Abstract:
Small air pumping devices are mounted directly in the conventional tire valves to keep the vehicle&#39;s tires properly inflated without requiring the user&#39;s attention. If a tire is beginning to become under-inflated, a pumping piston having a single check valve is moved reciprocally in the tire valve stem by the cyclical deformation of the tire during the vehicle&#39;s travelling. The ambient air is pumped into the tires through the tire valves. The tire valves incorporating the pumping devices are kept using in a regular manner for reliably preventing air escaping from the tires and for inflating the tires from the external sources. Such “self-inflating” tire valves may be mounted as the regular tire valves both in new manufactured vehicles or in used vehicles without any modifications in the vehicle&#39;s axes, wheels or tires and without the necessity to make additional openings in the wheel.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Cross-Reference to Related Applications 
         [0002]    The present application is a continuation-in-part of application Ser. No. 11/979076 filed on Oct. 31, 2007 which is now copending. 
         [0003]    2. Field of the Invention 
         [0004]    This invention relates to methods and apparatus for keeping a vehicle&#39;s tires properly inflated, and more particularly, it pertains to a tire valve including a pumping device which maintains the tire properly inflated by automatically pumping small amounts of ambient air when the tire beginning to become under-inflated. 
         [0005]    3. Technical Background 
         [0006]    Vehicle&#39;s tires are designed to be used at the air pressure specified by the manufactures to optimize the performance and fuel economy, to maximize tire life, and for driving safety. 
         [0007]    However, pneumatic tires can be subject to slow leaks of inflation air. Because of various “natural” sources of leaks, such as permeability of the tire material, not hermetical joints between the tire and rim, etc., the air pressure in a tire can reduce during the vehicle&#39;s operation as much as one psi per month, even without a puncture of the tire by a foreign object such as a nail. It&#39;s for this reason that the air pressure in the tire needs to be checked regularly by vehicle owners and air periodically added from an external sources. 
         [0008]    Advances in technology have resulted in improvement of tire pressure stability under normal operating conditions with negligible air leakage. Hence, operators often tend not to checking air pressure regularly. A survey provided by the National Highway Traffic Safety Administration (NHTSA) shows that only 4% of respondents checked the pressure as part of their routine maintenance. As a result, the under-inflation of tires is considered the most common car problem today. According to this NHTSA, about 30% of all vehicles have at least one tire that is 8 psi or more under-inflated. About 5% have all four tires seriously under-inflated. 
         [0009]    Tire pressure directly impacts fuel efficiency. Under-inflated tires have a higher rolling resistance, this results in increased fuel consumption. Under-inflated tires can cut fuel economy by 2% per pound. For example, if the tires should be at 32 psi and they are actually at 27 psi, the mileage is reduced by 10%. According to the U.S. Department of Energy, under-inflated tires are responsible for nearly 3.3 million gallons of wasted gasoline each and every day. 
         [0010]    The under-inflation of tires also impairs steerability and degrades driving safety. The under-inflated, “soft” tires affect cornering and traction. Furthermore, the reduced footprint results in additional wear of the tires. This not only raises the operational cost of the vehicle but also is very important for safe driving. Hence, maintaining correct air pressure in a vehicle&#39;s tire is very important. 
         [0011]    Prior art pressure maintenance efforts are known focused on different systems for adding small amounts of air while the tire rotates to compensate for losses due to leaks. Numerous tire pressure maintaining system have been invented. For example, U.S. Pat. Nos. 4,269,252 to Shapiro, 4,349,064 to Booth, 4,840,212 to Wei, 5,355,924 to Olney, 5,556,489 to Curlett et al., 5,558,730 to Olney, 5,975,174 to Loewe, 7,013,931 to Toit, 7,117,731 to Hrabal disclose various types of air pumps disposed within the tire. Unfortunately, such devices have a limited practical usage. An important reason of that is a necessity of considerable changes in the design of the wheels, tires, tire inlet valves, etc. or/and to provide openings and valves in addition to the conventional tire inlet valves, such as Schruder type or Presta type, which are proved to be reliable for many years of using. Any additional openings in the vehicle&#39;s rim with the valves that are supposed to be used not only for preventing the air escaping from the tire but also for pumping the air into the tire can reduce the reliability of the system. Furthermore, most of the prior art air pumping systems are too complex to be workable. 
         [0012]    This invention seeks to overcome the deficiencies of the known tire pressure maintenance systems and benefit from the advantages that may be expected from the knew method and apparatus. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    The principal objects of the present invention is to reduce fuel consumption, tire wearing and to improve driving safety of a vehicle by keeping the tires fully inflated at a correct pressure at all times without requiring the user&#39;s attention. This has to be achieved by using a new type of tire valves which are not only used for inflating the tire from the external sources and for preventing air escaping from the tire, but also keep the tires properly inflated during the vehicle&#39;s operation. 
         [0014]    When the tire is beginning to become under-inflated, the ambient air is pumping into its interior by a small pumping device which is mounted directly into the standard tire valve having a conventional tire valve core. The devices includes a piston with a single check valve and is operated during the movement of the vehicle by the cyclical deformations of the tire only if the tires are under-inflated. A lever system serves as means for transferring such a cyclical tire deformation to the reciprocating piston in the pumping device. Each time when the portion of such a tire incorporating the tire valve is deformed by the vehicle&#39;s weight against the road surface, the piston is moved in the cylindrical bore of the valve stem against the force of a compression spring. After contacting this part of the tire with the road, the tire shape is restored and the piston is pushed back by the spring. 
         [0015]    During the piston&#39;s reciprocating movement, the valve actuator can be engaged or disengaged with the piston, so that the valve core can be opened when that reciprocating movement can exceed a predetermined limit if the tire is under-inflated. During the intake stroke, the ambient air is drawn into a cylindrical bore, made in the tire valve stem body. 
         [0016]    During the compression stroke, the air is compressed by the compression spring after the valve core is closed and is expelled into the tire interior. It happens during each rotation of the wheel only if the tire is under-inflated and the vehicle accelerates a sufficient speed. 
         [0017]    In the preferred embodiment of the invention, the levers are automatically pivoted in a safety position, so that they can not be broken or to damage the tire in the case of an accident when the tire is flattened. 
         [0018]    The present self-inflating tire valve can be incorporated not only into new manufactured vehicles but also into existing vehicles without necessity of modification of axles, wheels, or tires and without making any additional openings in the wheel for pumping the air into the tire. 
         [0019]    The embodiment shown in the accompanying drawings is illustrative only. Attention being called to the fact that changes may be made in the specific construction while yet remaining within the scope of the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0020]    FIG.  1 ′ is a cross-sectional view of a vehicle&#39;s wheel with a tire valve in accordance with the preferred embodiment of the invention. 
           [0021]    FIG.  2 ′ is an enlarged cross-sectional view of the tire valve and the lever system shown in  FIG. 1 . 
           [0022]    FIG.  3 ′ is a cross-sectional view taken along line III-III in FIG.  2 ′. 
           [0023]    FIG.  4 ′ is the same view of the preferred embodiment of the invention as shown in FIG.  1 ′ when the tire is under-inflated and the part of the tire incorporating the tire valve is deformed being in contact with the road while the vehicle is traveling with a preselected speed. 
           [0024]    FIG.  5 ′ is a cross-sectional view of a vehicle&#39;s wheel with a tire valve in accordance with an alternative modification of the preferred embodiment of the invention. 
           [0025]    FIG.  6 ′ is the same view of the alternative modification of the preferred embodiment of the invention shown in FIG.  5 ′ when the tire is under-inflated and the part of the tire incorporating the tire valve is deformed being in contact with the road while the vehicle is traveling with a preselected speed. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    A tire valve incorporated with the pumping device for automatically maintaining the tire inflation in a vehicle&#39;s wheels will become apparent from the following description taken in conjunction with presently preferred embodiment thereof with reference to the accompanying drawings. The identical details in all the drawings have the same designations. 
         [0027]    Turning to FIGS.  1 ′- 4 ′, the preferred embodiment of the invented tire valve includes a conventional valve core  10 , such as a Schruder type, disposed within a valve stem  11  which is mounted on the wheel rim  12 . The valve core  10  includes a seal  13 , a spring  14  and a valve actuator  15 . The outer end  15   a  of the actuator is supposed to be pressed by a consumer to open the tire valve for inflating the tire from an external source (not shown). The tire valve is fixed to the wheel&#39;s rim  12  together with a bracket  16  by a nut  17  through the sealing rings  18  and  19 . 
         [0028]    The valve stem  11  is provided with a cylindrical bore  20  wherein a piston  21  is slidably mounted. The piston  21  includes at least one sealing o-ring  22  and a check valve  23  having a spring  24  which can be adjusted by a screw  25 . There is a stopper  26  on the inner end of the valve actuator  15  which is disposed inside of an axial channel  27  in the piston  21 . Because the size of the opening  28  at the end of the piston  21  is smaller than the diameter of the axial channel  27 , the piston  21  can be moved along the central axis in the cylindrical bore  20  without engaging with the valve actuator  15  until the stopper  26  reaches to the end of the axial channel  27 . After that the valve actuator  15  will be engaged by the piston  21  and pulled to open the valve core  10 . Any means such as spring latches, threads, special configurations of the stopper  26  and opening  28 , elastic material etc. can be used for penetrating of the stopper  26  into the axial channel  27  during assembling of the tire valve and for preventing the stopper  26  from going out of the axial channel  27  through the opening  28  during the valve operation. 
         [0029]    A tire valve cap  29  is provided with holes  30  which are small enough to block road grit and particles but large enough to allow the ambient air to pass into the valve stem  11 . There is an opening  31  in the piston&#39;s body for air communication between the check valve  23  an the tire interior. The piston  21  has a circular rib  32  which is pressed by a compression spring  33 . The other end of the spring  33  is biased against the support  34  which is fixed in the bracket  16 . There is another ring  35  on the end of the piston  21  which can be pressed by the forked end of the the lever  36  pivotally mounted on the axis  37  in the bracket  16 . 
         [0030]    A push rod  38  is pivotally mounted on the axis  39  which is fixes on the other forked end of the lever  36 . A torsional spring  40  causes the push rod  38  to be pivoted around the axis  39  clockwise into a position shown in FIG.  1 ′ in dotted lines. When the wheel&#39;s rotation exceeds a predetermined speed the push rod  38  is pivoted by the centrifugal force into a substantially radial position relative to the wheel, as shown in FIG.  1 ′ in solid lines. A weight  41  can be disposed on the end of the push rod  38 . When the tire is inflated properly, there is a gap  42  between the radially oriented push rod  37  and the inner peripheral tire surface  43 . The piston  21 , the bracket  16 , the lever  36  and the push rod  38  can be made from various materials such as metals or plastics. 
         [0031]    During the vehicle&#39;s travelling, each time when the portion of the tire incorporating the tire valve comes into contact with the road it is deformed by the vehicle&#39;s weight. If the tire is inflated properly, as shown in FIG.  1 ′, the tire deformation is not enough to overcome the gap  42  and to press the push rod  38  by the peripheral surface  43  even if the push rod  38  is oriented radially. If the tire is under-inflated and the vehicle is traveling with a sufficient speed, the inner peripheral tire surface press the push rod  38 , as shown in FIG.  4 ′. The lever  36  is pivoted around the axis  37  counter-clockwise by the upper end of the push rod  38 . As a result, the piston  21  is moved by the forked end of the lever  36  in the cylindrical bore  20  from the position shown in FIG.  1 ′ to the position shown in FIG.  4 ′ against the force of the compression spring  33 . The air pressure in the cylindrical bore  20  is reduced until the tire valve core  10  and the check valve  23  are kept closed. At the end of the piston&#39;s movement, the valve activator  15  is pulled by the stopper  36  to open the valve core  10 . The ambient air is drawn through the holes  30  in the cap  29  and through the open seal  13  of the valve core  10  into the cylindrical bore  20 . 
         [0032]    A stopper  45  restricts the movement of the push rod  38  after the valve core  10  is opened. When the safety pin  44  presses the stopper  45  the push rod  38  is declined from the radial position. 
         [0033]    After contacting with the road, the deformed part of the tire restores its shape. As a result, the piston  21  is pushed back to the position shown in FIG.  1 ′ by the compression spring  33 . This backward movement of the piston  21  can occur during the period of the wheel rotation before the next contact of this tire part with the road. At the beginning of this movement the valve core  10  is closed and after that the air in the cylindrical bore  20  is compressed and expelled through the check valve  23  into the tire interior when the pressure in the cylindrical bore  20  exceeds the air pressure in the tire. 
         [0034]    While the vehicle keeps traveling, these movements of the piston  21  are repeated each time when the tire portion incorporating the tire valve is in contact with the road, so that the ambient air is successively drawn into the cylindrical bore  20  through the valve core  10  and expelled through the check valve  23  into the tire interior until it is inflated properly. 
         [0035]    Each intake stroke of the piston  21  is driven by the tire deformation and consists of two successive steps. During the first step, the valve core  10  and the check valve  23  are closed. As a result, the pressure in the cylindrical bore  20  is reduced. During the second step, the cylindrical bore  20  is filled with the ambient air through the opened seal  13  of the valve core  10 . 
         [0036]    Each compression stroke, which is driven by the force of the compression spring  23 , also consists of two successive steps. During the first step, the valve core  10  is being closed. This step should be as short as possible to reduce escaping the air from the cylindrical bore  20  through the valve core  10  before it is closed. During the second step, the air is compressed in the cylindrical bore  20  and is expelled into the tire interior through the check valve  23 . 
         [0037]    Because the tire valve core  10  remains open for a short period when the ambient air is drawn into the tire valve during the intake stroke when the check valve  21  is closed, reliability of the conventional tire valve for preventing air escaping from the tire can not be reduced. 
         [0038]    The valve core  10  can be opened only if the tire is under-inflated and the vehicle is accelerated to a sufficient speed for developing the centrifugal force which can pivot the push rod  38  against the force of the torsional spring  40  to the radial position. 
         [0039]    If the vehicle is stopped or is moving with a low speed the push rod  38  is pivoted by the torsional spring  40  in a position shown in FIG.  1 ′ in dotted lines, so that the push rod  38  can not be pressed by the deformed inner peripheral tire surface. The valve core  10  remains closed even if the tire is under-inflated and the tire portion incorporating the tire valve is in contact with the road. 
         [0040]    If the tire is flattened as a result of an accident, the push rod  38  is pivoted clockwise by the deflating tire into a substantially horizontal position. In this position, it can not be broken or cause a damaging to the tire. During the reinflation of the repaired tire, the push rod  38  is automatically pivoted into the operating position. 
         [0041]    The tire valve can be opened for inflating the tire from an external source in a regular manner by pressing the outer end  15   a  of the valve actuator  15 . In this case, the check valve  23  is also opened either directly by the inner end of the actuator  15  or by the high air pressure developed by the external source of the tire inflation. 
         [0042]    In an alternative modification of the preferred embodiment of the invention, shown in FIGS.  5 ′ and  6 ′, the diameter of the extension  15   b  of the actuator  15  is substantially close to the diameter of the axial channel  27  in the piston  21 . Therefore during the compression stroke of the piston  21 , the air is expelled into the tire not only from the cylindrical bore  20  in the valve stem  11  but also from the axial channel  27  in the piston  21 . During the assembling of the tire valve, a screw  46  can be screwed in the end of the actuator extension  15   b  so that the head of the screw  46  (or a washer between the screw and the actuator extension  15   b ) could serve as a stopper  26  for engaging the actuator  15  by the moving piston  21  and opening the valve core  10 . 
         [0043]    The adjusting screw  25  in the piston  21  has an axial bore  47  wherein a flexible cable (or optionally a solid pivotable link)  48  is disposed. One end of the cable  48  is fixed at the inner end of the screw  25 , the other end of the cable  48  is fixed to the lever  36 . When the push rod  38  is pushed up by the deformed tire, the lever  36  is pivoted around the axis  37  and pulls the cable  48 . As a result, the piston  21  is moved from the position shown in FIG.  5 ′ into the position shown in FIG.  6 ′ against the force of the spring  33 . During the compression stroke, the lever  36  is pulled by the cable  48  and is pivoted back into the position of FIG.  5 ′. A shoe  49  is screwed on the end of the push rod  38  so that the length of the push rod  38  can be adjusted and fixed by a nut  50 . 
         [0044]    While this invention has been described with reference to the structure disclosed herein, it is merely exemplary. The preferred embodiment of the present invention is described herein in details to thereby better enable others skilled in the art to utilize this invention. They are subject to many different variations in structure, design, application and methodology. It is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense. For example, various systems and mechanisms can be used for opening and closing the tire valve core by acting of the reciprocating elements of the air pumping means. The invention is intended to cover any modifications, which may be variously practiced within the scope of the following claims or their legal equivalents, rather than by examples given.