Filter element shutoff valve
BACKGROUND OF THE INVENTION 
     The present invention relates generally to systems for preventing the loss of fluid from a fluid circuit when a filter element located at a low end of the circuit is removed and more particularly relates to an automatic filter element shutoff valve. 
     In the past, when a filter element was removed from a low point in the fluid circuit, two manual valves, one on the inlet passage and one on the outlet passage, had to be closed in order to prevent fluid from being drained or siphoned out of the fluid circuit. When only one valve was closed, fluid would drain or siphon from the other passage resulting in a loss of fliud from at least a portion of the fluid circuit. 
     Further, when the new filter was put into place, it was necessary to remember to manually open both valves to avoid causing a catastrophic failure in other portions of the fluid circuit. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a valve which shuts off both the inlet and outlet passages automatically during the normal operation of removing the filter element. 
     The above and additional advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic illustration partially in section of the fluid system embodying the present invention; and 
     FIG. 2 is a cross-sectional partial view of the valve of the present invention in an alternate position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1, therein is shown a fluid circuit which includes a reservoir 10 connected by an inlet passage 12 to an automatic filter element shutoff valve 14 with an attached filter element 16. The shutoff valve 14 is further connected to an outlet passage 18 which is connected to the inlet of a conventional fluid pump 20. The pump 20 supplies fluid to various functions generally designated by the numeral 22 which could be either oil or coolant utilizing functions. The functions 22 are connected to return fluid back to the resevoir 10. 
     In an internal combustion engine (not shown) which is where the shutoff valve 14 is generally used, the shutoff valve 14 is disposed in an engine block 24. 
     The shutoff valve 14 includes a poppet valve bore 26 which is positioned perpendicular to a planar sealing surface 28 on the engine block 24. The poppet valve bore 26 is connected to the sealing surface 28 by an outwardly inclined valve seat 30. 
     The inlet passage 12 is connected to the poppet valve bore 26 adjacent to the valve seat 30 and adjacent thereto is an O-ring seal 34. Adjacent to the inlet passage 12 and distally spaced from the sealing surface 28 is a pin hole 36 into which a dowel pin 38 is inserted. The outlet passage 18 is connected to the poppet valve bore 26 adjacent to the pin hole 36. 
     A poppet valve 40 is slidably disposed in the poppet valve bore 26 and passes through the O-ring seal 34 to permanently block fluid communication between the inlet passage 12 and the outlet passage 18. The poppet valve 40 includes a through slot 42 through which the dowel pin 38 extends to limit the movement of the poppet valve 40 in the poppet valve bore 26. A poppet sealing surface 48 encircles one end of the poppet valve 40 and is engageable with the valve seat 30 to prevent the flow of fluid therebetween when engaged. A threaded portion 50 is located adjacent the poppet sealing surface 48 and extends past the sealing surface 28. 
     The poppet valve 40 has provided therein a through passage 52 which extends from the threaded portion 50 through to the opposite end of the poppet valve 40 where it is blocked by a poppet cap 54. The through passage 52 has connected thereto outlet ports 56 which are located between the poppet cap 54 and the slot 42. The outlet ports 56 connect the through pasage 52 to the outlet passage 18. 
     A poppet spring 58 is disposed in the through passage 52 between the poppet cap 54 and the dowel pin 38 so as to urge the poppet valve 40 into a position where the poppet sealing surface 48 will engage the valve seat 30. On the other side of the dowel pin 38 there is provided a check seat 60 against which a check ball 62 is engageable. Between the check ball 62 and the dowel pin 38 in the through passage 52 there is disposed a check spring 64. The check spring 64 has a predetermined free length such that when the poppet sealing surface 48 is out of engagement with the valve seat 30, the check spring 64 will be out of contact with the dowel pin 38 so as to allow free flow of fluid between the check seat 60 and the check ball 62. When the poppet sealing surface 48 is in engagement with the valve seat 30, the check spring 64 loads the check ball 62 so as to prevent the flow of fluid past the check ball 62 and the check seat 60. 
     The conventional filter element 16 consists of a conventional cylindrical filter casing 66 which contains a concentric filter medium 68. The filter medium 68 separates inlet passages 70 from an outlet passage 72 which is concentric with the filter casing 66. The outlet passage 72 is provided with a threaded portion 74 which is engageable with the threaded portion 50 of the poppet valve 40. Encircling the inlet passages 70 and disposed between the filter casing 66 and the sealing surface 28 is a planar filter seal 76 which is engageable against the sealing surface 28 to prevent the leakage of fluid therebetween. 
     In the normal operating position as shown in FIG. 1, the filter casing 66 with seal 76 abuts the engine block 24. With the filter seal 76 in sealing engagement with the sealing surface 28, and the dowel pin 38 abutting the top of the slot 42, the poppet sealing surface 48 will be pulled out of engagement with the valve seat 30. 
     With the pump 20 in operation, fluid is drawn from the reservoir 10 through the inlet passage 12 to pass between the poppet sealing surface 48 and the valve seat 30 to enter the inlet passages 70 of the filter element 16. The fluid is filtered by the filter medium 68 and is drawn out of filter element 16 through the through passages 52. As shown, the check spring 64 is free of the dowel pin 38 so as to allow free flow of fluid between the check seat 60 and the check ball 62 and around the dowel pin 38 to the outlet ports 56 and thence to the outlet passage 18 and into the pump 20 and to the functions 22. 
     When the filter element 16 is to be removed, the filter element 16 is rotated so as to cause the disengagement of the threaded portion 74 from the threaded portion 50 of the poppet valve 40. 
     Initially while the filter element 16 is rotated, the filter seal 76 will remain in engagement with the sealing surface 28 until the poppet valve 40 reaches the position shown in FIG. 2. In the closed position, the poppet sealing surface 48 has been drawn into contact with the valve seat 30 by the poppet spring 58 abutting the dowel pin 38. This blocks the inlet passage 12 of the engine block 24 from the inlet passage 70 of the filter element 16. Simultaneously, the check spring 64 has engaged the dowel pin 38 so as to provide a load on the check ball 62 to cause it to seat against the check seat 60 so as to prevent the loss of fluid from the outlet passage 18 through the through passage 52. 
     After the position of the shutoff valve 14 as shown in FIG. 2 has been reached, the filter element 16 may be turned further to separate the filter seal 76 from the sealing surface 28 and to allow removal of the filter element 16. 
     When replacing the filter element 16, the filter seal 76 must first be brought into sealing contact with the sealing surface 28 before the poppet sealing surface 48 will separate from the valve seat 30 and before the check spring 64 will disengage from the dowel pin 38. Further rotation of the filter element 16 causes the shutoff valve 14 to automatically open to again reach the position shown in FIG. 1. 
     While the invention has been described in conjunction with a specific embodiment, it is to be understood that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the aforegoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations which fall within the spirit and scope of the appended claims.