JPH01278278A - Starting system for belt conveyor using wound-rotor type induction motor - Google Patents

Abstract

PURPOSE:To always start a belt conveyor for a predetermined period of time by sequentially short-circuiting the secondary resistors of motors of driving pulleys when the speed detection pulse value of a rotation detecting pulse generator attached to rotary pulley is smaller than the output of a linear command accelerator. CONSTITUTION:Motors 5, 6 are provided at a first drive pulley 2, and a motor 7 is provided at a second drive pulley 3 to form a multi-drive belt conveyor. Pulse generators 8, 9, 10 are respectively attached to the motors 6, 7 and a driven pulley 4. A speed calculator 12 integrates the number of pulses of the generator 10 to calculate an accelerating speed. On the other hand, a linear command accelerator 11 outputs a linearly increasing acceleration command value with the designated starting time as a target value. A comparator 13 sequentially reduces the secondary starting resistors of the motors 4-7 when the accelerating speed is smaller than a linear acceleration command value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for starting a belt conveyor for conveying various raw materials, earth and sand, and the like.

[Conventional technology]

When operating a belt conveyor or the like using a squirrel cage induction motor, full voltage starting is generally performed. However,
There was a problem in that the starting time was short, especially when the number of objects conveyed on the belt was small and there was no load, and the rapid starting generated large noise. Using a continuously variable transmission such as an eddy current coupling would solve this problem, but since it requires a large installation space, it may not be possible to use it due to the installation location.

As a way to solve such problems, the applicant of this application,
I first proposed the following starting method (Tokukō Kokō 1986-18).
(See Publication No. 38). In other words, in a wound induction motor that starts by sequentially reducing the secondary resistance, after the power is turned on, the secondary resistance is reduced by a timer until the motor starts rotating. After the motor speed starts to decrease, the secondary resistance is sequentially decreased when the detection signal corresponding to the motor speed becomes lower than the command value of the linear command device.

This allows for smooth acceleration, but since the secondary resistance is short-circuited by a timer until the motor starts rotating, the total starting time varies depending on changes in load conditions. It could not be applied for practical purposes.

[Problem to be solved by the invention]

Belt conveyors generally undergo large changes in load conditions.

Even at startup, there are cases where the engine is fully loaded, and there are cases where there is no load. Belt conveyors are designed to reduce secondary resistance so that a predetermined starting time is achieved when the belt is fully loaded, and the starting time is generally short when the load is light or no load.

By the way, mainly in the case of large-capacity drive belt conveyors, there is a multiple drive system in which the belt conveyor is driven by a plurality of electric motors depending on the capacity of the equipment, economical efficiency, etc.

In such a belt conveyor having multiple drive machines, if the method proposed in the above-mentioned Japanese Patent Publication No. 1838-1983 is used, each drive machine will be controlled to start at the same time, etc. but you need to do
The multiple drive system often starts with a time difference in order to establish the drive tension of the belt.

In addition, in the conventional multi-drive system, each drive is started simultaneously or at different times, and the secondary resistance of each drive wound induction motor is determined by focusing only on the starting characteristics of its own motor, and by starting the belt conveyor. It was starting up. As a result, in the case of staggered starting, an unbalanced torque was applied to the belt conveyor especially during starting, and the starting time of the belt conveyor varied depending on the load condition.

Particularly when there is no load, the belt conveyor starts when one drive is started, and the start is completed in a short time, so there is a problem that the mechanical shock that is applied to the machine and the belt is large, and the noise is also large. .

The present invention has been made in view of these conventional problems, and is capable of producing a belt conveyor without being affected by load fluctuations, regardless of single drive or multiple drive, and without imparting unbalanced torque to the belt conveyor during acceleration. The purpose is to start a belt conveyor without shock so that the acceleration time is always constant.

[Means to solve the problem]

In order to achieve this objective, a starting method for a belt conveyor using a wound induction motor according to the present invention uses a wound induction motor as a drive machine for the driving pulley in a belt conveyor having a plurality of driving pulleys and a plurality of driven pulleys. A pulse generator for rotation detection is attached to either one of the drive machines that drive each drive pulley and one of the driven pulleys to create a rise curve that can be set arbitrarily regardless of load fluctuations. A linear command accelerator is provided in which the linear command accelerator is set, and the linear command accelerator is linearly accelerated from a state where the primary side contactor of the motor is turned on to a starting time set in the linear command accelerator to the target time as a target value. The speed value of each drive machine is compared with the speed detection pulse value of a rotation detection pulse generator attached to the driven pulley, and when the pulse value of the pulse generator is smaller than the value of the linear command accelerator, The belt conveyor is characterized in that the belt conveyor is always started at a constant time by sequentially short-circuiting the secondary resistances to reduce the secondary resistances.

〔Example〕

Hereinafter, the present invention will be specifically described based on embodiments shown in the drawings.

Figure 1 shows the configuration of a belt conveyor starting control system.

The system shown in FIG. 1 has two drive units for driving the belt conveyor 1. The system shown in FIG. First drive pulley 2
The second drive pulley 3 has two electric motors 5 and 6, and the second drive pulley 3 has one electric motor 7, forming a multi-drive belt conveyor. A wound induction motor is used for each motor. Further, one electric motor 6 of the first drive section, the electric motor 7 of the second drive section, and the driven pulley 4 are each equipped with pulse generators 8, 9, and 10 for detecting the speed of the drive machine or the belt conveyor. Each pulse generator is used in the speed calculator 12 for belt slip detection.

The speed calculator 12 also integrates the number of pulses from the pulse generator 10 attached to the driven pulley 4.

Then, the acceleration speed is calculated from the change I in the number of pulses per unit time. On the other hand, at the same time that the primary side contactors 5B, 6B, and 7B of the electric motors 5 and 6°7 are turned on, the linear command accelerator 11 sets the set starting time to the target value,
Accelerate linearly until the target time. The comparator 13 compares the data of the linear command accelerator 11 designed and set in advance with the integrated value, and when the number of pulses of the pulse generator 10 is smaller than the speed value of the linear command accelerator 11, each electric motor Control is performed to sequentially control the secondary starting resistors 5 to 7, 5A to 7A. That is, the secondary starting resistance controller 14 performs an acceleration step to the next notch when the acceleration speed becomes a value less than or equal to that of the linear command accelerator 11 at each short-circuited notch of the secondary resistors 5A, 6A, and 7A. We will proceed with this. As a result, acceleration is always performed at a constant time without being affected by the load condition.

FIG. 2 shows an example of a speed-torque characteristic diagram of each electric motor using the multiple drive system. In the figure, the characteristics marked with ■ are the torque when motor 7 starts independently, the characteristics marked with ■ are the torque when started with two motors 7 and 6, and the characteristics marked with ■ are the torque when started with three motors 5 to 7. shows the torque.

FIG. 3 is an example of a time-speed characteristic diagram, and it can be seen that the actual acceleration speed follows the acceleration speed at the designed and set starting time.

In addition, by setting the secondary starting resistance as a resistance value in a binary system, and shorting the contactor that shorts this resistance in a binary system, many starting notches can be obtained with a small number of contactors, resulting in smooth starting performance. further improves.

Furthermore, a runaway and stall check is performed during acceleration to protect the belt conveyor from sudden changes in speed, ie, sudden changes in torque.

〔Effect of the invention〕

As explained above, in the present invention, the start timing of the linear command accelerator is not started by detecting the rotation of the pulley of the belt conveyor, but from the rotation command of the belt conveyor, that is, from the state where the primary side contactor of the electric motor is turned on. We have adopted a method of doing so. When driving a belt conveyor with multiple electric motors, the belt conveyor may start even with one electric motor depending on the load condition. Therefore, if you start the linear command accelerator at the same time as the operation command, the design and settings will depend on the load condition. Power is applied to the belt conveyor at a uniform acceleration torque rate corresponding to the acceleration time, and the belt conveyor is started at a fixed time.

Since the belt conveyor is smoothly accelerated in this manner, it is possible to start the belt conveyor without applying a shock to the drive mechanism of the belt conveyor.

This makes it possible to suppress the generation of noise and extend the life of the belt.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a configuration example of a device for carrying out the starting method of the present invention, Fig. 2 is a torque-speed curve according to the present invention, and Fig. 3 is a command curve by a linear command accelerator and an actual speed-time curve. It is. 1: Belt conveyor 2. 3:lKml+7'
-IJ4; Driven pulley 5~7: Electric motor 5A~
7A: Secondary starting resistor 5B to 7B: Primary side contactor 8 to 10: Pulse generator 11': Linear command accelerator 1
2: Speed calculator 13: Comparator 14: Secondary starting resistance controller Patent applicant Yasuyo Electric Manufacturing Co., Ltd. Representative
Masu Kobori (and 2 others) Figure 1 Figure 2 - 1◆j Shudo

Claims (1)

[Claims] 1. In a belt conveyor having a plurality of drive pulleys and driven pulleys, a wound induction motor is used as a drive machine for the drive pulley, and any one of the drive machines that drives each drive pulley and any one of the driven pulleys are used. A pulse generator for rotation detection is attached to each stand, and a linear command accelerator is installed with a rising curve that can be arbitrarily changed regardless of load fluctuations. The starting time set in the linear command accelerator is set as a target value, and linear acceleration is performed until the target time, and the speed value of the linear command accelerator and the speed detection pulse value of the pulse generator for rotation detection attached to the driven pulley are calculated. When the pulse value of the pulse generator is smaller than the value of the linear command accelerator, the secondary resistance of each drive machine is short-circuited in order to reduce the secondary resistance, so that the belt is always A belt conveyor starting method that uses a wound induction motor to start the conveyor.