Abstract:
The present invention is directed to a pump arrangement for use in a gear box housing. The interior surface of the gear box housing has a collection wall arranged in the interior surface of the housing. A shaft is rotatably disposed through the gear box housing and has a longitudinal bore extending through the shaft that provides a lubrication delivery arrangement for distributing lubricant through the gear box housing. A pump housing circumscribes the shaft and has a discharge cavity connected to the longitudinal bore. Additionally, the pump housing has an inlet port for receiving lubrication from the collection wall. Contained within the pump housing is a pump member that has an impeller face and helical threaded surface that pressurizes and introduces the lubricant into the lubricant delivery arrangement.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/560,095, filed Apr. 7, 2004. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to a gear box pump for collecting and pressurizing lubricating fluid for delivery to specific locations within the gear box housing.  
       BACKGROUND OF THE INVENTION  
       [0003]     Gear boxes such as transfer cases will often require a system for the delivery of lubrication to various components within the gear box housing. For example, in a transfer case the bearings that rotatably support the various shafts within the transfer case housing need a steady supply of lubrication in order to prevent heat damage. Additionally, other components such as chains, gear sets and other torque transfer elements also need a steady source of lubrication. Typically the system for delivery of lubricant involves using a lubrication pump to pressurize and force the lubricant through a delivery arrangement to specific locations within the gear box housing. In vehicle transfer cases oftentimes the input shaft will have a longitudinally extending bore with various radial outputs for delivering lubricant from the longitudinal bore to a specific location within the transfer case housing. A pump is used to pressurize the lubricant and deliver it through the longitudinal bore that extends through the shaft. The pump is typically a gerotor type pump that is classified as a fixed displacement pump. A disadvantage of using a gerotor pump is that there can be a relatively high power loss associated with this type of pump. In some applications this high power loss is unacceptable. The objective of the present invention is to provide a lubrication pump that will deliver lubricating oil with a reduced power loss as compared to conventional style pumps.  
       SUMMARY OF THE INVENTION  
       [0004]     The present invention is directed to a pump arrangement for use in a gear box housing. A shaft is rotatably disposed through the gear box housing. The shaft has a longitudinal bore extending through the shaft which provides a lubrication delivery arrangement that distributes lubricant through the gear box housing. The interior surface of the gear box housing has a collection wall or lubrication furrow. A pump housing circumscribes the shaft and has a discharge cavity connected to the longitudinal bore. Additionally, the pump housing has an inlet port for receiving lubrication from the collection wall. Contained within the pump housing is a rotational pump member that circumscribes, is connected to and rotates with the shaft. The exterior surface of the pump member has an impeller face that is adjacent a helically extending pumping surface. The impeller face is arranged to receive lubrication from the inlet port and move the lubricant to the helically disposed pumping surface. As the pump member rotates with the shaft, lubrication moves along the helical grooves or threads on the exterior surface of the pump member. The lubricant gains pressure as it moves along the exterior surface and when the lubricant reaches the discharge cavity it is pressurized. In an alternate embodiment the helically extending pumping surface is disposed on an interior surface of the pump housing as opposed to being formed on the surface of the rotational pump member.  
         [0005]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0007]      FIG. 1  is an exploded side partial cross-section of  FIG. 2 ;  
         [0008]      FIG. 2  is a cross-sectional side view taken along section line  2 - 2 ;  
         [0009]      FIG. 3  is an end view of the pump housing where all of the other components will be assembled;  
         [0010]      FIG. 4  is an end view of the pump member;  
         [0011]      FIG. 5  is an end view of the collector;  
         [0012]      FIG. 6  is a cross-sectional plan side view of the pump connected to a shaft inside of a transfer case housing;  
         [0013]      FIG. 7  is a cross sectional view of the pump positioned in the transfer case housing; and  
         [0014]      FIG. 8  is a cross-sectional side plan view of a pump arrangement incorporating an alternate embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0016]      FIGS. 1-2  show side views of a pump arrangement  10  as it looks without being assembled in a gear box. As shown, the pump arrangement  10  has three main components consisting of a pump housing  12 , a collector  14  and a rotational or pump member  16 .  FIGS. 3-5  show plan end views of the pump housing  12  (shown in  FIG. 3 ), the pump member  16  (shown in  FIG. 4 ) and the collector  14  (shown in  FIG. 5 ).  
         [0017]     The collector  14  has an aperture  15  which is used to fix the collector  14  in a circumscribing relationship about a shaft  30  (see  FIGS. 6-7 ). The aperture  15  is a smaller diameter than the rest of the collector  14  which allows for the collector  14  to be in close fit with the shaft  30 . The collector  14  has a funnel  26  which is used to collect lubricant. The funnel  26  has a top portion that has a wide diameter with tapered walls that extend downward, thus allowing the funnel  26  to more effectively catch lubricant and gather it at a smaller diameter neck of the funnel  26 . An inlet port  18  is connected at a perpendicular angle at the bottom of the smaller diameter neck of the funnel  26 . The inlet port  18  allows the lubricant to be delivered through the wall of the collector  14  for introduction to the pump member  16  which is contained by the pump housing  12 .  
         [0018]     The pump housing  12  has an aperture  13  that is used to mount the pump housing  12  to the shaft  30  in a circumscribing fashion. The pump housing  12  also has a collar  40  which has a diameter that is smaller than the pump housing  12 . The collar  40  allows the pump housing  12  to encase a rotating pump member  16 . The pump housing  12  has four discharge cavities  20  which are separated by four ribs  21 . At the discharge cavities  20  pressurized lubricant is collected prior to leaving the pump housing  12 . While this particular embodiment describes four discharge cavities  20  and four ribs  21 , a greater or lesser number of discharge cavities  20  or ribs  21  can be used depending on the needs of the particular application. For example, a smaller pump housing  12  may require a lesser number of discharge cavities  20  and ribs  21  than a housing that is larger in size.  
         [0019]     The pump member  16  has an aperture  17  that is used to mount the pump member  16  to the shaft  30  in a circumscribing fashion so that the pump member  16  will rotate with the shaft  30 . The pump member  16  also has a collared portion  42  that is smaller in diameter than the rest of the pump member  16 , thus allowing the pump member  16  to have a greater area of support on the shaft  30  and be capable of sliding into the aperture  15  of the collector  14 . This improves stability as the pump member  16  rotates with the shaft  30 . The pump member  16  is rotatably contained within the housing  12  and is positioned between the inlet port  18  and the discharge cavities  20 . The pump member  16  has an impeller face  24  which receives lubricant from the inlet port  18 . As lubricant contacts the impeller face  24 , centrifugal force caused by the rotation of the pump member  16  causes the lubricant to move to the outer circumference of the impeller face  24 . When lubricant reaches the outer perimeter of the impeller face  24  it is delivered to a radially outer surface of the pump member  16 . The radially outer surface includes at least one and preferably a plurality of helically extending surfaces or helical grooves  22 , forming a very coarse series of truncated insert threads. The threads are either recessed into the surface or they can be extended away from the surface. The rotation of the pump member  16  causes the lubricant to move along the helical grooves  22 . The lubricant moves in a longitudinal direction along the axis of the pump member  16  toward the discharge cavities  20  of the pump housing  12 . Note that the four ribs  21  on the pump housing  12  form a gap between the wall of the pump housing  12  and the pump member  16 . The rotation of the pump member  16  causes the movement of fluid along the grooves  22  located on the surface which causes the lubricant to become pressurized.  
         [0020]     The impeller face  24  on the pump member  16  initially accelerates the movement of lubricant from the inlet port  18  to the helical grooves  22  of the pump member  16 . This is helpful from the standpoint that the lubricant at the inlet port  18  is not pressurized and therefore the use of the impeller face  24  acts as a centrifugal pump to quickly accelerate the lubricant to the surface  22 . However, the use of an impeller face  24  is not completely necessary for the operation of the pump arrangement  10 . It is possible for the lubricant to be moved using a pump member  16  that just has the surface with one or more helical insert threads  22  and does not have an impeller face  24 . Likewise it is also within the scope of this invention to have a pump member  16  that only has the impeller face  24  without one or more helical threads.  
         [0021]     While this particular embodiment of the invention describes the collector  14  and the pump housing  12  as being two separate connectable structures, it is possible to have the structures be more integrated with each other. For example, the wall of the pump housing  12  can be integrated with the collector  14  so that the pump member  16  is rotatably disposed within the boundaries of the collector  14 , rather than the boundaries of the pump housing  12  as described above. The pump housing  12  can be modified to serve as a plug member allowing the pump member  16  to be inserted within the collector  14 .  FIG. 6  is a cross-sectional view of the pump arrangement  10  in operation within a gear box housing  28 . The gear box housing  28  as used herein is not to be limited to housings that only have moveable gear members, rather the term “gear box” as used herein encompasses all mechanical assemblies used for the transmission of power in an automotive power train. In the present embodiment the gear box  28  is a transfer case housing incorporating the pump arrangement  10 . The pump arrangement  10  can also be used in combination with other types of systems such as differentials, transmissions, generators or virtually any system where lubricant needs to be pumped throughout the system.  
         [0022]     The pump arrangement  10  is positioned on a shaft  30 , which in this case is a rear output shaft of a vehicle driveline. However, the pump arrangement  10  can be incorporated on virtually any type of shaft where lubrication is needed, such as transfer case input or output shafts. The pump arrangement can also be used on shafts for power generators, vehicle differentials, motorcycle shaft drives and vehicle transmissions.  
         [0023]     The shaft  30  extends through the apertures  13 ,  15 ,  17  of the various components of the pump arrangement  10 . The pump member  16  is connected to and rotates with the shaft  30 , while the pump housing  12  and collector  14  are connected together and fastened to the gear box housing  28  in a stationary manner using a mounting flange  38 . The mounting flange  38  is a portion of the collector  14  that protrudes from the top of the funnel portion  26  to allow the collector  14  to be fastened in a stationary manner to the gear box housing  28 .  
         [0024]     A longitudinal bore  44  extends through the shaft  30 . The longitudinal bore  44  is used to move lubricant to various locations throughout the gear box housing  28 . Along the length of the longitudinal bore  44  there is a radial bore  34  that extends perpendicular from the longitudinal bore  44  to the surface of the shaft  30 . The radial bore  34  is used to deliver lubricant to selected portions throughout the gear box housing  28 . While  FIG. 6  only shows one radial bore  34 , there can be more than one radial bore  34  present along the length of the shaft  30 .  
         [0025]     In operation, the pump arrangement  10  operates in the following manner. The gear box housing  28  contains moving components that have lubricant on their surfaces. As shown in  FIG. 6 , the shaft  30  has lubricant on its surface that reduces friction during the rotation of the shaft  30 . A sprocket  46  and chain  48  rotate about the shaft  30 . Both the sprocket  46  and chain  48  are covered in lubricant, because as the chain  48  rotates, the slack from the chain  48  is passed through a lubrication sump (not shown) at the bottom of the gear box housing  28 . The high speed of rotation of the shaft  30 , sprocket  46  and chain  48  causes lubricant to fly off of these components and onto the inside surface of the gear box housing  28 . Gravity then causes the lubricant to drip down the inside surface of the gear box housing  28 . As gravity pulls the lubricant downward it gets collected in a lubrication furrow  36  (shown in  FIG. 7 ) that is formed on the inside surface of the gear box housing  28 . The lubrication furrow  36  directs the lubricant toward a collection wall  50  that empties into the funnel  26  of the collector  14 . The lubricant is then collected at the base of the funnel  26  and is introduced into the pump arrangement  10  through the inlet port  18 .  
         [0026]     The rotating shaft  30  and pump member  16  draw in the lubricant through the inlet  18  using the impeller face  24 . The impeller face  24  has grooves  25  which move the lubricant using centrifugal force. When the lubricant reaches the outer diameter of the impeller face  24 , the lubricant moves longitudinally along the surface  22  of the pump member  16 . The lubricant becomes pressurized as it moves from the inlet  18  to the end of the surface  22  of the pump member  16 .  
         [0027]     The pressurized lubricant moves off the screw pump  16  and is collected in the discharge cavities  20 . The discharge cavities  20  allow the pressurized lubricant to be collected where it then enters the longitudinal bore  44  of the shaft  30  using a bore input port  52 . At this point the lubricant is delivered and recirculated in the same manner described above.  
         [0028]     As the shaft  30  rotates, a certain amount of back pressure can be produced from the bore input port  52  which is caused by centrifugal force occurring within the bore input port  52 . The discharge cavities  20  allow lubricant to collect and build pressure to overcome any back pressure formed in the bore input port  52 .  
         [0029]     Referring to  FIG. 7 a  cross-sectional view taken about sections lines  7 - 7  on  FIG. 6  can be seen. The pump arrangement  10  is shown to be mounted on the shaft  30  all of which are located inside of the transfer case housing  28 . The transfer case housing has a lubrication furrow  36  which extends in a generally parallel fashion to the shaft  30 . As described in detail above, the lubrication furrow  36  functions to collect lubricant that is propelled from the various components inside of the transfer case housing  28 .  
         [0030]      FIG. 8  is a cross-sectional overhead view of a pump arrangement  100  incorporating an alternate embodiment of the invention. This particular embodiment of the invention has a pump housing  102  having at least one helically extending pumping surface  104  located on an interior surface  105  of the pump housing  102 . A pump rotational member  106  has a smooth surface that is positioned adjacent the interior surface  105  of the pump housing  102 . As the rotational pump member  106  rotates with the shaft  30  fluid will be pressurized and moved through the pump housing  102  along the surface  104 .  
         [0031]     The description of the invention is merely exemplary in nature and, thus, 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.