192 clutches and power-stop control – Clutches – Automatic
Reexamination Certificate
1999-11-30
2001-02-13
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Clutches
Automatic
C192S069100, C192S113320
Reexamination Certificate
active
06186299
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an overrunning coupling assembly including enlarged strut pockets so that the struts are tangentially movable to reduce the moment arm of the spring acting on each strut so that the forces of flowing lubricant are sufficient to hold each strut in its disengaged position to prevent the strut from slapping against the notch recesses as the notch plate and pocket plate are respectively counterrotated.
BACKGROUND ART
The invention is adapted especially for use in stator assemblies for torque converter transmissions in an automotive vehicle driveline. The invention may be used also in other applications, however, such as torque transfer drives and chain drives that require an overrunning coupling in a torque flow path.
Torque converter transmissions include a stator assembly having a stator hub secured to a stationary sleeve shaft and stator blades situated between a toroidal flow exit section of a hydrokinetic turbine and the toroidal flow entrance section of a hydrokinetic impeller. The blades of the stator change the direction of the tangential component of the toroidal flow velocity vector at the turbine exit section prior to entry of the toroidal flow to the impeller entrance section. This permits multiplication of torque as the hydrokinetic converter delivers engine power to a power input element of a multiple ratio gearing in the transmission mechanism.
It is known practice in the automotive transmission art to design the stator assembly of a hydrokinetic torque converter transmission with a stator hub that is adapted to receive an overrunning coupling having an outer race and an inner race, the inner race being splined to a stationary sleeve shaft and the outer race being carried by the bladed section of the stator assembly. The outer race typically would be cammed to provide a plurality of cam surfaces that are engageable by overrunning coupling rollers. The overrunning coupling permits reaction torque delivery from the stator blades to the stationary sleeve shaft when the torque converter is in a torque multiplication mode. The rollers and the cam surfaces with which they interact will permit free-wheeling motion of the bladed section of the converter when the torque converter is in a coupling mode.
The outer race of a conventional overrunning stator coupling is keyed or splined in a central opening in the stator hub. It is held in place by snap rings located in snap ring grooves machined in the stator hub.
My prior U.S. Pat. No. 5,597,057, which is owned by the assignee of the present invention, and which is hereby incorporated by reference in its entirety, provides an improved overrunning coupling assembly having an annular coupling pocket plate with strut pockets disposed therein and a notch plate disposed in face-to-face relationship with the pocket plate. The notch plate includes notch recesses at angularly spaced positions about the axis and disposed in juxtaposed relationship with respect to the strut pockets. Torque transmitting struts are positioned in the strut pockets and spring-biased for engagement with the notch recesses.
Further improvements in overrunning coupling designs are desirable, particularly those improvements which reduce manufacturing costs and eliminate wear issues. For example, one potential problem associated with the above-referenced overrunning coupling design is that a certain amount of noise may be generated by the struts “slapping” or rattling against the notch recesses of the notch plate. Also, wear of the strut on top and edge surfaces during overrun may be a concern. It is also desirable to reduce the need for constant and controlled lubrication.
DISCLOSURE OF INVENTION
The present invention improves upon prior overrunning coupling designs by providing enlarged strut pockets which allow tangential sliding movement of the struts to decrease the length of a moment arm about which a spring acts upon each strut, thereby enabling the forces of flowing lubricant or grease to hold the strut in a position parallel to a bottom surface of each strut pocket to prevent slapping of the struts against the notch recesses and to reduce wear issues and reduce lubrication requirements.
More specifically, the present invention provides an overrunning coupling assembly including a notch plate and an annular coupling pocket plate positioned in face-to-face relationship with respect to each other along a common axis. The pocket plate has strut pockets disposed at angularly spaced positions about the axis. The notch plate has notch recesses at angularly spaced positions about the common axis and positioned in juxtaposed relationship with respect to the strut pockets. Torque-transmitting struts are positioned in each strut pocket. Each strut has first and second ears at one edge thereof for enabling pivotal motion of the struts about an ear axis intersecting the ears. The opposite edge of each strut is movable between disengaged and engaged positions with respect to one of the notch recesses, whereby one-way torque transfer may occur between the plates. A lubricant flows between the notch plate and pocket plate. A spring is positioned in each strut pocket and biases the respective strut toward the notch plate. Each spring engages the respective strut intermediate the ear axis and the opposite edge. Each strut pocket provides sufficient clearance forward of the respective opposite edge of the strut to allow forward sliding movement of the respective strut during overrunning to cause the engagement of the respective spring and strut to occur nearer the ear axis, thereby reducing the length of a moment arm about which the spring acts upon the strut which enables frictional forces of the flowing lubricant to hold the strut in its flat, disengaged position to prevent the strut from slapping against the notch recesses as the notch plate and pocket plate are respectively counterrotated.
The strut pocket may be sufficiently enlarged to allow strut movement to a position in which the spring force is fully reacted by the ears, or to a position in which the spring is spaced only slightly from the ear axis such that the flowing lubricant holds the strut in the disengaged position. Alternatively, the strut pockets may be sufficiently enlarged to allow sliding movement of each strut to a position in which a forward corner of each strut engages the outer circumferential rail of the notch plate to prevent slapping.
The invention described herein eliminates the noise of struts slapping against the notch plate and eliminates wear issues of the strut top and edge surfaces during overrun. It also eliminates wear issues of the spring against the bottom of the strut and reduces lubrication requirements. Additionally, it eliminates the requirement of a weir which was previously used to seal oil to maintain high oil pressure because the invention does not require a high head pressure of oil within the coupling assembly.
The invention also reduces the need to retain a high volume of oil for hydraulic dampening and reduces the requirement to balance spring force with engagement dynamics, i.e., proper positioning of the spring to overcome centrifugal friction. The invention is a no cost add to current designs, and ultimately should reduce cost. It allows oil to freely flow radially through the pocket plate as needed for lubrication of the friction plates due to decreased oil requirements. Also, the invention allows the use of different materials and different heat treatment for the struts because the wear is significantly reduced.
Accordingly, an object of the present invention is to provide an improved overrunning coupling assembly in which the noise of struts slapping against the notch plate is eliminated.
A further object of the present invention is to provide an improved overrunning coupling assembly in which fluid lubrication volume requirements are significantly reduced and wear issues are reduced for the strut top and edge surfaces, as well as spring wear against the bottom of the strut.
A further object of the present invention
Brooks & Kushman P.C.
Lorence Richard M.
Means Industries Inc.
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