JPS598623B2 - elevator elevator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a device for braking an emergency drive motor of an elevator.

A conventional emergency braking system for a DC elevator is shown in FIG.

In the figure, 1 is an armature of a DC generator (field omitted) driven by an induction motor (not shown), 2 is an armature of a DC motor supplied with power from armature 1 (field omitted),
3 is a discharge resistor connected in parallel to armatures 1 and 2; 4b is a main circuit electromagnetic contactor contact that closes when an emergency braking command is issued; 4a
is the same contact that opens, 5 is the sheave of the hoisting rock driven by the armature 2, 6 is the main rope wrapped around the sheave 5,
A heel 1 and a counterweight 8 are respectively connected to both ends thereof.

9 is a brake wheel fixed to the shaft of the armature 2; 10 is a brake shoe disposed facing the outer periphery of the brake wheel; 1;
1 is coupled to the brake shoe 10 and 11. 12 is a pressing spring that presses the iron core 11 toward the brake shoe 10;
13a and 13b are wound around the iron core 11 and when biased, push the iron core 11 against the force of the spring 12 and push the brake shoe 1.
This is a brake coil that moves in a direction away from 0.

Prior to starting the armature 2, the brake coils 13a, 13
b is energized, and the movement of the iron core 11 causes the brake shoe 10 to separate from the brake wheel 9.

Further, the contact 4a is closed and the contact 4b is opened in advance.

The armature 1 generates a variable voltage by controlling its magnetic field, and this voltage is applied to the armature 2.

This causes the armature 2 to rotate and the heel 7 to travel via the sheave 5.

If some kind of failure occurs and an emergency braking command is issued while car 7 is running, contact 4a opens and armature 2 switches to armature 1.
be cut off from

Then, instead, the contact 4b is closed and the discharge resistor 3 is connected, so that the armature 2 generates a dynamic braking force.

At the same time, the brake coils 13a and 13b are also deenergized, and the brake shoe 10 presses the brake wheel 9 to apply a frictional braking force.

These two braking forces cause the armature 2 to rapidly decelerate and the car 7 to stop.

Generally, the maximum deceleration in the above case occurs at the moment of emergency braking, that is, when the dynamic braking force is at its peak.

At this time, the dynamic braking force and the frictional braking force are set so that the sum of them is the maximum value within a range that does not cause slippage between the main rope 6 and the sheave 5.

If the above-mentioned braking force is excessive, slippage will occur between the main rope 6 and the sheave 5, but once slipping occurs, the car 7 will not decelerate in a short period of time since dynamic friction is smaller than static friction. become.

This means that the deceleration and stopping distance has increased beyond a predetermined distance.

Especially in emergency braking when using a shortened stroke shock absorber,
Before the car 7 collides with the buffer, the speed of the car 7 must be reduced below the maximum collision speed of the buffer.

However, if the main rope 6 slips as described above, the car 7 will collide at a speed that exceeds the maximum collision speed of the buffer.
It is a danger.

Conventionally, this dynamic braking force was selected so that the main rope 6 would not slip at the moment of emergency braking when the car 7 was raised without a load or lowered with an overload.

However, the deceleration of the heel 7 at the limit at which the main rope 6 slips is not the same when ascending with no load and descending with an overload, as shown in FIG. 2.

In the figure, line A indicates the limit allowable deceleration of the main rope 6,
When the car 7 is ascending and descending, it is desirable that the deceleration due to the emergency braking force (hereinafter referred to as braking deceleration) approaches line A and is equal to or less than line A at all loads.

However, if the braking deceleration is set to the allowable deceleration Af during overload descent, the braking deceleration during no-load ascent will be greater than the allowable deceleration An, and the main rope 6 will slip, as shown by line B. .

Therefore, as shown by the broken line C, the allowable deceleration An was set at the time of no-load ascent.

However, in this case, the braking force during overload descent is weak, and the stopping distance of the car 7 becomes too long, which is dangerous.

This invention improves the above-mentioned drawbacks and provides an emergency braking device for an elevator that can obtain sufficient braking force under all loads while the elevator is ascending and descending within a range that does not cause the main rope to slip. The purpose is to

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

In the figure, 15 is a diode that short-circuits a part of the discharge resistor 3.

While car 1 is rising, an emergency braking command is issued and contact 4a
When the contact 4b is opened and the contact 4b is closed, the polarity of the voltage generated by the armature 2 is as shown by (+) and (→).

Therefore, at this time, the diode 15 is not conductive,
As in the case of FIG. 1, if the braking deceleration is set to the allowable deceleration An during no-load ascent, the characteristics will be as shown by the broken line D1 in FIG.

Next, when the emergency braking command is issued while the car 7 is descending, the polarity of the voltage generated in the armature 2 is opposite to that shown in FIG. 3.

Therefore, the diode 15 becomes conductive, a part of the discharge resistor 3 is short-circuited, and the dynamic braking force of the armature 2 becomes larger than when rising.

The braking deceleration at this time is the allowable deceleration Af during overload descent.
If it is set to , the characteristics will be as shown by the broken line D2 in FIG.

In this way, by changing the braking force depending on the traveling direction of the car 7, a braking deceleration that always approaches the allowable deceleration and is equal to or less than the allowable deceleration can be obtained.

FIG. 5 shows another embodiment of the present invention, in which 16 is a short-circuiting electromagnetic contactor connected in series with a diode 15;
6a is its normally open contact.

When the car 7 is rising, the contactor 16 is not energized by the action of the diode 15, and the contacts 16a are open.

Moreover, since the contactor 16 is energized and the contact 16a is closed at the time of descent, a part of the discharge resistor 3 is short-circuited.

Therefore, the characteristics of this braking deceleration are equivalent to those shown in FIG.

As explained above, in this invention, the dynamic braking force applied to the DC motor that drives the car is changed as the car travels in a predetermined direction, so that the main rope is maintained under all loads when the elevator is ascending and descending. Sufficient braking force can be obtained within a range that does not cause slippage.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a conventional elevator emergency braking device, FIG. 2 is a characteristic diagram of braking deceleration, and FIG. 3 is a main circuit diagram showing an embodiment of an elevator emergency braking device according to the present invention. FIG. 4 is an explanatory diagram of the characteristics of braking deceleration according to FIG. 3,
FIG. 5 is a main circuit diagram showing another embodiment of the invention. DESCRIPTION OF SYMBOLS 1...DC generator armature, 2...DC motor armature, 3...Discharge resistance, 4a, 4b.
... Main circuit magnetic contactor contact, 5 ... Sheave, 6 ... Main rope, 7 ... Car, 8 ...
...Balance weight, 15...Diode. In addition, the same parts or corresponding parts in the figures are indicated by the same reference numerals.

Claims (1)

[Claims] 1. In a DC motor that is connected to a DC power source and drives a car, a discharge resistor is connected in parallel to the motor to apply a dynamic braking force to the motor, and when it is detected that the car is traveling in a predetermined direction, An emergency braking device for an elevator, comprising a shorting element that shorts out a part of a discharge resistor.