JPH052548Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to a double hoist and is intended to prevent the starting current from becoming excessive.

B. Summary of the invention The present invention is a double hoist that prevents an increase in starting current by staggering the starting of the motor of the double hoist.

C. Prior Art A conventional double hoist will be explained based on FIG.
A double hoist is one in which two hoists 1 and 2 are integrally connected, and each hoist 1 and 2 is formed of a winding drum 3 and 4 and motors 5 and 6 that rotationally drive the winding drums 3 and 4, respectively. One end of the wire rope 8 wound around the load dock 7 is wound up and let out by the hoist 1, and the other end side is wound up and let out by the hoist 2. Therefore, when hoists 1 and 2 are operated together, load block 7
is raised and lowered at the same speed as the circumferential speed of the winding drums 3 and 4, and when only one hoist is operated, the load block 7 is raised and lowered at half the circumferential speed.

D. Problems to be Solved by the Invention Squirrel cage induction motors are generally used as the motors 5 and 6, and a direct start method is adopted as the starting method. Therefore, at the time of starting, a starting current of 5 to 6 times the rated value flows through each motor. Therefore, when the two motors 5 and 6 are started at the same time, the rated value will not be applied to this double hoist.
An extremely large starting current of 10 to 12 times flows.

As mentioned above, a large starting current flows in the conventional double hoist, so the capacity of the electricity supply system of the factory where the double hoist is installed must be large. For example, the capacity of the power transformer installed at the factory must be increased, and the power cable must be made thicker. Under these circumstances, in new factories, the electricity supply system is designed to meet the above requirements, so there are few problems, but when adding a double hoist to an existing factory, the capacity of the power transformer is insufficient and it becomes necessary to run two motors at the same time. There is also a possibility that a situation may arise in which the engine cannot be started.

Note that Japanese Utility Model Publication No. 36-8929 discloses a technique in which only one motor is driven in the upper limit range and the lower limit range. To explain this with reference to FIG. 4, the motor 5 can be driven when the roadblock 7 is in the _l1 range, and the motor 6 can be driven when the roadblock 7 is in the _l2 range. . Therefore, only motor 5 operates between lower limit ranges L ₃ and L ₄ ,
Since only the motor 6 operates between the upper limit ranges L ₁ and L ₂ , the above-mentioned problem does not occur in the upper limit range and the lower limit range. However, since the motors 5 and 6 are started at the same time between _L2 and _L3 , there still remains the problem that a large starting current flows.

In view of the above-mentioned prior art, the present invention aims to provide a dual hoist in which the starting currents of the respective motors do not overlap at the time of starting.

E. Means for Solving the Problems The configuration of the present invention that achieves the above object is that in a double hoist, when the drive switch is turned on, the motor of one hoist starts immediately, but the motor of the other hoist starts. The present invention is characterized in that it includes a control device that controls the motor to start after the start of one motor is completed.

F. Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a plan view showing an embodiment of the present invention, and FIG. 2 is a front view thereof. As shown in both figures, the double hoist 10 according to this embodiment includes two hoists 1
1 and 21 are connected together. The hoist 11 has a winding drum 12, a high-speed motor 13, a high-speed electromagnetic brake 14, a slow-speed motor 15, a slow-speed electromagnetic brake 15, and an upper and lower limit switch 17. Similarly, the hoist 21 has a winding drum 22.
, high-speed motor 23, and high-speed electromagnetic brake 24
, a slow speed motor 25 , and a slow speed electromagnetic brake 26
and an upper and lower limit switch 27. On the other hand, one end of the wire rope 31 wound around the load block 30 is attached to the hoist 11.
At the same time, the other end side is wound up and unwound by a hoist 21. Motor 13,1
Reference numerals 5, 23, and 25 are squirrel cage induction motors, which are started using the direct starting method.

The high-speed motors 13 and 23 rotate the winding drums 12 and 22 at high speed to take up and pay out the wire rope 31 and move the load block 30 up and down. At this time, the starting timing of the high-speed motors 13 and 23 is as described in detail later with reference to FIG.
It is shifted. Note that the stops are performed at the same time.
Further, the high-speed motors 13 and 23 are braked by high-speed electromagnetic brakes 14 and 24.

The slow speed motors 15 and 25 are started and stopped at the same time, and the winding drums 12 and 22 are slowly rotated to wind up and pay out the wire rope 31, so that the wire rope 31 is wound on one winding drum in a biased manner. Then, adjust the wire rope 31 so that the same amount of wire rope 31 is wound around both winding drums 12 and 22, and align the origin. The slow speed motors 15 and 25 are braked by slow speed electromagnetic brakes 16 and 26.

The upper and lower limit switches 17, 27 stop the motors 13, 23, 15, 25 when the load block 30 reaches the upper or lower limit. This improves safety.

Next, referring to FIG. 3, the high-speed motors 13, 23
The braking device 40 and its braking operation will be described below.
As shown in FIG. 3, the high-speed motors 13 and 23 of the hoists 11 and 12 are controlled to start and stop by a control device 40 comprised of a sequence circuit. This control device 40 is a relay coil
MC11, MC12, MC21, MC22, R1, R2 and relay contacts mc11, mc12, mc21-1, mc21-2,
It has mc22-1, mc22-2, r1, r2, timer coils T1, T2, timer contacts t1, t2, an up switch USW, and a down switch DSW. Further, R, S, and T are power supply lines to which three-phase alternating current is supplied. Furthermore, the above coils T1, T2 and contacts
The delay time of the timer formed by t1 and t2 is longer than the time from when the high-speed motor 23 starts to enter steady operation. Specifically, the timer delay time is 0.3
~0.5 seconds or more.

The operation of the sequence circuit shown in FIG. 3 will be explained. When the lift switch USW, which is the drive switch, is turned on, coil MC21 is energized, which causes the contact
mc21-1 and mc21-2 are input. Then, by turning on contact mc21-1, high-speed motor 23
is started, and the timer coil T1 starts operating as a timer by turning on the contact mc21-2. After a certain period of time has passed from this point, the coil
T1 becomes energized and contact t1 is closed. At the time when the contact point t1 is closed in this manner, the high-speed motor 23 is in steady operation. Then, when the contact t1 is closed, the coil R1 is energized and the contact r1 is closed, and the coil MC11 is energized and the contact MC11 is closed. The high speed motor 13 is started by closing this contact mc11. As a result, the motors 23 and 13 are started with their starting timings shifted and wind up the wire rope 31. Furthermore, when the switch USW is opened, contacts mc21-1 and mc11 are opened at the same time.
High speed motors 23 and 13 stop simultaneously.

On the other hand, the lowering switch which is the drive switch
When the DSW is turned on, the coil MC22 is excited, which turns on the contacts mc22-1 and mc22-2. Then, the high-speed motor 23 is started in the opposite direction to the previous time by turning on contact mc22-1, and the timer coil is started by turning on contact mc22-2.
T2 starts working as a timer. After a certain period of time has elapsed from this point, the coil T2 becomes excited and the contact t2 is closed. When the contact point t2 is closed in this way, the high-speed motor 23 is in steady operation. Then, by closing contact t2, the coil
R2 is energized, contact r2 is closed, and coil MC12
is energized and contact mc12 is closed. This contact
By turning on mc12, the high-speed motor 13 is started in the opposite direction from the previous time. As a result, the motors 23 and 13 are started with their starting timings being shifted, and the wire rope 31 is let out. Note that when the switch DSW is opened, the contacts mc22-1 and mc12 are simultaneously opened, and the high-speed motors 23 and 13 are stopped at the same time.

It should be noted here that the starting timing difference between the high-speed motors 13 and 23 is as short as 0.3 to 0.5 seconds, so the wire rope 31 will not be excessively wound up or unwound with respect to one hoist, and mechanically The hoists 11 and 21 operate almost simultaneously and the wire rope 3
Perform winding and unwinding of step 1.

As described above, in this embodiment, the high-speed motor 13 is started after the high-speed motor 23 enters steady operation.
Therefore, assuming the rated current of one motor, when the high-speed motor 13 is started, the starting current is 5I to 6I, and the current of the high-speed motor 23 is I, so the double hoist has 6I to 7I. All it takes is a current of . By the way, high speed motor 13,2
If 3 are started at the same time, a current of 10I to 12I will flow in.

G. Effects of the Invention As specifically explained in conjunction with the embodiments above, according to the present invention, since the starting of the motor is delayed, the current at the time of starting can be suppressed. Therefore, the power cable that supplies power to the double hoist can be thin, and the transformer capacity for the factory power supply can be small.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a front view thereof, FIG. 3 is a circuit diagram showing a sequence circuit of this embodiment, and FIG. 4 is a configuration diagram showing a prior art. In the drawing, 10 is a double hoist, 11 and 21 are hoists, 12 and 22 are winding drums, 13 and 23 are high-speed motors, 30 is a load block, 31 is a wire rope, and 40 is a control device.

Claims (1)

[Claims for Utility Model Registration] It is constructed by connecting two hoists each having a winding drum and a motor for rotationally driving the hoist, and the motor is an induction motor that is started by a direct start method, and In a double hoist where one end of the wire rope wound around the load block is wound up and unwound by one hoist, and the other end of the wire rope is wound up and unwound by the other hoist, the drive switch is turned on. The dual hoist is characterized in that it is equipped with a control device that controls the motor of one hoist to start immediately, but the motor of the other hoist to start after the starting of one motor is completed.