FR2733781A1 - Magnetic key for door lock - Google Patents

Abstract

The key is made from a ferromagnetic (AlNiCo) powder embedded in a hardening plastic material. The material is magnetised by using an electromagnet, to provide a uniform magnetisation. Spots within the magnetised material (13) have a stronger magnetic field applied locally, providing a secret magnetisation code.

Description

DESCRIPTION
The present invention relates to the field of locksmithing, and particularly to that of magnetic key locks.

 Generally, a lock is a closing device comprising a movable part, or bolt, which can penetrate into a fixed or keeper part, penetration being controlled by a removable or key element, introduced into a housing of the movable part. When it is desired to keep the possibility of opening secret, the key usually acts by the action of raised or hollow regions, cooperating with complementary regions integral with the bolt, these regions being ai-bitrarily designed to cooperate according to a determined mechanical coding, to authorize the opening or closing of the lock.

 In the field concerned, it is known to use, instead of mechanical coding implementing geometrically complementary regions, magnetic coding.

 For this, the key and the lock carry ferromagnetic elements, arranged in a mutual arrangement constituting a code, a provision authorizing movement of the bolt only when the fixed and mobile elements are opposite.

 Indeed, a magnetic key consists of a basic support, which must be magnetically neutral, in which a plurality of ferromagnetic elements have been included, magnetized according to a law of geometric distribution constituting the coding proper to each lock.

 The industrial production of such a key is expensive, because it involves, as regards the basic support, in the case of the choice of a metal such as duralumin or brass, operations of crimping individual magnets of a few cubic millimeters, and, in the case of the choice of a plastic material, the obligation to drown these elements by molding in the mass of the key.

 The key for magnetic lock of the present invention does not have any of these drawbacks.

 It is made of a homogeneous magnetizable material, and does not entail any obligation of crimping or inclusion of permanent magnets. Its realization leads to particularly advantageous costs, while allowing any distribution, in number and in layout, of the magnetized regions specific to each desired code.

 More specifically, the present invention relates to a key for magnetic lock, characterized in that it consists of a homogeneous magnetizable material, the magnetized regions proper to the secret code of the lock being produced by localized magnetization, with magnetic means applying a field. magnetic coercive higher than the residual magnetic field of said material.

 The invention will be better understood with the aid of the description below, based on the appended figures or: - Figure 1 shows, schematically, a magnetic key according to the known art.

- Figure 2 shows, schematically, a magnetic key according to the present invention.

- Figure 3 shows a magnetic clamp for magnetization
of a key according to the invention.

- Figure 4 shows a permanent neodymium magnet.

- Figure I shows, schematically, a magnetic key according to
known art
It consists of a main body (I), and a part
complementary (2)
The main body, made of an a-magnetic material supports a plurality of ferromagnetic elements such as (3), permanently magnetized with their magnetic axis perpendicular to the main body.

 The external faces of the key are covered with a layer (4) of an a-magnetic material, intended to ensure the protection and the maintenance of the magnetic elements as shown in partial cutaway.

The magnetization of some of these elements, according to a choice and a
distribution representing the secret coding of the lock, is carried out in the workshop, using electromagnets.

The cost of producing such a key is significant, both by that of
magnetic elements themselves, only by machining and crimping operations in the main body of the key.

Figure 2 shows, schematically, a magnetic key
according to the present invention.

It consists of a main body (ii) and a part
complementary (12).

Unlike the magnetic key of the known art, shown in Figure 1, the key of the invention is made of a homogeneous material in its
all, magnetizable at any desired point This material consists of a
powder of a ferromagnetic product, such as an alloy of the Ai Ni Co type, or
a ferrite-type ceramic, arranged in this homogeneous manner in a binder
curable such as rubber, or non-magnetizable plastic.

The coding specific to each lock can be carried out according to any
desired magnetic distribution, with magnetized regions, since the key is magnetically homogeneous in all its points.

 In FIG. 2, these regions are represented by hatched areas (13).

 FIG. 3 represents a magnetic clamp allowing the magnetization of a key according to the invention.

It consists of a pair of plates (30) and (31), which can be separated by two arms (32) and (33) joined by a hinge (34). These plates carry housings such as (35), to receive, in any desired distribution, the pole pieces of electromagnets. The magnetizing key is inserted between the plates, precisely guided in position by the guide pins (36), and the desired magnetization is thus carried out in the workshop
FIG. 4 represents a permanent magnet, made up of a magnetic alloy with neodymium, chemical body of the lanthanide family. This magnet (40) is fixed in an individual non-magnetic support (41), which carries a thread (42). This thread is designed to cooperate with the housings such as (35), also threaded, of the part of FIG. 3
Figure 4 shows a permanent magnet, made of an alloy
magnetic with neodymium, chemical body of the lanthanide family. This
magnet (40) is fixed in an individual non-magnetic support (41), which
carries a thread (42). This thread is designed to cooperate with
housings such as (35), also threaded, of the part of Figure 3
This type of magnetic alloy has a higher coercive field
in the remanent field of homogeneous magnetic material of which are
constitute the keys to the invention.

The magnetization of such keys according to any desired distribution is then carried out very simply, outside the workshop, by placing neodymium magnets in the housings of the two plates (30) and (31)
It should be noted that the permanent magnets described in the present application are indicated as being constituted by ferromagnetic alloys with neodymium, but it is understood in the field of the invention the use of any other alloy satisfying the characteristics (

Claims (1)

R.1. Key for magnetic lock, characterized in that it consists of a homogeneous magnetizable material, the magnetized regions specific to the secret code of the lock being produced by localized magnetization with magnetic means applying a coercive magnetic field greater than the remanent magnetic field Dudit material; R.2. Key for magnetic lock according to R.1., Characterized in that said homogeneous material is a ferromagnetic alloy. R.3. Key for magnetic lock according to R.1., Characterized in that said homogeneous material is a powder of a ferromagnetic product dispersed in a curable binder. R.4. Key for magnetic lock according to R.3., Characterized in that said ferromagnetic product is an alloy of the Ni Co type R.5. Key for magnetic lock according to R.3., Characterized in that said ferromagnetic product is of the ferrite type. R.6. Key for magnetic lock according to R.3, characterized in that said curable binder is a plastic material R.7. Key for magnetic lock according to any one of the preceding claims, characterized in that the said magnetization is carried out by the use of an electromagnet. R.9. Key for magnetic lock according to R.1, characterized in that said localized magnetization is carried out by the use of a permanent neodymium magnet.