JP2024080778A - Electric hoist control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric hoist control device capable of stopping a winding operation without putting any load on a motor etc. even if a drum inertially rotates in the hoisting direction after cutting off power to the motor.

SOLUTION: An electric hoist control device comprises a drum to wind up a rope using a motor as a power source, a normally open switch to output a control signal to a motor control circuit, and a switch lever rotating by a certain angle in forward and reverse directions to enable the switch to be turned on and off. The switch lever is provided with a cutoff part which has two parallel bars directly under the drum with an initial distance that a rope can pass through and which can be opened and closed. The rope is provided with a bump-like swollen part larger in outer dimensions than the initial distance. The switch lever rotates forward to the on-side of the switch by the swollen part pushing up the cutoff part when hoisting the rope and the cutoff part is allowed to pass to the drum side by expanding the two bars with the swollen part if the rope continues to wind up in that state.

SELECTED DRAWING: Figure 7

COPYRIGHT: (C)2024,JPO&INPIT

Description

This invention relates to a control device for an electric hoist, and to a configuration that stops the hoisting operation without applying a load to the motor or main body.

Conventionally, as a device for preventing excessive lifting of a load (hereinafter also referred to as "over-winding") in an electric hoist, a known over-winding prevention device is provided in which a spring guide is provided via a shock absorbing spring on a hoisting fitting attached to the end of the wire rope wound around a drum, and an over-winding limit rod and a limit switch for detecting over-winding are provided at the exit of the wire rope in the hoist body (Patent Document 1).

When the wire rope is wound up too far, the spring guide comes into contact with the lower end of the limit rod, pushing the limit rod up. This push-up activates the overwinding detection limit switch, cutting off the winding circuit and automatically stopping the electric hoist.

Japanese Utility Model Application Publication No. 04-135584

In the device of Patent Document 1, when the electric hoist is automatically stopped, the shock absorber spring absorbs the shock when the spring guide abuts against the limit rod. However, in reality, the drum continues to rotate in the winding direction even after the winding circuit is cut off. The higher the winding speed and torque, the longer it will rotate and the greater the torque. During this inertial rotation, the buffer spring compresses, but the repulsive force acts on the drum as a rotational force in the opposite direction to the winding direction, placing a load on the motor and the power transmission mechanism (gear) between the motor and drum. Furthermore, if the buffer spring reaches its compression limit before the drum comes to a complete stop, the buffering effect of the buffer spring cannot be obtained, and equipment failure due to overwinding is unavoidable.

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a control device for an electric hoist that can stop the hoisting operation without placing a load on the motor, etc., even if the drum rotates by inertia in the hoisting direction after the power supply to the motor is cut off.

In order to achieve the above-mentioned object, the present invention uses a drum that uses a motor as a power source to wind up the rope, a normally open switch that outputs a control signal to the motor's control circuit, and a switch lever that rotates forward and backward a certain angle to turn the switch on and off. The switch lever is provided with a cutoff section that can be opened and closed with an initial gap where the rope passes through two parallel bars directly below the drum, and the rope is provided with a knob-shaped bulge that has an outer shape larger than the initial gap. When the rope is wound up, the bulge pushes up the cutoff section that is at the initial gap, causing the switch lever to rotate forward to the on side of the switch, and if the rope continues to be wound up in this state, the bulge spreads the two bars and passes the cutoff section to the drum side, and at the same time rotates backward under its own weight to the off side of the switch.

According to this means, the switch lever is initially in a state where the switch is turned off, and when the bulge pushes up the cutoff section, it rotates forward to turn the switch on, and after the bulge passes, it rotates backwards by its own weight to return to the initial state. A control signal is output from the switch that is turned on to the control circuit, and the control circuit controls the motor accordingly. Typically, the control circuit that receives the control signal from the switch cuts off the power to the motor and stops the motor to prevent overwinding. Even if the motor (drum) continues to rotate by inertia and the winding operation after the power is cut off, in this invention, the cutoff section, which has two bars spread apart by the bulge, allows the bulge to pass to the drum side, allowing the winding operation (inertia rotation) until the motor (drum) completely stops. Therefore, the winding operation can be completed without putting a load on the motor, etc. It is to be noted that there is no restriction on the method of paying out the rope from the drum, but in that case, it is of course possible to pass the bulge by manually opening the cutoff section, etc.

As a means for reliably executing such a series of operations, the switch lever is made up of a pair of left and right lever bodies, one end of which is supported parallel to the rotation axis of the drum on the left and right lower sides of the drum, and the cutoff section is made up of two bars, a fixed bar and a movable bar, which are bridged between the pair of lever bodies so as to be able to open and close. It is preferable that the lever body has a long hole in the direction away from the fixed bar, the movable bar is slidably attached to the long hole, and the movable bar is biased toward the fixed bar by a spring to maintain the initial gap. According to this means, since the cutoff section maintains the initial gap by the spring, the two cutoff sections must be pried open against the elastic force of the spring in order for the bulging section to pass through the cutoff section. In other words, the spring acts as a passage resistance for the bulging section, and it is possible to prevent the bulging section from expanding the two bars and passing through without pushing up the cutoff section (without rotating the switch lever forward to the on side of the switch).

Furthermore, it is preferable that the long hole be inclined downward in the separation direction when the switch lever rotates forward to turn on the switch. By inclining the long hole in this way, resistance is generated to the opening of the movable bar, making it possible to more reliably prevent the bulge from passing through. In other words, the movable bar opens downward along the long hole in response to an upward force that tries to cause the bulge to pass through the blocking section, and this difference in orientation can reinforce the resistance of the spring to the passage of the bulge.

When an actuator that turns the switch on and off is integrally provided on the rotating shaft of the switch lever, a mechanism for turning the switch on and off can be easily obtained.

If an anti-entanglement section consisting of two parallel bars is provided directly below the cutoff section, the anti-entanglement section will correct the rope's sway and posture, allowing the rope to be guided vertically to the cutoff section when reeled in. Furthermore, the anti-entanglement section will regulate the hanging hardware, such as a hook, attached to the end of the rope, ensuring that the hanging hardware is prevented from getting entangled. Of course, the spacing between the parallel bars in the anti-entanglement section is greater than the outer shape of the bulge.

In addition, in the present invention, if there is only one bulge, the motor is typically stopped, but basically, the type of control the control circuit performs can be set arbitrarily. In other words, if the rope has two or more bulges, the motor control circuit can control the motor in a combination of two or more of acceleration, deceleration, and stopping according to the control signal obtained for each bulge when the rope is wound up.

According to the present invention, even if the drum rotates by inertia after the power supply to the motor is cut off to prevent overwinding, the winding operation can be stopped without putting a load on the motor or the main body. Moreover, by providing multiple bulges, it is possible to not only stop the motor, but also to perform various controls from acceleration to deceleration.

FIG. 1 is a perspective view of an electric hoist according to an embodiment of the present invention, viewed from the bottom left; FIG. Left side view of the same Left side view of the main part enlarged Operational diagram (bulge contact) Operation diagram (pushing up the breaker) Operation diagram (passing through the bulge) Operation diagram (after passing the bulge) FIG. 13 is a left side view showing the main part of an electric hoist according to another embodiment of the present invention.

A preferred embodiment of the present invention will now be described with reference to the attached drawings. Figures 1 to 4 show an electric hoist according to one embodiment of the present invention, in which 1 is a drum, 2 is a switch, 3 is a switch lever, and 4 is a cutoff section. Note that in Figures 2 and 3, the frame and other parts have been appropriately removed and are shown in perspective to show the main parts, and in Figure 4, the main parts are shown in a further enlarged scale.

As shown in Figures 1 and 2, the drum 1 is supported by the left and right main frames 5, 5 so that it can rotate forward and backward. In this embodiment, the drum 1 is hollow inside, and the motor M is housed in this cavity, adopting a "spool-in motor" as used in electric fishing reels, and the left main frame 5 is provided with a gear box GB such as a planetary gear that transmits the power of the motor M to the drum 1. As shown in Figure 3, a rope R is wound around the drum 1, and a knob-shaped bulge T is provided at an arbitrary position on the rope R. As described later, the bulge T pushes up the blocking part 4 and then pries it open to pass through it, so the material is preferably synthetic fiber, which is relatively smooth, but it may be synthetic resin or metal as long as it is a material that does not hinder passage through the blocking part 4. For the same reason, the shape of the bulge T is not limited to the oblong spheroid shown in the figure, and any appropriate shape such as a perfect circular sphere, an oblate spheroid, or a diamond-shaped solid may be selected.

The switch 2 is connected to the control circuit (not shown) of the motor M, and in this embodiment, a normally open microswitch consisting of a snap action mechanism with a pin push button 7 is used. As shown in Figure 1, the switch 2 is attached to the outside of the left mounting plate 6 of the mounting plates 6, 6 that are provided extending below the main frames 5, 5, and the pin push button 7 protrudes horizontally from the side of the switch.

As shown in Figures 1 and 2, the switch lever 3 comprises a pair of long, thin lever bodies 8 and 9 on the left and right, which are integrated with a connecting bar 10. The end of the connecting bar 10 is rotatably supported on the inside of the mounting plates 6 and 6 by shafts 11 and 12 that are parallel to the rotation axis of the drum 1. The shaft 11 of the left lever body 8 extends to the outside of the mounting plate 6, and an actuator 13 that turns the switch 2 on and off is integrally provided on this extension, as can be seen clearly in Figures 3 and 4.

Furthermore, the switch lever 3 has a cutoff section 4 installed directly below the drum 1 on the opposite side of the connecting bar 10, as shown in Figure 2. As shown in Figures 3 and 4, the cutoff section 4 is made up of two round bars 15 and 16 that are parallel to each other at the front and rear, with an initial gap L1 between them through which the rope R passes. However, this initial gap L1 is smaller than the maximum diameter D of the bulge T provided on the rope R. Of the two bars 15 and 16, the rear bar 15 is a fixed bar and the front bar 16 is a movable bar, allowing the initial gap L1 to be expanded to an expanded gap L2 through which the bulge T can pass. Specifically, both ends of the fixed bar 15 are fixed to the lever bodies 8 and 9, while both ends of the movable bar 16 are inserted into long holes 18 formed in the lever bodies 8 and 9. Therefore, the movable bar 16 slides away from the fixed bar 15 through the long hole 18, allowing the blocking section 4 to open and close from the initial gap L1 to an expanded gap L2 through which the bulge T can pass.

Furthermore, as shown in FIG. 4, the lever bodies 8 and 9 house a spring 19 on the extension of the long hole 18, which biases the movable bar 16 toward the fixed bar 15, so that the initial distance L1 is normally maintained.

In this embodiment, a winding prevention part 22 consisting of two parallel bars 20 and 21 is provided directly below the cutoff part 4 in the same direction as the cutoff part 4. The distance L3 between the parallel bars 20 and 21 of the winding prevention part 22 is large enough for the bulge part T to pass through. This winding prevention part 22 prevents the rope R from swinging back and forth during the winding operation, and allows the rope R to be introduced into the cutoff part 4 in a vertical position. This winding prevention part 22 also prevents the hanging hardware 14 from being entangled. Furthermore, in this embodiment, the winding prevention part 22 (rear parallel bar 20) supports the switch bar 3 from below and restricts the switch lever 3 from rotating further downward (reverse rotation), thereby maintaining the switch 2 in the off state as shown in Figures 3 and 4.

Next, the operation of the electric hoist in this embodiment will be explained with reference to Figures 5 to 8. For ease of explanation, the drum 1 and spring 19 are not shown. When the rope R is wound up, the bulge T provided in the middle of the rope rises and abuts the cutoff section 4 from below (Figure 5). Since the initial distance L1 of the cutoff section 4 is smaller than the bulge T, the cutoff section 4 is then pushed up by the bulge T, causing the switch lever 3 to rotate clockwise in the drawing, and the actuator 13 integrated with the shaft 11 also rotates in the same direction, turning on the switch 2 (Figure 6). When the switch 2 is turned on, a control signal is output to the control circuit, which, for example, cuts off the power to the motor M to stop the winding operation.

However, immediately after the power supply to the motor M is cut off, the motor M rotates by inertia, so the winding operation continues. The bulge T continues to rise due to this winding operation by inertia, but the switch lever 3 is restricted from further forward rotation by the frame mounting bar 23 with the switch 2 turned on. That is, in this embodiment, the frame mounting bar 23 and the winding prevention part 22 arranged above and below the switch lever 3 limit the forward and reverse rotation of the switch lever 3 to a certain angle α, as shown in FIG. 4. After the forward rotation of the switch lever 3 is restricted by the frame mounting bar 23 in this way, the bulge T pries open the movable bar 16 (FIG. 7). The bulge T then passes through the cutoff part 4 as it is, but as the force pushing up the cutoff part 4 is released at the same time as the bulge T passes through the cutoff part 4, the switch lever 3 rotates in the opposite direction by its own weight, and the switch 2 returns to the off state (FIG. 8). After that, the inertia rotation naturally stops and the winding operation is completed.

In this way, in the present invention, it is necessary to use the bulge T as a trigger, and rotate the switch lever 3 forward and backward as the bulge T pushes up and passes over the interrupter 4 to turn the switch 2 on and off. Therefore, if the bulge T does not push up the interrupter 4 and passes over it as it is, the switch lever 3 does not rotate forward and the switch 2 is not turned on.

This kind of straight passage of the bulge T can be avoided to some extent by biasing the movable bar 16 toward the fixed bar 15 with the spring 19 to maintain the initial gap L1, but in addition to this, in this embodiment, the long hole 16 is provided in a specific direction. That is, as shown in Figures 6 and 7, the long hole 16 is provided so as to incline downward relative to the lever body 8 in the direction away from the fixed bar 15 (widening direction) over the entire range in which the switch lever 3 (lever body 8) rotates forward by pushing up the blocking portion 4 of the bulge T. Since the direction of this long hole 16 is against the upward direction in which the bulge T rises, it acts as a resistance to the passage of the bulge T, preventing the bulge T from passing through, and the switch lever 3 can be reliably rotated forward to turn on the switch 2. However, even with this configuration, after the forward rotation of the switch lever 3 is restricted by the frame mounting bar 23, the bulge T continues to rise, as shown in Figure 8, and pushes open the cutoff section 4 against the elastic force of the spring 19 and the inclination of the long hole 16, passing through to the drum 1 side.

In the above embodiment, one bulge T is provided and control is given to stop the motor M (winding operation), but more precise control can be achieved by providing multiple bulges T1 to T4 as shown in FIG. 9. That is, the bulge T1 is used for acceleration, and when the switch 2 is turned on by the bulge T1, the motor M is accelerated by the control signal to speed up winding, and when winding is nearing completion, the motor M is gradually decelerated in the order of the bulge T2 and T3, and the current to the motor M is cut off by the bulge T4, allowing winding to be completed smoothly.

In this way, the present invention does not simply stop the motor to prevent overwinding, but achieves precise winding control by controlling the motor differently for each bulge section T1-T4. Note that the number of bulges and the control method are such that the motor needs to be stopped by at least one bulge section, but if two or more bulges are provided, any combination of controls such as motor acceleration and deceleration can be used.

REFERENCE SIGNS LIST 1 Drum 2 Switch 3 Switch lever 4 Breaking section 5 Main frame 6 Mounting plate 7 Pin push button 8, 9 Lever body 10 Connecting bar 11, 12 Shaft 13 Actuator 14 Suspension bracket 15 Fixed bar 16 Movable bar 18 Slot 19 Spring 20, 21 Parallel bar 22 Entrapment prevention section 23 Frame mounting bar M Motor GB Gearbox R Rope T Bulging section L1 Initial interval L2 Expanded interval D Maximum diameter of bulging section

Claims (6)

A control device for an electric hoist, comprising: a drum that uses a motor as a power source to wind up a rope; a normally open switch that outputs a control signal to a control circuit for the motor; and a switch lever whose tip is located directly below the drum and has a rotating shaft at its rear end that rotates forward and backward a certain angle to turn the switch on and off. The tip of the switch lever is provided with a cutoff section that can open and close two parallel bars with an initial gap through which the rope passes, and a knob-shaped bulge section with an outer shape larger than the initial gap is provided below the cutoff section on the rope. When the rope is wound up, the bulge section pushes up the cutoff section, causing the switch lever to rotate forward to the on side of the switch, and if the rope continues to be wound up in this state, the bulge section spreads the two bars and passes the cutoff section to the drum side, at the same time the switch lever rotates reversely under its own weight to the off side of the switch. The control device for an electric hoist according to claim 1, wherein the switch lever is made up of a pair of left and right lever bodies with one end supported parallel to the rotation axis of the drum on the left and right lower sides of the drum, and the blocking section is made up of two bars, a fixed bar and a movable bar, which are installed between the pair of lever bodies, and the lever body has a long hole in the direction away from the fixed bar, and the movable bar is slidably attached to the long hole to allow the blocking section to be expanded to a gap through which the bulge passes, and the movable bar is biased toward the fixed bar by a spring to maintain the initial gap. The control device for an electric hoist according to claim 2, in which the long hole is inclined downward in the separation direction relative to the lever body when the switch lever is rotated forward. A control device for an electric hoist as described in claim 1, 2 or 3, in which the switch lever has an actuator that turns the switch on and off integrally attached to its rotation axis. The control device according to claim 1 further comprises a hoisting hardware entrapment prevention section, which is provided parallel to the hoisting section and is formed by fixing two parallel bars at a distance greater than the outer shape of the bulge and smaller than the outer shape of the hoisting hardware provided at the end of the rope, directly below the hoisting section. The electric hoist control device according to claim 1, in which the rope is provided with two or more bulges, and the motor control circuit is capable of controlling the motor in a combination of two or more of acceleration, deceleration, and stopping according to a control signal obtained by turning on a switch for each of the bulges.

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