JPH0114122B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for detecting abnormal rotation (so-called locked state, etc.) of a rotating rack, which includes a large number of endlessly connected trays that move on a circulation path.

Generally, in this type of rotating rack, if the tray becomes unable to drive for some reason and stops abnormally while the drive motor is energized, a The system was configured to detect abnormal rotation using a thermal relay for overload detection, cut off power to the motor, and display an abnormal stop if necessary. However, although this thermal relay is effective for abnormal stoppages such as when an overload is applied to the motor, it is effective when the chain used as a transmission means from the motor to the tray drive chain or the tray is connected in an endless manner. Not only does it not work on abnormal stoppages caused by broken chains, etc., but if a variable speed motor is used, the rotation speed will drop due to a failure in the control means or a drop in voltage, causing the tray to move. Even if the speed drops abnormally, it is impossible to detect this situation and make an emergency stop.

In view of the above-mentioned problems, the present invention makes it possible to reliably detect an abnormal rotation state when the moving speed of the tray decreases below a certain level while the tray drive motor is energized, regardless of the cause. A rotation abnormality detection device is provided.

Hereinafter, one embodiment of the present invention will be described based on the attached illustrative drawings. In FIG. 1, 1 is a drive gear 2.
4 is a tray attached to the endless chain 1 at regular intervals; These are interlocking tray drive motors. As shown in FIGS. 2 and 3, each tray 4 includes a detection plate 7, a supporting guide roller 8, a supporting guide rail 9, a steady rest guide roller 10, and a steady rest guide rail 1.
1, it is supported so as to be able to circulate in a fixed posture on a horizontal circulation path. PHS-F,
The PHS-R is a pair of photoelectric switches for detecting the detection target plate 7, and is attached to a fixed location beside the tray movement path at a distance such that both ends of the detection target plate 7 can be detected simultaneously.

Incidentally, among the series of trays 4, the origin tray 4a which is tray No. 1 is attached with an origin detection plate 7a, and an origin detection photoelectric switch PHS- detects only this origin detection plate 7a. X is arranged between the pair of photoelectric switches PHS-F and PHS-R.

Next, the structure and operation of the entire control device will be explained based on FIG. ,PHS
Using the detection signal from -R, an addition/subtraction counter function that adds up during normal rotation and subtracts during reverse rotation outputs a unique tray number for each tray passing through the cargo handling position. In addition, the photoelectric switch PHS-
The X detection signal uses the counter value as the origin (No. 1)
used to restore. Reference numeral 13 denotes a comparison circuit, which receives the call tray number input thereto and the detection tray number inputted from the tray number detection means 12.
When the next tray in the tray movement direction passes the called tray, deceleration command A is output, and a match occurs when the called tray number and the detected tray number match. Outputs signal C.

Reference numeral 14 indicates an OR gate element, and reference numeral 15 indicates an AND gate element. Due to the functions of these two gate elements, when the deceleration command A is being output, either the photoelectric switch PHS-F or PHS-R is activated. When the detection signal is output, a stop command B is output. 1
Reference numeral 6 denotes a stop position check circuit, which outputs a coincidence signal C after a certain period of time (a time set slightly longer than the expected time required for stopping) after the stop command B is output and checks both the photoelectric switches. If a detection signal is output from either PHS-F or PHS-R, a stop completion signal D is output, which is used as a start signal for the automatic load transfer device at the load handling position, etc. A stop position correction command E for inching the drive device 17 including the tray drive motor 5 so that the tray drive motor 5 is in the stopped state.
is output.

Reference numeral 18 is a timer that can set an arbitrary time, and here, when the tray 4 is being driven at a normal speed, the photoelectric switch PHS-F
(i.e., the time required for tray 4 to move one tray pitch)
The time is set to be slightly longer than that, and the clock operates only when there is an energization state detection signal F to the motor 5, and is reset to zero by receiving the detection signal from the photoelectric switch PHS-F as a reset signal G, and the time is reset to zero. When the time has elapsed, a rotational abnormality detection signal H is output as a motor power supply circuit OFF command.

Incidentally, when the tray 4 is being driven at a low speed by the deceleration command A, the time set in the timer 18 is set to be slightly longer than the time required for the tray 4 to move one tray pitch during this low speed movement. can be switched automatically. To switch the set time, the deceleration command A can be used as a set time switching command.

According to the above configuration, in order to call the tray 4 of the selected specific number to the handling position, the drive device 17 is operated with the call tray number set and the series of trays 4 are circulated and moved by the motor 5. , the numbers of the trays 4 passing through the cargo handling position are sequentially output from the detection means 12, and the detected tray numbers and the called trays are
No. is compared in the comparison circuit 13, and when the tray 4 one place before the loaded tray passes the cargo handling position, a deceleration command A is output, and the drive device 17 receives this deceleration command and rotates the motor 5. The speed will be automatically reduced to a predetermined low speed. After the series of trays 4 are moved at low speed in this way, the photoelectric switch PHS-F (when the tray is moving forward) or PHS
-R (during backward movement of the tray) detects the detected plate 7 of the tray 4, a stop command B is output, and upon receiving the stop command B, the drive device 17 stops driving the tray by the motor 5, and the drive device 17 stops driving the tray by the motor 5. 5 to the dynamic braking state. Therefore, the series of trays 4 will move a certain distance due to inertia and then stop. As a result, the call tray 4 is placed at the cargo handling position.
A pair of photoelectric switches are connected to both ends of one detection plate 7.
Status detected by PHS-F, PHS-R, e.g. ±
This means that it stops accurately within a 10mm range.

As described above, when the tray 4 is driven by the motor 5, that is, when the motor 5 is in the energized state, the motor energized state detection signal F
The timer 18 is activated by this, but when the tray 4 is moving at a normal speed, the detection signal from the photoelectric switch PHS-F is input to the timer 18 as a reset signal G before the set time elapses. Since the rotation is reset to zero, the abnormal rotation detection signal H is not output as the set time elapses.

However, if the moving speed of the tray 4 abnormally decreases for some reason even though the motor 5 is energized, or if the tray 4 becomes locked and stops abnormally, the reset signal G is activated. The set time has elapsed before being input to the timer 18,
A rotation abnormality detection signal H is output. The motor power supply circuit of the drive device 17 is activated by this detection signal H.
It is switched to OFF, and the power to the motor 5 is cut off. Of course, it is also possible to electrically indicate the emergency stop state due to abnormal rotation by means of an alarm, rotating light, or the like.

In the embodiment, a photoelectric switch PHS-F, which is one of the detection switches for detecting the tray number, and a tray are used as means for outputting a detection signal at time intervals proportional to the moving speed of the tray as the tray moves. 4
Although the detection target plate 7 provided at Further, this means is not limited to the method of detecting the detected portion provided on the tray 4, but may also detect a detected portion provided on a rotating member that rotates in conjunction with the tray 4. I can do it.

Furthermore, although the embodiments use individual control means or circuits, it is actually possible to use a computer in conjunction with the program control method. FIG. 5 is a flowchart showing the flow of program control when implementing the present invention using a computer.

The rotation abnormality detection device of the present invention can be implemented as described above, and its feature is that in a rotating rack equipped with a large number of trays that are connected in an endless manner and move on a circulation path, each tray is A detected part (detected plate 7 in the embodiment) is provided, and a detector (photoelectric switches PHS-F and PHS-R in the embodiment) for detecting the detected part is provided at a fixed position in the circulation path. A deceleration command and a stop command are given to the tray rotation drive device by comparing the count value of the detection signal from this detector with a set value, and a timer is provided which is reset to zero by the detection signal from the detector, and the timer is A first set time corresponding to the tray speed before the deceleration command is issued and a second set time corresponding to the tray speed after the deceleration command is issued are set, and each The present invention is configured to output a rotation abnormality detection signal that stops the rotation of the tray when a set time has elapsed.

According to the device of the present invention, it is possible to detect abnormal tray stops that cannot be detected with conventional thermal relays, or cases where the rotation speed of the motor itself abnormally decreases due to a failure in the rotation speed control system or a drop in voltage. Regardless of the cause, it is possible to detect an abnormal decrease in the speed of the tray and automatically stop the rotation of the tray. Furthermore, whether the tray is running at a steady speed or is running at a low speed after a deceleration command has been issued, it is possible to reliably detect that the speed has decreased from the normal speed at that time. You can.

Furthermore, according to the configuration of the present invention, the detected portion of each tray and the detector for detecting the detected portion necessary for controlling the target tray to decelerate at a certain distance before the calling position and stop at the calling position. As it is possible to use it as is and combine it with a timer that can freely set the time, it is not only possible to configure the device easily and inexpensively, but also to calculate the actual time required for the tray to travel one pitch. Measure and based on this measurement result,
You can determine the first and second set times to be set on the timer, and there is no need to convert the actual time to the number of pulses, which is required when using a pulse encoder, making it extremely simple and easy. It can be implemented.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view explaining the configuration of the rotary rack, Fig. 2 is a plan view showing the relationship between the tray and the detection switch, Fig. 3 is a side view of the same, and Fig. 4 is an illustration of an embodiment of the present invention. FIG. 5 is a flowchart showing the flow of control when executed under program control by a computer. DESCRIPTION OF SYMBOLS 1...Endless chain, 2...Drive gear, 3...Idle gear, 4...Tray, 5...Tray drive motor, 7, 7a...Detected plate (detected part), 12
... Tray No. detection means, 13 ... Comparison circuit, 16
... Stop position check circuit, 17 ... Tray drive device, 18 ... Timer, PHS-F, PHS-R,
PHS-X...Photoelectric switch (detection switch), A
... Deceleration command, B ... Stop command, F ... Motor energization state detection signal, G ... Timer reset signal, H ... Rotation abnormality detection signal.

Claims (1)

[Claims] 1. In a rotating rack equipped with a large number of trays that are connected in an endless manner and move on a circulation path, a detection part is provided in each tray and the detection part is detected at a fixed position in the circulation path. Arrange the vessels,
A deceleration command and a stop command are given to the tray rotation drive device by comparing the count value of the detection signal from this detector with a set value, and a timer is provided which is reset to zero by the detection signal from the detector. The first set time corresponding to the tray speed before the deceleration command is issued and the second set time corresponding to the tray speed after the deceleration command is issued are set, and each setting A rotational abnormality detection device for a rotating rack configured to output a rotational abnormality detection signal for stopping the rotation of the tray when a time has elapsed.