Abstract:
A transmission clutch module includes first and second races, and a plurality of race engagement mechanisms situated between the races. The module incorporates an integrated hydraulic actuator having an actuator cam ring that includes cam ramps configured for moving the race engagement mechanisms between positions adapted to selectively interact with the races. As such, the actuator, designed to be contained entirely within a generally circumferential envelope of the clutch module, may control rotation of the actuator cam ring between at least two spaced angular positions in at least one embodiment. In various other embodiments within the scope of this disclosure, the actuator cam ring may be adapted to rotate among any number of pre-determined positions to operatively permit or prevent the transmittal of torque between the first and second races.

Description:
FIELD OF DISCLOSURE 
       [0001]    The present disclosure relates generally to overrunning clutches for automatic transmissions, and more particularly to multiple mode clutch actuators employed in the operation of such clutches. 
       BACKGROUND OF DISCLOSURE 
       [0002]    Although the present disclosure has applicability beyond automotive, an automotive example and discussion is herein provided for context only, and to specifically demonstrate at least one potential area of its utility. 
         [0003]    Accordingly, an automotive vehicle includes an internal combustion engine containing a rotary crankshaft configured to transfer motive power from the engine through a driveshaft to turn the wheels. A transmission is typically interposed between engine and driveshaft components to selectively control torque and speed ratios between the crankshaft and driveshaft. In a manually operated transmission, a corresponding manually operated clutch may be interposed between the engine and transmission to selectively engage and disengage the crankshaft from the driveshaft to facilitate manual shifting among available transmission gear ratios. 
         [0004]    On the other hand, if the transmission is automatic, the transmission will normally include an internal plurality of automatically actuated clutches adapted to dynamically shift among variously available gear ratios without requiring driver intervention. Pluralities of the clutches, also called clutch modules, are incorporated within such transmissions to facilitate the automatic gear ratio changes. 
         [0005]    In an automatic transmission of an automobile, multiple gear ratios are generally available, not including a reverse gear. The various gears may be structurally comprised of inner gears, intermediate gears such as planet or pinion gears supported by carriers, and outer ring gears. Specific transmission clutch modules may be associated with specific sets of the selectable gears within the transmission to facilitate the desired ratio changes. 
         [0006]    For example, one of the clutch modules of an automatic transmission associated with first (low) and reverse gear ratios may be normally situated at the front of the transmission and closely adjacent the engine crankshaft. The clutch may have an inner race and an outer race disposed circumferentially about the inner race. One of the races, for example the inner race, may be drivingly rotatable in only one direction. The inner race may be selectively locked to the outer race via an engagement mechanism such as, but not limited to, a roller, a sprag, or a pawl, as examples. In the one direction, the inner race may be effective to directly transfer rotational motion from the engine to the driveline. 
         [0007]    Within the latter system, the outer race may be fixed to an internal case or housing of an associated planetary member of the automatic transmission. Under such circumstances, in a first configuration the inner race may need to be adapted to drive in one rotational direction, but freewheel in the opposite direction, in a condition referred to as overrunning. Those skilled in the art will appreciate that overrunning may be particularly desirable under certain operating states, as for example when a vehicle is traveling downhill. Under such circumstance, a driveline may occasionally have a tendency to rotate faster than its associated engine crankshaft. Providing for the inner race to overrun the outer race may act to reduce drag and/or spin losses, for example. 
         [0008]    In a second configuration, such as when a vehicle may be in reverse gear, the engagement mechanisms may be adapted for actively engaging in both rotational directions of the inner race, thus not allowing for the overrunning condition in the non-driving direction. 
         [0009]    In yet other configurations, a clutch module may switch between modes adapted to be locked in another direction of rotation in a third mode, and to freewheel in both directions of rotation in an alternate, or fourth, mode. 
         [0010]    A significant issue has been related to actuators designed and adapted to switch clutch modules between their operative modes. Most such actuators have been bulky add-on, or adjunct, apparatus adapted to interact with the clutch module from outside of a generally circumferential envelope of the module, per se. As industry pressures have increasingly mandated reductions in footprints and/or sizes of automotive parts, improved actuators having such reduced footprints are needed. 
       SUMMARY OF DISCLOSURE 
       [0011]    In accordance with one aspect of the disclosure, an integrated actuator for a multi-mode clutch module may be adapted for use in an automatic transmission. The actuator mechanism, as defined herein, is entirely contained within the generally circumferential envelope of the multi-mode clutch module. In one disclosed embodiment, the clutch module comprises an inner race; a fixed outer race disposed concentrically about the inner race, and a plurality of engagement mechanisms, such as pawls, circumferentially disposed between the inner and outer races. A cam ring is adapted to rotate or “clock” between two operating modes via the integrated actuator. 
         [0012]    In one disclosed embodiment the cam ring interfaces with the engagement mechanisms to provide a first locked actuator mode, wherein inner race may be locked to the outer race in both driving and non-driving rotational directions. Conversely, a second actuator mode unlocks the inner and outer races to create a freewheeling of the races with respect to one another in both driving and non-driving rotational directions in that same embodiment. 
         [0013]    In accordance with another aspect, the multi-mode clutch module includes an actuator hydraulically adapted to bi-directionally clock between hard stops at two circumferential positions, one position locking the inner and outer races together in at least one of its rotational directions, and a second mode allowing the inner and outer races to freewheel with respect to each other in both directions. 
         [0014]    In accordance with another aspect, the multi-mode clutch module is configured to incorporate an actuator hub adapted to reactively engage the cam ring for circumferential movement against a spring force about the actuator hub. 
         [0015]    In yet another aspect, the integrated actuator includes a system of circumferentially disposed seals seated within respective engaging actuator hub and cam ring members. 
         [0016]    These and other aspects and features of the present disclosure may be better appreciated by reference to the following detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0017]      FIG. 1  is a perspective side view of a first embodiment of a clutch module that includes an integrated actuator constructed in accordance with the present disclosure, the clutch module shown without side plates to better reveal component details. 
           [0018]      FIG. 2  is a perspective cross-sectional view of the same clutch module, taken along lines  2 - 2  of  FIG. 1 . 
           [0019]      FIG. 3  is a side view of a second embodiment of a clutch module and actuator, also constructed in accordance with the present disclosure. 
           [0020]      FIG. 3A  is an enlarged view of a circled inset portion of the side view of  FIG. 3 . 
           [0021]      FIG. 4  perspective cross-sectional view of the second embodiment of the clutch module, taken along lines  4 - 4  of  FIG. 3 . 
           [0022]      FIG. 5  is an enlarged perspective side view of a specific component of the embodiment of the clutch module of  FIG. 5 . 
       
    
    
       [0023]    It should be understood that the drawings are not to scale, and that the disclosed embodiments are illustrated only diagrammatically and in partial views. It should also be understood that this disclosure is not limited to the particular embodiments illustrated herein. 
       DETAILED DESCRIPTION 
       [0024]    Referring initially to  FIGS. 1 and 2 , a multi-mode clutch module  10  may be utilized as a sub-unit of an automatic transmission (not shown). Such transmission may be employed in a front-wheel driven automobile, as only one example. The clutch module  10 , having an axis A-A, may be employed as a part of a clutch suitable for use with a forward gearset, and may include an annular outer race  12  splined to a transmission component, not shown. For this purpose, the outside diameter  14  of the annular outer race  12  may contain splines  16  as shown to mate with and engage mating splines (not shown) of an input element of the transmission in this first described embodiment. 
         [0025]    The interior diameter  18  of the annular outer race  12  incorporates a plurality of slots  20  in an array of evenly distributed spaces defined between teeth  22  that extend about the interior diameter  18 . An interiorly situated annular cam ring  24  is positioned radially inwardly of the outer race  12 ; the outer diameter  25  of the cam ring  24  contains ramps  26  adapted to indirectly interface with the slots  20  and teeth  22  of the outer race  12 , as will be further described herein. 
         [0026]    In the first described embodiment, the cam ring  24  includes a pair of radially inwardly extending hydraulic bosses  28  adapted to actuate shifts between modes of the multi-mode clutch module  10 . For this purpose, the cam ring  24  is adapted to bi-directionally rotate about axis A-A so as to “clock” between two limited angularly spaced stops. 
         [0027]    Situated intermediately between the outer race  12  and the cam ring  24  are a plurality of engagement mechanisms, shown herein as pawls  30 . The pawls  30  are adapted for selective interaction with the slots  20  and teeth  22  of the outer race  12  and the ramps  26  of the cam ring  24 . For this purpose, the pawls  30  are arranged in sets of pairs as shown, wherein the pawls  30 A are adapted, at least when interacting with teeth  22 , to facilitate the transfer of torque in one direction, and pawls  30 B are adapted to facilitate the transfer of torque in an opposite direction, as will be further explained below. 
         [0028]    For purposes of accommodating pawl rotation, each pawl  30  contains a pair of axially projecting arms  32  ( FIG. 2 ), each of the arms axially extending into a pair of left and right side plates  42  and  44 , respectively. In fact, it will be appreciated that the side plates  42 ,  44  effectively encapsulate the multi-mode clutch module components, including the pawls  30 , the cam ring  24 , and other components to be described. In addition, it will be noted that the side plates  42 ,  44  may be piloted within a pair of axially spaced, circumferentially extending, slots  17 ,  19  situated in the interior diameter  18  of the outer race  12  to facilitate relative rotation of the side plates with respect to the outer race  12 , or vice versa. Notably, the side plates  42 ,  44  are rigidly secured together by rivets  48  to a hub  50 , described below. Thus, the side plates and all of the above-noted components contained within the side plates may be non-rotatable relative to the rotatable outer race  12 , for example, as will be appreciated by those skilled in the art. 
         [0029]    Referring now particularly to  FIG. 1 , each of the pawls  30  incorporates an outwardly biased toe end  34  adapted to interact with slots  20  and teeth  22  of the annular outer race  12 . Each of the pawls also contains a heel end  36  adapted to interact with a ramp  26  of the cam ring  24 . Interacting with each pawl  30  for this purpose is a cantilevered leaf-style spring  38  extending from a spring apparatus  40 , the latter being fixedly secured to at least one of the side plates  42 ,  44 . Each leaf spring  38  is adapted to interact with one heel end  36  of one pawl  30 , as shown. 
         [0030]    Situated radially inwardly of the cam ring  24 , is an annular actuator hub  50 . Within the above-described multi-mode clutch module  10 , the hub  50  may be permanently splined to a transmission input shaft  60  in the first described embodiment, as shown. A radially outwardly extending hydraulic stop  52  of the hub  50  is adapted to interface with, and to limit amount of clocking of, the earlier noted hydraulic boss  28  of the cam ring  24 . For this purpose, an interior diameter portion  54  of the cam ring  24  is piloted for limited rotation on an outside diameter portion  56  of the radially extending hydraulic stop  52 . Hydraulic seals  58  are provided to seal between the cam ring  24  and the actuator hub  50 , as will be further explained below. 
         [0031]    For accommodating its interaction with the transmission input shaft  60 , the hub  50  includes a splined interior diameter  62 . The input shaft  60  interfaces with a source (not shown) of pressurized hydraulic fluid which travels through a fluid aperture  64  as can be viewed in the cutaway of the input shaft  60  in  FIG. 1 . The actuator hub  50  incorporates two radially oriented fluid passageways  70  for dynamically creating fluid pockets  72  that are controllably expansible and collapsible. Thus, when valves (not shown) adapted to control hydraulic fluid pressure are opened, the fluid flows radially outwardly of the input shaft  60 , through the passageways  70 , to create and expand hydraulic fluid pockets  72 . Conversely when the valves are closed, the fluid flows radially inwardly out of the pockets  72  to cause the pockets to collapse. 
         [0032]    A return spring  80  is circumferentially situated between each respective hydraulic boss  28  of the cam ring  24  and hydraulic stop  52  of the actuator hub  50 . The return spring  80  is adapted to cause the fluid to be forced out of the pockets  72  whenever the hydraulic fluid valves have been closed. Thus, those skilled in the art will appreciate that the hydraulic actuator function described herein is essentially a single-acting hydraulic actuation with a spring return. Such single-acting system may be used, for example, to assure that the actuator ring  24  moves to a desired default position upon a failure of the hydraulic fluid pressure system, thus causing the multi-mode clutch module  10  to go into a preferred default mode for safety purposes, as just one example. 
         [0033]    The scope of this disclosure is, however, not limited to such spring return, single-acting hydraulic actuation system. For example, a double-acting hydraulic actuation system (not shown) could be employed, which would not require the return spring  80 . 
         [0034]    The side plates  42 ,  44  play a fundamental role in controlling the torque path through the multi-mode clutch module  10 . As mentioned earlier, the pawls  30  have axial pivot arms  32  that extend into the apertures of the side plates  42 ,  44 . As such, whenever the pawls interact with the teeth  22 , those skilled in the art will appreciate that the torque path will flow directly from the input shaft  60  into the actuator hub  50 , then through the rivets  48  into the side plates  42 ,  44 . From the side plates, the torque path will flow through the pivot arms  32  of the pawls  30  into the toe ends  34  of the pawls, and hence into the outer race  12  via the teeth  22 . 
         [0035]    In addition to a passive role in torque path control, the tolerances of the side plates  42 ,  44  may be crucial for the overall functioning of the integrated actuator, depending on the application. Clearance tolerances between the cam ring  24  and the side plates may need to be controlled so that binding is avoided. On the other hand, excess leakage may also need to be avoided. In some cases, the tolerances may necessarily accommodate controlled leakage, particularly in applications where actuator duty cycles may be low. For applications requiring minimal leakage, polymer seals can be incorporated along axial faces of the side plates, as will be appreciated by those skilled in the art. 
         [0036]    Referring now to  FIGS. 3 and 4 , an alternate embodiment of a multi-mode clutch module  10 ′ may incorporate inverted and/or otherwise opposite characteristics relative to the first embodiment described in  FIG. 1 . For example, the inner race  50 ′ may be adapted to engage a ring gear of a planetary gearset (neither shown) to accommodate a reverse gearset clutch function, as opposed to forward gearset clutch function described with respect to the first embodiment as shown in  FIGS. 1 and 2 . Thus, the inner race  50 ′ includes radially outer (rather than inner) slots  20 ′ and teeth  22 ′ adapted to interact with a modified cam actuator ring  24 ′ via pawls  30 ′. 
         [0037]    The pawls  30 ′ interact inversely with respect to their described functions of the first embodiment, and the spring apparatus  40 ′ associated with respective sets of pawls are reversely positioned to achieve inverse functions as required in the second embodiment of the multi-mode clutch module  10 ′. 
         [0038]    In the embodiment of  FIGS. 3 and 4 , the outer race  12 ′ of the reverse clutch module  10 ′ does not rotate, but is rotatably fixed within a transmission housing (not shown).  FIG. 4  depicts side plates  42 ′ and  44 ′ that are analogous to the side plates  42  and  44  of the forward clutch module  10  ( FIG. 2 ). A total of five rivets  48 ′ secure the side plates  42 ′,  44 ′ together, analogously to the four rivets  48  adapted to secure the side plates  42 ,  44  of the first embodiment. 
         [0039]    The reverse clutch module  10 ′ contains only a single hydraulic actuator return spring  80 ′, in lieu of the two return springs  80  of the forward clutch module  10  ( FIG. 1 ). Similar to the embodiment of the clutch module  10 , a double acting hydraulic actuator may alternatively be incorporated in the clutch module  10 ′ for the same reasons provided earlier with respect to the clutch module  10 . Each of the clutch modules  10 ,  10 ′ may obviously be modified as necessary to meet the requirements of any given module design. 
         [0040]    Finally, those skilled in the art will appreciate that the clutch module  10  may be physically nested within the clutch module  10 ′ and used in conjunction with a planetary gearset to provide both forward and reverse functions for an automatic transmission (not shown) to, for example, accommodate a specific minimal sizing/packaging requirement. 
         [0041]    Referring now to  FIG. 3A , it will be apparent that the source of fluid required to form expansible and collapsible pockets  72 ′ are inversely situated relatively to those of pockets  72 , and must pass through the fluid passageway  70 ′ of the outer race  12 ′. For this to occur, the fluid source must emanate from the transmission casing (not shown) to which the outer race  12 ′ is splined. 
         [0042]    Also within the second described embodiment, the hydraulic stop  52 ′ is situated on the outer race  12 ′ rather than on the inner race, i.e. the actuator hub  50 , as in the first embodiment. Moreover, the hydraulic boss  28 ′ is situated on a radially outer portion  54 ′ of the cam ring  24 ′ rather than on the radially inner portion  54  of the cam ring  24  as in the first embodiment. 
         [0043]    Continuing reference to  FIG. 3A , a pair of mating faces  90 ,  92  of the hydraulic boss  28 ′ and hydraulic stop  52 ′, respectively, cooperate with the fluid passageways  70 ′ in a manner such that pressurized hydraulic fluid passing through the passageway  70 ′ will force the mating faces  90 ,  92  circumferentially apart against the force of the spring  80 ′ to thereby create a pocket  72 ′. 
         [0044]    Referring now to  FIG. 5 , in order to assure leak-proof operation for handling hydraulic fluid flows, a set of spring-loaded hydraulic seals  58 ,  58 ′ are utilized in both of the described first and second embodiments. For this purpose, recesses  82 ′,  84 ′ are provided in the boss  28 ′ and stop  52 ′, respectively, as shown. Each hydraulic seal  58 ′ ( FIG. 3A ) is individually formed as both a spring  94  and a sealing insert  96  formed in the nature of a vane seal, as shown in  FIG. 5 . 
         [0045]    The spring  94  may be formed in several practical configurations; a bowed leaf style, as depicted in  FIG. 5 , formed of spring steel, represents only one. The spring  94  is particularly essential for maintaining the sealing insert  96  in position while the hydraulic fluid is not under pressure. In the disclosed embodiment, the sealing insert  96  is defined by a pair of parallel ends or walls  95 ,  97  designed to capture respective ends of the bowed spring  94 . In the described embodiment, the insert walls  95 ,  97  are situated orthogonally to the actual sealing face  98  of the sealing insert, as shown. The seal insert  96  may be formed of a variety of materials, including but not limited to sintered metal, plastics, and/or ceramics. 
         [0046]    In operation, referring back to  FIG. 3A , when pressurized hydraulic fluid flows into the passageway  70 ′, the existing pocket  72 ′ will collapse as a new pocket  72 ′ will be formed between the faces  90  and  92 , as earlier described. A space  100  situated radially behind the sealing insert  96  is provided by the bowed spring  94 . Hydraulic fluid will flow into the space  100  to assure that sealing of the sealing insert  96  is actually effective. Without provision of such space  100 , the hydraulic fluid could otherwise force the insert against a side edge of the recess  82 ,  84  within respective hydraulic boss  28 ′ or hydraulic stop  52 ′, as those skilled in the art will appreciate. 
         [0047]    The structures herein described may have alternative configurations, even though not shown. The integrated actuator function of this disclosure could, for example, be configured to operate electrically instead of hydraulically. In addition, a biasing system involving a structure other than the accordion-style spring shown and described could be employed as a return. Although these modifications constitute only two examples, numerous other examples are applicable within the context of this disclosure. 
         [0048]    Finally, in accordance with the above-described embodiments, at least some of the following elements may collectively constitute the herein defined integrated actuator  46 ,  46 ′ of  FIGS. 1 and 3 , respectively, of this disclosure: 
         [0049]    a) cam rings  24 ,  24 ′ 
         [0050]    b) cam ramps  26 ,  26 ′ 
         [0051]    c) hydraulic bosses  28 ,  28 ′ 
         [0052]    d) hydraulic boss face  90 ,  90 ′ 
         [0053]    e) hydraulic stops  52 ,  52 ′ 
         [0054]    f) hydraulic stop face  92 ,  92 ′ 
         [0055]    g) oil passageways  70 ,  70 ′ 
         [0056]    h) hydraulic return spring  80 ,  80 ′ 
         [0057]    i) side plates  42 ,  42 ′,  44 ,  44 ′ 
         [0058]    j) actuator hub  50  (first embodiment) 
         [0059]    k) outer race  12 ′ (second embodiment) 
       INDUSTRIAL APPLICABILITY 
       [0060]    A clutch module including the integrated actuator of this disclosure may be employed in a variety of vehicular applications, including but not limited to, automobiles, trucks, off-road vehicles, and other machines of the type having engines, automatic transmissions, and drivelines. 
         [0061]    The disclosed actuator offers a unique approach to significantly reducing the size envelope and/or packaging of a clutch module of an automatic transmission. Such a benefit may be significant both in automotive transmissions and in numerous other applications where content density must be minimized, and/or packaging space is at a premium. 
         [0062]    Although the disclosed actuator has been described in only two embodiments/configurations, numerous additional embodiments/configurations may fall within the scope of the appended claims. 
         [0063]    For example, those skilled in the art will appreciate that the following configurations can be produced utilizing one of the above disclosed embodiments of either  FIGS. 1 and 3 :
   a) A 2-mode device having a single cam ring, wherein the hydraulic actuator is single acting with a spring return;   b) A 2-mode device having a single cam ring with a double acting actuator;   c) A 3-mode device having a single cam with a single acting actuator with a spring return, wherein the position of the cam ring is measured with an electronic sensor, and a variable solenoid is used to modulate hydraulic fluid to control cam ring position; and   d) A 3-mode device with a single cam with a double acting actuator (position of cam being measured with sensor, and cam ring position controlled by a variable solenoid that modulates hydraulic fluid).   e) A 4-mode device utilizing a single cam with single acting actuator having a spring return (cam position measured via sensor, with variable solenoid being used to modulate hydraulic fluid to control cam ring position;   f) A 4-mode device with single cam and double acting actuator (position of cam being measured with sensor, with variable solenoid used to modulate fluid to control cam position; and   g) A 4-mode device with two cams, each controlled with its own actuator, and each actuator being either single acting with a spring return, or double acting without requiring a spring.