US 3738621 A
This disclosure relates to a rooftop evaporative cooler for cooling the interior of vehicles, such as campers and trailers, whether the vehicle is moving or stationary. The unit includes a rear-facing streamlined housing disposed over a rooftop register. The forward surface of the housing slopes upwardly from the vehicle roof to a horizontal rear portion adjacent a rear-opening, louvered entrance port. A suction fan is disposed within the housing between the entrance port and the register for pulling air into the housing through an evaporative pad and for expelling cooled air, guided by the configuration of the housing, through the register into the vehicle. The cooling medium is pumped from a supply tank contained within the housing to a distributor over the pad and collected after it passes through the pad for recirculation. The supply tank is substantially toroidal and is disposed within the lower portion of the housing, surrounding the rooftop register. The pad is constructed of a suitable porous material and the cooling medium is typically water.
Description (OCR text may contain errors)
United States Patent 1 Anderson EVAPORATIVE COOLER  Inventor: Les Anderson, Las Vegas, Nev.  Assignee: Everkool, Inc., Las Vegas, Nev.  Filed: Sept. 17, 1971  Appl. No.: 181,341
Related US. Application Data  Continuation-impart of Ser. No. 875,084, Nov. 10,
1969, Pat. No. 3,606,982.
UNITED STATES PATENTS 1,539,534 5/1925 Ansell 98/2 G 1,574,880 3/1926 Garland 2,075,389 3/1937 Eubank 62/259 RC 2,796,014 6/1957 Montgomery et al. 261/D1G. 4 2,977,774 4/1961 Ferris 62/212 2,998,714 9/1961 Bonzer 3,294,376 12/1966 Eranosian 3,352,353 Stevens et al 261/D1G. 4
l memz iziaw June 12, 1973 l/l97l Grasseler 26l/D1G. 4 6/1971 Logue 26l/DIG. 4
[ ABSTRACT This disclosure relates to a rooftop evaporative cooler for cooling the interior of vehicles, such as campers and trailers, whether the vehicle is moving or stationary. The unit includes a rear-facing streamlined housing disposed over a rooftop register. The forward surface of the housing slopes upwardly from the vehicle roof to a horizontal rear portion adjacent a rear-opening, louvered entrance port. A suction fan is disposed within the housing between the entrance port and the register for pulling air into the housing through an evaporative pad and for expelling cooled air, guided by the configuration of the housing, through the register into the vehi cle. The cooling medium is pumped from a supply tank contained within the housing to a distributor over the pad and collected after it passes through the pad for recirculation. The supply tank is substantially toroidal and is disposed within the lower portion of the housing, surrounding the rooftop register. The pad is constructed of a suitable porous material and the cooling medium is typically water.
14 Claims, 7 Drawing Figures PATENTED I 2 SHEEISHFS Flee EVAPORATIVE COOLER This application is a continuation-in-part of my copending patent application Ser. No. 875,084, filed Nov. 10, 1969, now US. Pat. No. 3,606,982.
Evaporative coolers depend upon the well-known principle that as a warm air stream passes in intimate contact with a body of water, heat is transferred from the air to the water as the water evaporates. This principle has found a variety of applications in humidifiers and large-scale air conditioning units.
Prior small-scale adaptations of this principle have encountered design difficulties because of the requirement that a large volume of air must pass in intimate contact with water over a large surface area to provide efficient cooling. This system requirement, however, must be met with a small-scale unit, the dimensions of which severely limit the type of system which may be employed.
Prior interior cooling devices for moving vehicles have utilized an evaporative pad disposed in an airscoop opening in the direction of movement. This device, a ram type, only cools when the vehicle is moving, and has several disadvantages. Insects and debris foul the entrance port, reducing the flow of air, and the design inherently creates vehicle drag. This drag requires a strong bracing system connecting the unit to the vehicle and the drag causes an increase in vehicle gasoline consumption.
Rearwardly opening units have been proposed, but such units have not been feasible. Although such units could be streamlined, the turbulence caused by air rushing over the unit resulted in a turbulent low pressure at the rear entrance port. In order to pull warm air into the system, a large suction fan was required. The size of the fan required when the vehicle was moving was grossly disproportionate to the size required when the vehicle was not moving because, in the latter instance, there was no turbulent low pressure at the entrance port. Therefore, these units were uneconomical and expensive.
Other rearwardly opening evaporative coolers have been of complicated construction or of limited special utility. One such unit is intended to be attached to the rear wall of a truck cab for cooling the interior sleeping area. This device utilizes a falling stream of water against a rising current of air which is filtered, cooled, dried, and subsequently blown into the cab adjacent the sleeping area. Such a device is not adaptable to relatively large vehicles, such as campers or trailers, since most efficient cooling requires air injection at the top thereof while the prior device is attached at the rear of the vehicle. This device could not practically be top mounted since it requires that warm air enter at the side of an elongated tubular structure and follow an upwardly directed Z-shaped path from the warm air inlet to the cool air outlet and into the cab.
As noted above, a universally adaptable cooling unit for relatively large vehicles wherein the available space is designed for either storage or living area ideally should be mounted on the roof. Rear mounting would, in most cases, necessitate a special arrangement of living and sleeping quarters to allow for circulation. Moreover, maximum. effective circulation of cool air without rearrangement of the existing living and sleeping areas is achieved with an overhead. unit.
The rear-mounted unit has another disadvantage similar to prior rear-opening, top-mounted units. A large enough fan is required while the vehicle is moving to suck in warm air from the turbulent low pressure trough following the vehicle. However, when the vehicle is at rest, and the unit is in use, a smaller fan would be adequate. Therefore, the use of the large fan would be unduly expensive if a cooler could be designed to use a smaller fan, even when the vehicle is in motion.
The device of the present invention broadly includes a streamlined housing having a rearwardly-opening, louvered entrance port and a downwardly-opening exit port. An evaporative pad is vertically mounted within the housing adjacent the entrance port, and a substantially toroidal coolant supply tank is mounted below the pad surrounding the exit port. A suction fan is also disposed within the housing between the pad and the exit port. Coolant is pumped from the tank, and is distributed over the upper surface of the pad. The coolant falls downwardly through the pad into a collection tray disposed below the pad. Coolant from the tray is then returned to the tank for recirculation.
In order to minimize the formation of an area of decreased pressure at the entrance port when the vehicle is in motion, the streamlined forward surface of the housing terminates in a horizontal roof portion adjacent the rear of the housing. The housing is preferable constructed of a reflective plastic material with a rib configuration for additional strength.
The shape of the housing permits efficient use of the device of this invention when the vehicle is moving. It has been discovered that by opening a window in the vehicle, a sufficient pressure differential is created to draw air through the entrance port and evaporative pad without the use of the fan. However, in the event it is not desired to open a window or when the vehicle is not moving, a small fan mounted between the entrance and exit ports will easily furnish a sufficient amount of air to cool the vehicle.
The device of this invention also utilizes a small electric pump for circulating the coolant. The pump and the fan should preferably be adapted to run separately or together on either direct current from a battery or alternating current. A volt source of alternating current is normally available at a campgroundand utilization thereof for operating the device of this invention when the vehicle is parked will avoid discharging the vehicle battery.
Accordingly, it is an object of this invention to pro vide a rear-opening, rooftop evaporative cooler for vehicles such as campers and house trailers.
It is another object to provide such a device with a streamlined external configuration to reduce vehicle drag, coupled with an upper surface configuration adjacent the entrance port designed to reduce the formation of a turbulent low pressure trough at the said port when the vehicle is moving.
It is still another object to provide a rooftop cooler which is equally efficient for moving or parked vehicles.
It is also another object to provide such a device which is compact and self-contained, and adapted to be used either coupled to the vehicle electrical system or to an independent source of alternating current.
It is another object to provide a compact and efficient rooftop cooler for vehicles having a recirculating coolant supply, the cooler being small, streamlined, and effective to cooleither. a moving or stationary vehicle.
It is another object to provide an evaporative rooftop cooler for moving or stationary vehicles using a falling stream of water through a porous pad, the pad being disposed across the stream of warm air entering the cooler, a portion of the flowing water evaporating to humidify and cool the air, and the remaining water being collected for recirculation for additional evaporative cooling.
It is a further object to provide an evaporative cooler wherein warm air is passed through a moisture-laden evaporative pad wherein it is cooled, humidified, and directed into the area to be cooled, the pad having a recirculating source of evaporative coolant from a storage tank disposed thereunder.
The exact nature of the invention, as well as other objects and advantages, will become readily apparent with reference to the following specification, claims, and appended drawings, wherein:
FIG. 1 is a perspective view of a vehicle with the evaporative coolerof this invention mounted on the roof;
FIG. 2 is a cross-sectional view taken along line 22 of FIG. 1;
FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2;
FIG. 4 is a fragmentary view in partial section taken along line 44 of FIG. 2;
FIG. 5 is a fragmentary view of the evaporative pad having a portion of the outer surface removed;
FIG. 6 is a rear elevation, partially broken away; and
FIG. 7 is a cross-sectional view taken along line 77 of FIG. 2.
With attention to the drawings, as shown in FIG. 1, the evaporative cooler 10 of this invention is intended to be mounted on the roof 12 of a vehicle, such as a camper, a trailer, or a boat. The cooler 10 is comprised of an outside housing 14 which may be formed of sheet metal or other suitable material, but preferably is formed of compounded high density polyethylene. The housing preferably has ribs 16 for extra strength. In the preferred construction, the housing is white in color and contains an ultra violet light inhibitor to enhance its reflective properties.
The housing is formed with a streamlined leading edge 18 which terminates in a flat roof section 20 adjacent the rear of housing 14. As shown in FIGS. 2 and 6, the cooler 10 also includes a rear-facing entrance port 22 through which warm air is drawn into the device. The port 22 may, in the preferred embodiment, have louvers 24 to shelter the interior of the cooler from the weather, and from insects and other foreign matter which might be sucked in through the entrance port 22.
It has been discovered that the flattened roof portion 20 on housing 14 functions to minimize the formation of a vacuum at the entrance port 22. When the vehicle is moving, the air stream passing over a streamlined surface and around hosing 14 would normally be expected to create a trough of turbulent low pressure at the rear of housing 14. However, by providing the flattened roof portion 20 immediately adjacent the rear of housing 14, the formation of this low pressure trough is minimized. Optimally the ratio of the overall length of cooler 10 to the length of area 20 should be about 6:1, or in a device about 3 feet long the length of the flattened roof portion 20 is preferred to be about 6 inches.
Louvers 24 are carried by a removable back plate 26. Plate 26 may be secured to housing 14 in any conventional manner, such as with screws, spring clips, or wing nuts (not shown) which may be attached to lateral brace 27 shown in FIG. 2. Removal of plate 26 provides access to the interior of the device.
Housing 14 also includes an integral base 28 having an exhaustport 30 therethrough. Cooled, humidified air from the cooler 10 enters the space to be cooled through the exhaust port 30. As shown in FIG. 2, the exhaust port 30 is intended to be mounted over a hole 32 in the roof 12 of the vehicle. The exhaust port 30 may be covered with a conventional louvered register 34, as shown in FIGS. 2 and 3, or a stepdown deflector (not shown) may be utilized. The cooler 10 may be mounted on the roof 12 of the vehicle by bracket 36 which attaches the base 28 of housing 14 to the vehicle roof 12. Alternatively, any conventional mounting device may be utilized, such as rivets or bolts, or if the base 20 is formed of metal, it may be welded to the roof of the vehicle if desired.
As previously noted, cooling is effected by passing a stream of air through a moisture-laden medium. According to this invention, the medium is comprised of a porous pad 38 disposed within housing 14 adjacent the entrance port 22, as shown in FIGS. 2, 3 and 6. The pad 38 may be made of several layers of cloth, of foamed molded plastic, or preferably of shreaded wood fibers, such as excelsior, retained in an open mesh plastic container 40, or other suitable material as shown in FIGS. 5 and 6. A metal or molded plastic frame 42 is provided to hold pad 38 and to simplify pad replacement when necessary. Pad 38 is retained in frame 42 by a convex metal grid 44 which is retained by the U- shape side portions 46 of frame 42 as shown in FIGS. 3 and 6. The rear plate 48 of frame 42 mounts internal louvers 50 which form splashplates as shown in FIGS. 2 and 7. Accordingly, grid 44 retains pad 38 against splashplates 50. When the pad 38 is moistened and warm air enters port 22 passing through pad 38, splashplates 50 act to prevent entrainment of drops of moisture from pad 38 in the air stream passing into cooler 10. Pad 38 may be replaced merely by removing back plate 26 and grid 44.
Warm air is sucked into cooler 10 through the entrance port 22 and through pad 38 by fan 60. The fan is surrounded by a shroud 62 and is mounted by bracket 64 to the said shroud as shown in FIG. 2. Shroud 62 includes mounting flanges 66 at the sides thereof as shown in FIG. 3. Flanges 66 may be secured to the side 68 of housing 14 in any conventional manner, such as by bolts, rivets, or by wing nuts. It will be obvious to those skilled in the art that the fan may be mounted in a variety of different ways. For example, a bracket (not shown) may be mounted on roof 12 through the hole 32 and connected to the lower surface of shroud 62 to provide added stability for the fan. Due to space requirements, the fan is mounted at approximately a 30 angle to the vertical.
Fan 60 may have either two or four blades 72 or the fan may be of the squirrel cage type, depending upon the volume of air to be moved. In the preferred embodiment, however, four blades 72 are provided, and the blades are mounted with a pitch of approximately 45. The fan 60 is preferably driven by a 6 or a 12 volt electric motor. The fan should be capable of moving between 200 and 800 cubic feet per minute (cfm) through the cooler, depending on the size of the vehicle to be cooled, and should be capable of operating at 1,500 or preferably up to about 1,650 revolutions per minute (rpm). The fan speed may also be controlled by a rheostat, if desired, and an AC/DC converter, shown generally at 74, may be provided. In this way, the fan may be driven by energy provided by the vehicle battery or, in the event an alternating current source is available, the unit may be converted to operate on alternating current. Therefore, when the vehicle is parked in a campground, the vehicle may be cooled by the device of this invention without discharging the vehicle battery. It has been found that the power requirement for fan 60 need not exceed about 6 amp. hours and preferably is about 3 to 3% amp. hours to provide adequate cooling for a standard camper or trailer.
A coolant 76, such as water, is fed by pump 78 from storage tank 80 to distributor 82 by line 84. Distributor 82 as shown in FIG. 7 is a seepage tube which is disposed over pad 38. A water tray 86 having slots 88 punched upwardly therethrough is mounted on the upper surface of frame 48. Water from distributor 82 collects in tray 86 and flows through'slots 88 and onto pad 38. The openings in tray 86 are preferably slots as shown in FIG. 4 to minimize clogging. The pad 38 rests on a mesh 90 supported by frame 48. Supply tank 80 mounts a trough 92, shown in FIGS. 2 and 4 which in turn supports frame 48 and mesh 90. As water from tray 86 seeps downwardly through pad 38 and through mesh 90, it collects in trough 92. Trough 92 is provided with drain holes 94 for returning the water collected therein to tank 80.
Tank 80 is substantially toroidal and preferably fills the lower portion of housing 18, surrounding the exit port 30. Tank 80 is intended to occupy the available space within the lower portion of housing 14 to maximize the storage capability of cooler 10. The tank 80 is preferably provided with an inlet 96 for filling and an outlet 98 for drainage.
The pad 38 is maintained in a saturated condition so that as warm air is drawn through port 22 and pad 38 by fan 60, it will cause the liquid water in the pad 38 to evaporate, cooling and humidifying the air with the vaporized water.
Coolant from tank 80 is conveyed to pad 38 by pump 78. Although a wide variety of pumps may be adapted for use with the device of this invention, a submerged centrifugal pump is preferred. The pump preferred for use with this invention is described and claimed in my copending application Ser. No. 163,400, filed July 16, 1971, which disclosure is hereby incorporated by reference. Briefly summarized, however, the pump is driven by an electric motor 100 mounted on a splashplate 102 which in turn is secured to tank 80. Water from the pump is drawn in through a filter in the lower surface thereof 104 and propelled by the impeller (not shown) through outlet 106 and line 84 to distributor 82. The pump is preferably constructed of reinforced plastic (with the exception of the motor) and is intended to maintain a capacity of about 0.5 gallons per minute. Although a greater flow rate of for example from 0.5 to 1.0 gallons per minute could be used to keep the pad 38 saturated, the greater flow rate will tend to cause water from the pad to be entrained in the air stream passing therethrough. The electric motor 100 preferably has an amp. hours power requirement of from I to 1% amps. The motor should also be adapted to be se- I lectively coupled to the AC/DC converter '74 or to the vehicle battery. In this way, the pump may be run without the fan, or both the pump and the fan may be run either by the vehicle battery, or by an independent source of alternating current.
It has been found that various engineering changes may be made within the scope of this invention. The type of fan and the type of pump employed are dictated by the volume of air to be cooled, which in turn will depend in part upon the size of the vehicle. It should be emphasized, however, that a pump having a capacity of approximately 0.5 gpm and a fan as described capable of operating from 1,500 rpm up to about 1,650 rpm will be adequate for campers, boats, and moderately large trailers. In tests employed with the device of this invention wherein the ambient atmospheric temperature was about 110 with humidity of about 30 percent, the device of this invention was capable of creating and maintaining a 30 temperature differential within a camper. The temperature was observed to drop from over down to the 70s within about one-half hour.
It should also be emphasized that the structural configuration of the housing will allow operation of the cooler of this invention without use of the fan when the vehicle is moving. By opening a window in the vehicle, and operating the pump, sufficient air will be sucked through the entrance port and through the saturated pad and subsequently into the camper to maintain a comfortable temperature therein. In the event it is desired to close the camper, operation of the fan and pump simultaneously when the vehicle is moving will not create an undue load on the vehicle electrical system. Moreover, when the vehicle is parked and a source of alternating current is available, the cooler may be operated for lengthy periods of time compatible with a standard volt circuit.
In addition to the features hereinbefore described, the tank may be provided with a sight gage (not shown) and an overflow port for the filling. It should be noted that in the preferred version of this invention wherein a submerged centrifugal pump is employed, the coolant level should not be allowed to drop below the pump inlet, and therefore use of a sight gauge may be desired.
In summary, an efficient, compact, and commercially satisfactory rooftop evaporative cooler for trailers, campers, boats, and other vehicles, has been described. Broadly, the cooler operates by drawing warm air through a liquid saturated pad and expelling the evaporation cooled air downwardly through a register into the vehicle. A substantially toroidal storage tank is disposed in the lower portion of the cooler with a submerged pump mounted thereon and a suction fan mounted thereover. The pump draws the liquid from the tank to a distributor over the pad to maintain the pad in a saturated condition. Coolant seeps downwardly through the pad to a collection trough mounted on the tank which collects the coolant and returns it to the tank for recirculation. The fan is disposed behind the pump and between the pad and the exit port. The
fan is designed to suck warm air through the pad, and expel the cooled air through the exit port into the vehicle. The cooler housing has a rear-facing entrance port to minimize clogging thereof with iitsects and debris, and to minimize drag. A streamlined design is further provided to minimize drag on the vehicle and the streamlined leading surface terminates in a horizontal roof portion to minimize the formation of a low pressure area at the rear opening of the entrance port.
The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. THe present embodiment is therefore intended to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
What is claimed and desired to be secured by United States Letters Patent is:
l. A rooftop evaporative cooler for a vehicle comprising: a streamlined hollow housing having a forward sloping surface, a rear opening entrance port, a flattened roof portion disposed between said forward sloping surface and said entrance port, and a downwardly opening exit port; said housing adapted to be mounted on the roof of a vehicle; a liquid saturable medium disposed within said enclosure adjacent said entrance port; fan means mounted within said enclosure for pulling warm air into the enclosure through the entrance port and said saturable medium and for expelling cooled air from said exit port into said vehicle; a substantially toroidal storage tank disposed within the lower portion of said housing beneath said medium and said fan means and surrounding said exit port; a submergible pump means mounted within said tank for continuously introducing evaporative coolant liquid into said medium to saturate the same; and means disposed below said medium and in communication with the interior of said tank for recovering unevaporated liquid coolant from said medium and for reintroducing said liquid coolant into said tank for recirculation.
2. The cooler of claim 1 wherein the said fan means is disposed between the entrance and exit ports, said exit port being adjacent the forward edge of said sloping surface so that said fan means cooperates with the internal surface of said streamlined housing to direct cooled air downwardly through said exit port.
3. The evaporative cooler of claim 1 wherein said evaporative coolant liquid is water and the warm air entering said entrance port is cooled and humidified as it passes through the saturated medium and a portion of the liquid vaporizes.
4. The cooler of claim 1 wherein said pump means comprising a pump having an inlet in communication with the interior of said tank and an outlet; distributing means disposed over said medium for distributing coolant liquid over the upper surface of said medium, said distributing means being in communication with the outlet of said pump so that liquid from said tank may be pumped through said distributing means, to the upper surface of said medium to seep downwardly therethrough.
5. The cooler of claim 4 wherein said distributing means comprises a foraminous seepage tube in communication with the outlet of said pump and disposed over said medium; a V-shaped tray disposed between said tube and said medium in longitudinal alignment therewith, said tray having a plurality of openings in a side thereof so that liquid from said tube will collect in said tray and pass through the openings therein onto the upper surface of said medium.
6. The cooler of claim 1 wherein said liquid saturable medium comprises: a frame having rigid sides and a foraminous base, a louvered back plate resting on said base and extending between said sides, the louvers on said plate extending downwardly and into the interior of said frame; a liquid saturable material disposed within said frame to occupy the interior thereof, said material supported by the foraminous base of said frame; an open mesh front retainer connecting said rigid sides, said retainer configured to urge said material against the louvers of said back plate.
7. The medium of claim 6 wherein said liquid saturable material is excelsior encased in a mesh container.
8. The medium of claim 6 wherein said retainer is a 'convex grid.
9. The cooler of claim 6 wherein said means for recovering liquid coolant comprises a tray mounted on said frame below the base thereof, said tray having a drain means in communication with the interior of said tank.
10. The cooler of claim 1 wherein the ratio of the overall length of said streamlined housing to the length of the flattened roof portion thereof is approximately 6:1.
11. The cooler of claim 1 wherein said fan means has the capacity of moving from 200 to 800 cubic feet of air per minute through said cooler and said pump has a capacity of about 0.5 gallons per minute.
12. The cooler of claim 11 wherein said fan and said pump are electrically powered and have a total power requirement of no more than about 7% amp-hours.
13. The cooler of claim 12 further comprising an AC/DC converter adapted to be selectively coupled between said fan and a source of electric energy and said pump and a source of electric energy whereby said fan and said pump may be powered by either direct current or alternating current.
14. The cooler of claim 11 wherein said fan and said pump are electrically powered, said cooler further comprising three-way switch means adapted to be coupled between said pump and a source of electric energy and said fan and a source of electric energy whereby either said pump or said fan may be selectively coupled to said source of electric energy, or said pump and said fan may be coupled simultaneously to said source of electric energy.
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