Tire inner pressure drop alarming service

• US 4,300,118 A
• Filed: 02/15/1979
• Issued: 11/10/1981
• Est. Priority Date: 02/28/1978
• Status: Expired due to Term

• Current Assignee: Bridgestone Tire Company Limited (Bridgestone Corporation), Mitaka Instrument Company Limited
• Original Assignee: Bridgestone Tire Company Limited (Bridgestone Corporation), Mitaka Instrument Company Limited
• Inventors: Nishino, Hiroshi, Matsuda, Akira, Iwasaki, Motoaki, Yasuda, Shigeo, Goshima, Norio
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): Nowicki, Joseph E.
• Application Number:
  US06/012,481
• Time in Patent Office: 999 Days
• Field of Search: 340/58, 200/61.25, 73/146.5
• US Class Current: 340/448
• CPC Class Codes: B60C 23/0428 using passive wheel mounted resonance circuits
• CPC Class Codes: B60C 23/0498 for rim attachments B60C23/0494, B60C23/0496 take precedence

Abstract

A tire inner pressure drop alarming device comprises an oscillation section mounted on a vehicle body in the vicinity of a vehicle wheel, a resonance section mounted on a peripheral portion of a tire and including a resonance coil, a signal processing and alarming section mounted on the vehicle body in spaced relation with the vehicle wheel, and a coaxial cable connecting the oscillation section and the signal processing and alarming section. The resonance coil has a major length measured in the direction of rotation and longer than a minor length of the resonance coil in a direction perpendicular to the direction of rotation. The ratio of the minor length to the major length ranges from 0.2 to 1.0.

Claims

1. A tire inner pressure drop alarming device for transforming an abnormal pressure drop of a tire into an electric signal to alarm a driver, which comprises:

an oscillation section mounted on a vehicle body in the vicinity of a vehicle wheel and including an oscillation coil and an oscillating capacitor, the oscillation state of radial magnetic energy in said oscillation coil changing in response to said abnormal pressure drop;

a resonance section mounted on a peripheral portion of said vehicle wheel in the vicinity of said oscillation coil, and including a resonance coil resonating said magnetic energy generated from said oscillation coil, a resonating capacitor and a pressure detecting switch in response to the abnormal pressure drop of said tire, said resonance coil having an elongated cross-section disposed in a plane perpendicular to magnetic lines of force between said resonance coil and oscillation coil generated when said resonance coil is brought into face-to-face relation with said oscillation coil and parallel with a plane separating said resonance coil and said oscillation coil, said cross-section having a major length, measured in the rotational direction of said resonance coil rotated together with said vehicle wheel, longer than a minor length measured in the direction perpendicular to said rotational direction of said resonance coil with a value obtained by dividing said minor length by said major length being no less than 0.2 and less than 1.0;

a signal processing and alarming section mounted on said vehicle body in spaced relation with said vehicle wheel, and including an oscillation circuit cooperating with said oscillation section for effecting an oscillating action by radiating said magnetic energy from said oscillation section to change said oscillation state in cooperation with said oscillation section in response to said abnormal pressure drop, a detecting circuit detecting an output of said oscillation circuit, a comparison circuit for comparing the output of said detecting circuit with a standard signal to generate a plurality of output pulses, an integration circuit for integrating said output pulses of said comparison circuit, a logical circuit for logically calculating an output generated from said integration circuit, an alarming means for emitting an alarm with an output generated from said logical circuit, and a power source switch; and

a coaxial cable connecting said oscillation section and signal processing and alarming section.

2. A tire pressure drop alarming circuit as set forth in claim 1, wherein said detecting circuit is an amplitude detecting circuit.

3. A vehicle tire pressure alarm device for transforming an abnormal tire pressure into an electric signal to alarm a driver, which comprises:

means mounted on the body of said vehicle near a wheel of said vehicle for radiating a magnetic field;

a unit mounted on a peripheral portion of said vehicle wheel including means for absorbing energy from said magnetic field on selected revolutions of said tire and switch means for detecting said abnormal tire pressure and controlling said absorption in response to said detecting, said absorbing means including a resonance coil having an elongated cross-section disposed in a plane perpendicular to magnetic lines of force between said resonance coil and said radiating means generated when said resonance coil is brought into face-to-face relation with said radiating means and parallel with a plane separating said resonance coil and said radiating means, said cross-section having a major length, measured in the rotational direction of said resonance coil rotated together with said vehicle wheel, longer than a minor length measured in the direction perpendicular to said rotational direction of said resonance coil with a value obtained by dividing said minor length of said major length being no less than 0.2 and less than 1.0; and

a signal processing and alarm section mounted on said vehicle body remote from said radiating means, and including means in combination with said radiating means for generating an oscillating signal, means for detecting the amount of energy in said magnetic field, means for comparing the energy in said magnetic field during said selected revolutions with the energy in said magnetic field during non-selected revolutions and for generating a plurality of output pulses during one of selected and non-selected revolutions, an integration circuit for integrating said output pulses of said comparing and generating means, a logic circuit for logically producing a signal from the output of said integration circuit upon detection of said abnormal tire pressure, and means for emitting an alarm in response to said signal from said logic circuit.

4. A vehicle tire pressure alarm device as set forth in claim 3, wherein said detecting means is an electrical signal amplitude detecting circuit.