Trapezoidal Painting Structure

This invention relates to a painting structures, such as spray painting booths and/or paint drying ovens, and more particularly to the cross-sectional arrangement for such structures.

Heretofore, painting structures, such as spray booths and/or paint drying ovens, have been built of a generally rectangular shape, with two opposite side walls generally parallel to each other. See FIG. 1. In some versions, the structures may have had inwardly and upwardly extending slanted portions, or gables, in the roof for accommodating light fixtures. See FIG. 2.

Examples of such prior art structures can be found in U.S. Pat. Nos. 4,096,066, 4,133,255, 4,173,924, 4,220,078, 4,222,319, 4,231,289, 4,241,646 and 4,292,056. These patents have complete side walls, or at least substantial portions thereof, which extended vertically or perpendicularly from the ground. As can be appreciated, the simple rectangular or square cross-sectional shape has the disadvantage of, if not heavily built, swaying or flexing, because a pair of parallel side walls set perpendicular to a parallel floor and roof lack inherent rigidity. To prevent such swaying or flexing, additional structural framing was necessary and provided. Of course, booths or ovens with gables in the roof are even more likely to sway or flex unless heavily built and/or strong structural framing is provided. Further, the gable construction necessitates additional, special panels forming the gables and reduces the number of standard size panels that are utilized to make the structure. Additionally, when the booth or oven is of a down draft construction, wherein air is supplied from the ceiling, the gables at the juncture of the roof and sides can create air spaces or pockets with air swirls therein which disrupt the generally desired downward air flow and/or can cause contaminants to collect on and/or blow onto the article being painted or upon which the paint is being baked or dried. Also, structures with gables on the roof are more expensive to build as they have more parts and more expensive to install because of the additional parts and extra work required to align the additional parts.

To overcome the foregoing disadvantages, a painting booth or oven structure of the present invention is provided without gables and with a trapezoidal, instead of the customary square or rectangular, cross-section.

In the preferred form the trapezoidal booth or oven structure of the present invention comprises a pair of straight, but inclined side walls that are spaced closer together at their tops than bottoms and a parallel floor and roof which connect the bottoms and tops of the inclined side walls together. Further, the roof is preferably provided with a full width air plenum which forms the ceiling of the paint spraying or drying space below.

The use of a roof shorter than the floor and the slanted or inclined, straight side walls joining the roof to the floor, inherently gives greater strength and rigidity. The booth or oven structure of the present invention is made up of fewer parts than a gabled design, can be easily standardized, and eliminates the need for extra structural framing. The structure of the present invention is less costly to manufacture and less costly to install as there are few pieces to make and align. The heretofore, costly to construct, and structurally weakening gables are eliminated. Additionally, not only is construction and installation less expensive, but the trapezoidal cross sectional structure provides superior and more uniform downward air flow from its ceiling plenum then would a structure with gables.

It is a primary object of the painting structure of the present invention to provide a cross-sectional shape or arrangement which is rigid and strong without the need for special structure framing.

Another object of the painting structure of the present invention is to reduce the cost of construction and of installation.

A further object of the painting structure of the present invention is to provide improved air flow, eliminating air pockets and/or air swirl that exists in prior art gabled structures.

These and other object of the present invention will become apparent from the following written description and accompanying drawings.

FIG. 1 is a cross-sectional view of one prior art painting structure of rectangular cross-section.

FIG. 2 is a cross-sectional view of a second prior art painting structure of a rectangular cross-section, but with gables.

FIG. 3 is a perspective view of the trapezoidal cross-sectional painting structure of the present invention.

FIG. 4 is a cross-sectional view of the structure shown in FIG. 3 taken along the line 4--4, but showing some alternative lighting arrangements.

FIG. 5 is a cross-sectional view of the structure of FIG. 3 showing the air flow.

Referring to FIGS. 1 and 2, prior art booths of either a rectangular or rectangular and gabled construction are shown. The prior art structures of FIGS. 1 and 2 have side walls 10 rising vertically from the floor 12 and joined to a roof 14. The roof and upper portions of the side walls may form an internal plenum 16, with a ceiling 18 therebelow made of a foraminous material closing off the plenum from the work space 19 below. As shown in FIG. 2, in the gabled version, the roof 14 and side walls 10 are joined by gables 24, which in this instance carry fluorescent light fixtures 26. These prior art booths were, of course, somewhat unstable and usually required additional support or framing (not shown) to prevent them from swaying or flexing. Of course, the gable construction of FIG. 2 was more complicated than the construction of FIG. 1 and was more expensive to make and install because of the extra parts and the need to align them.

The painting structure of the present invention, which could be utilized as, for example, a spray booth or oven, has a trapezoidal cross-sectional shape, instead of the prior art rectangular or rectangular-gabled construction. For purposes of illustration, and not by way of limitation, a paint spray booth structure 30 is shown in FIG. 3. The booth 30 comprises a pair of inclined or slanted walls 32 and 34 which are made up of standard sized panels 36 say 132" long and 36" wide with the tops inclined toward each other at an angle 6.degree. from vertical. While the angle of 6.degree. is used, any angle within a range of 5.degree. to 10.degree. would be acceptable. The side edges 38 of adjacent panels 36 are joined to each other by any convention construction known in the spray booth and/or oven arts. The sides 32 and 34 are joined to a roof 31 (FIG. 4) and a floor 33 to enclose the booth's work space 35. To locate the bottom of the side walls 32 and 34, the panel's bottom edges are set into channels 37 (FIG. 4) secured to the floor. The booth 30 could be of any size, and is shown large enough to accommodate an automotive vehicle for painting.

If desired, one or more, and in this case alternate panels have been fitted with windows 40, behind which (outside of the booth) a suitable light fixture 42 is arranged and located to shine through the window 40 to provide illumination for painting. Of course, other arrangements of light fixtures could be provided, or windows provided without any light fixtures However, the advantage of providing the light fixture with its long dimension vertical, as compared to horizontal, is that the light and window can be provided in the center of panel 36 without rendering the panel ineffective to carry vertical loads. Thus, for this reason the lighting arrangement of FIG. 3 is preferred.

If it were desired, the side walls 32 and/or 34 could be fitted with infrared heaters, (59A in FIG. 4) set in the wall in a manner similar to the lights. However, if quartz heaters are used, they would preferably be horizontal, rather than vertical (similar to 59), to optimize heater life. Rather than putting the heater tube behind a window, it would be closed off from the work space by a movable door to protect the heater when it is not is use. When horizontal openings are provided in the panels for such heaters or lights, the vertical edges of the panels can be reinforced with an extra strip of thicker sheet metal to help carry the load.

Of course, other size windows 44 could be provided in other panels 36. Further, if desired, a personnel door 46 can be provided in other of the panels 36. For ease of use and to make for easy opening and closing, the door frame for door 46 is completely vertical, and the surrounding area between the door frame and inclined side wall 32 of the booth is enclosed as indicated at 48.

To assist in entry and removal of the article to be painted, large doors, such as the conventional three part doors 50, 52 and 54 are provided on one or more ends of the booth. Again, for ease of opening the end wall 56 closing the booth is vertical so that the doors 50, 52 and 54 are also hung vertically. As shown the doors may be provided with windows 57. As is shown door 50 is hinged and hung to one side of the booth, and door 52 hinged and hung off of door 50, door 54 being hinged and hung off the other side of the booth. The other end of the booth could be closed by a similar door arrangement, be left open, and/or closed by a vertical or somewhat inclined wall.

Referring to FIG. 4, a cross section of the booth of FIG. 3 is shown. However, for purposes of illustration, other alternative lighting or infrared quartz heating systems are shown. Instead of having lighting as described in FIG. 3, the booth in FIG. 4 shows fluorescent fixtures 59 arranged horizontally, one side of the booth having two such fixtures and the other having but one. It is, of course, understood that windows are provided in the walls through which the lights may shine. The other side of this booth is also provided with two rows of parallel quartz infrared heaters 59A.

As is apparent from FIGS. 3 and 4, the booth 30 is of the down draft type and is provided with a floor opening 61 covered by a grill 63 to permit the withdrawal of the paint laden air from the booth. Such an opening could also be used to recirculate air for reheating in a hot air type oven configuration.

Further, FIG. 4 illustrates that a plenum 70 is formed by the tops of the two inclined sides 32 and 34 and the roof 31. The plenum is closed off from the roof 31, by a ceiling 72, which is preferably made of a foraminous filter material or cloth 74. The filter material 74 is carried in rectangular frame members 76 that, in this instance, are carried across one half the width of the booth. The frames 76 are pivoted at one end, in this instance the outer end as shown, so as to swing down, as indicated in the dotted lines 77, to facilitate changing the filter material when such is needed. However, preferably, the filter frame member could be pivoted 90.degree. from the position shown in FIG. 4 so that the pivot axis of the filter frame member is perpendicular to the booth's longitudinal axis, instead of parallel to that axis. To support the filter cloth, the frame member 76 is a rectangular frame having two side channels and two end channels, one of which is hinged from and the other is latchable in a horizontal position. Between the side channels a plurality of fixed battens or rods are provided, similar to the rungs on a ladder, to support the filter cloth in position. Instead of the filter frames being provided with spaced fix battens, the battens could be made removable and carried in pockets sewn or otherwise provided in the filter cloth material. A more complete description of such a filter cloth and batten arrangement is given in the copending George Allen, U.S. patent application No. 07/441,167, filed Nov. 27, 1989, entitled "Structure and Filter For Paint Spray Booth Or The Like" and filed on the same date as the present application.

The typical air flow through the down draft type booth 30 of the present invention is illustrated in FIG. 5. The air flow is generally uniform downwardly from the plenum 70 and filter-cloth ceiling, around the article or vehicle being painted and into the grill floor 63. The air swirls that formed in air pockets beneath the gables of prior art gabled booths are absent, thus providing a more desirable, more uniform air flow in the work space 35 and about the article.

While painting structure of the present invention was described for a spray booth, this concept could also be utilized for a paint drying or baking oven where suitable heating means such as infrared lamps, an air heater, or other heating means could be provided. Further, while a job shop type booth was illustrated and described, the present invention could also be utilized to produce a production, tunnel type booth and/or oven. Further, while the walls of the booth shown were simple panels, they could also be of a more complicated construction, such as double wall, double wall with insulation, particularly for an oven, or of bent construction to provide additional rigidity, as is well known in the art. For example, the ends of the panels could be bent at an angle to the panels to provide stiffening flanges, and then the respective flanges joined together by various fastening means, adhesives, or sheet metal clips. While the booth 30 shown is of a down draft construction, other type booths such as side draft could also utilize the present invention. While the preferred embodiment of trapezoidal booth of the present invention has been illustrated and described, from the foregoing it should be understood that variations, modifications and equivalent structures therefor fall within the scope of the appended claims.