Abstract:
A pressure system for monitoring the pressure in tires and other pressurized devices, is mounted in a position to receive pressure. A tire monitoring device structure is provided in which an average user can attach to the tire pressure stem. Internal pressure is monitored and transmitted to a receiver which is programmable to receive the signal and utilize it to provide information and warnings to the vehicle operator should the tire pressure (1) attain a value outside tolerance limits, or (2) become unmatched beyond relative tolerance limits.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a convenient, simple to install tire pressure monitoring system, and more particularly to a valve stem mounted tire pressure sensing and transmission structure with extremely low power consumption.  
       BACKGROUND OF THE INVENTION  
       [0002]     A number of tire pressure systems are known, most of which have a highly integrated dependence upon the vehicle in which they were installed. Sensors and transmitters which are mounted at the inside of car frames require inclusion with the original automobile frame when the automobile is manufactured, or extensive mounting, calibration and specialized labor cost.  
       SUMMARY OF THE INVENTION  
       [0003]     A pressure system for monitoring the pressure in tires and other pressurized devices, is mounted in a position to receive pressure. A tire monitoring device structure is provided in which an average user can attach to the tire pressure stem. Internal pressure is monitored and transmitted to a receiver which is programmable to receive the signal and utilize it to provide information and warnings to the vehicle operator should the tire pressure (1) attain a value outside tolerance limits, or (2) become unmatched beyond relative tolerance limits.  
         [0004]     The device for measuring a single tire pressure is threadably attached on the valve stem of a user&#39;s tire a mechanical pressure gauge on the apparatus is used to sense the pressure inside the tire. A receiver&#39;s display can enable the user to get an instant overall view of the status of the tires, as well as to give the user the ability to predict the need for periodic maintenance and pressure adjustment. A change of tire or replacement of the pressure sensing and transmitting unit can be accompanied by the re-start of a mileage counter, either internal or in the receiver.  
         [0005]     The power consumption for the sensor and transmitters has been brought to a level sufficiently low that batteries need never be changed or that batteries are eliminated. A hybrid version which utilizes batteries as a power storage reservoir is also preferable.  
         [0006]     Power for the device can be provided by battery or by other power generation and storage structure, or by a combination of both. The tire environment includes external exposure, motion and vibration, and power generation sources can include solar, vibration, centripetal, and wind movement.  
         [0007]     Where absolute minimum cost is desired, as well as only an indication of tire pressure falling below an absolute minimum, an arrangement where the magnitude of air pressure pushing against an object, which may include a plunger compressing a spring, or a more direct pressure measuring component. In the case of a plunger, a mechanical switch may be placed underneath a plunger which rises against a spring when sufficient tire pressure is present. Where the tire pressure drops, the plunger is guided by the spring to trip a switch.  
         [0008]     Most versions will depress the valve stem main pressure admittance pin, in order to admit pressurized air into fluid contact with the pressure transmitter. The attachment should be sufficient to hold the pressure and prevent its leaking to the environment, and thus the internal threads will be sufficiently strong and sealing surfaces will have sufficient surface area to hold the pressure. To add pressure to a tire having the pressure transmitter described herein, the tire pressure transmitter is simply threadably removed, the tire filled and then the tire pressure transmitter is replaced. In terms of orientation and style, the pressure transmitter will appear to the essentially the same as a valve stem cap. This will prevent vandalism and theft as tire valve stem caps are rarely disturbed by vandals and thieves.  
         [0009]     Other embodiments may include a separate upper valve so that the tire pressure transmitter will provide an air pressurization inlet and will, in fact, operate as a valve extension.  
         [0010]     A central receiver receives a signal from each transmitter which is coded in accord with its position on the vehicle. The pressure transmitter may be numbered to help the user install the tire pressure monitor on the correct tire which should relate to any schematic of the tire location seen on the monitor. An alarm system can include beeps or other audible warnings of tire pressure outside the normal threshold. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The invention, its configuration, construction, and operation will be best further described in the following detailed description, taken in conjunction with the accompanying drawings in which:  
         [0012]      FIG. 1  is a perspective view of one embodiment of a rudimentary tire pressure sensor which uses a diaphragm actuated switch to indicate a tire under-pressure condition;  
         [0013]      FIG. 2  is a perspective view from the other side of the rudimentary tire pressure sensor seen in  FIG. 1 ;  
         [0014]      FIG. 3  is an exploded view of the components contained within the main mechanical barrel section of the sensor seen in  FIGS. 1 and 2 ;  
         [0015]      FIG. 4  is a bottom view of the electronics housing support seen in  FIGS. 1 and 2 ;  
         [0016]      FIG. 5  is a first side view of the electronics housing support seen in  FIGS. 1, 2 , and  4 ;  
         [0017]      FIG. 6  is a second side view of the electronics housing support seen in  FIGS. 1, 2 ,  3 , and  4 ;  
         [0018]      FIG. 7  is a bottom view of an electronics housing cover which interfits with the electronics housing support seen in  FIGS. 4, 5 , and  6 ;  
         [0019]      FIG. 8  is a side view of the electronics housing cover seen in  FIG. 7 ; and  
         [0020]      FIG. 9  is a plan view of a tire counter weight. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]     Referring to  FIG. 1 , a perspective of one possible embodiment of a tire pressure sensor system  19  and including a tire pressure sensor  21  is seen. The tire pressure sensor  21  has two main parts, a mechanical barrel assembly  23  and an electronics housing section  25 . The mechanical barrel assembly  23  has an open end  27  having an internally threaded surface  29  for engaging the externally disposed threads of a conventional tire pressure valve.  
         [0022]     Some components can be seen in the electronics housing section  25 , including a battery  33 , which may be a commercially available battery  33  having a serial number CR1025.  
         [0023]     A printed circuit board  35 , is connected to the battery  33  and may include a variety of electronics components. A transducer  37  is electrically connected o the printed circuit board  35 . The layout of the electronics housing section  25  will preferably be about 21 millimeters by 21 millimeters by about 13.5 millimeters high. The axial length of the mechanical barrel assembly  23  is about 15.5 millimeters. This results in an overall assembly which is about 29 millimeters high, but which extends above a conventional tire pressure stem only about 21.5 millimeters. The volume, length and width and weight of tire pressure sensor is important as a sensor should be able to be installed by a consumer onto the tire valve stem, and the addition of weight should not be sufficient to significantly affect the tire&#39;s balance.  
         [0024]     A axial displacement member  39  is partially shown. This member transmits the pressure to the switch by means of axial displacement in the direction of the transducer  37 . In the simplest embodiment, the transducer  37  can be a simple switch which is set to close or open upon a given displacement or pressure. In more complex embodiments, the transducer  37  can have a pressure-displacement characteristic which may be linear or which may be linearized or calibration interpreted by associated circuitry. A wireless transmission chip  41  is in electronic communication with the printed circuit board  35  and communicates with a receiver  43 .  
         [0025]     Receiver  43  should at minimum have a display  45  with a minimum number of buttons  47  for either programming or for selection of which of the tire pressure sensors  21  characteristics are be displayed. Receiver  45  should have an antenna  49  compatible with any transmissive structure of the transmission chip  41 .  
         [0026]     Also seen in  FIG. 1  are details of the housing  25 . A base  55  interfits with a cover  57 . The cover is slightly seen as being connected to mechanical barrel assembly  23  via an annular projection  59  which is continuous with the base  55 . The cover  57  may have a number of internal projections including a first projection  61  which is seen as providing some boundary for the battery  33 . A base member  63  extends from the base  55  and further helps to support the battery  33 . The remaining support for the battery  33  is seen in the broad side surface of the cover  57  and a top surface. Referring to  FIG. 2 , a view of the tire pressure sensor  21  seen from the opposite view illustrates a more complete rendering of the structures seen in  FIG. 1 .  
         [0027]     Referring to  FIG. 3 , an exploded view of the mechanical barrel assembly  23  seen in  FIGS. 1 and 2  is seen. At the top is a pressure washer  67  having a through bore  69  and a circumferentially more outwardly located portion  71  with respect to a circumferentially more inwardly located portion  73  which will fit through an aperture  75  in a wall  77  within the mechanical barrel assembly  23 . Pressure washer  67  helps to seal with respect to a conventional tire pressure fitting and to insure that the pressure from a tire which is to be measured travels through the center of the pressure washer  67  and does not leak through the space adjacent the threads  29  and cause eventual deflation of the tires.  
         [0028]     On the other side of the wall  77  and extending partially through the aperture  75  is a pressure pin  81  having a pressure pin projection  83  and a round support plate  85 . The round support plate  85  carries a pressure aperture  87 . The pressure pin projection extends through the aperture  75  and the bore  69  to both come into contact with and urge a conventional tire valve pressure valve pin to admit pressurized air into the mechanical barrel assembly  23  so that it can be sensed by the tire pressure sensor  21 .  
         [0029]     Next seen in  FIG. 3  is a pressure displacement diaphragm  91 . Pressure displacement diaphragm  91  serves to transmit a mechanical indication of pressure, but without allowing air flow beyond the pressure displacement diaphragm  91 . Pressure displacement diaphragm  91  has a relatively thicker peripheral wall  93  continuous with a circumferentially angled membrane  95 , which has a general “W” shape as seen in cross section in  FIG. 3 . The center of the membrane  95  has a flat area  97 . The diameter of the relatively thicker peripheral wall  93  may preferably exceed an internal diameter of a surface  99  seen in mechanical barrel assembly  23  so that the pressure displacement diaphragm  91  forms a good tight fit within the mechanical barrel assembly  23  and so that no significant leakage around the pressure displacement diaphragm  91  takes place.  
         [0030]     To provide error free operation, a transducer pushing structure  101  is positioned adjacent the pressure displacement diaphragm  91 . Transducer pushing structure  101  has a first diameter portion  103 . A second diameter portion  105  is sized to effectively abut the transducer  37 . The cross section of first diameter portion  103  reveals an annular projection  107  which has a cross sectional diameter roughly equivalent to the cross sectional diameter of flat area  97  of the membrane  95  of the pressure displacement diaphragm  91 . This insures a well supported and even force movement of the transducer pushing structure  101 .  
         [0031]     Referring to  FIG. 4 , a bottom view of the base  55  of the electronics housing section  25  illustrates the prominent annular projection  59 . In general, the annular projection  59  will be attached to the inside surface  99  of the mechanical barrel assembly  23 . In turn, the second diameter portion  105  of the transducer pushing structure  101  will axially slide within the annular projection  59 . Ideally, the outer diameter of the annular projection  59  will fit snugly within the interior diameter of the mechanical barrel assembly  23  adjacent the inside surface  99 . As such, the face of the annular projection  59  will abut the upper radial surface of the peripheral wall  93  and help to hold the pressure displacement diaphragm  91  securely in place. The second diameter portion  105  of the transducer pushing structure  101  then moves through and has an outer diameter smaller than the inside diameter of the annular projection  59 . Further, because the pressure displacement diaphragm  91  is also a pressure barrier, the electronics housing section  25  will not be otherwise pressure urged out of the mechanical barrel assembly  23 . So long as the pressure displacement diaphragm  91  and annular projection  59  are firmly in place the displacement of the transducer pushing structure  101  will be solely due to the displacement of the membrane  96  within the pressure displacement diaphragm  91 . Also seen in  FIG. 4  are the base member  63  which formed a lower support for the battery  33 . Other spacing structures are seen and also shown in dashed line format including structures  111  and  113 .  
         [0032]     Referring to  FIG. 5 a  plan view of the base  55  is seen. A groove  117  is seen which will be used to make an exact fit with the cover  57 .  FIG. 6  illustrates a plan view from a different angle, with  FIGS. 4, 5 , &amp;  6  illustrating a complete view of the base  55 .  
         [0033]     Referring to  FIG. 7 , a plan view of the cover  57  is seen. The thickness of the cover  57  is indicated by the dashed line about the upper periphery of the top  121  and the sides  123 . At the bottom a chamfer  135  is configured to interfit with the groove  117 . The chamfer extends around the base  55 . Also seen in dashed line format is the first projection  61  previously seen in  FIG. 1 .  
         [0034]     Referring to  FIG. 8 , a view looking into the cover  57  shows that the chamfer  235  extends completely around the inner periphery of the cover  57 . The first projection  61  is seen directly. The structures seen in  FIGS. 4-8  show how a close packed arrangement within the electronics housing section  25  can be provided. Where four of the tire pressure sensors  21  are mounted on the tires of a vehicle, both the mechanical barrel assembly  23  and electronics housing section  25  must be sturdy and able to withstand centrifugal force from the spinning of the tire upon which they are mounted.  
         [0035]     It should be noted that for a conventional tire pressure valve stem which extends directly toward the center of a tire, that the centrifugal force will work to push the transducer pushing structure  101 , the membrane  95  and its flat area  97  in the direction of the tire valve stem. As a result, tire pressure measurement at high speed may produce a reading which is less than the same reading while the car is stopped.  
         [0036]     Another consideration for the tire pressure sensor system  19  tire pressure sensor 21 is weight. The cover  57  is preferably as small as  21  millimeters square or smaller, and about  13  millimeters high. Thus in terms of an overall dimension, the tire pressure sensor system  19  tire pressure sensor  21  is roughly the size of a regulation die. It is preferable that the total weight of each tire pressure sensor  21  is light enough that the tire balance is not affected. Referring to  FIG. 9 , however, depending upon the total weight of the tire pressure sensor  21 , a counterbalancing weight  131  may be provided for mounting on a conventional tire, opposite the location of the pressure valve assembly to provide balance. Because both the tire pressure sensor  21  and the outer mounted counter weight  131  are both located to the outside of the tire, a user would be capable of installing the counter weight  131  opposite the conventional tire pressure valve stem.  
         [0037]     In the case of a larger, heavier tire pressure sensor  21  other structures for more secure mounting can be employed, as well as more substantial counterweights. In any event, the tire pressure sensor system  19  can be provided as a kit which includes four tire pressure sensors  21 , four counter weights  131 , and receiver  43 . Where the tire pressure sensor  21  is of insignificant weight as to affect tire balance, the kit can be provided without the counter weights  131 .  
         [0038]     While the present invention has been described in terms of a tire pressure system, and particularly to a user mounted structure attached to a valve stem in the same manner as a valve stem cap, and which has the ability to derive power from its environs, the present invention may be applied in any situation where user installation is desired to yield a complete and integrated smart tire pressure system.  
         [0039]     Although the invention has been derived with reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. Therefore, included within the patent warranted hereon are all such changes and modifications as may reasonably and properly be included within the scope of this contribution to the art.