Communications: electrical – Land vehicle alarms or indicators – Internal alarm or indicator responsive to a condition of the...
Reexamination Certificate
1998-05-18
2001-01-30
Tong, Nina (Department: 2736)
Communications: electrical
Land vehicle alarms or indicators
Internal alarm or indicator responsive to a condition of the...
C340S442000
Reexamination Certificate
active
06181241
ABSTRACT:
BACKGROUND OF THE INVENTION
Previously-known tire pressure monitoring systems include a pressure sensor, transmitter, and transmission antenna, with respective allocated receiving antennas and a central electronic analysis system on the vehicle body. The problem that arises with tire pressure monitoring systems of this kind is unequivocal allocation of the transmitters to the respective wheel position. In the past, the problem of position recognition is was solved as follows-the transmitters generate a signal divided into four segments, consisting of preface, identification signal, measurement signal, and conclusion. The central electronic analysis system can recognize the position based on the identification signal. Doing so, however, first requires first performing an initialization during which the respective identification signal, linked to the respective position, is stored by the central electronic analysis system. To perform this initialization, the system must be switched into a “pairing” mode, and each individual transmitter must then be activated once in sequence. The system is then switched back into measurement mode until the transmitter positions change, e.g. if a wheel is changed. This means, however, that a suitably trained person must perform this initialization each time a wheel is changed. In some circumstances it is therefore impossible, or possible only at the cost of safety, to perform a wheel change at any repair shop or at home. Flawless operation of the system cannot be guaranteed due to potential operating errors.
In another known system, the problem is circumvented by recording the data for the pressure sensors and the transmission electronics connected to them by means of a remote-control element instead of by means of the central electronic system. The remote-control element comprises an LCD display device which makes it possible to read the tire pressure. To determine the tire pressure, the desired information must be interrogated at each individual wheel by means of the remote-control element. Although this method offers the advantage of an unequivocal allocation of readings, it does not allow tire pressure to be checked while driving.
SUMMARY OF THE INVENTION
The object of the present invention is therefore to develop a method for position recognition which demands no special abilities of even inexperienced mechanics or automobile owners when it is necessary, after wheels are first mounted and after a wheel change, to recognize, on the basis of the signals with different identifiers which are emitted from multiple wheels, which signals derive from the vehicle's own wheels. The intent is to rule out any failure due to possible operating errors.
According to the invention, a central electronic analysis system records the intensities at which the same transmitter is received at a receiving antenna. These values are then compared, multiple successively received signals are taken into consideration in order to avoid incorrect allocations. An average can then be taken of the multiple signals, or a simple count is made of how often the event occurs in which a specific antenna most strongly receives a transmitter, i.e. a signal with a specific identifier. Based on the average or the greatest number of events, the transmitter transmitting with that identifier, or the pertinent wheel, is then classified as belonging to the local vehicle, and the identifier is stored in the central receiving and electronic analysis system as the identifier of a local wheel. The procedure is the same for the second-strongest signal, third-strongest signal, etc., until the Nth-strongest signal has been identified, N being the number of wheels mounted on the vehicle, which can include an onboard spare wheel if it is housed so that the signals emitted by it are not too strongly shielded. If a spare wheel in the trunk is so strongly shielded that the signals emitted by it cannot be received more strongly than the signals proceeding from adjacent vehicles, the spare wheel should then not be included in the recognition process of the invention.
If the vehicle has, for example, four wheels, then according to he invention the four strongest signals with four different identifiers are determined and stored; taking a spare wheel into consideration, there may also be five identifiers for the total of five wheels. If additional signals are received thereafter, having an identifier which does not match any of the stored identifiers, these are not taken into account—or are taken into account in subordinate fashion in the tire pressure monitoring process.
If a distinction is to be made between running wheels of a vehicle and one or more spare wheels being carried in the vehicle, this is advantageously possible by means of the invention.
Signals which derive from transmitters located on wheels which are rotating (running wheels) are received with fluctuating signal levels because the location of the transmitter relative to the receiving antenna changes cyclically as a result of the wheel rotation. The situation is different for onboard spare wheels. When signals emitted from a spare wheel are received, they do not exhibit the fluctuations in signal level resulting from vehicle motion. This makes it possible to find an additional criterion by which to distinguish between signals coming from a spare wheel and signals coming from running wheels. If, while the vehicle is in motion, a received signal does not exhibit any of the fluctuations in signal level caused by wheel rotation, it may be concluded therefrom that it derives from an onboard spare wheel and not from a running wheel, even if that signal whose level exhibits no motion-related fluctuations is received at by the receiving antenna at the greatest intensity. Such a signal is either allocated to a spare wheel or is left entirely out of consideration (the latter, in particular, if onboard spare wheels are not intended to be monitored). This development of the invention has the advantage that the risk of erroneous allocations is once again reduced. This is true particularly with regard to those running wheels which are located at approximately the same distance as, or farther away than, the spare wheel, so that the signal emitted from the spare wheel is received at approximately the same intensity as, or a higher intensity than the signals emitted from a running wheel. The development of the invention ensures that an erroneous allocation does not occur even in this unfavorable case.
This method is useful not only when as is usual, a single spare wheel is carried on board, but also when multiple replacement wheels are carried. When additional wheels with snow tires are carried in the trunk, for example, the signals emitted by them cannot disrupt the correct allocation of the running wheels to their receiving antennas.
Another possibility for distinguishing between signals coming from rotating wheels and signals coming from replacement wheels involves use of the fact that in the initial phase of vehicle motion after motion begins, the tire temperature generally rises due to flexing. This is not the case with a spare wheel, since its tire is not flexed. If a temperature sensor is provided in the tire pressure monitoring system at each wheel in addition to the pressure sensor, and if the signal emitted by the transmitter on the wheel transfers information not only about tire pressure but also about tire temperature, a temperature rise signaled after vehicle motion begins can then be evaluated as an indication that the signal derives from a rotating wheel and not from a spare wheel.
It is sufficient if the vehicle has only a single receiving antenna, which is housed at a suitable point on the underside of the body or chassis so that it can receive signals at sufficient intensity from all the wheels attached to the vehicle. It is also possible, however, to allocate a separate antenna to each wheel in the latter's vicinity. In this case the ranking of the intensity at which the signals are received by the various antennas will diffe
Kessler Ralf
Normann Norbert
Schulze Gunter
Beru Aktiengesellschaft
Orum & Roth
Tong Nina
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