Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Plural circumferentially spaced elements
Reexamination Certificate
1998-04-28
2001-06-12
Kim, Harry C. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Plural circumferentially spaced elements
C192S043100, C192S069100
Reexamination Certificate
active
06244965
ABSTRACT:
TECHNICAL FIELD
The invention relates to torque transmitting couplings for accommodating torque transfer from a driving member to a driven member, but which will permit freewheeling overrunning motion of the driving and driven members upon a torque reversal.
BACKGROUND OF THE INVENTION
Overrunning coupling assemblies are used for transferring torque from a driving member to a driven member in a variety of structural environments. This permits the transfer of torque from a driving member to a driven member while permitting freewheeling motion of the driving member relative to the driven member when torque is interrupted. Such couplings often comprise an outer race concentrically disposed with respect to an inner race, the outer race having cammed surfaces that define a pocket in which coupling rollers are assembled.
A driving member is connected to one race, and a driven member is connected to the other race. During torque transfer from the driving member to the driven member, the rollers become locked with a camming action against the cam surfaces, thereby establishing a positive driving connection between the driving member and the driven member. When the torque is interrupted, the driven member may freewheel relative to the driving member as the rollers become unlocked from their respective cam surfaces.
Another common overrunning coupling includes inner and outer races wherein one race is connected to a driving member and the other race is connected to the driven member. Overrunning coupling sprags are disposed between the inner cylindrical surface of the outer race and the outer cylindrical surface of the inner race so that the sprags lock the races together as torque is delivered to the driven member. The sprags become unlocked with respect to the inner and outer race surfaces when torque transfer is interrupted.
Unlike overrunning roller clutches and overrunning sprag clutches commonly used in torque transfer mechanisms, the improved coupling of this invention comprises planar coupling plates situated in close juxtaposed relationship. The plates are mounted on a common axis of rotation. Each planar coupling plate has strut recesses. One of the coupling plates receives torque-transmitting struts, which are pivoted about the respective edges of the plate recesses. The opposite edge of each strut is adapted to be received in a cooperating recess formed in the companion coupling plate. Upon torque interruption, the struts will become disengaged from the driven coupling plate and will pivot about their respective pivot edges, thereby causing them to be substantially enclosed in the recesses of the driving coupling plate. When the struts are positioned in this fashion, free-wheeling motion of the coupling plates may take place, one with respect to the other.
Described in co-pending patent application Ser. 08/871,192, filed Jun. 9, 1997, now U.S. Pat. No. 5,918,715 entitled “Overrunning Planar Clutch Assembly”, is a planar coupling having struts and individual strut springs that normally urge the struts about the strut pivotal axis the recesses in the driven coupling plate. When the driving member transfers torque to the driven member in one direction, the struts will become locked in the recesses of the driven coupling plate. If the driven coupling plate overruns the driving coupling plate when torque transfer is interrupted, the struts will ratchet over the recesses of the driven plate.
BRIEF DESCRIPTION OF THE INVENTION
The improved planar coupling assembly of this invention controls the motion of the struts by preventing pivotal motion of the struts about their respective pivot axes when the coupling plates are in a free-wheeling mode. Provision is made, however, for allowing the struts to pivot about their respective pivotal axes so that the active edge of each strut may engage the recesses of the driven coupling plate during torque transfer from the driving member to the driven member. This control of the position of the struts is achieved in our improved design by a strut retainer plate, which is situated in the coupling assembly in coaxial disposition with respect to the driving member and the driven member.
The strut retainer plate includes angularly spaced apertures that allow the struts to pivot about their respective axes into engagement with the recesses of the driven plate when the strut retainer plate is in one axial position. When the strut retainer plate is shifted rotatably to another angular position relative to the driving plate, the recesses in the strut retainer plate will not be in full registry with the recesses of the driving plate. The strut retainer plate, when it is thus positioned, will prevent the struts in the recesses of the driving plate from moving about their respective pivotal axes. This eliminates the ratcheting condition described in the preceding discussion and substantially reduces the possibility of wear of the relatively movable coupling members. The planar coupling assembly is particularly adapted for high speed operating conditions and for operation under low volume lubricating oil operating conditions.
Any noise that would be associated with ratcheting of the struts over the recesses of the driven plate is eliminated in our improved coupling. Further, manufacture of our improved coupling does not require the precision machining operations that are required in the manufacture of conventional sprag couplings and roller couplings. Many of the components may be manufactured using powder metal casting and forming techniques.
According to a second embodiment of the invention, the strut retainer plate is designed with three operating states, each of which is characterized by a separate angular position of the strut retainer plate relative to the coupling driving plate.
When the strut retainer plate assumes a first position relative to the coupling driving plate, the struts are allowed to pivot about their respective pivotal edges, thereby allowing the struts to pass through the apertures in the strut retainer plate and enter a first series of recesses in the driven coupling plate when the strut retainer plate assumes a first operating position. This permits torque transfer in a direction from the driving member to the driven member.
The driving coupling plate for this second embodiment of the invention includes also a second series of recesses in which are positioned individual struts that are allowed to pivot about one edge in an angular direction opposite to the angular direction of the pivotal motion of struts in the first series of recesses. As in the case of the struts for the first series of recesses in the driving plate, the struts in the second series of recesses in the driving plate are allowed to pass through the apertures in the strut retainer plate when the strut retainer plate assumes a second operating position. This will permit torque to be transferred in the opposite direction between the driving and driven members as the struts in the second series of recesses of the driving plate engage one edge of the recesses in the driven coupling plate.
When the strut retainer plate assumes a third operating position intermediate the first and second positions, the struts of each set are held within their respective recesses, thereby permitting free-wheeling motion of the driving plate and the driven plate, one with respect to the other.
When the strut retainer plate is in the first position, as discussed above, the strut retainer plate will hold the struts of the second series of recesses in their respective recesses and pivotal motion of those struts will be prevented.
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Harrison Sharon
Klecker Brian D.
Brooks & Kushman P.C.
Kim Harry C.
Means Industries Inc.
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