JPS58180348A - Steering gear lock - Google Patents

Abstract

PURPOSE:To make it impossible to give an external shock to the main part of a key cylinder, by providing a fragile part between the main part and head of the key cylinder. CONSTITUTION:A key cylinder 14 comprises a main part 15, in which a tumbler is housed, a head 16, into which a key is inserted, and a neck 17 which couples the main part and the head to each other. The neck 17 is provided with an annular groove 17a on the peripheral surface so that the neck is a fragile part. When the main part 15 remains locked by the tumbler, the neck 17 is broken at the annular groove 17a by excessive torque exerted due to the screwing of a drill or the like into the head 16 and the head disconnected from the neck is turned alone without dropping off a casing 11. For that reason, the drill or the like cannot be furthermore screwed in, so that the main part 15 cannot be removed. Theft is thus surely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steering lock for an automobile, and more particularly to a structure of a steering lock that takes into consideration safety against theft.

As is well known, a conventional steering lock generally has a structure as shown in the first diagram. That is, a locking bolt 2 for preventing the rotation of the steering column B is housed in a casing l attached to the steering column Alj, and in order to control the locking bolt 2,
A key cylinder housing 8 is built into the upper part of the casing l. A key cylinder 4, which is rotated by inserting a predetermined key into the key cylinder housing 8, is disposed inside the key cylinder housing 8, and a plurality of chains such as tumblers 5 are disposed between the key cylinder assembly and the key cylinder housing 8. A locking means is provided to lock the key cylinder 4 so that it cannot be rotated unless a predetermined key is inserted into the key cylinder number.

By the way, although a general steering lock is structured so that the key cylinder 4 cannot be removed from the key cylinder housing 8, sufficient protection is not provided against malicious acts such as using a tool such as a drill. It was difficult to imagine that. As a countermeasure to this problem, the head of the key cylinder 80 has been made of high-hardness steel, but this requires heat treatment to obtain high hardness, resulting in a very expensive device.

The present invention aims to prevent the key cylinder from being removed as described above, and includes a key cylinder main body on which a locking means such as a tumbler is applied, and a key cylinder head into which a key is inserted. The present invention proposes to provide a fragile portion between the key cylinder and the key cylinder that breaks when screwed-in torque from a drill or the like is applied, thereby making it impossible to apply an external impact to the key cylinder main body.

Embodiments of the present invention will now be described in detail with reference to FIGS. 2 to 4.

FIG. 2 shows a key cylinder 14 in the first embodiment of the present invention.
This key cylinder 14 is composed of a main body part 15 in which a tumbler is stored, a head part 16 into which a key is inserted, and a straight part 17 that connects these parts. A shaped groove 17a is formed as a weak part 7. Further, the head 16 has a stepped portion 16c formed by a small diameter portion 16a on the tip side and a large diameter portion 16b on the base side. A stepped portion 11c corresponding to the formed stepped portion 16c is formed to restrict movement of the head 16 in the axial direction. Therefore, when the main body part 15 is locked by the tumbler, if a drill or the like is screwed in from the head part 16, excessive torque acts on the neck part 17, so that the face part 17 breaks at the annular groove part and the broken head part 16 without falling off from the casing 11, it becomes impossible to screw in the drill any further, and the main body part 15 is not damaged until it is removed t.
Theft can be reliably prevented.

Figure 8 shows the present invention in which instead of cutting the neck Km-shaped groove, the outer peripheral surface of the cylindrical neck is removed from both opposing sides to form a substantially rectangular shape, and the neck z7 itself, which has a smaller cross-sectional area than the conventional one, is made a weak part. 2 shows a key cylinder 24 according to a second embodiment, in which movement of the key cylinder head 26 in the axial direction is prevented by engagement of stepped portions formed on the head and the casing, similarly to the embodiment in FIG.

Figure 4 shows the key cylinder main body 85 and the key cylinder head 8.
This is an eighth embodiment of the present invention in which the main body part 85 of the key cylinder 84 in this embodiment is made separately from the main body part 85 of the key cylinder 84. , these joint pins 87 are inserted into small holes 86a formed in the corresponding end faces of the head 86. An annular groove 86b is formed on the outer circumferential surface of the head 86, and an annular $Blb is formed on the head support cylindrical surface Bla of the casing 81 corresponding to the annular groove 86b. By fitting these, movement of the head 86 in the axial direction is restrained. Therefore, also in this example,
If excessive torque is applied to the head 86 while the main body 85 is locked by the tumbler, the joint pin 8? is broken, the head part 86 rotates freely, and it becomes impossible to screw a drill or the like into the main body part 85.

In addition, according to the research of the present inventor (c), the breaking torque of the fragile part is set to 80? It has been found that by setting the value within the range of cIn to 60 o'clock, it is possible to obtain a structure that is safe even with random key operations, and that prevents the locking part of a tumbler or the like from being destroyed.

After all, according to the present invention, a fragile part that breaks at a predetermined torque or more is formed between the key cylinder main body and the head, and the structure of the steering lock is such that the head does not fall off after being broken. It is possible to reliably prevent sudden mischief or theft caused by pulling out the key cylinder without using expensive cemented carbide alloy or the like.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional steering lock, FIG. 2 is a sectional view of a main part of a key cylinder in a first embodiment of the present invention, and FIG. 8 is a perspective view of a key cylinder in a second embodiment of the present invention. FIG. 4 is a partially cutaway sectional view of a key cylinder in an eighth embodiment of the present invention. l...Casing, 8...Key cylinder housing, 4, 14, 24, 84...Key cylinder, 5
...Tumbler, 11a, 16c, 26cm-
One step part (restraint means), 16, 25, 85... Key cylinder body part, 16, B6, 86... Key cylinder head, 17, 27... Neck part (weak M), 81... Joint bottle ( Weak part), 81b, 86b mountain annular groove (restraint means), 88...
Key (restraint means). Patent applicant Nissan Motor Co., Ltd. 7-

Claims (1)

[Claims] 1) In a steering lock in which a key cylinder is placed in a key cylinder housing fixed in a casing, and a tumbler provided between the key cylinder and the key cylinder housing prevents rotation of the key cylinder,
A fragile portion that is easily broken when excessive torque is applied to the key cylinder head is provided between the key cylinder body into which the tumbler is inserted and the key cylinder head into which the key is inserted. A steering lock characterized in that a restraint means is provided to prevent the head from moving in the axial direction.