Quick disconnect for a drive unit

Abstract

A drive unit disconnect mechanism is operable to transmit or disconnect power from a vehicle power source to a driven unit, and can be disengaged by multiple methods depending on how much force is required to separate the internal components of the mechanism. In a first, relatively quicker method, a handle is pulled axially away from the hub to withdraw and internal gear from splined engagement with a corresponding driven gear. In a second, relatively slower method, the handle is rotated to threadably withdraw the entire disconnect mechanism from the hub, which in turn withdraws the internal gear from splined engagement with the driven gear. The quicker method is desirable in most instances, but the slower method allows disconnection of the driven unit from the vehicle power source when gear pressure prevents or impedes the quicker method.

What is claimed is: 
     
         1 . A disconnect mechanism having an engaged configuration and a disengaged configuration, the mechanism comprising:
 a hub attachable to a driven unit, said hub having an inward side and an opposing, user-accessible outward side, said hub having a threaded bore extending from said inward side to said outward side;   an outer shaft having a bore extending axially therethrough, said outer shaft defining a threaded engagement with said bore of said hub to axially move said outer shaft between an outer-shaft seated position in which said outer shaft is relatively inwardly disposed with respect to said hub, and an outer-shaft withdrawn position in which said outer shaft is relatively outwardly disposed with respect to said hub;   an inner shaft received within said outer shaft, said inner shaft axially movable with respect to said outer shaft between an inner-shaft seated position in which said inner shaft is relatively inwardly disposed with respect to said outer shaft, and an inner-shaft withdrawn position in which said inner shaft is relatively outwardly disposed with respect to said outer shaft; and   a coupling gear axially fixed to said inner shaft, said coupling gear defining:
 an engaged position corresponding to the engaged configuration of the disconnect mechanism, said coupling gear in said engaged position when said outer shaft is in said outer-shaft seated position and said inner shaft is in said inner-shaft seated position, and 
 a disengaged position corresponding to the disengaged configuration of the disconnect mechanism, said coupling gear in said disengaged position when said outer shaft is in said outer-shaft withdrawn position or said inner shaft is in said inner-shaft withdrawn position. 
   
     
     
         2 . The disconnect mechanism of  claim 1 , further comprising a handle connected to said outer shaft, said handle cooperating with a thread pitch of said threaded engagement to create a mechanical advantage when said outer shaft is threadably toggled between said outer-shaft seated position and said outer-shaft withdrawn position, wherein movement of said handle by a movement distance causes an axial movement of said coupling gear by less than the movement distance. 
     
     
         3 . The disconnect mechanism of  claim 1 , further comprising a handle connected to said inner shaft, wherein movement of said handle by a movement distance results in axial movement of said coupling gear by the movement distance. 
     
     
         4 . The disconnect mechanism of  claim 1 , in combination with a wheel drive unit including a powered input gear and a driven gear,
 said hub operably connected to said driven gear when said coupling gear is in said engaged position, such that power from said powered input gear is transferred to said hub, and   said hub operably disconnected from said driven gear when said coupling gear is in said disengaged position, such that said hub is independently rotatable with respect to said powered input gear.   
     
     
         5 . The combination of  claim 4 , wherein said wheel drive unit comprises a planetary transmission assembly. 
     
     
         6 . The disconnect mechanism of  claim 1 , further comprising a spring, said spring urging said inner shaft toward said inner-shaft seated position. 
     
     
         7 . The disconnect mechanism of  claim 1 , wherein:
 said outer shaft comprises a stepped portion defining a shoulder formed on said outer shaft; and   said bore of said hub comprises a shoulder within said bore, said shoulder of said hub cooperating with said shoulder of said outer shaft to limit inward axial movement of said outer shaft, thereby defining said outer-shaft seated position.   
     
     
         8 . The disconnect mechanism of  claim 1 , wherein:
 said coupling gear defines an inner face;   said hub defines an inner shoulder disposed within said bore of said hub;   said inner face of said coupling gear impinges on said inner shoulder of said hub when said inner shaft is in said inner-shaft withdrawn position to prevent further outward axial travel of said inner shaft;   said inner face of said coupling gear impinges on said inner shoulder of said hub when said outer shaft is in said outer-shaft withdrawn position to prevent further outward axial travel of said inner shaft;   whereby said inner-shaft withdrawn position cannot exist concurrently with said outer-shaft withdrawn position.   
     
     
         9 . A disconnect mechanism for selectively disconnecting a hub from a power source, the mechanism comprising:
 a hub attachable to a driven unit, said hub having an inward side and an opposing, user-accessible outward side, said hub having a threaded bore extending from said inward side to said outward side;   a coupling gear axially movable with respect to said hub between an engaged position in which said coupling gear extends relatively further outwardly and a disengaged position in which said coupling gear extends relatively further inwardly;   means for axially toggling said coupling gear between said engaged position and said disengaged position by direct axial displacement, wherein said coupling gear is axially displaced with no mechanical advantage; and   means for threadably toggling said coupling gear between said engaged position and said disengaged position by threaded rotational displacement, wherein said coupling gear is axially displaced with a mechanical advantage.   
     
     
         10 . The disconnect mechanism of  claim 9 , wherein said coupling gear includes outer splines and said hub includes a first set of inner splines mated with said outer splines of said coupling gear, in combination with a means for transmitting power from the power source to said coupling gear including:
 an input gear adapted to couple with a motor output shaft;   an output gear having a second set of inner splines, said outer splines of said coupling gear mated with both of said first set of inner splines and said second set of inner splines when said coupling gear is in said engaged position, said outer splines mated only with said first set of inner splines when said coupling gear is in said disengaged position.   
     
     
         11 . The disconnect mechanism of  claim 10 , wherein said means for transmitting power comprises gear reduction means for reducing a rotational speed of said output gear with respect to said input gear. 
     
     
         12 . The disconnect mechanism of  claim 9 , further comprising displacement means for directly axially displacing said means for axially toggling, said displacement means also for rotating said means for threadably toggling. 
     
     
         13 . The disconnect mechanism of  claim 9 , further comprising biasing means for urging said coupling gear toward said engaged position. 
     
     
         14 . The disconnect mechanism of  claim 9 , further comprising means for limiting a range of axial travel of said coupling gear. 
     
     
         15 . A method of disengaging a driven unit from a vehicle power source, the method comprising:
 receiving a hub;   receiving a driven gear;   receiving a disconnect mechanism operable to selectively engage the hub with the driven gear via a coupling gear, the disconnect mechanism defining:
 an engaged configuration in which the hub is operably engaged with the driven gear; 
 a handle-disengaged configuration in which the hub is disengaged from the driven gear by direct axial displacement of the coupling gear; and 
 a screw-disengaged configuration in which the hub is disengaged from the driven gear by threaded disengagement of the disconnect mechanism from the hub; and 
   with the disconnect mechanism in the engaged configuration, assessing whether the coupling gear and driven gear are under sufficient pressure to prevent disengagement of the hub from the driven gear by placing the disconnect mechanism into the handle-disengaged configuration.   
     
     
         16 . The method of  claim 15 , further comprising, if the step of assessing results in an assessment that the coupling gear and driven gear are under the sufficient pressure:
 rotating a handle connected to the disconnect mechanism in a first rotational direction, said step of rotating the handle placing the disconnect mechanism in the screw-disengaged configuration, said step of rotating a handle including applying a mechanical advantage to force the coupling gear out of engagement with the driven gear.   
     
     
         17 . The method of  claim 16 , wherein said disconnect mechanism further includes a spring creating a biasing force urging the disconnect mechanism toward the engaged configuration, the method further comprising:
 placing the disconnect mechanism into a waiting-to-engage configuration by rotating the handle in a second rotational direction opposite the first rotational direction, in which the waiting-to-engage configuration biases the coupling gear toward the driven gear, and in which the disconnect mechanism will automatically enter the engaged configuration upon alignment of mating splines on the coupling gear and driven gear.   
     
     
         18 . The method of  claim 15 , further comprising, if the step of assessing results in an assessment that the coupling gear and driven gear are not under the sufficient pressure:
 pulling a handle connected to the disconnect mechanism to place the disconnect mechanism in the handle-disengaged configuration, said step of pulling a handle including directly applying force to the coupling gear to dislodge the coupling gear from engagement with the driven gear.   
     
     
         19 . The method of  claim 18 , wherein said disconnect mechanism further includes a spring creating a biasing force urging the disconnect mechanism toward the engaged configuration, said step of pulling a handle further comprising pulling the handle against the biasing force to counteract the biasing force, the method further comprising:
 placing the disconnect mechanism into a waiting-to-engage configuration by releasing the handle such that the biasing force of the spring is no longer counteracted, in which the waiting-to-engage configuration biases the coupling gear toward the driven gear, and in which the disconnect mechanism will automatically enter the engaged configuration upon alignment of mating splines on the coupling gear and driven gear.   
     
     
         20 . The method of  claim 15 , wherein the driven gear forms a part of a wheel drive unit.