Abstract:
An umbrella valve includes an elastic cap, and an elastic stem formed integrally with the cap, having a center hollow portion, having an enlarged hollow portion proximate the cap, and having a bottom. The valve has a needle having an enlarged head at a proximal end thereof for being snugly secured in the enlarged hollow portion of the stem, having a lower lateral hole in a distal portion, having an upper lateral hole proximate the bottom of the stem, and having a lengthwise center passageway connecting the upper and lower lateral holes. A method includes providing a needle for being snugly secured in one of a plurality of elastic caps, the needle having a lengthwise center passageway connecting upper and lower lateral holes. The method includes selecting a cap from among the plurality of elastic caps by determining opening pressure factors.

Description:
BACKGROUND 
   1. Field of the Invention 
   The invention relates to apparatus, systems, and methods for pressure relief through an orifice and, more particularly, to an umbrella type check valve. 
   2. Background of the Invention 
   There are many applications where it is desirable to provide a pressure relief at a particular location. For example, an automotive application may utilize a crankcase breather valve for ventilation and pressure control in an internal combustion engine while also controlling the direction of flow of fluids, pressure, contaminants, etc. Other examples of pressure relief and flow control may be found in automotive as well as medical, appliance, manufacturing process, pumps, and other areas of technology. 
   An umbrella type check valve is known. Typically, such a valve has a spherical surface that substantially conforms to the contour of the underside of the check valve. The valve is formed of an elastic material so that the spherical surface returns to its nominal shape after being temporarily deformed. The spherical ‘cap’ is typically formed along with a plug or stem that is inserted into an orifice for securing the cap in a position that ‘seats’ against a mounting surface. When the pressure adjacent the orifice becomes large enough, the pressure passes to the underside of the cap and causes the cap to lift off the mounting surface, thereby releasing the pressure to the outside. After releasing the pressure, the elastic cap returns to its seated position on the mounting surface. 
   However, such umbrella check valves require that holes be drilled or otherwise machined in a plug portion of the valve or in the adjacent mounting surface, in order to provide a pathway for passing the pressure from beneath the plug to the underside of the cap. This machining is expensive, resulting in a higher cost and longer manufacturing time for the umbrella valve. In addition, the extra holes in the plug or mounting surface may result in impurities entering the holes thereby defeating a one-way function of the umbrella valve. Additional related problems exist for conventional umbrella valves. 
   OBJECTS OF THE INVENTION 
   It is an object of the invention to provide an improved umbrella valve overcoming some of the problems and shortcomings of the prior art, including those referred to above. 
   Another object of the invention is to provide an improved structure for masking a hole, whereby a possibility of breach of the masking structure is reduced. 
   Another object of the invention is to provide an umbrella check valve with a self-cleaning ability. 
   Still another object of the invention is to provide a modular umbrella valve system where component parts may be changed to accommodate different opening pressure factors of a particular use. 
   Yet another object of the invention is to provide a modular umbrella valve system where component parts may be changed to accommodate size requirements of a particular application. 
   Another object of the invention is to provide an umbrella valve that is easier to manufacture compared with prior art devices. 
   An additional object of the invention is to provide an umbrella valve that requires less machining during its manufacture. 
   Another object of the invention is to provide an umbrella type pressure check valve that may obviate a need to drill holes in an accompanying object receiving pressure relief. 
   Yet another object of the invention is to provide a modular umbrella valve system where a degree of modularity may be selected for a particular application. 
   How these and other objects are accomplished will become apparent from the following descriptions and drawing figures. 
   SUMMARY 
   According to a first aspect of the invention, an umbrella valve includes an elastic cap, an elastic stem formed integrally with the cap, having a center hollow portion, having an enlarged hollow portion proximate the cap, and having a bottom, and a needle having an enlarged head at a proximal end thereof for being snugly secured in the enlarged hollow portion of the stem, having a lower lateral hole in a distal portion, having an upper lateral hole proximate the bottom of the stem, and having a lengthwise center passageway connecting the upper and lower lateral holes. 
   According to another aspect of the present invention, a modular umbrella valve system includes a plurality of elastic caps each having a radial shaped portion and an outer edge portion, the outer edge portion being formed along a mating plane, the elastic caps also each having a stem portion normal to the mating plane, each stem portion having a recess of a first size, and a needle having an enlarged head at a proximal end thereof for being snugly secured in the recess of any one of the plurality of elastic caps, the needle having a lower lateral hole in a distal portion, having an upper lateral hole proximate the bottom of the stem portion, and having a lengthwise center passageway connecting the upper and lower lateral holes. 
   According to an additional aspect of the invention, an umbrella valve includes an elastic cap having a sealing surface and having a stem extending from a center portion of the cap in a direction normal to the sealing surface, the stem having a center hollow portion, having an enlarged hollow portion, and having a bottom, a needle having an enlarged head at a proximal end thereof for being snugly secured in the enlarged hollow portion of the stem, having a lower lateral hole in a distal portion, having an upper lateral hole proximate the bottom of the stem, and having a lengthwise center passageway connecting the upper and lower lateral holes, and a plug adapted for receiving the needle and stem. 
   According to a further aspect of the invention, a method of customizing an umbrella valve includes providing a needle having a head at a proximal end thereof for being snugly secured in a recess of any one of a plurality of elastic caps, the needle having a lower lateral hole in a distal portion, having an upper lateral hole, and having a lengthwise center passageway connecting the upper and lower lateral holes, selecting an elastic umbrella cap from among the plurality of elastic caps, each elastic cap having the recess of a same size, by determining opening pressure factors including at least one of preload, umbrella skirt thickness, umbrella skirt shape, umbrella skirt diameter, and material used for forming the respective cap. 
   According to an additional aspect of the invention, a method of preparing an umbrella type check valve includes providing an elastic cap, forming an elastic stem integrally with the cap, the stem having a center hollow portion, having an enlarged hollow portion proximate the cap, and having a bottom, and inserting a needle having a head at a proximal end thereof into the stem by snugly securing the enlarged head into the enlarged hollow portion of the stem, where the needle has a lower lateral hole in a distal portion, has an upper lateral hole proximate the bottom of the stem, and has a lengthwise center passageway connecting the upper and lower lateral holes. 
   According to another aspect of the invention, a method includes providing an umbrella valve having an elastic cap, an elastic stem formed integrally with the cap, having a center hollow portion, having an enlarged hollow portion proximate the cap, and having a bottom, and a needle having a head at a proximal end thereof for being snugly secured in the enlarged hollow portion of the stem, having a lower lateral hole in a distal portion, having an upper lateral hole proximate the bottom of the stem, and having a lengthwise center passageway connecting the upper and lower lateral holes, the method also including installing the umbrella valve in an orifice for relieving pressure via the orifice while preventing contaminants from entering the orifice. 
   As a result of the invention, manufacturing of an umbrella valve is simplified by reducing machining or similar steps required for forming the valve. An improved structure for masking a hole reduces a possibility of breach of the mask. This is especially important for processes that include several vulnerable steps such as washing, painting, dipping, etc. A modular system is provided for reducing parts inventory while increasing the ability for on-site customizing of umbrella valves for a particular use. Providing functional advantages in an umbrella type pressure check valve may eliminate a need to drill holes in an accompanying object receiving pressure relief. A modular umbrella valve system may be two, three, or more individual pieces. A stem portion may be formed in any shape so that, for example, a two piece structure may be quite useful for an operation that is only concerned with preventing inflow of contaminants such as during a washing operation. By comparison, using three components, such as by using a plug, allows precision masking to be effected, for example in a painting process. A degree of modularity may be selected for a particular application. 
   Additional advantages and a more complete understanding of the present invention may be derived by referring to the detailed description of preferred embodiments and claims when considered in connection with the figures, wherein like reference numbers refer to similar items throughout the figures. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a three dimensional view of an umbrella check valve according to an exemplary embodiment of the present invention. 
       FIG. 2  is a side view of the umbrella valve of  FIG. 1 . 
       FIG. 3  is a side view of the umbrella valve of  FIG. 1  taken along the line A—A of  FIG. 2 . 
       FIG. 4  is a three dimensional view of a needle portion of the umbrella check valve of  FIG. 1 . 
       FIG. 5  is a side view of the needle of  FIG. 4 . 
       FIG. 6  is a vertical view of a shaft portion of the needle of  FIG. 4  taken along the line B—B of  FIG. 5 . 
       FIG. 7  is a side view of the needle of  FIG. 4  taken along the line C—C of  FIG. 5 . 
       FIG. 8  is a three dimensional view of an elastic cap portion of the umbrella valve of  FIG. 1 . 
       FIG. 9A  is a side view of the cap of  FIG. 8 . 
       FIG. 9B  is a bottom view of the cap of  FIG. 8 . 
       FIG. 10  is a side view of the cap of  FIG. 8  taken along the line D—D of  FIG. 9A . 
       FIG. 11  is a bottom view of an elastic cap used in an umbrella valve according to an exemplary alternate embodiment of the present invention. 
       FIG. 12  is a side cutaway view of a needle used in an umbrella valve according to an exemplary alternate embodiment of the present invention. 
       FIG. 13  shows a plug adapted for receiving an umbrella valve, according to an exemplary embodiment of the invention. 
       FIG. 14  is a side cutaway view of an umbrella valve inserted into a plug that, in turn, is installed in an orifice of an object being masked, according to an exemplary embodiment of the invention. 
       FIG. 15  is a top view of the assembly having a plug and umbrella valve, according to an exemplary embodiment of the invention. 
       FIG. 16  shows a plug adapted for receiving an umbrella valve, according to an exemplary embodiment of the invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIGS. 1–10  illustrate an exemplary embodiment of an umbrella valve  10  according to the invention. Umbrella valve  10  has two component parts, cap  30  and needle  50 . 
   Cap  30  is formed of an elastic material, for example, nitrile, viton, fluorosilicone, neoprene, ethylene propylene (EPDM), silicone, hydrogenated nitrile, butyl, fluorocarbon, polyisoprene, epichlorohydrin, chloroprene, polyurethane, styrene-butadiene, polyacrylate acrylic, and others. A preferred embodiment uses silicone in forming a cap for masking a hole during manufacturing processes and is described further below. Cap  30  has a round mushroom or saucer type shape for a main portion  31 . This cap shape may alternatively be formed with a shape that conforms to that of a mating surface, or an other umbrella shape may be used for a particular application. The outer periphery of the main portion  31  has a sealing surface  32  with a flat face, with a tapered profile, with a rounded sealing edge, or with a shape accommodating a particular sealing application. For example, a pressure drop across valve  10  may be controlled by selecting a cap with a particular thickness of its sealing surface  32 . In this example, a radius R of the end of sealing surface  32 , as shown in  FIG. 10 , is ten mils. 
   Cap  30  is formed with an integral stem portion  33  that extends from a bottom portion of cap  30  at a center thereof. Stem  33  has a round cross section with a central core  34 . In this example, a lower portion  35  of central core  34  has a diameter of two millimeters, and an end portion  36  of central core  34  has a diameter of five millimeters. The stem  33  and the center of main portion  31  are adapted for receiving needle  50  in the central core  34 . The body  38  of stem  33  may be vertical, as shown, may have a tapered “stopper” shape, may have external threads, etc. In addition, cap  30  may be formed to function as a pull plug by having a grip portion (not shown) for quick removal of umbrella valve  10 . 
   Needle  50  in this example has a head  51  with a diameter of five millimeters and a long cylindrical body  52  with an outside diameter of two millimeters. The shapes and sizes of portions of the central core of cap  30  conform to the shapes and sizes of the corresponding portions of needle  50 . Therefore, when needle  50  is inserted into cap  30 , the head  51  and cylindrical body  52  of needle  50  snugly fit, respectively, in the corresponding end portion  36  and lower portion  35  of the central core  34  of cap  30 . Needle  50  is preferably formed of a rigid material such as stainless steel, so that it may be easily inserted into or removed from cap  30  by temporarily deforming the elastic material of cap  30 . A use of stainless steel has advantages such as resistance to oxidation and durability. Such a needle may be re-used for a large number of installations into and removals from various caps. Metals such as aluminum and others, rigid plastic such as PVC, semi-rigid (high durometer) elastomer or rubber, or composite materials may alternatively be used for forming needle  50 , depending on a given application. A needle may be have various shapes, including having a tapered portion, having threads for being installed in a threaded receptacle, etc. 
   Needle  50  has an air passage  53  in the core of cylindrical body  52 . In this example, air passage  53  is defined as the inside diameter of the cylindrical body  52  and has a dimension of 1.5 millimeters. The air passage extends between head portion  51  and tip portion  54  of needle  50 . Head  51  and tip  54  are each solid portions. A lower lateral hole  55  extends through needle  50  proximate the tip portion  54 . An upper lateral hole  56  extends through needle  50  proximate the head portion  51 . In this example, the height h of the flange portion of head  51  of needle  50  is 0.5 mm, and the combined length l of the remainder of needle  50  is fifteen millimeters. The distance between upper lateral hole  56  and lower lateral hole  55  is ten millimeters. Tip  54  has a beveled portion  57  and a straight portion  58 . Beveled portion  57  is formed with an included angle α of, for example, forty degrees. In this example, the radius r of tip portion  54  is a maximum of 0.1 mm. 
   When needle  50  is inserted into cap  30 , the upper lateral hole  56  is aligned on each side of needle  50  with corresponding exit holes  37  formed in stem portion  33  of cap  30 . The exit holes  37  are at least as large as upper lateral holes  56  so that the flow through holes  56  is not impeded. As shown, for example, a break  39  may result in the bottom  44  of stem  33  when needle  50  is inserted into cap  30 . Alternatively, depending on a shape of cap  30 , it may be possible to locate the upper lateral hole  56  at a position below the bottom  44  of stem portion  33 . 
   By way of example, an umbrella check valve may be used in a powdercoating, electrocoating, electroplating, chemical wash, or any other surface treatment operation for masking an orifice of an object to be painted, coated, plated, washed, etc. Such a valve may be used when a pressure is created inside the object as a result of subjecting the object to high temperatures. If a simple masking plug were used, it may pop out due to the pressure, resulting in a breach of the mask and intrusion of paint and other impurities into the orifice. By utilizing a venting mask device such as an umbrella type check valve, the pressure is passed from the orifice into the volume of space underneath the cap of the umbrella valve and, when the pressure exceeds a threshold, it causes the elastic cap to lift off the surface of the object, releasing the pressure to the outside. When the pressure is released, the cap returns to its seated position on the mounting surface. In such a manner, the umbrella valve acts as a one-way valve. It is noted that powdercoating is essentially a dry process, while other processes may involve liquid immersion. The valve of the invention is intended to be used in either a dry or a liquid type process. 
   Conventional umbrella valves provide a pathway for the pressure to the underside of the cap by machining holes into a plug portion of the umbrella valve or by a similar use of a vent hole drilled into the object itself. The present inventors have determined that a much simpler construction of an umbrella valve results from the modular system disclosed herein. For example, a user of umbrella check valves may re-use needle  50  while changing caps  30  for particular applications. The user may order new caps  30  for particular applications without a need to re-order the needle portions  50 . The supplier of the umbrella valves saves time and money in producing the valves by eliminating the machining of the holes in the plug portion. 
   In addition, the present inventors have determined that there are tremendous advantages, such as large cost savings, derived from utilizing plugs that are reusable several times. Conventional plugs may pop out at inconvenient times, such as while a host product is being processed along a continuously conveyored bake oven. In such a case, when a plug pops out, it is usually no longer usable since it may end up sitting on an oven floor baking beyond its useful life. Therefore, a huge savings may result by, for example, ensuring ten or more uses for a valved plug compared with one use for a standard stopper. 
   Umbrella valves may be precisely designed to open and close at certain pressures. For example, opening pressures may be varied, inter alia, according to the modulus of elasticity, or stiffness, of the material used in forming the cap, according to the amount of preload on a relaxed (non-pressurized) cap, according to the effective flow area or volume, according to the type of edge shape for the cap, according to the size of the cap, and according to the thickness of the cap. A typical range of opening pressures for umbrella valves is from approximately 0.1 to 80 kPa, determined by the listed factors. 
   When a manufacturing engineer or technician prepares a masking setup for prepping parts to be baked in a powdercoating operation, she may select a particular cap type according to a measured or calculated internal pressure of the orifice, for example, based on the temperature and time period of the bake. She may then select a material type for a cap, a diameter and thickness of the cap, a preload, etc. She may then select a cap having a stem diameter and shape for the particular orifice to be masked. A shape of the stem portion of a cap can include various protrusions, have a different length, etc. After selecting the proper cap for the given masking location, she may insert a needle  50  into the selected cap for subsequent installation into the given orifice. 
   When umbrella valve  10  is inserted into the given orifice, a pathway is created from inside the orifice through lower lateral hole  55 , through air passage  53 , through upper lateral hole  56 , and into the space between the mounting surface and the underside  45  of cap  30 . This pathway allows the pressure from inside the orifice to equalize with the pressure under cap  30 , so that when the pressure goes above a threshold, an edge of cap  30  lifts off the mounting surface, releasing the pressure. After releasing the pressure, cap  30  reseats itself on the mounting surface thereby preventing backflow of contaminants into the valve. 
   Umbrella valve  10  effects improved protection against unwanted intrusion of foreign material into the orifice being masked. By providing lateral pressure pathways at the stem portion  33  of umbrella valve  10 , it is less likely that foreign materials will violate the mask, compared with conventional umbrella valve structures that provide pressure relief pathways as vertical holes at a distance from a center of the umbrella valve. For example, valve  10  may be used for preventing contaminants such as paint from passing through or around valve  10  and entering an orifice being masked. In addition, gaskets or similar objects may be used as secondary seals for assuring that foreign materials do not violate the sealing of an orifice. For example, a gasket (not shown) may be placed around the cylindrical portion of needle  50  to form a sealing between a middle portion of needle  50  and an interior wall of the orifice. This will insure that the above-described pressure pathway of umbrella valve  10  is the only possible path and will provide extra precision in pressure control. Umbrella valve  10  may be provided with a stem portion dimensioned and configured as a plug for engaging in a sealing relationship with a target orifice. Such additional sealing measures may not be required to protect against violation of a mask during a particular process being performed, but may offer additional quality control, for example, when there is a possibility that handling or other event between process steps may risk intrusion of foreign matter such as the umbrella valve getting bumped when the host object is being moved from a cleaning area to an oven area. 
   It is noted that a stem portion such as stem  33  may be formed in any desired shape. For example, stem  33  may be formed as a plug having a tapered shape, threads, an enlarged lower portion, etc. Stem  33  may optionally be formed in multiple pieces for implementing modularity and reusability, as discussed further below. It is noted that a modular umbrella valve may be two, three, or more individual pieces. Since a stem portion may be formed in any shape, a two piece structure is possible. Such a structure may be quite useful for an operation that is only concerned with preventing inflow of contaminants, for example during washing. By using three components, such as by using a plug, precision masking may be effected, for example in a painting process. 
   As shown by way of examples in  FIGS. 13–16 , umbrella valve  10  may be part of a system that includes a separate plug  80  that, in turn, may be installed into the target orifice  88  in object  89  by twisting, pushing, screwing, etc. Stem  33  and needle  50  may respectively be inserted into center holes  85 ,  81  of an already-installed plug  80  or, alternatively, needle  50  and stem  33  at bottom portion  44  may be installed in plug  80  before inserting plug  80  into an orifice  88 . Such a system provides an additional level of modularity. For example, plugs of different shapes and sizes may each have same size center holes  85 ,  81  for receiving stem  33  and needle  50 . The center holes  85 ,  81  of plugs  80  each are formed so that the upper lateral hole  56  and lower lateral hole  55  are not blocked when the three components  33 ,  50 ,  80  are assembled. Shaft  50  is chosen to be long enough so that lower lateral hole  55  is below a bottom surface  82  of plug  80 . Plug  80  may be a stopper, threaded, etc., or may be formed, for example, by pouring a resin material into an orifice and curing the resin. Center holes  85 ,  81  for receiving stem  33  and needle  50  may be formed by placing a center post in the orifice prior to pouring the resin, by punching, by a later hole forming process, etc. Similarly, stem  33  and needle  50  may be directly secured into an orifice by addition of a poured resin. 
   In another embodiment, plug  80  may be formed without center hole  85 , as shown by example in  FIG. 16 . In such a case, bottom portion  44  of stem  33  either rests on a top portion  84  of plug  80  or is displaced a distance above top portion  84 . Valve  10  may be snugly secured in plug  80  by the fit of needle  30  in hole  81 , thereby eliminating a need for hole  85 . 
   An assembly that includes plug  80  provides a masking device suitable for precision masking of orifice  88  while providing pressure relief and preventing contaminants from entering orifice  88 . A release of pressure at outer edge portion  32  will not interfere, for example, with paint being sprayed onto a top surface of host object  89 , and a dimension of cap  30  is independent of a size of orifice  88 . For example, the circumference of cap  30  may be chosen for related pressure relief properties, while a plug  80  may be chosen to precisely fit an orifice  88  to be masked. 
   Plug  80  may be inserted into orifice  88  without regard to strain on included valve  10 , especially in a configuration having center hole  81  and not having a hole  85 . In such a case, for example, a metal needle  50  is resistant to being deformed and, as a result, valve  10  may be reused many times since it is undamaged by insertion of plug  80  into orifice  88 . Slight damage to or deformation of plug  80  from insertion into orifice  88  is also of minor consequence because a subsequent use of plug  80  merely involves reseating in a different orifice  88 . Therefore, component parts  10  and  80  are reusable many times, providing a large cost savings. A plug  80  may be discarded and valve  10  reused many times. A strong grip is formed between needle  50  and plug  80 , so that the valve  10  may be gripped and pulled from a plug  80 . A tool or other device may alternatively be used for installing or removing a valve  10  to/from a plug  80 . 
   While needle  30  is not limited to being formed by any particular material, use of a metal such as stainless steel has an advantage in that when umbrella valve  10  is being used for masking an orifice of an object during a heating process in manufacturing, a stainless steel needle will conduct the heat and act in a self-cleaning manner. For example, when umbrella valve  10  is used for masking a hole in an object during a baking period of a powder coating type painting process, the stainless steel needle  50  will be heated and such heat sourcing will act to expel any foreign material that could possibly enter needle  50 . Needle  30 , especially head  51 , may be cemented to stem  33  by using any suitable adhesive, for example, epoxy, cyanoacrylate, urethane, etc., depending on the adhesive&#39;s resistance to high temperature, chemicals, and other environmental, cost, availability factors, etc. 
   Other rigid, non-deformable materials may alternatively be used in forming a needle for use with the present invention. While it is also possible to use deformable materials such as silicone in forming needle  50 , such may risk collapsing or clogging of a pressure pathway or reducing advantages of a rigid structure. The umbrella valve  10  may be formed using various rigid sections having one or more layers of different materials, including woven or braided layers, including materials such as fiberglass, block copolymer amide or similar, or other types of nylon, chemical or high temperature resistant materials, or any other polymers and extrudable materials, etc. 
     FIGS. 11–12  show a cap  130  and needle  150  in an alternate embodiment of the invention. For ease of correctly aligning exit holes  137  of a selected cap  130  with upper lateral hole  156  of a needle  150 , the modular umbrella valve system uses a keying structure. A projection  161  is formed along an upper portion  160  of cylindrical body  152  to act like a key. A corresponding recess  141  is formed in stem portion  133  of cap  130 . When needle  150  is being inserted into cap  130 , a technician inserts key  161  into recess  141  while installing head  151  of needle  150  into end core portion  136  of stem  133 , to assure that exit holes  137  of cap  130  are precisely aligned with upper lateral hole  156  of needle  150 . 
   While the principles of the invention have been shown and described in connection with specific embodiments, it is to be understood that such embodiments are by way of example and are not limiting.