SU775044A1 - Crane mechanism overload protection device - Google Patents

Description

one

The invention relates to the field of hoisting and transport machinery, namely, devices for protecting crane mechanisms against overload / and can be used, for example, on jib floating cranes.

A device for protecting crane mechanisms against overload is known, which contains a force sensor, a comparator and a TI relay. The known device is equipped with an assembly that allows testing electrical circuits of a relay and a comparator.

A disadvantage of the known device is the limited functionality: the possibilities that prevent the load from dropping when one of the cables breaks.

It is also known a device for protecting crane mechanisms against overload, comprising force sensors connected through upper and lower comparators to corresponding upper and lower level relays, as well as sling relief units {2j.

A disadvantage of the known device is comparatively low: in reliability due to the lack of means allowing to check the electrical circuits of the comparators, the upper and lower level relays, and the reset blocks of the slings.

The purpose of the invention is to increase the reliability of the device.

This is achieved by the fact that the proposed device is equipped with a power relay, the inverse output of which is connected in series with comparators.

10 high and low levels and with high and low relays, time relays and check relays, the inverse outputs of the high and low relays through the power relay output with sequentially switched on check relays, the inverse output of the time relays and sling drop units, while the blocks resetting the slings through the time relay output is connected to the inverse outputs of the upper and lower level relays, and the output of the test relay is connected in series with the time relay, the second output of which is connected to the pair, allele to the output of the test relay, and the third.

25 output - parallel to the inverted output of the power relay.

The device can be equipped with an alarm unit connected to the twisted time relay output.

FIG. 1 shows a functional diagram of the proposed device; FIG. 2 is an electrical diagram of a part of the functional diagram of the device;

The device for protecting the crane mechanisms against overload contains sensors 1 and 2 of force connected through amplifiers 3 and 4 to comparators 5, 6 and 7, 8 upper and lower levels and relays 9, 10 and 11, 12 upper and lower levels. Comparators 5.6 and 7.8 are connected to blocks 13 and 14 of the programs. The device is equipped with a power relay 15, the inverse output 16 of which is connected in series with comparators 5-8 and relay 9-12. The inverse outputs 17-20 of relay 9-12 through the output 21 of relay 15 and the output 22 of intermediate relay 23 are connected to the series-connected check relays 24, the inverse output 25 of time relay 26 and the sling-reset units 27 and 28, which in turn are connected to the output 29 of the relay 23 and the output 30 of the relay 26. The output 31 of the relay 24 is connected in series with the relay 26, the second output 32 of which is connected in parallel with the output 31, and the third output 33 of the relay 26 is connected in parallel with the inverse output 16 of the relay 15. Relays 15, 23, 24 and 26 and the reset blocks 27 and 28 are connected to the power source via switch 34.

The device can be equipped with an alarm unit connected to the fourth output 35 of the relay 26 and the inverse output 36 of the relay 23. The fifth output 37 of the relay 26 is intended for switching the blocks 27 and 28 from the series connection when checking for parallel when lifting the load. Relays 15, 23, 24 and 26 form a unit 38 for checking electrical circuits.

The device works as follows.

When the key 34 is closed, the relay 15 is turned on. the output 16 breaks the power supply circuit of the relay 9-12, and the output 21 connects the power supply to the relay 23, which supplies power to the serially connected blocks 27 and 28 for the release of the slings and the relay 24. The latter turns on and through the output 31 turns on the relay 26, which disconnects from the source

powering the relay 24 connects to the power source the relays 9-12, and then turns blocks 27 and 28 parallel to each other. Output 35 of the relay 26 signals the normal operation of the elements of the device, the relay 23 is turned off, and blocks 27 and 28 are disconnected from the source nutrition

The operator closes the key 34 to check the operation of the device elements when lifting the load close to the limit when all the crane lifting mechanisms are working and all the comparators 6 and 8 of the lower level have operated (with an effort in the cargo cable about 10-20% of the nominal force). Making sure that the unit 38 is functioning, the operator continues to lift the load. In case of accidental breakage of the cargo cable, the corresponding comparator 6 or 8 of the lower level and relay 10 or 12 will operate, this activates the relay 23, which connects the blocks 27 and 28 to the power source, and the load is discharged, which prevents the load the cable remained intact.

Claims (2)

Invention Formula A device for protecting crane mechanisms from overload, containing force sensors connected through upper and lower level comparators to upper and lower level relays, as well as sling relief units, which, in order to increase reliability, are equipped with a relay power supply, the inverse output of which is connected in series with the upper and lower level comparators and with the upper and lower level relays, time relays and test relays, and 1 higher outputs of the upper and lower levels are connected via a power output relay but the test relays are turned on, the inverse output of the time relay and the sling discharge units, the sling discharge units through the time relay output are connected to the inverse outputs of the upper and lower levels, and the output of the test relay is connected in series with the time relay, the second output of which is connected in parallel with the output the test relay, and the third output is parallel to the inverse output of the power relay. 2. A device according to claim 1, characterized in that it is provided with an alarm unit associated with a fourth time relay output. Sources of information taken into account in the examination 1. USSR author's certificate No. 578262, cl. B 66 C 15/06, 16.01.75. 2. USSR author's certificate on application 1 2507728/11, cl. In 66 C 23/88, 07/13/77 (prototype). R 3V / Jei one J8 27 SI    f 5 IJ uj a  h-1 1i