Patent Publication Number: US-6220957-B1

Title: Reversing shuttle for air handling device

Description:
FIELD OF THE INVENTION 
     The invention pertains to the field of air handling devices. More particularly, the invention pertains to a reversing shuttle for an air handling device that reverses air flow in part of the device. 
     BACKGROUND OF THE INVENTION 
     In a system for treating soil and turf by blowing and/or vacuuming through a duct network located underneath the turf, a low-pressure high-volume fan is typically used to move air into the soil profile or suck moisture out of the soil profile. U.S. Pat. Nos. 5,433,759; 5,507,595; 5,542,208; 5,617,670; 5,596,836; and 5,636,473 show different variations on equipment used for this purpose. Since a non-reversing fan always rotates in the same direction, changing the system from a blowing function to a vacuuming function requires disconnecting the duct network from the blowing outlet of the fan unit and connecting it to the vacuum inlet of the unit. In some variations, a 4-way valve is used to avoid the hassles involved with selectively connecting and disconnecting the duct network from the various ports of the fan unit. 
     SUMMARY OF THE INVENTION 
     Briefly stated, a fan unit has inlet and outlet ducts facing in the same direction. A reversing shuttle is connected to the inlet and outlet ducts of the fan unit and includes a diverter damper and two opposing dampers. The reversing shuttle further includes an outlet that is connectable to a duct network that is under a sports field or portions of a golf course. When the fan unit is running, depending on how the opposing dampers and diverter damper are positioned, air is either blown into the duct network, thereby causing air and possibly other additives to enter the soil profile of the field, or sucked (vacuumed) from the duct network, thereby draining moisture through the soil profile and into the duct network. Moving the diverter damper from a first position to a second position while changing which of the opposing dampers is open and which is closed reverses the air flow in the duct network. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a top plan schematic view of a reversing shuttle according to an embodiment of the invention as used in an air handling device. 
     FIG. 2 shows a top plan schematic view of the reversing shuttle of FIG. 1 used to explain the operation of the invention. 
     FIG. 3 shows a schematic view of the air handling device as part of a larger air handling system according to an embodiment of the invention. 
     FIG. 4 shows a schematic view of an embodiment of the air handling system of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, an air handling device  10  includes a reversing shuttle  20  that is connected to a fan box  30 . Reversing shuttle  20  includes a vacuum side damper  22  on one side and a pressure side damper  23  on another side. A connection portion  24  connects to a supply line (not shown) that connects air handling device  10  to a duct network  15  (FIG. 3) of a sports field (not shown). Dampers  22 ,  23  are preferably linked together so that when one damper is closed, the opposite damper is open, and vice versa. Dampers  22 ,  23  can be opposed operation actuated dampers to ensure that dampers  22 ,  23  are in opposed operation. A diverter damper  25  extends from a pivot point  26  to a seat  27   a  when air handling device  10  is in a vacuum mode and to a seat  27   b  when air handling device  10  is in a blowing mode. Diverter damper  25  and seats  27   a ,  27   b  are preferably curved so as to avoid inefficiencies in the system by minimizing turbulence and maintaining laminar flow. 
     Diverter damper  25  is preferably of carbon steel, but other materials that are suitably strong and durable can be used. Diverter damper  25  is preferably manually, electrically, or pneumatically actuated. When electrically or pneumatically actuated, a separate manual control is optional. Diverter damper  25  could be hydraulically actuated, but for most applications, this is not required. 
     Fan box  30  includes a fan inlet  31  which is connected on one end to an inlet box  32  and on the other end to reversing shuttle  20 . Inlet box  32  is in turn connected to a fan housing  33  which preferably contains a conventional impeller type fan (not shown), although selecting the particular type of fan for a given installation is within the ability of one skilled in the art. Fan housing  33  is connected to a fan outlet  34  which in turn is connected to reversing shuttle  20 . The geometries of fan inlet  31  and fan outlet  34  are such as to prevent inefficiencies in the system due to turbulence. 
     When diverter damper  25  is positioned as shown in FIG. 1, air enters reversing shuttle  20  via connector  24  as shown by arrow (a) because damper  22  is closed and damper  23  is open. The air moves through fan box  30  as shown by arrow (b) and exits to atmosphere through reversing shuttle  20  as shown by arrow (c). 
     Referring to FIG. 2, diverter damper  25  is seated against seat  27   b  and damper  22  is open while damper  23  is closed. The air therefore enters reversing shuttle  20  as shown by arrow (d), moves through fan box  30  as shown by arrow (b), and exits reversing shuttle  20  through connector  24  as shown by arrow (e). 
     Referring to FIG. 3, an embodiment of the invention has dampers  22 ,  23  and diverter damper  25  automatically controlled by a control unit  40  that preferably includes a microcontroller (not shown) operating to a control logic preferably input by a user via a device such as a PC  48 . The PC  48  is optionally connected to a communications interface  49  such as a dial-in modem or internet connection to permit remote programming of the control logic. A plurality of sensors  42 ,  44 ,  46  that measure variables such as temperature, moisture, composition of soil gasses, etc, are linked to reversing shuttle  20  via control unit  40  to automatically control the direction of air flow through duct network  15 . This is critical when operating air handling device  10  in an automatic mode, because if the turf being treated contains too much moisture, blowing air from air handling device  10  through duct network  15  can accidentally blow the turf out of the field in spots. Contrariwise, operating air handling device  10  in a vacuum mode when the turf is already dry will suck needed moisture out of the turf. Appropriate sensors such as those manufactured by Aqua-Flex, of New Zealand, placed in or just under the turf, preferably within the root zone or just below, permit proper automatic control of air handling device  10 . 
     Referring to FIG. 4, an embodiment of the invention includes a heat exchanger  50  to maintain the turf at a desired temperature. For example, soccer pitches in Europe must be natural turf instead of artificial turf, and the turf/ground cannot be so frozen such that the players&#39; cleats are unable to make an impression in the turf/ground. Temperature sensors strategically located around the pitch are tied in to control unit  40  which is connected to heat exchanger  50 . The control logic for control unit  40  is preferably programmable by the user to maintain optimal field conditions using temperature and moisture as the variables to control the direction of air movement, time that air is being moved, and the temperature of the air being moved into the duct network as the operating parameters of the air handling system. In an alternate embodiment, control unit  40  can be optionally set to control the operating parameters based on time of day and season. 
     Another consideration when operating the invention in climates where freezing is likely to occur is that the specific heat of sand, which is frequently used in sports field construction, is 0.2 BTU/lb-deg F., which is only one-fifth that of water. Removing excess moisture from a sports field before the field freezes significantly reduces the amount of heat required to unfreeze the field and place it in condition suitable for sports play. In a variation of this embodiment, a supply line between air handling device  10  and duct network  15  is buried underground a sufficient depth to take advantage of ground effect heat exchange. The term “heat exchanger” as used in this application includes such a buried supply line. 
     An alternate embodiment of the air handling system of the present invention uses manual decision-making instead of programmed logic. The output from sensors  42 ,  44 ,  46  is shown on the screen of PC  48  and interpreted by the user. The user then can use the PC to control air handling device  10  and optionally heat exchanger  50 , or in a simpler system, control air handling device  10  and heat exchanger  50  manually. 
     Accordingly, it is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments are not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention.