Apparatus for indicating pneumatic tire pressure

• US 3,930,223 A
• Filed: 09/14/1973
• Issued: 12/30/1975
• Est. Priority Date: 09/20/1972
• Status: Expired due to Term

• Current Assignee: Nicolas Fotios Tsagas
• Original Assignee: Nicolas Fotios Tsagas
• Inventors: Tsagas, Nicolas Fotios
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US05/397,427
• Time in Patent Office: 837 Days
• Field of Search: 340/58,52A 73/146.5 200/61.25
• US Class Current: 340/442
• CPC Class Codes: B60C 23/0422 characterised by the type of signal transmission means
• CPC Class Codes: B60C 23/0467 Electric contact means, e.g. slip-rings, rollers, brushes

Abstract

A transducer which communicates with the interior of the tire converts the pressure therein, when the pressure changes, into a corresponding motion which is picked up by a transmission and transmitted to a rolling electrical contact which rolls along a series of discrete electrically conductive members having resistances of different magnitudes associated therewith and corresponding to the tire pressure when a given electrically conductive member is engaged by the rolling contact member. Preferably the rolling contact member engages an electrically nonconductive insulating portion situated between the electrically conductive members in a region of normal tire pressure. The engagement of the rolling contact member with one of the electrically conductive members serves at least partly to complete a circuit which includes an indicator visible to the operator for indicating on a suitable scale the tire pressure.

Claims

1. In an apparatus for indicating pneumatic pressure of a tire carried by a vehicle wheel, converting means adapted to be placed in communication with the interior of the tire for converting variations in pneumtic pressure in the tire into mechanical displacements the magnitude and direction of which correspond to pressure changes, transmission means operatively connected to said converting means to be moved thereby and carrying first electrical contact means for moving the latter along a predetermined path in response to pressure changes, a plurality of discrete electrical contact means distributed along said path and each having a different resistance magnitude associated therewith and respectively corresponding to tire pressures when said first contact means engages the plurality of second contact means, an electric circuit connected to and formed in part by said first and second contact means to at least partly close said circuit when one of said second contact means is engaged by said first contact means, and an indicating device in the circuit and responsive to current flow, said indicating device being calibrated to indicate variations in tire pressure proportional to the magnitude of the current permitted to flow in the circuit by the relative positioning of said first and second contact means, said first contact means including at least one metal rolling means rotatably carried by the remainder of said first contact means and rollable along said path to have rolling contact with said plurality of said second contact means, so that friction between said first and second contact means during tire pressure changes when the vehicle travels is reduced to a minimum, said path forming part of a circle and said transMission means including a spring bias means having at least one pivotally mounted leaf spring connected through said transmission means to said converting means to be turned thereby and carrying said first electrical contact means for rolling the latter along said path and biasing said metal rolling means against said plurality of said second contact means, said rolling means being at least one wheel displaceable between a plurality of pairs of spaced apart metallic surfaces forming the second electrical contact means with the metallic surfaces of each pair being electrically interconnected and with the pairs of surfaces being electrically insulated from one another, whereby contact of said wheel with the second contact means is ensured for optimum periods despite vibrational influences.

2. Apparatus as claimed in claim 1, wherein the spring bias means is a leaf spring having two limbs with each limb carrying one wheel at its end and with at least one of said wheels being displaceable between said pairs of spaced apart electrically interconnected metallic surfaces;

said other wheel being displaceable in rolling contact over a plurality of further associated metallic surfaces with each of said further surfaces being electrically interconnected with one of said pairs of metallic surfaces.

3. Apparatus as claimed in claim 2, wherein the metallic surfaces of each said pairs of surfaces are offset relative to each other and to adjacent pairs to provide effective minimum spacing between different surfaces connected to different resistances to thereby ensure substantially continuous current flow in the circuit during displacement of said first contacts.

4. In an apparatus for indicating pneumatic pressure of a tire carried by a vehicle wheel, converting means adapted to be placed in communication with the interior of the tire for converting variations in pneumatic pressure in the tire into mechanical displacements the magnitude and direction of which correspond to pressure changes, transmission means operatively connected to said converting means to be moved thereby and carrying first electrical contact means for moving the latter along a predetermined path in response to pressure changes, a plurality of discrete, second electrical contact means distributed along said path to be engaged by said first electrical contact means during movement of the latter in response to pressure changes, said plurality of second contact means including a pair of intermediate substantially central second contact means spaced from each other by a distance substantially greater than the distance between any other pair of successive contact means, and the spaces between the plurality of second contact means being occupied by an electrically non-conductive insulating material in the same plane as said plurality of second contact means, so that between said pair of substantially central second contact means there is a relatively large non-conductive surface region, the latter being located in engagement with said first electrical contact means in the region of normal tire pressure so that said first electrical contact means remains out of engagement with any of said plurality of second contact means in the region of normal tire pressure, said plurality of said second electrical contact means respectively having different resistance magnitudes associated therewith and respectively corresponding to tire pressures, the vehicle wheel having a rotary part and the vehicle having a non-rotary part, said converting means, transmission means and said first and second electrical contact means being mounted on said rotary wheel;

part, an electric circuit connected to and formed in part by said first and second contact means to at least partly close said circuit when said first contact means enngages one of said second contact means, an indicating device in the circuit and responsive to current flow, said indicating device being calibrated to indicate variations in tire pressure proportiOnal to the magnitude of the current permitted to flow in the circuit by the relatively positioning of said first and second contact means, and an electric power source, said electric power source and said indicating device being mounted on said non-rotary part of the vehicle.

5. Apparatus as claimed in claim 4, wherein an electrical connection means comprises a continuous electrically conductive cylindrical surface mounted on an electrically insulating layer on said rotary wheel part, and rolling electrical contact means mounted on and insulated from the non-rotary part of the vehicle and spring biased into contact with said cylindrical surface and wherein said converting means, transmission means, and said first and second electrical contact means are mounted on a wheel hub;

wherein said electric power source and said indicating device are mounted on non-rotary parts of the vehicle, and one electric pole of the power source being connected to the rolling electrical contact means and the cylindrical surface being electrically connected to the second contact means and the other electric pole of said power source being connected to the body of the vehicle.

6. Apparatus as claimed in claim 4, wherein an alarm means and associated second electrical power source are incorporataed in a portion of said circuit in series with one of said contact means to be energised by displacement of said first contact means out of said insulating region provided between the intermediate pair of said contact means and indicative of a normal tire pressure, said first-mentioned power source and said indicating device being incorporated in a second portion of said circuit also in series with one of said contact means to be energised by engagement of said first contact means with one of said second contact means, and a switch means between said circuit portions for selectively connecting one or the other of said circuit portions into said circuit to de-energise said alarm means, after the latter has been energised, and then energise said circuit portion incorporating the indicating device to ascertain a tire pressure reading.

7. Apparatus as claimed in claim 6, wherein a plurality of gauge components each including said converting means, transmission means and a set of said first and second contacts are respectively mounted on the vehicle wheels and are incorporated in said circuit, the latter includng a single indicating device and said switch means for enabling each set of first and second contacts to separately complete the circuit with the indicating device.

8. Apparatus as claimed in claim 7, wherein said alarm means are electric lamps and are incorporated in said indicating device.

9. Apparatus as claimed in claim 6, in which said indicating device is a galvanometer.

10. Apparatus as claimed in claim 9, wherein a variable resistance and a fixed resistance are in series with said indicating device, said fixed resistance having a magnitude equal to the magnitude of the resistance associate with one of said pair of intermediate second contact means, so that said variable resistance can be manipulated to adjust said indicating device by comparison with said fixed resistance.