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Self latching magnetic latching device

  • US 5,362,116 A
  • Filed: 04/27/1993
  • Issued: 11/08/1994
  • Est. Priority Date: 08/13/1990
  • Status: Expired due to Term
First Claim
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1. A self latching device for latching, in a predetermined position, two members which are otherwise moveable relative to one another, the device comprising a latch arm and a retaining element which in use provides a latching shoulder for the latch arm to prevent relative movement of the members, at least one of the latch arm and the retaining element providing a strong magnetic field and the other having magnetic properties, the latch arm being arranged to be displaceably mounted on a first of said members and the retaining element being arranged to be associated with the second of said members, the latch arm being such that, only when the members are in the predetermined position and the latch arm and retaining element are axially aligned, under the influence of the magnetic field will the latch arm and retaining element undergo relative movement into a latching position wherein any substantial relative movement of the two members is prevented by the latch arm and latching shoulder interengaging, and the latch arm being displaceable under substantial manual force away from the retaining element to a retracted position so that the members may be moved apart, the device comprising a biasing means which biases the latch arm to the retracted position with a force less than an opposing force imparted on the latch arm by the magnetic field, the latch arm being moveable in a vertical direction between the latching position and the retracted position and including a first portion displaceably mounted within a through passage in a housing, a first end of the first portion extending from a first end of the through passage and engaging with the latching shoulder in the latching position, a sleeve connected to a second opposite end of the first portion which extends from a second end of the through passage and a second portion mounted substantially above and in line with the first portion and having a first end connected to the sleeve and a second, opposite end mounting a lift knob, the biasing means being disposed adjacent the through passage abutting against the housing and extending therebetween and a portion of the latch arm to bias the first portion into the retracted position, the second portion being moveable by way of the lift knob between a lower position and an upper position, one of either the first or second portions being rigidly connected to the sleeve, whereas the other is captured by the sleeve and is capable of limited movement with respect thereto, such that when the second portion is in the lower position the first portion can move independently of the second portion between the retracted position and the latching position, whereby the biasing means need not support the weight of the second portion when the latch arm is in the retracted position, but when the latch arm is in the latched position lifting of the lift knob to the upper position causes movement of the first portion to the retracted position.

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