Laundry drying apparatus
[ 51 Apr. 29, 1975 United States Patent [191 Gerstenberger et al.  
  70 8766 ll ll l l. 00 800 3000000 33 331 Lauderdale. Fla.  
 July 3, 1974 Primary Examiner-George V Larkin [22] Filed:  
 Attorney Agent, or Firm-Oltman and Flynn 21 Appl. No.: 485,366  
 {57] ABSTRACT A laundry drying apparatus having an oil-heated Related U.S. Application Data Continuation-impart of Ser. No. 390,580. Aug. 22  
 I973. abandoned platen that is convex upwardly and across which laundry articles are advanced from an entrance end to an Field of Search....i.........................  
 38/l5-l7 56. 66; [00/153 ducting hot oil from its exit end to its entrance end.  
 Conveyors directly below the platen receive the laun- References Cited dry articles coming off the platen and these conveyors UNITED STATES PATENTS are heated by oil inlet and outlet pipes for the platen.  
 234.631 Vandercur 38/8 5 Claims. 6 Drawing Figures PATENTEBMRZQ I975 saw u o 5 1 LAUNDRY DRYING APPARATUS CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of our copending U.S. Pat. application, Ser. No. 390,580, filed Aug. 22, 1973, entitled Laundry Treating Apparatus now abandoned.  
 BACKGROUND OF THE INVENTION In a commercial or institutional laundry equipment, the laundry flatwork coming out of the ironer usually contains an excess of moisture that should be removed before the flatwork is folded.  
  Prior to the present invention, such moisture removal usually has been performed by passing the laundry pieces across a steam-heated platen. The steam heating of such moisture-removing platens has had many practical limitations and disadvantages. The platen was slow to heat up, and it could be heated only to a temperature of around 212F. This relatively low platen temperature imposed a limitation on the speed at which laundry flatwork could be moved across it and still achieve the desired moisture removal, as well as requiring that the platen itself be relatively long so that the incoming flat-- work would be subjected long enough to its limited heating effect. The water used as the steam source had to be replaced continuously and in most localities had to be treated to remove minerals. Even with such treatment of the water, scale removal was required at relatively frequent intervals in order to avoid clogging of the steam pipes. In most cases, the steam equipment required a stationary engineer to be in continuous attendance to insure that the relatively complicated steam equipment was operating safely and properly.  
  U.S. Pat. No. 2,375,426 to Manley discloses an arrangement for using hot oil in a laundry flat work ironer, U.S. Pat. No. 2,430,52l to Sando and U.S. Pat. No. 3,066,430 show the use of hot oil pressing machines, and U.S. Pat. No. 2,004,430 to Etten discloses using heated diethylene glycol in an ironing machine, all for the purpose of taking advantage of the higher temperatures possible with such fluids as compared with steam.  
 SUMMARY OF THE INVENTION The present invention is directed to a novel laundry drying, apparatus having an upwardly facing convex platen heated by oil or other suitable high boiling point fluid. The platen is convex from the end where the laundry article enters onto the platen over to the opposite end where the laundry article moves off the platen. An endless flexible belt conveyor closely overlies the convex top surface of the platen to advance the laundry article across it at a speed which is substantially faster than would be practical with a steam heated platen intended to provide equivalent moisture removal from the laundry article, because of the higher temperature at which the present platen is operated. A long, serpentine passageway in the platen conducts hot oil from its exit end to its entrance end. One or more conveyors extend directly beneath the platen for receiving the laundry article coming off the platen at its exit end. The inlet and outlet pipes which conduct heated fluid to and from the serpentine passageway in the platen extend in close proximity to these conveyors so as to enhance the drying of the laundry articles after they come off the platen and while they are on these conveyors.  
  It is a principal object of this invention to provide a novel and improved laundry drying apparatus or ironing apparatus having a fluidheated platen for removing moisture from laundry articles.  
  Another object of this invention is to provide such an apparatus in which the platen has a novel heating arrangementfor optimum removal of moisture from a laundry article that is advanced across the platen.  
  Another object of this invention is to provide an apparatus as just mentioned in which heated fluid is conducted through along serpentine path in the platen that progresses along the platen counter to the direction in which a laundry article is advanced along the platen.  
  Another object of this invention is to provide a novel and improved laundry drying apparatus having a fluidheated platen with a convex top surface, and a flexible endless belt conveyor closely overlying the top surface of the platen for advancing a laundry article while hold ing it down on the top surface of the platen along its convex length.  
  Another object of this invention is to provide a novel and improved laundry drying apparatus having a conveyor located under a fluid-heated platen and receiving the laundry articles from the platen, which conveyor is heated by the fluid inlet and outlet pipes for the platen to additionally remove moisture from the laundry articles.  
  Further objects and advantages of this invention will be apparent from the following detailed description of a presently preferred embodiment thereof, which is shown in the accompanying drawings, in which:  
  FIG. I is a side elevational view of the present apparatus, with the front of its housing broken away and with certain parts simplified for clarity;  
  FIG. 2 is a central vertical cross-section taken along the line 2-2 in FIG. I and broken at the middle.  
  FIG. 3 is a top plan view of the apparatus with parts broken away for clarity;  
  FIG. 4 is a vertical longitudinal section taken along the line 4-4 in FIG. 3 just behind the front wall of the apparatus;  
  FIG. 5 is a top perspective view showing the oilheated platen and the conveyor beneath it in this apparatus; and  
  FIG. 6 is a schematic diagram showing the hot oil circulation system in the present apparatus.  
  Before explaining the disclosed embodiment of the present invention in detail, it is to be understood that the invention is not limited in its application to the details of the particular arrangement shown, since the invention is capable of other embodiments. Also, the terminology used herein is for the purpose of description and not of limitation.  
  Referring first to FIG. 4, the present apparatus comprises an elongated, upwardly convex, heated platen l0 and conveyors for advancing a laundry article, such as a bed sheet, from right to left across the curved top of this platen and then carrying the article away from the platen.  
  An endless flexible belt conveyor II has its upper course or run extending up at an acute angle from right to left up to the left edge of the platen I0, and then it passes down around an upper roller 12 located beneath this end of the platen and then back to a lower roller 13. An idler roller 14 overlies the upper course of the inlet conveyor 11 midway between rollers 13 and 12 and it holds the laundry article A down on this conveyor.  
  An elongated, flexible, endless belt, second conveyor 15 overlies the platen along its entire convexly curved length. The lower course or run of this conveyor continuously overlies the convex top surface of the platen and it moves from right to left in FIG. 4 so as to hold the laundry article A down on the platen while advancing the laundry article from right to left across the top of the platen. In many cases the laundry article will have considerable moisture which adds to its weight and enhances the effect of gravity in holding the laundry article down on the platen as it moves along the convex length of the platen. The weight of the laundry article is sustained entirely by the rigid platen, and the overlying conveyor belts are required only to hold the laundry article down against the top surface of the platen while advancing the laundry article along the platen, but not to carry the weight of the laundry article.  
  The belts of the overlying conveyor 15 pass down around a roller 16 which overlies the roller 12 at the right end of the platen and after passing over the entire convex length of the platen these conveyor belts pass up around a roller 17 which overlies the left end edge of the platen. From here the conveyor belts pass successively over rollers l8, I9, 20 and 2l through a return course or run spaced above the platen and back to the roller l6.  
  A short flexible, endless belt, transfer conveyor 22 is located below the left end of the platen It) to receive the laundry article A as it moves down off this end of the platen. The belts of this conveyor are advanced counterclockwise in FIG. 4, passing down around an upper roller 23 and then vertically down to a lower roller 24 and then up around the lower roller and back up to the upper roller.  
  A longer, flexible endless belt conveyor 25 passes clockwise down around an upper roller 26, which is located to the left of roller 23 and slightly above it. At their respective upper rollers 23 and 26, the belts of the respective conveyors 22 and 25 are spaced apart enough to freely receive the laundry article between them and then they pass down in close confronting relationship to grip the laundry article between them. The belts of conveyor 25 pass down under roller 24 and then horizontally to the right beneath the platen 10 for almost the entire length of the platen. The conveyor belts 25 then pass down around a roller 27 located below and slightly to the left of the right end edge of the platen, and then they pass in a lower return run horizontally to the left over to a lower roller 28 and then up around this roller to the upper roller 26. The lower return run of conveyor 25 is spaced a short distance below its upper run.  
  A flexible endless belt lower conveyor 29 has a horizontal upper course or run extending immediately below the lower return run of conveyor 25 so as to receive the laundry article as it passes down around roller 27 and to convey it horizontally from right to left in FIG. 4. The belts of conveyor 29 pass counterclockwise up around a right end roller 30, then horizontally to the left and down around a left end roller 31, before retuming through a lower return run to the right. A curved guide plate 32 is positioned a short distance to the right of the roller 27 and above the right end roller 30 to guide the laundry article onto the conveyor 29 as it passes down around roller 27.  
  The laundry article A passes down around the left end roller 31 of the lower conveyor 29 into a suitable folding apparatus below (not shown).  
  The several conveyors are driven continuously from a suitable electric motor (not shown) which is arranged to advance the inlet conveyor 11 counterclockwise, the upper conveyor 15 clockwise, the short transfer conveyor 22 counterclockwise, the elongated conveyor 25 clockwise, and the lower conveyor 29 counterclockwise in FIG. 4.  
  In accordance with the preferred embodiment of the present invention, the platen l0 and the conveyors 25 and 29 beneath it are oil-heated to remove moisture from the laundry article as it is advanced through the apparatus.  
  Referring to FIG. 5, the heated oil flows through an inlet pipe having a vertical section 32, located behind the platen I0, and a horizontal section 33, extending from front to back beneath the platen and between the upper and lower courses of the conveyor 25, as best seen in FIG. 4. At the front of the apparatus the inlet pipe has an upwardly inclined section 34 extending up and to the left from the front end of the horizontal section 33 of the inlet pipe over to the front of the platen close to its left end edge which is the exit end of the platen for the laundry articles being advanced across the convex top surface of the platen.  
  The heated oil flows through internal passages in the platen 10, as explained in detail hereinafter, and it flows out of the platen at the front near the right end edge (which is the entrance end for the laundry articles) into a downwardly inclined section 35 of an outlet pipe. The lower end of this pipe section is located to the left of its upper end, and it is connected to the front end of a horizontal section 36 of the outlet pipe which passes from front to back beneath the platen l0 and between the upper and lower courses of the conveyor 25. The back end of this horizontal section of the outlet pipe is connected to the lower end of a vertical section 37 of this pipe, which extends up in back of the platen.  
  The inlet pipe 32 and the outlet pipe 37 for conducting heated oil to and from the platen 10 are part of a circulation system shown schematically in FIG. 6 and described in detail hereinafter with reference to that Figure.  
  The platen 10 presents a long serpentine internal passageway for conducting the heated oil from the inlet pipe 32-34 back and forth from front to back across the platen in succession from left to right along the convex length of the platen over to the outlet pipe 35-37.  
  Referring to FIG. 3, this passageway includes a pair of inlet tubes 40 and 41 positioned closely adjacent each other from left to right and joined integrally together to present at the front of the platen a common inlet chamber to which the inlet pipe 32-34 is connected. At the back of the platen both inlet tubes 40 and 4] are connected integrally to each other and to the back end of a third tube 42, which extends horizontally forward to the front of the platen, where it is joined integrally to a fourth tube 43. Successive horizontal tubes 44-56 are interconnected in alternate sequence at the back and front of the platen to conduct heated oil from front-to-back and back-to-front in succession along the platen from left to right in the drawings. These successive tubes are each oblong in crosssection, being substantially wider horizontally then vertically, and they are closely spaced from each other along the convex length of the platen and are disposed immediately below the top of the platen, as shown in FIG. 5, so that the top of the platen is heated very effectively across its entire extent from front to back and along its convex extent from left to right in the drawings. The heated oil passes out of the last pipe 56 at the right end of the platen and into the outlet pipe section at the front of the platen.  
  It will be noted that the tubing -56 under the top of the platen provides an extremely long serpentine path for the heated oil to maximize the time during which heat transfer is taking place from the oil to the top of the platen. The heat gradient provided by this tubing arrangement is opposite to the direction of movement of the laundry article across the platen. That is, the oil is hottest at the left end of the platen, which is the exit end for the laundry article, and the oil temperature gradually decreases as it flows in serpentine fashion to the right end of the platen, which is the entrance for the laundry article. With this arrangement, the temperature of the platen increases gradually along its convex length from the entrance end for the laundry article (the right end) over to the exit end for the laundry article (the left end), which is believed to provide the most effective removal of moisture from the laundry articles conveyed along the top of the platen.  
  As the laundry article is advanced along the convex length of the platen its weight is sustained by the platen itself, and the overlying conveyor belts l5 merely hold it down against the platen to advance it along the platen and at the same time assist in providing an ironing effect for removing wrinkles from the laundry article.  
  In addition to heating the laundry article on the platen, the heated oil also heats the laundry article A while it is on the conveyors 25 and 29 below the platen because of the close proximity to these conveyors of the horizontal sections 33 and 36 of the oil inlet and outlet pipes.  
  The oil supply and heating system, as shown schematically in FIG. 6, includes a suitable expansion tank provided with a vent 51 at the top and an oil level switch, shown schematically at 52. An expansion line 53 extends from the bottom of the tank 50 to a line 54, which is connected through a manual shutoff valve 55 and an expansion jont 56 to the inlet of a pump 57.  
  A system fill opening 58 is connected through a manual shutoff valve 59 to:  
 lv a manual shutoff valve 60 connected to line 54 at the inlet side of valve 55; and  
 2. through a filter 61 and a manual shutoff valve 62 to the outlet side of valve 55.  
  The outlet of the pump 57 is connected through an expansion joint 63 and a manual shutoff valve 64 to the inlet side of a heater 65. A thermometer 66 senses the oil temperature at the inlet side of valve 64. The oil is heated in the heater and then passes through a manual shutoff valve 67 to a main header 68. A thermometer 69 senses the oil temperature at the left end of the header 68 in FIG. 6.  
  The heated oil flows through a flow switch 70 and a manual shutoff valve 71 in the main header and then through an expansion joint 72 and a manual shutoff valve 73 to the previously mentioned inlet pipe 32-34 leaading into the tubing 40-56 in the platen 10. A thermometer 74 senses the oil temperature in this inlet pipe.  
  The heated oil coming out of the platen l0 flows through the previously mentioned outlet pipe 35-37 and through a manual shutoff valve 75 to a return line 76, which is connected through a manual shutoff valve 77 to line 54. A thermometer 78 senses the oil temperature in the outlet pipe 35-37.  
  A bypass valve 79 and an expansion joint 80 are connected in series with each other between the main header 68 and the return line 76.  
  A purging line 81 extends from the top of the expansion tank 50 through a manual shutoff valve 82 to the return line 76 at the inlet side of valve 77.  
  The heater 65 in this system heats the oil sufficiently to provide an oil temperature of at least 400F., and preferably 600F., at its entry into the tubing 40-56 in the platen.  
  The use of oil as the heating medium for the platen is advantageous in several respects over the steamheated platens previously used for the same general purpose. The oil can be heated to a temperature of 400F. or more, and preferably about 600F., and this allows the speed at which the conveyors operate to be substantially higher than would be possible with a steam-heated platen. In addition the length of the platen (from right to left in FIG. 1) may be substantially shorter than a steam-heated platen with an equivalent moisture removal effect.  
  Also, the use of oil instead of steam avoids the maintenance problems associated with steam traps and avoids the need for treatment of the water used as the steam source. Problems and maintenance procedures associated with the build-up of scale are entirely avoided, and it is not necessary to have an operating engineer in attendance. The heated oil system operates at much lower pressure than a steam system and it not subject to the regulations and standards applied to pressure vessels. The recirculated oil does not require replacement for a period of years, whereas the source water in conventional steam systems is not reused and therefore must be replenished continuously. Because of the relatively small volume of oil required, the present heated oil arrangement normally takes only about 10 minutes to reach a temperature of 400F. from a cold start, whereas a steam system often takes on the order of 30 minutes, after steam temperature is reached, to reach a much lower operating temperature of the platen.  
  The heater 65 in the present system has an inherently more efficient heat transfer relationship with the oil that it is heating than is possible of attainment in a steam generator, and consequently the fuel requirements for this heater are much lower than would be the case in a steam system of equivalent laundry-drying capacity. Also, if desired, the heated oil coming out of the platen may be used in making hot water or steam for other equipment in the laundry.  
 We claim:  
  1. In a laundry drying apparatus having a platen with a curved, convex, broad area top surface, and means for moving a laundry article across the top surface of said platen from an entrance end thereof to an opposite exit end, the improvement which comprises:  
 means for circulating heated fluid across said platen from said exit end to said entrance end in heat transfer relationship to its top surface to remove moisture from the laundry article moving across it, said platen having passage means therein for said heated fluid extending substantially completely across the platen directly below the top surface of the platen, said means for moving the laundry article across the platen comprising an endless flexible belt conveyor closely overlying the top surface of the platen from said entrance end to said exit end, and said top surface of the platen being convex in the direction along which the laundry article is moved across it. 2. In a laundry drying apparatus having a platen with a curved, convex. broad area top surface, and means for moving a laundry article across the top surface of said platen from an entrance end thereof to an opposite exit end, the improvement which comprises:  
  means including passage means for circulating heated fluid across said platenfrom said exit end to said entrance end in heat transfer relationship to its top surface to remove moisture from the laundry article moving across it, said passage means comprisng a serpentine passageway having interconnected passage segments extending back and forth across the platen substantially parallel to the axis of curvature of its top surface and arranged in close succession along the convex length of the platen from one end to the other, and further comprising means for introducing heated fluid into said passageway at the exit end of the platen and means for passing the heated fluid from said passageway at the entrance end of the platen. 3. A laundry drying apparatus according to claim 2 wherein said means for moving the laundry article across the platen is an endless flexible belt conveyor closely overlying the top surface of the platen from said entrance end to said exit end.  
  4. A laundry drying apparatus according to claim 3 and further comprising:  
 an endless flexible belt conveyor below said platen and having an upper run for conveying a laundry article coming off the exit end of the platen to a location beneath the entrance end of the platen, said conveyor having a lower return run extending below said upper run; an additional endless flexible belt conveyor below said first-mentioned conveyor and having an upper run immediately below said lower run of said firstmentioned conveyor for carrying the laundry article from said location beneath the entrance end of the platen to a discharge position beneath the exit end of the platen; and fluid inlet and outlet pipes connected respectively to the opposite ends of said passageway in the platen and extending transversely below the platen between the upper and lower runs of said first-mentioned conveyor for heating the laundry article on said conveyors 5. In a laundry drying apparatus having a platen with a curved, convex, broad area top surface, and means for moving a laundry article across the top surface of said platen from an entrance end thereof to an opposite exit end, the improvement which comprises:  
 means for circulating heated fluid across said platen from said exit end to said entrance end in heat transfer relationship to its top surface to remove moisture from the laundry article moving across it. said platen having fluid passage means therein for receiving said heated fluid, conveyor means below the platen for receiving the laundry article coming off the exit end of the platen, and fluid inlet and outlet pipes connected respectively to opposite ends of said passage means in the platen and extending in close proximity to said con veyor means for heating the laundry article thereon to additionally remove moisture from said laundry article.