| 摘要 |
<p>1,249,043. Track apparatus. GENERAL SIGNAL CORP. 17 Oct., 1969 [30 Oct., 1968], No. 51105/69. Heading B7N. [Also in Division H1] A magnetic proximity detector has a polarized reed relay arranged so that flux is diverted due to the approach of a magnetic mass to permit contact operation to effect energization of the relay coil to reset the contacts so that the coil is de-energized. So long as the magnetic mass is in the vicinity of the relay its contacts will continue to open and close. As shown the encapsulated relay 5, which may be mounted on an insulating support 22 on a rail for operation by a railway wheel flange, has a sealed reed contact unit 7 surrounded by the coil 6 and spaced a set distance from a permanent magnet PM. The flux from the permanent magnet is insufficient for contact closure but sufficient to hold the contacts closed and on approach of a magnetic mass such as a wheel flange the contacts open to de-energize a relay A which has contacts sets 10, 11. When relay A is deenergized its contacts 10 close to energize the coil 6 which recloses contacts 7 to de-energize relay A to open contacts 10 which disconnect the coil 6 so that contacts 7 reopen if the magnetic mass is still present and so the relay A is continuously opened and closed until the mass is moved away. The contacts 11 operate when relay A is de-energized and disconnect a relay B which will not reset whilst the relay A oscillates since a capacitor 17 does not recharge sufficiently during the intermittent reclosures of contacts 11. A set of contacts 14 of the relay B connect the supply to the coil 6 through a resistor 15 so that the distance from the switch 5 at which the magnetic mass effects initial operation thereof is reduced.</p> |
