Abstract:
Clutches require fluid passages to be contained therein to lubricate the moving parts therein. Current clutch designs requiring fluid passages to be formed through the spline provides numerous difficulties. The present clutch design and method of assembling the clutch comprises a clutch housing having a predetermined shape, a piston positioned within the clutch housing, a sleeve having a predetermined shape substantially conforming to the predetermined shape of the clutch housing, the sleeve being positioned within the clutch housing forming a fluid passageway between the clutch housing and the sleeve and forming a piston reactive cavity between the clutch housing, the piston, and the sleeve.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority from U.S. Provisional Patent Application No. 60/457,422 filed on Mar. 25, 2003, which is hereby incorporated by reference herein. 
     
    
     
       FIELD OF INVENTION  
         [0002]    The present invention relates generally to clutches, and in particular, to clutch housings with a multi-function hydraulic sleeve.  
         BACKGROUND  
         [0003]    As shown in the current design of FIG. 1, one skilled in the art will recognize the portion of the clutch housing referred to as the spline  10  having fluid passages  12 ,  14 , and  16  positioned therein. These fluid passages  12 ,  14 , and  16  provide fluid pressure to the piston reactive cavity  18 . Such action causes engagement of the friction clutch plates  20  so that torque is transferred from the drive unit to the transmission.  
           [0004]    It is well known, however, that the manufacture of that design is difficult for numerous reasons. Particularly, during manufacture of the spline  10 , it is difficult for the fluid passages  12 ,  14 , and  16  to hold their shape in response to the heat treatment required during manufacture. Further, the deburring steps can be difficult and costly to accomplish. Thus, the nature of the design requiring fluid passages to be formed through the spline provides numerous difficulties.  
           [0005]    It is an object of the present invention to reduce the manufacturing complexity and reduce total cost associated with the manufacture of the clutch. The present invention will also improve the clutch by eliminating the need for intersecting holes or passages and the complex issues associated with deburring them. Further, the present invention will provide improved fluid flow into the piston reactive cavity and will provide a sealing surface so that the piston can act as a cavity seal. Finally, the present invention will provide a method of self-retention of the sleeve as well as providing a means for retaining the centrifugal compensation device.  
         SUMMARY OF THE INVENTION  
         [0006]    In accordance with the present invention there is provided a clutch that comprises: a clutch housing having a predetermined shape, a piston positioned within the clutch housing, a sleeve having a predetermined shape substantially conforming to the predetermined shape of the clutch housing, the sleeve being positioned within the clutch housing forming a fluid passageway between the clutch housing and the sleeve and forming a piston reactive cavity between the clutch housing, the piston, and the sleeve.  
           [0007]    In accordance with the present invention there is further provided a method of assembling a clutch, comprising: providing a clutch housing having a predetermined shape, attaching a piston within said clutch housing, providing a sleeve having a shape substantially conforming to the predetermined shape of the clutch housing, and positioning the sleeve within said clutch housing such that a fluid passageway is formed between the clutch housing and the sleeve and such that a piston reactive cavity is formed between the clutch housing, the piston, and the sleeve.  
           [0008]    The present invention will be more fully described in the following written description with reference to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0009]    Objects and advantages together with the operation of the invention may be better understood by reference to the following detailed description taken in connection with the following illustrations, wherein:  
         [0010]    [0010]FIG. 1 is a diagrammatic cross-sectional view of the current design utilized in the art;  
         [0011]    [0011]FIG. 2 is a cross-sectional view of the design of the clutch of the present invention;  
         [0012]    [0012]FIG. 3 is a diagrammatic cross-sectional and top-half view of the design of the clutch of the present invention; and  
         [0013]    [0013]FIG. 4 is a cross-sectional, more detailed view of the sleeve of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]    Reference is now made to the drawings to further describe the present invention, wherein like characters represent the same or corresponding parts throughout the several views. There is seen in FIG. 2 a clutch generally designated as  30 . The clutch  30  includes a clutch housing  34 , a portion of which is referred to as a spline  38 , a piston  42 , a hydraulic sleeve  46 , a snap ring  50 , a centrifugal compensation device  54 , a set of springs  58 , and friction clutch plates  62 .  
         [0015]    As can best be seen in FIG. 2, the clutch housing  34  has a predetermined shape. It has the spline  38 , a first stepped portion  66 , and a second stepped portion  70 . The spline  38  mates with a transmission (not shown) and the second stepped portion  70  mates with an engine (not shown) in order to operate the clutch  30 . Further, the spline  38  has a fluid entry passage  74  so that during operation of the clutch  30  fluid, like oil, can flow from the transmission into the clutch  30  through the fluid entry passage  74 .  
         [0016]    The sleeve  46  is positioned within the clutch housing  34 . The sleeve  46  and the clutch housing  34  form a fluid passageway  78 . The fluid passageway  78  permits fluid to travel from the fluid entry passage  74 , through the fluid passageway  78 , and into a piston reactive cavity  82 , described in more detail below. More particularly, the sleeve  46  has an outer surface  86 . The clutch housing  34  has an inner surface  90 . The sleeve  46  is positioned within the clutch housing  34  forming a space between the outer surface  86  of the sleeve  46  and the inner surface  90  of the clutch housing  34 . This space is the fluid passageway  78 .  
         [0017]    As can best be seen in FIG. 4, the sleeve  46  is generally tubular and has a predetermined shape substantially similar to the predetermined shape of the clutch housing  34 . The sleeve  46  has a first portion such as a straight tubular portion  94 , a first stepped portion  98 , and a second stepped portion  102 . The straight tubular portion  94  and the first stepped portion  98  form the fluid passageway  78  described above.  
         [0018]    Between the tubular portion  94  and the first stepped portion  98  is a snap ring flange  106 . The snap ring flange  106  holds the snap ring  50  in place. It prevents the snap ring  50  from being pushed out of place during operation of the clutch  30 . The snap ring flange  106  is shaped to lock the snap ring  50  in place. The snap ring  50 , when locked in the snap ring flange  106 , can withstand the operational fluid pressures placed upon it during operation of the clutch  30  without falling out. The snap ring  50  itself is a fail safe. It permits the sleeve  46  to maintain its proper position within the clutch housing  34  even if the interference fit between the sleeve  46  and the clutch housing  34  is not maintained.  
         [0019]    As stated previously, during operation of the clutch  30 , fluid travels into the fluid entry passage  74 , through the fluid passageway  78 , and into the piston reactive cavity  82 . The piston reactive cavity is formed by the clutch housing  34 , the piston  42 , and the sleeve  46 . The first stepped portion  98  of the sleeve has a sealing surface  110  thereon. The piston  42  is in sealing engagement with the sealing surface  110 , forming a portion of the piston reactive cavity  82 . As discussed in more detail below, the material the sleeve  46  is composed of is sufficiently void of irregularities so that the piston  42  can create a seal with the sealing surface  110  of the sleeve  46 . It is, therefore, not necessary to machine the sealing surface  110  to remove any irregularities. Further, the first stepped portion  98  and the piston  42  are positioned within the clutch housing  34  such that the piston reactive cavity  82  is formed without the necessity of drilling additional holes in the clutch housing  34 .  
         [0020]    The second stepped portion  102  of the sleeve  46  has a centrifugal retaining device  114  therein. The centrifugal retaining device  114  retains the centrifugal compensation device  54  within the clutch housing  34  during operation of the clutch  30 . The centrifugal compensation device  54  helps the piston  42  remain in its proper position within the clutch housing  34  during operation of the clutch  30 .  
         [0021]    Finally, the sleeve  46  has an interior surface  118 . The interior surface  118  contacts a sleeve bearing  122  that is contained within the sleeve  46 . The sleeve bearing  122  absorbs the relative motion of the shaft (not shown) of the transmission (not shown). In particular, the sleeve bearing  122  is made of a softer material with lubricating fluid flowing therethrough so as to provide lubrication for the sleeve  46  and the shaft. The sleeve bearing  122  may be a separate component from the sleeve  46 , or, alternatively, it may be an integral part of the sleeve  46 .  
         [0022]    In order to assemble the clutch  30 , the clutch housing  34  having the predetermined shape and a fluid entry passage  74  therein is provided. The piston  42  is then inserted into the clutch housing  34  and is attached thereto. The sleeve  46  is then positioned within the clutch housing  34  so that the outer surface  86  of the sleeve  46  is below the inner surface  90  of the clutch housing  34  forming the fluid passageway  78 . The sleeve  46  is positioned within the clutch housing  34  until it is sealingly engaged with the clutch housing  34  by an interference fit thereby providing a sleeve retaining feature interference fit  126  as is best seen in FIG. 3.  
         [0023]    Further, the first stepped portion  98  of the sleeve  46  is positioned relative to the piston  42  and the clutch housing  34  so as to form the piston reactive cavity  82 . The contact of the piston  42  and the sealing surface  110  of the first stepped portion  98  creates the seal for the piston reactive cavity  82  substantially sealing fluid therein. The sealing surface  110  and the piston  42  are substantially sealed without the necessity of machining the sealing surface  110  due primarily to the composition of the sleeve  46 .  
         [0024]    The sleeve  46  is composed of a powered metal material such as sintered iron. It should be understood, however, that the composition of the sleeve  46  is not limited to powered metal, but may also include other materials such as aluminum, steel, ceramic, etc. The sleeve  46  being composed of powered metal causes the sealing surface  110  to be void of irregularities and as such creates an excellent sealing surface. Further, the sleeve  46  being composed of powered metal makes it unnecessary to machine the sealing surface  110 . Reducing the manufacturing and assembly costs of the clutch  30 .  
         [0025]    Thus, through the current design, the present invention eliminates two sets of three intersecting holes and a sealing plug. Further, the sleeve  46  of the present invention can improve the fluid flow to the piston reactive cavity  82  because the fluid no longer needs to flow through a machined passageway.  
         [0026]    The invention has been described above and, obviously, modifications and alternations will occur to others upon a reading and understanding of this specification. In addition, the method of assembly described above is not limited to the order in which the steps above are recited. The claims as follows are intended to include all modifications and alterations insofar as they come within the scope of the claims or the equivalent thereof.