Measuring and testing – Tire – tread or roadway
Reexamination Certificate
2002-02-11
2003-06-24
Lefkowitz, Edward (Department: 2855)
Measuring and testing
Tire, tread or roadway
C073S146500, C073S146300, C340S447000
Reexamination Certificate
active
06581449
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application relates to commonly-owned, PCT Patent Application No. PCT/US99/18610 filed Aug. 16, 1999.
TECHNICAL FIELD OF THE INVENTION
The invention relates generally to systems for measuring air pressure in pneumatic tires of vehicles and, more particularly, to systems including a sensor and a transponder associated with each of the vehicle tires.
BACKGROUND OF THE INVENTION
Safe, efficient and economical operation of a motor vehicle depends, to a significant degree, on maintaining the correct air pressure in the tires of the motor vehicle. Failure to correct promptly for faulty/abnormal (typically low) air.pressure may result in excessive tire wear, blow-outs, poor gasoline mileage and steering difficulties.
The need to monitor tire pressure is highlighted in the context of “run-flat” (driven deflated) tires, tires which are capable of being used in a completely deflated condition. Such run-flat tires, as disclosed for example in commonly-owned U.S. Pat. No. 5,368,082, incorporated in its entirety by reference herein, may incorporate reinforced sidewalls and mechanisms for securing the tire bead to the rim to enable a driver to maintain control over the vehicle after a catastrophic pressure loss, and are evolving to the point where it is becoming less and less noticeable to the driver that the tire has become deflated. The broad purpose behind using run-flat tires is to enable a driver of a vehicle to continue driving on a deflated pneumatic tire for a limited distance (e.g., 50 miles, or 80 kilometers) prior to getting the tire repaired, rather than stopping on the side of the road to repair the deflated tire. Hence, it is generally desirable to provide a low pressure warning system (LPWS) within the vehicle to alert (e.g., via a light on the dashboard, or a buzzer) the driver to the loss of air in a pneumatic tire.
FIG. 1
illustrates a typical low pressure warning system (LPWS)
100
of the prior art installed on a motor vehicle
102
(shown in dashed lines) having four pneumatic tires
104
a
. . .
104
d
installed on four respective wheels (not shown). A transponder (“TAG”)
106
a
. . .
106
d
is associated with each of the tires
104
a
. . .
104
d
, respectively.
As used herein, a “transponder” is an electronic apparatus (device) capable of both receiving and transmitting radio frequency signals, and impressing variable information (data) in a suitable format upon the transmitted signal indicative of a measured condition (e.g., tire pressure) or conditions (e.g., tire pressure, temperature, revolutions), as well as optionally impressing fixed information (e.g., tire ID) on the transmitted signal, as well as optionally responding to information which may be present on a signal which is received by the transponder.
“Passive” transponders are transponders powered by the energy of a signal received from an external “interrogator” apparatus. “Active” transponders are transponders having their own power supply (e.g., a battery), and include active transponders which remain in a “sleep” mode, using minimal power, until “woken up” by a signal from an interrogator.
The transponders
106
a
. . .
106
d
are suitably passive transponders which obtain their operating power from an RF signal which is provided by an on-board interrogator
108
which is mounted within the vehicle.
The interrogator
108
comprises an RF transmitter
112
(e.g., for powering passive transponders), an RF receiver
114
, control logic
116
which may include a microprocessor (&mgr;P), and a display device
118
such a visual display and optionally including an audible alarm. Antennas (“ANT”)
110
a
. . .
110
d
are disposed on the vehicle
102
, preferably adjacent the tires
104
a
. . .
104
d
, respectively, such as in the wheel wells of the vehicle. The antennas
110
a
. . .
110
d
are suitably ferrite loopstick antennas.
The use of multiple vehicle antennas
110
a
. . .
110
d
, each at a fixed position on the vehicle adjacent a respective tire
104
a
. . .
104
d
, such as in the wheel well, is well known, and is disclosed in U.S. Pat. Nos. 3,553,060; 3,810,090; 4,220,907; 4,319,220; and 5,774,047, all of which are incorporated in their entirety by reference herein. In this manner, close coupling can be effected between the tire transponders and the vehicle antennas, thereby facilitating identifying which of the several wheels on a vehicle has a sensed low pressure condition.
In use, the interrogator
108
powers the transponders
106
a
. . .
106
d
which, in turn, transmit data indicative of a measured condition (e.g., tire air pressure) back to the interrogator
108
. In any such system, it is desirable to have efficient and effective coupling of signals between the fixed antennas
110
a
. . .
110
d
(alternatively, one centrally-located fixed antenna) and the moving (i.e., when the vehicle is in motion) transponders (each of which has its own antenna, not shown).
Low pressure warning systems for tires are generally well known, and representative examples may be found in the following U.S. Patents, all of which are incorporated in their entirety by reference herein: U.S. Pat. No. 3,694,803 (Strenglein; 1972); U.S. Pat. No. 4,067,235 (Markland, et al.; 1978); U.S. Pat. No. 4,334,215 (Frazier, et al.; 1982); and U.S. Pat. No. 5,335,540 (Bowler, et al.; 1994).
An important feature of a viable low pressure warning system employing transponders and an interrogator is providing effective coupling of radio frequency (RF) signals between the transponders which may be located inside of the pneumatic tires, and the interrogator which may be located at some central location in the vehicle. An additional important feature of a viable low pressure warning system is providing an indication to the operator of the vehicle of the condition being monitored, for example, low tire pressure, correct tire pressure, etc.
For example, a straightforward approach is to have an RF transmitter and pressure sensor within each tire (e.g., affixed to the valve stem thereof). In order to save power, the transmitter may only transmit when pressure drops below a threshold value. A single, centrally-located receiver in the vehicle cab can detect the transmission, and cause an audible signal to be sounded to alert the driver to the sensed low pressure condition. In such a system, the RF transmissions from the transmitters must be adequate to penetrate vehicle components to be detected by the receiver. Generally, no hard wiring from the vicinity of the wheels to the receiver is required when utilizing such an RF communications link. When relying on robust RF coupling between the individual transmitters (or transponders) and a central receiver (or interrogator), techniques should be provided to prevent “false alarms”, such as a low tire pressure signal emitted by a transmitter of another vehicle in close proximity to the vehicle in question. Additionally, it is sometimes desirable to be able to ascertain which of the several (e.g., four) tires on a given vehicle has a sensed low pressure condition.
U.S. Pat. No. 3,533,060 (Garcia; 1970), incorporated in its entirety by reference herein, describes a pressure-responsive radio transmitter (13) disposed on each valve stem (21) of each tire (12) of a vehicle (11).
“Receiving antennas 16 are mounted in each of the wheel wells and connected by appropriate leads to a receiver set 17 mounted on or attached to the dashboard of the vehicle 11 . . . the receiver set can be of standard construction and include amplifying means to amplify the signals picked up by the antennas 16 and means for indicating the occurrence of such transmission, in the form of a buzzer, a bell, a light, or the like.” (column 2, lines 30-38)
U.S. Pat. No. 4,220,907 (Pappas, et al.; 1980), incorporated in its entirety by reference herein, discloses a low tire pressure alarm system for vehicles such as trucks and cars. Each wheel is provided with a transmitter (200). A common receiver (300) has either a single receiving antenna, or multiple antennas, with each w
Brown Robert Walter
Dunn William Frank
Cohn Howard M.
Ellington Alandra
Lefkowitz Edward
The Goodyear Tire & Rubber Company
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