JPH0652961B2 - Linear motor type transport device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a linear motor type transfer device used for transferring articles in factories, warehouses, etc., and particularly, to prevent the carrier from being rapidly accelerated at the time of starting. The present invention relates to a linear motor type transport device.

"Prior Art" Conventionally, a linear motor type transfer device using a one-sided linear induction motor (hereinafter abbreviated as LIM) as a drive source is known as a transfer means in a product assembly transfer line or the like.

FIGS. 4 (a) and 4 (b) are diagrams showing an external configuration of a conventional linear motor type conveying device. In these figures, 1 is a rail laid along the transport path, 2 is a carrier that is supported by four rotatable wheels 3, 3, ... And runs on the rail 1. On this carrier 2, The objects to be transported 4 are loaded. M _{1 to} M _n are arranged along the rail 1 at predetermined intervals and are responsible for generating a traveling magnetic field.
The primary side coils 5 are attached to the lower surface of the carrier 2 and are LIM secondary side conductors that face the primary side coils M _{1 to} M _{n of} the LIM with a vertical gap. Reference numeral 6 is a slit plate attached to the side portion of the carrier 2, and a plurality of slits are formed at equal intervals depending on the traveling method of the carrier 2. In S _{1 to} S _n, the carrier 2 has each primary coil M.
_{1 to} M _n is a speed sensor that detects a speed when passing over the slit plate 6, and is composed of a transmissive photosensor that detects light transmitted through each slit of the slit plate 6.
Speed signal SP _{1 of} pulse frequency corresponding to the passing speed of
Output SP _n . Further, P _{1 to} P _n are carrier detection sensors for detecting whether or not the carrier 2 is present above the primary side coils M _{1 to} M _n , and are constituted by a reflection type photo sensor and detect the carrier 2. In that case, the carrier detection signals C _{1 to} C _n are output. Then, in the illustrated state, when the primary coil M ₁ is excited, the traveling magnetic field generated on the primary M ₁ causes thrust in the direction of the arrow to act on the secondary conductor 5, which causes the carrier 2 to move. Start traveling in the direction of the arrow. Then
When the carrier 2 is accelerated and leaves the primary coil M _1, it travels up to the next primary coil M ₂ by inertia, and during this time, the carrier 2 has a running resistance caused by frictional resistance with the rail 1 or the like. The vehicle runs at a slightly reduced speed.
Then, when the carrier 2 reaches the primary coil M ₂ , it is accelerated again. In this way, the carrier 2 is accelerated in each section that vertically overlaps with each of the primary side coils M _{1 to} M _n, and travels while being slightly decelerated in the other sections.

Next, FIG. 5 is a block diagram showing the configuration of a conventional linear motor type transport device. In this figure, 7 is a speed command signal Sa based on the carrier detection signals C _{1 to} C _n.
For outputting the speed detection signals SP _{1 to} SP
A frequency / voltage converter that converts the pulse frequency of _n into a voltage signal and outputs it as a speed feedback signal Sf, and 9 is a subtraction circuit that subtracts the speed feedback signal Sf from the speed command signal Sa, the output of which is the control signal Sd. It is output to the power control device 10. This power control device 10
Is composed of a thyristor, and is a three-phase AC power supply 1
The control signal S controls the voltage of the three-phase AC supplied from
The three-phase alternating current of the voltage corresponding to d is applied to the primary side coils M _{1 to} M _n.
To supply to each. This allows carrier 2
Is reached on the primary side coils M _{1 to} M _n , the vehicle is accelerated to a speed corresponding to the speed command signal Sa.

[Problems to be Solved by the Invention] In the linear motor conveyance device described above, when the carrier 2 stopped on the primary coil M ₁ is started, the control device 7 controls the speed as shown in FIG. The command signal Sa is output. That is, the control device 7, with 0 [V] starting t _0, the start time t ₀ after the setting value L 0 [V]
Up to [V], a so-called ramp function-like speed command signal Sa that rises at a constant rate of change (slope) in proportion to time is output. In this case, the speed of the carrier 2 changes as shown by the alternate long and short dash line K in the figure, and the carrier 2 receives the speed command signal during the period from the start time t ₀ to the time point t ₁ when the carrier 2 leaves the primary coil M _1. In the period from the time t ₁ when the vehicle leaves Sa on the primary coil M ₁ to the time t ₂ when the vehicle reaches the next primary coil M ₂ , the vehicle is slightly decelerated by the traveling resistance. On the other hand, the speed command signal Sa output from the control device 7 rises at a constant rate of change even during the time points t _{1 to} t ₂ described above. Therefore, at the time point t ₂ when the carrier 2 reaches the primary coil M ₂ , the difference between the speed command signal Sa and the speed feedback signal Sf corresponding to the speed of the carrier 2 is indicated by D in FIG. To be extremely large. Then, the primary coil M ₂
Is driven by electric power corresponding to the control signal Sd which is the difference between the speed command signal Sa and the speed feedback signal Sf, the carrier 2 is rapidly accelerated (time t _{2 in} FIG. 6).
~ T ₃ period). As a result, if the transported object 4 receives an impact and the transported object 4 is a fragile article, there is a risk of damage.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a linear motor type transfer device in which a carrier is prevented from being rapidly accelerated at the time of starting.

"Means for Solving Problems" The present invention is arranged at predetermined intervals along a conveyance path,
A plurality of primary side coils for generating a traveling magnetic field, a carrier having a secondary side conductor to which thrust is sequentially applied by these primary side coils, and a speed of the carrier is detected,
A speed detection unit that outputs the detection result as a speed feedback signal, and a power control unit that supplies electric power determined based on a deviation signal between the speed command signal and the speed feedback signal to each of the temporary coils. In a linear motor type conveyance device that sequentially accelerates the carrier in the traveling direction to travel, carrier detection means for detecting whether or not the carrier is present on each of the primary coils, and the carrier is started. To a steady speed, the period during which the carrier is detected by the carrier detection unit, the rate is increased at a predetermined change rate, and the period in which the carrier is not detected by the carrier detection unit In the case of, the speed decrease due to the running resistance of the carrier is slightly reduced. It is characterized by comprising a speed command signal generating means for outputting a speed command signal is not directly changed.

"Action" In the period from the start of the carrier to the steady speed, in the period in which the carrier is located above the primary coil, the speed command signal rises at a predetermined rate of change,
Next, after the carrier has passed over the primary coil, the speed command signal slightly decreases or does not change as much as the speed decrease due to the running resistance of the carrier, so that the speed command signal that substantially corresponds to the actual speed change to the carrier. As a result, when the carrier reaches the next primary coil, the difference between the speed command signal and the speed feedback signal corresponding to the speed of the carrier does not become large, and the carrier is accelerated rapidly. There is no.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a linear motor type conveying device according to an embodiment of the present invention. In this figure, parts corresponding to the respective parts in FIG. To do. In this figure, the difference from that shown in FIG. 5 is that a speed command signal generating circuit 12 having the configuration shown in FIG. 2 is provided in the control device 7a.

Hereinafter, the speed command signal generating circuit 12 will be described in detail with reference to FIG. In this figure, 14 is a field-effect transistor (FET), its gate connected to the terminal T _1, the drive signal Son through the terminal T ₁ is turned on when supplied. The terminal T ₂ is connected to the inverting input terminal of an operational amplifier (hereinafter abbreviated as OP amplifier) 17 via resistors 15 and 16 connected in series, and both ends of the resistor 16 are connected to the source and drain of the transistor 14, respectively. It is connected. In this case, the resistance value R ₂ of the resistor 15 is larger than the resistance value R ₁ of the resistor 16. A capacitor C is inserted between the inverting input terminal and the output terminal of the OP amplifier 18, and the non-inverting input terminal of the OP amplifier 18 is grounded. And the control device 7a
, At the time of the carrier 2 start, when the carrier detection signal C ₁ -C _n is supplied, supplies a driving signal Son to the terminal T _1, applying a constant voltage Vs to the terminal T _2, also, the carrier When the detection signals C _{1 to} C _n are no longer supplied, the supply of the drive signal Son to the terminal T ₁ is stopped, and the application of the constant voltage Vs to the terminal T ₂ is stopped.

Here, the drive signal Son is supplied to the terminal T ₁ , and the terminal T ₂
When a constant voltage Vs is applied to the transistor 14, the transistor 14 is turned on and the two ends of the resistor 16 are electrically connected to each other.
A circuit including the resistor 15, the OP amplifier 17, and the capacitor 18 functions as an integrating circuit. In this case, the voltage Vo at the output end of the OP amplifier 18 changes as shown by the following equation, and decreases at a constant rate of change determined by the capacitance C of the capacitor 18 and the resistance value R ₁ of the resistor 15.

On the other hand, when the drive signal Son is not supplied to the terminal T _{1 and the} constant voltage Vs is not applied to the terminal T ₂ , the transistor 14 is turned off, which causes the combined resistance of the resistors 15 and 16 (R ₁ + R ₂ ) and the capacitance C of the capacitor 18, the voltage V ₀ gradually decreases because the capacitor 18 discharges according to a time constant. In this case, the combined resistance (R ₁ + R ₂ ) and the value of the capacitance C correspond to the speed reduction due to the traveling resistance when the carrier 2 coasts without receiving thrust from each of the primary side coils M _{1 to} M _n. And set appropriately.

The voltage Vo at the output end of the OP amplifier 17 which changes in this way
Is inverted in polarity by an inverter 18, and is output from the terminal T ₃ to the subtraction circuit 9 as a speed command signal Sa ₁ .

Next, the operation of the linear motor type transport device having the above-described configuration will be described. FIG. 3 is a diagram showing changes in the speed command signal Sa ₁ when the carrier 2 stopped on the primary coil M ₁ is started, and time is set on the horizontal axis.

First, at the start time t ₀ , the carrier detection sensor P ₁
The carrier detection signal C ₁ output from the controller 7a
Accordingly, the control device 7a supplies the drive signal Son to the terminal T ₁ of the speed command signal generating circuit 12 and applies the constant voltage Vs to the terminal T ₂ . Then, the transistor 14 is turned on, and the speed command signal generation circuit 12
A speed command signal Sa ₁ that rises at a constant rate of change determined by the capacitance C of the capacitor 18 and the resistance value R ₁ of the resistor 15 is output from the terminal T _{3 of the} . As a result, carrier 2 is at time t _0.
During the period from t ₁ to t _1, the vehicle speed is gently accelerated following the speed command signal Sa ₁ .

Then, after the time point t ₁ when the carrier 2 is separated from the primary coil M ₁ , the carrier detection signal C ₁ is no longer supplied to the control device 7a, which supplies the drive signal Son to the terminal T ₁ and the terminal T ₁ . The application of the constant voltage Vs to T ₂ is cut off. Then, transistor 1
4 is turned off, and the terminal T _{3 of the} speed command signal generation circuit 12
Therefore, the speed command signal Sa ₁ that decreases at a constant rate of change determined by the combined resistance (R ₁ + R ₂ ) of the resistors 15 and 16 and the capacitance C of the capacitor 18 is output. As a result, time point
During the period from t _{1 to} t ₂ , the speed command signal Sa ₁ gradually decreases corresponding to the decrease in speed due to the running resistance of the carrier 2.

Next, when the carrier 2 reaches the primary coil M ₂ ,
This time, the carrier detection signal C ₂ output from the carrier detection sensor P ₂ is supplied to the control device 7a, which again causes the terminal T _{3 of} the speed command signal generation circuit 12 to
A speed command signal Sa ₁ that rises at a constant rate of change determined by the capacitance C of the capacitor 18 and the resistance value R ₁ of the resistor 15 is output. As a result, the period of time t ₂ ~t _3, the carrier 2 is gently accelerated to follow the speed command signal Sa _1.

Thus, at the time point t ₂ when the carrier 2 reaches the primary side coil M ₂ , the speed command signal Sa ₁ decreases substantially corresponding to the amount of speed decrease due to the running resistance of the carrier 2. The difference between Sa ₁ and the speed feedback signal Sf corresponding to the actual speed of the carrier 2 does not become large, and the carrier 2 is not accelerated rapidly as in the conventional case.

In the above-described embodiment, the carrier 2 passes through the primary coil M ₁ and then the next primary coil M ₂
Although the speed command signal Sa ₁ is gradually decreased in a period corresponding to the speed decrease amount due to the traveling resistance of the carrier 2 until reaching, the speed command signal Sa ₁ may be left unchanged. Absent.

[Advantages of the Invention] As described above, according to the present invention, carrier detecting means for detecting whether or not a carrier is present on each primary coil, and a constant speed from the start of the carrier until a steady speed is reached. During the period in which the carrier is detected by the carrier detecting means, the rate of rise is increased at a predetermined change rate, and in the period in which the carrier is not detected by the carrier detecting means, Since the speed command signal generating means for outputting a speed command signal that slightly decreases or does not change as much as the speed decrease due to running resistance is provided, a speed command signal substantially corresponding to the actual speed change of the carrier can be obtained. , As in the past, the difference between the speed command signal and the speed feedback signal becomes large, and the carrier is suddenly added. Even if a fragile article is loaded on the carrier without being accelerated, the effect that the loaded article is not likely to be damaged by the impact during acceleration is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention,
2 is a circuit diagram showing the configuration of the speed command signal generating circuit 12 in the same embodiment, FIG. 3 is a view showing changes in the speed command signal Sa ₁ in the same embodiment, and FIGS. 4 (a) and 4 (b). Is a side view and a front view showing an external configuration of a conventional linear motor type transport device, FIG. 5 is a block diagram showing an electrical configuration of the linear motor type transport device, and FIG. 6 is an operation of the linear motor type transport device. It is a figure which shows the relationship with the speed command signal Sa. M _{1 to} M _n ... Primary side coil, S _{1 to} S _n ... Speed sensor, P _{1 to} P _n ... Carrier detection sensor (carrier detection means), 2 ... Carrier, 7 a ... Control device, 8
... F / V converter, 9 ... subtraction circuit, 10 ... power control device, 12 ... speed command signal generation circuit, 14 ... field effect transistor, 15,16 ... resistor, 17 ... OP amplifier, 18 ... Capacitor.

Claims (1)

[Claims] 1. Arranged at predetermined intervals along a conveying path,
A plurality of primary side coils for generating a traveling magnetic field, a carrier having a secondary side conductor to which thrust is sequentially applied by these primary side coils, and a speed of the carrier is detected,
A speed detection unit that outputs the detection result as a speed feedback signal, and a power control unit that supplies electric power determined based on a deviation signal between the speed command signal and the speed feedback signal to each of the temporary coils. A linear motor type transporting device for sequentially accelerating and traveling the carrier in the traveling direction, carrier detection means for detecting whether or not the carrier is present on each of the temporary coils, and the carrier is started. To a steady speed, the period during which the carrier is detected by the carrier detection unit, the rate is increased at a predetermined change rate, and the period in which the carrier is not detected by the carrier detection unit In the above, a slight decrease due to the speed reduction due to the running resistance of the carrier, Ku is a linear motor type conveying apparatus characterized by comprising a speed command signal generating means for outputting a speed command signal is not directly changed.