JPS648556B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the traveling speed of a conveying body which is a driven part of a linear induction motor (hereinafter referred to as LIM or simply motor).

Because the LIM has a simple and strong structure, it is widely used as a land transportation vehicle, for example, to transport documents and the like to a predetermined location.

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 (hereinafter referred to as the primary coil), which is the primary field coil of the LIM, is installed, and a secondary conductor made of a non-magnetic good conductor such as aluminum is installed on the carrier. ing.
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.

Since the conveying body, which is the driven part, is made of a lightweight material, it may receive an excessive impact when it is accelerated or decelerated by the excitation of the primary coil. In particular, when there is only a small number of objects loaded on the conveyor, it is more susceptible to excessive impact, which can result in disarray of the loaded objects, noise caused by the conveyor bouncing on the rails, and fatigue of the mechanism. There is a problem that it may cause destruction. Furthermore, when multiple conveyors are run on a single rail, the same primary coil may not be excited with the same electric power due to differences in the weight of each conveyor carrying various loads and the coefficient of friction with the rail. Also, the traveling speed may differ depending on each carrier,
For example, if the traveling speed of the preceding conveying body is slower than the speed of the following conveying body, there is a problem that the conveying bodies collide with each other.

Conventionally, in order to deal with the above-mentioned problems, the frequency of the three-phase AC applied to the primary coil was converted using a frequency converter to adjust the acceleration received by the carrier, but the frequency converter was extremely difficult to use. It is expensive.

The object of the present invention is based on the concept of controlling the speed of a conveyor in a linear induction motor by turning on or off the excitation of the primary coil depending on the result of a comparison between a desired running speed and an actual running speed. The object of the present invention is to avoid excessive shocks received by the carriers and collisions between the carriers, regardless of the weight of the carriers, and at a relatively low cost without using a frequency converter.

In order to achieve the above object, the present invention includes a plurality of station parts that are provided with a primary coil that constitutes a linear induction motor and are distributed along a rail, and a secondary coil that constitutes a linear induction motor. A transport body to which a conductor is fixed and moves along the rail; an optical sensor provided in each of the station parts to detect the speed and position of the transport body; A switching means for switching to supply AC voltage, an intermittent means for intermittent supply of three-phase AC voltage to the station section, and a secondary conductor of the carrier on the rail facing each other based on the output signal from the optical sensor. The position of the station section and the speed of the transport body are detected, and the switching means is controlled so as to supply the three-phase AC voltage only to the station section indicated by the position signal, and the speed signal is set to the highest set speed and the lowest set speed. control means for supplying the three-phase alternating current voltage to the station section by controlling the intermittent means so that the speed of the conveying body falls within the range of the maximum set speed and the minimum set speed by comparing with the set speed; A method for controlling a carrier speed of 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 one station section of a transport system using LIM. In FIG. 1, a primary 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 fixed to the lower part of the carrier 5, and is fixed to the secondary conductor by the interaction between the magnetic field from the primary coil group 2 and the overcurrent generated in the secondary conductor 6 by this magnetic field. The carrier runs. In FIG. 1, the primary coil group 2 is wound only on one side of the iron core 1 to simplify the drawing, but it may be wound on both sides.

FIG. 2a is a schematic side view of one embodiment of the station section applied to the speed control system according to the present invention, and FIG. 2b is a partially enlarged perspective view thereof. Second
In Figures a and b, a slit plate 8 is provided at the bottom of the conveyor running on the rail 3, and a secondary conductor 6 that receives force due to the excitation of the primary coil group 2 is fixed under the slit plate 8. There is. Each on rail 3
Two optical sensors 10 ₁ and 10 ₂ are provided near the LIM, and the slits provided in the slit plate 8 are detected by the optical sensors 10 ₁ and 10 ₂ , each consisting of a light emitting section and a light receiving section.

The positions of the optical sensors 10 ₁ and 10 ₂ in the illustrated example indicate a state in which the carrier is stopped at one station, and therefore the optical sensors 10 1 and 10 2
0 ₁ and 10 ₂ are present at both ends of the slit plate 8. That is, when the carrier 5 is stopped at the station, the light emitting section and the light receiving section of each of the optical sensors 10 ₁ and 10 ₂ are shielded by both ends of the slit plate 8 .

Although it is possible to detect the position and speed of the conveyor with one optical sensor corresponding to each station, multiple optical sensors are required because the control range of the primary motor is large relative to the length of the conveyor. Ta.

FIG. 3 is a block circuit diagram showing one embodiment of the speed control system according to the present invention. In Figure 3,
The outputs of the optical sensors 10 ₁ , 10 ₂ , ..., 10 _o provided in n station sections (not shown) are amplified by amplifiers 12 ₁ , 12 ₂ , ..., 12 _o , respectively, and input to the control section 14 . be done. The control unit 14 controls the transport body 5 based on the input output of the optical sensor.
The position and speed shown in FIG. 2 are calculated by the method described later, and speed data corresponding to the calculated position is taken out from the speed setting section 16. Desired speed data is previously set and stored in the speed setting section 16 in correspondence with the position of each station. Also,
If multiple conveyors are running on the rail,
A function may be provided to set the desired speed of the trailing carrier to be smaller than that of the preceding carrier so that the trailing carrier does not collide with the preceding carrier. The control unit 14 compares the calculated traveling speed of the conveyance body with a predetermined value from the speed setting unit 14, and controls the on/off of the switch 18 and the multiplexer 20 based on the result. Three-phase AC from the three-phase AC power supply 20 is supplied to the primary coil of the LIM specified by the multiplexer 20 when the switch 18 is on, and is energized to start, accelerate, decelerate, or stop the carrier.

The speed setting in the speed setting section 16 is arbitrarily set to a desired value for each station.

Even when the carrier 5 enters the station at a certain finite speed, not when it is stopped at the station, the same speed control as described above is performed while the secondary conductor faces the primary coil. receive.

If the speed is not set according to the present invention, the acceleration time due to the traveling magnetic field generated by the primary coil is too long, and the speed of the secondary conductor becomes too large, which may interfere with the Lorentz force due to the traveling magnetic field. In this case, the brakes will be applied to the conveyor, which will hinder the stability of the conveyor. Similarly, in the case of deceleration traveling due to reverse excitation of the traveling magnetic field, if the deceleration time is too long, the speed of the secondary conductor becomes too small, weakening the Lorentz force, and the stability of traveling at the next station may be impaired. be.

Therefore, in the speed setting section 16, it is desirable to set a maximum speed and a minimum speed that do not interfere with the Lorentz force or make it too weak, thereby impairing the running stability of the carrier.

FIG. 4 shows a plurality of speed control methods according to the present invention.
When applied to a conveyance system consisting of LIM,
It is a graph which shows an example of the relationship between the position and speed of a conveyance body. In Fig. 4, LIM ₁ , LIM ₂ ,...,
It is assumed that five LIMs of LIM ₅ are arranged at station positions P ₁ , P ₂ , ..., P ₅ on the rail, respectively, separated from each other, and each LIM (the station to be stopped and the station immediately before it) V _H1 , V _H2 ,
V _H3 and the lowest set speed are V _L1 , V _L2 , and V _L3 .
In the illustrated example, V _H1 to _{V H3} and V _L1 to _{V L3} are each
The same values V _H and V _L are set for LIM ₁ to _{LIM 3} , but
As described above, each station may be set to a different value. Furthermore, although the maximum set speed V _H4 at the station position P ₄ is equal to V _L in the illustrated example, V _H4 may be set to a different value. _P4
The lowest set speed in is V _L4 . Both the highest set speed V _H5 and the lowest set speed V _L5 at the stop station position _P5 may be set to zero. The carrier 5 is stopped in the effective area l ₁ of the primary coil of LIM ₁ of the starting station, and the position of the intermediate station is controlled by the speed control of acceleration and deceleration according to the present invention.
Through P ₂ and P ₃ , stop station LIM ₄ and LIM ₅
The vehicle shall be stopped at position _P5 . In the illustrated example, since the traveling speed V is below V _H during the effective range l ₁ , the primary coil of LIM ₁ continues to accelerate,
When the carrier leaves the effective range _l1 , the excitation of the primary coil is cut off and the vehicle starts coasting. Next, when it enters the effective area l ₂ of the primary coil of LIM ₂ , it is accelerated again because the approach speed is less than V _H in the illustrated example, and when the speed V of the carrier reaches the maximum set speed V _H , the excitation of the primary coil of LIM ₂ is stopped. The vehicle is cut off and becomes coasting again. In P ₁ to P ₃ ,
Although not shown in the figure, if the speed of approach to the effective area is equal to or higher than _VH , the speed is reduced. Thereafter, acceleration, coasting, and deceleration are repeated in the same manner until the desired stopping position _P5 is reached.
The conveyor is stopped. As will be explained in detail later, the position of the station to be stopped (in Fig. 4)
The station position immediately before P ₅ ) (in the figure is
P ₄ ), the maximum set speed V _H4 is set low, so the approach speed to l ₄ is V _H4 as shown in the figure.
In cases above, deceleration control is performed and the maximum set speed V _H4
If the temperature falls below, coasting will occur. Furthermore, since V _H5 =V _L5 =0 at the station position _P5 where the station should be stopped, only the deceleration operation is performed and the station is stopped regardless of the approach speed.

In the example shown in Figure 4, the maximum set speed of LIM ₁ to LIM ₃ is set to a constant value V _H , the maximum set speed of LIM ₄ is set to V _H4 < V _H , and the maximum set speed of LIM ₅ is set to V _H5 and the minimum set speed. Although both speeds V _L5 are set to 0, the set values may be set differently for each station, or the set values for the leading transport body and the trailing transport body may be set differently at one station to prevent collisions. You can also do it. Below, the maximum setting speed and minimum setting at each station are V _H ,
Collectively referred to as _VL .

The relationship between the position and speed from start to stop shown in FIG. 4 is only one example of the embodiment of the present invention, and in reality there may be various modifications. For example, the approach speed to the station may be higher than V _H due to the rail slope or the load on the carrier, etc.
In this case, deceleration control is performed even at the intermediate station. In addition, if the approach speed to the station near the stop position is less than V _L , or if the speed is insufficient for control at the next station, etc.
Performs acceleration control.

A more detailed explanation of the processing in the control unit 14 will be given below.

Determination operation of the stopped state of the conveyor As shown in FIGS. 2a and 2b, the optical sensor 10
₁ and 10 ₂ are arranged so as to be shielded from each other at both ends of the slit plate 8. This arrangement makes it possible to determine whether the carrier is stopped at the station. That is, in FIGS. 5 and 6,
When the optical sensors 10 ₁ and 10 ₂ are both turned on (sensor shielding state) in step 51, and the shielding state continues for a certain period of time T, the conveying body is equipped with the optical sensors 10 ₁ and 10 ₂ . It is determined that the station is stopped at the station that is located.

Detection operation of the speed of the transport body The speed of the transport body is detected by the controller 14 detecting the width of a pulse obtained from the output of the sensor. If there is one sensor in one station, it is possible to detect the speed of the transport object passing through it, but since the range in which the speed can be detected over the moving distance of the transport object is narrow with one sensor, as shown in Fig. 2. As shown in a and b, optical sensors 10 ₁ and 10 ₂ are arranged at both ends of the slit plate 8. By providing two sensors in this way, the speed can be detected over a distance twice the length of the conveyor, as shown in Figure 7, and the detection accuracy can therefore be increased. can.

FIG. 8 is an explanatory diagram of a method of calculating the speed of the conveyor. When the conveyor is passing the sensor 10 _o ,
An output pulse as shown in FIG. 8 can be obtained. If the length of the slit plate 8 of the conveyor is s, then
The speed V of the conveyor has a relationship of V=s/T _j with respect to the period T _j per slit. Therefore,
By measuring the period T _j , the speed of the carrier can be measured.

In the control section 14, when detecting the speed, it is performed by directly comparing T _j with a predetermined value, without relying on the above equation. That is, the value T _s corresponding to the speed to be compared is calculated in advance from the above equation, and the magnitude of the speed is determined by comparing T _s and T _j . The speed setting section 16 stores a speed setting value _Ts . If T _s < T _j , the speed of the carrier is smaller than the predetermined value, if T _s = T _j , the velocity of the carrier is equal to the predetermined value, and if T _s > T _j , the velocity of the carrier is less than the predetermined value. Greater than a predetermined value.

Detection of the station to which the carrier faces and detection of the position of the carrier in the station FIG. 9 is a flowchart illustrating the position of the station to which the carrier faces and a method for detecting the position in the station. In the figure, when a carrier enters a certain station, depending on the direction of movement of the carrier, either sensor 10 _o or 10 _o+1 fixed to that station is turned on first (step 1). 91, 92). For the sensor that was previously turned on, it is determined whether or not the next pulse will be generated within a specified time by turning off and then turning on again after the previous turning on (steps 93 and 94). This step is provided to distinguish between pulses due to the entrance of the carrier and pulses due to noise. Step 93 or
If it is determined in step 95 that there is a pulse, step 94 or
At 96, increase the pulse count by one.

Escape of the carrier from the station can be detected when the number of pulses reaches a predetermined number. That is, in step 95 it is determined whether the pulse count has reached a specified number of pulses, and if so, in step 96 it is determined that the carrier has passed through that station. If the predetermined number of pulses has not been reached in step 95, it is determined in step 97 whether there is a next pulse within the predetermined time, and if not, the process proceeds to step 98.
It is assumed that the station's sensor is abnormal and the process is interrupted. In this case, for convenience of processing, it is assumed that the conveyance object has passed the station, the sensor of the next station is noted, and the process moves on to the next station. If there is a next pulse within the specified time in step 97, the pulse count is incremented by one in step 99, and the pulse count is incremented by one in step 95.
Return to

Detection of the opposing station and detection of the position of the transport body described above are performed by placing sensors at both ends of each station, but the range that can be detected by one sensor is limited to the length of the transport body. Since the length of the station is longer than twice the length of the carrier, the position of the carrier cannot be accurately detected. In order to avoid this, by appropriately providing three or more sensors (not shown) in each station and switching their outputs using a multiplexer, it is possible to ensure the detection of the position of the carrier in each station.

Details of the control unit 14 FIG. 10 is a block diagram showing the configuration of the control unit 14. As shown in FIG.

In the figure, the control unit 14 controls the multiplexers 101-1 to 101-5 and the multiplexer 10.
2, pulse number counter 103, and speed detection section 1
04, a station number register 105, and a microprocessor unit (MPU) 106. Multiplexers 101-1 to 101-5 correspond to LIM ₁ to LIM ₅ , respectively, and each
In response to a switching signal from the MPU, the output of one of the two sensors provided in the LIM is selected and delivered to the multiplexer 102. The multiplexer 102 has a station number register 105.
Depending on the station number set in
Corresponding multiplexers 101-1 to 101-5
Select and output one output. The pulse number counter 103 counts the number of pulses from the optical sensor obtained at the output of the multiplexer 102, and provides the counted value to the MPU 106 as a position signal.
The speed detection unit 104 detects the speed of the carrier from the pulse length obtained from the output of the multiplexer 102, and provides the detected speed to the MPU 106 as a speed signal. MPU
106 outputs the number of the station facing the carrier based on the position signal from the pulse number counter 103, and the station number register 10
Enter 5.

The MPU 106 also detects the speed of the carrier by comparing the reference time T _si set in the speed setting section 16 with the time T _i corresponding to the speed signal obtained from the speed detection section 105 . The detected station number is input to the multiplexer 20 (see Figure 3), which causes LIM ₁ to
One of LIM ₅ is selected. Also, based on the detected speed signal and position signal, MPU1
06 generates a motor on/off control signal to control the on/off of switch 18 (see FIG. 3).

Outline of control from start to stop of conveyor body FIG. 11 is a generalized flowchart for explaining control from start to stop of the conveyor body illustrated in FIG. 4. In FIG. 11, as a prerequisite, before starting the starting operation, the position of the starting station, the position of the stopping station, and the maximum setting speed V _H and minimum setting speed V _L of each station between the starting station and the stopping station are determined in advance. is determined and set in the position register (not shown) in the MPU 106 and the speed setting unit 16.

In step 111, a starting operation is performed at the starting station based on an operator's instruction or a mechanical or electrical trigger. Since the carrier is stopped at any station, the carrier to be controlled is stopped at the starting station before the starting operation. When a plurality of carriers are present on the rail, the starting operation is controlled by retracting other carriers from the rail or setting different speeds for each carrier to avoid collisions. The control for retracting the conveyance body out of the rails is outside the scope of the present invention, and will not be described in detail.

Next, except for the stop station and a predetermined number of stations immediately before it, speed control is performed at each station so that the speed of the transport body is between the maximum set speed _VH and the minimum set speed _VL for that station. In the embodiment shown in FIG. 11, a stop operation is performed at the stop station (step 116), a deceleration operation is performed at the station one station before the stop station (step 115), and an acceleration is performed at an intermediate station. There is. However, at each station, the speed is controlled to be between _VH and _VL (steps 114 and 115). For example, if the approach speed to the intermediate station is higher than _VH due to the rail slope, loaded mass, etc., deceleration control is performed in accordance with the above proviso.

Details of the Starting Operation of the Transporting Body FIG. 12 is a flowchart illustrating in more detail the starting operation of the transporting body in step 111 in the flowchart of FIG. In Fig. 12, when the motor is first turned on in response to a starting command in either the left or right direction (step 121), the optical sensor on the starting direction side repeats on and off, thereby generating a pulse (step 122). . The pulse number counter 103 in the control unit 14 counts this number of pulses (step 123), and based on the count value, determines whether the carrier is facing the motor or has moved outside the motor (step 124). . If the station is outside the motor, the motor is turned off and control at that station is ended (step 125).
If it is facing the motor, the speed of the conveyor is further detected from the pulse width (step 126), and that speed is the maximum set speed V _H at that station.
Speed control is performed as follows. When the speed exceeds the maximum set speed _VH , the motor is turned off (step 127) and coasting is performed. Then, pulses from the sensor are counted until the conveyance object exits the motor (steps 128, 129), and once it exits the motor (step 130), control at the starting station is terminated.

Details of acceleration/deceleration control Figure 13 shows steps 113 to 11 in Figure 11.
116 is a flowchart explaining the process in more detail.
With reference to FIG. 13, an explanation will be given of acceleration/deceleration control for controlling the speed of the transport body to be between the maximum set speed _VH and the minimum set speed _VL at each station after the transport body starts. That is, the acceleration/deceleration control shown in FIG. 13 is, for example, control at positions P ₁ to P ₅ in FIG. 4.

In FIG. 13, the number of pulses is counted in steps 131 and 132, and the station position can be determined from the counted value, so in step 133,
It is determined whether the station position is under acceleration control or deceleration control. Whether the control is acceleration control or deceleration control is determined in advance depending on the station position. Acceleration control is normally performed on flat areas, but deceleration control is performed at stations near the stop station.

If acceleration control is determined in step 133, the approach speed is compared with _VH in step 134, and if it is less than _VH , the motor is turned on for acceleration in step 135.
If the approach speed is higher than _VH for some reason (station at the bottom of a downhill slope, etc.),
At step 136, the motor is turned on to the deceleration side.

Next, in steps 137 to 139, it is determined whether the carrier is within the control range (effective range) of the motor of that station, and if it is within the control range of the motor, the transport is accelerated in step 135 in step 140. If the conveyor is accelerating, the speed of the conveyor is determined in steps 137 to 142.
Continue turning the motor on to the acceleration side until V _H or higher. If it is determined in step 140 that the vehicle is being decelerated, the motor continues to be turned on to the deceleration side in steps 137 to 140 and steps 143 and 144 until the speed of the carrier becomes below _VL . In any case, if the motor is turned off, the vehicle will coast.

When it is determined in step 133 that deceleration control is required,
At step 146, the approach speed is compared with V _L , and if it is equal to or higher than V _L , the motor is turned on for deceleration at step 147. If the approach speed is less than V _L , it will be difficult to control the speed at the next station, so the motor is turned on to the acceleration side in step 148 even though it is under deceleration control.

Next, in steps 149 to 151, it is determined whether the carrier is within the control range of the motor of the station, and if it is within the control range of the motor, then in step 152,
Are you accelerating step 147?
148 is being decelerated, and if it is being decelerated, the motor continues to be turned on to the deceleration side in steps 149 to 154 until the speed of the carrier becomes below _VL . Further, when it is determined in step 152 that the conveyor is being accelerated, it continues to accelerate in steps 149 to 151 and steps 155 and 156 until the speed of the carrier becomes equal to or less than _VL .

If it is determined in step 139 or 151 that the carrier is outside the motor control range, the motor is turned off unless the vehicle is coasting.

Details of Stop Control FIG. 14 is a detailed flowchart of step 116 in FIG. 11. As shown in the figure, when the conveyor approaches the stop station, the motor continues to be turned on in the opposite direction to the approach direction until the speed reaches zero, and when the speed reaches zero, the motor is turned off and the conveyor to stop.

Details of the operation from starting to stopping in FIG. 4 When starting the carrier from the starting station position _P1 in FIG. 4, the operation is performed according to FIG. 12. That is, the MPU 106 inside the control section 14 issues control signals for the switch 18 and the multiplexer 20 according to the starting direction according to an operator's command or an electrical/mechanical trigger, thereby turning on LIM ₁ .

MPU106 is station number register 10
5 is prewritten with the number 1 corresponding to LIM ₁ , so the multiplexer 102 selects the outputs of the sensors 10 ₁ and 10 ₂ of LIM ₁ as the sensor signals. This sensor signal is sent to the pulse number counter 10
3 and are input to the speed detection unit 104, and are input to the MPU 106 as a position signal and a speed signal, respectively.
When the MPU 106 detects escape of the carrier from LIM ₁ based on the number of pulses of the sensor, it turns off LIM ₁ (step 125) and the carrier enters the coasting state. If the speed of LIM ₁ reaches V _H1 , at that point LIM ₁ is turned off and the carrier is brought into a coasting state (step 127). In this case, since the carrier is within LIM ₁ , the start process is completed after confirming that it has escaped to the outside of the motor based on the number of pulses (steps 128 to 130).

After completing the start processing, the conveyance body coasts toward _{LIM 2} of P2, but the MPU 106 of the control unit 14 writes the number ₂ corresponding to P2 in the station number register 105 and conveys it while checking the sensors 10 ₃ and 10 ₄ . Waiting for the body to enter. When the carrier reaches the sensor of _P2 and blocks the sensor, MPU1
06 detects the entry of the carrier, and can detect the speed from the width of the pulse (by the speed detection unit 104). In LIM ₂ of P ₂ , in order to perform acceleration, V _H2 and the speed of the carrier are compared, and if it is slower than V _H2 , acceleration is performed. When the conveyor is within the control range of LIM ₂ , acceleration is performed until the speed reaches V _H2 . The carrier is LIM ₂
Sensor pulses are obtained as the conveyor moves through the slit plate, but since the sensors 10 ₃ and 10 ₄ are arranged so as to span both ends of the slit plate of the carrier, when the number of pulses equal to the number of slits is input, the multiplexer Switch the sensor. (In the present invention, the sensor is switched from 10 ₃ to 10 ₄ ) By switching the sensor, it is possible to monitor the state of the conveyor over a wide range. The MPU unit also detects whether the conveyor is inside the motor based on the pulse count number. If the conveyor leaves the control range of LIM ₂ ,
Even if LIM ₂ is turned on and accelerating, LIM ₂ is turned off and the conveyor is placed in a coasting state. The carrier reaches P ₃ while coasting, but the processing at P ₃ is the same as that at P ₂ .

At _P4 , deceleration is performed so that the stopping operation is performed smoothly at _P5 . During deceleration, after detecting the approach of the transport object, LIM ₄ is excited in the direction of deceleration of the transport object,
The acceleration is the same as in P ₂ to _{P 3} except that the speed is compared with V _L4 and LIM ₄ is turned off when the speed becomes less than V _L4 .

In the process of stopping the transport object at _P5 , after detecting the coasting transport object, V _H5 = V _L5 = 0, so regardless of the approach speed, LIM ₅ is turned on in the opposite direction to the traveling direction, and the speed becomes sufficiently small. (as close to zero as possible) and turn off LIM ₅ .
After that, positioning is performed by a method such as mechanically sandwiching the carrier.

Other means may be used to detect the position and velocity, such as bar codes and reflective optical sensors, magnetic stripes and magnetic heads, inductors, etc.

In the embodiments of the present invention described above, the speed control method is realized by software using a microcomputer or the like, but it can also be realized by hardware.

As is clear from the above description, according to the present invention, it is possible to control the speed of the carrier of a linear induction motor at a relatively low cost without using a known number converter, and the carrier is lightweight. This also makes it possible to prevent the conveyors from receiving excessive shock during acceleration and from colliding with each other.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing one station section of a conveyance system using a linear induction motor, and FIG. 2 a shows an embodiment of the station section applied to the speed control method according to the present invention. A schematic side view, FIG. 2b is a partially enlarged perspective view of FIG. 2a, and FIG.
A block circuit diagram showing an embodiment, FIG. 4 is a graph showing an example of the relationship between the position and speed of a conveying body when the speed control method according to the present invention is applied, and FIG. 5 is a diagram showing a conveying body according to an embodiment of the present invention. 6 is a time chart explaining the determination of the stopped state. FIG. 7 is a flowchart illustrating the determination of the stop state. FIG. 7 is a flowchart illustrating the determination of the stop state. A time chart explaining the advantages, FIG. 8 is an explanatory diagram of the calculation method of the speed of the conveying body in the embodiment of the present invention, and FIG. 9 is a diagram showing the position of the station facing the conveying body in the embodiment of the present invention and the position at that station. FIG. 10 is a flowchart explaining the position detection method; FIG. 10 is a block diagram showing the configuration of the control section in the embodiment of the present invention; FIG.
Figure 1 is a flowchart showing an outline of control from start to stop of the conveyor in an embodiment of the present invention.
FIG. 2 is a flowchart explaining the details of the starting operation of the carrier in the embodiment of the present invention, FIG. 13 is a flowchart explaining the details of acceleration/deceleration control of the carrier in the embodiment of the present invention, and FIG. It is a flowchart explaining details of stop control of a conveyance body in an example of the present invention. In the figure, 1...iron core, 2...primary coil,
3...Rail, 4...Wheel, 5...Transportation body, 6...
... Secondary conductor, 8 ... Slit plate, 10 ... Optical sensor, 14 ... Control section, 16 ... Speed setting section, 1
8...Switch, 20...Three-phase AC power supply, 24 ₁ ,
24 ₂ ,...24 _o ...Linear induction motor, V _H1 ~ V _H5 ... Maximum set speed, V _L1 ~ V _L5 ...
...This is the minimum set speed.

Claims (1)

[Scope of Claims] 1. A plurality of station parts each having a primary coil constituting a linear induction motor and distributed along the rail, and a secondary conductor constituting the linear induction motor are fixedly attached to each other, a transport body that moves along the station; an optical sensor provided in each of the station parts to detect the speed and position of the transport body; and a three-phase AC voltage configured to supply one of the plurality of station parts a switching means for switching the supply of the three-phase AC voltage to the station section; and an intermittent means for switching on and off the supply of the three-phase AC voltage to the station section; Detecting the speed of the carrier, controlling the switching means so as to supply the three-phase AC voltage only to the station indicated by the position signal, and comparing the speed signal with a maximum set speed and a minimum set speed. and control means for supplying the three-phase AC voltage to the station section by controlling the intermittent means so that the speed of the carrier falls within the range of the maximum set speed and the minimum set speed. A conveyor speed control method for a linear induction motor.