Pressure monitor for vehicle tire

Details Pressure monitor for vehicle tire Pressure monitor for vehicle tire

1999-09-20

2001-07-10

Wu, Daniel J. (Department: 2736)

Communications: electrical

Land vehicle alarms or indicators

Internal alarm or indicator responsive to a condition of the...

C340S447000, C340S442000

Reexamination Certificate

active

06259360

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a pressure monitor and a method of controlling the pressure monitor for a tire on a vehicle. The pressure monitor comprises a signal receiving device and a signal sending device including a tire pressure sensor and a battery.
BACKGROUND OF THE INVENTION
One example of a pressure monitor for a vehicle tire is disclosed in Japanese Laid-Open Patent Application No. 9-30220. This conventional pressure monitor comprises a signal sending device installed on a wheel of a vehicle for sending an electric wireless signal indicating a tire pressure at predetermined intervals, and a signal receiving device installed on a body of the vehicle for receiving the electric wireless signal sent by the signal sending device. Consequently, the conventional pressure monitor keeps watch on the tire pressure of the vehicle, and can issue an alarm when the tire pressure is less than a predetermined alarm tire pressure.
The signal sending device of the conventional pressure monitor is attached to the wheel, and a battery, which is a power source for the signal sending device, is contained in the signal sending device. Electric power is consumed when the signal sending device sends an electric signal. Therefore, it is desirable to restrain the signal sending frequency in order to lengthen the life of the battery. Consequently, the pressure monitor adopts such a control as, when the detected tire pressure changes a little bit, the signal sending device interrupts to send the electric signal of the detected tire pressure.
In such an above-mentioned control, however, in the case that the tire pressure, which is equal to or marginally higher than the alarm tire pressure, gradually decreases (at a small changing rate), the electric signal of the tire pressure will not be sent, even though the present tire pressure is lower than the alarm tire pressure. The signal receiving device, thus, does not issue an alarm in such a necessary situation.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to solve the aforementioned problems. It provides a pressure monitor and a method of controlling the pressure monitor for a vehicle tire which reduces the electric power consumed by a signal sending device in the pressure monitor and at the same time enables the pressure monitor to issue an alarm reliably when the tire pressure is lower than an alarm tire pressure.
To achieve at least a part of the aforementioned objects, a pressure monitor and a method of controlling the pressure monitor for a vehicle tire of the present invention have found a solution, which will now be described.
A pressure monitor for a vehicle tire has a signal sending device and a signal receiving device. The signal sending device includes a battery and a tire pressure sensor, and sends an electric signal in response to a tire pressure detected by the pressure sensor. The signal receiving device receives the electric signal sent by the signal sending device. Furthermore, the signal sending device sends electric signals at predetermined sending intervals and sends an electric signal if a change in the value of the tire pressure in a predetermined unit of time is equal to or more than a predetermined standard value.
Since the signal sending device sends electric signals at predetermined sending intervals in this pressure monitor, the signal receiving device can detect the tire pressures from the electric signals at least at predetermined intervals. If the change in the value of the tire pressure in the unit time is equal to or more than the standard value, the tire pressure might not be normal. Since the electric signal of the detected tire pressure is sent by the signal sending device even though in such a case, the signal receiving device can detect the abnormality of the tire pressure. If the change is less than the standard value, the signal sending device sends the signal only at the periodical intervals. Then, the pressure monitor can save electric power consumed by the signal sending device.
Furthermore, the signal sending device sends the electric signal to the signal receiving device if an average of the change in the value of the tire pressure in a standard time is equal to or more than the standard value. The standard time can be determined to be equal to n2×&dgr;t by selecting a value n2 which is equal to or less than n1 (=&Dgr;T/&dgr;t) calculated from the predetermined sending interval &Dgr;T and the predetermined unit time &dgr;t, and multiplying the value n2 by the predetermined unit time &dgr;t.
The signal receiving device further includes at least one alarm for issuing an alarm on the basis of comparing the tire pressure detected by the tire pressure sensor with a predetermined alarm tire pressure. The signal receiving device issues an alarm when the detected tire pressure is equal to or less thin the predetermined alarm tire pressure. Then the pressure monitor can reliably issue an alarm, when the detected tire pressure becomes equal to or less than the alarm tire pressure.
In this pressure monitor, the standard value is determined on the basis of the predetermined sending intervals and the predetermined alarm tire pressure. Therefore, the standard value can be set to be a value by which the signal receiving device can swiftly catch the time when the tire pressure is equal to or lower than the alarm tire pressure. Consequently, the signal sending device sends the electric signal, only when the alarm should be issued with high possibility. Then, consumed electric power of the sending signal device becomes further lower.
In the case that a plurality of alarm pressures are provided in the signal receiving device, the standard value can be determined on the basis of the tire pressure which is equal to or more than the minimum value among a difference between a predetermined normal tire pressure and the highest alarm tire pressure and the differences between pairs of successive alarm tire pressures. The standard value can also be determined on the basis of the tire pressure which is equal to or less than the difference between the predetermined normal tire pressure and the lowest alarm tire pressure.


REFERENCES:
patent: 4909074 (1990-03-01), Gerresheim et al.
patent: 5285189 (1994-02-01), Nowicki et al.
patent: 5559484 (1996-09-01), Nowicki et al.
patent: 5600301 (1997-02-01), Robinson, III
patent: 5774048 (1998-06-01), Achterholt
patent: 5900809 (1999-05-01), Hebert
patent: 5965808 (1999-10-01), Normann et al.
patent: 6112165 (2000-08-01), Uhl et al.
patent: 8-227492 (1996-09-01), None
patent: 9-30220 (1997-02-01), None
patent: WO 94/06640 (1994-03-01), None
patent: WO 96/06747 (1996-03-01), None

Affiliated with

Also associated with

Rating

Pressure monitor for vehicle tire does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Pressure monitor for vehicle tire, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pressure monitor for vehicle tire will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2496416