Limited slip differential with adjustable preload

[0002] The present invention relates to a differential assembly and more particularly to a differential assembly having a limited slip device with adjustable pre-load.

[0003] Differential assemblies having a limited slip device are known in the art. FIG. 1 depicts a differential assembly having a limited slip device according to the prior art. Differential pinions 5 and side gears 7 are disposed within a differential case 6. A multiple-disc clutch pack 4 is disposed between one or each of the side gears 7 and the differential case 6. The differential case 6 may have axial grooves or splines to prevent rotation and allow axial displacement of friction discs of the clutch pack 4. Similarly clutch plates are splined onto the side gears 7 and interposed between the friction discs. A spring is normally disposed between the side gears 7 to urge the side gears 7 apart and cause frictional engagement in the clutch pack. However, a Belleville spring 8 may be disposed between the clutch pack 4 and either the side gear 7 or differential case 6. The friction between the friction discs and clutch plates limits the amount that the side gears 5 may slip relative to the differential case 6. However, the prior art assemblies do not facilitate selective adjustment of the clutch pack 4 preload. Moreover, the prior art fails to provide a means to adjust the clutch pack 4 preload after the differential is assembled and provide easy readjustment after a portion of its service life has expired or the ability to easily externally adjust the clutch pack 4 preload from the differential case 6.

[0004] The present invention is directed to a differential assembly having a limited slip device with adjustable preload. The differential assembly includes a differential case with pinion and side gears disposed therein. The clutch pack is disposed between at least one of the side gears and the differential case to retard relative rotation there between. An adjustment collar is disposed between the clutch pack and the differential case to adjust the preload of the clutch pack. Elongated slots are formed through the differential case to provide external access to spanner slots formed in the adjustment collar. A tool may be inserted through the elongated slots to engage the spanner slots and selectively rotate the adjustment collar to adjust the pre-load of the clutch pack. The arrangement of the present invention provides the ability to uniformly adjust the pre-load of the clutch pack with access external of the differential case.

[0005] FIG. 1 is a sectional view of a differential axle assembly having a limited slip device according to the prior art.

[0006] FIG. 2 is a partial sectional view of a differential axle assembly according to the present invention.

[0007] FIG. 3 is side view of the adjustment collar of FIG. 1 according to the present invention.

[0008] FIG. 4 is side view of the differential case of FIG. 1 according to the present invention.

[0009] The present invention provides the ability to adjust the preload of the limited slip device. FIG. 2 depicts a differential assembly 101 having a limited slip device 103 according to the present invention. Differential pinions 105 and side gears 107 are disposed within a differential case 106. A multiple-disc clutch pack 104 is disposed between one or each of the side gears 107 and the differential case 106 (one shown). The differential case 106 may have axial grooves or splines to prevent rotation and allow axial displacement of friction discs of the clutch pack 104. An adjustment collar 109 is disposed between the limited slip device 103 and the differential case 106. The adjustment collar 109 threadingly engages an annular recess 111 formed in said differential case. Simply rotating the adjustment collar 109 adjusts the preload of the clutch pack 104 of the limited slip device 103.

[0010] The differential gear assembly is mounted within a housing to rotate about an axis of rotation A-A. The side gears 107 are rotatably mounted within the differential case 105 also rotatably about axis A-A. Referring to FIG. 3, the adjustment collar 109 is formed of an annular member and circumscribes axis A-A. Rotation of the adjustment collar causes the adjustment collar 109 to translate along axis A-A. The axial position of the adjustment collar 109 will determined the preload of the clutch pack 104 and limited slip. Therefore, by simply turning the adjustment collar 109, the preload may be adjusted.

[0011] In order to facilitate the rotation of the adjustment collar, a plurality of spanner slots 113 are formed on an outside face of the adjustment collar. To facilitate access to the spanner slots 113, a plurality of elongated arcuate slots 115 are formed through the differential case 106 adjacent the adjustment collar 109. The number of spanner slots 113 and elongated arcuate slots 115 are not critical to the operation of the present invention so long as a tool may be inserted through the elongated arcuate slots 115 to engage a plurality of the spanner slots and permit rotation of the adjustment collar 109.

[0012] Preferably a hand or other tool having a plurality of prongs are inserted through the elongated arcuate slots 115 and engage spanner slots 113. By simply rotating the tool, the adjustment collar is rotated and the preload adjusted. To obtain the desired preload, the tool may be used incrementally whereby the tool engages a first set of spanner slots is retracted and backed off and engages a second set of spanner slots for further rotation until the desired position of the adjustment collar is achieved and the desired preload is obtained.

[0013] The differential case 106 is made of material commonly used to form differential cases such as steel. The adjustment collar is also preferably made of the same material as the differential case. However, other materials of sufficient strength may be employed.

[0014] While the foregoing invention has been shown and described with reference to a preferred embodiment, it will be understood by those possessing skill in the art that various changes and modifications may be made without departing from the spirit and scope of the invention