JPS6047193B2 - Elevator safety device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety device for an elevator driven by a DC motor.

Some elevators that use a DC motor for driving are configured so that the field of the motor is de-energized when the motor is stopped.

This is done to save power since the field of the electric motor consumes a large amount of power. However,
In such a case, when the elevator is stopped, if for some reason the brakes do not generate the specified braking torque, or if the brake coil is energized and the brake is released due to an accident such as contact with external electric wires, If the elevator car is unloaded, it will travel upwards as it is pulled by the counterweight.

Also, if the car is heavily loaded, it will run downward. Then, as mentioned above, since the field of the electric motor is deenergized, the dynamic braking torque is applied, and the car accelerates freely until the car or counterweight hits the shock absorber beyond its maximum allowable collision speed. This will result in a collision and damage to various parts of the elevator. The present invention aims to improve the above-mentioned problems and provides an elevator safety device that prevents the car from freely accelerating even if the brake torque decreases while the elevator is stopped.

An embodiment of the present invention will be described below with reference to FIG.

In the figure, 1 is an elevator car, 2 is a counterweight, 3 is a main rope, 4 is a sheave, 5a is an armature of a DC motor that drives the sheave 4, 5b is a field magnet, 6 is a friction brake, 6a
is the brake coil; when the brake coil 6a is deenergized, the sheave 4 is restrained by the force of the spring, and when the brake coil 6a is energized, the sheave 4 is released against the force of the spring. Snow.

7 is a three-phase AC power supply, 8 is a thyristor converter, 9 is a discharge resistor, 10 is a main circuit contactor, 10a is its normally open contact, 1
b is also a normally closed contact, 11 and 12 are power transformers, 13
is a field energizing thyristor converter, 14 is a diode, 1
5 is a brake contactor contact that closes when starting and opens after 5 stops; 16a and 16b are starting circuit output relay contacts that close when starting and open when stopping; 17 is a point on the field energizing thyristor converter 13. An arc circuit, 18 is a speedometer generator, 19 is a running detection device, 19a is its output contact, 20 is a speed command generation device, and 21 is an ignition circuit.

When the elevator starts, the starting circuit output relay contacts 16a and 16b are opened, the field energizing thyristor converter 13 is ignited by the ignition circuit 17, and the motor field 5b is energized. At the same time, main circuit contactor 10 is energized, contact 10a is closed and contact 10b is open. This results in
Variable voltage DC power converted by a thyristor converter 8 is supplied to the armature 5a. The brake contactor contact 15 then closes, the brake coil 6a is energized, and the friction brake 6 releases the sheave 4. Now, the armature 5a rotates and the car 1 starts running. When the car 1 runs, the speedometer generator 18 emits an output, and based on this and the output of the speed command generator 20, the ignition circuit 21 controls the thyristor converter 8, and the armature 5a of the car 1 is activated. Speed is automatically controlled with high precision. Furthermore, when the speedometer generator 18 outputs an output, the speed detection device 19 operates and the contact 19a opens, but since the contact 16a is already closed, it does not affect the ignition circuit 17. . When the output of the thyristor converter 8 decreases and the speed of the armature 5a decreases and the car 1 stops, the brake contactor contact opens, the brake coil 6a is deenergized, and the friction brake 6 moves the sheave 4. to bound.

Then, the starting circuit output relay contact 16b is opened, the main circuit contactor 10 is deenergized, the contact 10a is opened and the armature 5a is disconnected from the thyristor converter 8! be done. At the same time, contact 16a is also opened. At this time, since the car 1 is stopped, the speedometer generator 18 and the running detection device 19 do not output any output, and the contacts 19a are also open. The ignition circuit 17 therefore ceases ignition of the thyristor converter 13 and
The electric motor 3 field 5b is deenergized and power consumption is saved.
Now, when the car 1 is stopped, if for some reason the brake 6 does not generate the specified braking torque, or if an accident such as contact between external electric wires causes the contact 15 to close and the brake coil 6a to be energized, As mentioned above, basket 1 is equal to counterweight 2.
It starts to move upward or downward depending on the weight difference between the two.
At this time, the traveling detection device 19 operates and the contact 19a closes, so the ignition circuit 17 operates, the thyristor converter 13 is ignited, and the motor field 5b is energized. Therefore, a current flows through the armature 5a through the circuit 5a-9-10b-5a, and a dynamic braking torque acts on the car 1, so that the acceleration of the car 1 is suppressed and the car 1 or the counterweight 2 is connected to the shock absorber (not shown). The speed will not exceed the rated speed when a collision occurs. The shock absorbers are designed to prevent damage to the elevator even if the car crashes at speeds up to 115% of its rated speed, so there is no danger. In addition, a brake switch (not shown) detects that the brake 6 releases the sheave 4.
It is also possible to provide a switch such that the motor field 5b is energized when this switch is operated.

Even such a configuration is sufficiently effective against the brake release due to the above-mentioned external electric wires coming into contact with each other. FIG. 2 shows another embodiment of the invention.

In the figure, 10c is a normally closed contact of the main circuit contactor 10, 10d is also a normally open contact, 19b is a normally open contact of the running detection device 19, 22 is a discharge resistor short-circuit contactor, 22a is its normally open contact, Reference numeral 3 denotes a time-limited return type time relay that operates immediately when energized and returns after a certain period of time when de-energized, and 23a is its normally closed contact.

The rest is the same as in FIG. Note that the ignition circuit 17 and the discharge resistor short-circuit contactor 22 function as a safety circuit.

While the elevator is stopped, the contact 19b is open, so the discharge resistor short-circuit contactor 22 is deenergized and the contact 22 is open.

While car 1 is running, timed relay 2 is activated by closing contact 10d.
3 is energized, and the contact 23a is opened. When emergency braking is applied for some reason while car 1 is running, contact 10d
is opened and the time relay 23 is deenergized, but since the point 23a is open for several seconds, the discharge resistor shorting contactor 22 is not energized during this time. The time limit of this time limit relay 23 is
The time is selected to be longer than the normal time for car 1 to actually stop after the emergency stop command is issued. Therefore, in the case of the emergency stop, the car 1 is decelerated at a deceleration determined by the value of the discharge resistor 9, and an excessive deceleration does not occur. Now, as described above, when the braking torque of the brake 6 is lost during a stop, the car 1 begins to move, the travel detection device 19 is activated, and the motor field 5b is energized by the operation of the ignition circuit 17.

At the same time, contact 19b is also closed. Since the contact 10c is already closed and the contact 10d is open, the time relay 23 has returned and the contact 23a is closed. Therefore,
In the circuit 19b-23a-10c-22, the discharge resistor shorting contactor 22 is energized, the contact 2a is closed, and the discharge resistor 9 is shorted. As a result, at low rotation speeds, the current passing through the armature 5a becomes stronger than when it passes through the discharge resistor 9 in the state set for the emergency stop command, and the dynamic braking torque also becomes large. The speed is 10~ of the rated speed.
It can be suppressed by 20% or less. That is, the emergency stop command is issued when the car 1 abnormally approaches the terminal floor at the rated speed, or when the speed exceeds the rated speed, and the speed of the car 1 may be high.

On the other hand, when the motor field 5b is energized with a constant current, the DC motor has a rotational speed that is approximately proportional to the voltage of the armature 5a.

Therefore, the voltage of the armature 5a when an emergency stop command is issued is often at a high value, and the discharge resistor 9 limits the current of the armature 5a against this high voltage to a range that does not impair rectification. This is set under the conditions that the main rope 3 and the sheave 4 do not slip due to excessive braking torque.

That is, since it is set for high speed rotation, the braking torque is small at low speed rotation. By the way, when the stopped car 1 starts moving due to imbalance with the counterweight 2, the number of rotations starts from zero value.

Therefore, the voltage generated by the armature 5a also becomes zero.
Therefore, if the discharge resistor 9 is used at the value set for the emergency stop command, sufficient braking torque will not be obtained until the car reaches high speed, and the car 1 will be accelerated until it balances out the unbalanced torque. However, since the car must originally be stopped, it is desirable that the speed of car 1 be as low as possible.
In the embodiment shown in FIG. 2, the discharge resistor 9 is short-circuited as an extreme case. As a specific example, Ra: resistance value of armature 5a and brush R: value of discharge resistance 9 (=10r'a) E: voltage of armature 5a at rated speed e: armature when brake 6 is defective 5a voltage (set value) 1: When the armature 5a current is set to match the unbalanced torque, the following equation holds true.

Therefore, e/E″.0.1, which is approximately 10% of the rated speed.
becomes.

Note that this is not limited to the case where the discharge resistor 9 is short-circuited.

As mentioned before, the buffer is used when car 1 is at the rated speed of 11
The speed of car 1 was set to 5%, considering that it can be handled even if it reaches 5%, and that short-circuiting the armature 5a without using a resistor would cause a large current to flow in the event of an accident, causing great damage. It is desirable to set the discharge resistance 9 to a predetermined value smaller than that for the emergency stop command by allowing the discharge resistance to rise slightly more than in the case of a short circuit. FIG. 3 also shows another embodiment of the present invention, which is applied to a Ward Leonard type elevator.

In the figure, 24 is an induction motor, and 25 is an armature of a DC generator driven by the induction motor 24 (the field is omitted). While car 1 is stopped, the voltage generated by the generator is maintained at zero.

This is explained in the 126th edition of ``Recent Elevators and Escalators'' (8th edition published on September 15, 1939) by Takeo Kimura.
It is well known as described on page 12, top 12.
Since the generator is not generating voltage while the car 1 is stopped, the motor is not driven by the generator even if the contact 10a is closed. Conversely, when the braking torque of the brake 6 is lost during a stop and the armature 5a of the electric motor rotates, power is generated. At this time, the main circuit contactor 10 is energized in the circuit 19b-23a-10, the contact 10a is closed, and the contact 10a is closed.
A circuit of 10a-25-5a is formed. That is, during the stoppage, the armature 25 of the generator functions as a substitute for the discharge resistor 9. Since the armature resistance of the DC motor is very small, the current passing through the armature 5a becomes stronger, similar to the case in Figure 2, and the dynamic braking torque becomes large.
The speed of can be suppressed. As described above, this invention is designed so that when the car moves due to a decrease in the braking torque of the brake while the car is stopped, the discharge resistance value set for emergency stop is reduced to generate a large generated braking torque even at low speed rotation. Therefore, if an emergency stop command is issued at high speed, the car can be decelerated without impairing commutation, and if the car starts moving due to a brake failure, it can be prevented from accelerating, and the car can be prevented from reaching the shock absorber at a critical speed. Collision can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of an elevator safety device according to the present invention, and FIGS. 2 and 3 are block diagrams showing other embodiments of the present invention. 1...basket, 4...sheave, 5a...
... Armature of DC motor, 5b ... Same left field, 6 ... Friction type brake, 6a ... Brake coil, 8 ... Thyristor conversion Vessel, 9.
...Discharge resistance, 10...Main circuit contactor,
13... Thyristor converter for field energization, 15.
・Brake contactor contacts, 16a, 16b... Starting circuit output relay contacts, 17... Starting circuit, 1
8... Generator for speedometer, 19... Running detection device.

Claims (1)

[Claims] 1. In an elevator that is driven by a DC motor and applies a dynamic braking torque to the motor through a discharge resistor during an emergency stop of the motor, and operates a brake to stop the motor when the car is stopped, a travel detection device that is activated when the car moves in an operating state; an activation signal from the travel detection device reduces the discharge resistance to a value at the time of the emergency stop;
A safety device for an elevator, comprising a safety circuit that connects the reduced discharge resistance to an armature of the electric motor to generate a dynamic braking torque.