Patent Publication Number: US-2010109214-A1

Title: Assembly For Transporting Pressurized Fluid and Method of Manufacture

Description:
TECHNICAL FIELD 
     The invention relates to an assembly for transporting pressurized fluid, such as in a vehicle transmission, and a method of manufacturing such an assembly. 
     BACKGROUND OF THE INVENTION 
     Pressurized fluid transport mechanisms are widely used in vehicle transmissions and engines to direct pressurized fluid as necessary for clutch engagement and other functions. Rigid metal tubes overmolded with rubber are known. The inner metal tube is necessary to provide the rigidity required to prevent blowout of the mechanism under the high fluid pressure forces. 
     SUMMARY OF THE INVENTION 
     An assembly for transporting pressurized fluid is provided that prevents expansion due to fluid pressure and the undesirable associated fluid pressure fluctuations associated with such expansion, while at the same time offering flexibility to compensate for tolerance variances in the components between which the fluid is transported, such as in a vehicle transmission or engine. Additionally, the assembly is easier to manufacture and assemble than known pressurized fluid transport devices. 
     Specifically, the assembly includes a flexible component, such as a molded rubber or other elastomer, that defines an interior passage through which the pressurized fluid flows. A sleeve surrounds at least a portion of the outer surface of the flexible component. The flexible component fits through an aperture in a support wall, such as a transmission casing, and has opposing first and second end portions configured to fit flush with a pressure source and a pressure destination when the component is through the aperture. The sleeve prevents expansion of the flexible component due to the pressurized fluid, such as expansion radially outward from the interior passage, but does not compromise the flexibility of the flexible component in a direction substantially parallel with the interior passage, thereby allowing compression between the two end portions as necessary to account for tolerance variances in the assembled pressure source and pressure destination. By preventing expansion, bursting of the respective seals formed between the end portions and the pressure source and pressure destination is avoided. 
     The sleeve may extend substantially from the first end portion to the second end portion through the aperture. Alternatively, first and second sleeves may be used to surround only the portions of the outer surface of the flexible component between the pressure source and the support wall, and between the pressure destination and the support wall, respectively. In another embodiment, the sleeve may be a spring, such as a wound wire that is compressible in the direction of the interior passage. 
     The flexible component may have multiple interior passages and conduit portions that are connected to one another via a flange molded from the same material and preferable unitary with the conduit portions. The sleeve as well may be a unitary sleeve configured to surround the outer surfaces of multiple conduit portions of a flexible component. 
     An optimal method of manufacturing a pressurized fluid transfer assembly includes extending a core pin into a die cavity for a die assembly and then molding the flexible component around the core pin in the die cavity without inserting any separate components in the die cavity so that the molded flexible component is of a single molded material and forms an internal passage around the core pin. That is, there is no rigid support molded within the flexible component, so a step of placing such a rigid component is avoided. This is beneficial, because time delay and more difficult temperature control of the die associated with repeated opening and closing of the die to insert such a rigid component is avoided. When the core pin is withdrawn and the molded flexible component is ejected from the die cavity, a sleeve can be placed around the flexible component to serve the purpose of preventing expansion due to fluid pressure, as discussed above. 
     The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic side view illustration of a first embodiment of a flexible molded component for transporting fluid; 
         FIG. 2  is a schematic side view illustration of a sleeve configured for use with the flexible component of  FIG. 1  as a pressurized fluid transport assembly; 
         FIG. 3  is a schematic end view illustration of the sleeve of  FIG. 2 ; 
         FIG. 4  is a schematic side view illustration of a second embodiment of a flexible molded component for transporting fluid; 
         FIG. 5A  is a schematic side view illustration of a sleeve configured for use with the flexible component of  FIG. 4  as a pressurized fluid transport assembly; 
         FIG. 5B  is a schematic side view illustration of another sleeve configured for use with the flexible component of  FIG. 4  as an alternative pressurized fluid transport assembly; 
         FIG. 6  is a schematic side view illustration of the pressurized fluid transport assembly utilizing the flexible molded component of  FIG. 1  and sleeves as shown in  FIGS. 2 and 3  to transport fluid from a transmission valve body to a clutch cavity within a transmission casing; 
         FIG. 7  is a schematic cross-sectional illustration of the pressurized fluid transport assembly taken at the lines  7 - 7  in  FIG. 6 ; 
         FIG. 8  is a schematic side view illustration of a third embodiment of a pressurized fluid transport assembly; 
         FIG. 9  is a schematic end view illustration of the pressurized fluid transport assembly of  FIG. 8 ; 
         FIG. 10  is a schematic side view illustration of a fourth embodiment of a pressurized fluid transport assembly; 
         FIG. 11  is a schematic end view illustration of the pressurized fluid transport assembly of  FIG. 10 ; 
         FIG. 12  is a schematic cross-sectional illustration of a die assembly for molding the flexible component of  FIG. 4 ; 
         FIG. 13  is a flow diagram illustrating a method of manufacturing pressurized fluid transport assemblies. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, wherein like reference numbers refer to like components,  FIG. 1  shows a flexible component  10  formed with an interior passage  12  passing completely through the component  10 . The flexible component  10  may be rubber or any other elastomer, and may be blow-molded according to the method of manufacture described herein. The flexible component  10  is a single, unitary component of a single material, such as an elastomer, and is not overmolded onto any support structure, such as prior art fluid transport mechanisms. This simplifies the manufacturing process, as described below with respect to  FIGS. 12 and 13 . 
     The flexible component  10  is formed with first and second recessed portions  14 ,  16  along an outer surface  18  thereof. The first and second recessed portions  14 ,  16  are adjacent respective tapered first and second end portions  20 ,  22 . Referring to  FIGS. 2 and 3 , a substantially rigid annular first sleeve  24  forms an opening  25  sized to fit snugly around the outer surface  18  in the recessed portion  14  of the flexible component  10 , as shown in  FIG. 6 . A substantially identical second sleeve  26  is sized to fit snugly around the outer surface  18  in the recessed portion  16 , also shown in  FIG. 6 . 
     The flexible component  10  with sleeves  24 ,  26  placed thereon forms an assembly  28  configured to transport pressurized fluid from a passage  30  in a pressure source  32 , such as a transmission valve body operatively connected with a transmission pump (not shown), to a pressure destination  34 , such as a support member within the transmission having a fluid channel  36  operatively connected with a pressure cavity for a transmission clutch (not shown). The assembly  28  is configured to pass through an aperture  37  in a support wall  38 , such as an outer wall of a transmission casing. The end portions  20 ,  22  are flush fit against the pressure destination  34  and the pressure source  32  at the passage  30  and fluid channel  36 , respectively. The flexibility of the component  10  allows the component  10  to compress slightly as necessary to maintain adequate sealing at the passage  30  and channel  36  while accommodating for slight build tolerances or variances in the distance D between the pressure source  32  and the pressure destination  34 . Because the sleeves  24  and  26  surround only portions of the outer surface  18 , they do not interfere with compression of the component  10  in a direction parallel with the interior passage  12  (i.e., an axial direction), especially compression of the end portions  20 ,  22 . The sleeves  24 ,  26  do not extend into the opening  37 , although in other embodiments they may. The sleeves  24 ,  26  are of a substantially rigid material, such as steel, aluminum, or a relatively hard plastic, sufficiently strong to prevent radial expansion of the flexible component  10  when high pressure fluid flows through the interior passage  12 . Thus, the sleeves  24 ,  26  protect those portions of the flexible component  10  not radially bounded by the support wall  38  from expanding to “burst” the flush fit seal of the end portions  20 ,  22  when high pressure fluid flows through the interior passage  12 .  FIG. 7  shows the sleeve  26  around the flexible component  10  (in recess  16  of  FIG. 1 ). 
     Referring to  FIG. 4 , a second embodiment of a flexible component  110  is shown with an interior passage  112  and an outer surface  118 . The interior passage  112  runs completely thought the flexible component  110 , including through tapered end portions  120 ,  122 . Referring to  FIG. 5A , a second embodiment of a substantially rigid annular sleeve  124  forms an opening  125  sized to fit snugly around the outer surface  118  of the flexible component  110  between the two end portions  120 ,  122  to form a pressurized fluid transport assembly. The outer surface of the sleeve  124  may be sized to fit through an aperture in a support wall, such as aperture  37  in  FIG. 6 , with the end portions  120 ,  122  sealing to the pressure source  32  and the pressure destination  134 , in lieu of the assembly  28 . The assembly formed by the flexible component  110  of  FIG. 4  and the sleeve  124  of  FIG. 5A  may be able to accommodate even more tolerance stackup between the pressure source  32  and pressure destination  34  (i.e., even more variance in the distance D), as the midportion of the assembled component  110  and sleeve  124  need not be aligned axially with the support wall  38  as must midportion  40  of the assembly  28 , because the midportion of component  110  is covered by sleeve  124 , protecting it from radial expansion, unlike midportion  40  of component  10 , which must be aligned with support wall  38  for protection from radial expansion. Referring to  FIG. 5B , another embodiment of a sleeve  124 B is shown which may be used in lieu of sleeve  124 A. Sleeve  124 B is a wound spring wire configured to fit around the outer surface  118  of the flexible component  110  of  FIG. 4  between the two end portions  120 ,  122  to prevent radial expansion but allow axial compressibility of the flexible component. 
     Referring to  FIG. 8 , a third embodiment of a pressurized fluid transport assembly  228  is shown. In this embodiment, the flexible component  210  has four conduit portions  211 ,  213 ,  215 ,  217  connected with one another via a flange portion  244 . The conduit portions  211 ,  213 ,  215  and  217  and the flange portion  244  are a unitary flexible material that may be blow-molded and manufactured according to the process described in  FIG. 14 . There are no separate components to which the flexible component  210  is overmolded or otherwise integrated with. Each of the conduit portions  211 ,  213 ,  215  and  217  form a separate interior passage  212 ,  246 ,  248  and  250  for transporting pressurized fluid, which may be at different pressures. 
     Each conduit portion  211 ,  213 ,  215  and  217  is formed with two recessed portions, with only recessed portions  214 ,  216  of conduit portion  211  and recessed portions  252  and  254  of conduit portion  213  being visible in  FIG. 8 , but with like recessed portions formed in conduit portions  215  and  217 . A respective annular sleeve is placed about each recessed portion, with annular sleeves  224 ,  226 ,  260  and  262  being visible in  FIG. 8 , and additional annular sleeves  264  and  266  being visible in  FIG. 9 . 
     The assembly  228  is designed for transporting fluid through four openings in a support wall from four separate openings in a pressure source such as pressure source  32  to four separate openings in a pressure destination such as pressure destination  34 , with the end portions of each respective conduit portion  211 ,  213 ,  215 ,  217  flush fit against the openings due to the ability to compress axially. The midportion of each conduit portion of the flexible component  228  would be protected from radial expansion by the support wall, as is the midportion of the assembly  28  in  FIG. 6 . 
     Referring to  FIGS. 10 and 11 , another embodiment of a pressurized fluid transport assembly  328  is shown. In this embodiment, four separate flexible components  310 A,  310 B,  310 C and  310 D are shown. Each of the flexible components  310 A- 310 D is substantially identical to the flexible component  10  shown and described in  FIG. 1 . First and second sleeves  324  and  326  are fit within respective recessed portions of each of the flexible components, as shown in  FIGS. 10 and 11 . Each of the sleeves  324 ,  326  has four annular portions with a flange  370  connecting the annular portions such that the respective sleeve  324 ,  326  is a unitary component. The annular portions  326 A,  326 B,  326 C and  326 D of sleeve  326  are shown in phantom, hidden by the end portions of flexible components  310 A,  310 B,  310 C and  310 D, with the flange  370  connecting each of the annular portions  326 A- 326 D. 
     Still other embodiments of fluid transport assemblies will be readily known to those skilled in the art based on the disclosure herein. For example, The flange portion  244  of  FIGS. 8 and 9  may be formed at other locations along the conduit portions  310 A- 310 D, or may be formed on conduit portions similar to the flexible component  110  of  FIG. 4 . Additionally, the integral sleeves each with four annular portions and a flange, shown in  FIGS. 10 and 11 , could be replaced by a single similar elongated sleeve in order to join four separate flexible components configured like flexible component  110  of  FIG. 4 . Also, the flange  370  of sleeve  326  (and like flange  372  of sleeve  324 ) may be of many different variations, each sufficient to connect the four annular portions  326 A- 326 D (or annular portions (unnumbered) of sleeve  324 ) to form a unitary sleeve  326  (or  324 ). 
     Referring to  FIG. 12 , a die assembly  410  is shown. The die assembly  410  is used to mold the flexible component  110  of  FIG. 4  according to the method of  FIG. 13 . The method of  FIG. 13  may be applied to the other flexible components shown and described herein as well, by providing a differently shaped die cavity than die cavity  412  of  FIG. 12 . The die assembly includes die portions  413  and  415  that together form the cavity  412 . Passages  414 A and  414 B lead from material reservoirs  416 A and  416 B, from which the material used to form the flexible component  110  is injected into the cavity  412 . A core pin  418  is shown positioned above the cavity  412 . According to the method  500  of  FIG. 13 , in step  502 , the core pin  418  is extended into the die cavity  412  to the position shown in phantom as  418 A (i.e., extending across the entire cavity  412 ). In step  504 , the flexible component  110  is then molded around the core pin  418  in the die cavity  412  by injecting material from the reservoirs  416 A,  416 B. The molded component  110  may then be withdrawn from the die assembly  410  in step  506 . Step  506  may include withdrawing the core pin  418  from the cavity  412  and opening the die assembly  410 . With the flexible component  110  now completed, the sleeve  124 A (or alternatively, sleeve  124 B) may be placed around the outer surface  118  of flexible component  110  in step  108  to complete the pressurized fluid transfer assembly, which is then ready for use to transport fluid between the pressure source  32  and pressure destination  34  through the support wall  38  of  FIG. 6 . 
     While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.