GB2045328A - Key Operated Lock - Google Patents

Abstract

A key operated lock structure for, for example, a motor vehicle steering lock includes an inner member 10 which is rotatable and axially displaceable within an outer member 12, the inner member 10 having a key slot 11 into which a key sensor-element 16 projects such that, when a key is inserted into the slot 11, the sensor element 16 rotates and causes axial displacement of the inner member 10 relative to the outer member (Fig. 2) against a spring bias. Preferably the sensor is biased to close the key slot in the absence of the key. <IMAGE>

Description

SPECIFICATION Key-operated Lock Structures This invention relates to key-operated lock structures and is of particular application to steering wheel or steering column locks for motor vehicles.

An important safety feature for steering locks is that locking should not be effected until the key has been substantially completely withdrawn from the lock structure thereby avoiding inadvertent locking when the vehicle is travelling.

Mere turning of the key to the "LOCK" position thus does not effect locking.

One method of achieving this effect is described in British Patent Specification No 1,430,370 and includes the use of an actuating member or key sensor element which lies in the path of the key when inserted into the key slot, so that insertion of the key displaces the actuating member to move it radially outwards to effect longitudinal movement of an intermediate member slidably mounted at the side of the plug of the lock structure. The intermediate member co-operates with a detent which acts to retain the bolt in the unlocking position until the key is withdrawn.

Although the mechanism described in British Specification No. 1,430,370 operates reliabiy, it involves the use of a series of interacting components with consequent frictional losses and assembly and manufacturing costs. It is accordingly an object of the invention to obtain the above-described full-key-withdrawal facility in a simpler and more economical manner.

A more specific object of the invention is to provide a key-operated lock structure for incorporation in, for example, a steering wheel or steering column lock and which is simpler to manufacture and assemble than the structures at present employed for the same purpose.

According to the invention there is provided a key-operated lock structure which includes an outer member, an inner member having a key slot and arranged for rotation relative to the outer member upon insertion of the key, spring means acting between the inner and outer members in the direction of the axis of relative rotation between the members and a key sensor element carried by the inner member so that it tends to project into the key slot, characterised in that the key sensor element is arranged for rotation within a chamber formed in the inner member and is of such configuration that, when it is rotated upon insertion of the key, its effective dimension in the direction of the axis of relative rotation between the inner and outer members is increased, the sensor element acting between the inner member and a fixed stop to displace the inner member against the spring means.

As applied to a steering lock for a motor vehicle, the inner member preferably either includes or is attached to a retention element which acts to hold off the bolt for so long as the inner member is displaced, the arrangement being such that the sensor element cannot rotate back to its original position until the key is removed. In order to obtain a full-key-withdrawal facility, the chamber within which the key sensor element is disposed is located adjacent to the entry end of the key slot.

To simplify production of the lock structure, the key sensor element may be formed as an extrusion which, in cross-section, comprises a segment of a circle subtending an angle of the order of 1350 at the centre of the circle such that the sensor element has two abutment surfaces relatively inclined at said angle and interconnected by an acruate surface which functions as a re-action and bearing surface. The fixed stop is preferably provided by part of the outer member or by a part fixed to the outer member and has a stop surface extending at right angles to the direction of relative movement between the inner and outer members.

Thus, prior to key insertion, the key sensor element is urged by the spring means acting on the inner member into a position in which one abutment surface thereof is in face-to-face engagement with said stop surface and the other abutment surface of the key sensor element extends across the key slot at an inclination of 450 to the direction of key insertion, the sensor element preferably completely closing the key slot to prevent the entry of dust and dirt and thus serving the function of a shutter.

Although reference has been made above to one abutment surface on the key sensor element engaging one stop surface on the outer member, it will be appreciated that, as the key sensor element extends across the key slot, each end of the key sensor element is in engagement with the fixed stop surface so that the inclined face of the key sensor element extending across the key slot has a central portion intended to be engaged by the tip of the key and end portions which cooperate with the portions of the stop surface on either side of the key slot.

In the construction referred to above, the key sensor element is of constant cross-section throughout its length. However, in a modified form, the angular extent of the central portion is greater than that of the end portions such that it is of slightly greater than semi-cylidrical form, the axis of rotation of the sensor element being slightly offset from the key slot and the surface of the central portion of the sensor element then extending at right angles to the direction of key insertion.

Upon insertion of the key, the tip of the key engages the presented face of the key sensor element and causes rotation thereof within the chamber formed in the inner member. This rotational movement of the key sensor element results in linear movement of the inner member by interaction between the stop surface portions and the adjacent abutment faces of the key sensor element.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a diagrammatic sectional view of part of a steering column lock prior to key insertion, Figure 2 is a corresponding view after key insertion, and Figure 3 illustrates the key sensor element.

The construction includes an inner member 10 in the form of a lock plug having a key slot 11 and containing a tumbler assembly as described in British Patent Specification No.1,428,965 to which reference should be made, the plug 10 being arranged for rotation within an outer member consisting of a cylinder 12 and a housing 1 3 with a spring 14 acting on the inner end of the plug 10 to urge it outwardly relative to the cylinder 12. The plug 10 is formed with a transverse bore 1 5 which intersects the key slot 11 and a key sensor element 16 is contained within this bore with the ends of the element 1 6 projecting beyond the ends of the bore.

In cross-section, the key sensor element 1 6 has two flat abutment surfaces 1 7 and 1 8 which are inclined at an angle of 1350, the sensor element 1 6 being arranged to that it can turn through 450 between its limiting positions within the bore 15, the position shown in Figure 1 being one in which abutment surface 1 8 is vertical and the position shown in Figure 2 being one in which abutment surface 1 7 is horizontal.The mouth of the key slot 11 is defined by a surface 19, which is co-planar with the corresponding surface 20 located on the other side of the key sensor element 16, and by an inclined surface 21 which serves to guide the tip of an inserted key (not shown) into the required position for engagement with the sensor element 1 6.

The bore 1 5 is of segmental form in crosssection with the ends of the segment subtending an angle of 1350 at the axis of the bore, which axis is slightly offset from the key slot so that the sensor element 1 6 rotates about an axis at right angles to the axis of the key slot and offset from the position at which the key can contact surface 1 7 of the sensor element. In the condition shown in Figure 1, i.e. prior to key insertion, the surface 1 7 extends across the key slot at an inclination of 45" to the axis thereof so that the key sensor element 1 6 performs the function of a shutter and serves to prevent the entry of dust and dirt into the tumbler mechanism of the device.

As can be seen from the drawings, the housing 1 3 has an inturned flange 22 extending around a circular aperture within which the lock plug 10 is a close sliding fit, the ends of the sensor element 16 engaging the inner surface 23 of the flange 22 to retain and locate the plug 10 within the housing 1 3. Prior to key insertion, surface 1 8 of the sensor element 1 6 is disposed vertically in face-to-face engagement with the inner surface 23 of flange 22 and the plug 10 is urged by the spring 14 into its outer limiting position relative to the housing 13.

When the key is inserted, it is guided by the inclined surface 21 so as to engage surface 17 of the sensor element 1 6. Pressure applied by the key to the sensor element 1 6 results in rotation of the sensor element within the bore 1 5 and urges surface 1 8 of the element 1 6 against the inner surface 23 of the flange 22. As a result, the plug 10, which carries the sensor element 16, is displaced inwardly of the housing 13 into the position shown in Figure 2 in which the surface 17 of the sensor element 16 is disposed horizontally just clear of the key slot and the surface 1 8 of the sensor element 1 6 is disposed in abutting relationship with side wall 24 of the bore 1 5.When the key is fully inserted and the tumblers are retracted, the plug 10 can be rotated within the cylinder 12 to cause rotation of a cam (not shown) which co-operates with the locking bolt of the steering column lock to effect withdrawal thereof. The cam may be formed on or attached to the plug 10 and an interlock system is provided in per se known manner to ensure that, when the locking bolt has been withdrawn, it cannot return to its locking position until the plug 10 has moved from the position shown in Figure 2 into the position shown in Figure 1. Such movement is, of course, prevented for so long as the key is contained within the key slot 11 since the presence of the key means that reverse rotation of the key sensor element 1 6 is not permitted.Thus, regardless of the angular position of the plug 10, the locking bolt will be held off until the key is withdrawn. Furthermore, since the sensor element 1 6 is disposed adjacent the mouth of the key slot 11, the sensor element 1 6 will remain in the position shown in Figure 2 and the bolt will be held off until the key has been substantially completely removed. An impprtant safety feature is thus afforded.

In assembly of the device, the sensor element 16 is placed in the bore 1 5 and then the plug 10 is fed into the housing 13 from the inner end thereof to bring the ends of the sensor element 1 6 into engagement with the flange 22. The spring 14 and cylinder 12 are assembled with the plug 10 either before or after insertion of the plug 10 into the housing 13, the components of the device being fed into the housing 13, from the inner end thereof so that the use of accessible fixings or fastenings is avoided. This provides a further anti-theft feature in that it renders more difficult unauthorised disassembly of the components of the device.

The key sensor element 1 6 can be formed as an extrusion from either a metal or a synthetic plastics material of low-friction, high strength characteristics and may be of constant crosssection throughout its length.

As an alternative to the arrangement shown in the drawings, the central portion at least of the key sensor element 1 6 can be of semi-cyiindrical form with radiused edges. The key sensor element is then positioned so that the axis thereof is offset from the key slot whereby, upon insertion of the key, the sensor element is displaced from a position in which the flat diametral surface thereof is substantially at right angles to the axis of the key slot to a position in which the flat diametral surface is substantially parallel to the axis of the key slot.

Claims (5)

Claims

1. A key-operated lock structure which includes an outer member, an inner member having a key slot and arranged for rotation relative to the outer member upon insertion of the key, spring means acting between the inner and outer members in the direction of the axis of relative rotation between the members and a key sensor element carried by the inner member so that it tends to project into the key slot, characterised in that the key sensor element (16) is arranged for rotation within a chamber (15) formed in the inner member (10) and is of such configuration that, when it is rotated upon insertion of the key, its effective dimension in the direction of the axis of relative rotation between the inner and outer members (10 and 12) is increased, the sensor element (16) acting between the inner member (10) and a fixed stop (23) to dispose the inner member (10) against the spring means (14).

2. A key-operated lock structure according to claim 1, characterised in that, prior to key insertion, the key sensor element (16) completely closes the key slot (11).

3. A key-operated lock structure according to claim 1 or 2, characterised in that the outer member (12) is contained within a housing (13) having an inturned flange (22) at one end and that the fixed stop (23) is afforded by the inner surface of said flange (22).

4. A key-operated lock structure according to claim 1, 2 or 3, characterised in that the crosssectional configuration of the key sensor element (16) comprises a segment of a circle subtending an angle of the order of 135 at the centre of the circle.

5. A key-operated lock structure according to claim 1, 2 or 3, characterised in that the key sensor element (16) is of substantially semicylindrical form and that the edges thereof are radiused.