Apparatus for indicating parameters sensed on a rotatable wheel

A tire inflation pressure sensor comprising:

• a coil mounted on the stationary structure of a vehicle adjacent a wheel mounted on an axle of said vehicle;
• pressure sensitive means mounted on said wheel to rotate therewith in an orbital manner for responsing to the inflation pressure of a tire and for electro-magnetically interacting with said coil in accordance with said inflation pressure, said coil being formed by at least one loop oriented so that it faces the path traveled by said pressure-sensitive means as said wheel rotates and produces a directional magnetic field extending toward said path, said field extending in a direction other than toward said axle;
• and
• interrogation means mounted on said non-rotatable structure for supplying a signal to said coil and for measuring the combined electrical response of said pressure sensitive means and said coil.

In a conveyance having at least one rotatable wheel with an inflatable tire thereon and a non-rotatable structure on which said wheel is supported, a tire inflation pressure sensor comprising:

• a resonant circuit mounted on said wheel including pressure sensitive means for varying the resonant frequency of said circuit in accordance with the inflation pressure of said tire;
• a ring-shaped coil mounted on said non-rotatable structure concentric with the axis of rotation of said wheel for interaction with said resonant circuit, said coil including a series of loops arranged in a circular array, each of said loops being wound about an axis substantially perpendicular to said array and directed toward the path traveled by said resonant circuit as said wheel rotates;
• and
• interrogation means connected to said coil for supplying a signal to one of said components and for measuring the combined response of said coil and said resonant circuit to a cyclically varying signal thereby determining the inflation pressure of said tire.

In a conveyance having at least one rotatable wheel with an inflatable tire thereon and a non-rotatable structure on which said wheel is supported, a tire inflation pressure sensor comprising:

• a resonant circuit mounted on said wheel including a capacitor, an inductor and pressure sensitive means responsive to the inflation pressure of said tire for varying the impedance of said inductor in accordance with the inflation pressure and thereby varying the resonant frequency of said circuit;
• a ring-shaped non-rotatable coil mounted on said non-rotatable structure concentric with the axis of rotation of said wheel for impedance varying interaction with said resonant circuit, said coil including a plurality of loops arranged in a circular array, each of said loops being wound about an axis substantially perpendicular to said array to produce a magnetic field, said coil extending along the path traveled by said resonant circuit as said wheel rotates so that said resonant circuit is at all times aligned with said field;
• interrogation means connected to said coil for measuring the combined electrical response of said coil and said resonant circuit to a cyclically varying signal and thereby determining the inflation pressure of said tire;
• and
• display means responsive to said interrogation means for providing information relating to said inflation pressure.

An apparatus for providing on the non-rotatable structure of a vehicle a signal representing a parameter measured on a rotatable wheel of said vehicle, said apparatus comprising:

• a first coil mounted on said wheel of said vehicle for rotation therewith;
• a second coil mounted on said non-rotatable structure of said vehicle adjacent to said first coil;
• said first and second coils each being of a configuration such that they produce directional magnetic fields extending towards each other and each forming at least a portion of a ring;
• circuit means for varying the combined impedance of said coils and said circuit means in accordance with said parameter;
• and
• interrogation means mounted on said non-rotatable structure for measuring the combined electrical response of said coils and said circuit means.

In a conveyance having at least one rotatable wheel with an inflated tire thereon and a non-rotatable supporting structure on which said wheel is mounted, a tire inflation pressure sensor comprising:

• a resonant circuit mounted on said wheel including a capacitor of fixed capacitance, a variable inductor, and pressure-sensitive means responsive to the inflation pressure of said tire for varying the inductance of said inductor in accordance with said inflation pressure and thereby varying the resonant frequency of said circuit, said pressure sensitive means including a movable member exposed to the inflation pressure of said tire and a resilient means for biasing said member toward the interior of said tire;
• a ring-shaped coil mounted on said non-rotatable structure concentric with the axis of rotation of said wheel for impedance varying interaction with said resonant circuit, said coil including a plurality of loops electrically connected in series and arranged in a circular array, each of said loops being wound about an axis substantially perpendicular to said array to produce an annular force field, said coil extending along the path traveled by said resonant circuit as said wheel rotates so that said resonant circuit is at all times aligned with said force field;
• interrogation means connected to said coil for measuring the combined impedance of said coil and said resonant circuit with respect to a cyclically varying signal and thereby determining the inflation pressure of said tire;
• and
• display means mounted on an instrument panel of said conveyance and responsive to said interrogation means for providing a visual indication relating to said tire pressure.