JP2000053385A - Inverter type hoist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly switch a low speed operation and a high speed operation. SOLUTION: In a memory 14, a load ratio D, a voltage value V of power supplied to an inverter circuit 11, a current value I of power supplied to a motor 3 and a relation with an operating frequency (f) are stored. A controller 12 estimates the load ratio D applied to a hook block by a voltage value V of power supplied to the inverter circuit 11 detected by a voltage detecting device 17 and a current value I of power supplied to a motor 3 detected by a current detecting device 18, a designated operating frequency and the relation stored in the memory 14. The size of a preliminarily fixed speed change threshold value Dtha on the load ratio D and the estimated load ratio D are compared. According to this comparison result, one of a high speed operating frequency and a low speed operating frequency is outputted to the inverter circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter type hoist provided with an inverter circuit and capable of changing an operation speed.

[0002]

2. Description of the Related Art In general, an inverter type hoist performs a switching operation between a low speed operation and a high speed operation in accordance with a load applied to a hook block.

Conventionally, the operating speed is changed by previously setting a threshold value with respect to the slip amount of the motor having a fixed relationship with the load applied to the hook block or the output current from the inverter circuit to the motor. The determination is made based on whether the detected slip amount or the detected current is larger than the threshold value.

[0004]

However, in the prior art, under one condition (for example, a power supply voltage: 200 V, an operation frequency: 60 Hz, a load factor (= actual load / rated load × 1)
00 [%]): Only at 25%), a slip threshold or a current threshold, which is established as an appropriate threshold, is adopted. Therefore, when the power supply voltage, the operating frequency, or the load factor changes, an appropriate threshold is applied. The value may not be the value, and as a result, high-speed operation may be performed in spite of the state where low-speed operation is to be performed, and the hoist may trip due to overload.

That is, in the prior art, since the operating speed is changed by setting the value affected by other various parameters as a threshold value, the operating speed cannot be changed appropriately. Has a problem that the hoist may trip.

An object of the present invention is to provide an inverter type hoist capable of appropriately changing the operation speed and avoiding a trip of the hoist due to an overload by focusing on such a conventional problem. And

[0007]

In order to achieve the above object, an inverter type hoist comprises a load factor of a load applied to a hook block, a voltage value of power supplied to an inverter circuit, and a power value of power supplied to a motor. The relationship between the current value and the operating frequency is determined for each load factor, for each voltage, for each current,
Storage means for storing for each of various operating frequencies; detecting means for detecting a voltage value of the power supplied to the inverter circuit and a current value of the power supplied to the motor; The load value estimating means for estimating the load factor of the load applied to the hook block, based on the voltage value and the current value, the specified operating frequency, and the relation stored in the storage means. A predetermined speed change threshold is compared with the load factor estimated by the load factor estimating means, and one of a high-speed operation frequency and a low-speed operation frequency is selected according to the comparison result. And control means for outputting the selected operating frequency to the inverter circuit.

Here, the inverter type hoist includes threshold changing means for changing the speed changing threshold, and the control means changes the speed changing threshold by the threshold changing means. Then, the high-speed operation frequency may be changed according to the degree of the change.

Further, the control means of each of the above-mentioned inverter-type hoists previously stores an overload prevention threshold value larger than the speed change threshold value. Preferably, when the load factor estimated by the load estimating means is large, a motor stop command is output to the inverter circuit.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the inverter type hoist according to the present invention will be described below with reference to the drawings.

As shown in FIG. 2, the inverter type hoist according to the present embodiment rotates a drum 5 around which a hook block 1 for suspending a load, a wire 2 for suspending the hook block 1 are wound. Motor 3
A brake box 4 for stopping the rotation of the drum 5, a control box 10 having an inverter circuit for changing the rotation speed of the motor 3 and the like, and an operation panel 20 for giving an operator's instruction to the control box 10. ing.

As shown in FIG. 1, the operation panel 20
Hoist button 2 for instructing lifting of hook block 1
1, a lowering button 21 for instructing a lowering of the hook block 1, a threshold change volume 23 for instructing a change of a speed change threshold described later, and the like are provided.

In the control box 10, in addition to the inverter circuit 11 described above, a controller (load factor estimating means, control means) 12 for controlling the inverter circuit 11 in response to an operation signal or the like from an operation panel 20, and a power supply 9 And a current detector (detection means) 18 for detecting the current value of the electric power supplied to the motor 3 from the inverter circuit 11. The controller 12 transmits and receives signals between the frequency change volume 16 for changing the setting of the normal operation frequency and the operation panel 20, the inverter circuit 11, the frequency change volume 16, the voltage detector 17, and the current detector 18. Circuit 15, a memory 14 storing various operation programs, various data, and the like, and a CP for executing the operation program stored in the memory 14.
U13. In this embodiment, the frequency change volume 16 is provided in the controller 12,
This may be provided on the operation panel 20. In this embodiment, the threshold value changing volume 23 is connected to the operation panel 2.
However, this may be provided in the controller 12.

The memory 14 in the controller 12 has a V-D relationship between the voltage value V of the power supply 9 and the load factor D of the load applied to the hook block 1, and supplies the load factor D, the operating frequency f, and the motor 3 to the motor 3. -D with the current values Iu and Id
The fI relation is stored.

As shown in FIG. 3, with respect to the VD, various load factors D11 to V11n for various power supply voltages V11 to V1n.
~ Dmn are related. In this embodiment, since a commercial power supply of 200V ± 10% is used as the power supply 9, various power supply voltages V11 to V1n in the VD relation are:
A value in the range of 200 V ± 10% is defined. Also,
Various load factors D11 to Dmn in the VD relationship are 0 to 15
It is determined in the range of 0%.

As shown in FIG. 4, the DfI relationship is associated with each of the various load factors D11 to Dmn.
Various operating frequencies f1 to fs for each of the various load factors D11 to Dmn
Is associated with the hoist motor current value Iusmn and the hoist motor current value Idsmn. In this embodiment, D-
The various operating frequencies f1 to fs in the fI relation are determined in a range of 6 to 60 Hz that can be set by the frequency setting volume 21. The operating frequency range may be determined in a wider range depending on the specifications.

That is, the memory (storage means) 14
VDf-Iu and Id are related to various power supply voltages V11 to V11.
1n, various load factors D11 to Dmn, various operating frequencies f1
fs, various motor current values Iusmn, motor current values Idsmn
It is stored every time.

[0018] The memory 14 in the controller 12, further, the relationship between the speed change threshold Dtha and high-speed operation frequency f _H is stored. This will be described later in detail.

Next, the operation of the hoist according to the present embodiment will be described with reference to the flowchart shown in FIG.

First, the controller 12 determines whether a hoisting command, a hoisting command, or a stop command has been input as an operation signal (step 1). Among these commands, the hoisting command and the hoisting command are input to the controller 12 when the operator presses the hoisting button 21 and the hoisting button 22 of the operation panel 20. The stop command is input to the controller 12 when the operator releases the hoist button 21 or the hoist button 22 on the operation panel 20.

When a stop command is input, a stop command is output to the inverter circuit 11 to stop the power supply to the motor 3 and to drive the brake 4 to drive the drum 5
Is stopped (step 10). When a hoisting command or a hoisting command is input, the voltage value V of the power supply 9 is fetched from the voltage detector 17 (step 2).

When the power supply voltage value V is fetched, the operating frequency f (60 Hz in this embodiment) preset by the frequency change volume 23 is output to the inverter circuit 11 as an initial operating frequency (step 3). . As a result, the motor 3 starts rotating at a rotation speed corresponding to the initial operation frequency. When the motor 3 starts to rotate and the rotation speed is stabilized, the current value I of the power supplied from the inverter circuit 11 to the motor 3 is taken in from the current detector 18 (step 4).

When the current value I is fetched, the detected power supply voltage V, the detected motor currents Iu and Id, and the frequency change volume 23 are determined by using the VDF-Iu and Id relations stored in the memory 14. A load factor D corresponding to a preset operating frequency f is obtained, and this is set as the load factor D of the load currently applied to the hook block 1 (step 5).

When the load factor D of the load currently applied to the hook block 1 is obtained, the threshold volume 23
Speed change threshold value Dth related to the load factor set in advance
The magnitude relationship between a (in this embodiment, 25%) and the obtained load factor D is compared (step 6). If the determined load factor D is smaller than the speed change threshold value Dtha, in other words, if it is determined that the load currently applied to the hook block 1 is relatively light, the predetermined high-speed operation frequency is determined. f _H (in this embodiment, the 120 Hz.) to output to the inverter circuit 11 (step 8). When high-speed operation frequency f _H is outputted to the inverter circuit 11, the motor 3 begins to rotate at high speed, with a relatively light load is fast, which is hung on the hook block 1 is lowered hoisting or winding.

If it is determined in step 6 that the obtained load factor D is equal to or greater than the speed change threshold value Dtha, the calculated load factor D is further compared with a predetermined overload prevention threshold value Dthb. The magnitude relation is compared (step 7). If the obtained load factor D is smaller than a predetermined overload prevention threshold value Dthb,
If it is determined that the load currently applied to the hook block 1 is not very heavy but relatively heavy, the low-speed operation frequency f _L (in this embodiment, 60H
z. ) Is output to the inverter circuit 11 (step 9). When the low-speed operation frequency _L is output to the inverter circuit 11, the motor 3 starts rotating at a low speed, and the relatively heavy load applied to the hook block 1 is hoisted or lowered at a low speed.

If it is determined in step 7 that the obtained load factor D is equal to or larger than the predetermined overload prevention threshold value Dthb, the load currently applied to the hook block 1 is extremely heavy. If it is determined that the above condition is satisfied, a stop command is output to the inverter circuit 11 to stop the motor 3 (step 10).

Before starting the operation, the threshold value changing volume 2
When the speed change threshold value Dtha is changed by operating No. 3, basically the same processing as the above processing is executed. However, the speed change threshold Dtha is changed, based on the relationship between the speed change threshold Dtha and high-speed operation frequency f _H that is stored in the memory 14 within the controller 12, is output in step 8 high-speed operation frequency f _H is changed. This is because the load factor D capable of hoisting or lowering at a certain operating frequency f is inversely proportional to the square of the operating frequency f. For this reason, as shown in FIG. 5, the speed change threshold value Dtha related to the load factor D also changes the high-speed operation frequency f _H so as to be inversely proportional to the square of the high-speed operation frequency f _H. Specifically, for example, the speed change threshold Dtha is set to 2
If set to 5%, high-speed operation frequency f _H is 120
Hz, and when the speed change threshold Dtha is set to 50%, the high-speed operation frequency f _H becomes 84 Hz.

As described above, in the present embodiment, the relationship between the load D currently applied to the hook block 1 and each of the parameters V, f, Iu and Id which affect the estimation of the load is stored in advance. In addition, V,
Since f, Iu, and Id are applied to the above relationship, the load factor can be accurately estimated. Once this load factor is determined, it remains the same until the load is reapplied.
And the output currents Iu and Id do not change, so that if a threshold value is set for this load factor, switching between high-speed operation and low-speed operation is performed without being affected by fluctuation factors. be able to. As a result, the operating speed can be changed appropriately, and a hoist trip due to overload can be avoided.

[0029]

According to the present invention, since the load factor is accurately estimated and the speed change threshold is determined for the load factor which does not change until the load is re-applied, the influence of the fluctuation factor is determined. Thus, it is possible to perform an appropriate speed change without receiving such a change, and it is possible to avoid a hoist trip caused by an inappropriate speed change.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of an inverter type hoist according to an embodiment of the present invention.

FIG. 2 is a front view of the inverter type hoist according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between various power supply voltages and a load factor of the inverter type hoist according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a relationship between a load factor, various operating frequencies, and an output current of the inverter type hoist according to one embodiment of the present invention.

FIG. 5 is a graph showing a relationship between a speed change threshold value and a high-speed operation frequency of the inverter type hoist according to the embodiment of the present invention.

FIG. 6 is a flowchart showing an operation sequence of the inverter type hoist according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hook block, 2 ... Wire, 3 ... Motor, 4 ... Brake, 5 ... Drum, 9 ... Power supply, 10 ... Control box,
11 ... Inverter circuit, 12 ... Controller, 13 ... C
PU, 14 ... memory, 15 ... interface circuit, 1
6 ... frequency change volume, 17 ... voltage detector, 18 ...
Current detector, 20: operation panel, 23: threshold change volume.

Claims (3)

[Claims] 1. A hook block for suspending a load, a drum around which a wire for suspending the hook block is wound, a motor for rotating the drum, and an inverter for changing the rotation speed of the motor in accordance with a designated operating frequency. And a load factor of a load applied to the hook block, a voltage value of power supplied to the inverter circuit, a current value of power supplied to the motor, and the operating frequency. Storage means for storing the relationship for each of various load factors, for each of various voltages, for each of various currents, and for each of various operation frequencies, a voltage value of the power supplied to the inverter circuit, and a power supplied to the motor Detection means for detecting the current value of the voltage, the voltage value and the current value detected by the detection means, the specified operating frequency, and stored in the storage means A load factor estimating means for estimating a load factor of a load applied to the hook block, a speed change threshold value predetermined for the load factor, and the load factor estimating means. Control means for comparing the load factor and selecting one of a high-speed operation frequency and a low-speed operation frequency in accordance with a result of the comparison, and outputting the selected operation frequency to the inverter circuit. Inverter-type hoist characterized in that: 2. The inverter-type hoist according to claim 1, further comprising a threshold changing unit that changes the speed changing threshold, wherein the control unit controls the speed changing threshold by the threshold changing unit. When the value is changed, the high-speed operation frequency is changed according to the degree of the change. 3. The inverter type hoist according to claim 1, wherein the control means stores an overload prevention threshold value larger than the speed change threshold value in advance. An inverter-type hoist that outputs a motor stop command to the inverter circuit when the load factor estimated by the load estimating means is larger than the overload prevention threshold value.