JPH0335215B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a conveyance device for conveying articles in a factory or the like, and in particular, the present invention relates to a conveyance device for conveying articles in a factory or the like, and in particular, a conveyance cart that moves with almost no frictional braking is moved to a predetermined position on a conveyance path. The present invention relates to a positioning and stopping device that can be stopped at a position in a short time.

[Prior Art] In this type of conveyance device, in order to load/unload or process objects to be conveyed, there are cases where it is necessary to accurately position and stop the conveyance cart at a station provided on the conveyance path.

FIG. 7 is a longitudinal sectional view showing an example of such a positioning and stopping device. In this figure, a secondary iron core 2 is fixed to the lower surface of a transport vehicle 1.
On the other hand, on the conveyance path 3 side, a primary iron core 4 is arranged opposite to this secondary iron core 2 . Then, when the carrier 1 comes to the stop position, the coil 5 wound around the primary iron core 4 is energized to cause the primary iron core 4 to attract the secondary iron core 2.
The carriage 1 can be stopped at a predetermined position.

FIG. 8 is a graph showing the relationship between the displacement x of the transport vehicle 1 from the stop position and the restoring force f during the above-mentioned stop. As can be seen from this figure, when the displacement x is positive, a negative restoring force f acts, and the displacement x
When is negative, a positive restoring force f acts. Therefore, the transport vehicle 1 vibrates around the displacement x = 0 (equilibrium point), and ultimately comes to a stop at this equilibrium point while being affected by frictional force, air resistance, eddy current resistance, etc. .

This type of positioning and stopping device can apply braking force to a moving object and stop it without contact.
Compared to those that use mechanical friction, there is no risk of dust generation and there are advantages in that maintenance is easier. Therefore, if such a positioning and stopping device can be incorporated into a magnetically levitated conveyance device or the like driven by a linear induction motor,
It is possible to realize a transport device that can support, drive, and brake the transport vehicle in a non-contact manner, and is extremely convenient for use in clean rooms where generation of dust is extremely disliked.

[Problems to be Solved by the Invention] However, when the above-mentioned non-contact stopping device is incorporated into a magnetic levitation type or air levitation type conveyance device, the following inconveniences occur.
Incorporation into this type of transport device has not been realized.

In other words, when the transport vehicle is supported by wheels, etc., an appropriate frictional force exists between the transport vehicle and the transport path, so when the above-mentioned positioning and stopping device is incorporated, this frictional force acts as a vibration damping force. , the transport vehicle can be stopped in a relatively short time. However, when it is incorporated into a magnetic levitation type conveyance device or the like, it takes a long time to stop because there is no mechanical friction between it and the conveyance path.

The present invention was made against this background, and an object of the present invention is to provide a positioning and stopping device that can be incorporated into a magnetic levitation type or air levitation type conveyance device and can stop a conveyance truck within a short time. purpose.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a positioning and stopping device for stopping a conveyance cart moving along a conveyance path at a predetermined stop position.
It consists of a primary side and a secondary side configured in a non-contact manner, one of which is attached to the stop position side and the other to the conveyance cart side, and the attachment interval in the conveyance direction on the stop position side and the A plurality of electromagnets with different installation intervals in the transport direction on the transport vehicle side,
a detection means for detecting the vibration speed near the stop position of the conveyance vehicle; and a voltage or current proportional to the vibration speed superimposed on a constant voltage or constant current and supplied to the primary side of at least one of the electromagnets, and damping the vibration speed. and a control means for generating force.

[Function] According to the above configuration, when the vibration speed of the transport vehicle is positive, a restoring force in a negative direction is applied, and when the vibration speed is negative, a restoring force in a positive direction is applied, and the displacement and restoring force of the transport vehicle are controlled. The carriage can be quickly stopped while creating a hysteresis loop as shown in FIG. Further, by adjusting the constant voltage (or constant current) supplied to the plurality of electromagnets, it is possible to finely adjust the stopping position.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 and FIG. 2 are diagrams showing the configuration of an embodiment of the present invention. In these figures, 11
1 is a transport vehicle, and 12 is near the stop position. Near this stop position 12, primary side cores 13a and 14a of a pair of electromagnets 13 and 14 are arranged at a distance of l1 in the conveyance direction. The primary iron core 13
a, 14a has a substantially U-shaped cross section, is arranged with the opening facing upward, and has an excitation coil 13 at the bottom.
b, 14b are wound.

On the other hand, an electromagnet 13,
14 secondary side cores 13c and 14c are
They are installed at a distance of l2 (≠l1).
The secondary iron cores 13c, 14c have a rectangular parallelepiped shape, and when the carrier 11 moves, the primary iron cores 13a, 1
It is adapted to be able to move through the opening at 4a.

The coils 13b and 14b are connected to the output end of the control device 15. This control device 15 uses the speed signal output from the speed detector 16 to
The voltages supplied to the coils 13b and 14b are controlled separately.

Here, the speed detector 16 consists of a long slit plate attached to the side of the transport vehicle, a pair of photosensors provided on the ground side sandwiching this slit plate, and the speed based on the output of the photosensor. A determiner that determines the direction (speed sign) and an F/V that converts the output of the photosensor into an analog signal (speed signal)
A large number of vertical slits in two series with different phases are cut in the horizontal direction on the slit plate, and these are independently detected by the pair of photosensors.

On the other hand, the control device 15 has a chopper function,
The DC voltage supplied from the power source 17 is controlled by the speed signal and speed code. That is, the control device 15 includes an adder that adds the speed signal to a constant voltage according to its sign, a triangular wave generator, and a comparator that compares the triangular wave output from the triangular wave generator with the output of the adder. and an FET that turns on/off the DC voltage supplied from the power supply 17 using the output of this comparator as a gate signal.

Next, the operation of this embodiment will be explained with reference to FIGS. 3 to 6.

First, to help understanding, electromagnets 13 and 14
The state when the same constant voltage is applied to the third
This will be explained with reference to the figures.

FIG. 3 shows the relationship between displacement x and restoring force f when the transport vehicle 11 is displaced from the stop position. In this figure, displacement x=0 means the second
This is the position shown in the figure. That is, the primary iron core 13
The intermediate point between a and 14a and the secondary cores 13c and 14
The midpoint of c is the matching position. When the displacement x=0, the primary core 13a of the electromagnet 13 attracts the secondary core 13c to the left in FIG. 2, that is, in the negative direction. Further, the primary core 14a of the electromagnet 14 attracts the secondary core 14c to the right in FIG. 2, that is, in the positive direction. In this case, the positive and negative suction forces (restoring forces) become equal, and the restoring force f applied to the transport vehicle 11 becomes zero.

When the transport vehicle 11 is displaced in the positive direction from this position, the displacement x becomes positive, the restoring force in the negative direction by the electromagnet 13 gradually increases, and the restoring force in the positive direction by the electromagnet 14 gradually weakens. As a result, a composite restoring force f (<0) as shown by the broken line in FIG. 3 acts on the carrier 11, and the carrier 11 is pulled in the negative direction. Conversely, when the transport vehicle 11 is displaced from the position of displacement x=0 in the negative direction, the attraction force of the electromagnet 13 becomes weaker and the attraction force of the electromagnet 14 becomes stronger. As a result, the carriage 11 is pulled in the forward direction. In other words, the carriage 11 vibrates around the displacement x=0.

Next, the operation of this embodiment will be explained with reference to FIG. FIG. 4 shows the displacement x and the restoring force when the voltage applied to the electromagnet 14 is kept constant while an excitation voltage that is a voltage proportional to the vibration speed of the transport vehicle 11 and a constant voltage is applied to the electromagnet 13. It is a graph showing the relationship with f. Note that this excitation voltage is
It is formed by the control device 15 as described above.

In FIG. 4, the elliptical solid line represents the electromagnet 13.
The elliptical broken line is the restoring force acting on the transport vehicle 11. Also, the arrows on each ellipse are
The speed direction of the transport vehicle 11 is shown. As can be seen from the figure, when the speed is positive (the arrow points to the right), the excitation voltage of the electromagnet 13 increases, its attractive force increases, and the carriage 11 is pulled in the negative direction. On the other hand, when the speed is negative, the excitation voltage of the electromagnet 13 decreases, its attractive force decreases, and a strong force in the positive direction acts on the carrier vehicle 11. That is, the transport vehicle 11 has
A force in the direction opposite to the moving direction acts, and the vibrations are gradually attenuated, and the excitation voltage is also gradually reduced accordingly. Therefore, the restoring force f converges to zero while drawing an elliptical curve (hysteresis loop) that gradually decreases, and the transport vehicle 11 quickly stops. In addition,
In this case, energy corresponding to the area of the hysteresis loop is applied to the electromagnet 13 and the control device 15.
etc. It becomes a form that is consumed.

FIG. 5 shows the damping characteristics of the positioning and stopping device according to this embodiment installed on a magnetically levitated truck, and FIG.
Figure 4b shows the attenuation characteristic when a constant voltage is supplied to magnets 3 and 14, and when the electromagnet 13 is made to draw a hysteresis loop as shown in Figure 4. As can be seen from this figure, the latter decays much more quickly and converges to zero. In fact, when only a constant voltage was applied, it did not stop even after 6 seconds, but when a hysteresis loop was drawn, it was confirmed that it stopped after about 2 seconds.

FIG. 6 is a graph showing the stopping positions when the constant voltages supplied to the electromagnets 13 and 14 are varied. In this case, the excitation voltage of the electromagnet 14 is higher than the excitation voltage of the electromagnet 13. As a result, the overall restoring force f shifts to the right from the zero point, as shown by the broken line, and the transport vehicle 11 stops at point P in the figure. In this way, by controlling the excitation voltage applied to the electromagnets 13 and 14, fine adjustment of the stop position becomes possible. This is the primary side core 13a, 14
Installation interval l1 of a and secondary cores 13c, 14c
This is the effect of varying the installation interval l2, and l1
This effect cannot be obtained when = l2. This is because when l1=l2, it always stops at the displacement x=0.

In addition, in the above embodiment, the installation interval of each iron core is
Although l1 and l2 are set as l1>l2, this may be reversed.
Further, the primary side of the electromagnet may be attached to the transport vehicle 11 side. Furthermore, instead of controlling with a voltage proportional to the vibration speed, control may be performed with a current proportional to the vibration speed.

[Effects of the Invention] As explained above, in the present invention, the stopping electromagnet is excited by superimposing a voltage or current proportional to the vibration speed of the transport vehicle on a constant voltage or constant current, so that hysteresis is eliminated. You can gain the resilience to draw a loop. Thereby, the carrier can be quickly stopped.

Furthermore, by adjusting the constant voltage (current) supplied to the electromagnet, the stopping position can be freely finely adjusted. Thereby, the stop position at the time of initial setting and the stop position during operation can be freely finely adjusted.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the configuration of an embodiment of the present invention, Fig. 2 is a side view of the embodiment, and Fig. 3 shows the displacement and restoring force when a constant voltage is applied to the electromagnets 13 and 14. A graph showing the relationship between
Figure 5 is a graph showing the relationship between displacement and restoring force when the motor is excited, comparing the attenuation characteristics when stop control is performed with only a constant voltage and the damping characteristics when stop control is performed while drawing a hysteresis loop. The graph shown in FIG. 6 is a graph showing the state when the stopping position is finely adjusted by changing the constant voltage applied to the electromagnets 13 and 14, and FIG. 7 shows the configuration of the main parts of a conventional positioning and stopping device. The longitudinal sectional view shown in FIG. 8 is a graph showing the relationship between displacement and restoring force in a conventional positioning and stopping device. 11... Transport vehicle, 12... Near stop position, 1
3, 14...Electromagnet, 13a, 14a...Primary side iron core, 13b, 14b...Coil, 13c, 14
c... Secondary iron core, 16... Speed detector, 17...
…Control device.

Claims (1)

[Scope of Claims] 1. A positioning stop device that stops a conveyance cart moving along a conveyance path at a predetermined stop position, which comprises a primary side and a secondary side configured in a non-contact manner, either of which a plurality of electromagnets, one of which is attached to the stop position side and the other to the conveyance vehicle side, and the attachment intervals in the conveyance direction on the stop position side are different from the attachment intervals in the conveyance direction on the conveyance vehicle side; detecting means for detecting the vibration speed near the stop position of the electromagnet; and a voltage or current proportional to the vibration speed superimposed on a constant voltage or constant current and supplied to the primary side of at least one of the electromagnets to generate a damping force. A positioning and stopping device characterized by comprising: control means for controlling the positioning and stopping device. 2. The positioning and stopping device according to claim 1, wherein the stopping position of the transport vehicle is finely adjusted by adjusting the constant voltage or constant current. 3. The positioning and stopping device according to claim 1, characterized in that instead of generating the magnetic field by supplying the constant voltage or constant current, a magnetic field generated by a permanent magnet is used.