Abstract:
A hydrant comprising a housing forming a reservoir; and a piston configured to force residual fluid out of the reservoir to an outlet and to allow supply fluid to flow from an inlet through the piston to the outlet when the piston is actuated in the housing to a first position, and when the piston is actuated in the housing to a second position, to restrict flow of the supply fluid to the outlet and to allow at least a portion of the supply fluid that has flowed from the inlet to flow into the reservoir thereby becoming new residual fluid.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention is related to the field of fluid hydrants. 
   2. Statement of the Problem 
   Fluid hydrants are commonly used in conditions which demand sanitary performance when the operating temperature drops below freezing. Sanitary operation includes backflow protection, drain to ground and ground to drain restrictions and quick and easy evacuation of residual water. Past hydrant designs have focused on locating a reservoir below the freeze line into which residual flow of the supply fluid drains upon cessation of flow. The residual water is then purged from the reservoir using expensive and time consuming venturi check-valves during normal operation (See U.S. Pat. No. 5,701,925) or complicated residual fluid diverter lines that add cost and complexity (See U.S. Pat. No. 6,427,716). 
   SUMMARY OF THE SOLUTION 
   The present invention helps solve the problems associated with unsanitary and below-freezing operation using an actuated piston system that allows for the removal of residual fluid through the same outlet as the supply fluid. 
   Some examples of the hydrant include a housing forming a reservoir and a piston traveling in the housing. The piston is configured to force residual fluid out of the reservoir to an outlet and to allow supply fluid to flow from an inlet through the piston to the outlet when the piston is actuated in a first position. When the piston is actuated in a second position, the piston operates to restrict flow of the supply fluid to the outlet and to allow at least a portion of the supply fluid that has flowed from the inlet to flow into the reservoir thereby becoming new residual fluid. 
   In some examples, a first portion of the housing containing the reservoir is configured to be located in the ground below a frost line and a second portion of the housing is configured to be located above the frost line. The above described location of the hydrant allows for the residual fluid to exit the housing above the ground when the piston is actuated to the first position thereby inhibiting contamination of the supply fluid. The location also inhibits freezing of the residual fluid by allowing the residual fluid to enter the reservoir when the piston is actuated to the second position 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates the basic structure of a typical yard hydrant. 
       FIGS. 2A–C  illustrate a hydrant in an example of the invention. 
       FIGS. 3A–C  illustrate a hydrant in an example of the invention. 
       FIGS. 4A–C  illustrate a hydrant in an example of the invention. 
       FIGS. 5A–D  illustrate a hydrant in an example of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1–5  and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents. 
     FIG. 1  illustrates the basic structure of a typical yard hydrant  100 . Hydrant  100  includes a head assembly  102  and a body assembly  104 . Head assembly  102  is positioned atop body assembly  104  and comprises actuator  106  coupled to operating shaft  108  by any suitable linkage mechanism. Operating shaft  108  enters the body assembly  104  through an entrance at the top of supply housing  110 . Body assembly  104  includes supply housing  110  which is coupled to piston housing  112  and supply inlet  114 . 
   In operation, a user actuates actuator  106  causing operating shaft  108  to lower into supply housing  110  and piston housing  112 . The lowering of operating shaft  108  initiates flow from supply inlet  114  through portions of hydrant  100  and out through discharge  116 . 
   EXAMPLE 1 
     FIGS. 2   a–c  illustrates a detailed body assembly  204  in a first example of the invention. Body assembly  204  includes an inlet  114 , piston housing  112 , reservoir  222 , and piston  225 . Piston housing  112  forms reservoir  222 . Piston  225  travels in piston housing  112  and includes flow passage  227 . 
   In operation, piston  225  is in its purge position as shown in  FIG. 2A . When operating, shaft  108  lowers piston  225  into reservoir  222  forcing the residual water in reservoir  222  through outlet  216 . Once piston  225  is located in reservoir  222 , as shown in  FIG. 2B , inlet  114  is aligned with flow passage  227  allowing supply fluid to travel through piston  225  and outlet  216 . Outlet  216  is shown near the reservoir but can be located as desired. 
   In  FIG. 2C , piston  225  is in its drain position. Operating shaft  108  moves piston  225  out of alignment with inlet  114  and out of reservoir  222 . Any fluid left in hydrant  100  flows back into reservoir  222  becoming residual fluid. 
   Advantageously, in some variations the fluid hydrant can be used to restrict freezing, while operating in a sanitary manner. This is achieved by allowing residual fluid left in the hydrant to flow into the reservoir located below the freeze line when flow is stopped followed by evacuation of the reservoir when flow is resumed. The reservoir provides for sanitary operation by eliminating underground cross-connection. Sanitary operation is provided by the reservoir which eliminates underground cross-connection. 
   EXAMPLE 2 
     FIGS. 3   a–c  illustrates a detailed body assembly  304  in a second example of the invention. Body assembly  304  includes an inlet  114 , piston housing  112 , reservoir  322 , and piston  325 . Piston housing  112  forms reservoir  322 . 
   Piston  325  travels in piston housing  112  and includes flow passage  327 , upper and lower flow passage sealing rings  329  &amp;  331  and upper and lower inlet sealing rings  332  &amp;  334 . Upper and lower flow passage sealing rings  329  &amp;  331  seal off flow passage  327  from reservoir  322  and the upper housing area. Upper and lower inlet sealing rings  332  &amp;  334  seal off inlet  114  from the interior of piston housing  112 . Seals  329 ,  331 ,  332  and  334  seal off the various portions of the housing by compressing against and riding along the inner surface of piston housing  112  as piston  325  is actuated. 
   Piston housing  112  comprises inlet  114 , outlets  324  and  326  and forms reservoir  322 . Outlets  324  and  326  combine to form flow passage  328 . Flow passage  328  is coupled to discharge outlet  116 . 
   In operation, piston  325  is in its purge position as shown in  FIG. 3A . An operator, either manually or remotely, actuates actuator  106  causing operating shaft  108  to lower piston  325  into reservoir  322 , forcing the residual water in reservoir  322  through outlet  326 , flow passage  328  and discharge outlet  116 . Once piston  325  is located in reservoir  322 , as shown in  FIG. 3B , inlet  114  is aligned with flow passage  327  allowing supply fluid to travel through piston  325 , outlet  324 , flow passage  328  and discharge outlet  116 . 
   In  FIG. 3C , piston  325  is in its drain position. The operator actuates actuator  116  causing operating shaft  108  to raise piston  325  out of alignment with inlet  114  and out of reservoir  322 . Any fluid left in flow passage  328  flows flow back into reservoir  322  becoming residual fluid. 
   EXAMPLE 3 
     FIGS. 4   a–c  illustrates a detailed body assembly  404  in a third example of the invention. Body assembly  404  includes an inlet  114 , piston housing  112 , reservoir  422 , and piston  425 . 
   Piston  425  includes flow passage  427 , vent channel  432 , outlet  423 , vent valve  434 , check valve  436 , drain passage  424 , flow channel  430  and upper and lower sealing rings  429  &amp;  431 . Sealing rings  429  &amp;  431  seal off the various portions of the housing by compressing against and riding along the inner surface of housing  112  as piston  425  is actuated. 
   Housing  112  comprises inlet  114 , drain channel  426  and forms reservoir  422 . Operating shaft  108 , having a hollow interior forming flow conduit  428 , is coupled to outlet  423  and exits head assembly  102  through an exit opening in the top of supply housing  110 . Operating shaft  108  is coupled to discharge outlet  116 . 
   In operation, piston  425  is in its purge position as shown in  FIG. 4A . An operator, either manually or remotely, actuates actuator  106  causing operating shaft  108  to lower piston  425  into reservoir  422 , forcing the residual water in reservoir  422  through check valve  436 , flow channel  430 , outlet  423 , flow conduit  428  and discharge outlet  116 . Once piston  425  is located in reservoir  422 , as shown in  FIG. 4B , inlet  114  is aligned with flow passage  427  allowing supply fluid to travel through piston  425  via flow channel  430  and outlet  423 , flow conduit  428  and discharge outlet  116 . 
   In  FIG. 4C , piston  425  is in its drain position. The operator actuates actuator  106  causing operating shaft  108  to raise piston  425  off of alignment with inlet  114  and out of reservoir  422 . Vent valve  434  allows air to enter the reservoir  422  through vent channel  432  in order to break the vacuum caused by the movement of piston  425 . Any fluid left in flow channel  430  and flow conduit  428  flows flow back into reservoir  422  through drain passage  424  and drain channel  426  becoming residual fluid. 
   EXAMPLE 4 
     FIGS. 5   a–c  illustrates a detailed body assembly  504  in a fourth example of the invention. Body assembly  504  includes an inlet  114 , piston housing  112 , fluid reservoir  522 , air reservoir  538  and piston  525 . 
   Piston  525  includes flow passage  527 , vent channel  532 , outlet  523 , drain passage  524 , flow channel  530  and sealing rings  529 ,  531 ,  533 ,  540 ,  541  &amp;  542 . Sealing rings  529 ,  531 ,  533  &amp;  535  seal off the various portions of housing  112  by compressing against and riding along the inner surface of housing  112  as piston  525  is actuated. Sealing rings  540 ,  541  &amp;  542  seal off the various portions of air reservoir  538  by compressing against and riding along the outer surface of piston  525  as piston  525  is actuated. 
   Housing  112  comprises inlet  114  and forms fluid reservoir  522 . Operating shaft  108 , having a hollow interior forming flow conduit  528 , is coupled to outlet  523  and exits head assembly  102  through an exit opening in the top of supply housing  110 . Operating shaft  108  is coupled to discharge outlet  116 . 
   In operation, piston  525  is in its purge position as shown in  FIG. 5A . An operator, either manually or remotely, actuates actuator  106  causing operating shaft  108  to lower piston  525  and air reservoir  538  into fluid reservoir  522 , forcing the residual water in reservoir  522  through drain channel  526 , drain passage  524 , flow channel  530 , outlet  523 , flow conduit  528  and discharge outlet  116 . The spaced apart relationship between piston  525  and air reservoir  538  is maintained by spring  550  located in the air reservoir. Supply inlet  114  is blocked during this operation. Once air reservoir  538  is fully seated in fluid reservoir  522 , piston  525  begins to compress spring  550  allowing piston  525  to lower into air reservoir  538 , as shown in  FIG. 5B . Air that is contained in air reservoir  538  is forced out of air reservoir  538  through vent channel  532  and into supply housing  110 . The air in supply housing  110  can be vented to atmosphere using any standard venting mechanism. 
   As shown in  FIG. 5C , supply fluid from inlet  114  begins to flow when piston  525  is seated in air reservoir  538  and air reservoir  538  is seated in fluid reservoir  522 . Inlet  114  is aligned with flow passage  527  allowing supply fluid to travel through piston  525  via flow channel  530  and outlet  523 , flow conduit  528  and discharge outlet  116 . 
   In  FIG. 5D , piston  525  is in its drain position. The operator actuates actuator  106  causing operating shaft  108  to raise piston  525  off of alignment with inlet  114  and out of air reservoir  538 . Air enters air reservoir  538  through vent channel  532  in order to break the vacuum caused by the movement of piston  525 . When drain passage  524  of piston  525  aligns with drain channel  526  of air reservoir  538 , piston  525  moves air reservoir  538  out of fluid reservoir  522 . Fluid left in flow channel  530  and flow conduit  528  flows flow back into fluid reservoir  522  through drain passage  524  and drain channel  526  becoming residual fluid.