Abstract:
In transmissions having input clutches, a lever arm configured as a second class lever is pivoted at one end, applies force to a clutch bearing near its middle and is acted upon by a linear actuator at its opposite end. The present invention relates to mechanisms for adjusting the location of the pivot to compensate for clutch wear. The fixed pivot is replaced by a linear one way clutch mechanism. As the clutch facing wears and the clutch is activated, an extension of the actuating lever arm abuts a stationary stop beyond the one way clutch pivot which translates the pivot point provided by the one way clutch mechanism toward the clutch to reduce pre-travel and compensate for clutch facing wear. Hydraulic and spring biasing of the pivot point are also disclosed.

Description:
FIELD 
       [0001]    The present disclosure relates to adjustment mechanisms for clutches and more particularly to wear compensating adjustment mechanisms for motor vehicle clutches for single and dual clutch transmissions. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0003]    Motor vehicle transmissions are often divided into two distinct classes: manual transmissions and automatic transmissions. Manual transmissions typically have a plurality of operator selected gears and a manual (foot operated) clutch whereas automatic transmissions sequence gear selection and clutch operation, generally without active operator involvement. 
         [0004]    A recent addition to the transmission repertoire combines elements of both manual and automatic transmissions: the dual clutch transmission or DCT. The dual clutch transmission utilizes meshing pairs of gears and synchronizer clutches much like a manual transmission but with a pair of friction clutches. Because selection and engagement of gears and clutch are typically under the control of an electronic control system (a transmission control module or TCM), the dual clutch transmission essentially functions as an automatic transmission. 
         [0005]    The meshing gears are arranged in a dual clutch transmission such that alternating gears in an upshift (or downshift) sequence, e.g., first, third and fifth, are associated with one of the two clutches and the interleaved, alternating gears, e.g., second, fourth and sixth are associated with the other clutch. In this way, while one gear and clutch is engaged and operating, for example, second gear, the next higher gear in an upshift sequence, for example third, is being synchronized and connected to a driveshaft so that the actual shift from second to third involves essentially simply disengaging the one clutch and engaging the other clutch. 
         [0006]    This shift sequence of dual clutch transmissions provides very rapid adjacent gear upshifts and downshifts and is one of the most desirable and appreciated features of this transmission type. Shift times of about 200 milliseconds or less are achievable by such transmissions. 
         [0007]    In order to achieve such reduced shift sequence times, it is necessary that, among other considerations, clutch travel must be reduced to a minimum. It can readily be appreciated that excessive clutch pre-travel, i.e., travel of the clutch actuator and linkage from a released position to an applied position simply delays a desired clutch and transmission action. Moreover, as the clutch facing material wears, the pre-travel will increase, thus effectively further slowing the response time of the clutch. Accordingly, it is highly desirable to configure both a single and a dual clutch transmission clutch to reduce pre-travel and provide optimum clutch response time. The present invention is so directed. 
       SUMMARY 
       [0008]    The present invention provides adjustment mechanisms for motor vehicle clutches for single and dual clutch transmissions. In transmissions having one or two input clutches, a lever arm configured as a second class lever is pivoted at one end, applies force to a clutch bearing near its middle and is acted upon by a bi-directional linear actuator at its opposite end. The present invention relates to mechanisms for adjusting the location of the pivot to compensate for clutch wear. The fixed pivot is replaced by a linear one way clutch device. As the clutch facing wears and when the clutch is activated, an extension of the actuating lever arm abuts a stationary stop beyond the one way clutch pivot which repositions the pivot point toward the input clutch to reduce pre-travel and compensate for clutch wear. Hydraulic and spring biased adjustment of the one way clutch pivot are also disclosed. 
         [0009]    Thus it is an object of the present invention to provide an adjustment mechanism for a single clutch of a motor vehicle transmission. 
         [0010]    It is a further object of the present invention to provide an adjustment mechanism for both clutches of a dual clutch transmission for a motor vehicle. 
         [0011]    It is a still further object of the present invention to provide an adjustment mechanism for a clutch for a motor vehicle transmission having a moveable pivot. 
         [0012]    It is a still further object of the present invention to provide an adjustment mechanism for a clutch for a motor vehicle transmission having a pivot including a one way clutch. 
         [0013]    It is a still further object of the present invention to provide an adjustment mechanism for a clutch for a motor vehicle transmission having a an extension on the clutch lever arm and a stop adjacent the pivot. 
         [0014]    It is a still further object of the present invention to provide an adjustment mechanism for a clutch for a motor vehicle transmission having a one way clutch and hydraulic assembly. 
         [0015]    Further objects, advantages and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0016]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0017]      FIG. 1  is a full sectional view of a clutch for a dual clutch motor vehicle transmission incorporating the present invention; 
           [0018]      FIG. 2  is an enlarged, side elevational view of a clutch lever arm and adjustment mechanism according to the present invention; 
           [0019]      FIG. 3  is a greatly enlarged, sectional view of a portion of a clutch lever arm and adjustment mechanism according to the present invention; 
           [0020]      FIG. 4  is an enlarged, side elevational view of clutch lever arms and an adjustment mechanism having hydraulic biasing according to the present invention; and 
           [0021]      FIG. 5  is an enlarged, side elevational view of clutch lever arms and an adjustment mechanism having mechanical spring biasing according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0023]    With reference to  FIG. 1 , a dual main or input friction clutch for a dual clutch transmission is illustrated and generally designated by the reference number  10 . The dual input clutch  10  includes a stationary housing  12  which generally surrounds the active components of the clutch  10  such as an input shaft  16  which is coupled to and driven by a prime mover (not illustrated) such as a gasoline, Diesel, flex fuel or hybrid power plant. The input shaft  16  is coupled to a clutch drive housing  20  which, in turn, is coupled to and drives a clutch drive plate  22 . Spaced from both the front and rear surfaces are pressure plates: a first or front pressure plate  26  and a second or rear pressure plate  28 . Disposed between the front pressure plate  26  and the clutch drive plate  22  is a first selectively driven clutch output plate or disc  32  which includes friction material or facing  24  on both surfaces. The first clutch output disc  32  is connected through a first plurality of anti-chatter springs  34  to a first output annulus  36  which is secured to a first output collar  38 . The first output collar  38  is coupled by an interengaging spline set  42  to a first output shaft  44 . Preferably, the first output shaft  44  includes a first bearing assembly  46  proximate its forward terminus which is received within the input shaft  16 . Disposed between the rear pressure plate  28  and the clutch drive plate  22  is a second selectively driven clutch output plate or disc  52  which also includes friction material or facing  24  on both surfaces. The second clutch output disc  52  is connected through a second plurality of anti-chatter springs  54  to a second output annulus  56  which is secured to a second output collar  58 . The second output collar  58  is coupled by an interengaging spline set  62  to a second output quill or drive member  64 . Preferably, a second bearing assembly  66  is disposed between the second output quill or drive member  64  and the clutch drive plate  22 . 
         [0024]    A first axially moveable annular member  72  is coupled to and rotates with the first or front pressure plate  26  and extends to the rear of the clutch  10  where it is engaged by a first diaphragm spring  74 . The first diaphragm spring  74  is pivoted about the clutch cover plate  102  and the inner end is engaged by a first, larger diameter clutch bearing  76 . The clutch cover plate  102  is rigidly attached to the clutch drive plate  22 . The first clutch bearing  76  is piloted on the second quill or drive member  64  and is axially translated by a first self-adjusting clutch actuation assembly  80 . 
         [0025]    A second or rear pressure plate  28  extends to the rear of the clutch  10  where it is engaged by a second diaphragm spring  104 . The second diaphragm spring  104  is pivoted in the clutch drive housing  20  about the clutch cover plate  102  and its inner end is engaged by a second, smaller diameter clutch bearing  106 . The second clutch bearing  106  is also piloted on the second quill or drive member  64  and is axially translated by a second self-adjusting clutch actuation assembly  110 . 
         [0026]    The first self-adjusting clutch actuation assembly  80  includes a first lever arm  82  that functions as a second class lever: at a first, upper end, a hemi-spherical socket  84  receives a complementary hemi-spherical terminus  86  of a first hydraulic piston  88  that is received within a first cylinder  90 . The first piston  88  and the first cylinder  90  include appropriate seals  92  and a first input port  94  which receives pressurized hydraulic fluid which extends the first piston  88 , translates the first lever arm  82  and the first bearing  76  to the left in  FIG. 1 , thereby engaging the first pressure plate  26 . The second, lower end of the first lever arm  82  includes a hemi-spherical socket  96  and a through opening  98  which receives a reduced diameter portion  132 A of a shaft  132  of a self-adjusting assembly  130 . 
         [0027]    The second self-adjusting clutch actuation assembly  110  includes a second lever arm  112  that also functions as a second class lever and which includes a first, upper end having a hemi-spherical socket  114  which receives a complementary hemi-spherical terminus  116  of a second hydraulic piston  118  that is received within a second cylinder  120 . The second piston  118  and the second cylinder  120  include appropriate seals  122  and a second input port  124  which receives pressurized hydraulic fluid which extends the second piston  118 , translates the second lever arm  112  and the second bearing  106  to the left in  FIG. 1 , thereby engaging the second pressure plate  28 . The second, lower end of the second lever arm  112  also includes a hemi-spherical socket  126  and a through opening  128  which receives the reduced diameter portion  132 A of the shaft  132  of the self-adjusting assembly  130 . 
         [0028]    Referring now to  FIGS. 2 and 3 , it will be appreciated that only the first lever arm assembly  80  is illustrated because only the first lever arm  82  effects self adjustment of the clutches as will be described below. It should be understood, however, that the self-adjusting assembly  130  is connected to and adjusts both lever arms  82  and  102 , as illustrated in  FIG. 1 . The self-adjusting assembly  130  is essentially a linear one way clutch which functions as the pivot point of the first lever arm  82  and the second lever arm  102 . The self-adjusting linear one way clutch assembly  130  is mounted and secured within an opening  134  of the stationary housing  12 . The self-adjusting linear one way clutch assembly  130  includes a tubular or cylindrical housing  136  which receives an annular ramp member  138  having a frusto-conical inner surface  142  which engages a plurality of balls  144 . The balls  144 , in turn, engage the shaft  132 . An intermediate collar  146  resides between the shaft  132  and the housing  136  and includes a shoulder or flange  148 . The balls  144  are disposed on one side of the flange  148  and a compression spring  152  is disposed on the opposite side of the flange  148  and biases the balls  144  toward the annular ramp member  138  and the shaft  132 . The shaft  132  also includes a hemi-spherical surface  154  at the transition to the reduced diameter portion  132 A and friction reducing hemi-spherical washers  156 . A fastener  158  such as a push-on retainer or similar component retains the lever arms  82  and  102  on the reduced diameter portion  132 A of the shaft  132 . 
         [0029]    The first lever arm  82  includes an extension  162  which terminates proximate a boss, lug or stop  164  of the housing  12 . As illustrated in  FIGS. 1 ,  2  and  3 , as the clutch friction material or facing  24  wears and reduces in thickness, the upper portion of the first lever arm  82  will travel farther to the left to achieve the same clutch action when the facing  24  was thicker. Accordingly, the extension  162  on the first lever arm  82  will eventually contact the boss or stop  164 . When the first hydraulic piston  88  is activated and translated, the boss or stop  164  will act as a pivot point, drawing the shaft  132  out of the self-adjusting assembly  130  and resetting the pivot point to compensate for wear of the clutch facing  24  and reduce pre-travel of the clutch activation linkage. 
         [0030]    Two features should be noted and appreciated. First of all, it is apparent from the foregoing description that only wear of the first clutch effects self-adjustment. In a dual clutch transmission, the clutches are associated with alternate gears, e.g., a first clutch with first, third and fifth gears, a second clutch with reverse, second, fourth and sixth gears. Thus clutch wear tends to be quite uniform and sensing wear of one clutch and utilizing it as the basis to adjust both clutches has been found to be satisfactory. Second of all, it should be apparent that the single self-adjustment assembly  130  is thus wholly suited for use with a single clutch and single lever arm in a conventional manual transmission. 
         [0031]    Referring now to  FIG. 4 , a first alternate embodiment self-adjusting mechanism is illustrated and generally designated by the reference number  200 . Rather than incorporating the lever arm extension  162  and the lug or stop  164  (illustrated in  FIGS. 1 ,  2  and  3 ), the first alternate embodiment  200  incorporates a hydraulic self-adjuster. As such, the first alternate embodiment  200  includes the tubular housing  136 , the annular ramp member  138  having the frusto-conical inner surface  142  which engages the plurality of balls  144 , the intermediate collar  146  having the shoulder or flange  148  and the compression spring  152 . An elongate shaft  202  includes a reduced diameter portion  202 A which engages the lower ends of the lever arms  82  and  112  and an enlarged diameter portion or piston  204  having an O-ring seal  206  received therein. A fluid chamber  210  is provided with pressurized hydraulic fluid through a port  212 . In the first alternate embodiment  200 , sensors (not illustrated) sense or determine increased travel of the first and/or second lever arms  82  and  112  and a hydraulic controller (also not illustrated) supplies pressurized hydraulic fluid to the fluid chamber  210  to translate the piston  204  and the shaft  202  to reset the pivot point of the lever arms  82  and  112 . The annular ramp member  138  and the balls  144  again function as a linear one way clutch and maintain the position of the shaft  202  after it translates to compensate for clutch facing wear and reduce pre-travel. 
         [0032]    Referring now to  FIG. 5 , a second alternate embodiment self-adjusting mechanism is illustrated and generally designated by the reference number  220 . Rather than incorporating the lever arm extension  162  and the lug or stop  164  (illustrated in  FIGS. 1 ,  2  and  3 ) or the hydraulically assisted shaft  202  and piston  204  of the first alternate embodiment  200 , the second alternate embodiment  220  includes a passive biasing assembly. Accordingly, the second alternate embodiment  220  includes a shaft  132 ′ having the reduced diameter portion  132 A, the tubular housing  136 , the annular ramp member  138  having the frusto-conical inner surface  142  which engages the plurality of balls  144 , the intermediate collar  146  having the shoulder or flange  148  and the compression spring  152 . An opening  134 ′ in the housing  12  is somewhat larger that the opening  134  illustrated in  FIGS. 1 ,  2  and  3  and receives a plurality of springs washers  222  such as Belleville springs or wave washers. The spring washers  222  provide a passive biasing force to the shaft  132 ′ which assists translation and resetting of the pivot point of the lever arms  82  and  112  to adjust for clutch wear and reduce pre-travel. In order to assist assembly of the alternate embodiment  220 , a pin  224  may be disposed within a transverse bore  226  which extends through the collar  146  and the shaft  132 ′ to retain these components in the relative position illustrated in  FIG. 5  until they are assembled at which time the pin  224  may be removed. 
         [0033]    The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.