JP2005096934A - Brake controller for elevator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a safe and inexpensive brake controller for an elevator capable of preventing occurrence of secondary failure of a brake coil or a power supply device without increasing size of the brake coil and the power supply device when a current detector or an A/D converter causes failure and preventing possibility that a passenger is shut into the elevator. <P>SOLUTION: This brake controller is provided with a switching element 13 for a step-down chopper for controlling current of the brake coil 10 by a PWM 14, the current detector 15 for detecting current of the brake coil 10, the A/D converter 16 for converting output of the current detector into a digital signal, a current controller 18 for outputting a voltage corresponding to difference between output of the A/D converter and a command current value 17 to the PWM, and a switching device 21 for switching voltage output to the PWM from the current detector to a command value 22 of predetermined voltage when detecting abnormality of the current detector or the A/D converter. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an elevator brake control device.

FIG. 4 shows a general configuration of a conventional elevator brake control device.
As shown in this figure, an elevator car 1 is suspended in a slidable manner with a counterweight 4 by a main rope 3 wound around a sheave 2 of a hoisting machine, and is driven by a hoisting motor 5.
The brake drum 6 is generally installed on a shaft that connects the hoisting motor 5 and the sheave 2, supports one end of the fixing portion 8 of the brake shoe 7, and provides a tension spring 9 at the other end, thereby providing the brake shoe 7 is always pressed against the brake drum 6 to obtain a braking force by a frictional force.

When the elevator is started, an electric current is passed through the brake coil 10 constituting the electromagnet, the armature 11 provided in the fixed portion 8 is overcome by the tension spring 9 and sucked, and the brake shoe 7 is pulled away from the brake drum 6 to release the braking force. .
At this time, it is detected that the brake contact 12 is entered by the fixing portion 8 and the braking force is released. When braking again, the brake coil 10 is de-energized and the brake shoe 7 is pressed against the brake drum 6 by the tension spring 9 to obtain a braking force.

Further, a step-down chopper switching element 13 is connected in series to the brake coil 10, and ON / OFF control is performed by a signal given from the PWM 14, so that a current flowing through the brake coil 10 is controlled.
The brake current is controlled by converting the current value of the brake coil 10 detected by the current detector 15 into a digital value by the A / D converter 16, and the detected value matches the preset brake current command value 17. Thus, a voltage command value is output from the current controller 18 to the PWM 14, and the PWM 14 turns on / off the step-down switching element 13 based on the voltage command value to control the current flowing through the brake coil 10. .

  The brake current command value 17 can be set to a large current value before the brake armature 11 is attracted, and the armature 11 can be retained after suction, in order to reduce the thermal protection or power capacity of the brake coil 10. The current value is set to a small value. (For example, refer to Patent Document 1).

Japanese Utility Model Publication No. 5-69041 (paragraphs 0002-0008, FIGS. 1 to 5)

  Since the conventional elevator brake control apparatus is configured as described above, as shown in FIG. 5 (a), during traveling, the current detector 15 or the A / D converter 16 fails due to some cause at time t. Even if the current detection value indicated by the broken line becomes 0 at the time t, the current command value retains a predetermined value as indicated by the solid line, so the current controller 18 generates a current corresponding to the difference. Since an excessive voltage command as shown in FIG. 5C is output to the PWM 14 in an attempt to flow, the actual value of the current flowing through the brake coil 10 increases at the time t as shown in FIG. When the mileage is long, the brake coil 10 may be burned out due to a temperature rise or a failure due to an overload of the power supply device, and the failure may be expanded.

  In order to avoid this problem, a method of increasing the capacity of the brake coil 10 or the power supply device has been conventionally used. However, the brake or the power supply device becomes large, which is not preferable in terms of space saving and cost. In addition, there is a method of stopping the elevator when a failure of the current detector 15 or the A / D converter 16 is detected. However, in this case, there is a problem that passengers are trapped.

  The present invention has been made in order to solve the above-described problems. When the current detector or the A / D converter breaks down, the brake is applied secondarily without enlarging the brake coil or the power supply device. An object of the present invention is to provide a safe and inexpensive elevator brake device that does not cause a failure of a coil or a power supply device and does not cause a passenger to be trapped.

  The elevator brake device according to the present invention includes a spring device that constantly presses the brake shoe against the brake drum of the elevator to generate a braking force, and the brake shoe against the spring device when biased. In an elevator brake control device having a brake coil that is separated from the drum and releases braking force, a step-down chopper switching element that controls the current of the brake coil by PWM, and a current detector that detects the current of the brake coil; An A / D converter that converts the output of the current detector into a digital signal; a current controller that outputs a voltage corresponding to the difference between the output of the A / D converter and a command current value to the PWM; When an abnormality is detected in the current detector or A / D converter, a voltage output to the PWM is output from the current detector. It is obtained by a switching device for switching the command value of the voltage.

In the elevator brake device according to the present invention, when the current detector or the A / D converter fails, the current feedback control is switched to the feedforward voltage control, so that an excessive current flows through the coil. It is possible to prevent secondary failure of the power supply device or burning of the brake coil.
In the present invention, since the feedforward voltage command value is set using the resistance value of the brake coil estimated from the coil temperature of the brake coil, it is more appropriate without being affected by the change in the resistance value of the brake coil. A correct voltage command value can be set.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of the first embodiment. In this figure, the same or corresponding parts as in FIG. A difference from FIG. 4 is that a switching device 20 is provided that detects an abnormality in the current detector 15 and the A / D converter 16 and switches a command voltage value for PWM to a command value of a predetermined voltage at the time of detection.

  That is, a changeover switch 21 is provided between the PWM 14 and the current controller 18 and the movable contact 21a is always connected to the current controller 18 side. However, due to a failure of the current detector 15 or the A / D converter 16. When the current feedback value becomes 0, the movable contact 21a is disconnected from the current controller 18 by the operation of the switching device 20, and switched to the voltage command value 22 side set in advance to the predetermined voltage Vs. The predetermined voltage of 22 is applied to the PWM 14.

  The flow of operation at this time is shown in FIG. That is, FIG. 2A is the same as FIG. 5A, and a failure occurs in the current detector 15 or the A / D converter 16 for some reason at time t, and the current detection value indicated by the broken line is at time t. This shows a state of 0. At this time, the switching device 20 switches the movable contact 21a of the changeover switch 21 to the voltage command value 22 to switch to feedforward voltage control as shown in FIG. As shown in FIG. 5B, since the slight change is maintained, the above-described conventional problems can be prevented.

Further, Vs of the voltage command value 22 is obtained by using the resistance value R of the brake coil 10 and Is of the current command value 17 which are measured in advance.
Vs = R x Is + α (α = tolerance) (1 set)
Set as. Vs must be set so that the brake can be held sufficiently.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a block diagram showing the main part of the second embodiment. In this figure, the same or corresponding parts as in FIG. The difference from FIG. 1 is that the temperature of the brake coil 10 is measured by the temperature detector 23, the resistance value of the brake coil is estimated based on this temperature based on a predetermined formula indicated by reference numeral 24, and the voltage is determined according to the estimated resistance value. The command value 22 is set as a command value.

That is, the temperature of the brake coil 10 detected by the temperature detector 23 is T, and the temperature, the resistance value R ₂₀ Metropolitan brake coil 10 when the 20 ° C. measured in advance of the current on the basis of the following equation The resistance value Re is estimated.

  Then, the estimated resistance value Re is substituted for R in the above-described (Expression 1) to set the voltage command value 22. As a result, a more appropriate voltage command value 22 can be set without being affected by a change in resistance value due to a temperature change of the brake coil.

It is the schematic which shows the structure of Embodiment 1 of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram for explaining the operation of the first embodiment, where (a) shows a current detection value and a current command value, (b) shows a real current of a brake coil, and (c) shows a voltage command. It is a figure which shows a value. It is a block diagram which shows the principal part of Embodiment 2 of this invention. It is the schematic which shows the general structure of the brake control apparatus of the conventional elevator. It is explanatory drawing which shows operation | movement of the brake control apparatus of the conventional elevator.

Explanation of symbols

1 basket,
2 Sieve,
3 main rope,
4 counterweight,
5 winding motor,
6 Flakes drum,
7 Brake shoes,
8 fixed part,
9 Tension spring,
10 Brake coil,
11 Armature,
12 Brake contact,
13 switching elements,
14 PWM,
15 current detector,
16 A / D converter,
17 Current command value,
18 Current controller.

Claims (2)

  A spring device that constantly presses the brake shoe against the brake drum of the elevator to generate a braking force, and a brake that releases the braking force by pulling the brake shoe away from the brake drum against the spring device when biased In an elevator brake control device having a coil, a switching element for a step-down chopper for controlling the current of the brake coil by PWM, a current detector for detecting the current of the brake coil, and an output of the current detector as a digital signal An A / D converter that converts the output to the PWM, a current controller that outputs a voltage corresponding to a difference between an output of the A / D converter and a command current value to the PWM, and the current detector or the A / D converter. And a switching device for switching the voltage output to the PWM from the current detector to a command value of a predetermined voltage when an abnormality is detected. Brake control device for an elevator, characterized in that.   2. The temperature of the brake coil is detected, a resistance value of the brake coil is estimated from the temperature, and a command value of the predetermined voltage is set according to the resistance value. Elevator brake control device.

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