JP3138283U - Dust collector - Google Patents

Abstract

Compressed air jetted from a nozzle above a bag filter during backwashing by providing a dust wiping aid that is inserted into a cylindrical body on the upper surface side of a partition plate on which the bag filter is disposed Can be distributed in the radial direction of the bag filter and sprayed directly on the upper end side of the bag filter. From the upper end side to the lower end side of the bag filter, the bag filter is inflated to the outside in order to remove dust attached to the outer surface. Providing dust collectors that can be reliably dropped, greatly reduce the load on the blower used for suction during dust collection, increase the effective filtration area during dust collection, improve dust collection efficiency, and save energy .
A partition plate (3) having a plurality of openings (3a) in which a bag filter (10) is disposed, a tubular body (4) projecting on the upper surface of the partition plate corresponding to the position of each opening, and a longitudinal direction And a dust wiping aid 5 having an upper end contracted portion 6, 6 b formed by contracting toward the upper end and disposed in a tubular body.
[Selection] Figure 1

Description

  The present invention performs filtration by sucking with a blower from the upper end side of the bag filter, and backwashing the bag filter by injecting compressed air from the nozzle disposed above the bag filter to the lower end side of the bag filter. It relates to a dust collector.

Conventionally, as a bag filter of a dust collector, a filter cloth that separates and collects dust by passing a dust-containing air flow, and a support frame (hereinafter referred to as a retainer) that supports the filter cloth from the inside in order to maintain the shape of the filter cloth. The thing provided with is used. When the dust collector is operated, the bag filter collects dust and the loss of suction force increases with the lapse of operation time. Therefore, it is necessary to remove the collected dust intermittently or continuously. For example, there are pulse jet type dust collectors described in (Patent Document 1), (Patent Document 2), and the like as those having such a dropping mechanism.
FIG. 7 (a) is a schematic cross-sectional view showing the main part of the bag filter during dust collection in a conventional dust collector equipped with a pulse jet type dusting mechanism, and FIG. 7 (b) is a pulse jet type dusting out. It is a principal part schematic cross section which shows the state of the bag filter at the time of dusting-off (at the time of backwashing) in the conventional dust collector provided with the mechanism.
In FIG. 7, reference numeral 50 denotes a bag filter having a length of 2000 mm to 9000 mm arranged in a conventional dust collector provided with a pulse jet type wipe-off mechanism 70, 51 is a retainer of the bag filter 50, and 52 is an upper end portion of the retainer 51. The venturi tube 52a is fixed at the top, 52a is a flange at the upper end of the venturi tube 52, 55 is a cylindrical filter cloth disposed on the outer periphery of the retainer 51, and 60 is a partition plate (cell) of the dust collector that holds the bag filter 50. A plate 70, 70 a is a nozzle of a pulse jet type wiping mechanism 70 that is disposed above the venturi tube 52 and injects compressed air toward the venturi tube 52.

  As shown in FIG. 7 (a), the dust-containing airflow that has flowed into the dust-collecting chamber from the dust-collecting airflow inlet of the dust collector is sucked by a blower (negative pressure -0.12 kPa to -0.11 kPa). The dust is removed from the outside of the filter cloth 55 and flows into the filter cloth 55, the dust is collected on the outer periphery of the filter cloth 55, and the clean air stream in which the dust is separated and collected is discharged from the venturi pipe 52. A nozzle 70a of a wiping mechanism 70 is disposed above the venturi tube 52. As shown in FIG. 7B, compressed air is supplied from the nozzle 70a to the inside of the filter cloth 55 from the venturi tube 52 at regular intervals. The dust sprayed and adhered to the filter cloth 55 is instantaneously removed to the outside of the filter cloth 55.

On the other hand, new materials such as filter cloths and molded filters have been developed for the purpose of downsizing dust collectors and improving filtration performance.
For example, (Patent Document 3) states that “a filter cloth is composed of a base fabric layer made of inorganic fibers and a filter layer made of organic heat-resistant fibers on one side of the base fabric layer, and at least the filter layer in the filter cloth is heat-resistant. "A molded filter molded into a predetermined shape by impregnating and solidifying with a thermosetting thermosetting resin."
JP 10-2111410 A Japanese Patent Laid-Open No. 8-299732 JP 2007-83163 A

  However, with respect to the pulse jet type dust collector, the operation of the filter cloth 55 at the time of dust removal was observed, and when the pulse jet (compressed air) was injected from the nozzle 70a, the injection speed was high, and the upper end side of the retainer 51 In the vicinity of the outer periphery of the Venturi tube 52, a negative pressure is generated due to the Venturi effect, and as shown in FIG. 7B, the filter cloth 55 is attracted to the retainer 51 and is in a suction state. It was found that the dust at the upper end was not removed. This phenomenon was confirmed in the same manner even when the venturi tube 52 was not provided. In addition, in the bag filter using a chrysanthemum shaped filter formed by pleats as in (Patent Document 3) instead of the cylindrical filter cloth 55, dust cannot be removed on the upper end side. It was confirmed.

From the above, the following problems in the prior art have been clarified.
(1) Even if a positive pressure pulse jet (compressed air) is injected, the injection speed is fast (about 90 m / s), so that positive pressure is generated only for a moment (about 0.02 seconds), The filter cloth 55 cannot react, and at the upper end of the filter cloth 55, it is between the positive pressure in the filter cloth 55 by the pulse jet and the suction negative pressure of the blower on the upper part of the partition plate (cell plate) 60. Since the pressure is generated, the inside of the filter cloth 55 is in a vacuum state, and the filter cloth 55 is strongly attracted to the retainer 51 side and remains stuck, so that the dust at the upper end of the filter cloth 55 is removed. This is not possible and the dust collection efficiency decreases.
(2) When the high-speed pulse jet (compressed air) passes through the venturi tube 52, the pressure on the inner upper end side of the retainer 51 (below the venturi tube 52) is reduced, and the dust-containing airflow outside the bag filter 50 Is sucked into the retainer 51 through the filter cloth 55, but the dust-containing airflow cannot pass through the filter cloth 55 in a short time due to the resistance of the filter cloth 55, and the clean airflow is supplied to the interior of the retainer 51. Negative pressure is generated in time. Both the negative pressure and the negative pressure due to the blower suction cause the filter cloth 55 to be in a suction state while being strongly attracted to the outer periphery of the retainer 51, and the filter cloth 55 is rubbed by the retainer 51 and easily damaged, resulting in lack of long life. .
(3) In particular, at the position of the boundary where the negative pressure of 500 mm to 600 mm changes from the upper end of the filter cloth 55 to the positive pressure, the filter cloth 55 is extremely attracted inward and outward, and damage due to bending becomes significant.
(4) When the discharge pressure of the pulse jet is increased, when the venturi tube 52 is removed, or when the venturi tube 52 is attached to the outside of the retainer 51, the negative pressure at the upper end of the filter cloth 55 is further increased. The filter cloth 55 is easily damaged. Therefore, the pressure of the pulse jet is usually in the range of about 196 kPa to 686 kPa, but in order to prevent the filter cloth 55 from being damaged, there are places where the pressure of the pulse jet is suppressed to 392 kPa or less. In the retainer, the pulse jet may not reach the lower end of the retainer 51, and dust may not be able to be removed at the upper and lower ends.
(5) Since the venturi tube 52 is disposed inside the retainer 51, the cross-sectional area of the flow path at the upper end of the retainer 51 is reduced, the flow velocity of the clean air flow during blower suction is increased, and the pressure loss is reduced. To increase. Further, because of the flange portion 52a at the upper end of the venturi tube 52, there is no passage of the clean air flow around the venturi tube 52, the clean air flow stays and the suction efficiency decreases.
(6) When a plurality of openings (blower suction holes) are provided on the circumference of the flange 52a at the top of the venturi pipe 52 and the opening area is widened, the load on the blower during dust collection can be reduced. Although the suction force can be increased, when a pulse jet is ejected when dust is removed, the positive pressure in the filter cloth 55 by the pulse jet and the negative suction pressure of the blower on the upper part of the partition plate (cell plate) 60 And the negative pressure at the upper end of the filter cloth 55 increases, and the positive pressure of the pulse jet does not reach the lower end of the retainer 51, resulting in an ineffective dust removal effect. It will be enough.
(7) The molded filter can shorten the overall length by increasing the filtration area per unit volume, reduce the size of the dust collector, and is excellent in space saving. As in the case of the filter cloth 55, the dust could not be removed at the upper end, resulting in a decrease in dust collection efficiency.
(8) If the dust collector continues to be used in a state where dust attached to the upper end of the bag filter 50 cannot be removed, dust will continue to accumulate and a dust bridge will be generated between the surface of the bag filter 50 and the partition plate 60. However, there is a problem that the partition plate 60 is corroded by moisture absorption.

  The present invention solves the above-mentioned conventional problems, and by providing a dust wiping aid that is inserted into the cylindrical body on the upper surface side of the partition plate on which the bag filter is disposed, the bag filter is backwashed. Sometimes, a part of the compressed air sprayed from the upper nozzle of the bag filter can be dispersed in the radial direction of the bag filter and sprayed directly on the upper end side of the bag filter, sequentially from the upper end side to the lower end side of the bag filter, It can inflate outwards and reliably remove dust adhering to the outer surface, and the cross-sectional area of the flow path at the upper end of the bag filter can be expanded compared to the conventional venturi type. The purpose is to provide a dust collector that can greatly reduce the load on the blower used for suction, expand the effective filtration area during dust collection, improve dust collection efficiency, and excel in energy saving. .

In order to solve the above conventional problems, a dust collector of the present invention has the following configuration.
The dust collector according to claim 1 of the present invention performs filtration by sucking with a blower from the upper end side of the bag filter, and supplying compressed air from the nozzle disposed above the bag filter to the lower end side of the bag filter. A dust collector that performs backwashing of the bag filter by spraying, the partition plate having a plurality of openings in which the bag filter is disposed, and corresponding to the positions of the openings on the upper surface of the partition plate A tubular body projecting and a dust removal aid having an upper end contraction portion formed by contracting toward the upper end at the upper end portion in the longitudinal direction and disposed by being inserted into the tubular body, It has the composition provided with.
With this configuration, the following effects can be obtained.
(1) Since the upper end contraction part formed by shrinking toward the upper end is formed at the upper end part in the longitudinal direction of the dust removal aid, compressed air is injected from the nozzle disposed on the upper part of the bag filter during backwashing. When this is done, a part of the compressed air is reflected by the inclined surface of the upper end contraction part to be distributed in the radial direction (outer peripheral direction) of the bag filter, and can be directly blown to the inner periphery of the upper end side of the bag filter. The bag filter can inflate outward almost uniformly over the entire length from the upper end to the lower end of the bag filter. Excellent, can improve the dust collection efficiency by expanding the effective filtration area at the time of dust collection, and excellent energy saving.
(2) With the dust removal aid, dust attached to the upper end of the bag filter can be surely removed, so that dust does not accumulate, dust bridges can be prevented, and partition plates can be prevented from corroding. And the long life of the dust collector is excellent.
(3) Since the tubular body into which the dust wiping aid is inserted protrudes from the upper surface side of the partition plate on which the bag filter is disposed, the existing bag filter should be used as it is attached to the partition plate. It is possible to improve the dust collection efficiency without remodeling, and it is easy to handle.

Here, the dust wiping aid can be made of metal or synthetic resin depending on the environment (temperature) to be used, and the shape is a shape having an upper end contraction portion at the upper end in the longitudinal direction. If it is. As the shape of the upper end contraction portion of the dust removal aid, a conical shape, a hemispherical shape, an elliptical hemispherical shape, a bullet shape, a polygonal pyramid shape, and the like are preferably used. In particular, when formed with an axisymmetric rotating body, the flow of compressed air at the time of backwashing and the flow of clean airflow at the time of dust collection can be made uniform over the entire circumference, resulting in excellent efficiency.
A cylindrical part or a prismatic part having the same shape as the bottom part of the upper contraction part may be formed at the lower part of the upper contraction part, or a lower contraction part that contracts toward the lower end is formed at the lower end part in the longitudinal direction. Also good.

The top angle when the upper end contraction part of the dust wiping aid is formed into a conical shape or a pyramid shape varies depending on the length of the upper end contraction part and the maximum cross-sectional area (horizontal projection area), but 45 degrees to 100 degrees, Preferably, it is desirable to form at 65 to 75 degrees.
As the top angle of the top contraction part of the dust removal aid becomes smaller than 65 degrees, the compressed air injected during backwashing becomes difficult to disperse to the outer periphery of the dust removal aid, reducing the negative pressure reduction effect. The amount of compressed air that reaches the lower end of the bag filter during backwashing decreases as it becomes larger than 75 degrees. However, there is a tendency that dust is not sufficiently removed on the lower end side of the bag filter. In particular, when the angle of the top of the upper end contraction portion of the dust removal aid is smaller than 45 degrees, the compressed air injected during backwashing easily escapes downward, making it difficult to disperse the dust removal aid on the outer peripheral side. The negative pressure reduction effect is remarkably reduced and it becomes difficult to wipe off dust at the upper end of the bag filter. When the temperature exceeds 100 degrees, the cross-sectional area of the flow path at the upper end of the tubular body or the bag filter is insufficient. The amount of compressed air that reaches the bottom end of the bag filter is significantly reduced, making it difficult to remove dust on the bottom end of the bag filter and increasing the load on the blower during dust collection, resulting in poor energy savings. Neither is preferred.

The dust wiping aid may be fixed to the tubular body by suspending the dust wiping aid from the upper end side of the tubular body or supported from the inner peripheral side of the tubular body. Good.
The fixing member for attaching the dust wiping aid to the tubular body may be any member that can fix the dust wiping aid to the tubular body, but between the tubular body serving as the flow path and the dust wiping aid. A structure and arrangement that do not hinder the flow of the air flow are preferable.
Specifically, a hanging part formed of a rod-shaped member such as a metal wire is disposed in the longitudinal direction of the tubular body on the outer periphery of the dust removal aid, and bent from the tip to the outer peripheral side of the tubular body. Fixing the extended part by welding, locking, fitting, screwing, etc. to the upper end of the tubular body or the annular flange provided at the upper end, etc. A rod-like member such as a metal wire arranged radially in the radial direction of the tubular body on the outer periphery, and the tip thereof fixed to the inner wall of the tubular body by welding or the like is preferably used.
Just by locking the extension part to the upper end part or annular flange part of the tubular body, it can be fixed by the weight of the dust wiping aid, but the upper end part or annular flange part of the tubular body is provided with a fitting recess or clamping part In this case, it is possible to effectively hold the extended portion and effectively prevent the dust removal aid from being displaced, rotated, and rattling. In addition, when a flat annular member is disposed at the tip of the extension part and screwed, or when the extension part and the tubular body or the annular flange part are directly welded, the dust wiping aid is securely and firmly secured. The fixing stability is excellent.

The number of fixing members is preferably 2-6. When the number of the fixing members is one, the cantilever is supported and the fixing reliability is lacking. As the number of fixing members increases, the resistance of the flow path increases and the flow of the air flow is easily obstructed. There is a tendency for the efficiency to decrease, both of which are not preferred. The fixing members are preferably arranged at equiangular intervals in the circumferential direction of the dust removal aid. This is because the flow of airflow is uniform over the entire circumference, dust can be completely removed, and the filtration performance is stable.
The installation height of the dust removal aid depends on the area ratio between the maximum cross-sectional area (horizontal projection area) of the dust removal aid and the opening area of the tubular body, the inclination angle, length, and shape of the top contraction part. Can be appropriately selected. For example, it may be inserted so that only a part of the upper end side of the upper contraction part or only the upper end contraction part fits in the tubular body, and the other part protrudes to the bag filter side. However, you may make it fit in the inside of a tubular body. In particular, if the entire length of the dust wiping aid fits within the tubular body, the bag filter can be easily replaced without being caught by the dust wiping aid when the bag filter is removed from the side. Can be performed, and is excellent in maintainability.

  As the bag filter of this dust collector, a cylindrical filter cloth covered on the outer periphery of the retainer or a molded filter is preferably used. A material, a shape, or the like can be selected as appropriate according to the application or use environment.

Invention of Claim 2 is a dust collector of Claim 1, Comprising: The said dust-wiping aid has the lower end shrinkage | contraction part formed by shrink | contracting toward the lower end in the lower end part of a longitudinal direction. It has a configuration.
With this configuration, in addition to the operation obtained in the first aspect, the following operation can be obtained.
(1) Since the lower end contraction part formed by contracting toward the lower end is formed at the lower end part in the longitudinal direction of the dust removal aid, the filtered clean airflow is contracted at the lower end when sucked with a blower during dust collection. It can be smoothly moved to the upstream side along the inclined surface of the part, and there is little pressure loss and excellent suction efficiency.
(2) Compressed air injected at the time of backwashing can be rectified by the lower end contraction part, the compressed air can easily reach the lower end side of the bag filter, and the dust adhering to the surface of the bag filter can be efficiently spread over the entire length. Can be withdrawn.

  Here, as the shape of the lower end contraction portion of the dust wiping aid, a conical shape, a hemispherical shape, an elliptical hemispherical shape, a bullet shape, and the like are preferably used. When the lower end contraction part of the dust removal aid is formed in a conical shape or a pyramid shape, the apex angle varies depending on the length of the lower end contraction part and the suction pressure of the blower, but it is 40 to 90 degrees, preferably 60 degrees. It is desirable to form at -80 degrees. As the angle of the top of the lower end contraction part of the dust removal aid becomes smaller than 60 degrees, the length of the lower end contraction part becomes longer, and there is a tendency that workability and handleability tend to be lowered, and it is larger than 80 degrees. Accordingly, there is a tendency that the clean airflow sucked during dust collection tends to be difficult to move smoothly along the lower end contraction portion. In particular, when the angle of the top of the lower end contraction part of the dust removal aid is smaller than 40 degrees, the productivity is remarkably lowered, handling becomes difficult and lacks in fixing stability. The sucked clean airflow hits the lower end contraction portion and is dispersed in the outer peripheral direction of the bag filter, the suction efficiency is lowered and the filtration performance becomes insufficient.

  The maximum cross-sectional area (horizontal projection area) of the dust removal aid varies depending on the length and shape of the upper end contraction part and the lower end contraction part, but is 0.2 to 0.4 times the opening area of the tubular body (bag filter). It is preferable to form it twice. As the maximum cross-sectional area (horizontal projected area) of the dust removal aid becomes smaller than 0.2 times the opening area of the tubular body, the compressed air injected during backwashing is dispersed around the dust removal aid. Tends to be difficult, and the dust at the upper end of the bag filter tends to be insufficiently removed, and as it becomes larger than 0.4 times, the cross-sectional area of the flow path at the upper end of the tubular body and the bag filter becomes insufficient. The amount of compressed air that reaches the lower end of the bag filter during backwashing is likely to be insufficient, and the dust at the lower end is insufficiently discharged, and the load on the blower during dust collection increases, resulting in improved driving efficiency. There is a tendency to be lowered easily, and neither is preferable. By forming the maximum cross-sectional area (horizontal projection area) of the dust wiping aid to 0.2 to 0.4 times the opening area of the tubular body (bag filter), the flow passage is cut compared to conventional venturi pipes. The area can be increased, and the load on the blower used for suction during dust collection can be greatly reduced to improve the energy saving performance of the dust collector.

As for the overall shape of the dust wiping aid when it has an upper end contraction part and a lower end contraction part, a conical top type (abacus bead shape) or a conical shape in which the conical upper end contraction part and the lower end contraction part are arranged vertically symmetrically A spindle type in which a lower end contraction portion such as a hemispherical shape, an elliptical hemisphere shape, or a bullet shape is combined with the upper end contraction portion is particularly preferably used. This is because the rectifying effect is excellent and the flow of airflow is smoothed to reduce pressure loss.
The upper end contraction part and the lower end contraction part may be formed continuously, or a cylindrical or prismatic body may be formed between the upper end contraction part and the lower end contraction part. By providing the cylindrical body portion or the prismatic body portion, the total length of the dust removal aid can be adjusted or used for attachment to the tubular body.

The invention described in claim 3 is the dust collector according to claim 1 or 2, wherein the upper contraction part or the lower contraction part is conical, hemispherical, elliptical hemispherical, bullet-shaped, spherical, It has the structure currently formed in any one shape of pyramid shape.
With this configuration, in addition to the operation obtained in the first or second aspect, the following operation can be obtained.
(1) When the upper end contraction part of the dust wiping aid is formed in any one of a conical shape, a hemispherical shape, an elliptical hemispherical shape, a bullet shape, a spherical shape, and a polygonal pyramid shape, during backwashing The injected compressed air can be radially distributed from the center (axial center) of the tubular body toward the outer peripheral side, and the upper end side of the bag filter can be surely inflated outward over the entire circumference. It is possible to efficiently remove dust.
(2) When the lower end contraction part of the dust wiping aid is formed in any one of conical, hemispherical, elliptical hemispherical, bullet-shaped, spherical, and polygonal pyramids, during dust collection The sucked clean airflow can be moved upstream along the entire circumference of the lower end contraction part, the load on the blower can be reduced, and the energy saving property is excellent.

Invention of Claim 4 is the dust collector of any one of Claims 1 thru | or 3, Comprising: The said bag filter was covered by the outer periphery of the chrysanthemum type | mold molded filter or retainer, and the said retainer It has the structure which is a cylindrical filter which has a cylindrical filter cloth.
With this configuration, in addition to the action obtained in any one of claims 1 to 3, the following action is obtained.
(1) By using a chrysanthemum shaped filter, the filtration area per unit volume can be greatly increased compared to a cylindrical filter, and the overall length of the bag filter can be shortened to reduce the size of the apparatus. It is excellent in space saving and maintenance.
(2) When the bag filter is a cylindrical filter having a retainer and a cylindrical filter cloth covered on the outer periphery of the retainer, the shape of the filter cloth can be maintained by the retainer, and the bag filter is lengthened. The filtration area can be expanded, and the filtration efficiency and energy saving are excellent.

Here, the molding filter can be formed into a chrysanthemum shape by pleating. A retainer may be inserted inside the molded filter to maintain the shape. However, if the length of the molded filter is short, the structure can be reduced by reducing the number of vertical wires or increasing the interval between the fixing rings. It may be simplified or a retainer may not be used.
For example, as a molded filter in the case where heat resistance is required, a polytetrafluoroethylene (PTFE) fiber or an inorganic fiber base fabric having heat resistance such as glass fiber and excellent in shape stability at high temperature can be used. What formed the filtration layer by implanting the organic fiber excellent in heat resistance and filterability like a polyphenylene sulfide (PPS) fiber with a needle punch etc. is used suitably. In general, where heat resistance is not required, filter cloth formed of a woven or non-woven fabric of synthetic fiber such as polyester, nylon, or acrylic is impregnated with a thermosetting resin such as phenol resin or melamine resin. Those molded into a predetermined shape such as a pleated shape by heating to a predetermined temperature and curing the resin are preferably used.

As described above, according to the dust collector of the present invention, the following advantageous effects can be obtained.
According to the device of claim 1,
(1) A part of the pulse jet (compressed air) injected during backwashing is dispersed in the radial direction (peripheral direction) of the bag filter by a dust wiping aid and blown directly on the upper end of the bag filter. By inflating outwards almost uniformly over the entire length from the upper end side to the lower end side, the dust attached to the outer surface of the bag filter can be surely removed to increase the effective filtration area. A dust collector capable of improving maintainability and dust collection efficiency and improving energy saving can be provided.
(2) With the dust removal aid, dust attached to the upper end of the bag filter can be surely removed, so that dust does not accumulate, dust bridges can be prevented, and partition plates can be prevented from corroding. Thus, it is possible to provide a dust collector with excellent long life.

According to the device described in claim 2, in addition to the effect of claim 1,
(1) The clean airflow sucked and filtered by the blower during dust collection can be guided by the lower end contraction part of the dust wiping aid and smoothly moved to the upstream side of the bag filter, reducing the pressure loss of the bag filter. Thus, a dust collector capable of improving the suction efficiency can be provided.

According to the device described in claim 3, in addition to the effect of claim 1 or 2,
(1) Compressed air injected during backwashing can be distributed almost uniformly from the center (axial center) of the bag filter toward the outer periphery at the upper end contraction part, and the upper end side of the bag filter can be distributed all around. It is possible to provide a dust collector that can be reliably inflated to the outside and can improve the efficiency of dust removal of the bag filter.
(2) The clean airflow sucked during dust collection can be moved substantially uniformly along the entire circumference of the lower-end contracted portion to the upstream side, and the load on the blower can be reduced to improve energy saving. A dust collector can be provided.

According to the invention described in claim 4, in addition to the effect of any one of claims 1 to 3,
(1) By combining a chrysanthemum shaped filter with a large filtration area per unit volume compared to a cylindrical filter and a dust removal aid, the original filtration area of the molded filter can be used effectively. The overall length can be further shortened to reduce the size of the apparatus, and it is excellent in space saving and can further improve the dust collection efficiency.
(2) By combining a cylindrical filter that is easy to lengthen with a dust removal aid, the bag filter can be lengthened and the filtration area can be expanded without degrading the efficiency and energy saving of filtration. The filtration performance can be improved.

The best mode for carrying out the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a cross-sectional front view of an essential part of a dust collector in Embodiment 1 of the present invention.
In FIG. 1, reference numeral 1 denotes a dust collector according to the first embodiment provided with a pulse jet type wiping mechanism 2, and 2 a a pulse jet that is arranged above a bag filter 10 to be described later and injects compressed air toward the bag filter 10. Nozzle of the shape dropping mechanism 2, 3 is a partition plate (cell plate) of the dust collector 1 that holds the bag filter 10, 3 a is a plurality of openings of the partition plate 3 in which the bag filter 10 is disposed, and 3 b is a partition plate 3 is a fixing member that protrudes from the lower surface of 3 and fixes the bag filter 10 by screwing. 4 is a tubular body that protrudes from the upper surface of the partition plate 3 corresponding to the position of each opening 3a, and 4a is a tubular body 4. The lower flange 4b is fixed to the partition plate 3 and 4b is the upper flange formed at the upper end of the tubular body 4, and 5 is formed in a conical frame type (abacus bead) and is the central part of the tubular body 4. Interpolated in The dust wiping aid 6 is disposed at the upper end of the longitudinal direction, the upper end shrinking portion 6 of the dust wiping aid 5 formed in a conical shape by contracting toward the upper end, and the upper shrinking portion 6 a. , 7 is a lower end contraction part of the dust wiping aid 5 formed in a conical shape by contracting to the lower end part in the longitudinal direction, 7a is a top part of the lower end contraction part 7, and 8 is an upper end contraction part 6 And a cylindrical body portion 9 formed between the lower end shrinkage portion 7 and a metal wire 9 such as stainless steel, and are arranged at three positions at equal angular intervals on the outer periphery of the cylindrical body portion 8 of the dust removal aid 5. A fixing member 9a for fixing the dust wiping aid 5 to the tubular body 4, and a suspension part 9a of the fixing member 9 extending from the cylindrical body portion 8 of the dust wiping aid 5 toward the upper end of the tubular body 4. , 9b bend and extend from the tip of the hanging part 9a to the outer peripheral side of the tubular body 4 The extending portion 10 of the fixing member 9 locked to the upper flange 4b is a bag filter 10 detachably disposed in each opening 3a of the partition plate 3 by a fixture 3b, and 10a is a chrysanthemum shaped filter The filter body of the bag filter 10 using 11, 11 is a flange portion disposed at the upper end of the bag filter 10, 11 a is a seal portion disposed on the upper surface of the flange portion 11 and seals between the partition plate 3, and 11 b A bottom cover 12 provided at the lower end of the bag filter 10 is a support plate that supports the flange portion 11 of the bag filter 10 inserted from above and is fixed to the fixture 3b by screws.

Next, the detail of the attachment method of a bug filter is demonstrated.
FIG. 2 is a schematic perspective view of a main part showing the attachment state of the bag filter to the support plate of the dust collector in the first embodiment of the present invention.
In FIG. 2, reference numeral 12 a denotes a plurality of bag filter insertion holes formed in the support plate 12 in order to suspend and fix the bag filter 10.
First, as shown in FIG. 2, the bag filter 10 is inserted into the bag filter insertion hole 12 a from above the support plate 12 and supported by the flange portion 11.
Next, the support plate 12 on which the plurality of bag filters 10 are suspended and held is fixed to the fixture 3b of the partition plate 3 by screwing as shown in FIG.
When exchanging the bag filter 10 or the like, after removing the support plate 12 from the fixture 3b, the support plate 12 can be pulled out to replace the plurality of bag filters 10 together. Excellent maintainability.

Next, the details of the dust wiping aid will be described.
FIG. 3 is a cross-sectional front view of an essential part showing an attached state of the dust wiping aid used in the dust collector in Embodiment 1 of the present invention.
In FIG. 3, a is the diameter of the tubular body 4, l ₁ is the length of the tubular body 4, x ₁ is the length of the upper end contraction portion 6 of the dust removal aid 5, and x ₂ is the dust removal aid 5. The length of the lower end contraction portion 7, y ₁ is the length of the cylindrical body portion 8 of the dust removal aid 5, z ₁ is the diameter of the cylindrical body 8 of the dust removal aid 5, and α ₁ is the dust removal aid. The angle of the top portion 6 a of the upper end contraction portion 6 of the tool 5, α ₂ is the angle of the top portion 7 a of the lower end contraction portion 7 of the dust removal aid 5.

By forming the dust wiping aid 5 with an axisymmetric rotating body having an upper end contraction portion 6 and a lower end contraction portion 7 at the upper end and the lower end, respectively, the flow of compressed air during backwashing and the flow of clean airflow during dust collection It can be made uniform over the entire circumference, and the filtration can be efficiently performed without spots on the entire outer circumference of the bag filter 10.
Further, a cylindrical body portion 8 is formed between the upper end contraction portion 6 and the lower end contraction portion 7, and the hanging portion 9 a of the fixing member 9 is fixed. In the present embodiment, a locking hole is formed in the cylindrical body portion 8 of the dust removal aid 5 and the suspension portion 9a is inserted to fix the suspension portion. You may fix the front-end | tip part of the part 9a by welding. By arranging the fixing member 9 on the outer peripheral portion of the dust wiping aid 5 at equiangular intervals, the dust wiping aid 5 is aligned with the axial center of the tubular body 4 and easily fixed. Can do.

Even if the extension portion 9b of the fixing member 9 is simply locked to the upper flange 4b of the tubular body 4, it can be fixed by the weight of the dust wiping aid 5 but when the fitting recess or the clamping portion is provided in the upper flange 4b, The extended portion 9b can be securely held to effectively prevent misalignment, rotation, rattling, etc. of the dust removal aid 5. Further, when a flat annular member is disposed at the tip of the extended portion 9b and screwed to the upper flange 4b, or when the extended portion 9b and the upper flange 4b are directly welded, the tubular body 4 and the duster The drop assisting tool 5 can be firmly fixed, and the fixing stability is excellent.
In the present embodiment, the three fixing members 9 are used, but the number of the fixing members 9 can be appropriately selected from 2 to 6. If the number of the fixing members 9 is one, it becomes cantilevered support and the fixing reliability is lacking. As the number of fixing members 9 increases, the flow of airflow is easily inhibited, and the resistance of the flow path increases. This is because the suction efficiency tends to decrease.
In addition, it is preferable to arrange the fixing members 9 at equiangular intervals in the circumferential direction of the dust removal aid 5. This is because the flow of airflow is uniform over the entire circumference, dust can be completely removed, and the filtration performance is stable.

The maximum cross-sectional area of the dust brushing aid 5 (horizontal projection area = πz 1 ^_2/4), the length (x _{1, x 2)} of the upper contracted section 6 and the lower constriction 7 also varies and shape, tubular was formed in 0.2 times to 0.4 times the body 4 opening area of the (bag filter ^{10) (= πa 2/4} ). As the maximum cross-sectional area (horizontal projection area) of the dust removal aid 5 becomes smaller than 0.2 times the opening area of the tubular body 4 (bag filter 10), the compressed air injected during backwashing is aided in dust removal. It becomes difficult to disperse to the outer periphery of the tool 5, and there is a tendency that dust is not sufficiently removed from the upper end portion of the bag filter 10. channel cross-sectional area ^{(πa 2/4-πz 1} 2/4) becomes insufficient, liable to insufficient amount of compressed air to reach during the backwash to the lower end side of the bag filter 10, at the lower end side of the bag filter 10 This is because it is found that there is a tendency that the dust is not sufficiently removed and the load of the blower at the time of dust collection increases and the driving efficiency tends to decrease.
By inserting the dust wiping aid 5 in the center of the tubular body 4, the cross-sectional area of the flow path can be increased compared to the conventional venturi tube, and the load of the blower used for suction during dust collection is greatly increased. The energy saving performance of the dust collector 1 can be improved.

Angle alpha ₁ of the top 6a of the upper constriction 6 Dust brushing aid 5, the length x ₁ and the maximum cross-sectional area (horizontal projection area = πz 1 ^_2/4) of the upper contracted section 6 also vary, but 65 Formed at a degree to 75 degrees. As _first angle α of the apex portion 6a of the upper constriction 6 Dust brushing aid 5 is less than 65 degrees, the compressed air injected during backwashing is hardly dispersed in the outer peripheral side of the down aid 5 payments dust, The negative pressure reduction effect tends to be reduced, and there is a tendency that dust is not sufficiently removed at the upper end of the bag filter 10, and as it becomes larger than 75 degrees, it reaches the lower end of the bag filter 10 during backwashing. This is because it has been found that the amount of compressed air that reaches the surface tends to be reduced, and dust tends to be insufficiently discharged on the lower end side of the bag filter 10.
The angle α ₂ of the apex portion 7a of the lower end contraction portion 7 of the dust removal aid 5 varies depending on the length x ₂ of the lower end contraction portion 7 and the suction pressure of the blower, but is formed at 60 degrees to 80 degrees. As the angle alpha ₂ of dust brushing the top portion 7a of the lower constriction 7 of the aid 5 is less than 60 degrees, it may increase the length x ₂ of the lower constriction 7, processability, handleability tends to decline This is because it has been found that as the temperature becomes larger than 80 degrees, the clean air current sucked during dust collection tends to be difficult to move smoothly along the lower end contraction portion 7.

  In the present embodiment, only the upper end contraction portion 6 of the dust wiping aid 5 is inserted so as to be accommodated in the tubular body 4, and the other portions (the lower end contraction portion 7 and the cylindrical body portion 8) protrude toward the bag filter 10 side. However, the mounting height of the dust wiping aid 5 (the length of the tubular body 4) is not limited to this, and the maximum cross-sectional area (horizontal projection area) of the dust wiping aid 5 is not limited to this. ) And the opening area of the tubular body 4 and the inclination angle, length, shape, and the like of the top contraction portion 6 can be selected as appropriate. For example, a part of the upper end side of the upper end contraction portion 6 of the dust removal aid 5 may be accommodated in the tubular body 4, or the entire length of the dust removal aid 5 may be accommodated in the tubular body 4. May be.

About the dust collector in Embodiment 1 of this invention comprised as mentioned above, the usage method is demonstrated below.
4 (a) is a schematic cross-sectional view of the main part showing the state of the bag filter during dust collection of the dust collector in the first embodiment of the present invention, and FIG. 4 (b) is a diagram of the dust collector in the first embodiment of the present invention. It is a principal part schematic sectional drawing which shows the state of the bag filter at the time of backwashing.
At the time of dust collection, as shown in FIG. 4A, the clean airflow that flows in from the outside of the bag filter 10, dust is collected on the outer periphery of the bag filter 10, and dust is separated and collected is transformed into the bag filter 10. Is discharged from the opening 3a of the partition plate 3 on the upper end side. At this time, the clean airflow moving from the lower end side to the upstream side of the bag filter 10 can move smoothly along the outer periphery of the dust removal aid 5 formed in a substantially spindle shape, and the dust removal aid 5 does not hinder the flow of airflow.

When backwashing is performed at regular intervals, as shown in FIG. 4B, compressed air is jetted from the nozzle 2 a of the dropping mechanism 2 toward the inside of the bag filter 10. At this time, a part of the compressed air moving from the upper end side to the lower end side of the bag filter 10 collides with the upper end contraction portion 6 of the dust removal aid 5 and is dispersed in the radial direction (outer peripheral direction) of the bag filter 10. As a result, the occurrence of negative pressure at the upper end of the bag filter 10 is prevented, the bag filter 10 swells outward substantially uniformly over the entire length, and the dust adhering to the outer surface of the bag filter 10 is instantaneously wiped off. It is.
The suction negative pressure by the blower during dust collection increases at the upper end of the bag filter 10 close to the blower, so that the amount of dust attached to the upper end of the bag filter 10 increases. By preventing the generation of negative pressure at the time of washing, the positive pressure on the upper end side of the bag filter 10 near the nozzle 2a for jetting the pulse jet can be made higher than the lower end side, so that dust adhering to the outer surface of the bag filter 10 can be removed. Can be effectively eliminated.
In the present embodiment, a chrysanthemum-shaped molded filter is used as the filter body 10a of the bag filter 10, but the material, shape, and the like can be selected as appropriate according to the application, usage environment, and the like of the dust collector 1. Similarly, a cylindrical filter cloth covered on the outer periphery of the retainer can be used.

Next, a modified example of the dust wiping aid used in the dust collector in Embodiment 1 of the present invention will be described with reference to the drawings.
Fig.5 (a) is a front view which shows the 1st modification of the dust wiping aid used for the dust collector in Embodiment 1 of this invention, FIG.5 (b) is in Embodiment 1 of this invention. It is a front view which shows the 2nd modification of the dust wiping aid used for a dust collector, FIG.5 (c) is the 3rd modification of the dust wiping aid used for the dust collector in Embodiment 1 of this invention. It is a front view which shows an example, FIG.5 (d) is a front view which shows the 4th modification of the dust removal tool used for the dust collector in Embodiment 1 of this invention.
In FIG. 5 (a), the dust removal aid 5a in the first modification is different from the dust removal aid 5 in the first embodiment in that the upper contraction portion 6 and the lower contraction portion 7b are not vertically symmetrical. The curvature of the top portion 7a ′ of the lower end contraction portion 7b is smaller than the curvature of the top portion 6a of the upper end contraction portion 6 and is formed in an arc shape.
In FIG.5 (b), the point from which the dust removal aid 5b in the 2nd modification differs from the dust removal aid 5 in Embodiment 1 is that the lower end contraction part 7c is formed in hemisphere. is there.
In FIG. 5C, the dust removal aid 5c in the third modified example is different from the dust removal aid 5 in the first embodiment in that a cylindrical cylinder is provided between the upper contraction portion 6 and the lower contraction portion 7. The point is that the part 8 is not formed.
In FIG. 5 (d), the dust removal aid 5d in the fourth modified example is different from the dust removal aid 5 in the first embodiment in that the upper contraction portion 6b and the lower contraction portion 7d are each in an octagonal pyramid shape. In other words, an octagonal prism body 8a is formed between the upper contraction part 6b and the lower contraction part 7d.

  As described above, in the present embodiment, the conical, elliptical hemispherical, hemispherical lower end contraction portion 7 (7b, 7c) is combined with the conical upper end contraction portion 6 and the octagonal pyramid upper end contraction portion. Although what combined 6b and the lower-end shrinkage | contraction part 7d was demonstrated, the shape of the dust wiping aid is not limited to these combinations. In addition to the conical shape, the upper contraction portion 6 may be an elliptical hemisphere, a hemisphere, a cannonball, a polygonal pyramid shape other than an octagonal pyramid. A shape such as a polygonal pyramid may be used. In particular, when the dust wiping aid is formed of an axially symmetric rotating body as shown in FIG. 1 and FIGS. 5A to 5C, the pressure distribution and the flow of air flow are uniform over the entire circumference. It is preferable because filtration can be efficiently performed on the entire surface of the bag filter 10 without unevenness.

As mentioned above, since the dust collector in Embodiment 1 of this invention is comprised, the following effects are acquired.
(1) Since the upper end contraction portion 6 formed by contracting toward the upper end is formed at the upper end portion in the longitudinal direction of the dust wiping aid 5, the nozzle 2 a disposed at the upper portion of the bag filter 10 during backwashing. When the compressed air is injected, a part of the compressed air is reflected in the radial direction (outer peripheral direction) of the bag filter 10 so as to be reflected by the inclined surface of the upper end contraction portion 6. The bag filter 10 can be blown outward substantially uniformly over the entire length from the upper end side to the lower end side of the bag filter 10, and the dust adhering to the outer surface of the bag filter 10 can be surely removed. It is excellent in the reliability of maintenance, and can improve the dust collection efficiency by expanding the effective filtration area at the time of dust collection.
(2) The dust removal assisting tool 5 can surely remove the dust adhering to the upper end side of the bag filter 10, prevents dust from accumulating, prevents the generation of dust bridges, and corrodes the partition plate 3. Can be prevented, and the dust collector has a long service life.
(3) Since the tubular body 4 into which the dust wiping aid 5 is inserted protrudes from the upper surface side of the partition plate 3 on which the bag filter 10 is disposed, the existing bag filter 10 is used as it is. It can be used by attaching it to the dust collector, improving the dust collection efficiency without modification, and is excellent in handling.
(4) When the dust wiping aid 5 is inserted into the tubular body 4 disposed above the bag filter 10, the flow path cross-sectional area formed on the outer periphery of the dust wiping aid 5 is changed to a conventional venturi. Compared to the mold, it can be expanded, the load of the blower used for suction during dust collection can be greatly reduced, and energy saving is excellent.
(5) Since the lower end contraction part 7 formed by shrinking toward the lower end is formed at the lower end part in the longitudinal direction of the dust wiping aid 5, the filtered clean air flow is sucked by the blower at the time of dust collection. It can be smoothly moved to the upstream side along the inclined surface of the lower end contraction portion 7, has little pressure loss, and is excellent in suction efficiency.
(6) The compressed air injected at the time of backwashing can be rectified by the lower end contraction portion 7, and the compressed air easily reaches the lower end side of the bag filter 10, and the dust adhering to the surface of the bag filter 10 is spread over the entire length. Efficient payments can be made.
(7) Since the upper end contraction portions 6 and 6b of the dust wiping aids 5 to 5d are formed in a conical shape or a polygonal pyramid shape, the compressed air injected at the time of backwashing is compressed at the center (axis From the center) toward the outer periphery, and the upper end of the bag filter 10 can be surely inflated outward over the entire periphery, so that dust can be efficiently removed. it can.
(8) Since the lower end contraction portions 7 and 7b to 7d of the dust wiping aids 5 to 5d are respectively formed in a conical shape, an elliptical hemispherical shape, a hemispherical shape, and a polygonal pyramid shape, they are sucked during dust collection The clean airflow can be moved to the upstream side along the entire circumference of the lower end contraction portions 7 and 7b to 7d, the load on the blower can be reduced, and energy saving is excellent.
(9) Since the bag filter 10 is a chrysanthemum shaped filter, the filtration area per unit volume can be greatly increased as compared with a cylindrical filter. 1 can be reduced in size and is excellent in space-saving property.

(Embodiment 2)
FIG. 6 is a cross-sectional front view of an essential part of the dust collector according to Embodiment 2 of the present invention. In addition, the same thing as Embodiment 1 attaches | subjects the same code | symbol, and abbreviate | omits description.
In FIG. 6, the dust collector 1a in the second embodiment is different from the first embodiment in that the total length of the dust wiping aid 5 (= x ₁ + x ₂ + y _{1) is} within the range of the length l ₂ of the tubular body 4 ′. ) And the dust removal tool 5 is disposed radially on the outer periphery of the cylindrical body 8 in the radial direction of the tubular body 4 ′ and welded to the inner wall of the tubular body 4 ′. The bag filter 20 is a cylindrical filter having a retainer 21 and a cylindrical filter cloth 20a covered on the outer periphery of the retainer 21.
In FIG. 6, 22 is a ring formed of a metal wire made of stainless steel or the like, and a plurality of retainer 21 fixing rings are arranged at predetermined intervals, and 23 is a metal wire made of stainless steel or the like and is formed on the outer peripheral side of the fixing ring 22 A plurality of vertical wires of the retainer 21 joined on the circumference of the retainer 21 by spot welding or the like, 24 is a bottom cover disposed at the lower end portion of the retainer 21, and 25 is a filter cloth fixing disposed at the upper end portion of the retainer 21. Part, 25a is a convex strip formed on the inner peripheral side of the filter cloth fixing part 25, 26 is formed in a substantially cylindrical shape, a bag filter fixing member for fixing the bag filter 20 to the opening 3a of the partition plate 3, 26 a is a recess formed on the outer periphery of the lower end of the bag filter fixing member 26 and sandwiches the upper end of the filter cloth 20 a together with the protrusion 25 a of the filter cloth fixing unit 25, and 26 b is on the outer periphery of the upper end of the bag filter fixing member 26. Formed partition board Fitting concave portion to be fitted and fixed in the opening 3a of the, 27 is a fixing band for fixing the upper end of the filter cloth 20a on the filter cloth fixing unit 25.
Accordingly, the dust collector 1a and the bag filter 20 can be easily attached and detached, and the bag filter 20 can be easily replaced without being caught by the dust wiping aid 5 when the bag filter 20 is taken in and out from the side. Can be performed, and is excellent in maintainability.
In the present embodiment, the dust removal aid 5 is used, but any of the dust removal aids 5a to 5d described in the first embodiment may be used.

  Since the usage method of the dust collector in Embodiment 2 of this invention comprised as mentioned above is the same as that of Embodiment 1, description is abbreviate | omitted.

  As mentioned above, since the dust collector in Embodiment 2 of this invention is comprised, the effect | action similar to Embodiment 1 is acquired.

The present invention provides a dust wiping aid that is inserted into the cylindrical body on the upper surface of the partition plate on which the bag filter is disposed, so that the nozzle is sprayed from the nozzle above the bag filter when the bag filter is backwashed. A part of the compressed air that is generated can be dispersed in the radial direction of the bag filter and sprayed directly on the upper end side of the bag filter. From the upper end side to the lower end side of the bag filter, the bag filter is inflated outward and adhered to the outer surface. Can be surely removed, and the cross-sectional area of the flow path at the upper end of the bag filter can be expanded compared to the conventional venturi type, greatly increasing the load on the blower used for suction during dust collection. Can reduce the effective filtration area during dust collection, improve dust collection efficiency, provide a dust collector with excellent energy saving, and filter existing bag filters. To improve efficiency and can contribute resource saving and energy saving.

Cross-sectional front view of main parts of the dust collector in Embodiment 1 of the present invention The principal part model perspective view which shows the attachment state of the bag filter to the support plate of the dust collector in Embodiment 1 of this invention The principal part cross-sectional front view which shows the attachment state of the dust wiping aid used for the dust collector in Embodiment 1 of this invention (A) Main part schematic sectional view showing the state of the bag filter during dust collection of the dust collector in Embodiment 1 of the present invention (b) The state of the bag filter during backwashing of the dust collector in Embodiment 1 of the present invention Schematic cross-sectional view of relevant parts (A) The front view which shows the 1st modification of the dust wiping aid used for the dust collector in Embodiment 1 of this invention (b) The dust wiping aid used for the dust collector in Embodiment 1 of this invention The front view which shows the 2nd modification of (c) The front view which shows the 3rd modification of the dust removal aid used for the dust collector in Embodiment 1 of this invention (d) Embodiment 1 of this invention View showing a fourth modification of the dust wiping aid used in the dust collector in Cross-sectional front view of main parts of the dust collector in Embodiment 2 of the present invention (A) Schematic sectional view showing the state of a bag filter during dust collection in a conventional dust collector equipped with a pulse jet type dust removal mechanism (b) Dust in a conventional dust collector equipped with a pulse jet type dust removal mechanism Schematic cross-sectional view of the main part showing the state of the bag filter when paying off (backwashing)

Explanation of symbols

1, 1a Dust collector 2 Draw-off mechanism 2a Nozzle 3 Partition plate (cell plate)
3a Opening part 3b Fixing tool 4, 4 'Tubular body 4a Lower flange 4b Upper flange 5, 5a, 5b, 5c, 5d Dust wiping aid 6, 6b Upper contraction part 6a, 7a, 7a' Top part 7, 7b, 7c 7d Lower end contraction part 8 Cylindrical body part 8a Rectangular column body part 9, 9A Fixing member 9a Hanging part 9b Extension part 10, 20 Bag filter 10a Filter body 11 Flange part 11a Seal part 11b, 24 Bottom cover 12 Support plate 20a Filter Cloth 21 Retainer 22 Fixing ring 23 Vertical wire 25 Filter cloth fixing part 25a Projecting line part 26 Bag filter fixing member 26a Concave line part 26b Fitting concave part 27 Fixed band 50 Bag filter 51 Retainer 52 Venturi pipe 52a Flange part 55 Filter cloth 60 Partition plate (cell plate)
70 Dispensing mechanism 70a Nozzle

Claims (4)

A dust collector that performs filtration by sucking with a blower from the upper end side of the bag filter and injecting compressed air from the nozzle disposed above the bag filter to the lower end side of the bag filter to thereby wash the bag filter. Because
A partition plate having a plurality of openings in which the bag filter is disposed, a tubular body projecting from the upper surface of the partition plate corresponding to the position of each opening, and an upper end at the upper end in the longitudinal direction A dust collector comprising: a dust wiping aid having an upper end shrinkage portion formed by being shrunk toward the tube and disposed in the tubular body.   The dust collector according to claim 1, wherein the dust wiping aid includes a lower end contraction portion formed by contracting toward a lower end at a lower end portion in a longitudinal direction.   The upper end contraction part or the lower end contraction part is formed in any one of a conical shape, a hemispherical shape, an elliptical hemispherical shape, a bullet shape, a spherical shape, and a polygonal pyramid shape. Or the dust collector of 2.   4. The bag filter according to claim 1, further comprising a cylindrical filter having a chrysanthemum-shaped molded filter or retainer and a filter cloth covering the outer periphery of the retainer. Dust collector.

Images