JP2007070017A - Variable-speed hoisting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable-speed hoisting device capable of determining the degree of the load without changing the rotational speed of a hoisting motor even when the load is changed. <P>SOLUTION: The variable-speed hoisting device comprises a motor 1 to be subjected to the variable-speed control by an inverter, a rotation sensor 2 for outputting the rotation pulse corresponding to the rotational direction and the rotation of the motor, a reference pulse generation means 5 for generating the reference pulse corresponding to the target rotation of the motor, a deviation counter 6 for outputting the deviation between the reference pulse generated by the reference pulse generation means and the rotation pulse output by the rotation sensor, an operation control means 8 which increases/decreases the output frequency of the inverter according to the output deviation from the deviation counter, and controls the operation of the motor so as to eliminate the output deviation, and a load determination means for determining the degree of the load corresponding to the output frequency. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a variable speed hoisting device, and more particularly to a variable speed hoisting device that controls the winding and unwinding speeds of a motor by an inverter.

  A conventional variable speed hoisting device includes an inverter that can output a first reference frequency and a second reference frequency that is higher than the first reference frequency, and a winding whose rotation speed is controlled by the output of the inverter. An upper motor, detection means for detecting the rotation speed of the hoisting motor, and the rotation speed detected by the detection means when the hoisting motor is hoisted and rotated at the first reference frequency is preset. And a switching means for switching the output of the inverter to the second reference frequency when the reference speed is exceeded. (For example, refer to Patent Document 1).

  In the conventional variable speed hoisting apparatus, the first reference frequency and an inverter that can output a second reference frequency that is higher than the first reference frequency, and the rotation speed are controlled by the output of the inverter. A hoisting motor, detecting means for detecting the rotating speed of the hoisting motor, and when the hoisting motor is being wound down at the first reference frequency, the rotational speed detected by the detecting means is A switching means is provided for switching the output of the inverter to the second reference frequency when the load judgment reference speed is lower than a preset value. (For example, refer to Patent Document 2).

  The conventional variable speed hoisting device also has a rotation sensor for detecting the rotation direction and the rotation amount of the motor that moves the load, and the target rotation amount of the motor when the load is suspended by two hoisting machines. A reference pulse generating means for generating a corresponding reference pulse, a deviation counter for outputting a deviation between the number of pulses of the reference pulse generating means and the number of pulses generated by the rotation sensor, and the output frequency of the inverter is increased or decreased. An operation control unit that performs operation control so as to eliminate the deviation output from the deviation counter is employed. (For example, refer to Patent Document 3).

Japanese Patent Publication No. 7-17344 Japanese Patent Publication No. 7-17345 Japanese Patent No. 3147199

  In the conventional variable speed hoisting devices shown in Patent Documents 1 and 2, since the slippage of the hoisting motor when operating at a fixed reference frequency is detected, the heavier the load, There is a problem that the speed is low in the hoisting operation and the speed is high in the hoisting operation.

  In addition, in the conventional variable speed hoisting device shown in Patent Document 3, the output frequency of the inverter is increased or decreased. Therefore, the reference frequency as shown in Patent Documents 1 and 2 is fixed. There is a problem that the method of determining the degree of load cannot be applied.

  The present invention has been made to solve the above-described problems, and it is possible to maintain the target rotational speed regardless of the weight of the load by increasing / decreasing the output frequency of the inverter and to adjust the degree of the load. An object is to provide a hoisting device.

  The variable speed hoisting device according to the present invention corresponds to an electric motor that is controlled at a variable speed by an inverter, a rotation sensor that outputs a rotation pulse corresponding to the rotation direction and the rotation amount of the motor, and a target rotation amount of the motor. A reference pulse generating means for generating a reference pulse, a deviation counter for outputting a deviation between the reference pulse generated by the reference pulse generating means and the rotation pulse output from the rotation sensor, and an output deviation from the deviation counter Operation control means for controlling the operation of the electric motor so as to eliminate the output deviation and load determination means for determining the degree of load according to the output frequency are provided.

  Since the variable speed hoisting device according to the present invention is configured as described above, the degree of load can be determined without changing the rotational speed of the hoisting motor even if the load changes. When hoisting a load with only one machine, for example, when lifting a suspended load from a melting tank in zinc dip plating, it is possible to stabilize the lifting speed that affects the finish of the plating, and overload Has the effect that it can be judged and stopped safely.

  Further, according to the present invention, even if the load changes, it is possible to operate without changing the rotation speed of the hoisting motor, and in this state, the degree of the load can be determined. When the load is suspended by the upper machine, even if the load applied to both hoisting machines is different, the speed of each hoisting machine is the same, so the suspended load does not tilt and at the same time, Even if one of the hoisting machines is overloaded, the overloading of the hoisting machine can be detected and stopped safely.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of the variable speed hoisting apparatus according to the first embodiment. As shown in this figure, the variable speed hoisting device is a hoisting motor 1 that rotates a drum of the hoisting machine, and rotates in conjunction with the hoisting motor 1 in accordance with the rotation amount and direction of the hoisting motor 1. A rotation sensor 2 that generates a rotation pulse, an operation circuit 3 having push buttons for winding and lowering, and a hoisting motor 1 that receives a hoisting command and a lowering command from the operating circuit 3 at that frequency. Generated by a reference frequency calculation circuit 4 for calculating a reference frequency aimed at synchronous operation without slipping, a reference pulse generation circuit 5 for generating a reference pulse corresponding to a calculation result of the reference frequency calculation circuit 4, and a reference pulse generation circuit 5 The accumulated reference pulse is counted, and the rotation pulse generated by the rotation sensor 2 is input and accumulated in the direction to cancel the accumulation of the reference pulse, thereby accumulating the deviation between the reference pulse and the rotation pulse. If the deviation counter 6 that outputs the count and the reference pulse accumulated value exceeds the rotation pulse accumulated value and the deviation counter 6 outputs a plus value, the correction frequency is increased faster as the plus value is larger, and the rotation pulse accumulated value becomes the reference pulse accumulated. If the deviation counter 6 outputs a negative value by exceeding the value, the correction frequency calculation circuit 7 operates so as to decrease the correction frequency faster as the negative value is larger, and the correction frequency calculation circuit 7 is added to the reference frequency of the reference frequency calculation circuit 4. The execution frequency output circuit 8 calculates and outputs the frequency of the voltage applied to the hoisting motor 1 in consideration of the correction frequency from

Next, the operation of the first embodiment will be described.
When the winding push button of the operation circuit 3 is pressed, the reference frequency calculation circuit 4 calculates to gradually increase the reference frequency from the starting frequency to the rated reference frequency for operation at the rated speed.

  A specific example will be described. The hoisting motor 1 is a 4-pole motor, and the synchronous speed at 60 Hz is 30 revolutions / second. When the rotation sensor 2 outputs 100 pulses per rotation of the hoisting motor, the rotation pulse at a synchronous speed of 60 Hz is 3000 pulses / second. When the reference frequency is 60 Hz, the rated reference pulse of 3000 pulses / second, which is the same as the rotation pulse, is generated from the reference pulse generation circuit 5. When the starting frequency is 6 Hz, it is 300 pulses, which is 1/10 of the rated reference pulse, but gradually increases until it reaches 3000 pulses / second at the rated reference frequency of 60 Hz.

  When the reference frequency is gradually increased after starting the hoisting operation, the execution frequency is also increased, and the hoisting motor 1 is accelerated. However, since the slippage during acceleration of the hoisting motor 1 is large, the accumulated value of the reference pulse to the deviation counter 6 is The accumulated rotational pulse value that cancels this out is smaller, and therefore the deviation count of the deviation counter 6 is positive.

  If a positive deviation count remains when the output of the execution frequency output circuit 8 reaches the rated reference frequency, the correction frequency increases as a result of the increase in the output of the correction frequency calculation circuit 7. The execution frequency output circuit 8 inputs it and further increases the execution frequency from the rated reference frequency. Then, the hoisting motor 1 further accelerates and the number of rotation pulses less than 3000 pulses / second increases, and as a result of the output pulse of the rotation sensor 2 exceeding 3000 pulses / second, the deviation count of the positive deviation counter 6 starts to decrease. After that it turns negative.

  When the deviation count becomes negative, the correction frequency from the correction frequency calculation circuit 7 starts to decrease and the rotation speed of the hoisting motor 1 decreases. As a result, when the rotation pulse of the rotation sensor 2 decreases and falls below the rated reference pulse of 3000 pulses / second, the deviation count of the deviation counter 6 starts to increase and then turns to positive. When the deviation count becomes positive, the correction frequency starts to increase and the hoisting motor 1 is accelerated. As a result, when the rotation pulse of the rotation sensor 2 increases and exceeds the rated reference pulse of 3000 pulses / second, the deviation count starts to decrease.

  By repeating this operation, the hoisting motor 1 continues to rotate so as to always output a rotation pulse around 3000 pulses / second of the rated rotation pulse, and a constant stable correction frequency remains. As the lifting load increases, the slippage of the hoisting motor increases. To compensate for this, the correction frequency also increases as the load increases.

An intermediate value between the correction frequency for constant speed operation at 100% load and the correction frequency for constant speed operation at 125% load is set as the overload detection reference value, and this overload detection reference value is set to constant speed operation. If the stable correction frequency inside exceeds, it is judged as overload.
By doing so, a 100% load is not detected as an overload, and a 125% load can be reliably detected as an overload. When an overload is detected, an overload signal is output to the outside through a relay contact or the like, and the hoisting operation is stopped.

  According to the first embodiment, even if an overload occurs, overload detection can be performed while performing a stable constant speed operation with zero slippage of the hoisting motor. Even when it is used, the load is not inclined and the work can be performed safely. Further, since it is not necessary to separately install a mechanical or electric overload detector, a small and low-priced device can be obtained.

  Next, a description will be given of a low-speed driving operation at one-sixth of the rated speed, that is, a synchronous speed of 10 Hz. When the winding push button of the operation circuit 3 is pressed, the reference frequency calculation circuit 4 calculates to gradually increase the reference frequency from the starting frequency to the low speed reference frequency for operation at 1/6 of the rated speed.

  A specific example will be described. The hoisting motor 1 is a 4-pole motor, and the synchronous speed at 10 Hz is 5 rotations / second. When the rotation sensor 2 outputs 100 pulses per rotation of the hoisting motor, the rotation pulse at a synchronous speed of 10 Hz is 500 pulses / second. When the reference frequency is 10 Hz, the reference pulse generation circuit 5 generates a low-speed reference pulse of 500 pulses / second that is the same as the rotation pulse.

  When the starting frequency is 6 Hz, it is 300 pulses, which is one tenth of the rated reference pulse. However, when the acceleration from 0 Hz to 60 Hz is set to 1 second until it reaches 500 pulses / second at the low speed reference frequency of 10 Hz, it increases at about 67 msec. Go.

  When the reference frequency gradually increases after starting the hoisting operation, the execution frequency also increases, and the hoisting motor 1 is accelerated. However, since the slipping in the low frequency region of the hoisting motor 1 is large, the accumulated value of the reference pulse to the deviation counter 6 is larger. However, the accumulated rotation pulse value that cancels the rotation is smaller, and therefore the deviation count of the deviation counter 6 becomes positive.

  If a positive deviation count remains when the output of the execution frequency output circuit 8 reaches the low speed reference frequency, the correction frequency increases as a result of the increase in the output of the correction frequency calculation circuit 7. The execution frequency output circuit 8 inputs it and further increases the execution frequency from the low speed reference frequency. Then, after the hoist motor 1 further accelerates and the number of rotation pulses less than 500 pulses / second increases and the pulse of the rotation sensor 2 exceeds 500 pulses / second, the deviation count of the positive deviation counter 6 starts to decrease. Turns negative.

  When the deviation count becomes negative, the correction frequency from the correction frequency calculation circuit 7 starts to decrease and the rotation speed of the hoisting motor 1 decreases. As a result, when the rotation pulse of the rotation sensor 2 decreases and falls below 500 pulses / second of the low speed reference pulse, the deviation count of the deviation counter 6 starts to increase and then turns to positive. When the deviation count becomes positive, the correction frequency starts to increase and the hoisting motor 1 is accelerated. As a result, when the rotation pulse of the rotation sensor 2 increases and exceeds the low speed reference pulse of 500 pulses / second, the deviation count starts to decrease.

  By repeating this operation, the hoisting motor 1 continues to rotate so as to always output a rotation pulse of about 500 pulses / second of a low-speed rotation pulse, and a constant stable correction frequency remains. As the lifting load increases, the slippage of the hoisting motor increases. To compensate for this, the correction frequency also increases as the load increases.

An intermediate value between the correction frequency for low-speed operation at 100% load and the correction frequency for low-speed operation at 125% load is set as the overload detection reference value, and this overload detection reference value is used for stability during low-speed operation. If the corrected frequency exceeds the specified value, it is judged as an overload.
By doing so, a 100% load is not detected as an overload, and a 125% load can be reliably detected as an overload.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. Since the configuration and basic operation of the variable speed hoisting apparatus according to the second embodiment are the same as those of the first embodiment, illustration and description thereof are omitted.

  The feature of the second embodiment is that a correction frequency when a constant speed operation is performed with a 25% load is set as a light load detection reference value, and this light load detection reference value falls below a stable correction frequency during constant speed operation. In other words, it is determined that the load is light. If it is determined that the load is light, output a light load signal to the outside via a relay contact, etc., and switch to light load high speed operation exceeding the rated speed.

  According to the second embodiment, it is possible to detect a light load while performing a stable constant speed operation in a state where the winding of the hoisting motor is zero, so even when two hoisting machines are used in a co-suspended form, The load is not tilted and it can work safely. Further, since it is not necessary to separately install a mechanical or electrical light load detector, a small and low-priced device can be obtained. It is also possible to provide this light load detection function together with the overload detection function of the first embodiment.

  Further, in Embodiments 1 and 2, the explanation was given at the time of hoisting operation. However, at the time of hoisting operation, the direction of rotation of the hoisting motor is reversed, and the rotational speed is reversed faster due to sliding. The determination is made when the output frequency is lower than the set value. The light load is determined when the output frequency is higher than the set value.

The variable speed hoisting device according to the present invention does not change the speed even if the load changes, and has a light load high speed function and an overload prevention function. This is ideal for applications where work speed is required and safety is required.
In particular, when two hoisting machines are suspended together, not only does it not tilt, but it can also be stopped safely even if one hoisting machine is overloaded and one of the hoisting machines is overloaded. 2 units by switching to light load high speed operation on condition that the light load judgment signal is also input from the partner machine when the own machine judges light load. At the same time, it is possible to switch to light-load high-speed operation, and light-load high-speed operation can be used even when suspended.

It is a block diagram which shows the structure of the variable speed hoisting apparatus by Embodiment 1 and 2 of this invention.

Explanation of symbols

1 winding motor, 2 rotation sensor, 3 operation circuit, 4 reference frequency calculation circuit,
5 Reference pulse generation circuit 6 Deviation counter 7 Correction frequency calculation circuit
8 Execution frequency output circuit.

Claims (8)

  An electric motor that is controlled at a variable speed by an inverter, a rotation sensor that outputs a rotation pulse corresponding to the rotation direction and the rotation amount of the motor, and a reference pulse generator that generates a reference pulse corresponding to a target rotation amount of the motor; A deviation counter that outputs a deviation between the reference pulse generated by the reference pulse generating means and the rotation pulse output from the rotation sensor; and the output frequency of the inverter is increased or decreased in accordance with the output deviation from the deviation counter. A variable speed hoisting device comprising: an operation control unit that controls the operation of the electric motor so as to eliminate a deviation; and a load determination unit that determines a degree of load according to the output frequency.   2. The variable speed hoisting device according to claim 1, wherein it is determined that the load is light when the output frequency is lower than a set value during the winding operation.   2. The variable speed hoisting device according to claim 1, wherein it is determined that the load is light when the output frequency is higher than a set value during the lowering operation.   4. The variable speed hoisting device according to claim 2, wherein when it is determined that the load is light, the target rotation amount of the electric motor is increased to switch to operation at a speed faster than the rated speed.   2. The variable speed hoisting device according to claim 1, wherein when the output frequency is higher than a set value during the winding operation, it is determined that the load is overloaded.   2. The variable speed hoisting device according to claim 1, wherein an overload is determined when the output frequency is lower than a set value during the lowering operation.   7. The variable speed hoisting device according to claim 5, wherein an overload signal is output when it is determined that the load is overloaded.   The variable speed hoisting device according to claim 5 or 6, wherein the operation is stopped when it is determined that the load is overloaded.

Images