Abstract:
A flow shut off valve for residential water line pressure includes a housing having an inlet, an outlet and a passage there between with a valve seat in the passage. A valve element is slidably mounted within the passage and includes a cavity open to the inlet and orifices partially restricting flow from the cavity to the passage. A spring biases the valve element toward the inlet. Reduced back pressure at the outlet drives the valve element into a closed position with a sealing surface against the valve seat to terminate flow. The restrictive orifices in the valve element extend from the cavity to the periphery of the valve element and, in a position toward the inlet, the restrictive orifices are closed by the housing to block communication between the inlet and the outlet. In an intermediate position, the orifices are open and the sealing surface is not against the valve seat. A motion damper may be employed to allow for start-up conditions on sprinkler systems and the like. The flow shutoff valves are contemplated for employment with household appliances using water and sprinkler systems.

Description:
BACKGROUND OF THE INVENTION 
   The field of the present invention is flow shutoff valves for residential water line pressure. 
   Shutoff valves to prevent excess flow, such as when a sudden leak occurs downstream of the valve, are well known in the art. Such valves are found in high pressure hydraulic systems, fueling systems and critical gas systems. Such valves are relatively expensive because of complicated housings and/or valve elements, the materials, and their precision machining requirements. 
   Household appliances which use water such as a washing machine are most often connected to manual shutoff valves which are installed in the home. The conventional means for connecting the manual shutoff valves to an appliance are typically through flexible hoses. Personal experience and insurance statistics suggest that a great many such manual shutoff valves are not closed when the appliance is not in use. Consequently, the integrity of the flexible hoses remains the only means of containing a household system water pressure to an appliance. Insurance companies in North America report payments amounting to hundreds of millions of dollars annually which solely result from broken household appliance hoses. 
   The shutoff valves used for hydraulics, fuels and gasses are out of practical range for use with home appliances. However, other solutions have been applied to the problem of residential flooding from appliance hoses in a number of ways. Electrical sensors, timers and valve drives have been devised. Mechanical devices have also been employed which are complicated, expensive and/or limited in their use. 
   One problem which must be addressed by shutoff devices for residential use is the presence of particles and hardness in the water supply which can accumulate to disable such valves. The utility of most shutoff valves is as an emergency device with very infrequent actuation. Consequently, interfering deposits can be built up with continued flow through the valve without actuation and result in malfunction of the valve when needed. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a flow shutoff valve for residential water line pressure and includes a housing, a valve element slidably mounted in the housing and a spring biasing the valve element. The housing includes a passage therethrough with at least a first cylindrical section. The valve element includes a sealing surface which is engageable with a valve seat about the passage in the housing. A flow restrictive passage is located between the inlet and the outlet with communication therethrough controlled by the valve element. 
   In a first separate aspect of the present invention, the valve element includes a cylindrical wall slidably engaging the first cylindrical section of the passage through the housing. Communication through the flow restrictive passage is closed with the valve element at the inlet end of its slidable mounting. Under this condition, the valve element operates as a piston through a distance responsive to the water pressure each time water begins to flow through the valve, performing a forced physical cleaning. 
   In a second separate aspect of the present invention, the valve element includes a cavity open to the inlet. The flow restrictive passage includes at least one restrictive orifice extending from the cavity to the periphery of the valve element. The restrictive orifice(s) is closed by the first cylindrical section with the valve element at the inlet end of its slidable mounting. 
   In a third separate aspect of the present invention, back pressure at the outlet dropping to near zero gauge pressure results in a force on the valve element greater than and opposed to the force of the spring. Further, the spring has a spring force with the valve element in the no-flow position which is less than the total force of the water line pressure on the valve element with the back pressure of the outlet at near zero gauge pressure. 
   In a fourth separate aspect of the present invention, the flow shutoff valve includes a motion damper operatively coupled between the housing and the valve element. This damper may include damping which is progressive with displacement. The motion damper may include a cavity and a plunger. The plunger can have an increasing cross-sectional area with increasing distance from the free end of the plunger for a first length of the plunger. 
   In a fifth separate aspect of the present invention, the flow shutoff valve includes a flexible hose having a proximal end attached to the outlet and a distal end, a line filter adjacent the distal end of the flexible hose and no line filter adjacent the proximal end of the hose or the flow shutoff valve. 
   In a sixth separate aspect of the present invention, any of the foregoing aspects are contemplated to be employed in combination to greater utility. 
   Accordingly, it is an object of the present invention to provide an improved flow shutoff valve. Other and further objects and advantages will appear hereinafter. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional view taken along the centerline of a flow shutoff valve in a position with no flow therethrough. 
       FIG. 2  is a cross-sectional view taken along the centerline of the flow shutoff valve in an intermediate position with flow therethrough. 
       FIG. 3  is a cross-sectional view taken along the centerline of a flow shutoff valve in a shutoff position. 
       FIG. 4  is a bottom view of a second embodiment of a flow shutoff valve. 
       FIG. 5  is a cross-sectional view taken along lines  5 - 5  of  FIG. 4 . 
       FIG. 6  is a perspective exploded assembly view of flow shutoff valves with an appliance. 
       FIG. 7  is a perspective view of a flow shutoff valve with a sprinkler system. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Turning in detail to  FIGS. 1 through 3 , a self cleaning flow shutoff valve for residential water line pressure is disclosed. The flow shutoff valve, generally designated  10 , includes a housing  12 . The housing  12  is constructed of an inlet section  14 , and an outlet section  16 . These sections may conveniently be of inexpensive plastic molding material. Such materials include polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), acrylonitrile butadiene styrene (ABS) and other plastics. Brass or bronze may alternatively be employed. The sections  14 ,  16  are generally cylindrical. “Cylindrical” is used herein in the broader mathematical sense without necessarily being limited to a circular cylinder. 
   The inlet section  14  includes an inlet  18 . The outlet section  16  includes an outlet  20 . The inlet  18  and outlet  20  sections are shown to be threaded with female and male threads, respectively. The entire body of the housing  12  is preferably cylindrical at any cross section and the two sections  14 ,  16  include male and female engaged pilot diameters. The two sections  14 ,  16  may be bonded together or threaded together with an o-ring seal  40 . 
   The resulting housing  12  defined by the two sections  14 ,  16  includes a passage  21  therethrough extending from the inlet  18  to the outlet  20 . The passage  21  includes a washer  22  arranged at the inlet to prevent flow from backing out through the inlet  18 . 
   The passage  21  further includes a cylindrical section  24  found inwardly of the inlet  18  and washer  22 . This section  24  extends to a central section  26  of enlarged cross section also forming part of the passage  21 . At one end of the central section  26 , an annular spring seat  28  is arranged to accommodate a spring inwardly displaced from the wall of the passage  21  at the central section  26 . A valve seat  30  is also located in the central section  26  at the annular spring seat  28 . The valve seat  30  extends around the passage  21  as it defines an outlet channel  32 . 
   A valve element  34  includes a cylindrical wall about its periphery which slidably engages the cylindrical section  24 . The body  36  of the valve element  34  is of sufficient length and fit so that it will not bind with the cylindrical bore  24  in movement within the passage  21  and yet precludes any substantial flow between the cylindrical wall and the cylindrical section  24 . The clearance between the body  36  and the cylindrical bore  24  is small but does not require that all fluid flow therebetween be prevented. A retaining ring  38  fits within a groove in the passage  21  at the first section  24 . A spring clip may be employed for this ring  38 . This limits the travel of the valve element  34  toward the inlet  18 . A nose  42  of smaller diameter than the body  36  extends downwardly below the cylindrical wall of the body  36 . 
   A flow restrictive passage is located between the inlet and the outlet with communication therethrough controlled by the valve element  34 . In the preferred embodiment, the flow restrictive passage is defined by a central cavity  44  extending into the body of the valve element  34  from the inlet end. The cavity  44  does not extend fully through the valve element  34 . Rather, several orifices  46  extend from the cavity  44  in a radial direction to the periphery of the valve element  34  for communication between the inlet and the outlet. Further the central section  26  can provide communication from the orifices  46  to the valve seat  30 . A sealing surface  48  is arranged on the end of the nose  42  to cooperate with the valve seat  30  for closure of the passage  21 . 
   A spring  50  is positioned in the annular spring seat  28  and is placed in compression against the shoulder created by the diameter change in the valve element  34 . The spring  50  biases the valve element  34  toward the inlet and against the retaining ring  38 . 
   In comparing  FIGS. 1 ,  2  and  3 , it may be noted that the valve element  34  is shown in three functional positions. A first position, as illustrated in  FIG. 1 , is with the valve element  34  positioned fully toward the inlet  18 . A second position, as illustrated in  FIG. 2 , is an intermediate position with the orifices  46  in communication with the central section  26  and the valve  10  open. The second position actually spans a range of locations for the valve element  34 . A third position, as illustrated in  FIG. 3 , is with the sealing surface  48  pressed against the valve seat  30 . In the first position, the orifices  46  are closed by the cylindrical section  24  which closely surrounds the cylindrical periphery of the valve element  34 . In this way, communication through the flow restrictive passage is closed. With no open passage, pressure builds up on the top of the valve element  34  which in turn acts as a piston and is forced downwardly by the water pressure every time the valve is opened. With the added force of the piston, the valve element  34  is cleared of any accumulation of particles and hardness on a regular basis. Further, the valve remains open with the sealing surface  48  displaced from the valve seat  30 . 
   In the second position, flow proceeds relatively unimpeded by the mechanism with the exception of the design of the orifices  46 . Under normal flow conditions, the valve element  34  remains in this intermediate position. 
   In the third position, the sealing surface  48  is on the valve seat  30  and there is no flow. It is through this range of positions that the flow shutoff valve  10  operates. 
   The spring  50  and the orifices  46  are empirically selected to accommodate residential water line pressure and household appliance flow rates. At normal flow, there is some pressure drop across the valve element  34 . This pressure drop is due to flow resistance through the orifices  46  and general drag on the valve element  34 . This pressure drop along with pressure imbalances resting from velocity variations around the valve element  34  provide differential forces on the valve element  34 . However, the orifices  46  and the spring  50  are selected to allow a certain range of flow through the flow shutoff valve  10  at a range of line pressures with the spring  50  retaining the valve element  34  in the intermediate zone of positions. This is accomplished by having the spring maintain a range of force on the valve element  34  that the hydraulic forces do not move the valve element  34  fully to the third position against the valve seat  30 . Naturally, the spring  50  cannot resist the piston action of the valve element  34  as it moves from the first position to expose the orifices  46 . As the residential water line pressure is reasonably stable during such flow, the back pressure at the outlet  20  significantly determines flow rate. This back pressure is developed at an appliance or other device in fluid communication with the outlet  20 . 
   When the back pressure at the outlet  20  drops significantly, the differential pressure between the inlet  18  and the outlet  20  becomes substantially greater. In response, flow through the flow shutoff valve  10  increases. As the flow increases, greater resistance is provided by the orifices  46 . Resulting hydraulic forces acting in the direction of flow increase. At a flow rate between 150% and 200% of anticipated normal flow, the resulting hydraulic force on the valve element  44  exceeds the opposing spring force from the compressed spring  50 . Preferably the spring  50  is arranged such that the distance between the first and third positions does not greatly increase the spring force. This is accomplished with some precompression of the spring  50  in the first position and a small spring constant. With the resulting hydraulic force exceeding the spring force, the valve element  34  will move to the third position with the sealing surface  48  against the annular valve seat  30 . As the sealing surface  48  engages the valve seat  30 , flow is terminated. 
   Once there is no flow, the pressure about the valve element  34  equalizes at the line pressure. At this point, the only forces on the valve element  34  are the spring  50  and the imbalance between the line pressure and the lower pressure at the outlet channel  32  operating on the valve element  34  inwardly of the valve seat  30 . With the outlet  20  being near zero gauge pressure, the differential pressure across the area of the outlet channel  32  retains the valve element  34  in the third position. Reinstating the flow shutoff  10  to the first or second positions is accomplished by reducing the line pressure sufficiently so that the spring  50  may force the valve element  34  back toward the inlet  18 . 
   The second embodiment illustrated in  FIGS. 4 and 5  includes the reference numbers applied to the first embodiment where functions are substantially identical. This second embodiment of the flow shutoff valve, generally designated  51 , principally differs in the provision of a motion damper, generally designated  52 . The motion damper includes a cavity  54  associated with the housing  12  and a plunger  56  associated with the valve element  34 . The first position of the valve element  34  as seen in  FIG. 5 , has the plunger  56  just entering the cavity  54 . In the intermediate position, the plunger  56  has more fully entered into the cavity  54  but has not bottomed out. 
   For a first distance, the plunger  56  increases in cross-sectional area by means of the chamfer  58 . With this device, the damping resistance is progressive with displacement of the valve element  34  from the intermediate position toward the valve closed position. 
   To accommodate the motion damper  52 , the housing  12  includes an insert  60  centrally defining the cavity  54  with multiple ports  62  thereabout. The ports are substantially larger in cumulative cross-section than the orifices  46 . This allows a rapid drop in pressure below the valve element  34  with resulting closure of the shutoff valve  51  when pressure at the outlet  20  drops to near zero gauge. The insert  60  may be press fit or retained by bonding. A further variation from the first embodiment may be the employment of slip sockets, as the shutoff valve  51  is depicted in  FIG. 7 , particularly adaptable with PVC, CPVC and ABS type piping systems for bonding of the system components to the valve  51 . 
     FIG. 6  illustrates the use of flow shutoff valves  10  with a home appliance such as a washing machine  66 . Flexible hoses  68 ,  70  are coupled with the flow shutoff valves  10  which are in turn coupled with the standard manual valves  64 ,  72 . In the circumstance that a flexible hose  68 ,  70  breaks, water pressure within the hose and correspondingly at the outlet  20  would drop to near zero gauge pressure. Under this circumstance, the flow shutoff valve  10  would close by having the valve element  34  moved to the second position. The corresponding valve  64 ,  72  must then be closed before flow is restored through the flow shutoff valve  10 . 
   The hoses  68  and  70  have proximal ends adjacent the shutoff valve  10  and distal ends at the appliance  66  or other device. A line filter  74  may be located adjacent the distal end of each of the hoses  68  and  70 , where they connect to the appliance solenoid valves,  75  and  76 , and no line filter is located adjacent the proximal end of the hoses  68  and  70  or the flow shutoff valve  10 . As indicated above, particles and hardness accumulate from a domestic water line. If there is a filter before the flow shutoff valve  10 , there is the danger of sufficiently clogging the line filter enough that flow would never reach the shutoff velocity through the flow shutoff valve  10  to properly actuate with a break in the hose. By placing line filters after the hoses, the increased flow from a break would not be reduced by an upstream clogged line filter. 
     FIG. 7  illustrates a sprinkler system including sprinklers  74 , an anti-siphon valve  76  and sprinkler pipes  78 . The motion damper  52  of the second embodiment has particular utility in the sprinkler system of  FIG. 7 . When the anti-siphon valve  76  is closed, the anti-siphon operates to release pressure and drain some of the sprinkler pipe  78 . Therefore, when the anti-siphon valve is again opened, there is the possibility that the sprinkler piping  78 , and correspondingly the outlet  20 , will be at near zero gauge pressure until filled by line water. Without slowing the closure of the valve, this condition could prematurely close the shutoff valve. 
   Thus, relatively simple, inexpensive and reliably responsive and self cleaning flow shutoff valving has been disclosed. While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. The invention, therefore is not to be restricted except in the spirit of the appended claims.