Abstract:
A tire pressure indicator carried on a tire being monitored for inflation pressure. The indicator includes a housing enclosing an indicating member bearing color coding corresponding to proper inflation. Preferably, additional color coding is provided corresponding to excessive tire pressure and to low or inadequate tire pressure. The indicating member occupies a chamber and air pressure from the tire acting on the indicating member, and is moved in response to tire pressure such that the appropriate color coding is revealed through a window formed in the housing.

Description:
RELATED APPLICATION 
     The present application is a continuation in part application of U.S. patent application Ser. No. 09/170,291, filed on Oct. 13, 1998, now U.S. Pat. No. 5,979,232, issued on Nov. 9, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to pressure gauges of the type carried on a vessel being monitored. More particularly, the invention relates to a mechanical indicator of pneumatic pressure which indicates by color coding whether the pressure being monitored is within specifications. In alternative embodiments, the novel indicator cooperates with or is an integral part of a valve enabling the vessel to be filled with compressed gas. 
     2. Description of the Prior Art 
     Pneumatic tires are designed to operate at pressures within narrow predetermined ranges. Typically, tires lose pressure and must be reinflated to specified values by the operator. This maintenance operation requires a pressure gauge. Many operators rely upon service facilities offering compressed air to supply the gauge. If the service facility does not supply a gauge, the operator of the vehicle is obliged to furnish the gauge. It is easy to neglect to bring a tire pressure gauge at all times, and the operator may therefore lack a gauge when desiring to restore or check tire pressure. Even if a pressure gauge is at hand, it is not always convenient to utilize typical tire pressure gauges. Pressure gauges are normally designed to operate when pressed against the valve of the tire sufficiently to release pressure so that it may be measured and indicated. Under conditions of severe temperatures, dust, rain, and other influences, it may prove difficult or unpleasant to check tire pressure. 
     One answer to this problem is to furnish a pressure gauge that is left in place on the tire, the gauge having an indicator which may be readily viewed to ascertain tire pressure. Such gauges have been proposed in the prior art. 
     In an indicator shown in U.S. Pat. No. 5,569,849, issued to Craig Cummings on Oct. 29, 1996, a colored liquid flows around a solid member obstructing view of the colored liquid when tire pressure deviates from a predetermined setpoint. Visibility of the colored liquid indicates inadequate pressure. By contrast, in the present invention, a solid colored member aligns with a window formed in the indicator. In the novel indicator, air pressure from the tire acts directly on the solid member. No fluid apart from compressed air contained in the tire is employed. 
     U.S. Pat. No. 5,103,670, issued to Min-Yu Wu et al. on Apr. 14, 1992, shows an indicator having a bellows operated piston which, when appearing in a window formed in the indicator, aligns with indicia indicating pressure values. By contrast with this approach, the present invention exposes indicia, preferably in the form of a predetermined color, which enables immediate discernment of whether pressure is within specifications. There are no bellows in the present invention. 
     U.S. Pat. Nos. 5,503,012 and 5,606,123, issued to Masoud Rabizadeh respectively on Apr. 2, 1996, and Feb. 25, 1997, both are based on a ball visible through a window which aligns with indicia. Rabizadeh improves on prior art devices by providing a magnifying glass over the window. However, graduation indicia must still be read in order to determine pressure within the tire. In the present invention, mere discernment of color is required to obtain the same information. There is no magnifying glass required in the present invention. 
     The subject indicator shown in U.S. Pat. No. 5,641,902, issued to Jung Un Hong on Jun. 24, 1997, incorporates an inflatable member which displays indicia indicating inflation pressure. By contrast, in the present invention, a color signal is visible through a window to indicate tire pressure. There is no inflatable member in the present invention. 
     None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. 
     SUMMARY OF THE INVENTION 
     The present invention enables a vehicle operator to determine sufficiency of tire pressure at a glance. There is no necessity of pressing an instrument against the valve. It is not even necessary that the indicator be fully visible and unobscured, since any glimpse of a predetermined color immediately conveys the sought information. Therefore, minor accumulation of dust and dirt, which are normally present under driving conditions, would usually not affect function of the invention. 
     The invention comprises a tubular housing or body which protrudes inwardly radially from a wheel, in the usual location of filling valves for pneumatic tires. It has a window revealing an indicating member which is color coded to indicate tire pressure relative to predetermined pressure values. The indicating member has colors signifying excessive pressure, proper pressure, and low pressure. The user will determine at the state of inflation of the tire at a glance. 
     The novel indicator may be fabricated to mount to conventional filling valves by a threaded attachment. Alternatively, it may be configured to supersede the usual filling valve. In either form, the novel indicator is carried on the tire being monitored for pneumatic pressure after installation, and need not be removed. The novel indicator is optionally configured to enable inflation in the usual manner without removing the indicator from the valve or tire. 
     Accordingly, it is a principal object of the invention to provide a tire pressure indicator that is carried on a tire being monitored. 
     It is another object of the invention that the novel indicator provide visual indication of whether the pressure is within specifications by color coding. 
     It is a further object of the invention to indicate high and low pressure conditions as well as proper inflation pressures. 
     It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes. 
     These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various other objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
     FIG. 1 is a side cross sectional view of one embodiment of the invention. 
     FIG. 2 is a side cross sectional view of a second embodiment of the invention. 
     FIG. 3 is a side elevational view of a third embodiment of the invention. 
     FIG. 4 is a side elevational view, taken in partial cross section, of a fourth embodiment of the invention. 
     FIG. 5 is a side elevational view, taken in partial cross section, of a fifth embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 of the drawings illustrates an embodiment of the invention adapted to be installed on a conventional filling valve stem (not shown) of a pneumatic tire. In this embodiment, tire pressure indicator  10  comprises a generally cylindrical housing  12  having an inner chamber  14  and a window  16  exposing inner chamber  14  to the exterior of housing  12 . Housing  12  is fabricated from a suitable strong, opaque material, such as metal or a synthetic resin. Window  16  is solid rather than open, but is formed from a transparent material. Window  16  closes inner chamber  14  so that external air pressure cannot influence events occurring within inner chamber  14  responsive to tire pressure. In the embodiment of FIG. 1, window  16  forms a transparent circumferential band encircling inner chamber  14 , so that the interior is visible from the side of indicator  10  in any direction. 
     A connecting portion or connector  18  is formed at the lower end of inner chamber  14 . Connector  18  extends housing  12 , and bears threads  20  enabling indicator  10  to be threaded to the threads of the filling valve stem (not shown). A wall  22  is formed at the bottom of chamber  14 . An air passage  24  formed in connector  18  establishes pneumatic communication between chamber  14  and air generating pressure within the tire. 
     A projection  26  for depressing the valve of the filling valve assembly depends from wall  22 . Wall  22  also has openings  28  to conduct air pressure from air passage  24  into chamber  14 . 
     An indicating member  30  is slidably disposed within chamber  14 , and is arranged to pass by window  16 . Indicating member  30  has a first external area designated at  32  colored with a first predetermined hue for indicating proper pressure within the tire, a second external area designated at  34  colored with a second predetermined hue, and a third external area designated at  36  colored with a third predetermined hue. Colored areas  32 ,  34 ,  36  provide color coding visible through window  16  to indicate the state of inflation of the tire relative to predetermined ranges of pressure preferred by the tire or vehicle manufacturer. Preferably, proper inflation is signaled by green, which conventionally is associated with an operative condition. Excessive pressure is signaled by red, and inadequate or low pressure is signaled by yellow. 
     Indicating member  30  is acted on by two opposing forces. Pneumatic pressure from the tire is conducted through passage  24  and openings  28  so that it urges member  30  upwardly, as depicted in FIG. 1. A compression coil spring  38  of predetermined spring rate is disposed within chamber  14  on that side of indicating member  30  opposite the side exposed to tire pressure. Indicating member  30  moves within chamber  14  responsive to differential in force between spring force of spring  38  and pneumatic pressure conducted from the tire to chamber  14 . As indicating member  30  moves responsively to the two forces, an appropriate colored area  32 ,  34 , or  36  aligns with window  16 , and is visible from the outside. The spring rate is selected such that colored area  32  aligns with and is visible through window  16  when tire pressure is within the acceptable range, area  34  aligns with window  16  when tire pressure is excessive, and area  36  aligns with window  16  when tire pressure is too low. 
     In this scheme of operation, pressure of the tire is indicated relative to a predetermined range of pressures, and is not directly measured. In operation of most vehicles having pneumatic tires, it is really not necessary to establish the actual pressure, but merely to know whether the tire pressure is within an acceptable range of pressures. Reading indicator  10  is easier than attempting to discern indicia indicating numerical values of actual pressures, since such indicia is likely to become obscured by dirt and dust as the vehicle is used. It is also not necessary to correlate a measured numerical value to values of the acceptable range of pressures. 
     FIG. 2 illustrates a second embodiment of the invention which provides the features of the embodiment of FIG. 1, and adds a feature enabling the tire to be charged with compressed gas without removing the novel tire pressure indicator from the tire. In the embodiment of FIG. 2, tire pressure indicator  110  includes a housing  112  and a connector  118  both functioning in a manner similar to their counterparts of the embodiment of FIG.  1 . An indicating member  130  bearing three colored areas  132 ,  134 ,  136  is slidably disposed within chamber  114  such that the colored areas  132 ,  134 ,  136  become visible through window  116  formed in housing  112 . A spring  138  opposes force applied by pneumatic pressure conducted from a tire (not shown) through connector  118  into chamber  114 . These components are functional counterparts of similar components shown and described with reference to FIG. 1, and therefore need not be further described herein. 
     Indicator  110  has a bypass conduit  140  disposed in pneumatic communication with air passage  124  of connector  118 . Bypass conduit  140  has a passageway  142 , which contains a check valve  144 . Check valve  144  closes passageway  142  at a valve seat  146 . A spring  148  urges check valve  144  against seat  146 . Force of spring  148  is readily overcome when an air chuck (not shown) or other apparatus for charging the tire with compressed gas is placed over the upper end  150  of bypass conduit  140 . Preferably, upper end  150  is configured similarly to corresponding parts of a conventional filling valve assembly, so that bypass conduit  140  may be connected to conventional air replenishing apparatus (not shown). To this end, cheek valve  144  has a projection  152  enabling depression of check valve  144  when an air chuck is fitted to bypass conduit  140 . Threads  154  enable a threaded cap (not shown) to be attached to upper end  150  to protect check valve  144  and its seat  146  from contamination. Passageway  142  opens to air passage  124  so that freshly introduced pressurized gas both fills the tire and also acts on indicating member  130 . 
     Thus far, the invention has been described in terms of being connected to a conventional filling valve assembly. In another embodiment of the invention, referring now to FIG. 3, novel indicator  210  is configured to supersede the conventional filling valve entirely, being fitted to a metallic wheel in place of the conventional filling valve assembly. Indicator  210  includes the functional components of, selectively, indicator  10  and  110 , and further includes a resilient bulb  260  bearing a groove  262 . Bulb  260  is dimensioned and configured to seat within an opening (not shown) formed in conventional wheels for receiving conventional filling valve assemblies. Bulb  260  and groove  262  collectively provide structure connecting housing  212  directly to the wheel (not shown) on which the tire is mounted. In the embodiment of FIG. 3, the connecting structure cooperates with the wheel both to mount indicator  210  securely to the wheel and also to establish an air passage establishing pneumatic communication between said inner chamber and air generating pressure within the tire. 
     FIG. 4 illustrates a further embodiment of the indicator of the present invention, indicated generally at  410 . The indicator  410  generally includes a body  412  with a coupling chamber  414  formed in one end and a coupling nozzle  416  formed in an opposed end. A viewing window  418  defining an inner chamber  420  between the window  418  and the body  412  is positioned at an intermediate point along the body between its opposite ends. A flexible, resilient bladder  421  is positioned in the inner chamber  420  within a center cavity indicated by  422 , formed within the body  412 , and generally being connected to the coupling member  414  and the coupling nozzle  416 . Optionally, a cap  424  can be applied to the body  412  over the coupling nozzle  416 . 
     The body  412  generally is built from a durable plastic material such as a polycarbonate or similar material. The viewing window  418  is preferably made from a semitransparent plastic material and enables a visual inspection of the bladder  421  from the exterior of the body  412 . The flexible bladder  421  acts as an indicating member and generally is made from a resilient, inflatable material so as to expand as pressurized air/gas from the tire is applied thereto. The bladder generally is out of contact with the viewing window  418  when not inflated, but as pressure is applied from the tire, the flexible bladder  421  is inflated and will expand into engagement contact with the viewing window  418 . 
     The flexible bladder  421  further generally is colored with a predetermined hue, i.e. green, blue, etc. The coupling member  414  further has a projection  426  that is threaded internally to receive a standard filler valve (not shown). The coupling nozzle  416  also typically is threaded externally to receive compressed gas supply or additional pressure measuring devices (not shown) connected thereto. The center cavity  422  is fitted with a commercially available valve core  428  to support a standard interface to a compressed gas supply or pressure measuring devices through the coupling nozzle  416 . The center cavity  422  connects to the coupling member  414  through a plurality of air passages  430  and to the inner chamber  420  through an air channel  432 . 
     When the indicator  410  is coupled onto a filler valve (not shown) through the coupling member  414 , projection  426  depresses the internal valve (not shown) and allows compressed air to flow into the center cavity  422  through air passages  430 . The compressed air flows through the channel  432 , inflating the bladder  421  to a selected or predetermined pressure. As this pressure is reached, the bladder  421  is inflated and expands into engaging contact with the viewing window  418 . The predetermined hue of the bladder  421  enables the bladder to become clearly visible through the viewing window  418  once it has been inflated into contact with the viewing window  418 . If the air pressure is not sufficient, the bladder  421  will not be fully expanded/moved into contact with the viewing window  418 , and thus will not be clearly visible through the viewing window  418 . The refilling of an air chamber such as a pneumatic tire thus can be accomplished without removing the indicator  410  from the valve, simply by removing the cap  424  and connecting a compressed air supply onto the coupling nozzle  416 . 
     FIG. 5 illustrates still a further embodiment of the indicator  510  that is configured to fit to a metallic wheel in place of the conventional filling valve assembly. The indicator  510  generally includes the functional components of, selectively, indicator  10 ,  110  and  410 , and further includes a resilient bulb  515  having a groove  517 . The bulb  515  is dimensioned and configured to seat within an opening (not shown) formed in conventional wheels for receiving conventional filling valve assemblies. Bulb  515  and groove  517  collectively provide a structure for connecting housing  513  directly to the wheel (not shown) on which the tire is mounted. In the embodiment of FIG. 5, the connecting structure cooperates with the wheel both to mount the indicator  510  securely to the wheel and also to define an air passage for establishing pneumatic communication between said inner chamber and air generating pressure within the tire. 
     The present invention is susceptible to modifications and variations, which may be introduced without departing from the inventive concept. For example, threads  20 , 120  or the coupling member  414  securing indicator  10 ,  110  or  410  to the filling valve assembly may be modified to enable manual connection to the wheel in another manner, so long as manual connection and removal is enabled. The invention may be modified to attach directly to the tire or to an inner tube (not shown) associated with the tire. For example, the invention may be fabricated integrally with tires and rubber tubes, if desired. 
     It is also understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.