Patent Publication Number: US-2007107787-A1

Title: Rotary shift valve for automatic transmission systems

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is related to, and claims the benefit of priority from, Provisional Application Ser. No. 60/737,550, filed Nov. 17, 2005. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
      Not applicable.  
     INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC  
      Not applicable.  
     FIELD OF THE INVENTION  
      The present invention relates to the field of valves for selectively porting a fluid through one or more outlets, and more particularly to such a valve comprising a housing having an interior cavity in which is rotatably disposed an inner member having an interior cavity for holding a fluid. The inner member is selectively rotatable relative to the housing to selectively bring at least one outlet passageway defined therethrough into communication with at least one passageway defined through the housing, thus permitting selective communication of a fluid from the interior cavity of the inner member to the exterior of the housing, and thence to one or more downstream elements which may be actuated by such fluid.  
     BACKGROUND OF THE INVENTION  
      Automatic transmissions are apparatus used to change the gearing ratios between an engine and the drive axles in a motor vehicle, in order to provide the torque needed to start the vehicle from a stop, accelerate the vehicle from a slower speed to a faster speed, or to enable the vehicle to climb grades or carry or tow heavy loads, as well as to provide ratios needed for the vehicle to attain and maintain higher speeds and to realize desirable fuel economy, engine noise levels, and to minimize engine wear.  
      Automatic transmissions function through clutches which are activated or deactivated by the application, through a shift valve, of hydraulic pressure to activators for the appropriate clutches. The shift valve is itself controlled by a computer controller, and/or by a system of sensors and relays, which switch power between several electromagnets. In the typical shift valve, these electromagnets attract and/or repel ferrous spools to either end of a clylindrical bore in the shift valve body. Each such bore intersects with other bores, allowing hydraulic fluid to be directed through one or more ports to activate one or more clutches, depending on whether the spool has been attracted/repelled to a position covering an intersection between the valve bore and another, adjoining bore, or to a position away from such an intersection.  
      Exemplary of the foregoing types of transmissions are the disclosures of Asano et al., U.S. Pat. No. 3,707,891, and Sugano, U.S. Pat. No. 4,566,355, which disclosures are incorporated herein by reference in their entireties.  
      Unfortunately, automatic transmission shift valves of such conventional construction are attended by several considerable drawbacks. First, the size of the aluminum block required to accommodate the numerous bores needed for a typical transmission, and the electromagnetic coils required for activation (typically two electromagnets for each spool), makes these shift valves both very heavy and quite large in terms of total space required within the engine envelope. Second, in order for the shift valve to function without excessive leakage, the bores and the ferrous spools which reside therein must be very straight, cylindrical and smooth. Likewise, the manufacturing and operating tolerances of these components must be very narrow. In addition to requiring very precise manufacturing methods and procedures, the close operating tolerances also make such conventional shift valves extremely sensitive to any contamination; the presence of even very small particulates can interfere with the movement of the ferrous spools inside the bores, thus hindering or even preventing operation of the valve. In order to assure proper shift valve operation, very thorough filtration of the hydraulic fluid is thus conventionally required, and most failures of typical shift valves involve tiny particulates which escape filtration and are caught between a spool and a bore.  
      It would thus be advantageous to have an automatic transmission in which the shift valve thereof was at once relatively small and lightweight, and which required less stringent tolerances between the operating components thereof.  
     SUMMARY OF THE DISCLOSURE  
      The present invention encompasses improvements to the prior art by providing a valve for selectively porting a fluid through one or more outlets, the valve comprising a housing having an exterior, an interior cavity, and at least one outlet passageway defined through the housing. The outlet passageway communicates the interior cavity to the exterior of the housing through an outlet opening. The inventive valve further includes an inner member disposed within the interior cavity of the housing and selectively moveable relative thereto, the inner member having an exterior, an interior cavity for holding a fluid, and at least one outlet passageway defined through the inner member and communicating the interior cavity to the exterior of the inner member through an outlet opening. To communicate a fluid from outside the housing to the interior cavity of the inner member, there is further provided at least one inlet passageway defined through each of the inner member and the housing. By selective movement of the inner member relative to the housing, the at least one outlet passageway and outlet opening of the inner member may be brought into (and out of) communication with the at least one outlet passageway defined through the housing, thereby permitting selective communication of a fluid from the interior cavity of the inner member to the exterior of the housing via the communicating outlet passageways.  
      According to one embodiment of the present invention, the at least one outlet opening of the inner member is characterized by a varying geometry. By selective movement of the inner member relative to the housing, the at least one outlet opening of the inner member may be brought into communication with the at least one outlet passageway defined through the housing in a plurality of orientations, each of which permits a different rate of fluid flow from the interior cavity of the inner member to the exterior of the housing via the communicating outlet passageways.  
      In another embodiment, the at least one outlet opening of the inner member and the at least one outlet passageway of the inner member are characterized by generally constant geometries. By selective movement of the inner member relative to the housing, the at least one outlet opening of the inner member may be brought into communication with the at least one outlet passageway defined through the housing in single orientation which permits a relatively constant rate of fluid flow from the interior cavity of the inner member to the exterior of the housing via the communicating outlet passageways.  
      According to another feature of the present invention, at least one raised projection is provided on the exterior of the inner member, the at least one outlet opening of the inner member being defined in the at least one raised projection.  
      Per yet another aspect of the instant invention, the inner member may be elastically expandable radially outwardly under the pressure of a fluid disposed in the inner member interior cavity so as to bring the at least one raised projection into sealing contact with the housing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and other features of the instant invention will be better understood with reference to the following description and accompanying drawings, of which:  
       FIG. 1  is an exploded perspective view of the valve of the present invention according to a first embodiment thereof;  
       FIG. 2  is a partial cut away, perspective view of the valve of the present invention;  
       FIG. 3  is an exploded perspective view of the housing portion of the valve of the present invention, according to a second embodiment thereof;  
       FIG. 4  is a detailed cross-sectional view depicting the inventive valve of one embodiment thereof under operating conditions, wherein the inner member is rotated to bring an outlet opening and associated outlet passageway thereof into alignment with an outlet passageway defined through the housing portion;  
       FIG. 5  is a detailed cross-sectional view depicting one alternative arrangement for communicating a fluid to the interior cavity of the inner member of the inventive valve;  
       FIG. 6  is an exploded perspective view of the inner member of the valve of the present invention, according to a second embodiment thereof;  
       FIG. 7  is an exploded perspective view of the inner member of the valve of the present invention, according to a third embodiment thereof;  
       FIG. 8  is a detailed perspective view of an alternative configuration of the inner member outlet opening;  
       FIGS. 9 and 10  are detailed cross-sectional views illustrating exemplary operation of the outlet passageways and outlet opening of the alternative configuration of  FIG. 8 ;  
       FIG. 11  is an exploded perspective view of the valve of the present invention according an alternative embodiment thereof incorporating the outlet openings of  FIG. 8 ;  
       FIG. 12  is a perspective view of an alternative embodiment of the inventive valve, according to which at least one pair of outlet openings are provided in longitudinal alignment to effect the simultaneous porting of a fluid through plural outlet passageways;  
       FIG. 13  is a detailed cross-sectional view of an inventive valve according to one embodiment thereof, wherein means are provided for directing a lubricant between the inner member and the housing portion; and  
       FIG. 14  is a schematic representation of the present invention in an operational environment wherein the inventive valve functions as a shift valve for a motor vehicle automatic transmission. 
    
    
     WRITTEN DESCRIPTION  
      Referring now to the drawings, and more specifically to  FIGS. 1 and 2 , the present invention will be seen to generally comprise, in a first exemplary embodiment thereof, a valve for selectively porting a fluid through one or more outlets, and thence to one or more downstream elements which may be actuated by such fluid (including, for instance, clutches), the valve including: First, a housing  5  having an interior cavity  6 , and at least one passageway  7  defined through the housing  5 , such passageway  7  communicating the interior cavity  6  ( FIG. 2 ) through at least one outlet opening (indicated generally at  8 ) to the exterior of the housing  5 ; and, second, an inner member  30  moveably disposed within the interior cavity  6  of the housing  5  and selectively moveable relative to the housing  5 , the inner member  30  having an interior cavity  31  for holding a fluid, such as, for instance, hydraulic fluid for an automatic transmission system, and at least one passageway  32  defined through the inner member  30  and communicating the interior cavity  31  of the inner member through at least one outlet opening  33  to the exterior of the inner member  30 . Such a valve as disclosed herein is especially, though not exclusively, suited for operation as a shift valve for a motor vehicle automatic transmission.  
      With continuing reference being had to  FIGS. 1 and 2 , at least one inlet passageway  9  and  34  is further defined through each of the housing  5  and inner member  30 , respectively, for communicating a fluid to the interior cavity  31  of the inner member  30 , as described in greater detail hereinbelow. Such passageways may, according to this first illustrated embodiment of the present invention, be defined coaxial with each other and the longitudinal axis of the valve. However, such configuration is not intended to be limiting of the inventive valve, and other inlet passageway configurations are thus contemplated, including, as explained further herein, inlet passageways extending radially through the housing  5  and inner member  30 .  
      Referring specifically to  FIG. 1 , housing  5  is, according to the illustrated embodiment, at least a two-part structure comprising a first housing portion  5   a  having a generally cylindrically-shaped wall  10  terminating at one longitudinal end in an end wall  11 , and terminating oppositely in an open end over which is secured a second housing portion  5   b  in the form of a cap or cover defining a further end wall  12  to thus close the housing  5  and define the cavity  6  interiorly thereof.  
      According to this first embodiment, the second housing portion  5   b includes external threads  13 , so as to permit threading securement to the correspondingly threaded  14  interior surface of the wall  10  proximate the open end of the first housing portion  5   a . However, such manner of attachment of the second housing portion  5   b to the first housing portion  5   a  is not intended to be limiting of the invention and, according to a second embodiment of the housing shown in  FIG. 3 , second housing portion  5   b ′ may be press-fit into engagement with the first housing portion  5   a ′. More particularly, second housing portion  5   b ′ of this alternate embodiment comprises a plurality of projections  15  spaced apart about the circumference of the housing portion  5   b ′ end wall  12 ′, each such projection  15  extending in a first direction from the plane of the end wall  12 ′. Each projection  15  includes a plurality of teeth  16  arranged seriatim along the length thereof and projecting radially inwardly towards the center of the second housing portion  5   b ′. The teeth  16  are each engageable with one of a plurality of annular grooves  17  defined about the exterior circumference of the first housing portion  5   a ′ wall  10 ′, each such groove having a cross-sectional shape complimentary to the cross-sectional shape of the teeth  16 . According to the illustrated embodiment, the teeth  16  and grooves  17  are characterized by a “buttress thread” type cross-sectional shape.  
      According to either of the foregoing embodiments, the second housing portions  5   b ,  5   b ′ will be seen to include a stem  18 ,  18 ′, respectively, extending from the end wall  12 ,  12 ′ thereof and arranged coaxial with the longitudinal axis of the housing  5 ,  5 ′. The stem comprises a cylindrical member through which extends the passageway  9 ,  9 ′.  
      Referring specifically to the embodiment of  FIGS. 1 and 2  as being exemplary of the others in these regards, except as otherwise noted, the passageway  9  is dimensioned to rotatably receive therein a corresponding stem  35  of the inner member  30 , with such stem of the inner member being adopted for securement to an external fluid supply, such as through the illustrated threads  36 , for instance, so as to communicate a fluid through passageway  34  to the interior cavity  31  of the inner member  30 . These means of communicating a fluid to the inner member may be eliminated in favor of other means including, as described further hereinbelow, the provision of radial ports provided through the housing and communicating a fluid to one or more radial channels disposed on the exterior of the inner member which convey the fluid through one or more ports therein to the interior cavity of the inner member.  
      As shown in the various illustrated embodiments, with the embodiment of  FIGS. 1 and 2  being representative, the housing  5  of the present invention is characterized by a generally cylindrical shape, wherein the exterior of the housing  5  and the interior cavity  6  are both substantially defined by the same cylindrically shaped wall  10  of the housing  5 . Of course, it is contemplated that the exterior shape of the housing  5  may be other than cylindrical, subject to user need or desire; only the interior cavity  6  needs to be generally cylindrical. Similarly, it will be appreciated from this disclosure that the inner member need not be limited to the generally cylindrical shape herein described.  
      Referring now to  FIGS. 1, 2 , and  4 , in order to permit the outer housing  5  to be mated to a manifold or distribution channel system of the type commonly incorporated into many transmission systems, housing  5 , and, more specifically, first housing portion  5   a  of the illustrated valve further includes a base comprising spaced-apart supports  19  having disposed therebetween at least one (and, as depicted, a plurality of) radially projecting conduit  20  defining a portion of the passageway  7  through the housing  5  and communicating the interior cavity  6  thereof with the outlet opening  8  defined proximate the end of each such conduit  20 . The terminal portion  21  of each such conduit  20  is further characterized by a narrower outside diameter than that of the remainder of the conduit  20 , such narrower diameter terminal portions  21  each being dimensioned to be received within a corresponding outlet opening  81  provided on a manifold  80  (see  FIG. 4 ). Sealing means, including, by way of non-limiting example, O-rings  22 , may be provided on each such terminal portion  21  to ensure sealing engagement between each terminal portion  21  and the corresponding manifold outlet into which it is received.  
      Referring also to  FIG. 5 , the foregoing base arrangement may also provide an alternative means for supplying a fluid to the interior cavity  31  of the inner member  30 . According to this arrangement, the manifold base includes at least one radially projecting inlet conduit  23  comprising a fluid inlet passageway  24  defined through the housing  5  and communicating a fluid from the manifold  80  to the interior cavity  31  of the inner member  30  via an annular groove or channel  37  defined on the exterior surface of the inner member  30  by a pair of spaced-apart, parallel annular ridges  38 . The ridges  38  are sealingly engaged with the inner surface of the housing wall  10 , for instance by means of O-rings  39  provided on each ridge  38 . The inlet conduit  23  includes, as shown, a terminal portion  25  characterized by a narrower outside diameter than that of the remainder of the conduit  23 , such narrower terminal portion  25  being dimensioned to be received within a corresponding inlet opening  82  provided on the manifold  80 . Sealing means, including, by way of non-limiting example, an o-ring  26 , may be provided on such terminal portion  25  to ensure sealing engagement between the terminal portion  25  and the corresponding manifold inlet  82  into which it is received.  
      Of course, the aforedescribed embodiments comprehend only exemplary means for connecting the valve of the present invention to a fluid supply and/or downstream elements (e.g., clutches) actuated by the inventive valve, and other such means are certainly possible and will be appreciated by those of skill in the art having the benefit of this disclosure. Those skilled in the art will appreciate that other mating interfaces may be mandated by the configuration of the manifold or channel distribution system to which the inventive device is to be connected. Thus, for instance, it is envisioned that the housing may constitute a planar bottom comprising a plurality of openings therein which communicate with corresponding openings in a manifold or channel distribution system, these corresponding openings being sealed with gaskets or the like in a compression sealing arrangement.  
      With continuing reference to  FIGS. 1 and 2  specifically, housing  5  includes a mount  27  provided on and extending from the end wall  11  for supporting manual, such as a lever, cam, etc. (not shown), or automatic, such as a motor (not shown), actuation means. Without limitation, exemplary motors may comprise a stepper motor, variable solenoid, or servo motor operative to incrementally rotatably move the inner member  30  relative to the housing  5 . Of course, those skilled in the art will appreciate that various means, both manual and automatic, may be employed to drive the selective rotational movement of the inner member  30 , and that such desired means may be both arranged relative to the housing  5  and operatively coupled to the inner member  30  in numerous ways, depending upon such considerations as the type of actuation means employed.  
      According to the several embodiments of the housing  5  as described hereinabove, the one or more components thereof may be formed from any suitably strong and rigid materials, including, by way of non-limiting example, metals such as aluminum, zinc, or magnesium, rigid polymers, including, for instance, reinforced (such as, for example, with fiberglass or carbon fiber) polymers. Relatedly, these one or more components may be formed by any conventional means, including, for instance, die-casting.  
      Still referring to  FIGS. 1 and 2 , the inner member  30 , according to a first exemplary embodiment, is shown as at least a two-part structure comprising a first inner member portion  30   a  having a generally cylindrically-shaped wall  40  terminating at one longitudinal end in an end wall  41 , and terminating oppositely in an open end over which is secured a second inner member portion  30   b  in the form of a cap or cover defining a further end wall  42  to thus close the inner member  30  and define the cavity  31  interiorly thereof. This second inner member portion  30   b  may be internally threaded (not visible) for threaded engagement with complimentary threads  43  provided on the exterior of cylindrical wall  40  proximate the open end of the first inner member portion  30   a.    
      However, such manner of attachment of the second inner member portion  30   b  to the first inner member portion  30   a  is not intended to be limiting of the invention and, according to a second embodiment of the inner member  30 ′, shown in  FIG. 6 , the second inner member portion  30   b ′ may be press-fit into engagement with the first inner member portion  30   a ′. More particularly, the second inner member portion  30   b ′ of this alternate embodiment comprises a plurality of spaced apart projections  44  arranged about the circumference of the second inner portion  30   b ′ end wall  40 ′ and extending in a first direction from the plane of the end wall  40 ′. Each such projection  44  includes a plurality of teeth  45  arranged seriatim along the length thereof and projecting radially inwardly towards the center of the second inner member portion  30   b ′. The teeth  45  are each engageable with one of a plurality of annular grooves  46  defined about the exterior circumference of the cylindrical wall  38 ′ of the first inner member portion  30   a ′, each such groove having a cross-sectional shape complimentary to the cross-sectional shape of the teeth  45 .  
      Still referring to  FIG. 6 , the second inner member portion  30   b ′ includes an annular channel  47  defined by a pair of spaced-apart, concentric annular walls. The annular channel  47  is arranged so as to oppose the opening on the first inner member portion  30   a ′, and is dimensioned receive therein the end of the cylindrical wall  40 ′ of the first inner member portion  30   a ′. To ensure sealing securement of first  30   a ′ and second  30   b ′ inner member portions, sealing means such as, for example, an O-ring (not shown) may be disposed inside the annular channel  47 .  
      In yet another embodiment, shown in  FIG. 7 , the second inner member portion  30   b ″ is welded, such as, for example, by spin-welding, sonic welding, etc., or otherwise adhered to the end of the first inner member portion  30   a ″ proximate the opening therein. More particularly, the second inner member portion  30   b ′ according to this embodiment comprises a pair of spaced-apart, concentric annular walls  48   a ,  46   b  extending in a first direction from the plane of the end wall  40 ″, these walls  48   a ,  48   b  defining therebetween an annular groove or channel  49  dimensioned to securely receive therein a portion of the cylindrical wall  38 ″ proximate the open end of the inner member  30   a″.    
      To ensure sealing between the first  30   a ″ and second  30   b ′ inner member portions, sealing means such as, for example, an O-ring (not shown) may further be disposed inside the annular groove or channel  49 .  
      Optionally, the first inner member portion  30   a ″ of the illustrated embodiment may, as shown, be characterized by a larger interior diameter  50  along a portion of the longitudinal length thereof proximate the open end, the length and diameter thereof corresponding to the longitudinal length and radial thickness of the interior wall  48   b.    
      But while the foregoing embodiments depict an inner member comprising at least a two-part structure, it is contemplated that the inner member may be monolithic, formed, for instance, by blow molding. Alternatively, it is contemplated that the inner member may be comprised of more than two parts.  
      Referring again to  FIGS. 1 and 2 , the second inner member portion  30  will be seen to include a stem  35  extending from the end wall  42  thereof and arranged coaxial with the longitudinal axis of the housing  5 . The stem  35  comprises a cylindrical member rotatably received in and extending through the passageway  9  of the second housing portion  5   b . A fluid inlet passageway  34  defined through the stem  35  communicates a fluid from a fluid supply, to which the stem may be threadingly connected via threads  36 , to the interior cavity  31  of the inner member.  
      With continuing reference to  FIGS. 1 and 2  specifically, the first inner member portion  30   a  includes a mounting element (indicated generally at  51 ) provided on and extending from the end wall  41  via which mounting element the inner member is connected to a motor (not shown) extending through the motor mount  27  of the housing  5 .  
      Of course, those skilled in the art will appreciate that various means may be employed to drive the selective rotational movement of the inner member  30 , and that such means may be both arranged relative to the housing  5  and operatively coupled to the inner member  30  in numerous ways, depending upon such considerations as the type of means employed.  
      Referring now to  FIGS. 1, 2  and  4 , at least one outlet passageway  32  is provided through the cylindrical wall  34  of the first inner member portion  30 a, such outlet passageway terminating in an outlet opening  33  to thus provide fluid communication between the interior cavity  31  and the exterior of the inner member  30 . As shown in the exemplary embodiment, a plurality of such passageways  32  and outlet openings  33  are preferably provided, each passageway extending radially relative to the longitudinal axis of the inner member so as to terminate in outlet openings arranged about the circumference of the cylindrical wall  40 . The particular arrangement of such passageways and outlet openings according to this embodiment is in a helical spiral relative to the longitudinal axis of the inner member  30 . In this fashion, and as will be better understood from the remainder of this disclosure, the arrangement of passageways  32  and the corresponding outlet openings  33  permits selective, incremental rotational movement of the inner member  30  to selectively bring a single outlet opening  33  (and its associated outlet passageway  32 ) into communication with one of the plurality of outlet passageways  7  defined through the housing  5 , thus permitting the selective communication of a fluid from the interior cavity  31  of the inner member  30  to the exterior of the housing  5  via the aligned outlet passageways  33  and  7 .  
      With continuing reference to  FIGS. 1, 2  and  4 , each outlet opening  33  of the exemplary embodiment is defined in a raised projection  50  in the form of an annular bead or nipple projecting from the exterior surface of the cylindrical wall  40 . Each such nipple is characterized by a radiused shoulder  51 , best depicted in  FIG. 4 , to limit frictional contact between the outlet opening  33  and the internal surface of the housing wall  10 , and to improve/promote sealing contact with the housing wall  10 . But while so illustrated, it will be understood that this configuration of the projection  50  is not limiting of the present invention, and that such projection may take on any of numerous shapes subject only to the need for providing substantial sealing contact between the inner member  30  and the interior surface of the housing wall  10 .  
      According to this embodiment, the outlet passageway  32  and associated opening  33  are, as shown, characterized by a relatively constant diameter, thus providing a constant velocity and volume of fluid flow from the inner member to the housing.  
      According to an alternative embodiment, shown in  FIGS. 8 through 11 , the at least one outlet passageway  132  terminates in a variably-dimensioned outlet opening  133  defined at least in part in a generally rectangularly-shaped raised projection  150  disposed on the exterior surface of the inner member  130 . The projection  150  serves the same sealing function as the annular projection  50  described in the preceding embodiments, though is differently shaped to accommodate the larger geometry of the outlet opening  133 . As particularly depicted, the outlet opening  133  is characterized by a tapered, “teardrop” plan shape, and further has a depth tapering downwardly from the upper surface of the projection  150 . The outlet passageway  132 , though shown disposed proximate the greater-dimensioned end of the outlet opening  133  in the illustrated embodiment, may be positioned anywhere along the length of the outlet opening. In providing such an outlet opening  133 , it will be appreciated that the velocity of the fluid from the inner member  130  to the housing (not shown) may be varied, according to Bernoulli&#39;s Principle, by changing the relative orientation of the outlet passageway/outlet opening and the channel through the housing to thus change the relative dimensions of the outlet opening  133  at the point of transition between the outlet passageway  132  and the passageway  107  through the housing  105 . This is illustrated best in  FIGS. 9 and 10 , which depict two of the possible relative orientations between an outlet passageway  132 /opening  133  of the inner member  130  and the passageway  107  through the housing  105 . According to the first position, shown in  FIG. 9 , the inner member  130  is oriented relative to the housing  105  so that the passageway  107  and the outlet passageway  132  are out of alignment, thereby forcing the fluid (not shown) through the constricted passage defined by the tapering dimensions of the outlet opening  133 . In the second position, shown in  FIG. 10 , the inner member  130  is oriented relative to the housing  105  so that the outlet passageway  132  and passageway  107  are aligned, thus maintaining a relatively constant fluid-communication passage from the inner member through the housing. Of course, it will be understood by those skilled in the art that the foregoing depict just two possible relative orientations, and that the foregoing in fact permits a myriad of relative orientations between the inner member and housing so as to provide considerable adjustability in the velocity of fluid flow from the inner member through the housing and thence to whatever downstream elements may be provided for fluid actuation.  
      It will also be understood from the foregoing that the outlet opening  133  may be varied from that depicted in the above-described embodiment in order to tailor the variability of the flow rate as desired for a given application. Such variation in the configuration of the outlet openings may be in the two-dimensional and/or three-dimensional shape thereof. Thus, for instance, the length of the opening  133  may be extended to provide even greater variability in the rate of fluid flow between the inner member and the housing. Likewise, it will be understood that the variable-flow outlet openings as herein described may, in the alternative, be defined in the housing proximate the inlet to the outlet passageway therethrough, thereby essentially reversing the configuration of the illustrated embodiments. Finally, it will be understood that the variable-flow outlet openings as herein described may be defined in both the inner member and the housing to vary even more precisely the rate of fluid flow from the inner member to the housing. For instance, it is contemplated that in such an alternative construction the variable-flow outlet openings such as described herein would be defined in the housing and oriented so as to constitute mirror-images of the variable-flow outlet openings defined in the inner member.  
      As depicted in  FIG. 11 , these variable-flow outlet openings  133  (and the associated passageways  132 ) may be arranged on the inner member  130  helically, as shown in the other embodiments of the invention heretofore described. Of course, the arrangements of the outlet openings and their associated outlet passageways shown and described is not meant to be limiting of the present invention. Those skilled in the art, having the benefit if this disclosure, will appreciate that multiple such arrangements are possible, according to the valve operations desired, without departing from the broader aspects of this invention.  
      It is also contemplated that the inventive valve may be designed so as to selectively bring into communication multiple sets of passageways in the interior member and the housing simultaneously. One such arrangement is shown in the alternative embodiment of  FIG. 12 , according to which the inner member  230  is provided with at least one pair of outlet openings  233   a ,  233   b  aligned along the longitudinal axis of the inner member  230 , each such outlet opening having a corresponding passageway through the housing with which it may be selectively brought into alignment. As depicted, these outlet openings are of both the constant  233   a  and variable  233   b  embodiments described hereinabove, although it will be understood that any combination of such outlet openings may be provided. By this configuration, it will be understood that the inner member is capable of providing for the simultaneous porting of fluid through at least the two outlet openings as shown.  
      Also according to this invention, the inner member may elastically expandable radially outwardly under the pressure of a fluid contained in the inner member interior cavity so as to bring at least the one or more raised projections and associated outlet openings of the inner member into sealing contact with the interior surface of the housing wall under operating conditions. Without limitation, such elastic expandability may be imparted by fabricating at least the cylindrical wall of the inner member from a suitably elastic material such as, for example, a polymer, including, without limitation, polyamide, polyester, polyacetal, etc. It will be appreciated that metals and other materials may also be substituted for the foregoing exemplary polymers, subject only to the requirement that such alternative materials be characterized, through one or both of inherent material characteristics and construction, by sufficient elastic expandability as previously mentioned. The balance of the inner member, including the second inner member portion, may be fabricated from the same or another material, but is preferably characterized by a rigid construction relative to the cylindrical wall.  
      Referring specifically to  FIG. 4 , there is depicted a detailed view of the valve of the present invention wherein the interior cavity  31  of the inner member  30  is shown filled with a hydraulic fluid supplied through the housing  5  and inner member  30  from an external source (not illustrated), which fluid creates an internal pressure sufficient to urge the cylindrical wall  40  radially outwardly to bring the raised projection  50  into engagement with the interior surface of the housing  5  cylindrical wall  10 .  
      As will be understood by those skilled in the art having the benefit of this disclosure, the acceptable frictional engagement between the raised projections  50  and the interior surface of the housing  5  cylindrical wall  10  will depend upon a number of factors, including the hydraulic fluid employed, the pressure created by the fluid within the inner member  30 , the relative elasticity of the material employed in fabricating at least the cylindrical wall  40  of the inner member  30 , and the size of the inner member  30 .  
      Preferably, though not absolutely, the inventive valve is provided with means for reducing frictional engagement between the interior surface of the housing cylindrical wall and the one or more raised projections of the inner member under operating conditions—i.e., under conditions when cylindrical wall of the inner member is expanded radially outwardly by the pressure of a fluid contained within the interior space. According to one embodiment, such friction-reducing means comprise the provision of a fluid suspension in the circumferential space between the inner member  30  and housing  5 . Such fluid-suspension may result from the purposeful design of the inner member  30  to create less than complete sealing engagement between the inner member  30  and the housing  5  under operating conditions, such that an amount of fluid just sufficient for lubricating the interior surface of the housing  5  cylindrical wall  10  and the outlet openings  32  of the inner member  30  is permitted to “leak” out from the outlet openings  32 . In this fashion, the outlet openings  32  would effectively self-lubricate the associated raised projections  50 .  
      According to a further embodiment, shown in  FIG. 13 , the first inner member portion  30   a ″′ may be provided with one or more additional passageways  53  formed through the cylindrical wall  40 ″′ thereof, each such passageway  53  communicating fluid from the interior space  31 ″′ to a lubrication channel  54  defined on the exterior surface of the cylindrical wall  40 ″′ by a pair of spaced apart, parallel annular beads or rims  55  extending circumferentially about the cylindrical wall&#39;s exterior surface. These annular beads  55  may be spaced so as to also regulate the sealing pressure between the outlet openings and the interior wall of the housing.  
      Referring now to  FIGS. 2, 4  and  14 , operation of the present invention in one exemplary environment—wherein the valve  1  hereof is coupled to the remainder of an automatic transmission system, including a controller  60  responsive to signals from any of a variety of conventional data inputs, including, for instance, the throttle, the governor, output shaft torque, vehicle speed, etc., and operative to effect actuation of the motor  65  and selectively rotate the inner member, an hydraulic fluid supply  70  for the shift valve  1 , and a manifold  80  communicating fluid from the shift valve  1  to activators for the clutches—will be better understood. More specifically, by operation of the motor  65  in response to the controller  60 , the inner member of the shift valve  1  is selectively rotatably moved relative to the outer housing of the valve  1  by an angular distance which brings a desired one of the outlet openings  32  and its associated outlet passageway  33  into radial alignment with one of the plurality of radial outlet passageways  7  defined through the housing  5 , thereby permitting communication of hydraulic fluid from the interior cavity  31  of the inner member  30  to the exterior of the housing  5  (and thence through an opening  81  in the manifold  80  to a selected one of the clutch activators) via the radially aligned passageways  7  and  33 .  
      It will be appreciated, with reference being had to the foregoing disclosure, that the present invention provides an automatic transmission in which the shift valve thereof is at once relatively small and lightweight, and which requires less stringent tolerances between the operating components thereof as compared to prior art shift valves.  
      Of course, the foregoing is merely illustrative of the present invention, and those of ordinary skill in the art will appreciate that many additions and modifications to the present invention, as set out in this disclosure, are possible without departing from the spirit and broader aspects of this invention as defined in the appended claims.