JPH0132126B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a speed control method for a self-propelled shiftable conveyor capable of fan-shaped rotation.

``Conventional technology'' In order to perform operations such as land reclamation with earth and sand and extraction of earth and sand continuously, it is necessary to move the conveyor as the work progresses.

FIG. 5 is a plan view showing the configuration of a self-propelled shiftable conveyor for performing this type of civil engineering work. In this figure, 1 is a belt stretched over the entire length, 2-i (i = 1, 2,...n) is a group of individual frames that divide the entire length into fixed lengths, and 1 is a set of frames. The frame group 2-i is composed of several frames connected in series. Further, each frame group 2-i is connected in series by a connecting member (not shown). 3-i is each frame group 2-i
This is a crawler (traveling device) that is attached to the lower part of the frame group 2-i and causes each frame group 2-i to travel laterally.
The crawler 3-i is driven by a variable speed electric motor (not shown), and causes the conveyor to move laterally or to rotate in a fan shape as shown in the figure. This turning operation is performed in a fan shape by centering on one end A of the conveyor and changing the speed of the crawler 3-i according to the distance from the turning center A to the other end. That is, if the distance (total length) from the turning center A of the conveyor to the other end is L, the turning speed at this other end is V, and the distance from the turning center to the crawler 3-i is li, then the speed of the crawler 3-i is vi is vi=(li/L)・V...(1). This causes the conveyor to rotate in a straight line.

"Problems to be Solved by the Invention" By the way, in the conveyor described above, if the total length L is 500 m and the length of one frame group 2-i is 10 m, then the number n of frame groups 2-i is 50. , the speed v ₁ of the crawler 2-1 closest to the turning center A, and the crawler 2-50 furthest from the turning center A.
The ratio of this to the speed v ₅₀ is also v ₁ :v ₅₀ =1:50...(2). Therefore, the speed ratio of the variable speed electric motor that drives the crawler 3-i must also satisfy the above equation (2). However, there is currently no speed control device that satisfies the above conditions and is inexpensive.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a speed control method for a self-propelled shiftable conveyor that can smoothly turn a long conveyor with an overall length L of several hundred meters. The purpose is

"Means for Solving the Problems" The present invention includes an induction motor provided in a traveling device as a drive source, and an inverter device that supplies alternating current of variable frequency to the induction motor, and provides a driving device that operates at a predetermined distance from the turning center. While continuously giving a speed command proportional to the distance from the turning center to the inverter device corresponding to the traveling device located outside (see equation (1) above), The present invention is characterized in that a stop command and a speed command are alternately given to the corresponding inverter device at a time distribution corresponding to the distance from the turning center.

"Operation" According to the above method, the traveling device located outside the predetermined distance from the turning center, that is, the traveling device traveling at a speed that can be controlled by the inverter device,
A traveling device that continuously moves at a speed proportional to the distance from the turning center and is within the predetermined distance, that is, a traveling device that travels at a speed outside the speed control range of the inverter device, has a distance from the turning center. Because the conveyor moves and stops alternately at time intervals corresponding to This makes it possible to rotate it in a shape.

"Embodiment" Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the electrical configuration of one embodiment of the present invention. In this figure, 5-
i (i=1, 2,...50) is an induction motor that drives each crawler 3-i (i=1, 2,...50) shown in FIG. 2, and 6-i is an induction motor 5-i with a variable frequency. 7 is a speed control device that supplies a speed command Ui to the inverter device 6-i. Here, an inverter device 6-i capable of controlling the speed of the crawler 3-i driven by the induction motor 5-i in the range of V ₀ to _{V 0} /20 is used, and the total length of the conveyor is 500 m, each Assuming that the length of the frame group 2-i is 10 m, as shown in Fig. 2, the crawler 3 has a speed command Ui of V ₀ /20 or less.
−1 (Ui=V ₀ /50) and crawler 3-2 (Ui=
2V _0/50 ), inverter device 6-1, 6
-2 speed control range. Therefore, in this embodiment, the speed commands U ₁ and U ₂ given to the inverter devices 6-1 and 6-2 are both values corresponding to the lowest speed within the speed control range, that is, V ₀ /20, and the third As shown in the figure, within a period of a certain repetition period T, the turning center A
The time t corresponding to the distance from the vehicle is given. As a result, the temporally averaged moving speed V of each crawler 3-1, 3-2 is as follows: V=(V ₀ /20)·(t/T) (3). Therefore, by appropriately setting the time t for applying the speed command value V ₀ /20 in accordance with the distance from the turning center A, each crawler 3-1, 3-2 can alternately repeat movement and stop. As a result, each crawler 3-1, 3-2 is moved at a low speed outside the speed control range of the inverter devices 6-1, 6-2, and at a speed V corresponding to the distance from the turning center A. As a result, the conveyor can be rotated in a substantially straight line.

Next, we will consider how to set the repetition period T and the crawler driving time t in the above equation (3). First, as shown in Fig. 4A, each frame group 2
On both sides of the frame 2-i, there are rails 9-i that interconnect several frames constituting each frame group 2-i.
However, let us consider the meandering limit determined by the shape of the rail 9-i when the conveyor meanderes with the crawler 3-2 leading in the direction indicated by the arrow. Note that the meandering between the frames connected by the rails 9-i is regulated by the rigidity of the rails 9-i. As shown in Figure 4B, rail 9-i
If the length of rail 9-i is D, the width of rail 9-i is d, and the gap between adjacent rails 9-i is Δd, this is a diagram when rail 9-2 is bent to bend relative to rail 9-3. The meandering limit value Xd1 shown in is as follows: Xd1=D・(Δd/d) (4). On the other hand, the meandering limit value is based on the constraint that belt 1 does not come off when the conveyor meanderes.
Assuming Xb1, the smaller of the meandering limit value Xd1 and Xb1 becomes the meandering limit value X1, so X1=min(Xd1, Xb1)...(5). Usually, Xb1 is smaller, length D = 10m
For rail 9-i, Xb1 is approximately 30 cm. Here, meandering (bending) occurs due to the speed difference between adjacent crawlers 3-i because the speed command V ₀ /
Crawler 3-i at a position corresponding to 20, and crawler 3-(i-
1). Because inverter device 6
The range in which speed can be controlled by -i is V ₀ to V ₀ /
20, the crawler 3-i corresponding to the speed command V ₀ /20 and the crawler 3 closer to the fulcrum
This is because there is no other choice but to move both -(i-1) at the lowest speed V ₀ /20. If this continues, the crawler 3-(i-1) closer to the fulcrum will naturally overtake the crawler 3-i, causing meandering.
Therefore, in order to prevent such meandering, the crawler 3 when moved at different angles from each other
Let the speed difference between -i and crawler 3-(i-1) be ΔVmax.

Let us now concretely consider the case shown in Figure 2. In this figure, the total length of the conveyor L = 500
m, the number of frame groups 2-i n = 50, the length of the rail D = 10 m, and the width of the rail d = 60 mm,
Rail gap Δd = 10 mm, speed V ₀ = 3 m/min,
If the meandering limit value X1 = 30cm, each crawler 3-
i is the speed controllable range of the inverter device 6-i
When moving continuously at V ₀ to V ₀ /20, the crawler 3-3 is given a speed command value of 3V ₀ /50 (>V ₀ /20), and the crawler 3-3, which is closer to the fulcrum and has an original speed A bend occurs between the crawler 3-2 to which the command value 2V ₀ /50 (<V ₀ /20) should be given (actually, the speed command value V ₀ /20 is given). here,
The speed difference ΔVmax for crawler 3-3 and crawler 3-2 to turn without meandering is as follows: ΔVmax = (3V ₀ /50) - (2V ₀ /50) = V ₀ /50 = 3/50... ( 6) becomes. And crawler 3-3 and crawler 3-
2 moves at the same speed (for example, speed command value 3V ₀ /50), after Ta seconds, ΔVmax・
Since a difference in movement of Ta occurs, the following must be satisfied: ∴Vmax・Ta≦X1 ∴Ta≦X1/∆Vmax (7). Multiply this by a safety factor of 1/2 to select the repetition period T (see Figure 3 and equation (4)). Therefore, from the above, T=X1/(2・ΔVmax)=0.3/(2・(3/50))=2.5min ……(8). From this, it is considered that T=3 min is appropriate. Repeating starting and stopping at intervals of this order can be performed without any problem in the induction motor 5-i of about 0.4 kW. Moreover, once the repetition period T is determined, crawler 3-1 and crawler 3
-2 driving time t can be easily obtained from equation (1).

According to the embodiment described above, the crawler 3-i that is outside the predetermined distance from the turning center A continuously moves at a speed proportional to the distance from the turning center A, and the crawler 3-i is within the predetermined distance. Crawler 3-i is
Since the conveyor repeats movement and stopping at time intervals corresponding to the distance from the turning center A, the conveyor can turn in a substantially straight line even when using a relatively inexpensive inverter device 6-i with a narrow speed control range. becomes possible.

"Effects of the Invention" As explained above, according to the present invention, a traveling device is provided with an induction motor provided as a drive source, and an inverter device that supplies variable frequency alternating current to the induction motor. A speed command proportional to the distance from the turning center is continuously given to an inverter device corresponding to a traveling device located outside the predetermined distance, while a speed command of a value proportional to the distance from the turning center is continuously given to an inverter device corresponding to a traveling device located within the predetermined distance. Because the system alternately gives stop commands and speed commands in a time distribution that corresponds to the distance from the turning center, it is possible to control a long aircraft (several hundred The conveyor can be rotated by a distance of 1.2 meters or more, and the cost of the entire device can therefore be reduced.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the electrical configuration of an embodiment of the present invention, Fig. 2 is a plan view showing the external structure of a self-propelled shiftable conveyor to which the embodiment is applied, and Fig. 3 is the same embodiment. A graph showing an example of the setting of the speed command Ui in FIG. 4 A and B are diagrams for explaining the operation of the same embodiment, and FIG. It is. 1...Belt, 2-i (i=1, 2,...)...
Frame group, 3-i...Crawler (traveling device),
5-i...Induction motor, 6-i...Inverter device, 7...Speed control device, Ui...Speed command, T
...Repetition period, t...Crawler driving time.

Claims (1)

[Claims] 1. A speed control method for a self-propelled shiftable conveyor in which frames having traveling devices are connected in cascade and can rotate around one end of the cascaded connection body as a turning center, including an induction motor provided as a drive source in the traveling device; , an inverter device that supplies variable frequency alternating current to the induction motor, and the inverter device corresponding to the traveling device located outside the predetermined distance from the turning center is provided with a speed command having a value proportional to the distance from the turning center. is continuously given, while a stop command and a speed command are given alternately to inverter devices corresponding to traveling devices within the predetermined distance at a time distribution corresponding to the distance from the turning center. Speed control method for running shiftable conveyor.