JPH07177611A - Driver employing linear motor - Google Patents

Abstract

PURPOSE:To provide a driver performing continuous operation efficiently by decreasing the number at distributed linear motors. CONSTITUTION:Trucks are coupled endlessly on a loop track 1 so that they can be bend freely. Primary coils 21, 22, 23 of a linear motor are distributed along the track 1. Each truck is provided with the secondary conductor of linear motor and then the primary of linear motor is conducted to operate a carrier continuously at a constant speed. The total output of linear motor is set equal to the torque required for continuous constant speed running of a carrier. Furthermore, power supply voltage is increased at the time of starting or acceleration to enhance the output thus increasing the thrust.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor drive device in which the number of linear motors distributed in a loop-like start-up is reduced and efficient continuous operation is performed.

[0002]

2. Description of the Related Art An apparatus is widely used in which carts are flexibly and endlessly connected on a loop-shaped starter, and the carts are continuously operated to convey or sort the articles. As a drive system for this device, initially, a system was used in which a group of bogies are connected by a chain, a mechanical property is provided in a part of the device, and driving is performed via a driving electric motor, a speed reducer, a chain wheel, etc. With this, the layout of the device is limited to a planar configuration, and there are various problems such as noise from the drive device and connecting chain, maintenance of these components and measures against wear. The method to do was developed.

Since linear motors have a finite length structure on both the temporary side and the secondary side, their relative positions are separated from each other in a short time after energization, and thrust is no longer transmitted. Therefore, in general, an intermittent driving method is used. Is often considered. However, if the mechanism is such that the secondary conductors connected endlessly are continuously fed, the device can be continuously driven. Speaking of the transfer device, each carriage is provided with a reaction plate as the secondary side conductor of the linear motor, and the temporary side of the linear motor can be appropriately dispersed along the activation of the device to generate a driving force. .
Therefore, there is no need for a machine room, and there are many merits such as a reduction in the space occupied by the device, a reduction in noise due to the absence of a reducer and a chain, and a drastic reduction in maintenance costs. In addition, since each dolly can be connected by a universal joint method such as a ball joint, the layout of the entire apparatus can be three-dimensionally installed, and a new field is being opened in the transportation and sorting system.

The load torque of such a conveying device that continuously travels in a loop includes a starting torque, an acceleration torque, a low normal traveling torque, etc., and the values thereof are the type, size, quantity, and conveyance of articles to be conveyed. Speed, use and structure of other equipment,
Although it depends on various factors, a general tendency is that a large torque is required from startup to acceleration, and if steady running occurs, there is a slight fluctuation range for correcting speed fluctuations based on loading conditions. However, the load torque decreases to a nearly constant value.

Conventionally, the number of distributed linear motors is
Considering these torques, install the number of linear motors that can reliably generate the torque required for starting and accelerating, and after starting and accelerating in the rated power supply state, output so that only the necessary thrust is generated. It is being driven down.
As an example, in this case, it is widely practiced to employ an inverter so that the inverter can be operated efficiently at a low output.

The speed-thrust characteristic of a linear motor becomes a curve as shown in FIG. 4 when a rated voltage and a rated frequency are applied. That is, the thrust generated at the time of starting the linear motor has the largest value, and thereafter shows the drooping characteristic that decreases as the speed increases. The vo point is a motive speed vo (vo = vo = determined by the power supply frequency f and the pole pitch τ of the linear motor windings).
2fτ) is shown.

Further, a variable voltage and variable frequency type inverter is provided between the power source and the linear motor, and the speed-thrust characteristics when the voltage / frequency ratio is changed so as to be constant, the frequency is a parameter, and f1>f2>f3> f4
Then, it changes as shown in FIG. As shown in the time-speed characteristic shown in FIG.
When it is required to reach the rated speed v during the acceleration time t, when each truck is loaded with the rated load, the F1 value is required as the thrust for starting and acceleration during the time t, but the rated speed is After reaching v, stable operation is possible with the thrust of F2 value.

That is, in FIG. 7, when the inverter output frequency f1 is set, the thrust generated by the linear motor clears a required value F1, and the carrier device can perform a predetermined acceleration. However, if the power supply state remains unchanged after reaching the speed v, there is a speed up to the point A of the thrust F2 on the thrust characteristic curve of f1, and the speed rises to the speed value v1 over which the rated speed value is stretched. It will be. Therefore, the power supply frequency is changed from the speed v, and the thrust F2 is changed at the speed v.
In general, a method of driving by lowering to a frequency f2 having a speed characteristic such that the point B at which the noise occurs is on the thrust curve is performed.

[0009]

As described above, in many cases, the linear motor is started at the rated output and is operated at a low output during the steady operation. Moreover, the linear motor has a large exciting current as compared with the induction motor, and therefore the loss is lost. However, there is a drawback that the efficiency is low, the power consumption is large when viewed from the human power side even when the output is low during low-normal driving, and the efficiency during continuous operation is low. From these points, it is desired to reduce the number of distributed linear motors in order to improve the efficiency of the driving device.

It is an object of the present invention to provide a drive device that reduces the number of distributed linear motors and performs efficient continuous operation.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object, in which a bogie is bendably and endlessly connected on a loop-shaped track, and a linear motor is provided along the track. A temporary arrangement of coils is installed in a distributed manner, and each of the carriages has a linear motor secondary-side conductor, and a distributed arrangement is provided in a carrier device that energizes the temporary side of the linear motor to continuously perform constant-speed operation. The constant total output of the linear motor is set to a value equivalent to the required torque during continuous constant speed traveling of the transfer device, and the power supply voltage is increased to increase the output and increase thrust when the device is started and accelerated. That is the summary.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A drive device using a linear motor of the present invention will be described below with reference to the illustrated embodiments. In the figure, reference numeral 1 denotes a track of a traveling path which is arranged in a loop shape and is suitable for conveying articles. A truck connected to each other in an endless manner is arranged on the track 1 of the traveling path, and linear trucks are provided along the track. The motor primary side coils are arranged in a distributed manner, and the truck is driven via the linear motor secondary side conductor (reaction plate) provided on the truck. The linear motor primary side coils 21, 22, 23, ... Distributed along the track 1 are driven by the induction voltage regulator 3.

Further, on the track 1 serving as a conveyance path, there is provided a photoelectric encoder 5 which counts the passage of the truck and detects the speed by repeating light transmission and light shielding at intervals of the secondary conductor of the linear motor attached to each truck. The linear motor is controlled by providing the detection signal to the control motor 4 of the induction voltage regulator 3 to raise or lower the power supply voltage.

Next, the relationship between thrust and speed using a linear motor will be described with reference to FIG. Now, if the output of the linear motor for holding the thrust F1 is P1 and the output for holding the thrust F2 is P2, the relationship of P1> P2 is clearly established.

The control system is a voltage control system under a constant frequency, and the continuous rated output of the linear motor at the rated voltage is P2. In contrast to the required thrust F2 at low normal running, the required thrust F1 at startup / acceleration is

[0016]

[Formula 1]

It can occur when the voltage is raised up to. An encoder that detects the passing speed of the traveling vehicle is provided, and the setting is changed to the rated voltage at the end of acceleration, speed fluctuations are also detected, and the voltage is finely controlled in conjunction with the power setting device to maintain a steady speed. You can

Therefore, the operation of the apparatus having the above-mentioned structure will be described with reference to FIG. Now, when a start command is given to the device, the voltage rises to a preset voltage Emax, clears the thrust F2, and accelerates until the encoder command reaches a speed Vn close to V. The voltage gradually decreases from Vn, reaches V, reaches the rated voltage (or an approximate value of the rated voltage), and the steady operation is performed.

In the industrial transport system, the time required to complete the startup is set within 5 minutes at the longest, and a thrust of 200% and a voltage increase of 1.4 times are required for the linear motor. Is sufficiently durable, and the number of conventional linear motors used can be significantly reduced.

In this embodiment, since the carrier device has a large inertia, it is not necessary to have a perfect speed response and the input voltage can be easily boosted up to 200%. However, it is needless to say that the voltage changing means of the present invention uses Emax as the value of the power supply voltage, the linear motor has a low rated voltage, and a semiconductor type voltage regulator may be adopted.

[0021]

The drive device using the linear motor of the present invention is
On the looped track, bendable and endlessly connected bogies are connected, and linear motor temporary coils are distributed along the track.Each bogie is equipped with a linear motor secondary conductor. In a conveyor that has the above-mentioned configuration and energizes the linear motor on the temporary side for continuous constant-speed operation, the total constant output of the distributed linear motors is equivalent to the required torque for continuous constant-speed traveling of the conveyor. The value is set to increase the power by increasing the power supply voltage at the time of starting and accelerating the device to increase the thrust, so the number of distributed linear motor primary coils can be reduced, and the steady state can be reduced. There is an advantage that the linear motor can be driven in the most efficient state during traveling.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a drive device using a linear motor of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a voltage and a speed when the vehicle is traveling by a linear motor.

FIG. 3 is a graph showing a relationship with thrust velocity.

FIG. 4 is a diagram showing speed-thrust characteristics of a linear motor.

[Fig. 5] Speed when a variable frequency inverter is provided-
It is a figure which shows a thrust characteristic.

FIG. 6 is a diagram showing time-speed characteristics at the time of startup acceleration.

FIG. 7 is a diagram showing a speed-thrust characteristic by an inverter drive.

[Explanation of symbols]

 1 Trajectory 21, 22 ... Linear motor primary coil 3 Induction voltage regulator 4 Control motor 5 Encoder

Claims (1)

[Claims] 1. A loopless track on which bogies can be bent and connected endlessly, and linear motor temporary coils are distributed along the track, and each of the bogies has a linear motor. It has a configuration with a secondary conductor,
In a conveyor that continuously energizes the temporary side of the linear motor to perform constant speed operation, set the total constant output of the distributed linear motors to a value equivalent to the required torque during continuous constant speed traveling of the conveyor. A drive device using a linear motor, which is characterized by increasing a power supply voltage at the time of start-up and accelerating to enhance output to increase thrust.