TIRE PRESSURE INDICATION SYSTEM

• US 3,715,719 A
• Filed: 02/10/1971
• Issued: 02/06/1973
• Est. Priority Date: 03/03/1970
• Status: Expired due to Term

• Current Assignee: Uichiro Sugiyama
• Original Assignee: Uichiro Sugiyama
• Inventors: Sugiyama, Uichiro
• Primary Examiner(s): Waring, Alvin H.
• Application Number:
  US05/114,180
• Time in Patent Office: 727 Days
• Field of Search: 340/58 200/61.25,61.22 116/34
• US Class Current: 340/445
• CPC Class Codes: B60C 23/0425 Means comprising permanent magnets, e.g. Hall-effect or Reed-switches

Abstract

An air pressure responsive electric switch is mounted on a rotatable tire and wheel assembly of a vehicle and is subjected to the tire internal pressure. A magnetically actuated switch is mounted on a non-rotatable component of the vehicle, such as a brake mounting plate. A magnet is mounted on the tire and wheel assembly for rotation in a plane adjacent the magnetically actuated switch and is caused to operate the latter switch when the pressure responsive switch is operated responsive to a predetermined decrease in the tire pressure. The magnet may be an electromagnet whose energization is controlled by the pressure responsive switch, or it may be a permanent magnet normally retracted from operative relation with the magnetically actuated switch and moved to an operative position by the pressure responsive switch upon a predetermined decrease in the tire pressure. The magnetically actuated switch controls the activation of an indicating unit including an audible and visual alarm positioned in the driver'"'"''"'"'s compartment of the vehicle, and the control circuit for the indicating unit includes a thyristor, such as an SCR, whose gating is controlled by the magnetically actuated switch. The units mounted on the tire and wheel assembly and on the brake drum may be encased in an epoxy resin for protection against ambient conditions.

Claims

1. A system for detecting and indicating change of pressure in a pneumatic tire, forming part of a rotatable tire and wheel assembly mounted on a vehicle, comprising, in combination, an air pressure responsive switch device mounted on the rotatable tire and wheel assembly and subjected to the tire internal pressure;

a magnetically actuated switch mounted on a non-rotatable component of the vehicle;

magnet means mounted on the tire and wheel assembly for rotation in a plane of said assembly adjacent said magnetically actuated switch, and controlled, as to operative relation with said magnetically actuated switch, by said pressure responsive switch device;

said pressure responsive switch device, upon a predetermined change in the tire pressure, conditioning said magnet means to operate said magnetically actuated switch cyclically during rotation of said tire and wheel assembly;

a tire pressure change indicator unit observable by the vehicle operator;

circuit means connecting said indicator unit to said magnetically actuated switch for activation of said indicator unit responsive to operation of said magnetically actuated switch by said magnet means;

said pressure responsive switch device including a movable diaphragm subjected to the pressure in the tire;

a spring engaged with said diaphragm and resisting movement of said diaphragm responsive to the pressure in the tire;

a reset pin connected to said diaphragm for reciprocation responsive to movement of said diaphragm; and

operating shaft mounted to reciprocate perpendicularly to the direction of reciprocation of said reset pin;

said magnet means comprising a permanent magnet mounted on one end of said operating shaft;

said operating shaft being formed with a longitudinally extending groove having the outer end of said reset pin engaged therein;

spring means biasing said operating shaft to move in the direction of said permanent magnet to position said permanent magnet in operative relation with said magnetically actuated switch;

said magnetically actuated switch comprising a reed switch operable by said permanent magnet;

said reset pin being retracted from said groove, responsive to a change in the tire pressure, to provide for said spring means to move said operating shaft and said permanent magnet to a position in which said permanent magnet is in operative relation with said reed switch.