Patent Application
20120076576
This invention relates to retaining rings for axially retaining a first member with respect to a second member.
Retaining rings are employed to retain one member with respect to another member in an axial direction. For example, in transmissions having clutches and planetary gearsets arranged coaxially along a shaft, retaining rings may be set in grooves formed in the shaft to limit axial movement of the clutch elements and planetary gear members. Retaining rings include internal and external snap rings. Typically, retaining rings are installed at the end of the part chain. In some instances, due to functional or packaging requirements, it is not possible to place the ring at the end of the part chain. In such situations, a “trapped” snap ring may be employed in a ring groove located in the center of the component being retained.
A retaining ring for axially retaining a first member with respect to a second member is provided. The first member has an outer surface characterized by a first portion and a second portion spaced axially from the first portion. The first portion has a first diameter, and the second portion has a second diameter greater than the first diameter. The second member has an inner surface characterized by a third portion and a fourth portion axially spaced from the third portion. The third portion has a third diameter, and the fourth portion has a fourth diameter greater than the third diameter. The retaining ring comprises a member having a generally annular shape and characterized by an inner surface and an outer surface. The inner surface is characterized by an inner surface minor diameter that is less than or equal to the first diameter, and the outer surface is characterized by an outer surface major diameter that is greater than or equal to the fourth diameter.
The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.
Referring to
The first portion 34 is characterized by a first diameter, and the second portion 38, which is axially spaced from the first portion 34, is characterized by a second diameter that is greater than the first diameter. In the embodiment depicted, the second portion 38 defines a first plurality of splines 50 that extend radially outward from outer surface 30, and which provide the second portion 38 with a greater diameter than the first portion 34. The splines 50 are evenly spaced around the circumference of the first member 14. The first portion 34 is a groove that extends through each of the splines 50 around the circumference of the first member 14.
The third portion 42 is characterized by a third diameter, and the fourth portion 46, which is axially spaced from the third portion 42, has a fourth diameter greater than the third diameter. In the embodiment depicted, the third portion defines a second plurality of splines 54 that extend radially inward from the inner surface 40, and which provide the third portion 42 with a diameter less than the diameter of the fourth portion 46. When the first member 14 and the second member 18 are installed within the transmission, the first plurality of splines 50 are meshingly engaged with the second plurality of splines 54 to prevent rotation of the first member 14 with respect to the second member about axis A, i.e., to transmit torque from the second member 18 to the first member 14. That is, each of splines 50 is disposed between a respective two splines 54. The fourth portion 46 is also axially aligned with the first portion 34. The retaining ring 10 is disposed between the fourth portion 46 and the first portion 34.
Referring to
The outer surface 66 is characterized by a plurality of alternating crests, or peaks 78, and valleys 82, such that the outer surface 66 is characterized by alternating segments that are concave and convex. Concave segments of surface 66 extend between peaks 78, and convex segments of surface 66 extend between valleys 82. The outer surface 66 is characterized by an outer surface minor diameter and an outer surface major diameter. As used herein, the outer surface minor diameter is the diameter of an imaginary cylinder that bounds or just touches the valleys 82, and the outer surface major diameter is the diameter of an imaginary cylinder that bounds or just touches the peaks 78. The outer surface major diameter is less than or equal to the fourth diameter, i.e. the diameter of the fourth portion 46. Accordingly, as shown in
The cross-sectional shape and dimensions of member 58 is substantially constant along the length of the member 58, and thus peaks 70 in the inner surface 62 are directly radially opposite valleys 82 in the outer surface 66. Similarly, valleys 74 in the inner surface 62 are directly radially opposite peaks 78 in the outer surface 66. As best seen in
Referring specifically to
Referring again to
More specifically, and with reference to
Surface 126 of splines 54, opposite surface 122, acts on the ring 10 to retain the ring, and therefore the first member 14, axially with respect to the second member 18. Surface 126 is axially inclined like surface 122, but at a steeper angle. Accordingly, removal of the first member 14 from the second member requires a larger force than installation. The installation force is determined by the angle of surface 122 and the radial stiffness of the ring 10. The removal force is determined by the angle of surface 126 and the stiffness of the ring 10. Accordingly, installation and removal forces can be varied by varying the angles of surfaces 122, 126, the material of the ring 10, the cross-sectional shape of the ring 10, etc.
The member 58 in the embodiment depicted is characterized by alternating segments that are generally arc-shaped to provide the ring 10 with the variable effective diameter; however, other segment shapes may be employed within the scope of the claimed invention. The member 58 in the embodiment depicted is characterized by a rectangular cross-section; however, other cross-sectional shapes may be employed within the scope of the claimed invention, such as square, circular, oval, etc. The retaining ring 10 and first and second members 14, 18 are shown in the context of a vehicle transmission 22; however, the retaining ring 10 and first and second members 14, 18 may be employed in any system, device, etc. within the scope of the claimed invention.
The retaining ring 10 retains the axial packaging advantages of a conventional trapped ring design while improving radial packaging and minimizing assembly issues by utilizing the characteristics of both a snap ring and flat spring. The ring 10 will not sag in the groove 34, eliminating the need to align the ring 10 prior to installing the second member 18, thereby improving assembly. Also, the groove 34 depth needs only to be deep enough to accommodate the thin section of the ring 10 during assembly. Depending upon design requirements, the angle of the rear face of the second member may be altered to facilitate disassembly over thrust load retention or vise versa.
The ring 10 may be characterized by very low radial compression loads, resulting in low installation force. The ring 10 does not require special tools either to assemble or disassemble. Adequate retention loads maintained by a combination of axial stiffness (cross section) and angle of axial mating reaction surfaces. Disassembly forces are reasonable and not excessive, requiring no special tools to disengage. The ring 10 resists centrifugal loading that can cause radial dislocation from retention groove 34, due to radial constraints at the inner diameter and the outer diameter. The ring 10 is less prone to “bellevilling” due to its inherent axial rigidity (“bellevilling” is a term used to describe the tendency of conventional snap rings to go from a flat to conical shape when under high axial loads). The ring 10 does not require deep radial grooves for adequate retention and axial support, thereby enabling reduced radial cross sections (and thereby mass, inertia, and cost) of the mating components being retained.
While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.
