Abstract:
A spring-driven guided check valve which eliminates fluttering of the disc as it moves between the open and closed position against a seat. A disc has an integrated guide which slides against a sleeve inside the body of the valve. This configuration only allows linear movement of the seat in a direction towards (and away) from an inlet face without changing the orientation of the disc. The disc is held in a constant orientation and thus cannot shift at an inclined attitude (flutter). Thus, once the valve closes and the disc makes contact with the seat, the entire disc would contact the entire seat at the same point in time because of the parallel orientation of the disc to the contacting surface of the seat.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0001]    The present general inventive concept is directed to a method and apparatus, and directed to a guided check valve. 
       Description of the Related Art 
       [0002]    Spring operated check valves which can be used in high pressure hydraulic systems and in other applications are known in the art.  FIG. 1  is drawing of a prior art thread-in disc type check valve. 
         [0003]    In typical operation, this valve allows flow in one direction, while it prevents flow in the opposite direction. The valve shown in  FIG. 1  consists of a valve body  101 , valve disc  102 , valve seat  103 , and spring  100 . Aperture  111  leads to a spring chamber  104 . Outlet face  110  is the face of the valve on the outlet side (the side of the valve fluid flows out of). Nine holes are shown in the outlet face  110  through which the fluid flows. Inlet face  115  is the face of the valve on the inlet side (fluid flows into the inlet face side when the valve is open, through the valve and out the outlet face side). 
         [0004]    In the absence of any fluid pressure, the valve disc  102  is urged in the closed position against the valve seat  103  by the spring  100 . The mating surfaces of both the disc  102  and the seat  103  are flat lapped in order to provide a metal on metal seal. 
         [0005]      FIG. 2  is a drawing of a cross section of the thread-in disc type check valve in the closed position. In this position, flow through the valve in the reverse direction, from leftward (the outlet face  110 ) to rightward (the inlet face  115 ), is prevented. In actual use, the forward face of the seat of the valve is typically provided with an O-ring to prevent any helical leakage around the threads from bypassing the seat/disc interface. One of the holes  112  is shown which allows fluid to pass through. Note that in the closed position, fluid cannot pass through the entire check valve in either direction, as the seal between the seat  103  and the disc  102  does not allow pass-through (and there is no other pass in the valve to allow such flow). 
         [0006]      FIG. 3  is a drawing of a cross section of the thread-in disc type check valve in the open position. This occurs when the pressurized fluid, acting over the exposed face of the disc  102 , creates a force sufficient to overcome the opposite closing force of the spring. Once the disc is lifted off of the seat, a flow path exists through the valve, from right to left. Fluid can flow out of the hole  112 , which is one of many such holes (see  FIG. 1 ). 
         [0007]    “Disc flutter” is one disadvantage of this type of valve that can occur in certain flow conditions. The unguided disc is vulnerable to rapid motion, or fluttering, in the face of a turbulent flow through the valve, with the valve in a partially opened position. This can occur if the entrance to the valve is immediately downstream of a sudden change in fluid direction, such as after an elbow. This fluttering will cause the hardened disc to strike the valve body and seat at an inclined attitude (reflected in  FIG. 4 ), resulting in very high local stresses, plastic deformation, and wear. Note how the disc  102  is at an angle. Also, frequent valve opening and closing in the face of a non-axial fluid flow, again, for example, caused by placement after an elbow or the like, and at nominal flows near or at the flow rating of the valve, can cause angular impingement of the disc against the body (as the valve is opening), and the seat (as the valve is closing). This again results in very high local stresses at the initial contact point, with resulting plastic deformation and wear. 
         [0008]    The end result is that a disc type check valve operating under conditions conducive to valve disc flutter may experience accelerated wear, and its disc-seat interface may become incompetent in very short order. Disc chatter is another disadvantage of the disc type valve, where, when, at very low flow rates, it ‘chatters’ or rapidly opens and closes. This can cause rapid wear of the seat. 
         [0009]    What is needed is a disc type check valve that overcomes, reduces or eliminates this disc flutter and chatter. 
       SUMMARY OF THE INVENTION 
       [0010]    It is an aspect of the present invention to provide an improved valve. 
         [0011]    These together with other aspects and advantages which will be subsequently apparent, reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which: 
           [0013]      FIG. 1  is drawing of a prior art thread-in disc type check valve; 
           [0014]      FIG. 2  is a drawing of a cross section of the thread-in disc type check valve in the closed position; 
           [0015]      FIG. 3  is a drawing of a cross section of the thread-in disc type check valve in the open position; 
           [0016]      FIG. 4  is a drawing of a cross section of the thread-in disc type check valve undergoing fluttering or angular opening; 
           [0017]      FIG. 5  is a drawing of a valve disc with a guide used in a check valve, according to an embodiment; 
           [0018]      FIG. 6  is a drawing of a cross section of the check valve utilizing the disc with a guide, according to an embodiment; 
           [0019]      FIG. 7  is a drawing of a cross section of the check valve in the open position, according to an embodiment; 
           [0020]      FIG. 8  is a drawing of a cross section of the check valve in the closed position, according to an embodiment; 
           [0021]      FIG. 9  is a drawing of a cross section of the check valve in the open position, according to an embodiment; 
           [0022]      FIG. 10A  is a perspective drawing of an external view of the outlet face of the check valve, according to an embodiment; 
           [0023]      FIG. 10B  is a perspective drawing of an external view of the inlet face of the check valve, according to an embodiment; 
           [0024]      FIG. 11  is a drawing of the check valve in a body, according to an embodiment; and 
           [0025]      FIG. 12  is a drawing of the check valve in a body with an enclosed chamber at the outlet of the valve, according to an embodiment. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
         [0027]    The general inventive concept relates to a disc type check valve (enabling fluid to flow in only one direction but not the reverse direction) which reduces or eliminates the disc flutter problem described above. The check valve described herein can be used in hydraulic power systems although it can also be used as a check valve in any other system as well, such as a gas driven system. The check valve may be preferred for use in hydraulic systems operating in flow environments that are conducive to valve disc flutter and/or applications where the inlet flow is non-axial. However, the check valve would operate in any environment. 
         [0028]    Note that fluid as used herein refers to any type of hydraulic fluid typically used in the art, including a fluid based on any kind of oil, mineral oil, water, water glycol, and any commercially available hydraulic fluid such as SKYDROL, etc. 
         [0029]      FIG. 5  is a drawing of a valve disc with a guide used in a check valve, according to an embodiment. 
         [0030]    A disc  502  has a raised annulus on the posterior surface of the disc  502  which is referred to as a guide  505 . The guide  505  is integrally part of the disc  502  (manufactured as the same piece), although in another embodiment the guide  505  can be manufactured as a separate component and attached to the disc  502 . 
         [0031]      FIG. 6  is a drawing of a cross section of the check valve utilizing the disc with a guide, according to an embodiment. The check valve operates in the manner as illustrated in  FIGS. 1-3  but utilizes the disc  502  with its guide  505 . The disc  502  will make a tight seal with a seat  603  in the closed position. The check valve has a body  601 , hole  612  (out of a set of holes for fluid flow as illustrated in  FIG. 1 ), and an aperture  611  into a control chamber  613 . A spring  600  is located between the body  601  and the disc  502  and the guide  505 , and is guided by the inside diameter of the guide  505 . The spring  600  will naturally push the disc  502  against the seat  603  forming the tight seal, which can open upon sufficient opposite pressure on the disc  502  from fluid flowing from the inlet face  615  towards the outlet face  610 . Of course fluid flowing from the outlet face  610  towards the inlet face  615  will exert pressure on the disc  502  (along with the spring  600 ) to maintain the closed state (tight seal between the disc  502  and the seat  603 ) thereby preventing fluid from flowing in the opposite direction. 
         [0032]    Outlet face  610  is the face which the fluid flows out through (when the valve is in the open position and fluid is flowing through the valve). Inlet face  615  is the face of the valve on the inlet side (fluid flows into the inlet face side, through the valve and out the outlet face side). [ 33 ] A portion of the outside diameter of the guide  505  is in opposition to a corresponding inside diameter of a sleeve  607  on the valve body  601 . This prevents the disc  502  from cocking or fluttering in the valve, and allows only axial movement. In other words, the motion of the disc is straight (or linear) in that the disc  502  does not change its orientation but simply moves along one axis (vector) either forward (closes) or backward (opens). The disc  502  maintains constant orientation throughout its motion. In the closed position, the disc  502  meets the seat  603  uniformly. In other words, the entire disc  502  would contact the seat  603  all at one time and not partially (as in the “flutter” condition illustrated in  FIG. 4 ). The surface of the disc  502  which touches the seat  603  remains parallel to a surface of the seat  603  which contacts the disc  502  during motion of the disc  502 . 
         [0033]      FIG. 7  is a drawing of a cross section of the check valve in the open position, according to an embodiment. 
         [0034]    When opening, remaining open, or closing, the sleeve  607  limits the motion of the guide  505 , thereby only allowing axial motion of the disc  502 . The disc  502  therefore will not impact either the seat  603  when closing, or the body  601  when opening, in an inclined attitude. The area of contact is increased, and localized stresses are reduced as are the rates of wear. When contact occurs between the disc  502  and the seat  603  (in the closed position), the contact is uniform around both the seat  603  and the disc  502  therefore causing uniform wear. Thus, one benefit of the check valve described herein is that it may reduce wear over the prior art check valve. Another benefit of the check valve described herein is the possibility to dampen valve opening and closing. 
         [0035]      FIG. 8  is a drawing of a cross section of the check valve in the closed position, according to an embodiment. 
         [0036]    Note the volume of the control chamber  800 . The control chamber  800  would typically be filled with the medium passing through the valve, for example, hydraulic fluid. A volume equivalent to the difference between the control chamber  800  with the valve in the open and closed positions needs to be evacuated from the control chamber  800  when the valve is open. Conversely, the same volume must be added back to the chamber when the valve moves from the open to the closed position. In another embodiment, the fluid in the control chamber  800  is in communication with the fluid exiting the valve. This fluid is discharged into, and sourced from, the fluid at the exit of the valve. However, the pressure inside the control chamber  800  can be different than the pressure of the fluid flowing through the valve. For example, fluid pressure acting on the forward face of the disc is opposed by the spring, and the pressure of the fluid inside of the chamber acts on the forward area inside the guide. When the valve is opening (particularly rapidly) this pressure can be high. When closing, the pressure will tend to be lower than the pressure on the inlet side of the aperture. Utilizing fluid inside the control chamber  800  is required for proper operation of the valve. 
         [0037]      FIG. 9  is a drawing of a cross section of the check valve in the open position, according to an embodiment. 
         [0038]    Note that the volume of the control chamber  800  in the closed position is larger than the volume of the control chamber  800  when the valve is in the open position (see  FIG. 8 ). 
         [0039]    By varying the size of aperture  611 , the rate of emptying or filling the control chamber  800  may be varied, and thus the rate of valve opening and closing can be controlled. The clearance between the outer diameter of the guide  505  and the inner diameter of the sleeve  607  is a leakage path  900  (typically very narrow compared to the aperture  611 ) where fluid can leak between the inlet side and the control chamber  800 . An optional seal  901  can be placed between the outer diameter of the guide  505  and the inner diameter of the sleeve  607  to eliminate the leakage path  900 . Therefore, by controlling the maximum disc velocity of the disc  502 , the energy of impact may be limited. This also reduces the rate of wear. Certain applications may benefit from slower rates of opening and closing, and thus may find the check valve described herein advantageous. The control chamber  800 , through its dashpot action, also tends to reduce or eliminate valve chatter (the rapid opening and closing of the valve at very low flows with the valve barely open). 
         [0040]    The improved rate of wear offered by the valve described herein offers the possibility to make disc type check valves out of different, softer materials. There are certain applications where it is desirable to employ a valve made out of stainless steel (corrosive fluids are but one example). The typical hardness employed in valve discs and seats of the prior art precluded the meaningful use of stainless steel materials, due to the relative softness of the stainless steels, and the resultant limited lifespan. Valves utilizing the inventive concepts described herein can be made from stainless steel and may have reduced wear over prior art check valves. 
         [0041]      FIG. 10A  is a perspective drawing of an external view of the outlet face of the check valve, according to an embodiment. The outlet face  610  is shown with the set of nine holes (although of course other numbers of holes can be used). In the center of the set of holes is the aperture  611 . 
         [0042]      FIG. 10B  is a perspective drawing of an external view of the inlet face of the check valve, according to an embodiment. During flow operation of the valve, the fluid flows into the inlet face  615 , through the valve and out the outlet face  610 . The disc  502  is shown (note that the side of the disc  502  shown is an opposite side of the disc than the side of the disc which the spring  600  contacts). Note how the sides illustrated in  FIGS. 10A, 10B  are threaded allowing for easy installation of the valve. 
         [0043]      FIG. 11  is a drawing of the check valve in a body, according to an embodiment. The check valve can be inserted inside a body  1102  and can be used as part of a larger hydraulic system. Note the black ovals in  FIG. 11  are seals (seals can be made out of rubber, silicone, or any other suitable material). Fluid flows from an inlet path  1101  through the check valve and out an outlet path  1100 . Note that fluid in the outlet path  1100  can pass through the aperture  611  into the control chamber (and vice-versa). 
         [0044]    Note that fluid as used herein can refer to any type of hydraulic fluid typically used in the art, including a fluid based on any kind of oil, mineral oil, water, and any commercially available hydraulic fluid such as SKYDROL, etc., although any other fluid can be used as well. 
         [0045]      FIG. 12  is a drawing of the check valve in a body with an enclosed chamber at the outlet of the valve, according to an embodiment. 
         [0046]    In one embodiment, the fluid in the control chamber  800  is separately contained from the fluid passing through the valve (e.g., which passes through the opening between the disc  502  and seat  603 ) and is under its own internal pressure (thus fluid in the control chamber  800  is separate and does not pass in or out of the valve in the manner that the fluid flowing through the valve does). 
         [0047]    This can be accomplished by an enclosed chamber (or “can”)  1200  is continuous with the valve body and an orifice  1201  in which matter can pass between the control chamber and the enclosed chamber  1200 . This embodiment can provide both damping action (if the orifice  1201  is small enough), plus additional spring force. In this embodiment, the “fluid” in the enclosed chamber  1200  should be compressible (gas). As such, its pressure will be influenced by temperature. Also shown are seals  1201  (which are all also present in  FIG. 11 ). 
         [0048]    The valve and all parts (with the exception of the spring and seals) should typically be made using hardened steel or other hard material. 
         [0049]    All features described and/or illustrated herein (or the absence of any such feature) can be combined with each other in any combination without limitation. Any combination of feature(s) can be used without limitation with any other combination of feature(s). The illustrations shown herein are exemplary but any illustration can be augmented with any feature described herein or any feature shown can also be removed without limitation. 
         [0050]    The many features and advantages of the invention are apparent from the detailed specification and, thus, it is intended by the appended claims to cover all such features and advantages of the invention that fall within the true spirit and scope of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.