Abstract:
A fill cap assembly for a transmission is provided. In one form, the fill cap assembly includes a first part and a second part, each defining a cavity therein. A flexible membrane is disposed between the first and second parts and separates the cavities of the first and second parts. The cavities are sealed from each other by the membrane. The cavity of the first part is configured to be in fluid communication with the inside of the transmission. When pressure rises in the transmission, the flexible membrane expands into the cavity of the second part. When pressure sinks in the transmission, the membrane collapses partially into the cavity of the first part, thus expanding out of and/or away from the cavity of the second part.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/845,033, filed on Jul. 11, 2013, which is herein incorporated by reference in its entirety. 
     
    
     FIELD 
       [0002]    The present disclosure relates to devices for venting automatic transmissions, and more specifically, to a vent cap or fill cap assembly for an automotive transmission that allows for pressure fluctuations in the transmission. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0004]    A transmission, particularly a hydraulically controlled planetary gear automatic transmission for a motor vehicle, operates at temperatures well above ambient, often at 130° C. (265° F.) or higher. Because the transmission may begin operation at ambient temperatures as low as −35° C. (−30° F.) or lower, the air within the transmission will undergo significant expansion. Conversely, when the transmission becomes inactive, the transmission&#39;s nominal temperature may drop relatively rapidly and the air within the transmission will contract. In order to accommodate these changes and to avoid pressurization or a partial vacuum within the transmission, a transmission is equipped with a breather system which allows exhaust and ingestion of air. 
         [0005]    The vent cap openings, however, may allow the intrusion of debris and liquid, such as water, into the transmission, which may be undesirable. Certain arrangements of transmission vent caps include a mesh positioned over the opening to prevent debris from entering the housing, but these meshes do not keep liquid from intruding into the transmission. Accordingly, there is a need for a cover that allows pressure fluctuations and heat to vent from the transmission, without allowing liquid or debris to enter into the transmission. 
       SUMMARY 
       [0006]    The present disclosure provides a fill cap, or vent cap, for a transmission assembly that prevents debris and moisture from entering the transmission, but also compensates for and allows for pressure fluctuations within the transmission. 
         [0007]    In one aspect, which may be combined with or separate from the other aspects described herein, a vent cap or fill cap assembly for a transmission is provided that includes a rigid base and a flexible membrane. The flexible membrane is sealed against the base such that no liquid or debris can enter or exit the base through or adjacent to the membrane. The base may have an inner cavity that is in fluid communication with the inside of a transmission assembly. If pressure rises within the transmission, the flexible membrane is configured to fluctuate and expand in an outward direction from the base; and if pressure sinks within the transmission, the flexible membrane is configured to compress or collapse toward the in base and into the cavity of the base. 
         [0008]    In another aspect, which may be combined with or separate from the other aspects described herein, the fill cap assembly includes rigid lower and upper parts, which may be shaped as half spheres, cylinders, boxes, or any other suitable shape. A flexible membrane is disposed between the lower part and the upper part. The lower and upper parts each define a cavity disposed on a side of the membrane. The upper and lower cavities are sealed from each other by the flexible membrane. The cavity of the lower part is in communication with the inside of the transmission. When pressure rises in the transmission, the flexible membrane expands into the cavity of the upper part. When pressure sinks in the transmission, the flexible membrane collapses partially into the cavity of the lower party, thus expanding away from the cavity of the upper part. 
         [0009]    In yet another aspect, which may be combined with or separate from the other aspects described herein, a fill cap assembly for a vehicular transmission is provided. The fill cap assembly includes a fill part forming a cavity therein, the fill part having a fill part edge. A channel portion forms a channel in the fill part. The channel is configured to fluidly connect the cavity of the fill part to an inner space within the vehicular transmission. A flexible membrane is disposed adjacent to the fill part edge. The flexible membrane is connected to the fill part edge to form a seal along the fill part edge. The flexible membrane is configured to expand when pressure rises within the cavity. 
         [0010]    In still another aspect, which may be combined with or separate from other aspects described herein, a fill cap assembly for a vehicular transmission is provided. The fill cap assembly includes a flexible membrane configured to contract and expand, a structure connected to the flexible membrane, and a channel portion. The structure and the flexible membrane cooperate to form a cavity therebetween. The channel portion forms a channel therein. The channel is configured to fluidly connect the cavity to an inner space within the vehicular transmission. The cavity is fluidly sealed except for the channel that communicates with the cavity. 
         [0011]    In still another aspect, which may be combined with or separate from the other aspects described herein, a fill cap assembly for a vehicular transmission is provided. The fill cap assembly includes a first sphere half forming a first cavity therein. The first sphere half defines a round first edge. A projection extends from a side wall of the first sphere half, and the projection defines a channel therein. The channel is in fluid communication with the first cavity, and the channel being configured to fluidly connect the first cavity to an inner space within the vehicular transmission. A second sphere half forms a second cavity therein, and the second sphere half defines a round second edge. The round second edge is connected to the round first edge. An elastomeric membrane is disposed between the first and second sphere halves adjacent to the first and second round edges. The elastomeric membrane forms a seal between the first and second cavities, and the first and second cavities are not in fluid communication with each other. The elastomeric membrane is configured to expand when pressure rises within the first cavity. 
         [0012]    Further aspects, advantages and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0013]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0014]      FIG. 1A  is a perspective view of a portion of a motor vehicle including a transmission and a fill cap assembly, according to the principles of the present disclosure; 
           [0015]      FIG. 1B  is a perspective view of the fill cap assembly of  FIG. 1A  attached to a vehicle structure, in accordance with the principles of the present disclosure; 
           [0016]      FIG. 1C  is a partially exploded perspective view of the fill cap assembly of  FIGS. 1A-1B , according to the principles of the present disclosure; 
           [0017]      FIG. 1D  is a side schematic cross-sectional view of the fill cap assembly of  FIGS. 1A-1C , showing the fill cap assembly in an unexpanded configuration, in accordance with the principles of the present disclosure; 
           [0018]      FIG. 1E  is a side schematic cross-sectional view of the fill cap assembly of  FIGS. 1A-1D , showing the fill cap assembly in an expanded configuration, according to the principles of the present disclosure; 
           [0019]      FIG. 1F  is a side schematic cross-sectional view of the fill cap assembly of  FIGS. 1A-1E , showing the fill cap assembly in a collapsed configuration, in accordance with the principles of the present disclosure; and 
           [0020]      FIG. 2  is a side schematic cross-sectional view of another fill cap assembly in accordance with the principles of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0022]    With reference to the figures, a transmission assembly is illustrated and generally designated at  10 . The transmission assembly  10  is installed within a motor vehicle. The transmission assembly  10  includes an automotive transmission  14  and a fill cap assembly  16  (or vent cap assembly). 
         [0023]    The transmission assembly  10  is attached to vehicle structure  12 . For example, the transmission  14  is bolted to the vehicle structure  12 , and the fill cap assembly  16  is also attached by bolts  17  to a vehicle shock tower  18 , which is also attached to vehicle structure  12 . 
         [0024]    The fill cap assembly  16  has a protrusion  20  extending from a lower part  22  of the fill cap assembly  16 . The protrusion  20  is connected to a hose  24 . The hose  24  extends from the fill cap assembly  16  to the transmission  14 . Accordingly, the hose  24  fluidly connects a chamber or cavity inside the fill cap assembly  16  with the inside of the transmission  14 , which will be described in further detail below. The hose  24  may be connected to the transmission  14  by another structure, such as a vent cap attachment  26  that has an opening fluidly connecting the hose  24  with the inside of the case of the transmission  14 . 
         [0025]    Accordingly, in the illustrated example, the fill cap assembly  16  is rigidly attached to the shock tower  18  instead of to the transmission  14 , but it should be understood that the fill cap assembly  16  alternatively could be attached to any other suitable structure in the vehicle, such as to the top side of the case of the transmission  14  itself. 
         [0026]    The fill cap assembly  16 , along with a hose  24  attached thereto, allows the transmission  14  to “breathe,” for example, to allow air pressure to move into and out of the case of the transmission  14  through the hose  24 , and specifically, through the hose  24  attached to the chamber of the lower part  22  of the fill cap assembly  16 . In other words, the fill cap assembly  16  allows for pressure fluctuation due to temperature variation but prevents debris and moisture from entering into the transmission  14 . 
         [0027]    In the illustrated example, the fill cap assembly  16  includes a lower sphere half part  22  and an upper sphere half part  28 . A pressure blow-off valve  30  is disposed at the top of the upper part  28 . A weld joint  32 , or other joint, joins the upper part  28  to the lower part  22 , thus creating a rigid base made of the upper and lower parts  28 ,  22 . 
         [0028]    Referring now to  FIG. 1C , the fill cap assembly  16  is shown in a partially exploded view, showing the inner contents of the fill cap assembly  16 . Each of the lower and upper parts  22 ,  28  is hollow and has an inner cavity; thus, the lower half-spherical part  22  defines a lower inner cavity  34  and the upper half-spherical part defines an upper inner cavity  36 . The upper inner cavity  36  communicates with the blow-off valve  30 , which may be a one-way valve. The lower inner cavity  34  is in communication with a channel  38  in the protrusion  20 . Therefore, when the hose  24  is connected to the protrusion  20 , the hose  24  fluidly connects the lower inner cavity  34  with the inside of the transmission  14 . 
         [0029]    A flexible membrane  40  is disposed between the lower and upper cavities  34 ,  36  of the lower and upper parts  22 ,  28 . The flexible membrane  40  may be fixed into place between the lower and upper parts  22 ,  28  when the parts  22 ,  28  are connected together by the weld joint  32  or in any other suitable manner. In the illustrated example, the flexible membrane  40  rests on a lip  42  of the lower part  22 , which follows the circumference of the edge of the lower part  22 . The flexible membrane  40  is clamped into place between the lower and upper parts  22 ,  28  when the parts  22 ,  28  are joined by the weld joint  32  or another joint. The flexible membrane  40  separates the upper cavity  36  from the lower cavity  34  such that the cavities  36 ,  34  are not in fluid communication with each other. In the illustrated example, the flexible membrane  40  is a flat disc when in the unexpanded configuration. 
         [0030]    The flexible membrane  40  may be formed of any suitable flexible material. In one example, the flexible membrane  40  is formed of an elastomeric material, such as synthetic or natural rubber. The upper and lower parts  28 ,  22  may also be formed of any suitable material, such as rubber or plastic, or a composite plastic. A composite plastic such as a glass-filled plastic is a suitable material that provides the fill cap assembly  16  with a desired light weight. Should the lower and upper parts  22 ,  28  be formed of a composite plastic, they could be sonic welded together to create the weld joint  32  and to clamp the flexible membrane  40  between the upper and lower parts  28 ,  22 . 
         [0031]    Referring now to  FIG. 1D , the fill cap assembly  16  is illustrated in a schematic cross-sectional view, showing the membrane  40  disposed between the upper and lower sphere halves  28 ,  22  in an unexpanded position or configuration. In this position, there has been little or no pressure fluctuation in the transmission  14  from the pressure at which the fill cap assembly  16  was installed or the rest pressure of the transmission  14 . (It should be understood that the unexpanded configuration of the flexible membrane  40  could be configured to be present at any desired pressure of the transmission  14 ). Accordingly, the flexible membrane  40  extends approximately flat and horizontally through the sphere halves  22 ,  28 , resembling a flat, circular disc in the illustrated example. 
         [0032]    Referring to  FIG. 1E , a pressurized lower cavity  34  is illustrated. In  FIG. 1E , the pressure in the transmission  14  has risen, typically due to a rising temperature. Therefore, the air in the transmission  14  has expanded and the greater air volume escapes the transmission  14  through the hose  24  and into the cavity  34  of the lower part  22 . When the air volume in the lower cavity  34  expands, the flexible membrane  40  expands, or stretches, in an upward direction into the cavity  36  of the upper part  28 , as illustrated by arrow  44 . In other words, when the pressure builds in the cavity  34  of the lower part  22 , the flexible membrane  40  expands in the upward direction  44 . 
         [0033]    The lower cavity  34  remains isolated from the upper cavity  36 , such that no debris or moisture enters the lower cavity  34  from the upper cavity  36 . When the flexible membrane  40  expands into the upper cavity  36  as shown in  FIG. 1E , the air pressure in the upper cavity  36  increases, and if the air pressure exceeds a predetermined level, air pressure escapes through the blow-off valve  30 , as illustrated schematically by arrow  46 . For example, as the flexible membrane  40  compresses the air in the upper cavity  36  of the upper part  28 , air is forced out of the upper cavity  36  through the blow-off valve  30 . 
         [0034]    The upper part  28  protects the flexible membrane  40  from damage, but in some variations, the upper part  28  could be eliminated and the flexible membrane  40  could merely be sealed to the lower part  22 . 
         [0035]    Referring now to  FIG. 1F , the flexible membrane  40  is illustrated as being collapsed in a downward direction, as indicated by arrow  48 , and partially into the lower cavity  34 . The flexible membrane  40  collapses into the lower cavity  34  as illustrated when there is a predetermined level of a negative pressure within the transmission  14 , such as when the transmission is cold or cools down. When the flexible membrane  40  collapses as illustrated in  FIG. 1F , the blow-off valve  30  is sucked closed by the negative pressure, in the direction  50  as illustrated. 
         [0036]    Referring now to  FIG. 2 , another variation of a fill cap assembly is illustrated and generally designated at  16 ′. Like the fill cap assembly  16  described above, the fill cap assembly  16 ′ in  FIG. 2  includes upper and lower sphere halves or parts  128 ,  122  welded together at weld joint  132 . A flexible membrane  140  is disposed between the upper and lower parts  128 ,  122  and separates upper and lower cavities  136 ,  134 , as described above, and the upper cavity  136  communicates with a blow-off valve  130 . The flexible membrane  140  is illustrated in an unexpanded configuration, as shown in  FIG. 1D . 
         [0037]    In the example in  FIG. 2 , the fill cap assembly  16 ′ includes a protrusion  152  extending from the lower part  122  that may be directly attached to a transmission, such as transmission  14 . For example, in one variation, the protrusion  152  bears threads  154  that may be used to screw the protrusion  152 , and thus the fill cap assembly  16 ′, to the transmission  14 . Once the fill cap assembly  16 ′ is screwed into the transmission  14 , an O-ring  156  assists in sealing the fill cap assembly  16 ′ against the case of the transmission  14  to avoid leaks. A channel  158  through the protrusion  152  fluidly connects the lower cavity  134  to the inside of the case of the transmission  14 . Except for the differences described in this paragraph, the fill cap assembly  16 ′ may operate the same as the fill cap assembly  16  described above, or with any other variation described herein. 
         [0038]    For example, the flexible membrane  40 ,  140  need not be a flat disc as illustrated. In one alternative embodiment, the flexible membrane  40 ,  140  could comprise bellows disposed between the upper and lower parts  28 ,  128 ,  22 ,  122 , or the bellows could be located at the top of the lower part  22 ,  122  if the upper part  28 ,  128  is eliminated. In another variation, the lower and upper parts  22 ,  122 ,  28 ,  128  could have a shape other than a sphere shape; for example, the lower and upper parts  22 ,  122 ,  28 ,  128  could have a cylindrical, square, rectangular, or any other desired shape. The variation in shape of the lower and upper parts  22 ,  122 ,  28 ,  128  could also use the bellows variation of the flexible membrane  40 ,  140 . 
         [0039]    Thus, the present disclosure provides a sealed fill cap assembly  16 ,  16 ′ that allows for pressure fluctuation in the transmission  14 , but prevents debris and moisture from entering into the case or other inside part of the transmission  14 . The flexible membrane  40 ,  140  compensates for pressure fluctuations by expanding in an upward or downward direction. 
         [0040]    The description of the invention, and certain embodiments of it, is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.