Belt meandering detection device for belt conveyors used in extremely low temperature environments

Abstract

To provide a meandering detection device of a belt applicable to a belt conveyer used in a cryogenic environment.SOLUTION: A meandering detection device 21 of a belt 7 of a belt conveyer used in a cryogenic environment comprises: a contact movable member movable following the meandering of the belt 7 coming into contact with side end faces of the belt 7; an interlocking member interlocking with the movement of the contact movable member; a first optical sensor 33 detecting movement of the interlocking member; and determination means for determining whether or not the side end faces of the belt 7 meander exceeding a reference range, by input from the first optical sensor 33.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a belt meandering detection device that is particularly applicable to a belt conveyor used in an extremely low temperature environment. [Background technology]

[0002] Conventionally, belt conveyors are used to transport goods in the food industry and the like. In general, the endless belt of a belt conveyor (hereinafter simply referred to as "belt") is supported by a pair of rolls, and the belt runs when one of the rolls (the driving roll) is driven to rotate. During the running of this belt, the belt may move in the axial direction of the rolls, which is called meandering. The meandering of the belt not only hinders accurate work, but also poses the risk of damage to the side edges of the belt if the meandering becomes too wide. Therefore, when meandering occurs, it is necessary to accurately detect it and take appropriate action.

[0003] Methods for detecting belt meandering are disclosed in Patent Documents 1 and 2. The "belt meandering control device" disclosed in Patent Document 1 is equipped with a rotary encoder for detecting the rotation angle of the drive roll or driven roll, a line sensor for detecting the position of the belt edge line, and a reflective sensor for reading the belt's rotation marks, and detects the belt position based on the data from these devices to control the belt meandering.

[0004] In addition, in the "belt meandering prevention device" disclosed in Patent Document 2, the belt is positioned between a light-emitting element and a light-receiving element (see FIG. 2 in Patent Document 2), and whether the belt is within a reference range is detected based on whether the belt blocks the light (two reference lines) from the light-emitting element to the light-receiving element. When the belt exceeds the reference range, the driving roller or the driven roller, or both rollers, are tilted forward and backward with respect to the traveling direction plane, thereby controlling the meandering of the belt. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6074095 [Patent Document 2] JP 2008-195463 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned conventional technology, an optical sensor consisting of a light emitting element and a light receiving element is used to detect the meandering state of the belt. For example, belt conveyors used for transporting, drying, cooling, freezing, etc. in the food industry may be used at temperatures below -50°C. In such extremely low temperature environments, moisture in the air condenses into water or ice, which can adhere to optical sensors. If condensation water or ice adheres to the optical sensor, it blocks the light transmitted from the light emitting element to the light receiving element, making it impossible to accurately detect the position of the belt.

[0007] Furthermore, optical sensors are electronic devices and may not be usable in extremely low temperature environments or environments where condensation occurs, as described above. The above-mentioned conventional technology is designed for use in a general temperature range, and has the problem that it cannot be used in an extremely low temperature environment.

[0008] The present invention has been made to solve the above problems, and has an object to provide a belt meandering detection device that can be applied to belt conveyors used in extremely low temperature environments. [Means for solving the problem]

[0009] (1) The belt meandering detection device of the present invention is a belt meandering detection device for a belt conveyor used in an extremely low temperature environment, and is characterized in that it comprises a contact movable member that contacts the side end surface of the belt and moves in accordance with the meandering of the belt, an interlocking member that interlocks with the movement of the contact movable member, a first optical sensor that detects the movement of the interlocking member, and a determination means that determines whether the side end surface of the belt is meandering beyond a reference range based on an input from the first optical sensor.

[0010] (2) Also, in the above-mentioned (1), the first optical sensor comprises a plurality of light-emitting elements and a plurality of light-receiving elements, the light-emitting elements and the light-receiving elements being arranged on either side of the interlocking member, which is a plate-shaped interlocking plate, and the determining means determines whether the belt is meandering or not, and if so, in which direction it is meandering (to the left or right), based on a combination of whether the light-emitting elements receive the light of the light-emitting elements or not.

[0011] (3) Furthermore, in the device described in (1) or (2) above, a second optical sensor is further provided which detects when the side end surface of the belt has entered a required stop range that is significantly beyond the reference range due to movement of the interlocking member, and the determination means determines whether or not the side end surface of the belt has entered the required stop range based on an input from the second optical sensor.

[0012] (4) Furthermore, in any one of the above (1) to (3), a shielding wall is provided along the side end surface of the belt to block cold air, and the first optical sensor is disposed on the back side of the shielding wall.

[0013] (5) Furthermore, in any of the above (1) to (4), the present invention is characterized in that it comprises a shielding floor provided above the side end surface of the belt to shield against cold air, an insertion hole formed in the shielding floor through which the shaft, which is the contact movable member, is inserted in a tiltable state, and a cover member having a through hole through which the shaft can pass and movably positioned on the shielding floor to cover the insertion hole, and the shaft passes through the through hole and the insertion hole to extend below the shielding floor and contact the side end surface of the belt. Effect of the Invention

[0014] In the present invention, there are provided a contact movable member that contacts the side end surface of the belt and moves in accordance with the meandering of the belt, an interlocking member that interlocks with the movement of the contact movable member, a first optical sensor that detects the movement of the interlocking member, and a determination means that determines whether the side end surface of the belt is meandering beyond a reference range based on the input from the first optical sensor.Since this allows the occurrence of meandering to be detected without directly detecting the position of the belt with an optical sensor, the present invention can be applied to belt conveyors used in extremely low temperature environments. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is an explanatory diagram of a belt meandering detection device according to a first embodiment of the present invention. [Diagram 2] 1 is a perspective view of a belt conveyor to which a belt meandering detection device according to a first embodiment of the present invention is applied. [Diagram 3] 3 is a view of the belt conveyor shown in FIG. 2 taken along the line AA. [Figure 4] FIG. 4 is an enlarged view of part B in FIG. [Diagram 5] 3 is an explanatory diagram of a cover member of the belt meandering detection device according to the first embodiment of the present invention. FIG. [Figure 6] 3 is an explanatory diagram of a first optical sensor of the belt meandering detection device according to the first embodiment of the present invention. FIG. [Figure 7] FIG. 3 is an explanatory diagram illustrating the operation of the belt meandering detection device according to the first embodiment of the present invention. [Figure 8] 5 is a diagram showing another aspect of the belt meandering detection device according to the first embodiment of the present invention. FIG. [Figure 9] 10 is an explanatory diagram (part 1) illustrating the operation of a belt meandering detection device according to a second embodiment of the present invention. FIG. [Figure 10] FIG. 11 is an explanatory diagram (part 2) illustrating the operation of the belt meandering detection device according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [Embodiment 1] A belt meandering detection device according to a first embodiment of the present invention (hereinafter simply referred to as a "meandering detection device") detects meandering of a belt of a belt conveyor used in an extremely low temperature environment. Prior to describing the belt meandering detection device, an example of a belt conveyor to which the belt meandering detection device of the present embodiment is applied will first be described with reference to Figs. 2 to 4. FIG. 2 is a perspective view of the belt conveyor, FIG. 3 is a view taken along the line AA in FIG. 2, and FIG. 4 is an enlarged view of a portion B in FIG.

[0017] The belt conveyor 1 in this embodiment is used to transport, dry, cool, freeze, etc., objects such as food, and as shown in FIG. 2, has a belt 7 stretched between a driving roll 3 and a driven roll 5, and a cold air supply tunnel 9 that cools objects such as food with cold air generated by a low-temperature liquefied gas such as liquid nitrogen.

[0018] A motor (not shown) for driving and rotating the drive roll 3 is connected to one end of the roll shaft of the drive roll 3. Further, a meandering control air cylinder 11 for controlling the meandering of the belt 7 by horizontally tilting the driven roll 5 is connected to both ends of the roll shaft of the driven roll 5 .

[0019] The inside of the cold air supply tunnel 9 is supplied with cold air by a liquid nitrogen supply nozzle (not shown) and a fan 13 provided in the cold air supply tunnel 9, and is kept in a cryogenic environment of, for example, about -100°C or less. As described above, since the belt conveyor 1 in this embodiment is used in an extremely low temperature environment, it is preferable to use a steel belt for the belt 7, which is resistant to an extremely low temperature environment.

[0020] Above the belt 7, U-shaped shielding members 15 for shielding cold air on the line are provided on both sides along the side end faces of the belt 7. Hereinafter, in this shielding member 15, the part perpendicular to the belt 7 will be referred to as the shielding wall 17, and the part horizontal to the belt 7 and closer to the belt 7 will be referred to as the shielding floor 19.

[0021] When cooling food using the above-mentioned belt conveyor 1, a motor connected to the drive roll 3 rotates and drives the drive roll 3 to run the belt 7 in the direction of the arrow in Figure 2, transporting the food placed on the belt 7 and passing it through the cold air supply tunnel 9 to cool it.

[0022] As shown in Figures 3 and 4, the meandering detection device 21 in this embodiment is provided upstream in the belt running direction, i.e., on the back side (opposite the belt) of the shielding wall 17 in the vicinity of the driven roll 5. Two fixed plates 23 (only the front one is shown in Figure 4) are provided in the shielding member 15 in the depth direction of the page so as to sandwich the meandering detection device 21. A schematic view of the meandering detection device 21 through the fixed plate 23 is shown in Figure 1.

[0023] As shown in Figure 1, the meandering detection device 21 comprises a shaft 25 which is a contact movable member in the present invention, and a plate-shaped interlocking plate 27 which is an interlocking member in the present invention, and a cover member 31 which covers an insertion hole 29 formed in the shielding floor 19 through which the shaft 25 passes is movably arranged on the shielding floor 19. Also provided is a first optical sensor 33 that detects the movement of the interlocking plate 27, and a determination means 35 that determines whether or not the side end surface of the belt 7 meanders beyond a reference range based on an input from the first optical sensor 33. Each component will be described in detail below.

[0024] <Shaft> The shaft 25 is a rod-shaped member provided so as to tilt in accordance with the meandering of the belt 7. The lower side of the shaft 25 is inserted through a through hole 37 (see FIG. 5) formed in the cover member 15 and an insertion hole 29 formed in the shielding floor 19, and extends below the shielding floor 19, and the lower end side surface of the shaft 25 is in contact with the side end surface of the belt 7. In addition, an interlocking plate 27 is connected to the upper part of the cover member 31 in the shaft 25. The insertion hole 29 is an elongated hole that is long in the width direction of the belt 7 so that the shaft 25 can tilt (see FIG. 6. Note that FIG. 6 shows the cover member 31 in a see-through manner). The means for making the shaft 25 follow the meandering of the belt 7 will be described later. The material of the shaft 25 is preferably a metal that does not cause low-temperature brittleness (austenitic stainless steel, etc.).

[0025] The shaft 25 and the interlocking plate 27 may be connected via a connecting member 39 as shown in Fig. 4, or may be directly connected. However, since the shaft 25 in contact with the belt 7 is likely to become cold, it is preferable to connect the shaft 25 and the interlocking plate 27 via the connecting member 39, since this can prevent the cold from being transferred to the interlocking plate 27 and makes it difficult for condensation to form on the first optical sensor 33 installed near the interlocking plate 27. Note that the connecting member 39 is not shown in Fig. 1.

[0026] <Interlocking plate> As described above, interlocking plate 27 is connected to shaft 25 and moves in accordance with the movement of shaft 25, and is formed by cutting out a portion of a rectangular plate to form a generally L-shape. Interlocking plate 27 is attached to shaft member 41 provided between two fixed plates 23 so as to be able to swing in an L-shape that is laid down on its side. The material of the interlocking plate 27, like the shaft 25, is preferably a metal that does not cause low-temperature brittleness (austenitic stainless steel, etc.).

[0027] Moreover, one end of a spring 43, which is a means for making the shaft 25 follow the meandering of the belt 7, is attached to the interlocking plate 27, and the other end of the spring 43 is fixed to the shielding floor 19. In the state shown in FIG. 1 (where both ends of the belt 7 are within the standard range and no meandering occurs), the spring 43 is attached in a stretched state compared to the standard state, and the force of the spring 43 attempting to compress causes the interlocking plate 27 to rotate clockwise (in the direction of the arrow in the figure) around the shaft member 41 as the central axis.

[0028] When the interlocking plate 27 rotates clockwise, the shaft 25 connected to the interlocking plate 27 tilts, and the lower portion of the shaft 25 is pressed against the side end surface of the belt 7 . As a result, the lower portion of the shaft 25 is always pressed against the side end surface of the belt 7 with a biasing force that does not affect the meandering of the belt 7.

[0029] Therefore, for example, if the belt 7 in Figure 1 moves to the left in the figure due to meandering, the spring 43 will contract, causing the interlocking plate 27 to rotate clockwise, and the shaft 25 will tilt further while the lower part of the shaft 25 remains in contact with the side end surface of the belt 7. On the other hand, when the belt 7 meanders and moves to the right in the figure, the force of the belt 7 pushing the shaft 25 is greater than the biasing force of the spring 43, so the shaft 25 is pushed by the belt 7 and tilts in the opposite direction to the above. In conjunction with this, the interlocking plate 27 rotates counterclockwise and the spring 43 extends further. As described above, the shaft 25 tilts following the meandering of the belt 7, and the interlocking plate 27 rotates in conjunction with the movement of the shaft 25.

[0030] In FIG. 1, one end of spring 43 is fixed to interlocking plate 27 and the other end is fixed to shielding floor 19, but the other end may be fixed to another member, for example, fixed plate 23 or the like.

[0031] <Cover parts> The cover member 31 covers the insertion hole 29 formed in the shielding floor 19 to prevent cold air below the shielding floor 19 from entering upward through the insertion hole 29. As shown in Fig. 5(a), a through hole 37 through which the shaft 25 can pass is formed in the center of the cover member 31. In the installed state, as shown in Fig. 5(b), the cover member 31 is movably disposed on the shielding floor 19 with the shaft 25 passing through the through hole 37, and moves on the shielding floor 19 following the tilting of the shaft 25.

[0032] The cover member 31 covers the insertion hole 29, thereby preventing cold air from entering through the insertion hole 29 and causing condensation or the like on the first optical sensor 33.

[0033] <First optical sensor> The first optical sensor 33 is an optical sensor including a plurality of light-emitting elements 33a and light-receiving elements 33b, and in this embodiment, two of each are provided as shown in Fig. 6. The light-emitting elements 33a and the light-receiving elements 33b are disposed opposite each other on both sides of the interlocking plate 27, for example, by being fixed to the two fixed plates 23 described above.

[0034] When both side end surfaces of the belt 7 are within a reference range (see FIG. 1), as shown in FIG. 6, the upper of the two light-receiving elements 33b receives the light emitted by the light-emitting element 33a, while the lower light-receiving element 33b does not receive the light because the light from the light-emitting element 33a is blocked by the interlocking plate 27.

[0035] <Judgment means> The determination means 35 is electrically connected to the first optical sensor 33, and determines whether the belt 7 is meandering or not, and if so, in which direction (left or right) the belt is meandering, based on a combination of whether the light-emitting element 33a is received by the light-receiving element 33b or not.

[0036] When the determining means 35 determines that the belt 7 is meandering, the meandering control air cylinder 11 tilts the driven roll 5 horizontally to correct the meandering of the belt 7. A specific determination method in the determination means 35 and a method for controlling the meandering of the belt 7 will be described later in the operation description.

[0037] The operation of the meandering detection device 21 in this embodiment configured as above will be described with reference to Fig. 7. Note that in Fig. 7, the left-side shielding member 15, the fixed plate 23, and the determination means 35 are omitted from illustration. 7(a) shows a state in which both end faces of the belt 7 are within the reference range and no meandering occurs. When no meandering occurs, the upper light receiving element 33b receives light, but the lower light receiving element 33b does not receive light because the light is blocked by the interlocking plate 27. When the upper light receiving element 33b receives light but the lower light receiving element 33b does not receive light as described above, the determining means determines that "meandering is not occurring."

[0038] Fig. 7(b) shows a state in which belt 7 moves in the direction of the outline arrow and the left end face of belt 7 exceeds the reference range. When belt 7 moves to the left beyond the reference range as in Fig. 7(b), shaft 25 follows the movement of belt 7 and tilts clockwise because the lower part of shaft 25 is pressed against the side end face of belt 7.

[0039] When the shaft 25 tilts, the interlocking plate 27 connected to the shaft 25 rotates clockwise. When the interlocking plate 27 rotates clockwise, the light from the light-emitting element 33a disposed below is no longer blocked by the interlocking plate 27, and both light-receiving elements 33b receive the light. When both light receiving elements 33b receive light as described above, the determining means determines that "meandering is occurring to the left."

[0040] When the meandering detection device 21 detects that the belt 7 has meandered to the left, the meandering control air cylinder 11 is activated to horizontally tilt the driven roll 5 and move the belt 7 to the right in order to correct the meandering. Specifically, the left side of the driven roll 5 is horizontally tilted in the direction of increasing tension, and the right side is horizontally tilted in the direction of decreasing tension. This is based on the commonly known phenomenon that "the belt moves in the direction of decreasing tension," and as a result, the belt 7 moves to the right and the meandering is corrected.

[0041] On the other hand, when the belt 7 moves in the direction of the outline arrow shown in FIG. 7(c), the lower part of the shaft 25 is pressed against the side end surface of the belt 7, causing the shaft 25 to tilt counterclockwise.

[0042] As the shaft 25 tilts counterclockwise, the interlocking plate 27 connected to the shaft 25 also rotates counterclockwise. When the interlocking plate 27 rotates counterclockwise and the right end face of the belt 7 exceeds the reference range, as shown in Figure 7(c), the light from the light-emitting element 33a located above is also blocked by the interlocking plate 27, and both light-receiving elements 33b are not receiving light. When neither of the light receiving elements 33b receives light as described above, the determining means 35 determines that "meandering is occurring to the right."

[0043] When the meandering detection device 21 detects that the belt 7 has meandered to the right, the meandering control air cylinder 11 is activated to horizontally tilt the driven roll 5 and move the belt to the left in order to correct the meandering. Specifically, the right side of the driven roll 5 is tilted horizontally in the direction of increasing tension, and the left side is tilted horizontally in the direction of decreasing tension, so that the belt moves leftward and the meandering is corrected.

[0044] As described above, the meandering detection device 21 of this embodiment is equipped with the shaft 25 that tilts to follow the meandering of the belt 7, the interlocking plate 27 that interlocks with the movement of the shaft 25, and the first optical sensor 33 that detects the movement of the interlocking plate 27. Therefore, the occurrence of meandering can be detected without directly detecting the position of the belt 7 with an optical sensor, and therefore the device can be applied to a belt conveyor 1 used in an extremely low temperature environment.

[0045] In the above, the shaft 25, the interlocking plate 27, and the first optical sensor 33 are installed only on the right side of the belt 7 in the running direction (see FIG. 4), but the present embodiment is not limited to this. For example, as shown in FIG. 8, the shaft 25, the interlocking plate 27 (not shown), and the first optical sensor 33 (not shown) may be provided on both sides of the belt. 8, the meandering detection device 45 has shafts 25 in contact with both side end surfaces of the belt 7, and an interlocking plate 27 is connected to each shaft 25. Also, a first optical sensor 33 for detecting the movement of the interlocking plate 27 is provided near each of the left and right interlocking plates 27.

[0046] In this case, for example, when no meandering occurs, both light receiving elements 33b are set to be able to receive light. Furthermore, the first light sensor 33 on the left side is positioned so that the light from the light emitting element 33a is blocked when the interlocking plate 27 rotates a certain angle clockwise. Moreover, the first light sensor 33 on the right side is positioned so that the light from the light emitting element 33a is blocked when the interlocking plate 27 rotates a certain angle counterclockwise.

[0047] 8 configured as described above, when the belt 7 moves leftward in the figure, the interlocking plates 27 on both sides rotate clockwise, blocking the light of the left light-emitting element 33a. On the other hand, when the belt 7 moves rightward in the figure, the interlocking plates 27 on both sides rotate counterclockwise, blocking the light of the right light-emitting element 33a.

[0048] A determination means (not shown) of the meandering detection device 45 determines that "meandering is not occurring" when both light receiving elements 33b receive light. When the left light receiving element 33b does not receive light, it is determined that "meandering is occurring to the left." Similarly, when the right-side light receiving element 33b does not receive light, it is determined that "there is a meandering to the right." When meandering is detected by the meandering detection device 45, as described above, the meandering control air cylinder 11 horizontally tilts the driven roll 5 to move the belt 7 within the reference range, thereby controlling the meandering.

[0049] As described above, in the case of the meandering detection device 45 as shown in Figure 8, the occurrence of meandering can be detected without directly detecting the position of the belt 7 with an optical sensor, and the device can also be applied to a belt conveyor 1 used in an extremely low temperature environment.

[0050] [Embodiment 2] The meandering detection devices 21, 45 described in the first embodiment determine whether the belt 7 is meandering or not, and if so, whether it is meandering to the left or right, and based on this determination result, control the meandering by the meandering control air cylinder 11. However, even if the meandering control air cylinder 11 performs control correctly, there are cases where the belt 7 cannot be returned to within the reference range, and the belt 7 moves far beyond the reference range, and in this case, the belt conveyor 1 needs to be stopped. This embodiment relates to a belt meandering detection device that determines whether the belt 7 is meandering, and if so, in which direction it is meandering (left or right), and further detects when the side end face of the belt 7 enters a range where it must be stopped that greatly exceeds a reference range.

[0051] The meandering detector 47 in this embodiment is provided upstream in the belt running direction, i.e., near the driven roll 5, as in the first embodiment, and as shown in Figs. 9 and 10, the shaft 25, the interlocking plate 27, the cover member 31, and the spring 43 are provided on the back side of the shielding walls 17 on both sides. A first optical sensor 33 is provided on the back side (opposite side to the belt) of the shielding wall 17 on the right side in the figure, and a second optical sensor 49 is provided on the back side of the shielding walls 17 on both sides, and the first optical sensor 33 and the second optical sensor 49 are electrically connected to a determination means (not shown). The shaft 25, the interlocking plate 27, the cover member 31, the spring 45, and the first optical sensor 33 are the same as those in the first embodiment, so their explanations are omitted, and the second optical sensor 49 will be specifically described below.

[0052] <Second optical sensor> The second optical sensor 49 is an optical sensor having a plurality of light-emitting elements 49a and light-receiving elements 49b, similar to the first optical sensor 33 (see Figure 6), and in this embodiment, one is provided near each of the interlocking plates 27 on both sides, as shown in Figures 9 and 10. Normally (when the belt 7 is not in the stop-required range), the second optical sensors 49 are both disposed so that the light-receiving elements 49b receive the light emitted by the light-emitting elements 49a.

[0053] As described in the first embodiment, the determination means in this embodiment not only determines whether the side end face of the belt 7 is meandering beyond the reference range based on the input from the first optical sensor 33, but also determines whether the side end face of the belt 7 has entered the required stop range based on the input from the second optical sensor 49.

[0054] When the determining means determines that the belt 7 is meandering, the meandering control air cylinder 11 tilts the driven roll 5 horizontally to correct the meandering of the belt 7, as described above. Moreover, when it is determined that the side end face of the belt 7 has entered the area where the belt 7 needs to be stopped, the driving of the driving roll 3 is stopped, and the running of the belt 7 is stopped. A specific determination method in the determination means will be described later in the operation description.

[0055] The operation of the meandering detection device 47 in this embodiment configured as above will be described with reference to Figures 9 and 10. Note that in Figures 9 and 10, similar to Figure 7, the fixed plate 23 and the determination means are omitted. 9(a) shows a state where both side end faces of the belt 7 are within the reference range and no meandering occurs. As described in the first embodiment, the upper light receiving element 33b receives light and the lower light receiving element 33b does not receive light, so the determining means determines that "no meandering occurs."

[0056] 9(b) shows a state in which the belt 7 moves in the direction of the white arrow, and the left end face of the belt 7 exceeds the reference range but does not enter the required stop range. Both left and right shafts 25 tilt following the movement of the belt 7, and the interlocking plates 27 connected to the respective shafts 7 also rotate clockwise in conjunction with this. At this time, both light receiving elements 33b receive light, so as explained in the first embodiment, the determining means determines that "meandering is occurring in the left direction." In the state shown in FIG. 9B, the light receiving elements 49b receive light from both the left and right sides, so that the determining means determines that the vehicle "has not entered the required stop range."

[0057] When the meandering detection device 47 detects that the belt 7 has meandered to the left, the meandering control air cylinder 11 is activated to horizontally tilt the driven roll 5 and move the belt to the right in order to correct the meandering. At this time, if the meandering is correctly corrected, the state returns to that shown in FIG. 9(a). However, if the meandering of the belt 7 cannot be fully controlled for some reason, the belt 7 moves further to the left, and the left end face of the belt 7 enters the area where it must be stopped, as shown in FIG. 9(c).

[0058] 9(c), when the belt 7 moves further leftward, both of the left and right shafts 25 tilt further following the movement of the belt 7, and the interlocking plate 27 also rotates clockwise in conjunction with this. When the left and right interlocking plates 27 further rotate clockwise, the light receiving element 49b arranged on the left side is blocked by the interlocking plate 27 and does not receive light. When the left light receiving element 49b does not receive light as described above, the determining means determines that the vehicle is "entering the required stop range." When the meandering detection device 47 detects that the belt 7 has entered a range where the belt 7 needs to be stopped, it issues an alarm and stops the running of the belt 7.

[0059] FIG. 9 illustrates an example in which the belt 7 moves to the left, but the case in which the belt 7 moves to the right will be described with reference to FIG. FIG. 10(a) is the same as FIG. 9(a), and shows a state in which no meandering occurs. 10(b) shows a state in which the right end face of the belt 7 exceeds the reference range but does not enter the required stop range. At this time, the light receiving element 33b does not receive light from either of the elements, so the determination means determines that "there is a meandering to the right" as described in the first embodiment. Also, the light receiving element 49b receives light from both of the elements, so the determination means determines that "there is not entering the required stop range."

[0060] In order to correct the meandering, the meandering control air cylinder 11 is operated to move the belt 7 to the left. However, if for some reason the meandering of the belt 7 cannot be completely controlled, the belt 7 moves further to the right and the right end face of the belt 7 enters the area where it must be stopped, as shown in Figure 10(c).

[0061] 10(c), when the belt 7 moves further to the right, both of the left and right shafts 25 tilt further following the movement of the belt 7, and the interlocking plate 27 also rotates counterclockwise in conjunction with this. When the left and right interlocking plates 27 further rotate counterclockwise, the light receiving element 49b located above the light receiving element 33b is blocked by the interlocking plate 27 and does not receive light. When the right light receiving element 49b does not receive light as described above, the determining means determines that the vehicle is "entering the required stop range." When the meandering detector 47 detects that the belt 7 has entered a region where the belt 7 needs to be stopped, it issues an alarm and stops the belt from moving.

[0062] As described above, in the belt meandering detection device 47 of this embodiment, in addition to the configuration of embodiment 1, a second optical sensor 49 is provided, so that the occurrence of meandering and entry into a region requiring stopping can be detected without directly detecting the position of the belt 7 with an optical sensor, and therefore the device can be applied to a belt conveyor 1 used in an extremely low temperature environment.

[0063] In the above-mentioned first and second embodiments, the meandering detection devices 21, 45, 47 are installed near the driven roll 5 (upstream in the belt running direction), but the present invention is not limited to this. However, it is more preferable to install the devices near the driven roll 5 connected to the meandering control air cylinder 11, since this allows accurate meandering control of the belt 7.

[0064] In the first and second embodiments, the shape of the interlocking plate 27 is a rectangular plate with a part cut out to have a substantially L-shape, but the present invention is not limited to this. The shape of the interlocking plate 27 is not particularly important as long as the movement of the interlocking plate 27 allows the light receiving elements 33b and 49b to receive or not receive light.

[0065] Furthermore, a fan for preventing condensation may be provided near the first optical sensor 33 and the second optical sensor 49, and by using this in combination with the meandering detection device of the present invention, an even greater condensation prevention effect can be expected. EXAMPLES

[0066] An experiment was carried out to confirm the effect of using the meandering detection device of the present invention, and the results will be described below. In this embodiment, the meandering detection device 47 described in embodiment 2 was installed on the belt conveyor 1 described in Figure 2, and continuous operation was performed for 8 hours with the inside of the cold air supply tunnel 9 maintained at -120°C.

[0067] During continuous operation, no condensation or ice was observed on the first optical sensor 33 and the second optical sensor 49. In addition, since meandering control was performed normally, it was confirmed that the meandering of the belt can be correctly detected even in a belt conveyor used in an extremely low temperature environment. [Explanation of symbols]

[0068] 1. Conveyor belt 3 Driving Roll 5 Follower roll 7 Belt 9. Cold air supply tunnel 11. Snake control air cylinder 13 Fan 15 Shielding material 17 Shielding Wall 19 Screening floor 21 Meandering detection device (embodiment 1) 23 Fixed plate 25 Shaft 27 Interlocking plate 29 Insertion hole 31 Cover member 33 First light sensor 33a Light emitting element 33b Photodetector 35 Judgment means 37 Through hole 39 Connecting members 41 Shaft member 43 Spring 45 Meandering detection device (another aspect of embodiment 1) 47 Meandering detection device (embodiment 2) 49 Second optical sensor 49a Light emitting element 49b Photodetector

Claims

1. A belt meandering detection device for a belt conveyor used in an extremely low temperature environment, comprising: a contact movable member that comes into contact with a side end surface of the belt and moves in accordance with the meandering of the belt, an interlocking member that interlocks with the movement of the contact movable member, and a first optical sensor that detects the movement of the interlocking member; a determination means for determining whether or not the side end surface of the belt is meandering beyond a reference range based on an input from the first optical sensor; a shielding floor provided above a side end surface of the belt to block cold air; an insertion hole formed in the shielding floor, through which the shaft serving as the contact movable member is inserted in a tiltable state; a cover member having a through hole through which the shaft can pass and movably disposed on the shielding floor to cover the insertion hole, A belt meandering detection device, characterized in that the shaft passes through the through hole and the insertion hole, extends below the shielding floor, and contacts a side end surface of the belt.

2. The first optical sensor includes a plurality of light-emitting elements and a plurality of light-receiving elements, the light-emitting elements and the light-receiving elements being disposed on both sides of a plate-shaped interlocking plate that is the interlocking member, 2. The belt meandering detection device according to claim 1, wherein the determination means determines whether the belt is meandering, and if so, in which direction the belt is meandering, either to the left or to the right, based on a combination of whether the light-emitting element receives light from the light-receiving element or not.

3. The belt meandering detection device as described in claim 1 or 2, further comprising a second optical sensor that detects when the side end surface of the belt has entered a required stop range that is significantly beyond the reference range due to movement of the interlocking member, and the determination means determines whether or not the side end surface of the belt has entered the required stop range based on an input from the second optical sensor.

4. a shielding wall provided along a side end surface of the belt to block cold air; 4. The belt meandering detection device according to claim 1, wherein the first optical sensor is disposed on a rear side of the shielding wall.

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