Bearing spacer for in-line skate

A bearing spacer device for axially separating ball bearings in a skate wheel hub includes a generally cylindrical center portion that abuts and axially spaces the individual ball bearings within the skate wheel hub. A central bore extends coaxially through the center portion to receive an axle pin for mounting the skate wheel to a skate. A discontinuity formed in the outer surface of the center portion to reduce weight and improve airflow. The discontinuity may include a plurality of circumferentially spaced longitudinal grooves that extend along the length of the center portion. The discontinuity may alternatively include at least one radial hole that extends completely through the center portion. Reduced diameter cylindrical end portions may integrally extend axially outward from either end of the center portion for mounting the ball bearings.

TECHNICAL FIELD
 This invention relates generally to improved spacers for the bearing
 assemblies for mounting the wheels of in-line roller skates.
 BACKGROUND OF THE INVENTION
 In-line roller skates have seen great popularity. This popularity is due in
 part to constant improvements to decrease the effort to propel oneself and
 make the sport more enjoyable.
 Known bearing assemblies include a pair of axially spaced ball bearings
 concentrically mounted within an annular wheel hub and mounted on a
 generally cylindrical annular bearing spacer or axle sheath. Each ball
 bearing typically includes a plurality of bearing balls mounted between
 inner and outer bearing races. Known bearing spacers conventionally
 comprise an enlarged center portion and reduced end portions. The inner
 races of the two ball bearings are commonly mounted on the respective
 reduced end portions in abutment with the respective opposite radial
 shoulders of the enlarged center portion so that the two ball bearings are
 axially spaced from each other.
 Wheel bearing quality and condition significantly affect the amount of
 effort required to propel oneself on a pair of in-line skates. However,
 even high quality bearings that are in top condition will degrade in
 performance as friction between the bearing balls and the bearing races
 causes heat to build up within those structures. Heat build-up in the
 wheel bearings and bearing races of a typical ball bearing assembly causes
 those parts to expand in size and increases rolling friction. Increased
 rolling friction requires that a skater exert greater effort to maintain a
 given speed.
 What are needed are improvements to wheel bearing assembly design that
 reduce rolling friction by reducing heat build-up.
 SUMMARY OF THE INVENTION
 In accordance with this invention a bearing spacer is provided for an
 in-line skate wheel bearing assembly. The spacer includes a generally
 cylindrical center portion with discontinuities formed in its outer
 surface to improve airflow within the bearing assembly. The center portion
 has a central longitudinal axis that extends between first and second
 center portion ends. A pair of radial shoulders are disposed at the first
 and second center portion ends to abut and axially space the individual
 ball bearings within a hub of the skate wheel. A central bore extends
 coaxially through the center portion to receive an axle pin for mounting
 the skate wheel to a skate.
 According to another aspect of the present invention the discontinuity
 includes a plurality of circumferentially spaced longitudinal grooves.
 According to another aspect of the present invention at least one groove
 extends from the first end to the second end of the center portion.
 According to another aspect of the present invention the discontinuity
 includes at least one radial hole.
 According to another aspect of the present invention at least one radial
 hole extends completely through the center portion.
 According to another aspect of the present invention first and second
 reduced end portions integrally extending axially outward from the
 respective first and second center portion ends. The reduced end portions
 are generally cylindrical in shape. The center bore extends coaxially
 through the first and second reduced end portions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 As shown in FIGS. 1 and 2, an in-line skate 10 has a wheel support bracket
 12 holding wheels 14. The bracket 12 includes two flanges 16 spaced apart
 to fit wheel 14 and its bearing spacer 18. The bearing spacer 18 is
 mounted between the flanges 16 by an axle pin 20 and an axle bolt 22. The
 axle pin 20 is inserted through hole 24 and into the smooth round bore of
 the bearing spacer 18 until its head 30 engages the flange 16 around the
 hole 24. The axle bolt 22 is then inserted into the hole 26 of the
 opposite flange 16 and screwed into the threaded bore of the axle pin 20
 until the head 30 of the axle bolt 22 engages the opposite flange 16
 around the hole 26. Heads 30 each have a hexagonal socket 28 for screwing
 the axle bolt 22 into the axle pin 20 so as to fasten the bearing spacer
 18 to the bracket 12 between the flanges 16. The mounted bearing spacer 18
 is part of a bearing assembly that mounts the wheel 14 for rotation with
 respect to the bracket 12.
 As best shown in FIG. 3, the bearing assembly further comprises two ball
 bearings 35 that are axially spaced from each other by the bearing spacer
 18. Each ball bearing comprises an inner race 37, a complement of bearing
 balls 40 and an outer race 42 disposed within the wheel 14. The bearing
 balls 40 which run in arcuate raceways of the inner and outer races 37 and
 42 are circumferentially spaced by commercially available bearing cages
 54. A bearing cage 54 is inserted into the inboard end of each ball
 bearing 35 and snap fitted into place about the bearing balls 40 of the
 associated ball bearing 35. The outboard end of each ball bearing 35 has a
 sealing cap 55.
 The bearing spacer 18 is shown in detail in FIGS. 4, 5 and 6. The bearing
 spacer 18 separates the individual ball bearings 35 of the bearing
 assembly from each other in the axial direction, prevents over tightening
 of the axle pin 20 and axle bolt 22 and aligns the ball bearings 35
 perpendicular to the axis of the axle pin 20.
 The bearing spacer 18 of the invention comprises an enlarged center portion
 60 and reduced end portions 62 and 64 for receiving and separating the
 respective inner races of the two ball bearings 35 forming part of the
 bearing assembly. However, the enlarged center portion 60 is not solid as
 in conventional designs. The bearing spacer 18 of the invention has a
 plurality of surface discontinuities in the form of circumferentially
 spaced longitudinal grooves 66. The grooves 66 are preferably equally
 circumferentially spaced and preferably extend from end-to-end in the
 outer portion of the enlarged center portion 60. These grooves 66 reduce
 weight of the bearing assemblies which improves the performance of the
 skate wheels 14. The grooves 66 also increase the surface area of the
 enlarged center portion 60 of the bearing spacer 18 which acts as a heat
 sink for the ball bearings 35. The increased surface area dissipates more
 heat generated by the ball bearings 35 during operation and thus the
 grooves 66 also improve the performance of the skate wheels 14 from
 another standpoint.
 While the longitudinal grooves 66 illustrated in the drawing are parallel
 to the longitudinal axis of the bearing spacer 18, other groove
 orientations can be used. For instance, straight grooves skewed with
 respect to the longitudinal axis or helical grooves can be used. Radial
 grooves longitudinally spaced from each other can also be used.
 The bearing spacer 18 can also be mounted to the bracket 12 by threading
 the end portions of the bearing spacer bore and using two axle bolts.
 FIGS. 7, 8 and 9 show another bearing spacer 118 of the invention. This
 bearing spacer 118 is shorter and has a larger bore and the entire bearing
 spacer is grooved from end to end. In this version, longitudinal grooves
 166 parallel to the axis of the bearing spacer are shown. However, other
 groove orientations and shapes as well as mounting arrangements can be
 used as indicated above. The bearing spacer 118 is used in a bearing
 assembly having a larger axle or axle pin 20 in which the ball bearings 35
 are mounted directly on the axle or axle pin 20 with the short bearing
 spacer 118 between the inner spaces. In such cases the bearing spacer 118
 still serves to separate the individual ball bearings 35 of the bearing
 assembly from each other. This is to prevent over tightening of the axle
 pin 20 and axle bolt 22 (or two axle bolts 22) and to align the ball
 bearings 35 perpendicular to the axis of the axle pin 20 or is equivalent.
 FIGS. 10 and 11 show still another bearing spacer 218 of the invention. The
 bearing spacer 218 is similar to the bearing spacer 18 shown in FIGS. 1-6
 in that it comprises an enlarged canter portion 260 and reduced end
 portions 262 and 264. In this version, however, the center portion 260 has
 surface discontinuities formed by a plurality of circumferentially spaced
 radial holes 266 that extend through the center portion 260 in the radial
 direction. These holes 266 reduce the weight of the bearing spacer 218 and
 increase the surface area to improve heat dissipation and wheel
 performance as in the case of the bearing spacers described above. Bearing
 spacer 216 has another advantage in that it has continuous annular
 shoulders 268 at the opposite ends of the center portion 260 for spacing
 the inner races of the two ball bearings while reducing weight and
 increasing surface area for heat dissipation. While a single row of radial
 holes 266 is illustrated, other hole patterns can be used.
 FIGS. 12 and 14 show yet another bearing spacer 318 of the invention. This
 bearing spacer 318 is also short with a larger bore as in the case of the
 bearing spacer 118 shown in FIGS. 7, 8 and 9. However in this bearing
 spacer 318 radial holes 366 are again used to reduce weight and increase
 surface area, as is the case of the bearing spacer 218 shown in FIGS. 10
 and 11. The bearing spacer 318 is used in the same type of bearing
 assembly as the bearing spacer 118.