Patent Publication Number: US-2020291836-A1

Title: Cover for oil filter housing of an integrated drive generator

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The subject invention is directed to an oil filter cover, and more particularly, to a removable cover for an oil filter housing of an Integrated Drive Generator (IDG) coupled to a gas turbine engine. 
     2. Description of Related Art 
     Aircraft currently rely upon electrical, pneumatic and hydraulic systems for secondary power generation. A typical electrical system in an aircraft utilizes an IDG coupled to a gas turbine engine to provide fixed frequency power to the power distribution system and to a variety of loads. 
     An exemplary IDG includes a generator, a hydraulic unit and a differential assembly arranged in a common housing. The differential assembly is coupled to a gas turbine engine by way of an input shaft. The rotational speed of the input shaft varies during the operation of the gas turbine engine. The hydraulic unit cooperates with the differential assembly to provide a constant speed to the generator throughout the operating range of the engine. 
     IDGs operate at elevated temperatures. Synthetic oils are used for cooling and lubrication in IDGs, and as a working fluid. In these systems, tiny metallic wear particulates are formed from normal operation. These wear particles are carried by the oil within an oil circuit, and must be removed to maintain the working efficiency and life of the system. 
     For this reason, the oil circuit includes an oil filter located in a housing having an external cover that facilitates installation, removal and periodic replacement of the oil filter. It is desirable to design oil filters to optimize the dirt holding capacity and operational life of the filter. This is typically done by increasing the amount of filter media within the fixed dimensions of the filter cartridge, since the housing that supports the cartridge has dimensions that are immutable due to spatial constraints, especially in the case of an IDG coupled to a gas turbine engine on an aircraft. 
     However, as the amount of filter media within the cartridge is reduced, the pressure drop through the filter cartridge also increases, impacting the efficiency of the system. It would be beneficial therefore, to maximize the amount of filter media in the oil filter without increasing the pressure drop through the filter cartridge. The subject invention provides a solution by way of a uniquely configured cover for the oil filter housing, which is designed to accommodate a filter cartridge that has a greater axial length than the filter housing within which it is accommodated, while remaining within the spatial constraints that permit ready access to and removal of the cover and filter from the housing for routine maintenance purposes. 
     SUMMARY OF THE DISCLOSURE 
     The subject invention is directed to a new and useful cover for an oil filter housing for use with an Integrated Drive Generator (IDG) coupled to a gas turbine engine. The cover includes an elongated body defining an upper end portion and a lower end portion, and it has a central axis extending therethrough, which delineates an axial length of the body. An axial bore extends through the body of the cover from the lower end portion thereof to an interior end wall in the upper end portion thereof for accommodating an axial end portion of an oil filter located within the housing. 
     In accordance with a preferred embodiment of the subject invention, the axial bore of the body has an axial length that is greater than 85% of the axial length of the body. 
     More preferably, the axial length of the bore is about 90% to about 94% of the axial length of the body. In an exemplary embodiment of the cover, the axial length of the bore is about 1.57 inches to about 1.58 inches, and the axial length of the body is about 1.67 inches to about 1.70 inches. 
     Furthermore, the axial bore has a diameter of about 1.81 inches, and the body is formed from 2024 aluminum alloy and the upper end portion of the body has a hexagonal engagement surface formed thereon for installing the cover on the housing and for removing the cover from the housing. 
     These and other features of the filter housing cover of the subject invention will become more readily apparent to those having ordinary skill in the art to which the subject invention appertains from the detailed description of the preferred embodiments taken in conjunction with the following brief description of the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those having ordinary skill in the art will readily understand how to make and use the subject invention without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to the figures wherein: 
         FIG. 1  is an illustration of an Integrated Drive Generator (IDG) coupled to a gas turbine engine and having an oil filter housing that includes the cover of the subject invention; 
         FIG. 2  is a perspective view of the cover of the subject invention and the elongated oil filter cartridge removed from the filter housing of the IDG; 
         FIG. 3  is a side elevational view of the perspective view of the cover shown in  FIGS. 1 and 2 ; 
         FIG. 4  is a top plan view of the cover; 
         FIG. 5  is a cross-sectional view of the cover taken along line  5 - 5  of  FIG. 4 ; 
         FIG. 6  is an enlarged localized view of a medial flange portion of the cover taken from  FIG. 3 ; and 
         FIG. 7  is an enlarged localized cross-sectional view taken along line  7 - 7  of  FIG. 1  illustrating the elongated oil filter within the housing enclosed by the cover of the subject invention, and showing the path of fluid flow through the oil filter. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings wherein like reference numerals identify similar structural features, there is illustrated in  FIG. 1  an Integrated Drive Generator (IDG)  10  coupled to a gas turbine engine  12  that employs the new and useful cover  14  of the subject invention. More particularly, as shown in  FIG. 2 , the cover  14  is designed to accommodate an elongated radially pleated oil filter cartridge  16  that has a greater axial length than the filter housing  18  within which it is accommodated, while remaining within the spatial constraints that permit ready access to and removal of the cover  14  and oil filter cartridge  16  from the housing  18  of the IDG  10  for routine maintenance purposes. 
     Referring to  FIGS. 3 through 6 , the cover  14  includes an elongated body  20  defining a central longitudinal axis (L Axis ) and having an upper end portion  22 , a lower end portion  24  and a medial abutment flange  26  that surrounds the periphery of the body  20 . The body  20  of cover  14  is preferably formed from  2024  aluminum alloy or a similar material. 
     The central longitudinal axis L Axis  of the body  20  delineates an axial length (L Body ) of the body  20 . More particularly, as shown in  FIG. 5 , the axial length L Body  of the body  20  of cover  14  is about 1.69 inches to about 1.72 inches. As best seen in  FIG. 4 , the upper end portion  22  of the body  20  of cover  14  has a hexagonal engagement surface  28  formed thereon for installing the cover  14  on the housing  18  and for removing the cover  14  from the housing  18  using a hand tool. 
     The lower end portion  24  of the body  20  of cover  14  has a helical thread formation with a standard pitch for threadably engaging the housing  18 , as best seen in  FIG. 3 . The medial abutment flange  26  of the body  20  of cover  14  is best seen in  FIG. 6 . It is adapted and configured to abut against the outer edge surface of the filter housing  18  of the IDG  10  when the cover  14  is threadably engaged to the housing  18 , as best seen in  FIG. 7   
     Referring to  FIG. 5 , the body  20  of the cover  14  has axial bore  30  that extends through the body  20  from the lower end portion  24  to an interior end wall  32  in the upper end portion  22  for accommodating an axial end portion of the oil filter cartridge  16  located within the housing  14 . The axial bore  30  of body  20  has an axial length (L Bore ) of and an inner diameter D Bore . The axial length L Bore  of the bore  30  is about 1.57 inches to about 1.58 inches and the inner diameter D Bore  of the bore  30  is about 1.81 inches. 
     In accordance with a preferred embodiment of the subject invention, the axial length L Bore  of the bore  30  of body  20  is greater than 85% of the axial length L Body  of the body  20 . More preferably, the axial length L Bore  of the bore  30  of body  20  is about 90% to about 94% of the axial length L Body  of the body  20 . In sum, in an exemplary embodiment of the cover  14 , the axial length L Bore  of the bore  30  of body  20  is about 1.56 inches to about 1.59 inches, and the axial length L Body  of the body  20  is about 1.69 inches to about 1.72 inches. 
     Referring now to  FIG. 7 , when the oil filter  16  is installed in the housing  18  of the IDG  10 , the end portion of the oil filter  16  advantageously fits within the axial bore  30  of the body  20  of the cover  14 . Moreover, when the end portion of the oil filter  16  is within the axial bore  30  of the body  20  of cover  14 , it extends beyond the housing  18 , within the cover  14 . This enables the oil filter  16  to have a greater axial length than the filter housing  18  within which it is accommodated. As a result, the dirt holding capacity and operational life of the oil filter  16  can be optimized, while the cover  14  remains within the spatial constraints that permit ready access to and removal of the cover  14  and oil filter  16  from the housing  18  of IDG  10  for routine maintenance purposes. 
     While the subject disclosure has been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.