Hydraulic filter assembly with priority valve

Abstract

A filter module assembly utilizes a priority valve installed in a manifold to allow for continuous filtration of hydraulic fluid up to a predetermined flow value and diverts occasional high flow to a secondary circuit. This arrangement provides both a low pressure drop at a high flow condition and structural integrity (1,000,000 impulse cycles from 0 to 6000 psi) while at the same time reducing the weight by as much as 50% from a conventional design approach.

1 . A process for filtering a fluid comprising: 
 (a) sensing a fluid flow rate of a fluid;    (b) passing the entire fluid flow through a first filtering element when the flow rate of the fluid is less than or equal to a predetermined threshold value; and    (c) when the flow rate of the fluid increases above the predetermined threshold value, diverting the amount of fluid above said threshold value away from said first filtering element and through a second, parallel filtering element while the amount of fluid at and below the threshold value continues to pass through the first filtering element.    
   
   
       2 . The process of  claim 1 , further including expelling through a single outlet fluid filtered through said first filtering element and fluid filtered through said second filtering element.  
   
   
       3 . The process of  claim 1 , wherein the first filtering element includes a first porous filter medium and the second filtering element includes a second porous filter medium, and the mean pore diameter of the second porous filter medium is greater than the mean pore diameter of the first porous filter medium.  
   
   
       4 . The process of  claim 3 , wherein at least one of said first porous filter medium and second porous filter medium is pleated.  
   
   
       5 . The process of  claim 3 , wherein at least one of said first porous filter medium and second porous filter medium has a hollow, generally cylindrical configuration.  
   
   
       6 . The process of  claim 5 , wherein the first filtering element includes a perforated core and the first porous filter medium is disposed about the perforated core.  
   
   
       7 . The process of  claim 1 , wherein steps (b) and (c) are carried out by using a fluid flow rate responsive valve.  
   
   
       8 . The process of  claim 7 , wherein said valve is not in direct communication with a downstream side of the first filtering element.  
   
   
       9 . The process of  claim 7 , wherein the valve comprises a valve body having a first end and a second end and defining an inlet for fluid flow through said first end, the valve body including a plurality of first circular apertures and a plurality of second circular apertures defined through the periphery of the valve body so as to define, respectively, a secondary outlet in communication with said second filtering element and a primary outlet in communication with said first filtering element.  
   
   
       10 . The process of  claim 9 , wherein the valve further includes a piston having a plurality of circular apertures through the periphery thereof and a metering orifice, said piston being coaxial with, and slidably mounted within, the valve body such that, when the fluid flow rate increases above the threshold value, the piston moves relative to the valve body to allow the amount of fluid above the threshold value to be directed away from the primary outlet and through the secondary outlet while the amount of fluid at and below the threshold value continues to pass through the metering orifice to the primary outlet.  
   
   
       11 . The process of  claim 7 , wherein the first filtering element is contained within a filter bowl, the valve and second filtering element are contained within a manifold, and the manifold is coupled to the filter bowl.