Abstract:
A flow control valve is disclosed wherein a housing defines a flow chamber with an inlet and an outlet. Disposed within the flow chamber is a telescoping poppet comprising an inner poppet and an outer poppet. A first spring is selected to bias the outer poppet to seal closed the inlet below a predetermined fluid flow rate. Above the fluid flow rate, the force of the fluid against the outer poppet compresses the spring, breaking the seal and allowing fluid to flow into the fluid flow chamber. Inside the outer poppet is an inner poppet which telescopes from the outer poppet. A second spring biases the inner poppet predominantly within the outer poppet, but an increased pressure in the outer poppet collapses the second spring and extends the inner poppet in a fully extended position. Fully extended the inner poppet seals shut the outlet of the fluid chamber. In operation, the first spring shuts the valve below a predetermined flow rate guaranteeing zero flow until a minimum flow rate is present. Furthermore, if a leak occurs downstream (beyond the outlet) or the flow rate is above a predetermined maximum flow rate the second spring is collapsed by an upstream/downstream pressure differential causing the inner poppet to seal the outlet. Thus, the valve operates only between a minimum and maximum flow rate and seals in the event of a downstream leak.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to flow control valves, and more particularly to a purely mechanical leak arresting flow control valves that regulate fluid flow between a minimum flow rate and a maximum flow rate, and can detect leaks below and above the minimum and maximum flow rates, respectively, and close the valve in the presence of a leak. 
     2. Description of Related Art 
     Valves used in the regulation of fluid flow are well known in the art. Valves can be used to maintain fluid flow in a particular direction, or as a safety feature to prevent too high of a flow rate or too low of a flow rate. Valves can be mechanically or electrically actuated devices that use the dynamic pressure in a fluid flow to compress a spring or move a ball, thereby allowing the fluid either to pass through the valve or be blocked by the valve. 
     The present invention is directed to a flow regulating valve which allows continuous fluid flow in a predetermined range, as opposed to a pulse flow. Valves used for this purpose are useful for many applications which require a supply of a liquid or a gas, collectively a fluid, such as a washing machine, ice maker, or gas stove. The present invention includes a new feature not found in the prior art valves, namely, a purely mechanical leak detecting function. The invention is a mechanical valve which regulates the flow of fluid within a predetermined minimum and maximum flow rate, and further mechanically closes the valve when either a small or large downstream leak occurs. Thus, while prior art purely mechanical safety valves will close shut, and thereby stop the fluid flow if a major leak occurs due to the sudden increase in the fluid flow rate, the prior art valves lack the ability to close shut in the event of a small leak such as might occur due to a small breach in the downstream fluid line or the gradual failure of a downstream component. This situation could be of critical importance if, say, the fluid is hazardous or flammable, if the fluid line is not regularly maintained due to its location or conditions of use, or if subsequent damage from such a line breach would be economically or environmentally unacceptable. The response of the valve may be the only indication that a small leak has occurred. The present invention solves the problem that the prior art valves fail to address. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a valve housing forming a flow chamber thereinthrough with an inlet and an outlet. Within the flow chamber is a flow arresting member comprising a pair of poppets cooperating to telescope within the flow chamber. The first poppet is a hollow outer poppet biased against the valve inlet by a first spring, shutting the valve to flow rates below a predetermined minimum flow rate governed by the spring constant. Within the first outer poppet is a second inner poppet anchored within the first poppet and extending through an opening in the outer poppet in a telescoping relationship. The second poppet is biased in the first poppet by a second spring such that the second poppet extends from the first poppet when the fluid pressure in the cavity of the first poppet exceeds the pressure at the outlet of the valve by more than a critical value determined by the second spring constant. When the second poppet fully extends (or “telescopes”) from the first poppet, the second poppet plugs the outlet and closes the valve to subsequent fluid flow through the valve. This condition occurs when either a small leak or a large leak occurs is present downstream of the valve. Further, if a flow rate is too large, the first outer poppet will completely collapse its biasing spring such that the outlet to the valve is blocked. Thus, only a predetermined flow rate between a minimum flow rate and a maximum flow rate is permitted through the valve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The exact nature of this invention, as well as its objects and advantages, will become readily apparent upon reference to the following detailed description when considered in conjunction with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof, and wherein: 
     FIG. 1 is a cross sectional view of a preferred embodiment of the resent invention illustrating a condition below a minimum flow rate; 
     FIG. 2 is a cross sectional view of a preferred embodiment of the present invention illustrating a condition between a minimum flow rate and a maximum flow rate; 
     FIG. 3 is a cross sectional view of a preferred embodiment of the present invention in the presence of a leak; and 
     FIG. 4 is a cross sectional view of a preferred embodiment of the present invention illustrating a condition above a maximum flow rate. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventor of carrying out his invention. Various modifications, however, will remain readily apparent to those skilled in the art, since the general principles of the present invention have been defined herein specifically to provide a mechanical leak arresting valve. 
     FIG. 1 illustrates a valve (generally denoted  100 ) having a housing with an inlet side  103  and an outlet side  104 . The housing is formed by two mating halves, a male half  102  with a threaded portion  106  and a female half  101  with a threaded portion  105 . The two halves  101 , 102  engage via the mating threaded portions  105 , 106  to form a fluid-tight valve. The valve  100  has a threaded inlet  107  designed to receive a piping component (not shown) ultimately connected to a fluid source, and threaded outlet  108  adapted to fit in a piping component (not shown) ultimately leading to a fluid recipient. The valve  100  serves as an intermediary between the fluid source and the fluid destination, and shuts off the supply of fluid unless predetermined flow conditions occur in the absence of a downstream leak. For purposes of this disclosure, it is understood that the term “fluid” can refer to either a liquid or a gas and the valve can be designed to operate using both mediums. 
     FIG. 1 shows the inlet  109  as a cylindrical passage funneling out at the entrance to the flow chamber  110  via a chamfered section  111 . The chamfered section  111  terminates at the flow chamber  110 , a cylindrical region within the valve housing. The outlet  112  is also depicted as a cylindrical passage opening to the flow chamber  110  via a chamfered section  113 . The outlet side of the flow chamber includes a recessed region  114  just outside of the outlet chamfer  113 . The recessed region  114  seats a helical spring  115  with a longitudinal axis colinear with a longitudinal axis  116  of both the valve inlet  109  and the valve outlet  112 . 
     The helical spring  115  operates on a telescoping poppet disposed within the flow chamber  110  of the valve  100 . The telescoping poppet includes an outer poppet  117  which has a hollow cylindrical body  118  that is disposed within the helical spring  115 . The hollow body  118  defines a flow cavity  119  therein, and an end  120  of the hollow body  118  of the outer poppet  117  terminates in an opening  121  to the flow cavity  119 . The opening  121  of the outer poppet  117  has a diameter  122  smaller than the internal diameter  123  of the flow cavity  110 , defining an inner shoulder  124  at the opening  121  within the flow cavity  110 . The outer poppet  117  also includes a base  125  with a cylindrical tab of a greater diameter than the outer diameter of the cylindrical body  118 , defining a lip  126  adjacent the end  127  of the outer poppet  117 . The end  128  of the helical spring  115  abuts the lip  126  of the outer poppet  117 , and applies a force thereto in the direction of the inlet side  103  of the valve  100 . Across the lip  126  of the outer poppet  117  is an o-ring  129  seated on a circumferential rim  130 , where the o-ring  129  cooperates with the chamfered portion  111  of the inlet  109  to seal the valve at the inlet when the helical spring  115  forces the outer poppet  117  against the inlet  109  of the valve. 
     The outer poppet  117  is capped at the end  127  by an orifice plate  131  seated in a circumferential recess  132  in the end of the outer poppet  117 . The orifice plate  131  includes a small orifice  133  for communicating fluid from the inlet side of the valve (when the outer poppet is held against the inlet as described above) or from the flow chamber (when the outer poppet is not held against the inlet—see FIG. 2) to the flow cavity  119  inside the outer poppet  117 . Thus, the flow cavity  119  inside the outer poppet  117  is in fluid communication with the upstream fluid conditions via the orifice  133 . 
     Within the outer poppet  117  and anchored inside the flow cavity  119  is a second, inner poppet  134 . The cylindrical body  135  of the inner poppet  134  is preferably longer than the cylindrical body  118  of the outer poppet  117  such that the inner poppet  134  protrudes out of the outer poppet  117  at the opening  121  of the outer poppet  117 . Further, the inner poppet  134  includes a head  140  having a diameter greater than the diameter  122  of the opening  121  of the outer poppet  117  and thus captures the inner poppet  134  inside the outer poppet  117  in a telescoping relationship. A second helical spring  136  is wrapped about the cylindrical body  135  of the inner poppet  134  with a first end  137  abutting the inner shoulder  124  of the outer poppet  117  and the second end  138  abutting the head  140  of the inner poppet  134 . The force of the second helical spring  136  biases the inner poppet  134  against the orifice late  131  in the absence of a pressure differential to collapses the spring. The cylindrical body  135  of the inner poppet  134  is provided with an o-ring  139  sized to seal the outlet  112  of the valve  100  when the inner poppet  134  is forced against the chamfered portion  113  of the outlet  112  of the valve. 
     As will be described more fully below, the combination of the outer poppet  117  and the inner poppet  134  form a telescoping poppet, or flow arresting element, wherein the inner poppet  134  extends through the outer poppet  117  of varying lengths, while remaining permanently anchored within the outer poppet  117 . Depending on varying pressure conditions upstream and downstream of the valve, the two poppets will telescope from a fully retracted position when the inner spring  136  is completely extended to a fully protracted position with the second spring  136  fully compressed. The operation of the valve  100  will now be described in detail. 
     In FIG. 1, the valve is shown in a static condition wherein fluid is present in the valve, but no fluid is flowing through the valve. This condition could occur if an apparatus downstream of the valve drawing fluid from a source upstream of the valve, such as for example a washing machine, completed its cycle and turned off. In this situation, fluid remains in the line, including the valve, and the pressure in the line both upstream of the valve and downstream of the valve is approximately constant. Since the pressure in the upstream side of the valve is approximately equal to the pressure downstream, there is no fluid flow in the line and no pressure differential to move the outer poppet  117 . The helical spring  115  forces the outer poppet  117  against the inlet side of the valve with enough force that the o-ring  129  on the outer poppet  117  is compressed between the outer poppet and the chamfered portion  111  of the valve inlet  109 . The compression of the o-ring  111  seals the valve in a manner such that no fluid can pass into the flow chamber  110  around the outer poppet  117 . 
     Additionally, the pressure at the inlet  109 , and thus at the orifice plate  131 , is approximately equal to the pressure at the outlet  112  and in the flow chamber  110 . Absent a pressure differential, the second helical spring  136  operates on the head  140  of the inner poppet  134  to force the inner poppet against the orifice plate  131  and prevent fluid from entering the flow cavity  119  through the orifice  133 . Therefore, the static flow condition shown in FIG. 1 prevents fluid flow through the valve by completely sealing the inlet  109  of the valve. The valve will remain in this condition until a pressure differential corresponding to a flow rated sufficient to compress the helical spring  115  is experienced by the valve. 
     In FIG. 2, a flow rate is introduced through the valve by a pressure differential between the downstream condition and the upstream condition. This could occur because the fluid recipient, such as a washing machine, is turned on and the fluid (in this case, water) is allowed to enter the washing machine. The flow of water into the washing machine reduces the pressure downstream, creating a pressure differential between the downstream condition and the upstream condition. Without the valve, the presence of a pressure differential would be enough to generate a fluid flow from the higher pressure upstream to the lower pressure downstream. However, the valve denies a fluid flow below a minimum flow rate governed by the selection of the helical spring  115 . The spring is selected so that, below a minimum pressure differential, the force of the spring overcomes the force of the fluid on the orifice plate  131  and the valve remains positioned as shown in FIG.  1 . However, if the pressure differential reaches the minimum pressure differential determined by the spring constant of spring  115 , the pressure on the orifice plate  131  will be greater than the force of the spring  115 , and the two poppets  117 , 134  will traverse in the valve chamber  110  away from the inlet  109 , breaking the seal at the fluid inlet  109 . 
     As FIG. 2 illustrates, if the flow rate remains above the minimum flow rate and below a maximum flow rate, the poppets  117 , 134  will be located between the inlet side of the valve and the outlet side of the valve, permitting fluid to readily flow around the poppet and through the valve. This is the desirable condition when the system is in operational mode and the spring  115  has been selected for the proper flow conditions for the particular fluid recipient. Each fluid recipient, whether it be a dishwasher, a washing machine, or a natural gas stove, would govern the type of spring used to control the movement of the poppets. 
     The function of the orifice plate  131  is to regulate the rate at which the inner poppet  117  telescopes. The inner poppet  134  responds to a reduction in the downstream pressure by translating against the force of the inner spring  136  when the pressure differential inside the cavity  119  is greater than the pressure inside the valve chamber  110  by an amount sufficient to collapse the inner spring  136 . During nominal flow operation, the downstream pressure is reduced and this reduction in downstream pressure is communicated to the valve chamber  110 . However, the pressure in the cavity  119  is slower to equalized (compared to the chamber) because of the size of the orifice  133 , which allows fluid to enter the cavity  119 . The inner poppet  117  responds to the reduction in the downstream pressure by translating or telescoping from the fully retracted position to an extended position. The differential pressure across the orifice  133  eventually causes fluid to fill the cavity  119  between the inner poppet  134  and the outer poppet  117 , until the pressures in the cavity  119  and the chamber  110  are equal. When the cavity  119  equalizes with the valve chamber  110 , the inner poppet  134  is no longer subject to a pressure differential and the inner spring  136  returns the inner poppet  134  to its retracted position (as shown in FIG.  2 ). In this manner, the orifice plate and in particular the orifice itself regulates the rate that the inner poppet telescopes. 
     The spring  115  selected to control the movement of the outer poppet  117  may be either a single stage spring (constant spring coefficient) or a multistage spring with a variable spring coefficient. A multistage spring could allow different flow regimes where the allowable flow rate is governed by a first stage and the onset of fluid flow governs a second flow regime. Thus, if a flow rate of 12 to 15 gallons per minute is needed for a particular application, it is desirable to have a first stage of spring movement wherein the force from the first 12 gpm results in a negligible movement of the spring, but the force applied from 15 gpm is sufficient to compress the spring fully. Thus, the spring will allow the poppet to reside intermediate to both the inlet and the outlet between pressures corresponding to flow rates between 12 and 15 gpm, and the fluid recipient will operate within the specified flow rate. 
     FIG. 3 shows the valve condition in the presence of a small leak downstream of the valve. In many applications it is desirable to halt the flow of fluid when a leak occurs downstream. For example, if the washing machine in the previous example suddenly began to leak water in the non-operating condition, without a valve such as the present invention water could leak indefinitely until discovered, causing damage and even danger. Similarly, in the handling of toxic fluids the importance of the control of leaks are clear. Returning to FIG. 3, the configuration of the valve is initially as that shown in FIG. 1, i.e. a static condition. However, in a small leak condition fluid begins to leak slowly at some point downstream of the valve. Because the inlet side of the valve is sealed below a minimum flow rate, the inlet pressure is isolated from the outlet (or downstream) pressure (see FIG.  1 ). 
     As the leak continues, the pressure downstream drops until a pressure differential between the pressure at the inlet  109  and a pressure at the outlet  112  causes the inner poppet  134  to move away from the orifice plate  131 , permitting fluid to enter the flow cavity  119 . The pressure in the flow cavity  119  approximates the pressure upstream of the inlet, and the difference in pressure between the flow cavity  119  and the flow chamber  110 , i.e. the outlet pressure, causes the inner poppet  134  to extend out of the flow cavity  119 . When the pressure differential reaches a predetermined value, the inner poppet  134  will “telescope” or extend fully from outer poppet  117  such that the o-ring  139  engages the chamfered portion  113  of the outlet  112 . The contact of the o-ring  139  with the outlet closes the flow of fluid through the valve. As long as the leak is present, the downstream pressure will be less than the upstream pressure and the inner poppet  134  will continue to close the valve at the outlet. Thus, the flow of fluid through the valve has been arrested in the presence of a small downstream leak. 
     FIGS. 3 and 4 illustrate the two stages that the valve undergoes in the presence of a large leak, i.e. a sudden loss of pressure downstream of the valve. In this scenario, the equilibrium of FIG. 1 is disturbed when pressure is suddenly lost at the outlet side of the valve, causing the outer poppet  117  to compress the spring completely (FIG.  4 ). The inner poppet  134 , protruding from the outer poppet  117 , reaches the outlet  112  and in cooperation with the o-ring  139  seals the outlet of the valve. This condition is shown in FIG.  4 . With the flow of fluid now arrested by the sealing of the outlet, the pressure in the flow chamber  110  quickly equalizes to the inlet pressure causing the spring  115  to return the outer poppet  117  to its static position abutting the inlet. However, the pressure differential between the inlet  109  and the outlet  112  still exists, and the inner poppet  134  remains extended or telescoped by the pressure differential. Thus, after the equalization of the flow chamber the valve is configured the same as condition as FIG. 3, i.e., the outer poppet  117  is maintained against the inlet  109  sealing the inlet except for the orifice  133  which feeds the flow cavity  119 , and the inner poppet  134  is forced against the outlet  112  and seals the outlet from flow through the valve. Thus with either a small leak or a large leak the valve eventually ends up closing the valve as shown in FIG.  3 . 
     The valve may be optionally equipped with a throttling region  141  just outside the chamfered section  111  of the inlet, shown in FIG. 1 as a narrowing or necking of the flow chamber. The length and tolerances of the throttling region is determined by the particular application. The function of the throttling region controls the amount of fluid escaping past the poppets during the transition stage between static and normal flow conditions. As the outer poppet transitions away from the inlet, the pressure drop decreases as the amount of fluid increases, which in turn affects the way the valve opens. The use of a throttling region can be used in place of a multistage spring to provide a first flow regime in the transition stage of the valve and a second regime in the normal flow stage of the valve. The throttling region could vary in diameter or have a constant diameter, depending on how the throttling region is to be used. In FIG. 1, a constant diameter throttling region is depicted. Conversely, the valve can operate without a throttling region, where the inlet opens up directly to the full flow chamber. It is envisioned that there are many other applications for the valve of the present invention through minor deviations in geometry, material selection and throttling technologies. The concept of the present flow arresting valve can not only be used for residential water, but it can be used for industrial, refinery, marine, municipal, petrochemical, hospital and medical applications. The present invention is ideally suited for any application of a fluid conduit for either liquid or gas that has a requirement to not allow, or to minimize, spills as a result of very low or very high leak rates. Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.