Patent Application
20080056634
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Turning now to the drawings,
The external flange 22 has a stepped inside diameter 42 that creates an internal load shoulder 44. The load shoulder 44 and threaded holes 46 in the external flange form a jack screw mechanism that is used to disengage the mounting system as discussed in more detail below with reference to
Drive threads 48 are located on the inside diameter 42 of the external flange 26 and are used to urge the sleeve 50 to the initial position. As discussed above, the initial position is the point where tolerances and initial clearances between the mating parts have been removed. The sleeve has a tapered outside diameter 52 that engages the tapered insider diameter 16 of the bearing assembly 12. The outer portion of the sleeve transitions from the tapered outside diameter to a uniform outside diameter 54 near the front face 56 of the sleeve. It should be noted that the present system may be employed with components that are differently configured, particularly insomuch as the engaging tapers are concerned. For example, to avoid tapering the bearing ring itself, another sleeve may be interposed in the assembly that has a surface interfacing with the inner diameter of the inner bearing ring, and a tapered inner surface that contacts the tapered outside diameter of sleeve 50.
The front face 56 of the sleeve has a plurality of recesses 58 which form a front load surface 60. These recesses align with the drive threads 48 in the external flange 22. A plurality of screws 62 engage the drive threads 48 and recesses 58. The screws 62 further engage the sleeve 50 via the front load surface 60 formed by the recesses. This allows the tapered sleeve 50 to be driven into the bearing kit 10 thereby initially securing the bearing assembly to the shaft. The tapered sleeve has a uniform inside diameter 66 and an axial split 68 allowing it to clamp down on a circular shaft when the tapered diameters are driven together. The transition from the tapered diameter 52 to the uniform diameter 54 forms an extraction load face 70. This face is used to disassemble the parts via the jack screw mechanism as described below.
The tapered sleeve 50 is then pressed into engagement between the inner ring 78 and the shaft by engaging the screws 62 into the drive threads 48 located in the external flange 22. Sets of drive threads are aligned with respective recesses located in the sleeve and allow the screws to completely engage the drive threads. A torque, as indicated by reference numeral 86, is applied to the screws, forcing them against the front load surface 60 and thereby axially loading the sleeve, as indicated by reference numeral 90, and urging it towards the bearing assembly. This drives the tapered diameters together and results in an expansion/compression force, represented by reference numeral 92, between the parts. Thus, these screws are used to drive the sleeve to the zero reference point or initial position, which as discussed above, is the position where the tolerances and initial clearance between the mating parts has been removed.
The user determines this initial position by monitoring the torque input, as indicated by reference numeral 86, into the screw and stopping once an empirically determined torque value has been reached. This may be done via a conventional torque wrench, and the initial position torque will typically be indicated by the manufacturer of the system, based upon the particular size and configuration of the bearing and other components. Those skilled in the art will appreciate that this point load drive system reduces frictional losses in the drive mechanism and allows the user to accurately determine and reliable quantify the initial position by monitoring the torque input to the screws. In other words, the invention reduces the uncertainty in the torque measurement by minimizing the impact of the variance in this resistance component. Furthermore, the invention does not require the user to overcome an excessive amount of frictional resistance, thereby making it easier to install the system. Also, a standard torque wrench is the only special tooling required, thus eliminating the need for other tooling or custom fixturing.
As discussed above, determining the initial position is useful because it represents the point where all of the tolerances and initial clearance between mating parts has been removed. Once this initial position has been determined, the user only needs to drive the sleeve a predetermined distance to properly reduce the internal clearance of the bearing, labeled “x”, or otherwise fully engage the sleeve between the bearing and the shaft. One of the advantages of the present invention is that the width 94 of the removable spacer, labeled “y”, is equal to the axial displacement required to drive the sleeve from the initial position to the proper final position. Thus, to easily remove the amount of internal clearance, the user only needs to remove the spacer 42 and apply a torque, represented by numeral 96, to the fastener 26, thereby shouldering the external flange against the internal flange. In doing this, the predetermined displacement “y” is directly transferred to the sleeve via the drive screw interaction described above. Thus, the exact amount of radially expansion required to reduce the internal clearance of the bearing, or the tight engagement of the sleeve between the bearing and shaft is automatically and precisely set by simply mating the two flanges.
The screws 62 may remain in place during operation and help to ensure the sleeve does not disengage the bearing assembly by keeping a constant load on the front load surface. The screws also serve to key the parts together by rotatably locking the internal flange 14, external flange 26, tapered sleeve 50, and inner race 78. This prevents any relative motion between these parts that could otherwise generate frictional heat and lead to eventual failure or unscheduled maintenance of the system.
Finally, as mentioned throughout the present discussion, the present mounting system is not limited to bearing assemblies and may be used to mount other mechanical elements to a shaft. For example, the system may serve to mount mechanical couplings used to couple one shaft to another. To complete this coupling a mechanical element (typically a coupling “half”) is directly mounted to the shaft. The present system may be used to mount this type of element, and many others, directly to a shaft offering all of the same benefits and advantages described above.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
