Patent Document

TECHNICAL FIELD 
     The disclosure relates generally to articulated joints, and more specifically to a system and method for limiting the angular deflection of an articulated joint. 
     BACKGROUND ART 
     Constant velocity joints (CVJs) and other rotational joints are common components in automotive vehicles. Typically, constant velocity joints are used where a transmission of constant velocity rotating motion is required. The common types of constant velocity joints are plunging tripod, a fixed tripod, a plunging ball joint and a fixed ball joint. These types of joints are currently used in front wheel drive vehicles, rear wheel drive vehicles and on propeller shafts found in rear wheel drive, all wheel drive, and four wheel drive vehicles. The constant velocity joints are generally grease lubricated for life and sealed by a sealing boot when used on driveshafts or half shafts. Therefore, constant velocity joints are sealed in order to retain grease inside the joint and keep contaminates, such as dirt and water out of the joint. To achieve this protection the constant velocity joint is usually enclosed at the opened end of an outer race by a sealing boot made of a rubber, thermoplastic, or silicone type material. The opposite end of the outer race generally is enclosed by a dome or cap, known as a grease cap in the case of a disc-type joint. A mono block or integral stem and race design style joint is sealed by the internal geometry of the outer race. Sealing and protection of the constant velocity joint is necessary because contamination of the inner chamber of the joint generally will cause damage to the joint. 
     A main function of the constant velocity joint is the transmission of rotational forces and torque. A plunging joint will transmit rotational velocity while permitting relative axial displacement within the joint. Generally, a tripod joint operates as a plunging constant velocity joint while providing some degree of axial articulation. In typical joint assemblies, a variety of bolted joint designs are used to assemble a joint to a propeller shaft or halfshaft (sideshaft) within the automotive vehicle. These propeller shaft and halfshaft assemblies are typically assembled prior to installation within a driveline of a vehicle. 
     When a propeller shaft is installed within a vehicle, the maximum angle between the ends of the individual joints is limited by other components of the driveline and the vehicle. Before an assembled propeller shaft is installed into a vehicle, the individual joints may be manipulated into configurations that include angles between the ends of the individual joints that exceed the maximum angles experienced during operation. Excessive manipulation may result in configurations of individual joints that may damage components, such as the joint boot. Of concern is the boot of a tripod joint in a propeller shaft where the tripod joint geometry allows the shaft of the tripod joint to pinch a portion of the flexible boot, possibly damaging the boot and reducing the expected boot life. Therefore, a need exists for a system for limiting the articulation (non-axial angular rotation of the shaft) of a tripod joint, or other joints, to prevent boot damage prior to and during propeller shaft installation. 
     DISCLOSURE OF THE INVENTION 
     The present application discloses a joint apparatus having an outer joint portion having an opening end, an outer joint axis, and an outer joint inside surface defining, at least in part, an internal vault. The joint apparatus also includes an inner joint portion including a spider interposed within the outer joint portion and a shaft, defining a shaft axis, extending through the opening end. The spider includes a trunnion. The trunnion is at least partially interposed within the vault. The inner joint portion includes an angular range of motion limiting device that selectively restricts articulation of the joint. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Referring now to the drawings, illustrative embodiments are shown in detail. Although the drawings represent some embodiments, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present invention. Further, the embodiments set forth herein are not intended to be exhaustive or otherwise limit or restrict the claims to the precise forms and configurations shown in the drawings and disclosed in the following detailed description. 
         FIG. 1  is a top view of a driveline system. 
         FIG. 2  is a partial sectional top view of the propeller shaft illustrated in  FIG. 1 . 
         FIG. 3  is a partial sectional view of a portion of the propeller shaft of  FIG. 2 . 
         FIG. 4  is an exploded perspective view of a portion of a propeller shaft of  FIG. 2 . 
         FIG. 5  is a sectional view taken along broken line  5 - 5  of  FIG. 3 , with some section graphics removed for clarity. 
         FIG. 6  is a partial sectional view of a portion of a prior art propeller shaft. 
         FIG. 7  is a partial sectional view of a portion of a propeller shaft. 
         FIG. 8  is a partial sectional view taken along line  8 - 8  of  FIG. 7 . 
         FIG. 9  is a partial sectional view of a portion of a propeller shaft. 
         FIG. 10  is a sectional view of the portion of a propeller shaft. 
         FIG. 11  is a partial sectional view of a portion of a propeller shaft. 
         FIG. 12  is a partial sectional view of a portion of a propeller shaft. 
         FIG. 13  is a sectional view of the portion of the propeller shaft of  FIG. 12  illustrated in a second configuration. 
         FIG. 14  is a sectional view taken along line  14 - 14  of  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a driveline  20  of a vehicle (not shown). The driveline  20  includes an engine  22  that is connected to a transmission  24  and a power take off unit  26 . A front differential  32  has a right hand front half shaft  34  and a left hand front half shaft  36 , each of which are connected to a wheel  38  and delivers power to those wheels  38 . The power take off unit  26  has a propeller shaft  40  and a front wheel propeller shaft  42  extending therefrom. The front wheel propeller shaft  42  connects the front differential  32  to the power take off unit  26 . The propeller shaft  40  connects the power take off unit  26  to a rear differential  44 , wherein the rear differential  44  includes a rear right hand side shaft  46  and a rear left hand side shaft  48 , each of which ends with a wheel  38  on one end thereof. 
     The propeller shaft  40 , as best seen in  FIG. 2 , includes a front propeller shaft  52 , a rear propeller shaft  54 , an articulated tripod joint  50  and two high speed constant velocity joints  60 . The front propeller shaft  52  is defined by an axis A-A, and the rear propeller shaft  54  is defined by an axis B-B. The constant velocity joints  60  transmit power even if the wheels  38  or the shafts have changing angles due to steering and suspension jounce and rebound. Constant velocity joints  60  are also located on both ends of the half shafts  46 ,  48  that connect to the wheel  38  and the rear differential  44 . Also, both ends of the right hand front half shaft  34  and left hand front half shaft  36  include constant velocity joints  60 . 
     The constant velocity joints  60  may be of any of the standard types known, such as plunging tripod, cross groove joint, fixed ball joint, fixed tripod joint, or double offset joints, all of which are commonly known terms in the art for different varieties of constant velocity joints. The constant velocity joints  60  allow for transmission of constant velocities at angles which are found in everyday driving of automotive vehicles in both the halfshafts (sideshafts) and propeller shafts of these vehicles. 
     The driveline  20  represents an all wheel drive vehicle, however it should be noted that the embodiment of the constant velocity joints  60  of the current invention can also be used in rear wheel drive vehicles, front wheel drive vehicles, all wheel drive vehicles and four wheel drive vehicles. 
     As best seen in  FIGS. 3-5 , the joint  50  includes a tulip, or an outer joint portion  70 , connected to the front propeller shaft  52 , and an inner joint portion  72 . The inner joint portion  72  includes a shaft  74  connected to the rear propeller shaft  54 . The inner joint portion  72  also includes a tripod, or spider,  76  splined to the shaft  74 . As best seen in  FIG. 2 , the tulip  70  is also generally defined by the axis A-A of the front propeller shaft  52  and the shaft  74  is also generally defined by the axis B-B the rear propeller shaft  54 . 
     The tulip  70  is provided with an inner recess  84  having three uniformly circumferentially distributed vaults  86 . The vaults  86  form pairs of circumferentially opposed tracks  88  connected by a vault major surface  90  that extend from an opening end  94  of the tulip  70  to an annular wall  96 . The tracks  88  of adjacent vaults  86  are connected by a tulip minor surface  92 . The spider  76  includes an annular hub portion  100  provided with an aperture  102  for inserting the shaft  74  therein and three uniformly circumferentially distributed trunnion lands  104 . As illustrated, the spider  76  is splined to the shaft  74  for rotation therewith. Extending from the hub portion  100  (at each trunnion land  104 ) are three uniformly circumferentially distributed trunnions  106  having axes T 1 , T 2 , and T 3  having a trunnion crown  108  at a distal end. One trunnion  106  is interposed into each vault  86 . A roller assembly  110  is interposed within each vault  86  with a trunnion  106  interposed therein. Each trunnion  106  includes a trunnion groove  112  formed therein. Each roller assembly  110  includes bearing needles  116  and rollers  118 . 
     Each roller  118  with bearing needles  116  are axially restrained on each trunnion  106  by a retaining washer  120  and a securing ring  122 . The securing ring  122  is retained within one trunnion groove  112  of each trunnion  106 . In conjunction with the retaining washer  120 , the securing ring  122  restrains each bearing needle  116  and roller  118  on each trunnion  106 . The roller assemblies  110  are permitted to axially float along axes T 1 , T 2 , T 3  between contact with the trunnion lands  104  and the securing rings  120 . Generally, the vault major surface  90  is defined by a first vault diameter DV, and the tulip minor surface  92  is defined by a second vault diameter dv ( FIG. 5 ). Each trunnion  106  includes a cylindrical outer surface  124  and a trunnion end  126 . When the spider  76  is positioned concentric to the tulip  70 , a clearance C is generally provided between each trunnion end  126  and vault major surface  90  ( FIGS. 3 and 5 ). 
     As best illustrated in  FIG. 5 , the joint  50  may be trisected about the axes A-A and B-B into three generally equal portions. Each trunnion is generally defined by a trunnion radius TH extending to the trunnion end  126 . When the joint  50  is in operation with the tulip  70  and shaft  74  generally axially aligned, the rotational forces within the joint  50  urge the axes A-A and B-B to be co-axial and the trunnions float within the roller assemblies  110  to provide a generally equal clearance C between each trunnion end  126  and vault major surface  90 . That is, generally, the trunnion radius TH added to the clearance C will equal the first vault diameter DV. 
     As best seen in  FIG. 3 , the joint  50  also includes a boot assembly  130 . The boot assembly  130  includes a boot can  132  and a flexible boot  134 . The flexible boot  134  includes an outer bead end  140 , an inner shaft end  142 , a flexible portion  144  extending therebetween, an outer boot surface  146 , and an inner boot surface  148 . The boot can  132  includes a crimped end  150  that is folded over the bead end  140 , a tulip end  152  connected to the tulip  70 , a generally cylindrical can body  154  extending therebetween, an outer can surface  156 , and an inner can surface  158 . 
       FIG. 6  illustrates the propeller shaft of  FIGS. 1-5  in a prior art configuration, wherein like elements have like numbers. In the prior art configuration, the axis A-A of the front tulip  70  is not aligned with the axis B-B of the shaft  74 . In the configuration illustrated, the joint  50  cannot rotate to the prior art configuration when installed in the driveline  20 , but can only articulate to the prior art configuration when not fully installed in driveline  20  since the articulation of an assembled joint  50  is not limited prior to installation. When fully installed in the driveline  20 , the joint  50  is permitted to articulate while being limited by the positioning of the shafts  52 ,  54  to a third configuration (not shown) that is an intermediate position between the axial alignment of  FIG. 3  and the unhindered articulation of  FIG. 6 . That is, operation of the driveline  20  will desirably not involve interference of driveline components, such as contact between shaft  74  and front tulip  70 , and generally the joints, such as joint  50  are dimensioned such that this contact will not occur with maximum articulation permitted by the driveline  20  as limited by the components of the driveline  20  that are generally fixed to the vehicle. 
     As best seen in comparing  FIGS. 3 and 6 , the clearance C between each trunnion end  126  and vault major surface  90  permits the shaft  74  to articulate relative to the tulip  70 . However,  FIG. 6  illustrates that the shaft  74  may articulate relative to the tulip  70  until the outer can surface  156  of the crimped end  150  of the boot can  132  contacts the outer boot surface  146  of the boot  134 . This contact may result in damage to the boot  134  up to and including failure of the boot  134  to operate as intended. Damage experienced has included undesired lacerated portions of the boot  134 . 
       FIGS. 3 and 6  also illustrate that the tulip  70  may be axially displaced relative to the shaft  74 . When the joint  50  is not fully installed, this relative axial displacement is limited by contact between the shaft  74  and/or spider  76  and wall  96  at a full shaft insertion configuration (not shown) and extension of the boot  134  at a shaft extended configuration (not shown). Damage to the boot may occur at various amounts of axial displacement between the tulip  70  and the shaft  74  between the full shaft insertion configuration and the shaft extended configuration when the joint  50  is not fully installed. When fully installed ( FIG. 1 ), the plunge of joint  50  includes relative axial displacement between the shaft  74  and tulip  70  that is not limited by contact or interference between components of the joint  50 . That is, when fully installed in the driveline  20 , the joint  50  is limited by other components of the driveline  20  and not permitted to plunge to either the full shaft insertion configuration or the shaft extended configuration. 
       FIG. 7  illustrates a joint  250 . The joint  250  includes a tulip, or an outer joint portion,  270  connected to a front propeller shaft, such as the front propeller shaft  52 , and an inner joint portion  272 . The inner joint portion  272  includes a shaft  274  connected to a rear propeller shaft, such as the rear propeller shaft  54 . The inner joint portion  272  also includes a tripod, or spider,  276  splined to the shaft  274 . The tulip  270  is generally defined by an axis A 1 -A 1  and the shaft  274  is generally defined by an axis B 1 -B 1 . The tulip  270  may be axially displaced relative to the shaft  274  during operation of the driveline  20 , and at other times, including transport and assembly of a propeller shaft, such as propeller shaft  40 . 
     The tulip  270  is provided with an inner recess  284  having three uniformly circumferentially distributed vaults  286 . The vaults  286  form pairs of circumferentially opposed tracks  288  connected by a first inner surface, or vault major surface,  290  that extend from an opening end  294  of the tulip  270  to an annular wall  296 . The tracks  288  of adjacent vaults  286  are connected by a second inner surface, or tulip minor surface,  292 . The spider  276  includes an annular hub portion  300  provided with an aperture  302  for inserting the shaft  274  therein and three uniformly circumferentially distributed trunnion lands  304 . As illustrated, the spider  276  is splined to the shaft  274  for rotation therewith. Extending from the hub  300  (at each trunnion land  304 ) are three uniformly circumferentially distributed trunnions  306  having a trunnion crown  308  at a distal end. 
     One trunnion  306  is interposed within each vault  286 . A roller assembly  310  is interposed within each vault  286  with a trunnion  306  interposed therein. Each roller assembly  310  includes bearing needles  316  and rollers  318 . Each roller  318  with bearing needles  316  is axially restrained on each trunnion  306  by a securing ring  320 . The roller assemblies  310  are permitted to axially float between contact with the trunnion lands  304  and the securing rings  320 . 
     Generally, the vault major surface  290  is defined by a first vault diameter DV, and the tulip minor surface  292  is defined by a second vault diameter dv (as indicated in  FIG. 5 ). Each trunnion  306  includes a generally cylindrical outer surface  324  and a trunnion end  326 . That is, each trunnion  306  is defined by a generally cylindrical surface that extends between a trunnion land  304  and a trunnion crown  308 , where the trunnion crown  308  includes the trunnion end  326 . When the spider  276  is positioned concentric to the tulip  270 , a clearance is generally provided between each trunnion end  326  and vault major surface  290 . The clearance between each trunnion end  326  and vault major surface  290  permits the shaft  274  to articulate relative to the tulip  270 . 
       FIG. 8  illustrates the joint  250  with spider  276  removed and the shaft  274  centered therein for clarity. As best seen in  FIG. 8 , the joint  250  may be trisected about the axes A 1 -A 1  and B 1 -B 1  into three generally equal portions. When the joint  250  is in operation with the tulip  270  and shaft  274  generally axially aligned, the rotational forces within the joint  250  urge the axes A 1 -A 1  and B 1 -B 1  to be co-axial and the trunnions float within the roller assemblies  310  to provide a generally equal clearance between each trunnion end  326  and vault major surface  290 . 
     Referring again to  FIG. 7 , the joint  250  also includes a boot assembly  330 . The boot assembly  330  includes a boot can  332  and a flexible boot  334 . The flexible boot  334  includes an outer bead end  340 , an inner shaft end  342 , a flexible portion  344  extending therebetween, an outer boot surface  346 , and an inner boot surface  348 . The boot can  332  includes a crimped end  350  that is folded over the bead end  340 , a tulip end  352  connected to the tulip  270 , a generally cylindrical can body  354  extending therebetween, an outer can surface  356 , and an inner can surface  358 . 
       FIGS. 7 and 8  illustrate that the joint  250  may also include a limiting device, or limiting portion,  360 . In the embodiment illustrated, the limiting portion  360  is a generally annular ring having a inner ring surface  364  ( FIG. 8 ) generally fixed (splined or pressed) to the shaft  274 , and a generally cylindrical outer limiting surface  368 . In  FIG. 7 , the axis A 1 -A 1  of the front tulip  270  is not aligned with the axis B 1 -B 1  of the shaft  274  and the outer limiting surface  368  of the limiting portion  360  is in contact with the tulip minor surface  292 . As the outer limiting surface  368  of the limiting portion  360  contacts the tulip minor surface  292 , the trunnion end  326 , sectionally illustrated in  FIG. 7 , will not contact the vault major surface  290  in the embodiment illustrated. As best seen in  FIG. 8 , the outer limiting surface  368  of the limiting portion  360  may contact two tulip minor surfaces  292  if the shaft  274  were articulated in the direction of arrow D 8 . Accordingly, articulation between the shaft  274  and the tulip  270  is arrested when the outer limiting surface  368  of the limiting portion  360  is in contact with at least one tulip minor surface  292 . 
     Therefore, the contact between the limiting portion  360  and the tulip  270  prevents the outer can surface  356  of the crimped end  350  of the boot can  332  from contacting the outer boot surface  346  of the boot  334  during articulation of the shaft  274  relative to the tulip  270 . This lack of contact between the crimped end  350  and the outer boot surface  346  prevents undesired damage to the boot  334 . 
     When a propeller shaft, such as the propeller shaft  40 , is assembled with a joint  250 , manipulation of the propeller shaft when not fully installed in the driveline  20  will not result in damage to the boot  334  by the boot can  332 . The outer limiting surface  368 , while illustrated as generally cylindrical, may be curved, or generally toroidal, or any other suitable shape. 
       FIG. 9  illustrates a joint  450 . The joint  450  includes a tulip, or an outer joint portion,  470  connected to a front propeller shaft, such as the front propeller shaft  52 , and an inner joint portion  472 . The inner joint portion  472  includes a shaft  474  connected to a rear propeller shaft, such as the rear propeller shaft  54 . The inner joint portion  472  also includes a tripod, or spider,  476  splined to the shaft  474 . The tulip  470  is generally defined by an axis A 2 -A 2  and the shaft  474  is generally defined by an axis B 2 -B 2 . The tulip  470  may be axially displaced relative to the shaft  474 . 
     The tulip  470  is provided with an inner recess  484  having three uniformly circumferentially distributed vaults  486 . The vaults  486  form pairs of circumferentially opposed tracks  488  connected by an vault major surface  490  that extend from an opening end  494  of the tulip  470  to an annular wall  496 . The tracks  488  of adjacent vaults  486  are connected by a tulip minor surface  492 . The spider  476  includes an annular hub portion  500  provided with an aperture  502  for inserting the shaft  474  therein, and three uniformly circumferentially distributed trunnion lands  504 . Extending from the hub  500  are three uniformly circumferentially distributed trunnions  506 . One trunnion  506  is interposed into each vault  486 . A roller assembly  510  is interposed within each vault  486  with a trunnion  506  interposed therein. Each roller assembly  510  includes bearing needles  516  and rollers  518 . Each roller  518  with bearing needles  516  are axially restrained on each trunnion  506  by a securing ring  520 . 
     Each trunnion  506  includes a cylindrical outer surface  524  and a trunnion end  526 . When the spider  476  is positioned concentric to the tulip  470 , a clearance is generally provided between each trunnion end  526  and vault major surface  490 . The clearance between each trunnion end  526  and vault major surface  490  permits the shaft  474  to articulate relative to the tulip  470 . 
     The joint  450  also includes a boot assembly  530 . The boot assembly  530  includes a boot can  532  and a flexible boot  534 . The flexible boot  534  includes an outer bead end  540 , an inner shaft end  542 , a flexible portion  544  extending therebetween, an outer boot surface  546 , and an inner boot surface  548 . The boot can  532  includes a crimped end  550  that is folded over the bead end  540 , a tulip end  552  connected to the tulip  470 , a generally cylindrical can body  554  extending therebetween, and a can outer surface  556 . 
     The joint  450  also includes a limiting portion  560 . As illustrated in  FIG. 9 , the limiting portion  560  is an annular ring with a generally cylindrical outer limiting surface  568  that is attached to the shaft  474 . The limiting portion  560  extends from the shaft  474  between the spider  476  and the wall  496 , although the limiting portion  560  may be positioned between the spider  476  and the opening end  494 . As illustrated, the axis A 2 -A 2  of the tulip  470  is not aligned with the axis B 2 -B 2  of the shaft  474  and the outer limiting surface  568  of the limiting portion  560  is in contact with the tulip minor surface  492 . As the outer limiting surface  568  of the limiting portion  560  contacts the tulip minor surface  492 , the trunnion end  526 , may contact the vault major surface  490 . The articulation of the shaft  474  relative to the tulip  470  is arrested when the outer limiting surface  568  of the limiting portion  560  is in contact with the tulip minor surface  492  and when one trunnion end  526  may be in contact with the vault major surface  490 . 
     Therefore, the contact between the limiting portion  560  and the tulip  470  prevents the crimped end  550  of the boot can  532  from contacting the outer boot surface  546  of the boot  534  during articulation of the shaft  474  relative to the tulip  470 . This lack of contact between the crimped end  550  and the outer boot surface  546  prevents undesired damage in the boot  534 . 
     When a propeller shaft, such as the propeller shaft  40 , is assembled with a joint  450 , manipulation of the propeller shaft when not fully installed in the driveline  20  will not result in damage to the boot  534  by the boot can  532 . The outer limiting surface  568 , while illustrated as generally cylindrical, may be curved or generally toroidal, or any other suitable shape. 
       FIG. 10  illustrates an alternative of the limiting portion  560  as a limiting portion  600  positioned within the joint  450 , with the spider  476  removed and the shaft  474  centered within the tulip  470  for clarity. The limiting portion  600  includes three generally equally circumferentially spaced lobes  610  each having an distal diameter lobe surface  612  and a pair of opposing surfaces  614 . The lobes  610  are separated by three proximal diameter surfaces  616 . As illustrated generally centered in the joint  450 , the lobes  610  extend from the limiting portion  600  toward the vault major surface  490  with a clearance C 4  between the vault major surface  490  and the distal diameter lobe surface  612 . Also, a clearance C 5 , measured generally radially to the axis B 2 -B 2 , is provided between the tulip minor surface  492  and the proximal diameter surfaces  616 . Generally, the vault major surface  490  is defined by a first vault diameter DV, and the tulip minor surface  492  is defined by a second vault diameter dv (as indicated in  FIG. 10 ). Also, the distal diameter lobe surfaces  612  define an outer lobe diameter DL and the proximal diameter surfaces  616  define a proximal diameter DP. As illustrated, the first vault diameter DV is larger than the outer lobe diameter DL which is larger than the second vault diameter dv which is larger than the proximal diameter DP. 
     In operation, the limiting portion  600  limits the articulation of the tulip  470  relative to the shaft  474 . When articulation of the tulip  470  relative to the shaft  474  moves the limiting device in direction D 2  relative to at least a portion of the tulip  470 , the vault major surface  490  will contact the distal diameter lobe surface  612 , thereby preventing further articulation. When articulation of the tulip  470  relative to the shaft  474  moves the limiting device in direction D 1 , the tulip minor surface  492  will contact the proximal diameter surfaces  616 , thereby preventing further articulation. As in the illustrative example of  FIG. 7 , the articulation of the tulip  270  relative to the shaft  274  where the limiting portion  360  prevents contact between the boot can  332  and the boot  334 , the limiting device  600  prevents damage to the boot  534  when installed in a joint  450 . 
     While the limiting device  600  is illustrated as positioned between the spider  476  and the wall  496  (between the spider  476  and a front propeller shaft, such as the front propeller shaft  52 ), the limiting device  600  may be positioned between the spider  476  and the opening end  494  (between the spider  476  and a rear propeller shaft, such as the rear propeller shaft  54 ). 
       FIG. 11  illustrates another embodiment of a joint  50  as a joint  650 . The joint  650  includes a tulip, or an outer joint portion,  670  connected to a front propeller shaft, such as the front propeller shaft  52 , and an inner joint portion  672 . The inner joint portion  672  includes a shaft  674  connected to a rear propeller shaft, such as rear propeller shaft  54 . The inner joint portion  672  also includes a tripod, or spider,  676  splined to the shaft  674 . The tulip  670  is generally defined by an axis A 3 -A 3  and the shaft  674  is generally defined by an axis B 3 -B 3 . The tulip  670  may be axially displaced relative to the shaft  674 . 
     The tulip  670  is provided with an inner recess  684  having three uniformly circumferentially distributed vaults  686 . The vaults  686  form pairs of circumferentially opposed tracks  688  connected by an vault major surface  690  that extend from an opening end  694  of the tulip  670  to an annular wall  696 . The tracks  688  of adjacent vaults  686  are connected by a tulip minor surface  692 . The spider  676  includes an annular hub portion  700  provided with an aperture  702  for inserting the shaft  674  therein and three uniformly circumferentially distributed trunnion lands  704 . Extending from the hub  700  are three uniformly circumferentially distributed trunnions  706 . One trunnion  706  is interposed into each vault  686 . A roller assembly  710  is interposed within each vault  686  with a trunnion  706  interposed therein. Each roller assembly  710  includes bearing needles  716  and rollers  718 . Each roller  718  with bearing needles  716  are axially restrained on each trunnion  706  by a securing ring  720 . 
     Each trunnion  706  includes a trunnion end  726 . When the spider  676  is positioned concentric to the tulip  670 , a clearance is generally provided between each trunnion end  726  and vault major surface  690 . The clearance between each trunnion end  726  and vault major surface  690  permits the shaft  674  to articulate relative to the tulip  670 . 
     The joint  650  also includes a boot assembly  730 . The boot assembly  730  includes a boot can  732  and a flexible boot  734 . The flexible boot  734  includes an outer bead end  740 , an inner shaft end  742 , a flexible portion  744  extending therebetween, an outer boot surface  746 , and an inner boot surface  748 . The boot can  732  includes a crimped end  750  that is folded over the bead end  740 , a tulip end  752  connected to the tulip  670 , a generally cylindrical can body  754  extending therebetween, and a can outer surface  756 . 
     The joint  650  also includes a pair of limiting portions  760 ,  762 . In the embodiment illustrated, the limiting portions  760 ,  762  are annular rings with respective generally cylindrical outer limiting surfaces  770 ,  768  that are attached to the shaft  670 . In the embodiment illustrated, the axis A 3 -A 3  of the tulip  670  is not aligned with the axis B 3 -B 3  of the shaft  674  and the outer limiting surface  770  of the limiting portion  760  is in contact with the tulip minor surface  692 . 
     As the shaft  674  is non-axially rotated relative to the tulip  670 , the outer limiting surface  770  of the limiting portion  760  rotates toward the tulip minor surface  692 . When the outer limiting surface  768  of the limiting portion  762 , or the outer limiting surface  770  of the limiting portion  760 , contacts the tulip minor surface  692 , the trunnion end  726  may also contact the vault major surface  690 . The articulation between the shaft  674  and the tulip  670  is arrested when the outer limiting surface  768 ,  770  of the limiting portion  762 ,  760  is in contact with the tulip minor surface  692  and when one trunnion end  726  may be in contact with the vault major surface  690 . 
     Therefore, the contact between one of the limiting portions  760 ,  762  and the tulip  670  will limit the articulation of the shaft  674  relative to the tulip  670  and prevent the crimped end  750  of the boot can  732  from contacting the outer boot surface  746  of the boot  734  during articulation of the tulip  670  relative to the shaft  674 . This lack of contact between the crimped end  750  and the outer boot surface  746  prevents undesired damage in the boot  734 . 
     When a propeller shaft, such as the propeller shaft  40 , is assembled with a joint  650 , manipulation of the propeller shaft when not fully installed in the driveline  20  will not result in damage to the boot  734  by the boot can  732 . Again, while limiting portions  760 ,  762  are illustrated as generally cylindrical, they may be curved, generally toroidal or any other suitable shape. 
       FIGS. 12-14  illustrate a further embodiment of a joint  50  as a joint  850 . The joint  850  includes a tulip, or an outer joint portion,  870  connected to a front propeller shaft, such as the front propeller shaft  52 , and an inner joint portion  872 . The inner joint portion  872  includes a shaft  874  connected to a rear propeller shaft, such as the rear propeller shaft  54 . The inner joint portion  872  also includes a tripod, or spider,  876  splined to the shaft  874 . The tulip  870  is generally defined by an axis A 4 -A 4  and the shaft  874  is generally defined by an axis B 4 -B 4 . The tulip  870  may be axially displaced relative to the shaft  874  during operation of the driveline  20 , and at other times, including transport and assembly of a propeller shaft, such as propeller shaft  40 . 
     The tulip  870  is provided with an inner recess  884  having three uniformly circumferentially distributed vaults  886 . The vaults  886  form pairs of circumferentially opposed tracks  888  connected by a first inner surface, or vault major surface,  890  that extend from an opening end  894  of the tulip  870  to an annular wall  896 . The tracks  888  of adjacent vaults  886  are connected by a second inner surface, or tulip minor surface,  892 . The spider  876  includes an annular hub portion  900  provided with an aperture  902  for inserting the shaft  874  therein and three uniformly circumferentially distributed trunnion lands  904 . As illustrated, the spider  876  is splined to the shaft  874  for rotation therewith. Extending from the hub  900  at each trunnion land  904  are three uniformly circumferentially distributed trunnions  906  having axes T 1 , T 2 , and T 3  (see  FIG. 14 ) having a trunnion crown  908  at a distal end. 
     One trunnion  906  is interposed within each vault  886 . A roller assembly  910  is interposed within each vault  886  with a trunnion  906  interposed therein. Each roller assembly  910  includes bearing needles  916  and rollers  918 . Each roller  918  with bearing needles  916  is axially restrained on each trunnion  906  by a securing ring  920 . The roller assemblies  910  are permitted to axially float along axes T 1 , T 2 , T 3  between contact with the trunnion lands  904  and the securing rings  920 . As illustrated, the rollers  918  mate with the tracks  888  at engaging curved surfaces. 
     Each trunnion  906  includes a generally cylindrical outer surface  924  and a trunnion end  926 . That is, each trunnion  906  is defined by a generally cylindrical surface that extends between a trunnion land  904  and a trunnion crown  908 , where the trunnion crown  908  includes the trunnion end  926 . When the spider  876  is positioned concentric to the tulip  870 , a clearance C 8  is generally provided between each trunnion end  926  and vault major surface  890 . The clearance C 8  between each trunnion end  926  and vault major surface  890  permits the shaft  874  to articulate relative to the tulip  870 . 
     As illustrated in  FIG. 14 , the joint  850  may be trisected about the axes A 4 -A 4  and B 4 -B 4  into three generally equal portions. When the joint  850  is in operation with the tulip  870  and shaft  874  generally axially aligned, the rotational forces within the joint  850  urge the axes A 4 -A 4  and B 4 -B 4  to be co-axial and the trunnions float within the roller assemblies  910  to provide a generally equal clearance C 8  between each trunnion crown  908  and vault major surface  890 . 
     Generally, the vault major surface  890  is defined by a first vault diameter DV, and the tulip minor surface  892  is defined by a second vault diameter dv (as indicated in  FIG. 14 ). The hub  900  defines an outer hub diameter DH. 
     A trunnion radius DS is measured between the axis B 4 -B 4  and the trunnion end  926 . That is, the outermost portion of the trunnion  906  extending from the rotation point along axis B 4 -B 4  is a distance DS from the axis B 4 -B 4 . Accordingly, when the trunnion height DS is increased for a joint, such as the joint  850 , the maximum angle of articulation (measured between axis A 4 -A 4  and axis B 4 -B 4  of  FIG. 13 ) is decreased. As an example, a trunnion radius DS of 31.011 millimeters (mm) and a first vault diameter DV of 62.60 mm would result in an angle of articulation of about 22 degrees. In this example, the joint would not articulate beyond a relative angle between axis A 4 -A 4  and axis B 4 -B 4  of about 22 degrees. Further, the operation of this joint within a driveline, such as the driveline  20 , would not require articulation beyond 22 degrees. In this example, the ratio of the vault diameter DV to the trunnion radius DS would be about 2.02. The present invention defines a ratio of the vault diameter DV to the trunnion radius DS of about 1.95 to about 2.05 as desirable, while a ratio of the vault diameter DV to the trunnion radius DS of about 1.98 to about 2.02 as more desirable. 
     The joint  850  also includes a boot assembly  930 . The boot assembly  930  includes a boot can  932  and a flexible boot  934 . The flexible boot  934  includes an outer bead end  940 , an inner shaft end  942 , a flexible portion  944  extending therebetween, an outer boot surface  946 , and an inner boot surface  948 . The boot can  932  includes a crimped end  950  that is folded over the bead end  940 , a tulip end  952  connected to the tulip  870 , a generally cylindrical can body  954  extending therebetween, an outer can surface  956 , and an inner can surface  958 . 
       FIGS. 12-14  illustrate that the joint  850  may also include a limiting portion  960 . In the embodiment illustrated, the limiting portion  960  includes three outer limiting surfaces  968  which are defined by the trunnion crowns  908  and the trunnion ends  926 . The outer limiting surface  968 , while illustrated as generally cylindrical, may be curved, or generally toroidal, or any other suitable shape.  FIGS. 12 and 14  illustrate the joint  850  in a first configuration where the axis A 4 -A 4  of the front tulip  870  is generally aligned with the axis B 4 -B 4  of the shaft  874 . 
       FIG. 13  illustrates the joint  850  in a limited configuration. In the limited configuration, the axis A 4 -A 4  of the front tulip  870  is not aligned with the axis B 4 -B 4  of the shaft  874  and a trunnion crown  908  of the limiting portion  960  is in contact with the vault major surface  890 . Articulation between the shaft  874  and the tulip  870  is arrested when the outer limiting surface  968  of the crown  908  of the limiting portion  960  is in contact with the vault major surface  890 . 
     Therefore, the contact between the limiting portion  960  and the tulip  870  prevents the outer can surface  956  of the crimped end  950  of the boot can  932  from contacting the outer boot surface  946  of the boot  934  during articulation of the tulip  870  relative to the shaft  874 . This lack of contact between the crimped end  950  and the outer boot surface  946  prevents undesired damage to the boot  934 . 
     In the limited configuration illustrated in  FIG. 13 , the hub  900  does not contact the tulip minor surface  892  although the hub may contact the tulip minor surface in other embodiments. As illustrated in the limited configuration of  FIG. 13 , and with reference to  FIG. 14 , when the shaft  874  is rotated in the direction D 13  relative to the tulip  870 , the spider  876  rotates the rollers  918 , and the rollers  918  interposed on trunnions  906  defining axes T 2  and T 3  will limit radial movement of the spider  876  as the limiting portion  960  contacts the roller  918  interposed on the trunnion  906  defining axis T 1 , and the rollers  918  interposed on trunnions  906  defining axes T 2  and T 3  contact their respective trunnion lands  904  and the rollers  918  interposed on trunnions  906  defining axes T 2  and T 3  are limited in moving along axes T 2  and T 3  due to the interaction between the curved surfaces of the rollers  918  and the tracks  888 . 
     When a propeller shaft, such as the propeller shaft  40 , is assembled with a joint  850 , manipulation of the propeller shaft when not fully installed in the driveline  20  will not result in damage to the boot  934  by the boot can  932 . 
     While  FIG. 6  illustrates that shaft  74  may articulate relative to the tulip  70  until the outer can surface  156  of the crimped end  150  of the boot can  132  contacts the outer boot surface  146  of the boot  134 , contact with or damage to a boot may not be of concern when using limiting portions, such as the limiting portions  360 ,  560 ,  760 ,  762  and/or  960  to limit articulation of joints. That is, limiting articulation of joints need not be directed to the illustrative applications presented herein. 
     The portions  360 ,  560 ,  760 ,  762 ,  960  permit a desired amount of articulation of the joint when installed, while preventing undesired angles of articulation that may result in damage to the boot. In the embodiments illustrated, the limiting portions  360 ,  560 ,  760 ,  762  are metal alloy, although other materials, such as high density polyethylene (HDPE) may be used. While the limiting portions  360 ,  560 ,  760 ,  762  are illustrated and described herein as fixed to a shaft, the limiting devices may axially rotate relative to the shaft, may axially translate relative to the shaft, or may otherwise move relative to the shaft. Additionally, the outer surfaces of the rollers  118 ,  318 ,  518 ,  718 ,  918 , while illustrated in various shapes such as cylindrical, curved and spherical, may be any suitable shape, and may limit radial movement of the spiders  76 ,  276 ,  476 ,  676 ,  876  as described herein, to work in conjunction with the limiting devices described herein. 
     As used herein, articulation of a joint involves non-axial rotation of one portion of the joint relative to another portion of the joint. Generally, this involves non-axial rotation as viewed, for example, in comparing  FIG. 12  to  FIG. 13 . 
     The preceding description has been presented only to illustrate and describe exemplary embodiments of the methods and systems of the present invention. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. The invention may be practiced otherwise than is specifically explained and illustrated without departing from its spirit or scope. The scope of the invention is limited solely by the following claims.

Technology Category: f