JP2006143368A - Lifting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lifting device, capable of preventing trouble due to loosening of a wire rope while using a simple DC motor without having a brake function. <P>SOLUTION: This device comprises the DC motor M of a reversible rotation type without including a brake function, a drum 6 connected to the DC motor M through a reduction mechanism 7, a wire rope 3 wound around the drum 6 to suspend lifted equipment, a detection switch SW4 to detect a loosened state of the wire rope 3, and a brake circuit to instantaneously short-circuit between terminals of the DC motor M when the detection switch SW4 is actuated as the lifting equipment is lowered. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lifting device that lifts and lowers a lifted device such as a lighting fixture.

  2. Description of the Related Art Conventionally, in a lifting device that lifts and lowers a device to be lifted such as a lighting fixture, as a technology for instantaneously stopping the rotation of a motor after detecting slack (sag) of a wire rope for suspension, there are the following conventional technologies.

  FIG. 4 is a sectional view showing a configuration of a conventional motor with a simple brake. In the figure, 10 is a stator, 11 is a rotor, 12 is an output shaft, 13 is a reduction gear, 14 is a brake plate, 15 is a brake shoe, and 16 is a brake spring. The motor rotor 11 is constantly pressed by the brake spring 16 via the brake shoe 15 and has a structure that brakes inertial rotation when the motor is stopped by the frictional force of the brake plate 14 and the brake shoe 15. It is a motor that rotates normally. When the motor is de-energized, the motor is quickly stopped by the brake function.

  FIG. 5 is a cross-sectional view showing the configuration of a conventional motor with an electromagnetic brake. The brake plate 14 of the motor with a simple brake is sucked by the brake coil 17 only when the motor is energized to release the brake and only when the motor is stopped. It has a structure for applying a brake. When this motor is also de-energized, it stops quickly due to the brake function.

  Thus, conventionally, in order to stop the rotation of the motor instantaneously after detecting the slack (sag) of the wire rope, a motor with a brake that stops quickly without inertia when it is energized has been adopted. It was. The motor with a brake includes a simple type shown in FIG. 4 and an electromagnetic type shown in FIG. 5, but the structure is complicated and expensive compared to a motor without a built-in brake function.

Patent Document 1 discloses an example in which when a lighting fixture is lowered and comes into contact with a floor surface, loosening of a wire rope is detected and the motor is stopped. Furthermore, Patent Document 2 discloses that a motor regenerative voltage is detected when a lift is lowered by a lifting motor, and a regenerative resistor is connected when a predetermined value is exceeded, so that the descent speed is optimized. The point of interlocking with the structure is not disclosed.
JP 2004-119137 A JP 2001-341987 A

  The present invention has been made in view of the above-mentioned points, and the object of the present invention is to be able to prevent troubles caused by loosening of the wire rope while using a simple DC motor having no brake function. To provide an apparatus.

  In the lifting device of the present invention, in order to solve the above problems, as shown in FIGS. 1 to 3, as shown in FIGS. 1 to 3, a reversible rotation type DC motor M without a built-in brake function and the DC motor M A drum 6 connected via a speed reduction mechanism 7, a wire rope 3 wound around the drum 6 to suspend a lifted device, a detection switch SW4 for detecting a loosened state of the wire rope 3, and a lifted And a braking circuit for instantaneously short-circuiting the terminals of the DC motor M via a resistor R3 when the detection switch SW4 is actuated when the device is in a lowered state.

  According to the present invention, when the lifted device is in a lowered state and the wire rope is in a slack state, the direct current motor is quickly stopped by the action of the braking circuit that instantaneously shorts the terminals of the direct current motor via a resistor. The rope can be prevented from loosening and the aligned winding on the drum can be maintained. In addition, even when it is descending, when the slack detection switch is not working, there is an advantage that no extra stress is applied to the motor because no short circuit is caused by resistance.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an internal configuration of an elevating device according to an embodiment of the present invention, and FIG. 2 is an explanatory view showing how a wire rope is stretched in the elevating device of FIG. 1 in a simplified manner.

  The lifting device includes a main body 1 including a power unit, a lifting unit 2 for attaching a lifted device, and a wire rope 3 that suspends the lifting unit 2 from the main body 1. The elevating unit 2 is attached to a lifted device such as a lighting fixture, and is suspended from the main body 1 by a wire rope 3. A pulley 4 for passing the wire rope 3 is attached to the elevating part 2. Via this pulley 4, the wire rope 3 can be wound or rewound while maintaining tension. A pulley 5 through which the wire rope 3 passes is also provided on the main body 1 side of the lifting device.

  One end of the wire rope 3 is fixed to the body 1 of the lifting device as a fixed end 3A, and the other end of the wire rope 3 is fixed to the shaft core portion of the drum 6 of the lifting device as a winding end 3B. ing. The wire rope 3 is wound around the drum 6. The drum 6 can be rotated forward, reverse, and stopped by a DC motor M. The rotational force of the DC motor M is transmitted to the rotating shaft of the drum 6 via the speed reduction mechanism 7. This DC motor M is a motor having a simple structure that does not have a brake function. However, when the DC motor M is stopped due to a large reduction ratio of the speed reduction mechanism 7, regardless of the load of the elevating unit 2, The drum 6 is designed to stop rotating, and the elevating unit 2 is designed to stop at a predetermined height.

  When the drum 6 of the lifting device rotates in one direction and the wire rope 3 is wound around the main body 1 of the lifting device, the lifting unit 2 moves up. When the drum 6 of the lifting device rotates in the opposite direction and the wire rope 3 is rewound from the main body 1 of the lifting device, the lifting unit 2 descends.

  An electric block 8 for driving the motor is built in the main body 1 of the lifting device. A circuit diagram of the electric block 8 for driving the motor is shown in FIG. V is a commercial AC power source, 8 is a motor drive electric block, S is a changeover switch, and M is a DC motor. The motor driving electric block 8 includes two diode bridge circuits DB1 and DB2. When the power is supplied to the first diode bridge circuit DB1 by switching the changeover switch S, the DC motor M is rotated forward. When the power is supplied to the second diode bridge circuit DB2, the DC motor M is reversely rotated.

  One end of the commercial AC power supply V is connected to a terminal A of the motor driving electric block 8. The other end of the commercial AC power supply V is connected to the contact Sa of the changeover switch S. The contact Sa of the changeover switch S can be selectively connected to any one of the ascending contact Sb, the descending contact Sc, and the stopping contact Sd. The ascending contact Sb is connected to the terminal B of the motor driving electrical block 8, and the descending contact Sc is connected to the terminal C of the motor driving electrical block 8.

  A thermal protector TP is connected between the terminals D and E of the electric block 8 for driving the motor. The thermal protector TP is mounted at a location where the temperature rise of the DC motor M can be detected. When the temperature of the DC motor M rises abnormally, the terminals D and E are opened. When the temperature of the DC motor M is in a normal range, the terminals D and E are short-circuited. The terminal A of the motor driving electric block 8 is connected to each end of the AC input terminals of the diode bridge circuits DB1 and DB2 via the terminal D, the thermal protector TP, the terminal E, and the fuse FS1. Therefore, when the thermal protector TP is opened or the fuse FS1 is disconnected, the power supply to the diode bridge circuits DB1 and DB2 is released.

  A plurality of micro switches SW1, SW2, SW3, SW4 are connected to the electric block 8 for driving the motor. SW1 is a micro switch for detecting overload, SW2 is a micro switch for detecting twist (twist), SW3 is a micro switch for detecting wire rope end, and SW4 is a micro switch for detecting looseness (slack). The overload detection micro switch SW1 is a switch that is opened when an overload is applied to the wire rope. The twist detection micro switch SW2 is a switch that is opened when the wire rope is twisted. The wire rope end detection micro switch SW3 is a switch that is opened when the wire rope 3 reaches the rewind limit.

  The slack detection micro switch SW4 is a switch that is opened when the wire rope 3 is slack. That is, tension is applied to the wire rope 3 due to the load of the equipment to be lifted, but if the equipment to be lifted does not apply tension to the wire rope 3 because the tension is not applied to the floor, the switch SW4 is assumed to be loose. Opened.

  A terminal B of the motor drive electric block 8 is connected to the other end of the AC input terminal of the diode bridge circuit DB1 through the fuse FS2, the overload detection micro switch SW1, and the torsion detection micro switch SW2. Therefore, when the DC motor M is energized in the upward direction, the fuse FS2 is disconnected, the overload detection microswitch SW1 is opened, or the twist detection microswitch SW2 is opened. Then, the energization to the DC motor M is stopped.

  The terminal C of the electric block 8 for driving the motor is connected to the other end of the AC input terminal of the diode bridge circuit DB2 via the micro switch SW3 for detecting the wire rope end. Therefore, when the DC motor M is energized in the downward direction and the wire switch end detection microswitch SW3 is opened, the energization to the DC motor M is stopped.

  In any of these cases, since the energization to the DC motor M is stopped in a state in which the wire rope 3 is under tension, the wire rope 3 does not loosen, and the wire rope 3 on the drum 6 is disturbed. Absent.

  Note that a parallel circuit of a non-linear resistance element ZNR1 and a capacitor C1 is connected to the series circuit of the AC input terminal of the diode bridge circuit DB1 and the micro switches SW1 and SW2 as a noise prevention element, and the AC input of the diode bridge circuit DB2 A series circuit of the terminal and the micro switch SW3 is connected with a parallel circuit of a nonlinear resistance element ZNR2 and a capacitor C2 as a noise prevention element.

  A capacitor C3 is connected in parallel between the DC output terminals of the diode bridge circuit DB1. A series circuit of a resistor R1, a normally closed contact RY2-3, and a relay coil RY1 is connected to both ends of the capacitor C3.

  A capacitor C4 is connected in parallel between the DC output terminals of the diode bridge circuit DB2. A series circuit of a resistor R2, a normally closed contact RY1-3, a slack detection microswitch SW4, and a relay coil RY2 is connected to both ends of the capacitor C4.

  The relay coil RY1 is a three-contact relay coil, and the first contact RY1-1 is connected as a normally open contact between the positive electrode of the capacitor C3 and the first input terminal of the line filter LF1, and the second contact RY1. -2 is connected as a normally open contact between the negative electrode of the capacitor C3 and the second input terminal of the line filter LF1. The third contacts RY1-3 are connected as a normally closed contact in series with the relay coil RY2 and the slack detection micro switch SW4.

  The relay coil RY2 is also a three-contact relay coil, and the first contact RY2-1 is connected as a normally open contact between the positive electrode of the capacitor C4 and the second input terminal of the line filter LF1, and the second contact RY2 -2 is connected as a normally open contact between the negative electrode of the capacitor C4 and the first input terminal of the line filter LF1. The third contact RY2-3 is connected as a normally closed contact in series with the relay coil RY1.

  Between a normally closed contact (contact indicated by a black circle) of the first contact RY1-1 corresponding to the relay coil RY1 and a normally closed contact (contact indicated by a black circle) of the first contact RY2-1 corresponding to the relay coil RY2. Is connected to a resistor R3 having a low resistance and a large watt for regenerative braking. Therefore, when both the relay coils RY1 and RY2 are not excited, the resistor R3 is connected in parallel between the first input terminal and the second input terminal of the line filter LF1.

  The line filter LF1 includes a filter transformer and a pair of filter inductors, and the first input terminal of the line filter LF1 is connected to the first output terminal via the first winding of the filter transformer and the first filter inductor. The second input terminal of the line filter LF1 is connected to the second output terminal via the second winding of the filter transformer and the second filter inductor. The first output terminal of the line filter LF1 is connected to the first DC output terminal F of the motor driving electric block 8 via an external inductor L1, and the second output terminal of the line filter LF1 is an external inductor. It is connected to the second DC output terminal H of the motor driving electric block 8 via L2.

  The first DC output terminal F is a positive or negative output terminal, and is a positive output terminal when energized to the diode bridge circuit DB1 side and a negative output terminal when energized to the diode bridge circuit DB2 side.

  The second DC output terminal H is a negative or positive output terminal, and is a negative output terminal when energized to the diode bridge circuit DB1 side, and a positive output terminal when energized to the diode bridge circuit DB2 side.

  A pair of terminals of a DC motor M is connected to these DC output terminals F and H. Between the ground terminal G and the DC output terminal F, a parallel circuit of a surge resistance absorbing nonlinear resistance element ZNR3 and a capacitor C5 is connected, and between the ground terminal G and the DC output terminal H, surge voltage absorption. A parallel circuit of a non-linear resistance element ZNR4 and a capacitor C6 is connected.

  Hereinafter, the operation of the circuit of FIG. 3 will be described. When the commercial AC power source V is connected between the terminals A and B of the motor drive electric block 8 by the changeover switch S, the voltage of the capacitor C3 rises due to the rectified output of the diode bridge circuit DB1, and the resistor R1 and the normally closed contact RY2 When the relay coil RY1 is excited via -3, the contacts RY1-1 and RY1-2 are switched from the normally closed side (contact indicated by a black circle) to the normally open side (contact indicated by a white circle), and the DC motor M The DC motor M is energized so that the motor rotates in the upward direction.

  When the changeover switch S is returned to the neutral position (position of the contact Sd shown), the power supply to the diode bridge circuit DB1 is cut off. At this time, the rectified output of the diode bridge circuit DB1 disappears, so that the energization to the DC motor M is cut off. In this case, since the energization to the DC motor M is stopped in a state in which the wire rope 3 is tensioned, the wire rope 3 is not slackened. Further, when the capacitor C3 is discharged and the excitation of the relay coil RY1 is released, the contacts RY1-1 and RY1-2 are switched from the normally open side (contact indicated by a white circle) to the normally closed side (contact indicated by a black circle), The resistor R3 is connected to the DC motor M. At that time, since the DC motor M has already stopped, no regenerative braking is applied to the DC motor M when the ascent is stopped. Since the torque due to the load of the lifted device is applied to the DC motor M at the time of ascent as compared to the time of the descent, the DC motor M is immediately stopped when energization is stopped even without regenerative braking.

  When the device to be lifted reaches the upper limit position and an overload is applied to the wire rope, the microload SW1 for overload detection is turned OFF, and when the twist is detected in the wire rope aligned and wound around the drum, the twist is detected. The microswitch SW2 for detection is turned OFF, and in these cases also, the power supply to the diode bridge circuit DB1 is cut off and the energization to the DC motor M is stopped.

  Next, when the commercial AC power supply V is connected between the terminals A and C of the motor drive electric block 8 by the changeover switch S, the voltage of the capacitor C4 rises due to the rectified output of the diode bridge circuit DB2, and the resistor R2, When the relay coil RY2 is excited via the closed contact RY1-3 and the slack detection micro switch SW4, the contacts RY2-1 and RY2-2 change from the normally closed side (contact indicated by a black circle) to the normally open side (white circle). The DC motor M is energized so that the DC motor M rotates in the downward direction.

  When the changeover switch S is returned to the neutral position (position of the contact Sd shown), the power supply to the diode bridge circuit DB2 is cut off. At this time, the rectified output of the diode bridge circuit DB2 disappears, so that the energization to the DC motor M is cut off. Further, when the wire rope end detection micro switch SW3 is turned OFF, the power supply to the diode bridge circuit DB2 is cut off and the energization to the DC motor M is stopped. In any case, since the energization is stopped in the lowered state, the DC motor M is slightly rotated after inertial rotation and then stopped. However, since the wire rope 3 is inertially rotated with the tension applied to the wire rope 3, There is no slack.

  When the power supply to the diode bridge circuit DB2 is cut off, the capacitor C4 is discharged and the relay coil RY2 is de-energized, so that the contacts RY2-1 and RY2-2 are normally opened from the normally open side (contacts indicated by white circles). Switching to the closed side (contact indicated by a black circle) and the resistor R3 is connected to the DC motor M. At this time, since the DC motor M is stopped, regenerative braking is applied to the DC motor M at the time of normal descent stop. There is no.

  Next, when the equipment to be lifted reaches the floor surface or when the wire rope 3 is slackened due to hitting a foreign object or the like, the microswitch SW4 for detecting slackness is turned OFF, and the energization to the relay coil RY2 is immediately stopped. The contacts RY2-1 and RY2-2 are opened to stop energization of the DC motor M.

  Even when the energization of the DC motor M is stopped, the DC motor M tries to continue rotating by inertial rotation. Therefore, the resistor R3 having a low resistance and a large watt is connected between the terminals of the DC motor M, so that the DC motor M acts as a generator and the inertia energy is consumed as Joule heat, thereby quickly stopping.

  Here, since the micro switch SW4 for detecting slackness is connected in series with the relay coil RY2, even if the electric charge of the capacitor C4 remains, the excitation of the relay coil RY2 can be immediately released. That is, when the DC motor M is energized so as to rotate in the downward direction, the changeover switch S is returned to the neutral position (the position of the contact Sd shown), or the wire rope end detection micro switch SW3. Is turned off, the excitation of the relay coil RY2 is released after the charge of the capacitor C4 is lost, but when the slack detection micro switch SW4 is turned off, the capacitor C4 does not wait for the charge to be lost. The contacts RY2-1 and RY2-2 are opened, and the terminals of the DC motor M are short-circuited by a resistor R3 having a low resistance and a large watt, thereby forcing regenerative braking. The DC motor M is quickly braked in a predetermined time by the resistance value of the resistor R3.

  Thus, when the wire rope 3 is rewound in a state in which no tension is applied to the wire rope 3 (when the wire slack detection switch SW4 is operated), the wire rope 3 expands due to inertial rotation of the motor M, and the drum In the present invention, there is a state in which the wire rope 3 bites in due to a state in which it is not aligned and wound, and in the present invention, this problem is detected on the circuit without using a motor with a brake function. It can be prevented with a small amount of parts. Therefore, an inexpensive small motor can be employed.

  Further, in the present invention, the regenerative braking is applied to the motor M only when the wire rope is slackened in the descending operation, and the wire rope 3 is prevented from loosening, but the brake is not applied during other operations, and the motor M is damaged. Can do. That is, when the wire rope 3 stops without slacking during the downward rotation (when stopped by the changeover switch S or by the function of the wire rope end detection microswitch SW3, etc.), the slackness detection microswitch SW4 is closed. Therefore, regenerative braking by the resistor R3 is not performed during inertial rotation of the motor M. The same applies when stopping while climbing. This is because if the frequency of regenerative braking is short-circuited between the terminals of the DC motor M by the resistor R3, the life of the motor M will be shortened. Therefore, in the present invention, the wire rope 3 may bulge. Further, the regenerative braking is performed only when the wire rope 3 is slack at the time of lowering, so that the motor life can be prevented from being shortened.

It is a perspective view which shows the internal structure of the raising / lowering apparatus which concerns on one embodiment of this invention. It is the schematic block diagram which simplified and showed the structure of FIG. It is a circuit diagram of the electric block for motor drive used for the raising / lowering apparatus of FIG. It is sectional drawing which shows the structure of the conventional motor with a simple brake. It is sectional drawing which shows the structure of the conventional motor with an electromagnetic brake.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Body of lifting device 2 Lifting part 3 Wire rope 6 Drum 7 Deceleration mechanism M DC motor SW4 Micro switch for slack detection

Claims (1)

A reversible rotation type DC motor having no built-in brake function, a drum connected to the DC motor via a speed reduction mechanism, a wire rope wound around the drum and holding a lifted device, and the wire rope A lifting switch characterized by having a detection switch for detecting a slackened state and a braking circuit for instantaneously short-circuiting the terminals of the DC motor through a resistor when the detection switch is operated in a state where the device to be lifted is lowered. apparatus.

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