Abstract:
A vehicle, such as off road vehicle, includes a plunge pin assembly located in a flexible joint, which maybe actuated without tools to decouple and thus remove a driven system from a driving system. The plunge pin assembly includes a plunge pin biased to an installed position such that a clip of the plunge pin assembly retains the driven system to the driving system during operation of a vehicle. The clip (e.g., circlip, snap ring, coil spring or crest wave spring) is circumferentially contractable and expandable. A transfer element cooperates with tapered and recessed contours of the plunge pin to permit the aforementioned actuation of the clip. Movement of the transfer pin along with contraction of the clip allows the driven system to be decoupled from the driving system. The plunge pin may include a head portion positioned at a desired distance from a drive axle of the driven system.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to a biased plunge pin assembly operable by hand (e.g., without tools) to permit removal and replacement of a driven system from a driving system of a vehicle. 
     BACKGROUND OF THE INVENTION 
     All-terrain vehicles (ATVs) are meant to travel over rough terrain, in various conditions and at a variety of speeds. For handling and maneuverability purposes, ATVs are constructed to minimize weight. However, such construction can make various parts of the ATV more vulnerable to damage. One such part, for example, are the drive axles connecting the drivetrain to the wheels through a constant velocity, universal, or other type of flexible joint capable of transferring power between concentric or non-concentrically aligned shafts. More specifically, drive axles allow a rotating shaft to transmit power through a variable angle, at constant rotational speed, without an appreciable increase in friction or play. 
     Drive axles are typically installed with a spring clip that must either be removed or that must be “bumped” out of engagement with the driving system to which it is installed. In the case of such retaining means, removal and replacement of a drive axle requires one or more specialized tools and may be difficult to execute. 
     SUMMARY OF THE INVENTION 
     In at least one embodiment of the present invention, a plunge pin assembly is located in a flexible joint and may be actuated without tools to decouple and thus remove a driven system from a driving system. The plunge pin assembly includes a plunge pin normally biased to an installed position such that a clip of the plunge pin assembly retains the driven system to the driving system during operation of a vehicle. The clip, however, is circumferentially contractable and expandable and may take the form of a circlip or a snap ring. A transfer pin cooperates with tapered and recessed contours of the plunge pin to permit the aforementioned actuation of the clip, which in turn allows the driven system to be coupled or decoupled from the driving system without tools. In another embodiment, the plunge pin may include a head portion positioned at a desired distance from a drive axle of the driven system. Accordingly, applying an axial force onto the head portion of the plunge pin with the drive axle compresses a biasing member, axially moves the plunge pin, permits radial movement of the transfer pin into the recessed contour, and finally permits contraction of the clip that was previously engaged with the driving system. 
     In one aspect of the invention, a flexible joint engagable with a vehicle drive system component includes a housing having a first end with a flexible engagement assembly for engaging a driven shaft and a second end opposite the first end; a coupler shaft at the second end of the housing, the coupler shaft configured for engagement with the vehicle drive system component; a detent extending to an outer periphery of the coupler shaft and configured to engage the vehicle drive system component; a plunge pin disposed at least partially within the coupler shaft and movable relative thereto, the plunge pin biased toward the first end of the housing, the plunge pin having: a first portion contactable with the detent to maintain the detent in an engaged position with the vehicle drive system component; and a second portion adjacent the first portion, the second portion being recessed away from the outer periphery of the coupler shaft relative to the first portion; wherein movement of the plunge pin away from the first end of the housing aligns the second portion of the plunge pin with the detent to permit disengagement of the detent with the vehicle drive system. 
     In another aspect of the invention, an assembly for detachably coupling a driven system to a driving system includes a drive axle assembly; a flexible joint engagable with the driving system; a transfer pin arranged in the flexible joint to move relative to an axis of the drive axle assembly; a plunge pin located within the flexible joint, the plunge pin having a body extending between a transfer pin actuating portion and a head portion, the actuating portion having a recessed region configured to permit movement of the transfer pin; and a biasing member arranged in the flexible joint to bias the plunge pin toward a position where the driven system is retainably coupled with the driving system. 
     In yet another aspect of the invention, a vehicle having a driven system coupled to a driving system includes a halfshaft assembly coupled to the driving system, the halfshaft assembly having a drive axle and a flexible joint configured to transmit power from the driving system; and a plunge pin assembly coupled to the flexible joint, the plunge pin assembly having a detent mechanism, a plunge pin and a biasing member, the detent mechanism arranged in the flexible joint to move relative to an axis of the drive axle, the plunge pin having a body extending between an actuating portion and a head portion of the pin, the actuating portion having a tapered periphery configured to induce movement of the detent mechanism, and the biasing member arranged in the flexible joint to bias the plunge pin in a first direction in which the actuating portion urges the detent mechanism into engagement with driving system. 
     In still yet another aspect of the invention, a method for decoupling a driven system from a driving system includes the steps of (1) applying an axial force to a plunge pin assembly in a direction toward the driving system, the applied axial force sufficient to compress a biasing member and move the plunge pin; and (2) moving a detent mechanism toward an axis of the plunge pin, wherein moving the detent mechanism corresponds with movement of the plunge pin to disengage the driven system from the driving system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings. 
         FIG. 1  is a cross-sectional view of a driven system coupled to a driving system with a plunge pin assembly according to an embodiment of the present invention; 
         FIG. 2  is a side-elevational view of a halfshaft assembly with inboard and outboard flexible joints connected by an axle shaft and a plunge pin assembly located in the inboard flexible joint; 
         FIG. 3  is a partial side-elevational view of the halfshaft assembly of  FIG. 2  showing the plunge pin assembly biased in an installed position; 
         FIG. 4  is an isometric view of a plunge pin used in the plunge pin assembly of  FIG. 2  according to an embodiment of the present invention; 
         FIG. 5  is a flowchart for a method of decoupling a driven system from a driving system using a plunge pin assembly; and 
         FIG. 6  is a side-elevational view of a halfshaft assembly with inboard and outboard flexible joints connected by an axle shaft and a plunge pin assembly according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention includes a biased detent assembly that may be operated by hand (e.g., without tools), to permit removal and replacement of a coupler axle unit from a vehicle, such as, but not limited to an all-terrain vehicle. The coupler axle unit may include a shaft coupled to flexible joints and configured to transfer power through a variable shaft angle, at a constant input-to-output rotational speed ratio, without an appreciable increase in friction or play. Generally, the coupler axle unit operates in sync with the suspension system, the front, the rear or both. 
     The flexible joints may take the form of a constant velocity (CV) joint arranged in a driveline. The CV joint is characterized by having an output speed equal to its input speed at any joint angle. The CV joint may take the form of Undercut free joint, Rzeppa joint, Bell joint, Cross Groove joint, Weiss joint, Tripod joint or Double Offset joint. A non-CV joint is commonly referred to as a universal joint, a Cardan joint, or Double Cardan joint. The CV joint includes an outer race, an inner race, a cage and balls. 
       FIG. 1  shows a powertrain system  100  with a driving system  102  coupled to a driven system  104 . By way of example, the driving system  102  may take the form of a rear final drive while the driven system  104  may take the form of a halfshaft assembly with an articulating axle shaft  106  extending from a CV joint  108 . Thus in the illustrated embodiment, the articulated shaft  106  delivers power from the rear drive  102  to the wheels (not shown) through the CV joint  108  to allow for movement of the axle shaft  106  relative to rear drive  102  during suspension movement. 
     For various reasons such as, but not limited to, maintenance, inspection, or damage, it may be necessary to remove and replace one or more components of the driven system  104 . Accordingly, the driven system  104  includes a plunge pin assembly  110 , which includes a plunge pin  112 , a biasing member  114 , a transfer pin  116 , a first retaining device  118 , and a second retaining device  120 . 
       FIG. 2  shows the driven system  104  in the form of a drive axle system having an inboard flexible joint assembly  122  coupled to an outboard flexible joint assembly  124  through the axle shaft  106 . In the illustrated embodiment, the inboard flexible joint assembly  122  takes the form of a double offset joint, which will be described in more detail below, while the outboard flexible joint assembly  124  takes the form of a Rzeppa or bell joint. 
     By way of example, the Rzeppa joint  124  includes four main components: a housing  128 , a cage  130 , a race  132  and the ball bearings  134 . The housing  128  is generally constructed with six ball tracks (not shown) inside of a “bell” portion of the housing. The ball tracks allow for the ball bearings  134  to traverse with minimal friction and minimal heat generation. The ball bearings  134  are held between the race  132 , the cage  130 , and the housing  128 . There are generally six windows (not shown) in the cage  130  that are aligned with the six ball tracks of the housing  128 . The race  132  holds the ball bearings  134  in place by aligning its “legs” with the web between the windows in the cage  130 . The Rzeppa joint is extremely flexible and can accommodate large angular changes, for example when the front wheels of a vehicle are turned by a steering system. The typical Rzeppa joints allow 45-48 degrees of articulation, while some can allow 52 degrees. An outboard boot  136  may be coupled to the shaft  106  and the housing  128  to protect the other components of the outboard joint  124  from debris, dirt, and other contaminants. 
     Similar to the outboard flexible joint assembly  124 , the inboard flexible joint assembly  122  includes a housing  138 , a cage  140 , a race  142 , and the ball bearings  144 . However, it is important to note that the inboard flexible joint  122  is a plunge type joint meaning the shaft  106  is coupled to the housing  138  in a manner that allows for limited moving or “plunging” of the shaft  106  along the housing axis  146  relative to the housing  138 . The ball bearings  144 , in turn, are guided along grooves  141  formed in the housing  138 . As shaft  106  is plunged further within housing  138 , bearings  144  slide along grooves  141 . These same grooves allow shaft  106  to move in an axial direction during suspension movement relative to the drive and housing  138  during normal use of the ATV. An inboard boot  148  may be coupled to the shaft  106  and the housing  138  to protect the other components of the inboard joint  122  from debris, dirt and other contaminants. 
       FIG. 3  shows the inboard flexible joint assembly  122  having the plunge pin assembly  110 . For purposes of brevity, the parts of the inboard flexible joint assembly  122  described above will be provided with the same reference numerals, but are not described in further detail unless they specifically interact or cooperate with the plunge pin assembly  110 . 
     A coupling shaft  150  may extend from or be integrally formed with the housing  138 . The coupling shaft  150  includes outer splines that engage a spool in the drive  102  (see also  FIG. 1 ). The coupling shaft  150 , in turn, receives the plunge pin  112 , the biasing member  114 , the transfer pin  116 , the first retaining device  118  and the second retaining device  120 . In one embodiment, the biasing member  114  may take the form of a wave spring; the first retaining device  118  may take the form of a retaining ring; and the second retaining device  120  may take the form of a circlip, a snap ring, a coil spring or a crest wave spring. By way of example, the circlip, snap ring, coil spring or crest wave spring includes a semi-flexible metal ring with open ends which can be snapped into place into a groove formed in the housing  138  for clip  118  and in the coupling shaft  150  for clip  120 . The clip  120  prevents lateral (i.e., axial) movement of shaft  150  in the drive system and biases the transfer pins inward toward the axis of plunge pin  112 . Using a coil spring for the second retaining device  120  may be advantageous because the coil spring ends overlap, which eliminates any gap for the transfer pins to escape. 
       FIG. 4  shows the plunge pin  112  having a contact head portion  152 , a flange  154 , a body  156 , a necked down portion  158 , a tapered portion  160 , and a retaining portion  162 . The necked down portion  158  includes an outer diameter that is less than the outer diameter of the retaining portion  162 . The outer diameter of the tapered portion  160 , in turn, slopes in an increasing manner from the necked down portion  158  to the retaining portion  162 . The body  156  preferably includes a shoulder region  164  adjacent the necked down region  158 . In one embodiment, the contact head portion  152  may have a semi-spherical surface. In one embodiment, the flange  154  includes an outer diameter that is larger than or at least equal to an outer operating envelope of the biasing member  114  ( FIG. 3 ). The purposes of these plunge pin features are described hereinafter with respect to a method for removing the inboard flexible joint assembly  122  without tools. 
     Referring back to  FIG. 3  while continuing to reference  FIG. 4  for the plunge pin  112  features, the plunge pin  112  may be concentrically aligned with the axis  146  of the shaft  106 . A fastener  166  is also aligned with the axis  146  of the shaft  106 . A head  168  of the fastener  166  and the contact head portion  152  of the plunge pin  112  are arranged a desired distance  170  apart. 
     When the inboard flexible joint  122  is adequately installed (hereinafter referred to as an installed configuration), the head  168  of the fastener  166  and the contact head portion  152  of the plunge pin  112  are separated as noted above, and thus not in contact, even during the full range of suspension movement. In turn, the biasing member  114  is expanded such that the flange  154  is urged toward an inner cavity  172  of the housing  138  and the first retaining device  118  cooperates with the housing  138  to allow the contact head portion  152  of the plunge pin  112  to extend only a desired distance beyond an inner wall  174  of the housing  138 . The expansion of the biasing member  114  further forces an inner diameter portion of the transfer pin  116  to ride along and move radially outward due to the tapered portion  160  of the plunge pin  112 . In other words, the tapered portion  160  allows an outer diameter portion of the transfer pin  116  to radially move the second retaining device  120  (e.g., circlip, snap ring, coil spring or crest wave spring) into a retaining engagement with the driving system  102 , which in turn axially retains or secures the driven system  104  with respect to the driving system  102 . 
     Depending on the type of joint and the amount of retention desired, various aspects of the plunge pin assembly  110  may be adjusted or modified, for example the biasing forces of the biasing member  114  and the second retaining device  120 , the radial length of the transfer pin  116 , the necked down portion  158  of the plunge pin  112 , or the outer diameter of the retaining portion  162  of the plunge pin  112 . The amount of retention desired is generally the amount needed to secure the driven system  104  to the driving system  102  during vehicle operation while maintaining the spring force in the biasing member  114  at a level where the biasing member  114  may be compressed when plunging the shaft  106  by hand. Note that there are not normally large axially directed forces acting on the housing  138  and the coupling shaft  150  since ball bearings  144  are free to move along the grooves  141  in the housing  138  to allow for axial movement of shaft  106  along the housing axis during suspension travel. 
     In addition to achieving the desired amount of retention when in the installed configuration, the plunge pin assembly  110  may advantageously allow for the removal of the inboard flexible joint  122  from the drive system  102  without using any tools.  FIG. 5  shows such a tool-free method  200 . At step  202 , with vehicle suspension arms removed (not shown) an axial force is applied on the shaft  106  toward the inboard flexible joint  122  in a manner that moves the shaft  106  or fastener  166  (e.g., button) into contact with the plunge pin  112  (refer to  FIGS. 1 and 3 ). As discussed earlier, the inboard flexible joint  122  is configured to permit the shaft  106  to be plunged inward due to the configuration of the balls, races, cage, and housing. At step  204 , the shaft  106  operatively contacts the plunge pin  112 . In the present context, operatively contacts means the shaft  106  may not necessarily come into direct contact with the plunge pin  112 , but movement of the shaft  106  causes at least an attached component (e.g., the fastener  166  or button) to make direct contact with the plunge pin  112 . 
     At step  206  and in view of the force now applied to the plunge pin  112 , the biasing member  114  is compressed by a desired amount. At step  208 , the compression of the biasing member  114  causes the second retaining device  120  to be released from engagement with the driving system  102  since the transfer pins  116 , which are axially fixed, are now permitted to move radially inward corresponding to the tapered portion  160  of the plunge pin  112 . In short, axial movement of the shaft  106  results in axial movement of the plunge pin  112 , which in turn results in radial movement of the transfer pins  116  and circlip  120 . At step  210 , the shaft  106  and the inboard flexible joint  122  (i.e., the driven system  104 ) may be physically separated from the driving system  102 . 
       FIG. 6  shows another driven system  300  in the form of a drive axle system having an inboard flexible joint assembly  302  coupled to an outboard flexible joint assembly  304  through the axle shaft  306 . The driven system  300  is similar to the driven system  104  described above and includes some similar or identical components. For the purposes of brevity, such similar or identical components will not necessarily be described in detail herein and may not be provided reference numerals. 
     In the illustrated embodiment, both the inboard and outboard flexible joint assemblies  302 ,  304  take the form of universal joints. The shaft  306  includes a splined portion  308  coupled to a inner race  310  and movable along a shaft axis  312  relative to the inner race  310 . A plunge pin assembly  314  includes a plunge pin  316 , a biasing member  318 , a transfer pin  320 , a first retaining device  322  and a second retaining device  324 . 
     A plunge pin  316  includes an extended head portion  326  sized for controlling a distance  328  between the plunge pin  316  and a shaft end surface  330 . In the illustrated embodiment, the head portion  326  is an oval or elliptical shape, but other shapes may be utilized. The operation of the plunge pin assembly  314  is substantially the same as described above with regard to  FIG. 5  except that the end surface  330  of the shaft  306 , instead of a fastener, makes direct contact with the plunge pin  316 . 
     The plunge pin  316  is fit within the coupler shaft with close tolerances or seals to prevent oil leaking into the CV joint housing when the end of the coupler shaft is open to the internal space of the final drive as in the case of the front differential in the preferred embodiment. 
     While the preferred embodiments of the invention have been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiments. Instead, the invention should be determined entirely by reference to the claims that follow.