Abstract:
A marine steering fluid system sight gauge comprises a hollow body having an annular first end, a second end, and a substantially transparent intermediate portion. The annular first end is externally threaded and screws into and sealingly engages against a threaded aperture of a marine steering fluid system. The second end is internally threaded and sealingly receives the threaded cylindrical plug of a marine steering fluid system cap. The hydraulic fluid level is periodically inspected by viewing the level of fluid in the transparent intermediate portion of the sight gauge.

Description:
[0001]    The present application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application Ser. No. 61/346,176 filed on May 19, 2010. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to an apparatus and method for retrofitting marine hydraulic steering systems to enable visual inspection and determination of the presence of a safe level of hydraulic fluid in the hydraulic steering system, and more specifically, relates to a sight gauge kit which can be attached to a steering fluid reservoir to inspect the level of hydraulic fluid. 
       BACKGROUND OF THE INVENTION 
       [0003]    Marine hydraulic steering systems are typically used in both large ships as well as power boats. The hydraulic systems are used to position the rudder to change direction of travel of the craft. However, a frequent problem, particularly with older boats, is the leakage of hydraulic fluid around seals, and losses of fluid through other means. Insufficient hydraulic fluid in the steering system will lead to the loss of steering control, rendering the boat dangerously unnavigable. 
         [0004]    In typical power boat marine hydraulic steering systems the only way to detect low levels of hydraulic fluid is to unscrew the cap of the system and visually inspect the level of fluid. This is typically only possible when the boat is at rest, for example at a dock or mooring. It is not possible to continuously monitor hydraulic fluid levels while the boat is underway because opening the cap will cause spillage and loss of the hydraulic fluid. Accordingly, a boater may suddenly reach an insufficient level of hydraulic fluid while underway. This is potentially very dangerous, as the boater may lose control of the boat at when the boat is travelling at a high speed or while it is in a close passage with another boat. 
         [0005]    What is desired, therefore, is an apparatus and method that allows a boater to easily retrofit existing power boat marine hydraulic systems to visually inspect and determine of the presence of a safe level of hydraulic fluid in the hydraulic steering system 
       SUMMARY OF THE INVENTION 
       [0006]    The invention is directed to a sight gauge for use in determining if a leak is present in a hydraulic fluid system. The design allows for a user to easily install a sight gauge into the inlet port of a hydraulic fluid system to determine if the hydraulic fluid level is low, or if a leak is present in the hydraulic fluid system. 
         [0007]    It is an object of the present invention is to provide a sight gauge which does not require a hydraulic fluid system to be modified in order to use the gauge. 
         [0008]    These and other objects of the present invention are achieved by provision of a sight gauge system having an annular first end, an annular second end, and an intermediate portion extending between the first end and the second end. The body is cylindrical in shape and is composed of a substantially transparent plastic material; where the body is less than 3 inches in height and has a wall with a minimum thickness of ⅛ inch. A reservoir inside the body extends from the first end through the body to the second end. The first end has outer threads formed on the outer surface of the annular first end; the first end having an opening connecting with the reservoir and having a smaller diameter than the intermediate portion and the second end. An O-ring seal is fitted on to the annular first end. The second end has inner threads formed on the inner surface of the annular second end and a second opening in the second end connecting with the reservoir; the second opening being larger than the first opening. A screw cap having a threaded cylindrical plug, and a star-shaped knob containing finger grippable protrusions. The threaded cylindrical plug is sized to be threaded into the annular second end. An O-ring seal is fitted into the annular second end. In some embodiments the transparent body is printed with a level indicator. In some of these embodiments the transparent body is covered with a transparent adhesive with a printed level indicator. 
         [0009]    In accordance with another embodiment of the present invention there is a method of determining the presence of a leak in a hydraulic fluid system. The method comprises the steps of removing a cap from an opening in the hydraulic fluid reservoir; inserting the sight gauge into the opening of the hydraulic fluid reservoir; removing the cap from the sight gauge. Pouring liquid into the sight gauge; replacing the cap on the sight gauge; and continuously checking the fluid level of the sight gauge to determine if the fluid level in the sight gauge has dropped. 
         [0010]    The invention and its particular features and advantage will become more apparent from the following detailed description considered with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a top and front perspective view of a sight gauge according to the present invention. 
           [0012]      FIG. 2  is an exploded top and front perspective view of the sight gauge of  FIG. 1 . 
           [0013]      FIG. 3  is cross-sectional view of the line  3 - 3  of the sight gauge of  FIG. 1   a.    
           [0014]      FIG. 4  is a perspective view of the sight gauge of  FIG. 1  installed for use in a marine hydraulic steering fluid system of a power boat. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    The system and method of detecting a safe level of hydraulic fluid generally includes a portable sight gauge. 
         [0016]    As best seen in  FIGS. 1 and 2 , the sight gauge  100  may contain a body  105  and a screw-on cap  110 . The body is preferably made from a transparent or substantially transparent material such that the user can see a level of fluid inside of the body. The body may be made from glass, plastic, or any other known material for producing a transparent or substantially transparent device. The body may be colorless, or the body may be made from a colored material to add aesthetics and contrast to the sight gauge. 
         [0017]    Body  105  has an internal reservoir  120  that runs the length of, or substantially the length of the entire body. Internal reservoir  120  is designed to hold any liquid poured into the sight gauge  100 . Internal reservoir  120  may be of a predetermined volume such that the user of sight gauge  100  is aware of approximately how much hydraulic fluid can be held inside of internal reservoir  120 . Internal reservoir  120  can be of differing volume levels depending of the specific application of the sight gauge  100 . Internal reservoir  120  has two defined openings, as best seen in  FIGS. 2 and 3 . Body  105  has an upper fluid inlet port  215  which contains inner threading  130  inside of the inlet port and on the inner surface of the reservoir  120 . Cap  110  has cap threads  240  defined to be screwed into upper threads  130 . Cap threads  240  may further have a seal, which is an O-Ring or gasket  235  placed over cap threads  240  to provide a better seal between cap  110  and body  105 . It should be noted that while cap  110  and body  105  define threading to attach cap  110  to body  105 , cap  110  and body  105  may be attached by any known method including an interference fit. 
         [0018]    Body  105  has a lower fluid outlet port  230  and lower threading  115 . Lower threading  115  is defined on the outer surface of body  105 . Lower fluid outlet port  230  is preferably smaller than upper fluid inlet port  215  to allow for the liquid poured into the body to accumulate in internal reservoir  120 . However, it should be noted, that lower fluid outlet port  230  may be of any size including being equal to or greater in size than upper fluid inlet port  215 . Lower threads  115  are sized to be screwed into any reservoir of standard size. However, body  105  need not contain lower threads  115  and may use an interference fit, or any other type of known connection, to be inserted into a hydraulic fluid reservoir. Lower threads  115  further contains a second lower seal, such as an O-ring or gasket  220  to provide a greater seal between sight gauge  100  and the reservoir sight gauge  100  is attached to. 
         [0019]    Cap  110  is preferably sized such that the diameter of cap  110  is similar to the diameter of body  105  to provide a sleek look, and to limit the bulk and size of sight gauge  100 . However, cap  110  may be of any size including a diameter smaller or larger than the diameter of body  105 . Cap  110  is further shaped with finger-grippable protrusions to aid in the placement and removal of cap  110  from body  105 . In a preferred embodiment, cap  110  is star-shaped with 9 protrusions; however, cap  110  may be of any shape including any number of finger protrusions. 
         [0020]    Body  105  may contain printing or writing on the exterior surface of the body. The printing may be equally spaced lines to provide a level indicator for the user of the sight gauge  100 . A logo may also be printed on the body for advertisement purposes. Body  105  may also have a transparent adhesive tape (not shown) overlaid on body  105 . The adhesive tape may be transparent or substantially transparent and be of any color including colorless. The transparent adhesive may also be printed with a level indicator or a logo. 
         [0021]    As best seen in  FIG. 2 , an exploded view of sight gauge  100  is shown. To construct the sight gauge, the user places upper gasket  130  over cap threads  240 . The user then screws cap  110  into body  105 . Finally, the user places lower gasket  220  over lower threads  115 . 
         [0022]    As best seen in  FIG. 3 , a sliced view of sight gauge  100  is shown. Sight gauge  100  defines a thickness  310  between the outer surface and the inner surface of body  105 . Thickness  310  is preferably ⅛ inch thick, however, thickness  310  can be of any size greater than about 1/16 inch in thickness. The body  105  of sight gauge  100  is preferably about 1 inch″ in height, however, sight gauge may have a total height of up to about 3 inches. 
         [0023]    As best seen in  FIG. 4 , sight gauge  100  is attached to the hydraulic steering fluid reservoir  410  of boat  400 . The hydraulic steering fluid is used to control the steering of boat  400  through steering wheel  405 . The driver of the boat (not shown) sits or stands behind wheel  405 , with easy access to sight gauge  100 . In the figure shown, the hydraulic steering fluid reservoir is located behind wheel  405  of boat  400 ; however, the fluid reservoir may be in any location as designed by the boat designers. Sight gauge  100  is designed to be used to use in any hydraulic fluid reservoir, and be used at any angle designed by the boat designer. 
         [0024]    The method of use of the sight gauge of the invention is as follows. The user removes the hydraulic fluid cap of the hydraulic fluid system they intend to check the level of. The user removes the cap  110 , and screws the sight gauge  100  into the hydraulic fluid inlet port, making sure a tight seal is created. The user adds hydraulic fluid through the upper fluid inlet port  215  as needed until the sight gauge is full or substantially full, and does not quickly drain into the hydraulic fluid system. The user then screws the screw cap back onto the sight gauge. If any leak is present in the hydraulic fluid system, the level of fluid in the sight gauge  100  will decrease slowly or rapidly depending on the size of the leak. The user is free to remove cap  110  and add more hydraulic fluid to determine the extent of the leak. It should be noted, that the steps in the above method may be changed, for example, the user may attach sight gauge  100  to the hydraulic fluid reservoir before removing cap  110  from sight gauge  100 . 
         [0025]    This system and method has the advantage in that the existing hydraulic system does not need to be modified to determine if a leak exits. The user can temporarily install the sight gauge into a hydraulic fluid inlet port, add hydraulic fluid, and determine if a leak exists by checking if the level of fluid in the sight gauge decreases. The process is simple to use, and inexpensive to produce. Furthermore, the amount of time needed to determine if a leak exists is greatly reduced as the portable sight gauge can quickly determine if a leak exists. 
         [0026]    It would be appreciated by those skilled in the art that various changes and modifications can be made to the illustrated embodiment without departing from the spirit of the present invention. All such modifications and changes are intended to be covered hereby.