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

• Current Assignee: D&D Group Pty, Ltd.
• Original Assignee: David Doyle, Neil Dunne
• Inventors: Doyle, David, Dunne, Neil
• Primary Examiner(s): Lindsey, Rodney M.
• Application Number:
  US07/969,190
• Time in Patent Office: 560 Days
• Field of Search: 292/137, 292/144, 292/177, 292/251.5, 292/DIG. 62
• US Class Current: 292/144
• CPC Class Codes: E05B 65/0014 to prevent opening by children E05B13/00 takes precedence; child-proof container closures B65D50/00
• CPC Class Codes: E05C 19/163 a movable bolt being held in the striker by a permanent magnet
• CPC Class Codes: Y10S 292/62 Lost motion connections
• CPC Class Codes: Y10T 292/1021 Motor
• CPC Class Codes: Y10T 292/11 Magnetic

Abstract

A self latching device is disclosed which is arranged to latch in a predetermined position, two members which are otherwise movable relative to each other. The device comprises a latch arm arranged to be mounted to one of the members and which is movable between a latched and a retracted position , and a retaining element incorporating a permanent magnet arranged to be mounted to the other member. The latch arm is spring biased into the retracted position but, when in the predetermined position, is caused to move by the magnetic field generated by the magnet into the latched position wherein any substantial relative movement of the two members is prevented by the latch arm engaging the retaining element.

Claims

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.

2. A self latching device as claimed in claim 1, wherein the retaining element incorporates a recess having an internal wall surface which forms the latching shoulder for the self latching device.

3. A self latching device as claimed in claim 2 wherein the magnetic field is generated by permanent magnet located within the recess and the latch arm has magnetic properties.

4. A self latching device as claimed in claim 1 wherein the magnetic field is generated by a permanent magnet.

5. A self latching device as claimed in claim 4, wherein the magnet is a rare earth permanent magnet, formed from neodymium iron boron alloy.

6. A self latching device as claimed in claim 1 which further comprises a key operated locked mechanism which is operable to lock the latch arm in the latched position.

7. A self latching device as claimed in claim 1, the lift knob being located outside the housing and arranged to sit on a seat formed in the housing, the arrangement being such that when the lift knob is located on the seat, the first portion can move independently of the second portion between the latching and retracted positions, but when the latch arm is in the latching position, lifting of the lift knob causes an initial movement of the second portion relative to the first portion and thereafter causes a corresponding movement to be imparted to the first portion by virtue of the second portion captured in the sleeve engaging an edge surface of the sleeve, the corresponding movement causing the first portion to disengage the latching shoulder thus enabling the latch arm to move to the retracted position.

8. A self latching device as claimed in claim 1, the first portion and second portion comprising first and second elongate rods, respectively.