JPH0824431B2 - Linear motor transport device - Google Patents

Description

Description: “Industrial application field” The present invention relates to a linear motor conveyance device in which an object to be conveyed is driven by a linear motor.

"Prior Art" FIG. 4 is a block diagram showing a configuration of a conventional linear motor conveyance device. In this figure, 1 is a three-phase AC power supply,
Reference numeral 2 is a power conversion device using a thyristor, and 3,3 ... are linear motor primary sides that generate a traveling magnetic field by the three-phase AC power output from the power conversion device 2. As shown in FIG. 5, the primary sides of the linear motors 3, 3, ... Are arranged at regular intervals in the conveying path. In FIG. 5, reference numeral 4 denotes an object to be conveyed, and the secondary conductor 4a of the linear motor is attached to the lower surface thereof. When the linear motor primary side 3 is excited, the transported object 4 travels by receiving a thrust due to its traveling magnetic field, and when it reaches the next linear motor primary side 3,
The same secondary side 3 again receives thrust, and thereafter the vehicle travels by repeating this process. In FIG. 4, Sa is a speed command signal output from a control device (not shown), and Sf is a speed feedback signal output from a speed detector (not shown) that detects the speed of the transported object 4. 5 is a subtraction circuit for subtracting the signal Sf from the signal Sa, the output of which is the deviation signal Sd
Is output to the power conversion device 2. The power converter 2 controls the phase of the internal thyristor with a phase angle that makes the deviation signal Sd zero. As a result, the transported object 4 travels at the speed corresponding to the speed command signal Sa.

[Problems to be Solved by the Invention] In the linear motor conveying device described above, the object to be conveyed 4 is accelerated by receiving thrust only at the position of the linear motor primary side 3, and the primary side 3 and the primary side 3 are accelerated. During the period, the vehicle is decelerated due to the running resistance of the transport path. That is, the transported object 4
5 changes as shown by the solid line L in FIG. In addition,
The broken line shows the speed command signal Sa. As a result, the magnetism when the transported object 4 reaches the position on the primary side 3 has a considerable difference between the signal Sa and the signal Sf. Then, the primary side 3 receives the signal Sa
Since it is driven by the electric power corresponding to the deviation signal Sd from Sf, the transported object 4 is suddenly subjected to a large thrust at the position of the primary side 3 especially when the difference between the signals Sa and Sf is large. As a result, when the transported object 4 holds fragile objects such as glass inside, they may be damaged.

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 conveyance device in which a large thrust force is not suddenly applied to a conveyed object.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention is directed to a plurality of linear motor primary sides arranged at a predetermined interval in a conveying path and a conveyed object traveling on the conveying path. A linear motor secondary side conductor that is provided in the object and is driven by each of the plurality of linear motor primary sides, and a speed detection unit that detects the traveling speed of the transported object and outputs the speed signal as a speed signal,
Each time the conveyed object passes through each of the linear motor primary sides, the power supplied to each of the linear motor primary sides is controlled so that the speed command signal supplied from the outside and the speed signal match. Then, in the linear motor transport device for traveling the transported object, when the transported object reaches each of the linear motor primary side, after reducing the speed command signal according to the speed signal, It is characterized by including a speed command correction circuit that is gradually increased and returned to the original state.

[Operation] According to this configuration, each time the conveyed object reaches the primary side of the linear motor, the speed command signal is corrected by the speed command correction circuit so as to be gradually decreased after being reduced according to the speed signal. As a result, when the transported object is decelerated between the primary side of the linear motor and becomes too slow with respect to the speed command signal before correction, the transported object is not abruptly generated with a large thrust force. The speed control of the object is performed.

[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 conveying apparatus according to the same embodiment. In this figure, parts corresponding to the respective parts in FIG. 4 are assigned the same reference numerals and explanations thereof are omitted. The embodiment shown in this figure differs from that shown in FIG. 4 in that a speed command correction circuit 6 is provided. The details of the speed command correction circuit 6 are shown in FIG. In the figure, T1 and T2 are input terminals to which the speed command signal Sa and the speed feedback signal Sf are supplied, respectively.

The speed command signal Sa is supplied to the addition input terminal of the subtraction circuit 15 and the connection point A which is the input of the amplifier 10 via the resistor 7, while the speed feedback signal Sf has its polarity inverted by the inverter 8. After that, it is supplied to the connection point A via the resistor 9.

The output of the amplifier 10 is fed back by the resistor 11 and supplied to the differentiating circuit 14 including the resistor 12 and the capacitor 13. Here, the resistance values of the resistors 7 and 9 are the same, the resistance value of the resistor 11 is the amplification factor of the amplifier 10,
It is set to be slightly smaller than "1".

Thereby, the speed feedback signal Sf is subtracted from the speed command signal Sa, a signal Sb obtained by attenuating the speed feedback signal Sf is output by the amplifier 10, a signal Sc obtained by differentiating the signal Sb is output by the differentiating circuit 14, and a subtracting circuit is provided. Supplied to 15 subtraction inputs.

Then, in the subtraction circuit 15, from the speed command signal Sa to the signal Sc
Is subtracted, and the corrected speed command signal Sa1 is output from the output terminal T3.

Next, the operation of the linear motor carrying device having the above-described configuration will be described with reference to FIG. FIG. 3 is a diagram showing changes in each signal related to speed control of the linear motor conveyance device, in which time is set on the horizontal axis and signal level is set on the vertical axis. In the figure, t1 indicates the drive start point of the linear motor, and before reaching the drive start point t1,
The actual speed of the transported object is lower than the commanded speed due to the traveling resistance. Therefore, as shown in (b) of the figure, immediately before the driving start point t1, the level of the speed feedback signal Sf is ) It is lower than the speed command signal Sa indicated by. Now, let this difference be I1. When the conveyed object reaches the linear motor primary side 3 at the driving start point t1, the speed command signal Sa
Signal Sb that attenuates the difference between the speed feedback signal Sf and
Is output from the amplifier 10. The level I2 of the signal Sb (see FIG. 3C) is slightly smaller than I1. This signal Sb
Is differentiated by the differentiating circuit 14 to be a signal Sc, which is output to the subtracting circuit 15. As shown in FIG. 3 (d), this signal Sc has a peak of level I2 and is attenuated with the passage of time. Next, the subtraction circuit 15 subtracts the signal Sc from the speed command signal Sa, and the subtraction result is the corrected speed command signal Sa.
It is output from output terminal T3 as Sa1. This signal Sa1 is
As shown in FIG. 3 (e), at the drive start point t1, the level is smaller than the level of the speed command signal Sa by I2, and gradually increases with the change of the signal Sc with the passage of time.

Next, the speed feedback signal Sf is subtracted from the corrected speed command signal Sa1 by the subtraction circuit 5 shown in FIG. 1 to generate the signal Sd. The signal Sd has a level of (I1-I2) at the drive start point t1. Then, when the electric power corresponding to this level is applied from the electric power converter 2 to the linear motor primary side 3, the transported object 4 (FIG. 5) obtains thrust and the actual measurement degree starts to increase. Then, the level of the speed feedback signal Sf also starts to increase. Thereafter, the level of the corrected speed / speed command signal Sa1 continues to increase, and along with this, the level of Sf of the speed feedback signal also increases (see FIG. 3 (b)). On the other hand, the signal Sd once increases and then decreases, as shown in FIG. When the speed of the transported object 4 reaches the speed corresponding to the speed command signal Sa, the signal Sd
Level becomes 0.

Thus, in the above embodiment, the speed command signal Sa
Is not applied to the subtraction circuit 5 as it is, but the signal Sa
As shown in FIG. 3 (e), the signal is converted into a signal Sa1 whose initial level is small and whose level then gradually increases, and is applied to the subtraction circuit 5. As a result, unlike the conventional one, the deviation signal Sd having a large level is not suddenly applied to the power conversion device 2, so that the transported object 4 is not accelerated rapidly, and the inside of the transported object 4 is not accelerated. There is no danger of damaging the article.

In the above embodiment, the amplifier 10 (Sa
-Sf), but this amplifier 10
Alternatively, a unity gain amplifier may be used. In this case, I ₁ = I ₂ , and the initial value level of the signal Sd is always 0. Further, although the amplifier circuit by the amplifier 10 is configured to perform the proportional control, the present invention is not limited to this, and it may be configured to perform the proportional-integral control or may be configured by another application circuit.
Further, although the acceleration of the transported object is mainly described in the embodiment, the same operation is performed even when the deceleration is applied.

As described above, according to the present invention, every time the conveyed object reaches the primary side of the linear motor, the speed command signal is reduced by the speed command correction circuit according to the speed signal.
Corrected to increase gradually.

As a result, when the transported object is decelerated between the primary side of the linear motor and becomes too slow with respect to the speed command signal before correction, the transported object is not abruptly generated with a large thrust force. The speed control of the object is performed.

Therefore, it is possible to prevent the articles in the transported object from being damaged.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a linear motor conveying device according to an embodiment of the present invention, FIG. 2 is a circuit diagram of a speed command correction circuit in the same embodiment, and FIG. 3 is a change of each signal in the same embodiment. FIG. 4 is a block diagram showing the configuration of a conventional linear motor conveyance device, and FIG. 5 is a diagram showing changes in each signal in FIG. 2 ... Power control device, 3 ... Linear motor, 4 ... Transported object, 5 ... Subtraction circuit, 7, 9, 11 ... Resistor, 8 ... Inverter, 10 ... Amplifier, 12 ... Resistor, 13 ... Capacitor, 14 ... Differentiation circuit, 15 ... Subtraction circuit, Sa ... Speed command signal, Sf ... Speed feedback signal, Sb, Sc, Sd ...
Signal, Sa1 ... Corrected speed command signal

Claims (1)

[Claims] 1. A plurality of linear motor primary sides arranged at a predetermined interval in a transport path, and an object to be transported traveling on the transport path, each driven by the plurality of linear motor primary sides. A linear motor secondary side conductor, and a speed detecting means for detecting a traveling speed of the transported object and outputting it as a speed signal, each time the transported object passes through each of the linear motor primary sides, In a linear motor conveyance device for controlling the electric power supplied to each of the primary sides of the linear motors so that the speed command signal supplied from the outside and the speed signal coincide with each other, and causing the conveyed object to travel, When the conveyed object reaches each of the primary side of the linear motor, the speed command signal is reduced according to the speed signal, and then gradually increased to return to the original value. Linear motor transport device to.