Patent Publication Number: US-2006000266-A1

Title: Tire condition assessment instrument

Description:
BACKGROUND  
      The present invention generally relates to measuring instruments, and particularly to a measuring instrument suited to measuring at least two parameters indicative of the condition of a vehicle tire.  
      Inflated rubber (synthetic as well as natural) tires are commonly used as the interface between vehicles and road surfaces. Inflated rubber tires absorb some of the bumps encountered on the road, while additionally improving the traction between the vehicle and the road. Tires are often provided with a tread that functions to redirect water and other road debris to improve the traction between the tire and the road. To improve tire performance, tires should be properly inflated and should include sufficient tread to provide the desired traction.  
      Tire inflation and tread condition are especially important for motorcycles where only two tires contact the road. The recommended tire pressure for a motorcycle may vary greatly as a function of the load on the tires (e.g., one rider or two riders) or the riding conditions (e.g., dry pavement vs. wet pavement). As such, it is important to frequently check the tire pressure.  
      Furthermore, excessive tread wear may reduce the traction achieved when riding a motorcycle, especially during adverse weather conditions (e.g., rain, snow, sleet, and the like). Therefore, it is important that the rider also monitor the tread condition on tires.  
     SUMMARY  
      The present invention generally provides a gauge that is capable of measuring two parameters that are indicative of tire condition. Generally, these parameters include the tire pressure and the tread depth. By combining a pressure gauge and a tread depth gauge into a single device, the space occupied by the measuring devices is reduced when compared to two separate gauges. In addition, the combination makes it more likely that a rider will measure both parameters simultaneously rather than just one of the two. This will give the rider a more complete picture of the condition of the tires. The tread depth gauge also indicates the relative condition of the tire using a color-coded tread depth scale. The color-coded scale makes interpretation of the results easy for the rider. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The detailed description particularly refers to the accompanying figures in which:  
       FIG. 1  is a perspective view of a motorcycle;  
       FIG. 2  is a perspective view of an instrument engageable with a tire and operable to measure two tire parameters;  
       FIG. 3  is a partial broken away front view of the instrument of  FIG. 2  illustrating one sensor suited to measuring a tread depth;  
       FIG. 4  is a partial broken away rear view of the instrument of  FIG. 2  illustrating one sensor suited to measuring a pressure;  
       FIG. 5  is a front view of a portion of the instrument of  FIG. 2 ; and  
       FIG. 6  is a perspective view of another instrument engageable with a tire and operable to measure two tire parameters.  
      Before any embodiments of the invention are explained, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof is meant to encompass the items listed thereafter and equivalence thereof as well as additional items. The terms “connected,” “coupled,” and “mounted” and variations thereof are used broadly and encompass direct and indirect connections, couplings, and mountings. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
       FIG. 1  illustrates a motorcycle  10  having a frame  15 , and an engine and transmission assembly  20  mounted to the frame  15 . A steering assembly  25  is pivotally mounted to the frame  15  and a front wheel  30  is rotatably mounted to the steering assembly  25  to support the front of the motorcycle  10 . A rear wheel  35  is rotatably interconnected with the frame  15  and supports the rear of the motorcycle  10 . The rear wheel  35  is driven by operation of the engine and transmission assembly  20 . Each of the front and rear wheels  30 ,  35  includes a tire  40  that is filled with high-pressure air. In general, the recommended air pressure within the tires  40  is above 20 pounds per square inch (psi) with higher pressure being common and lower pressure being possible. Each tire  40  includes a fill valve  45  that is engageable with a standard fill valve fitting  50  (similar to the one shown in  FIG. 2 ) to fill the tire  40  with compressed air. The fill valve  45  can also be used to release air from the tire  40  if desired.  
       FIG. 2  illustrates an instrument  55  that measures two parameters that are indicative of tire condition. The instrument  55  includes a housing  60  that substantially contains a tire pressure gauge  65  or sensor and a depth gauge  70  or sensor. The tire pressure gauge  65  measures the internal tire pressure and the depth gauge  70  measures the depth of the tread on the tire. The instrument  55  also includes a faceplate  75  that includes a first indicator in the form of a first needle  80  and a pressure scale  85  associated with the first needle  80 . The first needle  80  moves in response to the measured pressure. The faceplate  75  further includes a second indicator in the form of a second needle  90  and a depth scale  95  associated with the second needle  90 . The second needle  90  moves in response to the measured tread depth. Other constructions may use other indicators such as, but not limited to, analog or digital readouts.  
      As shown in  FIGS. 2 and 4 , the tire pressure gauge  65  includes a flexible hose  105  having a fill valve fitting  50  at one end. The fill valve fitting  50  engages the fill valve  45  of the tire  40  and opens the valve  45 . While many angles are possible for the valve fitting  50 , preferred constructions use a valve fitting  50  that is oriented at 90 degrees or 45 degrees relative to the flexible hose  105 . Thus, high-pressure air from within the tire  40  flows into, and fills the flexible hose  105 . The second end of the hose  105  connects to the instrument housing  60  and feeds high-pressure air from the hose  105  to a pressure-responsive member  110 . The instrument housing  60  may also include a pressure-release mechanism  115  that can be actuated by the user to release high-pressure air from the tire.  
      The pressure-responsive member  110  includes a hollow C-shaped tube  120  (often referred to as a Bourdon tube) having a first end in fluid communication with the flexible hose  105  and a second end that is sealed and is coupled to a linkage  125 . The linkage  125  includes an arm member  130  that is pivotable about both of its ends and a gear member  135 . A first end of the arm member  130  connects to the sealed end of the tube  120  and a second end of the arm member  130  connects to an extension that projects from the gear member  135 . The gear member  135  engages a second gear  140  that is fixedly attached to the first needle  80  such that rotation of the second gear  140  produces a corresponding rotation of the first needle  80 . A biasing member in the form of a torsional spring  145  biases the needle  80  toward its low-pressure position (illustrated in  FIG. 2 ).  
      While a dial-type pressure gauge and mechanism has been described, one of ordinary skill will realize that other types of pressure gauges (e.g., load cells, capacitive sensors, optical sensors, and the like) could be employed. In addition, other mechanisms or linkages could be employed to measure pressure. As such, the invention should not be limited to only the dial-type gauge and mechanism described.  
      The depth gauge  70 , illustrated in  FIG. 3 , includes a probe  150  that extends from the housing  60  and is fixedly attached to a rack  155 . The rack  155 , disposed substantially within the housing  60 , engages a first gear  160  that is fixedly supported for rotation. The first gear  160  engages a second gear  165  that rotates in the opposite direction as the first gear  160  in response to movement of the rack  155 . A shaft  170  supports the second gear  165  for rotation and also supports the second needle  90 . Thus, movement of the probe  150  produces a corresponding movement of the second needle  90 .  
      Referring to  FIGS. 2 and 4 , the depth gauge  70  also includes a pin  172  that extends above the housing  60 . The pin  172  is connected with the rack such that movement of the pin  172  into the housing  60  produces a corresponding movement of the probe  150  out of the housing  60 . Probes  150  are commonly biased to their maximum extended position. This position often corresponds with the zero depth measurement. In the illustrated construction, the probe  150  is not biased to any position. Rather, friction within the device assures that the probe  150  does not move unless a sufficient force is applied. Thus, the probe  150  can be positioned within the housing  60  when not in use. Positioning the probe  150  within the housing  60  provides additional protection to the probe  150 .  
      Many different parameters can be measured to indicate the condition of the tire  40 . These parameters include, but are not limited to, internal pressure, tread depth, tire thickness, tire resilience, side wall wear, and the like. As such, while the foregoing discussion describes the two gauges  65 ,  70  as a pressure gauge and a tread depth gauge respectively, other gauges that measure other parameters could be employed.  
      Turning to  FIG. 5 , the front of the instrument is shown to better illustrate the faceplate  75 . As discussed, the faceplate  75  includes the pressure scale  85  and the depth scale  95 . The pressure scale  85  interacts with the first needle  80  to indicate the internal pressure of the tire  40 . The scale  85  illustrated in  FIG. 5  shows a gauge pressure measured in pounds per square inch (psig). While the illustrated scale  85  indicates a pressure range between 0 and 60 psig, any suitable range (e.g., 0 to 120 psig) could be employed. Of course, other scales could be used in place of, or in addition to, the one illustrated. For example, a scale that indicates absolute pressure (psia) or indicates the pressure in different units (e.g., metric units such as Pascals, kPa) may also be applied to the faceplate  75 . In addition, two different units could be applied to the same scale if desired.  
      The depth scale  95  interacts with the second needle  90  to indicate the depth of the tire tread being measured. The depth scale  95 , as illustrated in  FIG. 5 , includes increments that are labeled as fractions of an inch. Again, other scales (e.g., metric units such as millimeters, mm) could be used in place of, or in addition to, the one illustrated in  FIG. 5 .  
      Many different tires  40  can be used on vehicles and motorcycles  10 . For example, long life tires can be used on motorcycles  10  that are used for touring. Low-profile tires may be used on motorcycles  10  that are used less frequently. These two types of tires include very different treads. The long life tire, when new, includes a relatively thick or deep tread when compared to a new low-profile tire. As such, a tread depth measurement that indicates one-half of the tread on the long life tire has been worn, may be the same measurement result achieved when measuring the tread of a new low-profile tire. Thus, the actual quantity of tread wear is not indicative of tire life. Rather, the actual tread depth is indicative. No matter the tire employed, a tread depth of about 2/32 of an inch ( 1/16 ) or less indicates a worn tire. Of course some tire manufacturers may indicate that a tire is not worn until the tread depth is less than 2/32 of an inch, or that a tire is worn even when more than 2/32 of an inch of tread remains.  
      Because a tire with a tread depth of 2/32 of an inch or less is generally considered worn out, the second scale  95  includes a color coding scheme that further indicates the status of the tire&#39;s tread. The depths from 2/32 ( 1/16 ) of an inch to zero are located within a first zone  180 . The first zone  180  is colored red to indicate to the rider that the tire tread is worn and that the tire  40  should be replaced. A second zone  185  extends from 2/32 of an inch to a predetermined value, such as 5/32 of an inch as illustrated in  FIG. 5 . The second zone  185  is colored yellow to indicate to the rider that the tire  40  is not completely worn but that it is approaching the end of its useful life. The remainder of the scale  95  makes up a third zone  190 . The third zone  190  is colored green to indicate that the tread depth is adequate. Of course, more or less zones as well as a different color scheme or pattern scheme could be employed if desired.  
       FIG. 6  illustrates another construction of the instrument  200  that also includes a first gauge  65  in the form of a pressure gauge and a second gauge  70  in the form of a tread depth gauge. The pressure gauge and the tread depth gauge are similar to those already described with regards to  FIGS. 2-5 . However, to further reduce the size of the instrument  200 , the construction of  FIG. 6  replaces the flexible hose  105  with a short rigid tube  205  that supports the fill valve fitting  50 . The elimination of the long flexible hose  105  produces a more compact instrument  200  that is easily stored.  
      To use the instrument  55  or  200 , the user connects the fill valve fitting  50  to the fill valve  45  of the tire  40  being evaluated. A small quantity of the air within the tire  40  flows into the flexible tube  105  (rigid tube  205  in the construction of  FIG. 6 ) and fills the C-shaped tube  120 . The high-pressure air tends to straighten the C-shaped tube  120 , which causes the first arm member  130  to move, which in turn moves the gear  135 . The movement of the gear  135  causes the second gear  140  to rotate a corresponding amount to move the first needle  80 . The first needle  80  points to a pressure value, which can be compared to the manufacturer&#39;s recommendations to determine if the tire pressure is suited to the particular riding conditions. If the tire pressure is too high or too low, air can be released or added and the measurement can be repeated until the desired pressure is achieved.  
      The user then extends the probe  150  by pressing down on the pin  172 . The probe  150  is then positioned within a tire tread and the housing  60  is moved into contact with the tire  40 . The rack  155  moves in response to the probe&#39;s contact with the bottom of the tire tread until the housing  60  contacts the outermost surface of the tire  40 . Thus, the probe  150  extends beyond the housing  60  an amount that is substantially equal to the depth of the tire tread. The movement of the rack  155  rotates the associated gears  160 ,  165  to rotate the second needle  90 . The user can simply look at which color zone  180 ,  185 ,  190  the needle  90  is in to evaluate the tire&#39;s tread depth or can look at the actual measurement. Using the instrument  55 ,  205  as just described provides the user with accurate and useful data regarding the condition of the vehicle&#39;s tires  40 .  
      Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of the invention as described and defined in the following claims.