Device for the checking of the pressure of tires of a motor vehicle

• US 4,311,984 A
• Filed: 12/04/1979
• Issued: 01/19/1982
• Est. Priority Date: 12/04/1978
• Status: Expired due to Term

• Current Assignee: Elio Rigazio, Galileo Rossi, Piero Salussolia
• Original Assignee: Elio Rigazio, Galileo Rossi, Piero Salussolia
• Inventors: Salussolia, Piero, Rigazio, Elio, Rossi, Galileo
• Primary Examiner(s): Waring, Alvin H.
• Application Number:
  US06/100,250
• Time in Patent Office: 777 Days
• Field of Search: 340/58, 200/61.22, 200/61.25, 335/205, 335/206
• US Class Current: 340/445
• CPC Class Codes: B60C 23/0425 Means comprising permanent magnets, e.g. Hall-effect or Reed-switches

Abstract

A device for signalling the pressure in a tire fitted to a wheel of a vehicle, which device comprises a surveying member constituted by a cylinder in which there slides in sealing relationship a piston with a magnetic core in antagonism to a spring, to form a chamber in communication with the tire, the said surveying member being mounted axially on the rotating bearing of the wheel to find itself axially aligned with a sensor member fixed to a fixed part of the vehicle, the said sensor member comprising a couple of magnetic switches normally open and supported in mutual angular position and between which there is arranged a secondary magnet keeping the said switches closed, the magnetic core having a direction of magnetization opposed to the direction of magnetization of the secondary magnet, the proximity of these magnets causing the opening of the magnetic switches, an electric circuit being piloted by the opening of the switches to emit a signal.

Claims

1. A device for signalling the pressure in a tire fitted to a wheel of a vehicle, which device comprises a surveying member constituted by a cylinder in which there slides in sealing relationship a piston with a magnetic core in antagonism to a spring, to form a chamber in communication with the tire, the said surveying member being mounted axially on the rotating bearing of the wheel to find itself axially aligned with a sensor member fixed to a fixed part of the vehicle, the said sensor member comprising a couple of magnetic switches normally open and supported in mutual angular position and between which there is arranged a secondary magnet keeping the said switches closed, the magnetic core having a direction of magnetization opposed to the direction of magnetization of the secondary magnet, the proximity of these magnets causing the opening of the magnetic switches, an electric circuit being piloted by the opening of the switches to emit a signal.

2. A device according to claim 1, characterized in that the magnetic core mounted on the piston of the surveying member has a magnetic field intensity greater by many times than the intensity of the magnetic field of the secondary magnet that keeps the said switches closed.

3. A device according to claim 1, characterized in that the sensor member comprises an elongated hollow rod, in the interior of whose ends there are mounted the said switches and the said magnet, which are fastened by glueing, and the cables ending at the switch run along the rod.