DEVICE FOR AUTOMATICALLY DETECTING ABNORMAL CONDITIONS IN VEHICLE TIRES
First Claim
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1. In a device for automatically detecting the loss of pressure and the abnormal increase of temperature within a pneumatic tire of wheeled vehicle, having a normally closed pressure switch to be opened when pressure in the tire is below a predetermined pressure value;
- a normally closed temperature switch to be opened when temperature of the tire is above a predetermined temperature value;
coupling means comprising a primary coil and a secondary coil, the secondary coil being secured concentrically on an axle of the vehicle for rotation therewith and being electrically connnected in series with said pressure switch and said temperature switch, the primary coil being secured rigidly with respect to the frame of the vehicle and concentrically with respect to the secondary coil so that the primary coil exhibits an inductance change upon open of said switches; and
warning means;
a clock pulse generator to produce clock pulses;
a first flip-flop connected to said clock pulse generator for providing, as its output, frequency division of said clock pulses;
a second flip-flop connected to said first flip-flop for providing, as its output, further frequency division of said clock pulses;
resistor electrically connecting said second flip-flop to said primary coil of said coupling means;
comparator gate means responsive to a voltage at a junction point between said resistor and said primary coil of said coupling means for providing a pulse output when said voltage is above a reference voltage;
AND logical function gate means connected to said first flipflop and to said comparator gate means to receive outputs thereof, respectively, said AND logical function gate means being operable to provide a pulse output responsive to coincidence of inputs thereto; and
means responsive to said output pulse of said AND logical function gate means for energizing said warning means.
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Abstract
A pressure switch and a PTC (Positive Temperature Coefficient) thermistor acting as a temperature switch, which are mounted within the tire assembly to detect certain abnormal conditions in the tire, such as too low air pressure and excessive tire temperature. Both switchs are connected in series to an electromagnetic coupling unit comprising a primary coil and a secondary coil. The secondary coil is secured concentrically on an axle of the vehicle for rotation therewith. The primary coil is secured rigidly on the journal member of the axle in concentric relation with the secondary coil, so that when the abnormal conditions occur, the primary coil exhibits a marked inductance increase. In response to the marked inductance increase, a detector unit produces a voltage signal which is supplied to an alarm lamp or buzzer for the driver'"'"''"'"'s attention.
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Citations
3 Claims
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1. In a device for automatically detecting the loss of pressure and the abnormal increase of temperature within a pneumatic tire of wheeled vehicle, having a normally closed pressure switch to be opened when pressure in the tire is below a predetermined pressure value;
- a normally closed temperature switch to be opened when temperature of the tire is above a predetermined temperature value;
coupling means comprising a primary coil and a secondary coil, the secondary coil being secured concentrically on an axle of the vehicle for rotation therewith and being electrically connnected in series with said pressure switch and said temperature switch, the primary coil being secured rigidly with respect to the frame of the vehicle and concentrically with respect to the secondary coil so that the primary coil exhibits an inductance change upon open of said switches; and
warning means;
a clock pulse generator to produce clock pulses;
a first flip-flop connected to said clock pulse generator for providing, as its output, frequency division of said clock pulses;
a second flip-flop connected to said first flip-flop for providing, as its output, further frequency division of said clock pulses;
resistor electrically connecting said second flip-flop to said primary coil of said coupling means;
comparator gate means responsive to a voltage at a junction point between said resistor and said primary coil of said coupling means for providing a pulse output when said voltage is above a reference voltage;
AND logical function gate means connected to said first flipflop and to said comparator gate means to receive outputs thereof, respectively, said AND logical function gate means being operable to provide a pulse output responsive to coincidence of inputs thereto; and
means responsive to said output pulse of said AND logical function gate means for energizing said warning means.
- a normally closed temperature switch to be opened when temperature of the tire is above a predetermined temperature value;
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2. A device as claimed in claim 1 in which said normally closed temperature switch is in the form of a thermistor, said thermistor having its critical temperature approximately equal to a predetermined temperature above which the tire is deemed to be in the abnormal condition.
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3. A device as claimed in claim 1 in which said normally closed temperature switch is in the form of a bimetal.
Specification
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Current AssigneeAkio Hosaka, Kiyoshi Wazawa
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Original AssigneeAkio Hosaka, Kiyoshi Wazawa
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InventorsHosaka, Akio, Wazawa, Kiyoshi
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Primary Examiner(s)Caldwell, John W.
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Assistant Examiner(s)Nowicki, Joseph E.
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Application NumberUS05/302,721Time in Patent Office762 DaysField of Search340/58,57,60,228 200/61.22,61.25 73/146.5,146.8US Class Current340/448CPC Class CodesB60C 23/0408 transmitting the signals by...B60C 23/0427 Near field transmission wit...B60C 23/0428 using passive wheel mounted...B60C 23/20 Devices for measuring or si...G01K 1/024 for remote indicationH01H 35/28 Compensation for variation ...
