Abstract:
This is an invention for a system and method of automatically inflating the wheels of a vehicle during driving operation. When air pressure in a wheel of the vehicle decreases below a pre-determined limit, a solenoid device is activated to extend a kick-rod. As the wheel rotates, a pump mounted on the wheel strikes the kick-rod of the solenoid device, thereby causing air to be injected into the wheel. The automatic tire inflation system works by employing the mechanical energy of the rotating wheel to drive the pump upon contact with the solenoid device.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of U.S. Ser. No. 12/804,589 filed Jul. 26, 2010 now abandoned. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to a system and method for tire inflation and, more particularly, to a system and method for automatically maintaining pressure in vehicular tires during operation. 
     BACKGROUND OF THE INVENTION 
     It is well known that driving on underinflated tires can adversely affect a vehicle&#39;s performance, and thus it is a primary safety concern. According to a report by the Department of Transportation&#39;s National Highway Traffic Safety Administration, more than a quarter of automobiles and light trucks in United States have one or more tires underinflated below the level recommended by the vehicle manufacturer. Vehicles with underinflated tires have been shown to have handling problems that result in significant numbers of highway fatalities and injuries. Under-inflation is also a primary cause of early tire breakdown and poor tread life, which shortens tire life, resulting in increased maintenance costs. In addition to contributing to safety hazards and maintenance costs, it has also been shown that driving on underinflated tires can significantly decrease fuel economy. Therefore, the proper monitoring and regulation of tire pressure can increase tire life, reduce fuel consumption, and improved handling and ultimate safety. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an automatic tire inflation system to properly maintain tire pressure. 
     It is a further object of the present invention to provide a tire inflation system that does not require an operator to manually inflate the tire. 
     It is a further object of the present invention to provide a tire inflation system that automatically inflates the tire during operation. 
     In accordance with the objects of the invention, an automatic tire inflation system is comprised of a system of sensors that are connected to a pressure-monitoring device, which communicates with an electronic controller to activate electric solenoid devices that, in turn, actuate pumps affixed to the wheels of a vehicle. 
     Each wheel of the vehicle is provided with a pump. The commercial name of the pump will be known as JAMM pump, which does not refer to any specific function of the device. The pump is inserted into the wheel such that it rotates with the tire during operation. When air pressure in any one of the vehicle&#39;s four tires falls below a pre-determined limit as determined by sensors connected to the wheels, a pressure-monitoring device transmits the information to an electronic controller. The electronic controller activates a corresponding solenoid device associated with that wheel. The activation of the solenoid device causes it to extend a kick-rod. As the pump rotates with the wheel during operation, it strikes the extended kick-rod, causing the pump to compress, thereby injecting air into the tire. In this way, the mechanical energy of the rotating wheel is used to drive the pump upon contact with the solenoid kick-rod. Thus, with each revolution of the wheel, the pump functions to inject a burst of air into the tire. This process is repeated with each revolution of the wheel until the tire is inflated to an acceptable level. 
     More particularly, the pump is comprised of a piston movably connected to a valve body. The pump operates as the piston to effect an intake stroke and a compression stroke. On the intake stroke, the piston is actuated by contact with the solenoid kick-rod to draw outside air into an intake chamber in the valve body of the pump. On the compression stroke after contact with the solenoid kick-rod, the piston is pushed by an internal spring in the valve body into a closed position to seal the intake chamber. As the piston returns to the closed position, the air inside the intake chamber is compressed into a compression chamber inside the piston, where it is forced through a needle valve and into the cavity of the tire. Since the pump strikes the extended kick-rod once with each revolution of the wheel, the pump undergoes one cycle of intake stroke and compression stroke during each revolution. Hence, each revolution of the wheel results in an injection of air into the tire. This is repeated until the tire is inflated to an acceptable level as determined by a sensor. Once the tire is properly inflated, the pressure-monitor communicates with the electronic controller to cease activation of the solenoid device, thus concluding the process. 
     This and other advantages of the present invention will become apparent from a reading of the following description of the preferred embodiments taken in connection with the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of selected components of a model vehicle having an automatic tire inflation system according to the present invention. 
         FIG. 2  is a schematic of the system of sensors, monitoring device, electronic controller, digital panel, solenoid devices, and pumps. 
         FIG. 3  is a partial breakout side view of a wheel showing the positioning of the pump and the solenoid device. 
         FIG. 4  is a front sectional view of a wheel showing the positioning of the pump and the solenoid device. 
         FIG. 5  is an exploded view of the pump. 
         FIG. 6   a  is a front view of an embodiment of the pump. 
         FIG. 6   b  is a front sectional view of an embodiment of the pump. 
         FIG. 7  is a front view of another embodiment of the pump. 
         FIG. 8   a  is a partial view of the solenoid device in the inactivated state in relation to an embodiment of the pump. 
         FIG. 8   b  is a partial view of the solenoid device in the activated state in relation to an embodiment of the pump. 
         FIG. 8   c  is a partial view of the solenoid device in contact with the pump. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows an automatic tire inflation system  1  according to the present invention for a prototypical vehicle  10  having four wheels  20 . While the invention is described in reference to four-wheeled vehicles (e.g. cars, trucks, utility vehicles), the tire inflation system  1  of the present invention can be applied to two-wheeled vehicles (e.g. motorcycles) and three-wheeled vehicles (e.g. all-terrain vehicles) as well. 
     The automatic tire inflation system  1  includes a sensor  30  of a type well-known in the art for measuring the air pressure of wheel  20 . In a preferred embodiment of the invention, four sensors  30  measure the pressure in each of the four wheels  20 . Though the sensors  30  of this embodiment are direct sensors that monitor the actual pressure of wheels  20 , it is within the contemplation of the invention to employ indirect sensors that can measure the rotational speeds of wheels  20  to determine the “apparent” air pressure of wheels  20 . 
     As shown in the schematic of  FIG. 2 , each of the four remote sensors  30  communicates information to a pressure-monitoring device  40 . The pressure-monitoring device  40  is connected to an electronic controller  50 . In the preferred embodiment, electronic controller  50  communicates with a programmable digital panel  60  in the vehicle to display the air pressure information to the driver. 
     If the air pressure in any of the four wheels  20  falls below a preset level, electronic controller  50  activates a corresponding solenoid device  70  associated with the underinflated wheel. As shown in  FIG. 3 , a solenoid device  70  is mounted in proximity to each wheel  20 . In the preferred embodiment as shown in  FIG. 4 , solenoid device  70  can be mounted on a brake assembly or other suitable location to function for the intended purpose as described herein. Each solenoid device  70  has a kick-rod  72  that extends upon activation. Kick-rod  72  can be maintained in the extended position until electronic controller  50  deactivates solenoid device  70  to retract kick-rod  72 . Or, alternatively, kick-rod  72  can automatically retract after each extension. 
     The activation of solenoid device  70  causes kick-rod  72  to extend to contact a pump  100  mounted on wheel  20 . As shown in  FIG. 4 , pump  100  is affixed in a wall  24  of wheel  20 . It is preferably affixed to the base of the wheel  20 , adjacent to where the tire sits against the rim. Further, pump  100  is preferably located diametrically opposite of air valve  12  as shown in  FIG. 4  in order to counterbalance air valve  12 . Pump  100  is affixed in wall  24  by an elastomeric seal  110 , a top washer  120 , and a retainer nut  130 . Alternatively, pump  100  can be affixed by a grommet (not shown) or other common methods known in the art. 
     Pump  100  has a valve body  140  that is inserted into wall  24  of tire  22 . As shown in  FIG. 5 , valve body  140  is cylindrical, having an internal end  142 , an external end  144 , and walls  146  that define an intake chamber  148 . 
     Valve body  140  is inserted into tire  22  with internal end  142  oriented towards the inside of tire  22  and external end  144  oriented towards the outside of tire  22 . Valve body  140  has a plurality of intake ports  150  on external end  144  for drawing ambient air into intake chamber  148 . In the preferred embodiment, four intake ports  150  are symmetrically located on external end  144 . 
     Referring now to  FIGS. 6   a  and  6   b , a piston  160  is moveably connected to valve body  140 . Piston  160  is comprised of plunger  170  and rod  180 . 
     Plunger  170  is located in intake chamber  148  of valve body  140 . Plunger  170  has compression chamber  172  that communicates with intake chamber  148  via transition ports  174 . 
     An elastomeric flat seal  176  is mounted on plunger  170 . Elastomeric flat seal  176  is interposed between intake ports  150  and transition ports  174 , such that elastomeric flat seal  176  functions to close intake ports  150  when piston  160  is inactive. Plunger  170  also has flange  176  that is interposed between transition ports  174  and internal end  142  of valve body  140 . Flange  178  has a concave edge  179  to accommodate an o-ring  190 , which forms a seal against the inside wall of intake chamber  148 . Flange  178  abuts against a spring  200 , which sits between flange  178  and a retainer ring  210  that is affixed to internal end  142  of valve body  140 . A standard needle valve  220  is connected to plunger  170  for communicating with the inside cavity of tire  22 . 
     Rod  180 , which extends outside of valve body  140 , has a distal end  182 . Distal end  182  can be rounded, as shown in  FIG. 6   a , or beveled, as shown in  FIG. 7 , or of any other such shape that upon contact with kick-rod  72  it travels as shown in  FIGS. 8   a - c.    
     When air pressure in wheel  20  decreases below a pre-determined level, pressure-monitoring device  40  signals electronic controller  50  to activate solenoid device  70 . Upon activation, solenoid device  70  extends kick-rod  72  as shown in  FIG. 8   b . When extended, kick-rod  70  strikes distal end  182  of piston  160  with each revolution of wheel  20 , causing piston  160  to be depressed as shown in  FIG. 8   c . Kick-rod  72  can be maintained in the extended position such that it continually strikes piston  160  with each revolution until tire  22  is inflated. When tire  22  is properly inflated, electronic controller  50  deactivates solenoid device  70 , thereby retracting kick-rod  72 . Alternatively, kick-rod  72  can automatically retract after each extension, such that electronic controller  50  must activate solenoid device  70  for each revolution of wheel  20  until tire  22  is inflated. 
     The depression of piston  160  draws outside air in through intake ports  150 . The negative pressure created in intake chamber  148  by depression of piston  160  causes elastomeric flat seal  176  to flex as shown in  FIG. 8   c , allowing the drawn air to enter intake chamber  148 . After contact with solenoid device  70 , spring  200  urges piston  160  to the closed position by pushing the elastomeric flat seal  176  against the intake ports  150  to effectively seal intake chamber  148 . 
     As piston  160  returns to the closed position, the air inside intake chamber  148  passes through transition ports  174  to enter compression chamber  172 , where it is it is forced through needle valve  220  and into the cavity of tire  22 , thereby inflating wheel  20 . The process is repeated with each revolution of wheel  20  until the air pressure reaches an acceptable pre-determined level. When wheel  20  is properly inflated as determined by sensor  30  and pressure-monitor  40 , electronic controller  50  ceases to activate solenoid device  70 , thus concluding the process. 
     While the invention has been described in reference to certain preferred embodiments thereof, it is to be understood that that the foregoing description is not intended to limit the invention to those embodiments. Reasonable variation and modification are possible within the scope of the foregoing disclosure and drawings without departing from the spirit of the invention, which is defined by the appended claims.