JPH09284992A - Overload protector fro lifter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To get an overload protector which is sensitive in reaction to overload and is not affected by the ambient temperature, by operating a circuit breaker when an overcorrect is detected in a certain period of time after the power is turned on. SOLUTION: A sensor 7 detects the current of a motor for ascent and descent, and it input that into a comparison circuit 11 and a detection circuit 13. The comparison circuit 11 compares it with the reference value from a reference determining means 9, and when it get over the reference value, a voltage V6 is outputted. In the detection circuit 13, AND is taken with the voltage V3 of a transmission line, and when AND condition is materialized, the output V5 being delayed by the set time of a timer 14 is outputted from a timer circuit 15. Then, in the AND circuit 16, the AND of the voltages V5 and V6 is taken, and when AND condition is materialized, it is inputted into an abnormality output hold circuit 20, and a circuit breaker operates in response to the output. The output of the abnormality output hold circuit 20 is held until a reset switch 19 is pressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overload protection device for a lifting device used in a multi-story parking system, a multi-story warehouse or the like.

[0002]

2. Description of the Related Art As a conventional device for detecting an overload of a lifting device, a device mainly using an electronic principle using a piezoelectric element or the like capable of detecting an overload even at rest is mainly used. In addition, as a method of detecting after the lifting device starts moving, a method of using a current limiting circuit of an inverter used for speed control during lifting is known. There is also a method of using a meter relay as a simple detection device, and the simplest method is generally to use a thermal relay for protecting a motor.

[0003]

Since the inverter used in the above-mentioned conventional device is made as a speed control device, it has various functions, and overload detection also has a part of its original function. It is only used. Therefore, it is not efficient to use the inverter only for overload detection because there are too many unnecessary functions. Further, since the inverter has a larger main body than other control devices, there is a problem that the container to be stored also becomes large. The meter relay measures the current of the target circuit directly or via CT (current transformer), and the meter part has a pointer that can be set mechanically and the pointer of the meter body. When the pointer swings, the relay operates. Also, the size of the meter relay is smaller than that of the inverter, but there is a limit to installation because it has a meter part, and the thermal relay does not operate instantaneously unless a current of several times the reference value flows, There is a problem that it is easily affected by a difference in ambient temperature.

[0004]

In order to solve the above-mentioned problems, the present invention proposes a current sensor for detecting an input current of a lifting drive motor of a lifting device and a reference setting for setting a reference value for comparison. Circuit, a comparison circuit for comparing the output of the current sensor with the output of the reference setting circuit and outputting when the output of the current sensor is large, and an AND circuit for outputting when the output of the current sensor exceeds a certain level. A current detection circuit for detecting the start of the electric motor, a timer circuit for outputting the output of the current detection circuit with a set time delay, and an AND circuit for inputting the output of the timer circuit and the output of the comparison circuit, The output of this AND circuit is input to the OR circuit, and the output of this OR circuit is set to AN.
An abnormal output hold open circuit for self-holding with priority given to output by inputting the power supply voltage to the AND circuit through a reset switch and inputting the output of the AND circuit to the OR circuit. Then, the overload protection device for the lifting device is constructed so that the power supply switch of the electric motor is opened at the time of overload.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of an electric circuit of a lifting device to which the present invention is applied. In FIG. 1, reference numeral 1 is a lifting drive motor (induction motor) of the lifting device, and 2 is a power supply connected to the motor 1. A power transmission line 3, a circuit breaker which is a power source switch inserted in the power transmission line 2, a trip coil 4 for opening and closing the circuit breaker 3, and an electromagnetic switch 5 provided in the middle of the power transmission line 2, Reference numeral 5A is a switch that is closed when the electric motor 1 is rotated in the forward direction, 5B is a switch that is closed when the electric motor 1 is rotated in the reverse direction, and 6 is an overload protection device of the present invention connected to the power transmission line 2. is there. 2A is this overload protection device 6
The power transmission line that supplies power by connecting the power transmission line 2 to
B is a power transmission line for measurement.

FIG. 2 is a block diagram showing an example of the overload protection device 6. In the present embodiment, a current sensor 7 connected to a power transmission line 2 that detects an input current of a lifting drive motor 1 of a lifting device, and a variable resistor connected to the power transmission line 2 to set a reference value for comparison. a reference setting circuit 9 consisting of 8, the output v of the output v ₁ and output v ₂ and by comparing the current sensor 7 of the reference setting circuit 9 of the current sensor 7
_A comparator circuit 11 including a comparator 10 that outputs when ₁ is large, and an output v ₁ of the current sensor 7 and a power supply voltage v ₃ of the power transmission line 2 are input to an AND circuit 12 to input the electric motor 1
Timer circuit 15 including a current detection circuit 13 for detecting the start of the current and a timer 14 for outputting the output v ₄ of the current detection circuit 13 with a delay of a set time (for example, about 1 second).
And the output v ₅ of the timer circuit 15 and the comparison circuit 1
AND circuit 16 for inputting the output v _{6 of} 1 and this AN
The output v ₇ of the D circuit 16 is input to the OR circuit 17, the output v ₈ of the OR circuit 17 is input to the AND circuit 18, and the power supply voltage v ₉ of the power transmission line 2 is input to the AND circuit 18 via the reset switch 19. And an abnormal output hold circuit 20 for inputting the output v ₁₀ of the AND circuit 18 to the OR circuit 17 and outputting the abnormal output v ₁₀ from the abnormal output hold circuit 20 at the time of overload.
₁₁ is led to the above-mentioned trip coil 4 through the electric wire 21 shown in FIG. 1 so that the circuit breaker 3 which is the power source switch of the electric motor 1 is opened.

Next, the operation of the device of the present invention configured as described above will be described. When an elevating device such as a three-dimensional parking device or a three-dimensional warehouse equipped with the device of the present invention is being driven, if an overload is applied for some reason, the current of the elevating drive electric motor 1 increases. When this increased current flows through the current sensor 7 in FIG. 2, the corresponding output v ₁ is input to the comparison circuit 11 and the current detection circuit 13. Meanwhile, power transmission line 2
From the reference setting circuit 9 connected to the variable resistor 8
The reference voltage v ₂ set via is input to the comparison circuit 11. If the voltage v ₁ input to the comparator 10 is higher than the output voltage v ₂ from the reference setting circuit 9, the comparison circuit 1
The voltage v ₆ is output from 1.

The AND circuit 1 of the current detection circuit 13
Since the voltage v ₃ is input to the transmission line 2 from the power transmission line 2, the voltage v ₄ is output from the AND circuit 12 in combination with the input of the voltage v _{1 and} is input to the timer 14 of the timer circuit 15. By the action of 14, the voltage v ₅ is output with a delay (for example, about 1 second) set. The reason why the timer circuit 15 outputs the signal after a predetermined set time delay is that the current characteristic at the time of starting the lifting drive motor 1 is as shown in FIG.
This is because this unstable time is removed because it is not stable as shown in. FIG. 3 is a current characteristic diagram in which time is plotted on the abscissa and current is plotted on the ordinate, and Δt is an unstable section of the current (about 1 second or less).

The output v ₆ from the comparison circuit 11 described above,
When the output v ₅ from the timer circuit 15 is input to the AND circuit 16, the voltage v ₇ is output from this AND circuit 16 and is input to the OR circuit 17 of the abnormal output hold circuit 20.
Further, the AND circuit 18 in the abnormal output hold circuit 20
To the voltage v from the transmission line 2 via the reset switch 19.
₉ is input and the output voltage v ₈ of the OR circuit 17 is input, the voltage v ₁₀ from the AND circuit 18 output by the input of these voltages v ₈ and v ₉ is the OR circuit 17
Is entered. Therefore, once the abnormal voltage v ₇ is input to the abnormal output hold circuit 20, even if the voltage v ₇ is not input, the reset switch 1
Abnormal output v ₁₁ continues to be output unless 9 is opened. As described above, if the output from the overload protection device 6 of FIG. 1 flows to the trip coil 4 through the electric wire 21, the action of the trip coil 4 opens the circuit breaker 3 and Stop.

[0010]

As described above, according to the present invention, since an inverter, a meter relay, a thermal relay, etc. are not used unlike the prior art, the structure is simple and compact, and overload is prevented. Since the reaction is sensitive and is not adversely affected by the ambient temperature difference, it is possible to provide an inexpensive overload protection device for an elevator which can be installed anywhere.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a lifting drive motor of a lifting device having a device of the present invention.

FIG. 2 is a block diagram showing an electric circuit of the device of the present invention.

FIG. 3 is a current characteristic diagram at the time of starting the lifting drive motor.

[Explanation of symbols]

1 Motor for lifting drive 2 Transmission line 3 Circuit breaker (power switch) 4 Trip coil 5 Electromagnetic switch 5A Switch for forward rotation 5B Switch for reverse rotation 6 Overload protection device 7 Current sensor 8 Variable resistor 9 Standard setting Circuit 10 Comparator 11 Comparison circuit 12 AND circuit 13 Current detection circuit 14 Timer 15 Timer circuit 16 AND circuit 17 OR circuit 18 AND circuit 19 Reset switch 20 Abnormal output hold circuit v _{1 to} v ₁₁ Input / output voltage to each circuit 21 Wire

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H02H 3/08 H02H 3/08 D

Claims (1)

[Claims] 1. A current sensor for detecting an input current of a lifting drive motor of a lifting device, a reference setting circuit for setting a reference value for comparison, and an output of the current sensor and an output of the reference setting circuit are compared. And a current detection circuit for outputting the current sensor output when the output is large, and a current detection circuit for inputting to the AND circuit which outputs when the output of the current sensor is above a certain level to detect the start of the electric motor, and the current detection circuit. Of the output of the AND circuit and the AND circuit for inputting the output of the timer circuit and the output of the comparison circuit, the output of the AND circuit is input to the OR circuit, and The output is input to the AND circuit, the power supply voltage is input to the AND circuit via the reset switch, and the output of the AND circuit is input to the OR circuit. And an abnormal output hold circuit for self-holding output priority, so that the power supply switch of the electric motor is opened at the time of an overload.