Patent Publication Number: US-2012032793-A1

Title: Visual wheel end assembly high-temperature warning system

Description:
CROSS-REFERENCE TO RELATED APPLICATION DATA 
     This application claims priority to U.S. Provisional Patent Application No. 61/369,537, entitled “Visual Wheel End Assembly High-Temperature Warning System” filed Jul. 30, 2010, which is hereby entirely incorporated by reference. 
    
    
     FIELD 
     The disclosed system relates generally to visual high-temperature warning systems for vehicles. 
     BACKGROUND 
     In the event of a failure associated with the wheel end, such as a bearing failure or brake failure, elements of the wheel end can heat up and reach high temperatures very quickly. When these high temperatures are reached by the wheel end, tires and/or lubricant may ignite and cause the wheel to lock up or the vehicle to burn. Due to the intense heat caused by a wheel end failure, it is also possible that the wheel can detach from the axle. 
     SUMMARY 
     A high temperature warning system for a wheel end assembly rotatable on an axle on a vehicle, the system comprising an air pressure supply; a normally-closed valve in sealed fluid communication with the air pressure supply; a heat sensitive control capable of opening the normally-closed valve upon a predetermined temperature, the heat sensitive control mounted on or near the steer-axle wheel end assembly in a heat exchange relationship therewith; a warning indicator connected to the air pressure supply for actuation upon opening of the normally-closed valve; and a thermochromic temperature indicator affixed to the wheel end assembly in a heat-exchange relationship therewith, the thermochromic temperature indicator capable of changing color when heated to the predetermined temperature. 
     In a vehicle having an automatic tire inflation system for providing air to a rotating tire on a wheel end assembly comprising a hubcap and rotatably mounted on bearings on a hollow axle connected to an air pressure supply for supplying air to the inside of the axle, a rotary connection in communication between the tire and air inside of the axle, the combination of a high-temperature warning system comprising a normally-closed valve connected between the inside and the outside of the axle in connection with the air in the axle; a heat sensitive control connected to and actuating said valve open upon a predetermined temperature, said control mounted in a heat-exchange relationship with said wheel assembly for detecting the temperature of the wheel assembly; a warning system connected to the air supply for actuation upon opening of the valve; and a thermochromic temperature indicator affixed to the wheel end assembly in a heat-exchange relationship therewith. 
     An automatic tire inflation system for providing air to a rotating tire on a wheel end assembly rotatably mounted on bearings on a hollow axle, the system comprising an air pressure supply for supplying air through the inside of the axle; a rotary union configured to sealingly communicate air from the inside of the axle to the tire; and a thermochromic temperature indicator affixed to the wheel end assembly in a heat-exchange relationship therewith, the thermochromic temperature indicator capable of changing color when heated to a predetermined temperature. 
     A high temperature warning system for a wheel end assembly rotatable on an axle on a vehicle, the system comprising a wheel end assembly comprising a hub cap, a hub, an axle and bearings, the system comprising a temperature indicator affixed at or near the hub cap, hub, axle or bearings, and in a heat exchange relationship with at least one of the hub cap, hub, axle and bearings; wherein the temperature indicator is positioned to be visible to a user; and wherein the temperature indicator comprises a thermochromic material; and wherein the temperature indicator is capable of changing color when heated to the predetermined temperature. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  illustrates one embodiment of a vehicle that may use a visual wheel end assembly high-temperature warning system. 
         FIG. 2  illustrates the trailer axles of  FIG. 1  having a visual high-temperature warning system and an automatic tire inflation system installed. 
         FIG. 3  illustrates a side view of one embodiment of a wheel end assembly comprising a visual wheel end assembly high-temperature warning system. 
         FIG. 4  illustrates a perspective view of another embodiment of a wheel end assembly comprising a visual wheel end assembly high-temperature warning system. 
         FIG. 5  illustrates a cross-sectional view of another embodiment of a wheel end assembly comprising a visual wheel end assembly high-temperature warning system, a high temperature warning system, and an automatic tire inflation system. 
         FIG. 6  illustrates a perspective view of another embodiment of a wheel end assembly comprising a visual wheel end assembly high-temperature warning system and an high temperature warning system. 
         FIG. 7  illustrates a cross-sectional view of another embodiment of a wheel end assembly comprising a visual wheel end assembly high-temperature warning system and a high temperature warning system. 
     
    
    
     DETAILED DESCRIPTION 
     As may be seen in  FIG. 1 , a vehicle  100  may comprise a truck  102  and a trailer  104 . The truck  102  may include one or more drive axles  106  as part of the vehicle&#39;s powertrain. The truck  102  may further include a steer axle (not shown in detail) having pivotable spindles that may provide steering capability for the vehicle  100 . The trailer  104  may include one or more fixed axles (not shown). Each axle may have one or more wheels  108  mounted thereto. A pneumatic tire  110  may be mounted to each wheel  108 . 
     The vehicle  100  may be provided with an automatic tire inflation system (such as is shown in  FIG. 2 ) that uses pressurized air from the vehicle&#39;s air brake system or some other source of pressurized air to maintain the tires at a desired air pressure. The automatic tire inflation system may be used to control air pressure in one or more of the tires  110  mounted to the steer (not shown), drive  106  and trailer axles (not shown). The automatic tire inflation system may include one or more air hoses  112  in fluid communication with each tire  110  for communicating air from the air pressure source to and from one or more of the tires  110 . 
       FIG. 2  illustrates in more detail multiple embodiments of an automatic tire inflation system for trailer tires. A trailer  200  may include two axles  202  and  204 . Some trailers may have dual tires  206  and  208  mounted at each end of the axles, as may be seen with respect to axle  202 . Other trailers may have one wide-base tire  210  mounted at each end of the axles, as may be seen with respect to axle  204 . The automatic tire inflation system may generally include a pressure regulator  214  and one or more rotary air connections or rotary unions  216  and  218  mounted in or near the axle ends. Rotary air connections may be provided in a variety of configurations, such as those disclosed in U.S. Pat. Nos. 6,105,645 and 6,698,482, and in U.S. Pub. App. No. 2009/0283190. The pressure regulator  214  may receive pressurized air from an air pressure source  220  through a conduit  212 . The air pressure source  220  may comprise, for example, a vehicle air brake system air supply, or a step-up or booster pump. The pressure regulator  214  may control or reduce the air pressure from the air pressure source  220  to an air pressure level suitable for inflating the tires  206 ,  208 ,  210 , such as 110 psi. Pressurized air may flow from the pressure regulator  214  through conduit  222  to the axles  202  and  204 . Axles  202  and  204  may, for example, carry an air conduit to communicate pressurized air to rotary air connections  216  and  218 , such as is disclosed in U.S. Pat. Nos. 6,325,124 and 7,273,082. 
     Axles  202  and  204  may be hollow sealed axles. In one embodiment, axle  204  may be hollow and may be sealed to serve as a conduit for pressurized air. The air conduit  222  may be sealingly connected to the axle  204  to allow pressurized air to flow from the pressure regulator  214  to the axle  204 . The pressurized air may flow through the axle  204  to a rotary air connection  216  mounted in or near the spindle end as described in more detail below. An air hose  224  may be connected to the rotary air connection  216  to the valve stem (not shown) of the wheel  209  to which the tire  210  is mounted, thus allowing pressurized air to flow to and from the tire  210 . 
     In some embodiments, the air conduit  222  may be sealingly connected to a tee  226  to allow pressurized air to flow both to axle  204  and to axle  202 . An air conduit  228  may allow pressurized air to flow from the tee  226  to a conduit  230  disposed in axle  202 . Axle  202  may carry an air conduit  230  to communicate pressurized air to rotary air connection  218 . Air hoses  232  may connect the rotary air connection  218  to the valve stems of the wheels  211  to which tires  206  and  208  are mounted, thus allowing pressurized air to flow to and from the tires  206  and  208 . In other embodiments, if the axle  202  is solid, then a channel may be bored in axle  202  to permit positioning of all or part of conduit  230  inside the axle  202 . 
     As noted above, the axles  202  and  204  may be wholly or partially solid or hollow, and may be configured in a variety of ways. For illustration purposes only, axles  202  and  204  are hollow. For example, in some embodiments, an axle may comprise a solid beam having a spindle attached to each end (not shown). The axle spindles may be configured to allow mounting of wheel bearings upon which a hub may be rotatably mounted (not shown). In other embodiments, an axle may comprise a hollow tube having a spindle attached to each end. The spindles may be hollow, resulting in a hollow axle that is open at each end. The open end may be sealed so as to allow the hollow axle to hold pressurized air and to support air conduits or rotary air connections (or components thereof), for example, with a plug or cap disclosed in one of U.S. Pat. Nos. 5,584,949, 5,769,979, 6,131,631, 6,394,556, and 6,938,658. Alternatively, the spindles may be wholly or partially solid, resulting in a hollow axle that is closed at each end. 
     Similarly, automatic tire inflation systems may be used for drive axles (not shown), and air conduits or channels may be provided in the drive axles to allow air flow from a pressure regulator  214  to a rotary air connection, for example as disclosed in U.S. Pat. Nos. 5,377,736 and 7,690,412. In yet other embodiments, again with reference to  FIG. 2 , air conduits (not shown) may run from the pressure regulator  214  along the outside of the vehicle trailer  200 , and connect to the rotary air connections  216  and  218 . Thus, an automatic tire inflation system may be adapted to work with a variety of axles, whether solid or hollow, sealed or unsealed, or fixed, drive or steer. 
       FIG. 3  illustrates a wheel-end assembly  300  similar to the wheel-end assembly mounted to axle  202  in the embodiment of  FIG. 2 , but without an automatic tire inflation system attached thereto, that may include a visual wheel end assembly high-temperature warning system. The visual wheel end assembly high-temperature warning system may provide a visual indication of the temperature of the wheel end assembly  300  so that a driver may determine which wheel end assembly  300  (or assemblies) has reached a predetermined temperature. 
     If the bearings, brakes, or other elements of the wheel end fail, the temperature in the bearings, brake drum, hub, wheel, hubcap or other wheel end components may reach in a temperature high enough to ignite the tires and bearing lubricant. Such heat may also be sufficiently high to cause the wheel end assembly to detach from the axle. The disclosed high-temperature warning system may warn the vehicle operator of high temperatures well before the tires ignite or bearings melt, or some other dangerous high-temperature related condition arises in the wheel-end. A pre-determined temperature may be, for example, a temperature well below the softening or melting point of the bearing materials, or well below the tire melting point. The pre-determined temperature may be set well above the maximum temperatures at which a wheel-end assembly may normally operate so as to avoid false indication of high temperatures. 
     The visual wheel end assembly high-temperature warning system may comprise a visual temperature indicator  304  that is a part of, adjacent to, or affixed to the wheel end assembly  300 , so as to provide a visual indication of subjection to higher temperatures. In one embodiment, the visual temperature indicator  304  may comprise a Thermax® temperature indicator or strip which may be affixed, such as by adhesive, to a portion of the wheel end assembly  300 , for example the hubcap  302 . In another embodiment, the visual temperature indicator  304  may comprise a thermochromic paint  208  applied to the hubcap  302  (as shown in  FIG. 3 ) or other elements of the wheel end assembly  300 . In yet another embodiment, the visual temperature indicator  304  may comprise part of, or all of, the hubcap material. The hubcap  302  or a portion thereof may be made of a thermochromic material, such as plastic having thermochromic pigment. Generally, thermochromic plastics and other materials are available for various reference temperatures as identified by different colors that change when the applied temperature becomes substantially equal to or greater than the reference temperature. In other embodiments, the visual temperature indicator  304  may visually indicate exposure to a higher temperature with a change in appearance in addition to a change in color, such as a change to shape, size, orientation or otherwise. The visual temperature indicator  304  may provide a color change with respect to temperature gradient markings so as to indicate an approximate temperature. In another embodiment, the visual temperature indicator  304  may be a clear color or a white color until a predetermined temperature is reached, at which point the visual temperature indicator  304  may change to another color, such as a blue or red color. Additionally, the visual temperature indicator  304  may be easily replaced and/or be capable of transforming between indicating and non-indicating modes, such as by returning to a default color after cooling off. In one embodiment, the visual temperature indicator  304  may comprise a thermochromic ink, paint, paper, polymer, or other suitable element which is connected to an element of the wheel end assembly  300 . 
     The visual temperature indicator  304  may be any suitable size or shape and may be attached to any suitable area in a heat-exchange relationship with the wheel end assembly  300 . In  FIG. 2 , for example, a visual temperature indicator  306  may be affixed to each wheel-end assembly (not shown). Thus, a user may observe the visual temperature indicators to determine which, if any, of the wheel-end assemblies has reached the predetermined temperature. In one embodiment, such as that of  FIG. 3 , the visual temperature indicator  304  may change from a neutral color to a color that indicates a high temperature so that a driver can easily see if the hubcap  302  has reached the predetermined temperature. Additional visual temperature indicators may be located at different locations  306  and  308  on the wheel end assembly  300  to show whether other components of the wheel end assembly  300  have reached the predetermined temperature. In the embodiment of  FIG. 3 , the wheel end assembly  300  also includes a visual temperature indicator located at  312  on a surface of the wheel  310  between the lug nuts  314  to show the temperature of the surface of the wheel  310 . Of course, only one suitably located visual indicator need be used; however, using more than one may be desirable should one visual indication become detached, or prove defective or damaged. 
     In some embodiments, a visual temperature indicator may include a thermochromic material which is UV-sensitive. As shown in the wheel-end assembly of  FIG. 4 , the visual temperature indicator  402  may be substantially shielded from UV exposure to reduce the risk of inaccurate temperature readings or degrading the temperature indicator. For example, the visual temperature indicator  402  may be located behind a clear sightglass  404  within an end of the hubcap  406 . In other embodiments, the visual temperature indicator  402  may be located on the wheel hub  410 , brake drum  412 , wheel  413 , or other area of the wheel end assembly  400  which is substantially shielded from direct UV exposure. In the embodiment of  FIG. 4 , a visual temperature indicator  408  may be located on a lateral surface  414  of the hubcap  406 . The additional visual temperature indicator  408  may comprise a plurality of thermochromic pigments  416 , each of which may change color at a different temperature and may be labeled with a temperature or temperature range at which the pigment changes color. Thus, a user may observe the approximate temperature of the wheel end assembly  400  by viewing which thermochromic pigments  416  have become visible or changed color. 
     The vehicle  100  of  FIGS. 1 and 2  may include both a visual wheel end assembly high-temperature warning system and an automatic tire inflation system. Visual temperature indicators may be located on one or more wheel-end assemblies as described in connection with  FIGS. 3 and 4  such that they are still visible to a driver while the air hoses  224 ,  232  are connected with the air connections  216 ,  218 . For example,  FIG. 5  illustrates several embodiments of a wheel end assembly which include both a visual wheel end assembly high-temperature warning system and an automatic tire inflation system. As described above, the automatic tire inflation system may include a pressurized air supply  220  (as shown in  FIG. 2 ) used to provide pressurized air to brakes (not shown) and/or an automatic tire inflation system. While the present invention can be used with various types of automatic tire inflation systems, it is useful with the system shown in  FIG. 5  and more fully described and illustrated in U.S. Pat. Nos. 5,769,979 and 6,698,482, both of which are hereby incorporated by reference. Referring to  FIG. 5 , the reference number  500  generally indicates the rotary air connection for supply air from a pressurized air supply  220  on a vehicle to a rotating tire  206 ,  208 ,  210  on a vehicle. A hub cap  502  may be provided at each end of the axle  504  for retaining lubricant in the wheel bearings. The pressurized air supply  220  (as shown in  FIG. 2 ), either directly through the axle  504  or through an interior conduit within the axle  504  (not shown), may supply air to the rotary air connection  500  and then to the rotating tires  206 ,  208 ,  210 . A force fit plug  506  may be positioned in the center of an end of the axle  504  to sealingly engage the interior of the axle  504  by seal  508  if air is injected directly into the inside of axle  504 . The rotary air connection  500  may include a first stationary part  510  having a passageway  512  therethrough. The passageway  512  may be in communication with the pressurized air supply  220  (as shown in  FIG. 2 ). A first resilient rotary seal  514  may be supported in the passageway  512  and may encircle the passageway  512 . The rotary air connection  500  may include a second rotatable part including a tubular member  516  having a first end  518  and a second end  520 . The second end  520  may be coaxially extendable through and longitudinally and rotationally movable in the passageway  512  and may sealable engage the rotary seal  514 . The second end  520  may therefore be in communication with air from the pressurized air supply  220  (as shown in  FIG. 2 ). The first end  518  of tubular member  516  is sealably connected to the air connection  522  on the hub cap  502  through a seal  524 . The air connection  522  may be provided on the hub cap  502  for connected to the tire or tires  206 ,  208 ,  210  through hoses  526 . The first end  518  of the tubular member  516  may include a shoulder which intersects a bearing  528 . In operation, air may be supplied through the stationary part  510  to the tubular member  516  and then to the air connection  522  while the hub cap  502  and tires  206 ,  208 ,  210  are rotating. In some embodiments, the tubular member  516  may remain substantially stationary while the hub cap  502  and tires  206 ,  208 ,  210  rotate. As shown in  FIG. 5 , visual temperature indicators  530  may be located at different positions on the wheel end assembly and may be positioned so that they are visible while the hoses  526  are attached to the air connection  522 . In the embodiment of  FIG. 5 , visual temperature indicators  530  are attached to a top, lateral side, and flange of the hub cap  502 . 
     As shown in  FIGS. 6-7 , the visual wheel end assembly high-temperature warning system may also be used in connection with other high-temperature warning systems, such as the high-temperature warning systems of U.S. Pat. Nos. 6,892,778 and 7,416,005, and PCT Application No. PCT/US11/44879, the disclosures of which are incorporated herein in their entirety by reference. As shown in  FIGS. 6-7 , a high-temperature warning system may be installed on a vehicle, such as the vehicle  100  of  FIG. 1 . An exemplary wheel end assembly  600  may be mounted to the spindle  601  of an axle  602 , and may include a wheel hub  604  that rotates on inner and outer bearings  606  and  608 . The hub  604  may comprise a brake drum  610 , and may be include lugs  612  to support one or more wheels  614  having pneumatic tires (not shown) mounted thereto. In the event of a bearing failure or a brake failure, the temperature in the bearings  606  and  608 , the brake drum  610  and spindle  601  may increase in temperature at which the tires  110  or bearing lubricant (not shown) may ignite, causing a fire, or the bearings may melt, causing detachment of all or part of the wheel end assembly from the axle. 
     The high-temperature warning system may, in one embodiment, include a pressurized air supply  632 , a pressure regulator and flow switch  616 , and a warning system light  618 . The pressurized air supply  614  may include the axle  602  which may be hollow and may be connected to the pressurized air supply  614  through air line  620 . An axle plug  622  may seal each end of the axle  602  whereby the interior of the axle  602  may form part of the pressurized air supply  614 . One or more normally-closed valves  624  may be connected between the inside and the outside of the pressurized air supply  514 , including the hollow axle  602  and spindle  601 . The normally-closed valves  634  may be configured to make an audible noise when air is allowed to pass through the normally-closed valves  634 . The normally-closed valves  634  may be controlled by heat sensitive controls. The heat sensitive controls may be configured to detect temperature and to open the normally-closed valves  634  when a predetermined temperature is reached. Thus, when the temperature near the heat sensitive controls reaches the predetermined temperature the heat sensitive controls may open the normally-closed valves  634  to allow air to pass through the normally-closed valves  634 . 
     The heat sensitive control, in one embodiment, may be a fusible plug  532  (as shown in  FIG. 5 ) comprising an eutectic alloy that seals the normally-closed valve  634 . The fusible plug  532  may open the normally-closed valve  634  upon a predetermined temperature by melting sharply at the predetermined temperature and thus un-sealing an aperture  534  (as shown in  FIG. 5 ) that runs through the normally-closed valve  634 . Thus, the fusible plug  532  may be automatically removed from the aperture  534  when the predetermined temperature is reached. While any type of fusible plug may be satisfactorily used, one sold under the trademark LEEKPRUF sold by the Mueller Refrigeration Company, Inc., is suitable. In some embodiments, when a normally-closed valve  634  is open, pressurized air is allowed to flow through the normally-closed valve  634 . This flow of pressurized air may be detected by a flow switch which actuates the warning system light  618  which is positioned within view of the driver of the vehicle  100  to indicate a problem. 
     A vehicle may include more than one wheel end assembly. Vehicles such as those shown in  FIGS. 1 and 2 , for example, may have a wheel-end assembly mounted to the end of each axle, whether a fixed, drive or steer axle. Thus, if a high-temperature wheel-end warning system such as is described in connection with  FIGS. 6 and 7  is used, it may not be immediately apparent which wheel end assembly has suffered a temperature sufficiently high to activate the high-temperature warning system. For example, if the eutectic alloy in a fusible plug  532  melts, the releasing air may generate a loud screeching sound. The volume and pitch of such sound may hinder ready identification of which normally-closed valves  634  has opened. Visual temperature indicators may be located on one or more wheel-end assemblies as described in connection with  FIGS. 3 and 4  such that they are visible to a driver or maintenance personnel servicing the vehicle. As shown in  FIGS. 5-7 , for example, visual temperature indicators  530  may be mounted in various locations on the wheels, hub and brake drum to allow a driver or maintenance person to identify the particular wheel-end at a dangerously high temperature. 
     Referring again to  FIG. 5 , the wheel end assembly may be equipped with a visual wheel end high-temperature warning system, a high-temperature warning system and an automatic tire inflation system. As illustrated in  FIG. 5 , air from the pressurized air supply  220  (as shown in  FIG. 2 ) may be supplied through the axle  504  for both the automatic tire inflation system and the high-temperature warning system. Thus, air may be supplied through stationary part  510  to the tubular member  516 , to the air connection  522  and then to the hoses  526 . Air may be supplied to the rotating tires  206 ,  208 ,  210  without expelling air through the aperture  534  because the fusible plug  532  may seal the aperture  534 . However, if the fusible plug  532  melts and opens the normally closed value  536 , air may be released through the aperture  534  and the flow switch  536  may sense the additional release of air from the pressurized air supply  220 . The warning system light  534  may alert the driver that air is being released from the pressurized air supply  220 . 
     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition, or matter, means, methods and steps described in the specification. As one will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods or steps.