Seal for Installing Seal Over Splined Shaft

1. Field of the Invention

This invention relates to seals and to the installation of seals onto a shaft.

2. Description of the Prior Art

In the art of sealing the spline area of truck prop. shafts, prior art designs have used a cork or felt split gasket compressed into a screw-on cap. This prior art technique is expensive, creates an assembly problem, and is ineffective in excluding contaminants. Elastomeric seals have not been used previously in this application because the seal must first pass over a spline which is approximately 0.4 inch larger in diameter than the surface upon which the sealing lip rides. The other end of such a shaft has a yoke with an O.D. larger than that of the splined portion of the shaft, as will be understood by those skilled in the art. Other seal applications such as the power take-off on agricultural equipment present similar problems.

It is an object of the present invention to overcome such problems in the prior art and to provide relatively inexpensive, easy to install seals which positively exclude contaminants.

The seal according to one preferred embodiment of the present invention is a molded elastomeric seal having an annular mounting portion, a sealing lip portion, and an elongated portion connecting the mounting and sealing lip portions. During installation of the seal on a shaft having a first portion that can damage the sealing lip and a second portion on which the sealing lip is to ride, the sealing lip portion is reversed, that is, it is folded under the mounting portion, such that the O.D. surface of the sealing lip portion rides on the first portion of the shaft maintaining the sealing lip out of contact with the shaft to protect it from damage. After the shaft has been inserted through the seal, the sealing lip portion is returned to its normal, sealing configuration in contact with the second portion of the shaft. In other embodiments, the sealing lip portion is moved to a non-sealing configuration during installation over the first shaft portion such as being reversed as mentioned above or by being folded up and locked on top of the mounting portion.

The present invention will be more fully understood by reference to the following detailed description thereof, when read in conjunction with the attached drawings, wherein like reference numerals refer to like elements and wherein:

FIGS. 1-3 are each a partial cross-sectional view through a seal of the present invention, with FIGS. 1 and 3 illustrating two different embodiments of the invention;

FIGS. 4 and 5 are each a partial cross-sectional view through another seal of the present invention; and

FIGS. 6 and 7 are each a cross-sectional view through yet another seal of the present invention.

With reference not to the drawings, FIGS. 1-3 show a seal 10 according to the present invention for installation on a shaft 12 having a first splined portion 14 and a second, smooth portion 16. The splined portion 14 has an O.D. approximately 0.4 inch greater than the O.D. of the smooth portion 16. FIG. 3 shows the seal 10 in its preferred non-sealing configuration as it is being installed over the splined portion 14 (moved to the right in the FIGS. relative to the shaft 12). FIG. 1 shows the seal 10 in another non-sealing configuration during installation, and FIG. 2 shows the seal 10 in its normal, sealing configuration on the smooth portion 16 of the shaft 12.

The seal 10 is preferably molded from an elastomeric material and includes a mounting portion 20, an elongated (preferably a hollow frusto-conical or tapered) portion 22 and a sealing lip portion 24. The mounting portion preferably includes an annular metal shell 26 on the O.D. thereof. The I.D. of the mounting portion preferably includes a plurality of annular grooves and ridges 28 and 30, respectively. The elongated portion 22 includes an intermediate, relatively short length portion 32 of reduced thickness smaller than that of the adjacent sections of the elongated portion 22, and an annular, radially inwardly extending enlargement 33, for a purpose to be explained below. The sealing lip portion 24 includes a sealing lip 34 and an annular groove 36 on the O.D. surface thereof.

FIG. 3 shows the preferred embodiment of the present invention wherein the sealing lip portion 24 is moved to a non-sealing configuration by being reversed from its normal sealing position shown in FIG. 2. That is, it is folded under and extends from the mounting portion 20 in the opposite direction from that when the sealing lip portion is in its normal sealing configuration. In the non-sealing configuration shown in FIG. 3, the sealing lip 34 is held away from and out of contact with the first, splined portion 14 of the shaft 12 to protect the sealing lip 34 from damage during installation. During installation over the first portion 14, the O.D. surface 38 of an enlargement 40 on the O.D. of the sealing lip portion 24 rides directly on the surface of the first, splined portion 14 of the shaft 12. After the seal 10 has passed over the first, splined portion 14 of the shaft, the sealing lip portion 24 is then moved back from its reversed position shown in FIG. 3 to its normal sealing configuration shown in FIG. 2. The mounting portion 20 is then attached to a housing 44 as shown in FIG. 2.

FIG. 1 shows another non-sealing configuration. In this embodiment the sealing lip portion 24 is slightly stretched and is folded up on top of, and is locked onto the distal end 42 of the mounting portion 20 with the distal end 42 being received within the groove 36 of the sealing lip portion, during installation. After the first splined portion 14 of the shaft 12 has been inserted through the seal 10 (or the seal moved over the first splined portion), the sealing lip portion 24 is then unlocked from the folded, non-sealing configuration and returned to the normal, sealing configuration shown in FIG. 2. The seal 10 is then press-fitted onto the O.D. of a housing 44 (such as the yoke of the adjacent prop. shaft) as shown.

In the embodiment of FIGS. 1-3 the housing 44, the seal 10 and the shaft 12 rotate together, however, the seal 10 and the method of installation of this invention can alternatively be used in applications where the housing 44 and the seal 10 rotate relative to the shaft 12 (that is, the housing 44 and seal 10 are stationary and the shaft 12 rotates or vice versa). The annular enlargement 33 is an increased mass of elastomeric material that helps to hold the sealing lip 34 on the shaft 12 during rotation and by being located approximately radially in-line with the portion 32 of reduced thickness the centrifugal force on the enlargement 33 during rotation of the seal 10 will not tend to lift the sealing lip portion 24 off of the shaft 12.

Referring now to the embodiment of FIGS. 4 and 5, this embodiment comprises a seal 50 which is similar to the seal 10 of FIGS. 1-3 except that it does not include the same elongated portion 22 and it is thus useful in narrow cross-section applications. The seal 50 includes a mounting portion 52 and a sealing lip portion 54. The mounting portion includes a metal reinforcing shell 56 having a cylindrical portion 58 and a radially outwardly extending member 60 having a distal end 62. The sealing lip portion 54 includes a sealing lip 64 and a groove 66 on the O.D. surface thereof. The normal sealing configuration of the seal 50 is shown in FIG. 4. FIG. 5 shows a non-sealing configuration of the seal 50 with the sealing lip portion 54 stretched and folded up on top of the mounting portion 52 and locked thereto with the radially outwardly extending member 60 engaged in the groove 66. The operation of the seal of this embodiment of the present invention is similar to that of the seal as shown in FIGS. 1-3.

FIGS. 6 and 7 show another embodiment of the present invention of a seal 70 comprising a mounting portion 72 and a sealing lip portion 74. The mounting portion 72 includes a metal reinforcing shell 76 and a plurality of grooves and ridges on the I.D. surface 78 thereof. The sealing lip portion 74 includes a sealing lip 80 and an O.D. surface 82. The seal 70 is shown in its normal sealing configuration in FIG. 6 and FIG. 7 shows the sealing lip portion in its reversed, non-sealing configuration during installation on the first, splined portion 14 of the shaft 12. In this non-sealing configuration, the sealing lip 80 is held away from and out of contact with the surface of the shaft portion 14 to protect it from damage, by having the O.D. surface 82 of the sealing lip portion 74 ride directly on and in contact with the surface of the first splined portion 14 of the shaft 12. After the seal 70 has passed over the first splined portion 14 of the shaft 12 and is over the second portion 16, the reversed or non-sealing configuration shown in FIG. 7 is changed by moving or folding (for example, by moving the seal 70 to the left with respect to the shaft 12) the sealing lip portion 74 to its normal sealing configuration shown in FIG. 6. The mounting portion 72 is then attached to a housing 44. The end wall 84 of the sealing lip portion 74 is not necessarily perpendicular to the length of the sealing lip portion but may be at an angle thereto as shown in FIG. 6.

The seals of the present invention are relatively inexpensive, are easy to install, and positively exclude contaminants from the application. By moving the sealing lip out of contact with the first portion 14 during installation, damage to the sealing lip is minimized or eliminated.

While the various seal embodiments and applications including the preferred embodiment and application, have been described above, other seal structures and methods and other seal applications can be used. For example, the seal and method can be used in other applications than with truck prop. shafts and slip joint prop. shafts, such as in the power take off of agricultural equipment and in any application where the seal must pass over a first portion of a shaft that could damage the sealing lip. The first portion need not be of larger diameter and need not be a splined shaft. Other ways of moving the sealing lip portion away from the first portion of the shaft can be used. The metal reinforcing shell is not essential. The press-fit surface of the mounting portion of the seal can be on the O.D. surface thereof instead of on the I.D. as shown and other ways of attaching the mounting portion to a housing can be used. The slight stretching required of the seal in certain of the embodiments described above is not so great as to require any unusual degree of elasticity in the elastomer; that is, standard elastomeric materials can be used. Further, other materials than elastomers, such as leather and PTFE can be used in certain embodiments. The term "tapered" as used herein means generally tapered, and includes a stepped construction as well as a smoothly tapered elongated portion. In all of the above embodiments, the sealing lip portion is movable to a non-sealing configuration in which the sealing lip is out of contact with the shaft and the seal includes means for holding the sealing lip out of contact with the shaft in the non-sealing configuration. Such means include, for example, the means for locking the sealing lip portion up on top of the mounting portion as shown in FIGS. 1 and 5, and the means such as the O.D. surfaces 38 and 82 in FIGS. 3 and 7.

The invention has been described in detail with particular reference to the preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.