Abstract:
Several distinct motor vehicle clutch fork and release bearing lubrication arrangements which may be utilized singly or in various combinations include: oil impregnated inserts, self-lubricating pockets, single or multiple central grease fittings in communication with passageways that provide grease to contact and bearing surfaces and sealed boots filled with lubricant which cover a portion of ends of the release fork.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates generally to motor vehicle clutches of the manual type and more specifically to manual motor vehicle clutches having various arrangements for providing and improving lubrication of certain components.  
         [0002]     Both the location and operation of a manual motor vehicle clutch suggests the difficulty of its existence. A typical manual motor vehicle clutch is disposed behind the prime mover which is typically an internal combustion gas or Diesel engine and a head of the transmission. In service, it is called upon to repeatedly connect and disconnect the driving force of the engine to the transmission. Hundreds of horsepower, hundreds of foot pounds of torque, thousands of revolutions per minute and thousands of operating cycles characterize its operating environment.  
         [0003]     Sandwiched between the prime mover and transmission of a vehicle, replacing or even servicing a manual clutch is a project to reckon with. Due to the expense of replacing the clutch, which includes not only replacement components and labor but also the down time of the vehicle, it is not surprising that significant effort has been undertaken to improve and extend the service life of the clutch. This effort has taken many forms: the constant search for improved friction materials being only one.  
         [0004]     In a typical manual clutch, a release or throw out bearing is translated axially along the transmission input shaft by a release fork which may be coupled through a linkage to the clutch pedal or coupled through a closed hydraulic system to the clutch pedal. The release bearing removes the pressure applied to the clutch plate and thus controls engagement and disengagement of the clutch. Because the release bearing may rotate relative to the transmission input shaft and because substantial force is applied to the release biasing by the release fork, the interface between the two components as well as other release fork features such as its pivot should be consistently supplied with a lubricant such as grease. The present invention addresses this requirement.  
       SUMMARY OF THE INVENTION  
       [0005]     Several distinct motor vehicle clutch fork and release bearing lubrication arrangements which may be utilized singly or in various combinations include: oil impregnated inserts, self-lubricating pockets, single or multiple centrally disposed grease or zirc fittings in communication with passageways that provide grease to contact and bearing surfaces and flexible boots filled with lubricant which cover a portion of the ends of the release fork.  
         [0006]     Thus it is an object of the present invention to provide various means for ensuring the consistent presence of lubrication on motor vehicle clutch components.  
         [0007]     It is a further object of the present invention to provide lubrication to the release bearing and release fork of a manual clutch by incorporating oil impregnated inserts into the release bearing.  
         [0008]     It is a still further object of the present invention to provide lubrication to the release bearing and release fork of a manual clutch by incorporating grease retaining circumferential grooves into the release bearing.  
         [0009]     It is a still further object of the present invention to provide lubrication to the release fork and release bearing of a manual clutch by incorporating a lubricating arrangement including lubricant retaining grooves, passageways and a grease fitting in the release bearing.  
         [0010]     It is a still further object of the present invention to provide lubrication to the release bearing and release fork of a manual clutch by incorporating a central lubricating arrangement including zirc fittings and passageways in the release fork.  
         [0011]     It is a still further object of the present invention to provide lubrication to the release bearing and release fork of a manual clutch by incorporating lubricant boots on the ends of the release fork.  
         [0012]     Further objects and advantages of the present invention will become apparent by reference to the following description of the preferred embodiment and appended drawings wherein like reference numbers refer to the same component, element or feature. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a side elevational view in full section of a typical manually actuated motor vehicle friction clutch;  
         [0014]      FIG. 2  is an enlarged, fragmentary, sectional view of a release bearing including lubricating inserts according to the present invention;  
         [0015]      FIG. 3  is an enlarged, fragmentary, sectional view of a manual clutch release bearing and fork having lubricating grooves according to the present invention;  
         [0016]      FIG. 4  is an enlarged, fragmentary, sectional view of a manual clutch release bearing and fork having lubricating grooves, lubricant passageways and grease fittings according to the present invention;  
         [0017]      FIG. 5  is a fragmentary, perspective view of a release bearing and release fork of a manual clutch having zirc fittings and lubricant passageways according to the present invention;  
         [0018]      FIG. 6  is a fragmentary, perspective view of a release bearing and release fork of a manual clutch having a zirc fitting and lubricant passageways according to the present invention; and  
         [0019]      FIG. 7  is a fragmentary, perspective view of a release bearing and release fork of a manual clutch incorporating a lubricant boot according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]     Referring now to  FIG. 1 , a typical, manual motor vehicle clutch, representative of many configurations and variations, is illustrated and designated by the reference number  10 . The motor vehicle clutch  10  includes a circular clutch or support plate  20  having inner and outer linings and surfaces of friction material  22 . The clutch plate  20  is rotationally coupled to an inner hub  24  through a plurality of torsional spring dampers  26  disposed in conventional circumferential fashion. The inner hub  24  is coupled by interengaging sets of male and female splines  28  to a transmission input shaft  30 . The clutch plate  20  is disposed between a fly wheel (not illustrated) driven by a prime mover such as an internal combustion gasoline or Diesel engine and an annular pressure plate  34 . The pressure plate  34  is acted upon by an annular diaphragm spring  36  which functions as a second class lever to transmit axial force to the pressure plate  34  and cause axial translation thereof upon axial translation of a clutch release bearing assembly  40 . The clutch release bearing assembly  40  generally includes a circular collar  42  which engages the diaphragm spring  36 , a return spring  44  which biases the clutch release bearing assembly  40  to the left as illustrated in  FIG. 1 , a pair of bearing assemblies  46  and  48  including a thrust bearing assembly  46  and ball bearing assembly  48  which reduce friction and allow free rotation of the clutch collar  42  relative to a release hub or bearing  50  defining a circumferential channel  52 .  
         [0021]     In turn, the circumferential channel  52  of the release hub bearing  50  is engaged by the spaced apart arms or terminal portions  58  of a release fork  60 . The release fork  60  is pivotally disposed upon a transverse pivot pin  62  and functions as a first class lever. As such, the release fork  60  is acted upon by an end portion of a clutch linkage  64  which translates to the left and right, as illustrated in  FIG. 1 , to disengage and engage the clutch  10 , respectively. It will be appreciated that the foregoing description of the clutch  10  is representative and exemplary only and is intended to generally present the components of a typical manual motor vehicle clutch and the environment within which the present invention resides.  
         [0022]     Referring now to  FIG. 2 , a first embodiment lubrication arrangement for the manual clutch release bearing  50  is illustrated. As noted, the release bearing  50  includes a circumferential groove or channel  52  which receives a pair of spaced apart shift arms  58  of the release fork  60 , one of which is illustrated in  FIG. 2 . Disposed within the circumferential channel  52  of the release bearing  50  is a first cylindrical oil or grease impregnated bronze insert  72  and a second annular oil impregnated bronze insert  74  disposed at a right angle to the first oil or grease impregnated insert  72 . Together, the oil or grease impregnated bronze inserts  72  and  74  fully cover the surfaces of the release hub or bearing  50  against which the release arms  58  engage. Hence, friction is reduced relative to non-oil impregnated components and the service life of both the release arms  58  and the release hub or bearing  50  are improved. The oil or grease impregnated bronze inserts  72  and  74  may be of any porous lubrication bearing structure or microstructure such as sintered metal. The oil or grease impregnated inserts  72  and  74  may be cast in place on the release bearing  50  or both may consist of two or more cylindrical or curved sections. The annular insert  74  may be configured with oblique inner edges  76  which engage complementarily configured oblique edges  78  on the cylindrical insert  72  to retain them. In turn, the annular inserts  74  are retained in the release bearing  50  by a plurality of threaded fasteners  82  which extend through the release bearing wall and into the insert  74 .  
         [0023]     Referring now to  FIG. 3 , a second motor vehicle manual clutch lubrication arrangement for a release bearing  50 ′ is illustrated and designated by the reference number  90 . Here, a plurality of circumferential grooves  92 , two of which are disposed at the bottom of the circumferential groove  52  and a third groove  94  is disposed along the sidewall are filled with a heavy grease  96 . The grease  96  is thus disposed exactly at the regions of contact between the release arms  58  and the release bearing  50 ′. In fact, as the release bearing  50 ′ slowly wears, such wearing will involve exposure of additional lubricant or grease  96  and thus its distribution about the circumferential groove  52 .  
         [0024]     Referring now to  FIG. 4 , a third motor vehicle clutch lubrication arrangement for a release bearing  50 ″ is illustrated and designated by the reference number  100 . Here, a plurality of circumferential grooves  102  are formed in the friction services of the release bearing  50 ″ and are in communication with one or more internal passageways  104  which terminate and communication with grease or zirc fittings  106 . Although two zirc fittings  106  are illustrated, it will be appreciated that a single zirc fitting  106  and single passageway  104  may be utilized to provide grease  108  to all of the circumferential grooves  102 .  
         [0025]     Referring now to  FIG. 5 , a fourth embodiment of a manual clutch release bearing lubrication arrangement is illustrated and designated by the reference number  110 . Here, a pair of zirc fittings  112  each disposed proximate the end of the release fork  58 , one of which is illustrated in  FIG. 5 , communicate with a passageway  114  which receives, stores and distributes grease  116  to the contacting and frictional features of the arms  58  of the release fork  60  and the release bearing  50 . Similarly, a grease or zirc fitting  118  disposed in a central portion of the release fork  60  communicates through a passageway  122  with the release fork pivot pin  62  and provides a lubricant such as grease  124  into this region to reduce friction and improve the service life of these components.  
         [0026]     Referring now to  FIG. 6 , a fifth embodiment manual clutch release bearing lubrication arrangement is illustrated and designated by the reference number  130 . Here, a single grease or zirc fitting  132  communicates with a plurality of passageways, a first passageway  134  communicating and providing a lubricant such as grease to the pivot pin  62  and a second pair of diverging passageways  136 A and  136 B which carry the lubricant to each terminal portion of the release forks  58  and provides such lubricant to the points of contact to reduce sliding friction and improve the service life of the components.  
         [0027]     Finally, referring to  FIG. 7 , a sixth embodiment of a manual clutch release bearing lubrication arrangement is illustrated and designated by the reference number  140 . Here, in addition to the grease or zirc fitting  132  and the passageways  134 ,  136 A and  136 B, a flexible, preferably elastomeric boot  142  is utilized over the end of each of the release arms  58  to ensure retention of the lubricant such as grease and its application to the points of contact on the friction between the release arms  58  and the release bearing  50 . It will be appreciated that the composition of the flexible boot  142  be of a material such as a lubricant resistant elastomer which is compatible with and not degraded by the lubricant(s) utilized with the release fork  60  and release bearing  50 .  
         [0028]     It should be appreciated and understood that the various embodiments disclosed above may be utilized in various combinations on a release fork and bearing assembly. For example, the oil impregnated inserts  72  and  74  may be utilized with a release fork  60  having a flexible boot  142 . Or, the inserts  72  and  74  may be utilized with the centralized lubrication arrangement  130  illustrated in  FIG. 6 .  
         [0029]     The foregoing disclosure is the best mode devised by the inventor for practicing this invention. It is apparent, however, that methods incorporating modifications and variations will be obvious to one skilled in the art of motor vehicle clutches and lubrication thereof. Inasmuch as the foregoing disclosure is intended to enable one skilled in the pertinent art to practice the instant invention, it should not be construed to be limited thereby but should be construed to include such aforementioned obvious variations and be limited only by the spirit and scope of the following claims.