Devices for indicating pressure or temperature changes in pneumatic tires

• US 3,281,784 A
• Filed: 05/27/1963
• Issued: 10/25/1966
• Est. Priority Date: 05/27/1963
• Status: Expired due to Term

• Current Assignee: Edward Farthing Horace
• Original Assignee: Edward Farthing Horace
• Inventors: EDWARD FARTHING HORACE
• Application Number:
  US04/283,629
• Time in Patent Office: 1,247 Days
• US Class Current: 340/443
• CPC Class Codes: B60C 23/0425 Means comprising permanent magnets, e.g. Hall-effect or Reed-switches
• CPC Class Codes: B60C 23/20 Devices for measuring or signalling tyre temperature only

Claims

1. A DEVICE FOR INDICATING PRESSURE OR TEMPERATURE CHANGES IN PNEUMATIC TIRES ON VEHICLES INCLUDING A TRANSDUCER IN EACH OR A SELECTED TIRE OR TIRES OF THE VEHICLE, SAID TRANSDUCER BEING ADAPTED TO CHANGE ITS ELECTRICAL RESISTANCE PROPERTIES BY CHANGES OF AIR PRESSURE OF TEMPERATURE IN THE TIRE, A WHEATSTONE BRIDGE CIRCUIT IN WHICH THE TRANSDUCER IS CONNECTED AS THE FIRST ARM OF THE BRIDGE CIRCUIT, A VARIABLE RESISTOR FORMING THE SECOND ARM OF SAID CIRCUIT TO EFFECT BALANCE OF THE CIRCUIT UNDER NORMAL OR PREDETERMINED AIR PRESSURE OR TEMPERATURE CONDITIONS IN THE TIRE, A CENTRE TAP RESISTOR DIVIDING AN ENERGIZING CURRENT SOURCE INTO EQUAL HALVES TO CONSTITUTE THE THIRD AND FOURTH ARMS OF THE BRIDGE CIRCUIT AND A PAIR OF COMPLEMENTARY TRANSISTOR CONNECTED IN PARALLEL ACROSS THE BRIDGE CIRCUIT AND ARRANGED TO ENERGIZE SIGNAL MEANS IN THEIR RESPECTIVE COLLECTOR CIRCUITS ACCORDING TO THE DIRECTION OF FLOW OF CURRENT IN THE BRIDGE CIRCUIT WHEN THE LATTER CIRCUIT IS UNBALANCED BY AIR PRESSURE OR TEMPERATURE VARIATIONS IN THE TIRE.