JPH0140598B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stopping a carrier of a linear induction motor (hereinafter referred to as LIM).

Because LIMs have a simple and robust structure, they are widely used as land transportation vehicles, for example, to transport documents and the like to predetermined locations.

In a transport system using LIM, a rail is provided for the transport object to travel on the transport path, and a station section is installed at one or more predetermined positions on the rail to accelerate or stop the transport object. is provided. At each station
A traveling magnetic field generating coil, which is the primary field coil of the LIM, is attached, and a secondary conductor made of a non-magnetic good conductor such as aluminum is attached to the carrier. When the magnetic field from the traveling magnetic field generation coil crosses the secondary conductor, eddy currents are generated in the secondary conductor, and the Lorentz force due to the interaction between this eddy current and the magnetic field causes the secondary conductor to be attached to it. It is known that a carrier can be accelerated or decelerated.

Conventionally, when stopping a conveyor at a desired position,
The conveyor was mechanically braked. However, the mechanical stopping method has problems in that the mechanical force applied to the carrier causes noise and wears out the wheels and rails. In order to avoid this problem, each station is equipped with an alternating current single-phase coil (hereinafter referred to as AC coil) or a direct current coil (hereinafter referred to as DC coil), which is electromagnetically opposite to the traveling direction of the secondary conductor. One possible method is to apply a force in the direction to stop it. However, AC
Stopping methods using coils, DC coils, or a combination thereof have a problem in that the maximum speed at which a carrier entering a desired stopping device can be stopped is relatively small.

In view of the above problems, the present invention provides a linear induction motor by appropriately controlling reverse excitation of a traveling magnetic field generating coil and excitation of an AC coil and a DC coil according to the position and speed of a conveyor. Reduces fatigue failure of the mechanism and reduces noise when the conveyor is stopped,
In addition, the maximum speed at which the conveyor can be stopped is increased, and braking of the conveyor is appropriately controlled depending on the high, medium, and low speeds of the conveyor to stop it at the desired stop position. The purpose is to ensure that

In order to achieve the above object of the present invention, the present invention provides a traveling magnetic field generating coil provided on the primary side, and a traveling magnetic field generating coil provided on the secondary side driven by the magnetic field generated by the traveling magnetic field generating coil. A secondary conductor is fixed to the conveyor body on which the object to be conveyed is mounted, and a force is provided on the primary side to electromagnetically apply a force to the secondary conductor in the opposite direction to the traveling direction to stop the conveyor body. DC coils and AC single-phase coils with different effective ranges and strengths, and multiple conveyance coils that are arranged at predetermined intervals along the conveyance direction of the conveyance object and continuously detect the passage of the conveyance object in the conveyance direction. a position detector for detecting the position of the carrier using a signal from the carrier detector; and a speed detector for detecting the speed of the carrier using the signal from the carrier detector. Linear induction equipped with
The motor detects the passing speed of the carrier at the position of the carrier detector when passage of the carrier is detected by any of the carrier detectors, and outputs an output from the carrier detector. detecting the position of the carrier based on the detection position, and when the detected position is a predetermined first position and the speed is greater than a predetermined speed, reverse excitation of the traveling magnetic field generating coil; applying a brake so that the conveying body is reduced to a predetermined speed, or when the speed is lower than the predetermined speed, the conveying body is conveyed without applying reverse excitation by the traveling magnetic field generating coil; The position detected based on the output from the detector is located at a predetermined second position corresponding to the effective range.
When the carrier is in the position, the carrier is controlled to be stopped by energizing the DC coil and/or the AC single-phase coil within the effective range of the force of the DC coil and the AC single-phase coil. A method of stopping a carrier using a linear induction motor is provided.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a perspective view schematically showing a part of a transport system using LIM. In FIG. 1, a traveling magnetic field generating coil group 2 is wound around a primary iron core 1. As shown in FIG. Three-phase alternating current is supplied to the coil group 2 to generate a traveling magnetic field. A rail 3 is laid on the iron core 1, and a carrier 5 with wheels 4 runs on this rail 3. A secondary conductor 6 is placed at the bottom of the carrier 5.
is fixed to the secondary conductor 6, and the carrier fixed to the secondary conductor travels due to the interaction between the magnetic field generated by the traveling magnetic field generating coil group 2 and the eddy current generated in the secondary conductor 6 by this magnetic field. In FIG. 1, for the sake of simplification of the drawing, the traveling magnetic field generating coil 2 is replaced by the iron core 1.
Although it is wound only on one side, it may be wound on both sides.

FIG. 2 is a block circuit diagram showing one embodiment of a device for realizing the conveyor stopping system according to the present invention. In FIG. (four in the figure) optical sensors S ₁ , S ₂ ,
S ₃ and S ₄ are provided. The carrier 5 running on the rail 3 is provided with slits 8 at regular intervals in the traveling direction, and when the carrier 3 passes the position where each optical sensor is arranged, each of the slits 8 is connected to the optical sensor. detected by. Detection signals from each of the optical sensors are supplied to a speed detector 10 and a position detector 12. In the speed detector 10, the speed of the conveyor is calculated from the number of slits detected per unit time, and in the position detector 12,
The position of the carrier is calculated from the position of the optical sensor and the number of detection slits. Although this position detection and speed detection itself is based on a well-known method, it will be explained in detail with reference to FIG. 5 for ease of understanding. In FIG. 5, the relationship between the sensor arrangement and the number and width of the slits of the carrier will be explained first. When the conveyor passes through sensors S ₁ to _{S 4} in the order of S ₁ → S ₂ → S ₃ → S ₄ , the slit tip crosses S ₁ .
Pulses begin to be output from S ₁ (Fig. 5a, when the rear end of the slit advances to a position opposite to S ₁ , the tip of the slit reaches a position where it crosses S ₂ , and pulses from S ₂ begin to output) (Figure 5b).

Since the above positional relationship is set in the same way from S ₂ to _{S 4} (Fig. 5 c, d), the pulse output from S ₁ to S ₄ when the carrier crosses the sensor is sequentially By switching, continuous pulse output can be obtained as shown in FIG. 5e.

Therefore, when the carrier passes between the sensors,
The sensor pulse outputs sent to the speed detector and position detector are sequentially switched to S ₁ to S ₄ .

The speed detector is the sensor _S1 which is continuously inputted above.
The number of pulses of the pulse output of S ₄ is S _i (i=1, 2, 3
Or 4) Start counting from the output, calculate the passing speed at S _i from the number of counts per unit time, and calculate the slit width when the position detector also starts counting from the output of pulse output S _i . Every time a count is made using , the position of the transport body that has progressed from the S _i position in the S ₄ direction is calculated.

The velocity and position thus obtained are, respectively,
The signal is input to a speed comparator 14 and a position comparator 16, and compared with a predetermined value. In the speed comparator, a signal indicating a high speed range H, a medium speed range M, or a low speed range L is applied to the gate circuit 18 by comparing a predetermined speed value and an input value. The position comparator 16 compares the input value with the value of a predetermined approach position near the desired stop position, and when the input value falls within the predetermined approach position, it gives a signal to the gate circuit 18 and controls the gate circuit 1.
Open 8. The gate circuit 18 is the position comparator 1
6, high speed range H, medium speed range M or low speed range L from speed comparator 14.
Switches 20-1, 20-
2 or 20-3, respectively, to drive the stop positioning section 22. The stop positioning section 22 is
It is provided in the station section, and has an AC coil and a DC coil in addition to the traveling magnetic field generating coil 2 (FIG. 1), and these coils are driven according to the approach speed of the carrier.

The switch 20-1, which turns on and off the traveling magnetic field generating coil of the LIM, is preferably an AC zero-cross switch in order to prevent malfunctions due to noise generated when the switch is opened and closed, but other switches may also be used. When using an AC zero-cross switch, the switch 20-1 may remain on for a while after the switch 20-1 is instructed to turn off from the gate circuit 18, and the traveling magnetic field generating coil may be reversely excited more than necessary. be. In order to prevent this phenomenon, the minimum speed in the high speed range H that generates brakes due to reverse excitation is set slightly higher.
The condition was set to be considered to be a medium speed range.

FIG. 3 is a flowchart for explaining a control method according to one embodiment of the conveyor stopping system according to the present invention, and FIG. 4 is a flow chart for explaining the position and speed of the conveyor moving according to the flowchart of FIG. It is a graph showing a relationship. In FIGS. 3 and 4, the method for controlling the stoppage of the carrier includes the following steps (1) to (4).

(1) First approach position P ₁ close to desired stopping position P ₃
It is detected that this point has been reached (step 31).

(2) Determine the speed v of the carrier (step 32), and if it is in the high speed range H, reverse excite the magnetic field generating coil and apply a strong brake to the carrier (step 32).
33), in the medium speed range M, the DC coil is turned on and when the secondary conductor passes through the DC magnetic field, the brake is applied using the force that acts in the direction that impedes the movement (step 35). If it is area L, the second approach position is closer than the first approach position _P1 .
Determine whether _P2 has been reached or not (step
37).

(3) If the first approach position is in the high speed range, the speed is determined before reaching the second approach position _P2 while applying reverse excitation (step 34), and if it is still in the high speed range, reverse excitation is applied. Continue to apply (step 33) (see _C1 in Figure 4), and when the medium speed range is reached, cut off the reverse excitation (step 34), and if the second approach position has been reached (Y at step 36), proceed to step 38. Then, braking is performed by excitation of the AC coil and DC coil, and if the second approach position has not been reached (N at step 38), the brake is applied by the DC coil (step 35) (see Fig. 4, _C2 ). If it is determined that the speed is in the medium speed range M when passing _P1 (step 35), the brake is applied by the DC coil (step 35) (see Figure 4, _C3 ). If it is determined that the vehicle is in the low speed range L when passing _P1 (step 32), the vehicle coasts without applying the brake until it reaches the second approach position _P2 . (See Figure 4 _C4 ) (4) When the second approach position _P2 is detected (step
36, 37), it falls within the effective range of the AC coil, so the AC
The brake is applied by the coil and the DC coil to stop the vehicle at the desired stopping position.

As point P ₁ where the LIM brake is applied to the conveyor,
If you start counting from the _S1 output, the _S1 point passing speed is calculated from the number of pulses per unit time, and by multiplying the count number by the width of the slit, _P1 is determined by the distance traveled from the _S1 position. Ru.

Similarly, braking with DC coil/AC single phase coil
As P ₂ , if you start counting from S ₂ output,
The _S2 point passing speed is calculated from the number of pulses per unit time, and _P2 is determined by the distance traveled from the _S2 position by multiplying the count number by the width of the slit.

As mentioned above, the advancing position of the conveyor depends on the number of pulses of the sensor output that starts counting.
Positions P ₁ , ₂ and ₃ are not mechanical position detection points.

The above conveyance body stop control can be realized either by hardware as shown in FIG. 2 or by software using a microcomputer or the like.

Since the braking force by the DC coil is relatively small, the carrier does not stop before it enters the second approach position, which is the effective area of the AC coil.

In addition, as mentioned above, while constantly comparing the position and speed with predetermined values, reverse excitation of the traveling magnetic field generation coil, AC
Since the drive of the coil and DC coil is controlled, it is possible to avoid applying the brakes too much and causing the vehicle to start in reverse before the stop position.

In the above-described embodiment, speed detection and position detection were carried out by using an optical sensor and by providing a slit in the carrier, but it is also possible to provide a secondary conductor slit fixed to the carrier, or by using an inductor or an inductor. This can also be done using a magnetic stripe or the like.

As is clear from the above explanation, the present invention provides a linear induction system using a mechanical brake.
Not only is fatigue failure of the motor mechanism prevented, but the maximum speed at the stop position of the conveyor is increased,
Furthermore, since an electromagnetic brake is appropriately applied to the conveyor according to the position and speed of the conveyor, it is possible to ensure that the conveyor is stopped at a desired stop position.

[Brief explanation of drawings]

FIG. 1 is a perspective view schematically showing a part of a conveyance system using a linear induction motor;
FIG. 2 is a block diagram showing an embodiment of a device for realizing the conveyor stopping method according to the present invention, and FIG. 3 is a flowchart for explaining a control method according to an embodiment of the conveyor stopping method according to the present invention. Chaat, 4th
This figure is a graph showing the relationship between the position and speed of the carrier moving according to the flowchart of FIG. 3, and FIG. 5 is a waveform diagram illustrating position detection and speed detection of the carrier. 1... Iron core, 2... Coil group for generating a traveling magnetic field, 3...
Rail, 4...Wheel, 5...Transporter, 6...Secondary conductor,
8...Slit, 10...Speed detector, 12...Position detector, 14...Speed comparator, 16...Position comparator, 1
8...Gate circuit, 20-1, 20-2, 20-3
...Switch, 22...Stop positioning section.

Claims (1)

[Claims] 1. A traveling magnetic field generating coil provided on the primary side and a secondary conductor provided on the secondary side and driven by the magnetic field generated by the traveling magnetic field generating coil are fixed and covered. A direct current that is provided on the primary side and has different effective ranges and strengths for stopping the conveyor by electromagnetically applying force to the secondary conductor in the opposite direction to the traveling direction. a coil and an AC single-phase coil; a plurality of carrier detectors that are arranged at predetermined intervals along the transport direction of the carrier and continuously detect passage of the carrier in the transport direction; and the carrier detector. a position detector for detecting the position of the carrier using a signal from the carrier; and a speed detector for detecting the speed of the carrier using the signal from the carrier detector. In the motor, detecting the passing speed of the carrier at the position of the carrier detector when passage of the carrier is detected by any of the carrier detectors (32, 34).
At the same time, the position of the carrier is detected based on the output from the carrier detector (31, 36, 37), and the carrier has passed a predetermined first position (Y in 31); And, when the speed is in the high speed range (H at 32, 34), the traveling magnetic field generating coil is reverse excited so that the conveying body is lowered from the speed in the high speed range to the speed in the medium speed range. (33), and when the conveyance object has passed the first position (Y at 31) and its speed is in the medium speed range (M at 32, 34), the conveyor Until the body reaches a predetermined second position corresponding to the effective range, the brake is applied only by the DC coil (35), and when the conveyor body has passed the first position (Y at 31). ), and when the speed is in a low speed range lower than the speed in the medium speed range (L at 32), the conveyor is coasted until it reaches the second position, and the conveyor moves from the second position to the second position. After the elapsed time (Y at 36 and 37), the conveyor is stopped by exciting the DC coil and the AC single-phase coil within the effective range of the force of the DC coil and the AC single-phase coil (38). 1. A method for stopping a conveyance object using a linear induction motor, characterized in that the conveyance object is controlled to be stopped by a linear induction motor.