Abstract:
A component surrounding an axis for directing fluid along a flow path in a transmission for a motor vehicle. The component includes a first wall having a thickness formed with an inner surface facing the axis, and a hole spaced about the axis and extending through the thickness of the wall, and a channel formed in the wall, communicating with the hole and the inner surface, including a base having a length that extends angularly about the axis, and having a depth that increases along the length as distance from the hole decreases.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to supplying hydraulic fluid, such as lubricant, to a component and, in particular, to a fluid flow path in a rotating hub of clutch for a motor vehicle transmission. 
   2. Description of the Prior Art 
   The hub of a friction clutch or an overrunning clutch in an automatic transmission assembly transfers torque between an element of the clutch element and a shaft or another component that transmits torque in the assembly. In addition, such hubs carry hydraulic fluid, such as automatic transmission fluid (ATF), to lubricate and cool surfaces of the clutch, especially those surfaces that are subject to friction, fretting or chafing during in-service use. To provide fluid passageways, the hub is usually formed with a series of angularly spaced holes drilled radially through the hub thickness, through which holes fluid passes to the critical surfaces of the component. ATF fluid is continually deposited by being thrown radially outward against the inner surface of the component as the assembly operates. 
   Typically, hubs that are machined from a solid metal blank or forging, or by another forming method other than sheet metal forming, require machining an oil dam on the inner diameter of the hub to direct oil through radial drilled holes in order to cool the clutch and to prevent oil flow from the ends of the hub. Oil dams are, however, expensive to machine in such hubs. 
   Axially directed slots located at each radial hole are ineffective toward directing a sufficient volume of oil from the inside diameter of the hub to the radial holes because oil delivered to the hub inner diameter along the circumferential length of the hub between the slots will run off the end of the hub instead of flowing into the axial slots and radial holes. 
   There is a need in the industry, therefore, for a low cost technique that efficiently and effectively gathers and transports oil from the inner circumference of a hub to and through holes that pass through the wall thickness of a hub to facilitate lubrication and cooling of the critical surface of the component. 
   SUMMARY OF THE INVENTION 
   The hub is formed with a series of fluid channels, each having a base located at the inner radial surface of the hub where ATF, or another hydraulic fluid, is continually deposited by being thrown radially outward as the assembly rotates. Each channel has a base, whose contour collects oil along substantially the entire angular length of the inner surface between adjacent channels. The channels are formed such that they eliminate or reduce the need for machining the inner surface of the hub or race of an overrunning clutch. 
   Rather than using axial slots, the profile of each channel&#39;s base has the appearance of a cam, similar to that of a ratcheting, mechanical one-way clutch. The channel base directs oil to the major diameter of the channel, where a radial lube hole is located such that all oil delivered to the hub inner diameter is directed through the radial oil holes instead of only that portion of the oil contained in axial slots having a narrow angular length. 
   The contour of the channel&#39;s base is uniquely formed to operate with hubs that rotate in one direction only so that the end of the channel terminates at a radial hole and the depth of the channel is a maximum at the hole. Alternately, the contour of the channel&#39;s base extends is opposite angular direction from its respective hole to accommodate hubs that rotate in opposite directions. Similarly in this instance, the end of the channel terminates at a radial hole and the depth of the channel is a maximum at the hole. 
   A component, surrounding an axis for directing fluid along a flow path in a transmission for a motor vehicle, includes a first wall having a thickness formed with an inner surface facing the axis, and a hole spaced about the axis and extending through the thickness of the wall. A channel formed in the wall, communicates with the hole and the inner surface. The channel includes a base having a length that extends angularly about the axis, and a depth that increases along the length as distance from the hole decreases. 
   The scope of applicability of the preferred embodiment will become apparent from the following detailed description, claims and drawings. It should be understood, that the description and specific examples, although indicating preferred embodiments of the invention, are given by way of illustration only. Various changes and modifications to the described embodiments and examples will become apparent to those skilled in the art. 

   
     DESCRIPTION OF THE DRAWINGS 
     These and other advantages will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: 
       FIG. 1  is a side view showing a hydraulically actuated clutch and servo in an automatic transmission assembly; 
       FIG. 2  is an isometric view of a clutch ring illustrating its hub and inner surfaces; 
       FIG. 3  is an end view of a clutch component showing a fluid channel; 
       FIG. 4  is a cross section taken at plane  4 - 4  of  FIG. 3 ; 
       FIG. 5  is an end view of a component showing an alternate fluid channel; 
       FIG. 6  is a cross section taken at plane  6 - 6  of  FIG. 5 ; 
       FIG. 7  is a partial isometric view illustrating the fluid channel of  FIG. 3  formed on the inner surfaces of a clutch ring; and 
       FIG. 8  is a partial isometric view illustrating the fluid channel of  FIG. 4  formed on the inner surfaces of a clutch ring. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring first to  FIG. 1 , a clutch  10  for alternately opening and closing a drive connection between a hub  12  and a drum member (also called a clutch cylinder)  14  in a hydraulically-actuated automatic transmission includes clutch plates  16 , mutually spaced axially along the drum  14 . The radial outer periphery of the plates  16  are connected to the drum by a spline  17  formed on the inner surface of drum  14 , such that the plates and drum rotate as a unit. Located between each of the plates  16  is a friction disc  18 , which is connected to the hub  12  by a spline  19  formed on the radial outer surface of the hub, such that the discs and hub rotate as a unit. The hub  12  is supported on a bearing  20  and is formed with a series of angularly-spaced radial holes  22 , through which hydraulic fluid passes radially outward to the friction discs  18  and plates  16 . The clutch is substantially symmetric about a longitudinal axis  23   
   The clutch plates  16  and friction discs  18  are forced into mutual frictional content by movement of a servo piston  24 , located in a cylinder defined by drum  14 . Chamber  26  is supplied with a pressurized hydraulic fluid through a passage  28  and check valve  30 . When cylinder  26  is pressurized, piston  24  moves rightward forcing plates  16  and discs  18  against a pressure plate  32 , which is engaged with spline  17  and is secured by a snap ring  34  to the drum  14 . In this way, plates  16  and discs  18  produce a drive connection between hub  12  and drum  14 . A return spring  36  continually applies to piston  24  a force that resists its movement rightward and causes the piston to move leftward to the position shown in  FIG. 1 , when pressure in cylinder  26  is low. The position of compression return spring  36  is fixed by a plate  38 , which is secured by a snap ring  40  to a hub  42 . A check valve  30  allows oil to exit the chamber  26  when pressure is low to reduce centrifugal forces from the residual oil in the chamber and ensure leftward movement of the piston  24  when intended. 
     FIG. 2  is an isometric view of a ring for a one-way clutch. The ring  50  includes a hub  52 , which extends angularly about axis  23 , the hub being formed with angularly-spaced axial holes  56  and a large central hole  57 . A portion of the outer surface of ring  50  is formed with axially directed spline teeth  58 , similar to the spline teeth  17 ,  19 , which driveably connect the plates  16  and discs  18  of clutch  10  to the drum  14  and hub  10 . Another portion of the outer surface of ring  50  is formed with cam surfaces  60 , which can be engaged by rockers of a one-way clutch, such as those described and illustrated in U.S. Pat. No. 7,100,756. Extending axially parallel to axis  23  and located on the radial inner surface opposite spline  58  is a surface  60  formed with profiles, which are described in detail with reference to  FIGS. 3-6 . A series of angularly spaced radial holes  80  pass through the axial wall  74 ,  94 . 
   Referring next to  FIGS. 3 and 4 , a clutch ring component  70  arranged about the central axis  23 , includes a wall  74 , which extends radially with respect to the axis between an inner surface  76 , which faces the axis, and an outer surface  78 . A series of radial holes  80 , mutually angularly spaced about axis  72 , extend through the wall  74 . 
   Fluid channels  82 , formed in the wall  74 , are mutually spaced about axis  23 . Each channel  82  includes a base  84 , which extends angularly toward a respective hole  80 . The depth of each channel  82 , as measured by the radial distance between the inner surface  76  and the base  84 , increases as the angular distance along the base from the respective hole  80  decreases. The depth of each channel  82  is a maximum at the respective hole  80 . 
   The base  84  of each channel  82  terminates at a surface  86 , which intersects both the base and the inner surface  76 . Each channel  82  communicates with the respective hole  80 . As  FIG. 4  illustrates, at one end face  87  of wall  74 , each channel  82  is closed by the radial hub  52 . At the opposite axial end of face  88 , each channel  82  is open to permit tool extraction so that these features can be formed by the initial manufacturing process. 
   In operation, preferably component  70  rotates counterclockwise about axis  23 . Hydraulic fluid, thrown radially outward against inner surface  76  as the component  70  rotates, enters each channel  82  along its entire angular length between adjacent holes  80 , flows in the channel toward and through the respective hole at the end of the channel  82 . 
   Referring to  FIGS. 5 and 6 , a clutch ring component  90  arranged about the central axis  23 , includes a wall  94 , which extends radially with respect to the axis between an inner surface  96 , which faces the axis, and an outer surface  98 . A series of holes  80 , mutually angularly spaced about axis  23 , extend radially through the wall  94 . 
   Fluid channels  102 , formed in the wall  94 , are mutually spaced about axis  23 . Each channel  102  includes a base  104 , which extends angularly toward a respective hole  80 . The base  104  of each channel  82  extends angularly on both sides of a radial line, which extends from axis  23  through the center of each hole  80 , from the base of an adjacent channel to the hole of the subject channel. The depth of each channel  102 , as measured by the radial distance between inner surface  96  and the base  104 , increases as the angular distance along the base from the respective hole  80  decreases. The depth of each channel  102  is a maximum at the respective hole  80 . 
   Each channel  102  communicates with its respective hole  80 . As  FIG. 6  illustrates, at one end face  108  of wall  94 , each channel  102  is closed by radial hub  52 . At the opposite axial end face  112 , each channel  102  is open to permit fluid to flow into the channel along its length toward the hole  80  and though the hole to the outer surface  98 . 
   In operation, component  90  rotates in either direction about axis  72 . Hydraulic fluid, thrown radially outward against inner surface  96  as component  90  rotates, enters each channel  102  along its entire angular length between adjacent holes  80 , flows in the channel in both angular directions toward and through the respective hole  80  at the end of the channel  82 . 
   In accordance with the provisions of the patent statutes, the preferred embodiment has been described. However, it should be noted that the alternate embodiments can be practiced otherwise than as specifically illustrated and described.