Abstract:
A valve ( 10 ) is provided that combines the features of a solenoid valve and a check valve into a singel combination solenoid check valve. The valve utilizes a first check valve ( 58 ) to allow fluid to flow from the outlet passageway ( 28 ) of the valve to a chamber ( 36 ) above the piston ( 40 ) to ensure that the valve remains closed when the outlet pressure in the valve is greater than the inlet pressure. The valve also utilizes a second check valve ( 42 ) that closes a bleed aperture through the piston when the pressure in the chamber above the piston is greater than the inlet pressure.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 61/150,886, filed Feb. 9, 2009, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates, in general, to a globe valve (solenoid valve) such as the type used in refrigeration applications, and in particular to a valve that combines a solenoid valve and a check valve into a single valve. 
     BACKGROUND 
     In a typical refrigeration system the flow of refrigerant is often controlled through a series of valve groupings. These valve groups (a.k.a. valve trains) consist of individual valves piped together either through bolted flanges, or weld sections of pipe. These valve trains can be made up of any one of a number of different valve types. One such common train consists of a hand valve, solenoid valve, and a check valve coupled together in series. The direction of the refrigerant flow through the valves is the same order as the valves are listed above. The hand valve is used during service situations of the solenoid and check valves. Upon closure of the hand valve all flow of refrigerant is stopped, allowing the solenoid and check valves to be disassembled and serviced. The solenoid valve provides automatic on/off control of the flow of refrigerant during normal operation. The check valve prevents any reverse flow of refrigerant through the solenoid valve. 
     A prior art solenoid valve  110 , model S4W available from Parker Hannifin Corporation, is shown in  FIG. 1 . In the S4W valve  110 , high pressure liquid or gas is stopped at the inlet passageway side  26 ′ of the valve  110  by piston  40 ′. The design of the main piston plug  40 ′ allows inlet pressure to the internal surfaces of the piston  40 ′ and to the top of the piston thus holding the valve closed tightly. The internal portions of the piston are open directly to the inlet flow while pressure to the top of piston is gained through a small bleed hole in the piston (not shown). 
     To open the valve  110 , a coil (not shown) on the valve is energized opening a passage (formed by the combination of  52 ′+ 54 ′+ 38 ′) which allows the pressure contained on top of the piston  40  to bleed off to the outlet (low pressure) passageway side  28 ′ of the valve  110 . The pressure difference across the piston  40  (low on top/high internally) allows the spring  62 ′ to be overcome and the higher inlet pressure to push the main valve piston open—thus opening the valve and allowing flow underneath piston and through the valve seat  30 ′. The valve remains in the open position as long as the coil is energized. Once the coil is de-energized the pressure on top of the piston  40  can no longer bleed to the outlet side of the valve. This causes the pressure on top of the piston to equalize with the pressure in the internal portions of the piston. Equalization is accomplished through the small bleed hole in the top of the piston (not shown). Once the pressure has equalized, the main valve spring  62 ′ can now push the piston  40 ′ closed shutting off the valve port  30 ′. Once again a pressure difference is created between the inlet side  26 ′ of the valve, and the outlet side  28 ′ of the valve, helping to hold it shut tightly. 
     Pilot operated solenoid valves only work in one direction. Should a higher pressure build on outlet side of the valve than on the inlet side, the main piston will be pushed open allowing backward flow through the valve. Thus the need for a separate check valve, such as the prior art CK-1 check valve  210  available from Parker Hannifin Corporation, as shown in  FIG. 2 . Note that the body is reversed with respect to the flow direction. 
     SUMMARY 
     At least one embodiment of the invention provides a valve assembly comprising: a valve housing including an inlet port having an inlet passageway and an outlet port having an outlet passageway separated by an aperture forming a valve port; a piston moveable to open and close the valve port; a solenoid operable to fluidly connect and disconnect a chamber above the piston to the outlet passageway of the valve housing; a first check valve positioned to allow fluid flow from the outlet passageway of the valve housing to the chamber above the piston while preventing flow in the opposite direction; a second check valve positioned to allow fluid flow from the inlet passageway to the chamber above the piston while preventing flow in the opposite direction. 
     At least one embodiment of the invention provides a valve assembly comprising: a valve body having spaced inlet and outlet ports separated by an intermediate valve seat in open communication with the inlet and outlet ports; a piston reciprocable within a bore in the valve body, the piston including a valve member being adapted to sealingly mate with the valve seat; an adapter body secured to an open end of the bore in the valve body; a solenoid assembly operable to open a conduit from the bore in the valve body to the valve outlet; a first check valve providing a conduit from the outlet passageway of the valve housing to the bore in the valve body above the piston while preventing flow in the opposite direction; a second check valve providing a conduit from the inlet passageway to the bore in the valve body above the piston while preventing flow in the opposite direction. 
     At least one embodiment of the invention provides a valve assembly comprising: a valve housing including an inlet port having an inlet passageway and an outlet port having an outlet passageway separated by an aperture forming a valve seat in open communication with the inlet and outlet ports; a piston reciprocal within a bore in the valve body, the piston including a valve member being adapted to sealingly mate with the valve seat, the piston positioned such that the valve opens by moving the valve member of the piston into the inlet passageway and away from the outlet passageway; a biasing member for normally biasing the valve member toward the valve seat; an adapter body secured to an open end of the bore in the valve body; a solenoid assembly operable to open a conduit from the bore in the valve body above the piston to the outlet passageway of the valve; a first check valve positioned in the adapter plate, the first check valve allowing fluid to flow from the outlet passageway of the valve to the bore in the valve body above the piston but preventing fluid flow through the check valve from the valve body above the piston to the outlet passageway of the valve; a second check valve positioned in a portion of the piston, the second check valve allowing fluid flow from the inlet passageway of the valve to the chamber above the piston but preventing fluid flow from the chamber above the piston to the inlet passageway of the valve. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of this invention will now be described in further detail with reference to the accompanying drawings, in which: 
         FIG. 1  is a cross-sectional view of a prior art solenoid valve; 
         FIG. 2  is a cross-sectional view of a prior art check valve; and 
         FIG. 3  is a cross-sectional view of an embodiment of the combination solenoid check valve in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     An embodiment of the present invention is shown in  FIG. 3  as a combination solenoid check valve assembly  10 . The valve assembly  10  comprises a valve body housing  20  having an inlet  22 , an outlet  24 , an inlet passageway  26 , an outlet passageway  28  and a through port  30  (also referred to as the valve seat), providing a fluid passageway between the inlet passageway  26  and the outlet passageway  28 . The valve assembly  10  also comprises a piston  40  reciprocable within a bore  35  in the valve body housing  20  which includes a valve member  44  being adapted to sealingly mate with the valve seat  30  to open and close the valve  10 . The piston  40  is positioned such that the valve  10  opens by moving the valve member  44  of the piston  40  into the inlet passageway  26  and away from the outlet passageway  28  (similar to the prior art valve of  FIG. 1  and opposite the prior art valve of  FIG. 2 ). The piston  40  also includes a bleed hole check valve  42  which allows fluid to bleed from the inlet passageway  26  to the portion of the bore  35  above the piston  40  which is also referred to herein as the chamber  36  above the piston  40 . An adapter plate  50  is attached to the open bore end of the housing  20 . The adapter plate  50  has a first and second conduit connecting the chamber  36  in the housing  20  and the valve outlet passageway  28 . The first conduit is formed by the combination of a first passageway  52  from chamber  36  above the piston  40  and a second passageway  54  which is fluidly connected to a passageway  38  in the housing  20  that leads to the outlet passageway  28 . The first passageway  52  and the second passageway  54  are fluidly connected and disconnected by a solenoid valve  60 . The second conduit is formed by the combination of the first passageway  52  and a third passageway  56  which is fluidly connected to the passageway  38  in the housing  20  that leads to the outlet passageway  28 . The first passageway  52  and the third passageway  56  are fluidly connected regardless of whether the solenoid is on or off as these passageways effectively bypass the control of the solenoid valve  60 . The second conduit includes a check valve  58  shown positioned at an end of the by-pass passageway  56  which allows fluid to flow from the outlet passageway  28  to the chamber  36  above the piston  40 , but prevents fluid flow in the opposite direction. 
     The operation of the valve  10  is controlled by the solenoid valve  60 . When the solenoid valve  60  is energized, fluid is allowed to flow from chamber  36  above the piston  40  to the outlet passageway  28  (low pressure) side of the valve  10 . The pressure difference across the piston  40  (low on top/high internally) allows a spring  62  force to be overcome and the higher inlet pressure to push the piston  40  away from the seat  30  and open the valve  10 . The valve  10  remains in the open position as long as the solenoid  60  is energized. Once the solenoid  60  is de-energized the pressure on top of the piston  40  in chamber  36  can no longer bleed to the outlet passageway  28  as the first conduit is blocked by the solenoid valve  60  and the second conduit is blocked by the check valve  58 . The bleed hole check valve  42  in the piston  40  opens and allows the pressure on top of the piston  40  in chamber  36  to equalize with the pressure in the internal portions of the piston  40 . Once the pressure has equalized, the main valve spring  62  can now push the piston  40  closed shutting off the valve port  30 . Once again a pressure difference is created between the inlet passageway  26  and the outlet passageway  28 , helping to hold it shut tightly. This operation of the valve is similar to the operation of the prior art valve  110  of  FIG. 1 . 
     In the prior art valve  110 , if the outlet passageway  28 ′ is at a pressure higher than the inlet passageway  26 ′, the fluid pressure would simply lift the piston  40 ′ away from the valve port  30 ′. In the valve  10  as shown in  FIG. 3 , the check valve  58  and the second conduit formed by the combination of the first passageway  52  and the third passageway  56  (which is fluidly connected to the passageway  38  in the housing  20  that leads to the outlet passageway  28 ) allow the valve  10  to automatically prevent fluid flow from the outlet passageway  28  to the inlet passageway  26 . The check valve  58  is oriented to allow high pressure fluid from the outlet passageway  28  to enter the chamber  36  above the piston  40  which forces the piston  40  to move into a valve closed position against the valve seat  30 . The high pressure in the chamber  36  above the piston  40  holds the piston  40  in a closed position. When the pressure in the chamber  36  is greater than the pressure in the inlet passageway  26 , the bleed hole check valve  42  prevents fluid flow from the chamber  36  to the inlet passageway  26 . 
     With the design of the valve  10 , any high pressure build up on the outlet side of the valve  10  is utilized to hold the valve shut, versus letting it flow backwards through the valve  10 . The concept is the same as that used to hold the valve shut during normal operation; utilize pressure to hold the valve shut. Being able to utilize the high pressure on the outlet side of the valve eliminates the need for a separate check valve. 
     The key to making this valve work is in two small pilot flow check valves  42 ,  58  inside the valve  10 . These small pilot flow check valves comprise a metal orifice or seat, and a small PTFE ball. Pressure or flow either pushes the PTFE ball out of the way and allows passage of the fluid or gas, or pushes it back against the seat, closing the passage. 
     One of these passages (formed by the combination of first passageway  52 , third passageway  56  and passageway  38 ) connects the chamber  36  on top of the piston  40  to the outlet passageway side  28  of the valve  10 . During normal operation the higher pressure on top of the piston  40  pushes the PTFE ball of check valve  58  against the seat, closing this passage. This prevents the valve  10  from leaking when in the closed position. If an abnormal high pressure is experienced on the outlet side  28  of the valve  10 , the same PTFE ball of check valve  58  is pushed off the seat allowing the pressure to be applied to the top of the piston  40 , thus holding it shut. The other PTFE pilot flow check valve  42  is installed in the small bleed hole in the top of the piston  40 . During normal operation this pilot flow check valve  42  allows passage from the internal portion of the piston  40  to the chamber  36  on top of the piston  40  to allow pressure equalization. When the valve experiences a high pressure on the outlet side and the first pilot flow check valve  58  opens, the check valve  42  in the top of the piston  40  closes to prevent leakage through to the inlet side  26  of the valve  10 . 
     These two small pilot flow check valves  42 ,  58  working in conjunction allow the main solenoid valve&#39;s piston plug assembly to act as a check valve, stopping any flow backwards through the valve  10 . The combination of the solenoid valve and the check valve into a single valve  10  can save in manufacturing costs, inventories, additional welds for two components, etc. 
     Although the principles, embodiments and operation of the present invention have been described in detail herein, this is not to be construed as being limited to the particular illustrative forms disclosed. They will thus become apparent to those skilled in the art that various modifications of the embodiments herein can be made without departing from the spirit or scope of the invention.