ALARM FOR SIGNALLING TIRE MALFUNCTION

• US 3,638,180 A
• Filed: 07/23/1969
• Issued: 01/25/1972
• Est. Priority Date: 07/29/1968
• Status: Expired due to Term

• Current Assignee: Daniel Lejeune
• Original Assignee: Daniel Lejeune
• Inventors: Lejeune, Daniel
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): Cohen, Howard
• Application Number:
  US04/844,096
• Time in Patent Office: 916 Days
• Field of Search: 335/205 340/57,63,60,58
• US Class Current: 340/445
• CPC Class Codes: B60C 23/0425 Means comprising permanent magnets, e.g. Hall-effect or Reed-switches
• CPC Class Codes: G01L 17/00 Devices or apparatus for measuring tyre pressure or the pressure in other inflated bodies

Abstract

A permanent magnet is mounted on each wheel of an automotive vehicle. In case of low pressure in one of the vehicle tires, the external magnetic field of the magnet mounted on the wheel for that tire is modified by an automatic movement of either the magnet or a shunt associated therewith. A magnetic field responsive switch is mounted on the vehicle frame next to each wheel-tire assembly. The switch next to the malfunctioning tire responds to the change in the magnetic field to activate a signal alerting the driver of the vehicle.

Claims

1. An alarm for indicating to the operator of a machine such as an automotive vehicle, during operation of the machine, a malfunction associated with a rotating part thereof such as a wheel-tire assembly, comprising magnetic field responsive means mounted on the machine, the magnetic field responsive means being responsive to a static magnetic field, signal means mounted in a position such that, when activated, the operator is appraised of its activation, circuit means connecting said signal means to said magnetic field responsive means for response thereto, a permanent magnet mounted on said rotating part for movement along a path that is substantially stationary with respect to the machine and at a substantially constant distance from the magnetic field responsive means, and varying means operatively associated with said permanent magnet for maintaining the external magnetic field thereof at a low value when said rotating part is functioning properly and causing a sudden quantum increase in the external magnetic field thereof in response to a malfunction of said rotating part, whereby a malfunction of said rotating part increases said external magnetic field in such a manner as to cause said magnetic field responsive means to activate said signal means.

2. An alarm according to claim 1 wherein said varying means comprises a shunt.

3. An alarm according to claim 2 wherein said magnet is U-shaped and said shunt is a straight strip for selectively shielding and unshielding said magnet, said shunt when shielding said magnet covering the two poles thereof while being in spaced-apart relation thereto.

4. An alarm for indicating to the operator a machine such as an automotive vehicle, during operation of the machine, a malfunction associated with a rotating part thereof such as a wheel-tire assembly, comprising magnetic field responsive means mounted on the machine, the magnetic field responsive means being responsive to a static magnetic field, signal means mounted in a position such that, when activated, the operator is apprised of its activation, circuit means connecting said signal means to said magnetic field responsive means for response thereto, a permanent magnet mounted on said rotating part for movement along a path that is substantially stationary with respect to the machine and at a substantially constant distance from the magnetic field responsive means, and varying means comprising a shunt operatively associated with said permanent magnet for reducing the external magnetic field thereof when said rotating part is functioning properly and increasing the external magnetic field Thereof when said rotating part is functioning improperly, whereby a malfunction of said rotating part increases said external magnetic field in such a manner as to cause said magnetic field responsive means to activate said signal means, said magnet and shunt being displaceable relatively to each other and said varying means further comprising spring means mounted adjacent to said magnet and shunt and monitor means movable between a locking position in which it immobilizes said magnet and shunt with respect to each other and an unlocking position, said monitor means in response to a malfunction of said rotating part moving to said unlocking position, said spring means then effecting relative displacement of said magnet and shunt.