Abstract:
An example accumulator reservoir includes a housing. The housing contains a system fluid chamber, a working fluid chamber, and a residual chamber. Vent paths are configured to vent fluid from the residual chamber. Each of the vent paths extends nonlinearly between a first opening and a second opening.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This disclosure claims priority to U.S. Provisional Application No. 61/434,930, which was filed on 21 Jan. 2011 and is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    This disclosure relates generally to venting and, more particularly, to venting an accumulator reservoir. 
         [0003]    Accumulator reservoirs are well known. Many closed loop cooling systems include a pump that circulates fluid. The accumulator reservoir is used to maintain fluid pressure on the inlet side of the circulation pump. There are various types of accumulator reservoirs, such as bootstrap, bellows, gas charged, etc. 
         [0004]    In a bootstrap accumulator reservoir, a main piston moves within a housing to accommodate changes in the volume of a system fluid within the housing. A pump within the system discharges a working fluid that is used to pressurize an actuator cylinder of the bootstrap accumulator reservoir. The actuator cylinder opposes movement of the main piston. 
         [0005]    Venting areas of the accumulator is often necessary. Venting allows air or fluid to move in and out of areas of the accumulator as the main piston moves within the housing. Venting prevents the compressible air from affecting pressure balance on the main piston, and facilitates smooth movement of the main piston within the housing. Contaminants can undesirably enter the accumulator reservoir through such a vent. Contaminants can negatively affect the performance of seals and smooth action of the accumulator reservoir. 
       SUMMARY 
       [0006]    An example accumulator reservoir includes a housing. The housing contains a system fluid chamber, a working fluid chamber, and a residual chamber. Vent paths are configured to vent fluid from the residual chamber. Each of the vent paths extends nonlinearly between a first opening and a second opening. The fluid is air in one example. 
         [0007]    Another example accumulator reservoir includes a housing and a main piston received within the housing. An actuator chamber is on a first side of the main piston. A residual chamber is also on the first side of the main piston. An accumulator reservoir chamber is on an opposing, second side of the main piston. Crooked vent paths are configured to vent fluid from the residual chamber. The fluid is air in one example. 
         [0008]    The example method of venting an accumulator reservoir to restrict ingress of contaminants includes communicating fluid between a chamber within the accumulator reservoir and an outside environment through a plurality of crooked vent paths. The chamber is separate from a system fluid chamber and a working fluid chamber. The fluid is air in one example. 
     
    
     
       DESCRIPTION OF THE FIGURES 
         [0009]    The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description. The figures that accompany the detailed description can be briefly described as follows: 
           [0010]      FIG. 1  shows a section view of an example boot strap accumulator reservoir. 
           [0011]      FIG. 2  shows a perspective view of a portion of an actuator cylinder base of the  FIG. 1  accumulator reservoir. 
           [0012]      FIG. 3  shows a perspective view of a portion of a reservoir housing of the  FIG. 1  accumulator reservoir. 
           [0013]      FIG. 4  shows a perspective view of portions of the accumulator reservoir, with items of  FIGS. 2 and 3  assembled together. 
           [0014]      FIG. 5  shows a close-up section view of a portion of the  FIG. 1  accumulator reservoir. 
           [0015]      FIG. 6  shows a perspective view of another example actuator cylinder base. 
           [0016]      FIG. 7  shows another perspective view of the  FIG. 6  actuator cylinder base. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Referring to  FIG. 1 , an example accumulator reservoir  10  includes an actuator cylinder base  12  and a main piston  14  received within a reservoir housing  16 . A first axial end of the housing  16  is sealed and secured directly to a base  18 . An opposing axial end of the housing  16  is covered by a cap  20 . The housing  16  extends along an axis A and is generally cylindrical. The accumulator reservoir  10  is a bootstrap accumulator reservoir in this example. 
         [0018]    The accumulator reservoir  10  includes a system fluid chamber  22  on one side of the main piston  14 . A working fluid chamber  24  and a residual chamber  26  are included on an opposing side of the main piston  14 . 
         [0019]    During operation, a system fluid may leak, expand, or contract, and require communication to and from the system fluid chamber  22 . A system fluid supply  28  provides the system fluid. Adding system fluid to the system fluid chamber  22  urges the main piston  14  upward in an axial direction D 1 . 
         [0020]    A working fluid also communicates to and from the working fluid chamber  24 . A working fluid supply  30 , such as a pump discharge, provides the working fluid. Adding working fluid to the working fluid chamber  24  urges the actuator cylinder  12  downward in an axial direction D 2 . As can be appreciated, urging the actuator cylinder  12  downward causes the actuator cylinder  12  to oppose the upward movement of the main piston  14 . The actuator cylinder  12  thus helps the main piston  14  maintain pressure on the system fluid. 
         [0021]    As the main piston  14  moves upward in the direction D 1 , the residual chamber  26  is compressed. As the main piston  14  moves downward in the direction D 2 , the residual chamber  26  is expanded. The example residual chamber  26  is annular and is typically filled with a compressible fluid, such as air during operation of the accumulator reservoir  10 . The residual chamber  26  is vented so that fluid can communicate to and from the residual chamber  26  as needed. Venting the residual chamber  26  ensures that any pressure exerted by the fluid in the residual chamber  26  does not substantially influence pressure balance, or controlled movement of the main piston  14  relative to the housing  16 . 
         [0022]    Referring now to  FIGS. 2-5  with continuing reference to  FIG. 1 , a plurality of vent paths  32  are used to communicate fluid to and from the residual chamber  26 . The example vent paths  32  are established by a collar  34  of the housing  16  and a radial flange  36  of the actuator cylinder  12 . In this example, the vent paths  32  are arranged in a circular array about the axis A. 
         [0023]    The example vent paths  32  extend from an arrangement of first openings  38  to an arrangement of second openings  40 . The first openings  38  interface directly with the residual chamber  26 . The second openings  40  interface directly with an environment surrounding the accumulator reservoir  10 . These path segments all interconnect with the annular path formed by the edge chamfer  44 . 
         [0024]    The example vent paths  32  include axially directed segments  42 , circumferentially directed segments  44 , and radially directed segments  46 . For a fluid to move between the residual chamber  26  and a surrounding environment, the air must move, at a minimum, through one of the axially directed segments  42 , one of the circumferentially directed segments  44 , and one of the radially directed segments  46 . This multitude of paths can and will operate in parallel and provide an interconnected network of vent flows, making the system resistant to blockage. 
         [0025]    The example vent paths  32  are thus nonlinear as fluid communicated along the vent paths  32  does not travel between the arrangement of first openings  38  and the arrangement of second openings  40  in a straight line. The vent paths  32  are considered crooked in some examples, and the fluid is considered to have a tortured flow path. A direction of flow F through some of the portions of the vent paths  32  is shown generally in  FIG. 4 . 
         [0026]    In this example, the vent paths  32  include six axially directed segments  42  that are evenly circumferentially distributed about the axis. Also, the example vent paths  32  include six radially directed segments  46  that are evenly circumferentially distributed about the axis. 
         [0027]    Although the example vent paths  32  are described as having portions defined by both the actuator cylinder  12  and the housing  16 , those having skill in the art and the benefit of this disclosure will understand that either the actuator cylinder  12  or the housing  16  alone may define the vent paths  32 . 
         [0028]    Also, other components may be used to establish the vent paths  32 . For example, in another accumulator reservoir, vent paths could be established by the cap  20  and the actuator cylinder  12 . In yet another example, vent paths could be established by the housing  16 , the actuator cylinder  12 , and the cap  20 .  FIGS. 6 and 7  show example vent paths  32   a  that are established between the cap  20  and a flange  36   a  of an actuator cylinder  12   a . Notably, the machined portions dedicated to establishing the vent paths  32   a  are exclusively in the actuator cylinder  12   a.    
         [0029]    Referring again to  FIGS. 1-5 , the example actuator cylinder  12  is a telescoping actuator cylinder that includes an inner sleeve  50 , a mid sleeve  52 , and an outer sleeve  54 . As can be appreciated, the inner sleeve  50  is received within the mid sleeve  52  and the outer sleeve  54  as the actuator cylinder  12  is compressed due to movement of the main piston in the direction D 1 . Seals may be used to seal interfaces between the sleeves  50 - 54 . The main piston  14  also uses seals  56  to seal interfaces between the main piston  14  and an inner wall of the housing  16 . 
         [0030]    The cap  20  is secured directly to the flange  36  and the collar  34  of the housing  16  with a plurality of bolts  58 . The cap  20  covers and seals the working fluid chamber  24 . 
         [0031]    Notably, the example actuator cylinder base  12  also includes a lip  60  extending downwardly from the radially extending flange  36 . The downwardly extending lip  60  extends in the direction D 2  past the second openings  40 . The lip  60  shields the openings  40  from directly jetted fluids or particulates of the surroundings. The cap  20  may establish the lip  60  in some examples, such as when the vent paths  32   a  are established between the cap  20  and the flange  36   a.    
         [0032]    Features of the disclosed example include venting an accumulator through crooked paths to discourage contaminants from entering the residual chamber. Another feature is the downwardly extending lip, which also discourages contaminants from entering the vent paths. Yet another feature is distributing the vents circumferentially. 
         [0033]    The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Thus, the scope of legal protection given to this disclosure can only be determined by studying the following claims.