Abstract:
Methods and apparatus are provided for detecting when a spare wheel (SP) is used to replace a previously rolling wheel on a vehicle, where each wheel can transmit wheel ID and motion status signals. The apparatus comprises a receiver, a memory for storing information relating wheel ID and location, a processor coupled to the receiver and memory for analyzing the wheel signals to determine if the SP is rolling, and a timer coupled to the processor that measures how long the SP has been rolling. When the SP has been rolling for predetermined time T, the processor looks at the motion status signals from remaining wheels to determine which is stopped, and then modifies the information stored in the memory to associate the SP ID with the wheel location formerly occupied by the now stopped wheel and associate the stopped-wheel ID with the storage location for the spare.

Description:
TECHNICAL FIELD  
       [0001]     The present invention generally relates to systems and methods for monitoring wheel and tire usage on vehicles, and more particularly, automatically determining whether a vehicle spare tire has been put into active use on the vehicle.  
       BACKGROUND  
       [0002]     It is known to provide RF sending units on vehicle wheels that provide information to a central radio receiver and processor on the vehicle about the status of the wheel, e.g., the wheel identity number (ID), the wheel location, whether it is rolling or stationary, wheel temperature, tire pressure, and so forth. Such systems are described for example in U.S. Pat. No. 5,109,213 to Williams; U.S. Pat. No. 6,441,728 B1 to Dixit et al, U.S. Pat. No. 6,4876,773 B1 to Baille et al, U.S. Pat. No. 6,518,876 B1 to Marguet et al and U.S. Pat. No. 6,580,365 B2 to Starkey.  
         [0003]      FIG. 1  is a simplified schematic diagram of prior art system  9  comprising five vehicles wheels  10 A- 10 E interacting with on-board data receiver  14 . Each vehicle wheel  10 A- 10 E, has transmitter or sender  11 A- 11 E coupled to instrumentation package  13 A- 13 E and to antenna  12 A- 12 E. Instrumentation package  13 A- 13 E provides wheel ID, location and status information that is sent via RF signal  18 A- 18 E from sender  11 A- 11 E via antenna  12 A- 12 E to on-board receiver  14  via antenna  15 . Depending upon the particular approach used for correlating wheel ID and wheel location, signals  18 A- 18 E may be bi-directional and/or encompass location transmitters or transceivers in the wheel wells, but this is not important to the present invention. Such systems are well known in the art and described, for example, in the above-referenced patents.  
         [0004]     In many cases, these systems have two modes of operation: (1) a learning mode in which the wheel mounted unit interacts with a vehicle mounted location unit so that information on the tire ID and location on the vehicle can be related and learned by the vehicle electronics system so that it knows which wheel is where on the vehicle, and (2) an operating mode where the individual wheel sending unit transmits or sends its ID, location and status (e.g., rolling, temperature, pressure, etc.). In many arrangements the learning mode is only infrequently invoked, for example, when the wheels are mounted on the vehicle at the factory or when the wheels are rotated at a service location and the service technician accesses the vehicle diagnostic system to re-invoke the learning mode. In this situation, wheel location information stored in the on-board vehicle system memory remains unchanged until the learning mode is invoked again. A weakness of this arrangement is that when an unexpected tire change is made (e.g., when a flat occurs) the information stored in the central electronics unit is no longer current.  
         [0005]     Accordingly, it is desirable to provide a system for detecting that a wheel change has taken place and updating the wheel ID and location information in the on-board vehicle electronics system memory without having to re-invoke the learning mode. In addition, it is desirable to be able to accomplish this without additional hardware and/or modification of the wheel mounted or vehicle mounted sensors, detectors, transmitters, receivers, ID units, and so forth. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.  
       BRIEF SUMMARY  
       [0006]     An apparatus is provided for detecting when a spare wheel (SP) is used to replace, e.g., after a flat, a normally rolling wheel on a vehicle, where each wheel can transmit wheel ID and motion status signals. The apparatus comprises a receiver for receiving the wheel signals, a memory for storing information relating wheel ID and wheel location on the vehicle, a processor coupled to the receiver and memory for analyzing the wheel signals to determine if the SP is rolling, and a timer coupled to the processor that measures how long the SP has been rolling. When the SP has been rolling for predetermined time T, the processor looks at the motion status signals from remaining wheels to determine which is stopped, and then modifies the information stored in the memory to associate the SP ID with a wheel location formerly occupied by the now stopped wheel and associate the stopped-wheel ID with a storage location for the spare.  
         [0007]     A method is provided for detecting when a spare wheel (SP) has replaced a normally rolling wheel on a vehicle, comprising, determining whether the SP is rolling and if so, starting a SP rolling timer. When the SP has been rolling for predetermined time T, then examining the motion status signal from remaining wheels to determine which wheel is now stopped, its ID and former location. Then associating a wheel ID for the SP with the former location of the stopped wheel and the stopped wheel ID with the stowage location of the SP. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and  
         [0009]      FIG. 1  is a simplified schematic diagram of a system comprising five vehicle wheels interacting with an on-board wheel data receiver, according to the prior art;  
         [0010]      FIG. 2  is a simplified schematic diagram of five vehicle wheels interacting with an on-board vehicle electronic system for monitoring wheel ID, location and status, according to the present invention; and  
         [0011]      FIG. 3  is a simplified flow chart illustrating the method of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0012]     The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.  
         [0013]     As used herein, the word “wheel” whether singular or plural is intended to be inclusive of the tire mounted thereon. For example, reference to data from a particular wheel is understood to include the desired information about the tire mounted thereon. Further the words “receiver” and “transmitter” or “sender” are not intended to be limited merely to signal incoming and outgoing functions, respectively, but are intended to include the meaning of “transceiver” that is, be capable of two-way wireless communication as the need arises. For convenience of explanation, it is assumed for purposes of the present invention that the learning mode has been completed and that each wheel is capable of transmitting its individual ID and its relevant function codes that define the wheel location on the vehicle and the wheel status, e.g., tire pressure, temperature, and so forth. The exact nature of the status information being transmitted by each wheel is not important to the present invention.  
         [0014]      FIG. 2  is a simplified schematic diagram of five vehicle wheels  10 A- 10 E interacting with on-board vehicle electronics system  20  comprising wheel data receiver  14  and data-processing sub-system  30 , for monitoring wheel ID, location and status, according to the present invention. RF signals  18 A- 18 E are transmitted by senders  11 A- 11 E of individual wheels  10 A- 10 E and received by on-board antenna  15  and receiver  14 . The learning mode is presumed to be complete so that signals  18 A- 18 E contain for each wheel, at least the wheel ID, location and status information. For convenience of explanation, reference number  10  is intended to refer to any and all of wheels  10 A- 10 E, reference number  11  is intended to refer to any and all of senders or transmitters  11 A- 11 E and reference number  18  is intended to refer to any and all of signals  18 A- 18 E. Further, for convenience of explanation and not intended to be limiting, signals  18  are referred to as comprising ID and “function code” information where the functions codes carry the status information (e.g., temperature, pressure, rotating or stationary, etc.).  
         [0015]     Receiver  14  demodulates signals  18  and sends the ID and function code information for each sending wheel to processor  16  via leads or bus  17 . Sub-system  30  further comprises speed sensor  24 , display  22  and memory  28 , coupled to processor  16  via leads or buses  23 ,  21 ,  25 , respectively. Processor  16  desirably but not essentially includes timer or timing function  26 . Timing function  26  may be a software timer or a hardware timer as a part of processor  16  or separate from processor  16 . Either arrangement is useful.  
         [0016]     The learning process is presumed to have been already accomplished according to arrangements described in the prior art (e.g., using individual wheel well transmitters sending location info to the wheel electronics) and each particular wheel ID has been associated with a wheel location, e.g., left front (LF), right front (RF), left rear (LR, right rear (RR) and spare (SP), and that information stored in memory  28 . Thus, during routine operation when signal  18  arrives with ID and status function codes, processor  16  is able to correlate the wheel ID with the wheel locations by retrieving the locations from memory for each wheel ID. Speed sensor  23  is conveniently included to provide processor  16  with information on the vehicle motion but this is not essential, since in most cases, the function codes received from the individual wheels will include an indication as to whether that wheel is moving or stationary.  
         [0017]     When a flat has occurred and the spare (SP) used to replace the flat tire, unless the learning mode is repeated, the location information stored in memory  28  is no longer correct and should be updated. The process flow in  FIG. 3  illustrates how system  20  of the present invention updates the location-ID correlation information stored in memory  28  without having to repeat the learn mode process. This is a significant advantage, especially with those automotive electronics systems where manual intervention is needed to initiate a learn mode sequence to correlate wheel IDs with altered wheel locations.  
         [0018]      FIG. 3  is a simplified flow chart illustrating method  100  of the present invention for determining whether the spare tire (SP) has been mounted on a rotating wheel (RW) position and vice-versa. For convenience of explanation and not intended to be limiting it is assumed that the data transmitted by each wheel and recovered in receiver  14  are assigned to particular fields (e.g., time slots) in the transmitted message, for example, that there is a data field for wheel ID, another data field for tire pressure data, a further data field for motion data, and so forth. This is intended to be merely exemplary and any method of encoding and distinguishing the wheel information and function codes may be used.  
         [0019]     Method  100  begins with START  102  that conveniently occurs on power up or at least when the vehicle begins to move as determined by speed sensor  24  or my examining the function codes on any message received from sender  11 . In RECEIVE SP SENDER MESSAGE step  104 , receiver  14  receives message  18  from sender  11  of the spare (SP) wheel, e.g., wheel  10 E. Method  100  then executes SP MOTION SENSOR ACTIVE? query  106  wherein it is determined whether or not the function codes contained in signal  18  from the spare, e.g., signal  18 E, show that the spare is rolling or stationary. This may be determined by processor  16  by, for example, comparing the function code received from wheel  10 E in the appropriate ‘motion’ field in detected signal  18 E with the function codes for ‘moving’ and/or ‘stationary’ stored in memory  28 . If the outcome of query  106  is NO (FALSE), that is, the spare is not moving, then VEHICLE IN MOTION? query  108  is executed wherein it is determined whether or not the vehicle is moving. Query  108  may be performed, for example, by processor  16  interrogating speed sensor  24  or by any other available means, as for example but not limited to, examining the ‘motion’ field codes of signals  18  received from other wheels  10 . If the outcome of query  108  is NO (FALSE), meaning that the vehicle is not moving, then as shown by path  109  method  100  returns to start  102  and initial query  104 . If the outcome of query  108  is YES (TRUE), then method  100  executes INITIALIZE USAGE TIMER step  110 , wherein timer  26  is set to an initial value, e.g., zero for a count-up timer and T for a count-down timer or whatever pother value is appropriate depending upon the type of timer used. Timer  26  is conveniently used to measure the amount of time that signal  18 E from the spare tire shows that the spare tire is ‘moving’. Persons of skill in the art will understand that INITIALIZE USAGE TIMER step  110  refers to setting timer  26  with the initial start value. Any type of counter or other timing arrangement may be employed. Thus, as used herein, the words “INITIALIZE USAGE TIMER” are intended to include any means of initializing a counter or timer of any type. Thereafter, method  100  returns again to start  102  and initial query  104 .  
         [0020]     Returning now to SP MOTION SENSOR ACTIVE? query  106 , if the outcome of query  106  is YES (TRUE) indicating that the spare (SP) wheel is moving, e.g., rotating, then SP USAGE TIMER ACTIVE? query  112  is executed wherein it is determined whether timer  26  or equivalent measuring how long the spare tire has been rotating, is active or not, i.e., still measuring motion time for the spare tire. If the outcome of query  112  is NO (FALSE) then method  100  proceeds to START USAGE TIMER step  114  wherein timer  26  or equivalent is started to measure the time during which the spare tire is in motion. Thereafter method  100  returns to start  102  and initial query  104  as shown by path  115 . Returning now to query  112 , if the outcome of query  112  is YES (TRUE) indicating that timer  26  is active (e.g., from a prior loop through step  114 ), then method  100  proceeds to SP USAGE TIMER EXPIRED? query  116 . If the outcome of query  116  is NO (FALSE) then method  100  returns to start  102  and initial query  104  as shown by path  117 . During first portion  118  of method  100 , processor  16  has determined that the spare wheel, e.g., wheel  10 E is in motion and has been in motion for predetermined time duration T measured by timer  26 . Steps  104 ,  106 ,  112 ,  116  of portion  118  repeat until either unit  11 E on spare wheel  10 E stops sending signal  18 E indicating that spare wheel  10 E continues in motion or until time T has expired. Time duration T is chosen to be greater than those accidental movements of spare tire  10 E as might from time to time occur in the life of the vehicle aside from mounting the spare on a rolling wheel location. About 5 to 60 minutes is suitable for time interval T with about 15 minutes being preferred. System  20  has now logically determined that the spare wheel, e.g., wheel  10 E, is no longer on the customary spare tire location, since where it still there it would not be in motion for time T.  
         [0021]     Knowing that the spare tire is no longer in its normal position, second portion  120  of method  100  determines where it has probably been placed by determining which of the four other tires is no longer moving. This is accomplished by processor  16  executing some or all of steps  122 - 136 . Steps  122 ,  126 ,  130 ,  134  may be executed in any order. For example, processor  16  examines the detected signal received from another of wheels  10 , e.g., the wheel correlated in memory  28  with the left-front (LF) wheel location on the vehicle, by executing LF SENDER STOPPED? query  122 . It does this, for example, by examining the ‘motion’ field code in the detected signal for that wheel. If the outcome of query  122  is YES (TRUE) indicating that that wheel is not moving, then in step  124 , processor  16  swaps the SP and LF sender IDs in memory  28  so that the ID for the spare is now correlated with the LF wheel location, and the ID for the LF wheel is now correlated with the SP location. Following step  124 , then as shown by path  125 , method  100  returns to start  102  and initial query  104 .  
         [0022]     If the outcome of query  122  is NO, them method  100  performs the same test on another wheel location, e.g., RF SENDER STOPPED? query  126 . If the outcome of query  126  is YES (TRUE) indicating that that wheel is not moving, then in step  128 , processor  16  swaps the SP and RF sender IDs in memory  28  so that the ID for the spare is now correlated with the RF wheel location, and the ID for the RF wheel is now correlated with the SP location. Following step  128 , then as shown by path  129 , method  100  returns to start  102  and initial query  104 .  
         [0023]     If the outcome of query  126  is NO, them method  100  performs the same test on another wheel location, e.g., RR SENDER STOPPED? query  130 . If the outcome of query  130  is YES (TRUE) indicating that that wheel is not moving, then in step  132 , processor  16  swaps the SP and RR sender IDs in memory  28  so that the ID for the spare is now correlated with the RR wheel location, and the ID for the RR wheel is now correlated with the SP location. Following step  132 , then as shown by path  133 , method  100  returns to start  102  and initial query  104 .  
         [0024]     If the outcome of query  130  is NO, them method  100  performs the same test on another wheel location, e.g., LR SENDER STOPPED? query  134 . If the outcome of query  134  is YES (TRUE) indicating that that wheel is not moving, then in step  136 , processor  16  swaps the SP and LR sender IDs in memory  28  so that the ID for the spare is now correlated with the LR wheel location, and the ID for the LR wheel is now correlated with the SP location. If the outcome of query  134  is NO, them method  100  conveniently but not essentially proceeds to SET ALARM step  138  wherein for example, processor  16  causes display  22  to indicate that a malfunction condition has occurred, since an ‘in motion’ outcome from all wheels including the spare indicates a malfunction in a vehicle with only four rolling wheels. Nevertheless, step  138  is not essential and in place of or following step  138 , method  100  returns to start  102  and initial query  104 . Those of skill in the art will appreciate that method  100  can include providing on display  22  a wheel status indication after any of steps  124 ,  128 ,  132 ,  136 ,  138  or any other step where such indication would be useful to the driver.  
         [0025]     While steps  120  are described in terms of swapping in memory  28  the SP ID with the ID of whichever of LR, RF, RR, LR wheel positions is not moving, this is merely one way of correcting the wheel ID-wheel location correlation information stored in memory  28  and is not intended to be limiting. Persons of skill in the art will understand based on the description herein that any way of correcting the wheel ID-wheel location correlation information may be used. What is important is that after method  100  is executed, the wheel IDs associated with the various wheel locations are correct, even though a new learn mode has not been executed. The present method does not depend upon re-executing a learn mode, but deduces the current wheel locations by executing method  100 . The wheel ID versus wheel location information stored in memory  28  is updated to accurately reflect the current situation. Thus, as used herein, the words “SWAP SP &amp; LF/RF/RR/LR SENDER ID LOCATIONS” are intended to encompass these alternative methods of correcting the wheel ID versus wheel location information stored in memory  28  or equivalent. It will also be noted that if no tire rotation-replacement has occurred, method  100  leaves the wheel ID versus wheel location information in memory  28  unchanged.  
         [0026]      FIGS. 1-3  depict the situation for a vehicle with four rolling wheels and one spare, for a total of five wheels. However, persons of skill in the art will understand that the present invention applies to a vehicle with any number of rolling wheels more or less than four. Thus, in the general case, the present invention applies to vehicles with two or more rolling wheels. The present invention is useful even when there are multiple spares provided that both are not changed at the same time. For example, in a vehicle with multiple spares, if one spare is swapped for a previously rolling wheel, e.g., because of a flat on that previously rolling wheel location, then method  100  corrects the wheel ID versus wheel location data stored in memory  28  for that post-flat situation. If subsequently, a further rolling wheel goes flat (e.g., in the same or another rolling wheel location) and a second spare is mounted in place of the new flat, then method  100  once again unequivocally corrects the wheel ID versus wheel location data in memory  28 . It does not matter how many spare wheels there are nor how many rolling wheels there are on the vehicle nor how many flats occur, method  100  will correct the wheel ID versus wheel location information without uncertainty as long as two or more previously rolling wheels are not replaced at the same time. This is a significant advantage, particularly with vehicles having larger numbers of rolling wheels and spares. When multiple spares are present, steps  118 ,  120  are repeated for each spare.  
         [0027]     When two (or more) flats occur at the same time and, for example, two spares are mounted at the same time before the vehicle resumes normal operation, method  100  can still determine useful information: specifically, that both simultaneously mounted spares are rolling and that two of the previously rolling wheels are now in the spare positions, but cannot determine unequivocally which spare has gone into which of the two replaced rolling wheel positions. Thus, the spare wheel IDs can be in either of two replaced rolling wheel locations, but not elsewhere. This information while not completely precise is useful because it can alert the driver to the fact that two spares are now rolling in either of two wheel locations. The larger the number of wheels on the vehicle, the more useful this information.  
         [0028]     When multiple spares are changed, steps  118 ,  120  are repeated for each spare. Where the multiple spares are mounted sequentially, then method  100  determines the spare locations exactly. Where two spares are mounted at the same time, then, on a first pass, method  100  will swap the ID of the first spare with the ID of the first location in steps  122 ,  126 ,  130 ,  134  leading to one of steps  124 ,  128 ,  132 ,  136 , and on a second pass it will swap the ID of the second spare with the next location in steps  122 ,  126 ,  130 ,  134  leading to one of steps  124 ,  128 ,  132 ,  136 . However, it cannot tell unequivocally which of the two newly mounted spares is in which of the two replaced rolling wheel position, but can tell that these spares are not on other rolling wheel positions.  
         [0029]     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.