Abstract:
A mechanical leak arresting valve is disclosed in which fluid through the valve is limited to a range between a predetermined minimum flow rate and a predetermined maximum flow rate, and where both a small or large downstream leak mechanically causes the valve to lock closed. The present invention uses a locking mechanism triggered by a pressure differential resulting from the downstream leak to block the flow of fluid through the valve until the fluid source upstream is stopped. Reduction of the upstream pressure by the stopping of the fluid source automatically resets the valve without further manipulation.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to flow control valves, and more particularly to leak arresting mechanical flow control valves that regulate fluid flow between a minimum flow rate and a maximum flow rate. 
     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. Some valves are mechanical devices that use the pressure in a fluid flow to compress a spring or other resisting member, 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 (or safety) valve which allows a constant fluid flow in a predetermined range, as opposed to a pulse flow. Valves used for this purpose are too numerous to identify, but the present invention includes a new feature not found in the prior art valves, namely, a purely mechanical leak detecting function. That is, a mechanical valve which regulates the fluid flow to maintain a flow rate 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 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 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. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     The present invention is a reliable, mechanical valve which does not rely on any electronics or human interaction to perform its leak arresting function. The leak arresting valve includes a first stage which includes a spring loaded member for limiting the flow rate through the valve to a predetermined range, i.e., between a minimum flow rate and a maximum flow rate. Above a maximum flow rate, a flow arresting element such as a ball, gate, poppet, diaphragm, or other known valve blocking mechanism is driven by the force of the fluid flow resulting in a large pressure differential across the element, into a non-flow position causing fluid flow through the valve to cease. Below the maximum fluid flow rate, the position of the flow arresting element is such that fluid flows by, around, or across the element thereby permitting fluid to pass through the valve. In a second stage of the leak arresting valve, a second flow arresting element is biased in a closed position and requires a minimum flow condition to open the second stage. Below a minimum flow rate the fluid flow is insufficient to open the valve, thereby precluding flow through the valve. Additionally, the second stage is set up such that a locking mechanism will lock the second stage flow arresting element in a closed position upon the occurrence of a small downstream leak, but will open normally under normal operating conditions. The leak arresting function, i.e., the locking of the valve in the closed position, is achieved by the higher pressure upstream, actuating locking members which lock the second stage flow arresting element in the closed position. 
     Under normal start up condition, the difference in the upstream and downstream pressures with reference to the second stage flow arresting element is large. The second stage flow arresting element transitions due to the pressure difference in a rapid manner past the trigger for the locking mechanism before suitable time is given for the trigger to respond. Conversely, under the influence of a downstream leak, the back pressure on the valve is reduced, and a smaller pressure differential across the second stage flow arresting element is present. The pressure differential is ultimately used to actuate the locking mechanism that restricts the linear translation of the flow arresting element. This configuration will exist even after the differential pressure increases within the normal range. Only after the leak condition is corrected can the valve be reset and returned to a normal configuration. Once the upstream fluid flow is terminated, the pressure differential is eliminated through the valve and all leak conditions, whether small or large, can be reset and all locking members are retracted to their original positions. In this manner, the leak arresting valve resets automatically upon the equalization of the pressure, and mechanically detects the presence of a downstream leak. 
    
    
     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 the leak arresting valve of the present invention in the absence of a fluid flow; 
     FIG. 2 is a cross-sectional view of the leak arresting valve of the present invention in the excessive fluid flow condition; 
     FIG. 3 is a cross-sectional view of the leak arresting valve of the present invention in the operable fluid flow condition; 
     FIG. 4 is a cross-sectional view of the leak arresting valve of the present invention in the downstream small leak condition; and 
     FIG. 5 is an enlarged cross-sectional view of the locking channel sleeve of the present invention. 
    
    
     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 cross section of one preferred embodiment of the present invention. A valve body  208  is preferably a brass or stainless steel cast, although the specific material will likely depend on the application, and is annular shaped with female threaded ends  216 , 218 . Threaded end  216  receives a threaded housing  200  forming a first stage flow control chamber, and threaded end  218  receives a threaded housing  220  forming the second stage flow control chamber. Housing  200  has a male threaded end  217  which engages the female threaded end  216  of the valve body  208  to form a fluid tight seal. Similarly, the housing  220  has a male threaded end  219  which engages the female threaded end  218  to form a fluid tight seal. The first stage flow control chamber includes an internal channel  202  which conducts fluid into and through the valve, and the second stage fluid control chamber includes internal channel  222  which is in fluidic communication with the first internal channel  202  and forms the passageway through and out of the valve. Accordingly, internal channel  202  is referred to as the upstream portion of the valve where the fluid enters the valve, and internal channel  222  is referred to as the downstream portion of the valve where fluid exits the valve. 
     As shown in FIG. 1, the first stage flow control chamber includes a flow arresting element  204  such as a gate poppet shown, although any number of flow arresting elements such as balls, cones, etc. are known in the art and may be readily substituted if consistent with the scope of the present invention. Fluid flows around the gate poppet by entering the voids in the cylindrical walls, and the gate poppet will remain in the position shown in FIG. 1 under normal flow conditions. The gate poppet, or flow arresting element  204  is biased by a spring  206  which is supported by the valve body  208  at shoulder  211 . The spring  206  biases the flow arresting element  204  against the shoulder  213  of the housing  200  when the fluid flow is less than the maximum fluid flow for the valve (dictated here by the choice of spring  206 ). Fluid can enter the valve by bypassing the flow arresting element  204  and enter the second stage of the valve. 
     The second stage flow control chamber also includes a flow arresting element  224  such as a gate poppet shown, and as before other known substitutes may be utilized as long as they are consistent with the scope of the present invention. The flow arresting element  224  is biased by a spring  226  which is supported by the housing  220  at shoulder  221 . The spring  226  biases the flow arresting element  224  against the shoulder  223  of the valve body  208  such that, below a minimum fluid flow rate, the valve is closed shut by the seal between the flow arresting element  224  and an annular collar  225  at the sealing interface  229 . 
     The annular collar  250  is retained in the valve body  208 , such that the annular collar  250  is seated against the shoulder  225  and abutting the housing  220 . As shown in more detail in FIG. 5, the annular collar includes narrow capillary channels  252  directed radially from the valve interior and leading to fluid reservoirs  254 . The fluid reservoir is formed by the inner surface of the valve body  208  and a groove or void formed on the outer diameter of the annular collar  250 . Although two sets of capillary channels and reservoirs are shown, there may be more sets circumferentially spaced about the perimeter of the annular channel as required by the specific application. The reservoir  254  has a second fluid channel  279  leading to a column  258  which houses a piston-like apparatus comprising a pin  260 , a washer  262 , and a spring  256 . The column  258  is in fluidic communication with the interior of the valve channel through bleed orifice  264 . 
     As shown in FIG. 1, the fluid circuit comprising capillary channel  252 , fluid reservoir  254 , fluid channel  279 , column  258 , and bleed orifice  264  are all exposed to the same fluid pressure in the static condition, i.e., the downstream fluid pressure. As will be shown, the fluid circuit will also be exposed to the same fluid pressure in the normal operating condition (see FIG.  3 ). When the pressure at the fluid reservoir  254  is the same as the pressure in the bleed orifice  264 , then spring  256  biases the pin and washer (i.e., the pin assembly) out of the interior of the second stage flow control chamber. 
     FIG. 2 illustrates the condition of the valve under what is known as the excess fluid flow condition. As fluid initially enters the valve, it flows around the flow arresting element  204  in the first stage and, if the flow rate is great enough, forces the second stage flow arresting element  224  to recess thereby opening the second stage of the valve. However, if the flow rate exceeds the maximum design flow rate, the pressure exerted on the flow arresting element  204  by the fluid flow causes the flow arresting element to recede in the first stage chamber against the force of the spring  206 , collapsing the spring  206 . Above a maximum fluid flow, the flow arresting element completely compresses the spring  206  such that the flow arresting element  204  is moved back into the valve until it abuts shoulder  227  of the valve body  208 . At this flow condition, the flow arresting element cooperates with the shoulder  227  of the valve body  208  to close and seal the valve. By choosing the spring  206  accordingly, the first stage flow control chamber can effectively limit the fluid flow rate to values below a preselected maximum flow rate. Because the fluid flow is arrested prior to the second stage flow control chamber, the second stage flow control chamber is unchanged from the no flow condition as shown in FIG.  1 . 
     FIG. 3 illustrates the fluid flow condition through the valve in which the fluid flow rate is steady between the maximum and minimum fluid flow rates as prescribed by the first stage flow control chamber and second stage flow control chamber, respectively. The pressure on the flow arresting element  204  due to the fluid flow is not so great as to position the flow arresting element against shoulder  227 . Thus, the flow arresting element  204  resides at its open position permitting fluid to flow around the flow arresting element through the internal channel  202  and into the internal channel  222  of the second stage flow control channel  222 . The fluid flow impinges against the flow arresting element  224  in the second stage, and the flow arresting element  224  is moved against the spring  226 . This condition results in the flow arresting element  224  operating at an open position where fluid flows around flow arresting element  224  and out the valve. This condition occurs when the sealing interface  229  of the flow arresting element  224 , which cooperates with the annular collar to seal the valve in the closed position, recedes past the annular collar  250  thereby allowing fluid to enter the channel  222  of the second stage. With the sealing interface  229  of the flow arresting element still within the annular collar  250 , a seal is formed by the periphery of the sealing interface and the internal wall of the annular collar  250  such that no fluid can flow through the valve. 
     With the flow arresting element translated beyond the annular collar as shown in FIG. 3, it is noted that the fluid circuit which includes the capillary channel  252 , reservoir  254 , the channel  279 , the column  258 , and the bleed orifice  264  (see FIG. 5) are all exposed to the same fluid pressure, to wit, the pressure just upstream of the flow arresting element  224 . Fluid enters through the capillary channel and after a short delay, completely fills the fluid reservoir. The delay is due to the difference in size between the narrow capillary channel and the relatively larger reservoir. Once the reservoir fills completely, the pressure in the valve at the capillary channel is transferred to the column, and specifically on the washers which form a seal with the column&#39;s inner wall. Since the bleed orifice is also in fluid communication with the valve interior, the same pressure will be present on the opposite sides of the washers, negating any effect that the fluid pressure has on the pin assembly. In this situation, the spring  256  acts to bias the pin assembly out of the channel permitting uninhibited movement of the flow arresting element through the channel as the fluid flow increases to the desired flow regime. 
     FIG. 4 illustrates the situation in which a downstream leak is present resulting in the automatic locking of the valve, which announces the presence of a downstream leak. If the valve is initially in the static condition, such as that shown in FIG. 1, and a small leak is present far downstream of the valve, the back pressure in the downstream portion of the valve will be reduced due to the leak. The upstream pressure is constant, but the downstream pressure is slowly diminishing as the fluid leaks from the downstream line. The reduction in downstream pressure will communicate to the second stage of the valve, where the equilibrium between the flow arresting element  224  and spring  226  is slowly disturbed. The increasing pressure differential due to the constant upstream pressure and the diminishing downstream pressure causes the flow arresting element to translate gradually from the closed position of FIG. 1 to the open position of FIG.  3 . 
     When the flow arresting element  224  reaches the position as shown in FIG. 4, the pressure at the capillary channel  252  is at the higher upstream pressure, while the pressure at the bleed orifice  264  is at the ever decreasing lower downstream pressure. The higher upstream pressure is communicated to the reservoir  254  and then to the column  258 . This pressure differential operates on the washers to move the pin and washers against the force of the spring  256 , eventually collapsing the spring  256 . In this state, the pin  260  is forced through the bleed orifice  264  and into the chamber where it prevents translation and locks the flow arresting element  224  in the closed position. Furthermore, as long as the leak is present, the pressure in the downstream portion of the valve, i.e. at the bleed orifice  264 , will be less than the pressure in the upstream portion of the valve, i.e. the capillary channel  252  and the pin assembly will act as a locking mechanism to maintain the valve in an closed position. If the fluid flow source is disconnected upstream, thereby allowing the pressure differential across the fluid channel to equalize, the pin assembly will no longer experience a pressure differential and be forced back into the column by the force of the spring  256 . Thus, one can unlock the valve by disconnecting the source of the fluid, which will automatically reset the valve without further handling of the valve. In this manner, the valve can be completely encased and installed in a line of an existing application without the need for accessing the valve or its interior in order to reset the valve. 
     The size of the fluid reservoir  254  in comparison to the size of the capillary channel  252  is chosen to create a delay between the existence of a pressure differential across the flow arresting element  224  and the actuation of the locking mechanism. This avoids the undesired locking of the flow arresting element under normal start up conditions, in which a pressure differential will likely exist as the flow builds up to its normal flow rate. In the normal start up condition, the pressure from the fluid flow will cause the flow arresting element to traverse from the extreme position in FIG. 1 to its open position in FIG. 3 in a rapid manner. During the transition, the flow arresting element  224  will necessarily pass the position it occupies in FIG. 4, allowing fluid to enter the reservoir  254  through the capillary channel  252 . However, if the relationship between the size of the capillary channel and the size of the fluid reservoir is such that the reservoir adequately pressurizes with fluid after several seconds, the flow arresting element will have traversed to the open position before the reservoir can fill with fluid (if spring  226  is selected properly), and thus the locking mechanism is not triggered during normal start up conditions. Only during a slow leak condition in which the downstream leak causes a slow translation of the flow arresting element  224  will the fluid reservoir have enough time to pressurize and actuate the locking mechanism. 
     The operation of the just described invention will be illustrated with an example of an application of the present invention, where the application is that of a domestic washing machine water line. The valve is placed in the line which delivers water to the washing machine, and may be located in a place which is not easily accessible. The spring  206  on the upstream or the first stage of the valve is sized such that when the fluid demand from the washing machine is placed on the valve, if the demand exceeds the strength of the spring there is an automatic closure of the gate poppet. What maintains the seal of the gate poppet to the valve body is the line pressure of approximately 60 psi in this example, acting in a direction which is parallel to the long axis of the valve. 
     The spring which is used for the second stage flow arresting element of the valve is sized such that when the water demand of the washing machine is placed on the valve, for example two gallons per minute, the spring opens immediately. The design of the spring would be such that the flow arresting element would open at a detected pressure differential equal to approximately a one half gallon per minute flow demand. The spring thus offers little resistance in the presence a two gallons per minute flow rate, and the second stage flow control chamber opens quickly under the influence of the requested flow rate. 
     The spring in the second flow control chamber may be a nonlinear spring that has two movement episodes, or two stages. One movement occurs at a very low demand request, such as 0.1 gallons per minute, where the flow arresting element  224  translates only to the point where the capillary channel is exposed on one side of the sealing interface  229  and the bleed orifice exposed in the grooved channel. This movement allows the locking mechanism to actuate. A second movement would occur at, for example, 0.5 gallons per minute, allowing the flow arresting element to be fully open from that initial flow rate to the desired flow rate. 
     In addition to a two stage spring design just described, the second stage spring design could alternatively be designed to have a resistance that gradually and continuously increases in stiffness to deflection. Unlike the step function of the two step spring, the continuous nonlinear spring increases in stiffness as it is compressed. Both types of these springs would be sufficient to allow the pressurization of the fluid reservoir with the upstream water pressure, and thereby actuate the locking mechanism. The requirements of the springs that are used in the columns  258  are more stringent than springs  206  and  226  in that when they are exposed to a zero pressure differential across the locking pin the stiffness of the spring is sufficient to retract the pin. It is desirable to have a minimal amount of friction between the pin and the walls of the bleed orifice, and a material such as a low friction polymer is a good choice for the pin material which contacts the wall of the pin column. 
     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 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.