FR2545137A1 - Safety lock - Google Patents

Abstract

This safety lock, of the cylinder type, comprises in a known way a tubular body 1 fixed to a fastening flange 2 and equipped at its outer end with a cap for protecting the cylinder. A sleeve made of hardened and tempered steel 4 surrounds this tubular body 1, relative to which it can rotate. According to the invention, a second outer sleeve 5, likewise made of hardened and tempered steel, surrounds the first sleeve 4 and can rotate relative to it. Thus, even if the outer sleeve is blocked, for example by means of pliers, a break-in by cutting through is prevented because the free rotation of the inner sleeve will oppose attack by the tool for the purposes of cutting it through.

Description

Safety lock.

 The present invention relates generally to locks and it relates more specifically to so-called safety locks, of the i cylinder type.

 Locks of this type are well known. They comprise a cylinder generally made of nickel silver, brass or a similar material containing the mechanism of the lock and housed in a tubular body usually made of steel, provided with a flange for fixing the lock on the palaster, the assembly being mounted. on the door.

 Since the material which constitutes the cylinder of the lock can be attacked in a relatively easy way by means of a tool such as a saw and that the tubular body usually made of steel which serves as housing for this cylinder does not represent -same, given its nature, that insufficient protection, it is known, in so-called safety installations, to fit around this tubular body a sheath generally made of treated steel, which turns freely around the tubular body and prevents burglary by access to the cylinder of the lock. This protection is then generally supplemented by a pellet itself, treated, for example case-hardened, which aims to avoid tearing and drilling.

 Mas practice has shown that even this treated steel sheath does not represent absolute protection, since it is still possible, for example by means of an appropriate pliers or a similar tool, to cause it to block in rotation and then to be able to saw or cut it, which makes it possible to access the tube forming the body of the lock and the cylinder thereof.

 The object of the invention is to remedy this drawback and to produce a lock for high-security installations opposing any break-in by sawing, cutting-off or in a similar manner.

 The invention is embodied in a cylinder type security lock housed in a tubular body itself surrounded by a protective sheath preferably made of treated material freely rotating around this tubular body, characterized in that it is provided around of this first sheath, a second outer sheath preferably also made of treated material, which can rotate freely relative to this first sheath.

 The combination of these two protective sleeves freely rotating with respect to each other and around the tubular body of the lock then opposes with certainty any break-in by cutting or sawing.

 Indeed, if one blocks the external sheath, for example by means of pliers or an equivalent tool, and if one tries to saw or to cut the sheath thus blocked, it will occur, at the moment where the cutting tool will have crossed the wall of said outer sheath and will come into contact with the inner sheath, a rotation of the latter inside the outer sheath, which will oppose any sawing or cutting of the two protective sleeves, allowing to reach the body or the cylinder of the lock. In addition, this second sheath in treated material increases the protection of the lock against shocks.

 The description which follows, made with reference to the appended drawing, given without limitation, will allow a better understanding of the invention.

 The single figure is a schematic representation with partial cutaway of a cylinder lock arranged according to the invention.

 In the drawing, there is shown at 1 the body of the lock, in which is housed the cylinder. This body has a tubular shape and it is integral with one end of a flange 2 which is generally fixed by screwing on the palaster of the lock.

 The cylinder lock body of this type is, as indicated above, generally made of steel, but it constitutes only insufficient protection against break-ins with intervention on the cylinder of the lock, which is itself made of a material relatively not very resistant to tools, like nickel silver or brass.

 It is known to improve protection by a treated or case-hardened steel pellet, which is indicated at 3 in the drawing and which is fitted in front of the body 1 of the lock to protect the cylinder against attempts at break-ins or drilling other.

 There is indicated in 4, in the drawing, a sheath of treated steel or similar material, which is adapted in a known manner around the tubular body-1 of the lock for protection purposes. This sheath rotates freely around the body of the lock, in order to normally oppose attempts to break in by cutting or drilling.

 However, as indicated above, an angular blocking of this protective sheath 4 is still possible, for example by means of pliers or the like, which then allows its cutting with a suitable tool.

 According to the invention, a second sheath 5 of steel or of treated material is fitted around the first sheath 4, with respect to which it can rotate freely.

 Like the inner sheath 4, the outer sheath 5 is provided at its end directed towards the flange 2 with a retaining flange 6, which opposes its release towards the front of the lock by tearing off once the lock is mounted in place.

 Since the inner sleeve 4 and outer sleeve 5 can rotate relative to each other, and furthermore since the inner sleeve 4 can itself rotate around the tubular crp s 1 of the lock, any attempt to sectioning exerted on the outer sheath 5 after angular blocking, for example by means of pliers, will be thwarted when the cutting tool reaches the inner sheath 4, since the latter will then rotate between the sheath exterior 5 kept stationary and the fixed tubular body 1 of the lock, which will oppose its attack by the tool.

 It is therefore understandable that the security of the protection which results therefrom is very greatly increased.

 As indicated above, the presence of this double sheath also increases the protection of the lock against shocks.

 Modifications can be made to the embodiment described, in the field of technical equivalences.

 Thus, according to a variant, the outer sheath could be angularly fixed, this in no way modifying in this case the possibility of free rotation between the outer and inner sheaths.

Claims (3)

 l.- Safety lock of the cylinder type housed in a tubular body itself surrounded by a protective sheath preferably made of treated material freely rotating around this tubular body, characterized in that it is provided around this first sheath (4), a second outer sheath (5) which can rotate freely relative to this first sheath.  2. A security lock according to claim 1, characterized in that the outer sheath (5) is made of treated material, in particular of treated steel.  3. A security lock according to claim 1 or 2, characterized in that the outer sheath (5) is provided at its end directed towards the inside with a flange (6) opposing its release by tearing.