Mechanical-electromagnetic pressure sensor

• US 4,597,286 A
• Filed: 11/29/1983
• Issued: 07/01/1986
• Est. Priority Date: 11/29/1983
• Status: Expired due to Fees

• Current Assignee: Gianluigi Aguglia
• Original Assignee: Gianluigi Aguglia
• Inventors: Aguglia, Gianluigi
• Primary Examiner(s): WOODIEL, DONALD
• Application Number:
  US06/556,154
• Time in Patent Office: 945 Days
• Field of Search: 73/146.5, 73/146.4, 73/146.8, 73/728, 340/58
• US Class Current: 73/146.5
• CPC Class Codes: B60C 23/0428 using passive wheel mounted resonance circuits
• CPC Class Codes: B60C 23/043 using transformer type signal transducers, e.g. rotary transformers

Abstract

The present invention is a remote system for indicating tire pressure which includes a mechanical electromagnetic pressure sensor which is disposed outside a pneumatic tire which is mounted on a wheel rim. The mechanical electromagnetic pressure sensor includes a bellows which is fluidly coupled to the pneumatic tire through the wheel rim and a ferrite rod which is fixedly coupled to the bellows. The mechanical electromagnetic pressure sensor includes a pointer which is mechanically coupled to the bellows and indexing plate which provides a linear scale of the position of the pointer, the indexing plate is disposed adjacent, but not contiguous to the pointer so that the scale of the indexing plate mechanically provides a direct and visual reading of the pressure in the pneumatic tire. The remote system also includes a passive circuit having a first coil which is mechanically coupled to the wheel rim and a second coil which is electromagnetically coupled to the ferrite rod, which is slidably coupled to the second coil, all of which are electrically coupled to form a tuned circuit which resonates at a particular frequency which is dependent on the position of the ferrite rod. The remote system also includes a probe which detects the change in frequency at which the passive circuit resonates in order to provide a measure of movement of the ferrite rod in response to the change in pressure of the pneumatic tire.

Claims

1. A remote system for indicating tire pressure including a mechanical electromagnetic pressure sensor which is disposed outside a pnuematic tire which is mounted on a wheel rim, said remote system comprising:

a. a bellows which is fluidly coupled to said pneumatic tire through said wheel rim; and

b. a ferrite rod which is fixedly coupled to said bellows;

c. a passive circuit including a first coil which is mechanically coupled to said wheel rim and a second coil which is electromagnetically coupled to said ferrite rod, which is slidably coupled to said second coil, all of which are electrically coupled in series to form a tuned circuit which resonates at a particular frequency which is dependent on the position of said ferrite rod;

d. an oscillating circuit having a third coil of several turns on a rod of highly permeable material which is disposed adjacent to said first coil of said passive circuit on said wheel rim whereby said passive circuit receives energy from said oscillating circuit whereby the movement of said ferrite rod causes a change in the frequency at which said passive circuit resonates thereby producing a voltage across said third coil of said oscillating circuit which is proportional to the change of pressure in said pneumatic tire;

e. amplifying means for amplifying said voltage which is electrically coupled to said oscillating circuit; and

f. displaying means for displaying said amplified voltage in order to detect the change in frequency at which said passive circuit resonates thereby providing a measure of movement of said ferrite rod in response to the change in pressure of said pnuematic tire.

2. In a remote system for indicating tire pressure a mechanical electromagnetic pressure sensor according to claim 1 wherein said mechanical electromagnetic pressure sensor also comprises:

a. a pointer which is mechanically coupled to said bellows;

b. indexing means for providing a scale of the position of said pointer, said indexing means disposed adjacent, but not contiguous to said pointer so that said scale of said indexing means mechanically provides a direct and visual reading of the pressure in said pnuematic tire.