Abstract:
An intelligent tire pressure management system capable of real-time tire pressure monitoring, vehicle load detection, and automatic tire inflation and deflation for maintaining optimal tire pressure in a commercial vehicle. Additional functions include counting tire rotations for calculating and recording distance travelled for each tire, and detecting wheel sliding due to locked-up tires. The system includes a chassis-mounted control box connecting to the vehicle air supply, a hubcap-mounted dual wheel valve apparatus integrated with a rotary union assembly that connects through the vehicle hollowed axles to the air tubes from the control box. The inflation/deflation supporting dual wheel valve apparatus has an embedded electronic unit that monitors individual tire pressure and temperature in real time, and communicates with the control box over the power line. Furthermore a load sensor integrated with the control box provides the system with the current vehicle load information. With readily available real time tire pressure data and current vehicle load information, this system can intelligently adjusts tire pressure to the desired level when necessary and, as a result, prolongs tire life, improves fuel economy, reduces the vehicle maintenance costs, and promptly alerts the driver of low, leaky or flat tire conditions for enabling the driver to take immediate corrective actions.

Description:
FIELD OF THE INVENTION 
     The present invention relates to tire pressure management systems with real time pressure monitoring and automatic pressure inflation and deflation functionalities. Particularly, the invention relates to an apparatus intelligently maintaining optimized tire pressure with respect to pressure variations, road conditions, and vehicle load conditions while the vehicle is in motion, plus the counting of tire rotations for measurement of distance traveled and detection of locked wheel situations. 
     BACKGROUND OF THE INVENTION  
     Keeping proper tire pressure is a very important aspect of vehicle maintenance. Driving on underinflated or overinflated tires compromises stopping distance, ride and handling, fuel economy, tread wear, and load bearing. Over-inflation decreases traction, causes the tread to wear more quickly in the center, and wear suspension components faster. Underinflated tires have greater flex in the tires&#39; sidewalls. Excessive deflection causes wear closer to the sides, leads to more heat buildup that speeding wear, and greatly reduces fuel economy. Each tire is rated to carry a maximum amount of weight at a prescribed tire pressure. When there is insufficient air pressure in a tire to support a specific load, the extra heat generated in the tire can cause it to fail. Properly inflated pressure during vehicle operation can achieve optimal tire deflection for the best grip and will help to provide even wear and longer life of the expensive tires with substantially improved fuel economy. The concept of a tire inflation system has been implemented on commercial and military vehicles for many years. Many military vehicles are equipped with a central tire inflation system (CTIS) which incorporates both inflation and deflation features, allowing the pressure of the tire to be manually adjusted in response to the road conditions experienced by a vehicle. For example, on relatively soft terrain, the tires could be deflated somewhat to improve traction. In contrast, on harder surfaces, such as paved roads, the tires could be more highly pressurized. Nevertheless, currently available central tire inflation systems do not have real time tire pressure monitor capabilities nor able to intelligently and automatically manage tire pressure with respect to pressure variation, vehicle load and terrain conditions. For commercial vehicles, current tire inflation systems are designed to inflate tire pressure only. Their primary function is to ensure that tire pressure does not fall below a preset tire pressure. Without deflation capability, such systems often can only maintain a preset pressure when the tires were cold but unable to adjust the pressure when the tires got hot and might become overly inflated. Furthermore, one of the most important variables affecting the ideal amount of tire pressure is the load the vehicle tires need to carry but inflation-only system is unable to adjust the tire pressure in accordance to the vehicle load. 
     U.S. Pat. No. 6,145,559 issued to Rupert Henry Ingram on Nov. 14, 2000 discloses automated tire inflation by using a rotary union to connect a rotary axle and hub assembly. The assembly includes a rotary air connection assembly thread-ably mounted on the hubcap. 
     U.S. Pat. No. 6,585,019 B1 issued to Anthony L. Ingram on Jul. 1, 2003 discloses a rotary union assembly for use in an automatic tire inflation system for maintaining the desired pressure in the tires on a trailer or other vehicle having pressurized axles. The assembly communicates the valve stems on a pair of adjacent tires with the axle interior through the use of a flexible tube extending between a stationary first fitting thread-ably engaged in the axle spindle and a rotary housing secured against the outside end surface of the hubcap so as to be positioned exteriorly of wheel lubrication compartment and rotatable with the hubcap. 
     U.S. Patent US 2004/01732296 A1 issued to Jay D. White on Sep. 9, 2004 discloses a tire inflation system include an air supply in selective fluid communication with a tire via a pneumatic conduit. An inflation pressure of the tire is measured with a set-up procedure and the tire is inflated with an extended-pulse procedure. 
     U.S. Patent US 2006/0018766 A1 issued to Edmund A. Stanczak on Jan. 26, 2006 discloses a tire inflation system includes a hose that connects to a tire via a valve stem. A control valve is in fluid communication with the hose and senses when pressure falls below a predetermined minimum value. When this occurs, the control valve automatically opens to re-supply air to the tire until the predetermined minimum value is achieved. 
     U.S. Pat. No. 6,144,295 is issued to Brian Adams on Nov. 7, 2000 discloses a central tire inflation system for a work vehicle. The central tire inflation system controls the inflation pressure in the tires of a work vehicle. The central tire inflation system may be placed in an automatic or manual mode. In the automatic mode, the system make changes to the tire pressures according to the tire parameters, terrain conditions, and the operating loads placed on the tire. 
     U.S. Patent US 2007/0204946 A1 is issued to Martin A. Medley on Sep. 6, 2007 discloses a central tire inflation wheel assembly and valve. The valve includes a main body that is position-able in a sealed and recessed or embedded configuration within the aperture in the wheel rim in communication with the interior of the tire and with a pressurized air source that is used to inflate or deflate the tire. 
     Typically, these commercial tire inflation systems teach how to inflate air into tires through a rotary union with a one-way check valve that does not have tire deflation functionality. Such system mostly must operate continuously or periodically without knowing current tire pressure in individual tires. When inflation is not activated such systems are unable to detect any flat or leaky tire conditions. While military central tire inflation systems can perform tire pressure inflation and deflation functions, in order to avoid over burning the hub seal, these systems mostly can only check tire pressure during the periodic inflation and deflation activation time. Moreover, these teachings do not address nor provide intelligent tire management solutions to resolve many practical issues, as described below: 
     (i) Tire Inflation and Deflation with Real Time Monitoring 
     Properly pressurizing and monitoring tires in real time are utmost important for driving safety and for prolonging the life of tires. However prior commercial tire inflation systems only inflate tires and do not monitor individual tire pressure. It is technically challenging to monitor each tire pressure in real time for tire inflation systems. Currently there are no commercially available tire inflation systems incorporating embedded electronic unit into each wheel valve assembly for monitoring individual tire pressure, and inflate or deflate the tires only when tire pressure is deviate from a predetermined optimal level. Prior teachings generally do not present practical methods to combine real time tire pressure monitor with tire inflation and deflation for commercial vehicle applications. 
     (ii) Intelligent Tire Pressure Management. 
     There are many tire inflating systems available on the market and most of them are designed for trailer installation. Such systems mostly use compressed air from the vehicle air tank to inflate tires when tire pressure fell below a preset level. Air from the existing trailer air supply is routed to a control box and then fed into air tubes installed inside each hollowed trailer axle. The air tubes run through the axles to carry air through a rotary union assembly joined at the end of the wheel spindle in order to distribute air to each tire via the valve stem. Generally tire inflation systems do not support intelligent tire pressure management, must inflate the tires continuously or periodically for every trip, and often overly inflate the tires. 
     Existing tire inflation systems generally use an in-line flow sensor to monitor air flow and do not have direct pressure readings from the tires for controlling the inflation, therefore such systems typically do not know if preset pressure was maintained in the tires. Mostly such systems would deduce that there might be leaky or flat tires if overall pressure was still low after inflating a period of time. This indirect detection of air leak and flat tire is unreliable and usually belated. With frequent system operation, the excessive work load putting on the rotary hub seal unit and the air compressor will wear out the parts sooner and would lead to more expensive vehicle maintenance and even unsafe driving conditions. A tire inflation and deflation system integrated with real tire pressure monitor manages pressure intelligently based on real-time tire pressure data and vehicle load, adjusts tire pressure only when necessary and, as a result, works less and thereby reduces the vehicle maintenance costs. More importantly such an intelligent system improves vehicle safety for it would be able to promptly alert the driver low, leaky or flat tire conditions and enabling the driver to take immediate corrective actions. 
     SUMMARY OF THE INVENTION 
     A main object of the present invention is to provide an intelligent tire pressure management system with automatic and manual tire pressure inflation and deflation functionalities for commercial vehicles. Such a system is capable of keeping tires of an operating vehicle in a used-defined optimal pressure level in accordance to real-time tire pressure vehicle load and terrain conditions. A special wheel valve with embedded pressure monitoring electronic unit for each tire that works with a chassis mounting central control box provide the controlling features for intelligent tire pressure management. For dual tires, two wheel valves are incorporated into a hubcap mounting apparatus with a built-in rotary union to support inflating and deflating each dual tire pressure in real time. 
     Another object of the invention is integrating load sensors into the intelligent tire management system for monitoring vehicle load and, accordingly, inflating or deflating the tire pressure to the user defined or tire manufactory recommended ideal pressure. Current vehicle load information provided by the system enables the driver to readily determine if the load being transported is consistent with the vehicle limitations and whether vehicle weight regulations are met. Beneficially, the vehicle operator no longer needs to spend the time and expense at weigh stations. 
     Another object of the invention is a method for electronically detecting and counting each set of wheel&#39;s rotation and sending the count back to the central control unit for detecting wheel sliding caused by locked up wheels, and for calculating tire distance traveled and thereby facilitating regular tire maintenance. In addition, this method supports calculating tire speed for the system to control pressure settings in accordance to terrain condition. 
     Another object of the invention is a method for system communication and power supply to the wheel valve electronic unit by using a single wire connecting the central control unit and the hubcap mounting rotary wheel valve. System with battery-less electronic assembly and power line communication is more reliable and needs less maintenance. 
     Another object of the invention is to provide a central control unit with electronic circuitry, built-in keypad, LCD display, control valves and manifold for collecting tire pressure and temperature readings, measuring vehicle load, recording wheel rotation count, controlling tire inflation and deflation, and communicating tire management information through the power line. The central control unit is the brain of the intelligent tire management system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIGS. 1   a  &amp;  1   b  are drawings showing intelligent tire management system installed on respective 2-axle and 3-axle trailer axles. 
         FIG. 2   a  shows two isometric views of the rotary wheel valve assembly. 
         FIG. 2   b  is a drawing for the rotary mechanical face seal component of the rotary wheel valve assembly. 
         FIG. 2   c  is a cross-sectional drawing for the rotary mechanical face seal component of the rotary wheel valve assembly. 
         FIG. 3  is a cross-sectional drawing of the rotary wheel valve assembly mounted on the hubcap. 
         FIG. 4   a  is an angled cross-sectional side view of the rotary wheel valve assembly. 
         FIG. 4   b  is a cross-sectional top view drawing of the rotary wheel valve assembly. 
         FIG. 5  is a component drawing of the hubcap and rotary wheel valve assembly. 
         FIG. 6  is an isometric view of the rotary wheel valve assembly mounted on the hubcap. 
         FIG. 7  is an isometric view of the rotary wheel valve positioned above the hubcap with power supply wire and rotary seal shaft passing through respective hubcap opening. 
         FIG. 8  is an isometric view of the rotary wheel valve assembly mounted on the hubcap showing the inside of the hubcap. 
         FIG. 9  is an isometric view of the electronic manifold controller secured on a mounting plate. 
         FIG. 10  is an isometric view of the electronic manifold controller with cover lifted and showing the inside. 
         FIG. 11  is an isometric view of the manifold block of the electronic manifold controller with major components removed. 
         FIG. 12  is an angled cross-sectional view of the manifold block of the Electronic manifold controller. 
         FIG. 13  is the schematic of the rotary wheel valve electronic circuitry. 
         FIG. 14  is the schematic of the electronic manifold controller circuitry. 
         FIG. 15  is the schematic of the wheel valve sensor signal receiving section in the electronic manifold controller circuitry. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     An embodiment of the invention is described herein with references to the figures using reference designations as shown in the figures. 
       FIG. 1   a  is a drawing of the intelligent tire management system installing on a trailer chassis with two hollowed axles, where  101  is an electronic manifold controller for automatically controlling air inflation and deflation to all the tires. The electronic manifold controller gets pressurized air supply for inflation through air inlet  107  coming from the vehicle air compressor and releases air to the atmosphere for deflation through air outlet  108 . The electronic manifold controller also has multiple air outlets with each outlet communicating to a tire or a dual tire set through tubing  102  that laid along the vehicle chassis and then inserted into openings  103  on the hollowed axle and passed through the cavity inside the axle, eventually connecting to hubcap mounted rotary wheel valve unit  104 , which has air outlets connecting through hoses  105  to individual tire valve stems. The Rotary wheel valve unit  104  can open and close the air flow for tire inflation/deflation via its built-in wheel valves that are pneumatically controllable by the electronic manifold controller. Air inlet  106  gets pressurized air input from the vehicle suspension air springs for the electronic manifold controller to monitor pressure variation caused by changes in vehicle load, thereby enabling the system to adjust vehicle tire pressure for achieving the optimal tire deflection.  FIG. 1   b  shows a drawing with the intelligent tire management system being installed on a 3-axle trailer with hollowed axles. 
       FIG. 2   a  shows two different angled views of a wheel hub mounting rotary wheel valve unit  209  that includes two built-in wheel valves, rotary union, pressure and temperature sensors, magnetic sensor and the electronic control circuitry; each rotary wheel valve unit can support one or two tires. Underneath the removable covers  201  there are two built-in wheel values (not visible in  FIG. 2   a ) that control the opening and closing of the air path between the electronic manifold controller  101  and the tires; there are air passages inside rotary wheel valve  209  connecting the values to its respective air outlets  202  and  203  and then to the dual tires. Rotary union assembly  204  with a tubular shaft  210  is installed into a cavity in the rotatable rotary wheel valve base. The tubular shaft  210  with a central air passage is connected with the air tube from the electronic manifold controller  101  ( FIG. 1 ). Two print circuit boards (PCB)  207  with sensors exposed to the respective air passage connecting to the respective tire are responsible for monitoring tire pressure and temperature in real time. Sensor output connection wires  208  for PCB  207  are connected to PCB  206 , which contains the electronics that controls the sensors and communicates to electronic manifold controller  101 . The positive terminal of PCB  206  is electrically connected to the tubular shaft  210  through the rotary wheel valve base and the rotary union. A single wire connecting electronic manifold controller  101  to the tubular shaft  210  supplies power to PCB  206  and on the same wire supports electronic data and control signal communication between electronic manifold controller  101  and PCB  206 . Rotary wheel valve unit  209  is electrically insulated from the wheel hubcap top where it is mounted. To provide electrical grounding to PCB  206 , wire  205  is connected with the hubcap and from there to the vehicle chassis ground.  FIGS. 2   b  and  2   c  are detailed drawings of the rotary union, which is contained in housing  204  for installing in a cavity of the rotary wheel valve base with half of the rotary shaft exposed to outside. Shaft  210  is secured and support by bearings  211  in the housing in a way that the shaft can be stationary while the housing with the attached rotary wheel valve base can be rotatable. The shaft has in the housing end a seal face  212  that is facing an opposite seal face  213  for defining a rotary mechanical sealing interface, with spring  214  putting pressure on the back of seal face  213  for keeping a tight seal. The spring  214  chamber behind seal face  213  has air passage  215  leading to the valves. Each seal face has a central opening for air to pass through while one section is rotating and the other section is stationary. Now the electronic manifold controller can pneumatically control the opening and closing of the rotary wheel valves to direct air flow from the air source through the manifold, the air tubes, the rotary shaft central passage, the mechanical seal face central openings, the valves and finally reaching the tires, or the other way around. 
       FIG. 3  is a sectional drawing of a rotary wheel valve assembly mounting on hubcap  316  for illustrating air distribution within this apparatus. The two values underneath covers  201  showed in  FIG. 2   a  are indicated in  FIG. 3  by two areas surrounded by dash lines. For inflating tires, air from the electronic manifold controller  101  ( FIG. 1 ) with pressure higher than the tires passes through the tubing and enters inlet  317  at the tip of the rotary shaft  318 , flows through an air passage inside the rotary shaft, passes through rotary mechanical seal  303 , flows into cavity  302  and then flows into two separate air distribution passage  301  and  304  next to the respective wheel valve, from there air flows through small orifices  305  and  306  and into wheel valves  307  and  308 . The higher air pressure forces wheel values  307  and  308  to open and allows air flowing into air outlets  309  and  310  for filling the connecting tires.  FIG. 4  descriptions below discussed the opening of wheel valves with lower pressure source air from the electronic manifold controller to release the higher tire pressure. For deflating the tires, air flows in a reversed direction from the tires back to the electronic manifold controller and then to the atmosphere. Sensors  311  and  312  are installed in the air passage between the respective valve and the air outlet; each sensor is exposed to air from the respective tire for monitoring individual tire pressure and temperature. The electronic manifold controller powers the valve electronics via a single wire connecting to the metal rotary shaft  318  that is attached to the metal rotary wheel valve body. Thus the rotary wheel valve assembly is used as an electrical positive voltage power terminal for powering the electronics. The assembly includes electrical insulation sheets  313  and  314  placing between the rotary wheel valve and hubcap  316  for electrically insulating the rotary wheel valve with the metal hubcap. For electrical grounding, the PCB ground terminal wire will be connected with metal screw  315  to hubcap  316  that is mounted on the wheel. 
       FIG. 4   a  is a rotary wheel valve assembly cross-section side view showing the built-in wheel valve structure in detail. There are two valve bodies built into two cavities in the rotary wheel valve assembly unit, with the rotary union fitting into an additional middle cavity. This drawing shows a valve cross-section view from the narrow side and therefore the rotary union is not visible. A wheel valve has three chambers. The top chamber  410  is under removable cover  419  on one broad side of the rotary wheel valve housing and the bottom chamber  405  is under removable cover  415  on the opposite side. Top chamber  410  has a poppet  412  that sits on seat  416  and separates the top chamber from the middle chamber  407 . The middle chamber  407  contains a movable piston  408  with a large base  417  disposed against a flexible diaphragm  406  that separates the bottom chamber  405  from the middle chamber  407 ; the other end of the piston forms into a slender tip that fits into a cavity on the underside of poppet  412 . The lower portion of the middle chamber  407  shapes into a cylinder tube  423  ( FIG. 4   b ), which has a tight clearance between the cylinder wall and the piston  408  for restricting middle chamber air getting through to the piston base area. The bottom chamber  405  connects to the source air distribution passage  401  through air passage  402 , whereas the middle chamber  407  also connects the source air distribution passage  401  but through orifice  404 . Top chamber  409  connects to air passage  411  that leads to the tire port outlet. Spring  409  inside top chamber  409  is disposed under the cover  419  and pressed against poppet  412 . Pressure sensor  413  is for monitoring air passage  411  to obtain real time pressure and temperature of the connecting tire. Sealing O-Ring  403  is for preventing chamber air and passage way air leaked through the gap between removable valve cap  415  and the apparatus body. When pressurized air flows into the bottom chamber  405 , the pressure exerting through the flexible diaphragm  406  on piston base  417  will force the piston  408  to move upward against poppet  412 . When the wheel valve is not pressurized, spring  409  will exert pressure on poppet  412 , force the poppet to sit on the seat  416  and thereby close the valve. Otherwise, if the combined tire pressure and spring  409  pressure are smaller than the combined middle chamber  407  air pressure and the upward force exerting on poppet  412  that is produced by the bottom chamber  405  air pressure applying through piston  408 , poppet  412  will be forced to move upward and unseat from the seat  416 , thereby open the valve and allow air communication between the tire and the air source. 
       FIG. 4   b  shows that above piston base  417  there is a sealing o-ring  418 , next to the o-ring there is a small cavity  420  with a breathing hole  421  leading to atmosphere. Dust cover  422  is for covering up the breathing hole. When piston  408  moves toward poppet  412 , o-ring  418  will seal off the cylinder base and prevent air leakage from the middle chamber to cavity  420 . However, even though there is a tight clearance between piston  408  and cylinder  423  and the piston base o-ring  418  would provide a good air seal, air in the middle chamber  407  could still seep through and reach cavity  420  and causing pressure build-up in the cavity that would counteract the bottom chamber  405  pressure through diaphragm  406 , thereby affecting the effectiveness of the piston upward movement. Therefore it is important to release any build-up air in cavity  420  to the atmosphere. 
     As described above for the wheel valve, even if the source air pressure is lower than the target tire pressure in top chamber  409 , the valve can be opened by the combined source air pressure in chamber  407  and the additional push-up force exerting on poppet  412  that is produced by the bottom chamber  405  air pressure applying through piston  408 . This wheel valve design can support pneumatically controllable opening of the valve and releasing of tire air with a source air pressure at ⅔ or more of the tire pressure. For tire deflation applications, the electronic manifold controller can monitor the tire pressure in real time and maintain proper source air pressure accordingly for keeping the wheel valves open to release tire air. During deflation, the electronic manifold controller will open the solenoid deflation valve and release air to atmosphere through the deflation orifice. In this way high tire pressure can be gradually reduced to a desirable level. 
     The wheel valve can be quickly closed when source air is rapidly withdrawn, causing source air pressure to be less than ⅔ of tire pressure. When source air is withdrawn, orifice  404  limits air in the middle chamber  407  from flowing out too quickly, whereas the air in bottom chamber  405  will escape faster and loss the pressure to push up piston  408 , leading to the lowering of poppet  412  to sit on seat  416  and thereby close the valve. 
       FIG. 5  is a drawing showing the hubcap and rotary wheel valve assembly components. Rotary wheel valve body  502  has two removable top valve caps  505  and two bottom valve caps  512 . The two tire ports have hose fittings  501  and  513  with locking set screws and air sealing O-Rings  503  and  511 . Rotary union air inlet shaft  504  and wheel valve body  502  are to be electrically insulated from hubcap  521  using two insulation sheets  514  and  515 . Metal plate  516  is affixed on the rotary wheel valve but also keeps electrically insulated by insulation sheets  514  and  515 . Metal plate  516  is used for installing the wheel valve on hubcap  521  with screws. Magnet holder plate  517  with embedded magnet  506  is mounted on the stationary shaft for magnet sensor in the rotatable wheel valve electronics to detect the presence of magnetic field when the magnet passes by during wheel rotation, thus enabling the counting of wheel rotation for calculating tire usage. Another function of wheel rotation detection supports detecting locked wheels during extremely cold weather conditions. The rotary union shaft extension  507  slip into insulation holder  508  which insert into a coupling holder  509  with O-Ring  510 . Metal contact ring  519 , is connecting with a wire for providing positive electrical terminal connection to the metal rotary wheel valve body. The  518  is a security screw for  519  and then the  520  provides air tube fitting. Hubcap  521  has mounting holes on top for rotary wheel valve assembly installation. 
       FIG. 6  is a drawing showing rotary wheel valve assembly  603  mounted on hubcap  611  with accessories attached. Bolts  602  are for mounting the hubcap to the wheel axle. Two extension hoses  601  and  610  connect the rotary wheel valve tire ports to the respective dual tires valve stem. Air tube  608  from the electronic manifold controller is connected to rotary union shaft  604  and secured by fitting  607 . Positive electrical wire  612  from electronic manifold controller is connected to positive electrical terminal contact ring  609  for powering the rotary wheel valve electronic unit and carrying communication data. An insulation holder cup is made up of two halves  606  and  607 ; the cup has a center hole for rotary union shaft  604  to pass through while keeping shaft  604  electrically insulated from the surrounding. The insulation holder cup is for plugging into the axle spindle bore and holding in place the rotary union shaft  604  and the connecting air tube  608 . 
       FIG. 7  is a drawing showing rotary wheel valve assembly  702  on top of hubcap  705  with rotary union shaft  709  inserting through an opening on the hubcap. Two insulation sheets  703  and  706  electrically insulate the rotary wheel valve from the hubcap, which is electrically in contact with the vehicle body. The rotary wheel valve electrical ground connection wire  701  runs through a small hole on the hubcap and then connects with hubcap bottom ground screw  801  ( FIG. 8 ) for providing ground terminal connection to the rotary wheel valve electronic unit. Two small glass windows  707  on top of the hubcap are for viewing the axle lubrication oil level and the  708  is for refilling the lubricant. 
       FIG. 8  is a hubcap and rotary wheel valve assembly inside view drawing. The  801  is a hubcap ground screw that is covered and protected by the bottom electrical insulation sheet. The  802  is a magnet holder plate to be secured on rotary union shaft  803  and is embedded with a magnet. When the vehicle moves, the electronic circuitry in the rotating rotary wheel valve can detect the presence of the magnetic field whenever passing by the magnet, and therefore is able to count the number of wheel rotation for calculating the distance of the vehicle traveled. 
       FIG. 9  is a drawing showing the electronic manifold controller secured on a mounting plate. Mounting plate  901  with mounting holes  902  is for mounting the electronic manifold controller  903  on the vehicle chassis. The electronic manifold controller has  4  legs  911  with screw holes for attaching the mounting plate. The electronic manifold controller has a weatherproof cover  904 . Noise reduction muffler  905  is for suppressing the loud noise produced by the pressurized air rapidly releasing from quick exhaust valve  1008  ( FIG. 10 ) when closing the rotary wheel valves. The  908  is a LCD display showing data, warnings and control information. Keypad  909  is for user entering commands and programming the electronic manifold controller. Air source inlet  907  takes in pressurized air input from the vehicle air compressor for inflation and deflation operations. The other air inlet  906  takes in the pressurized air input from the vehicle air springs for calculating vehicle load. Air ports  910  connect to the respective rotary wheel valve via air tubes going through the vehicle&#39;s hollow axles. Each air tube is bundled with a wire for connecting the electronic manifold controller with the rotary wheel valve; the wire is for providing power to wheel valve electronics and for data communication. 
       FIG. 10  is a drawing showing the inside of the electronic manifold controller. The electronic manifold controller cover  1001  can be plastic or metal and is weatherproof. Connector  1006  is for connecting to an external power source and for outputting alarm signals. Connector  1007  is for connecting to each rotary wheel value with a single wire for providing power and for data communication. The manifold has an air chamber inside that is connecting to deflation solenoid valve  1002 , inflation solenoid valve  1003 , quick exhaust solenoid valve  1008 , pressure transducer  1010 , and air ports  1014 . Pressure transducer  1010  monitors the air pressure in the manifold air chamber. The normally close inflation valve  1003  can be opened and let in through air inlet  1013  the pressurized air from the vehicle compressor for opening the wheel valve and inflating tire pressure. The normally closed deflation valve  1002  can be opened to slowly release tire air through a deflation orifice to the atmosphere; the manifold controller would manage the pressure for keeping the rotary wheel valves to stay open during the deflation period. Priority pressure sensor  1004  connects to air inlet  1013  and monitors the vehicle compressor pressure level to ensure that the manifold controller would not perform tire inflation when the compressor pressure is at or below a safe level to support normal vehicle braking operation. Load sensor  1005  connects to air springs inlet  1015  and monitors vehicle suspension air springs pressure for the manifold controller to calculate current vehicle load, thus enabling the system to determine if vehicle tire pressure needs to be adjusted with respect to full vehicle load, half load and empty load for keeping tires in optimal pressure condition. The  1009  is one of the four legs with screw ports for securing the manifold on the mounting plate. 
     The manifold air chamber and the connecting air tubes and the wheel valves are normally not pressurized. Whenever necessary, the system will conduct a sequence of steps to perform tire pressure adjustment. In a pressure adjustment procedure, the system will first monitor air source through priority pressure sensor  1005  to ensure there is sufficient air pressure to support the system operation. Next the system will close the normally open quick exhaust valve and open the inflation valve for building up manifold air chamber pressure to a level that will cause the opening of all rotary wheel valves connecting to the tires. If there are no flat or leaky tires, tire air would flow through the opened wheel valves, balance through the manifold air chamber and thereby achieves tire pressure equalization. The system would use pressure transducer  1010  to measure manifold chamber air pressure for determining current tire pressure. If the manifold chamber pressure is lower than target set point pressure then the system would open the inflation solenoid valve and fill up the tires to the desired pressure level with source air. If the tire pressure is higher than the desirable level then the deflation solenoid valve will be opened for releasing air. During inflation or deflation, whenever manifold chamber pressure reaches the target set point, the system will open the quick exhaust solenoid valve to rapidly release the pressurized air in the manifold chamber, the air tubes and the valves that will cause the immediate closing of all rotary wheel valves. 
     In a normal vehicle operation, when the vehicle starts up the system will carry out the pressure adjustment procedure once to establish proper operating tire pressure. During the vehicle travelling trip, the system will continuously collect tire pressure and temperature information in real time from the wheel valves sensors but does not adjust the tire pressure until pressure variation exceeded a predetermine tolerance. If a tire leak develops and causes pressure slowly to drop then a warning will be issued, meanwhile the system will try to maintain the tire pressure through inflation to compensate for the gradual air loss. If a tire blowout occurred and caused air loss rapidly, however, the system will not attempt to maintain the tire pressure but issue a warning to alert the driver. In a normal vehicle operation the tires will get hot after a prolong drive, and the tire pressure could be substantially higher than cold tire pressure, in this case the system will deflate tire pressure to the desired level for protecting the tires. When tires cool down and the pressure drops down, the system will be adjust the tire pressure back to the normal level. With the load sensor  1015  measuring pressure data from the vehicle air springs, this intelligent system can determine the vehicle load (e.g., full/half/empty) for automatically adjusting tire pressure in accordance to the tire manufacturer&#39;s recommended tire pressure with respect to load. The system also supports manual selectable adjustment of tire pressure based on vehicle load such as full/half/empty load and road conditions such as snow, mud, sand, highway, or cross country driving. The system also has a fail-safe operating procedure when the tire data becoming unavailable (e.g., wheel valve electronics went down). In this situation the system will automatically perform tire pressure adjustment every half hour or so. 
       FIG. 11  is a drawing of the electronic manifold controller base without the components. The  1101  is a metal manifold base. The pressure transducer mounting hole  1109  connects to the manifold air chamber for the mounted pressure transducer to monitor the manifold air chamber pressure. The quick exhaust valve cavity  1103  is connected through an inside passage to air outlet  1107  that opens to the atmosphere; air outlet  1107  would be fitted with a noise reduction muffler. The quick exhaust valve is also connected with the manifold air chamber through cavity  1102 . The  1104  is the deflation valve cavity and  1105  is the inflation valve cavity. The  1108  is the priority pressure sensor mounting hole and the  1106  is the load sensor mounting hole. Manifold air ports  1110  communicate to all rotary wheel valves through the connecting air tubes. 
       FIG. 12  is an electronic manifold controller base section inside drawing. Deflation solenoid valve cavity  1202  communicates with manifold chamber  1211  through an air passage. Deflation valve also communicates with cavity  1201  that, through air passage  1207 , connects to cavity  1208  that opens to the atmosphere through an orifice. Cavity  1201  has a deflation orifice restricting air releasing speed for maintaining a proper wheel opening pressure during deflation. When deflation valve opens, manifold chamber air will flow out from the manifold chamber through the previous described air paths to the atmosphere. To increase manifold chamber air pressure, solenoid inflation valve is activated to open up the air path for air flowing from inlet  1203  into inflation valve cavity  1215  and then through cavity  1214  flowing into the manifold air chamber  1211 . The priority pressure sensor can monitor air source pressure from sensor mounting hole  1216 . The load sensor can monitor vehicle load pressure from sensor mounting hole  1217  which is connects to the vehicle suspension air springs pressure inlet  1204 . To close all rotary wheel valves, quick exhaust solenoid valve is opened to quickly release air in manifold chamber  1211  through the large exhaust hole  1210  leading to atmosphere hole  1208 . The hole  1212  is mounted with the pressure transducer for monitoring the manifold chamber air pressure. The manifold chamber air ports  1218  connect to all rotary wheel valves by air tubes. Screw hole  1205  is one of the ten holes for securing the weatherproof cover on the manifold controller base with screws. Each of the four legs  1209  on the manifold base has threaded hole for securing on the mounting plate with a screw. 
       FIG. 13  shows a schematic of the rotary wheel valve electronic circuitry. One electronic unit works with two wheel valves and consists of a data processing PCB  1301  and two sensor PCBs  1303  and  1304 . Each sensor PCB contains a piezoresistive pressure sensor S, resistors RS 1 , RS 2 , RS 3 , RS 4  and a micro-power amplifier AMP. Sensor S comprises four strain resistant sensitive resistors diffused in silicon. These resistors are connected in a Wheatstone bridge configuration, whereby two resistors increase resistance with positive pressure while the other two resistors decrease in resistance. When pressure is applied to the sensor, the resistors in the arms of the bridge of the sensor changed resistance by an amount directly proportional to the pressure applied. When a voltage is applied to the bridge, there will be a resulting differential output voltage based on arms resistance that can be used to calculate the sensed tire pressure. The micro-power amplifiers AMP with resistors RS 1 -RS 4  condition the sensed tire pressure voltage to a high level for A/D conversion. These two sensor PCBs are secured in locations  207  ( FIG. 2   a ) of the two rotary wheel valves are fully sealed. Each sensor PCB has four wire terminals connecting to the data processing PCB  1301 . 
     The data processing PCB  1301  is installed in location  206  of the rotary wheel valve unit  209  ( FIG. 2 ). The positive voltage power from electronic manifold controller  101  ( FIG. 1 ) to rotary wheel valve unit, as described in the  FIG. 2   a  description, is connected to VCC/DATA input terminal  1302  of data processing PCB  1301  and further connected to protection diode D 1  and coupling capacitor C 4 . As described in the  FIG. 2   a  description, the power input from electronic manifold controller  101  cannot be connected directly to the PCBs of the rotatable rotary wheel valve unit  209 . Instead the input wire is connected to rotary union shaft  210  so that input power must pass through rotary union bearings and lubricants in the rotary wheel valve assembly before reaching the PCBs. As a result the input power voltage would be unstable due to electrical resistant variations in the power travelling path. To establish a stable power supply, PCB  1301  includes low-drop power regulator U 1  for converting input voltage to +3V and together with capacitor C 1  will stabilize the voltage. A high performance CMOS eight-bit microprocessor U 2  with filter capacitors C 2  and C 3  processes data, controls I/O and manages power. The data processing PCB  1301  further consists one micro-power magnet sensor U 3  plus a 125 KHz serial resonance loop C 5  and L 1  connecting to CPU modulated data output U 2 &#39;s pin 3 . The tire pressure voltage signals from two sensor PCBs are inputs to the PCB  1301 &#39;s on-chip A/D converter of microprocessor U 2  for producing the tire pressure measurements in digital form. To reduce component cost, this PCB  1301  design utilizes one microprocessor to process inputs from both pressure sensors and then combines the dual tire pressure data to form a single message for 125 KHz low frequency signal transmission through the power line back to the electronic manifold controller. 
     For reducing the PCB circuit size, an internal 4 MHz RC oscillator is used to clock the microprocessor U 2 . Under program control, microprocessor U 2  outputs an encoded digital message data string for amplitude shift keying modulation with the 125 KHz carrier signal coming from the internal pulse-width modulator (PWM) circuit. The U 2  outputs include the dual tire temperature readings that are calculated from sensor S data sent to respective U 2  pin  6  and pin  10  through serial resisters R 2  and R 3  connection. 
       FIG. 14  shows an electronic manifold controller schematic diagram for the electronic design of the power module, display/keypad module, ccommunication module, central data processing module, temperature sensor module, pressure sensor module, solenoid driver module and rotary wheel valve electronic unit power/data processing module. The power module includes power protection circuitry with one +12V regulator U 2 , one +5V precision regulator U 1  and one +5V high current regulator U 7 . The display/keypad module includes one LCD module LCD 1  with built-in LCD driver for information display and a keypad switch connector SW 1  to handle keyed-in data input by user. The communication module includes one CAN bus driver U 6  and one power line communication transceiver U 10  to handle data communication between the electronic manifold controller and user electronic devices installed on the vehicle. The central data processing module has a high performance central processor unit U 8  to process all data, handle input and out, and intelligently manage tire pressure with respect to vehicle load and terrain conditions. The temperature module is a precision temperature sensor U 9  that provides environment temperature for system sensor automatic calibration. The pressure sensor module includes one priority pressure sensor U 3 , one air springs load sensor U 4  and manifold transducer U 5 . The solenoid driver module includes pre-driver Q 2 , Q 3 , Q 4  and high power driver Q 5 , Q 6 , Q 7  to active deflation solenoid valve, inflation solenoid valve and quick exhaust solenoid valve. This electronic manifold controller schematic diagram shows support for up to 6 trailer tires. The circuit design can be easily modified to support more or less tires. The power supply and data processing module U 11  for rotary wheel valve electronic unit  209  is descripted next in  FIG. 15  discussions. 
       FIG. 15  shows the U 11  circuitry that supports providing stable power to the rotary wheel valves electronic unit  209  from electronic manifold controller  101  and performing data demodulation using the same power wire. Power from the electronic manifold controller must pass through the rotary union bearings to reach the rotary wheel valves electronics, and then return to the ground (i.e., vehicle chassis) through the hubcap and the wheel axle bearings. It is technically very challenging to maintain stable power supply through bearing contacts and at the same time support reliable data and control signal communication between the two devices. Since a vehicle axle bearing contact resistance might change randomly from a few Ω&#39;s to over 10KΩ and would cause the current flow to fluctuate if the voltage remains constant, it is necessary to be able to dynamically adjust the voltage level with respect to the resistance changes for maintaining a stable power supply. The  FIG. 15  schematic diagram shows circuit design to support  6  power lines, where U 1  to U 6  are six current limiters providing stable power to rotary wheel valves electronics through the respective AX 1  to AX 6  connection. The R 1  to R 6  are current sensing resistors and the C 1  to C 6  are filter capacitors for suppressing interfering electronic noise. To transmit data over the noisy DC power line, sensor data is modulated by a low frequency 125 KHz carrier. The six parallel resonance loops L 1 -L 6  and C 7 -C 12  show high impedance for carrier frequency and show low resistance for DC to power AX 1  to AX 6 . The coupling capacitors C 13 -C 18  remove the DC elements and only pass AC signals into multiple switch U 7 . By selecting A 0 -A 2  level with the CPU, U 7  can be switched to one of the AX 1 -AX 6  inputs, and the output signals from U 7  is connected to the following carrier amplifier that is composed of one NPN transistor Q 2 , base bias resistors R 10 -R 11  and carrier resonance loop L 7 -C 20 -R 8 . The NPN transistor Q 2  outputs the carrier signal through C 21  and R 9  to data detector Q 1  with R 7 , and C 22  for data demodulation. 
     The above system and methods describe a preferred embodiment using exemplar devices and methods that are subject to further enhancements, improvement and modifications. However, those enhancements, improvements modifications may nonetheless fall within the spirit and scope of the appended claims. 
     Additional Preferred Embodiments and Scope 
     The above preferred embodiment illustrated a typical embodiment of the present invention. Although the description above contains much specificity, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. There are various possibilities with regard to additional embodiments. Thus the scope of the invention should be determined by the following claims and their legal equivalents, rather than by the examples given.