ANTI-THEFT STEERING LOCK DEVICE FOR MOTOR VEHICLES

Abstract: The device includes a stator (2, 3), a cylinder lock (4) oper­ able by means of a key(5), and a bolt (6,7). The bolt is kept in a retracted position by a cam (8) against the action of a spring (15) biasing it towards an extended position in which said bolt (6, 7) can lock the steering shaft. A security device (9 - 13) allows the movement of the bolt (6, 7) to the extended position only when the key (5) is removed from the lock (4). The sec­ urity device includes a latch member (11), slidable in the stator (3), and which is thrust outwardly as a result of the introduc­ tion of the key (5) into the lock (4), towards a working position in which it cooperates with a leaf stop spring (12) fixed to the bolt (6, 7). The leaf spring (12) has a free end which can inter­ fere with the latch (11) and pass over it when the bolt (6, 7) moves to the retracted position and can prevent the bolt (6, 7) from returning to the extended position as long as the latch remains in its working position.

Description: Anti-theft steering lock device for motor vehicles. The present invention relates to anti-theft steering lock devices for motor vehicles, particularly of the type associated with an ignition and starter switch. The invention relates particularly to an anti-theft steering lock device comprising a stator, a cylinder lock operable by means of a key, a bolt movable axially between a retracted position and an extended position in which it can lock the -steering; the bolt being kept in the retracted position by a cam fixed to the cylinder of the lock against the action of resilient means biasing it towards the extended position; and security means for allowing the movement of the bolt to the extended position only when the key is removed from the lock, the security means including a latch member slidable radially in a seat of the stator and adapted to be thrust radially outwardly, as a result of the introduction of the key into the lock, towards a working position in which it can cooperate with retaining means for retaining the bolt in the retracted position until the subsequent removal of the key. In devices of this type known at present, the latch member cooperates with a movable roller located in an aperture formed at one end of the shaft of the bolt and is biassed by a leaf spring, the roller locking the bolt in the retracted position when the latch member assumes its working position. This roller is a component of no small cost in that it must be made from expensive steel, worked with great precision by a machine tool and heat-treated by tempering and case-hardening operations. The object of the present invention is to provide a device of the type specified which can be made more simply and cheaply than known devices. In order to achieve this object, the present invention provides an anti-theft steering lock device of the type specified above, the main characteristic of which lies in the fact that the retaining means comprise a leaf stop spring fixed to the bolt; the leaf spring having a free end which can interfere resiliently with the latch and can pass over it when the bolt moves from its extended position to its retracted position, and can catch in the latch and prevent the bolt from returning to the extended position as long as the latch remains in its working position. According to a further characteristic, the stop leaf spring is associated with a further leaf spring also fixed to the bolt and having a free end which can interfere resiliently with the latch when the bolt is held in its extended position and thrusts the latch radially towards the cylinder lock when the key is withdrawn from the lock, to disengage the stop spring and allow the bolt to return to the extended position under the action of the said resilient biasing means. Both the stop leaf spring and the unlocking leaf spring may be made, conveniently, from blanked sheet metal. They are thus members which are simple and cheap to make. Further characteristics and advantages of the device according to the invention will become apparent from the detailed description which follows with reference to the appended drawings, provided purely by way of non-limiting example, in which: Figure 1 is a partially-sectioned, schematic, sideelevational view of an anti-theft steering lock device according to the invention, Figures 2 and 3 are schematic, partially-sectioned side views showing part of the device of Figure 1, on an enlarged scale, in two different operative conditions, and Figures 4 and 5 show leaf springs usable in the device according to the invention. With reference to the drawings, and particularly to Figure 1, an anti-theft steering lock device associated with an ignition and starter switch of a motor vehicle is generally indicated 1. The casing of the device is indicated 2 and by 3 is indicated a fixed body, or stator, housing a rotatable cylinder lock 4 operable by means of a key 5. In known manner, the key 5 enables the cylinder 4 to be turned to three different angular positions of which the first corresponds to the deactivated condition of the switch contained within the casing, the second corresponds to the condition in which the ignition and operating circuit is connected, while the third is the starting position. A bolt 6 is controlled by a shaped rod 7 movable axially within the casing 2. The translational movement of the rod 7 is driven in known manner via a cam 8 fixed to the cylinder 4 of the lock, as a result of the operation of the latter by the key 5. A radial seat 4a is formed in the cylinder 4 and a shaped member 9 movable therein serves to sense the presence of the key. A corresponding radial passage 10 is formed in the stator 3 and a shaped latch member 11 is movable therein. When the key 5 is in the position of insertion in or removal from the cylinder 4, the radial seats 4a and 10 are aligned with each other: when the key is fully inserted in the cylinder 4, the sensor 9 thrusts the latch 11 radially outwardly towards its working position (Figure 2) in which the latch remains when the key 5 is rotated (Figure 3). The end of the control rod 7 within the casing 2 has an inclined transverse appendage 7a to which are fixed the ends of two leaf springs 12 and 13, of which the first is shorter than the second. The assembly of the springs 12 and 13, viewed in plan in the direction of the arrow IV of Figure 2, is shown in Figure 4. When the bolt 6 is in its extended position, these springs extend undeformed in a plane at an angle to the general direction of movement of the rod 7, their free ends facing the lock. Moreover, these springs have respective lengths such that they both interfere resiliently with the radially-outermost end of the latch member 11 when the bolt 6 moves from its extended position to its retracted condition. When the bolt has reached this position, the leaf spring 12, which is shorter, is bent and passes over a radial protuberance lla of the latch member 11 (Figure 3) and jams, or catches against, a shoulder 77h of this protuberance. The bearing surface of this shoulder is inclined so as to be substantially perpend#cu#ar to the direction of the spring 12. When the bolt 6 is in the retracted position, the spring 13 interferes resiliently with an appropriately-rounded protuberance llc of the latch member 11 (Figure 3). The bolt 6 is thus retained in its retracted position due to both the retaining action of the cam 8 and the jamming of the leaf spring 12 against the latch member 11. The subsequent movement of the bolt 6 to the extended, locking position is possible only when the key 5 is withdrawn from the lock: in this condition, the radial seats 4a and 10 are aligned again and the spring 13 exerts a radial pressure on the latch member 11 to thrust the latch and the sensor 9 radially inwardly of the cylinder 4. Thus, the spring 12 can be freed and, under the action of a return spring 15 acting on the control rod 7, the bolt can move to the locked position. The springs 12 and 13 may be formed easily and cheaply from blanked sheet metal. With regard to these springs, it should be noted that the more common solution of the present invention lies in the use of two leaf spring elements for catching the stop latch member in the retracted position of the bolt and for facilitating and ensuring sufficient radial thrust on the latch member to unlock it, respectively. It is not necessary for the two leaf springs intended for these purl)oses to be separate: as shown in Figure 5, it is possil)le to blank an element from a single piece with two adjacent, parallel sprung appendages of different lengths, each fulfilling the function of one of the two springs described above. In the anti-theft steering lock device according to the invention, the security retaining device described above has a simple construction and is cheap because of both the limited number of components needed and the cheapness of the required workings and assembly, which may be easily automated.

Claims: CLAIMS 1. Anti-theft steering lock device for motor vehicles, particularly of the type associated with an ignition and starter switch, comprising a stator (2,3) a cylinder lock (4) operable by means of a key (5), a bolt (6,7) movable axially between a retracted position and an extended position in which it can lock the steering; the bolt (6,7) being kept in the retracted position by a cam (8) fixed to the cylinder of the lock (4) against the action of resilient means (15) biasing it towards the extended position; and security means (9 to 13) for allowing the movement of the bolt (6,7) to the extended position only when the key (5) is removed from the lock (4), the security means including a latch member (11) slidable radially in a seat (10) of the stator (3) and adapted to be thrust radially outwardly, as a result of the introduction of the key (5) into the lock, towards a working position in which it can cooperate with retaining means (12) for retaining the bolt (6) in the retracted position until the subsequent removal of the key (5), characterised in that the retaining means comprise a leaf stop spring (12) fixed to the bolt (6,7); the leaf spring (12) having a free end which can interfere with the latch (11) and pass over it when the bolt (6,7) moves from its extended position to its retracted position, and can catch in the latch (ill) and prevent the boit(6,7)from returning to the extended position as long as the latch remains in its working position. 2. Device according to Claim 1, characterised in that the stop spring (12) is associated with a further leaf spring (13) also fixed to the bolt (6,7) and having a free end which can interfere resiliently with the latch (11) when the bolt (6,7) is held in its extended position and thrusts the latch (11) radially towards the cylinder lock (4) when the key (5) is withdrawn from the lock, to disengage the stop spring (12) and allow the bolt (6,7) to return to the extended position under the action of the said resilient biasing means (15). 3. Device according to Claim 1 or Claim 2, characterised in that the stop spring (12), in its undeformed condition, lies in a plane inclined to the direction of movement of the bolt (6,7). 4. Device according to any one of the preceding claims, characterised in that the said further leaf spring, or unlocking spring (13), also lies in a plane inclined to the direction of movement of the bolt (6,7) in its undeformed condition. 5. Device according to Claim 3, characterised in that the latch (11) has a radial projection (lla) defining a stop shoulder (llb) which the stop spring (12) can engage; the surface of the shoulder (llb) being so inclined that the stop spring (12) bears thereon substantially orthogonally. 6. Device according to Claim 5, characterised in that the projection (lla) of the latch (11) is rounded to facilitate the passing of the stop spring (12) over it. 7. Device according to any one of Claims 4 to 6, characterised in that the latch (11) has a radial protuberance (llc) for interfering with the further leaf spring (13). 8. Device according to Claim 7, characterised in that the protuberance (ill) of the latch (11) is rounded. 9. Device according to any one of the preceding claims, characterised in that the springs (12,13) are of blanked sheet metal. 10. Device according to any one of Claims 2 to 9, characterised in that the springs (12, 13) are separate from each other. 11. Device according to Claim 10, characterised in that the springs (12,13) are fixed above each other to a control rod (7) fixed to the bolt (6), the stop spring (12) being shorter than the unlocking spring (13). 12. Device according to any one of Claims 2 to 9, characterised in that the springs are constituted by, two parallel spring tabs adjacent a single blanked sheet metal element, the spring tabs having different lengths.

Inventors: LATTANZI, GIUSEPPE, MAURI, CARLO
Applicants: MAGNETI MARELLI S.p.A.
Application year: 1986
Main classification: B60R25
IPC codes: B60R25