WO2004024341A1

WO2004024341A1 - Filter apparatus for a powder coating spray booth

Info

Publication number: WO2004024341A1
Application number: PCT/US2003/027881
Authority: WO
Inventors: Donald L. Urg; Robert J. Allsop; Aron Curzon; Dan Belvedere; Glen Widdifield
Original assignee: Nordson Corporation
Priority date: 2002-09-10
Filing date: 2003-09-05
Publication date: 2004-03-25
Also published as: AU2003265951A1

Abstract

A filter apparatus for use with a powder spray booth includes an air flow chamber having an inlet opening and an outlet opening. The air flow chamber defines an air flow path extending through the air flow chamber between the inlet opening and the outlet opening. The inlet opening enables air to flow from a powder spray booth into the air flow chamber. A fan in the air flow chamber draws air from the booth through the inlet opening into the air flow chamber. A primary filter is disposed in the air flow path between the inlet opening and the fan. A final filter is disposed in the air flow path between the primary filter and the fan.

Description

Filter Apparatus for a Powder Coating Spray Booth

Technical Field

[0001] The present invention relates to a filter apparatus for use in association with a spray booth. In particular, the invention relates to a filter apparatus including a first filter and a final filter, for use in filtering air from a powder coating spray booth.

Background of the Invention

[0002] Powder coating of products is a known teclinique involving the spraying of powder coating material, having an electrostatic charge, on a workpiece that is electrically grounded. The powder coating material is attracted to and adheres to the workpiece to coat the workpiece.

[0003] Not all of the sprayed coating material adheres to the workpiece. Some of it drops to the floor of the spray booth. Some overspray is carried out of the spray booth in a stream of air that is drawn through the spray booth by an electric motor driven suction fan. This air is filtered before returning to atmosphere, to remove the coating material. The reclaimed coating material then is directed to the spray nozzle to be sprayed again.

[0004] The air is typically filtered by a primary filter, or first filter, located upstream of the suction fan. The primary filter typically does not remove all the coating material from the air that flows through it, and as a result there is still some coating material present in the air that flows through the fan. Therefore, a final filter is provided, downstream of the fan. The air drawn through the fan flows through the final filter and then is exhausted to atmosphere.

[0005] Because there is still some coating material present in the air that flows through the fan, some of the coating material also contacts the electric motor that drives the fan. This can adversely affect the operation and life of the electric motor. The coating material can also build up on the fan blades, adversely affecting operation of the fan.

Summary of the Invention

[0006] The present invention relates to a filter apparatus for use with a powder spray booth. The filter apparatus includes an air flow chamber having an inlet opening and an outlet opening. The air flow chamber defines an air flow path extending through the air flow chamber between the inlet opening and the outlet opening. The inlet opening enables air to flow from a powder spray booth into the air flow chamber. A fan in the air flow chamber draws air from the booth through the inlet, opening into the air flow chamber. A primary filter is disposed in the air flow path between the inlet opening and the fan. A final filter is disposed in the air flow path between the primary filter and the fan. The invention is applicable to filter apparatus in which the air flow through the final filter is horizontal, as well as in filter apparatus in which the air flow through the final filter is vertical.

Brief Description of the Drawings

[0007] The foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, in which: [0008] Fig. 1 is a schematic illustration of a filter apparatus in accordance with a first embodiment of the present invention, shown associated with a spray booth; [0009] Fig. 2 is an enlarged view showing a final filter that forms part of the filter apparatus of Fig. 1, being inserted into the filter apparatus; [0010] Fig. 3 is a schematic sectional view showing the final filter of Fig. 2 in place in the filter apparatus; and [0011] Fig. 4 is a view similar to Fig. 1 showing a filter apparatus in accordance with a second embodiment of the invention.

Detailed Description of the Invention

[0012] The present invention relates to a filter apparatus for use in association with a spray booth. In particular, the invention relates to a filter apparatus including a first filter and a final filter, for use in filtering air from a powder coating spray booth. As representative of the invention, Fig. 1 illustrates schematically a filter apparatus 10 in accordance with a first embodiment of the invention. The filter apparatus 10 is shown associated with a spray booth 12.

[0013] A workpiece 14 is suspended or otherwise positioned in the spray booth. A powder supply system 16 draws fresh powder coating material from a container 18 for coating the workpiece 14. The system 16 also draws powder coating material that is reclaimed from the filter apparatus 10, through a line 20.

[0014] The powder coating material from the supply system 16 is directed to the workpiece through a nozzle 22 that electrostatically charges the powder. The workpiece 14 is connected electrically to ground at 24. As a result, when the powder coating material sprayed from the nozzle 22 contacts the workpiece 14, the powder coating material is attracted to and adheres to the workpiece. In this manner, the workpiece 14 is coated.

[0015] The filter apparatus 10 includes a plurality of walls that define an air flow chamber 30. The plurality of walls include inlet walls 32 that define an inlet opening 34 of the chamber 30. The inlet opening 34 is in communication with the spray booth 12 for drawing air through the spray booth in a manner described below.

[0016] The filter apparatus 10 also includes outlet walls 36 that define an outlet opening 38 of the chamber 30. The outlet opening 38 is spaced apart from the inlet opening 34 and from the spray booth 12. The outlet opening 38 may be covered with a louvered exhaust panel as shown schematically at 40.

[0017] The filter apparatus 10 includes a fan 44. The fan 44 is located in the air flow chamber 32 between the inlet opening 34 and the outlet opening 38. The fan 44 may be supported on one or more fan support walls 46 in a manner not shown. The fan 44 is a suction fan driven by an electric motor 48. The fan 44 is adapted to draw air through the air flow chamber 30, in a direction from the inlet opening 34 to the outlet opening 38, along an air flow path.

[0018] The filter apparatus 10 includes a primary filter or first filter 52. The first filter 52 is located in the air flow path between the inlet opening 34 and the fan 44.

[0019] The first filter 52 is adapted to remove the majority of the powder from air flowing through the air flow chamber 30. In the embodiment of Fig. 1, the first filter 52 has a standard configuration for use in association with powder coating booths, including a plurality of hollow cylindrical cartridge filters 54 disposed in an array. Each one of the cartridges 54 has an open center into which air can flow radially through the filter material of the cartridge. The cartridges 54 are cleanable and replaceable as needed.

[0020] The filter apparatus 10 also includes a final filter 60. The final filter 60 is disposed in the air flow path 50 between the first filter 52 and the fan 44. The final filter 60 is not disposed between the fan 44 and the outlet opening 38. There are no filters between the final filter 60 and the outlet opening 38, and there are no filters between the fan 44 and the outlet opening 38. [0021] The final filter 60 is generally a known final filter for use in association with powder coating booths and, as shown schematically in the drawings, includes a filter element 62 (Figs. 2 and 3) mounted in a frame 64. The final filter 60 is adapted to remove the remaining powder from air flowing through the air flow chamber 30 downstream of the first filter 52. The final filter 60 also includes a seal 66 that is fixed to the frame 64 of the final filter.

[0022] The final filter 60 is mounted on filter support walls 68 of the chamber 30. The walls 68 include tracks 70 shown in Fig. 2. The filter 60 is mounted by sliding it into the tracks 70 in the direction shown by the arrows 72. When the filter 60 is mounted in the tracks 70, the seal 66 is captured between the frame 64 of the filter and the track 70. In other embodiments of the invention, the seal 66 may, alternatively, be provided on the wall that the final filter 60 is mounted on, rather than on the filter itself.

[0023] When the spray booth 12 is operated, the filtering apparatus 10 is operated also. The fan 44 creates a flow of air through the chamber 30, in a direction from the inlet opening 34 to the outlet opening 38. The air is drawn into and through the spray booth 12, through an opening shown schematically at 80. The air flowing through the spray booth 12 picks up powder overspray and carries it into the filter apparatus 10 through the inlet opening 34 of the filter apparatus.

[0024] The air flows through the first filter 52. In the first filter 52, most of the powder is removed from the air, but typically some remains. The air exits the first filter 52 and flows vertically to and through the final filter 60, as indicated by the arrows 82.

[0025] When the air flows through the final filter 60, substantially all the remaining powder is removed. The air leaving the final filter 60 is significantly cleaner than when it leaves the first filter 52.

[0026] The air that passes through the final filter 60 then flows vertically past and over the fan 44 and the motor 48. Because the air flowing past the fan 44 and motor 48 has been cleaned by the final filter 60 as well as by the first filter 52, the chance of any remaining powder adversely affecting the operation of the motor is minimal, as compared with air that has been cleaned only by the first filter. This reduction in powder can help to increase the reliability and life of the electric motor 48. [0027] In addition, because the air flowing past the fan 44 and motor 48 has been cleaned by the final filter 60 as well as the first filter 52, the chance of any remaining powder accumulating on the blades of the fan is minimal, as compared with air that has been cleaned only by the first filter. This reduction in powder can help to increase reliability and lessen needed maintenance requirements for the fan 44.

[0028] The air flowing through the final filter 60 exerts a significant force on the final filter, in the direction of air flow, as shown by the arrows in Fig. 3. This force causes the filter 60 to press the seal 66 against the track 70, helping to increase the effectiveness of the seal. This can help to contain more of the powder overspray in the filter apparatus 10, and also increase the effectiveness of the filter apparatus.

[0029] The effectiveness of the final filtering stage is also increased by the present invention. In the prior art system discussed above, the air that flows through the final filter is outlet air from a suction fan. In contrast, with the present invention, the fan 44, which is a suction fan, draws the air through the final filter 60. This creates better air flow through the final filter 60 and thus increases the effectiveness of the final filtering stage of the filter apparatus 10.

[0030] Fig. 4 is a view similar to Fig. 1 showing a filter apparatus 10a in accordance with a second embodiment of the invention. The filter apparatus 10a is similar to the filter apparatus 10 (Fig. 1) and parts of the filter apparatus 10a that are the same or similar are given the same reference numerals with the suffix "a" attached.

[0031] In the filter apparatus 10a, the portion of the air flow path that extends through the final filter 60a is oriented horizontally, rather than vertically. Thus, the air exiting the primary filter 52a flows horizontally (in a left to right direction as viewed in Fig. 4) into and through the final filter 60a. This air is then directed by the fan 44a to flow vertically to the outlet opening 38a. It can thus be seen that the present invention is applicable to filter arrangements with varying air flow paths and various orientations of the final filter.

[0032] From the foregoing description of the invention, those skilled in the art will perceive improvements, changes, and modifications in the invention. Such improvements, changes, and modifications within the skill of the art are intended to be included within the scope of the appended claims.

Claims

I claim:

1. A filter apparatus for use with a powder spray booth, comprising: an air flow chamber having an inlet opening and an outlet opening, said air flow chamber defining an air flow path extending through said air flow chamber between said inlet opening and said outlet opening, said inlet opening for enabling air to flow from a powder spray booth into said air flow chamber; a fan in said air flow chamber for drawing air from the booth through said inlet opening into said air flow chamber; a primary filter disposed in said air flow path between said inlet opening and said fan; and a final filter disposed in said air flow path between said primary filter and said fan.

2. A filter apparatus as set forth in claim 1 wherein said fan is a suction fan disposed in said air flow path between said final filter and said outlet opening.

3. A filter apparatus as set forth in claim 2 wherein said air flow path is free of filters between said final filter and said outlet opening.

4. A filter apparatus as set forth in claim 1 wherein said air flow path extends through said final filter in a generally vertical direction.

5. A filter apparatus as set forth in claim 1 wherein said air flow path extends through said final filter in a generally horizontal direction.

6. A filter apparatus as set forth in claim 1 comprising a wall at least partially defining said air flow chamber, the flow of air through said air flow chamber along said air flow path drawing said final filter into a sealed condition relative to said wall.

7. A filter apparatus as set forth in claim 6 comprising a seal between said wall and said final filter, the flow of air through said air flow chamber drawing said final filter into a position pressing said seal between said final filter and said wall.

8. A filter apparatus as set forth in claim 6 wherein said seal is fixed to said final filter.

9. A filter apparatus as set forth in claim 1 wherein said primary filter comprises a plurality of cylindrical filter cartridges disposed in an array in said air flow path whereby air flows radially inward into each one of said cylindrical filter cartridges and axially outward through an open center of each one of said cylindrical filter cartridges.