Abstract:
Methods of monitoring tire pressure and responding to a tire pressure error. A tire pressure monitoring apparatus provides signals to a vehicle control representing pressures in respective ones of the tires. The vehicle control first detects a tire pressure error in one of the tires, and then presents to a user a first signal representing the tire pressure error in the one of the tires. Then, a user input representing a prospective tire filling activity is detected. Thereafter, a second signal is presented to the user in response to a pressure in the one of the tires being substantially equal to a desired tire pressure.

Description:
FIELD OF THE INVENTION 
     The invention relates generally to a tire monitoring and warning system and more particularly, to a tire pressure monitoring cycle in response to tire cavity pressures. 
     BACKGROUND OF THE INVENTION 
     It is well documented that maintaining a correct tire pressure improves handling, increases gas mileage, and extends the useful life of vehicle tires. Moreover, maintaining a correct tire pressure is an important consideration to the safe operation of a vehicle. Despite its irrefutable importance, tire pressure may not be monitored and maintained frequently enough by many in the driving public. Even well maintained tires may undergo a loss of pressure during the operation of a vehicle after sustaining damage, creating a potentially hazardous situation to the operator. In addition, with the advent of “extended mobility tires” (EMT) and their increasingly widespread commercial presence, it may be difficult for a vehicle operator to detect a low pressure or leak condition and take appropriate action. As a result, extended use of a tire in a low pressure condition beyond the manufacturer&#39;s recommended limit may occur. 
     Tire pressure monitoring systems have been developed and are in limited use. Such systems typically comprise a sensor located in the tire to perform real-time interior air pressure and temperature monitoring. The information is wirelessly transmitted to the driver via radio frequencies (RF) and displayed in the driver compartment of the vehicle. The remote sensing module consists of a tire condition monitor, for example, a pressure sensor and/or a temperature sensor, a signal processor, and an RF transmitter. The system may be powered by a battery or the sensing module may be “passive”; that is, power may be supplied to the sensing module by way of magnetic coupling with a remote transmitter that is connected to an electronic control unit (“ECU”). The ECU can either be dedicated to tire pressure monitoring or share other functions in the car. For instance, the ECU could be a dashboard controller or other onboard computer. Examples of such tire monitoring systems are more fully described in U.S. Pat. Nos. 6,868,358 and 6,591,671 owned by the assignee of this application, which patents are hereby incorporated in their entireties by reference herein. 
     The purpose of a tire monitoring system is to provide the driver with a warning should a pressure anomaly occur in one or more tires. Typically, tire pressure and temperature are reported parameters. To be useful, the information must be quickly communicated and be reliable. Further, simply displaying the tire pressure information does not help a user remedy the situation. Therefore, there is a need for a tire monitoring system that not only displays tire pressure anomalies but also assists the user in satisfactorily resolving those anomalies. 
     SUMMARY OF THE INVENTION 
     The present invention provides a simple, integrated tire pressure monitoring system that not only warns of incorrect tire pressures but also facilitates a user in providing correct tire pressures. 
     According to the principles of the present invention and in accordance with the described embodiments, the invention provides a method of monitoring pressures in respective tires of a vehicle. The vehicle has tire pressure monitoring apparatus providing signals to a vehicle control representing pressures in respective ones of the tires. The vehicle control has user I/O and the method first detects a tire pressure error in one of the tires, and then presents to a user a first sensory perceptible signal representing the tire pressure error in the one of the tires. Then, a user input representing a prospective tire filling activity is detected; and thereafter, a second sensory perceptible signal is presented to the user in response to a pressure in the one of the tires being substantially equal to a desired tire pressure. Thus, the method provides the user assistance in determining when a tire is properly filled after a tire pressure error has been displayed. 
     In one aspect of this invention, the first sensory perceptible signal is a visual display; the user input is an input button on a visual display; and the second sensory perceptible signal is either a visual display or an audible signal. 
     In another embodiment, the method detects a change in tire pressure in a first tire and determines if the first tire is substantially the same as the one of the tires. Then a third sensory perceptible signal is presented to the user in response to the first tire being different from the one of the tires. In one aspect of this invention, the third sensory perceptible signal is either a visual display or an audible signal. 
     These and other objects and advantages of the present invention will become more readily apparent during the following detailed description taken in conjunction with the drawings herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic block diagram of one exemplary embodiment of a tire condition monitoring system in accordance with the principles of the present invention. 
         FIG. 2  is a schematic illustration of one example of a display for presenting tire condition data to a user with the tire condition monitoring system of  FIG. 1 . 
         FIG. 3  is a schematic flowchart illustrating a process of using the tire condition monitoring system of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , a tire condition monitoring and control system  20  is installed on a vehicle  22 , shown in phantom, for example, a passenger vehicle having four pneumatic tires  24   a ,  24   b ,  24   c  and  24   d  installed on four respective wheels (not shown). The vehicle  22  is equipped with a multiplexed, bidirectional serial data bus  26 , for example, an RS-485, a LAN or comparable data bus, which may be implemented with a twisted pair of insulated wires. The serial data bus  26  is connected to a serial data bus interface  30  within an ECU  28 , for example, an on-board vehicle computer, an in-dash controller or comparable computer or controller. The ECU has a display unit  32 , for example, an in-dash touch screen, an LCD screen or comparable display, that is connected either directly to the ECU  28  as shown, or is indirectly connected to the ECU  28  via the serial data bus  26 . It is within the scope of the invention that if no data bus is provided on the vehicle, one can be added thereto. For example, in the absence of an existing vehicle data bus, a dedicated data bus may be provided in accordance with known serial communications standards acceptable for this application. 
     The four tires  24   a - 24   d  are equipped with respective known electronic modules (“tags”)  34   a - 34   d , respectively, and known respective tire condition sensors  33   a - 33   d  that are capable of monitoring one or more conditions such as air pressure and/or air temperature within a respective tire. Each tag is operative to transmit radio frequency (RF) signals indicative of, or modulated as a function of, one or more monitored conditions within a respective vehicle tire. In one exemplary embodiment, the tags  34   a - 34   d  are transponders such as those used with radio frequency identification tags but may alternatively simply comprise one or more condition sensors and a radio frequency transmitter. 
     The system  20  also has four known monitors or interrogation units  36   a - 36   d  associated with respective tires  24   a - 24   d  and preferably located in proximity therewith, for example, mounted within respective wheel wells of the vehicle  22  in a known manner. The monitors  36   a - 36   d  are connected to a source of power (not shown) and are also connected to the serial data bus  26  for individually communicating with the ECU  28 . The monitors  36   a - 36   d  have respective antenna  38   a - 38   d  and respective transmitter/receivers (not shown) for transmitting signals to, and receiving signals from, respective tags  34   a - 34   d . The monitors  36   a - 36   d  may be implemented using a data transceiver, for example, a DS36277 Dominant Mode Multipoint Transceiver commercially available from National Semiconductor of Santa Clara, Calif. 
     A monitor&#39;s transmissions to a respective tag may comprise a carrier signal for energizing a passive tag, and may comprise signals to “wake up” an active tag which is in a low-power sleep mode. It is within the scope of the invention that all components of a monitor  36   a - 36   d  including a respective antenna  38   a - 38   d  can be encapsulated in a single package. Alternatively, the antenna can be disposed outside of such a package. 
     Monitored tire condition data carried by the RF signals from tags  34   a - 34   d  may be decoded, for example, demodulated, provided to the ECU  28  and presented to a user via the touch screen display  32 . In a known manner, visual warnings and alarms may be presented to a user via the touch screen  32 . In other known embodiments, audible warnings and alarms may be presented to a user by the ECU  28  activating an audio signal generator  40 . The audible signals may be in the form of synthesized voice messages and/or beeps, chimes, buzzes or other sounds of differing durations and/or frequencies or other audio signals. The exact form of the sensory perceptible signals, for example, the audible and visual warnings and alarms, is often determined by a vehicle manufacturer. Additionally, the information regarding dynamic conditions of the tires can be utilized in controlling the vehicle, such as by providing relevant inputs to a “smart” suspension system. 
       FIG. 2  illustrates one of many alternative tire information display configurations that may be implemented using the in-dash touch screen  32 . An array of four vertical bars  44 ,  46 ,  48 , and  50  may be used to represent the respective four tires  24   a - 24   d  of the vehicle  22  shown in  FIG. 1 ; and icons  52 ,  54 ,  56  are employed to indicate respective good, cautionary and unacceptable tire pressure ranges. Displays of the icons  52 - 56  representing tire pressures are demonstrated in the vertical bars  44 - 50 . The choice of icons and associated displays may vary depending on the vehicle manufacturer. An outside temperature may also be displayed as shown at  58 . 
     A process for utilizing the tire pressure monitoring system  20  of  FIG. 1  is illustrated in  FIG. 3  as a tire pressure cycle program or sub-routine  302  that is executed using the ECU  28  or comparable computer. The ECU  28  first, at  304 , determines, in a known manner, whether there is any tire pressure error detected by any of the tire condition monitors  33   a - 33   d . The tire pressure error is then, at  306 , displayed using the touch screen  32  in a display configuration comparable to that illustrated in  FIG. 2 . If any of the displays  44 - 50  indicate a cautionary pressure or an unacceptable pressure as indicated in displays  46  and  48 , the ECU  28  then displays a fill push button  60  on the touch screen  32 . In this exemplary embodiment, the fill push button  60  is activated by a user prior to changing the air pressure in any of the tires  24   a - 24   d . The activation of the fill request push button is detected at  308  by the ECU  28 . The fill push button  60  may only become visible when the ECU  28  detects that the vehicle  22  is stopped and in a parked position or, additionally, when a fueling activity is detected while the vehicle  22  is in the parked position. In the latter regard, the fill push button  60  may only become visible when the fuel filler door is detected by the ECU  28  to be open. 
     Thereafter, at  310 , the ECU  28  then monitors the air pressure in each of the tires  24   a - 24   d  to detect whether air pressure in any of the tires changes. If a tire pressure change is detected, then, at  312 , ECU  28  determines whether the tire in which the pressure is changing is one of the tires requiring an adjustment to its air pressure, for example, tires  24   b  or  24   c  as indicated by the respective displays  46  and  48 . If the air pressure in any of the other tires is changing, for example, tires  24   a  or  24   d , in which the pressure is acceptable as shown by displays  44  and  50 , the ECU  28  then, at  314 , generates a wrong tire alarm signal. Such a signal may be an audible alarm provided by the audio signal generator  40  and/or a visual alarm on the display  32 , which is created, for example, by changing the color of the displays  44 ,  50  or causing the displays  44 ,  50  to blink. 
     If, at  312 , the ECU  28  determines that the tire pressure being changed corresponds to a tire having a tire pressure error, for example, tires  24   b  or  24   c , the ECU  28  then, at  316 , continues to monitor the change in tire pressure until it reaches an acceptable level. At that point, the ECU  28  outputs, at  318 , a correct pressure signal that is represented on the display  32  by the acceptable icon  52 . In addition upon reaching an acceptable tire pressure level, the displays  46 ,  48  may switch to a green color, either as a solid color or blinking. In addition, an audible signal representing an acceptable tire pressure may be created by the audio signal generator  40 . The ECU  28  then, at  320 , determines whether all of the tires have an acceptable pressure. If a tire pressure error still exists, the process described with respect to steps  304 - 320  is repeated. Upon ECU  28  determining that all of the tires  24   a - 24   d  are at an acceptable pressure, then, at  322 , the ECU  28  generates an appropriate visual display and/or audio signal. 
     While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of Applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broadest aspects is not limited to the specific details shown and described. Consequently, departures may be made from the details described herein without departing from the spirit and scope of the claims which follow.