of the chain 4,
A buffer spring 7 is provided to wrap around the chain, and the buffer stroke of the spring 7 prevents the above-mentioned accident from occurring. However, the dimensions of this spring 7 are as large as 75 mm to 00 mm, depending on the winding and lowering speeds, so that it is not possible to take a large winding and lowering stroke H of the electric chain block. In cases where the ceiling of the building is low and it is not possible to take a large hoisting stroke, there is a drawback that the cargo cannot be hoisted sufficiently, causing problems in cargo handling operations.

Incidentally, the above two problems also apply to hoisting machines such as electric hoists to a greater or lesser extent.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and provides an over-winding prevention device for a hoisting machine such as an electric chain hoist and an electric voice I-, which can take a large stroke for hoisting and lowering. The purpose is to

[Structure of the invention]

In order to achieve the above object, the present invention includes a first switch that rotates the motor in the forward direction and a second switch that rotates the motor in the reverse direction, and the first or second opening/closing is performed by operating a winding instruction switch or a lowering instruction switch. A winding machine that performs hoisting and lowering by operating a motor and rotating an electric motor in the forward or reverse direction; means to open the first switch and close the second switch to supply power in the reverse direction to the electric motor; and a means for supplying power in the forward rotation direction to the motor by opening the first switch and closing the first switch. Braking is applied to prevent winding and lowering due to inertia.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

Figure 2 shows the overwinding and up/down detection mechanism of an electric chain hoist, where (a) is a front view and (b) is a front view.
It is a partial sectional view on AA' of. 11 is a limit lever, and the limit lever 1] is a limit lever shaft 14.
It consists of two members fixed at both ends of the limit 1-
It is pivotally attached to the frame 13 of the electric chain hoist main body 12 so as to be rotatable clockwise and counterclockwise about a lever shaft 14.

16 and 17 are guide members that guide the chain 15, and the guide members 16 and 17 are respectively connected to the limit lever 11.
It is rotatably pivoted between. The guide member 16 is pushed up by a spring 19 mounted on a stopper 18 fixed to the rear end of the chain 15. The guide member I7 is pivotally attached to the limit lever 11 with a slight gap so that the chain 15 can be smoothly guided when the chain 15 is wound up and lowered at an angle.

22 is a limit switch, and the limit switch 2
2 is provided with a limit switch shaft 23, and the limit switch is operated by rotating the limit switch shaft 23 clockwise and counterclockwise. One end of the limit switch shaft 23 and the limit lever shaft 14 are connected by a connecting member 24.

In the above structure, the lower hook 20 is
For normal lowering, the stopper 18 pushes up the guide member 17 or the guide member 16 via the springs 21, 19. Therefore, the limit lever 11 rotates around the limit lever shaft 14 and tilts in the B-B' force direction when raising the spiral, and tilts in the cc' direction when lowering the spiral. This rotation of the limit lever shaft 14 rotates the limit switch shaft 23 via the connecting member 24, and the limit switch 22 is activated to detect spiral up or down spiral.

FIG. 3 is a circuit diagram showing the circuit configuration of the swirl prevention device.

M is a drive motor for the electric chain hoist, and is a three-phase AC motor. MC, 1 is a forward rotation electromagnetic switch that rotates the drive motor M in the forward direction and winds up the chain 15;
1a is its normally open contact, MC2 is a reversing electromagnetic switch that rotates the drive motor M in the reverse direction and lowers the chain 15, MC
2a is its normally open contact. LSla and LSlb are contacts of the limit switch 22, which are normally open contacts and normally closed contacts that operate during swirling. LS2b is also a contact of the limit switch 22, and is a normally closed contact that operates when the spiral is lowered. R is a relay, and R1 is its switching contact. P
B-U is a pushbutton switch that instructs the electric chain hoist to hoist, PR-D is a pushbutton switch that instructs the electric chain hoist to lower, and Tr is a transformer.

In the above circuit configuration, when the pushbutton switch PB-U is pressed, the switching contact R of the relay R and the normally closed contact L S 1.
b. Current flows through the forward rotation electromagnetic switch MCI, and the forward rotation electromagnetic switch MCI operates, closing its normally open contact MC1a. When the normally open contact MC1a closes, the drive motor M rotates forward and winds up the chain I5. When the swirling state occurs, the normally open contact L S of the limit switch 22 1. b is open, and normally open contact LS1a is closed. As a result, the forward rotation electromagnetic switch MCI becomes inoperable, the normally open contact MC1a is opened, and the power supplied to the drive motor M in the forward rotation direction is cut off. By closing the normally open contact S1a, the pushbutton switch PB-U and the normally open contact LSIa
A current flows through the relay R, and the relay R operates, switching its switching contact R1 from a to b.

By this switching, push button switch y P B-U, contact R
1 and b, the relay R is self-holding, and the pushbutton switch PB-U, switching contact R1, normally open contact LS1
a, Through the normally closed contact LS2b, electromagnetic opening/closing 8'i for reversal
ji MC2, current flows to reverse electromagnetic switch MC2
operates and closes its normally open contact MC2a. Normally open contact M
By closing C2a, power is supplied to the drive motor M in the reverse direction, and the drive motor M rotates slightly in reverse, but as soon as it reverses, the normally open contact LS1a of the limit switch 22 opens, and the electromagnetic switch MC2 for reverse rotation does not operate. Therefore, the drive motor M stops.

Figure 4 shows the circuit configuration of the swirl prevention device when a two-speed variable speed motor is used as the drive motor M. MC3 is an electromagnetic switch for low speed switching, MC3a is its normally open contact, and MC4 is an electromagnetic switch for high speed switching. MC4a is its normally open contact, M
C4b is a normally closed contact. The pushbutton switch PB-U for winding instructions is a switch that is pressed in two stages; in the first stage, contact 1.1 is closed, in the second stage, contacts 1-1 and 2.2 are closed, and then contacts 3 and 3 are closed. is push button switch P
Press B-U to release immediately. The push button switch PB-D for lowering the lowering instruction is also the push button switch PB-T.
This is a switch that has the same two-step pressing structure as J.

In the above circuit configuration, when the pushbutton switch PB-U is pressed, the normally closed contacts 3, 3 of the pushbutton switch PB-D
, normally open contacts 1, 1 of pushbutton switch PB-U, switching contact R1 of relay R, normally closed contact L S 1. A current flows through the forward rotation electromagnetic switch MCI through b, and the forward rotation electromagnetic switch MCI operates to close its normally open contact MC1a. When the normally open contact MCLa closes, the low speed switching electromagnetic switch MC3
, and closes its normally open contact MC3a, and at the same time, power is supplied to the drive motor M in the forward rotation direction, and the drive motor M rotates in the forward direction at a low speed to unwind the chain 15. When the spiral-whisker state is reached, the normally closed contact LS1b of the limit switch 22 is opened, the forward rotation electromagnetic switch MCI becomes inoperative, and the reverse rotation electromagnetic switch MC2 is activated, causing the drive motor M to rotate in the reverse direction. When electric power is supplied, the driving motor M rotates slightly in reverse, but immediately the normally open contacts LS and a open and the drive motor M stops, which is exactly the same as the circuit shown in FIG.

When the pushbutton switch PB-U is pushed to the second stage, its normally open contacts 1, 1 and 2, 2 close, and the pushbutton switch P
Current flows through the normally closed contacts 3 and 3 of B-D, the normally open contacts 2 and 2 of the pushbutton switch PB-U, and the switching contact R1 of the relay R to the electromagnetic switch MC4 for high-speed switching, and the electromagnetic switch for high-speed switching When the motor MC4 operates, its normally open contact MC4a closes and its normally closed contact MC4b opens, causing the drive motor M
Switch to high speed. Power is supplied to the drive motor M in the normal rotation direction through the normally open contact MCIa, and the drive motor M rotates at high speed to wind up the chain 15.

When the swirling state is reached, the normally closed contact L S 1 b of the limit switch 22 opens, cutting off the power supplied to the drive motor M, and the normally closed contact LS1 a closes, causing the relay R to close.
is activated, switching the switching contact R1 from a to b, and further opening the operating circuit of the high-speed switching electromagnetic switch MC4.

As a result, the reversing electromagnetic switch MC2 is activated, the high-speed switching electromagnetic switch MC4 is deactivated, and the normally open contact MC:2a and the normally closed contact MC4b are closed. By closing the normally open contact MC2a and the normally closed contact MC4b, the low speed switching electromagnetic switch MC3 operates, and the drive motor M
At the same time, power is supplied to the drive motor M in the reverse direction. As a result, the drive motor M rotates slightly in the reverse direction, but the normally closed contact L S1 of the limit switch 22.
b is immediately closed and the normally closed contact LS1a is opened, so the reversing electromagnetic switch MC2 becomes inoperable.

In addition, in the circuits shown in FIGS. 3 and 4, an example is shown in which the spiral up is detected and the electric power is supplied to the drive motor M in the reverse direction to apply braking in the reverse direction, but the spiral down is detected by the limit switch 22. Detected by the normally open contact, the forward rotation electromagnetic switch M
By activating the CI, supplying electric power in the forward rotation direction to the drive motor M, and applying braking in the forward rotation direction, the circuit configuration becomes slightly more complicated, but it is naturally possible to prevent the spiral down. A detailed explanation of this circuit will be omitted.

As explained above, according to the above embodiment, the spiral up and down spirals are detected by the spiral detection mechanism consisting of the limit switch 22 and the like, and the normally closed contact L of the limit switch 22
At S1b, the forward rotation electromagnetic switch MCI is deactivated to cut off the power in the forward rotation direction supplied to the drive motor M, and
The normally open contact LSIa operates the reverse electromagnetic switch MC2 to supply power in the reverse direction to the drive motor M.
Furthermore, when the limit switch 22 detects lowering,
The normally closed contact LS2b of the limit switch 22 disables the reverse rotation electromagnetic switch MC2 to cut off the power supplied to the drive motor M in the reverse direction, and the normally open contact operates the forward rotation electromagnetic switch MCI. Since power is supplied to the drive motor M in the forward rotation direction, the drive motor M is quickly stopped by braking in the reverse direction, so that the amount of hoisting and lowering of the chain 15 is reduced due to the inertia of the drive motor M during the hoisting and hoisting. can be made smaller, and the stroke for winding up and lowering can be increased accordingly. Moreover, especially when the ceiling of a building is low, the spring 21 can be omitted or made extremely short to increase the hoisting stroke, so that cargo handling operations can be carried out smoothly.

In addition, although the electric chain hoist was shown as an example in the said Example, the technique of this invention is not limited to an electric chain hoist, but can also be utilized for hoisting machines, such as an electric hoist.

〔Effect of the invention〕

As explained above, according to the present invention, when a vortex is detected by the vortex detection means, reverse braking is applied to the electric motor to quickly stop the electric motor. This provides an excellent effect in that the winding machine can be shortened by a considerable amount and the hoisting and lowering strokes of the hoisting machine can be made larger compared to conventional ones.

[Brief explanation of drawings]

Figure 1 is a diagram showing an electric chain hoist, Figure 2 is (a
), (b) are diagrams showing a suitable person detection mechanism according to an embodiment of the present invention, FIG. 3 is a circuit diagram of a pass prevention device according to an embodiment of the present invention,
FIG. 4 is a circuit diagram of an overwinding prevention device according to another embodiment. In the figure, 11...Limit lever, 12...Electric chain hoist body, 13...Frame body, 14...Limit lever shaft, 15...Chain, 16.17...Guiding member, 1
8. Stripper, 19.2] Spring, 20 Lower hook, 22 Limit switch, 23 Limit switch shaft, 24 Connecting member, PB-D Winding instruction push button switch, PB-D: Push button switch for lowering instructions, MCI: Electromagnetic switch for forward rotation, MC2
・・Solenoid switch for reversing, MC3・・Solenoid switch for low speed switching, MC4・・・Solenoid switch for high speed switching, R relay, L
S 1 a...Normally closed contact of limit switch, L
S1. b...Normally closed contact of limit switch, LS2
a... Normally closed contact of limit switch, L S 2 +)
・Normally closed contact of limit switch. Applicant Kito Co., Ltd. Agent Patent Attorney Takashi Kumagai 11th 12th Figure 2'0 (α) (b) 3rd

Claims (1)

[Claims] (1) A first switch that rotates the motor in the forward direction and a second switch that rotates the motor in the reverse direction are provided, and the first or second switch is operated by operating the hoisting instruction switch or the hoisting down instruction switch. In a hoisting machine that performs hoisting and lowering by rotating the electric motor forward or backward, the hoist includes a vortex detection means for detecting a vortex, and when the vortex detection means detects a vortex, the first switch is opened and the second Close the switch or open the second switch and open the first switch (
2) A vortex prevention device for a hoist according to claim 1, wherein an electric motor capable of changing speeds in multiple stages is used as the electric motor.