Information
-
Patent Grant
-
6227622
-
Patent Number
6,227,622
-
Date Filed
Friday, June 20, 199727 years ago
-
Date Issued
Tuesday, May 8, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Christensen O'Connor Johnson Kindness PLLC
-
CPC
-
US Classifications
Field of Search
US
- 301 53
- 301 57
- 301 647
- 152 323
- 152 393
- 152 246
- 280 1122
- 280 1123
-
International Classifications
-
Abstract
A skate wheel and method of making the same are provided. The skate wheel includes multiple materials of differing durometers disposed on an inner hub. First, a solid or microcellular urethane is seated on an outer rim of the hub in a ring configuration around the rim. A urethane tire material surrounds the ring. The outer tire material is constructed preferably of a urethane that is more durable and harder than the ring. The ring is made of a highly resilient urethane for high speed. A wheel also is provided with energy absorption to counter rough road surfaces with less loss of energy by the skater, while increasing the traction of the skate wheel on the surface. A method is also provided of making a wheel by pouring differing resins into a mold and either spinning or separating the resins while allowing their interfaces to cure together for bonding therebetween.
Description
FIELD OF THE INVENTION
The present invention relates to wheels for skates such as in-line skates, quad roller skates, and skateboards, and more particularly to wheels with improved speed, shock absorption, vibration absorption, traction, and grip.
BACKGROUND OF THE INVENTION
Skate wheels ideally combine the attributes of resilience, wear resistance, and grip for a smooth ride on various paved surfaces without substantial energy loss and wheel wear. However, conventional in-line skate wheels, such as recreational, racing, and hockey wheels either have good vibration absorption but low wear resistance (soft wheel) or good wear resistance but low vibration absorption (hard wheel).
A skater's speed is also affected by the interaction between the wheel hardness and the roughness of the skating surface. A hard wheel will skate fast on a very smooth surface. However, as the surface becomes rougher, a soft wheel will more smoothly ride over small surface bumps and results in less skater energy loss. A hard wheel requires the skate to move vertically over bumps causing vibrations, extra movement of the wheel, and thus, extra energy expended.
Others have attempted to provide a wheel with improved dampening, resilience, and/or grip. For example, U.S. Pat. No. 4,699,432 (Klamer) discloses a dual material wheel. The surface of the wheel exposes the two materials including the softer material. However, such a wheel may be slow, having increased rolling friction. Furthermore, the soft material would not wear well and will create vibration due to the hardness on the skating surface.
SUMMARY OF THE INVENTION
The present invention includes a wheel that may be used for a skate such as an in-line skate, tandem skate, or skateboard. The wheel includes a hub, a tire circumscribing the hub, and at least one layer or ring between the hub and the tire. The tire is constructed of a first material. The ring is disposed at least partially between the hub and the tire. The ring is constructed of an elastomeric material softer than the first material of the tire construction.
Preferably, the hub includes a rim projecting radially outwardly therefrom. The rim has openings extending therethrough parallel to the rotational axis of the hub. The ring is disposed on the outer periphery of the rim with the tire extending beneath the rim through the openings. Preferably, the ring is in an at least slightly stretched state on the outer periphery of the rim.
The first material, from which the tire is constructed, preferably includes urethane. The elastomer ring or layer material includes a softer urethane than the first material. The ring material in one preferred embodiment includes a solid elastomer. In another preferred embodiment the ring material includes microcellular elastomer (e.g., polyurethane foam). Preferably, the first material includes a urethane with a Shore A hardness between 70A and 100A. The microcellular urethane ring has a density between 10 to 60 pounds per cubic foot. In the solid elastomer ring or layer embodiment, the hardness of the ring is between 20A to 75A on the Shore A scale. The ring's surface is rough so as to bond well to the urethane tire material.
The invention also encompasses a method of making a skate wheel including providing a hub, placing a ring of elastomeric foam around the outer periphery of the hub, placing the hub and the ring within a mold, and inserting tire material into the mold around the hub and ring. In one preferred embodiment of the invention, the ring comprises a microcellular urethane, while the tire material includes a solid elastomer. Preferably, the tire material is poured or cast into the mold.
In the preferred method of carrying out the invention, the hub includes a rim or other extensions projecting radially outwardly from the center portion of the hub and includes transverse openings through the rim. The ring is placed on the outer periphery of the rim or other projections and the tire material flows through the openings to substantially surround the ring. The ring preferably has a rough surface for positive mechanical bonding to the tire material. Alternatively, the tire material may be injected into the mold.
The present invention also encompasses an alternate method of making a dual durometer skate wheel. The skate wheel includes a rotational axis and the method includes placing first and second uncured resin materials in a wheel mold. The second material has a higher density than the first material. The mold is then spun about the rotational axis of the wheel to allow the second, higher density material to be concentrated generally at the outer periphery of the wheel mold. The first and second materials are at least partially mixed (B-stage process) at their interfaces for bonding therebetween. The first and second materials are then cured.
Preferably, at least one of the resin materials includes polyurethane. In one aspect of the preferred embodiment, the first and second materials are preferably poured into the mold.
An alternate method of the present invention includes making a dual durometer wheel by providing a wheel mold, placing a separator within the mold, inserting a first resin material on one side of the separator, inserting a second resin material on the other side of the separator, allowing at least one of the first and second materials to at least partially cure, removing the separator, and curing at least one of the first and second materials (“B-staging”). Preferably, a hub is provided inside both the first and second materials before inserting the materials into the mold. The first material is disposed adjacent the hub at an inner periphery and adjacent the separator at an outer periphery. The second material is adjacent the separator at an inner periphery.
The invention also includes a method of making an in-line skate wheel in a mold by spinning the mold on the axis of the wheel, placing a predetermined amount of first resin material into the mold, and placing a second resin material into the mold within the first material before the first material completely cures. The first material fills less than the complete volume of the mold to allow space for the second material within the first material. Preferably, the first material is allowed to gel before the second material is placed therewithin. Once allowed to gel, the rotation of the mold is stopped before adding the second material. Also, the preferred embodiment of the invention includes a hub inserted into the mold before the second material is placed therein. The hub is placed within the first material such that the second material is placed substantially between the hub and the first material.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings; wherein:
FIG. 1A
is an isometric view of a wheel constructed according to the present invention, the wheel cut in half to display the internal construction;
FIG. 1B
is a sectional isometric view of another preferred embodiment of the present invention;
FIG. 1C
is a sectional isometric view of another preferred embodiment of the present invention;
FIG. 2A
is an isometric view of the hub used with the wheel illustrated in
FIG. 1
;
FIG. 2B
is an isometric view of a ring of material held between the hub and outer tire member of the wheel;
FIG. 3
is a sight elevational view of an alternate embodiment of the wheel of the present invention shown with a separator band;
FIG. 4
is a side elevational view of an alternate embodiment of the wheel of the present invention with intermixed tire and ring materials; and
FIG. 5
is a sectional isometric view of another embodiment of the present invention having multiple durometer layers.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The preferred construction of the dual or multiple durometer skate wheel of the present invention is illustrated in
FIG. 1A. A
wheel
20
includes a hub
22
at the central portion thereof Hub
22
includes conventional recesses within which the outer races of a set of bearings are disposed within the central portion or bore of hub
22
. A tire
24
is secured to the outer periphery of hub
22
. Tire
24
is preferably constructed of a polyurethane material, while hub
22
is preferably constructed of a thermoplastic urethane (TPU) material. As will be explained in more detail below, other materials such as nylon may alternatively be used.
A ring
26
is disposed between tire
24
and hub
22
and totally encapsulated thereby, in the preferred embodiment. Ring
26
extends around the outermost portion of hub
22
and is preferably held in place by tire
24
, which is molded around both ring
26
and hub
22
. The term “ring” as used throughout this description should be understood to include a layer extending at least partially beneath tire
24
. The ring or layer could have various cross sections, widths, shapes, and diameters. It may lie flat against the hub or may float within the tire material removed from the hub as shown in FIG.
1
C. Furthermore, ring
26
may be discontinuous such that it does not completely circumscribe or surround hub
22
, as in
FIG. 1B
where multiple individual narrow projections
27
hold ring
26
. Note that multiple rings or layers may also be used each having the same or differing densities or durometers.
Further details of hub
22
are seen in FIG.
2
A. Bearing recesses
28
are provided for placement of conventional skate bearings therein. Hub
22
includes rim
30
extending around the periphery thereof Rim
30
includes transverse openings therethrough through which tire
24
extends for secure mechanical attachment to hub
22
.
Ring
26
is illustrated separately in FIG.
2
B. Ring
26
is preferably snapped over the outer periphery of rim
30
to be held thereon once tire
24
is molded on hub
22
and rim
30
. Preferably, ring
26
is formed separately from hub
22
and then placed thereon after being molded, cut, or otherwise formed. Ring
26
may consist of a solid elastomer material or a microcellular urethane (polyurethane foam) material. As mentioned above, the ring can vary in density, internal and external diameter, width, urethane formulation, spring rate, skin density (i.e., porosity) and air content. The microcellular or solid urethane is preferably a methylene diisocyanate (MDI), toluene diisocyanate (TDI), or a polyether- or polyester-based polyol or rubber or other soft material. However, other materials softer than tire
24
can be alternatively employed. An interface barrier can be used to enhance bonding between ring
26
and tire
24
.
Once ring
26
is stretched over rim
30
of hub
22
, hub
22
and ring
26
are placed within a mold used to form tire
24
therearound. Tire
24
is formed with a liquid resin injected or poured/cast into the mold and allowed to at least partially cure before being removed from the mold. The resin used to form tire
24
flows through the openings in rim
30
and also into any pores in the skin of hub
22
and in ring
26
for a mechanical bond therebetween. Additionally, chemical bonding can occur between ring
26
and tire
24
to secure their attachment to each other.
The above-described basic construction of wheel
20
can be used to construct wheels with greatly varying properties and uses by changing the sizes or materials used to construct the individual wheel components or by adding multiple rings or layers as shown in FIG.
5
. Ring
26
is preferably constructed with a softer material than tire
24
. Thus, ring
26
allows tire
24
to flatten or increase its footprint (area of the wheel that contacts the skating surface), thereby increasing the wheel's grip on the skating surface. At the same time, tire
24
is constructed of a harder material such that the rolling friction is not substantially increased with the increase in footprint. This allows the skater to turn sharply and skate faster, while the wheels maintain their grip on the skating surface.
Ring
26
also has a dampening effect while absorbing vibrations and shock for a more comfortable and efficient skate. By virtue of the softer nature of ring
26
relative to tire
24
, ring
26
absorbs and dampens the vibrations to afford the skater an increased level of comfort on rough skating surfaces. The wheel can provide suspension action while carrying the dual properties of dampening and compressibility. The amount of air in ring
26
helps control the rebound of the wheel so that there is compression dampening from the microcellular urethane spring and rebound dampening from the internal compressed air. Using rings of varying internal and external diameters, as well as densities and materials, results in wheels with differing properties. Using multiple rings also gives the wheel differing properties (e.g. apparent hardness and/or resilience).
The soft inner ring
26
may be magnitudes higher in resilience and rebound than conventional outer layers, such as tire
24
, that come in contact with skating surfaces. If ring
26
were to contact a skating surface, it would have extremely poor abrasion resistance (wear) and rolling resistance; therefore, the skater would not be able to take advantage of its resilient properties. However, encasing ring
26
within tire
24
provides a wheel with the resilience contributed by ring
26
and higher wear, surface grip, and speed properties than the harder polyurethane tire
24
by itself
A harder tire
24
may be employed with ring
26
while obtaining a tire with an “apparent” durometer and/or resilience (the resulting hardness and traction feel) that provides increased comfort and/or speed.
A racing or speed wheel may be created with the dual durometer combination by providing the ring
26
fabricated from a urethane material with a Bashore rebound of over 75% while the outer tire
24
may be made from a more durable urethane in the rebound range of 60-75%. Urethanes in this range generally have a hardness between 75A and 90A on the Shore A scale. The inner ring or layer would preferably be constructed from a highly resilient urethane solid made from a material in the 20-75 Shore A range. This dual durometer construction increases the speed of the wheel by decreasing the energy losses associated with typical high durometer wheels that ride up and over every small bump on rough pavement. The multiple durometer wheel, in contrast, allows the hard outer tire
24
to compress ring
26
when a small bump is encountered such that it does not require that the skater moves up and over the bump, but rather simply moves tire
24
over the bump relative to hub
22
and the rest of the skate and skater. In other words, the wheel conforms to ride fast over the surface. Thus, the skate wheel continues in more of a straight line forward course without as much vertical movement robbing energy from the skater.
The increased resilience of the dual durometer wheel also increases the speed of the wheel on smooth surfaces. A harder material can be used for tire
24
while maintaining the traction and feel (the apparent durometer) due to the use of ring
26
.
A skate wheel with even higher suspension characteristics can also be created using the two-component concept. If ring
26
is made from microcellular urethane, the rebound will be significantly reduced; however, energy absorption will be greatly increased. This higher energy absorption allows the wheel to travel over rougher surfaces with less overall energy loss by the skater. The resonating action of conventional hard or soft wheels on rough surfaces, while having less energy loss in the tire itself, will have greater energy loss overall due to the resonation and the vibration of the frame/wheel system. Thus the conventional wheels will lose more energy than a less lively (i.e., more highly damped) wheel. The rougher the road surface, the damper the wheel must become to minimize energy loss during rolling. For example, a smooth sidewalk may not require significant additional damping, while a heavily coated (“chipcoated”) surface may require ring
26
to employ a low density microcellular foam material.
Wheels with varied properties may be constructed depending on anticipated road surfaces. For example, for a rough highway, the outer tire material may be constructed of a polyurethane with a hardness somewhere between 75A and 90A, while using a ring of microcellular urethane with a density resulting in 45 pounds per square inch compressive force. Alternatively, if a wheel is to be used with rougher surfaces (i.e., heavy chipcoat), the outer tire may be constructed with 80A to 86A durometer polyurethane and ring
26
of a microcellular urethane with a density of 10 to 60 pounds per cubic foot. In other words, the outer tire can be optimized for wear resistance and speed, while the inner ring can be optimized for energy absorption and resilience depending on the surface.
Various alternate embodiments can be contemplated that utilize the multiple component system described above. For example, hub
22
may not include rim
30
in the same outwardly projecting configuration illustrated in FIG.
2
A. Alternatively, ring
26
may fit into a recess in hub
22
or simply flat on the face of hub
22
along an inner portion of hub
22
. Alternatively, ring
26
may extend the entire width of hub
22
and be bonded thereto with tire
24
bonded to the outer periphery of ring
26
. In alternate embodiments, rim
30
may be discontinuous with portions over which ring
26
extends not contacting rim
30
. Furthermore, ring
26
may simply sit above hub
22
without direct contact therewith, with ring
26
held in place while tire
24
is molded thereabout.
FIG. 3
illustrates an alternate construction of a wheel
120
using multiple durometer materials. Hub
122
is surrounded by ring
126
. Ring
126
is surrounded about its outer periphery by tire
124
. In this embodiment of the invention, ring
126
extends through the entire width of wheel
120
. However, alternate embodiments may include ring
126
extending only through a central portion of the width of wheel
120
. A band
132
is illustrated in FIG.
3
. Band
132
does not remain, preferably, in the finished wheel, but is used in the process of constructing the wheel. The wheel is constructed by pouring resins within a mold to form ring
126
and tire
124
. Band
132
separates the resins while they are in a liquid state in order to maintain the higher durometer tire material about the outer periphery of wheel
120
, while ring
126
, with a softer lower durometer material, remains between tire
124
and hub
122
. Once either tire
124
or ring
126
is cured to at least a gel state, band
132
can be removed while additional curing takes place and bonding between tire
124
and ring
126
occurs. In one embodiment of the method of constructing the wheel according to
FIG. 3
, band
132
may be secured in place and material for ring
126
poured about hub
122
. After ring
126
reaches a gel or semi-cured state, band
132
could be removed and tire
124
could be poured and cured. Thereafter, ring
126
could finish curing and bond to tire
124
in the process. Alternatively, tire
124
may be poured first or both may be poured substantially simultaneously with band
132
in between. Band
132
is, preferably, a Teflon material with low surface friction such that it can smoothly be removed from between the resin materials. Silicone rings or bands may be used in place of Teflon bands since they would also have a low surface energy. Such a separator may be removed after substantially simultaneously pouring the ring and tire and following a waiting period of between 5 seconds and 5 minutes. Alternatively, separate molds may be used such that ring
126
is poured around hub
122
in a first mold, removed from the mold and placed in a second mold, after which tire
124
is poured thereabout. Ring
126
, along with hub
122
, may be removed from the first mold before complete curing of ring
126
so as to enhance the bond between ring
126
and tire
124
.
FIG. 4
illustrates an alternate preferred embodiment of the wheel of the present invention constructed with another preferred method of the present invention. In this embodiment, spin casting is used to form the tire
224
of wheel
220
. In this method, a predetermined amount of tire resin is placed within a mold. The mold is spun about the axis of hub
222
such that the resin forms a tire on the outside of the mold and that tire at least partially cures to substantially hold its shape. The spinning preferably takes place for from 5 seconds to 5 minutes in order to partially cure the resin. The spinning may then be stopped and the inner layer or ring
226
may be poured within the tire
224
. Alternatively, a mixture of resins for ring
226
and tire
224
may be placed within a mold that is at the time spinning or is spun following the placement of the resins into the mold. The resin for ring
226
is of a lower density and thus the resin for tire
224
would move toward the outer periphery of wheel
220
while the resin for ring
226
remains between hub
222
and tire
224
. However, since the resins were mixed, the bond between the two would be strong.
Alternatively, the resins are simply poured into the spinning mold at the same time without being previously mixed; the spinning of the mold would create a separation between them due to their diverse densities with adequate mixture at their interfaces while they cure. In another method of the invention, the tire
224
resin first is poured into the mold and spun for 5 seconds to 5 minutes for partial cure. The second material (less dense) for ring
226
is then poured into the mold or container and spun for 5 to 30 minutes under elevated temperatures. The temperatures may range from 80° to 260° Fahrenheit and the speed may vary from 500 to 5000 cycles per minute in the preferred embodiments of the inventions. The wheel is then demolded and post-cured for 8 to 12 hours at elevated temperatures. A temperature of 2200 Fahrenheit is preferred for post-curing.
While the preferred embodiments of the invention have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.
Claims
- 1. A skate wheel comprising:(a) a hub; (b) a tire circumscribing said hub, said tire being constructed of a first material; and (c) a ring disposed at least partially between said hub and said tire, wherein said tire encapsulates said ring, said ring being constructed of a solid elastomer material softer than said first material.
- 2. The skate wheel of claim 1, further including a second ring disposed between said hub and said tire, said second ring having a different durometer than said tire.
- 3. The skate wheel of claim 1, wherein said hub includes a rim projecting radially outwardly therefrom, said rim having openings extending transversely therethrough, said ring being disposed around the outer periphery of said rim, said tire extending beneath id rim through said openings.
- 4. The skate wheel of claim 3, wherein said ring is in an at least slightly stretched state around the outer periphery of said rim.
- 5. The skate wheel of claim 1, wherein said first material comprises urethane and wherein said elastomer ring material comprises softer urethane.
- 6. The skate wheel of claim 5, wherein said ring material comprises a solid elastomer.
- 7. The skate wheel of claim 5, wherein said ring material comprises microcellular elastomer.
- 8. The skate wheel of claim 7, wherein the first material comprises a urethane having a Shore A hardness between 70A and 100A and wherein the ring has a density of between 10 to 60 pounds per cubic foot.
- 9. The skate wheel of claim 5, wherein said ring surface is rough.
US Referenced Citations (36)
Foreign Referenced Citations (3)
Number |
Date |
Country |
0 714 682 A2 |
Nov 1995 |
EP |
WO 9634666 |
May 1996 |
WO |
WO 9717116 |
Oct 1996 |
WO |