Cylinder lock body

Abstract: A cylinder lock body comprises two cylindrical half-housings (2, 3) with two respective half-flanges (7, 8) connected by a bridge-like portion (9) in which a hole (10) is formed for a cylinder lock fixing screw. On one face of one of the two half-flanges (7, 8) and on the opposite face of the other half-flange there are secured two reinforcing elements (11, 12) which have a portion (11a, 12a) surrounding the hole (10) for the fixing screw. Each reinforcing element extends only on one of the two half-flanges, so that in case of flexural rupture of the lock body at the bridge-like portion (9), the two half-housings (2, 3) cannot be fully separated from each other, since the respective reinforcing elements (11, 12) freely rotatably engage the fixing screw with their highlet-shaped ends (11a, 12a) .

Description: The present invention relates to cylinder locks. In particular, the invention relates to a body of a cylinder lock, of the type comprising two opposite coaxial cylindrical half-housings, which are for receiving the cylindrical core of the lock, a flange extending on one side thereof, in which holes are formed for cylinder lock tumblers, said holes opening on an inner cavity of the cylindrical half-housings, said cylindrical half-housings being separated from each other by a notch which is to be occupied by a rotatable pawl of the lock, said notch extending into the flange so as to define two half-flanges adjacent to the two cylindrical half-housings and connected to each other by a bridge-like portion, in which a hole is formed for engagement of a lock fixing screw, said body further including two reinforcing elements fitted within two opposite faces of said flange respectively, and each having a portion surrounding said hole. A body of a cylinder lock having all the above indicated features is known from DE-U-29 619 634. This document shows a cylinder lock body of the above indicated type in which the reinforcing element provided at each face of the flange has a substantially spectacles-like shape, with a central portion surrounding the hole for the fixing screw and two ends extending in the two above mentioned half-flanges. The problem which the device according to the prior art intends to solve is that of increasing the strength of the body of the cylinder lock at said bridge-like portion. Typically, the body of the lock is made of brass and therefore tends to brake at said bridge-like portion if it is subject to a bending deformation caused for instance by a burglar which engages one of the two half-housings by a tool and causes it to swing alternatively upwardly and downwardly until a rupture takes place at the weakened portion represented by said bridge-like portion. The device according to the prior art intends to increase the flexural strength of the lock body at the bridge-like portion, by adding two reinforcing elements at the two flange faces which are made of a high strength material, such as steel. Obviously, in order to achieve this object, it is necessary that each of the two reinforcing elements on each of the two flange faces extends by a substantial part on both the half-flanges, so as to contribute efficiently to the increase of the flexural strength of the lock body. The object of the present invention is that of providing a lock body of the type indicated at the beginning which is able to efficiently hinder the work of a burglar in a much more simpler and efficient way with respect to the above described prior art. In view of achieving this object, the cylinder lock body according to the invention is characterized in that on one face of the flange the respective reinforcing elements extends only on one half-flange and the bridge-like portion, whereas on the other face of the flange, the respective reinforcing element extends only on the other half-flange and the bridge-like portion. Due to the above indicated feature, if the body of the lock undergoes a flexural rupture at the above mentioned bridge-like portion, it is not possible anyhow to separate the two half-housings from each other, since the portions of each reinforcing element surrounding the hole for the fixing screw become freely rotatable around this screw, so that they prevent a separation of the two half-housings by being both anchored around this screw. As clearly apparent, the principle from the which the device according to the invention starts is different from that on which the device according to the above described prior art is based. As discussed, in the device according to the prior art, the reinforcing elements have the object to prevent a flexural rupture of the lock body. Therefore, it is necessary that each reinforcing element extends on both the half-flanges. In the case of the present invention, the reinforcing elements are not for preventing a flexural rupture of the lock body at the bridge-like portion. Rather, this rupture is considered as inevitable and the device is arranged so that once the lock body has been broken at the bridge-like portion, the two half-housings in which it is divided cannot be separated from each other. As a matter of fact, in this condition; each reinforcing element is freely rotatable around the lock fixing screw, so that it enables a relative rotation of the two half-housings of the body around the screw axis, while preventing a full separation of these half portions, since the same screw is rotatably engaged through the both the reinforcing elements. Naturally, this effect cannot be obtained in the device according to the prior art, since in this case each reinforcing element extends on both the half-flanges of the lock body. Therefore, if the burglar exerts a force sufficient to brake also the two reinforcing elements, the two half-housings are immediately separable from each other. In the case of the invention, the rupture of the reinforcing elements cannot take place and therefore the reinforcing elements prevent the separation of the two half-housings in any case, even after that the brass part is broken. It is naturally essential, as discussed, in order to obtain this result, that on one face of the flange the respective reinforcing element extends only on one of the two half-flanges, and on the other face, the respective reinforcing element extends only on the other half-flange. Further features and advantages of the invention will become apparent from the description which follows with reference to the annexed drawings, given purely by way of non limiting example, in which: figure 1 a perspective exploded view of the cylinder lock body according to the invention, figures 2, 3 are two side views of the body of figure 1, and figures 4, 5 are cross-sectional views taken along lines IV-IV of figure 2. With reference to the drawings, numeral 1 generally designates a cylinder lock body, comprising two opposite coaxial cylindrical half-housings 2, 3 which are for receiving the cylindrical core of the lock (not shown). On one side of the cylindrical half-housings 2, 3 there extends a flange 4 in which holes 5 are formed, according to a technique known per se, which are for engagement of cylinder lock tumblers (also not shown), these holes opening on the inner cavity of the cylindrical half-housings 2, 3. The two half-housings 2, 3 are separated from each other by a notch 6 which is to be occupied by a rotatable pawl of the lock (not shown), the notch extending also through a portion of the flange 4, so as to define two half-flanges 7, 8 connected to each other by a bridge-like portion 9. The above described shape is known and conventional in this field. Also according to the prior art, the bridge-like portion 9 has a threaded through hole 10 for engagement of a screw (not shown) serving for fixing the lock body to a supporting frame secured for example to a door. On the two opposite faces of the flange 4 there are provided two reinforcing elements 11, 12 which are fitted within depressed seats of complementar shape 13 (only one of which is visible in figure 1) formed on the faces of flange 4. Both the reinforcing elements 11, 12 are made of steel, whereas the body 1 of the lock is typical made of brass. As clearly apparent from the drawings (particularly from figure 5) the two reinforcing elements 11, 12 each extend only on one of the two half-flanges 7, 8 and both have one end 11a, 12a extending on the bridge-like portion 9 and forming an highlet with a hole 11b, 12b surrounding the hole 10 for the fixing screw. As illustrated above, a burglar may try to cause a flexural rupture of the body 1 of the lock at the bridge-like portion 9, by engaging one of the two half-housings 2, 3 by a tool, and causing it to move alternatively upwardly and downwardly, until a complete flexural rupture of the body 1 at the portion 9 is obtained. According to the prior art, the reinforcing element provided on each of the two faces of flange 4 has a spectacles-like shape, with a central part surrounding the hole 10 and two end parts. As shown, in the case of the invention, each reinforcing element extends instead only on one respective half-flange, while having an end portion surrounding the hole 10. This simple difference of construction corresponds however to a relevant difference in operation. Instead, in the case of the known device, the two reinforcing elements are elements which tend to increase the flexural strength of the lock body. However, the burglar is able to exert a force sufficient to obtain the rupture also of the reinforcing elements, the two half-housings 2, 3 are immediately separable from each other and the burglar can then easily complete his work and remove the lock. In the case of the present invention, instead, the reinforcing elements 11, 12 do not give any contribution to the flexural strength at the bridge-like portion 9. However, if this rupture is caused, the full separation of the two cylindrical half-housings 2, 3 is not possible, since once the breakage has happened, the two half-housings 7, 8 are freely rotatable around the fixing screw which engaged the hole 10, since the end portions 11b and 12b of the reinforcing elements 11, 12 surround the screw. No matter how high is the force transmitted by the burglar, he will never be able to obtain the full separation of the two half-housings, even if the bridge-like portion 9 is broken. Therefore, as clearly apparent, the device according to the invention is able to provide a safety degree much higher against unauthorized brake, with much simpler and inexpensive means. Naturally, while the principle of the invention remains the same, the details of construction and the embodiments may widely vary with respect to what has been described and illustrated purely by way of example, without departing from the scope of the present invention.

Claims: Cylinder lock body, comprising two opposite coaxial cylindrical half-housings (2, 3), which are for receiving the cylindrical core of the lock, having one flange (4) extending on one side thereof in which holes (5) are formed for cylindrical lock tumblers, said holes opening on an inner cavity of the cylindrical half-housings, said cylindrical half-housings (2, 3) being separated from each by a notch (6) which is to be occupied by a rotatable pawl of the lock and extending in the flange (4) so as to define two half-flanges (7, 8) adjacent to the two cylindrical half-housings (2, 3) and connected to each other by a bridge-like portion (9), in which a hole (10) is formed for engagement of a lock fixing screw, said body (1) further including two reinforcing elements (11, 12) which are respectively secured to the two opposite faces of said flange (4) and each having a portion (11a, 12a) surrounding said hole (10), characterized in that on one face of the flange (4) the respective reinforcing element (11) extends only on one half-flange (7) and the bridge-like portion (9), whereas on the other face of the flange (4) the respective reinforcing element (12) extends only on the other half-flange (8) and the bridge-like portion (9). Cylinder lock body according to claim 1, characterized in that each reinforcing element (11, 12) has an highlet-shaped end (11a, 12a) surrounding said hole (10) for the fixing screw and an opposite end (11c, 12c) having a frame-like shape and secured to the respective half-flange (7, 8). Cylinder lock body according to claim 1 or 2, characterized in that each reinforcing element (11, 12) is constituted by a planar plate of steel fitted within a seat (13a) of complementar shape formed in the respective face of the flange (4). Cylinder lock, characterized in that it comprises a lock body according to any of the previous claims.

Inventors: MOTTURA SERGIO, MOTTURA, SERGIO
Applicants: MOTTURA SERRATURE DI SICUREZZA, MOTTURA SERRATURE DI SICUREZZA S.P.A.
Application year: 1999
Main classification: E05B9
IPC codes: E05B9